Abstract: The rubber composition of the present invention comprises a rubber component which is a blend rubber of a copolymer rubber and other diene based rubbers or the copolymer rubber alone, the copolymer rubber having a glass transition temperature of −60° C.

Abstract: A rubber composition prepared by blending 15 to 85 parts by weight of silica per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber and 1 to 15% by weight of a dispersion-improving agent based on the amount of the silica described above. Further, a rubber composition prepared by blending 20 to 60 parts by weight of silica and 30 to 80 parts by weight of carbon black having a cetyl trimethylammonium bromide-adsorbing amount (CTAB) of 120 m2/g or more and a dibutyl phthalate-absorbing amount (DBP) of 120 ml/100 g or more per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber, and 3 to 15% by weight of a dispersion-improving agent based on the amount of the silica described above, wherein the total amount of silica and carbon black is 50 to 120 parts by weight. A specific nitrogen-containing carbonyl compound or silicone oil is used as a dispersion-improving agent.

Abstract: The present invention provides a rubber composition and a pneumatic tire using the rubber composition. A rubber composition comprises silica in an amount of 10 to 85 parts by weight per 100 parts by weight of natural rubber and/or diene synthetic rubbers. A polysulfide silane coupling agent having a specific distribution of sulfur reacts with a trivalent phosphorus compound such that a content of high polysulfide in the polysulfide silane coupling agent is reduced. The rubber composition further comprises 1 to 20% by weight, based on an amount of the silica, of the polysulfide silane coupling agent having a specific distribution of sulfur such that a content of high polysulfide component is small. The pneumatic tire has an excellent low heat buildup property.

Abstract: The present invention provides a rubber composition and a pneumatic tire using the rubber composition. The rubber composition which comprises: a rubber component comprising a styrene-butadiene copolymer rubber or a blend of the styrene-butadiene copolymer rubber and another conjugated diene base rubber with the styrene-butadiene copolymer rubber being 70% by weight or more of the entire blend, and the entire content of styrene is 30 to 40% by weight of the entire rubber component; silica in an amount of 10 to 60 parts by weight per 100 parts by weight of the rubber component; a specific silane coupling agent, i.e., a bis(alkoxysilylalkyl)polysulfide having a polysulfide chain in which the distribution of sulfur is specified, in an amount of 1 to 20% by weight of the amount of silica; and carbon black, the sum of the amount of silica and carbon black being 60 to 130 parts by weight per 100 parts by weight of the rubber component.

Abstract: The present invention provides a rubber composition and a pneumatic tire using the rubber composition. The rubber composition comprises a diene base rubber comprising at least 15% by weight of a polybutadiene rubber, silica in an amount of 10 to 80 parts by weight per 100 parts by weight of the diene base rubber and, in an amount of 1 to 20% by weight of the amount of silica, a specific silane coupling agent, i.e., a bis (alkoxysilylalkyl) polysulfide having a polysulfide chain in which the distribution of sulfur is specified. After curing, the cured rubber composition includes closed cells. Therefore, the rubber composition has a good processability at the time of manufacturing of a tire and a pneumatic tire using the same has excellent snow/ice grip performance and abrasion resistance.

Abstract: A pneumatic tire having improved rolling resistance and wear resistance comprises a tread made from a rubber composition containing a partially hydrophobizated silica subjected to a surface treatment with an organosilicon compound so as to have specified hydrophobization ratio and apparent density.

Abstract: A rubber composition which comprises natural rubber and diene synthetic rubbers and carbon black having a cetyltrimethylammonium bromide surface area, a dibutyl phthalate absorption amount, a most frequent value of aggregate diameter distribution, a ratio of a half value width of aggregate diameter distribution to a most frequent value of aggregate diameter distribution, a ratio of a nitrogen adsorption specific surface area to an iodine adsorption amount, and a ratio of a cetyltrimethylammonium bromide surface area to an iodine adsorption amount in respective specific ranges, and a pneumatic tire prepared by using the rubber composition for a tread. The rubber composition and the pneumatic tire are excellent in all of abrasion resistance, resistance to tearing, and low heat buildup.

Abstract: The present invention provides a rubber composition comprising natural rubber and/or diene synthetic rubbers, silica in an amount of 10 to 85 parts by weight per 100 parts by weight of the rubber, a specific silane coupling agent, i.e., a bis-(alkoxysilylalkyl) polysulfide having a polysulfide structure in which the distribution of sulfur is specified, in an amount of 1 to 20% by weight of the amount of silica, and provides a pneumatic tire manufactured by using the rubber composition. The pneumatic tire has excellent low heat buildup property, low rolling resistance, and reinforcing property.

Abstract: The present invention provides a rubber composition comprising natural rubber and/or diene synthetic rubbers, silica in an amount of 10 to 85 parts by weight per 100 parts by weight of the rubber, a specific silane coupling agent, i.e., a bis(alkoxysilylalkyl) polysulfide having a polysulfide structure in which the distribution of sulfur is specified, in an amount of 1 to 20% by weight of the amount of silica, and a specific silica dispersion improver in an amount of 1 to 15% by weight of the amount of silica, and provides a pneumatic tire manufactured by using the rubber composition. The pneumatic tire has excellent low heat buildup property and abrasion resistance.

Abstract: Rubber compositions and pneumatic tires in which the rubber compositions are used. In the rubber compositions, per 100 parts by weight of natural rubber and a conjugated diene-base synthetic rubber such as a butadiene-styrene copolymer rubber, is compounded 30 to 120 parts by weight of a carbon black having both a characteristic (concentration of >C.dbd.O functional groups)/N.sub.2 SA.gtoreq.4.0.times.10.sup.-4 and a characteristic (concentration of >C.dbd.O functional groups).gtoreq.(concentration of --OH functional groups).sup.2 -0.1.times.(concentration of --OH functional groups)+0.03, or is compounded 30 to 120 parts by weight of a carbon black having the characteristic (concentration of >C.dbd.O functional groups)/N.sub.2 SA.gtoreq.4.0.times.10.sup.-4 and 0.05 to 5.0 parts by weight of at least one of a silane coupling agent, a hydrazide compound and a thiadiazole compound.

Abstract: The wear resistance of the pneumatic tire used under a high severity region is improved by using a particular high-trans polybutadiene rubber in a rubber composition for a ground contact part of the tire tread.