Zinc oxide coated powder and method for producing the same, as well as sebum-solidified powder and cosmetics

Abstract

To provide zinc oxide coated powders, etc., that can achieve a higher sebum solidification effect compared to conventional products. [Solution] The present invention provides zinc oxide coated powder, which is obtained by coating porous spherical silica or fine particle silica aggregates with zinc oxide, or zinc oxide coated powder, which is obtained by coating a hygroscopic carrier with zinc oxide, wherein the moisture absorption rate HA of the zinc oxide coated powder, as determined from the following formula (1), is 1% by mass or more. The moisture absorption rate of zinc oxide coated powder is HA = [(BA) / A] × 100...(1) However, A is the mass of the zinc oxide coated powder after drying at 105°C for 3 hours, and B is the mass of the dried zinc oxide coated powder after being left for 24 hours in a constant temperature and humidity chamber set to 30°C and 75% relative humidity.

Description

[Technical Field]

[0001] This invention relates to zinc oxide coated powder, a method for producing zinc oxide coated powder, sebum-solidifying powder, and cosmetics. [Background technology]

[0002] Zinc oxide reacts with fatty acids (e.g., oleic acid) contained in sebum secreted on the skin's surface to produce metallic soaps (e.g., zinc oleate), which solidify the sebum, thus having a sebum-solidifying effect. For this reason, zinc oxide is used as an agent to prevent shine and makeup breakdown caused by sebum secretion. The sebum-solidifying effect of zinc oxide increases with smaller particle size and larger specific surface area of ​​zinc oxide particles. However, when zinc oxide comes into direct contact with the skin in the form of small-diameter particles, it can worsen the feel of the product and cause a squeaky sensation.

[0003] Therefore, zinc oxide coated powders have been proposed, in which zinc oxide is coated onto a substrate (see, for example, Patent Document 1), and a plate-shaped iron oxide coated titanium mica with a smooth surface is used as the substrate. Furthermore, the applicant already manufactures and sells zinc oxide-coated talc powder, which is a layered powder of talc used as a substrate coated with zinc oxide (see, for example, Non-Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 3522955 [Non-patent literature]

[0005] [Non-Patent Document 1] Fuji Chemical Co., Ltd., Cosmetics & Raw Materials Search, [online], Searched June 24, 2025, Internet<URL:https: / / fuji-kasei-database.com / materials / 00173 / > [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, zinc oxide-coated powders incorporated into various cosmetics are desired to have a high sebum-solidifying effect under various usage conditions. However, the zinc oxide-coated powders described in the prior art above do not necessarily have the optimal substrate (carrier) selected according to the usage conditions, and the zinc oxide is not coated on the substrate in an optimal state. As a result, a high sebum-solidifying effect may not be obtained in situations where moisture from the air or sweat is present in high-temperature, high-humidity environments. Consequently, sebum that has not been sufficiently solidified becomes more fluid due to moisture from the air or sweat in high-temperature, high-humidity environments, leading to a problem where makeup easily breaks down.

[0007] This invention has been made in view of the above problems, and aims to provide a zinc oxide coated powder that can obtain a higher sebum solidification effect than conventional methods, a method for producing the same, and a sebum solidification powder and cosmetic. [Means for solving the problem]

[0008] To solve the aforementioned problems, the present inventors diligently investigated the mechanism by which zinc oxide exhibits its sebum solidification ability. As a result, they found that moisture can promote the solidification reaction between zinc oxide and fatty acids contained in sebum, and that zinc oxide-coated powder, obtained by coating porous spherical silica or fine particle silica aggregates with zinc oxide, provides a higher sebum solidification effect compared to conventional methods. Based on the above findings, the inventors further diligently conducted research and discovered that zinc oxide-coated powder, which is obtained by coating a carrier selected from porous spherical silica, fine particle silica aggregates, and a hygroscopic carrier that can effectively adsorb moisture from the air and moisture from sweat in high-temperature, high-humidity environments with zinc oxide in a manner that maximizes the sebum solidification effect, can promote the solidification reaction between zinc oxide and fatty acids contained in sebum by the moisture adsorbed by the carrier, and thus obtain a higher sebum solidification effect than conventional methods in the presence of moisture, leading to the present invention.

[0009] The present invention is based on the above findings by the present inventor, and the means for solving the above problems are as follows.

[0010] The zinc oxide-coated powder of the present invention is obtained by coating porous spherical silica The entire surface with Spherical zinc oxide and plate-like zinc oxide in a mixed state zinc oxide. The zinc oxide-coated powder has a linseed oil absorption capacity of 120 mL / 100 g to 140 mL / 100 g. The zinc oxide-coated powder has a moisture absorption rate HA of the zinc oxide-coated powder determined by the following formula (1) of 1% by mass or more ru. Moisture absorption rate HA of zinc oxide-coated powder = [(B - A) / A] × 100 ··· (1) However, in the above formula (1), A is the mass after drying the zinc oxide-coated powder at 105°C for 3 hours, and B is the mass after leaving the dried zinc oxide-coated powder in a thermo-hygrostat set at a temperature of 30°C and a relative humidity of 75% for 24 hours.

[0011] Preferably, the zinc oxide coated powder has a zinc oxide peak in the X-ray diffraction pattern where 2θ is between 30° and 60°. . The zinc oxide-coated powder It is preferable that the amount of zinc oxide coating is 10% to 30% by mass relative to the total amount of porous spherical silica and zinc oxide. . The zinc oxide coated powder has an average circularity of 0.8 or higher for porous spherical silica, and the BET specific surface area of ​​the porous spherical silica is 100 m². 2 / g or more 1000m 2 It is preferable that the amount is less than or equal to / g, and that the moisture absorption rate HB of the porous spherical silica, calculated from the following formula (1'), is 1% by mass or more. The moisture absorption rate of porous spherical silica is HB = [(B'-A') / A'] × 100···(1') However, in formula (1) above, A' is the mass of porous spherical silica after drying at 105°C for 3 hours, and B' is the mass of dried porous spherical silica after being left for 24 hours in a constant temperature and humidity chamber set to 30°C and 75% relative humidity. .

[0012] The zinc oxide-coated powder of the present invention is formed by aggregating spherical silica primary particles to form secondary particles, and coating the surface of the particulate silica aggregate having voids All with Spherical zinc oxide and plate-like zinc oxide in a mixed state zinc oxide. The zinc oxide-coated powder has a peak of zinc oxide at 2θ of 30° to be 60° in the X-ray diffraction pattern. The zinc oxide-coated powder has a moisture absorption rate HA of the zinc oxide-coated powder determined by the following formula (1) of 1% by mass or more. Moisture absorption rate HA of zinc oxide-coated powder = [(B - A) / A] × 100 ··· (1) However, in the formula (1), A is the mass after drying the zinc oxide-coated powder at 105 °C for 3 hours, and B is the mass after leaving the dried zinc oxide-coated powder in a thermo-hygrostat set at a temperature of 30 °C and a relative humidity of 75% for 24 hours.

[0013] The zinc oxide-coated powder preferably has a linseed oil absorption of 280 mL / 100 g to 300 mL / 100 g. The zinc oxide-coated powder preferably has a coating amount of zinc oxide of 10% to 40% by mass based on the total amount of the fine particle silica aggregate and zinc oxide. The zinc oxide-coated powder has an average particle diameter of the fine particle silica aggregate of 1 μm to 10 μm, a BET specific surface area of the fine particle silica aggregate of 50 m 2 / g or more and 300 m 2 / g or less, and preferably has a moisture absorption rate HB of the fine particle silica aggregate determined from the following formula (1') of 1% by mass or more. Moisture absorption rate HB of fine particle silica aggregate = [(B' - A') / A'] × 100 ··· (1') However, in the formula (1), A' is the mass after drying the fine particle silica aggregate at 105 °C for 3 hours, and B' is the mass after leaving the dried fine particle silica aggregate in a thermo-hygrostat set at a temperature of 30 °C and a relative humidity of 75% for 24 hours.

[0014] The sebum-solidifying powder of the present invention is composed of the zinc oxide-coated powder of the present invention.

[0015] The cosmetic of the present invention contains the zinc oxide-coated powder of the present invention.

[0016] The method for producing the zinc oxide-coated powder of the present invention is a method for producing the zinc oxide-coated powder of the present invention, porous spherical silica or adding and mixing a zinc compound to an aqueous dispersion of fine particle silica aggregate, dropping an aqueous alkali solution into the obtained mixed solution to carry out a neutralization reaction, and depositing zinc oxide on the or fine particle silica aggregate.

Advantages of the Invention

[0017] According to the present invention, it is possible to provide a zinc oxide coated powder that can obtain a higher sebum solidification effect compared to conventional methods, a method for producing the same, and a sebum solidification powder.

[0018] The present invention provides a cosmetic composition that is effective in preventing shine and makeup breakdown caused by sebum secretion, and offers good usability and long-lasting wear. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a scanning electron microscope image of the zinc oxide coated powder in Test Example 1. [Figure 2] Figure 2 shows the XRD spectrum of the zinc oxide coated powder in Test Example 1. [Figure 3] Figure 3 is a scanning electron microscope image of the zinc oxide coated powder in Test Example 3. [Figure 4] Figure 4 shows the XRD spectrum of the zinc oxide coated powder in Test Example 3. [Figure 5] Figure 5 shows the SEM-EDX measurement results of zinc oxide coated powder in Test Example 3. [Modes for carrying out the invention]

[0020] (Zinc oxide coated powder) In the first embodiment, the zinc oxide coated powder of the present invention is obtained by coating porous spherical silica with zinc oxide. In the second embodiment, it is obtained by coating fine silica aggregates with zinc oxide. In the third embodiment, it is obtained by coating a hygroscopic carrier with zinc oxide, and the moisture absorption rate HA of the zinc oxide coated powder, calculated from the following formula (1), is 1% by mass or more. The moisture absorption rate of zinc oxide coated powder is HA = [(BA) / A] × 100...(1) However, in formula (1), A is the mass of the zinc oxide coated powder after drying at 105°C for 3 hours, and B is the mass of the dried zinc oxide coated powder after being left for 24 hours in a constant temperature and humidity chamber set to a temperature of 30°C and a relative humidity of 75%.

[0021] In the present invention, the zinc oxide coated powder has a moisture absorption rate HA of 1% by mass or more, preferably 1.5% by mass or more, more preferably 3% by mass or more, and particularly preferably 5% by mass or more, as determined from the above formula (1). There is no particular upper limit to the moisture absorption rate HA of the zinc oxide coated powder, and it can be appropriately selected depending on the purpose. If the moisture absorption rate HA of the zinc oxide coated powder is less than 1% by mass, the amount of moisture adsorbed onto the zinc oxide coated powder is insufficient. This prevents the solidification reaction between zinc oxide and fatty acids contained in sebum from being promoted, and may result in a lower sebum solidification effect compared to conventional methods.

[0022] <Zinc Oxide> The zinc oxide is coated on the surface of one of the following carriers: porous spherical silica, fine particle silica aggregates, or a hygroscopic carrier. It is sufficient for the zinc oxide to coat at least a portion of the carrier surface, but the entire carrier surface may also be coated with zinc oxide. Zinc oxide may be bonded to the support surface by any chemical bond, such as hydrogen bonds, van der Waals bonds, or metallic bonds, or it may be held by any interaction, such as adhesion, cohesiveness, or adsorption. The shape of the zinc oxide on the carrier surface is not particularly limited and can be appropriately selected depending on the purpose. Examples include spherical, ellipsoidal, flattened, plate-like, rod-like, needle-like, irregularly shaped, or a mixture thereof.

[0023] The amount of zinc oxide coating on the hygroscopic carrier is preferably 5% to 50% by mass, more preferably 10% to 40% by mass, and even more preferably 10% to 30% by mass. If the amount of zinc oxide coating is less than 5% by mass, the excellent sebum-solidifying effect due to the zinc oxide coating may not be obtained, and if it exceeds 50% by mass, uncoated free zinc oxide may be present, which may result in a poor texture. The amount of zinc oxide coating is expressed as mass percentage when the total amount of zinc oxide-coated powder is considered to be 100% by mass.

[0024] <Moisture-absorbing carrier> A hygroscopic carrier is a carrier whose moisture absorption rate HB, represented by the following formula (1'), is 1% by mass or more. The moisture absorption rate of a hygroscopic carrier HB = [(B'-A') / A'] × 100···(1') However, in equation (1), A' is the mass of the hygroscopic carrier after drying at 105°C for 3 hours, and B' is the mass of the dried hygroscopic carrier after being left for 24 hours in a constant temperature and humidity chamber set to a temperature of 30°C and a relative humidity of 75%.

[0025] The moisture absorption rate HB of the hygroscopic carrier is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 5% by mass or more, and particularly preferably 10% by mass or more. There is no particular upper limit to the moisture absorption rate HB of the hygroscopic carrier, and it can be appropriately selected depending on the purpose. If the moisture absorption rate HB is less than 1% by mass, the hygroscopic carrier may not be able to adsorb enough moisture, and therefore, a good sebum solidification effect may not be obtained in the presence of moisture.

[0026] The shape of the hygroscopic carrier is not particularly limited and can be appropriately selected depending on the purpose. Examples include spherical, ellipsoidal, flattened, plate-shaped, rod-shaped, needle-shaped, irregularly shaped, or a mixture thereof.

[0027] The hygroscopic carrier is not particularly limited as long as the moisture absorption rate HB of the hygroscopic carrier represented by the above formula (1') is 1% by mass or more. Examples include silicon dioxide (silica), mesoporous silica, aluminum oxide (alumina), calcium carbonate, zeolite, calcium hydrogen phosphate, and hydroxyapatite. These may be used individually or in combination of two or more. Among these, silicon dioxide (silica) and hydroxyapatite are preferred.

[0028] In the present invention, porous spherical silica or fine particle silica aggregates are preferably used as hygroscopic carriers because they have a high moisture absorption rate HB represented by the above formula (1').

[0029] - Porous spherical silica Porous spherical silica is a porous silica structure that is hydrophilic and has minute pores inside. Even the minute pores inside that open to the surface are included in the surface of the porous silica. Porous spherical silica preferably has a spherical shape. Here, the spherical shape means that the average circularity determined by an image analysis method using a scanning electron microscope (SEM) is 0.8 or more.

[0030] The BET specific surface area of porous spherical silica is preferably 30 m 2 / g or more, more preferably 50 m 2 / g or more, still more preferably 100 m 2 / g or more, particularly preferably 150 m 2 / g or more. The upper limit value of the BET specific surface area of porous spherical silica is not particularly limited and can be appropriately selected according to the purpose, but it is preferably 1000 m 2 / g or less. The BET specific surface area of porous spherical silica can be measured, for example, by a gas adsorption method using nitrogen gas. The detailed measurement method of the BET specific surface area is as described in the examples below.

[0031] The average particle diameter of porous spherical silica is preferably 0.1 μm to 10 μm, more preferably 1 μm to 10 μm. The average particle diameter can be measured, for example, by a laser diffraction / scattering method.

[0032] As the porous spherical silica, those synthesized as appropriate may be used, or commercially available products may be used. Examples of commercially available products include the Sansfair series (H-51, L-51, H-52, H-53, H-122, etc.) of AGC Si-Tech Co., Ltd., the God Ball series (AF-16C, AF-6C, B-25C, etc.) of Suzuki Oil & Fat Co., Ltd., (SUNSIL-130, C70L-E, etc.) of SUNJIN BEAUTY SCIENCE CO.,LTD., and the like.

[0033] -Microparticle silica aggregate- Fine silica aggregates are hydrophilic and consist of minute primary silica particles that aggregate to form secondary particles (aggregates). The voids between the silica particles that make up the fine silica aggregate are also included on the surface of the fine silica aggregate.

[0034] The BET specific surface area of ​​the silica particle aggregate is 30 m². 2 It is preferable that it be 50m or more / g 2 It is more preferable that it be 100m or more per gram. 2 It is even more preferable that the amount is 300 m² or more. There is no particular limit to the upper limit of the BET specific surface area of ​​the fine silica aggregates, and it can be appropriately selected depending on the purpose, but 300 m² is preferable. 2 It is preferable that the value be less than or equal to / g. The BET specific surface area of ​​a silica aggregate of fine particles can be measured, for example, by a gas adsorption method using nitrogen gas. A detailed method for measuring the BET specific surface area is described in the examples below.

[0035] The average particle size of the fine silica aggregate is preferably 0.1 μm to 10 μm, and more preferably 1 μm to 10 μm. The average particle size can be measured, for example, by laser diffraction / scattering.

[0036] As the fine silica aggregates, you may use ones that have been synthesized as appropriate, or you may use commercially available products. Examples of commercially available products include the Nipsil series from Tosoh Silica Co., Ltd. (E-150J, E-200, E-220A, K-500, etc.).

[0037] (Method for producing zinc oxide coated powder) The method for producing zinc oxide coated powder according to the present invention is a method for producing zinc oxide coated powder according to the present invention, A zinc compound is added to an aqueous dispersion of a carrier selected from porous spherical silica, fine particle silica aggregates, and a hygroscopic carrier, and mixed. An alkaline aqueous solution is then added dropwise to the resulting mixture to carry out a neutralization reaction, thereby precipitating zinc oxide on the carrier.

[0038] According to the method for producing zinc oxide coated powder of the present invention, the moisture absorption rate HA of the zinc oxide coated powder, as determined from the above formula (1), is 1% by mass or more, and it is possible to efficiently produce zinc oxide coated powder that has an excellent sebum solidification effect even in high-temperature, high-humidity environments where moisture is present in the air or due to sweating.

[0039] Examples of zinc compounds include zinc chloride, zinc nitrate, zinc sulfate, and zinc acetate. Examples of alkaline aqueous solutions include aqueous solutions of sodium hydroxide, potassium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate, urea, etc.; and aqueous ammonia.

[0040] The present invention provides a method for producing zinc oxide coated powder, in which an alkaline aqueous solution is dropped to induce a neutralization reaction, and zinc oxide is precipitated on a carrier selected from porous spherical silica, fine particle silica aggregates, and a hygroscopic carrier. After that, if necessary, the solid content obtained by solid-liquid separation by a conventional method is washed with water, dried, and calcined to obtain zinc oxide coated powder. The firing temperature is preferably 150°C or higher, and more preferably between 150°C and 700°C. The firing time is usually 30 minutes to 5 hours.

[0041] (Sebum-solidifying powder) The sebum-solidifying powder of the present invention consists of the zinc oxide-coated powder of the present invention. The sebum-solidifying powder of the present invention is made by coating a hygroscopic carrier, which can adsorb moisture from the air and moisture from sweat in high-temperature, high-humidity environments, with zinc oxide in a manner that maximizes the sebum-solidifying effect. Compared to conventional zinc oxide-coated powders, which are made by coating a non-hygroscopic carrier that does not adsorb moisture with zinc oxide, the present invention can achieve a superior sebum-solidifying effect even in the presence of moisture.

[0042] (Cosmetics) The cosmetic composition of the present invention contains the zinc oxide coated powder of the present invention, and further contains other components as needed.

[0043] The cosmetic composition of the present invention contains the zinc oxide coated powder of the present invention, which provides a higher sebum solidification effect compared to conventional materials. Therefore, it is effective in preventing shine and makeup breakdown caused by sebum secretion, and has good usability and long-lasting wear.

[0044] <Zinc oxide coated powder> The zinc oxide coated powder content of the present invention is preferably 0.1% to 50% by mass, more preferably 0.5% to 30% by mass, even more preferably 1% to 20% by mass, and particularly preferably 1% to 10% by mass, based on the total amount of the cosmetic. When the zinc oxide coated powder content is 0.1% to 50% by mass, it is effective in preventing shine and makeup breakdown caused by sebum secretion, and a cosmetic with good usability and long-lasting wear can be provided.

[0045] <Other ingredients> Other ingredients are not particularly limited and can be selected as appropriate depending on the purpose. Examples include oils, water, powders other than zinc oxide coated powders, surfactants, lower alcohols, polyhydric alcohols, humectants, whitening agents, UV protectants, antiperspirants, cooling agents, pH adjusters, preservatives, polymers, antioxidants, fragrances, and various pharmaceuticals.

[0046] Specific uses of the cosmetics of the present invention include, for example, lotions, creams, balms, toners, serums, cleansers, masks, washing products, sunscreens, makeup bases, face powders, powder foundations, liquid foundations, concealers, highlighters, contouring products, blushes, eyeshadows, mascaras, eyeliners, lipsticks, nail polishes, and hair care products.

[0047] Furthermore, the form of the cosmetic composition of the present invention is not particularly limited and includes, for example, powder, cream, emulsion, solid, semi-solid, stick, mousse, gel, and the like.

Example

[0048] The examples of the present invention will be described below, but the present invention is not limited to these examples at all.

[0049] (Test Example 1) 10 g of particulate silica aggregates as a hygroscopic carrier was dispersed in 100 mL of ion-exchanged water, and 0.03 mol of zinc nitrate and 0.03 mol of acetic acid were added thereto. 1 M sodium hydroxide was added dropwise to the obtained dispersion at 8 mL / min to adjust the pH to 12. This dispersion was filtered, washed with water, dried in a constant temperature bath at 105°C for 12 hours, and then calcined at a temperature of 500°C for 3 hours to obtain a zinc oxide-coated powder of Test Example 1.

[0050] (Test Example 2) 10 g of talc as a non-hygroscopic carrier was dispersed in 100 mL of ion-exchanged water, and 0.03 mol of zinc nitrate and 0.03 mol of acetic acid were added thereto. 1 M sodium hydroxide was added dropwise to the obtained dispersion at 8 mL / min to adjust the pH to 12. This dispersion was filtered, washed with water, dried in a constant temperature bath at 105°C for 12 hours, and then calcined at a temperature of 500°C for 3 hours to obtain a zinc oxide-coated powder of Test Example 2.

[0051] <SEM Observation> The zinc oxide-coated powder obtained in Test Example 1 was placed on a stage, platinum-coated, and then SEM observation was performed with a scanning electron microscope (SU1510, manufactured by Hitachi, Ltd.). As a result, as shown in Fig. 1, the surface was coated in a mixed state of spherical zinc oxide and plate-like zinc oxide.

[0052] <XRD Spectrum> The XRD spectrum measured with an X-ray diffractometer (RINT-Ultima +, manufactured by Rigaku Corporation) of the zinc oxide-coated powder obtained in Test Example 1 is shown in Fig. 2. It was confirmed from Fig. 2 that zinc oxide was coated on the surface.

[0053] Next, for the carriers and zinc oxide-coated powders of Test Examples 1 to 2, various properties were measured and evaluated as follows. The results are shown in Table 1.

[0054] <Average particle diameter> For each of the obtained zinc oxide-coated powders, the median diameter was calculated from the measured volume-based particle size distribution using a laser diffraction particle size distribution measuring device (SALD-2300, manufactured by Shimadzu Corporation), and this median diameter was taken as the average particle diameter.

[0055] <BET specific surface area> For each of the obtained zinc oxide-coated powders, the BET specific surface area was determined by the BET multipoint method using a specific surface area measuring device (BELSORP MINI X, manufactured by MicrotracBEL Corporation) and nitrogen gas with a purity of 99.99% or more.

[0056] <Linseed oil absorption> For each of the obtained zinc oxide-coated powders, the linseed oil absorption was measured in accordance with JIS K5101-13-1.

[0057] <Moisture absorption rate HB of the carrier> Weigh 5 g of each carrier into a magnetic flat dish, measure the mass A' after drying at 105°C for 3 hours using a dryer. Then, measure the mass B' after leaving the dried carrier in a thermo-hygrostat set at a temperature of 30°C and a relative humidity of 75% for 24 hours. The measured masses A' and B' were used to determine the moisture absorption rate HB of the carrier by the following formula (1'). Moisture absorption rate HB of the carrier = [(B' - A') / A'] × 100 ··· (1')

[0058] <Moisture absorption rate HA of the zinc oxide-coated powder> Weigh 5 g of each of the obtained zinc oxide-coated powders into a magnetic flat dish, measure the mass A after drying at 105°C for 3 hours using a dryer. Then, measure the mass B after leaving the dried zinc oxide-coated powder in a thermo-hygrostat set at a temperature of 30°C and a relative humidity of 75% for 24 hours. The measured masses A and B were used to determine the moisture absorption rate HA of the zinc oxide-coated powder by the following formula (1). The moisture absorption rate HA of the zinc oxide-coated powder = [(B - A) / A] × 100 ··· (1)

[0059] <固化所要時間>[<Required curing time> For each of the obtained zinc oxide-coated powders, after drying at 105°C for 3 hours, the "zinc oxide-coated powder after drying" and, after drying the zinc oxide-coated powders at 105°C for 3 hours and leaving them in a thermo-hygrostat set at a temperature of 30°C and a relative humidity of 75% for 24 hours, the "zinc oxide-coated powder after moisture absorption", the zinc oxide-coated powder and oleic acid were mixed at a ratio of 1:4 (mass ratio), and the required curing time (seconds) after drying and after moisture absorption, which is the time until oleic acid solidifies, was measured.

[0060]

Table 1

[0061] (Test Example 3) 20 g of porous spherical silica powder as a hygroscopic carrier was dispersed in 100 mL of ion-exchanged water, and 0.08 mol of zinc chloride and 0.04 mol of acetic acid were added thereto. 1 M sodium carbonate was dropped into the obtained dispersion at a rate of 4 mL / min to adjust the pH to 10. This dispersion was filtered, washed with water, dried in a thermostatic bath at 105°C for 12 hours, and then calcined in an electric furnace at 500°C for 3 hours to obtain the zinc oxide-coated powder of Test Example 3.

[0062] [[ID=e25]] <SEM Observation>[<SEM Observation> The zinc oxide-coated powder obtained in Test Example 3 was placed on a stage, platinum-coated, and then SEM observation was performed with a scanning electron microscope (SU1510, manufactured by Hitachi, Ltd.). As a result, as shown in Figure 3, the surface was coated with spherical zinc oxide and plate-like zinc oxide in a mixed state.

[0063] <XRD Spectrum>[<XRD Spectrum> The XRD spectrum of the zinc oxide-coated powder obtained in Test Example 3 measured with an X-ray diffractometer (RINT-Ultima +, manufactured by Rigaku Corporation) is shown in Figure 4. From Figure 4, it was confirmed that zinc oxide was coated on the surface.

[0064] <sem-edx> Figure 5 shows the results of SEM-EDX measurements (SEM manufactured by Hitachi High-Tech Corporation, EDX manufactured by Oxford Instruments) of the zinc oxide coated powder obtained in Test Example 3. From the results in Figure 5, it can be seen that the surface of the zinc oxide coated powder in Test Example 3 is coated with zinc oxide.

[0065] Next, the carrier and zinc oxide coated powder of Test Example 3 were measured and evaluated in the same manner as in Test Example 1. The results are shown in Table 2. The results of Test Example 2 are also included in Table 2.

[0066] [Table 2]

[0067] (Test example 4) -Loose Powder Review- Based on the formulations listed in Table 3 below, the loose powder for Test Example 4 was prepared by a conventional method.

[0068] [Table 3]

[0069] Next, the moisture absorption rate of the loose powder obtained in Test Example 4 was measured in the same manner as the moisture absorption rate measurement method in Test Example 1. In addition, the solidification time of the loose powder was measured as follows. The results are shown in Table 4.

[0070] <Time required for solidification> For both the "dried loose powder" obtained by drying the loose powder at 105°C for 3 hours and the "loose powder after moisture absorption" obtained by drying the loose powder from Test Example 4 at 105°C for 3 hours and then leaving it in a constant temperature and humidity chamber set to 30°C and 75% relative humidity for 24 hours, 0.3g of each loose powder and 1.2g of oleic acid were placed in a 10mL beaker, stirred for 20 seconds, and solidification was checked every 5 seconds. The solidification time after drying and after moisture absorption was defined as the point at which the mixture stopped flowing when the beaker was tilted.

[0071] [Table 4]

[0072] The following are examples of cosmetic formulations containing the zinc oxide coated powder of the present invention as shown in Test Example 1 and Test Example 3. However, the present invention is not limited to these.

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[0100] (Prescription example 28) TIFF0007862899000032.tif158166 [Industrial applicability]

[0101] The zinc oxide coated powder and sebum solidifying powder of the present invention provide a higher sebum solidifying effect compared to conventional materials, and can therefore be suitably applied to various cosmetic products, for example.

Claims

1. A zinc oxide coated powder in which spherical zinc oxide and plate-shaped zinc oxide are mixed and coated on the entire surface of porous spherical silica, The zinc oxide coated powder has a linseed oil absorption capacity of 120 mL / 100 g to 140 mL / 100 g. A zinc oxide coated powder having a moisture absorption rate HA of 1% by mass or more, as determined from the following formula (1). The moisture absorption rate of zinc oxide coated powder HA = [(B - A) / A] × 100 ... (1) However, in formula (1) above, A is the mass of the zinc oxide coated powder after drying at 105°C for 3 hours, and B is the mass of the dried zinc oxide coated powder after leaving it for 24 hours in a constant temperature and humidity chamber set to a temperature of 30°C and a relative humidity of 75%.

2. The zinc oxide coated powder according to claim 1, wherein the X-ray diffraction pattern shows a zinc oxide peak at 2θ between 30° and 60°.

3. The zinc oxide coated powder according to claim 1, wherein the amount of zinc oxide coating is 10% by mass to 30% by mass relative to the total amount of porous spherical silica and zinc oxide.

4. The average circularity of the porous spherical silica is 0.8 or higher, and the BET specific surface area of ​​the porous spherical silica is 100 m². ２ / g or more 1000m ２ The zinc oxide coated powder according to claim 1, wherein the amount is less than or equal to / g, and the moisture absorption rate HB of the porous spherical silica, calculated from the following formula (1'), is 1% by mass or more. The moisture absorption rate of porous spherical silica HB = [(B' - A') / A'] × 100 ... (1') However, in formula (1) above, A' is the mass of porous spherical silica after drying at 105°C for 3 hours, and B' is the mass of dried porous spherical silica after being left for 24 hours in a constant temperature and humidity chamber set to a temperature of 30°C and a relative humidity of 75%.

5. A zinc oxide coated powder is formed in which spherical primary silica particles aggregate to form secondary particles, and the entire surface of the fine silica aggregate having voids is coated with a mixture of spherical zinc oxide and plate-shaped zinc oxide. In the X-ray diffraction pattern, there is a zinc oxide peak at 2θ from 30° to 60°. A zinc oxide coated powder having a moisture absorption rate HA of 1% by mass or more, as determined from the following formula (1). The moisture absorption rate of zinc oxide coated powder HA = [(B - A) / A] × 100 ... (1) However, in formula (1) above, A is the mass of the zinc oxide coated powder after drying at 105°C for 3 hours, and B is the mass of the dried zinc oxide coated powder after leaving it for 24 hours in a constant temperature and humidity chamber set to a temperature of 30°C and a relative humidity of 75%.

6. The zinc oxide coated powder according to claim 5, wherein the amount of linseed oil absorbed is 280 mL / 100 g to 300 mL / 100 g.

7. The zinc oxide coated powder according to claim 5, wherein the amount of zinc oxide coating is 10% by mass to 40% by mass relative to the total amount of the fine silica aggregate and the zinc oxide.

8. The average particle size of the fine silica aggregate is 1 μm to 10 μm, and the BET specific surface area of ​​the fine silica aggregate is 50 m². ２ / g or more 300m ２ The zinc oxide coated powder according to claim 5, wherein the amount is less than or equal to / g, and the moisture absorption rate HB of the fine silica aggregates, calculated from the following formula (1'), is 1% by mass or more. The moisture absorption rate HB of a silica aggregate of fine particles = [(B' - A') / A'] × 100 ... (1') However, in formula (1) above, A' is the mass of the fine silica aggregate after drying at 105°C for 3 hours, and B' is the mass of the dried fine silica aggregate after leaving it for 24 hours in a constant temperature and humidity chamber set to a temperature of 30°C and a relative humidity of 75%.

9. A sebum-solidifying powder comprising a zinc oxide-coated powder according to any one of claims 1 to 8.

10. A cosmetic composition comprising the zinc oxide coated powder according to any one of claims 1 to 8.

11. A method for producing a zinc oxide coated powder according to any one of claims 1 to 8, A method for producing zinc oxide-coated powder, characterized by adding and mixing a zinc compound to an aqueous dispersion of porous spherical silica or fine particle silica aggregates, and then neutralizing the resulting mixture by dropping an alkaline aqueous solution onto the porous spherical silica or fine particle silica aggregates to precipitate zinc oxide.

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