Patent US4251643A successfully refreshed from Google Patents.
US4251643A
Expired / Lapsed
US
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Absorbents with improved water absorbing power
Assignee: Kuraray Co Ltd
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Filing: 1979-03-16
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Granted: 1981-02-17
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Expires: 1999-03-16
Abstract
Abstract Absorbent materials for aqueous fluids, which absorb fluid rapidly and swell uniformly, comprise modified polyvinyl alcohol polymers obtained by reacting in an anhydrous condition a polyvinyl alcohol polymer with a cyclic acid anhydride and causing partial crosslinking of said polymer. Absorbent articles such as diapers, sanitary napkins, sanitary tampons, blood absorbents for use in surgical operations, bandages and dressings comprise said absorbent materials and fluid absorbing holders therefor.
Inventors
- 👤 Kazuto Harada
- 👤 Toshihiko Yoshitake
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:17
CPC Classifications
A; A61; A61F; A61F13/00; A61F13/15; A61F13/53; A61L; A61L15/00; A61L15/16; A61L15/42; A61L15/60; C; C08; C08F; C08F8/00; C08F8/14; A61F13/534; A61F13/53409; A61F2013/530481; A61F2013/53051; Y; Y10; Y10S; Y10S604/00; Y10S604/904
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
53 words
An absorbent material for aqueous fluids comprising a modified polyvinyl alcohol polymer obtained by a process which consists essentially of reacting in an anhydrous organic diluent a partially or fully saponified polymer or copolymer of a vinyl ester in powder form with a cyclic acid anhydride; thereby causing partial crosslinking of said polymer.
Claim 2
Dependent Claim
53 words
An absorbent material for aqueous fluids comprising a modified polyvinyl alcohol polymer obtained by a process which consists essentially of reacting in an anhydrous organic diluent a partially or fully saponified polymer or copolymer of a vinyl ester in powder form with a cyclic acid anhydride; thereby causing partial crosslinking of said polymer.
Claim 3
Dependent Claim
44 words
The absorbent material of claim 1 wherein at least one compound selected from the group consisting of hydroxides, alkoxides and salts of monovalent metals, ammonia, ammonium salts, amines and amine salts, is reacted with said absorbent material during or after said partial cross linking.
Claim 4
Dependent Claim
35 words
The absorbent material of any of claims 1 or 3 wherein a polyvinyl alcohol having a polymerization degree of 100-5000 and a saponification degree of 50-100 mol % is used as said polyvinyl alcohol polymer.
Claim 5
Dependent Claim
23 words
The absorbent material of any of claims 1 or 3, wherein maleic anhydride or phthalic anhydride is used as said cyclic acid anhydride.
Claim 6
Dependent Claim
26 words
The absorbent material of any of claims 1 or 3 wherein the cross-linking of said polymer or copolymer is carried out in the presence of heat.
Claim 7
Dependent Claim
71 words
An absorbent body which comprises an absorbent material for aqueous fluids comprising a modified polyvinyl alcohol polymer obtained by a process which consists essentially of reacting in an anhydrous organic diluent a partially or fully saponified polymer or copolymer of a vinyl ester in powder form with a cyclic acid anhydride; thereby causing partial crosslinking of said polymer or copolymer; said absorbent material being dispersed in a fluid absorbing holder therefor.
Claim 8
Dependent Claim
71 words
An absorbent body which comprises an absorbent material for aqueous fluids comprising a modified polyvinyl alcohol polymer obtained by a process which consists essentially of reacting in an anhydrous organic diluent a partially or fully saponified polymer or copolymer of a vinyl ester in powder form with a cyclic acid anhydride; thereby causing partial crosslinking of said polymer or copolymer; said absorbent material being dispersed in a fluid absorbing holder therefor.
Claim 9
Dependent Claim
44 words
The absorbent body of claim 6 wherein at least one compound selected from the group consisting of hydroxides, alkoxides, and salts of monovalent metals, ammonia, ammonium salts, amines and amine salts is reacted with said absorbent material during or after said partial cross linking.
Claim 10
Dependent Claim
35 words
The absorbent body of any of claims 6 or 7, wherein a polyvinyl alcohol having a polymerization degree of 100-5000 and a saponification degree of 50-100 mol % is used as said polyvinyl alcohol polymer.
Claim 11
Dependent Claim
23 words
The absorbent body of any of claims 6 or 7, wherein maleic anhydride or phthalic anhydride is used as said cyclic acid anhydride.
Claim 12
Dependent Claim
10 words
The absorbent body of claim 6 which is a diaper.
Claim 13
Dependent Claim
11 words
The absorbent body of claim 6 which is a sanitary napkin.
Claim 14
Dependent Claim
11 words
The absorbent body of claim 6 which is a sanitary tampon.
Claim 15
Independent Claim
19 words
A method of absorbing fluids which comprises contacting said fluids with an absorbent material of claims 1 or 2.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-17 | 1984-08-18 | 1985-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-17 | 1988-08-18 | 1989-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-17 | 1992-08-18 | 1993-02-17 | $7700.00 | Window Closed / Lapsed |