| 摘要 |
1513867 Neutralized copolymers PPG INDUSTRIES Inc 15 May 1975 [16 May 1974 5 Aug 1974] 1351/78 Divided out of 1513866 Heading C3P Water-based coating compositions for use as internal coatings for metallic beverage containers comprise:- (a) an ammonia- or aminepartially neutralized copolymer containing (i) 5-25 wt.% of acrylamide or methacrylamide in the form of units of formula in which R<1> is H or methyl, and R is H or butyl, at least 50% of R being butyl, (ii) 3-25 wt.% of acidic units derived from acrylic acid, (iii) 3-75 wt.% of hard monomer units derived from styrene, and (iv) 5-75 wt.% of flexible monomer units derived from ethyl acrylate, said copolymer having been produced by polymerization in the absence of a mercaptan, and being neutralized with ammonia or amine sufficient to solubilize the copolymer but which provides not more than 0-764 milliequivalents of salt per gram of resin solids; and (b) a liquid medium comprising water or a mixture of at least 60% water with a water-soluble or watermiscible organic solvent. The units of Formula I may be produced by after-treatment of a (meth) - acrylamide-containing copolymer, but preferably are obtained directly by copolymerization of an appropriate monomer. In Examples, copolymers obtained by copolymerization of N- (butoxymethyl)acrylamide, acrylic acid, styrene and ethyl acrylate are neutralized with dimethyl ethanolamine and formulated into coating compositions of which the liquid medium is a mixture of water, butanol, isopropanol, toluene and ethyl- or butyl-Cellosolve (Trade Mark). |
