Continuous 3-step bulk copolymerisation of styrene - comprising continuous copolymerisation, monomer mixt. addn. and copolymerisation in flooded mixer

摘要

Continuous bulk polymerisation of monomers having different reactivities, i.e. (A) 22-92 mol. % styrene and/or alpha-Me styrene, (B) 0.78 mol% =1 nitrile gp.-contg. mono-olefinically unsatd. monomer and (C) 0-50 mol. % =1 mono-olefinically unsatd. monomer other than (A) or (B), where A + B + C = 100 mol. %, takes place in homogeneous liquid phase of 1-20 bar, by (I) 100 pts. wt./time unit of monomer mixt. of (A1) 4-99.6 mol. % (A), (B1) 0.-96 mol. % (B) and (C1) 0-80 mol. % (C), copolymerised to 10-60 mol. % conversion to copolymer abc at 60-150 degrees C, in presence of an initiator having half-life period at polymerisation temp. 1/10 of av. dwelling time and mixing time, in a tank reactor allowing continuous flow and ideal mixing, at av. periods of dwell 10-240 min. and mixing times 5-120 secs. (II) 0.5-100 pts. wt./time unit of monomer mixt. of (A2) 0-100 mol. % (A), (B2) 0-100 mol. % (B) and (C2) 0-100 mol. % (C), where sum of mol. % of A1B1C1 and of A2B2C2 is 100, is mixed with 0.01-0.5 wt. %, w.r.t. sum of residual monomers of A1B1C1 and of monomers A2B2C2, of an initiator having half-life period of polymerisation temp. of step (III) 1/10 dwelling period and mixing time of polymerisation batch. (III), continuous copolymerisation takes place, in bulk, homogeneous phase, in a completely flooded, self-cleaning polymerisation mixer with moving mixer devices stripping walls and one another, at 100-250 degrees C, with av. period of dwell 10-480 min. and mixing times 0.1-4 min., up to residual monomer content 10-50 mol. %, w.r.t. total monomers. Residual monomer-contg. copolymer ABC is purified from residual monomers, down to 0.5 wt. % w.r.t. copolymer, by setting up a vacuum or by blowing in inert gas. Products are used as thermoplastic moulding compsns. for injection moulded, ddep drawn and compressed articles, e.g. dishes, armatures, household goods, internal fitting for cars and boats, optical and electronic devices, and foils and containers for packing foods. Copolymers have av. mol. wt. 104 to 106, intrinsic viscosity 0.1-2 dl/g (in DMF at 25 degrees C), are transparent, glass-clear, and have heat shape stability at 90-130 degrees C. Notch impact strength according to DIN 7741 is 2-10 cm kp/cm2, melt index, at 200 degrees C and 21.6 kp loading, is 2.8-20 g/101.