WO2022234737A1

WO2022234737A1 - Oil-in-water-type emulsified cosmetic material

Info

Publication number: WO2022234737A1
Application number: PCT/JP2022/013232
Authority: WO
Inventors: 啓渡辺; 允人宇山; マチユバンクトウー; 治男島田; 祐仁伊東
Original assignee: 株式会社資生堂
Priority date: 2021-05-06
Filing date: 2022-03-22
Publication date: 2022-11-10
Also published as: JPWO2022234737A1; CN117120019A

Abstract

Provided is an oil-in-water-type emulsified cosmetic material that is prepared by using a new emulsifier and that has excellent emulsification stability.　An oil-in-water-type emulsified cosmetic material according to the present disclosure contains: a dispersion medium containing water; and oil droplets dispersed in the dispersion medium. The oil droplets each include an oil content and a disk-like structure. The disk-like structures are formed by layering monomolecular films each having a hydrophilic part and a lipophilic part, and are disposed at interfaces of the oil droplets with respect to the aqueous phase.

Description

Oil-in-water emulsified cosmetic

The present disclosure relates to oil-in-water emulsified cosmetics.

Generally, oil-in-water emulsion compositions that can be used in cosmetics are prepared using emulsifiers. In recent years, various emulsifiers have been developed in order to obtain oil-in-water emulsion compositions with excellent emulsion stability.

Patent Document 1 discloses an oil-in-water emulsified composition prepared using an emulsifying dispersant whose main component is a closed endoplasmic reticulum (vesicle) formed by an amphiphilic substance with self-organizing ability.

JP 2006-239666 A

In the field of oil-in-water emulsified cosmetics, in addition to emulsifiers (surfactants), various materials such as oils, thickeners, and moisturizers are used. In oil-in-water emulsified cosmetics, it has been desired to increase the variety of emulsifiers so that such materials can be used as appropriate.

Therefore, the subject of the present disclosure is to provide an oil-in-water emulsified cosmetic prepared using a novel emulsifier and having excellent emulsion stability.

<Aspect 1>
a dispersion medium containing water, and oil droplets dispersed in the dispersion medium;
An oil-in-water emulsified cosmetic comprising
The oil droplets contain oil and a disc-shaped structure,
The disk-shaped structure is formed by laminating monomolecular films having a hydrophilic portion and a lipophilic portion, and is arranged at the interface between the oil droplet and the aqueous phase.
Oil-in-water emulsified cosmetic.
<Aspect 2>
The cosmetic according to aspect 1, wherein the disc-shaped structure is formed of at least one polyglycerin fatty acid ester having an OH/C ratio of 0.30 to 0.80.
<Aspect 3>
The cosmetic according to aspect 1, wherein the disc-shaped structure is formed of at least one polyglycerin fatty acid ester having an OH/C ratio of 0.30 to 0.60.
<Aspect 4>
4. The cosmetic according to any one of aspects 1 to 3, wherein the maximum length of one side of the cross-sectional shape of the disc-shaped structure is 500 nm or less.
<Aspect 5>
The cosmetic according to any one of aspects 1 to 4, wherein the oil content is 40% by mass or less.
<Aspect 6>
The cosmetic according to any one of aspects 2 to 5, wherein the number of carbon atoms in the fatty acid portion of the polyglycerol fatty acid ester is 12 or more and 17 or less.
<Aspect 7>
7. The cosmetic according to any one of aspects 2 to 6, wherein the polyglycerin part of the polyglycerin fatty acid ester is composed of polyglycerin having a tetramer or more and an octamer or less.
<Aspect 8>
The cosmetic according to any one of aspects 1 to 7, wherein the oil is at least one selected from the group consisting of polar oils and silicone oils.

According to the present disclosure, it is possible to provide an oil-in-water emulsified cosmetic prepared using a novel emulsifier and having excellent emulsion stability.

FIG. 2 is a schematic diagram showing the state of arrangement of disk-shaped structures at the interface between oil droplets and the aqueous phase of the oil-in-water emulsified cosmetic according to one embodiment of the present disclosure.

The embodiments of the present disclosure will be described in detail below. The present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the spirit of the invention.

The oil-in-water emulsified cosmetic of the present disclosure includes a dispersion medium containing water and oil droplets dispersed in the dispersion medium, the oil droplets including oil and disk-shaped structures, and the disk-shaped structures are , a monomolecular film having a hydrophilic portion and a lipophilic portion are laminated to each other and arranged at the interface between the oil droplet and the water phase.

Although not limited by the principle, in the oil-in-water emulsified cosmetic of the present disclosure, the disc-shaped structure functions as an emulsifier, and the principle of action for obtaining an oil-in-water emulsified cosmetic with excellent emulsion stability is as follows. I think that it is as follows.

As shown in FIG. 1, the disc-shaped structure of the present disclosure is composed of two vesicles formed by vesicles formed in the aqueous phase, for example, collapsing under the influence of oil in the cosmetic. After a part of the monomolecular film of the molecular film adsorbs to the surface of the oil via the lipophilic part (hydrophobic part), the bilayer membrane that constitutes the vesicle via the hydrophilic part of the monomolecular film or the monomolecular membranes forming the bilayer membrane of the vesicle are laminated with the hydrophilic portions interposed therebetween or with the lipophilic portions interposed therebetween. Thus, the disc-shaped structure is formed of a monomolecular film having a hydrophilic portion and a lipophilic portion that constitute the bilayer of the vesicle. As a result, in the laminate of disk-shaped structures, the lipophilic portion (hydrophobic portion) is arranged at the interface with the oil droplets, and the hydrophilic portion is arranged at the interface with the water phase, so that the laminate as a whole is similar to an emulsifier. I think it can work.

A monomolecular film having a hydrophilic portion and a lipophilic portion itself has the ability to emulsify oil. Therefore, when this monomolecular film material is used as an emulsifier to emulsify water and oil, the monomolecular film material does not stack in a layered manner, and the oil droplets and the aqueous phase are not laminated in the same way as common emulsifiers. is thought to be oriented near the interface of Under such conditions, the material of the monolayer generally does not remain near the interface with the aqueous phase in the oil droplets (emulsified particles), e.g., in the aqueous phase or at the interface of other adjacent oil droplets. is considered to be in an equilibrium state in which the As a result, the oil is exposed at the interface of the oil droplets, and tends to aggregate and coalesce with the oil in other adjacent oil droplets, which is likely to reduce the emulsion stability.

On the other hand, in the oil-in-water emulsified cosmetic of the present disclosure, a monomolecular film having a hydrophilic portion and a lipophilic portion is arranged in the form of a disk-shaped structure laminated in layers at the interface between the oil droplets and the aqueous phase. there is Similar to vesicles, this disc-shaped structure is thought to have reduced or suppressed migration in the aqueous phase or at the interface of other adjacent oil droplets, compared to common emulsifiers. As a result, the oil is less likely to be exposed at the interface of the oil droplets and less likely to aggregate and coalesce with the oil in other adjacent oil droplets, thus improving the emulsification stability.

In addition, the oil-in-water emulsified cosmetic containing the disc-shaped structure of the present disclosure can also improve the occlusion effect (the effect of preventing moisture from escaping from the skin) as an incidental effect. This is because when the cosmetic of the present disclosure is applied to the skin, the disc-shaped structures in the cosmetic are arranged so as to cover the skin surface, so evaporation of moisture from the skin can be reduced or prevented. I think it's for the sake of

In addition, the oil-in-water emulsified cosmetic containing the disk-shaped structure of the present disclosure can improve permeation feeling, moist feeling, usability (stickiness resistance), film resistance feeling, etc. as additional effects. .

The emulsifying dispersant described in Patent Document 1 uses the vesicle itself, which is a closed endoplasmic reticulum, as an emulsifier, and is different from the disc-shaped structure in the present disclosure.

The definitions of terms in this disclosure are as follows.

In the present disclosure, the term “disc-shaped structure” does not form a closed endoplasmic reticulum structure like a vesicle, and the cross-sectional shape of such a structure is substantially plate-shaped as shown in FIG. (eg, generally square, generally rectangular) are contemplated. Here, the term “substantially” means that the cross-sectional shape of such a structure is not allowed to be spherical like a vesicle, but is deformed to some extent, for example, deformed so as to exhibit a curvature along the shape of an oil droplet. is intended to be acceptable.

"Vesicles" in the present disclosure also include liposomes and polymersomes.

《Oil-in-water emulsified cosmetic》
<Dispersion medium>
The dispersion medium (aqueous phase) in the oil-in-water emulsified cosmetic of the present disclosure (sometimes simply referred to as “cosmetics”) contains water.

(water)
The amount of water to be blended is not particularly limited, and for example, from the viewpoint of emulsion stability, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, and 60% by mass of the total amount of the cosmetic. 70% by mass or more, or 80% by mass or more, and 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less .

The water that can be used in the oil-in-water emulsified cosmetic of the present disclosure is not particularly limited, and for example, water used in cosmetics and quasi-drugs can be used. For example, deionized water, distilled water, ultrapure water, and tap water can be used.

<Oil droplet>
The oil droplets as the oil phase or dispersed phase in the oil-in-water emulsified cosmetic of the present disclosure contain an oil component and a disc-shaped structure.

This disc-shaped structure is a novel emulsifier and can improve the emulsification stability of oil droplets in oil-in-water emulsified cosmetics. Therefore, in some embodiments, the average particle size of the oil droplets can be, for example, 10 μm or less, 7 μm or less, 5 μm or less, or 3 μm or less immediately after production. Although the lower limit of the average particle diameter is not particularly limited, it can be, for example, 500 nm or more, 700 nm or more, or 1 μm or more. Here, the average particle diameter of the oil droplets can be defined as the average value of the projected area circle equivalent diameters of 10 or more, preferably 100 or more oil droplets observed with an optical microscope.

(oil content)
The oil content in the oil-in-water emulsion cosmetic of the present disclosure is 1.0% by mass or more, 2.0% by mass or more, 3.0% by mass or more, and 5.0% by mass with respect to the total amount of the cosmetic. 7.0% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more, and 50% by mass or less, 45% by mass or more 40% by mass or less, 35% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less. The oil content is preferably 45% by mass or less, more preferably 40% by mass or less, relative to the total amount of the cosmetic, from the viewpoint of emulsion stability and the like.

Since the disc-shaped structure of the present disclosure can function as an emulsifier for various oils, there are no particular restrictions on the type of oil. As oils, for example, volatile and non-volatile oils can be used. An oil component can be used individually or in combination of 2 or more types. Here, "volatile" is intended to exhibit a volatile content of more than 5% when left at 105°C under atmospheric pressure for 3 hours. The volatile content, which is a guideline for volatility, can be 10% or more, 20% or more, 40% or more, 50% or more, 60% or more, 80% or more, or 100%. Alternatively, the boiling point at 1 atmosphere (101.325 kPa) can be used as an indicator of volatility. The boiling point can be 250° C. or lower, 240° C. or lower, or 230° C. or lower, and can be 80° C. or higher, 100° C. or higher, 120° C. or higher, 150° C. or higher, or 160° C. or higher. In addition, in the present disclosure, "non-volatile" intends to exhibit a volatile content of 5% or less when left at 105°C for 3 hours.

The volatile oil is not particularly limited, and examples include volatile silicone oil and volatile hydrocarbon oil. Among these, volatile silicone oils are preferable from the viewpoint of reducing the average particle size of oil droplets. A volatile oil can be used individually or in combination of 2 or more types.

Volatile silicone oils include, for example, volatile acyclic silicone oils and volatile cyclic silicone oils.

As volatile acyclic silicone oils, for example, volatile linear silicone oils and volatile branched silicone oils can be used.

Volatile linear silicone oils include, for example, dimethylpolysiloxane with a viscosity of 0.65 cs (sometimes referred to as "dimethicone"), dimethylpolysiloxane with a viscosity of 1 cs, dimethylpolysiloxane with a viscosity of 1.5 cs, and dimethylpolysiloxane with a viscosity of 2 cs. and low-molecular-weight linear dimethylpolysiloxane such as dimethylpolysiloxane. Among them, dimethylpolysiloxane having a viscosity of 2 cs is more preferable from the viewpoint of reducing the average particle size of oil droplets. Here, these viscosities are intended to be kinematic viscosities at 25°C.

Volatile branched silicone oils include, for example, low-molecular-weight branched siloxanes such as methyltrimethicone, tris(trimethylsilyl)methylsilane, and tetrakis(trimethylsilyl)silane.

Volatile cyclic silicone oils include, for example, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane.

Volatile hydrocarbon oils include, for example, heptane, isododecane, isohexadecane, and isodecane.

In addition to the above-mentioned volatile oils, examples of oils include oils commonly used in cosmetics, such as liquid oils, solid oils, waxes, hydrocarbon oils other than those mentioned above, silicone oils other than those mentioned above, and polar oils. can be done. Among these, silicone oil is preferable from the viewpoint of reducing the average particle size of oil droplets. Here, some UV absorbers act as oils, especially polar oils. Such ultraviolet absorbers can also be regarded as oils.

Examples of liquid oils include avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, sasanqua oil, castor oil, and linseed oil. , safflower oil, cottonseed oil, perilla oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, sinagi oil, Japanese pear oil, jojoba oil, germ oil, and triglycerin.

Examples of solid fats and oils include cacao butter, coconut oil, horse fat, hydrogenated coconut oil, palm oil, beef tallow, mutton tallow, hydrogenated beef tallow, palm kernel oil, lard, beef bone fat, Japanese wax kernel oil, hydrogenated oil, beef Leg fat, Japanese wax, and hydrogenated castor oil.

Waxes include, for example, beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, wart wax, whale wax, montan wax, bran wax, lanolin, kapok wax, lanolin acetate, liquid lanolin, sugarcane wax, isopropyl lanolin fatty acid, hexyl laurate, Reduced lanolin, jojoba wax, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, and POE hydrogenated lanolin alcohol ether.

Examples of hydrocarbon oils include liquid paraffin, ozokerite, squalane, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax, and olefin oligomers. Among them, squalane is preferable from the viewpoint of emulsion stability.

Examples of silicone oils include linear silicones such as dimethylpolysiloxane (dimethicone), methylphenylpolysiloxane (diphenylsiloxyphenyltrimethicone), and methylhydrogenpolysiloxane having a viscosity of 6 cs or more.

As the polar oil, for example, a polar oil with an IOB of 0.10 or more can be used. Examples of such polar oils include isopropyl myristate (IOB value = 0.18), octyl palmitate (IOB value = 0.13), isopropyl palmitate (IOB value = 0.16), butyl stearate ( IOB value = 0.14), hexyl laurate (IOB value = 0.17), myristyl myristate (IOB value = 0.11), decyl oleate (IOB value = 0.11), isononyl isononanoate (IOB value = 0.20), isotridecyl isononanoate (IOB value = 0.15), cetyl ethylhexanoate (IOB value = 0.13), pentaerythrityl tetraethylhexanoate (IOB value = 0.35), diethylhexyl succinate (IOB value = 0.32), dioctyl succinate (IOB value = 0.36), glycol distearate (IOB value = 0.16), glyceryl diisostearate (IOB value = 0.29), neopentyl glycol dicaprate. (IOB value = 0.25), diisostearyl malate (IOB value = 0.28), trimethylolpropane triisostearate (IOB value = 0.16), glyceryl tri-2-ethylhexanoate (triethylhexanoin) (IOB value = 0.35), trimethylolpropane trioctanoate (IOB value = 0.33), trimethylolpropane triisostearate (IOB value = 0.16), diisobutyl adipate (IOB value = 0.46), N-lauroyl-L-glutamic acid-2-octyldodecyl ester (IOB value = 0.29), 2-hexyldecyl adipate (IOB value = 0.16), diisopropyl sebacate (IOB value = 0.40), methoxy Ethylhexyl cinnamate (IOB value = 0.28), 2-ethylhexyl palmitate (IOB value = 0.13), 2-ethylhexyl ethylhexanoate (IOB value = 0.2), triisostearin (IOB value = 0.16 ), PPG-3 dipivalate (IOB value=0.52), and tri(caprylic/capric)glyceryl (IOB value=0.33). Among them, pentaerythrityl tetraethylhexanoate (IOB value=0.35) is preferable from the viewpoint of emulsion stability.

Examples of UV absorbers that can be regarded as oils include UV absorbers with an IOB of 0.10 or more, specifically ethylhexyl methoxycinnamate, octocrylene, polysilicone-15, t-butylmethoxydibenzoylmethane. , ethylhexyltriazon, bisethylhexyloxyphenolmethoxyphenyltriazine, hexyl diethylaminohydroxybenzoylbenzoate, oxybenzone-3, methylenebisbenzotriazolyltetramethylbutylphenol, homosalate, and ethylhexyl salicylate. be able to. A ultraviolet absorber can be used individually or in combination of 2 or more types.

The IOB value of the polar oil and UV absorber can be, for example, 0.11 or more, 0.12 or more, or 0.13 or more, and 0.50 or less, 0.45 or less, or 0.40 or less. can be Here, the IOB value is an abbreviation for Inorganic/Organic Balance (inorganic/organic ratio), which is a value representing the ratio of the inorganic value to the organic value, and is an index indicating the degree of polarity of an organic compound. It becomes. The IOB value is specifically expressed as IOB value=inorganic value/organic value. For each of the "inorganicity value" and the "organicity value", various The "inorganic value" and "organic value" are set according to the atom or functional group, and the "inorganic value" and "organic value" of all atoms and functional groups in the organic compound are accumulated. (See, for example, Yoshio Koda, "Organic Conceptual Diagram-Basics and Applications-", pp. 11-17, Sankyo Publishing, 1984).

In some embodiments, among the above-described oils, at least one selected from the group consisting of polar oils and silicone oils is preferred. The polar oil is at least one polyglycerin fatty acid ester having an OH/C ratio of 0.30 to 0.60, preferably 0.35 to 0.60, more preferably 0.40 to 0.60, which will be described later. When used in conjunction with the disc-like structure being formed, the average oil droplet size can be reduced. The use of silicone oil is also advantageous as it can reduce the average particle size of the oil droplets.

(disk-shaped structure)
The disc-shaped structure of the present disclosure, which is a novel emulsifier, is formed by laminating monomolecular films having a hydrophilic portion and a lipophilic portion, and is arranged at the interface between the oil droplet and the aqueous phase. .

From the viewpoint of emulsification performance, the number of laminated monomolecular films can be 3 or more, or 5 or more. The upper limit of the number of layers to be laminated is not particularly limited, and may be, for example, 15 layers or less, 13 layers or less, 11 layers or less, 9 layers or less, or 7 layers or less.

The maximum length of one side of the cross-sectional shape of the disk-shaped structure, for example, the length in the width direction of the disk-shaped structure in FIG. or less, or 30 nm or more, 40 nm or more, or 50 nm or more. Here, when the cross section of the disc-shaped structure is deformed to have a curvature along the shape of the oil droplet, the maximum length is intended to be the length of the curved surface as shown in FIG. .

For example, the presence or absence of a disk-shaped structure and the maximum length of one side of the cross-sectional shape of the disk-shaped structure are determined using a frozen replica transmission electron microscope (TEM, H-7650: manufactured by Hitachi, Ltd.). It can be confirmed or obtained from the photograph. The maximum length of one side of the cross-sectional shape of the disk-shaped structure is the average value of 10 arbitrarily selected disk-shaped structures.

As shown in FIG. 1, the disc-shaped structure is formed by the vesicles in the aqueous phase collapsing, and the monomolecular membrane of the bilayer membrane that constitutes the vesicle is partially replaced by the lipophilic part (hydrophobic part). After being adsorbed on the surface of the oil via the , are considered to be formed by lamination with hydrophilic portions interposed therebetween or oleophilic portions interposed therebetween. That is, the monomolecular film of the disk-like structure is typically composed of at least one kind of surfactant capable of forming vesicles. The presence or absence of vesicles in cosmetics can be determined, for example, by a frozen replica method using a frozen replica transmission electron microscope (TEM, H-7650: manufactured by Hitachi, Ltd.), or by a small-angle X-ray scattering measurement device (SAXSess, Anton Paar) and Zetasizer Nano (Malvern Panalytical).

The amount of the surfactant that constitutes the disk-shaped structure is 0.1% by mass or more and 0.1% by mass or more, based on the total amount of the cosmetic, from the viewpoint of the formability of the disk-shaped structure, emulsion stability, occlusion effect, etc. .3 mass % or more, or 0.5 mass % or more, and 10 mass % or less, 5.0 mass % or less, or 3.0 mass % or less.

In some embodiments, the disc-shaped structure of the present disclosure can highly emulsify oil. The emulsifying ability of the oil can be evaluated by the ratio of the mass of the oil to the mass of the surfactant forming the disk-shaped structure. Such a mass ratio can be, for example, 20 or more, 30 or more, 40 or more, or 50 or more, and can be 90 or less, 85 or less, or 80 or less.

As the surfactant capable of forming the disc-shaped structure, polyglycerin fatty acid esters can be preferably used from the viewpoint of formability of the disc-shaped structure, emulsion stability, and the like. This polyglycerin fatty acid ester is a sustainable material, and as an incidental effect, it can provide a moist feeling when applied to the skin, and can improve the occlusion effect. . Polyglycerol fatty acid esters can be used alone or in combination of two or more.

Polyglycerin fatty acid esters can be prepared by esterifying fatty acids with polyglycerin as shown in the following reaction scheme:

Here, in the polyglycerin fatty acid ester, the portion derived from fatty acids can be called a fatty acid portion, and the portion derived from polyglycerin can be called a polyglycerin portion. The fatty acid portion corresponds to the lipophilic portion, and the polyglycerol portion corresponds to the hydrophilic portion.

The polyglycerol fatty acid ester preferably has a fatty acid moiety with 12 or more, 13 or more, or 14 or more carbon atoms from the viewpoint of disk-shaped structure formability, emulsion stability, occlusion effect, and the like. , 17 or less, 16 or less, or 15 or less.

Fatty acids that can be used when preparing polyglycerol fatty acid esters may be saturated fatty acids or unsaturated fatty acids, and may be linear fatty acids or branched fatty acids. Such fatty acids can include, for example, lauric acid, myristic acid, and palmitic acid. Among them, myristic acid and lauric acid are preferred.

The polyglycerin portion of the polyglycerin fatty acid ester is preferably a trimer or higher or a tetramer or higher from the viewpoint of disk-shaped structure formability, emulsion stability, occlusion effect, etc. Hereinafter, it is preferably an octamer or less, a heptamer or less, or a hexamer or less, and more preferably a tetramer or more and an octamer or less. Here, the numerical value of n of the polyglycerol fatty acid ester in the above reaction formula matches, for example, the numerical value of 2 in the dimer.

The disc-shaped structure is preferably made of at least one polyglycerin fatty acid ester having an OH/C ratio of 0.30 to 0.80. The OH/C ratio is preferably 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, or 0.50 or more, and is 0.80 or less, 0.75 or less, It is preferably 0.70 or less, 0.65 or less, or 0.60 or less. A polyglycerol fatty acid ester having such an OH/C ratio easily forms a disc-shaped structure, and can further improve the emulsion stability, occlusion effect, etc. of the oil-in-water emulsified cosmetic.

Here, the "OH/C ratio" in the present disclosure means the ratio of the number of hydroxyl groups in the polyglycerin portion to the number of carbon atoms in the fatty acid portion, and is a parameter relating to the balance between hydrophilicity and lipophilicity. For example, in the case of polyglyceryl-6 myristate, the number of carbon atoms in the fatty acid portion is 14, and the polyglycerin portion is a hexamer, in which case the number of hydroxyl groups is 7 (=6+1). Therefore, the OH/C ratio is 0.50 (=7/14).

Specific examples of polyglycerol fatty acid esters include polyglyceryl-6 myristate, polyglyceryl-4 laurate, polyglyceryl-5 laurate, polyglyceryl-6 laurate, and polyglyceryl-10 palmitate.

<Optional component>
The oil-in-water emulsified cosmetic composition of the present disclosure can be appropriately blended with various components within a range that does not affect the effects of the present disclosure. Examples of various components include additive components that can be usually blended in cosmetics, such as surfactants other than surfactants that constitute the disk-shaped structure, moisturizing agents, thickeners, water-soluble polymers, and highly oil-soluble ingredients. Molecules, film-forming agents, higher fatty acids, sequestering agents, lower alcohols, higher alcohols, polyhydric alcohols, various extracts, sugars, amino acids, organic amines, polymer emulsions, chelating agents, other than the above UV absorbers UV absorbers, pH adjusters, skin nutrients, vitamins, pharmaceuticals, quasi-drugs, water-soluble agents applicable to cosmetics, buffers, anti-fading agents, preservatives, dispersants, propellants, fillers , pigments, dyes, pigments, fragrances, and the like. Optional components can be blended in the oil phase and/or the water phase, and can be used alone or in combination of two or more.

The disc-shaped structure in the oil-in-water emulsified cosmetic of the present disclosure functions as an emulsifier. Therefore, a surfactant other than the surfactant that constitutes the disc-shaped structure may be blended in the cosmetic, but from the viewpoint of the formability of the disc-shaped structure, the emulsion stability, etc., such a surfactant The amount of the agent is 5.0% by mass or less, 3.0% by mass or less, 1.0% by mass or less, 0.5% by mass or less, or 0.1% by mass or less with respect to the total amount of the cosmetic. is preferred, and it is more preferred not to incorporate such a surfactant.

<Viscosity of cosmetics>
In some embodiments, the oil-in-water emulsified cosmetic composition of the present disclosure has a viscosity of 25 Pa s or less and 23 Pa s or less immediately after preparation of the cosmetic composition as measured using the conditions and apparatus described in the examples below. ·s or less, 20 Pa·s or less, or 19 Pa·s or less, or 1.0 Pa·s or more, 1.5 Pa·s or more, or 2.0 Pa·s or more. Such a viscosity of the cosmetic immediately after preparation can be referred to as "initial viscosity".

<pH of cosmetics>
In some embodiments, the oil-in-water emulsified cosmetic of the present disclosure has a pH of 7.0 or less, 6.8 or less, or 6.0 or less, as measured using the conditions and apparatus described in the examples below. 5 or less. Although the lower limit of the pH of the cosmetic is not particularly limited, it is preferably 5.5 or higher or 6.0 or higher, for example, from the viewpoint of irritation to the skin.

<<Method for preparing oil-in-water emulsified cosmetic>>
The oil-in-water emulsified cosmetic of the present disclosure is not limited to the following method, but can be prepared as follows. Various materials described above can be used in the preparation of cosmetics.

For example, a vesicle solution is formed by mixing a vesicle-forming surfactant such as a polyglycerol fatty acid ester with water optionally containing a water-soluble drug, an aqueous component, and the like. Then, an oil component containing an oil-soluble drug, an oily component, etc. is optionally added to the vesicle solution, and the mixture is stirred and mixed to obtain the oil-in-water emulsified cosmetic composition of the present disclosure.

<<Dosage form of oil-in-water emulsified cosmetic>>
The dosage form of the oil-in-water emulsified cosmetic of the present disclosure is not particularly limited, and examples thereof include liquid, milky lotion, cream, gel, spray, and mousse. Here, in the present disclosure, "spray" can include mist type spray, aerosol type spray, and the like.

<<Uses of oil-in-water emulsified cosmetics>>
The oil-in-water emulsified cosmetic of the present disclosure can be used, for example, as a cosmetic that is spread and applied to the skin, hair, or the like.

The product form of the cosmetics of the present disclosure is not particularly limited, but for example, facial cosmetics such as lotions, beauty essences, milky lotions, and packs; makeup cosmetics such as foundations, lipsticks, and eye shadows; body cosmetics; hair cosmetics such as hair liquids, hair tonics, hair conditioners, shampoos, rinses and hair restorers; and ointments.

The oil-in-water emulsified cosmetic of the present disclosure will be described in more detail below with reference to examples, but the cosmetic of the present disclosure is not limited to these. Hereinafter, unless otherwise specified, the compounding amount is indicated by mass %.

"Evaluation method"
<Evaluation of disc-shaped structure>
The prepared cosmetic was observed with a frozen replica transmission electron microscope (TEM, H-7650: manufactured by Hitachi, Ltd.) using the frozen replica method, and the disc-shaped structure at the interface with the water phase in the oil droplet was observed. Checked for presence. In the table, "yes" indicates that the disc-shaped structure was confirmed, and "no" indicates that it was not. Table 4 also lists the maximum length of the disc-shaped structures observed. The maximum length of the disc-like structure is the average value of ten arbitrarily selected disc-like structures.

<Evaluation of emulsion stability>
The size of the oil droplets within 1 hour after preparation of the cosmetic preparation and the size of the oil droplets after storage at 50°C for 4 weeks were observed with an optical microscope, and the emulsification stability was evaluated according to the following criteria. Here, A and B ratings can be considered pass and C rating fail:
A: Almost no change in oil droplet size.
B: The oil droplet size was slightly increased.
C: The oil droplet size was obviously increased, or the cosmetic was separated.

<Evaluation of particle size of emulsified particles (oil droplets)>
The particle size of the emulsified particles (oil droplets) in the cosmetic is measured by direct visual observation with an optical microscope (BX60, manufactured by OLYMPUS), arbitrarily selecting 10 emulsified particles, and measuring the projected area circle of the emulsified particles. The average equivalent diameter is shown in the table.

<Evaluation of viscosity>
The viscosity immediately after preparation of the cosmetic was evaluated using a B-type viscometer (TVB-type viscometer TVB-10, manufactured by Toki Sangyo Co., Ltd.) under the conditions of rotor number M3, 30° C., and 12 rpm.

<Evaluation of pH>
The pH of the cosmetic was measured using a pH tester (HORIBA pH METER F-51) in an atmosphere of 30°C.

<Evaluation of sense of penetration>
A panel of 10 experts evaluated the permeation feeling when each cosmetic was directly applied to the face according to the following evaluation criteria:
A: 9 to 10 persons answered that they felt that the cosmetics were soaked into the skin.
B: 7 to 8 panelists answered that they felt that the cosmetics were soaked into the skin.
C: 5 to 6 persons answered that they felt that the cosmetic material was soaked into the skin.
D: 3 to 4 persons answered that they felt that the cosmetic material permeated the skin.
E: 0 to 2 persons answered that they felt that the cosmetics were soaked into the skin.

<Evaluation of moist feeling>
10 expert panelists evaluated the moist feeling when each cosmetic was directly applied to the face according to the following evaluation criteria:
A: 9 to 10 persons answered that they felt a moist touch.
B: 7 to 8 persons answered that they felt a moist touch.
C: 5 to 6 persons answered that they felt a moist feeling.
D: 3 to 4 persons answered that they felt a moist touch.
E: 0 to 2 persons answered that they felt a moist feeling.

<Usability evaluation>
10 expert panelists evaluated the usability (stickiness) when each cosmetic was applied directly to the face according to the following evaluation criteria:
A: 0 to 1 persons answered that they felt stickiness.
B: 2 to 3 persons answered that they felt stickiness.
C: 4 to 5 panelists answered that they felt stickiness.
D: 6 to 7 panelists answered that they felt stickiness.
E: 8 to 10 panelists answered that they felt stickiness.

<Evaluation of film feeling>
10 expert panelists evaluated the film feeling when each cosmetic was applied directly to the face according to the following evaluation criteria. Here, the "feeling of a film" is intended to give a sense of discomfort as if a solid film had been formed on the skin:
A: 0 to 1 persons answered that they felt a filmy feeling.
B: 2 to 3 persons answered that they felt a filmy feeling.
C: 4 to 5 panelists answered that they felt a filmy feeling.
D: 6 to 7 panelists answered that they felt a filmy feeling.
E: 8 to 10 panelists answered that they felt a filmy feeling.

<<Test Example 1: Emulsification stability of cosmetic along with formation of disc-shaped structure>>
In Test Example 1, the emulsification stability of cosmetics accompanying the formation of disc-shaped structures was examined. Table 1 shows the results. The emulsification stability of the cosmetics of Comparative Examples 1 and 2 was poor, and thus the particle size, viscosity, and pH of the emulsified particles were not evaluated.

<Method for producing cosmetics>
Using the formulations shown in Table 1, oil-in-water emulsified cosmetics were produced by the following method. Here, the numbers shown below correspond to the numbers on the left side of Table 1 indicating the ingredient names of the formulations.

(Example 1)
No. 1 to No. 5, No. 12 and no. The 13 materials were uniformly mixed to obtain an aqueous phase part containing vesicles.

　No. 11 was added and uniformly dispersed with a dispenser to obtain an oil-in-water emulsified cosmetic of Example 1.

(Examples 2-8 and Comparative Examples 1-2)
Oil-in-water emulsified cosmetics of Examples 2-8 and Comparative Examples 1-2 were obtained in the same manner as in Example 1, except that the formulations shown in Table 1 were changed.

<result>
From the results in Table 1, it was confirmed that the emulsification stability of the cosmetic is improved when the disc-shaped structure is formed at the interface between the oil droplet and the water phase. From this result, it was found that the disc-shaped structure can function as an emulsifier. Moreover, from the results of Examples 7 and 8, it was also found that the disc-shaped structure can highly emulsify oil.

It was also found that when the surfactant is a polyglycerin fatty acid ester, a disc-shaped structure is easily obtained when the OH/C ratio is about 0.30 to 0.80.

<<Test Example 2: Emulsification performance of disc-shaped structure for various oils>>
In Test Example 2, the emulsification performance of the disc-shaped structure for various oil components was examined. The results are shown in Tables 2-3. Tables 2 and 3 also show the results of Examples 3 and 4, respectively.

<Method for producing cosmetics>
(Examples 9 to 21)
Using the formulations shown in Tables 2 and 3, in the same manner as in Example 1, oil-in-water emulsified cosmetics of Examples 9 to 21 were obtained.

<result>
From the results in Tables 2 and 3, it was confirmed that the disc-shaped structure can exhibit emulsification performance for any kind of oil. Among others, it has been found that the combination of disc-shaped structures and silicone oil can reduce the particle size of emulsified particles.

<<Test Example 3: Various performances such as penetration of cosmetics accompanying the formation of the disc-shaped structure>>
In Test Example 3, in addition to the emulsification stability of the cosmetic along with the formation of the disc-shaped structure, penetration feeling, moist feeling, usability (stickiness) and film feeling were examined. Table 4 shows the results.

<Method for producing cosmetics>
(Comparative Examples 3-4 and Examples 22-25)
Using the formulation shown in Table 4, in the same manner as in Example 1, oil-in-water emulsified cosmetics of Comparative Examples 3-4 and Examples 22-25 were obtained.

<result>
From the results in Table 4, when the disc-shaped structure is formed at the interface between the oil droplets and the water phase, the emulsification stability of the cosmetic is improved, and the feeling of penetration, moist feeling, usability (stickiness), and film formation are improved. It was also found that good results were obtained with respect to feeling.

Claims

a dispersion medium containing water, and oil droplets dispersed in the dispersion medium;
An oil-in-water emulsified cosmetic comprising
The oil droplets contain oil and a disc-shaped structure,
The disk-shaped structure is formed by laminating monomolecular films having a hydrophilic portion and a lipophilic portion, and is arranged at the interface between the oil droplet and the aqueous phase.
Oil-in-water emulsified cosmetic.
The cosmetic according to claim 1, wherein the disc-shaped structure is formed from at least one polyglycerin fatty acid ester having an OH/C ratio of 0.30 to 0.80.
The cosmetic according to claim 1, wherein the disc-shaped structure is formed of at least one polyglycerin fatty acid ester having an OH/C ratio of 0.30 to 0.60.
The cosmetic according to any one of claims 1 to 3, wherein the maximum length of one side of the cross-sectional shape of the disc-shaped structure is 500 nm or less.
The cosmetic according to any one of claims 1 to 4, wherein the oil content is 40% by mass or less.
The cosmetic according to any one of claims 2 to 5, wherein the number of carbon atoms in the fatty acid portion of the polyglycerol fatty acid ester is 12 or more and 17 or less.
The cosmetic material according to any one of claims 2 to 6, wherein the polyglycerin part of the polyglycerin fatty acid ester is formed of polyglycerol having a tetramer or more and an octamer or less.
The cosmetic according to any one of claims 1 to 7, wherein the oil is at least one selected from the group consisting of polar oils and silicone oils.