Nippon Shokubai Co., Ltd.

Kohichi Hirota

Yoshio Irie

Nobuyuki Harada

Kinya Nagasuna

Yoshihiko Masuda

Hideaki Nagano

Hideyuki Kubo

A process for preparing an absorbent resin includes the steps of: preparing a first crosslinking agent (A) including at least two polymerizable unsaturated bonds; preparing a second crosslinking agent (B) including at least two polymerizable unsaturated bonds and hydroxyl groups; preparing a crosslinking agent including (A) and (B) with a ratio of (A) to (B) ranging from 95/5 to 50/50; and polymerizing a hydrophilic unsaturated monomer having at least one carboxyl group using the crosslinking agent. The crosslinking agent includes a crosslinking agent which includes a main component at least 90 percent by weight, the main component being an ester having at least two polymerizable unsaturated bonds, wherein the ester is composed of a polyhydroxy alcohol (C) having not more than six carbon atoms and at least three hydroxy groups, and an unsaturated carboxylic acid (D); and a molecular weight ratio of the main component to a standard compound (E) is in the range of from 0.7/1 to less than 1.3/1, (E) being an ester composed of (C) that composes the main component, and (D) that composes the main component, in which all the hydroxy groups in (C) are ester-linked with (D).

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Kobe, Japan

Kohichi Hirota