Preparing ethylene polymers using Ziegler catalyst comprising cyclodienyl compound of zirconium

摘要

The invention relates to a method for preparing polymers of ethylene and propylene, or of copolymers of ethylene and alpha olefins such as propylene 1-butene and 1-hexene or alpha omega dienes such as alpha omega octadiene, respectively, by polymerization within a temperature range from -80 DEG to 150 DEG C. in the presence of a halogen free Ziegler type catalyst system consisting of a cyclopentadienyl compound containing a transition metal and of an aluminum alkyl compound, whereby the polymerization is made in the presence of catalyst system consisting of the following components: (1) a compound containing a transition metal and having the general formula (cyclopentadienyl)nMeYn, in which n is an integer from 1 to 4, Me is a transition metal, preferably zirconium, and Y being selected from the group of hydrogen, a C1-C5 alkyl group or C1-C5 metal alkyl group or of a compound of the following general formula in which R is a C1-C5 alkyl group or C1-C5 metalloalkyl group, and (2) an aluminum containing compound of the alumoxan type having the general formula (R-Al-O)m, in which m is an integer of 1 to 20 and R a C1-C5 alkyl group. Preferably the polymerization is effected in the presence of a catalyst system consisting of bis(cyclopentadienyl)zirconium methyl and an alumoxan of the above mentioned formula in which R is methyl group and m being above 2 and preferably above 5. Preferred copolymers of ethylene are obtained with 0.1 to 10% by weight of 1-butene, 1-hexene and alpha omega dienes such as the octadiene, as well as with propylene.