Method for dissolving cellulose and method for preparing regenerated fiber

Abstract

The invention relates to a method for dissolving cellulose, comprising the following steps of: under the condition with the temperature being 0-25 DEG C, firstly mixing the cellulose and a solvent with the weight accounting for 30-70wt% of the total weight of the solvent for dissolving the cellulose uniformly by kneading and shearing; then adding the remaining solvent for dissolving the celluloseat the temperature of 15 below zero to 5 DEG C; and putting the mixture at the temperature of 8 below zero to 25 DEG C, kneading, shearing, mixing uniformly and obtaining cellulose solution. The solvent is water solution containing alkali, urea / thiourea and polyethylene glycol. The method can prevent colloidal particles, micelles and white cores from forming when the cellulose is dissolved, thus leading the cellulose to be well dissolved and obtaining uniform solution; and after the cellulose solution is defoamed, spinning solution is treated by secondary coagulating bath with the coagulatingliquid being salt solution to obtain the cellulose fiber, the recovery and utilization cost of the solvent and a coagulating agent is reduced greatly, the rapid coagulation is avoided, the drawing and orientation degree is improved and the regenerated cellulose fiber with better strength is prepared.

Description

technical field [0001] The present invention relates to a method of dissolving cellulose, and a method of producing regenerated cellulose fibers. Background technique [0002] Cellulose is a natural biopolymer material with abundant reserves in nature. It has the characteristics of renewability, biodegradability, biocompatibility, and derivatization. It is widely used in textiles, papermaking, medical treatment, hygiene, and environmental engineering. It is a regenerated cellulose fiber, with its unique luster, good hygroscopicity and textile processability, it has always been an important textile fiber. However, due to the presence of strong intramolecular and intermolecular hydrogen bonds in cellulose, making it neither meltable nor soluble, it is far from being fully utilized. [0003] At present, the technical bottleneck that limits the mass application of cellulose is its low cost, simple process, and pollution-free dissolution and processing. For more than 100 years,...

AI Technical Summary

Problems solved by technology

[0007] The above-mentioned sodium hydroxide / sodium zincate / urea mixed aqueous solution solvent system, because zinc ions are toxic, has strong toxicity to freshwater plants and plankton, and is not suitable for industrial applications; the above-mentioned freezing-thawing technical scheme has been proved by practice. Keep the mixed slurry of cellulose and solvent under freezing conditions (-20°C) for 3 to 8 hours to freeze into ice, and then thaw to dissolve the cellulose to obtain a cellulose solution, which is not easy for industrialization; Pretreat cellulose with sodium oxide or lithium hydroxide aqueous solution, then add urea or thiourea aqueous solution to dissolve, or directly dissolve cellulose in a cooled alkali (sodium hydroxide or lithium hydroxide) / urea or (and) thiourea mixed aqueous solution The method of dissolving and preparing regenerated cellulose fibers has the following disadvantages: the time for maintaining a stable solution state is short, and irreversible gels are easily formed, and high or low temperatures will lead to gelation, especially in terms of cellulose concentration or molecular weight. Higher solution stability is worse; the solvent system still lacks strong dissolving power, and the cellulose concentration that can reach a uniform solution is low; When alkali cellulose is used, it is easy to cause rapid degradation of cellulose, which will significantly reduce the quality of cellulose products made from this cellulose solution.

In the publication number CN101397369A, a kind of sodium hydroxide / polyethylene glycol aqueous solution solvent system and the method for directly dissolving cellulose by freezing-thawing or in a pre-cooled solvent system are disclosed, but practice has proved that this solvent system can dissolve microbes Crystalline cellulose and regenerated cellulose, but the ability to dissolve natural cellulose such as cotton pulp and wood pulp is limited

Images