| 摘要 |
1,272,171. Aqueous emulsion of ethylene/vinyl acetate copolymers. DENKI KAGAKU KOGYO K.K. 16 March, 1970 [20 March, 1969], No. 12481/70. Heading C3P. A process for preparing aqueous emulsions of ethylene/vinyl acetate copolymers containing 30 to 98% by weight of polymerized ethylene units comprises copolymerizing the respective monomers in aqueous emulsion in the presence of an initiator and an emulsifier composition comprising (A) 5 to 75% by wt. of at least one non-ionic surface active agent having an HLB value of 16-21, (B) 10 to 90% by wt. of at least one anionic surface active agent selected from Na, K or ammonium lauryl sulphate or Na or K dodecyl benzene sulphonate and (C) 4 to 50% by wt. of at least one high molecular weight protective colloid selected from a polyvinyl alcohol having a degree of polymerization of 400-2000 and containing 5-15% by wt. of residual acetic acid groups, or a water-soluble cellulose derivative, the percentages of (A), (B) and (C) being based on the total weight of the emulsifier composition. (A) is preferably a polyoxyethylene lauryl ether, an oxyethyleneoxypropylene block copolymer or a polyoxyethylene nonyl phenyl ether. Other comonomers which may be polymerized with the ethylene and vinyl acetate, are vinyl chloride, vinylidene chloride, maleic acid, acrylic acid, methacrylic acid, an acrylic or methacrylic acid ester, acrylamide or vinyl butyrate. Examples describe the copolymerization of ethylene and vinyl acetate in the presence of various combinations of the preferred surfactants and protective colloids, with an initiator of ammonium persulphate and in an ethylene atmosphere. The polymerization is preferably carried out under a pressure of 70 to 1000 atmospheres. The produced emulsions find use as adhesives.
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