US4664857A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing a hydrogel
Assignee: Eneos Corp
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Filing: 1985-06-27
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Granted: 1987-05-12
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Expires: 2005-06-27
Abstract
Abstract A hydrogel which has a water content of 20 to 92 weight % and which is stable and superior in mechanical properties is obtained by preparing a 3 to 25 weight % aqueous solution of a polyvinyl alcohol having a degree of hydrolysis not less than 95 mol % and a viscosity-average polymerization degree of not less than 1,500, then pouring the aqueous polyvinyl alcohol solution into a desired shape of a vessel or a mold, then freeze-molding the aqueous polyvinyl alcohol solution at a temperature lower than -6 DEG C., thereafter dehydrating the molded article without thawing it until the dehydration percentage reaches 5 weight % or more and, if required, immersing the dehydrated product in water.
Inventors
- 👤 Masao Nambu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:49
CPC Classifications
B; B01; B01J; B01J20/00; B01J20/28; B01J20/28014; B01J20/28033; B01J13/00; B01J13/0052; B01J13/0065; B01J20/28002; B01J20/28004; B01J20/28042; B01J20/28047; C; C08; C08J; C08J9/00; C08J9/26; C08J2329/00; C08J2329/02; C08J2329/04
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
113 words
A process for preparing a water-insoluble hydrogel which comprises the steps: preparing a 3 to 25 weight % aqueous solution of a polyvinyl alcohol having a degree of hydrolysis not less than 95 mol % and a viscosity-average polymerization degree of not less than 1,500, pouring said aqueous polyvinyl alcohol solution into a desired shape of a vessel or a mold, freeze-molding said poured aqueous polyvinyl alochol solution at a temperature lower than -6° C., vacuum-dehydrating the resulting molded article without thawing it to a dehydration percentage not lower than 5 weight %, and thawing said dehydrated article to provide a water-insoluble hydrogel having a water content of 20 to 92% by weight.
Claim 2
Dependent Claim
113 words
A process for preparing a water-insoluble hydrogel which comprises the steps: preparing a 3 to 25 weight % aqueous solution of a polyvinyl alcohol having a degree of hydrolysis not less than 95 mol % and a viscosity-average polymerization degree of not less than 1,500, pouring said aqueous polyvinyl alcohol solution into a desired shape of a vessel or a mold, freeze-molding said poured aqueous polyvinyl alochol solution at a temperature lower than -6° C., vacuum-dehydrating the resulting molded article without thawing it to a dehydration percentage not lower than 5 weight %, and thawing said dehydrated article to provide a water-insoluble hydrogel having a water content of 20 to 92% by weight.
Claim 3
Dependent Claim
51 words
A process according to claim 1, in which clay minerals of a laminated structure having a three-layer type (2:1 type) composite layer as a basic unit are suspended in said aqueous polyvinyl alcohol solution in an amount of not more than five times by weight the amount of said polyvinyl alcohol.
Claim 4
Dependent Claim
23 words
A process according to claim 2, in which the degree of hydrolysis of said polyvinyl alcohol is not less than 97 mol %.
Claim 5
Dependent Claim
28 words
A process according to claim 1 or claim 2, in which the viscosity-average polymerization degree of said polyvinyl alcohol is in the range of from 1,800 to 2,600.
Claim 6
Dependent Claim
19 words
A process according to claim 1 or claim 2, in which the freeze-molding temperature is lower than -15° C.
Claim 7
Dependent Claim
27 words
A process according to claim 2, in which the mixing ratio of said polyvinyl alcohol to said clay minerals is in the range of 5/1 to 15/1.
Claim 8
Dependent Claim
19 words
A process according to claim 2, in which said clay minerals principally comprise montmorillonite, vermiculite, illite, pyrophyllite, or talc.
Claim 9
Dependent Claim
20 words
A process according to claim 2, in which said clay minerals have a particle size not larger than 0.15 mm.
Claim 10
Dependent Claim
28 words
A process according to claim 1 or claim 2, in which said vessel or mold is a plate having 900 to 500,000 pieces of projections per square meter.
Claim 11
Dependent Claim
18 words
A process according to claim 9, in which said plate is a flat plate or a curved plate.
Claim 12
Dependent Claim
30 words
A process according to claim 9, in which the aqueous solution is applied onto said plate so that the applied thickness is in the range of 0.01 to 5 mm.
Claim 13
Dependent Claim
34 words
A process according to claim 1 or claim 2, in which the resulting hydrogel is further immersed in water until its water content reaches 50 to 95 weight % on a wet body basis.
References Cited (Backward Citations)
JPS521134A
Cited
JPS528071A
Cited
US4305502A
Cited
JPS5571532A
Cited
JPS5625210A
Cited
JPS5625211A
Cited
US4472542A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-11 | 1990-11-10 | 1991-05-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-11 | 1994-11-10 | 1995-05-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-11 | 1998-11-10 | 1999-05-12 | $7700.00 | Window Closed / Lapsed |