Method for producing free powder particles of polyamide impregnated with at least one cosmetic or pharmaceutical agent, and free powder particles of polyamide having a content of at least 25 WT % of a cosmetic or pharmaceutical agent other than water

Abstract

The invention relates to a method for producing free powder particles of polyamide, impregnated with at least one cosmetic or pharmaceutical agent. The present invention also relates to free powder particles of polyamide having a content of at least 25% by weight of a cosmetic or pharmaceutical agent other than water, to the use of said particles in a cosmetic, pharmaceutical or perfumery products, and to compositions containing such particles.

Claims

1. A particle consisting of free polyamide-based powder, and at least one cosmetic or pharmaceutical agent other than water, in a solubilizer, said particle being porous, with an SSA of greater than 8 m.sup.2/g and a content of at least 40% by weight of said at least one cosmetic or pharmaceutical agent other than water, wherein the cosmetic or pharmaceutical agent is in the form of a pure liquid or as a solid dissolved in a solubilizer containing no solvent harmful to the skin, said solubilizer consisting of purified water, thermal water, glycerol, propylene glycol, a glyceride or an essential oil, said polyamide-based particle having a content, as molar percentage, of polyamide 12 of at least 50%, said cosmetic or pharmaceutical agent consisting of lactic acid, a ceramide or a mixture thereof.

2. The particle as claimed in claim 1, in which said particle has a mean diameter by volume within the range from 3 to 12 μm.

3. The particle as claimed in claim 1, in which said polyamide-based particle is particles of polyamide, copolyamide, copolyesteramide or their mixtures.

4. The particle as claimed in claim 1, in which said particle of polyamide-based powder is obtained at least in part by anionic polymerization, by seeding with an inorganic or organic filler, of lactam(s) and/or lactone(s) in solution and/or in suspension in an organic liquid.

5. The particle as claimed in claim 1, in which said particle is spheroidal.

6. The particle as claimed in claim 1, in which said at least one cosmetic or pharmaceutical agent is a compound having a chemical formula identical to that of a skin compound.

7. The particle as claimed in claim 1, in which said at least one cosmetic or pharmaceutical agent results from biofermentation.

8. The particle according to claim 1, wherein the solubilizer is glycerol, propylene glycol, or a triglyceride.

9. A cosmetic, pharmaceutical or perfumery composition, comprising the particle of claim 1.

10. The cosmetic, pharmaceutical or perfumery composition as claimed in claim 9, said composition being a colored, colorless or transparent product selected from the group of products consisting of: makeup products for the human face and body, foundation, tinted cream, loose powder, compact powder, eye-shadow, mascara, eyeliner, lipstick; care products for the human face and body, cream, milk, lotion, mask, scrubbing product, cleansing and/or makeup removing products, deodorants, antiperspirants, shaving products, hair-removing products; hair products, shampoos, product for the shaping of the hair, products for retaining the hairstyle, antidandruff products, products for combating hair loss, products for combating dryness of the hair, hair dyes, bleaching products; perfumery products, fragrance, milk, cream, and loose or compact scented powder.

11. The cosmetic, pharmaceutical, or perfumery composition of claim 9 having an enhanced and/or prolonged diffusion into the stratum corneum after topical application of said product to the skin.

12. A process for the manufacture of particles of free polyamide-based powder impregnated with at least one cosmetic or pharmaceutical agent according to claim 1, said process comprising the following successive stages: adding dropwise or by spraying said cosmetic or pharmaceutical agent in the liquid state to particles of free polyamide base powder with stirring, so that said cosmetic or pharmaceutical agent represents at least 40% by weight of the powder particles, said particles being porous and having a specific surface area (SSA) of greater than 8 m.sup.2/g wherein the cosmetic or pharmaceutical agent is in the form of a pure liquid or as a solid dissolved in a solubilizer containing no solvent harmful to the skin, said solubilizer consisting of purified water, thermal water, glycerol, propylene glycol, a glyceride or an essential oil, said polyamide-based particle having a content, as molar percentage, of polyamide 12 of at least 50%, said cosmetic or pharmaceutical agent consisting of a lactic acid, a ceramide or a mixture thereof, stopping the addition before the powder particles begin to agglomerate, maintaining the stirring for at least 5 minutes, then recovering the free powder obtained impregnated with said cosmetic or pharmaceutical agent.

13. The process as claimed in claim 12, in which said at least one cosmetic or pharmaceutical agent is liquid at the temperature at which the addition is carried out.

14. The process as claimed in claim 12, in which said particles have a mean diameter by volume within the range from 3 to 12 μm.

15. The process as claimed in claim 12, in which said polyamide-based particles are chosen from particles of polyamide, copolyamide, copolyesteramide and their mixtures.

16. The process as claimed in claim 12, in which said particles of polyamide-based powder are obtained at least in part by anionic polymerization, by seeding with an inorganic or organic filler, of lactam(s) and/or lactone(s) in solution and/or in suspension in an organic liquid.

17. The process as claimed in claim 12, in which said particles are spheroidal.

18. The process as claimed in claim 12, in which said particles comprise water.

19. The process as claimed in claim 12, in which said at least one cosmetic or pharmaceutical agent comprises a compound with a chemical formula identical to that of a skin compound.

20. The process as claimed in claim 12, in which said at least one cosmetic or pharmaceutical agent results from biofermentation.

Description

EXAMPLES

(1) The following examples illustrate the present invention without limiting the scope thereof in the examples, unless otherwise indicated, all the percentages and parts are expressed by weight.

Example 1: Impregnation Process According to the Invention

(2) Device:

(3) Use is made of a mixing reactor equipped: with a stirrer-wall scraper, a disperser-lump breaker, a system for regulating the temperature, a system which make it possible to operate under vacuum (vacuum pump, nitrogen trap), and with flushing with an inert gas, such as nitrogen (optional according to the cosmetic or pharmaceutical agents).

(4) Preparation of the Powder:

(5) The powder is introduced into the reactor; the vacuum is applied in order to degas the powder (30 mm of mercury); the powder is stirred (60 rev/min) and the vacuum is maintained for 30 minutes; the reactor is isolated.
Preparation of the Active Material:

(6) According to the nature of the cosmetic or pharmaceutical agent, it is or is not necessary to carry out a solubilization. If the cosmetic or pharmaceutical agent is liquid, relatively non-viscous and sufficiently wetting it can be directly impregnated on the powder. If not, it has to be dissolved, just like the solid agents, in a solubilizing agent, as described above, exhibiting cosmetic properties, such as purified water, thermal water, glycerol, propylene glycol, glycerides, essential oils, and the like. It is preferable to limit the amount of solubilizing agent to typically from 2 to 3 times the volume of cosmetic or pharmaceutical agent.

(7) Impregnation of the Active Material:

(8) The solution of active principle is introduced dropwise into the reactor, the powder continuing to be stirred. The optimum degree of impregnation is reached when the powder particles remain free and retain their initial flowability, that is to say retain the sane particle size distribution as before impregnation. They must not begin to agglomerate. For unstable and oxidation-sensitive active principles, the introduction is carried out while flushing with nitrogen. Once the introduction has been completed, the powder continues to be stirred for 30 minutes.

(9) In order to prevent caking of the powder, it is possible to use a disperser or other equivalent rapid-stirring systems.

(10) Particles of free powder are obtained which are highly charged with cosmetic or pharmaceutical agent(s).

Example 2: Particles of Free Powder Comprising a High Content of Cosmetic or Pharmaceutical Agent(s) According to the Invention

(11) TABLE-US-00001 TABLE 1 Example 2.1 Example 2.2 Cosmetic or Ceramide-3 Lactic acid pharmaceutical agent Powder particles Copolyamide PA 6/12 Polyamide PA12 (20%/80% in moles)-10 μm 5 μm SSA > 8 m.sup.2/g SSA > 8 m.sup.2/g Solubilizing agent Olive glycerides Water Drying no no Content of cosmetic 25% (Ceramide-3 + Olive 40% lactic acid agent(s) in the glycerides) particles of free powder Function of the agent Anti-aging, Exfoliant, restores the horny layer greasy skin regulator

(12) The PA6/12 and PA12 powder particles respectively used for the manufacture of the impregnated particles of free powder of examples 2.1 and 22 are spheroidal particles of the Orgasol® brand; the diameter shown in μm is the mean diameter by volume. The particles of PA6/12 are obtained according to the process described in the document WO 2008/087335, and the particles of PA12 are obtained according to the process described in the document EP 0 192 515.

(13) The impregnated particles of free powder of examples 2.1 and 2.2 according to the invention respectively have the same particle size and the same specific surface as the PA 6/12 and PA12 powder particles respectively not impregnated with cosmetic agent. In example 2.1, the solubilizing agent for the ceramide-3 results from mixtures of triglycerides, diglycerides and monoglycerides, obtained by esterification of fatty acids of vegetable origin (olive oil in particular). This solubilizing agent is a lipophilic compound which exhibits a high affinity for the skin and which exhibits a light and non-greasy feel. In addition to its cosmetic properties, this solubilizing agent is used according to the invention to solubilize cosmetic agents which ma particularly difficult to solubilize, such as ceramides, in particular ceramide-3. The process according to the invention thus makes it possible to introduce, into porous particles of free powder, ceramides which will subsequently be genuinely available for the upper layers of the epidermis. The effectiveness of these particles according to the invention is demonstrated (see tests of effectiveness in example 4.1) in a foundation composition formulation (see example 3.1).

(14) In example 2.2, the lactic acid results from biofermentation. In these particles of free powder according to the invention, the combination of lactic acid resulting from biotechnology and of porous particles predominantly comprising polyamide 12 makes it possible to increase the effectiveness of the cosmetic product which comprises them, in particular by virtue of the high content of lactic acid particles (40% instead of 20% in the impregnated particles of the prior art). Tests of effectiveness of these particles show that there is a synergy between the porous powders predominantly comprising polyamide 12 and lactic acid with regard to the control of the sebum at the surface of the skin. The effectiveness of these particles according to the invention is demonstrated (see tests of effectiveness in example 4.2) in a makeup-removing milk composition formulation (see example 3.2).

(15) Finally, the particles according to the invention (examples 2.1 and 2.2) do not comprise any trace of solvent harmful to the skin.

(16) The particle size distribution of the powders in the present description, in particular in the examples and comparative examples, is measured using a particle sizer of Coulter LS230 brand. It makes it possible to obtain the particle size distribution of the powders, from which it is possible to determine the mean diameter and the width of the distribution or the standard deviation of the distribution. The particle size distribution of the powders according to the invention is determined according to the usual techniques using a Coulter LS230 particle sizer from Beckman-Coulter. It is possible, from the particle size distribution, to determine the mean diameter by volume with the logarithmic calculation method, version 2.11a of the software, and the standard deviation, which measures the narrowing in the distribution or the width of the distribution around the mean diameter.

Example 3: Compostions Comprising Particles According to the Invention

Example 3.1: Manufacture of a Cast Foundation According to the Following Formulation

(17) TABLE-US-00002 TABLE 2 Phase INCI % A Arachidyl alcohol, Behenyl alcohol, 2.00 Arachidyl glucoside Cetyl palmitate 0.50 Cetearyl alcohol 0.30 C.sub.18-21 Alkane 4.00 C.sub.13-15 Alkane 2.00 Neopentyl glycol diheptanoate 3.00 Dimethicone 1.50 Polyglyceryl-3 diisostearate 1.00 Ethylhexyl methoxycinnamate 4.00 Butylmethoxydibenzoylmethane 0.50 B Aqua q.s. for 100 EDTA 0.1 Glycerol 2 Methylpropanediol 4 Magnesium aluminum silicate 0.4 Cetearyl sulfate 0.2 Xanthan gum 0.15 C Mica 1.5 CI77499 0.1 CI77491/2/9 0.4 CI77492 1.5 CI77891 6 D Example 2.1 3.00

(18) The Ingredients of phase A are weighed out, charged to a melting pot and heated at 110-115° C., while mixing at a constant rate. It is confirmed that the phase is homogeneous and then it is cooled to 85-90° C. The ingredients of phase B are then added one by one while continuously mixing. Before continuing, it is confirmed that the mixture is homogeneous. During this time the powders of phase C are mixed. Phase C is then added to the melting pot while mixing at a constant rate until the combined mixture is homogeneous. The temperature is maintained at 85-90° C. The ingredients of phase D are added one by one and mixing is carried out at a constant rate until the combined mixture is homogeneous. Casting is carried out in appropriate metal molds while maintaining the mixture at 85° C. After cooling, a cast foundation is obtained.

Example 3.2: Composition of a Makeup-Removing Milk According to the Present Invention with D and not According to the Present Invention with D1 or D2

(19) TABLE-US-00003 TABLE 3 Phase INCI % A Aqua q .s. for 100 Disodium EDTA 0.15 Hydroxypropyl guar 0.05 Xanthan gum 0.15 Glycerol 3.00 B PEG 8 stearate - cetearyl ethylhexanoate - 8.00 isopropyl myristate - glyceryl stearate - stearyl heptanoate - cetyl alcohol - butyl stearate - cetyl palmitate - sorbitan sesquioleate - stearic acid - aqua - potassium hydroxide - BHA Cetearyl alcohol 1.50 Butyrospermum parkii butter 2.00 Isononyl isononanoate 4.00 Macadamia ternifolia seed oil 8.00 β-Sitosterol 0.20 Phenoxyethanol - methylparaben ethylparaben - 0.80 butylparaben propylparaben - isobutylparaben C Aqua 5.00 Imidazolidinyl urea 0.30 Sodium cocoamphoacetate 2.00 D For example Particles of free powder of example 2.2 2.00 3.2 Nylon 11 (Rilsan T NAT BHV COS) 2.00 or D1 For Polyamide PA12 (5 μm, SSA > 8m.sup.2/g) 1.20 comparative (Orgasol ®) example 1 Lactic acid 0.80 Nylon 11 2.00 or D2 For Nylon 11 2.00 comparative example 2

(20) All the components of phase A are mixed. Phase B is added with stirring, followed by phases C and D (or D1 or D2) in succession. The pH of the makeup-removing milk obtained is controlled.

Example 4: Tests of Effectiveness on a Composition According to the Invention

(21) The compositions of example 3 are tested by panels of trained experts.

Example 4.1

(22) The composition of example 3.1 according to the invention (cast foundation) is compared with a placebo composition (comparative example 3) in which the particles of free powder according to the Invention have been replaced by the same content of tale (3%). The imperceptible water loss (also known as transepidermal water loss (TEWL)) obtained after use of these two compositions is compared. The transepidermal water is that which diffuses through the skin before coming back up to its surface. It then evaporates therefrom and is lost. The more damaged the horny layer, the greater the imperceptible water loss.

(23) The well-known method of the Tewameter®, by means of a Tewameter® 300 device (Courage+Khazaka electronic GmbH), is used.

(24) TABLE-US-00004 TABLE 4 Measurement of the variation (%) in After After After After transepidermal water loss 7 days 15 days 30 days 60 days (TEWL) of use of use of use of use Comparative example 3 −1% −2%  −3%  −3% Example 3.1 −6% −8% −10% −12%

(25) The daily application to the face of the composition of example 3.1 results in an improvement of the barrier function of the skin, which is characterized by a decrease in the imperceptible water loss TEWL of 12% after 60 days of use of the foundation of example 3.1. The reduction in TEWL is only 3% for the same placebo foundation composition not comprising particles according to the invention (comparative example 3).

(26) The level of sebum obtained after use of these two compositions (comparative example 3 and example 3.1) is compared by the Sebumeter® method using a sebumeter of Sebumeter® 815 brand, Courage+Khazaka GmbH.

(27) TABLE-US-00005 TABLE 5 Measurement of the After After After After variation (%) in the level 7 days 15 days 30 days 60 days of sebum of use of use of use of use Comparative example 3 +2% +2%  +3%  +3% Example 3.1 +4% +8% +14% +18%

(28) The daily use of the composition of example 3.1 continuously improves the hydrolipidic film of the skin, as is shown by the change in the level of sebum. For comparative example 3, the level of sebum remains unchanged.

(29) The variations in the parameter “smooth appearance of the skin” obtained after use of these two compositions (comparative example 3 and example 3.1) are compared by the method of skin surface evaluation by mean of a Visioscan VC 98 device (Courage+Khazaka electronic GmbH) used for the in vivo and 3D analysis of the surface of the skin. The parameter measured by the image analysis is the SESm (skin smoothness) which is calculated from the mean wrinkle width and the mean wrinkle depth. The lower the value of SESm, the smoother the appearance of the skin.

(30) TABLE-US-00006 TABLE 6 Measurement of the variation (%) in the After After After After parameter “smooth 7 days 15 days 30 days 60 days appearance of the skin” of use of use of use of use Comparative example 3 +3%  +5%  +6%  +6% Example 3.1 +8% +11% +12% +14%

(31) The use of the foundation of example 3.1 according to the invention increases the smooth appearance of the skin by 14% after 60 days of daily use. According to the nature of the skin, the increase in the smoothness of the akin can reach 30% with the composition of example 3.1 according to the invention. The placebo formulation (comparative example 3) improved the smooth appearance of the skin by only 6%, a plateau reached after 30 days.

(32) The impregnated particles according to the invention (example 2.1) have a long term effectiveness with regard to the reduction of the rough appearance of the skin and with regard to the reduction in the depth of the wrinkles. FIG. 1 is a graph representing a cross section of skin through three wrinkles referenced 1, 2 and 3 (on the abscissa) with different depths (on the ordinate). The level (depth) of the wrinkles is represented before (in dark gray, 5) and after (in light gray, 6) 60 days of use of the foundation of example 3.1. It is noticed, on this graph, that the depth (6) of the wrinkles is significantly reduced after 60 days of use in comparison with the depth (5) of the wrinkles before use of the composition according to the invention, to approach the surface (4) of the skin (represented by a horizontal line on the top part of the graph).

Example 4.2

(33) The composition of example 3.2 according to the invention (makeup-removing milk) is compared with two compositions: a composition, referred to as comparative example 1, in which the particles of free powder which are charged with cosmetic agent (lactic acid) of the present invention (of example 3.2) have been replaced with equivalent contents of lactic acid and of free powder based on polyamide of the same type but not impregnated with the lactic acid, a composition, referred to as comparative example 2, which does not comprise particles of free powder which are charged with cosmetic agent.

(34) The amount of sebum on the surface of the skin is measured before the application of the makeup-removing milk, then 2 hours after the first application and, finally, after a week of daily application.

(35) The amount of sebum at the surface of the skin is measured according to the well-known measurement method of the sebumeter (the reference of the sebumeter used is: Sebumeter 815, Courage+Khazaka GmbH). This is a direct measurement of the accumulation of the sebum on the skin.

(36) TABLE-US-00007 TABLE 7 Example Comparative Comparative Measurement 3.2 Example 1 Example 2 Variation (reduction in %) −30% −20% −5% in the level of sebum 2 hours after application of the makeup-removing milk

(37) The use of the makeup-removing milk of example 3.2 according to the invention reduce the sebum on the surface of the skin by at least 30%. The use of the makeup-removing milk of comparative example 1 reduces the sebum by only 20% and that of comparative example 2 reduces the sebum by only 5%.

(38) This difference in effectiveness between the makeup-removing milk compositions of example 3.2 and comparative example 1 is maintained even after storing for 6 months. This confirms the stability of the particles of free powder comprising a high content of cosmetic or pharmaceutical agent according to the invention in the formulations comprising them.

(39) The particles of free powder comprising a high content of cosmetic or pharmaceutical agent according to the invention “boost” or enhance the effectiveness of the agent present in them. Furthermore, it is noticed that the action observed for the formulations comprising particles according to the example 2.2 of the invention is not followed by a rebound effect since, after makeup removal, the level of sebum does not increase again but, on the contrary, remains stable and corresponds to the level desired for a normal skin (about 190 μg/cm.sup.2), also after 7 days of daily use of the makeup-removing milk of example 3.2, as is shown in table 8.

(40) TABLE-US-00008 TABLE 8 Before 2 hours after the After 7 days of application application of the daily use of the of the makeup- makeup-removing makeup-removing removing milk milk of example milk of example of example 3.2 3.2 3.2 Level of sebum 265 188 185 (μg/cm.sup.2) Classification greasy skin normal skin normal skin (>220) (100-220) (100-220)