Emulsified composition utilizing n-acylamino acid salt, and method for producing same

Abstract

The present invention pertains to an oil-in-water type emulsified composition that has excellent feeling of use, fine emulsion stability, and low skin irritation, the method comprising (1) a step for stirring (a) 0.1-10 mass% of an acylamino acid salt having an acyl group that has 16-22 carbon atoms and (b) 1-50 mass% of an oil phase component to disperse (a) in (b), and (2) a step for adding, to the obtained mixture, (c) an aqueous phase component and stirring the same.

Description

Emulsion composition using N-acyl amino acid salt and method for producing the same

[0001] The present invention relates to an oil-in-water emulsion composition having excellent emulsion stability and low skin irritation, and a method for producing the same.

[0002] Generally, as an emulsification technique used in cosmetics and the like, a surfactant is dissolved in water, and an oil phase component is added while stirring with a homomixer or the like to emulsify the oil phase component. In recent years, formulations with higher safety and free from petroleum-derived components are preferred. Furthermore, in order to reduce stickiness in terms of usability, an emulsion composition with reduced oil droplet size to the nano size is preferred. For example, high-pressure emulsification is known as a method for obtaining nano-sized emulsified particles (Patent Document 1). On the other hand, N-stearoyl glutamate is known for its high safety and being plant-derived, but its emulsifying power is insufficient when used alone and it has often been used in combination with other surfactants (Patent Document 2). However, with respect to the problem of emulsifying power, it has been reported that a gel obtained by rapidly cooling an aqueous solution of N-stearoyl glutamate can emulsify a large amount of oil (Patent Document 3).

[0003] Japanese Patent No. 4255078 JP-A-2023-73433 Japanese Patent No. 3261807

[0004] Industrially, it is difficult to rapidly cool a large amount of aqueous solution or the like, and it has been difficult to apply it in ordinary cosmetics production. Furthermore, since the usability changes depending on the type of oil component and the oil droplet size, the selection of the oil component and the control of the oil droplet size are very important for obtaining a desired cosmetic. The present invention has been made in view of the above circumstances, and an object thereof is to provide an oil-in-water emulsion composition having excellent usability, good emulsion stability, and low skin irritation, and a method for producing the same.

[0005] The inventors of the present invention conducted diligent research to solve the above problems and found that an oil-in-water emulsion composition obtained by stirring and dispersing N-stearoyl glutamate in oil to reduce the particle size of N-stearoyl glutamate, and then adding an aqueous phase component to the dispersion, has excellent usability and low skin irritation. Furthermore, the obtained emulsion composition also has excellent emulsion stability, and by emulsifying it under high pressure, the oil droplet size can be further reduced to nanoscale, and the usability can be controlled accordingly, leading to the completion of the present invention.

[0006] In other words, the present invention relates to the following: [1] A method for producing an oil-in-water emulsion composition, comprising the steps of (1) stirring 0.1 to 10% by mass of an acyl amino acid salt having an acyl group having 16 to 22 carbon atoms and 1 to 50% by mass of an oil phase component to disperse (a) in (b), and (2) adding an aqueous phase component (c) to the obtained mixture and stirring. [2] The method according to [1], further comprising the step of (3) high-pressure emulsification. [3] The method according to [1] or [2], wherein the acyl amino acid salt having an acyl group having 16 to 22 carbon atoms is N-stearoyl glutamate. [4] The method according to any one of [1] to [3], wherein the oil phase component is N-lauroyl-L-glutamic acid di(phytosteryl / 2-octyldodecyl). [5] The method according to any one of [1] to [4], wherein the average particle size of the emulsion particles of the oil-in-water emulsion composition is 1 to 500 μm. [6] The manufacturing method according to any one of [2] to [4], wherein the average particle size of the emulsion particles of the oil-in-water emulsion composition is 50 to 500 nm. [7] The manufacturing method according to any one of [2] to [6], wherein the oil-in-water emulsion composition is a microemulsion.

[0007] According to the present invention, an oil-in-water emulsion composition with excellent usability and emulsification stability, as well as low skin irritation, can be easily obtained. According to the present invention, a fine emulsion composition can be produced without heating.

[0008] Figure 1 is a micrograph of a composition obtained by heating and high-pressure emulsification of sodium N-stearoyl glutamate (HS-11) and dilauroyl glutamate (phytosteryl / octyldodecyl) (PS-203). Each micrograph was taken using a VHX-8000 manufactured by Keyence Corporation. Figure 2 is a micrograph of an emulsified composition (Example 5) obtained by manufacturing method 1 of the present invention using HS-11 and PS-203. Figure 3 is a micrograph of an emulsified composition (Example 9) obtained by manufacturing method 2 of the present invention using HS-11 and PS-203. Figure 2 shows the particle size of the emulsified compositions obtained by manufacturing methods 1 and 2, as measured by a particle size distribution analyzer LA-960V2 manufactured by Horiba, Ltd.

[0009] The present invention relates to a method for producing an oil-in-water emulsion composition, comprising the steps of (1) stirring (a) 0.1 to 10% by mass of an acyl amino acid salt having acyl groups with 16 to 22 carbon atoms and (b) 1 to 50% by mass of an oil phase component to disperse (a) in (b), and (2) adding (c) an aqueous phase component to the obtained mixture and stirring (hereinafter also referred to as Method 1 of the present invention).

[0010] In component (a), the number of carbon atoms in the acyl group is usually 16 to 22, preferably 18 to 20, and more preferably 18. The acyl group may be saturated or unsaturated. Examples include palmitoyl group, stearoyl group, oleoyl group, isostearoyl group, linolenoyl group, and behenoyl group, with stearoyl group, oleoyl group, isostearoyl group, and linolenoyl group being preferred, and stearoyl group being more preferred. The acyl group may also be derived from mixed fatty acids, such as coconut oil fatty acid acyl, palm oil fatty acid acyl, palm kernel oil fatty acid acyl, sunflower seed oil fatty acid acyl, and macadamia nut oil fatty acid acyl.

[0011] Examples of amino acids in component (a) include glutamic acid, aspartic acid, alanine, arginine, glycine, N-methylalanine, histidine, serine, threonine, and sarcosine, with glutamic acid, aspartic acid, alanine, N-methylalanine, and sarcosine being preferred, and glutamic acid being more preferred.

[0012] Examples of acyl amino acid salts in component (a) include alkali metal salts such as lithium salts, sodium salts, and potassium salts; alkaline earth metal salts such as calcium salts and magnesium salts; alkanolamine salts such as monoethanolamine, diethanolamine salt, and triethanolamine (TEA) salt; ammonium salts; and basic organic salts such as arginine salt. The degree of neutralization is in the range of 1.0 to 2.0. Among these, alkali metal salts and alkaline earth metal salts are preferred, sodium salts and potassium salts are more preferred, and sodium salts are particularly preferred.

[0013] The salts of N-acyl amino acids having an acyl group with 16 to 22 carbon atoms used in the present invention include, specifically, N-palmitoyl glutamate, N-stearoyl glutamate, and N-cocoyl (coconut oil fatty acid acyl) glutamate, N-palmitoyl aspartate, N-stearoyl aspartate, N-cocoyl aspartate, and, for example, mono or disodium salts, mono or dipotassium salts, mono or ditriethanolamine salts of the above N-acyl amino acids. These may be used individually or in combination of two or more. Among these, from the viewpoint of emulsification stability, N-palmitoyl glutamate, N-stearoyl glutamate, and N-cocoyl (coconut oil fatty acid acyl) glutamate are preferred, and sodium N-stearoyl glutamate is more preferred.

[0014] The oil phase component of component (b) is not particularly limited as long as it does not impair the effects of the present invention, but examples include hydrocarbons, liquid oils and fats, solid oils and fats, synthetic ester oils, higher alcohols, waxes and silicones.

[0015] Examples of hydrocarbons include liquid paraffin, squalane, ceresin, petrolatum, and microcrystalline wax.

[0016] Examples of liquid oils include vegetable oils such as sunflower oil, avocado oil, macadamia nut oil, corn oil, olive oil, rapeseed oil, sesame oil, wheat germ oil, castor oil, linseed oil, coconut oil, palm oil, palm kernel oil, and rice bran oil.

[0017] Examples of solid fats and oils include cocoa butter, horse fat, hydrogenated coconut oil, beef tallow, hydrogenated beef tallow, and hydrogenated castor oil.

[0018] Examples of synthetic ester oils include lauroyl glutamate diesters such as lauroyl glutamate di(phytosteryl / octyldodecyl), lauroyl glutamate di(octyldodecyl / phytosteryl / behenyl), lauroyl glutamate di(cholesteryl / behenyl / octyldodecyl), and lauroyl glutamate di(cholesteryl / octyldodecyl), as well as isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, polyglyceryl laurate, myristyl myristate, cholesteryl 12-hydroxystearate, glyceryl trioctanoate, and 2-hexyldecyl myristate.

[0019] Examples of higher alcohols include lauryl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, myristyl alcohol, oleyl alcohol, cetostearyl alcohol, glycerin monostearyl ether, hexyldodecanol, and octyldodecanol.

[0020] Examples of waxes include beeswax, candelilla wax, carnauba wax, whale wax, lanolin, and jojoba oil (jojoba wax).

[0021] Examples of silicones include dimethylpolysiloxane, methylphenylpolysiloxane, octamethylcyclotetrasiloxane, various modified polysiloxanes, and fluorine-modified polysiloxanes.

[0022] In particular, from the viewpoint of emulsification stability, hydrocarbon oils, liquid oils, synthetic ester oils, waxes, and silicone oils are preferred, hydrocarbon oils, liquid oils, and synthetic ester oils are more preferred, and liquid paraffin, vegetable oil, and lauroyl glutamate diester are even more preferred.

[0023] Examples of aqueous phase components of component (c) include the following: Aqueous phase components include water, lower alcohols, and polyhydric alcohols. Other water-soluble components that do not inhibit the effects of the present invention can be added. The water is not particularly limited as long as it can be used in food products, cosmetics, etc. Examples include purified water, sterilized water, tap water, hard water, soft water, natural water, seawater, deep-sea water, electrolyzed alkaline ionized water, electrolyzed acidic ionized water, ionized water, and clustered water.

[0024] Examples of lower alcohols include ethanol, propanol, isopropanol, isobutyl alcohol, and t-butyl alcohol.

[0025] Examples of polyhydric alcohols include propylene glycol and 1,3-butylene glycol as dihydric alcohols, glycerin as a trihydric alcohol, and sorbitol as a hexahydric alcohol. Polyhydric alcohol polymers are also included.

[0026] In particular, from the viewpoint of emulsification stability, water and polyhydric alcohols are preferred, and water, propylene glycol, 1,3-butylene glycol, and glycerin are more preferred.

[0027] The manufacturing method 1 of the present invention includes step (1) of stirring (a) and (b) to disperse (a) in (b). The mass ratio of component (a) to the total amount of the oil-in-water emulsion composition is usually 0.1 to 10% by mass, preferably 0.2 to 8% by mass, and more preferably 0.5 to 5% by mass. The mass ratio of component (b) to the total amount of the oil-in-water emulsion composition is usually 1 to 50% by mass, preferably 3 to 45% by mass, and more preferably 5 to 41% by mass.

[0028] Methods for stirring (a) and (b) include using a high-pressure emulsifier, ball mill, bead mill, disperser mixer, homomixer, etc. By stirring using these methods, (a) can be finely dispersed in the oil phase of (b), and (a) can be dispersed in (b).

[0029] The stirring conditions in step (1) are appropriately changed depending on the type and use of the oil, but for example, when using a high-pressure emulsifier, the stirring is usually performed under a pressure of 50 to 300 MPa, preferably 70 to 200 MPa, with 3 to 20 passes, preferably 5 to 15 passes, and no heating is particularly necessary, usually at 15 to 40°C. The pH of the mixture is usually 4 to 9, preferably 5 to 8. The pH can be measured by the glass electrode method in accordance with the provisions of Japanese Industrial Standards (JIS) Z 8802:2011, the 18th revised Japanese Pharmacopoeia, General Test Methods 2.54 pH Test Method, etc.

[0030] The manufacturing method 1 of the present invention includes step (2) of adding the aqueous phase component (c) to the mixture obtained in step (1) and stirring. The mass ratio of component (c) to the total amount of the oil-in-water emulsion composition is usually 30 to 97% by mass, preferably 40 to 95% by mass, and more preferably 50 to 90% by mass.

[0031] In step (2), the same method as in step (1) can be used for stirring.

[0032] The stirring conditions in step (2) are appropriately changed depending on the type and application of the aqueous phase components. For example, when using a high-pressure emulsifier, the stirring is usually performed under a pressure of 50 to 300 MPa, preferably 70 to 200 MPa, with 3 to 20 passes, preferably 5 to 15 passes, and at a temperature of 15 to 40°C. The pH of the mixture is usually 4 to 9, preferably 5 to 8. The pH can be measured by the method described above.

[0033] In the manufacturing method 1 of the present invention, the mass ratio of (a) to (b) [(a):(b)] is usually 1:0.1 to 500, preferably 1:0.4 to 250, and more preferably 1:1 to 82. In the manufacturing method 1 of the present invention, the mass ratio of (a) to (c) [(a):(c)] is usually 1:3 to 970, preferably 1:5 to 475, and more preferably 1:10 to 180. In the manufacturing method 1 of the present invention, the mass ratio of (b) to (c) [(b):(c)] is usually 1:0.6 to 97, preferably 1:0.9 to 32, and more preferably 1:1.2 to 18.

[0034] The particle size (average particle diameter) of the emulsion particles serves as an indicator of the stability and appearance of the emulsion, representing the state of the emulsion. Generally, the smaller the particle size, the more stable and transparent the emulsion composition becomes, allowing for the provision of emulsion compositions such as cosmetics with a beautiful appearance. On the other hand, if the particle size is too small, there is a tendency for instability. Therefore, the particle size (average particle diameter) of the emulsion particles of the oil-in-water emulsion composition obtained by the manufacturing method 1 of the present invention is usually 1 to 500 μm, preferably 1 to 300 μm, and more preferably 1 to 100 μm. The particle size of the emulsion particles of the emulsion composition of the present invention can be measured using a particle size analyzer that measures dynamic light scattering at 25°C after appropriately diluting the emulsion composition with purified water as needed.

[0035] The present invention also includes a method for producing an oil-in-water emulsion composition, comprising a step (3) of further high-pressure emulsification in the production method 1 of the present invention (also abbreviated as production method 2 of the present invention). By further high-pressure emulsifying the oil-in-water emulsion composition obtained in production method 1, an even finer oil-in-water emulsion composition can be obtained.

[0036] In step (3), methods for high-pressure emulsification include using a high-pressure emulsifier such as a high-pressure homogenizer, but a high-pressure emulsifier is preferred from the viewpoint of obtaining a finer emulsion. By stirring using these methods, a nanoemulsion can be obtained.

[0037] The conditions for high-pressure emulsification in step (3) are appropriately changed depending on the type and use of components (a), (b), and (c). For example, when using a high-pressure emulsifier, the process is usually carried out under a pressure of 50 to 300 MPa, preferably 70 to 200 MPa, with 3 to 20 passes, preferably 5 to 15 passes, and at a temperature of 15 to 40°C. The pH of the mixture is usually 4 to 9, preferably 5 to 8. The pH can be measured by the method described above.

[0038] As described above, the particle size (average particle size) of the emulsion particles in the oil-in-water emulsion composition obtained by the manufacturing method 2 of the present invention is typically 50 to 500 nm, preferably 50 to 300 nm, and more preferably 50 to 200 nm. The particle size of the emulsion particles can be measured by the method described above.

[0039] The oil-in-water emulsion composition obtained by the manufacturing method 2 of the present invention forms a microemulsion. A microemulsion is a solution produced by solubilization, and solubilization refers to the phenomenon in which a surfactant dissolves a substance that is not normally soluble in a solvent using aggregates such as micelles that are formed in a solvent such as water or oil. A microemulsion is a stable emulsion whose state does not change under constant temperature and pressure.

[0040] In manufacturing methods 1 and 2 of the present invention, steps may be taken to add components other than those listed above, to the extent that they do not hinder the objective of the present invention. Examples of other components are not limited to, but include, for example, thickeners, moisturizers, pearlescent agents, anti-inflammatory agents, preservatives or bactericides such as phenoxyethanol, cooling agents, pH adjusters, fragrances, UV absorbers, antioxidants, chelating agents, film-forming polymer compounds, dyes, pigments, vitamins, amino acids, astringents, whitening agents, and plant and animal extracts.

[0041] The present invention also relates to an oil-in-water emulsion composition having a structure in which (a) 0.1 to 10% by mass of an acyl amino acid salt having an acyl group having 16 to 22 carbon atoms, (b) 1 to 50% by mass of an oil phase component, and (c) an aqueous phase component, wherein solid particles of (a) are adsorbed on the surface of oil droplets dispersed in the aqueous phase (also abbreviated as the oil-in-water emulsion composition of the present invention).

[0042] For example, the structure of the oil-in-water emulsion composition of the present invention using sodium N-stearoyl glutamate will be described in accordance with the manufacturing method described above. It is known from past literature that the Krafft point of sodium N-stearoyl glutamate is 60°C or higher (Oil Chemistry, Vol. 26, No. 12, p. 747, 1977). Therefore, in normal emulsification, sodium N-stearoyl glutamate is added to the aqueous phase, heated and dissolved, and then the oil phase, heated to the same degree, is added to the aqueous phase while stirring to emulsify. However, when returned to room temperature (around 25°C), the Krafft point of sodium N-stearoyl glutamate is high as described above, and it precipitates as a solid, thus reducing its emulsifying power. Therefore, in normal emulsification, a nonionic surfactant is often used as the main agent and N-stearoyl glutamate is often added as an auxiliary agent.

[0043] As described above, in the production method 1 of the present invention, first, N-stearoyl glutamate is dispersed and stirred in an oil phase to reduce the particle size. At this time, the temperature is in the range of room temperature, and heating is not particularly required. Then, when the aqueous phase is added, the fine particles of N-stearoyl glutamate dispersed in the oil phase aggregate on the surface of the oil droplets, thereby efficiently reducing the oil / water interfacial tension, and the emulsion particles are stabilized. By the production method 2 of the present invention in which the oil-in-water type emulsion composition obtained by the production method 1 of the present invention is further refined by a device such as a high-pressure emulsifier, a more stable oil-in-water type emulsion composition can be obtained.

[0044] The oil-in-water type emulsion composition of the present invention contains (a), (b) and (c), and the definitions and preferred ranges of each component are in accordance with the description. The mass ratio of component (a) to the total amount of the oil-in-water type emulsion composition is usually 0.1 to 10% by mass, preferably 0.2 to 8% by mass, more preferably 0.5 to 5% by mass. The mass ratio of component (b) to the total amount of the oil-in-water type emulsion composition is usually 1 to 50% by mass, preferably 3 to 45% by mass, more preferably 5 to 41% by mass. The mass ratio of component (c) to the total amount of the oil-in-water type emulsion composition is usually 30 to 97% by mass, preferably 40 to 95% by mass, more preferably 50 to 90% by mass.

[0045] In the oil-in-water type emulsion composition of the present invention, the mass ratio [(a):(b)] of (a) to (b) is usually 1:0.1 to 500, preferably 1:0.4 to 250, more preferably 1:1 to 82. In the oil-in-water type emulsion composition of the present invention, the mass ratio [(a):(c)] of (a) to (c) is usually 1:3 to 970, preferably 1:5 to 475, more preferably 1:10 to 180. In the oil-in-water type emulsion composition of the present invention, the mass ratio [(b):(c)] of (b) to (c) is usually 1:0.6 to 97, preferably 1:0.9 to 32, more preferably 1:1.2 to 18.

[0046] Also, as described above, the oil-in-water type emulsion composition of the present invention has a structure in which the solid particles of (a) are adsorbed on the surface of the oil droplets dispersed in the aqueous phase (c). By taking such a configuration, the emulsion composition is maintained stably and may have the form of a microemulsion.

[0047] The oil-in-water type emulsion composition of the present invention can be suitably provided as cleansing agents such as cleansing lotions, cleansing milks, and cleansing creams; external skin preparations in the form of emulsions, cream agents, etc.; skin cosmetics such as emulsions, creams, beauty essences, and lotions; base cosmetics such as base lotions and base creams; makeup cosmetics such as emulsion-type foundations and cream-type foundations; body cosmetics such as body lotions and body creams; sunscreen cosmetics such as sunscreen emulsions and sunscreen creams. When the oil-in-water type emulsion composition of the present invention has the form of a microemulsion, it is provided as a cosmetic having a normal liquid form. Specifically, it can be suitably provided as cleansing agents such as cleansing lotions and cleansing milks; external skin preparations in the form of emulsions, etc.; skin cosmetics such as emulsions, beauty essences, and lotions; base cosmetics such as base lotions; makeup cosmetics such as emulsion-type foundations; body cosmetics such as body lotions; sunscreen cosmetics such as sunscreen emulsions.

[0048] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited only to these examples. The content ratios in the tables are expressed in mass %, and "%" in the formulation examples means mass %.

[0049] Examples 1 to 13, Comparative Examples 1 to 9 Using each component described in Table 1, the manufacturing method (hereinafter abbreviated as the manufacturing process) was used to prepare each composition according to the method described below (the units in the table are mass %). The obtained compositions were evaluated by the method described below, and the results are shown in the table.

[0050] (Manufacturing Process) Manufacturing Process 1: After dissolving component (a) in the aqueous phase component (c) by heating at 80°C, the heated oil phase component (b) is added, stirred with a homomixer (2500 rpm, 1 minute), and then cooled. The microscopic photograph of the obtained composition was taken using a VH-X8000 manufactured by KEYENCE CORPORATION. The microscopic photograph is shown in Photograph 1 of FIG. 1.

[0051] Method 2: After dispersing component (a) in the oil phase component (b), it is micronized using a high-pressure emulsifier (100-200 MPa). Then, the aqueous phase component (c) is added and stirred, and further emulsified using a homomixer (2500 rpm, 1 minute) (corresponding to Method 1 of the present invention). Microscopic images of the obtained emulsified composition are similarly taken and shown in Figure 1, Photo 2. Figure 2 shows the particle size distribution of the emulsified composition measured using a particle size distribution analyzer LA-960V2 manufactured by Horiba, Ltd.

[0052] Method 3: The oil-in-water emulsion composition obtained in Method 2 is further micronized using a high-pressure emulsifier (100 MPa or higher) (corresponding to Method 2 of the present invention). Microscopic images of the obtained emulsion composition are similarly taken and shown in Figure 1, Photo 3. The particle size distribution of the emulsion composition measured using a particle size distribution analyzer LA-960V2 manufactured by Horiba, Ltd. is shown in Figure 2.

[0053] (Evaluation) The oil-in-water emulsion compositions obtained in the examples and comparative examples were evaluated as follows. The evaluation results are shown in the table.

[0054] [Emulsification Stability] 50 ml of the obtained oil-in-water emulsion composition was placed in a screw-cap tube (transparent) and stored at 25°C for one week. A score of ○ was given if no separation or precipitation occurred, a score of △ if slight separation or precipitation occurred, and a score of × if separation or precipitation was clearly observed. A score of ◎ was given if the product was stable for more than one month.

[0055] [User Experience] The obtained oil-in-water emulsion composition was evaluated by five monitors. Approximately 0.1 ml was applied to the inner side of the forearm, and it was evaluated on a scale of 3 points if no stickiness was felt, 2 points if it felt slightly sticky, and 1 point if it felt sticky. If the average score of the five monitors was 2 points or higher, it was marked with ○, if it was between 1 point and 2 points, it was marked with △, and if it was 1 point or less, it was marked with ×.

[0056] [Skin Irritation (Sensitivity)] The obtained oil-in-water emulsion was evaluated by five monitors. Approximately 0.1 ml was applied to the inner side of the forearm, and the evaluation was given on a scale of 3 points for no irritation, 2 points for slight irritation, and 1 point for irritation. A score of 2 points or higher was marked with ○, a score between 1 and 2 points was marked with △, and a score of 1 point or less was marked with ×.

[0057]

[0058]

[0059]

[0060]

[0061] Furthermore, examples of formulations of the oil-in-water emulsion composition of the present invention are shown below. The composition was prepared by either Method 2 or Method 3, which are within the scope of the present invention. The emulsion stability, usability, and skin irritation of these compositions were good.

[0062] Formula Example 1 Cleansing Lotion (Manufacturing Method 2) Ingredients (a) Sodium N-stearoyl glutamate 5.0% Ingredients (b) Phytosteryl / octyldodecyl lauroyl glutamate 5.0% Liquid paraffin 30.0% Isopropyl myristate 5.0% Beeswax 0.2% Olive oil 0.2% Ingredients (c) Glycerin 10.0% Phenoxyethanol 0.2% Fragrance 0.2% Purified water residue

[0063] Formula Example 2: Beauty Serum Cream (Manufacturing Method 2) Ingredients (a) Sodium N-stearoyl glutamate 3.0% Ingredients (b) Sunflower oil 20.0% Petrolatum 5.0% Phytosteryl / octyldodecyl lauroyl glutamate 5.0% Ingredients (c) Glycerin 10.0% Butylene glycol 3.0% Sodium hyaluronate 0.1% N-Coconut oil fatty acid acyl-L-arginine ethyl / DL-pyrrolidone carboxylate 0.1% Phenoxyethanol 0.2% Fragrance 0.2% Purified water residue

[0064] Formula Example 3 Cleansing Lotion (Manufacturing Method 3) Ingredients (a) Sodium N-stearoyl glutamate 1.5% Ingredients (b) Phytosteryl / octyldodecyl lauroyl glutamate 7.0% Polyglyceryl laurate 2.0% Squalane 5.0% Dimethylpolysiloxane 10cp 2.0% Avocado oil 0.2% Ingredients (c) Glycerin 5.0% Hydrogenated lecithin 0.5% Phenoxyethanol 0.2% Fragrance 0.2% Purified water residue

[0065] Formula Example 4: Beauty Serum Lotion (Manufacturing Method 3) Ingredients (a) Sodium N-stearoyl glutamate 2.0% Ingredients (b) Phytosteryl / octyldodecyl lauroyl glutamate 5.0% Olive oil 10.0% Octyldodecyl myristate 10.0% Natural vitamin E 0.1% Ingredients (c) Glycerin 5.0% Dipotassium glycyrrhizate 0.1% Ascorbic acid 2-glucoside 2.0% Glycine 0.1% Alanine 0.1% Serine 0.1% Arginine 0.1% Glutamic acid 0.1% Phenoxyethanol 0.2% Fragrance 0.2% Purified water residue

[0066] The present invention provides a fine oil-in-water emulsion composition containing an acyl amino acid salt having an acyl group with 16 to 22 carbon atoms, exhibiting excellent emulsification stability and usability. The oil-in-water emulsion composition of the present invention is useful as an emulsified cosmetic. The present invention also allows for the production of an even finer oil-in-water emulsion composition without a heating process.

[0067] This application is based on Japanese Patent Application No. 2024-186850, the contents of which are fully incorporated herein.

Claims

1. A method for producing an oil-in-water emulsion composition, comprising the steps of: (1) stirring (a) 0.1 to 10% by mass of an acyl amino acid salt having acyl groups with 16 to 22 carbon atoms and (b) 1 to 50% by mass of an oil phase component to disperse (a) in (b); and (2) adding (c) an aqueous phase component to the obtained mixture and stirring.

2. The manufacturing method according to claim 1, further comprising (3) a step of high-pressure emulsification.

3. The production method according to claim 1, wherein the acyl amino acid salt having an acyl group with 16 to 22 carbon atoms is N-stearoyl glutamate.

4. (b) The method for producing the product according to claim 1, wherein the oil phase component comprises N-lauroyl-L-glutamic acid di(phytosteryl / 2-octyldodecyl).

5. The manufacturing method according to claim 1, wherein the average particle size of the emulsion particles of the oil-in-water emulsion composition is 1 to 500 μm.

6. The manufacturing method according to claim 2, wherein the average particle size of the emulsion particles of the oil-in-water emulsion composition is 50 to 500 nm.

7. The method for producing the oil-in-water emulsion composition according to claims 2 to 6, wherein the oil-in-water emulsion composition is a microemulsion.

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