GB614659A - Improvements in the production of artificial fibres and other articles of modified cellulose and cellulose esters - Google Patents

Abstract

Formaldehyde or glyoxal and an acid-reacting catalyst are added to a solution in an organic solvent of a cellulose ester having free hydroxyl groups and the solution is formed into the shape of a filament or other article and subjected to such a temperature as to effect simultaneous evaporation of solvent and reaction between the cellulose ester and the aldehyde. Articles having reduced solubilities in organic solvents and higher temperatures of softening are obtained. The modified cellulose ester materials may be subjected to acid or alkaline saponifying treatments, e.g. with solutions of sodium or potassium hydroxide, carbonate, or sulphide, and the ester groups may be entirely removed. The modified regenerated cellulose articles so obtained are insoluble in cuprammonium solution, and are resistant to swelling in aqueous media. Preferably, the formaldehyde or glyoxal is added to the spinning or casting solution in an amount not in excess of 10 per cent of the weight of the cellulose ester. The cellulose ester solution is extruded into an evaporative atmosphere the temperature of which is such that the reaction of the cellulose ester with the aldehyde is initiated. The reaction may be brought to completion while the filament is maintained in the evaporative atmosphere, e.g. by using a long dry spinning cell, or it may be completed subsequently to the stretching and winding up processes, but before all of the solvent has been removed. The reaction may be hastened by heating the filaments but preferably it is allowed to continue to completion at room temperature. The acid-reacting catalyst may be oxalic, tartaric, benzene sulphonic acid, hydrochloric, sulphuric, or phosphoric acid, or an acid salt.