Sumitomo Chemical Company, Limited

Sumitomo Rubber Industries Limited

Kizuku Wakatsuki

Keisaku Yamamoto

Masahiro Kakugo

Hayato Saba

Kazuki Wakamatsu

Yoshiharu Fukui

Tadashi Hikasa

Kiyoyuki Sugimori

Kazuo Baba

Tadayuki Ohmae

Akinobu Shiga

Akio Imai

Junichi Kimura

Mitsuji Tsuji

Seiichiro Ima

Yuichi Saito

Kentaro Mashita

Katsunari Inagaki

Noboru Yamaguchi

Toshio Kawakita

Tadaaki Nishiyama

Junpei Kojima

Shigeo Tanaka

Toru Fukumoto

Tomohisa Fukao

Jiro Sakai

Shuji Imaoka

Toshimi Sato

Tadayuki Okada

Junpei Kozima

Hideaki Nishio

A rubber composition obtained by kneading a mixture comprising 100 parts by weight of a solution polymerized diene rubber, 5-100 parts by weight of silica, 1-15 parts by weight of a silane coupling agent, and 1-20 parts by weight of an organic silicon compound having a number average molecular weight of about 100-10,000, and maintaining the temperature during the kneading at 200.degree. C. or less. The composition is excellent in wear resistance and productivity, has lower rolling resistance and is useful, for example, for automobile tires.

Rubber composition

Provided is a rubber composition obtainable by kneading a mixture at a maximum temperature between about 120.degree. to about 170.degree. C. The mixture includes:

A process for producing ethylene-.alpha.-olefin copolymer rubbers which comprises mixing a vanadium compound-containing solution and an alcohol-containing solution with stirring for 10-600 seconds to obtain a mixed solution, immediately feeding the mixed solution into a polymerization vessel containing an organoaluminum compound, and copolymerizing ethylene and an .alpha.-olefin, or ethylene, an .alpha.-olefin and a non-conjugated diene compound in the polymerization vessel. According to this process, the activity of polymerization catalyst can be maintained at a high level, no by-product of the reaction of the vanadium compound and the alcohol is deposited as precipitate in the apparatus and no such additional operations as bubbling is necessary.

Process for producing ethylene-alpha-olefin copolymer rubber

A rubber composition for tire treads comprising a rubber component consisting essentially of (A) 20 to 100% by weight of a solution-polymerized styrene-butadiene copolymer rubber having a Mooney viscosity ML.sub.1+4 of 30 to 200 at 100.degree. C. prepared by copolymerization of styrene, butadiene and a polyvinyl aromatic compound followed by coupling with a trifunctional or tetrafunctional coupling agent, and (B) 0 to 80% by weight of at least one rubber selected from the group consisting of an emulsion-polymerized styrene-butadiene rubber, a butadiene rubber, natural rubber and a synthetic polyisoprene rubber; and (C) 50 to 250 parts by weight of a carbon black having an iodine adsorption number of not less than 60 mg/g and an oil absorption of not less than 110 ml/100 g per 100 parts by weight of said rubber component; the tan .delta. peak temperature Tg of the cured product of said rubber composition being from -40.degree. to +5.degree. C. The tread rubber composition can be processed without causing bagging with a good dispersibility of carbon black and provides tires having a low rolling resistance and a high grip characteristic.

Rubber composition for tire treads

An elastomeric butadiene copolymer prepared by a process which comprises copolymerizing butadiene, a polyvinyl aromatic compound and optionally styrene in a hydrocarbon solvent in the presence of an organolithium polymerization initiator and subjecting the resulting copolymer having lithium at the polymer end or ends to a coupling reaction with a trifunctional or tetrafunctional coupling agent, said butadiene copolymer satisfying the following conditions: (a) the content of styrene is at most 50% by weight, (b) the content of vinyl bonds in the butadiene portion is from 10 to 90% by weight, (c) the molecular weight distribution curve obtained by a high performance liquid chromatography has at least three peaks, and 5 to 60% by weight of all the polymer chains have a molecular weight which is at least 5 times the molecular weight in terms of standard polystyrene corresponding to the peak appearing on the lowest molecular weight side of the high performance liquid chromatogram, and (d) the Mooney viscosity (ML.sub.1+4, 100.degree. C.) is from 30 to 200. The butadiene copolymer has an improved processability with excellent resilience, wet grip property, abrasion resistance and mechanical properties, and is suitable for tire use.

Butadiene copolymer and process for preparing same

A method for purifying an ethylene-.alpha.-olefin olefin having at least 3 carbon atoms, or ethylene with an .alpha.-olefin having at least 3 carbon atoms and a nonconjugated diene compound, in a hydrocarbon solvent in the presence of a catalyst comprising a vanadium compound, an organoaluminum compound, and a halogenated ester compound, the method including a step of mixing and stirring the polymerization reaction mixture obtained by the polymerization reaction in an aqueous alkaline solution in such an amount as to give an aqueous phase having a pH of not lower than 10.0 after mixing and stirring, is disclosed. A method for purifying an ethylene-.alpha.-olefin copolymer is also disclosed, including a step of an oxidation treatment of the polymerization reaction mixture in an aqueous alkaline solution in such an amount as to give an aqueous phase having a pH of not lower than 10.0 after the oxidation treatment.

Method for purifying ethylene-.alpha.-olefin copolymer

An inert hydrocarbon solvent-soluble catalyst for polymerization of olefinic hydrocarbons and a process for producing an olefinic polymer using the same are disclosed, the catalyst being composed of (A) a reaction product obtained by reacting (a) at least one vanadium compound represented by formula:

Catalyst for olefinic hydrocarbon polymerization and process and

Catalyst for olefinic hydrocarbon polymerization and process for

High-Strength polypropylene fiber is obtained from polypropylene having incorporated therein from 0.05 to 10,000 ppm by weight of a vinylcycloalkane polymer. The disclosed fiber polypropylene has an intrinsic viscosity of from 0.5 to 2.5 dl/g as measured in a tetralin solution at 135.degree. C. and a ratio of weight average molecular weight to number average molecular weight of not more than 3.5/1.

High-strength polypropylene fiber

A resinous composition suitable for powder coating on metals on which a heat resistant coating layer is formed contains (A) modified polypropylene in which unsaturated carboxylic acid or anhydride is grafted on crystalline propylene/.alpha.-olefin copolymer, (B) ethylene polymer, (C) metal oxide or hydroxide and (D) polymers of C.sub.6 or more vinyl cycloalkane and the composition contains 0.001-1.0% by weight of the vinyl cycloalkane unit.

Resinous composition for powder coating

There is disclosed resin composition comprising 1 to 99% by weight of a polymer A and 1 to 99% by weight of a polymer B, the polymer A and B having refractive indexes which permit satisfaction of the relation:

Resin composition

A process for producing a 4-methylpentene-1 copolymer comprising copolymerizing 4-methylpentene-1 with other .alpha.-olefin in a hydrocarbon solvent in the presence of a Ziegler-Natta catalyst and a resin composition containing the 4-methylpentene-1 copolymer are disclosed. The copolymerization comprises a first stage in which (A) a homopolymer or random copolymer of 4-methylpentene-1 having an .alpha.-olefin content of not more than 3 mol % and an intrinsic viscosity of at least 2.5 dl/g is prepared and a second stage in which (B) a random copolymer having an .alpha.-olefin content higher than that of the polymer (A) and no higher than 9 mol % and an intrinsic viscosity of at least 2.5 dl/g is prepared, and the produced copolymer insoluble in the solvent is separated to recover a 4-methylpentene-1 copolymer containing from 5 to 80% by weight of the polymer (A). The process produces a solvent-insoluble copolymer in an increased yield without impairing transparency of the copolymer.

Process for producing 4-methylpentene-1 copolymer and resin composition

A crystalline polypropylene sheet is described, characterized by containing a polymer of a vinylcycloalkane having at least 6 carbon atoms in an amount of 0.05 wt ppm to 1 wt % (calculated as a vinylcycloalkane unit). This sheet is excellent in stiffness and transparency and is suitable for use in the production of various articles such as containers and trays.

Polypropylene sheet

A process for producing a propylene copolymer having improved transparency and rigidity, which comprises carrying out (A) the polymerization of a vinyl cycloalkane having at least 6 carbon atoms and (B) the polymerization of propylene either alone or with ethylene in a multiplicity of steps in the presence of a catalyst system composed of a titanium compound and an organoaluminum compound. The content of the vinyl cycloalkane unit in the resulting copolymer is 0.05 to 10,000 weight ppm.

Process for producing propylene copolymer

A crystalline polybutene-1 composition containing from 1.times.10.sup.-6 to 10% byweight of a vinylcycloalkane unit having a melting point of 180.degree. C. or higher in terms of its homopolymer, is disclosed. The composition has a markedly improved rate of crystal conversion of polybutene-1.

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Chiba, Japan

Kizuku Wakatsuki