Patent GB-430489-A (GB)
Title: Improvements in the manufacture of filaments, foils and similar materials having a basis of organic derivative of cellulose
IPC: D01F2/28
Filed: 1933-12-14
Abstract: Artificial filaments, threads, films, and similar materials having a basis of organic derivatives of cellulose, which are soluble in organic solvents, are softened with a medium containing an organic base and subjected to a stretching operation while in such softened condition.  Examples of suitable bases are methylamines, ethylamines, piperidine, pyridine, diamines, 1.2.3.triamino propane, quinoline, aniline, alkylolamines, a g  - diamino - b  - hydroxy propane, urea or substituted ureas such as diethyl urea, tetraphenyl urea, thiourea, or guanidine.  The base may be applied in aqueous, aqueous alcoholic or hydrocarbon media, as a bath treatment, by spraying, or by passage over wicks or rollers.  The materials may be in hank form, or may be softened and stretched while travelling from one point to another, e.g. in warp formation.  In the case of film or foils stretching may be longitudinal and/or transverse.  Stretching may be effected in stages with rest periods between the stages.  The materials may be treated with the medium under such conditions, e.g. at such a temperature that there is substantially no softening action, and then subjected to conditions, e.g. a higher temperature which increases the softening action sufficiently to permit the desired stretching.  The base may be removed after stretching. Preferably the diluent employed with the base is more volatile than the base itself.  Suitable diluents are water, benzene, toluene, ethers, or petroleum hydrocarbons.  Preferably the concentration of base is such that under stretching conditions it is slightly less than that at which it is a solvent for the materials.  The materials may pass over a succession of rollers, softening taking place between the first pairs and stretching between the others.  There may be more than one softening treatment, e.g. the first treatment may be insufficient to soften the base for stretching purposes, the final softening being completed in the second treatment.  When employing volatile bases the bath may be covered with a layer of oil as in Specification 411,094.  Materials may be stretched by 100,200 per cent or more, and may be subjected to shrinking operations prior to or subsequent to the stretching and either continuously with the stretching or as a separate operation.  The materials may be simultaneously saponified with stretching but preferably the concentration of the base, the temperature and/or the time of action are adjusted so that softening takes place without any saponification or any undesired degree of saponification.  In examples cellulose acetate yarns in warp formation are passed through a bath containing 50--55 per cent aqueous solution of pyridine at 25--30 DEG  C.; or 50--60 per cent aqueous piperidine at 20--30 DEG  C.; or 40--45 per cent aqueous trimethylamine at 25--30 DEG  C., and are stretched, e.g. by 100--150 per cent of their original length.  A bath containing 30 per cent ethyl ether, 35 per cent water, and 35 per cent pyridine may be employed, and after passage through the bath the yarns are passed through a chamber at 30 DEG  C. and stretched, e.g. by 100--200 per cent or more of their original length.  A current of air passed through the chamber aids evaporation of the ether.  The yarns are then washed, dried and wound.  Materials containing cellulose acetate are particularly useful for the process, especially cellulose acetate with 50--58 per cent acetyl content calculated as acetic acid.  The cellulose acetate may have any viscosity from, e.g. 12 up to 100 or more calculated on the basis of a 6 per cent solution in acetone compared with glycerine at 100.  Other esters or ethers of cellulose may also be used.  Specifications 207,562, 277,089, 323,790, [all in Class 2 (ii)], 370,430, 371,461, 389,823, 403,106, 417,220, 429,103, 430,352, are referred to.  According to the Provisional Specification the action of the organic bases may be assisted by other compounds, e.g. small proportions of organic solvents such as dioxane, acetone, ethylene methylene ether, glycol mono-acetate, ethyl lactate and diacetone, alcohol.  Inorganic substances such as copper, other metals and metallic compounds may also be employed as described in Specifications 430,349, 430,350, and 430,351.  Specifications 392,185 and 400,597 also are referred to.