GB401335A - Improvements in the manufacture of artificial filaments, threads, ribbons and the like - Google Patents

Abstract

The dry spinning of artificial filaments, threads, ribbons, &c from cellulose acetate and other cellulose esters and ethers of high viscosity characteristics, is facilitated by prolonging the period during which the filaments &c. as extruded from the spinning nozzles remain in a fluid state, as by retarding the evaporation of solvent from the filaments during the early part of their travel or preferably by including in the spinning solution at least 30 per cent of a solvent or partial solvent of relatively low volatility or by using such a solvent as the solvent of the spinning solution. The spinning solution is preferably raised to a relatively high temperature, even to a temperature only slightly below the boiling point as by employing the arrangements described in Specification 398,478. The solvent of low volatility to be added to the spinning solution preferably constitutes over 40 per cent or even in excess of 60 per cent of the entire solvent, and it is preferred to employ such additional solvent as have a boiling point of at least 85 DEG C.; solvents mentioned are the cyclic ether obtained from ethylene glycol and formaldehyde, dioxane, methyldioxanes, dioxydioxane, di-ethers of dioxydioxanes, and their homologues, diacetone alcohol, methyl ethyl ketone, butyrone and ethyl lactate. As high boiling liquids which may constitute the whole of the solvent, dioxane alone or mixed with any of the bodies above referred to, are mentioned. Retardation in the region of the spinning nozzles may be effected by restricting the amount of evaporative mediums contacting with the filaments as by employing vapour-laden atmosphere, for example, by surrounding the spinning nozzle with a depending shield forming an inner compartment from which air is withdrawn at a slower rate or not at all; alternatively, the temperature of the air which in any case is less than that of the spinning solution the latter being regulated by the employment, for example, of the arrangements of Specification 320,632, [Class 2 (ii), Cellulose &c.], is reduced as by injecting cold air into the region of the nozzles as described in Specification 325,233, [Class 2 (ii), Cellulose &c.], or by employing the arrangements of Specifications 399,795, and 399,822. When hollow filaments are desired, the filaments after leaving the region of the nozzles are raised to a suitably high temperature at a point some distance therefrom, as by means of a bank of steam pipes &c. The artificial filaments &c. produced by the above described process, may be subjected to any suitable after-treatment, for example, weighting, mordanting or delustring, or to a stretching operation according to the methods of Specifications 277,089, 323,790, [both in Class 2 (ii), Cellulose &c.], 370,430, and 371,461, or to a shrinking treatment as described in Specifications 380,504, 380,505 and 389,823. In examples, artificial filaments are produced from solutions of high viscosity cellulose acetate in acetone-dioxane, methyl ethyl ketone-ethyl lactate, and ethylene methylene dioxide--dimethyl dioxane. Specification 207,562, [Class 2 (ii), Cellulose &c.], also is referred to.