Process for the preparation of homopolymers and copolymers of propylene which have particularly good applicational properties

摘要

The invention relates to a process for the preparation of homopolymers and copolymers of propylene by means of a Ziegler-Natta catalyst system comprising (1) a certain titanium halide (titanium trichloride/aluminium chloride cocrystallizate), (2) a certain oxygen compound (ester), (3) an alkylaluminium compound and (4) a certain phenolic substance, which is characterised in that, in a separate process step, the polymer is homogenised and extruded without other interim treatment together with small amounts of (A) a complex compound of formula [Mg1-xAlx(OH)2+x.m'H2O]n, where x = 0.1 to 0.5, m' = 0 to 2, and n' = 3 to 12, (B) pentaerythrityl tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)]propionate, (C) tetrakis (2,4-di-t-butylphenyl)-4,4-diphenyl diphosphonite, and (D) calcium stearate, with melting of the polymer, giving polymers which have particularly good applicational properties.