HAIR DYEING PROCESS USING HENNA AND THEN INDIGO AND AN OIL AND/OR

BUTTER

The invention relates to a process for dyeing keratin fibres, especially human keratin fibres such as the hair, in several successive steps, using in a first stage i) a composition B comprising at least 10% by weight of henna powder, followed by ii) rinsing until composition B has been removed, and then iii) a composition B' comprising at least 10% by weight of powder of indigo-producing plant(s), it being understood that at least one of the two compositions B or B' also comprises at least one oil and/or at least one butter preferably of plant origin.

Two major methods for dyeing human keratin fibers, and in particular the hair, are known.

The first, known as oxidation dyeing or permanent dyeing, consists in using one or more oxidation dye precursors, more particularly one or more oxidation bases optionally combined with one or more couplers.

Oxidation bases are usually selected from ortho- or para-phenylenediamines, ortho- or para-aminophenols, and heterocyclic compounds. These oxidation bases are colourless or weakly coloured compounds, which, when combined with oxidizing products, can give rise via a process of oxidative condensation to coloured species, which remain trapped within the fibre.

The shades obtained with these oxidation bases are often varied by combining them with one or more couplers, these couplers being chosen especially from aromatic meta- diamines, meta-aminophenols, meta-diphenols and certain heterocyclic compounds, such as indole compounds.

The variety of molecules used as oxidation bases and couplers allows a wide range of colours to be obtained.

The second dyeing method, known as direct dyeing or semi-permanent dyeing, comprises the application of direct dyes, which are coloured and colouring molecules that have affinity for fibres. Given the nature of the molecules used, they tend rather to remain on the surface of the fibre and penetrate relatively little into the fibre, when compared with the small molecules of oxidation dye precursors. The main advantages of this type of dyeing are that it does not require any oxidizing agent, which limits the degradation of the fibres, and that it does not use any dyes that have particular reactivity, resulting in limitation of the intolerance risks.

The first hair dyes were semi-permanent. One of the most well known natural dyes is that derived from the henna plant. Henna continues to be used in feminine beauty enhancement for colouring the hair or the nails, or for dyeing leather, silk and wool, etc. It is also be used traditionally for various important events, celebrations and beliefs.

Red henna consists of leaves of shrubs of the genus Lawsonia from the family of Lythraceae, which is based on the principle of dyeing with the active agent lawsone: 2- hydroxy-1 ,4-naphthoquinone. Lawsone [83-72-7] (CI Natural Orange 6 ; CI 75420), also known as isojuglone, may be found in henna shrubs (Lawsonia alba, Lawsonia inermis) ("Dyes, Natural", Kirk-Othmer Encyclopedia of Chemical Technology, "Henna" Encyclopedia Britannica).

This dye affords an orange-red coloration on grey hair, and a "warm" i.e. coppery to red colour on chestnut-brown hair. The dyeing process using henna is difficult to perform. A kind of "paste" (often referred to as a "poultice") is first made from ground or powdered henna leaves, which is then diluted at the time of use with warm water, and the said paste is then applied to the keratin fibres.

However, this process using the said paste has drawbacks. During the preparation and application of the composition to keratin fibres, it is not always possible to obtain satisfactory impregnation due to the poor consistency of the composition obtained from the coarsely ground powder. Furthermore, it is very difficult to hope to reproduce shades exactly, since the lawsone content very often varies from one batch to another and between different ground materials.

Another very well-known natural dye is indigo (see Ullmann's Encyclopedia of Industrial Chemistry, "Hair preparation", point 5.2.3, 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim; 10.1002/14356007.a12 571.pub2). Indigo continues to be used in feminine beauty enhancement for dyeing the hair or the nails, or for dyeing fabrics (jeans), leather, silk, wool, etc. Indigo [482-89-3] is a natural dye, originating especially from the indigo plant, and having the empirical formula the structure:

Indigo is derived from indican and may be prepared from various plants known as indigo-producing plants such as Indigofera tinctoria, Indigo suffruticosa, Isatis tinctoria, etc. (see Kirk-Othmer Encyclopedia of Chemical Technology, updated on 17/04/2009, DOI: 10.1002/0471238961 .0425051903150618.a01.pub2). The indigo-producing plants are generally chopped and soaked in hot water, heated, fermented and oxidized in the open air to liberate the purple-blue coloured indigo (see Chem. Rev. 201 1 , 111 , 2537-2561 , pp. 2537-2561 ). Indigo is the result of the fermentation and then oxidization of indican (glycosyl precursor). The indigo molecule is insoluble in water.

The problem is that dyeing using the indigo plant is difficult because the uptake of the colour into the keratin fibres is very poor. This dye affords a blue coloration on grey hair, and a "cold" colour of ash to violet colour on chestnut-brown hair. The dyeing process using indigo leaves is difficult to perform. A kind of "paste" (often referred to as a poultice) is first made from ground or powdered leaves of indigo plant (or Indian indigo or dyer's indigo) or dyer's pastel (or wood or Isatis tinctoria), which needs to have been fermented, and which is then diluted at the time of use with warm water, and the said paste is then applied to the keratin fibres. However, this process using the said paste has drawbacks. During the preparation and application of the composition to keratin fibres, it is not always possible to obtain satisfactory impregnation due to the poor consistency of the composition obtained from the coarsely ground powder. Furthermore, it is very difficult to hope to reproduce shades exactly, since the indigo content very often varies from one batch to another and between different ground materials.

As much as the colour obtained on chestnut-brown hair has a natural look, grey hair is dyed an unaesthetic and unnatural orange colour with henna or blue colour with indigo ("Hair preparations", Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, Inc.). Furthermore, the colorations obtained are not homogenous between the root and the end or from one fibre to another (The Science of Hair Care, C. Bouillon, J. Wilkinson, 2d Ed., CRC Press, Taylor & Francis Group; Boca Raton, London, pp. 236-241 (2005)).

Added to this are the risks of staining of clothing and the skin with henna or indigo during the preparation of the "paste" and also during its application to the keratin fibres, since the consistency is very irregular.

The current colorations with henna products and products derived from indigo- producing plant(s) are applied in the form of a poultice for a long leave-on time on the hair and are then rinsed out, and the hair is dried, generally in the open air without final shampooing, so as to allow the coloration to become oxidized in the air in the course of the following hours or even days. Depending on the composition used, the oxidation time is more or less long, but is never instantaneous.

Besides the leave-on time, which is long with henna or indigo and which may range from a few tens of minutes to a few hours (overnight) depending on the desired intensity, without being able to control the result, the result also varies as a function of the fibres to be dyed and of the indigo or henna raw material used.

It is known practice to use metal salts as mordants for improving coloration with henna and indigo {Ullmann's Encyclopedia, 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a12 571 .pub2 and US 2010/03133362). It is also known practice to use metal salts to improve for dyeing of indigo (vat dyes - see Chem. Rev. 201 1 , 111 , 2537- 2561 , pp. 2537-2561 ). The use of these agents requires great know-how, multiplies the steps of the process, is not always friendly towards the integrity of the fibre (cosmetically unfriendly) and may disrupt subsequent cosmetic treatments.

It is also known practice to use a heating iron combined with a non-natural direct dye for dyeing the hair (EP 1 631 241 ). However, the colorations are not always satisfactory from the point of view of the colour, especially in terms of selectivity from the root to the end and of persistence, and of the cosmetic aspect of the fibres.

To overcome the problem of the poor dyeing efficacy of natural dyes, it is moreover known practice to "dope" the coloration by adding direct dyes that are generally used in direct dyeing, such as nitrobenzene, anthraquinone, nitropyridine, azo, methine, azomethine, xanthene, acridine, azine or triarylmethane direct dyes (DE 199 05 707, EP 0 806 199, JP 2010-0001278). This option has the drawback for natural product users, or for partisans of "natural/bio" products, in that the coloration is partly performed using synthetic dyes.

Another solution is to couple two colorations in order to obtain brown colours from a natural dye. For example, it is known practice to perform a coloration in two steps, the first step of which is to dye the hair with henna, and then, in a second step, to dye the hair with indigo. However, in general, the colours obtained are unpredictable, and may be very unaesthetic with one colour dominating over the other, either being too orangey because of the henna, or too blue-violet because of the indigo. The colours obtained are not always reproducible by users. Furthermore, the leave-on times are problematic and the cosmetic aspect of the fibre is not always respected. Finally, the coloration obtained is not always homogeneous from one fibre to another or from the root to the end, with a very pronounced root effect.

There is thus a real need to develop dyeing processes using natural dyes, which make it possible to obtain powerful colorations from henna and from indigo-producing plant(s), which have a natural colour without tending towards blue or orange, even on very light or even white keratin fibres, while at the same time respecting the cosmetic aspect of the keratin fibres. In particular, there is a need to provide keratin fibre dyeing processes using natural dyes, that are quick and easy to use and can especially produce colorations that are less aggressive to the hair and at the same time that are resistant to external agents (light, bad weather or shampooing), and that are fast and homogeneous, while at the same time remaining powerful and chromatic.

This (these) aim(s) are achieved by the present invention, one subject of which is a process for dyeing keratin fibres, in particular human keratin fibres such as the hair, involving the following steps:

- i) in a first stage, treating the keratin fibres with an aqueous composition B comprising: a) at least 10% by weight, relative to the weight of the said composition, of red henna powder; and

b) optionally at least one oil, preferably of plant origin, and/or at least one butter, preferably of plant origin; and then

- ii) in a second stage, removing the composition from the keratin fibres, preferably by rinsing;

- iii) optionally applying a heat treatment to the keratin fibres, at a temperature above 60°C, preferably ranging from 60°C to 220°C, preferably with a hairdryer or a heating iron; - iv) and then treating the keratin fibres with an aqueous composition B' comprising:

a') at least 10% by weight, relative to the weight of the said composition, of powder of indigo-producing plant(s) and

b') optionally at least one oil, preferably of plant origin, and/or at least one butter, preferably of plant origin;

followed by repeating steps ii) and iii);

it being understood that at least one of the two compositions B or B' comprises at least one oil and/or one butter b) or b'). The compositions B and B' used are particularly derived from the mixing of a composition A or A', respectively, which is compact and/or anhydrous, respectively, with an aqueous composition C and C and more preferentially water.

The keratin fibre dyeing process according to the invention has the advantage of dyeing keratin fibres, especially human keratin fibres, with strong, chromatic colorations that are resistant to washing, perspiration, sebum and light, and that are moreover long-lasting, without impairing the said fibres. Furthermore, the colorations obtained using the composition or the poultice give homogenous colours from the root to the end of a fibre (little coloration selectivity).

The treated keratin fibres have a very pleasant cosmetic aspect, and their integrity is respected.

Moreover, the time dedicated to dyeing using a natural product according to a variant of the process of the invention is faster and easier than the known two-step processes, simply by subjecting the keratin fibres treated with henna and then with indigo-producing plant(s), combined in the presence of an oil or butter and with a source of heat such as a heating iron, without the need to keep one or more compositions such as poultices on the head for a long time (for several hours or even overnight) or to leave the poultice composition(s) to stand, for example, before application for a long time (several hours or even several days) between each step of application of the red henna and of the indigo.

This variant of the dyeing process according to the invention thus makes it possible to obtain aesthetic colorations rapidly without having to wait a long time for the oxidation of the dye precursors in the open air.

a) Red henna powder and a') powder of indigo-producing plant(s)

Composition B used in the keratin fibre dyeing process comprises at least 10% by weight of henna in powder form, preferably as fine particles, relative to the total weight of the said composition. The henna used in the invention is red henna (Lawsonia inermis, alba).

The henna powder may be screened to obtain particles with upper limit sizes corresponding to the orifices or mesh sizes of the screen particularly between 35 and 80 mesh (US).

According to one particular mode of the invention, the size of the henna powder particles is fine. According to the invention, a particle size of less than or equal to 500 μηη is more particularly intended. Preferentially, the powder consists of fine particles with sizes inclusively between 50 and 300 μηη and more particularly between 10 and 200 μηη.

It is understood that the said henna particles preferentially have a moisture content of between 0 and 10% by weight relative to the total weight of the powders.

Preferably, the said henna particles are derived from henna leaves.

Composition B according to the invention comprises henna powder in an amount particularly inclusively between 10% and 90% by weight, more particularly between 15% and 70%, or even between 20% and 60% by weight and more particularly between 25% and 50% by weight, relative to the total weight of the said composition.

Composition A, which is preferably anhydrous and compact, comprises henna powder in an amount particularly inclusively between 15% and 100% by weight, more particularly between 20% and 80%, or even between 25% and 70% by weight and more particularly between 25% and 60% by weight, relative to the total weight of the said composition.

Composition B' used in the keratin fibre dyeing process comprises at least 10% by weight of powder of indigo-producing plant(s), preferably as fine particles, relative to the total weight of the composition.

As indigo-producing plants, mention may be made of numerous species derived from the following genera:

- Indigofera such as Indigofera tinctoria, Indigo suffraticosa, Indigofera articulata,

Indigofera arrecta, Indigofera gerardiana, Indigofera argenta, Indigofera indica,

Indigofera longiracemosa;

- Isatis such as Isatis tinctoria;

- Polygonum or Persicaria such as Polygonum tinctorium (Persicaria tinctoria);

- Wrightia such as Wrightia tinctoria;

- Calanthe such as Calanthe veratrifolia; and

- Baphicacanthus such as Baphicacanthus cusia.

Preferably, the indigo-producing plant is of the genus Indigofera and more particularly is Indigofera tinctoria.

Use may be made of all or part (in particular the leaves especially for Indigofera tinctoria) of the indigo-producing plant.

The indigo-producing plant powder may be screened to obtain particles with upper limit sizes corresponding to the orifices or mesh sizes of the screen particularly between 35 and 80 mesh (US).

According to a particular mode of the invention, the size of the indigo-producing plant powder particles is fine. According to the invention, a particle size of less than or equal to 500 μπΊ is more particularly intended. Preferentially, the powder consists of fine particles with sizes inclusively between 50 and 300 μηη and more particularly between 10 and 200 μηη.

It is understood that the said indigo-producing plant particles preferentially have a moisture content of between 0 and 10% by weight relative to the total weight of the powders.

Composition B' according to the invention comprises indigo-producing plant powder in an amount particularly inclusively between 10% and 90% by weight, more particularly between 15% and 70%, or even between 20% and 60% by weight and more particularly between 25% and 50% by weight, relative to the total weight of the said composition.

Composition A', which is preferably anhydrous and compact, comprises indigo- producing plant powder in an amount particularly inclusively between 15% and 100% by weight, more particularly between 20% and 80%, or even between 25% and 70% by weight and more particularly between 25% and 60% by weight, relative to the total weight of the said composition. b) Optionally oils and/or butters

According to a particular embodiment of the invention, at least one of the compositions used in the process of the invention B or B' comprises one or more identical or different oils.

The term "o/T means a "fatty substance" that is liquid at room temperature (25°C) and at atmospheric pressure (760 mmHg); the viscosity at 25°C is preferably less than 1200 cps and better still less than 500 cps (defined, for example, from the Newtonian plateau determined using an ARG2 rheometer from TA Instruments equipped with a spindle with cone-plate geometry 60 mm in diameter and with an angle of 2 degrees over a shear stress range of from 0.1 Pa to 100 Pa).

The term "fatty substance" means an organic compound that is insoluble in water at ordinary temperature (25°C) and at atmospheric pressure (760 mmHg) (solubility of less than 5%, preferably less than 1 % and even more preferentially less than 0.1 %). They have in their structure at least one hydrocarbon-based chain comprising at least 6 carbon atoms or a sequence of at least two siloxane groups. In addition, the fatty substances are generally soluble in organic solvents under the same temperature and pressure conditions, for instance chloroform, dichloromethane, carbon tetrachloride, ethanol, benzene, toluene, tetrahydrofuran (THF), liquid petroleum jelly or decamethylcyclopentasiloxane.

The term "non-silicone o/T means an oil not containing any silicon atoms (Si) and the term "silicone o/T means an oil containing at least one silicon atom.

More particularly, the oils are chosen from non-silicone oils and in particular C ₆ -Ci ₆ hydrocarbons or hydrocarbons containing more than 16 carbon atoms and in particular alkanes; oils of animal origin; triglyceride oils of plant origin; essential oils; fluoro oils or glycerides of synthetic origin, fatty alcohols; fatty acid and/or fatty alcohol esters other than triglycerides, fatty acid amides and silicone oils.

Preferably, the oils are not oxyalkylenated or glycerolated ethers.

Preferably, the oils do not comprise any C ₂ -C ₃ oxyalkylene units or any glycerolated units.

Preferably, the oils are not fatty acids which, in salified form, give water-soluble soaps.

The oils that may be used as second ingredient b) and b') in the composition B and B' in accordance with the invention may be silicones.

The silicones may be volatile or non-volatile, cyclic, linear or branched silicones, which are unmodified or modified with organic groups, having a viscosity from 5x10 ^"6 to 2.5 m ² /s at 25°C, and preferably 1 x10 ^"5 to 1 m ² /s.

Preferably, the silicone is chosen from polydialkylsiloxanes, especially polydimethylsiloxanes (PDMSs), and organomodified polysiloxanes comprising at least one functional group chosen from poly(oxyalkylene) groups, amino groups and alkoxy groups.

Organopolysiloxanes are defined in greater detail in Walter Noll's "Chemistry and Technology of Silicones" (1968), Academic Press. They may be volatile or non-volatile.

When they are volatile, the silicones are more particularly chosen from those with a boiling point of between 60°C and 260°C, and even more particularly from:

(i) cyclic polydialkylsiloxanes comprising from 3 to 7 and preferably 4 to 5 silicon atoms. These are, for example, octamethylcyclotetrasiloxane sold in particular under the name Volatile Silicone ^® 7207 by Union Carbide or Silbione ^® 70045 V2 by Rhodia, decamethylcyclopentasiloxane sold under the name Volatile Silicone ^® 7158 by Union Carbide, and Silbione ^® 70045 V5 by Rhodia, and mixtures thereof.

Mention may also be made of cyclocopolymers of the dimethylsiloxane/methylalkylsiloxane type, such as Volatile Silicone® FZ 3109 sold by the company Union Carbide, of formula:

with D" : Si - O with D' Si - O

C _g H ₁₇

Mention may also be made of mixtures of cyclic polydialkylsiloxanes with organosilicon compounds, such as the mixture of octamethylcyclotetrasiloxane and tetratrimethylsilylpentaerythritol (50/50) and the mixture of octamethylcyclotetrasiloxane and oxy-1 ,1 '-(hexa-2,2,2',2',3,3'-trimethylsilyloxy)neopentane;

(ii) linear volatile polydialkylsiloxanes containing 2 to 9 silicon atoms and having a viscosity of less than or equal to 5x10 ^"6 m ² /s at 25°C. An example is decamethyltetrasiloxane sold in particular under the name SH 200 by the company Toray Silicone. Silicones belonging to this category are also described in the article published in Cosmetics and Toiletries, Vol. 91 , Jan. 76, pp. 27-32, Todd & Byers, Volatile Silicone Fluids for Cosmetics. Use is preferably made of non-volatile polydialkylsiloxanes, polydialkylsiloxane gums and resins, polyorganosiloxanes modified with the organofunctional groups above, and mixtures thereof.

These silicones are more particularly chosen from polydialkylsiloxanes, among which mention may be made mainly of polydimethylsiloxanes having trimethylsilyl end groups. The viscosity of the silicones is measured at 25°C according to ASTM Standard 445 Appendix C.

Among these polydialkylsiloxanes, mention may be made, in a nonlimiting manner, of the following commercial products:

- the Silbione ^® oils of the 47 and 70 047 series or the Mirasil ^® oils sold by Rhodia, for instance the oil 70 047 V 500 000;

- the oils of the Mirasil ^® series sold by the company Rhodia;

- the oils of the 200 series from the company Dow Corning, such as DC200 with a viscosity of 60 000 mm ² /s;

- the Viscasil ^® oils from General Electric and certain oils of the SF series (SF 96, SF 18) from General Electric.

Mention may also be made of polydimethylsiloxanes possessing dimethylsilanol end groups known under the name of dimethiconol (CTFA), such as oils of the 48 series from Rhodia.

The fatty alcohols, fatty acid amides, and fatty acid esters that may be used as second ingredient b) or b') in the compositions B or B' in accordance with the invention are in the form of oils.

It is recalled that, for the purposes of the invention, fatty alcohols, esters and acids more particularly have at least one linear or branched, saturated or unsaturated hydrocarbon-based group comprising 6 to 30 carbon atoms, which is optionally substituted, in particular with one or more hydroxyl groups (in particular 1 to 4). If they are unsaturated, these compounds may comprise one to three conjugated or non-conjugated carbon-carbon double bonds.

More precisely, the ingredient ii) may represent an ester of a C-I-C-IO alcohol and of a

C ₆ -C ₃ o fatty acid such as R-C(0)-0-R' with R representing a linear or branched C ₆ -C ₃ o alkyl or linear or branched C ₆ -C ₃₀ alkenyl group, comprising one or two unsaturations, and R representing a linear or branched C1-C1 ₀ alkyl group.

Preferentially, R represents a linear C1 ₀ -C2 ₀ alkyl group and R' represents a Ci-C ₆ alkyl group that is preferably branched, such as isopropyl myristate.

According to another advantageous variant, the ingredient ii) represents one or more amides of a C ₆ -C ₃ o fatty acid and of a primary or secondary, preferably primary, C1-C1 ₀ amine, such as those of formula R"-C(0)-N(R _a )-R"' with R" representing a linear or branched C ₆ -C ₃₀ alkyl or linear or branched C ₆ -C ₃₀ alkenyl group, comprising one or two unsaturations, which may be substituted with one or more hydroxyl groups, or (di)(Ci-C ₆ )(alkyl)amino, and R'" representing a linear or branched C1-C1 ₀ alkyl group, R _a representing a hydrogen atom or an alkyl group as defined for R'". Preferably, R" represents a C14-C2 ₀ alkenyl group, R _a represents a hydrogen atom and R'" represents a Ci-C ₆ alkyl group optionally substituted with (di)(Ci-C ₄ )(alkyl)amino such as oleylamidopropyldimethylamine. As regards the C ₆ -Ci ₆ alkanes, they are linear or branched, and possibly cyclic.

Examples that may be mentioned include hexane, dodecane and isoparaffins such as isohexadecane and isodecane. The linear or branched hydrocarbons containing more than 16 carbon atoms may be chosen from liquid paraffins, petroleum jelly, liquid petroleum jelly, polydecenes, and hydrogenated polyisobutene such as Parleam ^® .

Among the animal oils, mention may be made of perhydrosqualene.

Among the triglycerides of plant or synthetic origin, mention may be made of liquid fatty acid triglycerides containing from 6 to 30 carbon atoms, for instance heptanoic or octanoic acid triglycerides, or alternatively, for example, sunflower oil, corn oil, soybean oil, marrow oil, grapeseed oil, sesame seed oil, hazelnut oil, apricot oil, macadamia oil, arara oil, castor oil, avocado oil, caprylic/capric acid triglycerides, for instance those sold by the company Stearineries Dubois or those sold under the names Miglyol ^® 810, 812 and 818 by the company Dynamit Nobel, jojoba oil and shea butter oil.

Among the fluoro oils, mention may be made of perfluoromethylcyclopentane and perfluoro-1 ,3-dimethylcyclohexane, sold under the names Flutec ^® PC1 and Flutec ^® PC3 by the company BNFL Fluorochemicals; perfluoro-1 ,2-dimethylcyclobutane; perfluoroalkanes such as dodecafluoropentane and tetradecafluorohexane, sold under the names PF 5050 ^® and PF 5060 ^® by the company 3M, or bromoperfluorooctyl sold under the name Foralkyl ^® by the company Atochem; nonafluoromethoxybutane and nonafluoroethoxyisobutane; perfluoromorpholine derivatives such as 4-(trifluoromethyl)perfluoromorpholine sold under the name PF 5052 ^® by the company 3M.

Among the essential oils contained in the composition of the invention, mention may be made of those mentioned in Ullmann's Encyclopedia of Industrial Chemistry ("Flavors and Fragrances", Karl-Georg Fahlbusch et al., Published Online: 15 JAN 2003, DOI: 10.1002/14356007.a1 1_141 ).

According to a preferred embodiment, the ingredients b) and b') are other than essential oils.

Preferably, the oil(s) of the invention are non-silicone oils. The term "non-silicone o/V means an oil not containing any silicon atoms (Si) and the term "silicone o/V means an oil containing at least one silicon atom. According to a preferred variant of the invention, the oil(s) are chosen from C ₆ -Ci ₆ alkanes, polydecenes, liquid esters of a fatty acid and/or of a fatty alcohol, and liquid fatty alcohols, or mixtures thereof.

Better still, the oils are chosen from liquid petroleum jelly, C ₆ -Ci ₆ alkanes and polydecenes.

In this preferred variant, the oil(s) are chosen from mineral oils such as liquid petroleum jelly.

According to another most particularly preferred mode of the invention, the oils are chosen from oils of natural origin, more particularly oils of plant origin, preferentially chosen from jojoba oil, babassu oil, sunflower oil, olive oil, coconut oil, Brazil nut oil, marula oil, corn oil, argan oil, soybean oil, marrow oil, grapeseed oil, flax oil, sesame oil, hazelnut oil, apricot oil, macadamia oil, arara oil, coriander oil, almond oil, castor oil, avocado oil, shea butter oil, rapeseed oil, borage oil, evening primrose oil, pomegranate oil, mango oil, palm oil, cotton seed oil and copra oil. More particularly, the oils of plant origin are chosen from avocado oil, olive oil, coconut oil, copra oil, argan oil and sunflower oil; preferentially, the oil(s), ingredient b) of the invention, are chosen from copra oils.

Composition B and/or B' used in the process of the invention preferably comprises one or more oils in an amount particularly inclusively between 1 % and 80% by weight, more particularly between 2% and 50% by weight, preferentially between 3% and 40% by weight and more preferentially between 5% and 25% by weight, relative to the total weight of the said composition.

Composition A and/or A' preferably comprises one or more oils in an amount particularly inclusively between 1 % and 80% by weight, relative to the total weight of the composition, more particularly between 5% and 60% by weight, preferentially between 10% and 40% by weight and more preferentially between 15% and 30% by weight, relative to the total weight of the said composition. According to another particular embodiment of the invention, composition B and/or B' used in the process of the invention comprises one or more identical or different butters.

For the purposes of the present invention, the term "butter" (also known as a "pasty fatty substance") means a lipophilic fatty compound with a reversible solid/liquid change of state, comprising at a temperature of 25°C and at atmospheric pressure (760 mmHg), a liquid fraction and a solid fraction.

In other words, the starting melting point of the pasty compound can be less than 25°C. The liquid fraction of the pasty compound measured at 25°C can represent 9% to 97% by weight of the compound. This liquid fraction at 25°C preferably represents between 15% and 85% and more preferably between 40% and 85% by weight.

Preferably, the butter(s) have an end melting point of less than 60°C. Preferably, the butter(s) have a hardness of less than or equal to 6 MPa.

Preferably, the butters or pasty fatty substances have, in the solid state, an anisotropic crystal organization, which is visible by X-ray observation.

For the purposes of the invention, the melting point corresponds to the temperature of the most endothermic peak observed on thermal analysis (DSC) as described in standard ISO 1 1357-3; 1999. The melting point of a pasty substance or of a wax may be measured using a differential scanning calorimeter (DSC), for example the calorimeter sold under the name DSC Q2000 by the company TA Instruments.

As regards the measurement of the melting point and the determination of the end melting point, the sample preparation and measurement protocols are as follows:

A sample of 5 mg of pasty fatty substance, preheated to 80°C and withdrawn with magnetic stirring using a spatula that is also heated, is placed in a hermetic aluminium capsule, or a crucible. Two tests are performed to ensure the reproducibility of the results.

The measurements are performed on the abovementioned calorimeter. The oven is flushed with nitrogen. Cooling is performed by an RCS 90 heat exchanger. The sample is then subjected to the following protocol: it is first placed at a temperature of 20°C, and then subjected to a first temperature rise passing from 20°C to 80°C, at a heating rate of 5°C/minute, then is cooled from 80°C to -80°C at a cooling rate of 5°C/minute and finally subjected to a second temperature rise passing from -80°C to 80°C at a heating rate of 5°C/minute. During the second temperature rise, the variation of the difference in power absorbed by the empty crucible and by the crucible containing the sample of butter is measured as a function of the temperature. The melting point of the compound is the temperature value corresponding to the top of the peak of the curve representing the variation in the difference in power absorbed as a function of the temperature.

The end melting point corresponds to the temperature at which 95% of the sample has melted.

The liquid fraction by weight of the butter at 25°C is equal to the ratio of the heat of fusion consumed at 25°C to the heat of fusion of the butter.

The heat of fusion of the pasty compound is the heat consumed by the compound in order to pass from the solid state to the liquid state. The butter is said to be in the solid state when all of its mass is in crystalline solid form. The butter is said to be in the liquid state when all of its mass is in liquid form.

The heat of fusion of the butter is equal to the integral of the entire melting curve obtained using the abovementioned calorimeter, with a temperature rise of 5 or 10°C/minute, according to standard ISO 1 1357-3:1999. The heat of fusion of the butter is the amount of energy required to make the compound change from the solid state to the liquid state. It is expressed in J/g. The heat of fusion consumed at 25°C is the amount of energy absorbed by the sample to change from the solid state to the state that it has at 25°C, composed of a liquid fraction and a solid fraction.

The liquid fraction of the butter measured at 32°C preferably represents from 30% to 100% by weight of the compound, preferably from 50% to 100%, more preferably from 60% to 100% by weight of the compound. When the liquid fraction of the butter measured at 32°C is equal to 100%, the temperature of the end of the melting range of the pasty compound is less than or equal to 32°C.

The liquid fraction of the butter measured at 32°C is equal to the ratio of the heat of fusion consumed at 32°C to the heat of fusion of the pasty compound. The heat of fusion consumed at 32°C is calculated in the same way as the heat of fusion consumed at 23°C.

As regards the measurement of the hardness, the sample preparation and measurement protocols are as follows:

The composition according to the invention or the butter is placed in a mould 75 mm in diameter, which is filled to about 75% of its height. In order to overcome the thermal history and to control the crystallization, the mould is placed in a Votsch VC 0018 programmable oven, where it is first placed at a temperature of 80°C for 60 minutes, then cooled from 80°C to 0°C at a cooling rate of 5°C/minute, and then left at the stabilized temperature of 0°C for 60 minutes, and then subjected to a temperature rise ranging from 0°C to 20°C, at a heating rate of 5°C/minute, and then left at the stabilized temperature of 20°C for 180 minutes.

The compression force measurement is taken using a TA TX2i texturometer from Swantech. The spindle used is chosen according to the texture:

- cylindrical steel spindle 2 mm in diameter for very rigid starting materials;

- cylindrical steel spindle 12 mm in diameter for sparingly rigid starting materials.

The measurement comprises three steps:

- a first step after automatic detection of the surface of the sample, where the spindle moves at a measuring speed of 0.1 mm/second, and penetrates into the composition according to the invention or the butter to a penetration depth of 0.3 mm, and the software notes the maximum force value reached;

- a second step, known as relaxation, where the spindle remains in this position for one second and the force is noted after 1 second of relaxation; and finally

- a third step, known as withdrawal, where the spindle returns to its original position at a speed of 1 mm/second, and the withdrawal energy of the spindle (negative force) is noted.

The hardness value measured during the first step corresponds to the maximum compression force measured in newtons divided by the area of the texturometer cylinder expressed in mm ² in contact with the butter or the composition according to the invention. The hardness value obtained is expressed in megapascals or MPa.

According to a preferred mode of the invention, the particular butter(s) are of plant origin, such as those described in Ullmann's Encyclopedia of Industrial Chemistry ("Fats and Fatty Oils", A. Thomas, published on 15/06/2000, DOI: 10.1002/14356007.a10_173, point 13.2.2.2. Shea Butter, Borneo Tallow, and Related Fats (Vegetable Butters)).

Mention may be made more particularly of shea butter, Karite Nilotica butter (Butyrospermum parkii), galam butter, (Butyrospermum parkii), Borneo butter or fat or tengkawang tallow (Shorea stenoptera), shorea butter, illipe butter, madhuca butter or Bassia madhuca longifolia butter, mowrah butter (Madhuca latifolia), katiau butter (Madhuca mottleyana), phulwara butter (M. butyracea), mango butter (Mangifera indica), murumuru butter (Astrocaryum murumuru), kokum butter (Garcinia indica), ucuuba butter (Virola sebifera), tucuma butter, painya butter (Kpangnan) (Pentadesma butyracea), coffee butter (Coffea arabica), apricot butter (Prunus armeniaca), macadamia butter (Macadamia ternifolia), grapeseed butter (Vitis vinifera), avocado butter (Persea gratissima), olive butter (Olea europaea), sweet almond butter (Prunus amygdalus dulcis), cocoa butter (Theobroma cacao) and sunflower butter.

According to one preferred mode of the invention, the weight content of Ci ₆ fatty acid triglycerides, expressed relative to the total amount of fatty acid triglycerides in the butter(s) according to the invention, is less than 23%.

Preferentially, the butter(s) according to the invention are chosen from murumuru butter, ucuuba butter, shorea butter, illipe butter, shea butter and cupuagu butter, and even more preferentially from murumuru butter and ucuuba butter.

In one preferred variant of the invention, the weight content of Ci ₆ fatty acid triglycerides, expressed relative to the total amount of fatty acid triglycerides, ranges from 0 to 22%, better still from 0 to 15% and even better still from 2% to 12%. Composition B and/or B' used in the process of the invention preferably comprises one or more butters in an amount particularly inclusively between 1 % and 80% by weight, more particularly between 2% and 50% by weight, preferentially between 3% and 40% by weight and more preferentially between 5% and 25% by weight, relative to the total weight of the said composition.

Composition A and/or A' preferably comprises one or more oils in an amount particularly inclusively between 1 % and 80% by weight, relative to the total weight of the composition, more particularly between 5% and 60% by weight, preferentially between 10% and 40% by weight and more preferentially between 15% and 30% by weight, relative to the total weight of the said composition. According to another preferred embodiment of the invention, composition B and/or B' used in the process according to the invention comprises a mixture of one or more identical or different oils, as defined previously, and of one or more identical or different butters, as defined previously.

According to another particular embodiment of the invention, composition B and/or B' used in the process of the invention comprises one or more oils and one or more butters in which the amount [oil(s) + butter(s)] is inclusively between 1 % and 80% by weight, more particularly between 2% and 50% by weight, preferentially between 3% and 40% by weight and more preferentially between 5% and 25% by weight, relative to the total weight of composition B or B'.

According to another particular embodiment of the invention, composition A and/or A', which is preferably compact and anhydrous, comprises one or more oils and one or more butters in which the amount [oil(s) + butter(s)] is particularly inclusively between 1 % and 80% by weight relative to the total weight of the composition, more particularly between 5% and 60% by weight, preferentially between 10% and 40% by weight and more preferentially between 15% and 30% by weight, relative to the total weight of the said composition.

According to a particular embodiment of the invention, the dyeing process uses a composition B and/or B' and/or A and/or A' which also comprises one or more fatty substances c) or c'), respectively, other than the oil(s) and other than the butter(s) b) and b') as defined previously.

According to a particular embodiment of the invention, composition B and/or B' and/or A and/or A' comprises as third constituent c) or c'), respectively, one or more waxes, preferably of plant origin.

The waxes may be fatty alcohols or fatty esters that are solid at room temperature and at atmospheric pressure.

According to one particular embodiment of the invention, the composition comprises as third constituent one or more solid fatty alcohols, preferably of plant origin.

The fatty alcohols that are suitable for use in the invention are more particularly chosen from linear saturated alcohols comprising from 6 to 30 carbon atoms and preferably from 8 to 30 carbon atoms. Mention may be made, for example, of cetyl alcohol, stearyl alcohol and a mixture thereof (cetearyl alcohol).

As regards the solid esters of fatty acids and/or of fatty alcohols, mention may preferably be made of esters of saturated linear fatty acids and of saturated linear fatty alcohols, such as cetyl palmitate, stearyl stearate or cetyl stearate.

According to another particular embodiment of the invention, composition B and/or B' comprises as third constituent c) or c'), one or more waxes, other than the fatty alcohols and fatty esters mentioned above, preferably of plant origin. These (non-silicone) waxes are chosen especially from carnauba wax, candelilla wax, esparto wax, paraffin wax, ozokerite, plant waxes, such as olive tree wax, rice wax, hydrogenated jojoba wax or absolute flower waxes, such as the blackcurrant blossom essential wax sold by Bertin (France), or animal waxes, such as beeswaxes or modified beeswaxes (cerabellina); other waxes or waxy raw materials that can be used according to the invention are in particular marine waxes, such as that sold by Sophim under the reference M82, polyethylene waxes or polyolefin waxes in general.

According to another particular embodiment of the invention, composition B and/or B' and/or A and/or A' comprises one or more silicone waxes, resins or gums.

In the category of polydialkylsiloxanes, mention may be made of the waxes sold under the names Abil Wax ^® 9800 and 9801 by the company Goldschmidt, which are polydi(Cr C ₂ o)alkylsiloxanes.

The silicone gums that may be used in accordance with the invention are especially polydialkylsiloxanes and preferably polydimethylsiloxanes with high number-average molecular weights of between 200 000 and 1 000 000, used alone or as a mixture in a solvent. This solvent can be chosen from volatile silicones, polydimethylsiloxane (PDMS) oils, polyphenylmethylsiloxane (PPMS) oils, isoparaffins, polyisobutylenes, methylene chloride, pentane, dodecane or tridecane, or mixtures thereof.

Products that can be used more particularly in accordance with the invention are mixtures such as:

- the mixtures formed from a hydroxy-terminated polydimethylsiloxane or dimethiconol (CTFA), and from a cyclic polydimethylsiloxane, also known as cyclomethicone (CTFA), such as the product Q2 1401 sold by Dow Corning;

- mixtures of a polydimethylsiloxane gum and a cyclic silicone, such as the product SF 1214 Silicone Fluid from the company General Electric; this product is an SF 30 gum corresponding to a dimethicone, having a number-average molecular weight of 500 000, dissolved in the oil SF 1202 Silicone Fluid corresponding to decamethylcyclopentasiloxane;

- mixtures of two PDMSs with different viscosities, and more particularly of a PDMS gum and a PDMS oil, such as the product SF 1236 from the company General Electric. The product SF 1236 is a mixture of a gum SE 30 defined above, with a viscosity of 20 m ² /s and of an oil SF 96 with a viscosity of 5x10 ^"6 m ² /s. This product preferably comprises 15% of gum SE 30 and 85% of an oil SF 96.

The organopolysiloxane resins that may be used in accordance with the invention are crosslinked siloxane systems containing the following units:

R ₂ Si0 ₂ / ₂ , R3S1O1/2, RS1O3/2 and Si0 ₄ / ₂ ,

in which R represents an alkyl containing 1 to 16 carbon atoms. Among these products, the ones that are particularly preferred are those in which R denotes a C1-C4 lower alkyl group, more particularly methyl. Among these resins, mention may be made of the product sold under the name Dow Corning 593 or those sold under the names Silicone Fluid SS 4230 and SS 4267 by the company General Electric, which are silicones of dimethyl/trimethylsiloxane structure. Mention may also be made of the trimethyl siloxysilicate type resins sold especially under the names X22-4914, X21 -5034 and X21 -5037 by the company Shin-Etsu.

Preferably, the fatty substance(s) do(es) not comprise(s) any C ₂ -C ₃ oxyalkylene units or any glycerolated units.

Composition B and/or B' and/or A and/or A' used in the dyeing process according to the invention preferably comprises a content of fatty substances c) or c'), other than the oil(s) and butter(s) b) or b') as defined previously, ranging from 0.5% to 50% by weight, better still from 1 % to 30% by weight and even better still from 1 % to 20% by weight relative to the total weight of the said composition. d) surfactants

According to one embodiment of the invention, composition B and/or B' and the composition A and/or A' comprise one or more surfactants d) or d'), respectively. These surfactants may be chosen from nonionic, anionic, cationic and amphoteric surfactants.

The amphoteric surfactant(s) that may be used in the present invention may especially be optionally quaternized secondary or tertiary aliphatic amine derivatives, in which the aliphatic group is a linear or branched chain containing from 8 to 22 carbon atoms, the said amine derivatives containing at least one anionic group, for instance a carboxylate, sulfonate, sulfate, phosphate or phosphonate group.

Among the optionally quaternized secondary or tertiary aliphatic amine derivatives that may be used, as defined above, mention may be made of the compounds of respective structures (B1 ) and (B2) below:

R _a -C(0)-N(Z)-CH ₂ -(CH ₂ ) _m -N ⁺ (R _b )(R _c )-CH ₂ -C(0)-0-, M ⁺ , X ^" (B1 )

in which formula (B1 ):

• R _a represents a Ci ₀ -C ₃ o alkyl or alkenyl group derived from an acid R _a -C(0)-OH preferably present in hydrolysed copra oil, or a heptyl, nonyl or undecyl group;

· R _b represents a β-hydroxyethyl group; and

• R _c represents a carboxymethyl group;

• M ⁺ represents a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine; and

· X ^" represents an organic or mineral anionic counterion, preferably chosen from halides, acetates, phosphates, nitrates, (CrC ₄ )alkyl sulfates, (Ci-C ₄ )alkyl or (d- C ₄ )alkylaryl sulfonates, in particular methyl sulfate and ethyl sulfate;

• m is equal to 0, 1 or 2;

• Z represents a hydrogen atom or a hydroxyethyl or carboxymethyl group; or alternatively M ⁺ and X ^" are absent;

R _a -C(0)-N(Z)-CH ₂ -(CH ₂ ) _m -N(B)-B' (B2)

in which formula (B2):

• B represents the group -CH ₂ -CH ₂ -0-X';

• B' represents the group -(CH ₂ ) _Z Y\ with z = 1 or 2;

· X' represents the group -CH ₂ -C(0)-OH, -CH ₂ -C(0)-0-Z\ -CH ₂ -CH ₂ -C(0)-OH, -CH ₂ -

CH ₂ -C(0)-OZ', or a hydrogen atom;

• Y' represents the group -C(0)-OH, -C(0)-OZ\ -CH ₂ -CH(OH)-S0 ₃ H or the group - CH ₂ -CH(OH)-S0 ₃ -Z';

• Z' represents a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine;

• R _a ' represents a Ci ₀ -C ₃ o alkyl or alkenyl group of an acid R _a '-C(0)-OH preferably present in hydrolysed linseed oil or copra oil, an alkyl group, in particular of Ci ₇ and its iso form, or an unsaturated Ci ₇ group;

• m' is equal to 0, 1 or 2;

· Z represents a hydrogen atom or a hydroxyethyl or carboxymethyl group.

The compounds of this type are classified in the CTFA dictionary, 5th edition, 1993, under the names disodium cocoamphodiacetate, disodium lauroamphodiacetate, disodium caprylamphodiacetate, disodium capryloamphodiacetate, disodium cocoamphodipropionate, disodium lauroamphodipropionate, disodium caprylamphodipropionate, disodium capryloamphodipropionate, lauroamphodipropionic acid, cocoamphodipropionic acid and hydroxyethylcarboxymethylcocamidopropylamine.

Examples that may be mentioned include the cocoamphodiacetate sold by the company Rhodia under the trade name Miranol ^® C2M Concentrate or under the trade name Miranol ^® Ultra C 32 and the product sold by the company Chimex under the trade name Chimexane HA.

Use may also be made of compounds of formula (B'2):

R _a "-N(H)-CH(Y")-(CH ₂ ) _n -C(0)-NH-(CH ₂ ) _n '-N(R _d )-R _e (B'2)

in which formula (B'2):

• Y', represents the group -C(0)-OH, -C(0)-0-Z", -CH ₂ -CH(OH)-S0 ₃ H or the group - CH ₂ -CH(OH)-S0 ₃ -Z";

• R _d and R _e represent, independently of each other, a C C ₄ alkyl or hydroxyalkyl radical;

· Z" represents a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine; • R _a " represents a C10-C30 alkyl or alkenyl group of an acid R _a "C(0)-OH preferably present in copra oil or in hydrolysed linseed oil;

• n and n' denote, independently of each other, an integer ranging from 1 to 3.

Among the compounds of formula (B'2), mention may be made of the compound classified in the CTFA dictionary under the name sodium diethylaminopropyl cocoaspartamide and sold by the company Chimex under the name Chimexane HB.

Among the amphoteric surfactants, mention may also be made of betaine surfactants, which are preferably chosen from the compounds of formula (I), and also the optional organic or mineral acid or base salts thereof, and solvates thereof such as hydrates:

which formula (I):

• R ¹ denotes a saturated or unsaturated, linear or branched hydrocarbon-based chain, comprising from 6 to 100 carbon atoms and in particular from 6 to 50 carbon atoms, which may be interrupted with one or more heteroatoms, divalent groups, or combinations thereof chosen from -0-, -C(O)- and -N(R)-; with R denoting a hydrogen atom or a CrC ₄ alkyl radical, and R ¹ also possibly being interrupted with an arylene group or terminated with an aryl group;

• R ² and R ³ , which may be identical or different, in particular R ² and R ³ are identical, denote a (CrC ₆ )alkyl group; preferably, R ² and R ³ represent a methyl group;

• R ⁴ denotes a linear or branched, preferably linear, divalent hydrocarbon-based radical, comprising from 1 to 10 and preferably from 1 to 5 carbon atoms, optionally substituted in particular with one or more hydroxyl groups;

• Z denotes a heteroatom or a divalent group chosen from -O- and -N(R)- with R as defined previously;

• n denotes a number equal to 1 or 2;

• m denotes an integer equal to 0 or 1 ;

• G ^" denotes an anionic radical chosen from carboxylates, sulfates, sulfonates, phosphates and phosphonates ( ^* -C(0)-0 ^" , ^* -S(0) ₂ -0 ^" , ^* -0-S(0) ₂ -0 ^" , ^* -P(0) ₂ -0 ^" , ^* - P(0)-0 ₂ ^" , ^* -P(OH)-0 ^" , ^** =P(0)-0 ^" and ^** =P-0 ^" ; with " ^* -" denoting the point of attachment of the anionic radical to the rest of the molecule via Z or R ⁴ when n is 1 , and " ^** =" representing the two points of attachment of the anionic radical via Z or R ⁴ when n is 2); it being understood that: - when n is 2, the radicals R ¹ R ² R ³ N ⁺ -R'-(Z) _m - are identical or different, preferably identical; and

- the surfactant of formula (I) being electrically neutral, it may comprise anionic and/or cationic counterions to produce the electrical neutrality of the molecule. The term "unsaturated" hydrocarbon-based chain means a hydrocarbon-based chain which comprises one or more double bonds and/or one or more triple bonds, the said bonds possibly being conjugated or non-conjugated.

The term "alkyl radical' means a saturated, linear or branched hydrocarbon-based radical, preferably of Ci-C ₈ .

The term "alkenyl radical means a linear or branched, preferably C ₂ -C ₈ , hydrocarbon- based radical; which is unsaturated, comprising one or more conjugated or non-conjugated double bonds.

The term "alkoxy radical means an alkyl-oxy radical for which the alkyl radical is a linear or branched C Ci ₆ and preferentially Ci-C ₈ hydrocarbon-based radical.

The term "aryP' radical means a fused or non-fused monocyclic or polycyclic carbon- based group comprising from 6 to 22 carbon atoms, and in which at least one ring is aromatic; preferentially, the aryl radical is a phenyl, biphenyl, naphthyl, indenyl, anthracenyl or tetrahydronaphthyl.

The term "arylene" radical means a fused or non-fused monocyclic or polycyclic carbon- based divalent radical or comprising from 6 to 22 carbon atoms, and in which at least one ring is aromatic; preferentially phenylene and more preferentially 1 ,3- or 1 ,4-phenylene.

The term "optionally substituted" attributed to the radical in question means that the said radical may be substituted with one or more radicals chosen from the following radicals: i) hydroxyl, ii) CrC ₄ alkoxy, iii) acylamino, iv) amino optionally substituted with one or two identical or different d-C ₄ alkyl radicals, the 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.

The term "organic or mineral acid salt" more particularly means salts chosen from a salt derived from i) hydrochloric acid HCI, ii) hydrobromic acid HBr, iii) sulfuric acid H ₂ S0 ₄ , iv) alkylsulfonic acids: Alk-S(0) ₂ OH such as methanesulfonic acid and ethanesulfonic acid; v) arylsulfonic acids: Ar-S(0) ₂ OH 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(0)OH such as methoxysulfinic acid and ethoxysulfinic acid; xi) aryloxysulfinic acids such as tolueneoxysulfinic acid and phenoxysulfinic acid; xii) phosphoric acid H ₃ P0 ₄ ; xiii) acetic acid CH ₃ C(0)-OH; xiv) triflic acid CF ₃ S0 ₃ H; and xv) tetrafluoroboric acid HBF ₄ .

The term "organic or mineral base salt" more particularly means salts chosen from a salt derived from basifying agents as defined in "Additional basifying agents" hereinbelow.

The term "anionic counterion" means an anion or an anionic group derived from an organic or mineral acid salt which counterbalances the cationic charge of the dye; more particularly, the anionic counterion is chosen from: i) halides such as chloride or bromide; ii) nitrates; iii) sulfonates, including Ci-C ₆ alkylsulfonates: Alk-S(0) ₂ 0 ^" such as methanesulfonate or mesylate and ethanesulfonate; iv) arylsulfonates: Ar-S(0) ₂ 0 ^" such as benzenesulfonate and toluenesulfonate or tosylate; v) citrate; vi) succinate; vii) tartrate; viii) lactate; ix) alkyl sulfates: Alk-0-S(0)0 ^" such as methyl sulfate and ethyl sulfate; x) aryl sulfates: Ar-0-S(0)0 ^" such as benzene sulfate and toluene sulfate; xi) alkoxy sulfates: Alk-O- S(0) ₂ 0 ^" such as methoxy sulfate and ethoxy sulfate; xii) aryloxy sulfates: Ar-0-S(0) ₂ 0 ^" , xiii) phosphates 0=P(OH) ₂ -0 ^" _, 0=P(0 ^" ) ₂ -OH, 0=P(0 ^" ) ₃ , HO-[P(0)(0 ^" )] _w -P(0)(0 ^" ) ₂ with w being an integer; xiv) acetate; xv) triflate; and xvi) borates such as tetrafluoroborate, xvii) disulfate (0=) ₂ S(0 ^" ) ₂ or S0 ₄ ^2" and monosulfate HS0 ₄ ^" ; the anionic counterion, derived from an 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 can 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 betaine surfactant which contains two positive charges either may contain two "singly charged" anionic counterions or may contain a "doubly charged" anionic counterion such as (0=) ₂ S(0) ₂ or 0=P(0 ^" ) ₂ -OH.

In particular, the cationic counterion(s) are chosen from alkali metals such as Na or K or alkaline-earth metals such as Mg or Ca, or organic cations such as ammonium or mono/di/tri(Ci-C ₆ )alkylammonium, and/or the anionic counterion(s) are chosen from halides such as chloride or alkylsulfonates such as mesylates.

More preferentially, the optional cationic counterion(s) are chosen from alkali metals such as Na or K or alkaline-earth metals such as Mg or Ca, and/or the anionic counterion(s) are chosen from halides such as chloride or alkylsulfonates such as mesylates. According to a preferred embodiment of the invention, the betaine surfactant(s) are chosen from the surfactants of formula (I) in which n is equal to 1 and G ^" denotes an anionic radical chosen from ^* -C(0)-0 ^" and ^* -S(0) ₂ -0 ^" .

According to an advantageous embodiment of the invention, the betaine surfactant(s) are chosen from the surfactants of formula (I) in which R ⁴ denotes a linear C1-C5 divalent alkylene radical optionally substituted with a hydroxyl group, such as -CH ₂ -CH ₂ -CH ₂ -, -CH ₂ - CH(OH)-CH ₂ - or -CH ₂ -CH ₂ -.

According to a preferred embodiment of the invention, the betaine surfactant(s) are chosen from the surfactants of formula (I) in which m is 1 and Z represents an oxygen atom or a group -N(R)- with R as defined previously. More preferentially, when m is 1 , then Z represents an oxygen atom.

According to another preferred embodiment of the invention, the betaine surfactant(s) are chosen from the surfactants of formula (I) in which m is 0.

According to another preferred embodiment of the invention, the betaine surfactant(s) are chosen from the surfactants of formula (I) in which R ¹ denotes a group chosen from i) C ₆ - C ₃ o alkyl; ii) C ₆ -C ₃ o alkenyl; -alkyl(C6-C ₃ o)-amido-(Ci-C ₄ )alkyl or -alkenyl(C ₆ -C ₃ o)-amido-(Ci- C ₄ )alkyl, with amido representing a group -C(0)-N(R)- and R being as defined previously. Particularly, R denotes a hydrogen atom.

More particularly, R ¹ denotes a linear or branched, preferably linear, C ₆ -C ₃ o alkyi radical.

Among the abovementioned amphoteric surfactants, it is preferred to use (C ₈ -C ₂ o alkyl)betaines such as cocoylbetaine, (C ₈ -C ₂ o alkyl)amido(C ₂ -C ₈ alkyl)betaines such as cocoylamidopropylbetaine, and mixtures thereof.

More preferentially, the amphoteric surfactant(s) are chosen from cocoylamidopropylbetaine and cocoylbetaine.

The term "anionic surfactant" means a surfactant comprising, as ionic or ionizable groups, only anionic groups. These anionic groups are preferably chosen from the following groups:

-C(0)-OH, -C(0)-0 ^" , -SO3H , -S(0) ₂ 0 ^" , -OS(0) ₂ OH, -OS(0) ₂ 0 ^" , -P(0)OH ₂ , -P(0) ₂ 0 ^" , -P(0)0 ₂ ^" , -P(OH) ₂ , =P(0)OH, -P(OH)0 ^" , =P(0)0 ^" , =POH, =PO ^" ; the anionic parts comprising a cationic counterion such as those of an alkali metal, an alkaline-earth metal or an ammonium.

As examples of anionic surfactants that may be used in the composition according to the invention, mention may be made of alkyi sulfates, alkyi ether sulfates, alkylamido ether sulfates, alkylaryl polyether sulfates, monoglyceride sulfates, alkylsulfonates, alkylamidesulfonates, alkylarylsulfonates, oolefin sulfonates, paraffin sulfonates, alkyi sulfosuccinates, alkyi ether sulfosuccinates, alkylamide sulfosuccinates, alkyi sulfoacetates, acylsarcosinates, acylglutamates, alkyi sulfosuccinamates, acylisethionates and N- acyltaurates, polyglycoside polycarboxylic acid and alkyi monoester salts, acyl lactylates, salts of D-galactoside uronic acids, salts of alkyi ether carboxylic acids, salts of alkylaryl ether carboxylic acids, salts of alkylamido ether carboxylic acids, and the corresponding non- salified forms of all these compounds; the alkyi and acyl groups of all these compounds comprising from 6 to 24 carbon atoms and the aryl group denoting a phenyl group.

These compounds can be oxyethylenated and then preferably comprise from 1 to 50 ethylene oxide units.

The salts of C ₆ -C ₂₄ alkyi monoesters of polyglycoside-polycarboxylic acids may be chosen from C ₆ -C ₂₄ alkyi polyglycoside-citrates, C ₆ -C ₂₄ alkyi polyglycoside-tartrates and C ₆ - C ₂₄ alkyi polyglycoside-sulfosuccinates.

When the anionic surfactant(s) are in salt form, they may be chosen from alkali metal salts such as the sodium or potassium salt and preferably the sodium salt, ammonium salts, amine salts and in particular amino alcohol salts or alkaline-earth metal salts such as the magnesium salts.

Examples of amino alcohol salts that may especially be mentioned include monoethanolamine, diethanolamine and triethanolamine salts, monoisopropanolamine, diisopropanolamine or triisopropanolamine salts, 2-amino-2-methyl-1 -propanol salts, 2- amino-2-methyl-1 ,3-propanediol salts and tris(hydroxymethyl)aminomethane salts. Alkali metal or alkaline-earth metal salts, and in particular sodium or magnesium salts, are preferably used.

Among the anionic surfactants mentioned, use is preferably made of (C ₆ -C ₂ 4)alkyl sulfates, (C ₆ -C ₂ 4)alkyl ether sulfates comprising from 2 to 50 ethylene oxide units, in particular in the form of alkali metal, ammonium, amino alcohol and alkaline-earth metal salts, or a mixture of these compounds.

In particular, it is preferred to use (Ci ₂ -C ₂ o)alkyl sulfates, (Ci ₂ -C ₂₀ )alkyl ether sulfates comprising from 2 to 20 ethylene oxide units, especially in the form of alkali metal, ammonium, amino alcohol and alkaline-earth metal salts, or a mixture of these compounds. Better still, it is preferred to use sodium lauryl ether sulfate containing 2.2 mol of ethylene oxide.

According to another particular embodiment of the invention, the ingredient d) or d') represents one or more cationic surfactants.

The cationic surfactant(s) that may be used in the composition according to the invention comprise, for example, optionally polyoxyalkylenated primary, secondary or tertiary fatty amine salts, quaternary ammonium salts, and mixtures thereof.

Among the tertiary fatty amines, mention may be made of oleylamidopropyldimethylamine.

Examples of quaternary ammonium salts that may especially be mentioned include:

- those corresponding to the general formula (II) below:

in which formula (II):

^■ R ₈ to Ri i , which may be identical or different, represent a linear or branched, saturated or unsaturated aliphatic group comprising from 1 to 30 carbon atoms, or an aromatic group such as aryl or alkylaryl, it being understood that at least one of the groups R ₈ to Rn comprises from 8 to 30 carbon atoms and preferably from 12 to 24 carbon atoms; and

^■ X ^" represents an organic or mineral anionic counterion, such as that chosen from halides, acetates, phosphates, nitrates, (CrC ₄ )alkyl sulfates, (CrC ₄ )alkyl or (d-

C ₄ )alkylaryl sulfonates, in particular methyl sulfate and ethyl sulfate.

The aliphatic groups of R ₈ to Rn may also comprise heteroatoms especially such as oxygen, nitrogen, sulfur and halogens.

The aliphatic groups of R ₈ to Rn are chosen, for example, from C1-C30 alkyl, C1-C30 alkoxy, polyoxy(C ₂ -C ₆ )alkylene, C1-C30 alkylamide, (Ci ₂ -C ₂₂ )alkylamido(C ₂ -C ₆ )alkyl, (Ci ₂ - C ₂₂ )alkyl acetate, and Ci-C ₃₀ hydroxyalkyl groups; X ^" is an anionic counterion chosen from halides, phosphates, acetates, lactates, (CrC ₄ )alkyl sulfates, and (Ci-C ₄ )alkyl- or (d- C ₄ )alkylarylsulfonates.

Among the quaternary ammonium salts of formula (II), preference is given firstly to tetraalkylammonium chlorides, for instance dialkyldimethylammonium or alkyltrimethylammonium chlorides in which the alkyl group contains approximately from 12 to 22 carbon atoms, in particular behenyltrimethylammonium chloride, distearyldimethylammonium chloride, cetyltrimethylammonium chloride, benzyldimethyl- stearylammonium chloride, or else, secondly, distearoylethylhydroxyethylmethylammonium methosulfate, dipalmitoylethylhydroxyethyl-ammonium methosulfate or distearoylethyl- hydroxyethylammonium methosulfate, or else, lastly, palmitylamidopropyltrimethylammonium chloride;

- quaternary ammonium salts of imidazoline, for instance those of formula (III) below:

in which formula

■ Ri2 represents an alkenyl or alkyl group comprising from 8 to 30 carbon atoms, for example fatty acid derivatives of tallow;

^■ Ri ₃ represents a hydrogen atom, a C C ₄ alkyl group or an alkenyl or alkyl group comprising from 8 to 30 carbon atoms;

^■ Ri ₄ represents a C C ₄ alkyl group;

■ Ri ₅ represents a hydrogen atom or a C C ₄ alkyl group;

^■ X ^" represents an organic or mineral anionic counterion, such as that chosen from halides, phosphates, acetates, lactates, (Ci-C ₄ )alkyl sulfates, (Ci-C ₄ )alkyl or (d- C ₄ )alkylaryl sulfonates.

R-I2 and Ri ₃ preferably denote a mixture of alkenyl or alkyl groups containing from 12 to 21 carbon atoms, for example fatty acid derivatives of tallow, R ₁₄ denotes a methyl group, and Ri ₅ denotes a hydrogen atom. Such a product is sold, for example, under the name Rewoquat® W 75 by the company Rewo;

- quaternary diammonium or triammonium salts, particularly of formula (IV) below:

^17 ^19

R ₁₆ N— (CH ₂ ) ₃ — N— R ₂₁

X I X

^R 18 R ₂ o ₍ | _V)

in which formula (IV): ^■ R-16 denotes an alkyl group comprising approximately from 16 to 30 carbon atoms, which is optionally hydroxylated and/or interrupted with one or more oxygen atoms;

^■ R-I7 is chosen from hydrogen, an alkyl group comprising from 1 to 4 carbon atoms or a group -(CH ₂ ) ₃ -N ⁺ (R _16a )(R _17a )(R _18a ), X ^" ;

^■ R _16a , Ri7a, Risa, Ri8, Ri9, R20 and R21 , which may be identical or different, are chosen from hydrogen and an alkyl group comprising from 1 to 4 carbon atoms; and

^■ X ^" , which may be identical or different, represents an organic or mineral anionic counterion, such as that chosen from halides, acetates, phosphates, nitrates, alkyl(CrC ₄ ) sulfates, alkyl(Ci-C ₄ )- or alkyl(Ci-C ₄ )aryl-sulfonates, more particularly methyl sulfate and ethyl sulfate.

Such compounds are, for example, Finquat CT-P, provided by the company Finetex (Quaternium 89), and Finquat CT, provided by the company Finetex (Quaternium 75);

• quaternary ammonium salts containing one or more ester functions, such as those of formula (V) below:

in which formula (V):

^■ R ₂ 2 is chosen from CrC ₆ alkyl groups and CrC ₆ hydroxyalkyl or CrC ₆ dihydroxyalkyl groups;

■ R23 is chosen from:

O

- the group ^{Ra6 C} ,

- linear or branched, saturated or unsaturated C1-C22 hydrocarbon-based groups R ₂₇ ,

- a hydrogen atom,

■ R25 is chosen from:

O

- the group ^R28 ^

- linear or branched, saturated or unsaturated Ci-C ₆ hydrocarbon-based groups

- a hydrogen atom,

■ R ₂₄ , R26 and R ₂ 8, which may be identical or different, are chosen from linear or branched, saturated or unsaturated C7-C21 hydrocarbon-based groups;

^■ r, s and t, which may be identical or different, are integers ranging from 2 to 6,

^■ r1 and t1 , which may be identical or different, are equal to 0 or 1 , with r2+r1 =2r and t1 +t2=2t, ^■ y is an integer ranging from 1 to 10,

^■ x and z, which may be identical or different, are integers ranging from 0 to 10,

^■ X ^" represents an organic or mineral anionic counterion,

with the proviso that the sum x + y + z is from 1 to 15, that when x is 0 then R ₂ 3 denotes R ₂ 7, and that when z is 0 then R ₂₅ denotes R ₂₉ .

The alkyl groups R ₂₂ may be linear or branched, and more particularly linear.

Preferably, R ₂₂ denotes a methyl, ethyl, hydroxyethyl or dihydroxypropyl group, and more particularly a methyl or ethyl group.

Advantageously, the sum x + y + z is from 1 to 10.

When R ₂₃ is a hydrocarbon-based group R ₂₇ , it may be long and contain from 12 to 22 carbon atoms, or may be short and contain from 1 to 3 carbon atoms.

When R ₂₅ is an R ₂₉ hydrocarbon-based group, it preferably contains 1 to 3 carbon atoms.

Advantageously, R ₂₄ , R ₂₆ and R ₂₈ , which may be identical or different, are chosen from linear or branched, saturated or unsaturated Cn-C ₂ i hydrocarbon-based groups, and more particularly from linear or branched, saturated or unsaturated Cn-C ₂ i alkyl and alkenyl groups.

Preferably, x and z, which may be identical or different, are equal to 0 or 1 .

Advantageously, y is equal to 1.

Preferably, r, s and t, which may be identical or different, are equal to 2 or 3, and even more particularly are equal to 2.

The anionic counterion X ^" is preferably a halide, such as chloride, bromide or iodide; a (CrC ₄ )alkyl sulfate or a (CrC ₄ )alkyl- or a (Ci-C ₄ )alkylarylsulfonate. However, it is possible to use methanesulfonate, phosphate, nitrate, tosylate, an anion derived from an organic acid, such as acetate or lactate, or any other anion that is compatible with the ammonium containing an ester function.

The anionic counterion X ^" is even more particularly chloride, methyl sulfate or ethyl sulfate.

Use is made more particularly in the composition according to the invention of the ammonium salts of formula (V) in which:

- R ₂₂ denotes a methyl or ethyl group,

- x and y are equal to 1 ,

- z is equal to 0 or 1 ,

- r, s and t are equal to 2,

- R ₂₃ is chosen from:

O

• the group ^{Ra6 C}

• methyl, ethyl or Ci ₄ -C ₂₂ hydrocarbon-based groups,

• a hydrogen atom,

- R ₂₅ is chosen from: o

• the group ²⁸

• a hydrogen atom,

- R ₂ 4, R26 and R ₂ 8, which may be identical or different, are chosen from linear or branched, saturated or unsaturated C13-C17 hydrocarbon groups, and preferably from linear or branched, saturated or unsaturated C13-C17 alkyl and alkenyl groups.

Advantageously, the hydrocarbon-based radicals are linear.

Among the compounds of formula (V), examples that may be mentioned include salts, especially the chloride or methyl sulfate, of diacyloxyethyldimethylammonium, diacyloxyethylhydroxyethylmethylammonium,

monoacyloxyethyldihydroxyethylmethylammonium, triacyloxyethylmethylammonium or monoacyloxyethylhydroxyethyldimethylammonium, and mixtures thereof. The acyl groups preferably contain 14 to 18 carbon atoms and are obtained more particularly from a plant oil, such as palm oil or sunflower oil. When the compound contains several acyl groups, these groups may be identical or different.

These products are obtained, for example, by direct esterification of triethanolamine, triisopropanolamine, an alkyldiethanolamine or an alkyldiisopropanolamine, which are optionally oxyalkylenated, with fatty acids or with fatty acid mixtures of vegetable or animal origin, or by transesterification of the methyl esters thereof. This esterification is followed by a quaternization by means of an alkylating agent such as an alkyl halide, preferably methyl or ethyl halide, a dialkyl sulfate, preferably dimethyl or diethyl sulfate, methyl methanesulfonate, methyl para-toluenesulfonate, glycol chlorohydrin or glycerol chlorohydrin.

Such compounds are sold, for example, under the names Dehyquart® by the company Henkel, Stepanquat® by the company Stepan, Noxamium® by the company Ceca or Rewoquat® WE 18 by the company Rewo-Witco.

The composition according to the invention may contain, for example, a mixture of quaternary ammonium monoester, diester and triester salts with a weight majority of diester salts.

It is also possible to use the ammonium salts containing at least one ester function that are described in patents US-A-4 874 554 and US-A-4 137 180.

Use may be made of behenoylhydroxypropyltrimethylammonium chloride sold by KAO under the name Quatarmin BTC 131.

Preferably, the ammonium salts containing at least one ester function contain two ester functions.

Among the cationic surfactants that may be present in the composition according to the invention, it is more particularly preferred to choose cetyltrimethylammonium, behenyltrimethylammonium and dipalmitoylethylhydroxyethylmethylammonium salts, and mixtures thereof, and more particularly behenyltrimethylammonium chloride, cetyltrimethylammonium chloride, dipalmitoylethylhydroxyethylammonium methosulfate and oleylamidopropyldimethylamine, and mixtures thereof.

The term "nonionic" surfactant means a surfactant that does not bear any anionic or cationic charge. Examples of nonionic surfactants that may be used in the composition used according to the invention are described, for example, in the Handbook of Surfactants by M.R. Porter, published by Blackie & Son (Glasgow and London), 1991 , pp. 1 16-178. They are especially chosen from alcohols, a-diols and (CrC ₂ o)alkylphenols, these compounds being polyethoxylated, polypropoxylated and/or polyglycerolated, and containing at least one fatty chain comprising, for example, from 8 to 18 carbon atoms, it being possible for the number of ethylene oxide and/or propylene oxide groups to especially range from 2 to 50, and for the number of glycerol groups to especially range from 2 to 30.

Mention may also be made of copolymers of ethylene oxide and propylene oxide, optionally oxyethylenated sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyalkylenated fatty acid esters, optionally oxyalkylenated alkyl polyglycosides, alkyl glucoside esters, derivatives of N-alkyl glucamine and of N-acyl methylglucamine, aldobionamides and amine oxides.

The nonionic surfactants are chosen more particularly from mono- or polyoxyalkylenated or mono- or polyglycerolated nonionic surfactants. The oxyalkylene units are more particularly oxyethylene or oxypropylene units, or a combination thereof, preferably oxyethylene units.

Examples of oxyalkylenated nonionic surfactants that may be mentioned include:

• oxyalkylenated (C ₈ -C ₂ 4)alkylphenols;

· saturated or unsaturated, linear or branched, oxyalkylenated C ₈ -C ₃ o alcohols;

• saturated or unsaturated, linear or branched, oxyalkylenated C ₈ -C ₃ o amides;

• esters of saturated or unsaturated, linear or branched, C ₈ -C ₃ o acids and of polyethylene glycols;

• polyoxyethylenated esters of saturated or unsaturated, linear or branched, C ₈ -C ₃ o acids and of sorbitol;

• saturated or unsaturated, oxyethylenated plant oils;

• condensates of ethylene oxide and/or of propylene oxide, inter alia, alone or as mixtures;

• oxyethylenated and/or oxypropylenated silicones.

The surfactants contain a number of moles of ethylene oxide and/or of propylene oxide of between 1 and 100, preferably between 2 and 50 and preferably between 2 and 30.

Advantageously, the nonionic surfactants do not comprise any oxypropylene units.

In accordance with one preferred embodiment of the invention, the oxyalkylenated nonionic surfactants are chosen from oxyethylenated C ₈ -C ₃₀ alcohols comprising from 1 to 100 mol of ethylene oxide; polyoxyethylenated esters of linear or branched, saturated or unsaturated C ₈ -C ₃₀ acids and of sorbitol comprising from 1 to 100 mol of ethylene oxide. As examples of monoglycerolated or polyglycerolated nonionic surfactants, monoglycerolated or polyglycerolated C ₈ -C ₄ o alcohols are preferably used.

In particular, the monoglycerolated or polyglycerolated C ₈ -C ₄₀ alcohols correspond to formula (VI) below:

R2 ₉ 0-[CH ₂ -CH(CH ₂ OH)-0] _m -H (VI)

in which formula (VI):

^■ R ₂ 9 represents a linear or branched C ₈ -C ₄₀ and preferably C ₈ -C ₃ o alkyl or alkenyl radical; and

^■ m represents a number ranging from 1 to 30 and preferably from 1 to 10.

As examples of compounds of formula (A8) that are suitable within the context of the invention, mention may be made of lauryl alcohol containing 4 mol of glycerol (INCI name: Polyglyceryl-4 Lauryl Ether), lauryl alcohol containing 1 .5 mol of glycerol, oleyl alcohol containing 4 mol of glycerol (INCI name: Polyglyceryl-4 Oleyl Ether), oleyl alcohol containing 2 mol of glycerol (INCI name: Polyglyceryl-2 Oleyl Ether), cetearyl alcohol containing 2 mol of glycerol, cetearyl alcohol containing 6 mol of glycerol, oleocetyl alcohol containing 6 mol of glycerol, and octadecanol containing 6 mol of glycerol.

The alcohol of formula (VI) may represent a mixture of alcohols in the same way that the value of m represents a statistical value, which means that, in a commercial product, several species of polyglycerolated fatty alcohols may coexist in the form of a mixture.

Among the monoglycerolated or polyglycerolated alcohols, it is more particularly preferred to use the C ₈ /Ci ₀ alcohol containing 1 mol of glycerol, the Ci ₀ Ci ₂ alcohol containing 1 mol of glycerol and the Ci ₂ alcohol containing 1.5 mol of glycerol.

Among the saturated or unsaturated, linear or branched C ₈ -C ₃₀ acid esters of polyoxyethylenated sorbitol, the ones that are preferred are those with a number of moles of ethylene oxide of less than or equal to 20, particularly comprising from 8 to 24 carbon atoms and more particularly from 8 to 18 carbon atoms. The fatty acids are especially chosen from lauric acid, palmitic acid, oleic acid and stearic acid, and preferably from lauric acid and stearic acid, and even more particularly lauric acid.

C ₈ -C ₂₄ fatty acid monoesters of oxyethylenated sorbitan are preferably used. The number of moles of ethylene oxide is preferably less than 10 and more particularly ranges from 3 to 8 mol of ethylene oxide and in particular is equal to 4.

The preferred sorbitan esters are sorbitan monolaurate oxyethylenated with 4 mol of ethylene oxide (4 EO) or polysorbate 21 , sorbitan monostearate oxyethylenated with 4 mol of ethylene oxide (4 EO) or polysorbate 61 , and sorbitan monooleate oxyethylenated with 5 mol of ethylene oxide (5 EO) or polysorbate 81 .

Polysorbate 21 is particularly preferred and is sold especially under the name Tween 21 by the company Uniqema.

According to the invention, the composition may advantageously comprise mixtures of oxyethylenated sorbitan esters and especially polysorbate 21 with polysorbate 20 (sorbitan monolaurate oxyethylenated with 20 EO).

Preferably, the surfactant(s) are chosen from nonionic, cationic and anionic surfactants and are particularly chosen from nonionic and anionic surfactants.

More particularly, the surfactant(s) present in composition B and/or B' are chosen from nonionic surfactants. Preferably, the nonionic surfactant(s) are monooxyalkylenated or polyoxyalkylenated, particularly monooxyethylenated or polyoxyethylenated, or monooxypropylenated or polyoxypropylenated, nonionic surfactant(s), or a combination thereof, more particularly monooxyethylenated or polyoxyethylenated.

More preferentially, the nonionic surfactants are chosen from polyoxyethylenated sorbitol esters and polyoxyethylenated fatty alcohols, and mixtures thereof.

According to one variant of the invention, composition B and/or B' and/or A and/or A' and/or C and/or C involves one or more surfactants chosen from nonionic surfactants, in particular monooxyalkylenated or polyoxyalkylenated nonionic surfactants, more particularly chosen from polyoxyethylenated saturated or unsaturated, linear or branched C ₈ -C ₃₀ acid esters of sorbitol as defined previously; anionic surfactants, in particular of alkyl sulfate type as defined previously, in particular alkali metal or alkaline-earth metal lauryl ether sulfate.

Composition B and/or B' preferably contains from 1 % to 60% by weight, preferably from 5% to 50% by weight and better still from 10% to 40% by weight of surfactant(s), relative to the total weight of the said composition.

Composition A and/or A' of the invention preferably contains from 0.1 % to 30% by weight, preferably from 0.5% to 20% by weight and better still from 1 % to 10% by weight of surfactant(s), relative to the total weight of the said composition.

Water.

Composition B and/or B' of the invention as defined previously comprises water. This water constitutes all or part of an aqueous phase. The term "aqueous phase" means a phase which comprises essentially water, and also comprises other ingredients that are water-miscible or water-soluble at room temperature and at atmospheric pressure. As liquids or solids that may be present in the aqueous phase, mention may be made of: polar or polar protic organic solvents as defined below, salts of mineral or organic acids or bases, or water-soluble cosmetic active agents.

Composition B and/or B' of the invention contains water preferably in an amount ranging from 5% to 90% by weight, better still from 20% to 80% and particularly from 40% to 75% by weight relative to the total weight of the said composition. The compositions

The composition(s) used in the process of the invention are cosmetic, i.e. they are cosmetically acceptable and therefore suitable for use for application to keratin fibres, especially human keratin fibres such as the hair. According to a particular embodiment of the invention, composition B and/or B' used in the process of the invention contains one or more "mordants", i.e. metal salts conventionally used in "mordanting" (see for example Ullmann's Encyclopedia of Industrial Chemistry ("Textile Dyeing", Herbert Leube et al., DOI: 10.1002/14356007. a26_351 , and in particular point 4.8.2, p. 72 ; ibid, "Metal-complex dyes", Klaus Gryschtol et al., DOI: 10.1002/14356007.a16_299).

According to another particular embodiment of the invention, composition B and/or B' used in the process of the invention does not contain any "mordants". Preferentially, the dyeing process of the invention does not use any mordants.

As mentioned previously, composition B and/or B' used in the process of the invention may be derived from the mixing of a composition A and/or A' mixed with water or an aqueous composition, preferably to form a poultice. Composition A and A ':

Compositions A and/or A' may be compacted or in non-compacted powder form, and may be anhydrous or non-anhydrous.

Composition A and/or A' may comprise water or a mixture of water and also one or more organic solvents or a mixture of organic solvents.

Composition A and/or A' of the invention preferably comprises less than 3% by weight and preferably less than 2% by weight of water relative to the total weight of the composition, or even is free of water.

Preferably, compositions A and A' are anhydrous, i.e. they do not comprise any water other than the water associated with the starting materials included in its composition.

Compositions A or A' may be in the form of a powder.

They may also be in the form of a paste.

Composition A and/or A' according to the invention is preferentially in compact form. As emerges from the foregoing, the compact composition according to the invention is "solid".

- "solid" means the state of the composition at room temperature (25°C) and at atmospheric pressure (760 mmHg), i.e. a composition of high consistency, which conserves its form during storage. As opposed to "fluid" compositions, it does not flow under its own weight. It is advantageously characterized by a hardness as defined below.

- "compact composition" means that the composition consists of a mixture of products whose cohesion is at least partly provided by compacting or pressing during the manufacture. In particular, by carrying out a measurement using a TA.XT.plus Texture Analyser sold by Stable Micro Systems, the compact powder according to the invention can advantageously exhibit a resistance to pressure of between 0.2 and 2.5 kg and in particular between 0.8 and 1 .5 kg, with respect to the surface area of the spindle used (in the case in point, 7.07 mm ² ). The measurement of this resistance is performed by moving an SMS P/3 flat-headed cylindrical spindle over a distance of 1 .5 mm and at a speed of 0.5 mm/sec in contact with the powder. According to a preferred embodiment of the invention, composition A and/or A' is in compact form and in different forms as a function of the desired compacting, especially in the form of pebbles, in the form of stones, in the form of soaps, in the form of pyramids, in the form of cartons or in the form of plates. More preferentially, when the composition comprises b) or b') one or more oils and/or butters and/or fatty substances, it is in compact form.

The cosmetic composition A and/or A' of the invention may also be in other non- compact galenical forms, such as a lotion, a mousse, a cream or a gel, or in any other form that is suitable for dyeing keratin fibres. It may also be conditioned in a propellant-free pump- action bottle or under pressure in an aerosol container in the presence of a propellant and form a foam.

Preferably, composition i) is the form of a "poultice".

As mentioned previously, composition B and/or B' is derived from mixing between composition A and/or A', which is preferably compact and/or anhydrous, and an aqueous composition C and/or C and preferably water (only water) to give a mixture preferably in the form of a poultice. Use may thus be made of composition B comprising:

a) at least 10% by weight of henna powder as defined previously;

b) optionally at least one oil and/or butter as defined previously;

c) optionally at least one fatty substance other than the oil(s) or butters b);

d) optionally at least one surfactant; and

e) optionally other additional natural dyes as defined below;

and composition B' comprising: a') at least 10% by weight of powder of indigo-producing plant(s);

b') optionally at least one oil and/or butter as defined previously;

c') optionally at least one fatty substance other than the oil(s) or butters b);

d') optionally at least one surfactant; and

e") optionally other additional natural dyes as defined below.

To do this, compositions A and A' as defined previously are preferably in compact and/or anhydrous form comprising ingredients a) to e) and a') to e'), respectively, as defined previously and are mixed with an aqueous composition, and preferably mixed with water to obtain, respectively, a composition B and B' preferably in the form of a poultice with a pleasant, creamy consistency. When compositions A and A' are compact, they are broken down, respectively, in an aqueous composition C and C and preferentially compositions A and A' are compact and are broken down in water. The ratios of compositions A and A' according to the invention and of aqueous compositions C and C\ respectively, preferentially water, preferably range from 1 part by weight of composition A or A' per 1 part by weight of aqueous composition C or C and preferentially water (1 /1 ) to 1 part by weight of composition A or A' per 3 parts by weight of aqueous compositions C or C and preferentially water (1/3).

According to another particular embodiment of the invention, compositions B and/or B' comprise only ingredients of natural origin.

During the preparation of composition B or B', one or more identical or different clays, as defined below, may be added.

According to another preferred embodiment of the invention, composition B or B' is at a neutral pH close to 7 (preferably ranging from 6 to 8 and better still from 6.5 to 7.5).

Compositions A, A', B, B', and C or C may comprise one or more organic solvents. Examples of organic solvents that may be mentioned include Ci-C ₄ lower alkanols, such as ethanol and isopropanol; polyols and polyol ethers such as 2-butoxyethanol, propylene glycol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether and monomethyl ether, hexylene glycol, and also aromatic alcohols, for instance benzyl alcohol or phenoxyethanol.

The organic solvents are present in proportions preferably of between 0.1 % and 20% by weight approximately and even more preferentially between 0.5% and 10% by weight approximately, relative to the total weight of the composition under consideration.

Compositions A, A', C and/or C may comprise one or more surfactants such as those that may be present in composition B or B'.

Adjuvants: Compositions A, A', B, B', C and/or C of the invention may also contain various adjuvants conventionally used in hair dye compositions, such as anionic, cationic, nonionic, amphoteric and zwitterionic polymers or mixtures thereof, mineral or organic thickeners, and in particular anionic, cationic, nonionic and amphoteric polymeric associative thickeners, antioxidants, penetrants, sequestrants, fragrances, buffers, dispersants, conditioning agents other than the butters or oils of the invention, for instance ceramides, film-forming agents, preserving agents, opacifiers and mineral or organic thickeners such as clays.

According to a particular embodiment, compositions B, B', C and C are not in emulsion form. Preferably, in this embodiment, none of the compositions A, A', B, B', C and C contain surfactants.

According to another advantageous variant, compositions B, B', C and C are in emulsion form. Preferably, compositions B, B', C and C then contain surfactants.

The above adjuvants are generally present in an amount for each of them of between 0.01 % and 40% by weight relative to the weight of the composition, and preferably between 0.1 % and 20% by weight relative to the weight of the composition under consideration.

Needless to say, a person skilled in the art will take care to choose this or these optional additional compound(s) such that the advantageous properties intrinsically associated with the composition B or B' that is useful in the dyeing process in accordance with the invention are not, or are not substantially, adversely affected by the envisaged addition(s). d) Additional dyes:

Compositions A, A', B, B', C and/or C of the invention comprising the ingredients a) to d) and a') to d') as defined previously may also contain e) or e') one or more additional direct dyes other than the henna or indigo-producing plant powder a) or a').

These direct dyes are chosen, for example, from those conventionally used in direct dyeing, and among which mention may be made of any commonly used aromatic and/or non-aromatic dye such as neutral, acidic or cationic nitrobenzene direct dyes, neutral, acidic or cationic azo direct dyes, natural direct dyes, neutral, acidic or cationic quinone and in particular anthraquinone direct dyes, azine, triarylmethane, indoamine, methine, styryl, porphyrin, metalloporphyrin, phthalocyanine, cyanine and methine direct dyes, and fluorescent dyes.

Preferentially, compositions A, A', B, B', C and/or C of the invention may comprise one or more natural dyes other than henna and indigo-producing plant(s) a) as defined previously e) or e'), respectively. Among the natural direct dyes, mention may be made of juglone, isatin, curcumin, spinulosin, apigenidin and orceins. These natural dyes may be added in the form of defined compounds, extracts or plant parts. The said defined compounds from extracts or from plant parts are preferably in the form of powders, in particular fine powders whose particles have sizes identical to that of the henna and/or indigo-producing plant powder a) as defined previously.

The natural or non-natural direct dye(s), other than the henna and/or indigo-producing plant powder a), in the composition according to the invention particularly represent from 0.001 % to 10% by weight, relative to the total weight of the composition and even more preferentially from 0.05% to 5% by weight, relative to the total weight of the composition under consideration.

Preferably, composition B or B' of the invention does not contain any synthetic direct dyes, i.e. dyes that do not occur in nature.

Compositions A, A', B and/or B' comprising the ingredients a) to e) and a') to e') as defined previously and composition C and/or C according to the invention may also comprise as oxidation dye(s) one or more oxidation bases and/or one or more couplers conventionally used for the dyeing of keratin fibres.

Among the oxidation bases, mention may be made of para-phenylenediamines, bis(phenyl)alkylenediamines, para-aminophenols, bis-para-aminophenols, ortho- aminophenols and heterocyclic bases, and the addition salts thereof. Preferentially, compositions A, A', B, B', C and/or C of the invention do not contain any para-phenylenediamine(s).

Mention may in particular be made, among these couplers, of meta- phenylenediamines, meta-aminophenols, meta-diphenols, naphthalene couplers, heterocyclic couplers and addition salts thereof.

The oxidation base(s) present in the composition(s) are each generally present in an amount of between 0.001 % and 10% by weight, of the total weight of the dye composition(s).

Preferably, compositions A, A', B, B', C and/or C do not contain any oxidation dyes. pH of the compositions B, B', C and/or C

According to a particular mode of the invention, the pH of the aqueous compositions B and B' and also the pH of the aqueous compositions C and C is neutral, i.e. they have a pH of about 7 (preferably ranging from 6 to 8 and better still from 6.5 to 7.5).

In another particular mode of the invention, compositions B and B' used in the process of the invention and/or compositions C and C are acidic and preferably have a pH ranging from 3 to 6.5.

The pH of compositions B, B', C and/or C may be adjusted to the desired value by means of acidifying or basifying agents usually used in dyeing of keratin fibres or alternatively using standard buffer systems, present in compositions A, A' or in compositions C, C mixed with composition A, A' to give composition B, B', respectively.

Among the acidifying agents for the compositions used in the invention, examples that may be mentioned include mineral or organic acids, for instance hydrochloric acid, orthophosphoric acid or sulfuric acid, carboxylic acids, for instance acetic acid, tartaric acid, citric acid and lactic acid, and sulfonic acids; the acid is preferably an organic acid such as citric acid.

The alkaline agents are preferably chosen from aqueous ammonia, alkali metal carbonates or hydrogen carbonates, alkanolamines such as monoethanolamine, diethanolamine and triethanolamine, and also derivatives thereof, sodium hydroxide, potassium hydroxide and the compounds having the following formula:

in which formula W is a propylene residue optionally substituted with a hydroxyl group or a C1-C4 alkyl radical; R _a , Rb, R _c and R _d , which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl or C1-C4 hydroxyalkyl radical.

Process for preparing composition A and A '

Compositions A and A' may be obtained in the following manner: Ingredients a) to e), or a') to e') as defined are mixed together by hand or with a standard mixer and/or an extruder and/or are subjected to a standard mechanical stress pressure.

Dyeing process using the composition of the invention

According to a particular embodiment of the invention, the process for dyeing keratin fibres, in particular human keratin fibres such as the hair, involves the following steps:

- i) in a first stage, treating the keratin fibres with an aqueous composition B comprising: a) at least 10% by weight, relative to the weight of the said composition, of red henna powder; and

b) at least one oil, preferably of plant origin, and/or at least one butter, preferably of plant origin; and then

- ii) in a second stage, removing the composition from the keratin fibres, preferably by rinsing;

- iii) optionally applying a heat treatment to the keratin fibres, at a temperature above 60°C, preferably ranging from 60°C to 220°C, preferably with a hairdryer;

- and then treating the keratin fibres with an aqueous composition B' comprising:

a') at least 10% by weight, relative to the weight of the said composition, of powder of indigo-producing plant(s) and

b') optionally at least one oil, preferably of plant origin, and/or at least one butter, preferably of plant origin;

followed by repeating steps ii) and iii).

According to a first particular embodiment i) of the process of the invention, compositions B and B' contain, respectively, as ingredient b) and b'), one or more oils as defined previously.

According to another particular embodiment ii) of the process of the invention, composition B contains as ingredient b) one or more oils as defined previously and composition B' does not contain any oil or butter.

According to yet another particular variant iii) of the process of the invention, composition B contains as ingredient b) one or more oils as defined previously and composition B' contains as ingredient b') one or more butters as defined previously.

According to another particular embodiment iv) of the process of the invention, compositions B and B' contain, respectively, as ingredient b) and b'), one or more butters as defined previously.

According to another preferred variant v) of the process of the invention, composition B contains as ingredient b) one or more butters as defined previously and composition B' does not contain any oil or butter.

According to another particular variant vi) of the process of the invention, composition B contains as ingredient b) one or more butters as defined previously and composition B' contains as ingredient b') one or more oils as defined previously.

According to another advantageous variant of the process of the invention, composition B does not contain any ingredient b) and composition B' contains as ingredient b') one or more butters as defined previously and/or one or more oils as defined previously.

In a particularly preferred manner, the dyeing process is performed according to option ii) above.

According to a particularly advantageous embodiment of the invention, the dyeing process is performed in at least four successive steps:

- in the first step, composition B as defined previously is prepared preferably in the form of a "poultice" from composition A, which is preferably compact and/or anhydrous, and an aqueous composition C, preferably water;

- in the second step, the said composition B as defined previously is applied to the keratin fibres and is left on the said fibres preferably for a minimum time of 30 minutes, preferentially a time ranging from 30 minutes to 24 hours and better still ranging from 1 hour to 12 hours;

- in the third step, the keratin fibres are rinsed with water until composition B has disappeared from the said fibres, preferably without shampooing;

- optionally, the keratin fibres are then dried with a hairdryer or with a heating iron; and then

- in the fourth step, composition B' as defined previously is prepared preferably in the form of a "poultice" from composition A', which is preferably compact and/or anhydrous, and an aqueous composition C, preferably water;

- in the fifth step, the said composition B' as defined previously is applied to the keratin fibres and is left on the said fibres preferably for a minimum time of 30 minutes, preferentially a time ranging from 30 minutes to 24 hours and better still ranging from 1 hour to 12 hours; - in the sixth step, the keratin fibres are rinsed with water until composition B' has disappeared from the said fibres, preferably without shampooing;

- optionally, the keratin fibres are then dried with a hairdryer or with a heating iron;

it being understood that:

composition A comprises:

a) at least 10% by weight, relative to the weight of the said composition, of red henna powder as defined previously;

b) optionally at least one oil and/or butter as defined previously;

c) optionally at least one fatty substance other than the oil(s) or butters b); and

d) optionally at least one surfactant;

e) optionally at least one natural dye other than a) and a') as defined previously; and composition A' comprises:

a') at least 10% by weight, relative to the weight of the said composition, of powder of indigo- producing plant(s) as defined previously;

b') optionally at least one oil as defined previously; c') optionally at least one fatty substance other than the oil(s) or butters b);

d') optionally at least one surfactant as defined previously; and

e') optionally at least one natural dye other than a) and a') as defined previously;

it being understood that at least one of the two compositions B or B' comprises at least one oil and/or one butter b) or b').

According to a more particular embodiment of the invention, the dyeing process is performed in at least four successive steps:

- in the first step, composition B is prepared preferably in the form of a "poultice" as defined previously from composition A as defined previously;

- in the second step, composition B is applied to the keratin fibres and is left on the said fibres preferably for a minimum time of 30 minutes, preferentially a time ranging from 30 minutes to 24 hours and better still ranging from 1 hour to 12 hours;

- in the third step, the keratin fibres are rinsed with water until composition B has disappeared from the keratin fibres;

- the keratin fibres are then dried, preferably with a hairdryer; and then

- in the fourth step, composition B' is prepared preferably in the form of a "poultice" as defined previously from composition A' as defined previously;

- in the fifth step, composition B' is applied to the keratin fibres and is left on the said fibres preferably for a minimum time of 30 minutes, preferentially a time ranging from 30 minutes to 24 hours and better still ranging from 1 hour to 12 hours;

- in the sixth step, the keratin fibres are rinsed with water until composition B' has disappeared from the keratin fibres; and

- the keratin fibres are then dried, preferably with a hairdryer.

To prepare compositions B and B', preferably in the form of a poultice, in the first step, the aqueous compositions C and C are mixed with compositions A and A', respectively, as defined previously. Preferably, the mixing is performed with water used at a temperature ranging from 40°C to 98°C.

According to another embodiment of the invention, compositions A and A' are mixed with or broken down into aqueous compositions C and C, preferably water, at a temperature below 40°C, in particular between 10°C and 40°C.

Preferably, the ratio of the amount by weight of composition A and/or A' of the invention/amount by weight of aqueous composition C and/or C and preferably water ranges from 1/1 to 1/3 and is preferably 1/2.

Irrespective of the application method, the application temperature of composition B or B' to the keratin fibres ranges from room temperature (15 to 25°C) to 80°C and more particularly from 15 to 45°C. Thus, after application of composition B or B' according to the invention, the head of hair may advantageously be subjected to a heat treatment by heating to a temperature ranging from 30 to 60°C. In practice, this operation may be performed using a styling hood, a hairdryer, an infrared ray dispenser or other standard heating appliances. More particularly, the process of the invention is performed according to the following two processes:

- Process 1 :

A composition B preferably in the form of a poultice containing at least 10% of henna powder (1 part) as defined previously and water at a temperature of between 40 and 98°C (2-3 parts) is applied to the head, for a minimum of 30 minutes, preferably between 30 minutes and 24 hours and better still between 1 hour and 12 hours, followed by rinsing, preferably without shampooing, and the hair is then dried, followed by applying, after a time of between 1 hour and 1 week and preferably between 12 hours and 48 hours, such as after a time of 24 hours, a composition B' containing at least 10% by weight of powder of indigo- producing plant(s) (1 part) and water at a temperature of between 40 and 98°C (2-3 parts), for a minimum of 30 minutes, preferably between 30 minutes and 24 hours and better still between 1 hour and 12 hours, followed by rinsing, preferably without shampooing, and the hair is then dried.

- Process 2:

A composition B preferably in the form of a poultice containing at least 10% of henna powder (1 part) as defined previously and water at a temperature of between 10°C and 40°C (2-3 parts) is applied to the head, for a minimum of 30 minutes, preferably between 30 minutes and 24 hours and better still between 1 hour and 12 hours, followed by rinsing, preferably without shampooing, and the hair is then dried, followed by applying, after a time of between 1 hour and 1 week and preferably after a time of 24 hours, a composition B' preferably in the form of a poultice containing indigo (1 part) and water at a temperature of between 10°C and 40°C (2-3 parts), for a minimum of 30 minutes, preferably between 30 minutes and 24 hours and better still between 1 hour and 12 hours, followed by rinsing, preferably without shampooing, and the hair is then dried.

Preferably, after drying the hair, a heating iron at between 100 and 230°C and preferably between 130 and 180°C is then used along the length of the head of hair.

A particular form of the invention relates to a dyeing process which is performed at room temperature (25° C).

According to a particularly advantageous embodiment of the invention, all the ingredients used in the dyeing process are of natural origin, and preferably of plant origin.

The evaluation of the coloration can be done visually or read on a spectrocolorimeter (such as Minolta CM3600d, illuminant D65, angle 10°, SCI values) for the L ^* , a ^* , b ^* colorimetric measurements. In this L ^* , a ^* , b ^* system, L ^* represents the intensity of the color, a ^* indicates the green/red color axis and b ^* indicates the blue/yellow color axis. The lower the value of L, the darker or more intense the color. The higher the value of a ^* , the redder the shade; the higher the value of b ^* , the yellower the shade. The variation in coloring between the colored locks of natural white hair (NW) which is untreated (control) and after treatment or coloration are defined by ΔΕ ^* , corresponding to the colour uptake on keratin fibers, according to the following equation:

ΔΕ* = -(L ^* — L _o ^* ) ² +(a ^* — a _o ^* f + (b ^* - b ₀ ^* ) ²

In this equation, L ^* , a ^* and b ^* represent the values measured after dyeing the natural hair comprising 90% of white hairs and L ₀ ^* , a ₀ ^* and b ₀ ^* represent the values measured for the untreated natural hair comprising 90% of white hairs.

The greater the value of ΔΕ, the greater the difference in color between the control locks and the dyed locks and the greater colour uptake is.

On the other hand for evaluating the selectivity of the color between the root and tip of the keratin fiber, measurement can be done on permed or sensibilised white hair (PW) and natural white hair, wherein the variation in coloring between the colored locks PW and the colored natural white hair are defined by ΔΕ ^* , corresponding to the selectivity of the colour, is calculated according to the following equation: ΔΕ* = -(L ^* — L _o ^* ) ² +(a ^* — a _o ^* f + (b ^* - b ₀ ^* ) ²

In this equation, L ^* , a ^* and b ^* represent the values measured after dyeing the natural hair comprising 90% of white hairs and L ₀ ^* , a ₀ ^* and b ₀ ^* represent the values measured after dyeing the permed or sensibilised hair. The lowest ΔΕ ^* , the best homogeneity of the hair color.

If the light fastness is investigated, ΔΕ ^* is also calculated for the L ₀ ^* , a ₀ ^* , b ₀ ^* and L ^* , a ^* , b ^* measured of the locks before and after exposure to the light, respectively.

Chromaticity in the CIE L ^* , a ^* , b ^* colorimetric system is calculated according to the following equation :

The greater the value of C ^* , the greater the chromaticity is.

The examples that follow serve to illustrate the invention without, however, being limiting in nature. I) EXAMPLES OF DYEING

The percentages are indicated on a weight basis relative to 100 g of composition. Composition 1 :

1 part by weight of composition 1 is mixed with 3 parts by weight of hot water (at about 60°C) in a bowl.

The poultice obtained is applied to 90% grey hair, with a leave-on time of 30 minutes.

The hair is rinsed thoroughly until no more poultice remains visible to the eye.

The hair is dried with a hairdryer.

1 part by weight of composition 2 is mixed with 3 parts by weight of hot water (at about 60°C) in a bowl.

The poultice obtained is applied to the hair predyed with composition 1 , with a leave-on time of 30 minutes.

The hair is rinsed thoroughly until no more poultice remains visible to the eye.

The hair is dried with a hairdryer.

An aesthetic strong brown colour is obtained.