Water-absorbing agent, manufacture method thereof, and absorbent and absorbent article made therefrom
OwnerKatsuyuki Wada, Makoto Nagasawa +1inventors
InventorsKatsuyuki Wada, Makoto Nagasawa, Kunihiko Ishizaki
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Abstract
We have found that to improve the heat retention by diapers and other absorbents, a heat retention indicator 1 of a water-absorbing resin which is defined in the present invention needs be 3.0° C./min or less and also that particular requirements need be met to satisfy this condition. If the requirements are met, a water-absorbing resin, absorbent, and absorbent article can be provided which has a heat retention indicator 1 of 0 to 3.0° C./min or less and which exhibits excellent heat retention and absorption.
Claims14
A water-absorbing agent, comprising a water-absorbing resin having a crosslinking structure constructed by polymerization of an unsaturated monomer component, wherein
- the water-absorbing agent is surface-treated, and
- the water-absorbing agent meets all of properties (1) through (4):
- (1) heat retention indicator 1 (maximum temperature decrease per minute 5 to 10 minutes after 10 times swelling in a 0.90 wt. % sodium chloride at 50° C.) is from 0 to 3.0° C./min;
- (2) a centrifuge retention capacity in a 0.90 wt. % aqueous solution of sodium chloride (30 minute value) is 34 g/g or less;
- (3) an absorbency in a 0.90 wt. % aqueous solution of sodium chloride against a pressure of 2.0 kPa (60 minute value) is less than 30 g/g;
- and
- (4) a saline flow conductivity (SFC) for a 0.69 wt. % aqueous solution of sodium chloride is less than 20×10−7cm3sec/g.
A method of manufacturing a water-absorbing agent containing a water-absorbing resin having a crosslinking structure constructed by polymerization of an unsaturated monomer component, comprising:
- the polymerization step of polymerizing a monomer component containing an acid-group-containing unsaturated monomer as a major component to prepare a water-absorbing resin;
- and
- the surface crosslinking treatment step of surface-crosslinking the water-absorbing resin obtained in the polymerization step,
- wherein
- in the polymerization step,
- the water-absorbing resin is particles,
- the water-absorbing resin has a centrifuge retention capacity of 35 g/g or more in 0.90 wt. % sodium chloride (30 minute value), and
- the monomer component is polymerized so that the water-absorbing resin meets following conditions (1) and (2) on specific particle sizes:
- (1) particles having diameters from 600 to 300 μm as specified by sieve classification account for 60 wt. % or more, and those less than 150 μm account for 3 wt. % or less;
- and
- (2) a standard deviation of logarithm(σζ) of particle size distribution is from 0.250 to 0.400.
- in the surface crosslinking step, the water-absorbing resin meeting conditions (1) and (2) on specific particle sizes is surface crosslinked in a surface crosslinking treatment process.
Dependencies are inferred from the claim text.