JP7462455B2 - Oil-in-water emulsion composition - Google Patents

Description

The present invention relates to an oil-in-water emulsion composition.

In general, the continuous phase of an oil-in-water emulsion composition is composed of an aqueous component, and therefore when used as a cosmetic, it has the following characteristics: (1) it spreads lightly and smoothly, and leaves a refreshing feeling when used, (2) it is relatively easy to manufacture, (3) it is not easily affected by temperature, and (4) by changing the type and amount of oil, it is possible to vary the feel and properties and spread the composition in various ways.

In oil-in-water emulsion compositions, ester oils and vegetable oils are sometimes used as the oil agent. Furthermore, attempts have been made to reduce the particle size of emulsion droplets in oil-in-water emulsion compositions that use vegetable oils, etc.

For example, Patent Document 1 discloses a technique for reducing the emulsion particle size to 5 μm or less using a viscous substance such as a glutamic acid polypeptide and a surfactant containing a polyhydroxy compound. It is difficult to obtain a stable oil-in-water emulsion composition due to the high polarity of vegetable oils, and it is said that the above-mentioned composition makes it possible to reduce the emulsion particle size to fine particles of 5 μm or less.

Japanese Patent Application Laid-Open No. 11-18696

However, even with the technology disclosed in Patent Document 1, the stability of the oil-in-water emulsion composition was not sufficient, and there was room for improvement.

The present invention aims to provide an oil-in-water emulsion composition that uses an ester oil and/or vegetable oil as an oil agent and has high formulation stability (emulsion stability and stability over time).

Yet another object of the present invention is to provide an oil-in-water emulsion composition that can impart a glossy feel to the skin when applied to cosmetics.

The present invention is an oil-in-water emulsion composition that contains the following components (A) to (D): (A) at least one selected from the group consisting of ester oils that are liquid at 25°C and vegetable oils that are liquid at 25°C, (B) polyoxyethylene hydrogenated castor oil having an average number of moles of ethylene oxide added of 20 to 30, (C) at least one selected from sorbitan monoisostearate and sorbitan diisostearate, and (D) water, in which the mass ratio (B)/(C) of component (B) to component (C) is greater than 1 and less than 20, and the average particle size of the emulsion particles is 300 nm or less.

According to the present invention, even when ester oil or vegetable oil is used as the oil agent, the emulsion stability is high immediately after production and over time. Furthermore, when the oil-in-water emulsion composition is applied to the skin as a cosmetic, it can impart a glossy feel to the skin.

The following describes the embodiments of the present invention. Note that the present invention is not limited to the following embodiments. In this specification, the range "X to Y" includes X and Y and means "X or more and Y or less." Furthermore, unless otherwise specified, operations and measurements of physical properties are performed under conditions of room temperature (20 to 25°C) and relative humidity of 40 to 50% RH.

One embodiment of the present invention is an oil-in-water emulsion composition that contains the following components (A) to (D): (A) at least one selected from the group consisting of ester oils that are liquid at 25°C and vegetable oils that are liquid at 25°C, (B) polyoxyethylene hydrogenated castor oil having an average number of moles of ethylene oxide added of 20 to 30, (C) at least one selected from sorbitan monoisostearate and sorbitan diisostearate, and (D) water, in which the mass ratio (B)/(C) of component (B) to component (C) is greater than 1 and less than 20, and the average particle size of the emulsion particles is 300 nm or less.

When an oil-in-water emulsion is made using ester oil liquid at 25°C and/or vegetable oil liquid at 25°C (hereinafter also referred to simply as ester oil, etc.) of component (A), the formulation stability tends to become unstable as described above. However, by combining components (B) and (C) and setting the average particle size of the emulsion particles to 300 nm or less, the initial stability and stability over time can be ensured. This is thought to be because the average particle size of the emulsion particles is sufficiently small at 300 nm or less, so that the initial stability is guaranteed, and the combination of components (B) and (C) can stabilize the interface of oil droplets containing ester oil, etc., and stability over time is maintained. The emulsion stability of oil agents in oil-in-water emulsions is often examined based on the balance of HLB of the surfactant, but the present inventors have found that in fine emulsions of ester oil, etc., the stability of the emulsion is not guaranteed by the balance of HLB of the surfactant alone. They also discovered that the type of surfactant and the combination of surfactants are important for the stability of fine emulsions of ester oils, etc., and that among the many types of surfactants available, the combination of component (B) and component (C) is extremely important.

Furthermore, by setting the average particle size of the emulsion particles to 300 nm or less, when applied as a cosmetic, the skin permeability is increased, and the effect of the oil agent is more easily exerted. In addition, by adopting the configuration of this embodiment, it is possible to impart a glossy feel to the skin when applied to the skin.

The oil-in-water emulsion composition of this embodiment is preferably liquid at 25°C. It is generally more difficult to ensure the formulation stability of a liquid oil-in-water emulsion composition than one that has viscosity. This embodiment ensures emulsion stability and stability over time, despite being liquid at 25°C. In this specification, being liquid at 25°C means being in a state of having fluidity at 25°C. Specifically, this refers to a viscosity measured at 25°C using a Brookfield rotational viscometer of 10,000 mPa·s or less, preferably 5,000 mPa·s or less, and more preferably 2,000 mPa·s or less.

In addition, the oil-in-water emulsion composition of this embodiment preferably has a transparent to translucent appearance.

From the viewpoint of stability over time, the average particle size of the emulsion particles in the oil-in-water emulsion composition is 300 nm or less, preferably 200 nm or less, and more preferably 150 nm or less. The lower limit of the average particle size of the emulsion particles in the oil-in-water emulsion composition is not particularly limited because the smaller the particle size, the better the formulation stability, but is usually 10 nm or more. Such fine emulsion particles can be obtained, for example, by a phase inversion temperature emulsification method, as described later. Therefore, a preferred embodiment of the present invention is an oil-in-water emulsion composition obtained by a phase inversion temperature emulsification method.

The average particle size of the emulsified particles is the value measured in the examples.

(Component (A): Ester oil that is liquid at 25° C. and/or vegetable oil that is liquid at 25° C.)
The ester oil and/or vegetable oil that are liquid at 25° C. as component (A) have a high refractive index, and when applied to the skin as a cosmetic, can impart a glossy feel to the skin and a moist feel to the skin.

Examples of ester oils include esters of linear or branched fatty acids and linear or branched monohydric or polyhydric alcohols. Ester oils that are liquid at 25°C preferably do not have a hydroxyl group. Examples of ester oils that are liquid at 25°C include glyceryl tri-2-ethylhexanoate, glyceryl diisostearate, diglyceryl diisostearate, glyceryl triisostearate, diglyceryl triisostearate, trimethylolpropane triisostearate, diglyceryl tetraisostearate, polyglyceryl decaisostearate, isotridecyl isononanoate, pentaerythritol tetra-2-ethylhexanoate, pentaerythritol tetraisostearate, cetyl 2-ethylhexanoate, octyldodecyl oleate, caprylic/capric triglyceride, propylene glycol dicaprate, isopropyl myristate, isopropyl palmitate, octyldodecyl myristate, isocetyl stearate, neopentyl glycol dioctanoate, di-2-ethylhexyl succinate, 2-ethylhexyl paramethoxycinnamate, and ethylhexyl salicylate.

As for the ester oil that is liquid at 25°C (hereinafter, when simply referring to ester oil, it refers to an ester oil that is liquid at 25°C), it is preferable that the fatty acid that constitutes the ester has a branch or a double bond. Ester oils in which the fatty acid that constitutes the ester has a branch or a double bond can shake the intercellular lipids of the skin, and the oil agent has good permeability into the skin, and the effect of the oil agent, such as softness of the skin after application, is easily obtained. On the other hand, these oil agents tend to destabilize the interface structure of the emulsion droplets of the oil agent, and the emulsion stability is easily unstable. However, in this embodiment, even when these oil agents are used, fine emulsion droplets are stably formed by combining component (B) and component (C). Examples of ester oils that are liquid at 25°C and in which the fatty acids that make up the ester have branched or double bonds include glyceryl tri-2-ethylhexanoate, glyceryl diisostearate, diglyceryl diisostearate, glyceryl triisostearate, diglyceryl triisostearate, trimethylolpropane triisostearate, diglyceryl tetraisostearate, polyglyceryl decaisostearate, isotridecyl isononanoate, pentaerythritol tetra-2-ethylhexanoate, pentaerythritol tetraisostearate, and cetyl 2-ethylhexanoate.

Furthermore, the molecular weight of the ester oil is preferably 400 or more. When applied to the skin as a cosmetic, ester oils with a molecular weight of 400 or more have the effect of imparting a more glossy feel, but they tend to destabilize the interface structure of the emulsion droplets of the oil agent, which tends to make the emulsion stable. However, in this embodiment, even when an oil agent with a relatively large molecular weight is used, fine emulsion droplets are stably formed by combining components (B) and (C). The molecular weight of the ester oil is more preferably 500 or more, and even more preferably 600 or more. The upper limit of the molecular weight of the ester oil is not particularly limited, but is usually 1500 or less.

Component (A) may be a vegetable oil. The vegetable oil is preferably composed of an ester oil. Vegetable oil has a relatively high refractive index and is likely to impart a glossy feel when applied to the skin, but vegetable oil is usually a mixture of multiple fatty acid ester oils and has an uneven molecular weight distribution. This makes it difficult to perform fine emulsification and also makes it difficult to ensure stability over time. However, in this embodiment, even when vegetable oil is used, fine emulsion droplets are stably formed by combining components (B) and (C).

Examples of vegetable oils that are liquid at 25°C include olive oil, macadamia nut oil, meadowfoam oil, jojoba oil, avocado oil, castor oil, safflower oil, sunflower oil, canola oil, apricot kernel oil, rice germ oil, and rice bran oil.

As for the vegetable oil, it is preferable that the fatty acid of the fatty acid ester constituting the vegetable oil has a double bond and contains 70 mol % or more of unsaturated fatty acids with 12 to 22 carbon atoms. The use of such vegetable oil is preferable in that the oil agent has good permeability into the skin and gives the skin a plump and firm look. As the vegetable oil, olive oil, macadamia nut oil, meadowfoam oil, and jojoba oil are preferable, and olive oil and macadamia nut oil are more preferable.

Component (A) preferably has a refractive index of 1.40 or more. When component (A) has a refractive index of 1.40 or more, it provides a suitable glossy feel when applied to the skin.

In a preferred embodiment, component (A) is at least one selected from the group consisting of ester oils and vegetable oils having a molecular weight of 400 or more, as this can further improve the glossiness of the cosmetic.

Component (A) may be used alone or in combination. For example, ester oils that are liquid at 25°C may be used alone or in combination, vegetable oils that are liquid at 25°C may be used alone or in combination, or an ester oil that is liquid at 25°C and a vegetable oil that is liquid at 25°C may be used in combination.

In the oil-in-water emulsion composition of the present invention, even if component (A) is blended in the oil agent at a high concentration of 60% by mass or more, an oil-in-water emulsion composition with excellent stability can be obtained. Since a high concentration of ester oil or the like can be blended in the oil agent, for example, when used in a basic cosmetic such as a lotion, it is expected that the sensory range of the component (A) can be expanded to impart a glossy feel. In addition, in the system of this embodiment, from the viewpoint of emulsion stability, it is preferable that component (A) is blended in the oil agent at a concentration of 60% by mass or more. Therefore, the content of component (A) in the oil agent is preferably 60% by mass or more, 70% by mass or more, 80% by mass or more, 85% by mass or more, and 90% by mass or more in order of preference. The upper limit of the content of component (A) in the oil agent is 100% by mass.

Oils other than component (A) include hydrocarbon oils such as isododecane, isohexadecane, light isoparaffin, liquid paraffin, squalane, squalene, α-olefin oligomer, polybutene, liquid isoparaffin, heavy liquid isoparaffin, polyisobutylene, and hydrogenated polyisobutene; fatty acids such as oleic acid and isostearic acid; higher alcohols such as oleyl alcohol, 2-octyldodecanol, 2-decyltetradecanol, isostearyl alcohol, and 2-hexyldecanol; dimethylpolysiloxane (dimethicone), methyltrimethicone, methylphenylpolysiloxane, and methylphenylpolysiloxane. silicone oils such as perfluoropolyether, perfluorodecamethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexanesiloxane, tetramethyltetrahydrogencyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethyltetratrifluoropropylcyclotetrasiloxane, pentamethylpentatrifluoropropylcyclopentasiloxane, polyether-modified methylpolysiloxane, oleyl-modified methylpolysiloxane, and polyvinylpyrrolidone-modified methylpolysiloxane; Fluorine-based oils such as lanolin acetate, isopropyl lanolinate, and lanolin alcohol; liquid oils that are liquid at 25°C, such as fragrances; cacao butter, shea butter, castor oil, hydrogenated castor oil, hydrogenated coconut oil, petrolatum, hydrogenated castor oil monostearate, hydrogenated castor oil monohydroxystearate, cholesteryl hydroxystearate, dipentaerythritol fatty acid ester, N-lauroyl-L-glutamic acid-di(octyldodecyl/cholesteryl/behenyl), N-lauroyl-L-glutamic acid-di(octyldodecyl/phytosteryl/ behenyl), phytosteryl macadamia nut oil fatty acid, dimer dilinoleic acid (phytosteryl/isostearyl/cetyl/stearyl/behenyl), and other paste-like oils; and solid oils that are solid at 25°C, such as paraffin wax, ceresin wax, microcrystalline wax, polyethylene wax, Fischer-Tropsch wax, stearic acid, behenic acid, cetyl palmitate, polyethylene glycol distearate, glyceryl tribehenate, cholesterol, phytosterol, stearyl-modified polysiloxane, hardened oil, petrolatum, and palm oil.

In addition, when considering emulsion stability, it is preferable that the content of hydrocarbon oil is as small as possible. For example, the content of hydrocarbon oil in the oil-in-water emulsion composition is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and preferably none (0% by mass).

The amount of component (A) in the oil-in-water emulsion composition is preferably 0.5% by mass or more, and more preferably exceeds 1% by mass, from the viewpoint of adjusting the feel, such as imparting a glossy feel. In addition, it is desirable to incorporate as much oil as possible from the viewpoint of adjusting the feel, but it is difficult to incorporate a large amount from the viewpoint of emulsion stability. According to this embodiment, emulsion stability is maintained even in the region where the amount of component (A) is high, that is, where the amount of component (A) exceeds 3% by mass. From this viewpoint, the amount of component (A) in the oil-in-water emulsion composition is preferably more than 3% by mass, and more preferably 4% by mass or more. In addition, the amount of component (A) in the oil-in-water emulsion composition is preferably less than 20% by mass, and more preferably 15% by mass or less, from the viewpoint of emulsion stability.

(Component (B): Polyoxyethylene hydrogenated castor oil having an average number of moles of ethylene oxide added of 20 to 30)
Polyoxyethylene hydrogenated castor oil is a product of adding ethylene oxide to hydrogenated castor oil. The average number of moles of ethylene oxide added is 20 to 30, and more preferably, the average number of moles of ethylene oxide added is 20.

The content of component (B) is appropriately set depending on the balance of the blending amounts of components (A) and (C), but from the viewpoint of emulsion stability, it is preferably 1% by mass or more in the oil-in-water emulsion composition, more preferably 2% by mass or more, and from the viewpoint of stability over time, it is even more preferable that it exceeds 2.5% by mass. Furthermore, from the viewpoint that blending a large amount of component (B) affects the feeling of use, it is preferably 15% by mass or less in the oil-in-water emulsion composition, more preferably 10% by mass or less.

(Component (C): One or more selected from sorbitan monoisostearate and sorbitan diisostearate)
Sorbitan mono- and/or diisostearate are esters of sorbitol and isostearic acid.

Sorbitan monoisostearate and sorbitan diisostearate may be used in combination. For example, the ingredient name "sorbitan sesquiisostearate" in cosmetics is a mixture of sorbitan monoisostearate and sorbitan diisostearate, and therefore sorbitan sesquiisostearate may be used as component (C).

The content of component (C) is not particularly limited, but is preferably 0.1% by mass or more in the oil-in-water emulsion composition, and more preferably exceeds 0.5% by mass since stability over time is further ensured. In addition, the content of component (C) is not particularly limited, but is more preferably 3% by mass or less in the oil-in-water emulsion composition since it affects emulsion stability and stability over time.

The content ratio of component (B) to component (C) ((B)/(C)) is greater than 1 and less than 20 (1 < (B)/(C) (content mass ratio) < 20). When (B)/(C) is in this range, the emulsion stability of the oil-in-water emulsion composition is ensured. It is preferable that (B)/(C) is 2 or more and 10 or less.

The oil-in-water emulsion composition of the present application may contain other surfactants as long as they do not inhibit the effects of the present application. However, in consideration of emulsifiability and stability over time, it is preferable that the composition does not substantially contain other surfactants. "Not containing other surfactants" means that the content of other surfactants is acceptable to the extent of impurities. For example, the content of other surfactants is preferably 0.01% by mass or less, more preferably 0.005% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0% by mass, relative to the oil-in-water emulsion composition.

The mass ratio ((B)+(C))/(A) of the total amount of components (B) and (C) to component (A) is preferably 0.1 or more, and more preferably 0.5 or more, from the viewpoint of emulsion stability. The ratio ((B)+(C))/(A) is preferably 20 or less, and more preferably 15 or less, because this allows the cosmetic effects of the oil, such as a glossy feel, to be optimally exhibited.

(Component (D): Water)
The present embodiment is an oil-in-water emulsion composition, which contains water. The water is used as a dispersion medium, and is not particularly limited, but examples thereof include purified water, distilled water, ion-exchanged water, tap water, hot spring water, and deep sea water.

The content of component (D) is not particularly limited, but is preferably 50 to 95% by mass in the oil-in-water emulsion composition.

In addition to the above-mentioned essential components, other additives may be added to the oil-in-water emulsion composition of the present invention. Examples of other additives include water-soluble polymers, lower alcohols, polyhydric alcohols, amino acids, preservatives, chelating agents, and cosmetic ingredients, which may be appropriately contained within a range that does not impair the effects of the present invention.

The oil-in-water emulsion composition of this embodiment is preferably an oil-in-water emulsion composition for cosmetics because it has the effect of imparting a high gloss feeling.

The oil-in-water emulsion composition of this embodiment may be used as it is as a final cosmetic product, or may be mixed with other ingredients to produce a cosmetic product. That is, the second embodiment is a cosmetic product containing the oil-in-water emulsion composition of the first embodiment. The cosmetic product of the second embodiment is likely to exhibit the effects of the oil-in-water emulsion composition, such as imparting high gloss, emulsification, and improving stability over time. In addition, it is preferable that the cosmetic product is also oil-in-water type. Examples of the oil-in-water emulsion cosmetic product include a form in which an aqueous additive is added to the oil-in-water emulsion composition of the first embodiment to produce an oil-in-water emulsion cosmetic product (a cosmetic product containing the oil-in-water emulsion composition of the first embodiment and an aqueous additive), and a form in which another oil-in-water emulsion composition is added to the oil-in-water emulsion composition of the first embodiment to produce an oil-in-water emulsion cosmetic product.

Examples of cosmetics include lotions, emulsions, creams, beauty essences, massage cosmetics, pack cosmetics, hand creams, body lotions, body creams, makeup cosmetics, makeup base cosmetics, eye creams, sunscreens, hair creams, hair waxes, and other cosmetics. Among these, skin care cosmetics such as lotions, emulsions, creams, beauty essences, massage cosmetics, pack cosmetics, hand creams, body lotions, and body creams are preferred. Methods of use include using the cosmetics on hands, fingers, or cotton, or impregnating nonwoven fabrics, etc. The properties of the cosmetics include liquid, gel, emulsion, cream, semi-solid, and solid forms.

The content of the oil-in-water emulsion composition in the cosmetic is, for example, 10 to 100% by mass.

Other ingredients (particularly water-based additives) that are added to cosmetics include water, water-soluble polymers, preservatives, antioxidants, alcohols, beauty ingredients, etc.

Examples of water-soluble polymers include carrageenan, xanthan gum, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, carboxyvinyl polymer, alkyl-modified carboxyvinyl polymer, polyvinyl alcohol, polyvinylpyrrolidone, (sodium acrylate/sodium acryloyldimethyltaurate) copolymer, (PEG-240/decyltetradeceth-20/HDI) copolymer, etc.

Note that in cosmetics, components (A), (B), and (C) constituting the oil-in-water emulsion composition may not be contained except in the emulsion composition. In this case, the preferred mass ratios of each component (mass ratio of component (B) to component (C) ((B)/(C)), and mass ratio of the total amount of components (B) and (C) to component (A) (((B)+(C))/(A)) described in the section on the oil-in-water emulsion composition above are also applicable to cosmetics.

(Production method)
The method for producing the oil-in-water emulsion composition of this embodiment is not particularly limited as long as it is a known emulsification method, and can be produced. Specifically, the dispersion emulsification method, the phase inversion emulsification method, the phase inversion temperature emulsification method, etc. can be mentioned. Since an emulsion with small emulsion droplets can be obtained, it is preferable to produce it by the phase inversion temperature emulsification method. In the phase inversion temperature emulsification method, the emulsification is performed at a temperature exceeding the phase inversion temperature (PIT) (the temperature at which the hydrophilic and lipophilic properties of the emulsifier (s) reach equilibrium), and when passing through the phase inversion temperature, the interfacial tension is reduced, and fine emulsification is possible without applying strong mechanical force. If the amount of oil is increased to a certain extent, the phase inversion temperature increases, and the particle size of the emulsion droplets tends to increase. In this embodiment, the combination of component (B) and component (C) serves as an emulsification aid to reduce the phase inversion temperature of ester oil, etc., and also contributes to reducing the interfacial tension of the emulsion droplets containing ester oil, etc., and is considered to obtain a fine and stable emulsion. A more specific example of a preferred production method is a production method in which components (A), (B), and (C) and, in some cases, other oily components are heated and mixed, then heated to a temperature equal to or higher than the phase inversion temperature, heated component (D) is added and mixed to emulsify, and then cooling is performed. Various aqueous additives may be added to and mixed with the oil-in-water emulsion composition thus obtained to prepare a cosmetic preparation.

The effects of the present invention will be explained using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Furthermore, unless otherwise specified, each operation is performed at room temperature (20-25°C). In the examples, the indications "parts" or "%" may be used, but unless otherwise specified, they represent "parts by mass" or "% by mass".

Examples 1 to 17 and Comparative Examples 1 to 10: Oil-in-water emulsion composition (lotion)
Oil-in-water emulsion compositions having the formulations shown in Table 1 below were prepared, and the average particle size, gloss, emulsion stability, and stability over time were evaluated by the methods described below. The results are also shown in Table 1.

(Production method)
Components (1) to (18) were heated to about 80° C. and mixed uniformly.

B. Component (19) heated to approximately 80°C was added to A, emulsified, and then cooled to obtain an oil-in-water emulsion composition (lotion).

All of the obtained oil-in-water emulsion compositions were liquid at 25°C.

(Evaluation Method 1: Average Particle Size)
The average particle size was measured by filling each sample into a plastic cuvette UVette 220-1600 nm (manufactured by Eppendorf) and using a real-time nanoparticle size measuring device DelsaMax CORE (manufactured by Beckman Coulter, Inc.).

(Evaluation method 2: Glossiness)
Regarding the glossiness, a use test was conducted by a panel of 20 cosmetic evaluation specialists, who applied 1.5 g of each sample to the entire face, and each panelist immediately evaluated and scored the glossiness on a 5-point scale using the absolute evaluation below. The average score of each sample was calculated from the total score of all the panelists, and the results were judged according to the following 4-point evaluation criteria. If it is ◯ or higher, it is acceptable for practical use.

Absolute evaluation criteria (score): (Evaluation)
5: Very sensitive 4: Slightly sensitive 3: Average 2: Not sensitive at all 1: Not sensitive 4-level rating scale (Rating): (Average score)
⊚: 4 points or more: very good ◯: 3 points or more but less than 4 points: good △: 2 points or more but less than 3 points: slightly poor ×: 1 point or more but less than 2 points: poor.

(Evaluation method 3: Emulsion stability)
Regarding the initial stability, the emulsion stability immediately after preparation of each sample was evaluated according to the following three-level evaluation criteria.

Three-level judging criteria (Judgment): (Judgment criteria)
⊚: No oil floating is observed and the surface is uniform. △: A small amount of oil floating is observed. ×: Separation of oil is observed.

(Evaluation method 4: Stability over time)
The stability over time was evaluated by storing the samples in a thermostatic chamber at 50° C. or 5° C. for one month, and comparing the samples with those immediately after preparation in terms of the presence or absence of drainage or gelation, according to the following four-level evaluation criteria.

4-level judging criteria (Judgment): (Judgment criteria)
◎: No change ○: Very slight change △: Some change ×: Significant change

As is clear from the results in Table 1, the oil-in-water emulsion compositions of Examples 1 to 17 of the present invention had a high gloss immediately after application and were also superior in emulsion stability compared to the oil-in-water emulsion compositions of Comparative Examples 1 to 10.

In contrast, in Comparative Examples 1 and 2, where (B)/(C) is 1 or less or 20 or more, satisfactory results were not obtained in terms of emulsion stability and stability over time. In Comparative Examples 3 to 6, where an activator with a different average number of moles of ethylene oxide added to the PEG-20 hydrogenated castor oil of component (B) or other hydrophilic surfactants with high solubilizing ability were used, the particle size was large like in Comparative Example 1, and satisfactory results were not obtained in terms of emulsion stability and stability over time. In Comparative Example 7, where a lipophilic surfactant with high solubilizing ability different from sorbitan monoisostearate and sorbitan diisostearate of component (C) was used, the particle size was large, and satisfactory results were not obtained in terms of emulsion stability and stability over time. Furthermore, in Comparative Examples 8 to 10, where a hydrocarbon oil or silicone oil different from the ester oil of component (A) was used, satisfactory results were not obtained in terms of particle size, emulsion stability, stability over time, or gloss.

Example 18: Lotion (ingredients) (%)
(1) Macadamia nut oil (component (A)) 2
(2) PEG-20 hydrogenated castor oil (component (B)) *4 5
(3) Sorbitan isostearate (component (C)) *5 0.5
(4) Astaxanthin 0.002
(5) Isopropyl methylphenol 0.01
(6) Vitamin E 0.03
(7) Purified water (component (D)) 58.238
(8) Glycerin 5
(9) Dipropylene glycol 5
(10) 1,3-butylene glycol 5
(11) Purified water 5
(12) Ethanol 8
(13) Phenoxyethanol 0.2
(14) Niacinamide 3
(15) Betaine 1
(16) Sodium lactate 1
(17) Polyquaternium-51 *6 0.01
(18) Cyclohexane-1,4-dicarboxylic acid bisethoxydiglycol *7
1
(19) Alcaligenes-producing polysaccharide *8 0.01
*6 LIPIDURE PMB (BG) (manufactured by NOF Corporation)
*7 NEOSOLUE-AQULIO (manufactured by Nippon Fine Chemicals)
*8 Alcasealan (manufactured by Hakutosha).

(Production method)
A. Components (1) to (6) were heated to about 80° C. and mixed uniformly.
B. (7) heated to about 80° C. was added to A, emulsified, and then cooled to obtain an oil-in-water emulsion composition. The oil-in-water emulsion composition was liquid at 25° C., had a particle size of 300 nm or less, and had excellent emulsion stability and stability over time.
C. Mix ingredients (8) to (19) into B.
D. C was filled into a container to obtain a lotion.

The lotion obtained in this manner provided a high level of lustre immediately after application to the skin, and also had excellent emulsion stability and stability over time.

The (B)/(C) (mass ratio) was 10, and the ((B)+(C))/(A) (mass ratio) was 2.75.

Example 19: Sheet-type cosmetic preparation (ingredients) (%)
(1) Olive oil (component (A)) 1
(2) PEG-20 hydrogenated castor oil (component (B)) *4 2
(3) Sorbitan isostearate (component (C)) 0.4
(4) Cholesterol: 0.01
(5) Ceramide 3 0.01
(6) Vitamin E 0.01
(7) Purified water (component (D)) 67.08
(8) Glycerin 5
(9) 1,3-butylene glycol 10
(10) Methyl parahydroxybenzoate 0.1
(11) Purified water 3
(12) Ethanol 5
(13) Ascorbic acid glucoside 3
(14) Arbutin 1
(15) Sodium lactate 2
(16) Polyacrylate phosphorylcholine glycol *9 0.01
(17) Sodium hydroxide 0.13
(18) Sodium monohydrogen phosphate 0.1
(19) Sodium dihydrogen phosphate 0.1
(20) Xanthan gum 0.05
*9 LIPIDURE HM-600 (manufactured by NOF Corporation).

(Production method)
A. Components (1) to (6) were heated to about 80° C. and mixed uniformly.
B. (7) heated to about 80° C. was added to A, emulsified, and then cooled to obtain an oil-in-water emulsion composition. The oil-in-water emulsion composition was liquid at 25° C., had a particle size of 300 nm or less, and had excellent emulsion stability and stability over time.
C. Mix (8) to (20) with B and impregnate the nonwoven fabric with the mixture.
D. C was sealed and packed in an aluminum laminate bag-shaped container to obtain a sheet-shaped cosmetic preparation.

The sheet-like cosmetic product obtained in this manner was applied to the face, and after 10 minutes it was removed and evaluated. Immediately after application, a high level of shine was observed.

The (B)/(C) (mass ratio) was 5, and the ((B)+(C))/(A) (mass ratio) was 2.4.

Example 20: Cosmetic Serum (ingredients) (%)
(1) Meadowfoam oil (component (A)) 3
(2) PEG-50 hydrogenated castor oil isostearate (component (B)) 8
(3) Sorbitan monoisostearate (component (C)) 1
(4) Hydrogenated polyisobutene *10 1
(5) Fragrance 0.05
(6) Purified water (component (D)) 68.04
(7) Glycerin 6
(8) Diglycerin 1
(9) 1,3-butylene glycol 5
(10) Ethanol 6
(11) Phenoxyethanol 0.3
(12) Sodium hydroxide 0.15
(13) Hyaluronic acid 0.01
(14) Hydrolyzed collagen 0.01
(15) edetate sodium 0.02
(16) Sodium carboxymethylcellulose 0.1
(17) Acrylic acid / alkyl methacrylate copolymer 0.2
(18) Carboxyvinyl polymer 0.12
*10 Pearleem 46 (manufactured by NOF Corporation).

(Production method)
A. Components (1) to (5) were heated to about 80° C. and mixed uniformly.
B. Component (6) heated to about 80°C was added to A, emulsified, and then cooled to obtain an oil-in-water emulsion composition. The oil-in-water emulsion composition was liquid at 25°C, had a particle size of 300 nm or less, and had excellent emulsion stability and stability over time.
C. Components (7) to (18) were mixed with the oil-in-water emulsion composition obtained in B.
D. C was filled into a container to obtain a cosmetic preparation (serum).

The serum obtained in this manner had a high glossy feel immediately after application to the skin, and also had excellent emulsion stability and stability over time.

The (B)/(C) (mass ratio) was 8, and the ((B)+(C))/(A) (mass ratio) was 3.

Claims (7)

The following components (A) to (D):
(A) at least one oil selected from the group consisting of ester oils that are liquid at 25° C. and vegetable oils that are liquid at 25° C.;
(B) polyoxyethylene hydrogenated castor oil having an average number of moles of ethylene oxide added of 20 to 30;
(C) one or more selected from sorbitan monoisostearate and sorbitan diisostearate,
(D) water,
the content mass ratio (B)/(C) of the component (B) to the component (C) is greater than 1 and less than 20;
An oil-in-water emulsion composition, wherein the average particle size of the emulsion particles is 300 nm or less. The oil-in-water emulsion composition according to claim 1, wherein the content of component (A) is 60% by mass or more relative to the oil agent. The oil-in-water emulsion composition according to claim 1 or 2, which is liquid at 25°C. The oil-in-water emulsion composition according to any one of claims 1 to 3, wherein the component (A) is at least one selected from the group consisting of ester oils and vegetable oils having a molecular weight of 400 or more. The oil-in-water emulsion composition according to any one of claims 1 to 4, wherein the content of component (B) is more than 2.5% by mass relative to the oil-in-water emulsion composition. The oil-in-water emulsion composition according to any one of claims 1 to 5, wherein the content of component (C) is more than 0.5% by mass based on the oil-in-water emulsion composition. A cosmetic comprising the oil-in-water emulsion composition according to any one of claims 1 to 6.