Abstract: A process for simply and inexpensively producing a conjugated diene polymer with a narrow molecular weight distribution and a high cis-bond content at a low cost is provided. The process comprises a polymerization step, wherein a conjugated diene polymer having a cis-1,4-bond content of 98.5 mass % or more and a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography of 2.5 or less is obtained by carrying out a polymerization reaction in conjugated diene compounds using a catalyst composition containing a rare earth element-containing compound or a reaction product of the rare earth element-containing compound with a Lewis base, an aluminoxane and/or organoaluminum compound, and an iodine-containing compound.

Abstract: A process for simply and inexpensively producing a conjugated diene polymer with a narrow molecular weight distribution and a high cis-bond content at a low cost is provided. The process comprises a polymerization step, wherein a conjugated diene polymer having a cis-1,4-bond content of 98.5 mass % or more and a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography of 2.5 or less is obtained by carrying out a polymerization reaction in conjugated diene compounds using a catalyst composition containing a rare earth element-containing compound or a reaction product of the rare earth element-containing compound with a Lewis base, an aluminoxane and/or organoaluminum compound, and an iodine-containing compound.

Abstract: This invention provides a rubber composition being excellent in the workability during production and the heat resistance and high in the storage elastic modulus (G?) and small in the loss tangent (tan ?), which is formed by compounding 1-60 parts by mass of a low-molecular weight conjugated diene-based polymer (B) having a weight average molecular weight as measured through a gel permeation chromatography and converted to polystyrene of 10,000-200,000 and a vinyl bond content in a conjugated diene compound portion of not less than 40% based on 100 parts by mass of a rubber component (A) comprised of at least one selected from the group consisting of natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber and isobutylene isoprene rubber, wherein the rubber component (A) comprises natural rubber and/or polyisoprene rubber and a proportion of styrene units in total of the low-molecular weight conjugated diene-based polymer (B) is less than 5% by mass.

Abstract: This invention relates to a rubber composition which has an excellent processability but also improves a storage modulus (G?) and loss tangent (tan ?) at a low temperature and further improves a wear resistance, and more particularly to a rubber composition characterized by compounding more than 1 part by mass but less than 30 parts by mass of a low-molecular weight polymer component (B) having an amount of an aromatic vinyl compound bonded of less than 30 mass % and a weight average molecular weight as converted to polystyrene of 0.2×104-8.0×104 and not less than 5 parts by mass of a filler (C) based on 100 parts by mass of a high-molecular weight polymer component (A) having an amount of an aromatic vinyl compound bonded of not more than 80 mass % and a weight average molecular weight as converted to polystyrene of not less than 1.

Abstract: A process for producing a modified conjugated diene polymer includes subjecting an active terminal of a conjugated diene polymer having a vinyl content of less than 10% and a cis-1,4 bond content of 75% or more to a modification reaction with an alkoxysilane compound, and subjecting the alkoxysilane compound (residue) to a condensation reaction in an aqueous solution at a pH of 9 to 14 and a temperature of 85 to 180° C. in the presence of a condensation accelerator including a compound containing titanium. The modified conjugated diene polymer exhibits low heat build-up and increased reinforcing properties when used for a rubber composition, and exhibits excellent wear resistance, mechanical characteristics, and processability.

Abstract: A process for producing a modified conjugated diene polymer includes subjecting an active terminal of a conjugated diene polymer having a vinyl content of less than 10% and a cis-1,4 bond content of 75% or more to a modification reaction with an alkoxysilane compound, and subjecting the alkoxysilane compound (residue) to a condensation reaction in an aqueous solution at a pH of 9 to 14 and a temperature of 85 to 180° C. in the presence of a condensation accelerator including a compound containing titanium. The modified conjugated diene polymer exhibits low heat build-up and increased reinforcing properties when used for a rubber composition, and exhibits excellent wear resistance, mechanical characteristics, and processability.

Abstract: A method for preparing a functionalized polymer comprising the steps of preparing a pseudo-living polymer by polymerizing conjugated diene monomer with a lanthanide-based catalyst, and reacting the pseudo-living polymer with at least one functionalizing agent defined by the formula (I) where A is a substituent that will undergo an addition reaction with a pseudo-living polymer, R1 is a divalent organic group, R2 is a monovalent organic group, and each R4, which may be the same or different, is a monovalent organic group or a substituent defined by —OR5 where R5 is a monovalent organic group, with the proviso that A, R1, R2, R4, and R5 are substituents that will not protonate a pseudo-living polymer. Also, the functionalized polymer and a vulcanizable composition containing the polymer.

Abstract: A method for preparing a functionalized polymer comprising the steps of preparing a polymer by polymerizing conjugated diene monomer with a lanthanide-based catalyst, wherein the lanthanide-based catalyst comprises (a) a lanthanide compound, (b) an alkylating agent, and (c) a source of halogen, and reacting the pseudo-living polymer with at least one amide-containing functionalizing agent.

Abstract: A reduced oil rubber composition includes (a) a silica filler, (b) a N-substituted polyalkylene succinimide derivative, and (c) a rubber matrix. In certain embodiments, the composition may comprise a reduced amount of oil, especially a reduced amount of aromatic oil or even no aromatic oil. Rubber articles manufactured from such composition, such as tires and power belts, have improved properties such as reduced rolling resistance, improved wet/snow traction and winter softness, improved dynamic stiffness, improved tensile strength, easy handling, and/or compatibility with higher environmental standard, among others.

Abstract: A functionalized polymer prepared by a process comprising the steps of preparing a pseudo-living polymer by polymerizing conjugated diene monomer with a lanthanide-based catalyst, the polymer having greater than about 85 percent in the 1,4-cis microstructure and less than about 3 percent in the 1,2- or 3,4-microstructure, and reacting the pseudo-living polymer with at least one functionalizing agent defined by the formula (I) or (II): where Z is a substituent that will react or interact with organic or inorganic fillers; with the proviso that each group attached to the imino carbon is attached via a carbon atom and R1, R2, R3, R4, R5, R13, R14 and Z are substituents that will not protonate a pseudo-living polymer.

Abstract: A process for producing a modified polymer that exhibits low rolling resistance, excellent mechanical properties (e.g., tensile strength), high wet-skid resistance, and excellent wear resistance when vulcanized, a modified polymer obtained by the process, and a rubber composition containing the same. The process includes subjecting an alkali metal active end of a conjugated diene polymer to a modification reaction with an alkoxysilane compound, the conjugated diene polymer being produced by subjecting a diene monomer or a diene monomer and a monomer other than the diene monomer to anionic polymerization in a hydrocarbon solvent using an alkali metal initiator, and subjecting the resulting product to a condensation reaction in the presence of a condensation accelerator that includes a compound of at least one element among the elements of the groups 4A (excluding Ti), 2B, 3B, and 5B of the periodic table.

Abstract: This invention provides a rubber composition highly balancing flexibility at a low temperature and a low rolling resistance, which is formed by compounding a low-molecular weight conjugated diene-based polymer (B) having at least one functional group, an aromatic vinyl compound content of less than 5% by mass and a weight average molecular weight as measured without terminating by modification through a gel permeation chromatography and converted to polystyrene of not less than 2,000 but less than 150,000 and a filler (C) into a high-molecular weight rubber component (A) having a weight average molecular weight as measured without terminating by modification through a gel permeation chromatography and converted to polystyrene of not less than 150,000.

Abstract: A functionalized polymer prepared by a process comprising the steps of preparing a pseudo-living polymer by polymerizing conjugated monomer with a lanthanide-based catalyst, and reacting the pseudo-living polymer with a functionalizing agent defined by the formula (I) A-R1-Z??(I) where R1 is a divalent bond or divalent organic group comprising from 0 to about 20 carbon atoms, A is a substituent that will undergo an addition reaction with a pseudo-living polymer, and Z is a substituent that will react or interact with silica or carbon black reinforcing fillers, with the proviso that A, R1, and Z are substituents that will not protonate a pseudo-living polymer.

Abstract: A process for simply and inexpensively producing a conjugated diene polymer with a narrow molecular weight distribution and a high cis-bond content at a low cost is provided. The process comprises a polymerization step, wherein a conjugated diene polymer having a cis-1,4-bond content of 98.5 mass % or more and a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography of 2.5 or less is obtained by carrying out a polymerization reaction in conjugated diene compounds using a catalyst composition containing a rare earth element-containing compound or a reaction product of the rare earth element-containing compound with a Lewis base, an aluminoxane and/or organoaluminum compound, and an iodine-containing compound.

Abstract: This invention relates to a styrene-based (co)polymer capable of improving tan ? of a rubber composition while ensuring a fracture resistance of the rubber composition by adding to the rubber composition, and more particularly to a styrene-based polymer obtained by homopolymerizing a styrene derivative and having a weight average molecular weight as converted to polystyrene of 2×103 to 50×103, and a styrene-based copolymer obtained by copolymerizing styrene and at least one of styrene derivatives and having a weight average molecular weight as converted to polystyrene of 2×103 to 50×103.

Abstract: A reduced oil rubber composition includes (a) a silica filler, (b) a N-substituted polyalkylene succinimide derivative, and (c) a rubber matrix. In certain embodiments, the composition may comprise a reduced amount of oil, especially a reduced amount of aromatic oil or even no aromatic oil. Rubber articles manufactured from such composition, such as tires and power belts, have improved properties such as reduced rolling resistance, improved wet/snow traction and winter softness, improved dynamic stiffness, improved tensile strength, easy handling, and/or compatibility with higher environmental standard, among others.

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: There is provided a rubber composition exhibiting excellent storage modulus and loss factor without damaging the operability. The rubber composition is characterized by containing 5-60 parts by mass of an aromatic vinyl compound-diene compound copolymer (B) having a weight average molecular weight of 5,000-300,000 (conversion to polystyrene through gel permeation chromatography) based on 100 parts by mass of a rubber component comprising at least one rubber of natural rubber and synthetic diene-based rubbers in which the copolymer (B) comprises 5-80 mass % of the aromatic vinyl compound and a vinyl bond content in diene compound portion is 10-80 mass %. This rubber composition can be used in a tread compounding for a tread portion.

Abstract: A rubber composition comprising as a rubber component a specified styrene-butadiene copolymer (A) and a styrene-isoprene copolymer of a specified hydrogenation ratio (B) wherein a bound styrene content of the copolymer (B) is larger by a given value than a bound styrene content of the copolymer (A) is good in the wear resistance and fracture property and further excellent in the wet-skid resistance and dry gripping property.

Abstract: A stabilized high-vinyl polybutadiene composition comprising a high-vinyl polybutadiene, and an antioxidant defined by the formula where each R1 and R2, which may be the same or different, are mono-valent organic groups, or where each R1, which may be the same or different, is a mono-valent organic group and the two R2 groups join to form a divalent organic group.