Patent US3897382A successfully refreshed from Google Patents.
US3897382A
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Method for the acid hydrolysis of acrylonitrile containing polymers, hydrogels and fibers of products prepared by said method
Assignee: Czech Academy of Sciences
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Filing: 1974-03-20
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Granted: 1975-07-29
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Expires: 1994-03-20
Abstract
Abstract There is disclosed a method for the acid hydrolysis of acrylonitrile-containing polymers comprising hydrolyzing said polymers in the presence of about 40 to about 80% concentrated nitric acid at a temperature of about 25 to about 60*C, cooling said acid reaction mixture to about -20* to about +30*C for a period of time sufficient to reach the desired degree of hydrolysis and products produced therefrom.
Inventors
- 👤 Vladimir Stoy
- 👤 Artur Stoy
- 👤 Renata Urbanova
- 👤 Jaroslav Prokop
- 👤 Josef Kucera
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 05:38
CPC Classifications
C; C08; C08F; C08F8/00; Y; Y10; Y10S; Y10S524/00; Y10S524/916
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
48 words
A METHOD FOR THE ACTIVE HYDROLYSIS OF ACRYLONITRILE-CONTAINING POLYMERS COMPRISING HYDROLYZING SAID POLYMERS IN THE PRESENCE OF ABOUT 40 TO ABOUT 80% CONCENTRATED NITRIC ACID AT A TEMPERATURE OF ABOUT 25 TO ABOUT 60*C, AND COOLING SAID ACID REACTION MIXTURE TO ABOUT -20* TO ABOUT +30*C FOR A
Claim 2
Independent Claim
48 words
A METHOD FOR THE ACTIVE HYDROLYSIS OF ACRYLONITRILE-CONTAINING POLYMERS COMPRISING HYDROLYZING SAID POLYMERS IN THE PRESENCE OF ABOUT 40 TO ABOUT 80% CONCENTRATED NITRIC ACID AT A TEMPERATURE OF ABOUT 25 TO ABOUT 60*C, AND COOLING SAID ACID REACTION MIXTURE TO ABOUT -20* TO ABOUT +30*C FOR A
Claim 3
Dependent Claim
19 words
A method as defined in claim 1 wherein the concentration of said acid is about 50 to about 70%.
Claim 4
Dependent Claim
19 words
A method as defined in claim 1 wherein said cooling is carried out at about -10* to about +20*C.
Claim 5
Dependent Claim
21 words
A method as defined in claim 1 wherein said acid is first heated for about 10 minutes to about 24 hours.
Claim 6
Dependent Claim
19 words
A method as defined in claim 1 wherein said hydrolysis is terminated by separating said polymer from said acid.
Claim 7
Dependent Claim
29 words
A method as defined in claim 1 wherein said polymer is prepared by precipitation or emulsion polymerization and thereafter dissolved in said nitric acid for carrying out said hydrolysis.
Claim 8
Dependent Claim
28 words
A method as defined in claim 1 wherein said polymer is prepared by solution polymerization in said nitric acid as solvent and subsequently subjected to said hydrolysis therein.
Claim 9
Dependent Claim
35 words
A method for the acid hydrolysis of acrylonitrile-containing polymers polymerized at a temperature of less than about 25*C and having at least about 50% conversion comprising carrying out the process as defined in claim 1.
Claim 10
Dependent Claim
24 words
A method as defined in claim 1 wherein said polymer is comprised of acrylonitrile and at least one other ethylenically unsaturated non-amide containing monomer.
Claim 11
Dependent Claim
27 words
A method as defined in claim 9 wherein said other monomer is selected from the group consisting of C1-8 alkyl acrylates or methacrylates, arylalkenes of the formula
Claim 12
Dependent Claim
23 words
A method as defined in claim 9 wherein the ratio of acrylonitrile to said other monomer may vary from about 80:20 to 99:1.
Claim 13
Dependent Claim
12 words
A method as defined in claim 1 wherein said polymer is polyacrylonitrile.
Claim 14
Dependent Claim
20 words
A method as defined in claim 1 wherein said polymer is a copolymer of acrylonitrile and a C1-8 alkyl acrylate.
Claim 15
Dependent Claim
16 words
A method as defined in claim 9 wherein said other monomer is a non-amide containing monomer.
Claim 16
Dependent Claim
13 words
A hydrolyzed acrylonitrile-containing polymer produced by the method as defined in claim 1.
Claim 17
Dependent Claim
13 words
A hydrolyzed acrylonitrile-containing polymer produced by the method as defined in claim 8.
Claim 18
Dependent Claim
23 words
An acrylonitrile-containing fiber comprising the hydrolyzed polymer prepared by the method as defined in claim 1 wet spun in an aqueous coagulating bath.
Claim 19
Dependent Claim
18 words
A cross linked hydrogel produced from the acrylonitrile-containing polymer prepared by the process as defined in claim 19.
Claim 20
Dependent Claim
58 words
The method of preparing cross-linked hydrogel comprising preparing the polymer according to claim 7 wherein no chain-transfer agents are added before of during the polymerization and the polyacrylonitrile lyogel thus formed is subsequently subjected to said hydrolysis, said hydrolysis being terminated by removing the said nitric acid from the gel after a desired degree of hydrolysis is achieved.
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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) | 1978-07-28 | 1979-01-27 | 1979-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-28 | 1983-01-27 | 1983-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-28 | 1987-01-27 | 1987-07-29 | $7700.00 | Window Closed / Lapsed |