Process for producing polyethylene

Claim 1

In a process for polymerizing ethylene at a high temperature and a high pressure using two autoclave reactors connected in a series through a heat exchanger, by using the preceding autoclave reactor partitioned into a first and second reaction zone, feeding the major part of the starting ethylene into the first reaction zone of the preceding autoclave reactor, feeding the remaining starting ethylene into the succeeding autoclave reactor, polymerizing the ethylene fed into the first reaction zone of the preceding autoclave reactor in the presence of a polymerization initiator under a pressure of 1,000-2,800 kg/cm 2 at a temperature of 130°-200° C., introducing the reaction mixture thus obtained into the second reaction zone of the preceding autoclave reactor, polymerizing the reaction mixture in the presence of a polymerization initiator at a temperature of 210°-280° C., cooling the reaction mixture discharged from the second reaction zone of the preceding autoclave reactor by means of the heat exchanger to a temperature which is not lower than 120° C. and is 20° C. or more lower than the reaction temperature in the second reaction zone of the preceding autoclave reactor, feeding the cooled mixture into the succeeding autoclave reactor and polymerizing it there in the presence of a polymerizing initiator under a pressure of 1,000-2,800 kg/cm 2 , the improvement which comprises using a reactor having one reaction zone as the succeeding autoclave reactor and polymerizing the mixture fed into the succeeding autoclave reactor at a temperature of 210°-280° C.