Mitsui Chemicals, Inc.

Toshihiro Okano

Yoshiaki Kikuchi

Ryoichi Yamamoto

Satoru Ohtani

Mitsunori Ichimura

Shotaro Matsuda

A method of multistage gas phase polymerization is provided comprising performing polymerization of a feed gas mixture at least containing ethylene gas, an &agr;-olefin gas and hydrogen gas in an upstream fluid bed reactor to thereby produce a polymer powder, recovering the thus-produced polymer powder and performing further polymerization of the polymer powder in a downstream fluid bed reactor, the downstream fluid bed reactor being continuously connected to the upstream fluid bed reactor so that the polymer powder recovered from the upstream fluid bed reactor is introduced into the downstream fluid bed reactor, which method comprises the steps of: recovering polymer powder from the upstream fluid bed reactor, treating the recovered polymer powder so as to lower the content of &agr;-olefin gas and hydrogen gas therein by contacting the polymer powder with a stream of gas comprising ethylene or an inert gas, and introducing the treated polymer powder into the downstream fluid bed reactor. By this method, &agr;-olefin gas and hydrogen gas which inhibit the polymerization reaction in the downstream fluid bed reactor and which render regulation of desired polymer product properties difficult are removed from the polymer product prior to the downstream fluid bed reactor.

Method of multistage gas phase polymerization, apparatus therefor and device for reducing entrainment of subcomponents in polymer powder in apparatus for multistage gas phase polymerization

A method for vapor phase polymerization comprises blowing a gaseous monomer from a bottom of a fluidized bed reactor through a distributor plate into the reactor by means of a blower while feeding a solid catalyst into the reactor to thereby form a fluidized bed in the reactor and conducting a vapor phase polymerization to produce a polymer or copolymer, wherein the blower has a slide or rotational slide part between its discharge side as a high pressure side and its suction side as a low pressure side in a blower body casing, said slide or rotational slide part being provided with a noncontacted gas leakproof seal part at a clearance ranging from 0.7 to 2.5 mm.

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Ichihara, Japan

Toshihiro Okano