Patent GB-900182-A (GB)
Title: Coating compositions, and articles coated therewith, comprising a water-insoluble linear polymer and an ammonium salt of a methyl methacrylate copolymer with acrylic and/or methacrylic acid
IPC: C08L33/06
Filed: 1958-12-01
Abstract: Fibrous substrates such as paper-board and chip-board may be coated with compositions comprising dispersions in water of synthetic film-forming polymeric material consisting essentially of (a) a water-insoluble linear addition polymer having a Ti value of not over 30 DEG C. and (b) an ammonium salt of a low average molecular weight copolymer containing 20 to 30% by weight of polymerized acrylic and/or methacrylic acid and 70 to 80% by weight of polymerized methyl methacrylate, the mixture of (a) and (b) containing 90 to 65 parts by weight of the former and 10 to 35 parts by weight of the latter.  The polymer (a) may be a copolymer of butadiene with styrene or acrylonitrile, a polymer of at least one acrylic or methacrylic ester, or a copolymer of an acrylic ester with an alkyl methacrylate, vinyl acetate, styrene, acrylonitrile, methacrylonitrile, vinyl chloride or vinylidene chloride; and specified polymers include copolymers of ethyl acrylate with methyl acrylate, methyl methacrylate, butyl methacrylate, acrylonitrile and styrene; n-propyl acrylate with methyl methacrylate and acrylonitrile; and butyl acrylate with methyl methacrylate, butyl methacrylate, acrylonitrile and styrene.  The salts (b) may be simple ammonium salts or complex zinc ammonium salts.  The compositions may also contain 5 to 20% by weight of polymer solids of zinc oxide of particle size 1 to 100 microns which serves to cross-link the polymers (b) on drying. Examples describe the coating of chipboard with compositions comprising ammonium salts of methyl methacrylate-methacrylic acid copolymers and (1) an ethyl acrylate-methyl methacrylate copolymer and (2) a vinyl acetate-methyl acrylate-ethyl acrylate copolymer; (3) the coating of paper-board with compositions comprising an ammonium salt of a methyl methacrylate-methacrylic acid copolymer and an ethyl acrylate-methyl methacrylate-itaconic acid copolymer; and the formation of coatings from compositions comprising ammonium salts of methyl methacrylate-methacrylic acid copolymers and (4) an ethyl acrylate-methyl methacrylate-methacrylic acid copolymer, (5) a styrenebutadiene copolymer and (6) a vinyl acetate-methyl acrylate-ethyl acrylate copolymer.ALSO:Aqueous coating compositions comprise a dispersion in water of synthetic film-forming polymeric material consisting essentially of (a) a water-insoluble linear addition polymer having a Ti value of not over 30 DEG C. and (b) an ammonium salt of a low average molecular weight copolymer containing 20 to 30% by weight of polymerized acrylic and/or methacrylic acid and 70 to 80% by weight of polymerized methyl methacrylate, the mixture of (a) and (b) containing 90 to 65 parts by weight of the former and 10 to 35 parts by weight of the latter.  The polymer (a) may be a copolymer of butadiene with styrene or acrylonitrile, a polymer of at least one acrylic or methacrylic ester, or a copolymer of an acrylic ester with an alkyl methacrylate, vinyl acetate, styrene, acrylonitrile, methacrylonitrile, vinyl chloride or vinylidene chloride.  The copolymer salt (b) may be a simple ammonium salt or a complex zinc ammonium salt of a copolymer obtained by copolymerizing acrylic and/or methacrylic acid with methyl methacrylate in the presence of a chain transfer agent, e.g. t-dodecyl mercaptan, isopropanol, isobutanol, lauryl alcohol, t-octyl alcohol, carbon tetrachloride, tetrachloroethylene and bromotrichloromethane.  The compositions may also contain 5 to 20% by weight of polymer solids of zinc oxide of particle size 1 to 100 microns, which serves to cross-link the polymers (b) on drying.  The copolymer (b) may be used as emulsifying agent in the preparation by emulsion polymerization or in the dispersion of polymer (a). Specified polymers (a) include copolymers of ethyl acrylate with methyl acrylate, methyl methacrylate, styrene, acrylonitrile and butyl methacrylate; n-propyl acrylate with methyl methacrylate and acrylonitrile; and butyl acrylate with methyl methacrylate, butyl methacrylate, acrylonitrile and styrene.  Examples describe compositions comprising ammonium salts of methyl methacrylate-methacrylic acid copolymers prepared by emulsion polymerization in the presence of sodium lauryl sulphate, ammonium persulphate and bromotrichloromethane and (1) an ethyl acrylate-methyl methacrylate copolymer; (2 and 6) a vinyl acetate-methyl acrylate-ethyl acrylate copolymer; (3) an ethyl acrylate-methyl methacrylate-itaconic acid copolymer; (4) an ethyl acrylate-methyl methacrylate-methacrylic acid copolymer; and (5) a styrene-butadiene copolymer.  The compositions may be used for coating fibrous substrates such as paper, paperboard and chip-board.