United States Patent:  6,080,394

Assignee:  Dow Corning Corporation (Midland, MI)

Filed:  November 8, 1999

One composition 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. A second composition is a non-aqueous polar solvent-in-oil-in-water multiple emulsion of the type PS₁ /O/w which contains a non-aqueous polar solvent phase PS₁ dispersed in a silicone oil as a first continuous phase of a primary emulsion PS₁ /O by an emulsifier. The primary emulsion PS₁ /O is dispersed in a second continuous aqueous phase W to form multiple emulsion PS₁ /O/W. A third composition is a non-aqueous polar solvent-in-oil-in-non-aqueous polar solvent multiple emulsion of the type PS₁ /O/PS₂ which contains a non-aqueous polar solvent phase PS₁ dispersed in a silicone oil as a first continuous phase of a primary emulsion PS₁ /O by an emulsifier. The primary emulsion PS₁ /O is dispersed in a second continuous non-aqueous polar solvent phase PS₂ to form multiple emulsion PS₁ /O/PS₂.

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 PS₁ /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 PS₁ /O/PS₂, the internal phase and the external phase are both non-aqueous polar solvents.

For the system PS₁ /O/W in which the final continuous phase is aqueous, the primary emulsion is polar solvent-in-oil emulsion PS₁ /O, which is then emulsified into the final aqueous phase W.

For the system PS₁ /O/PS₂ in which the final continuous phase is a polar solvent, the primary emulsion is polar solvent-in-oil emulsion PS₁ /O, which is then emulsified into the final polar solvent phase PS₂.

For the purpose of clarity, and in accordance with recognized standards of nomenclature used for a PS₁ /O/W system, the oil phase of the primary emulsion is designated as O, and the primary emulsion is designated PS₁ /O. Primary emulsion PS₁ /O includes polar solvent phase PS₁. After primary emulsion PS₁ /O has been further dispersed in the final aqueous phase W, this multiple emulsion is designated PS₁ /O/W. For a PS₁ /O/PS₂ system, the oil phase of the primary emulsion is again O, and the primary emulsion is PS₁ /O. Primary emulsion PS₁ /O includes polar solvent phase PS₁. After primary emulsion PS₁ /O has been further dispersed in the final and second polar solvent phase PS₂, this multiple emulsion is designated as PS₁ /O/PS₂.

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 .tbd.Si--H containing polysiloxane (A) and a mono-alkenyl polyether (B) in the presence of a platinum catalyst, until an .tbd.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 .tbd.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. No. 5,811,487 and U.S. Pat. No. 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.sup.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 as being cosmetically acceptable. Representative of some cosmetically acceptable non-aqueous polar solvents which can be used are, for example, monohydroxy alcohols such as ethyl alcohol and isopropyl alcohol; diols and triols such as propylene glycol and glycerol, respectively; glycerol esters such as glyceryl triacetate (triacetin), glyceryl tripropionate (tripropionin), and glyceryl tributyrate (tributyrin); and polyglycols such as polyethylene glycol. In applications other than personal care, these and other more suitable types of non-aqueous polar solvents can be employed.

In using crosslinked elastomeric silicone polyethers for preparing non-aqueous polar solvent-in-oil emulsions consisting of a non-aqueous polar solvent disperse phase and an oil continuous phase, the non-aqueous polar solvent phase may contain a non-aqueous polar solvent soluble active ingredient, and the oil phase may contain an oil soluble active ingredient.

Some representative non-aqueous polar solvent soluble active ingredients for the non-aqueous polar solvent phase of the non-aqueous polar solvent-in-oil emulsion and multiple emulsion are (i) non-aqueous polar solvent soluble Vitamins, (ii) non-aqueous polar solvent soluble drugs including activated antiperspirant salts such as aluminum chlorohydrate and aluminum-zirconium trichlorohydrate, or (iii) .alpha.-hydroxy acids such as glycolic acid, lactic acid, tartaric acid, and citric acid, i.e., fruit acids. In this latter instance, i.e., (iii), significant benefits can be realized as fruit acids have been alleged to be capable of diminishing fine skin lines and pigmentation spots, as well as stimulating collagen which allows the skin to repair itself.

The common assignee's U.S. Pat. No. 5,948,855 contains an extensive list of some appropriate non-aqueous polar solvent soluble Vitamins and non-aqueous polar solvent soluble drugs which can be used, among which are Vitamin C, Vitamin B₁, Vitamin B₂, Vitamin B₆, Vitamin B₁₂, niacin, folic acid, biotin, and pantothenic acid. The non-aqueous polar solvent soluble vitamin can be used in the non-aqueous polar solvent-in-oil emulsions and multiple emulsions in amounts of from 0.01 to about 50 percent by weight.

The common assignee's U.S. Pat. No. 5,948,855 also contains an extensive list of some appropriate oil soluble active ingredients such as vitamins and drugs which can be used in the oil phase of the non-aqueous polar solvent-in-oil emulsions and multiple emulsions, among which are vitamins, including but not limited to, Vitamin A₁, RETINOL, C₂ -C₁₈ esters of RETINOL, Vitamin E, TOCOPHEROL, esters of Vitamin E, and mixtures thereof. RETINOL includes trans-RETINOL, 13-cis-RETINOL, 11-cis-RETINOL, 9-cis-RETINOL, and 3,4-didehydro-RETINOL. Other vitamins which are appropriate include RETINYL ACETATE, RETINYL PALMITATE, RETINYL PROPIONATE, .alpha.-TOCOPHEROL, TOCOPHERSOLAN, TOCOPHERYL ACETATE, TOCOPHERYL LINOLEATE, TOCOPHERYL NICOTINATE, and TOCOPHERYL SUCCINATE. The oil-soluble vitamin or drug can be used in the non-aqueous polar solvent-in-oil emulsions and multiple emulsions in amounts of from 0.01 to about 50 percent by weight.

In forming the primary emulsion PS₁ /O, it is preferred to use 0.1 to 99 percent by weight of the non-aqueous polar solvent phase PS₁, which amount includes the weight of the non-aqueous polar solvent and any non-aqueous polar solvent soluble active ingredient such as a vitamin(s) which may be carried therein. The oil phase O of the primary emulsion PS₁ /O is used in an amount of about 1 to 99.9 percent by weight, which amount includes the weight of the elastomeric silicone polyether, the oil, and the oil soluble vitamin(s) or oil soluble active ingredient included therein.

Preferably, the non-aqueous polar solvent phase including the weight of the non-aqueous polar solvent and any non-aqueous polar solvent soluble active ingredient comprises 20 to 95 percent by weight of primary emulsion PS₁ /O, while the oil phase including the weight of the elastomeric silicone polyether, the oil, and the oil soluble vitamin(s) or oil soluble active ingredient comprises 15 to 80 percent by weight of primary emulsion PS₁ /O.

Multiple emulsions PS₁ /O/W can then be prepared by simply mixing together about 0.1 to 70 percent by weight of the primary emulsion PS₁ /O, with about 30 to 99.9 percent by weight of the final continuous phase W, which latter amount includes the weight of any water soluble active ingredient(s) contained in final continuous phase W. Generally, any active ingredient referred to above as being an appropriate active ingredient for addition to the non-aqueous polar solvent phase is also an appropriate active ingredient for addition to the final continuous phase W. Multiple emulsions of the type PS₁ /O/PS₂ are prepared in a similar manner.

Claim 1 of 8 Claims

1. A composition comprising 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, the emulsifier being a crosslinked elastomeric silicone polyether which constitutes polymeric molecules crosslinked together to form a gel consisting of three-dimensional molecular polymeric networks containing crosslinking units between and among the polymeric molecules, the crosslinked elastomeric silicone polyether containing and being swollen with about 65 to about 98 percent by weight of the silicone oil.

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