Water-absorbing resin and method for producing water-absorbing resin
AssigneeNippon Shokubai Co., Ltd.
InventorsRyota WAKABAYASHI, Jumpei Kaneko, Yoshifumi Adachi, Atsuhiro Noda, Kunihiko Ishizaki
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Abstract
Provided is a water-absorbent resin that can sufficiently swell and gel by absorption of an aqueous liquid such as an antifreeze liquid even in a low-temperature environment, in which (a) a value of 0° C. Vortex is 30 seconds or shorter, (b) a ratio of 0° C. Vortex/30° C. Vortex is 5 or less, (c) a GEX value is 17 or more, and (d) a value of CRC is a value exceeding 25 g/g.
Claims11
A water-absorbent resin satisfying the following conditions (a) to (d):
- (a) a value of 0° C. Vortex being 30 seconds or shorter;
- (b) a ratio of the value of 0° C. Vortex to a value of 30° C. Vortex (Vortex ratio (0° C./30° C.)) being 5.0 or less;
- (c) a GEX value being 17 or greater;
- and
- (d) a value of CRC being a value exceeding 25 g/g.
A method for producing a water-absorbent resin, the method comprising a polymerization step of subjecting a monomer composition containing an acid group-containing unsaturated monomer and optionally containing a monomer other than the acid group-containing unsaturated monomer to crosslinking polymerization to obtain a crosslinked hydrogel polymer, wherein
- at least a part of the acid group-containing unsaturated monomer is a neutralized acid group-containing unsaturated monomer,
- the neutralized acid group-containing unsaturated monomer contains one or more salts selected from the group consisting of a potassium salt, a lithium salt, and an ammonium salt,
- a total content of the acid group-containing unsaturated monomer and the monomer other than the acid group-containing unsaturated monomer in the monomer composition is 30 mass % or more and less than 55 mass % with respect to a total mass of the monomer composition, and
- a polymerization initiation temperature in the polymerization step is 60° C. or higher.
Dependencies are inferred from the claim text.