US4820813A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Grinding process for high viscosity cellulose ethers
Assignee: Dow Chemical Co
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Filing: 1988-02-12
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Granted: 1989-04-11
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Expires: 2008-02-12
Abstract
Abstract High viscosity cellulose ether products are produced by grinding a substantially dry high molecular weight cellulose ether under conditions of mild mechanical impact such as those encountered in a high speed air swept impact mill. It has been found that such a cellulose ether product has several times the intrinsic viscosity of a product of substantially equivalent particle size by ball mill or hammer mill grinding.
Inventors
- 👤 Gary J. Schulz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:20
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/12; C08B; C08B11/00; C08B11/20; C08J3/122; C08J2301/00; C08J2301/08; C08J2301/26
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
60 words
A process of reducing the particle size of a high molecular weight, a high viscosity cellulose ether without substantial change in viscosity, which process comprises grinding a substantially dry, high molecular weight cellulose ether in a high speed air swept impact mill, wherein prior to grinding, the cellulose ether has a viscosity greater than about 100,000 cps at 20° C.
Claim 2
Dependent Claim
60 words
A process of reducing the particle size of a high molecular weight, a high viscosity cellulose ether without substantial change in viscosity, which process comprises grinding a substantially dry, high molecular weight cellulose ether in a high speed air swept impact mill, wherein prior to grinding, the cellulose ether has a viscosity greater than about 100,000 cps at 20° C.
Claim 3
Dependent Claim
18 words
The process in claim 1, wherein the cellulose ether product is methylcellulose ether or a hydroxypropyl methylcellulose ether.
Claim 4
Dependent Claim
50 words
The process in claim 2, wherein the methylcellulose ether product has a methoxyl substitution of about 27 to about 32 weight percent and the hydroxypropyl methylcellulose has a hydroxypropyl substitution of about 4 to about 32 weight percent and a methoxyl substitution of about 16 to about 30 weight percent.
Claim 5
Dependent Claim
27 words
The process in claim 1 wherein the high molecular weight cellulose ether, prior to grinding, has a viscosity greater than about 300,000 cps to at 20° C.
Claim 6
Dependent Claim
28 words
The process in claim 1 wherein the high molecular weight cellulose ether, prior to grinding, has a viscosity from about 100,000 to about 300,000 cps at 20° C.
Claim 7
Dependent Claim
24 words
The process in claim 1 wherein the cellulose ether product has a particle size of about from about 40 to about 400 U.S. mesh.
Claim 8
Dependent Claim
22 words
The process in claim 1 wherein the cellulose ether product has a particle size of about 80 to about 325 U.S. mesh.
Claim 9
Dependent Claim
16 words
A high molecular weight, high viscosity cellulose ether product prepared by the process of claim 1.
Claim 10
Dependent Claim
26 words
The product of claim 8 wherein the high molecular weight, high viscosity, cellulose ether product has a viscosity greater than about 100,000 cps at 20° C.
Claim 11
Dependent Claim
28 words
The product of claim 8 wherein the high molecular weight, high viscosity, cellulose ether product has a viscosity from about 100,000 to about 300,000 cps at 20° C.
Claim 12
Dependent Claim
28 words
The product of claim 8 wherein the high molecular weight, high viscosity, cellulose ether product has a particle size of from about 80 to about 325 U.S. mesh.
Claim 13
Dependent Claim
23 words
The product of claim 8 wherein the high molecular weight, high viscosity, cellulose ether product is methylcellulose ether is a hydroxypropyl methylcellulose ether.
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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) | 1992-04-10 | 1992-10-10 | 1993-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-10 | 1996-10-10 | 1997-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-10 | 2000-10-10 | 2001-04-11 | $7700.00 | Window Closed / Lapsed |