Oil droplet emulsions in water

Abstract

To provide an oil-in-water drop type emulsified product having high stability even if an oily raw material is blended in a large amount.SOLUTION: There is provided an oil-in-water drop type emulsified product which comprises (a) a water-soluble polymer containing a sugar chain, (b) a nonionic surfactant and / or an amphoteric surfactant, (c) an oily raw material and (d) water. The present invention can obtain an oil-in-water drop type emulsified product having high emulsion stability even if an oily raw material is bended in a large amount. In addition, the present invention can obtain an oil-in-water drop type emulsified product which has less viscosity reduction even if a base is blended and has high viscosity stability.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an oil-in-water emulsion that is highly stable even when a large amount of oily raw material is blended therein. [Background technology]

[0002] Emulsions are used in creams and other products in the fields of cosmetics, pharmaceuticals, food, etc. Among these emulsions, oil-in-water emulsions are often used in cosmetics because of their pleasant texture when applied to the skin.

[0003] In oil-in-water emulsions used as cosmetics, increasing the amount of oily raw material is expected to improve the emollient effect and the effect of preventing skin dryness. Furthermore, when such oil-in-water emulsions are applied to sunscreens, it is possible to suppress the precipitation of UV absorbers and stickiness caused by UV absorbers, allowing the incorporation of a larger amount of UV absorbers, or to suppress the squeaking of UV scattering agents, allowing the incorporation of a larger amount of UV scattering agents, thereby achieving the advantage of achieving a high UV protection effect.

[0004] However, generally, when a large amount of oily ingredients is blended into an oil-in-water emulsion, the amount of surfactant blended is increased to achieve emulsion stability, which poses the problem of stickiness caused by the surfactant, impairing the feel when used. On the other hand, if the amount of surfactant blended is reduced in such a case, there is the problem of the emulsion easily separating into a water layer and an oil layer. Therefore, research and development has been conducted on oil-in-water emulsions that contain a large amount of oily ingredients and have high emulsion stability. For example, Patent Document 1 discloses an oil-in-water emulsion cosmetic that contains, in addition to water and oily ingredients, phospholipids, glycerin, 1,3-butylene glycol, and a higher alcohol that is solid at 25°C. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5833810 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the oil-in-water emulsion cosmetic described in Patent Document 1 requires the inclusion of glycerin and 1,3-butylene glycol in a specific ratio and the inclusion of a solid higher alcohol, which limits the range of products to which it can be applied. Furthermore, higher alcohols can cause undesirable sensations during use, such as a braking sensation, and therefore the feel during use is unsatisfactory. In other words, even in light of this patent document, there is still no sufficient supply of oil-in-water emulsions that are highly stable, have a good feel during use, and are applicable to a wide range of products, even when they contain a large amount of oil-based ingredients. The present invention has been made to solve these problems, and aims to provide an oil-in-water emulsion that is highly stable, has a good feel during use, and is applicable to a wide range of products, even when they contain a large amount of oil-based ingredients. [Means for solving the problem]

[0007] As a result of extensive research, the present inventors have found that by combining a water-soluble polymer containing a sugar chain with a nonionic surfactant and / or an amphoteric surfactant, it is possible to produce an oil-in-water emulsion that is highly stable even when it contains a large amount of oily ingredients. Based on this finding, the present inventors have completed the following inventions.

[0008] (1) The oil-in-water emulsion of the present invention contains the following (a) to (d): (a) a water-soluble polymer containing a sugar chain; (b) nonionic surfactants and / or amphoteric surfactants; (c) oily raw materials; (d) Water.

[0009] (2) The oil-in-water emulsion according to the present invention may contain (c) an oily ingredient in a proportion of more than 27.5% by mass and less than 80% by mass relative to 100% by mass of the oil-in-water emulsion.

[0010] (3) The oil-in-water emulsion according to the present invention may contain (b) a surfactant in a mass ratio of more than 0.0016 to 0.04 per 1 part of (c) the oily raw material.

[0011] (4) The oil-in-water emulsion according to the present invention may contain (a) a water-soluble polymer in a proportion of more than 0.4% by mass and less than 4% by mass relative to 100% by mass of the oil-in-water emulsion.

[0012] (5) The oil-in-water emulsion according to the present invention may have a viscosity of 6000 mPa s or more at 25°C, measured using a single cylindrical rotational viscometer with an M3 rotor at a rotation speed of 12 rpm for a measurement time of 1 minute.

[0013] (6) The oil-in-water emulsion according to the present invention may be used in cosmetics. [Effects of the Invention]

[0014] According to the present invention, an oil-in-water emulsion having high emulsification stability can be obtained even when a large amount of oily raw material is incorporated. According to the present invention, an oil-in-water emulsion having high viscosity stability and minimal viscosity reduction even when a salt is incorporated can be obtained. Since the oil-in-water emulsion of the present invention requires only a small amount of surfactant even when a large amount of oily raw material is incorporated, it is possible to reduce stickiness caused by the surfactant, reduced water resistance of the applied emulsion, and concerns about skin irritation and safety caused by the surfactant. By incorporating a water-soluble polymer in a predetermined ratio into the oil-in-water emulsion of the present invention, it is possible to obtain an oil-in-water emulsion having low stickiness even when a large amount of oily raw material is incorporated, and having excellent spreadability, comfort on the skin, and usability.

[0015] When the oil-in-water emulsion of the present invention is applied to skin cosmetics or finishing cosmetics, a large amount of oily raw materials can be blended, making it possible to produce products with improved emollient effects and anti-drying effects for the skin.When the oil-in-water emulsion of the present invention is applied to hair cosmetics, a large amount of oily raw materials can be blended, making it possible to produce products that give hair a moist feel, manageability, and good combability after use.

[0016] When the oil-in-water emulsion of the present invention is applied to sunscreen cosmetics, it is possible to produce a product with high emulsion stability by preventing precipitation of the UV absorber even when a large amount of the UV absorber is incorporated, since it is possible to incorporate a large amount of the oil-based raw material.Similarly, it is possible to produce a product with a refreshing and pleasant feel on application and in use, since it is possible to incorporate a large amount of the oil-based raw material, even when a large amount of the UV scattering agent is incorporated, it is possible to reduce the squeaky feeling caused by the UV scattering agent. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a table showing raw materials used in the present example. [Figure 2] 1 is a table showing the composition and the evaluation results of emulsion stability for oil-in-water emulsions produced using various water-soluble polymers. [Figure 3] 1 is a table showing the composition and the evaluation results of emulsion stability for oil-in-water emulsions produced by varying the blending amount of a water-soluble polymer. [Figure 4] (I) is a table showing the evaluation items and scoring criteria of the sensory test, and (II) is a table showing the scoring results and the average scores (evaluation scores) of the five panelists (A to B). [Figure 5] 1 is a table showing the composition and the evaluation results of a sensory test for oil-in-water emulsions produced by varying the blending amount of a water-soluble polymer. [Figure 6] 1 is a table showing the composition and the evaluation results of emulsion stability for oil-in-water emulsions produced by varying the amount of surfactant blended. [Figure 7]1 is a table showing the composition and emulsion stability evaluation results of oil-in-water emulsions produced using various oily raw materials. [Figure 8] 1 is a table showing the composition and the evaluation results of emulsion stability for oil-in-water emulsions produced by varying the blending amount of oily raw material. [Figure 9] 1 is a table showing the composition, viscosity, and emulsion stability evaluation results for oil-in-water emulsions produced by varying the blending amounts of a water-soluble polymer and an oily raw material. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail below.

[0019] An oil-in-water (O / W) emulsion is one in which oil and water or an aqueous solution are mixed, with the oil dispersed in the water or aqueous solution as fine droplets. Whether an emulsion is oil-in-water or water-in-oil can be determined, for example, by sprinkling a powdered dye on the emulsion and observing how it spreads. Specifically, a powdered water-soluble dye (e.g., methylene blue) or oil-soluble dye (e.g., Sudan III) is sprinkled on the emulsion. If the dye spreads when the former is sprinkled on the emulsion but not when the latter is sprinkled on the emulsion, the emulsion can be determined to be an oil-in-water emulsion.

[0020] In the present invention, "emulsion stability" refers to the degree of change in state (mainly separation of the oil layer and the aqueous layer) when an emulsion is stored for a certain period of time. In other words, "emulsion stable," "high emulsion stability," or "good emulsion stability" means that there is no or little change in state after a certain period of time has passed, or that it takes a long time for a change in state to occur. Conversely, "no emulsion stability," "low emulsion stability," or "poor emulsion stability" means that there is a large change in state after a certain period of time has passed, or that the storage period until a change in state occurs is short. Emulsion stability can be evaluated, for example, by placing an emulsion in a sealed container, storing it at a relatively high temperature of about room temperature to 50°C for a certain period of time, and then observing the state visually or with a microscope.

[0021] In the present invention, "viscosity stability" refers to the degree of viscosity change when salt is added to an emulsion. That is, "viscosity stable," "high viscosity stability," or "good viscosity stability" means that when comparing the viscosities of an emulsion with and without salt, there is little or no difference in the viscosity values ​​between the two. Conversely, "no viscosity stability," "low viscosity stability," or "poor viscosity stability" means that there is a large difference in the viscosity values ​​between the two.

[0022] The oil-in-water emulsion of the present invention contains (a) a water-soluble polymer containing a sugar chain, (b) a nonionic surfactant and / or an amphoteric surfactant, (c) an oil-based raw material, and (d) water.

[0023] A "water-soluble polymer containing a sugar chain" refers to a molecule with a large molecular weight that is soluble in water and that contains a sugar chain or is composed solely of a sugar chain. Water-soluble polymers containing a sugar chain include nonionic, anionic, and cationic polymers, and any of these can be used in the present invention. Examples of water-soluble polymers containing a sugar chain include those that can be used in cosmetics, quasi-drugs, pharmaceuticals, and foods. Specific examples include hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl starch phosphate, guar gum, tamarind seed gum, polyquaternium-10, xanthan gum, agar, quince seed gum, locust bean gum, sclerotium gum, carrageenan, starch, hydroxypropyl cellulose, hydroxypropyl methylcellulose, and gellan gum.

[0024] The water-soluble polymer containing a sugar chain may be blended into the oil-in-water emulsion either alone or in combination. The blending amount can be appropriately set depending on the type of water-soluble polymer, the use of the emulsion, and the types and blending amounts of other raw materials such as (b), (c), and (d) above. For example, when the entire emulsion is taken as 100, the lower limit is preferably more than 0.4% by mass, more preferably 0.5% by mass or more, and even more preferably 0.6% by mass or more, 0.7% by mass or more, 0.8% by mass or more, 0.9% by mass or more, or 1.0% by mass or more, from the viewpoint of emulsion stability. Furthermore, the upper limit is preferably less than 4.0% by mass from the viewpoint of obtaining excellent spreadability, comfort on the skin, and usability, and is more preferably 3.9% by mass or less, 3.8% by mass or less, 3.7% by mass or less, 3.6% by mass or less, 3.5% by mass or less, 3.4% by mass or less, 3.3% by mass or less, 3.2% by mass or less, 3.1% by mass or less, or 3.0% by mass or less, and even more preferably 2.9% by mass or less, 2.8% by mass or less, 2.7% by mass or less, 2.6% by mass or less, 2.5% by mass or less, 2.4% by mass or less, 2.3% by mass or less, 2.2% by mass or less, 2.1% by mass or less, or 2.0% by mass or less.

[0025] In the present invention, the "nonionic surfactant" can be one that can be used in cosmetics, quasi-drugs, pharmaceuticals, foods, etc. Examples of nonionic surfactants include polyoxyethylene fatty acid esters (such as PEG-10 stearate), polyoxyethylene glycerin fatty acid esters (such as PEG-15 glyceryl stearate), polyoxyethylene sorbitan fatty acid esters (such as polysorbate 80), polyoxyethylene hydrogenated castor oil (such as PEG-60 hydrogenated castor oil), polyoxyethylene castor oil (such as PEG-30 castor oil), polyoxyethylene sorbitol tetra fatty acid esters (such as sorbeth 30 tetraoleate), glycerin fatty acid esters (such as glyceryl stearate), and sorbitan fatty acid esters. Examples of such esters include sorbitan stearate, polyglycerin fatty acid esters (such as polyglyceryl-10 stearate), sucrose fatty acid esters (such as sucrose distearate), alkyl polyglucosides (such as lauryl glucoside), polyoxyethylene cholesteryl ethers (such as cholestrol-10), polyoxyethylene phytosteryl ethers (such as PEG-20 phytosterol), polyoxyethylene alkyl ethers (such as steareth-2, steareth-4, steareth-20, steareth-21), and polyether-modified silicones (such as PEG-10 dimethicone).

[0026] In the present invention, the "amphoteric surfactant" can be one that can be used in cosmetics, quasi-drugs, pharmaceuticals, foods, etc. Examples of amphoteric surfactants include lecithin (soybean lecithin, egg yolk lecithin, soybean phospholipid, hydrogenated egg yolk lecithin, hydrogenated soybean lecithin, hydroxide lecithin, lysolecithin, etc.), sulfate ester salt type, sulfonate salt type, phosphate ester salt type, imidazoline type, betaine type, and amidoamine oxide type amphoteric surfactants. Of these, lecithin is particularly less irritating to the skin and is highly safe. Therefore, when the emulsion of the present invention is used in products such as skin care cosmetics that are intended for application to the skin or living organisms, it is preferable to use lecithin as the amphoteric surfactant.

[0027] The nonionic surfactant and amphoteric surfactant may be blended into the emulsion alone or in combination of two or more. The blending amount of these surfactants can be appropriately determined depending on the type of surfactant, the purpose of the emulsion, and the types and blending amounts of other raw materials such as (a), (c), and (d) above. However, as shown in the examples below, in the present invention, an emulsion with high emulsion stability can be obtained with a relatively small amount of surfactant, despite containing a large amount of oily raw material.

[0028] From the viewpoint of emulsion stability, the specific amount of surfactant to be added is preferably more than 0.0016 by mass relative to 1 part of the oily raw material, and more preferably 0.0017 or more, 0.0018 or more, 0.0019 or more, or 0.002 or more. Furthermore, from the viewpoint of avoiding stickiness or the like caused by the surfactant that would result in a poor feel to the touch and sensation in use, from the viewpoint of reducing skin irritation, and from the viewpoint of reducing safety concerns caused by the surfactant, the upper limit is preferably 0.08 or less in mass ratio relative to 1 of the oily raw material, more preferably 0.078 or less, 0.076 or less, 0.074 or less, 0.072 or less, 0.07 or less, 0.068 or less, 0.066 or less, 0.064 or less, 0.062 or less, or 0.06 or less, and even more preferably 0.058 or less, 0.056 or less, 0.054 or less, 0.052 or less, 0.05 or less, 0.048 or less, 0.046 or less, 0.044 or less, 0.042 or less, or 0.04 or less.

[0029] An "oily raw material" refers to a substance that dissolves in oil but is insoluble in water. In the present invention, oily raw materials that can be used in cosmetics, quasi-drugs, pharmaceuticals, foods, etc. can be used. For example, oily raw materials can be classified based on their chemical structure into oils and fats, higher fatty acids, waxes, hydrocarbons, esters, higher alcohols, silicone oils, etc., and any of these can be used. In addition, oily raw materials that are liquid, solid, or semi-solid (e.g., paste) at room temperature can also be used. In addition, oily raw materials that function as ultraviolet absorbers can also be used.

[0030] For example, examples of fats and oils include horse oil, coconut oil, shea butter, rice germ oil, olive fruit oil, camellia oil, grape seed oil, macadamia nut oil, castor oil, apricot oil, and triethylhexanoin. Examples of higher fatty acids include coconut oil fatty acid, behenic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and isostearic acid. Examples of waxes include jojoba seed oil, carnauba wax, candelilla wax, beeswax, and lanolin. Examples of hydrocarbons include olefin-based hydrocarbons such as hydrogenated polyisobutene, isododecane, and tetradecene, mineral oil (liquid paraffin), paraffin, petrolatum, ceresin, microcrystalline wax, and squalane. Examples of esters include olefin-based hydrocarbons such as hydrogenated polyisobutene, isododecane, and tetradecene, mineral oil (liquid paraffin), paraffin, petrolatum, ceresin, microcrystalline wax, and squalane. Examples of the surfactants include stearyl isostearate, cetyl palmitate, ethylhexyl palmitate, isopropyl myristate, 2-octyldodecyl myristate, cetyl 2-ethylhexanoate, and diisostearyl malate. Examples of higher alcohols include cetyl alcohol, stearyl alcohol, isostearyl alcohol, and 2-octyldodecanol. Examples of silicone oils include straight silicone oils such as dimethicone, amino-modified silicone oils such as amodimethicone, alkyl-modified silicone oils such as stearyl dimethicone, polyether-modified silicone oils such as PEG-12 dimethicone, phenyl-modified silicones such as methylphenylpolysiloxane, and cyclic polysiloxanes such as cyclopentasiloxane. Examples of UV absorbers include ethylhexyl methoxycinnamate, octocrylene, polysilicone-15, homosalate, and ethylhexyl salicylate.

[0031] The oily ingredient may be blended into the emulsion alone or in combination of two or more. The blending amount of the oily ingredient can be appropriately set depending on the use of the emulsion, etc., but from the viewpoint of emulsion stability, when the entire emulsion is taken as 100, the lower limit is preferably more than 27.5% by mass, more preferably 28% by mass or more, 28.5% by mass or more, 29% by mass or more, 29.5% by mass or more, or 30% by mass or more, and even more preferably 31% by mass or more, 32% by mass or more, 33% by mass or more, 34% by mass or more, 35% by mass or more, 36% by mass or more, 37% by mass or more, 38% by mass or more, 39% by mass or more, or 40% by mass or more. The upper limit is preferably less than 80% by mass, more preferably 79.5% by mass or less or 79% by mass or less, and even more preferably 77.5% by mass or less, 77% by mass or less, 76.5% by mass or less, 76% by mass or less, 75.5% by mass or less, or 75% by mass or less.

[0032] The viscosity of the oil-in-water emulsion according to the present invention is preferably 6000 mPa·s or more when measured under the conditions described below. Such a viscosity allows for high emulsion stability, as will be shown in the examples described below. The viscosity of the emulsion can be measured according to "Japanese Pharmacopoeia, 17th Edition (Ministry of Health, Labour and Welfare Notification No. 64, March 7, 2016) 2.53 Viscosity Measurement Method, Method 2, Rotational Viscometer Method." Viscosity measurement conditions: Apparatus: Commercially available single-cylindrical rotational viscometer (Brookfield type viscometer), temperature: 25°C, measurement time: 1 minute, rotor: M3, rotation speed: 12 rpm.

[0033] The viscosity of the oil-in-water emulsion can be adjusted by the amount of water-soluble polymer and / or oil-based raw material. That is, a second preferred amount of the water-soluble polymer containing a sugar chain can be an amount at which the viscosity of the oil-in-water emulsion measured under the above conditions is 6000 mPa s or higher. Similarly, a second preferred amount of the oil-based raw material can be an amount at which the viscosity of the oil-in-water emulsion measured under the above conditions is 6000 mPa s or higher.

[0034] The emulsion of the present invention can be produced by mixing the above (a) to (d) in a conventional manner. More specifically, as shown in the examples described below, first, (a) a water-soluble polymer containing a sugar chain is dispersed in a dispersion medium (such as water or 1,3-butylene glycol) to obtain dispersion A. Next, (c) a nonionic surfactant and / or an amphoteric surfactant is dissolved in an oil-based raw material while heating as necessary, depending on the type and form of the raw material. This is then added to (d) water and dispersed while heating as necessary to obtain dispersion B. Next, an example of a production procedure is to add dispersion A to dispersion B while heating and stirring as necessary, and mix them.

[0035] The form of the oil-in-water emulsion of the present invention is not particularly limited, but may be, for example, liquid, cream, or gel.

[0036] The oil-in-water emulsion of the present invention may contain other ingredients besides the ingredients (a) to (d) above, provided that the effects of the present invention are not impaired. Examples of such other ingredients include solvents or dispersion media, polyhydric alcohols such as ethanol, glycerin, 1,3-butylene glycol, propylene glycol, dipropylene glycol, and pentylene glycol, sugars such as sorbitol, cationic surfactants, pH adjusters, colorants, animal and plant extracts, vitamins and their derivatives, whitening agents, anti-inflammatory agents, chelating agents, inorganic or organic salts, solubilizers, preservatives, disinfectants, moisturizers, antioxidants, humectants, UV absorbers, UV scattering agents, thickeners, fragrances, cationic polymers, refreshing agents, and cooling agents. These other ingredients can be added as needed during or after emulsion preparation.

[0037] The oil-in-water emulsion according to the present invention can be used in cosmetics, foods, pharmaceuticals, quasi-drugs, etc. Examples of cosmetics include those containing a large amount of oily ingredients, such as cosmetic liquids (moisturizing liquids, beauty serums, etc.), creams, emulsions, sunscreens, sunscreens, cleansers, packs (rinse-off packs), massage products, body rinses, liquid foundations, hair styling products (hair creams, etc.), hair care products (hair treatments, hair packs, hair conditioners, etc.), scalp products (scalp treatments, etc.), hair coloring products (color rinses, hair manicures, etc.), and hair rinses. When used in these cosmetics, the above (a), (b), and (c) in the oil-in-water emulsion of the present invention are set to those suitable for the intended use of the product and used as a base, and fragrances, quality-preserving ingredients (preservatives, antioxidants, etc.), cosmetic agents (ultraviolet absorbers, vitamins, plant extracts, whitening agents, etc.), ionic surfactants, etc. can be added depending on the intended use of the product to produce the cosmetics.

[0038] The present invention will be described below based on examples. Note that the technical scope of the present invention is not limited to the features shown in these examples. In the examples, "%" represents % by mass ((w / w)%) unless otherwise specified. [Example]

[0039] <Test Method> Unless otherwise specified, the tests were carried out according to the following methods. (1) Raw materials used An oil-in-water emulsion was produced using the raw materials shown in Figure 1 (all commercially available products).

[0040] (2) Production of oil-in-water emulsion An oil-in-water emulsion was produced according to the following steps 1 to 6. 1. Dispersion A was obtained by dispersing a water-soluble polymer in a dispersion medium (a portion of purified water, approximately 4% of the total emulsion). 2. Phenoxyethanol was added to the remaining purified water to a concentration of 0.35% and pentylene glycol to a concentration of 1% (both final concentrations in the emulsion). 3. The surfactant was added to the oily raw material and dissolved while heating to about 65°C to about 80°C. 4. While heating to about 65°C to about 80°C, the oily raw material in 3 was added to the purified water in 2 and stirred to disperse, thereby obtaining dispersion B. 5. Dispersion A was added to Dispersion B while stirring. After the addition was complete, the mixture was stirred for 10 minutes. 6. Allow to cool to room temperature, completing the manufacturing process.

[0041] (3) Evaluation of emulsion stability The emulsion was placed in a transparent, airtight container and left in an environment at 40°C or 50°C for one week to one month. Alternatively, it was left in an environment where the temperature changed from -10°C to 40°C in a 24-hour cycle (temperature change cycle) for one month. After one week and one month, the appearance was visually observed and evaluated according to the following criteria. ○: Remains as one layer (no or very little change in state). △: Tendency to separate into two layers is observed. ×: Separated into two layers. -: Not rated.

[0042] <Example 1> Examination of types of water-soluble polymers (1) Evaluation of emulsion stability Oil-in-water emulsions (Nos. 1 to 8) were prepared using various water-soluble polymers, and their emulsion stability was evaluated. The water-soluble polymers used were hydroxyethyl cellulose, hydroxypropyl starch phosphate, guar gum (galactomannan), and tamarind seed gum, which are nonionic water-soluble polymers containing sugar chains; polyquaternium-10 (O-(2-hydroxy-3-(trimethylammonio)propyl)hydroxyethylcellulose chloride), which is a cationic water-soluble polymer containing sugar chains; xanthan gum and agar, which are anionic water-soluble polymers containing sugar chains; and hydrolyzed collagen, which is a protein or peptide. For guar gum, tamarind seed gum, polyquaternium-10, xanthan gum, and agar, purified water and / or 1,3-butylene glycol were used as the dispersion medium in an amount equivalent to approximately 4% by mass of the total emulsion. The compositions and evaluation results of Nos. 1 to 8 are shown in Figure 2. Steareth-2 and steareth-21 were used in combination at a blending ratio that gave an HLB (Hydrophilic-Lipophilic Balance) of approximately 10.

[0043] As shown in Figure 2, No. 8 (hydrolyzed collagen) separated after one week of storage at 40°C, whereas Nos. 1 to 7 (nonionic, cationic, or anionic water-soluble polymers containing sugar chains) were all stable for more than one week at 40°C and for more than one month under temperature cycling. Furthermore, No. 1 and Nos. 3 to 6 were stable for more than one month at 50°C. These results demonstrate that the use of water-soluble polymers containing sugar chains can impart high emulsion stability to oil-in-water emulsions. Furthermore, it was also demonstrated that water-soluble polymers containing sugar chains, whether nonionic, cationic, or anionic, can impart high emulsion stability to oil-in-water emulsions.

[0044] (2) Evaluation of viscosity stability Oil-in-water emulsions Nos. 1 and 2 were prepared using either hydroxyethyl cellulose (a nonionic water-soluble polymer containing sugar chains) or carbomer (anionic water-soluble polymer containing no sugar chains) as the water-soluble polymer. Subsequently, sodium chloride (NaCl) was added to the emulsion to a final concentration of 0.5% or 1%. After mixing, the viscosity was measured. The viscosity measurement conditions were as follows: VISCOMETER TVB-10M (Toki Sangyo Co., Ltd.), 25°C, 1 minute, rotor M3 (for No. 1 measurement) or M4 (for No. 2 measurement), and 3 rpm. The viscosity of the sample without added NaCl (0% NaCl concentration) was set to 100%, and the viscosities of the samples with 0.5% and 1% NaCl concentrations were converted to percentages, which were used as the viscosity change rate. Table 1 shows the compositions of Nos. 1 and 2 (Steareth-2 and Steareth-21 were used in a combination ratio that resulted in an HLB of approximately 10), the viscosity measurement results (units: millipascal seconds (mPa·s) (centipoise; cps)), and the viscosity change rate (in parentheses). [Table 1]

[0045] As shown in Table 1, the viscosity change rate of No. 2 (carbomer) was 32% when the NaCl concentration was 0.5% and 23% when the NaCl concentration was 1.0%, showing a significant decrease in viscosity as the NaCl concentration increased. In contrast, the viscosity change rate of No. 1 (hydroxyethyl cellulose) was 96% when the NaCl concentration was 0.5% and 103% when the NaCl concentration was 1.0%, showing a nearly constant viscosity regardless of the NaCl concentration. These results demonstrate that by using a water-soluble polymer containing a sugar chain, it is possible to obtain an oil-in-water emulsion with minimal viscosity change and high viscosity stability even when salt is added.

[0046] Example 2: Study of the amount and viscosity of water-soluble polymer (1) Evaluation of emulsion stability Oil-in-water emulsions Nos. 1 to 6 were produced by varying the amount of water-soluble polymer (hydroxyethyl cellulose) from 0.1% to 1.0%, and the emulsion stability was evaluated. The compositions of Nos. 1 to 6 (steareth-2 and steareth-21 were used in combination at a ratio that gave an HLB of approximately 10) and the evaluation results are shown in Figure 3.

[0047] As shown in Figure 3, Nos. 5 (hydroxyethyl cellulose 0.5%) to 6 (hydroxyethyl cellulose 1.0%) were stable for more than one week at 50°C and for more than one month under temperature cycles, and No. 6 (hydroxyethyl cellulose 1%) was stable for more than one month at 50°C. These results revealed that, from the perspective of obtaining high emulsion stability, the amount of water-soluble polymer blended is preferably more than 0.4%, more preferably 0.5% or more, and even more preferably 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, or 1.0% or more.

[0048] (2) Sensory evaluation Oil-in-water emulsions Nos. 1 to 7 were prepared by varying the amount of water-soluble polymer (hydroxyethyl cellulose) from 0.5% to 6.0%, and sensory tests were conducted. Specifically, five panelists (A to B) rated the emulsions on a 5-point scale (absolute rating) from 1 to 5 for "ease of spreadability," "skin compatibility," and "usability (comfort)" when applying and blending the emulsions to the skin. The average of the scores given by all panelists for each sample was calculated and rounded to the nearest tenth to obtain the score. Next, the average scores for the three evaluation items were calculated for each sample, and an overall evaluation was conducted based on the following criteria. The scoring criteria and the results of the panelists' ratings are shown in Figure 4, and the compositions of Nos. 1 to 7 (steareth-2 and steareth-21 were used in combination in a ratio that resulted in an HLB of approximately 10), the scores, and the overall evaluation are shown in Figure 5. <<Criteria for overall evaluation>> ◎: The average score for the three items is 3.0 or higher ○: The average score for the three items is 2.5 or more and less than 3.0 △: The average score for the three items is 2.0 or more but less than 2.5 ×: The average score for the three items is less than 2.0

[0049] As shown in Figures 4 and 5, the overall evaluation was ⊚ for No. 1 (hydroxyethyl cellulose 0.5%) to No. 3 (hydroxyethyl cellulose 2.0%), and ○ for No. 4 (hydroxyethyl cellulose 3.0%). These results reveal that, from the viewpoint of obtaining excellent spreadability, comfort on the skin, and usability, the blending amount of water-soluble polymer is preferably less than 4.0%, more preferably 3.9% or less, 3.8% or less, 3.7% or less, 3.6% or less, 3.5% or less, 3.4% or less, 3.3% or less, 3.2% or less, 3.1% or less, or 3.0% or less, and even more preferably 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, 2.1% or less, or 2.0% or less.

[0050] Example 3: Examination of surfactant types (1) Comparison of nonionic surfactants and anionic surfactants Oil-in-water emulsions Nos. 1 and 2 were produced using steareth-2 and steareth-21 (nonionic surfactants) (used in combination in a ratio giving an HLB of approximately 10) or sodium lauroyl aspartate (anionic surfactant) as the surfactant, and the emulsion stability was evaluated. The compositions of Nos. 1 and 2 and the evaluation results are shown in Table 2. [Table 2]

[0051] As shown in Table 2, No. 2 (sodium lauroyl aspartate) showed a tendency to separate when stored at 40°C and 50°C for one week, whereas No. 1 (steareth-2 and steareth-21) was stable for more than one month at 50°C and under temperature cycling. These results demonstrate that the use of nonionic surfactants can impart high emulsion stability to oil-in-water emulsions.

[0052] (2) Comparison of nonionic surfactants and amphoteric surfactants Oil-in-water emulsions Nos. 1 and 2 were produced using steareth-2 and steareth-21 (nonionic surfactants) (used in combination in a ratio giving an HLB of approximately 10) or hydrogenated lecithin (amphoteric surfactant) as surfactants, and the emulsion stability was evaluated. The compositions of Nos. 1 and 2 and the evaluation results are shown in Table 3. [Table 3]

[0053] As shown in Table 3, both No. 1 (steareth-2 and steareth-21) and No. 2 (hydrogenated lecithin) were stable for more than one week at 50°C and for more than one month under temperature cycling. These results demonstrate that the use of nonionic or amphoteric surfactants can impart high emulsion stability to oil-in-water emulsions.

[0054] (3) HLB considerations Oil-in-water emulsions Nos. 1 and 2 were produced using steareth-2 and steareth-21 as surfactants, and their emulsion stability was evaluated. The mass ratio of the two was steareth-2:steareth-21 = 1.04:0.96 (a blending ratio that results in an HLB of approximately 10) for No. 1, and 0.09:1.91 (a blending ratio that results in an HLB of approximately 15) for No. 2. The required HLB for the oil-in-water emulsion of mineral oil used as the oil-based raw material is approximately 10. The compositions and evaluation results of Nos. 1 and 2 are shown in Table 4. [Table 4]

[0055] As shown in Table 4, both No. 1 (HLB approximately 10) and No. 2 (HLB approximately 15) were stable for more than one month at 50°C and under temperature cycles. This indicates that even when a surfactant with a HLB value that does not match the required HLB of the oil-based raw material (No. 2) is used, high emulsion stability can be imparted to the oil-in-water emulsion. These results demonstrate that the present invention can impart high emulsion stability to oil-in-water emulsions regardless of the type of nonionic surfactant or amphoteric surfactant.

[0056] Example 4: Examination of surfactant blending amount The amount of surfactants (steareth-2 and steareth-21) (used in combination at a ratio giving an HLB of approximately 10) was varied by mass ratio from 0.0002 to 0.01 per 1 part of the oily raw material to produce oil-in-water emulsions Nos. 1 to 6, and the emulsion stability was evaluated. The compositions and evaluation results of Nos. 1 to 6 are shown in Figure 6.

[0057] As shown in Figure 6, No. 5 (oil-based raw material: surfactant = 1:0.002) to No. 6 (oil-based raw material: surfactant = 1:0.01) were stable for more than one month at 50°C and under temperature change cycles. These results revealed that, from the perspective of obtaining high emulsion stability, the amount of surfactant blended is preferably more than 0.0016 parts by mass per 1 part of oil-based raw material, and more preferably 0.0017 or more, 0.0018 or more, 0.0019 or more, or 0.002 or more.

[0058] <Example 5> Examination of types of oil-based raw materials Oil-in-water emulsions Nos. 1 to 7 were produced using various oil-based raw materials, and emulsion stability was evaluated. The oil-based raw materials used were mineral oil (liquid paraffin) and petrolatum as hydrocarbons, ethylhexyl palmitate (2-ethylhexyl palmitate) as esters, dimethicone (methylpolysiloxane) as silicone oils, olive fruit oil as fats and oils, and jojoba seed oil and beeswax as waxes. The compositions of Nos. 1 to 7 (steareth-2 and steareth-21 were used in combination in a ratio that resulted in an HLB of approximately 7 to 10) and the evaluation results are shown in Figure 7.

[0059] As shown in Figure 7, all of Nos. 1 to 7 were stable for more than one week at 50°C. Furthermore, Nos. 1 to 6 were stable for more than one month at 50°C and under temperature change cycles. These results demonstrate that the present invention can produce oil-in-water emulsions with high emulsion stability, regardless of the type of oil-based raw material.

[0060] Example 6: Examination of the blending amount of oil-based raw materials Oil-in-water emulsions No. 1 to 11 were produced by varying the blending amount of oily raw material (mineral oil) from 10% to 80%, and the emulsion stability was evaluated. The blending amount of surfactant (steareth-2 and steareth-21 used in combination in a blending ratio that gave an HLB of approximately 10) was set to a mass ratio of 0.04 to 1 part of oily raw material. The compositions and evaluation results of Nos. 1 to 11 are shown in Figure 8.

[0061] As shown in Figure 8, No. 5 (30% mineral oil) was stable for more than a week at 40°C and for more than a month under temperature cycling. Additionally, Nos. 6 (40% mineral oil) to 10 (79% mineral oil) were all stable for more than a month under temperature cycling at 50°C.

[0062] From these results, it was revealed that the lower limit of the amount of oil-based raw material blended is preferably more than 27.5% from the viewpoint of obtaining high emulsion stability, more preferably 28% or more, 28.5% or more, 29% or more, 29.5% or more, or 30% or more, and even more preferably 31% or more, 32% or more, 33% or more, 34% or more, 35% or more, 36% or more, 37% or more, 38% or more, 39% or more, or 40% or more. Furthermore, it was revealed that the upper limit of the amount of oil-based raw material blended is preferably less than 80% from the viewpoint of obtaining high emulsion stability, and more preferably 79.9% or less, 79.8% or less, 79.7% or less, 79.6% or less, 79.5% or less, 79.4% or less, 79.3% or less, 79.2% or less, 79.1% or less, or 79% or less.

[0063] Example 7: Study on viscosity of oil-in-water emulsion Oil-in-water emulsions Nos. 1 to 3 were prepared by varying the amount of water-soluble polymer (hydroxyethyl cellulose) from 0.3% to 0.5%. Oil-in-water emulsions Nos. 4 to 6 were prepared by varying the amount of oil-based raw material (mineral oil) from 27.5% to 50%. The viscosity of these emulsions was measured using the method described in Example 1(2). However, the rotation speed was changed from 3 rpm to 12 rpm. The emulsion stability was evaluated at 40°C for one week and after one month of temperature cycling. The compositions of emulsions Nos. 1 to 6 (steareth-2 and steareth-21 were used in combination at a ratio that resulted in an HLB of approximately 10) and the evaluation results are shown in Figure 9.

[0064] As shown in Figure 9, Nos. 1, 2, and 4 had viscosities of 3470 mPa·s, 5120 mPa·s, and 5450 mPa·s, respectively, and exhibited low emulsion stability. In contrast, Nos. 3, 5, and 6 had viscosities of 6870 mPa·s, 6790 mPa·s, and 7530 mPa·s, respectively, and exhibited high emulsion stability. This indicates that an oil-in-water emulsion with a viscosity of 6000 mPa·s exhibits high emulsion stability.

[0065] These results revealed that, from the perspective of obtaining high emulsion stability, the viscosity of the oil-in-water emulsion should preferably be 6000 mPa s or higher, as measured at 25°C using a single-cylindrical rotational viscometer with an M3 rotor at 12 rpm for 1 minute. Furthermore, from the perspective of obtaining high emulsion stability, it was revealed that the water-soluble polymer containing a sugar chain and / or oil-based raw material should preferably be blended in an amount such that the viscosity of the oil-in-water emulsion measured under these conditions is 6000 mPa s or higher.

Claims

1. The following (a) to (d): (a) a water-soluble polymer containing a sugar chain; (b) at least one nonionic surfactant and / or amphoteric surfactant selected from the group consisting of polyoxyethylene fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene hydrogenated castor oil, glycerin fatty acid esters, sorbitan fatty acid esters, polyglycerin fatty acid esters, alkyl polyglucosides, polyoxyethylene cholesteryl ethers, polyoxyethylene phytosteryl ethers, polyoxyethylene alkyl ethers, polyether-modified silicones, and hydrogenated lecithins; (c) at least one oily raw material selected from the group consisting of hydrocarbons, esters, silicone oils, fats and oils, and waxes; (d) Water Contains The (a) water-soluble polymer is contained in an amount of more than 0.4% by mass and less than 4% by mass relative to 100% by mass of the oil-in-water emulsion, The (c) oily raw material is contained in an amount of more than 27.5% by mass and less than 80% by mass relative to 100% by mass of the oil-in-water emulsion, The oil-based raw material contains a nonionic surfactant and / or an amphoteric surfactant in a mass ratio of more than 0.0016 to 0.04, The viscosity at 25°C measured using a single cylindrical rotational viscometer with an M3 rotor at a rotation speed of 12 rpm for a measurement time of 1 minute is 6000 mPa·s or more. Oil-in-water emulsion (but does not contain higher alcohol) (excluding solids).

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

3. (a) a step of adding a water-soluble polymer containing a sugar chain to a dispersion medium to obtain a dispersion A; (b) a step of dissolving a nonionic surfactant and / or an amphoteric surfactant in (c) at least one oily raw material selected from the group consisting of hydrocarbons, esters, silicone oils, fats and oils, and waxes, and (d) adding the resulting solution to water to obtain a dispersion B; a step of adding the dispersion A to the dispersion B and mixing them to obtain an oil-in-water emulsion; Including, the oil-in-water emulsion contains the water-soluble polymer (a) in an amount of more than 0.4% by mass and less than 4% by mass relative to 100% by mass of the oil-in-water emulsion, the oil-in-water emulsion contains the oily raw material (c) in an amount of more than 27.5% by mass and less than 80% by mass relative to 100% by mass of the oil-in-water emulsion, The oil-in-water emulsion contains a nonionic surfactant and / or an amphoteric surfactant in a mass ratio of more than 0.0016 to 0.04 per 1 of the oil-based raw material. A method for producing an oil-in-water emulsion (not containing higher alcohol) (excluding solids).

4. The nonionic surfactant and / or amphoteric surfactant is at least one selected from the group consisting of polyoxyethylene fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene hydrogenated castor oil, glycerin fatty acid esters, sorbitan fatty acid esters, polyglycerin fatty acid esters, alkyl polyglucosides, polyoxyethylene cholesteryl ethers, polyoxyethylene phytosteryl ethers, polyoxyethylene alkyl ethers, polyether-modified silicones, and hydrogenated lecithins; The method according to claim 3 .

Images