Graft copolymer prodn. used for electrical equipment - by emulsion polymerisation of monomer mixt. and crosslinked particulate elastomer graft using hydroperoxide and partly neutralised ascorbic acid

摘要

Prodn. of graft copolymers (I) is carried out by emulsion polymerisation at pH over 7 of (a) 80-10 (wt.)% monomer mixt. of (a1) 50-99 pts. styrene, alpha-methylstyrene, ring-substd. styrene and/or methyl methacrylate and (a2) 1-50 pts. (meth)acrylonitrile, methyl methacrylate, n-butyl acrylate, t-butyl (meth)acrylate, maleic anhydride and/or N-alkyl- or N-aryl-substd. maleimide and (b) 20-90% (partly) crosslinked, particulate elastomer graft substrate with Tg less than 0 deg.C. and an average particle dia. (d50) of 0.05-2 microns. A free radical initiator system of an organic hydroperoxide and ascorbic acid (II) is used. The aq. (II) soln. used in the original charge and added is adjusted to pH greater than 3.5. USE/ADVANTAGE - The pptn. of (I) particulate unsuitable as modifiers before graft polymerisation is complete is almost entirely suppressed and hence the total yield of effective (I) powder is increased considerably. (I) can be used as or in thermoplastic moulding compsns., which are suitable e.g. for injection moulding to housings (of domestic appliances, e.g. juice pressers, coffee machines and mixers), cover plates for the building trade and car pts.. Their very good electrical properties make (I) suitable for electrical equipment, e.g. moulded plu