Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Reexamination Certificate
2000-03-15
2002-01-01
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
C424S401000, C424S065000, C424S489000
Reexamination Certificate
active
06335037
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to cosmetics such as foundations, powders and makeup cosmetics, improved in spreadability and inunctionability.
2. Description of the Prior Art
Cosmetics mixed with powders are conventionally in wide use. These, however, have a poor spreadability and inunctionability especially to the skin, and are sought to be improved in such properties. To cope with such a demand, proposed are an inorganic composite powder surface-treated with a fluorine compound (see Japanese Laid-open Publication (Kokai) No. 6-79163), a powder surface-treated with methylhydrogenpolysiloxane or the like (see Japanese Laid-open Publication (Kokai) No. 5-112430), a hydrophobic powder surface-coated with an acrylic silicone type graft copolymer (see Japanese Laid-open Publication (Kokai) No. 5-339125), an extender pigment comprising potassium titanate coated with a metal oxide (see Japanese Laid-open Publication (Kokai) No. 5-163117), a chitosan powder surface-treated with hydrogenpolysiloxane (see Japanese Laid-open Publication (Kokai) No. 5-86102), a pigment comprising nitride microscopic lamellar substrates coated with a dye/metal oxide (see Japanese Laid-open Publication (Kokai) No. 5-279594), a flaky silica (see Japanese Laid-open Publication (Kokai) No. 6-87720), an ultrafine powder of collagen fibers (see Japanese Laid-open Publication (Kokai) No. 6-107522), a titanium oxide compound having photochromic properties (see Japanese Laid-open Publication (Kokai) No. 5-17152), and a polyamide powder of spherical fine particles (see Japanese Laid-open Publication (Kokai) No. 5-70598). These powders, however, have disadvantages that they not only have an insufficient spreadability to the skin but also have an unstable quality because of a difficulty in manufacture.
A makeup cosmetic is also proposed which has been mixed with polymethylsilasesquioxane as a silicone resin powder (see Japanese Laid-open Publication (Kokai) No. 63-297313). In the case of this cosmetic, it is a little improved in spreadability but has a poor inunctionability.
Silicone rubber powder is also known as a cosmetic powder. This powder has a good softness in itself, but can not improve the spreadability or inunctionability when mixed in cosmetics.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome the disadvantages the prior art has had as stated above, and to provide a cosmetic improved in spreadability and inunctionability.
To achieve the above object, the present invention provides a cosmetic comprising spherical hydrophobic fine silica particles having an average particle diameter of from 0.01 to 5 &mgr;m, which are obtained by introducing an R
2
SiO
3/2
unit (wherein R
2
represents a monovalent hydrocarbon group having 1 to 20 carbon atoms) to the surfaces of hydrophilic fine silica particles comprising an SiO
2
unit to obtain hydrophobic fine silica particles, and introducing an R
1
3
SiO
1/2
unit (wherein R
1
's may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms) to the surfaces of the resultant hydrophobic fine silica particles to make the particles more hydrophobic.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Spherical Hydrophobic Fine Silica Particles
The spherical hydrophobic fine silica particles used in the cosmetic of the present invention is a product obtained by introducing an R
2
SiO
3/2
unit (wherein R
2
represents a monovalent hydrocarbon group having 1 to 20 carbon atoms) to the surfaces of hydrophilic fine silica particles comprising an SiO
2
unit to obtain hydrophobic fine silica particles, and introducing an R
1
3
SiO
1/2
unit (wherein R
1
's may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms) to the surfaces of the resultant hydrophobic fine silica particles to make the particles more hydrophobic. From the viewpoint of an improvement in spreadability and inunctionability, the spherical hydrophobic fine silica particles thus obtained must have an average particle diameter within the range of from 0.01 to 5 &mgr;m, and preferably from 0.05 to 1 &mgr;m. If their average particle diameter is smaller than 0.01 &mgr;m, the cosmetic may have a poor spreadability, and, if larger than 5 &mgr;m, a poor inunctionability.
The monovalent hydrocarbon group represented by R
2
in the R
2
SiO
3/2
unit may include, e.g., alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl; aryl groups such as phenyl, tolyl and naphthyl; aralkyl groups such as benzyl and phenetyl; alkenyl groups such as vinyl, allyl, hexenyl and cyclohexenyl; and any of these groups at least part of hydrogen atoms of which has been substituted with a halogen atom such as a fluorine atom, as exemplified by a trifluoromethyl group and a heptadecafluorodecyl group. Preferably, R
2
includes methyl, ethyl, propyl and butyl groups.
The monovalent hydrocarbon group represented by R
1
in the R
1
3
SiO
1/2
unit may include, e.g., alkyl groups such as methyl, ethyl, propyl, butyl, pentyl and hexyl. Preferably, R
1
includes methyl, ethyl, propyl and butyl groups.
Specifically, the present spherical hydrophobic fine silica particles are produced through the following steps:
the steps of subjecting at least one compound selected from the group consisting of a tetrafunctional silane compound represented by the general formula (I):
Si(OR
3
)
4
(I)
wherein R
3
's may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms, a partial hydrolysis-condensation product thereof and a mixture of these, to hydrolysis and condensation in a mixed solvent of water and a hydrophilic organic solvent (e.g., methanol or ethanol) containing a basic substance such as ammonia or an organic amine, to prepare a hydrophilic solvent dispersion of hydrophilic fine silica particles, adding water to the resultant dispersion, and thereafter evaporating the hydrophilic organic solvent to convert the dispersion into an aqueous dispersion to hydrolyze the remaining alkoxyl groups completely;
the step of adding to the resultant aqueous dispersion of hydrophilic fine silica particles at least one compound selected from the group consisting of a trifunctional silane compound represented by the general formula (II):
R
2
Si(OR
4
)
3
(II)
wherein R
2
represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R
4
's may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms, and a partial hydrolysis-condensation product thereof, to treat the hydrophilic fine silica particle surfaces with it to obtain hydrophobic fine silica particles, thus the R
2
SiO
3/2
units being introduced onto the surfaces of the hydrophilic fine silica particles comprising SiO
2
units to produce hydrophobic fine silica particles;
the step of converting the resultant aqueous dispersion of hydrophobic fine silica particles into a ketone solvent dispersion by adding a ketone solvent followed by evaporation of water; and
the step of adding to the resultant hydrophobic fine silica particle ketone solvent dispersion at least one compound selected from the group consisting of a silazane compound represented by the general formula (III):
R
1
3
SiNHSiR
1
3
(III)
wherein R
1
's may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms, and a monofunctional silane compound represented by the general formula (IV):
R
1
3
SiX (IV)
wherein R
1
's are as defined in the general formula (III), and X represents a hydroxyl group or a hydrolyzable group, to allow to react with silanol groups remaining on the hydrophobic fine particle surfaces, thereby the silanol groups being trialkylsilylated, i.e., the R
1
3
SiO
1/2
units being introduced to the surfaces of the hydrophobic fine silica particles.
The spherical hydrophobic fine silica particles thus finally ob
Ichinohe Shoji
Kudo Muneo
Yamamoto Akira
Dodson Shelley A.
George Konata
Pillsbury & Winthrop LLP
Shin-Etsu Chemical Co. , Ltd.
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