Verfahren zur Herstellung von Propylenmischpolymerisaten mit verbesserter Schlagfestigkeit

摘要

Block copolymers are made by a process in which propylene, ethylene and a vinyl aromatic compound are polymerized in such a way that alternately one of the three monomers is present in an amount which is greater than the amount of each of the other two monomers so that polymers are obtained which contain 0.4-20% by weight of ethylene units and 0.4-20% by weight of vinyl aromatic units in addition to propylene units, the polymerization being carried out at temperatures of 0-150 DEG C., at pressures of 1-100 atmospheres and in the presence of catalysts which are mixtures of organometallic compounds of metals of Groups I, II and III and compounds of transition metals of Groups IVa to VIa of the Mendeleef Periodic Table. Vinyl aromatic compounds specified are styrene, vinyl toluenes and chlorostyrenes. The examples describe making block copolymers from propylene, ethylene and styrene, polymerization being carried out with the catalyst mixture either in light naphtha or in finely-divided polypropylene, the catalysts being formed from titanium trichloride and aluminium diethyl chloride. In certain of the described processes polymerization is carried out in the presence of hydrogen, triphenylbutyl phosphonium bromide or triphenylphosphine oxide as a regulator.