Oil-in-water emulsion cosmetics

Abstract

To provide an oil-in-water emulsion cosmetic containing polyglycerol fatty acid ester that is stable even when preservatives are included.SOLUTION: The oil-in-water emulsion cosmetic of the present disclosure comprises (a) a polyglycerol fatty acid ester, (b) a nonionic surfactant having a sugar-derived structure, (c) a preservative, (d) an oil, and (e) water.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In the field of cosmetics, preservatives are sometimes added to prevent the cosmetics from spoiling.

[0003] Patent Document 1 discloses a cosmetic containing a specific polyether-modified silicone and a preservative.

[0004] Patent Document 2 discloses a preservative for cosmetics in which part or all of the ion-exchangeable ions in an aluminosilicate are substituted with antibacterial metal ions and ammonium ions and / or at least one type of amine ion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-006840 [Patent Document 2] Japanese Patent Application Publication No. 1-305013 Summary of the Invention [Problem to be solved by the invention]

[0006] When an oil-in-water emulsion cosmetic is prepared using a polyglycerol fatty acid ester, the emulsion stability of the cosmetic may be reduced if a preservative is simultaneously added.

[0007] Therefore, an object of the present disclosure is to provide an oil-in-water emulsion cosmetic containing a polyglycerol fatty acid ester, which is stable even when a preservative is contained therein. [Means for solving the problem]

[0008] <Aspect 1> (a) polyglycerol fatty acid ester, (b) a nonionic surfactant having a sugar-derived structure; (c) preservatives, (d) oils, and (e) water; Including, Oil-in-water emulsion cosmetics. <Aspect 2> A cosmetic preparation according to Aspect 1, wherein the (c) preservative comprises a compound having a benzene ring. <Aspect 3> Aspect 3. The cosmetic preparation according to aspect 2, wherein the compound having a benzene ring is at least one selected from the group consisting of phenoxyethanol and chlorphenesin. <Aspect 4> A cosmetic preparation according to any one of Aspects 1 to 3, wherein the content of the preservative (c) is 5.0% by mass or less. <Aspect 5> A cosmetic preparation according to any one of Aspects 1 to 4, wherein the number of carbon atoms in the fatty acid moiety of the (a) polyglycerol fatty acid ester is 8 or more and 17 or less. <Aspect 6> A cosmetic preparation according to aspect 5, wherein the polyglycerin moiety of the (a) polyglycerin fatty acid ester is formed from a polyglycerin having a polymerization degree of 4 or more and an polymerization degree of 8 or less. <Aspect 7> A cosmetic preparation according to any one of Aspects 1 to 6, wherein the (a) polyglycerol fatty acid ester comprises at least one selected from the group consisting of polyglyceryl-6 laurate and polyglyceryl-6 myristate. <Aspect 8> A cosmetic preparation according to any one of Aspects 1 to 7, wherein the content of the (a) polyglycerol fatty acid ester is from 0.01% by mass to 1.5% by mass. <Aspect 9> A cosmetic preparation according to any one of Aspects 1 to 8, wherein the (b) nonionic surfactant having a sugar-derived structure includes at least one selected from the group consisting of sucrose stearate and sorbitan tristearate. <Aspect 10> A cosmetic preparation according to any one of aspects 1 to 9, wherein the content of the (b) nonionic surfactant having a sugar-derived structure is 0.01% by mass or more. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide an oil-in-water emulsion cosmetic containing a polyglycerol fatty acid ester, which is stable even when a preservative is contained therein.

[0010] 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.

[0011] The oil-in-water emulsion cosmetic of the present disclosure contains (a) a polyglycerol fatty acid ester, (b) a nonionic surfactant having a sugar-derived structure, (c) a preservative, (d) an oil, and (e) water.

[0012] Without being limited by theory, the mechanism by which the oil-in-water emulsion cosmetic of the present disclosure containing a polyglycerol fatty acid ester improves emulsion stability despite containing a preservative is believed to be as follows.

[0013] The polyglycerol fatty acid ester used in the oil-in-water emulsion cosmetic of the present disclosure has a polyglycerol moiety and can therefore function as a surfactant. However, when a preservative is added to an oil-in-water emulsion cosmetic containing a polyglycerol fatty acid ester, the preservative is thought to interact with the polyglycerol fatty acid ester, reducing the surfactant function of the polyglycerol fatty acid ester, particularly its emulsifying function.

[0014] The present inventors have discovered that when an oil-in-water emulsion cosmetic is prepared using a polyglycerol fatty acid ester and a preservative, the emulsion stability of the cosmetic is improved by the combined use of a nonionic surfactant having a sugar-derived structure. The mechanism by which a nonionic surfactant having a sugar-derived structure improves the emulsion stability of a cosmetic is believed to be that such a surfactant interacts with the polyglycerol fatty acid ester, thereby assisting or reinforcing the surfactant function of the polyglycerol fatty acid ester, particularly its emulsifying function.

[0015] <Oil-in-water emulsion cosmetics> The oil-in-water emulsion cosmetic of the present disclosure has excellent emulsion stability. Here, emulsion stability can refer to a state in which the emulsion does not separate, and preferably to a state in which there is little change in the size of the emulsion particles (oil droplets), in an emulsion stability evaluation test described below in which the emulsion is left to stand for four weeks in an environment of 50°C. Note that such an emulsion stability test also corresponds to an accelerated test, and therefore an emulsion cosmetic that obtains good results in such a test can be said to have even better emulsion stability performance at room temperature (e.g., 5 to 35°C).

[0016] In some embodiments, the average particle size of the oil droplets in the oil-in-water emulsion cosmetic of the present disclosure can be, for example, 10 μm or less, less than 10 μm, 7 μm or less, 5 μm or less, or 3 μm or less immediately after preparation and / or after 4 weeks at 50°C. The lower limit of this 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.

[0017] In some embodiments, the oil-in-water emulsion cosmetic of the present disclosure can suppress the rate of oil droplet growth to 50% or less, 40% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less in an emulsion stability evaluation test in which the cosmetic is left in an environment of 50°C for 4 weeks, as described below. There is no particular restriction on the lower limit of the oil droplet growth rate, but it can be, for example, 0% or more or more. This growth rate can be calculated from the initial value of the average particle diameter of the oil droplets (the value immediately after preparation) and the value of the average particle diameter of the oil droplets after the emulsion stability test using the following formula 1: Increase rate (%) = {(average oil droplet size after emulsion stability test - initial average oil droplet size) × 100} / (initial average oil droplet size) ...Equation 1

[0018] (a) Polyglycerol fatty acid ester The oil-in-water emulsion cosmetic of the present disclosure (sometimes simply referred to as "cosmetic") contains a polyglycerol fatty acid ester. In such cosmetic, the polyglycerol fatty acid ester may be used as is, like a normal surfactant. The polyglycerol fatty acid ester can have the effect of reducing the particle size of oil droplets in the cosmetic. The polyglycerol fatty acid ester can be used alone or in combination of two or more types. The "surfactant" in the present disclosure may also include an emulsifier.

[0019] From the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction with the nonionic surfactant having a sugar-derived structure of component (b), which will be described later, the blending amount of the polyglycerol fatty acid ester is preferably 0.01% by mass or more or 0.05% by mass or more, more preferably 0.10% by mass or more, 0.15% by mass or more, or 0.20% by mass or more, 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, relative to the total amount of the cosmetic. The polyglycerol fatty acid ester can be used as appropriate within these ranges.

[0020] Polyglycerol fatty acid esters can be prepared by esterifying fatty acids with polyglycerol as shown in the following reaction scheme: [ka]

[0021] 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.

[0022] From the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic resulting from the interaction with the nonionic surfactant having a sugar-derived structure of component (b), which will be described later, the polyglycerol fatty acid ester preferably has 8 or more, 9 or more, 10 or more, 11 or more, or 12 or more carbon atoms in the fatty acid moiety, and preferably has 17 or less, 16 or less, 15 or less, or 14 or less carbon atoms.

[0023] The fatty acids that can be used when preparing the polyglycerol fatty acid ester may be saturated or unsaturated fatty acids, and may also be straight-chain or branched-chain fatty acids. Examples of such fatty acids include lauric acid, myristic acid, and palmitic acid. Among them, myristic acid and lauric acid are preferred from the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction with component (b) described below.

[0024] From the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction with component (b) described below, the polyglycerin moiety of the polyglycerin fatty acid ester is preferably a trimer or more, or a tetramer or more, and is also 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 for the dimer.

[0025] 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 viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction with component (b) described below.

[0026] (b) Nonionic Surfactant Having a Sugar-Derived Structure The oil-in-water emulsion cosmetic of the present disclosure contains a nonionic surfactant having a sugar-derived structure (sometimes simply referred to as a "sugar-derived nonionic surfactant"). Here, in the present disclosure, "sugar" refers to the initial oxidation product of a polyhydric alcohol, and can refer to a compound having a formyl group (-CHO) or a carbonyl group (>C=O). The sugar-derived nonionic surfactant can be used alone or in combination of two or more types.

[0027] From the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction with the polyglycerol fatty acid ester of component (a) described above, the blending amount of the sugar-derived nonionic surfactant is preferably 0.01% by mass or more or 0.05% by mass or more, more preferably 0.06% by mass or more, 0.07% by mass or more, 0.08% by mass or more, 0.09% by mass or more, or 0.10% by mass or more, 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 sugar-derived nonionic surfactant can be used appropriately within these ranges.

[0028] The sugar-derived structure in a sugar-derived nonionic surfactant is determined by the monosaccharide or disaccharide or higher sugar used. Such a structure may include, for example, a structure derived from a sugar alcohol obtained by reducing a monosaccharide or disaccharide or higher sugar. The sugar-derived structure can be obtained by using a monosaccharide or disaccharide or higher sugar alone or in combination of two or more types, either as is or in the form of a sugar alcohol.

[0029] Examples of structures derived from monosaccharides include residues derived from glucose, galactose, xylose, mannose, lyxose, arabinose, fructose, or mixtures thereof. Examples of sugars of disaccharides or higher include residues derived from maltose, trehalose, xylobiose, isomaltose, cellobiose, gentiobiose, lactose, sucrose, nigerose, turanose, raffinose, gentianose, menzitose, or mixtures thereof. Among these, glucose and sucrose are preferred from the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction with the polyglycerol fatty acid ester of component (a) described above.

[0030] In some embodiments, the sugar-derived nonionic surfactant includes a sugar fatty acid ester, such as sucrose fatty acid ester, maltitol fatty acid ester, and trehalose fatty acid ester.

[0031] The number of hydroxyl groups substituted by the fatty acid is not particularly limited, but from the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic resulting from the interaction with the polyglycerol fatty acid ester of component (a) described above, a monoester, diester, or triester is preferred, a monoester or diester is more preferred, and a monoester is particularly preferred.

[0032] Fatty acids that can constitute the fatty acid moiety of the sugar fatty acid ester are preferably saturated or unsaturated fatty acids having 12 to 22 carbon atoms, from the viewpoint of emulsion stability of the oil-in-water emulsion cosmetic due to interaction with the polyglycerol fatty acid ester of component (a) described above, and such fatty acids may be linear or branched. Examples of such fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachic acid, behenic acid, tetradecenoic acid, hexadecenoic acid, octadecenoic acid, octadecadienoic acid, eicosenoic acid, eicosatetraenoic acid, docosenoic acid, and octadecatrienoic acid, with stearic acid being particularly preferred. In the case of diesters or triesters, the fatty acids may be different.

[0033] From the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction with the polyglycerol fatty acid ester of component (a) described above, sucrose (cane sugar) fatty acid esters are preferred, with sucrose stearate (sometimes referred to as "sucrose monostearate"), sucrose distearate, or sucrose tristearate being more preferred, and sucrose stearate being particularly preferred.

[0034] In some embodiments, the sugar-derived nonionic surfactant includes a fatty acid ester of sorbitan.

[0035] The number of hydroxyl groups substituted by the fatty acid is not particularly limited, but from the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic resulting from the interaction with the polyglycerol fatty acid ester of component (a) described above, a monoester, diester, or triester is preferred, a diester or triester is more preferred, and a triester is particularly preferred.

[0036] Fatty acids that can constitute the fatty acid moiety of the sorbitan fatty acid ester are preferably saturated or unsaturated fatty acids having 12 to 22 carbon atoms, from the viewpoint of emulsion stability of the oil-in-water emulsion cosmetic due to interaction with the polyglycerol fatty acid ester of component (a) described above, and such fatty acids may be linear or branched. Examples of such fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachic acid, behenic acid, tetradecenoic acid, hexadecenoic acid, octadecenoic acid, octadecadienoic acid, eicosenoic acid, eicosatetraenoic acid, docosenoic acid, and octadecatrienoic acid, with stearic acid being particularly preferred. In the case of diesters or triesters, the fatty acids may be different.

[0037] From the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction with the polyglycerol fatty acid ester of component (a) described above, sorbitan stearate (sometimes referred to as "sorbitan monostearate"), sorbitan distearate, or sorbitan tristearate is preferred, sorbitan distearate or sorbitan tristearate is more preferred, and sorbitan tristearate is particularly preferred.

[0038] (d) Preservatives The oil-in-water emulsion cosmetic of the present disclosure contains a preservative. In the present disclosure, a "preservative" refers to an agent commonly used in the field of cosmetics, and is an agent for preventing deterioration of the cosmetic by suppressing changes in quality and odor, etc., that occur, for example, due to the growth of microorganisms accidentally mixed in when the cosmetic is used or handled. Preservatives can be used alone or in combination of two or more types.

[0039] The oil-in-water emulsion cosmetic of the present disclosure contains the sugar-derived nonionic surfactant component (b) described above, and exhibits excellent emulsion stability, allowing the incorporation of a preservative. The amount of preservative may be, for example, 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, or 0.5% by mass or more, relative to the total amount of the cosmetic. The upper limit of the amount may be, for example, 5.0% by mass or less, 4.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, or 1.0% by mass or less. The preservative may be used as appropriate within this range.

[0040] As the preservative, preservatives commonly used in the field of cosmetics can be used. In particular, compounds having a benzene ring tend to destabilize oil-in-water emulsion cosmetics containing the above-mentioned (a) polyglycerol fatty acid ester, but the oil-in-water emulsion cosmetics of the present disclosure contain the above-mentioned sugar-derived nonionic surfactant of component (b), and as a result, have excellent emulsion stability, so that such compounds having a benzene ring can be incorporated as preservatives.

[0041] Examples of compounds having a benzene ring include phenoxyethanol, chlorphenesin, benzoic acid, salicylic acid, alkyl parahydroxybenzoates, and hexachlorophene. Among these, phenoxyethanol and chlorphenesin are preservatives that can further destabilize the oil-in-water emulsion cosmetic containing the above-mentioned (a) polyglycerol fatty acid ester, but such preservatives can also be used in the oil-in-water emulsion cosmetic of the present disclosure. Compounds having a benzene ring can be used alone or in combination of two or more.

[0042] (d) Oil content The oil-in-water emulsion cosmetic of the present disclosure contains an oil component. Such oil component may constitute oil droplets as the oil phase or dispersed phase in the oil-in-water emulsion cosmetic.

[0043] The oil content in the oil-in-water emulsion cosmetic of the present disclosure can 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 can 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.

[0044] The type of oil is not particularly limited; for example, volatile oils and non-volatile oils can be used. The oils can be used alone or in combination. 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.

[0045] 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.

[0046] Volatile silicone oils include, for example, volatile acyclic silicone oils and volatile cyclic silicone oils.

[0047] As the volatile acyclic silicone oil, for example, a volatile linear silicone oil and a volatile branched silicone oil can be used.

[0048] 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.

[0049] Examples of volatile branched silicone oils include low molecular weight branched siloxanes such as methyl trimethicone, tris(trimethylsilyl)methylsilane, and tetrakis(trimethylsilyl)silane.

[0050] Volatile cyclic silicone oils include, for example, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane.

[0051] Volatile hydrocarbon oils can include, for example, heptane, isododecane, isohexadecane, and isodecane.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] Examples of waxes include beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, ivory 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.

[0056] Examples of hydrocarbon oils include liquid paraffin, ozokerite, squalane, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax, and olefin oligomers.

[0057] 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.

[0058] 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).

[0059] Examples of UV absorbers that can be considered to be oils include those with an IOB of 0.10 or more, specifically organic UV 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 UV absorbers can be used alone or in combination of two or more.

[0060] 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, which is a value representing the ratio of inorganic value to organic value and serves as an index of the degree of polarity of an 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 adding up the "inorganic value" and "organic value" 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).

[0061] In some embodiments, among the oils described above, polar oils are preferred, and pentaerythrityl tetraethylhexanoate is more preferred, from the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic that accompanies the interaction between the above-described components (a) and (b).

[0062] 〈(e)Water〉 The oil-in-water emulsion cosmetic of the present disclosure contains water as a dispersion medium (aqueous phase).

[0063] 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, and can be 95% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, or 50% by mass or less, relative to the total amount of the cosmetic. Water can be used appropriately within these ranges.

[0064] 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.

[0065] <Optional ingredients> The oil-in-water emulsion cosmetic of the present disclosure can be appropriately blended with various components as long as they do not adversely affect the effects of the present disclosure. These components include additives typically found in cosmetics, such as surfactants (e.g., anionic surfactants) other than the polyglycerol fatty acid esters and nonionic surfactants having sugar-derived structures described above, moisturizers, thickeners, neutralizers, water-soluble polymers, oil-soluble polymers, film-forming agents, higher fatty acids, sequestering agents, lower alcohols (e.g., ethanol), 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, oil-soluble drugs, buffers, anti-fading agents, dispersants, propellants, fillers, pigments, dyes, colorants, and fragrances. Optional components can be blended in the oil phase and / or the aqueous phase and can be used alone or in combination.

[0066] In the oil-in-water emulsion cosmetic of the present disclosure, the polyglycerol fatty acid ester can function as a surfactant that contributes to emulsification, and the nonionic surfactant having a sugar-derived structure can function as an adjuvant or reinforcer for the polyglycerol fatty acid ester. Therefore, while other surfactants may be blended into the cosmetic, from the viewpoint of the emulsion stability of the oil-in-water emulsion cosmetic due to the interaction between the polyglycerol fatty acid ester and the nonionic surfactant having a sugar-derived structure, the blending amount of other surfactants is preferably 5.0% by mass or less, 3.0% by mass or less, 1.0% by mass or less, 0.5% by mass or less, 0.1% by mass or less, 0.05% by mass or less, or 0.01% by mass or less, relative to the total amount of the cosmetic; and it is more preferable that such other surfactants not be blended.

[0067] <<Method for producing oil-in-water emulsion cosmetics>> The oil-in-water emulsion cosmetic of the present disclosure can be produced as follows, although the method is not limited to the following: In producing the cosmetic, the various materials described above can be used.

[0068] An aqueous phase part is prepared by mixing a preservative and water, and an oil phase part is prepared by mixing a polyglycerol fatty acid ester, a nonionic surfactant having a sugar-derived structure, and an oil component. The oil phase part is then added to the aqueous phase part, followed by stirring and mixing, to obtain the oil-in-water emulsion cosmetic of the present disclosure.

[0069] <<Formulation of oil-in-water emulsion cosmetics>> The formulation of the oil-in-water emulsion cosmetic of the present disclosure is not particularly limited, and examples thereof include liquid, emulsion, cream, gel, spray, and mousse. Here, in the present disclosure, the term "spray" can include mist-type sprays, aerosol-type sprays, etc.

[0070] <<Uses of oil-in-water emulsion cosmetics>> 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.

[0071] The product form of the cosmetics of the present disclosure is not particularly limited, but examples 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. [Example]

[0072] 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.

[0073] Reference Examples 1 to 2, Examples 1 to 5, and Comparative Examples 1 to 4 The oil-in-water emulsion cosmetic was prepared by mixing the ingredients in the formulation shown in Table 1 in a conventional manner, and the following evaluations were carried out. The results are shown in Table 1.

[0074] Evaluation Method (Initial particle size evaluation test for oil droplets) The size (diameter) of 10 oil droplets randomly extracted within one hour of preparing the emulsion cosmetic was observed under an optical microscope, and the average value was used to evaluate the size (diameter) of the oil droplets according to the following criteria: A: The average particle size of the oil droplets was 5 μm or less. B: The average particle size of the oil droplets was more than 5 μm and 10 μm or less. C: The average particle size of the oil droplets was more than 10 μm.

[0075] (Emulsion stability evaluation test) The size (diameter) of the oil droplets within 1 hour after the emulsion cosmetic was prepared and after 4 weeks of storage at 50°C were observed using an optical microscope, and the emulsion stability was evaluated according to the following criteria, where A and B are considered to be acceptable, and C is considered to be unacceptable: A: There was almost no change in the size of the oil droplets. B: The oil droplet size increased slightly. C: The oil droplet size was clearly increased or the cosmetic separated.

[0076] [Table 1]

[0077] <result> As is clear from the results of Reference Example 2, the inclusion of a preservative did not adversely affect emulsion stability unless a polyglycerol fatty acid ester was used. However, as is clear from the results of Reference Example 1, Comparative Example 1, and Comparative Example 4, it was confirmed that when a polyglycerol fatty acid ester was used and a preservative was added, emulsion stability was reduced.

[0078] On the other hand, the results of Examples 1 to 5 and Comparative Examples 2 and 3 confirmed that when a nonionic surfactant having a sugar-derived structure was added, even in an oil-in-water emulsion cosmetic containing a polyglycerol fatty acid ester and a preservative, excellent emulsion stability was achieved.

Claims

1. (a) polyglycerol fatty acid ester, (b) a nonionic surfactant having a sugar-derived structure; (c) preservatives; (d) oils, and (e) water; Including, Oil-in-water emulsion cosmetics.

2. The cosmetic preparation according to claim 1 , wherein the preservative (c) comprises a compound having a benzene ring.

3. The cosmetic according to claim 2, wherein the compound having a benzene ring is at least one selected from the group consisting of phenoxyethanol and chlorphenesin.

4. The cosmetic preparation according to claim 1 or 2, wherein the content of the preservative (c) is 5.0% by mass or less.

5. 3. The cosmetic according to claim 1, wherein the number of carbon atoms in the fatty acid moiety of the polyglycerol fatty acid ester (a) is 8 or more and 17 or less.

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

7. 3. The cosmetic according to claim 1, wherein the (a) polyglycerol fatty acid ester comprises at least one selected from the group consisting of polyglyceryl-6 laurate and polyglyceryl-6 myristate.

8. The cosmetic preparation according to claim 1 or 2, wherein the content of the polyglycerol fatty acid ester (a) is 0.01% by mass or more and 1.5% by mass or less.

9. The cosmetic preparation according to claim 1 or 2, wherein the (b) nonionic surfactant having a sugar-derived structure comprises at least one selected from the group consisting of sucrose stearate and sorbitan tristearate.

10. The cosmetic preparation according to claim 1 or 2, wherein the content of the nonionic surfactant (b) having a sugar-derived structure is 0.01% by mass or more.

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