GB639342A - Improvements in or relating to a method for improving the strength of artificial insolubilised protein filaments - Google Patents

Abstract

Artificial filaments obtained by wet-spinning protein solutions are subjected, after coagulation, to a hardening treatment by means of formaldehyde in the presence of an acidified highly concentrated salt solution and are subsequently subjected to treatment with an aqueous solution of an ionizable mercuric salt while held under tension so as to improve their tensile strength. For the hardening treatment there may be used a solution of formaldehyde in a concentrated salt solution which has been acidified with hydrochloric or sulphuric acid, or there may be used a concentrated solution of a hydrohalide salt containing formaldehyde or a substance capable of yielding formaldehyde, a salt of a reducing sulphur acid in which the atomic proportion of oxygen, if present, to sulphur does not exceed 2 : 1, and an acid which does not oxidize the salt of the sulphur acid, and which is substantially completely ionized in dilute aqueous solution. The mercuric salt solution may be mercuric acetate solution containing acetic acid; mercuric nitrate in dilute nitric acid; mercuric chromate in water; mercuric acetate solution with sufficient caustic soda to form a basic salt. The filaments may be stretched to the maximum practical limit during the mercuric salt treatment. The wet strength may be increased by as much as 200 per cent. The treated filaments are of reduced diameter. They have reduced wet and dry elongations at break, and they have an increased weight which may be equivalent to the presence of 30 per cent of mercury. The filaments may be obtained from alkaline solutions of casein or vegetable globulins, e.g. peanut or soya bean globulins. In an example, coagulated filaments obtained from an alkaline solution of ground nut protein are hardened in a solution comprising brine, formalin, hydrochloric acid and sodium sulphide. They are washed and dried, and then stretched to a maximum in a solution containing 3 per cent of mercuric acetate and 0.1 N acetic acid at 70 DEG C. Specifications 513,910, and 533,952, are referred to.ALSO:Artificial filaments made from protein solutions and hardened by treatment with acidified saline solutions of formaldehyde, are subjected to treatment with an aqueous solution of an ionizable mercuric salt while held under tension. The treatment increases the weight of the filaments, e.g. to an extent equivalent to the presence of 30 per cent of mercury. The wet strength may be increased as much as 200 per cent. The filaments may be obtained from solutions of casein or vegetable globulins, e.g. peanut or soya bean globulins. The mercuric salt solution may be mercuric acetate solution containing acetic acid; mercuric nitrate in dilute nitric acid; mercuric chromate in water; mercuric acetate solution with sufficient caustic soda to form a basic salt. The treatment may be carried out at 70 DEG C.