Abstract: The invention provides a method for producing a modified conjugated diene (co)polymer, the method including comprising: a modification reaction step including causing an organic silane compound to react with a conjugated diene (co)polymer having an active site at the active site, the organic silane compound having a characteristic group for forming a silanol group through hydrolysis and, in the vicinity of the characteristic group, (i) a functional group which binds the organic silane compound to the conjugated diene (co)polymer via addition to or substitution at the active site and which promotes reaction between the silanol group and a reinforcing filler after the addition or substitution reaction, or (ii) a functional group which promotes reaction between the silanol group and a reinforcing filler, and a hydrolyzation step performed after the modification reaction step; a modified conjugated diene (co)polymer having, at a molecular end of the conjugated diene (co)polymer, a silanol group, and a functional

Abstract: A process for producing a modified conjugated diene based polymer includes a step (a) of reacting a silicon compound with a conjugated diene based polymer having an active end so that the reaction takes place at the active end, the silicon compound having a protected primary amino group in the molecule thereof and a silicon atom to which a hydrocarbyloxy group and a reactive group are bonded, to thereby modify the active end, and a step (b) of performing condensation reaction, in the presence of a titanium compound serving as a titanium-based condensation-accelerating agent. A rubber composition contains the modified diene polymer, and a tire is produced from the rubber composition.

Abstract: A rubber composition for tire sidewall which comprises a rubber component, which comprises polybutadiene rubber having a content of the cis-1,4-bond of 92% or greater and a content of the vinyl bond of 1.5% or smaller and natural rubber and/or at least one other diene-based synthetic rubber, and 10 to 70 parts by mass of carbon black having a specific surface area by nitrogen adsorption of 20 to 100 m2/g per 100 parts by mass of the rubber component and does not comprise a softener having an aniline point of 50° C. or lower and a tire using the rubber composition for sidewall. Excellent resistance to cut growth is obtained while sufficient workability is surely exhibited.

Abstract: This invention relates to a rubber composition having a high storage modulus (G?) and a low loss tangent (tan ?), and more particularly to a rubber composition comprising 2 to 60 parts by mass of a low-molecular weight aromatic vinyl compound-conjugated diene compound copolymer (B) having an aromatic vinyl compound content of 5 to 80% by mass, a vinyl bond content in a conjugated diene compound portion of 5 to 80% by mass, a weight average molecular weight as measured through a gel permeation chromatography and converted to polystyrene of 5,000 to 500,000 and at least one functional group based on 100 parts by mass of a rubber component (A) composed of at least one of natural rubber and synthetic diene-based rubbers.

Abstract: The invention provides a method for producing a modified conjugated diene (co)polymer, the method including comprising: a modification reaction step including causing an organic silane compound to react with a conjugated diene (co)polymer having an active site at the active site, the organic silane compound having a characteristic group for forming a silanol group through hydrolysis and, in the vicinity of the characteristic group, (i) a functional group which binds the organic silane compound to the conjugated diene (co)polymer via addition to or substitution at the active site and which promotes reaction between the silanol group and a reinforcing filler after the addition or substitution reaction, or (ii) a functional group which promotes reaction between the silanol group and a reinforcing filler, and a hydrolyzation step performed after the modification reaction step; a modified conjugated diene (co)polymer having, at a molecular end of the conjugated diene (co)polymer, a silanol group, and a functional

Abstract: This invention relates to a rubber composition having excellent workability, fracture characteristics and wear resistance and a low heat buildup and a high storage modulus (G?), and more particularly to a rubber composition comprising not less than 20 parts by mass of a reinforcing filler (B) and 5 to 60 parts by mass of a low-molecular weight aromatic vinyl compound-conjugated diene compound copolymer (C) having an aromatic vinyl compound content of 5 to 80% by mass, a vinyl bond content in a conjugated diene compound portion of 10 to 80% by mass and a weight average molecular weight as measured with a gel permeation chromatography and converted to polystyrene of 5,000 to 300,000 based on 100 parts by mass of a rubber component (A) containing not less than 10% by mass of a modified conjugated diene-based polymer having at least one functional group.

Abstract: A rubber composition comprises 10 to 70 parts by mass of carbon black having 20 to 100 m2/g of the specific surface area by nitrogen adsorption per 100 parts by mass of a rubber component comprising 20 to 80 parts by mass of a modified polybutadiene rubber and 80 to 20 parts by mass of natural rubber and/or at least one other diene-based synthetic rubber, wherein the modified polybutadiene is obtained by polymerizing 1,3-butadiene in an organic solvent using a compound having a rare earth element of the lanthanoid series, followed by modifying the obtained polybutadiene, and has a content of the cis-1,4-bond of 92% or greater, a content of vinyl bond of 1.5% or smaller and a fraction of the modified chain end of 20% or greater; and a tire using the rubber composition for a sidewall. The rubber composition exhibits excellent low heat buildup property and resistance to fracture.

Abstract: The invention provides a process for producing a modified conjugated diene based polymer which attains favorable interaction between a rubber component and carbon black and/or silica, thereby improving dispersibility of the fillers, and which exhibits excellent properties such as heat-buildup-suppressing performance, fracture characteristics, and wear resistance; a modified conjugated diene based polymer produced through the process; a rubber composition containing the diene polymer; and a tire produced from the rubber composition and exhibiting the above properties.

Abstract: This invention relates to a rubber composition having excellent workability, fracture characteristics and wear resistance and a low heat buildup and a high storage modulus (G?), and more particularly to a rubber composition comprising not less than 20 parts by mass of a reinforcing filler (B) and 5 to 60 parts by mass of a low-molecular weight aromatic vinyl compound-conjugated diene compound copolymer (C) having an aromatic vinyl compound content of 5 to 80% by mass, a vinyl bond content in a conjugated diene compound portion of 10 to 80% by mass and a weight average molecular weight as measured with a gel permeation chromatography and converted to polystyrene of 5,000 to 300,000 based on 100 parts by mass of a rubber component (A) containing not less than 10% by mass of a modified conjugated diene-based polymer having at least one functional group.

Abstract: A rubber composition for tire sidewall which comprises a rubber component, which comprises polybutadiene rubber having a content of the cis-1,4-bond of 92% or greater and a content of the vinyl bond of 1.5% or smaller and natural rubber and/or at least one other diene-based synthetic rubber, and 10 to 70 parts by mass of carbon black having a specific surface area by nitrogen adsorption of 20 to 100 m2/g per 100 parts by mass of the rubber component and does not comprise a softener having an aniline point of 50° C. or lower and a tire using the rubber composition for sidewall. Excellent resistance to cut growth is obtained while sufficient workability is surely exhibited.

Abstract: A method for producing a rubber-filler master batch which comprises mixing a rubber solution obtained by dissolving a diene-based rubber in an organic solvent into a slurry obtained by dispersing in water, in advance, carbon black, silica and/or at least one inorganic filler represented by the following general formula (I): nM1.xSiOy.zH2O??(I) [wherein M1 represents at least one selected from the group consisting of metals which are aluminum, magnesium, titanium, calcium and zirconium, oxides and hydroxides of the metals, hydrates thereof and carbonates of the metals, and n, x, y and z respectively represent an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5 and an integer of 0 to 10.

Abstract: This invention relates to a rubber composition having a high storage modulus (G?) and a low loss tangent (tan ?), and more particularly to a rubber composition comprising 2 to 60 parts by mass of a low-molecular weight aromatic vinyl compound-conjugated diene compound copolymer (B) having an aromatic vinyl compound content of 5 to 80% by mass, a vinyl bond content in a conjugated diene compound portion of 5 to 80% by mass, a weight average molecular weight as measured through a gel permeation chromatography and converted to polystyrene of 5,000 to 500,000 and at least one functional group based on 100 parts by mass of a rubber component (A) composed of at least one of natural rubber and synthetic diene-based rubbers.