Patent GB-917418-A (GB)
Title: Compositions for coating cement products and methods for coating such products
IPC: C09D133/12
Filed: 1959-03-26
Abstract: Formed but uncured cement products are coated with compositions comprising an aqueous dispersion containing (1) a polymer of monoethylenically unsaturated monomers containing 85 to 100 weight per cent of polymerized methyl methacrylate and not more than 2 weight per cent of units imparting hydrophilicity to the polymer and (2) a water-insoluble organic solvent for the polymer which boils in the range 150 DEG  to 255 DEG C. and which is present in amount sufficient to result in the formation of a continuous film on drying said coated product, and the applied coating dried to a non-tacky state at a temperature below 100 DEG C.  The cement products may be sheets, tiles or shingles of asbestos cement, and the compositions may be applied by spraying or flooding.  The polymers may comprise up to 15% of alkyl acrylates, e.g. methyl, ethyl and butyl acrylates, and up to 2% of acrylic, methacrylic or itaconic acid, acrylamide, methacrylamide, b -hydroxyethyl acrylate, b -aminoethyl acrylate, b -N,N-dimethylaminoethyl acrylate or b -hydroxyethyl vinyl ether.  The solvent may be 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-(2-ethoxyethoxy) ethyl acetate, 2-(2-butoxyethoxy) ethyl acetate, 2-ethoxyethyl propionate, 2-ethoxyethyl butyrate, 2-methoxyethyl benzoate, 3-ethoxypropyl acetate, 3-ethoxypropyl propionate, benzyl alcohol, benzyl acetate, benzyl propionate, benzyl butyrate, butyl lactate, ethyl benzoate or isophorone.  Examples describe the spraying of asbestos cement sheets having a mineral oxide pigmented asbestos cement veneer with aqueous dispersions of methyl methacrylate, ethyl acrylate, methacrylic acid copolymers containing (1) 2-butoxyethyl acetate, (4) benzyl alcohol and (5) 2-(2-butoxyethoxy) ethyl acetate; and of a methyl methacrylate-methyl acrylate copolymer containing (3) isophorone.ALSO:Compositions for coating cement products comprise an aqueous dispersion of (1) a polymer of monoethylenically unsaturated monomers and which contains 85 to 100 weight per cent of polymerized methyl methacrylate units and not more than 2 weight per cent of units imparting hydrophilicity to the polymer and (2) an organic solvent boiling in the range 150 DEG  to 255 DEG C.  The polymers may comprise up to 15% of alkyl acrylates, e.g. methyl, ethyl or butyl acrylate, and up to 2% of acrylic, methacrylic or itaconic acid, acrylamide, methacrylamide, b -hydroxyethyl acrylate, b -aminoethyl acrylate, b -hydroxyethyl vinyl ether or b -N,N-dimethylaminoethyl acrylate, and may be prepared by polymerization in aqueous emulsion in the presence of catalysts, e.g. alkali metal and ammonium persulphates and perborates, hydrogen peroxide, tertiary butyl hydroperoxide, cumene hydroperoxide and tertiary butyl perbenzoate.  The solvent may be 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-(2-ethoxyethoxy) ethyl acetate, 2-(2-butoxyethoxy) ethyl acetate, 2-ethoxyethyl propionate, 2-ethoxyethyl butyrate, 2-methoxyethyl propionate, 2-methoxyethyl butyrate, 2-methoxyethyl benzoate, 3-ethoxypropyl acetate, 3-ethoxypropyl propionate, benzyl alcohol, benzyl acetate, benzyl propionate, benzyl butyrate, butyl lactate, ethyl benzoate and isophorone.  Examples describe compositions comprising aqueous dispersions of methyl methacrylate-ethyl acrylatemethacrylic acid copolymers containing (1) 2-butoxyethyl acetate, (4) benzyl alcohol and (5) 2-(2-butoxyethoxy) ethyl acetate; and (3) an aqueous dispersion of a methyl methacrylatemethyl acrylate copolymer containing isophorone.  The compositions may be sprayed on to uncured cement products, e.g. sheets, tiles, shingles, to prevent blocking during curing.