Rubber composition

A method for producing a rubber composition having an improved abrasion resistance and tensile strength by controlling a molecular weight distribution of a rubber composition comprising (i) an incompatible polymer blend comprising at least two diene 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 incompatible 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 the block copolymer, of a 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, such that the polymers forming the polymer phases (A) and (B) satisfy the following equations (I) and (II):

• Mw30(A)/Mw(a)≦1.2 (I) Mw30(B)/Mw(b)≦1.2 (II)
• wherein
• Mw30(A):
• a value of molecular weight corresponding to 30% of the cumulative area when converting the curve of the distribution of the molecular weight measured by GPC to the integrated molecular weight curve of the polymer forming the polymer phase (A),
• Mw30(B):
• a value of molecular weight corresponding to 30% of the cumulative area when converting the curve of the distribution of the molecular weight measured by GPC to the integrated molecular weight curve of the polymer forming the polymer phase (B),
• 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.