Abstract: An object of the present invention is to provide a rubber composition which not only realizes sufficiently low heat generation properties but also exhibits more excellent crack growth resistance than the conventional rubber composition. The rubber composition contains in 100 mass % of rubber components thereof: 20-80 mass % of natural rubber in which the total nitrogen content in natural rubber latex is in the range of 0.1 mass % to 0.4 mass % (exclusive of 0.1 mass % and inclusive of 0.4 mass %); and butadiene-based polymer having cis content of 90% or higher.

Abstract: This invention relates to a rubber composition being excellent in the low heat buildup and fracture properties (resistance to crack growth). and more particularly to a rubber composition, characterized by compounding 10-100 parts by mass of an inorganic filler and/or carbon black based on 100 parts by mass of a rubber component including not less than 10 mass % of a modified conjugated diene-based polymer having a cis-1,4 bond content of not less than 90% and a vinyl bond content of not more than 1.2% and a primary amino group. In this case, the modified conjugated diene-based polymer is obtained by (1) reacting the predetermined conjugated diene-based polymer having an active terminal with a compound having two or more predetermined functional groups and (2) further reacting the resulting product with a compound having a primary amino group.

Abstract: A process for producing a modified conjugated diene-based copolymer comprising bringing a modifier into reaction with the active end of a copolymer of a conjugated diene compound and an aromatic vinyl compound having the active end, wherein a compound having (i) a hydrolyzable functional group having silicon and (ii) a group which can be converted into a protonic amino group or a protonic amino group protected with an eliminable functional group after the reaction is used as the modifier, a step of adding a condensation catalyst is conducted after the modifier is brought into the reaction, and the content of the unit of the aromatic vinyl compound and the structure of the chain of the aromatic vinyl compound are specified.

Abstract: The present invention provides a modified conjugated diene polymer that is prepared by polymerization of a conjugated diene compound using a catalyst containing a lanthanoid rare earth element compound in an organic solvent and then modifying the resulting polymer having an active organic metal site with a modifier, wherein the modification efficiency is not less than 15% and the cis-1,4 bond content in the conjugated diene moiety measured by Fourier transform infrared spectroscopy satisfies the relationship (I): cis-1,4 bond content?98.00(%)??(I), or the modification efficiency is not less than 75% and the cis-1,4 bond content in the conjugated diene moiety measured by Fourier transform infrared spectroscopy satisfies the relationship (II): 94.00(%)?cis-1,4 bond content<98.00(%)??(II).

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 an aromatic vinyl compound-conjugated diene compound copolymer capable of giving excellent wear resistance and resistance to wet skid to a tire, and more particularly to an aromatic vinyl compound-conjugated diene compound copolymer obtained by an addition polymerization of an aromatic vinyl compound and a conjugated diene compound in the presence of a polymerization catalyst composition comprising at least one specified metallocene complex selected from the group consisting of a metallocene complex represented by the following general formula (I): (wherein M is a lanthanoid element, scandium or yttrium, and CpR is independently a non-substituted or substituted indenyl, and Ra to Rf are independently an alkyl group having a carbon number of 1-3 or a hydrogen atom, and L is a neutral Lewis base, and w is an integer of 0-3) and so on, wherein a content of cis-1,4 bond in a conjugated diene compound portion is not less than 80%.

Abstract: This invention provides a polybutadiene capable of improving wear resistance and resistance to crack growth in a rubber composition and a tire, wherein values of e, f and g derived from the following determinant (I): ( 1.7455 0 - 0.0151 - 0.0454 0.4292 - 0.0129 - 0.007 0 0.3746 ) ? ( log 10 ? ( a / d ) log 10 ? ( a / b ) log 10 ? ( a / c ) ) = ( e f g ) ( I ) (wherein a is a mountain peak value around 1130 cm?1 in a transmittance spectrum through Fourier transform infrared spectroscopy (FT-IR), and b is a valley peak value around 967 cm?1, and c is a valley peak value around 911 cm?1, and d is a valley peak value around 736 cm?1) satisfy relationships of equation (II): (Calculated value of cis-1,4 bond)=e/(e+f+g)×100?99 and equation (III): (Calculated value of vinyl bond)=g/(e+f+g)×100?0.

Abstract: There is provided a method of producing a rare earth salt of a dialkyl phosphate or a rare earth salt of dioleyl phosphate of a high purity useful as a polymerization catalyst of a conjugated diene compound by directly reacting a rare earth oxide or a rare earth hydroxide with a dialkyl phosphate or dioleyl phosphate of a high purity. In the invention, the rare earth oxide or rare earth hydroxide is reacted with the dialkyl phosphate or dioleyl phosphate of a high purity in a non-polar solvent in the presence of at least one compound selected from a halogenated hydroacid, phosphorous acid and a rare earth halide made from the same element as in an objective product as a catalyst.

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, the method comprising the steps of preparing a reactive polymer, and reacting the reactive polymer with a halosilane compound containing an amino group.

Abstract: A functionalized polymer includes a polymer chain and a terminal functionality that includes at least one disilylamino group. The polymer can be the reaction product of a terminally active polymer chain and a compound that includes at least one disilylamino group and a group capable of reacting with terminally active polymers. Methods for making and using such polymers also are provided, as are compositions containing the polymer and one or more types of filler particles as well as vulcanizates provided from such compositions.

Abstract: There is provided a method of producing a rare earth salt of a dialkyl phosphate or a rare earth salt of dioleyl phosphate of a high purity useful as a polymerization catalyst of a conjugated diene compound by directly reacting a rare earth oxide or a rare earth hydroxide with a dialkyl phosphate or dioleyl phosphate of a high purity. In the invention, the rare earth oxide or rare earth hydroxide is reacted with the dialkyl phosphate or dioleyl phosphate of a high purity in a non-polar solvent in the presence of at least one compound selected from a halogenated hydroacid, phosphorous acid and a rare earth halide made from the same element as in an objective product as a catalyst.

Abstract: There are provided a rubber composition simultaneously improving low loss factor and wear resistance as compared with the conventional ones as well as a tire using such a rubber composition. The invention lies in a rubber composition using a modified conjugated diene rubber and being excellent in the low loss factor and wear resistance as well as a tire. The rubber composition of the invention is formed by compounding a filler to a rubber component containing (A) a modified conjugated diene rubber having a cis-bond content in conjugated diene portion of not less than 87% and a vinyl bond content of not more than 2% and containing a functional group reactive with a filler and (B) a modified polymer having a modifying functional group number per 1 molecule of an unmodified polymer of not less than 0.6.

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 flower-like nano-particle composition including a poly(alkenylbenzene) core and a poly(conjugated diene) or a poly(alkylene) surface layer is provided. The nano-particles have a mean average diameter less than about 100 nm and are substantially free of chain ends. The nano-particles can be modified via, for example, hydrogenation. The nano-particles can advantageously be incorporated into rubbers, elastomers, and thermoplastics.

Abstract: This invention relates to a novel polymerization initiator capable of introducing an active amino proton into a polymerization starting terminal without losing polymerization activity, and a novel modified conjugated diene polymer being excellent in the interaction with a filler and capable of improving a low heat buildup of a rubber composition, and more particularly to a polymerization initiator being a diamine compound in which one amino group is protected with a silylating agent and an active proton of the other amino group is replaced with an alkali metal or an alkaline earth metal, and a modified conjugated diene polymer which can be produced by using such a polymerization initiator and is a homopolymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound and has a residue derived from a diamine compound at its polymerization starting terminal.

Abstract: This invention provides a polybutadiene capable of improving wear resistance and resistance to crack growth in a rubber composition and a tire, wherein values of e, f and g derived from the following determinant (I): ( 1.7455 0 - 0.0151 - 0.0454 0.4292 - 0.0129 - 0.007 0 0.3746 ) ? ( log 10 ? ( a / d ) log 10 ? ( a / b ) log 10 ? ( a / c ) ) = ( e f g ) ( I ) (wherein a is a mountain peak value around 1130 cm?1 in a transmittance spectrum through Fourier transform infrared spectroscopy (FT-IR), and b is a valley peak value around 967 cm?1, and c is a valley peak value around 911 cm?1, and d is a valley peak value around 736 cm?1) satisfy relationships of equation (II): (Calculated value of cis-1,4 bond)=e/(e+f+g)×100?99 and equation (III): (Calculated value of vinyl bond)=g/(e+f+g)×100?0.

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: This invention relates to a rubber composition having a high interaction between rubber component and carbon black, a good wear resistance and an excellent low heat buildup (low hysteresis loss), and more particularly to a rubber composition comprising (A) 100 parts by mass of a rubber component containing not less than 10% by mass of a conjugated diene polymer having a polymer chain with at least one functional group selected from the group consisting of particular substituted amino group and cyclic amino group, (B) not less than 20 parts by mass of carbon black and (C) not more than 1.0 part by mass of a polycyclic aromatic compound (PCA).

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.