Ultraviolet ray screening agent

Abstract: The object of the present invention is to provide composite synthetic mica powder having excellent ultraviolet ray screening effect. The composite synthetic mica powder of the present invention is characterized in that a mica fine particle layer (B) containing one or more types of elements selected from a group of Te, Bi, Pb, Ce, Fe, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn and Ti is formed on the surface of scale-like mica particles (A), whereby: covering ratio of said particles (A) by said particles (B) is lower than or equal to 1 and higher than or equal to 0.5; and ratio of particle size of said particles (B) to plane direction diameter of said particles (A) is lower than or equal to 0.1, and particle size of said particles (A) is 1 to 100 µm. Another object of the present invention is to provide red synthetic mica, which develops light-resistant red color closer to color of human skin and ultraviolet ray, and also to provide a method for manufacturing the same and an ultraviolet ray screening agent containing said synthetic mica. The synthetic mica of the present invention is characterized in that, it is expressed by the following formula (I): X 1/3∼1 Y 2∼3 (Z₄ O₁₀) F 2×0.75∼2×0.99 (I) (where X represents one or more types of ions selected from a group of Na, K, Li, Ca, Rb and Sr, Y represents one or more types of ions selected from a group of Mg, Fe, Ni, Mn, Al, Li, Co, Ti and Zn, Z represents one or more types of ions selected from a group of Al, Si, Ge, Fe, B, Co and Ti, and at least one of Y and Z represents an iron ion), molar number of iron contained in said synthetic mica is 0.01 to 3 mols, and, when said synthetic mica is measured by powder cell method, its color is given by L*=55 to 75, a*=5 to 20, and b*=5 to 20 by the CIE 1976 (L*a*b*) space.

Description: BACKGROUND OF THE INVENTION The present invention relates to composite mica powder to be used as base material for paint, ink, coating agent, plastic, film, fiber, glass, and glaze, and also to an ultraviolet ray screening agent containing said mica powder. Mica powder is used as a filling material for plastics and paint or as pigment for cosmetic products. Also, a mica product having interference color and with its surface covered with an oxide having high refractive index such as titanium oxide is known as "pearl mica". On the other hand, as means for screening ultraviolet ray, methods are known such as a method for screening ultraviolet ray by scattering effect of particles and a method to absorb ultraviolet ray energy and to convert it to thermal energy. A typical example of the former is to use titanium oxide, and this is used as an ultraviolet ray scattering agent in cosmetic products, plastics, etc. As the material for the latter, an ultraviolet ray absorbing agent having benzophenone and the like as principal component is known. In addition, a large number of ultraviolet ray screening agent have been proposed. For example, there are composite oxide of metal such as aluminum and zinc (Japanese Patent Laid-Open Publication No. 62-275182), zirconia particle containing cerium (Japanese Patent Laid-Open Publication No. 2-135275), etc. Also, an ultraviolet ray absorbing agent containing mica has also been proposed. For example, there are a product having nickel-containing synthetic mica as main component (Japanese Patent Laid-Open Publication No. 58-19379), a product having synthetic mica containing Te and the like as main component (Japanese Patent Laid-Open Publication No. 3-33179), etc. Also, an ultraviolet ray screening pigment has been proposed (Japanese Patent Laid-Open Publication No. 62-187770), which is covered with titanium oxide in such quantity that pearl luster due to interference does not virtually appear on mica surface. On the other hand, mica has been widely used for cosmetic products because it has excellent transparent property, luster and high extensibility. In recent years, not only natural mica but also synthetic mica have been developed as an additive for cosmetic products (Japanese Patent Laid-Open Publication No. 63-241072). The mica powder of conventional type has been used as scale-like particles of about 1 to 500 µm after pulverized by dry or wet type pulverizing method. This conventional type mica powder is disadvantageous in that it can utilize only the heat-resistant and insulating properties of the mica powder. For this reason, ultraviolet ray absorbing function is provided by giving interference color through adoption of particle structure covered with titanium oxide as in the case of the pearl mica described above or by a method to replace the elements in mica with other elements through synthesis. However, the pearl mica covered with titanium oxide can give interference color, but it has no transparency specific to mica, or titanium oxide has poor resistance to light. The ultraviolet ray absorbing mica which contains specific elements does not have sufficient effect to screen ultraviolet ray. In the ultraviolet ray screening agent, the ultraviolet ray scattering agent such as titanium oxide has excellent effect to screen ultraviolet ray while it impairs transparency of mica because it also scatters visible ray, and this is not suitable for the application where transparency is required. In case it is blended in cosmetic products, white color is exaggerated and gives unnatural impression. On the other hand, organic type ultraviolet ray absorbing agent has outstanding ultraviolet ray absorbing potency within a specific wavelength range, but it has poor weatherproof property and lacks stability. As natural mica, muscovite, phlogopite, and biotite are known, and these are grayish white to blackish brown in color. Mica can be synthesized by various methods, and it is known that mica in outstanding white color can be obtained from synthesis and that colored synthetic mica can be produced by coordinating colored elements in crystal structure. On the other hand, mica is widely used in cosmetic products because it has high transparent property, luster and extensibility in use. In recent years, not only natural mica but also synthetic mica has been developed as an additive for cosmetic products. For example, the Japanese Patent Laid-Open Publication No. 63-241072 discloses a synthetic mica powder, in which less fluorine ions are eluted and which has low surface activity and high oil impregnation property. As described above, mica has not been used widely because color cannot be given to it, and despite of its excellent property, only the properties such as insulating property or leafing property coming from its scale-like shape can be utilized. In the fields of paint, plastics, cosmetic products, etc., there are strong demands on a material, which is red in color and has ultraviolet ray screening effect to improve durability of organic substances. To give red color, however, it is necessary to add a coloring agent such as organic dye or iron oxide. Because organic dye has low resistance to light and iron oxide contains particles with high refractive index, it is likely to cause unevenness and impairs transparency important to cosmetic products. On the other hand, ultraviolet ray scattering agent such as titanium oxide or organic type ultraviolet ray absorbing agent are used in cosmetic products to defend against ultraviolet ray. Although ultraviolet ray scattering agent has excellent effect to screen ultraviolet ray, it also scatters visible ray. This leads to impairment of transparency and causes choking and, whitening of cosmetic products. Organic type ultraviolet ray absorbing agent has outstanding ultraviolet ray absorbing potency within a specific wavelength range but has poor weatherproof property. SUMMARY OF THE INVENTION It is an object of the present invention to provide composite mica powder, which has excellent ultraviolet ray screening effect due to scattering action of mica particles. It is another object of the present invention to proyide composite mica powder, which has high ultraviolet ray screening potency but also bright external appearance when blended in cosmetic products and is also superb in usability and workability. To attain the above objects, the present inventors have studied with strenuous efforts and found that, by forming synthetic mica particles having ultraviolet ray absorbing potency on mica surface, excellent ultraviolet ray screening effect is obtained because ultraviolet ray is scattered when said synthetic mica particles absorb ultraviolet ray. Specifically, the present invention provides composite mica powder and an ultraviolet ray screening agent containing said mica powder, said mica powder comprising a synthetic mica particle layer (B) containing one or more types of elements selected from a group of Te, Bi, Pb, Ce, Fe, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn and Ti on surface of mica particle (A), whereby: the covering ratio of the above particle (A) by the above (B) is equal to or lower than 1 and is equal to or higher than 0.5; the ratio of particle size of the above (B) to particle size of the above (A) is higher than 0 and is equal to or lower than 0.1; and particle size of the above (A) is 1 to 100 µm. The above covering ratio can be calculated by the sum of a projected area of the particle (B) divided by a projected area of the particle (A). Each of the projected areas can be determined under scanned electron microscope. The particle size of the above (A) or (B) is: short axis + long axis 2 of the particle observed under scanning electron microscope. The above and other objects and advantageous features of the invention will become more apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an electron micrograph showing particle structure of composite mica powder according to the present invention as obtained by the Example 1; Fig. 2 is an electron micrograph showing particle structure of composite mica powder of the present invention as obtained by the Example 5; Fig. 3 is an electron micrograph showing particle structure of composite mica powder of the present invention as obtained by the Example 17; Fig. 4 is an electron micrograph showing particle structure of composite mica powder of the present invention as obtained by the Example 18; Fig. 5 is an X-ray diffraction chart of composite mica powder of the present invention as obtained by the Example 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The mica particle (A) used in the present invention is one or more types of mica, which are selected from a group of natural muscovite, phlogopite, biotite, sericite and synthetic mica. Among these, it is preferable to use mica, which contains one or more elements selected from a group of Te, Bi, Pb, Ce, Fe, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn and Ti. Particle diameter of the mica particle (A) is 1 to 100 µm. Synthetic mica fine particle (B) used in the present invention must be mica, which contains one or more types of elements selected from a group of Te, Bi, Pb, Ce, Fe, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn and Ti. The mica fine particles not containing these elements cannot provide high effect for screening ultraviolet ray. The shape of the synthetic mica fine particles (B) is not specified, but it is preferable that particle size is 1 µm or less, preferably, 0.5 µm or less, or more preferably 0.1 µm or less. The composite mica powder of the present invention must contain synthetic mica fine particle layer (B) which is formed in such manner that the covering ratio of the above particle (A) by the above particle (B) is lower than or equal to 1 and higher than or equal to 0.5, that the ratio of particle size of the above (B) to particle size of the above (A) is higher than 0 and lower than or equal to 0.1, and that the particle size of the above (A) is 1 to 100 µm. If not within this range, the covering of the synthetic mica fine particle layer (B) is not sufficient, and satisfactory ultraviolet ray effect is not obtained. In case the particle size (B) is larger than the particle size of (A), the particles (B) may not be attached in radial direction. To form the synthetic mica fine particle layer (B), the mica fine particles to be formed may be attached in particle state or may be firmly fixed by sintering or by fusion. Next, description will be given on a method to produce composite mica powder. To obtain the composite mica powder of the present invention, synthetic mica fine particles (B) pulverized to 1 µm or less by a wet type or dry type pulverizer and natural or synthetic mica particles (A) with particle size of 5 to 100 µm are selected so that the ratio of particle size of the above (B) to particle size of the above (A) is higher than 0 and is lower than or equal to 0.1, and this is mixed homogeneously by a V type mixer. Then, synthetic mica fine particle layer (B) is formed on the surface of mica particles (A) by a mechano-chemical reactor such as Ang mill (manufactured by Hosokawa Micron) or medium type pulverizer such as ball mill so that the covering ratio of the above (A) by the above (B) is lower than or equal to 1 and higher than or equal to 0.5. In this case, the better results can be obtained if synthetic mica fine particles (B) not formed on the surface of the mica particles (A) are removed by classifying. The composite mica powder thus prepared can be foliated by treating with acid or chelating agent. Thus, mica powder with low surface activity and good oil impregnation property suitable for cosmetic products can be obtained. For the treating, inorganic and organic acids may be used. As the inorganic acids, there are, for example, hydrochloric acid, nitric acid, sulfuric acid, chloric acid, perchloric acid, periodic acid, bromic acid, phosphoric acid, boric acid and carbonic acid. As the organic acids, there are carboxylic acids such formic acid, acetic acid, acrylic acid, benzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid and phthalic acid, oxycarboxylic acids such as lactic acid, malic acid, tartaric acid and citric acid, and amino acids such as glycine, alanine, valine, leucine, thyrosine, threonine, serine, proline, tryptophan, methionine, cystine, thyroxine, asparagine, glutamic acid, lysine, and arginine. As chelating agents, there are ethylenediaminetetraacetic acid, nitrilotriacetic acid, 1,2-diaminocyclohexanetetra-acetic acid, N-oxyethylethylenediamine-triacetic acid, ethleneglycol-bis-tetraacetic acid, ethylenediamine-tetrapropionic acid, etc. The synthetic mica fine particles (B) formed on the surface may be sintered or fused through heat treatment at 700 to 1200°C. By heat treatment, mica particles (A) can be turned to particles in form of hexagonal plate. The processing by the above acids or chelating agents and heat treatment may be simultaneously performed. In an alternative method for manufacturing composite mica powder of the present invention, mica powder containing one or more types of elements selected from a group of Te, Bi, Pb, Ce, Fe, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn and Ti is processed by a rotary pulverizer, pulverizing by friction of mica particles themselves and adding solvent such as water by about 10 to 40%. By this procedure, composite mica powder can be obtained by forming fine particle mica containing one or more types of elements selected from the group of Te, Bi, Pb, Ce, Fe, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn and Ti on the surface of mica particles. The composite mica powder thus prepared can be treated by the acids or the chelating agents as described above, or by heat treatment at 700 to 1200°C or by combining both methods. The composite mica powder of the present invention can be used alone or can be blended and mixed with cosmetic pigment, coloring pigment, ultraviolet ray scattering agent and ultraviolet ray absorbing agent. As cosmetic pigment usable in the present invention, there are talc, kaolin, mica, calcium carbonate, magnesium carbonate, magnesium silicate, silicic anhydride, barium sulfate, nylon powder, polyethylene powder, polystyrene powder, etc. As coloring pigment, there are iron oxide, ultramarine blue, chromium oxide, Prussian blue, carbon black, etc. As ultraviolet ray scattering agents, there are titanium -oxide, titanium oxide ultra-fine particle, zinc oxide, etc. As ultraviolet ray absorbing agents, there are benzophenone type and benzotriazole type ultraviolet ray absorbing agents. It is preferable to blend the composite mica powder by about 1 to 100%, and the blending ratio should be selected according to the intended purpose, property, etc. of the products. It is known that synthetic mica containing Te and the like has effect to absorb ultraviolet ray (Japanese Patent Laid-Open Publication 3-33179). The present invention is based on the findings that, by forming fine particles of synthetic mica having such ultraviolet ray absorbing potency, ultraviolet ray screening effect can be obtained due to unexpected ultraviolet ray scattering effect of the mica fine particles. When synthetic mica is simply turned to fine particles, problems occur such as coarsening of particles by the secondary aggregation or difficulty of homogeneous dispersion to material, and it is not possible to obtain high ultraviolet ray screening effect as in the composite mica powder of the present invention. If the particle size ratio is higher than the specified value, covering is insufficient, and high ultraviolet ray screening effect as in the present invention cannot be obtained. Through study of particle structure of mica powder, the present inventor has found that, by forming mica fine particles with specific particle size ratio on the surface of mica particles, composite mica powder can be obtained, which can solve the above problems and which can provide excellent ultraviolet ray screening effect. Next, detailed description will be given on the features of the present invention in connection of the examples, while the present invention will not be limited to these examples. (Example 1) A mixture was prepared, which contains potassium silicofluoride by 18.2 w/w %, potassium carbonate by 7 w/w %, magnesium oxide by 28.2 w/w %, aluminum oxide by 11.9 w/w %, and silicon dioxide by 37.0 w/w %. To 100 weight parts of this mixture, 19.0 weight parts of tellurium dioxide were added, and these were mixed for 30 minutes by V type mixer. Next, this mixture was placed in an alumina crucible. After melting this in electric furnace at 1450°C for 30 minutes, it was cooled down in the furnace. Synthetic tellurium-containing mica thus obtained was pulverized in a ball mill for 48 hours, and 100 parts of mica fine particles containing tellurium of 0.5 µm or less were obtained through centrifugation and classifying. To 100 g of the mica fine particles containing tellurium dioxide thus obtained, 100 g of natural mucovite (about 10 µm) was added, and the mixture was processed in a ball mill by mechano-chemical processing for 24 hours, and 195 g of the composite mica powder of the present invention was obtained. This composite mica powder was examined under scanning electron microscope (T-330A; JEOL, Ltd.). Electron micrograph is shown in Fig. 1. The composite mica powder is added to castor oil at 20% concentration. After mixing this in a 3-roll mill, it was coated on a transparent quartz plate in thickness of 10 µm, and UV transmittance at 300 nm was measured using UV spectrophotometer (U-3210; Shimadzu). As the result, UV transmittance at 300 nm was 15%. Therefore, UV screening ratio was 85%. (Examples 2 to 4) To 100 weight parts of a mixture shown in Table 1, a compound given in Table 2 was mixed at a ratio described in Table 2, and the composite mica powder of the present invention was prepared by the same procedure as in the Example 1. On the composite mica powder thus prepared, UV screening ratio was measured by the same method as in the Example 1. The results are given in Table 3. (Example 5) A mixture was prepared, which contains potassium silicofluoride by 19.3 w/w %, potassium carbonate by 5 w/w %, magnesium oxide by 30.0 w/w %, aluminum oxide by 6.3 w/w %, and silicon dioxide by 39.4 w/w %. To 100 weight parts of this mixture, 10 weight parts of iron oxide were added, and this was mixed for 30 minutes by V type mixer. The mixture thus obtained was placed in an alumina crucible and melted in electric furnace at 1450°C for 30 minutes and cooled down in the furnace. Thus, 100 parts of synthetic iron-containing mica were obtained. After 200 g of this synthetic mica was pulverized in a ball mill for 48 hours, 100 g of mica fine particles containing iron with particle size of 0.5 µm or less was obtained through centrifugation and classifying. To 100 g of micro fine particles containing iron thus prepared, 100 g of the above iron-containing synthetic mica (diameter in plane direction: 10 µm) was added, and the mixture was processed for 24 hours in a ball mill through mechano-chemical processing, and 180 g of the composite mica powder of the present invention was obtained. Electron micrograph of this composite mica powder is given in Fig. 2. Fig. 5 shows an X-ray diffraction chart measured by RAD-B (Rigaku Denki-Sha). It complied with ASTM provisions for iron-containing mica according to this X-ray diffraction chart. Further, on the composite mica powder thus prepared, UV screening ratio was determined by the same procedure as in the Example 1. The results are given in Table 3. (Examples 6 to 10) To 100 weight parts of the mixture of Table 1, a compound of Table 2 was mixed at a ratio given in Table 2, and the composite mica powder of the present invention was prepared by the same procedure as in the Example 5. On the composite mica powder thus obtained, UV screening ratio was determined by the same procedure as in the Example 1. The results are given in Table 3. (Example 11) A mixture was prepared, which contains potassium silicofluoride by 18.2 w/w %, potassium carbonate by 7 w/w %, magnesium oxide by 28.2 w/w %, aluminum oxide by 11.9 w/w % and silicon dioxide by 37.0 w/w %. To 100 weight parts of this mixture, 11 weight parts of vanadium oxide were added, and the mixture was mixed for 30 minutes by V type mixer. Next, this mixture was placed in an alumina crucible. After melting for 30 minutes at 1450°C in electric furnace, it was cooled down in the furnace. The crystallized mass thus obtained was crushed by an impact crusher to the size of about 150 µm (=100 mesh) 4 kg of vanadium-containing synthetic mica thus obtained and 2 kg of water were placed in an agitator type pulverizer, and after pulverizing it for 96 hours, it was classified, and 1.8 kg of the composite mica powder of the present invention with fine particle mica powder attached on the surface was obtained. On the composite mica powder thus obtained, UV screening ratio was determined by the same procedure as in the Example 1. The results are given in Table 3. (Examples 12 to 16) To 100 weight parts of the mixture described in Table 1, a compound given in Table 2 was mixed by a ratio of Table 2, and the composite mica powder of the present invention was produced by the same procedure as in the Example 11. On the composite mica powder thus prepared, UV screening ratio was determined as in the Example 1. The results are given in Table 3. (Example 17) A mixture was prepared, which contains potassium silicofluoride by 19.3 w/w %, potassium carbonate by 5 w/w %, magnesium oxide by 30.0 w/w %, aluminum oxide by 6.3 w/w %, and silicon dioxide by 39.4 w/w %. To 100 weight parts of this mixture, 10.0 weight parts of iron oxide and 10.0 weight parts of titanium oxide were added, and these were mixed for 30 minutes by V type mixer. Then, the mixture was placed in an alumina crucible, melted in electric furnace for 30 minutes at 1450°C and cooled down in the furnace. The crystal mass thus obtained was crushed to the size of 150 µm (=100 mesh) by an impact crusher. 4 kg of synthetic mica powder containing iron and titanium thus prepared and 2 kg of water were placed in an agitator type pulverizer and pulverized for 120 hours. After classifying, 2 kg of the composite mica powder of the present invention with fine particle mica powder attached on the surface was obtained. Electron micrograph of this composite mica powder is shown in Fig. 3. On the composite mica powder thus obtained, UV screening ratio was determined as in the Example 1. The results are shown in Table 3. (Example 18) 70 g of the composite mica powder of the present invention prepared in the Example 17 was placed in an alumina crucible. Through heat treatment at 1000°C for 24 hours in electric furnace, a heat-treated product of the composite mica powder of the present invention was obtained. When mica fine particles formed on the mica powder surface were examined under electron microscope, the mica powder was sintered or fused. Also, the composite mica powder was in form of hexagonal plate. Fig. 4 shows an electron micrograph of the composite mica powder. On the composite mica powder thus prepared, UV screening ratio was determined as in the Example 1. The results are given in Table 3. (Examples 19 to 20) To 100 weight parts of the mixture described in Table 1, a compound of Table 2 was mixed at a ratio shown in Table 2, and the composite mica powder of the present invention was produced by the same procedure as in the Example 17. On the composite mica powder thus prepared, UV screening ratio was determined as in the Example 1. The results are given in Table 3. (Comparative example 1) Mica powder was prepared by the same procedure as in the Example 1 except that tellurium-containing mica fine particles were not used in the Example 1. On the mica powder thus obtained, UV screening ratio was determined as in the Example 1. The results are given in Table 3. (Comparative example 2) Mica powder was obtained by the same procedure as in the Example 5, except that iron-containing mica fine particles were not used in the Example 5. Fig. 5 shows an X-ray diffraction Chart of this mica powder. On the mica powder thus obtained, UV screening ratio was determined as in the Example 1. The results are given in Table 3. (Comparative example 3) Mica powder was obtained by the same procedure as in the Example 19, except that fluorine phlogopite was used instead of iron-containing mica in the Example 19. On this mica powder, UV screening ratio was determined as in the Example 1. The results are given in Table 3. (Comparative example 4) Mica powder was obtained by the same procedure as in the Example 1, except that particle size of tellurium-containing mica fine particles is 2 µm in the Example 1. On the mica powder thus obtained, UV screening ratio was determined as in the Example 1. The results are given in Table 3. (Comparative example 5) Mica powder was prepared by the same procedure as in the Example 11 except that 10 kg of zirconia balls of 5 mm were used in the agitator type pulverizer in the Example 11. On the mica powder thus prepared, UV screen ratio was determined as in the Example 1. The results are given in Table 3. Mixing ratio of major materials of the mixtures A to F (%). Major materials A B C D E F K₂SiF₆ 18.2 19.3 20.6 19.5 21.1 19.1 K₂CO₃ 4.7 5.0 5.3 5.1 5.5 5.0 MgO 28.2 30.0 32.0 30.3 32.8 29.6 Ai₂O₃ 11.9 6.9 12.8 13.8 SiO₂ 37.0 39.4 42.1 32.3 26.8 46.3 Total 100 100 100 100 100 100 Material blending table. Example No. Mixture (weight parts) Compound A B C D E F Type Weight parts 1 100 TeO₂ 19 2 100 Bi₂O₃ 28 3 100 PbO₂ 28 4 100 CeO₂ 10 5 100 Fe₂O₃ 10 6 100 MoO₃ 38 7 100 Nb₂O₃ 16 8 100 WO₃ 29 9 100 Sb₂O₃ 18 10 100 SnO₂ 18 11 100 V₂O₃ 11 12 100 KnO₂ 10 13 100 NiO 10 14 100 CoO 15 15 100 ZnO 22 16 100 TiO₂ 20 17 100 Fe₂O₃ 10 TiO₂ 10 19 CeO₂ 4 100 Fe₂O₃ 10 20 100 ZnO 22 TiO₂ 10 As described above, it is possible according to the present invention to obtain excellent ultraviolet ray screening effect by unexpected scattering effect of mica fine particles by forming mica fine particle layer having ultraviolet ray absorbing potency on the surface of mica powder. Thus, the composite mica of the present invention is very useful as base material for cosmetic product, paint, ink, coating agent, plastics, film, fiber, glass, glaze, etc. In particular, cosmetic product blended with the mica powder of the present invention has excellent ultraviolet ray screening effect, bright external color and superb in usability and workability. Because the synthetic mica of the present invention has excellent ultraviolet ray screening effect, it can be mixed and used in cosmetic product, plastics, paint, etc. as an ultraviolet ray screening agent.

Claims: Composite mica powder, comprising mica particles (A) with synthetic mica fine particle layer (B) formed on the surface thereof, said synthetic mica fine particle layer contains one or more types of elements selected from a group of Te, Bi, Pb, Ce, Fe, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn and Ti, whereby: covering ratio of said particles (A) by said particles (B) is lower than or equal to 1 and higher than or equal to 0.5; and ratio of particle size of said particles (B) to particle size of said particles (A) is higher than 0 and lower than or equal to 0.1, and particle size of said particle (A) is 1 to 100 µm. Composite mica powder according to Claim 1, wherein said composite mica powder is processed by heat treatment at 700 to 1200°C. An ultraviolet ray screening agent containing composite mica powder, which comprises mica particles (A) wit synthetic mica fine particle layer (B) formed on the surface thereof, said synthetic mica fine particle layer contains one or more types of elements selected from a group of Te, Bi, Pb, Ce, Fe, Mo, Nb, W, Sb, Sn, V, Mn, Ni, Co, Zn and Ti, whereby: covering ratio of said particles (A) by said particles (B) is lower than or equal to 1 and higher than or equal to 0.5; and ratio of particle size of said particles (B) to plane direction diameter of said particles (A) is smaller than or equal to 0.1, and particle size of said particles (A) is 1 to 100 µm.

Inventors: ANDO AKITSUGU, KOSUGI TETSUSI, OGAWA KATSUKI, OHNO KAZUHISA, SUZUKI FUKUJI, TAKAO YUJI, ANDO, AKITSUGU, KOSUGI, TETSUSI, OGAWA, KATSUKI, OHNO, KAZUHISA, SUZUKI, FUKUJI, TAKAO, YUJI, Ogawa, Katsuki, c/o Shiseido Research Center, Ohno, Kazuhisa, c/o Shiseido Research Center, SUZUKI, FUKUJI, C/O SHISEIDO RESEARCH CENTER
Applicants: SHISEIDO CO LTD, TOPY IND, SHISEIDO COMPANY LIMITED, TOPY INDUSTRIES LIMITED
Application year: 1992
Main classification: C09C1
IPC codes: C01G49, A61K8, C04B14, A61Q17, C01G1, C09K3, C01B33, C09C1, C09C3