Method for producing oil-in-water dispersion composition

Abstract

To provide a method for producing an oil-in-water dispersion composition that is easy to mix and has excellent dispersion and emulsion stability, making it easy to maintain a state of an oil-based inner layer that has become oil droplets in a water-based outer layer.SOLUTION: A method for producing an oil-in-water dispersion composition includes a first step for mixing an oil-based inner layer with a thickener and a second step for mixing the oil-based inner layer composition, mixed in the first step, with a water-based outer layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing an oil-in-water dispersion composition. [Background technology]

[0002] Among recent cosmetics, there are emulsified cosmetic products that have thickeners and surfactants added to enhance the stability of the emulsion state.

[0003] Patent Document 1 describes a dispersion composition having an oily inner layer containing a thickener and a surfactant and an aqueous outer layer, and a method for producing the same. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-74660 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to prevent oil-in-water emulsion compositions having an oily inner layer in the form of oil droplets and an aqueous outer layer from returning to a two-layer state (separated state) consisting of the oily inner layer and the aqueous outer layer, a surfactant is added to maintain the emulsified state. An object of the present invention is to provide a method for producing an oil-in-water dispersion composition which is easy to mix and which can easily maintain the state of an oily inner layer in the form of oil droplets in an aqueous outer layer. [Means for solving the problem]

[0006] As a result of extensive research into the above-mentioned problems, the inventors discovered that a manufacturing method comprising a first step of mixing an oily inner layer with a thickener, and a second step of mixing the oily inner layer composition mixed in the first step with an aqueous outer layer, results in a manufacturing method that is easy to mix, has excellent dispersion and emulsion stability, and has completed the present invention.

[0007] To solve the above problems, the method for producing an oil-in-water dispersion composition of the present invention includes a first step of mixing an oily inner layer composition with a thickener, and a second step of mixing the oily inner layer composition mixed in the first step with an aqueous outer layer. A method for producing an oil-in-water dispersion composition, comprising: the viscosity of the aqueous outer layer is 100 to 6000 mPa s, and the viscosity of the oily inner layer is 10 to 5000 mPa s; the specific gravity of the aqueous outer layer is in the range of 0.900 to 1.200, and the specific gravity of the oily inner layer is in the range of 0.900 to 1.200, the ratio of the oily inner layer to the aqueous outer layer (specific gravity of the oily inner layer / specific gravity of the aqueous outer layer) is 0.95 to 1.05; The oil-in-water dispersion composition comprises an oily inner layer made of particles having an average particle radius of 0.1 mm or more, suspended in an aqueous outer layer. It is characterized by the following. According to this method for producing an oil-in-water dispersion composition, the thickener at the interface between the outer aqueous layer and the oil droplets increases the viscosity around the oil droplets, making it easier to maintain the state of the oil droplets in the outer aqueous layer, and providing excellent dispersion and emulsion stability. Furthermore, the generation of stepchildren is suppressed, and the method for producing an oil-in-water dispersion composition that is easy to mix is ​​achieved.

[0008] Furthermore, one embodiment of the method for producing an oil-in-water dispersion composition of the present invention is characterized in that the thickener in the oily mixture is a thickening polymer that is soluble in water and sparingly soluble in ethanol and oil. According to this method for producing an oil-in-water dispersion composition, the thickener at the interface between the outer aqueous layer and the oil droplets increases the viscosity around the oil droplets, making it easier to maintain the state of the oil droplets in the outer aqueous layer, thereby achieving better dispersion and emulsion stability.

[0009] Furthermore, one embodiment of the method for producing an oil-in-water dispersion composition of the present invention is characterized in that it comprises, after the second step, a third step (aging) of leaving the composition to stand for at least 1 hour. According to this method for producing an oil-in-water dispersion composition, the thickener dispersed within the oil droplets increases the viscosity around the oil droplets over time, thereby improving dispersion and emulsion stability.

[0010] Furthermore, one embodiment of the method for producing an oil-in-water dispersion composition of the present invention is characterized in that the average particle radius of the oily inner layer is 0.1 mm or more. This method for producing an oil-in-water dispersion composition has the effect of making the oil droplets in the outer aqueous layer easily visible, resulting in excellent aesthetics.

[0011] Furthermore, one embodiment of the method for producing an oil-in-water dispersion composition of the present invention is characterized in that the viscosity of the aqueous outer layer is 100 to 6000 mPa·s and the viscosity of the oily inner layer is 10 to 5000 mPa·s. This method for producing an oil-in-water dispersion composition has the effect of providing superior dispersion and emulsion stability due to the relationship between the viscosity of the aqueous outer layer and the viscosity of the oily inner layer.

[0012] Furthermore, one embodiment of the method for producing an oil-in-water dispersion composition of the present invention is characterized in that the specific gravity of the aqueous outer layer is 0.900 to 1.200, the specific gravity of the oily inner layer is in the range of 0.900 to 1.200, and the ratio of the specific gravity of the oily inner layer to the aqueous outer layer (specific gravity of the oily inner layer / specific gravity of the aqueous outer layer) is 0.95 to 1.05. This method for producing an oil-in-water dispersion composition has the effect of making the composition less susceptible to separation due to the relationship between the specific gravity of the outer aqueous layer and the inner oily layer, and thus providing superior dispersion and emulsion stability.

[0013] Furthermore, in one embodiment of the method for producing an oil-in-water dispersion composition of the present invention, the aqueous outer layer contains 0 to 50 mass% of component (A) water and component (B) ethanol, the thickener contains component (C) at least one thickening polymer that is soluble in water and sparingly soluble in ethanol and oil, and the oily inner layer contains component (D) a silicone oil that is liquid at room temperature and has a viscosity at 25°C of 10 mPa s or more. According to this method for producing an oil-in-water dispersion composition, by specifying these conditions, it is possible to maintain a large particle size of the oily inner layer, and therefore to produce an oil-in-water dispersion composition that is excellent in aesthetics and has better dispersion and emulsion stability. [Effects of the Invention]

[0014] The present invention has the effect of providing an oil-in-water emulsion composition that is easy to mix, has excellent dispersion and emulsion stability, and is likely to maintain the state of an oily inner layer in the form of oil droplets in an aqueous outer layer. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating one embodiment of an oil-in-water dispersion composition of the present invention. [Figure 2] FIG. 1 is a diagram showing a conventional mixture of oily granular material and aqueous liquid material. DETAILED DESCRIPTION OF THE INVENTION

[0016] The oil-in-water dispersion composition of the present invention and the method for producing the oil-in-water dispersion composition will be described in detail below. The oil-in-water dispersion composition produced by the production method of the present invention is an oil-in-water composition, which contains an oily inner layer, an aqueous outer layer, and a thickener, and in which the oily inner layer is stably maintained in the form of oil droplets within the aqueous outer layer. Furthermore, the oil-in-water dispersion composition of the present invention does not contain solid powder, solid oil, or oily gelling agent. The oil-in-water dispersion composition produced by the production method of the present invention also includes a typical oil-in-water emulsion composition. The oily inner layer also includes a dispersion composition in which water droplets are dispersed in the oily inner layer. In other words, it also includes a composition called a water-in-oil-in-water type. In addition, each component used in the oil-in-water dispersion composition of the present invention and the oil-in-water dispersion composition produced by the production method will be described in detail. Unless otherwise specified in this specification, the mass % of each component is based on the mass of the entire oil-in-water dispersion composition of the present invention. Furthermore, the outer aqueous layer in the oil-in-water dispersion composition means a state in which a thickener is dissolved.

[0017] <Oil-in-water dispersion composition> The oil-in-water dispersion composition of the present invention is a multilayer dispersion composition characterized by comprising two or more layers with different properties. Here, "different properties" refers to the properties of not easily mixing with each other by themselves, such as the relationship between water and oil, water and powder, or oil and powder. Furthermore, a multilayer dispersion refers to a state in which two or more dispersions with different properties exist independently in each layer. Here, the state in which two or more dispersions with different properties exist independently in each layer of the present invention also includes ordinary emulsion compositions and emulsions. Furthermore, this also includes compositions that do not necessarily exist in an emulsified state upon standing, as long as they change into an emulsion during use. In this specification, "emulsion" refers to a state in which the emulsion particle size is 1 μm or more to 10 μm or less. Furthermore, emulsion-like compositions may coexist in other layers. For example, a water-in-oil emulsion-like dispersoid may exist independently suspended in an aqueous dispersion medium.

[0018] As shown in Figure 1, the oil-in-water dispersion composition of the present invention is a multilayer dispersion consisting of two or more layers with different properties, wherein at least one of the two or more layers is an outer aqueous layer composed of a water-soluble composition, and at least one layer is an inner oily layer composed of an oil-soluble composition, and the oil-in-water dispersion composition is characterized in that all or part of the inner oily layer composed of the oil-soluble composition is present in particulate form. Examples of the composition of the present invention include a composition in which one oil-soluble composition is present independently in particulate form in one or more layers composed of one or more water-soluble compositions, or a composition in which two or more oil-soluble compositions are present independently in particulate form in one or more layers composed of one or more water-soluble compositions. By combining an outer aqueous layer and an inner oily layer having the characteristics described in detail below, the oil-in-water dispersion composition of the present invention can, even without the addition of a surfactant, allow the oily granules to stably and independently float without separation from the aqueous layer, as seen in the case of a conventional oily granule mixed with an aqueous liquid as shown in Figure 2.

[0019] Furthermore, the oil-in-water dispersion composition of the present invention preferably has a transparent appearance. A transparent appearance means, for example, that the lightness L value of the oil-in-water dispersion composition measured using a color meter is 50 or more. Preferably, the L value of the oil-in-water dispersion composition is 70 or more, and more preferably, the L value of the oil-in-water dispersion composition is 90 or more. The lightness can be measured using any color meter. For example, the ColorMeterZE6000 manufactured by Nippon Denshoku Industries Co., Ltd. is one such example.

[0020] The oil-in-water dispersion composition of the present invention is an oil-in-water dispersion composition comprising multiple independently existing layers, the multiple layers comprising an aqueous outer layer having a viscosity of 100 to 6000 mPa·s and an oily inner layer having a viscosity of 10 to 5000 mPa·s. Preferably, the oil-in-water dispersion composition of the present invention comprises an aqueous outer layer having a viscosity of 1500 to 3500 mPa·s and an oily inner layer having a viscosity of 100 to 1500 mPa·s. Having the oily inner layer and the aqueous outer layer with viscosities within the above ranges allows for a beautiful appearance. From the perspective of a particularly beautiful appearance, it is preferable that the viscosity of the aqueous outer layer is 1500 to 3500 mPa·s and that of the oily inner layer is 100 to 1500 mPa·s. In the present invention, a beautiful appearance refers to a unique appearance in which the outer and inner layers are transparent, the particles comprising the oily inner layer are large, and the oily inner layer is independently suspended within the aqueous outer layer. The viscosity of the aqueous outer layer and the oily inner layer described above has the effect of making it easier to maintain the granular state of the oily outer layer, and the relationship between the viscosities of the aqueous outer layer and the oily inner layer has the effect of providing better dispersion and emulsion stability.

[0021] In this specification, the term "viscosity" refers to the viscosity at 25°C, and is a value measured using a viscometer (DV-1 viscometer manufactured by Brookfield).

[0022] The oil-in-water dispersion composition of the present invention preferably comprises an oily inner layer made of particles with an average particle radius of 0.1 mm or more suspended in an aqueous outer layer. In the present invention, the particle radius of the oily layer is the geometric particle radius measured on a two-dimensional screen using a microscope. In this specification, the average particle radius refers to the radius of the particle size histogram at which the highest frequency is visually recognized, i.e., the modal radius. Here, a histogram is a type of statistical graph with frequency on the vertical axis and class on the horizontal axis, and is a graphical diagram used primarily in statistics, mathematics, image processing, etc. to visually recognize the distribution of data. An average particle radius of 0.1 mm or more is preferable from the perspective of aesthetic appearance. An average particle radius of 0.1 mm or more has the effect of making oil droplets in the aqueous outer layer more visible, resulting in excellent aesthetics.

[0023] The oil-in-water dispersion composition of the present invention preferably has a mass ratio of the outer layer to the inner layer of 99.9:0.01 to 50:50. When the ratio of the inner layer to the outer layer is 50 or less, the dispersion stability of the particles in the oil-in-water dispersion composition is good, and independent spherical layers can be formed. Furthermore, when the ratio of the inner layer to the outer layer is 0.01 or more, the effects of the oil formulation, such as treatment effect, damage care effect, moisturizing effect, and gloss-imparting effect, can be favorably exhibited, which is preferable.

[0024] The oil-in-water dispersion composition of the present invention has an L value, which indicates the brightness of the outer layer, of 50 or more. Preferably, the L value of the outer layer is 70 or more, and more preferably, the L value of the outer layer is 90 or more. The brightness can be measured using any color meter. For example, the ColorMeter ZE6000 manufactured by Nippon Denshoku Industries Co., Ltd. is one example. When the brightness L value is 50 or more, the composition has transparency in appearance, and it is possible to provide an oil-in-water dispersion composition with excellent appearance quality.

[0025] The oil-in-water dispersion composition of the present invention is a composition having an outer layer containing a polymer whose lightness L value of a 0.5% by mass aqueous solution is at least 35. Furthermore, the polymer is preferably a (C) thickening polymer that is water-soluble and sparingly soluble in ethanol and oil.

[0026] In the oil-in-water dispersion composition of the present invention, it is preferred that the specific gravity of the outer aqueous layer and the inner oily layer each be in the range of 0.900 to 1.200, or that the density of the outer aqueous layer and the inner oily layer each be in the range of 0.900 to 1.200.

[0027] Furthermore, the ratio of the specific gravity of the aqueous outer layer to the specific gravity of the oily outer layer (specific gravity of the oily inner layer / specific gravity of the aqueous outer layer) is preferably 0.95 or more and 1.05 or less. This has the effect of making it easier for the granular oily inner layer to remain suspended throughout the entire aqueous outer layer for a long period of time. In addition, due to the relationship between the specific gravity of the aqueous outer layer and the oily inner layer, separation is less likely to occur, resulting in better dispersion and emulsion stability. The ratio of the specific gravity of the outer aqueous layer to the specific gravity of the outer oily layer (specific gravity of the inner oily layer / specific gravity of the outer aqueous layer) has a lower limit of more preferably 0.97 or more, and most preferably 0.98 or more, and an upper limit of more preferably 1.03 or less, and most preferably 1.02 or less.

[0028] Furthermore, in the oil-in-water dispersion composition of the present invention, the outer layer contains (A) water and one or more (C) thickening polymers that are water-soluble but poorly soluble in ethanol and oil. The outer layer of the present invention may also contain (B) ethanol. When the oil-in-water dispersion composition of the present invention contains component (B), the ethanol may be ethanol or denatured ethanol not specified by the government, and such ethanol may be obtained by either a fermentation method or a synthetic method.

[0029] When the component (B) of the present invention is contained, the ethanol content is 50.0% by mass or less, preferably 35.0% by mass or less. The lower limit of the content of the component (B) is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more. When the content of the component (B) is 50.0% by mass or less, the thickening polymer (C) swells sufficiently, which is desirable because it serves to adjust the viscosity, specific gravity, and density, and also maintains the qualities of the composition, such as feel, stability, and transparency. Here, the ethanol content is based on the total mass of the oil-in-water dispersion composition of the present invention.

[0030] The thickening polymer, component (C) of the present invention, is a polymer that exhibits thickening properties in an aqueous solution. It may be a natural polymer derived from a plant, animal, or microorganism, a natural polymer derivative, a synthetic polymer, or an inorganic thickener. Examples of the thickening polymer include, but are not limited to, plant-based polymers such as alginic acid, carrageenan, agar, furcella, guar gum, quince seed, konjac mannan, tamarind gum, tara gum, starch, dextrin, locust bean gum, gum arabic, ghatti gum, karaya gum, tragacanth gum, arabinogalactan, pectin, quince, wheat protein, and soy protein; animal-based polymers such as albumin, casein, gelatin, chitosan, and hyaluronic acid; and curdlan, xanthan gum, gellan gum, cyclodextrin, dextrin, protease, and the like. Microbial-based materials such as lulan and hyaluronic acid; cellulose-based materials such as microcrystalline cellulose, methylcellulose, ethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, cationic cellulose, and stearoxyhydroxypropylmethylcellulose; starch-based materials such as starch phosphate esters and sodium starch glycolate; guar gum-based materials such as cationic guar gum, carboxymethyl-hydroxypropylated guar gum, and hydroxypropylated guar gum;Synthetic polymers with a basic main chain such as acrylic group, methacrylic group, vinyl group, ether, maleic anhydride, polypiperidine, polyalkylene polyamine, polyethyleneimine, polyamide, polycation, for example, carboxyvinyl polymer, polyacrylic acid amide, sodium polyacrylate, polyethyleneimine, highly polymerized polyethylene glycol, starch-sodium acrylate graft polymer, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylate, polyacrylate-1, polyacrylate crosspolymer-11, vinyl acetate-vinylpyrrolidone copolymer, (ammonium acryloyldimethyltaurate / carboxyethylammonium acrylate) crosspolymer, (ammonium acryloyldimethyltaurate / beheneth-25 methacrylate) crosspolymer copolymers, alkyl acrylate / alkyl methacrylate / polyoxyethylene stearyl ether methacrylate copolymer emulsion, (sodium acrylate / sodium acryloyldimethyltaurate) copolymer, (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer, (acrylamide / ammonium acrylate) copolymer, (acrylates / C10-30 alkyl acrylate) crosspolymer, (acrylates / steareth-20 itaconate) copolymer, (VP / hexadecene) copolymer, (ammonium acryloyldimethyltaurate / VP) copolymer, (VP / methacrylamide / vinylimidazole) copolymer, etc., (acrylic acid / vinylpyrrolidone) copolymer, (methyl vinyl ether / maleic acid) crosspolymer;Other examples include inorganic thickeners such as hectorite, dimethyl distearyl ammonium hectorite, bentonite, and saponite. From the viewpoints of beautiful appearance, stability, and good feel, it is preferable to use a polymer that is particularly soluble in water and sparingly soluble in ethanol and oil, and more preferably a polymer that is soluble in water, sparingly soluble in ethanol and oil, and is nonionic. "Soluble in water" means that when prepared as a 0.5% by mass aqueous solution (25°C), the polymer is completely dissolved, leaving no solid matter. "Sparely soluble in ethanol and oil" means that when prepared as a 0.5% by mass ethanol solution or in any oil (25°C), solid matter remains. In the present invention, the thickener in the oil-based solution is a thickening polymer that is soluble in water and poorly soluble in ethanol and oil. By this, the thickener at the interface between the outer aqueous layer and the oil droplets further increases the viscosity around the oil droplets, making it easier to maintain the state of the oil droplets in the outer aqueous layer, and providing better dispersion and emulsion stability.

[0031] The thickening polymer (C) of the present invention may be used alone or in combination of two or more. The content of the thickening polymer (C) is in the range of 0.01 to 30% by mass, preferably 0.05 to 10.0% by mass, based on the total mass of the oil-in-water dispersion composition of the present invention. A content of 0.05% by mass or more is effective in maintaining the oily inner layer in a particulate state and providing excellent dispersion stability, while a content of 30% by mass or less is preferable because it prevents a significant increase in the viscosity of the outer layer and allows the fluidity of the oil-in-water dispersion composition to be maintained.

[0032] The component (C) of the present invention may be neutralized with salts or acids as necessary before use, and may be used alone or in combination of two or more.

[0033] The oil-in-water dispersion composition of the present invention contains the above-mentioned components (A) to (C) in the aqueous outer layer and an oily inner layer (D) that is liquid at room temperature. In the present invention, component (D) can be a combination of a silicone oil that is liquid at room temperature as (D1) and an oily agent that is liquid at room temperature other than (D1) as (D2), as described in detail below. In this specification, "room temperature" refers to 25°C.

[0034] The liquid oil of component (D) of the present invention is an oil that is liquid at room temperature. Component (D1) may contain a silicone oil that is liquid at room temperature and has a viscosity of 10 mPa s or greater at 25°C. The silicone oil is not particularly limited, and examples thereof include various silicones such as volatile dimethicone, highly polymerized dimethicone, silicone blends, various modified silicones, and silicone resins, such as dimethicone, cyclomethicone, cyclopentasiloxane, phenyl trimethicone, diphenylsiloxyphenyl trimethicone, polysilicone-13, dimethiconol, trimethylpentaphenyl trisiloxane, amodimethicone, (divinyl dimethicone / dimethicone) copolymer, cyclohexasiloxane, caprylyl methicone, cetyl dimethicone, bis(hydroxyethoxypropyl)dimethicone, (diphenylmethylsiloxyphenylmethicone / phenylsilsesquioxane) crosspolymer, (dimethicone / vinyl dimethicone) crosspolymer, and dimethicone crosspolymer. Among these, dimethicone is preferably used because it provides a particularly good feel.

[0035] The component (D) of the present invention may further contain other liquid oils (excluding the silicone oil (D1) above) as component (D2). While not particularly limited, at least one of oils and fats such as ester oils, hydrocarbon oils, natural oils, higher alcohols, and higher fatty acids may be contained. For example, isodecyl neopentanoate, ethylhexyl isononanoate, isopropyl myristate, hexyl laurate, diisobutyl adipate, isononyl isononanoate, isopropyl palmitate, isodecyl isononanoate, ethyl isostearate, isopropyl isostearate, hexyldecyl ethylhexanoate, diethylhexyl succinate, isotridecyl isononanoate, neopentyl glycol diethylhexanoate, isobutyl isostearate, cetyl ethylhexanoate, ethylhexyl palmit ... Isostearyl Pentanoate, Neopentyl Glycol Dicaprate, Isocetyl Myristate, Neopentyl Glycol Diisononanoate, Caprylic / Capric Triglyceride, Octyldodecyl Myristate, Isocetyl Stearate, Triethylhexanoin, Hexyldecyl Isostearate, Isostearyl Isostearate, Tricyclodecane Methyl Isononanoate, Trimethylolpropane Triethylhexanoate, Ethylhexyl Hydroxystearate, Octyldodecyl Stearoyloxystearate , diisopropyl dilinoleate, triisostearin, trimethylolpropane triisostearate, pentaerythrityl tetraisostearate, polyglyceryl-2 triisostearate, polyglyceryl-2 diisostearate, sodium isostearoyl lactylate, dipentaerythrityl hexaisononanoate, polyglyceryl-2 isostearate, diisostearyl malate, polyglyceryl-3 diisostearate and other ester oils; light isoparaffin (isododecane), light liquid isoparaffin, α-olefin oligomer, synthetic squalane, vegetable squalane, polybutene, hydrogenated poly Examples of suitable oils include liquid hydrocarbons such as isobutylene and liquid paraffin; unsaturated fatty acids and branched fatty acids such as oleic acid, isostearic acid, undecylenic acid, linoleic acid, and linolenic acid; liquid higher alcohols such as oleyl alcohol, jojoba alcohol, isostearyl alcohol, octyldodecanol, hexyldecanol, benzyl alcohol, and lauryl alcohol; and natural oils such as rice germ oil, rice bran oil, apricot oil, castor oil, camellia oil, rosehip oil, grapeseed oil, olive oil, jojoba oil, sesame oil, perilla oil, southern arugula oil, walnut oil, avocado oil, coconut oil, sunflower oil, and linseed oil. Among these, liquid ester oils and hydrocarbons are particularly preferred.

[0036] The liquid oil of component (D) of the present invention may be a single component (D1) or a combination of two or more components, or may be a single component (D1) or a combination of components (D1) and (D2). The content of the liquid oil of component (D) is preferably in the range of 0.1 to 50% by mass, more preferably 1 to 30% by mass, based on the total mass of the oil-in-water dispersion composition of the present invention. A content of 50% by mass or less is preferred because the composition has good stability and can form independent spherical layers.

[0037] The viscosity of component (D) of the present invention is preferably 10 mPa·s or more, more preferably 50 mPa·s or more, and even more preferably 100 mPa·s or more.

[0038] The oil-in-water dispersion composition of the present invention may further contain an aqueous rheology modifier as component (E). The aqueous rheology modifier is not particularly limited, but is one that increases the viscosity of an aqueous solution when added to the aqueous solution (excluding component (C)). Specific examples thereof include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polyoxyethylene polyoxypropylene glycol, glycerin, diglycerin, polyglycerin, isoprene glycol, and 1,3-butylene glycol; polyols such as polyoxyethylene glycerin, polyoxypropylene glyceryl ether, polyoxyethylene polyoxypropylene glyceryl ether, polyoxybutylene polyoxyethylene polyoxypropylene glyceryl ether, polyoxyethylene polyoxypropylene trimethylolpropane, polyoxypropylene diglyceryl ether, and polyoxyethylene polyoxypropylene alkyl ether; sugar alcohols such as sorbitol, mannitol, xylitol, maltitol, and erythritol; sugars such as glucose, sucrose, lactose, maltose, trehalose, and glycosyltrehalose; water-soluble esters such as bisethoxydiglycol succinate, bisethoxydiglycol cyclohexane-1,4-dicarboxylate, and polyglyceryl-10 (eicosandioate / tetradecanedioate); water-soluble silicone compounds such as polyether-modified silicone; amino acids, salts, and acids such as serine, valine, alanine, glycine, leucine, glutamic acid, histidine, aspartic acid, threonine, isoleucine, phenylalanine, proline, arginine, tyrosine, phenylalanine, and trimethylglycine.

[0039] The aqueous rheology control agent (component (E)) of the present invention may be used alone or in combination of two or more. The content is preferably 0.01 to 30% by mass, more preferably 0.1 to 10% by mass, based on the total mass of the oil-in-water dispersion composition. If the content is 0.01% by mass or more, the feeling in use, such as smoothness, and the viscosity and specific gravity can be adjusted satisfactorily, while if the content is 30% by mass or less, problems with the feel, such as stickiness, do not occur, and the boundary between layers with different properties does not collapse, maintaining quality, which is preferable.

[0040] Furthermore, the component (F) of the present invention may contain the following ingredients. Examples include, but are not limited to, fragrances, essential oils, fruit juices and plant extracts, extracts, natural pigments with a general structure such as flavonoids, carotenoids, quinones, and porphyrins, and prophenol-containing extracts such as caramel and butterfly pea extract.

[0041] The component (F) of the present invention may be used alone or in combination of two or more types, and may be contained in the outer layer, the inner layer, or both.

[0042] The composition of the present invention may be used as any of a skin care composition, a body care composition, and a hair care composition, and may be in either a rinse-in or rinse-off form.

[0043] Furthermore, as needed, other additional components typically used in cosmetics and the like can be blended within limits that do not impair the effects of the present invention. These additional components include, for example, antibacterial agents, ultraviolet absorbers, antioxidants, physiologically active substances, whitening agents, vitamins and their derivatives, anti-inflammatory agents, anti-inflammatory agents, hair growth agents, blood circulation promoters, stimulants, hormones, anti-wrinkle agents, anti-aging agents, firming agents, cooling agents, warming agents, wound healing promoters, irritation alleviators, analgesics, cell activators, antipruritics, exfoliants, keratolytic agents, antiperspirants, cooling agents, astringents, and the like, as well as chelating agents, electrolytes, alkalis, acids, surfactants, setting resins, solid powders, and the like.

[0044] <Method of producing oil-in-water dispersion composition> The method for producing the oil-in-water dispersion composition of the present invention comprises a first step of mixing an oily inner layer composition with a thickener, a second step of mixing the oily inner layer composition mixed in the first step with an aqueous outer layer, a third step (aging) of leaving the mixture to stand for at least 1 hour after the second step, and a fourth step of filling the mixture into a container.

[0045] The first step is to mix the oily inner layer with a thickener. In this step, the thickener does not swell with water because the mixture is substantially free of water. In this step, an oily inner layer composition is produced in which the thickener is dispersed in the oily inner layer.

[0046] In the second step, the oily inner layer composition produced in the first step is mixed with the aqueous outer layer. This step converts the oily inner layer into oil droplets, producing an oil-in-water dispersion composition. It is believed that the thickener at the interface between the aqueous outer layer and the oil droplets swells with the water in the aqueous outer layer, thereby increasing the viscosity around the oil droplets. This increase in viscosity is believed to improve the dispersion and emulsion stability of the oil-in-water dispersion composition.

[0047] In the third step, mixing of the oil-in-water dispersion composition is stopped, and the oil-in-water dispersion composition is allowed to stand for at least 1 hour. This aging step is thought to cause the remaining thickener in the oil droplets to swell at the interface between the outer aqueous layer and the oil droplets over time, further increasing the viscosity around the oil droplets. This increase in viscosity is thought to further improve the dispersion and emulsion stability of the oil-in-water dispersion composition. The time for leaving the mixture to stand is at least 1 hour, preferably 3 hours or more, and more preferably 5 hours or more.

[0048] In the fourth step, after the standing time has elapsed, the oil-in-water dispersion composition is filled into containers and distributed on the market.

[0049] In a production method including steps 1 and 2, the thickener increases the viscosity around the oil droplets at the interface between the aqueous outer layer and the oil droplets, which makes it easier to maintain the state of the oil droplets in the aqueous outer layer and results in excellent dispersion and emulsion stability. Furthermore, this method suppresses the generation of stepchildren and makes mixing easier than when a thickener is mixed into the aqueous outer layer and then the oily inner layer is mixed with the aqueous outer layer containing the thickener.

[0050] Furthermore, by carrying out the third step after the first and second steps, the thickener dispersed within the oil droplets increases the viscosity around the oil droplets over time, thereby improving dispersion and emulsion stability.

[0051] The production method of the present invention may also include steps 1, 2, and 4. That is, in step 2, the aqueous thickener may be mixed until it is completely swelled, and step 3 may not be performed. Even in this case, the effects of dispersion and emulsion stability can be obtained, and the generation of stepchildren can be suppressed.

[0052] The mixing method in the method for producing the oil-in-water dispersion composition of the present invention is not particularly limited, and includes, for example, using a known device such as a propeller mixer, paddle mixer, anchor mixer, gate mixer, planetary mixer, or static mixer, or mixing by shaking the mixture in a container. When using such a known device, the rotation speed of the stirring blade is not particularly limited. The average particle radius of the oil droplets in the oily inner layer can be adjusted by adjusting the stirring conditions in the second step. Furthermore, when the average particle radius of the oil droplets in the oily inner layer is 0.1 mm or more and 8.0 mm or less, the oil droplets in the aqueous outer layer are easily visible, which has the effect of providing excellent aesthetics and excellent storage stability. From the viewpoint of excellent aesthetics, the lower limit of the average particle radius of the oil droplets in the oily inner layer is preferably 0.1 mm or more, more preferably 1.0 mm or more, even more preferably 4.0 mm or more, and particularly preferably 8.0 mm or more. From the viewpoint of excellent storage stability, the upper limit of the average particle radius of the oil droplets in the oily inner layer is preferably 8.0 mm or less, more preferably 4.0 mm or less, even more preferably 1.0 mm or less, and particularly preferably 0.1 mm or less. [Example]

[0053] The present invention will be described in detail below with reference to examples, but the technical scope of the present invention is not limited to these examples. Regarding the oil-in-water dispersion compositions described in the examples and comparative examples, test methods for (1) particle size, (2) transparency, (3) thickener mixability, (4) storage stability, and (5) oil formulation effects are shown below.

[0054] (1) Particle size Each sample was prepared in a room maintained at 25°C, and the radius of the oily particles was measured and evaluated using a microscope. A histogram graph was then created, and the particle shape was evaluated using the radius value showing the highest frequency.

[0055] <Particle morphology evaluation criteria> "Large": The average particle radius indicated by the highest frequency in the size histogram is greater than 8.0 mm. "Medium": The average particle radius indicated by the highest frequency on the size histogram is 0.1 mm or more and 8.0 mm or less. "Small": The average particle radius indicated by the highest frequency in the size histogram is less than 0.1 mm "-": Not enough oil droplets. "Partially large": The oil is not granular as a whole. The average particle radius is partially "large" (the oil layer around the stirring blades of the stirring device becomes granular). "Partially medium": Not granular as a whole. Partially has a "medium" average particle radius. "Partially small": Not granular as a whole. Partially has a "small" average particle radius.

[0056] (2) Transparency (Transparency of oil-in-water dispersion composition) Each sample was visually evaluated by 20 subjects in a room maintained at 25° C. The evaluation criteria were as follows:

[0057] <Evaluation criteria for transparency of oil-in-water dispersion compositions> "Transparent": 10 or more test subjects judged the product to be highly transparent "Semi-transparent": 10 or more test subjects judged the transparency to be low "Muddy": Fewer than 10 subjects judged it to be lacking transparency

[0058] (3) Mixability of thickeners The ease of mixing when mixing the thickener into either the oil layer or the water layer (generation of step-children) and the ease of mixing when mixing the oil layer and the water layer (generation of step-children) were evaluated. "◎": No stepchildren are observed and mixing is easy. "X": Stepchildren occur and mixing takes time.

[0059] (4) Storage stability After stirring the oil-in-water emulsion composition, each sample was left to stand in a room maintained at 25°C, and 20 subjects evaluated the state of the oil droplets in the oil-in-water dispersion composition after stirring and after one month had passed. "◎": Almost no change in oil droplets or uneven separation was observed even after one month had passed. "Good": After one month, slight changes in the oil droplets and uneven separation were observed. "△": After one month, changes in oil droplets and uneven separation were often observed. "X": Within one month, obvious changes in the oil droplets and significant uneven separation were observed. "-": No oil droplets formed and not subject to evaluation. Or, the water layer and oil layer immediately separated.

[0060] (5) Effects of oil preparations Twenty subjects took the oil-in-water emulsion composition in their hands in a room maintained at 25°C, spread it on their arms, and evaluated the degree to which the oily component was felt (oily feeling). "◎" The oily feel is strong. "○" Light oily feeling "X": There is only a slight oily feeling.

[0061] Examples 1 to 12 and Comparative Examples 1 to 4 As shown in Tables 1 to 3, oil-in-water dispersion compositions were produced by the method for producing an oil-in-water dispersion composition of the present invention (Steps 1, 2, and 3) using a known stirring device. The oil-in-water dispersion compositions described in the Examples and Comparative Examples were evaluated for (1) particle size, (2) transparency, (3) mixability with thickeners, (4) storage stability, and (5) effects of oil formulations, and the results are also shown in Tables 1 to 4. The mixing in the second step was performed so that the average particle radius of the oil droplets in the oily inner layer was 0.1 mm or more. The standing time in the third step was set to 1 hour. In Examples 1 to 12, the viscosity of the aqueous outer layer was adjusted to 100 to 6000 mPa·s, and the viscosity of the oily inner layer was adjusted to 10 to 5000 mPa·s. Furthermore, the specific gravity of the aqueous outer layer is 0.900 to 1.200, the specific gravity of the oily inner layer is in the range of 0.900 to 1.200, and the ratio of the oily inner layer to the aqueous outer layer (specific gravity of the oily inner layer / specific gravity of the aqueous outer layer) is adjusted to 0.95 to 1.05. In the examples, the oil-in-water dispersion composition does not contain a surfactant.

[0062] [Table 1]

[0063] As shown in Table 1, mixing the thickener into the oily inner layer and then mixing the oily inner layer with the thickener mixed in with the aqueous outer layer is a manufacturing method that does not produce any stepchildren and is easier to mix.

[0064] [Table 2]

[0065] A comparison of Example 1 and Examples 4 to 8 shows that the mixability of the thickeners is good even when different types of thickeners are used in Component C. It is also clear that the use of ethanol in Component B results in good transparency.

[0066] [Table 3]

[0067] Comparing Example 1 with Examples 9 to 12, it is clear that the thickeners are well mixed even though the oil agent of component (D) is different. [Industrial Applicability]

[0068] The production method of the present invention can be used in a production method of an oil-in-water dispersion composition, which involves mixing a thickener with an oily component such as an oily inner layer, and then stirring an aqueous component such as an aqueous outer layer and the oily component with the thickener mixed therein. The production method of the present invention can also be used for an oil-in-water dispersion composition in which the average particle radius of the oil droplets in the oily inner layer is less than 0.1 mm. The oil-in-water dispersion composition produced by the production method of the present invention can also be used as a cosmetic product, such as a skin care composition, a body care composition, or a hair care composition. The oil-in-water dispersion composition produced by the production method of the present invention can also be used in the food industry. [Explanation of symbols]

[0069] 1 Transparent multilayer dispersion composition 2. Oily inner layer 3 Aqueous outer layer 10. A mixture of conventional oil-based granular material and aqueous liquid material (surfactant-free) 20 Oily particulate matter 30 Water-based liquids

Claims

1. A first step of mixing an oily inner layer with a thickener; a second step of mixing the oily inner layer composition mixed in the first step with an aqueous outer layer; A method for producing an oil-in-water dispersion composition comprising: the viscosity of the aqueous outer layer is 100 to 6000 mPa s, and the viscosity of the oily inner layer is 10 to 5000 mPa s; the specific gravity of the aqueous outer layer is in the range of 0.900 to 1.200, and the specific gravity of the oily inner layer is in the range of 0.900 to 1.200; the ratio of the oily inner layer to the aqueous outer layer (specific gravity of the oily inner layer / specific gravity of the aqueous outer layer) is 0.95 to 1.05; The oil-in-water dispersion composition comprises an oily inner layer made of particles having an average particle radius of 0.1 mm or more suspended in an aqueous outer layer.

2. 2. The method for producing an oil-in-water dispersion composition according to claim 1, wherein the thickener in the oil-based dispersion is a thickening polymer that is soluble in water and sparingly soluble in ethanol and oil.

3. 3. The method for producing an oil-in-water dispersion composition according to claim 1, wherein the aqueous outer layer contains the following components (A) and (B), and the oily inner layer contains the following components (C) and (D): (A) Water (B) 0 to 50% by mass of ethanol (C) at least one thickening polymer that is soluble in water and sparingly soluble in ethanol and oil; (D) Silicone oil that is liquid at room temperature and has a viscosity of 10 mPa·s or more at 25°C

4. 2. The method for producing an oil-in-water dispersion composition according to claim 1, further comprising a third step of leaving the composition to stand for at least one hour after the second step.

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