PROCESS FOR THE PREPARATION OF ETHYLENE POLYMER OR COPOLYMER

摘要

1281829 Polymerization of ethylene MITSUI PETROCHEMICAL INDUSTRIES Ltd 3 Dec 1969 [3 Dec 1968] 59135/69 Heading C3P Process for preparing polymers of ethylene comprises (i) polymerizing ethylene, optionally with a minor amount of one or more comonomers, in the liquid phase at a temperature of 160-300‹ C., and at a pressure of 30-200 kg./cm.2 gauge, in a polymerization solvent which is a chain or cyclic pentane, hexane or heptane, in the presence of a Ziegler catalyst obtained by mixing (a) a halogen compound of Ti or V supported on a carrier, and (b) an organoaluminium compound or dialkyl zinc; (ii) maintaining the polymer concentration in the polymerization zone not above 20% by weight, and controlling the polymerization temperature by circulating a gaseous mixture containing an inert gas; (iii) subjecting the resultant liquid phase reaction product containing molten polymer to a lower pressure than the polymerization pressure so as to vaporize the solvent; and (iv) recovering the residual ethylene polymer. Catalyst component (a) may be prepared by heating the Ti or V halogen compound above its melting point, e.g. to 40- 150‹ C. for 10 minutes to 5 hours, in the presence of the carrier, e.g. an oxide, hydroxide, hydrous oxide, sulphate, carbonate, phosphate or halogen compound of magnesium or manganese (II). In the examples: (1) ethylene is polymerized, alone or with propylene as comonomer, in hexane, in the presence of H 2 as molecular weight modifier, using as catalyst a mixture of TiCl 4 supported a magnesium hydroxide or magnesium oxide, and triethylaluminium.