JP2018104392A - Method for modifying powder particle surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method for modifying powder particle surface, a method for preparing a Pickering emulsion in various emulsified states, and a novel Pickering emulsion.SOLUTION: The method for modifying powder particle surface involves immersing the powder particles in an oil solution having an oxygen atom in the molecular structure. An emulsion state adjustment method comprises a step of modifying the powder particle surface using the method for modifying powder particle surface, and a step of adjusting the ratio of the oil and water phases.EFFECT: The powder particle surface can be simply modified, and a Pickering emulsion in various emulsified states can be prepared. In the method for modifying powder particle surface it is preferable for the surface of the powder particle to have a hydroxyl group and/or at least a silanol group, and for the powder particle to be a metal particle comprising titanium oxide.SELECTED DRAWING: None

Description

  The present invention relates to a method for modifying the surface of powder particles, a pickering emulsion using particles whose surface has been modified, and a method for producing a pickering emulsion.

  An emulsion refers to two or more liquids that do not mix with each other and one liquid is dispersed in the other liquid. As an emulsion, an oil-in-water type (O / W) in which oil droplets are dispersed in water and a water-in-oil type (W / O type) in which water droplets are dispersed in oil are known. It is applied to the agent.

  In order to form such an emulsion, an amphiphilic substance called an emulsifier is usually used. This emulsifier can reduce the interfacial tension by adsorbing at the interface of the two phases and stabilize the emulsion by increasing steric hindrance or electrostatic repulsion.

  However, most of those used as emulsifiers are surfactants, and surfactants are irritating to the skin. Therefore, it is desirable to use emulsion-free external preparations that do not contain surfactants. .

  As an emulsion not containing an emulsifier, a fine particle stabilized emulsion (Pickering emulsion) is known. Pickering emulsion refers to an emulsion stabilized by finely dispersed solid particles adsorbed on the interface between two phases.

  So far, it has been proposed to use solid particles whose surfaces have been hydrophobized for the preparation of a pickering emulsion (Patent Documents 1 and 2).

Special table 2007-530721 gazette Special table 2010-527332

  However, in the method of hydrophobizing the surface of the solid particles, the surface treatment agent must be changed in accordance with the shape and emulsion particle size of the target emulsion, and the desired emulsion may not be produced. It takes a lot of work.

  Accordingly, a first problem to be solved by the present invention is to provide a method for easily modifying the surface of particles. Further, the present invention makes it possible to prepare pickering emulsions in various emulsified states, and it is a second object to provide a novel pickering emulsion, preferably.

As a result of intensive studies, the present inventors have found that the surface of the powder particles can be easily modified by immersing the particles in a specific oil agent and changing the immersion time, thereby completing the present invention.
That is, the present invention for solving the first problem is a method for modifying the surface of powder particles, wherein the powder particles are immersed in an oil agent having an oxygen atom in the molecular structure.
In the prior art, in order to obtain powder particles having the desired surface characteristics in order to obtain an emulsion having an arbitrary emulsified state, it is necessary to first select a surface treatment agent and make it difficult to react with the particles. Met. However, according to the method for modifying the surface of the powder particles of the present invention, the surface of the powder particles can be easily modified without taking such a complicated process.

The modifying method of the present invention is preferably applied to powder particles having a hydroxyl group on the surface of the powder particles.
Since powder particles having hydroxyl groups on the surface of the powder particles are likely to interact with an oil agent having an oxygen atom in the molecular structure, the surface of the powder particles is particularly easily modified.

The modifying method of the present invention is preferably applied to powder particles having silanol groups on the surface of the powder particles.
Since powder particles having silanol groups on the surface of the powder particles are likely to interact with an oil agent having an oxygen atom in the molecular structure, the surface of the powder particles is particularly easily modified.

The modifying method of the present invention is preferably applied to powder particles containing a metal oxide.
By modifying the surface of the powder particles containing a metal oxide according to the present invention, it is possible to obtain a pickering emulsion stabilized with a metal oxide, which is usually difficult to prepare.

The modification method of the present invention is preferably applied to powder particles containing titanium oxide.
By modifying the surface of the powder particles containing titanium oxide according to the present invention, it is possible to obtain a stable pickering emulsion having ultraviolet protection ability.

In a preferred embodiment of the present invention, the oil agent is silicone oil.
By immersing the powder particles in silicone oil, the surface of the particles can be more easily modified.

In a preferred embodiment of the present invention, the oil agent is a cyclic silicone oil.
Cyclic silicone oil is generally used as an oil for skin external preparations such as sunscreen agents. Therefore, powder particles that can be applied to an external preparation for skin can be provided by immersing the powder particles in a cyclic silicone oil.

In a preferred embodiment of the present invention, the step of immersing the powder particles in the oil is performed at room temperature or higher.
By performing the dipping step at room temperature or higher, the dipping time for modifying the surface of the powder particles can be shortened.

Further, the present invention for solving the second problem is a method for adjusting an emulsified state of a pickering emulsion, wherein the powder particle surface is modified using the powder particle surface modification method; And a step of adjusting the ratio between the oil phase and the water phase.
According to the method for adjusting the emulsified state of the present invention, the emulsified state of the emulsion can be easily adjusted.

Further, the present invention for solving the second problem performs the step of modifying the surface of the particle using the above-described method for modifying the surface of the powder particle, and emulsification using the particle whose surface is modified. A process for producing a pickering emulsion.
According to the method for producing a pickering emulsion of the present invention, various forms of emulsion can be easily produced.

  According to the powder particle surface modification method of the present invention, the surface of the powder particles can be modified easily. Moreover, according to the method for producing a pickering emulsion of the present invention, pickering emulsions in various emulsified states can be produced.

FIG. 1 is a flowchart of a method for adjusting an emulsified state. FIG. 2 is a drawing-substituting photograph showing emulsified particles of a pickering emulsion.

<1> Powder Particles The method for modifying the surface of powder particles of the present invention can be applied to any powder particles of organic powder and inorganic powder.
Examples of the inorganic powder include metals, metal salts, metal oxides, metal hydroxides, and minerals.
Examples of the organic powder include organic polymer powder.

  The method for modifying the surface of the powder particles of the present invention can also be applied to composite particles obtained by combining two or more of these powders.

Further, the present invention can also be applied to powder particles in which the surface of the powder particles is entirely or partially covered with a surface treatment agent.
Here, “the whole or part of the powder particle surface is coated” means not only the state in which the surface treatment agent is physically adhered to the surface of the powder particle but also the surface of the powder particle. It also includes a state in which the compound is covalently bonded to the functional group exposed to the surface.

  As the surface treatment agent, a plating treatment agent, a hydrophobization treatment agent, a hydrophilic treatment agent, or the like can be used. Titanium oxide, iron oxide, zinc oxide, aluminum oxide, lead oxide, tin oxide, organosilicon compound, silicone, Examples include hydrocarbon oil, fatty acid, fatty acid amide, fatty acid ester, higher alcohol, polyoxyalkylene compound, polyethylene glycol, polyvinyl alcohol, polyacrylic acid, polyphosphoric acid, metaphosphoric acid, hyaluronic acid, alginic acid, and salts thereof.

The method for modifying the powder particle surface of the present invention is preferably applied to powder particles having a hydroxyl group on the powder particle surface.
Examples of the “powder particles having a hydroxyl group on the powder particle surface” include, for example, powders having surface hydroxyl groups such as metal oxides and silica, and powders composed of molecules having hydroxyl groups on the structural formula such as water-soluble polymers. The body is mentioned.

  Further, powder coated with a surface treatment agent having a hydroxyl group is also included in the “powder particles having a hydroxyl group on the powder particle surface”.

  Further, composite particles of the above-mentioned “powder particles having a hydroxyl group on the powder particle surface” and other powder particles are also included in the “powder particles having a hydroxyl group on the powder particle surface”.

In addition, the method for modifying the surface of the powder particles of the present invention is preferably applied to powder particles having silanol groups on the surface of the powder particles.
Here, the silanol group includes any silanol group such as an isolated silanol group, a vicinal silanol group, and a geminal silanol group.

Examples of powder particles having hydroxyl groups or silanol groups on the surface of the powder particles include silica particles alone and composite particles in which the powder particle surface is entirely or partially covered with silica particles.
Such composite particles can be easily modified on the particle surface by the modifying method of the present invention. Silica particles are usually used as an emulsified powder of a pickering emulsion, and are preferable because they can form a pickering emulsion having high stability. Furthermore, since the silica particles are non-toxic to the human body, the pickering emulsion produced using the silica particles can be applied to cosmetics, foods, medicines and the like.

As the silica particles, 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 (Toso Silica). Co., Ltd.), and commercial products such as HI-SIL series (PPG) can be used.

Further, the method for modifying the surface of the powder particles of the present invention is preferably applied to composite particles containing a metal oxide.
Preferred examples of the metal oxide include titanium oxide, iron oxide, zinc oxide, aluminum oxide, lead oxide and tin oxide, and titanium oxide is more preferred.
In general, as powder particles for producing a pickering emulsion, those containing a metal oxide are rarely used, but by applying the method for modifying the powder particle surface of the present invention, the metal oxide is used. Can be easily applied to the pickling emulsion.

The present invention is particularly preferably applied to composite particles containing a metal oxide as a main component.
Furthermore, the present invention is preferably applied to composite particles containing a metal oxide as a main component and containing silica particles as a subordinate component.
In this case, the content of the silica particles in the entire composite particle is not particularly limited, but from the viewpoint of reducing the time required for modifying the surface of the powder particles, the lower limit is preferably 7% by mass or more, and more preferably. Is preferably 12% by mass or more, more preferably 15% by mass or more, and still more preferably 18% by mass or more.

  Further, the content of silica particles in the whole composite particles containing a metal oxide as a main component is 45% by mass or less, more preferably 40% from the viewpoint of shortening the time required for modifying the surface of the powder particles. It is preferable to set it as mass% or less, More preferably, it is 35 mass% or less, More preferably, it is 30 mass% or less.

Further, the present invention is preferably applied to composite particles containing aluminum oxide particles (Al ₂ O ₃ ) as subordinate components and containing other metal oxides as main components.
In this case, the content of the aluminum oxide particles in the entire composite particles is not particularly limited, but from the viewpoint of reducing the time required for modifying the surface of the powder particles, the lower limit is preferably 0.1% by mass or more. More preferably, it is 1% by mass or more, more preferably 2% by mass or more, and further preferably 3% by mass or more.
On the other hand, the upper limit of the content of aluminum oxide particles in the entire composite particle is not particularly limited, and can be preferably 20% by mass or less, more preferably 10% by mass or less.

  Here, “including as a main component” means “including with a content of 50% by mass or more of the whole”. On the other hand, “include as a subordinate component” means “include with less than 50% by mass of the total”.

  The composite particles can be produced by mixing the constituent powders using a mixer such as an automatic mortar, ball mill, Henschel mixer, Nauter mixer, Redige mixer, V-type mixer, hammer mill, pin mill or the like.

<2> Oil agent having an oxygen atom in the molecular structure
The oil agent having an oxygen atom in the molecular structure used in the method for modifying the surface of the powder particles of the present invention includes functional groups such as hydroxy group, aldehyde group, carbonyl group, carboxy group, nitro group and sulfo group in the molecular structure. Or an oil agent having a bond such as a siloxane bond, an ether bond or an ester bond.

  Examples of the oil agent having an oxygen atom in the molecular structure include liquid oil and fat, solid oil and fat, wax, higher fatty acid, higher alcohol, ester oil, and silicone oil.

  Examples of liquid 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 castor oil, castor oil, linseed oil , Safflower oil, cottonseed oil, eno oil, meadow foam oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, cinnagari oil, Japanese kiri oil, jojoba oil, germ oil, triglycerin, glycerin trioctanoate, Examples thereof include glycerin triisopalmitate.

  Solid fats and oils include cocoa butter, coconut oil, horse fat, hydrogenated coconut oil, palm oil, beef tallow, sheep fat, hardened beef tallow, palm kernel oil, pork fat, beef bone fat, owl kernel oil, hydrogenated oil, cow leg fat , Mole, 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, lauryl hexyl, reduced lanolin, jojojo Examples thereof include wax, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, and POE hydrogenated lanolin alcohol ether.

  Examples of higher fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, behen (behenine) acid, 12-hydroxystearic acid, undecylenic acid, and toric acid.

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

  Ester oils include isopropyl myristate, cetyl octanoate, octyldodecyl 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-hydroxystearylate, Ethylene glycol di-2-ethylhexylate, Dipentaerythritol fatty acid ester, N-alkylglycol monoisostearate, Dicaprin Acid neopentyl glycol, diisostearyl malate, glycerin di-2-heptylundecanoate, tri-2-ethylhexyl Trimethylolpropane triacid, trimethylolpropane triisostearate, pentane erythritol tetra-2-ethylhexylate, glycerin tri-2-ethylhexylate, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate Glyceryl trimyristate, glyceride tri-2-heptylundecanoate, castor oil fatty acid methyl ester, 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-ethylhexa 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, triethyl citrate and the like.

  Silicone oils include chain silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, diphenylsiloxyphenyltrimethicone, pentasiloxane, decamethylpolysiloxane, dodecamethylpolysiloxane, tetramethyltetrahydro Examples thereof include cyclic silicone oils such as genpolysiloxane.

In the method for modifying the powder particle surface of the present invention, as the oil agent having an oxygen atom in the molecular structure, it is more preferable to use silicone oil, and it is more preferable to use cyclic silicone oil.
By using silicone oil, the surface of the powder particles can be more easily modified.
Cyclic silicone oil is generally used as an oil agent for sunscreen agents. In the method for modifying the surface of the powder particles of the present invention, the use of a cyclic silicone oil as the oil agent facilitates application to a skin external preparation such as cosmetics.

<3> Powder Particle Surface Modification Method According to the powder particle surface modification method of the present invention, the powder particle surface is immersed in an oil agent having an oxygen atom in the molecular structure. More specifically, the degree of hydrophobicity of the surface of the powder particles can be improved. Here, “immersing powder particles in an oil agent having an oxygen atom in the molecular structure” means bringing the entire surface of the powder particles into contact with the oil agent.

  By using the powder particle surface modification method, particles having wettability can be modified to be lipophilic particles, and particles having wettability can be made more lipophilic. It can be modified into particles.

When preparing a pickering emulsion using powder particles, the emulsified state of the pickering emulsion (water-in-oil / oil-in-water, emulsified particle size, emulsion stability, etc.) depends on the wetness of the surface of the powder particles. It depends on sex.
In other words, if the modification method of the present invention is applied to a certain powder particle and a pickering emulsion is prepared using the powder particle after application, the pickering emulsion prepared using the same powder particle before application and It shows a different emulsified state.

The temperature of the oil agent when the powder particles are immersed in the oil agent having an oxygen atom in the molecular structure is preferably room temperature or higher, more preferably 50 ° C. or higher, further preferably 60 ° C. or higher, particularly preferably 70 ° C. or higher. is there.
By setting it as the said temperature range, the surface of particle | grains can be modify | reformed in short immersion time.

  The time for immersing the powder particles in the oil having an oxygen atom in the molecular structure is not particularly limited. Depending on the type and composition of the powder particles, if you want to obtain an effect that the oil phase and the water phase are reversed in the pickering emulsion prepared using the powder particles before and after applying the modification method of the present invention The time for immersing the powder particles in the oil may be 6 hours or more at room temperature or 30 minutes or more at 80 ° C.

  The degree of modification of the surface of the powder particles can be confirmed by measuring the contact angle according to a conventional method. Moreover, it can also confirm by emulsifying using the particle | grains and manufacturing a Pickering emulsion.

  The properties of the pickering emulsion such as the emulsion stability and the emulsion particle size depend on the surface properties of the powder particles. Therefore, a pickering emulsion having an arbitrary property can be obtained by adjusting the surface characteristics of the powder particles by the modification method of the present invention.

  After the powder particles are immersed in the oil agent for a certain period of time, they are separated from the oil agent, whereby powder particles having a modified surface can be obtained.

<4> Method for adjusting emulsified state The present invention comprises an emulsified state comprising the step of modifying the powder particle surface using the above-described method for modifying the surface of the powder particle, and the step of adjusting the ratio of oil and water. It also relates to the adjustment method.
According to the method for adjusting the emulsified state of the present invention, the pickering emulsion can be adjusted to various emulsified states by adjusting the immersion time of the particles and the ratio of the water phase and the oil phase.

Conventionally, in order to obtain a pickering emulsion in an arbitrary emulsified state, it has been common to optimize the surface properties of the powder particles by coating the surface of the powder particles with an appropriate surface treatment agent.
According to the method for adjusting an emulsified state of the present invention, it is possible to adjust the emulsified state of the pickering emulsion without requiring the troublesome work of selecting and coating an appropriate surface treatment agent.

  FIG. 1 is a flowchart showing a method for adjusting an emulsified state. With reference to this, the adjustment method of the emulsification state of this invention is demonstrated in detail.

  First, in step S1, a pickering emulsion is manufactured using arbitrary powder particles, and the emulsified state is evaluated. Evaluation items include the type of emulsification such as W / O type or O / W type, the emulsified particle diameter, and the stability of the emulsified state. It can be estimated from the evaluation in step S1 how to adjust any powder particles to obtain a pickering emulsion in any emulsified state.

  Specifically, for water-in-oil pickering emulsions, the longer the immersion time in the oil agent having oxygen atoms in the molecular structure of the powder particles, the more emulsified particles of the pickering emulsion prepared using the same The diameter can be increased.

  For oil-in-water pickering emulsions, the longer the immersion time of the powder particles in the oil agent, the smaller the emulsion particle diameter of the pickering emulsion can be prepared by using it. If the time is increased, a water-in-oil pickering emulsion can be obtained.

In step S2, in order to adjust the emulsification state of the pickering emulsion, the step of modifying the powder particle surface (step S3), the step of adjusting the ratio of the water phase and the oil phase (step S4), and these two Choose whether to perform the process simultaneously.
For step S3, the powder particle surface modification method described in <3> is used.
About step S4, the ratio of a water phase and an oil phase is adjusted with a conventional method.

  A pickering emulsion is prepared with the powder particles whose surface has been modified in step S3 and the ratio of the water phase and the oil phase adjusted in step S4. The pickering emulsion is evaluated in step S5. Evaluation items are the same as in S1.

  And in step S6, adjustment will be complete | finished if the prepared pickering emulsion will be in arbitrary emulsification states. When the prepared pickering emulsion is not in any emulsified state, the process returns to step S2.

As the powder particles used in the adjustment method of the present invention, those described in <1> can be used.
Although not shown, a step of selecting powder particles may be provided after step S2 in parallel with steps S3 and S4. More specifically, when the composite particles are used for the preparation of the pickering emulsion, a step of adjusting the ratio of the powder particles constituting the composite particles may be provided.

  In the method for adjusting the emulsified state of the present invention, either water or an aqueous solution can be used as the aqueous phase. In addition to the oil agent described in <2>, a hydrocarbon oil or the like can be used as the oil phase.

<5> Method for Producing Pickering Emulsion According to the method for producing a pickering emulsion of the present invention, the surface of the particle is modified using the method for modifying a powder particle surface described in <3>. By emulsifying using modified particles, pickering emulsions with various forms and particle sizes can be obtained.

  As the oil phase of the pickering emulsion, a hydrocarbon oil or the like can be used in addition to the oil agent described in <2>.

  The method for producing a pickering emulsion according to the present invention produces a pickering emulsion by adding an oil, water or an aqueous solution having an oxygen atom to the molecular structure in which the particles are immersed after the powder particle surface is modified. It can be set as an embodiment.

  Further, after modifying the surface of the powder particles, the powder particles whose surface is modified are separated from the oil agent having an oxygen atom in the molecular structure, and separately prepared oil phase and water are used using the powder particles. It can also be set as the embodiment which manufactures a pickering emulsion by emulsifying a phase. A conventional method can be used as a method for separating the oil agent and the powder particles, and examples thereof include centrifugation.

  A conventional method can be used for the emulsification step in the method for producing the pickering emulsion of the present invention.

  Further, according to the method for producing a pickering emulsion of the present invention, a pickering emulsion containing particles in a form that could not be produced by the prior art can be produced.

<6> Pickering emulsion The present invention also relates to a pickering emulsion manufactured by the above-described manufacturing method. That is, the present invention is a pickering emulsion comprising powder particles immersed in an oil agent having an oxygen atom in the molecular structure.

Regarding the oil agent, the matters described in <2> can be applied as they are.
In the present invention, an embodiment including powder particles immersed in a cyclic silicone oil is particularly preferable.

  The invention also relates to a pickering emulsion, characterized in that it comprises powder particles coated with a cyclic silicone oil.

  Examples of the cyclic silicone oil used in the present invention include pentasiloxane, decamethylpolysiloxane, dodecamethylpolysiloxane, and tetramethyltetrahydrogenpolysiloxane.

  As the powder particles, those described in <1> can be applied as they are.

In the pickering emulsion of this invention, the arbitrary component normally used by cosmetics other than the said component can be contained in the range which does not impair the effect of invention. Such optional components include fatty acid soap (sodium laurate, sodium palmitate, etc.), anionic surfactants such as potassium lauryl sulfate, triethanolamine ether of alkyl sulfate, stearyltrimethylammonium chloride, benzalkonium chloride, laurylamine oxide. Cationic surfactants such as imidazoline-based amphoteric surfactants (2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt, etc.), betaine surfactants (alkyl betaines, amide betaines, Amphoteric surfactants such as sulfobetaine), acylmethyl taurine, sorbitan fatty acid esters (sorbitan monostearate, sorbitan sesquioleate, etc.), glycerin fatty acids (glyceryl monostearate, etc.) , Propylene glycol fatty acid esters (such as propylene glycol monostearate), hardened castor oil derivatives, glycerin alkyl ether, POE sorbitan fatty acid esters (such as POE sorbitan monooleate, polyoxyethylene sorbitan monostearate), POE sorbite fatty acid ester (POE-sorbitol monolaurate, etc.), POE glycerin fatty acid esters (POE-glycerol monoisostearate, etc.), POE fatty acid esters (polyethylene glycol monooleate, POE distearate, etc.), POE alkyl ethers (POE2-octyl) Dodecyl ether, etc.), POE alkyl phenyl ethers (POE nonyl phenyl ether, etc.), pluronic types, POE / POP alkyl ethers, etc. Nonionic surfactants such as POE / POP2-decyltetradecyl ether), tetronics, POE castor oil / hardened castor oil derivatives (POE castor oil, POE hardened castor oil, etc.), sucrose fatty acid esters, alkyl glucosides, etc. , Moisturizing ingredients such as sodium pyrrolidone carboxylate, lactic acid, sodium lactate, surface treated, mica, talc, kaolin, synthetic mica, calcium carbonate, magnesium carbonate, silicic anhydride (silica), aluminum oxide, sulfuric acid Powders such as barium, surface treated, cobalt oxide, ultramarine, bitumen, zinc oxide inorganic pigments, surface treated, composite pigments such as iron oxide titanium dioxide sintered body, surface Pearling agents such as titanium mica, fish phosphorus foil, bismuth oxychloride, which may be treated, raked Red 202, Red 228, Red 226, Yellow 4, Blue 404, Yellow 5, Red 505, Red 230, Red 223, Orange 201, Red 213, Yellow 204 No., yellow No. 203, blue No. 1, green No. 201, purple No. 201, red No. 204, etc., organic powders such as polyethylene powder, polymethyl methacrylate, nylon powder, organopolysiloxane elastomer, ethanol , Lower alcohols such as isopropanol, vitamin A or derivatives thereof, vitamin B ₆ hydrochloride, vitamin B ₆ tripalmitate, vitamin B ₆ dioctanoate, vitamin B ₂ or derivatives thereof, vitamin B ₁₂ , vitamin B ₁₅ or derivatives thereof, etc. Vitamin B, α-tocopherol, β-tocopherol, γ-tocopherol, bi Vitamin E such as Tamine E acetate, Vitamin D, Vitamin H, Pantothenic acid, Panthetin, Pyroloquinoline quinone and other vitamins, paraaminobenzoic acid, paraaminobenzoic acid monoglycerin ester, N, N-dipropoxyparaaminobenzoic acid ethyl Esters, N, N-diethoxyparaaminobenzoic acid ethyl ester, N, N-dimethylparaaminobenzoic acid ethyl ester, N, N-dimethylparaaminobenzoic acid butyl ester, N, N-dimethylparaaminobenzoic acid ethyl ester, diethylaminohydroxybenzoyl Benzoic acid derivatives such as hexyl benzoate; Anthranilic acid derivatives such as homomenthyl-N-acetylanthranilate; Salicylic acid and its sodium salt, amyl salicylate, menthyl salicylate, homomenthyl Salicylic acid derivatives such as lysylate, octyl salicylate, phenyl salicylate, benzyl salicylate, p-isopropanolphenyl salicylate; octyl cinnamate, ethyl-4-isopropyl cinnamate, methyl-2,5-diisopropyl cinnamate, ethyl-2,4-diisopropyl Cinnamate, methyl-2,4-diisopropylcinnamate, propyl-p-methoxycinnamate, isopropyl-p-methoxycinnamate, isoamyl-p-methoxycinnamate, 2-ethylhexyl p-methoxycinnamate (methoxycinnamic acid Ethyl hexyl, octyl paramethoxycinnamate), 2-ethoxyethyl-p-methoxycinnamate (sinoxate), cyclohexyl-p-methoxycinnamate, ethyl α-cyano-β-phenylcinnamate, 2-ethylhexyl 2-cyano-3,3-diphenyl acrylate (octocrylene), glyceryl mono-2-ethylhexanoyl-diparamethoxycinnamate, ferulic acid and its derivatives, etc. Cinnamic acid derivatives; 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetra Hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone (oxybenzone-3), 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4-phenylbenzophenone 2-ethylhexyl-4′-pheny -Benzophenone derivatives such as benzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, 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) 2- (2′-hydroxy-5′-methylphenylbenzotriazole; dibenzalazine; dianisoylmethane; 5- (3,3-dimethyl-2-norbornylidene) -3-pentan-2-one; 4-t -Dibenzoylmethane derivatives such as butylmethoxydibenzoylmethane; Lutriazone; urocanic acid derivatives such as urocanic acid and ethyl urocanate; 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 1- (3,4-dimethoxyphenyl) -4,4-dimethyl-1, Hydantoin derivatives such as 3-pentanedione, dimethoxybenzylidenedioxoimidazolidinepropionate 2-ethylhexyl; phenylbenzimidazolazosulfonic acid, terephthalylidene dicamphulsulfonic acid, drometrizol trisiloxane, methyl anthranilate, bisethylhexyloxy Illustrative are UV absorbers such as phenol methoxyphenyl triazine, rutin and its derivatives, oryzanol and its derivatives.

The pickering emulsion of the present invention may contain a surfactant, but its content is preferably reduced as much as possible. The content of the surfactant is preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.1% by mass or less, and particularly preferably 0% by mass.
By setting it as such a form, the skin irritation by surfactant can be suppressed, the stickiness at the time of use can be reduced, and makeup retention and stability can be improved.

The pickering emulsion of the present invention is suitable for a skin external preparation. Of these, a sunscreen skin external preparation is preferred.
In particular, it is preferably used for cosmetics, and preferably used as a sunscreen, makeup base and the like.

<Sample and Test Method> Modification of Powder Particle Surface and Production of Pickering Emulsion Preparation of powder particles and modification of the surface and production of Pickering emulsion used in Test Examples 1 to 3 described below are as follows. Of (1) and (2).
(1) Preparation of powder particles Powder particles were mixed with the composition shown in Table 1 to prepare nine particles 1 to 9.

(2) Modification of surface of powder particles The powder particles were immersed in decamethylcyclopentasiloxane contained in a glass bottle at a constant temperature for a fixed time. The weight fraction of the powder particles in decamethylcyclopentasiloxane was adjusted to be 0.0125.

(3) Production of Pickering Emulsion After the powder particles are immersed in an oil agent having an oxygen atom in the molecular structure for a certain period of time, an appropriate amount of water is added to the oil agent in which the powder particles are immersed. Using an ultrasonic device (Vibracell VCX130, tip diameter 3 mm, manufactured by Sonics & Material), emulsification was performed for 5 minutes under the condition of 20 kHz.
In order to evaluate the form of the formed emulsion, eosin blue was added to the aqueous phase and colored.

<Test Example 1> Form of formed emulsion Particles 3 and 9 were immersed in cyclopentasiloxane at 25 ° C for 0 minutes to 30 days to produce a Pickering emulsion. Water was added such that the weight fraction of water (φ _w ) was 0.10 to 0.80 with respect to the total weight of water and oil. The produced emulsion was observed and evaluated by observation with an optical microscope. The results for Particle 3 are shown in Table 2 (Example 1), and the results for Particle 9 are shown in Table 3 (Example 2).

  In Example 1, an o / w type pickering emulsion was formed under the conditions that the immersion time in the oil was 0 to 6 hours and the weight fraction of water was 0.1 to 0.8. Further, when the immersion time in the oil exceeds 6 hours, the emulsification state of the emulsion formed by the weight fraction of water changes, and the w / o type emulsion and the o / w / o or w / o / w type A double emulsion was formed.

On the other hand, Example 2 formed an o / w / o type emulsion when φ _w = 0.35 to 0.4, but it was emulsified when the immersion time exceeded 3 to 6 hours. No aqueous phase portion was observed.
From these results, it was found that by immersing the powder particles in an oil agent having an oxygen atom in the molecular structure, the degree of hydrophobicity of the particles is improved and the surface of the powder particles can be modified. Moreover, it turned out that the emulsification state of a pickering emulsion can be adjusted by adjusting the immersion time and the weight fraction of water and oil.

<Test Example 2> control particles 3 of emulsion particle size (Example 3) and particles 9 Pickering emulsion prepared with (Example 4) (Ts: 12 hours to 120 days, phi _w: 0.2) of The emulsified particle diameter was measured using an optical microscope. The results are shown in FIG.

From the results of Example 3, it was found that the emulsified particle size when the immersion time was 12 hours was about 6 μm, but the emulsified particle size when the immersion time was 120 days was 30 μm.
Moreover, from the result of Example 4, the small emulsification particle | grains seen by the emulsion of the immersion time 0 day (emulsion when emulsified without being immersed) were not seen by the emulsion of the immersion time 120 days.

  From these results, it was found that the water-in-oil pickering emulsion has a larger emulsified particle size as the immersion time in the oil agent having oxygen atoms in the molecular structure of the powder particles used for the preparation becomes longer.

  Moreover, when the photograph 12 hours after Example 3 is seen, it turns out that most of the emulsified particles are small and irregular. This is considered to be caused by the fact that it is immediately after the change from the o / w type to the w / o type pickering emulsion. From this result, the oil-in-water pickering emulsion has a smaller emulsified particle size as the immersion time in the oil agent having oxygen atoms in the molecular structure of the particles used for the preparation becomes longer. It turns out that it changes to a water type.

<Test Example 3>
Particles 1 to 8 were immersed in decamethylcyclopentasiloxane at 80 ° C. for a fixed time. Thereafter, water was added so that _φw was 0.2 to produce emulsions, and the morphology of each emulsion was observed and evaluated with an optical microscope. The results are shown in Table 4 (Examples 5 to 12).

  From the results of Table 4, no matter which particle is used, an o / w type emulsion is formed when the immersion time is short, but an o / w / o type or w / o type emulsion is formed when the immersion time is long. I found out that Moreover, it turned out that the immersion time changes with compositions of a powder particle.

Furthermore, from the results of Example 1 and Example 7 in Table 2 and Table 4, when immersion is performed at 25 ° C., a w / o type emulsion is formed by immersion for 6 hours or more, but immersion is performed at 80 ° C. When it did, it turned out that a w / o type emulsion is formed by being immersed for 1 hour or more.
From this result, it was found that the immersion time required for the modification of the powder particle surface can be shortened by increasing the temperature at which the particles are immersed in an oil agent having an oxygen atom in the molecular structure.

In addition, the pickering emulsion prepared above did not change its emulsified state over time after preparation.
As a result, when the powder particles are adsorbed at the interface between the water phase and the oil phase in the pickering emulsion, the surface characteristics are improved by having a part of the surface in contact with the oil phase. It shows that it is not.

The present invention can be applied to an emulsifier-type external skin preparation.

Claims (10)

  A method for modifying powder particle surfaces, comprising immersing powder particles in an oil agent having an oxygen atom in the molecular structure.   2. The method for modifying a powder particle surface according to claim 1, wherein the powder particle is a powder particle having a hydroxyl group on the powder particle surface.   The method for modifying a powder particle surface according to claim 1 or 2, wherein the powder particle is a powder particle having at least a silanol group on the surface.   The method for modifying a powder particle surface according to any one of claims 1 to 3, wherein the powder particles are powder particles containing a metal oxide.   The method for modifying a surface of a powder particle according to any one of claims 1 to 4, wherein the powder particle is a powder particle containing titanium oxide.   The method for modifying a powder particle surface according to any one of claims 1 to 5, wherein the oil agent is silicone oil.   The method for modifying a powder particle surface according to any one of claims 1 to 6, wherein the oil agent is a cyclic silicone oil.   The method for modifying a powder particle surface according to any one of claims 1 to 7, wherein the step of immersing the powder particles in the oil agent is performed at room temperature or higher.   A method for adjusting an emulsified state of a pickering emulsion, the step of modifying the powder particle surface using the method for modifying a powder particle surface according to any one of claims 1 to 8, and an oil A method for adjusting an emulsified state, comprising a step of adjusting a ratio of a phase and an aqueous phase. A step of modifying the surface of the particle using the method for modifying a surface of a powder particle according to any one of claims 1 to 8, and a step of emulsifying using the particle whose surface has been modified. A method for producing a pickering emulsion.