| 摘要 |
1,214,362. Coating. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ. 14 July, 1969 [15 July, 1968], No. 33600/68. Heading B2E. [Also in Division C3] Resinous polymers, particularly suitable as a binder in stoving enamels in combination with formaldehyde-condensation products, are prepared by partially hydrolyzing in an acid medium copolymers obtained by copolymerization of: (a) one or more vinyl esters of saturated aliphatic monocarboxylic acids having the carboxyl group attached to a primary or secondary carbon atom, (b) one or more vinyl esters of saturated aliphatic manocanboxylic acids having the carboxyl group attached to a tertiary or quaternary carbon atom, and (c) one or more alpha, beta-ethylenically unsaturated carboxylic acids. Weight ratios of vinyl esters (a) to vinyl esters (b) in the copolymer may range between 15:85 and 85:15, and the alpha, beta-ethylenically unsaturated acid may amount to 1-20%, based on the total weight of the copolymer. The partial hydrolysis is conducted to obtain a resinous copolymer having a hydroxy content between 50 and 250 mg. eq./100g. and an acid number 'between 7 and 20 mg. KOH/g. Vinyl esters (a): vinyl acetate, propionate, butyrate, palmitate and stearate. Vinyl esters (b): vinyl esters of saturated aliphatic C 5 -C 20 monocarboxylic acids exemplified by pivalic acid; 1,1,3,3-tetramethylbutanecarboxylic acid; 1,2-dimethyl-1-isopropyl-propane carboxylic acid and 1,1,4-trimethyl-pentanecarboxylic acid. Alpha, betaethylenically unsaturated carboxylic acids: acrylic, methacrylic, maleic, fumaric, itaconic and aconitic acids. An example is directed to the preparation of a copolymer of vinyl acetate, mixed vinyl esters of saturated C 9 -C 11 monocarboxylic acids branched at the alpha carbon atom and acrylic acid. The copolymer produced is partially hydrolyzed in emulsion in water in the presence of para-toluene sulphonic acid. (The water contained a small amount of sodium alkylbenzenesulphonate as emulsifying agent.) Pastes comprising a ca.50% solution of the hydrolyzed copolymer in xylene/butanol, titanium dioxide (pigment) and further xylene and butanol, were worked up into stoving enamels by mixing them with melamineformaldehyde resin, adding xylene to attain spraying viscosity. The paints are sprayed on to steel panels and stoved. The stoved coatings could be polished without damaging the smooth appearance. |
