US4734097A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Medical material of polyvinyl alcohol and process of making
Assignee: Eneos Corp
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Filing: 1985-03-28
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Granted: 1988-03-29
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Expires: 2005-03-28
Abstract
Abstract Provided is a medical material comprising a molded hydrogel obtained by pouring an aqueous solution containing not less than 6 wt. % of a polyvinyl alcohol which has a degree of hydrolysis not less than 97 mole % and average polymerization degree not less than 1,100, into a desired shape of a vessel or mold, freeze-molding the aqueous solution at a temperature lower than -5 DEG C., then partially dehydrating the resulting molded product without thawing it up to a percentage dehydration not less 5 wt. %, and if required, immersing the partially dehydrated, molded product in water to attain a water content thereof in the range of 45 to 95 wt. %.
Inventors
- 👤 Tatsuzo Tanabe
- 👤 Masao Nambu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:25
CPC Classifications
A; A61; A61L; A61L33/00; A61L33/0005; A61L33/0011; A61L27/00; A61L27/14; A61L27/16; A61L27/50; A61L27/52
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
110 words
The process of preparing a product suitable for medical use composed of a water-insoluble hydrogel having a high water content which comprises preparing an aqueous solution containing not less than 6 weight percent of a polyvinyl alcohol having a degree of hydrolysis of not less than 97 mole percent and an average polymerization degree of not less than 1100, pouring said aqueous polyvinyl alcohol solution into a desired shape of a vessel or mold, freeze-molding said poured aqueous polyvinyl alcohol solution at a temperature below -5° C., and thereafter partially dehydrating the resultant molded product without appreciable thawing thereof to a dehydration percentage of not less than 5 weight percent.
Claim 2
Dependent Claim
110 words
The process of preparing a product suitable for medical use composed of a water-insoluble hydrogel having a high water content which comprises preparing an aqueous solution containing not less than 6 weight percent of a polyvinyl alcohol having a degree of hydrolysis of not less than 97 mole percent and an average polymerization degree of not less than 1100, pouring said aqueous polyvinyl alcohol solution into a desired shape of a vessel or mold, freeze-molding said poured aqueous polyvinyl alcohol solution at a temperature below -5° C., and thereafter partially dehydrating the resultant molded product without appreciable thawing thereof to a dehydration percentage of not less than 5 weight percent.
Claim 3
Dependent Claim
21 words
The process of claim 1 wherein the polymerization degree of the polyvinyl alcohol is in the range of 1,800 to 2,600.
Claim 4
Dependent Claim
15 words
The process of claim 1 wherein the partial dehydration is carried out in a vacuum.
Claim 5
Dependent Claim
18 words
The process of claim 1 wherein the partially dehydrated molded product is thereafter thawed at about room temperature.
Claim 6
Dependent Claim
35 words
The process of claim 4 wherein the thawed product is subjected to a treatment with water or physiological saline so that the resultant product has a water content of from 45 to 95 weight percent.
Claim 7
Dependent Claim
17 words
The process of claim 1 wherein an antithrombotic agent is added to the aqueous polyvinyl alcohol solution.
Claim 8
Dependent Claim
11 words
The process of claim 6 wherein the antithrombotic agent is heparin.
Claim 9
Dependent Claim
9 words
The product according to the process of claim 1.
Claim 10
Dependent Claim
9 words
The product according to the process of claim 5.
Claim 11
Dependent Claim
9 words
The product according to the process of claim 6.
Claim 12
Dependent Claim
9 words
The product according to the process of claim 7.
References Cited (Backward Citations)
GB742900A
Cited
JPS521134A
Cited
JPS528071A
Cited
JPS5571532A
Cited
US4524064A
Cited
US4472542A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-29 | 1991-09-28 | 1992-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-29 | 1995-09-28 | 1996-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-29 | 1999-09-28 | 2000-03-29 | $7700.00 | Window Closed / Lapsed |