JP2001098186A - Flaky pigment and method for preparing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flaky pigment having an excellent soft focusing effect, extending effect and ultraviolet ray-shielding effect, and further having appropriate whiteness. SOLUTION: This flaky pigment is prepared by adhering spherical silica particles having an average particle diameter of 20-500 nm to the surface of a flaky substrate having an average particle diameter of 0.5-10 μm, and further covering the surface of the silica particle-adhered substrate with ultra fine particles of titanium dioxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a flaky pigment for cosmetics and resins. In detail, the present invention has an advanced soft focus effect, which is a skin wrinkle concealing effect particularly required as a cosmetic, a good extensibility effect on the skin, and further has an ultraviolet shielding effect and an appropriate whiteness. The present invention relates to a flaky pigment and a method for producing the same.

[0002]

Heretofore, flaky substances such as natural mica, synthetic mica, mica titanium, talc, sericite and boron nitride have been used as fillers for extenders or resins for cosmetics. However, when they are used for cosmetics, they do not satisfy the required properties such as wrinkle hiding effect, ultraviolet ray shielding effect, whiteness, etc., while having adhesiveness to skin and extensibility.

As a pigment having good extensibility on the skin,
Although extenders such as talc and boron nitride having no luster are commercially available, it has been confirmed that talc contains asbestos, and its use as a cosmetic pigment has recently been restricted. Pigments made of boron nitride are not suitable for cosmetic use because boron nitride is expensive and may contain unreacted boric acid in the raw material. Similarly, as pigments having good extensibility, flaky bismuth oxychloride and titanium oxide-coated mica are used in some cosmetics because of their good feel and extensibility on the skin,
Bismuth oxychloride is too glossy and unnatural, which limits its use in foundations and the like.

Further, as a pigment having improved extensibility, a pigment having silica particles of 0.05 to 50 μm adhered to a mica surface or a mica titanium surface has been proposed (DE3).
922178/1989: JP-A-3-45660). This pigment aims to improve the extensibility due to the ball bearing effect of the silica particles, but has the disadvantage of poor adhesion to the skin, and also has sufficient adhesion of the silica particles to the mica surface. However, it is difficult to obtain a sufficient extensibility effect because the peeling is likely to occur at a stage before use after the production and before use. Further, the diameter of the attached silica particles is 0.0
Soft focus effect (Naoki Nakamura, et al, XIVth IF.
S. C. C. Congress, Barcelona, 1986, Vol. 1, P51-6
3) was difficult to expect.

Further, as a pigment obtained by improving the above-mentioned flaky pigment coated with silica particles, there has been proposed a pigment in which spherical silica particles are improved in adhesion to mica by using organic silica such as 4-ethyl silicate or sodium silicate. (WO9
2/03119). This pigment is said to have improved adhesion and extensibility effects on the skin and also has a soft focus effect. The silica particles disclosed herein have a diameter of about 5 μm or less, preferably 0.05 to 3 μm. Even with this particle diameter, the silica particles are large, so that special treatment conditions (for adhesion) Is necessary to determine the dielectric constant and ion concentration of the dispersion liquid), which is disadvantageous in the production method. In addition, since this pigment has low whiteness, when it is used as a cosmetic, there is also a problem that titanium dioxide or the like must be separately added for the purpose of increasing it.

Further, the pigments coated with the above-mentioned two silica particles use flaky substrates having a large particle diameter of 1 to 500 μm and about 30 μm (see Examples), respectively. Too big to use,
The slip on the skin was not good.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a wrinkle hiding effect (soft focus effect), an extensibility effect (with a low coefficient of friction), an ultraviolet shielding effect and an appropriate whiteness. Flaky pigments.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventors have made spherical silica particles adhere to the surface of a flaky substrate, and furthermore, coated ultrafine titanium dioxide on the surface of the flaky substrate with the spherical silica particles adhered thereto. It has been found that the above problems can be solved by coating, and the present invention has been completed. That is, the present invention has an average particle diameter of 0.5 to 10
The average particle diameter is 20 to 500 n on the flaky substrate surface
The present invention relates to a flaky pigment obtained by adhering spherical silica particles of m in diameter and coating the surface of the flaky substrate with the spherical silica particles with ultrafine titanium dioxide. Further, the present invention provides that the amount of the spherical silica particles is 3 based on the spherical silica-adhered flaky substrate.
It relates to the flaky pigment, which is 0% by weight or less. Furthermore, the present invention relates to the above flaky pigment, wherein the amount of the fine titanium dioxide is 1 to 50% by weight based on the flaky pigment, and the fine particle titanium dioxide has a particle diameter of 50 nm or less. The present invention also provides an aqueous suspension of a flaky substrate by adding an alkaline aqueous solution to alkalinity, adding a suspension of spherical silica particles under heating and stirring to the alkaline suspension, and then adding a predetermined amount of a part of the suspension. The pH is adjusted to 1.5 to
4.0, spherical silica particles were adhered to the flaky substrate surface, and the remaining titanium salt aqueous solution was added while maintaining the pH at 1.5 to 4.0 using the titanium salt aqueous solution and the alkali aqueous solution. The present invention relates to a method for producing the flaky pigment, wherein the pH is raised to 5 using an alkaline aqueous solution, a solid substance is collected by filtration, washed with water, dried, and calcined. Furthermore, the present invention relates to a cosmetic containing the flaky pigment. The present invention also relates to the use of the flaky pigment as a filler.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The material of the flaky substrate used in the present invention may basically be either natural or synthetic, but it is highly safe for use as a pigment and has high heat resistance. Durable ones are preferred. Specifically, natural mica, synthetic mica, titanium mica (a flaky mica coated with titanium oxide, the same throughout the present specification), talc,
Examples include sericite, kaolin, and flaky alumina (including those coated with titanium oxide), and preferably natural mica, synthetic mica, titanium mica, talc, and sericite. Among these, natural mica, synthetic mica and mica titanium are more preferred.

[0010] The shape of these flaky substrates is such that the average particle diameter of the flaky substrate is in order to maintain a low coefficient of friction, which is desirable for use as a cosmetic, and to prevent powder agglomeration. 5-10 μm, preferably 2-8 μm
m are recommended. When particles smaller than 0.5 μm are used, the particles obtained in the present invention are liable to agglomerate and cannot function as primary particles, which is not preferable. Of course,
As a result, improvement in extensibility and soft focus effect cannot be expected. On the other hand, when a pigment having a thickness of 10 μm or more is used, it is difficult to obtain a pigment having good slip on the skin. Those having these shapes can be easily obtained from natural products or synthetic products by combining ordinary pulverization and classification for those skilled in the art. Further, some of the synthesized products can be controlled to have a predetermined size within the above range by controlling crystal growth by a synthesis method such as a hydrothermal method or a molten salt method. Commercially available particles having the above-mentioned particle size can also be used easily. Among these flaky substrates, natural mica or one coated with titanium oxide (titanium mica) is particularly suitable as the substrate because of its low cost and availability.

The spherical silica particles used in the present invention can be easily obtained on the market. The particle size is the size of the flaky substrate (0.5 to 10 μm).
m), the average particle size is determined by the relationship with the target low coefficient of friction and the like.
Those having a thickness of 500 nm, preferably 40 nm to 400 nm are suitable. If the particle diameter of the spherical silica is too large, the adhesion of the spherical silica particles to the flaky substrate is reduced, and as a result, the extensibility effect cannot be obtained. As a result, the soft focus effect cannot be obtained. On the other hand, if the particle diameter is too small, the spherical silica particles have good adhesion to the flaky substrate surface, but the extensibility is not improved and the friction coefficient is not low. As a tendency, when using a large particle diameter of the flaky substrate particles in the above range, it is preferable to use a large particle diameter of the spherical silica particles also in the above range, the flaky substrate itself As the particle size decreases, spherical silica particles having a smaller particle size will be used accordingly. As an effect, the larger the particle diameter of the spherical silica, the lower the coefficient of friction to the flaky substrate, the greater the effect, and as a result, the slipperiness is improved. Therefore,
When a spherical silica particle having a large diameter is used, the effect of lowering the friction coefficient is exhibited with a small amount of coating. Conversely, when the diameter of the spherical silica particle is reduced, the effect of decreasing the friction coefficient is less likely to appear.

That is, as the amount of adhered spherical silica particles gradually increases, the coefficient of friction decreases at the beginning and reaches a minimum, and thereafter the coefficient of friction gradually increases.
This tendency becomes more remarkable as the diameter of the spherical silica particle increases, and the smaller the diameter of the spherical silica particle, the more difficult it is for this minimum to appear. This is presumably because, when spherical silica particles having a small particle diameter are used, the apparent contact area with the flaky substrate increases because the unit surface area is large, and the friction coefficient increases. Further, it is considered that the reason why the friction coefficient gradually increases after the decrease in the friction coefficient is minimized is that the adhered spherical silica particles aggregate and the contact area between the silica particles increases. In consideration of such a phenomenon, in the present invention, the spherical silica particles having an average particle diameter in the range of 20 to 500 nm are used in consideration of the extensibility and the soft focus effect for the purpose of reducing the adhesion amount to 30% by weight or less. Will be selected appropriately. In the present invention, the friction coefficient of the prepared pigment was measured using "KES-SE-DC", a friction tester manufactured by Kato Tech Co., Ltd., and "MIU" (friction coefficient) measured according to the measurement conditions. The smaller the value, the smaller the friction coefficient, that is, the greater the extensibility effect.

For example, as a flaky substrate, the average particle diameter is about 5 μm.
m is used, the average particle diameter of the spherical silica is 7
An amount of 2 to 30% by weight is suitable for 0 to 500 nm, and an amount of 2 to 20% by weight for 40 to 50 nm. These spherical silica particles are commercially available and can be easily obtained (for example, Snowtex (Nissan Chemical) series (trade name “Snowtex ZL”,
"Snowtex 3040" and silica for column chromatography (manufactured by Merck). The flaky pigment according to the present invention is a pigment in which titanium dioxide is further coated on the flaky substrate surface to which the above-mentioned spherical silica particles are adhered. As a result, the adhesive force of the spherical silica particles to the flaky substrate can be increased, and the ultraviolet shielding effect and the whiteness can be improved. The coating treatment with titanium dioxide also has the effect of reducing the drawback of a decrease in the adhesion of the silica particles to the substrate when the diameter of the spherical silica particles is increased.

As the raw material of titanium dioxide in the present invention, any titanium salt compound can be used. Among them, acidic salts such as titanium tetrachloride, titanyl sulfate, titanyl nitrate and the like are preferably used for the purpose of lowering the pH in the production process. In the present invention, by replacing a part of the titanium salt aqueous solution to be added with another zinc salt solution or a cerium salt solution, the ultraviolet shielding ability or the ultraviolet shielding wavelength region can be appropriately changed.

The method for producing the flaky pigment of the present invention includes:
The following method is adopted. First, an aqueous suspension of a flaky substrate is prepared, and an aqueous alkali solution is added thereto while stirring with heating (about 70 ° C.) until the pH of the suspension becomes 10 or more, preferably 12 or more. The reason why the pH is made alkaline is to remove the flaky substrate from the isoelectric point (the pH at which the surface charge becomes zero and agglomerate easily), repel the flaky substrates and bring them into a dispersed state. Therefore, it is necessary to appropriately change the pH for making this dispersion state according to the isoelectric point of the flaky substrate species. For example, when natural mica is used as the flaky substrate, pH of 12 is usually appropriate. Naturally, when a flaky substrate having a high isoelectric point is used, it is necessary to increase the pH in order to ensure this dispersibility. Conversely, when the isoelectric point is lower than that of natural mica,
Is low, and a pH of around 10 is generally employed.

Next, spherical silica particles are added to the flaky substrate suspension under the alkaline region. Flaky substrate,
In a state where the silica particles and the spherical silica particles are sufficiently dispersed, the titanium salt aqueous solution is added with stirring to adjust the pH to 1.5 to 4.
0, especially 1.5 to 2.5. The flaky substrate and the spherical silica particles adhere to each other by bringing the surface charges of the flaky substrate and the spherical silica particles closer to each other's isoelectric point (reducing the repulsion). This pH is for allowing the particles to adhere to each other at a value close to both the isoelectric point of the flaky substrate and the isoelectric point of the spherical silica particles (a state in which the absolute values of the surface charges are small), and the subsequent addition of titanium salt This is based on the pH of the decomposition reaction. At this time, by adding a solution of a tin salt or the like and using it as a rutile agent, the crystal form of titanium dioxide in the final product can be made into a rutile type instead of a normal anatase type. Subsequently, the remaining predetermined amount of an aqueous solution of a titanium salt is added simultaneously with an aqueous alkali solution while maintaining the pH constant, whereby a titanium hydrolyzate, a so-called titanium hydrate (hydroxide, oxide crystal water adduct, hydrated Substance or oxide). Further, at this time, a part of the remaining predetermined amount of the aqueous titanium salt solution is heated and hydrolyzed in advance to form a rutile type coating, and the titanium dioxide crystal form of the final product is converted to a rutile type manufacturing method. Can also be taken.

The amount of the titanium salt used is adjusted to a pH of 1.5 to
The amount is 1 to 50% by weight in terms of titanium oxide with respect to the final product, including the amount of reducing to 4.0, particularly 1.5 to 2.5. This is because the titanium salt is hydrolyzed and adheres to the surface of the flaky substrate and the spherical silica, thereby suppressing the separation of the spherical silica particles and increasing the ultraviolet shielding effect and the whiteness. These effects are
If it is less than 1%, it cannot be demonstrated, and if it is more than 50%,
Since the ratio of the spherical silica particles is relatively reduced, the soft focus effect for concealing wrinkles exhibited by the spherical silica particles, which is the main object of the present invention, is reduced. In the hydrolysis reaction of the titanium salt, the production conditions are selected so that the particle size of titanium oxide as a final product is 50 nm or less, particularly 30 nm or less. The particle size of the titanium oxide is appropriately selected depending on the coefficient of friction (MIU). These production conditions can be easily determined by appropriately selecting production conditions such as the addition speed, the rotation speed of the stirring blade, and the temperature in the conventional pigment production. After the dropping of the predetermined amount of the aqueous solution of the titanium salt under a constant pH in this manner, the pH is further adjusted to about 5 using an aqueous alkaline solution, and the coated pigment in the reaction solution is filtered and desalted. After washing with water and drying at normal temperature, finally, about 600-9
Fired at 00 ° C.

The flaky pigment produced by the above method has a soft focus effect, an extensibility effect (low MIU),
It exhibits an ultraviolet shielding effect, has an appropriate whiteness, and has particularly excellent properties as a pigment for cosmetics. In addition, the flaky pigment of the present invention, as a filler for resin,
Alternatively, it can also be used as a paint for general pigment use, a printing ink, and the like.

Next, the present invention will be described in more detail with reference to examples. Note that the present invention is not limited to the following examples.

[0020]

EXAMPLE 1 145 g of mica having an average particle size of 5 μm is suspended in 1400 ml of water and heated to 70 ° C. with stirring.
About 3.0 ml of a 32% by weight aqueous sodium hydroxide solution was added to the aqueous suspension to adjust the pH to 12. To this suspension, 40 g of a 40% by weight colloidal silica particle suspension (trade name “Snowtex ZL”, average particle diameter 70 nm, manufactured by Nissan Chemical Industries) is quantitatively supplied at a rate of 5 ml / min while stirring. Thereafter, about 100 ml of an aqueous solution of titanium tetrachloride having a concentration of 436 g / l was separately prepared.
Dispense at 5 ml / min and lower the pH of the aqueous suspension from 12 to 2. The addition of the acidic component of titanium tetrachloride causes the spherical silica colloid particles to adhere to the mica surface. The remaining aqueous solution of titanium tetrachloride is similarly supplied to the aqueous suspension while maintaining the pH at 2 using an aqueous solution of sodium hydroxide having a concentration of 32% by weight. After the supply of the entire amount of the titanium tetrachloride aqueous solution is completed, the pH is further increased to 5 using an aqueous solution of sodium hydroxide having a concentration of 32% by weight. The back was taken, washed with deionized water, dried at 110 ° C., and finally calcined at 700 ° C. to obtain a target flaky pigment. The obtained flaky pigment was composed of 9.4% by weight of spherical silica particles and 11.9% by weight of titanium oxide, and the particle diameter of the coated titanium oxide was SEM.
(Scanning electron microscope) The result of observation of the photograph was 30 nm or less.

Example 2 200 g of mica having an average particle size of 5 μm was suspended and stirred in 2000 ml of water, and about 5.0 ml of a 32% by weight aqueous sodium hydroxide solution was added to the aqueous suspension.
Let H be 12. A 40% by weight suspension of colloidal silica particles (trade name “Snowtex 3040”,
56 g of an average particle diameter of 300 nm (manufactured by Nissan Chemical Industries) is supplied at a constant rate of 1.0 ml / min while stirring. Thereafter, the mixture was heated to 70 ° C., and about 68 ml of an aqueous titanium tetrachloride solution having a concentration of 410 g / l was separately prepared.
Dispense at 0 ml / min and lower the pH of the aqueous suspension from 12 to 2. The addition of the acidic component of titanium tetrachloride causes the spherical silica colloid particles to adhere to the mica surface. The remaining aqueous solution of titanium tetrachloride is similarly supplied to the aqueous suspension while maintaining the pH at 2 using an aqueous solution of sodium hydroxide having a concentration of 32% by weight. After the supply of the entire amount of the titanium tetrachloride aqueous solution is completed, the pH is further increased to 5 using an aqueous solution of sodium hydroxide having a concentration of 32% by weight. The back was taken, washed with deionized water, dried at 110 ° C., and finally calcined at 700 ° C. to obtain a target flaky pigment. The obtained flaky pigment was composed of 9.6% by weight of spherical silica particles and 5.0% by weight of titanium oxide.
It was a thing. As a result of observing an SEM (scanning electron microscope) photograph (FIG. 2), the particle diameter of titanium oxide was 50 nm or less. It was also confirmed that the spherical silica particles adhered to the mica surface, and that the titanium oxide adhered to both the mica surface and the spherical silica surface.

1) Measurement of Color Tone: Preparation of Test Paper The flaky pigment of the present invention obtained in Examples 1 and 2 and 1 g of each sample shown in the following table were solid content of 20% by weight.
Was added to 9 g of a vinyl chloride-based medium, and the mixture was stirred and mixed. At 20, a test paper applied to a black-and-white concealing rate test paper was prepared, and the following color tone was measured using this test paper.

Measurement of Soft Focus The diffuse reflectance (Y) of the test paper prepared above on white was measured by using a three-dimensional spectroscopic variable-angle color difference meter GC-2000 manufactured by Nippon Denshoku Industries Co., Ltd.
Using a white diffuse reflectance standard plate at 45 ° incidence angle and 4
When the light receiving angle was 5 °, the incident light source was set to 45 ° incident angle, and the light receiving angle of the light receiving light source was changed by 5 °, and the measurement was performed. The result is shown in FIG. In FIG. 1, the horizontal axis indicates the light receiving angle, and the vertical axis indicates the reflection intensity. Y (−45 ° / 30 °) means that light is incident from an angle of 45 ° with respect to the normal, and the reflection intensity of the reflected light at an angle of 30 ° with respect to the normal. From FIG. 1, it was confirmed that the pigment prepared in Example 1 had a lower reflectance of 45 ° / 45 ° specular reflection light than mica, indicating that the soft furcas effect was strong. In addition,
In the table below, (-45 ° / 30 °), (-45 ° / 45 °
°) and (−45 ° / 60 °).

Whiteness: 100-[(100-L) ² +
a ² + b ² ] ^1/2 Calculated by the formula: Here, the L, a, and b values were measured using a three-dimensional color difference meter GC-3000A manufactured by Nippon Denshoku Industries Co., Ltd. Concealment ratio: ΔY (−45 ° / 45 °) (on black paper) / Y
(-45 ° / 45 °) (on white paper) Value calculated by the formula of × 100

2) Measurement of UV shielding properties: 0.5 g of a sample was added to 9.5 g of a vinyl chloride medium having a solid content of 20% by weight, and the mixture was stirred and mixed. The obtained dispersion was glass-coated using an applicator having a thickness of 120 μm. Apply on board. After drying, the transmittance of an ultraviolet wavelength region of 300 nm (UVB) was measured using a spectrophotometer U-3000 manufactured by Hitachi, Ltd. using the obtained coating film. Therefore, a smaller numerical value indicates a higher UV shielding property.

The following table shows the physical properties of each sample measured by the above method.

[Table 1] In the table, each sample shows the following contents. Mica: Average particle size is 5 μm (the same as the raw material mica used in Example 1). Talc: Asada Milling Talc-L, average particle size 6 μm BLF: bismuth oxychloride (trade name: manufactured by Rona)
(Biron LF2000) MIU: Coefficient of friction ("Fractive sensation tester, KES-SE-
DC ", manufactured by Kato Tech Co., Ltd.)

As described above, the physical property values of each sample shown in the table and FIG.
As is apparent from the above, the flaky pigment Example 1 of the present invention
When the incident angle of light is 45 °, the measurement angle (reflection angle) is 30.
Even if the angles were changed to 45 °, 45 °, and 60 °, the change in the reflection intensity was small, and it was confirmed that the so-called soft focus effect was good. It also has hiding power and whiteness, and it has been confirmed from MIU measurement results that the sliding friction coefficient is low and the extensibility is good, and that the ultraviolet shielding effect is also excellent. Further, in Example 2 in which the average particle size of the silica particles was larger than that in Example 1, the soft focus effect was equivalent to that of Example 1, and the extensibility and the ultraviolet ray shielding effect were superior to Example 1.

[0028]

[Application example] Application example 1. Use as Cosmetic Using the flaky powder obtained in Example 1, a cosmetic (compact powder) having the following composition was prepared. Composition Flaky pigment of Example 1 25 parts by weight Color pigment 5 parts by weight Lanolin 3 parts by weight Isopropyl myristate proper amount Magnesium stearate 2 parts by weight Talc 50 parts by weight

[0029] 2. Use as filler for plastic Composition High density polyethylene resin (pellet) 100 parts by weight Flaky pigment obtained in Example 1 1 part by weight Magnesium stearate 0.1 part by weight Zinc stearate 0.1 part by weight Is dry-blended and injection-molded.

[0030]

As described above, the flaky pigment according to the present invention has a soft focus effect and a coefficient of friction (MI).
U) is small, and furthermore, has appropriate whiteness and ultraviolet shielding performance, and exhibits particularly excellent properties as a pigment for cosmetics.

[Brief description of the drawings]

FIG. 1 is a reflected light distribution diagram measured for the flaky pigment and mica of the present invention.

FIG. 2 is a scanning electron micrograph of a flaky pigment of the present invention (Example 2).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 101/00 C08L 101/00

Claims (6)

[Claims] 1. A method for adhering spherical silica particles having an average particle diameter of 20 to 500 nm to a surface of a flaky substrate having an average particle diameter of 0.5 to 10 μm, and further comprising an ultrafine titanium dioxide on the surface of the flaky substrate having the spherical silica particles adhered thereto. A flaky pigment coated with 2. The flaky pigment according to claim 1, wherein the amount of the spherical silica particles is 30% by weight or less based on the flaky silica-adhered flaky substrate. 3. The flaky pigment according to claim 1, wherein the amount of the fine titanium dioxide is 1 to 50% by weight based on the flaky pigment, and the fine particle titanium dioxide has a particle diameter of 50 nm or less. 4. An aqueous alkali solution is added to an aqueous suspension of a flaky substrate to make it alkaline, a spherical silica particle suspension is added to said alkaline suspension under heating and stirring, and a predetermined amount of titanium is added. A salt aqueous solution is dropped to adjust the pH to 1.5 to 4.0, spherical silica particles are adhered to the surface of the flaky substrate, and the remaining titanium is kept at 1.5 to 4.0 using an alkaline aqueous solution. After the salt aqueous solution is added, the pH is raised to 5 using an alkaline aqueous solution, and the resulting solid is collected by filtration, washed with water, dried, and fired.
The method for producing a flaky pigment according to any one of claims 1 to 3. 5. A cosmetic comprising the flaky pigment according to any one of claims 1 to 3. 6. Use of the flaky pigment according to any one of claims 1 to 3 as a filler.