KR-20260066802-A - Zinc oxide powder, oil-dispersible cosmetic composition and cosmetic

Abstract

The present invention provides zinc oxide powder capable of producing a cosmetic that exhibits excellent visible light transmittance and UV shielding ability when applied to the skin, an oil-dispersible cosmetic composition in which the zinc oxide powder is blended, and a cosmetic. The zinc oxide powder of the present invention is characterized by having a number distribution D 50 of 100 to 200 nm obtained from a transmission electron microscope image, an aspect ratio of 1.1 to 1.4, and a crystallite diameter of 70 to 200 nm obtained from an X-ray diffraction spectrum. Additionally, the oil-dispersible cosmetic composition of the present invention is characterized by the zinc oxide powder of the present invention being dispersed in oil. The oil-in-water emulsion cosmetic and the oil-in-water emulsion cosmetic of the present invention are characterized by having the oil-dispersible cosmetic composition of the present invention blended or the zinc oxide powder of the present invention blended. The powder cosmetic of the present invention is characterized by having the zinc oxide powder of the present invention blended.

Inventors

• 미토 šœ스케
• 오사키 다이스케

Assignees

• 데이카 가부시키가이샤

Dates

Publication Date

20260512

Application Date

20241030

Priority Date

20231031

Claims (13)

1. Zinc oxide powder having a number distribution D 50 of 100–200 nm obtained from a transmission electron microscope image, an aspect ratio of 1.1–1.4, and a crystallite diameter of 70–200 nm obtained from an X-ray diffraction spectrum.
2. In Article 1, Zinc oxide powder having a number distribution D 10 of 100–200 nm obtained from a transmission electron microscope image.
3. In Article 1, Zinc oxide powder having a ratio of light transmittance at wavelength 550 nm: Tt550 and light transmittance at wavelength 370 nm: Tt370, obtained using a spectral transmittance curve obtained from a film formed with nitrocellulose: Tt550/Tt370, of 3.5 or greater.
4. In Paragraph 3, Zinc oxide powder with a Tt370 of 24 or less.
5. In Paragraph 3, Zinc oxide powder with a Tt550 of 80 or higher.
6. In Article 1, Surface-treated zinc oxide powder.
7. In Article 6, Zinc oxide powder surface-treated with at least one surface treatment agent selected from the group consisting of silicone oil, fatty acids, and alkylsilanes.
8. An oil-dispersible cosmetic composition in which zinc oxide powder according to any one of claims 1 to 7 is dispersed in oil.
9. A water-in-oil emulsion cosmetic formulated with the oil-dispersible cosmetic composition of claim 8.
10. An oil-in-water emulsion cosmetic formulated with the oil-dispersible cosmetic composition of claim 8.
11. A water-in-oil emulsion cosmetic formulated with zinc oxide powder according to any one of claims 1 to 7.
12. An oil-in-water emulsion cosmetic formulated with zinc oxide powder according to any one of claims 1 to 7.
13. A powder cosmetic formula incorporating zinc oxide powder according to any one of claims 1 to 7.

Description

Zinc oxide powder, oil-dispersible cosmetic composition and cosmetic The present invention relates to zinc oxide powder capable of producing a cosmetic that exhibits excellent visible light transmittance and ultraviolet shielding ability when applied to the skin, an oil-dispersible cosmetic composition using said zinc oxide powder, and a cosmetic. Various cosmetics applied to the skin, such as sunscreens, sometimes contain inorganic powders such as zinc oxide. Meanwhile, recently, there has been a trend requiring the use of so-called non-nano zinc oxide with a particle size of 100 nm or more, as there is a concern that fine zinc oxide powder may penetrate into the skin when a cosmetic product containing zinc oxide powder with a small particle size is applied (Patent Document 1 et al.), and a method for manufacturing zinc oxide powder with a large particle size is also being reviewed (Patent Document 2 et al.). Zinc Oxide Powder The zinc oxide powder of the present invention has a number distribution D 50 (particle size at 50% cumulative frequency based on number. Hereinafter referred to simply as “D 50 ”) obtained from a transmission electron microscope (TEM) image of 100 nm or more and 200 nm or less, an aspect ratio of 1.1 or more and 1.4 or less, and a crystallite diameter (hereafter referred to simply as “crystallite diameter”) obtained from an X-ray diffraction spectrum of 70 nm or more and 200 nm or less. The zinc oxide powder of the present invention corresponds to so-called non-nano zinc oxide and is a powder with a D 50 of 100 nm or more. That is, "non-nano zinc oxide" as used in this specification refers to zinc oxide powder with a D 50 of 100 nm or more. As described above, zinc oxide of this size has lower ultraviolet shielding ability compared to zinc oxide of a smaller size, and when made into a cosmetic, it reduces the transmittance of visible light, so, for example, when this cosmetic is applied to the skin, it is prone to causing a white cast. In the zinc oxide powder of the present invention, the upper limit of D 50 is restricted, and at the same time, the aspect ratio and crystallite diameter are within a specific range, so that when incorporated into a cosmetic product, for example, the visible light transmittance and ultraviolet shielding ability can be increased when the cosmetic product is applied to the skin. As described above, zinc oxide powder has a D 50 of 100 nm or more, but if the D 50 is excessively large, the visible light transmittance of the formulated cosmetic is reduced when applied to the skin, and the ultraviolet shielding ability is also reduced. Therefore, from the perspective of enabling the manufacture of a cosmetic that exhibits good visible light transmittance and ultraviolet shielding ability when applied to the skin, it is preferable that the D 50 of the zinc oxide powder be 200 nm or less, more preferable that it be 195 nm or less, and even more preferable that it be 190 nm or less. In addition, for zinc oxide powder, it is preferable that the number distribution D 10 (particle size at 10% cumulative frequency based on number. Hereinafter, it may simply be referred to as "D 10 ") obtained by TEM image is 100 nm or more and 200 nm or less, more preferable that it is 100 nm or more and 160 nm or less, and even more preferable that it is 100 nm or more and 135 nm or less. In addition, regarding zinc oxide powder, it is desirable to have an aspect ratio of 1.4 or less and 1.1 or more, and more desirable to have an aspect ratio of 1.2 or more, from the perspective of securing excellent UV shielding ability and maintaining a good balance between this UV shielding ability and visible light transmittance when the formulated cosmetic is applied to the skin. Furthermore, if the crystallite diameter of the zinc oxide powder is excessively small, the visible light transmittance is reduced, for example, when the formulated cosmetic is applied to the skin. Therefore, from the perspective of increasing the visible light transmittance when the formulated cosmetic is applied to the skin and maintaining a good balance between this visible light transmittance and ultraviolet shielding ability, the crystallite diameter of the zinc oxide powder is 70 nm or more. However, if the crystallite diameter of the zinc oxide powder is excessively large, the ultraviolet shielding ability is reduced. Therefore, from the perspective of securing excellent ultraviolet shielding ability and maintaining a good balance between this ultraviolet shielding ability and the visible light transmittance when the formulated cosmetic is applied to the skin, it is preferable that the crystallite diameter of the zinc oxide powder be 200 nm or less, more preferable that it be 180 nm or less, and even more preferable that it be 160 nm. The D 50 , D 10 , and aspect ratio of the zinc oxide powder referred to in this specification are values obtained by the following method. From an image [number of particles (pri