Use as emulsion base in cosmetic or pharmaceutical formulation of composition comprising stearoyl glutamate

Abstract

To overcome the problem of developing an emulsion base having no disadvantage based on stearoyl glutamate.SOLUTION: Provided is a use, as an emulsion base in a cosmetic or pharmaceutical formulation of a composition comprising a mixture of alkali metal stearoyl glutamate and stearoyl glutamic acid, characterized in that a surfactant has a pH of between 7.8 and 9.2, when measured at 25°C in a 5% by mass solution in water, and in that the composition comprises between 0.2 g and 0.5 g of aqueous phase / g of the surfactant. Provided is a method for producing the emulsion base and the cosmetic or pharmaceutical formulation comprising the emulsion base.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the use of a stearoyl glutamate as a surfactant, i.e. a mixture of an alkali metal stearoyl glutamate and stearoyl glutamic acid, a fatty phase and an aqueous phase, as an emulsifying base in a cosmetic or pharmaceutical preparation. The present invention also relates to a cosmetic or pharmaceutical preparation comprising such an emulsifying base, and to a method for producing said emulsifying base. [Background technology]

[0002] A certain number of emulsifying bases have been developed for the cosmetic or pharmaceutical market, their purpose being to be included in cosmetic or pharmaceutical preparations in the form of an emulsion.

[0003] The applicant's document WO 2007 / 042723 describes an emulsifying base comprising jojoba wax, rice wax, candelilla wax and a wax derivative obtained by reaction of polyglycerol, which base further comprises cetostearyl alcohol, glycerol stearate and sodium stearoyl lactylate as surfactants.

[0004] Even if this base gives sufficient emulsifying properties to the composition containing it, the stability of the surfactant during storage before preparing the base, and especially the risk of hydrolysis of the lactylate group, remain problematic. Moreover, the presence of low-quality lactylate derivatives can give the emulsifier an undesirable odor.

[0005] US Patent Application Publication No. 2008 / 249192A1 discloses a method for the preparation of a compound selected from (a) esters of pentaerythritol, dipentaerythritol, and tripentaerythritol, and (b) a compound selected from esters of glycerol and C 12~24It describes an emulsifying base comprising an anhydrous wax containing at least one ester with a fatty acid, the weight ratio between (a) and (b) being 1:3 to 3:1. The base further comprises monosodium stearoyl glutamate or disodium stearoyl glutamate as a surfactant.

[0006] Commercially available products sold under the name sodium stearoyl glutamate (SSG) are ionic surfactants consisting of an acidic form (stearoyl glutamic acid) and an ionic base form (sodium stearoyl glutamate), the ratio of which varies depending on the origin or supplier of the raw materials.

[0007] Although the above evaluation and hydrolysis problems can be solved by replacing sodium stearoyl lactylate with stearoyl glutamate, it still has certain disadvantages.

[0008] The first of them is that stearoyl glutamic acid is insoluble in the fatty phase, but sodium stearoyl glutamate is also insoluble in the fatty phase and requires continuous stirring to prevent particles from precipitating, which is essential to obtain a homogeneous mixture.

[0009] This homogeneity problem makes it impossible to obtain discrete solid forms, such as pellets or flakes, that are homogeneous compositions per se. In fact, to produce pellets, it is necessary to provide a homogeneous liquid without particles in suspension using a pelletizer. Moreover, the presence of these particles can participate in closing the orifices, making pelletization impossible. Moreover, the transfer from the reactor to the pelletizer is through an unagitated transfer zone, where the SSG has a tendency to settle.

[0010] Applicants have also found that the emulsifying performance of stearoyl glutamates varies with source, making it difficult to reproduce the emulsifying power of vehicles that contain them from batch to batch or from supplier to supplier.

[0011] More precisely, the applicant has found that stearoyl glutamate, depending on its origin, does not have the same surfactant properties, resulting in formulations with different levels of viscosity and stability.

[0012] WO 2019 / 042999 describes sunscreen spray compositions that contain a mixture of four or five phases, respectively, one of which contains sodium stearoyl glutamate. Once the phases are mixed, the pH of the final cosmetic formulation is adjusted by using a Tris buffer.

[0013] US Patent Application Publication No. 2020 / 306151 describes the thickening ability of ultrafine emulsions in the presence of cellulose derivatives and nonionic surfactants to form cosmetic compositions intended to be applied to the skin. The ultrafine emulsions include sodium stearoyl glutamate. The composition includes sodium hydroxide, which is used to adjust its pH when the various phases are mixed.

[0014] French Patent Application No. 3080766A1 describes a cosmetic hair care composition comprising a wax derivative obtained by simultaneous transesterification of a mixture comprising jojoba wax and sunflower wax in the presence of polyglycerol-3. Examples 12 and 13 respectively describe a moisturizing night cream and a nourishing hair mask for hair, which contain stearoyl glutamate in addition to the wax derivative. The combination of wax and stearoyl glutamate is not described as an emulsifying base. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] International Publication No. 2007 / 042723 [Patent Document 2] U.S. Patent Application Publication No. 2008 / 249192A1 [Patent Document 3] International Publication No. 2019 / 042999 [Patent Document 4] US Patent Application Publication No. 2020 / 306151 [Patent Document 5] French Patent Application No. 3080766A1 Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention therefore proposes to overcome the problem of developing an emulsifying base based on stearoyl glutamate which does not have the above-mentioned drawbacks.

[0017] In other words, the present invention provides an emulsion base based on stearoyl glutamate, a fatty phase and an aqueous phase, Its liquid and solid forms are homogeneous; It is proposed to overcome the problem of developing an emulsifying base that has the same emulsifying performance whatever the origin of the stearoyl glutamate, i.e. that makes it possible to obtain clear emulsions from the emulsifying base without the need to readjust the pH of said emulsion, unless the final emulsion contains ingredients capable of modifying the pH, such as acids. [Means for solving the problem]

[0018] The applicant has found that a series of stirring and settling steps, in combination with the correct ratio of the aqueous phase, which allows to adjust the degree of neutralization of the stearoyl glutamate, makes it possible to achieve complete dissolution of sodium stearoyl glutamate in the fatty phase after mixing of all the components.

[0019] Applicant has also found that when the pH of the stearoyl glutamate in a 5% by weight aqueous solution is between 7.8 and 9.2, consistent emulsification performance is obtained regardless of the source of the stearoyl glutamate.

[0020] Therefore, the applicant hypothesizes that the ratio of acidic (stearoyl glutamic acid) / basic (sodium stearoyl glutamate) forms contained in the stearoyl glutamate affected the surfactant performance of the stearoyl glutamate when incorporated into an emulsion.

[0021] In other words, the present invention relates to the use of a composition comprising a fatty phase, an aqueous phase and a surfactant consisting of a mixture of an alkali metal salt of stearoyl glutamic acid and stearoyl glutamic acid as an emulsifying base in a cosmetic or pharmaceutical preparation.

[0022] The invention is characterized in that the stearoyl glutamate has a pH between 7.8 and 9.2 when measured in a 5% by weight aqueous solution at 25°C.

[0023] In other words, the Applicant has found that in order to obtain a stearoyl glutamate with strong and reproducible emulsifying properties, it is necessary to measure and, if appropriate, adjust the ratio of the acidic / basic forms of the stearoyl glutamate to obtain a pH between 7.8 and 9.2 under the above conditions.

[0024] The applicant has also found that measuring only the pH of the stearoyl glutamate, rather than that of the emulsion base, has the unexpected advantage that the pH of said base can be adjusted much more accurately. According to a first feature, the alkali metal stearoyl glutamate is a sodium or potassium salt.

[0025] In a preferred embodiment, the surfactant comprises sodium stearoyl glutamate.

[0026] According to another characteristic, the surfactant represents between 5% and 12% by weight of the emulsion base, advantageously between 7% and 9% by weight, at which surfactant concentration the emulsion base gives the best effect, in particular with regard to viscosity and stability.

[0027] These concentrations of surfactants make it possible to obtain clear emulsions from the emulsifying base without the need to readjust the pH, except in the cases already mentioned where certain components disturb the pH of the emulsion due to their acidic or basic nature.

[0028] To ensure satisfactory solubilization of the stearoyl glutamate, the aqueous phase is between 1% and 5% by weight, preferably between 2% and 3.5% by weight, of the emulsifying base. Below these values, the applicant has found that there is either not enough aqueous phase to allow complete solubilization of the stearoyl glutamate in the fatty substance, or that, although all the stearoyl glutamate is indeed solubilized, the excess aqueous phase appears at the bottom of the mixer and settles.

[0029] In practice, the composition will contain between 0.2g and 0.5g of aqueous phase per gram of surfactant.

[0030] According to the invention, the fatty phase comprises a fatty substance selected from the list comprising:

[0031] In a particular embodiment, the fatty phase comprises one or more fatty substances which are solid at room temperature and in fact have a melting point above 50°C.

[0032] Preferably, the fatty substance having a melting point above 50° C. is selected from the group comprising vegetable wax derivatives modified with fatty alcohols, partial glycerides and / or polyglycerols.

[0033] In a preferred embodiment, the fatty phase comprises a wax derivative obtained by simultaneous transesterification of a mixture comprising jojoba wax and sunflower wax in the presence of polyglycerol-3.

[0034] In practice, the wax derivative represents between 20% and 40% by weight of the fatty phase, preferably between 24% and 35%.

[0035] Advantageously, the fatty phase comprises at least one C16 ~C 18 Further included are fatty alcohols and glycerol palmitostearate.

[0036] In fact, at least one C 16 ~C 18 The fatty alcohol and glycerol palmitostearate represent, respectively, between 35% and 50% by weight of the fatty phase and between 20% and 30% by weight of the fatty phase.

[0037] In certain embodiments, assuming that the emulsion base of the present invention is homogeneous in hot liquid form (i.e., when the melting point of the fatty phase is higher than 50° C.), it can be easily pelletized into individualized solid particles and in particular into flakes or pellets having a size of 1 millimeter or more.

[0038] The present invention also relates to cosmetic or pharmaceutical preparations, in particular topical preparations, which comprise an emulsifying base as described above.

[0039] In practice, the emulsifying base will represent between 1% and 8% by weight of the composition, preferably between 2% and 5%.

[0040] The emulsion base of the invention may be implemented in any galenical formulation form that is usually used for topical application to the skin, lips or hair, in particular in cosmetic compositions in the form of oil-in-water or water-in-oil or multiple emulsions, silicone emulsions or microemulsions or nanoemulsions.

[0041] The composition may be more or less fluid and may have the appearance of a white or colored cream, an ointment, a milk, a lotion or a serum. The composition may also be contained in an aerosol and may be in the form of a foam, a spray or a stick.

[0042] The compositions may contain adjuvants commonly used in the cosmetic and dermatological fields, such as lipids, emulsifiers and co-emulsifiers, hydrophilic or lipophilic gelling agents, hydrophilic or lipophilic active ingredients, preservatives, antioxidants, solvents, fragrances, fillers, hydrophilic and lipophilic sunscreens, colorants, bases and acids, penetrating agents, or polymers.

[0043] The amounts of these various adjuvants are those conventionally used in the field under consideration, for example between 0.01% and 40% of the total mass of the composition. Depending on their nature, these adjuvants may be introduced into the oily or into the aqueous phase.

[0044] Lipids that may be used in the cosmetic composition of the invention are mineral oils, oils of animal origin (lanolin), vegetable oils, synthetic oils (isopropyl myristate, octyldodecanol, isostearyl isostearate, decyl oleate, isopropyl palmitate, caprylic / capric triglyceride) and silicone oils (cyclomethicone, dimethicone). Lipids that may be used are fatty alcohols, fatty acids, waxes, butters, hydrogenated oils and gums, especially silicone elastomers.

[0045] Examples of emulsifiers and co-emulsifiers that may be used in the cosmetic compositions of the invention and that may be mentioned are nonionic, ionic (anionic or cationic) or zwitterionic surfactants, such as esters of polyglycerol and fatty acids, esters of saccharose and fatty acids, esters of sorbitan and fatty acids, esters of fatty acids and polyoxyethylenated sorbitan, esters of fatty alcohols and PEG, esters of glycerol and fatty acids, alkyl sulfates, alkyl ether sulfates, alkyl phosphates, alkyl polyglucosides, dimethicone copolyols and citric acid derivatives.

[0046] As regards the hydrophilic gelling agents, particular mention may be made of carboxyvinyl polymers, acrylic copolymers (carbomers), such as acrylate / alkyl acrylate copolymers, 2-acrylamido-2-methylpropionic acid copolymers, polyacrylamides, polysaccharides, such as xanthan gum, guar gum, carrageenan, natural gums, such as cellulose gum and its derivatives, starch and its derivatives, and clays.

[0047] As regards the liposoluble gelling agents, mention may be made of modified clays such as bentonite, metal salts of fatty acids, silica and its derivatives, ethylcellulose, polyamides, and esters of dextrose.

[0048] The cosmetic composition may also contain active ingredients. Active ingredients that may be used in particular are depigmenting agents, moisturizing agents, antioxidants, antiseborrheic agents, anti-inflammatory agents, anti-acne agents, keratolytic and / or exfoliating agents, anti-wrinkle and firming active ingredients, drainage active ingredients, anti-irritants, emollients, weight loss agents, such as xanthan bases (caffeine), vitamins and mixtures thereof, mattifying agents, anti-ageing agents, such as retinol, and also essential oils.

[0049] Preservatives which may be used according to the invention and which may be mentioned include benzoic acid, its salts and esters, sorbic acid and its salts, parabens, their salts and esters, triclosan, imidazolidinyl urea, phenoxyethanol, DMDM ​​hydantoin, diazolidinyl urea, chlorphenesin, benzyl alcohol, dehydroacetic acid, levulinic acid and derivatives, salicylic acid and its salts, ethylhexylglycerin, organic acids such as gluconolactone.

[0050] Antioxidants that may be mentioned that may be used according to the invention include chelating agents such as EDTA and its salts.

[0051] Solvents which may be used according to the invention and which may be mentioned include water, ethanol, glycerin, propylene glycol, butylene glycol, propanediol, pentylene glycol, and hexanediol.

[0052] Fillers that may be used and mentioned according to the invention include talc, kaolin, mica, sericite, magnesium carbonate, aluminum silicate, magnesium silicate, organic powders such as nylon, PMMA, starch, and natural powders such as rice flour. Such fillers may also be chemically modified or coated to modify their properties.

[0053] Sunscreens that can be used and mentioned according to the present invention include conventionally used UVA and UVB sunscreens, such as benzophenone, butyl methoxydibenzoylmethane, octocrylene, octyl methoxycinnamate, 4-methylbenzylidene camphor, octyl salicylate, terephthalylidene dicamphor sulfonic acid, phenylbenzimidazole sulfonic acid, homosalate, 2-(4-diethylamino-2-hydroxybenzoyl)benzoate, disodium phenyldibenzimidazole tetrasulfonate, methylene bisbenzotriazolyl tetramethylbutylphenol, triazine derivatives, polysilicone-15, and drometrizole trisiloxane.Physical sunscreens, TiO2 and ZnO, coated or uncoated, in micrometer and nanometer form, can also be mentioned.

[0054] Among the coloring agents that may be used according to the invention that may be mentioned are the liposoluble coloring agents, hydrophilic coloring agents, pigments and nacres commonly used in cosmetic and dermatological compositions, and mixtures thereof.

[0055] Among the bases and acids that may be used according to the invention that may be mentioned are sodium hydroxide, triethanolamine, aminomethylpropanol, potassium hydroxide, citric acid, lactic acid and phosphoric acid.

[0056] Penetrants that may be mentioned and that may be used according to the invention include alcohols and glycols (ethanol, propylene glycol), ethoxydiglycol, alcohols and fatty acids (oleic acid), fatty acid esters, dimethylisosorbide.

[0057] The compositions according to the invention may be used as care products, as cleansing products and / or as products for making up the skin, as sun protection products or as hair care products.

[0058] The present invention also relates to a method for producing the above-mentioned emulsion base, the method comprising the steps of: - preparing the fatty phase in liquid form, - introducing the surfactants, in fact all the surfactants, into the fatty phase with stirring, - measuring the pH of the stearoyl glutamate at 5% in water at 25°C separately, i.e. independently from the fatty phase, before or after the addition of the surfactant to the fatty phase and before the addition of water; - adjusting the pH of the surfactant, where appropriate, to 5% in water at 25°C by adding base or acid, to obtain a pH between 7.8 and 9.2, adjusting the stearoyl glutamic acid / sodium stearoyl glutamate ratio; - if it is necessary to add a base or an acid, determining the mass of base or acid to be added as a function of the amount of surfactant used in preparing the emulsion base, i.e. the amount of surfactant introduced into the fatty phase; - preparing an aqueous phase by adding the mass of base or acid determined in the preceding step; - adding 0.2g to 0.5g of aqueous phase per 1g of surfactant to the fatty phase; - Alternate stirring and settling phases until the surfactant is completely dissolved.

[0059] As already emphasized, adjusting the pH of the surfactant can be made more precise by determining the mass of base or acid required and then adding said mass of base or acid in the fatty phase, rather than adjusting the pH of the emulsion base once prepared.

[0060] In an embodiment in which the melting point of the components of the fatty phase is in fact higher than 50° C., the step of preparing the fatty phase in the liquid state is carried out by heating said components to a temperature above their melting point.

[0061] According to a preferred embodiment, the stirring phase lasts between 5 and 15 minutes, preferably 10 minutes, while the settling phase lasts between 2 and 10 minutes, preferably 5 minutes.

[0062] Advantageously, the stirring and settling phases are repeated at least twice, preferably four times.

[0063] In a particular embodiment where the melting point of the fatty phase components is higher, in fact 50° C., the emulsion base is subjected to a pelletizing process.

[0064] The invention and the advantages obtained will become apparent from the following embodiments, taken in support of the attached drawings. [Brief description of the drawings]

[0065] [Figure 1] FIG. 1 (1a-1g) is a series of photographs of the products obtained at the end of various steps of the process for producing an emulsion base. [Diagram 2] FIG. 2 is a photograph of the emulsion base of the present invention in pellet form. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] Composition of emulsion base The composition of the emulsion base is reproduced in Table 1 below.

[0067] [Table 1]

[0068] Manufacturing method of emulsion base The emulsion base is prepared as follows.

[0069] The various compounds of the fatty phase are mixed and the mixture is then melted at 80° C. The liquid phase obtained is then stirred at a speed of 250 rpm for a 1 liter reactor. Figure 1a is a photograph of the phase obtained at this stage of the process.

[0070] The stearoyl glutamate is then slowly introduced into the fatty phase with continuous stirring. The mixture is stirred to allow good dispersion of the powder. The dispersion is shown in Figure 1b.

[0071] The pH of the stearoyl glutamate salt is measured separately at 5% in water at 25° C. If appropriate, the ratio of stearoyl glutamic acid / sodium stearoyl glutamate is adjusted by adjusting the pH of the surfactant at 5% in water at 25° C. by adding base or acid to obtain a pH between 7.8 and 9.2. In this case, the mass of base or acid added is extrapolated to the amount of surfactant used in preparing the emulsion base. The aqueous phase is prepared by adding the mass of base or acid determined above. The aqueous phase is then added to the dispersion in Figure 1b. The amount of aqueous phase added is between 0.2g and 0.5g per gram of stearoyl glutamate. Below 0.2g water per gram of stearoyl glutamate, there is not enough water to allow complete solubilization of the stearoyl glutamate in the fatty phase. Above 0.5g water per gram of stearoyl glutamate, all of the stearoyl glutamate is solubilized, but the excess water appears at the bottom of the mixer and settles.

[0072] In several stirring steps, solubilization of the stearoyl glutamate in the fatty phase is effected and the stirring is then stopped (rest).

[0073] Once the water is added, in this example the dispersion is stirred for 10 minutes and then allowed to settle for 5 minutes (Figure 1c).

[0074] This 10 min stirring and 5 min standing step is repeated between 1 and 4 times (Figures 1d, 1e, 1f) until a homogenous and transparent product is obtained (Figure 1g).

[0075] This homogeneous and transparent mixture can be kept in a closed container at 90° C. for 48 hours without any change in appearance or chemical composition visible to the naked eye.

[0076] Pelletization Once the emulsion base is transparent, it can be pelletized without difficulty to obtain pellets that are uniform with respect to each other and within the same pellet over the entire duration of the pelleting operation (Figure 2).

[0077] Comparative Test Three formulations are prepared, differing from each other only in the pH of the surfactant measured at 5% in water. The emulsion base is that in Table 1, after or without adjusting the pH of the surfactant to 5% in water.

[0078] The composition of the formulation is shown in Table 2. The proportions of the components are expressed as mass percentages.

[0079] [Table 2]

[0080] [Table 3]

[0081] From the above, it is clear that formulation 1, with a surfactant pH between 7.8 and 9.2 at 5% in water, has a viscosity close to 50,000 cP, which corresponds to what would be expected. The results also show that formulation 1 has a good level of stability over time.

[0082] Cosmetic Formulation Examples Anti-aging serum (anti-aging lotion)

[0083]

Table 4

[0084] Sunscreen body lotion SPF30

[0085]

Table 5

[0086] Day Cream

[0087]

Table 6

Claims

1. 1. Use of a composition containing a fatty phase, an aqueous phase and a surfactant comprising a mixture of an alkali metal salt of stearoyl glutamic acid and stearoyl glutamic acid as an emulsifying base in a cosmetic or pharmaceutical preparation, characterized in that the surfactant has a pH between 7.8 and 9.2, measured in a 5% by weight aqueous solution at 25°C, and the composition comprises between 0.2 g and 0.5 g of aqueous phase per 1 g of surfactant.

2. 2. The use according to claim 1, characterized in that the alkali metal is sodium.

3. 2. The use according to claim 1, characterized in that the alkali metal stearoyl glutamate is sodium stearoyl glutamate.

4. 4. Use according to any one of claims 1 to 3, characterized in that the surfactant represents between 5% and 12% by weight, preferably between 7% and 9% by weight, of the emulsifying base.

5. 5. Use according to any one of claims 1 to 4, characterized in that the fatty phase comprises a wax derivative obtained by simultaneous transesterification of a mixture comprising jojoba wax and sunflower wax in the presence of polyglycerol-3.

6. 6. Use according to claim 5, characterized in that the wax derivative represents between 20% and 40% by weight of the fatty phase, preferably between 24% and 35% by weight.

7. Use according to claim 5 or 6, characterized in that the fatty phase further comprises at least one C16-C18 fatty alcohol and glycerol palmitostearate.

8. 8. Use according to claim 7, characterized in that the at least one C16-C18 fatty alcohol and glycerol palmitostearate represent between 35% and 50% by weight of the fatty phase and between 20% and 30% by weight of the fatty phase, respectively.

9. 9. Use according to any one of claims 1 to 8, characterized in that the composition is in the form of individualized solid particles.

10. 10. The use according to claim 9, characterized in that the individualized particles are in the form of flakes or pellets of 1 mm or larger.

11. A cosmetic composition comprising the emulsion base according to any one of claims 1 to 10.

12. 12. The cosmetic composition according to claim 11, characterized in that the emulsifying base represents between 1% and 8% by weight of the composition, preferably between 2% and 5% by weight.

13. 1. A method for producing an emulsion base for cosmetic or pharmaceutical preparations, comprising a fatty phase, an aqueous phase and, as surfactants, a mixture of sodium stearoyl glutamate and stearoyl glutamic acid, the method comprising the steps of: - preparing a liquid fatty phase, - introducing a surfactant into the fatty phase while stirring, - measuring the pH of the stearoyl glutamate at 5% in water at 25°C separately before or after the addition of the surfactant to the fatty phase and before the addition of water to the fatty phase; - adjusting the stearoyl glutamic acid / sodium stearoyl glutamate ratio, where appropriate, by adjusting the pH of the surfactant to 5% in water at 25°C by adding a base or an acid to obtain a pH between 7.8 and 9.2; - if it is necessary to add a base or acid, determining the mass of base or acid to be added as a function of the amount of surfactant used in preparing the emulsion base; - preparing an aqueous phase by adding the mass of base or acid determined in the previous step; - adding between 0.2g and 0.5g of aqueous phase per 1g of surfactant to the fatty phase, - alternating stirring and settling phases until the surfactant is completely dissolved.

14. 14. The method of claim 13, further comprising subjecting the emulsion base to a pelletizing process.

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