Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1999-07-14
2001-08-28
Dudash, Diana (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S489000, C424S063000, C424S069000, C423S324000, C423S348000, C524S588000
Reexamination Certificate
active
06280749
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a powder of cured fluorosilicone rubber particles suitable as an additive to a variety of compositions such as paints, synthetic resins, synthetic and natural rubbers, polishing agents, surface-release agents and cosmetic or toiletry preparations. This invention also relates to cosmetic preparations compounded with such a powder.
Fine particles of a cured silicone rubber are known in the prior art as disclosed, for example, in Japanese Patent Publications 3-30620, 4-17986, 4-55611, 6-2820, 6-2821 and 6-11795 and elsewhere. Proposals are made for the application thereof as an additive to a thermosetting epoxy resin, synthetic rubber, pigment, coating composition and others. Furthermore, a proposal is made in Japanese Patents Kokai 7-258026, 7-258027, 8-259419, 8-310915, 8-319215 and 8-319218 for the application of cured silicone rubber particles as an additive to a variety of cosmetic products.
Cosmetic products prepared by compounding conventional cured silicone rubber particles have a serious problem. While it is sometimes the case that a cosmetic preparation is formulated with an oily ingredient such as low molecular weight silicones having cyclic or linear molecular structures including octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and octamethyltrisiloxane and oily hydrocarbon compounds including liquid paraffin and isoparaffin, namely, these oily ingredients are absorbed by the cured silicone rubber particles resulting in swelling of the particles and consequently leading to a decrease in the opacity of the cosmetic layer on the human skin rendering the complexion of the base skin as see-through more or less. Moreover, the rubber particles in the cosmetic finishing layer on the skin are subject to migration under perspiration or by the movement of the face accompanying the coloring agent in the cosmetic preparation resulting in heavy collapsing of the makeup finish.
It is eagerly desired therefore to develop novel and improved cured silicone rubber particles suitable as additives to cosmetic preparations to be free from the above described problems of conventional cured silicone rubber particles without decreasing the advantages to be obtained by the formulation with fine cured silicone rubber particles.
SUMMARY OF THE INVENTION
In view of the above described problems in the conventional cured silicone rubber particles as an ingredient in cosmetic preparations, the inventors have conducted extensive investigations to obtain fine particles of a cured silicone rubber arriving at an unexpected discovery that the fine cured silicone rubber particles defined below well meet the requirements as an additive to cosmetic preparations.
Thus, the present invention provides fine particles of a cured fluorosilicone rubber consisting of three types of organosiloxane units represented by the unit formulas:
R
1
R
2
SiO
2/2
; (1)
R
2
2
SiO
2/2
(2)
and
R
2
3
SiO
1/2
, (3)
In which R
1
is a perfluoroalkyl-substituted alkyl group of the formula R
f
(CH
2
)
a
—, R
f
being a perfluoroalkyl group having 1 to 20 carbon atoms or, preferably, a trifluoromethyl group and the subscript a being a positive integer not exceeding 6 or, preferably, 2, and R
2
is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms with the proviso that the molar ratio of R
1
to (R
1
+R
2
) is in the range from 0.05 to 0.5.
The cured fluorosilicone rubber particles defined above, preferably, have an average particle diameter in the range from 0.1 to 100 &mgr;m and a rubber hardness of 5 to 90 in the JIS A scale specified in JIS K 6301, when used as an ingredient in cosmetic preparations.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As is described above, the cured fluorosilicone rubber constituting the inventive cured silicone rubber particles is a polyorganosiloxane consisting of three types of the organosiloxane units including two difunctional units expressed by the unit formulas (1) and (2) and a monofunctional units expressed by the unit formula (3) described above.
The difunctional units of the first type are represented by the unit formula R
1
R
2
SiO
2/2
, in which R
1
is a perfluoroalkyl-substituted alkyl group which is preferably a 3,3,3-trifluoropropyl group and R
2
is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. The perfluoroalkyl group R
f
forming a part of the group R
1
is exemplified by perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluorohexyl, perfluoroheptyl, perfluorooctyl, perfluorodecyl, perfluorododecyl, perfluorotetradecyl, perfluorohexadecyl, perfluorooctadecyl and perfluoroeicosyl groups, of which perfluoromethyl group is preferred with the subscript a, which is a positive integer of 1 to 6, equal to 2 forming a 3,3,3-trifluoropropyl group as R
1
. This is because organosilicon compounds having a silicon-bonded 3,3,3-trifluoropropyl group have good availability as compared with organosilicon compounds having other types of perfluoroalkyl-substituted alkyl groups in the molecule in addition to the advantage that the fluorosilicone rubber particles according to this preference can impart good lubricity and smoothness to the cosmetic finish with the cosmetic preparation formulated with the cured silicone rubber particles.
The silicon-bonded group denoted by R
2
in each of the three types of the organosiloxane units is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms exemplified by alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and eicosyl groups, cycloalkyl groups such as cyclopentyl and cyclohexyl groups, alkenyl groups such as vinyl and allyl groups and aryl groups such as phenyl and tolyl groups. In particular, it is preferable that all or at least 90% by moles of the groups denoted by R
2
are methyl groups. When the number of carbon atoms in the group R
2
, similarly to the perfluoroalkyl group R
f
forming the group R
1
, exceeds 20, a decrease is caused in the lubiricity and surface-releasability of the fluorosilicone rubber particles.
It is important that the organopolysiloxane forming the cured fluorosilicone rubber particles contains the groups R
1
and R
2
in a specified molar proportion determined by the molar ratio of R
1
:(R
1
+R
2
) which should be in the range from 0.05 to 0.5 or, preferably, from 0.1 to 0.4 or, more preferably, from 0.15 to 0.35. When this molar ratio is too small, the fluorosilicone rubber particles do not have fully decreased affinity to oily materials so as to be swollen with the oily ingredient in a cosmetic preparation. When this molar ratio is too large, on the other hand, the rubber particles are deficient in the lubricity and surface-releasability.
When the intended application of the inventive cured fluorosilicone rubber particles is as an additive in a cosmetic preparation, the particles should have an average particle diameter in the range from 0.1 to 100 &mgr;m or, preferably, from 1 to 50 &mgr;m or, more preferably, from 3 to 20 &mgr;m. When the average particle diameter is too small, the particles are deficient in the lubricity and surface-releasability while, when the average particle diameter is too large, the skin surface finished with a cosmetic preparation containing the particles would necessarily feel rough and sandy.
Further it is a desirable condition for the cured fluorosilicone rubber particles as an additive to a cosmetic preparation that the rubber hardness thereof in the JIS A scale is in the range from 5 to 90 or, preferably, from 10 to 80 or, more preferably, from 20 to 70. When the hardness of the particles is too low, the particles are deficient in lubricity and surface-releasability while, when the rubber hardness is too high, the skin surface finished with a cosmetic preparation containing the particles would necessarily feel rough and sandy.
The particle configuration of the inventive cured fluorosilicone
Inokuchi Yoshinori
Kuwata Satoshi
Omura Naoki
Dudash Diana
Haghighatian Mina
Millen White Zelano & Branigan P.C.
Shin-Etsu Chemical Co. , Ltd.
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