GB375423A - Improvements in the production of artificial threads, films and other products by wet spinning processes from solutions of cellulose esters or ethers - Google Patents

Abstract

<PICT:0375423/IV/1> <PICT:0375423/IV/2> Artificial filaments, threads, ribbons, films, and similar products are obtained by extruding a solution of an organic derivative of cellulose into a coagulating bath and then directly subjecting the plastic product to a stretching operation, only a portion, or none of the stretching force being allowed to act on the product immediately upon extrusion. The organic derivative of cellulose may be cellulose acetate or other ester or ether of cellulose. The spinning solution may contain acetone, acetic acid, ethylene or methylene dichloride with ethyl or methyl alcohol, diacetone alcohol, ethyl lactate, diethyl tartrate, or mono- or diacetin. Spinning may be carried out at normal or raised temperature. The coagulating bath or the spinning solution is such that the material passes through a plastic state in which it is stretched. Aqueous or alcoholic diacetone alcohol, diethyl tartrate, acetin, ethyl lactate, lactic acid, dioxane, tricresyl phosphate, diethyl phthalate, methyl or ethyl alcohol, hydrocarbons, castor oil, salts, sugars, and other carbohydrates or alcohols may be employed in the coagulating bath. The restriction of the stretching force may be effected by means of rods, or rollers, or by the movement of the coagulating medium. As shown in Fig. 3, filaments extruded from nozzle 7 are coagulated in a bath 8 and while still plastic are stretched between rollers 12, 13 which rotate at different speeds. The roller 12 rotates so that little or no tension is applied to the filaments on issuing from the jet. In a modification the filaments pass round a small pulley before passing to a stretching roller. In another construction, the filaments pass through a wire or glass grid and then to a stretching roller. As shown in Fig. 4, the filaments pass through a fork tensioning device 17 and thence to a stretching roller 9. By varying the inclination of the fork 17, the ratio of the tensions applied to the filaments before and after passage through the fork may be varied. Specifications 177,868, 179,234, [Class 2 (ii), Cellulose &c.], 340,324, 340,325, 340,436, and 343,062, are referred to. The Provisional Specification includes also the application of the process to products of cellulose nitrate, and a modification in which the products after coagulation are rendered plastic by a separate treatment. Specifications 334,838, 334,853 [both in Class 2 (ii), Cellulose &c.], and 340,437, are also referred to.