Hair dying methods and kits which contain a dopa species, reactive direct dye, and a ferricyanide oxidant
AssigneeClairol Incorporated
InventorsGottfried Wenke, Giuseppe Prota
Life of this patent
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Abstract
A process for dyeing hair by preparing and applying to the hair an aqueous reaction medium comprising a dopa species, a reactive direct dye and an oxidant, said aqueous reaction medium optionally containing at least one hair dyeing agent selected from the group consisting of primary intermediates and couplers and also containing a buffer to maintain the pH in the range from 6 to 10 during the reaction, and removing said aqueous reaction medium from the hair within about one hour following its preparation.
Claims25
A method of permanently dyeing hair with a melanin precursor comprising the steps of:
- (a) forming an aqueous reaction medium containing a dopa species selected from the group consisting of dopa, alpha alkyl dopa having 1 to 4 carbon atoms in the alkyl group, epinephrine and dopa alkyl esters having 1 to 6 carbon atoms in the alkyl group, a reactive direct dye that is a nitrobenzene direct dye substituted with at least one nucleophilic amino group and an oxidant selected from the group consisting of soluble ammonium, alkali metal or alkaline earth metal ferricyanide salts, each of the dopa species, reactive direct dye and oxidant being present in an amount effective to produce a reaction between the dopa species, the oxidant, and the reactive direct dye, and to produce a coloring concentration of a melanin precursor in the aqueous reaction medium, wherein a stoichiometric equivalent ratio of the dopa species to the ferricyanide oxidant is from about 0.95:1 to about 2:1, said aqueous reaction medium further containing a buffering agent in an amount sufficient to maintain the pH of aqueous reaction medium between about 6 to about 10,
- (b) contacting the hair with the aqueous reaction medium and allowing the melanin precursor to diffuse into the hair in an amount sufficient to generate a hair coloring amount of melanin, and
- (c) permanently coloring the hair by allowing the melanin precursors present in the hair to form melanin.
A hair dyeing kit for permanently dyeing hair with melanin formed from a melanin precursor which includes in a single package a plurality of containers, the kit comprising (a) a first container containing a dopa species selected from the group consisting of dopa, alpha alkyl dopa having 1 to 4 carbon atoms in the alkyl group, epinephrine and dopa alkyl esters having 1 to 6 carbon atoms in the alkyl group and a reactive direct dye that is a nitrobenzene direct dye substituted with at least one nucleophilic amino group;
- (b) a second container containing as an oxidant component a water-soluble ammonium, alkali metal or alkaline earth metal ferricyanide salt, and in one of said containers or a separate container a buffering agent selected from the group consisting of aminic buffers and ammonium and alkali metal salts of phosphates, carbonates, bicarbonates and borates, the amount of buffering agent contained in the kit being sufficient to provide a pH of from about 6 to about 10 when the contents of the container are mixed, the dopa species and oxidant component in the kit being present in a stoichiometric equivalent ratio of from about 0.95:1 to about 2:1 dopa to oxidant, and wherein each of the dopa species, reactive direct dye and oxidant are present in amounts effective to produce a reaction between the dopa species, the oxidant, and the reactive direct dye.
Dependencies are inferred from the claim text.