Powder cosmetic

Abstract

The purpose of the present invention is to provide a powder cosmetic which does not aggregate even when a large amount of a particulate metal oxide powder (titanium dioxide or the like), which is an ultraviolet scattering agent, is blended therein, can obtain a high ultraviolet protection capability, and has excellent usability. The present invention relates to a powder cosmetic comprising: (a) at least one metal oxide powder selected from the group consisting of titanium dioxide, zinc oxide, and cerium oxide; and (b) silica, the metal oxide powder having an average particle diameter of 10 nm or less and being 5 mass% or more relative to the total amount of the cosmetic. It is preferable to use titanium dioxide as the metal oxide powder (a).

Description

Technical Field

[0001] The present invention relates to powder cosmetics and more particularly to powder cosmetics which do not aggregate even when a large amount of fine-particle metal oxide powder as an ultraviolet scattering agent is added and which exhibits a high ultraviolet protection capability. Background Art

[0002] Face powder is a kind of makeup cosmetic that has been widely used since ancient times, but with the change of times, its role has also changed, and its main purpose has become to eliminate the greasy sheen caused by sweat and sebum and to improve the durability of makeup. However, nowadays, wearing masks has become a daily routine to prevent the spread of infectious diseases such as the new coronavirus, and makeup behavior has also tended to be simplified. Therefore, more and more consumers are demanding high-performance powder cosmetics such as face powder that can be easily applied, such as high SPF (sun protection factor).

[0003] In order to improve the UV protection of powder cosmetics such as face powder, it is necessary to increase the amount of UV absorbers and UV scatterers. However, UV absorbers are oily substances, so it is difficult to mix them with loose powders (face powders) that contain almost no oil. In addition, if a large amount of oil such as UV absorbers is mixed, it may cause the powder to aggregate, thereby impairing the uniformity and usability of the cosmetics.

[0004] Metal oxide powders such as titanium dioxide, zinc oxide, or cerium oxide in fine particle form are widely used as ultraviolet scattering agents. Cosmetics containing ultrafine metal oxides having a particle size of 30 nm or less have the characteristics of exhibiting an ultraviolet shielding effect and having excellent transparency (Patent Document 1).

[0005] On the other hand, it is well known that powder aggregation is more likely to occur when the particle size of the powder becomes fine. Therefore, even if a large amount of micro-particles of titanium dioxide or the like are added, the improvement in the UV protection effect (high SPF) expected by increasing the amount cannot be obtained due to the aggregation of the powder. In addition, if a large amount of metal oxide powder such as an ultraviolet scattering agent is added, it may become astringent when applied, resulting in reduced usability.

[0006] In other words, in order to achieve a high ultraviolet protection effect based on fine-particle metal oxides, it is necessary to solve the problems of powder aggregation suppression and usability.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 62-84017 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] An object of the present invention is to provide a powder cosmetic which can provide high ultraviolet protection capability without aggregation even when a large amount of fine-particle metal oxide powder (such as titanium dioxide) as an ultraviolet scattering agent is added, and which is also excellent in usability.

[0012] Solutions for solving problems

[0013] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found that by increasing the amount of fine-particle metal oxide powder used as an ultraviolet scattering agent and adding silica, particularly spherical silica, the aggregation of the metal oxide powder can be suppressed, thereby achieving a high ultraviolet protection effect, thereby completing the present invention.

[0014] That is, the present invention provides a powder cosmetic, characterized in that it comprises:

[0015] (a) at least one metal oxide powder selected from titanium dioxide, zinc oxide and cerium oxide, the average particle size of which is 10 nm or less and which accounts for 5% by mass or more of the total amount of the cosmetic; and

[0016] (b) Silica.

[0017] Effects of the Invention

[0018] The powder cosmetic of the present invention contains 5% by mass or more of a metal oxide powder selected from titanium dioxide, zinc oxide and cerium oxide, and has an average particle size of 10 nm or less. Even if the powder cosmetic of the present invention is formulated with the above-mentioned metal oxide powder (i.e., ultraviolet scattering agent) in an amount of 5% by mass or more, powder aggregation will not occur, and a high ultraviolet protection effect can be obtained. That is, in the powder cosmetic of the present invention, the silica formulated together with the ultraviolet scattering agent can play a role in improving the ultraviolet protection effect brought about by the ultraviolet scattering agent (hereinafter also referred to as "enhancing effect"). When a particulate powder having an average particle size of 10 nm or less is used as the ultraviolet scattering agent (metal oxide powder), the reinforcing effect is particularly significantly exerted. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The graphs show the absorbance in the ultraviolet wavelength region of the cosmetics of Comparative Example 1 and Examples 1 to 3 shown in Table 1. In the graph, (a) shows the absorbance curve of Comparative Example 1; (b) shows the absorbance curve of Example 1; (c) shows the absorbance curve of Example 2; and (d) shows the absorbance curve of Example 3. DETAILED DESCRIPTION

[0020] The powder cosmetic of the present invention (hereinafter, sometimes simply referred to as "cosmetic") contains (a1) titanium dioxide or (a2) zinc oxide and / or (a3) ​​cerium oxide, and further contains (b) silica.

[0021] (a) Metal oxide powder

[0022] The "metal oxide powder" (also referred to as "component (a)") in the cosmetic of the present invention refers to a powder consisting of at least one selected from (a1) titanium dioxide, (a2) zinc oxide, and (a3) ​​cerium oxide.

[0023] The "(a) metal oxide powder" in the present invention is a fine-particle powder having an average primary particle size of 10 nm or less, preferably less than 10 nm.

[0024] The average primary particle size refers to the arithmetic mean of the primary particle size of the powder measured by a commonly used method. In this specification, the Feret diameter of the powder particles measured by microscopy is taken as the primary particle size of the particles, and the arithmetic mean calculated based on the distribution of the primary particle sizes (particle size distribution) obtained for a plurality of particles is taken as the average primary particle size (or average particle size). The Feret diameter refers to the distance between parallel lines when the projected image of the particle is sandwiched between two parallel lines in a certain direction.

[0025] The lower limit of the average particle size of the "(a) metal oxide powder" is not particularly limited, but is usually 1 nm or more, and preferably 5 nm or more.

[0026] The particle shape of the "(a) metal oxide powder" is not particularly limited, and includes spherical, elliptical, crushed, and the like.

[0027] In this specification, unless otherwise specified, "(a) metal oxide powder" means "powder of (a1) titanium dioxide, (a2) zinc oxide or (a3) ​​cerium oxide having an average particle size of 10 nm or less (or less)".

[0028] In the present invention, (a1) titanium dioxide is preferably used as the "(a) metal oxide powder".

[0029] Powders with various average particle sizes can be added to powder cosmetics. For example, titanium dioxide, zinc oxide, etc. with an average particle size of about 200 nm or less are generally referred to as "ultraviolet scattering agents", but if the average particle size is not less than 10 nm, they do not belong to the "(a) component" of the present invention. In addition, metal oxide powders with an average particle size exceeding about 200 nm are generally referred to as "pigment-grade metal oxide powders", and of course are not included in the "(a) component" of the present invention.

[0030] In the cosmetic of the present invention, the metal oxide powder (a) may be a powder surface-treated with a "metal soap." It is preferred to use a metal oxide powder surface-treated with a metal soap because the dispersibility of the powder is further improved.

[0031] "Metallic soap" is a salt of a metal (excluding alkali metals) of a saturated or unsaturated higher fatty acid. Although not particularly limited, examples of the higher fatty acid constituting the metal soap include saturated and / or unsaturated higher fatty acids having 8 to 24 carbon atoms, particularly 12 to 18 carbon atoms, such as stearic acid, isostearic acid, myristic acid, lauric acid, etc. As the metal constituting the metal soap, salts of aluminum, calcium, magnesium, zinc, etc. are preferred.

[0032] Specific examples of metal soaps preferably used as the surface treatment agent for the (a) metal oxide powder include aluminum stearate, aluminum myristate, magnesium myristate, zinc stearate, calcium stearate, zinc myristate, zinc oleate, magnesium isostearate, magnesium stearate, aluminum distearate, aluminum oleate, aluminum palmitate, aluminum laurate, and aluminum dimyristate.

[0033] The "metal oxide powder treated with a metal soap" in the present invention is a powder obtained by surface-treating a metal oxide powder serving as a matrix (mother core) with a treatment agent containing a component constituting a metal soap.

[0034] The surface treatment using metal soap can be implemented by a method of surface treatment with a pre-formed metal soap. For example, the metal soap can be dissolved in a volatile solvent such as isoparaffin, isopropanol, etc., mixed with the base powder, and then the volatile solvent is volatilized to perform surface treatment. In addition, even if only the base powder is mixed with the metal soap, the surface treatment can be performed. Alternatively, the surface treatment can be performed by a method of composite treatment of a higher fatty acid (e.g., stearic acid) constituting the metal soap with a hydroxide of a metal (e.g., aluminum). As a surface treatment method, a wet method using a solvent, a gas phase method, a mechanochemical method, etc. can be utilized, without particular limitation.

[0035] The amount of the (a) metal oxide powder in the cosmetic of the present invention is 5% by mass or more, preferably 10% by mass or more, and more preferably 20% by mass or more, relative to the total amount of the cosmetic. If the amount is less than 5% by mass, a sufficient ultraviolet protection effect may not be obtained. The upper limit of the amount of the (a) metal oxide powder is not particularly limited, but is usually 40% by mass or less, preferably 30% by mass or less. The amount of the (a) metal oxide powder may range from 5 to 40% by mass, 5 to 30% by mass, 10 to 40% by mass, 10 to 30% by mass, 20 to 40% by mass, 20 to 30% by mass, etc.

[0036] (b) Silica

[0037] The "silicic acid anhydride" (also referred to as "component (b)") added to the powder cosmetic of the present invention is preferably "spherical silica". When spherical silica is added, the "astringency" caused by the powder component is alleviated, and the usability is improved. "Spherical" means a true spherical shape, or a substantially spherical shape including particles with a major diameter / minor diameter ratio of 1.5 or less, preferably 1.2 or less. By adding silica, an effect of improving the ultraviolet protection effect (enhanced effect) can be obtained.

[0038] Silica (component (b)) is not particularly limited and is a spherical powder having an average particle size of 1 to 30 μm, preferably 1 to 20 μm, more preferably 2 to 15 μm. The average particle size of silica is the arithmetic mean of particle sizes measured by laser diffraction / scattering method.

[0039] Silica (component (b)) may be non-porous or porous. In order to obtain a good reinforcing effect, silica having a specific surface area of ​​160 m 2 / g or more, preferably 300m 2 / g or more, more preferably 500m 2 / g or more spherical silica.

[0040] The specific surface area of ​​silica can be calculated by measuring the amount of nitrogen gas adsorbed on powder at 77 K and analyzing it by the BET method, for example.

[0041] In addition, as the "silica (component (b))" in the present invention, it is preferable to use untreated silica that has not been surface-treated with a treatment agent containing a metal soap or the like, particularly untreated spherical silica powder.

[0042] The amount of (b) silica in the cosmetic of the present invention is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more relative to the total amount of the cosmetic. The upper limit of the amount of (b) silica is not particularly limited, but is usually 60% by mass or less, preferably 50% by mass or less relative to the total amount of the cosmetic. The amount of (b) silica may range from 10 to 60% by mass, 10 to 50% by mass, 20 to 60% by mass, 20 to 50% by mass, 30 to 60% by mass, 30 to 50% by mass, and the like.

[0043] (c)Extender pigments

[0044] In order to maintain the dosage form, powder cosmetics are often formulated with inorganic pigments called "extender pigments". The cosmetics of the present invention may also be formulated with "extender pigments" (also referred to as component (c)). Specific examples of "extender pigments (c)" include powders of talc, mica, sericite, kaolin, calcium carbonate, magnesium carbonate, aluminum oxide, barium sulfate, and the like.

[0045] The (c) extender pigment in the cosmetic of the present invention can be selected from an untreated extender pigment that has not been surface treated, or an extender pigment that has been surface treated with a metal soap, a silicone-based or amino acid-based treatment agent, etc. Among them, the amount of the extender pigment surface treated with a metal soap is preferably less than 25% by mass, more preferably less than 20% by mass. The present invention includes an embodiment that does not include an extender pigment surface treated with a metal soap.

[0046] The cosmetics of the present invention are powder cosmetics comprising (a) metal oxide powder having an average particle size of 10 nm or less and (b) silica, and optionally (c) an extender pigment, but in addition to these, any other optional ingredients commonly used in powder cosmetics may be appropriately formulated within a range that does not impair the effects of the present invention.

[0047] Examples of other optional components include other powder components (powders that do not belong to components (a), (b), and (c)), oily components, and aqueous components.

[0048] Examples of other powder components include coloring pigments such as iron oxides; white pigments such as pigment-grade titanium dioxide and zinc oxide; pearlescent pigments; and spherical powders such as cellulose powder, silicone powder, and boron nitride.

[0049] These other powder components may or may not be surface treated.

[0050] Examples of the oily component include oils such as hydrocarbon oils, fats and oils, higher alcohols, waxes, hardened oils, ester oils, fatty acids, silicone oils, fluorine-based oils, lanolin derivatives, oily gelling agents, and oily ultraviolet absorbers.

[0051] It should be noted that the addition of oil may cause aggregation of powders. Therefore, in the cosmetic of the present invention, the amount of oil is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and most preferably 2% by mass or less, relative to the total amount of the cosmetic.

[0052] In the powder cosmetic of the present invention, since the amount of oil to be blended is suppressed, the amount of oily UV absorber used is also small (for example, 2% by mass or less), but the UV protection effect based on the UV scattering agent is improved (enhanced), so a high SPF can be achieved. Therefore, a powder cosmetic that does not contain an oily UV absorber (so-called "non-chemical type") can also be made.

[0053] Examples of the aqueous component include water and water-affinity components such as lower alcohols such as ethanol, polyols such as glycerin, and water-soluble polymers.

[0054] The cosmetics of the present invention are powder cosmetics with excellent UV protection effect and usability, and can be provided in the form of loose powder that is not compressed or pressed. The form of the product provided is not limited, but it is particularly suitable for the form of face powder, foundation, eye shadow, blush, sunscreen, etc.

[0055] Example

[0056] The present invention is described in more detail below with reference to the following examples. However, the following examples do not limit the scope of the present invention in any way. It should be noted that, unless otherwise specified, the amount of the compounding agent represents the mass % relative to the total amount of the cosmetic.

[0057] Powder cosmetics were prepared according to a conventional method according to the formulations shown in Table 1. The cosmetics (10 mg) of each example were applied to a PMMA plate, and the absorbance to light in the ultraviolet wavelength region (280 to 400 nm) was measured and the absorbance in the ultraviolet wavelength region was integrated.

[0058] The absorbance curves obtained in the cosmetics of each example are shown in Figure 1 (a) is the absorbance curve of Comparative Example 1, (b) is the absorbance curve of Example 1, (c) is the absorbance curve of Example 2, and (d) is the absorbance curve of Example 3. It can be confirmed that the absorbance to ultraviolet light increases by adding silica to cosmetics. As the amount of silica added increases, the increase in absorbance increases.

[0059] The integral value of the absorbance curve obtained in the cosmetic of "Comparative Example 1" is defined as the "baseline integral value", the integral value of the absorbance curve obtained in the cosmetics of Examples 1 to 3 is defined as the "actually measured integral value", and the value calculated using the following formula is defined as the "enhancement rate" as an evaluation index of the ultraviolet protection ability.

[0060] Enhancement rate = (measured integral value / reference integral value) × 100

[0061] That is, cosmetics with an "enhancement rate" exceeding 100 indicate that the UV protection capability is improved (has an enhancement effect) by adding silica, and a larger value indicates a greater enhancement effect. The "enhancement rate" of each example is shown in Table 1.

[0062] [Table 1]

[0063]

[0064] (*1) Aluminum stearate treated titanium dioxide (average particle size = 8 nm)

[0065] The results in Table 1 (enhancement ratio) increase with the increase of silica content, which is consistent with the results obtained by Figure 1 The results inferred from the comparison of the absorbance curves are consistent.

[0066] Next, the same evaluation as above was performed for cosmetics in which the "untreated mica" in the formulation of Table 1 was replaced with other extender pigments (untreated talc) (Table 2). The formulations and evaluation results (enhancement rate) of each example are shown in the following Table 2. For the cosmetics in which "talc" was formulated as an extender pigment (Examples 4 to 6), similarly to the cosmetics in which "mica" was formulated (Examples 1 to 3), an "enhancement effect" was confirmed in which the "enhancement rate" increased with the increase in the amount of silica formulated.

[0067] [Table 2]

[0068]

[0069] (*1) Aluminum stearate treated titanium dioxide (average particle size = 8 nm)

[0070] Here, the same evaluation as above was performed on cosmetics (reference examples 1 and 2, respectively) except that the titanium dioxide with an average particle size of 15 nm or less (a) in comparative example 2 and example 6 in Table 2 was replaced with titanium dioxide with an average particle size of 10 nm. The results are shown in Table 3 below.

[0071] In the reference example using titanium dioxide with an average particle size of 15 nm, although the "enhancement effect" of the ultraviolet protection ability brought about by the addition of silica was observed, the absolute value of the "enhancement rate" was significantly increased when titanium dioxide with an average particle size of less than 10 nm was used. In order to show this fact, Table 3 shows not only the enhancement rate of Example 6 calculated using Comparative Example 2 as the reference integral value, but also the enhancement rate of Example 6 calculated using Reference Example 1 or Reference Example 2 as the reference integral value.

[0072] [Table 3]

[0073]

[0074] (*1) Aluminum stearate treated titanium dioxide (average particle size = 8 nm)

[0075] (*2) Aluminum stearate treated titanium dioxide (average particle size = 15 nm)

[0076] For Example 6 in Table 2, the "silica" (porous spherical silica powder) was replaced with a specific surface area of ​​10 m 2 The cosmetics containing nonporous silica having a content of 0.1 wt. % or less (Example 7) were evaluated in the same manner as above.

[0077] [Table 4]

[0078]

[0079] (*1) Aluminum stearate treated titanium dioxide (average particle size = 8 nm)

[0080] As shown in Table 4, it was confirmed that the blended "silica" showed improvement (enhancement effect) in ultraviolet protection effect regardless of whether it was porous or non-porous. However, when porous silica was used, the absolute value of the "enhancement rate" (i.e., the magnitude of the enhancement effect) was large.

[0081] The following describes formulation examples of powder cosmetics (loose powder and pressed powder) according to the present invention. Any formulation can achieve a non-astringent usability and a high UV protection effect.

[0082] Formula Example 1 (Loose Powder)

[0083] [Table 5]

[0084] Compounding ingredients Compounding amount (mass %) Mica margin Metallic soap treated mica 10 Boron Nitride 10 Amino Acid Powder (Lauroyl Lysine) 2 Starch powder 2 Metal soap (calcium myristic acid) 6 Barium sulfate 1 Porous silica 10 Non-porous silica 15 Metal soap treated titanium dioxide 25 Zinc Oxide 7 preservative Moderate Antioxidants Moderate Coloring Materials 1.5 Pearlescent Agent 0.2 Food flavors Moderate total 100

[0085] Formula Example 2 (Loose Powder)

[0086] [Table 6]

[0087] Compounding ingredients Compounding amount (mass %) Mica margin Metallic soap treated mica 10 Barium sulfate 1 Porous silica 30 Non-porous silica 10 Metal soap treated titanium dioxide 25 Zinc Oxide 7 preservative Moderate Antioxidants Moderate Coloring Materials 1.5 Pearlescent Agent 10 Food flavors Moderate total 100

[0088] Formula Example 3 (Pressed Powder)

[0089] [Table 7]

[0090] Compounding ingredients Compounding amount (mass %) Mica margin Metallic soap treated mica 30 Metal soap (calcium myristic acid) 5 Porous silica 10 Non-porous silica 3 Metal soap treated titanium dioxide 15 Zinc Oxide 3 Petrolatum 1 Sorbitan Sesquiisostearate 1 Triisostearate 1 Glyceryl tri(ethylhexanoate) 1 preservative Moderate Antioxidants Moderate Coloring Materials 8 Pearlescent Agent 8 Food flavors Moderate total 100

Claims

1. A powder cosmetic, characterized in that: Include: (a) at least one metal oxide powder selected from titanium dioxide, zinc oxide and cerium oxide, the average particle size of which is 10 nm or less and which accounts for 5% by mass or more of the total amount of the cosmetic; and (b) Silica.

2. The powder cosmetic according to claim 1, wherein: (a) The amount of the metal oxide blended is 10% by mass or more based on the total amount of the cosmetic.

3. The powder cosmetic according to claim 1 or 2, wherein: (b) The amount of silica blended is 10% by mass or more based on the total amount of the cosmetic.

4. The powder cosmetic according to claim 1 or 2, wherein: (a) The metal oxide powder is titanium dioxide.

5. The powder cosmetic according to claim 1, wherein: The (a) metal oxide powder is a metal oxide powder surface-treated with a metal soap.

6. The powder cosmetic according to claim 5, wherein: The metallic soap comprises aluminum stearate.

7. The powder cosmetic according to claim 1, wherein: The specific surface area of ​​the silica (b) is 160 m 2 / g or above.

8. The powder cosmetic according to claim 1, wherein: The blending amount of the oil component is 10% by mass or less based on the total amount of the cosmetic.

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