PREPARATION OF POLY 1- OLEFIN

Bead-form polymers can be obtained in the polymerisation of alpha-olefins by using a highly active, spherical Ziegler catalyst based on a dialkylmagnesium compound. A further advantage of the novel catalyst is the high catalyst activity, meaning that only very small amounts of the catalyst are necessary for the polymerisation. The residual content of titanium and/or zirconium in the polymers prepared according to the invention is less than 10 ppm. Its very good hydrogen sensitivity means that the catalyst is particularly suitable in two-step processes for the preparation of polymers having a broad, bimodal molecular weight distribution. The replacement of sulphur-containing electron donors, such as diethyl sulphite, by alcohols, such as ethanol, results in lower odour nuisance and a broadened range of possible applications of the polymer. The spherical shape of the particles and the consequent very good flow properties of the polymers and copolymers mean considerable simplification and advantages during handling, drying and processing.