JP2020050626A - Visible light-translucent pickering emulsion - Google Patents

Abstract

To provide a Pickering emulsion excellent in a cool feeling of appearance and water resistance.SOLUTION: A visible light-translucent Pickering emulsion contains an aqueous phase containing polyol and/or thickener, an oil phase, and powder.SELECTED DRAWING: None

Description

  The present invention relates to a pickering emulsion having a visible light transmittance.

  A dosage form emulsified by adsorbing amphiphilic solid particles at an interface is conventionally known as a Pickering emulsion, and its use has been proposed in cosmetics. For example, titanium dioxide, zinc oxide, and the like have been proposed as the solid particles, and the use of solid particles obtained by hydrophobizing the surfaces thereof for the preparation of Pickering emulsions has been proposed (Patent Document 1). Further, an oil-in-water emulsified emulsion using partially hydrophobized silica has also been proposed, and is considered to be excellent in high-temperature emulsification stability (Patent Document 2).

  Since the Pickering emulsion has an oil phase, an aqueous phase, and a powder, it generally has a cloudy appearance due to light scattering at an interface between these constituent components, has a poor refreshing feeling, and has After coating, whitening sometimes occurred.

  By the way, the water-in-oil type emulsified cosmetic is easy to impart water resistance since the external phase is an oil agent, and is a dosage form often used for sunscreens and the like. For example, Patent Document 3 discloses a water-in-oil emulsified cosmetic for sunscreen containing an ultraviolet absorbent, and describes that this cosmetic has excellent water resistance.

JP 2001-518111 A JP 2013-129626 A JP 2011-126832 A

  An object of the present invention is to provide a Pickering emulsion having excellent refreshing feeling and sweat resistance.

Further, as described above, the water resistance effect of the conventional water-in-oil type emulsified cosmetic is derived from the property that the oil agent constituting the external phase is incompatible with water.
However, when the present water-in-oil type emulsified cosmetic comes in contact with an aqueous solution containing ions such as seawater and sweat, the present inventors react with the hydrophilic groups of the oil agent constituting the external phase and react with the ions. It has been found that there is a problem that the oil solution is eluted by becoming a salt. In other words, although the conventional water-in-oil type emulsified cosmetics claim to have a water-resistant effect, they are inferior in sweat resistance and seawater resistance and contravene the effective power.

  In view of the above problems, a preferred embodiment of the present invention aims to provide a Pickering emulsion that is resistant to an aqueous solution containing ions such as seawater and sweat.

The present inventors have made tremendous research efforts, and have surprisingly discovered that Pickering emulsions having visible light transmittance to improve the apparent coolness are also excellent in sweat resistance. Completed the invention.
The present invention which solves the above-mentioned problems is a pickering emulsion having visible light transmittance, comprising an aqueous phase containing a polyol and / or a thickener, an oil phase, and a powder.
The Pickering emulsion of the present invention has a visible coolness due to having visible light transmittance, and also has excellent sweat resistance.

In a preferred embodiment of the present invention, the relative refractive index of the powder with respect to the oil phase is 0.7 to 1.3.
By using a powder having a relative refractive index with respect to the oil phase within the above range, the apparent refreshing feeling and sweat resistance of the pickering emulsion can be improved.

In a preferred embodiment of the present invention, the relative refractive index of the water phase to the oil phase is 0.8 to 1.2.
By setting the relative refractive index of the aqueous phase to the oil phase in the above range, the apparent coolness and sweat resistance of the pickering emulsion can be improved.

In a preferred embodiment of the present invention, the water phase contains at least 30% by mass of a polyol.
The Pickering emulsion of the present invention containing the polyol in the above range is more excellent in transparency and sweat resistance.

In a preferred embodiment of the present invention, the aqueous phase contains 0.1% by weight or more of a thickener.
The Pickering emulsion of the present invention containing the thickener in the above range is more excellent in transparency and sweat resistance.

In a preferred embodiment of the present invention, the viscosity at 25 ° C. and 1 atm is 4000 mPa · s or more.
The Pickering emulsion of the present invention having such a viscosity has excellent stability.

In a preferred embodiment of the present invention, the powder is a partially hydrophobized powder whose surface is partially coated with a hydrophobizing agent.
By using the partially hydrophobized powder, a Pickering emulsion having excellent sweat resistance and stability can be provided.

The pickering emulsion of the present invention is excellent in a refreshing feeling and sweat resistance in appearance. In a preferred embodiment, the Pickering emulsion of the present invention has excellent moisture retention.
Further, the Pickering emulsion of the present invention has excellent resistance to an aqueous solution containing ions.

5 is a bar graph showing the zeta potential of partially hydrophobized silica when dispersed in pure water and seawater. It is a bar graph showing the amount of ethylhexyl methoxycinnamate eluted from the coating films of the emulsions of Reference Example 1 and Comparative Example 4 into seawater. 4 is an electron micrograph showing a cross section of a coating film of the emulsion of Reference Example 1 and Comparative Example 4 before and after immersion in seawater. It is a bar graph showing the SPF value of the coating film of the emulsion of Reference Example 1 and Comparative Example 4 after immersion in seawater, based on the SPF value before immersion in seawater. 5 is a graph showing the light scattering rate of the ultraviolet region of the coating film of the emulsion of Reference Example 1 before and after contact with seawater. 9 is an electron micrograph of the Pickering emulsion of Reference Example 2. An electron micrograph showing a cross section of a coating film of the emulsion of Reference Example 1 and Comparative Example 5 after immersion in seawater. 4 is an electron micrograph showing a cross section of a coating film of the Pickering emulsion of Reference Example 1 before and after immersion in pure water or seawater.

The present invention relates to a pickering emulsion having a visible light transmitting property, comprising an aqueous phase containing a polyol and / or a thickener, an oil phase, and a powder.
Hereinafter, components, compositions, and the like of the pickering emulsion of the present invention will be described in detail.
In the present invention, the pickering emulsion refers to an emulsified composition stabilized using powder. If the powder is an emulsified composition that contributes to emulsion stability, it is referred to as a pickering emulsion even if it contains other surfactants.

The Pickering emulsion of the present invention has visible light transmittance. Here, “having visible light transmittance” means that the transmittance of visible light is not 0% when the optical path length is 1 cm.
The visible light transmittance of the Pickering emulsion of the present invention when the optical path length is 1 cm is preferably 20% or more, more preferably 50% or more, further preferably 70% or more, and further preferably 80% or more.
The Pickering emulsion of the present invention, which contains a polyol and / or a thickener and has a visible light transmission property, is not only excellent in a refreshing appearance but also excellent in water resistance.

The aqueous phase only has to transmit visible light, and its composition is not particularly limited.
In a preferred embodiment of the present invention, the relative refractive index of the water phase to the oil phase is preferably 0.8 to 1.2, more preferably 0.9 to 1.1, and still more preferably 0.95 to 1.05. is there. In particular, it is preferable to make the refractive index of the water phase substantially equal to the refractive index of the oil phase.
By setting the refractive index of the aqueous phase within the above range, it is possible to provide a Pickering emulsion having high transparency and excellent appearance. In addition, the sweat resistance of the pickering emulsion can be improved.
In addition, the relative refractive index of the aqueous phase with respect to the oil phase refers to a numerical value obtained by dividing the refractive index of the aqueous phase by the refractive index of the oil phase.
Although the refractive index of the aqueous phase can be adjusted by adding various additives to the aqueous phase, the content of the polyol and / or the content of the thickener can be adjusted, or the content of the aqueous phase such as sodium chloride or magnesium sulfate can be adjusted. It is preferable to adjust by adding an ionizing salt.

In a preferred embodiment of the present invention, the content of the polyol with respect to the aqueous phase is preferably 30% by mass or more, more preferably 30 to 90% by mass, still more preferably 40 to 80% by mass, and more preferably 50 to 70% by mass. %.
By setting the content of the polyol within the above range, the transparency of the Pickering emulsion and the sweat resistance can be improved.

The content of the polyol in the whole Pickering emulsion is preferably 5% by mass or more, more preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and still more preferably 30 to 50% by mass.
When the content of the polyol is in the above range, the moisture retention of the Pickering emulsion can be improved.

  Polyols include polyethylene glycol, glycerin, 1,3-butylene glycol, erythritol, sorbitol, xylitol, maltitol, propylene glycol, dipropylene glycol, diglycerin, isoprene glycol, 1,2-pentanediol, Examples thereof include xylene glycol, 1,2-hexanediol, and 1,2-octanediol, among which glycerin and 1,3-butylene glycol are preferable.

In a preferred embodiment of the present invention, the content of the thickener with respect to the aqueous phase is preferably 0.1% by mass or more, more preferably 0.1 to 5% by mass, and still more preferably 0.3 to 5% by mass. 2% by mass.
By setting the content of the thickener within the above range, the transparency of the Pickering emulsion and the sweat resistance can be improved.

  The content of the thickener in the whole Pickering emulsion is preferably 0.05% by mass or more, more preferably 0.05 to 5% by mass, and further preferably 0.1 to 1% by mass.

  As thickeners, xanthan gum, gellan gum, guar gum, quince seed, carrageenan, galactan, gum arabic, pectin, mannan, starch, curdlan, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylhydroxypropylcellulose, chondroitin sulfate, dermatan sulfate, Glycogen, heparan sulfate, hyaluronic acid, sodium hyaluronate, tragacanth gum, keratan sulfate, chondroitin, mucoitin sulfate, hydroxyethyl guar gum, carboxymethyl guar gum, dextran, kerato sulfate, locust bean gum, succinoglucan, caronic acid, chitin, chitosan, Carboxymethyl chitin, agar, polyvinyl alcohol, polyvinyl pyrrolidone, carboxyvinyl Limmer, sodium polyacrylate, polyethylene glycol, sodium acrylate graft starch, stearooxyhydroxypropyl methylcellulose, bentonite, etc., more preferably water-soluble polysaccharides such as xanthan gum, guar gum, agar, sodium acrylate graft starch , Stearoxyhydroxypropyl methylcellulose. More preferably, water-soluble polysaccharides such as xanthan gum and guar gum, and agar are preferred.

  The oil agent constituting the oil phase in the Pickering emulsion of the present invention is not particularly limited as long as it has visible light transmittance, and liquid oils and fats, solid oils and fats, waxes, hydrocarbon oils, higher fatty acids, higher alcohols, and ester oils , Silicone oil and the like.

  Examples of liquid fats and oils include avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, southern oil, castor oil, linseed oil , Safflower oil, cottonseed oil, eno oil, meadowfoam oil, soybean oil, peanut oil, teaseed oil, kaya oil, rice bran oil, sinagiri oil, Japanese kiri oil, jojoba oil, germ oil, triglycerin, glycerin trioctanoate, And glycerin triisopalmitate.

  As solid oils and fats, cacao butter, coconut oil, horse fat, hardened coconut oil, palm oil, tallow, sheep butter, hardened tallow, palm kernel oil, lard, beef bone fat, mocro kernel oil, hardened oil, beef leg fat , Molle, hardened castor oil and the like.

  The waxes include beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, ibota wax, whale wax, montan wax, nuka wax, lanolin, kapok wax, lanolin acetate, liquid lanolin, sugar cane wax, lanolin fatty acid isopropyl, hexyl laurate, reduced lanolin, and jojo. Barrow, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, POE hydrogenated lanolin alcohol ether, and the like.

  Examples of the hydrocarbon oil include liquid paraffin, ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax and the like.

  Examples of the higher fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, behenic (beheninic) acid, 12-hydroxystearic acid, undecylenic acid, and tolic acid.

  Examples of the higher alcohol include cetyl alcohol, stearyl alcohol, behenyl alcohol, butyl alcohol, myristyl alcohol, and cetostearyl alcohol.

  As ester oils, isopropyl myristate, cetyl octanoate, octyl dodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyl decyl dimethyloctanoate, cetyl lactate, myristyl lactate, Lanolin acetate, isocetyl stearate, isocetyl isostearate, sucrose stearate, sucrose oleate, cholesteryl 12-hydroxystearate, ethylene glycol di-2-ethylhexylate, fatty acid ester of dipentaerythritol, N-alkyl glycol monoisostearate, dicaprin Neopentyl glycolate, diisostearyl malate, glycerin di-2-heptylundecanoate, tri-2-ethylhexyl Trimethylolpropane luate, trimethylolpropane triisostearate, pentaneerythritol tetra-2-ethylhexylate, glycerin tri-2-ethylhexylate, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate Glyceryl trimmyristate, glyceride tri-2-heptylundecanoate, methyl ester of castor oil fatty acid, oleic acid oil, cetostearyl alcohol, acetoglyceride, 2-heptylundecyl palmitate, cetyl palmitate, diisobutyl adipate, N- Lauroyl-L-glutamic acid-2-octyldodecyl ester, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate Le, myristic acid 2-hexyl decyl palmitate, 2-hexyldecyl, 2-hexyldecyl adipate, sebacic acid diisopropyl, 2-ethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, and triethyl citrate.

  Examples of the silicone oil include chain polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, diphenylsiloxyphenyltrimethicone, pentasiloxane, decamethylpolysiloxane, dodecamethylpolysiloxane, and tetramethyltetrahydrogen. Cyclic polysiloxanes such as genpolysiloxane are exemplified.

  Among them, silicone oil, ester oil, liquid oil and fat, solid oil and fat, and waxes are preferably used, and diphenylpolysiloxane, cetyl ethylhexanoate and the like are particularly preferably used. One or more oil agents can be used.

In the present invention, a powder that can form a Pickering emulsion and has visible light transmittance when the surface is wetted with an oil phase component can be used.
As such a powder, those having the following refractive indexes are preferably mentioned. That is, it is preferable to use a powder having a relative refractive index to the oil phase of preferably 0.7 to 1.3, more preferably 0.8 to 1.2, and still more preferably 0.90 to 1.1. . In particular, it is preferable to use a powder having a refractive index substantially the same as the refractive index of the oil phase.
By using such a powder, it is possible to provide a Pickering emulsion having a high transparency and an excellent refreshing appearance. Further, by using such a powder, the sweat resistance of the pickering emulsion can be improved.
In addition, the relative refractive index of the powder with respect to the oil phase means a numerical value obtained by dividing the refractive index of the powder by the refractive index of the oil phase.

Such powders include, for example, inorganic powders (eg, talc, kaolin, mica, sericite (sericite), muscovite, phlogopite, synthetic mica, biotite, biotite, permiculite, magnesium carbonate, calcium carbonate) , Aluminum silicate, barium silicate, calcium silicate, magnesium silicate, strontium silicate, metal tungstate, magnesium, silica, zeolite, barium sulfate, calcined calcium sulfate (calcined gypsum), calcium phosphate, fluoroapatite, hydroxyapatite , Ceramic powder, etc.), metal soaps (eg, zinc myristate, calcium palmitate, aluminum stearate), boron nitride, titanium dioxide, zinc oxide, iron oxide, etc.); polyacrylic acid and its derivatives, polymethacrylic acid and That Organic polymer powders such as conductors, silicones and derivatives thereof, polyethylene, polypropylene, polyvinyl acetate, vinyl chloride, nylon, polyester, polystyrene, polycarbonate, polyvinyl alcohol, polyoxyethylene, sucrose and derivatives thereof; pearl pigments (for example, , Titanium oxide-coated mica, titanium oxide-coated bismuth oxychloride, titanium oxide-coated talc, colored titanium oxide-coated mica, bismuth oxychloride, fish scale foil, etc.) and may be used alone or in combination of two or more. it can.
Further, a composite powder obtained by coating a powder with a metal oxide or the like, or a powder whose powder surface is treated with a compound or the like may be used.

In the present invention, it is preferable to use a hydrophobized powder whose surface is entirely or partially covered with a hydrophobizing agent.
Here, "the surface of the powder is wholly or partially coated" means not only the state in which the surface of the powder is coated by the hydrophobizing agent being physically attached, but also the powder. It also refers to a state in which a hydrophobic group derived from a hydrophobizing agent is covalently bonded to a functional group exposed on the surface.
When silica or metal oxide is used as the powder, the hydrophobized powder reacts the powder with a hydrophobizing agent, and adds a hydrophobic group to a hydroxyl group present on the surface of the powder by a covalent bond, Further, it can be prepared by coating the surface of the powder by physically attaching a hydrophobizing agent thereto.

When silica fine particles are used as the powder, for example, any of so-called dry silica powder produced by vapor phase oxidation of silicon halide and so-called wet silica powder produced from water glass or the like may be used. .
Examples of dry silica powder include Aerosil series (Nippon Aerosil Co., Ltd.), CAB-O-SIL series (Cabot Corporation), HDK series (Asahi Kasei Wacker Silicone Co., Ltd.), and examples of wet silica powder include Nipsil series (Tosoh Silica). And HI-SIL series (PPG).

The hydrophobizing treatment includes a method of treating a powder with a hydrophobizing agent such as an organosilicon compound, silicone, hydrocarbon oil, fatty acid, fatty acid amide, fatty acid ester, higher alcohol, or polyoxyalkylene compound.
Particularly preferably, the powder is treated using an organosilicon compound or silicone as a hydrophobizing agent.

Examples of the organosilicon compound include hexamethyldisilazane, monomethylsilane, dimethylsilane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, and diphenyldisilane. Ethoxysilane, hexamethyldisiloxane, palmitylsilane and the like can be mentioned. These are used in one kind or in a mixture of two or more kinds.
In a preferred embodiment of the present invention, the powder is treated with trimethylsilane, a hydrophobized powder having a trimethylsilyl group added to the surface is used, and particularly preferably, the silica fine particles are treated with trimethylsilane, and the surface is partially treated. A partially hydrophobized silica to which a trimethylsilyl group is added is used.

  Examples of the silicone include dimethyl silicone, methylphenyl silicone, α-methylstyrene-modified silicone, chlorophenyl silicone, and fluorine-modified silicone.

  When the pickering emulsion is of the oil-in-water type, the M value of the hydrophobized powder is 0 to 9, more preferably 0 to 5, more preferably 0 to 3, still more preferably 0 to 2, and still more preferably 0. ~ 1.

When the Pickering emulsion is a water-in-oil type, the lower limit of the M value of the hydrophobized powder is preferably 0 or more, more preferably 2 or more, still more preferably 5 or more, and still more preferably 15 or more. Can be.
When the pickering emulsion is a water-in-oil type, the upper limit of the M value of the hydrophobized powder is preferably 100 or less, more preferably 80 or less, and further preferably 60 or less.

  The M value is a value indicating the degree of hydrophobicity of the fine particles, and the higher the M value, the higher the hydrophobicity. The M value is represented by the volume ratio of the minimum amount of methanol required for uniformly dispersing the measurement sample in a mixed solution of water and methanol, and can be determined by the following method.

[M value calculation method]
0.2 g of the measurement sample (hydrophobized powder fine particles) is added to 50 mL of water in a 250 mL beaker, and then methanol is gradually dropped from the burette. At this time, the solution in the beaker is constantly stirred with a magnetic stirrer, and the time when the entire amount of the measurement sample is uniformly suspended in the solution is defined as the end point. At this end point, the volume percentage of methanol in the water / methanol mixed solution in the beaker is the M value.
The M value of the hydrophobized powder can be adjusted by its hydrophobization rate. The M value or the hydrophobization rate can be adjusted by appropriately setting the mixing ratio of the powder and the hydrophobizing agent and the treatment time.

Further, it is preferable to use a powder having a charged surface as the hydrophobized powder. The charge on the surface of the hydrophobized powder may be either positive or negative, but is preferably negative.
In this case, the hydrophobized powder only needs to be charged at least in an emulsified state, that is, in a state of being in contact with water, and need not have a charge before the preparation of the emulsion.

  Examples of the hydrophobic powder having a charged surface include silica, and those obtained by hydrophobizing metal oxides such as titanium oxide, zinc oxide and iron oxide, particularly preferably those obtained by partially hydrophobizing. . Silica powder is negatively charged in water, and metal oxides are positively and negatively charged in water.

  The average primary particle diameter of the powder can be about 1 to 1000 nm, preferably 3 to 100 nm, more preferably 5 to 30 nm.

The average secondary particle diameter of the powder can be preferably about 1 μm or less, preferably 500 nm or less, more preferably 200 nm or less, and further preferably 50 nm or less.
When the average secondary particle size is in the above range, the emulsified particle size can be made smaller, the degree of aggregation of the coating film after contact with the aqueous solution containing ions can be improved, and the resistance to the aqueous solution can be further improved. Can be enhanced.

  Further, by setting the average secondary particle diameter in the above range, the emulsion particle diameter can be further reduced, and the emulsion stability can be improved.

Here, the average primary particle diameter and the average secondary particle diameter can be determined by measuring the maximum diameter of 2500 or more particles on a scanning electron microscope image and calculating the number average.
The average secondary particle diameter can be adjusted by the stress applied to the composition when emulsifying.

  In a preferred embodiment of the present invention, the content of the powder is preferably from 0.3 to 5.0% by mass, more preferably from 0.4 to 4.0% by mass, and still more preferably from 0 to 4.0% by mass, based on the whole emulsion. It can be set to 0.5 to 3.0% by mass, particularly preferably 1.0 to 2.0% by mass.

  In a preferred embodiment of the present invention, the viscosity at 25 ° C. and 1 atm is preferably 4000 mPa · s or more, more preferably 4000 to 100000 mPa · s. The viscosity may be measured, for example, by using a cone plate type viscometer (apparatus model name: RE-80R, manufacturer name: Toki Sangyo, condition: rotor: 3 ° × R14, measurement temperature: 25 ° C., rotation speed: 50 rpm, measurement time) : 3 minutes).

In the Pickering emulsion of the present invention, optional components usually used in cosmetics can be contained in addition to the above components within a range that does not impair the effects of the present invention. Such optional components include, for example, anionic surfactants such as fatty acid soaps (sodium laurate, sodium palmitate, etc.), potassium lauryl sulfate, triethanolamine ether alkyl sulfate, stearyltrimethylammonium chloride, benzalkonium chloride, lauryl Cationic surfactants such as amine oxides, imidazoline-based amphoteric surfactants (eg, 2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt), betaine-based surfactants (alkyl betaines, amides) Amphoteric surfactants such as betaine and sulfobetaine), acylmethyltaurine, sorbitan fatty acid esters (sorbitan monostearate, sorbitan sesquioleate, etc.), and glycerin fatty acids (glycosyl monostearate) Phosphorus), propylene glycol fatty acid esters (propylene glycol monostearate, etc.), hydrogenated castor oil derivatives, glycerin alkyl ether, POE sorbitan fatty acid esters (POE sorbitan monooleate, polyoxyethylene sorbitan monostearate, etc.), POE Sorbite fatty acid esters (such as POE-sorbitol monolaurate), POE glycerin fatty acid esters (such as POE-glycerin monoisostearate), POE fatty acid esters (such as polyethylene glycol monooleate and POE distearate), and POE alkyl ethers ( POE2-octyldodecyl ether, etc.), POE alkyl phenyl ethers (POE nonyl phenyl ether, etc.), pluronic type, POE / POP alkyl ether Nonionic interfaces such as ters (POE / POP2-decyltetradecyl ether, etc.), tetronics, POE castor oil / hardened castor oil derivatives (POE castor oil, POE hardened castor oil, etc.), sucrose fatty acid esters, alkyl glucosides, etc. Activators, moisturizing ingredients such as sodium pyrrolidonecarboxylate, lactic acid, sodium lactate, etc., which may be surface-treated, mica, talc, kaolin, synthetic mica, calcium carbonate, magnesium carbonate, silicic anhydride (silica), oxidized Composites of powders such as aluminum and barium sulfate, which may be surface-treated, inorganic pigments such as cobalt oxide, ultramarine, navy blue, and zinc oxide, and which may be surface-treated, and iron oxide titanium dioxide sintered bodies Pigment, pearling agents such as titanium mica, fish phosphor foil, bismuth oxychloride, which may be surface-treated, Red # 202, Red # 228, Red # 226, Yellow # 4, Blue # 404, Yellow # 5, Red # 505, Red # 230, Red # 223, Orange # 201, Red # 213 which may be chelated And organic powders such as yellow 204, yellow 203, blue 1, green 201, purple 201, and red 204, polyethylene powder, polymethyl methacrylate, nylon powder, and organopolysiloxane elastomer. , Lower alcohols such as ethanol and isopropanol, vitamin A or a derivative thereof, vitamin B ₆ hydrochloride, vitamin B ₆ tripalmitate, vitamin B ₆ dioctanoate, vitamin B ₂ or a derivative thereof, vitamin B ₁₂ , vitamin B ₁₅ or B vitamins such as derivatives thereof, α-tocopherol, β-tocopherol, γ-tocophero , Vitamin E such as vitamin E acetate, vitamin D, vitamin H, pantothenic acid, pantethine, vitamins such as pyrroloquinoline quinone, paraaminobenzoic acid, paraaminobenzoic acid monoglycerin ester, N, N-dipropoxyparaamino acid Ethyl benzoate, ethyl N, N-diethoxyparaaminobenzoate, ethyl N, N-dimethylparaaminobenzoate, butyl N, N-dimethylparaaminobenzoate, ethyl N, N-dimethylparaaminobenzoate, Benzoic acid derivatives such as hexyl diethylaminohydroxybenzoyl benzoate; anthranilic acid derivatives such as homomenthyl-N-acetylanthranilate; salicylic acid and its sodium salt, amyl salicylate, menthyl salicylate, homo Salicylic acid derivatives such as ethyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, p-isopropanol phenyl salicylate; octyl cinnamate, ethyl-4-isopropyl cinnamate, methyl-2,5-diisopropyl cinnamate, ethyl-2,4 -Diisopropylcinnamate, methyl-2,4-diisopropylcinnamate, propyl-p-methoxycinnamate, isopropyl-p-methoxycinnamate, isoamyl-p-methoxycinnamate, 2-ethylhexyl p-methoxycinnamate (methoxysilicate Ethylhexyl cinnamate, octyl paramethoxycinnamate), 2-ethoxyethyl-p-methoxycinnamate (cinoxate), cyclohexyl-p-methoxycinnamate Ethyl-α-cyano-β-phenylcinnamate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate (octocrylene), glyceryl mono-2-ethylhexanoyl-diparamethoxycinnamate, ferulic acid and derivatives thereof Cinnamic acid derivatives such as 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4' -Tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone (oxybenzone-3), 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4- Phenylbenzophenone, 2-ethylhexyl-4 ' Benzophenone derivatives such as phenyl-benzophenone-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'-methylphenylbenzotriazole;dibenzalazine;dianisoylmethane; 5- (3,3-dimethyl-2-norbornylidene) -3-pentan-2-one; 4- Dibenzoylmethane derivatives such as t-butylmethoxydibenzoylmethane Octyl triazone; urocanic acid derivatives such as urocanic acid and ethyl urocanate; 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 1- (3,4-dimethoxyphenyl) -4,4-dimethyl Hydantoin derivatives such as -1,3-pentanedione, dimethoxybenzylidene dioxoimidazolidinyl 2-ethylhexyl propionate; phenylbenzimidazole sulfonic acid, terephthalidene dicanfursulfonic acid, drometrizole trisiloxane, methyl anthranilate, Preferred examples include ultraviolet absorbers such as bisethylhexyloxyphenol methoxyphenyl triazine, rutin and its derivatives, and oryzanol and its derivatives.

  As described above, the pickering emulsion of the present invention may use a surfactant, but the content thereof is preferably as small as possible. The content of the surfactant is preferably 5% by mass or less, more preferably 1% by mass or less, further preferably 0.1% by mass or less, and particularly preferably 0% by mass.

The Pickering emulsion of the present invention is suitable for a skin external preparation. In particular, it is preferable to make use of the function of an ultraviolet absorber to make a sunscreen skin external preparation.
Especially, it is preferable to use it for cosmetics, and it is preferable to use it as a sunscreen, a makeup base, etc.

In the following examples, partially hydrophobized silica was used as the hydrophobized powder. The partially hydrophobized silica used was obtained by mixing silica fine particles (manufactured by AEROSIL, having an average primary particle diameter of 12 nm (the measuring method is as described above)) and a trimethylsilyl hydrophobizing agent. When the M value of the partially hydrophobized silica was measured by the method described above, it was 0.
At room temperature (25 ° C.), (b) an emulsifying component (partially hydrophobized silica or a surfactant) is dispersed in (a) an aqueous phase component shown in Table 1, and (c) an oil phase component is stirred therein. The oil-in-water emulsified compositions of Examples and Comparative Examples were produced by charging and emulsifying.

The emulsified compositions of Example 1, Comparative Examples 1 and 2 could be produced by the above-described method. However, an emulsion composition having the formulation of Comparative Example 3 could not be produced by the above production method.
This result indicates that when the aqueous phase contains a large amount of polyol, it is preferable to form a Pickering emulsion emulsified with a powder instead of a surfactant.

  In addition, the viscosities of the compositions of Examples and Comparative Examples were measured. Table 1 shows the results. The viscosity was measured using a cone-plate viscometer (apparatus model: RE-80R, manufacturer: Toki Sangyo, condition: rotor: 3 ° × R14, measurement temperature: 25 ° C., rotation speed: 50 rpm, measurement time: 3 minutes).

  The following tests were performed on the emulsified compositions of Example 1 and Comparative Examples 1 and 2 that could be manufactured.

<Test Example 1> Evaluation of sweat resistance The sweat resistance of the emulsified compositions of Example 1, Comparative Examples 1 and 2 was evaluated by the following method. Each composition was uniformly applied to a 50 mm × 50 mm polymethyl methacrylate resin (PMMA) plate so as to have a concentration of 0.2 g / cm ^2, and the SPF value was measured using an SPF Analyzer System UV-2000S (manufactured by Labsphere). did. Subsequently, the PMMA plate was immersed in artificial sweat, stirred at 150 rpm for 2 hours, taken out of water, and measured for SPF in the same manner.
The value obtained by dividing the SPF value after immersion by the SPF value before immersion was defined as the residual ratio (%) of the SPF value, which was used as an index of sweat resistance. Table 2 shows the results.

<Test Example 2> Evaluation of high-temperature stability The emulsion compositions of Example 1, Comparative Examples 1 and 2 were evaluated for emulsion stability at high temperature by the following method.
After the preparation, the mixture was allowed to stand at 20 ° C. for 24 hours, and then the emulsion particle size was measured (initial emulsion particle size). The emulsified particle diameter was determined by calculating the number average of the maximum diameter of 10 emulsified particles observed at 20 ° C at a magnification of 400 times (10 times eyepiece-40 times objective) with an optical microscope OLYMPUS BX51. Subsequently, after storing the emulsified composition at 40 ° C. for one week, the average particle size (particle size after storage) of the oil phase in the emulsified composition was measured by the same method. As a result, those having a particle size of 2 times or more as compared with the initial particle size after storage were evaluated as x, those having a particle size of 1.5 to 2.0 times Δ, those having a particle size of 1.5 times or less as Δ As shown in Table 2.
Further, the viscosity of the prepared emulsion composition after leaving it at 40 ° C. for one month was measured by the above-described method. The results are shown in Table 2.

<Test Example 3> Evaluation of transparency The visible light transmittance of each of the emulsified compositions of Example 1, Comparative Examples 1 and 2 was measured. The visible light transmittance was set to a visible light transmittance of 400 to 800 nm generally called visible light using an ultraviolet / visible spectrophotometer V660 (JASCO). Table 2 shows the results.

<Test Example 4> Evaluation of apparent coolness The emulsified compositions of Example 1, Comparative Examples 1 and 2 were subjected to a sensory evaluation of the apparent coolness and moisture retention. The evaluation was performed by 10 skilled researchers engaged in sensory evaluation of cosmetics, and each evaluation item was evaluated on a scale of 5 out of the following criteria, and the average score was used as the evaluation score of each evaluation item. By doing that. Table 2 shows the results.

(Look cool)
5 points: A very strong refreshing feeling is felt.
4 points: Feel cool.
3 points: Feel cool but weak.
2 points: I finally feel the refreshing feeling.
1 point: I don't feel cool.

(Moisturizing)
5 points: Very moist after a certain time after application.
4 points: Moist after a certain period of time after application.
3 points: After applying for a certain period of time, the skin feels a little dry.
2 points: A feeling of dryness is felt after a certain period of time after application.
1 point: After coating, a certain feeling of dryness is noticeable after a certain period of time.

The Pickering emulsion of Example 1 containing a total of 40% by mass of the polyol (62.5% by mass with respect to the aqueous phase) has visible light transmittance, but the total of 15% by mass of the polyol with respect to the aqueous phase (based on the aqueous phase). The pickering emulsion of Comparative Example 1 containing only 23% by mass and the emulsified composition of Comparative Example 2 do not have visible light transmittance.
This result is considered to be due to the fact that the aqueous phase of the Pickering emulsion of Example 1 had a refractive index changed by having a large amount of polyol, and was almost the same as the relative refractive index to the oil phase. .
As described above, an emulsified composition could not be formed by the formulation of Comparative Example 3 containing the polyol at the same content as in Example 1.
As described above, in order to form an emulsified composition having a visible light transmittance, it is preferable to form a Pickering emulsion emulsified with a powder.

In addition, the emulsified composition of Comparative Example 2 emulsified with a surfactant shows an increase in the emulsified particle size by storage at a high temperature, while the emulsified compositions of Example 1 and Comparative Example 1 which are Pickering emulsions Has a low degree of increase in the emulsion particle diameter (Table 2).
Furthermore, comparing the viscosity of the emulsified composition immediately after preparation described in Table 1 with the viscosity of the emulsified composition after being left at 40 ° C. for one month shown in Table 2, the comparison shows that the emulsion is emulsified by a surfactant. The viscosity of the emulsified composition of Example 2 was markedly reduced, while the viscosity of the pickling emulsions of Example 1 and Comparative Example 1 was not significantly reduced.
This result shows that from the viewpoint of high-temperature stability, it is preferable to form a Pickering emulsion emulsified with a powder in order to form an emulsion composition having visible light transmittance.

Further, the Pickering emulsion of Example 1 having transparency and having an excellent refreshing sensation is superior in sweat resistance to the Pickering emulsion of Comparative Example 1 having no permeability and having an inferior cooling sensation. (Table 2).
This result indicates that the pickering emulsion of the present invention having permeability is excellent not only in a refreshing appearance but also in sweat resistance.

<Test Example 5> Surface potential of partially hydrophobized silica Silica fine particles (manufactured by AEROSIL, average primary particle diameter 12 nm (measurement method is as described above), hereinafter also referred to as untreated silica), and the silica fine particles and trimethylsilyl hydrophobic A partially hydrophobized silica obtained by mixing a hydrophobizing agent was prepared.

This partially hydrophobized silica is dispersed in pure water or seawater (artificial seawater, GEX) at a concentration of 0.001 g / mL, and its zeta potential is measured by a zeta potential analyzer (ELS-Z, Otsuka Electronics). It was measured.
As a result, the zeta potential of the partially hydrophobized silica when dispersed in pure water and seawater was 16.84 ± 2.18 mV and 4.16 ± 1.26 mV, respectively (FIG. 1).

  This result indicates that partially hydrophobized silica has a surface charge in an environment where ions are not present, but becomes hydrophobic by neutralizing its surface charge in the presence of ions. It is shown that.

<Test Example 6> Seawater resistance test Using the partially hydrophobized silica used in Test Example 5, oil-in-water emulsions of Reference Example 1 and Comparative Example 4 were prepared according to the formulations shown in Table 3.

The emulsions of Reference Example 1 and Comparative Example 4 were applied on a PMMA plate at a rate of 2.0 mg / cm ² , and the plate was immersed in 150 mL of seawater, using a stirrer at 150 rpm and 25 ° C. Stirring was performed for 2 hours. Thereafter, the amount of ethylhexylmethoxycinnamate eluted in seawater was measured using HPLC.

  As a result, the amount of ethylhexyl methoxycinnamate dissolved in seawater from the plate on which the emulsion of Comparative Example 4 was applied was 1,327 μg. On the other hand, the amount of ethylhexyl methoxycinnamate dissolved in seawater from the plate on which the emulsion of Reference Example 1 was applied was 113.9 μg, which was 1/11 of the elution amount in the emulsion of Comparative Example 4 (FIG. 2).

  This result indicates that the Pickering emulsion emulsified with partially hydrophobic silica having a surface charge in pure water has excellent resistance to an aqueous solution containing ions.

<Test Example 7> Observation of cross section of coating film (1)
The state of the cross section of the coating film of the emulsion of Reference Example 1 and Comparative Example 4 formed on the PMMA plate before and after immersion in seawater by the method of Test Example 6 was observed by a scanning electron microscope (SEM) (FIG. 3). .

  As shown in FIG. 3, most of the coating film of the emulsion of Comparative Example 4 was peeled off by immersion in seawater. On the other hand, the coating film of the emulsion of Reference Example 1 was maintained on the plate even after immersion in seawater.

  The results of Test Examples 5 to 7 indicate that the emulsion of Reference Example 1 was exposed to an aqueous solution containing ions, and the partially hydrophobized silica, which had lost its surface charge and became hydrophobic, was agglomerated. This indicates that the particles themselves aggregate and the physical strength is improved.

<Test Example 8> Measurement of SPF Before and after immersion in seawater in the same manner as in Test Example 6, the SPF values of the coating films of the emulsions of Reference Example 1 and Comparative Example 4 applied on a PMMA plate were measured with an SPF analyzer. It was measured.

  As a result, the SPF value of the coating film of the emulsion of Comparative Example 4 was reduced to 70% after immersion in seawater. On the other hand, the coating film of the emulsion of Reference Example 1 surprisingly improved the SPF value to 140% after immersion in seawater (FIG. 4).

<Test Example 9> Measurement of scattering rate The emulsion of Reference Example 1 was applied to a quartz plate so as to have a constant thickness, and the scattering rate of light in an ultraviolet region before and after contact with seawater was measured using a spectrophotometer (V- 600, JASCO).
As a result, the coating film of the emulsion of Reference Example 1 surprisingly increased the light scattering rate in the ultraviolet region after contact with seawater (FIG. 5).

  Considering the results of Test Example 5, the results of Test Example 9 show that after exposure to an aqueous solution containing ions, the partially hydrophobized silica that has become hydrophobic due to loss of surface charge is aggregated, and the scattering rate of ultraviolet rays is increased. Has increased.

  When considered in conjunction with the results of Test Example 9, the results of Test Example 8 show that the light path length in the coating film increases due to the increase in the scattering rate of ultraviolet light after touching the aqueous solution containing ions. This shows that the ultraviolet absorbing efficiency of the ultraviolet absorber (ethylhexyl methoxycinnamate) was improved.

  The results of Test Examples 5 to 9 show that the Pickering emulsion of the present invention has excellent resistance to an aqueous solution containing ions.

<Test Example 10> Observation by Electron Microscope The oil-in-water picker of Reference Example 2 prepared according to the formulation shown in Table 4 using partially hydrophobized silica treated with a trimethylsilyl hydrophobizing agent in the same manner as in Test Example 1. The ring emulsion was observed with a scanning electron microscope. An electron microscope image is shown in FIG.

The secondary particle diameter of the partially hydrophobized silica in the Pickering emulsion of Reference Example 2 was calculated based on FIG. As a result, the average secondary particle diameter of the silica was 50 nm or less.
The Pickering emulsions of Reference Example 2 and Example were produced by the same method using common partially hydrophobized silica. Therefore, from the result of observation of the Pickering emulsion of Reference Example 2 with a scanning electron microscope, it can be inferred that the average secondary particle diameter of silica in the Pickering emulsion of Example is also 50 nm or less.

<Test Example 11> Observation of cross section of coating film (2)
Using the partially hydrophobized silica treated with the trimethylsilyl hydrophobizing agent in the same manner as in Test Example 1, an emulsion of Comparative Example 5 having the formulation shown in Table 5 was prepared. The emulsion of Comparative Example 5 and Reference Example 1 prepared above was immersed in seawater in the same manner as in Test Example 6. Thereafter, as in Test Example 7, a cross-sectional view of the coating film of the emulsion after immersion was observed with a scanning electron microscope. An electron microscope image is shown in FIG.

As shown in Table 5, the emulsion of Comparative Example 5 contained a surfactant (PEG-25 stearate) in an amount sufficient to maintain an emulsified system. Therefore, in the emulsion of Comparative Example 5, the partially hydrophobized silica is not adsorbed on the interface between the aqueous phase and the oil phase, but is dispersed in the aqueous phase by the action of the surfactant. That is, the emulsion of Comparative Example 5 is not a Pickering emulsion.
Therefore, when the coating film of the emulsion of Comparative Example 5 is brought into contact with seawater, the partially hydrophobized silica dispersed in the aqueous phase forms an aggregate (a portion surrounded by a dotted line in FIG. 7), but the entire coating film is formed. Did not occur (FIG. 7).

  This result indicates that the effect of the present invention cannot be obtained with an emulsion in which an emulsified powder whose surface is charged is simply dispersed.

On the other hand, Reference Example 1 is a Pickering emulsion in which the partially hydrophobized silica is adsorbed on the interface between the water phase and the oil phase, whereby the emulsified state is stabilized.
Then, the coating film of the Pickering emulsion of Reference Example 1 is condensed and hydrophobicized by the aggregation of the emulsified droplets on which the partially hydrophobized silica is adsorbed at the interface after contact with seawater (FIG. 7).

  The above results show that the effect of the present invention of excellent resistance to an aqueous solution containing ions is brought about by a form of a pickering emulsion stabilized by an emulsified powder having a charged surface. I have.

<Test Example 8> Observation of cross section of coating film (3)
The coating film of the Pickering emulsion of Reference Example 1 was immersed in pure water and seawater in the same manner as in Test Example 6. FIG. 8 shows electron microscope images of the cross section of the coating film before and after immersion in pure water or seawater.

As shown in FIG. 8, the coating film of the Pickering emulsion of Reference Example 1 did not peel off after immersion in not only seawater but also pure water, and the porous structure was maintained.
This result indicates that the coating film of the Pickering emulsion of the present invention has excellent water resistance.

Further, in the coating film of the Pickering emulsion of Reference Example 1, the thickness of the film partitioning the pores in the porous structure appearing in the cross section by immersion in seawater is about three times.
This result indicates that the coating film of the Pickering emulsion of the present invention is highly agglomerated by contact with an aqueous solution containing ions, thereby increasing the hydrophobicity of the entire film.

  The present invention is suitable for cosmetics.

Claims (7)

  A pickling emulsion having visible light transmittance, comprising a water phase containing a polyol and / or a thickener, an oil phase, and a powder.   The pickering emulsion according to claim 1, wherein a relative refractive index of the powder to the oil phase is 0.7 to 1.3.   The Pickering emulsion according to claim 1, wherein a relative refractive index of the water phase to the oil phase is 0.8 to 1.2.   The Pickering emulsion according to any one of claims 1 to 3, further comprising 30% by mass or more of a polyol based on the aqueous phase.   The pickering emulsion according to any one of claims 1 to 4, further comprising 0.1% by mass or more of a thickener based on the aqueous phase.   The pickering emulsion according to any one of claims 1 to 5, wherein the viscosity at 25 ° C and 1 atm is 4000 mPa · s or more. The pickering emulsion according to any one of claims 1 to 6, wherein the powder is a partially hydrophobized powder whose surface is partially coated with a hydrophobizing agent.