Mitsubishi Chemical Corporation

Mitsubishi Petrochemical Company Limited

501 Mitsubishi Petrochemical Company, Ltd.

Kiichi Ito

Takeshi Shibano

Toshiko Nakamura

Shuhei Yada

Yasuyuki Sakakura

Kenji Yoshinaga

Shinji Tsunoi

Seiichiro Iida

Miho Oomori

Sueichi Kato

Shozo Kitagawa

Miho Tanaka

Kazuhiko Higuchi

Tetsuya Yamamoto

A process for producing a highly water-absorptive polymer, which comprises suspending an aqueous solution containing a water-soluble polymerizable monomer and an optional crosslinking agent into droplets in a hydrophobic organic solvent in the presence of a dispersant and a water-soluble radical polymerization initiator, and allowing the water-soluble polymerizable monomer to polymerize in the droplets, wherein the dispersant is a phosphoric ester surface active agent represented by the following general formula [I]: ##STR1## wherein R.sup.1 represents an alkyl or alkylaryl group having 8 to 30 carbon atoms, R.sup.2 represents OH group or a group of the formula --(CH.sub.2 CH.sub.2 O).sub.m --OR.sup.1, and m and n are an integer of 1 to 30, and the aqueous solution is successively fed to the hydrophobic organic solvent so that the droplets of different polymerization degrees can be present in the solvent.

Highly water-absorptive polymer and process for producing the same

There is provided a highly water-absorptive polymer composition comprising:

Highly water-absorptive polymers having enhanced gel strength

A process for producing a highly water absorptive polymer comprising the steps of subjecting a water-soluble ethylenically unsaturated monomer comprising as the main component acrylic acid and/or an alkali metal or ammonium salt thereof, and optionally containing a crosslinking agent to a water-in-oil type of reverse-phase polymerization in the presence of water, a water-soluble radical polymerization initiator, a dispersant and a hydrophobic hydrocarbon solvent to form a slurry of water-containing particles of a highly water absorptive polymer in the solvent, adding a polymerizable monomer to the slurry, and polymerizing the polymerizable monomer to obtain agglomerates of the particles of the highly water absorptive polymer.

Process for the production of highly water absorptive polymers

A process for producing a highly water absorptive polymer, including the step of polymerizing an acrylic monomer including as the main component acrylic acid and/or an alkali metal salt thereof in the presence of a salt of a metal selected from the,group consisting of Fe(II), Fe(III), Cu(II), Mn(II), VO(II), Co(II) and Ni(II).

A process for producing a highly water-absorbing polymer, which comprises treating a water-absorbing polymer containing a carboxyl group and/or a carboxylate group with a silane coupling agent in the presence of water.

Process for producing highly water-absorbing polymer

A 1,2-unsaturated carboxylic acid or its ester such as acrylic or methacrylic acid or its alkyl ester is purified to remove aldehyde impurities contained therein by treating the acid or its ester with a mercapto containing compound in the presence of an acid catalyst.

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Yokkaichi, Japan

Kiichi Ito