PROCESS FOR PRODUCING RUBBER-MODIFIED PLASTICS

摘要

1338789 Graft polymerization process SUMITOMO CHEMICAL CO Ltd 23 June 1971 [24 June 1970] 29466/71 Heading C3G A rubber-modified polymer is produced by a process comprising (i) bulk polymerizing a solution of a synthetic rubber in a mixture of styrene and acrylonitrile by heating the solution in the absence of an initiator until from 3À5 to 15% by weight of the monomers has been polymerized, (ii) adding a chain transfer agent to the reaction mixture and continuing bulk polymerization until from 20 to 40% of the original monomers has been polymerized and (iii) suspension polymerizing the pre-polymer produced in the presence of lauroyl peroxide and a suspending agent. Additional monomers, e.g. (a) alpha-methylstyrene, (b) dimethylstyrene or (c) chlorostyrene may be included in the acrylonitrile-styrene solution. In the examples, an acrylonitrile/styrene solution, optionally containing said monomer (a) or (b), of polybutadiene is polymerized using t-dodecylmercaptan as chain transfer agent and an acrylonitrile/styrene solution containing styrene-butadiene rubber is polymerized using a t-dodecylmercaptan / t - hexadecylmercaptan / t - tetradecylmercaptan mixture. An additional amount of acrylonitrile is added in the suspension polymerization stage in Example 6.