Processes for producing wet rubber masterbatch and rubber composition

A process for producing a rubber composition comprising a wet rubber masterbatch yielded by using, as raw materials, at least a filler, a dispersing solvent, and a rubber latex solution, wherein the process comprises:

• a step (i) of mixing the filler, the dispersing solvent, and the rubber latex solution with each other to produce a filler-containing rubber latex solution, a step (ii) of solidifying the filler-containing rubber latex solution to produce a filler-containing rubber solidified product, a step (iii) of dehydrating the filler-containing rubber solidified product to produce the wet rubber masterbatch, and a step (iv) of dry-mixing the wet rubber masterbatch with various blending agents to produce the rubber composition,
• wherein at the time of representing the temperature of the filler-containing rubber solidified product before the dehydration in the step (iii) by T1 (° C.), and representing the temperature of the filler-containing rubber solidified product after the dehydration by T2 (° C.), the following expressions (1) and (2) are satisfied:
• T1≤100 (1)
• 80≤T2−T1≤160 (2),
• wherein the step (iii) is a step of using a monoaxial extruder or a biaxial extruder to dehydrate the filler-containing rubber solidified product, and the rotation number R (rpm) of a screw of the monoaxial extruder or the biaxial extruder satisfies the following:
• 2≤R≤35.