GB763501A - Improvements in or relating to a method for insolubilising artificial filaments, threads, fibres and the like obtained by the spinning of solutions of proteins - Google Patents

Abstract

A process for insolubilizing a bundle of coagulated protein filaments comprises subjecting the filaments to the action of a compound which gives rise to a cyanate ion, such as urea, urea nitrate or sodium or potassium cyanate, either before or after the filaments have been treated with at least one hardening agent, impregnating the hardened filaments with a solution of formaldehyde, stretching the bundle of filaments by, for instance, 75-250 per cent, and preferably 200 per cent, heating them while stretched to dry them and then, when the filaments no longer tend to shrink, heating them further to effect insolubilization. If the filaments are to be treated with only one hardening agent, that agent is preferably formaldehyde; if more than one hardening agent is used, the preliminary hardening stage or stages may employ aluminium sulphate or a sodium polymetaphosphate and the final stage formaldehyde. The pH of the impregnating formaldehyde solution used to treat the hardened filaments may vary from 0.5-11, but preferably lies within the three ranges 0.5-2, 6.5-7.5 and 9.5-11, and the solution, which may contain 10-37 g. formaldehyde per litre, may also contain small quantities of hydrochloric acid, sodium hydroxide, sodium stannate, aluminate or borate, or ammonia or pyridine to adjust the pH to the required value. The cyanate solution is preferably of pH 4-7 and of 1-30 per cent total salt concentration and at a temperature of 50-100 DEG C. The filaments may be dried at 15-160 DEG C. and then insolubilized at 120-180 DEG C. Specifications 513,910, 533,952, 597,497, [all in Group IV], 605,830, 623,460 and 642,359 are referred to.