WO2018220420A1

WO2018220420A1 - Method for protecting keratinous materials against uv radiations

Info

Publication number: WO2018220420A1
Application number: PCT/IB2017/000865
Authority: WO
Inventors: Sarah Sebban
Original assignee: Chanel Parfums Beaute
Priority date: 2017-06-02
Filing date: 2017-06-02
Publication date: 2018-12-06

Abstract

The invention relates to a method for protecting keratinous materials, particularly the skin, against UV radiations comprising applying successively, to the keratinous materials: 1/ a base composition comprising an UV filter, 2/ a finishing composition comprising an UV filter, wherein at least one of the base composition or the finishing composition comprises at least one compound chosen from: - a silicon polymer A having silicon-bonded alkenyl groups called "Si-Alkenyl" groups, - a silicon polymer B having silicon-bonded hydrogens groups called "SiH" groups, - a catalyst C, and mixtures thereof, with the proviso that: - at least one polymer A, one polymer B and one catalyst C are present in either the base or the finishing composition, and that - the polymer A, the polymer B and the catalyst C are not present simultaneously in the same composition, said polymer A and polymer B being capable of reacting together by a hydrosilylation reaction in the presence of said catalyst C when they are contacted with one another, in order to form, on the keratinous material, a continuous protecting film against UV radiations.

Description

Method for protecting keratinous materials against UV radiations

The present invention relates to a method for protecting keratinous materials, particularly the skin, against UV radiations comprising the application to said keratinous materials of a base composition comprising an UV filter and of a finishing composition comprising an UV filter, the base composition and the finishing composition being silicon- based and being capable of reacting together in order to form a film.

Silicon-based products capable of reacting together in order to form a film have been described in the prior art, in particular in order to improve the persistence of cosmetic care or make-up over time.

Document WO 2011/003054 for example relates to silicone containing compositions capable of forming adhesive films on substrates, which comprises a curable silicone composition comprising components (a), (d) and one of (b) or (c): (a), a polyorganosiloxane resin having at least 3 alkenyl groups per molecule, called "SiVi" groups, (b). a polyorganosiloxane compound having at least 2 Si-bonded hydrogen groups on the polysiloxane chain, called "SiH" groups, (c). a telechelic polyorganosiloxane compound having terminal Si-H groups, and (d). a hydrosilylation catalyst for the reaction of SiH groups with SiVi groups, (e). a liquid diluent, said components reacting together by hydrosilylation when they are brought into contact on a substrate and cure to form a continuous film on the substrate.

Silicon-based compositions for protecting keratinous materials from the sun have also been described in the prior art. Document EP 2 153 817 for example describes a method of protecting keratinous materials against UV radiation, comprising the application to said materials of a) at least one compound (X), b) at least one compound (Y), and c) at least one hydrophobic screening system; at least one of said compounds (X) and (Y) being a silicone compound, said compounds (X) and (Y) being capable of reacting together, said reaction being a hydrosilylation reaction in the presence of at least one catalyst, a condensation reaction or a crosslinking reaction in the presence of at least one peroxide, with the proviso that the applications a), b) and c) take place either (i) simultaneously by extemporaneous mixing beforehand, or (ii) by mixing at the time of their application, simultaneously or sequentially in any order, subject to the proviso that the conditions of said mixing are beneficial to the reaction between said compounds (X) and (Y).

However, there is still a need to further improve the protection of keratinous materials against UV radiations. The aim of the present invention is thus to improve the UV protection provided by sunscreen products. The present invention provides photoprotective films showing an increased efficacy against UV rays, in other words having improved SPF values.

The sun protection factor (SPF) is a measure of the protection from the sun provided by a sunscreen product. Products having higher SPF values provides a more effective sun protection. SPF values range from about 1 to 50+, SPF values of 1-4 indicating minimal sun protection, 4-6 indicating moderate sun protection, 8-15 indicating high sun protection, and above 15 indicating maximal protection.

The method used herein for the in vitro SPF measurement is conducted according to the "IN VITRO METHOD FOR THE DETERMINATION OF THE UVA PROTECTION FACTOR AND "CRITICAL WAVELENGTH" VALUES OF SUNSCREEN PRODUCTS", prepared by the "COLIPA In vitro UV Protection Method Task Force", March 2011.

Another aim of the invention is to provide sunscreen products having a comfortable deposit on the skin, which are not sticky and having long-lasting anti-UV properties.

The Inventors have now surprisingly discovered that when an UV filter is present in a base composition and another UV filter is present in a finishing composition, the base composition and the finishing composition being silicon-based and being capable of reacting together in order to form a film, then the mixture of said two compositions when applied to the skin allows to obtain a film having an unexpectedly high SPF value, at least equal or preferably higher than to the sum of the SPF values of the base and the finishing compositions.

The Inventors have also shown that obtaining a film with an improved SPF as described above is possible even if a cosmetic composition, for example a skin care composition, is applied to the keratinous material, in particular the skin, before the application of the base composition.

According to a first aspect, the present invention is directed to a method for protecting keratinous materials, particularly the skin, against UV radiations comprising applying successively, to the keratinous materials:

1/ a base composition comprising an UV filter,

21 a finishing composition comprising an UV filter, wherein at least one of the base composition or the finishing composition comprises at least one compound chosen from:

- a silicon polymer A having silicon-bonded alkenyl groups called "Si-Alkenyl" groups,

- a silicon polymer B having silicon-bonded hydrogens groups called "SiH" groups, - a catalyst C,

and mixtures thereof,

with the proviso that:

- at least one polymer A, one polymer B and one catalyst C are present in either the base or the finishing composition, and that

- the polymer A, the polymer B and the catalyst C are not present simultaneously in the same composition,

said polymer A and polymer B being capable of reacting together by a hydrosilylation reaction in the presence of said catalyst C when they are contacted with one another,

in order to form, on the keratinous material, a continuous protecting film against UV radiations.

The hydrosilylation reaction between the Si-Alkenyl groups of polymer A and the SiH groups of polymer B may be depicted in a simplified way as follows: — Si— H + CH₂=CH— W → — Si— CH₂— CH₂— W

(Polymer B) (Polymer A) where W represents a silicone chain containing one or more unsaturated aliphatic groups.

According to an embodiment of the invention, the silicon polymer A comprises at least two unsaturated aliphatic groups. By way of example, the silicon polymer A may be a polyorganosiloxane comprising a silicone main chain, whose unsaturated aliphatic groups are pendant to the main chain (side group) or are located at the ends of the main chain of the compound (terminal group): such compounds are referred to polyorganosiloxanes containing unsaturated aliphatic groups.

In one embodiment, the silicon polymer A is selected from polyorganosiloxanes comprising at least two unsaturated aliphatic groups, for example two or three vinyl or allyl groups, which are each bonded to a silicon atom. In one advantageous embodiment the silicon polymer A is more particularly selected from polyorganosiloxanes comprising siloxane units of the formula (I):

2

in which:

* R represents a monovalent, linear, branched or cyclic hydrocarbon group containing 1 to 30 carbon atoms, preferably 1 to 20, and more preferably 1 to 10 carbon atoms, said hydrocarbon group may also comprise at least one or more unsaturated groups or R represents an aryl group such as phenyl,

* m is 1 or 2 and,

* R' represents:

• an unsaturated aliphatic hydrocarbon group, linear or branched, containing 2 to 10, preferably 3 to 5 carbon atoms such as, for example, a vinyl group or a group— R"— CH=CHR"' in which R" is a divalent aliphatic hydrocarbon chain, linear or branched, containing 1 to 8 carbon atoms and is bonded to the silicon atom and R'" is a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, preferably a hydrogen atom, or

• an unsaturated cyclic hydrocarbon group containing 5 to 8 carbon atoms such as, for example, a cyclohexenyl group.

Groups R' include vinyl and allyl groups and mixtures thereof.

In one particular embodiment, the polyorganosiloxane A also comprises units of formula (II):

2

in which:

R is a group such as defined above, and n is 1, 2 or 3.

In one variant, the silicon polymer A may be a silicone resin comprising at least two ethylenic unsaturations, and preferably 3 ethylenic unsaturations, said resin being able to react with the silicon polymer B. Mention may be made, for example, of the resins of type MQ or MT which itself carries unsaturated reactive — CH=CH2 end groups. These resins are crosslinked organosiloxane polymers.

The nomenclature of silicone resins is known under the name "MDTQ", the resin being described as a function of the different monomeric siloxane units it comprises, with each of the letters "MDTQ" characterizing one type of unit.

The letter M represents the monofunctional unit of formula (CH₃)₃SiOi_/2, the silicon atom being bonded to a single oxygen atom in the polymer comprising this unit. The letter D signifies a difunctional unit (CH₃)₂Si0_2/2 in which the silicon atom is bonded to two oxygen atoms.

The letter T represents a trifunctional unit of formula (CH3)Si03/₂ in which the silicon atom is bonded to three oxygen atoms.

In the above-defined units M, D and T, at least one of the methyl groups may be substituted by a group R other than the methyl group, such as a hydrocarbon radical (especially alkyl), linear or branched, having 2 to 10 carbon atoms or a phenyl group or else a hydroxy 1 group.

The letter Q signifies a tetrafunctional unit S1O₄/2 in which the silicon atom is bonded to four hydrogen atoms which are themselves bonded to the remainder of the polymer. Examples of such resins include the MT silicone resins such as the poly(phenyl-vinylsilsesquioxanes).

Resins comprising R3S1O1/2 units and S1O₄/2 units are well known in the art. These copolymers are described, for example, in U.S. Pat. Nos. 3,936,582, 2,676,182, and 2,857,356.

The silicon polymer A preferably contains from 0.01% to 1% by weight of unsaturated aliphatic groups or from 0.00001 mol/g as vinyl group based on the weight of the polymer to 0.1 mol/g as vinyl group based on the weight of the polymer.

Advantageously, the silicon polymer A is selected from polyorganopolysiloxanes, especially those comprising the siloxane units (I) and, optionally, (II) described above, and from silicone resins of MQ type.

The silicon polymer A may be present in the base composition or in the finishing composition in a content ranging from 15 to 95 % by weight, and preferably from 35 to 65 % by weight relative to the total weight of the composition.

According to another embodiment of the invention, the silicon polymer B is an organosiloxane comprising at least two free Si— H groups (hydrosilane groups).

The silicon polymer B may advantageously be selected from polyorganosiloxanes comprising at least one alkylhydrosiloxane unit of formula (III) below:

2

in which:

* R represents a monovalent, linear, branched or cyclic hydrocarbon group containing 1 to 30 carbon atoms, preferably 1 to 20, and more preferably 1 to 10 carbon atoms, such as, for example, a short-chain alkyl radical, containing, for example, 1 to 10 carbon atoms, more particularly a methyl radical or else a phenyl group,

* p is 1 or 2. These polyorganosiloxane B containing alkylhydrosiloxane units may further comprise units of formula (II) as defined above.

The silicon polymer B may be a silicone resin comprising at least one unit selected from the units M, D, T, and Q as defined above and comprising at least one Si— H group, such as the poly(methylhydridosilsesquioxanes) sold under the name SST-3 MH1.1 by Gelest.

These polyorganosiloxane B preferably contain from 0.5% to 2.5% by weight of Si— H groups.

Advantageously, the radicals R represent a methyl group in formulae (I), (II), (III) above.

These polyorganosiloxanes B preferably comprise end groups of formula (CH₃)₃SiOi/2. Advantageously, these polyorganosiloxanes B comprise at least two alkylhydrosiloxane units of formula -(H₃C)(H)SiO- and optionally comprise -(H3C)₂SiO- units.

The silicon polymer B may be present in the base composition or in the finishing composition in a content ranging from 15 to 95 % by weight, and preferably from 35 to 65 % by weight relative to the total weight of the composition.

The catalyst C used in the present invention comprises those known in the art to facilitate the hydrosilylation reaction. These include, for example, platinum and rhodium materials. These catalysts may take any of the known forms such as platinum or rhodium deposited on carriers such as silica gel or powdered charcoal or other appropriate compounds such as platinic chloride, salts of platinum and chloroplatimc acids, chloroplatimc acid either as the commonly obtainable hexahydrate or the anhydrous form because of its easy dispersibility in organosilicon systems and its non-effect on colour of the mixture. Platinum or rhodium complexes may also be used e.g. those prepared from chloroplatimc acid hexahydrate and divinyltetramethyldisiloxane.

The hydrosilylation catalyst C according to the invention is advantageously a platinum based catalyst or a rhodium based catalyst, and in particular a platinum complex stabilized by diviny ltetramethy ldisilo xane . The hydrosilylation catalyst C may be present in the base composition or in the finishing composition in a content ranging from 0.0001% to 0.01% by weight, and preferably from 0.0001% to 0.001% by weight relative to the total weight of the composition. In one particular embodiment, the silicon polymer A is a polydimethylsiloxane containing vinyl end groups, and the silicon polymer B is a polymethylhydrosiloxane.

As an example of a combination of silicon polymer A and silicon polymer B reacting by hydrosilylation in the presence of a catalyst C, mention may be made of the following references provided by Dow Corning: Dow Corning ® DC 7-FC4210 Elastomer Parts A & B.

More particularly Dow Corning ® DC 7-FC4210 Elastomer is a 2-part solvent-less silicone film-forming technology. It is a thermoset silicone rubber system, with a fast cure at room temperature.

The composition of the two parts are described below.

Part A (Dow Corning 7-FC4210 Elastomer Film Forming Base ®):

· Reinforced silicone phase: vinyl-terminated polydimethylsiloxane and treated silica,

• Catalyst: platinum complex,

• INCI name: Bis-Vinyldimethicone (and) Silica Silylate (and) Platinum Diviny ldisilo xane . Part B (Dow Corning 7-FC4210 Curing Agent ®) :

• Reinforced silicone phase: vinyl-terminated polydimethylsiloxane and treated silica,

• Cross-linking agent: methylhydrogen siloxane,

• INCI name: Bis-Vinyldimethicone (and) Silica Silylate (and) Hydrogen dimethicone. More particularly, when silicon polymer A and silicon polymer B are brought into contact in the presence of the catalyst C at room temperature, the system cures rapidly (from 2 to 5 minutes) in order to form a film which adheres to the skin. Said resulting forming film is a network of cross-linked and reinforced silicone polymer.

According to an advantageous embodiment of the invention, the ratio between the silicon polymer A and the silicon polymer B is 1 : 1 , or approximatively 1 : 1 that is to say from 0.8: 1 to 1 :0.8. In such a way, the cross-linking reaction between the silicon polymer A and the silicon polymer B is complete and the resulting film is dry, non-sticky, soft, flexible, elastic and long lasting. Such a film is thus very comfortable when formed on the keratinous materials. According to an embodiment of the invention, the thickness of the resulting film is from 5 to 15 μιη.

In a preferred embodiment, in order to achieve the best results, the base composition first applied should be fully covered by the finishing composition.

In fact, if the base composition is applied to the skin without being fully covered with the finishing composition, the user may feel a sticky effect on the areas of the skin that where not fully covered by the finishing composition.

In the same manner, the application of a finishing composition in an area where no base composition was previously applied may also result in a sticky sensation for the user.

If no sticky sensation is felt by the user, he is thus ensured that the film is properly formed on his face and presents the desired SPF value.

According to an embodiment of the method of the invention, the silicon polymer A and the catalyst C are present in the base composition and the silicon polymer B is present in the finishing composition.

According to another embodiment of the method of the invention, the silicon polymer B is present in the base composition and the silicon polymer A and the catalyst C are present in the finishing composition.

All the embodiments described below are also within the scope of the invention:

- the silicon polymer A is present in the base composition and the silicon polymer B and the catalyst C are present in the finishing composition,

- the silicon polymer B and the catalyst C are present in the base composition and the silicon polymer A is present in the finishing composition,

- the silicon polymer A and the silicon polymer B are present in the base composition and the catalyst C is present in the finishing composition,

- the catalyst C is present in the base composition and the silicon polymer A and the silicon polymer B are present in the finishing composition,

- the base composition comprises the polymer A and the catalyst C, and the finishing composition comprises another polymer A and the polymer B,

- the base composition comprises the polymer A and the polymer B, and the finishing composition comprises the catalyst C and another polymer A,

- the base composition comprises the polymer B and the catalyst C, and the finishing composition comprises the polymer A and another polymer B, - the base composition comprises the polymer A and the polymer B, and the finishing composition comprises another polymer B and the catalyst C.

Once the base composition is applied to the skin the finishing composition can be applied. It is not necessary to wait between the application of the base composition and the finishing composition in order to obtain the desired film. The resulting film is completely formed approximatively two minutes after the application of the finishing composition on the base composition.

In the present invention, the base composition has a SPF value "VA", and the finishing composition has a SPF value "VB".

Unexpectedly, once the continuous protecting film is formed by reaction of the base and finishing composition, the resulting film has SPF value VT which is equal or preferably greater than VA + VB.

According to an advantageous embodiment of the invention the UV filter present in the base composition or in the finishing composition is a mineral sunscreen chosen from zinc oxide, titanium dioxide and their mixtures.

However any of the UV filters described below may also be added to the base or to the finishing composition used in the method of the invention.

Thus the base or the finishing composition may also contain a sunscreen chosen from a mineral filter, an organic filter and their mixtures.

The mineral or inorganic UV filters used are metal oxide particles having an average elementary particle size less than or equal to 100 nm.

They may notably be selected from the oxides of titanium, zinc, iron, zirconium, cerium or mixtures thereof.

The titanium oxides may be in crystalline form of the rutile and/or anatase type, and/or in an amorphous or substantially amorphous form.

The metal oxide pigments may be coated or uncoated.

The coated pigments are pigments that have undergone one or more surface treatments of a chemical, electronic, mechanical-chemical and/or mechanical nature with compounds such as amino acids, beeswax, fatty acids, fatty alcohols, anionic surfactants, lecithins, sodium, potassium, zinc, iron or aluminium salts of fatty acids, metal alkoxides (of titanium or aluminium), polyethylene, silicones, proteins (collagen, elastin), alkanolamines, silicon oxides, metal oxides or sodium hexametaphosphate. According to the invention, titanium oxide or zinc oxide pigments, coated or uncoated, are particularly preferred as mineral or inorganic UV filter.

As an example of coated titanium oxide pigment, one can cited a pigment titanium oxide coated with aluminium hydroxide and stearic acid marketed by the company Titan Kogyo under the name ST 705 SA.

The mineral or inorganic UV filter may be present in the base composition or in the finishing composition in a content ranging from 0.1 % to 40 % by weight, and preferably from 5 % to 25 % by weight, relative to the total weight of the composition.

By way of illustration of organic UV filters, we may mention, non-exhaustively:

anthranilates, benzophenones, benzylidene-camphors, benzimidazoles, benzotriazoles, cinnamates, diphenylacrylates, dibenzoylmethanes, PABAs, triazines, benzoates, benzal malonates, benzoxazoles, salicylates.

The preferred organic filters are selected from Phenylbenzimidazole sulfonic acid

(Parsol HS), Octocrylene (Parsol 340), Ethylhexyl Methoxycinnamate (Parsol MCX), Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (Tinosorb M), Bis- Ethylhexyloxyphenol Methoxyphenyl Triazine (Tinosorb S), Tris-Biphenyl Triazine (Tinosorb 2AB), Ethylhexyl Triazone (UVINUL T150), Diethylhexyl Butamido Triazone (UVASORB HEB), Diethylamino Hydroxybenzoyl Hexyl Benzoate (UVINUL A PLUS), Butyl Methoxydibenzoylmethane (PARSOL 1789), Polysilicone-15 (PARSOL SLX), Benzophenone-4 (Uvinul MS 40), Benzophenone-3 Ethylhexyl Salicylate (Parsol EHS), Homosalate and mixtures thereof. The organic UV filter may be present in the base composition or in the finishing composition in a content ranging from 0.1 % to 40 % by weight, and preferably from 5 % to 25 % by weight, relative to the total weight of the composition.

The base composition and the finishing composition used in the method of the invention may be in any galenic form conventionally used for topical application. They may in particular be in the form of a powder, an emulsion, a microemulsion, a nano emulsion, a suspension, a solution, a lotion, a cream, an aqueous or hydroalcoholic gel, a foam, a serum, an aerosol dispersion, an anhydrous composition.

In the case of an emulsion, it may be a water-in-oil or oil-in-water emulsion. In the case of a powder, it may be a free, compact or cast powder, or a composition obtained by a "slurry" type method, that is, by dispersing a pulverulent phase in a volatile solvent phase, and then evaporation of the volatile solvent phase. A person skilled in the art may select the appropriate galenic form, and the method for preparing each composition, based on his general knowledge, taking into account firstly the nature of the constituents used, and secondly the intended use of the compositions.

The base and the finishing compositions used in the method according to the invention may also contain additional ingredients commonly used in cosmetics.

Fillers

The base composition and the finishing composition used in the cosmetic method or kit according to the invention may also contain at least one filler.

"Filler" means any particle of whatever shape (notably spherical or lamellar), mineral or organic, insoluble in the composition.

The composition may comprise at least one filler in a content ranging from 1 to 85 % by weight, preferably from 5 to 40 % by weight, and more preferably from 10 to 30 % by weight, relative to the total weight of the composition.

Oils

The base composition and the finishing composition used in the cosmetic method or kit according to the invention may also contain at least one oil.

In the sense of the present invention, "oil" means a compound that is liquid at room temperature (25°C), and which, when it is introduced at a rate of at least 1 % by weight in water at 25°C, is not at all soluble in water, or is soluble to a level of less than 10 % by weight, relative to the weight of oil added to the water.

As oils that may be used in the invention, we may notably mention: linear or branched hydrocarbons of mineral origin or synthetic origin, synthetic (poly)esters and (poly)ethers and in particular (poly)esters of C6-C20 acids and of C6-C20 alcohols, advantageously branched, such as isononyl isononanoate, vegetable oils, branched and/or unsaturated fatty acids, branched and/or unsaturated fatty alcohols, silicone oils, fluorosilicone oils, fluorinated oils, and mixtures thereof. "Fluorinated oil" means an oil containing at least one fluorine atom. "Silicone oil" means an oil comprising at least one silicon atom, and notably at least one Si-0 group. The silicone oil may be volatile or non-volatile.

The following may be mentioned for example as vegetable or synthetic oils usable in the invention:

· hydrocarbon-containing oils of vegetable origin, such as liquid triglycerides of fatty acids comprising from 4 to 10 carbon atoms or else, for example, sunflower oil, maize oil, soya oil, cucurbit oil, grapeseed oil, sesame oil, hazelnut oil, apricot kernel oil, macadamia oil, arara oil, coriander oil, castor oil, avocado oil, wheat germ oil, grapeseed germ oil, sesame germ oil, karite germ oil, avocado germ oil, olive germ oil, sweet almond oil, palm oil, colza oil, cotton oil, hazelnut oil, jojoba oil, alfalfa oil, poppy oil, pumpkin oil, blackcurrant oil, evening primrose oil, millet oil, barley oil, quinoa oil, rye oil, safflower oil, candlenut oil, passionflower oil, musk rose oil or camellia oil,

• triglycerides of caprylic/capric acids,

• synthetic esters and ethers, notably of fatty acids, such as the oils of formulae R'COOR² and R'OR² in which R¹ represents a fatty acid residue comprising from 8 to 29 carbon atoms, and R² represents a hydrocarbon-containing chain, branched or not, containing from 3 to 30 carbon atoms, hydroxylated esters, polyol esters, pentaerythritol esters and mixtures of esters of coconut alcohol with caprylic and capric acid (coconut- caprylate/caprate) and of coconut alkanes, biopoly esters,

· non-volatile hydrocarbon-containing oils such as polybutene, hydrogenated polyisobutene and hydrogenated polydecene,

•volatile hydrocarbon-containing oils containing from 8 to 16 carbon atoms, and notably branched C8-C16 alkanes and volatile linear CI 1-C14 or C15-19 alkanes. Waxes and lipophilic gelling agents

The base composition and the finishing composition used in the cosmetic method or kit according to the invention may further comprise at least one wax and/or at least one lipophilic gelling agent.

"Wax" means a fat having a melting point above 30°C and generally below 100°C, which is liquid in the conditions of preparation of the composition and displays anisotropic crystalline organization in the solid state. Examples of waxes are notably the vegetable, mineral or synthetic waxes, advantageously hydrocarbon-containing or silicone-containing, such as carnauba wax, candelilla wax, rice wax, beeswax (Cera alba), polyethylene wax, optionally functionalized, and paraffin wax, as well as ozokerite, microcrystalline waxes, C14-C22 linear fatty alcohols and triesters of C8-C20 acids and of glycerin such as glycerin tribehenate, and mixtures thereof.

Examples of lipophilic gelling agents are notably silicone polymers and more particularly elastomers of organopolysiloxanes. Among the latter, we may mention the polymers, at least partially crosslinked, resulting from the reaction of an organopolysiloxane bearing unsaturated groups, such as vinyl or allyl groups, located at the end or in the middle of the chain, preferably on a silicon atom, with another reactive silicone compound such as an organohydrogen polysiloxane. These polymers are usually available in the form of gel in a volatile or non- volatile silicone solvent or in a hydrocarbon-containing solvent.

Another type of oily gelling agent consists of a silicone polymer, obtained by autopolymerization of an organopolysiloxane functionalized with epoxy groups and hydrosilylated, in the presence of a catalyst. Another lipophilic gelling agent consists of a dimethicone / cyclic vinyldimethicone copolymer. Another type of lipophilic gelling agent consists of copolymers of styrene and of olefins such as ethylene, propylene and/or butylene, optionally combined with silicone-containing or hydrocarbon-containing solvents. Another type of lipophilic gelling agent consists of polyamides such as polyamide-3 and Ethylenediamine/Hydrogenated Dimer Dilinoleate Copolymer Bis-Di-C14-18 Alkyl Amide. As a variant, the lipophilic gelling agent may be a bentone or a hydrophobic modified hectorite.

Colouring matter

The base composition and the finishing composition used in the cosmetic method or kit according to the invention may, moreover, comprise at least one colorant, which may be selected from pigments, nacres, fat-soluble dyes, flakes and mixtures thereof.

Pigments are to be understood as white or coloured particles, mineral or organic, insoluble in an aqueous solution, intended for colouring and/or opacifying the composition.

As mineral pigments usable in the invention, we may mention the oxides of titanium, of zirconium or of cerium as well as the oxides of zinc, of iron or of chromium, ferric blue, manganese violet, ultramarine blue and chromium hydrate.

It may also be a pigment having a structure that may be multi- layered, for example of the sericite/brown iron oxide/titanium dioxide/silica type.

The colorant may further comprise a pigment having a structure that may be for example of the type of silica microspheres containing iron oxide. Among the organic pigments usable in the invention, we may mention carbon black, pigments of the D & C type, lakes based on cochineal carmine, barium, strontium, calcium, aluminium or the diketopyrrolopyrroles (DPP).

The pigments used in the invention may be surface-treated with an organic agent.

The previously surface-treated pigments useful in the context of the invention are pigments that have undergone, fully or partially, a surface treatment of a chemical, electronic, electrochemical, mechanical-chemical or mechanical nature, with an organic agent such as those that are notably described in Cosmetics and Toiletries, February 1990, Vol. 105, p. 53- 64, before being dispersed in the compositions of the invention. These organic agents may for example be selected from amino acids; waxes, fatty acids, fatty alcohols and derivatives thereof, anionic surfactants; lecithins; sodium, potassium, magnesium, iron, titanium, zinc or aluminium salts of fatty acids; metal alkoxides; polysaccharides; polyethylene; (meth)acrylic polymers; polymers and copolymers containing acrylate units; proteins; alkanolamines; silicone compounds; fluorinated organic compounds; fluorosilicone compounds.

The surface-treated pigments useful in the invention may also have been treated with a mixture of these compounds and/or may have undergone several surface treatments. These surface-treated pigments may be prepared by surface treatment techniques that are well known by a person skilled in the art or they are commercially available as such.

Preferably, the surface-treated pigments are coated with an organic layer. The organic agent may be deposited on the pigments by solvent evaporation, chemical reaction between the molecules of the surface agent or creation of a covalent bond between the surface agent and the pigments.

Preferably, an organic agent bound covalently to the pigments will be used.

The composition may comprise at least one pigment in a content ranging from 0.01 to 25% by weight, notably from 0.1 to 15% by weight, and in particular from 1 to 10% by weight, relative to the total weight of the composition.

"Nacres" are to be understood as coloured particles of any shape, iridescent or not, notably produced in the shell of certain molluscs or else synthesized, and that display a colour effect by optical interference.

The nacres may be selected from the nacreous pigments such as titanium mica coated with an iron oxide, titanium mica coated with bismuth oxychloride, titanium mica coated with chromium oxide, titanium mica coated with an organic dye as well as the nacreous pigments based on bismuth oxychloride. They may also be mica particles, the surface of which is overlaid with at least two successive layers of metal oxides and/or organic colouring matter. We may also mention, as an example of nacres, natural mica coated with titanium oxide, iron oxide, natural pigment or bismuth oxychloride.

The nacres may more particularly possess a yellow, pink, red, bronze, orange, brown, gold and/or coppery colour or sheen.

"Dyes" are to be understood as compounds, generally organic, that are soluble in fats such as oils.

The fat-soluble dyes are for example Sudan Red, DC Red 17, DC Green 6, β-carotene, Sudan Brown, DC Yellow 11, DC Violet 2, DC Orange 5, quinoline yellow.

The composition used in the invention may also contain at least one material with a special optical effect.

This effect is different from a conventional simple tint effect, i.e. unified and stabilized such as produced by the classical colorants, for example the monochromatic pigments. In the sense of the invention, "stabilized" signifies lacking an effect of variability of the colour with the angle of observation or else in response to a temperature change.

For example, this material may be selected from particles with a metallic sheen, goniochromatic colouring agents, diffracting pigments, thermochromic agents, optical brighteners, as well as fibers, notably interference fibers.

The particles with a metallic sheen usable in the invention are in particular selected from:

- particles of at least one metal and/or of at least one metal derivative,

- particles comprising a substrate, organic or mineral, single-material or multi-material, coated at least partially with at least one layer with a metallic sheen comprising at least one metal and/or at least one metal derivative, and mixtures of said particles.

Among the metals that may be present in said particles, we may mention for example Ag, Au, Cu, Al, Ni, Sn, Mg, Cr, Mo, Ti, Zr, Pt, Va, Rb, W, Zn, Ge, Te, Se and mixtures or alloys thereof. Ag, Au, Cu, Al, Zn, Ni, Mo, Cr, and mixtures or alloys thereof (for example bronzes and brasses) are preferred metals.

"Metal derivatives" denotes compounds derived from metals, notably oxides, fluorides, chlorides and sulphides.

The goniochromatic colouring agent may be selected for example from multilayer interference structures and colouring agents with liquid crystals.

The composition may comprise at least one colorant in a content ranging from 0.01 to 50% by weight, preferably from 0.1 to 30% by weight, and more preferably from 1 to 20% by weight, relative to the weight of the composition Aqueous phase

The base composition and the finishing composition used in the cosmetic method or kit according to the invention may further each comprise an aqueous phase comprising water and optionally one or more hydrophilic gelling agents, with the water content ranging from 10 to 100% by weight, preferably from 15 to 70 % by weight, relative to the total weight of the composition.

The hydrophilic gelling agent may preferably be a hydrocolloid, which may notably be selected from: homo- and copolymers of acrylic acid and/or of salts or of esters of acrylic acid, such as carbomers, mixtures based on sodium polyacrylate; homo- and copolymers of acrylamide; homo- and copolymers of acryloylmethylpropane sulphonic acid (AMPS); associative polymers; polysaccharides such as guar gum or xanthan gum, carrageenans, grafted levanans and non-grafted inulins; and cellulose derivatives, but this is not an exhaustive list. The aqueous phase may also contain soluble silicone compounds.

Surfactants

The base composition and the finishing composition used in the cosmetic method or kit according to the invention may also comprise one or more surfactants, selected from water-in- oil or oil-in-water emulsifiers.

Active ingredients

The compositions used in the invention may in addition contain one or more hydrophilic or lipophilic active ingredients.

They may for example comprise an active ingredient for bleaching the skin, capable of blocking the synthesis of structural proteins involved in the mechanism of melanogenesis (stage I); a bleaching agent inhibiting melanin synthesis, and/or inhibiting MITF expression, and/or having anti-tyrosinase activity, and/or inhibiting the synthesis of endothelin-1; a bleaching agent having an antioxidant effect.

The compositions used in the invention may also contain an anti-ageing active ingredient, which may notably be selected from: agents stimulating the expression of tensin 1; agents stimulating the expression of fructosamine-3 -kinase or of its related protein (FN3K RP); agents stimulating the production of growth factors; anti-glycation or deglycating agents; agents that increase collagen synthesis or prevent its degradation (anti-collagenase agents, notably inhibitors of matrix metalloproteinases); agents that increase elastin synthesis or prevent its degradation (anti-elastase agents); agents that increase the synthesis of glycosaminoglycans or of proteoglycans or prevent their degradation (anti-proteoglycanase agents); agents that stimulate the synthesis of integrins by fibroblasts; agents that increase the proliferation or differentiation of keratinocytes; agents that increase the proliferation of fibroblasts; antioxidant or anti-radical or anti-pollution agents; and mixtures thereof, without this list being exhaustive.

The compositions used according to the invention may additionally contain humectants such as hyaluronic acid and the salts thereof and/or polyols such as glycerin. Usual additional cosmetic ingredients

The base composition and the finishing composition used in the cosmetic method or kit according to the invention may also comprise any usual cosmetic ingredient, which may notably be selected from antioxidants, perfumes, preservatives, neutralizing agents, surfactants, sun filters, vitamins, hydrating agents, self-tanning compounds, antiwrinkle agents, emollients, hydrophilic or lipophilic active ingredients, anti-free radical agents, deodorants, sequestering agents, film- forming agents, and mixtures thereof.

According to the cosmetic method of the invention it is also possible to apply a cosmetic or dermatological composition to the keratinous material prior the application of the base composition. An example of such a composition is a skin care composition.

The present invention is also directed to a continuous film obtainable with to the cosmetic method described above. In another embodiment, the invention is directed to the use of 1/ a base composition comprising a silicon-based product and an UV filter with 21 a finishing composition comprising a silicon-based product and an UV filter, said silicon-based products being capable of reacting together, in order to form a protecting film against UV radiation having a SPF value VT > VA + VB, VA being the SPF value of the base composition and VB being the SPF value of the finishing composition.

Another aspect of the invention is a kit for protecting keratinous materials, particularly the skin, against UV radiations comprising:

1/ a base composition comprising an UV filter, 21 a finishing composition comprising an UV filter,

wherein at least one of the base composition or the finishing composition comprises at least one compound chosen from:

- a silicon polymer A having silicon-bonded alkenyl groups called "Si-Alkenyl" groups, - a silicon polymer B having silicon-bonded hydrogens groups called "SiH" groups,

- a catalyst C,

and mixtures thereof,

with the proviso that:

said polymer A and polymer B being capable of reacting together by a hydrosilylation reaction in the presence of said catalyst C when they are contacted with one another.

The base composition and the finishing composition of the kit are as refined above.

Each composition present in the kit (i.e. the base and the finishing composition) is packaged separately.

The invention is also directed to the use of a kit as defined above in order to form, on the keratinous materials, a continuous protecting film against UV radiations.

The following examples are provided to illustrate the invention, and are not limitating. The percentages are expressed by weight relative to the total weight of each composition. The method used herein for the in vitro SPF measurement is conducted according to the

"IN VITRO METHOD FOR THE DETERMINATION OF THE UVA PROTECTION FACTOR AND "CRITICAL WAVELENGTH" VALUES OF SUNSCREEN PRODUCTS", prepared by the "COLIPA In vitro UV Protection Method Task Force", March 2011.

EXAMPLES

1) COMPOSITIONS USED IN THE INVENTION • Base composition n°l :

The finishing composition n° 2 has a SPF value VB = 24.

2) PROTOCOL AND RESULTS

The base composition n° 1 is applied and the finishing composition n° 2 is then applied over the base composition. A film is formed by reaction of the two compositions. The SPF of the formed film is measured.

The film has a measured SPF value of 57. It is thus observed that the film formed according to the method of the invention has a SPF value that is much higher than the sum of the SPFs of each of the base and finishing compositions (14 + 24). 3) COMPARATIVE EXAMPLES AND RESULTS

• Base composition 3 without any UV filter:

The base composition n°3 containing no UV filter and the finishing composition n°2 are applied according to the method of the invention disclosed in the protocol (point 2 above). The SPF value of the obtained film is 15. It is thus observed that the mixture of the two compositions unexpectedly leads to a decrease of the SPF value.

• Base composition n°l (SPF value

Zinc oxide & OTS-5 MZ-500 3 Triethoxycaprylylsilane (DAITO)

Titanium dioxide & Aluminum Miyoshade T-Clear 7 hydroxide & Stearic acid & Dimethicone (Miyoshi)

Dimethicone Belsil DM5 Dimethicone 10

Bis-vinyldimethicone (and) Silica silylate DC 7-FC4210 Elastomer (Part A) 50 (and) Platinum diviny ldisilo xane (Dow Corning)

Isododecane Isododecane 30 • Finishing composition 4 without any UV filter:

The base composition 1 and the finishing composition 4 containing no UV filter are applied according to the method of the invention disclosed in the protocol (point 2 above). The SPF value of the obtained film is 3. It is thus observed that the mixture of the two compositions unexpectedly leads to a decrease of the SPF value.

Claims

1. A method for protecting keratinous materials, particularly the skin, against UV radiations comprising applying successively, to the keratinous materials:

1/ a base composition comprising an UV filter,

21 a finishing composition comprising an UV filter,

- a catalyst C,

and mixtures thereof,

with the proviso that:

2. The method according to claim 1 , wherein:

- the silicon polymer A comprises at least two unsaturated aliphatic groups, and is more particularly selected from polyorganosiloxanes comprising siloxane units of the formula (I):

F R'SiOQ^) (I)

2

in which:

* m is 1 or 2 and,

* R' represents: • an unsaturated aliphatic hydrocarbon group containing 2 to 10, and preferably 3 to 5 carbon atoms, or

• an unsaturated cyclic hydrocarbon group containing 5 to 8 carbon atoms, and more preferably R' represents a vinyl group or a group— R"— CH=CHR"' in which R" is a divalent aliphatic hydrocarbon chain, linear or branched, containing 1 to 8 carbon atoms, which is bonded to the silicon atom, and R'" is a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, and preferably a hydrogen atom,

- the silicon polymer B is an organosiloxane comprising at least two free Si— H groups, and is more particulalry selected from organosiloxanes comprising at least one alkylhydrosiloxane unit of formula (III):

2

in which:

* R represents a monovalent, linear, branched or cyclic, hydrocarbon group containing 1 to 30 carbon atoms, and preferably R represents an alkyl radical containing 1 to

10 carbon atoms or R represents a phenyl group,

* p is 1 or 2,

and said organosiloxanes B comprising more particularly at least two alkylhydrosiloxane units of formula -(H₃C)(H)Si-0- and optionally comprise -(H₃C)₂SiO- units,

- the hydro silylation catalyst C is a platinum based catalyst or a rhodium based catalyst, and in particular a platinum complex stabilized by divinyltetramethyldisiloxane.

3. The method according to claim 1 or claim 2, wherein the ratio "Silicon polyi A: Silicon polymer B" is "1 : 1".

4. The method according to any one of claims 1 to 3, wherein the silicon polymer A and the catalyst C are present in the base composition and the silicon polymer B is present in the finishing composition.

5. The method according to any one of claims 1 to 3, wherein the silicon polymer B is present in the base composition and the silicon polymer A and the catalyst C are present in the finishing composition.

6. The method according to any one of claims 1 to 5, wherein the UV filter present in the base composition or in the finishing composition is a mineral sunscreen chosen from zinc oxide, titanium dioxide and their mixtures. 7. A continuous film obtainable with to the cosmetic method of any one of claims 1 to

6.

8. A kit for protecting keratinous materials, particularly the skin, against UV radiations comprising:

1/ a base composition comprising an UV filter,

21 a finishing composition comprising an UV filter,

- a catalyst C,

and mixtures thereof,

with the proviso that:

9. Use of a kit according to claim 8 in order to form, on the keratinous materials, a continuous protecting film against UV radiation.

10. Use of 1/ a base composition comprising a silicon-based product and an UV filter with 21 a finishing composition comprising a silicon-based product and an UV filter, said silicon-based products being capable of reacting together, in order to form a protecting film against UV radiation having a SPF value VT > VA + VB, VA being the SPF value of the base composition and VB being the SPF value of the finishing composition.