Patent US4404369A successfully refreshed from Google Patents.
US4404369A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing alkali-soluble cellulose derivative
Assignee: Neste Oyj
•
Filing: 1982-01-20
•
Granted: 1983-09-13
•
Expires: 2002-01-20
Abstract
Abstract An alkali-soluble cellulose derivative is produced by treating cellulose with liquid ammonia having urea dissolved therein, removing the ammonia, resulting in cellulose having urea distributed therethrough, and heating the thus obtained cellulose-urea to cause reaction between the urea and cellulose and form alkali-soluble cellulose carbamate. This cellulose carbamate can be precipitated from alkaline solution in the form of cellulose carbamate film or fiber.
Inventors
- 👤 Jouko Huttunen
- 👤 Olli Turunen
- 👤 Leo Mandell
- 👤 Vidar Eklund
- 👤 Kurt Ekman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 20:20
CPC Classifications
C; C08; C08B; C08B15/00; C08B15/05; C08B15/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
95 words
Method of producing alkali-soluble cellulose carbamate, which comprises treating cellulose with a solution consisting essentially of liquid ammonia having urea dissolved therein at a temperature below the temperature of reaction between cellulose and urea, to cause distribution of the urea throughout the cellulose, removing the ammonia at a temperature below the temperature of reaction between cellulose and urea, thereby obtaining cellulose having urea distributed therethrough, and heating the thus obtained cellulose with urea distributed therethrough to a temperature sufficiently high to cause reaction between the cellulose and the urea, thus obtaining an alkali-soluble cellulose carbamate.
Claim 2
Dependent Claim
95 words
Method of producing alkali-soluble cellulose carbamate, which comprises treating cellulose with a solution consisting essentially of liquid ammonia having urea dissolved therein at a temperature below the temperature of reaction between cellulose and urea, to cause distribution of the urea throughout the cellulose, removing the ammonia at a temperature below the temperature of reaction between cellulose and urea, thereby obtaining cellulose having urea distributed therethrough, and heating the thus obtained cellulose with urea distributed therethrough to a temperature sufficiently high to cause reaction between the cellulose and the urea, thus obtaining an alkali-soluble cellulose carbamate.
Claim 3
Dependent Claim
25 words
Method according to claim 1 wherein the cellulose is treated with the liquid ammonia having the urea dissolved therein at a temperature below -33° C.
Claim 4
Dependent Claim
32 words
Method according to claim 1 wherein the cellulose is treated with the liquid ammonia having the urea dissolved therein under pressure at a temperature higher than the boiling point of the ammonia.
Claim 5
Dependent Claim
22 words
Method according to claim 1 wherein the quantity of urea in the ammonia is between about 20-120% by weight of the cellulose.
Claim 6
Dependent Claim
12 words
Method according to claim 1 wherein the ammonia is removed by evaporation.
Claim 7
Dependent Claim
26 words
Method according to claim 1 wherein the cellulose having the urea distributed therethrough is heated to a reaction temperature of between about 110° and 150° C.
Claim 8
Dependent Claim
13 words
Method according to claim 6 wherein the reaction is effect at subatmospheric pressure.
Claim 9
Dependent Claim
26 words
Method according to claim 1 wherein the produced alkali-soluble cellulose carbamate is washed with liquid ammonia at a temperature between about -40° C. and +30° C.
References Cited (Backward Citations)
US1173336A
Cited
US1771461A
Cited
US2007950A
Cited
US2073052A
Cited
US2129708A
Cited
US2134825A
Cited
US2145273A
Cited
US2294925A
Cited
US4124758A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-12 | 1987-03-14 | 1987-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-12 | 1991-03-14 | 1991-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-12 | 1995-03-14 | 1995-09-13 | $7700.00 | Window Closed / Lapsed |