GB690566A - Improvements in and relating to the production of regenerated keratin threads, fibres, filaments and the like - Google Patents

Abstract

Regenerated keratin threads are produced by extruding an aqueous solution of keratin which has been pretreated with peracetic acid into an aquous coagulating bath, stretching the freshly extruded thread while it is still soluble in or swellable by water and then hardening it. The pretreated keratin may be dissolved in aqueous solutions of caustic soda, ammonium hydroxide or urea. The coagulating baths are preferably aqueous salt baths of pH 6.0-9.0, but may be acid; they are preferably used at 30-60 DEG C. The stretching should usually be at least 50 per cent and preferably 100-300 per cent. Stretching may be effected in air or in a coagulating bath free from hardening agents. Alternatively the threads may be stretch-spun. The hardening bath may be of the type usual for casein threads, e.g. aqueous formaldehyde alone or preferably with one or more metal salts such as sodium, magnesium or aluminium sulphate, calcium or zinc chloride, basic chromium sulphate or zirconyl sulphate. In an example degreased wool is agitated with an aqueous solution of peracetic acid, washed and squeezed free from acid, agitated with dilute aqueous ammonium hydroxide solution and precipitated by the addition of dilute sulphuric acid. The curd is filtered off, pressed and dissolved in concentrated ammonia, and the solution is extruded into a neutral aqueous solution of magnesium and sodium sulphates. The freshly extruded thread is stretched 200 per cent while wet with coagulating bath and hardened for 2 hours at 50 DEG C. in a bath containing formaldehyde, magnesium sulphate and sodium sulphate. The thread is then insolubilized by further treatment with an aqueous solution of formaldehyde, sodium sulphate and sulphuric acid, washed in water and dried. In the other example the pretreatment of the wool is effected by adding five portions of 100 volume hydrogen peroxide and five portions of acetic anhydride alternately at intervals to a stirred mixture of wool waste and 98 per cent formic acid, so that the peracetic acid is formed in situ in a number of steps. The pretreated wool is then further processed as in the first example. Specifications 502,710 and 549,642 are referred to.ALSO:Keratin for use in the production of artificial threads (see Group IV (a)) is treated with peracetic acid, which is preferably produced in situ in a number of steps by adding hydrogen peroxide and acetic anhydride step-wise to the keratin. Suitable solvents for the treated keratin are aqueous caustic soda, ammonium hydroxide and urea solutions. In one example degreased wool is agitated for 48 hours at 20 DEG C. with a 2 per cent aqueous solution of peracetic acid. In the other example, to a stirred mixture of wool waste and 98 per cent formic acid is added 100 vol. hydrogen peroxide and acetic anhydride alternately in five equal portions at half-hour intervals. After agitation for 18 hours water is added to precipitate a curd, which is separated and purified by dispersing it in aqueous ammonium hydroxide and then acidifying the mixture. The purified material is pressed and dissolved in 0.880 specific gravity ammonium hydroxide.