Surface-treated metal oxides and dispersions containing them, cosmetics

Abstract

We provide metal oxides with excellent hydrophobicity and a surface treatment that allows for global use. [Solution] A surface-treated metal oxide in which a metal oxide has been surface-treated with dimethylpolysiloxane, wherein the dimethylpolysiloxane has a kinematic viscosity of 50 to 500 mm at 25°C. 2 The surface-treated metal oxide is characterized by having a coefficient of / s and an oil absorption rate of 20 ml / 100 g or less.

Description

[Technical Field]

[0001] This invention relates to surface-treated metal oxides and dispersions and cosmetics containing them. [Background technology]

[0002] Metal oxides such as titanium dioxide and zinc oxide are used in cosmetics such as sunscreens and foundations due to their properties. Since most of these are hydrophilic, it is common practice to treat their surface with organic compounds to impart lipophilicity when incorporating them into cosmetics, thereby improving their feel and dispersibility with oil. For example, when using zinc oxide in cosmetics, it is common practice to treat it with silicone such as methylhydrogenpolysiloxane or triethoxycaprylylsilane, and the use of metal oxide fine particles such as zinc oxide coated with polysiloxane in cosmetics has been disclosed (see Patent Documents 1 and 2). [Prior art documents] [Non-patent literature]

[0003] [Patent Document 1] International Publication No. 2024 / 080367 [Patent Document 2] Japanese Patent Publication No. 2018-12679 [Overview of the project] [Problems that the invention aims to solve]

[0004] As mentioned above, metal oxides such as titanium dioxide and zinc oxide, surface-treated with organic compounds such as methylhydrogenpolysiloxane and triethoxycaprylylsilane, are widely used as raw materials for cosmetics. However, both methylhydrogenpolysiloxane and triethoxycaprylylsilane have restrictions on their use in some countries. Dimethylpolysiloxane is a surface treatment agent that can be used globally without restrictions, but it has the problem of not being sufficiently hydrophobic. If the hydrophobicity is not sufficient, the viscosity of the cosmetic will not stabilize over time, resulting in problems such as thickening or thinning of the viscosity.

[0005] In view of the above situation, the present invention aims to provide a metal oxide with excellent hydrophobicity and a surface treatment that can be used globally. [Means for solving the problem]

[0006] The inventors investigated metal oxides with excellent hydrophobicity and a surface treatment that can be used globally, and found that the surface treatment agent has a kinematic viscosity of 50 to 500 mm at 25°C. 2 We discovered that a surface-treated metal oxide using dimethylpolysiloxane of 20 ml / 100 g or less exhibits excellent hydrophobicity and can be used globally, thus completing the present invention.

[0007] In other words, the present invention is as follows. [1] A surface-treated metal oxide in which a metal oxide has been surface-treated with dimethylpolysiloxane, wherein the dimethylpolysiloxane has a kinematic viscosity of 50 to 500 mm at 25°C. 2 / s, The surface-treated metal oxide is characterized by having an oil absorption capacity of 20 ml / 100 g or less.

[0008] [2] The surface-treated metal oxide according to [1], characterized in that the amount of surface treatment with dimethylpolysiloxane is 4 to 15% by mass relative to 100% by mass of the metal oxide.

[0009] [3][1] or a dispersion obtained by dispersing the surface-treated metal oxide according to [2] in a solvent.

[0010] [4] The dispersion according to [3], wherein the proportion of the surface-treated metal oxide in the dispersion is 40% by mass or more.

[0011] [5] A cosmetic characterized by containing the surface-treated metal oxide according to [1] or [2].

[0012] [6] A cosmetic characterized by containing the dispersion according to [3] or [4]. [Effect of the Invention]

[0013] The surface-treated metal oxide of the present invention is surface-treated with dimethylpolysiloxane that can be used globally and has excellent hydrophobicity, so it can be suitably used as a raw material for cosmetics. [Brief Description of the Drawings]

[0014] [Figure 1] It is a figure showing the results of evaluating the optical properties (UV shielding property) of the powders of Example 1, 2 and Comparative Examples 1 to 3. [Figure 2] It is a figure showing the results of evaluating the optical properties (transparency) of the powders of Example 1, 2 and Comparative Examples 1 to 3. [Modes for Carrying Out the Invention]

[0015] Hereinafter, the preferred embodiments of the present invention will be specifically described. However, the present invention is not limited to the following description, and can be appropriately changed and applied within the scope of not changing the gist of the present invention.

[0016] 1. Surface-treated metal oxide The surface-treated metal oxide of the present invention has a kinematic viscosity at 25°C of 50 to 500 mm 2It is surface-treated with dimethylpolysiloxane having a viscosity of / s, and is characterized in that the oil absorption amount is 20 ml / 100 g or less. The surface-treated metal oxide having an oil absorption amount of 20 ml / 100 g or less can be said to have good compatibility with oil agents and sufficient hydrophobicity. The oil absorption amount of the surface-treated metal oxide is preferably 19 ml / 100 g or less, more preferably 17 ml / 100 g or less. Also, although there is no particular lower limit for the oil absorption amount, the oil absorption amount of the surface-treated metal oxide is 5 ml / 100 g or more. The oil absorption amount of the surface-treated metal oxide can be measured by the method described in the examples below.

[0017] The dimethylpolysiloxane used for the surface treatment of the above surface-treated metal oxide may have a kinematic viscosity at 25 °C of 50 to 500 mm 2 / s, but those having a kinematic viscosity at 25 °C of 50 to 350 mm 2 / s are preferred. More preferably, the kinematic viscosity at 25 °C is 75 to 200 mm 2 / s. The kinematic viscosity of dimethylpolysiloxane at 25 °C is calculated by measuring the viscosity and the efflux time at a specific temperature and calculating the kinematic viscosity based on that time. However, when using a commercially available product as dimethylpolysiloxane, if the manufacturer publishes the kinematic viscosity at 25 °C, that value is adopted.

[0018] In the above surface-treated metal oxide, the surface treatment amount (coating amount) with dimethylpolysiloxane is not particularly limited, but is preferably 4 to 15% by mass based on 100% by mass of the metal oxide to be subjected to the surface treatment. With such a surface treatment amount, the surface of the metal oxide can be more sufficiently hydrophobized. The surface treatment amount with dimethylpolysiloxane is more preferably 5 to 13% by mass, and even more preferably 5 to 10% by mass, based on 100% by mass of the metal oxide. The coating amount of the metal oxide surface with dimethylpolysiloxane can be calculated by the method described in the examples below.

[0019] The surface-treated metal oxide of the present invention is preferably an oxide of any one of titanium, zinc, silicon, and cerium. These metal oxides are suitable as metal oxides used in cosmetic applications. More preferably, it is titanium oxide or zinc oxide.

[0020] The specific surface area of the above surface-treated metal oxide is preferably 5 to 100 m 2 / g. Such a specific surface area can be more preferably used for cosmetic applications and the like. The specific surface area of the surface-treated metal oxide is more preferably 10 to 80 m 2 / g, and even more preferably 15 to 70 m 2 / g. The specific surface area of the surface-treated metal oxide can be measured by the method described in the examples below.

[0021] The above surface-treated metal oxide preferably has an average primary particle diameter of 1 to 100 nm. Such a specific surface area can be more preferably used for cosmetic applications and the like. The average primary particle diameter of the surface-treated metal oxide is more preferably 5 to 80 nm, and even more preferably 10 to 60 nm. The average primary particle diameter of the surface-treated metal oxide can be measured by the method described in the examples below.

[0022] When the above surface-treated metal oxide is dried at 105°C for 1 hour or more, the ratio of the weight difference before and after drying (weight loss on drying) to the weight before drying is preferably 10% or less. Such a small weight loss on drying results in a surface-treated metal oxide with a reduced amount of moisture on the particle surface and the like. This is because when incorporated into cosmetics, the contained moisture may have an adverse effect on other cosmetic components. This ratio is more preferably 8% or less, and even more preferably 5% or less.

[0023] The above-mentioned surface-treated metal oxide preferably exhibits a weight loss on ignition of 10% or less when heated at 500°C for 1 hour or more, where the weight difference before and after ignition is 10% or less compared to the weight before ignition. Such a low weight loss on ignition indicates high thermal stability. This percentage is more preferably 8% or less, and even more preferably 5% or less.

[0024] 2. Method for producing surface-treated metal oxides The method for producing the surface-treated metal oxide of the present invention is not particularly limited, but the metal oxide and the kinematic viscosity at 25°C are 50 to 500 mm². 2 A manufacturing method comprising a mixing step of mixing dimethylpolysiloxane at 0.5 / s with water, and a drying step of drying the mixture obtained in the mixing step, can be suitably used. By adding water when mixing the metal oxide and dimethylpolysiloxane in this way, the metal oxide and dimethylpolysiloxane can be mixed uniformly, and a surface-treated metal oxide can be obtained in which the metal oxide surface is uniformly treated with dimethylpolysiloxane, has sufficient hydrophobicity, and low oil absorption.

[0025] The kinematic viscosity at 25°C used in the above mixing process is 50-500 mm². 2 The proportion of dimethylpolysiloxane in / s is preferably 4 to 15% by mass relative to 100% by mass of the metal oxide. By using dimethylpolysiloxane in this proportion, the surface of the metal oxide can be sufficiently surface-treated. More preferably, the proportion of dimethylpolysiloxane is 5 to 13% by mass relative to 100% by mass of the metal oxide, and even more preferably, it is 5 to 10% by mass relative to 100% by mass of the metal oxide.

[0026] The proportion of water used in the above mixing step is preferably 1 to 20% by mass per 100% by mass of the metal oxide. Using water in this proportion allows the metal oxide to be sufficiently moistened and uniformly mixed with dimethylpolysiloxane, and because there is no excess water, the drying step time can also be shortened. More preferably, the proportion of water is 2 to 17% by mass per 100% by mass of the metal oxide, and even more preferably, 3 to 15% by mass per 100% by mass of the metal oxide.

[0027] In the above mixing process, there are no particular restrictions on the mixing order when mixing the metal oxide, dimethylpolysiloxane, and water. However, it is preferable to add and mix the water after mixing the metal oxide and dimethylpolysiloxane. This allows the treatment agent to treat the metal oxide powder more uniformly.

[0028] The mixing method in the above mixing process is not particularly limited, but examples include mechanical mixing using a stirrer, Henschel mixer, homomixer, homogenizer, etc.

[0029] The time for the above mixing step is not particularly limited as long as the metal oxide, dimethylpolysiloxane, and water are thoroughly mixed, but considering thorough mixing and manufacturing efficiency, it is preferably 1 to 90 minutes. More preferably, it is 5 to 60 minutes, and even more preferably, 5 to 50 minutes.

[0030] The above mixing step may be carried out while heating. The heating temperature is preferably 30 to 200°C, more preferably 50 to 150°C, and even more preferably 70 to 150°C.

[0031] The above drying process may be carried out with or without heating. When heating, the heating temperature can be set between 100 and 500°C. The drying time is not particularly limited as long as the mixture obtained in the mixing step is sufficiently dried, but it can be carried out in 10 minutes to 6 hours.

[0032] The drying equipment used in the above drying process is not particularly limited, but examples include box dryers, vibrating dryers, vacuum dryers, and spray dryers.

[0033] The metal oxide used in the above-described method for producing surface-treated metal oxides preferably has an average primary particle diameter of 1 to 100 nm. Using such particle sizes results in a surface-treated metal oxide that is suitable for cosmetic applications. More preferably, the metal oxide has an average primary particle diameter of 5 to 80 nm, and even more preferably, an average primary particle diameter of 10 to 60 nm. The average primary particle size of the metal oxide can be measured using the same method as the method for measuring the average primary particle size of surface-treated metal oxides described in the examples below.

[0034] The preferred value for the kinematic viscosity of dimethylpolysiloxane used in the above-mentioned method for producing surface-treated metal oxides at 25°C is as described above.

[0035] The above method for producing surface-treated metal oxides involves a metal oxide with a kinematic viscosity of 50-500 mm² at 25°C. 2 Other steps may be included, as long as they include a mixing step of mixing dimethylpolysiloxane of / s with water and a drying step of drying the mixture obtained in the mixing step. Other steps include grinding and crushing of the surface-treated metal oxide, washing with water, drying after washing with water, sieving, etc.

[0036] 3. Dispersions, cosmetics The surface-treated metal oxide of the present invention is used as a cosmetic or the like in the form of a dispersion in a solvent such as water. Such a dispersion of surface-treated metal oxide in a solvent is also one of the present inventions.

[0037] The proportion of surface-treated metal oxide in the dispersion of the present invention is set appropriately depending on the application, but a proportion of 40% by mass or more of surface-treated metal oxide relative to 100% by mass of the dispersion is one preferred embodiment of the dispersion of the present invention. Since the surface-treated metal oxide of the present invention has sufficient hydrophobicity and good dispersibility in water, it forms a uniformly dispersed dispersion even when blended with water at relatively high concentrations. The proportion of surface-treated metal oxide in the dispersion is more preferably 45% by mass or more, and even more preferably 50% by mass or more, relative to 100% by mass of the dispersion.

[0038] The surface-treated metal oxide of the present invention can be widely used as a raw material for cosmetics overseas, and can be used as is or as a dispersion in water. Cosmetics containing such surface-treated metal oxides, and cosmetics containing the dispersion of the present invention, are also part of the present invention.

[0039] The proportion of the surface-treated metal oxide in the cosmetic composition of the present invention is not particularly limited, but it is preferably 2 to 30% by mass based on 100% by mass of the cosmetic composition. More preferably, it is 5 to 25% by mass, and even more preferably, it is 8 to 20% by mass. [Examples]

[0040] Specific examples are given below to illustrate the present invention in detail, but the present invention is not limited to these examples. Unless otherwise specified, "%" and "wt%" mean "weight % (mass %)". The measurement methods for each physical property are as follows.

[0041] <Viscosity Stability Evaluation> 1. Preparation of the dispersion 50 g of surface-treated metal oxide powder was dispersed with 8 g of PEG-10 dimethicone (Shin-Etsu Chemical Co., Ltd., KF-6017P), 42 g of cyclopentasiloxane (Shin-Etsu Chemical Co., Ltd., KF-995), and 100 g of 0.5 mmφ zirconia beads in a paint shaker for 60 minutes to obtain a dispersion. The viscosity of the obtained dispersion was evaluated as follows. 2.Viscosity measurement (1) The obtained dispersion was placed in a sample tube and allowed to stand at 25°C for 1 day, after which it was measured using a B-type viscometer (LVDV1M, manufactured by Eiko Seiki Co., Ltd., rotor No. 3, rotation speeds of 12 and 60 rpm). The measurement temperature was 25°C. (2) The dispersion was then stored in a dryer at 40°C, and the viscosity change over time from 1 week to 3 weeks was measured to evaluate its viscosity stability.

[0042] <Evaluation of powder properties> 1. Specific surface area (m 2 / g) The BET specific surface area (SSA) was measured under the following conditions. -Measurement conditions- Equipment used: Mountech Macsorb Model HM-1220 Atmosphere: Nitrogen gas (N2) Degassing conditions for external degasser: 230°C - 30 minutes Degassing conditions for the specific surface area measuring device: 230℃-5min 2.Average primary particle diameter (nm) The primary particle diameters of 200 randomly selected surface-treated metal oxide particles were measured using scanning electron microscopy (SEM) images, and the average primary particle diameter was calculated. The diameter of the smallest circumscribed circle was used to calculate the primary particle diameter of each individual particle. 3.Drying loss (%) Two grams of surface-treated metal oxide powder were accurately weighed to three decimal places, dried at 105°C for two hours, and the weight was calculated from the difference in weight before and after drying. 4.Ignition loss (%) Two grams of surface-treated metal oxide powder were accurately weighed to three decimal places, heated strongly at 500°C for one hour, and the weight was calculated from the difference in weight before and after heating. 5.Oil absorption amount A low oil absorption rate indicates good compatibility with the oil. (1) Weigh 0.5 g of surface-treated metal oxide powder accurately. (2) Place the precisely weighed powder on the 10 cm frosted glass portion in the center of the glass plate. (3) Put the measuring oil (isopropyl myristate: manufactured by Kao Corporation, Excepearl IPM) into a microburette, drop 0.2 mL onto the powder, and mix with a metal spatula. (4) Then, add the measuring oil one to two drops at a time, mixing the whole mixture with a metal spatula each time a drop is added. (5) The endpoint is defined as the first time the entire structure becomes a putty-like mass. (6) The amount of oil absorbed is calculated using the following formula. Oil absorption amount = (ml / 100g) = V (mL) ÷ powder weight (g) × 100 *In the formula, V represents the amount of oil added (mL). 6.Water repellency 1 g of surface-treated metal oxide powder was gently placed on the surface of 100 ml of pure water, stirred for 1 minute using a magnetic stirrer at 60 rpm, and then the water repellency was visually evaluated according to the following criteria. ○: Almost all of the powder is floating on the surface of the water. △: More than half of the powder is floating on the water surface, but some of it has blended with the water. ×: Most of the powder has been mixed with water. 7. Amount of surface treatment agent coating (1) Place 1 g of surface-treated metal oxide powder and 20 ml of hexane into a 50 mL centrifuge tube and shake in a shaker for 10 minutes. (2) The powder and solvent are separated by centrifugation at 5000 rpm for 10 minutes using a centrifuge, and only the solvent is transferred to a beaker of known weight. (3) Add 20 ml of hexane to the centrifuge tube from which the solvent was removed in (2), and shake it in a shaker for 10 minutes. (4)(3) is centrifugated at 5000 rpm for 10 minutes to separate the powder from the solvent. Only the solvent is collected and added to the beaker from (2), and the weight of the solvent is measured. (5) Evaporate all of the solvent from (4) in a water bath set to 80°C. (6) Dry the beaker containing the residue at 105°C for 60 minutes, measure the weight of the beaker, and measure the weight of the residue. (7) Calculate the coverage rate of the surface treatment agent on the surface-treated metal oxide powder from the weight of the residue. Coverage rate (%) = 100 - (Weight of residue / Amount of surface treatment agent in 1g of surface-treated metal oxide powder × 100) (8) The average value of N=3 was taken as the coverage rate. (9) The amount of coverage was calculated from the coverage rate calculated from the processing volume. Coating amount (g) = Amount of surface treatment agent in 100g of surface-treated metal oxide powder × Coating rate / 100 8.Optical properties Powder was placed in a 100ml mayonnaise bottle, and acrylic resin (Dainippon Ink Co., Ltd., Acrydic A-801P), butyl acetate, and xylene were added. 100g of Φ1.5 glass beads were added to this mixture and dispersed in a paint shaker for 90 minutes. This dispersion was uniformly applied to a glass slide, and the transmittance was measured using a spectrophotometer (V-770: JASCO Corporation). Visible light transparency was evaluated using the parallel transmittance, and UV shielding performance was evaluated using the total transmitted light transmittance with an integral class.

[0043] Example 1 For 100g of zinc oxide (particle size 35nm: manufactured by Sakai Chemical Industry Co., Ltd., FINEX-30), the kinematic viscosity at 25°C is 100mm. 2 Eight g of dimethylpolysiloxane (Shin-Etsu Chemical Co., Ltd., KF-96A-100cs) was added, and then the mixture was mixed while adding 5% water relative to the amount of zinc oxide powder. After that, it was heated at 300°C for 2 hours to obtain the surface-treated zinc oxide powder of Example 1.

[0044] Example 2 The kinematic viscosity at 25°C is 350 mmHg. 2 The surface-treated zinc oxide powder of Example 2 was obtained in the same manner as in Example 1, except that it was dimethylpolysiloxane (manufactured by Shin-Etsu Chemical, KF-96A-350cs) of a concentration of 1 / s.

[0045] Comparative Example 1 For 100g of zinc oxide (particle size 35nm: manufactured by Sakai Chemical Industry Co., Ltd., FINEX-30), the kinematic viscosity at 25°C is 1000mm. 2 Eight g of dimethylpolysiloxane (Shin-Etsu Chemical Co., Ltd., KF-96-1000cs) was added, and then the mixture was mixed while adding 5% water relative to the amount of powder. After that, it was heated at 300°C for 2 hours to obtain the surface-treated zinc oxide powder of Comparative Example 1.

[0046] Comparative Example 2 The kinematic viscosity at 25°C is 100 mm². 2 A surface-treated zinc oxide powder for Comparative Example 2 was obtained in the same manner as for Comparative Example 1, except that it was dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., KF-96A-100cs) with a concentration of 1 / s and no water was added.

[0047] Comparative Example 3 The kinematic viscosity at 25°C is 30 mm². 2 A powder of surface-treated zinc oxide for Comparative Example 3 was obtained in the same manner as in Example 1, except that it was dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., KF-96A-30cs) of a concentration of 1 / s.

[0048] The powders of Examples 1 and 2 and Comparative Examples 1 to 3 were evaluated for their physical properties and viscosity over time. The results are shown in Table 1. Furthermore, the powders of Examples 1 and 2 and Comparative Examples 1 to 3 were evaluated for their optical properties. The results are shown in Figures 1 and 2.

[0049] [Table 1] In Table 1, the shaded areas in the time-dependent viscosity stability evaluation indicate that viscosity measurement was not possible due to excessively high viscosity.

[0050] As shown in Table 1, the oil absorption capacity of the powders in Examples 1 and 2 was confirmed to be 20 ml / 100 g or less. Furthermore, when comparing the dispersions of the examples with those of the comparative examples, the dispersions using surface-treated zinc oxide in Examples 1 and 2 showed excellent viscosity stability over time, while the dispersions using surface-treated zinc oxide in Comparative Examples 1 and 3 increased in viscosity significantly immediately after preparation. The dispersion using surface-treated zinc oxide in Comparative Example 2 increased in viscosity significantly over time. Regarding optical properties, a lower transmittance in the UV region indicates higher UV shielding. Comparing the dispersion paint of Example 1 and the dispersion paint of Comparative Example 1 in Figure 1, it was confirmed that the dispersion paint of Example 1 had lower transmittance than the dispersion paint of Comparative Example 1 at wavelengths of 300-400 nm. Furthermore, comparing the dispersion paint of Example 1 and the dispersion paint of Comparative Example 2, it was confirmed that the dispersion paint of Example 1 had lower transmittance than the dispersion paint of Comparative Example 2 at wavelengths of 370 nm to 400 nm. From these findings, it can be concluded that the dispersion paint of Example 1 has higher UV shielding than the dispersion paint of Comparative Example 2. Figure 2 shows that in the visible light region, the dispersion coatings of Examples 1 and 2 all exhibited higher transmittance than the dispersion coatings of Comparative Examples 1 to 3.

[0051] Dimethylpolysiloxane exhibits superior hydrophobicity at higher kinematic viscosity, but excessively high viscosity leads to aggregation. Therefore, in Comparative Example 1, which used dimethylpolysiloxane with high kinematic viscosity, the dispersion is thought to have become significantly thicker due to aggregation rather than dispersion of the powder during dispersion preparation, and due to adsorption of oil due to its high oil absorption capacity. On the other hand, in Comparative Example 3, which used dimethylpolysiloxane with low kinematic viscosity, the dispersion is thought to have become significantly thicker due to its low hydrophobicity. In Comparative Example 2, only the surface treatment agent was added during the mixing process with zinc oxide, whereas in Example 1, an appropriate amount of water was added along with the surface treatment agent. Adding water promotes the adsorption reaction of the surface treatment agent to zinc oxide through catalytic action. Therefore, although the treatment agent and processing amount were the same, it is thought that the oil absorption amount and dispersion viscosity stability differed. Regarding optical properties, UV shielding performance is influenced by particle size and the dispersibility of the coating film. Since all particle sizes are the same, differences in dispersibility lead to differences in UV shielding performance and transparency. Therefore, the powder in the example is considered to be less prone to aggregation and exhibits superior dispersibility.

[0052] Examples 3, 4, Comparative Examples 4-6 Using the powders from Examples 1-2 and Comparative Examples 1-3, sunscreen O / W emulsions with the compositions shown in Table 2 were prepared by the following method. <How to prepare sunscreen O / W lotion> (1) Mixture A was prepared by mixing components 1 to 7 in Table 2 while heating them to 80°C. (2) Mixture B was prepared by mixing components 8-13 from Table 2 while heating them to 80°C. (3) A sunscreen O / W emulsion was prepared by adding mixture A to mixture B and emulsifying it.

[0053] [Table 2]

[0054] The emulsions of Examples 3 and 4 and Comparative Examples 4-6 were evaluated for quality using the following method. The results are shown in Table 3. <Stability evaluation of sunscreen O / W lotion> The prepared O / W sunscreen cream was left to stand at 50°C for one month, and then checked for any increase in thickness. [Evaluation Criteria] ◎: Not thickened ○: Slightly thicker △: Thickened ×: It has become significantly thickened and gelled. <Evaluation of user experience> Each panel of 10 people applied a molded product, obtained by hand-pressing each sample into a rectangular aluminum dish container, to their skin using a puff. They then evaluated the product's feel (moisture, non-stickiness, uniformity and evenness) on a 5-point scale according to the following criteria, and the average score was used for evaluation. [Evaluation Criteria] 5 points: very good 4 points: Good 3 points: normal 2 points: Slightly poor 1 point: Defective

[0055] [Table 3]

[0056] The O / W emulsion of Example 3, which incorporated the powder of Example 1, was confirmed to have superior stability and usability.

[0057] Examples 5, 6, Comparative Examples 7-9 Using the powders from Examples 1-2 and Comparative Examples 1-3, sunscreen W / O emulsions with the compositions shown in Table 4 were prepared by the following method. <How to prepare sunscreen W / O lotion> (1) Mixture A was prepared by uniformly mixing components 1 to 5 in Table 4 at room temperature. (2) Mixing components 6-7 from Table 4 while heating to 80°C, and adding them to mixture A to prepare mixture B. (3) Components 8-9 from Table 4 were added to mixture B and thoroughly dispersed to prepare mixture C. (4) Components 10-13 from Table 4 were mixed while being heated to 95°C, and gradually mixed into dispersion C while stirring to prepare mixture D. (5) After thoroughly mixing mixture D, it was cooled to 25°C to obtain an emulsion.

[0058] [Table 4]

[0059] The emulsions of Examples 5 and 6, and Comparative Examples 7-9 were evaluated for quality using the same method as for the emulsions of Examples 3 and 4 and Comparative Examples 4-6. The results are shown in Table 5.

[0060] [Table 5]

[0061] The W / O emulsion of Example 5, which incorporated the powder of Example 1, was confirmed to have excellent stability and usability.

Claims

1. A surface-treated metal oxide in which a metal oxide has been surface-treated with dimethylpolysiloxane, The dimethylpolysiloxane has a kinematic viscosity of 50 to 500 mm at 25°C. ２ / s, The surface-treated metal oxide is characterized by having an oil absorption capacity of 20 ml / 100 g or less.

2. The surface-treated metal oxide according to claim 1, characterized in that the amount of surface treatment with dimethylpolysiloxane is 4 to 15% by mass relative to 100% by mass of the metal oxide.

3. A dispersion obtained by dispersing the surface-treated metal oxide described in claim 1 or 2 in a solvent.

4. The dispersion according to claim 3, characterized in that the proportion of the surface-treated metal oxide to the dispersion is 40% by mass or more.

5. A cosmetic composition characterized by comprising a surface-treated metal oxide as described in claim 1 or 2.

6. A cosmetic composition characterized by comprising the dispersion described in claim 3.

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