Wolff Walsrode Ag

Dow Global Technolgoies LLC

Dow Wolff Cellulosics Gmbh

Wolff Cellulosics Gmbh & Co.,

Wolff Cellulosics Gmbh & Co. Kf

Jörn-Bernd Pannek

Hartwig Schlesiger

Wolfgang Dannhorn

Frank Höhl

Roland Bayer

Erik-Andreas Klohr

Jürgen Engelhardt

Arne Henning Kull

Klaus Szablikowski

Werner Lange

Rene Kiesewetter

Bernd Schriewer

Martin Kowollik

René Kiesewetter

Daniel Auriel

Marc Oliver Schmidt

Friedrich-Karl Lampert

Burkhard Kressdorf

Volkhardt Müller

Gerolf Weissach

Wilhelm Oppermann

The present invention relates to a process for preparing cellulose ether products which is characterized in that superabsorbent polymers (SAPs) are dried and milled, or mill-dried, conjointly with moist cellulose ether and also to the cellulose ether products resulting from this process.

Preparation of cellulose ether products of increased viscosity and fineness

A process of preparing alkylhydroxyalkylcellulose (e.g., methylhydroxyethylcellulose and methylhydroxypropylcellulose) by reaction of cellulose in the presence of alkali metal hydroxide with an alkylating agent and a hydroxyalkylating agent is described. The process includes: (a) alkalizing cellulose by means of 0.9 to 2.9 equivalents of an alkali metal hydroxide I/AGU of the cellulose in the form of an aqueous alkali metal hydroxide solution, in the presence of a suspension medium containing at least 0.2 equivalents of an alkylating agent I/AGU of the cellulose; (b) reacting the alkalized cellulose of step (a) with alkylating agent I and a hydroxyalkylating agent at a temperature above 65&#xb0; C.; (c) adding additional alkali metal hydroxide 11 in the form of an aqueous alkali metal hydroxide solution; and (d) adding additional alkylating agent 11 in an amount of at least the absolute value of the difference between (i) the number of equivalents of alkylating agent I/AGU of the cellulose already added, and (ii) the total number of equivalents of alkali metal hydroxide/AGU of the cellulose added. Additional alkylating agent 11 is not added in step (d) if (i) the number of equivalents of alkylating agent I/AGU of the cellulose already added exceeds (ii) the total number of equivalents of alkali metal hydroxide/AGU of the cellulose already added. In a further step (e), the alkylhydroxyalkylcellulose is isolated from the reaction mixture. The isolated alkylhydroxyalkylcellulose may be optionally purified.

Process of preparing alkylhydroxyalkylcellulose

A method of preparing construction material systems is described. The process includes extruding a composition of construction materials and an irreversibly crosslinked cellulose derivative that is prepared by a particular process.

Process for cement extrusion that makes use of crosslinked cellulose additives

A process for preparing cellulose ethers having delayed dissolution in water is described. The process comprises: (a) treating a moist cellulose ether with a solution comprising a dialdehyde; (b) adding an aqueous salt solution to the moist cellulose ether, such that said cellulose ether has a pH of from 6.0 to 8.0, the aqueous salt addition being performed at least one of, (i) prior to step (a), (ii) concurrently with step (a), and (iii) subsequent to step (a); and (c) drying and comminuting the treated cellulose ether of step (b). The cellulose ether, or mixtures of cellulose ethers, prepared by the method of the present invention may be used as protective colloids, thickeners and adhesives.

Process of preparing delayed-dissolution cellulose ethers

Described is a process of preparing alkylhydroxyalkyl cellulose, e.g., methylhydroxypropyl cellulose (MHPC). The process includes: (a) alkylating cellulose with an aqueous caustic solution containing from 1.5 to 5.5 equivalents of alkali metal hydroxide, e.g., NaOH, per anhydroglucose unit (AGU) of said cellulose, in the presence of a suspension agent, e.g., dimethyl ether, which contains alkyl halide, e.g., methyl chloride, in an amount of from (equivalents of alkali metal hydroxide per AGU minus 1.4) to (equivalents of alkali metal hydroxide per AGU plus 0.8); (b) reacting the alkalised cellulose of step (a) with one or more alkylene oxides, e.g., propylene oxide, at a temperature higher than 65&#xb0; C., e.g., 85&#xb0; C.; (c) adding alkyl halide, to the product of step (b), in an amount of at least the difference between (i) the equivalents of alkyl halide per AGU in step a) and (ii) the equivalents of alkali metal hydroxide added per AGU in step (a), provided that the amount of additionally added alkyl halide is at least 0.2 equivalents per AGU; and (d) isolating alkylhydroxyalkyl cellulose from the reaction mixture of step (c). Optionally the isolated alkylhydroxyalkyl cellulose may be purified.

Process for preparing alkylhydroxyalkyl cellulose

The present invention relates to water-soluble, particularly ternary, preferably ionic, cellulose mixed ethers, more particularly to anionic water-soluble cellulose mixed ethers, as additives for drilling fluid applications.

Use of cellulose mixed ethers as additives for earth pressure shields

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Fallingbostel, Germany

Jörn-Bernd Pannek