High impact polystyrene made by anionic polymerisation - with subsequent structuring of the polymer with a per cpd. or redox system

摘要

High impact polystyrene is made by (1) polymerising styrene in the presence of (a) a polymer of a conjugated diene or a random copolymer, graft polymer or block copolymer of a conjugated diene with styrene, or a mixt. of these as reinforcing agent; (b) an anionic catalyst comprising organic derivs. of alkali metals, or adducts of these; and (c) a reaction medium consisting of inert aliphatic, cycloaliphatic or aromatic hydrocarbons or mixts. of these, and (2) after the polymerisation, structuring the polymer using a per cpd. or an oxidn.-redn. system. Pref. reinforcing agent is a butadiene-styrene-butadiene block copolymer with 3-12 arms in which each arm contains 1-2 polybutadiene blocks and 1-2 polystyrene blocks and the total content of bound butadiene is 30-80 wt. After the polymerisation and before the structuring process, additional polymeric reinforcing agent can be added to the mixt. to give a polymer compsn. contg. 4-30 wt.% bound diolefin. The structuring process is pref. carried out using an organic per cpd. such as isopropylbenzenehydroperoxide, tert.butylhydroperoxide, tert.butylperoxide, dicumylperoxide, tert.butylperbenzoateperoxide, isopropylcyclohexylbenzenehydroperoxide, as oxidising agent and SO2 as reducing agent.