GB470707A - An improved process for making structures from animal tissue protein fibres, such as from animal skins, glue leather waste, flesh fibres or the like - Google Patents

Abstract

A process for preparing structures, e.g. sheets, films, filaments or similar articles from fibrous animal tissue protein material, e.g. animal skins, glue leather waste or flesh fibres consists in degrading the protein material with the aid of acidic or basic solutions, homogenizing the mixture by intensive mechanical working thereof, shaping the product and simultaneously precipitating and fixing the shaped product by treatment with a liquid bath containing an alkaline or acid precipitating agent and a tanning or hardening agent. If an acid is used to degrade the protein material, an alkaline coagulant is used and vice versa Suitable degrading or coagulating substances are for example sulphuric acid, hydrochloric acid, acid ammonium sulphate, oxalic acid, pepsin, sodium hydroxide or lime. Suitable tanning or hardening agents are common salt, formaldehyde, sodium acetate, benzoates, sulphonates, chromates, or hexamethylenetetramine in a basic precipitating bath. The latter bath gives a very intensive tanning action and hardening may be completed in two minutes. Shaping of the products is effected by nozzles, pouring funnels, pouring drums or similar appliances. From the precipitating and fixing bath, the product may be led to further baths for neutralization of the acid or base for demolishing the excess tanning agent, for bleaching, washing, dyeing or softening, and finally it is dried. Clear or opaque products, colourless or coloured may be obtained and suitable weighting substances may be incorporated. If desired further degraded natural or artificial substances, e.g. a casein degradation mass may be added to the protein mass, a substance being obtained having high elasticity and toughness and low brittleness. Viscose or some other cellulose derivative may be added to the protein mass. In an example 100 kilograms of glue leather waste (about 30--40 per cent dry substance) are treated with 6 per cent caustic soda lye until the dry content of the mass is reduced to 4,5 per cent. The mass is homogenized by intensive mechanical working in a mixer and is led into a precipitating bath through a nozzle or pouring funnel. The bath contains 5 per cent sulphuric acid and 1 per cent formaldehyde. After suitable further treatment the product is dried. In a further example a 6 per cent acid ammonium sulphate bath is prepared instead of caustic soda and the precipitation bath consists of 8 per cent soda and 1 per cent hexamethylenetetramine. Specifications 422,990, 423,017, [both in Group IX], 429,039, and 429,040 are referred to.