WO2005016301A1

WO2005016301A1 - Oily external phase solar emulsions

Info

Publication number: WO2005016301A1
Application number: PCT/FR2004/050375
Authority: WO
Inventors: Chantal Amalric; Alicia Roso; Nelly Michel; Guy Tabacchi
Original assignee: Societe D'exploitation De Produits Pour Les Industries Chimiques - Seppic
Priority date: 2003-08-07
Filing date: 2004-08-05
Publication date: 2005-02-24
Also published as: FR2858554B1; FR2858554A1; EP1675655A1

Abstract

The invention relates to a novel solar emulsion consisting of an external oily phase and two internal aqueous phases one of which is gelled and to a method for preparing said emulsion. Said oily and/or aqueous phases are provided with one or several solar fiiter(s).

Description

OIL EXTERNAL PHASE SOLAR EMULSIONS

The present invention relates to a new solar emulsion consisting of an oily external phase and two aqueous internal phases, as well as a process for the preparation of said emulsion. Technological background Solar emulsions must meet a certain number of criteria: they must have a sufficient photoprotective effect. This factor is quantified by measuring the capacity of a solar composition to reduce the erythema caused by ultraviolet radiation; it is desirable that they have water resistance properties, that is to say that once spread over the skin, they retain their photoprotective function as much as possible after swimming; for the comfort of the user, it is also desirable that the topical solar compositions have practical and sensory qualities. In particular, they should be easy to spread, should not cause a feeling of fat, or be sticky. A large number of sun compositions have been developed based on oil-in-water emulsions. With sufficient fatty phase, this type of emulsion has the advantage of facilitating the dissolution of sunscreens, which are for the most part lipophilic or lipodispersible organic compounds, and also makes it possible to achieve good sensory properties: soft feel and spreading. easy. The water resistance of oil-in-water emulsions is however low. It may therefore be necessary to add additives which "structure" or "stiffen" the aqueous phase, such as poly (vinylpyrrolidone), polyacr lates, polyacrylamides or even silicone oils which increase the water-repellent properties of the film obtained by spreading the emulsion. The addition of such additives is often harmful as regards the desired sensory properties. It has therefore been envisaged to formulate emulsions of the water-in-oil type. However, such emulsions have the disadvantage of being difficult to spread and are perceived as fatty on the sensory level. Summary of the invention The present inventors have discovered that the use of certain types of water-in-oil type emulsion makes it possible to satisfactorily meet all of the criteria mentioned above. It is in particular possible to combine a high level of photoprotection with a high resistance to water while retaining an acceptable spreadability and respecting other sensory parameters (non-greasy, non-sticky feel). The water-in-oil emulsions used in the present invention are formed by the addition of a water-in-oil type emulsion to an aqueous gel (or vice versa). Under these circumstances, a person skilled in the art generally expects to obtain a “water-in-oil-in-water” emulsion or a phase separation. However, the system according to the present invention makes it possible to obtain an emulsion with an oily external phase, having a fresh, pleasant and non-sticky texture. Thus, according to a first aspect, the invention relates to a solar emulsion consisting of an oily external phase and two aqueous internal phases, one of which is a gel, the oily phase comprising an emulsifying system, one or more solar filters. being incorporated in the oily phase and or in the gelled aqueous phase. Advantageously, the oil of the oily external phase represents at least 2% by weight, preferably from 5 to 20% by weight, and generally at most 50% by weight of the emulsion. According to a second aspect, the subject of the present invention is a process for preparing the emulsion described above, said process comprising mixing a “water-in-oil” emulsion (which will be called hereinafter “ primary emulsion with oily external phase "), itself obtained by dispersing the aqueous phase in the oily phase, and an aqueous gel. Advantageously, said mixture comprises 5 to 80% by weight, preferably 10 to 60% by weight of the primary emulsion with oily external phase, and 20 to 95% by weight, preferably 40 to 90% by weight of aqueous gel. In accordance with the process of the invention, it matters little whether the primary emulsion with oily external phase is introduced into the aqueous gel or the aqueous gel into the primary emulsion with oily external phase. However, it may be advantageous to add the primary emulsion with an oily external phase to the aqueous gel, preferably with moderate stirring. The process for the preparation of an emulsion according to the present invention makes it possible to obtain photoprotective solar emulsions having excellent resistance to water, that is to say making it possible to limit the reduction in protection (or the loss protection) of the user's skin against ultraviolet radiation after prolonged contact with water (bathing, showering, etc.), as well as improved processing properties: low-fat, easy emulsions to spread and not sticky.

Detailed description of the present invention The primary emulsion with oily external phase generally comprises from 5 to 90%, preferably 2 to 50%, by weight of oil. This oil can be selected from one or more of the following oils: - the vegetable oils such as sweet almond oil, coconut oil, mono ^"castor oil. , jojoba oil, olive oil, rapeseed oil, peanut oil, sunflower oil, wheat germ oil, corn germ oil, l soybean oil, cottonseed oil, alfalfa oil, poppy oil, pumpkin oil, evening primrose oil, millet oil, barley oil, l rye oil, safflower oil, bancoulier oil, passionflower oil, hazelnut oil, palm oil, shea butter, apricot kernel oil, l calophyllum oil, sysymbrium oil, avocado oil, calendula oil; - modified vegetable oils such as the products known under the names Apricot Kernel Oil PEG-6 esters, Olive Oil PEG-6 esters and LABRAFIL®; - oils of animal origin, such as squalene, squalane; - mineral oils, such as paraffin oil or petrolatum oil, and mineral oils, in particular from petroleum fractions, such as isoparaffins, having a boiling point between 300 and 400 ° C; - synthetic oils, in particular esters of fatty acids such as isodecyl neopentanoate, butyl myristate, propyl myristate, cetyl myristate, ethylhexyl cocoate, isopropyl palmitate, palmitate 2-ethylhexyl, butyl stearate, hexadecyl stearate, isopropyl stearate, octyl stearate, isoketyl stearate, propyl or isostearyl isostearate, decyl or stearate oleate dodecyl, hexyl laurate, propylene glycob dicaprylate esters derived from lanolic acid, such as isopropyl lanolate, isocetyl lanolate, monoglycerides, diglycerides and triglycerides of fatty acids such as glycerol triheptanoate, caprylic-capric triglyceride, diisopropyl or ethylhexyl adipate, neopentylglycol diheptanoate, diisopropyl or diethylhexyl sebacate, lauryl lactate or myristyle, diethylhexyl maleate; - other synthetic oils such as alkyl benzoates, isoparaffins, polyalphaolefins, polyolefins, such as polyisobutene, synthetic isoalkanes such as isohexadecane, isododecane, perfluorinated oils and silicone oils. Among the latter, mention may more particularly be made of dimethylpolysiloxanes, methylphenylpoly-siloxanes, silicones modified by amines, silicones modified by fatty acids, silicones modified by alcohols, silicones modified by alcohols and fatty acids, silicones modified by polyether groups, modified epoxy silicones, silicones modified by fluorinated groups, cyclic silicones and silicones modified by alkyl groups. This oil can also be chosen from fatty acids, fatty alcohols, waxes of natural or synthetic origin, and more generally still any fatty substance of vegetable, animal or synthetic origin. Preferably, one or more synthetic oils will be used, chosen from the group consisting of fatty acid esters such as isodecyl neopentanoate, butyl myristate, propyl myristate, cetyl myristate, isopropyl palmitate , 2-ethylhexyl palmitate, butyl stearate, hexadecyl stearate, isopropyl stearate, octyl stearate, isoketyl stearate, Dodecyl poleate, hexyl laurate, propylene glycol dicaprylate , esters derived from lanolic acid, such as isopropyl lanolate, isocetyl lanolate, monoglycerides, diglycerides and triglycerides of fatty acids such as glycerol triheptanoate and capric caprylic triglyceride, alkyl benzoate in Cι ₂ -Cι ₅ , diisopropyl adipate, ethylhexyl cocoate, diisopropyl or ethylhexyl adipate, diisopropyl or diethylhexyl sebacate, lauryl or myristyl lactate, dié maleate thylhexyle. The primary emulsion with an oily external phase also comprises from 0.1 to 25%, preferably 1 to 5%, by weight of an emulsifying system of lipophilic nature, comprising one or more emulsifying surfactants. Among the emulsifying surfactants capable of being used in the context of the present invention, mention will be made in particular of lipoamino acids and their salts; lipopeptides and their salts; sorbitan esters such as, for example, the product marketed under the name MONTANE® 80 by the company SEPPIC; mannitan and xylitan esters; polyglycerol esters such as for example the products sold under the name ISOLAN® GI34 by BASF and PLUROL® DIISOSTEARIQUE by GATTEFOSSE; ethoxylated castor oil and ethoxylated hydrogenated castor oil, for example the product sold under the name SIMULSOL® 989 by the company SEPPIC; glycerol stearate; polyglycol or polyglycerol polyhydroxystearates such as for example the products called HYPERMER® B246, ARLACEL® P135 marketed by the company UNIQEMA, the product called DEHYMUL-S® PGPH marketed by the company COGNIS, the product called DECAGLYN® 5HS marketed by the company NIKKO; polyethylene glycol-alkyl glycol copolymers such as PEG-45 dodecyl glycol copolymer such as the product sold under the name Elfacos ST 9 ^® by Akzo; ethoxylated sorbitan esters such as, for example, the products sold under the name MONTANOX® by the company SEPPIC; weakly ethoxylated protein acylates (from 1 to 3 ethylene oxide groups); ethoxylated beeswax, for example the product called APIFIL® sold by the company GATTEFOSSE; cationic emulsifiers such as aminoxides, polyquaternium 82 and the surfactants described in patent application WO 96/00719 and mainly those in which the fatty chain comprises at least 16 carbon atoms; sucrose esters, methylglucoside esters, ethoxylated or not; ethoxylated fatty acids; ethoxylated fatty alcohols; anionic emulsifiers such as decylphosphate or cetarylsulfate; aluminum polyoxystearate, such as for example the product sold under the name MANALOX® sold by the company RHOD1A; magnesium stearate; aluminum stearate. Non-ionic and anionic silicone emulsifying surfactants are also capable of being used in the context of the present invention. It is also possible to use emulsifying surfactants of the alkylpolyglycoside type, for example those described in patent applications FR-A-2668080, FR-A-2734496, FR-A-2762317, FR-A-2784904 and in the application FR-A-2790977, in particular xylose derivatives. It is also advantageous to use an emulsifier based on alkylpolyglycosides and fatty diols, comprising in particular: - 5 to 95 parts by weight of a mixture of alkylpolyglycosides consisting of the reaction products of a saccharide and a dimerdiol having 36 carbon atoms; - 95 to 5 parts by weight of a dimerdiol having 36 carbon atoms. The preferred emulsifiers, corresponding to the definition above, comprise: 5 to 60 parts by weight of the abovementioned mixture of alkylpolyglycosides; and - 95 to 40 parts by weight of dimerdiol having 36 carbon atoms. The mixture of alkylpolyglycosides consisting of the reaction products of a saccharide and a dimerdiol having 36 carbon atoms is in fact composed of a mixture in all proportions of hydroxyalkylpolyglycosides (products resulting from the acetalization of one of the two hydroxyl groups of dimerdiol) and polyglycosylalkylpolyglycosides

(products resulting from the acetalization of the two hydroxyl groups of dimerdiol). These alkylpolyglycosides can be represented, respectively by the following formulas I and II:

HO-RO (G) _n (I) (G) _m -OR-O- (G) _p (II) in which: G represents a saccharide residue; R represents a disubstituted group derived from dimeric alcohol derived from the hydrogenation of dimeric acid; n, m and p represent the average degree of polymerization of each saccharide residue. The product known under the name "dimeric acid" is a dibasic acid having 36 carbon atoms, the majority compound of which can be represented by the formula:

The abovementioned alkyl polyglycosides may contain, as the saccharide residue, a residue of glucose or dextrose, fructose, galactose, mannose, ribose, xylose, preferably a residue of glucose or xylose. It should also be noted that each unit of the polysaccharide part of the abovementioned alkyl polyglycosides can be in anomeric form α or β, and the rest of the saccharide can be of the furanoside or pyranoside type. The average degree of polymerization of each saccharide residue is generally between 1.05 and 2.5, more preferably between 1.1 and 2. The expression "alkylpolyglycoside" used in the context of the present application therefore designates either alkylmonooside (degree of polymerization equal to 1) or an alkylpolyglycoside (degree of polymerization greater than 1). The dimerdiol used for the preparation of the above emulsifying surfactant is a diol obtained from the hydrogenation of dimer acid. It is sold in particular by the COGNIS Company under the name SPEZIOL ^® C 36/2. This compound, due to its origin, may contain minor proportions of impurities. Such impurities can be present in amounts of up to 30% by weight of the total weight of the diol. Consequently, the emulsifying surfactants based on alkylpolyglycosides and fatty diols can comprise, in corresponding minor proportions, such impurities, or the reaction products of these impurities with a saccharide. The emulsifying surfactants based on alkylpolyglycosides and fatty diols which can be used in the context of the present invention can be prepared by simple mixing of their constituents in desired predetermined proportions. On an industrial scale, they will preferably be prepared according to one of the two routes conventionally used for the synthesis of alkylpolyglycosides, and for example by reaction, in an acid medium, between dimerdiol and a saccharide having an anomeric OH, such as glucose or dextrose. If necessary, this synthesis may be supplemented by operations of neutralization, filtration, distillation or partial extraction of excess fatty diol or discoloration. It may also be particularly advantageous to use an emulsifying surfactant based on alkylpolyxyloside, as described in application EP-A-1142901, of formula: RO- (X) _p in which: p represents a decimal number between 1 and 5, X represents the remainder of xylose, and R represents a branched alkyl radical: CH (C _n H _{2n +} ιXC _m H ₂ m _{+ l} ) -CH ₂ - in which m is an integer between 6 and 18, n is an integer between 4 and 18 and the sum n + m is greater than or equal to 14; or a composition consisting of a mixture of at least two compounds as defined above; or alternatively, in a preferred embodiment, a composition comprising: more than 0% by weight and less than 100% by weight, preferably from 1% to 60% by weight, of a compound or of a mixture of compounds defined above, and more than 0% by weight and less than 100% by weight, preferably from 40% to 99% by weight, of a compound or a mixture of compounds of formula ROH in which R a the meaning mentioned above In this embodiment, the compositions comprising an alkylpolyxyloside RO- (X) _p and its corresponding alcohol ROH, in the proportions indicated above, are particularly preferred. Advantageously, an emulsifying system is used which contains at least one emulsifying surfactant chosen from alkylpolyglycosides, alkylpolyglycoside and fatty alcohol compositions, esters of polyglycerols or polyglycols or optionally alkoxylated polyols such as polyhydroxystearates of polyglycols or optionally alkoxylated polyglycerols, polyethylene glycol-alkyl glycol copolymers. Even more advantageously, an emulsifying system is used containing a polyglycol polyhydroxystearate, an optionally alkoxylated polyol polyhydroxystearate, a polyglycerol ester, or a polyethylene glycol-alkyl glycol copolymer in combination with an alkylpolyglycoside or with an alkylpolyglycoside composition and fatty alcohols. The emulsions according to the present invention can contain up to 10% by weight of a co-emulsifier. Among the co-ulcers capable of being used in the context of the present invention, mention will be made in particular of lipoamino acids and their salts, lipopeptides and their salts, sorbitan and mannitan esters, ethoxylated hydrogenated castor oil, glycerol stearate, cationic emulsifiers such as for example aminoxides, quaternium 82, sucrose esters, methylglucoside esters, ethoxylated or not, ethoxylated fatty acids, ethoxylated fatty alcohols, anionic emulsifiers such as decylphosphate or cetarylsulfate . Nonionic and anionic silicone emulsifying surfactants can also be used as co-emulsifiers in the context of the present invention. The primary emulsion with oily external phase can also comprise a stabilizing agent. Among the stabilizing agents capable of being used in the context of the present invention, mention may be made of hydrogenated castor oil; vegetable or animal waxes such as, for example, beeswax, candellila wax and carnauba wax; stearic acid; silicas including hydrophobic silicas; polymers such as the products marketed under the name KRATON®; mineral waxes such as ozokerite; clays such as hectorite or bentonite; hydrophobic modified starches, for example the product sold under the name DRY FLOW PC®; hydrophobic methacrylates and polymethylmethacrylates such as the product sold under the name MICROPEARL MHB® or under the name POLYTRAP®. The primary emulsion with an oily external phase also advantageously comprises one or more mineral salts, such as for example magnesium chloride, magnesium sulfate or sodium chloride, in an amount ranging from 0.05% to 5% by weight, preferably between 0.1% and 2%. The solar emulsions according to the invention comprise a photoprotective system comprising one or more sun filters, which can be incorporated in the oily phase and / or in the aqueous phase (s). Generally, the secondary filter (s) is (are) incorporated in the oily phase, in the gelled aqueous phase or, advantageously, in each of these phases. However, it may also happen that the “non-gelled” aqueous phase of the emulsion comprises one or more water-soluble or water-dispersible sun filters. When the gelled aqueous phase of the emulsion comprises (s) sunscreen (s), this (these) is (are) generally directly dispersed in the gelled aqueous phase if it ( s) is (are) liquid (s) or, sl ^ s) is (are) solid (s), it (s) is (are) generally previously dispersed (s) in a solvent such as ethanol or in a another liquid sunscreen which dissolves it before being incorporated into the aqueous gel. Sunscreens can be organic or inorganic in nature, and it is possible to combine organic and inorganic filters in one sunscreen emulsion. Among the organic filters, one can distinguish the family of benzoic acid derivatives such as para-aminobenzoic acids (PABA), in particular the monoglycerol esters of PABA, the ethyl esters of N, N-propoxy PABA, the ethyl esters of N, N-diethoxy PABA, ethyl esters of N, N-dimethyl PABA, methyl esters of N, N-dimethyl PABA, butyl esters of N, N-dimethyl PABA; the family of anthranilic acid derivatives such as homomenthyl-N-acetyl anthranilate; the family of salicylic acid derivatives such as amyl salicylate, homomenthyl salicylate, ethylhexyl salicylate, phenyl salicylate, benzyl salicylate, p-isopropanolphenyl salicylate; the family of cinnamic acid derivatives such as ethylhexyl cinnamate, ethyl-4-isopropyl cinnamate, methyl-2,5-diisopropyl cinnamate, p-methoxypropyl cinnamate, p-methoxyisopropyl cinnamate , p-methoxyisoamyl cinnamate, p-methoxyoctyl cinnamate (p-methoxy 2-ethylhexyl cinnamate), p-methoxy 2-ethoxyethyl cinnamate, p-methoxycyclohexyl cinnamate, ethyl-α cinnamate -cyano-β-phenyl, 2- ethylhexyl- - cyano-β-phenyl cinnamate, glyceryl diparamethoxy mono-2-ethylhexanoyl cinnamate; the family of benzophenone derivatives such as 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2 ', 4,4'- tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4-phenylbenzophenone, 2-ethylhexyl-4 ' -phenylbenzophenone-2-carboxylate, 2-hydroxy-4-n-octyloxybenzophenone, 4-hydroxy-3-carboxybenzophenone; 3- (4'-methylbenzylidene) -d, 1-camphor, 3- (benzylidene) -d, 1-camphor, benzalkonium methosulfate camphor; urocanic acid, ethyl urocanate; the family of sulfonic acid derivatives such as 2-phenylbenzimidazole-5 sulfonic acid and its salts; the family of triazine derivatives such as hydroxyphenyl triazine, ethylhexyloxyhydroxyphenyl-4-methoxyphenyltriazine, 2,4,6-trianillino- (p-carbo-2 'ethylhexyl-l'-oxy) -1, 3,5 -triazine, 4,4 - ((6 - (((1,1-dimethylethyl) amino) carbonyl) phenyl) amino) -1,3,5-triazine-2,4-diyl diïmino) bis- (2- ethylhexyl) ester of benzoic acid, 2-phenyl-5-methylbenzoxazole, 2,2'-hydroxy-5-methylphenylbenzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2 - (2'-hydroxy-5'-methyphenyl) benzotriazole; dibenzazine; dianisoylmethane, 4-methoxy- 4 "-t-butylbenzoylmethane; 5- (3,3-dimethyl-2-norbornylidene) -3-pentan-2-one; the family of diphenylacrylate derivatives such as 2-ethylhexyl- 2-cyano-3,3-diphenyl-2-propenoate, ethyl-2-cyano-3,3-diphenyl-2-propenoate; the family of polysiloxanes such as benzylidene siloxane malonate. Among inorganic filters, also called "Mineral screens" can be distinguished from titanium oxides, zinc oxides, cerium oxide, zirconium oxide, yellow, red or black iron oxides, chromium oxides. These mineral screens can be micronized or not, having undergone or not surface treatments and possibly being presented in the form of aqueous or oily pre-dispersions The primary emulsions with oily external phase in accordance with the present invention can be prepared by simple dispersion, at a temperature comprised between 15 ° C and 90 ° C, of the aqueous phase in the ph oily, in the presence of the emulsifying surfactant (s), and optionally of the stabilizing ingredient (s). In a manner known per se, these emulsions may further comprise one or more compounds chosen from humectants, such as for example glycerin, glycols, the sodium salt of 5-carboxylic acid of 2-pyrrolidone, preservatives such as for example the products known under the name SEPICIDE®, dyes, perfumes, cosmetic active agents such as for example vitamins and derivatives of water-soluble vitamins, vitamins and derivatives of liposoluble vitamins, oligosaccharides, proteins, polypeptides, amino acids, N-acylated derivatives of amino acids and / or polypeptides and / or proteins, plant extracts, seaweed extracts, mineral salts, fillers minerals such as talc, mica, silica, sericite, synthetic texture-modifying fillers such as nylons and poly (methyl methacrylate) crosslinked or not, silicone elastomers. These compounds may be introduced into the aqueous phase or into the oily phase, depending on their affinity for these phases, either during the abovementioned dispersion phase, or as regards the temperature-sensitive compounds, subsequently during the phase cooling in the case where the dispersion is carried out hot. As previously specified, the primary emulsion with oily external phase can be added to the aqueous gel or vice versa. The aqueous gel is obtained by gelling an aqueous phase with a polymer, preferably of the polyelectrolyte type. Said polymer is advantageously present in an amount between 0.02 and 10% by weight, preferably between 0.4 and 8% by weight of the aqueous gel. Among the polymers capable of being used in the context of the present invention for gelling (thickening) the aqueous phase, mention will be made in particular of homopolymers or copolymers of acrylic acid, of acrylic acid derivatives, of acrylamide, of acrylamidomethanepropanesulfonic acid, vinyl monomer, or trimethylaminoethylacrylate chloride, such as for example the products sold under the name CARBOPOL®, PEMULEN®, SIMULGEL®A, SIMULGEL ®NS, SIMULGEL®EPG, SIMULGEL®EG, LUVIGEL®EM, SALCARE® SC91, SALCARE®SC92, SALCARE®SC95, SALCARE®SC96, FLOCARE®ET100, HISPAGEL®, SEPIGEL®305, SEPIGEL®501, SEPIGEL®502, FLOCARE®ET58, STABILEZE®06; hydrocolloids of plant or biosynthetic origin such as, for example, xanthan gum, karaya gum, carrageenans, alginates; silicates; cellulose and its derivatives; starch and its hydrophilic derivatives. Preferably, one or more polymers such as homopolymers and copolymers containing acrylamidomethanepropanesulfonic acid and its salts, acrylic acid and its salts and its derivatives, acrylamide and its derivatives will be used. The aqueous gel has a viscosity greater than 2 Pa.s (2000 cPs), preferably greater than 20 Pa.s (20,000 cPs), measured on a BROOKFIELD LV viscometer 6 rpm. The resulting emulsion, consisting of an oily external aqueous phase and two internal aqueous phases, one of which is a gel, comprises from 1 to 40% of sun filters by weight of the emulsion, preferably between approximately 2% and about 35%, and even more preferably between 5% and 25% by weight of the emulsion. The invention is illustrated by the following examples, given purely by way of indication.

EXAMPLES General protocol for the preparation of emulsions according to the present invention The preparation of solar emulsions according to the present invention can be carried out according to the following procedure: a) an oily phase "A" is prepared comprising the oil (s), the lipophilic emulsifying system, and optionally the co-emulsifier. These ingredients are mixed and then the resulting oily phase is brought to 50 ° C. One or more sun filter (s) are then added to this heated oily phase; this phase may possibly contain lipodispersible mineral screens. b) an aqueous phase "B" is prepared, in parallel with preparation (a) above, containing water, one or more mineral salt (s), and optionally glycerin as a humectant . This phase is also brought to 50 ° C; this phase may optionally contain water-soluble sunscreens or water-dispersible mineral screens. c) a primary emulsion "C" with an oily external phase is formed by mixing the aqueous phase "B" in the oily phase "A" while maintaining sufficient stirring until complete cooling; d) an aqueous gel "D" is separately formed by dispersing one or more thickening polymer (s) in water, which may also contain preservatives and perfumes; e) if necessary, one or more solaire filter (s) previously dispersed can be added so as to constitute a liquid phase and then this solution is added to the aqueous gel “D”; if this (these) filter (s) is (are) solid (s), ethanol or another liquid filter can be used to dissolve it (s) before the addition; f) the emulsion is incorporated into the gel (or the gel into the emulsion) with moderate stirring.

Depending on the scenario of the solar emulsion to be prepared, some of the steps (a) to (f) described above can be either modified or deleted. The temperatures to which the oily "A" and aqueous "B" phases are brought before their mixing can also be adapted as a function of the physicochemical characteristics of the sun filters to be incorporated. General protocols for measuring the properties of solar emulsions Determination of SPF (sun protection factor)

The sun protection index (PI) or sun protection factor (SPF) is defined as being equal to the ratio of the minimum erythemal dose obtained using a photoprotective product (DEMp) to the minimum erythemal dose without product (DEMnp), according to the following calculation:

FPS = DEMp / DEMnp The DEM, expressed in milliljoules, corresponds to the smallest light energy resulting in a perceptible and homogeneous erythema, with clear contours.

Under normal conditions of a test to assess the SPF, volunteers invited to the laboratory read an information sheet reminding them of the conditions of the test before signing a consent form. Colorimetric measurements are first carried out on the sites to be irradiated using a device such as the MINOLTA Chromameter®. Indeed, the type of skin must be determined, because the result of the test is very dependent on the color of the subject's skin. Skin types are divided into six categories, type 1 corresponding to the whitest skin encountered, which burns after exposure to the sun and which does not tan at all. Type 6 corresponds to the darkest skin tones, people with this phototype (generally of African origin) having skin that (almost) never burns. Preferably, subjects of phototypes II and III are chosen which are the most representative of the phototypes subject to a significant increase in erythema by ultraviolet radiation. Then ^" the sunscreen product is applied to the area to be irradiated at a rate of 2 mg / cm ^2. Control products standardized by the COLIPA (European Cosmetic Toiletry and Perfumery Association) are systematically tested simultaneously and make it possible to control the quality of the handling. Fifteen minutes after applying the products to the volunteer's skin, the affected areas are irradiated using a Xenon lamp following a geometric progression of 1.25, according to the supposed index of the product and the reference The Xenon lamp can for example be an IDEM 3000® Arquantiel short arc lamp, irradiating on a spectrum ranging from 290 to 400 nm. The infrared rays are filtered using a filter of type UG11 (1 mm). , and the elimination of IR is also carried out thanks to a water filter and ventilation. The irradiation surface is at least 1 cm ^2. The emitter power is approximately 1000 W. A typical system c has six openings with independent shutters. The successive opening of each orifice at a time interval fixed by the operator makes it possible to obtain a geometric progression (r = 1.25) of the UV dose received by the volunteer. At a time between 16 and 24 hours after the irradiation, the unprotected Minimum Erythemal Dose (DEMnp) and the DEMs protected by the reference and by the product are read simultaneously.

Determination of the water resistance of solar compositions The persistence of a solar product is studied by UV irradiation after a water resistance test. This test consists in taking the volunteers two baths at 30 ± 2 ° C for 20 minutes with a ten-minute break between each bath ("standardized bath"). The first bath is taken 15 minutes after applying the solar composition to be tested. The percentage of remanence is calculated according to the following formula;

% remanence = FPSwr / FPS x 100 with: FPS = Dry protection index FPS _wr = Protection index determined after the water resistance test It is generally considered that products with a percentage of persistence of less than 50% cannot be characterized as being resistant to water. 'water. A percentage of persistence between 50% and 80% corresponds to an acceptable degree of water resistance for a solar product. On the other hand, solar compositions having a percentage of persistence greater than or equal to 80% (and which therefore have a “high resistance” to water) are particularly sought in the context of the present invention.

Sensory evaluation The sensory evaluation was carried out using a panel of experts (typically a jury of 20 people), who rated the following criteria on a scale ranging from 0 to 10:

Ease of spreading: very easy = 10 very difficult = 0

Fat feeling: very fat = 10 no feeling of fat = 0

Sticky effect: very sticky = 10 no sticky effect = 0

Examples of making solar emulsions Example 1 and comparative examples 1 to 3

A solar emulsion having the composition indicated in Example 1 was prepared according to the general protocol indicated above. The photoprotection index and the percentage of persistence with respect to water were determined according to the protocols mentioned in the previous section. Subsequently, the sensory evaluation was carried out through a panel of experts. In parallel, comparative examples were carried out under conditions giving rise to an oil-in-water gel-cream (obtained without an emulsifying system), or to emulsions consisting of an oily external phase and a single aqueous internal phase. The comparative results are presented in Table 1. Table 1

(1) T100T SUNSMART (2) Z COTE HP1 TAYCA (3) alkylpolyxyloside on 2-octyldodecanol, prepared according to EP-A-1142901

It is found that only the emulsion according to the present invention (Example 1) combines water resistance performance with great ease of spreading, a non-greasy feel and an absence of tacky effect, with a similar photoprotection index. to that of Comparative Example 3, which translates knowledge of the state of the art for producing water-in-oil emulsions stabilized by the presence of microcrystalline waxes and not implementing the method according to the present invention.

Example 2 The solar emulsion is this time produced with the following components:

1. FLUIDANOV® 20X 2% 2. PEG30 dipolyhydroxystearate 0.5% 3. Cι ₂ -Cι ₅ alkyl benzoate 5% 4. Water 5% 5. Magnesium sulfate heptahydrate 0.02% 6. Glycerin 1.5% 7. Titanium oxide UV TITAN M160 10% 8. SIMULGEL S 2% 9. Water qspl00% 10. Ethanol 15% 11. Ethylhexyl methoxycinnamate 7 , 5% 12. Benzophenone-3 2.5% 13. Ethylhexyl salicylate 5% 14. Additives: preservatives, perfume qs

Ingredients 1 to 3 are mixed and brought to 50 ° C. The ingredient 7 is added and then a primary emulsion is formed with the aqueous phase 4 + 5 + 6 also brought to 50 ° C. A gel is then formed with 8 + 9 and separately 11 + 12 + 13 is dissolved in 10. This phase is added to the gel. Then the primary emulsion is also added to the gel. Finally, an IP35 solar emulsion is obtained which has a water resistance index of 90%. This emulsion is light, non-greasy, non-sticky and very easy to spread. It is very easy to develop and has only 5% oil; the organic filters are dissolved in hydroalcoholic gel and the mineral fillers are dispersed in the primary emulsion w / h.

The sensory evaluation gave the following notes: Ease of spreading: 9 Sensation of fat: 1 Sticky effect: 2

Example 3 and Comparative Example 4 The aim here is to compare emulsions according to the invention, prepared according to the procedure of Example 1, with a similar composition but not doped with lipophilic surfactants. This reference system commonly called gel-cream is very widespread on the cosmetic care market because it has sought-after sensory characteristics. It is however not widespread in solar applications due to its low resistance to water. The reformulation of these gels-creams with the method according to the present invention, and by using a lipophilic surfactant system, makes it possible to correct weak points and obtain formulations combining photoprotective performance, water resistance and pleasant sensory characteristics.

Table 2

EXAMPLE 4 AND COMPARATIVE EXAMPLE 5 The procedure of Example 3 and Comparative Example 4 is repeated, but with an oily phase of different structures and a filtering system of a mineral nature. Table 3

The method according to the invention makes it possible to incorporate a mineral filtering system with a gelling step of the aqueous phase, in order to achieve a water-in-oil emulsion, while stabilization proves impossible after gelling of the aqueous phase, in the oil-in-water scheme, without a surfactant system as in the present invention.

General conclusion The process for preparing solar emulsions of the present invention makes it possible: • to obtain photoprotective formulas having excellent water resistance, comparable to the traditional w / o emulsions of the prior art; Advantageously, these emulsions have very interesting sensory characteristics and similar to formulations of the gel-cream type. These latter formulations are very little present in the solar field because they are not very compatible with mineral screens, not very effective in photoprotection, and not resistant to water.

Claims

1. Solar emulsion, characterized in that it consists of an oily external phase and two aqueous internal phases, one of which is a gel, the oily phase comprising an emulsifying system, and the oily phase and / or the phase aqueous gel comprising one or more sun filters.

2. Emulsion according to claim 1, in which the oil of the oily external phase represents at least 2% by weight, preferably from 5 to 20% by weight, and at most 50% by weight, of the emulsion.

3. Emulsion according to claim 1 or 2, in which the emulsifying system comprises at least one emulsifying surfactant chosen from alkylpolyglycosides, compositions of alkylpolyglycosides and fatty alcohols, esters of polyglycerols or polyglycols, esters of polyols optionally alkoxylates such as polyhydroxystearates of polyglycols or of polyglycerol, optionally alkoxylated, or polyethylene glycol-alkyl glycols.

4. Emulsion according to one of claims 1 to 3, in which the emulsifying system comprises a polyglycol ester, an optionally alkoxylated polyol ester, a polyglycerol ester, or a polyethylene glycol-alkyl glycols copolymer in combination with an alkylpolyglycoside or a composition alkylpolyglycoside and fatty alcohol.

5. Emulsion according to one of claims 1 to 4, in which the aqueous gel is obtained by gelling an aqueous phase with a polymer.

6. An emulsion according to claim 5, wherein said polymer is present in an amount between 0.02 and 10% by weight, preferably between 0.4 and 8% by weight of the aqueous gel.

7. Emulsion according to one of claims 1 to 6, in which the aqueous gel has a viscosity greater than 2 Pa.s, preferably greater than 20 Pa.s, measured at Brookfield LV 6 rpm.

8. Emulsion according to one of claims 1 to 7, in which the sunscreen or filters represent approximately 2% to approximately 40%, preferably approximately 5% to approximately 20% by weight of the emulsion.

9. Emulsion according to one of claims 1 to 8, in which the oily phase further comprises one or more mineral fillers.