GB804537A - Process for the preparation of unsaturated polyester resin mixtures - Google Patents

Abstract

Unsaturated polyester mixtures which can be polymerized in presence of air to give nontacky films suitable for use as lacquers or casting resins are obtained by incorporating a partially epoxidized unsaturated oil into a polyester formed from one or more unsaturated dicarboxylic acids and one or more polyglycols and combining the resulting modified unsaturated polyester with a monomeric polymerizable vinyl compound. Unsaturated polyesters are obtained in known manner by esterification with glycols of a ,b -unsaturated dicarboxylic acids, e.g. fumaric, maleic acids or their anhydrides. Glycols specified are ethylene, diethylene triethylene glycols, 1,2-, 1,3-propane diols and 1,3-, 1,4-butane diols. Unsaturated oils which may be epoxidized are soya, linseed, hemp seed, castor, perilla and wood oils and synthetic oils, e.g. tall oils, fatty acid esterified with polyhydric alcohols. The partially epoxidized oil should have an iodine number of 100-150 after epoxidization. An inhibitor, e.g. hydroquinone, tertiary butyl pyrocatechol may be dissolved in the vinyl compound, e.g. styrene, to prevent premature copolymerization. Organic hydroperoxides or peroxides may be used as catalysts together with accelerators, e.g. cobalt naphthenate or dimethyl aniline. Saturated mono or dicarboxylic acids and monohydric alcohols may be used in addition to the unsaturated acids and glycols. The epoxidized oil may be added when the unsaturated polyester ingredients have been reacted to the required acid number. In examples: (1) linseed oil of acid No. 180 is epoxidized by reaction with hydrogen peroxide and formic acid to give a product having an epoxy content of 2.6 per cent. Maleic anhydride, phthalic anhydride and 1,2-propane diol are melted and heated to 180-250 DEG C. under carbon dioxide until a product having an acid No. of 120 is obtained and the product is then reacted with the epoxidized linseed oil. The product is cooled and mixed with styrene and hydroquinone and then with a 10 per cent solution of cobalt naphthenate in styrene. The mixture shortly before use is mixed with a 40 per cent methyl ethyl ketonehydroperoxide solution or a 50 per cent cyclohexanone-hydroperoxide solution in dimethyl phthalate and sprayed on to a surface. In examples: (2) p-tert.-butyl benzoic acid, (3) a hydrogenated resin acid, (4) an unsaturated C16-C18 fatty alcohol are used as constituents of the polyester reactants. In Example (5) the epoxidized oil is obtained from fish oil.