Compositions d'enduction, en particulier de surfaces métalliques

摘要

A substrate is coated with a solution in an organic solvent of (1) a copolymer of at least one ester of acrylic or methacrylic acid with a C1-4 alkanol and 1/4 to 5% of at least one comonomer containing a polar group, the copolymer containing not more than 1 mole per cent of carboxylic acid or acid salt groups and (2) 1/2 to 20% on the copolymer of a resin-forming polyepoxide condensate (Group IV(a)) and then drying the coating. Curing agents and pigments may also be present. Specified substrates are of paper, wood, textiles, fibre-glass laminates, ceramics, concrete, brick, masonry, leather, plastics, and most especially to primed, phosphated or bare metals such as iron, steel, aluminium or chromium. The coating may be airdried or dried by radiant heat, high-frequency electric currents or infra-red radiation and may be baked at 150 DEG -350 DEG F. to cure. Specifications 518,057 and 579,698 are referred to.ALSO:A composition for coating a substrate comprises a solution in an organic solvent of (1) a copolymer of at least one ester of acrylic or methacrylic acid with a C1-4 alkanol and 1/4 to 5% of at least one comonomer containing a polar group, the copolymer containing not more than 1 mole per cent of units containing COOH or carboxylic acid salt groups and (2) 1/2 to 20% based on the copolymer of a resin-forming polyepoxide condensate. Specified comonomers are 2-ureidoethyl vinyl ether, 2,2-dimethyl-2-ureido-ethyl vinyl ether, glycidyl acrylate and methacrylates, acrylic and methacrylic acids, itaconic acid, acrylamide and methacrylamide, N-alkyl1-4-acrylamide or -methacrylamide, N-methylacrylamidoethyl-N,N1-ethyleneurea, N-(b - (a -acryloxyacetamido) ethyl) -N,N1-ethyleneurea and its a -methacryloxyacetamido homologue. Specified polyepoxides are glycol-bis-exo-dihydrodicyclo-pentadienyl ethers, the condensation products of epichlorohydrin and a polyhydroxy phenol or alcohol or condensation products of phenols with ketones, e.g. the reaction product of epichlorohydrin with bis-(4-hydroxyphenyl)-2,2-propane, with glycerol, ethylene glycol or 4,41-isopropylidene-bis-phenol, and polyepoxides of formula where y is 2, 3 or 4. Specified solvents are toluene, xylenes, 2-ethoxyethylacetate, methyl isobutylketone, methyl ethyl ketone, dioxane, methoxyethanol, ethoxyethanol and ethyl acetate. Specified acrylic esters are the esters of acrylic or methacrylic acid with methanol, ethanol, propanol, n-butanol, sec-butanol and t-butanol copolymers containing at least 50 mole per cent methyl methacrylate are preferred. Curing agents such as acids and anhydrides, e.g. maleic acid or anhydride, or acid salts, e.g. zinc nitrate and chloride or amine or ammonium salts may also be present as may also pigments. The coating may be baked at, e.g. 150 DEG -350 DEG F. Specifications 518,057 and 579,698 are referred to.