Method for producing dispersion

Abstract

To provide a method for producing a dispersion containing a sphingoid base having excellent storage stability.SOLUTION: There is provided a method for producing an oil in water type dispersion containing a sphingoid base, which comprises the following step 1. Step 1: a merging step of causing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30°C or more and a liquid water phase containing water and an acid to flow and merge, respectively; and a step of obtaining an oil in water type dispersion by a pore distribution step of distributing a fluid formed by merging the oil phase and the water phase in the merging step into pores.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing a dispersion.

Background Art

[0002] It is known to use a dispersion containing a sphingoid base in cosmetics and the like. For example, Patent Document 1 discloses, as a method for producing such a dispersion, mixing an ester oil that is liquid at 25°C, sphingosines, an acidic compound selected from inorganic acids and organic acids having 5 or less carbon atoms, and cholesterol or phytosterol using a homomixer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a method for producing a dispersion containing a sphingoid base, which has excellent storage stability.

Means for Solving the Problems

[0005] The present invention is a method for producing an oil-in-water type dispersion containing a sphingoid base, including the following step 1. Step 1: A step of obtaining an oil-in-water type dispersion by flowing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30°C or higher and a liquid water phase containing water and an acid, and then merging them, and a step of passing the fluid obtained by merging the oil phase and the water phase in the merging step through pores.

[0006] The present invention also relates to a method for producing an oil-in-water dispersion containing one or more of a sphingoid base, a polyvalent carboxylic acid compound, a polyvalent carboxylic acid compound and its salt, and an aromatic carboxylic acid compound and its salt, the method including the following steps 1 and 2. Step 1: A step of obtaining an oil-in-water dispersion by flowing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30°C or higher and a liquid aqueous phase containing water and an acid, respectively, and then merging them, and a step of flowing the fluid obtained by merging the oil phase and the aqueous phase in the merging step through pores. Step 2: A step of mixing the dispersion obtained in Step 1 with one or more of a polyvalent carboxylic acid compound, a polyvalent carboxylic acid compound and its salt, and an aromatic carboxylic acid compound and its salt.

Advantages of the Invention

[0007] According to the present invention, by flowing the fluid obtained by merging a liquid oil phase containing a sphingoid base and a solid fat and a liquid aqueous phase containing water and an acid through pores, an oil-in-water dispersion excellent in storage stability can be obtained, and a dispersion excellent in storage stability can also be obtained when mixed with one or more of a polyvalent carboxylic acid compound and its salt and an aromatic carboxylic acid compound and its salt.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail.

[0010] The method for producing an emulsion according to the embodiment includes a step of flowing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30°C or higher and a liquid aqueous phase containing water and an acid, respectively, merging them, and passing the merged fluid through pores to obtain an oil-in-water emulsion.

[0011] According to the method for producing an emulsion according to this embodiment, by passing the fluid obtained by merging the liquid oil phase containing a sphingoid base and a solid fat and the liquid aqueous phase containing water and an acid through pores, an oil-in-water emulsion excellent in storage stability can be obtained. This is considered to be because when the fluid in a low interfacial tension state obtained by merging the oil phase and the aqueous phase is passed through pores to apply shear, and the oil phase becomes fine particles and is dispersed in the aqueous phase, the sphingoid base is incorporated into the fine particles of the oil phase, and the amount of the sphingoid base that is easily desorbed on the surface of the fine particles of the oil phase is small.

[0012] In addition, even when the emulsion obtained by passing the fluid obtained by merging the liquid oil phase containing a sphingoid base and a solid fat and the liquid aqueous phase containing water and an acid through pores is mixed with one or more of a polycarboxylic acid compound and its salt and an aromatic carboxylic acid compound and its salt (hereinafter also referred to as "carboxylic acid compounds A"), an emulsion excellent in storage stability can be obtained. This is considered to be because the fine particles obtained by the above method for producing an emulsion have a sphingoid base incorporated into the fine particles and a small amount of the sphingoid base on the surface of the fine particles, so that the carboxylic acid compounds A can be combined with the sphingoid base to suppress the detachment and aggregation of the sphingoid base from the fine particles.

[0013] The method for producing an emulsion of the present invention includes a merging step of flowing a liquid oil phase and a liquid aqueous phase containing water and an acid, respectively, and merging them, and a pore flow step of passing the fluid obtained by merging the oil phase and the aqueous phase in the merging step through pores.

[0014] Hereinafter, each component will be described in detail.

[0015] <Oil phase> Examples of the sphingoid base contained in the oil phase include long-chain aliphatic amines having a hydroxy group represented by the following general formula (1). Note that sphingolipids (ceramides bonded to fatty acids via amide bonds) are not included in the sphingoid base.

[0016]

Chemical formula

[0017] (In the formula, R 1 represents a linear or branched saturated or unsaturated hydrocarbon group having 4 to 30 carbon atoms, R 2 and R 3 each independently represent a hydrogen atom, a hydroxyl group, a hydroxymethyl group, or an acetoxymethyl group, X 1 , X 2 and X 3 each independently represent a hydrogen atom, a hydroxyl group, or an acetoxy group, Y represents a methylene group or a methine group (however, when Y is a methine group, either one of X 1 and X 2 is a hydrogen atom, and the other does not exist.), and the dashed line indicates that an unsaturated bond may be present.)

[0018] R 1 The number of carbon atoms of is preferably 8 or more, more preferably 10 or more, preferably 22 or less, and more preferably 18 or less from the viewpoint of obtaining a dispersion having excellent storage stability. R 2 and R 3 are each independently preferably a hydrogen atom or a hydroxymethyl group from the same viewpoint as above. X 1 , X 2 and X 3 are each independently preferably a hydrogen atom or a hydroxyl group from the same viewpoint as above.

[0019] From the perspective of obtaining a dispersion with excellent storage stability, the sphingoid base preferably contains one or more of the long-chain aliphatic amines having a hydroxy group represented by the above general formula (1), and more preferably contains one or more of sphingosine of the following formula (2), dihydrosphingosine of the following formula (3), and phytosphingosine of the following formula (4).

[0020]

Chemical formula

[0021] From the perspective of manufacturing a composition such as a cosmetic containing a large amount of sphingoid base and obtaining a dispersion with excellent storage stability, the content of the sphingoid base in the oil phase is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 2% by mass or more, and from the perspective of keeping the manufacturing cost low, it is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less.

[0022] The solid fat contained in the oil phase has a melting point of 30°C or higher. From the perspective of enhancing the stability of the sphingoid base and obtaining a dispersion with excellent storage stability, the melting point of the solid fat is preferably 40°C or higher, more preferably 50°C or higher, and from the perspective of ease of manufacturing the dispersion, it is preferably 160°C or lower, more preferably 120°C or lower, still more preferably 100°C or lower, and even more preferably 90°C or lower. The melting point of the solid fat is measured by the first method, the second method, or the third method of the general test method for quasi-drug raw material specifications. The first method is used when the melting point exceeds 75°C, the second method is used when the melting point is 50°C or higher and 75°C or lower, and the third method is used when the melting point is less than 50°C.

[0023] From the viewpoint of obtaining a dispersion with excellent storage stability, the solid fat is preferably a compound that is hardly soluble in water. Therefore, the solubility of the solid fat in 100 g of water at 25 °C (1013.25 hPa) is preferably 100 mg / 100 g or less, more preferably 10 mg / 100 g or less, still more preferably 1 mg / 100 g or less, and even more preferably 0.1 mg / 100 g or less. Note that the lower limit of the solubility is 0 mg / 100 g, that is, it is insoluble. The solubility of the solid fat is measured by the method described in Journal of the Chemical Society of Japan, 1985, No. 11, p2116 - 2119 and 1982, No. 11, p1830 - 1834.

[0024] Examples of the solid fat include alcohols containing sterols, esters, ethers, hydrocarbons, etc. The solid fat preferably contains one or more of these.

[0025] When the solid fat is an alcohol, ester or ether, from the viewpoint of obtaining a dispersion with excellent storage stability, it preferably has a monovalent hydrocarbon group. From the viewpoint of obtaining a dispersion with excellent storage stability, the number of carbon atoms of the monovalent hydrocarbon group possessed by these solid fats is preferably 14 or more, more preferably 16 or more, still more preferably 18 or more, and from the viewpoint of ease of manufacturing the dispersion, it is preferably 30 or less, more preferably 22 or less. The monovalent hydrocarbon group possessed by the solid fat is preferably a saturated hydrocarbon group from the viewpoint of obtaining a dispersion with excellent storage stability. The monovalent hydrocarbon group possessed by the solid fat may be either linear or branched.

[0026] Note that the monovalent hydrocarbon group is a functional group formed by removing one hydrogen atom from a hydrocarbon. In the case of an alcohol, the monovalent hydrocarbon group means the hydrocarbon group bonded to the hydroxyl group, in the case of an ester, it means the hydrocarbon group derived from a carboxylic acid or the hydrocarbon group derived from an alcohol, and in the case of an ether, it means the hydrocarbon group bonded to the oxygen atom.

[0027] When the solid fat contains alcohol, from the viewpoint of obtaining a dispersion with excellent storage stability, the number of carbon atoms of the alcohol is preferably 14 or more, more preferably 16 or more, still more preferably 18 or more, and from the viewpoint of ease of manufacturing the dispersion, it is preferably 30 or less, more preferably 22 or less. The alcohol preferably contains a linear or branched monohydric alcohol from the viewpoint of obtaining a dispersion with excellent storage stability, and a linear monohydric alcohol is preferred. Examples of the linear or branched monohydric alcohol include cetyl alcohol, stearyl alcohol, behenyl alcohol, etc., and the preferred number of carbon atoms is as described above. The alcohol preferably contains one or more of these.

[0028] From the viewpoint of obtaining a dispersion with excellent storage stability, the solid fat preferably contains sterols which are a kind of alcohol. When the solid fat contains sterols, since sterols and sphingoid bases have an affinity, an effect of suppressing the desorption of sphingoid bases from the fine particles of the oil phase is expected. Examples of sterols include animal-derived sterols, plant-derived sterols, etc. Examples of animal-derived sterols include cholesterol, dihydrocholesterol, cholesteryl succinate, etc. Examples of plant-derived sterols include phytosterol, sitosterol, stigmasterol, campesterol, etc. The sterols preferably contain one or more of these, and more preferably contain cholesterol and / or phytosterol from the viewpoint of producing a dispersion with high storage stability.

[0029] From the viewpoint of obtaining a dispersion with excellent storage stability, the content of sterols in the solid fat is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, and preferably 100% by mass or less.

[0030] The solid fat preferably contains one or more selected from the group consisting of sterols and linear or branched monohydric alcohols.

[0031] From the viewpoint of obtaining a dispersion with excellent storage stability, the total content of sterols and linear or branched monohydric alcohols in the solid fat is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, even more preferably 99% by mass or more, and may be 100% by mass.

[0032] When the solid fat contains an ester, examples of the ester of the solid fat include carboxylic acid esters of monohydric carboxylic acids and monohydric alcohols, carboxylic acid esters of monohydric carboxylic acids and polyhydric alcohols, polyhydric carboxylic acid esters of polyhydric carboxylic acids and monohydric alcohols, and the like. The ester of the solid fat preferably contains one or more of these, and from the viewpoint of obtaining a dispersion with excellent storage stability, it is more preferable to contain a carboxylic acid ester of a monohydric carboxylic acid and a monohydric alcohol and / or a carboxylic acid ester of a monohydric carboxylic acid and a polyhydric alcohol. Specifically, examples of the ester of a monohydric carboxylic acid and a monohydric alcohol include cetyl palmitate, stearyl stearate, behenyl behenate, and the like. Examples of the ester of a monohydric carboxylic acid and a polyhydric alcohol include glyceryl monostearate, pentaerythritol tetrastearate, and the like.

[0033] Examples of the raw material alcohol for the ester of the solid fat include monohydric alcohols and polyhydric alcohols. The number of carbon atoms of the monohydric alcohol is preferably 1 or more and 30 or less, more preferably 8 or more and 30 or less, still more preferably 12 or less and 22 or less, even more preferably 14 or more and 22 or less, even more preferably 16 or more and 22 or less, and even more preferably 18 or more and 22 or less, from the viewpoints of obtaining a dispersion with excellent storage stability and ease of production of the dispersion. Examples of the polyhydric alcohol include glycerin, propylene glycol, trimethylolpropane, pentaerythritol, sorbitol, sucrose, and the like.

[0034] Examples of the raw material carboxylic acids of the esters of the solid fat include monocarboxylic acids and polycarboxylic acids. Examples of the monocarboxylic acids include monovalent fatty acids and the like. From the viewpoints of obtaining a dispersion excellent in storage stability and ease of production of the dispersion, the number of carbon atoms of the monocarboxylic acid is preferably 1 or more and 30 or less, more preferably 8 or more and 30 or less, still more preferably 12 or more and 22 or less, even more preferably 14 or more and 22 or less, even more preferably 16 or more and 22 or less, and even more preferably 18 or more and 22 or less. Examples of the polycarboxylic acids include adipic acid, terephthalic acid, trimellitic acid and the like.

[0035] When the solid fat contains an ether, from the viewpoint of obtaining a dispersion excellent in storage stability, the number of carbon atoms of the ether is preferably 25 or more, more preferably 30 or more, and still more preferably 35 or more, and from the viewpoint of ease of production of the dispersion, it is preferably 200 or less, more preferably 100 or less, still more preferably 80 or less, and even more preferably 60 or less. Examples of the ether of the solid fat include dialkyl ethers such as distearyl ether.

[0036] When the solid fat contains a hydrocarbon, from the viewpoint of obtaining a dispersion excellent in storage stability, the number of carbon atoms of the hydrocarbon is preferably 21 or more, more preferably 25 or more, and still more preferably 30 or more, and from the viewpoint of ease of production of the dispersion, it is preferably 200 or less, more preferably 100 or less, still more preferably 80 or less, and even more preferably 60 or less. Examples of the hydrocarbon of the solid fat include alkanes, paraffins and the like. Examples of the paraffin include paraffin wax 140, paraffin wax 9ND and the like.

[0037] From the viewpoint of obtaining a dispersion excellent in storage stability, the content of the solid fat in the oil phase is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 7% by mass or more, and from the viewpoint of keeping the production cost low, it is preferably 25% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less. In addition, the preferable content of the sterols in the oil phase when the oil phase contains sterols is the same as this.

[0038] From the viewpoint of obtaining a dispersion with excellent storage stability, the molar ratio of the solid fat in the oil phase to the sphingoid base is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.8 or more, and even more preferably 0.9 or more. From the same viewpoint as above, it is preferably 3 or less, more preferably 2 or less, still more preferably 1.5 or less. In addition, the preferred molar ratio of sterols in the oil phase to the sphingoid base when the oil phase contains sterols is the same as this.

[0039] The oil phase may contain a liquid oil having a melting point of less than 30°C. From the viewpoints of obtaining a dispersion with excellent storage stability and using it in low-viscosity cosmetics, etc., the content of the liquid oil in the oil phase is preferably 3% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less. From the same viewpoint as above, the content of the liquid oil in the dispersion to be produced is preferably 0.03% by mass or less, more preferably 0.01% by mass or less. The melting point of the liquid oil is measured by the third method of the general test method for quasi-drug raw materials.

[0040] Examples of the liquid oil that the oil phase can contain include alcohols, esters, ethers, hydrocarbons, etc. From the viewpoint of having less hindrance to obtaining a dispersion with excellent storage stability, the liquid oil preferably contains an ester. Examples of the ester of the liquid oil include carboxylic acid esters of monovalent carboxylic acids and monohydric alcohols, carboxylic acid esters of monovalent carboxylic acids and polyhydric alcohols, polyvalent carboxylic acid esters of polyvalent carboxylic acids and monohydric alcohols, etc. Specific examples of the ester of the liquid oil include isopropyl myristate, butyl myristate, isopropyl palmitate, decyl oleate, oleyl oleate, octyldodecyl oleate, glyceryl tri(caprylate / caprate), glyceryl triisostearate, diglyceryl triisostearate, glyceryl tricaprylate, etc. The ester of the liquid oil preferably contains one or more of these.

[0041] The oil phase may contain a water-soluble solvent from the perspective of dissolving solid fat and obtaining a dispersion with excellent storage stability. From the same perspective as above, the dissolution amount of the water-soluble solvent in 100 g of water at 20°C is preferably 50 g or more, more preferably 100 g or more.

[0042] Examples of the water-soluble solvent include alcohols, ketones, ethers, etc. Examples of the alcohols include monohydric alcohols, dihydric alcohols, trihydric alcohols, etc. From the perspective of producing a dispersion with high storage stability, the number of carbon atoms of the alcohols is preferably 2 or more and 12 or less, more preferably 2 or more and 6 or less. The water-soluble solvent preferably contains one or more of these, and from the same perspective as above, it is more preferable to contain one or more of the alcohols, still more preferable to contain one or more of the dihydric alcohols, even more preferably to contain one or more of the dihydric alcohols having 2 or more and 12 or less carbon atoms, and even more preferably to contain 1,2-pentanediol and / or dipropylene glycol.

[0043] From the perspective of obtaining a dispersion with excellent storage stability, the content of the water-soluble solvent in the oil phase is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and from the same perspective as above, it is preferably 99% by mass or less, more preferably 95% by mass or less, still more preferably 90% by mass or less.

[0044] In addition, the oil phase may contain, for example, cosmetic ingredients such as ultraviolet absorbers, vitamins, preservatives, pigments, fragrances, and medicinal ingredients.

[0045] <Aqueous phase> The aqueous phase contains water and an acid. Examples of the acid include organic acids and inorganic acids. Examples of the organic acid include trimethylglycine, lactic acid, acetic acid, etc. Examples of the inorganic acid include hydrochloric acid, nitric acid, etc. From the viewpoint of obtaining a dispersion with excellent storage stability, the acid is preferably a monovalent acid. The acid serves as a counter ion for the sphingoid base. The molar equivalent ratio of the acid to the sphingoid base (acid / sphingoid base) is preferably 0.7 or more, more preferably 0.8 or more, preferably 1.3 or less, and more preferably 1.2 or less from the same viewpoint as above.

[0046] In addition, the aqueous phase may contain water-soluble components such as, for example, a pH adjuster, a water-soluble solvent, a preservative, etc.

[0047] Therefore, from the viewpoint of obtaining a dispersion with excellent storage stability, it is preferable that neither the oil phase nor the aqueous phase, nor the dispersion to be produced, substantially contains a surfactant other than the sphingoid base. In the method for producing a dispersion according to the embodiment, a sphingoid base is used as the surfactant, and a dispersion with excellent storage stability can be easily produced without using other surfactants. Here, in the present application, "substantially does not contain a surfactant other than the sphingoid base" means that the content of the surfactant other than the sphingoid base in the oil phase, the aqueous phase, or the dispersion to be produced is 0.5% by mass or less. In this case, the content of the surfactant other than the sphingoid base in the oil phase, the aqueous phase, or the dispersion is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.01% by mass or less, and even more preferably 0% by mass. When the surfactant other than the sphingoid base contains a salt, the content of the surfactant other than the sphingoid base includes the content of the salt.

[0048] Examples of surfactants other than sphingoid bases include, for example, anionic surfactants having a hydrocarbon group with 8 to 24 carbon atoms, cationic surfactants having a hydrocarbon group with 8 to 24 carbon atoms, nonionic surfactants having a hydrocarbon group with 8 to 24 carbon atoms, amphoteric surfactants having a hydrocarbon group with 8 to 24 carbon atoms, and polymeric surfactants having a hydrophobic moiety with a hydrocarbon group having 8 to 24 carbon atoms and a nonionic or ionic hydrophilic moiety such as polyoxyethylene, vinylpyrrolidone, anionic, cationic, etc.

[0049] Examples of anionic surfactants having a hydrocarbon group with 8 to 24 carbon atoms include fatty acid salts with 8 to 24 carbon atoms such as sodium laurate, potassium laurate, and potassium palmitate; polyoxyethylene alkyl ether carboxylates such as sodium polyoxyethylene tridecyl ether acetate; alkyl phosphates such as potassium lauryl phosphate, sodium lauryl phosphate, arginine lauryl phosphate, potassium myristyl phosphate, sodium myristyl phosphate, arginine myristyl phosphate, potassium palmityl phosphate, sodium palmityl phosphate, and arginine palmityl phosphate; polyoxyethylene alkyl ether phosphates such as sodium polyoxyethylene oleyl ether phosphate and sodium polyoxyethylene stearyl ether phosphate; alkyl sulfate esters such as sodium lauryl sulfate and potassium lauryl sulfate; polyoxyethylene alkyl ether sulfate esters such as potassium polyoxyethylene lauryl sulfate, sodium polyoxyethylene lauryl sulfate, and triethanolamine polyoxyethylene lauryl sulfate; acylated amino acid salts such as sodium lauroyl sarcosine, monosodium N-lauroyl glutamate, disodium N-stearoyl glutamate, monosodium N-myristoyl-L-glutamate, triethanolamine N-lauroyl glycine, potassium N-coconut oil fatty acid acyl glycine, triethanolamine N-lauroyl-β-alanine, and triethanolamine N-stearoyl-β-alanine; fatty acid amide sulfonates such as sodium N-myristoyl-N-methyl taurine and sodium N-stearoyl-N-methyl taurine; sulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate, etc.

[0050] Examples of amphoteric surfactants having a hydrocarbon group with 8 to 24 carbon atoms include betaine-based amphoteric surfactants such as lauryldimethylaminoacetic acid betaine, lauroyl amidobetaine, and lauryl sulfobetaine.

[0051] Examples of the nonionic surfactant having a hydrocarbon group with 8 to 24 carbon atoms include sorbitan fatty acid esters such as sorbitan monostearate; polyglycerin fatty acid esters such as glycerin fatty acid ester and polyglyceryl monoisostearate; polyoxyethylene fatty acid esters such as propylene glycol fatty acid ester and polyethylene glycol monolaurate; sucrose fatty acid ester; polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monostearate, and polyoxyethylene coconut oil fatty acid sorbitan; polyoxyethylene alkyl ether; polyoxyethylene sorbitol fatty acid ester; polyoxyethylene glycerin fatty acid ester; polyoxyethylene propylene glycol fatty acid ester; polyoxyethylene castor oil; polyoxyethylene hydrogenated castor oil; polyoxyethylene hydrogenated castor oil fatty acid ester; alkyl polyglucoside; polyoxyalkylene-modified silicones such as polyoxyethylene-methylpolysiloxane copolymer, and the like.

[0052] Examples of the cationic surfactant having a hydrocarbon group with 8 to 24 carbon atoms include tertiary amine compounds and quaternary ammonium salts. As the tertiary amine compound, those formed into salts with organic acids and / or inorganic acids can be used. Examples of the alkyltrimethylammonium salts include octyltrimethylammonium, decyltrimethylammonium chloride, lauryltrimethylammonium chloride, and tetradecyltrimethylammonium chloride; and examples of the dialkyldimethylammonium salts include didecyldimethylammonium chloride and distearyldimethylammonium chloride.

[0053] <Manufacturing Method> Regarding the confluence step of flowing a liquid oil phase and a liquid aqueous phase containing water and an acid, respectively, and then confluencing them, and the pore flow step of flowing the fluid obtained by confluencing the oil phase and the aqueous phase in the confluence step through pores, which are steps of the manufacturing method of the present invention, are shown below.

[0054] FIG. 1 shows an example of a micromixer 10 used for mixing an oil phase and an aqueous phase. This micromixer 10 includes a liquid supply section 11, a constriction mixing section 12 on the downstream side thereof, and a mixed liquid outflow section 13 on the further downstream side.

[0055] The liquid supply section 11 has a double-tube structure in which a small-diameter tube 112 is introduced into a large-diameter tube 111 and they are coaxially provided. The gap between the large-diameter tube 111 and the small-diameter tube 112 is configured as a first liquid flow path P1 through which a first liquid L1 flows. The inside of the small-diameter tube 112 is configured as a second liquid flow path P2 through which a second liquid L2 flows. A first liquid inlet portion 111a provided at the upstream end of the large-diameter tube 111 is connected to a first liquid supply source (not shown). The small-diameter tube 112 is connected to a second liquid supply source (not shown).

[0056] The inside of the downstream end portion of the large-diameter tube 111 is formed in a bowl shape with an inner diameter gradually decreasing toward the downstream side, and the outside of the downstream end portion of the small-diameter tube 112 is formed in a hemispherical shape with an outer diameter gradually decreasing toward the downstream side, and the gap between them constitutes a part of the first liquid flow path P1. The downstream end portion of the second liquid flow path P2 inside the small-diameter tube 112 is formed in a bowl shape with an inner diameter gradually decreasing toward the downstream side. A second liquid outflow hole 112a extending in the axial direction, that is, along the flow direction of the second liquid L2, is formed at the downstream end of the small-diameter tube 112. This second liquid outflow hole 112a communicates the first liquid flow path P1 and the second liquid flow path P2.

[0057] In the constriction mixing section 12, a pore 121 extending coaxially with the second liquid outflow hole 112a, that is, along the flow direction of the second liquid L2, is formed. This pore 121 communicates the liquid supply section 11 and the mixed liquid outflow section 13.

[0058] The inner diameter d of the pore 121 is preferably 0.03 mm or more, more preferably 0.05 mm or more, still more preferably 0.1 mm or more, from the viewpoint of obtaining high productivity, and preferably 20 mm or less, more preferably 10 mm or less, still more preferably 7 mm or less, still more preferably 5 mm or less, still more preferably 3 mm or less, still more preferably 1 mm or less, from the viewpoint of obtaining high miscibility. The inner diameter d of the pore 121 is preferably smaller than the inner diameter D of the second liquid outflow hole 112a. When the flow path cross-sectional shapes of the pore 121 and / or the second liquid outflow hole 112a are non-circular, their inner diameters d and D are hydraulic diameters.

[0059] The length l of the pore 121 is preferably 0.05 mm or more, more preferably 0.1 mm or more, still more preferably 0.3 mm or more, from the viewpoint of obtaining high miscibility, and preferably 30 mm or less, more preferably 15 mm or less, still more preferably 10 mm or less, still more preferably 5 mm or less, still more preferably 1 mm or less, from the viewpoint of obtaining high productivity.

[0060] The ratio (l / d) of the length l of the pore 121 to the inner diameter d is preferably 0.10 or more, more preferably 0.50 or more, still more preferably 1 or more, from the viewpoint of high miscibility, and preferably 10 or less, more preferably 5 or less, still more preferably 3 or less, from the viewpoint of high productivity.

[0061] Inside the mixed liquid outflow part 13, a mixed liquid flow path P3 is formed which expands in a conical hole shape toward the downstream side and then continues to be formed in a cylindrical hole shape. The mixed liquid outflow part 13 is connected to a mixed liquid recovery part (not shown).

[0062] In this micromixer 10, in the liquid supply unit 11, the first liquid L1 flows in the first liquid flow path P1 toward the downstream side, and the second liquid L2 flows in the second liquid flow path P2 toward the downstream side. The first liquid L1 and the second liquid L2 merge in the vicinity of the outlet of the second liquid outlet hole 112a such that the first liquid L1 surrounds the second liquid L2 flowing out from the second liquid outlet hole 112a from all around. The merged liquid of the first liquid L1 and the second liquid L2 is mixed by flowing through the pores 121 in the constriction mixing unit 12. The mixed liquid L3 of the first liquid L1 and the second liquid L2 flowing out from the pores 121 flows out into the mixed liquid flow path P3 in the mixed liquid outlet unit 13.

[0063] In the method for producing a dispersion according to the embodiment, this micromixer 10 is used, and one of the liquid oil phase and the liquid water phase is used as the first liquid L1 and the other is used as the second liquid L2. The oil phase and the water phase flow and merge in the micromixer 10 (merging step), and then, the fluid obtained by their merging flows through the pores 121 (pore flow-through step). At this time, the oil phase and the water phase are mixed and emulsified to form an oil-in-water type dispersion in which fine particles of the oil phase are dispersed in the water phase. From the viewpoint of obtaining a dispersion having excellent storage stability, it is preferable to use the oil phase as the first liquid L1 and the water phase as the second liquid L2, and for the oil phase to merge so as to surround the water phase from all around.

[0064] The inlet temperature of the oil phase to the micromixer 10, that is, the temperature of the oil phase before merging with the water phase, is preferably equal to or higher than the dissolution temperature of the oil phase from the viewpoints of smoothly flowing the oil phase and obtaining a dispersion having excellent storage stability. Specifically, it is preferably 60°C or higher, more preferably 70°C or higher, still more preferably 75°C or higher, and from the viewpoint of obtaining a dispersion having excellent storage stability, it is preferably 120°C or lower, more preferably 100°C or lower, still more preferably 90°C or lower, and still more preferably 85°C or lower.

[0065] The inlet temperature of the aqueous phase to the micro mixer 10, that is, the temperature of the aqueous phase before it merges with the oil phase, is preferably lower than the temperature of the oil phase before it merges with the aqueous phase. From the perspective of suppressing the precipitation of the oil phase due to a sharp temperature drop and obtaining a dispersion with excellent storage stability, it is preferably 60 °C or higher, more preferably 70 °C or higher, still more preferably 75 °C or higher. From the perspective of obtaining a dispersion with excellent storage stability, it is preferably 120 °C or lower, more preferably 100 °C or lower, still more preferably 90 °C or lower, and even more preferably 85 °C or lower.

[0066] The total flow rate of the fluid formed by merging the oil phase and the aqueous phase mixed in the micro mixer 10 is preferably 50 g / min or more, more preferably 70 g / min or more, still more preferably 90 g / min or more from the perspective of obtaining a dispersion with excellent storage stability. From the same perspective as above, it is preferably 42000 g / min or less, more preferably 25000 g / min or less, still more preferably 17000 g / min or less.

[0067] The flow rate ratio of the oil phase to the aqueous phase (oil phase / aqueous phase) mixed in the micro mixer 10 is preferably 3 / 117 or more, more preferably 5 / 115 or more, still more preferably 7 / 113 or more from the perspective of obtaining a dispersion with excellent storage stability. From the same perspective as above, it is preferably 20 / 100 or less, more preferably 15 / 105 or less, still more preferably 10 / 110 or less. Note that this flow rate is the mass of the oil phase or the aqueous phase moving per unit time.

[0068] The shear rate when the fluid formed by merging the liquid oil phase and the aqueous phase containing water and an acid is passed through the pores (shear rate in the pores of the micro mixer 10) is preferably 3000 s -1 or more, even more preferably 5000 s -1 or more, even more preferably 10000 s -1 or more from the perspective of manufacturing a dispersion with excellent storage stability. From the perspective of reducing the device load, it is preferably 300000 s -1 or less, more preferably 200000 s -1 or less, still more preferably 100000 s -1It is as follows. This shear rate is calculated by dividing the linear velocity of the combined fluid by the inner diameter of the nozzle (linear velocity / inner diameter of the nozzle). The linear velocity is obtained by flow rate / pore area.

[0069] In the above embodiment, the micromixer 10 having a double-tube structure is used, but it is not particularly limited thereto, and micromixers 20 and 30 having a T-tube structure as shown in FIGS. 2 and 3 may also be used.

[0070] In the micromixer 20 having a T-tube structure shown in FIG. 2, one side of the main pipe is configured as the first liquid supply part 21 and the other side is configured as the second liquid supply part 22, and their interiors are respectively configured as the first liquid flow path P1 and the second liquid flow path P2. The tip flow side portion of the branch pipe is configured as the mixed liquid outflow part 23, and its interior is configured as the mixed liquid flow path P3. Fine pores 24 are formed inside the base end side portion of the branch pipe. The fine pores 24 communicate the first liquid flow path P1 and the second liquid flow path P2 with the mixed liquid flow path P3. In this micromixer 20, the first liquid L1 flowing through the first liquid flow path P1 of the first liquid supply part 21 and the second liquid L2 flowing through the second liquid flow path P2 of the second liquid supply part 22 collide head-on and merge, and their merged product flows through the fine pores 24 extending in a direction orthogonal to the flow directions of the first liquid L1 and the second liquid L2 and is mixed.

[0071] In the micromixer 30 having a T-tube structure shown in FIG. 3, one side of the main pipe is configured as the first liquid supply part 31 and the branch pipe is configured as the second liquid supply part 32, and their interiors are respectively configured as the first liquid flow path P1 and the second liquid flow path P2. The tip side portion of the other side of the main pipe is configured as the mixed liquid outflow part 33, and its interior is configured as the mixed liquid flow path P3. Fine pores 34 are formed inside the base end side portion of the other side of the main pipe. The fine pores 34 communicate the first liquid flow path P1 and the second liquid flow path P2 with the mixed liquid flow path P3. In this micromixer 30, the second liquid L2 flowing through the second liquid flow path P2 of the second liquid supply part 22 collides with and merges into the first liquid L1 flowing through the first liquid flow path P1 of the first liquid supply part 31 from the orthogonal direction, and their merged product flows through the fine pores 34 extending in the flow direction of the first liquid L1 and is mixed.

[0072] <Dispersion liquid> The dispersion liquid produced by the above production method is shown below.

[0073] From the viewpoints of producing a composition such as a cosmetic containing a large amount of sphingoid base and obtaining a dispersion liquid with excellent storage stability, the content of sphingoid base in the produced dispersion liquid is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more, and from the viewpoint of keeping the production cost low, it is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less.

[0074] From the viewpoint of obtaining a dispersion liquid with excellent storage stability, the content of solid fat in the produced dispersion liquid is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more, and from the viewpoint of keeping the production cost low, it is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less. In addition, the preferable content of sterols in the produced dispersion liquid when the oil phase contains sterols is the same as this.

[0075] From the viewpoint of obtaining a dispersion liquid with excellent storage stability, the molar ratio of solid fat to sphingoid base in the produced dispersion liquid is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.9 or more, and from the same viewpoints as above, it is preferably 3 or less, more preferably 2 or less, still more preferably 1.5 or less. In addition, the preferable molar ratio of sterols to sphingoid base in the produced dispersion liquid when the oil phase contains sterols is the same as this.

[0076] From the viewpoint of obtaining a dispersion liquid with excellent storage stability, the content of the water-soluble solvent derived from the oil phase in the produced dispersion liquid is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and from the same viewpoints as above, it is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less.

[0077] From the perspective of obtaining a dispersion with excellent storage stability and improving transparency when formulated in cosmetics, the average particle diameter of the oil phase in the produced dispersion is preferably 200 nm or less, more preferably 180 nm or less, still more preferably 150 nm or less. From the perspective of ease of manufacturing the dispersion, it is preferably 10 nm or more, more preferably 30 nm or more, still more preferably 50 nm or more. This average particle diameter of the oil phase is determined based on the cumulant method analysis by the dynamic light scattering method described in the examples below.

[0078] From the perspective of obtaining a dispersion with excellent storage stability, the pH of the produced dispersion is preferably 3.5 or more, more preferably 3.8 or more, still more preferably 4.0 or more. From the perspective of ease of manufacturing the dispersion, it is preferably 5.5 or less, more preferably 5.0 or less, still more preferably 4.8 or less. This pH of the dispersion is measured using a pH meter for the dispersion at 20°C.

[0079] From the perspective of obtaining a dispersion with excellent storage stability, the viscosity of the produced dispersion is preferably 0.5 mPa·s or more, more preferably 1.0 mPa·s or more, still more preferably 1.5 mPa·s or more. From the perspective of using it in low-viscosity cosmetics, it is preferably 3.0 mPa·s or less, more preferably 2.5 mPa·s or less, still more preferably 2.0 mPa·s or less.

[0080] The present invention is also a method for producing an oil-in-water type dispersion containing a sphingoid base and carboxylic acid compounds A, including the following steps 1 and 2. Step 1: A step of obtaining an oil-in-water type dispersion by flowing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30°C or higher and a liquid water phase containing water and an acid, respectively, and then merging them, and a step of flowing the fluid obtained by merging the oil phase and the water phase in the merging step through pores. Step 2: A step of mixing the dispersion obtained in Step 1 with carboxylic acid compounds A.

[0081] For Process 1, it is as described above. Similarly, for the dispersion obtained in Process 1, it is as described above.

[0082] The present invention has Process 2 of mixing the dispersion obtained in Process 1 with carboxylic acid compounds A.

[0083] Thereby, for example, a dispersion useful for cosmetics and the like can be produced.

[0084] There is no limitation on the mixing method. The carboxylic acid compounds A may be added to the dispersion, or vice versa. The mixing temperature is preferably 0°C or higher, more preferably 10°C or higher, and preferably 50°C or lower, more preferably 30°C or lower from the viewpoint of the stability of the dispersion.

[0085] The polyvalent carboxylic acid compound and / or its salt is a compound having two or more carboxyl groups and / or its salt, and is, for example, used as a pH adjuster or a chelating agent in a composition such as cosmetics. The aromatic carboxylic acid compound and / or its salt is, for example, used as a preservative or an extract in a composition such as cosmetics.

[0086] Examples of the polyvalent carboxylic acid compound include organic acids and inorganic acids. Examples of the organic acid include succinic acid, citric acid, adipic acid, ethylenediaminetetraacetic acid, etc. Examples of the inorganic acid include phosphoric acid, etc. Examples of the salt include alkali metal salts such as sodium salts, etc. Examples of the aromatic carboxylic acid compound include components contained in extracts such as benzoic acid used as a preservative, gallic acid contained in gallnut extract, and gallic acid contained in cinnamon extract, etc. As the salt, alkali metal salts such as sodium are preferred. The carboxylic acid compounds A preferably contain one or more of these.

[0087] When mixing carboxylic acid compounds A into the dispersion, the total amount of carboxylic acid compounds A relative to 100 parts by mass of the sphingoid base varies depending on the use such as cosmetics, but is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and from the viewpoint of obtaining a dispersion excellent in storage stability, is preferably 20 parts by mass or less, more preferably 10 parts by mass or less.

[0088] In the dispersion obtained by the production method of the present invention, the total content of carboxylic acid compounds A varies depending on the use such as cosmetics, but is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and from the viewpoint of improving the storage stability of the dispersion, is preferably 1% by mass or less, more preferably 0.7% by mass or less.

[0089] The present invention includes the following aspects.

[0090] 〔1〕A method for producing an oil-in-water type dispersion containing a sphingoid base, including the following step 1. Step 1: A step of flowing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30°C or higher and a liquid water phase containing water and an acid, respectively, and a step of combining them, and a step of flowing the fluid obtained by combining the oil phase and the water phase in the combining step through pores to obtain an oil-in-water type dispersion.

[0091] 〔2〕The method for producing a dispersion according to 〔1〕, wherein the sphingoid base includes a compound represented by the following general formula (1).

[0092]

Chemical formula

[0093] (In the formula, R 1 represents a linear or branched saturated or unsaturated hydrocarbon group having 4 to 30 carbon atoms, R 2 and R 3 each independently represent a hydrogen atom, a hydroxyl group, a hydroxymethyl group or an acetoxymethyl group, X 1 , X2 and X 3 each independently represents a hydrogen atom, a hydroxyl group or an acetoxy group, Y represents a methylene group or a methine group (however, when Y is a methine group, one of X 1 and X 2 is a hydrogen atom, and the other does not exist.), and the dashed line indicates that it may be an unsaturated bond.)

[0094] [3] The method for producing a dispersion according to [1] or [2], wherein the content of the liquid oil having a melting point of less than 30°C in the oil phase is 1% by mass or less.

[0095] [4] The method for producing a dispersion according to any one of [1] to [3], wherein the solid fat contains sterols, and the content of sterols in the solid fat is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0096] [5] The method for producing a dispersion according to any one of [1] to [4], wherein the molar ratio of the solid fat in the oil phase to the sphingoid base is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.8 or more, even more preferably 0.9 or more, and preferably 3 or less.

[0097] [6] The method for producing a dispersion according to any one of [1] to [5], wherein the content of the sphingoid base in the dispersion is 0.05% by mass or more and 5% by mass or less.

[0098] [7] The method for producing a dispersion according to any one of [1] to [6], wherein the dispersion does not substantially contain a surfactant other than the sphingoid base.

[0099] [8] The method for producing a dispersion according to any one of [1] to [7], wherein the acid is a monovalent acid.

[0100] 〔9〕The method for producing a dispersion according to any one of 〔1〕to 〔8〕, wherein the average particle diameter of the oil phase in the dispersion is 200 nm or less.

[0101] 〔10〕A method for producing an oil-in-water type dispersion containing one or more of a sphingoid base, a polyvalent carboxylic acid compound and its salt, and an aromatic carboxylic acid compound and its salt, including the following steps 1 and 2. Step 1: A step of obtaining an oil-in-water type dispersion by flowing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30 °C or higher and a liquid aqueous phase containing water and an acid, respectively, and merging them, and a step of flowing the fluid obtained by merging the oil phase and the aqueous phase in the merging step through pores. Step 2: A step of mixing the dispersion obtained in Step 1 with one or more of a polyvalent carboxylic acid compound and its salt and an aromatic carboxylic acid compound and its salt.

[0102] 〔11〕The method for producing a dispersion according to 〔10〕, wherein the polyvalent carboxylic acid compound and / or its salt contains one or more of ethylenediaminetetraacetic acid, citric acid, phosphoric acid, and their salts.

Example

[0103] (Dispersion production apparatus) A micromixer having the same structure as that shown in Fig. 1 was prepared. The inner diameter of the pores was 0.6 mm, the length was 1.5 mm, and the ratio of the length to the inner diameter was 2.5. The first liquid inlet of the large-diameter tube of this micromixer was connected to an oil-phase storage tank via an oil-phase supply line, the small-diameter tube was connected to an aqueous-phase storage tank via an aqueous-phase supply line, and the mixed-liquid outlet was connected to a dispersion recovery tank via a dispersion recovery line to construct a dispersion production apparatus.

[0104] A heat exchanger for controlling the temperature of the oil phase supplied to the micromixer was provided at the connection part with the micromixer in the oil phase supply line. Similarly, a heat exchanger for controlling the temperature of the aqueous phase supplied to the micromixer was provided at the connection part with the micromixer in the aqueous phase supply line.

[0105] (Oil phase and aqueous phase) The oil phases having the compositions shown in Tables 1A and B used in each of Examples 1 to 8 and Comparative Examples 1 to 2 were prepared. The materials used for the preparation of the oil phase were phytosphingosine (manufactured by Evonik), cholesterol (manufactured by JSQI Nippon Seika Co., Ltd., melting point: 148 to 150°C, solubility in water (25°C): 0.1 mg / 100 g or less), phytosterol (Phytosterol-S, manufactured by Tama Seikagaku Co., Ltd., melting point 131 to 146°C, solubility in water (25°C): 0.1 mg / 100 g or less), stearyl alcohol (manufactured by Kao Corporation, melting point 59.4 to 59.8°C, solubility in water (25°C): 0.1 mg / 100 g or less), glyceryl monostearate (manufactured by Kao Corporation, melting point 62 to 68°C, solubility in water (25°C): 0.1 mg / 100 g or less), dipropylene glycol (DPG-RF, manufactured by ADEKA), and 1,2-pentanediol (Hydrolite 5 green, manufactured by Symrise AG).

[0106] The aqueous phases having the compositions shown in Tables 1A and B used in each of Examples 1 to 8 and Comparative Examples 1 to 2 were prepared. The materials used for the preparation of the aqueous phase were lactic acid (manufactured by Musashino Kagaku Kenkyusho Co., Ltd.) and deionized water.

[0107] [Table 1A]

[0108] [Table 1B]

[0109] (Production of dispersion liquid) <Examples 1 to 8> For each of Examples 1 to 8, the oil phase was charged into an oil phase storage tank, and the liquid temperature was adjusted to 80°C. The aqueous phase was charged into an aqueous phase storage tank, and the liquid temperature was maintained at room temperature. Then, the oil phase and the aqueous phase were supplied to a micromixer to produce a dispersion. At this time, as shown in Table 2, the total flow rate of the oil phase and the aqueous phase was 120 g / min, and the flow rate of each of the oil phase and the aqueous phase was controlled so as to be a predetermined value. The inlet temperature of the oil phase to the micromixer, that is, the temperature of the oil phase before merging with the aqueous phase, was controlled to 85°C by a heat exchanger. The inlet temperature of the aqueous phase to the micromixer, that is, the temperature of the aqueous phase before merging with the oil phase, was controlled to 80°C by a heat exchanger. Note that the temperature of the dispersion flowing out from the micromixer was not controlled.

[0110]

Table 2

[0111] <Comparative Example 1> The temperature of the oil phase was controlled to 85°C and the temperature of the aqueous phase was controlled to 80°C respectively. After mixing them, a solution was obtained by stirring and mixing for 15 minutes.

[0112] <Comparative Example 2> The temperature of the oil phase was controlled to 85°C and the temperature of the aqueous phase was controlled to 80°C respectively. After mixing them, preliminary emulsification was carried out by mixing at a rotation speed of 8000 r / min for 15 minutes using a homomixer (manufactured by Primix Corporation, TK Robomix). Then, the preliminary emulsion was put into a nanomizer (NM2-L200 manufactured by Yoshida Kikai Kogyo Co., Ltd.), which is a high-pressure emulsifier, and emulsified at a discharge pressure of 100 MPa and a number of passes of 5 times to obtain a dispersion.

[0113] (Test evaluation methods and results) The following various test evaluations were carried out on the dispersions obtained in each of Examples 1 to 8 and Comparative Example 2, and the dispersions obtained by adding an aqueous solution of carboxylic acid compounds A thereto. The results are shown in Table 3. Also, the same test evaluations were carried out on the solutions obtained in Comparative Example 1 and the solutions obtained by adding an aqueous solution of carboxylic acid compounds A thereto.

[0114] <Average particle diameter of the oil phase in the dispersion> For the dispersions obtained in each of Examples 1 to 8 and Comparative Example 2, the average particle diameter of the oil phase was measured by the cumulant method analysis using a laser particle analysis system (ELS-Zneo, manufactured by Otsuka Electronics Co., Ltd.) by the dynamic light scattering method. The measurement conditions were a temperature of 25 °C, an angle of 90° between the incident light and the detector, an integration number of 75 times, and the refractive index of water (1.333) was input as the refractive index of the dispersion solvent. For the measurement sample, the dispersion was weighed into a disposable cup, water was added so that the solid content concentration became 2×10 -4 mass%, and the mixture was stirred at 25 °C. Since what was obtained in Comparative Example 1 was a solution, this measurement was not performed.

[0115] <pH of the dispersion and the solution> For the dispersions obtained in each of Examples 1 to 8 and Comparative Example 2, and the solution obtained in Comparative Example 1, the pH at 20 °C was measured using a pH meter (manufactured by HORIBA).

[0116] <Viscosity of the dispersion> For the dispersions obtained in each of Examples 1 to 3, the viscosity was measured. The viscosity was measured using a B-type viscometer (BL, manufactured by Toki Sangyo Co., Ltd.) at a viscosity (25 °C), rotor No. 1, rotation speed 60 r.p.m., and measurement time 1 minute.

[0117] The results were 1.65 mPa·s for Example 1, 1.98 mPa·s for Example 2, and 1.74 mPa·s for Example 3.

[0118] <Storage stability of the dispersion and the solution> For the dispersions obtained in each of Examples 1 to 8 and Comparative Example 2, they were left standing and stored for 3 months at each temperature of 5 °C, 15 °C, and 40 °C under a nitrogen atmosphere. Then, the average particle diameter of the oil phase in the dispersion was measured, and the change rate from the average particle diameter of the oil phase in the dispersion at the time of production was calculated. And based on that change rate, the evaluation was made as follows: A to D. A: Change rate within 5% B: Increase or decrease in the change rate exceeding 5% to 10% or less C: Increase or decrease with a change rate exceeding 10% and not exceeding 20% D: Increase or decrease with a change rate exceeding 20%

[0119] Regarding the solution obtained in Comparative Example 1, it was allowed to stand and stored for 3 months at each of the temperatures of 5 °C, 15 °C, and 40 °C under a nitrogen atmosphere. Thereafter, the appearance of the solution was visually evaluated as follows: A and D. A: Transparent and no precipitation. D: Precipitation was observed.

[0120] (Production and storage stability of an oil-in-water type dispersion containing a sphingoid base and carboxylic acid compounds A) For the dispersions obtained in Examples 1 to 8 and Comparative Example 2, and the solution obtained in Comparative Example 1, 40 ml was taken into a 40 ml screw tube, and an aqueous solution of disodium ethylenediaminetetraacetate (EDTA-2Na), an aqueous solution of 2-(2-hydroxyethoxy)ethylguanidine succinate (HP50-succinate), an aqueous solution of citric acid, and diethyl ether (diethyl extract ALN (gallic acid content 0.0275% by mass), manufactured by Maruzen Pharmaceutical Co., Ltd.) were added (at 25 °C) and mixed to obtain a dispersion or solution having the composition shown in Table 2.

[0121] After stirring and covering it, it was allowed to stand and stored at a temperature of 20 °C. Then, regarding the storage stability of the dispersion or solution, visual confirmation was performed at intervals over time and evaluated as follows: A to C. A: No precipitation for 1 week or more after production. B: Precipitation was observed within 1 day to 6 days after production. C: Precipitation was observed within 24 hours after production.

[0122] [Table 3]

Industrial Applicability

[0123] The present invention is useful in the technical field of a method for producing a dispersion useful for cosmetics and the like.

Explanation of Symbols

[0124] 10, 20, 30 Micromixers 11 Liquid supply section 111 Large-diameter pipe 111a First liquid inflow section 112 Small-diameter pipe 112a Second liquid outflow hole 12 Constriction mixing section 121, 24, 34 Fine holes 13, 23, 33 Mixed liquid outflow section 21, 31 First liquid supply section 22, 32 Second liquid supply section L1 First liquid L2 Second liquid L3 Mixed liquid P1 First liquid flow path P2 Second liquid flow path P3 Mixed liquid flow path

Claims

1. A method for producing an oil-in-water dispersion containing a sphingoid base, comprising the steps of: Step 1: A step of obtaining an oil-in-water dispersion by flowing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30° C. or higher and a liquid aqueous phase containing water and an acid, respectively, and flowing them together, and a pore flowing step of flowing the fluid obtained by flowing the oil phase and the aqueous phase together in the flowing step through pores.

2. The method for producing a dispersion liquid according to claim 1 , wherein the sphingoid base comprises a compound represented by the following general formula (1): 【Chemistry 1】 (In the formula, R １ represents a linear or branched, saturated or unsaturated hydrocarbon group having 4 to 30 carbon atoms; R ２ and R ３ each independently represents a hydrogen atom, a hydroxyl group, a hydroxymethyl group, or an acetoxymethyl group; X １ , X ２ and X ３ each independently represents a hydrogen atom, a hydroxyl group, or an acetoxy group; Y represents a methylene group or a methine group (provided that when Y is a methine group, X １ and X ２ Either one of the above is a hydrogen atom and the other is absent. ) and the dashed line indicates that the bond may be an unsaturated bond.

3. The method for producing a dispersion liquid according to claim 1 or 2, wherein the content of liquid oil having a melting point of less than 30°C in the oil phase is 1 mass% or less.

4. The method for producing a dispersion liquid according to any one of claims 1 to 3, wherein the solid fat contains a sterol.

5. The method for producing a dispersion according to claim 4 , wherein the solid fat has a sterol content of 80% by mass or more.

6. The method for producing a dispersion according to any one of claims 1 to 5, wherein a molar ratio of the solid fat to the sphingoid base in the oil phase is 0.7 or more.

7. The method for producing a dispersion according to any one of claims 1 to 6, wherein the dispersion is substantially free of any surfactant other than the sphingoid base.

8. The method for producing a dispersion according to any one of claims 1 to 7, wherein the average particle size of the oil phase in the dispersion is 200 nm or less.

9. The method for producing a dispersion liquid according to any one of claims 1 to 8, wherein the acid is a monovalent acid.

10. A method for producing an oil-in-water dispersion containing a sphingoid base and one or more of a polyvalent carboxylic acid compound and its salt, and an aromatic carboxylic acid compound and its salt, comprising the following steps 1 and 2: Step 1: A step of obtaining an oil-in-water dispersion by flowing a liquid oil phase containing a sphingoid base and a solid fat having a melting point of 30° C. or higher and a liquid aqueous phase containing water and an acid, respectively, and flowing them together, and a pore flowing step of flowing the fluid obtained by flowing the oil phase and the aqueous phase together in the flowing step through pores. Step 2: A step of mixing the dispersion obtained in step 1 with one or more of a polycarboxylic acid compound and its salt, and an aromatic carboxylic acid compound and its salt.

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