VERFAHREN ZUR VERHINDERUNG DER ANREICHERUNG EINES POLYMERISATS AUF DEN INNEREN OBERFLAECHEN EINES POLYMERISATIONSGEFAESSES WAEHREND DER POLYMERISATION IN WAESSRIGER DISPERSION

1477270 Preventing polymer scale formation during polymerization CONTINENTAL OIL CO 16 Oct 1975 [29 Oct 1974] 42505/75 Heading C3P Polymer build-up on the interior surfaces of a polymerization vessel during the aqueous dispersion polymerization of a water-insoluble monoethylenic monomer which is liquid under the polymerization conditions, is inhibited by adding benzotriazole and/or tolyltriazole and/or 2 - (21- hydroxy - 51 - methylphenyl)benzotriazole to the dispersion prior to polymerization. Build-up may be further inhibited by additionally including (1) an alkylated copolymer of an N-vinyl lactam of the formula wherein n is an integer of 1 to 3 and R and R 1 are independently, H, CH 3 or C 2 H 5 ; and an at least C 2 alpha olefin, and/or (2) an alkali- or alkaline earth metal salt of an aminocarboxylic acid of formula (R) n -N-(A-COOH) 3-n wherein R is -CH 2 CH 2 OH or -CH 2 CH 2 CH 2 OH, A is C 1 _ 3 alkylene and n is zero, 1 or 2, or of the formula wherein Z is C 1-4 alkylene; X is zero, 1, 2, 3 or 4; Y and Y1 are independently H, -CH 2 COOH or hydroxyalkyl and Y11 is H or -CH 2 COOH. The preferred amino carboxylic acid salt is the tetra sodium salt of E.D.T.A. The examples relate to vinyl chloride polymerization.