FR3150107A1 - Use of a composite material of bismuth oxycarbonate and inorganic compounds for the filtration of ultraviolet radiation - Google Patents

Abstract

Use of a composite material of bismuth oxycarbonate and inorganic compounds for the filtration of ultraviolet radiation The present invention relates to the use of a composite material comprising at least a) particles of bismuth oxycarbonate of formula (I) (BiO)2-x(CO3), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M(v) y)p Oz(OH)t]q (H2O)w; for the filtration of UV-A rays, and/or UV-B rays, preferably UV-B rays, as well as composite materials, their preparation process, and compositions using them. Figure for the abstract: None

Description

Use of a composite material of bismuth oxycarbonate and inorganic compounds for the filtration of ultraviolet radiation

The present invention relates to the field of sun protection and more particularly to the use of composite materials of bismuth oxycarbonate, as well as its solvates, such as its hydrates, and inorganic compounds, for the filtration of ultraviolet radiation.

The invention also relates to composite materials of bismuth oxycarbonate, as well as its solvates, such as its hydrates, and inorganic compounds, and compositions, in particular cosmetic compositions, comprising such materials.

Keratin materials are exposed to sunlight on a daily basis.

It is known that light rays with wavelengths between 280 nm and 400 nm allow the tanning of human epidermis. However, rays with wavelengths between 280 and 320 nm, called UV-B rays, are detrimental to the development of a natural tan. This exposure is also likely to induce an alteration of the biomechanical properties of the epidermis which results in the appearance of wrinkles leading to premature aging of the skin.

It is also known that UV-A rays, with wavelengths between 320 and 400 nm, penetrate deeper into the skin than UV-B rays. UV-A rays promote rapid and persistent pigmentation of the skin. Daily exposure to UVA radiation, even for short periods, under normal conditions, can also cause a degradation of collagen and elastin fibers, resulting in a change in the skin microrelief, the appearance of wrinkles and irregular pigmentation (i.e. brown spots, uneven skin tone, etc.).

Additionally, prolonged exposure to the sun can further dry out hair, making it brittle.

Therefore, protection of keratin materials, particularly human ones, such as skin, is essential.

To counter these undesirable effects, it is common practice to formulate organic and/or inorganic UV-A and/or UV-B filters in compositions dedicated to providing sun protection.

Many skin photoprotective cosmetic compositions have been proposed to date. They generally contain organic UV filters and/or inorganic UV filters which act according to their own chemical nature and according to their own physical properties by absorption, reflection or diffusion of UV radiation. They generally contain combinations of oil-soluble organic UV filters and/or water-soluble organic UV filters associated with metal oxide pigments such as titanium dioxide (TiO ₂ ) or zinc oxide (ZnO).

As for the usual organic filters, they must have acceptable cosmetic properties, good solubility in usual solvents, particularly in oils, but also good photostability, alone and in combination. They must also be colorless or of a color cosmetically acceptable to consumers. These organic filters are generally used in mixtures and such combinations of filters can limit the formulatory field.

In addition, photoprotection from inorganic UV filters is today a very important expectation of consumers, as they consider mineral sunscreens safer.

_TiO2 and ZnO are the most common mineral UV filters used.

However, one of the major drawbacks of such mineral filters is that, once applied to the skin, they produce a whitening effect on the skin which is cosmetically undesirable and generally not appreciated by users.

This effect is all the more marked as the concentration of mineral filters in the composition is high, which limits their concentration in sun formulations.

To avoid this problem, it would of course be possible to use reduced quantities of inorganic filter(s), but the resulting compositions, which would certainly lead to films with acceptable transparency on the skin, would then no longer offer suitable protection in the UV range, which greatly limits the interest of such an option.

In addition, the use of large quantities of these UV filters induces, in addition to significant whitening, unpleasant sensations after application to the skin, and in particular causes sensations of roughness and dryness on the skin in the case of significant and regular use of the products.

However, consumers are increasingly looking for products that are effective but also easy to apply, provide long-lasting comfort and have satisfactory sensory properties.

There therefore remains a need for inorganic UV filters which are effective in photoprotection and which do not have the drawbacks presented above.

In particular, there remains a need for inorganic UV filters capable of effectively blocking UV rays, particularly in the UV-B and UV-A range, and in particular UV-B rays, having high transparency to visible light, which do not bleach the keratin materials to which they are applied and having good cosmetic properties.

In particular, there remains a need for mineral UV filters, distinct from titanium dioxide or zinc oxide, which are just as effective, which are transparent, which do not cause a feeling of roughness and drying on the skin, and which are easily formulated, particularly at high concentrations.

The present invention aims precisely to propose new mineral UV filters making it possible to meet these expectations.

Thus, according to a first of its aspects, the present invention relates to the use of a composite material comprising:

(a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ) , as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm; and

b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w ;

in which:

- y is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably y is less than 10, more preferably less than 5, and even more preferably y denotes 1 or 2 or 3;

- z is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably z is less than 10, more preferably less than 5;

- t is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably t is less than 10, more preferably t is less than 5;

- M is a metal, an alkaline earth metal or a metalloid, preferably chosen from silicon Si, titanium Ti, iron Fe, zinc Zn, niobium Nb, tantalum Ta, cerium Ce, manganese Mn, bismuth Bi, tungsten W, aluminum Al, copper Cu and indium In, preferably M denotes Si or Al;

- v denotes the degree of oxidation of M and is a number between 1 and 8, preferably v is less than or equal to 6, and more preferably less than or equal to 4;

- w is an integer or fractional number ranging from 0 to 20;

- p is an integer ranging from 1 to 5, preferably p is less than or equal to 3, more preferably less than or equal to 2, even more preferably equal to 1;

- q is an integer ranging from 1 to 5, preferably q is less than or equal to 2, more preferably q is equal to 1; and

- for each inorganic compound: ;

for the filtration of UV-A rays, and/or UV-B rays, preferably UV-B rays, particularly for protecting keratin materials, in particular human materials such as skin, and/or keratin fibres, in particular human materials such as hair;

provided that when b) is TiO ₂ , then the composite material is in the form of “core / shell ” .

Preferably the average size of the largest particle dimension of said composite material is less than or equal to 450 nm.

Preferably, the average size of the largest dimension of the composite material particle varies from 10 nm to 300 nm, preferably from 25 nm to 250 nm, and more preferably from 40 nm to 200 nm.

Another object of the invention is a composite material comprising:

Let i):

- a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, as defined above; and

- a shell comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w are as defined above;

Either ii):

- a core comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w are as defined above;

- a shell comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, such as the hydrates as defined above;

- it being understood that the average size of the largest particle dimension of composite material is less than or equal to 450 nm.

Surprisingly, and as is apparent from the examples below, the inventors have discovered that the composite materials according to the invention exhibit excellent efficiency for filtering ultraviolet radiation, and in particular UV-B rays, as well as high transparency in visible radiation, and make it possible to give the composition containing them cosmetic properties that are satisfactory for the consumer.

For the purposes of the present invention, the term “ composite material ” means a heterogeneous particulate solid material comprising at least two immiscible components, the components of which are linked by physical and/or chemical interactions.

For the purposes of the present invention, the term " high transparency in visible radiation " means particles having a high transmission of rays between 400 and 780 nm.

For the purposes of the present invention, the term " efficiency for filtering ultraviolet radiation " means particles having an absorbance threshold in the UV, in the dispersion medium comprising said particles at a mass fraction of 0.005%, greater than 0.25, preferably greater than or equal to 0.30, and more preferably still greater than or equal to 0.35. The higher the absorbance threshold, the greater the efficiency of filtering UV radiation.

UV-B radiation means the wavelength range from 280 to 320 nm. UV-A radiation means the wavelength range from 320 to 400 nm. Visible light means the wavelength range from 400 to 780 nm.

Thus, for the purposes of the present invention, the term " UV filter " is intended to denote any compound that filters ultraviolet (UV) radiation in the wavelength range from 280 nm to 400 nm. The term " UV-B filter " is intended to denote any compound that filters ultraviolet (UV) radiation in the wavelength range from 280 nm to 320 nm. The term "UV-A filter" is intended to denote any compound that filters ultraviolet (UV) radiation in the wavelength range from 320 nm to 400 nm.

This efficiency of the composite materials according to the invention is, to the knowledge of the inventors, characterized for the first time. It has never been proposed to use composite materials of bismuth oxycarbonate a), as well as its solvates, such as its hydrates, and inorganic compounds b), as defined above, for the effective filtration of UV radiation, in particular UV-B radiation.

The uses and composite materials according to the invention are in particular intended to protect keratin materials, in particular the skin and hair, from UV radiation, in particular in cosmetic compositions for the fields of sun protection, care, hair treatment and makeup.

Thus, according to another aspect, the present invention also relates to the non-therapeutic cosmetic use of a composite material comprising at least a) bismuth oxycarbonate particles of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above, for filtering UV radiation, preferably UV-B, comprising at least the application to keratin materials, in particular human, such as the skin and/or keratin fibers, such as the hair, of said composite material preferably being in a composition, preferably cosmetic.

The present invention also relates to a non-therapeutic cosmetic process for filtering UV radiation, preferably UV-B, comprising at least the application to keratin materials of a composition comprising composite materials comprising at least a) bismuth oxycarbonate particles of formula (I) (BiO) _{2- x} (CO ₃ , as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above.

The present invention also relates to methods of preparing the composite materials according to the invention.

By “ keratin materials ” we mean in particular the skin, including the scalp, the lips, and also keratin fibres such as the hair, eyelashes, eyebrows, in particular the skin and/or the hair, and preferably the skin.

The expression " at least one " is equivalent to " one or more ".

The expressions “ between … and … ”, “ includes from … to … ”, “ formed from … to … ”, and “ ranging from … to … ” must be understood inclusively, unless otherwise specified.

Other characteristics, variants and advantages of the compositions according to the invention will emerge more clearly upon reading the description and examples which follow.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material A at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material B at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material C at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material D at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material E at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material F at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material G at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material H at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material I at 0.005% by mass in bismuth oxycarbonate in a Water / Propylene Glycol / Polysorbate 20 mixture.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material J at 0.005% by mass in bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material Y outside the invention at 0.005% by mass of bismuth oxycarbonate in water.

represents the absorbance spectrum obtained by UV-visible spectrophotometry on dispersions of composite material Z outside the invention at 0.005% by mass in bismuth oxycarbonate in water.

Detailed description

As previously indicated, the composite material comprises at least a) a particle of bismuth oxycarbonate, as well as its solvates, such as its hydrates, and b) at least one inorganic compound of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which:

- y is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably y is less than 10, more preferably less than 5, and even more preferably y denotes 1 or 2 or 3;

- z is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably z is less than 10, more preferably less than 5;

- t is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably t is less than 10, more preferably t is less than 5;

- M is a metal, an alkaline earth metal or a metalloid, preferably chosen from silicon Si, titanium Ti, iron Fe, zinc Zn, niobium Nb, tantalum Ta, cerium Ce, manganese Mn, bismuth Bi, tungsten W, aluminum Al, copper Cu and indium In, preferably M denotes Si or Al;

- v denotes the degree of oxidation of M and is a number between 1 and 8, preferably v is less than or equal to 6, and more preferably less than or equal to 4;

- w is an integer or fractional number ranging from 0 to 20;

- p is an integer ranging from 1 to 5, preferably p is less than or equal to 3, more preferably less than or equal to 2, even more preferably equal to 1;

- q is an integer ranging from 1 to 5, preferably q is less than or equal to 2, more preferably q is equal to 1; and

- for each inorganic compound: .

Thus, the composite material according to the invention can be represented according to the formula [(BiO)_{2- x} CO₃] - [(M ^{( v )} _y ) _p O _z (OH) _t ] _q (H₂O) _w in whichx, M,v,y,p,z,t,qAndware as defined above.

The average size of the largest dimension of the composite material particle is less than or equal to 450 nm.

In particular, the average size of the largest dimension of the composite material particle varies from 10 nm to 300 nm, preferably from 25 nm to 250 nm, and more preferably from 40 nm to 200 nm.

By " average size " is meant the number-average value of the dimensions of the primary particles. The particle dimensions can be determined by transmission electron microscopy, for example using a Hitachi HT 7700 microscope, in particular at an acceleration voltage of 100 kV, by scanning electron microscopy, or from the measurement of the specific surface area by the BET method, or by means of a laser particle size analyzer. Preferably, the particle dimensions are determined by transmission electron microscopy, for example using a Hitachi HT 7700 microscope, in particular at an acceleration voltage of 100 kV, or by scanning electron microscopy.

Preferably, the measurement is made on the smallest individualized or individualizable objects. The mean value in number can be calculated by analysis of the images obtained using software, such as Image J software (C.A. Schneider, W.S. Rasband, K.W. Eliceiri, NIH Image to ImageJ: 25 years of image analysis, Nat. Methods. 9 (2012) 671–675).

The average dimension is chosen from the average length L, the average width l, the average thickness e, or the average diameter d.

By " the average size of the largest dimension " or " the average largest dimension " of composite materials or particles is meant the largest average dimension of a surface, such as a face, that can be measured between two diametrically opposite points of an individual particle.

The “ length ” L of a composite material or particle is its largest dimension observable on a photograph taken in a direction perpendicular to the plane on which said composite material or particle rests.

The " width " l and " thickness " e of a composite material or particle are the lengths of the major and minor axes, respectively, of the smallest possible ellipse in which the median cross-section of said composite material or particle can be inscribed .

The " diameter " d of a composite material or particle is the largest dimension observable along a line passing through the center of a circle or sphere.

The composite materials according to the invention can be of various shapes and structures.

The composite materials according to the invention may in particular be spherical, cubic, platelet-like, cylindrical or tubular.

The shape of said composite materials will depend in particular on their preparation process and the operating conditions.

In particular, the composite materials according to the invention may be in the form of tubes, platelets, sheets, rods, spheres, flowers, pompoms, threads, filaments, fibers, needles, cubes or any of their mixtures.

The composite materials according to the invention can furthermore aggregate in the form of superstructures. For example, platelets, tubes and/or rods can aggregate in the form of spheres, flowers or even pompoms.

According to a particular embodiment, the composite materials according to the invention are in the form of spheres.

According to a particular embodiment, the composite materials according to the invention are in the form of tubes, plates and/or rods. Even more preferably, the composite materials according to the invention are in the form of plates and/or rods.

Composite materials in the form of plates or rods or tubes are therefore distinguished in particular from spherical, fibrous shapes, flowers, pompoms, threads, filaments, needles or cubes.

It is understood that the composite materials according to the invention can be used in the form of a mixture. In particular, the composite materials according to the invention can be used in a mixture in any proportion of platelets and/or rods and/or tubes.

According to a preferred embodiment, the composite materials used according to the invention are mainly or exclusively in the form of platelets.

A composite material in the form of a " platelet " has a length greater than its width and a width greater than its thickness.

According to a preferred embodiment, the composite materials are mainly or exclusively in the form of rods.

A composite material in the form of a " rod " has a solid cylindrical shape and its length L is greater than its diameter d , or has a prism shape whose base is solid polygonal, preferably triangular or hexagonal, and the diameter d of the circle circumscribed to this polygonal base is less than the length L of the prism.

According to a preferred embodiment, the composite materials are mainly or exclusively in the form of tubes.

A composite material in the form of a “ tube ” has a hollow cylindrical shape and its length L is greater than its diameter d .

For the purposes of the present invention, the term " predominantly in the form of platelets/rods/tubes " means that at least 50% by number, in particular at least 70% by number, or even at least 90% by number of the composite materials are in the form of platelets/rods/tubes respectively.

According to one embodiment, the composite material comprises:

Let i):

- a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, as defined above; and

- a shell comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w are as defined above;

Either ii):

- a core comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w are as defined above;

- a shell comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, such as the hydrates as defined above;

- preferably, it being understood that the average size of the largest particle dimension of composite material is less than or equal to 450 nm.

In other words, the composite material includes:

- a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, or b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w ; and

- a shell comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm or b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w ;

in which M ^(v) _y , p, z, t, q, and w are as defined previously,

it being understood that:

- said material contains at least one particle a) and at least one inorganic compound b); and

- preferably, the average size of the largest particle dimension of composite material is less than or equal to 450 nm.

Preferably, the composite material according to the invention comprises:

- a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, as defined above; and

- a shell comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w are as defined above;

preferably, the average size of the largest particle dimension of composite material being less than or equal to 450 nm.

According to one embodiment, the composite material according to the invention comprises:

- a core comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w are as defined above; and

- a shell comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, as defined above;

preferably, the average size of the largest particle dimension of composite material being less than or equal to 450 nm.

Preferably, the bark consists of one or more species of inorganic compounds b) chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M, v , y , p , z , t , q and w are as defined above.

Preferably, the shell consists of one or more species of inorganic compounds b) chosen from the oxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M, v , y , p , z , t , q and w are as defined above.

Preferably, the bark covers all or part of the heart.

According to a particular embodiment, the molar ratio between the number of moles of compound(s) [(M ^(v) _y ) _p O _z (OH) _t ] _q (H₂O) _w or respectively [(BiO)_{2- x} CO₃] constituting the bark and the number of compound moles constituting the core [(BiO)_{2- x} CO₃] or respectively [(M ^(v) _y ) _p O _z (OH) _t ] _q (H₂O) _w varies from 0.0001 to 20, preferably from 0.005 to 10, better from 0.01 to 5, even better from 0.02 to 2, and even more preferably from 0.05 to 1.

The bark can be made up of a single layer or of several identical or different layers, totally or partially superimposed.

Preferably, the bark consists of a single layer covering all or part of said core.

According to a particular embodiment, the core-shell composite materials according to the invention contain a majority fraction, namely greater than 50% by number, of composite materials having a core consisting of a single particle of bismuth oxycarbonate (BiO) ₂ CO ₃ , as well as its solvates, such as its hydrates, the largest dimension of which is less than 400 nm.

According to another particular embodiment, the core-shell composite materials according to the invention contain a majority fraction, namely greater than 50% by number, of composite materials having a core consisting of inorganic oxides [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w .

In other words, the core-shell composite materials according to the invention preferably contain a core consisting of a single particle.

Preferably, the average size of the largest dimension of the core varies from 1 to 400 nm.

Preferably, the thickness of the bark varies from 1 to 449 nm, preferably from 1 to 300 nm, more preferably from 1 to 200 nm.

In the context of the uses and methods according to the invention described below, the bismuth oxycarbonate particle(s) a), as well as its solvates, such as its hydrates, and the inorganic compound(s) b) can be arranged in different ways within the composite material.

According to one embodiment, the composite material may have at least one core and at least one layer(s) coating surrounding said core.

Thus, they may comprise at least one coating in layer(s) surrounding a core chemically different from said coating.

The coating can be formed of one or more layers.

The core of the composite materials may consist of at least a) one or more particles of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm.

According to a particular embodiment, the core of the composite materials may consist of at least one inorganic compound b).

The composite material may contain bismuth oxycarbonate particles a) as defined above in the core and/or in the layer(s) forming the coating.

According to a particular embodiment, the material contains at least one particle of bismuth oxycarbonate a), as well as its solvates, such as its hydrates, as defined above in the core.

According to another particular embodiment, the material contains particles of bismuth oxycarbonate a), as well as its solvates, such as its hydrates, as defined above in the coating.

According to one embodiment, the inorganic compound(s) b) may cover all or part of at least one particle of bismuth oxycarbonate a), as well as its solvates, such as its hydrates.

According to another embodiment, the inorganic compound(s) b) may be covered in whole or in part by at least one particle of bismuth oxycarbonate a), as well as its solvates, such as its hydrates.

In particular, the molar ratio between the number of moles of coating compound(s) and the number of moles of core compound(s) varies from 0.0001 to 20, preferably from 0.005 to 10, better still from 0.01 to 5, even better still from 0.02 to 2, and even more preferably from 0.05 to 1.

According to a particular embodiment, the composite materials according to the invention contain at least one layer surrounding the core.

Thus, according to a particular embodiment, the composite materials according to the invention comprise a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, said core being covered on the surface, continuously or discontinuously, by a coating comprising at least one inorganic compound b) as defined above.

According to a first variant of the invention, the composite materials in accordance with the invention comprise a coating, also called a continuous shell or envelope, i.e. surrounding the entire surface of the core.

According to a second variant of the invention, the composite materials in accordance with the invention comprise a coating, also called a bark or envelope, which is discontinuous, i.e. discontinuously surrounding the surface of the core.

Preferably, from 10% to 90%, more particularly from 10% to 70%, and even more particularly from 30% to 50% of the surface of the core is covered by the coating.

According to one embodiment, the coating is a multilayer coating, that is to say comprising one or more internal layers and an external layer, in other words several superimposed layers for all or part of which each can be continuous or discontinuous.

In a multi-layer coating, the term " inner layer " means any layer that is not an outer layer. This may be the layer directly superimposed on the core or any intermediate layer between the core and the outer layer.

In a multi-layer coating, the term " outer layer " means the layer forming the last layer of the coating that is not contiguous with the core. The outer layer is separated from the core by at least one inner layer. The outer layer has no coating.

In a multilayer coating formed of two layers, the inner layer is the layer contiguous to the core and the outer layer is the layer contiguous to the inner layer and not contiguous to the core.

In a multilayer coating formed of more than two layers, the inner layers are the layer adjacent to the core and the intermediate layer(s) between the layer adjacent to the core and the outer layer.

The inner layer(s) forming the multi-layer coating of the composite material and the single outer layer of the composite material may be formed from the same or different compounds.

Each layer can consist of a single compound or a mixture of compounds.

The layer(s) may in particular extend concentrically relative to the core.

In particular, the composite materials according to the invention have a double layer surrounding the core, in other words an internal layer and an external layer.

According to a preferred embodiment, the composite materials according to the invention have at least one layer, preferably comprising at least one inorganic compound b) as defined above.

According to a preferred embodiment, the composite materials according to the invention comprise:

- a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, and

- at least one layer continuously or discontinuously surrounding said core and comprising at least one inorganic compound b) as defined above,

and the average size of the largest particle dimension of composite material being less than or equal to 450 nm.

Preferably, the composite materials according to the invention comprise:

- a core comprising a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm,

- a single layer contiguous to said core and comprising at least one inorganic compound b) as defined above;

it being understood that the average size of the largest particle dimension of composite material being less than or equal to 450 nm.

a) Bismuth oxycarbonate particles

The bismuth oxycarbonate particles a) according to the invention are of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, with -0.4 < x < 0.6. The value of x can in particular be determined by elemental analysis.

Preferably, x is 0 and the empirical formula of bismuth oxycarbonate particles is (BiO) ₂ ( _CO3 ), as well as its solvates, such as its hydrates.

The bismuth oxycarbonate particles according to the invention may be crystallized or amorphous.

According to one form of the invention, the bismuth oxycarbonate particles a) are amorphous.

According to a preferred form of the invention, the bismuth oxycarbonate particles a) are crystallized.

It is understood that the bismuth oxycarbonate particles may consist of a mixture of several bismuth oxycarbonate particles of different raw formulas and/or different shapes.

Thus, bismuth oxycarbonate particles can be a mixture of amorphous particles and crystalline particles.

By " crystallized " as used herein is meant that the atoms constituting the bismuth oxycarbonate particles are arranged in an orderly manner. In other words, the crystallized bismuth oxycarbonate particles are organized materials.

In contrast, " amorphous " particles are particles whose atoms are disordered. The atoms of such particles have no organization in the microscopic state.

Preferably, the crystallized particles required according to the invention have the crystalline phase of the natural ore bismutite, referred to as lamellar, and which has an alternation of [Bi ₂ O ₂ ] ²⁺ and [CO ₃ ] ^2- layers.

Such particles crystallize in an orthorhombic system of space group Imm2 .

The bismutite crystal structure of bismuth oxycarbonate can have the following lattice parameters: a = 3.865 Å; b = 3.862 Å; c = 13.675 Å and V _lattice = 0.204 nm ³ . This particular arrangement of atoms allows in particular the growth of anisotropic objects.

A particle is considered "anisotropic" when the elongation factor R between its length L and its thickness e , i.e. R = L / e , is greater than 2.

According to the invention, the largest average dimension of the crystallized or amorphous, preferably crystallized, particles of bismuth oxycarbonate a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6 is less than 400 nm.

Preferably, the largest average dimension of said particles is less than or equal to 300 nm.

According to the invention, the bismuth oxycarbonate particles a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, can be in any form.

The shape of said particles will depend in particular on their preparation process and the operating conditions.

In particular, the particles according to the invention may be in the form of tubes, platelets, sheets, rods, spheres, flowers, pompoms, threads, filaments, fibers, needles, cubes or any of their mixtures.

The particles according to the invention can further aggregate in the form of superstructures. For example, platelets, tubes and/or rods can aggregate in the form of spheres, flowers or even pompoms.

According to a preferred embodiment, the particles according to the invention are in the form of tubes, platelets and/or rods. Even more preferably, the particles according to the invention are in the form of platelets and/or rods.

Particles in the form of platelets or rods or tubes are therefore distinguished in particular from spherical, fibrous forms, flowers, pompoms, threads, filaments, needles or cubes.

It is understood that the particles according to the invention can be used in the form of a mixture. In particular, the particles according to the invention can be used in a mixture in any proportion of platelets and/or rods and/or tubes.

According to a preferred embodiment, the particles used according to the invention are mainly or exclusively in the form of platelets.

A particle in the form of a " platelet " has a length greater than its width and a width greater than its thickness.

In particular, when in the form of platelets, bismuth oxycarbonate particles a), as well as its solvates, such as its hydrates, possess:

- an average length L ranging from 15 to 300 nm, in particular ranging from 30 to 250 nm, preferably ranging from 50 to 200 nm, more preferably ranging from 70 to 150 nm;

- an average width l ranging from 10 to 250 nm, in particular ranging from 20 to 200 nm, preferably ranging from 30 to 150 nm, more preferably ranging from 50 to 120 nm;

- an average thickness e ranging from 2 to 120 nm, in particular ranging from 5 to 100 nm, preferably ranging from 10 to 80 nm, more preferably ranging from 20 to 50 nm; and

- with e < l < L .

According to a preferred embodiment, the bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, are predominantly or exclusively in the form of rods.

A particle in the form of a " rod " has a solid cylindrical shape and its length L is greater than its diameter d , or has a prism shape whose base is solid polygonal, preferably triangular or hexagonal, and the diameter d of the circle circumscribed to this polygonal base is less than the length L of the prism.

In particular, when in the form of rods, whether cylindrical or prismatic, bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, have:

- an average length L ranging from 30 to 300 nm, in particular ranging from 50 to 250 nm, preferably ranging from 70 to 230 nm, more preferably ranging from 70 to 140 nm;

- an average diameter d ranging from 15 to 150 nm, in particular ranging from 20 to 130 nm, preferably ranging from 25 to 120 nm, more preferably ranging from 25 to 100 nm, and even more preferably ranging from 25 to 60 nm, and

- with L > d .

According to a preferred embodiment, the bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, are predominantly or exclusively in the form of tubes.

A particle in the form of a " tube " has a hollow cylindrical shape and its length L is greater than its diameter d .

In particular, when in the form of tubes, bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, possess:

- an average length L ranging from 10 to 300 nm, in particular ranging from 20 to 250 nm, preferably ranging from 40 to 200 nm, more preferably ranging from 60 to 200 nm;

- an average diameter d ranging from 2 to 30 nm, in particular ranging from 3 to 20 nm, and preferably ranging from 5 to 15 nm; and

- with L > d .

For the purposes of the present invention, the term " predominantly in the form of platelets/rods/tubes " means that at least 50% by number, in particular at least 70% by number, or even at least 90% by number of the particles are in the form of platelets/rods/tubes respectively.

Particle doping a)

According to a particular embodiment, the bismuth oxycarbonate particles a), as well as its solvates, such as its hydrates, can be doped.

In particular, bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, can be doped with one or more chemical elements capable of being inserted into the structure or of partially replacing elements already present.

The particles can be doped via substitutions of all or part of the cations and/or all or part of the anions.

According to a particular embodiment, the doping partly concerns cations in insertion or substitution of bismuth within the limit of 20% of the bismuth composition.

According to this variant, the doping rate varies in particular from 0.005% to 15%, preferably from 0.05% to 12%, more preferably from 0.1% to 10%, and even more preferably from 0.5% to 6%.

In particular, the bismuth oxycarbonate particles a) may be doped with cations derived from elements selected from aluminum (Al), silicon (Si), scandium (Sc), titanium (Ti), vanadium (V), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), indium (In), lanthanum (La), cerium (Ce), tantalum (Ta), tungsten (W) and/or gold (Au).

Preferably, the bismuth oxycarbonate particles a) can be doped with cations from elements chosen from titanium, vanadium, manganese, iron, copper, zinc, lanthanum, and/or cerium, more preferably from manganese, iron and/or cerium, and even more preferably from manganese or iron.

According to an alternative embodiment, the bismuth oxycarbonate particles a) are doped with cations derived from manganese, and the doping rate varies in particular from 0.5% to 2%.

According to another embodiment, the bismuth oxycarbonate particles are doped with cations derived from iron, and the doping rate varies in particular from 0.5% to 2%.

According to another particular embodiment, the doping concerns in part or in total anions in insertion or in substitution of the carbonate group within the limit of 20% of the carbonate composition.

According to this variant, the doping rate varies in particular from 0.001% to 1%, preferably from 0.002% to 0.5%, more preferably from 0.003% to 0.2%, and even more preferably from 0.005% to 0.1%.

In particular, the bismuth oxycarbonate particles a) may be doped with anions derived from elements selected from fluorine (F), sulfur (S), chlorine (Cl), bromine (Br), iodine (I), and/or with polyatomic anions, in particular selected from sulfate ion (SO ₄ ^2- ), sulfonate ion (S(=O) ₂ -O ^- ), sulfite ion (SO ₃ ^2- ), phosphate ion (PO ₄ ^3- ) and/or iodate ion (IO ₃ ^- ).

Preferably, the bismuth oxycarbonate particles a) may be doped with S^2-, SO₃ ^2-, SO₄ ^2-, Cl^- and/or I^-, more preferably with SO₃ ^2-, SO₄ ^2-and/or Cl^-, and more preferably with Cl^-or SO₄ ^2-.

According to an alternative embodiment, the bismuth oxycarbonate particles a) are doped with anions derived from chlorine, and the doping rate varies in particular from 0.01% to 0.1%.

According to another embodiment, the bismuth oxycarbonate particles are doped with anions derived from iodine, and the doping rate varies in particular from 0.003% to 0.01%.

According to another embodiment, the bismuth oxycarbonate particles a) are doped with the sulfate ion, and the doping rate varies in particular from 0.005% to 0.1%.

According to another embodiment variant, the bismuth oxycarbonate particles a) are doped with cations preferably from elements chosen from titanium, vanadium, manganese, iron, copper, zinc, lanthanum, and/or cerium, more preferably chosen from manganese, iron and/or cerium, and even more preferably chosen from manganese or iron, and with anions preferably from elements chosen from fluorine (F), sulfur (S), chlorine (Cl), bromine (Br), iodine (I), and/or with polyatomic anions, in particular chosen from the sulfate ion (SO₄ ^2-), the sulfonate ion (S(=O)₂-O^-), the sulfite ion (SO₃ ^2-), the phosphate ion (PO₄ ^3-) and/or the iodate ion (IO₃ ^-), more preferably with S^2-, SO₃ ^2-, SO₄ ^2-, Cl^- and/or I^-, even more preferably with SO₃ ^2-, SO₄ ^2-and/or Cl^-, and particularly preferably with Cl^-, I^-or SO₄ ^2-.

According to a preferred embodiment, the bismuth oxycarbonate particles a), as well as its solvates, such as its hydrates, required according to the invention are undoped.

According to another preferred embodiment, the bismuth oxycarbonate particles a), as well as its solvates, such as its hydrates, required according to the invention are doped.

According to another preferred embodiment, the bismuth oxycarbonate particles a), as well as its solvates, such as its hydrates, required according to the invention are a mixture of doped particles and undoped particles.

Particle preparation process bismuth oxycarbonate a)

Bismuth oxycarbonate particles a), as well as its solvates, such as its hydrates, can be obtained by any preparation process known to those skilled in the art.

For example, the synthesis of bismuth oxycarbonate particles is described in the article by Ni et al. (Fabrication, modification and application of (BiO) ₂ CO ₃ -based photocatalysts: A review, Applied Surface Science, 365, 2016, 314–335).

In particular, bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, can be prepared solvothermally, electrochemically, by co-precipitation, or at reflux, and preferably solvothermally or at reflux.

According to a first embodiment variant, the bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, are obtained by solvothermal means, in particular from bismuth nitrate and various carbonating agents such as sodium carbonate, ammonium carbonate or urea, in a polar protic solvent in the presence of polyols. Such a synthesis makes it possible to obtain bismuth oxycarbonate particles in the form of platelets and/or rods, the largest dimension of which varies from 50 to 300 nm.

The synthesis of particles by solvothermal means is notably described in the articles of Cheng, G. et al. (Shape-controlled solvothermal synthesis of bismuth subcarbonate nanomaterials, J. Solid State Chem. 183, 1878–1883 (2010)); Ruan, M. M. et al. (Facile Green Synthesis of Highly Monodisperse Bismuth Subcarbonate Micropompons Self-assembled by Nanosheets: Improved Photocatalytic Performance, Acta Physico-Chimica Sinica, 33, 2017, 1033–1042); Quin et al. (Template‐Free Fabrication of Bi ₂ O ₃ and (BiO) ₂ CO ₃ Nanotubes and Their Application in Water Treatment, Chem. Eur. J., 18, 2012, 16491–16497); Cheng, G. et al. (Shape-controlled solvothermal synthesis of bismuth subcarbonate nanomaterials, J. Solid State Chem., 183, 2010, 1878–1883); Liu, YY et al. (Preparation, electronic structure, and photocatalytic properties of Bi ₂ O ₂ CO ₃ nanosheet, Appl. Surf. Sci., 257, 2010, 172–175); Zheng et al. (Synthetic Bi ₂ O ₂ CO ₃ nanostructures: Novel photocatalyst with controlled special surface exposed, Journal of Molecular Catalysis A: Chemical, 2010, 317 (1-2), 34-40); Liu, SQ et al. (The effects of citrate ion on morphology and photocatalytic activity of flower-like Bi ₂ O ₂ CO ₃ , Ceram. Int., 40, 2014, 2343–2348); or Chen, R. et al . (Bismuth subcarbonate nanoparticles fabricated by water-in-oil microemulsion-assisted hydrothermal process exhibit anti-Helicobacterpylori properties, Mater. Res. Bull., 45, 2010, 654–658).

The synthesis of particles by electrochemical route is notably described in the article by Hu, Y. et al. (Simple hydrolysis route to synthesize Bi ₂ O ₂ CO ₃ nanoplate from Bi nanopowder and its photocatalytic application, Materials Letters, 170, 2016, 72–75).

The synthesis of particles by co-precipitation is notably described in the article by Chen, XY et al. (Controlled synthesis of bismuth oxo nanoscalecrystals (BiOCl, Bi ₁₂ O ₁₇ Cl ₂ , α-Bi ₂ O ₃ , and (BiO) ₂ CO ₃ ) by solution-phase methods, J. Solid State Chem., 180, 2007, 2510–2516).

The synthesis of particles by reflux is notably described in the article by Chen et al. (Fabrication of bismuth subcarbonate nanotube arrays from bismuth citrate, Chem. Commun., 2006, 2265–2267).

According to a preferred embodiment, the bismuth oxycarbonate particles required according to the invention are obtained solvothermally, for example according to the method described by Cheng et al. , or at reflux, for example according to the method described by Chen et al..

According to a preferred embodiment, the bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, required according to the invention are obtained by a preparation process using one or more bismuth (III) complexes, one or more carbonating agents, one or more polyols and optionally one or more polar solvents, distinct from the polyols.

When the particles used according to the invention are doped, one or more additional reagents including doping elements may be added.

In particular, the bismuth(III) complex(es) is(are) chosen from bismuth nitrate and its hydrated forms, bismuth citrate and its hydrated forms, bismuth sulfate and its hydrated forms and bismuth chloride and its hydrated forms.

Bismuth(III) complex(es) can also be obtained from bismuth minerals, such as elemental bismuth and/or bismuth oxide and/or bismuth sulfide.

Preferably, the bismuth(III) complex(es) is(are) bismuth(III) nitrate and its hydrated forms of formula Bi( _NO3 ) ₃ · xH2O , and preferably is bismuth nitrate pentahydrate of formula Bi( _NO3 ) ₃ · _{5H2O .}

In particular, the carbonating agent(s) is (are) selected from Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Rb ₂ CO ₃ , Cs ₂ CO ₃ , (NH ₄ ) ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , RbHCO ₃ , CsHCO ₃ , (NH ₄ ) HCO ₃ , urea (NH ₂ ) ₂ CO and urea derivatives, CO ₂ , preferably from Na ₂ CO ₃ , K ₂ CO ₃ , (NH ₂ ) ₂ CO, (NH ₄ ) ₂ CO ₃ , and more preferably from (NH ₂ ) ₂ CO and/or (NH ₄ ) ₂ CO ₃ .

Polyols are compounds having several hydroxyl functions. They can in particular be chosen from glycols, in particular ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol; short or long polymers of glycols, for example polyethylene glycol, polypropylene glycol, polybutylene glycol; glycerol and its derivatives; or for example sugars, in particular glucose, fructose, sucrose, xylitol, mannitol, such as D-mannitol, sorbitol or maltitol.

According to one embodiment, the bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, required according to the invention are obtained by a preparation process using a polyol or a mixture of polyols.

According to a first embodiment variant, the polyol(s) may also be used as a solvent. The bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, may then be obtained for example according to the process described below.

A solution A is formed from the dissolution of the bismuth(III) complex, preferably at a concentration of 0.001 to 0.5 M, in the polyol or polyol mixture. A solution B is formed by the partial or complete dissolution of the carbonating agent, preferably from 1 to 100 equivalents relative to bismuth, in the polyol or polyol mixture or in a polyol or polyol mixture different from that(those) used in solution A.

In case of doping by a cation, the doping agent is preferably integrated into solution A. In case of doping by an anion, the doping agent is preferably integrated into solution B.

In case of doping with one or more cation(s) and/or one or more anion(s), the cationic doping agent(s) is/are preferably integrated into solution A and the anionic doping agent(s) is/are preferably integrated into solution B. Solution A is then added at room temperature to solution B. If the polyol or polyol mixture is not liquid at room temperature, all solids are mixed.

The resulting mixture is then heated to between 90 and 250 °C for a reaction time of between 10 minutes and 48 hours. If the desired reaction temperature is greater than or equal to the boiling point of the solvent, a solvothermal synthesis is carried out using an autoclave.

Preferably, the reaction temperature is between 95°C and 200°C and the reaction time is between 1 and 24 hours, and more preferably the reaction temperature is between 100°C and 180°C and the reaction time is between 2 and 16 hours.

The particles obtained are isolated from the reaction medium by centrifugation and washed by successive cycles of dispersion and centrifugation.

After drying under vacuum at a temperature between 40°C and 60°C, a white powder is obtained.

In the case where the polyol(s) are used as solvents, the bismuth oxycarbonate particles obtained are in the form of platelets, preferably with an average thickness e of between 2 and 15 nm, and/or in the form of tubes.

According to another embodiment variant, the polyol(s) are used solely as additives, and not as solvents. The bismuth oxycarbonate particles, as well as its solvates, such as its hydrates, can then be obtained for example according to the process described below.

A solution A is formed from the dissolution of the bismuth complex, preferably at a concentration of 0.001 to 0.5 M, and the polyol(s) preferably at a total concentration of polyols, preferably 0.01 to 5 M, in a solvent, preferably polar. A solution B is formed by the partial or complete dissolution of the carbonating agent, preferably 1 to 100 equivalents relative to the bismuth complex, in the polar solvent identical or different (miscible with the solvent of A) from that of solution A, preferably identical.

In case of doping by a cation, the doping agent is preferably integrated into solution A. In case of doping by an anion, the doping agent is preferably integrated into solution B.

In the case of doping by one or more cation(s) and/or by one or more anion(s), the cationic doping agent(s) is/are preferably integrated into solution A and the anionic doping agent(s) is/are preferably integrated into solution B.

Solution A is then added at room temperature to solution B. The resulting mixture is then heated between 90 °C and 250 °C for 10 minutes to 48 hours. If the desired reaction temperature is greater than or equal to the boiling point of the solvent, a solvothermal synthesis is carried out using an autoclave.

Preferably, the reaction temperature is between 90°C and 150°C and the reaction time is between 4 and 16 hours.

The particles obtained are isolated from the reaction medium by centrifugation and washed by successive cycles of dispersion and centrifugation.

After drying under vacuum at a temperature between 40°C and 60°C, a white powder is obtained.

When the polyol(s) are used solely as additives, they may in particular be chosen from ethylene glycol, propylene glycol, glycerol and/or a sugar, preferably a sugar, more preferably D-mannitol.

According to this variant, the synthesis process further uses a solvent distinct from the polyols, or a mixture of solvents distinct from the polyols. In particular, the solvent or the mixture of solvents is chosen from polar solvents, preferably from polar and protic solvents, such as water; C ₁ -C ₆ alcohols such as ethanol or isopropanol; and mixtures thereof, and even more preferably the solvent is water.

In particular, when the polyol(s) are chosen solely as additives and water as solvent, the particles of bismuth oxycarbonate, as well as its solvates, such as its hydrates, obtained are preferably in the form of platelets and/or in the form of rods.

Inorganic compound b)

The composite material according to the invention comprises at least one inorganic compound b) of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which:

- y is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably y is less than 10, more preferably less than 5, and even more preferably y denotes 1 or 2 or 3;

- z is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably z is less than 10, more preferably less than 5;

- t is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably t is less than 10, more preferably t is less than 5;

- M is a metal, an alkaline earth metal or a metalloid, preferably chosen from silicon Si, titanium Ti, iron Fe, zinc Zn, niobium Nb, tantalum Ta, cerium Ce, manganese Mn, bismuth Bi, tungsten W, aluminum Al, copper Cu and indium In, more preferably chosen from silicon Si, iron Fe, zinc Zn, niobium Nb, tantalum Ta, cerium Ce, manganese Mn, bismuth Bi, tungsten W, aluminum Al, copper Cu and indium In, particularly chosen from silicon Si, iron Fe, zinc Zn, niobium Nb, tantalum Ta, cerium Ce, manganese Mn, bismuth Bi, aluminum Al, copper Cu and indium In, better still M denotes Si or Al;

- v denotes the degree of oxidation of M and is a number between 1 and 8, preferably v is less than or equal to 6, and more preferably less than or equal to 4;

- w is an integer or fractional number ranging from 0 to 20;

- p is an integer ranging from 1 to 5, preferably p is less than or equal to 3, more preferably less than or equal to 2, even more preferably equal to 1;

- q is an integer ranging from 1 to 5, preferably q is less than or equal to 2, more preferably q is equal to 1; and

- for each inorganic compound: .

The term "inorganic oxides" means amorphous or crystalline forms, hydrated or non-hydrated, of oxides or hydroxides or oxyhydroxides of alkali or alkaline earth metals, in particular sodium, potassium, magnesium and calcium, or of transition metals, in particular titanium, aluminium, manganese, iron, copper, niobium and tantalum, in particular aluminium, manganese, iron, copper, niobium and tantalum or lanthanides, in particular cerium, or of poor metals, in particular zinc, indium and bismuth.

Inorganic oxides can also refer to amorphous or crystalline forms, hydrated or non-hydrated, of oxides or hydroxides or oxy-hydroxides of metalloids. In particular, the inorganic oxides in accordance with the invention may be amorphous or crystalline forms, hydrated or non-hydrated, of silicon oxides or hydroxides or oxy-hydroxides such as silica SiO ₂ , clays such as kaolinite, montmorillonite, illite, or hectorite, lithium and/or sodium and/or potassium and/or calcium and/or magnesium and/or aluminum and/or titanium and/or iron and/or zinc and/or bismuth silicates, aluminum and/or calcium and/or magnesium and/or sodium and/or titanium and/or iron and/or zinc and/or bismuth borosilicates.

As metal oxides [(M ^(v) _y ) _p O _z (OH) _t ] _q (H₂O) _w , we can cite the hydrated or non-hydrated forms of Al₂O₃, Al(OH)₃, SiO₂, TiO₂, MnO, MnO₂, FeO(OH), Fe₃O₄, Fe₂O₃, Cu(OH)₂, Cu₂O, CuO, Zn(OH)₂, ZnO, Nb₂O₅, In(OH)₃, In₂O₃, This₂O₃, CeO₂, Your₂O₅, WO₃, Bi₂O₃, as well as their mixtures. More particularly as metal oxides [(M ^(v) _y ) _p O _z (OH) _t ] _q (H₂O) _w , we can cite the hydrated or non-hydrated forms of Al₂O₃such as Al(OH)₃, SiO₂, MnO, MnO₂, FeO(OH), Fe₃O₄, Fe₂O₃, Cu(OH)₂, Cu₂O, CuO, Zn(OH)₂, ZnO, Nb₂O₅, In(OH)₃, In₂O₃, This₂O₃, CeO₂, Your₂O₅, WO₃, Bi₂O₃, as well as their mixtures.

More particularly, as metal oxides [(M ^(v) _y ) _p O _z (OH) _t ] _q (H₂O) _w , we can cite the hydrated or non-hydrated forms of Al₂O₃such as Al(OH)₃, SiO₂, MnO, MnO₂, FeO(OH), Fe₃O₄, Fe₂O₃, Cu(OH)₂, Cu₂O, CuO, Zn(OH)₂, ZnO, Nb₂O₅, In(OH)₃, In₂O₃, This₂O₃, CeO₂, Your₂O₅, Bi₂O₃, as well as their mixtures.

Preferably, the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ , TiO ₂ , Fe ₂ O ₃ , ZnO, Nb ₂ O ₅ , In ₂ O ₃ , CeO ₂ , Bi ₂ O ₃ and their mixtures will be used, more preferably the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ , TiO ₂ , Fe ₂ O ₃ , ZnO and their mixtures, and even more preferably the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ and their mixtures.

More particularly, the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ , ZnO, Nb ₂ O ₅ , In ₂ O ₃ , CeO ₂ , Bi ₂ O ₃ and their mixtures will be used, more preferably the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ , Fe ₂ O ₃ , ZnO and their mixtures, and even more preferably the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ and their mixtures.

Preferably [(M ^(v) _{y ) pOz} (OH) _t ] _q ( _H2O ) _w is different of TiO ₂

According to a first particular embodiment, q is equal to 1 and p is equal to 1.

According to this embodiment, preferably M denotes aluminum Al, silicon Si, titanium Ti, manganese Mn, iron Fe, copper Cu, zinc Zn, niobium Nb, indium In, cerium Ce, tantalum Ta, tungsten W and bismuth Bi.

Preferably, M denotes Si, Ti, Fe, Zn or Bi, and more preferably Si, Ti, Zn, better still Si.

According to one embodiment M is different from Ti.

Preferably, M denotes Si, Fe, Zn or Bi, and more preferably Si, Zn, better still Si.

According to a second embodiment, q is equal to 1 and p is greater than 1.

According to this embodiment, q is equal to 1 and preferably p is greater than 1 and less than or equal to 3, more preferably p is equal to 2.

Preferably, at least one of the M is chosen from aluminum Al, silicon Si, titanium Ti, manganese Mn, iron Fe, copper Cu, zinc Zn, niobium Nb, indium In, cerium Ce, tantalum Ta, tungsten W, and bismuth Bi, and, more preferably chosen from Si, Ti, Fe, Zn, Bi, and even more preferably chosen from Si, Ti and Zn.

More particularly, at least one of the M is chosen from aluminum Al, silicon Si, manganese Mn, iron Fe, copper Cu, zinc Zn, niobium Nb, indium In, cerium Ce, tantalum Ta, tungsten W, and bismuth Bi, and, more preferably chosen from Si, Fe, Zn, Bi, and even more preferably chosen from Si, and Zn

Preferably, at least one of the M is an alkali or alkaline earth metal, preferably chosen from Na, K, Mg, Ca.

According to another embodiment, q is greater than 1, and preferably q is equal to 2.

According to this embodiment, at least one of the M is chosen from aluminum Al, silicon Si, titanium Ti, manganese Mn, iron Fe, copper Cu, zinc Zn, niobium Nb, indium In, cerium Ce, tantalum Ta, tungsten W and bismuth Bi.

Preferably, M denotes Si, Ti, Fe, Zn or Bi, and more preferably Si, Ti, Zn, compounds b) being able to additionally contain at least one alkali or alkaline-earth metal preferably chosen from Na, K, Mg and Ca.

Composite material preparation process

The composite materials according to the invention can in particular be obtained according to the preparation methods described below.

In particular, the composite materials according to the invention as defined above can be obtained in one or more stages.

In particular, the composite materials according to the invention can be obtained from pre-formed bismuth oxycarbonate particles a), in particular obtained by the processes as described above.

According to a particular embodiment, the process for preparing the composite materials according to the invention uses pre-formed bismuth oxycarbonate particles a) and may comprise one or more separation and/or heat treatment steps.

In particular, such a method for preparing composite materials according to the invention implements:

- at least one particle of bismuth oxycarbonate a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm;

- optionally one or more precursors intended to form the compound(s) b) as described above;

- possibly one or more additives; and

- possibly one or more solvents.

According to a particular embodiment, the process for preparing composite materials according to the invention uses pre-formed particles consisting of one or more inorganic compounds b) and may comprise one or more separation and/or heat treatment steps.

In particular, such a method for preparing composite materials according to the invention implements:

- at least one precursor of bismuth oxycarbonate particles a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm;

- at least one carbonating agent;

- possibly one or more additives; and

- possibly one or more solvents.

The precursors of bismuth oxycarbonate particles a) according to the invention, as well as its solvates, such as its hydrates, are in particular chosen from soluble bismuth (III) complexes, more particularly bismuth nitrate and its hydrated forms, bismuth citrate and its hydrated forms, bismuth sulfate and its hydrated forms, bismuth chloride and its hydrated forms.

The bismuth(III) complex(es) may in particular be obtained from bismuth minerals such as elemental bismuth and/or bismuth oxide and/or bismuth sulfide.

The carbonating agent(s) are in particular chosen from Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Rb ₂ CO ₃ , Cs ₂ CO ₃ , (NH ₄ ) ₂ CO ₃ , LiHCO ₃ , NaHCO ₃ , KHCO ₃ , RbHCO ₃ , CsHCO ₃ , (NH ₄ )HCO ₃ , urea (NH ₂ ) ₂ CO and urea derivatives, CO ₂ .

The organic or inorganic precursors, hydrated or not, of the compounds containing at least one element M are in particular chosen from solubilized oxides such as sodium aluminates or silicates, halides and their hydrated versions, nitrates and their hydrated versions, carbonates and their hydrated versions, sulfonates and their hydrated versions, sulfates and their hydrated versions, phosphates and their hydrated versions, and/or organometallic precursors and their hydrated versions, in particular alkoxides and their hydrated versions, carboxylates and their hydrated versions, lactates and their hydrated versions, citrates and their hydrated versions.

According to a particular embodiment, the method for preparing composite materials according to the invention uses at least one additive.

In particular, any additives used depend on the synthesis process and may be chosen from acids, bases, oxidants, reducers and/or any reagent necessary for the precipitation of the species and/or their adhesion.

In particular, the additive(s) may be chosen from acids, in particular mineral acids, such as hydrochloric acid or sulfuric acid, and bases, preferably mineral bases, such as sodium hydroxide or potassium hydroxide.

In particular, the additives may in particular be one or more organic and/or inorganic additives necessary for the reactions making it possible to obtain the inorganic compound(s) b), and may therefore in particular be oxidizing precursors, in particular air, hydrogen peroxide, peroxides and their hydrated versions.

Possible additives necessary for precipitation and/or adhesion may be surfactants such as sodium dodecyl sulfate and sugars such as mannitol or glucose.

According to a particular embodiment, the process for preparing composite materials according to the invention uses at least one solvent.

The choice of solvent(s) may in particular depend on the precursor(s) and additive(s) used in the process.

In particular, the solvent(s) may be chosen from polar and/or apolar, protic and/or aprotic solvents.

Preferably, the solvent used is a polar and protic solvent, in particular chosen from water, alcohols, polyols and their mixtures.

Preferably, the solvent used is water.

According to a particular embodiment, the process for preparing the composite materials according to the invention may comprise one or more separation steps, for example by filtration and/or centrifugation.

According to a particular embodiment, the method for preparing the composite materials according to the invention may comprise one or more heat treatment steps, carried out with or without solvent, under an inert atmosphere or not, for example at temperatures varying from 50°C to 1200°C, in particular to remove the solvents and/or other volatile residual molecules from the materials and/or to induce a transformation, such as dehydration or crystallization.

According to a preferred embodiment, the preparation method according to the invention uses pre-formed bismuth oxycarbonate particles a), to form the core of said composite material.

According to a preferred embodiment, the preparation method according to the invention uses a single inorganic compound b) to constitute the shell of the composite particles, and preferably the inorganic compound b) is chosen from silica and titanium dioxide, and more preferably is silica.

According to these embodiments, the composite materials can be obtained by precipitation on the core:
- one or more silicon tetraalkoxides, preferably _C2 - _C4 , such as tetraethylorthosilicate or tetrapropylorthosilicate, in particular according to a process derived from the so-called Stöber method (Controlled Growth of Monodisperse Silica Spheres in the Micron Size Range. J. Colloid Interface Sci . 1968, 26 (1), 62–69);
- or sodium silicate (Brinker, CJ; Scherer, GW Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing ; Elsevier, 1990) in aqueous medium by analogy with the process described by Pfluecker et al. (Nanoparticulate UV Protectant With Silicon Dioxide Coating. US 8758501 B2, 2014) on titanium dioxide;
- and/or _C2 - _C4 titanium alkoxides, and in particular titanium tetraisopropoxide.

According to another preferred embodiment, the preparation method according to the invention uses pre-formed particles of at least one inorganic compound b), preferably silica, to form the core of said composite material, and the shell is made of bismuth oxycarbonate a), as well as its solvates, such as its hydrates.

According to this embodiment, the composite materials can in particular be obtained by precipitation of bismuth nitrate pentahydrate using ammonium carbonate on the core of inorganic compound(s) b).

According to a particular embodiment, the present invention aims at a process for preparing composite materials as defined above comprising the steps consisting of:

(i) having a dispersion of bismuth oxycarbonate particles a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, in at least one solvent, in particular in an amount ranging from 0.05 g/L to 500 g/L;

(ii) having an aqueous solution of sodium silicate b), in particular in a Si/Bi molar ratio of between 0.001 and 10, preferably of between 0.01 and 2, and even more preferably of between 0.1 and 1;

(iii) bringing together said dispersion (i) and said solution (ii) to form the composite material;

(iv) insulate said composite material.

In particular, the solvent(s) of step (i) is chosen from polar and protic solvents, more preferably from water, alcohols, polyols and their mixtures, and even more preferably is water.

According to a particular embodiment, the medium of the dispersion (i) can be heated to reflux, preferably to a temperature less than or equal to 100°C.

According to a particular embodiment, solution (ii) can be heated to reflux, preferably to a temperature of 100°C, before the mixing of step (iii).

According to a particular embodiment, the aqueous sodium silicate solution b) is in an amount ranging from 0.05 g/L to 500 g/L.

According to a particular embodiment, the pH in step (iii) is adjusted to a pH ranging from 3 to 11, in particular from 5 to 8, preferably from 6 to 7, in particular to form the silica.

According to a particular embodiment, step (iii) is carried out for a period ranging from 15 minutes to 48 hours, preferably from 1 hour to 24 hours, and more preferably from 2 hours to 8 hours.

According to a particular embodiment, a cooling step can be carried out between steps (iii) and (iv).

According to a particular embodiment, step (iv) can be carried out by centrifugation.

According to a particular embodiment, step (iv) is followed by a washing step, in particular by successive cycles, and optionally drying in an oven, for example at a temperature ranging from 40°C to 100°C and optionally under vacuum (pressure less than 100 mbar).

According to a particular embodiment, the present invention aims at a process for preparing composite materials as defined above comprising the steps consisting of:

(1) having a dispersion of bismuth oxycarbonate particles a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, in at least one solvent, in particular in an amount ranging from 0.05 g/L to 500 g/L;

(1’) adding a basic aqueous solution, preferably aqueous ammonia to said dispersion (1);

(2) have a solution of at least one silicon tetraalkoxide b);

(3) bringing together said dispersion (1’) and said solution (2) to form the composite material;

(4) insulate said composite material.

In particular, the solvent(s) of step (1) is chosen from polar and protic solvents, more preferably from alcohols, and even more preferably is an alcohol corresponding to the alkoxide group of silicon tetraalkoxide b) or corresponding to one of the alkoxide groups in the case of use of a mixture of silicon tetraalkoxides b).

According to a particular embodiment, the dispersion medium (1) can be heated until the medium refluxes, preferably at a temperature between 50°C and 70°C.

According to a particular embodiment, the medium is maintained at this temperature throughout the duration of the reaction.

According to a particular embodiment, the molar ratio in step (3) ammonia/silicon varies from 0.005 to 50, more preferably from 0.1 to 5.

According to a particular embodiment, the molar ratio in step (3) Si/Bi varies from 0.001 to 2, more preferably from 0.01 to 1.5, and even more preferably from 0.1 to 1.

According to a particular embodiment, step (3) is carried out for a period ranging from 15 minutes to 48 hours, preferably from 30 minutes to 24 hours and more preferably from 1 hour to 8 hours.

According to a particular embodiment, a cooling step can be carried out between steps (3) and (4).

According to a particular embodiment, step (4) can be carried out by centrifugation.

According to a particular embodiment, step (4) is followed by a washing step, in particular by successive cycles, and optionally drying in an oven, for example at a temperature ranging from 40°C to 100°C and optionally under vacuum (pressure less than 100 mbar).

According to a particular embodiment, the present invention aims at a process for preparing composite materials as defined above comprising the steps consisting of:

(a) having a dispersion of bismuth oxycarbonate particles a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, in at least one solvent, in particular in an amount ranging from 0.05 g/L to 500 g/L;

(a’) optionally adding a basic aqueous solution, preferably sodium hydroxide, preferably with a pH ranging from 8 to 13, and more preferably from 9 to 12, to said dispersion (a);

(b) having a solution of at least one titanium tetraalkoxide b), optionally in at least one solvent, in particular in a Ti/Bi molar ratio varying from 0.001 to 2, more preferably from 0.01 to 1.5, and more preferably from 0.1 to 1;

(c) bringing together said dispersion (a’) and said solution (b) to form the composite material;

(d) insulating said composite material.

In particular, the solvent(s) of step (a) and (b) may be identical or different, preferably identical, and preferably chosen from polar and protic solvents, more preferably from alcohols, and even more preferably is an alcohol corresponding to the alkoxide group of titanium tetraalkoxide b) or corresponding to one of the alkoxide groups in the case of use of a mixture of titanium tetraalkoxides b).

According to a particular embodiment, the medium of the dispersion (a) can be heated until the medium refluxes, preferably at a temperature between 20°C and 50°C.

According to a particular embodiment, the medium is maintained at this temperature throughout the duration of the reaction.

According to a particular embodiment, the solution of at least one titanium tetraalkoxide b) is in an amount ranging from 0.05 g/L to 500 g/L.

According to a particular embodiment, step (c) is carried out for a period ranging from 5 minutes to 48 hours, preferably from 15 minutes to 24 hours and more preferably from 30 minutes to 8 hours.

According to a particular embodiment, a cooling step can be carried out between steps (c) and (d).

According to a particular embodiment, step (d) can be carried out by centrifugation.

According to a particular embodiment, step (d) is followed by a washing step, in particular by successive cycles, and optionally drying in an oven, for example at a temperature ranging from 40°C to 100°C and optionally under vacuum (pressure less than 100 mbar).

Cosmetic composition

The composite materials according to the invention can in particular be used in a composition, in particular in a cosmetic composition.

Thus, the present invention also relates to a composition, in particular cosmetic, comprising at least one composite material as defined above.

According to a preferred embodiment, the present invention also relates to a composition, in particular cosmetic, comprising at least:

(i) at least one composite material as defined above;

ii) at least one aqueous phase and/or at least one fatty phase; and

iii) at least one compound chosen from: 1) UV filters distinct from composite materials i); 2) coloring matters; 3) cosmetic active ingredients for the care of keratin materials; 4) surfactants; 5) thickeners; and mixtures thereof.

Said composite materials may be present in the composition, preferably cosmetic, in a content ranging from 0.5% to 70% by weight, preferably from 1% to 50% by weight, even better from 2 to 40% by weight relative to the total weight of the composition.

Aqueous phase

A composition, in particular a cosmetic composition, according to the invention may comprise at least one aqueous phase.

The aqueous phase may comprise water and optionally a water-soluble solvent.

In the present invention, the term " water-soluble solvent " means a compound which is liquid at room temperature and miscible with water (miscibility in water greater than 50% by weight at 25°C and atmospheric pressure).

The water-soluble solvents that can be used in a composition according to the invention can also be volatile.

Among the water-soluble solvents which may be used in a composition in accordance with the invention, mention may be made in particular of lower monoalcohols having from 1 to 5 carbon atoms such as ethanol and isopropanol, C ₂ -C ₃₂ polyols, C ₃ and C ₄ ketones and C ₂ -C ₄ aldehydes.

Among the water-soluble solvents that can be used in a composition in accordance with the invention, mention may be made in particular of polyols. By " polyol ", it is necessary to understand, for the purposes of the present invention, any organic molecule comprising at least two free hydroxyl groups.

A polyol suitable for the invention may be a compound of alkyl type, linear, branched or cyclic, saturated or unsaturated, carrying on the alkyl chain at least two –OH functions, in particular at least three –OH functions.

The polyols advantageously suitable for the formulation of a composition according to the present invention are those having in particular from 2 to 32 carbon atoms, preferably 3 to 16 carbon atoms.

Advantageously, the polyol may be chosen, for example, from pentaerythritol, trimethylolpropane, caprylyl glycol, glycerol, polyglycerols, such as glycerol oligomers such as diglycerol, polyethylene glycols, polypropylene glycols, and mixtures thereof.

Fat phase

A composition, in particular a cosmetic composition, according to the invention may further comprise at least one fatty phase, in particular an oily phase.

For the purposes of the invention, the term “fatty phase” means a phase comprising at least one fatty substance and all of the liposoluble and lipophilic ingredients used for the formulation of the compositions of the invention.

Preferably, the fatty phase comprises at least one oil, in particular a cosmetic oil.

" Oil " means a non-aqueous compound, immiscible with water, liquid at room temperature (25°C) and atmospheric pressure (760 mm Hg).

The fatty phase may comprise at least one volatile or non-volatile hydrocarbon oil and/or a fatty substance.

As non-volatile hydrocarbon oils, mention may in particular be made of hydrocarbon oils of vegetable origin, synthetic ethers having from 10 to 40 carbon atoms, linear or branched hydrocarbons, of mineral or synthetic origin, synthetic esters, fatty alcohols which are liquid at room temperature with a branched and/or unsaturated carbon chain having from 12 to 26 carbon atoms, higher fatty acids in C ₁₂ -C ₂₂ , carbonates, and mixtures thereof.

Examples of volatile hydrocarbon oils include hydrocarbon oils with 8 to 16 carbon atoms.

Non-volatile silicone oils may be chosen in particular from non-volatile polydimethylsiloxanes (PDMS) and phenylated silicones. As volatile silicone oils, examples that may be mentioned are volatile linear or cyclic silicone oils.

Fluorinated volatile oils, such as nonafluoromethoxybutane, nonafluoromethoxybutane, decafluoropentane, tetradecafluorohexane, dodecafluoropentane and mixtures thereof, may also be used.

The oily phase may further comprise, mixed with or dissolved in the oil, other fatty substances. Another fatty substance that may be present in the oily phase may be, for example, a fatty acid, a wax, a gum, a pasty compound, or mixtures thereof.

1) Additional UV filters

According to a particular embodiment, a composition according to the invention comprises 1) at least one complementary UV filter distinct from the composite materials required according to the invention and defined above.

By “ complementary UV filter distinct from composite materials ” is meant, for the purposes of the present invention, any UV filter whose chemical nature differs from that of the composite materials required according to the invention and defined above.

The composite materials according to the invention can therefore be used alone or in combination with 1) other UV filters, in particular chosen from organic and/or inorganic UV filters.

Thus, the cosmetic composition may also contain one or more complementary UV filters chosen from hydrophilic, lipophilic or insoluble organic UV filters and/or mineral UV filters, different from the composite materials according to the invention.

By " hydrophilic UV filter " is meant any organic or inorganic cosmetic or dermatological compound filtering UV radiation capable of being completely dissolved in the molecular state in a liquid aqueous phase or of being in colloidal suspension (for example in micellar form) in a liquid aqueous phase.

By " lipophilic UV filter " is meant any organic or inorganic cosmetic or dermatological compound filtering UV radiation capable of being completely dissolved in the molecular state in a liquid fatty phase or of being in colloidal suspension (for example in micellar form) in a liquid fatty phase.

By " insoluble UV filter " is meant any organic or inorganic cosmetic or dermatological compound filtering UV radiation having a solubility in water of less than 0.5% by weight and a solubility of less than 0.5% by weight in most organic solvents such as paraffin oil, fatty alcohol benzoates and fatty acid triglycerides, for example Miglyol 812 ^® . This solubility, achieved at 70 °C, is defined as the quantity of product in solution in the solvent at equilibrium with an excess of suspended solid after returning to room temperature. It can easily be evaluated in the laboratory.

Complementary organic UV filters are chosen in particular from:

- cinnamic compounds, in particular Ethylhexyl Methoxycinnamate,

- anthranilate compounds, in particular Menthyl anthranilate,

- salicylic compounds, in particular Homosalate and Ethylhexyl Salicylate,

- dibenzoylmethane compounds, in particular Butyl Methoxydibenzoylmethane,

- benzylidene camphor compounds, in particular 3-Benzylidene camphor, 4-Methylbenzylidene camphor, Benzylidene Camphor Sulfonic Acid and Terephthalylidene Dicamphor Sulfonic Acid,

- benzophenone compounds, in particular oxybenzone and n-hexyl 2-(4-diethylamino-2-hydroxybenzoyl)-benzoate,

- β,β-diphenylacrylate compounds, in particular octocrylene,

- triazine compounds, in particular Phenylene Bis-Diphenyl triazine, Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine, Ethylhexyl Triazone and Diethylhexyl Butamido Triazone,

- benzotriazole compounds, in particular Drometrizole Trisiloxane,

- benzalmalonate compounds, in particular those cited in US patent 5624663, in particular Polysilicone-15,

- benzimidazole derivatives, in particular Phenylbenzimidazole Sulfonic Acid,

- imidazoline compounds, in particular Ethylhexyl Dimethoxybenzylidene Dioxoimidazoline Propionate,

- bis-benzoazolyl compounds, as described in patents EP 0669323 and US 2463264, in particular Disodium Phenyl Dibenzimidazole Tetra-sulfonate,

- para-aminobenzoic compounds, in particular PABA, Ethylhexyl Dimethyl PABA and PEG-25 PABA,

- methylene bis-(hydroxyphenyl benzotriazole) compounds, as described in applications US 5237071, US 5166355, GB 2303549, DE 19726184 and EP 0893119, in particular Methylene bis-Benzotriazolyl Tetramethylbutylphenol,

- benzoxazole compounds, as described in patent applications EP 0832642, EP 1027883, EP 1300137 and DE 10162844, in particular 2,4-bis-[5-1(dimethylpropyl)benzoxazol-2-yl-(4-phenyl)-imino]-6-(2-ethylhexyl)-imino-1,3,5-triazine,

- filter polymers and filter silicones, such as those described in particular in application WO 93/04665,

- dimers derived from α-alkylstyrene, such as those described in patent application DE 19855649,

- 4,4-diarylbutadienes compounds, as described in applications EP 0967200, DE 19746654, DE 19755649, EP 1008586, EP 1133980 and EP 0133981, in particular 1,1-dicarboxy(2,2’-dimethyl-propyl)-4,4-diphenylbutadiene,

- their mixtures.

Inorganic UV filters are generally mineral UV filters, particularly chosen from metal oxides.

The metal oxides may be chosen in particular from titanium, zinc, iron, zirconium, cerium oxides, and their mixtures.

Metal oxide particles can be coated or uncoated.

The coated particles are more particularly titanium oxides coated with silica, silica and iron oxide, silica and alumina, alumina, alumina and aluminum stearate, silica, alumina and alginic acid, alumina and aluminum laurate, iron oxide and iron stearate, zinc oxide and zinc stearate, silica and alumina and treated with a silicone, silica, alumina, aluminum stearate and treated with a silicone, silica and treated with a silicone, alumina and treated with a silicone, triethanolamine, stearic acid, sodium hexametaphosphate, or TiO ₂ treated with octyl trimethyl silane, TiO ₂ treated with a polydimethylsiloxane, polydimethylhydrogensiloxane-treated anatase/rutile TiO ₂ , TiO ₂ coated with triethylhexanoin, aluminum stearate and alumina, TiO ₂ coated with aluminum stearate, alumina and silicone, TiO ₂ coated with lauroyl lysine, or TiO ₂ coated with C _9-15 fluoroalcohol phosphate and aluminum hydroxide.

Metal oxides can optionally be doped.

In this respect, we can cite _TiO2 particles doped with at least one transition metal such as iron, zinc, manganese, and more particularly manganese.

The doped particles may be in the form of a dispersion, preferably an oily dispersion. The oil present in the oily dispersion is preferably chosen from triglycerides, including those of capric/caprylic acids. The oily dispersion of titanium oxide particles may additionally comprise one or more dispersing agents, for example a sorbitan ester or a polyoxyalkylenated fatty acid and glycerol ester. More particularly, mention may be made of the oily dispersion of manganese-doped TiO ₂ particles in capric/caprylic acid triglyceride in the presence of tri-PPG-3 myristylether citrate and polyglyceryl-3-polyricinoleate and sorbitan isostearate.

Mention may also be made of mixtures of metal oxides, in particular titanium dioxide and cerium dioxide, including the equal-weight mixture of titanium dioxide and cerium dioxide coated with silica, as well as the mixture of titanium dioxide and zinc dioxide coated with alumina, silica and silicone or coated with alumina, silica and glycerin.

2) Coloring materials

According to a particular embodiment, a composition according to the invention comprises 2) at least one coloring material.

Generally speaking, a " coloring material " is intended to designate any compound capable of coloring a composition, that is to say which absorbs in the visible spectrum, in particular so as to appear to the human eye as a color such as yellow, orange, red, violet, blue or green.

Preferably, a composition according to the invention comprises at least one pigment.

By " pigments " is meant white or colored particles, mineral or organic, insoluble in liquid hydrophilic and lipophilic phases, intended to color and/or opacify the composition containing them, and different from the composite materials according to the invention. More particularly, the pigments are slightly or not at all soluble in hydroalcoholic media.

The pigments that can be used are in particular chosen from organic and/or mineral pigments known in the art, in particular those described in Kirk-Othmer's Encyclopedia of Chemical Technology and in Ullmann's Encyclopedia of Industrial Chemistry (Ullmann's Encyclopedia of Industrial Chemistry "Pigment organics", 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a20 371 and ibid, "Pigments, Inorganic, 1. General” 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim10.1002/14356007.a20_243.pub3).

These pigments can be in the form of powder or pigment paste. They can be coated or uncoated.

The pigments can for example be chosen from mineral pigments, organic pigments, lakes, special effect pigments such as mother-of-pearl or glitter, and mixtures thereof.

The pigment may be a mineral pigment. By mineral pigment is meant any pigment that meets the definition of the Ullmann encyclopedia in the inorganic pigment chapter. Among the mineral pigments useful in the present invention, mention may be made of iron or chromium oxides, manganese violet, ultramarine blue, chromium hydrate, ferric blue and titanium oxide.

The pigment may be an organic pigment.

By organic pigment is meant any pigment that meets the definition of the Ullmann encyclopedia in the organic pigment chapter.

The organic pigment may in particular be chosen from nitroso, nitro, azo, xanthene, quinoline, anthraquinone, phthalocyanine, metal complex type compounds, isoindolinone, isoindoline, quinacridone, perinone, perylene, diketopyrrolopyrrole, thioindigo, dioxazine, triphenylmethane, quinophthalone.

Preferably, the pigment(s) suitable for the invention are chosen from carbon black, iron oxides, in particular red, brown or black, micas coated with iron oxide, triarylmethane pigments, in particular blue and violet, such as BLUE 1 LAKE, azo pigments, in particular red, such as D&C RED 7, alkali metal salts of lithol red, such as the calcium salt of lithol red B, more preferably the pigment(s) used are chosen from red iron oxides and azo pigments, in particular red, such as D&C RED 7.

The coloring matter(s) may be present in a composition according to the invention in a content ranging from 0.001 to 10% by weight, preferably from 0.005% to 5% by weight, relative to the total weight of the composition.

According to a particular embodiment of the invention, the quantity of pigments varies from 0.5% to 40%, and preferably from 1 to 20% relative to the weight of the composition of the invention comprising them.

3) Cosmetic active ingredient

According to a particular embodiment, a composition according to the invention comprises 3) at least one cosmetic active ingredient for caring for keratin materials, preferably for caring for the skin.

In particular, the cosmetic active ingredient may be at least one hydrophilic active ingredient and/or one lipophilic active ingredient, preferably hydrophilic.

The term “ hydrophilic active ” means a water-soluble or water-dispersible active agent capable of forming hydrogen bonds.

Cosmetic active ingredients include, for example, moisturizing agents, depigmenting agents, desquamating agents, humectants, anti-aging agents, mattifying agents, healing agents, antibacterial agents, vitamins and their derivatives or precursors, antioxidant compounds, anti-radical agents, anti-polluting agents, self-tanning agents, anti-glycation agents, soothing agents, deodorant agents, essential oils, NO-synthase inhibitors, agents stimulating the synthesis of dermal or epidermal macromolecules and/or preventing their degradation, agents stimulating the proliferation of fibroblasts, agents stimulating the proliferation of keratinocytes, myorelaxant agents, refreshing agents, tensing agents, depigmenting agents, pro-pigmenting agents, keratolytic agents, slimming agents, agents acting on the energy metabolism of cells, agents insect repellents, antagonists of substances P or CRGP, anti-hair loss agents, and mixtures thereof

The asset(s) may in particular be chosen from:

- vitamins and their derivatives, in particular their esters, such as niacinamide (3-pyridinecarboxamide) nicotinamide (vitamin B3), tocopherol (vitamin E) and its esters (such as tocopheryl acetate), ascorbic acid and its derivatives (vitamin C), retinol (Vitamin A),

- humectants or moisturizers such as urea, hydroxyureas, glycerol, polyglycerols, glycerolglucoside, diglycerolglucoside, polyglycerylglucosides, xylitylglycoside and plant extracts (in particular tea, mint, orchid, soya, aloe vera, honey, and in particular glycerol;

- C-glycoside compounds, and preferably hydroxypropyl tetrahydropyrantiol (INCI name) (or proxylane);

- antioxidant compounds;

- anti-aging active ingredients, such as hyaluronic acid compounds, and in particular sodium hyaluronate, salicylic acid compounds and in particular n-octanoyl-5-salycilic acid (capryloyl salicylic acid), adenosine, and the sodium salt of 3-hydroxy-2-pentylcyclopentyl)acetic acid;

- keratolytic agents such as lactic acid or glycolic acid; and

- their mixtures.

Such active ingredients may be present in a composition according to the invention in a content ranging from 0.05% to 10% by weight, preferably from 1.0% to 8.0% by weight, relative to the total weight of the composition.

4) Surfactant

According to a particular embodiment, a composition according to the invention comprises 4) at least one surfactant.

The surfactants may be selected from nonionic, anionic, cationic, amphoteric surfactants, and mixtures thereof. Reference may be made to the document “Encyclopedia of Chemical Technology, KIRK-OTHMER”, volume 22, p. 333-432, 3rd edition, 1979, WILEY, for the definition of the emulsifying properties and functions of surfactants, in particular p. 347-377 of this reference, for anionic, amphoteric and nonionic surfactants.

Examples of amphoteric surfactants suitable for the invention are in particular chosen from betaines, preferably chosen from alkyl betaines, in particular lauryl betaine; N-alkylamido betaines and their derivatives, in particular cocamidopropyl betaine, lauramidopropyl betaine and N-carboxyethoxyethyl N-cocoylamidoethyl aminoacetate N-disodium; sultaines, in particular cocoyl amidopropylhydroxy sultaine; and mixtures thereof.

The nonionic surfactants may be chosen in particular from poly(ethylene oxide) alkyl- and polyalkyl-esters, oxyalkylenated alcohols, poly(ethylene oxide) alkyl- and polyalkyl-ethers, polyoxyethylenated or non-polyoxyethylenated sorbitan alkyl- and polyalkyl-esters, polyoxyethylenated or non-polyoxyethylenated sorbitan alkyl- and polyalkyl-ethers, in particular sucrose alkyl- and polyalkyl-esters, polyoxyethylenated or non-polyoxyethylenated glycerol alkyl- and polyalkyl-ethers, polyoxyethylenated or non-polyoxyethylenated glycerol alkyl- and polyalkyl-ethers, geminal surfactants, cetyl alcohol, stearyl alcohol, and mixtures thereof.

The anionic surfactants may be chosen from alkyl ether sulfates, carboxylates, amino acid derivatives, sulfonates, isethionates, taurates, sulfosuccinates, alkylsulfoacetates, phosphates and alkylphosphates, polypeptides, metal salts of C fatty acids₁₀-C₃₀, especially in C₁₆-C₂₅, especially metal stearates and behenates and their mixtures.

The cationic surfactants may be chosen from alkylimidazolidiniums, such as isostearylethylimidonium ethosulfate, ammonium salts, such as (C _12-30 alkyl)-tri(C _1-4 alkyl)ammonium halides such as N,N,N-trimethyl-1-docosaminium chloride (or Behentrimonium chloride).

Silicone surfactants can be chosen from dimethicone copolyols or silicone elastomers.

A composition according to the invention may comprise between 0.01% and 2.0% by weight of surfactant, preferably between 0.05% and 1.5% by weight, more preferably between 0.1% and 1.0% by weight, relative to the total weight of the composition.

5) Thickener

According to a particular embodiment, a composition according to the invention comprises 5) at least one thickener, also sometimes called gelling agent or viscosity modifying agent.

Thickeners can be synthetic, natural or naturally derived, preferably natural or naturally derived.

Such thickeners may more particularly be chosen from natural polymers or polymers of natural origin, in particular of plant origin.

These gelling agents are preferably hydrophilic, that is to say soluble or dispersible in water.

Advantageously, the thickener(s) are chosen from polysaccharides, modified or native, in particular modified or unmodified starches, fructans, gellans, glucans, amylose, amylopectin, glycogen, pullulan, dextrans, celluloses and their derivatives, in particular methylcelluloses, hydroxyalkylcelluloses, ethylhydroxyethylcelluloses, and carboxymethylcelluloses, mannans, xylans, lignins, arabans, galactans, galacturonans, alginate-based compounds, chitin, chitosans, glucuronoxylans, arabinoxylans, xyloglucans, glucomannans, pectic acids and pectins, arabinogalactans, carrageenans, agars, glycosaminoglucans, gum arabic, sclerotium gum, tragacanth gum, ghatti gum, karaya gum, locust bean gum, konjac gum, galactomannans such as guar gum and their non-ionic derivatives, in particular hydroxypropyl guar, and ionic, biopolysaccharide gums of microbial origin, in particular scleroglucan or xanthan gum, mucopolysaccharides, carboxyvinyl polymers, polyacrylamides, polymers and copolymers of 2-acrylamido-2-methylpropanesulfonic acid, optionally crosslinked and/or neutralized, water-soluble or water-dispersible silicone derivatives, such as acrylic silicones, polyether silicones and cationic silicones, and mixtures thereof.

The thickener(s) may be present in a composition according to the invention in a content ranging from 0.05 to 5.0% by weight, in particular from 0.3% to 4.0% by weight, more particularly from 0.4% to 2.5% by weight, relative to the total weight of the composition.

Adjuvants

A composition according to the invention may also comprise at least one adjuvant usual in the cosmetic field chosen from perfumes, film-forming polymers, pH adjusters (acids or bases), for example citric acid, tartaric acid or oxalic acid, chelating agents, preservatives, softeners, sweeteners, anti-foaming agents, fillers, trace elements, propellants, and mixtures thereof.

Of course, the person skilled in the art will take care to choose this or these possible additional compounds and/or their quantity in such a way that the advantageous properties of a composition according to the invention are not, or not substantially, altered by the envisaged addition.

Of course, the person skilled in the art will take care to choose this or these possible complementary compounds, and/or their quantity, in such a way that the advantageous properties of the particles according to the invention are not, or not substantially, altered by the envisaged addition.

As stated above, a composition according to the invention may be cosmetic, and preferably is cosmetic.

A composition according to the invention is generally suitable for topical application to the skin and therefore generally comprises a physiologically acceptable medium, i.e. compatible with the skin.

It is preferably a cosmetically acceptable medium, that is to say which has a pleasant color, odor and feel and does not generate unacceptable discomfort, that is to say tingling, tightness, likely to dissuade the user from applying this composition.

Galenic forms of the compositions

The compositions, in particular cosmetic compositions, containing the particles according to the invention can be prepared according to techniques well known to those skilled in the art.

They can be presented in all classic galenic forms depending on the intended applications and are suitable for topical application, that is to say for application on the surface of the keratin materials considered.

Cosmetic compositions can be presented in the form of an aqueous or hydroalcoholic gel.

They can be presented in the form of an emulsion, simple or complex (O/W, W/O, O/W/O or W/O/W), such as a cream, a milk, or a cream gel.

They can also be present in anhydrous form, for example in the form of an oil.

The term " anhydrous composition " means a composition containing less than 5% by weight of water, or even less than 2% water, better still less than 1% water and in particular free of water, the water not being added during the preparation of the composition but corresponding to the residual water provided by the mixed ingredients.

Cosmetic compositions can, for example, be used as make-up products.

Cosmetic compositions may, for example, be used as a care and/or sun protection product for the face and/or body of liquid to semi-liquid consistency, and have the appearance of a white or colored cream, more or less creamy, an ointment, a milk, a gel-cream, a lotion, a serum, a paste or a mousse. It may possibly be applied to the skin in the form of an aerosol. It may also be in solid form, for example in the form of a stick.

Cosmetic compositions may be in the form of skin or semi-mucous membrane care products, such as a protective composition, cosmetic care for the face, lips, hands, feet, anatomical folds or body (for example day creams, night creams, day serums, night serums, make-up remover creams, make-up bases, protective or care body milk, after-sun milk, lotion, gel or foam for skin or scalp care, serum, mask or after-shave composition).

The composition can be applied by hand or using an applicator.

In particular, the cosmetic compositions have an SPF value greater than 5 and preferably greater than 10.

For the purposes of the invention, the term "SPF" (Sun Protection Factor) means: the sun protection factor which measures the level of protection against UV radiation. The SPF value corresponds to the ratio between the minimum time required to obtain a sunburn (erythematogenic) with a sun protection composition and the minimum time without a sun protection composition to obtain said sunburn. More specifically, the term "SPF" is defined in the article A new substrate to measure sunscreen protection factor across the ultraviolet spectrum, J. Soc. Cosmet. Chem., 40, 127-133 (May/June 1989).

The SPF (Sun Protection Factor) assessment can be performed in vitro with a Labsphere® spectrophotometer. The plate is the material on which the sunscreen composition is applied. For this protocol, poly(methyl methacrylate) (PMMA) plates have proven to be ideal.

The evaluation of the Sun Protection Factor (SPF) of the compositions can also be carried out in vivo according to the ISO 24444 protocol “Cosmetics - Sun protection test methods - In vivo determination of the sun protection factor (SPF) (2010)”.

By "UVAPF" is meant: the index characterizing the protection against UVA radiation. In particular, this index could be measured in vivo according to the PPD (Persistent Pigment Darkening) method: the "PPD" measures the skin color observed 2 to 4 hours after exposure to UVA. This method has been adopted since 1996 by the Japan Cosmetic Industry Association (JCIA) as an official test procedure for the UVA labeling of products and is frequently used by testing laboratories in Europe and the United States (Japan Cosmetic Industry Association Technical Bulletin. Measurement standards for the effectiveness of protection against UVA issued on November 21, 1995 and in force since January 1, 1996). The evaluation of UVA protection can also be measured in vitro with the Labsphere® spectrophotometer. The plate is the material on which the sunscreen composition is applied. For this protocol, polymethyl methacrylate (PMMA) sheets have proven to be ideal. ISO protocol 24443 describes such an in vitro method.

Cosmetic processes and uses

The present invention also relates to the non-therapeutic cosmetic use of composite materials comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above, for filtering UV radiation, preferably UV-B, comprising at least the application to keratin materials of a composition comprising at least said composite material.

The present invention also relates to a non-therapeutic cosmetic process for filtering UV radiation, in particular UV-B, comprising at least the application to keratin materials of a composition comprising at least one composite material comprising at least a) a particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above.

According to yet another of its aspects, the present invention also relates to the non-therapeutic cosmetic use of a cosmetic composition comprising at least one composite material comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above, for preventing the appearance on the skin, in particular on the face, décolleté, arms, hands and/or shoulders, of darker and/or more colored spots giving the skin a color heterogeneity.

The present invention also relates to a non-therapeutic cosmetic process for limiting the darkening of the skin and/or improving the color and/or uniformity of the complexion comprising the application to the surface of the keratin material of at least one cosmetic composition comprising at least one composite material comprising at least a) a particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above.

The present invention further relates to the non-therapeutic cosmetic use of a cosmetic composition comprising at least one composite material comprising at least a) a particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above, for preventing premature aging of the skin, in particular of the skin of the face, décolleté, arms, hands and/or shoulders.

It also relates to a non-therapeutic cosmetic process for preventing and/or treating the signs of aging of a keratin material comprising the application to the surface of the keratin material of at least one cosmetic composition comprising at least one composite material comprising at least a) a particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above.

According to one of its aspects, the present invention relates to composite materials comprising at least a) a particle of bismuth oxycarbonate of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm and b) at least one inorganic compound as defined above, for their use as agents for the filtration of UV radiation, in particular UV-B.

For the purposes of the present invention, the term " prevent " or " prevention " means reducing, at least in part, the risk of occurrence of a given phenomenon, for example the signs of aging of a keratin material or the appearance on the skin of darker and/or more colored spots giving the skin a heterogeneity of color and/or premature aging of the skin.

In the description and examples, the percentages are weight or molar percentages. The ingredients are mixed, in the order and under the conditions easily determined by those skilled in the art.

The invention will now be described by means of the following examples given of course as illustrations and not as limitations of the invention.

Example 1 : Preparation of Bismuth Oxycarbonate Particles According to the Invention

A solution of bismuth nitrate pentahydrate Bi(NO ₃ ) ₃ ·5H ₂ O (0.40 M) and D-mannitol (0.87 M) is prepared in 800 mL of water and stirred until the reagents are completely dissolved. 160 mL of ammonium carbonate solution (2.1 equivalents relative to bismuth) are then added. A white solid precipitates. This mixture is then transferred to a Teflon autoclave reactor and heated for 7.5 hours at 125 °C. The product is isolated by centrifugation and washed 3 times with water before being dried in an oven at 60 °C.

The morphology of bismuth oxycarbonate particles was determined by direct observation by transmission electron microscopy. 1 to 5 milligrams of dry particles were dispersed in 10 mL of absolute ethanol and treated in an ultrasonic bath for two minutes. 5 µL of dispersion were then placed on an observation grid (copper with a carbon surface layer) and dried in ambient air.

Observation was performed with a Hitachi HT 7700 transmission electron microscope at an accelerating voltage of 100 kV. Average dimensions were obtained via particle size measurement by image analysis using ImageJ software (C.A. Schneider, W.S. Rasband, K.W. Eliceiri, NIH Image to ImageJ: 25 years of image analysis, Nat. Methods. 9 (2012) 671–675).

The synthesized bismuth oxycarbonate particles are platelets of the following average dimensions:

Average length L: 86 nm

Average width l: 53 nm

Average thickness e: 28 nm

Example 2: Summaries of s composite materials according to the invention

Example 2 . HAS : Synthesis of s materials composites HAS bismuth oxycarbonate – Silica from silicate sodium precipitate at pH 6.5

The bismuth oxycarbonate particles according to Example 1 (2 g) are stirred in 40 mL of distilled water. While stirring, the temperature of the medium is brought to 80 °C. At this temperature, 6.64 mL (0.25 equivalent) of an aqueous solution of sodium silicate prepared from a 26.9% mass solution and diluted by a factor of 10 are added dropwise. During the addition, the pH is maintained at 6.5 with diluted sulfuric acid H ₂ SO ₄ (0.2 M). Stirring and heating are continued for 5 h, then the reaction medium is left to cool to room temperature.

After cooling, composite material A is isolated by centrifugation, washed twice with water and then left to dry in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material A is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .B : Synthesis of s materials composites B bismuth oxycarbonate – silica from sodium silicate precipitated at pH 10.5

The bismuth oxycarbonate particles according to Example 1 (2 g) are stirred in 40 mL of distilled water. While stirring, the temperature of the medium is brought to 80 °C. At this temperature, 6.64 mL (0.25 equivalent) of an aqueous solution of sodium silicate prepared from a 26.9% mass solution and diluted by a factor of 10 are added dropwise. During the addition, the pH is maintained at 10.5 with diluted sulfuric acid H ₂ SO ₄ (0.2 M). Stirring and heating are continued for 5 h, then the reaction medium is left to cool to room temperature.

After cooling, composite material B is isolated by centrifugation, washed twice with water and then left to dry in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material B is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .C: Synthesis of s materials composites C bismuth oxycarbonate – silica from tetraethylorthosilicate

The bismuth oxycarbonate particles according to Example 1 (500 mg) are stirred in 10 mL of ethanol and 1 mL of aqueous ammonia. 109 µL of tetraethylorthosilicate (0.25 equivalent) are added dropwise, with stirring. The reaction medium is kept stirring and heated to 60 °C for 2 hours.

Composite material C is isolated by centrifugation, washed twice with ethanol and then dried in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material C is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .D: Synthesis of s materials composites D bismuth oxycarbonate – silica from silicate sodium precipitated at pH 6.5

The bismuth oxycarbonate particles according to Example 1 (2 g) are stirred in 40 mL of distilled water. While stirring, the temperature of the medium is brought to 80 °C. At this temperature, 3.32 mL (0.125 equivalent) of an aqueous solution of sodium silicate prepared from a 26.9% mass solution and diluted by a factor of 10 are added dropwise. During the addition, the pH is maintained at 6.5 with diluted sulfuric acid H ₂ SO ₄ (0.2 M). Stirring and heating are continued for 5 h, then the reaction medium is left to cool to room temperature.

After cooling, the composite material D is isolated by centrifugation, washed twice with water and then left to dry in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material D is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .E : Synthesis of s materials composites E bismuth oxycarbonate – silica from tetraethylorthosilicate

The bismuth oxycarbonate particles according to Example 1 (500 mg) are stirred in 10 mL of ethanol and 1 mL of aqueous ammonia. 54 µL of tetraethylorthosilicate (0.125 equivalent) are added dropwise, with stirring. The reaction medium is kept stirring and heated to 60 °C for 2 hours.

Composite material E is isolated by centrifugation, washed twice with ethanol and then dried in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material E is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .F: Synthesis of s materials composites F bismuth oxycarbonate – silica from silicate sodium precipitated at pH 6.5

The bismuth oxycarbonate particles according to Example 1 (2 g) are stirred in 40 mL of distilled water. While stirring, the temperature of the medium is brought to 80 °C. At this temperature, 13.3 mL (0.5 equivalent) of an aqueous solution of sodium silicate prepared from a 26.9% mass solution and diluted by a factor of 10 are added dropwise. During the addition, the pH is maintained at 6.5 with diluted sulfuric acid H ₂ SO ₄ (0.2 M). Stirring and heating are continued for 5 h, then the reaction medium is left to cool to room temperature.

After cooling, the composite material F is isolated by centrifugation, washed twice with water and then left to dry in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material F is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .G: Synthesis of s materials composites G bismuth oxycarbonate – silica from tetraethylorthosilicate

The bismuth oxycarbonate particles according to Example 1 (500 mg) are stirred in 10 mL of ethanol and 1 mL of aqueous ammonia. 217 µL of tetraethylorthosilicate (0.5 equivalent) are added dropwise, with stirring. The reaction medium is kept stirring and heated to 60 °C for 2 hours.

Composite material G is isolated by centrifugation, washed twice with ethanol and then dried in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material G is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .H: Synthesis of s materials composites H bismuth oxycarbonate – silica from silicate sodium precipitated at pH 6.5

The bismuth oxycarbonate particles according to Example 1 (2 g) are stirred in 40 mL of distilled water. While stirring, the temperature of the medium is brought to 80 °C. At this temperature, 26.6 mL (1 equivalent) of an aqueous solution of sodium silicate prepared from a 26.9% mass solution and diluted by a factor of 10 are added dropwise. During the addition, the pH is maintained at 6.5 with diluted sulfuric acid H ₂ SO ₄ (0.2 M). Stirring and heating are continued for 5 h, then the reaction medium is left to cool to room temperature.

After cooling, the composite material H is isolated by centrifugation, washed twice with water and then left to dry in an oven at 60°C, under vacuum (pressure less than 100 mbar).

The composite material H is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .I: Synthesis of s materials composites I bismuth oxycarbonate – titanium dioxide from tetraisopropoxide titanium

The bismuth oxycarbonate particles according to Example 1 (2 g) are stirred in 30 mL of 2-propanol. 500 µL of an aqueous solution of sodium hydroxide (5 x 10 ^-4 mol.L ^-1 ) are added dropwise, with stirring. A solution composed of 581 µL (0.25 equivalent) of titanium tetraisopropoxide diluted in 10 mL of 2-propanol is then added dropwise to the medium with stirring. The reaction medium is kept stirring for 1 hour.

Composite material I is isolated by centrifugation, washed twice with ethanol and then dried in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material I is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .J: Synthesis of s materials composites I bismuth oxycarbonate – silica – titanium dioxide from silicate sodium precipitated at pH 6.5 Then tetraisopropoxide titanium

The bismuth oxycarbonate particles according to Example 1 (2 g) are stirred in 40 mL of distilled water. While stirring, the temperature of the medium is brought to 80 °C. At this temperature, 13.3 mL (0.5 equivalent) of an aqueous solution of sodium silicate prepared from a 26.9% mass solution and diluted by a factor of 10 are added dropwise. During the addition, the pH is maintained at 6.5 with diluted sulfuric acid H ₂ SO ₄ (0.2 M). Stirring and heating are continued for 5 h, then the reaction medium is left to cool to room temperature.

After cooling, the intermediate composite is isolated by centrifugation, washed twice with water and then left to dry in an oven at 60°C, under vacuum (pressure less than 100 mbar).

1.86 g of particles of this intermediate composite are stirred in 30 mL of 2-propanol. 500 µL of an aqueous solution of sodium hydroxide (5 x 10 ^-4 mol.L ^-1 ) are added dropwise, with stirring. A solution composed of 563 µL of titanium tetraisopropoxide diluted in 10 mL of 2-propanol is then added dropwise to the medium with stirring. The reaction medium is kept stirring for 1 hour.

The composite material J is isolated by centrifugation, washed three times with ethanol and then dried in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material J is obtained in the form of a white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .K: Synthesis of s materials composites Y bismuth oxycarbonate – silica not in accordance with the invention from s illicit sodium precipitated at pH 6.5

Of bismuth oxycarbonate particles not in accordance with the invention (Alfa Aesar commercial reference: platelet particles of (BiO)₂CO₃, 500 nm in diameter and 50 nm thick) (2 g) are stirred in 40 mL of distilled water. While stirring, the temperature of the medium is brought to 80 °C. At this temperature, 6.64 mL (0.25 equivalent) of an aqueous solution of sodium silicate prepared from a 26.9% mass solution and diluted by a factor of 10 are added dropwise. During the addition, the pH is maintained at 6.5 with sulfuric acid H₂SO₄diluted (0.2 M). Stirring and heating are continued for 5 h, then the reaction medium is left to cool to room temperature.

After cooling, the composite material Y is isolated by centrifugation, washed twice with water and then left to dry in an oven at 60°C, under vacuum (pressure less than 100 mbar).

Composite material Y is obtained as an off-white powder and is characterized by UV/Vis spectrophotometry.

Example 2 .L : Synthesis of s materials composites Z bismuth oxycarbonate – silica not in accordance with the invention from tetraethylorthosilicate

Of bismuth oxycarbonate particles not in accordance with the invention (Alfa Aesar commercial reference: platelet particles of (BiO)₂CO₃, 500 nm in diameter and 50 nm thick) (500 mg) are stirred in 10 mL of ethanol and 1 mL of aqueous ammonia. 109 µL of tetraethylorthosilicate (0.25 equivalent) are added dropwise, with stirring. The reaction medium is kept stirring and heated to 60 °C for 2 hours.

The composite material Z is isolated by centrifugation, washed twice with ethanol and then dried in an oven at 60°C, under vacuum (pressure less than 100 mbar).

The composite material Z is obtained in the form of an off-white powder and is characterized by UV/Vis spectrophotometry.

Example 2.M: Summary and dimensions of materials A to J, Y and Z

The average sizes of the largest dimensions of the core and bark were determined by direct observation by transmission electron microscopy.

1 to 5 milligrams of dry particles are dispersed in 1 mL of absolute ethanol and treated in an ultrasonic bath for two minutes. 5 µL of dispersion are then placed on an observation grid (copper with a carbon surface layer) and dried in ambient air.

Observation was performed with a Hitachi HT 7700 transmission electron microscope at an accelerating voltage of 100 kV. Average dimensions were obtained via particle size measurement by image analysis using ImageJ software ( CA Schneider, WS Rasband , KW Eliceiri , NIH Image to ImageJ : 25 years of image analysis , Nat. Methods. 9 (2012) 671–675 ).

The particle sizes used to form the composite materials are grouped in the following Table 1.

Product Average size of the largest dimension Compound(s) pH addition (Organic) _{2- x} CO ₃ [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w HAS 80 nm 4 ± 2 nm Sodium silicate 6.5 B 80 nm 4 ± 2 nm Sodium silicate 10.5 C 80 nm / TEOS / D 80 nm 5 ± 3 nm Sodium silicate 6.5 E 80 nm / TEOS / F 80 nm 10 ± 3 nm Sodium silicate 6.5 G 80 nm / TEOS / H 80 nm 10 ± 4 nm Sodium silicate 6.5 I 80 nm / Titanium tetraisopropoxide / I 80 nm / 1/ Sodium silicate
2/ Titanium tetraisopropoxide 6.5 Y Non-compliant
(500 nm) / Sodium silicate 6.5 Z Non-compliant
(500 nm) / TEOS /

Example 3 : Spectra of ’ absorbances of materials composites d ’ bismuth oxycarbonate conforming to l ’ invention

The absorbance spectra by UV-visible spectrophotometry of the composite materials prepared according to example 2 were carried out.

They were obtained by UV-visible spectrophotometry on dispersions at 0.005% by mass of composite material in water for composite materials A to H, J, Y and Z and in a water/propylene glycol/polysorbate 20 mixture (Tween 20, marketed by the company Acros Organics) of respective mass fractions 49.85/49.85/0.30 for composite material I.

The quartz cell used for absorbance measurements is 1 cm on each side. The spectrophotometer used is the Genesys 10S from Thermo Fischer Scientific.

Preparation of dispersions

The dispersion of composite materials of bismuth oxycarbonate and inorganic oxide, at 0.10% by mass in water for composite materials A to H, J, Y and Z, or in a water/propylene glycol/polysorbate 20 mixture of respective mass fractions 49.85/49.85/0.30 for composite material I, is exposed to ultrasound for 2 minutes and then stirred with a magnetic stirrer for 16 hours. It is then diluted to 0.005% by mass in bismuth oxycarbonate in the same solvent or mixture of solvents and stirred again for 20 minutes. The absorbance measurement is then carried out.

The spectra of the materials in accordance with the invention (A to J) are compared with bismuth oxycarbonate – silica particles not in accordance with the invention (materials Y and Z) prepared from a commercial reference of bismuth oxycarbonate (BiO) ₂ CO ₃ obtained from Alfa Aesar (platelet particles of approximately 500 nm in diameter by 50 nm in thickness).

Beyond a predetermined threshold value of UV absorbance measurement, the filtration of UV radiation is considered effective. In particular, composite materials having a UV absorbance threshold, in the dispersion medium comprising said composite materials, at a mass fraction of 0.005%, greater than 0.25 are considered effective for the filtration of UV radiation.

The absorbance spectra are shown in Figures 1 to 12.

The results are grouped in the following Table 2.

Absorbance Composite A Composite B Composite C Composite D Composite E Composite F Absorbance at 220 nm 0.61 0.44 0.54 0.52 0.42 0.44 Absorbance at 300 nm 0.72 0.54 0.62 0.62 0.48 0.50 Absorbance at 400 nm 0.34 0.36 0.44 0.36 0.28 0.28 Absorbance at 620 nm 0.12 0.16 0.18 0.14 0.10 0.12 Absorbance Composite G Composite H Composite I Composite J Composite Y (excluding invention) Composite Z (excluding invention) Absorbance at 220 nm 0.40 0.54 0.60 0.42 0.11 0.08 Absorbance at 300 nm 0.44 0.56 0.66 0.50 0.10 0.10 Absorbance at 400 nm 0.34 0.28 0.36 0.34 0.10 0.09 Absorbance at 620 nm 0.18 0.10 0.16 0.16 0.08 0.08

The composite materials according to the invention show good absorbance of UV rays and therefore effective filtration of UV rays, and in particular of the UV-B range. On the contrary, the comparative composite materials Y and Z show low absorbance, and do not allow sufficient filtering of the entire UV range.

The absorbance spectra also show that the composite materials according to the invention have a high transparency in the visible range between 400 and 780 nm.

Claims (17)

Use of a composite material comprising:

1. at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ) , as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm; and
2. at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w ;

in which:

• y is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably y is less than 10, more preferably less than 5, and even more preferably y denotes 1 or 2 or 3;
• z is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably z is less than 10, more preferably less than 5;
• t is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably t is less than 10, more preferably t is less than 5;
• M is a metal, an alkaline earth metal or a metalloid, preferably selected from silicon Si, titanium Ti, iron Fe, zinc Zn, niobium Nb, tantalum Ta, cerium Ce, manganese Mn, bismuth Bi, tungsten W, aluminum Al, copper Cu and indium In, preferably M denotes Si or Al;
• v denotes the oxidation state of M and is a number between 1 and 8, preferably v is less than or equal to 6, and more preferably less than or equal to 4;
• w is an integer or fractional number ranging from 0 to 20;
• p is an integer ranging from 1 to 5, preferably p is less than or equal to 3, more preferably less than or equal to 2, even more preferably equal to 1;
• q is an integer ranging from 1 to 5, preferably q is less than or equal to 2, more preferably q is equal to 1; and
• for each inorganic compound: ;

for the filtration of UV-A rays, and/or UV-B rays, preferably UV-B rays, particularly for protecting keratin materials, in particular human materials such as skin, and/or keratin fibres, in particular human materials such as hair;
it being understood that when b) is TiO₂, then the composite material is in the form of “heart / bark" Or "core / shell»
preferably, the average size of the largest particle dimension of said composite material is less than or equal to 450 nm. Use according to the preceding claim in which said composite material comprises:
Let i):

• a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, according to the preceding claim; and
• a bark comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w according to the preceding claim;

Either ii):

• a core comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w according to the preceding claim;
• a shell comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, such as the hydrates according to the preceding claim;
• preferably, it being understood that the average size of the largest particle dimension of composite material is less than or equal to 450 nm;

and more preferably, said composite material comprises:

• a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, according to the preceding claim; and
• a bark comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w according to the preceding claim.

Use according to any one of the preceding claims, wherein said composite material has an average size of the largest particle dimension of composite material varying from 10 nm to 300 nm, preferably from 25 nm to 250 nm, and more preferably from 40 nm to 200 nm. Use according to any one of the preceding claims, in which the molar ratio between the number of moles of coating compound(s) and the number of moles of core compound(s) varies from 0.0001 to 20, preferably from 0.005 to 10, better still from 0.01 to 5, even better still from 0.02 to 2, and even more preferably from 0.05 to 1. Use according to any one of the preceding claims, said bismuth oxycarbonate particles being crystallized. Use according to any one of the preceding claims, said bismuth oxycarbonate particles being of formula (BiO) ₂ (CO ₃ ). Use according to any one of the preceding claims, the largest average dimension of said bismuth oxycarbonate particles being less than or equal to 300 nm. Use according to any one of the preceding claims, said bismuth oxycarbonate particles being in the form of tubes, platelets and/or rods, preferably in the form of platelets and/or rods. Use according to any one of the preceding claims, said inorganic compound(s) b) being chosen from the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ , TiO ₂ , Fe ₂ O ₃ , ZnO, Nb ₂ O ₅ , In ₂ O ₃ , CeO ₂ , Bi ₂ O ₃ and their mixtures, more preferably the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ , TiO ₂ , Fe ₂ O ₃ , ZnO and their mixtures, and even more preferably the hydrated or non-hydrated forms of Al ₂ O ₃ , SiO ₂ and their mixtures. Composite material comprising:
Let i):

• a core comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm; and
• a bark comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w ;

in which:

• y is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably y is less than 10, more preferably less than 5, and even more preferably y denotes 1 or 2 or 3;
• z is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably z is less than 10, more preferably less than 5;
• t is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably t is less than 10, more preferably t is less than 5;
• M is a metal, an alkaline earth metal or a metalloid, preferably selected from silicon Si, titanium Ti, iron Fe, zinc Zn, niobium Nb, tantalum Ta, cerium Ce, manganese Mn, bismuth Bi, tungsten W, aluminum Al, copper Cu and indium In, preferably M denotes Si or Al;
• v denotes the oxidation state of M and is a number between 1 and 8, preferably v is less than or equal to 6, and more preferably less than or equal to 4;
• w is an integer or fractional number ranging from 0 to 20;
• p is an integer ranging from 1 to 5, preferably p is less than or equal to 3, more preferably less than or equal to 2, even more preferably equal to 1;
• q is an integer ranging from 1 to 5, preferably q is less than or equal to 2, more preferably q is equal to 1; and
• for each inorganic compound: ;

Either ii):

• a core comprising at least b) at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w in which M ^(v) _y , p, z, t, q, and w are as defined above;
• a shell comprising at least a) at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm;
• it being understood that the average size of the largest particle dimension of composite material is less than or equal to 450 nm.

A method of preparing a composite material according to any preceding claim, comprising the steps of:

1. having a dispersion of bismuth oxycarbonate particles a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, in at least one solvent, in particular in an amount ranging from 0.05 g/L to 500 g/L;
2. have an aqueous solution of sodium silicate b), in particular in a molar ratio Si/Bi of between 0.001 and 10, preferably of between 0.01 and 2, and even more preferably of between 0.1 and 1;
3. bringing together said dispersion (i) and said solution (ii) to form the composite material;
4. isolate said composite material.

A process for preparing a composite material according to any one of claims 1 to 10, comprising the steps of:
(1) having a dispersion of bismuth oxycarbonate particles a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, in at least one solvent, in particular in an amount ranging from 0.05 g/L to 500 g/L;
(1') adding a basic aqueous solution, preferably aqueous ammonia to said dispersion (1);
(2) have a solution of at least one silicon tetraalkoxide b);
(3) bringing together said dispersion (1') and said solution (2) to form the composite material;
(4) insulate said composite material. A process for preparing a composite material according to any one of claims 1 to 10, comprising the steps of:
(a) having a dispersion of bismuth oxycarbonate particles a) of formula (I) (BiO) _2-x (CO ₃ ), as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm, in at least one solvent, in particular in an amount ranging from 0.05 g/L to 500 g/L;
(a') optionally adding a basic aqueous solution, preferably sodium hydroxide, preferably with a pH ranging from 8 to 13, and more preferably from 9 to 12, to said dispersion (a);
(b) having a solution of at least one titanium tetraalkoxide b), optionally in at least one solvent, in particular in a Ti/Bi molar ratio varying from 0.001 to 2, more preferably from 0.01 to 1.5, and more preferably from 0.1 to 1;
(c) bringing together said dispersion (a') and said solution (b) to form the composite material;
(d) insulating said composite material. Composition, in particular cosmetic, comprising at least one composite material according to any one of claims 1 to 10. Composition according to the preceding claim comprising at least:
i) at least one composite material according to any one of claims 1 to 10;
ii) at least one aqueous phase and/or at least one fatty phase; and
iii) at least one compound chosen from: 1) UV filters distinct from composite materials i); 2) coloring matters; 3) cosmetic active ingredients for the care of keratin materials; 4) surfactants; 5) thickeners; and mixtures thereof. Composition according to any one of claims 14 or 15, said composite materials being present in a content ranging from 0.5% to 70% by weight, preferably from 1% to 50% by weight, even better from 2 to 40% by weight, relative to the total weight of the composition. Non-therapeutic cosmetic process for filtering UV radiation, preferably UV-B, comprising at least the application to keratin materials of a composition comprising a composite material comprising:

1. at least one particle of bismuth oxycarbonate of formula (I) (BiO) _{2- x} (CO ₃ ) , as well as its solvates, such as its hydrates, in which -0.4 < x < 0.6, the largest average dimension of said particles being less than 400 nm; and
2. at least one inorganic compound chosen from the oxides and/or hydroxides of formula [(M ^(v) _y ) _p O _z (OH) _t ] _q (H ₂ O) _w ;

in which:

• y is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably y is less than 10, more preferably less than 5, and even more preferably y denotes 1 or 2 or 3;
• z is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably z is less than 10, more preferably less than 5;
• t is an integer greater than or equal to 1 and less than or equal to 100, preferably less than or equal to 50, preferably t is less than 10, more preferably t is less than 5;
• M is a metal, an alkaline earth metal or a metalloid, preferably selected from silicon Si, titanium Ti, iron Fe, zinc Zn, niobium Nb, tantalum Ta, cerium Ce, manganese Mn, bismuth Bi, tungsten W, aluminum Al, copper Cu and indium In, preferably M denotes Si or Al;
• v denotes the oxidation state of M and is a number between 1 and 8, preferably v is less than or equal to 6, and more preferably less than or equal to 4;
• w is an integer or fractional number ranging from 0 to 20;
• p is an integer ranging from 1 to 5, preferably p is less than or equal to 3, more preferably less than or equal to 2, even more preferably equal to 1;
• q is an integer ranging from 1 to 5, preferably q is less than or equal to 2, more preferably q is equal to 1; and
• for each inorganic compound: .