GB573432A - Improvements in a process for rendering insoluble and for hardening threads, ribbons, films and other filaments obtained from aqueous solutions of proteins - Google Patents

Abstract

Artificial filaments, threads, films, and like materials obtained from aqueous solutions of proteins such as casein are rendered insoluble and hardened by subjecting them when in air-dried condition to the action of a hardening agent such as formaldehyde under conditions such that the materials are prevented from contacting with liquid water or watery solutions. The aldehyde or other hardening agent may be used in gaseous or liquid state or may be dissolved in a solvent which is not a swelling agent for the protein under treatment, e.g. a lower aliphatic alcohol, ether, ketone, or ester. Such a solvent may be anhydrous or may contain a small content of water provided that it does not have a swelling effect on the protein. A substance, which decomposes and produces an aldehyde at elevated temperature, may be added to the protein spinning solution. The dry products obtained are heated to the temperature at which the aldehyde is produced. Threads may be obtained by dry-spinning an alkaline casein solution. The air-dry threads may then be passed through an atmosphere containing formaldehyde vapour at ordinary or elevated temperature. The hardened threads are then washed. If desired, the freshly-formed threads may be neutralised and washed and then dried prior to the treatment with formaldehyde. The threads may be obtained by a wet-spinning process, in which case they are dried before they are hardened with the formaldehyde vapours. In an example, sodium caseinate fibres obtained by dry spinning are exposed in air-dry condition to the vapours from an aqueous solution of formaldehyde. The hardened fibres are then soaked in a solution containing sodium chloride, potassium aluminium alum, acetic acid, and formaldehyde. They are then rinsed and dried. In other examples, sodium caseinate fibres are treated with the vapours of benzoquinone, with liquid propionic aldehyde, with a solution of formaldehyde in methanol, with a solution of acetaldehyde in ethyl ether, with a solution of quinone in ethyl ether, or with the vapours from a solution of acetaldehyde and calcium chloride. A solution of casein in caustic soda containing polyoxymethylene dimethylether is dry spun and the filaments obtained are heated to liberate formaldehyde and to effect the hardening of the filaments. Hexamethylene tetramine may also be used as the hardening agent. Reference has been directed by the Comptroller to Specifications 495,885, 521,856 and 536,841.