US4292426A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of producing hydroxypropyl cellulose
Assignee: Nippon Soda Co Ltd
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Filing: 1980-05-07
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Granted: 1981-09-29
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Expires: 2000-05-07
Abstract
Abstract Hydroxypropyl cellulose having superior solubility in isopropyl alcohol is obtained by reacting an alkali cellulose of unusually low NaOH/cellulose and water/cellulose ratios with propylene oxide in two stage successive reactions interposing an addition of water.
Inventors
- 👤 Seiji Orii
- 👤 Yukio Sasagawa
- 👤 Akinori Ito
- 👤 Hiromi Maruyama
- 👤 Yoshiteru Sakai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:24
CPC Classifications
C; C08; C08B; C08B11/00; C08B11/02; C08B11/04; C08B11/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
133 words
A process of producing hydroxypropyl cellulose which comprises (a) swelling of cellulose with an aqueous sodium hydroxide solution containing 10-50 w% of NaOH. (b) driving out excess aqueous caustic soda solution from the swollen cellulose to prepare a dehydrated cellulose, (c) obtaining an alkali cellulose having the NaOH/cellulose ratio of 0.05-0.16 and the water/cellulose ratio of 0.2-0.5 by washing the dehydrated cellulose with an aqueous caustic soda solution containing less than 7 w% of caustic soda, and subsequent drying of the washed cellulose, (d) reacting the alkali cellulose with propylene oxide in the presence of an inert diluent until M.S. of the reactant reaches to greater than 1.5 but less than 2, (e) adding to the reaction mixture 0.2-0.7 parts of water per one part cellulose in the raw material alkali cellulose, and
Claim 2
Dependent Claim
133 words
A process of producing hydroxypropyl cellulose which comprises (a) swelling of cellulose with an aqueous sodium hydroxide solution containing 10-50 w% of NaOH. (b) driving out excess aqueous caustic soda solution from the swollen cellulose to prepare a dehydrated cellulose, (c) obtaining an alkali cellulose having the NaOH/cellulose ratio of 0.05-0.16 and the water/cellulose ratio of 0.2-0.5 by washing the dehydrated cellulose with an aqueous caustic soda solution containing less than 7 w% of caustic soda, and subsequent drying of the washed cellulose, (d) reacting the alkali cellulose with propylene oxide in the presence of an inert diluent until M.S. of the reactant reaches to greater than 1.5 but less than 2, (e) adding to the reaction mixture 0.2-0.7 parts of water per one part cellulose in the raw material alkali cellulose, and
Claim 3
Dependent Claim
16 words
(f) continuing further the etherification reaction until M.S. of the reactant reaches to greater than 2.5.
Claim 4
Dependent Claim
16 words
(f) continuing further the etherification reaction until M.S. of the reactant reaches to greater than 2.5.
Claim 5
Dependent Claim
75 words
A process as claimed in claim 1, wherein said alkali cellulose is prepared by swelling cellulose with an aqueous sodium hydroxide solution containing 15-25 w% of NaOH, driving out excess aqueous caustic soda solution from the swollen cellulose, washing the dehydrated cellulose with an aqueous caustic soda solution containing 0-4 w% of NaOH, and drying the washed cellulose to obtain the alkali cellulose having the NaOH/cellulose ratio of 0.08-0.12 and the water/cellulose ration of 0.25-0.45.
Claim 6
Dependent Claim
51 words
A Process as claimed in claim 1, said reaction is interrupted when M.S. of the reactant reaches to 1.5-2, and 0.3-0.6 parts of water per one part of cellulose in the raw material alkali cellulose is added, and then the reaction is continued until M.S. of the reactant reaches to 3-4.
Claim 7
Dependent Claim
28 words
A process as claimed in claim 3, said alkali cellulose is reacted with propylene oxide in the presence of an inert diluent composed of hexane and t-butyl alcohol.
References Cited (Backward Citations)
US3131176A
Cited
US3131177A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-28 | 1985-03-30 | 1985-09-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-28 | 1989-03-30 | 1989-09-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-28 | 1993-03-30 | 1993-09-29 | $7700.00 | Window Closed / Lapsed |