GB1233837A - - Google Patents

Abstract

1,233,837. Ethylene-vinyl acetate interpolymers. GENERAL TIRE & RUBBER CO. 29 Aug., 1969, No. 43222/69. Heading C3P. Ethylene-vinyl acetate interpolymers of high molecular weight and improved tensile strength are produced by (a) polymerizing a monomer mixture of ethylene and vinyl acetate as a disperse phase in an aqueous medium wherein at least one of the components ethylene or vinyl acetate is introduced into the aqueous medium progressively as the polymerization proceeds, and (b) including as a component of the monomer mixture a minor amount, preferably between 1 and 5 parts by weight per 100 parts of ethylene and vinyl acetate of a water-soluble polyoxyethylene compound by progressive addition as the polymerization proceeds, the polyoxyethylene compound having from 2 to 8 terminal -OR groups, wherein R is hydrogen, C 1 to C 10 alkyl or C 6 to C 18 aryl, and from 15 to 100 oxyethylene units. The monomer mixture may contain additionally 0À1-10 parts by weight, for each 100 parts of monomer mixture, of a low molecular weight copolymerizable monomer (other than ethylene and vinyl acetate) having one ethylenic double bond. The interpolymers possess a gel content of at least 25% and an inherent viscosity of at least 1À0 when measured as a 1 % solution in methyl ethyl ketone. Polyoxyethylene compounds particularly mentioned are polyethylene glycol, and the methyl ether or nonyl phenyl ether of polyethylene glycol. Copolymerizable monomer: acrylic acid (preferred) and vinyl chloride, methyl acrylate, ethyl methacrylate, vinylidine chloride, vinyl fluoride, fumaric acid, methacrylic acid, chloroacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, sodium vinyl sulphonate, 2-sulpho ethyl methacrylate, itaconic acid, monoethyl maleate, monoethyl fumarate, dibutyl maleate, acrylonitrile, methacrylonitrile and acrylamide. According to an example, a pressure-tight vessel was charged with (1) an aqueous solution prepared from ammonium persulphate, sodium acetate, hydroxyethyl cellulose and sodium dimethylamyl sulphosuccinate, (2) vinyl acetate and (3) an aqueous solution of iron sulphate, Rochelle salt and sodium formaldehyde sulphoxylate. The vessel was then charged with ethylene at the rate required to achieve and maintain an internal pressure of 150 p.s.i.g. Incremental additions of the following were made as polymerization proceeded: (1) a mixture of vinyl acetate, acrylic acid and the nonyl phenyl ether of polyethylene glycol, containing 20 polyoxyethylene units, (2) an aqueous solution of sodium carbonate and sodium formaldehyde sulphoxylate, and (3) an aqueous solution of ammonium persulphate. Polymerization was halted by the addition of ammonia, urea and sodium phosphate in aqueous solution. The resulting interpolymer contained 83À5% vinyl acetate units, 1À28% acrylic acid units and 15À12% ethylene and glycol ether units.