FR3104950A1 - Process for dyeing keratin fibers using a composition comprising monodisperse particles based on at least one nonionic polymer and a drying step using a forced air drying device - Google Patents

Abstract

The present invention relates to a process for dyeing keratin fibers comprising a step of applying to the keratin fibers a composition comprising monodisperse particles based on at least one nonionic polymer and a step of drying using 'a forced air drying device.

Description

Process for dyeing keratin fibers using a composition comprising monodisperse particles based on at least one non-ionic polymer and a drying step using a forced-air drying device

Technical field of the invention

The present invention relates to a process for dyeing keratin fibers comprising a step of applying to the keratin fibers a composition comprising monodisperse particles based on at least one non-ionic polymer and a step of drying using a forced-air drying device.

Background of the invention

It is known to be able to dye the hair with dye compositions containing oxidation dye precursors, called oxidation bases or oxidation couplers. Such a process is more commonly referred to as "oxidation staining". The oxidation bases are generally derivatives of para-phenylenediamines, para-aminophenol, or certain heterocycles such as dihydropyrazolones or pyrazoles. The couplers are generally aromatic derivatives substituted by auxochrome functions in the meta position of each other, such as meta-phenylenediamines, meta-aminophenols, ortho-aminophenols, or even five- or six-membered heterocycles such as diaminopyridine derivatives, aminopyrazoles, or alternatively bicyclic heterocycles such as indole, indazole, quinoline, benzimidazole, benzoxazole and other derivatives. Each of the compounds, bases or couplers, are colorless. When they are mixed in the presence of an oxidant, such as hydrogen peroxide for example, an oxidative coupling reaction occurs and leads to the formation of colored compounds.

These dyes are therefore of varied colors, depending on the base/coupler pairs involved. Thus, a wide range of color shades can be obtained on the hair by the variety of mixtures of base/coupler pairs. These colors and their shades are qualified by those skilled in the art as so-called fundamental colors with regard to the natural colors of hair, i.e. black, dark brown, light brown, etc. They are said to be chromatic when warm or cold shades , such as purple, red, blue, russet, etc., are obtained.

This hair dyeing process offers known advantages, such as good resistance to shampoo, and to external attacks such as friction, for example, over several weeks. It also allows you to dye all the hair evenly from root to tip.

However, this dyeing process has certain drawbacks.

Indeed, this coloring process is not reversible. That is to say, once the dyes have formed within the keratin fibre, there is no dye extraction process that would make it possible to find the initial color state of the hair fibre. In addition, the process of formation of oxidation coloring being oxidative, the use of an oxidant under the conditions of use can lead to a degradation of the fiber and modify the natural melanin of the hair. In other words, the natural color of the hair before dyeing is degraded and cannot be immediately regained.

In addition, oxidation coloring is based on the formation of dyes in situ of the hair which absorb all or part of the visible light, thus conferring in certain sought-after cases colors such as red, copper, red, purple, etc…. However, when the dye is performed on dark hair (black, dark brown, etc.) which themselves absorb a large part of the visible light, it is very difficult to perceive the chromatic nuances. This phenomenon is explained by the fact that the keratinous substrate already absorbing light by the presence of endogenous polymeric dyes such as melanin, eumelanin or pheomelanin, the additional dyes introduced by oxidative condensation can only absorb the residual light not absorbed by the substrate. Thus, shades on dark hair are generally less visible and less chromatic.

Furthermore, the duration of application of an oxidation dye composition which is generally at least 30 minutes and its application by comb also represent a drawback.

An additional disadvantage is that when mixing bases and oxidation couplers in the preparation container before application to hair, an intense, dark, brown-black color develops. The appearance may cause concern for the person to whom the composition is applied.

In addition, the use of an oxidizing agent in the oxidation dye composition can lead, after several applications over time, to a degradation of the intrinsic quality of the keratin fiber, the weakened hair possibly becoming brittle and dull.

It is also known to be able to dye the hair using cosmetic compositions comprising direct dyes or colored pigments. This is called direct coloring. Direct coloring has certain drawbacks such as, for example, the possible staining of the skin of the scalp or the hands in the event of non-wearing of protective gloves, or else the low resistance to shampoo. In addition, as with oxidation coloring, when the keratin fibers are dyed with a direct dye or a colored pigment, it is not possible to quickly regain the original natural color of the hair. Finally, it is known that direct dyes or pigments, due to their polyaromatic molecular structure, can be sensitive to UV radiation and degrade.

Moreover, it is common that over time the natural color, originally due to the formation of endogenous melanin granules (melanosomes) within the keratin fiber of the hair, fades, becomes lighter and tends towards a white color, sometimes yellowed. The yellow component of the color is undesirable and therefore particularly unattractive. It is desired to be able to have an aesthetic white hair color that corresponds to what seniors desire.

Oxidation coloring products have thus been proposed aimed at bleaching yellowed white hair. However, this type of hair is known to be fragile. Thus, the conditions of application of oxidation coloring products, in particular the high application pH, can lead to additional degradation of the hair fiber.

Other solutions based on the use of direct dyes are also proposed. However, these solutions are also unsatisfactory because the color can remain sensitive to natural UV radiation and change over time and thus lead to an unsightly color. In addition, the direct coloring compositions can stain the scalp as explained above.

There is therefore a need for chromatic and reversible hair coloring.

Patent application WO 2006/136725 describes cosmetic compositions comprising monodisperse particles capable of producing a periodic ordered network when they are applied to keratin materials, in particular the skin. Such a network can impart color to the substrate to which it is applied. Such a network is still sometimes called "colloidal crystal" or "photonic crystal". The color generation mechanism is based in this case on that of Bragg diffraction, which makes it possible to reflect a selective range of wavelengths, for example blue, violet, green, etc. It is also known that such ordered arrangements of particles confer a goniochromatic color, that is to say whose color varies according to the angle under which the light falls on the ordered network of particles. More precisely, the cosmetic film formed after deposition of the cosmetic composition on the substrate contains superposed planes each consisting of a network of particles ordered on the plane. This configuration is at the origin of the variation of the perceived color according to the angle under which the substrate is observed. This color variation therefore does not meet the need to provide a homogeneous and invariant color regardless of the conditions under which the substrate is seen. In addition, the intensity of the color obtained by application of these compositions is low and the colors obtained are not very chromatic.

Application US 2009/0047352 describes a method for dyeing fibers such as hair consisting in bringing the fibers into contact with a composition comprising monodisperse particles capable of forming a colloidal crystal which diffracts light in the visible range. This method consists of vertical soaking in a bath containing the particles in dispersion, followed by drying at room temperature overnight to allow the formation of the colloidal crystal. This method is therefore totally inappropriate for an application in hair coloring, whether in a hairdressing salon or at home. In addition, as explained above, colloidal crystals are known to impart color variation depending on the angle at which light hits them. This phenomenon, called goniochromatism, does not make it possible to obtain a homogeneous aesthetic color whatever the viewing angle, which represents a disadvantage.

In addition, the use of colloidal crystals does not meet the need for yellowing white hair. Indeed, the use of preformed colloidal crystals or their formation over a disproportionate period of time does not confer any color correction, their reflection intensity being too low on a colored substrate such as a yellowed white.

Thus, there is a real need to develop a process for coloring keratinous fibers making it possible to obtain a visible, intense and chromatic coloring and whose color does not vary according to the angle of observation on natural hair or not and which can be reversed by simply washing with water, which restores the original color of the hair. There is also a need to develop a process for dyeing keratin fibers that is more respectful of the structure of the hair, whether at the level of the cuticle, of the cortex or of the internal parts of the keratin fiber. Such a process should also be quick and simple, for example by avoiding the use of an application comb. The compositions used in such a process should also not have a dark colored appearance. Finally, such a process should be capable of removing yellow from yellowed white hair

The applicant has surprisingly discovered that at least some, if not all of these problems can be solved by the method according to the present invention.

According to a first aspect, the subject of the present invention is a process for dyeing keratin fibers comprising the following successive steps:
i) application to the keratin fibers of a composition comprising monodisperse particles having an average size ranging from 200 nm to 0.8 μm using a spray device; And
ii) drying the keratin fibers using a forced-air dryer;
wherein the monodisperse particles are particles based on at least one nonionic polymer.

According to a second aspect, the subject of the present invention is the use of a composition comprising monodisperse particles having an average size ranging from 200 nm to 0.8 μm and of a forced air drying device for the deyellowing of the hair yellowed whites.

Detailed description of the invention

By "keratin fibers" is meant fibers of human or animal origin such as hair, body hair, eyelashes, eyebrows, wool, angora, cashmere or fur. According to the present invention, the keratin fibers are preferably human keratin fibers, more preferably the hair.

By "successive steps", we mean steps implemented in the order indicated.

By "average size" of the particles is meant the number-average diameter of the particles.

By "monodisperse particles" is meant particles whose average size has a coefficient of variation CV less than or equal to 10%, preferably less than or equal to 7%, more preferably less than or equal to 5%, even more preferably less than or equal to 3%.

The coefficient of variation CV is defined by the relation CV=s/D, s being the standard deviation of the size distribution of the particles and D the average size of the latter.

The average size D and the standard deviation s can be measured on 40 to 300 particles such as 50 or 250 particles by analyzing an image obtained using a scanning electron microscope, for example that of reference S -3400N from the HITACHI company. Image analysis software can be used to facilitate this measurement, for example the Winroof® software, marketed by the company Mitani Corporation.

By "non-ionic polymer" is meant a polymer not comprising any ionic or ionizable group.

The term "bath ratio" means the ratio between the total weight of the composition applied to the keratin fibers and the total weight of keratin fibers to be treated.

By "alkyl group" is meant a hydrocarbon radical, linear or branched, saturated.

By "(C _x -C _y ) alkyl group" is meant an alkyl group comprising from x to y carbon atoms.

By "aryl group" is meant a mono or polycyclic carbon group, condensed or not, comprising from 6 to 22 carbon atoms, and of which at least one ring is aromatic. Preferably the aryl group is phenyl.

By "dark keratin fibers" is meant keratin fibers which have a luminescence L*, calculated in the C.I.E.L*a*b* system, of less than or equal to 45 and preferably less than or equal to 40, knowing moreover that L*= 0 equals black and L*=100 equals white.

By "film-forming polymer" is meant a polymer capable of forming, on its own or in the presence of an auxiliary film-forming agent, a macroscopically continuous film on a support, in particular on keratin fibres, and preferably a cohesive film.

By "hydrophobic polymer" is meant a polymer having a solubility in water at 25° C. of less than 1% by weight.

By "yellowed white hair", we mean white hair whose white appearance has yellow undertones.

The terms "at least one" and "one or more" are synonymous and may be used interchangeably.

Coloring process

According to a first aspect, the subject of the present invention is a process for dyeing keratin fibers as defined above.

Step ii) of the method according to the present invention is implemented after step i).

When the composition comprising the monodisperse particles is applied by spraying to the keratin fibres, an amorphous material is formed in situ on the cuticle, consisting of a random arrangement of monodisperse particles locally compacted in an orderly manner. This new material confers an intense and chromatic color, in particular on dark keratin fibers and which does not vary according to the angle of observation, and makes it possible in particular to de-yellow yellowed white hair. The color generated in situ is reversible by simply washing with water, which restores the original color of the hair. In addition, the overall quality of the hair and in particular of its cuticle is preserved.

Surprisingly, this process works whereas a conventional process of soaking in a bath containing a dispersion of monodisperse particles for variable times between 5 and 45 minutes, followed by drying with a hair dryer does not produce any color.

The successive steps i) and ii) of the process can be repeated several times. In this case, the compositions used during step i) and in particular the size of the monodisperse particles included in these compositions may be identical or different.

Composition

The composition used in the process according to the invention comprises monodisperse particles. The process according to the invention is particularly advantageous in that the composition is white during application and therefore does not have a dark colored appearance.

Monodisperse particles

The monodisperse particles have an average size ranging from 200 nm to 0.8 µm. Preferably, the monodisperse particles have an average size ranging from 200 nm to 0.6 μm. More preferentially, the monodisperse particles have an average size ranging from 200 nm to 500 nm.

Preferably, the monodisperse particles are spherical.

Preferably, the monodisperse particles have a refractive index n _p ranging from 1.40 to 1.80.

All the monodisperse particles corresponding to the same average size can have substantially the same refractive index.

The refractive index of monodisperse particles is defined as being the average refractive index calculated according to the volume average of the constituents.

Monodisperse particles are particles based on at least one non-ionic polymer.

Non-ionic polymer

The non-ionic polymer can be chosen from polystyrene, polymers of (C ₁ -C ₈ )alkyl-styrene, poly(meth)acrylates of (C ₁ -C ₈ )alkyl optionally substituted by a hydroxy group, poly Aryl (meth)acrylates, styrene/(C ₁ -C ₄ )alkyl (meth)acrylate copolymers, polylactic acids optionally substituted on the carbon in position 3 of the propionate unit by a (C ₁ -C ₆ ) group alkyl optionally substituted by one or two hydroxy radicals, polyglycolic acids, poly(lactic-co-glycolic) acids, polycaprolactones, and mixtures thereof.

Preferably, the nonionic polymer is chosen from poly(C ₁ -C ₈ )alkyl methacrylates. More preferably, the nonionic polymer is chosen from poly(C ₁ -C ₄ )alkyl methacrylates and mixtures thereof. Even more preferentially, the non-ionic polymer is chosen from polymethyl methacrylates, polyethyl methacrylates, polyn-butyl methacrylates, polyisobutyl methacrylates, polyt-butyl methacrylates, poly2-hydroxyethyl methacrylates, 2-hydroxypropyl polymethacrylates and mixtures thereof.

Most preferably, the nonionic polymer is chosen from polymethyl methacrylates.

The glass transition temperature T _g of the nonionic polymer can be greater than or equal to 45°C. Preferably, the glass transition temperature T _g of the nonionic polymer can be greater than or equal to 55°C. More preferably, the glass transition temperature T _g of the nonionic polymer can be greater than or equal to 80°C.

Preferably, the composition comprising the monodisperse particles is in the form of an aqueous colloidal suspension. The aqueous colloidal suspension may comprise water or a mixture of water and one or more water-miscible solvents, preferably water.

The monodisperse particles can possess a positive or negative surface charge, preferably negative.

Monodisperse particles can be composite. In this case, these can for example comprise a core and a shell made of different materials. The materials of the core or the shell of the particles can for example be chosen in order to increase their refractive index.

Preferably, the composition comprising the monodisperse particles comprises a total content of monodisperse particles ranging from 0.5% to 20%, preferably from 1% to 10%, more preferably from 5% to 10% by weight relative to the total weight of composition.

The composition comprising the monodisperse particles can be applied to the keratin fibers during step i) in a bath ratio ranging from 0.1 to 10, preferably from 5 to 10.

The composition comprising the monodisperse particles can have a pH ranging from 7.5 to 11, preferably from 7.5 to 9.

The composition comprising the monodisperse particles may also comprise at least one usual cosmetic ingredient different from the compounds described above, chosen in particular from nonionic, anionic, cationic and amphoteric surfactants, fillers, pearlescent agents, opacifying agents , sequestering agents, film-forming polymers, cationic, anionic or neutral polymers, associative polymers, plasticizers, silicones, thickening agents, oils, anti-foaming agents, moisturizing agents, emollients, penetrants, fragrances and preservatives.

Depending on their nature and the destination of the composition, the usual cosmetic ingredients may be present in usual quantities, easily determined by those skilled in the art, and which may be comprised, for each ingredient, between 0.01 and 80% by weight. . A person skilled in the art will take care to choose the ingredients entering into the composition, as well as their quantities, so that they do not harm the properties of the composition.

Keratin fibers

Preferably, the method according to the invention is implemented on dark keratin fibres.

The dark keratinous fibers can be naturally or artificially dark hair, preferably naturally dark hair.

By "naturally or artificially dark hair" is meant hair whose tone height is less than or equal to 6 (dark blonde) and preferably less than or equal to 4 (chestnut). Artificially colored hair is hair whose color has been modified by a coloring treatment, for example coloring with direct dyes or oxidation dyes.

By "height of tone" we mean the unit known to hairdressing professionals, and published in the work "Science of hair treatments" by Charles ZVIAK 1988, Ed. Masson, p. 215 and 278, the pitches range from 1 (black) to 10 (light light blond), one unit corresponding to one tone, the higher the number, the lighter the shade.

Alternatively, the method according to the invention can be implemented on yellowed white hair.

Step ii) of drying the keratin fibers

Step ii) of drying the keratin fibers is carried out using a forced-air drying device.

Preferably, the pulsed-air drying device is chosen from heated helmets and hair dryers. More preferably, the forced-air drying device is a hair dryer.

Preferably, the forced air drying device is maintained at a temperature ranging from 30°C to 120°C, preferably from 45°C to 80°C, more preferably from 45°C to 60°C.

Preferably, step ii) of drying the keratin fibers is implemented less than 5 min after step i). More preferably, step ii) of drying the keratin fibers is implemented directly after step i).

Preferably, the duration of step ii) of drying the keratin fibers is less than 10 min. More preferably, the duration of step ii) of drying the keratin fibers is less than 5 min.

Additional step iii)

The method according to the invention may also comprise a step iii) of application to the keratin fibers of a composition comprising at least one hydrophobic film-forming polymer.

Step iii) is implemented after step ii).

The application of a hydrophobic film-forming polymer makes it possible in particular to improve the water resistance of the coloring obtained by the coloring process according to the present invention.

Such a composition is preferably in the form of a dispersion of the hydrophobic film-forming polymer in a non-aqueous solvent, more preferably in ethanol.

Preferably, this composition is applied using a spray device.

As an example of a hydrophobic film-forming polymer that can be used, mention may be made of the particles of at least one polymer surface-stabilized by a stabilizing agent, the polymer of the particles being a polymer of C ₁ alkyl (meth)acrylate -C ₄ and the stabilizing agent being an isobornyl (meth)acrylate polymer selected from isobornyl (meth)acrylate homopolymer and random copolymers of isobornyl (meth)acrylate and (meth)acrylate C ₁ -C ₄ alkyl. These particles are described in particular in patent application FR 3014875.

Spray device

The spray device can for example be a pump bottle or an aerosol container, preferably a pump bottle.

Use

According to a second aspect, the subject of the present invention is the use of a composition as described above combined with a forced air drying device as described above for the removal of yellowed white hair.

The composition is preferably applied using a spray device as described above.

The following examples serve to illustrate the invention without, however, being of a limiting nature.

Examples

Example 1: Preparation of a suspension of monodisperse particles of polymethyl methacrylate (PMMA) having an average size of 248nm and a coefficient of variation (CV) of 5.14%

The monodisperse particles were prepared according to the procedure described below. The specificities of the raw materials used in the context of this synthesis are indicated in the table below.

Raw materials Number of moles Quantity Methyl methacrylate distributed by Accros organics under reference 10569000 (99.9%) 0.837 83.8g 2,2'-azobis(2-methylpropionamide) dichloride; 1.6.10 ^-3 0.44g Water 500ml Water for catalyst solution 20ml

Procedure:

Methyl methacrylate then water are introduced into a 1L reactor fitted with an anchor stirrer and the whole is stirred at 300 rpm while passing a stream of nitrogen for 30 min. This reaction medium is heated so as to reach a stable temperature at 78° C., then the catalyst, 2,2'-azobis(2-methylpropionamide) dichloride, is introduced in solution in water. The exothermicity of the reaction causes the temperature of the solution to rise to 90° C. The whole is kept under stirring for 6 h at 90° C., then the temperature is allowed to drop to ambient temperature. The reaction medium is kept at rest for 12 h. The suspension white water thus obtained is collected using a closed filter fitted with a filter plate to eliminate large aggregates.The size of the particles is characterized by SEM analysis (SEM-FEG microscope, device sold under the reference S-3400N by HITACHI Company). mean particle size is 248nm with 5.14% standard deviation (count on 50 particles).

Example 2: Preparation of a suspension of monodisperse particles of polymethyl methacrylate (PMMA) having an average size of 298nm and a coefficient of variation (CV) of 4.99%

The monodisperse particles were prepared according to the procedure described below. The specificities of the raw materials used in the context of this synthesis are indicated in the table below.

Raw materials Number of moles Quantities Methyl methacrylate distributed by Acros organics under reference A0322631 (99.9%) 2.66 266.7g 2,2'-azobis(2-methylpropionamide) dichloride 5.20.10-3 1.41g Water 800ml Water for catalyst solution 20ml

Procedure:

Methyl methacrylate then water are introduced into a 1L reactor equipped with an anchor stirrer and the whole is stirred at 300 rpm while passing a stream of argon for 15 min. This reaction medium is heated so as to reach a stable temperature at 75° C., then the catalyst, 2,2'-azobis(2-methylpropionamide) dichloride, is introduced in solution in water. The whole is kept under stirring for 6 h at 78° C., then the temperature is allowed to drop to ambient temperature. The reaction medium is kept at rest for 12 h. The white suspension thus obtained is collected using a closed filter equipped with a filter plate to eliminate large aggregates.The size of the particles is characterized by SEM analysis (SEM-FEG microscope, device sold under the reference S-3400N by the company HITACHI). mean particle size is 298nm with 4.99% standard deviation (count on 50 particles).

Example 3: Preparation of a suspension of monodisperse particles of polymethyl methacrylate (PMMA) having an average size of 340nm and a coefficient of variation (CV) of 3.66%

The monodisperse particles were prepared according to the procedure described below. The specificities of the raw materials used in the context of this synthesis are indicated in the table below.

Raw materials Number of moles Quantity Methyl methacrylate distributed by Accros organics under reference 10569000 (99.9%) 1,618 162g 2,2'-azobis(2-methylpropionamide) dichloride 2.76.10 ^-3 0.75g Water 800ml Water for catalyst solution 20ml

Procedure:

Methyl methacrylate then water are introduced into a 1L reactor equipped with an anchor stirrer and the whole is stirred at 260 rpm while passing a stream of argon for 15 min. This reaction medium is heated so as to reach a stable temperature at 75° C. then the catalyst, 2,2'-azobis(2-methylpropionamide) dichloride, is introduced in solution in water. The whole is kept under stirring. for 6 h at 62° C., then the temperature is allowed to drop to room temperature. The reaction medium is kept at rest for 6 h. The white suspension thus obtained is collected using a closed filter fitted with a filter plate to eliminate large aggregates.The size of the particles is characterized by SEM analysis (SEM-FEG microscope, device sold under the reference S-3400N by the company HITACHI).The average size is 340 nm with 3.66% standard deviation ( counting on 50 particles).

Example 4: Dark Hair Color Study

Each of the compositions indicated in the table below were prepared and tested according to the procedure described below:

Composition
Average particle size (nm) Coefficient of variation (CV) Particle concentration (% mass) Membership 1
(Prepared from Example 1) 248 5.14% 10% Membership 2
(Prepared from Example 2) 298 4.99% 10% Membership 3
(Prepared from Example 3) 340 3.66% 10%

Procedure:

Each of the above compositions are applied to strands of hair of Asian type and tone height HT4 (1g; 20 cm in length) using a spray device, in the form of 3 sprays "duplex " in about 10 sec.
The locks are then dried with a hair dryer for about 1 min, while combing them. Spectrophotometric measurements of L*a*b* values are then carried out according to the procedure described below.

Spectrophotometric measurements:

The color of the locks is evaluated by colorimetry in the CIE L*a*b* system using a Konica Minolta model CM3610D spectrocolorimeter (illuminant D65, angle 10°, specular component included).
In this L*a*b* system; L* represents the lightness of the color, a* indicates the green/red color axis and b* the blue/yellow color axis. The lower the value of L*, the darker and more powerful the coloration.
The lower the value of a* and the greener the color, the higher the value of a* the more red the color.
The lower the value of b* and the more blue the color, the higher the value of b* the more yellow the color.

The rise in color corresponds to the variation in color between the locks of hair, before and after coloring are defined by (ΔE*) according to the following equation:


In this equation, L*, a* and b* represent the values measured on locks of hair after coloring, and L ₀ *, a ₀ * and b ₀ * represent the values measured on locks of hair before coloring. The higher the value of ΔE*, the better the increase in color.

Results:

A lock color as described in the table below was obtained for each of the compositions tested:

Composition Color of the locks obtained Membership 1 Purple Membership 2 Blue Membership 3 Green

The results of the spectrophotometric measurements are shown in the table below:

I To b ΔL ΔE* HT4 natural hair before coloring 18.56 2.55 2.88 - - Membership 1 26.44 7.35 -9.09 7.88 15.11 Membership 2 29 -5.41 -3.66 10.44 14.67 Membership 3 28.27 -8.82 8.53 9.71 15.98

The results show that the process according to the present invention makes it possible to obtain an intense and chromatic color on dark hair. In addition, the color does not vary depending on the viewing angle.

SEM observations have allowed us to confirm that an amorphous material consisting of a random arrangement of locally compacted monodisperse particles in an orderly fashion forms in situ on the cuticle.

Example 5: Reversibility of the coloring process by washing with water or shampoo

The locks of hair treated with the compositions of example 4 were washed with water or with shampoo. Spectrophotometric measurements were carried out according to the procedure described in Example 4 after washing with water and after washing with shampoo. The ΔE* values are calculated relative to a lock of natural hair before coloring.

The results of the spectrophotometric measurements are shown in the table below:

I To b ΔL ΔE ^* HT4 natural hair 18.56 2.55 2.88 - - Membership 1 26.44 7.35 -9.09 7.88 15.11 Composition 1 after water wash 19.24 3.23 2.84 0.68 0.96 Composition 1 after shampoo 18.89 2.11 2.26 0.33 0.83 Membership 2 29 -5.41 -3.66 10.44 14.67 Composition 2 after water wash 20.47 1.3 -0.6 1.91 4.16 Composition 2 after shampoo 19.08 2.03 2.16 0.52 1.03 Membership 3 28.27 -8.82 8.53 9.71 15.98 Composition 3 after water wash 20.27 3.18 1.21 1.71 2.47 Composition 3 after shampoo 19.43 2.58 2.57 0.87 0.92

It is observed that the values of ΔE* after washing with water or with shampoo of the locks treated with each of compositions 1, 2 or 3 are very low. The coloring process is reversible by washing with water or shampoo.

Example 6: Coloring study on natural white hair 90% (BN 90%)

Composition 4 indicated in the table below was prepared and tested according to the procedure described below:

Composition
Average particle size (nm) Coefficient of variation (CV) Particle concentration (% mass) Composition 4
(Prepared from Example 2) 298 4.99% 20%

Procedure:

Composition 4 above is applied to a lock of hair of natural white type 90% (BN 90%) of 1g and 20 cm in length using a spray device, in the form of 3 sprays " duplex" in about 10 sec.

The lock is then dried with a hair dryer for about 1 min, while combing it.

Spectrophotometric measurements of L*a*b* values are then carried out according to the procedure described in example 4. The ΔE* values are calculated with respect to the lock of hair of 90% natural white type before coloring.

The results of the spectrophotometric measurements are shown in the table below:

I To b Δa Δb ΔL ΔE ^* 90% natural white type hair 57.81 0.74 14.41 0.00 Layout 4 72.51 -1.98 9.42 -2.72 -4.99 14.70 15.76

90% natural white type hair is characterized by a high b value and an a value close to zero. A yellow color therefore predominates. After application of composition 4, a significant decrease in the value of b (-4.99) and an increase in that of L (+14.70) are observed. This corresponds to a perception of disyellowing of the color of the hair. Thus, the method according to the present invention makes it possible to de-yellow the hair.

Example 7: Study of the remanence of the coloring of hair treated with a method according to the invention followed by the deposition of a hydrophobic film-forming polymer

Composition 5 indicated in the table below was prepared and tested according to the procedure described below:

Composition
Average particle size (nm) Coefficient of variation (CV) Particle concentration (% mass) Membership 5
(Prepared from Example 1) 248 5.14% 5%

Procedure:

The above composition 5 is applied to strands of hair of Asian type and HT4 tone height (1g; 20 cm in length) using a spray device, in the form of 3 sprays "duplex " in about 10 sec. The locks are then dried with a hair dryer for about 1 min, while combing them. After this first step, an ethanolic dispersion at 1% by weight of the polymer of example 4 (called P1 hereafter) of patent application FR 3014875, obtained beforehand in the dry state by a conventional spray-drying process with the BUCHI B290 equipment, is applied by aerosol to the hair dyed in the first step. The locks thus treated are then washed with water or shampoo.

Spectrophotometric measurements of L*a*b* values are then carried out according to the procedure described in example 4. The ΔE* values are calculated with respect to natural hair HT4.

The results of the spectrophotometric measurements are shown in the table below:

Entrance I To b ΔL ΔE ^* 1 HT4 natural hair 17.71 1.11 1.08 - - 2 Membership 5 26.44 7.35 -9.09 8.73 14.78 3 Composition 5, after spraying with a 1% mass dispersion of polymer P1 26.13 6.10 -8.84 8.42 13.94 4 Composition 5, after spraying with a 1% mass dispersion of polymer P1 and washing with water 25.65 5.76 -8.28 7.94 13.13 5 Composition 5, after spraying with a 1% mass dispersion of polymer P1 after shampooing 18.76 1.43 0.28 1.05 1.36

By comparing the results of entries 2 and 3, it can be seen that the application of the mass dispersion of the polymer P1 causes little variation in the color of the wick.

Comparing the results of entries 3 and 4, it can be seen that the color of the hair after rinsing with water practically does not vary. The application of the ethanolic dispersion comprising the hydrophobic film-forming polymer therefore helps to improve the water resistance of the coloring obtained by the coloring process according to the present invention.

On the other hand, after washing with shampoo, we find that the original color of the hair is found.

Claims (17)

Process for dyeing keratin fibers comprising the following successive steps:
i) application to the keratin fibers of a composition comprising monodisperse particles having an average size ranging from 200 nm to 0.8 μm, using a spray device; And
ii) drying the keratin fibers using a forced-air dryer;
wherein the monodisperse particles are particles based on at least one nonionic polymer. Process according to the preceding claim, in which the monodisperse particles have an average size ranging from 200 nm to 0.6 µm, preferably from 200 nm to 500 nm. A method according to any preceding claim, wherein the monodisperse particles are spherical. A method according to any preceding claim, wherein the monodisperse particles have a refractive index n _p ranging from 1.40 to 1.80. Process according to any one of the preceding claims, in which the composition comprises a total content of monodisperse particles ranging from 0.5% to 20%, preferably from 1% to 10%, more preferably from 5% to 10% by weight relative to the total weight of the composition. Process according to any one of the preceding claims, in which during stage i), the composition is applied to the keratin fibers in a liquor ratio ranging from 0.1 to 10, preferably from 5 to 10. Process according to any one of the preceding claims, in which the non-ionic polymer is chosen from polystyrene, polymers of (C ₁ -C ₈ )alkyl-styrene, poly(meth)acrylates of (C ₁ -C ₈ )alkyl optionally substituted by a hydroxy group, poly(meth)acrylates of aryl, styrene/(meth)acrylate (C ₁ -C ₄ )alkyl copolymers, polylactic acids optionally substituted on the carbon in position 3 of the unit propionate with a (C ₁ -C ₆ )alkyl group optionally substituted with one or two hydroxy radicals, polyglycolic acids, poly(lactic-co-glycolic) acids, polycaprolactones, and mixtures thereof. Process according to any one of the preceding claims, in which the nonionic polymer is chosen from poly(C ₁ -C ₈ )alkyl methacrylates, preferably from poly(C ₁ -C ₄ )alkyl methacrylates and mixtures thereof, more preferentially from polymethyl methacrylates, polyethyl methacrylates, poly-n-butyl methacrylates, poly-isobutyl methacrylates, poly-t-butyl methacrylates, poly-2-hydroxyethyl methacrylates, poly-2-hydroxypropyl methacrylates and mixtures thereof , even more preferably from polymethyl methacrylates. Process according to any one of the preceding claims, in which the glass transition temperature T _g of the non-ionic polymer is greater than or equal to 45°C, preferably greater than or equal to 55°C, more preferably greater than or equal to 80 °C. A method according to any preceding claim, wherein the keratin fibers are dark keratin fibers. Process according to any one of the preceding claims, in which step ii) is carried out less than 5 min after step i), preferably directly after step i). Process according to any one of the preceding claims, in which the duration of step ii) is less than 10 min, preferably less than 5 min. Method according to any one of the preceding claims, in which the forced-air drying device is chosen from heating caps and hair dryers, preferably a hair dryer. Process according to any one of the preceding claims, in which the forced air drying device is maintained at a temperature ranging from 30°C to 120°C, preferably from 45°C to 80°C, more preferably from 45°C C to 60°C. Process according to any one of the preceding claims, in which the process further comprises a step iii) of application to the keratin fibers of a composition comprising at least one hydrophobic film-forming polymer. Use of a composition as defined in any one of Claims 1 to 9 combined with a forced-air drying device as defined in any one of Claims 1, 13 or 14 for the removal of yellowed white hair. Use according to the preceding claim, in which the composition is applied to the hair using a spray device.