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AssigneeNippon Shokubai Co., Ltd.
InventorsToru Yanase, Kazuki Kimura, Shin-ichi Fujino, Kinya Nagasuna, Kunihiko Ishizaki, Hirotama Fujimaru, Nobuyuki Harada
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A hydrogel polymer obtained by polymerizing a monomer component including acrylic acid (salt) is post-neutralized so that each of polymer particles derived from a polymer produced by neutralizing the hydrogel polymer has an allowable neutralization ratio. The polymer as obtained by neutralizing the hydrogel polymer is reacted with a crosslinking agent reactive to a functional group of the polymer. The allowable neutralization ratio, for example, is a neutralization ratio which is not lower, by not less than 20 mole percent, or more than, at least 55 mole percent, than an average neutralization ratio of a mass of the polymer particles, and the post-neutralization is carried out so that a number of polymer particles having a non-allowable neutralization ratio outside the allowable neutralization range is not more than 10 in 200 polymer particles, thus obtaining a water-absorbent agent having high absorbency under no applied pressure and high pressure wherein the amount of water soluble component is lower compared with the conventional water-absorbent agent and a change in pH of a swollen gel is small.
A water-absorbent agent composed of water-absorbent agent particles obtained by post-neutralizing a hydrogel polymer produced by polymerizing a monomer component including an acid group containing unsaturated monomer (salt),
A water-absorbent agent composed of water absorbent agent particles obtained by post-neutralizing a hydrogel polymer produced by polymerizing a monomer component including an acid group containing unsaturated monomer (salt), wherein an average neutralization ratio of the water-absorbent agent particles is in a range of more than 30 mole percent and less than 95 mole percent, not less than 85 percent of the total number of water-absorbent agent particles have a neutralization ratio in a range of more than 30 mole percent and less than 95 mole percent, and
A water-absorbent agent, wherein a sum of (A) water-absorbent agent particles having a neutralization ratio of not more than 30 mole percent and (B) water-absorbent agent particles having a neutralization ration of not less than 95 mole percent, respectively included in 200 particles of the water-absorbent agent particlesin the water-absorbent agent, is in a range of not less than 1 and not more than 30.
Dependencies are inferred from the claim text.