Patent GB-1414361-A (GB)
Title: Method of producing synthetic resin-impregnated paper
IPC: D21H17/35
Filed: 1973-06-21
Abstract: 1414361 Laminates ROHM GmbH 21 June 1973 [24 June 1972] 29609/73 Heading B5N [Also in Division D2] In a method of producing synthetic resin impregnated paper, a dispersion of a non-ionic synthetic resin which contains both a cationic dispersing agent and a non-ionic dispersing agent is added in an amount of at least 30% by weight (calculated as the dry weight of the synthetic resin and based on the dry fibre weight of the paper pulp). The paper may be glued to hardboard or press board panels to produce composite panels for use in the furniture industry, interior decorating or shop fittings. An intermediate layer may be inserted between the supporting panel and the paper layer and is preferably abraded prior to insertion. The non-ionic synthetic resins are derived solely from neutral monomers which do not form salts in acid or alkaline aqueous media and include the esters of acrylic and methacrylic acid, such as methyl, ethyl, butyl or 2-ethylhexyl acrylate, methyl, ethyl, butyl, hexyl or decyl methacrylate, vinyl esters such as vinyl acetate or vinyl propionate, vinyl chloride, vinylidene chloride, acrylonitrile and methacrylonitrile, styrene and its homologues, butadiene, chlorobutadiene, isoprene, ethylene, propylene or mixtures thereof. Advantageously, synthetic resins containing groups capable of cross-linking may be used, which groups may be incorporated by using units of methylol acrylamide or methylol methacrylamide or their esters, acrylamide or methacrylamide, or hydroxylalkyl esters of acrylic or methacrylic acid. These units constitute 0À2 to 12% by weight of the synthetic resin. The corresponding ethers, e.g. methoxymethyl acrylamide or butoxymethyl methacrylamide may similarly be employed. Monomers which renders the resins hydro. phobic may also be incorporated since they increase the affinity of the resins for the fibres. Possible monomers include those which contain aromatic side groups or aliphatic side groups with at least 4 carbon atoms, e.g. butyl, hexyl, decyl or dodecyl esters of acrylic or methacrylic acid or the vinyl esters of butyric acid or of higher fatty acids or styrene and its homologues. The cationic dispersing agent may be C 12 -C 14  fatty amine hydrochloride, cocoamine hydrochloride or cetyl trimethyl ammonium chloride, and can be used from the beginning of the polymerization, in quantities of 0À5-2À5%, based on the aqueous phase. The non-ionic dispersing agents may have a surface active character such as ethoxylated fatty acids, fatty alcohols or alkyl phenols. Alternatively, protective colloids may be employed such as polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone or polyalkylene oxides and block copolymers of ethylene oxide and propylene oxide. The amount used is in the range 1-4%. The preferred initiators do not introduce anionic groups into the polymer. Thus hydrogen peroxide or azo-bis-isobutyronitrile is more suitable than potassium or ammonium persulphate or azo-bis-cyanovaleric acid. The fibrous pulp preferably contains at least 30% natural cellulosic fibres e.g. ground cotton fibres, the remainder being synthetic cellulose fibres. The pump may contain fillers such as kaolin or titanium dioxide.