Patent GB-1021887-A (GB)
Title: Coating compositions for paper
Inventor: BRUENING DIETHELM
IPC: D21H19/60
Filed: 1962-12-20
Abstract: Compositions for coating paper comprise an alkaline casein solution and a polymer dispersion obtained by emulsion polymerization of a mixture of 90 to 99.9 weight per cent of one or more water-insoluble saponifiable ethylenically unsaturated compounds and 10 to 0.1 weight per cent of one or more ethylenically unsaturated compounds which yield water-soluble polymers, at a pH of 3 to 6.5 in the presence of 0.3 to 5 weight per cent based on the monomers of one or more alkali metal or ammonium salts of sulphuric acid half esters of reaction products of ethylene oxide and/or propylene oxide with compounds containing hydroxyl, carboxyl, amide or imide groups, any adjustment of pH to a value above 6.5 being effected only after polymerization is completed.  Specified watersoluble monomers are acrylic, methacrylic, maleic, fumaric, a -ethylacrylic, crotonic, a -chloracrylic and vinyl sulphonic acids, acrylamide, methacrylamide, vinyl lactams such as N-vinyl pyrrolidone, C-vinyl amines, N-vinyl amines and salts thereof.  Specified saponifiable compounds are vinyl acetate, vinyl propionate, acrylic and methacrylic esters of alcohols containing 1 to 4 carbon atoms, maleic and itaconic esters and N,N-dibutylacrylamide. The monomer mixture may also comprise minor proportions of unsaponifiable compounds such as vinyl ethers, vinyl halides, vinylidene halides, butadiene, isoprene and styrene; and water soluble compounds which yield water-insoluble polymers, e.g. acrylonitrile, methacrylonitrile and acrolein.  The emulsifiers may be derived from fatty alcohols, fatty acids, resin acids, amides and imides of carboxylic and sulphonic acids, alkyl phenols and alkyl naphthols, and may be used alone or together with other emulsifiers and stabilizers, e.g. alkali metal and ammonium salts of carboxylic and sulphonic acids or sulphuric acid half esters, polyvinyl alcohol, polyvinyl pyrrolidone and polyacrylamide. amide.  The casein may be dissolved in aqueous ammonia, ethanolamine or caustic soda.  The coating compositions may also contain soya bean meal, starches, water-soluble cellulose derivatives, dispersing agents, optical brighteners, dyes and pigments, e.g. kaolin, barium sulphate, calcium carbonate, titanium dioxide and calcium sulphoaluminate.  Examples describe (1) the preparation of a dispersion by copolymerizing sodium vinyl sulphonate, acrylic acid, vinyl propionate and n-butyl acrylate in the presence of potassium persulphate and the sodium sulphate half ester of an ethylene oxide-iso-octylphenol condensate; and coating compositions comprising caustic soda solubilized casein, kaolin and aqueous dispersions prepared as in Example (1) of copolymers of sodium vinyl sulphonate and acrylic acid with (1) vinyl propionate and n-butyl acrylate, (2 and 3) vinyl propionate and (4) isobutyl acrylate and t.-butyl acrylate.ALSO:Paper may be coated with compositions comprising an alkaline casein solution and a polymer dispersion obtained by emulsion polymerization of a mixture of 90-99,9 weight per cent of one or more water-insoluble saponifiable ethylenically unsaturated compounds and 10-0,1 weight per cent of one or more ethylenically unsaturated compounds which yield water-soluble polymers, at a pH of 3-6,5 in the presence of 0,3-5 weight per cent based on the monomers of one or more alkali metal or ammonium salts of sulphuric acid half esters of reaction products of ethylene oxide and/or propylene oxide with compounds containing hydroxyl, carboxyl, amide or imide groups, any adjustment of pH to a value above 6,5 being effected after polymerization is completed.  The compositions may also comprise soya bean meal, starches, water-soluble cellulose derivatives, dispersing agents, optical brighteners, dyes and pigments, e.g. kaolin, barium sulphate, calcium carbonate, titanium dioxide and calcium sulphoaluminate.  Specified monomers yielding water-soluble polymers are acrylic, methacrylic, maleic, fumaric, a -ethyl acrylic, crotonic, a -chloracrylic and vinyl sulphonic acids, acrylamide, methacrylamide, N-vinyl pyrrolidone, C-vinyl pyridines, N-vinyl pyridines and salts thereof.  Specified saponifiable compounds are vinyl acetate, vinyl propionate, acrylic and methacrylic esters of alcohols containing 1-4 carbon atoms, maleic and itaconic esters and N,N-dibutylacrylamide.  The monomer mixture may also comprise minor proportions of unsaponifiable compounds such as vinyl ethers, vinyl halides, vinylidene halides, butadiene, isoprene and styrene; and water-soluble compounds yielding water-insoluble polymers, e.g. acrylonitrile, methacrylonitrile and acrolein.  The casein may be dissolved in aqueous ammonia, ethanolamine or caustic soda. Examples describe the coating of paper with compositions comprising caustic soda solubilized casein, kaolin and dispersions of copolymers of sodium vinyl sulphonate and acrylic acid with (1) vinyl propionate and n-butyl acrylate, (2 and 3) vinyl propionate and (4) isobutyl acrylate and t.butyl acrylate, prepared in the presence of the sodium sulphate half ester of an isooctyl phenol-ethylene oxide condensate.