Process for producing cellulose derivatives of high bulk density, good flowability and/or dispersibility in cold water as well as low solution color

Patent metadata

Field	Value
Publication number	US-9340624-B2
Application number	US-201314422253-A
Country	US
Kind code	B2
Filing date	Sep 23, 2013
Priority date	Sep 25, 2012
Publication date	May 17, 2016
Grant date	May 17, 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; C) contacting the ground and partially dried cellulose derivative with an additional amount of a drying gas outside the gas-swept impact mill; and D) subjecting the cellulose derivative to partial depolymerization after having contacted the cellulose derivative with a drying gas in step C). The obtained particulate cellulose derivative has a high untapped bulk density, a good flowability and a low color intensity.

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;
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; and
D) subjecting the cellulose derivative to partial depolymerization after having contacted the cellulose derivative with the drying gas in step C)
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 cellulose derivative provided in step A) has a viscosity of more than 200 mPa·s, measured as a 2 weight-% solution in water at 20° C., and the cellulose derivative is subjected to partial depolymerization to achieve a reduction in viscosity of the cellulose derivative of at least 10 percent.

4. The process of claim 1 wherein the partially depolymerized cellulose derivative has a viscosity of from 1.2 to 200 mPa·s, measured as a 2 weight-% solution in water at 20° C.

5. 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.

6. The process of claim 1 wherein the produced particulate derivative is one of an alkyl cellulose, hydroxyalkyl cellulose or hydroxyalkyl alkylcellulose.

Assignees

• Dow Global Technologies Llc

Inventors

• Goerlach-Doht Yvonne M
• Hermanns Juergen
• Hoelzer Bettina

Classifications

• C08J3/124 Primary

  Treatment for improving the free-flowing characteristics · CPC title

• A61K9/4891

  Coated capsules; Multilayered drug free capsule shells (with drug coating for immediate release A61K9/4808; osmotic devices A61K9/0004) · CPC title

• C08L1/08

  Cellulose derivatives · CPC title

• C08J2301/08

  Cellulose derivatives · CPC title

• Y10T428/2982

  Particulate matter [e.g., sphere, flake, etc.] · CPC title