Method for manufacturing wet rubber masterbatch

1. A method for manufacturing wet rubber masterbatch obtained from raw materials in the form of at least filler, dispersion solvent, and rubber latex solution, the method for manufacturing wet rubber masterbatch comprising:

an operation in which the rubber latex solution is mixed and coagulated with a slurry solution containing the filler and the dispersion solvent to manufacture a filler-containing rubber coagulum; and

a heating operation in which a single-screw extruder is used to carry out dewatering, drying, and plasticization of the filler-containing rubber coagulum in a single operation;

wherein the single-screw extruder has a dewatering portion toward a side thereof from which the filler-containing rubber coagulum is fed, a drying portion toward a side thereof from which the filler-containing rubber coagulum is discharged, and a screw that passes through said dewatering portion and said drying portion;

wherein the screw has a plurality of peaks and a plurality of troughs;

wherein the dewatering portion has an inside wall that faces the screw, and is equipped with a barrel that houses the screw;

wherein the method for manufacturing wet rubber masterbatch is characterized in that it satisfies conditions indicated by General Formula (1);

wherein General Formula (1) is 0.02≤C/(A×B)≤0.15;

wherein A indicates, for a portion of the screw which is located at the dewatering portion, the pitch volume in units of mm 3 which is the volume swept by a region corresponding to one pitch length from the downstream-most peak in the direction in which the filler-containing rubber coagulum is extruded to the peak that is adjacent to said downstream-most peak, and the clearance from the base of the trough of the screw which is present at said region corresponding to one pitch length to the inside wall of the barrel, during one rotation of the screw;

wherein B indicates rotational speed in units of rpm of the screw; and

wherein C indicates feed volume per minute in units of mm 3 /min of the filler-containing rubber coagulum which is fed into the single-screw extruder,

wherein temperature of the filler-containing rubber coagulum immediately before it is extruded from the dewatering portion to the drying portion is not less than 50° C. but is not greater than 110° C.