Urethane acrylate compounds and compositions

The present invention relates to a process for the polymerization of olefins. The method used is a transition metal Group of the Periodic Table ⅣB e.g. zirconium compound, alumoxane and trimethyl aluminum in conjunction with at least a catalyst formed of a hydrocarbon group other than an n-alkyl aluminoxane on the aluminum atom, a olefin polymerization. In this method, even if reducing the amount of aluminoxane formed by the high prices of trimethylaluminum olefin polymerization may be performed at an excellent polymerization activity, and can be obtained relatively high molecular weight polymers.