DD214622A1 - METHOD FOR PRODUCING SPINNING CELLULOSE SOLUTIONS - Google Patents

Abstract

The invention relates to a method for producing spinnfaehiger cellulose solutions with organic solvents. It is the object of the invention to provide a process for the solution of the cellulose with organic solvents, which is both environmentally friendly and so economical that it could eliminate the conventional viscose process. According to the invention, the object is achieved in that the activated cellulose is dissolved with hexamethylphosphoric acid triamide or corresponding solvent mixtures with the addition of lithium halides.

Description

Process for the preparation of spinnable cellulose solutions

Field of application of the invention:

The invention relates to a process for preparing spinnable cellulose solutions with organic solvents with the aim of being able to produce from them, for example, threads, films or other shaped structures.

Characteristic of the known technical solutions:

Investing costs and primarily environmental problems make it necessary to find alternatives to the conventional viscose manufacturing process ssu. A large number of patents cite processes for dissolving the cellulose, and organic solvent-containing systems, such as cellulose deformation , are increasingly known. However, none of the processes hitherto known has been able to replace the conventional viscose process as the universal process for the commercial production of regenerated fibers. "The processes described are either not economically viable or also very environmentally unfriendly.

Turbak and coworkers have found * that the LiCl-containing organic solvents dimethylacetamide and i-methyl-2-pyrrolidone, which have been known to be useful in dissolving Iylon and chitin, are also soluble.

sen of cellulose can be used. According to DB-OS 30 27 033 activated cellulose with one of said organic solvent or with a mixture of both and with 3 to 13-weight percent, based on the total weight of the solution of lithium chloride at a temperature at which no significant degradation occurs mixed and dissolved in the absence of another - except the said - polar medium. To activate the cellulose various means, including pre-swelling, use of certain polar media and heating (partly to about 150 ⁰ C) called. However, the specified solvent systems are characterized by limited solubility and high salt use.

It has already been proposed pretreated cellulose with six- or seven-membered saturated heterocyclic ring compounds, the grouping in the ring

contained with the addition of lithium halides to dissolve. Also, these systems have relatively limited solvency and the need for use. Own salt concentrations. All systems mentioned reach the release state only after very long times.

Object of the invention:

The aim of the invention is to significantly increase the solvent power to cellulose by new solvent systems or by mixtures of solvents, to increase the achievable concentration and to shorten the production time significantly, so as to be able to make the solution much more economical.

Explanation of the essence of the invention:

The object of the invention is to find a stable solvent system with which cellulose can be dissolved with high efficiency, high polymer concentrations and few process steps.

It has been found that by using initial wet or in water or other well swelling media such as. As dimethyl sulfoxide, pretreated cellulose, and replacement of the swelling agent against hexamethylphosphoric triamide, by adding a certain, compared to the method mentioned in the procedure significantly reduced amount of LiOl, highly concentrated (up to 20 wt.%), Water-clear solutions are produced in a very short time · For toxicological reasons, ensure that the dissolution units are hermetically sealed. To reduce the toxic loads, the compound described herein without significant loss of solvent power with other polar substances such. B. Dirnethylsulfoxid, dimethylformamide, mixed or by the addition of hexamethylphosphoric triamide to the systems mentioned in the characteristic whose dissolving power can be substantially increased.

Embodiments:

example 1

10 g of beech sulfite pulp are pre-swollen in 1 liter of water. It is then filtered off with suction and exchanged twice with hexamethylphosphoric triamide. It is sucked off again and the pre-swollen cellulose for 2 hours at 5 ⁰ C cooled. Separately, 4 »25 g of LiCl are dissolved in 72 g of hexamethylphosphoric triamide and then the pre-swollen cellulose is introduced. In a few minutes, a highly viscous, water-clear solution is formed, which has no microscopically detectable fiber residues.

Example 2

5 g beech sulfite pulp is pretreated and cooled analogously to Example 1. In a mixture of 35 »8 g of hexamethylphosphoric triamide and 24» 5 g of N-methylcaprolactam 4.25 g of LiCl are dissolved and then added the pretreated cellulose. It forms a clear, easily filterable solution.

Example 3

6 g beech sulfite pulp is pretreated and cooled analogously to Example 1. 8.5 g of LiCl are dissolved in a mixture of 72 g of hexamethylphosphoric triamide and 31 g of dimethyl sulfoxide, and the pretreated cellulose is introduced into this system. The result is a good filterable solution.

Claims (2)

Experiences ana prüche 1. A process for preparing spinnfähiger Oelluloselösungen with organic solvents with the addition of lithium salts, preferably Lithiurahalogeniden, characterized in that for the dissolution of pretreated cellulose hexamethylphosphoric triamide is used. 2. The method according to item 1, characterized in that the compound of the invention with other compounds, such as. As N-methylcaprolactam, N-MethylvaleroIactarn, N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide u. ä «can be mixed in mixing ratios up to 50 mole percent of the second component.