Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Patent
1997-03-03
1999-11-09
Acquah, Samuel A.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
525 5424, 525 5426, 525 63, 524800, 524802, 524804, 524812, 521 53, 521 55, 521 57, 521905, 428403, 428407, B32B 516, C08F 216
Patent
active
059810700
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to water-absorbent agent powders and a manufacturing method of the same, and more particularly to water-absorbent agent powders befitting sanitary materials, which manifest as high an absorbency under pressure as without pressure, excel in safety as evinced by the absence of a residue of a cross-linking agent in the resin, while manifesting a high absorbing rate, and also relates to a manufacturing method of the same.
BACKGROUND OF THE INVENTION
In recent years, a water-absorbent resin is widely used in sanitary goods such as disposable diapers, sanitary napkins, etc., for the purpose of absorbing and holding body fluid such as urine, blood, etc., to prevent clothes from being contaminated.
Examples of the conventionally known water-absorbent resins may be but are not limited to: Unexamined Patent Publication No. 84304/1980 (Tokukaisho 55-84304), Japanese Unexamined Patent Publication No. 108407/1980 (Tokukaisho 55-108407) and Japanese Unexamined Patent Publication No. 133413/1980 (Tokukaisho 55-133413)); Patent Publication No. 43995/1971 (Tokukosho 46-43995)); Patent Publication No. 125468/1976 (Tokukaisho 51-125468)); Patent Publication No. 14689/1977 (Tokukaisho 52-14689)); No. 4,689,408); copolymer of both (Japanese Unexamined Patent Publication No. 15959/1978 (Tokukaisho 53-15959)); Publication No. 154709/1983 (Tokukaisho 58-154709) and Japanese Unexamined Patent Publication No. 154710/1983 (Tokukaisho 58-154710)); 4,389,513); and acrylic acid (EP068189).
The properties which the water-absorbent resins are desired to possess include, for example, high absorbency and high absorbing rate to be manifested on contact with aqueous liquids, liquid permeability, high strength exhibited by the gel swollen with liquid, and ability to aspirate water from the substrate impregnated with aqueous liquid, less residue of monomer (U.S. Pat. No. 4,794,166).
These properties are not necessarily correlated positively to one another, and a problem arises, for example, in that such properties as the liquid permeability, the gel strength, and the absorbing rate are lowered in proportion as the absorbency is heightened.
As a means to improve the various water-absorbent properties of the water-absorbent resin in finely balanced levels, the technique of cross-linking the surface regions of the water-absorbent resin has been known. Various methods have been proposed concerning the technique.
For example, a method using polyhydric alcohols (Japanese Unexamined Patent Application No. 108233/1983 (Tokukaisho 58-108233), and Japanese Unexamined Patent Application No. 16903/1986 (Tokukaisho 61-16903)), a method using polyglycidyl compounds, poly aziridine compounds, polyamine compounds, and polyisocyanate compounds (Japanese Unexamined Patent Application No. 189103/1984 (Tokukaisho 59-189103) and (U.S. Pat. No. 4,666,893)), methods using glyoxal (Japanese Unexamined Patent Application No. 117393/1977 (Tokukaisho 52-117393)) , methods using polyvalent metals (Japanese Unexamined Patent Application No. 136588/1976 (Tokukaisho 51-136588), Japanese Unexamined Patent Application No. 257235/1986 (Tokukaisho 61-257235) and Japanese Unexamined Patent Application No. 7745/1987 (Tokukaisho 62-7745)), methods using a silane coupling agent (Japanese Unexamined Patent Application No. 211305/1986 (Tokukaisho 61-211305), Japanese Unexamined Patent Application No. 252212/1986 (Tokukaisho 61-252212) and Japanese Unexamined Patent Application No. 264006/1986 (Tokukaisho 61-264006)), a method using a monoepoxy compound (Japanese Unexamined Patent Application No. 87638/1992 (Tokukaihei 4-87638)), a method using a polymeric compound having an epoxy group (U.S. Pat. No. 4,758,617), a method using an epoxy compound and a hydroxy compound (Japanese Unexamined Patent Application No. 132103/1990 (Tokukaihei 2-132103)), and a method using an alkylene carbonate (DE-4020780) have been known.
Other than the described methods, methods requiring the presence of an inorganic inactive powder (Japanese Unexami
REFERENCES:
patent: 4666983 (1987-05-01), Tsubakimoto et al.
patent: 4794166 (1988-12-01), Engelhardt et al.
patent: 5229488 (1993-07-01), Nagasuna et al.
patent: 5322896 (1994-06-01), Ueda et al.
patent: 5369148 (1994-11-01), Takahashi et al.
patent: 5382610 (1995-01-01), Harada et al.
patent: 5399591 (1995-03-01), Smith et al.
Harada Nobuyuki
Ishizaki Kunihiko
Nagasuna Kinya
Acquah Samuel A.
Nippon Shokubai Co. Ltd
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