单茂钛/MAO体系催化乙烯/丙烯共聚合研究Ⅰ.乙烯/丙烯共聚物的合成及聚合反应规律研究

采用合成的催化剂五甲基环戊二烯基三烯丙氧基钛 Cp Ti(OAllyl) 3]与改性甲基铝氧烷 (mMAO)组成新型催化体系进行乙烯 /丙烯共聚合 ,考察了助催化剂 (mMAO)中TMA含量、气体配比、聚合温度、助催化剂和主催化剂浓度等因素对共聚合活性及产物分子量的影响 ,研究其变化规律 .结果表明 ,Cp Ti(OAllyl) 3/mMAO催化体系中钛的价态分布为Ti(Ⅳ )时对共聚合更为有利 ,制得了乙烯 /丙烯无规共聚物弹性体

ETHYLENE/PROPYLENE COPOLYMERIZATION WITH HALF-TITANOCENE/MAO CATALYSTⅠ . SYNTHESIS OF ETHYLENE/PROPYLENE COPOLYMER

A novel half\|titanocene compound,( η \+5\|pentamethylcyclopentadienyl) titanium triallyloxide (Cp\+*Ti(OCH\-2 CH CH\-2)\-3), and modified methylalumiloxane (mMAO) were synthesized and employed in the study on ethylene\|propylene copolymerization.The influences of the amount of residual TMA in MAO,ethylene\|propylene feeding molar ratio,polymerization temperature and the concentrations of catalyst and mMAO on activity of ethylene\|propylene copolymerization,molecular weight of copolymer have been discussed in detail.It was found that the catalytic activity increased with the decreasing of the amount of residual TMA in MAO,such as from 22.3% to 14.8% TMA content in MAO,resulting in the Ti(Ⅳ) species content from 40.8% up to 88.8%,which indicated that the Ti(Ⅳ) species is favorable for the ethylene\|propylene copolymerization.The activity also increased with the decreasing of ethylene molar ratio in feeding comonomer,it perhaps related to the chain structure and physical state of copolymer.The catalytic activity was affected obviously by the polymeric temperature,but it was not as sensitive in higher ethylene\|propylene feeding molar ratio(E/P=70∶30) as that in lower E/P feeding ratio(E/P=10∶90),this performance suggested that higher temperature was more suitable for ethylene polymerization than for propylene polymerization.The varying ranges of Al/Ti=140～230mol/mol and \=1.0×10 -3 ～1.2×10 -3 mol/L were the optimum conditions for ethylene\|propylene copolymerization.Subsequently,high molecular weight random ethylene\|propylene copolymer elastomers,most of those can be soluble in hexane,were obtained by the catalyst.