APERFEICOAMENTO EM PROCESSO PARA PRODUZIR COMPOSICOES DE REVESTIMENTO

摘要

A copolymer of (A) at least 50% of one or more of methyl or ethyl methacrylate, acrylonitrile, methacrylonitrile, styrene or o-, m- or p-vinyl-toluene, and (B) 0.5-10% of one or more of acids of formula where R is H or CH3 and A is a C1- 3 alkylene group, and optionally (C) one or more other monoethylenically unsaturated monomers, e.g. a -methylstyrene, vinyl acetate or chloride, vinylidene chloride, esters of acrylic acid with a saturated hydrocarbon group having 1-18 C atoms and esters of methacrylic acid with a saturated hydrocarbon group having 3-18 C atoms; the copolymer contains not more than 10% of hydrophilic monomers, e.g. acryl-, methacryl-, N-methylolacryl-, or N-methylolmethacryl-amides or b - hydroxyethyl vinyl ether. Other acids, e.g. methacrylic, acrylic and itaconic may also be comonomers. The above (B) acids may be a -methacryloxy-acetic, -propionic or -butyric; b -methacryloxy-propionic or -butyric; a -acyloxy-acetic, -propionic or -butyric; b -acryloxy-propionic; g -acryloxybutyric; or g -methacryloxy-butyric. The copolymer may also contain as monomer an internal plasticizer, e.g. ethyl or butyl acrylate, ethylene, isobutylene, esters of acrylic acid with monohydric alcohols having 1-18 or more C atoms or esters of methacrylic acid with alcohols having 3-18 C atoms. The copolymer may be made by free-radical polymerization in an organic solvent or by granular, emulsion or suspension polymerization. A catalyst may be used, e.g. an organic peroxide or an azo compound such as a ,a 1-azodiisobutyronitrile. In an example a mixture of monomers and benzoyl peroxide was polymerized in toluol. A lacquer may comprise an organic solvent solution of the copolymer and may contain up to 50% or more of an external plasticizer, e.g. benzyl butyl or dibutyl phthalate, 2-ethylhexyl benzyl phthalate, dicyclohexyl phthalate, triphenylphosphate, diallyl or dibenzyl phthalate, butyl cyclohexyl phthalate, mixed benzoic acid and fatty oil acid esters of pentaerythritol, poly(propylene adipate) dibenzoate, diethylene glycol dibenzoate, tetrabutyl-thiodisuccinate, butyl phthalyl butyl glycolate, acetyl-tributyl citrate, dibenzyl sebacate, tricresyl phosphate, toluene ethyl sulphonamide, the di-2-ethylhexyl ester of hexamethylene di-phthalate and di-(methylcyclohexyl)phthalate. The solvent may be toluene, xylenes, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, amyl alcohol, 2-ethoxy-ethyl acetate, butyl lactate; amyl or methyl or ethyl acetates; denatured ethanol, isopropanol, diacetone alcohol, cyclohexanol, ethylene dichloride, di-isobutyl ketone, cyclohexanone, 2-butoxyethanol, furfuryl, petroleum naphtha of b.p. 87-145 DEG C., cyclohexane, hexane and aromatic hydrocarbon mixtures. Mixtures of solvents may be used. The lacquer may also contain up to 100% pigment and/or other filmforming material. The pigment may be TiO2, C black, Fe blues, phthalocyanine blues and greens; metal, e.g. Fe oxides, hydroxides, sulphides, sulphates, silicates and chromates, e.g. of Pb or Zn; organic maroons, Al flake, bronze powders, pearl essence and fillers such as talc, barytes, china clay and diatomaceous earth. The lacquer concentrate, e.g. 5-75% solids, may be diluted with more organic solvent to form a coating composition, e.g. 5-30% solids. The lacquer may contain other film-forming materials, e.g. cellulose nitrate, other cellulose esters, alkyd resins and polyether diepoxide.ALSO:A substrate is coated by brushing, dipping, roller-coating, or air or steam spraying with an organic solvent solution of a copolymer of (A) at least 50% of one or more of methyl or ethyl methacrylate, acrylonitrile, methacrylonitrile, styrene or vinyltoluene, and (B) 0,5-10% of one or more acids of formula where R is H or CH3 and A is a C1-3 alkylene group, and the coating is dried. The substrate may be bare or primed metal, e.g. steel, wood, ceramics, plastics, or glass. The coating solution may be pre-heated.