Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1994-06-10
2002-10-08
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S063000, C424S069000
Reexamination Certificate
active
06461621
ABSTRACT:
The present invention relates to a solid cosmetic composition in the form of a molded powder cake comprising as a principal particulate charge hollow microspheres having one or more open or closed cavities.
The invention also concerns a process for producing such a molded powder cake.
It is known that certain makeup products in the form of solid powder cosmetic products, such as eyelid makeup or cheek makeup are generally provided in the form of molded powder cakes. A “molded powder cake” is one which is produced by mixing a solid particulate phase and a binding agent (generally a fatty phase) in a solvent, so as to obtain a fluid paste, distributing the said fluid paste by pouring it into appropriate containers (dishes or cups) and then evaporating the solvent. The advantages of molded powder cakes are on the one hand the possibility of introducing various ingredients into the composition owing to the choice of the solvent selected, and on the other hand, the free choice of the form and material of the cup or dish, which permits multiple presentations of the final products.
In the preparation of molded powder cakes, several kinds of disadvantages are observed: a shrinkage phenomenon which results in the cup or dish not being completely filled (which is discouraging to the consumer); an irregular appearance of the surface of the product (a grooved, cracked or cratered appearance at the time of evaporation); and formation of a film of the binding agent on the surface.
Various solutions have been proposed to remedy these disadvantages.
In EP patent application No. 0038645, the cup, the open upper portion of which is fitted with a removable lid, is filled, in inverse position, by the base which is constituted by a support in the form of a grid. After evaporation of the solvent, the base is sealed with an appropriate base plate. In this manner, the irregular appearance of the surface through which is produced the evaporation of the solvent, as well as the shrinkage phenomenon, are not visible to the consumer. This procedure exhibits the disadvantage of requiring a special cup with the base support in the form of a grid.
U.S. Pat. No. 4,804,538 envisages the use of a cup the base of which has openings for filling with the fluid paste through the base, in non-inverse position, using injection nozzles fed under pressure, while the solvent is evaporated through the upper portion of the cup linked to a vacuum pump. This procedure requires complex and costly equipment.
In EP patent application No. 0165137 there is proposed the use of, as a binder, a bentonite treated with a cationic surfactant. Since this binder is not soluble in the solvent, the formulation of a surface film of the binding agent is avoided. However, the problem of shrinkage is not resolved and the feel of the resulting product is not satisfactory.
DE 332701 patent describes a process for preparing molded powder cakes in which the various operations of mixing the ingredients with an excess of solvent, molding and evaporation of solvent are effected hot increase the production costs. According to this patent, the condition of the surface of the molded powder cake is improved. However, the shrinkage phenomenon is not avoided.
It has now been discovered that the addition, as a constituent of the particulate charge, of a small weight amount of hollow microspheres having one or more open or closed cavities, permits the preparation, with a significant reduction of the shrinkage phenomenon, of molded powder cakes having a satisfactory surface condition and disintegration.
It has also been evidenced that the use of these novel constituents of the particulate charge permits the preparation at a moderate temperature and with a choice of various solvents, which indeed provides advantages on the economic level.
The invention thus relates to a solid cosmetic composition in the form of a molded powder cake constituted by a solid particulate phase and optionally a binder agent and conventional additives, wherein the particulate phase includes hollow microspheres having one or more open or closed cavities.
It has been noted that by practicing the invention a solid powder having a satisfactory surface condition and disintegration and a very small amount of shrinkage can be obtained. It will be noted here, as is well known to the specialists, that molded powder cakes have the appearance and the properties of a coherent solid product, having principally a defined surface as opposed to free powders (free flowing). Since it is a question of coherent solid products, their use requires the removal of a certain amount of powder by disintegration using an appropriate applicator.
The microspheres employed here are particles of essentially spherical form having generally a diameter less than 70 &mgr;m (preferably less than 40 &mgr;m).
The microspheres are produced from any appropriate inorganic or organic material, compatible with a use on the skin, that is, nonirritating and nontoxic.
The microspheres of an organic polymer material possessing a single closed cavity containing a gas, such as a hydrocarbon (for example, isobutane), can be prepared in accordance with known procedures, for example, those described in U.S. Pat. No. 3,615,972 and in EP patent application 0056219.
The organic microspheres are produced, for example, from polymers or copolymers derived from acids, amides or esters (monomers) having ethylenic unsaturation, from urea-formaldehyde polymers, from polymers or copolymers of vinylidene chloride, etc.
Mention can be made, as an example, of microspheres made from acrylate or methyl methacrylate polymers or copolymers, or even from vinylidene chloride/acrylonitrile copolymers.
Representative vinylidene chloride/acrylonitrile copolymers include principally those which contain, by weight, from 20 to 60 percent of units derived from vinylidene chloride, from 20 to 60 weight percent of units derived from acrylonitrile and from 0 to 40 weight percent of other units such as units derived from an acrylic or styrene monomer.
There can even be used crosslinked acrylic polymers or copolymers, for example, polymers the carboxylic groups of which are partially esterified with diols serving as crosslinking agents.
These materials can serve as a base for the preparation of microporous microspheres.
When the hollow microspheres employed in accordance with the invention are microporous microspheres, their range corresponds, for example, to a specific surface of at least 0.5 m
2
/g, and in particular of at least 1 m
2
/g. There is no upper limit (other than that resulting from the possibility of practical production of the microspheres having a very high porosity) for the specific surface. The specific surface can extend, for example, to 1000 m
2
/g or even higher, for example, up to a few hundreds of thousands of m
2
/g.
Particularly preferred are principally the microporous microspheres sold by Dow Corning under the trade name “POLYTRAP Q5-6603”, or those sold by Seppic under the trade name “MICROPEARL M” or “MICROPEARL M100”, as well as hollow microspheres having a closed cavity sold under the trade name “EXPANCEL” by Kemanord Plast.
Representative microspheres derived from an inorganic material, include, for instance, silica microspheres having open porosity or, preferably, hollow, such as for example those sold under the trade name “SILICA BEADS S700” by Miyoshi Kasei Inc.
Preferably, microspheres having a density (more exactly a volume mass) lower than 0.7 g/cm
3
, for example between 0.01 and 0.7 g/cm
3
are employed. The volume mass of the powders depend on their degree of packing. The volume masses given here correspond to the volume mass measured in accordance with the German standard DIN 53194, after ten packings.
The weight amount of the hollow microspheres in the molded powder cake ranges generally from 0.2 to 15 percent relative to the total weight of the composition with the solvent (fluid paste).
Concerning the amount of the hollow microspheres in the dried final composition, it can vary generally from 0.1 to 50 percent, preferabl
DeFossez Béatrice
Gagnebien Didier
Lecomte Sophie
L'Oreal
Nixon & Vanderhye P.C.
Page Thurman K.
Tran S.
LandOfFree
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