Patent GB-430352-A (GB)
Title: Improvements in or relating to the treatment or manufacture of cellulose ester filaments, threads, yarns, ribbons and like materials
IPC: D01F2/28
Filed: 1933-12-12
Abstract: Filaments, threads, ribbons, and like materials comprising organic esters of cellulose are subjected to the action of a softening bath containing a swelling agent for the organic ester and a nitrogenous non-metallic base so as simultaneously to soften and partially saponify the materials, and the softened materials are stretched during saponification.  The saponification may extend throughout the whole section of the materials.  The materials may be made by dry or wet spinning methods and advantageously by a wet spinning process in the course of which they are stretched, e.g. to 200 per cent of their original length or more.  Suitable bases are mono-methylamine, ethylamine, propylamine, amylamine, trimethylamine, triethylamine, allylamine, tetramethylammonium hydroxide, ethylene diamine, symmetrical dimethyl ethylene diamine, monomethyl ethylene diamine, propylene diamine, 1.2.3-triamino-propane, a g -diamino-b -hydroxy propane, or piperidine.  Small quantities of substances to accelerate the action of the base as described in Specifications 430,349, 430,350 and 430,351 may be added to the bath, which may also contain a swelling agent such as acetone, diacetone alcohol, cyclohexanol, cyclohexanone, methyl cyclohexanone, dioxane, or methylene ethylene ether.  Preferably, the materials are stretched while being drawn through an aqueous bath containing the base and the swelling agent, advantageously in warp formation.  Successive sets of rollers may perform progressively increasing stretch, or stretching may be effected in stages with rest periods between them.  The materials are preferably stretched to 150--200 per cent or more of their original length, the temperature in most cases being 15--20 DEG  C. or 25--35 DEG  C., and the bath containing 20--60 per cent of swelling agent and 2--10 per cent of the base.  The saponification may reduce the acidyl content by 10--15 per cent or less, but preferably by 20--25 per cent.  In an example, cellulose acetate yarn in warp formation is drawn through an aqueous bath maintained at 20--30 DEG  C. and containing mono-methylamine and 35--45 per cent dioxane at such a rate that it is in contact with the bath for 1--3 minutes and is stretched to 150--200 per cent of its original length.  According to the Provisional Specification the medium containing the base is aqueous and stretching is effected under a tension of 0,3 to 1 gram per denier or even less, and may be 100--500 per cent or more of the original length.  The materials may be made from organic esters of cellulose of high, low, or medium viscosity, e.g. in the case of cellulose acetate the viscosity may be 10--200, comparing a 6 per cent solution of the acetate in acetone at 25 DEG  C. with glycerine at the same temperature as 100.  The materials may be pretrated with a bath containing water and/or soaps or wetting agents, or containing a lower concentration of the swelling agent used in the saponification bath proper, together if desired with a small amount of the saponifying agent.  Specifications 207,562, 323,790, [both in Class 2 (ii)], 340,324, 340,325, 340,326, 340,436, 340,437, 343,062, 371,461, 378,858, 402,104, and 402,141 also are referred to.