Sumitomo Rubber Industries Limited

Kensuke Washizu

Tatsuya Miyazaki

Takahiro Mabuchi

Takayuki Nagase

Toshifumi Haba

Kenya Watanabe

Hiroki Nakajima

Rie Yasuda

Shoko Nakahata

Kentaro Oishi

The present invention aims to provide rubber compositions and tires which provide improved overall performance in terms of wet grip performance and dry grip performance. The present invention relates to a rubber composition having a dynamic modulus E* that reversibly changes with water and satisfying the following relationship (1):Dynamic modulus*when water-wet/Dynamic modulus*when dry×100%≤90%  (1).

Rubber composition and tire

The present invention provides rubber compositions and tires which provide improved overall performance in terms of wet grip performance and dry grip performance. Included is a rubber composition having a hardness that reversibly changes with water, satisfying the relationships (1) and (2) below, and having a stress at break of 8.0 MPa or more,Hardness when dry−Hardness when water-wet≥1  (1)wherein each hardness represents the JIS-A hardness at 25° C. of the rubber composition,0.90≤Volume when water-wet/Volume when dry≤1.01  (2)wherein each volume represents the volume at 25° C. of the rubber composition.

The present disclosure aims to provide rubber compositions and tires which provide improved overall performance in terms of wet grip performance and dry grip performance. The present disclosure relates to a rubber composition having a hardness that reversibly changes with water and satisfying the following relationships (1) and (2): Hardness when dry−Hardness when water-wet≥1 (1) wherein each hardness represents the JIS-A hardness at 25° C. of the rubber composition; and tan δ at 70° C. when dry≥0.18 (2) wherein the tan δ at 70° C. represents the loss tangent measured at 70° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz.

The present invention aims to provide rubber compositions and tires which provide improved overall performance in terms of wet grip performance, dry grip performance, and fuel economy. The present invention relates to a rubber composition having a hardness that reversibly changes with water and satisfying the following relationships (1) and (2):Hardness when dry−Hardness when water-wet≥1  (1)wherein each hardness represents the JIS-A hardness at 25° C. of the rubber composition; andtan δ at 70° C. when dry<0.14  (2)wherein the tan δ at 70° C. represents the loss tangent measured at 70° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz.

The present invention aims to provide rubber compositions and tires which provide improved overall performance in terms of wet grip performance and dry grip performance. The present invention relates to a rubber composition having a hardness that reversibly changes with water and satisfying the following relationship (1):Hardness when dry−Hardness when water-wet≥10  (1)wherein each hardness represents the JIS-A hardness at 25° C. of the rubber composition.

Provided are copolymers which provide improved overall performance in terms of fuel economy and wet grip performance, as well as rubber compositions and tires containing the copolymers. Included is a copolymer obtained by copolymerizing an aromatic vinyl compound, a conjugated diene compound, and a compound represented by the formula (1) below or by copolymerizing a conjugated diene compound and a compound represented by the formula (1) below, the copolymer having a weight average molecular weight of 1.0&#xd7;10to 2.5&#xd7;10, wherein Rand Rmay be the same or different and each represents a functional group containing at least two selected from the group consisting of carbon, hydrogen, and silicon, and Rand Rmay be joined together to form a ring structure.

Copolymer, rubber composition, and tire

A pneumatic tire produced by processing a rubber composition including a hydrogenated branched conjugated diene copolymer produced by copolymerizing a branched conjugated diene compound and a vinyl compound to form a branched conjugated diene copolymer and hydrogenating the branched conjugated diene copolymer. The branched conjugated diene compound is represented by formula (1), where Ris an aliphatic hydrocarbon having 6 to 11 carbon atoms, the vinyl compound is represented by formula (3), where Ris a hydrogen atom, an aliphatic hydrocarbon group having 1 to 3 carbon atoms, an alicyclic hydrocarbon group having 3 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms.

Hydrogenated branched conjugated diene copolymer, rubber composition and pneumatic tire

The present invention provides a rubber composition excellent in grip performance, durability of grip performance, and abrasion resistance. Also provided is a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition exhibiting a temperature dependence curve of tan &#x3b4; with a half-width defined by Equation (1) of 45 or less as measured at a strain of 0.1% and a frequency of 10 Hz, the rubber composition having a temperature dependence of hardness defined by Equation (2) of 4.3 or less, the temperature dependence curve having a peak temperature of 10&#xb0; C. or lower,half-width=(temperature at half-peak height on high temperature side)&#x2212;(temperature at half-peak height on low temperature side),&#x2003;&#x2003;Equation (1):temperature dependence of hardness=(hardness index at 0&#xb0; C.)/(hardness index at 100&#xb0; C.).&#x2003;&#x2003;Equation (2):

Rubber composition and pneumatic tire

There is provided a process for preparing a branched conjugated diene polymer by copolymerizing 1 to 100% by weight of a branched conjugated diene compound (1) monomer: wherein Ris an aliphatic hydrocarbon having 6 to 11 carbon atoms, with 99 to 0% by weight of a conjugated diene compound (2) monomer: wherein Rand Rare the same or different and each is a hydrogen atom, or the like, and/or 99 to 0% by weight of a vinyl compound (3) monomer: wherein Ris an aliphatic hydrocarbon group having 6 to 10 carbon atoms, or the like,wherein the process comprises a step of polymerizing by adding a monomer solution successively into a catalyst solution. The branched conjugated diene polymer is useful as a rubber component for a tire for improving processability.

Preparation process of branched conjugated diene polymer

A pneumatic tire produced by processing a rubber composition including a hydrogenated branched conjugated diene copolymer produced by copolymerizing a branched conjugated diene compound and a vinyl compound to form a branched conjugated diene copolymer and hydrogenating the branched conjugated diene copolymer. The branched conjugated diene compound is represented by formula (1), where Ris an aliphatic hydrocarbon having 6 to 11 carbon atoms, the vinyl compound is represented by formula (3), where Ris a hydrogen atom, an aliphatic hydrocarbon group having 1 to 3 carbon atoms, an alicyclic hydrocarbon group having 3 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms, copolymerization ratio of the branched conjugated diene compound is 1 to 99% by weight, copolymerization ratio of the vinyl compound is 99 to 1% by weight, the branched conjugated diene compound is myrcene and/or farnesene, and the vinyl compound is styrene.

Provided is a studless winter tire which provides good performance on ice and snow and good abrasion resistance, and suffers little change in hardness and little discoloration on the tire surface. The present invention relates to a studless winter tire including a tread formed from a rubber composition containing a predetermined amount of a farnesene resin obtained by polymerizing farnesene. The present invention relates to a studless winter tire including a tread formed from a rubber composition containing a predetermined amount of at least one myrcene resin selected from the group consisting of myrcene polymers with a Mw of 1,000-500,000, myrcene-butadiene copolymers with a Mw of 1,000-500,000, and myrcene-styrene copolymers with a Mw of 1,000-150,000; and a predetermined amount of a silica with an NSA of 40-400 m/g, the rubber component containing a predetermined amount of a high-cis polybutadiene with a cis content of 95% by mass or more.

Studless winter tire

An object of the present invention is to provide a rubber composition for tire that is excellent in abrasion resistance, initial grip performance and stability of grip performance while maintaining processability. The rubber composition for tire comprises a diene rubber component, a hydrocarbon resin containing a component unit derived from a monomer component having a heteroatom or a hydrogenated product thereof (resin A) and a hydrocarbon resin that does not contain a component unit derived from a monomer component having a heteroatom or a hydrogenated product thereof (resin B), wherein a content ratio (mass ratio) of the resin B to the resin A is 0.1 to 50.

Rubber composition for tire

There is provided a branched conjugated diene copolymer prepared by copolymerizing 1 to 99% by weight of a branched conjugated diene compound (1): wherein Ris an aliphatic hydrocarbon having 6 to 11 carbon atoms, and 99 to 1% by weight of a conjugated diene compound (2): wherein Rand Rare the same or different and each is a hydrogen atom, or the like. The branched conjugated diene copolymer is useful as a rubber component of a rubber composition for a tire enhancing both of abrasion resistance and grip performance to a high level and exhibiting excellent processability.

Branched conjugated diene copolymer, rubber composition and pneumatic tire

There is provided a branched conjugated diene copolymer prepared by copolymerizing 1 to 99% by weight of a branched conjugated diene compound (1): wherein Ris an aliphatic hydrocarbon having 6 to 11 carbon atoms,less than 99% by weight of a conjugated diene compound (2): wherein Rand Rare the same or different and each is a hydrogen atom, or the like, andless than 99% by weight of a vinyl compound (3): wherein Ris an aromatic hydrocarbon group having 6 to 10 carbon atoms, or the like. The branched conjugated diene copolymer is useful as a rubber component of a rubber composition for a tire enhancing both of abrasion resistance and grip performance to a high level and exhibiting excellent processability.

The present invention relates to a branched conjugated diene copolymer which is useful for preparing a rubber composition, having high uniformity of a temperature dependence curve of a viscoelasticity tan &#x3b4;, for a tire, a rubber composition comprising the copolymer, and a pneumatic tire produced using the rubber composition for a tire. The branched conjugated diene copolymer is composed of monomer components comprising a branched conjugated diene compound represented by a general formula (1):  wherein Rrepresents an aliphatic hydrocarbon group having 6 to 11 carbon atoms, and an aromatic vinyl compound represented by a general formula (2):  wherein Rrepresents an aromatic hydrocarbon group having 6 to 10 carbon atoms, and Rrepresents a hydrogen atom or the like, and a copolymerization ratio (m) of the aromatic vinyl compound (2) is 45% by mass or more.

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Kobe, Japan

Kensuke Washizu