Mitsui Petrochemical Industries, Ltd.

Kenichi Tominari

Norio Kashiwa

Masayuki Sakai

Masayoshi Kurisu

Takeshi Muranaka

Hiroshi Inoue

Junichi Yoshitake

Shiro Honma

Hiroaki Kitani

Kunio Furutachi

Shigeki Nagamatsu

Yoshihiro Tsukamoto

Yuzi Miura

An injection-molding polyethylene composition consisting essentially of ultrahigh-molecular-weight polyethylene having a molecular weight of at least about 1,650,000 and low-molecular-weight to high-molecular-weight polyethylene having a molecular weight of, for example, about 1500 to about 360,000. This composition is produced by a multistep polymerization process comprising a step of producing the ultrahigh-molecular-weight polyethylene and a step of producing the low-molecular-weight or high-molecular-weight polyethylene.

Injection-molding polyolefin composition

In a flash-drying process which comprises flashing a solvent solution of a polymer or copolymer maintained at an elevated temperature and pressure into a flashing zone maintained at a lower pressure than the pressure of the solvent solution through a means for releasing said elevated pressure, thereby evaporating and separating the solvent from the solvent solution, the improvement wherein an inert stripping agent is fed into a flow of the solvent solution at any point between said pressure-releasing means and said flashing zone.

Flash-drying process for a solvent solution of a polymer or copolymer

A branched alpha-olefinic polymer composition having excellent melt flowability, good moldability and excellent melt tension and comprising at least two branched alpha-olefinic polymers each composed of (A) recurring units derived from a branched alpha-olefin containing 5 to 10 carbon atoms and having a branch at the 3-position or a position of a higher number and (B) recurring units derived from a linear alpha-olefin containing 2 to 20 carbon atoms; and a process for producing this polymer composition by a multiplicity of polymerization steps using a catalyst formed from (A) a highly stereoregular titanium catalyst component comprising magnesium, titanium, halogen and an electron donor as essential ingredient, (B) an organoaluminum compound and (C) an electron donor.

Branched alpha-olefin polymer composition and process for its production

Ethylene/C.sub.4 -C.sub.20 alpha-olefin copolymers are disclosed which have new characteristics in regard to composition distribution, degree of branching, randomness and crystallinity by DSC melting points. These copolymers have excellent transparency, impact strength, tear strength, blocking resistance, environmental stress cracking resistance, heat resistance and low-temperature heat sealability in a well-balanced combination when they have a density of at least 0.90. When their density is less than 0.90, these copolymers have particularly excellent transparency, impact strength and low-temperature heat sealability, and by incorporating them in various thermoplastic resins, they serve as an excellent modifier for improved impact strength and low-temperature heat sealability.

Linear ethylene copolymer

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Ichihara, Japan

Kenichi Tominari