Abstract: Provided is rubber composition that can improve wear resistance and cutting resistance while having good fuel efficiency when applied to a tire. The rubber composition contains a rubber component containing natural rubber and/or synthetic isoprene rubber, and syndiotactic 1,2-polybutadiene, where the syndiotactic 1,2-polybutadiene has a crystal content of 7 J/g to 40 J/g and a number-average molecular weight of 6.5×104 or more.

Abstract: The present invention provides a conjugated diene polymer containing a low vinyl portion having a vinyl content of 2 to 20% by mol and a high vinyl portion having a vinyl content of 50% by mol or more, and a method for producing the same; a rubber composition containing a rubber component containing the conjugated diene polymer, at least one filler selected from the group consisting of carbon black and silica, a silane coupling agent, and a crosslinking agent; crosslinked rubber prepared by crosslinking the rubber composition; and a rubber product and a tire containing the crosslinked rubber. The tire can achieve both the abrasion resistance and the low fuel consumption capability, the conjugated diene polymer, the rubber composition, and the crosslinked rubber are preferred for producing the tire, and the rubber product is excellent in abrasion resistance and low heat generation property.

Abstract: An object of the present invention is to provide a multicomponent copolymer for use for producing a rubber composition and a rubber product having high abrasion resistance and wet performance. Further, the invention is to provide a rubber composition containing the multicomponent copolymer, a crosslinked rubber composition produced by crosslinking the rubber composition, and a tire and a rubber product using the rubber composition or the crosslinked rubber composition. The multicomponent copolymer of the invention contains a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit, wherein the content of the aromatic vinyl unit is 5 mol % or more and less than 50 mol % of the whole multicomponent copolymer and the content of the non-conjugated olefin unit is more than 0 mol % and 50 mol % or less of the whole multicomponent copolymer.

Abstract: The present invention provides a conjugated diene polymer containing a low vinyl portion having a vinyl content of 2 to 20% by mol and a high vinyl portion having a vinyl content of 50% by mol or more, and a method for producing the same; a rubber composition containing a rubber component containing the conjugated diene polymer, at least one filler selected from the group consisting of carbon black and silica, a silane coupling agent, and a crosslinking agent; crosslinked rubber prepared by crosslinking the rubber composition; and a rubber product and a tire containing the crosslinked rubber. The tire can achieve both the abrasion resistance and the low fuel consumption capability, the conjugated diene polymer, the rubber composition, and the crosslinked rubber are preferred for producing the tire, and the rubber product is excellent in abrasion resistance and low heat generation property.

Abstract: An object of the present invention is to provide a multicomponent copolymer for use for producing a rubber composition and a rubber product having high abrasion resistance and wet performance. Further, the invention is to provide a rubber composition containing the multicomponent copolymer, a crosslinked rubber composition produced by crosslinking the rubber composition, and a tire and a rubber product using the rubber composition or the crosslinked rubber composition. The multicomponent copolymer of the invention contains a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit, wherein the content of the aromatic vinyl unit is 5 mol % or more and less than 50 mol % of the whole multicomponent copolymer and the content of the non-conjugated olefin unit is more than 0 mol % and 50 mol % or less of the whole multicomponent copolymer.

Abstract: The present invention relates to: a rubber composition comprising a matrix of a nonpolar conjugated diene polymer in which domains formed from an olefin polymer are dispersed, the matrix and the domain having an interface therebetween in which a chemical bond exists after vulcanization, the domain having a dynamic compressive complex elastic modulus (Ec*) of 10 MPa or less; or a rubber composition comprising a matrix of a nonpolar conjugated diene polymer in which domains formed from an olefin polymer are dispersed, the matrix and the domain having an interface therebetween in which a chemical bond exists after vulcanization, with an average distance between the domains of 2 ?m or less. A rubber composition for improving the ozone resistance and a tire having improved ozone resistance are provided.