Continuous bulk polymn. process - for moulding compsns., made from styrene plus other monomers of different reactivity

摘要

Uniform thermoplastic moulding compsns. are continuously produced from random copolymers of intrinsic viscosity 0.1-2 dl/g (DMF at 25 degrees C) which are stable at 90-130 degrees C and comprise (A) 22-96 mole % styrene and/or alpha-methylstyrene; (B) 0-78 mole % >=1 olefin unsatd. nitrile-contg. monomer and (C) 0-50 mole % >=1 other monoolefinically unsatd. monomer by (i) copolymerising at 60-150 degrees C in presence of an initiator of half-life =1/10 dwell time but greater than incorporation time, and in a reactor-reservoir with continuous circulation and ideal mixing for 10-240 mins. (mixing time 5-120 sec), 100 wt. pts. of a monomer mixt. comprising 4-99.6 mole % (A); 0-96 mole % (B) and 0-80 mole % (C), with back mixing until conversion is 10-60 mole %; then (ii) adding 0.5-100 wt. pts. of a mixt. of 0-100 mole % each of (A), (B) and/or (C) plus 0.01-0.5 wt.% initiator having the same properties under the polymsn. conditions of the third stage as the first initiator in stage (i); then (iii) copolymerising at 100-250 degrees C for 10-480 mins. (incorporation time 0.1-4 mins.) in a completely-filled mixer, which is self cleaning and fitted with mobile mixing elements which scrape the walls and each other with back-mixing, until the residual monomer content is 10-50 mole % (on total monomers), then degassing the monomer-contg. copolymer with a vacuum or inert gas purge until residual monomer content is 0.5 wt.%. Process allows uniform, transparent, and stable polymers to be made from monomers of widely differing reactivities.