Hoechst Aktiengesellschaft

Klaus Stolting

Hans Kunkler

Wolfgang Schminke

Arno Holst

Josef Hilbig

Hans Macholdt

Apparatus for continuously producing water-soluble hydroxyalkyl cellulose and related ethers comprising, in combination, the following elements connected in series: a stirred kettle for alkalizing cellulose at atmospheric pressure, at least one stirred autoclave for partially etherifying the alkalized cellulose, individual homogenizing pumps at the outlet of the stirred kettle and at the outlet of each stirred autoclave, individual bypass lines leading from the bottom of the stirred kettle to the upper end thereof and from the bottom of each stirred autoclave to the upper end of the same autoclave for circulating slurry from each vessel in a loop, a tubular reactor comprising a plurality of serially-connected, horizontal tubes for completing the etherification of the cellulose slurry, the first tube of the tubular reactor being provided with a non-conveying, homogenizing agitator, and each subsequent tube being provided with a conveying agitator such as an impeller, means such as a jacket for each section of the tubular reactor for adjusting the temperature of a slurry in the tubular reactor, and cooling tube for cooling etherified slurry withdrawn from the tubular reactor.

Apparatus for continuously producing water-soluble hydroxyalkyl

A continuous process for manufacturing water-soluble hydroxyalkyl cellulose, and water-soluble mixed ethers based on hydroxyalkyl cellulose, comprising producing a slurry comprising (by weight) 1 part cellulose, 0.02 to 0.6 parts alkali metal hydroxide, 5 to 10 parts inert organic solvent, and 0.4 to 2.5 parts water; continuously feeding the slurry to a first elevated pressure reactor and mixing the slurry therein with at least one normally gaseous etherifying agent which has been liquified under pressure; maintaining the slurry at a temperature up to 40.degree. C., and a gauge pressure up to 3 bars, for 15 to 90 minutes, to give a degree of substitution from 0.2 to 1.0; continuously circulating the slurry in the first reactor in a loop through a homogenizing device to form a homogenized slurry; continuously feeding the homogenized slurry through a tubular reactor having a conveying device, an inlet, and first and second parts, and reacting the homogenized slurry in the tubular reactor for 70 to 180 minutes at a temperature from 30.degree. to 120.degree. C., under a gauge pressure of up to 10 bars, continuously transferring the reacted slurry into a cooling device; and subsequently purifying the etherified compounds; and apparatus for performing the process utilizing pressurized etherifying reactors and a heated tubular reactor.

Continuous process for producing water-soluble hydroxyalkyl cellulose

In the manufacture of cellulose glycolate, a reaction mixture comprising per 1 part by weight of cellulose 0.2 to 0.6 part by weight of sodium hydroxide, 0.5 to 1.75 parts by weight of sodium monochloroacetate, 7 to 22 parts by weight of isopropanol, and from 20% to 50% by weight, based on the weight of isopropanol, of water is subjected to shearing forces at a temperature less than 30.degree. C to effect intimate mixing and then reacted to cause etherification of the cellulose in a reaction area held at a temperature in the range of 60.degree. C to 90.degree. C and held constant within each section of the reaction area. The residence time of the mixture in the mixing zone is at most one-tenth of its residence time in the reaction area. The solid and liquid components of the reaction mixture after etherification are separated mechanically.

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Wiesbaden, Germany

Klaus Stolting