GB1066605A - Polyethylene - Google Patents

Abstract

Polyethylene is made by polymerizing ethylene in an inert liquid diluent in the presence of a catalyst consisting of TiCl4 and a trialkyl-aluminium wherein the molar ratio of the tri-alkylaluminium to TiCl4 is at least 1.0, at a temperature from 70 DEG C. to just below the temperature at which the polyethylene would become soluble in the reaction mixture, and controlling the molecular weight of the product by adding hydrogen to the reaction mixture. The polyethylene product has the following properties, M.P. above 127 DEG C., density from 0.95 to 0.97 gm./c.c., has an intrinsic viscosity in the range from 0.5 to 3.0 deciliters per gm., and is soluble in 1-chloronaphthalene at 160 DEG C. forming a solution at 0.5% by weight concentration of polymer which is either filterable or non-filterable through a U.F. grade sintered glass filter having from 0.9 to 1.4 micron pores at a pressure difference of one atmosphere, and further when filterable the filtered solution gives a distorted light Zimm plot. The polyethylene is also thermoplastic and the X-ray diffraction pattern shows high crystallinity, the standard Melt Index is from 0.1 to 10, and the infra-red absorption spectrum shows not more than one side chain per 200 carbon atoms and no detectable proportion of trans-carbon-to-carbon double bonds. The polymerization and recovery is carried out using conventional "low-pressure" techniques.