EMULSIFYING COMPOSITION FOR COSMETIC USE FOR PRODUCING AN O/W PICKERING EMULSION AND PROCESS FOR PRODUCING THIS EMULSION

Abstract

The application relates to an emulsifying composition, in particular for cosmetic use, allowing an oil-in-water emulsion (O/W) to be obtained, the emulsion comprising at least one cyclodextrin and at least one O/W emulsifier of natural origin with a hydrophilic-lipophilic balance value (HLB) of more than 8. The O/W emulsifier of natural origin can be selected from alkyl polyglucosides, mixtures of at least one alkyl polyglucoside and at least one fatty alcohol, and non-ethoxylated polyol fatty esters. The application also relates to a composition of the Pickering emulsion type, in particular for cosmetic use, containing the emulsifying composition according to the invention, and to the process for preparing such a composition of the O/W Pickering emulsion type, in particular at low temperatures.

Claims

1. An emulsifying composition, in particular for cosmetic use, allowing an oil-in-water (O/W) emulsion to be obtained, the emulsion comprising: a. at least one cyclodextrin, and b. and at least one O/W emulsifier of natural origin, wherein the O/W emulsifier is selected from fatty eaters of dextrins or of hydrolyzed starches. in the form of sodium octeoylsuccinate ester. the O/W emulsifier having a hydrophilic-lipophilic balance (HLB) greater than 8, preferentially greater than or equal to 9.

2. The emulsifying composition as claimed in claim 1, characterized in that the O/W emulsifier is present in the emulsifying composition in a ratio of between 0.01 and 1 part, preferably between 0.05 and 0.5 part, more preferentially between 0.10 and 0.35 part, and even better still between 0.15 and 0.30 part, per 1 part by weight of cyclodextrin.

3. The emulsifying composition as claimed in claim 1, wherein said at least one cyclodextrin is selected from alpha-, beta-, and gamma-cyclodextrins, preferably from native beta-cyclodextrin.

4. The emulsifying composition as claimed in claim 1, wherein the cyclodextrin is present in the form of a crystalline, pseudo-crystalline or amorphous powder.

5. The emulsifying composition as claimed in claim 1, wherein the O/W emulsifier is also selected from products which are naturally biodegradable in a hydrated natural medium with a hydrophilic-lipophilic balance (HLB) of between 8 and 20, preferably between 9 and 16 and even better still between 11 and 14.

6. (canceled)

7. The emulsifying composition as claimed in claim 1 , also comprising at least one polyol, which is preferably selected from maltitol, mannitol, xylitol, erythritol, sorbitol and glycerol.

8. The emulsifying composition as claimed in claim 1, wherein the composition contains, in % by weight: a. 40% to 95% of at least one cyclodextrin, b. 5% to 40% of at least one O/W emulsifier of natural origin, wherin the O/W emulsifier is selected from fatty esters of dextrins or of hydrolyzed starches in the form of sodium octenylauccinate esters, having a hydrophilic-lipophilic balance (HLB) greater than 8, preferentially greater than or equal to 9, and c. and 0% to 40% of at least one polyol.

9. A composition of the O/W Pickering emulsion type, in particular for cosmetic use, characterized in that it contains, per 1 part by weight of at least one cyclodextrin, between 0.01 and 1 part, preferably between 0.15 and 0.30 part of at least one O/W emulsifier of natural origin, wherin the O/W emulsifer is selected from fatty esters of dextrins or of hydrolyzed starches, in the form of sodium octenylsuccinate esters having a hydrophilic-lipophilic balance (HLB) greater than 8, preferentially greater than or equal to 9.

10. The composition as claimed in claim 9, containing one or more oils which are liquid at ambient temperature (25° C.), preferably at least one nonvolatile liquid oil.

11. The composition as claimed in claim 10, wherein the oil content of the final O/W emulsion is between 10 and 65% by weight, and preferably between 20 and 55% by weight.

12. The composition as claimed in claim 9, further comprising a rheological agent, preferably a thickener for the aqueous phase, a gelling agent or a suspension agent.

13. The composition as claimed in claim 9, having a droplet size of less than or equal to 30 .Math.m, preferentially less than or equal to 10 .Math.m.

14. (canceled)

15. A process for producing a composition of the O/W Pickering 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 O/W emulsifier of natural origin, wherein the O/W emulsifier is selected from fatty esters of dextrins or of hydrolyzed starches in the form of sodium octenylsuccinate esters the latter being present in a ratio of between 0.01 and 1 part, preferably between 0.15 and 0.30 part, per 1 part by weight of at least this cyclodextrin; and having a hydrophilic-lipophilic balance (HLB) greater than 8, preferentially greater than or equal to 9, and b) the addition, to the mixture obtained in step a), of a fatty phase, in an amount of between 10 and 65% by weight, with mechanical stirring sufficient to allow the fatty phase to be dispersed as fine droplets in the aqueous phase and for an O/W emulsion which has a droplet size of less than or equal to 30 .Math.m, preferentially less than or equal to 10 .Math.m, to be obtained.

Description

EXAMPLE 1

[0100] It will be possible to understand the invention more clearly by means of the nonlimiting exemplary embodiments described below, and by examination of the appended figures: [0101] FIG. 1 represents the range of colors used for evaluating the whiteness descriptor; [0102] FIG. 2 is a photograph of 6 O/W emulsions obtained from emulsifying compositions of the invention.

[0103] Six compositions in O/W emulsion form are produced according to the invention, using the following protocol. The compositions of these 6 compositions are reported in table 1.

[0104] To start with, a gelling agent is dispersed in water, with stirring using a deflocculating blade at 1000 revolutions per minute. The temperature of the water is set at 40° C. when the gelling agent is xanthan gum, and at 70° C. when the gelling agent is hydroxyethylcellulose.

[0105] Beta-cyclodextrin is then wetted in glycerol, and the beta-cyclodextrin/glycerol mixture is added to the water/gelling agent mixture with stirring at 1000 revolutions per minute, to give an aqueous phase.

[0106] The amount of beta cyclodextrins is set at 2% or at 5% by mass of the composition, depending on the cases.

[0107] Separately, the alkyl polyglucoside Montanov 68 (INCI: cetearyl alcohol & cetearyl glucose), from the company SEPPIC, is added to sunflower oil or to isopropyl palmitate with magnetic stirring, at 40° C., to obtain an oily phase.

[0108] The oily phase is then emulsified in the aqueous phase at 40° C. with stirring at 1500 revolutions per minute, for 15 minutes.

[0109] A preservative is added (mixture based on benzyl alcohol and dehydroacetic acid).

TABLE-US-00001 % Beta-cyclodextrin Oil (30%) Emulsifier (1%) Thickener (0.7%) 1 5 Sunflower Montanov™ 68 Hydroxyethylcellulose 2 5 Sunflower Montanov™ 68 Hydroxyethylcellulose 3 2 Isopropyl Palmitate (IPP) Montanov™ 68 Hydroxyethylcellulose 4 2 Sunflower Montanov™ 68 Xanthan 5 2 Isopropyl Palmitate (IPP) Montanov™ 68 Xanthan 6 5 Isopropyl Palmitate (IPP) Montanov™ 68 Xanthan

[0110] FIG. 2 is a photograph of the 6 O/W emulsions obtained, according to the formulations given in table 1.

[0111] It is noted that all the emulsions according to the invention comprising 1% of Montanov™ 68 (cetearyl alcohol and cetearyl glucose) and 2 or 5% of beta-cyclodextrin make it possible to obtain stable O/W emulsions, using only 1 wt% of customary O/W emulsifier.

[0112] For each of these compositions, measurements are made of the viscosity, droplet size, whiteness, spreading, greasy character, and penetrative character. The compositions will be designated indiscriminately using the terms samples or product in the remainder of the present detailed description.

[0113] The viscosity is measured using a Brookfield DV—II+Pro viscometer. A spindle of fixed size (spindles SP2 to SP7, used according to the viscosity levels in accordance with the instrument setpoints) is rotated at a speed of 20 revolutions per minute in contact with the product sample. The resistance of the product to this rotational movement is recorded for one minute and converted into mPascal-second, denoted mPa.s. For each sample, the viscosity is measured three times and the arithmetic mean of the three values is retained.

[0114] The whiteness descriptor is defined by the palette of colors in FIG. 1. The product is examined under a lamp and compared with the color palette by a panel of evaluators.

[0115] The spreading is evaluated by examining the product after the placement on the hand of 50 to 100 .Math.l of the product, during its spreading in 10 rotations, under a lamp. The less the resistance to movement between the 5.sup.th and 10.sup.th turn on the hand, the greater the spreading.

[0116] The greasy character of the compositions is evaluated by examination under a lamp of product, 1 minute after having performed 10 rotations of the product on the skin. A panel of evaluators then evaluates the resistance of the product when the skin to which it has been applied is placed between the thumb and the index finger and a rubbing movement is applied. The panel of evaluators also takes account of the oily or nonoily appearance imparted to the skin.

[0117] Lastly, the penetrative character of the product is evaluated by examination under a lamp of the product two minutes after having performed 10 rotations of the product on the skin, by carrying out sliding over the skin. A panel of evaluators then evaluates the amount of product residue recovered.

[0118] The results obtained for the 6 O/W emulsion compositions are set out in table 2.

TABLE-US-00002 Viscosity in mPa.s (spindle used) Droplet size (microns) White Spreading Greasiness Penetration 1 12 120 (SP5) Less than 10 10 7 7 10 2 12 233 (SP5) Less than 10 10 7 7 10 3 4417 (SP3) Less than 10 10 8 5 10 4 4917 (SP3) From 10 to 30 9 10 7 8 5 3940 (SP3) From 10 to 20 10 10 6 10 6 4517 (SP3) From 10 to 30 9 10 9 7

[0119] The viscosity of the emulsions increases slightly when the concentration of beta-cyclodextrin increases: it goes from 3900-4900 mPa.s with 2% of beta-cyclodextrin to more than 12 000 mPas with 5%. Similarly, the viscosity is higher when the thickener used is cellulose rather than xanthan: it goes from 4500 to 12 000 mPa.s. The emulsifying compositions of the invention enable the realization, advantageously, of a very wide viscosity range, allowing the preparation both of milks and of viscous creams.

[0120] It may be noted that all of the O/W emulsions obtained using the emulsifying compositions of the invention exhibit excellent sensorial properties (scores ranging from 6 to 10 according to the criteria of whiteness, spreading, greasiness, and penetration).

[0121] The emulsions are less white when the oil used is sunflower oil than when the oil used is isopropyl palmitate (denoted IPP): the descriptor is 10 out of 10 in the case of the sunflower oil, compared to 9.33 out of 10 on average in the case of isopropyl palmitate. However, the whiteness of isopropyl palmitate remains satisfactory.

[0122] The spreading is significantly easier with xanthan than with cellulose, and goes from 7.33 with cellulose to 10 with xanthan.