CONTROL OF MOLECULAR WEIGHT OF POLYBUTADIENE PREPARED BY VAPOR PHASE POLYMERIZATION IN THE PRESENCE OF RARE EARTH CATALYST

摘要

PROBLEM TO BE SOLVED: To control the molecular weight and/or molecular weight distribution of a vapor- phase-polymerized high cis-1,4-polybutadiene by regulating at least one factor selected from among a polymerization temperature, the partial pressure of butadiene, the concentration of a promoter, the selection of a promoter, the residence time of a catalyst, etc., in the presence of a rare earth metal containing catalyst.;SOLUTION: The molecular weight and/or molecular weight distribution of a high-cis-1,4- polybutadiene formed from 1,3-butadiene in the presence of a rare-earth-metal-containing catalyst in a vapor-phase process is controlled by regulating at least one of the following conditions: (a) a polymerization temperature (as this rises, the molecular weight decreases, and the molecular weight distribution widens), (b) the partial pressure of butadiene (as this pressure increases, the molecular weight increases, and the molecular weight distribution narrows), (c) the concentration of a promoter (as this decreases, the molecular weight increases, and the molecular weight distribution narrows), (d) the selection of a promoter (the molecular weight changes according to a combination of a catalyst with the promoter), and (e) the residence time of a catalyst (as the average residence time increases, the molecular weight increases, and the molecular weight distribution narrows).;COPYRIGHT: (C)2000,JPO