Patent US4340731A successfully refreshed from Google Patents.
US4340731A
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Polycarboxyalkyl-cellulose having high fluid absorbing and retaining properties, and process for preparing same
Assignee: Akzo NV
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Filing: 1980-06-19
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Granted: 1982-07-20
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Expires: 2000-06-19
Abstract
Abstract Polycarboxyalkyl-cellulose characterized by exceptionally high fluid absorbing and retaining capacities is obtained by oxidizing, under particular conditions, hydroinsoluble, cross-linked carboxyalkyl-cellulose having a substitution degree greater than 0.35.
Inventors
- 👤 Virginio Colombo
- 👤 Alberto Nicoletti
- 👤 Benito Casu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:02
CPC Classifications
C; C08; C08B; C08B15/00; A; A61; A61L; A61L15/00; A61L15/16; A61L15/22; A61L15/28
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
75 words
Polycarboxyalkyl-cellulose having a degree of substitution greater than 0.35, a cross-linkage comprised between 5% and up to 75% of the substituted groups, a water-solubility below 40% by weight, an absorption and retention of the water comprised between 7,000 and 25,000 ml/100 g of pure product, an absorption and retention of saline solutions or of plasmatic and physiological liquids comprised between 2,500 and 6,000 ml/100 g of pure product, and a pH between 5.5 and 6.4.
Claim 2
Dependent Claim
75 words
Polycarboxyalkyl-cellulose having a degree of substitution greater than 0.35, a cross-linkage comprised between 5% and up to 75% of the substituted groups, a water-solubility below 40% by weight, an absorption and retention of the water comprised between 7,000 and 25,000 ml/100 g of pure product, an absorption and retention of saline solutions or of plasmatic and physiological liquids comprised between 2,500 and 6,000 ml/100 g of pure product, and a pH between 5.5 and 6.4.
Claim 3
Dependent Claim
45 words
Process for increasing the absorption and retention power for water, saline solutions, and physiological and plasmatic liquids, of cross-linked, hydroinsoluble carboxyalkyl-cellulose, and lowering the pH value, which process consists in subjecting the cross-linked, hydroinsoluble carboxyalkyl-cellulose to an oxidizing process at a temperature below 80° C.
Claim 4
Dependent Claim
45 words
Process for increasing the absorption and retention power for water, saline solutions, and physiological and plasmatic liquids, of cross-linked, hydroinsoluble carboxyalkyl-cellulose, and lowering the pH value, which process consists in subjecting the cross-linked, hydroinsoluble carboxyalkyl-cellulose to an oxidizing process at a temperature below 80° C.
Claim 5
Dependent Claim
16 words
The process of claim 2, in which the oxidizing agent is sodium periodate and bromine water.
Claim 6
Dependent Claim
13 words
The process of claim 2, in which the oxidizing agent is hydrogen peroxide.
Claim 7
Dependent Claim
16 words
The process of claim 2, in which the oxidizing agent is lead tetraacetate and bromine water.
Claim 8
Dependent Claim
14 words
The process of claim 2, in which the oxidizing agent is an organic peroxide.
Claim 9
Dependent Claim
44 words
The process of claim 2, in which the cross-linked hydroinsoluble carboxyalkyl-cellulose is obtained by heat-treating hydrosoluble carboxyalkyl cellulose having a degree of substitution greater than 0.35, at a temperature comprised between 85° and 115° C., and at a pH of from 4.4 to 5.5.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-07-19 | 1986-01-18 | 1986-07-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-07-19 | 1990-01-18 | 1990-07-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-07-19 | 1994-01-18 | 1994-07-20 | $7700.00 | Window Closed / Lapsed |