GB824340A - Improvements in composition and process for preparing same - Google Patents

Abstract

A synthetic resin coating composition comprises a mixture of (1) 50 to 10% of a water-soluble, potentially thermosetting, aminoplast resin forming compound, and (2) 50 to 90% of a water-soluble ammonium salt of a copolymer derived essentially from (a) 50 to 5% of one or more alpha, beta-ethylenically unsaturated carboxylic acids, and (b) 50 to 95% of one or more alkyl esters of alpha, beta-ethylenically unsaturated monocarboxylic acids, and (c) optionally, up to 25% of a polymerizable monomer containing a CH2=C< group which is water-soluble to an extent less than 10% by weight of room temperature. The thermosetting aminoplast composition may be the reaction product of aldehydes such as formaldehyde, acetaldehyde, crotonic aldehyde, acrolein, benzaldehyde, furfuraldehyde, paraldehyde, trioxymethylene or paraformaldehyde with compounds such as urea, ethylene urea, dicyandiamide, melamine or formo-, benzo- or acetoguanamine and the products may be etherified e.g. the dimethyl ether of trimethylol melamine. The unsaturated carboxylic acid (a) may be a monocarboxylic acid such as acrylic, beta-benzoyl acrylic, methacrylic, cinnamic or crotonic acids or a polycarboxylic acid such as maleic, fumaric, itaconic, citraconic, mesaconic or aconitic acids or halogenated acids such as halogenated maleic, e.g. chloromaleic acid. The corresponding anhydrides may be used in place of the acids in the copolymerization. The alkyl ester (b) may be the methyl, ethyl, propyl, butyl, octyl, decyl or lauryl esters of acrylic acid or may be ethyl, butyl, heptyl or decyl methacrylate or propyl, butyl or nonyl crotonate. The comonomer (c) may be styrene or methyl, ethyl, propyl or butyl styrenes; dimethyl styrenes; vinyl naphthalene; acrylonitrile; methacrylonitrile; halogeno ring or side chain styrenes, e.g. alphachlorostyrene, o-, m- or p-chlorostyrene, 2,3-, 2,4- or 2,5-dichlorostyrene or alkyl side chain styrenes, e.g. alpha-methyl or alpha-ethyl styrene. The copolymers are rendered water-soluble by conversion to the ammonium salts by reacting with aqueous ammonia. The coating compositions may be applied in aqueous solution and may comprise a catalyst such as hydrochloric, sulphuric or nitric acids or further ingredients such as rutile titanium dioxide or the monomethyl ether of ethylene glycol. In the examples copolymers of alkyl arylates with acrylic acid and terpolymers derived from these monomers and also styrene or acrylonitrile are made by copolymerization in dioxane using cumene hydroperoxide as catalyst. A modifier such as butyl mercaptan may be present, the reactants may be added incrementally and the copolymers obtained are reacted with aqueous ammonia.