Mitsubishi Chemical Industries Limited

Yasuhiro Nishihara

Nobuaki Goko

Yumito Uehara

Toshizo Abe

Yoshinori Suga

Masayoshi Hasuo

Masatoshi Suzuki

Seiho Sakamoto

Yukimasa Matuda

Ryokichi Takashima

Hidetoshi Yamamoto

Hidetoshi Saruwatari

A method for producing an .alpha.-olefin block copolymer, which comprises polymerizing propylene alone or together with a small amount of other .alpha.-olefin in the presence of a catalyst comprising a titanium-containing solid catalyst component and an organoaluminum compound, and then polymerizing the resulting propylene polymer with an .alpha.-olefin other than propylene, alone or together with propylene in a gas phase without deactivating the catalyst, characterized in that the gas phase polymerization is conducted in the presence of a siloxane or a polysiloxane in an amount of from 1.times.10.sup.-6 to 0.1 by weight ratio relative to the weight of said propylene polymer.

Method for producing an .alpha.-olefin block copolymer

The present invention relates to a process for producing a polypropylene-ethylene block copolymer by a continuous multi-stage polymerization comprising a first stage in which polypropylene is polymerized in a first polymerization vessel in the presence of a propylene polymerization catalyst, and a second stage in which propylene and ethylene are copolymerized in a second polymerization vessel, wherein the polypropylene slurry discharged from the first polymerization vessel is supplied to a concentrator to separate said slurry into a concentrated polypropylene slurry and a supernatant liquid, the concentrated polypropylene slurry is then introduced through an upper part of a hydraulic sedimentation classifier to be contacted with a countercurrent of the upward flowing of the supernatant fluid introduced through a lower part of said classifier to obtain hydraulically sedimented polypropylene, and non-hydraulically sedimented polypropylene; the thus obtained hydraulically-sedimented polypropylene is then supplied to the second polymerization vessel or to a further propylene polymerization vessel and the non-hydraulically sedimented polypropylene is then recycled from the classifier to the first polymerization vessel. The present process produces a propylene-ethylene block copolymer having excellent characteristics of cold shortness and high impact strength.

Process for continuously producing propylene-ethylene block copolymer

A process for producing a polyolefin characterized by polymerizing an olefin in the presence of a catalytic system composed of solid titanium trichloride, an organic aluminum compound, an aromatic hydrocarbon and a monocarboxylic acid ester having an olefinic double bond or an aromatic ring in the molecule thereof.

Process for producing polyolefins

A solid titanium trichloride, produced by precipitation from a homogeneous solution or mixture with an ether, is treated by prepolymerization with propylene at a partial pressure of less than 1 kg/cm.sup.2. The pretreated titanium trichloride containing a propylene polymer is then admixed with an organoaluminum compound and the admixture is used as a catalyst in the polymerization of propylene.

Preparation of propylene polymer-containing solid titanium trichloride

A process for polymerizing an olefin comprises effecting said polymerization in contact with a catalyst of a combination of a first solid component prepared by treating a mixture of (a) a titanium tetrahalide, (b) a vanadyl alcoholate and (c) a vanadyl trihalide, with an organoaluminum compound, and a second component of an organoaluminum compound.

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Kurashiki, Japan

Yasuhiro Nishihara