Water-in-oil emulsion composition

Abstract

The purpose of the present invention is to provide a water-in-oil emulsion composition having improved dispersibility of polysaccharide-based particles. This water-in-oil emulsion composition is obtained by a water-in-oil emulsion composition production method comprising: a step A for preparing a base-use water-in-oil emulsion composition from an oil-phase composition and a water-phase composition; and a step B for mixing the base-use water-in-oil emulsion composition with particles mainly composed of a polysaccharide-based polymer selected from the group consisting of polysaccharides and polysaccharide esters. The water-in-oil emulsion composition excels in dispersibility with respect to particles containing a polysaccharide-based polymer as a main component.

Description

Water-in-oil emulsion composition

[0001] The present invention relates to a water-in-oil emulsion composition in which the dispersibility of polysaccharide particles is improved.

[0002] A water-in-oil emulsion composition is an emulsion composition in which the continuous phase is an oil phase and the dispersed phase is an aqueous phase. A water-in-oil emulsion composition is produced by emulsifying an oil phase composition in which an emulsifier has been dissolved by gradually adding an aqueous phase composition to the oil phase composition while applying shear by stirring with a disper mixer or homomixer. During emulsification, the oil phase composition and the aqueous phase composition are heated to 70 to 80°C to effectively obtain an emulsion by reducing the interfacial tension.

[0003] Water-in-oil emulsion compositions are widely used as one type of cosmetic formulation, and those used as cosmetics often contain solid particles as a texture improver. Water-in-oil emulsion compositions containing solid particles are produced by pre-dispersing the solid particles in an oil phase composition and then emulsifying by adding an aqueous phase (Patent Documents 1 and 2). The reason for pre-dispersing the solid particles in the oil phase composition is to achieve the intended effect of the texture improver by forming a uniform coating film containing dispersed particles after application of the water-in-oil emulsion composition. Furthermore, when dispersing the solid particles in the oil phase composition, the oil phase composition is heated to approximately 70 to 80°C to facilitate mechanical crushing of the solid particles into primary particles and dispersion in the oil phase composition, as well as to facilitate dissolution of the oil-soluble components dissolved at the same time.

[0004] Various types of solid particles are known to be incorporated into cosmetics depending on the purpose (coloring, moisture absorption, UV protection, texture improvement, etc.), and specific examples include inorganic pigments (titanium oxide, yellow iron oxide, black iron oxide, red iron oxide, etc.), inorganic powders (mica, talc, silica, mica, etc.), plastic particles (nylon, acrylic resin, etc.), polysaccharide particles (cellulose, cellulose ester, etc.), etc.

[0005] JP 2013-213041 A JP 2018-188411 A

[0006] Due to recent concerns about marine pollution caused by plastic particles, there has been a growing trend to restrict the use of plastic particles in cosmetic feel modifiers and to switch to particles made from materials with less environmental impact. While inorganic particles or polysaccharide particles can be used as particles made from materials with less environmental impact, inorganic particles generally do not provide sufficient effectiveness as feel modifiers due to their inherent hardness or squeaky sound. For this reason, polysaccharide-based particles have no choice but to be used as environmentally friendly feel modifiers.

[0007] Most solid particles used in cosmetics can be incorporated into water-in-oil emulsion compositions with good dispersibility using the above-mentioned production method, but polysaccharide particles have the problem of aggregation occurring immediately after preparation of the water-in-oil emulsion composition.

[0008] Therefore, an object of the present disclosure is to provide a water-in-oil emulsion composition in which the dispersibility of polysaccharide particles is improved.

[0009] Without being bound by theory, it is believed that aggregation occurs when polysaccharide particles are used due to the following mechanism. Specifically, when an aqueous phase composition is added to an oil phase composition, the water in the aqueous phase, which is finely chopped by shear during stirring, comes into contact with the polysaccharide particles in the oil phase composition, forming hydrogen bonds between the hydroxyl groups of the polysaccharide particles and the water, and then the hydrogen-bonded water forms another hydrogen bond with the hydroxyl groups of another polysaccharide particle. It is believed that this continuous occurrence causes multiple polysaccharide particles to string together like balls, with water acting as an adhesive, to form aggregates. Therefore, the present inventors prepared a water-in-oil emulsion composition (hereinafter referred to as a water-in-oil base emulsion composition) that did not contain polysaccharide particles, temporarily encapsulated the aqueous phase in an emulsion membrane, and then blended the polysaccharide particles. It has been found that this production method allows polysaccharide particles to be dispersed in the oil phase, which is the continuous phase of the water-in-oil base emulsion composition, and that aggregation of the resulting water-in-oil emulsion composition is significantly suppressed, presumably by the emulsion membrane preventing contact between the hydroxyl groups of the polysaccharide particles and the water in the aqueous phase. The present disclosure has been completed based on this finding.

[0010] That is, the present disclosure provides the following aspects of the invention. Item 1. A water-in-oil emulsion composition comprising, in an oil phase, particles whose main component is a polysaccharide polymer selected from the group consisting of polysaccharides and polysaccharide esters, wherein the dispersibility of the particles is 130 μm or less as measured using a grind gauge. Item 2. The water-in-oil emulsion composition according to Item 1, wherein the polysaccharide polymer is selected from the group consisting of polysaccharides and polysaccharide esters having a total degree of substitution of more than 0 and not more than 2.9. Item 3. The water-in-oil emulsion composition according to Item 1 or 2, wherein the polysaccharide polymer is selected from the group consisting of cellulose and cellulose esters. Item 4. The water-in-oil emulsion composition according to any one of Items 1 to 3, wherein the polysaccharide polymer is selected from the group consisting of cellulose and cellulose esters having a total degree of substitution of more than 0 and not more than 2.9. Item 5. Item 6. The water-in-oil emulsion composition according to any one of Items 1 to 4, wherein the polysaccharide polymer is selected from the group consisting of cellulose and cellulose esters having a total degree of substitution of more than 0 and not more than 2.5. Item 7. The water-in-oil emulsion composition according to any one of Items 1 to 6, wherein the polysaccharide polymer is selected from the group consisting of cellulose and cellulose esters having a total degree of substitution of more than 0 and not more than 1.0. Item 8. The water-in-oil emulsion composition according to any one of Items 1 to 6, wherein the water content in the water-in-oil emulsion composition is 20 to 70% by weight. Item 9. The water-in-oil emulsion composition according to any one of Items 1 to 8, wherein the particle content in the water-in-oil emulsion composition is 0.5 to 15% by weight. Item 10. Item 10. The water-in-oil emulsion composition according to any one of Items 1 to 9, further comprising a water-soluble salt of an acid having an average pKa value of -1 to 5. Item 11. The water-in-oil emulsion composition according to Item 10, comprising the salt in an amount such that the product of the number of moles of the anion of the acid and the valence of the anion is 0.0005 mole or more per 100 g of the water-in-oil emulsion composition. Item 12. A cosmetic composition comprising the water-in-oil emulsion composition according to any one of Items 1 to 11.Item 13. A method for producing a water-in-oil emulsion composition, comprising: Step A of preparing a water-in-oil base emulsion composition from an oil phase composition and an aqueous phase composition; and Step B of mixing the water-in-oil base emulsion composition with particles containing as a main component a polysaccharide polymer selected from the group consisting of polysaccharides and polysaccharide esters. Item 14. The production method according to Item 13, wherein Step B is carried out at 5 to 40°C.

[0011] According to the present disclosure, a water-in-oil emulsion composition is provided in which the dispersibility of polysaccharide particles is improved.

[0012] [1] Water-in-oil emulsion composition The water-in-oil emulsion composition of the present disclosure is characterized in that it contains particles (hereinafter, sometimes referred to as "polysaccharide particles") whose main component is a polysaccharide polymer selected from the group consisting of polysaccharides and polysaccharide esters in an oil phase, and the particles satisfy a predetermined dispersibility.

[0013] [1-1] Particles composed primarily of a polysaccharide polymer (polysaccharide particles) Particles composed primarily of a polysaccharide polymer are contained in the oil phase of the water-in-oil emulsion composition of the present disclosure. "Composed primarily of a polysaccharide polymer" means that the component most abundant in the particles is a polysaccharide polymer, and that the content of the polysaccharide polymer is 50% by weight or more. Preferred polysaccharide polymer contents in particles composed primarily of a polysaccharide polymer include 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, 98% by weight or more, and 99% by weight or more.

[0014] [1-1-1] Polysaccharide Polymer The polysaccharide polymer is selected from the group consisting of polysaccharides and polysaccharide esters.

[0015] Polysaccharides refer to polymeric compounds formed by the bonding of monosaccharides via glycosidic bonds. Polysaccharides may be polymers of α-glucose or β-glucose. More specific examples of polysaccharides include cellulose, hemicellulose, pullulan, amylose, agarose, chitin, chitosan, carrageenan, pectin, dextrin, starch, collagen, mannan, arabinogalactan, glycogen, inulin, hyaluronic acid, and modified forms thereof. As polysaccharides, one of these polymeric compounds may be used alone, or two or more may be used in combination. Among these polymeric compounds, cellulose is preferred as a polysaccharide. Commercially available polysaccharides may be used, or hydrolysates of polysaccharide esters, as described below, may be used. For example, commercially available cellulose may be used, or a fully saponified cellulose ester, such as cellulose acetate, may be used.

[0016] The polysaccharide ester is a carboxylic acid ester of the polysaccharide described above, and is defined as a compound in which some of the hydroxyl groups in the molecular chain are substituted with acyl groups. As the polysaccharide ester, one of the carboxylic acid esters of the polysaccharide described above may be used alone, or two or more may be used in combination. Among these polysaccharide esters, cellulose ester is preferred.

[0017] Specific examples of cellulose esters include cellulose acylates having an acyl group with two or more carbon atoms. Preferred examples of the number of carbon atoms in the acyl group include 3 or more, 4 or more, and 10 or less, 8 or less. Specific examples of cellulose acylates include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate. The cellulose acylate may have two or more types of acyl groups as substituents. One type of cellulose acylate may be used alone, or two or more types of cellulose acylates having acyl groups with different numbers of carbon atoms may be used in combination. Among these cellulose acylates, preferred are cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate, and more preferred is cellulose acetate (cellulose acetate).

[0018] The total degree of substitution of the polysaccharide ester is not particularly limited as long as it is greater than 0. The higher the total degree of substitution of the polysaccharide ester, the higher the hydrophobicity and the less likely it is to aggregate. Therefore, examples of the total degree of substitution of the polysaccharide ester include a degree of substitution greater than 0, preferably 0.05 or more, 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, 0.4 or more, and even more preferably 0.5 or more, or greater than 0 and 2.9 or less, preferably 0.05 to 2.9, 0.1 to 2.9, more preferably 0.2 to 2.9, even more preferably 0.3 to 2.9, 0.4 to 2.9, and even more preferably 0.5 to 2.9.

[0019] On the other hand, the water-in-oil emulsion composition of the present disclosure has excellent dispersibility for particles primarily composed of polysaccharide polymers, and therefore can well disperse even polysaccharide esters with a low total degree of substitution, which are inherently prone to aggregation. In other words, the water-in-oil emulsion composition of the present disclosure is particularly useful when using a polysaccharide ester with a low total degree of substitution. From this perspective, preferred examples of the total degree of substitution of the polysaccharide ester include more than 0 and 2.9 or less, more than 0 and 2.5 or less, more preferably more than 0 and 2.0 or less, more preferably more than 0 and 1.5 or less, even more preferably more than 0 and 1.0 or less, even more preferably more than 0 and 0.7 or less, more preferably more than 0 and 0.5 or less, and even more preferably more than 0 and 0.3 or less.

[0020] The total degree of substitution of the polysaccharide ester is 13 C-NMR or 1 The degree of substitution of cellulose acylate is measured by a known method using H-NMR. For example, the degree of substitution of cellulose acylate is measured by NMR according to the method of Tezuka (Tezuka, Carbonydr. Res. 273, 83 (1995)). In this measurement method, the free hydroxyl groups of cellulose acylate are acylated with a carboxylic acid anhydride in pyridine. The type of carboxylic acid anhydride used here should be selected depending on the purpose of analysis. For example, acetic anhydride is suitable for analyzing the degree of propionyl substitution of cellulose propionate. The obtained sample is dissolved in deuterated chloroform, and 13 C-NMR spectra are measured. When cellulose acylate containing or not containing propionyl groups is treated with propionic anhydride to analyze the degree of propionyl substitution, the signals of the carbonyl carbon of the propionyl group appear in the same order from 172 ppm to 174 ppm, from the high magnetic field to the 2nd, 3rd, and 6th positions. Since the total degree of substitution of cellulose acylate treated with carboxylic anhydride by Tezuka's method is 3.0, the sum of the areas of the carbonyl carbon signals of the acyl groups originally present in the cellulose acylate and the carbonyl signals of the acyl groups introduced by the carboxylic anhydride treatment is normalized to 3.0, and the abundance ratios of each acyl group at the corresponding positions (in other words, the area ratios of each signal) are calculated, which can be used to determine the degrees of acyl substitution at the 2nd, 3rd, and 6th positions of the glucose ring in the cellulose ester. Needless to say, the only acyl-containing substituents that can be analyzed by this method are those that do not correspond to the carboxylic anhydride used in the treatment for analysis. Also, 13 In addition to C-NMR, 1 It can also be analyzed by H-NMR.

[0021] [1-1-2] Other Particle Constituents The particles may contain other components as long as they are primarily composed of a polysaccharide polymer. Examples of other components include aliphatic polyesters, aliphatic polyols, aliphatic polycarbonates, and polyacid anhydrides. These other components are preferably biodegradable polymers. The particles may contain one type of these other components alone or two or more types in combination.

[0022] [1-1-3] Surface Morphology of Polysaccharide Particles Particles primarily composed of polysaccharide polymers may or may not be subjected to any surface treatment. Examples of such surface treatments include hydrophobic modification treatments, which may be selected to suppress aggregation when incorporated into a water-in-oil emulsion composition. Specific examples of hydrophobic modification treatments include inorganic powders (e.g., titanium oxide, silicon oxide, aluminum oxide, zinc oxide, zirconium oxide, magnesium oxide, boron nitride, silicon nitride, barium sulfate, calcium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, talc, mica, kaolin, sericite, mica, vermiculite, higilite, bentonite, montmorillonite, hectorite, kaolinite, zeolite, ceramic powder, hydroxyapatite, calcium phosphate, silicic acid, aluminum silicate, magnesium silicate, magnesium aluminum silicate, calcium silicate, etc.), metal soaps (e.g., non-alkali metal salts of higher (e.g., carbon atoms 12 to 25) fatty acids), cationic surfactants (e.g., quaternary ammonium salts, etc.), silane coupling agents (e.g., alkyl (e.g., carbon atoms 1 to 4) silane), amino acid derivatives (e.g., Nε-lauroyl-L-lysine, etc.), phospholipid-based treatment agents, glycolipid-based treatment agents, complex lipid-based treatment agents, ceramide-based treatment agents, and the like. Surface treatments using such agents are also possible. These compounds and particles may be physically attached to each other, or may be ionically or covalently bonded to each other.

[0023] The water-in-oil emulsion composition of the present disclosure has excellent dispersibility of polysaccharide particles, and therefore can disperse the particles well even if the particles are not surface-treated to be hydrophobized, which is inherently prone to aggregation. In other words, the water-in-oil emulsion composition of the present disclosure is particularly useful when using polysaccharide particles whose surfaces have not been hydrophobized. From this perspective, preferred surface morphologies of polysaccharide particles include those that have not been hydrophobized.

[0024] [1-1-4] Characteristics of Polysaccharide-Based Particles The particle size variation coefficient CV of particles mainly composed of a polysaccharide polymer is not particularly limited, but is, for example, 40% or less, preferably 38% or less, and 35% or less, and also 0% or more, 2% or more. The particle size variation coefficient is calculated by the following formula using the average particle size and standard deviation of particle sizes described below: Particle size variation coefficient (%) = standard deviation of particle sizes / average particle size × 100

[0025] The average particle size of the particles containing a polysaccharide polymer as a main component is not particularly limited, and examples thereof include 0.08 to 100 μm, 0.1 to 80 μm, 1.0 to 40 μm, 2.0 to 20 μm, 4.0 to 10 μm, and 5.0 to 8.0 μm.

[0026] The average particle size and the particle size variation coefficient are measured using a dynamic light scattering method. Specifically, the average particle size is the particle size (volume-based median size) corresponding to an integrated value of 50% of the scattering intensity in the volume frequency particle size distribution measured using the dynamic light scattering method, and the particle size variation coefficient is a value calculated by (standard deviation of particle sizes / average particle size)×100.

[0027] The sphericity of the particles containing a polysaccharide polymer as a main component is not particularly limited, but examples thereof include 0.7 to 1.0, 0.8 to 1.0, and 0.9 to 1.0.

[0028] The sphericity is measured by the following method. It is the average value of the minor axis / major axis ratio based on an image of a particle observed with a scanning electron microscope (SEM). The closer the sphericity is to 1, the more spherical the particle is.

[0029] The surface smoothness of particles containing a polysaccharide polymer as a main component is not particularly limited, but examples include 80 to 100%, 85 to 100%, 90 to 100%, 95 to 100%, and 98 to 100%.

[0030] The surface smoothness of the particles is determined by taking a scanning electron microscope photograph of the particles, observing the irregularities on the particle surface, and calculating the area of ​​the depressions.

[0031] [1-1-5] Content of Polysaccharide Particles The content of particles mainly composed of polysaccharide polymers in the water-in-oil emulsion composition of the present disclosure is not particularly limited, and may be, for example, 0.5 to 15 wt %, preferably 0.8 to 12 wt %, 1 to 10 wt %, more preferably 2 to 8 wt %, and even more preferably 3 to 7 wt %, or 4 to 6 wt %.

[0032] In the water-in-oil emulsion composition of the present disclosure, the ratio of the content of water to the content of particles having a polysaccharide polymer as a main component is not particularly limited, but the content of particles having a polysaccharide polymer as a main component per 100 parts by weight of water may be, for example, 1 to 50 parts by weight, 1 to 40 parts by weight, preferably 1 to 30 parts by weight, 1 to 20 parts by weight, more preferably 2 to 17 parts by weight, even more preferably 5 to 15 parts by weight, and even more preferably 7 to 13 parts by weight, or 8 to 12 parts by weight.

[0033] [1-1-6] Dispersibility of Polysaccharide Particles: In the water-in-oil emulsion composition of the present disclosure, particles primarily composed of a polysaccharide polymer are well dispersed in the oil phase. The specific dispersibility of particles primarily composed of a polysaccharide polymer in the water-in-oil emulsion composition of the present disclosure is 130 μm or less, as measured using a grind gauge. Preferred ranges of dispersibility in the water-in-oil emulsion composition of the present disclosure include 120 μm or less, 110 μm or less, more preferably 100 μm or less, 95 μm or less, 90 μm or less, 85 μm or less, 80 μm or less, 75 μm or less, 70 μm or less, 65 μm or less, 60 μm or less, 55 μm or less, and even more preferably 50 μm or less, 45 μm or less, or 43 μm or less, and also include 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, and 30 μm or more. Specific ranges of dispersibility include 0 to 130 μm, 0 to 120 μm, and 0 to 110 μm, more preferably 10 to 100 μm, 10 to 95 μm, 10 to 90 μm, 15 to 85 μm, 15 to 80 μm, 15 to 75 μm, 20 to 70 μm, 20 to 65 μm, 20 to 60 μm, and 25 to 55 μm, and even more preferably 25 to 50 μm, 30 to 45 μm, and 30 to 43 μm.

[0034] [1-2] Basic Components The water-in-oil emulsion composition of the present disclosure can contain, as its basic components, any components that can be used to form a general water-in-oil emulsion composition, without limitation. The water-in-oil emulsion composition of the present disclosure can be produced, for example, by the unique production method described below. In other words, by adding polysaccharide particles after preparing a water-in-oil emulsion, contact between the polysaccharide particles and the water contained in the emulsion membrane is inhibited, thereby enabling the polysaccharide particles, which are inherently prone to aggregation, to be well dispersed in the oil phase. Therefore, the type of oily base and the type of surfactant do not affect the water-in-oil emulsion composition of the present disclosure's ability to achieve the above-mentioned predetermined dispersibility (130 μm or less as measured using a grind gauge).

[0035] [1-2-1] Oily Base Examples of oily bases include oils that are liquid or semi-solid (viscous and freely deformable) at 25°C, specifically hydrocarbon oils [for example, linear or branched hydrocarbon oils such as liquid paraffin, light isoparaffin (isododecane), liquid isoparaffin, petrolatum, mineral oil, polybutene, polyisobutene, hydrogenated polydecene, squalane, and squalene]; vegetable oils [for example, avocado oil, macadamia nut oil, olive oil, rapeseed oil, sesame oil, wheat germ oil, linseed oil, cottonseed oil, soybean oil, palm oil, coconut oil, castor oil, jojoba oil, sunflower oil, camellia oil, and corn oil]; and animal oils [for example, liquid lanolin and paste-like lanolin].Ester oils [e.g., isopropyl myristate, octyldodecyl myristate, isopropyl isostearate, isononyl isononanoate, butyl stearate, oleyl oleate, isotridecyl isononanoate, isostearyl myristate, octyldodecyl ricinoleate, octyl hydroxystearate, diglyceryl monoisostearate, ethylhexyl palmitate, cetyl ethylhexanoate, octyl methoxycinnamate, tocopheryl acetate, diisostearyl malate, dicaprylyl glycol diglyceride, methylparaben ... Propylene glycol diacrylate, neopentyl glycol dicaprate, neopentyl glycol diethylhexanoate, diglyceryl diisostearate, propanediol diisostearate, glyceryl monomyristate monoisostearate, glyceryl diisostearate, glyceryl triisostearate, propanediol dicaprate / caprylate, glyceryl tricaprylate / caprate, glyceryl tri-2-ethylhexanoate, triethylhexanoin, tri-2-ethylhexane Trimethylolpropane triisostearate, trimethylolpropane triisostearate, pentaerythrityl tetraoctanoate, pentaerythrityl tetraethylhexanoate, pentaerythritol tetraisostearate, polyglyceryl-2 isostearate, polyglyceryl-2 diisostearate, polyglyceryl-2 triisostearate, polyglyceryl-2 tetraisostearate, polyglyceryl-6 octacaprylate, ditrimethylolpropane oligoester of isostearic acid / sebacic acid, lauroyl glutamic acid di(phytosteryl / octyldodecyl), lauroyl glutamic acid di(phytosteryl / behenyl / octyldodecyl), isostearic acid trehalose esters, ethylhexyl hydroxystearate, phytosterol fatty acid esters, cholesterol fatty acid esters, polyglycerin fatty acid esters, pentaerythritol fatty acid esters, dl-α-tocopherol, nicotinic acid dl-α-tocopherol, etc.; higher alcohols [for example, octyldodecanol, etc.];Examples of suitable oils include silicone oils (diphenyldimethicone, dimethylpolysiloxane (dimethicone), methylcyclopolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, higher alcohol-modified organopolysiloxane, tris(trimethylsiloxy)methylsilane, etc.); and fluorine oils (e.g., fluoropolyether, perfluoroalkyl ether silicone, etc.).

[0036] Further, examples of the oily base include oils that are solid at 25°C. Specific examples include monohydric alcohols having 14 to 34 carbon atoms [e.g., higher alcohols such as myristyl alcohol, cetyl alcohol, stearyl alcohol, isostearyl alcohol, behenyl alcohol, hexadecyl alcohol, and lanolin alcohol]; petroleum waxes [e.g., microcrystalline wax]; vegetable waxes [e.g., carnauba wax, candelilla wax, rice wax, and Japan wax]; animal waxes [e.g., beeswax and whale wax]; synthetic waxes [e.g., silicone wax and polyethylene wax]; and higher fatty acids.

[0037] These oily bases may be used alone or in combination of two or more. Of these oily bases, it is preferable to use oils that are liquid or semi-solid at least at 25°C, and it is more preferable to use oils that are liquid at least at 25°C.

[0038] The content of the oily base in the water-in-oil emulsion composition of the present disclosure is not particularly limited, and examples include 10 to 70% by weight, 10 to 65% by weight, 10 to 50% by weight, 10 to 40% by weight, 10 to 30% by weight, 12 to 25% by weight, and 14 to 20% by weight.

[0039] [1-2-2] Surfactants Examples of surfactants include nonionic surfactants and anionic surfactants. Other examples of surfactants include silicone surfactants. For example, one of the three types of surfactants, nonionic surfactants, anionic surfactants, and silicone surfactants, may be used alone, or two or more types may be used in combination. Among these surfactants, nonionic surfactants are preferred, and when silicone oil is used as the oily base, silicone surfactants are preferred. Furthermore, examples of surfactants include hydrophilic surfactants and lipophilic surfactants, and either one of these may be used, or both may be used in combination.

[0040] Examples of nonionic surfactants include ethylene oxide condensation type nonionic surfactants, polyhydric alcohol ester type nonionic surfactants, and polyhydric alcohol condensation type nonionic surfactants. Examples of ethylene oxide condensation type nonionic surfactants include polyoxyethylene alkyl ethers [e.g., laureth-n, ceteth-n, steareth-n, ceteareth-n, beheneth-n, oleth-n, trideceth-n, isoceteth-n, isosteareth-n, octyldodeceth-n, (C12-14) pareth-n, (C12-14) s-pareth-n, etc.]; polyoxyethylene steryl ethers [e.g., cholestrol-n, PEG-n phytosterol, etc.]; polyoxyethylene polyoxypropylene alkyl ethers [e.g., PPG-2-deceth-n, PPG-4 ceteth-n, PPG-8 ceteth-n, PPG-6 decyltetradeceth-n, etc.]; polyoxyethylene fatty acid esters [for example, PEG-n laurate, PEG-n stearate, PEG-n isostearate, PEG-n distearate, etc.]; polyoxyethylene polyhydric alcohol fatty acid esters [for example, PEG-n glyceryl coconut oil fatty acid, PEG-n glyceryl stearate, PEG-n glyceryl isostearate, PEG-n glyceryl triisostearate, sorbeth-n tetraoleate, etc.]; polyoxyethylene hydrogenated castor oil; and polyoxyethylene sorbitan fatty acid esters.Examples of polyhydric alcohol ester-type nonionic surfactants include glycol fatty acid esters [e.g., PG stearate, PG stearate (SE), etc.]; glycerin fatty acid esters [e.g., glyceryl stearate, glyceryl stearate (SE), glyceryl isostearate, glyceryl oleate, glyceryl behenate, etc.]; sorbitan fatty acid esters [e.g., sorbitan laurate, sorbitan palmitate, sorbitan stearate, sorbitan isostearate, sorbitan oleate, sorbitan sesquistearate, sorbitan sesquiisostearate, sorbitan sesquioleate, sorbitan trioleate, sorbitan tristearate, olive oil, etc.]; sorbitan oil fatty acid, sorbitan coconut fatty acid, etc.); sucrose fatty acid esters [for example, sucrose laurate, sucrose palmitate, sucrose stearate, sucrose distearate, sucrose polystearate, etc.]; polyglycerin fatty acid esters [for example, polyglyceryl-n laurate, polyglyceryl-n myristate, polyglyceryl-n stearate, polyglyceryl-n oleate, polyglyceryl-n isostearate, polyglyceryl-n diisostearate, polyglyceryl-n polyricinoleate, polyglyceryl-n pentastearate, polyglyceryl-n pentaisostearate, polyglyceryl-n pentaoleate, etc.]. Examples of polyhydric alcohol condensation type nonionic surfactants include fatty acid alkanolamides [e.g., cocamide DEA, cocamide MEA, lauramide DEA, etc.]; and alkyl glycosides [e.g., (C12-20) alkyl glucoside, arachyl glucoside, (caprylyl / capryl) glucoside, decyl glucoside, lauryl glucoside, cetearyl glucoside, coconut oil alkyl glucoside, etc.].

[0041] These nonionic surfactants may be used alone or in combination of two or more. Among these nonionic surfactants, polyhydric alcohol ester-type nonionic surfactants are preferred, and polyglycerin fatty acid esters are more preferred.

[0042] Examples of silicone surfactants include linear silicone surfactants, branched silicone surfactants, and crosslinked silicone surfactants. Examples of linear silicone surfactants include polyether-modified silicone surfactants [e.g., PEG-n dimethicone, PEG-n methyl ether dimethicone, polysilicone-13, etc.] and polyether / alkyl-co-modified silicone surfactants [e.g., cetyl PEG / PPG-10 / 1 dimethicone, etc.]. Examples of branched silicone surfactants include polyether-modified silicone surfactants [for example, PEG-9 polydimethylsiloxyethyl dimethicone, etc.]; polyglycerin-modified silicone surfactants [for example, polyglyceryl-3 disiloxydimethicone, polyglyceryl-3 polydimethylsiloxyethyl dimethicone, etc.]; polyether / alkyl co-modified silicone surfactants [for example, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, etc.]; and polyglycerin / alkyl co-modified silicone surfactants [for example, lauryl polyglyceryl-3 polydimethylsiloxyethyl dimethicone, etc.]. Examples of crosslinked silicone surfactants include polyether-modified silicone surfactants [for example, (dimethicone / (PEG-10 / 15)) crosspolymer, etc.]; polyglycerin-modified silicone surfactants [for example, (dimethicone / polyglycerin-3) crosspolymer, etc.]; polyether / alkyl co-modified silicone surfactants [for example, (PEG-15 / lauryl dimethicone) crosspolymer, etc.]; polyglycerin / alkyl co-modified silicone surfactants [for example, (lauryl dimethicone / polyglycerin-3) crosspolymer, etc.]; and polyether / silicone / alkyl co-modified silicone surfactants [for example, (PEG-15 / lauryl polydimethylsiloxyethyl dimethicone) crosspolymer, etc.].

[0043] These silicone surfactants may be used alone or in combination of two or more. Among these silicone surfactants, branched silicone surfactants are preferred, and polyether-modified silicone surfactants are more preferred.

[0044] The content of the surfactant in the water-in-oil emulsion composition of the present disclosure is not particularly limited, but examples include 0.5 to 8 wt %, 0.5 to 7 wt %, 0.5 to 6 wt %, 0.5 to 5 wt %, 1 to 4 wt %, 1.5 to 3.5 wt %, 2 to 3 wt %, and 2 to 2.5 wt %.

[0045] [1-2-3] Water The amount of water contained in the water-in-oil emulsion composition of the present disclosure is not particularly limited, but examples include 20 to 70 wt %, 30 to 70 wt %, 40 to 70 wt %, 45 to 65 wt %, and 50 to 60 wt %.

[0046] [1-3] Prescribed Salt The water-in-oil emulsion composition of the present disclosure preferably contains a prescribed salt from the viewpoint of further improving the dispersibility of the polysaccharide particles.

[0047] As the predetermined salt, a water-soluble salt of an acid having an average pKa value of -1 to 5 is used.

[0048] In this disclosure, pKa refers to the acid dissociation constant in water, which is the negative common logarithm pKa (pKa = -log 10 The pKa is expressed by the formula (pKa = pKa ≡ 1 / 2 sq. mtr, ...

[0049] Here, the predetermined salt is represented by the formula A x (H y B) z(In the formula, A represents an n-valent cation other than a proton, B represents an m-valent anion derived from an m-valent acid, H represents a proton, x represents an integer of 1 or more, y represents an integer of 0 or more, z represents an integer of 1 or more, and nx=z(m−y)).

[0050] In this specification, the average pKa value is the average value of the acid from which a given salt is derived, i.e., the m-ary acid (composition formula: H x+y When the m-valent acid is a monobasic acid (x + y = 1), the average pKa is equal to one pKa value of the monobasic acid. When the m-valent acid is a polybasic acid (x + y ≥ 2), and the salt is a normal salt (y = 0), the average pKa of the polybasic acid (x + y) is equal to one pKa value of the polybasic acid (pKa1, ...pKa2). x+y ) and when the salt is an acid salt (y≧1), the polyacid has (x+y) pKa (pKa1, ...pKa x , ...pKa x+y ) among pKa1, ... pKa x is the average value of

[0051] In the above composition formula, specific examples of A include metal ions of alkali metals (potassium, sodium, etc.), alkaline earth metals (magnesium, potassium, etc.), ammonium ions, etc. x+y Specific examples of B) include sulfuric acid (pKa1=-3.0, Ka2=1.9), acetic acid (pKa=4.76), phosphoric acid (pKa1=2.12, pKa2=7.21, pKa3=12.32), citric acid (pKa1=3.09, pKa2=4.75, pKa3=5.41), lactic acid (pKa=3.86), and ethylenediaminetetraacetic acid (pKa1=2.00, pKa2=2.67, pKa3=6.16, pKa4=10.26).

[0052] Examples of certain salts that can be used in the present disclosure include magnesium sulfate, trisodium citrate, disodium ethylenediaminetetraacetate, trisodium ethylenediaminetetraacetate, calcium diacetate, disodium sulfate, sodium acetate, dipotassium sulfate, potassium acetate, lithium sulfate, lithium acetate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and dilithium hydrogen phosphate.

[0053] The water solubility of a given salt is not particularly limited as long as it can be dissolved in the aqueous phase of the water-in-oil emulsion composition. For example, the solubility in 100 g of water at 20°C is 0.6 g or more, preferably 5 g or more, and more preferably 10 g or more.

[0054] Without being bound by theory, the mechanism by which the inclusion of the specified salt further improves the dispersion of polysaccharide particles is thought to be as follows: The specified salt ionizes in water, and the ionized ions solvate. Due to solvation, water molecules bond to the ions to form molecular groups, resulting in delocalization of the charge of the water molecules. It is believed that this delocalization of the charge of the water molecules reduces the hydrogen bonds between the hydroxyl groups of the polysaccharide particles and the water molecules, thereby further improving the aggregation-inhibiting effect due to the chain of hydrogen bonds between the polysaccharide particles and the water molecules. Furthermore, the more stable the ions are in the ionic state, the more stable the solvation becomes, and the better the delocalized state of the charge of the water molecules is maintained, which tends to enhance the aggregation-inhibiting effect. Meanwhile, among the ions generated by ionization, anions can be reprotonated depending on the pKa of the acid from which they are derived. The higher the pKa of the acid from which the anions are derived, the more ions are protonated due to ionization equilibrium, which tends to reduce the stability of the solvation by the specified salt and reduce the effect of improving aggregation inhibition. In order to effectively obtain the effect of improving the aggregation suppression by including a predetermined salt, it is appropriate that the upper limit of the pKa of the acid derived from the predetermined salt is about 5.

[0055] From the viewpoint of further improving the dispersibility of the polysaccharide particles, the average pKa of the acid from which the predetermined salt is derived is preferably −1 to 4.7 or −1 to 4.5, more preferably −1 to 3.3, −1 to 3, or −1 to 2.5, and even more preferably −1 to 0.8, −1 to 0.5, −1 to 0, −1 to −0.2, or −0.8 to −0.2.

[0056] The amount of the predetermined salt to be added is not particularly limited. However, it is preferable that the amount of the anion of the predetermined salt (general formula: H y B (m-y)-The product of the number of moles of the anion of the predetermined salt and the valence of the anion (m-y) is, for example, 0.0005 mol or more, preferably 0.001 mol or more or 0.003 mol or more, and more preferably 0.005 mol or more, 0.01 mol or more, 0.015 mol or more, 0.02 mol or more, or 0.03 mol or more. There is no particular upper limit on the amount of the predetermined salt added, and examples of the product of the number of moles of the anion of the predetermined salt and the valence of the anion in 100 g of the water-in-oil emulsion composition include 0.5 mol or less, 0.4 mol or less, 0.35 mol or less, 0.3 mol or less, 0.25 mol or less, 0.2 mol or less, 0.15 mol or less, 0.1 mol or less, or 0.05 mol or less. Specific ranges for the product of the number of moles of an anion of a predetermined salt and the valence of the anion in 100 g of the water-in-oil emulsion composition include 0.001 to 0.5 mol, or 0.003 to 0.5 mol, more preferably 0.005 to 0.5 mol, 0.01 to 0.5 mol, 0.015 to 0.5 mol, 0.02 to 0.5 mol, or 0.03 to 0.5 mol, 0.03 to 0.4 mol, 0.03 to 0.35 mol, 0.03 to 0.3 mol, 0.03 to 0.25 mol, 0.03 to 0.2 mol, 0.03 to 0.15 mol, 0.03 to 0.1 mol, or 0.03 to 0.05 mol.

[0057] [1-4] Other Components In addition to the components described above, the water-in-oil emulsion composition of the present disclosure may or may not contain other additives depending on the intended use and / or formulation. Examples of such additives that may or may not be present include inorganic particles, texture improvers, thickeners, humectants, solubilizers, buffers, chelating agents, preservative aids, preservatives, preservatives, antioxidants, stabilizers, chelating agents, fragrances, colorants, and the like. When these additives are contained in the water-in-oil emulsion composition of the present disclosure, one type may be used alone, or two or more types may be used in combination. Furthermore, when these additives are contained in the water-in-oil emulsion composition of the present disclosure, the content thereof may be appropriately determined depending on the type of additive used, etc.

[0058] Examples of inorganic particles include titanium oxide, silicon oxide, aluminum oxide, zinc oxide, zirconium oxide, magnesium oxide, boron nitride, silicon nitride, barium sulfate, calcium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, talc, mica, kaolin, sericite, mica, vermiculite, higilite, bentonite, montmorillonite, hectorite, kaolinite, zeolite, ceramic powder, hydroxyapatite, calcium phosphate, silicic acid, aluminum silicate, magnesium silicate, aluminum magnesium silicate, and calcium silicate. When using these inorganic particles, one type may be used alone, or two or more types may be used in combination. Among these inorganic particles, titanium oxide and zinc oxide are preferred.

[0059] As the feel improver, a feel improver other than particles mainly composed of polysaccharide polymers is used, and examples thereof include crosslinked silicone powder (more specifically, so-called silicone rubber powder composed of organopolysiloxane having a structure in which repeating chains of diorganosiloxane units are crosslinked), acrylic polymers such as methyl methacrylate crosspolymer, non-crosslinked cellulose, porous silica, etc. These feel improvers may be swollen substances containing silicone oil. When these feel improvers are used, one type may be used alone, or two or more types may be used in combination. Among these feel improvers, crosslinked silicone powder is preferred. Specific examples of crosslinked silicone powder include (dimethicone / vinyl dimethicone) crosspolymer, etc.

[0060] Examples of thickeners include water-soluble thickeners and oil-soluble thickeners. Examples of water-soluble thickeners include inorganic salts (other than the above-mentioned specified salts), specifically alkali metal or alkaline earth metal salts, more preferably alkali metal or alkaline earth metal salts of acids (e.g., hydrochloric acid) having an average pKa value of less than -1, more specifically sodium chloride, potassium chloride, magnesium chloride, calcium chloride, etc. In one embodiment of the water-in-oil emulsion composition of the present disclosure, the composition does not contain one or more inorganic salts (other than the above-mentioned specified salts) that can be used as the water-soluble thickeners, and preferably does not contain inorganic salts (other than the above-mentioned specified salts) that can be used as the water-soluble thickeners. Examples of oil-soluble thickeners include metal soaps (aluminum stearate, magnesium stearate, zinc myristate, etc.); amino acid derivatives (N-lauroyl-L-glutamic acid, α,γ-di-n-butylamine, etc.); dextrin fatty acid esters (dextrin palmitate, dextrin stearate, dextrin 2-ethylhexanoic acid palmitate, etc.); fructooligosaccharide fatty acid esters (fructooligosaccharide stearate, fructooligosaccharide 2-ethylhexanoate, etc.); benzylidene derivatives of sorbitol (monobenzylidene sorbitol, dibenzylidene sorbitol, etc.); and organically modified clay minerals (disteardimonium hectorite, stearalkonium hectorite, hectorite, etc.). When these thickeners are used, one type may be used alone, or two or more types may be used in combination. Among these thickeners, preferred are mineral acid salts of alkali metals or alkaline earth metals and organically modified clay minerals.

[0061] Examples of the moisturizing agent, solubilizing agent, or antiseptic adjuvant include polyhydric alcohols, and specific examples thereof include dihydric alcohols (1,3-butylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, isoprene glycol, 1,2-pentanediol, 1,2-hexanediol, octanediol, etc.) and trihydric alcohols (glycerin, etc.).

[0062] [1-5] Dosage Forms and Product Classifications The dosage forms of the water-in-oil emulsion composition of the present disclosure include liquid preparations such as emulsions; semi-solid preparations such as gels and creams; oily solid preparations; and aerosol preparations.

[0063] Product categories for the water-in-oil emulsion composition of the present disclosure include cosmetics, such as liquid foundation, cream foundation, cushion foundation, cream foundation, gel foundation, stick foundation, and spray foundation; concealer; sunscreen emulsion, sunscreen cream, and sunscreen spray; makeup base, BB cream, and BB spray; blush, eye shadow, mascara, eyeliner, and eyebrow pencil; lipstick, lipstick base, and lip coat; wrinkle concealing cream; skin care lotion, skin care emulsion, skin care cream, and beauty serum; and hair styling products.

[0064] [2] Manufacturing method of water-in-oil emulsion composition The manufacturing method of the present disclosure is the manufacturing method of the water-in-oil emulsion composition described above in "[1] Water-in-oil emulsion composition." Specifically, the manufacturing method of the present disclosure is characterized by comprising: Step A of preparing a water-in-oil base emulsion composition from an oil phase composition and an aqueous phase composition; and Step B of mixing the water-in-oil base emulsion composition with particles primarily composed of a polysaccharide polymer selected from the group consisting of polysaccharides and polysaccharide esters.

[0065] [2-1] Step A In Step A, a water-in-oil emulsion composition for a base is prepared from an oil phase composition and an aqueous phase composition. The oil phase composition contains an oil phase base and, if necessary, oil-soluble components (lipophilic surfactants, oil-soluble thickeners, and / or other oil-soluble components), inorganic particles, and / or a texture improver. The aqueous phase composition contains water and, if necessary, water-soluble components (hydrophilic surfactants, water-soluble thickeners, polyhydric alcohols, and / or other water-soluble components). Neither the oil phase composition nor the aqueous phase composition contains particles primarily composed of polysaccharide polymers. Details of the components constituting the oil phase composition and the aqueous phase composition are as described above in "[1-2] Basic Components," "[1-3] Prescribed Salts," and "[1-4] Other Components."

[0066] A known water-in-oil emulsification method can be used to prepare the water-in-oil base emulsion composition. For example, a heated (preferably 70 to 80°C) aqueous phase composition can be added to a heated (preferably 70 to 80°C) oil phase composition while stirring, and emulsified.

[0067] As the emulsification method, a known method can be used, and for example, the emulsification can be carried out using a known emulsification device such as a homomixer, a disper mixer, an ultra mixer, a high-pressure homogenizer, or a micromixer.

[0068] [2-2] Step B In step B, the water-in-oil emulsion composition for a base is mixed with particles (polysaccharide particles) whose main component is a polysaccharide polymer selected from the group consisting of polysaccharides and polysaccharide esters. Preferably, the polysaccharide particles are mixed in a state where they are dispersed in an oily base. Details of the polysaccharide particles are as described above in "[1-1] Particles whose main component is a polysaccharide polymer (polysaccharide particles)," and details of the oily base are as described above in "[1-2-1] Oily base."

[0069] By mixing polysaccharide particles with a previously prepared water-in-oil emulsion composition for base, the polysaccharide particles are dispersed in the oil phase of the water-in-oil emulsion composition for base. In the water-in-oil emulsion composition for base, the aqueous phase is encapsulated in an emulsion membrane, and it is thought that the already formed emulsion membrane inhibits contact between the hydroxyl groups of the polysaccharide particles added in step B and the water in the aqueous phase. This suppresses aggregation of the polysaccharide particles, enabling them to be well dispersed in the resulting water-in-oil emulsion composition.

[0070] From the viewpoint of further improving the dispersibility of polysaccharide particles in the resulting water-in-oil emulsion composition, step B is preferably carried out at 5 to 40°C, 10 to 40°C, or 20 to 40°C, more preferably at 25 to 35°C, and even more preferably at 30 to 35°C. Generally, when dispersing solid particles in an oil phase composition, heating the oil phase composition to about 70 to 80°C promotes mechanical disintegration of the solid particles into primary particles, thereby improving dispersibility. However, in the production method of the present disclosure, the unique effect of further improving the dispersibility of polysaccharide particles is achieved by not employing the heating method (70 to 80°C), which is generally employed to improve dispersibility. The mechanism by which this unique effect is achieved is thought to be that lowering the temperature of the already prepared water-in-oil base emulsion composition suppresses the thermal movement of the various components and relatively further stabilizes the emulsion film, thereby further inhibiting contact between the hydroxyl groups of the polysaccharide particles added in step B and the water in the aqueous phase.

[0071] Each feature disclosed herein may be combined with any other feature disclosed herein.

[0072] The present invention will be described in more detail below with reference to examples, but the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations may be made as appropriate within the scope of the present invention. The present disclosure is not limited by the embodiments, but is limited only by the scope of the claims.

[0073] [Test Example 1] [1] Preparation of Polysaccharide-Based Particles The particles shown in Table 1 were used as polysaccharide-based particles. None of the particles had been subjected to a hydrophobic treatment on the surface. Furthermore, all of the particles consisted solely of the polysaccharide-based polymer shown in Table 1. The instrument sensitivity, average particle size, particle size variation coefficient, sphericity, and surface smoothness of each particle were measured using the following methods.

[0074] <Total degree of substitution> The total degree of substitution is 1 It was determined by H-NMR analysis.

[0075] <Average particle size and particle size variation coefficient> Particles were added to pure water to adjust the concentration to about 100 ppm, and a suspension was prepared using an ultrasonic vibration device. Subsequently, the volume frequency particle size distribution was determined and the average particle size was measured using a laser diffraction method (HORIBA, Ltd., "Laser Diffraction / Scattering Particle Size Distribution Analyzer LA-960" ultrasonic treatment for 15 minutes, refractive index (1.500, medium (water; 1.333)). The average particle size (μm) was taken as the particle size value (volume-based median diameter) corresponding to an integrated scattering intensity of 50% in the volume frequency particle size distribution. The particle size variation coefficient (%) was calculated by (standard deviation of particle size / average particle size) × 100. The results are shown in Table 1.

[0076] <Sphericity> Using images of particles observed with a scanning electron microscope (SEM), the major and minor axes of 30 randomly selected particles were measured, the minor axis / major axis ratio of each particle was calculated, and the average value of the minor axis / major axis ratios was taken as the sphericity. The results are shown in Table 1.

[0077] <Surface Smoothness> Images of particles observed with a scanning electron microscope (SEM) were binarized using an image processing device, Winroof (manufactured by Mitani Shoji Co., Ltd.). From the binarized image, a region including the center and / or vicinity of a single particle was randomly selected, and the area ratio of the concave portions (shaded portions) of the irregularities in that region was calculated. The surface smoothness (%) of that single particle was calculated using the following formula: Surface smoothness (%) of a single particle = (1 - concave area ratio) x 100 Concave area ratio = area of ​​concave portions in the arbitrary region / The average value of the surface smoothness of 10 particle samples (n1 to n10) randomly selected from the arbitrary region was taken as the surface smoothness (%). The larger this value, the higher the surface smoothness of the particle. The region used to calculate the area ratio may be any region smaller than the particle, including the center and / or vicinity of a single particle. The size of the region may be 5 μm square when the particle diameter is 15 μm.

[0078]

[0079] [2] Preparation of water-in-oil emulsion compositions Various water-in-oil emulsion compositions shown in Table 2 were prepared.

[0080] [2-1] Examples 1 to 3 In Table 2, an aqueous phase composition containing the components indicated under (I) in the indicated ratios was prepared at 70°C. An oil phase composition containing the components indicated under (II) in the indicated ratios was prepared using Disper dispersion at 70°C. A particle dispersion composition containing the components indicated under (III) in the indicated ratios was prepared using Disper dispersion at 70°C and then cooled to 35°C. While dispersing an oil phase composition (70°C) containing component (II) using Disper dispersion, an aqueous phase composition (70°C) containing component (I) was added to perform water-in-oil emulsification (Disper dispersion at 3,500 rpm for 2 minutes) to prepare a water-in-oil base emulsion composition. The water-in-oil base emulsion composition was cooled to 35°C, and a particle dispersion composition (35°C) containing component (III) was added and mixed (Disper dispersion at 1,500 rpm for 2 minutes), followed by degassing to obtain a water-in-oil emulsion composition.

[0081] [2-2] Examples 4 to 6 In Table 2, an aqueous phase composition containing the components indicated under (I) in the ratios shown was prepared at 70°C. An oil phase composition containing the components indicated under (II) in the ratios shown was prepared using Disper dispersion at 70°C. A particle dispersion composition containing the components indicated under (III) in the ratios shown was prepared using Disper dispersion at 70°C. While dispersing an oil phase composition (70°C) containing component (II) with Disper dispersion, an aqueous phase composition (70°C) containing component (I) was added, and water-in-oil emulsification was performed (Disper dispersion at 3,500 rpm for 2 minutes) to prepare a water-in-oil base emulsion composition. A particle dispersion composition (70°C) containing component (III) was added to the water-in-oil base emulsion composition (70°C) and mixed (Disper dispersion at 1,500 rpm for 2 minutes), followed by degassing to obtain a water-in-oil emulsion composition.

[0082] [2-3] Comparative Examples 1 to 3 An aqueous phase composition containing the component (I) in Table 2 in the ratio shown was prepared at 70°C. The components (II) and (III) were mixed in the ratio shown, and an oil phase composition was prepared at 70°C by Disper dispersion. While dispersing the oil phase composition (70°C) containing the components (II) and (III) with Disper, an aqueous phase composition (70°C) containing the component (I) was added to perform water-in-oil emulsification (Disper 3500 rpm, 2 minutes), followed by degassing to obtain a water-in-oil emulsion composition.

[0083] [3] Evaluation of dispersibility The dispersibility of the polysaccharide particles in the obtained water-in-oil emulsion compositions was confirmed by the following method, immediately after preparation (initial stage), after standing at room temperature (25°C) for one month, and after standing at 40°C for one month.

[0084] [3-1] Dispersibility was evaluated by visually inspecting the appearance of the water-in-oil emulsion composition. Specifically, the water-in-oil emulsion composition was spread thinly and uniformly on a black plastic spatula. Photographs of the appearance are shown in Tables 3 to 5.

[0085] [3-2] Micrographs and Evaluation of Dispersibility Based Thereon: A water-in-oil emulsion composition was dropped onto a glass slide, and a cover glass was placed on top. The water-in-oil emulsion composition was spread thinly enough that light could be transmitted through the sample and cellulose acetate particles could be observed. Micrographs are shown in Tables 3 to 5. In the micrographs shown in Tables 3 to 5, the scale bar size is 200 μm. Furthermore, the degree of dispersibility was evaluated on a 10-point scale, with a score of "1" representing the degree of dispersibility based on the size of aggregates after one month at 40°C in Comparative Example 1 and a score of "10" representing the degree of dispersibility based on the size of aggregates at the initial stage in Example 1. A higher dispersibility score indicates smaller aggregates and better dispersibility. The dispersibility scores are shown in Tables 2 to 5.

[0086] [3-3] Evaluation of dispersibility using a grind gauge A water-in-oil emulsion composition (left at room temperature (25°C) for one month) was dropped onto the gauge surface of a grind gauge (groove depth 0-200 μm), and the water-in-oil emulsion composition was scraped off with a metal scraper to form a coating film. Linear scratches of 1 mm or more that appeared on the coating film were identified, and the position of the base end of the linear scratch that appeared at the deepest groove position among them was read. Measurements were carried out with N = 10, and the average value was taken as the measured value. The water-in-oil emulsion compositions measured for each of N = 10 were randomly collected from different locations within the same sample. The measured values ​​are shown in Table 2.

[0087]

[0088]

[0089]

[0090]

[0091] As shown in Comparative Examples 1 to 3, when a water-in-oil emulsion composition was prepared by adding polysaccharide particles before emulsification, significant aggregation occurred. In particular, when cellulose with a low total degree of substitution and cellulose acetate 1 were used (Comparative Examples 1 and 2), aggregation was even more significant than when cellulose 2 with a relatively high total degree of substitution was used (Comparative Example 3).

[0092] On the other hand, as shown in Examples 1 to 6, when a water-in-oil emulsion composition was prepared by adding polysaccharide particles after emulsification, aggregation was significantly suppressed, i.e., dispersibility was significantly improved. In particular, as shown in Examples 1 to 3, when the temperature during mixing of the polysaccharide particles was lowered to 35°C, aggregation was further suppressed, i.e., dispersibility was further improved. Among these, when cellulose with a low total degree of substitution and cellulose acetate 1 (Examples 1 and 2), which had a significant aggregation problem (Comparative Examples 1 and 2 compared to Comparative Example 3), were used, substantially the same level of dispersibility was obtained as when cellulose 2 with a relatively high total degree of substitution was used (Example 3). In other words, when the temperature during mixing of the polysaccharide particles was lowered to 35°C, the effect of improving dispersibility was found to be significantly improved when cellulose with a low total degree of substitution and cellulose acetate 1 (Examples 1 and 2) were used.

[0093] Test Example 2 Various water-in-oil emulsion compositions shown in Table 6 were prepared. Specifically, Example 7 was prepared in the same manner as in Test Example 1 [2-1] except that the temperature during addition of cellulose acetate was 30°C, Example 8 was prepared in the same manner as in Test Example 1 [2-2], and Comparative Example 4 was prepared in the same manner as in Test Example 1 [2-3]. Note that the same cellulose acetate 1 as described in Test Example 1 was used. As in Test Example 1, appearance photographs, micrographs, and dispersibility scores (all initial) are shown in Table 6.

[0094]

[0095] As shown in Comparative Example 4, when a water-in-oil emulsion composition was prepared by adding polysaccharide particles before emulsification, significant aggregation occurred. On the other hand, as shown in Examples 7 and 8, when a water-in-oil emulsion composition was prepared by adding polysaccharide particles after emulsification, aggregation was significantly suppressed, that is, dispersibility was significantly improved. In particular, as shown in Example 7, when the temperature during mixing of the polysaccharide particles was lowered to 30°C, aggregation was further suppressed, that is, dispersibility was further improved. The trends in aggregation occurrence and dispersibility improvement in the comparative examples and examples in this Test Example 2 were the same as the trends in aggregation occurrence and dispersibility improvement in the comparative examples and examples shown in Test Example 1.

[0096] Test Example 3 Various water-in-oil emulsion compositions shown in Table 7 were prepared. Specifically, various water-in-oil emulsion compositions were prepared in the same manner as in Test Example 2, except that silica was used instead of cellulose acetate 1. As in Test Example 1, appearance photographs, micrographs, and dispersibility scores (all initial) are shown in Table 7.

[0097]

[0098] As shown in Reference Example 3, when a water-in-oil emulsion composition was prepared by adding silica particles other than polysaccharide particles before emulsification, no aggregation occurred and excellent dispersibility was observed. On the other hand, as shown in Reference Examples 1 and 2, when a water-in-oil emulsion composition was prepared by adding silica particles before emulsification, the aggregates became larger and the dispersibility became poorer. In particular, as shown in Reference Example 1, when the temperature during mixing of the silica particles was lowered to 30°C, the aggregates became even larger and the dispersibility became even poorer. Thus, the dispersibility trends in Reference Examples 3 and Reference Examples 1 and 2 in this Test Example 3 were exactly opposite to the dispersibility trends in the comparative examples and examples shown in Test Examples 1 and 2. In other words, it was confirmed that the occurrence of aggregation observed in the comparative examples of Test Examples 1 and 2 and the improved dispersibility observed in the examples of Test Examples 1 and 2 are unique issues and effects resulting from the selection of polysaccharide particles as particles.

[0099] Test Example 4 Various water-in-oil emulsion compositions shown in Table 8 were prepared. Specifically, water-in-oil emulsion compositions (Examples 9 and 10) were prepared in the same manner as in Example 2 of Test Example 1, except that magnesium sulfate or trisodium citrate was added to the aqueous phase composition containing component (I), and the balance was water. Table 8 shows micrographs and dispersibility scores after storage at 50°C for 2 weeks, 1 month, or 2 months.

[0100]

[0101] As shown in Table 8, the water-in-oil emulsion composition of Example 2 (containing neither magnesium sulfate nor trisodium citrate) retained a high dispersibility score of 8 even after storage at 50°C for 2 weeks. On the other hand, the water-in-oil emulsion compositions of Examples 9 and 10, in which magnesium sulfate or trisodium citrate was further added to the composition of Example 2, maintained an extremely high dispersibility score of 10, the same as immediately after preparation, even after storage at 50°C for 2 weeks. This indicates that the addition of magnesium sulfate or trisodium citrate further improved dispersibility.

[0102] When the water-in-oil emulsion compositions of Examples 9 and 10 were stored for a longer period of time, Example 10 fell below a score of 10 first. In other words, compared to Example 9 and Example 10, Example 9 had superior dispersibility.

[0103] Test Example 5 Various water-in-oil emulsion compositions shown in Table 9 were prepared. Specifically, they were prepared in the same manner as in [2-1] of Test Example 1. The same cellulose acetate 1 as described in Test Example 1 was used. Dispersibility scores (initial values ​​in all cases) were calculated in the same manner as in Test Example 1. The results are shown in Table 9.

[0104]

[0105] As shown in Table 9, the water-in-oil emulsion compositions of Examples 11 to 14 had extremely simple compositions and contained large amounts of water, which inherently posed a significant problem of aggregation of cellulose acetate 1. Despite this, they exhibited superior dispersibility to any of the comparative examples in the aforementioned Test Examples. Furthermore, as shown in Examples 12 to 14, the addition of a specific salt (a water-soluble salt of an acid whose average pKa value of the derived acid is -1 to 5) further improved dispersibility. This was consistent with the trends observed in Examples 9 and 10 of Test Example 4. This further improvement in dispersibility tended to decrease as the average pKa value of the derived acid increased. Therefore, the water-in-oil emulsion composition (Example 15) containing 1.3 wt. % sodium bicarbonate (whose average pKa value of the derived acid is 6.37) instead of the specific salt did not exhibit the improved dispersibility observed in Examples 12 to 14, and exhibited dispersibility similar to that of Example 11 (score 4).

Claims

1. A water-in-oil emulsion composition containing particles in an oil phase whose main component is a polysaccharide polymer selected from the group consisting of polysaccharides and polysaccharide esters, wherein the dispersibility of the particles is 130 μm or less as measured using a grind gauge.

2. The water-in-oil emulsion composition according to claim 1, wherein the polysaccharide polymer is selected from the group consisting of polysaccharides and polysaccharide esters having a total degree of substitution of more than 0 and not more than 2.

9.

3. The water-in-oil emulsion composition according to claim 1, wherein the polysaccharide polymer is selected from the group consisting of cellulose and cellulose esters.

4. The water-in-oil emulsion composition according to claim 1, wherein the polysaccharide polymer is selected from the group consisting of cellulose and cellulose esters having a total degree of substitution of more than 0 and not more than 2.

9.

5. The water-in-oil emulsion composition according to claim 1, wherein the polysaccharide polymer is selected from the group consisting of cellulose and cellulose esters having a total degree of substitution of more than 0 and not more than 2.

5.

6. The water-in-oil emulsion composition according to claim 1, wherein the polysaccharide polymer is selected from the group consisting of cellulose and cellulose esters having a total degree of substitution of more than 0 and not more than 1.

0.

7. The water-in-oil emulsion composition according to claim 1, wherein the water content in the water-in-oil emulsion composition is 20 to 70% by weight.

8. The water-in-oil emulsion composition according to claim 1, wherein the content of said particles in said water-in-oil emulsion composition is 0.5 to 15% by weight.

9. The water-in-oil emulsion composition according to claim 1, wherein the content of said particles is 1 to 50 parts by weight per 100 parts by weight of water in said water-in-oil emulsion composition.

10. The water-in-oil emulsion composition according to claim 1, further comprising a water-soluble salt of an acid having an average pKa value of -1 to 5.

11. The water-in-oil emulsion composition according to claim 10, wherein the salt is contained in an amount such that the product of the number of moles of the anion of the acid and the valence of the anion is 0.0005 moles or more per 100 g of the water-in-oil emulsion composition.

12. A cosmetic composition comprising the water-in-oil emulsion composition according to claim 1.

13. A method for producing a water-in-oil emulsion composition, comprising: step A of preparing a water-in-oil emulsion composition for a base from an oil phase composition and an aqueous phase composition; and step B of mixing the water-in-oil emulsion composition for a base with particles whose main component is a polysaccharide polymer selected from the group consisting of polysaccharides and polysaccharide esters.

14. The method according to claim 13, wherein step B is carried out at 5 to 40°C.

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