Polar solvent-in-oil emulsions and multiple emulsions

Details Polar solvent-in-oil emulsions and multiple emulsions Polar solvent-in-oil emulsions and multiple emulsions

2000-09-08

2001-04-24

Foelak, Morton (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

C424S078030, C514S725000, C524S261000, C524S379000, C524S386000, C524S387000, C524S589000

Reexamination Certificate

active

06221927

ABSTRACT:

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 (i) polar solvent-in-oil emulsions PS
1
/O, (ii) polar solvent-in-oil-in-water multiple emulsions PS
1
/O/W, and (iii) polar solvent-in-oil-in-polar solvent multiple emulsions PS
1
/O/PS
2
. In particular, these emulsions contain a non-aqueous polar solvent(s).
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,948,855 (Sep. 7, 1999) describes certain water-in-oil emulsions W
1
/O and multiple emulsions W
1
/O/W
2
which can be prepared with crosslinked elastomeric silicone polyethers as an emulsifier. These crosslinked elastomeric silicone polyethers and methods for their preparation are described in U.S. Pat. No. 5,811,487 (Sep. 22, 1998) and in U.S. Pat. No. 5,889,108 (Mar. 30, 1999). These patents are assigned to the same assignee as the present invention.
However, none of the common assignee's patents describe the use of the crosslinked elastomeric silicone polyethers as emulsifiers for preparing non-aqueous polar solvent-in-oil emulsions PS
1
/O and multiple emulsions PS
1
/O/W and PS
1
/O/PS
2
. The advantage of emulsions of the type PS
1
/O, PS
1
/O/W, and PS
1
/O/PS
2
, is that they can be used to deliver polar actives such as Vitamin C or activated antiperspirant salts such as aluminum chlorohydrate and aluminum-zirconium trichlorohydrate, which are known to have much better chemical stability in non-aqueous polar solvents such as propylene glycol than in water.
BRIEF SUMMARY OF THE INVENTION
In a first embodiment, the invention relates to a composition which is a non-aqueous polar solvent-in-oil emulsion containing a non-aqueous polar solvent phase dispersed in a silicone oil continuous phase by an emulsifier.
In a second embodiment, the invention relates to a composition which is a non-aqueous polar solvent-in-oil-in-water multiple emulsion of the type PS
1
/O/W which contains a non-aqueous polar solvent phase PS
1
dispersed in a silicone oil as a first continuous phase of a primary emulsion PS
1
/O by an emulsifier. The primary emulsion PS
1
/O is dispersed in a second continuous aqueous phase W to form the multiple emulsion PS
1
/O/W.
In a third embodiment, the invention relates to a composition which is a non-aqueous polar solvent-in-oil-in-non-aqueous polar solvent multiple emulsion of the type PS
1
/O/PS
2
which contains a non-aqueous polar solvent phase PS
1
dispersed in a silicone oil as a first continuous phase of a primary emulsion PS
1
/O by an emulsifier. The primary emulsion PS
1
/O is dispersed in a second continuous non-aqueous polar solvent phase PS
2
to form the multiple emulsion PS
1
/O/PS
2
.
In the three embodiments, the emulsifier is a crosslinked elastomeric silicone polyether constituting polymeric molecules crosslinked together to form a gel consisting of three-dimensional molecular polymeric networks containing tens, hundreds, and thousands of crosslinking units between and among the polymeric molecules. The crosslinked elastomeric silicone polyether contains and is swollen by about 65 to about 98 percent by weight of a silicone oil.
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
Emulsions are composed of droplets of one liquid dispersed in a second liquid. Multiple emulsions are composed of droplets of one liquid dispersed in a second liquid, which is then dispersed in a final continuous phase. Generally, the internal droplet phase will be miscible with or identical to the final continuous phase.
For example, in a water-in-oil-in-water multiple emulsion W/O/W, the internal phase and the external phase are both aqueous. In a non-aqueous polar solvent-in-oil-in-water multiple emulsion PS
1
/O/W, the internal phase is a non-aqueous polar solvent and external phase is aqueous. In a non-aqueous polar solvent-in-oil-in-non-aqueous polar solvent multiple emulsion PS
1
/O/PS
2
, the internal phase and the external phase are both non-aqueous polar solvents.
For the system PS
1
/O/W in which the final continuous phase is aqueous, the primary emulsion is polar solvent-in-oil emulsion PS
1
/O, which is then emulsified into the final aqueous phase W. For the system PS
1
/O/PS
2
in which the final continuous phase is a polar solvent, the primary emulsion is polar solvent-in-oil emulsion PS
1
/O, which is then emulsified into the final polar solvent phase PS
2
.
For the purpose of clarity, and in accordance with recognized standards of nomenclature used for a PS
1
/O/W system, the oil phase of the primary emulsion is designated as O, and the primary emulsion is designated PS
1
/O. Primary emulsion PS
1
/O includes polar solvent phase PS
1
. After primary emulsion PS
1
/O has been further dispersed in the final aqueous phase W, this multiple emulsion is designated PS
1
/O/W. For a PS
1
/O/PS
2
system, the oil phase of the primary emulsion is again O, and the primary emulsion is PS
1
/O. Primary emulsion PS
1
/O includes polar solvent phase PS
1
. After primary emulsion PS
1
/O has been further dispersed in the final and second polar solvent phase PS
2
, this multiple emulsion is designated as PS
1
/O/PS
2
.
Crosslinked elastomeric silicone polyethers which are used in forming these emulsions, and methods for preparing these crosslinked elastomeric silicone polyethers are described in detail in the common assignee's U.S. Pat. No. 5,811,487, incorporated herein by reference.
Generally, such crosslinked elastomeric silicone polyethers are prepared by reacting an ≡Si—H containing polysiloxane (A) and a mono-alkenyl polyether (B) in the presence of a platinum catalyst, until an ≡Si—H containing siloxane with polyether groups (C) is formed. The ≡Si—H containing siloxane with polyether groups (C) is then reacted with an unsaturated hydrocarbon (D) such as an alpha, omega-diene, in the presence of a solvent (E) and a platinum catalyst, until a silicone elastomer is formed by crosslinking and addition of ≡SiH across double bonds in the alpha, omega-diene (D).
These crosslinked elastomeric silicone polyethers can be generally described as constituting polymeric molecules which are crosslinked together to form gels consisting of three-dimensional molecular polymeric networks containing tens, hundreds, and thousands of crosslinked units between and among the polymeric molecules. Typically, these crosslinked elastomeric silicone polyethers contain and are swollen by 65 to 98 percent by weight of an oil.
Both U.S. Pat. Nos. 5,811,487 and 5,889,108 contain extensive lists of appropriate oils which can be used, among which are, for example, (i) volatile polydimethylsiloxanes such as hexamethyldisiloxane, octamethyltrisiloxane, and decamethylcyclopentasiloxane, (ii) nonvolatile polydimethylsiloxanes having a viscosity generally in the range of about 5 to about 1,000 centistoke (mm
2
/s), and (i) fragrances such as musk and myrrh.
Organic oils such as natural oils derived from animal, vegetable, or mineral sources, are also suitable. Modern cosmetic oils, for example, are most representative, and among common organic oils known to be safe for cosmetic purposes are almond oil, apricot kernel oil, avocado oil, cacao butter (theobroma oil), carrot seed oil, castor oil, citrus seed oil, coconut oil, corn oil, cottonseed oil, cucumber oil, egg oil, jojoba oil, lanolin oil, linseed oil, mineral oil, mink oil, olive oil, palm kernel oil, peach kernel oil, peanut oil, rapeseed oil, safflower oil, sesame oil, shark liver oil, soybean oil, sunflower seed oil, sweet almond oil, tallow (beef) oil, tallow (mutton) oil, turtle oil, vegetable oil, whale oil, and wheat germ oil.
While the term non-aqueous polar solvent is intended to include solvents generally, when the emulsions and multiple emulsions are intended for personal care application, then the non-aqueous polar solvent should be one recognized

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