W / O type Pickering emulsion and cosmetic containing same

Abstract

To provide a W / O Pickering emulsion that can effectively inhibit the aggregation of emulsion drops over time.SOLUTION: A W / O Pickering emulsion contains aqueous phase, oil phase, and hydrophobic powder, the W / O Pickering emulsion containing magnesium sulfate and / or organic acid salt.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a W / O type Pickering emulsion and a cosmetic preparation containing the same. [Background technology]

[0002] In recent years, the use of W / O type Pickering emulsions has been attracting attention in the field of cosmetics (Patent Document 1).

[0003] Here, Patent Document 1 discloses that by combining and blending a hydrophobic powder with a hydrophilic surfactant, it is possible to provide a water-in-oil emulsion composition that exhibits excellent emulsion stability and no sticky feeling. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5477883 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above-mentioned prior art, an object of the present invention is to provide a technology for designing a W / O type Pickering emulsion that has the effect of inhibiting the coalescence of emulsified droplets over time. [Means for solving the problem]

[0006] That is, the present invention, which solves the above problems, A W / O type Pickering emulsion comprising an aqueous phase, an oil phase, and a hydrophobized powder, The W / O type Pickering emulsion contains magnesium sulfate and / or an organic acid salt. It is a W / O type Pickering emulsion. By adopting the above-mentioned form, it is possible to provide a W / O type Pickering emulsion that has the effect of inhibiting coalescence of emulsified droplets over time.

[0007] In a preferred embodiment of the present invention, the content ratio of magnesium sulfate and / or organic acid salt to hydrophobic powder is within the range of 1:0.2 to 1:100. By adopting the above-mentioned form, it is possible to provide a W / O type Pickering emulsion that has the effect of inhibiting coalescence of emulsified droplets over time.

[0008] In a preferred embodiment of the present invention, the hydrophobic powder is silica silylate.

[0009] In a preferred embodiment of the present invention, the content of magnesium sulfate and / or organic acid salt is 0.1% by mass or more.

[0010] In a preferred embodiment of the present invention, the oil phase contains 40 mass % or more of a volatile oil based on the total amount of oils contained in the oil phase.

[0011] The present invention, which solves the above-mentioned problems, also provides a cosmetic preparation containing the above-mentioned W / O type Pickering emulsion.

[0012] In a preferred embodiment of the present invention, the cosmetic is a foundation or a sunscreen.

[0013] The present invention also provides a method for producing a W / O type Pickering emulsion containing an aqueous phase, an oil phase, and a hydrophobized powder, the method comprising: The method comprises the steps of preparing an aqueous phase and preparing an oil phase, The method for producing a W / O type Pickering emulsion is also characterized in that the aqueous phase contains magnesium sulfate and / or an organic acid salt. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a W / O type Pickering emulsion that has the effect of inhibiting the coalescence of emulsified droplets over time. DETAILED DESCRIPTION OF THE INVENTION

[0015] <1> W / O type Pickering emulsion The present invention is a W / O type Pickering emulsion in which an aqueous phase and an oil phase are emulsified by a hydrophobized powder. The present invention is characterized by containing magnesium sulfate and / or an organic acid salt.

[0016] In this specification, W / O type Pickering emulsion refers to a water-in-oil (W / O type) emulsion produced using fine particles (hydrophobized powder in this specification) that act as emulsifiers by adsorbing to the interface between the oil phase and the aqueous phase.

[0017] As will be shown in the examples below, the W / O type Pickering emulsion of the present invention may contain a surfactant, but the content thereof is preferably kept as low as possible, preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0% by mass. According to the present invention, it is possible to provide a W / O type Pickering emulsion that has the effect of inhibiting the coalescence of emulsified droplets over time, even when the surfactant content is below the upper limit.

[0018] The W / O type Pickering emulsion of the present invention is suitable for use as an external preparation for the skin. In particular, the W / O type Pickering emulsion of the present invention is preferably used in cosmetics. Preferred examples of the cosmetic preparation include sunscreens, sunblocks, makeup bases, and foundations. Here, as the foundation, a liquid foundation can be particularly preferably mentioned.

[0019] The components contained in the W / O type Pickering emulsion of the present invention will be described in detail below.

[0020] (1) Hydrophobic powder In this specification, the hydrophobic powder refers to fine particles that act as an emulsifier by adsorbing to the interface between an oil phase and an aqueous phase.

[0021] The fine particles used in this specification may be any of inorganic powders such as silica, titanium dioxide, tin oxide, clay minerals, aluminum oxide, nanoparticulate precipitated calcium carbonate, coal, magnesium oxide, and magnesium trisilicate, and organic powders such as resin particles of ethyl cellulose, crystalline fatty alcohols and fatty acids, polystyrene, polymethyl methacrylate (PMMA), and the like.

[0022] It is also preferable that the surfaces of the above-mentioned fine particles are subjected to a hydrophobic treatment. In the present invention, it is also possible to use partially hydrophobicized powders in which the surfaces of fine particles are partially hydrophobicized.

[0023] Examples of hydrophobic treatment include methods of treating the powder with a hydrophobic treatment agent such as an organosilicon compound, silicone, hydrocarbon oil, fatty acid, fatty acid amide, fatty acid ester, higher alcohol, or polyoxyalkylene compound. In particular, the hydrophobic treatment of the fine particles is preferably carried out in a form in which the powder is treated using an organosilicon compound or silicone as a hydrophobic treatment agent.

[0024] Examples of the organosilicon compound include hexamethyldisilazane, monomethylsilane, dimethylsilane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, and palmitylsilane.

[0025] Examples of silicones include dimethyl silicone, methylphenyl silicone, α-methylstyrene-modified silicone, chlorophenyl silicone, and fluorine-modified silicone.

[0026] The hydrophobic treatment agent may be used alone or in combination of two or more.

[0027] In the present invention, it is preferable to use silica silylate and / or titanium oxide treated with hydrogen dimethicone as the hydrophobic powder. Among these, it is preferable to use silica silylate in the present invention.

[0028] The particle size of the hydrophobized powder is preferably an average primary particle size of 200 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, even more preferably 30 nm or less, and particularly preferably 15 nm or less. By setting the particle size of the hydrophobized powder within the above range, it is possible to more reliably produce a W / O type Pickering emulsion. By adjusting the particle size of the hydrophobized powder to fall within the above range, the emulsion particles can be adjusted to be small, and the stability of the preparation is improved.

[0029] In the present invention, the average primary particle size is not particularly limited and means the size of primary particles measured by a method generally used for particles. Specifically, the average primary particle size can be the arithmetic mean value of the major and minor axes of the particles obtained from a transmission electron microscope photograph.

[0030] The content of the hydrophobic powder is preferably 0.3 mass% or more, more preferably 0.4 mass% or more, more preferably 0.5 mass% or more, even more preferably 0.7 mass% or more, and particularly preferably 0.9 mass% or more, based on the total amount of the W / O type Pickering emulsion.

[0031] Furthermore, the content of the hydrophobic powder is preferably 5% by mass or less, more preferably 4% by mass or less, more preferably 3% by mass or less, particularly preferably 2.5% by mass or less, and particularly preferably 2% by mass or less, based on the total amount of the W / O type Pickering emulsion.

[0032] The content of the hydrophobic powder is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, per 10 parts by mass of water. The content of the hydrophobic powder is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, even more preferably 1 part by mass or less, and particularly preferably 0.5 parts by mass or less, per 10 parts by mass of water.

[0033] The content of the hydrophobic powder is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and particularly preferably 0.2 parts by mass or more, per 10 parts by mass of the oil agent.

[0034] The content of the hydrophobized powder is preferably 1 part by mass or less, more preferably 0.8 parts by mass or less, per 10 parts by mass of the oil agent. By setting the content of the hydrophobized powder within the above range, it is possible to provide a W / O type Pickering emulsion that has the effect of inhibiting coalescence of emulsified droplets over time.

[0035] (2) magnesium sulfate and / or organic acid salts and / or organic acid salts The present invention is characterized by using magnesium sulfate and / or an organic acid salt.

[0036] The content of magnesium sulfate and / or organic acid salt is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, more preferably 0.1 mass% or more, even more preferably 0.2 mass% or more, and particularly preferably 0.3 mass% or more, based on the total amount of the W / O type Pickering emulsion.

[0037] Furthermore, the content of magnesium sulfate and / or organic acid salt is preferably 1.5% by mass or less, more preferably 1.2% by mass or less, more preferably 1% by mass or less, even more preferably 0.8% by mass or less, and particularly preferably 0.6% by mass or less, based on the total amount of the W / O type Pickering emulsion.

[0038] The content ratio of magnesium sulfate and / or organic acid salt to hydrophobic powder is preferably within the range of 1:0.2 to 1:100, more preferably 1:0.5 to 1:50, more preferably 1:1 to 1:25, and even more preferably 1:2 to 1:10.

[0039] In the present invention, it is preferable that magnesium sulfate and / or an organic acid salt is contained in the aqueous phase.

[0040] By setting the content of magnesium sulfate and / or organic acid salt within the above range, it is possible to provide a W / O type Pickering emulsion that has the effect of inhibiting coalescence of emulsified droplets over time.

[0041] Examples of organic acid salts include acetate, lactate, malate, citrate, and succinate. Specific examples of organic acid salts include sodium acetate, potassium acetate, sodium lactate, potassium lactate, aluminum lactate, sodium malate, potassium malate, potassium citrate, sodium citrate, sodium succinate, and potassium succinate.

[0042] Here, the organic acid salt used in the present invention is preferably a citrate salt. Of these, the organic acid salt is preferably sodium citrate. By using sodium citrate, it is possible to provide a W / O type Pickering emulsion that has the effect of suppressing the coalescence of emulsified droplets over time.

[0043] (3) Oil phase components The W / O type Pickering emulsion of the present invention contains an oil as an oil phase component. The content of the oil is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, based on the total amount of the W / O type Pickering emulsion.

[0044] The content of the oil is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less, based on the total amount of the W / O type Pickering emulsion.

[0045] The W / O type Pickering emulsion of the present invention preferably contains both a volatile oil and a non-volatile oil.

[0046] (3-1) Non-volatile oil A more preferred embodiment of the non-volatile oil used in the W / O type Pickering emulsion of the present invention will be described below.

[0047] Examples of the non-volatile oil agent used in the present invention include liquid oils and fats, solid oils and fats, waxes, hydrocarbon oils, higher fatty acids, higher alcohols, ester oils, and silicone oils.

[0048] The W / O type Pickering emulsion of the present invention preferably contains a non-volatile oil having an IOB value of preferably 0.2 or more, more preferably 0.25 or more. When such highly polar oils are used, it has been difficult to prepare stable W / O type Pickering emulsions using conventional methods. According to the present invention, even when a non-volatile oil having the above IOB value is used, a W / O type Pickering emulsion having excellent emulsion stability can be prepared.

[0049] Here, the non-volatile oil having the above IOB value is preferably one or more oils selected from liquid oils, solid oils, waxes, hydrocarbon oils, higher fatty acids, higher alcohols, and ester oils.

[0050] The content of the non-volatile oil having the above IOB value is preferably 0.8% by mass or more, more preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 8% by mass or more, based on the total amount of the W / O type Pickering emulsion.

[0051] Furthermore, the content of the non-volatile oil having the above IOB value is preferably 50% by mass or less, more preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less, based on the total amount of the W / O type Pickering emulsion.

[0052] Furthermore, the mass ratio of the hydrophobic powder to the non-volatile oil having IOB within the above range is preferably within the range of 1:0.5 to 1:40, more preferably 1:1 to 1:30, more preferably 1:1.5 to 1:20, and even more preferably 1:2 to 1:10.

[0053] By setting the content of the non-volatile oil within the above range, it is possible to provide a W / O type Pickering emulsion that has the effect of inhibiting the coalescence of emulsified droplets over time.

[0054] The non-volatile oils are propylene glycol isostearate (IOB value: 0.4), diethylhexyl sebacate (IOB value: 0.24), 2-ethylhexyl para-methoxycinnamate (IOB value: 0.28), trimethylpropane tri-2-ethylhexanoate (IOB value: 0.31), di-2-ethylhexyl succinate (IOB value: 0.32), propylene glycol dicaprylate / caprate (IOB value: 0.32), 2-ethylhexyl 2-cyano-3,3-diphenylacrylate (IOB value: 0.33), and tricaprylate / caprate glyceryl. (IOB value: 0.33), Trimethylolpropane Trioctanoate (IOB value: 0.33), Glyceryl Tricaprylate (IOB value: 0.33), Ethylene Glycol Dioctanoate (IOB value: 0.35), Glyceryl Dimyristate (IOB value: 0.35), Diethylene Glycol Dilaurate (IOB value: 0.35), Pentaerythrityl Tetra-2-Ethylhexanoate (IOB value: 0.35), Glyceryl Monostearate Diacetate (IOB value: 0.36), Propylene Glycol Monostearate (IOB value: 0.38), Propylene Glycol Oleate Cocoa (IOB value: 0.39), oleyl lactate (IOB value: 0.39), propylene glycol dicaproate (IOB value: 0.4), ethylene glycol monostearate (IOB value: 0.4), diethylene glycol dicaprate (IOB value: 0.41), glyceryl dicocoate (IOB value: 0.41), glyceryl dilaurate (IOB value: 0.41), glyceryl sesquioleate (IOB value: 0.41), ethylene glycol monooleate (IOB value: 0.41), coconut alcohol (IOB value: 0.42), lauryl alcohol (IOB value: 0.41) OB value: 0.42), cetyl lactate (IOB value: 0.42), diethyl sebacate (IOB value: 0.43), methyl castor oil fatty acid (IOB value: 0.43), ethylene glycol palmitate (IOB value: 0.44), polyethylene glycol dilaurate (IOB value: 0.45), and tripropylene glycol dipivalate (IOB value: 0.52), ethylhexyl methoxycinnamate (IOB value: 0.28), isononyl isononanoate (IOB value: 0.2), octyldodecanol (IOB value: 0.26), diisostearyl malate (IOB value: 0.28), di(phytosteryl / octyldodecyl) lauryl glutamate (IOB value: 0.30), tri(caprylic / capric)glycerin (IOB value: 0.33), 2-ethylhexyl hydroxystearate (IOB value: 0.31), propylene glycol dicaprylate (IOB value: 0.32), glyceryl tri-2-ethylhexanoate (IOB value: 0.35), octyldodecyl lactate (IOB value: 0.35), diisopropyl sebacate (IOB value: 0.40), and castor oil (IOB value: 0.43) may be one or more selected from the group consisting of:

[0055] (3-2) Volatile oils Hereinafter, more preferred forms of the volatile oil used in the W / O type Pickering emulsion of the present invention will be described.

[0056] The W / O type Pickering emulsion of the present invention contains a volatile oil in an amount of preferably 10% by mass or more, more preferably 20% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total amount of the oil.

[0057] Furthermore, the W / O type Pickering emulsion of the present invention contains a volatile oil in an amount of preferably 95% by mass or less, more preferably 92.5% by mass or less, more preferably 90% by mass or less, even more preferably 87.5% by mass or less, and particularly preferably 85% by mass or less, based on the total amount of the oil.

[0058] By setting the content of the volatile oil within the above range, it is possible to provide a W / O type Pickering emulsion that has the effect of inhibiting the coalescence of emulsified droplets over time.

[0059] More preferred embodiments of the types of oil contained in the W / O type Pickering emulsion of the present invention will be described in detail below.

[0060] Preferred examples of the volatile oil include volatile silicone oil, volatile hydrocarbon oil, volatile ester oil, volatile natural animal and vegetable oil, and volatile fluorine oil, and preferred examples include volatile silicone oil and volatile hydrocarbon oil.

[0061] Preferred examples of the volatile silicone oil include dimethylpolysiloxane, methyltrimethicone, tris(trimethylsilyl)methylsilane, tetrakis(trimethylsilyl)silane, hexacyclotrisiloxane, octamethyltetracyclosiloxane, cyclopentasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and tetradecamethylcycloheptasiloxane.

[0062] Preferred examples of the volatile hydrocarbon oil include decane, undecane, dodecane, tridecane, isooctane, isodecane, isododecane, isohexadecane, cyclodecane, and cyclododecane.

[0063] (4) Water phase components The water content in the aqueous phase of the W / O type Pickering emulsion of the present invention is preferably 5% by mass or more, more preferably 25% by mass or more, even more preferably 35% by mass or more, particularly preferably 40% by mass or more, and most preferably 45% by mass or more.

[0064] The water content in the aqueous phase is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0065] The water content is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, still more preferably 0.4 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 1 part by mass of the total amount of the oil agent described above. The content of water is preferably 2 parts by mass or less per 1 part by mass of the total amount of the oil agent described above.

[0066] The content of water is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, and even more preferably 0.5 parts by mass or more, per part by mass of the volatile oil.

[0067] The content of water is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, even more preferably 3 parts by mass or less, and particularly preferably 2.5 parts by mass or less, per part by mass of the volatile oil.

[0068] The content of the total amount of the aqueous phase relative to the total amount of the W / O type Pickering emulsion is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, and most preferably 30% by mass or more.

[0069] Furthermore, the content of the total amount of the aqueous phase relative to the total amount of the W / O type Pickering emulsion is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, particularly preferably 60% by mass or less, and most preferably 55% by mass or less.

[0070] The aqueous phase in the W / O type Pickering emulsion of the present invention can contain any component typically used in cosmetics without any particular limitation, but it preferably contains, for example, the following components:

[0071] Examples of polyols include polyethylene glycol, glycerin, 1,3-butylene glycol, erythritol, sorbitol, xylitol, maltitol, propylene glycol, dipropylene glycol, diglycerin, isoprene glycol, 1,2-pentanediol, 2,4-hexylene glycol, 1,2-hexanediol, and 1,2-octanediol. Of these, glycerin, 1,3-butylene glycol, and sorbitol are preferred. The content of these additives is preferably 0.5% by mass or more, more preferably 3% by mass or more, of the total W / O type Pickering emulsion. The content of the polyol is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0072] The W / O type Pickering emulsion of the present invention may also contain a thickener. Preferred examples of the thickener include xanthan gum, gellan gum, guar gum, quince seed, carrageenan, galactan, gum arabic, pectin, mannan, starch, curdlan, methylcellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methylhydroxypropyl cellulose, 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, keratosulfuric acid, locust bean gum, succinoglucan, caronic acid, chitin, chitosan, carboxymethyl chitin, agar, polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, sodium polyacrylate, polyethylene glycol, sodium acrylate-grafted starch, stearoxyhydroxypropylmethylcellulose, and bentonite.

[0073] The content of the thickener is preferably 0.05% by mass or more, and more preferably 0.1% by mass or more, of the total W / O type Pickering emulsion. The content of the thickener is preferably 5% by mass or less, and more preferably 1% by mass or less, of the entire W / O type Pickering emulsion.

[0074] (5) Other ingredients The W / O type Pickering emulsion of the present invention may contain optional ingredients that are normally used in cosmetics in addition to the above-mentioned ingredients, as long as the effects of the invention are not impaired.

[0075] <2> Method for producing W / O type Pickering emulsion The W / O type Pickering emulsion of the present invention can be produced by the following production method. First, the method includes a step of preparing an aqueous phase appropriately containing the above-mentioned optional components, and a step of preparing the above-mentioned oil phase.

[0076] Here, the present invention is characterized in that the aqueous phase contains magnesium sulfate and / or an organic acid salt. In a preferred embodiment of the present invention, the oil phase contains an oil agent and a hydrophobized powder, and the oil agent contains a volatile oil agent in an amount of 40 mass % or more relative to the total amount of the oil agent.

[0077] Next, the aqueous phase and the oil phase are mixed together, whereby the hydrophobized powder emulsifies the aqueous phase and the oil phase, producing the W / O type Pickering emulsion of the present invention.

[0078] When the W / O type Pickering emulsion of the present invention and a cosmetic preparation containing the same are stored in a container, the powder is present at the interface between the water phase and the oil phase, and the emulsion is maintained.

[0079] The above description can be applied to preferred embodiments of the method for producing a W / O type Pickering emulsion of the present invention. [Example]

[0080] <Test Example 1> In Test Example 1, the effects of magnesium sulfate and / or an organic acid salt on a W / O type Pickering emulsion were confirmed.

[0081] (1) Production of emulsion composition The aqueous phase and oil phase shown in Table 1 below were prepared, and then mixed and emulsified to obtain emulsion compositions.

[0082] Here, Examples 1 to 3, 6 and 7 are W / O type Pickering emulsions containing silica silylate (corresponding to the hydrophobic powder in the present invention) and magnesium sulfate. Moreover, Examples 4, 6, and 7 are W / O type Pickering emulsions containing silica silylate (corresponding to the hydrophobic powder in the present invention) and sodium citrate (corresponding to the organic acid salt in the present invention). In addition, Example 5 is a W / O type Pickering emulsion that contains hydrogen dimethicone-treated titanium oxide as another hydrophobic powder and also contains magnesium sulfate.

[0083] Here, as Comparative Example 1, a W / O type emulsion composition (an emulsion composition that is not a W / O type Pickering emulsion) was prepared, which was produced using a surfactant (a silicone-based surfactant) instead of a hydrophobic powder. Comparative Example 2 was a W / O type Pickering emulsion containing silica silylate (corresponding to the hydrophobic powder of the present invention) but not containing magnesium sulfate and / or an organic acid salt.

[0084] (2) Evaluation items and evaluation methods The produced emulsion compositions were subjected to the tests shown in Table 1. The results are shown in Table 1.

[0085] (2-1) Inhibition of emulsion droplet coalescence over time The produced emulsion composition was allowed to stand at room temperature for one week, and the degree of coalescence of the emulsion droplets was observed under an optical microscope and evaluated in three stages according to the following criteria. ○ No coalescence of emulsion droplets occurs. △: A small amount of coalescence of emulsion droplets occurs. × A large amount of emulsified droplets coalesce.

[0086] (2-2) Non-stickiness Five evaluators specializing in the research and development of cosmetics evaluated the stickiness of the manufactured emulsion compositions when they touched the skin during application, using the following five-point scale. The evaluation results in the table are the total scores of the five evaluators specializing in the research and development of cosmetics. 5. No sticky feeling on the skin during application. 4. There is almost no stickiness on the skin during application. 3: The skin feels a little sticky during application. 2: The skin feels sticky during application. 1: The skin feels quite sticky during application.

[0087] [Table 1]

[0088] (2-3) Free evaluation by evaluators The comparative examples were subjected to free evaluation by the evaluators. As a result of the free evaluation, Comparative Example 1 was evaluated as having coalescence of emulsified droplets and causing stickiness. Furthermore, Comparative Example 2 did not become water in oil and was evaluated as not worthy of evaluation.

[0089] (3) Results and Discussion The results of this test showed that a W / O type Pickering emulsion containing magnesium sulfate and / or an organic acid salt was excellent in terms of non-stickiness and suppressing the coalescence of emulsified droplets over time. [Industrial Applicability]

[0090] The present invention can be applied to W / O type Pickering emulsions.

Claims

1. A W / O type Pickering emulsion comprising an aqueous phase, an oil phase, and a hydrophobized powder, the W / O type Pickering emulsion contains magnesium sulfate and / or an organic acid salt, The particle size of the hydrophobized powder is an average primary particle size of 200 nm or less, the hydrophobic powder is silica silylate and / or hydrogen dimethicone-treated titanium oxide, the organic acid salt is any one selected from lactate, malate, citrate, and succinate; the content of the magnesium sulfate and / or organic acid salt is 0.1 mass% or more based on the total amount of the W / O type Pickering emulsion, the content ratio of the magnesium sulfate and / or organic acid salt to the hydrophobic powder is in the range of 1:0.2 to 1:100; W / O type Pickering emulsion.

2. A W / O type Pickering emulsion as described in claim 1, wherein the content ratio of the magnesium sulfate and / or organic acid salt to the hydrophobic powder is within the range of 1:2 to 1:

10.

3. 3. The W / O type Pickering emulsion according to claim 1, wherein the hydrophobic powder is silica silylate.

4. A W / O type Pickering emulsion described in any one of claims 1 to 3, wherein the organic acid salt is sodium citrate.

5. The W / O type Pickering emulsion according to any one of claims 1 to 4, characterized in that the oil phase contains a volatile oil in an amount of 40 mass% or more relative to the total amount of oils contained in the oil phase.

6. A cosmetic comprising the W / O type Pickering emulsion according to any one of claims 1 to 5.

7. The cosmetic according to claim 6, which is a foundation or a sunscreen.

8. A method for producing a W / O type Pickering emulsion containing an aqueous phase, an oil phase, and a hydrophobized powder, comprising: The method comprises the steps of preparing an aqueous phase and preparing an oil phase, the aqueous phase contains magnesium sulfate and / or an organic acid salt; The particle size of the hydrophobic powder is an average primary particle size of 200 nm or less, the hydrophobic powder is silica silylate and / or hydrogen dimethicone-treated titanium oxide, the organic acid salt is any one selected from lactate, malate, citrate, and succinate; the content of the magnesium sulfate and / or organic acid salt is 0.1 mass% or more based on the total amount of the W / O type Pickering emulsion, A method for producing a W / O type Pickering emulsion, characterized in that the content ratio of the magnesium sulfate and / or organic acid salt to the hydrophobic powder is within a range of 1:0.2 to 1:100.

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