Mitsubishi Chemical Corporation

Japan Polychem Corporation

Fuminao Watanabe

Eiji Tanaka

Glen H Ko

Kenji Mitsutani

Kiyoshi Yukawa

Fumihiko Shimizu

Jun Hosoi

A stable continuous production of a propylene-based block copolymer can proceed for a long time without causing accumulation of particles having a small diameter by a process having the following steps: (1) polymerizing an &agr;-olefin containing liquid propylene as a main component in the presence of hydrogen and a stereoregular polymerization catalyst in one or more polymerization reactors to obtain a polymer slurry; (2) feeding the polymer slurry to a copolymerization reactor; and (3) copolymerizing propylene and an &agr;-olefin other than propylene substantially in a gaseous phase in the presence of the stereoregular polymerization catalyst, the polymer slurry and a deactivating compound in the copolymerization reactor to obtain a propylene-block copolymer powder. The polymer slurry, discharged from one of said one or more polymerization reactors and is classified using a classification system to obtain a) a classified polymer slurry containing a large amount of particles having a small particle diameter and b) a classified polymer slurry containing a large amount of particles having a large particle diameter. A main part of the classified polymer slurry containing a large amount of particles having a small particle diameter is recycled to a final polymerization reactor of the one or more polymerization reactors.

Continuous production method of propylene-based block copolymer

A concentration distribution of a rubber component in block copolymer particles is computed based on the operating conditions of a polymerization apparatus, a growth model equation of polymer particles on a solid catalyst component, and a residence time distribution of the particles in each of a homopolymerization stage and a copolymerization stage, and the gel content of the block copolymer is estimated based on the computation. The gel content of a propylene block copolymer can thereby be estimated precisely.

Method of estimating gel content of propylene block copolymer

The present invention provides a propylene block copolymer comprising polymer particles whose rubber-like component contents are 50% by weight or more, in an amount less than 1.0% by weight of the whole polymer particles finally discharged from a polymerization system.

Propylene block copolymer

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Okayama, Japan

Fuminao Watanabe