| abstract |
A conjugated diolefin copolymer rubber and a rubber composition which can produce vulcanized products exhibiting well-balanced improved properties such as wet skid properties, low hysteresis loss properties, abrasion resistance, and breaking strength irrespective of the types and combinations of fillers to be added, and is useful as a tread material for low fuel consumption tires, large tires, and high performance tires. A conjugated diolefin copolymer rubber is prepared by the copolymerization of a conjugated diolefin and a vinyl aromatic compound, and (1) has a content of the bonded vinyl aromatic compound of 5-50 wt %, (2) contains 0.01-5.0 mmol of an alkoxysilyl group having substantially non-hydrolyzable Si-O-R bond (wherein R indicates a hydrocarbon group having 4-20 carbon atoms) and 0.01-2.0 mmol of a tin-carbon bond for 100 g of the copolymer rubber, and (3) has a polymodal-type molecular weight distribution. |