WO2000075240A1 - Interferential pigment and cosmetic composition containing said pigment - Google Patents

Abstract

An interferential pigment having a multilayer structure. Said structure has a spectral reflectance (RA; RB) which is close to a reference spectral reflectance (Rf; Rc) corresponding to a predetermined skin type or type of material, i.e. keratin fibres, for at least part of the visible spectrum.

Description

 Interference pigment and cosmetic composition comprising such a pigment. The present invention relates to an interference pigment having a multilayer structure and a composition, in particular a cosmetic composition, comprising such a pigment.

Many cosmetic compositions are colored using a mixture of pigments, the proportion of each pigment within the mixture being chosen as a function of the shade of color to be obtained.

Certain pigments must be used in conjunction with dispersing or stabilizing agents.

In this case, the cosmetic and / or dermatological active ingredients present in the composition must be compatible with these dispersing or stabilizing agents.

As a result, the formulation of the composition is relatively long and costly to develop in order to ensure compatibility between the cosmetic and / or dermatological active agents and the pigments for a whole range of shades.

Finally, the known pigments making it possible to make the compositions sufficiently covering to mask skin defects such as wrinkles, fine lines, blotches, also give them a rather unnatural appearance.

There is therefore a need to have a composition which makes it possible to mask in a more natural way the imperfections of the skin or of the keratin fibers

(hair, eyelashes, eyebrows) of human beings, whose presence on the user is relatively difficult to detect, even at the level for example of the border between the made-up and non-made-up areas.

We also know, in particular by the publication J. Soc. Cosmet. Chem.,

Jpn. Flight. 29, n ° 4, pp 353-371 (1996) cosmetic compositions incorporating a pigment constituted by elementary particles of mica coated with titanium oxide, capable of intensely reflecting the light coming from the front and of absorbing the light coming from side, creating shadow effects making the face appear thinner.

Such compositions do not provide as natural a result as is desirable when the purpose of makeup is to conceal slight skin imperfections.

The subject of the invention is a new interference pigment making it possible to obtain new effects and in particular to recreate the color of the skin or of materials, in particular fibers, keratinous for covering and masking defects.

This pigment is characterized by the fact that the multilayer structure has a spectral reflectance close to a reference spectral reflectance corresponding to a skin or material type, in particular of fibers, keratin predetermined, for at least part of the visible spectrum.

The type of skin concerned can be the Caucasian, mixed race, black or Asian type for example.

The type of keratin fibers can be blond, brown or red for example.

The pigment according to the invention makes it possible to recreate the color of the skin or of keratin materials such as the fibers, and to obtain a natural covering effect making it possible to camouflage or to conceal defects such as the veins, rosacea, spots, blackheads, fine lines and wrinkles or even white hair.

The pigment according to the invention can thus be used in a cosmetic composition or for the manufacture of a physiologically acceptable composition for concealing imperfections in the skin and keratin fibers. The pigment according to the invention can also be used to camouflage nail defects, such as in particular white spots.

In a particular implementation of the invention, the multilayer structure has a spectral reflectance close to a reference spectral reflectance corresponding to a predetermined skin type, for the entire visible spectrum.

Preferably, the spectral reflectance of the multilayer structure deviates, for the part of the visible spectrum considered, by at most +/- 10% from the reference spectral reflectance.

The multilayer structure of the pigment can be produced so as to have a spectral reflectance close to that of the skin type of the subject to which the composition is intended to be applied, for at least part of the visible spectrum, or even the entire visible spectrum.

It is thus possible to mask the imperfections of the skin while making the presence of the composition difficult to detect, even at the border between make-up and non-make-up areas, since the spectral reflectance corresponds substantially to that of the subject's skin. The reference spectral reflectance can have, for at least certain wavelength values, a reflectance chosen to attenuate a chromatic dominant of the type of skin considered, for example yellow. Advantageously, the multilayer structure is arranged so as to be substantially non-goniochromatic for incidences less than 45 °.

Advantageously, the multilayer structure is arranged to present a clarity parameter L * which is substantially constant for incidences less than 45 °. The multilayer structure can be symmetrical and include an odd number of layers.

Advantageously, the form factor (ratio between the largest longitudinal dimension and the largest transverse dimension) of the pigment is between 1 and 10. Preferably, the largest dimension of the pigment is between 10 and

50 μm.

Thanks to the size of less than 50 μm, the pigment is not a source of discomfort at the time of application and during use.

The size greater than 10 μm makes it possible to prevent the pigment from diffracting or diffusing excessively light and tends to facilitate the orientation of the pigment substantially parallel to the surface on which the application takes place.

Advantageously, the spectral reflectance of the pigment is between 10 and 70%, for the entire visible spectrum.

The subject of the invention is also a cosmetic or dermatological composition comprising such a pigment as well as a physiologically acceptable medium.

This cosmetic composition may comprise a mattifying filler, chosen for example from the following non-limiting list: talc, mica, silica, kaolin, NYLON (registered trademark), ORGASOL (registered trademark), polyethylene, TEFLON (trademark) powders. registered), starch, boron nitride, microspheres of copolymers such as EXPANCEL (registered trademark) or POLYTRAP (registered trademark), microbeads of silicone resins such as for example TOSPEARL (registered trademark), crosslinked silicone polymers such as for example KSG 6 or KSG 16 marketed by the company SHINETSU or TREFILS 505C marketed by the company DOW CORNING. The filler can be in a proportion of between 0 and 35%, preferably from 5 to 15% by weight relative to the total weight of the composition.

The multilayer structure may include layers made in materials chosen from the following non-exhaustive list:

- MgF ₂ , CeF ₃ , ZnS, ZnSe, Si, Ge, Te, SiO ₂ , Fe ₂ O ₃ , Pt, Va, Al ₂ O ₃ , MgO, Y ₂ O ₃ , S ₂ O ₃ , SiO, HfO ₂ , ZrO ₂ , CeO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , Ag, Al, Au, Cu, Rb, Ti, Ta, W, Zn, cryolite, alloys, polymers and their associations. In general, the structure is composed of an alternation of base index and high index layers, the low index layers being in particular dielectric layers and the high index layers of metal layers.

The composition can also contain water, organic solvents, waxes, oils, gelling agents, perfumes, cosmetic or dermatological active agents, rheology agents, surfactants or preservatives.

The subject of the invention is also a method of manufacturing a cosmetic composition incorporating such a pigment, characterized in that it comprises the steps consisting in:

measuring, for at least part of the visible spectrum, the spectral reflectance of the skin or of the keratin fibers of the subject for which the composition is intended,

- Producing an interference pigment to be incorporated into said composition, this pigment having a multilayer structure having a spectral reflectance close to the spectral reflectance previously measured.

Thus, it is possible to make to measure thanks to the invention a cosmetic composition perfectly suited to the color of the skin or of the user's keratin fibers.

The invention will be better understood on reading the detailed description which follows, of nonlimiting examples of implementation, and on examining the appended drawing in which: FIG. 1 represents the spectral reflectance of different types of skin, percentage of light reflected on the ordinate and wavelength in nm on the abscissa,

FIG. 2 illustrates the multilayer structure of a pigment particle, and

- Figure 3 shows the spectral reflectance of two cosmetic compositions according to the invention, percentage of light reflected on the ordinate and wavelength in nm on the abscissa.

In general, the optical properties of the skin are different depending on the origin of the subject and, by way of example, the reflectance is shown in FIG. 1 spectral of the skin for a Caucasian (C curve) and mixed race (M curve) subject, as a function of the wavelength of the incident radiation.

We can usefully refer to the subject in the article Skin Color Topology and Suntanning Pathways by A. Chardon et al. published in International Journal of Cosmetic Science 13, 191-208 (1991).

In the description which follows, it is considered that the visible spectrum comprises all the wavelengths between 400 nm and 700 nm.

The pigment according to the invention takes account of the spectral reflectance of the subject's skin. It allows a foundation to be produced whose spectral reflectance approaches that of the subject's skin or differs therefrom in a predetermined manner in order to attenuate a particular shade of color, for example yellow.

The pigment according to the invention can be mixed with a binder and optionally with other pigments, interference or otherwise, with one or more mattifying fillers and / or with one or more substances having a cosmetic and / or therapeutic effect on the skin and / or keratin fibers and / or the body.

By pigment, it is necessary to understand, in accordance with the usual definition, a substance insoluble in the medium (here physiologically acceptable) in which it is found and endowed with a coloring power. The pigment according to the invention has a multilayer structure, the different layers of which are chosen and arranged so that the spectral reflectance of the assembly has a predetermined appearance, for all or part of the visible spectrum.

FIG. 2 illustrates a multilayer structure comprising a succession of p layers of respective refractive indices n _1? n ₂ , n ₃ , ..., n _p-1 , n _p , of respective thicknesses e _1? e ₂ , e ₃ , ..., e _p-1 , e _p , the total thickness being equal to e.

Each elementary particle of pigment is assumed to be surrounded by a binder whose refractive index is n ₀ .

An incident ray I arriving on the multilayer structure with the incidence i gives rise to a part T which is transmitted and a part R which is reflected.

Refractive indices n _1; ..., n _p of the different layers as well as their respective thicknesses are chosen by applying the well-known theory of filters interference, so that the spectral reflectance and / or spectral transmittance of the multilayer structure has the desired properties.

Generally, the multilayer structure comprises an alternation of layers of high and low refractive indices, the high index layers being constituted for example by a metal oxide and the low index layers by a metal.

Surprisingly, it is possible to produce with a relatively small number of layers an interference pigment whose spectral reflectance is relatively close to that of a predetermined skin type, Caucasian or other.

The thickness of the elementary particles of the pigment is very small compared to their largest dimension and in any event compatible with their use in a makeup product.

By way of example, a pigment was produced having the multilayer structure given in table A below:

TABLE A

La structure multicouche comporte huit couches dont quatre couches de Al₂O₃ et quatre couches de Au disposées en alternance avec les couches de Al₂O₃.

The multilayer structure comprises eight layers including four layers of Al ₂ O ₃ and four layers of Au arranged alternately with the layers of Al ₂ O ₃ .

The thicknesses indicated in the table are approximate. The precision on the thickness is +/- 0.1 nm.

A pigment was also produced having the symmetrical multilayer structure given in Table B below.

TABLE B

La structure comporte treize couches dont sept couches de Al₂O₃ et six couches de Au disposées en alternance avec les couches Al₂O₃.

The structure comprises thirteen layers including seven layers of Al ₂ O ₃ and six layers of Au arranged alternately with the layers Al ₂ O ₃ .

The thicknesses of the layers are chosen so that the multilayer structure has the same reflectance, regardless of the end layer on which the incident light arrives.

FIG. 3 shows in broken lines the spectral reflectance of reference R _f which one seeks to imitate by means of the pigment.

The pigment particles are assumed to be dispersed in a binder whose refractive index n ₀ is equal to 1.5. A resin such as that sold by the company EASTMAN under the trade names EPOLENE Cl 6 or Cl 8 can be used to promote the orientation of the pigments.

In this figure, the curve R _A represents the spectral reflectance of the multilayer structure corresponding to table A and the curve R _B represents the spectral reflectance of the multilayer structure corresponding to table B. We have assumed in the case of the multilayer structure corresponding to board

A that all the elementary particles of pigment had the same orientation, the incident light arriving on the first layer of Al ₂ O ₃ .

In practice, the pigment particles can be found upside down, that is to say that the first layer which receives the light is the last layer of Au and not the first layer of Al ₂ O ₃ .

However, and surprisingly, the spectral reflectance of the pigment particles arranged upside down remains very close to that of the pigment particles arranged upside down, so that it is not a problem that the particles are dispersed without particular orientation (reverse or place) in the binder. In the case of the multilayer structure corresponding to Table B, the problem of the orientation of the particles does not arise since the multilayer structure is symmetrical.

Unexpectedly, if the thicknesses of the layers constituting the multilayer structures of Tables A and B vary by 1 or 2 nm, the spectral reflectance remains relatively little modified.

In other words, we can admit fairly large manufacturing tolerances for the different layers making up the multilayer structure while having a relatively stable spectral reflectance.

Thus, the pigment can be produced without having to use complicated techniques to measure with great precision the thicknesses of the deposits during manufacture. In the examples which have just been described, it is sought to reproduce at best the reference spectral reflectance R _f which corresponds to the spectral reflectance of the skin type of a user.

In other words, it is sought that the spectral reflectance of the multilayer structure is between minimum R _mm and maximum R _max curves not deviating by more than 10%, for example from the curve R _f .

However, it is not going beyond the scope of the present invention when the reference spectral reflectance R _f deviates appreciably from the spectral reflectance of the user's skin type in a given part of the visible spectrum in order to correct certain dominance thereof. chromatic. The reference spectral reflectance can thus be chosen so as to have a lower reflectance in yellow than that of the user for example. FIG. 3 shows a corrective spectral reflectance R _c deviating from the above-mentioned reference spectral reflectance R _f for the part of the spectrum between 450 and 500 nm. For the rest of the visible spectrum, the curve R _c merges substantially with the curve R _f .

The multilayer structure can be produced by depositing the successive layers of the required materials on a flexible support. The coating thus formed is then separated from the support in order to fragment it and to produce the elementary pigment particles. The deposition of the various layers can be carried out on a polymer soluble in a given solvent, this polymer having been previously deposited on a flexible support.

All the known techniques of vacuum deposition can be used, for example the techniques of evaporation, ion plating, spraying.

(sputtering), chemical vapor deposition possibly assisted by plasma (PCVD), by ionized clusters (ICB), epitaxy by molecular jets, ion bombardment, this list being of course not limiting.

We could refer for example to the European patent application EP-A-0 227 423 which describes a process making it possible to produce pigments made up of elementary particles having a multilayer structure.

In the embodiments described, the multilayer structure is substantially non-goniochromatic for incidences less than 45 °. In other words, in the color space L * (clarity), a * (red) and b *

(yellow), the parameters a * and b * of the multilayer structure are substantially constant for angles of incidence ranging from 0 to 50 °.

For such angles of incidence, the parameters a * and b * can vary by less than 10% each. The parameter L * is also substantially constant for the same range of angles of incidence.

The pigment can represent between 0.01 and 50% by weight of the total weight of the composition, preferably between 0.5 and 25%.

The composition can of course include all the ingredients conventionally used in the cosmetic and dermatological field, without going beyond the ambit of the present invention. It can advantageously be in the form of a foundation, a concealer product, a product for making up the body, the nails, the hair, but also in the form of a care cream.

The pigment according to the invention advantageously enters into the composition of a foundation.

For example, the foundation having the following formulation was produced, by mixing in a conventional manner:

KSG 16 20 g

(polydimethyl organosiloxane crosslinked in polydimethylsiloxane 6 es) (gelling and mattifying agent)

Cyclopenta-dimethyl siloxane (oil) 29 g

Hydrogenated isoparaffin (oil) 10 g

Talc (filler) 6 g

Pigment Example A 10 g Modified hectorite (gelling clay) q.s.p. 100g.

The invention makes it possible to produce compositions having a high covering power while giving the made-up skin a natural appearance, rendering the presence of the composition difficult to detect.

It is possible to play not only on spectral reflectance but also on spectral transmittance by appropriately choosing the different layers of the multilayer structure of the pigment.

The invention makes it possible to produce different colors by means of a set of pigments which differ from each other only in the number and the thicknesses of the layers of the multilayer structure.

The formulation of the cosmetic and / or dermatological compositions is thus easier to establish for a range of shades than with the pigments of the prior art.

Claims

1. Interference pigment having a multilayer structure, characterized in that the multilayer structure has a spectral reflectance (R _A ; R _B ) close to a reference spectral reflectance (R _f ; R _c ) corresponding to a skin type or of materials, especially fibers, predetermined keratin, for at least part of the visible spectrum. 2. Pigment according to claim 1, characterized in that the multilayer structure has a spectral reflectance (R _A ; R _B ) close to a reference spectral reflectance (R _f ) corresponding to a type of skin or materials, in particular of predetermined keratin fibers, for the entire visible spectrum. 3. Pigment according to claim 1 or 2, characterized in that the type of skin concerned is the Caucasian, mixed race, black, or Asian type. 4. Pigment according to any one of claims 1 to 3, characterized in that the spectral reflectance (R _A ; R _B ) of the multilayer structure deviates, for the range of the visible spectrum considered, by at most + / - 10% of the reference spectral reflectance (R _f ). 5. Pigment according to any one of the preceding claims, characterized in that the reference spectral reflectance (R _c ) has, for at least certain wavelength values, a reflectance chosen to attenuate a chromatic dominant of the type of skin considered. 6. Pigment according to claim 5, characterized in that the dominant color which is attenuated is yellow. 7. Pigment according to any one of the preceding claims, characterized in that the said multilayer structure is arranged so as to be substantially non-goniochromatic for incidences less than 45 °. 8. Pigment according to any one of the preceding claims, characterized in that the multilayer structure is arranged to present a clarity parameter L substantially constant for incidences less than 45 °. 9. Pigment according to any one of the preceding claims, characterized in that it comprises an odd number (p) of layers. 10. Pigment according to any one of the preceding claims, characterized in that the multilayer structure is symmetrical. 11. Pigment according to any one of the preceding claims, characterized in that the largest dimension of the elementary pigment particles is between 10 and 50 μm. 12. Pigment according to any one of the preceding claims, characterized in that the spectral reflectance of the pigment is between 10 and 70%, for the entire visible spectrum. 13. Pigment according to any one of the preceding claims, characterized in that the multilayer structure comprises layers made of materials chosen from the following list: - MgF ₂ , Ce'Fa, ZnS, ZnSe, Si, Ge, Te, SiO ₂ , Al ₂ O ₃ , MgO, Y ₂ O ₃ , S ₂ O ₃ , SiO, HfO ₂ , ZrO ₂ , CeO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , Ag, Al, Au, Cu, Rb, Fe ₂ O ₃ , Pt, Va, Ti, Ta, Zn, cryolite, alloys, polymers and their associations. 14. Method for manufacturing a cosmetic composition incorporating a pigment, characterized in that it comprises the steps consisting in: - measuring, for at least part of the visible spectrum, the spectral reflectance of the skin or of the materials, in particular fibers, keratinous of the subject for which the composition is intended, - producing an interference pigment to be incorporated into said composition, this pigment having a multilayer structure having a spectral reflectance close to the spectral reflectance previously measured. 15. Cosmetic and / or dermatological composition incorporating a pigment as defined in any one of claims 1 to 13. 16. Foundation incorporating a pigment as defined in any one of claims 1 to 13. 17. Use of the cosmetic composition as defined in claim 15 by a person whose skin type is substantially the same as that to which the reference spectral reflectance (R _f ) corresponds. 18. Use of the composition as defined in claim 15 for concealing wrinkles, fine lines, spots, blotchiness, veins and blackheads. 19. Use of the composition as defined in claim 15 for concealing gray hair. 20. Use of a pigment according to any one of claims 1 to 13 in a cosmetic composition or for the manufacture of a physiologically acceptable composition for concealing imperfections in the skin or in materials, in particular keratin fibers.