GB944241A - Coating compositions - Google Patents

Abstract

Coating compositions contain a catalytic amount of an acidic material, 5 to 67 parts by weight of a butanol-soluble condensation product of formaldehyde with an amino compound, e.g. urea, melamine or benzoguanamine, and 100 parts by weight of an amide-containing copolymeric material which includes 3 to 15% by weight of acrylamide, or methacrylamide or the N-methylol derivatives thereof, or mixtures of any of these with one another, "b"% by weight of a C1-C10 aliphatic acrylate, and "c"% by weight of methyl, ethyl or butyl methacrylate, or vinyl toluene, or mixtures of any of these with one another or with styrene, the value of "b" being from 0 to 87 and the value of "c", when representing a single monomer, being: (1) 35 to 97 for methyl methacrylate (2) 40 to 97 for ethyl methacrylate (3) 65 to 97 for butyl methacrylate (4) 10 to 35 for vinyl toluene, and, when representing a mixture of two monomers, conforming to the equation "C"=nq+ p(1-n), where n is a number ranging from 0 to 1, nq and p(1-n) represent weight percentages of different monomers and p and q have values for the different monomers which are the same as those given above, with the additional value of 15 to 40 for styrene, and when the copolymeric material comprises more than one copolymer, each copolymer contains from 3 to 15% of said unsaturated amide or amides. Also present in the copolymers may be minor proportions of other monomers, e.g. hexyl and lauryl methacrylates, alpha-methylstyrene, isopropyl styrene, acrylonitrile and dibutyl maleate. Acidic materials specified are p-toluene sulphonic acid, aluminium chloride, boron trifluoride, phosphoric acid, perchloric acid, maleic acid, n-butyl sulphamic acid, methane sulphonic acid, tetrachlorophthalic acid and its monobutyl ester, monobutyl dichloromaleate, and amine salts of sulphonic acids. The compositions are dissolved in solvents such as xylene-butanol, butanol, methyl, butyl and amyl acetates, acetone, methyl ethyl and methyl isobutyl ketones, cyclohexanone, toluene, xylene and mineral spirits. Also present in the compositions may be an alkyl resin or a pigment, e.g. titanium dioxide. After application the composition is cured by heating to 120 to 150 DEG C. The Specification describes also the preparation of copolymers of the above mentioned type by heating to reflux a mixture of monomers in xylene-butanol and thereafter gradually adding thereto a second mixture consisting of xylene, monomers, benzoyl peroxide and tert.-butyl hydroperoxide, the whole amount of the amide monomer being present in the first mixture.ALSO:Steel panels are coated with compositions which comprise a solution in an organic solvent of a mixture of a catalytic amount of an acidic material, e.g. p-toluene sulphonic acid, 5 to 67 parts by weight of a butanol-soluble condensation product of formaldehyde with an aminocompound, e.g. urea, melamine or benzoguanamine, and 100 parts by weight of an amidecontaining copolymeric material which includes 3 to 15% by weight of acrylamide, or methacrylamide or the N-methylol derivatives thereof, or mixtures of any of these with one another, 0 to 87% by weight of a C1-C10 aliphatic acrylate, and "C"% by weight of methyl, ethyl or butyl methacrylate, vinyl toluene or mixtures of these with one another or with styrene, the value of "C", when representing a single monomer, being 1) 35 to 97 for methyl methacrylate 2) 40 to 97 for ethyl methacrylate 3) 65 to 97 for butyl methacrylate 4) 10 to 35 for vinyl toluene, and, when representing a mixture of two monomers, conforming to the equation "C" = nq+p(1-n) where n is a number ranging from 0 to 1, nq and p(1-n) represent weight percentages of different monomers and p and q have values for the different monomers which are the same as those given above, with the additional value of 15 to 40 for styrene, and when the copolymeric material comprises more than one copolymer, each copolymer contains from 3 to 15% of said unsaturated amide or amides. Also present in the copolymers may be minor proportions of other monomers, e.g. hexyl and lauryl methacrylates, alphamethylstyrene, isopropylstyrene, acrylonitrile and di butyl maleate. The preferred acidic material is p-toluene sulphonic acid and the preferred organic solvent is a xylene-butanol mixture. Also present in the compositions may be a pigment, e.g titanium dioxide. After application the composition is cured by heating to 120-150 DEG C.