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Patent US4783510A successfully refreshed from Google Patents.
US4783510A
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Process for improving a water absorbent polyacrylic acid polymer and an improved polymer produced by said process
Assignee: Maruha Nichiro Corp
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Filing: 1987-06-03
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Granted: 1988-11-08
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Expires: 2007-06-03
Abstract
Abstract A process for improving a water absorbent polyacrylic acid polymer in which the polymer is contacted with an aqueous solution containing a water soluble peroxide radical initiator, followed by heating, thereby causing substantially only the surface portion of the polymer to undergo crosslinking with the radical initiator while leaving the remaining core portion of the polymer substantially intact. The improved water absorbent polyacrylic acid polymer is excellent in both water absorbency and water absorption rate, and the hydrogel resulting from absorption of water has a pleasant, non-sticky feel. The improved water absorbent polyacrylic acid polymer can be advantageously utilized to produce a desirable disposable diaper, sanitary napkin, surgical pad, surgical sheet, paper towel or the like.
Inventors
- 👤 Kazuo Saotome
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:16
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/24; C08J3/245; C08J2333/00; C08J2333/02
Claims Analysis
Total Claims: 51
Claim 1
Independent Claim
135 words
A process for improving a water absorbent polyacrylic acid polymer with respect to absorption characteristics thereof which comprises the steps of: (1) contacting with the surface of a water absorbent polyacrylic acid polymer an aqueous solution containing a water soluble peroxide radical initiator, the weight ratio of the water in said aqueous solution to said polymer being from 0.01 to 0.5, thereby causing said polymer substantially only at its surface portion to have said solution absorbed therein; and (2) heating the resulting polymer with its surface portion having said solution absorbed therein at a temperature such that said initiator is decomposed but said polymer is not decomposed, thereby causing said polymer at its surface portion to undergo crosslinking by the action of said initiator while leaving the remaining core portion of said polymer substantially intact.
Claim 2
Dependent Claim
135 words
A process for improving a water absorbent polyacrylic acid polymer with respect to absorption characteristics thereof which comprises the steps of: (1) contacting with the surface of a water absorbent polyacrylic acid polymer an aqueous solution containing a water soluble peroxide radical initiator, the weight ratio of the water in said aqueous solution to said polymer being from 0.01 to 0.5, thereby causing said polymer substantially only at its surface portion to have said solution absorbed therein; and (2) heating the resulting polymer with its surface portion having said solution absorbed therein at a temperature such that said initiator is decomposed but said polymer is not decomposed, thereby causing said polymer at its surface portion to undergo crosslinking by the action of said initiator while leaving the remaining core portion of said polymer substantially intact.
Claim 3
Dependent Claim
19 words
A process according to claim 1, wherein said weight ratio is in the range of from 0.02 to 0.3.
Claim 4
Dependent Claim
19 words
A process according to claim 2, wherein said weight ratio is in the range of from 0.02 to 0.2.
Claim 5
Dependent Claim
19 words
A process according to claim 3, wherein said weight ratio is in the range of from 0.03 to 0.1.
Claim 6
Dependent Claim
38 words
A process according to claim 1, wherein said initiator is at least one member selected from the group consisting of ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, oxalic acid peroxide, acetic acid peroxide and succinic acid peroxide.
Claim 7
Dependent Claim
29 words
A process according to claim 1, wherein said initiator is contained in said aqueous solution in an amount of from 0.01 to 10% by weight based on the polymer.
Claim 8
Dependent Claim
29 words
A process according to claim 6, wherein said initiator is contained in said aqueous solution in an amount of from 0.1 to 5% by weight based on the polymer.
Claim 9
Dependent Claim
29 words
A process according to claim 7, wherein said initiator is contained in said aqueous solution in an amount of from 0.2 to 2% by weight based on the polymer.
Claim 10
Dependent Claim
15 words
A process according to claim 1, wherein said aqueous solution further contains a crosslinking auxiliary.
Claim 11
Dependent Claim
17 words
A process according to claim 9, wherein said crosslinking auxiliary is a hydrophilic polyfunctional olefinically unsaturated compound.
Claim 12
Dependent Claim
29 words
A process according to claim 10, wherein said unsaturated compound is at least one member selected from the group consisting of N,N'-methylenebisacrylamide, ethylene glycol bis(meth)acrylate and polyethylene glycol bis(meth)acrylate.
Claim 13
Dependent Claim
18 words
A process according to claim 1, wherein said aqueous solution further contains a water miscible volatile organic solvent.
Claim 14
Dependent Claim
32 words
A process according to claim 12, wherein said aqueous solution contains said volatile organic solvent in an amount of from 0.5 to 10 parts by volume per part by volume of water.
Claim 15
Dependent Claim
67 words
A process according to claim 1, wherein said water absorbent polyacrylic acid polymer is at least one member selected from the group consisting of a crosslinked acrylic acid homopolymer, a crosslinked acrylic acid copolymer, a saponification product of a copolymer of vinyl acetate and an acrylic ester, a graft crosslinked polymer of starch and acrylic acid and a hydrolyzate of a graft polymer of starch and acrylonitrile.
Claim 16
Dependent Claim
31 words
A process according to claim 1, wherein said water absorbent polyacrylic acid polymer is a gel capable of absorbing from 300 to 1000 g of water per g of the gel.
Claim 17
Dependent Claim
23 words
A process according to claim 1, wherein said water absorbent polyacrylic acid polymer is in a particulate form, fibrous form or film form.
Claim 18
Dependent Claim
26 words
A process according to claim 16, wherein said polymer is in a particulate form and has an average particle diameter of from 10 to 3000 μm.
Claim 19
Dependent Claim
20 words
A process according to claim 17, wherein said polymer has an average particle diameter of from 50 to 1000 μm.
Claim 20
Dependent Claim
20 words
A process according to claim 18, wherein said polymer has an average particle diameter of from 100 to 500 μm.
Claim 21
Dependent Claim
25 words
A process according to claim 16, wherein said polymer is in a film form and has a film thickness of from 5 to 1000 μm.
Claim 22
Dependent Claim
25 words
A process according to claim 16, wherein said polymer is in a fibrous form and has a fiber diameter of from 5 to 1000 μm.
Claim 23
Dependent Claim
26 words
A process according to claim 1, wherein said contacting is performed by spraying said aqueous solution onto the surface of the water absorbent polyacrylic acid polymer.
Claim 24
Dependent Claim
19 words
A process according to claim 1, wherein said decomposition of the peroxide radical initiator is completed within 10 minutes.
Claim 25
Dependent Claim
33 words
A process according to claim 1, wherein said water absorbent polyacrylic acid polymer has carboxyl groups, from 60 to 90% by mole of which is in the form of an alkali metal salt.
Claim 26
Dependent Claim
27 words
A process according to claim 1, wherein said polymer with its surface portion having said aqueous solution absorbed therein is heated in an atmosphere of superheated steam.
Claim 27
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 1.
Claim 28
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 2.
Claim 29
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 3.
Claim 30
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 4.
Claim 31
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 5.
Claim 32
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 6.
Claim 33
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 7.
Claim 34
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 8.
Claim 35
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 9.
Claim 36
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 10.
Claim 37
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 11.
Claim 38
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 12.
Claim 39
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 13.
Claim 40
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 14.
Claim 41
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 15.
Claim 42
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 16.
Claim 43
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 17.
Claim 44
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 18.
Claim 45
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 19.
Claim 46
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 20.
Claim 47
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 21.
Claim 48
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 22.
Claim 49
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 23.
Claim 50
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 24.
Claim 51
Dependent Claim
14 words
An improved water absorbent polyacrylic acid polymer produced by a process of claim 25.
References Cited (Backward Citations)
US3418066A
Cited
DE1932891A1
Cited
US4225650A
Cited
JPS5270648A
Cited
SU737521A1
Cited
JPS60255814A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-08 | 1992-05-09 | 1992-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-08 | 1996-05-09 | 1996-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-08 | 2000-05-09 | 2000-11-08 | $7700.00 | Window Closed / Lapsed |