Patent ID: 6927255

Claim:
A rubber composition comprising (i) an incompatible polymer blend comprising at least two diene-based rubbers selected from the group consisting of rubbers containing at least one conjugated diene monomer and, optionally, at least one aromatic vinyl monomer and forming two polymer phases (A) and (B) and (ii) 0.1 to 20 parts by weight, based upon 100 parts by weight of the total polymer component including a block copolymer, of the block copolymer having at least two mutually incompatible blocks (a) and (b), in which the block (a) is compatible with the polymer phase (A) and incompatible with the polymer phase (B) and the block (b) is compatible with the polymer phase (B) and incompatible with the polymer phase (A), and comprising at least one conjugated diene monomer and, optionally, at least one aromatic vinyl monomer and (iii) 5 to 200 parts by weight, based upon 100 parts by weight of the block copolymer, of a polymer (α) compatible with the block (a) and the polymer phase (A), a polymer (β) compatible with the block (b) and polymer phase (B) and a mixture of the polymer (α) and the polymer (β), wherein the weight average molecular weights of the polymers (α) and (β) satisfy the following equations (III) and (IV): Mw (α)/ Mw ( a )≦1.2 (III) Mw (β)/ Mw ( b )≦1.2 (IV) wherein Mw(α): weight average molecular weight of polymer (α), Mw(β) weight average molecular weight of polymer (β), Mw(a): weight average molecular weight of block (a) of block copolymer, and Mw(b): weight average molecular weight of block (b) of block copolymer.