The present invention relates to a process for dyeing and/or lightening keratin fibres, in particular human keratin fibres such as the hair, using b) one or more disulfide, thiol or protected-thiol fluorescent direct dyes and a) one or more direct dyes different from b).
The present invention also relates to a cosmetic composition comprising the dyes defined above, and also to a multi-compartment device containing said dyes.
The present invention also relates to the use of the dyes a) and b) for dyeing light or dark keratin fibres, without using additional dye different from those defined above, for conferring very chromatic, particularly visible colours on the keratin fibres.

Many people have sought for a long time to modify the colour of their hair and in particular to mask their grey hair.

It is especially known practice to dye keratin fibres, in particular human keratin fibres, with dye compositions containing oxidation dye precursors, which are generally known as oxidation bases. These oxidation bases are colourless or weakly coloured compounds, which, when combined with oxidizing products, may give rise to coloured compounds via a process of oxidative condensation.

The shades obtained with these oxidation bases may be modified by combining them with couplers or colour modifiers. The variety of molecules used as oxidation bases and couplers allows a wide range of colours to be obtained.

Another well-known method consists in obtaining "semi-permanent" dyeing by applying to the keratin fibres direct dyes, which are coloured and colouring molecules that have affinity for said fibres.

The direct dyes conventionally used are chosen from nitrobenzene, anthraquinone, nitropyridine, azo, xanthene, acridine, azine and triarylmethane direct dyes. The chemical species may be non-ionic, anionic (acidic dyes) or cationic (basic dyes). The direct dyes may also be natural dyes.

Conventional direct dyeing processes consist in applying to keratin fibres dye compositions comprising direct dyes. After application, a leave-on time is observed so as to allow the dyeing molecules to penetrate by diffusion into the fibres. On conclusion of the process, the fibres are rinsed.

In contrast with oxidation dyeing, these direct dyeing processes have a tendency to better protect the integrity of the fibres. The resulting colourings are generally chromatic, but, however, are only semi-temporary. The nature of the interactions that bind the direct dyes to the keratin fibres and their desorption from the surface and/or the core of the fibre are responsible for their weak dyeing power.

Although a wide range of colours is currently accessible, it generally proves necessary to combine three dyes of complementary colours - trichromatic principle - in order to obtain a natural shade (see, for example, WO 95/15144 and WO 95/01772). This tripartite combination does not, however, show good persistence with respect to repeated shampooing. It generally, or even systematically, induces an unaesthetic changing of the colour, which the consumer finds dissuasive.

These colourings are furthermore not sufficiently fast in the face of external agents such as light or perspiration.

Thus, there is a real need to implement processes for the direct dyeing of keratin materials, in particular of keratin fibres, in particular human keratin fibres such as the hair, which do not have the drawbacks mentioned above, i.e. which make it possible especially to lead to colourings that have good properties, especially in terms of chromaticity, power, intensity, sheen, selectivity and colour build-up, and which are persistent in particular with respect to shampooing. In addition, it is sought to obtain very chromatic, particularly visible colours while at the same time remaining aesthetic. The fluorescence, associated with these colour effects, can be particularly uniform and amplified, while at the same time remaining aesthetic, under UV radiation.

It is also sought to be able to visibly lighten dark keratin fibres without having recourse to conventional bleaching products which may damage the fibres. The fluorescence, associated with these optical lightening effects, can be particularly uniform and amplified, while at the same time remaining aesthetic, under UV radiation.

Another aim of the present invention is thus to be able to dye and/or lighten dark keratin fibres, in particular human dark keratin fibres such as the hair, preferably only with the two direct dyes a) and b) without necessarily having to add an oxidizing agent.

The applicant has discovered, surprisingly, that a process for dyeing keratin fibres using b) one or more disulfide, thiol or protected-thiol fluorescent dyes and a) one or more direct, in particular ionic, preferably cationic or anionic, dyes different from b) makes it possible to achieve the objectives set out above.

Thus, the main subject of the present invention relates to a process for dyeing keratin fibres, in particular human keratin fibres such as the hair, consisting in applying to said materials:

a) one or more in particular ionic, direct dyes; and

b) one or more disulfide, thiol or protected-thiol fluorescent direct dyes;

it being understood that a) the direct dye(s) and b) the disulfide, thiol or protected-thiol fluorescent dyes are applied to said keratin materials jointly or sequentially, and that the dyes a) and b) are distinct.

Another subject of the invention is a cosmetic composition comprising:

a) one or more in particular ionic, direct dyes;

b) one or more disulfide, thiol or protected-thiol fluorescent direct dyes;

c) optionally, one or more reducing agents, and

d) optionally, the pH of said composition being between 2 and 11 inclusive, preferably between 2.5 and 10.5 inclusive, more preferentially between 3 and 10 inclusive. The combination of the a) one or more in particular ionic, direct dye(s) and b) one or more disulfide, thiol or protected-thiol fluorescent direct dye(s) makes it possible in particular to obtain colourings which are very chromatic and particularly visible, having good colouring properties, in particular in terms of chromaticity, persistence, power, intensity, sheen and selectivity, in particular on light hair. The combination according to the invention also makes it possible to visibly lighten dark keratin fibres. Furthermore, under UV radiation, the fluorescence phenomenon associated with the colour effects is particularly marked and aesthetic.

Moreover, the colourings obtained by means of the process and the composition according to the invention show good resistance to the various attacking factors to which the hair may be subjected, such as light, bad weather, washing and perspiration. They are in particular persistent with respect to shampooing, especially after at least three shampoo washes.

A subject of the present invention is also a multi-compartment device comprising a first compartment containing one or more in particular ionic, in particular cationic or anionic, direct dye(s) a) as defined above, and a second compartment containing one or more disulfide, thiol or protected-thiol fluorescent dye(s) b) as defined above, it being understood that the dyes a) and b) are distinct.

Another subject of the invention is the use of b) disulfide, thiol or protected-thiol fluorescent direct dye(s) as defined above, combined with the a) in particular ionic, direct dye(s) different from b), for dyeing and/or lightening keratin fibres, preferably human keratin fibres, such as the hair.

The process and the composition of the invention make it possible to obtain, with the fluorescent dyes of the invention, lightening of dark keratin fibres. In particular, the process of the invention makes it possible to obtain visible lightening of keratin fibres such as the hair, which lightening is very fast with respect to shampooing, common attacking factors (sunlight, perspiration) and other hair treatments without degrading the keratin fibre.

For the purposes of the invention, the term "dark keratin fibre" is intended to mean a keratin fibre that has a numerical lightness L* in the CIE system L*a*b*, of less than or equal to 45 and preferably less than or equal to 40, given that, moreover, L* = 0 is equivalent to black and L* = 100 is equivalent to white.

For the purposes of the invention, the term "dark hair" is intended to mean hair with a tone depth of less than or equal to 6 (dark blond) and preferably less than or equal to 4 (chestnut-brown).

The lightening of hair is evaluated by the "tone depth", which characterizes the degree or level of lightening. The notion of "tone" is based on the classification of natural shades, one tone separating each shade from the shade immediately following or preceding it. This definition and the classification of natural shades are well known to hairstyling professionals and are published in the book "Sciences des traitements capillaires [Hair treatment sciences]" by Charles Zviak, 1988, published by Masson, pp. 215 and 278.

The tone depths range from 1 (black) to 10 (very light blond), one unit corresponding to one tone; the higher the figure, the lighter the shade.

An artificially dyed keratin fibre is a fibre of which the colour has been modified by a dyeing treatment, for example dyeing with direct dyes or oxidation dyes.

The lightening properties of the composition of the invention after application to dark keratin fibres, for example chestnut-brown fibres, may be achieved by reflectance:

- the fibres are irradiated with visible light in the wavelength range from 400 to 700 nanometres;

- the curves of reflectance as a function of the wavelength, for fibres treated with the composition of the invention and for untreated fibres, are then compared;

- the curve corresponding to the treated fibres should show a reflectance in the wavelength range from 450 to 700 nanometres higher than the curve corresponding to the untreated fibres.

This means that, in the wavelength range from 450 to 700 nanometres, there is at least one region in which the reflectance curve corresponding to the treated fibres is higher than the reflectance curve corresponding to the untreated fibres. The term "higher" means a difference in reflectance of at least 0.05% and preferably of at least 0.1%. This does not prevent there from being in the wavelength range from 450 to 700 nanometres at least one region in which the reflectance curve corresponding to the treated fibres is superposable, or lower than the reflectance curve corresponding to the untreated fibres.

Preferably, the wavelength at which the difference is maximal between the reflectance curve for the treated hair and that for the untreated hair is in the wavelength range from 450 to 650 nanometres and preferably in the wavelength range from 450 to 620 nanometres.

Other subjects, characteristics, aspects and advantages of the invention will emerge even more clearly on reading the description and the examples that follow.

For the purposes of the present invention and unless otherwise indicated:

• the term "direct dye" means natural and/or synthetic dyes, which are soluble in the cosmetic medium, other than oxidation dyes which absorb colour in the visible spectrum, i.e. which appear to be visually coloured; they are dyes which will diffuse superficially on the keratin fibres;

• a direct dye "bearing at least one disulfide function" is a direct dye comprising at least one disulfide bond: –S–S– between two carbon atoms ;

• a "direct dye bearing at leat one protected-thiol function" is a direct dye comprising at least one protected-thiol function -SY in which Y is a protecting group known to those skilled in the art, for instance those described in the publications "Protective

Groups in Organic Synthesis", T.W. Greene, John Wiley & Sons ed., NY, 1981 , pp.

193-217; "Protecting Groups", P. Kocienski, Thieme, 3rd ed., 2005, chap. 5; and Ullmann's Encyclopedia, "Peptide Synthesis", pp. 4-5, 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a19 157;

• a "direct dye bearing at leat one thiol function" is a direct dye comprising at least one thiol function -SY' in which Y' is i) a hydrogen atom; ii) an alkali metal; iii) an alkaline-earth metal; iv) an ammonium group: N+RaRbRgRd or a phosphonium group: P+RaRbRgRd with Ra, Rb, Rg and Rd, which may be identical or different, representing a hydrogen atom or a group (C1-C4)alkyl ;

• by way of visual colour and absorption wavelength of the direct dyes of the invention associated with said colour, mention may be made of the following colours: "yellow" = λmax > 400 nm up to 440 nm limits included, "orange" = λmax > 440 nm up to 490

nm limits included, "red"= λmax> 490 up to 520 nm limits included, "purple to violet' = λmax > 520 nm and 560 nm limits included, "violet = λmax > 560 nm to 580 nm limits included, "blue" = λmax > 580 nm up to 620 nm limits included, "blue-green" = λmax > 620 nm up to 650 nm limits included, and "green" λmax > 650 nm up to 780 nm limits included; preferably, the direct dyes a) are yellow, orange, red or blue in colour, and the fluorescent direct dyes b) are preferably yellow, orange or red in colour;

• a fluorescent direct dye "bearing a disulfide function" is a direct dye comprising one or more fluorescent chromophores as defined below, and comprising a disulfide bond: –S–S– between two carbon atoms and is preferably indirectly bonded to the chromophore(s) of the dye, i.e. between the chromophores and the –S–S– function there is at least one methylene group;

• a "direct dye bearing a protected-thiol function" is a direct dye comprising a chromophore, comprising a protected-thiol function -SY in which Y is a protecting group known to those skilled in the art, for instance those described in the publications "Protective Groups in Organic Synthesis", T.W. Greene, John Wiley & Sons ed., NY, 1981 , pp. 193-217; "Protecting Groups", P. Kocienski, Thieme, 3rd ed., 2005, chap. 5; and Ullmann's Encyclopedia, "Peptide Synthesis", pp. 4-5, 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a19 157; it being understood that said protected-thiol function is preferably indirectly bonded to the chromophore of the dye, i.e. between the chromophore and the function -SY there is at least one methylene group;

• a "direct dye bearing a thiol function" is a direct dye comprising a chromophore, and comprising a thiol function -SY' in which Y' is i) a hydrogen atom; ii) an alkali metal; iii) an alkaline-earth metal; iv) an ammonium group: N+RaRbRgRd or a phosphonium group: P+RaRbRgRd with Ra, Rb, Rg and Rd, which may be identical or different, representing a hydrogen atom or a group (C1-C4)alkyl, preferentially comprising a thiol function -SH, it being understood that said thiol function is indirectly bonded to the chromophore of the dye, i.e. between the chromophore and the function -SY' there is at least one methylene group;

• a "fluorescent chromophore" is a radical derived from a fluorescent dye, that is to say a radical derived from a molecule which absorbs light in the visible range of radiation which is visually perceptible by human beings and which appears coloured to the naked eye, i.e. which absorbs light at an absorption wavelength λabs preferably between 300 and 700 nm inclusive; said chromophore is also capable of re-emitting in the visible range at an emission wavelength λem greater than the absorption wavelength, i.e. preferably λem re-emitting between 400 and 800 nm inclusive; the difference in the absorption wavelength and emission wavelength, also called Stake's shift, is between 1 nm and 100 nm inclusive; more preferentially the fluorescent chromophores are capable of absorbing at a wavelength λabs between 420 nm and 550 nm inclusive and of re-emitting in the visible range at a wavelength λem between 470 and 600 nm inclusive;

• a "chromophore" is said to be "quaternized cationic" or "bearing a quaternized cationic group" if it comprises in its structure at least one permanent cationic charge formed from at least one quaternized nitrogen atom (ammonium) or quaternized phosphorus atom (phosphonium), preferably nitrogen;

• a group is said to be "bearing a quaternizable cationic group" when it comprises at least one tertiary amine or tertiary phosphine at the end of a hydrocarbon-based chain, preferably C1-C10 alkyl, such as -(CR'R")p-N(Ra)-Rb with R' and R", which may be identical or different, representing a hydrogen atom or a (C1-C6) alkyl group; Ra and Rb, which may be identical or different, representing a (poly)(hydroxy)(C1- C6)alkyl group or Ra and Rb form, together with the nitrogen atom that bears them, a heterocycloalkyl group such as morpholino, piperidino or piperazino; and p representing an integer between 1 and 10 inclusive; preferably, R' and R" represent a hydrogen atom, Ra and Rb represent a (C1-C4)alkyl group and p is between 2 and 5;

• the fluorescent dyes according to the invention contain one or more coloured and fluorescent chromophores as defined previously; they are particularly capable of absorbing light at a wavelength λabs between 300 and 700 nm inclusive and of re- emitting in the visible range at a greater wavelength than the absorption wavelength, in particular λem between 400 and 800 nm inclusive: the difference in the absorption wavelength and emission wavelength, also called Stake's shift, is between 1 nm and 100 nm inclusive; more preferentially, the fluorescent dyes of the invention are dyes capable of absorbing at a wavelength λabs between 420 nm and 550 nm inclusive and of re-emitting in the visible range at a wavelength λem between 470 and 600 nm inclusive;

• the chromophores are said to be "different" when they differ in their chemical structure and may be chromophores derived from different families or from the same family on condition that they have different chemical structures: for example, the chromophores may be chosen from the family of azo dyes but differ in the chemical structure of the radicals constituting them or in the respective position of these radicals;

• an "alkylene chain" represents an acyclic hydrocarbon-based divalent chain which is of C1-C20, particularly C1-C6, more particularly C1-C2 when the chain is linear; optionally substituted with one or more groups, which may be identical or different, chosen from i) hydroxyl, ii) (C1-C2)alkoxy, iii) (poly)hydroxy(C2-C4)alkoxy(di)(C1- C2)(alkyl)amino, iv) Ra-Za-C(Zb)-Zc– and v) Ra-Za-S(O)t-Zc– with Za and Zb, which may be identical or different, representing an oxygen or sulfur atom, or a group NRa', Zc representing a bond, an oxygen or sulfur atom, or a group NRa; Ra representing an alkali metal, a hydrogen atom, an alkyl group, or alternatively is absent if another part of the molecule is cationic and Ra' representing a hydrogen atom or an alkyl group and t is equal to 1 or 2; more particularly, the groups iv) are chosen from carboxylate -C(O)O- or –C(O)OMetal (Metal = alkali metal), carboxyl -C(O)-OH, guanidino H2H-C(NH2)-NH-, amidino H2H-C(NH2)-, (thio)ureo H2N-

C(O)-NH– and H2N-C(S)-NH–, aminocarbonyl -C(O)-NRa'2 or aminothiocarbonyl – C(S)-NRa'2; carbamoyl Ra'–C(O)-NRa'– or thiocarbamoyl Ra'–C(S)-NRa'– with Ra', which may be identical or different, representing a hydrogen atom or a (C1- C4)alkyl group;

• an "optionally substituted, saturated or unsaturated C1-C30 divalent hydrocarbon- based chain" represents a, particularly C1-C8, hydrocarbon-based chain optionally comprising one or more conjugated or non-conjugated double bonds p, the hydrocarbon-based chain being in particular saturated; said chain is optionally substituted with one or more identical or different groups chosen from i) hydroxyl, ii) (C1-C2)alkoxy, iii) (poly)hydroxy(C2-C4)alcoxy (di)(C1-C2) (alkyl)amino, iv) Ra-Za- C(Zb)-Zc– and v) Ra-Za-S(O)t-Zc– with Za, Zb, which may be identical or different, representing an oxygen or sulfur atom, or a group NRa', Zc representing a bond, an oxygen or sulfur atom, or a group NRa; Ra representing an alkali metal, a hydrogen atom or an alkyl group or else is absent if another part of the molecule is cationic and Ra' representing a hydrogen atom or an alkyl group and t is 1 or 2; more particularly, the groups iv) are chosen from carboxylate -C(O)O- or –C(O)OMetal (Metal = alkali metal), carboxyl –C(O)-OH, guanidino H2H-C(NH2)-NH-, amidino H2H-C(NH2)-, (thio)ureo H2N-C(O)-NH- and H2N-C(S)-NH-, aminocarbonyl -C(O)- NRa'2 or aminothiocarbonyl –C(S)-NRa'2; carbamoyl Ra'-C(O)-NRa'– or thiocarbamoyl Ra'–C(S)-NRa'– with Ra', which may be identical or different, representing a hydrogen atom or a (C1-C4)alkyl group;

• the "fluorescent dyes" according to the present invention are to be differentiated from optical brighteners. Optical brighteners, also generally known as "brighteners" or "fluorescent brighteners" or "fluorescent brightening agents" or "fluorescent whitening agents or FWA" or "whiteners" or "fluorescent whiteners", are colourless compounds, which do not impart a colour and are consequently not dyes since they do not absorb in the visible light range, but only absorb in the ultraviolet range (wavelength ranging from 200 to 400 nm) and transform the absorbed energy into fluorescent light of a longer wavelength emitted in the visible part of the spectrum in the blue range. The colour impression is then generated only by the purely fluorescent light that is predominantly blue;

• the term "(hetero)aryl' is generally intended to mean aryl and heteroaryl groups;

• the "aryr or "heteroaryl" radicals or the aryl or heteroaryl part of a radical may be substituted with at least one radical borne by a carbon atom, chosen from:

- a C1-C6 and preferably C1-C4 alkyl radical optionally substituted with one or more radicals chosen from hydroxyl, C1-C2 alkoxy, C2-C4 (poly)hydroxyalkoxy, acylamino, amino substituted with two C1-C4 alkyl radicals, which may be identical or different, optionally bearing at least one hydroxyl group, or the two radicals possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5- to 7-membered and preferably 5- or 6- membered heterocycle optionally comprising another nitrogen or non-nitrogen heteroatom;

- a halogen atom such as chlorine;

- a hydroxyl or thiol group;

- a C1-C6 alkoxy or C1-C6 alkylthio radical;

- a (poly)hydroxy(C2-C6)alkoxy radical;

- an amino radical;

- a 5- or 6-membered heterocycloalkyl radical, preferentially morpholino, piperazino, piperidino or pyrolidino, which is optionally substituted with a (C1-C4) alkyl radical, preferentially methyl;

- a 5- or 6-membered heteroaryl radical, preferentially imidazolyl, optionally substituted with a (C1-C4)alkyl radical, preferentially methyl;

- an amino radical substituted with one or two identical or different C1-C6 alkyl radicals, optionally bearing at least:

i) a hydroxyl group,

ii) an amino group optionally substituted with one or two optionally substituted C1-C3 alkyl radicals, said alkyl radicals possibly forming with the nitrogen atom to which they are attached a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle, optionally comprising at least one other nitrogen or non-nitrogen heteroatom,

iii) a quaternary ammonium group -N+R'R"R"', Y- for which R', R" and R''', which may be identical or different, represent a C1-C4 alkyl group and Y- represents an anionic counterion,

iv) or an optionally cationic 5- or 6-membered heteroaryl radical, preferentially imidazolium, optionally substituted with a (C1-C4)alkyl radical, preferentially methyl;

- an acylamino radical (-N(R)-C(O)-R') in which the R radical is a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the R' radical is a C1-C2 alkyl radical;

- a carbamoyl radical ((R)2N-C(O)-) in which the radicals R, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group;

➢ an alkylsulfonylamino radical (R'-S(O)2-N(R)-) in which the R radical represents a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the R' radical represents a C1-C4 alkyl radical, or a phenyl radical;

➢ an aminosulfonyl radical ((R)2N-S(O)2-) in which the R radicals, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group;

➢ a carboxylic radical in acid or salified form (preferably salified with an alkali metal or an ammonium, which is optionally substituted);

➢ a cyano group;

➢ a nitro or nitroso group;

➢ a polyhaloalkyl group, preferably trifluoromethyl;

• the cyclic or heterocyclic part of a non-aromatic radical may be substituted with at least one substituent chosen from the following groups:

- hydroxyl;

- C1-C4 alkoxy, C2-C4 (poly)hydroxyalkoxy;

- C1-C4 alkyl;

- alkylcarbonylamino (R-C(O)-N(R')-) in which the radical R' is a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group, and the radical R is a C1-C2 alkyl radical or an amino radical optionally substituted with one or two C1-C4 alkyl groups, which may be identical or different, themselves optionally bearing at least one hydroxyl group, said alkyl radicals possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle optionally comprising at least one other nitrogen or non-nitrogen heteroatom;

- alkylcarbonyloxy (R-C(O)-O-) in which the radical R is a C1-C4 alkyl radical or an amino group optionally substituted with one or two identical or different C1-C4 alkyl groups themselves optionally bearing at least one hydroxyl group, said alkyl radicals possibly forming with the nitrogen atom to which they are attached a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle, optionally comprising at least one other nitrogen or non-nitrogen heteroatom;

- alkoxycarbonyl (R-X1-C(O)-) in which the radical R is a C1-C4 alkoxy radical, X1 is an oxygen atom or an amino group optionally substituted with a C1-C4 alkyl group itself optionally bearing at least one hydroxyl group, said alkyl radical possibly forming with the nitrogen atom to which it is attached a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle, optionally comprising at least one other nitrogen or non-nitrogen heteroatom;

• a cyclic or heterocyclic radical, or a non-aromatic part of an aryl or heteroaryl radical, may also be substituted with one or more oxo groups;

• an "aryl" radical generally represents a monocyclic or fused or non-fused polycyclic carbon-based group comprising from 6 to 22 carbon atoms, at least one ring of which is aromatic; preferentially, the aryl radical is a phenyl, biphenyl, naphthyl, indenyl, anthracenyl or tetrahydronaphthyl;

• a "cationic heteroaryl radical" is a heteroaryl group as defined previously, which comprises an endocyclic or exocyclic cationic group;

- when the charge is endocyclic, it is included in the electron derealization via the mesomeric effect; for example, it is a pyridinium, imidazolium or indolinium group:

with R and R' being a heteroaryl substituent as defined previously and particularly a (hydroxy)(C1-C8)alkyl group, such as methyl;

- when the charge is exocyclic, it is not included in the electron derealization via the mesomeric effect; for example, it is an ammonium or phosphonium substituent R+, such as trimethylammonium, which is outside the heteroaryl, such as pyridyl, indolyl, imidazolyl or naphthalimidyl, in question:

with R being a heteroaryl substituent as defined below and R+ an ammonium RaRbRcN+-, phosphonium RaRbRcP+- or ammonium RaRbRcN+-(C1-C6)alkylamino, RaRbRcN+-(C1-C6)alkyl or RaRbRcN+-(C1-C6)alkoxy group with Ra, Rb and Rc, which may be identical or different, representing a (C1-C8)alkyl group such as methyl;

■ a "heteroaryl radical generally represents a 5- to 22-membered, monocyclic or fused or non-fused polycyclic group, comprising from 1 to 6 heteroatoms chosen from nitrogen, oxygen and sulfur, at least one ring of which is aromatic; preferentially, a heteroaryl radical is chosen from acridinyl, benzimidazolyl, benzobistriazolyl, benzopyrazolyl, benzopyridazinyl, benzoquinolyl, benzothiazolyl, benzotriazolyl, benzoxazolyl, pyridinyl, tetrazolyl, dihydrothiazolyl, imidazopyridinyl, imidazolyl, indolyl, isoquinolyl, naphthoimidazolyl, naphthoxazolyl, naphthopyrazolyl, oxadiazolyl, oxazolyl, oxazolopyridyl, phenazinyl, phenoxazolyl, pyrazinyl, pyrazolyl, pyrilyl, pyrazoyltriazyl, pyridyl, pyridinoimidazolyl, pyrrolyl, quinolyl, tetrazolyl, thiadiazolyl, thiazolyl, thiazolopyridinyl, thiazoylimidazolyl, thiopyrylyl, triazolyl, xanthylyl and the ammonium salt thereof;

• a "heterocyclic radical is a 5- to 22- membered, monocyclic or fused or non-fused polycyclic radical that may contain one or two unsaturations but is not aromatic, comprising from 1 to 6 heteroatoms chosen from nitrogen, oxygen and sulfur;

• a "heterocycloalkyl radical is a heterocyclic radical comprising at least one saturated ring;

• an "alkyi radical is a linear or branched C1 to C20, preferably C1 to C10, more preferentially C1 to C8, better still C1 to C6 and even better still C1 to C4 hydrocarbon- based radical;

• the expression "optionally substituted" applied to the alkyi radical implies that said alkyi radical may be substituted with one or more radicals chosen from the following radicals: i) hydroxyl, ii) C1-C4 alkoxy, iii) R-Z-C(X)-Y- with X, Y and Z representing an oxygen or sulfur atom or N(R'), or alternatively X and/or Z represent a bond, R and R', which may be identical or different, represent a hydrogen atom or a (C1- C6)alkyl group, preferably, X represents an oxygen atom, iv) amino optionally substituted with one or two identical or different C1-C4 alkyl radicals, said alkyl radicals possibly forming, with the nitrogen atom that bears them, a 5- to 7- membered heterocycle, optionally comprising another nitrogen or non-nitrogen heteroatom; v) a quaternary ammonium group N+R'R"R"', M- for which R', R" and R'", which may be identical or different, represent a C1-C4 alkyl group, or alternatively -N+R'R"R"' forms a 5- or 6-membered heteroaryl such as imidazolium optionally substituted with a C1-C4 alkyl group and M- represents the anionic counterion, vi) carboxyl C(O)OH, vii) carboxylate C(O)O-, M+ with M+ representing a cationic counterion such as alkali metal or alkaline-earth metal, viii) sulfonic – SO3H, ix) sulfonate –SO3-, M+ with M+ as defined previously, x) cyano and xi) a carbamoyl radical ((R)2N-C(O)-) in which R, which may be identical or different, represent a hydrogen atom or a C1 to C4 alkyl radical optionally bearing at least one hydroxyl group;

• an "alkoxy radical' is generally an alkyl-oxy radical for which the alkyl radical is a linear or branched C1 to C8 and preferentially C1 to C6 hydrocarbon-based radical;

• when the alkoxy group is optionally substituted, this implies that the alkyl group is optionally substituted as defined above;

• the term "organic or mineral acid salt" is more particularly intended to mean salts chosen from a salt derived from i) hydrochloric acid HCI, ii) hydrobromic acid HBr, iii) sulfuric acid H2SO4, iv) alkylsulfonic acids: Alk-S(O)2OH such as methanesulfonic acid and ethanesulfonic acid; v) arylsulfonic acids: Ar-S(O)2OH such as benzenesulfonic acid and toluenesulfonic acid; vi) citric acid; vii) succinic acid; viii) tartaric acid; ix) lactic acid; x) alkoxysulfinic acids: Alk-O-S(O)-OH such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H3PO4; xiii) acetic acid CH3C(O)-OH; xiv) triflic acid CF3SO3H; and xv) tetrafluoroboric acid

HBF4;

• the term "anionic counterion or anion" means an organic or mineral cosmetically acceptable anion or anionic group derived from an organic or mineral acid salt associated with the cationic charge of the dye; more particularly, the anion is chosen from: i) halides such as chloride or bromide; ii) nitrates; iii) sulfonates, including C1- C6 alkylsulfonates: Alk-S(O)2O- such as methylsulfonate or mesylate and ethylsulfonate; iv) arylsulfonates: Ar-S(O)2O- such as benzenesulfonate and toluenesulfonate or tosylate; v) carboxylates Alk-C(O)-OH with Alk representing a (C1-C6)alkyl group optionally substituted with one or more hydroxyl or carboxylate groups such as citrate; vi) succinate; vii) tartrate; viii) lactate; ix) alkyl sulfates: Alk- O-S(O)O- such as methyl sulfate and ethyl sulfate; x) aryl sulfates: Ar-O-S(O)O- such as benzene sulfate and toluene sulfate; xi) alkoxy sulfates: Alk-O-S(O)2O-

such as methoxy sulfate and ethoxy sulfate; xii) aryloxy sulfates: Ar-O-S(O)2O-, xiii) phosphates O=Ρ(ΟΗ)2-O-, O=Ρ(O-)2-ΟΗ O=P(O-)3, HO-[P(O)(O-)]w-P(O)(O-)2 with w being an integer; xiv) acetate; xv) triflate; xvi) borates such as tetrafluoroborate; xvii) sulfate S(O)2O2- or SO42-; xviii) hydrogen sulfate HSO4-; xix) carbonate; xx) hydrogen carbonate; xxi) perchlorate (ClO4-) and (xxii) dianionic mineral salts such as a zinc tetrachloride; the anionic counterion, derived from the organic or mineral acid salt, ensures the electrical neutrality of the molecule: thus, it is understood that when the anion comprises several anionic charges, then the same anion may serve for the electrical neutrality of several cationic groups in the same molecule or else may serve for the electrical neutrality of several molecules; for example, a dye which contains two cationic groups may contain either two "singly charged" anionic counterions or a "doubly charged" anionic counterion such as (O=)2S(O-)2 or O=P(O-)2-OH;

in particular, the anionic counterions are chosen from halides such as chloride, bromide, fluoride or iodide; a hydroxide; a sulfate; a hydrogen sulfate; a linear or branched C1-C6 alkyl sulfate, such as the methylsulfate or ethylsulfate ion; carbonates and hydrogen carbonates; carboxylic acid salts such as formate, acetate, citrate, tartrate and oxalate; linear or branched C1-C6 alkylsulfonates, such as the methylsulfonate ion; arylsulfonates for which the aryl part, preferably phenyl, is optionally substituted with one or more C1-C4 alkyl radicals, for instance 4- tolylsulfonate; and alkylsulfonyls such as mesylate;

• The term "cationic counterion" is intended to mean alkali metal cations, alkaline- earth metal cations or organic cations such as ammoniums, preferably the anionic counterions of the invention are chosen from alkali metals such as N+ or K+;

• The term "chemical oxidizing agent" means any oxidizing agent other than atmospheric oxygen conventionally used in the field. Thus, mention may be made of hydrogen peroxide, urea peroxide, alkali metal bromates, persalts such as perborates and persulfates, and also enzymes, among which mention may be made of peroxidases, 2-electron oxidoreductases such as uricases, and 4-electron oxygenases such as laccases; preferably, the chemical oxidizing agent is hydrogen peroxide;

• Moreover, the addition salts that may be used in the context of the invention are especially chosen from addition salts with a cosmetically acceptable base such as alkaline agents as defined below, for instance alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, aqueous ammonia, amines or alkanolamines;

• the expression "at least one" is equivalent to "one or more";

• the limits of a range of values are included in that range, in particular in the expressions "between" and "ranging from ... to ..."; and

• the expression "inclusive" for a range of values means that the limits of that range are included in the defined range.

a) The direct dyes different from the fluorescent direct dyes b)

According to one particular embodiment, the direct dye(s) a) different from b), of the invention, is (are) ionic, i.e. is (are) positively or negatively charged or zwitterionic; preferably the direct dye(s) a) of the invention is (are) chosen from cationic or anionic, more preferentially cationic, direct dyes.

According to one particular embodiment, the direct dye(s) a) are yellow, orange, red, green, violet or even blue in colour. More particularly, the dyes a) are yellow, orange or red dyes, preferably yellow or orange dyes. Preferably, the direct dyes a) are not fluorescent.

According to a first preferred embodiment of the invention, the direct dye(s) a) is (are) cationic, i.e. contain(s) at least one quaternized or quaternizable cationic chromophore or at least one chromophore bearing a quaternized or quaternizable cationic group, and not comprising a sulfonate SO3- group or carboxylate C(O)O- group.

According to one particular embodiment of the invention, the cationic direct dye(s) comprise(s) at least one quaternized cationic chromophore.

Mention may be made, as direct dyes according to the invention, of the following dyes: acridines; acridones; anthranthrones; anthrapyrimidines; anthraquinones; azines;

(poly)azos, hydrazono or hydrazones, in particular arylhydrazones; azomethines; benzanthrones; benzimidazoles; benzimidazolones; benzindoles; benzoxazoles; benzopyrans; benzothiazoles; benzoquinones; bisazines; bis-isoindolines; carboxanilides; coumarins; cyanines, such as azacarbocyanines, diazacarbocyanines, diazahemicyanines, hemicyanines or tetraazacarbocyanines; diazines; diketopyrrolopyrroles; dioxazines; diphenylamines; diphenylmethanes; dithiazines; flavonoids, such as flavanthrones and flavones; fluorindines; formazans; indamines; indanthrones; indigoids and pseudoindigoids; indophenols; indoanilines; isoindolines; isoindolinones; isoviolanthrones; lactones; (poly)methines, such as dimethines of stilbene or styryl types; naphthalimides; naphthanilides; naphtholactams; naphthoquinones; nitro, in particular nitro(hetero)aromatics; oxadiazoles; oxazines; perilones; perinones; perylenes; phenazines; phenoxazines; phenothiazines; phthalocyanines; polyenes/carotenoids; porphyrins; pyranthrones; pyrazolanthrones; pyrazolones; pyrimidinoanthrones; pyronines; quinacridones; quinolines; quinophthalones; squaranes; tetrazoliums; thiazines; thioindigos; thiopyronines; triarylmethanes or xanthenes; preferably chosen from (poly)azo, hydrazono and triarylmethane dyes.

In particular, the direct dye(s) a) of the invention are chosen from azo cationic dyes.

Mention may in particular be made of those resulting from the cationic dyes described in the Kirk-Othmer Encyclopedia of Chemical Technology, "Dyes, Azo", J. Wiley & Sons, updated on 19 April 2010. Among the azo dyes that may be used according to the invention, mention may be made of the cationic azo dyes described in patent applications WO 95/15144, WO 95/01772 and EP-714954.

According to a preferred embodiment of the invention, the direct dye(s) are chosen from cationic dyes known as "basic dyes".

Mention may be made, among the azo dyes described in the Colour Index International, 3rd edition, in particular of the following compounds:

-Basic Red 22

-Basic Red 76

-Basic Yellow 57

-Basic Brown 16

-Basic Brown 17

Among the cationic quinone dyes, those mentioned in the abovementioned Colour

Index International are suitable and, among these, mention may be made, inter alia, of the following dyes:

-Basic Blue 22

-Basic Blue 99

Among the azine dyes which are suitable, mention may be made of those listed in the

Colour Index International, for example of the following dyes:

-Basic Blue 17

-Basic Red 2.

Among the cationic triarylmethane dyes which may be used according to the invention, mention may be made, in addition to those listed in the Colour Index, of the following dyes:

-Basic Green 1

-Basic Violet 3

-Basic Violet 14

-Basic Blue 7

-Basic Blue 26.

Mention may also be made of the cationic dyes described in the documents US 5 888 252, EP 1 133 975, WO 03/029 359, EP 860 636, WO 95/01772, WO 95/15144 and EP 714 954. Mention may also be made of those listed in the encyclopaedia "The Chemistry of Synthetic Dyes" by K. Venkataraman, 1952, Academic Press, vol. 1 to 7, in the "Kirk-Othmer Encyclopedia of Chemical Technology", in the chapter "Dyes and Dye Intermediates", 1993, Wiley and Sons, and in various chapters of "Ullmann's Encyclopedia of Industrial Chemistry", 7th edition, Wiley and Sons.

According to a specific embodiment, the direct dyes are cationic azo dyes, described in EP 850 636, FR 2 788 433, EP 920 856, WO 99/48465, FR 2 757 385, EP 850 637, EP 918 053, WO 97/44004, FR 2 570 946, FR 2 285 851 , DE 2 538 363, FR 2 189 006, FR 1 560 664, FR 1 540 423, FR 1 567 219, FR 1 516 943, FR 1 221 122, DE 4 220 388, DE 4 137 005, WO 01/66646, US 5 708 151 , WO 95/01772, WO 515 144, GB 1 195 386, US 3 524 842, US 5 879 413, EP 1 062 940, EP 1 133 976, GB 738 585, DE 2 527 638, FR 2 275462, GB 1974-27645, Acta Histochem. (1978), 61(1), 48-52; Tsitologiya (1968), 10(3), 403-5; Zh. Obshch. Khim. (1970), 40(1), 195-202; Ann. Chim. (Rome) (1975), 65(5-6), 305-14 ; Journal of the Chinese Chemical Society (Taipei) (1998), 45(1), 209-211 ; Rev. Roum. Chim. (1988), 33(4), 377-83; Text. Res. J. (1984), 54(2), 105-7; Chim. Ind. (Milan) (1974), 56(9), 600-3; Khim. Tekhnol. (1979), 22(5), 548-53; Ger. Monatsh. Chem. (1975), 106(3), 643-8 ; MRL Bull. Res. Dev. (1992), 6(2), 21-7; Lihua Jianyan, Huaxue Fence (1993), 29(4), 233-4; Dyes Pigm. (1992), 19(1), 69-79; Dyes Pigm. (1989), 11 (3), 163-72.

According to another preferred embodiment of the invention, the direct dye(s) a) according to the invention are cationic and chosen from hydrazono dyes.

Preferably, the cationic direct dye(s) comprise a quaternary ammonium group; more preferentially, the cationic charge is endocyclic.

These cationic radicals are, for example, a cationic radical:

- bearing an exocyclic (di/tri)(C1-C8)alkylammonium charge, or

- bearing an endocyclic charge, such as comprising a cationic heteroaryl group chosen from: acridinium, benzimidazolium, benzobistriazolium, benzopyrazolium, benzopyridazinium, benzoquinolium, benzothiazolium, benzotriazolium, benzoxazolium, bipyridinium, bis-tetrazolium, dihydrothiazolium, imidazopyridinium, imidazolium, indolium, isoquinolium, naphthoimidazolium, naphthoxazolium, naphthopyrazolium, oxadiazolium, oxazolium, oxazolopyridinium, oxonium, phenazinium, phenooxazolium, pyrazinium, pyrazolium, pyrazoyltriazolium, pyridinium, pyridinoimidazolium, pyrrolium, pyrylium, quinolium, tetrazolium, thiadiazolium, thiazolium, thiazolopyridinium, thiazoylimidazolium, thiopyrylium, triazolium or xanthylium.

Mention may be made of the hydrazono cationic dyes of formulae (II) and (III), the azo dyes of formulae (IV) and (V) below, and also the optical and geometric isomers thereof and tautomers thereof, the organic or mineral acid or base salts thereof, and also the solvates thereof such as hydrates:

Het+-C(Ra)=N-N(Rb)-Ar, Q- Het+-N(Ra)-N=C(Rb)-Ar, Q-

(II) (III)

Het+-N=N-Ar, Q- Ar+-N=N-Ar", Q-

(IV) (V) in which formulae (II) to (V):

- Het+ represents a cationic heteroaryl radical, preferentially bearing an endocyclic cationic charge, such as imidazolium, indolium or pyridinium, optionally substituted, preferentially with at least one (C1-C8) alkyl group such as methyl;

- Ar+ represents an aryl radical, such as phenyl or naphthyl, having an exocyclic cationic charge, preferentially ammonium, particularly tri(C1-C8)alkylammonium, such as trimethylammonium;

- Ar represents an aryl group, especially phenyl, which is optionally substituted, preferentially with one or more electron-donating groups such as i) optionally substituted (C1-C8)alkyl, ii) optionally substituted (C1-C8)alkoxy, iii) (di)(C1- C8)(alkyl)amino optionally substituted on the alkyl group(s) with a hydroxyl group, iv) aryl(C1-C8)alkylamino, v) optionally substituted N-(C1-C8)alkyl-N-aryl(C1- C8)alkylamino or alternatively Ar represents a julolidine group;

- Ar" represents an optionally substituted (hetero)aryl group, such as phenyl or pyrazolyl, which are optionally substituted, preferentially by one or more (C1- C8)alkyl, hydroxyl, (di)(C1-C8)(alkyl)amino, (C1-C8)alkoxy or phenyl groups; - Ra and Rb, which may be identical or different, represent a hydrogen atom or a (C1- C8)alkyl group, which is optionally substituted, preferentially with a hydroxyl group; - or else the Ra substituent with a substituent of Het+ and/or Rb with a substituent of Ar form, together with the atoms that bear them, a (hetero)cycloalkyl; in particular, Ra and Rb represent a hydrogen atom or a (C1-C4)alkyl group optionally substituted with a hydroxyl group;

- Q- represents an organic or mineral anionic counterion, such as a halide or an alkyl sulfate.

In particular, mention may be made of the azo and hydrazono direct dyes bearing endocyclic cationic charges, of formulae (II) to (V) as defined previously, more particularly cationic direct dyes of formulae (II) to (V) bearing endocyclic cationic charges described in patent applications WO 95/15144, WO 95/01772 and EP-714954.

Preferentially, mention may be made of the following direct dyes:

and also the organic or mineral acid or base addition salts thereof, the geometrical isomers, optical isomers and tautomers thereof, and the mesomeric forms thereof, and the solvates such as hydrates;

in which formulae (II-1) and (IV-1):

- R1 represents a (C1-C4)alkyl group such as methyl;

- R2 and R3, which may be identical or different, represent a hydrogen atom or a (C1-C4)alkyl group, such as methyl; and

- R4 represents a hydrogen atom or an electron-donating group such as optionally substituted (C1-C8)alkyl, optionally substituted (C1-C8)alkoxy, or (di)(C1-C8)(alkyl)amino optionally substituted on the alkyl group(s) with a hydroxyl group; particularly, R4 is a hydrogen atom,

- Z represents a CH group or a nitrogen atom, preferentially CH,

- Q- is an anionic counterion as defined above, in particular a halide, such as chloride, or an alkyl sulfate, such as methyl sulfate or mesityl.

In particular, the dyes of formulae (II-1) and (IV-1) are chosen from Basic Red 51 , Basic Yellow 87 and Basic Orange 31 or derivatives thereof:

and also the solvates thereof such as hydrates;

with Q' being an anionic counterion as defined above, in particular a halide, such as chloride, or an alkyl sulfate, such as methyl sulfate or mesityl.

According to one variant of the invention, the cationic dye(s) a) comprise at least one quaternary ammonium radical such as those of formula (VI) below, and also the optical and geometric isomers thereof, the tautomers thereof, the organic or mineral acid or base salts thereof, and also the solvates thereof such as hydrates:

W + - [C (R c ) = C (R d )] m ' -Ar, Q- (VI)

in which formula (VI):

• W+ represents a cationic heterocyclic or heteroaryl group, particularly comprising a quaternary ammonium optionally substituted with one or more (C1-C8)alkyl groups, optionally substituted especially by one or more hydroxyl groups;

• Ar representing an aryl group such as phenyl or naphthyl, optionally substituted preferentially with i) one or more halogen atoms such as chlorine or fluorine; ii) one or more groups (C1-C8)alkyl, preferably of C1-C4 such as methyl; iii) one or more hydroxyl groups; iv) one or more (C1-C8)alkoxy groups such as methoxy; v) one or more hydroxy(C1-C8)alkyl groups such as hydroxyethyl, vi) one or more amino groups or (di)(C1-C8)alkylamino, preferably with the C1-C4 alkyl part optionally substituted with one or more hydroxyl groups, such as (di)hydroxyethylamino, vii) with one or more acylamino groups; viii) one or more heterocycloalkyl groups such as piperazinyl, piperidyl or 5- or 6-membered heteroaryl such as pyrrolidinyl, pyridyl and imidazolinyl;

• m' represents an integer between 1 and 4 inclusive, and in particular m has the value 1 or 2; more preferentially 1;

• Rc and Rd, which are identical or different, represent a hydrogen atom or an optionally substituted (C1-C8)alkyl group, preferentially of C1-C4, or alternatively Rc contiguous with W+ and/or Rd contiguous with Ar form, with the atoms that carry them, a (hetero)cycloalkyl; particularly, Rc is contiguous with W+ and they form a (hetero)cycloalkyl such as cyclohexyl;

• Q- is an organic or mineral anionic counterion as defined previously.

According to one particular embodiment of the invention, the direct dye(s) a) is (are) chosen from triarylmethanes.

In particular, the triarylmethane dye(s) of the invention may be anionic, cationic or zwitterionic, preferably cationic.

Preferably, the direct dye(s) a) of the invention are chosen from the triarylmethane dyes of formula (I):

and also the organic or mineral acid or base addition salts thereof, the geometrical isomers, optical isomers and tautomers thereof, and the mesomeric forms thereof, and the solvates such as hydrates;

in which formula (I):

■ A, B and C are identical or different, and represent a (hetero)aryl group such as phenyl which is optionally substituted,

■ represents a single bond or double bond.

The direct dyes of formula (I) can thus be catonic, anionic or zwitterionic.

According to one particularly preferred embodiment of the invention, the triaylmethane dyes are cationic.

Preferably, the triarylmethane direct dye(s) according to the invention are catonic dyes of formulae (IIa) and (II'a) below:

and also the organic or mineral acid or base addition salts thereof, the geometrical isomers, optical isomers and tautomers thereof, and the mesomeric forms thereof, and the solvates thereof such as hydrates:

in which formulae (IIa) and (II'a) below:

■ R1, R2, R3 and R4, which may be identical or different, represent a hydrogen atom or one of the following groups: (C1-C6)alkyl which is optionally substituted, preferably with a hydroxyl group; aryl such as phenyl, aryl(C1-C4)alkyl such as benzyl, heteroaryl, heteroaryl(C1-C4)alkyl, or else two groups R1, and R2, and/or R3 and R4, borne by the same nitrogen atom form, together with the nitrogen atom which bears them, an optionally substituted heterocycloalkyl group such as morpholino, piperazino or

piperidino, preferably R1, R2, R3 and R4, which may be identical or different, represent a hydrogen atom or a (C1-C4)alkyl group;

■ R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, and R16, which may be identical or different, represent a hydrogen or halogen atom, or a group chosen from i) hydroxyl, ii) thiol, iii) amino iv) (di)(C1-C4)(alkyl)amino, v) (di)arylamino such as (di)phenylamino, vi) nitro, vii) acylamino (-NR-C(O)R') in which the R radical is a hydrogen atom, a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the R' radical is a C1-C2 alkyl radical; viii) carbamoyl ((R)2N-C(O)-) in which the R radicals, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group; ix) carboxylic acid or ester, (-O-C(O)R') or (-C(O)OR'), in which the R' radical is a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the R' radical is a C1-C2 alkyl radical; x) alkyl which is optionally substituted, in particular with a hydroxyl group; xi) alkylsulfonylamino (R'SO2NR-) in which the R radical represents a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the R' radical represents a C1-C4 alkyl radical, a phenyl radical; xii) aminosulfonyl ((R)2N-SO2-) in which the R radicals, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group; xiii) (C1-C4)alkoxy; and xiv) (C1-C4)alkylthio; or else two radicals borne by two contiguous carbon atoms R5 and R6 and/or R7 and R8 and/or R9 and R10 and/or R11 and R12 and/or R13 and R14 and/or R15 and R16 form, together with the carbon atoms which bear them, an aryl or heteroaryl, preferably benzo, 6-membered fused ring, said ring possibly also being optionally substituted, preferably an unsubstituted benzo ring;

■ Q- represents an anionic counterion as defined previously, for achieving electron neutrality of the molecule, preferably chosen from halides such as chloride or bromide, and phosphate;

when the cationic dye comprises one or more anionic substituents such as COOR or SO3R with R denoting a hydrogen or a cation, it is understood that there are then more cationic substituents than anionic substituents, such that the overall resulting charge of the triarylmethane structure is cationic, counterbalanced by Q-.

Even more preferably the direct dye(s) a) of the invention are chosen formulae (IIa) and

(II'a) such as from HC Blue 15

According to one preferred embodiment, the direct dye(s) a) is (are) chosen from the triarylmethane dyes of formula (IIa) or (II'a), in which, taken alone or separately,

■ R1, R2, R3 and R4 represent a hydrogen atom or a (C1-C4)alkyl group such as methyl or ethyl;

■ R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, and R16 represent a hydrogen atom, a halogen atom, such as chlorine, or a (C1-C4)alkyl group such as methyl or ethyl, an amino group, a (di)(C1-C4)(alkyl)amino group and, preferably, at least one of the R9, R10, R11 or R12 groups represents a hydrogen atom, a halogen atom (CI), or an amino group, or a (C1-C4)(alkyl)amino or (di)(C1-C4)(alkyl)amino group, preferably in the para position with respect to the phenyl group.

Preferably, the direct dye(s) of triaylmethane structure are chosen from Basic Violet 1, Basic Violet 2, Basic Violet 3, Basic Violet 4, Basic Violet 14, Basic Blue 1, Basic Blue 7, Basic Blue 26, Basic green 1, Basic Blue 77 (also called HC Blue 15), and mixtures thereof.

According to another preferred mode of the invention, the direct dye(s) a) are chosen from anionic direct dyes.

The term "anionic direct dyes" is intended to mean any direct dye comprising in its structure at least one sulfonate SO3- group and/or at least one carboxylate group C(O)O- and optionally one or more anionic groups G- with G-, which may be identical or different, representing an anionic group chosen from alkoxide O-, thiolate S-, carboxylate and thiocarboxylate: C(Q)Q'- with Q and Q', which may be identical or different, representing an oxygen or sulfur atom; preferably G- represents a carboxylate, i.e. Q and Q' represent an oxygen atom, and not comprising a quaternized or quaternizable cationic chromophore or a chromophore bearing a quaternized or quaternizable catonic group.

In particular, the term "anionic direct dyes" is commonly intended to mean dyes referred to as "acid" direct dyes owing to their affinity with alkaline substances. The term "anionic direct dyes" means any direct dye comprising in its structure at least one CO2R or SO3R substituent with R denoting a hydrogen atom or a cation originating from a metal or an amine, or an ammonium ion.

Preferably, the anionic direct dye(s) is (are) chosen from acidic nitro direct dyes, acidic azo dyes, acidic azine dyes, acidic triarylmethane dyes, acidic indoamine dyes, acidic anthraquinone dyes, acidic indigoids and acidic natural dyes; each of these dyes having at least one sulfonate or carboxylate group bearing a cationic counterion as defined previously; preferentially alkali metal, alkaline-earth metal or ammonium sulfonate or carboxylate.

More particularly, the dye(s) of the invention are chosen from the direct dyes of formula

(A):

Col(-)m (Q+)n (A)

■ Col(-)m represents the anionic part of the anionic direct dye or "acid" dye comprising in its structure at least one sulfonate group and/or at least one carboxylate group and comprising m anionic charge(s):

■ m and n, which may be identical or different, represent an integer between 1 and 10 inclusive;

■ Q+, which may be identical or different, represents an organic or mineral cationic counterion preferably chosen from alkali metal or alkaline-earth metal cations such as Na+or K+.

In formula (A) of the invention, the radical Col(-)m represents the anionic part of the "acid dyes" or of the anionic direct dyes and preferentially Col(-)m comprises in its structure:

• at least one sulfonate group and at least one (hetero)aryl group, it being understood that at least one sulfonate group is directly connected to a (hetero)aryl group, preferentially aryl such as phenyl or benzo; and

• optionally one or more anionic groups G- as defined previously.

According to another preferred embodiment of the invention, Col(-)m comprises in its structure:

• at least one carboxylate group; and

• at least one (hetero)aryl group, it being understood that at least one carboxylate group is directly connected to a (hetero)aryl group, preferentially aryl such as phenyl or benzo; and

• optionally one or more anionic groups G- as defined previously.

According to yet another preferred embodiment of the invention Col(-)m comprises in its structure:

• at least one carboxylate group, at least one sulfonate group and at least one (hetero)aryl group, it being understood that at least one sulfonate or carboxylate group is directly connected to a (hetero)aryl group, preferentially aryl such as phenyl or benzo; and

• optionally one or more anionic groups G- as defined previously.

According to a particular embodiment of the invention, the dyes of formula (A) are such that m is equal to n.

An advantageous variant of the invention concerns the dyes of formula (A) for which m and n are equal to 1, 2 or 3.

The preferred anionic dyes of formula (A) of the invention are chosen from acidic nitro direct dyes, acidic azo dyes, acidic azine dyes, acidic triarylmethane dyes, acidic indoamine dyes, acidic anthraquinone dyes, acidic indigoids and acidic natural dyes; each of these dyes having at least one sulfonate or carboxylate group bearing a cationic counterion as defined previously; preferentially alkali metal, alkaline-earth metal or ammonium sulfonate or carboxylate.

As dyes according to the invention, mention may be made of the dyes of formulae (VII), (VII'), (VIII), (VIII'), (IX), (ΙΧ'), (X), (Χ'), (XI), (XII), (ΧΙΙ'), (XIII), and (XIV) below:

c3a) the diaryl anionic azo dyes of formula (VII) or (VII'):

in which formulae (VII) and (VII'):

• R7, R8, R9, R10, R'7, R'8, R'9 and R'10, which may be identical or different, represent a hydrogen atom or a group chosen from: i) alkyl, ii) alkoxy, iii) alkylthio, iv) hydroxyl, v) mercapto, vi) nitro, vii) R°-C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"- with R° representing a hydrogen atom or an alkyl or aryl group; X, X' and X", which may be identical or different, representing an oxygen or sulfur atom or NR with R representing a hydrogen atom or an alkyl group; viii) (O)2S(O-)-, M+ with M+ represents a cationic counterion as defined previously; ix) (O)CO--, M+ with M+ represents an organic or mineral cationic counterion preferably chosen from alkali metal or alkaline-earth metal cations such as Na+ or K+; x) R"-S(O)2-, with R" representing a hydrogen atom, an alkyl group, an aryl, (di)(alkyl)amino or aryl(alkyl)amino group; preferentially a phenylamino or phenyl group; xi) R"'-S(O)2- X'- with R'" representing an optionally substituted alkyl or aryl group, X' as defined previously; xii) (di)(alkyl)amino; xiii) aryl(alkyl)amino optionally substituted with one or more groups chosen from nitro; nitroso; (O)2S(O-)-, M+ and alkoxy with M+ as defined previously; xiv) optionally substituted heteroaryl; preferentially a benzo thiazolyl group; xv) cycloalkyl; especially cyclohexyl, xvi) Ar-N=N- with Ar representing an optionally substituted aryl group; preferentially a phenyl optionally substituted with one or more alkyl groups, (O)2S(O-)-, M+ or phenylamino;

• or alternatively two contiguous groups R7 with R8 or R8 with R9 or R9 with R10 together form a fused benzo group A'; and R'7 with R'8 or R'8 with R'9 or R'9 with R'10 together form a fused benzo group B'; with A' and B' optionally substituted with one or more groups chosen from i) nitro; ii) nitroso; iii) (O)2S(O-)-, M+; iv) hydroxyl; v) mercapto; vi) (di)(alkyl)amino; vii) R°-C(X)-X'-; viii) R°-X'-C(X)-; ix) R°-X'-C(X)- X"-; x) Ar-N=N- and xi) optionally substituted aryl(alkyl)amino; with Μ+, R°, X, X', X" and Ar as defined previously;

• W represents a sigma bond σ, an oxygen or sulfur atom, or a divalent radical i) – N(R)- with R as defined previously, or ii) methylene -C(Ra)(Rb)- with Ra and Rb, which may be identical or different, representing a hydrogen atom or an aryl group, or alternatively Ra and Rb form, together with the carbon atom that bears them, a spiro cycloalkyl; preferentially, W represents a sulfur atom or Ra and Rb together form a cyclohexyl;

it being understood that formulae (VII) and (VII') comprise at least one sulfonate (O)2S(O- )-, Q+ or carboxylate (O)C(O-)-, Q+ radical on one of the rings A, A', B, B' or C with R1R2R3R4 as defined previously; Q+ represents an organic or mineral cationic counterion preferably chosen from alkali metal or alkaline-earth metal cations such as Na+ or K+ preferentially alkali metal, alkaline-earth metal or ammonium sulfonate or carboxylate;

As examples of dyes of formula (II), mention may be made of: Acid Red 1, Acid Red 4, Acid Red 13, Acid Red 14, Acid Red 18, Acid Red 27, Acid Red 32, Acid Red 33, Acid Red 35, Acid Red 37, Acid Red 40, Acid Red 41, Acid Red 42, Acid Red 44, Acid Red 68, Acid Red 73, Acid Red 135, Acid Red 138, Acid Red 184, Food Red 1, Food Red 13, Acid Orange 6, Acid Orange 7, Acid Orange 10, Acid Orange 19, Acid Orange 20, Acid Orange 24, Acid Yellow 9, Acid Yellow 36, Acid Yellow 199, Food Yellow 3; Acid Violet 7, Acid Violet 14, Acid Blue 113, Acid Blue 117, Acid Black 1, Acid Brown 4, Acid Brown 20, Acid Black 26, Acid Black 52, Food Black 1, Food Black 2;

and as examples of dyes of formula (VII'), mention may be made of: Acid Red 111 , Acid Red 134, Acid yellow 38;

c3b) the pyrazolone anionic azo dyes of formulae (VIII) and (VIII'):

in which formulae (VIII) and (VIII'):

• R11, R12 and R13, which may be identical or different, represent a hydrogen or halogen atom, an alkyl group or -(O)2S(O-), M+ with M+ as defined previously;

• R14 represents a hydrogen atom, an alkyl group or a group -C(O)O-, M+ with M+ as defined previously;

• R15 represents a hydrogen atom;

• R16 represents an oxo group, in which case R'16 is absent, or alternatively R15 with R16 together form a double bond;

• R17 and R18, which may be identical or different, represent a hydrogen atom or a group chosen from:

- (O)2S(O-)-, M+ with M+ as defined previously;

- Ar-O-S(O)2- with Ar representing an optionally substituted aryl group, preferentially a phenyl optionally substituted with one or more alkyl groups;

• R19 and R20 together form either a double bond, or a benzo group D', which is optionally substituted;

• R'16, R'19 and R'20, which may be identical or different, represent a hydrogen atom or an alkyl or hydroxyl group;

• R21 represents a hydrogen atom or an alkyl or alkoxy group;

• Ra and Rb, which may be identical or different, are as defined previously, preferentially Ra represents a hydrogen atom and Rb represents an aryl group;

• Y represents either a hydroxyl group or an oxo group;

• - - - represents a single bond when Y is an oxo group; and represents a double bond when Y represents a hydroxyl group;

it being understood that formulae (VIII) and (VIII') comprise at least one sulfonate group (O)2S(O-)-, Q+ on one of the rings D or E or formulae (VIII) and (VIII') comprise at least one carboxylate group (O)C(O-)-, Q+ with Q+ as defined previously; preferentially comprise at least one sulfonate group (O)2S(O-)-, Q+ on one of the rings D or E and more particularly sulfonate;

As examples of dyes of formula (VIII), mention may be made of: Acid Red 195, Acid Yellow 23, Acid Yellow 27, Acid Yellow 76, and as examples of dyes of formula (VIII'), mention may be made of Acid Yellow 17;

c3c) the anthraquinone dyes of formulae (IX) and (IX'):

in which formulae (IX) and (IX'):

• R22, R23, R24, R25, R26 and R27, which may be identical or different, represent a hydrogen or halogen atom or a group chosen from i) alkyl, ii) hydroxyl, iii) mercapto, iv) alkoxy, v) alkylthio, vi) aryloxy or arylthio which is optionally substituted, preferentially substituted with one or more groups chosen from alkyl and (O)2S(O- )-, M+ with M+ as defined previously, vii) aryl(alkyl)amino optionally substituted with one or more groups chosen from alkyl and (O)2S(O-)-, M+ with M+ as defined previously, viii) (di)(alkyl)amino, ix) (di)(hydroxyalkyl)amino, x) (O)2S(O-)-, M+ with M+ as defined previously;

• Z' represents a hydrogen atom or a group NR28R29 with R28 and R29, which may be identical or different, representing a hydrogen atom or a group chosen from i) alkyl, ii) polyhydroxyalkyl such as hydroxyethyl, iii) aryl optionally substituted with one or more groups, particularly alkyl, such as methyl, n-dodecyl, n-butyl; (O)2S(O-)-, M+ with M+ as defined previously; R°-C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"- with R°, X, X' and X" as defined previously, preferentially R° represents an alkyl group, iv) cycloakyl; especially cyclohexyl;

• Z represents a group chosen from hydroxyl and NR'28R'29 with R'28 and R'29, which may be identical or different, representing the same atoms or groups as R28 and R29 as defined previously;

it being understood that formulae (IX) and (IX') comprise at least one sulfonate group (O)2S(O-)-, Q+;

As examples of dyes of formula (IX), mention may be made of: Acid Blue 25, Acid Blue 43, Acid Blue 62, Acid Blue 78, Acid Blue 129, Acid Blue 138, Acid Blue 140, Acid Blue 251 , Acid Green 25, Acid Green 41 , Acid Violet 42, Acid Violet 43, Mordant Red 3; and, as examples of dyes of formula (IX'), mention may be made of Acid Black 48;

c3d) the nitro dyes of formulae (X) and (Χ'):

in which formulae (X) and (Χ'):

• R30, R31 and R32, which may be identical or different, represent a hydrogen or halogen atom or a group chosen from i) alkyl, ii) alkoxy optionally substituted with one or more hydroxyl groups, iii) alkylthio optionally substituted with one or more hydroxyl groups, iv) hydroxyl, mercapto, v) nitro, nitroso, vi) (poly)haloalkyl, vii) R°- C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"- with R°; X, X' and X" as defined previously, viii) (O)2S(O-)-, M+ with M+ as defined previously, ix) (O)CO--, M+ with M+ as defined previously, x) (di)(alkyl)amino, xi) (di)(hydroxyalkyl)amino, xii) heterocycloalkyl such as piperidino, piperazino or morpholino; in particular, R30, R31 and R32 represent a hydrogen atom;

• Rc and Rd, which may be identical or different, represent a hydrogen atom or an alkyl group;

• W is as defined previously; W particularly represents a group -NH–;

• ALK represents a linear or branched divalent C1-C6 alkylene group; in particular, ALK represents a group -CH2-CH2-;

• n is 1 or 2;

• P represents an integer between 1 and 5 inclusive;

• q represents an integer between 1 and 4 inclusive;

• u is 0 or 1 ;

• when n is 1 , J represents a nitro or nitroso group; particularly nitro group;

• when n is 2, J represents an oxygen or sulfur atom, or a divalent radical –S(O)m– with m representing an integer 1 or 2; preferentially J represents a radical –SO2–;

• M' is as defined previously for M+;

• which may be present or absent, represents a benzo group optionally

substituted with one or more groups R30 as defined previously;

it being understood that formulae (X) and (Χ') comprise at least one sulfonate group (O)2S(O-)-, Q+ or carboxylate group (O)C(O-)-, Q+;

As examples of dyes of formula (X), mention may be made of: Acid Brown 13 and Acid Orange 3; as examples of dyes of formula (Χ'), mention may be made of: Acid Yellow 1, sodium salt of 2,4-dinitro-1-naphthol-7-sulfonic acid, 2-piperidino-5-nitrobenzenesulfonic acid, 2-(4'-N,N(2"-hydroxyethyl)amino-2'-nitro)anilineethanesulfonic acid and 4-β-hydroxyethylamino-3-nitrobenzenesulfonic acid;

c3e) the triarylmethane dyes of formula (XI):

in which formula (XI):

■ R33, R34, R35 and R36, which may be identical or different, represent a hydrogen atom or a group chosen from alkyl, optionally substituted aryl and optionally

substituted arylalkyl; particularly an alkyl group and benzyl optionally substituted with a group (O)mS(O-)-, M+ with M+ and m as defined previously;

■ R37, R38, R39, R40, R41 , R42, R43 and R44, which may be identical or different, represent a hydrogen atom or a group chosen from: i) alkyl; ii) alkoxy, alkylthio; iii) (di)(alkyl)amino; iv) hydroxyl, mercapto; v) nitro, nitroso; vii) R°-C(X)-X'-, R°-X'- C(X)-, R°-X'-C(X)-X"- with R° representing a hydrogen atom or an alkyl or aryl group; X, X' and X", which may be identical or different, representing an oxygen or sulfur atom or NR with R representing a hydrogen atom or an alkyl group; viii) (O)2S(O-)-, M+ with M+ representing a hydrogen atom or a cationic counterion; ix) O)CO--, M+ with M+ as defined previously;

■ or alternatively two contiguous groups R41 with R42 or R42 with R43 or R43 with R44 together form a fused benzo group: I'; with I' optionally substituted with one or more groups chosen from i) nitro; ii) nitroso; iii) (O)2S(O-)-, M+; iv) hydroxyl; v) mercapto; vi) (di)(alkyl)amino; vii) R°-C(X)-X'-; viii) R°-X'-C(X)-; and ix) R°-X'-C(X)-X"-; with M+, R°, X, X' and X" as defined previously;

particularly, R37 to R40 represent a hydrogen atom, and R41 to R44, which may be identical or different, represent a hydroxyl group or (O)2S(O-)-, M+; and when R43 with R44 together form a benzo group, it is preferentially substituted with a group (O)2S(O-)-; it being understood that at least one of the rings G, H, I or I' comprises at least one sulfonate (O)2S(O-)-, Q+ or carboxylate (O)C(O-)-, Q+ group;

As examples of dyes of formula (XI), mention may be made of: Acid Blue 1; Acid Blue 3; Acid Blue 7, Acid Blue 9; Acid Violet 49 and Acid Green 50;

c3f) the xanthene-based dyes of formula (XII) or (ΧII'):

in which formula (XII) or (ΧΙΙ') :

■ R45, R46, R47 and R48, which may be identical or different, represent a hydrogen or halogen atom;

■ R49, R50, R51 and R52, which may be identical or different, represent a hydrogen or halogen atom or a group chosen from i) alkyl; ii) alkoxy, alkylthio; iii) hydroxyl, mercapto; iv) nitro, nitroso; v) (O)2S(0")-, M+ with M+ representing a hydrogen atom or a cationic counterion; vi) (O)CO"-, M+ with M+ as defined previously; particularly, R53, R54, R55 and R48 represent a hydrogen or halogen atom;

■ G represents an oxygen or sulfur atom or a group NRe with Re as defined previously; particularly, G represents an oxygen atom;

■ L represents an alkoxide O-, M+; a thioalkoxide S-, M+ or a group NRf, with Rf representing a hydrogen atom or an alkyl group and M+ as defined previously; M+ is particularly Na+ or K+;

■ L' represents an oxygen or sulfur atom or an ammonium group: N+RfRg, with Rf and Rg, which may be identical or different, representing a hydrogen atom, an alkyl group or optionally substituted aryl; L' represents particularly an oxygen atom or a phenylamino group optionally substituted with one or more alkyl or (O)mS(O-)-, M+ groups with m and M+ as defined previously;

■ Q and Q', which may be identical or different, represent an oxygen or sulfur atom;

particularly Q and Q' represent an oxygen atom;

■ M+ is as defined previously ;

it being understood that formula (XII) comprises at least one sulfonate group (O)2S(O-)-, Q+ or carboxylate group (O)C(O-)-, Q+ with Q+ as defined previously;

As examples of dyes of formula (XII), mention may be made of : Acid Yellow 73; Acid Red

51; Acid Red 87; Acid Red 92; Acid Red 95 and Acid Violet 9;

As examples of formula (XII) mention may be made of Acid Red 52;

c3g) the indigoid dyes of formula (XIII):

in which formula (XIII):

■ R53, R54, R55, R56, R57, R58, R59 and R60, which may be identical or different, represent a hydrogen atom or a group chosen from: i) alkyl; ii) alkoxy, alkylthio; iii) hydroxyl, mercapto; iv) nitro, nitroso; v) R°-C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"- with R° representing a hydrogen atom or an alkyl or aryl group; X, X' and X", which may be identical or different, representing an oxygen or sulfur atom or NR with R representing a hydrogen atom or an alkyl group; vi) (O)2S(O-)-, M+ with M+ as defined previously; vii) (O)CO--, M+ with M+ as defined previously;

■ G represents an oxygen or sulfur atom or a group NRe with Re as defined previously;

particularly, G represents an oxygen atom;

■ Ri and Rh, which may be identical or different, represent a hydrogen atom or an alkyl group;

it being understood that formula (XIII) comprises at least one sulfonate group (O)2S(O-)-, Q+ or carboxylate group (O)C(O-)-, Q+ with Q+ as defined previously;

As examples of dyes of formula (XIII), mention may be made of Acid Blue 74 and indigo carmine (or indigotine I, blue CI No. 1 ) is a blue dye (number E132) which is a natural extract of the indigo plant.

c3h) the quinoline-based dyes of formula (XIV):

■ R61 represents a hydrogen or halogen atom or an alkyl group;

■ R62, R63 and R64, which may be identical or different, represent a hydrogen atom or a group (O)2S(O-)-, M+ with M+ as defined previously;

■ or alternatively R61 with R62, or R61 with R64, together form a benzo group optionally substituted with one or more groups (O)2S(O-)-, M+ with M+ representing a hydrogen atom or a cationic counterion;

it being understood that formula (IX) comprises at least one sulfonate group (O)2S(O-)-, Q+ with Q+as defined previously.

As examples of dyes of formula (IX), mention may be made of the ammonium salts derived from: Acid Yellow 2, Acid Yellow 3 and Acid Yellow 5.

More particularly, the dyes of formulae (VII) to (XIV) that are useful in the invention are chosen from the salts:

Most of these dyes are described in particular in the Colour Index published by The Society of Dyers and Colourists, P.O. Box 244, Perkin House, 82 Grattan Road, Bradford, Yorkshire, BD12 JBN England. The anionic dyes that are most particularly preferred are the dyes designated in the Colour Index under the code C.I. 58005 (monosodium salt of 1 ,2-dihydroxy-9,10-anthraquinone-3-sulfonic acid), C.I. 60730 (monosodium salt of 2- [(9,10-dihydro-4-hydroxy-9,10-dioxo-1-anthracenyl)amino]-5-methylbenzenesulfonic acid), C.I. 15510 (monosodium salt of 4-[(2-hydroxy-1-naphthalenyl)azo]benzenesulfonic acid), C.I. 15985 (disodium salt of 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonic acid), C.I. 17200 (disodium salt of 5-amino-4-hydroxy-3-(phenylazo)-2,7-naphthalenedisulfonic acid), C.I. 20470 (disodium salt of 1-amino-2-(4'-nitrophenylazo)-7-phenylazo-8-hydroxy- 3,6-naphthalenedisulfonic acid), C.I. 42090 (disodium salt of N-ethyl-N-[4-[[4-[ethyl(3- sulfophenyl)methyl]amino]phenyl](2-sulfophenyl)methylene]-2,5-cyclohexadien-1- ylidene]-3-sulfobenzenemethanaminium hydroxide, inner salt), C.I. 61570 (disodium salt of 2,2'-[(9,10-dihydro-9,10-dioxo-1,4-anthracenediyl)diimino]bis[5-methyl]benzenesulfonic acid).

The composition used according to the invention may of course comprise a mixture of dyes of formulae (VII), (VII'), (VIII), (VIII'), (IX), (ΙΧ'), (X), (Χ'), (XI), (XII), (ΧΙΙ'), (XIII), and (XIV) more preferably the anionic direct dye(s) according to the invention are chosen from those of formulae (XII') such as Acid Red 51.

It is also possible to use compounds corresponding to the mesomeric or tautomeric forms of structures (VII) to (XIV).

More particularly, the anionic direct dye(s) according to the invention are chosen from those of formulae (VII), (VIII), (IX), and (XIII), and mixtures thereof,

According to one preferred mode of the invention, the direct dye(s) a) are azo dyes of formula (IV) or (IV-1) as defined previously.

According to another preferred mode of the invention, the direct dye(s) a) are hydrazono dyes of formula (II) or (II-1) as defined previously.

According to another preferred mode of the invention, the direct dye(s) a) are triarylmethane dyes of formula (IIa) or (II'a) as defined previously, and in particular HC-blue 15.

CLAIMS

1. Process for dyeing keratin fibres, in particular human keratin fibres such as the hair, consisting in applying to said fibres:

a) one or more direct dye(s); and

b) one or more disulfide, thiol or protected-thiol direct fluorescent dye(s);

it being understood that:

- the direct dye(s) a) and the disulfide, thiol or protected-thiol fluorescent dye (s) b) are applied to said keratin fibres jointly or sequentially, and

- the dye(s) a) is (are) different from the dye(s) b).

2. Dyeing process according to the preceding claim, in which the direct dye(s) a) is (are) ionic, i.e. it (they) is (are) positively or negatively charged or is (are) zwitterionic; in particular, the direct dye(s) a) is (are) chosen from cationic direct dyes, particularly which comprise a quaternary ammonium group, the cationic charge preferably being endocyclic, and/or anionic direct dyes.

3. Dyeing process according to either one of the preceding claims, in which the direct dye(s) a) is (are) chosen from the following dyes: acridines; acridones; anthranthrones; anthrapyrimidines; anthraquinones; azines; (poly)azos, hydrazono or hydrazones, in particular arylhydrazones; azomethines; benzanthrones; benzimidazoles; benzimidazolones; benzindoles; benzoxazoles; benzopyrans; benzothiazoles; benzoquinones; bisazines; bis-isoindolines; carboxanilides; coumarins; cyanines, such as azacarbocyanines, diazacarbocyanines, diazahemicyanines, hemicyanines or tetraazacarbocyanines; diazines; diketopyrrolopyrroles; dioxazines; diphenylamines; diphenylmethanes; dithiazines; flavonoids, such as flavanthrones and flavones; fluorindines; formazans; indamines; indanthrones; indigoids and pseudoindigoids; indophenols; indoanilines; isoindolines; isoindolinones; isoviolanthrones; lactones;

(poly)methines, such as dimethines of stilbene or styryl types; naphthalimides; naphthanilides; naphtholactams; naphthoquinones; nitro, in particular nitro(hetero)aromatics; oxadiazoles; oxazines; perilones; perinones; perylenes; phenazines; phenoxazines; phenothiazines; phthalocyanines; polyenes/carotenoids; porphyrins; pyranthrones; pyrazolanthrones; pyrazolones; pyrimidinoanthrones; pyronines; quinacridones; quinolines; quinophthalones; squaranes; tetrazoliums; thiazines; thioindigos; thiopyronines; triarylmethanes or xanthenes; preferably chosen from (poly)azo, hydrazono and triarylmethane dyes.

4. Dyeing process according to any one of the preceding claims, in which the direct dye(s) a) is (are) chosen from the following direct dyes:

■ the hydrazono cationic dyes of formulae (II) and (III), the azo dyes of formulae (IV) and (V) below, and also the optical and geometric isomers thereof and tautomers thereof, the salts of organic or mineral acids or bases thereof, and also the solvates thereof such as hydrates:

Het+-C(Ra)=N-N(Rb)-Ar, Q- Het+-N(Ra)-N=C(Rb)-Ar, Q- (II) (III)

Het+-N=N-Ar, Q- Ar+-N=N-Ar", Q- (IV) (V) in which formulae (II) to (V):

- Het+ represents a cationic heteroaryl radical, preferentially bearing an endocyclic cationic charge, such as imidazolium, indolium or pyridinium, optionally substituted, preferentially with at least one (C1-C8) alkyl group such as methyl;

- Ar+ represents an aryl radical, such as phenyl or naphthyl, having an exocyclic cationic charge, preferentially ammonium, particularly tri(C1-C8)alkylammonium, such as trimethylammonium;

- Ar represents an aryl group, especially phenyl, which is optionally substituted, preferentially with one or more electron-donating groups such as i) optionally substituted (C1-C8)alkyl, ii) optionally substituted (C1-C8)alkoxy, iii) (di)(C1- C8)(alkyl)amino optionally substituted on the alkyl group(s) with a hydroxyl group, iv) aryl(C1-C8)alkylamino, v) optionally substituted N-(C1-C8)alkyl-N-aryl(C1- C8)alkylamino or alternatively Ar represents a julolidine group;

- Ar" represents an optionally substituted (hetero)aryl group, such as phenyl or pyrazolyl, which are optionally substituted, preferentially by one or more (C1- C8)alkyl, hydroxyl, (di)(C1-C8)(alkyl)amino, (C1-C8)alkoxy or phenyl groups;

- Ra and Rb, which may be identical or different, represent a hydrogen atom or a (C1- C8)alkyl group, which is optionally substituted, preferentially with a hydroxyl group; - or else the Ra substituent with a substituent of Het+ and/or Rb with a substituent of Ar form, together with the atoms that bear them, a (hetero)cycloalkyl; in particular, Ra and Rb represent a hydrogen atom or a (C1-C4)alkyl group optionally substituted with a hydroxyl group;

- Q- represents an organic or mineral anionic counterion, such as a halide or an alkyl sulfate;

particularly the direct dyes comprising azo and hydrazono endocyclic cationic charges, of formulae (II) to (V) as defined previously;

■ anionic, cationic or zwitterionic, in particular cationic, triarylmethane dyes, chosen from those of formula (I):

and also the organic or mineral acid or base addition salts thereof, the geometrical isomers, optical isomers and tautomers thereof, and the mesomeric forms thereof, and the solvates such as hydrates;

in which formula (I):

- A, B and C are identical or different, and represent a (hetero)aryl group such as phenyl which is optionally substituted, and

- represents a single bond or double bond;

preferably, the direct dye(s) a) is (are) chosen from the direct dyes (I), (II) and (IV).

5. Dyeing process according to any one of the preceding claims, in which a) the direct dye(s) a) is (are) chosen from the following direct dyes:

• the cationic azo and hydrazono dyes of formulae (II-1) and (IV-1):

and also the organic or mineral acid or base addition salts thereof, the geometrical isomers, optical isomers and tautomers thereof, and the mesomeric forms thereof, and the solvates such as hydrates;

in which formulae (II-1) and (IV-1):

- R1 represents a (C1-C4)alkyl group such as methyl;

- R2 and R3, which may be identical or different, represent a hydrogen atom or a (C1- C4)alkyl group, such as methyl; and

- R4 represents a hydrogen atom or an electron-donating group such as optionally substituted (C1-C8)alkyl, optionally substituted (C1-C8)alkoxy, or (di)(C1-C8)(alkyl)amino optionally substituted on the alkyl group(s) with a hydroxyl group; particularly, R4 is a hydrogen atom,

- Z represents a CH group or a nitrogen atom, preferentially CH,

- Q- is an anionic counterion as defined above, in particular a halide, such as chloride, or an alkyl sulfate, such as methyl sulfate or mesityl;

; and

• the cationic triarylmethanes dyes of formulae (IIa) and (II'a) below:

and also the organic or mineral acid or base addition salts thereof, the geometrical isomers, optical isomers and tautomers thereof, and the mesomeric forms thereof, and the solvates thereof such as hydrates:

in which formulae (IIa) and (II'a) below:

■ R1, R2, R3 and R4, which may be identical or different, represent a hydrogen atom or one of the following groups: (C1-C6)alkyl which is optionally substituted, preferably with a hydroxyl group; aryl such as phenyl, aryl(C1-C4)alkyl such as benzyl, heteroaryl, heteroaryl(C1-C4)alkyl, or else two groups Ri, and R2, and/or R3 and R4, borne by the same nitrogen atom form, together with the nitrogen atom which bears them, an optionally substituted heterocycloalkyl group such as morpholino, piperazino or piperidino, preferably R1, R2, R3 and R4, which may be identical or different, represent a hydrogen atom or a (C1-C4)alkyl group;

■ R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, and R16, which may be identical or different, represent a hydrogen or halogen atom, or a group chosen from i) hydroxyl, ii) thiol, iii) amino iv) (di)(C1-C4)(alkyl)amino, v) (di)arylamino such as (di)phenylamino, vi) nitro, vii) acylamino (-NR-C(O)R') in which the R radical is a hydrogen atom, a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the R' radical is a C1-C2 alkyl radical; viii) carbamoyl ((R)2N-C(O)-) in which the R radicals, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group; ix) carboxylic acid or ester, (-O-C(O)R') or (-C(O)OR'), in which the R' radical is a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the R' radical is a C1-C2 alkyl radical; x) alkyl which is optionally substituted, in particular with a hydroxyl group; xi) alkylsulfonylamino (R'SO2-NR-) in

which the R radical represents a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group and the R' radical represents a C1-C4 alkyl radical, a phenyl radical; xii) aminosulfonyl ((R)2N-SO2-) in which the R radicals, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical optionally bearing at least one hydroxyl group; xiii) (C1-C4)alkoxy; and xiv) (C1-C4)alkylthio; or else two radicals borne by two contiguous carbon atoms R5 and R6 and/or R7 and R8 and/or R9 and R10 and/or R11 and R12 and/or R13 and R14 and/or R15 and R16 form, together with the carbon atoms which bear them, an aryl or heteroaryl, preferably benzo, 6-membered fused ring, said ring possibly also being optionally substituted, preferably an unsubstituted benzo ring;

■ Q- represents an anionic counterion as defined previously, for achieving electron neutrality of the molecule, preferably chosen from halides such as chloride or bromide, and phosphate;

when the catatonic dye comprises one or more anionic substituents such as COOR or SO3R with R denoting a hydrogen or a cation, it is understood that there are then more cationic substituents than anionic substituents, such that the overall resulting charge of the triarylmethane structure is cationic, counterbalanced by Q-;

preferably the direct dye(s) a) of formulae (IIa) and (II'a) are HC Blue 15; preferably, the direct dye(s) a) is (are) chosen from the direct dyes (II-1) and (IV-1), and more particularly chosen from Basic Red 51, Basic Yellow 87 and Basic Orange 31:

and also the solvates thereof such as hydrates;

with Q' being an anionic counterion as defined in the preceding claim, in particular halide, such as chloride, or an alkyl sulfate, such as methyl sulfate or mesityl.

6. Process according to any one of the Claims 1 to 3, in which the direct dye(s) a)

(are) chosen from anionic dyes; preferably selected from those of formulae (VII), (VII'), (VIII), (VIII'), (IX), (ΙΧ'), (X), (Χ'), (XI), (XII), (ΧΙΙ'), (XIII), and (XIV) below:

c3a) the diaryl anionic azo dyes of formula (VII) or (VII'):

in which formulae (VII) and (VII'):

● R7, R8, R9, R10, R'7, R'8, R'9 and R'10, which may be identical or different, represent a hydrogen atom or a group chosen from: i) alkyl, ii) alkoxy, iii) alkylthio, iv) hydroxyl, v) mercapto, vi) nitro, vii) R°-C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"- with R° representing a hydrogen atom or an alkyl or aryl group; X, X' and X", which may be identical or different, representing an oxygen or sulfur atom or NR with R representing a hydrogen atom or an alkyl group; viii) (O)2S(O-)-, M+ with M+ represents a cationic counterion as defined previously; ix) (O)CO--, M+ with M+ represents an organic or mineral cationic counterion preferably chosen from alkali metal or alkaline-earth metal cations such as Na+ or K+; x) R"-S(O)2-, with R" representing a hydrogen atom, an alkyl group, an aryl, (di)(alkyl)amino or aryl(alkyl)amino group; preferentially a phenylamino or phenyl group; xi) R"'-S(O)2- X'- with R'" representing an optionally substituted alkyl or aryl group, X' as defined previously; xii) (di)(alkyl)amino; xiii) aryl(alkyl)amino optionally substituted with one or more groups chosen from nitro; nitroso; (O)2S(O-)-, M+ and alkoxy with M+ as defined previously; xiv) optionally substituted heteroaryl; preferentially a benzo thiazolyl group; xv) cycloalkyl; especially cyclohexyl, xvi) Ar-N=N- with Ar representing an optionally substituted aryl group; preferentially a phenyl optionally substituted with one or more alkyl groups, (O)2S(O-)-, M+ or phenylamino;

• or alternatively two contiguous groups R7 with R8 or R8 with R9 or R9 with R10 together form a fused benzo group A'; and R'7 with R'8 or R'8 with R'9 or R'9 with R'10 together form a fused benzo group B'; with A' and B' optionally substituted with one or more groups chosen from i) nitro; ii) nitroso; iii) (O)2S(O-)-, M+; iv) hydroxyl; v) mercapto; vi) (di)(alkyl)amino; vii) R°-C(X)-X'-; viii) R°-X'-C(X)-; ix) R°-X'-C(X)- X"-; x) Ar-N=N- and xi) optionally substituted aryl(alkyl)amino; with Μ+, R°, X, X', X" and Ar as defined previously;

• W represents a sigma bond σ, an oxygen or sulfur atom, or a divalent radical i) – N(R)- with R as defined previously, or ii) methylene -C(Ra)(Rb)- with Ra and Rb, which may be identical or different, representing a hydrogen atom or an aryl group, or alternatively Ra and Rb form, together with the carbon atom that bears them, a spiro cycloalkyl; preferentially, W represents a sulfur atom or Ra and Rb together form a cyclohexyl;

it being understood that formulae (VII) and (VII') comprise at least one sulfonate (O)2S(O- )-, Q+ or carboxylate (O)C(O-)-, Q+ radical on one of the rings A, A, B, B' or C with R1R2R3R4 as defined previously; Q+ represents an organic or mineral cationic counterion preferably chosen from alkali metal or alkaline-earth metal cations such as Na+or K+;

c3b) the pyrazolone anionic azo dyes of formulae (VIII) and (VIII'):

in which formulae (VIII) and (VIII'):

• R11, R12 and R13, which may be identical or different, represent a hydrogen or halogen atom, an alkyl group or -(O)2S(O-), M+ with M+ as defined previously;

• R14 represents a hydrogen atom, an alkyl group or a group -C(O)O-, M+ with M+ as defined previously;

• R15 represents a hydrogen atom;

• R16 represents an oxo group, in which case R'16 is absent, or alternatively R15 with R16 together form a double bond;

• R17 and R18, which may be identical or different, represent a hydrogen atom or a group chosen from:

- (O)2S(O-)-, M+ with M+ as defined previously;

- Ar-O-S(O)2- with Ar representing an optionally substituted aryl group, preferentially a phenyl optionally substituted with one or more alkyl groups;

• R19 and R20 together form either a double bond, or a benzo group D', which is optionally substituted;

• R'16, R'19 and R'20, which may be identical or different, represent a hydrogen atom or an alkyl or hydroxyl group;

• R21 represents a hydrogen atom or an alkyl or alkoxy group;

• Ra and Rb, which may be identical or different, are as defined previously, preferentially Ra represents a hydrogen atom and Rb represents an aryl group;

• Y represents either a hydroxyl group or an oxo group;

• - - - represents a single bond when Y is an oxo group; and represents a double bond when Y represents a hydroxyl group;

it being understood that formulae (VIII) and (VIII') comprise at least one sulfonate group (O)2S(O-)-, Q+ on one of the rings D or E or formulae (VIII) and (VIII') comprise at least one carboxylate group (O)C(O-)-, Q+ with Q+ as defined previously; preferentially comprise at least one sulfonate group (O)2S(O-)-, Q+ on one of the rings D or E and more particularly sulfonate;

c3c) the anthraquinone dyes of formulae (IX) and (IX'):

in which formulae (IX) and (IX'):

• R22, R23, R24, R25, R26 and R27, which may be identical or different, represent a hydrogen or halogen atom or a group chosen from i) alkyl, ii) hydroxyl, iii) mercapto, iv) alkoxy, v) alkylthio, vi) aryloxy or arylthio which is optionally substituted, preferentially substituted with one or more groups chosen from alkyl and (O)2S(O- )-, M+ with M+ as defined previously, vii) aryl(alkyl)amino optionally substituted with one or more groups chosen from alkyl and (O)2S(O-)-, M+ with M+ as defined previously, viii) (di)(alkyl)amino, ix) (di)(hydroxyalkyl)amino, x) (O)2S(O-)-, M+ with M+ as defined previously;

• Z' represents a hydrogen atom or a group NR28R29 with R28 and R29, which may be identical or different, representing a hydrogen atom or a group chosen from i) alkyl, ii) polyhydroxyalkyl such as hydroxyethyl, iii) aryl optionally substituted with one or more groups, particularly alkyl, such as methyl, n-dodecyl, n-butyl; (O)2S(O-)-, M+ with M+ as defined previously; R°-C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"- with R°, X, X' and X" as defined previously, preferentially R° represents an alkyl group, iv) cycloakyl; especially cyclohexyl;

• Z represents a group chosen from hydroxyl and NR'28R'29 with R'28 and R'29, which may be identical or different, representing the same atoms or groups as R28 and R29 as defined previously;

it being understood that formulae (IX) and (IX') comprise at least one sulfonate group (O)2S(O-)-, Q+;

c3d) the nitro dyes of formulae (X) and (Χ'):

in which formulae (X) and (Χ'):

• R30, R31 and R32, which may be identical or different, represent a hydrogen or halogen atom or a group chosen from i) alkyl, ii) alkoxy optionally substituted with one or more hydroxyl groups, iii) alkylthio optionally substituted with one or more hydroxyl groups, iv) hydroxyl, mercapto, v) nitro, nitroso, vi) (poly)haloalkyl, vii) R°- C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"- with R°; X, X' and X" as defined previously, viii) (O)2S(O-)-, M+ with M+ as defined previously, ix) (O)CO--, M+ with M+ as defined previously, x) (di)(alkyl)amino, xi) (di)(hydroxyalkyl)amino, xii) heterocycloalkyi such as piperidino, piperazino or morpholino; in particular, R30, R31 and R32 represent a hydrogen atom;

• Rc and Rd, which may be identical or different, represent a hydrogen atom or an alkyl group;

• W is as defined previously; W particularly represents a group -NH–;

• ALK represents a linear or branched divalent C1-C6 alkylene group; in particular, ALK represents a group -CH2-CH2-;

• n is 1 or 2;

• p represents an integer between 1 and 5 inclusive;

• q represents an integer between 1 and 4 inclusive;

• u is 0 or 1;

• when n is 1 , J represents a nitro or nitroso group; particularly nitro group;

• when n is 2, J represents an oxygen or sulfur atom, or a divalent radical –S(O)m– with m representing an integer 1 or 2; preferentially J represents a radical –SO2–;

• M' is as defined previously for M+;

■ which may be present or absent, represents a benzo group optionally

substituted with one or more groups R30 as defined previously;

it being understood that formulae (X) and (Χ') comprise at least one sulfonate group (O)2S(O-)-, Q+ or carboxylate group (O)C(O-)-, Q+;

c3e) the triarylmethane dyes of formula (XI):

in which formula (XI):

■ R33, R34, R35 and R36, which may be identical or different, represent a hydrogen atom or a group chosen from alkyl, optionally substituted aryl and optionally substituted arylalkyl; particularly an alkyl group and benzyl optionally substituted with a group (O)mS(O-)-, M+ with M+ and m as defined previously;

■ R37, R38, R39, R40, R41 R42, R43 and R44, which may be identical or different, represent a hydrogen atom or a group chosen from: i) alkyl; ii) alkoxy, alkylthio; iii) (di)(alkyl)amino; iv) hydroxyl, mercapto; v) nitro, nitroso; vii) R°-C(X)-X'-, R°-X'- C(X)-, R°-X'-C(X)-X"- with R° representing a hydrogen atom or an alkyl or aryl group; X, X' and X", which may be identical or different, representing an oxygen or sulfur atom or NR with R representing a hydrogen atom or an alkyl group; viii) (O)2S(O-)-, M+ with M+ representing a hydrogen atom or a cationic counterion; ix) O)CO--, M+ with M+ as defined previously;

■ or alternatively two contiguous groups R41 with R42 or R42 with R43 or R43 with R44 together form a fused benzo group: I'; with I' optionally substituted with one or more groups chosen from i) nitro; ii) nitroso; iii) (O)2S(O-)-, M+; iv) hydroxyl; v) mercapto; vi) (di)(alkyl)amino; vii) R°-C(X)-X'-; viii) R°-X'-C(X)-; and ix) R°-X'-C(X)-X"-; with M+, R°, X, X' and X" as defined previously;

particularly, R37 to R40 represent a hydrogen atom, and R41 to R44, which may be identical or different, represent a hydroxyl group or (O)2S(O-)-, M+; and when R43 with R44 together form a benzo group, it is preferentially substituted with a group (O)2S(O-)-; it being understood that at least one of the rings G, H, I or I' comprises at least one sulfonate (O)2S(O-)-, Q+ or carboxylate (O)C(O-)-, Q+ group;

c3f) the xanthene-based dyes of formula (XII) or (XII'):

in which formula (XII) or (ΧΙΙ') :

■ R45, R46, R47 and R48, which may be identical or different, represent a hydrogen or halogen atom;

■ R49, R50, R51 and R52, which may be identical or different, represent a hydrogen or halogen atom or a group chosen from i) alkyl; ii) alkoxy, alkylthio; iii) hydroxyl, mercapto; iv) nitro, nitroso; v) (O)2S(O-)-, M+ with M+ representing a hydrogen atom or a cationic counterion; vi) (O)CO--, M+ with M+ as defined previously; particularly, R53, R54, R55 and R48 represent a hydrogen or halogen atom;

■ G represents an oxygen or sulfur atom or a group NRe with Re as defined previously;

particularly, G represents an oxygen atom;

■ L represents an alkoxide O-, M+; a thioalkoxide S-, M+ or a group NRf, with Rf representing a hydrogen atom or an alkyl group and M+ as defined previously; M+ is particularly Na+ or K+;

■ L' represents an oxygen or sulfur atom or an ammonium group: N+RfRg, with Rf and Rg, which may be identical or different, representing a hydrogen atom, an alkyl group or optionally substituted aryl; L' represents particularly an oxygen atom or a phenylamino group optionally substituted with one or more alkyl or (O)mS(O-)-, M+ groups with m and M+ as defined previously;

■ Q and Q', which may be identical or different, represent an oxygen or sulfur atom;

particularly Q and Q' represent an oxygen atom;

■ M+ is as defined previously ;

it being understood that formula (XII) comprises at least one sulfonate group (O)2S(O-)-, Q+ or carboxylate group (O)C(O-)-, Q+ with Q+ as defined previously;

c3g) the indigoid dyes of formula (XIII):

in which formula (XIII):

■ R53, R54, R55, R56, R57, R58, R59 and R60, which may be identical or different, represent a hydrogen atom or a group chosen from: i) alkyl; ii) alkoxy, alkylthio; iii) hydroxyl, mercapto; iv) nitro, nitroso; v) R°-C(X)-X'-, R°-X'-C(X)-, R°-X'-C(X)-X"- with R° representing a hydrogen atom or an alkyl or aryl group; X, X' and X", which may be identical or different, representing an oxygen or sulfur atom or NR with R representing a hydrogen atom or an alkyl group; vi) (O)2S(O-)-, M+ with M+ as defined previously; vii) (O)CO--, M+ with M+ as defined previously;

■ G represents an oxygen or sulfur atom or a group NRe with Re as defined previously;

particularly, G represents an oxygen atom;

■ Ri and Rh, which may be identical or different, represent a hydrogen atom or an alkyl group;

it being understood that formula (XIII) comprises at least one sulfonate group (O)2S(O-)-, Q+ or carboxylate group (O)C(O-)-, Q+ with Q+ as defined previously;

c3h) the quinoline-based dyes of formula (XIV):

■ R61 represents a hydrogen or halogen atom or an alkyl group;

■ R62, R63 and R64, which may be identical or different, represent a hydrogen atom or a group (O)2S(O-)-, M+ with M+ as defined previously;

■ or alternatively R61 with R62, or R61 with R64, together form a benzo group optionally substituted with one or more groups (O)2S(O-)-, M+ with M+ representing a hydrogen atom or a cationic counterion;

it being understood that formula (IX) comprises at least one sulfonate group (O)2S(O-)-, Q+ with Q+as defined previously ;

more preferably the anionic direct dye(s) are chosen from those of formulae (XI Γ) such as Acid Red 51.

7. Dyeing process according to any one of the preceding claims, in which a) the direct dye(s) a) is (are) neither a direct dye bearing at least one disulfide function, nor a direct dye bearing at least one thiol function, nor a direct dye bearing at least one protected-thiol function.

8. Dyeing process according to any one of the preceding claims, in which the direct dye(s) a) is (are) in a cosmetic composition, in a total amount of between 0.0001% and

30% inclusive, relative to the total weight of the composition which contains it (them), in particular the total amount of direct dye(s) a) as defined in any one of the preceding claims is between 0.002% and 5% by weight inclusive, relative to the total weight of the composition which contains it (them), preferentially in a total amount of between 0.005% and 2% inclusive, relative to the total weight of the composition which comprises it (them).

9. Process according to any one of the preceding claims, in which the disulfide, thiol or protected-thiol dye(s) b) is (are) chosen from dyes which absorb light in the yellow, orange and red, particularly red, range, preferably in the absorption wavelength λabs between 400 nm and 500 nm inclusive.

10. Process according to either one of the preceding claims, in which the disulfide, thiol or protected-thiol fluorescent dye(s) b) is (are) chosen from those of formula (Ib): A – (X)p – Csat – S – U and also the organic or mineral acid or base salts thereof, the optical and geometric isomers and tautomers thereof and the solvates thereof such as hydrates, in which formula (Ib):

• U represents a radical chosen from:

a) – S – C'sat – (Χ')p' – A'; and

b) – Y;

• A and A', which may be identical or different, represent a radical containing at least one quaternized cationic fluorescent chromophore or at least one fluorescent chromophore bearing a quaternized or quaternizable cationic group;

• Y represents i) a hydrogen atom; or ii) a thiol-function-protecting group, in particular hydrogen;

• X and X', which may be identical or different, represent a linear or branched, saturated or unsaturated divalent C1-C30 hydrocarbon-based chain, optionally

interrupted and/or optionally terminated at one or both of its ends with one or more divalent groups or combinations thereof chosen from:

➢ –N(R)-, -N+(R)(R)-, -O-, -S-, -C(O)-, -S(O)- and -SO2-, with R, which may be identical or different, chosen from a hydrogen and a C1-C4 alkyl, hydroxyalkyl or aminoalkyl radical;

➢ an aromatic or non-aromatic, saturated or unsaturated, fused or non-fused (hetero)cyclic radical optionally comprising one or more identical or different, optionally substituted heteroatoms;

• p and p', which may be identical or different, are equal to 0 or 1;

• Csat and C'sat, which may be identical or different, represent an optionally substituted linear or branched, or cyclic, C1-C18 alkylene chain;

preferably, the dyes (Ib) are disulfide dyes, i.e. for which U represents the following radical a) –S–C'sat–(X')p'–A', and more particularly the dyes of formula (Ib) are symmetrical i.e. are such that A = A', Csat = C'sat, X = X' and p = p'.

11. Process according to any one of the preceding claims, in which the fluorescent dye(s) of formula (Ib) are dyes which, when p and/or p' is equal to 1, X and/or X', which may be identical or different, represent the following sequence: -(T)t-(Z)z-(T')t'- said sequence being bonded in formula (Ib) symmetrically as follows: - Csat (or C'sat)-(T)t-(Z)z-(A or A'); in which:

• T and T', which may be identical or different, represent one or more radicals or combinations thereof chosen from: –O–; -S-; -N(R)-; -N+(R)(R°)-; -S(O)-; -S(O)2-; - C(O)-; with R, R°, which may be identical or different, representing a hydrogen atom, a C1-C4 alkyl radical, C1-C4 hydroxyalkyl radical or an aryl(C1-C4)alkyl radical; and a cationic or non-cationic, preferentially monocyclic heterocycloalkyl or heteroaryl radical, preferentially containing two heteroatoms (more preferentially two nitrogen atoms) and preferentially being 5- to 7-membered, more preferentially imidazolium;

the indices t and t', which may be identical or different, are equal to 0 or 1;

• Z represents:

➢ -(CH2)m- with m an integer between 1 and 8;

➢ -(CH2CH2O)q- or -(OCH2CH2)q- in which q is an integer between 1 and 5 inclusive;

➢ an aryl, alkylaryl or arylalkyl radical in which the alkyl radical is C1-C4 and the aryl radical is preferably C6, being optionally substituted with at least one group SO3M with M representing a hydrogen atom, an alkali metal or an

ammonium group substituted with one or more identical or different, linear or branched C1-C18 alkyl radicals optionally bearing at least one hydroxyl;

• z is equal to 0 or 1.

12. Process according to either one of Claims 10 and 11, in which the disulfide, thiol or protected-thiol fluorescent dye(s) (Ib) is (are) such that A and/or A' is (are) chosen from chromophores derived from (poly)methine or naphthalimide fluorescent dyes; and preferably chosen from those:

➢ of formulae (IIb) and (IIIb) below:

W+-[C(Rc)=C(Rd)]m'–Ar,–(*) Q- Ar-[C(Rd)=C(Rc)]m'–W,+–(*) Q-

(IIb) (IIIb)

with, in formula (IIb) or (IIIb):

• W+ representing a cationic heterocyclic or heteroaryl group, particularly comprising a quaternary ammonium optionally substituted with one or more (C1-C8)alkyl groups optionally substituted especially with one or more hydroxyl groups;

• W,+ representing a divalent heterocyclic or heteroaryl radical as defined for W+;

• Ar Ar representing an aryl group such as phenyl or naphthyl, optionally substituted preferentially with i) one or more halogen atoms such as chlorine or fluorine; ii) one or more groups (C1-C8)alkyl, preferably of C1-C4 such as methyl; iii) one or more hydroxyl groups; iv) one or more (C1-C8)alkoxy groups such as methoxy; v) one or more hydroxy(C1-C8)alkyl groups such as hydroxyethyl, vi) one or more amino or (di)(C1-C8)alkylamino groups, preferably with the C1-C4 alkyl part optionally substituted with one or more hydroxyl groups, such as (di)hydroxyethylamino, vii) with one or more acylamino groups; viii) one or more heterocycloalkyl groups such as piperazinyl, piperidinyl or 5- or 6-membered heteroaryl such as pyrrolidinyl, pyridinyl and imidazolinyl;

• Ar' is an arylene radical, i.e. divalent aryl radical, as defined for Ar;

• m' represents an integer between 1 and 4 inclusive, and in particular m has the value 1 or 2; more preferentially 1 ;

• Rc, Rd, which may be identical or different, represent a hydrogen atom or an optionally substituted group (C1-C8)alkyl, preferentially of C1-C4, or alternatively Rc contiguous with W+ or W'+ and/or Rd contiguous with Ar or Ar' form, with the atoms that bear them, a (hetero)cycloalkyl, particularly Rc is contiguous with W+ or W'+ and forms a (hetero)cycloalkyl such as cyclohexyl;

• Q- is an organic or mineral anionic counterion as defined previously;

• (*) represents the part of the chromophore bonded to the rest of formula (Ib) ;

preferably, W+ or W'+ is an imidazolium, pyridinium, benzimidazolium, pyrazolium, benzothiazolium or quinolinium radical optionally substituted with one or more identical or different C1-C4 alkyl radicals; preferably, the fluorescent chromophore(s) are chosen from those with m' = 1 , Ar representing a phenyl group substituted para to the styryl group -C(Rd)=C(Rc)- with a (di)(hydroxy)(C1-C6)(alkyl)amino group such as dihydroxy(C1-C4)alkylamino, and W'+ representing an imidazolium or pyridinium group, preferably ortho- or para-pyridinium;

➢ of formula (IVb) or (Vb):

in which formulae (IVb) and (Vb):

• Re, Rf, Rg, and Rh, which may be identical or different, represent a hydrogen atom or a C1-C6 alkyl group which is optionally substituted, preferentially with a di(C1- C6)alkylamino or tri(C1-C6)alkylammonium group such as trimethylammonium;

•
representing the bond which bonds the naphthalimidyl radical to the rest of the molecule via X or X', if p = 1 or p' = 1 or else via Csat or Csat' if p = 0 or p'=0.

13. Process according to any one of the preceding claims, in which the disulfide, thiol or protected-thiol fluorescent dye(s) b) is (are) chosen from the dyes of formulae (VIb) to (Xb') below:

and also the organic or mineral acid or base salts thereof, the optical and geometric isomers and tautomers thereof, and the solvates thereof such as hydrates;

in which formulae (VIb) to (Xb'):

• G and G', which may be identical or different, represent a group -NRcRd, -NR'cR'd or C1-C6 alkoxy which is optionally substituted, preferentially unsubstituted; preferentially, G and G' represent a group -NRcRd or -NR'cR'd, respectively;

• Ra and R'a, which may be identical or different, represent an aryl(C1-C4)alkyl group or a C1-C6 alkyl group optionally substituted with a hydroxyl or amino, C1-C4 alkylamino or C1-C4 dialkylamino group, said alkyl radicals possibly forming, with the nitrogen atom that bears them, a 5- to 7-membered heterocycle, optionally comprising another nitrogen or non-nitrogen heteroatom; preferentially, Ra and R'a represent a C1-C3 alkyl group optionally substituted with a hydroxyl group, or a benzyl group;

• Rb and R'b, which may be identical or different, represent a hydrogen atom, an aryl(C1-C4)alkyl group or a C1-C6 alkyl group that is optionally substituted; preferentially, Rb and R'b represent a hydrogen atom or a C1-C3 alkyl or benzyl group;

• Rc, R'c, Rd and R'd, which may be identical or different, represent a hydrogen atom, an aryl(C1-C4)alkyl or C1-C6 alkoxy group or a C1-C6 alkyl group that is optionally substituted; Rc, R'c, Rd and R'd preferentially represent a hydrogen atom, a hydroxyl, C1-C3 alkoxy, amino or C1-C3 (di)alkylamino group, or a C1-C3 alkyl group that is optionally substituted with i) a hydroxyl group, ii) amino, iii) C1-C3 (di)alkylamino, or iv) quaternary ammonium (R")(R"')(R"")N+-;

or alternatively two adjacent radicals Rc and Rd, R'c and R'd borne by the same nitrogen atom together form a heterocyclic or heteroaryl group; preferentially, the heterocycle or heteroaryl is monocyclic and 5- to 7-membered; more preferentially, the groups are chosen from imidazolyl and pyrrolidinyl;

• Re and R'e, which may be identical or different, represent a linear or branched C1- Ce alkylene or C2-C6 alkenylene hydrocarbon-based chain;

• Rf and R'f, which may be identical or different, represent a group di(Ci- C4)alkylamino, (R")(R"')N- or a quaternary ammonium group (R")(R"')(R"")N+- in which R", R'" and R"", which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl group or alternatively (R")(R"')(R"")N+- represents an optionally substituted cationic heteroaryl group, preferentially an imidazolinium group optionally substituted with a C1-C3 alkyl group;

• Rg, R'g, R"g, R"'g, Rh, R'h, R"h, and R'"h, which may be identical or different, represent a hydrogen atom, a halogen atom, an amino, C1-C4 alkylamino, C1-C4 dialkylamino, cyano, carboxyl, hydroxyl or trifluoromethyl group, an acylamino, C1- C4 alkoxy, (poly)hydroxy(C2-C4)alkoxy, alkylcarbonyloxy, alkoxycarbonyl or alkylcarbonylamino radical, an acylamino, carbamoyl or alkylsulfonylamino radical, an aminosulfonyl radical, or a C1-C16 alkyl radical optionally substituted with a group chosen from C1-C12 alkoxy, hydroxyl, cyano, carboxyl, amino, C1-C4 alkylamino and C1-C4 dialkylamino, or alternatively the two alkyl radicals borne by the nitrogen atom of the amino group form a 5- to 7-membered heterocycle optionally comprising another heteroatom identical to or different from that of the nitrogen atom; preferentially, Rg, R'g, R"g, R'"g, Rh, R'h, R"h, and R"'h represent a hydrogen or halogen atom or a C1-C3 alkyl group;

or alternatively two groups Rg and R'g; R"g and R'"g; Rh and R'h; R"h and R"'h borne by two adjacent carbon atoms together form a benzo or indeno ring, a fused heterocycloalkyl or fused heteroaryl group; the benzo, indeno, heterocycloalkyl or heteroaryl ring being optionally substituted with a halogen atom, an amino, C1-C4 alkylamino, C1-C4 dialkylamino, nitro, cyano, carboxyl, hydroxyl or trifluoromethyl group, an acylamino, C1-C4 alkoxy, (poly)hydroxy(C2-C4)alkoxy, alkylcarbonyloxy, alkoxycarbonyl or alkylcarbonylamino radical, an acylamino, carbamoyl or alkylsulfonylamino radical, an aminosulfonyl radical, or a C1-C16 alkyl radical optionally substituted with: a group chosen from C1-C12 alkoxy, hydroxyl, cyano, carboxyl, amino, C1-C4 alkylamino, C1-C4 dialkylamino, or alternatively the two alkyl radicals borne by the nitrogen atom of the amino group form a 5- to 7-membered heterocycle optionally comprising another heteroatom identical to or different from that of the nitrogen atom; preferentially, Rg and R'g; R"g and R"'g together form a benzo group;

or alternatively two groups Ri and Rg; R"'i and R"'g; R'i, and R'h; and/or R"i and R"h together form a fused (hetero)cycloalkyl, preferentially cycloalkyl such as cyclohexyl;

or alternatively when G represents -NRcRd and G' represents –NR'cR'd, two groups Rc and R'g; R'c and R"g; Rd and Rg; R'd and R"'g together form a saturated heteroaryl or heterocycle, optionally substituted with one or more C1-C6 alkyl groups, preferentially a 5- to 7-membered heterocycle containing one or two heteroatoms chosen from nitrogen and oxygen; more preferentially the heterocycle is chosen from morpholinyl, piperazinyl, piperidinyl and pyrrolidinyl groups;

• Ri, R'i, R"i, and R"'i, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl group;

• R1, R2, R3, R4, R'1, R'2, R'3, and R'4, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl, C1-C12 alkoxy, hydroxyl, cyano, carboxy, amino, C1-C4 alkylamino or C1-C4 dialkylamino group, said alkyl radicals possibly forming, with the nitrogen atom which bears them, a 5- to 7-membered heterocycle optionally comprising another nitrogen or non-nitrogen heteroatom; preferentially, R1, R2, R3, R4, R'1, R'2, R'3, and R'4 are hydrogen atoms, or a (C1-C4)alkyl or amino group; more preferentially, R1, R2, R3, R4, R'1, R'2, R'3, and R'4 represent a hydrogen atom;

• Ta and Tb, which may be identical or different, represent i) either a covalent bond s, ii) or one or more radicals or combinations thereof chosen from -SO2-, –O-, -S-, - N(R)-, -N+(R)(R°)- and -CO-, with R and R°, which may be identical or different, representing a hydrogen atom, a C1-C4 alkyl radical or a C1-C4 hydroxyalkyl; or an aryl(C1-C4)alkyl radical; preferentially, Ta is identical to Tb and they represent a covalent bond s or a group chosen from -N(R)-, -C(O)-N(R)-, -N(R)-C(O)-, -O-C(O)- , -C(O)-O- and -N+(R)(R°)-, with R and R°, which may be identical or different, representing a hydrogen atom or a C1-C4 alkyl group; more preferentially, Ta and Tb represent a bond s; iii) or a cationic or non-cationic, preferentially monocyclic heterocycloalkyl or heteroaryl radical, which are preferentially identical, preferentially containing two heteroatoms (more preferentially two nitrogen atoms) and preferentially being 5- to 7-membered, such as imidazolium;

• which may be identical or different, represent an optionally

substituted group; preferentially, the heterocycles are identical, monocyclic and saturated, and comprise in total two nitrogen atoms and from 5 to 8 ring members;

•
represent an aryl or heteroaryl group fused to the imidazolium or phenyl ring; or alternatively is absent from the imidazolium or phenyl ring; preferentially, when the ring is present, the ring is a benzo;

• m, m', n and n', which may be identical or different, represent an integer between 0 and 6 inclusive, with m+n and m'+n', which may be identical or different, represent an integer between 1 and 10 inclusive; preferentially, m+n = m'+n' = an integer between 2 and 4 inclusive; more preferentially, m+n = m'+n' = an integer equal to 2;

• Y represents a hydrogen atom, or a group chosen from:

➢ (C1-C4)alkylcarbonyl, for instance methylcarbonyl or ethylcarbonyl;

➢ arylcarbonyl such as phenylcarbonyl;

➢ (C1-C4)alkoxycarbonyl;

➢ aryloxycarbonyl;

➢ aryl(C1-C4)alkoxycarbonyl;

➢ (di)(C1-C4)(alkyl)aminocarbonyl such as dimethylaminocarbonyl;

➢ (C1-C4)(alkyl)arylaminocarbonyl;

➢ optionally substituted aryl such as phenyl;

➢ 5- or 6-membered monocyclic heteroaryl such as imidazolyl or pyridyl;

➢ cationic 5- or 6-membered monocyclic heteroaryl such as pyrylium, pyridinium, pyrimidinium, pyrazinium, pyridazinium, triazinium, imidazolium; these groups being optionally substituted with one or more identical or different (C1-C4)alkyl groups such as methyl;

➢ cationic 8- to 11-membered bicyclic heteroaryl such as benzimidazolium or benzoxazolium; these groups being optionally substituted with one or more identical or different (C1-C4)alkyl groups such as methyl;

➢ cationic heterocycle having the following formula:

➢ -C(NH2)=N+H2; An'"-; with An'"- being an anionic counterion as defined previously;

➢ -C(NH2)=NH;

➢ SO3-, M+ with M+ representing an alkali metal such as sodium or potassium;

and

• M' representing an anionic counterion, derived from a salt of an organic or mineral acid, or from an organic or mineral base that ensures the electrical neutrality of the molecule;

in particular, the disulfide, thiol or protected-thiol fluorescent dye(s) are chosen from the dyes of formulae (VIIIb), (VIIIb'), (IXb) and (IXb') as defined previously.

14. Process according to any one of the preceding claims, in which b) disulfide, thiol or protected-thiol fluorescent dye(s) are chosen from:

- the dyes of formula (XVIb) or (XVI""b) below:

and also the organic or mineral acid or base salts thereof, the optical and geometric isomers and tautomers thereof, and the solvates thereof such as hydrates;

in which formula (XVIb) or (XVI""b):

• R'1 represents a C1-C4 alkyl group substituted with one or more hydroxyl groups, particularly with only one hydroxyl group, or -C(O)OR' with R' representing a hydrogen atom, a C1-C4 alkyl group or a group -C(O)-O- and, in the latter case, an anionic counterion An- is absent; preferentially, R'1 represents a C1-C4 alkyl group substituted with a hydroxyl group;

• R'2 represents a C1-C4 alkyl group optionally substituted with one or more hydroxyl groups, particularly with only one hydroxyl group;

more particularly, R'1 and R'2 are identical;

• Ra, Rb and Rc represents a (C1-C6)alkyl group such as methyl, they are in particular in positions 3', 4' and 5', or 2', 4' and 5' or 2', 4' and 6', they are preferably in positions 2', 4' and 5',

• An- represents an anionic counterion as defined previously;

• B represent a divalent amido group -C(O)-N(R)- or -N(R)-C(O)-, with R representing a hydrogen atom or a (C1-C6)alkyl group; preferentially, R represents a hydrogen atom;

• n and m, , which may be identical or different, represent an integer between 1 and 4 inclusive, preferentially n is equal to 3 and m is equal to 2;

• Y is as defined previously;

it being understood that the bond between the pyridinium ring and the double bond of the ethylene or styryl group is located in position 2 or 4 of the pyridinium, preferentially at 4; and/or

- the dyes of formula (XIIb) or (XIIb') below:

and also the organic or mineral acid or base salts thereof, the optical and geometric isomers and tautomers thereof, and the solvates thereof such as hydrates,

in which formulae (XIIb) and (XIIb'):

➢ R and R"', which may be identical or different, represent a hydroxyl group, an amino group (NRaRb) or an ammonium group (N+RaRbRc), An-; preferentially hydroxyl; with

Ra, Rb and Rc, which may be identical or different, representing a hydrogen atom or a (C1-C4)alkyl group;

or alternatively two alkyl groups Ra and Rb of the amino or ammonium group form a 5- to 7-membered heterocycle optionally comprising another nitrogen or non- nitrogen heteroatom, such as morpholinyl, piperazinyl, piperidinyl, pyrrolyl, morpholinium, piperazinium, piperidinium or pyrrolinium, and An- representing an anionic counterion;

➢ R' and R", which may be identical or different, represent a hydrogen atom or a group as defined for R and R'" respectively;

➢ Rg, R'g, R"g, R'"g, Rh, R'h, R"h and R'"h, which may be identical or different, represent a hydrogen or halogen atom, an amino, (di)(C1-C4)alkylamino, cyano, carboxyl, hydroxyl, trifluoromethyl, acylamino, C1-C4 alkoxy, C2-C4 (poly)hydroxyalkoxy, (C1-C4)alkylcarbonyloxy, (C1-C4)alkoxycarbonyl, (C1- C4)alkylcarbonylamino, acylamino, carbamoyl or (C1-C4)alkylsulfonylamino group, an aminosulfonyl radical or a (C1-C16)alkyl radical optionally substituted with a group chosen from (C1-C12)alkoxy, hydroxyl, cyano, carboxyl, amino and (di)(C1- C4)alkylamino, or alternatively the two alkyl radicals borne by the nitrogen atom of the amino group form a 5- to 7-membered heterocycle optionally comprising another nitrogen or non-nitrogen heteroatom; in particular, Rg, R'g, R"g, R'"g, Rh, R'h, R"h and R"'h represent a hydrogen atom or a (C1-C4)alkyl group;

➢ R'i, R"i, R'"i and R"'i, which may be identical or different, represent a hydrogen atom or a (C1-C4)alkyl group; in particular R'i, R"i, R"'i and R""i represent a hydrogen atom;

➢ m, and m', which may be identical or different, represent an integer between 1 and 10 inclusive; in particular, an integer between 2 and 4 inclusive; preferentially m and m' are equal to 2;

➢ p, p', q and q', which may be identical or different, represent an integer between 1 and 6 inclusive;

➢ M' representing an anionic counterion; and

➢ Y is as defined previously;

in particular, Rh, R"h are in the ortho position with respect to the pyridinium group and R'h, R"h represent a hydrogen atom; advantageously the dyes of formulae (XIIb) and (XIIb') possess their ethylene group in the para position with respect to the phenyl bearing the amino group: R'(CH2)p-N-(CH2)q-R and/or R"(CH2)p'-N-(CH2)q'-R"', i.e. in position 4', preferentially bear an ethylene or styryl group linking the pyridinium part to the phenyl in the ortho position with respect to the pyridinium, i.e. 2-4'.

15. Process according to any one of the preceding claims, in which the disulfide, thiol or protected-thiol fluorescent dye(s) is (are) chosen from the dyes having the following chemical structures:

with An- and M', which may be identical or different, particularly identical, representing anionic counterions; more particularly, the anionic counterion is chosen from halides such as chloride, alkyl sulfate such as methyl sulfate, mesylate and ½ (O=)2SO2- or ½ SO42-; preferentially 31., 44, 49, 49a, 55, 56 and 56a, more particularly 44, 56 and 56a.

16. Dyeing process according to any one of the preceding claims, in which the total amount of disulfide, thiol or protected-thiol fluorescent dye(s) is between 0.001% and 30% inclusive, relative to the total weight of the composition which contains it (them), preferably the amount of disulfide, thiol or protected-thiol fluorescent dye(s) is between 0.01% and 5% by weight inclusive, relative to the total weight of the composition, more preferentially in a total amount of between 0.01% and 3% inclusive, better still between 0.05% and 2% inclusive, relative to the total weight of the composition which comprises it (them).

17. Process according to any one of the preceding claims, which also comprises the application to said keratin fibres of one or more reducing agents c), said reducing agent(s) c) possibly being applied before, at the same time as or after the application of the direct dye(s) a) as defined in any one of Claims 1 to 8, and/or the disulfide, thiol or protected-thiol fluorescent dye(s) as defined in any one of Claims 1 and 9 to 16; or alternatively said reducing agent(s) c) is (are) present with the direct dye(s) a) as defined in any one of Claims 1 to 8, and/or the disulfide, thiol or protected-thiol fluorescent dye(s) as defined in any one of Claims 1 and 9 to 16; preferably, said reducing agent(s) are chosen from i) the reducing agents of formula (lc) below, and also the addition salts thereof and mixtures thereof:

H(X)q(R10)t (Ic)

in which formula (Ic),

- X represents P, S or SO2,

- q represents an integer equal to 0 or 1,

- t represents an integer equal to 1 or 2, and

- R10 represents a linear or branched, saturated or unsaturated C1 to C20 alkyl radical, optionally interrupted with a heteroatom, and/or optionally substituted with one or more radicals chosen from hydroxyl, halo, amine, carboxyl, ((C1-C30)alkoxy)carbonyl, amido, ((C1-C30)alkyl)aminocarbonyl, ((C1-C30)acyl)amino, mono- or dialkylamino, and mono- or dihydroxylamino radicals;

ii) thioglycolic acid, iii) thiolactic acid, iv) glyceryl monothioglycolate, v) cysteamine, vi) N-acetylcysteamine, vii) N-propionylcysteamine, viii) cysteine, ix) N-acetylcysteine, x) thiomalic acid, xi) pantotheine, xii) 2,3-dimercaptosuccinic acid, xiii) N-(mercaptoalkyl)-ω-hydroxyalkylamides, xiv) N-mono or N,N-dialkylmercapto-4-butyramides, xv) aminomercaptoalkylamides, xvi) N-(mercaptoalkyl)succinamic acid derivatives, xvii) N-(mercaptoalkyl)succinimide acid derivatives, xviii) alkylaminomercaptoalkylamides, ix) an azeotropic mixture of 2-hydroxypropyl thioglyconate and of (2-hydroxy-1-methyl)ethyl thioglycolate, x) mercaptoalkylaminoamides, xi) N-mercaptoalkylalcanediamides, xii) formamidine sulfinic acid derivatives, the addition salts thereof and mixtures thereof; preferably, the reducing agent(s) c) is (are) in the presence of the direct dye(s) a) as defined in any one of Claims 1 to 8, and of the disulfide, thiol or protected-thiol fluorescent dye(s) as defined in any one of Claims 1 and 9 to 16, or alternatively the reducing agent(s) c) are applied at the same time as the dye(s) a) as defined in any one of Claims 1 to 8, and the disulfide, thiol or protected-thiol fluorescent dye(s) as defined in any one of Claims 1 and 9 to 16.

18. Process according to any one of Claims 1 to 16, which does not use any reducing agent.

19. Process according to any one of the preceding claims, in which the direct dye(s) a),

as defined in any one of Claims 1 to 8, and the disulfide, thiol or protected-thiol fluorescent dye(s) b), as defined in any one of Claims 1 and 9 to 16, are applied jointly to the keratin fibres; preferably, the process comprises a step of applying to the keratin fibres a cosmetic composition which comprises one or more direct dye(s) a), as defined in any one of Claims 1 to 8, and one or more disulfide, thiol or protected-thiol fluorescent dye(s) b) as defined in any one of Claims 1 and 9 to 16.

20. Process according to any one of Claims 1 to 18, which comprises at least the two successive steps below:

- a first step of applying to said keratin fibres a cosmetic composition comprising one or more disulfide, thiol or protected-thiol fluorescent dyes b), as defined in any one of Claims 1 and 9 to 16, followed by

- a second step of applying to said fibres a cosmetic composition comprising one or more direct dyes a), as defined in any one of Claims 1 to 8; or alternatively

- a first step of applying to said keratin fibres a cosmetic composition comprising one or more direct dyes a), as defined in any one of Claims 1 to 8, followed by

- a second step of applying to said fibres a cosmetic composition comprising one or more disulfide, thiol or protected-thiol fluorescent dyes b), as defined in any one of Claims 1 and 9 to 16.

21. Process according to any one of the preceding claims, which also comprises the application to said keratin fibres of one or more oxidizing agents applied after application of one or more direct dyes a), as defined in any one of Claims 1 to 8, and one or more disulfide, thiol or protected-thiol fluorescent dyes b) as defined in any one of Claims 1 and 9 to 16.

22. Process according to any one of the preceding claims, in which the pH of the cosmetic composition(s) is between 2 and 12, preferably between 2 and 11 inclusive, preferably between 2.5 and 10.5, more preferentially between 3 and 10.

23. Process according to any one of Claims 17 and 19 to 22, in which the composition which comprises the reducing agent(s) c) also comprises at least two alkaline agents different from one another; in particular, one of the alkaline agents is a bicarbonate, more particularly an ammonium bicarbonate; preferentially, the bicarbonate is in the reducing composition comprising in particular thioglycolic acid (TGA) as reducing agent.

24. Cosmetic composition comprising one or more direct dyes a), as defined in any one

of Claims 1 to 8, and one or more disulfide, thiol or protected-thiol fluorescent dyes b), as defined in any one of Claims 1 and 9 to 16, said composition optionally also comprising one or more reducing agents c) as defined in Claim 17, and optionally having a pH of between 2 and 12 inclusive, preferably of between 2 and 11 inclusive, preferably between 2.5 and 10.5, more preferentially between 3 and 10.

25. Multi-compartment device comprising:

- either a first compartment containing one or more direct dyes a), as defined in any one of Claims 1 to 8, and a second compartment containing one or more disulfide, thiol or protected-thiol fluorescent dyes b), as defined in any one of Claims 1 and 9 to 16; optionally a third compartment containing one or more reducing agents c), as defined in Claim 17, and optionally another compartment containing one or more oxidizing agents d);

- or a first compartment containing one or more direct dyes a), as defined in any one of Claims 1 to 8, and one or more disulfide, thiol or protected-thiol fluorescent dyes b), as defined in any one of Claims 1 and 9 to 16; optionally a second compartment containing one or more reducing agents c), as defined in Claim 17, and optionally another, third, compartment containing one or more oxidizing agents d).

26. Use of one or more disulfide, thiol or protected-thiol fluorescent dye(s) b), as defined in any one of Claims 1 and 9 to 16, combined with one or more direct dye(s) a), as defined in any one of Claims 1 to 8, for dyeing keratin materials, in particular human keratin fibres such as the hair, in a chromatic colour, without using an additional dye different from the dyes a) or b).