FR2852257A1 - Water-in-oil emulsion containing gelled aqueous phase, useful as cosmetic, pharmaceutical, veterinary or detergent compositions, where the aqueous phase includes a polyelectrolyte polymer - Google Patents

Abstract

Emulsion (A) comprises an external fat phase (P1) and a gelled aqueous phase (P2), with P2 being 60-98% of total. The new features are that P2 contains a polyelectrolyte polymer (I) and P1 comprises one or more oils (II) and a lipophilic emulsifier system comprising one or more emulsifying surfactants (III). An independent claim is also included for preparation of (A).

Description

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 The subject of the present invention is water-in-oil type emulsions with a high aqueous content, their preparation process and their uses.

Technological background
The emulsions make it possible to convey both water-soluble and liposoluble substances and therefore find particular application in the cosmetic, pharmaceutical and veterinary fields, and in the field of detergents.

 In the cosmetic field, there is a requirement on the part of the user of products in the form of emulsions to have emulsions which have appropriate sensory characteristics. Emulsions that provide a feeling of freshness and are felt in application to the skin as non-sticky are particularly sought after.

 The emulsions are classified according to the nature of the continuous phase (also called "external phase"), in which are dispersed droplets of the other phase (called "internal phase").

 In the case where the oil droplets are dispersed in an aqueous continuous phase, the system is called an "oil-in-water" (O / W) emulsion.

 In the case where the water droplets are dispersed in an oily continuous phase, the emulsion is of the "water-in-oil" (W / O) type.

 In general, among these two types of emulsions, it is easier to manufacture oil-in-water (O / W) emulsions because E / H emulsions are inherently thermodynamically unstable. Indeed, if we mix equal amounts of water and oil, we always observe the formation of an aqueous continuous phase emulsion, because the cohesive forces between water molecules are stronger than those between molecules. oil.

 However, oily continuous phase (W / O) emulsions have many advantages: - the separation between the water droplets reduces the possibility of proliferation of microorganisms. The use of antiseptics, essential when the continuous phase is aqueous, can be avoided; they are well conserved at low temperature, being much less sensitive in this respect than emulsions of the O / W type; - The oily continuous phase covers the skin and protects it from dehydration and against external substances.

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 In the development of an oily continuous phase emulsion system, two types of modifications have been envisaged: mechanical modifications concerning the combination of phases (phase addition order, flow control during combination of phases, phase temperature, stirring speed, etc.); - changes in the chemical components resulting in the stabilization of the emulsion.

 With regard to the mechanical modifications, the operating protocols used to prepare W / O generally require: a) a large energy supply, in the form of thermal activation (the aqueous and fatty phases are typically heated to 80 C), which must sometimes be followed by a gradual cooling well controlled; and / or b) the creation of turbulence in the biphasic medium to be emulsified (high stirring speed (thousands of revolutions per minute) and large shear caused by specific geometries of the stirrers).

 As regards the chemical modifications, mention may be made of: a) the use of microcrystalline waxes, such as ozokerite, which absorb the oil and prevent its exudation; b) the use of liquid paraffins as fat phase, since these are easier to emulsify; c) the addition of inorganic salts such as in particular sodium chloride or magnesium chloride, to increase the cohesion of the interfacial film.

 US-5746945 discloses water-in-oil emulsions which are stabilized by an emulsifier system having two components: a) a polysiloxane polyalkyl polyether copolymer and b) a phthalic anhydride derivative (a monoamide). The method of preparing emulsions in this document consists of the gradual addition of the aqueous phase to the oily phase. The two phases are each independently heated to 160 to 165 F (71 to 74 ° C) before being combined to obtain the emulsion.

 WO-97/40814 describes W / O emulsions intended in particular for use in impregnating baby wipes. The organic phase of the emulsions necessarily contains a wax. The emulsifiers used are of carboxylic acid type, substituted with hydrocarbons, or "block" ABA copolymers, involving monomers such as 12-hydroxystearic acid and ethylene.

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 glycol, or an alkyldimethicone copolyol. With regard to the process used to prepare the emulsions, the fatty phase and the aqueous phase are typically heated to 160 F (71 ° C) and then mixed at this temperature to obtain the emulsion.

 The typical procedures of the prior art therefore have a number of disadvantages, particularly related to the need to provide a significant energy intake to achieve the emulsion.

 A problem to be solved therefore consists in providing W / O emulsions with a high aqueous content, which have in particular a fresh and non-sticky texture.

 Another problem to be solved is to have a method of preparing such emulsions, which is: simple, that is to say that the number of steps implemented is reduced and that factors such as the control exact flow rates of introduction phases are not critical for the proper functioning of the process, and economic, that is to say, it does not require to spend a lot of energy or to heat the phases to combine or in the vigorous agitation to be provided during the preparation of the emulsion.

Summary of the invention
It has now been discovered, and it is the basis of the present invention, that by adding an oily phase to a gelled aqueous phase, it is possible to obtain W / O emulsions having the aforementioned characteristics, without thermal input and important mechanics.

 According to a first aspect, the present application therefore relates to an emulsion consisting of an oily external phase and a gelled aqueous phase, said aqueous phase representing from 60 to 98% by weight, preferably from 80 to 98% by weight. of the composition, characterized in that: the aqueous phase comprises a polyelectrolyte polymer whose ionic sites are associated with their counterions, and the oily phase comprises one or more oils and an emulsifying system of lipophilic character comprising one or more emulsifying surfactants.

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 According to a second aspect, the present application relates to a process for preparing a water-in-oil emulsion having a high aqueous content, comprising the following steps: a) preparing a fatty phase comprising one or more oils in the presence of a lipophilic emulsifying system comprising one or more emulsifying surfactants; b) a gelled aqueous phase containing a polyelectrolyte-type polymer is prepared independently of the fatty phase; c) the fatty phase is added to the aqueous phase.

 According to a third aspect, the present application relates to cosmetic, pharmaceutical, veterinary or detergent preparations containing an emulsion as defined above.

Detailed description of the present invention
According to the process of the invention, a fatty phase comprising, firstly, one or more oils chosen in particular from: oils of vegetable origin, such as sweet almond oil, coconut oil, castor oil, jojoba oil, olive oil, rapeseed oil, peanut oil, sunflower oil, wheat germ oil, corn sprouts, soybean oil, cottonseed oil, alfalfa oil, poppy oil, pumpkin oil, evening primrose oil, millet oil, oil of barley, rye oil, safflower oil, bancoulier oil, passionflower oil, hazelnut oil, palm oil, shea butter, kernel oil apricot, calophyllum oil, sysymbrium oil, avocado oil, calendula oil; vegetable oils and their ethoxylated methyl esters; oils of animal origin, such as squalene, squalane; mineral oils, such as paraffin oil, liquid petroleum jelly and isoparaffins; synthetic oils, in particular esters of fatty acids such as butyl myristate, propyl myristate, cetyl myristate, isopropyl palmitate, butyl stearate, hexadecyl stearate, stearate, isopropyl, octyl stearate, isocetyl stearate, dodecyl oleate, hexyl laurate, propylene glycol dicaprylate, esters derived from lanolic acid, such as isopropyl lanolate, lanolate isocetyl, monoglycerides, diglycerides and triglycerides of fatty acids such as glycerol triheptanoate, alkylbenzoates, polyalphaolefins, polyolefins such as polyisobutene, isoalkanes of

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 synthesis such as isohexadecane, isododecane, perfluorinated oils and silicone oils. Among these, mention may be made more particularly of dimethylpolysiloxanes, methylphenylpolysiloxanes, silicones modified with amines, silicones modified with fatty acids, silicones modified with alcohols, silicones modified with alcohols and fatty acids, silicones. modified with polyether groups, modified epoxy silicones, silicones modified with fluorinated groups, cyclic silicones and silicones modified with alkyl groups.

 The water-in-oil emulsion generally comprises from 2 to 40% by weight, preferably from 2 to 20% by weight, of oil (s).

 The fatty phase is prepared in the presence of an emulsifying system of lipophilic nature, comprising one or more emulsifying surfactants.

 Among the emulsifying surfactants that may be used in the context of the present invention, mention may in particular be made of lipoamino acids and their salts; lipopeptides and their salts; sorbitan esters, for example the product marketed under the name MONTANE 80 by the company SEPPIC; polyglycerol esters, 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 marketed under the name SIMULSOL 989 by the company SEPPIC; glycerol stearate; polyglycol or polyglycerol polyhydroxystearates, for example the products known as HYPERMER B246, ARLACEL P135 sold by the company UNIQEMA, the product called DEHYMULS PGPH marketed by the company COGNIS, the product called DECAGLYN 5HS marketed by 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 the company AKZO, ethoxylated sorbitan esters, for example the products sold under the name MONTANOX by the company SEPPIC; acylates of low ethoxylated proteins (from 1 to 3 EO groups); ethoxylated beeswax such as the product called APIFIL marketed by the company GATTEFOSSE; cationic emulsifiers such as aminoxides, quaternium 82 and the surfactants described in patent application WO 96/00719 and mainly those whose fatty chain comprises at least 16 carbon atoms; sucrose esters, ethoxylated or non-ethoxylated methylglucoside esters; ethoxylated fatty acids; ethoxylated fatty alcohols; emulsifiers

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Anionic compounds such as decyl phosphate or cetearyl sulphate; aluminum polyoxystearate, such as, for example, the product sold under the name MANALOX sold by Rhodia; magnesium stearate; aluminum stearate.

 Nonionic and anionic silicone emulsifying surfactants are also likely to be used in the context of the present invention, even if for practical reasons (they may cause a change in the sensory properties of the emulsions obtained), they do not represent an aspect preferred embodiment of the invention.

 It is also possible to use emulsifying surfactants of alkylpolyglycoside type, for example those described in patent application FR-A-2 790 977, in particular xylose derivatives.

 It is also advantageous to use an emulsifier based on alkylpolyglycosides and on fatty diols, especially comprising: 5 to 95 parts by weight of a mixture of alkylpolyglycosides consisting of the reaction products of a saccharide and a dimerdiol having carbon atoms; 95 to 5 parts by weight of a dimerdiol having 36 carbon atoms.

 Preferred emulsifiers as defined above include: 5 to 60 parts by weight of the above 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 constituted by a mixture in all proportions of hydroxyalkylpolyglycosides (products resulting from the acetalization of one of the two hydroxyl groups of dimerdiol) and of polyglycosylalkylpolyglycosides (products resulting from the acetalization of the two hydroxyl groups of dimerdiol).

These alkylpolyglycosides can be represented by the following formulas I and II, respectively:
HO-RO (G) n (I) (G) m-OR-O- (G) p (II) in which:
G represents a saccharide residue;

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R represents a disubstituted group derived from the dimeric alcohol from the hydrogenation of the dimer acid; n, m and p represent the average degree of polymerization of each saccharide residue.

The product known under the name "dimer acid" is a dibasic acid having 36 carbon atoms, the majority compound of which can be represented by the formula:

The alkylpolyglycosides mentioned above may comprise, as saccharide residue, a residue of glucose or dextrose, fructose, galactose, mannose, ribose, xylose, preferably a glucose or xylose residue.

 It should further be noted that each unit of the polysaccharide portion of the aforementioned alkylpolyglycosides may be in the anomeric form a or ss, and the saccharide residue may 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 term "alkylpolyglycoside" used in the context of the present application thus denotes either an alkylmonoside (degree of polymerization equal to 1) or an alkylpolyglycoside (degree of polymerization greater than 1).

 The dimerdiol used for the preparation of the emulsifying surfactant above is a diol derived from the hydrogenation of the dimer acid.

 It is marketed by the company COGNIS under the name SPEZIOL # C 36/2.

 This compound, because of its origin, may contain minor proportions of impurities. Such impurities may be present in amounts up to 30% by weight of the total weight of diol.

 Therefore, emulsifying surfactants based on alkylpolyglycosides and fatty diols may comprise, in corresponding minor proportions, such impurities, or the reaction products of these impurities with a saccharide.

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 The emulsifying surfactants based on alkyl polygon lycosides and fatty diols that may be used in the context of the present invention may be prepared by simply mixing their constituents in predetermined 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 anomeric OH, such as than glucose or dextrose.

 If necessary, this synthesis may be completed by operations of neutralization, filtration, distillation or partial extraction of the excess fatty diol or discoloration.

It may also be particularly advantageous to use an alkylpolyxyloside emulsifying surfactant, as described in application EP-A-1142901, of formula: RO- (X) p in which: p represents a decimal number of between 1 and 5,
X represents the rest of the xylose, and
R represents a branched alkyl radical:
CH (CnH2n + 1) (CmH2m + 1) -CH2- wherein m is an integer from 6 to 18, n is an integer from 4 to 18 and the sum n + m is greater than or equal to 14; or, in a particularly preferred embodiment, a composition consisting of a mixture of at least two compounds as defined above; or else 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 a mixture of compounds defined above and more than 0% by weight. % 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 wherein R has the meaning mentioned above.

 Particularly advantageously, a mixture of alkylpolyxyloside R-O- (X) p and its corresponding alcohol ROH is used, in the proportions indicated above.

 Advantageously, an emulsifying system containing at least one emulsifying surfactant chosen from alkylpolyglycosides,

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 compositions of alkylpolyglycosides and fatty alcohols, esters of polyglycerols or polyglycols or polyols such as polyhydroxystearates of polyglycols or polyglycerols.

 Even more advantageously, an emulsifier system containing a polyol polyhydroxystearate or a polyglycerol ester is used in combination with an alkylpolyglycoside and fatty alcohol composition.

 The emulsions according to the present invention may contain up to 10% by weight of a co-emulsifier.

 Among the co-emulsifiers that may be used in the context of the present invention, mention may in particular be made of lipoamino acids and their salts, lipopeptides and their salts, sorbitan esters, polyglycerol esters, ethoxylated hydrogenated castor oil , glycerol stearate, cationic emulsifiers, for example aminoxides, quaternium 82, sucrose esters, ethoxylated or non-ethoxylated methylglucoside esters, ethoxylated fatty acids, ethoxylated fatty alcohols, anionic emulsifiers such as decylphosphate or cetearylsulfate.

 Nonionic and anionic silicone emulsifying surfactants may also be used as co-emulsifiers in the context of the present invention, even if for practical reasons (they may cause a change in the sensory properties of the emulsions obtained), they do not represent a preferred aspect of the invention.

 Independently of the fatty phase, a gelled aqueous phase is prepared containing a polyelectrolyte type polymer whose ion sites are associated with their counterions. Among the polymers of the polyelectrolyte type that may be used in the context of the present invention, mention may be made of: homopolymers based on a monomer having a strong acid function, partially or totally salified, homopolymers based on a monomer having a weak acid function, partially or totally salified, - homopolymers based on a cationic monomer, - copolymers based on at least one monomer having a strong acid function partially or totally salified, copolymerized: o with with minus a monomer having a weakly acid function partially or totally salified, o with at least one neutral monomer,

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 copolymers based on a cationic monomer copolymerized with at least one neutral monomer, copolymers based on at least one monomer having a weakly acid function partially or fully salified copolymerized: o with at least one monomer having a weak acid function partially or totally salified, o with at least one neutral monomer.

 In this context, the phrase "partially or totally salified" means that the strong acid or weak acid functions are partially or totally salified in particular in the form of an alkali metal salt, such as sodium salt or potassium salt, sodium salt. ammonium or aminoalcohol salt, such as, for example, the monoethanolamine salt.

 The strong acid function of the monomer can in particular be the sulphonic acid function or the phosphonic acid function, said functions being partially or totally salified.

 Said monomer will advantageously be chosen from styrene sulphonic acid or 2-sulphoethyl methacrylate, styrene phosphonic acid, partially or totally salified, 2-methyl-[(1-oxo-2-propenyl) amino] 1-Propane sulfonic acid (AMPS) partially or totally salified in the form of sodium salt, ammonium salt or monoethanolamine salt.

 The weak acid function of the monomer can in particular be the carboxylic acid function partially or totally salified. Said monomer may especially be chosen from acrylic acid, methacrylic acid, itaconic acid or maleic acid partially or totally salified in the form of sodium salt, potassium salt, ammonium salt or monoethanolamine salt.

 When the polymer is a copolymer based on a monomer having a strong acid functional partially or fully salified copolymerized with at least one neutral monomer, said neutral monomer is chosen in particular from acrylamide, methacrylamide, vinylpyrrolidone, (2-hydroxyethyl acrylate), (2,3-dihydroxypropyl) acrylate, (2-hydroxyethyl) methacrylate or (2,3-dihydroxypropyl) methacrylate or an ethoxylated derivative of molecular weight between 400 and 1000, each of these hydroxylated esters, tris (hydroxymethyl) -acrylamidomethane or tris (hydroxymethyl) methacrylamidomethane or an ethoxylated derivative of molecular weight between 400 and 1500, of each of these amides.

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 The fact that the aqueous phase of the emulsions according to the present invention comprises a polyelectrolyte whose ionic sites are associated with their counter ions contributes to the fact that the additional supply of mineral salts is not necessary.

 The polymers mentioned above can be "connected" or "crosslinked". "Connected polymer" denotes a nonlinear polymer which has pendant chains so as to obtain, when this polymer is dissolved in water, a high state of entanglement leading to very large low gradient viscosities. The term "crosslinked polymer" denotes a nonlinear polymer in the form of a three-dimensional network which is insoluble in water but swellable with water and thus leads to the production of a chemical gel.

 When the polymer is crosslinked and / or connected, the crosslinking agent and / or the branching agent is especially chosen from diethylenic and polyethylenic compounds, and especially from diallyloxyacetic acid or a salt thereof, and in particular its salt. sodium, triallylamine, trimethylol propanetriacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diallylurea or methylene bis (acrylamide).

 The crosslinking and / or branching agent is generally used in the molar proportion, expressed relative to the monomers used, of 0.005% to 1%, especially of 0.01% to 0.2% and more particularly of 0%, 01% to 0.1%.

 In general, the polyelectrolyte polymers which are suitable for producing emulsions according to the present invention are therefore copolymers or homopolymers, which may or may not be crosslinked or branched, comprising monomers having a strong or weak acidic function, partially or totally salified, or a cationic function.

 Among the polyelectrolyte polymers which are particularly suitable for carrying out the process of the present invention, mention may be made of the derivatives of acrylamide, acrylic acid and vinylpyrrolidone such as the copolymers of the acid. and 2-methyl-[(1-oxo-2-propenyl) amino] 1-propane sulfonic acid (AMPS), the copolymers of acrylamide and 2-methyl-1 (2-oxo-2-propenyl) amino] 1-propane sulfonic acid, copolymers of 2-methyl-[(1-oxo-2-propenyl) amino] 1-propane sulfonic acid and (2- hydroxyethyl), homopolymer of 2-methyl-[(1-oxo-2-propenyl) amino] 1-propane sulfonic acid, homopolymer of acrylic acid, copolymers of acryloyl ethyl trimethyl chloride ammonium and acrylamide, copolymers of AMPS and vinylpyrrolidone, copolymers of acrylic acid and alkyl acrylates whose carbon chain comprises between ten and thirty

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 carbon atoms, copolymers of AMPS and alkylacrylates whose carbon chain comprises between ten and thirty carbon atoms.

 Such polymers are generally prepared by a reverse phase polymerization process, and are marketed respectively under the names SIMULGEL EG, SEPIGEL 305, SIMULGEL NS, SIMULGEL 800 and SIMULGEL A by the company SEPPIC. They involve partially or fully salified forms of the acidic monomers. The corresponding monomer (s) is (are) dissolved in drops of water dispersed in a fatty phase with the aid of a surfactant. In this type of polymerization, each drop of water in the water-in-oil emulsion constitutes in itself a "small reactor". This system minimizes the probabilities of termination reactions and leads to higher molecular weight polymer chains. At the end of the reaction, a hydrophilic surfactant and water are added. The polymer unfolds, being no longer constrained by the size of the drop of water in which it was synthesized, leading to a "soft solid", characterized by a three-dimensional structure.

 This preparation process uses surfactants, such as sorbitan esters, mannitan esters, polyhydroxystearates of polyglycols, polyglycerols or polyols, alkanolamides on linear or branched fatty chains, ethoxylated sorbitan esters, esters and the like. ethoxylated mannitan, ethoxylated nonylphenols, ethoxylated octylphenols. As a result, the surfactants mentioned above may be present in the gelled aqueous phase during the implementation of the process of the invention.

 Advantageously, the dry weight of said polyelectrolyte constitutes between 0.1% and 4% and preferably between 0.5% and 2% by weight of the aqueous phase, if the process for preparing such a polyelectrolyte results from a polymerization process. precipitating; or the dry weight of said polyelectrolyte is between 0.25% and 4% and preferably between 0.5% and 2% of the weight of the aqueous phase if the process for preparing such a polyelectrolyte results from a process for the preparation of inverse emulsion polymerization.

 The polyelectrolyte polymers used in the process of the present invention have a shear-thinning (non-Newtonian) behavior, i.e., the observed viscosity varies with the shear rate.

 Without wishing to be bound by any particular theory, it is believed that this rheofluidifying (non-Newtonian) behavior is likely to be related to the three-dimensional structure of the polyelectrolyte polymers, which also influences the physical properties of the emulsions. There is therefore a correlation

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 between the behavior of polymers in viscosity and their ability to facilitate the formation of emulsions.

 Advantageously, the polyelectrolyte type polymers that can be used in the context of the present invention exhibit a non-Newtonian rheological behavior in solution, characterized by a gradient index of between 0.1 and 0.7, and preferably between 0.2 and 0.5.

 Advantageously, the gelled aqueous phase obtained by dissolving the polyelectrolyte-type polymer will have a viscosity of between 0.5 and 300 Pa.s, preferably between 1.0 and 150 Pa.s and more particularly between 5 and 100 Pa.s. , measured on a BROOKFIELD LV viscometer (6 rpm, 20 C).

 The water-in-oil emulsion according to the present invention may also optionally contain up to 10% by weight of a stabilizer.

 Among the stabilizing agents that may be used in the context of the present invention, mention may be made of hydrogenated castor oil; stearic acid and its metal salts such as aluminum stearate; hydrophobic silicas; polymers such as the products marketed under the name KRATON POLYMERS by KRATON; clays such as hectorite or bentonite; hydrophobic modified starches, for example the product sold under the name DRY FLO PC # by the company National Starch; polymethylmethacrylates crosslinked or not, such as MICROPEARL sold by the company SEPPIC, polyamides such as Orgasol 2002 marketed by the company ATOCHEM.

 Waxes of vegetable, animal or mineral origin, such as beeswax, carnauba wax or ozokerite, are also likely to be used in the context of the present invention, even if for practical reasons, they do not represent a preferred aspect of the invention.

 In a manner known per se, these emulsions may furthermore comprise one or more compounds chosen from humectants, for example glycerin, preservatives, for example the products known under the name SEPICIDE® and marketed by the company SEPPIC. dyes, perfumes, cosmetic active agents, mineral or organic sunscreens, mineral fillers such as iron oxides, titanium oxides and talc, synthetic fillers such as nylons and crosslinked or uncrosslinked poly (methyl methacrylate) silicone elastomers, sericite and plant extracts.

 The water-in-oil emulsion may also comprise one or more electrolytic mineral salts, for example magnesium chloride or sulphate.

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 magnesium, sodium borate or sodium chloride in an amount of from 0.1% to 5% by weight. These electrolytes are however not essential for obtaining the emulsions according to the invention.

 These compounds may be introduced into the aqueous phase or into the oily phase, depending on their affinity for these phases.

 The emulsions according to the invention are obtained by adding the fatty phase to the aqueous phase. It is possible to operate at temperatures up to 80 C. However, it is advantageous to minimize the energy expenditure that represents the heating of the phases and it will therefore be preferred to make the emulsion at a temperature below 55 C. more preferably, the fatty phase is added to the gelled aqueous phase at a temperature of between 20 ° C. and 35 ° C., that is to say at room temperature.

 The emulsion according to the invention can be made by mixing the two phases at a stirring speed exceeding 1500 rpm. It is advantageous, however, to minimize the energy expended in the agitation used to make the emulsion. Therefore, a stirring speed of less than 1000 rpm is preferred, and a stirring speed of between 80 and 800 rpm is particularly preferred. Even more preferentially, a stirring speed of between 80 and 450 rpm, especially between 80 and 330 rpm, will be chosen.

 The emulsions according to the invention, which are stable over time, advantageously have a polydispersity index greater than 41%, preferably greater than 45% and more preferably greater than or equal to 51%.

 In this context, the polydispersity is determined by particle size analysis on a diluted form of the emulsion using a MALVERN MASTERSIZER type laser granulometer.

 In particular, by implementing the operating conditions of the process of the present invention, it is possible: to combine the fatty and aqueous phases, which are both at room temperature, to perform this combination of phases without constraint as to the rate of introduction of one phase into the other, - to achieve the emulsion with gentle relative stirring by means of stirring systems of simple geometry (anchor, marine propeller, Rayneri type deflocculator),

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 to avoid the use of additional substances which are often indispensable for the preparation of high water content W / O emulsions of the prior art, such as in particular microcrystalline waxes and electrolyte mineral salts.

 In addition, in the process according to the invention the order of addition of the phases is reversed with respect to the usual order of preparation of a water-in-oil emulsion (W / O). Adding the fatty phase to the aqueous phase represents a productivity gain in itself. Indeed, the fatty phase is of a smaller volume than the aqueous phase, which can allow the use of a single preparation tank, and has a much lower viscosity.

 The W / O emulsion according to the invention can be advantageously used in a cosmetic, dermocosmetic, pharmaceutical or veterinary preparation. The W / O emulsion according to the invention can also be used in a detergent preparation.

 The invention will be illustrated by the following examples.

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EXAMPLES EXAMPLE 1 Preparation of a W / O Emulsion Two phases are prepared separately, having the following compositions: Fat phase

<Tb>
<tb> Alkyl <SEP> polyxylosides <SEP> on <SEP> Isofol <SEP> 20
<tb> prepared <SEP> according to <SEP> EP1142901 <SEP> 1.6 <SEP>% <SEP>
<tb> PEG45 <SEP> dodecylglycol <SEP> copolymer <SEP> (ELFACOS <SEP> ST9) <SEP> 0.4 <SEP>% <SEP>
<tb> Triglyceride <SEP> C8-C10 <SEP> 8.0 <SEP>% <SEP>
<tb> Phase <SEP> aqueous
<tb> Water <SEP> qs <SEP> 100%
<tb> Glycerin <SEP> 5%
<tb> SIMULGEL <SEP> EG <SEP> 2%
<Tb>

The fatty phase is heated moderately (up to 50 ° C.) until the mixture of the three constituents is clear. This fatty phase can be stored at room temperature for several days without causing crystallization of the various surfactants present.

 The aqueous gel comprising water, a water-soluble polymer presented as an inverse emulsion under the trade name Simulgel EG, and glycerin is prepared at room temperature with conventional stirring for this type of preparation (RAYNERI deflocculator), at a temperature of 18 ° C. 25 C, with a stirring speed of 300 rpm.

 The fatty phase is added all at once to the gel, at ambient temperature and at a moderate stirring speed (200 to 300 rpm) with an agitator equipped with an anchor type mobile. This stirring is then maintained for ten minutes and no cooling step is necessary.

 Moreover, the emulsion obtained is a water-in-oil emulsion which, due to its high water content, has a strong rheofluidifying character associated with a non-tacky and fresh feel.

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EXAMPLE 2 Preparation of a W / O Emulsion
The same procedure as that described in Example 1 is used in an 8 kg pilot reactor equipped with a planetary mixer. The emulsification rate with such a system was 100 rpm and the maintenance phase, after the end of the addition of the fat phase, lasted thirty minutes.

EXAMPLE 3 Influence of the energy provided by the quality of the agitation
The conditions of Example 1 were reproduced using a stator rotor stirrer, operating at a speed of 4000 rpm, to achieve the emulsion.

EXAMPLE 4 Combined Influences of the Quality of Agitation and the Emulsification Temperature
The fatty phase is heated to 80 C until the mixture of the three constituents is clear.

 The aqueous gel comprising water, a water-soluble polymer presented in inverse emulsion under the trade name Simulgel EG, and glycerine is prepared at room temperature with conventional stirring for this type of preparation (RAYNERI deflocculator). It is then heated to 80 C.

 The fatty phase is added all at once to the gel, and the stirring conditions of Example 3 are reproduced.

 The emulsion is then cooled with moderate stirring with an anchor for 20 minutes.

The properties of the emulsions obtained according to Examples 1 to 4 are collated in Table 1.

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Table 1

<Tb>
<tb> Exem <SEP><SEP> 1 <SEP> Example <SEP> 2 <SEP> Example <SEP> 3 <SEP> Exempt <SEP> 4
<tb> Quantity <SEP> manufactured <SEP> 200g <SEP> 8kg <SEP> 200 <SEP> 200
<tb> Temperature <SEP> 20-25 C <SEP> 20-25 C <SEP> 20-25 C <SEP> 80 C
<tb> emulsification
<tb> Stirring speed <SEP><SEP> 300 <SEP> rpm <SEP> 100 <SEP> rpm <SEP> 4 <SEP> 000 <SEP> rpm <SEP> 4 <SEP > 000 <SEP> rpm
<tb> when <SEP> of <SEP>
<tb> emulsification
<tb> Characteristics <SEP> of <SEP> W / W <SEP> W / W <SEP> W / W <SEP> W / W
<tb> the <SEP> emulsion obtained /
<tb> SENS <SEP> (1)
<tb> VISCOSITY <SEP> (2) <SEP> 55.6 <SEP> Pa. <SEP> s <SEP> 58.0 <SEP> Pa. <SEP> s <SEP> 51.2 <SE> Pa <SEP> s <SEP> 51.2 <SEP> Pa. <SEP> s
<Tb>
(1) method: 1g of emulsion is diluted in 5g of demineralized water. If the emulsion is immiscible with water, it is E / H.

(2) method: BROOKFIELD LV 6rpm (at 20 C)
The comparison of Examples 3 and 4 with Example 1 shows that the direction of the W / O emulsion and the order of magnitude of the viscosity of the emulsion obtained are similar regardless of the amount of energy supplied to the system. .

 On the other hand, the comparison of Examples 1 and 2 shows that the extrapolation of the process on a pilot scale results in similar performances, without any significant modification of the operating conditions relating to the emulsification phase.

EXAMPLE 5: The rheological behavior of an aqueous gel that can be used in the context of the present invention
The rheological behavior of different gelled aqueous phases, containing a polyelectrolyte type polymer, was studied in the absence of an organic phase using an imposed stress rheometer CSL500, sold by the company TA Instruments. The viscosity measurements are carried out at 20 ° C. The gradient indices, indicated in Table 2, are obtained by calculating the convexity of the curve analyzed according to the mathematical model of the power law.

<Desc / Clms Page number 19>

Table 2

<Tb>
<tb> POLYELECTROLYTE <SEP> QUANTITY <SEP> EN <SEP> Index <SEP> of <SEP> Viscosity
<tb> STUDY <SEP> WEIGHT <SEP> SEC <SEP> IN <SEP> gradient <SEP> Brookfield
<tb> THE <SEP> PHASE <SEP> LV <SEP> 6 <SEP> RPM <SEP>
<tb> AQUEOUS <SEP> (Pa.s)
<tb> (%)
<tb> Copolymer <SEP> of <SEP> 0.96 <SEP> 0.28 <SEP> 70
<tb> AMPS <SEP> and <SEP> of <SEP> Acid
<tb> acrylic
<tb> Copolymer <SEP> of <SEP> 0.8 <SEP> 0.32 <SEP> 60
<tb> the AMPS <SEP> and <SEP> of <SEP>
<tb> acrylamide
<tb> Copolymer <SEP> of <SEP> 1.06 <SEP> 0.31 <SEP> 73
<tb> the AMPS <SEP> and <SEP> of <SEP>
<tb> Hydroxyethyl
<tb> Acrylate
<tb> Homopolymer <SEP> of <SEP> 0.95 <SEP> 0.34 <SEP> 61
<tb> the AM <SEP> PS <SEP>
<tb> Copolymer <SEP> of <SEP> 0.9 <SEP> 0.34 <SEP> 70
<tb> the AMPS <SEP> and <SEP> of <SEP> the <SEP> vinyl
<tb> pyrolidone
<tb> Copolymer <SEP> of <SEP> 0.7 <SEP> 0.4 <SEP> 69
<tb> acid <SEP> acrylic <SEP> and
<tb> of <SEP> C10-30
<tb> alkylacrylates
<tb> Homopolymer <SEP> of <SEP> 1.5 <SEP> 0.48 <SEP> 61
<tb> acid <SEP> acrylic
<Tb>

These results show that the aqueous gels, obtained from polyelectrolyte type polymers, have a rheofluidifying character. This profile is illustrated by the measurement of the gradient index
It is observed that the gradient index is generally less than 0.5 for gels based on polyelectrolyte polymers. Other studies, the results of which are not indicated, show that aqueous gels obtained from

<Desc / Clms Page number 20>

 polyethylene glycols, have a gradient index close to 1, thus reflecting a quasi-Newtonian character.

EXAMPLE 6 Polydispersity of an Emulsion According to the Present Invention Two phases are prepared separately having the following compositions: Fat phase

<Tb>
<tb>#<SEP> FLUIDANOV <SEP> 20X1 <SEP> 0,50%
<tb> (octyldodecanol <SEP> polyxyloside <SEP> and <SEP> octyldodecanol)
<tb>#<SEP> ARLACEL <SEP> P <SEP> 135 <SEP> 0.10%
<tb> (polyhydroxystearate <SEP> from <SEP> PEG <SEP> 1500)
<tb>#<SEP> LANOL <SEP> 99 <SEP> 4.40%
<tb> (isononyl isononanoate <SEP>)
<Tb>
Aqueous phase

<Tb>
<tb>#<SEP> SIMULGEL <SEP> EG <SEP> 2.85%
<tb> (sodium <SEP> acrylate <SEP> / <SEP> sodium <SEP> acryloyl <SEP> dimethyl <SEP> taurate /
<tb> isohexadecane / <SEP> Polysorbate <SEP> 80)
<tb>#<SEP> Water <SEP> 92.15%
<Tb>
Prepared according to EP-A-1142901
These two phases were combined following the procedure of Example 1 above.

 The polydispersity of the water-in-oil emulsion obtained was measured according to the method indicated above (particle size analysis on a diluted form of the emulsion using a MALVERN MASTERSIZER type laser granulometer).

 The polydispersity index of the emulsion was greater than 51%. On the other hand, the gradient index of the aqueous phase of this water-in-oil emulsion was 0.28.

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EXAMPLE 7 Influence of the viscosity of the aqueous gel on the direction of the emulsion Two phases having the following compositions are prepared separately: Fat phase

<Tb>
<tb> Alkyl <SEP> polyxylosides <SEP> on <SEP> Isofol <SEP> 20
<tb> prepared <SEP> according to <SEP> EP1142901 <SEP> 2.4%
<tb> PEG45 <SEP> dodecylglycol <SEP> copolymer <SEP> (ELFACOS <SEP> ST9) <SEP> 0.6%
<tb> Triglyceride <SEP> C8-C10 <SEP> 12.0 <SEP>% <SEP>
<tb> Phase <SEP> aqueous
<tb> Water <SEP> qs <SEP> 100%
<tb> SIMULGEL <SEP> EG <SEP> x%
<Tb>

The conditions of Example 1 were reproduced using an anchor type agitator operating at a speed of 300 rpm to effect the emulsion.

 The viscosity of the aqueous phase and the resulting direction of the emulsion, prepared according to the procedure described above, are reported in Table 3.

Table 3

<Tb>
<tb> Quantity <SEP> of <SEP> Quantity <SEP> of <SEP> Viscosity <SEP> of <SEP><SEP> Characteristic <SEP> of
<tb> SIMULGEL <SEP> EG <SEP> polyelectrolyte <SEP> phase <SEP> aqueous <SEP> Emulsion / Sens <SEP> (2)
<tb> Used <SEP> (1) <SEP> Used <SEP> (1) <SEP> Pa. <SEP> s
<tb> 2 <SEP> 55 <SEP>% <SEP> 1.0 <SEP>% <SEP>><SEP> 100 <SEP> W / H
<tb> 1 <SEP> 70 <SEP>% <SEP> 0.67 <SEP>% <SEP> 65 <SEP> W / H
<tb> 1.27 <SEP>% <SEP> 0.50 <SEP>% <SEP> 40 <SEP> W / H
<tb> 0.85 <SEP>% <SEP> 0.33 <SEP>% <SEP> 2.0 <SEP> W / H
<tb> 0.61 <SEP>% <SEP> 0.24 <SEP>% <SEP> 0.4 <SEP> H / E
<Tb>
(1) quantity expressed in weight% relative to the total mass of the emulsion (2) method: 1 g of emulsion is diluted in 5 g of demineralized water. If the emulsion is immiscible with water, it is E / H.

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 These results show that an aqueous phase whose viscosity is less than 0.5 Pa.s does not make it possible to produce a water-in-oil emulsion under the conditions of the invention.

Claims (11)

 1. Emulsion consisting of an outer fatty phase and a gelled aqueous phase, said aqueous phase representing 60 to 98% by weight of the composition, characterized in that: - the aqueous phase comprises a polyelectrolyte type polymer; and the fatty phase comprises one or more oils and an emulsifying system of lipophilic nature, comprising one or more emulsifying surfactants. 2. A process for preparing a water-in-oil type emulsion, as defined in claim 1, comprising the following steps: a) preparing a fatty phase comprising one or more oils, and an emulsifying system of lipophilic nature, comprising one or more emulsifying surfactants; b) a gelled aqueous phase containing a polyelectrolyte-type polymer is prepared independently of the fatty phase; c) the fatty phase is added to the aqueous phase. 3. Process according to claim 2, in which the emulsifying system comprises at least one emulsifying surfactant chosen from alkylpolyglycosides, alkylpolyglycoside and fatty alcohol compositions, esters of polyglycerols or of polyglycols or of polyols such as polyhydroxystearates of polyglycols. or polyglycerol. 4. A process according to any of claims 2 and 3 wherein the emulsifier system comprises a polyol polyhydroxystearate or a polyglycerol ester, in combination with an alkylpolyglycoside and fatty alcohol composition. 5. Method according to one of claims 2 to 4 wherein said polyelectrolyte type polymer is selected from the group consisting of copolymers or homopolymers, which may or may not be crosslinked or connected, based on monomers having a strong acid function or a partially or totally salified weak acid, or a cationic function, said monomers being preferably chosen from styrene sulphonic acid or 2-sulphoethyl methacrylate, partially or completely salified styrene phosphonic acid, [(1-Oxo-2-propenyl) amino] 1-propane sulfonic acid (AMPS) partially or totally salified in the form of sodium salt, ammonium salt or monoethanolamine salt. <Desc / Clms Page number 24> 6. Process according to any one of Claims 2 to 6, in which the polyelectrolyte-type polymer is chosen from copolymers of acrylic acid and 2-methyl-[(1-oxo-2-propenyl) acid). amino] 1-propanesulfonic acid (AMPS), copolymers of acrylamide and 2-methyl-[(1-oxo-2-propenyl) amino] 1-propane sulfonic acid, copolymers of 2-methyl-[(1-oxo-2-propenyl) amino] 1-propanesulfonic acid and (2-hydroxyethyl) acrylate, the homopolymer of 2-methyl-[(1-oxo) 2-propenyl) amino] 1-propane sulfonic acid, homopolymer of acrylic acid, copolymers of acryloyl ethyl trimethyl ammonium chloride and acrylamide, copolymers of AMPS and vinylpyrrolidone, copolymers of acrylic acid and alkyl acrylates whose carbon chain comprises between ten and thirty carbon atoms, copolymers of AMPS and alkyl acrylates whose carbon chain comprises between ten and thirty carbon atoms 7. Method according to any one of claims 2 to 6 wherein the aqueous phase comprises at least one emulsifying surfactant. 8. Method according to one of claims 2 to 7 wherein the gelled aqueous phase is obtained by dissolving said polyelectrolyte type polymer and has a viscosity of between 0.5 and 300 Pa.s, preferably between 1.0 and 150 Pa. S and more particularly between 5 and 100 Pa.s. 9. Method according to any one of claims 2 to 7 wherein the fatty phase is added to the aqueous phase at a temperature below 55 C and preferably between 15 and 35 C. 10. Process according to any one of claims 2 to 9 wherein the two phases are mixed with a stirring speed of less than 1000 rpm and preferably between 80 and 800 rpm. Cosmetic, pharmaceutical, veterinary or detergent preparation comprising an emulsion according to claim 1 or an emulsion prepared by the process according to any one of claims 2 to 10.