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Patent EP0194877A1 successfully refreshed from Google Patents.
EP0194877A1
Expired / Lapsed
EP
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Purification of cellulose ethers
Assignee: Dow Chemical Co
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Filing: 1986-03-12
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Granted: —
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Expires: 2006-03-12
Abstract
Abstract impurities in cellulose ether compositions are removed by providing a functionally effective thickness of a cellulose ether composition to a filtration device, and contacting the thickness, in a manner such that substantial thickness is maintained, with at least one extracting solution in which the impurities in the cellulose ether are soluble such that a gradient impurity concentration is formed. High purity cellulose ethers are prepared, without experiencing large product losses.
Inventors
- 👤 Gary John Schulz
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 17:01
CPC Classifications
C; C08; C08B; C08B11/00; C08B11/20
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
124 words
A process for removing solvent-soluble impurities from a cellulose ether composition by contacting said composition with a solvent for said impurities, characterised in that said process comprises (a) providing a functionally effective thickness of said cellulose ether composition in a filtration device, (b) contacting said cellulose ether composition with an extracting solution having a solvent for said impurities, in a manner such that said extracting solution can migrate through said thickness of the cellulose ether composition and through said filtration device, and (c) allowing said extracting solution to migrate through said thickness of the cellulose ether composition, such that (1) substantial thickness of the cellulose ether composition is maintained in the filtration device, and (2) a gradient impurity concentration is effected through the thickness.
Claim 2
Dependent Claim
124 words
A process for removing solvent-soluble impurities from a cellulose ether composition by contacting said composition with a solvent for said impurities, characterised in that said process comprises (a) providing a functionally effective thickness of said cellulose ether composition in a filtration device, (b) contacting said cellulose ether composition with an extracting solution having a solvent for said impurities, in a manner such that said extracting solution can migrate through said thickness of the cellulose ether composition and through said filtration device, and (c) allowing said extracting solution to migrate through said thickness of the cellulose ether composition, such that (1) substantial thickness of the cellulose ether composition is maintained in the filtration device, and (2) a gradient impurity concentration is effected through the thickness.
Claim 3
Dependent Claim
49 words
A process as claimed in Claim 1, further comprising the steps of (d) slurrying the cellulose ether composition with a solution having a solvent for said impurities; (e) removing the cellulose ether composition slurry from said filtration device, and (f) isolating the cellulose ether composition from said slurry solution.
Claim 4
Dependent Claim
13 words
A process as claimed in Claim 2, wherein the slurry solution comprises water.
Claim 5
Dependent Claim
28 words
A process as claimed in any one of the preceding claims, wherein the solvent extraction steps (b) and (c) are repeated at least once employing further extracting solution(s).
Claim 6
Dependent Claim
20 words
A process as claimed in any one of the preceding claims, wherein the cellulose ether is a water-soluble cellulose ether.
Claim 7
Dependent Claim
30 words
A process as claimed in any one of the preceding claims, wherein the cellulose ether has a viscosity as a 2 percent solution of less than 10 Pa.s (10,000 cps).
Claim 8
Dependent Claim
20 words
A process as claimed in any one of the preceding claims, wherein the filtration device comprises a vertical cylindrical tank.
Claim 9
Dependent Claim
24 words
A process as claimed in any one of the preceding claims, wherein the extracting solution(s) can insolubilize a portion of the cellulose ether composition.
Claim 10
Dependent Claim
19 words
A process as claimed in any one of the preceding claims, wherein the said extracting solution(s) are aqueous solutions.
Claim 11
Dependent Claim
22 words
A process as claimed in any one of the preceding claims, wherein the said extracting solution(s) contain an amount of the impurities.
Claim 12
Dependent Claim
16 words
A process as claimed in Claim 10, wherein the extracting solution(s) are aqueous sodium chloride solution(s).
Claim 13
Dependent Claim
60 words
A process as claimed in Claim 10 or Claim 11, and in which the solvent extraction steps (b) and (c) are repeated at least once, wherein the extracting solution of the second and any subsequent set of said extraction steps contains a lesser concentration of impurities than the extracting solution of the imediately preceding set of said solvent extraction steps.
Claim 14
Dependent Claim
74 words
A process as claimed in Claim 12, comprising the steps of (d) slurrying the thickness of cellulose ether composition with water, or a solution containing impurities at a concentration about equal to or less than the impurity concentration contained in the extracting solution of the last set of said solvent extraction steps, (e) removing the cellulose ether composition slurry from said filtration device, and (f) isolating the cellulose ether solution from said slurry solution.
Claim 15
Dependent Claim
38 words
A process as claimed in any one of the preceding claims, wherein the cellulose ether composition is provided to the filtration device as a slurry, and the slurry solution is removed after providing said composition to said device.
Claim 16
Dependent Claim
17 words
A process as claimed in Claim 14, wherein the slurry solution contains an amount of the impurities.
Claim 17
Dependent Claim
32 words
A process as claimed in Claim 15, wherein the slurry solution contains a greater amount of impurities than the extracting solution which first contacts the cellulose ether composition in the filtration device.
References Cited (Backward Citations)
US4018681A
Cited
US4229572A
Cited
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