JP7730148B2 - Oil gel particles and topical skin composition containing the same - Google Patents

Description

The present invention relates to oil gel particles that contain an oil agent and have a transparent appearance, and to topical skin compositions containing the same.

Oil-based particles and microcapsules that are large enough to be seen with the naked eye and can be incorporated into external compositions such as cosmetics are known.

For example, Patent Document 1 describes oil particles containing a dextrin fatty acid ester and a liquid oil, which are obtained by incorporating 5 to 40% by mass of the dextrin fatty acid ester relative to the total mass of the oil particles, and which have an average particle size of 0.05 to 10 mm. Patent Document 2 also describes oil particles produced by incorporating 5 to 40% by mass of an amphiphilic substance with a melting point of 45 to 75°C, containing batyl alcohol and/or glyceryl stearate, relative to the total mass of the oil particles, and discloses that the stability of the vitamin A fatty acid ester contained in these oil particles is improved. Patent Document 3 also describes a method for producing such oil particles, in which oil, which is kept in a liquid state at a temperature above its melting point, is added to an aqueous solvent being stirred at a temperature of 55 to 75°C, and the specific gravity of the oil relative to the aqueous solvent is 0.90 to 2.3. The aqueous solvent is then cooled to a temperature below the melting point of the oil while still stirring, to form oil particles in the aqueous solvent.

Japanese Patent Application Laid-Open No. 2005-36001 Patent No. 4330511 Patent No. 4189921

However, the oily particles described in Patent Document 1 are intended to be granulated within a cosmetic formulation, and if an attempt is made to sift the granulated oily particles alone for use in other applications, the particles will be crushed on the sieve, making it unlikely that the particles will be obtained alone. The oily particles described in Patent Document 2 contain a high concentration of batyl alcohol and/or glyceryl stearate, which have high water affinity and crystallinity, as a coating for the oily particles, and it is believed that the appearance of the particles becomes cloudy due to emulsification during granulation and crystal precipitation after cooling. The oily particles described in Patent Document 3, like those described in Patent Document 2, also contain a high concentration of behenyl alcohol, which has high water affinity and crystallinity, as a particle solidifying component, and it is believed that the appearance of the particles becomes cloudy.

On the other hand, if the amount of gelling agent or solid oil is increased excessively in order to sieve the oily particles, the particles will be too hard and will feel unpleasant when applied to the skin. Furthermore, if an emulsifier or a component with high affinity for water is added to the particles, it is thought that there is an advantage in that the particles will blend with water and be easier to crush when blended into water-based cosmetics such as lotions.

The problem that the present invention aims to solve is to provide oil gel particles that have a highly transparent appearance in the atmosphere, are strong enough to be sieved, and have the moist feel characteristic of oily agents when applied to the skin, as well as cosmetics containing the oil gel particles.

The present invention has been made to solve the above-mentioned problems, and provides, for example, oil gel particles in which the type and content of the oil agent and gelling agent used in the oil gel particles are optimized, and the balance between the organic and inorganic values of the oil agent is adjusted.

That is, the present invention includes the following embodiments.
[1] Oil gel particles containing 50 to 99% by mass of an oil agent and 0.5 to 50% by mass of a gelling agent, wherein the IOB value of the oil agent is 0.85 or less.
[2] Oil gel particles according to [1], further comprising 0.5 to 10 mass% of a surfactant, wherein the combined HLB value of the oil agent and the surfactant is 8.5 or less.
[3] The oil gel particles according to [1] or [2], having an average particle size of 100 to 2000 μm.
[4] Oil gel particles according to any one of [1] to [3], wherein the oil agent is at least one selected from the group consisting of hydrocarbon oils, ester oils, silicone oils, and vegetable oils.
[5] Oil gel particles according to any one of [1] to [4], wherein the gelling agent is a dextrin fatty acid ester, an inulin fatty acid ester, and/or an amino acid-based oil gelling agent.
[6] A composition for external use on skin, comprising the oil gel particles according to any one of [1] to [5] in a dispersed state in an aqueous medium or an oily medium.

The present invention makes it possible to provide oil gel particles and the like that have a highly transparent appearance and, when applied to the skin, have the moist feel characteristic of oily agents.

The outline of the evaluation of dispersibility (absorbance test) described in Examples 35 to 40 is shown below.

Next, we will explain each embodiment of the present invention. Please note that the embodiments described below do not limit the invention as defined in the claims, and not all of the elements and combinations thereof described in each embodiment are necessarily essential to the solution of the present invention.

(oil gel particles)
An oil gel particle according to one embodiment of the present invention comprises (A) 50 to 99% by mass of an oil agent and (B) 0.5 to 50% by mass of a gelling agent. Here, "oil gel particle" refers to one or more particles in which a desired component is dissolved or dispersed in an oil agent. Furthermore, in this specification, "oil gel" refers to a gel-like oil agent (oil-based component) thickened with a lipophilic gelling agent, and can be prepared, for example, by adding an oil-based gelling agent to an oil agent.

The shape of the oil gel particles is not particularly limited, but from the standpoint of shape stability and aesthetics, a spherical shape is preferred. Here, "spherical" refers not only to a perfect sphere but also to an elliptical cross section, with a perfect sphere being preferred. Furthermore, the average particle size of the oil gel particles of this embodiment is preferably 100 μm or more, more preferably 125 μm or more, even more preferably 150 μm or more, and even more preferably 175 μm or more, for example, to facilitate the production of spherical particles or to allow for visual observation of the particles. Furthermore, the upper limit of the average particle size is 2000 μm or less, preferably 1500 μm or less, and more preferably 1000 μm or less, to prevent the particles from becoming too hard. The average particle size of the oil gel particles can be measured by laser diffraction/scattering or sieving. The laser diffraction/scattering method involves measuring the median diameter using a particle size distribution analyzer (e.g., Horiba, Ltd., Model No. LA-920) and using this as the average particle size. The sieve method involves wet classifying 100 g of oil gel particles in water using sieves with various mesh sizes, removing excess water with filter paper, measuring the mass, and using the weight-average particle size as the average particle size.

Furthermore, from the viewpoint of improving the feel during use, the compressive breaking strength of the oil gel particles of this embodiment is preferably 50 kPa or less. From the viewpoint of maintaining the shape of the oil gel particles and making them easier to incorporate into topical skin preparations, cosmetics, etc., the compressive breaking strength of the oil gel particles of this embodiment is preferably 0.15 kPa or more, more preferably 0.20 kPa or more, and even more preferably 0.25 kPa or more. Furthermore, from the viewpoint of achieving good spreadability and compatibility on the skin when applied to the skin and enabling smooth disintegration, the compressive breaking strength of the oil gel particles of this embodiment is more preferably 40 kPa or less, and even more preferably 30 kPa or less.

Here, the compressive breaking strength refers to the maximum stress at which a gel sample breaks when a compressive load is applied to the gel sample. The compressive breaking strength can be expressed as the value (kPa (N/m ² )) obtained by dividing the compressive force when a uniaxial load is applied to a spherical gel sample by the cross-sectional area perpendicular to that axis. The compressive breaking strength is also called the compressive breaking stress, and can be measured by a known method using a known measuring device. An example of a compressive breaking strength measuring device is a compression testing machine (Rheo Meter: CR-3000EX) manufactured by Sun Scientific Co., Ltd. The compressive breaking strength specified in this embodiment is a value measured by the measurement method described in the examples shown below.

The oil gel particles of this embodiment can encapsulate desired components and may also contain optional components as long as they do not impair the effects of the present invention. The ingredients and their contents of the oil gel particles of this embodiment are described in detail below.

(oil agent)
The oil agent of component (A) used in the oil gel particles of this embodiment can be a liquid oil used in external compositions such as cosmetics.Specifically, for example, liquid oils derived from animals or plants can be used, such as linseed oil, camellia oil, macadamia nut oil, corn oil, olive oil, avocado oil, camellia oil, castor oil, safflower oil, apricot kernel oil, cinnamon oil, jojoba oil, grape oil, sunflower oil, almond oil, rapeseed oil, sesame oil, wheat germ oil, rice germ oil, rice bran oil, cottonseed oil, soybean oil, peanut oil, tea seed oil, evening primrose oil, egg yolk oil, and cod liver oil.The liquid oils can be synthetic or commercially available. Examples of commercially available products include DHA-55 (manufactured by Maruha Nichiro Co., Ltd.), safflower oil (manufactured by Nisshin Oillio Co., Ltd.), Oryza salad oil (manufactured by Oryza Oil & Fat Chemical Co., Ltd.), edible olive oil (manufactured by J-Oil Mills Co., Ltd.), linseed oil S (manufactured by Nippon Flour Mills Co., Ltd.), and Coconard ML (manufactured by Kao Corporation).

Ester oils such as octanoic acid esters such as cetyl octanoate, isooctanoic acid esters such as glycerin tri-2-ethylhexaenoate and pentaerythritol tetra-2-ethylhexanoate, lauric acid esters such as hexyl laurate, myristates such as isopropyl myristate and octyldodecyl myristate, palmitic acid esters such as octyl palmitate, stearic acid esters such as isocetyl stearate, isostearic acid esters such as isopropyl isostearate, isopalmitic acid esters such as octyl isopalmitate, oleic acid esters such as isodecyl oleate, adipic acid diesters such as diisopropyl adipate, sebacate diesters such as diethyl sebacate, and diisostearyl malate can also be used.

Further examples include silicone oils, such as linear silicones such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane; cyclic silicones such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane; amino-modified silicone oils, polyether-modified silicone oils, carboxy-modified silicone oils, alkyl-modified silicone oils, ammonium salt-modified silicone oils, and fluorine-modified silicone oils.

Further examples include hydrocarbon oils such as liquid paraffin, squalane, squalene, pristane, isoparaffin, α-olefin oligomers, and petrolatum.

Further examples include higher alcohols such as octyldodecanol, hexyldecanol, isostearyl alcohol, oleyl alcohol, cetanol, and behenyl alcohol.

Further examples include fatty acids such as oleic acid, linolenic acid, eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, arachidonic acid, lauric acid, myristic acid, palmitic acid, and stearic acid.

These oils may be solid or liquid at room temperature, but compositions with a high proportion of liquid oils are preferred, for example, from the perspective of imparting softness to the oil gel particles, visual transparency, and adjusting the IOB value. Depending on the specific purpose, one or more types can be combined and incorporated into the oil gel particles. For example, by using isononyl isononanoate or octyldodecanol, among these oils, it is possible to impart softness when crushed on the skin, a transparent appearance, and a moist feel to the oil gel particles.

In addition, by using silicone oil as an oil agent, the oil gel particles blend well with the skin, while also providing a moist and smooth feeling.

In addition, by using hydrocarbon oil as the oil agent, it is possible to impart a moist feeling to the skin in addition to the good skin-friendliness of the oil gel particles.

The oil content of the oil gel particles of this embodiment is 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more, based on the total amount of the oil gel particles, from the viewpoint of dissolving the oily gelling agent. Furthermore, in order to add and solidify the gelling agent, the content is 99% by mass or less, preferably 98.5% by mass or less, and more preferably 98.1% by mass or less.

To obtain transparent oil gel particles, an oil with a refractive index close to that of water, 1.333, must be used, and the oil's physical properties must have a specific balance of organic and inorganic properties. Regarding the physicochemical properties of the individual compounds contained in the oil, properties primarily due to van der Waals forces are called "organic," while properties primarily due to electrical affinity are called "inorganic." The physical properties of the compound can be determined by combining these. Each compound is assigned a unique characteristic value, known as the organic value (OV) or inorganic value (IV), and the organic and inorganic values of each compound are compared and adjusted to select an oil suitable for transparent oil gel particles.

For example, the upper limit of the IOB value of the oil agent is preferably 0.85 or less, more preferably 0.84 or less, and even more preferably 0.83. Here, the IOB value represents the ratio of inorganic value to organic value (inorganic organic balance) calculated based on the organic conceptual diagram (Fujita Atsushi, Prediction of Organic Compounds and Organic Conceptual Diagram, Chemistry Area Vol. 11, No. 10 (1957) 719-725), and is the value obtained by dividing the inorganic value by the organic value. When two or more oil agents are contained, the IOB value after mixing can be calculated as a weighted average. An IOB value of 0.85 or less can achieve the moist feel characteristic of oil gels. The IOB value may be 0, as in the case of squalane, a hydrocarbon oil, but is preferably greater than 0, more preferably 0.01 or greater, and even more preferably 0.015.

(Gelling Agent)
The gelling agent of component (B) used in the oil gel particles of the present invention is a component that gels the oil in a transparent to translucent state, imparts viscosity over a wide range, and improves stability over time and the feel when applied to the skin. Its content is 0.5% by mass or more, preferably 1% by mass or more, and more preferably 1.5% by mass or more, to solidify the particles. Furthermore, to prevent the particles from becoming too hard, its content is 50% by mass or less, preferably 45% by mass or less, and more preferably 40% by mass or less. Examples of preferred gelling agents used in this embodiment include dextrin fatty acid esters, inulin fatty acid esters, and/or amino acid-based oil gelling agents.

Dextrin fatty acid esters are esters of dextrin with a fatty acid or fatty acid derivative, preferably an ester of a higher fatty acid having 8 to 22 carbon atoms. The average degree of glycopolymerization of the dextrin is preferably 3 to 150, and the degree of fatty acid substitution per glucose unit of the dextrin is preferably 1.5 to 1.7. Specific examples include dextrin octanoate, dextrin laurate, dextrin palmitate, dextrin myristate, dextrin stearate, dextrin behenate, coconut oil fatty acid dextrin, and (palmitate/octanoate) dextrin. Commercially available products of these dextrin fatty acid esters include "Leopearl KL2," "Leopearl MKL2," "Leopearl TT2," and "Leopearl TL2" (all manufactured by Chiba Flour Milling Co., Ltd.). Of these, dextrin palmitate is most preferred in terms of stability over time and ease of use.

Inulin fatty acid esters are esters of inulin with a fatty acid or fatty acid derivative, preferably an ester of inulin with a linear or branched, saturated or unsaturated fatty acid having 8 to 32 carbon atoms, and the average molecular weight of the inulin is preferably in the range of 300 to 10,000. Specific examples include those described in JP-A-3-197409 and JP-A-2002-193732, and commercially available products include "Leopearl ISK2" (manufactured by Chiba Flour Milling Co., Ltd.).

The blending amount of the dextrin fatty acid ester and/or inulin fatty acid ester used in this embodiment is preferably 1 to 50% by mass, as this provides superior stability over time and spreadability, and is preferably 3 to 45% by mass, as this provides even superior spreadability.

A variety of amino acid-based oil gelling agents can be used in this embodiment. Among amino acid derivatives, N-acylamino acid esters and N-acylamino acid amides can be obtained, for example, by thermally reacting an N-acylamino acid with an alcohol or an amine, respectively, in the presence or absence of an acid catalyst, or by N-acylation of an amino acid ester or amino acid amide with an acylating agent such as a fatty acid halide. Furthermore, N-acylamino acid amine salts can be easily obtained by neutralizing an N-acylamino acid with an amine. Exemplary compounds of these compounds include N-lauroyl glutamic acid dilaurylamide, N-caproyl glutamic acid dilaurylamide, N-lauroyl glutamic acid dibutylamide, N-lauroyl glutamic acid stearylamide, Nα·Nω-dicaproyl lysine lauryl ester, Nα·Nω-distearoyl lysine octyl ester, N-stearoyl glycine laurylamide, N-palmitoyl-ε-aminocaproic acid lauryl ester, Nα-Nω-dicapryloyl lysine stearylamine, N-lauroyl valine laurylamine salt, N-lauroyl glutamic acid dioctylamide, and Nα·Nω-dilauroyl lysine stearylamine salt. The amount of amino acid oil gelling agent used in this embodiment is suitably 0.5 to 10.0%. If the amount is less than 0.5%, the gelling ability will be significantly reduced, and if the amount is increased beyond 10.0%, no significant effect can be expected.

(Surfactant)
The oil gel particles of the present embodiment may contain a surfactant from the viewpoint of improving the feel upon application and the solubility of added ingredients when the particles are incorporated into aqueous cosmetics, etc. The surfactant may be one or a mixture of two or more selected from nonionic surfactants, zwitterionic surfactants, etc.

Examples of nonionic surfactants include fatty acid sorbitan esters, polyoxyethylene fatty acid sorbitan, polyoxyethylene higher alcohol ethers, poly(oxyethylene-oxypropylene) higher alcohol ethers, polyoxyethylene fatty acid esters, polyoxyethylene alkylphenols, polyoxyethylene alkylamines, and polyoxyethylene-polyoxypropylene block polymers. Furthermore, examples of zwitterionic surfactants include dimethyl alkyl betaines and alkylamido betaines.

When a surfactant is used, the amount of surfactant added is 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.15% by mass or more, and even more preferably 0.2% by mass or more, relative to the total amount of oil gel particles. If the amount is less than 0.05% by mass, the effect of adding the surfactant will be insufficient. The upper limit for the amount of surfactant added is 10% by mass or less, preferably 8% by mass or less, and more preferably 6% by mass or less, relative to the total amount of oil gel particles. If the amount exceeds 10% by mass, emulsification may occur during granulation, which may impair the transparency of the oil gel, and this is not preferred.

In the oil gel particles of this embodiment, the combined HLB value of the oil and surfactant is preferably 8.5 or less. The oil and surfactant may be a mixture of two or more types. Here, the HLB value represents the degree of hydrophilicity or lipophilicity (hydrophobicity) of a surfactant, and refers to the HLB value at 25°C as defined by Griffin. The Griffin HLB value is defined in J. Soc. Cosm. Chem., 1954, 5:249-256. Furthermore, the concepts of organic and inorganic values of oils in the organic conceptual diagram are highly correlated with the concepts of hydrophilicity and lipophilicity in the HLB method. When comparing the value calculated from the ratio of organic and inorganic values (IV/OV = IOB (Inorganic Organic Balance)) with the HLB value, the approximate formula HLB value = IOB value x 10 holds.

Therefore, in this specification, the mixed HLB value refers to the HLB value of a mixture of one or more oils and one or more surfactants, and is the weighted average of the HLB values of each oil and surfactant based on their mass content ratio, and is calculated using the following formula:

Mixed HLB value = Σ(10×IOBx×Wx)/ΣWx+Σ(HLBy×Wy)/ΣWy
(IOBx represents the IOB value of oil agent X, Wx represents the mass (g) of oil agent X, HLBy represents the HLB value of surfactant Y, and Wy represents the mass (g) of surfactant Y.)

This mixed HLB value may be 0, but from the perspective of making the oil gel particles more compatible with water when used in aqueous cosmetic formulations, it is more preferable that the mixed HLB value is greater than 0, more preferably 0.1 or greater, and even more preferably 0.15 or greater. Furthermore, to enable particle formation without emulsification, the HLB value is preferably 8.5 or less, more preferably 8.4 or less, and even more preferably 8.3 or less.

(Manufacturing method)
The method for producing oil gel particles of this embodiment is preferably carried out as follows. First, an oil agent and a gelling agent are mixed and adjusted to a temperature above the melting point of the oily component (usually a temperature above the melting point of the gelling agent) to form a liquid. This mixture is then introduced under stirring into an aqueous solvent adjusted to a temperature low enough to prevent emulsification but high enough to disperse the oily component by stirring (15 to 75°C, with 30 to 60°C being particularly preferred). The mixture of aqueous solvent and oily component is then further cooled under stirring (preferably to room temperature) to form oil gel particles in the aqueous solvent. Examples of aqueous solvents that can be used include water, ethanol, glycerin, butylene glycol, and dipropylene glycol, which can be used alone or in suitable combinations. Thickeners, surfactants, and the like may also be added.

As mentioned above, the main factors determining the size of oily particles are the stirring speed of the aqueous solvent and the temperature of the aqueous solvent when the oily component is introduced. The stirring speed of the aqueous solvent is relatively slow, specifically, 10 to 1500 rpm, preferably 20 to 300 rpm, and can be performed using a propeller, paddle mixer, or the like. The higher the rotation speed, the smaller the oily particle diameter tends to be, while the lower the rotation speed, the larger the oily particle diameter tends to be. Furthermore, as mentioned above, the temperature of the aqueous solvent when adding the oily component is preferably 15 to 75°C, with approximately 30 to 60°C being particularly preferred. In other words, if the oily component is added to an aqueous solvent at a temperature below 15°C, it will solidify before forming spherical particles, tending to produce large, irregular particles. Furthermore, if the temperature of the aqueous solvent is higher than 75°C, the viscosity of the oily component decreases, and the particles are broken down by the stirring force, tending to result in particles smaller than the desired size.

The oily component can be introduced into the aqueous solvent by, for example, injecting it from above the aqueous solvent or directly into the aqueous solvent via a nozzle or other means using a liquid delivery device such as a liquid delivery pump.

Next, this mixture of aqueous solvent and oily component is cooled, preferably to room temperature, while stirring. The gelling agent in the oily component, now below its melting point, solidifies the oil. This allows oil gel particles to form in the aqueous solvent.

After producing oil gel particles in an aqueous solvent in this manner, the particles are typically separated from the aqueous solvent and dried. There are no particular limitations on the means for this separation and drying. For example, one method is to filter the oil gel particles dispersed in an aqueous solvent through a mesh smaller than the particle size and then dry them. The dried oil particles can be used as a granular skin preparation as is, but to prevent the particles from welding together, fine powder particles can be attached to the surface of the oil gel particles, or the particles can be dispersed in an aqueous gel to form a skin preparation. Furthermore, by using a powder of a water-soluble medicinal ingredient as the fine powder particles, the oil particles can be given the functions of the water-soluble medicinal ingredient (whitening effect, preventing dullness, preventing rough skin, moisturizing effect, etc.).

(Skin external composition)
The oil gel particles produced as described above can be dispersed in an aqueous or oily medium and used as external skin preparations, mainly cosmetics, pharmaceuticals, quasi-drugs, etc. External skin compositions include cosmetics, quasi-drugs, and external pharmaceuticals, and examples thereof include gels, emulsions, beauty serums, creams, lotions, beauty oils, hair oils, essences, packs, lipsticks, foundations, liquid foundations, press powder makeup, blushers, face powders, facial cleansers, body shampoos, slimming agents, hair shampoos, soaps, and also include hair growth agents and bath additives, but are of course not limited to these.

(Other ingredients)
The topical composition may contain water-soluble or oil-soluble components (water-soluble components are contained in the aqueous phase, and oil-soluble components are contained in the oil gel particles). For example, when the topical composition is used as a sun care product, it may contain an ultraviolet screening agent. It may also contain medicinal ingredients such as vitamins, hormones, amino acids, anti-inflammatory agents, antibacterial agents, whitening agents, astringents, cooling agents, and sterols. It may also contain extracts derived from animals, plants, or microorganisms that have various medicinal effects.

The oil-based component contains oil-soluble active ingredients, such as oil-soluble vitamins or oil-soluble vitamin derivatives, such as retinol, retinol palmitate, retinol acetate, tocopherol acetate, and ascorbyl tetra-2-hexyldecanoate, and these active ingredients are encapsulated in oil gel particles to provide whitening, anti-dullness, anti-roughness, moisturizing, and other effects. The oil gel particles can be applied efficiently as a skin preparation to areas with skin problems such as rough skin, dullness, and blemishes. Furthermore, because they contain almost no water, they can stabilize pharmaceuticals that are unstable in the presence of water, such as vitamins.

The oil gel particles can be colored by adding to the oil solution oil-soluble dyes (e.g., Red 225), organic pigments (e.g., Orange No. 204, Red No. 202), lakes of colorants (e.g., Orange No. 205, Yellow No. 4, Blue No. 1), lakes with zirconium, barium, aluminum, etc., natural pigments (e.g., chlorophyll, β-carotene), inorganic pigment powders (hydrophobized products are preferred) such as yellow iron oxide, red iron oxide, black iron oxide, titanium oxide, and zinc oxide, pearl pigments such as titanium mica, and glitter agents made from colored plate-like resins. The topical composition of this embodiment can also contain humectants, sequestering agents, neutralizers, pH adjusters, antioxidants, etc.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way. In the following examples, the unit % used to indicate the amount of each component added means % by mass.

[Production Example 1] Method for Producing Oil Gel Particles Oil gel particles were produced by the following method using appropriate combinations of the various components listed in Table 1. Specifically, the oil gel components shown in Tables 2 to 4 (oil agent, gelling agent, and optionally surfactant or functional component) were thoroughly mixed at room temperature and then heated to 140°C in an oil bath to dissolve. 100 g of purified water was added to a separate container, which was then immersed in a hot water bath, adjusted to 40°C, and stirred. 0.5 g of each oil gel component was added to a stirring container containing purified water, stirred for 30 seconds to 1 minute, and particle formation was confirmed. The mixture was then passed through a sieve with 2.35 mm openings and then recovered using a sieve with 1 mm openings. The particles were then washed with water, sized, and dried for one day to produce oil gel particle samples.

[Test Example 1] Appearance Evaluation 1. Particle Formation Ability After adding the oil phase (oil gel component) to the water phase (purified water) and stirring, if a spherical gel was formed, it was rated as ◯; if it did not emulsify to form particles or if it formed a plate-like or string-like gel instead of a spherical one, it was rated as ×; and if it formed an almost spherical gel, it was rated as △.
2. Transparency After sieving and recovering the spherical gel, if a transparent gel was formed by visual inspection, it was rated as ◯; if it was slightly cloudy and semi-transparent due to emulsification or crystallization, it was rated as △; if it was cloudy and opaque due to emulsification or crystallization, it was rated as ×.
3. Durability during sieving After collecting the spherical gel through a sieve, if the shape did not change before and after washing with water, it was evaluated as ◯; if the shape changed or collapsed before and after washing with water, it was evaluated as ×; and if the shape hardly changed before and after washing with water, it was evaluated as △.

[Test Example 2] Sensory evaluation When oil gel particles were picked up and crushed on the skin, those that were easy to crush and spread were rated as ◯, and those that were difficult to crush and spread were rated as ×. ⊚ indicates that the particles were particularly easy to spread and smooth.

[Test Example 3] Instrumental Measurement The breaking strength of the oil gel particles was measured using a rheometer (RHEO METER, MODEL: CR-3000EX) manufactured by Sun Scientific Co., Ltd. The breaking strength was measured in advance using a thickness gauge and then subjected to measurement with the rheometer. The breaking strength was measured using a rheometer equipped with a jig with a diameter of 12 mm, and the sample was placed on a disc-shaped sample stage in the measurement section of the rheometer and raised at a rate of 5 mm/min. The penetration distance was approximately half the particle size, and the jig was inserted from a state in which the sample and the jig were in contact, and then compressed to break. At this time, breakage was confirmed visually and by touch, and the breaking strength was determined from the load-strain curve. This measurement was repeated for three samples, and the average value was calculated.
The thickness of the oil gel particles used in the measurement was measured and used as the particle size of the sample, the area was calculated from this particle size, and the load (N) measured previously was divided by the cross-sectional area to obtain the breaking strength (kPa). This "particle size of the sample" was then used as the average particle size.

[Examples 1 to 7 and Comparative Example 1] Investigation of the polarity of oil agents and surfactants First, oil gel particles were produced according to the method of Production Example 1 using oil gel components of each composition shown in Table 2. Under the conditions of Examples 1 to 3, which did not contain a surfactant, the formation of transparent particles was observed, and the IOB values of the oil agents at this time were 8.1 or less. Furthermore, under the conditions where a surfactant was added, the formation of transparent particles was observed in Examples 4 to 6, but no particle formation was observed in Comparative Example 1, suggesting that particle formation is difficult when the mixed HLB value of the oil gel components exceeds 8.5.

[Examples 8 to 15 and Comparative Example 2] Study of the hardness of oil agent and gelling agent Next, in order to study the influence of oil agent and gelling agent on the hardness of oil gel particles, oil gel particles were produced according to the method of Production Example 1 using oil gel components of each composition shown in Table 3. Although the strength varied depending on the combination of gelling agent and oil agent, it was confirmed that particle formation and sieving were possible within the range of 2 to 50% gelling agent, and it was also found that the particles of Example 11, in which 35% gelling agent was added, were easy to crush and had a good feel.

[Examples 16-25] Study of Additional Components In order to investigate the effects of adding additional components such as various functional components to oil gel particles, oil gel particles were prepared according to the method of Preparation Example 1 using the oil gel components of each composition shown in Table 4. As a result, it was confirmed that particles were formed and had physical properties similar to those of the unencapsulated particles in terms of transparency and hardness. As shown in Table 4, Example 16 contained silicone oil, Example 17 contained sodium hyaluronate, Example 18 contained ascorbic acid, Example 19 contained retinol, Example 20 contained fragrance (limonene, linalool), Example 21 contained powder (sodium carbonate), Example 22 contained pigment (ultramarine), Example 23 contained vegetable oil (palmitic acid), Example 24 contained vegetable oil (stearic acid), and Example 25 contained an ultraviolet absorber (ethylhexyl methoxycinnamate).

[Production Example 2] Investigation of the method for producing oil gel particles For the components of Example 26 listed in Table 5, oil gel particles were produced in the same manner as in Production Example 1, except that the receiving liquid was changed to 10 g of glycerin and 90 g of purified water, and then evaluated.

[Production Example 3] Method for producing oil gel particles For the components of Example 27 listed in Table 5, oil gel particles were produced in the same manner as in Production Example 1, except that the receiving liquid was changed to 90 g of glycerin and 10 g of purified water, and then evaluated.

[Production Example 4] Method for producing oil gel particles For the components of Example 28 listed in Table 5, oil gel particles were produced in the same manner as in Production Example 1, except that the receiving liquid was changed to 10 g of 1,3-butylene glycol and 90 g of purified water, and then evaluated.

[Production Example 5] Method for producing oil gel particles For the components of Example 29 listed in Table 5, oil gel particles were produced in the same manner as in Production Example 1, except that the receiving liquid was changed to 90 g of 1,3-butylene glycol and 10 g of purified water, and then evaluated.

[Production Example 6] Method for producing oil gel particles For the components of Example 30 listed in Table 5, the receiving liquid was changed to 0.1 g of carboxyvinyl polymer, 0.1 g of polysorbate 80, 10 g of 1,3-butylene glycol, and 89.8 g of purified water, and the oil gel particles were produced in the same manner as in Production Example 1, and evaluated.

[Production Example 7] Method for producing oil gel particles For the components of Example 32 listed in Table 5, oil gel particles were produced in the same manner as in Production Example 1, except that the receiving liquid was changed to 50 g of glycerin and 50 g of purified water, and then evaluated.

[Production Example 8] Method for producing oil gel particles The components of Example 31 listed in Table 5 were heated to 140°C and melted, and then filled into a silicon mold in the form of particles with a particle size of 2 mm. After cooling at room temperature for one day, the particles were peeled off from the mold to obtain oil gel particles, which were then sieved in the same manner as in Production Example 1 and evaluated.

[Formulation example of a topical skin composition containing oil gel particles]
Formulation examples in which oil gel particles were blended in the examples are shown below. In all formulation examples, the formulation was prepared using ingredients other than the oil gel particles, and then the oil gel particles were added and mixed last to prepare the formulation example.

Example 33: Stability Test of Retinol Encapsulated in Oil Gel Particles The stability of retinol, a functional ingredient effective in improving wrinkles, encapsulated in oil gel particles was examined. Isononyl isononanoate was mixed with dextrin palmitate and silica in the amounts shown in Table 11, and the mixture was heated to 110°C to dissolve the oil gel component. In a separate container, polysorbate 80 was dissolved in a glycerin aqueous solution and heated to 50°C. Retinol and tocopherol were added to the oil gel component container and dissolved, and then the oil gel component was added to the glycerin aqueous solution containing polysorbate 80 while stirring to produce oil gel particles. The formed particles were collected using a 100-mesh filter and immersed in the outer layer solution shown in Table 11. The mixture was divided into glass bottles, wrapped in aluminum foil to protect from light, and then stored refrigerated (5°C) or at 40°C, or stored unprotected under natural light (by a window). After storage for a predetermined period, the amount of retinol remaining in the stored samples was quantified by HPLC using the following procedure: As a control, retinol was dissolved in ethanol to a concentration of 0.1 wt/vol % and stored under the same conditions as the above samples.

<HPLC conditions>
Measurement conditions Column: COSMOSIL 5C18-MS-II Packed Column 4.6 mm ID x 250 mm
Solvent: ethanol/water (95/5)
Flow rate: 1 ml/min Detection: UV 325 nm
Injection volume: 10μl

The samples stored under each condition were mixed with the above solvent (ethanol/water (95/5)) and disrupted by ultrasound. The retinol concentration was adjusted to 20 μg/mL and used as a sample for HPLC measurement. The retinol concentration after each storage period was quantified by HPLC, and the remaining amounts after 1 day and 14 days, with the retinol concentration on day 0 set at 100, are shown in Table 12 below.

<HPLC results>

As shown in Table 12, retinol encapsulated in oil gel particles was more stable than retinol in ethanol solution under all conditions. In particular, retinol stored in ethanol solution at 40°C under light-protected conditions was almost completely decomposed after one day, whereas 97% of retinol encapsulated in oil gel particles remained even after 14 days of storage at 40°C under light-protected conditions, demonstrating that encapsulation in oil gel particles stabilizes retinol. Furthermore, when stored under natural light, retinol stored in ethanol solution was completely decomposed after one day, whereas approximately 58% remained when encapsulated in oil gel particles.

Example 34 Stability Test of Retinol Palmitate Encapsulated in Oil Gel Particles A storage sample was prepared in the same manner as in Example 33, except that retinol palmitate was used instead of retinol. The compositions of the oil gel particles and outer layer liquid are shown in Table 13 below. As a comparative control, retinol palmitate was dissolved in ethanol to a concentration of 1 wt/vol % and stored in the same environment as the above sample.

<HPLC conditions>
Measurement conditions Column: COSMOSIL 5C18-MS-II Packed Column 4.6 mm I.D. × 250 mm
Solvent: ethanol/water (95/5)
Flow rate: 1 ml/min Detection: UV 325 nm
Injection volume: 10μl

The samples stored under each condition were mixed with the above solvent (ethanol/water (95/5)) and disrupted by ultrasound. The concentration was adjusted to 13 ppm (wt/vol) and used as a sample for HPLC measurement. The retinol palmitate concentration after each storage period was quantified by HPLC, and the remaining amounts after 1 day and 14 days, assuming the retinol palmitate concentration on day 0 (the start of each storage period) as 100, are shown in Table 12 below.

As shown in Table 14, retinol palmitate stored in solution was almost completely decomposed after 14 days, even at 25°C under light-protected conditions. However, more than 97% of retinol encapsulated in oil gel particles remained after 14 days at both 25°C and 40°C, demonstrating that encapsulation in oil gel particles stabilizes the retinol. When stored under natural light, retinol stored in ethanol solution was almost completely decomposed after one day, but when encapsulated in oil gel particles, approximately 69% remained.

Examples 35 to 40 Evaluation of Oil Gel Particle-Containing Compositions for Topical Skin Use In order to examine the feel and dispersibility of oil gel particles dispersed in an oily medium, oil gel particles were prepared according to the method of Production Example 1 using the components shown in Table 15 (isononyl isononanoate and dextrin palmitate). After particle formation, the particles were passed through a sieve with a mesh size of 1.4 mm and then recovered using a sieve with a mesh size of 0.5 mm, and dispersed in the outer layer liquid shown in Table 15 at a weight ratio of oil gel particles:outer layer liquid = 1:9. The feel and dispersibility of the oil gel particles were then evaluated by the following method.

Evaluation method: Feeling: After the oil gel particles dispersed in the outer layer liquid were picked up and spread on the skin, those that stretched were rated as ◯, and those that did not stretch were rated as ×.
Dispersibility: The oil gel particles dispersed in the outer layer liquid were filled into the cell of a spectrophotometer (Single monochromator UV-2600i, Shimadzu Corporation), and the state of dispersion was visually evaluated after one day. Figure 1 shows an overview of this dispersibility (absorbance test). Uniform dispersion was evaluated as ◯, partial sedimentation as △, and complete sedimentation as ×. Simultaneously, the absorbance (660 nm) of the particles + outer layer liquid was measured using only the outer layer liquid as a blank. In addition, the percentage change in absorbance between immediately after filling and after leaving to stand for one day was calculated using the following [Equation 1]. The results are shown in Table 15.
[Formula 1]
Absorbance change rate (%) = (absorbance (1 day after filling) / absorbance (immediately after filling)) x 100

As shown in Table 15, it was confirmed that a topical skin composition with a specified outer layer liquid composition can be prepared that has oil gel particle dispersion and a pleasant feel.

[Examples 41 and 42]: Oil gel particles The oil gel particles shown in Table 16 were prepared. Example 41 is an example in which an enzyme (protease) is encapsulated as the encapsulated functional component. Example 42 is an example in which a specific colorant (a component or pigment used in makeup, etc.) is encapsulated as the encapsulated functional component.

The oil gel particles described in Example 41 in Table 16 were prepared as follows. The oil gel components (oil, etc.) shown in Example 41 were thoroughly mixed at room temperature (25°C) and then heated to 110°C in an oil bath to dissolve. 0.5 g of each oil gel component was added to a stirring vessel containing 100 g of glycerin, and the mixture was stirred for 30 seconds to 5 minutes to confirm particle formation. The mixture was then passed through a sieve with 2.35 mm openings and then recovered through a sieve with 1 mm openings. The particles were then washed with water, sized, and dried for one day to prepare the oil gel particle samples described in Table 16. The prepared oil gel particles were also evaluated for appearance, etc. (evaluated in the same manner) as listed in Tables 1 to 3, as shown in Table 16.

The oil gel particles described in Example 42 in Table 16 were prepared as follows. The oil gel components (oil, etc.) shown in Example 42 were thoroughly mixed at room temperature (25°C) and then heated to 110°C in an oil bath to dissolve. 75 g of glycerin and 25 g of purified water were added to a separate container and stirred. 0.5 g of each oil gel component was added to a stirring container containing glycerin and purified water, and stirred for 30 seconds to 5 minutes to confirm particle formation. The mixture was then passed through a sieve with 2.35 mm openings and then recovered through a sieve with 1 mm openings. The particles were then washed with water, sized, and dried for one day to prepare the oil gel particle samples described in Table 16. The prepared oil gel particles were also evaluated for appearance, etc. (evaluated in the same manner) as listed in Tables 1 to 3, as shown in Table 16.

The components contained in the oil gel particles shown in Table 16 were the same as those listed in Table 1 above, except for the following: protease: Protease CL-15, Nagase ChemteX Corporation; yellow iron oxide: Tarox LL-100P, Titanium Kogyo Co., Ltd.; red iron oxide: Tarox R-516P, Titanium Kogyo Co., Ltd.; black iron oxide: Tarox BL-100, Titanium Kogyo Co., Ltd.; titanium oxide: MT-500B, Teika Corporation

The oil gel particles produced in Example 41 contained an enzyme that was not inactivated. Accelerated degradation tests based on the Arrhenius equation (Sakagami Shigeyuki, Kawase Akito: Storage Stability Tests for Pharmaceuticals, SCAS NEWS, 2000-1, pp. 7-11) were conducted on the oil gel of Example 41 at 40°C for one month and at 50°C for one month. The results of the tests showed that the enzyme was inactivated within one month under both conditions.

The oil gel particles produced in Example 42 are crushed and applied to the skin, spreading the makeup ingredients over the skin, providing an emollient effect and making it easy to experience the makeup effect. The oil gel particles of Example 42 are particles in which the makeup ingredients are solidified in particulate form, and the particles themselves have a makeup effect. The oil gel particles of Example 42 can eliminate the need to uniformly mix the makeup ingredients into a base material when producing cosmetics containing these oil gel particles. Note that the oil gel particles of Example 42 were not transparent because they contained the specified amounts of the pigment and titanium oxide.

Table 17 below shows an example formulation of a topical skin composition containing the oil gel particles of Example 42. As shown in Table 6 above, the formulation was prepared using ingredients other than the oil gel particles, and then the oil gel particles of Example 42 were added and mixed to create the formulation.

[Production Example 9] Investigation of the Production Method of Oil Gel Particles The oil gel particles of Example 43 listed in Table 18 were produced as follows. The oil gel components (oil, etc.) shown in Table 18 were thoroughly mixed at room temperature (25°C) and then heated to 110°C in an oil bath to dissolve. 0.5 g of each oil gel component was added to a stirring vessel containing 100 g of glycerin, and the mixture was stirred for 30 seconds to 5 minutes to confirm particle formation. The particles were then passed through a sieve with 2.35 mm openings and then recovered using a sieve with 1 mm openings. Subsequently, the particles were washed with water, sized, and dried for one day to produce the oil gel particle samples listed in Table 18. The produced oil gel particles were also evaluated for appearance, etc. (evaluated in the same manner) as listed in Tables 1 to 3, as shown in Table 18.

As shown in Table 18, oil gel particles were produced that met the required evaluation results (particle formation ability, etc.).

[Examples 7 to 9]: Mixtures containing oil gel particles of Example 33 The oil gel particles of Example 33 were used to prepare the examples (mixtures) shown in Table 19 below. The examples were prepared by adding a lubricant or silk powder to the oil gel particles of Example 33 and mixing them in the compositions shown in Table 19.

In the examples shown in Table 19, the following lubricants or silk powders were used.
Lubricant (Lauroyl Lysine): Amihope ^™ LL, Ajinomoto Co., Inc. Lubricant (Talc): Crown Talc JS, Matsumura Sangyo Co., Ltd. Silk powder: Silkgen G Powder (N), Ichimaru Pharcos Co., Ltd.

In the examples shown in Table 19, the lubricant or silk powder is adsorbed onto the surface of the oil gel particles, suppressing adhesion between particles and increasing the fluidity of the oil gel particles. This improvement makes it easier for cosmetic formulators to handle the oil gel particles as granules. By using the examples shown in Table 19, it is easier to create cosmetics that, when crushed, give the feeling of directly rubbing oil in and have a more emollient effect.

It has been confirmed that the oil gel particles of the present invention have a highly transparent appearance and, when applied to the skin, have the moist feel characteristic of oily agents. Therefore, the oil gel particles of the present invention and topical preparations containing them can be used as facial, body, or hair cosmetics, such as lotions, emulsions, creams, and packs.

Claims (5)

The oil gel particles comprise 50 to 99% by mass of an oil agent, 0.5 to 50% by mass of a gelling agent, and 0.5 to 10% by mass of a surfactant, and the oil agent and the surfactant have a mixed HLB value of 8.5 or less . 2. The oil gel particles according to claim 1 , wherein the average particle size is 100 to 2000 μm. 3. The oil gel particles according to claim 1 , wherein the oil agent is at least one selected from the group consisting of hydrocarbon oils, ester oils, silicone oils, and vegetable oils. 4. The oil gel particles according to claim 1 , wherein the gelling agent is a dextrin fatty acid ester, an inulin fatty acid ester, and/or an amino acid-based oil gelling agent. A composition for external use on skin, comprising the oil gel particles according to any one of claims 1 to 4 in a dispersed state in an aqueous or oily medium.