PROCEDIMENTO PER PREPARARE OMOPOLIMERI E COPOLIMERI DI ALFA-MONOOLEFI NE E SISTEMA CATALIZZATORE CONTENENTE COMPOSTI FENOLICI NON IMPEDITI PER ESSO

A catalyst and a process for the preparation of homopolymers and copolymers of alpha monoolefins by means of a catalyst system comprising (1) a titanium halide of the formula TiCl3 m AlCl3 where m is a number from 0 to 0.5, (2) a coordination complexing agent, the use of which is optional, and (3) an appropriate conventional aluminum- alkyl, the titanium halide (1) and the complexing agent (2), if used, having been milled together before use, wherein the catalyst system employed contains, as a further component (4), a sterically unhindered phenolic compound i.e. a phenol in which any groups ortho to the OH group, are selected from H, -CH3, -OCH3 and -CH2H5.