EFFECTS OF DIETHYL ALUMINUM-CHLORIDE (DEAC) ADDITION TO THE CATALYSTSPREPARED BY REDUCTION OF TICL4 WITH ETMGCL ON ETHYLENE-PROPYLENE COPOLYMERIZATION

TiCl3/2.5MgCl2(0.5MgEt2)/THF catalyst (R) was prepared by the reductio n of TiCl4 with EtMgCl. The effect of diethyl aluminum chloride (DEAC) addition on the catalytic activity in ethylene-propylene copolymeriza tion was investigated. It was suggested from FT-i.r. that the catalyst R formed similar bimetallic (Ti-Mg-THF) complexes to the TiCl3(AA)/3M gCl2/THF catalyst (T3ME) of our previous report [7]. An ESR study prov ided evidence that the Ti3+ species in the catalyst R was of the multi nuclear type, instead of an isolated type of T3ME, and it changed from a tetrahedral to an octahedral structure with addition of DEAC. The a ctivities of R catalysts in copolymerization were more or less in the same order of magnitude with each other due to the multinuclear nature of the Ti3+ species, and the response to propylene comonomer decrease d with addition of DEAC. The polydispersity of comonomer over R cataly sts was in the range of 6-10, being much broader than that over the T3 ME catalyst system. It might be due to the heterogeneity of the titani um(III) structure; tetrahedral as well as octahedral in R, instead of only octahedral in T3ME.