Title of Invention

A PROCESS FOR PRODUCING SURFACE ENHANCED MOULDED FIBRE PARTS

Abstract

Process for producing surface-enhanced moulded fibre parts said process comprising applying to the prefabricated or prehardened fibre web a laminating material provided with an adhesive which is a thermost resin curable and the resultant laminated article is cured by under pressure by heating to a temperature above the initiation temperature used in the fibre web characterized in that the adhesive used is a thermost resin or resin-hardener mixture which is nontacky at room temperature.

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10] "PROCESS FOR MAKIING IMPROVED SURFACES OR ,MOLDED PARTS MADE OF NONWOVEN FABRICS" BAKELITE AG, of Gennaer Str. 2-4, D-58642 Iserlohn-Letmathe, Germany, The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- In an improved process, a pulverulent thermoplastic mixture of low melt viscosity is spread onto the surface of the laminating material, melted by reheating, and then cooled. This, gives a uniform coating on t-he surface of the lamination material. The disadvantage of this process is that the recovery forces in the laminating material when hot are frequently more powerful than the adhesive strength of the hot-melt adhesive. In the case of parts with complicated shapes in particular, this leads to defects where the laminating.material parts, from the substrate. These separation phenomena are particularly marked in the case of mouldings exposed to frequent temperature changes or intense insolation. The object of the invention is therefore to provide a process intended for the surface enhancement of moulded fibre parts which has similar technical elegance and similar simplicity to the hot-melt coating process mentioned, but in which disadvantageous separation phenomena do not occur. According to the present invention there is provided a process for producing surface enhanced moulded fibre parts said process comprising applying to the prefabricated or prehardened fibre web a laminating material provided with an adhesive which is a thermoset resin curable and the resultant laminated article is cured by under pressure by heating to a temperature above the initiation temperature used in the fibre web characterized in that the adhesive used is a thermoset resin or resin-hardener mixture which is nontacky at room temperature. It has been found that moulded fibre parts can also be given a high-quality enhanced surface if the adhesive used for the lamination process is a thermoset resin or resin-hardener mixture which has not yet been fully cured and is nontacky at room temperature. Laminating, material provided with a dhesive of this type is applied to the prefabricated fibre web or to mouldings made from fibre web, and the resultant laminated article is heated to a temperature above the initiation temperature for the curing reaction of the resin or of the resin-hardener mixture. In an improved process, a pulverulent thermoplastic mixture of low melt viscosity is spread onto the surface of the laminating material, melted by reheating, and then cooled. This, gives a uniform coating on the surface of the lamination material. The disadvantage of this process is that the recovery forces in the laminating material when hot are frequently more powerful than the adhesive strength of the hot-melt adhesive. In the case of parts with complicated shapes in particular, this leads to defects where the laminating, material parts from the substrate. These separation phenomena are particularly marked in the case of mouldings exposed to frequent temperature changes or intense insolation. The object of the invention is therefore to provide a process intended for the surface enhancement of moulded fibre, parts which has similar technical elegance and similar simplicity to the hot-melt coating process mentioned, but in which disadvantageous separation phenomena do not occur. According to the present invention there is provided a process for producing surface enhanced moulded fibre parts said process comprising applying to the prefabricated or prehardened fibre web a laminating material provided with an adhesive which is a thermoset resin curable and the resultant laminated article is cured by heating to a temperature above the initiation temperature used in the fibre web characterized in that the adhesive used is a thermoset resin or resin-hardener mixture which is nontacky at room temperature. It has been found that moulded fibre parts can also be given a high-quality enhanced surface if the adhesive used for the lamination process is a thermoset resin or resin-hardener mixture which has not yet been fully cured and is nontacky at room temperature. Laminating, material provided with adhesive of this type is applied to the prefabricated fibre web or to mouldings made from fibre web, and the resultant laminated article is heated to a temperature above the initiation temperature for" the curing reaction of the resin or of the resin-hardeher mixture. - 3 -During this, the thermoset resins cure in the form of a film which bonds to the fibre-web surface during the curing reaction and gives, over the entire surface, irreversible adhesive bonding of the lamination 5 material so that no separation phenomena result, even on exposure tc> extreme temperature differences or insolation. This is surprising, since the melt viscosity of 1Q thrmosets is generally higher than that of thermoplastics and the curing temperature used is significantly above the melting point of the thermoplastic binders used hitherto, and therefore the recovery forces arising when the pressure is reduced in 15 the press tool are significantly higher than when thermoplastics are used. Thermoset resins are generally brittle. It is therefore also surprising that the lamination materials coated 20 according to the invention with thermoset resins remain stable even when rolled up or shaped, and do not break apart. Another advantage of the novel process is that the 25 moulded fibre parts may be surface enhanced by applying the thermoset resins or resin-hardener mixtures which have not yet fully cured either to prefabricated mouldings made from web material or to the laminating material. This method of processing also allows the 30 thermoset resins used for surface enhancement to crosslink at the interface with the resins used as binders for the textile fibres. This applies particularly if the resins used for binding the fibres and for enhancing the surfaces of the mouldings are 35 identical or react with one another. Another advantage arising from these crosslinking reactions at the interface is an increase in the stability of the mouldings. According to the invention, therefore, thermoset resin or, respectively, resin-hardener mixture and a laminating material are applied to the surface(s) to be 5 enhanced of prefabricated mouldings and the resultant units (laminated articles) are heated to temperatures above the melting point and above the initiation temperature for the curing reaction of "the thermoset resins. Once the thermoset resins have cured, the 10 resultant surface-enhanced parts are further processed in a manner known per se. Another simplification of the overall production process results from applying thermoset resin, resin- 15 hardener mixture and a laminating material to the surface(s) to be enhanced of prefabricated or prehardened fibre webs. The parts produced in this way (laminated articles) are heated, under pressure and with shaping, to temperatures above the melting point 20 and above the initiation temperature of the curing reaction of the resins used in the coating and above the initiation temperature of the resins used as binders in the web. During this there is simultaneous curing of the binders in the web and the resins in the 25 coating and, if the binders in the web and the resins of the coating are identical or can react with one another, these thermosets crosslink with one another at the interface. Once the coating and the binders in the web have cured, 30 the resultant parts are further processed in a manner known per se. Possible versions of the process for surface enhancement with the use of a laminating material are 35 given below: • the thermoset resin or resin-hardener mixture is applied to fibre web which has not yet been heat-treated or prehardened, and is heated to a temperature above the melting point but below the initiation temperature for the curing reaction of the resin. During this the resin is melted and disperses to give a thin layer. The laminating material is 5 applied to this layer, either directly or after interim cooling and reheating, and the resultant product is then heated, if desired with shaping, to a temperature above the initiation temperature for the curing of the resin, and, once the thermoset resin 10 has cured, is cooled and further processed in a manner known per se. • The thermoset resin or resin-hardener mixture is applied to laminating material and heated to a 15 temperature above the melting point but below the initiation temperature for the curing reaction of the resin. During this, the resin is melted and disperses to give a thin layer. The laminating material thus provided with adhesive is applied, either directly or 20 after interim cooling and reheating, to fibre web which has not yet been heat-treated or prehardened, and the resultant product (laminated article) is then heated, if desired with shaping, to a temperature above the initiation temperature for the curing of 25 the resin, and, once the thermoset resin has cured, is cooled and further processed in a manner known per se. • The thermoset resin or resin-hardener mixture is 30 applied to a fully cured and preshaped moulded fibre part and heated to a temperature above the melting point but below the initiation temperature for the curing reaction of the resin. During this, the resin is melted and disperses to give a thin layer. The 35 laminating material is applied to this layer, either directly or after interim cooling and reheating, and the resultant product is then heated to a temperature above the initiation temperature for the curing of the resin, and, once the thermoset resin has cured, .1 is cooled and further processed in a manner known per se. • The thermoset resin or resin-hardener mixture is 5 applied to laminating material and heated to a temperature above the melting point but below the initiation temperature for the curing reaction of the resin. During this, the resin is melted and disperses to give a thin layer. A fully cured and preshaped 10 moulded fibre part is applied to this layer, either directly or after interim cooling and reheating, and the resultant product is then heated to a temperature above the initiation temperature for the curing of the resin, and, once the thermoset resin has cured, 15 is cooled and further processed in a manner known per se. In the first two versions it is advantageous for the thermoset resin used for the coating process to 20 comprise a resin which can be cured using formaldehyde, in particular a hardener-free novolak or hardener-free modified novolak, if the binder in the fibre web is a mixture of a resin curable using formaldehyde and a substance which releases formaldehyde when heated, for 25 example a novolak-hexamethylenetetramine mixture. The formaldehyde released when this binder is cured also suffices for the curing of the thin layer of molten novolak. Another advantage of this version of the process is 30 that there is a significant reduction in formaldehyde emissions during the production process. Preferred methods of carrying out the process are given below: 35 • In a continuous production process and in the form of a continuous web, laminating material provided with an adhesive which is a thermoset resin or resin mixture curable using formaldehyde is applied to the prefabricated or prehardened fibre web comprising a resin curable using formaldehyde and a hardener releasing formaldehyde when heated, and the resultant laminated article is then cured under pressure at a 5 temperature above the initiation temperature for the curing reaction of the binder used in the fibre web and that of the adhesive, and the formaldehyde released in the curing reaction of the binder serves as hardener for the adhesive. This gives a fully 10 cured web material from which sheets of the desired size and shape are stamped out or cut out. • In a continuous production process and in the form of a continuous web, laminating material provided with 15 an adhesive which is a thermoset resin or a resin mixture curable using formaldehyde is applied to prehardened or merely prefabricated fibre web comprising a resin curable using formaldehyde and a hardener releasing formaldehyde when heated, and the 20 resultant laminated article is then annealed at a temperature above the melting point of the adhesive and, providing a fibre web is used which has not yet been prehardened, above the melting point of the resin used as binder, and is then cooled and then 25 stamped out or cut to shape. The laminated article (semifinished product) which has been stamped out or cut to shape is then cured under pressure, with shaping, at a temperature above the initiation temperature for the curing reaction of the binder 30 used in the fibre web and that of the adhesive, and the formaldehyde released in the curing reaction of the binder serves as hardener for the adhesive. • Alternatively, in a batchwise process, cut-to-shape 35 laminating material provided with an adhesive which is a thermoset resin curable using formaldehyde is applied to the prefabricated or, respectively, prehardened and cut-to-shape fibre web comprising resin curable using formaldehyde and a hardener releasing formaldehyde when heated, and the resultant laminated article is then cured at a temperature above the initiation temperature for the curing reaction of the binder used in the fibre web and that 5 of the adhesive, and formaldehyde released in the curing reaction of the binder serves as hardener for the adhesive. The pressure used in these processes is of the same 10 order of magnitude as used hitherto in corresponding processes of the prior art. A preferred method for cut-to-shape laminating mouldings made from fibre web is to apply laminating 15 material provided with an adhesive which is a resin-hardener mixture to cured and shaped mouldings made from fibre web and to heat the resultant laminated article above the initiation temperature for the curing reaction of resin-hardener mixture. 20 An advantage of laminating prefabricated, moulded fibre parts is that less heat treatment is needed to cure the thin layer of thermoset resin than to cure a textile web. This means that products with relatively low heat 25 resistance can be used as laminating material. The fibre used for the novel process may be the same as that used in conventional production of moulded fibre parts. This is essentially reprocessed fibre material 30 from textile recycling and is composed predominantly of cotton fibres or polyester fibres, but generally also comprises other fibres, e.g. wool, jute, flax, sisal, nylon fibres or acrylic fibres. The fibres may comprises additives known per se, e.g. lubricants, spin 35 finishes, fungistats or hydrophobicizers. The fibre material used may also comprise inorganic fibres. The production of the prehardened fibre webs or of the moulded fibre parts also takes place in a manner known 27/12/99 19:08 FAX 06203922283 DrWllhelmBakellt - 9 -per se, as described, for example, in Kunststoff Handbuch [Plastics "Handbook] Vol. 10 "Duroplaste" [Thermosets], pp. 766-768. 5 The laminating materials used may likewise be any sheet material, e.g. high-quality nonwovens, knits or wovens, as used hitherto for laminating moulded fibre parts, as "long as they are sufficiently heat-resistant not to be damaged at the curing temperatures for the thprmoset 10 resins. Suitable resins for the adhesive bonding of the lamination materials are in principle any thermoset resin or resin-hardener mixture which is nontacky at 15 room temperature, or also mixtures comprising these resins and, if desired, hardeners, with modifier resins known per se. Examples of these curable resins are epoxy resins, unsaturated polyesters, urea formaldehyde resins, melamine-formaldehyde resins, melamine-phenol- 20 formaldehyde resins and phenol-aldehyde resins, and also combinations of these resins with one another or with other modifier resins, in particular with from 5 to 50% of flexibilizing resins, e.g polyvinyl butyral, polyvinyl alcohols or phenoxy resins. Preference is 25 given to phenol-formaldehyde resins. The direct coating of the moulded fibre parts or of the uncured or, respectively, the prehardened fibre webs, or of the laminating materials, takes place by 30 processes known per se, using spreading, rolling, trowelling, casting, dipping or spraying methods, using appropriate pastes, aqueous dispersions or solutions in organic solvents. 35 The powder method is the preferred coating process. In this, the thermoset resins or resin-hardener mixtures are applied as finely ground powders to the surfaces to be coated. Particularly suitable materials for this are resins or resin-hardener mixtures whose melt viscosity 27-DEC-1999 22:44 0620392; when subsequently heated is sufficiently low to allow adequate wetting of the substrate. The preferred melt viscosity, measured at 175°C, is less than 1000 mPas. During this short period of heating above the melting 5 point of the thermoset resins, preferably using IR radiant heaters, a thin coherent film of the resin or resin-hardener mixture forms on the textile web or laminating material and rapidly cools, thus becoming solid and nontacky. 10 In the next process step, fibre web and laminating material are combined with one another by one of the process methods described above and bonded to one another using pressure and heat. The resultant moulding is then cooled and further processed in a manner known 15 per se. Example 1 The thermoset resin used for surface enhancement in the 20 example is a phenol novolak which has been modified with 10% phenoxy resin and has a melting point of 70°C and a melt viscosity, measured at 175°C, of 420 mPas. Aerodynamic methods of web formation are used to 25 produce an as yet uncured textile web with 25% content of phenol novolak-hexamethylenetetramine as binder (base web). A web (40 g/m2) of high visual quality (outer web) coated with a thin layer (20 g/m2) of the modified 30 phenol novolak is added to one side of this fibre web and fixed to the base web using heat (75°C) in an oven. The web laminated in this way is then subjected to a shaping and curing process in a hot tool at from 180 to 220°C. During this, the formaldehyde released from the 35 hexamethylenetetramine present as a hardening agent in the base web suffices for full concomitant curing of the thin phenol novolak layer present on the inner side of the laminated-on outer web. This gives a moulded textile part with a thermoset adhesive-bonded layer 27/12/99 19:08 FAX which enhances its surface. Another advantage of thio method of carrying cut. the process is A marked reduction in the resultant emission of formaldehyde from the base web. 5 Example 2 The thermoset resin used for surface enhancement in Example ? is a phenol nnvnlnk which haS BEEN modified 10 with 10% by weight of phenoxy resin and has a melting point of 70°C and 6% by weight of hexamethylenetetramine. A thin layer of this finely ground resin-hardener mixture is spread onto one side of a cured and shaped 15 moulded textile part and heated above the melting point. Once the moulded textile part has been coated, a needled web of high visual quality is applied tc it. As a result of rapid cooling, the high-quality web is fixed on the moulded textile part by means of a 20 remeltable, high-flexibility thin film. In a second process step, heat and pressure are used to cure the thin coating above the initiation temperature for the curing reaction of the resin (90s at 130°C). 25 This method of carrying out the process permits the laminating material used for surface enhancement to have a heat resistance lower than that in Example 1. Another advantage of this version of the process is that the thermoset binder in the web and the thermoset 30 resin used for surface enhancement can have different chemical structures and different chemical crosslinking reactions. Example 3 35 The thermoset resin used for surface enhancement in Example 3 is a phenol novolok. which has been modified with 10% by weight of phenoxy resin and has a melting -86223322393 point of 70°C and 6% by weight of hexamethylenetetramine. A thin layer of this finely ground resin-hardener mixture is spread onto one side of a needled web of 5 high visual quality and heated above the melting point of the resin A prefabricated, cured moulded textile part is applied to this coated web. As a result of rapid cooling, the high-quality web is fixed to the moulded textile part by means of a remeltabie, high- 0 flexibility thin film. In a second process step, heat and pressure are used to cure the thin coating at above the initiation temperature for the curing reaction of the resin (90s at 150°C). WE CLAIM: 1. Process for producing surface-enhanced moulded fibre parts said process comprising applying to the prefabricated or prehardened fibre web a laminating material provided with an adhesive which is a thermoset resin curable and the resultant laminated article is cured by under pressure by heating to a temperature above the initiation temperature used in the fibre web characterized in that the adhesive used is a thermoset resin or resin-hardener mixture which is nontacky at room temperature. 2. Process as claimed in claim 1, wherein the said process is a continuous process and the resultant laminated article is prior to curing to a temperature above the intiation temperatures is annealed at a temperature above the melting point of the adhesive and then cooled and then stamped out or cut to shape, and the laminated article which has been stamped out or cut to shape is then cured under pressure. 3. Process as claimed in claim 1, wherein the process is a batchwise process. 4. Process as claimed in claim 1, wherein the laminating material provided with an adhesive which is a resin-hardener mixture is applied to cured and shaped mouldings made from fibre web and the resultant laminated article is then heated above the initiation temperature for the curing reaction of the resin-hardener mixture. 5. Process as claimed in claim 1 to 4, wherein the resin used as adhesive is a hexamethylenetetramine-free novolac. 6. Process as claimed in claims 1 to 5, wherein the resin used as adhesive is a modified phenolic resin. 7. Process as claimed in claim 6, wherein the resin used as adhesive is a phenoxy-resin-modified phenolic resin. 8. Process as claimed in claims 1 to 7, wherein the resin or resin-hardener mixture is applied as a powder to the laminating material. 9. Process as claimed in claim 3, wherein the melt viscosity of the resin or resin-hardener mixture, measured at 175°, is less than 1000 mPas. 10. Process for producing surface-enhanced moulded fibre parts substantially as hereinbefore described with reference to the foregoing examples. Dated this 3rd day of January, 2000. (RITUSHKA NEGI) OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS ■^"

Documents:

10-MUM-2000-ABSTRACT(3-1-2000).pdf

10-MUM-2000-ABSTRACT(GRANTED)-(9-1-2006).pdf

10-mum-2000-cancelled page(27-10-2004).pdf

10-MUM-2000-CANCELLED PAGES(9-11-2004).pdf

10-mum-2000-claim(granted)-(27-10-2004).doc

10-mum-2000-claim(granted)-(27-10-2004).pdf

10-MUM-2000-CLAIMS(3-1-2000).pdf

10-MUM-2000-CLAIMS(GRANTED)-(9-1-2006).pdf

10-mum-2000-correspondence(17-11-2004).pdf

10-MUM-2000-CORRESPONDENCE(20-1-2010).pdf

10-MUM-2000-CORRESPONDENCE(26-10-2009).pdf

10-MUM-2000-CORRESPONDENCE(IPO)-(14-1-2010).pdf

10-MUM-2000-CORRESPONDENCE(IPO)-(19-4-2006).pdf

10-mum-2000-correspondence(ipo)-(8-5-2003).pdf

10-MUM-2000-DESCRIPTION(COMPLETE)-(3-1-2000).pdf

10-MUM-2000-DESCRIPTION(GRANTED)-(9-1-2006).pdf

10-mum-2000-form 1(3-1-2000).pdf

10-MUM-2000-FORM 2(COMPLETE)-(3-1-2000).pdf

10-mum-2000-form 2(granted)-(27-10-2004).doc

10-mum-2000-form 2(granted)-(27-10-2004).pdf

10-MUM-2000-FORM 2(GRANTED)-(9-1-2006).pdf

10-MUM-2000-FORM 2(TITLE PAGE)-(3-1-2000).pdf

10-MUM-2000-FORM 2(TITLE PAGE)-(GRANTED)-(9-1-2006).pdf

10-mum-2000-form 3(27-4-2000).pdf

10-mum-2000-form 3(3-1-2000).pdf

10-mum-2000-form 3(8-11-2004).pdf

10-mum-2000-form 4(5-8-2004).pdf

10-mum-2000-form 5(3-1-2000).pdf

10-mum-2000-petition under rule 137(27-10-2004).pdf

10-mum-2000-petition under rule 137(9-11-2004).pdf

10-mum-2000-petition under rule 138(27-10-2004).pdf

10-mum-2000-petition under rule 138(9-11-2004).pdf

10-mum-2000-power of authority(10-3-2000).pdf

10-MUM-2000-POWER OF AUTHORITY(26-10-2009).pdf

10-MUM-2000-SPECIFICATION(AMENDED)-(27-10-2004).pdf

10-MUM-2000-SPECIFICATION(AMENDED)-(8-11-2004).pdf

10-MUM-2000-SPECIFICATION(AMENDED)-(9-11-2004).pdf