| Title of Invention | "A FIBROUS COMPOSITION" |
|---|---|
| Abstract | Disclosed are modified ceilutosic fibers having a dry zero span tensile index that is substantially less than the dry zero span tensile index of the corresponding unmodified cellulosic fibers. Fibers having reduced dry zero span tensile may provide fibrous structures having improved hand feel compared with fibers prepared from unmodified fibers. In particular, such modified fibers provide fibrous structures with imroved flexibility, which is perceived as improved softness. The reduced dry zero span tensile is preferably achieved by reacting the fibers with one or more cellulase enzymes and one or more debondors. The invention also relates to a fibrous structure having a density of not more than about 0.4 g/cc, wherein the fibrous structure comprises modified cellulosic fibers having a dry zero span tensile index that is at least about 15% less than the dry zero span tensile index of the corresponding unmodified cellulosic fibers; and wherein the fibrous structure has a bending modulus per unit dry tensile that is at least about 30% less than the bending modulus per unit dry tensile of a fibrous structure prepared from corresponding unmodified fibers. |
| Full Text | FIELD OF THE INVENTION The present invention relates to a method for preparing modified cellulosic fibers useful in disposable products such as paper tpwels, facial tissue, toilet tissue, and the like. These fibrous structures provide improved hand feel/softness without sacrificing wet/dry tensile strength. BACKGROUND OF THE INVENTION Cellulosic fibrous structures, such as paper, are well known in the art. Such fibrous structures are in common use today for paper towels, toilet tissue, etc. To meet the needs of the consumer, these fibrous structures must balance several competing interests. For example, the fibrous structure must have sufficient tensile strength to prevent the fibrous structure from tearing or shredding during ordinary sue or when relatively small tensile forces are applied. The cellulosic fibrous structure must also be absorbent, so that liquids may be quickly absorbed and fully retained by the cellulosic fibrous structure. The cellulosic fibrous structure should also exhibit sufficient softness, so that it is tactilely pleasant and not harsh during use. Against this backdrop of competing interests, the fibrous structures must be economical, so that it can be manufactured and sold for a profit, and yet still be affordable to the consumer. Tensile strength, one of the aforementioned properties, is the ability of the fibrous structure to retain its physical integrity during use. As discussed by D. H. Page, "A Theory for the Tensile Strength of Paper", TAPPI. Vol 52(4), p. 674-82 (1969), tensile strength is controlled by two primary factors: fiber zero span tensile strength and fiber-fiber bonding (affected by, e.g. fiber sheer strength, relative bonded area, fiber length, fiber cross sectional area, and the average perimeter of the fiber oross section). With tissue and towel products and the like, the fiber zero span tensile strengths are generally on the order of at least 10 times greater than the overall tensile strength of the sheet- This in torn indicates that factors which influence fiber to fiber (i.e., interflber) bonding control the tensile strength of the web and that the zero span strength of the fiber (i.e., intraflber strength) can be reduced without adversely affecting overall product strength, Softness is the ability of a fibrous structure,to impart a particularly desirable tactile sensation to the user's skin. In general, softness is inversely proportional to the ability of the fibrous structure to resist deformation in a direction normal to the plane of the structure. Softness is influenced by bulk, surface texture (crepe frequency, size of various regions and smoothness), the stick-slip gurfnee coefficient of friction, and bending stiffhoss or drape (also referred as hand feel), One or more of these properties can be affected by fiber flexibility, fiber morphology, bond density, unsupported fiber length, and the like, Mot surprisingly, significant effort has been expended to enhance the tensile strength (wet and/or dry) of fibrous substrates; the patent literature is reflective of this effort, Examples of prior art means for increasing tensile strength are addition of chemical wet and dry strength agents, binder fibers such as bi-component fibers, latex binders, and the like. Similarly, significant effort has bean expended to provide -substrates having improved hand feel, or softness. Examples include addition of chemical softeners, surface modifying agent, clebonding agents, and the like. Other examples include mechanical treatment such as creping, Clupak®, Micrex®, 'wet miorocontraction, and the like. It is generally accepted that the strength of R fibrous substrate (typically measured in terms of wet and/or dry tensile strength) and that substrate's softness arc dependency related, at least to some degree. That is, effort? directed at enhancing substrate softness typically will result in a reduction in substrate strength, Indeed, many prior attempts to improve substrate softness have focused on,modifying (reducing) fiber-to-fibor bonds via chemical and/or mechanical treatments such as craping. While softness benefits ore achieved, a reduction in interfiber bonding gives rise to a reduction in substrate tensile strength and an increase in product lintiness. Thus,.there is a continuing need for a means to decouple the relationship between substrate softness and strength- In particular, there is a need for fibrous products having improved hand feel without sacrificing web strength. Accordingly, it is an object of.the present invention to provide a fibrous web, comprising cellulose-based fibers, which exhibits, improved softness without "negatively impacting strength to a significant deerae. This is achieved by preparing the webs using modified cellujosic fibers that have reduced a;ero span tensile strength (i.e., reduced intrafiber strength), as opposed to reducing the level of mterfjber bonding (i.e., mterftber strength) of the web, Mpre specifically, Applicants have discovered that a measurable reduction in the dry zero span tensile of fibers typjcally provides a fibrous structure that exhibits improved flexibility (as measured to terms of a, reduction in "bending modulus per unit dry tensile")' While a fftdwtipn In dry zero .span tensile strength does not always provide improvements in structure flexibility, such a reduction is , believed necessary to achieve more flexible structures in accordance with the present invention, It is a ftircher object pf the present invention to provide the above-described modified cetlulosic fibers as well an a provess for obtaining the modified cellulosio fibers. In one aspect, the present invention relates, to modified cellulose fibers having a dry zero span temjle index that is at least about 35% less than the dry zero span tensile (also referred to hereafter as "DZST") index, of the corresponding unmodified celluiosic fibers, ' In another aspect, the invention relates to a fibrous structure having a density of not more than about 0.4 g/cc, wherein the fibrous structure comprises modified eellulosic fibers having a dry zero span tensile Index that is at least about 15% loss than the dry zero span teixsilo index of the corresponding unmodified callulosto fibers; and wherein the fibrous structure has a bending modulus per wit dry tensile that is at least about 30% less than the betiding modulus per unit dry tensile of a fibrous structure prepared from corresporidmg unmodified fibers, Preferably, the rnodified fibers that form such a fibrous structurer when formed Into a haodsheet consisting only of those modified' fihera, will have a dry wnsile (also referred to hereafter as "DT") index that is at least as great as the dry tensile index of a hamjsheetraa.de from the corresponding unmodified fibers, The terms dry tensile index, dry zero span tensile index, and bending modulus per unit dry tensile, and methods for determining these parameters, are described in detail below, Briefly, the dry tensile index of a fibrous web corresponds to the strength pf the composite. In contrast, the dry zero span tensile index, though measured an a fibrous substrate, is a comparative measure of the intrinsic strength of individual fibers that make up that dry web, Although wet zero span tensile is generally recognized as a measure of intrinsic fiber strength Applicants believe the dry zero span tensile value is more predictive of the relative fiber and web flexibility, and therefor softness, of a substrate formed from modified cellulosic fibers that have reduced zero span tensile strength (i.e. reduced intrafiber strength), as opposed to reducing the level of interfiber bonding (i.e., interfiber strength) of the web. More specifically. Applicants have discovered that a measurable reduction in the dry zero span tensile of fibers typically provides a fibrous structure that exhibits improved flexibility (as measured in terms of a reduction in "binding modulus per unit dry tensile"). While a reduction in dry zero span tensile strength does not always provide improvements in structure flexibility, such a reduction is believed necessary to achieve more flexible structures in accordance with the present invention. It is a further object of the present invention to provide the above-described modified cellulosic fibers, as well as a process for obtaining a modified cellulosic fibers. Accordingly the present invention relates to a fibrous composition comprising ' modified cellulosic fibers and from 0.1 to 6% of a debonding agent such as hereinbefore described on a dry fiber basis wherein said fibers exhibit a dry zero span tensile index to wet span zero span textile index of from 1.5 to 3. According to the present invention there is provided a method for preparing modified cellulosic fibers, comprising combining one or more cellulase enzymes, cellulosic fibers, and one or more debonding agents, wherein the cellulosic fibers are allowed to react with the one or more cellulase enzymes and the one or more debonding agents for a period sufficient to reduce the dry zero span tensile index of the fibers by 35% to 65% compared with the dry zero span tensile index of the corresponding unmodified cellulosic fibers and to reduce the wet zero span tensile index by at least about 70% compared with the wet zero span tensile index of the corresponding unmodified cellulosic fibers, wherein the fibers are at least partially bleached. DETAILED DESCRIPTION OFTHE INVENTION I. Definitions As used herein, the term "dry tensile index-means the tensile strength of a fibrous structure, as measured in accordance with TAPPI standards T220 om-88 and T494 om-88 using an electronic tensile tester as described in the Test Methods, divided by the sample basis weight (sample weight per unit area). As used herein, the term "dry zero span tensile index" means the tensile strength of dry individual fibers that form a fibrous structure, as measured using a combination electronic/compressed air tester as described in the Test Methods section, divided by the sample basis weight (sample weight per unit area). While the measurement of zero span tensile index utilizes a fibrous substrate as the test sample, it is accepted that the resulting tensile index is a relative measure of fiber intrinsic strength. This is achieved by providing essentially zero gap between the jaws of the tester, as compared to a gap of 4 inches in the dry tensile strength test. As used herein, the term "wet zero span tensile index" means the intrinsic strength of wet fibers that form a fibrous structure, as measured using a combination electronic/compressed air tester as described in the Test Methods section. As used herein, the term "bending modulus -per unit dry tensile ratio" refers to the stiffness of a fibrous structure per unit tensile, as described in the Test Methods section. The dry and wet zero span tensile index measurements, as well as tending modulus per unit dry (ensile, are made on low density handuhoet structures produced in accorcteuca with the description set fort!) in the Test Method section. As used heroin, the term "modified fibers", means fibers that have been modified pvirsusmt to the present invention, aqch that the dry zero span tensile index is redact! by the indicated percentage (e.g,, at feast 15%, at least 3S%, etc.) native to the storting fibers, As uaed hereip, the term "unmodified fibers" refers to fibers that may have been processed via one or more operations commonly practiced in the industry, such as pulping, bleaching, refining, frotopulping, end the like, but have not ,'been modified in accordance with tlie teachings qf the present fipcclfkatipn, As used herein,'the term "softwood" means wood derived from coniferous trees. In one aspect, the present invention relates to modified cellulosic fibers having . dry zero span tensile Jndcs that is at least about 35% less than, preferably at least about 40% less than, still more preferably at least about "45% leas than, stilt more preferably at least about 50% leas than, still more preferably at least about 55% (ess than, the dry zero span tensile index of the corresponding unmodified'.cellulosic fibers. Typically, the DZST index of the modified fibers will be from about 35 to about 65% toss than the DZST of the corresponding unmodified fibers. In another aspect, the invention relates to modified cwellulosic fibers having a wet zero spsn tensile (alsolreferred to hereafter as "WZST") index that is at least about 10% Jess than, preferably at Jenst about 75% leas than, the wet sstiro span tensile index of the corresponding unmodified celluloeic fibers. In still another aspect, the invention relntes to modified cellulosic fibers that exhibit a ratio of dry zero span tensile index to wet zero span tensile index of from about 1.5 to about 3, typically from about 1.7 to about 3, more typically from about 2 to about ,3, In still another aspect, the invention relates tp a fibrous structure having a density of not more than about 0-4 preferably from about 0,04 g/cc to about 0-4 g/cc, more preferably from about 0,05 to about 0.3 g/cc, wherein the fibrous structure comprises modified cellulosic fibers having a dry zero span tensile Index that Is at,least about 15% less than the dry zero span tepaite index of the corresponding unmodified fibers; and wherein, the fibrous structure has a bending modulus per unit dry tensile that is at least about 30%, preferably at least about 33%, more preferably at least about 40%, less than the bending modulus per unit dry tensile of, a fibrous structure prepared from corresponding unmodified fibers, For purposes of the present invention, density is measured on a dry fibrous structure and is, calculated as the air dried basis weight of the structure divided by the thickness or caliper of the structure. Air dried basis weight and caliper are measured in a conditioned room where the temperature is 73oF ± 4oF (22.8oC ± 2.2oC) and the relative humidity is 50% ± 10%. The structure's caliper js measured according to TAPPI Test Meftpd'T 411 om89, with the modification that the test foot of the caliper tester exerts a pressure of 0.2 psi, Preferably, the fibrous structure comprises modified cellulosic fibers that have a dry zero span tensile index that is at least about 20% less than, more preferably at least about 25% less than, still more preferably at least about 30% less than, still more preferably at least about 35% lew than, the dry zero span tensile index of the corresponding unmodified collulosic fibers. It is understood that the density ranges described herein refer to the density of flic fibrous structure in its final form (i,e,, including any binders, strength agents, additives, softeners, surface modifying agent, debondipg agents, and the like, as well as mechanical treatments such as wet and dry crepingt wet and dry microcontraction, and the like), In contrast, die zero span tensile index, dry tensile index, and bending modulus per unit dry tensile measurements arc all made on low density handsheets comprising fibers (modified or unmodified) only, as described in the Test Method section below. With regard to fibrous structures, such structurw will preferably comprise modified fibers that, when those modified fibers are formed into a handsheet comprising only fibers (i.e., no additive, etc,), have a dry tensile (also referred to hereafter as "DT") index that is at least as great as the dry tensile index of a hwidshect made from the corresponding unmodified fibers, As used herein, the term 'at-least as great" means the handaheet comprising the modified fibers has a dry tensile index, that is at least about 90% of the dry (ensile index of a similar (in terms of density, basis weight, etc.) handsheet prepared from the unmodified fibers. Even more preferred is where the handsheet formed from, the modified fibers has a dry tensile index that is greater than a handsheet made from the corresponding unmodified fibers, for exarupla at least about 5%, more preferably at least about 15%, greater in terms of dry tensile index, Applicants have discovered that a measurable reduction in the dry zero span tensile of fibers typically provides a fibrous structure that exhibits improved flexibility (as measured in terms of a reduction in "bending modulus per unit dry tensile") and softness, While a reduction 'in dry zero span reduction does' not always provide improvements in structure flexibility, such a reduction .is believed, necessary to achieve more flexible structures in accordance with the present invention. In particular, Appoints have discovered that enzymatic treatment of fibers provides fiber morphologies that result in increased flexibility. While not wishing to bo bound by throry, it is believed that this increased fiber flexibility is related to the reduced dry zero span tensile values. Furthermore, became the ability of the modified fibers to bond, to one another has not been reduced significantly, the tensile strength of webs farmed from these fibers is not adversely impacted to the expected degree, indeed, Applicants have found that web tensile strength may actually increase relative to webs formed from corresponding untreated fibers. Thus, in a preferred embodiment of the present invention,' in addition to the dry zero span tensile and bending modulus properties discussed above fibrous substrates prepared from these modified1 fibers will have a dry tensile index of about the same or greater than the.dry tensile Index of a web made from corresponding untreated fibers. A. Fibers for Modification Fibers of diverse natural origin are applicable to the invention, so long as they arc susceptible to enzymatic activity. Digested, cdjuluse fibers from softwood (derived from coniferous trees), hardwood (derived from deciduous trees), cotton, or cotton (inters may be utilized. Fibers from Esparto prase, bagasse, hemp, flax, and other lignaceoys and cellulose fiber sources maym also be utilized as raw material in'.the invention. The optimum source of the starting fibers will depend upon the particular end use contemplated. Generally wood pulps will be utilized. Wood pulps useful herein include both sulfitc and sulfate pulps, ds well as mechanical, thormovmcchanical, and chcmi-thermo-mechanical pulps, derived from virgin or recycled fibrous sources, all of which are well known to those skilled in the paperrnaking art. Preferred wood pulps include chemical pulpd such as northern, southern and tropical softwood Krafts (i-e., sulfato); .northern, southern and tropical hardwood Krafts, including eucalyptus (such as Eucalyptus grandis, Eucalyptus saligna, Eucalyptus uropbilia,, Eucalyptus globulus); sulfite pulps (including northern, southern and tropical hardwoods and softwoods); and the like. Completely bleached, partially bleached and unbleached fibers are applicable, It may frequently be desired to utilize bleached pulp for its superior brightness and consumer appeal- Also useful in the present invention are fibers derived from recycled paper, which can contain any 'or all of the above categories as well as other non-fibrous materials such as fillers and adhesives used to facilitate the original paper making, The paper products formed from the modified fibers of the present invention may also contain non-cellulose fibrous material, for, example, glass fibers and synthetic polymeric fibers, Synthetic polymeric fibers useful herein include polyolefins, particularly polyethylenes, polypropylene and copolymers having at least one olefintc constituent,Other materinls such w polyesters, nylpns, copblymers thereof and combinations of any of tha foregoing may also bo suitable as the fibrous pplymeric material. Mixtures of any of the foregoing fibers may be used. B. pnzymeq it is recognized that upon reading Applicants' specification, any of the known cpllulase enzymes and/or cellwlase enzyme prepsratigns (which may include other enzymes,, such as hemicsjlulases, pectinases, smylascs, etc.) may be utilized to carry out the presept invention. Of the colluleses, several endoglucanases and exogiucanases are knovvn and twi be used, separately or in combinstjon, according to the present invention. The enzymes should be active and stable at the conditions, especially pH and temperature, that prevail during the pulp treatment processes. Representative examples of suitable enzymes are those derived from the microorganisms listed on Table A and Table B. Table .: Extunlcs. Agaricus bfsporus ASCoboulus fUrfiiraceus Ajpergillus aculeatus, A. fumigatus, A. niger, A. phoenicis, A, torreus &nd A, wentii Botryodiploida theobromae Chaetomium cellwlolytliciwn, C. gjobosum aad C, thermophilc Chrysosporium Hgnorum Cladosporiwm cladosporioidos Cqriolus versicoJor Pichomitussqualcns Bupeaicilliumjavanicum Fames famontarium Fusarium tnoniliforme, P aolwi and Pusarium spp. Hum icola grisea and H, insolons Hypocapre merdftria Irpex lactcus Lenzites trabw Mycellophtora thermophila Myriococcum ftlbomyccs Myrothecium verrucwla Paecilomycea fusisporus and P, voriotly Papulwpora thcrmophilja PellicuJaria fjlamentosa Fenicillium chrysogenum, P. citrioviridc, P. futilcolosum, P. notatum, P. pinophilium, P. vArmbilearid P. verruculoswm Pestalotiopsis versicolor Phajicrochacte chrysosporiutn PhiaJophora malorum Phoma hibertHca Phyearwm polycephalum , Pleurotua ostrca'tus and P. fiiy'caju Podospora decjplcns Polypous schweinitzil and P, varsicolor Poria placenta PoroniapunctatA PyricuUria orzyzae Saccobolus trunctarus SchizophyJIum commune Scleratinia llbertiana Sclerotiug} folfsii Scytalidium tignicola Sordaria firaicola Sporotrichum pulveruieptum and S. thermophile Stereum sanguinolentum Talaromyces cmersonii Thermoascus aursntlacus Thrausiothcca clavata Torula thermophile Trichoderma koningii, T. pstsudokoningii aad T, recsei Trichurus $piralis Vorticiiliupi albi>awum Volvariella voivacea Tftb^fl BL Examples of cellul^^-prodHcipf!! bacteria ' , Ccllulomonas flavigena, C. bia/otca, C. ctfllssea, C, flmi, C, gellda, C, cuitae, C, uda and C. turbato Bacillus brevis, B, firmya, B. tiohenformis, B. pumiltts, B. subtiiis, B. polymyxa And B, eereus S errata marccsccns 'Pswidomonas fluoresccns var, cpltHlosa' 'CeUvjbrio viridus, C, flavescens, C, ochrftccus, C, ftilvus. C. vulgaris and C. gilvus' Cytophaga butchinsonii, C. aurantiaca, C, rubra, C, tenulssima, C. winogradskli atd C, krzernienlewskw HprpoTosiphon geycericolus Sprorcytophaga myxococcoidcs Thermomonospora curvata The bacteria within prime sift^s arc npt v»lidly cjasslfjed, The fungi and bacteria listed above are. ;qnly given as examples. Presently wre strain pf Umajsala (o.g-,'Hi ressei) arc considered particularly suitable for the production pf the enzymes useful but the scope of the present invention is'not limited to the use of the .named microorganisms. It is very possible that other enzyme-producing microorganism? suitable for tho present invention already exist or will b* developed using mutation and selection or methods of genetic engineering. It is also likely, that the enzyme producing capabilities of an existing microorganism can be further enhanced through genetic engineering, A preferred cellulose enzyme userul herein ia Cclluclasr®, an enzyme sold by Enzyme' Process Division, Bioindijstrjal Group, N6vo Nprdisk A/S, Bagsvaerd, Denmark-Celluclast® is derived from the .fungus'Triohodermq tgesei. CeJIuclast® 1.5 L is a liquid cellulase preparation having an activity of ISOO'NCU/g, Activity is determined on the basis of Novo Cellulase Units (or "NCU&"), One NCU is the amount of enzyme which degrades carboxy methylcelluiose to reducing carbohydrates,with A reduction power corresponding to IxlQ* mol glucose per minute, at standard conditions of 40"C, pH 4,8, and a reaction time of 20 minutes, A more detailed description of the activity measurement is outlined in Novo Nordisk Analytical Method NO. AF 187,2 (available from NOVO Nordisk). Another preferred cellulase preparation useful herein is Celluzyme®, sold by Enzyme Process Division, Biokidustrjol Group, Novo Nordisk A/S, Bagsvaerd, Deiunvk. Celluzyme® 0.7T is a. grapulw callulase preparation that has an enzyme activity of approximately 700 CEVU/g and is derived from1 fifrmiicQl^ ujsolens. The activity is determined on the basis of Cellulase Viscosity Units (CEVU) under specified conditions outlined jn World Patent Publication No, WO 91/17243, published November 14, 1991 by fcasmussen et. al (the disclosure of which is incorporated herein by reference) and Novo Nordisk Analytical Method NO. AF 253 (available from NOVO Nordisk), Still another preferred cellulose preparation useful herein is Porgolase®, sold by Ciba, Qreensboro, NC. The Pergolase® A40 used is a liquid cellulase preparation that has at) active protein content of approximately 140 g/J., as measured by the Lowrey Method and is derived from Tricrtgderma reeic|. Pergolasa© A40 is * mixture of endo- and exacellu Uses, xylanases and mannftnasfifi. Still another preferred cellulose chosen for economic reasons is a product sold tinder the trademark Carczynw® by Novo Nordisk A/S, Cwezyme® 5.0 L is a liquid tellulase preparation that has an enzyme activity of approximately 5,000 CEVU/g. The activity is determined o» the basis of Cellulase Viscosity Units (CEVU) under specified conditions outlined In World Patent Publication No. WO 91/17243, published November 14, 1991 by RasmusBen et, al 'and NOVO Nordisk Analytical Method No. AF 253. Carczyme® is composed primarily of the family 45 endoglwcfcnase) EG V 0*43,000 kD molecular weight) ar homologues thereof, .derived from .HumicaJa in solar) a as described in WO 9 I/I 7243, Variants of the family 45 endoglueanMU found in Carezyme Patent: publication No^JVQjW April 14, 1994 by M. Schulein, et a|. (Ilia disclosure of which is incorporated herein by reference) and are believed to b« useful in modifying fibers in accordance with the present invention, As used herein, a "family 45" enzyme is an enzyme as described in Henrissat, B,;;e|:, a), fiionhem. J.. Vol, 293, p. 781-788 (1993), the disclosure of which is incorporated herein by reference, It is generally accepted that the endpglucaiwfic found in Carezyme® does not degrade highly crystalline cellulose, but degrades amorphous cellulose mainly to callobiasc, ccllotriose and celloteVraqse. Cc|lulclast®, Colluzym*®, and Pergalase© on the other hapd are combinations of endo wid exogluctwases and/or hetmcellnlases, As shown in the examples below, acceptable reductions in dry zero spun tensile are found with .nil enzyme preparations, which suggests that wide ranges of exo/endo ccllulytfp activity may be used » reduce dry zero cpftn tensile according to the present invention, It will bo recognized that etizymc addition to fibers may occur via an isolated enzyme preparation- Alternatively, microorganisms which contain or produce teJtulssc or cellulose-degrading enzymes may be combined directly with the fibers for modification- d Preari Mdiled Fibrs and Correspn'n-brous Structures In geneml, enzyme treatment of fibers to obtain the modified fibers of the present invention is accomplished by adding A cellulase'CQntainins enzymatic preparation to hn aqueous sjutry of fibers, and stirring the mixture for a period sufficient to allow action by the enzyme to modify the morphology of the fibers, After mining of the fibers and enzyme preparation, the mixture is preferably, though not necessarily, combined with a dcbonder or chemical softener (referred to herein collectively jus a "debondinjj agent") which Is believed to preserve the fiber morphology modificationa that result from enzymatic action. To obtain fibrous structures haying the appropriate properties for desired end-uses such ps paper towels, facial and'toilet tissues, and the like,,' it is preferred that fiber length not be reduced to a significant! degree during the modification process, The skilled artisan will recognize that fiber treatment conditions may vary depending on, for example, the nature of the fiber bplnfi treated, the en2yrne In genera), disintegrated pulp of the desired fibers is diluted with water Jp^make a fibrous slurry prior to combining with the enzyme, The slurry preferably has a pulp sonststency of at least about 0,5%, more preferably at least about 1%, still more preferably at least ajxiut 2%, As used herein, "pulp consistency" is the mass of the dry fibers divided by the total mass of the slurry. Preferably, the pulp consistency of the slurry will be not more than about 40%, to facilitate mixing of the enzyme and the slurry. Of course, higher consistency pulps may be utilized in practicing the present invention. In general, a separate enzyme solution is also prepared prior to combination with the fibers, The concentration of the enzyme solution may vary widely and will be determined by the relative activity of the , enzymes utilized, the fibers being treated, the degree of dry zero span tensile reduction desired,, the time and temperature of the reaction, And other related conditions. The pH of the fibrous slurry/enzyme mi?rture is adjusted, if necessary, to the appropriate fevel for the enzyme employed. The pH adjustment, if necessary, can occur prior to, during, or after combining of the enzyme and the fibrous slurry. The pH of the resulting mixture may be controlled using various ;buffcrs qr various acids or bases. In a particularly preferred embodiment using Carezytrie® and/or Celluzyme®, a pH of from about 5 to about $ is preferred. For other enzymes, .such as CelludasttSi and Pergojase®, a pH of about 4 to about 6 has been, found to be more preferred, After combining the fibrous slurry, enzyme, and any optional ptt adjustment, the mixture is reacted, preferably with agitation, for a period sufficient to reduce the fiber intrinsic strength in accordance with The present invention. The temperature of the mixture js preferably controlled between about SO and 160°F, more preferably 100 and 140"F, still more preferably between about 120 and 140°F. Typically, the mixture will be. reacted for a period of at least about 0-25 hours, more • typically for at least about 0.5 hours, even more typically for at least about J hour. Typically the mixture will be reacted for a period pf not more than about 4 hours,- more typically riot more than about 3 hours. Again, the skilled artisan will recognize that different reaction conditions, concentrations, etc, may be required to achieve the desired fiber modification, depending on the fibers being treated, the enzyme(e) used, the reaction temperature, the reaction time, the degree of dry zero span tensije reduction desired, the type of agitation employed, and the iike. The determination of how these variables may be adjusted is well within the level'of the skilled artisan, Applicants have found that while beneficial' intmfibcr weakening can be measured on the-wet fibers after enzymatic reaction (i.e., reduced wet zero span tensile strength), a certain amount of the reduced fiber strength is lost on drying of the fibers (i.e., dry zero span tensile strength). (See Tables 1 through 9 below.) However, by adding a dcbondinc agent to the wet enzyTOc-modified fibers, n farther reduction in dry zero apao tensile may be accomplished relative'to fibers treated with enzyme alone, Appllpants have also found that While certain debonding agents do not provide a significant reduction In DZST of the fibers, they do provide fibrous structures of improved flexibility without adversely IrnjuicTtng the Structures' dry tensile strength. A? such, in a particularly preferred embodiment, after the requisite reaction of the pulp islurry and the enzyme solution, a debonding agent is added to the mixture and is allowed to rewt, typically for at least about 3Q seconds and preferably at least about 5 minutes and more preferably for at least about 30 minutes to about 60 minutes, with constant racing. It will be recognized that the debonding agent may b» added to the fibers before or during combination with the enzyme, so Ions as the disbanding agent does not interfere with the activity of the enzyme utilized. Any debonding agent (or softener) known in the art may be utilized in this preferred embodiment, Examples of useful agents are tertiary amines and derivatives thereof;, ^mine oxides; quaternary amin«} silicorte-based compounds; saturated and unsaturated fatty acids and fatty ». „.—•——*- n .--- 1973 to Freimark ei alU.S. Pat. NO, 3,844,880 fa*w^~29~ \97Q Meisel et nl.). U.S. Pat. Ho. 3,916,058 (Issued "Qpj' 1975 to Vossos et al.),^U.S^PatjNo_. 4^028, 1 72 (issued Jun. 7, 197? to Mazzarclla ct alOU-SJwnNa. ,069.159 (issued Jan. 17, 1978 to HayeKJj U.S. Pat, No. 4,144,122 (issued M«- 33, 1979 to Emanuelsson ot a],), U.S. Patent No. 4j5i,594)S8uedlunri?r WP to Becker ef al), U.SPa;. No. r. 10, 1981 to Rudy et al.), U.S. Patent No> 4,3 H.QQjJissj&dFpb. 2, l982).y.S, Pat. No, 4.377,543 (issued Mar. 22, J983 to Strohbeeji et ^-) (issued Feb, 21, 1944 toreese et aj.), JJ^Pat. NO, 4,77^5 Jssued Oct. II, 1988 to Nueaslein et jtlQ^Uj. Pat.. No. 4^^531 PJisauod Jen, 3, 1989 to Soereas et al,), U.S. Pat, No. 4,937,Qp8Jissued JurT. 26, 1990 to Yamamura et aI.)..UtS, fat. Huv4,9gQ^41 (issued Xug, 21, 1990 to Walter et al^.SJto, .No, SjOZ^^^CiMued Jun, 25, 199 Ho Snow et al,), U.S, Pat. No, '5,0$ 1,196 (issued Sep, 24, 1991 to Plumenkopf « al,), y.Sr'Pat. Nn. Jur», 25, 1996lo Kaun Ct »!.), VJ/S. Pai No. 5P552,02Q (issued Sep. 3, 1996 to Smith et al.}, U.S, Pet, No, 5,555,873,(issued Sep. 24, 1996 to Funk et at-), US, Pat, No, 5,580,566 (i$sue Applicants have found that the degree of agitation during treatment of the fibers according to the present invention is also, an important variable affecting the degree of dry ¥>• •- ' -.. i zero span tensile reduction. While agitation is not necessarily required according to the present invention, ?n general, agitation increases tfie reduction in dry zero span tensile, other conditions being the same, Indeed, as shown in Example 1, and in particular Samples 1O and IP, where treatment of » 10 to 13,3 % consistency slurry cairwd out using a high intensity laboratory mixer provides fibers of lower dry zero span tensile than those obtained using low intensity shaft mixing (Sample IE) of a lower consistency slurry, all other variables being (he same, The high,intensity laboratory mixer used in Example 1. is generally recognized to represent the mixing intensity found in mediqm consistency pumps and high shear miners'used In industrial practice, .The skilled artisan will recognize that parameters affecting this degree of agitation include', but iw« not limited to, consistency of the mixture, mixing rate, and size and geometry of the reaction vessel and the mixing device. . After enzyme and preferred debonder treatment:, the modified fibers are formed into a fibrous structure using any of the known methods for \veb manufacture. These fibrous structures can comprise any conventionally -fashioned sheet or web having suitable basis weight, caliper (thicjcneja), absorbency and strength characteristics suitable for the intended end use. A fibrous structure of the preientinvention can be generally defined as a bonded fibrous product in which the enzyme modified fibers are distributed randomly as in "air-laying" or certain "wet-laying" processes, or with a degree of orientation* as in certain "wet-laying" or "carding" processes, The fibers can optionally be bonded together with a polymetfic binder resin, Conventionally, fibrous structures of the present invention arc made by wet-Jayins procedures* in such procedures, a web is' made'., by forming an aqueous papcrmaking ** • furnish comprising partially or all enzymepiriodifiRd fibers of the present invention, depositing this furnish onto a for»minous surface, such as s Fourdrinier wire, and by than removing water from the furnish, for example by gravity, by vacuum assisted drying andv'or by evaporation, with or without pressing, to thereby form a fibrous structure of desired fiber consistency. In many cases, the papcrrjmkmg apparatus is set up to rearrange the fibers in the slurry of the papermaking furnish as dewaterlng proceeds in order to form webs of especially desirable strcugth, hand, hulk, appearance, nbsorbency, etc, The papcrmaking furnish utilized to .form preferred fibrous structures essentially comprises an aqueous slurry of thp modified fibers qf the present invention and c&i optjgnaUy contain » wide variety of chemicals such as wet strength resins, surfactants, pH control agents, softness addjtivea, dcbonding agents and the like, A number of paperroaking processes have been devejopsd which utilize a apparatus that forms webs having particularly useful or desirable fiber Such configurations can serve,to impart such characteristics pf the paper web as enhanced bulk, absorbeney and strength, One such proces? employs an imprinting fabric in the papcrmaWng process that serves to impart ft knuckle pattern of high density and low density zones into the resulting paper Web. A process of this type, and the ' i paperroakmg apparatus for carrying out this process, is described in greater detail in U.S. Patent 3401,746 (Sanford fit al), issued January 31, 3967, which ii incorporated by rdferense. Another pnpennaking process carried out with a special paper-making apparatus Is one that provides a paper web having a distinct, continuous network region formed by a plurality of "domes" dispersed throughout the network region on the substrate. Such domes are formed by compressing an embryonic web as forced during the pftpermakinij process into a foraroinoiis deflection member having ft patterned network surface formed by a plurality of discrete isolated deflection conduits in the deflection member surface. A. process of tins type, and apparatus for carrying out such a process, is described in greater detail in U.S. Patent 4,529,480 (Trokhan), Issued .July 16, 1985; U.S. Patent 4,637,859 (Trokhan), issued January 20; 1987; and; tXS, Patent 3,073,235 (Trokhan), issued Depember 17, 1991j all of which are incorporated by reference, Another type of papermaking proc«ss> and apparatus to carry it o'Ut that is suitable for making layered composite paper substrates is described in U,S. Paten? 3,994,771 (Morgan et alO, issued November 30,1976, which is ineprpormed by reference. Still another papermaking process that can utilUe the fibers of the present invention is one that provides a paper w»b having a continuous high basis weight network region surrounding discrete lp>v basis weight regions. The,, webs are formed using a forming belt having zones of differing flow resistances arranged |n a particular ratio of flow resistances. In general, the basis weight of a given region is inversely proportional to the flow resistance of the corresponding zone of the forming belt A process of this type, and apparatus for carrying out such a process, is described in greater detail in U*S, Patent 5,245,025 (Trokhan etal), issued September 14, 1993; U.S. Patent No, 5,503,715 (Trokhan et»!.), issued April 2, 1996; afld U.S, Patent No, 5,534,326 (Trokhan et A!.), issued July 9> 1996; the disclosure of each of which is incorporated herein by reference. Yet another papermaking process that can utilize the fibers of the present, indent! on 3s one that provides a layered paper web having a smooth, vetutinous surface, Tha web is . formed using relatively short fibers, where the top surface of the web is processed snuji that Wterfibcr bonds are broken to provide free fiber encjs thqt improve tootility. A process of This type is described in detail in U.S. Patent No, 4,300,981 (Carstens). issued November 17,1981, the disclosure of which is incorporated by reference herein, Another papermakmg process cmplpys a tbroughdryirts fabric having impression knuckles raised above the plane of the fabric. These impressions create protrusions in the througbdried sheet, and. provide the sheet with stretch in the crosa^aphine direction. A process of this type is described in European Patent Plication No. 677,6"12,A2; published October 18, 1995 by O, Wendt et a).» the disclosure of which is incorporated herein by reference. The preferred fibrous 'structures can form on« of two or more plies that can 'bp laminated together; Lamination, and lamination- carried out in combination with n*i embossing procedure to form « plurality of protuberances in the laminated product is described in greater det*.il in U-S, Patent 3,414,459 (Walls), issued December 3, l£>6&, which ia incorporated by reference. These paper $u,bifr»tes preferably have a basis weight of between about 10 g/m2 and about §5 g/m^, and density of about 0,6 g/cc or less, More preferably, the basis weight Will be about 40 g/rn^ dr less and the density Will be about 0.3 g/cc or less. Most preferably, the density will be between about 0,04 S/cc wd about 0,2 g/cc, Unless oiherwiw ppecifiedi all amounts and weights relative to. the paper web substrates are on a dry basis,) In additioii to the rnodified fibers of the present inversion, the pspcrrn&king furnish used to make the fibrous structures con have other components or maierials added thereto as can be or later become'kjjpwn in the an, Th« types of additives desirable will ha dependent upon the particular end-lisa of the tissue' sheet contemplated- for example, in products such as toilet paper, paper towels, facial:tissue*, baby wipes and other similar products,, high wet strength is t desirable attribute, Thus,, it is often desirable to add to the papermaking ftirnish chemical substances known in the art as "wet strength* resjns. A general dissertation on the types of wet strength resins utilised in the pnper on can be found in TAPPI monograph series MO, 29, W«t Strength in Paper and Paperboarcl, Technical Association of the Pulp qnd. Paper Industry (New York, 1965), The most usefti wet strength resin* have generally been cationic in charftctcr. For permanent wet strength generation, polyBmidft-epjchlorohy^rin resins are cstfooio wet strength resins that have been found to be of particular Utility, Suitable types of such resins are describedhin U,S, Patent No. 3V?00,623 (Kcimi, issued October 24, '^972, and U,S, Patent No, (Keim), issued November 13, 1973. both of which are incorporated by reference. One commercial source of a useful pqlypmjde^pichlarohydrm wsiri is Hercules, Inc. of Wilmington, Delaware, v/Wcd markets such resins under the mart: Kymene® 557H- Polyacrylamide rcsing have ajso been found to be of utility as wet strength resins. These resins are described ia U.$, Patent Nas, 3,55 Cyanamid Co, of Stamford, Connecticut, which market* on* such resin under the mark Pirez®631NC. • ' Still other water-soluble catipnio resins finding utility wet strength resins are urea formaldehyde and rnelwnine formaldehyde resins, The more common functional groups of these polyfunctiotnl resins ire nitrogen containing groups such as ammo groups and methylol groups attached to nitrogen, Polyethylenjraino type resins can also find utility in the present invention, In addition, temporary wet strength resins such as C&ldaa 10 (manufactured 'by Japan Carlit), CoBcmd 1000 (manufactured by National Starch and Chemical Company), and Pare? 750 (manufactured' by American CyanarrUdc Co,) can be used in the present invention. It is to be understood that the addition of chemical compounds such as the wet strength and temporary wet strength resins discussed above to the pulp furnish is optional and is not necessary for the practice of the present invention. In addition to wet strength additives, it can also be desirable to include in the papermaking fibers certain dry strength and lint control $d.ditiveg itnown in the art- In this regard, starch binders have aeon found to bs particularly suitable, In addition to reducing linting of the fibrous structure, low levels of Btarch binders also impart a modest improvement in the dry tensile strength without imparting stiffness that could result from A the addition of high levels of starch, Typically the,starch binder is included in (in amount such that it is retained at a level of from about 0,01 to about 2%. preferably from about 6.1 to about 1 %, by weight of the paper substrate, In general, suitable starch binder* for these, fibrous structures are characterized by water solubility, and hydrophilicity. Although It ia not intended to limit the scope of suitable starch binders, representative starch materials include corn starch and potato storch, with wftjty corn starch known indHstrjally cs aroipca. starch being particularly preferred. Araioca starch differs from common corn starch in that it is entirely arayiopccfUv whereas common com starch contains both aiuylopectin and amylose. V&riau*--unique characteristics of amioca starch are farther describe^ in "Atfiioca« The Staj-ch From Waxy Com," H. H. Schopmeyer, Food Industries, December 1945, pp. ] 06-108 (Vol. pp. 1476-1478). The starch binder can be in granular or dispersed form, the granular form being especially preferred. The starch binder is preferably sufficiently cooked to induce sweljing of the granules, More preferably, the starch granules we swollen, as by peaking, to a point just prior to dispersion of the starch granule. Such highly swollen starch granules shall be referred to as being "fully poo(cod." The conditions for dispersion in general cau vary depending upon the size of the starch granules, the .degree of cryrtallinity of tiie granules, and the amount of amylose present, Fully coo]cc,d amioca starch, for example, can bo prepared by heating an aqueous sluny of about 4% consistency of starch granules at about 190°F (about 88°C) for between about 3D and about 40 minutes. Other exemplary starch binders thai can bo used include modified cat ionic starches such as those modified to'have nitrogen containing groups, including amino groups and methylol groups attached to nitrogen, availably from .Natipnal Starch and Chemical Company, (Bridgewater, New Jersey^ that have previously b^en used as pulp furnish additives to increase wet anchor dry strength. Use of other binders auch as latexes, polyvinyl alcohol, thermoplastic binder fibers, and the liHe, may also be. used in forming fibrous structures of the present invention. IH. Pnper Products The fibrous substrates pf the present invention are particularly adapicd for paper products, or components of paper products, vyhich are to be disposed of after use. Accordingly, it »s w be understood thai the present invention \& applicable to a variety of paper products including, but not limited to, disposable absorbent paper products such as those used for household, body, or other cleaning applications. Exemplary paper products Jest Method -Sffiction. The following is a description of how fibrous structures are prepared from both modified (i.e., treated in accordance with the present invention) and unropdifed (i.e., untreated or control) fibers, The$e structures are then subjected to the physical tests ({,0,, zero span tensile, dry tensile, and bending modulus per uw5t dry tensile) described in the succeeding Section. Low Density handsheew are made essentially according to TAJPPt standard T2QS, with the following modifications which we believed tQ more accurately reflect the tissue manufacturing process. > (1) tap water, with no pH 'adjustment, is wscd; (2) the embryonic web Is formed in a 12 in, by 12 in. handsheet making apparatus on a monofilwnent polyester wire supplied by Appefton Wire Co., Appelton, W.l with the'followins specificstions: Size: 13 iS inch x, 13.5 inch Machine direction Wftrp Count:' 84 1 ,5 fibers/inch Cross direction W*rp pount: 76 ± 3.0 fibers/inch Warp sizfr/type: 0,17millimeters/9FU Shute size/type: (K17 millimetereWP-llO CaJiper; 0.01 6 ± 0,0005 inch Air permeability; 720 ± 25 cwbie feet/minute (3) the embryonic yveb is transferred by vaftuum from the monofilftment polyester wire to a monofjlament polyester papertnftking fabric supplied by Appclton Wire Co., Appalton, WI and dewatered by vacuum suction instead of pressing; Fabric specifications; Size: 16 inch x 14 inch Machine direction Warp Count; 36 ± ) fibers/ipch Cross direction Warp Count; ' 30*3 fibers/inch Warp size/type: Q,4QmiHim«ters/WP-87*l2A-W Shute size/type: 0,40iri)!|imeters/WP-801--j2A.W Calipcr: 0,0270 * Q,QQ1 inch Air permaftbility: 3P7 ± 25 cubic Sheet side to be monoplane' Transfer and dcwatertag details: ,iThe embryonic web and paperisakwg wire are placed on top of the fabric such that the embryonic web contacts the fabric. The trilayer (wirft, web, fabric with fabric side down) 19 then passed lengthwise across a 13 in. x 1/16 Ln. >Vide vacuum slot box with s 90 degree flare set at a peak gauge reading of approximately 4.0 in. of mercury vacuum. The rate of the trilayer passing across the vacuum slot should bs uniform at a velocity of 16 ±5 in./s (4) the sheet is then, dried on a rotary drum drier with a drying felt by passing the web and fabric between the felt and drum with the fabric against tho drum surface and again with a second pass with the web against The drum surface, Dryer specifications: Stainless sveel polished finish cylinder with internal steam heating, horizontally mounted, External dimensions: 17 inches length X 13 inches diameter Temperature: 230 ± 5 degrees Fahrenheit. Rotation spood: 0,90 ± 0,05 revolutions/minute Dryer felt: Endless, 80 inches circumference by 16 inches wide, No, I Felt tension:, As low and,even as possible without any slippage occurring between the felt and dryer drum and uniform tracking, (5) the resulting handshe.pt is )2 in. X 12 irii with a resulting target bws weight of ' • 16,5 ± 1 pounds per 3,000 ft2 and a target density of 0.15 ± O.OS g/cc, unless otherwise noted. Tho dry 12 in. X 12 in. handsheet of fibers is then conditioned prior to testing t, minimum of 2 hours in a conditioned room where the temperature is 73DF j 4"F (Z2.8BC ± 2,2»C) and the relative humidity is 50% ± J 0%, ~" ~~ It will be recognized that the rest methods described in this section require the making pf bandsheets following the specific procedure described above. Where a given product is in 4 form that' includes chemical additives or where the fibrous structure is subjected to meohanicaJ manipulation in generating the product* it is to be recognized, chat the detemiinarion of whether 'that product ifl within the scope of the present invention is made by forming handsbeets in accordance with flic- present description, and measuring the -, physical properties of those hwdsheets, not measuring The physical properties of the product itself. That is, the fibers used to construct the product are wed to make the handsheets as described; no application of additives or mechanical manipulation, aside from that discussed above, should occur, However, as discussed above, density measurements are mads on final products which have been mechanically treated, include desired chemical additives, etc. A, |^rv Tensile gfgrtcrth, Iticjex This test is performed on 1 in. 'by 6 in. (about 2.5 cm X ! 5,2 cm) strips of pnpcr according to TAPPI standard? T220 om-88 and T494 oro»$8 in a conditioned room whtfre the temperature is 73°F + 4°F (about 28"C ± 2,2° C) and the relative humidity Is 50°/a ± 1Q%. An electronic tensile tester (Intellect; U-STp, Thwing Albert Corp,, Philadelphia, PA.) la used and operated ar a crossroad speed of 4';in. per minute (about 10 cro p«r minO and a starting gauge length of 4 in. (about 10 ern). A minimum of n « 8 fests are performed on each paper sample, The resulting tens)le strength values recorded in g/in, arc divided by the average basis weight of the sample and converted to achieve the corresponding tensile index values in N^m/g. B. This test is performed on 1 In. by 4 in, (about 2,5 cm X 1 Q£ cm) strips of paper (Including handsheets as described above, as well as other paper sheets) in a conditioned room whore tho temperature is 73*F ± 4°F (about 2SDC + 2,26C) and the relative humidity is 50% ± 10%. A combination electronic/compressed »ir tester (Troubleshootcr, Pulmac Instruments International, Montpelicr, VD is used and operated at an air supply pressure of 100 psi, The jaws of the tester are IS nun in width and loaded to a clamping pressure of SO psi, The pressure required to break the strip width of 15 mm with a beginning jaw separation of zero is recorded in units of psi, (If the pressure reading is bc1aw..9,psi, two plies of the handsheet material ore combined and tested to obtain measurements within the capability of the instrument.) The pressure to break minus the zeroing pressure of the instrument is divided by the average basis weight of the sample and converted to obtain the dry zero span tensile index value in units of N*m/g- A minimum of n * 8 tests arc performed on each pulp sample, C. yef Zerjj %sn .Tepsi|eiIint|ejC This test is performed similarly to the Dry Zero Span Tensile Strength procedure with the following modifications: The dry J in. X 4 in. strip of paper is inserted between two Wet Sample Inserters supplied with the instrument containing three notch, cuts. The paper strip is wette4 at the center notch cut with a squirt bottle filled with 73*F ± 4aF (about 2S°C ± 2.2PC) distilled water via squirting a small amount of water next to the notch and allowing it to drain into the center notch (avoiding heavy spray pressure or touching the sample with the tip of the pottle), The sample and iasertore are then set into the head of the unit with the notches lining up with the jaw teeth and the test is run as described above. The pressure to break minus the zeroing pressure of the instrument is divided by the average basis weight of the sample and converted to obtain the wet zero span tensile Index value in units of N*m/g, A minimum of n n 8 tests are performed on each pulp sample. D- Bending This ,test is performed on 1 in. by 6 in. (about 2,5 om X 1 5,2 cm) strips of paper according to tho description below in ft conditioned room where the temperature is 73°F ± 4flF (about 28'C ± 2.2° C) and the relative humidity is 50% + 10% for a minimum of 2 hours prior to testing. A Cantilever Bending Tester such as described in ASTM Standard D I38S (Model 5010, instrument Marketing Services, Fairfield, NJ.) can be used and operated at a ramp angle of 41.5 ± O.S8 and a sample slide speed of 0-5 ± 0.2 in. per second (about 1,3 + 0,5 cm per second). A minimum of n = 16 tests are performed, on each paper sample from n =" 8 sample strips, i. Prom oue handsheet, carefully cut four I in. wide strips of sample 6.0 ± 0.1 inches in length in the *MD" direction. From a second handshcet of the same sample set, carefully cut four 1 in. wide strips of sample 6.0 + 0,1 inches in length In the "CD" direction. It is important that the cut be exactly perpendicular to the long dimension of the strip. The strip should also be free of wrinkles or excessive mechanical manipulation which^carr- impact flexUity. Mark the direction very lightly on one end, keeping the same surface of diesample up for all strips^ Later, the strips will be turned over for testing, thus it is important that ore surface of the'«trip,be clearly identified, however, it makes no difference wh'ieh surface of the sample is desisnated.as the upper surface. i if, Oper,atioQ The tester should fro placed on a bend), or table that is relatively ftcis of vibration, excessive heat, and air drafts- Adjust The platform $ horizontal as indicated by the leveling bubble and verify that the bend angle is at 41, 5 ±0.5°. ' '• Remove the wimple slide bar from the tpp'of the platform of thp bendmg tester, Plspe one of the test sample strips on the horizontal platform using oare to align the strip parallel with the movable slide. Align the sample exactly even with the vertical edge pf the tester whore me angular ramp is attached or where the *ero mark line is scribed on the .tester. Carefully place the sample slide back on top of the sample strip in the tester. The sample slide must be carefully placed so that the strip Is not wrinkled or moved from its initial position, Move the sample and sample slide at a rate of approximately of 0,5 ± 0.2 in. per second (about 1.3 £ 0,5 cm per second), toward the end of the tester to which the rsmp is attached, This can be accomplished with either a manual or automatic tester. Ensure that no slippage between the sample and movable slide occurs, As the sample slide bar and sample strip project over the edge pf the tesfer, thp sample sirip will begin to bend, or d,rape downward. Stop moving the sample slide bar the instant the leading edge of the sample strip falls level with the ramp edge. Head and record the overhang length from the linear scale to the nearest 0,5 millimeters. Record the distance the sample slide bar has moved in centimeters as overhang length. The test sequence is performed on the face and back of each sample strip for a total pf two readings per specimen. This in wm, gives a total of siMeen readings for each paper sample comprising 8 MP and 8 CO readings. The average overhang length is determined by averaging the sixteen results obtained on the paper sample. Avsrage Overhang Length » ^PLPf 16 results Bend length is oalcqjated by dividing average overhang length by twp. fiend Length *• ^ Calculate the flexural rigidity (G): where W is the sample basis weight in pounds/3000, eq, ft,, and C is the bending len«ih in ,cm. Results are expressed' in milligram fqrce*cm; In general, the flexural rigidity (stiffness) is1 highly dependent on sample thickness (calipcr). In order to compare samples of unequal cajiper, Bending Modulus is used AS the comparison means. Where Q is the FlwtiffaJ Rigidity of the sample (above) and I is the moment of inertia. Using standard techniques for plate theory, -the above aquation may be manipulated to give the more useful relationship: where Q is the Bending Modulus in Kg-forcc/cm2, G is the Floxural Rigidity (above in mg-force*om) t is the sample thickness (caliper) in mils (1/1000 inch), and 732 is a conversion The sheet stiffness is also dependantly related to dry tensile strength of the fibrous structure, Since it is desirable to produce samples with lower stiffness withoijt corresponding decreases in sheet strength, the ratio of Bending Modulus per unit dry tensile are reported. This enables samples of unequal tensile strength and calipcr 10 be compared with a greater softness potential realized at a lower ratio. The relationship is shown beiuw: Where M is the Bending Modulus/Dry tensile ratio jn units of I /cm7, Q is the Bending Modulus in Kg-force/cm* aod dry tensile is in units pf grams-force. fftatting Fibers Northern Softwood Kraft (NSK) pulp; •••' Standard Reference Material R495 Northern Softwood Bleached 'Kraft Pulp (U.S. Dept. of Commerce, National Institute of Standards end Technology, Gajthershurg, MD 20899), drylap form. Eucalyptus (Euc) pulp; Standard Reference Material 8496 Eucalyptus Hardwood Bleached Kraft Pulp (U.S, Dcpt. pf Commerce, National Institute of Standards and Technology, Gaithorsburg, MP 20899), in drylap form. Northern Hardwood Sulfite (NHS) pulp; Never drjed, bleached, m&ed hardwood acid bisulfite pulp (The Procter and Gamble Paper Products Company Mehoopany, PA). Totally Chlorine Free bleached via EOP bleaching to a 93,7, -0,5, 6,4 Hunter t, a, b, color. Southern Softwood Kraft (SSK) pulp: Buckeye Cellulose Corporation Memphis, TN type FF (Foley Fluff) fully bleached pulp comprised of Slash and loblolly pine in drylap form. B. ful After determining.^ pulp consistency, the above pulps are divided into multiple batches of approximately 30 grams bone dry fiber each and are diluted to 2,QOQ mL with room temperature distilled water. The fibers and wafer are then disintegrated for 50,000 revolutions in a TAPPI Standard Pulp Disintegrator (Model D-I11, Testing Machines Incorporated, Islondia, New York). After disintegration, the pulp slurry is quantitatively transferred and dewatercd in a Buchner funnel with filter paper. The resulting pwlp cake is peeled from the filter paper and the filter paper is rinsed over the caHe to retain extraneous fiber, The pqlp cake is then refrigerated until further testing outlined below for a maximum of one week. C. Eq^ymc Preparation , Refrigerated, concentrated liquid enzyme is diluted to a I or 2 % concentration (vol/vol) in an 80/20 mixture of distilled water and '1,2 propanediol and refrigerated until u&e; Carezyme® 5.0L or Celluclast® .1.5 L or Celluzyme® 0.7 T - aJ) available from Nova Nordtsfc, Bagsvaerd, Denmark • or Pergolasc A4Q, available from Cvb^, Greensboro, N.C,, are used. EXAMPLE, k ibers with Northern Softwood Kraft (NSK) pulp cakes from section E above are treated and made into 1 8 low density handshect samples (6 sheet? per sample) using the procedure outlined above. The coptrol NSK pulp is left unmodified and is diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions iaa TAPPJ Standard Desintigwtor before • handsheet making. Sample IA is an NSK pulp treated without enzymes: The fibers are treated at approximately 3yo,;con*istency. Distilled water preheated to 120°F is first mixed with 30 m'L of a 1% hexamethonium bromide solution (]% wt active chcmicaVwt dry fiber basis) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin1, Rochester, NY) in a 120"? water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven arid is then added to the dobonder/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour, Atthp find of the hour, the pulp slurry is quantitatively transferred ajid ringed with approximately 500 mL of distilled water and dewatcred in ?i puchner funnel with filter paper. The resulting pulp cake i$ then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPJ Standard Desintigrator before hojidshcet making. Sample IB is an NSK pulp fretted without enzymes: The fiber? are treated at approximately 3% Consistency, Distilled water preheated to J20°F is first mixed wt'lh. 90 mi of a 2% telTaethylammonium bromide solution (l0^ wt active chemical/wt dry fiber basis) for approximately IS seconds via a Ughtm'n,1® lab mixer (Lightning Rochester, NY) in § 12Q°F water bath. The unmodified pulp cako is preheated to approximately I20°F via a microwave ovwi and is then added to the debonder/wattt- mixture, The mixing rate of the Lvghtnin1® mixer is increased to achieve continuous turn over and agitation of the pu|p slurry and allowed to react for approximately 1 hour. At the'eod of the hour, the pulp slurry is quantitatively transferred and rinsed with approximately 500 mL of distilled water and dewatered in a Buchner funnel with filter paper, The resulting pwlp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 ravolutjons in a TAPPJ Standard Desiurigratof" before handsheet making. Sample 1C is anNSK pulp treated without enzymes; Th» fibers are treated at approximately 394 consistency. Distilled water preheated to 120CF is first mixed with 30 mL of a Wt I auryl trim ethyl ammonium chloride (Slierex Chemical Co, Witco Corp,, Greenwich, CT) (1% wt active chemio&l/wt dry fiber basis) for approximately IS seconds via a Lightnln'® lab mixer (Ughtoin1, Rochester, NY) in 4 120°F water bath. The unmodified pulp cake is preheated to approximately 120*F via a microwave oven and is then added to the delxwderAvater mixture. The mixing rate of the , Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and rinsed with approximately 500 rnL of distilled water and dewatered in a Buehner funnel with filter paper. The resulting pulp cake is then diluted to 2,000 mL with vap water, and disintegrated for 3,000 revolutions in a TAPPl • Standard Desiniigrator before handsheet making. Sample. ID is an NSK pulp treated without enzymes: The fibers are treated at approximately 3% consistency. Distilled water preheated to 120°F is first mixed with 10 mL of a 3% N-decyl-N,N-dimethyl&mine Q**fc (BsrJox® 10S - Lowsa, Inc. Fairlawn, N,J.) (1% wt N-decyl-N.N-dimethylarolne cxide/wt dry fiber basis) for approximately 15 seconds via a Lighmin1® lab mixer (Lightnin1, Rochester, NY) in a 120^ water bath, The unmodified pulp cake is,preheated to approximately 12Q"F via a microwave oven and is theD added to the debondor/water mixture. The mixing rate qf the LighmiiV© mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and rinsed with approximately 500 mL of riisiilled water and dewatered in a Buehner fynnel with filter pafcer, The resulting puip cake is then diluted to 2,000 nvL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Pesintigrator before handshcot making, Sample IB is made from.i NSK. pulp that is modified by the following process: The fibers are treated at approximately 3% consistency. pjgtUled water preheated to 120°F is first mixed with 30 mL of a 1% Carezyme® solution (\% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 ueeonds via a Lightnin1® lab mixer (Lightnin1, Rochester, NY) in a 120DF water bath. The unmodified pulp «ke is preheated to approximately 1SOT via a microwave oven and is then ad,clpdja the enzyme/water mixture. ^The mixing rate of the Lightnin'® mixer is increased to achievecontinuous turn over and agitation of the pulp slurry .and allowed to react for approximately 1 hour. At the end of the hour, the,pulp slurry ia quantitatively transferred and dewatsred in a Buchner funnel with filter paper,1' The modified pulp cake is then added to approximately 1,000 mL of A 100 ppm NaOCl (4 mL of Clorox®, available from The Clorox Co,, Oakland, CA) in 2,000 mL of distil led'Water) solution, mixed, and allowed to rtact for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the'modified pulp sluny is quantitatively transferred and rinsed with approximately 1,500 mL Pf distilled water and dewatcred in a Buchner funnel with filter paper. The resulting moilified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before hsndthoct making, Sample IF Is made from NSK pulp that is rnodified'by the following process: The fibers are treated at approximately 3% .consistency. Distilled water preheated to 120'F is fust rpixed with, 60 mL of a 1% Carezyme® solution (2% volume/wt addition ' of Carezyme® 5,0 L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lightnin', Rochester, >JY) in a 12QeF water bath, The unmodified pulp cake .is •preheated to approximately 120°F via a microwave oven and ja then added to the enayme/water mixture, The, mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and > sgjtatioa of the pulp slurry and allowed to renct for approximately 1 hour. At the end pf the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel With filter papfcr. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCl (4 mL of Clprox in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose, After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1.50Q mL of distilled water,and dewatered in »'Buchner funnel with filter paper- The resulting modified pulp cake is then diluted to 2,000 mL with' tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desirjtigrator before handsheet making. Sample 1G is made from NSK pulp that is modified by the following process: The fibers arc treated at approximately 3% starting consistency. Pistilled w.ater preheated to 1200F is first mixed with 30 mL of a 1% Carezyme® solution (1% volume/wt addition of Carozymc® 5.0 L on bone dry pulp) for approximately 15 seconds via' a Lightning lab niixer (Ugbtnm', Rochester, NY) in a 12Q°F water bath- The unmodified pulp cake is preheated to approximately J20°F via a microwave oven and is then added to * I t the enzyme/water mixture, The mixing rate of'the Lightnia'® mixor is increased, to achieve continuous turn over and agitation of the, pulp slurry and allowed to react for approximately l hour. At the end of the enzyme reaction period 30 m'L of & 1% (vvt/vpl) solution of hexamethooium bromide (Aldrich Chemical Company Milwaukee, WI catalogue No, 21,967-3) in distilled water is added,to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Sample 1H is made from NSKpulp that is modified,by the following process; The fibers are treated at approw'mately 3% starting consistency. Distilled water preheated to 120°F fc first mixed with 60 mt of a 1% Carezyme® solution (2% volume/wt addition of Carezyrae® 5.0 L on bone dry pulp) for approximately 15 seconds via a Ughtnin.1® lab mixer (UghtnhV, Rochester, NY) in,a J2Q°F water bath, The unmodified pulp cake is preheated to approximately 120aF via * microwave oven and is then added to the enzyme/water mixture. The mixing rate of,the Ughtnin'® mixer is increased to achieve continuous turn over and agitation of the. pulp slurry and allowed to react for approximately I hour. At the end of the enzyme reaction period, 30 mU of a 1% (wt/vol) solution of hexaroethonium bromide (Aldrich 'Chemical Company Milwaukee, Wf catalogue NO. 21,967-3) in distilled water is added to the enzymVpuJp slunry to achieve a 1% add-on level (wt active chemioal/wt dry fiber ba. sis) and alJoweH to continue mixing for a second, hour at 120°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Sample II is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120°F is first mixed with 30 mL of ft \% £arezyme® solution (1% volnme/wt addition of Carezyjne 5,0 L on bone dry p^Ipj for approximately 15 seconds via a Lightnin'® lab mixer (Ligbtajn', Rochester, NY) in, a 12QT water bath, The unmodified pulp cake is preheated to approximately 120°F via a, microwave oven and is then added w thr enzyme/water mixture. The mixing rate of the Lightnin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At th« end of the enzyme reaction period, 30 mL of a* 1 %j£vt/vol) solution of tetraethylammonium bromide (Aldrich Chemical Company Milwaukee, W7catalogue No. 14,002-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on Jeve) (wt active chemipal/wt dry fiber basis) and allowed tp continue mixing for a, second hour at 120*F. At the end of the second', ,hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 roL of a )00 ppm NaOCI (4 ml of CJorox® in 2,000 mL of distilled water) solution, mixed, and allowed.'to react for a minimum of 5 minutes* at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 ml. of distilled water and dewatered in a Buchner funnel with filter paper, The resulting modified pulp cako is then diluted to 2,000 mL with top water and disintegrated for 3,000 revolutions in a TAPPI Standard Pesintigrator before hancteb'eef making, Sample l J is made from pulp that is modified by the.follpwina process: The pulp cake is treated at approximately a 3% Starting consistency, Distilled water preheated to 120°F is first mixed with 30 m,t of the 1% Carezyme® solution (1% vofum«/wt addition of Carezyine® 5,0 L on bone dry pulp) for approximately 15 seconds via a Lightnin' lab mi?ter (tigbmW, Rochester,'-NY) in a 120°F water bath. Tho unmodi.fied pulp oake is prehpaM to approxim^tejy 120°P via ft microwave oven and is then added to the enzyme/water mixture, The mixing rate of thu pulp/enzyme slqrry is increased to achieve continuous turn over and agitation and allowed to react for approximately 1 hour. At the end of tho enzyme reaction poripd, 30 mL of a 1% (wt/vq!) solution of lauryl trimethyl ammonium chloride1 (Shores Chemical Cp, Witco Corp., Greenwich, CT) in distilled water is added to the cnxym«5/pulp shiny to achieve a 1% add¬on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120"F. At the end of the second'hour, the pulp slurry is quantitatively transferred and dewatercd in a Buchncr funnel with .filter paper, The modified pulp cake is thon added to approximately 1,000 mL of a 10Q ppm NftOCI (4 mL of Clorpx® in 2,QOQ mL of distilled water) solution, mixed, and allowed,to react for» minimum of 5 minutes at room temperature to quench any further enzyme reactions with thp cellulose, After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and delvatered in a Bwchner funnel with filter paper, The resulting modified pulp cake is then diluted to 2,000 mL with tap water and •-•"'-rrV. disintegrated for 3,000 revolutions in a. TAPPI Standard Deiwtigrstor before handshcet making. Sample. IK is made from, pulp that is modified by the following process; The pulp cake is treated at approximately a 3% starting consistency, Distilled water preheated to J20°F is first mixed \vjth 3Q m,L pf the 1% Carezyrne® solution (1% volume/wt addition of Carezyme® 5,0 L on bone dry pulp) for approximately 15 seconds via a Lightnin® lab mixer (Ljghtnirt1, Rochester; NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture, The mixing 'rate of the pulp/enzyme slurry is increased to achieve continuous turn over and agitation and allowed to react for approximately I hour. At the end of the enzyme reaction period, 30 mL of a \% (wt/vof) solution of triethanolaminc (Dow Chemical Co, Midland Ml) fn distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 12QaF. At the end of the second hour, the pulp slurry is quantitatively transferred arid dfiwatered in a Buchner rXmncl with filter paper. The modified pulp calce is then added to approximately l.OOQ mL of a 100 pptn NaOCl (4 mL of C)orox Sample IL is made from pulp that is modified by the following process; The pulp cake is treated, at approximately,^ 3% starting consistency. Distilled water preheated to 12Q°F is first mixed with 30 mL of the 1% Carezyme® solution 0% volume/wt addition of Carezyme® 5,0 L on bone dry pi4lp) for approximately 15 seconds via a Lighmin® lab mixer (Lighmin1, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is| preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture, The mining rate of the pulp/onzyme slurry is increased to achieve continuous turn over and agitation and allowed to react for approximately 1 hour.' At the end of the enzyme reaction period, the pH of the enzyme/pulp slurry is then adjusted to pH 7,5 with the addition ofO.pl N NaOH. 10 ml- of a 3% (wt/vol) solution of N-Jecyl-N.N-dimethylamine oxide (Barlox® IDS - Lanza, Inc. Fairlawn, N^O «n distilled water is added to the enzyme/pulp slurry to achieve aT/a add¬on level (wt active chemical/wr dry fiber basis) and allowed to continue mixing for a second hour at 1200F, At the end of the second'hour, the slurry of modified fibers is acidified to pH 3,8 with HC], The modified pulp slurry is quantitatively transferred and rinsed with approximately 500 mL of distilled water and dewatered in a Buchner funnel with filter paper, The resulting modified pulp cake is then diluted to 2,000 mL with tup water and disintegrated for 3,000 revolutions in'a;.,TAPPI Standard Desintigrator before handsheet making Sample 1M is made from pulp that is modified by the following process: The pulp cake is treated at approximately, a 3% storting consistency. Distilled water preheated to 120°F Is first mixed with 30 mi, of the \% Carezyme® solution (1% volume/wt addition of Carezymei® S.O L on bone dry pulp) for approximately 15 seconds via a Lightnin® lab mixer (Lightning Rochester^ NY) in a 120°F.water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the pulp/enzyme slurry is increased to achieve continuous turn over toad',agitation and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of fl 1% (wt/vol) solution of lauryl trlmethyl rnnmonlurn chloride-(Sherex; Chemical Co, Witco. Corpr, Greenwich, CT) in distilled water is added to the enzyme/pulp slurry to achieve « l% add¬on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for SS minutes at 120°F. After mtaing of the lauryl trimetbyl ammonium chloride and the modified pulp slurry, 15 mL of a 2% solution of carboxymothyl cellulose (Aqueilon Company, Wilmington, DE) (1% wt active oherruca|/wt dry fiber basis) is added and allowed to continue mixing for S minutes, The slurry of modified fibers is then made directly into low density handsheets without filtering* quenching or disintegration. Sample IN is made from pulp that is modified by the following process; Three unmodified pulp cakes prepared from section D nbove are treated et approximately a 5p/o consistency In a Quantum Mark III high intensity lab mixer, Diluted water preheated to 120°F is first miwd with 45 mL of a 2% Carezyme® solution (1% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 10 seconds and transferred 'to the mixing vessel which has been programmed to maintain 120°F i , temperature. The unmodified pulp cakes are preheated to approximately J2Q°F via. a microwave oven and are then added to the enzymeAvater mixture. After the lid is secured to the top of the vessel,' the mister shaft is then engaged to mix at * rate of appwximately 1,200 RPM (high intensity mixing) for IQ seconds' and then stopped- For the remainder of the how, mixing at 1,200 RPM for 10 seconds occurs every 10 minutes. Ai the end of the enayrne reaction period, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with cheesecloth to retain as much material ns possible. The resulting pulp cake is pepkd from the cheesecloth and IP then added to approximately 3nOQO mL of a JOQ ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react fpr a, minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the pulp slurry is quantitatively transferred and dewatered in a Puchner funnel with cheesecloth to retain as much material as possible. The cake is theti rinsed with approximately 1,300 mL of distilled water and dewatered, The resulting pulp cake is peeled from the cheesecloth and a sample corresponding to 30 bone dry grams is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet , making. Sample 1O is made from pulp that is modified by the following process; Six unmodified pulp cakes prepared from section B above are treated' at approximately a J0% consistency in a Quantum Mark IU high intensity lab mixer. Distilled water preheate-d to 120eF Is first mixed with 90 mL of a 2% Carezyme® solution (1% volume/wt addition of Carezyroe® 5.0 L on,'bone dry pulp) for approximately 10 seconds and transferred to the mixing vessel which has been programmed to maintain 120°F temperature. The unmodified pulp cakes are'preheated to approximately 120«F via a microwave oven and arc then added to the enzyme/water mixture. After the lid is secured to the top of the vessel, the mixer shaft is then engaged to mix at a rafc of approximately l,200. RPM (high intensity mixing) for 10 seconds and then stopped, For the remainder of the hour, mixing at 1,200 RPM for 10 seconds occurs every 10 minutes for a total of 70 seconds. At the end of the enzyme reaction period, the pulp slurry is quantitatively transferred and dewatered in a Buchner ftmjicl with cheesecloth to retain sis much material as possible. The resulting pulp cake is peeled from the cheesecloth and is then added to approximately 6,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allawed.to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the pulp slurry is quantitatively transferred and dewatered in a Bucbner funnel with cheesecloth to retain as much material as possible, The cake is then rinsed with approximately 3,000 mL of distilled water a»d dewatcrcd. The resulting pulp cake, is peeled frpm the cheesecloth and a sample corresponding to 30 bone dry grams is {hen diluted to 2,000 mL with tap water and disintegrated for 3.000 revolutions in a TAPPI Standard Desintigrator before handsheet making. . 1 Sample 1P is made from pulp that is modified by the following process: Eight unmodified pulp cakes prepared from section B above are treated at approximately a 13,3% consistency in a Quantum Mark III high intensity lab mixer. Distilled water preheated to 120°F is first mixed with 135 mL of a 2% Carezyme® solution (1.12% volume/wt addition of Carezyme® 3,0 L on bone dry pulp) for approximately 10 seconds and transferred to the .mixing vessel which has beta programmed to maintain 120°F temperature. The unmodified pulp cakes are preheated to approximately HOT via a microwave oven and are then added to the enzyme/water mixture. After the lid is secured to the top of the vessel, the mixer shaft is then engaged to mix at a rate of approximately 1,200 RPM (high intensity mixing) for !0 seconds and then stopped. For the remainder of the hour, mixing at 1,200 RPM for 10 seconds occurs every 10 minutes. At the end of the enzyme reaction period, the pulp slurry is quantitatively transferred and dewatered io a Buchner funnel with: cheesecloth to retain as much material as possible. The resulting pulp cake is peeled from the cheesecloth and is then added to approximately 6,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose, After quenching, the pulp slurry is quantitatively transferred and dewatered in a Buclmer funnel with cheesecloth to retain as much material as possible. The cake is then rinsed with approximately 5,000 mL of distilled water and dewatered. The resulting pulp cake is peeled from the cheesecloth and a sample corresponding to 30 bone dry grams is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handshect making. Sample 1Q is made from pulp that is modified by the following process; Six unmodified pulp cakes prepared fftm section B above are treated at approximately a 10% consistency in a Quantum1 Mark 111 high intensity lab mixer. Distilled water preheated to 120°F is first mixed with 90 mL of a 2% Carezyme® solution (1% volume/wt addition of Carezyme® 5.0 L on.bone dry pulp) for approximately 10 seconds and transferred to the mixing vessel which has been programmed to maintain 120°F temperature. The unmodified pulp cakes are preheated to approximately, UO°F via a microwave oven and are then added to the enzyme/water mixture. After the lid is secured to the top of the vessel, the mixer shaft is then engaged to mix at a rate of approximately 1,200 RPM (high intensity mixing) for 10 seconds. After the initial high intensity mixing step, low intensity mixing at 120 RPM for 10 seconds duration is accomplished every 2 minutes for the remainder of the hour except at times of 25,40, and 50 minutes where high intensity mixing at 1,200 RPM is done at 20 second durations. At the end of the enzyme reaction period, a combination of 40 mL of a 4% (wt/vol) emulsion (0.9% add-on to dry fibers) of dihdrogcnated tallow dimethyl ammonium methyl sulfate (Sherex Chemical Co, Witco Corp., Greenwich, CT) in distilled water and SO mL of a 4% (wt/vol) solution (1.1% add-on to dry fibers) of lauryl trimethyl ammonium chloride (Sherex Chemical Co, Witco Corp., Greenwich, CT) in distilled water and is added to the enzyme/pulp slurry to achieve a 2% total add-on level (wt active chemical/wt dry fiber basis). After the lid is again secured to the top of the vessel, the mixer shaft is then engaged to mix at a rate of approximately 1.200 RPM (high intensity mixing) for 10 seconds and then stopped. For the next 30 minutes, mixing at a rate of approximately 1,200 RPM for 10 seconds occurs every 3 minutes. At the end of the treatment period, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with cheesecloth to retain as much material as possible. The cake is then rinsed with approximately 3,000 mL of distilled water and dewatered. The resulting pulp cake is peeled from the cheesecloth and a sample corresponding to 30 bone dry grams is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before hand sheet making. Table ! gives the results of the density, dry tensile index, dry and wet zero span tcnsiles indices, and DT/DZST ratios of the low density handshee: samples made. It can be seen from the Table that enzyme modification of the fibers with Carezyme® results in substantial reduction of the dry zero span tensile index (DZST) of the NSK, fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet sample produced from unmodified control fibers. The addition of chemical debonders to the enzyme modified fibers further reduces the D2ST. Furthermore, high intensity mixing combined with the enzyme treatment, as well as both enzyme and dtibonder treatment steps, results in even greater reductions in DZST without negatively impacting sheet tensile. (Table Removed) Cz = Carezyme® 5.0 L HMB " hexamethoniiun bromide TEAB = wtraethylaminoniuin bromide LTAC = lauryl trimethylammonimn chloride TEA = triethanolamine BlOS-Barlox® 1QS CMC = carboxymethyl cellulose HIM = high intensity mixing k consistency DTDMAMS - dihydrogenated tallow dimethyl ammonium methyl sulfate Not an example of the present invention. EXAMPLE 2: Treatment of NSK_Fibers with.Cellu.cl.as.t@ Northern Softwood Kraft (NSK) pulp cakes from section B above are treated and made into 4 low density handsheet samples (6 sheets per sample) using the procedure outlined above. The control NSK pulp is the same as in Table 1. Sample 2A is made from NSK pulp that is modified by the following process: The fibers arc treated at approximately 3% starting consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120°F, is first mixed with 30 mL of a 1% Celluoiast® solution (1% volum«/wt addition, of Celluclast® 1.5 L on bone dry pulp) for approximately 1S seconds via a Lightnin'® lab mixer (Lightnin1, Rochester, NY) in a 1206F water bath. The unmodified pulp cake is preheated to approximately 120°F via a. microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPl Standard Deslntigrator before handsheet making. Sample 2B is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% consistency in a SO millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120aF, is first mixed with 60 mL of a 1% Celluclast® solution (2% volume/wt addition of Celluclast® 1.5 L on bane dry pulp) for approximately 15 seconds via a Lighmin'® tab mixer (Lightnio1, Rochester, NY) in a 120'F water bath. The unmodified pulp cake is preheated to approximately 120*F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin' The fibers are treated at approximately 3%,consistency in a 50 millimotar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120"F, is first mixed with 30 mL of a 1% Celluclast© solution (1% volume/wt addition of Celluclast® 1.5 L on bone dry p«lp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin', Rochester, NY) in a 120aF water bath. The unmodified pulp cake is preheated to approximately 120*F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of a \% (wt/vol) solution of hexamethonium bromide (Aldrich Chemical Company Milwaukee, Wl catalogue No. 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Sample 2D is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3%,consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4,7. The buffer solution, preheated to 120°F, is first mixed with 60 mL of a 1% Celluclast® solution (2% volume/wt addition of Celluclast® 1.5 L on bone dry pulp) for approximately IS seconds via a Lightnin'® lab mixer (Lightnin1, Rochester, NY) in a 120"F water bath. The unmodified pulp cake is preheated to approximately 120BF via a, microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour At the end of the enzyme reaction period, 30 mL of a 1% (\vt/vol) solution of hexamethonium bromide (Aldrich Chemical Company Milwaukee, WI catalogue No, 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and aJlowed to continue mixing for a second hour at 120°F. At the end of the second, hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Table 2 gives the results of the density, dry tensile index, dry and wet zero span tensites indices, and DT/DZST ratios of the low density handsheet samples made. It can be seen from the Table that enzyme modification of the fibers with Celluclast® results in substantial reduction of the dry zero span tensile index (DZST) of the NSK fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet sample produced from unmodified control fibers. The addition of chemical dcbonders to the enzyme modified fibers further reduces the DZST. Table 2 ' (Table Removed) CC = Celluclast® l.SL HMB = hexamethonium bromide Not an example of the present invention Treatment of NSK Fibers with Celluzvme® or Northern Softwood Kraft (NSK) pulp cakes from section B above are treated and made into 2 low density handsheet samples (6 sheets per sample) using the procedure outlined above. The control TSSK pulp is the same aa in Table 1 , Sample 3 A is made from NSK pulp th*t is modified by the following process: The fibers are treated at approximately 3% consistency. Distilled water preheated to 120eF is first mixed with ].89g of Celluzyme® 0.7 T (6.3% wt/wt addition of Cclluzyme® 0.7 T on bone dry pulp) for approximately IS seconds via a LighUiin'® lab mixer (Lightmn1, Rochester, NY) in a 120°F water bath, The unmodified pulp cake is preheated to approximately 12Q°F via a microwave oven and is then edded to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buctiner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 ml* of a 100 ppm NaOCl. (4 mL of Clorojc® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatared in a Buchner funaal with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 3B is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% consistency in a 50 mill/molar buffer solution of sodium acetate and acetic acid of pH 4.7, The buffer solution, preheated to 120°F, Is first mixed with 30 mL of a 1% Pergolase1® solution (1% volume/wt addition of Pergolase® A40 on bone dry pulp) for approximately 1 5 seconds via a Lightnin'© lab mixer (Lightnin', Rochester, NY) in e. 120T water bath. The unmodified pulp cake is preheated to approximately 120SF via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the LightnirV® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately I hour. At the end of the hour, the pulp slurry is quamitativdy "transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately \,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the c«llulos«. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Table 3 gives the results of the density, dry tensile index, dry and wet zero span tensiles indices, and DT/DZST ratios of the low density handsheet samples made. It can be seen from the Table that enzyme modification of the fibers with Celluzyms® and Pergolase® results in substantially reducing the dry zero span tensile index (DZST) of the NSK fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet sample produced from unmodified control fibers. Table 3 (Table Removed) Not an example of the present invention EXAMPLE 4; Tjeatigent of Eucalyptus Fibers with Carezymc® Eucalyptus (Euc) pulp cakes from section B above are treated and made into 5 low density handsheet samples (6 sheets per sample) using the procedure outlined above. The control eucalyptus putp is left unmodified and is diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 4A is roade from eucalyptus pulp that is modified by the following process: The fibers are treated at approximately 3% consistency. Distilled water preheated to 120T is first mixed with 30 mL of a 1% Carezyme® solution (1% volume/wt addition of Carezyme® 5,0 L on bone dry pulp) for approximately 15 seconds via a Ligbtnin'® lab mixer (Lightnin', Rochester, NY) in a I20eF water bath. The unmodified pulp cake.is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lighmin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCJ (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately !,SOO mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desmtigrator before handsheet making. Sample 4B is made from eucalyptus pulp that is modified by the following process; The fibers are treated at approximately 3% consistency. Distilled water preheated to 120°F is first mixed with 60 mL of a 1% Carezyme® solution (2% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15. seconds via a Lightnin'® lab mixer (Lightnin1, Rochester, NY) in a 120aF water bath. The unmodified pulp cake is preheated to approximately I208F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in & TAPPI Standard Desintigrator before handsheet making. Sample 4C is made from NSK. pulp that is modified, by the following process; The fibers are treated at approximately starting consistency. Distjllgd water preheated to 120°F is first mixed with 30 mL of a W Cqrezyme® solution (1% volume/wt addition of Carezyme® 5,0 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lighmin1, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated TO approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of a 1% (wt/vol) solution of hexamethonium bromide (Aldrich Chemical Company Milwaukee, WI catalogue No. 21.967-3) in distilled water is added to the enzyme/pulp slurry to achieve a. \% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing Cor a second hour at 120°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Sample 4D is made from eucalyptus pulp that is modified by the following process; The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120°F is first mixed with 60 mL of a 1% Carezyme® solution (2% volume/wt addition of Carezyme® 5,0 L on bone dry pulp) for approximately IS seconds via a Lightnin1® lab mixer (Lighinln', Rochester, NY) in a |20°F water bath. The unmodified pulp cake is preheated to approximately 1206F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of Uie Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of a 1% (wt/vol) solution of hcxamethonium bromide (Aldrich Chemical Company Milwaukee, WI catalogue No, 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120'F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Sample 4E is made from eucalyptus pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120°F is first mixed with 30 m.L of a 1% Carezyme® solution (1% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin', Rochester, NY) in:a 120°F water bath. The unmodified pulp cake is preheated to approximately I20°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightninr® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of a iy«, solution of tetraethytammonium bromide (Aldrich Chemical Company Milwaukee, WI catalogue No, 14,002-3) in distilled water is added,to the enzyme/pulp slurry to achieve & 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching, or disintegration. Table 4 gives the results of the density, dry tensile index, dry and wet zero span tensiles indices, and DT/DZST ratios of the low density handsheet samples made. It can be seen from the table that enzyme modification of the fibers with Car«zyrne results in substantial reduction of the dry zero span tensile index (DZST) of the hardwood eucalyptus fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet sample produced from unmodified control fibers. The addition of chemical debonders to the enzyme modified fibers further reduces the DZST. Table4 (Table Removed) *: Cz •= Cwrezyme® 5.0 L HMB = hexamethonium bromide TEAB tetraethylammonium bromide **: Not an example of the present invention. Treatment of Eucalyptus Fibers with Celluclast® Eucalyptus (Euc) pulp cakes from section B above are treated and made into 4 low density handsbeet samples (6 sheets per sample) using the procedure outlined above. The control eucalyptus pulp is the same as in Tabte 4. Sample 5A is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to I20°F, is first mixed with 30 mL of a 1% Celluclast ® solution (IV* volume/wt addition of Celluclast® 1.5 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightning Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lighmin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper, The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 5B is made from NSK pulp that is modified by the following process; The fibers are treated at approximately 3% consistency in a SO millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120°F, is first mixed with 60 mL of a 1% CeJlucJast solution (2% volume/wt addition of Celluclast® 1 .5 L on bone dry pulp) for approximately 15 seconds via a Lightaifl'® lab mixer (Lightnin1, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lighrnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour.. At the end of th^ hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 300 ppm NaOCI (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 5C is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120*?, is first mixed with 30 mL of a 1% Celluclast ® solution (1% volume/wt addition of Celluclast® 1.5 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin', Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of a }% (wt/vol) solution of hexamethonium bromide (Aldrich Chemical Company Milwaukee, WI catalogue No. 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1 % add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Sample 5D is made from NSK pulp that is modified by the following process; The fibers are treated at approximately 3% consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120°F, is first mixed with 60 mL of a I'/o Celluclast ® solution (2% volume/wt addition of Celluclast® 1.5 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lighoiin1, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately I20°F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30-mL ofa l°/« (wt/vol)-solution of hexamethonium bromide (Aldrich Chemical Company Milwaukee, Wl catalogue No. 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemicai/wt dry fiber basis) and allowed to continue mixing for a second hour at 12Q°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Table 5 gives the results of the density, dry tensile index, dry and wet zero span tensiles indices, and DT/DZST ratios of the low density handsheet samples made. It can be seen from the table that enzyme modification of the hardwood eucalyptus fibers with Celluclast® results in substantially reducing the dry zero span tensile index (DZST) of the NSK fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet sample produced from unmodified control fibers. The addition of chemical debonders to the enzyme modified fibers further reduces the DZST, Tables (Table Removed) *: CC^Celluclast®1.5L HMB - hexamethonlum bromide Not aa example of the present invention. EXAMPLE 6: Treatment of Euclytus Fibers with Eucalyptus (Euc) pulp cakes from section B above are treated and maejelrito one low density handsheet samples (6 sheets per sample) using the procedure outlined above. The control eucalyptus pulp is the same as in Table 4. Sample 6A is made from Eucalyptus pulp that is modified by the following process: The fibers are treated at approximately 3% consistency. Distilled water preheated to 120*F is first mixed with l,89g of Celluzyme® 0.7 T (6.3% wt/wt addition of Celluzyme® 0.7 T on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lighmin1, Rochester, NY) in a 120^ water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately I hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatere4 in a Buchner funnel with filter paper, The resulting modified pulp cake is then diluted to 2,000 ml with up water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Tjble6 (Table Removed) *: Not an example of the present invention EXAMPLE?: Treatment of Northern H«rdyood_Sulfite fNHS) with Carezvmf® Northern Hardwood Sulfite (NHS) pulp cakes from section B above are treated and made into 3 low density handsheet samples (6 sheets per sample) using the procedure outlined above, The control NHS pulp is left unmodified and Is diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 7A is made from NHS pulp that is modified by the following process: The fibers are treated at approximately 3% consistency. Distilled water preheated to 120" F is first mixed with 30 mL of a 1% Carezyme® solution (1% volum«Avt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lightnin1, Rochester, NY) in a 120*F water bath. The unmodified pulp cake is preheated to approximately 120*F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Ligbmin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 ml with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. « Sample 7B is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120*F is first mixed with 30 mL of a \% Carezyme® solution (1% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lightnin', Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120'F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of a 1% (wt/vol) solution of hexamethonium bromide (Aldrich Chemical Company Milwaukee, WI catalogue No. 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120°F. At the end of the second hour, the slurry of modifiedlfbeTs is made directly into low density handsheets without filtering, quenching or disintegration. Table 7 gives the results of the density, dry tensile index, dry and wet zero span tensiles indices, and DT/DZST ratios of the low density handsheet samples made. It can be seen from the table that enzyme modification of the fibers with Carezyme® results in substantially reducing the dry zero span tensile index (DZST) of the NHS fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet sample produced from unmodified control fibers. The addition of chemical debonders to the enzyme modified fibers further reduces the DZST. Table 7 (Table Removed) * Cz = Carezyme® S .0 L HMB = hexamethonium bromide **: Not an example of the present invention. EXAMPLES: Treatment of Northern Hardwood Suifite with-CellqcJast® Northern Hardwood Suifite (NHS) pulp cakes from section B above are treated a/id made into 4 low density handsheet samples (6 sheets per sample) using the procedure outlined above. The control NHS pulp is the same as in Table 7. Sample 8A is made from NHS pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency in a SO millimolar buffer solution of sodium acetate and acetic acid of pH 4,7, The buffer solution, preheated to 120*F, is first mixed with 30 mL of a 1% Celluclasi® solution (l«/o volume/wt addition of Celluclast® 1.5 L on bone dry pulp) for approximately 15 seconds via a Lighinin1® lab mixer (Lightnin', Rochester, NY) in a I20°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin'® mixer is increased-tcrrchieve continuous rum over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of disrilled waterXsolution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose, After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample SB is made from NHS pulp that is modified by the following process: The fibers are treated at approximately 3% consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120°F, is first mixed with 60 mL of a 1% Celluclast ® solution (2% volume/wt addition of Celluclast® 1,5 I, on bone dry pulp) for approximately 15 seconds via a Lighmin'® lab mixer (Lightnin', Rochester, NY) in a 120°F water bath, The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 pprn NaQCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper, The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPJ Standard Desintigrator before handsheet making. Sample 8C is made from NHS pulp that is modified by the following process: The fibers are treated at approximately 3% consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120°F, is first mixed with 30 mL of a 1% Celluclest ® solution (1% volume/wt addition of Celluclast® 1.5 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin1, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately \ hour. At the end of the enzyme reaction period, 30 mL of a 1% (wt/vpl) solution of hexamethonium bromide (Aldrich ChemicaJ Company Milwaukee, Wl catalogue No. 21,967-3) in distilled water is added to the enrym&'pulp slurry to achieve a 1% add-on level (wt active chemicaJ/wt dry fiber basis) and allowed to continue mixing for a second hour at 120"F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration, Sample 8D is made from NSK puip that is modified by the following process: The fibers are treated at approximately 3% consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120SF, is first mixed with 60 mL of a 1% Celtuclast ® solution (2% volume/wt addition of Celluclast® 1.5 L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (LightnuY, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120*F via a microwave oven and is then added to the enzyme/buffer mixture, The mixing rate of the Lightnin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of a 1% (wt/vol) solution of hexamethonium bromide (Aldrich Chemical Company Milwaukee, V/I catalogue No. 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120*F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Table 8 gives the results of the density, dry tensile index, dry and wet zero span tensiles. indices, and DT/DZST ratios of the low density handsheet samples made. It can be seen from the table that enzyme modification of the fibers with Celluclaat® results in substantially reducing the dry zero span tensile index (DZST) of the NHS fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet sample produced from unmodified control fibers. The addition of chemical 'debonders to the enzyme modified fibers further reduces the DZST. (Table Removed) *: CC-Celhiclart»I.3L HMB - hexamethoniutn bromide **: Not an example of the present invention EXAMPLE 9: Treatment of Southern Softwood Kraft Fibers with Carezvme® Southern Softwood Kraft (SSK) pulp cakes from section B above are treated and made into 3 low density handsheet samples (6 sheets per sample) using the procedure outlined above. The control SSK pulp is left unmodified and is diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Deaintigrator before handsheet making. Sample 9A is made from SSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120eF is first mixed with 30 mL of a \% Carezyme® solution (1% volume/wt addition of Carezyme® 5,0 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (LightnifV, Rochester, NY) in a 120*F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rat* of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour, At the end of the enzyme reaction period, 30 mL of a l% (wt/vol) solution of hexamethonium bromide (Aldrich Chemical Company Milwaukee, Wl catalogue No, 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 120°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration-Sample 9B is made from NSK pulp that is modified by the following process: The fibers, are treated at approximately 3% starting consistency, Distilled water preheated to 120SF is first mixed with 60 mL of a 1% C&rezyme® solution (2H volume/wt addition of Carezyme® 5,0 L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lighmin', Rochester, NY) in a 1208F water bath. The unmodified pqlp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lighmin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, 30 mL of a 1% (wt/vol) solution of hexamethonium bromide {Aldrich Chemical Company Milwaukee, Wl catalogue No. 21,967-3) in distilled water is added to the enzyme/pulp slurry to achieve a 1% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for a second hour at 320°F. At the end of the second hour, the slurry of modified fibers is made directly into low density handsheets without filtering, quenching or disintegration. Table 9 gives the results of the density, dry tensile index, dry and wet zero span tensiles indices, and DT/OZST ratios of the low density handsheet samples made. It can be seen from the table that enzyme modification of the fibers with Carezyme® followed by debonder treatment results in substantially reducing the dry zero span tensile index (DZST) of the SSK fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet sample produced from unmodified fibers. (Table Removed) *: Cz = Carezyme® S .0 L HMB *» hexamethonium bromide **: Not an example of the present invention. EXAMPLE 10: Treatment of NSK Fjbers aad^FibrojAs Structures. Having Improved Flexibility Northern Softwood Kraft (NSK) pulp cakes from section 8 above are treated and made into 15 low density handsheet samples (6 sheets per sample) using the procedure outlined above. The control NSK pulp is left unmodified, diluted to 2,000 mL with tap water, and disintegrated for 3,000 revolutions in a TAPPI Standard Disintegrator before handsheet making. Sample IDA is made from NSK. pulp that is modified by the following process: The fibers are treated at approximately 3% consistency. Distilled water preheated to 120°F is first mixed with 7.5 mL of a 2% Carezyme® solution (0,5»/» vohime/wt addition of Caresyrae® 5.0 L on bone dry pulp) for approximately IS seconds via a Lightnin1® lab mixer (Lightnin1, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120'F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaQCl (4 mL of Ctorox®, available from The Clorox Co., Oakland, CA) in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Disintegrator before handsheet making. Sample 10B is made from NSK. pulp that is modified by the following process: The fibers are treated at approximately 3% consistency. Distilled water preheated to 120"F is first mixed with 22.5 mL of a 2% Carezyme® solution (1.5% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lightnin', Rochester, NY) in a 120*F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaQCl (4 mL of Clorox in 2,000 mL~e£distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample IOC is made from NSK. pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency in a 50 millimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120°F, is first mixed with 7.5 mL of a 2% CeUuclast® solution (0.5% volume/wt addition of CeUuclast® 1.5 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin', Rochester, NY) in a 120*F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The modified pulp cake is then added to approximately 1,000 mL of a 100 ppm NaOCI (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of 5 minutes at room temperature to quench any further enzyme reactions with the cellulose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately J,500 mL of distilled water and dewatered in a Buchner funnel with fitter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 10D is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% consistency in a 50 miUimolar buffer solution of sodium acetate and acetic acid of pH 4.7. The buffer solution, preheated to 120*?, is first mixed with 22,5 mL of a 2% Celluelast® solution (1.5% volume/wt addition of CeUuclast® 1.5 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin', Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120"F via a microwave oven and is then added to the enzyme/buffer mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed tcf "reifct for approximately 1 hour. At the end of the hour, the pulp slurry is quantitatively transferred and dewatered in a Buchner runnel with filter paper. The modified pulp cake is then added /to approximately 1,000 tnL of a 100 ppm NaOCl (4 mL of Clorox® in 2,000 mL of distilled water) solution, mixed, and allowed to react for a minimum of S minutes at room temperature 10 quench any further enzyme reactions with the celJutose. After quenching, the modified pulp slurry is quantitatively transferred and rinsed with approximately 1,500 mL of distilled water and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Preparation of n-Dodecenylsuccinate Disodium Salt: 500 g of distilled water were mixed with 3500 g of n»Dodecenylsuccinic Anhydride (98% concentration, Milliken Chemical Company, Inman, SC) at 70 degrees Centigrade for approximately 16 hours. Following the 16 hour reaction period, 3070 g of a 1 % sodium sulfate solution was added and mixed for one more hour and removed from heat. 1000 g of a 50% sodium hydroxide solution was then slowly added to the emulsion with constant mixing to form a 49% concentration of the n-Dodccenylsuccinic acid monosodium salt. From this, a representative sample was obtained and diluted to 6% concentration with distilled water and the pH was adjusted to 9 with sodium hydroxide solution to form the n-Dodecenylsuccinate Disodium Salt. Preparation of n-Octadecenylsuccinate Disodium Salt: 500 g of n-Octadecenylsuceinic Anhydride (100% concentration, Milliken Chemical Company, Inman, SC) was melted at 70 degrees Centigrade and then mixed with 50 g of distilled water for approximately 16 hours. Following the 16 hour reaction period, the emulsion was removed from heat and 218 g of a 50% sodium hydroxide solution was mixed in along with 2000 g of distilled water to form the n-Qctadecenylsuccinate Disodium Salt. The emulsion was then mixed at room temperature for another 20 hours and then mixed with lOOg sodium sulfate crystals and 400 g distilled water. From this, a representative sample was obtained and diluted to 6% concentration with distilled water. Sample 10E is made from NSK pulp that is modified by the following process: Hie fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120*F is first mixed with 15 mL of a 2% Carezyme® solution (1% voiume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin1, Rochester, NY) in a 1208F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, the pH of the enzyme/pulp sluny is adjusted to approximately 10 with 0.1 normal sodium hydroxide, After pH adjustment, 25 mL of a 6% (wt/vol) solution of n-Dodecenyisuccinate Disodium Salt (preparation described above) is added to the enzyme/pulp sluny to achieve a 5% add¬on level (wt active ehemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at 120°F, After 30 minutes mixing, the pH of the enzyme/pulp/ n-Dodecenylsuccinate slurry is adjusted to pH 7 with 1 normal sulfuric acid. After pH adjustment, 1.75g of calcium chloride (J.T. Baker, Phillipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pulp/ n-Dodecenylsuccinate slurry and mixed for another 5 minutes at 120°F. At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Bucbner runnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 10F is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 1206F is first mixed with 15 mL of a 2% Carezyme® solution {1 % volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnln1® lab mixer (Lightnin1, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120BF via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed 10 react for approximately I hour. At the end of the enzyme reaction period, the pH of the enzyme/pulp slurry is adjusted to approximately 10 with 0.1 normal sodium hydroxide. After pH adjustment, 5 mL of a 6% (wt/vol) solution of n-Dodecenylsuccinate Disodium Salt (preparation described above) is added to the enzyme/pulp slurry to achieve a 1% add¬on level (wt active ehemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at 120°F. After 30 minutes mixing, the pH of the enzyme/pulp/ n-Dodecenylsuccinate slurry is adjusted to pH 7 with 1 normal sulfuric acid. After pH adjustment, 0.43g of zinc chloride (J.T. Baker, Phillipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pulp/ n-Dodecenylsuccinate slurry and-mixed for another 5 minutes at 120T. At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample !OG is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to I20aF is first mixed with 15 ml of a 2% Carezyme® solution (1% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lightnin', Rochester, NY) in a 120°F water bath- The unmodified pulp cake is preheated to approximately )20*F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, the pH of (he enzyme/pulp slurry is adjusted to approximately 10 with 0,1 normal sodium hydroxide. After pH adjustment, 25 mL of a 6% (wt/vol) solution of n-Dodecenylsoccinate Disodium Salt (preparation described above) is added to the enzyme/pulp slurry to achieve a S% add¬on level (wt active chemica!/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at 120*F. After 30 minutes mixing, the pH of the enzyme/pulp/ n-DodecenyUuccinate slurry is adjusted to pH 7 with 1 normal sulfuric acid. After pH adjustment, 2,15g of zinc chloride (J.T, Baker, Phillipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pulp/ n-Dodecertylsuccinate slurry and mixed for another 5 minutes at 120°F. At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 10H is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120°F is first mixed with 15 mL of a 2H Carezyme® solution (1% volume/wt addition of Cajezyme® 5.0 L on bone dry pulp) for approximately IS seconds via a Lightoin'® lab mixer (Lightnin1, Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately I20°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to-react for approximately 1 hour. At the end of the enzyme reaction period, the pH of the enzyme/pulp slurry is adjusted to approximately 10 with O.I normal sodium hydroxide. After pH adjustment, 5 mL of a 6% (wt/vo!) solution of n-Ocudecenylsuccinate Disodium Salt (preparation described above) is added to the enzyme/pulp slurry to achieve a 1% add¬on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at 120BF, After 30 minutes mixing, the pH of the enzyme/pulp/n-Octadecenylsuccinaie slurry is adjusted to pH 7 with 1 normal sulruric acid. After pH adjustment, Q,27g of calcium chloride (IT, Baker, Phillipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pu(p/n-0ctadecenylsuccinate slurry and mixed for another 5 minutes at 120°F. At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 101 is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120°F is first mixed with 15 mL of a 2% Carezyme® solution (1% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnin'® lab mixer (Lightnin1, Rochester, NY) in & I20°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightain'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, the pH of the enzyme/pulp slurry is adjusted to approximately 10 with O.I normal sodium hydroxide. After pH adjustment, 25 mL of a 6% (wt/vol) solution of n-Qctadecenylsuccinate Disodium Salt (preparation described above) is added to the enzyme/pulp siurry to achieve a 5% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at 120°F. After 30 minutes mixing, the pH of the en?yme/pulp/ n. Octadecenylsuccinate slurry is adjusted to pH 7 with 1 normal sulfuric acid. After pH adjustment, 1.36g of calcium chloride (J.T, Baker, Phlilipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pulp/ n»Octadeceny!succinate slurry and mixed for another 5 minutes at 120°F, At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desifltigrator before handsheet making. Sample 10J is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency, Distilled water preheated to 120'F is first mixed with 15 mL of a 2% Carezyme® solution (1% volume/wt addition of Carezyme® 5.0 L on bone dry^pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lightnin1, Rochester, NY) in a. 120°F water bath. The unmodified pulp cake is preheated to approximately I20°F via a microwave oven and is then added to the enzyme/water mixture. The mixing fate of the Lightnin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, the pH of the enzyme/pulp slurry is adjusted to approximately 10 with 0.1 normal sodium hydroxide. After pH adjustment, 5 ml of a 6% (wt/vgl) solution of n-Dodecenylsuccimte Disodium Salt (preparation described above) is added to the enzyme/pulp slurry to achieve a 1% add¬on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at I20°F. After 30 minutes mixing, the pH of the enzyme/pulp/ n-Dodecenylsuccinste slurry is adjusted to pH 7 with 1 normal sulfuric acid. After pH adjustment, 0.35g of calcium chloride (J.T, Baker, Phillipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pulp/ n-Dodecenylsuccinate slurry and mixed for another 5 minutes at 120°F, At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPP1 Standard Desintigrator before handsheet making. Sample 10K is made from NSK pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120*F is first mixed with 15 mLof a2*/» Carezyme® solution (1% voiume/wt addition of Carezyme® S.O L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lighuiin', Rochester, NY) in a 120°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, the pH of the enzyme/pulp sluny is adjusted to approximately 10 with O.I normal sodium hydroxide, After pH adjustment, 5 mL of a 6% (wt/vol) solution of n-Qctadecenylsuccinate Disodium Salt (preparation described above) is added to the enzyme/pulp slurry to achieve a T% add¬on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at 120°F, After 30 minutes mixing, the pH of the enzyme/pulp/ n-Octadecenylsuccinau slurry is adjusted to pH 7 with 1 normal sulfuric acid. After pH adjustment, 0.33g of 2jne chloride (J,T. Baker, Phillipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pulp/ n-Octadecenylsuccinate slurry and mixed for another 5 minutes at I20'F. At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desinttgraior before handsheet making. Sample 1OL is made from NSK. pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120*F is first mixed with 15 mL of a 2% Carezyme® solution (1% vo!ume/wt addition of Carezyme® 5,0 L on bone dry pulp) for approximately IS seconds via a Lightain1® lab mixer (Lightnin', Rochester, NY) in a 120°F water bath. The unmodified pulp cake U preheated to approximately 120*F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin'® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, the pH of the enzyme/pulp slurry is adjusted to approximately 10 with 0.1 normal sodium hydroxide. After pH adjustment, 25 mL of a 6% (wt/vol) solution of n-Octadecenylsuccinate Disodium Salt (preparation described above) is added to the enzyme/pulp sluny to achieve a 5% add-on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at 120°F. After 30 minutes mixing, the pH of the enzyme/pulp/ n-OcUdecenylsuccinate slurry is adjusted to pH 7 with 1 normal sulfuric acid. After pH adjustment, 1.66g of zinc chloride (J.T, Baker, Phillipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pulp/ n-Octadecenylsuccinate slurry and mixed for another 5 minutes at 120°F. At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample 10M is made from NSK pulp that is modified by the following process: The fibers are treated at approximately OVo starting consistency. Distilled water preheated to ]20°F is first mixed with 15 mL of a 2% Carezyme® solution (1% volumc/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightnin1® lab mixer (Lightnin1, Rochester, NY) in a S20°F water bath. The unmodified pulp cake is preheated to approximately 120°F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin1® mixer is increased to achieve continuous „turn over and agitation of the pufp sluny and allowed to react forapproximately 1 hour. At the end of the enzyme reaction period, the pH of the enzyme/pulp slurry is adjusted to approximately 10 with 0.1 normal sodium hydroxide. After pH adjustment, 25 mL of a 6% (wt/val) solution of n-Dodecenylsuccinate Disodium Salt (preparation described above) is added to the enzyme/pulp slurry to achieve a 5% add¬on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at 120°F. After 30 minutes mixing, the pH of the enzyme/pulp/ n-Dodecenylsuccinate slurry is adjusted to pH 7 with 1 normal sulruric acid. After pH adjustment, 2.35g of zinc chloride (J.T. Baker, Phillipsburg, NJ) dissolved in 20 mL distilled water is added to the enzyme/pulp/ n-Dodecenylsuccinate slurry and mixed for another 5 minutes at 120T. At the end of the treatment, the pulp sluny is quantitatively transferred and dewatered in a Buchner funnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standard Desintigrator before handsheet making. Sample ION is made from NSK. pulp that is modified by the following process: The fibers are treated at approximately 3% starting consistency. Distilled water preheated to 120BF is first mixed with 15 mL of a 2% Carezyme® solution (1% volume/wt addition of Carezyme® 5.0 L on bone dry pulp) for approximately 15 seconds via a Lightniri® lab mixer (Lightnin1, Rochester, NY) in a 1206F water bath. The unmodified pulp cake is preheated to approximately t20*F via a microwave oven and is then added to the enzyme/water mixture. The mixing rate of the Lightnin1® mixer is increased to achieve continuous turn over and agitation of the pulp slurry and allowed to react for approximately 1 hour. At the end of the enzyme reaction period, the pll of the enzyme/pulp slurry is adjusted to approximately 10 with 0,1 normal sodium hydroxide. After pH adjustment, 25 mL of a 6% (wt/vol) solution of n-Dodecenylsuccioate Disodium Salt (preparation described above) Js added to the enzyme/pulp slurry to achieve a 5°/a add¬on level (wt active chemical/wt dry fiber basis) and allowed to continue mixing for 30 more minutes at I20°F. After 30 minutes mixing, the pH of the enzyme/pulp/ n-Dodecenylsucctnate slurry is adjusted to pH 7 with 1 normal sulfuric acid. After pH adjustment, l,75g of calcium chloride (J.T, Baker, Phillipsburg, NJ) dissolved-irrUO mL distilled water is added to the enzyme/pulp/ n-Dodecenylsuccinate sluny and mixed for another 5 minutes at 120°F. At the end of the treatment, the pulp slurry is quantitatively transferred and dewatered in a Buchner runnel with filter paper. The resulting modified pulp cake is then diluted to 2,000 mL with tap water and disintegrated for 3,000 revolutions in a TAPPI Standaid-Desintigmtor^erbre handsheet making. Table 10 gives the results of the dry zero span tensile index, bending modulus/dry tensile ratio, dry tensile and tensile index, caliper, and basis weights of the low density handsheet samples made. It can be seen from the Table that enzyme modification of the fibers with Carezyme® followed by the debonder and salt addition results in substantial reduction of the dry zero span tensile index (DZST) of the NSK fibers while maintaining or improving the overall dry tensile index (DT) of the sheet compared to the handsheet samples produced from unmodified control fibers. In addition, the sheets produced from the modified fibers exhibit substantially reduced bending modulus/dry tensile ratios versus the control sample. The bending modulus/dry tensile ratio average for the handshects produced from Carezyme® and debonder and enzyme only modified fibers are 564 cm"1 and 673 cm':, respectively, which corresponds 10 an average reduction of 30.5% and 17.1%, These reductions indicate improved flexibility and softness at equal caliper and dry tensile strength with the preferred being the combination of Carezyme® and debonder, Table 1Q (Table Removed) Cz e Carezyme® 5.0 L DDS " n-Dodecenylsuccinate Disodium Salt ODS = n-0ctadecenylsuccin«« Disodium Salt ZnClj -s Zinc Chloride CaCU= Calcium Chloride * * ; Not an example of the present invention, We claim: 1. A method for preparing modified cellulosic fibers, comprising combining one or more cellulase enzymes, cellulosic fibers, and one or more debonding agents, wherein the cellulosic fibers are allowed to react with the one or more cellulase enzymes and the one or more debonding agents for a period sufficient to reduce the dry zero span tensile index of the fibers by 35% to 65% compared with the dry zero span tensile index of the corresponding unmodified cellulosic fibers and to reduce the wet zero span tensile index by at least about 70% compared with the wet zero span tensile index of the corresponding unmodified cellulosic fibers, wherein the fibers are at least partially bleached. 2. The method as claimed in claim 1, wherein the one or more enzymes, the cellulosic fibers and the one or more debonding agents are allowed to react for a period sufficient to reduce the dry zero span tensile index of the fibers by 40% compared with the dry zero span tensile index of the corresponding unmodified fibers. 3. The method as claimed in claim 3, wherein the one or more enzymes, the cellulosic fibers and the one or more debonding agents are allowed to react for a period sufficient to reduce the dry zero span tensile index of the fibers by 45% compared with the dry zero span tensile index of the corresponding unmodified fibers. 4. The method as claimed in claim 1, wherein the one or more debonding agents is mixed with the cellulosic fibers after the fibers are reacted with the one or more enzymes. 5. The method as claimed in claim 1, wherein the one or more debonding agents is combined with the fibers at a level of at least about 0.1%, based on the dry weight of the modified fibers. 6. The method as claimed in claim 1, wherein the one or more debonding agents is combined with the fibers at a level of at least about 1%, based on the dry weight of the modified fibers. 7. The method as claimed in claim 1, wherein the one or more debonding agents is selected from the group consisting of saturated and unsaturated fatty acids and fatty acid salts; alkenyl succinic anhydrides; alkenyl succinic acids; alkenyl succinate salts; sorbitan mono-, di- and tri-esters; tertiary amines and derivatives thereof; amine oxides; quaternary amines; silicone-based compounds; particulate clays; particulate silicates; and mixtures thereof. 8. The method as claimed in claim 1, wherein the one or more enzymes includes the endoglucanase. 9. A method for preparing modified cellulosic fibers, substantially as hereinbefore described in any of the Examples. |
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| Patent Number | 221628 | ||||||||||||
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| Indian Patent Application Number | 1621/DEL/1998 | ||||||||||||
| PG Journal Number | 31/2008 | ||||||||||||
| Publication Date | 01-Aug-2008 | ||||||||||||
| Grant Date | 30-Jun-2008 | ||||||||||||
| Date of Filing | 11-Jun-1998 | ||||||||||||
| Name of Patentee | NORTH CAROLINA STATE UNIVERSITY | ||||||||||||
| Applicant Address | 1 HOLLADAY HALL, RALEIGH, NORTH CAROLINA 27695-7003, U.S.A | ||||||||||||
Inventors:
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| PCT International Classification Number | D21C 9/00 | ||||||||||||
| PCT International Application Number | N/A | ||||||||||||
| PCT International Filing date | |||||||||||||
PCT Conventions:
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