Bridgestone Corporation

Hiroyuki Yokokura

Hidenobu Akahane

Masahiko Yamamoto

Hiroshi Takada

Daisuke Maehara

Fuyuki Terasaka

Shintaro Shimada

Yuta Hoshino

Yugo Zuigyo

Daisuke Ozaki

Humihiro Shiraishi

Junko Saito

Masahiro Yamaguchi

Provided is a tire whose durability is improved by using, as a reinforcing member, a polyester cord having an improved heat resistant adhesive property to rubber. Provided is a tire in which a rubber-cord complex composed of a polyester cord and a rubber is used as a reinforcing member. The polyester cord is formed by twisting polyester filaments, and then subjecting the twisted filaments to an adhesive agent treatment. The polyester filament is made of a polyester fiber which is composed of a polyester having ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.85 or higher, wherein the amount of terminal carboxy group in the fiber is 20 equivalent/ton or larger, the long period according to small-angle X-ray diffraction is 9 to 12 nm, and a surface treatment agent having an epoxy group is attached to the surface of the fiber.

Tire

A pneumatic tire having a reduced weight and improved durability is provided. In this pneumatic tire, at least one of the carcass ply and belt plies or the belt-reinforcement layer is constituted of reinforcing cords being para-aramid cords, and the para-aramid cords satisfy the relationship represented by the following formulae (I) to (III):&#x2266;32.14&#xd7;&#x2212;236&#x2003;&#x2003;(I)&#x2267;150&#x2003;&#x2003;(II)&#x2266;19&#x2003;&#x2003;(III)(where E represents a modulus of elasticity (cN/dtex) at 25&#xb0; C. under a load of 49 N, and T represents a tensile strength (cN/dtex)).

Pneumatic tire

This invention provides a pneumatic tire provided with a carcass () comprised of one or more carcass plies formed by covering plural reinforcing cords arranged in parallel with a coating rubber and a pair of side reinforcing rubber layers () each having a crescent shape in section and disposed at an inside of the carcass, wherein ride comfort during usual running and durability during run-flat running are improved by applying a cord including a polyketone fiber and satisfying conditions of equation (I): &#x3c3;&#x2267;&#x2212;0.01&#xd7;E+1.2 and equation (II): &#x3c3;&#x2267;0.02 [wherein &#x3c3; is a heat shrinkage stress (cN/dtex) at 177&#xb0; C. and E is an elastic modulus (cN/dtex) at 25&#xb0; C. under a load of 49 N] to the reinforcing cord and a rubber composition having a loss tangent (tan &#x3b4;) at 25&#xb0; C. and 1% strain of less than 0.12 and a viscosity (G') at 130&#xb0; C. during unvulcanization of not less than 50 MPa to the coating rubber.

A pneumatic radial tire for a passenger car having a pair of bead portions and a carcass having at least one carcass ply toroidally extending between a pair of bead cores embedded in the respective bead portions and containing organic fiber cords. The organic fiber cord is a polyketone fiber cord satisfying the following equation: &#x3c3;&#x2267;&#x2212;0.01E+1.2 and &#x3c3;&#x2267;0.02, where &#x3c3; is a thermal shrinkage stress at 177&#xb0; C. (cN/dtex) and E is an elastic modulus at 25&#xb0; C. under a load of 49N (cN/dtex). The cord has a ply-twisting coefficient Nof 0.35-0.70 and a cable-twisting coefficient Nof 0.50-0.95, where N=n&#xd7;(0.125&#xd7;D/&#x3c1;)&#xd7;10=n&#xd7;(0.125&#xd7;D/&#x3c1;)&#xd7;10is a ply twisting number (turns/10 cm), nis a cable twisting number (turns/10 cm), Dis dtext of ply-twisted yarn, Dis a total dtex, and &#x3c1; is a specific gravity of the cord (g/cm).

Pneumatic radial tire for passenger car

This invention relates to a tire having an improved durability in the run-flat running without damaging the ride comfort in the usual running, and more particularly to a run-flat tire comprising a sidewall portion provided with a side reinforcing rubber layer having a crescent shape at section wherein a cord layer including a polyketone fiber cord satisfying the following conditions of the following equations (I) and (II):&#x3c3;&#x2267;&#x2212;0.01&#xd7;+1.2&#x2003;&#x2003;(I)&#x3c3;&#x2267;0.02&#x2003;&#x2003;(II)[wherein &#x3c3; is a thermal shrinkage stress at 177&#xb0; C. (cN/dtex) and E is an elastic modulus at 25&#xb0; C. under a load of 49 N (cN/dtex)] is disposed in at least a part of a region A ranging from a belt end to a maximum width part of a tire side portion and a region B ranging from a neighborhood of a bead core to a bead filler.

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Kodaira, Japan

Hiroyuki Yokokura