GB600933A - Improvements relating to protein-polyphosphates and to coatings and solutions thereof and to methods of preparing the same - Google Patents

Abstract

Protein-polyphosphate compounds (see Group IV (b)) may be dissolved in aqueous solutions of urea, and solid protein-containing products obtained therefrom by treatment with formaldehyde. The solutions may be used to provide protective coatings on surfaces, the solutions being applied to the surface and coagulated with formaldehyde.ALSO:Protein-polyphosphate compounds are prepared by treating a protein-containing material with an aqueous solution containing up to 5 per cent of an alkali metal phosphate glass or an alkali metal triphosphate or trimetaphosphate, the phosphate radical being such that, when fully neutralized by an alkali metal, the motor ratio of alkali metal oxide to P2O5 is less than 2 : 1, or a mixture of two or all of these with or without the addition of a neutral salt, an alkaline reacting salt or an alkali, the solution having a pH between 5 and 9, separating the solution from the residue, lowering the pH of the solution to between 2 and 4.5 by addition of an acidic substance to precipitate the protein - polyphosphate compound and separating the latter from the liquid. Phosphates mentioned include commercial phosphate glasses, Graham's salt and sodium tripolyphosphate Na5P3O10: an amount of the order of 15 per cent of the weight of protein is suitable. Protein-containing materials mentioned comprise sotton seed meal, soya bean meal, corn meal, oil-free copra and alfalfa; the material may be treated directly or first brought into solution by means of an aqueous solution of a neutral salt. The protein polyphosphates may be dissolved in aqueous solutions of urea, polyvalent metal salts which produce an acid reaction on hydrolysis such as those of aluminium, chromium and iron or of neutral salts such as the chlorides and sulphates of the alkali metals and alkaline earth metals, and in aqueous solutions having a pH above 6, for example, solutions of alkali metal hydroxides, carbonates and phosphates. Solid protein-containing products may be obtained from these solutions by precipitation; the urea solutions are treated with a neutral salt or formaldehyde or are heated, the polyvalent metal salt solutions and neutral salt solutions are heated and those having a pH above 6 are acidified. The solutions may be used to provide protective coatings on surfaces, the solutions being applied to the surface and coagulated; the urea solutions are allowed to dry or are treated with a dilute acid, formaldehyde or a solution of a neutral salt the polyvalent metal salt solutions and neutral salt solutions are dried or heated and the alkaline solutions are treated with an acid. The protein-polyphosphates themselves are stated to be useful in paper-sizing, foods, glues and plastics. The Specification as open to inspection under Sect. 91 is not limited to the use of a pH between 2 and 4.5 in the precipitation step. This subject-matter does not appear in the Specification as accepted.