Bridgestone Corporation

Ube Industries, Inc.

Shikoku Chemicals Corporation

Seiichiro Iwafune

Toshiro Iwata

Hiroshi Mouri

Yasuyoshi Kawaguchi

Michio Ishii

Eiji Yamanaka

Kenji Matsuo

Tatsuro Hamada

Toshiyuki Ohta

Kojiro Yamaguchi

Eiji Takiguchi

Masanori Aoyama

Koji Yamauchi

Yoshiyuki Morimoto

Koichi Nagakura

Koji Ishiguchi

Masaaki Morimoto

Jun Sakiyama

Rubber composition for tire treads

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

Herein disclosed is a pneumatic tire which comprises a case and a tread which covers a crown portion of the case. The tread includes a foamed rubber which has a volume not less than 10% of that of the entire of the tread, and the foamed rubber is formed of a rubber composition which contains rubber components each having a glass transition point not higher than -60.degree. C.

Pneumatic tire with foam rubber in the tread

A pneumatic tire having excellent tire performances in winter and summer seasons comprises a tread, a part of which is comprised of an expanded rubber in a volume corresponding to at least 10% of the total volume of the tread at its surface. This expanded rubber contains particular rubber component and particular high reinforcing carbon black and oil, and has particular number of closed cells having a specified cell diameter to the total number of closed cells. Furthermore, a rubber reinforcing layer is arranged near to the tread shoulder.

Pneumatic tire having expanded outer tread rubber layer

Pneumatic tire having foamed tread rubber

A rubber composition contains granules of two-layer structure composed of insoluble sulfur powder treated with .alpha.-methylstyrene and a process oil as a vulcanizing agent. In this case, the content of process oil in the inner layer portion of the granule is larger than that in the outer layer portion thereof.

Rubber compositions with granules of sulfur, oil and methylstyrene

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Tokyo, Japan

Seiichiro Iwafune