GB323790A - Improvements in the manufacture or treatment of threads or filaments of organic cellulose derivatives - Google Patents

Abstract

323,790. Dreyfus, H. July 27, 1928. Yarns &c., stretching.-Filaments or threads of cellulose acetate or other organic derivatives of cellulose such as cellulose ethers, are stretched continuously while in a set elastic condition during their travel from one point to another, the threads previous to or during the stretching being treated with solvents or swelling agents or wetted with water or concentrated mineral acids. Operating in this manner the stretching, which may amount to 100 per cent or more, is distributed uniformly along the length of the threads, and the stretched materials exhibit an increased resistance to delustring and also an increased strength. The stretching may take place during a bobbin-tobobbin, hank-to-bobbin, or other winding or winding and twisting operation, or the threads may be passed round a number of stretching rollers moving with increasing peripheral speeds. As a modification, stretching may be employed continuously with the production of the filaments and threads, the latter being stretched positively after the application of the agents that facilitate stretching; or such agents may consist of residual solvent as contained in the spinning solution, but in this case the stretching must be carried out after the filaments have become set but still contain a substantial amount of solvent, say 10-20 per cent. This latter modification is conveniently carried out by stretching the threads immediately on leaving the spinning cell, for which purpose they may be passed round two or more rollers moving with increasing peripheral speeds. In cases where the agent that facilitates the stretching is applied to the threads, this may be performed by means of a spray, or by passage over a moistened roller or through the vapour of the agent, or by immersing the threads, hanks or packages in a bath of the agent. After stretching, the agent may be allowed to dry in the threads, or it may be washed off and the threads then dried; drying may be carried out with tension or in the absence of tension. Specifications 198,023 and 277,089 referred to.