Continuous process for producing water-soluble hydroxyalkyl cellulose and related ethers

A continuous process for the manufacture of water-soluble hydroxyalkyl cellulose, and water-soluble mixed ethers based on hydroxyalkyl cellulose, comprising the steps of:

• producing an initial slurry comprising 1 part by weight of cellulose, about 0.02 to 0.6 parts by weight of an alkali metal hydroxide, about 5 to 10 parts by weight of an inert organic solvent, and about 0.4 to 2.5 parts by weight of water;
• continuously feeding said initial slurry into a first apparatus suitable for operation at elevated pressure, and mixing said initial slurry therein with at least one hydroxyalkyl etherifying agent which is gaseous at atmospheric pressure and at room temperature, and which has been liquefied under pressure;
• maintaining said slurry in said first apparatus at a temperature of up to about 40.degree. C., and under a gauge pressure of up to about 3 bars, for a residence time of from about 15 to 90 minutes, to give a degree of substitution in the range of from about 0.2 to about 1.0;
• continuously circulating said slurry in said first apparatus in a loop through a homogenizing device, to form a homogenized slurry;
• continuously feeding said homogenized slurry through a tubular reactor having a conveying device, an inlet, a first part, and a second part, and reacting said homogenized slurry in said reactor for a residence time of about 70 to 180 minutes at a temperature of from about 30.degree. C. to 120.degree. C., under a gauge pressure of up to about 10 bars;
• and
• continuously transferring the reacted slurry from said reactor into a cooling device.