Water-soluble hydroxypropyl sulfoethyl cellulose derivatives (HPSEC) having a low degree of substitution and a process for their production

Water-soluble hydroxypropyl sulfoethyl cellulose derivatives having a molar degree of substitution MS with hydroxypropyl groups of less than 2 and an average degree of substitution DS with sulfoethyl groups and optionally other substituents of less than 0.3 and a viscosity of 5 to 80,000 (mPa.s), as measured on a 2%, by weight aqueous solution at a shear rate D of 2.5 sec..sup.-1 and at a temperature of 20.degree. C., said optional other substituents being selected from the group consisting of hydroxybutyl, hydroxy styryl, alkyl, aralkyl and 2-alkoxy-2-hydroxypropyl.