Study On Polymerization Of CIS-1, 4-Polyisoprene With Titanium Catalyst

Titanium catalyst is commonly used for preparation of polyisoprene. Polyisoprenewith high cis-l,4 content was obtained by a twofold system composed of complexTiCl₄ and Al(i-Bu)3.The solution of polyisoprene is compounded in hydrogenatedgasoline.The effect of monomer ratios and another conditions of polymerization werediscussed in detail.Polyisoprene having cis-l,4 content of 96ï¼…,[η] of 2.18 dl·g^-1 andgel content of 5ï¼…was obtained by TiCl₄-Al(i-Bu)₃ system under the followingconditions: [Ip]/[Oil]=1/4(volume ratio), n(Ti)/n(Ip)=2×10^-3, n(Al)/n(Ti)=1, 50℃polymerized for 4hr.High cis-1, 4 content Polyisoprene was also obtained successfully by a ternarycatalytic system TiCla-Al(i-Bu)3-Diphenylether.The effect of complex orders andcomponent dosage were studied.This catalytic could improve cis-l,4 content ofpolyisoprene meanwhile polymer with cis-l,4 content of 98.6ï¼…was obtained. Gelcontent of polyisoprene prepared by catalytic system (A1-DPE)-Ti and AI-(DPE-Ti)was reduced.Polyisoprene with cis-content of 96ï¼…was obtained by catalytic systemTiCl₄-AlCl₃-Al(i-Bu)₃. The effect of Al/Ti mole ratio, catalyst concentration andtemperature on polymerization were discussed. Cis-1, 4 polyisoprene could be obtainedunder n(Al)/n(Ti)=1～6.Catalytic efficiency is 158gPIp/gTi under the followingconditions: h(Ti)/n(Ip)=1×10^-3, n(Al)/n(Ti)=4, 80℃polymerized for 4hr. High catalyticactivity was obtained when the catalyst system was prepared at -60℃and gel contentof polyisoprene could be decreased.