O / d phase compositions and oil-in-water emulsions

Abstract

This invention relates to O / D phase compositions and oil-in-water emulsion compositions. O / D phase compositions can be used to prepare oil-in-water emulsion compositions using a general-purpose stirring mixer. Even after dilution, the dispersion of fine emulsion particles remains stable, resulting in oil-in-water emulsion compositions with low skin irritation. An oily component is added to a surfactant (cleanser) phase component obtained by dissolving one or more of glycyrrhizic acid and its salts in a polyol with three or more nucleotides, to prepare an O / D phase composition with the pH adjusted to 5.0 or below in a 10% by mass aqueous solution. This is then used to prepare an oil-in-water emulsion composition with a particle size (median particle size) of less than 1.0 μm using a stirring mixer such as a homogenizer.

Description

Technical Field

[0001] This invention relates to O / D phase compositions for preparing oil-in-water emulsions such as cosmetics, and to oil-in-water emulsion compositions prepared from the O / D phase compositions. Background Technology

[0002] In emulsified compositions widely used in cosmetics such as creams and lotions, surfactants are used to evenly disperse water and oil. It is known that such surfactants are prone to becoming irritants, especially when the skin is highly sensitive to various stimuli, i.e., when it is known as sensitive skin.

[0003] Incidentally, when developing topical agents for sensitive skin that is prone to symptoms such as itching, skin inflammation, irritation, acne, photosensitivity, and stinging, it is necessary to avoid using preservatives, surfactants, stabilizers, antioxidants, UV absorbers, etc., which may irritate the skin, or to use only the minimum amount, or to use alternative ingredients to maintain the desired properties.

[0004] For example, nonionic surfactants are preferred over ionic surfactants as they are less irritating to the skin. Not only for people with sensitive skin, but also for healthy individuals, cosmetics with fewer irritating ingredients are preferred; therefore, it is preferable to formulate cosmetics and other topical skin agents with as few surfactants as possible.

[0005] However, the particle size of emulsified particles in emulsion compositions used in cosmetics has become an important factor in the stability of the emulsion state, the feel of the cosmetic, and its effectiveness. Research is underway to further reduce the particle size through appropriate ingredients and preparation processes, thereby improving skin adaptability and permeability.

[0006] To prepare it into fine particles, a high-pressure emulsifier, also known as a pressure homogenizer, is used. This allows for micronization by mechanical force, for example, when the emulsion particles are pressurized to 10–100 MPa and passed through a homogenization valve in the device, the emulsion particles are crushed and dispersed by shearing action caused by collisions, thus becoming fine emulsion particles.

[0007] When using such a high-pressure emulsifier, a surfactant is also necessary. It is known to use a surfactant with low skin irritation, namely a polymer with phosphorylcholine groups, to manufacture O / W type emulsions with an average droplet size of 10 to 3000 nm (Patent Document 1, paragraph

[0033] ).

[0008] In emulsification methods that incorporate surface-active components and generate fine emulsion particles using mechanical force, specialized equipment such as high-pressure emulsifiers are required. It is difficult to manufacture such products using general-purpose manufacturing equipment such as homogenizers that do not have a pressurizing mechanism.

[0009] Furthermore, the "D-phase emulsification method" is well-known as an emulsification method that does not require significant mechanical force. The D-phase emulsification method involves dissolving a surfactant in a polyol such as glycerol, and then slowly adding an oil phase (O phase) under stirring conditions to obtain an O / D phase (Oil / Detergent-Phase). This phase is then further diluted with water or the like, thereby preparing an oil-in-water emulsion.

[0010] If such an emulsification method is used, emulsification can be performed using a general-purpose mixer such as a homogenizer. However, in the method described in Patent Document 2, when performing the D-phase emulsification method, it is necessary to add 0.01 to 10% by mass of an oily component with a melting point of 70°C or higher, and the D-phase needs to be emulsified at a high temperature of 70°C or higher. In addition, polyglycerol fatty acid esters are required as surfactants, and glycyrrhizic acid salts are not used.

[0011] In addition, there is a known method for obtaining an emulsion for skin cosmetics by using glycyrrhizic acid, which is an ingredient not classified as a surfactant but is expected to have stable surface-active effects, for D-phase emulsification (Patent Document 3).

[0012] In addition, the glycyrrhizic acid or its salts mentioned above have three carboxyl groups in their molecules. Therefore, based on the higher the degree of neutralization of the alkali, the higher the solubility in water, the pH is usually adjusted to be above 5.0.

[0013] Existing technical documents

[0014] Patent documents

[0015] Patent Document 1: Japanese Patent No. 3975895

[0016] Patent Document 2: Japanese Patent No. 6386738

[0017] Patent Document 3: Japanese Patent Application Publication No. 2006-124319 Summary of the Invention

[0018] However, regarding the emulsification method described in Patent Document 3, although the combination of D-phase emulsification and homogenization with glycyrrhizic acid can produce an emulsion with an average particle size of 2.0 to 5.0 μm, it is impossible to prepare a fine average particle size of less than 1.0 μm. In order to achieve such preparation, it is necessary to further use a microfluidizer to perform high-pressure emulsification on the above emulsion (Patent Document 3,

[0057] to

[0059] ).

[0019] That is, in conventional emulsification methods that combine D-phase emulsification using glycyrrhizic acid with homogenization, emulsions with tiny submicron particle sizes of less than 1.0 μm with an average particle size were not obtained.

[0020] Furthermore, in the emulsification method of the aforementioned Patent Document 3, the proportion of the oily component in the oil-in-water emulsion composition needs to be limited to less than 60% by mass, thus failing to obtain a versatile oil-in-water emulsion composition for use in cosmetics.

[0021] Therefore, the objective of this invention is to solve the aforementioned problems by using glycyrrhizic acid O / D phase compositions that do not require special manufacturing equipment with a pressurizing mechanism, such as a high-pressure emulsifier. Instead, a general-purpose mixing machine, such as a homogenizer, can be used to prepare oil-in-water emulsion compositions. Even when diluted, the dispersion of the fine emulsion particles remains stable, resulting in oil-in-water emulsion compositions that are less irritating to the skin.

[0022] The inventors of this application conducted repeated and in-depth research and discovered that, regarding an O / D phase composition containing glycyrrhizic acid or its salts or both, a polyol with three or more components, and an oily component, by adjusting the pH of its 10% by mass aqueous solution to below 5.0, even without using a high-pressure emulsifier, a submicron emulsion with a particle size (median particle size) of less than 1.0 μm can be obtained, thus completing this invention.

[0023] In order to solve the above-mentioned problems, the present invention provides an O / D phase composition comprising an oily component added to a D (detergent) phase component, wherein the D (detergent) phase component contains one or more polyols selected from glycyrrhizic acid and its salts and having three or more tertiary components, and wherein a 10% by mass aqueous solution of the O / D phase composition has a pH of 5.0 or less.

[0024] The O / D phase composition of the present invention, as described above, consists of a D (detergent) phase and an oil phase with the specified components. The pH of its 10% by mass aqueous solution is adjusted to below 5.0. Therefore, the energy required for the generation of emulsion particles is relatively small, and the emulsion particles are easily dispersed in water, allowing for emulsification using a general-purpose stirred mixer. In particular, if a general-purpose stirred mixer such as a homogenizer is used, an oil-in-water emulsion composition with a particle size (median particle size) of less than 1.0 μm can be obtained.

[0025] When using such an O / D phase composition and emulsifying it using a general-purpose mixer without a special pressurization mechanism, such as a homogenizer, it is possible to incorporate more than 30% by mass of oily components into the O / D phase composition, and further, more than 60% by mass, for example, more than 60% by mass but 65% by mass, or 60 to 70% by mass.

[0026] The resulting oil-in-water emulsion composition is an emulsion in which emulsion particles are stably dispersed. Furthermore, by using glycyrrhizic acid or its salts as surfactants, it is less irritating to those with sensitive skin and can also be expected to have anti-inflammatory effects.

[0027] This invention uses one or more compounds selected from glycyrrhizic acid and its salts and three or more polyols to form an O / D phase composition adjusted to a specified pH range. Therefore, when emulsifying by dilution with aqueous components, no special manufacturing equipment such as a high-pressure emulsifier is required, and it has the advantage of being able to be emulsified easily using a general-purpose mixing machine.

[0028] In addition, the D-phase oil-in-water emulsion particles formed by the O / D phase composition are in a stable micro-dispersion state, resulting in submicron-sized emulsion particles with a median particle size of less than 1.0 μm dispersed in aqueous components. This allows for the efficient exertion of the anti-inflammatory effects of glycyrrhizic acid or its salts. Therefore, it also has the advantages of being less irritating to the skin and being a versatile oil-in-water emulsion composition suitable for cosmetics and the like. Detailed Implementation

[0029] The oil-in-water emulsion composition of the present invention comprises a composition in which an oily component is added to the D (detergent) phase component. The D (detergent) phase component includes one or more compounds selected from glycyrrhizic acid and its salts and three or more polyols. The oil-in-water emulsion composition is formed by dispersing oil-in-water emulsion particles of the D phase formed by the O / D phase composition within a specified pH range on the acidic side in the aqueous component.

[0030] That is, the pH of the 10% by mass aqueous solution of the above O / D phase composition is adjusted to below 5.0, so it is easy to form emulsion particles, that is, the energy consumption for emulsification is small, so an oil-in-water emulsion composition can be prepared using a stirring mixer without a pressure mechanism.

[0031] The glycyrrhizic acid or its salts used in this invention are components that, in addition to their surface-active effects, can also be expected to have anti-inflammatory effects in cosmetics, quasi-drugs, pharmaceuticals, etc. They are natural organic compounds that are biosynthesized in plants and are abundant in licorice, in particular.

[0032] Examples of glycyrrhizic acid salts include monopotassium glycyrrhizate, dipotassium glycyrrhizate, disodium glycyrrhizate, trisodium glycyrrhizate, and ammonium glycyrrhizate, but these are not limited to.

[0033] Furthermore, glycyrrhizic acid or its salts can be used as one or more surfactant compounds. Additionally, plant extracts containing glycyrrhizic acid or its salts, such as licorice root extract, can be used, with dipotassium glycyrrhizate or ammonium glycyrrhizate being preferred.

[0034] The proportion of glycyrrhizic acid or its salts is not particularly limited, but it is preferred to be added to the O / D phase composition at 0.1% to 6% by mass, more preferably 0.5% to 4% by mass, in a manner that achieves the desired emulsifying properties. If the amount added is less than 0.1% by mass, it is not easy to prepare the O / D phase composition, and if it is more than 6% by mass, dissolution in polyols becomes quite difficult, so it is not preferred.

[0035] The O / D phase (Oil / Detergent-Phase) composition of the present invention is obtained by dissolving a surface-active component such as glycyrrhizic acid in a polyol with three or more nucleotides, such as glycerol, and slowly adding the oil phase component under stirring conditions, thereby dispersing the oil phase in the D phase, thus obtaining an oil-in-D phase emulsion composition. If it is diluted with an aqueous component such as water to disperse the emulsion particles in the aqueous component, a water-in-oil emulsion composition is obtained. The D phase component may contain water.

[0036] If the pH of a 10% by mass aqueous solution of the O / D phase composition is below 5.0, no pH adjuster is required. Organic acids, inorganic acids, vitamins, amino acids, etc. can be used as pH adjusters as needed to adjust the pH to below 5.0 (or pH below 5.0).

[0037] For example, it is preferable to incorporate citric acid, phosphoric acid, malic acid, lactic acid, glycolic acid, ascorbic acid, glutamic acid, aspartic acid, acetic acid, tartaric acid, etc., into the O / D phase composition, with citric acid, phosphoric acid, malic acid, and lactic acid being more preferred. There are no particular limitations on the incorporation of these substances, and they can be dissolved in water before incorporation. The water used in the incorporation is preferably in the O / D phase composition at 0.5% to 5% by mass, more preferably 1% to 4% by mass.

[0038] In the case of polyols with three or more nucleotides used in this invention, the number of hydroxyl groups present in the molecule is taken as the nucleotide number, for example, polyols with three or more nucleotides such as glycerol are used.

[0039] The polyols with three or more nucleotides that can be used in this invention include, but are not limited to, water-soluble polyols with three or more nucleotides. Furthermore, one type of polyol can be used, or a combination of two or more can be used. Preferably, glycerol, diglycerol, polyglycerol, sorbitol, maltitol, glycerol glucoside, etc., which are sugars, are used; glycerol, maltitol, and glycerol glucoside are more preferred.

[0040] The oily components used in this invention are not particularly limited, and examples include animal and vegetable oils, waxes, hydrocarbon oils, fatty acids, higher alcohols, ester oils, triglycerides, silicone oils, etc. These can be used alone, or in combination of two or more.

[0041] Examples of oily components include plant oils such as macadamia nut oil, corn oil, rapeseed oil, sunflower seed oil, castor oil, olive oil, cocoa butter, camellia oil, coconut oil, wood wax, jojoba oil, grapeseed oil, avocado oil, rice bran oil, evening primrose oil, soybean oil, cottonseed oil, sesame oil, safflower seed oil, palm oil, flaxseed oil, perilla oil, shea butter, meadowfoam seed oil, and salsa oil; animal oils such as horse oil, wild boar oil, emu oil, deer fat, mink oil, and egg yolk oil; waxes such as beeswax, whale wax, lanolin, carnauba wax, and candelilla wax; hydrocarbon oils such as liquid paraffin, squalene, microcrystalline wax, ceresin, paraffin wax, and petrolatum; and natural and synthetic lipids such as lauric acid, myristic acid, palmitic acid, stearic acid, benzyl acid, isostearic acid, oleic acid, linolenic acid, and hydroxystearic acid. Fatty acids, including natural and synthetic higher alcohols such as cetyl alcohol, stearyl alcohol, hexyldecyl alcohol, octyldecyl alcohol, lauryl alcohol, cholesterol, and phytosterols; esters such as isopropyl myristate, isopropyl palmitate, isopropyl stearate, octyldodecyl myristate, octyldodecyl oleate, glyceryl 2-ethylhexanoate, and cholesterol oleate; triglycerides such as caprylic / capric triglycerides, 2-ethylhexanoate triglycerides, caprylic / capric / myristic / stearic triglycerides, and triisostearate; and organosilicones such as dimethyl polysiloxane, highly polymerized dimethyl polysiloxane, amino-modified organosilicon, polydimethylsiloxane alcohol, polyether-modified organosilicon, polyglycerol-modified organosilicon, methylphenyl organosilicon, betaine-modified organosilicon, alkyl-modified organosilicon, alkoxy-modified organosilicon, and cyclic organosilicon.

[0042] Regarding the particle size (median particle size) of the emulsion particles dispersed in water, there is no particular need to limit it as long as the emulsion state is stable. However, emulsion particles with a size of 5.0 μm or larger tend to cause instability such as emulsion separation or aggregation. Therefore, it is preferable to have a smaller particle size (median particle size) than that, and more preferably a particle size (median particle size) of less than 1.0 μm.

[0043] Furthermore, the water-in-oil emulsion composition of the present invention can be appropriately supplemented with various additives commonly used in cosmetics in a manner that does not impair the effects of the present invention.

[0044] Examples of such additives include moisturizers, metal chelators, sugars, amino acids, vitamins, antioxidants, pigments, fragrances, plant extracts, hormones, and skin-whitening ingredients.

[0045] Examples of humectants include ethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, dipropylene glycol, pentanediol, hexanediol, propanediol, and methylpropanediol.

[0046] Examples of metal chelating agents include ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediamineacetic acid, phytic acid, nitrotriacetic acid, and their salts.

[0047] Examples of sugars include glucose, sucrose, fructose, xylitol, maltotriose, threitol, and erythritol.

[0048] Examples of amino acids include taurine, glutamic acid, glycine, lysine, histidine, serine, valine, aspartic acid, threonine, alanine, isoleucine, phenylalanine, arginine, proline, tyrosine, inosinic acid, guanylic acid, PCA, and glycine.

[0049] Examples of vitamins include retinol, riboflavin, pyridoxine, ascorbic acid, tocopherol, hesperidin, pantothenic acid, cyanocobalamin, biotin, and their derivatives.

[0050] Examples of antioxidants include butylated hydroxytoluene, butylated hydroxyanisole, propyl gallate, and tocopherol.

[0051] As pigments, examples include tar pigments listed in the legal pigments list, gardenia extract, chili extract, bell pepper extract, Monascus purpureus extract, cocoa extract, sea buckthorn fruit oil, charcoal, carmine, Phellodendron bark extract, Scutellaria baicalensis extract, caramel and other plant and animal-derived components, as well as pigment components such as iron oxide, titanium dioxide, kaolin, and barium oxide.

[0052] Examples of hormones include estradiol, estrone, ethinylestradiol, cortisone, hydrocortisone, and prednisone.

[0053] As skin-whitening ingredients, examples include ascorbic acid, arbutin, ellagic acid, tranexamic acid, hydroquinone, placental extract, chamomile extract, kojic acid, linoleic acid and their derivatives.

[0054] Example

[0055] The O / D phase compositions of the examples and comparative examples were prepared by dissolving polyols with three or more components and glycyrrhizic acid or its salts in the proportions shown in Tables 1-4 below, while gradually adding the oily components over about 20 minutes, and stirring at 500-1000 rpm to prepare 1 kg of O / D phase composition.

[0056] The mixer used was a MAZELA ZZ-1100 mixer manufactured by Tokyo Rika Kiki Co., Ltd. Depending on the amount and type of oily components and polyols with three or more components, the viscosity of the O / D phase composition was reduced by heating when it was difficult to stir due to its high viscosity.

[0057] The O / D phase composition was homogenized using a homogenizer at 3000–5000 rpm to refine the oil-in-water emulsion particles in the D phase. Then, it was diluted with the remaining water-soluble solvent to prepare an oil-in-water emulsion composition. The homogenizer used was a Primix HOMOGENIZING MIXER MARKII.

[0058] (Evaluation method: visual inspection)

[0059] Prepare O / D phase compositions (O / D gels), visually observe the appearance of the gels, and evaluate them according to the following criteria. The judgment results are indicated by symbols in the table.

[0060] [Evaluation] [Judgment]

[0061] Uniform gel: ○

[0062] Oil floats or separates: ×

[0063] (Evaluation method: Appearance upon dilution)

[0064] The appearance of the emulsion obtained by diluting the O / D phase composition with purified water to 10% by mass was visually observed and evaluated according to the following criteria. The judgment results are indicated by symbols in the table.

[0065] [Evaluation] [Judgment]

[0066] A uniform emulsion: ○

[0067] Oil floats or separates: ×

[0068] (Evaluation method: Emulsion particle size (μm))

[0069] The median particle size of the emulsion was determined using a laser diffraction particle size distribution measuring device: a MASTERSIZER3000 manufactured by Malvern.

[0070] (Evaluation method: pH)

[0071] The pH of the emulsion obtained by diluting the O / D phase composition to 10% by mass with purified water was determined.

[0072] [Table 1]

[0073]

[0074] As can be clearly seen from the results shown in Table 1, in Comparative Example 1, when the pH was adjusted to acidity using citric acid and exceeded 5.0, the separation of the O / D phase composition was confirmed.

[0075] On the other hand, in Examples 1-4, by adjusting the pH to below 5.0, the appearance and dilution state were confirmed to be stable, and the particle size (median particle size) was also reduced to less than 1.0 μm. The pH of the emulsions of the O / D phase compositions of Examples 1-4 diluted to 10% by mass was below 5.0.

[0076] [Table 2]

[0077]

[0078] As can be clearly seen from the results shown in Table 2, in Examples 5-9, malic acid, phosphoric acid, and lactic acid, other than citric acid, were used to adjust the pH, and all achieved the same effect as citric acid.

[0079] In addition, in Comparative Examples 2 and 3, the pH was made above 5.0 by adding potassium hydroxide or arginine, so oil was observed to float or separate, and an O / D phase composition consisting of a uniform gel was not obtained.

[0080] [Table 3]

[0081]

[0082] As can be clearly seen from the results shown in Table 3, in Examples 10-12, the polyols with three or more components used glycerol glucoside other than glycerol and maltitol, all of which formed O / D phase compositions.

[0083] In addition, in Examples 12 and 16, the oily components used were sunflower seed oil and tricaprylic acid glyceride, which are vegetable oils with higher polarity than octyl palmitate, and can be identified as O / D phase compositions.

[0084] Furthermore, based on the results of Examples 12-15, the formation of the O / D phase composition was confirmed even though there were no restrictions on the amount of polyols with three or more components and the amount of oil.

[0085] However, in Comparative Example 4, which used 1,3-butanediol as a binary polyol, no O / D phase composition was formed. Furthermore, in Comparative Example 5, which did not contain a polyol, an O / D phase composition was similarly not formed, as in Comparative Example 4.

[0086] The oil-in-water emulsion compositions of Examples 17-19 were prepared using the O / D phase composition of Example 11 according to the proportions shown in Table 4 below. The components other than those of Example 11 were mixed in purified water and heated and stirred at 70-85°C for 15 minutes to dissolve them. After cooling, the composition of Example 11 was added and stirred to form the final formulation. A MAZELA ZZ-1100 mixer manufactured by Tokyo Rika & Machinery Co., Ltd. was used as the mixer.

[0087] [Table 4]

[0088]

[0089] As can be seen from the results shown in Table 4, in Example 17, an emulsion was prepared using the O / D phase composition of Example 11 described above, and in Examples 18 and 19, creams were prepared.

[0090] The resulting oil-in-water emulsion composition has a submicron particle size (median particle size) (less than 1.0 μm), and as a formulation, the emulsion particles exhibit stable dispersion.

Claims

1. An O / D phase composition comprising a composition in which an oily component is added to the D phase (detergent phase), wherein the D phase comprises one or more polyols selected from glycyrrhizic acid and its salts, and having three or more nucleotides. The pH of a 10% by mass aqueous solution of the O / D phase composition is 4.0–5.

0. The polyols with three or more components are selected from one or more of glycerol, polyglycerol, sorbitol, maltitol, and glycerol glucoside. One or more of the glycyrrhizic acid and its salts are incorporated in the O / D phase composition at a concentration of 0.1% to 6% by mass.

2. The O / D phase composition according to claim 1, wherein, The polyglycerol is diglycerol.

3. The O / D phase composition according to claim 1, wherein, The salts of glycyrrhizic acid are dipotassium glycyrrhizate or ammonium glycyrrhizate.

4. The O / D phase composition according to any one of claims 1 to 3, wherein, The D phase, i.e., the cleaning agent phase, contains water.

5. An oil-in-water emulsion composition is formed by dispersing the D-phase oil-in-water emulsion particles formed by the O / D phase composition according to any one of claims 1 to 3 in an aqueous component.

6. The oil-in-water emulsion composition according to claim 5, wherein, The median particle size of the emulsified particles in the oil-in-water emulsion composition is less than 1.0 μm.

7. An oil-in-water emulsion composition is formed by dispersing the D-phase oil-in-water emulsion particles formed by the O / D phase composition of claim 4 in an aqueous component.

8. The oil-in-water emulsion composition according to claim 7, wherein, The median particle size of the emulsified particles in the oil-in-water emulsion composition is less than 1.0 μm.

Images