Drug – bio-affecting and body treating compositions – Anti-perspirants or perspiration deodorants
Reexamination Certificate
2001-09-10
2002-06-18
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Anti-perspirants or perspiration deodorants
C424S078020, C424S078080, C424S400000, C424S401000
Reexamination Certificate
active
06406684
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not applicable.
FIELD OF THE INVENTION
This invention is directed to underarm compositions, in particular to antiperspirants containing a mixture of an &agr;,&ohgr;-diene crosslinked silicone elastomer and a silicone rubber powder.
BACKGROUND OF THE INVENTION
Silicone rubber powders having an average particle diameter of 0.1-200 micron (&mgr;m) are disclosed in U.S. Pat. No. 5,628,989 (May 13, 1997), including their use in antiperspirants. Aqueous suspensions containing silicone rubber powders having an average particle diameter of 0.1-500 micron (&mgr;m) are disclosed in U.S. Pat. No. 5,928,660 (Jul. 27, 1999), including their use in antiperspirants. An antiperspirant powder consisting of an antiperspirant salt and a silicone rubber powder having an average particle diameter of 0.1-200 micron (&mgr;m) is disclosed in U.S. Pat. No. 6,126,927 (Oct. 3, 2000).
U.S. Pat. No. 5,654,362 (Aug. 5, 1997), while generally relating to &agr;,&ohgr;-diene crosslinked silicone elastomers, suggests that &agr;,&ohgr;-diene crosslinked silicone elastomers can be used as carriers for crosslinked silicone rubber particles, i.e., silicone rubber powders. While the '362 patent in Example III teaches using &agr;,&ohgr;-diene crosslinked silicone elastomers in antiperspirants, it fails to teach how to prepare an antiperspirant containing both &agr;,&ohgr;-diene crosslinked silicone elastomers and silicone rubber powders.
According to the present invention, and quite unexpectedly, it was discovered that new and improved results can be obtained when antiperspirants contain a ratio of 1:2 to 1:6 of the silicone rubber powder to the &agr;,&ohgr;-diene crosslinked silicone elastomer, i.e., one part silicone rubber powder to 2-6 parts of &agr;,&ohgr;-diene crosslinked silicone elastomer. When the ratio is less than 1:2, an oil layer is formed in roll-on applications. When the ratio is above 1:6, the viscosity of the roll-on becomes too high for practical application.
BRIEF SUMMARY OF THE INVENTION
This invention relates to an underarm composition containing as its basic components, (i) an antiperspirant or deodorant active ingredient, (ii) a vehicle, (iii) an emollient, and (iv) a blend of a silicone rubber powder and an &agr;,&ohgr;-diene crosslinked silicone elastomer. The silicone rubber powder and the &agr;,&ohgr;-diene crosslinked silicone elastomer are present in the blend in a weight ratio of 1:2 to 1:6, respectively.
Preferably, the underarm composition is anhydrous, and it may contain as an additional component (v) a wax.
These and other features of the invention will become apparent from a consideration of the detailed description.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
Not applicable.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term silicone rubber powder is intended to mean compositions prepared generally according to methods described in U.S. Pat. No. 4,742,142 (May 3, 1988).
Silicone rubber powders, sometimes referred to as E-Powders, are spherical particles of vulcanized silicone rubber, i.e., crosslinked polydimethylsiloxanes (PDMS), having a mean particle size distribution on the order of 0.1-200 &mgr;m. An aqueous emulsion process is used to prepare the silicone rubber powder as this process leads to a spherical shape for the particles, and it provides the desirable particle size distribution. In essence, the emulsion process consists of emulsifying a curable, liquid silicone elastomeric composition in water with one or more surface active agents followed by a curing step and finally removal of water. Inherent to the emulsion process are the spherical shape of the particles and a relatively good control of particle size distribution within a certain region.
Two curing reactions for crosslinking siloxane polymers are generally utilized, one being addition of a silicon hydride (≡SiH) to a vinyl functional siloxane in the presence of a platinum catalyst, i.e., hydrosilylation, and the other condensation of silanol functional siloxanes with reactive silicon. Polymers used to make silicone rubber powder are either OH or vinyl functional polymers, depending upon whether condensation or hydrosilylation is used for the crosslinking step. These polymers are usually of moderately low molecular weight (MW), such that their concomitant low viscosity make them easy to emulsify by conventional techniques. Polymers having viscosities under about 1000 cP (centipoise) are preferred for preparing silicone rubber powder.
Crosslinking agents can be practically any multifunctional reactive siloxane or silane that is soluble in the polymer. Silicon hydride (≡SiH) functional siloxanes are the crosslinkers of choice due to their high reactivity and the absence of byproducts. These can be either linear polymethylhydrogen siloxane or copolymers of polydimethylsiloxane polymethylhydrogen siloxane. The hydrosilylation reaction involving addition of ≡SiH to a vinyl functional siloxane has the advantage that no byproducts are formed. In contrast, copious amounts of H
2
are liberated from the condensation route involving reaction of ≡SiH with ≡SiOH.
The emulsification procedure is carried out using standard emulsion high shear equipment such as homogenizers or colloid mills. Surface active agents used can be either ionic or nonionic, or a combination of both, but nonionic is preferred. Preferred nonionic surfactants are alkyl ethoxylates. Levels of surfactant is on order of 0.5-5 percent by weight of the silicone polymer. It should be understood that the surface active agents remain with the silicone rubber powder upon removal of water.
Crosslinking in silicone rubber powders must occur after the particles have been formed. However, crosslinking will commence upon combining the three basic ingredients, (i) the functional polymer, (ii) the crosslinking agent, and (iii) the catalyst. Thus, some means must be used to ensure particle formation is complete prior to the onset of significant crosslinking. This can be accomplished by using catalyst inhibitors or by adding the catalyst after emulsification. In some cases, the emulsion is heated to increase the rate of crosslinking reactions. Once crosslinking is complete, the particles are harvested by removing water. Water removal can be accomplished by using processes like vacuum distillation or spray drying. In vacuum distillation, a mixer is used to provide heat and agitation under vacuum. Spray drying is the preferred method, however, as it is highly efficient and can be operated continuously.
As used herein, the term &agr;,&ohgr;-diene crosslinked silicone elastomer is intended to mean &agr;,&ohgr;-diene crosslinked silicone elastomers having no oxyalkylene units in their structure. They have been referred to generally in the art as non-emulsifying silicone elastomers, meaning that polyoxyalkylene units are absent. Otherwise, the &agr;,&ohgr;-diene crosslinked silicone elastomers suitable for use according to this invention are the compositions described in U.S. Pat. No. 5,654,362.
As described in detail in the '362 patent, the &agr;,&ohgr;-diene crosslinked silicone elastomers are prepared by reacting (A) an ≡Si—H containing polysiloxane of the formula R
3
SiO(R′
2
SiO)
a
(R″HSiO)
b
SiR
3
and optionally an ≡Si—H containing polysiloxane of formula HR
2
SiO(R′
2
SiO)
c
SiR
2
H or formula HR
2
SiO(R′
2
SiO)
a
(R″HSiO)
b
SiR
2
H where R, R′, and R″ are alkyl groups with 1-6 carbon atoms; a is 0-250; b is 1-250; and c is 0-250; with (B) an alpha,omega-diene of formula CH
2
═CH(CH
2
)
x
CH═CH
2
where x is 1-20. The reaction is conducted in the presence of a platinum catalyst and in the presence of (C) a low molecular weight silicone oil or other solvent. The reaction system is non-aqueous in contrast to the reaction system used to prepare the silicone rubber powder.
For mos
Fecht Cassandre Michelle
Starch Michael Stephen
Cesare James L. De
Dodson Shelley A.
Dow Corning Corporation
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