US3870703A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of cellulose esters
Assignee: CANADIAN CELLULOSE Co LIM
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Filing: 1973-06-21
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Granted: 1975-03-11
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Expires: 1993-06-21
Abstract
Abstract In the production of a solution of cellulose acetate by esterifying cellulose with acetic anhydride in acetic acid, the improvement which comprises using as the cellulose source wood pulp which has been only partially purified but still contains at least about 5% by weight of hemicellulose. The hemicelluloses are first preferentially etherified or esterified with an agent different from that ultimately employed for esterification. The presence of different groups on the hemicellulose prevents formation of complexes with the cellulose ester during the subsequent conventional esterification, the complexes apparently being the source of filter blockage during ultimate formation of fibers of extrusion.
Inventors
- 👤 Kelly B Gibney
- 👤 John Howard
- 👤 Russell S Evans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:18
CPC Classifications
C; C08; C08B; C08B3/00; C08B3/06
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
154 words
IN THE PRODUCTION OF A SOLUTION OF A CELLULOSE LOWER ALKANOATE SUITABLE FOR USE IN THE FORMATION OF FIBERS WHEREIN A CELLULOSE SOURCE IS SUBJECTED TO THE ESTERIFICATION WITH A LOWER ALKANOIC ACID ANHYDRIDE IN A LOWER ALKANOIC ACID THEREBY FORMING SAID CELLULOSE LOWER ALKANOATE DISSOLVED IN SAID ACID, TH IMPROVEMENT WHICH COMPRISES EMPLOYING AS SAID CELLULOSE SOURCE, CELLULOSE HAVING A HEMICELLULOSE CONTENT IN EXCESS OF ABOUT 5% BY WEIGHT, AND PRIOR TO ESTERIFICATION WITH SAID LOWER ALKANOATE ACID ANHYDRIDE, REACTING SAID CELLULOSE WITH AN ANHYDRIDE ESTERIFYING AGENT DIFFERENT FROM THE LOWER ALKANOATE ESTER UNTIMATELY DESIRED FOR A PERIOD OF FROM 5 TO 30 MINUTES, SAID AGENT BEING EMPLOYED IN MORE THAN THE STIOCHIOMETRIC AMOUNT REQUIRED FOR REACTION WITH THE HEMICELLULOSE, WHEREBY SAID HEMICELLULOSE IS PREFERENTIALLY ESTERIFIED AND WHEREBY THE SOLUTION OF CELLULOSE LOWER ALKANOATE UNTIMATELY PRODUCED IS CHARACTERIZED BY A PERFORMANCE DURING SUBSEQUENT PROCESSING COMPARABLE TO THAT OF INITIALLY MORE PURE CELLULOSE SOURCES.
Claim 2
Dependent Claim
154 words
IN THE PRODUCTION OF A SOLUTION OF A CELLULOSE LOWER ALKANOATE SUITABLE FOR USE IN THE FORMATION OF FIBERS WHEREIN A CELLULOSE SOURCE IS SUBJECTED TO THE ESTERIFICATION WITH A LOWER ALKANOIC ACID ANHYDRIDE IN A LOWER ALKANOIC ACID THEREBY FORMING SAID CELLULOSE LOWER ALKANOATE DISSOLVED IN SAID ACID, TH IMPROVEMENT WHICH COMPRISES EMPLOYING AS SAID CELLULOSE SOURCE, CELLULOSE HAVING A HEMICELLULOSE CONTENT IN EXCESS OF ABOUT 5% BY WEIGHT, AND PRIOR TO ESTERIFICATION WITH SAID LOWER ALKANOATE ACID ANHYDRIDE, REACTING SAID CELLULOSE WITH AN ANHYDRIDE ESTERIFYING AGENT DIFFERENT FROM THE LOWER ALKANOATE ESTER UNTIMATELY DESIRED FOR A PERIOD OF FROM 5 TO 30 MINUTES, SAID AGENT BEING EMPLOYED IN MORE THAN THE STIOCHIOMETRIC AMOUNT REQUIRED FOR REACTION WITH THE HEMICELLULOSE, WHEREBY SAID HEMICELLULOSE IS PREFERENTIALLY ESTERIFIED AND WHEREBY THE SOLUTION OF CELLULOSE LOWER ALKANOATE UNTIMATELY PRODUCED IS CHARACTERIZED BY A PERFORMANCE DURING SUBSEQUENT PROCESSING COMPARABLE TO THAT OF INITIALLY MORE PURE CELLULOSE SOURCES.
Claim 3
Dependent Claim
154 words
In the production of a solution of a cellulose lower alkanoate suitable for use in the formation of fibers wherein a cellulose source is subjected to the esterification with a lower alkanoic acid anhydride in a lower alkanoic acid thereby forming said cellulose lower alkanoate dissolved in said aciD, the improvement which comprises employing as said cellulose source, cellulose having a hemicellulose content in excess of about 5% by weight, and prior to esterification with said lower alkanoate acid anhydride, reacting said cellulose with an anhydride esterifying agent different from the lower alkanoate ester ultimately desired for a period of from 5 to 30 minutes, said agent being employed in more than the stoichiometric amount required for reaction with the hemicellulose, whereby said hemicellulose is preferentially esterified and whereby the solution of cellulose lower alkanoate ultimately produced is characterized by a performance during subsequent processing comparable to that of initially more pure cellulose sources.
Claim 4
Dependent Claim
154 words
In the production of a solution of a cellulose lower alkanoate suitable for use in the formation of fibers wherein a cellulose source is subjected to the esterification with a lower alkanoic acid anhydride in a lower alkanoic acid thereby forming said cellulose lower alkanoate dissolved in said aciD, the improvement which comprises employing as said cellulose source, cellulose having a hemicellulose content in excess of about 5% by weight, and prior to esterification with said lower alkanoate acid anhydride, reacting said cellulose with an anhydride esterifying agent different from the lower alkanoate ester ultimately desired for a period of from 5 to 30 minutes, said agent being employed in more than the stoichiometric amount required for reaction with the hemicellulose, whereby said hemicellulose is preferentially esterified and whereby the solution of cellulose lower alkanoate ultimately produced is characterized by a performance during subsequent processing comparable to that of initially more pure cellulose sources.
Claim 5
Dependent Claim
23 words
The process of claim 1 wherein the cellulose source is wood pulp having a hemicellulose content in excess of about 8% by weight.
Claim 6
Dependent Claim
19 words
The process of claim 1 wherein said lower alkanoic acid is acetic acid and said anhydride is acetic anhydride.
Claim 7
Dependent Claim
18 words
The process of claim 3 wherein said agent is at least one of formic, propionic and butyric anhydrides.
Claim 8
Dependent Claim
41 words
The process of claim 3 wherein said agent is employed in about 1.5 to 2.5 times the stoichiometric amount of the hemicellulose and the reaction is carried to the point where at least about 50 percent of the hemicellulose is reacted.
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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) | 1978-03-10 | 1978-09-09 | 1979-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-10 | 1982-09-09 | 1983-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-10 | 1986-09-09 | 1987-03-11 | $7700.00 | Window Closed / Lapsed |