GB1087623A - Thermosetting coating compositions - Google Patents

Abstract

Thermosetting coating compositions comprise a mixture dissolved in an organic solvent of (A) 55 to 95% by weight of a thermoplastic copolymer obtained by copolymerization of a mixture consisting of (a) 10 to 50% by weight of a versatic acid 911 vinyl ester, (b) 0 to 6% by weight of a copolymerizable a ,b -ethylenically unsaturated mono-, di- and/or poly-carboxylic acid or a partial ester of such a di- or poly-carboxylic acid derived from a C1-C8 alkanol, (c) 20 to 50% by weight of methyl methacrylate, (d) 20 to 50% by weight of an ester of acrylic acid and a C4-C18 alkanol, (e) 5 to 20% by weight of a hydroxyalkyl or hydroxyaralkyl ester of an a ,b -ethylenically unsaturated carboxylic acid; and (B) 5 to 45% by weight of a resin-forming condensate of an aldehyde and urea, N,N1 - ethyleneurea, dicyanodiamide or an aminotriazine, alkylated with cyclohexanol or a C1-C6 alkanol. Specified components (b) are acrylic, methacrylic, ethacrylic, phenylacrylic, maleic, fumaric, itaconic, citraconic and crotonic acids and, where existent, the partial alkyl esters of such acids. Component (e) may be derived from the same acids as used in component (b) and preferably contains at least one primary or secondary hydroxyl group. The aminoplast precondensate is preferably derived from formaldehyde although other aldhydes such as acetaldehyde, crotonaldehyde and acrolein are also suitable. In examples an etherified melamine-formaldehyde product is used. Suitable solvents include aromatic hydrocarbons, aliphatic and cyloaliphatic alcohols and ketones, aliphatic esters and ethers, dioxan, dimethyl formamide, dimethyl acetamide, acetonitrile and nitroalkanes. The composition may also include pigments, extenders and hardening catalysts. Pigments include chrome yellow, Prussian blue, Brunswick green, titanium pigments possibly extended with alkaline earth metal sulphates, titanate salts, zinc compounds, antimony oxide, and organic pigments including calcium and barium lakes and azo dyes. Suitable hardening catalysts include inorganic acids and their ammonium salts and organic acids and their amine salts and certain esters. The copolymers can be prepared by polymerizing the respective monomers in a solvent using a catalyst such as benzoyl peroxide, di-t.-butyl peroxide, t.-butyl hydroperoxide, cumene hydroperoxide or azoisobutyro-nitrile and, if desired, a chain transfer agent, e.g. butyl or lauryl mercaptan or thioglycollic acid.ALSO:Thermosetting compositions suitable for coating vehicle bodies, paper, textiles, leather, wood, synthetic materials, ceramics, bricks, concrete and metals comprise a mixture dissolved in an organic solvent of (A) 55 to 95% of a thermoplastic copolymer of (i) a versatic acid 911 vinyl ester (ii) methyl methacrylate (iii) an ester of acrylic acid with a C4-C18 alkanol (iv) a hydroxyalkyl or hydroxyaralkyl ester of an a , b -ethylenically unsaturated carboxylic acid and, optionally, (v) an a , b -ethylenically unsaturated mono-, di- and/or polycarboxylic acid or a partial ester of such a di- or poly-carboxylic acid with a C1-C8 alkanol; and (B) 5 to 45% by weight of a resin-forming condensate of an aldehyde with urea, N,N\sv-ethyleneurea, dicyanodiamide or an aminotriazine (e.g. melamine), alkylated with cyclohexanol or a C1-C6 alkanol. Suitable solvents include aromatic hydrocarbons, aliphatic and cycloaliphatic alcohols and ketones, aliphatic esters and ethers, dioxan, dimethyl formamide, dimethyl acetamide, acetonitrile and nitroalkanes. The composition may also include pigments, extenders and hardening catalysts. Pigments include chrome yellow, Prussian blue, Brunswick green, titanium pigments possibly extended with alkaline earth metal sulphates, titanate salts, zinc compounds, antimony oxide, and organic pigments including calcium and barium lakes and azo dyes. Suitable hardening catalysts include inorganic acids and their ammonium salts, and organic acids and their amine salts and certain esters. The compositions may be applied in various ways, e.g. by coating, spraying, dipping or roller-coating. The coatings can be dried at room temperature or up to 100 DEG C, and hardened at 80-230 DEG C. In Examples the coatings are applied to iron sheets, deep-drawn metal sheets and phosphated metal sheets.