Nitto Kagaku Kogyo Kabushiki Kaisha

Nitto Chemical Industry Co., Ltd.

Seiichi Chiba

Kenzo Ariyama

Iwao Ohshima

Yasuo Ogawa

Zengiro Kawamura

Masahide Ozaki

Process for producing a water-soluble polymer comprising polymerizing an ethylenically unsaturated monomer yielding a water-soluble polymer in an aqueous medium in a polymerization vessel, characterized in that the polymerization system is maintained without stirring at least after the polymerization is initiated, the temperature of the polymerization system is permitted to rise on its own accord, and the non-uniformity of temperature distribution between the center and surroundings of the polymerization system due to the temperature rise is eliminated by heating the polymerization system from the outside. The resulting highly viscous aqueous solution of a polymer in the form of a raw rubbery gel can be recovered from the polymerization vessel without causing the polymer solution to stick to the inner wall surface of the vessel and deposit thereon by suitably selecting the relation between the weight of the gel and the adhesion of the gel to the inner wall of the vessel, thereby permitting the gel content to fall from the vessel by its own weight through the opening in the widely opened condition of the vessel.

Production of water-soluble polymers

A process for producing a substantially nonionic water-soluble acrylamide polymer produced without the occurence of hydrolysis of the acrylamide polymer by heating when the reaction system undergoes an unavoidable heat aging such as due to heat of polymerization comprising polymerizing a comparatively high concentration aqueous solution of acrylamide in the presence of a specific water-soluble nitrogen compound.

Polymerization of acrylamide in the presence of water-soluble nitrogen

Process for purifying an acrylamide including the steps of (1) adding an inorganic base (excluding ammonia) to an aqueous solution containing 15 to 60% by weight of the acrylamide at a temperature of up to 60.degree.C in an amount of 0.1 to 1.5 wt. % based on the acrylamide and (2) blowing a gas, inert to the acrylamide, into the resulting mixture at a hydrogen ion concentration of a pH of 12 to 13.7 and if necessary, (3) subjecting the so treated acrylamide solution to an active carbon adsorption treatment.

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Yokohama, Japan

Seiichi Chiba