Patent US4477657A successfully refreshed from Google Patents.
US4477657A
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Process for preparing hydroxyalkylcellulose ethers
Assignee: Dow Chemical Co
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Filing: 1983-07-08
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Granted: 1984-10-16
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Expires: 2003-07-08
Abstract
Abstract Higher reaction efficiencies are seen in cellulose etherification reactions when the reagents are continuously added to alkali cellulose at elevated temperatures. In particular, mixed hydroxyalkylcellulose ethers are prepared with higher reaction efficiencies using this process. In an especially preferred embodiment, hydroxypropylmethylcellulose is prepared by continuously adding propylene oxide to heated cellulose containing a small amount of caustic, adding more caustic and then continuously adding methyl chloride at elevated temperatures.
Inventors
- 👤 Carl P. Strange
- 👤 Christopher D. Messelt
- 👤 Clark W. Gibson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:01
CPC Classifications
C; C08; C08B; C08B11/00; C08B11/02; C08B11/04; C08B11/08; C08B11/193
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
105 words
The process for preparinq mixed hydroxyalkylcellulose ethers containing C 3 or higher hydroxyalkoxyl substituents, said process comprising the steps of (a) forming a reaction mass comprising cellulose and an amount of an alkali metal hydroxide at least sufficient to break up the crystallinity of the cellulose and to catalyze a reaction between cellulose and an alkylene oxide and (b) continuously adding a C 3 or higher alkylene oxide and an etherifying agent other than an alkylene oxide to the reaction mass under conditions including an elevated temperature such that the alkylene oxide and the etherifying agent react with the cellulose to attach ether groups thereto.
Claim 2
Dependent Claim
105 words
The process for preparinq mixed hydroxyalkylcellulose ethers containing C 3 or higher hydroxyalkoxyl substituents, said process comprising the steps of (a) forming a reaction mass comprising cellulose and an amount of an alkali metal hydroxide at least sufficient to break up the crystallinity of the cellulose and to catalyze a reaction between cellulose and an alkylene oxide and (b) continuously adding a C 3 or higher alkylene oxide and an etherifying agent other than an alkylene oxide to the reaction mass under conditions including an elevated temperature such that the alkylene oxide and the etherifying agent react with the cellulose to attach ether groups thereto.
Claim 3
Dependent Claim
16 words
The process of claim 1 wherein the temperature is in the range from about 40°-120° C.
Claim 4
Dependent Claim
12 words
The process of claim 1 wherein the alkylene oxide is propylene oxide.
Claim 5
Dependent Claim
21 words
The process of claim 1 wherein the etherifying agent is a haloaliphatic carboxylic acid, an alkyl halide or a dialkyl sulfate.
Claim 6
Dependent Claim
15 words
The process of claim 4 wherein the etherifying agent is chloroacetic acid or methyl chloride.
Claim 7
Dependent Claim
24 words
The process of claim 1 wherein the etherifying agent is added to the reaction mass after the addition of the alkylene oxide is completed.
Claim 8
Dependent Claim
129 words
A process for preparing mixed hydroxyalkylcellulose ethers, said process comprising the steps of (a) forming a reaction mass comprising cellulose and an amount of an alkali metal hydroxide not substantially in excess of that amount required to break up the crystallinity of the cellulose, (b) continuously adding to the reaction mass a C 3 or higher alkylene oxide under conditions including an elevated temperature such that a desired amount of hydroxyalkoxy groups become attached to the cellulose, then (c) adding an incremental amount of an alkali metal hydroxide to the reaction mass and then (d) continuously adding an etherifying agent which is not an alkylene oxide to the reaction mass under conditions including an elevated temperature such that a desired amount of ether groups become attached to the cellulose.
Claim 9
Dependent Claim
129 words
A process for preparing mixed hydroxyalkylcellulose ethers, said process comprising the steps of (a) forming a reaction mass comprising cellulose and an amount of an alkali metal hydroxide not substantially in excess of that amount required to break up the crystallinity of the cellulose, (b) continuously adding to the reaction mass a C 3 or higher alkylene oxide under conditions including an elevated temperature such that a desired amount of hydroxyalkoxy groups become attached to the cellulose, then (c) adding an incremental amount of an alkali metal hydroxide to the reaction mass and then (d) continuously adding an etherifying agent which is not an alkylene oxide to the reaction mass under conditions including an elevated temperature such that a desired amount of ether groups become attached to the cellulose.
Claim 10
Dependent Claim
26 words
The process of claim 7 wherein steps (b), (c) and (d) are carried out at a temperature in the range from about 40° to 120° C.
Claim 11
Dependent Claim
58 words
The process of claim 8 wherein following the addition of alkylene oxide in step (b), the reaction mixture containing the cellulose pulp, the alkali metal hydroxide and alkylene oxide is maintained at a temperature of 40° to 120° C. from about 15 minutes to 2 hours prior to the addition of said incremental amount of alkali metal hydroxide.
Claim 12
Dependent Claim
40 words
The process of claim 9 wherein following the addition of the etherifying agent in step (d), the reaction mixture is maintained at a temperature of about 40° to about 120° C. for a period of 15 minutes to 2 hours.
Claim 13
Dependent Claim
48 words
The process of claim 8 wherein from about 0.15 to 0.5 part of sodium hydroxide per part by weight of cellulose is employed in step (a) and from about 0.35 to about 1.0 part of sodium hydroxide is employed per part by weight of cellulose in step (c).
Claim 14
Dependent Claim
29 words
The process of claim 8 wherein the alkylene oxide is propylene oxide wherein from about 0.4 to about 5 moles of propylene oxide are employed per mole of cellulose.
Claim 15
Dependent Claim
29 words
The process of claim 12 wherein the etherifying agent is methyl chloride wherein from about 2 to about 4 moles of methyl chloride are employed per mole of cellulose.
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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) | 1987-10-16 | 1988-04-16 | 1988-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-16 | 1992-04-16 | 1992-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-16 | 1996-04-16 | 1996-10-16 | $7700.00 | Window Closed / Lapsed |