GB994416A - Improvements in or relating to block polymers - Google Patents

Abstract

Block polymers consisting of either two or three sections are made by contacting propylene at a pressure of at least 15 p.s.i.g. with a catalyst system consisting of a subhalide of a Group IVa, Va or VIa metal and an activator therefor selected from hydrides, borohydrides, alkyls, alkylhalides and arylhalides of aluminium, zinc, beryllium, chromium, lithium, magnesium, lithium, sodium, potassium and lead, in an inert hydrocarbon reaction medium, whereby a crystalline polypropylene section is produced which is insoluble in the reaction medium, then contacting the catalyst system with a mixture of propylene and an olefine of the formula CH2= CHR, wherein R is hydrogen, a C2-C6 alkyl radical, a phenyl radical or an aralkyl radical in which the alkyl group contains 2 to 6 carbon atoms, to produce a copolymer section attached to the polypropylene section, and then either separating the resulting block polymer from its reaction medium, or continuing polymerization with one or more olefines other than propylene to produce a third polymer section attached to the previously formed sections, and then separating the resulting block polymer, in either instance the product being a solid, substantially crystalline block polymer which contains only one polypropylene section, and which contains from 80 to 99.8% by weight of units derived from propylene. The examples describe the preparation of block copolymers from propylene and ethylene, with the use of a catalyst composed of titanium trichloride and aluminium diethyl chloride. Specifications 838,996, 886,093, 915,622, 925,571, 927,815, 935,781, 935,782, 935,783, 935,927, 937,557, 937,558, 939,592 and 949,718 are referred to.