Oil-in-water emulsion cosmetic

Abstract

Provided is a novel oil-in-water emulsion cosmetic that contains a hygroscopic aqueous compound and has excellent usability with an improvement upon problems such as stickiness associated with hygroscopic aqueous compounds.　An oil-in-water emulsion cosmetic according to the present disclosure contains (a) a hygroscopic aqueous compound, (b) a polyglycerin fatty acid ester, (c) an oil component, and (d) water.

Description

Oil-in-water emulsion cosmetics

[0001] The present disclosure relates to an oil-in-water emulsion cosmetic.

[0002] In the field of cosmetics, oil-in-water emulsion cosmetics containing various surfactants, drugs, and the like have been developed.

[0003] Patent Document 1 discloses an oil-in-water emulsion cosmetic comprising (A) a specific cyclic carboxamide derivative or a salt thereof, (B) core-corona type particles, (C) an oil component, and (D) water, wherein the core-corona type particles (B) are particles obtained by radical polymerization of a polyethylene oxide macromonomer and a hydrophobic monomer selected from the group consisting of an acrylic acid / methacrylic acid derivative monomer and an acrylamide / methacrylamide derivative monomer.

[0004] Patent Document 2 discloses an oil-in-water emulsion cosmetic comprising a dispersion medium containing water and oil droplets dispersed in the dispersion medium, wherein the oil droplets contain an oil component and disk-shaped structures, and the disk-shaped structures are formed by stacking monomolecular films each having a hydrophilic portion and a lipophilic portion, and are arranged at the interface between the oil droplets and the aqueous phase.

[0005] Patent Document 3 discloses an oil-in-water emulsion cosmetic that contains (a) a fucose-containing polysaccharide and (b) a moisturizing agent.

[0006] International Publication No. 2023 / 120180 International Publication No. 2022 / 234737 Japanese Patent Application Laid-Open No. 11-269060

[0007] As described in Patent Documents 1 and 3, cosmetics containing hygroscopic aqueous compounds such as cyclic carboxamide derivatives can sometimes cause problems such as stickiness. To improve such problems, Patent Document 1, for example, uses a special material known as a core-corona type particle.

[0008] Therefore, an object of the present disclosure is to provide a novel oil-in-water emulsion cosmetic containing a hygroscopic aqueous compound, which has excellent usability and overcomes the problems associated with hygroscopic aqueous compounds, such as stickiness.

[0009] Aspect 1: An oil-in-water emulsion cosmetic comprising: (a) a hygroscopic aqueous compound; (b) a polyglycerol fatty acid ester; (c) an oil; and (d) water. Aspect 2: The cosmetic according to Aspect 1, wherein the hygroscopic aqueous compound (a) is a cyclic carboxamide derivative represented by the following formula 1 or a salt thereof: In formula 1, R １ represents a hydrocarbon group having 1 to 6 carbon atoms which may be substituted with a hydroxyl group, or a hydrogen atom, and X represents -CH ２ - or -N(R ２ )—, where R ２ is a hydrocarbon group having 1 to 6 carbon atoms which may be substituted with a hydroxyl group, or a hydrogen atom, and n is an integer of 1 to 3. Aspect 3: The cosmetic according to Aspect 1 or 2, wherein the content of the (a) hygroscopic aqueous compound is 5.0% by mass or less. Aspect 4: The cosmetic according to any one of Aspects 1 to 3, wherein the fatty acid moiety of the (b) polyglycerin fatty acid ester has 12 to 14 carbon atoms. Aspect 5: The cosmetic according to any one of Aspects 1 to 4, wherein the polyglycerin moiety of the (b) polyglycerin fatty acid ester is formed from a polyglycerin having a degree of polymerization of 4 to 8. Aspect 6: The cosmetic according to any one of Aspects 1 to 5, wherein the content of the (b) polyglycerin fatty acid ester is 0.01% by mass or more and 1.5% by mass or less. Aspect 7 is a method for producing the oil-in-water emulsion cosmetic according to any one of Aspects 1 to 6, comprising: mixing the (a) hygroscopic aqueous compound, the (b) polyglycerol fatty acid ester, and the (d) aqueous phase component containing water to form a vesicle solution; and adding the (c) oil phase component containing an oil to the vesicle solution.

[0010] According to the present disclosure, it is possible to provide a novel oil-in-water emulsion cosmetic containing a hygroscopic aqueous compound, which has excellent usability and which overcomes problems such as stickiness that are associated with hygroscopic aqueous compounds.

[0011] FIG. 1 is a schematic diagram showing the arrangement of a hygroscopic aqueous compound and the like in an oil-in-water emulsion cosmetic according to one embodiment of the present disclosure.

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the present invention.

[0013] The oil-in-water emulsion cosmetic of the present disclosure contains (a) a hygroscopic aqueous compound, (b) a polyglycerol fatty acid ester, (c) an oil, and (d) water.

[0014] Although not limited by the theory, the principle of action by which the oil-in-water emulsion cosmetic of the present disclosure improves stickiness and other problems despite containing a hygroscopic aqueous compound is believed to be as follows.

[0015] Because hygroscopic aqueous compounds are aqueous, they are typically contained in the aqueous phase of oil-in-water emulsion cosmetics. While hygroscopic aqueous compounds are contained in the aqueous phase, they usually also contain hydrophobic moieties, which is thought to facilitate their integration within the aqueous phase. When the integrated and enlarged hygroscopic aqueous compounds are applied to the skin, they are thought to be more likely to absorb surrounding moisture, resulting in a sticky feeling.

[0016] The polyglycerol fatty acid ester used in the oil-in-water emulsion cosmetic of the present disclosure has a polyglycerol moiety and can function as a surfactant. Because this polyglycerol moiety has a hydroxyl group in the repeating unit, it is believed to have relatively strong hydrophilicity, i.e., a tendency to have a high affinity for aqueous components. As a result, it is believed that hygroscopic aqueous compounds in the aqueous phase are attracted to the polyglycerol moiety of the polyglycerol fatty acid ester present at the interface between the oil droplets and the aqueous phase, thereby inhibiting the hygroscopic aqueous compounds from combining with each other and dispersing them together with the oil droplets in the aqueous phase. In this state, the hygroscopic aqueous compounds are smaller than larger hygroscopic aqueous compounds that have combined, and have a lower ability to absorb surrounding moisture. Therefore, it is believed that problems such as a sticky feeling are less likely to occur when the cosmetic is applied to the skin.

[0017] In some embodiments, the polyglycerol fatty acid ester may be arranged in the form of a disk-shaped structure relative to the oil droplets, as shown in Figure 1, and function as a surfactant. Even in such cases, since the outermost layer contains a hydrophilic portion based on the polyglycerol portion, it is believed that the hygroscopic aqueous compound in the aqueous phase does not integrate with the oil droplets, but rather exists in a state coated on the surface of the polyglycerol fatty acid ester present around the oil droplets, as shown in Figure 1. As a result, it is believed that the hygroscopic aqueous compound does not integrate with the oil droplets, but disperses in the aqueous phase together with the oil droplets. As described above, a hygroscopic aqueous compound in such a state is less able to absorb surrounding moisture, and is therefore less likely to cause problems such as a sticky feeling when the cosmetic is applied to the skin.

[0018] Here, it is believed that the disk-shaped structures are formed as shown in Figure 1 when vesicles formed in an aqueous phase are disrupted, for example, by the influence of oil in the cosmetic, and a portion of the monolayers constituting the bilayers of the vesicles is adsorbed to the surface of the oil via the lipophilic portion (hydrophobic portion), and then the bilayers constituting the vesicles are stacked via the hydrophilic portion of the monolayers, or the monolayers constituting the bilayers of the vesicles are stacked via their hydrophilic portions or via their lipophilic portions. In this way, the disk-shaped structures are formed from monolayers having hydrophilic and lipophilic portions that constituted the bilayers of the vesicles. As a result, the disk-shaped structure laminate has the lipophilic portion (hydrophobic portion) located at the interface with the oil droplets and the hydrophilic portion located at the interface with the aqueous phase, and therefore, as a whole, can function similarly to a surfactant.

[0019] The monolayer made of polyglycerol fatty acid ester having hydrophilic and lipophilic parts has the ability to emulsify oil by itself.Therefore, when this monolayer material is used as a surfactant to emulsify water and oil, the monolayer material is not layered like a general surfactant, but is oriented near the interface between the oil droplet and the aqueous phase.However, in this state, the monolayer material generally does not remain near the interface with the aqueous phase in the oil droplet (emulsion particle), but is in an equilibrium state where it can move, for example, to the aqueous phase or the interface of other adjacent oil droplets.

[0020] On the other hand, it is believed that, like vesicles, disc-shaped structures in which monomolecular films having hydrophilic and lipophilic portions are laminated in layers reduce or inhibit movement in the aqueous phase or at the interface of adjacent oil droplets, etc., compared to general surfactants. As a result, when polyglycerol fatty acid esters are used in the form of disc-shaped structures, they can retain hygroscopic aqueous compounds for a longer period of time and further inhibit the growth of hygroscopic aqueous compounds, compared to when they are used as general surfactants, and therefore, it is believed that problems such as sticky feeling when cosmetics are applied to the skin are further improved.

[0021] Patent Document 2 describes that oil-in-water emulsion cosmetics containing disc-shaped structures can improve usability (stickiness resistance) as an additional effect. However, this stickiness resistance is an effect of improving stickiness associated with oil content, and not an effect of improving stickiness associated with hygroscopic aqueous compounds present in the aqueous phase. In other words, Patent Document 2 does not describe or suggest at all that oil-in-water emulsion cosmetics containing disc-shaped structures can also improve stickiness caused by sticky components present in the aqueous phase.

[0022] The definitions of terms used in this disclosure are as follows:

[0023] In the present disclosure, the term "disk-shaped structure" refers to a structure that does not form a closed endoplasmic reticulum structure like a vesicle, and whose cross-sectional shape is approximately plate-like (e.g., approximately square or approximately rectangular), as shown in Figure 1. Here, "approximately" does not allow for the cross-sectional shape of such a structure to be spherical like a vesicle, but it is acceptable for the structure to be deformed to some extent, for example, to be deformed so as to have a curvature that follows the shape of an oil droplet.

[0024] "Vesicles" in this disclosure also include liposomes and polymersomes.

[0025] In the present disclosure, "surfactant" also includes emulsifiers.

[0026] Oil-in-water emulsion cosmetic (sometimes simply referred to as "cosmetic") of the present disclosure contains a hygroscopic aqueous compound. The hygroscopic aqueous compounds can be used alone or in combination of two or more.

[0027] The amount of the hygroscopic aqueous compound is not particularly limited, and can be, for example, 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.5% by mass or more, or 1.0% by mass or more relative to the total amount of the cosmetic. From the viewpoint of usability (stickiness resistance), the upper limit of the amount is preferably 10% by mass or less, 7.0% by mass or less, or 5.0% by mass or less, more preferably less than 5.0% by mass, 4.5% by mass or less, or 4.0% by mass or less, and particularly preferably 3.5% by mass or less, or 3.0% by mass or less. The hygroscopic aqueous compound can be used appropriately within this range.

[0028] In the present disclosure, the term "hygroscopic aqueous compound" refers to a compound that can be dissolved or dispersed in water and that absorbs or adsorbs moisture, for example, in air under standard conditions (20°C, 1 atm, humidity 65%). Specific examples of such hygroscopic aqueous compounds include hydroxyl-containing polyhydric alcohols, pyrrolidone carboxylates, lactate salts, dipotassium glycyrrhizinate, and cyclic carboxamide derivatives or salts thereof represented by the following formula 1: In formula 1, R １ represents a hydrocarbon group having 1 or more, or 2 or more, and 6 or less, 5 or less, or 4 or less carbon atoms, which may be substituted with a hydroxyl group, or a hydrogen atom; X represents -CH ２ - or -N(R ２ )—, where R ２ is a hydrocarbon group having 1 or more, or 2 or more, and 6 or less, 5 or less, or 4 or less carbon atoms, which may be substituted with a hydroxyl group, or a hydrogen atom, and n is an integer of 1 to 3.

[0029] In particular, the configuration of the oil-in-water emulsion cosmetic of the present disclosure acts favorably on the cyclic carboxamide derivative represented by the above formula 1 or a salt thereof, thereby improving problems such as stickiness and improving usability.

[0030] R in the above formula 1 １ The hydrocarbon group in is not particularly limited, and examples thereof include alkyl groups, cycloalkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, haloalkyl groups, alkoxyalkyl groups, and alkoxycarbonylalkyl groups. Among these, from the viewpoint of the effect of improving problems such as stickiness, it is preferable that the hydrocarbon group is an alkyl group.

[0031] In some embodiments, the cyclic carboxamide derivative represented by Formula 1 is preferably R １ is a hydroxyalkyl group having 1 to 3 carbon atoms, and X is —CH ２ - or -NH-, and n is preferably 1. More specifically, the following cyclic carboxamide derivatives are more preferred, and 1-(2-hydroxyethyl)-2-imidazolidinone is particularly preferred:

[0032] The cyclic carboxamide derivative represented by the above formula 1 may be in the form of a salt. The type of salt is not particularly limited as long as it is a pharmacologically acceptable salt, and may be an inorganic salt or an organic salt.

[0033] Inorganic salts include, for example, hydrochloride, sulfate, phosphate, hydrobromide, sodium salt, potassium salt, magnesium salt, calcium salt, magnesium salt, and ammonium salt.

[0034] Organic salts include, for example, acetate, lactate, maleate, fumarate, tartrate, methanesulfonate, p-toluenesulfonate, triethanolamine salts, and amino acid salts.

[0035] These inorganic salts or organic salts can also be used for the above-mentioned pyrrolidone carboxylates and lactates.

[0036] (b) Polyglycerin Fatty Acid Ester The oil-in-water emulsion cosmetic of the present disclosure contains a polyglycerin fatty acid ester. In such cosmetics, the polyglycerin fatty acid ester may be used as is, like a conventional surfactant, or may be obtained by preparing a vesicle solution using the polyglycerin fatty acid ester as described in the method for producing an oil-in-water emulsion cosmetic below. The surfactant obtained by preparing a vesicle solution using the polyglycerin fatty acid ester can form a disc-shaped structure as shown in FIG. 1 . In other words, the oil-in-water emulsion cosmetic of the present disclosure may use a disc-shaped structure obtained by using the polyglycerin fatty acid ester as the surfactant. From the perspective of improving problems such as stickiness associated with hygroscopic aqueous compounds and improving usability, it is preferable to use a surfactant obtained by preparing a vesicle solution using the polyglycerin fatty acid ester, i.e., a disc-shaped structure. The polyglycerin fatty acid esters may be used alone or in combination.

[0037] From the viewpoint of improving stickiness and other drawbacks associated with hygroscopic aqueous compounds and improving usability, the blending amount of polyglycerol fatty acid ester is preferably 0.01% by mass or more or 0.05% by mass or more, more preferably 0.1% by mass or more, 0.3% by mass or more, or 0.5% by mass or more, relative to the total amount of the cosmetic, and is preferably 5.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, or 1.5% by mass or less, and more preferably less than 1.5% by mass, 1.3% by mass or less, or 1.0% by mass or less. The hygroscopic aqueous compound can be used appropriately within such ranges.

[0038] Polyglycerol fatty acid esters can be prepared by esterifying fatty acids with polyglycerol as shown in the following reaction scheme:

[0039] In the polyglycerol fatty acid ester, the portion derived from a fatty acid can be referred to as a fatty acid portion, and the portion derived from a polyglycerol can be referred to as a polyglycerol portion. The fatty acid portion corresponds to the lipophilic portion, and the polyglycerol portion corresponds to the hydrophilic portion.

[0040] From the viewpoint of improving stickiness and other drawbacks associated with hygroscopic aqueous compounds and improving usability, the polyglycerol fatty acid ester preferably has a fatty acid moiety having 12 or more, 13 or more, or 14 or more carbon atoms, and more preferably has a fatty acid moiety having 17 or less, 16 or less, 15 or less, or 14 or less carbon atoms.

[0041] The fatty acids that can be used to prepare the polyglycerol fatty acid esters may be saturated or unsaturated fatty acids, and may be straight-chain or branched-chain fatty acids. Examples of such fatty acids include lauric acid, myristic acid, and palmitic acid. Of these, myristic acid and lauric acid are preferred.

[0042] From the viewpoint of improving stickiness and other drawbacks associated with hygroscopic aqueous compounds and improving usability, the polyglycerin moiety of the polyglycerin fatty acid ester is preferably a trimer or more, or a tetramer or more, and is preferably a nonamer or less, 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 value of n of the polyglycerin fatty acid ester in the above reaction formula is, for example, the same as the value 2 in the dimer.

[0043] Specific examples of polyglycerol fatty acid esters include polyglyceryl-6 myristate, polyglyceryl-4 laurate, polyglyceryl-5 laurate, polyglyceryl-6 laurate, and polyglyceryl-10 palmitate. Of these, polyglyceryl-6 myristate and polyglyceryl-6 laurate are preferred from the viewpoints of improving stickiness and other problems associated with hygroscopic aqueous compounds and improving usability.

[0044] (Disc-shaped structure) In some embodiments, the oil-in-water emulsion cosmetic of the present disclosure comprises a disc-shaped structure containing a polyglycerol fatty acid ester as a surfactant. The polyglycerol fatty acid esters described above can be used as the polyglycerol fatty acid esters that constitute such disc-shaped structures.

[0045] The disk-shaped structure is formed by stacking monolayers having hydrophilic and lipophilic portions one on top of the other, and can be disposed at the interface between the oil droplet and the aqueous phase.

[0046] From the viewpoint of surface activity (emulsification performance), the number of stacked monomolecular layers may be 3 or more, or 5 or more. There is no particular upper limit to the number of stacked layers, and it may be, for example, 15 or less, 13 or less, 11 or less, 9 or less, or 7 or less.

[0047] 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 Figure 1, can be 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, 90 nm or less, or 80 nm or less, or can be 30 nm or more, 40 nm or more, or 50 nm or more. Here, when the cross section of the disk-shaped structure is deformed so as to have a curvature that follows the shape of the oil droplet, the maximum length refers to the length of the curved surface as shown in Figure 1.

[0048] For example, the presence or absence of disk-shaped structures and the maximum length of one side of the cross-sectional shape of the disk-shaped structures can be confirmed or determined using a freeze replica method from photographs taken with a freeze replica transmission electron microscope (TEM, H-7650: manufactured by Hitachi, Ltd.) The maximum length of one side of the cross-sectional shape of the disk-shaped structures is the average value of three or more (e.g., 10) arbitrarily selected disk-shaped structures.

[0049] As shown in Figure 1, the disk-shaped structures are believed to be formed when vesicles in the aqueous phase collapse, and a portion of the monolayers constituting the bilayers that constitute the vesicles adsorbs onto the surface of the oil via the lipophilic portion (hydrophobic portion), after which the bilayers that constitute the vesicles are laminated onto the hydrophilic portion of the monolayer, or when the monolayers that constitute the bilayers of the vesicles are laminated via their hydrophilic portions or via their lipophilic portions. In other words, the monolayers of the disk-shaped structures are typically composed of at least one surfactant (e.g., polyglycerol fatty acid ester) that can form vesicles. The presence or absence of vesicles in cosmetics can be confirmed, for example, by the freeze replica method using a freeze replica transmission electron microscope (TEM, H-7650: manufactured by Hitachi, Ltd.) or by using a small-angle X-ray scattering measurement device (SAXSess, manufactured by Anton Paar) and a Zetasizer Nano (manufactured by Malvern Panalytical).

[0050] In some embodiments, the disk-shaped structures are preferably formed from at least one polyglycerol fatty acid ester having an OH / C ratio of 0.30 to 0.80. Such an 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 preferably 0.80 or less, 0.75 or less, 0.70 or less, 0.65 or less, or 0.60 or less. Polyglycerol fatty acid esters having such an OH / C ratio are more likely to form disk-shaped structures, and can further improve the emulsion stability of oil-in-water emulsion cosmetics and the effect of improving problems such as stickiness associated with hygroscopic aqueous compounds.

[0051] Here, in the present disclosure, the "OH / C ratio" refers to the ratio of the number of hydroxyl groups in the polyglycerol moiety to the number of carbon atoms in the fatty acid moiety, and is a parameter relating to the balance between hydrophilicity and lipophilicity. For example, in the case of polyglyceryl-6 myristate, the fatty acid moiety has 14 carbon atoms, and the polyglycerol moiety is a hexamer, with 7 hydroxyl groups (=6+1), so the OH / C ratio is 0.50 (=7 / 14).

[0052] Specific examples of polyglycerol fatty acid esters that can form the disc-shaped structures include polyglyceryl-6 myristate, polyglyceryl-4 laurate, polyglyceryl-5 laurate, polyglyceryl-6 laurate, and polyglyceryl-10 palmitate. Of these, polyglyceryl-6 myristate and polyglyceryl-6 laurate are preferred from the viewpoints of improving stickiness and other problems associated with hygroscopic aqueous compounds and improving usability.

[0053] <(c) Oil> The oil-in-water emulsion cosmetic of the present disclosure contains an oil. The oil can constitute oil droplets as an oil phase or a dispersed phase together with the polyglycerol fatty acid ester or the disk-shaped structures prepared using the polyglycerol fatty acid ester.

[0054] The disk-shaped structures can improve the emulsion stability of oil droplets in oil-in-water emulsion cosmetics. Therefore, in some embodiments, the average particle size of the oil droplets immediately after production can be, for example, 10 μm or less, 7 μm or less, 5 μm or less, or 3 μm or less. The lower limit of the average particle size is not particularly limited, but can be, for example, 500 nm or more, 700 nm or more, or 1 μm or more. Here, the average particle size of the oil droplets can be defined as the average value of the diameters of the projected area circles of 10 or more, preferably 100 or more, oil droplets observed with an optical microscope.

[0055] The oil content in the oil-in-water emulsion cosmetic of the present disclosure may be 0.5% by mass or more, 1.0% by mass or more, 2.0% by mass or more, 3.0% by mass or more, 5.0% by mass or more, 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, relative to the total amount of the cosmetic, and may be 50% by mass or less, 45% by mass or less, 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, 10% by mass or less, 7.0% by mass or less, or 5.0% by mass or less. The oil content can be used appropriately within these ranges.

[0056] The type of oil is not particularly limited, and for example, volatile oils and non-volatile oils can be used. The oils can be used alone or in combination of two or more. Here, "volatile" refers to a material that exhibits a volatile content of more than 5% when left at 105°C under atmospheric pressure for 3 hours. The volatile content, which serves as an indicator of 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. This boiling point can be 250°C or less, 240°C or less, or 230°C or less, or 80°C or more, 100°C or more, 120°C or more, 150°C or more, or 160°C or more. Furthermore, in the present disclosure, "non-volatile" refers to a material that exhibits a volatile content of 5% or less when left at 105°C for 3 hours.

[0057] The volatile oil is not particularly limited, and examples thereof include volatile silicone oils and volatile hydrocarbon oils. The volatile oils may be used alone or in combination.

[0058] Volatile silicone oils include, for example, volatile acyclic silicone oils and volatile cyclic silicone oils.

[0059] As the volatile acyclic silicone oil, for example, a volatile linear silicone oil and a volatile branched silicone oil can be used.

[0060] Examples of volatile linear silicone oils include low-molecular-weight linear dimethylpolysiloxanes such as 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. Here, these viscosities refer to kinematic viscosities in an atmosphere at 25°C.

[0061] Examples of volatile branched silicone oils include low molecular weight branched siloxanes such as methyl trimethicone, tris(trimethylsilyl)methylsilane, and tetrakis(trimethylsilyl)silane.

[0062] Volatile cyclic silicone oils include, for example, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane.

[0063] Volatile hydrocarbon oils can include, for example, heptane, isododecane, isohexadecane, and isodecane.

[0064] In addition to the volatile oils described above, examples of oils include oils commonly used in cosmetics, such as liquid oils, solid oils, waxes, hydrocarbon oils other than those described above, silicone oils other than those described above, and polar oils. Some ultraviolet absorbers act as oils, particularly polar oils. Such ultraviolet absorbers can also be considered as oils.

[0065] Examples of liquid oils and fats 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, camellia oil, castor oil, linseed oil, safflower oil, cottonseed oil, perilla oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, Chinese tung oil, Japanese tung oil, jojoba oil, germ oil, and triglycerin.

[0066] Examples of solid fats and oils include cocoa butter, coconut oil, horse fat, hardened coconut oil, palm oil, beef tallow, mutton tallow, hardened beef tallow, palm kernel oil, lard, beef bone fat, Japan wax kernel oil, hardened oil, beef foot fat, Japan wax, and hardened castor oil.

[0067] Examples of waxes include beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, privet wax, spermaceti, montan wax, rice bran wax, lanolin, kapok wax, acetated lanolin, liquid lanolin, sugarcane wax, lanolin fatty acid isopropyl, 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.

[0068] Examples of hydrocarbon oils include liquid paraffin, ozokerite, squalane, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax, and olefin oligomers.

[0069] Examples of silicone oils include chain silicones such as dimethylpolysiloxane (dimethicone), methylphenylpolysiloxane (diphenylsiloxyphenyltrimethicone), and methylhydrogenpolysiloxane, all of which have a viscosity of 6 cs or more.

[0070] As the polar oil, for example, a polar oil having 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), and isotridecyl isononanoate (IOB value = 0.11). OB 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), adipic acid 2-Hexyldecyl (IOB value=0.16), diisopropyl sebacate (IOB value=0.40), ethylhexyl methoxycinnamate (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 caprylic / capric triglyceride (IOB value=0.33).

[0071] Examples of ultraviolet absorbers that can be considered to be oils include ultraviolet absorbers with an IOB of 0.10 or more, specifically organic ultraviolet absorbers such as ethylhexyl methoxycinnamate, octocrylene, polysilicone-15, t-butyl methoxydibenzoylmethane, ethylhexyl triazone, bisethylhexyloxyphenol methoxyphenyl triazine, diethylaminohydroxybenzoylhexyl benzoate, oxybenzone-3, methylenebisbenzotriazolyltetramethylbutylphenol, homosalate, and ethylhexyl salicylate. These ultraviolet absorbers can be used alone or in combination of two or more.

[0072] The IOB value of the polar oil and the UV absorber can be, for example, 0.11 or more, 0.12 or more, or 0.13 or more, and can be 0.50 or less, 0.45 or less, or 0.40 or less. Here, the IOB value is an abbreviation for Inorganic / Organic Balance (inorganic / organic ratio), and is a value representing the ratio of the inorganic value to the organic value, and is an index showing the degree of polarity of the organic compound. Specifically, the IOB value is expressed as IOB value = inorganic value / organic value. The "inorganic value" and "organic value" are set according to the type of atom or functional group, such as 20 for one carbon atom in a molecule and 100 for one hydroxyl group. The IOB value of an organic compound can be calculated by integrating the "inorganic values" and "organic values" of all atoms and functional groups in the organic compound (see, for example, "Organic Conceptual Diagram - Fundamentals and Applications" by Yoshio Koda, pp. 11-17, Sankyo Publishing, 1984).

[0073] In some embodiments, among the oils described above, polar oils are preferred, and cetyl ethylhexanoate is more preferred, from the viewpoints of emulsion stability of the oil-in-water emulsion cosmetic and the effect of improving problems such as stickiness associated with hygroscopic aqueous compounds.

[0074] <(d) Water> The oil-in-water emulsion cosmetic of the present disclosure contains water as a dispersion medium (aqueous phase).

[0075] The amount of water to be blended is not particularly limited, and can be, for example, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more, relative to the total amount of the cosmetic, and can be 95% by mass or less, 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. Water can be used appropriately within these ranges.

[0076] There are no particular limitations on the water that can be used in the oil-in-water emulsion cosmetic of the present disclosure, and for example, water used in cosmetics and quasi-drugs can be used, such as ion-exchanged water, distilled water, ultrapure water, and tap water.

[0077] <Optional Components> The oil-in-water emulsion cosmetic of the present disclosure may contain various components as appropriate, provided that they do not adversely affect the effects of the present disclosure. Examples of the various components include additives that are typically incorporated into cosmetics, such as surfactants other than the polyglycerol fatty acid esters described above, moisturizers, thickeners, neutralizers, water-soluble polymers, oil-soluble polymers, film-forming agents, higher fatty acids, sequestering agents, lower alcohols, higher alcohols, various extracts, sugars, amino acids, organic amines, polymer emulsions, chelating agents, UV absorbers other than the UV absorbers described above, pH adjusters, skin nutrients, vitamins, water-soluble drugs other than the hygroscopic aqueous compounds described above, oil-soluble drugs, buffers, anti-fading agents, preservatives, dispersants, propellants, fillers, pigments, dyes, colorants, and fragrances. The optional components may be incorporated into the oil phase and / or the aqueous phase, and may be used alone or in combination of two or more.

[0078] The polyglycerol fatty acid ester or the disc-shaped structures containing said polyglycerol fatty acid ester in the oil-in-water emulsion cosmetic of the present disclosure functions as a surfactant. Therefore, other surfactants may be blended into the cosmetic, but from the viewpoint of improving problems such as stickiness associated with hygroscopic aqueous compounds and improving usability, the blended amount of such other surfactants is preferably 5.0 mass% or less, 3.0 mass% or less, 1.0 mass% or less, 0.5 mass% or less, 0.1 mass% or less, or 0.01 mass% or less relative to the total amount of the cosmetic, and it is more preferable that such other surfactants not be blended at all.

[0079] <<Method for Producing Oil-in-Water Emulsion Cosmetic>> The oil-in-water emulsion cosmetic of the present disclosure can be produced as follows, but is not limited to the following method: In producing the cosmetic, the various materials described above can be used.

[0080] The hygroscopic aqueous compound and water are mixed to prepare an aqueous phase part, and the polyglycerol fatty acid ester and oil are mixed to prepare an oil phase part. The oil phase part is then added to the aqueous phase part, and the mixture is stirred and mixed to obtain the oil-in-water emulsion cosmetic of the present disclosure.

[0081] Alternatively, a vesicle solution is formed by mixing an aqueous phase component containing a hygroscopic aqueous compound, a polyglycerol fatty acid ester, and water. An oil-phase component containing an oil is then added to the vesicle solution, followed by stirring and mixing, thereby obtaining the oil-in-water emulsion cosmetic of the present disclosure. This method allows the formation of disc-shaped structures containing a polyglycerol fatty acid ester that can function as a surfactant.

[0082] Formulation of Oil-in-Water Emulsion Cosmetic There are no particular limitations on the formulation of the oil-in-water emulsion cosmetic of the present disclosure, and examples thereof include liquid, emulsion, cream, gel, spray, and mousse. Here, in the present disclosure, "spray" can include mist-type sprays, aerosol-type sprays, etc.

[0083] <<Uses of Oil-in-Water Emulsion Cosmetic>> The oil-in-water emulsion cosmetic of the present disclosure can be used, for example, as a cosmetic to be applied by spreading it onto the skin, hair, or the like.

[0084] The product form of the cosmetics of the present disclosure is not particularly limited, but examples thereof include facial cosmetics such as lotion, serum, emulsion, and pack; makeup cosmetics such as foundation, lipstick, and eye shadow; sunscreen cosmetics (sunscreen agents); body cosmetics; hair cosmetics such as hair liquid, hair tonic, hair conditioner, shampoo, rinse, and hair growth agent; ointments, etc.

[0085] The oil-in-water emulsion cosmetic of the present disclosure will be described in more detail below using examples, but the cosmetic of the present disclosure is not limited to these. Unless otherwise specified, the blending amounts are expressed in mass %. Furthermore, the evaluation methods described in the examples are not limited to the cosmetic described in the examples, and can also be applied to cosmetic compositions containing the above-mentioned components.

[0086] Examples 1 to 11 and Comparative Example 1 The oil-in-water emulsion cosmetics obtained by the formulations shown in Table 1 and the production methods shown below were evaluated as follows, and the results are shown in Table 1. Evaluation Method (Evaluation of Usability) Ten expert panelists evaluated the usability of each cosmetic when applied to the skin according to the following evaluation criteria. Here, because the speed at which the cosmetic blends into the skin correlates with stickiness, it can also be said that a cosmetic that blends into the skin quickly is a cosmetic that is non-sticky and has excellent usability: A: 7 to 10 panelists answered that the cosmetic blended into the skin quickly. B: 4 to 6 panelists answered that the cosmetic blended into the skin quickly. C: 0 to 3 panelists answered that the cosmetic blended into the skin quickly.

[0087] <Method for producing cosmetic preparations> Oil-in-water emulsion cosmetic preparations were produced by the following method using the formulation shown in Table 1. Here, the numbers shown below correspond to the numbers on the left side indicating the names of ingredients in the formulation in Table 1.

[0088] Example 1 Materials Nos. 1 to 5 and No. 9 were mixed uniformly with a mixer to obtain an aqueous phase part containing vesicles.

[0089] The oil component No. 8 was added to the obtained aqueous phase part and mixed uniformly with a stirrer to obtain the oil-in-water emulsion cosmetic of Example 1. Note that, because an aqueous phase part containing vesicles was used here, the polyglycerol fatty acid ester is expected to form a disk-shaped structure.

[0090] (Example 2) Materials No. 1 to No. 4 and No. 9 were mixed uniformly with a mixer to obtain an aqueous phase part.

[0091] Materials No. 5 and No. 8 were added to the obtained aqueous phase part and mixed uniformly using a stirrer to obtain the oil-in-water emulsion cosmetic of Example 2. Note that, because an aqueous phase part containing vesicles was not used here, it is expected that the polyglycerol fatty acid ester did not form disc-shaped structures.

[0092] (Examples 3 to 11) Oil-in-water emulsion cosmetics of Examples 3 to 11 were obtained in the same manner as Example 1, except for changing the formulation as shown in Table 1. Note that, since all of these compositions use an aqueous phase part containing vesicles, the polyglycerol fatty acid ester is expected to form a disk-shaped structure.

[0093] Comparative Example 1 Materials Nos. 1 to 4, 7, and 9 were mixed uniformly with a mixer to obtain an aqueous phase part.

[0094] The oil component No. 8 was added to the obtained aqueous phase part and mixed uniformly with a stirrer to obtain the oil-in-water emulsion cosmetic of Comparative Example 1.

[0095]

[0096] <Results> As described in Patent Documents 1 and 3, it is known that cosmetics containing hygroscopic aqueous compounds such as cyclic carboxamide derivatives are prone to problems such as stickiness. However, as is clear from the results in Table 1, it was confirmed that the oil-in-water emulsion cosmetics prepared using polyglycerol fatty acid esters are cosmetics that are quick to absorb into the skin and have excellent usability, despite containing hygroscopic aqueous compounds.

[0097] The results of Examples 1 and 2 show that the cosmetic of Example 1, obtained using an aqueous phase part containing vesicles, is superior in usability to the cosmetic of Example 2, obtained using an aqueous phase part not containing vesicles. This difference is thought to be due to the formation of disc-shaped structures containing polyglycerol fatty acid esters in Example 1.

[0098] From the results of Examples 3 to 5, it was found that the content of the hygroscopic aqueous compound is preferably 5.0% by mass or less, and more preferably less than 5.0% by mass, from the viewpoint of usability.

[0099] The results of Examples 6 and 7 show that the content of the thickener does not significantly affect the usability.

[0100] The results of Examples 8 to 10 show that, from the viewpoint of usability, the content of polyglycerol fatty acid ester is preferably 1.5% by mass or less, and more preferably less than 1.5% by mass.

[0101] The results of Example 11 show that polyglycerol fatty acid esters other than polyglyceryl-6 laurate can also exert the effect of improving usability.

Claims

1. An oil-in-water emulsion cosmetic comprising: (a) a hygroscopic aqueous compound; (b) a polyglycerol fatty acid ester; (c) an oil; and (d) water.

2. The cosmetic preparation according to claim 1, wherein the (a) hygroscopic aqueous compound is a cyclic carboxamide derivative represented by the following formula 1 or a salt thereof: In formula 1, R １ represents a hydrocarbon group having 1 to 6 carbon atoms which may be substituted with a hydroxyl group, or a hydrogen atom; X represents -CH ２ -or-N(R ２ )-, where R ２ represents a hydrocarbon group having 1 to 6 carbon atoms which may be substituted with a hydroxyl group, or a hydrogen atom, and n is an integer of 1 to 3.

3. A cosmetic preparation according to claim 1 or 2, wherein the content of the hygroscopic aqueous compound (a) is 5.0 mass% or less.

4. The cosmetic preparation according to claim 1 or 2, wherein the number of carbon atoms in the fatty acid moiety of the polyglycerin fatty acid ester (b) is 12 or more and 14 or less.

5. The cosmetic preparation according to claim 4, wherein the polyglycerin portion of the polyglycerin fatty acid ester (b) is formed from a polyglycerin having a polymerization degree of 4 or more and an octamer or less.

6. The cosmetic preparation according to claim 1 or 2, wherein the content of the polyglycerol fatty acid ester (b) is from 0.01% by mass to 1.5% by mass.

7. A method for producing the oil-in-water emulsion cosmetic according to claim 1 or 2, comprising: mixing the (a) hygroscopic aqueous compound, the (b) polyglycerol fatty acid ester, and the (d) aqueous phase component containing water to form a vesicle solution; and adding the (c) oil phase component containing an oil to the vesicle solution.

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