Title of Invention

"POLYPROPYLENE FIBRE FOR REINFORCEMENT OF FIBRE CEMENT PRODUCTS"

Abstract

The invention relates to polypropylene fibres for the reinforcement of fibre-cement products, as well as the process for treating these fibres.The fibres according to the invention comprise, on the surface, a coating of organic polymers comprising olefin monomers and comprising polar groups, this coating being obtained by surface treatment with the aid of an aqueous dispersion of the said polymers.The fibre-cement products according to the invention have improved work-of-rupture properties and a better crackling resistance.

Full Text

The present invention relates to a polyopropylcne fibre for reinforcement of fibre cement products, a process for treating this fibre, as well as the fibre-cement products reinforced by this fibre. Solid products made of fibre cement are produced in the most diverse of shapes, such as, inter alia, roofing and cladding elements such as slates, plane or corrugated sheets, pipes and storage tanks. These shaped solid products are manufactured starting from an aqueous hydraulic-setting suspension composed of hydraulic binders, reinforcing fibres and, optionally, fillers. This aqueous suspension is mixed so as to obtain a substantially uniform distribution of the components. The suspension is then dewatered. The fresh product thus obtained may then be shaped, for example in the form of a plane sheet or corrugated sheet or in the form of a tube. Thereafter, the shaped fresh product is left to harden under atmospheric conditions or else under specific pressure, temperature and humidity conditions. The manufacturing process most widely used is the Hatchek process, the technology of which, is applied originally to asbestos cement, is exhaustively described in the work "Asbestzement" [Asbestos Cement] by Harald Klos (Springer Verlag, 1967). Other manufacturing processes are, for example, the Magnani, Mazza, Flow-on, extrusion and injection processes. The Hatschek process is based on the use of dewatering machines with a cylindrical screen. In this process, a mat coming from a dilute asbestos-and-cement suspension contained in a tank is transferred to a felt, via a cylindrical dewatering machine, and is then rolled up to the required thickness using forming rolls. For the manufacture of corrugated sheets, the asbestos-cement sheet formed on the forming roll is cut and removed from this roll after the desired thickness has been reached. Next, this sheet is shaped and hardened between oiled corrugated metal plates. For some applications, it proves useful to compress the fresh product after it has been shaped but before it has hardened (postcompxession). A distinction is thus made between non-compressed fibre-cement shaped products and compressed fibre-cement shaped products. Compressed fibre-cement shaped products have been compressed, between their shaping and their hardening operations, under a pressure equal to or greater than 4.9 MPa (50 kgf/cm2) . These compressed fibre-erement shaped products have normally been subjected, in the fresh state, to pressures of between 9.8 MPa and 24.5 MPa (between 100 and 250 kgf/cm2). Asbestos has both reinforcing properties, due ~o its own tensile strength, and processing qualities in relation to excellent dispersability in an aqueous cement suspension. During the dewatering stage, because of good filtering properties and good affinity with cement, the asbestos fibres can retain the fine suspended particles of the composite mixture during shaping. In the hydrated final product, the high "ensile strength combined with the high elastic modulus and low elongation at break contribute to giving the products manufactured from asbestos cement their known high flexural strength. However, asbestos has become an undesirable component for environmental and health reasons and considerable effort has been dedicated to trying to replace it. Consequently, it is desirable to use new fibres as reinforcing agents and also as processing auxiliaries to be used with the hydraulic binders, for example for reinforcing the cement. No natural or synthetic fibre having all the properties of asbestos fibres has been discovered. The alkali resistance in saturated calcium hydroxide solutions is a particular criterion which reinforcing fibres must meet. It is also important for the fibres to be able to be easily dispersed in a dilute aqueous cement suspension and also for them to remain uniformly dispersed during the addition of other additives when these fibres have to be processed using dewatering techniques in order to give fibre-cement products. Good dispersion of the fibres is important not cr.ly so that they do not form agglomerates and the fibre concentration is homogeneous in the finished fibre- cement product, but also so that the fibres do not orient in a common direction. — This is because, should the fibres adopt a preferred orientation, the fibre-cement product would then have a different strength depending on the direction of the breaking force. The literature already contains numerous publications with regard to the use of various natural or synthetic, organic and inorganic fibres. Fibres made of cellulose, polyamide, polyester, polyacrylonitrile, polypropylene and polyvinyl alcohol, inter alia, have already formed the subject of investigations in the case of cement reinforcement. Likewise, studies on fibres made of glass, steel, aramid and carbon are also known. Among all these fibres, none hitherto has all the required properties, especially for cement. For example, glass has a low chemical stability, steel exhibits corrosion and has too high a density, carbon is too brittle, adheres poorly and is costly, cellulose has insufficient durability and ordinary polyethylene and polypropylene have insufficient tensile strength.. Among_ reinforcing fibres currently used, polyacrylonitrile (PAN) and polyvinyl alcohol (PVA) fibres are generally preferred. By themselves or in combination, these fibres make it possible to produce a shaped fibre-cement product having a high tensile strength in combination with acceptable ductility. Unfortunately, PAN and PVA fibres are expensive and considerably increase the manufacturing cost of -he fibre-cement products containing them. Polypropylene fibres have excellent alkali resistance, even at temperatures which may be as high as 110°C. They are durable and inexpensive fibres. However, it is generally accepted that polypropylene fibres are technically insufficient when it is a question of reinforcing materials whose cement-based matrix is relatively brittle. It has already been sought to improve ~he properties of polypropylene fibres, especially by incorporating additives into the fibre mass. Document JP 6-219797 from Daiwabo Create describes two-component polypropylene fibres containing calcium carbonate in their peripheral part. In GB-2,030,891, different particles are forced into thermoplastic fibres by bombardment. Documents GB-2,021,552, WO 94/20654, EP-A-0,240,167 and WO 87/04144 describe hydraulic-setting products whose reinforcing fibres are produced initially from modified polymer. The fibres each time are therefore modified throughout the mass, resulting in many disadvantages. This incorporation of additives into the very mass of the polypropylene fibres increases the manufacturing costs and results in modification of the mechanical properties of the reinforcing fibre, especially by decreasing its tenacity. Document EP 0,310,100 also describes polyolefin fibres containing inorganic particles forced into the mass of the fibre, none of the particles being exposed on the surface of the fibre. These fibres are manufactured from a film which may have undergone certain surface treatments. The surface treatments mentioned consist of chemical, electrical or mechanical modifications of the fibre. This document also mentions applying surfactants to the surface of the fibre. Stereoregular polypropylene fibres are also known which have a high tensile strength (EP-0,525,737 frcrr. Daiwabo). Patent EP-A-0,537,129 describes solid shaped manufactured cement products reinforced by this type of polypropylene fibre. A problem still encountered in fibre-cement sheer products reinforced by this type of fibre is the appearance of cracks in the- edges of the sheet, in particular during long-term ageing of these products. Moreover, the work of fracture is of considerable importance for the use of fibre-cement products. A high value (highly ductile product) is desirable. A high ductility is furthermore important so as to be able, when required, to machine fibre-cement components: drilling, nailing, sawing, etc. Finally, safety during the use of products, such as roofing, is also increased thereby, since too rapid or too violent a fracture under load is thus avoided. In uncompressed fibre-cement products reinforced by polypropylene fibres, the work of fracture generally has a very low value. In light of the abovementioned reasons, in particular because of their low cracking resistance and their low work of fracture, the use of compressed and uncompressed fibre-cement products, whose reinforcing fibres are polypropylene fibres, has hitherto remained very limited. It may be noted that certain polypropylene fibres are used, in small quantity, in concrete products in order to reduce cracking of the concrete. For example, a fibre sold under the name Crackstop® is known. This type of fibre has insufficient mechanical properties and is therefore completely unsuitable for reinforcing fibre-cement products, such as roofing or cladding elements. This is because fibre-cement products are characterized by a very high surface/thickness ratio. The problem of cracking in such products is therefore completely different to that in solid concrete products. In fibre-cement products, the fibres must actually fulfil a reinforcing function, while in concrete products the quantity of fibres is markedly less and does not actually fulfil this reinforcing function. In addition, the proportions of the various constituents, especially cement, are very different in fibre-cement products and concrete products. Likewise, the processing conditions and the service conditions are completely different. It has now been discovered, unexpectedly and surprisingly, that polypropylene fibres, even ordinary-polypropylene fibres, but which have undergone a simple surface treatment with the aid of an aqueous poj.ymer dispersion, give good results, tha~ is to say that it is possible to produce a shaped fibre-cement product having a high work jDf fracture and good cracking resistance by means of polypropylene fibres which have undergone this surface treatment. The object-of the invention is to provide shaped fibre-cement products which avoid the drawbacks specific to the known prior art. One of the objects of ~he invention is especially to provide a shaped fibre-cement product having good mechanical properties, such as a high work of fracture and good cracking resistance, at a low manufacturing cost. The subject of the present invention is a polypropylene fibre for the reinforcement of shaped fibre-cement products manufactured by means of a hydraulic-setting composition comprising, especially, water, hydraulic binders and reinforcing fibres. The fibres according to the invention comprise a coating of organic polymer comprising olefin monomers and comprising polar groups, this coating having been applied by surface treatment with the aid of an aqueous dispersion of this polymer. According to one embodiment, the said aqueous dispersion comprises, by itself or as a mixture, an organic polymer chosen from homopolymers and copolymers of olefin monomers modified after synthesis (for example, by grafting) by polar groups. The said polar groups are chosen, for example, from maleic anhydride, acrylic acid and methacrylic acid. The said aqueous dispersion may also comprise, by itself or as a mixture, an organic polymer chosen from homopolymers and copolymers of olefin monomers modified by oxidation. The said dispersion may also comprise, by itself or as a mixture, an organic polymer chosen from copolymers of an olefin monomer and of a polar monomer, such as, for example, methacrylic acid and acrylic acid, optionally neutralized by ions. Advantageously, the polypropylene fibres which have undergone the sai'd "treatment comprise from 0.05 to 5% by weight and preferably from 0.15 to 1.5% by weight, with respect to the weight of fibre, of the said coating of organic polymer comprising polar groups. The polypropylene fibres according to the invention preferably have a denier (d) of between 0.5 and 10 and even more preferably between 0.5 and 2. The fibres may be advantageously chopped to a length which may range from 2 to 20 mm; preferably, the length of the fibres ranges from 5 to 10 mm. The cross-section of the fibres may be circular or of irregular shape, for example in the shape of an X or Y. The fibres may be crimped while they are being drawn or thereafter. The technique of crimping the fibres may include operations such as false twisting, air-jet entanglement treatment (comprising the Taslan treatment) or compression treatment (namely stuffing-box treatment). The fibres according to the invention may also be obtained by fibrillating an extruded polypropylene film. The fibres may then be in tape form. The reinforcing fibres may be obtained from a resin of any type of polypropylene normally used. The polypropylene fibres, or some of the polypropylene fibres, may optionally comprise fillers. furthermore, they may optionally comprise an agent for making the fibres hydrophilic, such as an alkylphosphate alkali metal salt, such as a sodium or potassium salt, advantageously containing from 8 to 18 carbon atoms. _ According to another embodiment, the fibres according to the invention, or some of the fibres according to the invention, may ' consist of highly crystalline polypropylene having, for example, a tensile strength in the fibre state of greater than 490 N/mm% a weight-average molecular weight to number-average molecular weight ratio (Q) According to another . embodiment of the invention, the rei-nforcing fibres, or some of the reinforcing fibres, may be two-component polypropylene fibres consisting, for example, of a core and an outer layer, the outer layer of which contains particles of alkaline-earth metal carbonates such as, for example, calcium carbonate, magnesium carbonate or mixtures thereof. The subject of the present invention is also a process for the surface treatment of .polypropylene fibres for the reinforcement of fibre-cement products; this process consists in bringing polypropylene fibres into contact with an aqueous dispersion of organic polymers comprising olefin monomers and comprising polar groups. Preferably, the concentration of the aqueous dispersion is from 0.5 to 40% of organic polymers. Particularly advantageously, the said surface treatment is carried out by bringing the fibres into contact with an applicator roller immersed in a treatment bath containing the said aqueous dispersion. Any other form of treatment may be envisaged, such as applications by dip coating, by spraying or by curtain coating. Depending on the technique used for the surface treatment, the concentration of the dispersion must be adjusted. For bath treatments, the aqueous dispersion preferably has a concentration of organic polymers of between 0.5 and 10% of dry matter. For spraying- surface treatments, preferred concentrations of the dispersion are, for example, between 10 and 40% of dry matter. The said surface treatment is carried out, as required, before, during or after the step of drawing the fibres. Depending on the case, the treatment is carried out on hot fibres or cooled fibres. _ Several surface treatments may optionally be provided during the manufacture of the reinforcing fibres. Generally, the treatment bath may be set between 20 and 80°C. The subject of the present invention is also shaped fibre-cement products comprising reinforcing fibres as described hereinabove and reinforcing fibres treated by the process described hereinabove. Preferably, the fibre-cement products comprise from. 0.3 to 4% and more preferably from 0.5 to 2.5% by weight, with respect to the initial total dry mixture, of polypropylene fibres according to the invention. The fibre-cement products according to the invention may additionally comprise inorganic fibres or organic fibres other than the polypropylene fibres according to the invention. Examples of organic fibres which can be used in combination with treated polypropylene fibres are polyacrylonitrile, polyvinyl alcohol, polyamide, polyester, aramid, carbon and polyolefin fibres. Examples of inorganic fibres which can be used in combination with treated polypropylene fibres are glass fibres, rock wool, slag wool, wollastonite fibres, ceramic fibres and the like. For reasons of simplicity, reference is made in the present description to cement as the preferred binder. However, any other hydraulic-setting binder may be used instead of cement. Appropriate hydraulic- serving binders should be understood to mean materials which contain an inorganic cement and/or an inorganic adhesive or binder which hardens by hydration. Particularly suitable binders which harden by hydration are especially, for example Portland cement, high-alumina cement, blast-furnace Portland cement, trass cement, slag cement, plaster, calcium silicates formed by autoclave treatment and combinations of particular binders. Fillers and additives of the most diverse type, which, for example, may improve the dew.atering behaviour of the suspensions on the dewatering machines, are frequently added to the binders. Possible additives are materials such as fly ash, amorphous silica, ground quartz, ground rock, clays, blastfurnace slags, carbonates, pozzolana, etc. The total quantity of fillers is preferably less than 50% by weight with respect to the initial total weight in the dry state of the product. The product according to the invention may furthermore comprise processing fibres, preferably in a quantity equal to or less than 10% by weight with respect to the initial total weight in the dry state of the product. The product according to the invention may, for example, be a roofing or cladding element, such as a plane sheet or corrugated sheet, or any other ancillary element of diverse shape. The invention is described below in greater detail by means of particular examples of embodiments. EXAMPLES In the following examples, fibre-cement products reinforced by polypropylene fibres treated according to the invention are compared with fibre-cement products produced with the same polypropylene fibres, but untreated. Treatment baths used Bath 1) : MICHEM® emulsion 94340-E composition from Michelman International & Co., diluted with water-to a solids concentration of 4%. This composition is an aqueous dispersion comprising maleic-anhydride-grafted polypropylene of the Epolene® E-43 type from Eastman Chemical. The dispersion has the following characteristics: - emulsifiers: 'nonionic - average particle size: 40 nm - pH: 7.5 - 9.0. Bath 2): Same composition as Bath 1), diluted to 4%, to which has been added 0.1% of a surfactant of the Silwet® L-77 type from OSI Specialities (a-1,1,1, 3, 5, 5, 5-heptamethyltrisiloxanylpropyl-co-methoxy-poly(ethylene oxide). Bath 3) : Composition No. M 59840 from Michelman International & Co., diluted with water to a solids concentration of 4%, to which has been added 0.1% of a surfactant of the Silwet® L-77 type from OSI Specialities. Composition No. M 59840 is an aqueous dispersion comprising a maleic-anhydride-grafted ethylene-propylene copolymer of the A-C® X 597 type from Allied Signal. Bath 4) : Composition No. M 93935 from Michelman International & Co., diluted with water to a solids concentration of 4%, to which has been added 0.1% of a surfactant of the Silwet® L-77 ~ype from OSI Specialities. Composition M93935 is an aqueous dispersion comprising an oxidized high-density polyethylene (HDPE) of the AC® 392 HDPE type from Allied Signal. The dispersion has the following characteristics: - emulsifiers: nonionic - average particle size: 40 nr. - pH: 9.0 - 10.5. Bath 5) : Aquacer 524 composition from. Byk-Cera, diluted with water to a solids concentration cf 4%. This composition is an aqueous dispersion comprising maleic-anhydride-grafted polypropylene of the Epolene® E-43 type from Eastman Chemical. The dispersion contains anionic emulsifiers. Bath 6) : Aquacer 841 composition froir. Byk-Cera, diluted with water to a solids concentration cf 4%. This composition is an aqueous dispersion comprising maleic-anhydride-grafted polypropylene of the Epolene® E-43 type from Eastman Chemical. The dispersion contains cationic emulsifiers. Bath 7) ; Same composition as Bath 1) but diluted to a solids (grafted polypropylene) concentration of 0.2%. Bath 8) : Same composition as Bath 1) but diluted to a solids (grafted polypropylene) concentration of 1.0%. Bath 9) : Aquaseal® 1127 composition from Paramelt B.V., diluted to a solids concentration of 1%. This composition is an aqueous dispersion of an ethylene-methacrylic acid copolymer. Bath 10) : Same composition as for Bath 9) but diluted to a solids (ethylene-methacrylic acid copolymer) concentration of 4%. Bath 11): Aquaseal® 1088 composition from Paramelt B.V., diluted to a solids concentration of 1%. This composition is an aqueous dispersion of an ethylene-methacrylic acid copolymer neutralized by Na" ions (ionomer). Bath 12): Same composition as for Bath 11), but diluted to a solids (ethylene-methacrylic acid copolymer neutralized by Na+ ions) concentration of 4%. Several blank' tests are also carried out in order to demonstrate the difference between the fibres treated according to the invention and fibres of the prior art which are treated with known surface-active agents. These agents do not enter into the definition of the polymers comprising olefin monomers and comprising polar gro-ups: Blank A: Composition comprising 4% of a wetting agent based on modified siloxane (used to make the polypropylene fibres hydrophilic) from Schill und Seilacher. Blank B: Composition comprising 4% of Lurol PP-5030-30% (a mixture of emulsifiers,. lubricants and antistatic agents) from Goulston Technologies. Blank C: Composition comprising 4% of hexanol (commonly used as a wetting agent). Preparation of the polypropylene fibres Granules of a standard polypropylene resin (melting point: 165°C; melt flow index (MFI) of 25) are heated in an extruder (the temperature at the end of the extruder varying between 240°C and 280°C) and spun in a conventional manner. The fibres are then drawn using conventional equipment. According to a first method of operation, the spinning and drawing of the fibres are carried out in a discontinuous manner. According to another method of preparation, the spinning and drawing are carried out in a continuous manner. The fibres then Have the following characteristics: - linear density: 1.18 dtex - tenacity: 730 N/mm2 - initial modulus: 7460 N/mm2 - elongation at break: 19.0%. After the fibres have been drawn, they" are impregnated in one of the treatment baths described above by contact with an applicator roller immersed in the treatment bath. The quantity of dry matter "-in the treatment bath applied to the fibres by this treatment is approximately 0.15% to 1.5% by weight with respect to the weight of fibre. This concentration is measured by nuclear magnetic resonance (NMR) using a commercial apparatus OXFORD NMR QP 20+. This equipment is used in the standard way to quantify the finish coatings applied to. the surface of the fibres, especially using textile technology. This apparatus is designed to determine the concentration of a defined component, which contains protons in its molecular structure. Comparative tests are also carried out: 1.) without impregnation in the treatment bath; 2.) with impregnation in surfactant compositions (Blank A, Blank B and Blank C). Next, the fibres are chopped in a conventional manner to a length of 8 mm before being used in the mixtures of building materials. In Examples 1 to 6 below, the impregnation with the treatment bath is carried out after the fibres have been drawn, but it is also possible to carry out this treatment during the drawing step or directly after spinning, before the fibres have been drawn. In Example la below, the treatment was carried out between the fibre-spinning step and the fibre-drawing step. EXAMPLES 1 to 6 and la Preparation of the mixtures and processing on a Hatschek machine. The following compounds are mixed in water: - cement: 77.2% - polypropylene fibres surface-treated in one of the baths described above: 1.8% - Kraft cellulose pulp refined to 65°SR (Schopper-Riegler): 3.0% - amorphous silica: 3.0%, and - fly ash: 15%. The concentrations given are the solids concentrations with "respect to the total dry matter. This suspension is diluted with water to a concentration of 30 g per litre and then transferred to the tank of a Hatschek machine. Slightly before introducing the suspension into the tank, 200 ppm of a polyacrylamide-type flocculating agent are added in order to improve the retention of the cement. Using the machine, sheets are produced by 22 revolutions of the forming cylinder. Next, the sheets are pressed between oiled steel moulds in a press with an applied specific pressure of 180 bar (17.7 MPa) to an average thickness of 5.5 mm. The sheets are left harden under a plastic cover for 28 days in a relative humidity of 100% at 20°C. Flexural-strength and cracking-resistance mechanical tests The mechanical tests are carried out in the dry state, in air. First of all, the flexural strength of the specimens is determined on a mechanical tester in a conventional three-point bending test. The apparatus records the stress/strain curve. The work of fracture under maximum load (IMOR) expressed in joules per m2 (J/m2) is the integra-1 of the stress/strain function up to the breaking load. The cracking resistance is also determined by a severe test designed to cause cracking along the edges of fibre-cement products (cracking test). Cracks are obtained by artificially creating a moisture gradient between the edges and the central part of the sheets by differential drying between the outer and inner regions of the product. For this purpose, a series of fibre-cement sheets manufactured on a Hatschek machine, compressed and left to harden in a humid atmosphere for 28 days, as described above, 'are cut up into 30 x 30 cm squares and stacked on top of each other, a spacer being inserted every 10 pieces. The top and bottom of the stack (approximately 40 sheets) are provided with two suitable non-absorbent covering sheets made of a material such as steel or polyester. The stack is placed in a ventilated oven at 60°C for 24 h. Cracks then appear along the edges of the sheets. The sheets are examined one by one and the lengths of cracks visible to the naked eye are measured. The lengths of the cracks on each sheet are added and totalized per 5 sheets. The results are given in Table I below. TABLE I (Table Removed) It may be deduced from Table I above that the compressed fibre-cement products reinforced by polypropylene fibres surface-treated by one of the 6 baths described has a greater work of fracture (an increase of 19 to 75%) than _ that of the fibr-e-cement product using the same, but untreated, polypropylene fibres. This improvement in the work of fracture is also noticeable compared with fibre-cement products whose polypropylene fibres were treated with a surfactant (Blank A, B or C). Likewise, the products according to the invention exhibit, in the cracking test, a significant decrease in the measured total length of cracks (from 39 - 84%, depending on the case), whether with respect to the product containing fibres which have not undergone a treatment or compared with products containing fibres which have undergone a treatment with the aid of one of the Blanks A to C. EXAMPLES 7 to 12 Preparation of the mixtures and processing on a Hatschek machine. The same method of preparation as that described for Examples 1 to 6 is used here, apart from the fact that the products are not compressed. The sheets produced using the Hatschek machine are therefore directly hardened, without an intermediate pressing step. The results are given in Table II below. TABLE II (Table Removed) Just as in the case of compressed fibre-cement products, in the case of uncompressed products it may be deduced from the above Table II that the surface treatment of the ordinary polypropylene fibres with one of Baths 7 to 12 described above gives the end product a significant increase in the work of fracture (an increase of from 202 to 403% compared with the product whose fibres have not undergone a treatment). This improvement in the work of fracture is also noticeable compared with fibre-cement products whose polypropylene fibres have been treated with a surfactant (Blank A, B or C). Likewise, the measured values of the total length of cracks in the case of the uncompressed products according to the invention show a decrease of 19 and 24% compared with the product whose fibres have not undergone a treatment. This improvement in the cracking is also observed compared with products whose fibres have been treated with one of Blanks A to C. The invention therefore makes it possible, with a simple and inexpensive surface treatment of the polypropylene fibres, to increase the work of fracture and to improve the cracking resistance of fibre-cement products reinforced by these fibres. This treatment may be applied to any type of polypropylene fibre. The effects of this treatment are particularly f unexpected. Despite the very short time during which the fibres are in contact with the composition of the treatment bath, there seems to be good adhesion of the particles to the fibre. These effects are all the more unexpected as, despite the mixing of the fibres and the cement in a large quantity of water and with significant stirring, during the manufacture of the fibre-cement products, the effect of the fibre treatment is maintained. It should also be noted that these results are obtained when the fibre-cement products are subjected to tests under the most unfavourable conditions for measuring the work of fracture, that is to say in the dry state in air.

Documents:

2998-del-1998-abstract.pdf

2998-del-1998-claims.pdf

2998-del-1998-correspondence-others.pdf

2998-del-1998-correspondence-po.pdf

2998-del-1998-description (complete).pdf

2998-DEL-1998-Form-1.pdf

2998-DEL-1998-Form-19.pdf

2998-del-1998-form-2.pdf

2998-del-1998-form-3.pdf

2998-DEL-1998-Form-4.pdf

2998-DEL-1998-Form-6.pdf

2998-del-1998-form-62.pdf

2998-del-1998-gpa.pdf

2998-del-1998-pct-210.pdf

2998-del-1998-petition-138.pdf