Process for the preparation of catalyst compositions for olefin polymerisation, catalyst compositions prepared by this process and application of the said compositions

摘要

This process is of the type in which, in a first stage, an element of groups IVA to VIA of the Periodic Classification is reacted with an organometallic compound of an element of groups I to III. In a second stage an organometallic compound of an element of groups I to III, which is identical or otherwise to the preceding one is added to the product of this reaction. According to the invention an olefin is reacted with the products present during one of these stages, between them or after the second stage.