GB1558964A

GB1558964A - Process for preparation of non-combustible decorative panels

Info

Publication number: GB1558964A
Application number: GB36230/75A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-08-26
Filing date: 1976-08-26
Publication date: 1980-01-09

Description

(54) PROCESS FOR PREPARATION OF NON-COMBUSTIBLE DECORATIVE PANELS (71) I, GEORGE LESLIE ROBINSON, a British Subject, of 239 Ditchfield Road, Hough Green, Widnes, Cheshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for preparing non-combustible (as hereinafter

defined), decorative, composite panels and to such panels w henp r rv ~ t the Dreeenf t, o ERRATUM SPECIFICATION NO 1558964 Page 3, line 47, for commerically read commercially for Erode read Evode Bas 74096/11 THE PATENT Bas 74096/11 26 Februa7y 1980 --.-..,. rerm 'non-combustible" panci ...paepane)or a substrate which has a class 0 non-combustibility. A material having a class 0 non-combustibility is defined in Section E14 of the Building Regulations 1965 (as amended) as having an index performance (I) less than 12 and a sub-index (i) not exceeding 6, Section E14 of the Building Regulations 1965 (as amended) has now been superseded by Section E15 of the Building Regulations 1972 (as amended), although the index performance (I) and sub-index (ii) values for class 0 non-combustibility remain the samc.

A synthetic, resin-impregnated, fibrous layer of 5 to 11 mils (0.13 to 0.28 millimetres), for example 5 to 10 mils (0.13 to 0.26 millimetres)"in thickness adhered to a substrate by the process of the present invention will, when the composite panel so produced is subjected to the flame propagation test (B. S. 476, part 6, 1968) only scorch in the area to which the flame is applied. However, a fibrous layer substantially thicker than 11 mils (0.28 millimetres) will, when adhered to a substrate by the process of the present invention and subjected to the flame propagation test, probably scorch over a greater area than that to which the flame is applied and may possibly ignite.

Suitable non-combustible substrates for use according to the present invention include plasterboard, asbestos and other inorganic non-combustible panels as well as hardboard, plywood and chipboard which have been treated in order to render thcm non-combustible.

The substrates may be used in either the unsanded or sanded form. However, if an unsanded substrate is used, the pressure necessary to bond the synthetic, resin-imprenated, fibrous laver to the substrate and provide a composite panel with a satisfactory fimsh will generally be higher than that needed for a sanded substrate. The reason for this is that with an unsanded substrate the pressure needed will not only have to be sufficient to bond the fibrous layer to the substrate but will also have to be sufficient to smooth out any imperfections in the surface of the substrate being coated. The increase in pressure generally needed to remove (54) PROCESS FOR PREPARATION OF NON-COMBUSTIBLE DECORATIVE PANELS (71) I, GEORGE LESLIE ROBINSON, a British Subject, of 239 Ditchfield Road, Hough Green, Widnes, Cheshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for preparing non-combustible (as hereinafter defined), decorative, composite panels and to such panels whenever prepared by this process.

At the present time, it is common to treat the surface or surfaces of panels used, for example in or for the building industry, to manufacture prefabricated panels for buildings by applying a paint or similar liquid finish. There is, however, a need for a non-combustible or at least flame-retardant, decorative panel which needs no such treatment of the surface when used yet offers a much wider range of patterns and finishes on both surfaces, or a single surface if required.

According to the present invention there is provided a process for preparing a noncombustible (as hereinafter defined), decorative, composite panel which comprises coating a surface of a non-combustible (as hereinafter defined) substrate with a resin-based adhesive, and pressing a synthetic, resin-impregnated, fibrous layer having a thickness of up to 11 mils and the adhesive coated surface of the substrate together at a pressure of at least 30 lbs/in' and at a temperature of at least 60 F to bond the fibrous layer to the substrate and thereby produce a non-combustible (as hereinafter defined), decorative, composite panel.

As used herein in connection with the present invention, the term"non-combustible" refers to a composite panel or a substrate which has a class 0 non-combustibility. A material having a class 0 non-combustibility is defined in Section E14 of the Building Regulations 1965 (as amended) as having an index performance (I) less than 12 and a sub-index (ii) not exceeding 6. Section E14 of the Building Regulations 1965 (as amended) has now been superseded by Section E15 of the Building Regulations 1972 (as amended), although the index performance (I) and sub-index (i,) values for class 0 non-combustibility remain the same.

A synthetic, resin-impregnated, fibrous layer of 5 to 11 mils (0.13 to 0.28 millimetres), for example 5 to 10 mils (0.13 to 0.26 millimetres)"in thiclçness adhered to a substrate by the process of the present invention will, when the composite panel so produced is subjected to the flame propagation test (B. S. 476, part 6,1968) only scorch in the area to which the flame is applied. However, a fibrous layer substantially thicker than 11 mils (0. 28 millimetres) will, when adhered to a substrate by the process of the present invention and subjected to the flame propagation test, probably scorch over a greater area than that to which the flame is applied and may possibly ignitc.

Suitable non-combustible substrates for use according to the present invention include plastcrboard, asbestos and other inorganic non-combustible panels as well as hardboard, plywood and chipboard which have been treated in order to render them non-combustible.

The substrates may be used in either the unsanded or sanded form. However, if an unsanded substrate is used, the pressure necessary to bond the synthetic, resin-impregnated, fibrous layer to the substrate and provide a composite panel with a satisfactory fimsh will generally be higher than that needed for a sanded substrate. The reason for this is that with an unsanded substrate the pressure needed will not only have to be sufficient to bond the fibrous layer to the substrate but with also have to be sufficient to smooth out any imperfections in the surface of the substrate being coated. The increase in pressure generally needed to remove any imperfections in the surface of the substrates, for example in the surface of unsanded substrates, may be partially or completely avoided by utilizing an adhesive of thicker consistency. the use of such an adhesive will aid in partially or completely filling any imperfections, for example valleys or low spots, in the substrate thereby helping to avoid subsequent air gaps and consequent blistering in the finished panel.

If asbestos is used as the substrate for the decorative, composite panels of the present invention, it may be used in either a compressed or semi-compressed, preferably a semicompressed, form.

In order to bond the synthetic, resin-impregnated, fibrous layer to an asbestos, plasterboard, hardboard, plywood or chipboard substrate, a pressure of not less than 301bs/in2 is used. More preferably the pressures used are in the range of 30 to 2001bsZin2. Still more preferably the pressures used are in the range of 30 to 801bs/in2 and especially preferred are pressures in the range of 40 to 451bs/in2. The pressures used will, of course, depend on such factors as the type of substrate used, the type of press used to apply the pressure needed to bond the fibrous layer to the substrate and, in the case of asbestos substrates, on whether the asbestos is used in the compressed or semi-compressed form. If semi-compressed asbestos is used, a pressure of 100lbs/in'is preferably not exceeded. Greater adhesive penetration is achieved with the semi-compressed forms of asbestos. For plasterboard a pressure of from 30 to 801bs/in2 is preferably used, especially a pressure of 30 to 401bs/in.

Plasterboard is commonly marketed in two forms. The first of these is known as wallboard, which is usually inch (9.5mm) or W inch (12. 7mm) in thickness and sold, for example, in panels measuring 8ft by 4ft or similar large sizes. The second form of plasterboard commonly marketed is known as baseboard, which is usually ss inch (9.5mm) in thickness and sold, for example, in panels measuring 4ft by 3ft or similar small sizcs for ceiling panels.

Before use in the process of the present invention the surface of the substrate to be coated with the adhesive should preferably be cleaned to render it dust free and all grease or oil should be removed.

The pressing together of the substrate and the fibrous layer can be achieved using either a cold press or a hot press, for example a hot How line press or single-or-multi-daylight press. A hot flow line press is a press operating at elevated temperature, having a short cycle of operation and which can thereby produce single composite panels or laminates rapidly as opposed to the longer cycle single-or multi-daylight presses which are batch loaded.

The press may be either a flat press, i. e. a platen press, or a roller press. A vacuum press may also be used, although this type of press is much less preferred. If a cold press is used, the operating temperature, i. e. the temperature of the surrounding environement, is likely to be in the range of 60 to 80 F. If, however, a hot press is used, the operating temperature can be in the range of 80 to 285 F. A hot press will, preferably, be operated at a temperature of 190 to 285 F but 1 0 to 194 F is especially preferred for a standard multi-daylight press. A hot press is preferably operated at a temperature of 190 to 285 F. (150 to 194 F in the case of a standard multi-daylight press) since it would not be economical to supply energy to raise the temperature of the press to just above that of the surrounding environment, i. e. to raise the press to a temperature in the range of 80 F to 150 F. Hot pressing is particularly preferred since the drying time of the coated panel is thereby reduced. If poor drying conditions prevail, e. g. a cold, damp or very humid atmosphere, too long a drying time or the coated panels are stacked too cl sely together during drying, moisture from the adhesive may be retained in the substrate for an unsatisfactory length of time and an unsatisfactory panel may be obtained. For example, if plasterboard is used as the substrate, the retention of moisture may cause the surface material of the plasterboard to separate from the main body of the board.

When using a hot press, it is important that the substrates have, prior to applying the adhesive, a moisture content of not more than 12% by weight. For asbestos substrates this upper limit for the moisture content is particularly important when hot presses are used.

Thicker boards are more susceptible than thin boards in holding moisture. If substrates having a moisture content above 12% by weight are used on hot presses, subsequent blistering of the paneis on applying the fibrous laycr is likely to result due to the production of steam within the panel and this blistering of the panels is more likely to occur with the thicker asbestos boards due to their susceptibility for holding moisture.

The upper limit of 12% by weight for the moisture content of the substrates is a preferred limit when cold presses are used since it is less likely that blistering will result.

Substrates having a moisture content of not more than 12% by weight may suitably be prepared by air drying the panels prior to applying the adhesive.

The fibrous layer used in the process according to the present invention is preferably 5 to 1 I mils (0. 13 to 0.28mms), for example 5 to 10 mils (0. 13 to 0.28mms) in thickness. At thicknesses much greater than this the fibrous ayer would be such that, when bonded to a substrate, the decorative panel so produced is ikc) y to be rendered intlammabic. Further, the fibrous layer may be coloured, tinted or printed and may be plain, textured or glazed, e. g. using a cross-linked acrylic polymer with an amino-plastics material as lacquers. The fibrous layer may be lacquered with one or more layers of lacquer (each layer may be different) and this may be carried out during or after the impregnation of the fibrous layer with resin.

A variety of lacquers can be used for partially or fully finished decorative, composite panels and no further application is necessary to produce hard-wearing, smooth, decorative panels.

Suitable lacquers include nitrocellulose lacquers, polyurethane lacquers, polyester lacquers and acid catalysed lacquers. Examples of acid catalysed lacquers are acid catalysed melamine formaldehyde resins or lacquers based on ureaformaldehyde/alkyd combinations or melamineformaldehyde/alkyd combinations.

When hot presses are used, the resin of the fibrous layer may flow under the influence of the heat and pressure to produce a smooth surface. In this instance, to ensure faultless surfaces, it is necessary that clean flat cauls are used on the press and these are therefore preferably kept for this purpose only.

Suitable synthetic, resin-impregnated, fibrous layers for use in the composite panels of the present invention include paper based materials. A particularly suitable synthetic, resin impregnated, fibrous layer for use in the composite panels of the present invention is marketed as"Catafoil" ("Catafoil"is a Trade Mark). Further, resin-impregnated papers at present available and having a density of 125 to 205, e. g. approx. 125g/m2 are also suitable for use as the fibrous layer.

Examples of suitable resin-impregnated, paper based materials at present available and sold under the name"Catafoil"are given in the following table.

TABLE

Thickness Substance grams mils millimetres per sq. metre 11 0.28 205 11 0.28 210 5 0.13 125 80. 20175 60. 15145 50. 13125 0. 20 170 8 0. 20 175 Suitablc adhesives (especially for hot pressing) for bonding the synthetic, resinimpregnated, fibrous layer to the substrate are, for example, PVA (polyvinyl acetate), rcsorcinol-based adhesives or other similar, e. g. urea/melamine, urea,'formaldehyde or epoxy, resin-based adhesives and these may be applied to the substrate using either a manual or mechanical spreader. The adhesives may be either 1 part or 2 part adhesives. A I part adhesive is an adhesive in which a single composition is present and is applied to at least one of the surfaces to be bonded. A 2 part adhesive, however, is an adhesive in which a catalyst is added to the base adhesive in order to initiate setting ; the catalyst uoally being added to the base adhesive before application to at least one of the surfaces to be bonded. Examples of suitable adhesives sold commerically are"Resin W" (manufactured by Erode Ltd), which is a 1 part adhesive having a setting time of approximatety 1 hour at ambient temperature, and a P. V. A. adhesive marketed as a"2 part thermosetting emulsion adhesive". P. V. A. self- extinguishing adhesive made for cold platen pressing is more preferable than Resin W referred to above. Typical setting times for P. V. A. adhesives are approximately 1. 5 minutes at 285 f on Flow line presses and approximately 5 minutes at 105 F on multi-daylight presses but temperatures and pressings arc variabte depending on the adhesive and manufacturer.

If a cold flat press is used to bond the fibrous layer to the substrate, the preferred adhesive is a urea-resin 2 part adhcsive, and free air passage between the panels during drying should preferably be maintained to allow the substrate to dry out. Plasterboard is considered less suitablc for use in cold press bondit,,.

When roller presses are used the preferred adhesive is a sclf-extinguishing P. V. A. adhesive (1 part) and the preferred fibrous layer is a single lacquered"Catafoil"tayer or similar flcxiblc fibrous laver. Whcn roller presses are used, flexible fibrous layers are preferred to avoid cracking and these may be formutated by having piasticizers embedded therein.

When pressing the fibrous layer and adhesive coated substrate, the pressing should preferably be for a time sufficient to cause the adhesive to penetrate the surface of the substrate, thereby ensuring an adequate bond between the substrate and fibrous) ayer. If the time is not sufficient for the adhesive to penetrate the surface of the substrate and the substrate has a powdery surface, e. g. asbestos, a poor bond will be formed between the substrate and the fibrous layer. Of course, as indicated previously, speed is preferable for panels utilizing plasterboard as substrate in order to avoid the surface paper delaminating away from the plaster base due to oversaturation.

Panels produced according to the present invention may be of different sizes, and may be used without further surface treatment. Because decorative fibrous layers having a wide range of colours, patterns and textured designs, glossy or matt in finish, may be used, it will be appreciated that there is considerable scope for mass production or for production to individual tastes.

The present invention will now be further illustrated by way of the following examples: Example 1 A decorative panel was prepared using an 8ft by 4ft semi-compressed asbestos sheet (4.5mm in thickness) having approximately 11 % by weight moisture content and coating one surface of this sheet with a film of a 2 part PVA adhesive marketed by ;'National"adhesives manufacturers. A layer of double lacquered coated and textured"Catafoil"approximately 8 mils (0.20 mms) in thickness was then applied to the adhesive coated surface of the asbestos sheet and the combination pressed in a hot press at a pressure of 40 to 45 lbs/in', a temperature of 280 F, and for a period of 1.5 to 2.0 minutes. A decorative panel was thereby produced which, on testing by the fire propagation test (B. S. 476, part 6,1968), was found to have class O non-combustibility.

Example 2 A decorative panel was produced by coating one surface of an 8ft by 4ft plasterboard sheet inch thick wallboard) with a film of a 2 part PVA adhesive marketed by"National" adhesive manufacturers. To the adhesive coated surface of the plasterboard was then applied a layer of"Catafoil"approximately 5 mils (0.13mms) thickness and having a single lacquer coating. The combination was then pressed in a hot press at a pressure of 40 to 45] bs/ in', a temperature of 240 F. and for a period of 1.5 to 2.0 minutes.

A decorative panel was thereby produced which on testing by the fire propagation test (B. S. 476, part 6,1968), was found to have class 0 non-combustibility.

Example 3 A decorative panel was prepared by coating one surface of an 8ft by 4ft plasterboard sheet (2 inch in thickness) with a 1 part self-extinguishing PVA adhesive. A layer of"Catafoil" approximately 5 mils (0.13mms) in thickness and having a single lacquer layer was then applied to the adhesive coated surface of the plasterboard sheet and the combination cold pressed at ambient temperature using a roller press at a pressure of approximately 381bs/in2.

A decorative panel was thereby produced which on testing by the fire propagation test (B. S.

476, part 6,1968), was found to have class 0 non-combustibility.

Claims

WHAT I CLAIM IS: 1. A process for preparing a non-combustible (as hereinbefore defined), decorative, composite panel, which comprises coating a surface of a non-combustible (as hereinbefore defined) substrate with a resin-based adhesive, and pressing a synthetic, resin-impregnated, fibrous layer having a thickness of up to 11 mils and the adhesive coated surface of the substrate together at a pressure of at least 30 lbs/in'and at a temperature of at least 60 F to bond the fibrous layer to the substrate and thereby produce a non-combustible (as hereinbefore defined), decorative, composite panel.
2. A process as claimed in claim 1, in which the pressure is from 30 to 200 lbs/in'
3. A process as claimed in claim 2, in which the pressure is from 30 to 80 lbsXin2.
4. A process as claimed in claim 3, in which the pressure is from 40 to 45 lbs/in'.
5. A process as claimed in any of claims 1 to 4, in which the substrate is asbestos or plasterboard.
6. A process as claimed in any of claims 1 to 4, in which the substrate is plywood, hardboard or chipboard which has been rendered non-combustible (as hereinbefore defined).
7. A process as claimed in any of claims 1 to 6, in which the pressing together of the synthetic, resin-impregnated, fibrous layer and the adhesive coated surface of the substrate is carried out in a cold press.
8. A process as claimed in claim 7, in which the cold press is operated at a temperature of 60 to 80 F.
9. A process as claimed in any of claims 1 to 6, in which the pressing together of the synthetic, resin-impregnated, fibrous layer and the adhesive coated surface of the substrate is carried out in a hot press.
10. A process as claimed in claim 9, in which the hot press is operated at a temperature of 80 'to 285 F.
11. A process as claimed in Claim 10, in which the hot press is operated at a temperature of 190 to 285 F.
12. A process as claimed in any of claims 9 to 11, in which the hot press is a hot flow line press or a single-or multi-daylight press.
13. A process as claimed in claim 12, in which the hot press is a multi-daylight press operated at a temperature of 150 to 194 F.
14. A process as claimed in any of claims 9 to 13, in which the substrate has a moisture content of not more than 12% by weight.
15. A process as claimed in claim 14, in which the substrate is asbestos.
16. A process as claimed in claim 1, in which the substrate is semi-compressed asbestos and the pressure is not more than 100 lbs/in2.
17. A process as claimed in claim 1, in which the substrate is plasterboard and the pressure is from 30 to 80 lbs/in.
18. A process as claimed in claim 17, in which the pressure is from 30 to 40 Ibs/in2
19. A process as claimed in any of claims 1 to 11,16 or 17, in which the resin-based adhesive is a PVA adhesive or a resorcinol-based adhesive.
20. A process as claimed in any of claims 1 to 11,16 or 17, in which the resin-based adhesive is a urea/melamine or urea/formaldehyde resin-based adhesive.
21. A proces as claimed in any of claims 12 to 15 or 18, in which the resin-based adhesive is a PVA adhesive or a resorcinol-based adhesive.
22. A process as claimed in any of claims 12 to 15 or 18, in which the resin-based adhesive is a urea/melamine or urea/formaldehyde resin-based adhesive.
23. A process as claimed in any one of claims 1 to 18, in which the resin-based adhesive is an epoxy adhesive.
24. A process as claimed in any of claims 1 to 23, in which the thickness of the synthetic, resin-impregnated, fibrous layer is from 5 to 11 mils.
25. A process as claimed in any of claims 1 to 11,16,17,19 or 20, in which the thickness of the synthetic, resin-impregnated, fibrous layer is from 5 to 10 mils.
26. A process as claimed in any of claims 12 to 15, 18 or 21 to 23, in which the thickness of the synthetic, resin-impregnated, fibrous layer is from 5 to 10 mils.
27. A process as claimed in any of claims 1 to 26, in which the panel has at least one layer of lacquer on the surface of the fibrous layer remote from the substrate.
28. A process as claimed in claim 1 and substantially as hereinbefore described with reference to Example 1.
29. A process as claimed in claim 1 and substantially as hereinbefore described with reference to Example 2 or Example 3.
30. A non-combustible (as hereinbefore defined), decorative, composite panel whenever produced by a process as claimed in any of claims I to 11,16,17,19,20,25 or 29.
31. A non-combustible (as hereinbefore defined), decorative, composite panel whenever produced by a process as claimed in any of claims 12 to 15, 18, 21 to 24 or 26 to 28.