High grade ethylene@] copolymers - obtd. by bulk polymerisation in multi-zone tube reactions with external countercurrent water codling under special temp. conditions

摘要

Prodn. of ethylene (co)polymers with improved properties and high conversion includes high pressure bulk polymerisation, in multizone tubular reactors at 150-250 MPa and 393-603 K in the presence of O2 and other free radical producing cpds., molecular wt. regulators and opt. modifiers or comonomers with flow rates of 4-20 m/sec. A preheater is connected to at least the first reaction zone (zone 1) and a countercurrent of hot water is passed through a heating mantle along the reactor, leaving the reactor at the inlet to zone 1. The novelty is that, in zone 1, between the monomer temp. immediately before the point of addn. of peroxide (T1) and the reactor temp. (T2) at a distance of 300-320 L/D from the measuring pt. for T1, there is a temp. difference of 8-30 K above the temp. of the hot water leaving the reactor (T3), which is set within the range 480-498 K in the outer mandle at the pt. where T1 is measured. USE/ADVANTAGE - The invention provides a modification of the prior art polymerisation process which enables the prodn. of high quality (i.e. film grade) PE in high yield over long periods of operatio