GB742890A - 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

Insolubilized coagulated protein filaments are produced from a bundle of filaments, which has been produced by extruding into an acid coagulating bath a solution of a protein in an aqueous solution of urea and treating the filaments with a hardening agent, by impregnating the hardened filaments in the bundle with an acidified aqueous solution of formaldehyde, drying the bundle at below 100 DEG C. and heating it to 140-180 DEG C. until the individual filaments are insolubilized, by which is meant that, when immersed for 90 minutes in an aqueous bath containing 0.1 per cent sulphuric acid and 0.25 sodium sulphate at 97 DEG C. the filaments do not change the bath into one which shows a positive biuret reaction. The protein solution should preferably be matured for 48 to 144 hours at room temperature before being spun. The proportion of protein to urea is usually about 1 : 1. The filaments are preferably stretched, e.g. 200 per cent, after impregnation with the acidified formaldehyde solution, and dried in the stretched condition. The hardening agent is preferably formaldehyde, e.g. in the form of a saturated aqueous solution of sodium chloride or sulphate containing formaldehyde and having a pH of about 4.5. The filaments should preferably be washed nearly free from salt. The hardened filaments may be treated while still wet or after having been dried. The acidified aqueous formaldehyde solution may contain 5-37 grams of formaldehyde per 100 cc. of solution and may have a pH of 1-4. It is preferably free from salt. The bundle of filaments may be a continuously travelling tow and is preferably impregnated by padding. In an example a solution of groundnut protein in an aqueous solution of urea is spun into an aqueous solution of sulphuric acid and sodium sulphate, and the filaments are stretched in a bath of the same composition, relaxed in an aqueous solution of sodium sulphate and chloride, hardened in an aqueous bath containing 20 per cent sodium sulphate, 2.5 sodium chloride and 1.5 formaldehyde at pH 5 for 7 minutes at 50 DEG C., washed substantially free from salts and dried at 80 DEG C. The filaments are then impregnated with an aqueous solution containing 10 per cent formaldehyde (and brought to a pH of 1.5 with hydrochloric acid) and stretched 200 per cent in air. The stretched filaments are then dried in the stretched condition at 80 DEG C. and thereafter heated for 30 minutes at 160 DEG C. in the relaxed condition. Specifications 467,704, 467,812, 513,910, 533,952, 593,928, 597,497, 605,830, 623,460, 642,359, 654,513 and 742,261 are referred to.