A masterbatch manufacturing method in accordance with the present disclosure comprises an operation in which pre-coagulation rubber latex comprising filler is coagulated to obtain a coagulum; an operation in which the coagulum is dewatered; and an operation in which the dewatered coagulum is plasticized as it is dried by means of an extruder; wherein, during the operation in which the dewatered coagulum is plasticized as it is dried, the coagulum comprises a peptizing agent.

A masterbatch manufacturing method in accordance with the present disclosure comprises an operation in which pre-coagulation rubber latex comprising filler is coagulated to obtain a coagulum; an operation in which the coagulum is dewatered; and an operation in which the dewatered coagulum is plasticized as it is dried by means of an extruder; wherein, during the operation in which the dewatered coagulum is plasticized as it is dried, the coagulum comprises a peptizing agent.

A method of recovering nitrile rubber from water-containing crumbs includes crumb-like nitrile rubber using an extruder in which a screw is disposed inside a barrel so as to be capable of being rotationally driven. The barrel is formed with at least a washing zone. The method includes supplying washing water to the washing zone at a water pressure of 0.2 MPa or higher while mixing the crumb-like nitrile rubber and the supplied washing water in the washing zone, thereby washing the crumb-like nitrile rubber.

A method for producing a synthetic polyisoprene latex, including a step of mixing a latex of synthetic polyisoprene (A) synthesized by use of a Ziegler type catalyst and a latex of synthetic polyisoprene (B) synthesized by use of an organic alkali metal catalyst at a weight ratio of “synthetic polyisoprene (A): synthetic polyisoprene (B)=10:90 to 90:10”. In the method, preferably, the weight average molecular weight of the synthetic polyisoprene (A) is 100,000 to 3,000,000 and the weight average molecular weight of the synthetic polyisoprene (B) is 1,000,000 to 5,000,000.

A method for producing a synthetic polyisoprene latex, including a step of mixing a latex of synthetic polyisoprene (A) synthesized by use of a Ziegler type catalyst and a latex of synthetic polyisoprene (B) synthesized by use of an organic alkali metal catalyst at a weight ratio of “synthetic polyisoprene (A): synthetic polyisoprene (B)=10:90 to 90:10”. In the method, preferably, the weight average molecular weight of the synthetic polyisoprene (A) is 100,000 to 3,000,000 and the weight average molecular weight of the synthetic polyisoprene (B) is 1,000,000 to 5,000,000.

A process for drying a natural rubber starting from a wet natural rubber coagulum is provided. In a first step, the wet natural rubber coagulum is compressed at a temperature ranging from 185 C. to 210 C., then in a second step subjected to a flash adiabatic expansion at a differential pressure of at least 100 bar. Optionally supplemented by convective drying or by repeating the first and second steps, the process leads to a dry natural rubber having a nitrogen content of at most 0.3%.

A process for drying a natural rubber starting from a wet natural rubber coagulum is provided. In a first step, the wet natural rubber coagulum is compressed at a temperature ranging from 185 C. to 210 C., then in a second step subjected to a flash adiabatic expansion at a differential pressure of at least 100 bar. Optionally supplemented by convective drying or by repeating the first and second steps, the process leads to a dry natural rubber having a nitrogen content of at most 0.3%.

A masterbatch manufacturing method in accordance with the present disclosure comprises an operation in which pre-coagulation rubber latex comprising filler is coagulated to obtain a coagulum; an operation in which the coagulum is dewatered; and an operation in which the dewatered coagulum is plasticized as it is dried by means of an extruder; wherein, during the operation in which the dewatered coagulum is plasticized as it is dried, the coagulum comprises a peptizing agent.

A masterbatch manufacturing method in accordance with the present disclosure comprises an operation in which pre-coagulation rubber latex comprising filler is coagulated to obtain a coagulum; an operation in which the coagulum is dewatered; and an operation in which the dewatered coagulum is plasticized as it is dried by means of an extruder; wherein, during the operation in which the dewatered coagulum is plasticized as it is dried, the coagulum comprises a peptizing agent.

A method for producing a synthetic polyisoprene latex, including a step of mixing a latex of synthetic polyisoprene (A) synthesized by use of a Ziegler type catalyst and a latex of synthetic polyisoprene (B) synthesized by use of an organic alkali metal catalyst at a weight ratio of synthetic polyisoprene (A): synthetic polyisoprene (B)=10:90 to 90:10. In the method, preferably, the weight average molecular weight of the synthetic polyisoprene (A) is 100,000 to 3,000,000 and the weight average molecular weight of the synthetic polyisoprene (B) is 1,000,000 to 5,000,000.