Chisso Corporation

Atsuyoshi Shimizu

Nobutoshi Komori

Takeshi Suzuki

Hiroshi Shimizu

Takehiko Takahashi

Kazumasa Shibata

Takehiro Umeno

Takashi Koizumi

Masamitsu Iwasaki

Devolatilization of sticky polyolefin powder and deactivation of catalyst residue can be carried out efficiently and sufficiently without the need for accompanying facilities commonly used in the treatment of powdery products in an apparatus comprising (a) a horizontal cylindrical body, (b) a stirrer provided with one revolving shaft and a plurality of specified stirring blades (c) an inlet pipe for introducing untreated polyolefin power and heating gas, (d) a variable barrage for controlling the holding amount of polyolefin powder insides of said horizontal cylindrical body, (e) an outlet way for discharging after-treated polyolefin powder and gas, (f) inlet pipes for heating gas having a pipe for feeding an after-treating agent, and (g) indirect heating mean.

Apparatus for after-treating polyolefin powder

A process for producing ethylene-propylene block copolymer by the use of a catalyst employed for producing isotactic polypropylene is provided. This process is characterized in that a gas phase polymerization of propylene is substantially carried out in the presence of the catalyst obtained by combining a titanium trichloride composition with an average particle size of 10.about.100 .mu. and an organic aluminum to form the propylene polymer segment with a specific surface area more than 0.015 m.sup.2 /g at a yield of more than 3,000 g per 1 g of the titanium trichloride composition in the first step, and then a gas phase polymerization of a mixture of polypropylene and ethylene is successively carried out in the second step to form the copolymer segment with a copolymerization ratio of propylene:ethylene being 5.about.80 weight %:95.about.20 weight %, wherein the polymerized amount of the second step is 10-40% of total polymerized amount and wherein normal hexane extraction ratio (75.degree. C., 1 hour) of the ethylene-propylene block copolymer powders obtained is 1.about.10 weight %. The process of the present invention is one having an extremely high productivity industrially, and the modified polypropylene obtained has a superior low-temperature-impact strength and brittle temperature.

Process for producing modified polypropylene

Growing community of inventors

Ichiharashi, Japan

Atsuyoshi Shimizu