Abstract: A process for preparing a copolymer of an acyclic conjugated diene and a cyclic conjugated diene using a polymerization catalyst system comprising a transition metal compound or a lanthanide metal compound, an alkylating agent, and an inorganic halide alcoholate, and rubber compositions and tires comprising the same. The copolymer contains at least 90% acyclic conjugated diene monomer, has a number average molecular weight of between 40,000 and 300,000, and has a cis-bond content of at least 92%.

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: The present invention provides a modified polymer, which is obtained by reacting, with an active metal bonded to a polymer, a modifier represented by the general formula (I) (where X1 to X5 each represent a hydrogen atom or a specific monovalent functional group, and at least one of those is other than a hydrogen atom, R1 to R5 each represent a single bond or a divalent hydrocarbon group having 1 to 18 carbon atoms, and a plurality of aziridine rings may be bonded through any of X1 to X5 and R1 to R5).

Abstract: A method for preparing a functionalized polymer, the method comprising the steps of (i) polymerizing conjugated diene monomer by employing a lanthanide-based catalyst to form a reactive polymer, and (ii) reacting the reactive polymer with a protected oxime compound.

Abstract: A method for preparing a functionalized polymer, the method comprising the steps of (i) polymerizing monomer with a coordination catalyst to form a reactive polymer; and (ii) reacting the reactive polymer with a nitrile compound containing a protected amino group.

Abstract: A method for preparing a functionalized polymer, the method comprising the steps of (i) polymerizing conjugated diene monomer by employing a lanthanide-based catalyst to form a reactive polymer, and (ii) reacting the reactive polymer with a protected oxime compound.

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: A method for preparing a functionalized polymer, the method comprising the steps of (i) polymerizing conjugated diene monomer by employing a lanthanide-based catalyst to form a reactive polymer, and (ii) reacting the reactive polymer with an azine compound.

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 is concerned with a butadiene-based polymer having a high cis-1,4 bond content, a low vinyl bond content and a molecular weight distribution of a specified range, and more particularly a butadiene-based polymer having a 1,3-butadiene monomer unit, characterized in that a cis-1,4 bond content and a vinyl bond content in the 1,3-butadiene monomer unit as measured by a Fourier transform infrared spectroscopy (FT-IR) is not less than 98.0% and not more than 0.3%, respectively, and a ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) is 1.6-3.5.

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 present invention provides a rubber composition containing a rubber component (A) including a modified polymer having a protic amine structure, and an oxidizing agent (B), in which interaction between the rubber component and a carbon black is excellent and dispersibility of the carbon black is improved. This rubber composition enables to obtain a tire that is excellent in low heat generation, rupture property, and abrasion resistance and the like. Also provided are a method of efficiently producing such a rubber composition and a tire having the above-mentioned characteristics which is made of the rubber composition.

Abstract: The invention relates to a pneumatic tire having excellent mechanical properties by using a rubber composition containing a polybutadiene rubber having a high cis-1,4 bond content, a low vinyl bond content and proper number average molecular weight and molecular weight distribution, and more particularly to a pneumatic tire characterized in that a rubber composition including a polybutadiene with a cis-1,4 bond content of not less than 99.0% and a vinyl bond content of not more than 0.3% as measured by a Fourier transform infrared spectroscopy is used in any one of tire members.

Abstract: This invention relates to a rubber composition including a polyisoprene rubber having a very high cis-1,4-bond content and having an excellent balance between dynamic properties and processability, and more particularly to a rubber composition comprising as a rubber component (A) a synthetic polyisoprene rubber having a cis-1,4-bond content of not less than 99.0%, a 3,4-bond content of not more than 0.5% and a Mooney viscosity ML1+4 (100° C.) of 20-110 and (B) a natural rubber.

Abstract: The present invention provides a modified polymer, which is obtained by reacting, with an active metal bonded to a polymer, a modifier represented by the general formula (I) (where X1 to X5 each represent a hydrogen atom or a specific monovalent functional group, and at least one of those is other than a hydrogen atom, R1 to R5 each represent a single bond or a divalent hydrocarbon group having 1 to 18 carbon atoms, and a plurality of aziridine rings may be bonded through any of X1 to X5 and R1 to R5).

Abstract: A method for preparing a functionalized polymer, the method comprising the steps of (i) polymerizing conjugated diene monomer by employing a lanthanide-based catalyst to form a reactive polymer, and (ii) reacting the reactive polymer with a protected oxime compound.

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 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: The invention relates to a pneumatic tire having excellent mechanical properties by using a rubber composition containing a polybutadiene rubber having a high cis-1,4 bond content, a low vinyl bond content and proper number average molecular weight and molecular weight distribution, and more particularly to a pneumatic tire characterized in that a rubber composition including a polybutadiene with a cis-1,4 bond content of not less than 99.0% and a vinyl bond content of not more than 0.3% as measured by a Fourier transform infrared spectroscopy is used in any one of tire members.

Abstract: A method for preparing a functionalized polymer, the method comprising the steps of (i) polymerizing conjugated diene monomer by employing a lanthanide-based catalyst to form a reactive polymer, and (ii) reacting the reactive polymer with an azine compound.