Bridgestone Corporation

Japan Synthetic Rubber Co., Ltd.

Ube Industries, Inc.

Tatsuro Hamada

Yoichi Ozawa

Tatsuo Fujimaki

Noboru Oshima

Mitsuhiko Sakakibara

Iwakazu Hattori

Fumio Tsutsumi

Noboru Shimada

Hiromi Fukuoka

Akihiko Morikawa

Hideki Komatsu

Toshihiro Tadaki

Hiroshi Mouri

Eiji Yamanaka

Masayuki Ohashi

Peyman Pakdel

Yoshihisa Fujinaga

Seiichiro Iwafune

Hideaki Yokoyama

Masanori Aoyama

Yoshiyuki Morimoto

Koji Yamauchi

Yoshitaka Yamakawa

Yoshishige Chikatsu

Koichi Nagakura

Fuji Yamanaka

Kyouyuu Yasuda

Koji Ishiguchi

Toshiaki Fukuhori

A rubber composition includes a rubber component and particulates of a crystalline syndiotactic-1,2-polybutadiene resin dispersed therein. The particulates have an average particle diameter of 1 to 500 .mu.m, and the melting point of the crystalline syndiotactic-1,2-polybutadiene resin is not less than 110.degree. C. The compounding ratio of the resin is 5 to 60 parts by weight relative to 100 parts by weight of the rubber component. The rubber composition is useful for tires, other rubber articles, etc. With respect to tires in particular, a pneumatic tire includes a rubber composition used for a tread, wherein the rubber composition includes a rubber component and particulates of crystalline syndiotactic-1,2-polybutadiene resin. The matrix portion of the tread rubber other than the above particulates is preferably a foamed rubber.

Rubber composition and all season type pneumatic tires made from a

A process for producing a diolefin polymer or copolymer, comprising the steps of polymerizing 55-100 wt % of a conjugated diolefin with 0-45 wt % of an aromatic vinyl compound as monomers in a hydrocarbon as a solvent, by using initiators: a reaction product [a1] between at least one secondary amine compound (A) and an organic lithium compound and/or a lithium amide compound [a2] of the at least one secondary amine compound (A) as well as a reaction product [b1] between at least one alcohol (B) and an organic lithium compound and/or a lithium alkoxide compound of the at least one alcohol (B). A rubber composition containing not less than 30 wt % of such a diolefin polymer or copolymer with respect to an entire rubber component is also disclosed. This rubber composition exhibits excellent abrasion resistance, high tensile strength, steering stability and low rolling resistance, and is suitable for tires, particularly, as treads of low fuel consumption tires.

Process for producing a diolefin polymer or copolymer and a rubber

As a tread rubber of a pneumatic tire is used a rubber composition comprising 10-150 parts by weight of a silica filler, 0-150 parts by weight of carbon black and 0.2-10 parts by weight of at least one specified silane coupling agent, based on 100 parts by weight of a particular polymer rubber having a glass transition temperature of not lower than -50.degree. C. through polymerization of 1,3-butadiene or copolymerization of 1,3-butadiene and styrene with an organic alkali metal initiator, or a rubber blend of not less than 30 parts by weight of the above polymer and not more than 70 parts by weight of the other diene series rubber.

Pneumatic tires

A rubber composition satisfying wear resistance and fracture properties as well as wet skid resistance, ice skid resistance and dry gripping property is provided by including at least 30% by weight of a rubber ingredient which consists of 100 parts by weight of a particular branched styrene-butadiene copolymer (A) and 15-100 parts by weight of a particular low molecular weight butadiene polymer (B) and has a Mooney viscosity of 30-100.

Rubber compositions

There is a tire having tire performances such as wear resistance, cut resistance, heat build-up and the like and a processability simultaneously and economically improved by the application of a rubber composition containing a rubbery polymer modified with a silane compound and silica. The rubbery polymer modified with the silane compound is obtained by reacting an active terminal of a living polymer, which is obtained by polymerizing a monomer in the presence of an organic alkali metal catalyst, with a silane compound represented by the following general formula:

Tires made of silica filled, silane modified rubber

A rubber composition for tire having improved processability, wear resistance, rebound resilience and heat build-up comprises 20.about.70 parts by weight of a specified butadiene polymer, 30.about.80 parts by weight of at least one rubber selected from natural rubber, high cis-1,4 polyisoprene rubber and styrene-butadiene copolymer rubber, and 0.about.30 parts by weight of high cis-1,4 polybutadiene and/or low cis-1,4 polybutadiene, and contains 35.about.100 parts by weight of carbon black, 0.about.50 parts by weight of process oil, 0.5.about.5 parts by weight of aliphatic carboxylic acid and 0.1.about.3 parts by weight of sulfur based on 100 parts by weight of the above rubber components.

Rubber compositions from modified trans-polybutadiene and rubber for

A rubber composition is disclosed which contains not less than 20% by weight in a rubber component of a block copolymer composed of polymer or copolymer block units (A) and a random copolymer block units (B). The polymer or copolymer block units (A) are obtained by singly polymerizing a conjugated diolefine or copolymerizing the conjugated diolefine and a monovinyl aromatic hydrocarbon with use of a lithium initiator and contains not more than 10% by weight of the bound monovinyl aromatic hydrocarbon. The random copolymer block unit (B) are obtained by copolymerizing the conjugated diolefine and the monovinyl aromatic hydrocarbon and contain 15 to 80% by weight of the bound monovinyl aromatic hydrocarbon. In the block copolymer, (i) the block copolymer contains not less than 10% by weight of each of the block units (A) and the block units (B); (ii) the total content of the bound monovinyl aromatic hydrocarbon is from 10 to 40% by weight; (iii) the average content of the vinyl bonds in the conjugated diolefine portions is from 20 to 70%; and (iv) polymerizable terminals of the block copolymer are reacted with an isocyanate compound.

Vulcanized rubber composition

A rubber composition comprising not less than 20% by weight of an amino group-containing diene based polymer in a rubber component, and 10 to 100 parts by weight of silica as a filler with respect to 100 parts by weight of the rubber component. The amino group-containing diene based polymer is obtained by polymerizing a monomer or copolymerizing the monomer in an organic solvent in the presence of at least one of an organic alkali metal and an organic alkaline earth metal.

Rubber composition

A conjugated diene series rubber composition comprises, as a rubber component, (a) 20.about.100% by weight of a particular conjugated diene polymer and (b) a diene polymer rubber except for the polymer (a) and is excellent in the processability at unvulcanized state and the rebound resilience, strengths at rupture and wear resistance at vulcanized state.

Conjugated diene series rubber compositions

A butadiene-based rubber composition is disclosed, which contains not less than 20% by weight of a butadiene-based homopolymer or copolymer having a glass transition temperature (Tg) of not less than -105.degree. C., but less than -70.degree. C. and a Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 10 to 150. The butadiene-based homopolymer or copolymer is obtained by polymerizing butadiene or random-copolymerizing butadiene with at least one kind of a monomer selected from the group consisting of another conjugated diene and an aromatic vinyl compound, and then reacting polymerization-active terminals thereof with an isocyanate compound and/or an isothiocyanate compound. The butadiene-based rubber composition has excellent resilience, fracture strength, and wear resistance as a vulcanizate as well as excellent processability as an unvulcanized rubber, and can be used as tire applications such as tire treads, undertreads, sidewalls, bead portions, etc. as well as vibration insulating rubber, hoses, belts and other industrial articles.

Butadiene-based rubber composition

A rubber composition is disclosed which contains, as a rubber component, 20-100% by weight of (A) polybutadiene polymerized by using a lithium initiator and 80 to 0% by weight of (B) another rubber component. The polybutadiene has the following physical properties (i)-(v):

Polybutadiene rubber composition

A rubber composition containing not less than 20% of a conjugated diene based polymer or copolymer. The polymer or copolymer is obtained by polymerizing a conjugated diene or copolymerizing the conjugated diene with at least one kind of other conjugated diene and an aromatic vinyl compound with use of a lithium initiator, and then reacting an isocyanate compound with active terminals of the thus obtained polymer or copolymer. The conjugated diene is butadiene or isoprene, while other conjugated diene is selected from pentadiene, 2,3-dimethylbutadiene as well as isoprene and butadiene, and an aromatic vinyl compound may be styrene, vinyltoluene, .alpha.-methylstyrene, etc. The rubber composition is applicable as tread portion, carcass, side wall portion of tires, vibration resistant rubber, window frame, hose, and various industrial articles.

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Tokyo, Japan

Tatsuro Hamada