Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1999-05-22
2002-07-23
Jones, Dameron (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
Reexamination Certificate
active
06423322
ABSTRACT:
TECHNICAL FIELD
The present invention pertains to organopolysiloxane gels suitable for use in cosmetic applications.
BACKGROUND ART
Oganopolysiloxanes have been used in numerous cosmetic applications for many years. In some of these applications, for example, organopolysiloxanes such as silicone fluids have been employed either in their native form as oils for carriers for other cosmetic ingredients, or in the form of a variety of emulsions. In many of the latter cases, a surfactant is necessary in order to keep the silicone fluid in stable suspension or dispersion. Somewhat more recently, numerous cosmetic formulations have employed creams or pastes which include organopolysiloxane gels.
U.S. Pat. No. 5,654,362 discloses silicone gels prepared by reacting a linear, Si—H functional polysiloxane with an &agr;,&ohgr;-diene, for example 1,5-hexadiene, in the presence of a platinum hydrosilylation catalyst and a low molecular weight silicone oil. The reaction is continued until a gel is formed following which the silicone gel may be crumbled into a powder and used to thicken solvents, or by addition of further silicone oil, to form a silicone paste. The products are employed to thicken solvents such as silicone oils to a gel-like consistency. A variety of cosmetic products such as an anti-perspirants, deodorants, skin creams, etc., are disclosed. The use of highly flammable diene hydrocarbons in the preparation is a disadvantage. Moreover, creams formed from solid powders are said not to provide acceptable properties, as indicated by U.S. Pat. No. 4,980,167, wherein such formulations are said to suffer from lack of lubricity.
U.S. Pat. No. 5,859,069 discloses a gelatinous external skin treatment composition prepared from an organopolysiloxane elastomer powder having spherical particles with an average particle size of 1.0 to 15.0 &mgr;m, a silicone oil, and a polyether-modified silicone. The '069 patent indicates that prior formulations employing silicone resins are unsuitable for such uses, as they leave a filmy feeling on the skin. The polyether-modified silicone is disclosed as being absolutely necessary; and if amounts of less than 1.0% by weight are used, gelation becomes insufficient and the composition becomes unsuitable for use in cosmetics. Gelatinous external skin treatment compositions containing the spherical powder, 5-75% by weight of silicone oil, and 1-20% by weight of polyether-modified silicone are disclosed. Preparation of spherical elastomer particles is not straightforward. Moreover, the requirement for a polyether-modified silicone increases cost.
U.S. Pat. No. 5,811,487 like the '362 patent previously disclosed, describes low molecular weight siloxane fluids thickened with silicone elastomers prepared by reaction of Si—H functional siloxanes and an &agr;,&ohgr;-unsaturated hydrocarbon. However in the '487 patent, the Si—H siloxane is first partially reacted with a monoalkenyl functionalized polyether to provide polyether functionality. The polyether-functionalized organopolysiloxane is stated to be necessary by to prepare compositions containing dispersed water, consistent with the teachings of U.S. Pat. No. 5,859,069 discussed above.
U.S. Pat. No. 5,760,116 discloses a composition containing the hydrosilylation addition product of a linear alkenyl-functionalized polyorganosiloxane and an Si—H functional MQ resin. Monovinyl-functional linear polyorganosiloxanes are included in exemplified formulations as alkenyl-functionalized polyorganosiloxanes in addition to divinyl-functional polyorganosiloxanes. Uniform liquid compositions formed by first preparing a gel from these ingredients, and then dispersing the gel in a further silicone having a viscosity below 1000 centistokes is disclosed. Cosmetic compositions containing these silicone compositions are also disclosed.
U.S. Pat. No. 5,854,336 discloses a process for preparing cosmetic products which involves feeding a silicone elastomer composition consisting of a silicone rubber and a carrier fluid into a reactor, mixing the composition in the reactor, delivering the composition from the reactor to a high pressure pump, and from there into a device for reducing the particles of rubber into smaller sizes. The device for reducing particle size is preferably a high pressure feed homogenizer, most preferably a sonolator. Use of high pressure pumps and devices such as sonolators increase the expense of the product.
EP 0790 055 A1 discloses compositions containing a partially reticulated elastomeric organopolysiloxane and a fatty component such as a triglyceride for use in skin care or make-up formulas. What is meant by “partially reticulated” is not defined in the specification, which refers to U.S. Pat. No. 5,266,321 for its description of suitable organopolysiloxanes.
Examples of cosmetic formulations employing silicone gels are also disclosed in International PCT Applications WO97/44010; WO98/18438; WO98/00105; WO98/00104; WO98/00103; WO98/00102, and like patents. It can be clearly seen from such patents that the range of formulations includes antiperspirants, both liquid and solid, facial creams, moisturizers, and other products. It should also be apparent from a review of these references that there are considerable differences between the variety of organosilicone gels. In particular, some of these gels provide an unacceptable oily feeling when such is not desired. Other gels are more difficult to produce, and unnecessarily increase the cost of formulation. It would be desirable to be able to produce gels in a simple fashion from well-recognized and essentially non-toxic ingredients, to produce a product which avoids the stringiness of other gels, and which can be emulsified without the use of extremely high pressure devices such as sonolators and the like.
SUMMARY OF THE INVENTION
It has now been unexpectedly discovered that organopolysiloxane gels containing a low viscosity and preferably volatile silicone oil may be easily prepared by the hydrosilylation reaction of a vinyl functional MQ resin with an Si—H functional poly(methylhydrogen)dimethylsiloxane in the presence of the low viscosity fluid and a small amount of platinum hydrosilylation catalyst. It has also been discovered that addition of relatively small amounts of hydrosilylation catalyst poisons such as organosulphur compounds, particularly mercaptoalkyl organopolysiloxanes, produces compositions which retain their stability over longer periods of time than when the organosulphur compounds are not employed. The resulting gels are non-stringy gels which may be easily homogenized to form a stable cream or paste without the use of high pressure or other complex mixing arrangements.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The organopolysiloxane gels of the subject invention contain a low viscosity and preferably volatile silicone oil, intimately associated with a gel matrix produced by the cross-linking of a vinyl functional MQ resin with an Si—H functional organopolysiloxane which contains Si—H functionality distributed along its backbone rather than at the termini.
The low viscosity and preferably volatile organopolysiloxane may be a low molecular weight oligomeric polydialkylsiloxane, or a cyclic siloxane. Most preferably, the low viscosity organopolysiloxane is an oligomeric polydimethylsiloxane or a cyclic polydimethylsiloxane. Other alkyl, aryl, alkaryl, and aralkyl groups are also acceptable, of course, for example, phenyl groups, benzyl groups, C
1
-C
18
alkyl groups, and the like. However, because of cost considerations and the ease of formulation, organopolysiloxanes with methyl groups attached to the silicon atoms are highly preferred. Most preferably, the organopolysiloxanes are linear trimethylsilyl terminated polydimethylsiloxanes having on average from 2 to 50 silicon atoms in the organopolysiloxane backbone inclusive of the trimethylsilyl end groups. If volatility is desired, the number of silicon atoms should be greatly restricted, for example, to below 10, and preferably below 6. However, if relatively low viscosity
Brooks & Kushman P.C.
Jones Dameron
Wacker Silicones Corporation
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