Mitsubishi Rayon Company, Limited

Kouji Matsumura

Hideaki Makino

Akihiro Toritani

Masaki Sugihara

Shinji Furuta

Makoto Kawano

A production method of polymer particles produces graft polymer particles by contacting a coagulant with a polymer latex (A) obtained by graft polymerizing a monomer containing methylmethacrylate to a rubber-like polymer. The method comprises a coagulation step in which polymer latex (A) is discharged into a stirring tank from an immersed nozzle provided so that the cross-sectional surface area of the discharge portion is 40 mm or more and the direction of discharge is facing in the same direction as the flow in the stirring tank and so that the linear velocity at the nozzle outlet is a velocity of 50-350 mm/s, and contacted with a coagulant to coagulate the graft polymer and obtain a slurry liquid; and a solidification step in which the resulting slurry liquid is held at a temperature of 60-100&deg; C. to solidify the coagulated graft polymer. According to the production method of the present invention, graft polymer particles having superior powder characteristics with few coarse particles and high bulk specific gravity can be obtained without requiring the use of organic solvent or special equipment. Accordingly, polymer particles having superior powder characteristics can be produced in a stable manner and at low cost.

Process for producing polymer particle

A synthetic latex is prepared by charging a portion of water and a monomer as raw materials in a reactor in a ratio of monomer/water, at which a maximum ultimate pressure in said reactor that is attained if an initial composition in said reactor before the initiation of the polymerization is polymerized from a polymerization initiation temperature in an insulated state, is within a practical proof pressure of said reactor; initiating the polymerization; adding dropwise the remainder of said water and said monomer during the polymerization, continuously or intermittently, and performing the emulsion polymerization. As a result, the emulsion polymerization can be stably performed while controlling the temperature and pressure in said reactor in a runaway reaction in all processes of the method of preparing the synthetic latex, thus making it possible to improve the productivity.

Process for producing synthetic latex

A process for production of diene rubber polymers wherein, during production of a diene rubber polymer by emulsion polymerization, the polymerization is initiated using a portion of the starting material and the polymerization is continued with either continuous or intermittent dropwise addition of the remainder of the starting material during the polymerization, and wherein at least &frac12; of the total amount of the water and of the monomer in the starting material used is added dropwise during the polymerization, and the temperature of the dropwise added water and monomer is kept to at least 20&deg; C. below the polymerization temperature. The process can produce industrially useful diene rubber polymer latexes at a high productivity rate.

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Otake, Japan

Kouji Matsumura