Patent GB-610832-A (GB)
Title: Improvements in and connected with the stabilising of foam
IPC: A62D1/02
Filed: 1945-11-21
Abstract: Amino-acid metal complexes are prepared by hydrolysing, in acid or neutral aqueous solution, a sulphur-containing proteinaceous material to form an amino-acid containing both a carboxyl group and a sulphydryl group, the ratio of amino-acid nitrogen to total soluble nitrogen in the hydrolysate being in excess of 50 per cent and reacting the hydrolysate, after neutralization when necessary, with a soluble salt of iron, aluminium, manganese or cobalt.  The protein hydrolysate may be formed by acid or enzymic hydrolysis and preferably contains cysteine; the hydrolysis must be carried out in the absence of alkalies or other reagents which would attack the disulphide group of cystine or the sulphydryl group of cysteine. Suitable proteinaceous materials are human hair, wool, animal horn and "rabbits'" hair.  Preferably, the amount of polyvalent metal salt added is such that there are not less than 3 molecules of cysteine present per atom of metal.  The product comprises a solution of a complex of the metal and amino-acid compound and serves as a stabilizer for foams produced by mixing air or gas and water with a suitable foam generating agent such as that prepared by hydrolysis of proteins and is also a stabilizer for the foam-generating agent itself.  In an example, a quantity of "rabbits'" hair is digested in aqueous sulphuric acid, then neutralized with lime, filtered, the dissolved lime precipitated as the oxalate and the solution again filtered and concentrated to yield a solution containing 3 per cent nitrogen with a ratio of amino-acid nitrogen: total soluble nitrogen of 55 per cent; ferrous sulphate is added and then ammonia to adjust the pH to 7.5.  This solution is added to a foam-generating agent prepared as described in Specification 601,956.  The Specification as open to inspection under Sect. 91 relates to the preparation of the complexes by reaction of iron, aluminium, manganese or cobalt with amino-acids formed by any hydrolysis of proteinaceous material.  This subject-matter does not appear in the Specification as accepted.ALSO:Foam generating agents comprise as stabiliser an amino-acid metal complex prepared by hydrolysing a sulphur-containing proteinaceous material in acid or neutral aqueous solution to form an amino-acid containing both a carboxyl group and a sulphhydryl group, the ratio of amino-acid nitrogen to total soluble nitrogen in the hydrolysate being in excess of 50 per cent, and reacting the hydrolysate, after neutralization when necessary, with a soluble salt of iron, aluminium, manganese or cobalt (see Group IV (b)).  Mixtures of the stabiliser and the foam-generating agents obtained by hydrolysis of proteinaceous materials remain relatively free from sludging over prolonged periods of storage or on exposure to air.  In an example: a quantity of "rabbits' hair" is digested in aqueous sulphuric acid, neutralized with lime, filtered, dissolved lime precipitated as the oxalate and filtered off, the solution then concentrated, ferrous sulphate added and the pH adjusted to 7.5 with ammonia; the solution is used to stabilise a foam-generating solution prepared by hydrolysing a protein as described in Specification 601,956.  The Specification as open to inspection under Sect. 91 includes the use of the complexes prepared from amino-acid protein hydrolysates generally.  This subject-matter does not appear in the Specification as accepted.