EMULSIFYING COMPOSITION CONSISTING OF AN OIL-IN-WATER EMULSIFIER AND A CYCLODEXTRIN OF SELECTED PARTICLE SIZE, CAPABLE OF PROVIDING AN OIL-IN-WATER EMULSION WITH IMPROVED SENSORY EFFECTS FOR COSMETIC USE

Abstract

The present invention relates to a sensory emulsifying composition, in particular for cosmetic use, capable of making it possible to obtain an oil-in-water-type emulsion, comprising at least one cyclodextrin in the form of solid particles, said particles having a volume-average size d(4,3) measured by laser granulometry, of between 2 and 20 μm, preferably between 3 and 12 μm, and more preferably between 4 and 8 μm; and at least one emulsifier of natural origin selected from oil-in-water emulsifiers, having an HLB greater than or equal to 8, and most preferably greater than or equal to 9.

Claims

1. An emulsifying composition, preferably for cosmetic use, capable of obtaining an oil-in-water-type emulsion, comprising: a) at least one cyclodextrin in the form of solid particles, said particles having a volume-average size d(4.3) measured by laser granulometry, of between 2 and 20 μm, preferably between 3 and 12 μm, and more preferably between 4 and 8 μm, b) and at least one emulsifier of natural origin selected from oil-in-water-type emulsifiers, having a hydrophilic-lipophilic balance greater than or equal to 8, most preferably greater than or equal to 9.

2. The emulsifying composition according to claim 1, wherein the cyclodextrin particles have a volume-size distribution, measured by laser diffraction granulometry, the characteristic diameters d(10), d(50) and d(90) of which are such that: a) the diameter d(10) is of less than or equal to 5.0 μm, preferably of less than or equal to 2.5 μm, and/or b) the diameter d(50) is of less than or equal to 15.0 μm, preferably of less than or equal to 10.0 μm, and/or c) the diameter d(90) is of less than or equal to 30.0 μm, preferably of less than or equal to 25.0 μm.

3. The emulsifying composition according to claim 1, wherein the solid cyclodextrin particles have a volume-size distribution, measured by laser diffraction granulometry, having a coefficient of variation of less than or equal to 100%, preferably of less than or equal to 90%, and most preferably of less than or equal to 73%.

4. The emulsifying composition according to claim 1, wherein said at least one emulsifier of natural origin has a hydrophilic-lipophilic balance (HLB) between 8 and 20, preferably between 9 and 16, and more preferably between 11 and 14.

5. The emulsifying composition according to claim 1, wherein the average HLB of the overall emulsifying system of said composition is greater than or equal to 8, preferably greater than or equal to 9.

6. The emulsifying composition according to claim 1, wherein the emulsifier of natural origin is present in the emulsifying composition in an emulsifier/cyclodextrin ratio of between 0.01:1 and 1:1, preferably of between 0.05:1 and 0.5:1, more preferably of between 0.10:1 and 0.35:1 and even more preferably of between 0.15:1 and 0.30:1.

7. The emulsifying composition according to claim 1, wherein said cyclodextrin is selected from alpha-, beta- and gamma-cyclodextrins, preferably it is a native beta-cyclodextrin.

8. The emulsifying composition according to claim 1, wherein the emulsifier of natural origin is an oil-in-water emulsifier selected from: the alkyl polyglucosides; the mixtures of at least one alkyl polyglucoside and at least one fatty alcohol; the non-ethoxylated polyol fatty esters, in particular from the glycerol, polyglycerol, sorbitol, sorbitan, anhydrohexitol fatty esters, preferably from isosorbide, mannitol, xylitol, erythritol, maltitol, sucrose, glucose, polydextrose fatty esters, fatty esters of hydrogenated glucose syrups, dextrin fatty esters and fatty esters of hydrolyzed starches.

9. The emulsifying composition according to claim 1, wherein the emulsifier of natural origin is an oil-in-water emulsifier selected from the C12-C20 alkyl polyglucosides, with the following general formula (I): R1-O—(R2-O)p-(S)n, wherein: R1 designates a linear or branched alkyl and/or alkenyl radical having about 12 to 20 carbon atoms R2 designates an alkylene radical comprising 2 to 4 carbon atoms, p takes a value ranging from 0 to 3, and preferably equal to zero, S denotes glucose, fructose or galactose, and more preferably glucose, n denotes a value ranging from 1 to 15

10. The emulsifying composition according to claim 8, wherein the O/W emulsifier of natural origin is a mixture consisting of at least one alkyl polyglucoside and at least one fatty alcohol, preferably at least one C12-C20 alkyl polyglucoside and at least one linear or branched fatty alcohol having a total number of carbon atoms ranging from 8 to 24, and most preferably a mixture of C14-C22 fatty alcohol and C12-C20 alkyl glucoside.

11. The emulsifying composition according to claim 1, comprising: a) 40% to 95% of at least one cyclodextrin in the form of solid particles, said particles having a volume-average size d(4.3) measured by laser granulometry, of between 2 and 20 μm, preferably between 3 and 12 μm, and more preferably between 4 and 8 μm, b) 5% to 40% of at least one emulsifier of natural origin selected from oil-in-water-type emulsifiers, having a hydrophilic-lipophilic balance greater than or equal to 8, most preferably greater than or equal to 9, c) And 0% to 40% of at least one polyol.

12. A liquid emulsion, preferably an oil-in-water Pickering emulsion, wherein it contains at least one cyclodextrin in the form of solid particles, said particles having a volume-average size d(4.3) of between 2 and 20 μm, preferably between 3 and 12 μm, and more preferably between 4 and 8 μm, and at least one emulsifier of natural origin selected from oil-in-water-type emulsifiers, having a hydrophilic-lipophilic balance greater than or equal to 8, most preferably greater than or equal to 9, in an emulsifier/cyclodextrin ratio of between 0.01:1 and 1:1, preferably between 0.15:1 and 0.30:1.

13. The emulsion according to claim 12, wherein it is presented in the form of a fatty phase dispersed in an aqueous phase, said dispersed fatty phase being provided in the form of droplets with an average size of less than 30 μm, preferably of less than or equal to 10 μm.

14. The composition according to claim 12, having a viscosity higher than 3000 mPa.Math.s at 25° C., preferably higher than 5000 mPa.Math.s at 25° C.

15. A method for manufacturing a liquid emulsion, preferably an oil-in-water Pickering emulsion, comprising the following steps: a) dispersing, in an aqueous phase, an emulsifying composition comprising at least one cyclodextrin in the form of solid particles, said particles having a volume-average size d(4.3) measured by laser granulometry, of between 2 and 20 μm, preferably between 3 and 12 μm, and more preferably between 4 and 8 μm, and at least one emulsifier of natural origin selected from oil-in-water-type emulsifiers, preferably having a hydrophilic-lipophilic balance greater than or equal to 8, most preferably greater than or equal to 9, in an emulsifier/cyclodextrin ratio of between 0.01:1 and 1:1, preferably of between 0.15:1 and 0.30:1, b) adding a fatty phase to the mixture obtained in step a), in an amount of between 10 and 65% by weight, relative to the total weight of the composition, under stirring to allow dispersion of the fatty phase in the aqueous phase in the form of droplets with a number-average size of less than 30 μm, preferably less than or equal to 10 μm.

16. A combined use of a cyclodextrin in the form of solid particles having a volume-average size d(4.3) measured by laser granulometry, of between 2 and 20 μm, preferably between 3 and 12 μm, and more preferably between 4 and 8 μm, and of at least one emulsifier of natural origin selected from oil-in-water-type emulsifiers, having a hydrophilic-lipophilic balance greater than or equal to 8, most preferably greater than or equal to 9, in an emulsion for cosmetic use in order to provide said emulsion with a softer and smoother feel, and to reduce or eliminate pilling.

Description

EXAMPLES

[0112] The invention will be understood better with the help of the non-limiting example of an embodiment described hereinafter.

Example 1: Emulsion

[0113] A “reference” emulsion prepared with an emulsifying composition containing a beta-cyclodextrin marketed under the name “Beauté by Roquette® CD102” by the applicant, the volume-average diameter of which is 94.83 μm, is compared with an emulsion according to the invention, which is obtained using this same beta-cyclodextrin dry-ground beforehand to have a volume-average size d(4.3) of less than 12 μm: the beta-cyclodextrin thus obtained is qualified as “ultra-fine”. The granulometric characteristics of these two beta-cyclodextrins are presented in Table 1.

TABLE-US-00001 TABLE 1 granulometric characteristics of the beta-cyclodextrins Beta-cyclodextrin Beta-cyclodextrin according “Beauté by Roquette ® to the invention, so-called CD102” (reference) “ultra-fine” d(4.3) (μm) 94.83 11.43 d10 (μm) 21.81 2.378 d50 (μm) 85.81 9.716 d90 (μm) 182.2 22.85 CV 64.7% 72.3%

TABLE-US-00002 TABLE 2 Ingredient Type reference invention Beauté by Roquette Beta- 5% — CD102 cyclodextrin “Ultra-fine” beta- Beta- — 5% cyclodextrin cyclodextrin Sunflower Oil 30%  30%  Montanov ™ L Emulsifier 1% 1% Hydroxyethyl cellulose Thickener 0.7%.sup.  0.7%.sup. 

[0114] The two emulsions in Table 2 above are prepared according to the following protocol.

[0115] First a gelling agent is dispersed in water under stirring with a deflocculating paddle at 1000 rpm. The water temperature is set at 40° C. when the gelling agent is xanthan gum, and at 70° C. when the gelling agent is hydroxyethyl cellulose.

[0116] The beta-cyclodextrin is then wetted in glycerin and the beta-cyclodextrin/glycerin mixture is added to the water/gelling agent mixture under stirring at 1000 rpm, in order to obtain an aqueous phase.

[0117] The amount of beta cyclodextrins is set at 5% by weight of the composition. Separately, the MONTANOV L alkyl polyglucoside (INCI: cetearyl alcohol & cetearyl glucose), from the company SEPPIC, is added to sunflower oil or to isopropyl palmitate under magnetic stirring, at 40° C. in order to obtain an oily phase.

[0118] The oily phase is then emulsified in the aqueous phase at 40° C. under stirring at 1500 rpm, during 15 minutes.

[0119] A preservative (mixture based on benzyl alcohol and dehydroacetic acid) is added.

[0120] For each of the emulsions, physical-chemical characteristics are measured, namely viscosity and average droplet size, and sensory characteristics are measured, namely slipperiness, spreadability, greasiness, softness, squeakiness, penetrability, smoothness and pilling.

[0121] Viscosity is measured using a Brookfield DV-II+Pro viscometer. A fixed-size moving part (SP2 to SP7 moving parts used according to the viscosity levels following device instructions) is rotated at a speed of 20 rpm in contact with the product sample. The resistance of the product to this rotational movement is recorded during one minute and converted into millipascal-second. For each sample, the viscosity is measured three times and the arithmetic mean of the three values is taken. A spindle adapted to the measured viscosity is selected according to the following ranges: the selected spindle is the SP3 spindle when the viscosity is less than or equal to 5000 mPa.Math.s, SP4 when the viscosity is between 5000 mPa.Math.s and 7000 mPa.Math.s and SP5 when the viscosity is greater than or equal to 7000 mPa.Math.s.

[0122] The average size of the droplets is determined by carrying out the arithmetic mean of the droplet sizes measured with an optical microscope at ×10 magnification, on a representative number of droplets, typically at least 10 droplets. The microscope used is a LEICA DMLS.

[0123] The sensory characteristics are evaluated by a panel of ten people who are experts in analyzing the texture of cosmetic products.

[0124] When spreading the product, two descriptors are evaluated. The product is examined under a lamp, after having placed 50 to 100 μl of the product under examination on the hand, while it is spread for 10 turns. [0125] The smoothness descriptor is evaluated between the 2nd and 5th turn. The fingers slide well over the skin. The product is perceived as a powdery substance on the skin. [0126] Spreading is evaluated by examining the product after having placed 50-100 μl of the product on the hand, while it is spread for 10 turns, under a lamp. Spreading is highest when there is little resistance to movement between the 5th and the 10th turn on the hand.

[0127] The last descriptors are evaluated after the 10 turns have been completed. For the following two descriptors, the examination is carried out under a lamp, on the skin, 1 minute after spreading 50 to 100 μl of the product. [0128] The softness descriptor is evaluated by sliding over the skin, a dry and slippery sensation is felt. [0129] The squeakiness descriptor is evaluated by rubbing the thumb with the index finger, resistance is felt, and a squeaky sound is heard.

[0130] For the following two descriptors, the examination is carried out under the lamp, on the skin, 2 minutes after spreading 50 to 100 μl of the product. [0131] The penetration descriptor of the product is evaluated by sliding over the skin. A panel of evaluators then evaluates the amount of product residue recovered. [0132] The pilling is evaluated by carrying out a mechanical rubbing action on the skin, the product leads to the formation of pills.

[0133] The two emulsions have substantially equal viscosities, around 12,000 mPa.Math.s, and have droplet sizes of less than 10 μm.

[0134] Table 3 presents the sensory perceptions obtained with the emulsion prepared with the emulsifying composition according to the invention, compared with the sensory perceptions obtained with an emulsion prepared with a reference emulsifying composition.

[0135] The criteria for improved sensory properties in the emulsion according to the invention are: smoothness, spreading, greasy, soft, squeaky, penetrating, pilling.

TABLE-US-00003 TABLE 3 improved sensory perceptions with respect to the reference emulsion Emulsion according to the invention, Sensory with ultra-fine beta-cyclodextrin, perception compared with the reference emulsion Smooth Smoother Spreading Easier Softness Softer feel Squeaky Notably less squeaky Penetrating Faster penetration Pilling No pilling or less pilling