Sumitomo Rubber Industries Limited

Michio Hirayama

Takayuki Hattori

Kenichi Uesaka

Ai Matsuura

Yasuhisa Minagawa

A rubber composition for tires which enables a balanced improvement in rolling resistance, abrasion resistance, and wet-skid performance which contains a rubber blend, including a diene rubber A modified with a specific acrylamide compound, and a diene rubber B modified with either a combination of a specific silicon or tin compound and a specific modifying compound or with the modifying compound, the combined rubbers A and B having a weight average molecular weight of 300,000 to 1,400,000; and a specific silica.

Tire rubber composition and pneumatic tire

[Object] To provide a pneumatic tirefrom which static electricity is easily discharged. [Solution] The tireincludes penetration portions, an under tread, a belt, a carcass, and clinches. The carcassincludes a large number of cords aligned with each other, and a conductive topping rubber. The electric resistance Rc of the carcass which is represented by the following mathematical formula is less than 1.0&#xd7;10&#x3a9;./(2&#xd7;3.14&#xd7;)&#xd7;&#xd7;10In the mathematical formula, &#x3c1; is the volume resistivity (&#x3a9;&#xb7;cm) of the topping rubber of the carcass, g is the minimum thickness (mm) of the topping rubber, r is the distance (m) from the axis of the tire to an outer end, in the radial direction, of the clinch, and L is the length (m) of the carcass from an end of the reinforcing layer to the outer end, in the radial direction, of the clinch.

Pneumatic tire

The present invention aims to provide a tire having improved abrasion resistance and appearance, as well as reduced rolling resistance and therefore improved fuel economy. The present invention relates to a tire including a tread, the tread containing 0.9 to 1.5% by mass of a wax, 0.9 to 1.5% by mass of an amine antioxidant, 0.3 to 1.0% by mass of a quinoline antioxidant, and a tread rubber component containing 3% by mass or more of a polybutadiene rubber, the tread having a rubber thickness between a tread groove bottom and an outermost belt-reinforcing layer of 0.1 to 2.0 mm.

Tire

The present invention provides a rubber composition for tires which achieves a balanced improvement in rolling resistance, abrasion resistance, and wet-skid performance while providing excellent processability; and a pneumatic tire including the rubber composition. The present invention relates to a rubber composition for tires, including: a modified diene rubber A which has been terminally modified with a specific acrylamide compound; a modified diene rubber B which has been modified with a silicon or tin compound and a specific modifying compound or with the modifying compound; and a silane coupling agent containing a mercapto group, the modified diene rubbers A and B, taken as a whole, having a weight average molecular weight falling within a specific range.

Rubber composition for tire, and pneumatic tire

A method for estimating wear resistance of a tread portion of a tire comprises: a tire manufacturing step in which the tire to be evaluated is manufactured; a rubber seat sampling step in which an evaluation rubber seat is cut out from the tread portion of the tire to include a part of the tread surface; an abrasion step in which the rubber seat is subjected to abrasion by the use of an indoor wear testing machine; and a wear resistance estimating step in which the wear resistance of the tire is estimated based on a state of the wear of the rubber seat caused in the abrasion step.

Method for estimating wear resistance of tread portion of tire

The present invention provides a tire rubber composition with which the grip performance, the abrasion resistance, and the performance in terms of rolling resistance are improved in a balanced manner. The present invention relates to a tire rubber composition comprising: a modified diene rubber A which is modified with a specific acrylamide compound; and a modified diene rubber B which is modified with a specific modifying compound alone or together with a specific silicon or tin compound, a weight average molecular weight of a total of the modified diene rubbers A and B being 300,000 to 1,400,000.

The present invention provides a rubber composition for a tire in which the reaction rate between a silane coupling agent and silica is increased to enhance the fuel economy and the abrasion resistance, and a pneumatic tire comprising a component of any kind produced using the rubber composition for a tire. The present invention relates to a rubber composition for a tire, comprising: silica; a silane coupling agent; and at least one selected from the group consisting of a hydroxy acid, itaconic acid, and a salt thereof.

Rubber composition for tires and pneumatic tire

It is an object of the present invention to provide a tire rubber composition excellent in performances such as silica dispersibility and processability. The present invention relates to a tire rubber composition, comprising: a rubber component that contains an epoxidized natural rubber; silica; and a silane coupling agent, wherein the amount of the epoxidized natural rubber in 100% by mass of the rubber component is 15% by mass or more, the silica has a CTAB specific surface area of 180 m/g or more and a BET specific surface area of 185 m/g or more, and the silane coupling agent contains a mercapto group.

It is an object of the present invention to provide a tire rubber composition excellent in performances such as silica dispersibility and processability. The present invention relates to a tire rubber composition, comprising: a rubber component; silica; and a silane coupling agent, wherein the silica has a CTAB specific surface area of 180 m/g or more and a BET specific surface area of 185 m/g or more, and the silane coupling agent is a copolymer comprising units A represented by formula (1) and units B represented by formula (2), and the proportion of the units B is 1 to 70 mol % of the total molar amount of the units A and the units B. 

A pneumatic radial tire that can improve maneuver stability while maintaining riding comfort is provided. The pneumatic radial tire has a tire tread including at least two layers of a base tread and a cap tread arranged externally in a radial direction of the base tread. The base tread is formed by a base tread rubber composition including at least 2-20 parts by weight of a kraft paper ground product relative to 100 parts by weight of a rubber component. The base tread has its ratio E*a/E*b of a complex elastic modulus in a circumferential direction E*a to a complex elastic modulus in a tire radial direction E*b set to be at least 1.5, each of the complex elastic moduli E*a and E*b being measured at a temperature of 70&#xb0; C., a frequency of 10 Hz, and a dynamic strain of &#xb1;1% at a tire maximum width position in a state where the tire is attached to a rim and filled to a prescribed internal pressure.

Pneumatic radial tire having base tread and cap tread with the base tread including kraft paper ground product

The present invention provides a pneumatic radial tire, in which rolling resistance is reduced and durability is improved without losing toe-chip resistance when assembling the rim. More specifically, the present invention relates to a pneumatic radial tire having a chafer comprising a rubber composition having complex modulus of 9 to 13 MPa measured under conditions of temperature of 70&#xb0; C., frequency of 10 Hz and dynamic strain of &#xb1;2%, loss tangent of 0.08 to 0.11 and tensile elongation at break of at least 230% measured according to JIS-K6251.

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Kobe, Japan

Michio Hirayama