GB580508A - Improvements in or relating to the production of insolubilised filaments, threads, films or the like shaped products by the wet-spinning of protein solutions - Google Patents

Abstract

Artificial filaments, threads, films and the like are prepared by spinning an alkaline solution of vegetable globulin or casein into an acid saline coagulating bath, stretching the coagulated product in an aqueous swelling medium having a pH value approximating to the isoelectric point of the protein, washing in an aqueous non-solvent, non-hardening shrinking bath whilst maintaining the tension, and then treating the product without tension in an aqueous saline insolubilizing bath. The aqueous bath in which the filaments are stretched may be brought to the appropriate pH value by the addition of a weak base such as aniline or o-toluidine, the alkaline salt of a strong base with a weak acid such as sodium acetate, sodium citrate, or di-sodium hydrogen phosphate, and feebly acidic salts or weak acids such as citric acid, acetic acid, phosphoric acid, boric acid or mono-sodium hydrogen phosphate. Suitable aqueous non-solvent, non-hardening baths consist of solutions of neutral salts, or dehydrating agents such as alcohol in water. If desired, the filaments or the like may be given a preliminary stretch, e.g. in the coagulating bath or in an intermediate neutral saline bath. In an example, a solution of pea nut protein in aqueous caustic soda is extruded into a coagulating bath containing sodium sulphate and sulphuric acid, and the filaments passed through a bath containing sodium sulphate in which they are extended about one-third of their length. They are then introduced into saturated brine from which they are withdrawn, and stretched to twice their length in a bath containing 0.4 per cent of aniline. Thereafter, the filaments are held under tension for one minute in a saturated sodium chloride bath at 40 DEG C., and finally insolubilized in a bath containing formaldehyde and hydrochloric acid in saturated brine. In a second example, the filaments which have been spun and given a preliminary stretch in a sodium sulphate bath as in the first example, are introduced into a bath containing 0.4 per cent of aniline in which they are further stretched to twice their length. The filaments are then passed over successive pairs of skew rollers immersed in saturated sodium chloride solution, whilst the tension is maintained. They are then cut into staple fibre and insolubilized as before. Specifications 513,910 and 543,586 are referred to.