EP3727321A1

EP3727321A1 - Emulsifying composition and method for producing an o/w pickering emulsion composition

Info

Publication number: EP3727321A1
Application number: EP18845299.9A
Authority: EP
Inventors: Léon Mentink; Daniel Wils; Anne-Marie Lheritier; Marc LAVARDE; Sophie PIOT
Original assignee: Roquette Freres SA
Current assignee: Roquette Freres SA
Priority date: 2017-12-21
Filing date: 2018-12-19
Publication date: 2020-10-28
Also published as: CN111491614A; FR3075604A1; JP2021507915A; KR20200101921A; WO2019122704A1; FR3075604B1; JP7434156B2

Abstract

An emulsifying composition, in particular for cosmetic use, that is capable of obtaining an oil-in-water (O/E) emulsion, comprising: a. at least one cyclodextrin, b. and at least one O/E emulsifier of natural origin, the O/E emulsifier having a hydrophilic-lipophilic balance (HLB) of less than 8. A method for producing an O/W Pickering emulsion composition, in particular for cosmetic use, comprising the following steps: a) dispersing, in an aqueous phase, an emulsifying composition comprising at least one cyclodextrin and at least one O/E emulsifier of natural origin, the latter being present in a ratio of between 0.01 and 1 part, and preferably between 0.15 and 0.30 parts to 1 part by weight of at least this cyclodextrin; this O/E emulsifier of natural origin being chosen from at least one non-ethoxylated fatty ester of polyols having a hydrophilic-lipophillic balance (HLB) of less than 8, b) adding, to the mixture obtained in step a), a fatty phase, in an amount of between 10 and 65% by weight, with sufficient mechanical stirring for the fatty phase to disperse into fine droplets in the aqueous phase and for an O/W emulsion having a drop size smaller than 10 μm to be obtained.

Description

Emulsifying composition and process for producing a Pickering O / W emulsion composition

The present invention relates to an emulsifying composition of plant origin ready for use and directly usable cold which finds applications particularly in the field of cosmetics. This composition is self-sufficient and directly stabilizes an emulsion without the necessary addition of a co-emulsifier. This emulsifying composition makes it possible in particular to easily produce very fine O / W emulsions with various textures, which are very compatible with the skin and furthermore have a dry, fresh, silky and non-greasy feel, even with a high fat content. in the emulsion.

An emulsion is a dispersion of a liquid (or a material made liquid) in fine droplets in another liquid immiscible with the first. It has a macroscopically homogeneous appearance but appears heterogeneous under the microscope. The liquid in the form of droplets is called dispersed phase (or discontinuous), while the other liquid is called dispersant phase (or continuous). In general, an emulsion is composed of water and oil and two phases (single emulsion): a hydrophilic phase (aqueous) and a lipophilic phase (fat). The emulsions most commonly encountered are emulsions comprising a lipophilic phase dispersed in a continuous aqueous phase and are called oil-in-water (O / W) emulsions, as opposed to water-in-oil (W / O) emulsions.

Many cosmetic compositions are emulsions, typically simple emulsions, stabilized by surfactants. By way of example, EP 0 685 227 proposes a very complex system of antisolar cosmetic compositions, comprising an aqueous continuous phase, a protective system capable of filtering UV rays, a surfactant, and organic solvents (alcohols and lower polyols). and at least one polymer or more particularly a crosslinked copolymer (alkyl acrylates, vinyl acetate).

Document FR 2 858 777 describes an oil-in-water emulsion containing at least one fatty substance (esters of fatty acids, waxes, butters, natural oils - vegetable, animal, of marine origin), synthetic or mineral, hydrogenated oils and mixtures thereof), at least one surfactant (ethoxylated polyglycerol fatty acid esters, alcohol ethoxylates), at least one co-surfactant and water.

However, the use of surfactants in products intended to be applied in humans or animals, whether in topical, oral or other forms, can be problematic. Indeed, surfactants can damage cell membranes. Thus, efforts are made, particularly in the cosmetic field, to reduce the potentially harmful effects of surfactants or eliminate the use of surfactants.

Also, an object of the present invention is to provide a composition which, in the presence of water, is capable of forming, even in a cold process, a stable emulsion by adding oil or fat. It eliminates the use of conventional surfactants, of petroleum origin and non-biodegradable, including no longer use derivatives of glycols and ethoxylated derivatives. From this point of view, the composition according to the present invention also makes it possible to manufacture Pickering type emulsions. Emulsions of this type are devoid of surfactant and are stabilized by colloidal particles such as usually silicas which are placed at the interfaces of the continuous phase and the dispersed phase. In the context of the present invention, these colloidal particles are organic particles consisting of inclusion complexes between at least one cyclodextrin and at least one fatty molecule. These particles are very advantageously compatible with the skin or the hair and do not damage the cellular membranes of animal nature.

This result is all the more remarkable as the state of the art demonstrates that the manufacture of emulsifying systems for cosmetic use and containing cyclodextrins, does not make it possible to obtain emulsions easily and directly cold: it was necessary until then to use conventional surfactants. This is particularly the document EP 2 091 502 B1 which describes an O / W emulsion containing water, a fatty substance, a modified polysaccharide, and a cyclodextrin, the essential characteristic of this O / W emulsion being that it contains surfactants with a molecular weight of less than 5,000 g / mol and less than 2% by weight. It was therefore not known, or obvious, to produce emulsifying systems containing cyclodextrins to obtain very fine and very stable emulsions and without resorting to ordinary surfactants.

Another object of the present invention is to provide a composition of 100% natural origin. The natural origin of ingredients used to formulate everyday products such as cosmetic compositions is today a major challenge, not only vis-à-vis the safeguarding and protection of our environment but also for the well being consumers. In this respect, the composition according to the present invention makes it possible to replace the traditional emulsifiers, in particular ethoxylated emulsifiers, which today are sought to be substituted for environmental issues (poor biodegradability) and safety (ethylene oxide is toxic and flammable). Another object of the present invention is to provide a ready-to-use composition, allowing the formulator a very simple implementation, with a minimum energy input, especially by introducing all the ingredients into the same tank or reactor (formulation called "one pot" in Anglo-Saxon language). From the point of view of its implementation, the composition which is the subject of the present invention is advantageously usable according to a "cold process", that is to say even at ambient temperature, unlike many solid or conventional solid emulsifiers. pastes such as waxes that require a rise in temperature for their implementation (ingredient requiring to be melted and usable "hot"). By "cold process" it is meant that the emulsifying composition can be carried out directly by dispersion in water at a water temperature below 45 ° C, better below 35 ° C and more preferably at room temperature.

Another object of the present invention is to provide a composition for cosmetic use broad spectrum, that is to say, versatile from the point of view of the end products envisaged: from this point of view, the composition according to the invention can be used in products as diverse as lotions, creams, gels, milks .... In addition, said composition is advantageously non-irritating and non-allergic to the skin. It also offers the advantage of not depending on the pH or the presence of electrolytes: in other words, its emulsifying capacity is not affected by the pH of the medium, or by the presence of mono salts, di or trivalent. This criterion is all the more important since, in general, products for cosmetic use and in particular for topical application are liable to be subjected to or exposed to variations in pH (for example, the pH of the skin is slightly acid, and varies between 4 and 6). Having a product that does not present a particular limit of use in terms of pH therefore represents a very great technical advantage for a cosmetic composition.

Finally, another object of the present invention is to provide a composition for cosmetic use, offering a wide range of sensory properties of interest, such as in particular a feeling of freshness in the epidermis or a creamy texture. Indeed, the emulsifying composition according to the invention allows easy realization of O / W emulsions that are both very stable and very fine, with modulable textures and having a fresh, silky and non-greasy feel, even for high levels of dispersed fatty phase. It is thus possible to obtain emulsions having a good emollient effect on the skin as well as a good moisturizing effect of the upper layers of the epidermis.

All of these objectives, which constitutes a complex technical problem to be solved, are finally achieved thanks to the main object of the present invention, which consists of a emulsifying composition, in particular for cosmetic use, suitable for obtaining an oil-in-water emulsion (O / W), comprising:

1) at least one cyclodextrin,

2) and at least one W / O emulsifier of natural origin. the W / O emulsifier having a hydrophilic-lipophilic balance (HLB) of less than 8.

The calculation of the HLB takes into account the molecular masses of the hydrophilic parts and the molecular mass of the molecule considered and can be obtained according to the following equation:

Mass excee be part of mirroring

HLB 2

Mass ole this way of the molecule

In the present Application, the term "cyclodextrin" refers to and includes any of otherwise known cyclodextrins, such as native and unsubstituted cyclodextrins containing from 6 to 12 glucose units linked by covalent bonds between carbons 1 and 4 , and in particular alpha-, beta- and gamma-cyclodextrins containing respectively 6, 7 and 8 units of glucose.

This term also covers "cyclodextrin derivatives", ie molecules of which at least part of the hydroxyl groups OH has been converted into groups OR, where R generally denotes an alkyl group. From this point of view, the cyclodextrin derivatives include, in particular, methylated and ethylated cyclodextrins, but also those substituted with a hydroxyalkyl group such as hydroxypropylated and hydroxyethylated cyclodextrins.

Preferred cyclodextrins according to the present invention are alpha-, beta- and gamma-cyclodextrins, with native beta-cyclodextrin being most preferred.

The cyclodextrin may especially be in the form of a crystalline powder, pseudocrystalline or amorphous.

In the present Application, the term "emulsifier W / H of natural origin" denotes any molecule derived from renewable resources, in particular extracted or secreted by plants, microorganisms or algae and able to allow after physical modification, chemical or enzymatic, obtaining a water-in-oil emulsion W / O or to promote stability. Under this definition, therefore, are included products called co-emulsifiers E / H.

The Applicant has been able to note after many tests and experimental plans, that quite surprisingly and unexpectedly, the combination with a cyclodextrin, an emulsifier used for the preparation of W / O type emulsions having a balance Hydrophile-Lipophilic (HLB) less than 8, far from preventing the formation of an emulsion in the opposite direction, ie of O / W type, and compromising the stability of this type of O / W emulsion , has a very favorable effect on the preparation thereof and acts as a stabilizer, making the emulsion more stable in time and temperature.

This is all the more surprising since the effectiveness of an emulsifier is known to be primarily related to its solubility in each of the two phases. The phase in which the emulsifier is the most soluble forms the continuous phase of the emulsion. Thus, a water-soluble emulsifier stabilizes an oil-in-water O / W emulsion. However, the emulsifying composition according to the present invention, which can be used directly in the cold state to prepare O / W emulsions, has a particularly low solubility in water, of the order of only 1.8% at 25 ° C. when it is retained. according to the preferred mode, as cyclodexrin, beta-cyclodextrin.

Without wishing to be bound by any theory, it appears that the presence of very small amounts of a naturally occurring W / O emulsifier greatly facilitates the in situ formation of inclusion complexes between cyclodextrin and certain specific molecules present in the body. the dispersed fatty phase, and this in the form of colloidal particles, solid or semi-liquid, which are placed at the oil and water interfaces. These particles are very physically and sensorially compatible with the skin or hair and do not damage the cell membranes of animal nature

It has been shown that for a given amount of cyclodextrin, the addition in small amounts of a naturally occurring W / O emulsifier, allows a reduction of the drop size within the O / W emulsion and the to obtain more spherical droplets. It has also been shown that this addition makes it possible to adjust the final viscosity of the O / W emulsion.

The W / O emulsifier of natural origin having a hydrophilic-lipophilic balance (HLB) of less than 8 is preferably present in the emulsifying composition in a ratio of between 0.01 and 1 part, preferably between 0.05 and 0.5 parts, more preferably between 0.10 and 0.35 parts and more preferably between 0.15 and 0.30 for 1 part by weight of cyclodextrin. By way of example, this emulsifier of natural W / O origin may be chosen from the following products, provided that they satisfy the condition on the HLB above: the non-ethoxylated fatty esters of polyols, and in particular from non-ethoxylated fatty esters of glycerol, polyglycerols, sorbitol, sorbitan, anydrodrohexitols such as in particular isosorbide, mannitol, xylitol, erythritol, maltitol, sucrose, glucose, polydextrose, hydrogenated glucose syrups, dextrins and hydrolysed starches.

The W / O emulsifier of natural origin is preferably chosen to be naturally biodegradable in a natural hydrated medium. It can be in particular non-ethoxylated fatty esters of polyols obtained from fatty acid or by trans-esterification from oil or oil mixtures. The fatty acids used comprise from 8 to 22 carbon atoms, preferably from 10 to 18 carbon atoms, and in particular from 12 to 18 carbon atoms. These acids can be linear or branched, saturated or unsaturated, possess one or more side hydroxyl functions. The oils may be saturated or unsaturated, from liquid to solid at room temperature, and optionally have hydroxyl functional groups, preferably having an iodine number between 1 and 145, and in particular from 5 to 105.

The W / O emulsifier of natural origin can also be chosen from products that are naturally biodegradable in a hydrated natural medium, with in particular a hydrophilic-lipophilic balance (HLB) of between 1.5 and 6, preferably between 2 and 5 and better still between 3 and 5.

The W / O emulsifier of natural origin may in particular be chosen from fatty esters of glycerol, and in particular from oleates, stearates, glycerol isostearates, for example the following products: glyceryl laurate HLB 5.2, glyceryl oleate HLB 4 such as IMWITOR 948, Lubrizol Schercemol's Schercemol GMIS HLB 3.5 glyceryl isostearate and Sympatens-GMS glyceryl monostearate HLB 3.5.

It can also be chosen from fatty esters of sorbitan or sorbitol, in particular from laurates, palmitate, oleates, stearate, sorbitan isostearates, for example the sorbitan trioleate Kosteran-O / 3 HLB 1.8; sorbitan oleate MONTANE 80 VG or SPAN 80-LQ- (RB) or Kosteran-O / 1 HLB 4.3; sorbitan isostearate Kosteran-1/1 HLB 4.3, sorbitan stearate Kosteran-S / 1 HLB 4.7; sorbitan monopalmitate HLB 6.6; sorbitan laurate Kosteran L / l HLB 8.6,. It may also be chosen from sucrose fatty esters, for example Sisterna SP60-C sucrose distearate, Sisterna SP10-C sucrose polystearate, and HLB 6 sucrose cocoate.

The W / O emulsifier of natural origin may in particular be chosen from the polyglycerol esters and preferably from the esters resulting from the reaction of polyglycerols comprising from 2 to 12 glycerol units, preferably from 3 to 6 glycerol units with at least one partially hydrogenated or non-hydrogenated vegetable oil having an iodine number of between 1 and 15, and in particular of 5 to 10. It may be in particular oleic, stearic, isostearic and ricinoleic esters of polyglycerols and particularly the following products: polyglyceryl-4 isostearate HLB 3 (as HYDRIOL ^® ERP HYDRIOR), polyglyceryl-10 pentaoleate HLB 3.5 (as Decaglyn 5-OV), polyglyceryl-6 polyricinoleate (as HEXAGLYN PR-15), polyglyceryl-2 sesquiisostearate HLB ~ 4 (as Hostcerin IMB Clariant and Dermofeel ^® GO soft Evonik Dr. Straetmans), polyglyceryl-3 ricinoleate HLB 3.5, polyglyceryl-3 polyricinoleate HLB 4 (as Imwitor 600), polyglyceryl -3 polyricinoleate HLB: ~ 4 (as Dermofeel ^® PGPR Evonik Dr. Straetmans GmbH), polyglyceryl-2 sesquioleate HLB 4 (as Dermofeel ^® GO soft Evonik Dr. Straetmans GmbH), polyglyceryl-2 diisostearate (as Emulpharma ^® PG20 of Res Pharma), polyglyceryl-3 diisostearate HLB: 5.5 (such as Plurol ^® Diisostearique CG from Gattefossé, Lameform ^® TGI from BASF, IMWITOR ^® PG3 DIS from IOI Oleo GmbH, Cithrol ™ PG32IS from Croda, DUB ISO G3 from Stéarinerie Dubois, ^® Polyaldo 3-1-S Lonza, 7245 Jolee of OIéon and MASSOCARE PG3D Masso), polyglyceryl-3 oleate HLB 6.2 (such as MUL PGO-31 Ivanhoe Industries), polyglyceryl-3 LB 7.2 monostearate, polyglyceryl-4 oleate HLB 8 (as HYDRIOL ^® PGM0.4 of HYDRIOR), polyglyceryl-5 dioleate HLB 8 (as Dermofeel ^® G 5 OD Dr. Straetmans Evonik GmbH), polyglyceryl-2 dipolyhydroxystearate (Dehymuls PGPH as Cognis), polyglyceryl-2 diisostearate (as Emulpharma PG20 from Respharma), polyglyceryl-3 cocoate (as Emulpharma ^® Eco Res Pharma tech).

The preferred ester is that resulting from the reaction of polyglycerol-3 and isostearic acid (INCI name: polyglyceryl-3 diisostearate).

The W / O emulsifier of natural origin may consist of mixtures of fatty esters, in particular of polyglycerol fatty esters, of sorbitan fatty esters or of glucose esters, such as in particular mixtures such as the Nikkomulse WO products. -NS from Nikko Chemicals (Polyglyceryl-6 polyricinoleate, polyglyceryl-2 isostearate, disteardimonium hectorite), Tego Care LTP from Evonik (sorbitan laurate, polyglyceryl-4 laurate, dilauryl citrate), Sympatens-W / 4500 (sorbitan oleate, polyglyceryl-3 polyricinoleate) Sympatens-0 / G 2500 (sorbitan stearate, methyl glucose sesquistearate), Symbio ^® muls WO Dr. Straetmans (polyglyceryl-3 polyricinoleate, sorbitan sesquioleate, cetyl ricinoleate, glyceryl caprate, cera alba, magnesium stearate, aluminum stearate), Ecomuls 2 in 1 from Natura-Tec (glyceryl oleate, polyglyceryl-3-polyricinoleate, olea europaea (olive) oil unsaponifiables), HIPEgel Olea from Alchemy (glycerin, isopropyl palmitate, water sucrose stearate, sucrose laurate).

The emulsifying composition according to the invention also makes it possible to obtain interesting sensory effects, such as a particular texture or a sensation of freshness, according to the proportions used.

The interesting properties of said emulsifying composition result from the combination of the two compounds used which exhibit good synergy both in terms of emulsion stability and sensory properties. Although very satisfactory results are obtained irrespective of the proportions in which these compounds are associated, particularly convincing results are obtained when they are combined in a very precise ratio.

In particular, each of the various constituents of the present emulsifying composition according to the invention can be integrated in a different phase, before it is carried out in emulsification. Alternatively, the various compounds of the present composition according to the invention are mixed together to form what will be referred to hereinafter by the term premix, said premix may be added to one or the other of the two immiscible phases for allow the formation of an O / W emulsion. The invention advantageously allows these two embodiments with the same compounds, which allows an increased margin of maneuver and simplified use.

Such an emulsifying composition according to the invention has the advantage of being completely of natural origin, and of being usable according to a cold process and in particular at room temperature. Said composition according to the invention is for cosmetic use and, as such, is not sensitive to reasonable pH variations or medium salinity, is not irritating and is not likely to cause allergies, in particular skin. In addition, the composition according to the invention can be used to produce any type of emulsion, including Pickering type emulsions, and is therefore suitable for a wide variety of purposes: creams, milks, serums, lotions, etc. The emulsifying composition according to the invention makes it possible to produce Pickering-type emulsions which can advantageously be stabilized by organic particles compatible with the skin or the hair. It may additionally comprise other products capable of forming or stabilizing Pickering emulsions such as silicas and octenylsuccinates starches in the form of calcium or aluminum salts.

Preferably, the emulsifying composition also comprises at least one polyol.

The polyols referred to by the present application are all the polyols known elsewhere, and in particular maltitol, mannitol, xylitol, erythritol, sorbitol, glycerol, glycerol and sorbitol being the preferred polyols. Preferably, this polyol is crystallized or is in the form of a powder.

The emulsifying composition, especially for cosmetic use and suitable for obtaining an oil-in-water (O / W) type emulsion according to the present invention may comprise in particular:

1) from 40% to 95% of at least one cyclodextrin,

2) from 5% to 40% of at least one W / O emulsifier of natural origin, preferably chosen from a non-ethoxylated ester of polyols or at least one naturally biodegradable product in a hydrous natural medium having a Hydrophilic-Lipophilic balance ( HLB) less than 8,

3) and from 0% to 40% of at least one polyol.

In a preferred manner, this emulsifying composition according to the present invention is characterized in that it contains, in% by weight:

1) from 45% to 85% of at least one cyclodextrin,

2) from 5% to 30% of at least one W / O emulsifier of natural origin, preferably chosen from a non-ethoxylated ester of polyols or at least one naturally biodegradable product in a hydrous natural medium having a Hydrophilic-Lipophilic balance ( HLB) less than 8,

3) and from 10% to 40% of at least one polyol.

In the most preferred manner, this composition according to the present invention is characterized in that it contains, in% by weight:

1) from 40% to 80% of at least one cyclodextrin, 2) from 10% to 20% of at least one W / O emulsifier of natural origin, preferably chosen from a non-ethoxylated ester of polyols or at least one naturally biodegradable product in a hydrous natural medium having a Hydrophilic-Lipophilic balance ( HLB) less than 8.

3) and from 10% to 30% of at least one polyol.

Another subject of the present invention relates to a composition of Pickering O / W emulsion type, in particular for cosmetic use, characterized in that it contains, for 1 part by weight of at least one cyclodextrin, between 0.01 and 1 part, preferably between 0.05 and 0.5 part, more preferably between 0.10 and 0.35 part and better still between 0.15 and 0.30 part of at least one emulsifier w / o of origin natural, the latter being preferably chosen from a non-ethoxylated ester of polyols or at least one naturally biodegradable product in a natural medium hydrated having a hydrophilic-lipophilic balance (HLB) of less than 8.

The Pickering O / W emulsion composition according to the invention may also comprise a fatty phase which may be at room temperature (25 ° C.), liquid, for example vegetable oils, or solid, as in the case of waxes. . This liquid fatty phase may be of mineral, animal, vegetable or synthetic origin and be composed of hydrocarbon oils or possibly silicone oils. The term "hydrocarbon-based oil" means an oil formed essentially or even consisting of carbon and hydrogen atoms and optionally oxygen, nitrogen, which may contain alcohol, ester, ether, carboxylic acid or amine groups. and / or amide.

Preferably, this composition contains one or more liquid oils at room temperature (25 ° C.), preferably at least one non-volatile liquid oil. By nonvolatile liquid oil is meant an oil that can remain on the skin at room temperature, at atmospheric pressure for at least one hour.

The liquid fatty phase advantageously comprises one or more non-volatile oils which provide an emollient effect on the skin. There may be mentioned fatty esters such as cetearyl isononoate, isotridecyl isononoate, isostearyl isostearate, isopropyl isostearate, isopropyl myristate, isopropyl palmitate, butyl stearate. hexyl laurate, isononyl isononate, 2-ethylhexyl palmitate, 2-hexyldecyl laurate, 2-octyl decyl palmitate, myristate or 2-octyldodecyl lactate, succinate 2-diethyl hexyl, diisostearyl malate, tracetin, tricprine, caprylic / capric acid triglycerides, glycerine triisostearate, tocopherol acetate, fatty acids such as myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid or isostearic acid, the higher fatty alcohols such as oleic alcohol, vegetable oils such as avocado oil, camellia oil, hazelnut oil, tsubaki oil, cashew nut oil, argan oil, lemon soybean oil, grape seed oil, sesame oil, corn oil, wheat germ oil, rapeseed oil, sunflower oil, cottonseed oil , jojoba oil, peanut oil, olive oil and their blends, vegetable butters such as shea butter, camellia butter.

These oils may be hydrocarbon or silicone type oils such as paraffin oil, squalane, petroleum jelly, dimethylsiloxanes and mixtures thereof.

The liquid fatty phase may also optionally comprise volatile oils. By volatile oil is meant an oil capable of evaporating from the skin in less than one hour at room temperature and atmospheric pressure. The volatile oils may for example be chosen from silicone oils or triglycerides of short fatty acids to reduce the greasy feel.

Preferably, the Pickering O / W emulsion composition according to the invention contains only oils of renewable origin and in particular oils or butters of vegetable origin, preferably refined. These oils and butters agree perfectly with the emulsifier system object of the invention in the sense that they make it possible to obtain very stable emulsions with a high whiteness and an easily adjustable viscosity. The emulsifying composition according to the invention advantageously makes it possible to prepare O / W emulsions with very high oil contents. This type of oil-rich O / W emulsions is usually difficult to obtain in stable form over time with conventional emulsifiers. The oil content of the final O / W emulsion is preferably from 10 to 65% by weight, and preferably from 20 to 55% by weight. Vegetable or plant-based oils, for example sunflower oil and isopropyl palmitate, make it possible in particular to obtain stable emulsions which do not give rise to creaming or phase shift.

The composition according to the invention may furthermore comprise a rheology agent such as, in particular, a thickener of the aqueous phase, a gelling agent or a suspending agent, such as, for example, gums derived from plants such as gum arabic or Konjac gum. guar gum or their derivatives; gums extracted from algae such as alginates or carrageenans; gums from microbial fermentation such as xanthans, mannan, scleroglucans or their derivatives; cellulose and its derivatives such as carboxymethylcellulose or hydroxyethylcellulose; starch and its derivatives, in particular modified starches, in particular acetylated, carboxymethylated, octenylsuccinated or hydroxypropylated starches; synthetic polymers such as polyacrylic acids or carbomers.

Preferably, the composition according to the invention comprises a rheology agent chosen from naturally occurring plant-derived or fermentation-modified polysaccharides, optionally modified. In particular, xanthan and its derivatives make it possible to obtain O / W emulsions with very fine droplet sizes, even used at a content of less than 1% by weight of the total emulsion. The emulsions obtained by employing the emulsifying composition according to the invention preferably have a drop size of less than 10 μm. By drop size of the emulsion is meant the average diameter of the droplets of dispersed fatty phase suspended in the aqueous phase. A small drop size increases the stability of the emulsion by reducing the emulsion flocculation rate, and thus the rate of phase separation. The drop size depends on a large number of parameters and, as such, is a characteristic that should be controlled and is not intrinsic to the formulation of the emulsifier system. The size of the droplets is measured using a LEICA DMLS optical microscope at x10 magnification.

The composition according to the invention may further comprise a preservative chosen from benzyl alcohol, dehydroacetic acid and mixtures thereof.

The composition according to the invention preferably has a viscosity greater than 3000 mPas at 25 ° C, preferably greater than 5000 mPas at 25 ° C. The viscosity is measured using a Brookfield DV-11 + Pro viscometer rotated at a rate of 20 rotations per minute in contact with the product sample. The resistance of the product to this rotational motion is recorded for one minute and converted to mPascal second. For each sample, the viscosity is measured three times and the arithmetic mean of the three values is retained.

In order to characterize the sensory properties of the emulsifying systems according to the invention, sensory descriptors and a corresponding sensory evaluation protocol are used in 5 steps. These 5 steps correspond to the different phases of application of a care product: appearance, handling, spreading after 1 minute, after 2 minutes. During these 5 phases, several sensory descriptors are evaluated by a panel of evaluators who assign a score ranging from 0 to 10.

The composition according to the invention preferably has a whiteness descriptor greater than 8. The whiteness descriptor is defined by the color palette of FIG. 1. The product is examined under the lamp and compared to the color palette by a panel. appraisers.

The composition according to the invention preferably has a gloss descriptor greater than or equal to 8. The brightness is defined by the propensity of the product to reflect light.

The composition according to the invention preferably has a spreading descriptor greater than 8. The spreading is evaluated by examining the product after having deposited on the hand 50 to 100 ml of the product, during its spreading in 10 rotations, under a lamp. Sprawl is all the more important as there is little resistance to movement between the 5th and 10th turn on the hand.

The composition according to the invention preferably has a film-forming descriptor greater than 8. The film-forming descriptor corresponds to the propensity of the product to form a continuous film by sliding on the skin 2 minutes after 10 rotations.

Another subject of the present invention consists in a method for manufacturing a composition of the Pickering O / W emulsion type, in particular for cosmetic use, comprising the following steps: a) the dispersion in an aqueous phase of an emulsifying composition comprising at least one cyclodextrin and at least one W / O emulsifier of natural origin, the latter being present in a ratio of between 0.01 and 1 part, preferably between 0.05 and 0.5 part, more preferably between 0, 10 and 0.35 parts and more preferably between 0.15 and 0.30 parts for 1 part by weight of at least this cyclodextrin; this w / o emulsifier of natural origin can be chosen in particular from at least one non-ethoxylated fatty ester of polyols or at least one naturally biodegradable product having a hydrophilic-lipophilic balance (HLB) of less than 8,

b) the addition to the mixture obtained in step a) of a fatty phase, preferably in an amount of between 10 and 65% by weight, and preferably of the order of 20 to 55% by weight relative to the final weight of the emulsion, under mechanical agitation sufficient to allow the dispersion of the fatty phase into fine droplets in the aqueous phase and obtaining an O / W emulsion having a drop size of less than 10 .mu.m.

According to one variant, the process according to the invention for the manufacture of a Pickering O / W emulsion composition, in particular for cosmetic use, comprising the following steps: a) the dispersion in a fatty phase of an emulsifying composition comprising at least at least one cyclodextrin and at least one W / O emulsifier of natural origin, the latter being present in a ratio of between 0.01 and 1 part, preferably between 0.05 and 0.5 part, more preferably between 0.10 and 0.35 parts and more preferably between 0.15 and 0.30 parts per 1 part by weight of at least this cyclodextrin; this w / o emulsifier of natural origin can be chosen in particular from at least one non-ethoxylated fatty ester of polyols or at least one naturally biodegradable product having a hydrophilic-lipophilic balance (HLB) of less than 8; the fatty phase preferably representing between 10 and 65% by weight, and preferably of the order of 20 to 55% by weight of the final weight of the emulsion,

b) and adding the mixture obtained in step a) to an aqueous phase with sufficient mechanical stirring to allow dispersion of the fatty phase into fine droplets in the aqueous phase and obtaining an O / W emulsion having a drop size of less than 10 μm.

The invention may be better understood with the aid of the nonlimiting exemplary embodiments described below.

Example 1

The invention will be better understood with the aid of the nonlimiting exemplary embodiments described below, and on examining the appended figures: FIG. 1 represents the color pallet used for the evaluation of the whiteness descriptor; FIG. 2 is a photograph of 6 O / W emulsions obtained from emulsifying compositions according to the invention.

Six compositions are produced in the form of an O / W emulsion according to the invention, using the following protocol. The compositions of these 6 compositions are reported in Table 1. Initially, a gelling agent is dispersed in water with stirring with a deflocculating pellet at 1000 rpm. The temperature of the water is set at 40 ° C when the gelling agent is xanthan, and at 70 ° C when the gelling agent is hydroxyethylcellulose.

The beta-cyclodextrin is then wetted in glycerine and the beta-cyclodextrin / glycerine mixture is added to the water / gelling agent mixture with stirring at 1000 rpm in order to obtain an aqueous phase.

The amount of beta cyclodextrins is set at 2% or 5% by weight of the composition according to the case.

Separately, the 3-polyglyceryl diisostearate is added in sunflower oil or in isopropyl palmitate with magnetic stirring at 40 ° C. to obtain an oily phase. The oily phase is then emulsified in the aqueous phase at 40 ° C. with stirring at 1500 rpm for 15 minutes.

A preservative is added (mixture based on benzyl alcohol and dehydroacetic acid).

Table 1

Figure 2 is a photograph of the 6 O / W emulsions obtained according to the formulations given in Table 1.

It is found that all the emulsifying compositions according to the invention comprising 1% of polyglyceryl-3-diisostearate and 2 or 5% of beta-cyclodextrin make it possible to obtain stable O / W emulsions without using a standard O / W emulsifier. .

For each of these compositions, the viscosity, the size of the drops, the whiteness, the spread, the bold character, and the penetrating character are measured. The compositions may be designated indifferently by the terms samples or produced in the following of the present detailed description.

The viscosity is measured using a Brookfield DV-ll + Pro viscometer. A fixed-size mobile (mobile SP2 to SP7 used according to the viscosity levels in accordance with the instructions of the apparatus) is rotated at a speed of 20 rpm in contact with the produced sample. The resistance of the product to this rotational movement is recorded for one minute and converted to Pascal. second. For each sample, the viscosity is measured three times and the arithmetic mean of the three values is retained.

The whiteness descriptor is defined by the color scheme in Figure 1. The product is examined under the lamp and compared to the color palette by a panel of evaluators. The spreading is evaluated by examining the product after having deposited on the hand 50 to 100 ml of the product, during its spread in 10 rotations, under a lamp. Sprawl is particularly important that there is little resistance to movement between the ^5th and the ^10th round of the hand.

The fat character of the compositions is evaluated by examination under the lamp of the product, 1 minute after making 10 rotations of the product on the skin. An evaluator panel then evaluates the resistance of the product when the skin on which it has been applied is placed between the thumb and forefinger and a rubbing motion is applied. The evaluator panel also takes into account the oily or non-oily appearance of the skin.

Finally, the penetrating character of the product is evaluated by an examination under the lamp of the product two minutes after making 10 rotations of the product on the skin, by sliding over the skin. A panel of evaluators then assesses the amount of product residue recovered.

The results obtained for the 6 compositions of O / W emulsion type are shown in Table 2.

Table 2 The viscosity of the emulsions increases slightly when the concentration of beta-cyclodextrin increases: it goes from 4000 mPas with 2% beta-cyclodextrin to more than 6000 mPas with 5%. Similarly, the viscosity is higher when the thickener used is cellulose instead of xanthan: it goes from 5000 to 8000 mPas. The emulsifying compositions according to the invention advantageously make it possible to obtain a very broad range of viscosity, which can make it possible to prepare both milks and viscous creams.

The size of the drops decreases when the concentration of beta-cyclodextrin increases, it goes from 35 microns with 2% of beta-cyclodextrin to 15 microns with 5%.

It may be noted that all the O / W emulsions obtained using the emulsifying compositions according to the invention have excellent sensory properties (grades ranging from 6 to 10 according to the white, spreading, greasy and penetrating criteria).

The emulsions are less white when the oil used is sunflower oil than when the oil used is isopropyl palmitate: the descriptor is about 8.25 out of 10 in the case of sunflower oil, against 9.25 out of 10 in the case of isopropyl palmitate. However, the whiteness of the sunflower oil remains satisfactory.

Spreading is significantly easier with xanthan than with cellulose, it goes from 8.5 with cellulose to 9.75 with xanthan.

Example 2

Then 15 emulsifying compositions according to the invention comprising different percentages of beta cyclodextrin and polyglyceryl-3 diisostearate were used to prepare 15 O / W emulsions according to the conditions given in Example 1 with a fixed amount of 0.7% by weight. of xanthan and a variable amount of sunflower oil. All percentages given are percentages by weight. The different formulations made are shown in Table 3 below.

Table 3

It is found that all the emulsifying compositions according to the invention comprising between 0.1 and 2.1% of polyglyceryl-3-diisostearate and between 1.8 and 5% of beta-cyclodextrin make it possible to obtain stable O / W emulsions and this without use of a usual O / W emulsifier.

Viscosity increases significantly as the concentration of beta-cyclodextrin increases from 4000 mPas with 2.5% beta-cyclodextrin to about 6000 mPas with 4.5% beta cyclodextrins. In addition, the viscosity increases significantly when the oil concentration increases, it is 3500 mPas with 17% oil at about 6000 mPas with 35%.

The concentration of beta-cyclodextrin does not affect the size of the drops when there is 1% of polyglyceryl-3 diisostearate: it remains stable around 25 microns. On the other hand, when the concentration of polyglyceryl-3 diisostearate is increased to 2% by weight, there is a significant decrease in the size of the drops when the concentration of beta-cyclodextrin increases: it goes from about 80 microns with 2 5% beta-cyclodextrin at about 35 microns with 4.5%.

When the concentration of beta-cyclodextrin increases, the emulsion is increasingly white, from 7.5 to 10 with 2.5% beta-cyclodextrin more than 8 out of 10 with 4.5%. In addition, the emulsion is increasingly white when the concentration of sunflower oil decreases from about 8.5 to 10 with 17% by weight of sunflower oil at 7.5 out of 10 with 25% by weight. weight of sunflower oil.

Plating is significantly better (ie, easier) when the concentration of beta-cyclodextrin decreases and when that of polyglyceryl-3 diisostearate increases. Spreading is also significantly easier when the beta- cyclodextrin concentration decreases and when that of sunflower oil decreases.

After 10 days, the O / W emulsions having a content of polyglyceryl-3 diisostearate greater than or equal to 2% by weight tend to phase out at room temperature. On the other hand, O / W emulsions 4, 6 and 15 are particularly stable and have a particularly small drop size after 10 days. These compositions are therefore particularly interesting.

An emulsifying composition (called emulsifying composition 15) comprising 4.5 parts of beta-cyclodextrin and 1 part of 3-ployglyceryl diisostearate was also used in the form of a premix, that is to say in the form of an emulsifying composition prepared in advance. It makes it possible to obtain, by dispersion at 5.5% in cold water and before addition of sunflower oil, an O / W emulsions having exactly the same characteristics as the emulsion for which the beta-cyclodextrin and the 3-polyglyceryl diisostearate were introduced separately.

Different alternatives to glycerine have also been tested. Sorbitol is a particularly interesting alternative and the compositions prepared according to the same procedure but with sorbitol instead of glycerine also showed very satisfactory performance. It is also possible to choose other polyols such as maltitol, mannitol, xylitol or erythritol.

It is understood that the embodiments described are not limiting and that it is possible to make improvements to the invention without departing from the scope thereof.

Unless otherwise stated, the word "or" is equivalent to and / or. Similarly, the word "one" is equivalent to "at least one" unless the opposite is specified.

Unless otherwise stated, all percentages expressed are percentages by weight. Example 3

7 other emulsifying compositions are prepared by replacing in the emulsifying composition described in Example 2 below, the polyglyceryl-3 diisostearate by another polyglyceryl-3 diisostearate on the market or by one of the other 6 products included in the present invention. table below. All these products have an HLB of less than 8 and are used in one part for 4.5 parts of beta-cyclodextrin.

References 1 to 5 correspond to products entering compositions

emulsifiers according to the invention and reference T has an ethoxylated and non-biodegradable control product not according to the present invention.

Then 7 O / W emulsions are prepared with the emulsifying compositions used at 5.5%, retaining the formulation of Example 2 and the conditions given in Example 1.

The characteristics of the emulsions are as follows.

It is found that all the emulsifying compositions lead viscous, fine and stable emulsions contrary to the composition T.

Further tests were then carried out by retaining as emulsifying compositions compositions comprising 4.5 parts of a crystalline betacyclodextrin or 4.5 parts of amorphous beta-cyclodextrin, associated with 1 part of polyglyceryl-3 diisostearate.

It has been found that in all cases using these 5.5% emulsifying compositions, O / W emulsions with a relatively neutral pH, a stable composition after centrifugation and a particle size very much smaller than 10 microns are obtained.

Claims

An emulsifying composition, in particular for cosmetic use, capable of obtaining an oil-in-water (O / W) type emulsion, comprising:

at. at least one cyclodextrin,

b. and at least one W / O emulsifier of natural origin, the W / O emulsifier having a hydrophilic-lipophilic balance (HLB) of less than 8.

2. Emulsifying composition according to claim 1, characterized in that the W / O emulsifier of natural origin is present in the emulsifying composition in a ratio between 0.01 and 1 part, preferably between 0.05 and 0 5 parts, more preferably between 0.10 and 0.35 parts and more preferably between 0.15 and 0.30 for 1 part by weight of cyclodextrin.

3. An emulsifier composition according to claim 1 or 2, wherein said at least one cyclodextrin is selected from alpha-, beta- and gamma-cyclodextrin, preferably from native beta-cyclodextrin.

An emulsifying composition according to claim 1, 2 or 3, wherein the cyclodextrin is in the form of a crystalline, pseudocrystalline or amorphous powder.

5. Emulsifying composition according to any one of claims 1 to 4, wherein the W / O emulsifier of natural origin is selected from non-ethoxylated fatty esters of polyols, in particular from fatty esters of glycerol, polyglycerols, sorbitol, sorbitan, anydrodrohexitols, preferably from the fatty esters of isosorbide, mannitol, xylitol, erythritol, maltitol, sucrose, glucose, polydextrose, hydrogenated glucose syrups, dextrins and hydrolysed starches.

6. Emulsifying composition according to any one of claims 1 to 5, wherein the W / O emulsifier of natural origin is selected from non-ethoxylated fatty esters of polyols obtained from fatty acids or by trans-esterification to from oil or oil mixtures.

An emulsifier composition according to claim 6, wherein said fatty acids comprise from 8 to 22 carbon atoms, preferably from 10 to 18 carbon atoms, and in particular from 12 to 18 carbon atoms.

8. emulsifying composition according to any one of claims 1 to 7 wherein the W / O emulsifier of natural origin is also selected from naturally biodegradable products in natural medium hydrated with a balance Hydrophilic-Lipophilic (HLB) between 1 , 5 and 6, preferably between 2 and 5 and more preferably between 3 and 5.

9. Emulsifying composition according to any one of claims 1 to 8, wherein the W / O emulsifier of natural origin is selected from polyglycerol esters and preferably from the esters derived from the reaction of polyglycerols comprising from 2 to 12 units of glycerol with at least one partially hydrogenated or non-hydrogenated vegetable oil of iodine number between 1 and 15.

10. An emulsifier composition according to claim 9, the W / O emulsifier of natural origin being polyglyceryl-3 diisostearate.

11. Emulsifying composition according to any one of claims 1 to 10 further comprising at least one polyol; preferably chosen from maltitol, mannitol, xylitol, erythritol, sorbitol, glycerol.

12. Emulsifying composition according to any one of claims 1 to 11, in which the composition contains:

at. 40% to 95% of at least one cyclodextrin,

b. From 5% to 40% of at least one W / O emulsifier of natural origin, preferably selected from a non-ethoxylated polyol ester having a Hydrophilic-Lipophilic Balance (HLB) of less than 8, and

c. 0% to 40% of at least one polyol.

13. Pickering H / E emulsion-type composition, in particular for cosmetic use, characterized in that it contains, for 1 part by weight of at least one cyclodextrin, between 0.01 and 1 part, preferably between 0.15 parts. and 0.30 parts of at least one W / O emulsifier of natural origin, the latter preferably being chosen from a non-ethoxylated ester of polyols having a hydrophilic-lipophilic balance (HLB) of less than 8.

14. The composition of claim 13 containing one or more liquid oils at room temperature (25 ° C), preferably at least one nonvolatile liquid oil.

The composition of claim 14, wherein the oil content of the final O / W emulsion is from 10 to 65% by weight, and preferably from 20 to 55% by weight.

16. A composition according to any one of claims 13 to 15, further comprising a rheology agent, preferably an aqueous phase thickening agent, a gelling agent or a suspending agent.

17. Composition according to any one of claims 13 to 16 having a drop size of less than 10 .mu.m.

18. Composition according to any one of claims 13 to 17 having a viscosity greater than 3000 mPas at 25 ° C, preferably greater than 5000 mPas at 25 ° C.

19. A process for producing a Pickering O / W emulsion composition, in particular for cosmetic use, comprising the following steps: a) dispersing in an aqueous phase an emulsifying composition comprising at least one cyclodextrin and at least one W / O emulsifier of natural origin, the latter being present in a ratio of between 0.01 and 1 part, preferably between 0.15 and 0.30 parts, for 1 part by weight of at least this cyclodextrin; this W / O emulsifier of natural origin being chosen from at least one non-ethoxylated fatty ester of polyols having a hydrophilic-lipophilic balance (HLB) of less than 8,

b) the addition to the mixture obtained in step a) of a fatty phase, in an amount of between 10 and 65% by weight under mechanical stirring sufficient to allow the dispersion of the fatty phase into fine droplets in the phase aqueous solution and obtaining an O / W emulsion having a drop size of less than 10 μm.

Figure 1

Figure 2