The invention provides a heavy-duty tire rubber composition excellent in wet grip performance and steering stability, and a tire tread, a bead filler, a tire belt and a heavy-duty tire which each partially include the composition. The heavy-duty tire rubber composition includes 100 parts by mass of a solid rubber (A), 0.1 to 50 parts by mass of a modified liquid diene rubber (B) having a functional group derived from a silane compound with a specific structure, and 20 to 200 parts by mass of a filler (C), the modified liquid diene rubber (B) satisfying the following (i) and (ii): (i) the weight average molecular weight (Mw) is not less than 1,000 and not more than 120,000, and (ii) the vinyl content is not less than 30 mol % and less than 70 mol %.

The present invention is a modified resin for a molded article obtained by modifying an ethylene/unsaturated carboxylic acid copolymer with guanidine carbonate, wherein a melt flow rate of the ethylene/unsaturated carboxylic acid copolymer is 20 (g/10 minutes) or more and 600 (g/10 minutes) or less.

The present invention is a modified resin for a molded article obtained by modifying an ethylene/unsaturated carboxylic acid copolymer with guanidine carbonate, wherein a melt flow rate of the ethylene/unsaturated carboxylic acid copolymer is 20 (g/10 minutes) or more and 600 (g/10 minutes) or less.

Provided is a method for preparing a modified filler. The method includes in sequence providing an acidified aqueous slurry of an untreated inorganic filler which has not been previously dried; an emulsifier material; and a hydrophobating agent having the following structural formula (I):
R.sub.a.sup.−M-X.sub.(4−a)  (I)
wherein: R is C.sub.6 to C.sub.22 alkyl, M is silicon, titanium or zirconium, X is OR′ or halogen, R′ is C.sub.1 to C.sub.4 alkyl, and a is 1;
washing and/or filtering the acidified aqueous slurry to obtain a modified filler; and, optionally, drying the modified filler. Polymeric compositions and articles also are provided.

Provided is a method for preparing a modified filler. The method includes in sequence providing an acidified aqueous slurry of an untreated inorganic filler which has not been previously dried; an emulsifier material; and a hydrophobating agent having the following structural formula (I):
R.sub.a.sup.−M-X.sub.(4−a)  (I)
wherein: R is C.sub.6 to C.sub.22 alkyl, M is silicon, titanium or zirconium, X is OR′ or halogen, R′ is C.sub.1 to C.sub.4 alkyl, and a is 1;
washing and/or filtering the acidified aqueous slurry to obtain a modified filler; and, optionally, drying the modified filler. Polymeric compositions and articles also are provided.

Provided is a curing catalyst having a high safety and a practical curing rate.

According to the present invention, provided is a curing catalyst [B] used for curing a polymer [A] having a reactive hydrolyzable silicon-containing group, wherein the curing catalyst [B] contains a complex of a titanium compound [B1] and an ammonium hydroxide [B2], and an amine compound [B3], the titanium compound [B1] is represented by Chemical Formula (1), the ammonium hydroxide [B2] is represented by Chemical Formula (2), and the amine compound [B3] is represented by Chemical Formula (3), Chemical Formula (4), or Chemical Formula (5).

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.