Nitto Chemical Industry Co., Ltd.

Mitsubishi Rayon Company, Limited

Diafloc Co., Ltd.

Masaharu Nagahama

Shoichi Kanda

Takeshi Narita

Masahiro Ushigome

Hitoshi Tamura

Teruzo Otsuka

A process for preparing a water-in-oil emulsion of a water-soluble polymer is disclosed, comprising polymerizing at least one water-soluble vinyl monomer in a water-in-oil emulsion, wherein the dissolved oxygen concentration of the emulsion under polymerization is about 100 ppb or less. The desired emulsion can be obtained without being accompanied by the formation of agglomerates.

Process for preparing a water-in-oil emulsion

There is disclosed a process for producing an acrylamide polymer which comprises polymerizing acrylamide monomer alone or a monomer mixture composed of 50 mole % or more of acrylamide monomer and a monomer capable of copolymerizing with acrylamide monomer in the presence of an azo series polymerization initiator and 0.1% by weight or more of 2-mercaptobenzothiazole or a salt thereof based on the weight of the monomer in an aqueous medium having a pH of 6 or higher at a temperature range of 5 to 100.degree. C., and then drying the resulting material.

Process for producing acrylamide polymer

A water-in-oil emulsion of a cationic polymer suitable for inversion, comprising a continuous phase comprising a hydrophobic liquid, a discontinuous phase comprising a water-soluble cationic polymer, and a surface active agent system for inventing the emulsion in water, the system comprising a mixture of at least one alkyl phosphate represented by formula (I) or (II) and at least one other surface active agent compatible with the at least one alkyl phosphate: ##STR1## wherein R.sub.1 represents a saturated or unsaturated hydrocarbon group having from 8 to 18 carbon atoms; X and Y, which may be the same or different, each represents a hydrogen atom, an alkali metal, an ammonium group, or an alkanolamino group; and n1 represents 0 or an integer of from 1 to 4; ##STR2## wherein R.sub.2 and R.sub.3, which may be the same or different, each represents a saturated or unsaturated hydrocarbon group having from 8 to 18 carbon atoms; X represents a hydrogen atom, an alkali metal, an ammonium group, or an alkanolamino group; and n2 and n3 each represents 0 or an integer of from 1 to 4.

Water-in-oil emulsion of cationic polymer

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Kanagawa, Japan

Masaharu Nagahama