GB364654A - Manufacture of filaments or the like of cellulose derivatives - Google Patents

Abstract

<PICT:0364654/IV/1> <PICT:0364654/IV/2> <PICT:0364654/IV/3> <PICT:0364654/IV/4> <PICT:0364654/IV/5> In the manufacture of artificial filaments, threads, ribbons, films, &c. in which the filaments &c. are extruded from a nozzle into an evaporative atmosphere contained in a cell or chamber, the nozzle is surrounded by a shield in the form of a cup-shaped device, tube, &c. adapted to seclude the filaments in the early stages of their formation. By secluding the filaments, evaporation of the solvent is retarded thus enabling filaments of fine deniers but of high strength to be obtained; evaporation may be further retarded by cooling the shielding device; on the other hand, conditions may be such that a substantial evaporation of solvent takes place as by the provision of heating means; or vapours of solvents, swelling agents, or non-solvents may be introduced into the secluded space for the purpose of modifying the strenth, lustre, extension, and other characteristics of the filaments &c. Or a slow current of air or vapour may be passed into or withdrawn from the device. The shielding device may be made of sheet metal or of transparent or other material such as cardboard, glass, mica, or transparent cellulose acetate sheet, or of one or more layers of metal gauze. To give access to the nozzle, the shielding device may be formed in halves or slidably mounted on the filter cradle; and it is preferably closed or substantially closed at the nozzle end, while at the exit end there may be fitted a plate having an aperture to permit the passage of the filaments. The following are typical forms of shield that may be used: a series of telescoping sections 28, Fig. 2, the upper section being supported in a slidable manner on the cradle 13; a tube 35, Figs. 5 and 6, adjustably secured to the cradle and provided with an inlet 41 and an outlet 42 connected to chambers 39, 40 having baffle plates 43; a tube 52, Fig. 8, having a number of rows of perforations 54 covered by rings 55 similarly perforated so that according to the position of the rings the interchange of atmosphere between the interior of the shield and of the cell is controlled; a tube 58, Fig. 10, is slidably mounted on the cradle, and a pipe 60 for the supply of gas or vapour through a series of nozzles, jets, or perforations passes upwardly into the open mouth of the tube. The drying of the filaments &c. is completed in the cell, the conditions in which may be adapted to the type of product desired; or the filaments leaving the shield or after a limited drying in the cell may be carried into a coagulating bath and be finally collected in a spinning pot. The coagulating baths may contain solvents or latent solvents with or without salts, sugars, &c. as described in Specifications 177,868, 179,234, [both in Class 2 (ii), Cellulose &c.], 340,324, and 343,062, or acids or acid esters as described in Specifications 334,838 and 334,853, [both in Class 2 (ii), Cellulose &c.]. The filaments and other products may be stretched when in the finished condition, or they may be treated with dilute solutions of solvents or softening agents with or without stretching, as described in Specification 359,971. The process is applicable to any solutions of cellulose acetate or other cellulose esters, or of cellulose esters suitable for dry spinning. Specifications 300,998, 326,232, [both in Class 2 (ii), Cellulose &c.], 326,461, [Class 81 (i), Disinfecting &c.], 341,057, and 341,075 also are referred to. According to the Provisional Specification the secluded zone into which the filaments &c. are extruded and in which little or no evaporation of solvent takes place, may be obtained by partitioning off a part of the cell.