Polystyrene moulding materials with improved processing properties - by blending standard or impact polystyrene with low-mol. wt. polystyrene with narrow mol.-wt. distribution

摘要

Thermoplastic moulding materials based on polystyrene (PS) are claimed (I); (I) contain 50-99 wt.% PS or impact PS (A; obtd. by radical polymerisation of styrene, opt. in the presence of a rubber) and 1-50 wt.% PS with mol.wt. distribution (Mw/Mn)= 1.2 or below (B; obtd. by anionic polymerisation); (B) has Mn= 30,000-80,000, and (A) has Mn above that of (B). Pref. (I) contain 60-99 wt.% (A) and 1-40 wt.% (B). - Pref. (A) is produced by bulk or soln. polymerisation, as described, e.g. is US-PS 2694692, and (B) is produced by anionic polymerisation with a Li initiator; (A) and (B) are blended in the melt, pref. in an extruder.