O / w-type pickering emulsion

Abstract

Provided is an O / W-type pickering emulsion exhibiting high stability in a long-term storage stability test and a freeze-thaw test.　The O / W-type pickering emulsion of the present invention comprises solid particles, an oil phase component, and an aqueous phase component, the O / W-type pickering emulsion being characterized in that: the solid particles are present at an interface between the oil phase component and the aqueous phase component; and when the solid particles are formed into a pellet under the following conditions, the contact angle of the pellet with respect to a 10 mass% 1,3-butylene glycol aqueous solution is more than 90 degrees and less than 180 degrees. Pellet formation conditions: the solid particles are placed inside a molding O-ring having an inner diameter of 35 mm, an outer diameter of 42 mm, and a thickness of 4 mm, and a load of 100 kN (10 tons) is applied for 10 seconds by a compression molding machine to form the pellet.

Description

O / W type Pickering emulsion

[0001] The present invention relates to an O / W type Pickering emulsion.

[0002] Oil-in-water (O / W) and water-in-oil (W / O) emulsions are applied to cosmetics and the like. Most of the emulsifiers used for emulsions are surfactants. Cosmetics containing surfactants may cause stickiness or greasiness when applied to the skin, resulting in a poor feel of use. When applied to the skin, irritation to the skin may become a problem. Furthermore, the cosmetics may be washed off by water such as sweat, and the water resistance may be a problem. In recent years, oil-in-water emulsified cosmetics that do not contain surfactants and utilize Pickering emulsification have been developed as cosmetics that cause no irritation to the skin and have good water resistance.

[0003] For example, Patent Document 1 discloses an oil-in-water type emulsified composition having solid particles, an oil phase component, and a water phase component, wherein the contact angle of the water phase component with respect to the solid particles is 90.0 degrees or less, the contact angle of the oil phase component with respect to the solid particles is 8.0 degrees or more and 90.0 degrees or less, the average diameter of the oil phase in the emulsified composition is 100 μm or less, and the solid particles are present at the interface between the oil phase component and the water phase component.

[0004] Further, Non-Patent Document 1 discloses that an O / W type Pickering emulsion is formed by using hydrophilic fine particles (solid particles).

[0005] Further, Non-Patent Document 2 discloses that solid particles having a high affinity for water stabilize an O / W type Pickering emulsion.

[0006] Japanese Patent No. 7347620

[0007] Functional Emulsions Stabilized with Polymer Particles, Oleo Science / Edited by the Editorial Committee of Oleo Science 9 (11), 511-517, 2009 Pickering Emulsion, J. Jpn. Soc. Colour Mater., 89(6) 203-206 (2016)

[0008] The oil-in-water emulsion composition described in Patent Document 1 uses a hydrophilic Pickering emulsifier (i.e., solid particles). As such, this oil-in-water emulsion composition exhibits high stability in short-term heating tests or low-temperature storage stability tests, but has issues with emulsion stability, including separation of the oil phase, in long-term storage stability tests and freeze-thaw tests.

[0009] The present invention was made to solve the above problems, and the object of the present invention is to provide an O / W type Pickering emulsion that exhibits high stability in long-term storage stability tests and freeze-thaw tests.

[0010] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention. Specifically, the present invention is an O / W type Pickering emulsion comprising solid particles, an oil phase component, and an aqueous phase component, wherein the solid particles are present at the interface between the oil phase component and the aqueous phase component, the solid particles are formed into pellets under the following conditions, and the contact angle of a 10% by mass 1,3-butylene glycol aqueous solution with respect to the pellets is greater than 90 degrees and less than 180 degrees.

[0011] According to the present invention, it is possible to provide an O / W type Pickering emulsion with excellent long-term storage stability.

[0012] The present invention is described in detail below. The O / W type Pickering emulsion of the present invention contains solid particles, an oil phase component, and an aqueous phase component, wherein the solid particles are present at the interface between the oil phase component and the aqueous phase component, and the solid particles are formed into pellets under the following conditions, and the contact angle of a 10% by mass 1,3-butylene glycol aqueous solution with respect to the pellets is greater than 90 degrees and less than 180 degrees. Pellet formation conditions: Solid particles are placed inside a molding O-ring with an inner diameter of 35 mm, an outer diameter of 42 mm, and a thickness of 4 mm, and pellets are formed by applying a load of 100 kN (10 tons) for 10 seconds using a compression molding machine.

[0013] The amount of solid particles used to form the pellets varies depending on the size of the solid particles and their properties, such as whether they are dense or porous. Therefore, it is preferable to use a sufficient amount of solid particles to measure the contact angle. For example, the weight of the solid particles used to form the pellets is preferably 5 to 10 g.

[0014] The O / W type Pickering emulsion of the present invention is an oil-in-water emulsion, so when it forms a cosmetic film, it provides a refreshing feel.

[0015] In the O / W type Pickering emulsion of the present invention, the solid particles are formed into pellets under the above conditions, and the contact angle of the 10% by mass 1,3-butylene glycol aqueous solution with respect to the pellets is greater than 90 degrees and less than 180 degrees. Preferably, the contact angle is between 100 and 160 degrees. In other words, in the O / W type Pickering emulsion of the present invention, the solid particles are hydrophobic. Therefore, the long-term storage stability of the O / W type Pickering emulsion of the present invention is enhanced.

[0016] By chemically modifying the surface of solid particles with a hydrophobic surface treatment agent (such as a silylation agent or silane coupling agent), the contact angle of the 10% butylene glycol aqueous solution with respect to the pellets can be set to more than 90 degrees and less than 180 degrees. Furthermore, the contact angle of the 10% butylene glycol aqueous solution with respect to the pellets can be controlled by adjusting the amount of surface treatment agent used to modify the surface of the solid particles.

[0017] The contact angle of a 10% by mass 1,3-butylene glycol aqueous solution to a pellet can be measured, for example, using a contact angle meter (model name: fully automatic contact angle meter DMo-702, manufacturer: Kyowa Interface Chemical Co., Ltd.). When measuring the contact angle, 10 μL of the aqueous phase component constituting the O / W type Pickering emulsion was dropped onto the molded pellet, and then measurements were taken over time. In evaluating the contact angle, to avoid the influence of water absorption by the pellet, the contact angle value at 0 seconds after dropping was used. If it is difficult to measure the contact angle at 0 seconds after dropping, the contact angle at the time of dropping may be calculated by linear approximation using measured values ​​within the range in which the change in contact angle with respect to time after dropping is linear. Furthermore, if the 10% by mass 1,3-butylene glycol aqueous solution is repelled from the pellet and does not drop onto it, the contact angle is considered to be 180 degrees in this specification.

[0018] The following describes preferred embodiments of the O / W type Pickering emulsion of the present invention.

[0019] <Solid Particles> In the O / W type Pickering emulsion of the present invention, the mass percentage of solid particles is preferably 0.5 to 10.0% by mass, and more preferably 1.0 to 5.0% by mass. When the mass percentage of solid particles is within the above range, the oil phase component and the aqueous phase component can be suitably emulsified.

[0020] In the O / W type Pickering emulsion of the present invention, the volume-average particle diameter of the solid particles is not particularly limited, but is preferably 0.2 to 0.4 μm. When the volume-average particle diameter of the solid particles is within the above range, the emulsification stability is increased, and when a cosmetic film is formed using the O / W type Pickering emulsion of the present invention, the feeling of squeaking is reduced.

[0021] In the O / W type Pickering emulsion of the present invention, the specific surface area of ​​the solid particles is not particularly limited, but is between 5 and 20 m². ２It is preferable that the specific surface area is within the above range. When the specific surface area of ​​the solid particles is within the above range, when a cosmetic film is formed using the O / W type Pickering emulsion of the present invention, squeaking originating from the solid particles is less likely to occur. Note that the specific surface area of ​​the solid particles refers to the BET specific surface area obtained by the BET method. The BET method is a gas adsorption method in which gas particles such as nitrogen are adsorbed onto solid particles, and the specific surface area is measured from the amount adsorbed. The specific surface area is determined by calculating the amount of monomolecular adsorption VM using the BET formula from the relationship between pressure P and the amount of adsorption V. In this specification, the specific surface area refers to the value measured by the BET multipoint method described in JIS 8830:2013.

[0022] In the O / W type Pickering emulsion of the present invention, from the viewpoint of storage stability of the formulation, the degree of hydrophobicity (M value) of the solid particles is preferably 10 to 35. Furthermore, in the O / W type Pickering emulsion of the present invention, from the viewpoint of the feel of the formulation, the degree of hydrophobicity (M value) of the solid particles is preferably 5 to 20, and more preferably 10 to 20.

[0023] In this specification, the degree of hydrophobicity (M value) of solid particles refers to the value measured by the following method: 1. Place a methanol aqueous solution prepared to a desired concentration (weight %) into a test tube and add the solid particles to be used as a sample until about half of the surface of the methanol aqueous solution is covered. 2. After standing, visually check whether the powder settles. 3. Perform the same procedure with methanol aqueous solutions of various concentrations and find the concentration at which settling of the solid particles is observed. The minimum methanol aqueous solution concentration at which settling occurs is defined as the M value.

[0024] In the O / W type Pickering emulsion of the present invention, the solid particles preferably contain silica and / or a metal oxide. Examples of metal oxides include titanium oxide, iron oxide, zinc oxide, aluminum oxide, lead oxide, and tin oxide.

[0025] In the O / W type Pickering emulsion of the present invention, it is preferable that the solid particles have hydrophilic and hydrophobic functional groups on their surface. By adjusting the ratio of hydrophilic and hydrophobic functional groups of the solid particles, the contact angle of a 10% by mass 1,3-butylene glycol aqueous solution with respect to pellets formed from the solid particles can be set to more than 90 degrees and less than 180 degrees. Examples of hydrophilic functional groups include hydroxyl groups. Hydrophobic functional groups can be imparted to the surface of solid particles by chemical modification. Preferably, alkoxysilanes and organosilazanes are used for this chemical modification. Examples of alkoxysilanes include methyltrimethoxysilane, dimethyltrimethoxysilane, phenyltrimethoxysilane, dimethoxydiphenylsilane, n-propylmethylmethoxysilane, hexyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propylethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, etc. Examples of organosilazanes include tetramethyldisilazane, hexamethyldisilazane, pentamethyldisilazane, etc.

[0026] Hydrophilic and hydrophobic functional groups can be imparted to the surface of solid particles by chemical modification.

[0027] Next, we will explain the method for producing the above-mentioned solid particles. First, prepare solid particles that have not undergone surface treatment (hereinafter also simply referred to as "untreated solid particles").

[0028] Untreated solid particles can be produced by deflagration, which involves oxidizing silicon powder or metal powder by dispersing it in an oxygen stream and igniting it. Alternatively, they can be produced by melting, which involves melting and spheroidizing silicon powder or metal powder in a flame. Generally, particles obtained by deflagration are dense and perfectly spherical. Of these methods, deflagration is the most preferred because, due to the perfectly spherical shape, uniform chemical modification can be achieved on the surface.

[0029] By chemically modifying the surface of such untreated solid particles, the contact angle of a 10% by mass 1,3-butylene glycol aqueous solution with respect to pellets formed from the solid particles can be set to more than 90 degrees and less than 180 degrees. Solid particles having the above parameters can be produced by this method.

[0030] More specifically, a method for producing solid particles using silica particles is described below. First, silica particles that have not undergone surface treatment are prepared. The silica particles are preferably silica particles obtained by the deflagration method and the melting method (hereinafter also referred to as "deflagration-type silica particles" and "melting-type silica particles," respectively), and deflagration-type silica particles are preferred.

[0031] Next, by chemically modifying the surface of the silica particles with hydrophobic functional groups, the contact angle of a 10% by mass 1,3-butylene glycol aqueous solution with respect to pellets formed from solid particles can be set to more than 90 degrees and less than 180 degrees.

[0032] Silica particles chemically modified with hydrophobic functional groups in this manner can be obtained by surface treatment using known silane coupling agents (alkoxysilanes, organosilazanes, etc.) to silylate silanol groups present on the surface of deflagration-processed silica particles or molten silica particles. The surface treatment can be performed on the silica particles in a dry state (dry method) or in some liquid (wet method). In other words, the surface treatment agent can be added and reacted after vaporization, or it can be dissolved in some solvent (or added and reacted as is if the surface treatment agent is a liquid). Of these, the wet method is preferred. Common solvents and liquids that can be used in the wet method include methyl ethyl ketone, acetone, methanol, ethanol, propanol, butanol, tetrahydrofuran, hexane, toluene, xylene, and water.

[0033] In such silica particles, at least a portion of the silanol groups on the surface will be silylated. The substitution efficiency in this case (the proportion of silanol groups on the surface that are silylated) is preferably 50 to 90%, and more preferably 50 to 80%.

[0034] The amount of carbon on the surface of silica particles is preferably 50 to 90% by mass of the carbon saturation amount, and more preferably 50 to 80% by mass, based on the mass of the silica particles. The carbon saturation amount on the surface of silica particles can be calculated from the amount of carbon in solid particles reacted with an excess amount of surface treatment agent. The amount of carbon on the surface of silica particles can be measured with a carbon analyzer (for example, model name: EMIA-Pro, manufactured by Horiba, Ltd.).

[0035] For chemical modification of the surface of silica particles, it is preferable to use alkoxysilanes and organosilazanes. Examples of alkoxysilanes include methyltrimethoxysilane, dimethyltrimethoxysilane, phenyltrimethoxysilane, dimethoxydiphenylsilane, n-propylmethylmethoxysilane, hexyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propylethoxysilane, hexyltriethoxysilane, and octyltriethoxysilane. Examples of organosilazanes include tetramethyldisilazane, hexamethyldisilazane, and pentamethyldisilazane, with hexamethyldisilazane being the most preferred from the viewpoint of use in cosmetics. The bond obtained by the reaction of the silanol group with the organosilazane is resistant to hydrolysis and cleavage over time, resulting in solid particles with excellent stability over time.

[0036] Furthermore, the silica particles used before surface treatment can be those available on the market. For example, deflagration-processed silica particles or molten silica particles such as AdmaFine SO-C1 (deflagration-processed silica particles manufactured by Admatex Corporation) can be used.

[0037] <Oil Phase Components> In the O / W type Pickering emulsion of the present invention, the oil phase component content is preferably 1 to 70% by volume.

[0038] The oil phase components contained in the O / W type Pickering emulsion of the present invention are not particularly limited and include natural oils and fats, silicone oils, hydrocarbon oils, synthetic ester oils, and the like.

[0039] Examples of natural 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, peach oil, wheat germ oil, sasanqua oil, castor oil, linseed oil, safflower oil, cottonseed oil, elm oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, cinnamon oil, Japanese tuni oil, jojoba oil, and wheat germ oil.

[0040] Examples of silicone oils include cyclic polysiloxanes such as cyclopentasiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane; linear polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, and caprylyl methicone; modified polysiloxanes such as amino-modified polysiloxane, polyether-modified polysiloxane, polyether-modified dimethylpolysiloxane, alkyl-modified polysiloxane, and fluorine-modified polysiloxane, or crosslinked products thereof.

[0041] Examples of hydrocarbon oils include isododecane, isohexadecane, squalane, squalene, paraffin, light isoparaffin, liquid paraffin, hydrogenated poly(C6-12 olefin), and pristane.

[0042] Examples of the synthetic ester oil include triethylhexanoin, isopropyl myristate, octyldodecyl myristate, isopropyl palmitate, hexyl laurate, decyl oleate, hexyldecyl dimethyloctanoate, lanolin acetate, isocetyl stearate, hexyldecyl isostearate, cetyl ethylhexanoate, neopentyl glycol dicaprate, diisostearyl malate, glyceryl triethylhexanoate trimethylolpropane triisostearate, trimethylolpropane triisostearate, pentaerythrityl tetraethylhexanoate, triethylhexanoin, triisopalmitin, trimethylolpropane triisostearate, ethylhexyl palmitate, trimyristin, oleyl oleate, diethylhexyl sebacate, isocetyl myristate, hexyldecyl palmitate, diisopropyl sebacate, diethylhexyl succinate, ethylhexyl palmitate, glyceryl tri(caprylate / caprate).

[0043] The oil phase component may contain wax, solid fats and oils, waxes, higher fatty acids, higher alcohols, and oil-soluble ultraviolet absorbers as long as the effects of the present invention are not impaired.

[0044] Examples of the solid fats and oils include cacao butter, coconut oil, horse fat, hydrogenated coconut oil, palm oil, beef tallow, mutton fat, hydrogenated beef tallow, palm kernel oil, lard, beef bone fat, mokuroku kernel oil, hydrogenated oil, beef foot fat, beeswax, hydrogenated castor oil, etc.

[0045] Examples of the waxes include beeswax, candelilla wax, cotton wax, carnauba wax, barberry wax, ibota wax, whale wax, montan wax, nuca 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, polyethylene glycol lanolin fatty acid, POE hydrogenated lanolin alcohol ether, etc.

[0046] Examples of the higher fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, undecylenic acid, tall oil acid and the like.

[0047] Examples of the higher alcohols include cetyl alcohol, stearyl alcohol, behenyl alcohol, batyl alcohol, myristyl alcohol, cetostearyl alcohol and the like.

[0048] Examples of oil-soluble UV absorbers include cinnamic acid derivatives such as polysilicone-15, 2-ethylhexyl paramethoxycinnamate, 2-ethoxyethyl paramethoxycinnamate, isopropyl paramethoxycinnamate / diisopropyl cinnamic acid ester mixture, methylbis(trimethylsiloxy)silylisopentyl trimethoxycinnamate; benzoic acid derivatives such as amyl paradimethylamino acid benzoate, 2-ethylhexyl paradimethylamino acid benzoate, ethylene glycol salicylate, 2-ethylhexyl salicylate, and salicylate. Salicylic acid derivatives such as benzyl salicylate, homomenthyl salicylate, and octocrylene; para-aminobenzoic acid, para-aminobenzoic acid monoglycerol ester, N,N-dipropoxypara-aminobenzoate ethyl ester, N,N-diethoxypara-aminobenzoate ethyl ester, homomenthyl-N-acetylantranilate, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone Benzophenone derivatives such as droxybenzophenone, 2-hydroxy-4-methoxybenzophenone (oxybenzone-3), 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4-phenylbenzophenone, 2-ethylhexyl-4'-phenylbenzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, and 4-hydroxy-3-carboxybenzophenone; 3-(4'-methylbenzylidene)- d,l-camphor, 3-benzylidene-d,l-camphor; 2-phenyl-5-methylbenzoxazole; 2,2'-hydroxy-5-methylphenylbenzotriazole; 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole; 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; dibenzarazine; dianisioylmethane; 5-(3,3-dimethyl-2-norbornylidene)-3-pentan-2-one; 4-t-butylmethoxydibenzoylmethane, octyltriazone;Examples include urocanic acid and ethyl urocanic acid, 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 1-(3,4-dimethoxyphenyl)-4,4-dimethyl-1,3-pentanedione, 2-ethylhexyl dimethoxybenzylidene dioxoimidazolidinepropionate, phenylbenzimidazazole sulfonic acid, terephthalylidene dicamphor sulfonic acid, drometrizole trisiloxane, methyl anthranilate, bis-ethylhexyloxyphenol methoxyphenyl triazine, rutin and its derivatives, oryzanol and its derivatives, etc.

[0049] <Aqueous Phase Components> In the O / W type Pickering emulsion of the present invention, the content of aqueous phase components is preferably 30 to 99% by volume.

[0050] The aqueous phase component contained in the O / W type Pickering emulsion of the present invention is not particularly limited and may include, for example, water and water-soluble alcohol.

[0051] The water used is preferably purified water or ionized water.

[0052] Examples of water-soluble alcohols include monohydric alcohols such as ethanol, 3-methoxy-1-butanol, or 3-methoxy-3-methyl-1-butanol; dihydric alcohols such as propylene glycol, dipropylene glycol, 1,3-butylene glycol, isopentyl diol, or tetraethylene glycol; polyhydric alcohols such as glycerin, diglycerin, polyglycerin, or polyethylene glycol (PEG-8, etc.); and sugars and sugar derivatives such as trehalose and glucosyltrehalose.

[0053] The water-soluble alcohol preferably has a water solubility of 500 g / L or more at 20°C. Examples of such water-soluble alcohols include ethanol (infinitely soluble in water), propylene glycol (infinitely soluble in water), dipropylene glycol (infinitely soluble in water), 1,3-butylene glycol (infinitely soluble in water), isopentyl diol (infinitely soluble in water), glycerin (infinitely soluble in water), polyethylene glycol (PEG-8, etc.) (water solubility at 20°C: 1000 g / L), and the like. Among these, ethanol, propylene glycol, dipropylene glycol, 1,3-butylene glycol, and isopentyl diol are preferred.

[0054] In the O / W type Pickering emulsion of the present invention, the weight ratio of water-soluble alcohol to water is preferably 1:99 to 40:60, and more preferably 1:99 to 30:70.

[0055] The aqueous phase components may include, to the extent that they do not impair the effects of the present invention, pH adjusters, aqueous thickeners, water-soluble ultraviolet absorbers, preservatives, humectants, polymers, amino acids and amino acid derivatives, sugars and sugar derivatives, fragrances, colorants, metal ion chelating agents, antioxidants, and pharmaceuticals.

[0056] As pH adjusters, sodium hydroxide, potassium hydroxide, arginine, triethanolamine, citric acid, ascorbic acid, glycolic acid, or succinic acid can be used.

[0057] It is preferable that the pH of the O / W type Pickering emulsion is adjusted to 5-7 at 25°C using a pH adjusting agent. Having the pH within this range improves the emulsion stability.

[0058] The mass percentage of the pH adjusting agent contained in the aqueous phase component is preferably 1% by mass or less.

[0059] Examples of water-based thickeners include water-soluble natural polymers, semi-synthetic polymers, synthetic polymers, and clay minerals. For example, natural polymers include xanthan gum, guar gum, and cellulose nanofibers; semi-synthetic polymers include derivatives of polysaccharides such as methylcellulose, ethylcellulose, hydroxyethylcellulose, and carboxymethylcellulose; synthetic polymers include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, and sodium acrylate graft starch; and clay minerals include bentonite and smectite. Of these, hydroxyethylcellulose, cellulose nanofibers, polyacrylic acid, (acrylates / alkyl acrylate (C10-30)) crosspolymer, acrylate copolymer, and sodium acrylate graft starch are preferred. The mass percentage of the thickener is preferably about 0.01% to 5% by mass.

[0060] The O / W type Pickering emulsion of the present invention can be used in cosmetics and quasi-drugs. The following describes how the O / W type Pickering emulsion of the present invention can be used in cosmetics.

[0061] When the O / W type Pickering emulsion of the present invention is used as a cosmetic, known ingredients used in cosmetics may be added to the O / W type Pickering emulsion of the present invention as appropriate, depending on the use and purpose, as long as the effects of the present invention are not impaired.

[0062] Known ingredients used in cosmetics include, for example, oily components, surfactants, water-miscible organic solvents, thickeners, inorganic powders, acids, emollients, polymers, amino acid derivatives, sugar derivatives, fragrances, colorants, antioxidants, and physiologically active substances.

[0063] Examples of oily components include oils, waxes, hydrocarbons, higher fatty acids, higher alcohols, and esters.

[0064] Examples of oils and waxes include almond oil, olive oil, hydrogenated oil, camellia oil, castor oil, coconut oil, silicone oil, beeswax, lanolin, and carnauba wax.

[0065] Hydrocarbons include linear or branched hydrocarbon oils, specifically squalane, ceresin, paraffin, liquid paraffin, petrolatum, etc.

[0066] Higher fatty acids include fatty acids with 12 to 30 carbon atoms, specifically lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, undecylenic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), isostearic acid, and 12-hydroxystearic acid.

[0067] Higher alcohols include alcohols with 8 to 30 carbon atoms, specifically including lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, behenyl alcohol, hexadecyl alcohol, oleyl alcohol, isostearyl alcohol, hexyldodecanol, octyldodecanol, cetostearyl alcohol, 2-decyltetradecinol, cholesterol, phytosterol, polyoxyethylene cholesterol ether, monostearyl glycerin ether (batyl alcohol), monooleyl glyceryl ether (cerakyl alcohol), etc.

[0068] Esters include ester oils with 3 to 100 carbon atoms, specifically including butyl stearate, cetyl lactate, myristyl lactate, isopropyl palmitate, isopropyl myristate, octyldodecyl myristate, myristyl myristate, hexyl laurate, glyceryl monostearate, and glyceryl di-2-heptylundecanoate.

[0069] Surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

[0070] Nonionic surfactants include aliphatic alcohol (8-24 carbon atoms) alkylene oxide (2-8 carbon atoms) adducts (degree of polymerization = 1-100) [e.g., oleyl alcohol ethylene oxide 11 molar adduct], (poly)oxyalkylene (2-8 carbon atoms, degree of polymerization = 1-100) glycol higher fatty acid (8-24 carbon atoms) esters [e.g., polyethylene glycol monostearate (degree of polymerization = 20) and polyethylene glycol distearate (degree of polymerization = 30)], polyhydric (2-10 or more carbon atoms) alcohol fatty acid (8-24 carbon atoms) esters [e.g., propylene glycol monolaurate, glyceryl monostearate, ethylene glycol monostearate and sorbitan monolaurate], and polyhydric (2-10 or more carbon atoms) alcohol higher fatty acid (8-24 carbon atoms) esters (poly Examples include alkylene oxide adducts (alkylene group with 2 to 8 carbon atoms, degree of polymerization = 1 to 100) [sorbitan monolaurate ethylene oxide (degree of polymerization = 10) adduct and methyl glucose dioleate ethylene oxide (degree of polymerization = 50) adduct, etc.], fatty acid N-hydroxyalkylamides [1:1 type coconut oil fatty acid diethanolamide and 1:1 type lauric acid diethanolamide, etc.], alkyl (1 to 22 carbon atoms) (poly)oxyalkylene (2 to 8 carbon atoms, degree of polymerization = 1 to 100) phenyl ethers, alkyl (8 to 24 carbon atoms) (poly)oxyalkylene (2 to 8 carbon atoms, degree of polymerization = 1 to 100)-aminoalkyl (8 to 24 carbon atoms)-ethers, and alkyl (8 to 24 carbon atoms) dialkyl (1 to 6 carbon atoms) amine oxides [lauryldimethylamine oxide, etc.].

[0071] Anionic surfactants include alkyl ether carboxylic acids or salts thereof with 8 to 24 carbon atoms and alkyl(poly)oxyethylene ether carboxylic acids or salts thereof with 8 to 24 carbon atoms [e.g., sodium (poly)oxyethylene (degree of polymerization = 1 to 100) lauryl ether acetate and disodium (poly)oxyethylene (degree of polymerization = 1 to 100) lauryl sulfosuccinate], alkyl sulfate ester salts and alkyl(poly)oxyethylene sulfate ester salts with 8 to 24 carbon atoms [e.g., sodium lauryl sulfate, sodium lauryl(poly)oxyethylene (degree of polymerization = 1 to 100) sulfate and sodium lauryl(poly)oxyethylene (degree of polymerization = 1 to 100) sulfate-triethanolamine salt], coconut oil fatty acid monoethanolamide sulfate sulfonate sodium, C8- Examples include 24 alkylphenyl sulfonates [such as sodium dodecylbenzenesulfonate], alkyl phosphate salts having 8 to 24 carbon atoms and alkyl(poly)oxyethylene phosphate salts having 8 to 24 carbon atoms [such as sodium lauryl phosphate and sodium (poly)oxyethylene (degree of polymerization = 1 to 100) lauryl ether phosphate], fatty acid salts [such as sodium laurate and triethanolamine laurate], and acylated amino acid salts [such as sodium methyl taurate, sodium sarcosinate, triethanolamine sarcosinate, triethanolamine acyl-L-glutamate, sodium acyl-L-glutamate, and sodium lauroylmethyl-β-alanine].

[0072] Examples of cationic surfactants include quaternary ammonium salts [such as stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, distearyldimethylammonium chloride, and lanolin fatty acid aminopropylethyldimethylammonium ethyl sulfate] and amine salts [such as diethylaminoethylamide lactate stearate, dilaurylamine hydrochloride, and oleylamine lactate].

[0073] Examples of amphoteric surfactants include betaine-type amphoteric surfactants [such as coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine, lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, lauryl hydroxysulfobetaine, and lauroylamide ethyl hydroxyethyl carboxymethyl betaine hydroxypropyl sodium phosphate] and amino acid-type amphoteric surfactants [such as β-laurylaminopropionate sodium].

[0074] Examples of water-miscible organic solvents include ethanol, isopropyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, glycerin, diglycerin, polyglycerin, 3-methyl-1,3-butanediol, 1,3-butanediol, 1,2-pentanediol, and 1,2-hexanediol.

[0075] Examples of thickening agents include guar gum, starch, carboxymethylcellulose, acetylmethylcellulose, polyvinyl alcohol, and sodium polyacrylate.

[0076] Examples of inorganic powders include zinc oxide, titanium oxide, barium sulfate, calcium sulfate, calcium carbonate, talc, mica, kaolin, mica, silica, aluminum silicate, hydroxyapatite, vermiculite, hydylite, bentonite, montmorillonite, hectorite, zeolite, ceramic powder, alumina, silica, and silylated silica.

[0077] Examples of acids include citric acid, tartaric acid, lactic acid, and phosphoric acid. Examples of alkalis include hydroxides of alkali metals (such as sodium and potassium) or alkaline earth metals (such as calcium), ammonia water, triethanolamine, diethanolamine, and monoethanolamine.

[0078] Examples of sugars include mannitol, sorbitol, xylitol, maltitol, erythritol, pentaerythritol, glucose, sucrose, fructose, lactose, maltose, xylose, and trehalose.

[0079] When using the O / W type Pickering emulsion of the present invention as a cosmetic, in addition to the above, ingredients commonly used in cosmetics [such as pigments, fragrances, hormones, vitamins, photosensitizers, plant and animal extracts, UV absorbers, antioxidants, preservatives / bactericides, antiperspirants / deodorants, etc., as described in "Latest Cosmetic Science" (published by Yakuji Nippo Co., Ltd.)] may be added.

[0080] The O / W type Pickering emulsion of the present invention is suitably used, for example, in skincare, haircare, and makeup applications. Examples of dosage forms when using the O / W type Pickering emulsion of the present invention include sprays, lotions, sheets, and powders. Specific applications include, for example, facial cleansers, washes, makeup removers, lotions, emulsions, gels, serums, packs, face masks, shaving lotions, sunscreens, after-sun lotions, sunscreen preparations, deodorant lotions, body lotions, hand care lotions, foot care lotions, lip balms, lip glosses, lip liners, hair waxes, hair mousses, hair gels, hair oils, hair sprays, hair mists, hair lotions, leave-in treatments, leave-in conditioners, powder foundations, liquid foundations, concealers, blushes, eyeliners, eyebrow products, eyeshadows, and lipsticks.

[0081] Next, an example of a method for producing the O / W type Pickering emulsion of the present invention (hereinafter also referred to as "first embodiment of the production method") will be described. The O / W type Pickering emulsion of the present invention can be produced by a dispersion step of dispersing solid particles in an aqueous phase component to obtain an aqueous dispersion, and an emulsification step of adding an oil phase component to the aqueous dispersion while stirring the dispersion.

[0082] <Dispersion Process> In this process, solid particles are added to the aqueous phase component and stirred using a known disperser such as a homomixer to disperse the solid particles in the aqueous phase component and obtain an aqueous dispersion.

[0083] Before stirring, pH adjusters and other components may be added to the aqueous phase. This preferably results in the pH of the aqueous dispersion being prepared being 7 to 14 at 25°C. By setting the pH of the aqueous dispersion to 7 to 14 at 25°C, the emulsification stability of the O / W type Pickering emulsion produced in subsequent processes can be improved.

[0084] To adjust the pH of the aqueous dispersion to 7-14 at 25°C, a pH adjusting agent may be used. Suitable pH adjusting agents include sodium hydroxide, potassium hydroxide, arginine, triethanolamine, citric acid, ascorbic acid, glycolic acid, or succinic acid.

[0085] The mass percentage of solid particles contained in the aqueous dispersion is preferably 1 to 30% by mass, based on the total mass of the aqueous dispersion.

[0086] The aqueous dispersion preferably contains an alcohol with a water solubility of 500 g / L or more at 20°C. Alternatively, the aqueous dispersion may consist solely of alcohol. Furthermore, it is more preferable that the pH of the aqueous dispersion at 25°C be between 7 and 14.

[0087] In addition, in this process, water-soluble components that can be added to cosmetics, such as water-soluble ultraviolet absorbers, preservatives, humectants, polymers, amino acids and amino acid derivatives, sugars and sugar derivatives, fragrances, colorants, metal ion chelating agents, antioxidants, and pharmaceuticals, may be added to the aqueous phase component.

[0088] <Emulsification Process> In this process, the oil phase component is added to the aqueous dispersion obtained in the dispersion process while stirring it. The emulsification process can be carried out by gradually adding the oil phase component to the aqueous dispersion at room temperature (preferably 15 to 25°C) while stirring it with a homomixer.

[0089] By performing this process, the O / W type Pickering emulsion of the present invention can be manufactured.

[0090] It is preferable to include an aqueous solvent addition step after the emulsification step, in which an aqueous solvent is added while maintaining stirring. By going through the aqueous solvent addition step, the dispersibility of the solid particles in water is reduced and the solid particles can be oriented at the oil phase interface.

[0091] Furthermore, after the step of adding an aqueous solvent, a step of adding an aqueous thickener and a step of adding a pH adjuster may be performed. Alternatively, the O / W type Pickering emulsion may be adjusted to a pH of 5.0 to 7.0, degassed, and left to stand overnight at 25 degrees Celsius in a standing step.

[0092] In addition, during this process, other ingredients that can be added to cosmetics, such as waxes, solid fats and oils, waxes, higher fatty acids, oil-soluble ultraviolet absorbers, powders, emollients, polymers, amino acid derivatives, sugar derivatives, fragrances, colorants, antioxidants, and physiologically active substances, may be added to the oil phase component.

[0093] Next, another example of a method for producing the O / W type Pickering emulsion of the present invention (hereinafter also referred to as "second embodiment of the production method") will be described. The O / W type Pickering emulsion of the present invention can be obtained by a dispersion step of dispersing solid particles in an oily component to obtain an oily dispersion, and an emulsification step of adding an aqueous phase component to the oily dispersion while stirring the oily dispersion.

[0094] Thus, even if the solid particles are dispersed in the oil phase component first, the O / W type Pickering emulsion of the present invention can be manufactured.

[0095] Furthermore, it is preferable that the materials used in the second aspect of the above manufacturing method are the same as the materials used in the first aspect of the above manufacturing method.

[0096] This specification contains the following information:

[0097] The present invention (1) is an O / W type Pickering emulsion comprising solid particles, an oil phase component, and an aqueous phase component, wherein the solid particles are present at the interface between the oil phase component and the aqueous phase component, the solid particles are formed into pellets under the following conditions, and the contact angle of a 10% by mass 1,3-butylene glycol aqueous solution with respect to the pellets is greater than 90 degrees and less than 180 degrees. Pellet formation conditions: Solid particles are placed inside a molding O-ring with an inner diameter of 35 mm, an outer diameter of 42 mm, and a thickness of 4 mm, and pellets are formed by applying a load of 100 kN (10 tons) for 10 seconds using a compression molding machine.

[0098] The present invention (2) is an O / W type Pickering emulsion according to the present invention (1), wherein the solid particles include silica and / or a metal oxide.

[0099] The present invention (3) is an O / W type Pickering emulsion according to the present invention (1) or (2), wherein the aqueous phase component comprises a water-soluble alcohol and water, and the weight ratio of the water-soluble alcohol to the water is water-soluble alcohol:water = 1:99 to 40:60.

[0100] The present invention (4) is an O / W type Pickering emulsion according to the present invention (3), wherein the water-soluble alcohol has a water solubility of 500 g / L or more at 20°C.

[0101] The present invention (5) is an O / W type Pickering emulsion according to any one of the present inventions (1) to (4), wherein the solid particles contain silica, at least a portion of the silanol groups on the surface of the solid particles are silylated, and the amount of carbon on the surface of the solid particles is 50 to 90% by mass of the saturation amount of carbon, based on the mass of the solid particles.

[0102] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0103] <Volume-average particle size> In the examples and comparative examples described later, silica particles were used as surface-untreated solid particles. The volume-average particle size of these silica particles was measured using a laser diffraction particle size distribution analyzer (Horiba, Ltd.). A solvent such as water or isopropyl alcohol was filled into the measurement cell of the laser diffraction particle size distribution analyzer, and silica powder was added little by little while applying ultrasound until the concentration was appropriate for measurement. The particle size distribution was measured once the appropriate concentration was achieved. The volume-average particle size of the silica particles used was 0.24 μm.

[0104] <BET specific surface area (m ２ The BET specific surface area of ​​silica particles was measured using a gas adsorption specific surface area measuring device (Shimadzu Corporation) according to the BET method described in JIS 8830:2013. Silica particles were weighed into the measuring cell of the surface area measuring device, heated to 200°C, cooled and heated with liquid nitrogen, and the specific surface area was calculated from the amount of gas released due to nitrogen detachment. The specific surface area of ​​the silica particles used was 16.4 m². ２ It was / g.

[0105] <Production of Solid Particles> (Production Example 1) Solid particles (E-1) according to Production Example 1 were prepared by surface-treating 100 parts by mass of deflagration-processed silica particles (product name: AdmaFine SO-C1, manufacturer: Admatex) with 0.66 parts by mass of a silylation agent (product name: SZ-31, manufacturer: Shin-Etsu Chemical Co., Ltd.) and substituting the hydroxyl groups on the surface of the silica particles with trimethylsilyl groups. The surface treatment with the silylation agent was carried out by the following method: 50 g of silica powder was added to 200 g of tetrahydrofuran, which is a solvent, and 6.6 mL of a 5% silylation agent / tetrohydroxyfuran solution was added to the solution while stirring with a stirring bar, and stirring was continued at room temperature for 5 hours to prepare a slurry. This slurry was filtered by suction filtration, and the resulting filtration cake was washed with methanol and then heat-treated at 130°C, and then pulverized in a mortar. In other words, the surface treatment of the silica particles was carried out by a wet method.

[0106] (Manufacturing Examples 2-5) and (Comparative Manufacturing Examples 1-2) Solid particles (E-2 to E-5) related to Manufacturing Examples 2-5, and solid particles (CE-1 and CE-2) related to Comparative Manufacturing Examples 1 and 2 were obtained in the same manner as Manufacturing Example 1, except that the materials and amounts used were changed as described in Table 1. The unit of the numerical values ​​of the components in Table 1 is "parts by mass". In Comparative Manufacturing Example 2 (CE-2), all hydroxyl groups on the surface of the solid particles were replaced with silyl groups by adding an excess amount of silylating agent.

[0107]

[0108] <Measurement of Contact Angle> 5 g of solid particles from each manufacturing example and each comparative manufacturing example were placed inside a molding O-ring with an inner diameter of 35 mm, an outer diameter of 42 mm, and a thickness of 4 mm. A 100 kN (10 tons) load was applied for 10 seconds using a compression molding machine (model name: Briquette Machine MP-35, manufacturer: Shimadzu Corporation) to form pellets. Subsequently, 10 μL of a 0-30 mass% 1,3-butylene glycol aqueous solution was brought into contact with the surface of each pellet, and the contact angle was measured using a contact angle meter (model name: Fully Automatic Contact Angle Meter DMo-702, manufacturer: Kyowa Interface Chemical Co., Ltd.). The results are shown in Table 1.

[0109] <Measurement of the Mass Ratio of Carbon on the Surface of Solid Particles> For each production example and each comparative production example, the amount of carbon on the surface of the solid particles was measured using a carbon analyzer (model name: EMIA-Pro, manufacturer: Horiba, Ltd.). Subsequently, the amount of carbon on the surface of the solid particles of comparative production example 2 (CE-2) was set as the saturation amount, and the mass ratio of carbon to the saturation amount of carbon for production examples 1 to 5 and comparative production example 1 was calculated. The results are shown in Table 1.

[0110] <Measurement of Hydrophobicity (M-value)> The degree of hydrophobicity (M-value) was measured for the solid particles in each production example and each comparative production example using the following method. The results are shown in Table 1. 1. A methanol aqueous solution prepared to an arbitrary concentration (weight %) was placed in a test tube, and the solid particles in each production example and each comparative production example were added until about half of the surface of the methanol aqueous solution was covered. 2. After standing, it was visually confirmed whether the powder settled. 3. The same procedure was performed with methanol aqueous solutions of various concentrations, and the concentration at which settling of the solid particles was confirmed was investigated. The minimum methanol aqueous solution concentration at which settling occurred was defined as the M-value.

[0111] (Examples 1) to (Examples 5) and (Comparative Example 1) to (Comparative Example 2) 1. Dispersion process 50 g of 1,3-butylene glycol was added to a 300 mL tall beaker with 0.15 g of a 10% by mass potassium hydroxide aqueous solution as an aqueous solution of pH adjusting agent and homogenized. Then, 7.5 g of the solid particles from each production example and each comparative production example were stirred in a homomixer for 1 minute (rotation speed 8000 rpm) to produce an aqueous dispersion.

[0112] 2. Emulsification Process After the production of the aqueous dispersion described above, while maintaining stirring, 50 g of liquid paraffin (Sonneborn, trade name "Carnation") as an oily component was added, and 1 minute later, 50.5 g of 1% by mass hydroxyethylcellulose (Tokyo Chemical Industries, trade name "Hydroxyethyl Cellulose" (200-300 mPa·s, 2% by mass in Water at 20℃)) as an aqueous solution of the other water-soluble component, an aqueous thickener, was added. While maintaining stirring, 0.15 g of 10% by mass citric acid aqueous solution (Tokyo Chemical Industries, trade name) as a pH adjuster was added. While maintaining stirring, 91.7 g of 0.55% by mass xanthan gum (Nisshin Oillio Group, trade name "Nomucoat Z") as an aqueous solution of the water-soluble component, an aqueous thickener, was added, and stirring was maintained until homogenization occurred.

[0113] 3. After the defoaming and settling emulsification process, the O / W type Pickering emulsions according to Examples 1-5 and Comparative Examples 1-2 were prepared by letting them stand overnight at 25°C after defoaming. The pH of each O / W type Pickering emulsion was measured at 25°C using a pH meter (Horiba, Ltd., F-71). The results are shown in Table 2.

[0114] <Visual Test> 40 mL of the obtained O / W type emulsion was placed in a 50 mL screw-cap tube, and the presence or absence of the aqueous and oil phases was checked. The evaluation criteria were as follows. The results are shown in Table 1. ○: Only the O / W emulsion phase was observed, and no separation was observed. ×: In addition to the emulsion phase, an oil phase was observed.

[0115] <Storage Stability Test> 40 mL of the obtained O / W type emulsion was placed in a 50 mL screw tube, and the presence or absence of the aqueous and oil phases was checked after one month of storage under three conditions. The conditions and evaluation criteria are as follows. The results are shown in Table 2.

[0116] (Storage conditions) - Constant temperature of 25°C, constant temperature of 50°C, alternating between 5°C for 12 hours and 40°C for 12 hours (cycle test)

[0117] (Evaluation Criteria) ○: Only the O / W emulsion phase is present, no phase separation ×: Separation of the oil phase is observed

[0118] <Freeze-thaw test> 40 mL of the obtained O / W type emulsion was placed in a 50 mL screw tube and stored at -5°C or below for more than half a day to completely freeze the aqueous phase. This test, which involved thawing at 25°C, was repeated three times to check for separation of the oil phase. The results are shown in Table 2.

[0119] (Evaluation Criteria) ○: Only the O / W emulsion phase is present, no phase separation ×: Separation of the oil phase is observed

[0120] <Evaluation of User Experience> Using the oil-in-water emulsions described in Examples 1-5 and Comparative Example 1, a panel of 10 experts evaluated the roughness and squeaky feeling of the product on their skin. Each panelist washed the inside of their forearm with water, dried it with a towel, and allowed it to dry for 15 minutes. Then, 1 g of the obtained oil-in-water emulsion was applied to the inside of their forearm. The sensory evaluation results for roughness and squeaky feeling were expressed as scores, and the average score was used for evaluation. The roughness and squeaky feeling when using the cosmetic product were evaluated on a scale of 1 to 5, and the average score of the 10 participants was calculated. The evaluation criteria are as follows. The results are shown in Table 2. 5 points: Excellent feel with no grittiness or squeaking caused by the powder. 4 points: Good feel with no grittiness or squeaking caused by the powder. 3 points: Average. 2 points: Slight grittiness or squeaking caused by the powder. 1 point: Strong grittiness or squeaking caused by the powder, poor feel.

[0121]

[0122] As shown in Table 2, the O / W type Pickering emulsions according to each example were found to have excellent long-term storage stability, stability in freeze-thaw tests, and usability.

[0123] The O / W type Pickering emulsion of the present invention exhibits excellent long-term storage stability, stability in freeze-thaw tests, and usability. Therefore, it can be suitably used in cosmetics and quasi-drugs that require long-term storage stability.

Claims

1. An O / W type Pickering emulsion comprising solid particles, an oil phase component, and an aqueous phase component, wherein the solid particles are present at the interface between the oil phase component and the aqueous phase component, the solid particles are formed into pellets under the following conditions, and the contact angle of a 10% by mass 1,3-butylene glycol aqueous solution with respect to the pellets is greater than 90 degrees and less than 180 degrees. Pellet formation conditions: Solid particles are placed inside a molding O-ring with an inner diameter of 35 mm, an outer diameter of 42 mm, and a thickness of 4 mm, and pellets are formed by applying a load of 100 kN (10 tons) for 10 seconds using a compression molding machine.

2. The O / W type Pickering emulsion according to claim 1, wherein the solid particles comprise silica and / or a metal oxide.

3. The O / W type Pickering emulsion according to claim 1 or 2, wherein the aqueous phase component comprises a water-soluble alcohol and water, and the weight ratio of the water-soluble alcohol to the water is water-soluble alcohol:water = 1:99 to 40:

60.

4. The O / W type Pickering emulsion according to claim 3, wherein the water-soluble alcohol has a water solubility of 500 g / L or more at 20°C.

5. The O / W type Pickering emulsion according to claim 1 or 2, wherein the solid particles contain silica, at least a portion of the silanol groups on the surface of the solid particles are silylated, and the amount of carbon on the surface of the solid particles is 50 to 90% by mass of the saturation amount of carbon, based on the mass of the solid particles.

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