US4083906A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the manufacture of open-pore shaped articles of polyvinyl alcohol-acetal sponge
Assignee: Hoechst AG
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Filing: 1975-03-05
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Granted: 1978-04-11
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Expires: 1995-03-05
Abstract
Abstract Starch products which were hitherto used as pore-forming substances in the manufacture of polyvinyl alcohol acetal sponges are replaced by polyethylene glycol or polyacrylamide. This results in a more uniform distribution of pore size, lower shrinkage of the sponge material during the acetalization, and easier washing of the sponge after the acetalization.
Inventors
- 👤 Hermann Schindler
- 👤 Wolfgang Zimmermann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:00
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/28; C08J2329/00; C08J2329/02; C08J2329/04; Y; Y10; Y10S; Y10S521/00; Y10S521/905
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
102 words
In a process for the manufacture of open-pore, shaped articles of polyvinyl alcohol acetal sponge by acid catalyzed acetalization of polyvinyl alcohol in a mixture or emulsion of aqueous solutions of polyvinyl alcohol and a pore-forming substance substantially inert to acetalization, said acetalization being carried out in a mold to produce a shaped article and said shaped article being substantially washed with water to develop its porosity, the improvement which comprises using from 10% to 50% by weight, based on the weight of said polyvinyl alcohol, of a pore-forming substance selected from the group consisting of water-soluble polyethylene glycol and water-soluble polyacrylamide.
Claim 2
Dependent Claim
102 words
In a process for the manufacture of open-pore, shaped articles of polyvinyl alcohol acetal sponge by acid catalyzed acetalization of polyvinyl alcohol in a mixture or emulsion of aqueous solutions of polyvinyl alcohol and a pore-forming substance substantially inert to acetalization, said acetalization being carried out in a mold to produce a shaped article and said shaped article being substantially washed with water to develop its porosity, the improvement which comprises using from 10% to 50% by weight, based on the weight of said polyvinyl alcohol, of a pore-forming substance selected from the group consisting of water-soluble polyethylene glycol and water-soluble polyacrylamide.
Claim 3
Dependent Claim
35 words
A process according to claim 1 wherein the pore-forming substance is selected from polyethylene glycol having an average molecular weight of 1,000 to 100,000 and polyacrylamide having an average molecular weight of 10,000 to 200,000.
Claim 4
Dependent Claim
35 words
A process according to claim 1 wherein the pore-forming substance is selected from polyethylene glycol having an average molecular weight of 10,000 to 50,000 and polyacrylamide having an average molecular weight of 50,000 to 100,000.
References Cited (Backward Citations)
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Cited
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US2825747A
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US3276996A
Cited
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Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-04-10 | 1981-10-10 | 1982-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-04-10 | 1985-10-10 | 1986-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-04-10 | 1989-10-10 | 1990-04-11 | $7700.00 | Window Closed / Lapsed |