METHOD OF MAKING A SHAPED COMPONENT

Abstract: A method of making a shaped component from a substantially dry resinated feedstock comprising a material selected from the group consisting of particles or fibres of a lignocellulosic material, particles of an exfoliated vermiculite and particles of an expanded perlite, which material has been resinated with a thermosetting resin, or a precursor thereof, the resin being in a latent conditions, i.e. the resin not being polymerised or set, and optionally a hydraulic binder, includes the steps of: (i) placing the substantially dry resinated feedstock on a flexible carrier sheet; (ii) placing the product of step (i) between the platens of a press and subjecting the product of step (i) to suitable conditions of temperature and pressure to mould the product of step (i) into a desired shape and to cause the resin to polymerise or to set; (iii) removing the product of step (ii) from the press; and (iv) optionally removing the flexible carrier sheet from the product of step (iii) to give the shaped component.

Description: METHOD OF MAKING A SHAPED COMPONENT BACKGROUND OF THE INVENTION This invention relates to a method of making a shaped component from a substantially dry, resinated feedstock comprising a material selected from particles or fibres of a lignocellulosic material, particles of an exfoliated vermiculite and particles of an expanded perlite, which material has been resinated. Shaped components made from synthetic organic fibres in combination with lignocellulosic particles or fibres, formed as a non- woven or needle-punched blanket and subsequently pressed to form the required shape, are well known in the automotive components field. In addition, shaped components made from wood fibreboard softboard composites pressed between male and female shaped platens in a press under conditions of temperature and pressure, are also well known in the production of door skins. SUMMARY O TH INVENTION According to a first aspect of the invention, there is provided a method of making a shaped component from a substantially dry resinated feedstock comprising a material selected from the group consisting of particles or fibres of a lignocellulosic material, particles of an exfoliated vermiculite and particles of an expanded perlite, which material has been resinated with a thermosetting resin, which is optionally combined with a thermoplastic resin, or a precursor of either resin, the resin being in a latent conditions, i.e. the resin not being polymerised or set, and optionally a hydraulic binder, includes the steps of: (i) placing the substantially dry resinated feedstock on a flexible carrier sheet; (ii) placing the product of step (i) between the platens of a press and subjecting the product of step (i) to suitable conditions of temperature and pressure to mould the product of step (i) into a desired shape and to cause the resin to polymerise or to set; (iii) removing the product of step (ii) from the press; and (iv) optionally removing the flexible carrier sheet from the product of step (iii) to give the shaped component. In one embodiment of the invention the flexible carrier sheet is adapted to be removed from the product of step (iii) to give the shaped component. In this case the flexible carrier sheet should be made of a material that does not degrade during step (ii) of the method of the invention, i.e. a material that does not change phase from the solid to the liquid, that does not adhere to the platens during the pressing, and is removeable from the product of step (iii) in step (iv). The flexible carrier sheet is preferably a woven or non-woven fabric sheet, a woven metallic wire sheet, or a paper sheet. An example of a suitable material for the manufacture of a flexible carrier sheet is a non-woven polyester sheet with a melting point in excess of 190°C, preferably in excess of 200°C. The flexible carrier sheet may be impregnated or coated with a release substance which facilitates removal of the flexible carrier sheet from the product of step (iii) in step (iv). In another embodiment of the invention, the flexible carrier sheet is adapted to form part of the shaped component, i.e. step (iv) falls away. In this case the flexible carrier sheet should be made of a material that bonds to the substantially dry resinated feedstock during step (ii). The flexible carrier sheet may be a sheet of an inert fibrous material, e.g. glass fibre, impregnated or coated with a suitable thermosetting resin or a precursor thereof, the resin being in a latent condition, and being adapted to set at the temperature of step (ii) to bond the flexible carrier sheet to the substantially dry resinated feedstock in the formation of the shaped component. The flexible carrier sheet may also be a sheet of a woven or non-woven plastics material which melts at the temperature of step (ii) to bond to the substantially dry resinated feedstock in the formation of the shaped component. Examples of suitable plastics materials are polyethylene and polypropylene. The length and width of the flexible carrier sheet depends upon the shaped component being made. For example a flexible carrier sheet for the manufacture of a panel may be 2 440mm x 1 220m; a flexible carrier sheet for the manufacture of a roof tile may be 450mm x 350mm; while a flexible carrier sheet for the manufacture of roof sheeting may be up to 6m long. The material in the feedstock may optionally be chemically modified prior to resination, or may be impregnated with a mineral or vegetable oil prior to or during resination. Preferably, the substantially dry resinated feedstock is prepared according to a method disclosed in any of South African Patents Nos. 95/9111, 95/9112, 97/5547 or 98/1160 or in either of South African Patent Applications Nos. 98/5133 or 98/5134. In step (ii) suitable conditions of temperature are a temperature of from 130°C to 230°C inclusive, preferably a temperature of from 180°C to 220°C inclusive, and of pressure are a pressure of from 20 to 75 kg/cm 2 inclusive, preferably from 50 to 70kg/cm 2 inclusive. The method of the invention may include an additional step: (v) when a hydraulic binder is used, introducing water into the shaped component to hydrate the hydraulic binder. According to a second aspect of the invention, there is provided a flexible carrier sheet for use in the method set out above. BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a schematic view of an embodiment of the method of the invention. DESCRIPTION OF EMBODIMENTS The crux of the invention is that a shaped component is made from a substantially dry resinated feedstock which is placed on a flexible carrier sheet prior to moulding between the platens of a press. The substantially dry resinated feedstock comprises a material selected from a group consisting of particles or fibres of a lignocellulosic material, particles of an exfoliated vermiculite, and particles of an expanded perlite, which material has been resinated with a thermosetting resin, optionally combined with a thermoplastic resin, or a precursor of either thereof, the resin being in a latent condition, i.e. the resin not being polymerised or set, and optionally a hydraulic binder. The substantially dry resinated feedstock may be produced by the method disclosed in South African Patent No. 95/9111 which is incorporated herein by reference. This method is a method of preparing particles of a lignocellulosic material for the manufacture of a finished product which includes the steps of: (a) chemically modifying the lignocellulosic material by impregnating the lignocellulosic material with an impregnating composition comprising a dicarboxylic anhydride or a tricarboxylic anhydride dissolved in a suitable non-aqueous solvent; (b) applying to the particles an adhesion promoter to promote the adherence of a thermoplastic resin to the surfaces of the particles of lignocellulosic material; (c) applying to the particles a thermoplastic resin in dry powder form, so that after the application of the adhesion promoter, the thermoplastic resin adheres to the surfaces of the particles of lignocellulosic material, the thermoplastic resin having been surface modified by irradiation or by fluorination; and d) after step (a) or step (c), removing the solvent. The thermoplastic resin may be replaced by or mixed with a thermosetting resin. Alternatively, the substantially dry, resinated feedstock may be produced by the method disclosed in South African Patent No. 95/9112 which is incorporated herein by reference. This method is a method of preparing particles of an exfoliated vermiculite for the manufacture of a finished product which includes the steps of: (a) if necessary chemically modifying the vermiculite by impregnating the vermiculite with an impregnating composition comprising a dicarboxylic anhydride or a tricarboxylic anhydride dissolved in a suitable non-aqueous solvent; (b) if necessary applying to the particles an adhesion promoter to promote the adherence of a resin to the surfaces of the particles of vermiculite; (c) resinating the particles of vermiculite by either: (i) applying to the particles a thermoplastic resin in dry powder form, so that after the application of the adhesion promoter, the thermoplastic resin adheres to the surfaces of the particles of vermiculite, the thermoplastic resin having been surface modified by irradiation or by fluorination; or (ii) including in the impregnating composition of step (a) an isocyanate thermosetting resin dissolved in a suitable compatible solvent; or (iii) applying to the particles a dry powder novolac thermosetting resin and if necessary a catalyst therefor so that after the application of the adhesion promoter, the dry powder novolac thermosetting resin adheres to the surfaces of the particles of vermiculite; and (d) if necessary after step (c), removing any solvent present. Further alternatively, the substantially dry, resinated feedstock may be produced by the method disclosed in South African Patent No. 97/5547 which is incorporated herein by reference. This method is a method of making a material for subsequent formation into a composite product which method includes the steps of: (1) impregnating particles of an exfoliated vermiculite with an impregnating composition comprising a first thermosetting resin, an extending liquid for the first thermosetting resin, if necessary a catalyst for the first thermosetting resin, and a colouring agent for the particles; (2) removing the extending liquid; (3) subjecting the impregnated particles to suitable conditions to polymerise or cross-link the first thermosetting resin: and (4) coating the particles of step (3) with a binder composition comprising a second thermosetting resin and if necessary a catalyst for the second thermosetting resin; to give the material. Further alternatively, the substantially dry, resinated feedstock may be produced by the method disclosed in South African Patent No. 98/1160 which is incorporated herein by reference. This method is a method of preparing a starting material for the subsequent manufacture of a finished product from a feedstock selected from the group consisting of a lignocellulosic material, exfoliated vermiculite, expanded perlite, and a mixture of two or three thereof, which method includes the steps of: (1) providing the feedstock in the form of substantially dry finely divided lignocellulosic fibres, or substantially dry finely divided exfoliated vermiculite particles, or substantially dry finely divided expanded perlite particles, or a mixture of two or three thereof; and (2) mixing the feedstock with: (a) a suitable amount of a thermosetting resin in finely divided dry powder form, and (b) a suitable amount of a hydraulic binder in finely divided dry powder form; to give the starting material. Further alternatively, the substantially dry, resinated feedstock may be produced by the method disclosed in South African Patent Applications Nos. 98/5133 and 98/5134. This method is a method of preparing lignocellulosic particles or exfoliated vermiculite particles, which method includes the steps of: (a) impregnating the lignocellulosic particles or the exfoliated vermiculite particles with an impregnating composition comprising: (i) a mineral oil; and (ii) a liquid thermosetting resin and, if necessary, a catalyst therefor; in the form of a dispersion of a liquid resin in the mineral oil; to give the starting material. The method preferably includes a step, before step (a) or after step (a), of applying to the lignocellulosic particles or to the exfolitated vermiculite particles a thermosetting resin in finely divided dry powder form and, if necessary, a catalyst therefor, so that the thermosetting resin in finely divided dry powder form adheres to the surfaces of the lignocellulosic particles or exfoliated vermiculite particles. In all the possible alternatives of the method of the invention, the feedstock must be substantially dry before being placed on the flexible carrier sheet. Thus, where necessary, any excess solvent or volatiles or the like must be removed prior to the method of the invention. The feedstocks as described above may be used on their own or in a blend of two or more thereof. A preferred resin for use in the method of the invention is, for example, a novolac resin, or a blend of an MDI and a novolac resin, or a blend of a thermoplastic polymer and a novolac resin. The method of the invention will now be described in more detail with reference to Figure 1. In step (i) of the method of the invention, the substantially dry feedstock 10 is passed from a hopper 12 on to a flexible carrier sheet 14 to form a layer 16. It is important that the flexible carrier sheet is made of a material which does not degrade during the pressing step, when it is intended that the flexible carrier sheet be removed from the product of step (iii) to give the shaped component. Examples of suitable flexible carrier sheets are, for example, sheets of a woven or a non-woven fabric, a sheet of a metallic wire, or a paper sheet. The sheet must be flexible so that it can conform to any shape from the flat to a shaped profile, with a minimum amount of disturbance of the feedstock. The material from which the flexible carrier sheet is made should have the attributes that it does not adhere to the platens of the press, preferably it does not change its phase from the solid to the liquid during the pressing step, it should be removable from the finished product after pressing, optionally it should be suitable for reuse, it should be relatively inexpensive, and it should be sufficiently soft so as not to damage the platens of the press. Alternatively, the flexible carrier sheet should be such that it may be left as an integral part of the shaped component produced, by bonding or adhering to it reliably. Examples of suitable flexible carrier sheets are those of lignocellulosic origin such as cotton, linen or hessian which may optionally have been modified by the methods described in South African Patent Application No. 98/5132, i.e. impregnation with a mineral oil and a liquid thermosetting resin, in which case they become an integral part of the shaped component produced and serve also to reinforce it. Alternatively they may be treated with a release agent to make them removable for re-use. Further examples of flexible carrier sheet materials are woven, or non-woven materials manufactured from synthetic fibres such as acrylics, polyesters, polyethylenes, polypropylenes, acrylonitriles and the like, either with melting points typical of those at which the component is pressed, in which case they become a part of the shaped component by being melted into the feedstock, or alternatively having a higher melt temperature than that used in forming the shaped component in which case they are removable, preferably for re-use. Still further examples of materials suitable for the flexible carrier sheet are the inorganic fibres such as glass or ceramic, impregnated with a suitable thermosetting resin. An example of a suitable flexible carrier sheet is a non-woven sheet manufactured from a synthetic fibre which has a melting point higher than the temperature required for the polymerisation of the resin in the feedstock. A specific example is a polyester fibre with a melting point in excess of 190°C, more generally in excess of 200°C. A typical press temperature is in the range of 140 to 180°C, and thus it can be seen that such a polyester fibre will not degrade at the pressing temperature. The flexible carrier sheet may be coated or impregnated with a release substance that facilitates easy release of the flexible carrier sheet from the formed article. Examples of a suitable release substance are a fluorine- based compound such as Scotch Guard by 3M or Teflon by DuPont, or alternatively a cashew nut oil or derivative thereof, or further alternatively a silicone based-product. An example of a suitable flexible carrier sheet which is designed to form part of the shaped component is a 300g/m 2 chopped strand fibreglass mat, pre-impregnated either with a phenol formaldehyde resole resin which is acid catalysed, e.g. Blagden J 2818L and Phencat 10 respectively, in methanol, which methanol is removed before pressing, or an unsaturated polyester resin, e.g. Ultraset 997 by NCS of South Africa catalysed by a latent catalyst e.g. Triganox 29B50 by Akzo Chemie, in methylene chloride, which is removed before pressing. In step (ii) of the method of the invention, the product of step (i), i.e. the combination of the layer 16 of the feedstock and the flexible carrier sheet 14, is placed between a male platen 18 and a female platen 20 of a press. Then, the combination of flexible carrier sheet 14 and layer of feedstock 16 is subjected to suitable conditions of temperature and pressure, for example, a temperature of 130 to 230°C, and a pressure of from 20 to 75kg/cm 2 , to mould the product into a desired shape and to cause the resin to polymerise or set. In step (iii) of the method of the invention, the product of step (ii) is removed from the platens 18, 20 of the press. In step (iv) of the method of the invention, optionally, the flexible carrier sheet 14 is removed from the product of step (ii) to give the shaped component. In step (v) of the method of the invention, optionally water is introduced into the shaped component to hydrate any hydraulic binder present. The method of the invention is of particular application in the production of shaped components such as automotive parts, e.g. door liners, fielded and planed door skins, corrugated roof sheeting, furniture parts and the like. A typical thickness of a shaped component made by the method of the invention is from 2mm to 12mm, more usually from 2,5mm to 8mm.

Claims: CLAIMS 1. A method of making a shaped component from a substantially dry resinated feedstock comprising a material selected from the group consisting of particles or fibres of a lignocellulosic material, particles of an exfoliated vermiculite and particles of an expanded perlite, which material has been resinated with a thermosetting resin, or a precursor thereof, the resin being in a latent condition, and optionally a hydraulic binder, including the steps of: (i) placing the substantially dry resinated feedstock on a flexible carrier sheet; (ii) placing the product of step (i) between the platens of a press and subjecting the product of step (i) to suitable conditions of temperature and pressure to mould the product of step (i) into a desired shape and to cause the resin to polymerise or to set; (iii) removing the product of step (ii) from the press; and (iv) optionally removing the flexible carrier sheet from the product of step (iii) to give the shaped component. 2. A method according to claim 1 wherein the thermosetting resin or precursor thereof is combined with a thermoplastic resin or precursor thereof. 3. A method according to claim 1 or claim 2 wherein the flexible carrier sheet is adapted to be removed from the product of step (iii) to give the shaped component. 4. A method according to claim 3 wherein the flexible carrier sheet is selected from the group consisting of a woven or non-woven fabric sheet, and a woven metallic wire sheet and a paper sheet. 5. A method according to claim 1 or claim 2 wherein the flexible carrier sheet is adapted to form part of the shaped component. 6. A method according to claim 5 wherein the flexible carrier sheet comprises a sheet of an inert fibrous material impregnated or coated with a suitable thermosetting resin or a precursor thereof, the resin being in a latent condition, and being adapted to set at the temperature of step (ii) to bond the flexible carrier sheet to the substantially dry resinated feedstock in the formation of the shaped component. 7. A method according to claim 5, wherein the flexible carrier sheet comprises a sheet of a woven or non-woven plastics material which melts at the temperature of step (ii) to bond to the substantially dry resinated feedstock to form the shaped component. 8. A flexible carrier sheet for use in a method of making a shaped component from a substantially dry resinated feedstock comprising a material selected from the group consisting of particles or fibres of lignocellulosic material, particles of an exfoliated vermiculite and particles of an expanded perlite, which material has been resinated with a thermosetting resin, or a precursor thereof, the resin being in a latent condition, and optionally a hydraulic binder, the method including the steps of: (i) placing the substantially dry resinated feedstock on a flexible carrier sheet; (ii) placing the product of step (i) between the platens of a press and subjecting the product of step (i) to suitable conditions of temperature and pressure to mould the product of step (i) into a desired shape and to cause the resin to polymerise or to set; (iii) removing the product of step (ii) from the press; and (iii) optionally removing the flexible carrier sheet from the product of step (iii) to give the shaped component. 9. A flexible carrier sheet according to claim 8 wherein the thermosetting resin or precursor thereof is combined with a thermoplastic resin or precursor thereof. 10. A flexible carrier sheet according to claim 8 or claim 9 wherein the flexible carrier sheet is adapted to be removed from the product of step (iii) to give the shaped component. 11. A flexible carrier sheet according to claim 10 wherein the flexible carrier sheet is selected from the group consisting of a woven or non-woven fabric sheet, a woven metallic wire sheet, and a paper sheet. 12. A flexible carrier sheet according to claim 8 or claim 9 wherein the flexible carrier sheet is adapted to form part of the shaped component. 13. A flexible carrier sheet according to claim 12 wherein the flexible carrier sheet comprises a sheet of an inert fibrous material impregnated or coated with a suitable thermosetting resin or a precursor thereof, the resin being in a latent conditions, and being adapted to set at the temperature of step (ii) to bond the flexible carrier sheet to the substantially dry resinated feedstock in the formation of the shaped component. 14. A flexible carrier sheet according to claim 12 wherein the flexible carrier sheet comprises a sheet of a woven or non-woven plastics material which melts at the temperature of step (ii) to bond to the substantially dry resinated feedstock in the formation of the shaped component.

Inventors: SYMONS MICHAEL WINDSOR, SYMONS, MICHAEL, WINDSOR
Applicants: SYMONS MICHAEL WINDSOR, WINDSOR TECHNOLOGIES LTD, SYMONS, MICHAEL, WINDSOR, WINDSOR TECHNOLOGIES LIMITED
Application year: 1999
Main classification: H01R
IPC codes: B29C70