# US 4,398,024 A · Process for the purification of cellulose and starch ethers

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- Number: US 4,398,024 A
- Document ID: US4398024A
- Status: Granted
- Kind: A
- Application number: 06/321,067
- Filed: 1981-11-13
- Granted: 1983-08-09
- Earliest claimed: 1980-11-19
- Assignees: Wolff Walsrode AG; Bayer Aktiengesellschaft
- Inventors: Claus-Rudiger Bernert; Christian Kords; Detmar Redeker
- Web page: https://patentgrep.com/patent/US4398024A

## CPC

- C08B 31/08: Ethers
- B04B 1/20: discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
- B04B 3/04: discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
- C08B 11/20: Post-etherification treatments of chemical or physical type, {e.g. mixed etherification in two steps}, including purification
- C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21)
- B04B: CENTRIFUGES (high-speed drum mills B02C19/11; domestic spin driers D06F; analysing, measuring or monitoring physical or chemical properties of samples during centrifuging, see the relevant subclasses for these procedures, e.g. G01N)

## Abstract

A process for purification and working-up of cellulose or starch ethers using a solid-jacket sieve centrifuge for removing the suspension agent extraction with purifying agent and isolation of the purified ether product.

## Claims

### Claim 1

The process for the purification and isolation of a crude reaction product comprising a cellulose or starch ether suspension by removing the suspending agent, said process comprising introducing the cellulose or starch ether suspension into a solid jacket sieve worm centrifuge, separating off the suspending agent leaving a moist solid which is then conveyed to the filter zone of said centrifuge, uniformly contacting the moist solid with a purifying agent, separating the purifying agent from the solid by centrifuge and recovering purified cellulose or starch ether solid.

### Claim 2 (depends on 1)

The process according to claim 1 wherein the process is continuous.

### Claim 3 (depends on 1)

The process according to claim 1 wherein the suspending agent is chemically different from the purifying agent.

### Claim 4 (depends on 1)

The process according to claim 1 wherein the purifying agent is a water/alcohol mixture.