Patent US4261149A successfully refreshed from Google Patents.
US4401790A
Expired / Lapsed
US
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Process for the manufacture of polyvinyl alcohol by alcoholysis of a polyvinyl ester
Assignee: Hoechst AG
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Filing: 1981-07-08
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Granted: 1983-08-30
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Expires: 2001-07-08
Abstract
Abstract Polyvinyl alcohol is manufactured by the alcoholysis of polyvinyl esters, in particular polyvinyl acetate, in the presence of a basic catalyst and in the presence of an alkanol as the solvent. The degree of polymerization of the polyvinyl ester used as the starting material is normally within the range from 400 to 10,000. The catalyst used is preferably an alkali metal hydroxide or an alkali metal alcoholate. The alcoholysis is effected by first preparing a solution of the polyvinyl ester, which is then trans-esterified at an elevated temperature. The resulting polyvinyl alcohol exhibits a high degree of purity. It is suitable for use as a base material for the production, by thermoplastic methods, of shaped articles, chiefly by compression molding, injection molding and extrusion.
Inventors
- 👤 Hermann ter Jung
- 👤 Leonhard Reihs
- 👤 Gerhard Roh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:38
CPC Classifications
C; C08; C08F; C08F8/00; C08F8/12; B; B29; B29C; B29C48/00; B29C48/25; B29C48/92; B29C2948/00; B29C2948/92; B29C2948/92504; B29C2948/92514; B29C2948/92704; B29C48/022; B29C48/78; B29C48/80; B29C48/802
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
188 words
A process for the manufacture of polyvinyl alcohol by the alcoholysis of polyvinyl acetate in the presence of a basic catalyst and in the presence of an alkanol as solvent, which comprises first dissolving, in a reactor wherein the reactor used is a continuously working screw extruder, and further equipped with means for heating and cooling, a polyvinyl ester having a degree of polymerization of 400 to 10,000 (determined from the weight average of the molecular weight) in a lower alkanol, wherein the lower alkanol is an alkanol having 1 to 3 carbon atoms, the alkanol being employed in an amount of 20 to 40 percent by weight, relative to the polyvinyl ester, then mixing the resulting solution at a temperature of 30° to 60° C. with a solution of the catalyst wherein the catalyst is an alkali metal hydroxide or an alkali metal alcoholate in a lower alkanol, so as to form a homogeneous mixture, then warming the mixture to a temperature of 70° to 150° C. and, finally, cooling the resulting polyvinyl alcohol to a temperature of 20° to 40° C. and recovering the polyvinyl alcohol.
Claim 2
Dependent Claim
188 words
A process for the manufacture of polyvinyl alcohol by the alcoholysis of polyvinyl acetate in the presence of a basic catalyst and in the presence of an alkanol as solvent, which comprises first dissolving, in a reactor wherein the reactor used is a continuously working screw extruder, and further equipped with means for heating and cooling, a polyvinyl ester having a degree of polymerization of 400 to 10,000 (determined from the weight average of the molecular weight) in a lower alkanol, wherein the lower alkanol is an alkanol having 1 to 3 carbon atoms, the alkanol being employed in an amount of 20 to 40 percent by weight, relative to the polyvinyl ester, then mixing the resulting solution at a temperature of 30° to 60° C. with a solution of the catalyst wherein the catalyst is an alkali metal hydroxide or an alkali metal alcoholate in a lower alkanol, so as to form a homogeneous mixture, then warming the mixture to a temperature of 70° to 150° C. and, finally, cooling the resulting polyvinyl alcohol to a temperature of 20° to 40° C. and recovering the polyvinyl alcohol.
Claim 3
Dependent Claim
26 words
A process as claimed in claim 1, wherein in the recovery of the polyvinyl alcohol, the same is neutralized and neutralization is effected with acetic acid.
References Cited (Backward Citations)
US2227997A
Cited
US2502715A
Cited
US2779752A
Cited
US2950271A
Cited
US3278505A
Cited
US3487060A
Cited
US3541069A
Cited
US3697495A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-08-29 | 1987-02-28 | 1987-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-29 | 1991-02-28 | 1991-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-29 | 1995-02-28 | 1995-08-30 | $7700.00 | Window Closed / Lapsed |