PURPOSE:To obtain a titled rubber compsn. having high repulsion modulas, by a method wherein in a process for the production of a rubber compsn. for tire tread comprising blending carbon black with a rubber raw material consisting of an amorphous polybutadiene having a high 1,2-bond unit contact and natural rubber and/or a polyisoprene; in the first kneading stage sulfur and carbon black are previously kneaded with part of the rubber raw material, and in the second kneading stage an additional amount of the rubber raw material is added to the mixt. from the first stage. CONSTITUTION:In a process for the production of a rubber compsn. for tire tread comprising blending carbon black with a rubber raw matrial consisting of 25-75wt% amorphous polybutadiene having a 1,2-bond unit content of 65-90mol% and a Mooney viscosity (ML1+4, 100 deg.C) of 20-100 and 75-25wt% natural rubber and/or a polyisoprene rubber; sulfur and 40-70pts.wt. carbon black are previously added to 40-60pts.wt. rubber raw material (but contg. not more than 25wt% natural rubber and/or cis-1,4-polyisoprene) and the mixt. is kneaded. Then to the mixt. is added an additional amount of the rubber raw material in such a proportion as to give 40-70pts.wt. carbon black per 100pts.wt. of rubber raw material [consisting of 25- 75wt% of amorphous polybutadiene and 75-25wt% natural rubber and/or polyisoprene rubber). The esulting mixt. is kneaded to obtain the desired rubber compsn. for tire tread, which has improved rolling resistance and wet skid resistnace.
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