Process for the preparation of a poly-1-olefin

Use of shock waves instead of a stirrer for mixing the reactants gives a particularly uniform, spherical Ziegler catalyst. This highly active catalyst based on a dialkyl magnesium compound can be used in the polymerisation of alpha-olefins to give spherical polymers. A further advantage of the novel catalyst is the high catalyst activity, so that only very small amounts of the catalyst are necessary for the polymerisation. The residual titanium and/or zirconium content in the polymers prepared in accordance with the invention is less than 10 ppm. Its good hydrogen activity means that the catalyst is particularly suitable in two-step processes for the preparation of polymers having a broad, bimodal molecular weight distribution. Replacement of sulphur-containing electron donors, such as diethyl sulphite, by alcohols, such as ethanol, results in less odour nuisance and an expanded range of applications of the polymer. This spherical shape of the particles and the consequent very good flow properties of the polymers and copolymers mean considerable simplifications and advantages during handling, drying and processing.