US4097667A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydroxyalkyl cellulose ethers
Assignee: Hoechst AG
•
Filing: 1976-12-16
•
Granted: 1978-06-27
•
Expires: 1996-12-16
Abstract
Abstract Disclosed is a process for the chemical modification of a water-soluble cellulose ether, which comprises reacting the ether with a chloroformic acid ester in an aqueous organic medium containing alkali hydroxide, whereby the cellulose ether is rendered at least partially insoluble in water. The modified cellulose ether may be easily dispersed in water and redissolved to form a smooth solution of the original water-soluble ether by adding sufficient alkali to the dispersion to reuse its pH to at least about 11, preferably to about 12.
Inventors
- 👤 Arno Holst
- 👤 Michael Kostrzewa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:40
CPC Classifications
C; C08; C08B; C08B15/00; C08B15/005
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
47 words
A process for the modification of a cellulose ether containing hydroxyalkyl groups, which comprises the step of reacting said ether with a chloroformic acid ester in an aqueous organic medium containing an alkali metal hydroxide, whereby the cellulose ether is rendered at least partially insoluble in water.
Claim 2
Dependent Claim
47 words
A process for the modification of a cellulose ether containing hydroxyalkyl groups, which comprises the step of reacting said ether with a chloroformic acid ester in an aqueous organic medium containing an alkali metal hydroxide, whereby the cellulose ether is rendered at least partially insoluble in water.
Claim 3
Dependent Claim
20 words
The process as claimed in claim 1, wherein the reaction medium contains at most about 40% by weight of water.
Claim 4
Dependent Claim
21 words
The process as claimed in claim 1, wherein the reaction medium contains at least about 10 % by weight of water.
Claim 5
Dependent Claim
24 words
The process as claimed in claim 1, wherein the molar ratio of alkali hydroxide to chloroformic acid ester is from about 1:0.9 to 1:1.1.
Claim 6
Dependent Claim
19 words
The process as claimed in claim 4, which is carried out at from about 20° C to 40° C.
Claim 7
Dependent Claim
26 words
The process as claimed in claim 1, wherein the chloroformic acid ester is present in proportion of at least 0.025 mole per mole of cellulose ether.
Claim 8
Dependent Claim
26 words
The process as claimed in claim 6, wherein the ester is present in a proportion of between 0.1 to 0.6 mole per mole of cellulose ether.
Claim 9
Dependent Claim
26 words
The process as claimed in claim 1, wherein a chloroformic acid ester of a monohydric alcohol having from 1 to about 8 carbon atoms is used.
Claim 10
Dependent Claim
12 words
The process as claimed in claim 8, wherein methyl chloroformate is used.
Claim 11
Dependent Claim
16 words
The process as claimed in claim 1, wherein the cellulose ether additionally contains methyl ether groups.
Claim 12
Dependent Claim
20 words
The process as claimed in claim 1, wherein the organic solvent ingredient of the reaction medium is isopropanol or tert.-butanol.
Claim 13
Dependent Claim
44 words
A process for dissolving the modified cellulose ether as produced by the process as claimed in claim 1 which comprises the steps of introducing the ether into water and subsequently raising the pH of the water to a value of at least about 11.
References Cited (Backward Citations)
US2330263A
Cited
US2602789A
Cited
US3072635A
Cited
US3287353A
Cited
US3527751A
Cited
GB1289549A
Cited
US3705890A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-06-26 | 1981-12-26 | 1982-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-26 | 1985-12-26 | 1986-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-26 | 1989-12-26 | 1990-06-27 | $7700.00 | Window Closed / Lapsed |