JPH08225316A - Spherical inorganic powder - Google Patents

Abstract

PURPOSE: To provide the subject powder having transparency and high light- scattering property and, accordingly, useful as an additive for cosmetics, etc., effective for masking the wrinkles while preventing the white appearance. CONSTITUTION: This spherical inorganic powder has a refractive index of 1.5-2.0, a volume-average particle diameter of 0.1-4μm and a transmitted light scattering ratio of >=70% and a total transmittance of >=80%. The transmitted light scattering ratio and the total transmittance are defined by the formulas, Td/(Tp+ Td)}×100 and (Tp+Td), respectively, wherein Tp is a parallel light transmittance and Td is a scattered light transmittance measured by a haze meter on a thin film produced by uniformly dispersing a specimen in a dispersion medium having a refractive index of 1.4-1.5 at a concentration of 20wt.% and forming a thin film having a thickness of 15μm.

Description

Detailed Description of the Invention

[0001]

The present invention relates to cosmetics, paints, rubbers,
The present invention relates to a light-diffusing spherical inorganic powder which is useful as a compounding component of plastics for making it difficult to see color irregularities and surface irregularities of a base material, or as a matting agent.

[0002]

2. Description of the Related Art Conventionally, white pigments such as zinc oxide and titanium oxide are concealed in cosmetics, paints, etc. in order to hide the difference in brightness due to the uneven color of the base material and the surface irregularities. Used as an agent. In general, polymers such as oils, vehicles, and plastics used in cosmetics and paints have a refractive index in the range of 1.4 to 1.5, and if particles having a refractive index higher than this are mixed, light will be emitted as particles. This is because it is known that a scattering phenomenon occurs at the interface with the vehicle, and the scattering phenomenon by the white pigment is effective in hiding the color unevenness of the substrate. But,
These white pigments have too high a light scattering property due to their refractive index,
Since it is poor in transparency, when it is blended in a cosmetic composition, for example, it may cause whitening or thick makeup.

On the other hand, as an extender pigment which transmits light moderately but refracts light in a complicated manner inside particles and scatters it,
Flake-like porous silica (Japanese Patent Laid-Open No. 63-166819), barium sulfate having a specific plate-like shape (Japanese Patent Laid-Open No. 3-252016), and the like are known. However, with these plate-shaped powders, for example, when blended in cosmetics, they adhere well to the skin, and it is possible to make relatively small irregularities such as spots of color unevenness and pores inconspicuous, but light diffusion Due to the lack of, large wrinkles could not be effectively hidden.

The object of the present invention is to maintain high transparency and high light diffusivity.
It is an object of the present invention to provide a spherical inorganic powder capable of preventing whitening and making wrinkles and the like less noticeable.

[0005]

The inventors of the present invention have found that the scattering angle of light passing through particles is widened by making the particle shape not spherical but spherical particles having an appropriate curvature. The inventors have found that high light diffusivity and transparency can be obtained by controlling the refractive index and particle size to be appropriate, and have completed the present invention.

That is, the gist of the present invention is as follows: (1) Transmitted light scattering rate which is measured under the following conditions, having a refractive index of 1.5 to 2.0, a volume average particle size of 0.1 to 4 μm. Is 70% or more and the total transmittance is 80% or more. A sample is uniformly dispersed at a concentration of 20% by weight in a dispersion medium having a refractive index of 1.4 to 1.5 to form a thin film having a thickness of 15 μm. Formed and measured by a haze meter for parallel light transmittance (Tp) of thin film
And the scattered light transmittance (Td) are measured, and {Td / (Tp + T
d)} × 100 is defined as the transmitted light scattering rate,
The value given by (Tp + Td) is calculated as the total transmittance. (2) The composition is BaSO ₄ , Al ₂ O ₃ .nH ₂ O
(However, n = 0 to 3), and aAl ₂ O ₃ · bSiO ₂
· NH ₂ O (where, a / b = 0.1~100, n / (a
+ B) = 0 to 10), and one or more kinds of spherical inorganic powders described in (1) above, and (3) {(area of circle corresponding to maximum particle size in projected image of particle) / ( The spherical inorganic powder according to (1) or (2) above, wherein the sphericity given by (particle projected area)} × 100 is 100 to 120.

In the present invention, "spherical" of spherical inorganic powder
Means a wide range from a perfect sphere to an ellipse. Specifically, the sphericity given by {(area of circle corresponding to maximum particle size in particle projection image) / (particle projection area)} × 100 is It means 100 to 120. However, from the viewpoint of light diffusibility, a sphericity of 100 to 115 is more preferable. Here, the sphericity is a sphericity index obtained by image-analyzing an electron micrograph of a particle, and specifically, 100 or more particle images from an electron micrograph of powder are analyzed by Nireco's Luzex III image analysis. It is an average value calculated by the shape index calculation program of the device after being taken into the device.

The spherical inorganic powder of the present invention has a refractive index of 1.5.
Is about 2.0, and from the viewpoint of transparency, the refractive index is preferably 1.5 to 1.8.

Examples of the material of the spherical particles having a refractive index within this range include barium sulfate (refractive index 1.64), strontium sulfate (refractive index 1.63), alumina (refractive index varies depending on crystal form, corundum Then 1.77,
1.65 for boehmite, 1.70 for diaspore,
1.57 for gypsite), alumina-silica composite oxide (for example, 1.64 for mullite, 1.66 for sillimanite, and 1.
5 to 1.77). Of these,
The composition is BaSO ₄ , Al ₂ O ₃ .nH ₂ O (however, n
= 0 to 3), and aAl ₂ O ₃ · bSiO ₂ · nH ₂ O
(However, a / b = 0.1 to 100, n / (a + b) = 0
At least one selected from the group consisting of (10) to (10) is preferable from the viewpoint of suppressing the aggregation of powder and facilitating particle size control.

All of the spherical powders made of the above materials have a high light diffusivity, and are therefore excellent in the effect of blurring color unevenness and surface irregularities and the effect of matting.

Further, even if the material has a refractive index of more than 2.0, it can be compounded in a low-refractive-index spherical silica or spherical alumina matrix to obtain an apparent refractive index of 1.5 to 2.0.
Similar to the above, high light diffusivity and transparency can be obtained. Therefore, the refractive index in the present invention includes the apparent refractive index after such compounding. Refractive index is 2.0
Examples of the material exceeding Z are, for example, zinc oxide (refractive index 2.
0), zirconium oxide (refractive index 2.2), barium titanate (refractive index 2.40), strontium titanate (refractive index 2.49), calcium titanate (refractive index 2.40).
35), calcium zirconate (refractive index 2.14), titanium oxide (refractive index 2.52 for anatase, 2.76 for rutile) and the like. These particles usually have a considerably large reflection with particles of 0.1 μm or more, and transparency cannot be obtained, but it can be improved by the above-mentioned compounding.

The volume average particle diameter of the spherical inorganic powder of the present invention is 0.1 to 4 μm, preferably 0.3 to 3.5 μm.
m. If it is less than 0.1 μm or exceeds 4 μm, the light diffusivity is poor and the effect of the present invention cannot be obtained.

The spherical inorganic powder of the present invention has a transmitted light scattering rate of 70% or more, preferably 75 to 99%, measured under the following conditions. When the transmitted light scattering rate is 70% or more, the high light diffusivity causes the
Wrinkles and uneven colors tend to be less noticeable.

The total transmittance measured under the following conditions is 80% or more, preferably 85 to 99%. When the total transmittance is 80% or more, high transparency tends to prevent whitening and the like when blended in cosmetics and the like.

The transmitted light scattering rate and the total transmission rate are measured under the following conditions. A sample is uniformly dispersed at a concentration of 20% by weight in a dispersion medium having a refractive index of 1.4 to 1.5 to form a thin film having a thickness of 15 μm, and a parallel light transmittance (Tp) of the thin film is measured by a haze meter.
And the scattered light transmittance (Td) are measured, and {Td / (Tp + T
d)} × 100 is defined as the transmitted light scattering rate,
The value given by (Tp + Td) is calculated as the total transmittance. Specifically, silicone oil (amino-modified silicone: Toray Silicone SF
8417, refractive index 1.41) and uniformly dispersed in a glass plate with an applicator to form a thin film of 15 μm on a haze meter (HR manufactured by Murakami Color Research Laboratory).
-100 type).

The method for synthesizing the spherical powder of the present invention as described above is not particularly limited, but it can be obtained, for example, by the following synthesizing method. Spherical barium sulphate and spherical strontium sulphate each have a pH in the presence of a complexing agent that forms a complex with barium ion and strontium ion in an aqueous solution (for example, hydroxycarboxylic acid such as citric acid or ethylenediaminetetraacetic acid (EDTA)) Above neutral, water-soluble barium salts (eg barium chloride,
By reacting barium nitrate) with a water-soluble sulfate (eg sodium sulfate, potassium sulfate, etc.), spherical, monodisperse particles can be obtained. The particle size can be controlled by the complexing agent concentration, reaction temperature, reaction concentration, seed crystal addition amount, and the like. Alternatively, fine particles of barium sulfate having a particle size of 0.1 μm or less may be synthesized in advance, and the dispersion may be spray-dried.

Spherical alumina can be synthesized by several methods. First, spherical alumina particles can be easily obtained by spray drying a commercially available alumina sol. The boehmite can be γ
It can be changed to alumina or corundum. Two
The second method utilizes the hydrolysis reaction of aluminum alkoxide. For example, spherical alumina hydrate is obtained by hydrolyzing aluminum sec-butoxide in octanol / acetonitrile. The third method is a uniform precipitation method in which aluminum sulfate is neutralized with urea. In the second and third methods, alumina hydrate is obtained by a precipitation reaction, and it is converted into an anhydride by calcining this. The fourth method is high temperature thermal spraying of granular alumina particles or oxidation of metallic aluminum powder in a high temperature flame.
Due to the high temperature in this method, the obtained alumina crystal form is almost corundum. The particle size can be controlled by the spraying method, the spraying conditions, the concentration of the reaction raw material, the reaction system solvent, the particle size of the raw material powder, and the like.

The spherical alumina-silica composite oxide is synthesized, for example, by spray firing an arbitrary mixture of an alumina raw material liquid and a silica raw material liquid (Chemical Industry (19
92) 586, Journal of Powder Engineering Vol. 30, No. 9
(1993) 614). Alternatively, an arbitrary composition can be synthesized by a wet hydrolysis reaction of a complex of each alkoxide. The particle size can be controlled by a spray method (ultrasonic spray, nozzle spray, etc.) or various spray conditions.

In the above method, except for the high temperature spraying method, a spherical morphology is basically formed as an aggregate of ultrafine particles of 0.1 to 100 nm during the synthesis. Therefore, although it is a porous powder, the specific surface area can be reduced depending on the wet reaction conditions and firing conditions.

In the detailed study of spherical barium sulfate, not only the particle size of the spherical particles but also the specific surface area is an important factor for the light diffusivity. For spherical spherical barium sulfate having a diameter of about 0.5 to 4 μm, the BET specific surface area is 150 m. If it exceeds ² / g, the light diffusivity is significantly reduced. Therefore, those having a BET specific surface area of 100 m ² / g or less are preferable.

The light diffusivity of spherical alumina and spherical alumina-silica composite oxide is affected not only by the particle size of the spherical particles but also by the specific surface area.
Even if the ET specific surface area exceeds 150 m ² / g, some have good light diffusivity. Therefore, the optimum specific surface area value depends on the composition and cannot be determined unconditionally.

When incorporated into cosmetics, the spherical powder of the present invention is treated with silicone, fatty acid soap, or a surface water repellent treatment with an alkyl phosphate ester or the like, as in the case of extender pigments and coloring pigments that are usually used. Alternatively, water / oil repellent treatment with a fluorine compound may be performed. The spherical powder of the present invention does not impair the light diffusibility by these treatments, and can be effectively used as an extender pigment for cosmetics.

[0023]

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The values shown in the table were measured as follows.

(1) Volume average particle diameter The volume average particle diameter is obtained by dispersing a dry powder in a 0.1% by weight aqueous solution of sodium polyacrylate (Kao, Poise 350) and measuring the particle size distribution (Horiba Seisakusho). , LA-70
The volume average particle diameter was determined by the 0 type). (2) Sphericity For the sphericity, 100 or more particle images were taken from an electron micrograph of powder into a Luzex III image analyzer manufactured by Nireco, and an average value was calculated by a shape index calculation program of the device. (3) Transmitted light scattering rate and total transmittance The sample powder was uniformly dispersed in silicone oil (amino-modified silicone: Torre Silicone SF8417, refractive index 1.41) at a concentration of 20% by weight, and this was glass by an applicator. A haze meter (HR-100 type manufactured by Murakami Color Research Laboratory) is formed by forming a thin film of 15 μm in a plate shape.
The parallel light transmittance (Tp) and the scattered light transmittance (Td) of the thin film are measured by the following method: {Td / (Tp + Td)} × 100
The value given by was calculated as the transmitted light scattering rate, and the value given by (Tp + Td) was calculated as the total transmittance.

Example 1 (Spherical barium sulfate) In a 2 L separable flask, a mixed aqueous solution of sodium citrate and barium chloride was stirred, and an aqueous sodium sulfate solution having an equimolar amount to barium chloride was added thereto within 10 seconds. did. The total concentration of this reaction solution is 0.008mo each
1 / L, 0.007 mol / L, and 0.007mo
It was 1 / L. The reaction liquid became cloudy after an induction period of several seconds to several tens of seconds after the addition of the aqueous sodium sulfate solution. After stirring for 1 hour, the mixture was filtered, washed, and dried at 100 ° C. In addition, in order to obtain spherical barium sulfate having various particle diameters, the sodium citrate concentration was changed, and seed crystals of spherical barium sulfate were added in advance before the reaction. Table 1 shows the experimental conditions and the physical properties of the obtained spherical barium sulfate.

[0026]

[Table 1]

As can be seen from Table 1, the light diffusivity was highest in the range of 0.9 to 2.3 μm for the particle size of spherical barium sulfate.

A typical electron micrograph of the obtained particles is shown in FIG. As can be seen from FIG. 1, the spherical barium sulfate obtained by this method was a powder that was nearly spherical and was monodisperse and did not aggregate.

Example 2 (spherical alumina) Nissan Chemical Industries Alumina sol-520 (20 wt% sol) was diluted with ion-exchanged water to make 1 wt% sol, which was N ₂ 4 L
Ultrasonic spray drying was performed at a drying temperature of 600 ° C. under a flow rate of / min. Physical properties of the obtained spherical alumina are shown in Table 1 and an electron micrograph thereof is shown in FIG. From the X-ray diffraction and thermal analysis of the obtained powder, the crystal phase was mainly γ-Al ₂ O ₃ and the composition was Al ₂ O ₃ .0.2H ₂ O.

Example 3 (spherical alumina) A mixed aqueous solution of aluminum sulfate and urea was stirred in a 2 L separable flask. Each concentration is 0.001m
ol / L and 0.075 mol / L. This solution was heated at 100 ° C for 2 hours, filtered, washed with water, and then heated to 100 ° C.
Dried in. Table 1 shows the physical properties of the obtained spherical alumina. The composition of the obtained powder was Al ₂ O ₃ · 1.7H.
It was ₂ O.

Example 4 (Synthesis of Spherical Alumina-Silica Composite Oxide) Diluents of alumina sol (Nissan Chemical Co., Ltd., alumina sol-520) and silica sol (Nissan Chemical Co., Ltd., Snowtex O) were mixed at an arbitrary ratio. , Ultrasonic spray drying was performed. Drying and calcination after drying were performed at various temperatures to synthesize various spherical particles. The physical properties are shown in Table 2.

[0032]

[Table 2]

Comparative Examples 1 to 5 Plate-shaped barium sulfate was used as Comparative Example 1, spherical barium sulfate having a large particle size was used as Comparative Example 2, spherical alumina having a large particle size was used as Comparative Example 3, and refractive index was used as Comparative Example 4. Table 3 shows a large spherical titanium oxide and a spherical silica having a small refractive index as Comparative Example 5, together with the values of transmitted light scattering rate and total transmittance.

[0034]

[Table 3]

From the results shown in Tables 1 and 2, it was found that the spherical inorganic powder of the present invention can obtain a high transmitted light scattering rate and a high total transmittance. On the other hand, from the results of Table 3, tabular barium sulfate (Comparative Example 1), spherical barium sulfate having a large particle size (Comparative Example 2), spherical alumina having a large particle size (Comparative Example 3), and small refractive index With spherical silica (Comparative Example 5),
It was found that neither of them could obtain a sufficient transmitted light scattering rate. Further, spherical titanium oxide having a large refractive index (Comparative Example 5)
Then, the total transmittance was extremely low.

[0036]

EFFECTS OF THE INVENTION The spherical inorganic powder of the present invention has high light diffusivity while maintaining transparency. Therefore, when blended in cosmetics or the like, it prevents whitening and makes wrinkles less noticeable. be able to. Therefore, it can be suitably used especially for cosmetics and the like.

[Brief description of drawings]

FIG. 1 is a photograph showing the particle structure of spherical barium sulfate obtained in Example 1.

FIG. 2 is a photograph showing the particle structure of the spherical alumina obtained in Example 2.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // A61K 7/00 A61K 7/00 BL

Claims (3)

[Claims] 1. A refractive index of 1.5 to 2.0, a volume average particle size of 0.1 to 4 μm, a transmitted light scattering rate of 70% or more, and a total transmittance measured under the following conditions. A spherical inorganic powder having a content of 80% or more. A sample is uniformly dispersed at a concentration of 20% by weight in a dispersion medium having a refractive index of 1.4 to 1.5 to form a thin film having a thickness of 15 μm, and a parallel light transmittance (Tp) of the thin film is measured by a haze meter.
And the scattered light transmittance (Td) are measured, and {Td / (Tp + T
d)} × 100 is defined as the transmitted light scattering rate,
The value given by (Tp + Td) is calculated as the total transmittance. 2. The composition is BaSO ₄ , Al ₂ O ₃ .nH.
₂ O (however, n = 0 to 3) and aAl ₂ O ₃ · bSi
O ₂ · nH ₂ O (however, a / b = 0.1-100, n /
The spherical inorganic powder according to claim 1, which is one or more selected from the group consisting of (a + b) = 0 to 10). 3. The spherical inorganic material according to claim 1, wherein the sphericity given by {(area of circle corresponding to maximum particle size in particle projection image) / (particle projected area)} × 100 is 100 to 120. powder.