GB352909A - Improved manufacture of artificial threads or films - Google Patents

Abstract

All kinds of artificial threads and films whether they be made from solutions of cellulose, cellulose esters or ethers, glue, or albuminous substances, are improved in strength by subjecting the threads and films during the process of spinning after being brought to a suitably swollen state, to an extensive stretching or drawing. The spinning may be carried out by the single bath method or by multiple bath processes. In the case of cellulose esters and ethers, the baths used may be chemically inert, for example, organic solvents; but it is possible with these and with other spinning solutions to use baths in which regeneration is at the same effected. Threads &c. of regenerated cellulose such as are obtained from viscose and from cuprammonia cellulose solutions may be swollen in strongly alkaline baths. Stretching may be carried out in the swelling bath, or after the threads &c. leave the bath; and the swelling agent may be applied as a vapour. By a suitable choice of conditions it is possible to obtain threads having a strength of 500-700 grams per 100 denier, and in the use of cellulose esters or ethers to obtain threads exhibiting a crystalline structure. It is also possible to influence the lustre of the products. If desired, the stretching may be followed by treatment with salt baths. The swelling agent contained in the threads may be converted into vapour by heat or by vacuum treatment in order to produce "air silk," the expansion that takes place during this process producing an improvement in the extensibility of the threads. The threads or films may be subjected to a mechanical treatment, preferably to a pressure treatment transversely to the direction of drawing, previous to, during or after the stretching or drawing operation. Additions for improving the plasticity, lustre, colour, &c. of the products, may be made to the spinning solution or to the swelling bath.