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.

Abstract: A stabilized high-vinyl polybutadiene composition comprising a high-vinyl polybutadiene, and an antioxidant defined by the formula 1

Abstract: A process for polymerizing 1,3-butadiene into a low molecular weight high-cis polybutadiene is described using a catalyst system comprising: (a) a neodymium-containing compound, (b) an aluminoxane or a trialkyl aluminum compound, (c) an organoaluminum hydride, and (d) a halogen source. A blend of a high molecular weight high-cis polybutadiene and the low molecular weight high-cis polybutadiene is also disclosed for use in pneumatic tire treads. Desirably both the high and the low molecular weight polymers have high cis contents, with the low molecular weight polymer being at least 70 percent cis and the high molecular weight polymer being at least 92 percent cis. Desirably both polymers are made with a neodymium catalyst system. The blends provide a balance of properties including good snow traction, wet traction, and rolling resistance while providing a balance of good physical properties including tension at break, modulus etc.

Abstract: A vulcanizate that has improved damping properties where the vulcanizate is prepared by the steps comprising blending an unsaturated damping additive within a vulcanizable composition of matter, wherein the vulcanizable composition of matter includes a vulcanizable elastomer, and effecting vulcanization of the elastomer.

Abstract: A rubber composition includes a rubber component and particulates of a crystalline syndiotactic-1,2-polybutadiene resin dispersed therein. The particulates have an average particle diameter of 1 to 500 .mu.m, and the melting point of the crystalline syndiotactic-1,2-polybutadiene resin is not less than 110.degree. C. The compounding ratio of the resin is 5 to 60 parts by weight relative to 100 parts by weight of the rubber component. The rubber composition is useful for tires, other rubber articles, etc. With respect to tires in particular, a pneumatic tire includes a rubber composition used for a tread, wherein the rubber composition includes a rubber component and particulates of crystalline syndiotactic-1,2-polybutadiene resin. The matrix portion of the tread rubber other than the above particulates is preferably a foamed rubber.

Abstract: A process for producing a diolefin polymer or copolymer, comprising the steps of polymerizing 55-100 wt % of a conjugated diolefin with 0-45 wt % of an aromatic vinyl compound as monomers in a hydrocarbon as a solvent, by using initiators: a reaction product [a1] between at least one secondary amine compound (A) and an organic lithium compound and/or a lithium amide compound [a2] of the at least one secondary amine compound (A) as well as a reaction product [b1] between at least one alcohol (B) and an organic lithium compound and/or a lithium alkoxide compound of the at least one alcohol (B). A rubber composition containing not less than 30 wt % of such a diolefin polymer or copolymer with respect to an entire rubber component is also disclosed. This rubber composition exhibits excellent abrasion resistance, high tensile strength, steering stability and low rolling resistance, and is suitable for tires, particularly, as treads of low fuel consumption tires.

Abstract: As a tread rubber of a pneumatic tire is used a rubber composition comprising 10-150 parts by weight of a silica filler, 0-150 parts by weight of carbon black and 0.2-10 parts by weight of at least one specified silane coupling agent, based on 100 parts by weight of a particular polymer rubber having a glass transition temperature of not lower than -50.degree. C. through polymerization of 1,3-butadiene or copolymerization of 1,3-butadiene and styrene with an organic alkali metal initiator, or a rubber blend of not less than 30 parts by weight of the above polymer and not more than 70 parts by weight of the other diene series rubber.

Abstract: A rubber composition satisfying wear resistance and fracture properties as well as wet skid resistance, ice skid resistance and dry gripping property is provided by including at least 30% by weight of a rubber ingredient which consists of 100 parts by weight of a particular branched styrene-butadiene copolymer (A) and 15-100 parts by weight of a particular low molecular weight butadiene polymer (B) and has a Mooney viscosity of 30-100.

Abstract: As a tread rubber of a pneumatic tire is used a rubber composition comprising 10-150 parts by weight of a silica filler, 0-150 parts by weight of carbon black and 0.2-10 parts by weight of at least one specified silane coupling agent, based on 100 parts by weight of a particular polymer rubber having a glass transition temperature of not lower than -50.degree. C. through polymerization of 1,3-butadiene or copolymerization of 1,3-butadiene and styrene with an organic alkali metal initiator, or a rubber blend of not less than 30 parts by weight of the above polymer and not more than 70 parts by weight of the other diene series rubber.

Abstract: There is a tire having tire performances such as wear resistance, cut resistance, heat build-up and the like and a processability simultaneously and economically improved by the application of a rubber composition containing a rubbery polymer modified with a silane compound and silica. The rubbery polymer modified with the silane compound is obtained by reacting an active terminal of a living polymer, which is obtained by polymerizing a monomer in the presence of an organic alkali metal catalyst, with a silane compound represented by the following general formula:X.sub.n Si(OR).sub.m R'.sub.4-m-n(where X is a halogen atom selected from a chlorine atom, a bromine atom and an iodine atom, OR is a non-hydrolyzable alkoxy group having a carbon number of 4.about.20, an aryloxy group or a cycloalkoxy group, R' is an alkyl group having a carbon number of 1.about.20, an aryl group, a vinyl group or a halogenated alkyl group, m is an integer of 1.about.4, n is an integer of 0.about.2, and a sum of n and m is 2.about.

Abstract: A rubber composition for tire having improved processability, wear resistance, rebound resilience and heat build-up comprises 20.about.70 parts by weight of a specified butadiene polymer, 30.about.80 parts by weight of at least one rubber selected from natural rubber, high cis-1,4 polyisoprene rubber and styrene-butadiene copolymer rubber, and 0.about.30 parts by weight of high cis-1,4 polybutadiene and/or low cis-1,4 polybutadiene, and contains 35.about.100 parts by weight of carbon black, 0.about.50 parts by weight of process oil, 0.5.about.5 parts by weight of aliphatic carboxylic acid and 0.1.about.3 parts by weight of sulfur based on 100 parts by weight of the above rubber components.

Abstract: A rubber composition is disclosed which contains not less than 20% by weight in a rubber component of a block copolymer composed of polymer or copolymer block units (A) and a random copolymer block units (B). The polymer or copolymer block units (A) are obtained by singly polymerizing a conjugated diolefine or copolymerizing the conjugated diolefine and a monovinyl aromatic hydrocarbon with use of a lithium initiator and contains not more than 10% by weight of the bound monovinyl aromatic hydrocarbon. The random copolymer block unit (B) are obtained by copolymerizing the conjugated diolefine and the monovinyl aromatic hydrocarbon and contain 15 to 80% by weight of the bound monovinyl aromatic hydrocarbon.

Abstract: A rubber composition comprising not less than 20% by weight of an amino group-containing diene based polymer in a rubber component, and 10 to 100 parts by weight of silica as a filler with respect to 100 parts by weight of the rubber component. The amino group-containing diene based polymer is obtained by polymerizing a monomer or copolymerizing the monomer in an organic solvent in the presence of at least one of an organic alkali metal and an organic alkaline earth metal.

Abstract: A conjugated diene series rubber composition comprises, as a rubber component, (a) 20.about.100% by weight of a particular conjugated diene polymer and (b) a diene polymer rubber except for the polymer (a) and is excellent in the processability at unvulcanized state and the rebound resilience, strengths at rupture and wear resistance at vulcanized state.

Abstract: A butadiene-based rubber composition is disclosed, which contains not less than 20% by weight of a butadiene-based homopolymer or copolymer having a glass transition temperature (Tg) of not less than -105.degree. C., but less than -70.degree. C. and a Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 10 to 150. The butadiene-based homopolymer or copolymer is obtained by polymerizing butadiene or random-copolymerizing butadiene with at least one kind of a monomer selected from the group consisting of another conjugated diene and an aromatic vinyl compound, and then reacting polymerization-active terminals thereof with an isocyanate compound and/or an isothiocyanate compound. The butadiene-based rubber composition has excellent resilience, fracture strength, and wear resistance as a vulcanizate as well as excellent processability as an unvulcanized rubber, and can be used as tire applications such as tire treads, undertreads, sidewalls, bead portions, etc.

Abstract: A rubber composition is disclosed which contains, as a rubber component, 20-100% by weight of (A) polybutadiene polymerized by using a lithium initiator and 80 to 0% by weight of (B) another rubber component. The polybutadiene has the following physical properties (i)-(v):(i) The molecular weight distribution of Mw/Mn is 1.4 to 3.0 in which Mw and Mn are a weight average molecular weight and a number average molecular weight, respectively;(ii) A polymer component having the molecular weight being not more than 10.sup.5 when calculated as polystyrene is from 7 to 25%;(iii) The content of bound vinyl groups is from 10 to 25%;(iv) The content of tin atoms bonded to the polymer by tin-carbon bonds is not less than 50 ppm;(v) Mooney viscosity (ML.sub.1+4, 100.degree. C.) is from 20 to 70.

Abstract: A rubber composition containing not less than 20% of a conjugated diene based polymer or copolymer. The polymer or copolymer is obtained by polymerizing a conjugated diene or copolymerizing the conjugated diene with at least one kind of other conjugated diene and an aromatic vinyl compound with use of a lithium initiator, and then reacting an isocyanate compound with active terminals of the thus obtained polymer or copolymer. The conjugated diene is butadiene or isoprene, while other conjugated diene is selected from pentadiene, 2,3-dimethylbutadiene as well as isoprene and butadiene, and an aromatic vinyl compound may be styrene, vinyltoluene, .alpha.-methylstyrene, etc. The rubber composition is applicable as tread portion, carcass, side wall portion of tires, vibration resistant rubber, window frame, hose, and various industrial articles.