Process for producing cellulose derivatives of high bulk density, good flowability and improved dispersibility in cold water

Patent metadata

Field	Value
Publication number	US-9334416-B2
Application number	US-201214009442-A
Country	US
Kind code	B2
Filing date	Mar 29, 2012
Priority date	Apr 6, 2011
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

A particulate cellulose derivative is obtained in a process of grinding and drying a moist cellulose derivative which comprises the steps of A) providing a cellulose derivative having a moisture content of from 60 to 95 percent, based on the total weight of the moist cellulose derivative, B) grinding and partially drying the moist cellulose derivative in a gas-swept impact mill; and C) contacting the ground and partially dried cellulose derivative with an additional amount of a drying gas outside the gas-swept impact mill. The obtained particulate cellulose derivative has a high untapped bulk density and a good flowability.

First claim

What is claimed is:

1. A process for producing a particulate cellulose derivative comprising the steps of
A) providing a moist cellulose derivative having a moisture content of from 25 to 95 percent, based on the total weight of the moist cellulose derivative, with the proviso that no substantial amount of a surface-treatment additive is added to the cellulose derivative,
B) grinding and partially drying the moist cellulose derivative in a gas-swept impact mill wherein a gas fed into the impact mill has a temperature of 100° C. or less; and
C) contacting the ground and partially dried cellulose derivative with an additional amount of a drying gas outside the gas-swept impact mill, wherein the additional amount of drying gas outside the gas-swept impact mill has a higher temperature than the gas fed into the impact mill
to produce the particulate cellulose derivative.

2. The process of claim 1 wherein the additional amount of drying gas outside the gas-swept impact mill has a temperature that is at least 70° C. higher than the gas fed into the impact mill.

3. The process of claim 1 wherein the ratio of the gas flow in the gas-swept impact mill in step B) and the flow of the additional amount of drying gas in step C) is from 1:10 to 8:1.

4. The process of claim 1 wherein the circumferential speed of the gas-swept impact mill is not more than 100 m/s.

5. The process of claim 1 wherein in a step D) the ground and dried cellulose derivative is sieved through a sieve of from 125 to 400 micrometers mesh size and the cellulose derivative retained on the sieve is recovered.

6. The process of claim 1 wherein the cellulose derivative is a cellulose ether.

7. The process of claim 1 wherein the produced particulate cellulose derivative has an untapped bulk density of at least 370 g/l or a Carr Index of 20 or less or both.

8. A particulate cellulose derivative producible by the process of claim 1 .

9. A method of improving the flowability and/or the cold water dispersibility of a particulate cellulose derivative comprising the steps of
A) providing a moist cellulose derivative having a moisture content of from 25 to 95 percent, based on the total weight of the moist cellulose derivative, with the proviso that no substantial amount of a surface-treatment additive is added to the cellulose derivative,
B) grinding and partially drying the moist cellulose derivative in a gas-swept impact mill wherein a gas fed into the impact mill has a temperature of 100° C. or less; and
C) contacting the ground and partially dried cellulose derivative with an additional amount of a drying gas outside the gas-swept impact mill, wherein the additional amount of drying gas outside the gas-swept impact mill has a higher temperature than the gas fed into the impact mill.

10. A particulate cellulose derivative having an untapped bulk density of at least 370 g/l, a Carr Index of 20 or less, a median Equivalent Projected Circle Diameter (EQPC) of at least 200 micrometers and a viscosity of from 1.2 to 200 mPa·s, measured as a 2% by weight aqueous solution at 20° C., with the proviso that the particulate cellulose derivative does not comprise a substantial amount of a surface-treatement additive.

11. The particulate cellulose derivative of claim 10 having a Carr Index 13 or less.

12. The process of claim 2 wherein the circumferential speed of the gas-swept impact mill is not more than 100 m/s.

Assignees

• Goerlach-Doht Yvonne M
• Hermanns Juergen
• Pierini Peter E
• Grossstueck Marco
• Schreck Michael
• Dow Global Technologies Llc

Inventors

• Goerlach-Doht Yvonne M
• Hermanns Juergen
• Pierini Peter E
• Grossstueck Marco
• Schreck Michael

Classifications

• C08J2301/28

  Alkyl ethers · CPC title

• C08J3/03

  in aqueous media · CPC title

• A61K9/4816

  Wall or shell material · CPC title

• C08B11/22

  Isolation · CPC title

• C08B11/08

  with hydroxylated hydrocarbon radicals; Esters, ethers, or acetals thereof · CPC title