Studies on the low pressure polymerization of ethylene using catalysts containing lithium alkyls

Abstract

AbstractThe low and atmospheric pressure polymerizations of ethylene using catalysts prepared from n‐butyl lithium or isoamyl lithium and titanium tetrachloride were studied. The efficiency of the catalyst depended on the molecular ratio of the alkyl lithium to titanium tetrachloride. Optimum molecular ratio for the n‐butyl lithium–titanium tetrachloride was found to be between 2.15–2.47 with a sharp drop between 2.15–1.49; for the isoamyl lithium the optimum was between 2.5–4.3. Within the examined interval (of atmospheric pressure to a pressure of 60–70 lb./sq. in.) higher pressure caused an increase in the yield of polyethylene. No pronounced effect in polymerization was found in the temperature interval of −10–55°. The catalyst is stable for a few days if kept refrigerated. Petroleum ether, b.p. 40–80°, was the best solvent both for the preparation of the catalyst and for the polymerization. Ligroin, toluene, and especially ether interfered with the polymerization. The polyethylenes obtained melted between 125–135°.