A cross-linked rubber obtained by cross-linking a nitrile rubber composition, wherein the nitrile rubber composition contains a carboxyl group-containing nitrile rubber (a) with an iodine value of 120 or less and a diurethane compound (b) represented by a following general formula (1), a content of the diurethane compound (b) in the nitrile rubber composition is 5 to 15 parts by weight with respect to 100 parts by weight of the carboxyl group-containing nitrile rubber (a), and a tensile strength of the cross-linked rubber based on JIS K6251 is 15 MPa or more and an elongation at break of the cross-linked rubber based on JIS K6251 is 300% or more, is provided.

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Provided are a rubber composition having a good balance of improved fuel efficiency, abrasion resistance, and wet grip performance while providing good processability, and a pneumatic tire having a tread manufactured from the rubber composition. A rubber composition comprising: a copolymer synthesized by copolymerization of a conjugated diene monomer and an unsaturated acyclic monoester represented by the formula (1) below; and carbon black and/or silica, ##STR00001##
wherein R.sup.1 represents hydrogen or a C1-C30 hydrocarbon group, and R.sup.2 represents hydrogen or a C1-C30 hydrocarbon group.

The present invention relates to a modified conjugated diene-based polymer having excellent processability and good tensile strength and viscoelasticity, and a rubber composition including the same, and provides a modified conjugated diene-based polymer including a first chain including a repeating unit derived from a conjugated diene-based monomer; a second chain including a repeating unit derived from a compound represented by Formula 1; and a derived unit from an alkoxysilane-based modifier, wherein the first chain and the second chain are coupled by the derived unit from the modifier.

The present invention relates to a modified conjugated diene-based polymer having excellent processability and good tensile strength and viscoelasticity, and a rubber composition including the same, and provides a modified conjugated diene-based polymer including a first chain including a repeating unit derived from a conjugated diene-based monomer; a second chain including a repeating unit derived from a compound represented by Formula 1; and a derived unit from an alkoxysilane-based modifier, wherein the first chain and the second chain are coupled by the derived unit from the modifier.

A depolymerizer is formed by grafting thiol groups on parts of the double bonds of a polymer of linear conjugated diene monomer. The linear conjugated diene monomer can be 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-phenyl-1,3-butadiene, or 4,5-diethyl-1,3-octadiene. The depolymerizer has a weight average molecular weight of 1000 to 400000.

A depolymerizer is formed by grafting thiol groups on parts of the double bonds of a polymer of linear conjugated diene monomer. The linear conjugated diene monomer can be 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-phenyl-1,3-butadiene, or 4,5-diethyl-1,3-octadiene. The depolymerizer has a weight average molecular weight of 1000 to 400000.

A modified conjugated diene-based polymer, a rubber composition including the same, and a method of making the same are disclosed herein. The modified conjugated diene-based polymer has excellent processability and good tensile strength and viscoelasticity. In some embodiments, a modified conjugated diene-based polymer includes a first chain including a repeating unit derived from a conjugated diene-based monomer, a second chain including a repeating unit derived from a compound represented by Formula 1, and a derived unit from an alkoxysilane-based modifier, wherein the first chain and the second chain are coupled by the derived unit from the alkoxysilane-based modifier.

A modified conjugated diene-based polymer, a rubber composition including the same, and a method of making the same are disclosed herein. The modified conjugated diene-based polymer has excellent processability and good tensile strength and viscoelasticity. In some embodiments, a modified conjugated diene-based polymer includes a first chain including a repeating unit derived from a conjugated diene-based monomer, a second chain including a repeating unit derived from a compound represented by Formula 1, and a derived unit from an alkoxysilane-based modifier, wherein the first chain and the second chain are coupled by the derived unit from the alkoxysilane-based modifier.

A nitrile group-containing copolymer rubber including 10 to 60 wt % of an α,β-ethylenically unsaturated nitrile monomer unit a nd 1 to 60 wt % of an α,β-ethylenically unsaturated dicarboxylic a cid monoester monomer unit, and having an iodine value of 120 or 1 ess, wherein a processability index Ipro (Ipro=CC×SA) is 0.003 0 or less, where the processability index Ipro is the product of the carboxyl group content CC, which is the number of moles of carboxyl groups per 100 g of nitrile group-containing copolymer rubber, and the absorbance area SA of a carboxylic anhydride group determined by infrared spectroscopy.

A nitrile group-containing copolymer rubber including 10 to 60 wt % of an α,β-ethylenically unsaturated nitrile monomer unit a nd 1 to 60 wt % of an α,β-ethylenically unsaturated dicarboxylic a cid monoester monomer unit, and having an iodine value of 120 or 1 ess, wherein a processability index Ipro (Ipro=CC×SA) is 0.003 0 or less, where the processability index Ipro is the product of the carboxyl group content CC, which is the number of moles of carboxyl groups per 100 g of nitrile group-containing copolymer rubber, and the absorbance area SA of a carboxylic anhydride group determined by infrared spectroscopy.