Bridgestone Corporation

Mitsubishi Denki Kabushiki Kaisha

Ube Industries, Inc.

Masanori Aoyama

Satoshi Nishida

Eiji Yamanaka

Tatsuro Hamada

Hiroyuki Teratani

Seiichiro Iwafune

Yoshiyuki Morimoto

Koji Yamauchi

Koichi Nagakura

Koji Ishiguchi

Motohide Tamura

There are provided a pneumatic radial tire of heavy load vehicles, in which durability of a belt is improved. A pneumatic radial tire for heavy load vehicles comprises a pair of bead portions in each of which a bead core is embedded, a radial carcass plyextending from one bead portion to the other bead portion and turned around the bead core from an inner side to an outer side of the bead core in a width direction of the tire and at least six belt layersdisposed on an outer side of this radial carcass plyin a radial direction of the tire, wherein the following relations are satisfied: W&#x3e;W&#x3e;W, where Wis a maximum width of first and second beltsf the belt layers, Wis a maximum width of third and forth beltsof the belt layersand Wis a maximum width of fifth and sixth beltsof the belt layers; and&#x3e;D/D, where Dis a cord diameter of the first and second belts and Dis a cord diameter of the third and forth belts. In addition, a steel cord of each belt layer has a double twist structure in which a plurality of steel filaments are twisted to form a cable and two to ten cables are further twisted.

Pneumatic radial tire for heavy load

Provided are a steel cord for reinforcing rubber whose fatigue resistance is increased more than ever to enable achieving high durability that was not conventionally realized, and a pneumatic radial tire including the steel cord as a reinforcement member. In a steel cord for reinforcing rubber having a double-twist structure that includes a plurality of strands twisted together in the same direction with the same pitch and including a central structure and at least one outer layer, the central structure is composed of at least two strands being twisted around each other and each being composed of at least seven filaments being twisted together. In a steel cord for reinforcing rubber including at least three core strands being twisted together and at least six sheath strands being twisted together around the core strands, the core strands and the sheath strands are twisted in the same direction.

Steel cord for reinforcing rubber and pneumatic radial tire

A laser oscillator includes: electrode tubes, for employing a discharge to excite a laser gas, and for generating a laser beam; a box, for storing parts, such as the electrode tubes; and an optical catalyst layer, which is formed on the inner walls of the box

Laser oscillator

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 pneumatic tire for all seasons comprises a tread provided with a foamed rubber containing a given amount of a particular resin such as crystalline syndiotactic 1,2 -polybutadiene having specified hardness and average particle size, and having specified expansion ratio, average expanded cell size and storage modulus (E') at -20.degree. C. of a given range, and exhibits satisfactory braking and traction performances at not only dry-on-ice state but also wet-on-ice state while sufficiently holding the steering stability, durability and low fuel consumption in summer season.

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Tokyo, Japan

Masanori Aoyama