Inorganic composite powder and cosmetic comprising the same

Details Inorganic composite powder and cosmetic comprising the same Inorganic composite powder and cosmetic comprising the same

2000-09-29

2002-11-19

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Cosmetic, antiperspirant, dentifrice

C424S490000, C424S064000, C424S062000, C424S061000, C424S063000, C424S400000

Reexamination Certificate

active

06482419

ABSTRACT:

This application is a 371 of PCT/JP99/0152 filed Mar. 25, 1999.
FIELD OF THE INVENTION
The present invention relates to an inorganic composite powder with a coating layer comprising two or more inorganic oxides having different refractive indexes respectively and formed on a scaled substrate such as mica and to a cosmetic comprising the inorganic composite powder.
BACKGROUND TECHNOLOGY
Conventionally a scaled powder such as mica, talc, and sericite has been used for preparing make-up cosmetics such as powder foundation. The effects provided by blending of this scaled powder includes the excellent extendability of the cosmetic on the human skin, improved dispersive property of coloring pigments used therein, and its excellent capability of adhering to the human skin, so that the scaled powder is indispensable in preparation of make-up cosmetics.
These scaled powders as described above generally have a low refractive index of 1.7 or below, and when wet with oily materials blended in a cosmetic, the transparency becomes higher with the capability of covering the human skin as the ground lowered, so that it is required to blend a somewhat large quantity of titanium oxide pigment or the like in the cosmetic to compensate the defects. When a cosmetic with a somewhat large quantity of titanium oxide blended therein is used for making up, the finishing looks like that provided in daubing, which does not satisfy recent preference of users for the natural feeling of appearance.
Japanese Patent Laid-Open Publication No. 282312/1990 discloses a spherical composite powder which easily collapses when pressurized and comprises titanium oxide and silica, and discloses a cosmetic comprising mica powder prepared by coating titanium oxide and then silica thereon.
Further the present inventors proposed in the International Laid-Open Publication WO 92/03119 a composite powder prepared by depositing spherical silica with the size in the order less than a micron on a surface of a scaled substrate to homogeneously scatter light and having the effect of shading the ground. However, as this composite powder comprises silica having the low refractive index and a scaled substrate, when the composite powder is wet by oil mixed in the cosmetic, the transparency becomes higher so that the effect of covering defects on the human skin becomes disadvantageously lower.
Different from this publication, scaled substrates such as barium sulfate have been proposed from a similar view point of homogeneously scattering light, but as their refractive index is high, the requirement for the natural feeling of appearance is not sufficiently satisfied.
Further cosmetics having a satisfactory covering capability for covering such defects as blots and freckles on the human skin and insuring the feeling of transparency are proposed in Japanese Patent Laid-Open Publication No. 56628/1994 and Japanese Patent Laid-Open Publication No. 188723/1996, but these cosmetics are prepared by coating a scaly physiological pigment such mica with titanium oxide or titanium oxide containing a coloring pigment and further laminating a silica layer or a powder having the capability of scattering light thereon, and when laminated with a silica layer, a difference between a refractive index of titanium oxide and that of silica is large, and strong reflection of light occurs on the interface between the two layers, so that the feeling of transparency is not satisfactory.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide an inorganic composite powder having a satisfactory covering capability and a feeling of transparency. Another object of the present invention is to provide a cosmetic blended with the inorganic composite powder which can cover such defects as blots and freckles on the human skin and insure a natural appearance.
The inorganic composite powder according to the present invention comprises two or more types of inorganic oxides having different refractive indexes respectively and sequentially laminated from the one with the highest refractive index at the bottom on a scaled substrate, wherein the difference in the refractive index between the utmost outer layer and adjoining inner layer is 0.6 or below.
The difference in refractive indexes of all pairs of adjoining two inorganic oxide layers is preferably 0.6 or below.
Further the inorganic composite powder according to the present invention comprises two or more types of inorganic oxides having different refractive indexes respectively and sequentially laminated from the one with the highest refractive index at the bottom on a scaled substrate, wherein a thickness of at least one of the second or higher inorganic oxide layers is within ±20% of the value d given by the equation:
d
=(&lgr;×
X
/4)

wherein &lgr; indicates a wavelength of visual light, X indicates an odd integer, and n indicates a refractive index of the inorganic oxide.
Said scaled substrate comprises preferably at least one of inorganic oxides selected from the group consisting of natural minerals such as mica, talc, and sericite; synthetic mica, synthetic sericite, plate-formed titanium oxide, plate-formed silica, plate-formed aluminum oxide, boron nitride, barium sulfate, and plate-formed titania and silica composite oxide.
The cosmetic according to the present invention is characterized in that said inorganic composite powder is blended therein and, the refractive index of the inorganic oxide used for forming the utmost outer layer of said inorganic composite powder is preferably 1.5 or below.
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention are described below.
A scaled substrate used in the present invention should preferably has an average particle diameter in the range from 2 to 20 &mgr;m and a thickness in the range from 0.05 to 1 &mgr;m. As the scaled substrate as described above, there can be enumerated such inorganic compounds as natural or synthetic mica, talc, sericite, and further plate-formed titanium oxide, plate-formed silica, plate-formed aluminum oxide, boron nitride, plate-formed barium sulfate, plate-formed titania silica composite oxide, but any other materials may be used so far as the materials have the size as described above.
The inorganic oxides which maybe used for coating the scaled substrate and refractive indexes are shown below.
Titanium oxide (2.50)
Zinc oxide (2.0)
Zirconium oxide (2.2)
Cerium oxide (2.2)
Tin oxide (2.0)
Thallium oxide (2.1)
Barium titanate (2.4)
Aluminum oxide (1.73)
Magnesium oxide (1.77)
Yttrium oxide (1.92)
Silica (1.45)
Magnesium fluoride (1.38)
magnesium carbonate (1.5)
Calcium fluoride (1.43)
In addition, a mixture of these inorganic oxides and an inorganic oxide which is a composite or a solid solution may be used for this purpose.
The inorganic composite powder according to the present invention is formed by laminating thereon two or more inorganic oxides having different refractive indexes respectively selected from those listed above from the one having a higher refractive index into two or more layers. The inorganic oxide is selected based on the covering capability required for the inorganic composite powder to be laminated therewith. To obtain an inorganic composite powder with the higher covering capability, it is preferable to use an inorganic oxide with higher refractive index such as, for instance, titanium oxide for forming the first layer. To obtain an inorganic composite powder with the lower covering capability, it is preferable to use an inorganic oxide with the intermediate covering capability such as aluminum oxide for forming the first layer.
Then, the second and higher layers are formed for lamination, and to suppress reflection of light and obtain the feeling of transparency, it is necessary that the difference of a refractive index of the inorganic oxide used for forming the utmost external layer and that of an inorganic oxide used for forming the adjoining inner layer is less than 0.6. The difference between the refractive indexes should preferably be

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