Rubber components of a tire comprising a diene elastomer and at least 1 phr of reduced graphene oxide nanoparticles having a specific surface area of at least 700 m.sup.2/g, an oxygen content of no more than 6 at %, and a ratio of non-aromaticity to aromaticity I.sub.D/I.sub.G of at least 0.7 as determined by Raman spectroscopy. Methods of preparing such rubber compositions in an internal mixer for achieving good distribution and dispersion are also included.

To provide a method for producing a multicomponent copolymer with which a multicomponent copolymer having excellent rupture strength can be obtained, and a multicomponent copolymer, a rubber composition and a tire having excellent rupture strength. The method is a method for producing a multicomponent copolymer having a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit, comprising adding a conjugated diene compound in divided portions into a reactor containing a catalyst and at least one selected from the group consisting of a non-conjugated olefin compound and an aromatic vinyl compound. The multicomponent copolymer is obtained with the production method. The rubber composition comprises the multicomponent copolymer as a rubber component. The tire uses the rubber composition.

To provide a method for producing a multicomponent copolymer with which a multicomponent copolymer having excellent rupture strength can be obtained, and a multicomponent copolymer, a rubber composition and a tire having excellent rupture strength. The method is a method for producing a multicomponent copolymer having a conjugated diene unit, a non-conjugated olefin unit and an aromatic vinyl unit, comprising adding a conjugated diene compound in divided portions into a reactor containing a catalyst and at least one selected from the group consisting of a non-conjugated olefin compound and an aromatic vinyl compound. The multicomponent copolymer is obtained with the production method. The rubber composition comprises the multicomponent copolymer as a rubber component. The tire uses the rubber composition.

A rubber composition for a tire, which does not require the addition of a compound when synthesizing rubber component and the modification of a rubber component, and a studless tire using the rubber composition are provided. The rubber composition for a tire contains fine particles of rotaxane having a straight chain molecule, a cyclic molecule clathrating the straight chain molecule and blocking groups arranged at both terminals of the straight chain molecule such that the cyclic molecule does not desorb from the straight chain molecule, covered with silica; a rubber component including natural rubber and butadiene rubber; and carbon black, wherein the total content of the fine particles and the carbon black is 30 to 60 parts by mass per 100 parts by mass of the rubber component.

Disclosed is a rubber composition which suppresses poor mixing or poor dispersion from occurring between an organic polymer material derived from natural rubber and an inorganic material such as silica and exhibits excellent viscoelastic properties, and a silane coupling agent composition used in the same. Also disclosed is a silane coupling agent composition comprising a protein modifying agent and a silane compound represented by Formula (1):

##STR00001##

wherein each of the variables is as defined herein.

Disclosed is a rubber composition which suppresses poor mixing or poor dispersion from occurring between an organic polymer material derived from natural rubber and an inorganic material such as silica and exhibits excellent viscoelastic properties, and a silane coupling agent composition used in the same. Also disclosed is a silane coupling agent composition comprising a protein modifying agent and a silane compound represented by Formula (1):

##STR00001##

wherein each of the variables is as defined herein.

Provided is a rubber composition comprising at least NBR as a rubber component and having rubber-metal adhesiveness equal to or higher than that of a rubber composition comprising a cobalt salt. The rubber composition comprises a rubber component, and a rubber-metal adhesion promoter, where the rubber component comprises at least 10 parts by mass of NBR per 100 parts by mass of the rubber component, the rubber-metal adhesion promoter comprises at least one selected from the group consisting of a metal salt of an aliphatic carboxylic acid (1) and a compound (2) having a specific structure.

Provided is a rubber composition comprising at least NBR as a rubber component and having rubber-metal adhesiveness equal to or higher than that of a rubber composition comprising a cobalt salt. The rubber composition comprises a rubber component, and a rubber-metal adhesion promoter, where the rubber component comprises at least 10 parts by mass of NBR per 100 parts by mass of the rubber component, the rubber-metal adhesion promoter comprises at least one selected from the group consisting of a metal salt of an aliphatic carboxylic acid (1) and a compound (2) having a specific structure.

A method for producing a modified conjugated diene-based polymer includes polymerizing a monomer including a conjugated diene compound in the presence of an alkali metal compound or an alkali earth metal compound to obtain a polymer having an active terminal; (a modification) reacting the polymer having an active terminal with a compound [M] having a plurality of hydrocarbyloxysilyl groups to obtain a modified polymer; and a mixing the modified polymer with at least one compound [C] selected from a compound [N] having one hydrocarbyloxysilyl group and an alcohol having 6 to 20 carbon atoms.

The present invention is directed to a rubber composition comprising an elastomer, a filler, and a block-copolymer. According to the invention, the block-copolymer comprises (i) an elastomer block and (ii) a thermoplastic block comprising a poly alkylacrylate, wherein the alkylacrylate comprises a polycyclic substituent at its single bonded oxygen atom. Moreover, the present invention is directed to a block-copolymer.