Wolff Walsrode Ag

Dow Global Technolgoies LLC

Wolff Cellulosics Gmbh Co. Kg

Gerd Sonnenberg

Hartwig Schlesiger

Martin Morning

Gunter Weber

Wolfgang Dannhorn

Erik-Andreas Klohr

Dieter Herzog

Martin Kowollik

Stefan Michel

Oke Brauer

René Kiesewetter

Lutz Riechardt

Volker Eckhardt

Bernd Haase

Helmut Holste

Dietrich Tegtmeier

Rudolf Heidemann

Bernhard Kranz

Torsten Holtk&ouml;tter

The present invention describes a process for preparing methylhydroxyalkylcellulose having a small number of colored particles by separation of methylhydroxyalkylcellulose from aqueous suspension with subsequent washing of the methylhydroxyalkylcellulose using a specially equipped rotary pressure filter.

Process for preparing methylhydroxyalkylcellulose having a small number of coloured particles

The present invention relates to a new, particularly economical process for preparing particulate water-soluble cellulose derivatives. The process involves forming a feed composition of swollen and/or dissolved cellulose derivative, and water. The feed composition is contacted with a superheated gas mixture, in a sieve-free high rotational speed gas jet impact mill, and the cellulose derivative of the feed composition is converted into a solid state form of finely particulate particles. The superheated gas mixture, with which the feed composition is contacted, is selected from: (i) a superheated gaseous mixture of steam and an inert gas; and (ii) a superheated gas mixture of steam and air. The superheated gas mixture has a steam content of 40 wt. % to 99 wt. %, based on the total weight of the superheated gas mixture.

Process for producing particulate, water-soluble cellulose derivatives using a superheated gas mixture containing steam

A process of both milling and drying a solvent-moist material (e.g., water-moist methylhydroxyethylcellulose) is described. The process includes, (a) providing a mill-dryer () which includes, in series, a heat exchanger (), a mill () and a particulate separating apparatus () connected by conduits (), () and (), which together define a mill-dryer circuit (). The mill-dryer () also includes a bypass conduit (), which provides optionally at least partial gaseous bypass of the heat exchanger (). The process further includes: (b) introducing the solvent-moist material into the mill (); (c) circulating a vapor stream (e.g., a steam/air stream) throughout the mill-dryer circuit (); (d) heating the vapor stream by means of passage through the heat-exchanger (); (e) forwarding milled particulate material from the mill () to the particulate separating apparatus () by means of conduit (); (f) separating the particulate material from the vapor stream in the particulate separating apparatus (); (g) forwarding the vapor stream from the particulate separating apparatus () through conduits (); and (h) controlling the temperature of the vapor stream by optionally forwarding at least some of the vapor stream through the bypass line ().

Process and apparatus for combined milling and drying

Process and apparatus for the industrial preparation of methylhydroxyalkylcellulose

The present invention relates to a process for producing methyl hydroxyalkyl cellulose ethers by alkalisation and etherification of celluloses, rinsing the methyl hydroxyalkyl cellulose ethers with water at higher temperatures and recovering the short-chain cellulose ethers that are soluble in the wash water, wherein the wash water containing sodium chloride and organic by-products is passed across a first stage of a membrane filtration having a molecular cut size of 200 to 150,000 Dalton, is concentrated during this process and passes across a second stage of a membrane filtration.

Process for producing methyl hydroxyalkyl cellulose ethers

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Walsrode, Germany

Gerd Sonnenberg