Patent GB-939789-A (GB)
Title: Improvements in decorative foam surface covering and process for its production
IPC: C08J9/06
Filed: 1960-07-18
Abstract: 939,789. Decorative coatings. MICHAEL NAIRN & CO. Ltd. July 18, 1960 [July 21, 1959], No. 24882/60. Class 140. A decorative foam layer surface covering having a textured surface is produced by applying at least two liquid foamable thermoplastic resinous compositions containing substantially different amounts of foaming agent to a flexible sheet having a surface with a plurality of areas depressed beneath the surface, at least a portion of each composition being exposed as a part of a decorative design, and heating the compositions to fuse the compositions and decompose the foaming agents thereby causing the compositions to expand. One composition may be applied first to the flexible sheet as a layer covering the entire area of the flexible sheet and the second composition is applied to the layer to cover selected portions of the surface of the layer leaving other portions of the layer exposed. The two compositions may be applied to the flexible sheet such that each covers a portion of the surface of the flexible sheet exclusive to the respective composition. An additional composition containing a foaming agent may be applied to the sheet as a base layer covering the entire area of the sheet, the other compositions being applied on top of the base layer such that each covers a portion of the surface of the base layer exclusive to the respective one of the other compositions, all the compositions containing substantially different amounts of foaming agent. The different compositions may be applied to the sheet as coatings of different thicknesses. The foamable thermoplastic resinous compositions may have viscosities between 200 and 25,000 cps. at 25‹ C. and may be foamable plastisols of vinyl chloride polymer incorporating 50 to 150 parts by weight plasticizer per 100 parts by weight of vinyl chloride polymer, which may contain a respective effective amount of foaming agent which can be decomposed by heating to a temperature of less than 450‹ F. The vinyl chloride polymer may have a specific viscosity measured in a solution of 0.2 gm. resin in 100 ml. nitrobenzene at 20‹ C. of between 0.17 and 0.31. The foaming agent may have a minimum initial decomposition temperature of at least 200‹ F. or of at least the fusion temperature of the vinyl chloride polymer. The depressed areas of the flexible sheet may be depressed at least 5 ml. beneath the surface. A thin clear top layer of soil resistant resinous composition may be incorporated in the covering. Suitable backing sheets are those formed of flexible resinous compositions, e.g. polychloroprene, polyvinyl chloride and acetate, vinyl chloride-vinyl acetate copolymer and butadiene-styrene, woven fabrics such as burlap of, for example, cotton, wool, synthetic and animal fibres, which may be sized, and impregnated felted fibres such as cellulosic, e.g. cotton, rags, wood pulp, and paper, synthetic, animal or mineral fibres, e.g. asbestos fibres. Examples of impregnants are given. The thermoplastic resin may be polystyrene, polymethyl styrene, polybutadiene, polymers and copolymers of acrylic and methacrylic acid and their derivatives, polyvinyl chloride and copolymers of vinyl chloride with ethylenically unsaturated compounds, examples of which are given. Examples are given of plasticizers, diluents, light and heat stabilizers, and pigments which may be present. Typical foaming agents include substituted hydrazides, nitroso and azo compounds, e.g. p,p<SP>1</SP>-oxybis(benzene sulphonyl hydrazide) ; N,N<SP>1</SP> - dimethyl - N,N<SP>1</SP> - dinitroso terephthalamide, dinitrosopentamethylene tetramine and azodiformamide. As shown, web 11 is embossed by roller 12 to produce depressions 17, and passes beneath blade 18 which allows a layer of composition 19 containing foaming agent to be applied to the surface of the web filling the depressions and producing a smooth surface. The coated web passes through a block printing machine having a plurality of printing blocks 26 which are supplied with resinous composition 28 from pots 29 by rollers 30. The printed web passes through oven 31 in which the composition is fused and foamed to produce a patterned coating of raised portions 37 and lower portions 38 corresponding to the printed areas having different amounts of foaming agent contained therein.