High activity Ziegler–Natta catalysts for the preparation of ethylene copolymers

摘要: High activity ethylene polymerization catalysts have been prepared by the interaction of ethylmagnesium chloride in tetrahydrofuran with high surface area silica, followed reaction excess titanium tetrachloride heptane. The were tested ethylene—hexene copolymerization reactions presence AlEt3 at 80°C. For comparison purposes, properties a similar catalyst without silica also evaluated. Preparative conditions identified which provide that possess reactivity towards 1-hexane. and amount magnesium used preparation strongly affect catalysts. Generally, showed much higher sensitivity to 1-hexene (effective ratio r1 = 25–60) while exhibited an value 125. Fractionation copolymer series boiling solvents all exhibit wide distribution active centers respect ratios, values varying from 5–7 ca. 200. width center depends on composition—it is narrowest for widest intermediate Ti : Mg ratios.