DE2364138

1418228 Coagulating styrene polymer latexes SOC ITALIANA RESINE SIR SpA 18 Dec 1973 [22 Dec 1972] 58656/73 Headings C3P and C3G Latexes of copolymers of styrene, acrylonitrile and optionally butadiene are coagulated in a two stage process by maintaining the latex in a first coagulation stage in the presence of a coagulant at a temperature equal to or up to 15‹ C. higher than the distortion temperature of the polymer (as defined by ASTM standard D 648-56 at 264 p.s.i., carried out on injection moulded specimens of dimensions 5 Î ¢ Î “ inch and conditioned for 24 hours at 50‹ C.) for 10- 100 minutes, and bringing the product thereby obtained to boiling or near boiling conditions in a second coagulation phase carried out in at least two stages, the product being maintained in such conditions for 10-100 minutes in each individual stage. The temperature in the second stage is preferably 98-100‹ C. In the examples: (1) and (3), styrene acrylonitrile copolymer latex is coagulated with CaCl 2 ; and (6) and (9); a graft polymer latex of acrylonitrile and styrene on polybutadiene, is also coagulated with CaCl 2 .