JPH0587545B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND ART AND PROBLEMS The present invention relates to an ultraviolet shielding pigment formed by coating the surface of mica with fine particles of titanium dioxide. Conventionally, sunscreen cosmetics have used organic ultraviolet absorbers and inorganic powders such as titanium dioxide and zinc oxide as ultraviolet shielding substances, but organic ultraviolet absorbers have not been safe for the skin or There are problems with the stability of the system in which it is used, and inorganic powders such as titanium dioxide have strong hiding power and strong coloring power when applied to the skin, resulting in heavy makeup and a natural finish. Moreover, since it has a strong adhesion to the skin, there is a problem in that it does not give a pleasant feel when used in cosmetics. Therefore, compared to the commonly used titanium dioxide for pigments, it has lower hiding power and coloring power.
Fine particle titanium dioxide with an average particle size of 10 to 50 nm, which has an excellent ultraviolet shielding effect due to its large specific surface area, has recently come to be used in place of organic ultraviolet absorbers, but the particle size is too small. Therefore, it is somewhat difficult to disperse, and like regular titanium dioxide, the shape of the particles is not uniform, and the adhesion to the skin is too strong, so when applied to the skin, it does not feel smooth or spread sufficiently. Yes, it was tough. Therefore, in order to improve the squeal and feel, flat minerals such as mica and sericite, nylon, etc.
Methods that use a combination of resin spheres such as polystyrene and epoxy, and inorganic spheres such as titanium dioxide, silica, and alumina have been adopted, but the particle sizes of these are extremely different from those of fine titanium dioxide, and There was a problem in that uniform mixing was extremely difficult due to differences in particle shape, specific gravity, etc. Summary of the present invention The present invention provides a coating on the surface of mica having an average particle size of 0.5 to 100 μm, with a coating amount of 20% by weight or less relative to the mica, and which does not substantially exhibit pearlescent, glitter, or hiding power due to interference. This invention relates to a UV-shielding pigment coated with fine titanium dioxide particles in its thickness. Detailed Description Titanium mica, which is made by coating mica with titanium dioxide and has a pearlescent luster, is often used in make-up cosmetics. The thickness of the titanium dioxide coating layer is adjusted so that silver color and other interference colors appear depending on the surface area. Therefore, when they are used in sunscreen foundations that require transparency, they produce a glittery appearance, which is rather inconvenient. Therefore, the ultraviolet-shielding pigment of the present invention is characterized in that the coating amount of fine particle titanium dioxide is set to a coating amount that does not substantially produce a pearlescent feeling or a glittering feeling due to interference colors. In other words, when the coating amount of fine-particle titanium dioxide is increased, a feeling of pearlescence and glitter will appear, and hiding power will also be developed. Therefore, fine-particle titanium dioxide is recommended for cosmetics that require skin-hiding power. The larger the amount of coverage, the more suitable it is, but for cosmetics that require transparency, such as sunscreen foundations, fine particle dioxide, which has no hiding power and virtually no pearlescent or glittery feel, is suitable. It is preferable that the amount of titanium coated is small. The coating amount of fine-particle titanium dioxide, which does not substantially produce pearlescent, glittering, or hiding power due to interference, varies depending on the type and particle size of the base mica, but generally it is 20% by weight based on the mica. % or less. In order to exhibit an ultraviolet shielding effect, it is suitable that the coating amount of fine particle titanium dioxide is 5% by weight or more based on the mica. In the case of UV-shielding pigments that are made by coating the mica surface with a thin layer of titanium dioxide, they themselves have a slight shine characteristic of mica, but when mixed into liquid paraffin, etc., mica has a refractive index of approximately 1.5, and as a medium it is difficult to use. It is transparent because its refractive index is close to that of the liquid paraffin used, and the particle size of the fine titanium dioxide coating the mica surface is sufficiently small compared to the wavelength of visible light, so it transmits visible light and is transparent. The result is something with a sense of feeling. Therefore, the UV-shielding pigment of the present invention forms a layer of titanium dioxide, which has a high refractive index compared to conventional mica titanium, and has a pearlescent appearance that utilizes light reflection and interference at the interface. Their functions are completely different. The UV-shielding pigment of the present invention does not give a glittering feeling, so even if it is incorporated in large amounts as a main ingredient in sunscreen foundations, it will not give a glittering feeling, and since it has a flat shape based on mica as a base material, it will not spread or feel. Since it has an excellent ultraviolet shielding effect on its own, there is no need to add fine particle titanium dioxide, which is normally used as an ultraviolet shielding agent, and even if it is added, only a small amount is needed, and it does not impair spread or feel. One of the drawbacks of fine particle titanium dioxide is that it is somewhat difficult to disperse because it is a fine particle, but the ultraviolet shielding pigment of the present invention has a large particle size based on the mica base material, so it is easy to disperse. In addition, since the fine particles of titanium dioxide are precipitated in a dispersed state on the mica base material without agglomeration, an improvement in the ultraviolet shielding effect due to the dispersion efficiency can be expected. In addition, UV-shielding pigments, which are hydrophobic substances, have a flat shape, so when they are made into cosmetics and applied to the skin,
Since the plate-like substance spreads to cover the skin surface, the effect of protecting the skin from ultraviolet rays is further improved compared to the case of using fine titanium dioxide powder. Furthermore, the UV-shielding pigment of the present invention whose surface has been hydrophobized has an improved feel on the skin, and is used in make-up cosmetics such as sunscreen foundations such as liquid paraffin, lanolin, stearic acid, and fatty alcohols. In addition, since the base material is mica, it has good fluidity and is less likely to aggregate during hydrophobization treatment, so it is easier to hydrophobe than when microparticle titanium dioxide is hydrophobized. Very easy to process. The ultraviolet-shielding pigment of the present invention can be obtained, for example, by adding an aqueous suspension of mica to an aqueous titanyl sulfate solution and subjecting it to thermal hydrolysis. In addition, for example, a method using conventionally known titanium sulfate (U.S. Pat. No. 3,087,828) or a method of forming a multilayer coating of titanium dioxide by thermally hydrolyzing titanium sulfate in several steps (Japanese Patent Laid-Open No. 11560/1983) Publication No. 2), etc. can be used.
Of course, it is also possible to employ a method in which titanium tetrachloride is used as a starting material and the surface of mica is coated with particulate titanium dioxide by hydrolysis. Muscovite is suitable as a base mica because it has low impurity content, transparency, and excellent surface smoothness, but other natural micas such as biotite and sericite, fluorine tetrasilicon mica, and Artificial micas such as taeniolite can also be used. In the present invention, the mica base material has an average particle size of 0.5 to
Mica of 100 μm is used, but this is because if the average particle size of mica is smaller than 0.5 μm, the dispersibility when compounded into cosmetics will be poor, and if the average particle size of mica is 100 μm.
This is because if the size is larger, a rough feeling will occur when a cosmetic is mixed and applied to the skin, resulting in a poor texture. An example of the production of the ultraviolet shielding pigment of the present invention is as follows. First, an aqueous titanium sulfate solution is added to an aqueous suspension of mica while stirring. In this case, mica may be added to the dilute aqueous titanyl sulfate solution. In addition, after heating while stirring and reaching the boiling point,
Maintain this state for at least 30 minutes. Alternatively, an aqueous suspension of mica may be heated to 80°C or higher while stirring, an aqueous titanyl sulfate solution may be added, and then heated until the boiling point is reached, and the state after reaching the boiling point may be maintained for 30 minutes or more. . After thermally hydrolyzing titanyl sulfate at boiling point for 30 minutes or more, it is filtered, washed with water, and dried according to a known method. Roast if necessary. Further, before washing and filtration with water, neutralization may be performed using a suitable alkali such as sodium hydroxide in order to prevent sulfate ions from remaining. More specifically, in the water-mica-titanyl sulfate system, the preferred concentrations of each of these present are as follows. The appropriate concentration of titanyl sulfate is 5 to 25 g/(in terms of TiO ₂ ). Further, the total sulfuric acid/total TiO ₂ (weight ratio) in titanyl sulfate is 1.5 to 6.0.
The concentration of mica is preferably 10 to 300 g/. Filtration is performed according to a known method, followed by drying. The obtained dried product may be used as it is, or if necessary, it may be roasted at 500 to 900°C for 30 minutes to 5 hours. Since the surface of UV-shielding pigments is hydrophilic,
By hydrophobicizing the surface, it becomes compatible with liquid paraffin, lanolin, stearic acid, fatty alcohols, etc. used in make-up cosmetics such as sunscreen foundations, and exhibits excellent dispersibility during mixing. Even rough products are stretched out, and the stickiness and texture are improved. The hydrophobic substances used for this purpose are not particularly limited and are known ones, such as waxes, higher fatty acids, polyvalent metal salts of higher fatty acids, higher fatty acid triglycerides, higher aliphatic alcohols, and higher aliphatic alcohol sulfates. These include polyvalent metal salts and their derivatives. Further, as the hydrophobic substance, organic fluorine compounds such as perfluorinated higher fatty acids and higher fatty alcohols, partially fluorinated higher fatty acids and higher fatty alcohols, and organosilicon compounds such as polysiloxanes and silanes can also be used. Particularly preferred are organosilicon compounds. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 (Production of 5% TiO ₂ coated mica) Titanyl sulfate aqueous solution (total sulfuric acid/total TiO ₂ = 1.7,
TiO ₂ equivalent concentration = 15g/) Average particle size in 1
285 g of 7 μm muscovite was added, heated with stirring, and maintained at this state for an additional 2 hours after boiling. After filtering the product and washing with water, separate the cake and heat at 110℃.
After drying in
_TiO2 coated mica) was produced. Example 2 (Production of 10% TiO ₂ coated mica) In the same manner as in Example 1 except that 135 g of muscovite was added, the surface of muscovite was coated with fine titanium dioxide at 10% by weight based on the muscovite. A UV-shielding pigment (10% TiO ₂ coated mica) was produced. Example 3 (Production of 20% TiO ₂ coated mica) In the same manner as in Example 1 except that 60 g of muscovite was added, the surface of the muscovite was coated with fine particle titanium dioxide at 20% by weight relative to the muscovite. A UV-shielding pigment (20% TiO ₂ coated mica) was produced. Example 4 (Hydrophobization treatment) Methylhydrodiene polysiloxane (manufactured by Shin-Etsu Silicone Co., Ltd., trade name silicone oil KF-99)
1 g was diluted 20 times with acetone. This diluted solution was added by spray to 100 g of the ultraviolet shielding pigment obtained in Example 1, which was being mixed in a V-type mixer. After the addition was complete, mixing continued for approximately 2 hours. this
The mixture was heated at 150°C for 2 hours to obtain a polysiloxane-treated ultraviolet shielding pigment with excellent fluidity. Example 5 (Measurement of ultraviolet shielding effect-1) In order to investigate the optical properties of the ultraviolet shielding pigments obtained in Examples 1 to 3, a nitrocellulose paint was prepared with the following formulation. (Painting conditions) Nitrocellulose 32.0g (Solid content 20.8% by weight) Sample 2.0g Alumina beads 50g Pigment solid content weight/Resin solid content weight = 0.3 Pour the above mixture into a mayonnaise bottle and disperse with paint conditioner for 20 minutes. did. For comparison, a sample was prepared in which the same amounts of mica as a base material, fine particle titanium dioxide (manufactured by Teikoku Kako Co., Ltd., trade name MT-500B), and anatase type titanium dioxide for pigments (manufactured by Teikoku Kako Co., Ltd.) were blended. (Coating conditions) The coating was applied to the hiding power test paper using a 3 mil applicator and to the cellophane paper using a 1.5 mil applicator. The Y value was measured using a color difference system from the coating film of the hiding power test paper produced by the above method, and is shown in Table 1. Furthermore, the light transmittance of the cellophane paper coating was measured using a spectrophotometer equipped with an integrating sphere, and the results are shown in FIG. In Table 1, the UV shielding pigment of Example 1 is "5% TiO ₂ coated mica", the UV shielding pigment of Example 2 is "10% TiO ₂ coated mica", and the UV shielding pigment of Example 3 is "20% TiO 2 coated mica". % _TiO2 coated mica”. Furthermore, in FIG. 1, the amount of coating of fine particle titanium dioxide is expressed as "TiO ₂ coating amount."

【table】

[Table] Y/Y (%) in Table 1 is (Y value on blackboard/
Y value on the white board) x 100, which is an indicator of hiding power. As is clear from Table 1, the Y/Y (%) value increases with the increase in the coating amount of fine particle titanium dioxide (that is, the TiO ₂ coating amount), and the coating amount is 20% by weight.
is almost equal to the Y/Y (%) value of fine-particle titanium dioxide, but fine-particle titanium dioxide has a small particle size and transmits visible light, so it has no hiding power.
It can be seen that the ultraviolet shielding pigments obtained in Examples 1 to 3 do not substantially exhibit hiding power. In addition, as is clear from Figure 1, as the amount of coating of fine titanium dioxide increases, the ultraviolet region (wavelength
It can be seen that the transmittance in the region below 390 nm is small, indicating that the UV-shielding pigments obtained in Examples 1 to 3 of the present invention have excellent UV-shielding effects. Example 6 (Measurement of ultraviolet shielding effect-2) Amount of titanium dioxide in the ultraviolet shielding pigment obtained in Example 1, fine particle titanium dioxide (MT-500B), and anatase type titanium dioxide for pigments (manufactured by Teikoku Kako Co., Ltd.) The following formulations were prepared using the same ingredients, and the light transmittance was measured in the same manner as in Example 5. The results are shown in FIG.

[Table] Ray-shielding pigments

[Table] In Figure 2, varnish 1 indicates the transmittance of only nitrocellulose, 2 anatase indicates the transmittance of a formulation containing anatase-type titanium dioxide for pigments, and 3 MT-500B. indicates the transmittance of a formulation containing fine particle titanium dioxide (MT-500B), and 5% coated mica in 4 refers to the ultraviolet shielding pigment of Example 1 (muscovite surface coated with 5% by weight of fine particle titanium dioxide). The figure shows the transmittance of a formulation containing UV-shielding pigments. As is clear from FIG. 2, when the amount of titanium dioxide is the same, the ultraviolet shielding pigment of Example 1 of the present invention is clearly superior to atanase-type titanium dioxide for pigments and fine particle titanium dioxide (MT-500B). It has an excellent UV shielding effect. Next, Examples 7 and 8 show cases in which foundations were prepared by blending the ultraviolet-shielding pigment of the present invention. Note that the blending ratio is in parts by weight. Example 7 (Powder foundation) Ingredients [A] Talc 20 Ultraviolet shielding pigment of Example 2 60 Zinc stearate 5.0 Coloring pigment 5.0 Ingredient [B] Liquid paraffin 6.0 Lanolin 5.0 Sorbitan monooleate 2.0 Fragrance Appropriate amount Powder foundation To prepare the solution, component [A] is stirred and mixed in a Henschel mixer, then component [B] is heated and dissolved, this is added to component [A], stirred and mixed, pulverized in a grinder, and crushed in a metal plate. This was achieved by press molding and commercializing the product. The powder foundation prepared as described above has general characteristics as a foundation, has an excellent UV-shielding effect based on the UV-shielding pigment of Example 2, and also has an excellent UV-shielding effect when applied to the skin. The feel and elongation were both good. Example 8 (Oil-based foundation) Component [A] Carnauba wax 2.0 Ceresin 2.0 Microcrystalline wax 2.0 Liquid paraffin 25.0 Silicone oil 15.0 Lanolin 5.0 Component [B] Ultraviolet shielding pigment of Example 3 20 Talc 10 Coloring pigment 5 Pigment dioxide Titanium 10 To prepare an oil-based foundation, add ingredient [A].
The mixture was heated and dissolved at 85° C. or higher, and while stirring, the premixed component [B] was added little by little to the mixture and well dispersed. Thereafter, the mixture was allowed to cool to 70°C, an appropriate amount of fragrance was added, the mixture was filled into a metal plate, and the mixture was allowed to cool to room temperature to produce a product. The oil-based foundation prepared as described above has general characteristics as a foundation, has an excellent UV-shielding effect based on the UV-shielding pigment of Example 3, and also has an excellent UV-shielding effect when applied to the skin. The feel and elongation were both good.

[Brief explanation of the drawing]

Figure 1 is a graph showing the light transmittance versus wavelength of the ultraviolet shielding pigments obtained in Examples 1 to 3, and Figure 2 is a graph showing the ultraviolet shielding pigments obtained in Example 1 and commercially available anatase type dioxide for pigments. 1 is a graph showing the optical transmittance of titanium and particulate titanium dioxide with respect to wavelength.

Claims (1)

[Scope of Claims] 1. On the surface of mica having an average particle size of 0.5 to 100 μm, at a coating amount of 5 to 20% by weight based on the mica, and at a coating thickness that does not substantially produce pearl luster, glitter, and hiding power. A UV-shielding pigment coated with fine particles of titanium dioxide. 2. The ultraviolet shielding pigment according to claim 1, the surface of which is treated with a hydrophobic substance. 3. The ultraviolet shielding pigment according to claim 2, wherein the hydrophobic substance is an organosilicon compound.