US4643856A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of making gelled cellulose triacetate product
Assignee: MOLECULON BIOTECH Inc
•
Filing: 1985-03-21
•
Granted: 1987-02-17
•
Expires: 2005-03-21
Abstract
Abstract Gelled cellulose triacetate products are made by mixing with a solution of the cellulose triacetate an amount of miscible liquid nonsolvent agent insufficient to cause gelling, then cooling the mixture or evaporating the solvent to cause gelling.
Inventors
- 👤 Larry D. Nichols
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:55
CPC Classifications
A; A61; A61K; A61K47/00; A61K47/30; A61K47/36; A61K47/38; A61K9/00; A61K9/0012; A61K9/0014; A61K9/70; A61K9/7023; C; C08; C08B; C08B3/00; C08B3/22; C08L; C08L1/00; C08L1/08; C08L1/10; C08L1/12
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
123 words
A process of preparing a clear gelled cellulose triacetate product which comprises providing a clear homogeneous liquid solution at a temperature of 20° to 60° C. comprising cellulose triacetate having an acetyl content greater than about 42%, and a major proportion of a liquid solvent therefor, mixing with said solution while maintaining its temperature at 20° to 60° C., a clear liquid gelling agent miscible with said solvent, said gelling agent being a nonsolvent for said cellulose triacetate and capable of causing said solution to gel, the amount of said gelling agent being limited to an amount insufficient to cause gelation at said maintained temperature but sufficient to cause gelation when said mixture is chilled, and chilling said mixture to gel said mixture.
Claim 2
Dependent Claim
123 words
A process of preparing a clear gelled cellulose triacetate product which comprises providing a clear homogeneous liquid solution at a temperature of 20° to 60° C. comprising cellulose triacetate having an acetyl content greater than about 42%, and a major proportion of a liquid solvent therefor, mixing with said solution while maintaining its temperature at 20° to 60° C., a clear liquid gelling agent miscible with said solvent, said gelling agent being a nonsolvent for said cellulose triacetate and capable of causing said solution to gel, the amount of said gelling agent being limited to an amount insufficient to cause gelation at said maintained temperature but sufficient to cause gelation when said mixture is chilled, and chilling said mixture to gel said mixture.
Claim 3
Dependent Claim
23 words
A process as claimed in claim 1 in which said mixed solution is shaped to a product configuration prior to said chilling step.
Claim 4
Dependent Claim
31 words
A process as claimed in claim 1 in which said solvent comprises a water-soluble organic acid having 1 to 3 carbon atoms and said gelling agent is water or isopropyl alcohol.
Claim 5
Dependent Claim
21 words
A process as claimed in claim 1 in which said solvent comprises acetic acid and said gelling agent comprises isopropyl alcohol.
Claim 6
Dependent Claim
56 words
A process as claimed in claim 1 including the additional step of contacting said gel with a liquid which is both a nonsolvent for the cellulose triacetate and miscible with the solvent and gelling agent present for a period of time so as to replace substantially all of said solvent and gelling agent with said nonsolvent.
Claim 7
Dependent Claim
26 words
A process as claimed in claim 5 in which said solvent is acetic acid, said gelling agent is isopropyl alcohol, and said miscible nonsolvent is water.
Claim 8
Dependent Claim
110 words
A process of preparing a clear gelled cellulose triacetate product which comprises providing a clear homogeneous liquid solution comprising cellulose triacetate having an acetyl content greater than about 42%, and a volatile organic liquid solvent therefor mixing with said solution a clear liquid gelling agent which is a nonsolvent for said cellulose triacetate and miscible with said volatile solvent and capable of causing said solution to gel, the amount of said gelling agent being limited to an amount insufficient to cause gelling of said mixture under the conditions of mixing, and exposing said mixture to an atmosphere to provide selective evaporation of said solvent from said mixture until gelation occurs.
Claim 9
Dependent Claim
110 words
A process of preparing a clear gelled cellulose triacetate product which comprises providing a clear homogeneous liquid solution comprising cellulose triacetate having an acetyl content greater than about 42%, and a volatile organic liquid solvent therefor mixing with said solution a clear liquid gelling agent which is a nonsolvent for said cellulose triacetate and miscible with said volatile solvent and capable of causing said solution to gel, the amount of said gelling agent being limited to an amount insufficient to cause gelling of said mixture under the conditions of mixing, and exposing said mixture to an atmosphere to provide selective evaporation of said solvent from said mixture until gelation occurs.
Claim 10
Dependent Claim
23 words
A process as claimed in claim 7 in which said mixed solution is shaped to a product configuration prior to said evaporation step.
Claim 11
Dependent Claim
17 words
A process as claimed in claim 7 in which said volatile solvent is methylene chloride or chloroform.
Claim 12
Dependent Claim
25 words
A process as claimed in claim 7 in which said mixture is maintained at a temperature from 20° to 65° C. during said evaporation step.
Claim 13
Dependent Claim
31 words
A process as claimed in claim 7 in which said solvent is a water-miscible organic acid having 1 to 3 carbon atoms and said gelling agent is water or isopropyl alcohol.
Claim 14
Dependent Claim
21 words
A process as claimed in claim 7 in which said solvent comprises acetic acid and said gelling agent comprises isopropyl alcohol.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-16 | 1990-08-18 | 1991-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-16 | 1994-08-18 | 1995-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-16 | 1998-08-18 | 1999-02-17 | $7700.00 | Window Closed / Lapsed |