Provided is a rubber composition having excellent adhesiveness to a metal member even if no cobalt salt is contained. The rubber composition contains a rubber component, a rubber-metal adhesion promoter containing Bi, and an organic acid salt of metal other than Bi, where a content of metal element other than Bi with respect to a content of Bi element (content of metal element other than Bi/content of Bi element) in the rubber composition is more than 14 and 100 or less in terms of molar ratio, a content of the rubber-metal adhesion promoter is more than 1.5 parts by mass with respect to 100 parts by mass of the rubber component, and the amount of substance of metal element other than Bi contained in the organic acid salt of metal other than Bi in the rubber composition is 0.01 mol or more.

A rubber composition that includes a rubber component, an inorganic fiber material, and a coupling agent. The inorganic fiber material is one or more inorganic fiber materials selected from the group consisting of a magnesium sulfate fiber, a calcium silicate fiber, a potassium titanate fiber, an aluminum borate fiber, and a glass fiber.

A rubber composition that includes a rubber component, an inorganic fiber material, and a coupling agent. The inorganic fiber material is one or more inorganic fiber materials selected from the group consisting of a magnesium sulfate fiber, a calcium silicate fiber, a potassium titanate fiber, an aluminum borate fiber, and a glass fiber.

The present invention relates to a hydrous silica for rubber reinforcing fillers having CTAB specific surface area in the range of 220 to 350 m.sup.2/g and a pore volume over the range of pore radius 1.9 to 100 nm measured by mercury press-in method in the range of 1.7 to 2.0 cm.sup.3/g, wherein a volume average particle diameter D50 in a volume particle size distribution measured by laser diffraction method for the slurry obtained by dispersing 50 ml of a hydrous silica slurry adjusted to 4 mass % with an ultrasonic homogenizer at an output of 140 W for 10 minutes is in the range of 5.0 to 12.0 μm, and a cumulative value of hydrous silica particles over the range of 4.0 to 35.0 μm in the volume particle size distribution is 80% or more. The present invention also relates to a rubber composition containing the above-mentioned hydrous silica and a rubber component containing a natural rubber. The present invention provides a hydrous silica which has equivalent or excellent reinforcing property (abrasion resistance, tensile strength) and which allows to greatly reduce the rolling resistance when it is blended into a rubber based on the natural rubber for TBRs, which is often used under a heavy load, compared with conventional hydrous silicas, and provides the rubber composition containing the hydrous silica.

The present invention relates to a hydrous silica for rubber reinforcing fillers having CTAB specific surface area in the range of 220 to 350 m.sup.2/g and a pore volume over the range of pore radius 1.9 to 100 nm measured by mercury press-in method in the range of 1.7 to 2.0 cm.sup.3/g, wherein a volume average particle diameter D50 in a volume particle size distribution measured by laser diffraction method for the slurry obtained by dispersing 50 ml of a hydrous silica slurry adjusted to 4 mass % with an ultrasonic homogenizer at an output of 140 W for 10 minutes is in the range of 5.0 to 12.0 μm, and a cumulative value of hydrous silica particles over the range of 4.0 to 35.0 μm in the volume particle size distribution is 80% or more. The present invention also relates to a rubber composition containing the above-mentioned hydrous silica and a rubber component containing a natural rubber. The present invention provides a hydrous silica which has equivalent or excellent reinforcing property (abrasion resistance, tensile strength) and which allows to greatly reduce the rolling resistance when it is blended into a rubber based on the natural rubber for TBRs, which is often used under a heavy load, compared with conventional hydrous silicas, and provides the rubber composition containing the hydrous silica.

In a first aspect, the present invention is directed to a rubber composition comprising 70 phr to 90 phr of styrene butadiene rubber, wherein said styrene butadiene rubber comprises a first styrene butadiene rubber having a glass transition temperature within a range of −49° C. to −15° C. and a second styrene butadiene rubber having a glass transition temperature within a range of −50° C. to −89° C. Furthermore, the rubber composition comprises from 10 phr to 30 phr of one or more of natural rubber and synthetic polyisoprene rubber, 100 phr to 200 phr of silica, and at least 25 phr of at least one terpene resin having a weight average molecular weight (Mw) of at most 1000 g/mol. Moreover, the invention is directed to a tire comprising such a rubber composition, in particular in the tread of the tire.

In a first aspect, the present invention is directed to a rubber composition comprising 70 phr to 90 phr of styrene butadiene rubber, wherein said styrene butadiene rubber comprises a first styrene butadiene rubber having a glass transition temperature within a range of −49° C. to −15° C. and a second styrene butadiene rubber having a glass transition temperature within a range of −50° C. to −89° C. Furthermore, the rubber composition comprises from 10 phr to 30 phr of one or more of natural rubber and synthetic polyisoprene rubber, 100 phr to 200 phr of silica, and at least 25 phr of at least one terpene resin having a weight average molecular weight (Mw) of at most 1000 g/mol. Moreover, the invention is directed to a tire comprising such a rubber composition, in particular in the tread of the tire.

A rubber composition, which exhibits an improved fatigue strength and stiffness performance compromise, is based on at least one elastomer matrix containing at least one polyisoprene and at least one copolymer containing ethylene units and diene units; a paraffin oil having a glass transition temperature of less than -75° C.; a reinforcing filler comprising carbon black; and a crosslinking system, in which the at least one polyisoprene and the at least one copolymer containing ethylene units and diene units represent more than 40% by weight of the elastomer matrix.

A rubber composition, which exhibits an improved fatigue strength and stiffness performance compromise, is based on at least one elastomer matrix containing at least one polyisoprene and at least one copolymer containing ethylene units and diene units; a paraffin oil having a glass transition temperature of less than -75° C.; a reinforcing filler comprising carbon black; and a crosslinking system, in which the at least one polyisoprene and the at least one copolymer containing ethylene units and diene units represent more than 40% by weight of the elastomer matrix.

The invention relates to a process which responds to this problem scenario. The invention therefore relates to a process for preparing a rubber composition based on at least one diene elastomer, a reinforcing filler, a crumb rubber and a crosslinking system, said process comprising at least the following steps: incorporating the reinforcing filler into the diene elastomer, all at once or in several stages, and mixing; when the temperature of the mixture reaches a temperature of greater than 100° C., adding the crumb rubber; continuing the mixing up to a maximum temperature of between 120° C. and 190° C.; cooling the mixture to a temperature of less than 100° C.; incorporating the crosslinking system and mixing up to a maximum temperature of less than 110° C.