Process for dyeing keratin materials using a direct dye and an unsaturated heterocyclic salt, and composition comprising same

1 . A method for dyeing keratin materials, comprising applying onto the keratin materials, simultaneously or separately:

(a) at least one direct dye comprising at least one of compounds (a-A) through (a-G), salts thereof, isomers thereof, solvates thereof, or mixtures thereof:

and

(b) at least one compound comprising at least one of compounds (b-1) through (b-40), optical, geometrical, or tautomeric isomers thereof, solvates thereof, or mixtures thereof:

wherein Y − represents an anionic counterion, and

wherein the at least one direct dye (a) and the at least one compound (b) are applied to the keratin materials in a total amount per gram of keratin materials effective to enhance color build-up.

2 . The method according to claim 1 , comprising applying onto the keratin materials a composition comprising the at least one direct dye (a) and the at least one compound (b), wherein the composition has a pH ranging from 3 and 13.

3 . The method according to claim 1 , comprising:

i. applying onto the keratin materials a first composition comprising the at least one direct dye (a), and subsequently applying onto the keratin materials a second composition comprising the at least one compound (b); or

ii. applying onto the keratin materials a second composition comprising the at least one compound (b), and subsequently applying onto the keratin materials a first composition comprising the at least one direct dye (a);

wherein the first composition and second composition independently have a pH ranging from 3 to 13.

4 . The method according to claim 1 , comprising applying onto the keratin materials a composition comprising the at least one direct dye (a), wherein the total amount of direct dyes ranges from 0.001% to 10% by weight, relative to the total weight of the composition.

5 . The method according to claim 1 , comprising applying onto the keratin materials a composition comprising the at least one compound (b), wherein the total amount of compound (b) ranges from 1% to 99.5% by weight, relative to the total weight of the composition.

6 . The method according to claim 1 , comprising applying onto the keratin materials a composition comprising the at least one direct dye (a), wherein the total amount of direct dyes ranges from about 0.3% to about 3% by weight, relative to the total weight of the composition.

7 . The method according to claim 1 , wherein the total amount of direct dyes is about 0.5% by weight, relative to the total weight of the composition.

8 . The method according to claim 1 , further comprising applying onto the keratin materials at least one additional direct dye other than compounds (a-A) through (a-G).

9 . The method according to claim 1 , comprising applying onto the keratin materials a composition comprising the at least one compound (b), wherein the total amount of compound (b) ranges from about 3% to about 70% by weight, relative to the total weight of the composition.

10 . The method according to claim 1 , wherein the total amount of compound (b) ranges from about 5% to about 50% by weight, relative to the total weight of the composition.

11 . The method according to claim 1 , further comprising applying onto the keratin materials at least one additional compound other than compounds (b-1) through (b-40), wherein the at least one additional compound is chosen from salts of formula (A), optical, geometrical, or tautomeric isomers thereof, solvates thereof, and mixtures thereof:

wherein in formula (A):

Het represents a 5- to 10-membered cationic unsaturated aromatic heterocyclic group comprising, besides the ammonium, from 1 to 3 heteroatoms, said heterocyclic group optionally substituted with one or more groups R′ 1 or R 2 ;

R 1 and R′ 1 , which may be identical or different, represent a linear or branched, saturated or unsaturated (C 1 -C 12 ) hydrocarbon-based group optionally substituted with one or more groups chosen from hydroxyl, amino, (C 1 -C 6 )dialkylamino, (C 1 -C 6 )alkylamino, carboxyl, carboxylate, carbamide, (C 1 -C 4 )alkoxy, —SO 3 H, sulfonate, and phenyl;

R 2 represents a hydroxyl radical, an amino radical, a linear or branched, saturated or unsaturated (C 1 -C 12 ) hydrocarbon-based group optionally substituted with one or more groups chosen from hydroxyl, amino, (C 1 -C 6 )dialkylamino, (C 1 -C 6 )alkylamino, carboxyl, carboxylate, carbamide, (C 1 -C 4 )alkoxy, —SO 3 H, sulfonate, and phenyl; and

Y − represents an anionic counterion;

with the proviso that when one of R 1 , R′ 1 , or R 2 is substituted with a carboxylate or sulfonate group, Y − is absent to ensure the electrical neutrality of the salt of formula (A).

12 . The method according to claim 1 , wherein the at least one direct dye (a) and the at least one compound (b) are present in the same composition which is applied to the keratin fibers.

13 . The method according to claim 12 , wherein the composition further comprises water and optionally at least one organic solvent.

14 . The method according to claim 13 , wherein the composition has a pH ranging from about 6 to about 9.5.

15 . The method according to claim 1 , wherein the at least one direct dye (a) and the at least one compound (b) are present in different compositions which are separately applied to the keratin fibers sequentially or simultaneously.

16 . The method according to claim 15 , comprising applying to the keratin fibers, in order:

i) a first composition comprising the at least one direct dye (a); and

ii) a second composition comprising the at least one compound (b).

17 . The method according to claim 15 , comprising applying to the keratin fibers, in order:

i) a first composition comprising the at least one compound (b); and

ii) a second composition comprising the at least one direct dye (a).

18 . The method according to claim 15 , wherein the composition comprising the at least one direct dye (a) and the composition comprising the at least one compound (b) further comprise water and optionally at least one additional component chosen from organic solvents; nonionic, anionic, cationic or amphoteric surfactants; UV-screening agents; fillers; vitamins; preserving agents, or combinations thereof.

19 . The method according to claim 12 , wherein the composition consists essentially of the at least one direct dye (a), the at least one compound (b), and optionally water.

20 . The method according to claim 1 , wherein the at least one direct dye (a) and the at least one compound (b) are applied to the keratin materials at room temperature, the keratin materials are subsequently rinsed, and then the keratin materials are dried at a temperature greater than or equal to 30° C.