Patent ID: 6972102

Claim:
A method for the continuous production of an extrusion solution for the formation of cellulosic molded bodies, such as fibers and films, according to the lyocell method, comprising: (a) forming a cellulose suspension comprising cellulose pulp and an aqueous phase in a mass ratio in the range from 1:3 to 1:40 and shearing the cellulose suspension in a first shear zone for a period of time in the range from 5 to 200 minutes, wherein the cellulose suspension further comprises cellulose fine fibers and soluble impurities; (b) dewatering the cellulose suspension to form a damp cellulose material with a cellulose content in the range from 20 to 80 mass-percent, wherein a portion of the aqueous phase from the dewatering is discarded and a portion is recycled for subsequent use in step (a), thereby removing at least a portion of soluble impurities from the aqueous phase while recycling at least a portion of the fine cellulose fibers, (c) conveying the damp cellulose material through a second shear zone in the absence of N-methylmorpholine-N-oxide, wherein the damp cellulose material is homogenized in the second shear zone, and wherein the solubility of the damp cellulose material is increased; (d) adding a sufficient amount of aqueous N-methylmorpholine-N-oxide to the homogenized damp cellulose material to form a cellulose suspension with a content of N-methylmorpholine-N-oxide in the liquid phase in a range from 70 to 80 mass-percent and conveying the homogenized suspension through a third shear zone with the cellulose material essentially completely filling up the available conveyor cross-section in the shear zones; and (e) converting the cellulose suspension in aqueous N-methylmorpholine-N-oxide into the extrusion solution by evaporating water evaporation with shearing in a fourth shear zone thereby reducing localized overheating and damage to the extrusion solution.