Patent ID: 6361767
Filing Date: 2002-03-26
Classification: A61K,A61Q

Abstract:
Method for fixing a colorant on hair keratin fibres comprising the steps of reducing the disulphide bonds of the hair keratin with an aqueous reducing agent solution consisting of (1) phosphines or a salt thereof and a mineral or organic acid, wherein the pH of the (1) phosphines solution is in the range 2 to 10 or (2) thiols, wherein the pH of the thiols solution is in the range 6.5 to 9 by using a polyquaternary ammonium hydroxide, said reducing agent generating reactive sites only on the surface of said keratin fibres to a depth of less than 10 &mgr;m and of covalently fixing on said reactive sits at least one active colorant, said active colorant containing at least one reactive function being capable to react with said reactive sites formed on the surface of the keratin fibres.