Stable water in oil emulsions

There is described water-in-oil emulsions containing polysiloxane surface active agents which can be formulated into lotions for use in sunscreens and skin care products.

FIELD OF THE INVENTION 
The present invention relates to water-in-oil emulsions containing surface 
active agents of polysiloxane. More particularly, the present invention 
relates to sunscreens and skin care lotions containing water-in-oil 
emulsions containing polysiloxane surface active agents having radial 
organic polyether groups. 
BACKGROUND OF THE INVENTION 
The use of polysiloxane surface active agents containing radial organic 
polyether groups to stabilize silicone emulsions is well known. U.S. Pat. 
No. 4,265,878 uses a polysiloxane surface active agent to stabilize 
antiperspirant stick compositions. U.S. Pat. No. 4,218,250 uses such a 
polysiloxane surface active agent to stabilize polish formulations. U.S. 
Pat. No. 4,268,499 uses these surface active agents to stabilize 
antiperspirant emulsion compositions. Further, U.S. Pat. No. 4,311,695 
uses such surface active agents in personal care creams and the like. 
Also, mention is made of U.S. Pat. No. 4,980,156, which describes improved 
antiperspirant compositions comprising an emulsion of an aqueous 
astringent in a volatile silicone fluid. Further, special mention is made 
of U.S. Pat. No. 4,988,506, which describes polysiloxane surface active 
agents having high molecular weight. 
The subject polysiloxane surface active agents are generically known and 
are sometimes referred to as siloxaneoxyalkylene copolymers. However, 
their use to date has been directed to stabilizing silicone emulsions in 
skin care creams and antiperspirant sticks. However, their use in forming 
stable lotions has not been completely satisfactory, due to emulsion 
instability, because the variables affecting their function are not well 
understood. As will be shown in the appended examples, if, instead of 
antiperspirant sticks, lotions are made using a lipophilic organic 
surfactant together with a lipophilic polysiloxane copolymer (e.g., U.S. 
Pat. No. 4,988,504) they show low emulsion stability and relatively low 
freeze/thaw resistance. Surprisingly, however, it has now been found that 
if a hydrophilic surfactant is used together with certain lipophilic 
polysiloxane copolymers, in lotions, long term stable emulsions with 
excellent resistance to freeze/thaw cycling are obtained. 
It is the object of the present invention to produce novel skin care and 
sunscreen lotions having superior emulsion stability containing surface 
active agents comprising an organic hydrophobic surfactant and a siloxane 
surfactant containing radial organic polyether groups. 
It is another object of the present invention to provide a water-in-oil 
silicone emulsion having excellent freeze-thaw stability. 
SUMMARY OF THE INVENTION 
Briefly, there is provided by the present invention an improved 
water-in-oil emulsion sunscreen or skin care lotion comprising (a) from 
89.5 to about 40 parts by weight of an aqueous solution as a discontinuous 
phase; (b) from about 10 to about 45 parts by weight of a volatile liquid 
having a normal boiling point of less than 250.degree. C. as a continuous 
phase, the volatile liquid being selected from the group of organosiloxane 
fluids having the average unit formula (CH.sub.3 ).sub.a SiO.sub.(4-a)/2, 
wherein "a" has an average value of from 2 to 3, inclusive; (c) from about 
0.1 to about 3 parts by weight of an organic oil-in-water type surfactant 
having an HLB value of from 8 to 18, inclusive; and (d) from about 0.4 to 
about 20 parts by weight of a polyorganosiloxane polyoxyalkylene copolymer 
surface active agent of the formula MD.sub.x D'.sub.y M, wherein D is 
R.sub.2 SiO.sub.2/2 where R is hydrogen or a substituted or unsubstituted 
hydrocarbon radical of from 1 to about 12 carbon atoms, D' is 
RR'SiO.sub.2/2 where R is as defined above and R' is a polyalkylene ether 
of the formula --R.sup.3.sub.a --(OR.sup.2 ).sub.n --OR.sup.4 where 
R.sup.2 is a --CH.sub.2 --CH.sub.2 -- group, R.sup.3 is a substituted or 
unsubstituted alkylene group of 1 to 20 carbon atoms, R.sup.4 is the same 
as R, n has a value of from 5 to about 20, and a is 0 or 1; M represents 
trimethylsiloxy endcapping units, x is from about 335 to about 475, and y 
is from about 4 to about 23; with the proviso that the molecular weight of 
polysiloxane units D is from about 25,000 to about 35,000 and the weight 
ratio of D to D' is from greater than 60/40 to 90/10. 
The emulsions of the present invention are in the form of a lotion and 
preferably comprise an additive (e) selected from the group consisting of 
an antiperspirant, a humectant, an insect repellent, an odorant, a 
deodorant, an emollient, an antiseptic, a sunscreen agent, a cleansing 
agent, a suitable pharmaceutical, a pigment, a biocide, and mixtures of 
any of the foregoing. Most preferred are sunscreen agents such as titanium 
dioxide, UVA and UVB filters which are known to those skilled in the art 
and are available commercially. 
Typically, the UV filters are selected from para amino benzoic acid (PABA) 
and para amino benzoates, salicylates, cinnamates, benzophenones, 
anthranilates, dibenzoyl methanes, camphor derivatives and mixtures 
thereof. 
Suitable R groups include hydrogen, methyl, ethyl, vinyl, phenyl, 
trifluoropropyl, etc. Preferably, at least 80% by number of all R groups 
are methyl. 
R.sup.2 may be --CH.sub.2 --CH.sub.2 --, --CH.sub.2 CH(CH.sub.3)--, 
--CH.sub.2 C(CH.sub.3).sub.2 --, --CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 --, 
etc. However, it is preferred that at least 50% by number of R.sup.2 units 
are --CH.sub.2 CH.sub.2 --. 
It is preferred herein that the number of repeating units of R', i.e. the 
value of n, be between about 5 and 20. Thus, in the case of ethylene oxide 
as the repeating unit, the molecular weight of R' should be less than 
about 900. The preferred value of n is from 10 to 15, which likewise for 
ethylene oxide provides a molecular weight of R' of no more than about 
700. 
R.sup.3 is the group which bonds the polyoxyalkylene segment to the 
polysiloxane. Preferably, this group is derived from alpha-beta 
unsaturated carboxylic acids or alcohols. Thus, R.sup.3 may be --CH.sub.2 
CH.sub.2 CH.sub.2 --, --CH.sub.2 CH.sub.2 --, --CH.sub.2 CH.sub.2 CH.sub.2 
CH.sub.2 --, --(CH.sub.2).sub.10 (C.dbd.O)-- etc. Preferably, R.sup.3 is 
--CH.sub.2 CH.sub.2 CH.sub.2 --. Otherwise, "a" could be 0 and the 
segments joined by --O--, which is the product of a condensation reaction 
between a condensable substituent on the polysiloxane and a condensable 
end group on polyalkylene oxide. 
R.sup.4 is the terminal group of the polyalkylene ether. The type of 
R.sup.4 is not critical and may be selected from hydrogen, methyl, ethyl, 
propyl, butyl, phenyl, alkenyl, acetyl, etc. Preferably, R.sup.4 is 
hydrogen. 
The polysiloxane absent R' should have a molecular weight between about 
15,000 about 50,000 and preferably between 25,000 and 35,000. 
DETAILED DESCRIPTION OF THE INVENTION 
Component (a) of the present invention is the discontinuous phase. The 
discontinuous phase preferably comprises water. 
However, it is also contemplated that the discontinuous phase can comprise 
liquid media other than water. Suitable liquid media are organic compounds 
such as alcohols, including methanol, ethanol, phenol, ethylene glycol, 
propylene glycol, glycerine, their partial ethers and partial esters; 
nitrogen compounds including amides such as formamide, acetamide, 
N,N-dimethyl formamide and urea; nitriles such as acetonitrile, and amines 
and their salts; acids such as formic acid, acetic acid, benzoic acid, 
stearic acid and ethylene diaminetetraacetic acid; and ethers such as 
furan, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, propylene 
glycol dimethyl ether and their polymeric forms such as triethylene glycol 
diethyl ether. Mixtures of any of the foregoing and mixtures of any of 
them with water are contemplated by the present invention. 
Emulsion compositions of this invention wherein the aqueous phase comprises 
water and/or ethanol are particularly useful. In common with oil-in-water 
emulsions, water-in-oil emulsions are desirable from an economic, safety 
and environmental viewpoint as a means of preparing, storing, shipping and 
using efficacious components. In addition, emulsion compositions of 
aqueous or ethanol solutions have value as personal care compositions. 
The base oil or volatile liquid continuous phase (b) is generally a fluid 
selected from the organosiloxane fluids having a normal, i.e. atmospheric 
pressure, boiling point of less than 2500.degree. C. The volatile 
organosiloxane fluids have the average unit formula: 
EQU R.sub.a SiO.sub.(4-a/2) 
wherein R is hydrogen or a substituted or unsubstituted hydrocarbon radical 
of from 1 to about 12 carbon atoms and "a" has an average value of from 2 
to 3. Preferably, R is methyl and the organosiloxane is selected from the 
group consisting of (CH.sub.3 ).sub.3 SiO.sub.1/2, (CH.sub.3).sub.2 
SiO.sub.2/2, CH.sub.3 SiO.sub.3/2 and SiO.sub.4/2 units. Preferably, the 
volatile methylsiloxane fluid consists essentially of dimethylsiloxane 
units, and optionally, trimethylsiloxane units. Of particular value as 
volatile liquid (b) are the cyclic siloxanes of the general formula 
((CH.sub.3).sub.2 SiO).sub.b and the linear siloxanes of the general 
formula (CH.sub.3).sub.3 SiO((CH.sub.3).sub.2 SiO).sub.c 
Si(CH.sub.3).sub.3, and their mixtures, wherein b is an integer of from 3 
to 6 and c is an integer of from 0 to 4. A highly preferred methylsiloxane 
fluid is a mixture of the cyclic siloxanes wherein a major portion is 
tetramer, i.e. b=4. 
Component (c) are organic oil-in-water type surfactants. These can be any 
cationic, anionic or nonionic organic surfactant suitable for preparing 
emulsions of the oil-in-water type and having a hydrophilic-lipophilic 
balance, HLB, value of from 8 to 18, inclusive. Examples of oil-in-water 
type surfactants include polyethoxylated quaternary ammonium salts and 
polyoxyethylene fatty amines as cationic surfactants, and 
polyethylene-glycol alkylethers, polyethylene-glycol alkylarylethers, 
polyethoxylated sorbitan monolaurate, polyethoxylated sorbitan monooleate, 
polyoxyethylene lanolin derivatives, and polyethoxylated fatty alcohols as 
nonionic surfactants. Mixtures of cationic and/or nonionic oil-in-water 
surfactants are also suitable. Other examples of suitable organic 
surfactants having an HLB value of from 8 to 18 may be found by consulting 
standard publications such as McCutcheon's "Detergents and Emulsifiers," 
1975 North America Edition, MC Publishing Co., Glen Rock, N.J., 1975. 
Component (d) comprises polyorganosiloxane polyoxyalkylene copolymer 
surface active agents. The copolymer surface active agents useful in the 
practice of the present invention are of the general formula: 
EQU MD.sub.x D'.sub.y M 
wherein M, D, D', x and y are as previously defined. 
The polysiloxane surface active agent may be prepared by well known 
methods. The preferred method is to introduce an alpha-beta unsaturated 
alcohol or carboxylic acid into the polymerization of alkylene glycols to 
produce a terminally unsaturated polyalkylene oxide. These terminally 
unsaturated polyalkylene glycols are subsequently added to silicon bonded 
hydrogens on suitable polysiloxanes. The addition reaction proceeds best 
in the presence of an active metal catalyst such as platinum. 
The manufacture of the polysiloxane surface active agents is well known and 
understood by those skilled in the art. Methods of preparation are taught 
in U.S. Pat. Nos. 4,265,878; Re 25,727; 3,174,987; 4,122,029, and 
3,172,899, all of which are hereby incorporated by reference. 
The compositions of the present invention are generally prepared by first 
forming the aqueous phase A by mixing together components (a) and (c). 
Then the oily phase B is prepared by mixing together components (b) and 
(d). The additive (e) is then added to either phase A or B, depending upon 
the type of additive as known to those skilled in the art. The two phases 
are then mixed, preferably with high sheer agitation, to form an emulsion. 
Optionally, the emulsions may be further homogenized. 
The lotions of the present invention can then be used in a wide variety of 
end products depending upon the additives employed. Typically, the lotions 
may be formulated into skin care creams, suntan lotions, make-up, facial 
scrubs and cleansing creams. 
Preferred formulations are sunscreen lotions and personal care lotions. 
These may be formulated using the water-in-oil emulsions of the present 
invention. Such compositions contain (A) from about 89.5 to about 40 parts 
by weight water (B) from about 10 to about 45 parts by weight 
organosiloxane fluid, (C) from about 0.1 to about 3 parts by weight of an 
organic oil-in-water surfactant having an HLB value of 8 to 18, (D) from 
about 0.4 to about 20 parts by weight of polysiloxane surface active agent 
and (E) an effective amount of sunscreen or other desired skin care agent.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The following examples illustrate the present invention. They are not to be 
construed to limit the claims in any manner whatsoever. 
EXAMPLES 1-3 
A series of general skin care water-in-oil formulations were prepared using 
SF1228 combined with "POLYSORBATE 80" as the emulsifier system. 
The emulsions are prepared according to the following: Part A, the oil 
phase, is prepared by mixing together 10 parts by weight SF-1228, a 
polyorganosiloxane polyoxyalkylene copolymer emulsifier, 6 parts by weight 
of SF-1202, a cyclomethylsiloxane fluid, and 4 parts by weight of 
isopropyl myristate, a liquid ester emollient. Part B, the aqueous phase, 
is prepared by mixing together 0.2 parts by weight of polysorbate 80, an 
organic oil-in-water surfactant, 3.0 parts by weight of propylene glycol, 
1 part by weight of sodium chloride and 75.8 parts by weight of water. 
Part B is then added to Part A with high shear agitation in a vessel, at 
room temperature. The emulsion formed is then milled in a Gifford-Wood 
homogenizer to increase stability. 
Examples 2 and 3 are prepared according to the above procedure, varying the 
type of skin care additives. The compositional data is set forth below in 
Table 1. 
TABLE 1 
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SKIN CARE FORMULATIONS 
Examples 1 2 3 
______________________________________ 
Part A, pbw 
SF-1228.sup.a 10.0 10.0 10.0 
SF-1202.sup.b 6.0 5.0 7.0 
Isopropl Myristate 
4.0 4.0 -- 
Lanolin.sup.c -- 1.5 1.0 
SS-4267.sup.d -- -- 3.0 
Part B, pbw 
Polysorbate 80.sup.e 
0.2 0.2 0.2 
Glycerine -- 3.0 3.0 
Propylene glycol 
3.0 -- -- 
Sodium Chloride 
1.0 1.0 1.0 
Water 75.8 75.3 74.8 
______________________________________ 
.sup.a = Polyorganosiloxane Polyoxyalkylene copolymer, General Electric 
Company 
.sup.b = Cyclomethylsiloxane Fluid, General Electric Company 
.sup.c = Fluilan brand of lanolin made by Croda, Inc. 
.sup.d = Methylsiloxane Fluid and Methylsiloxane resin 
.sup.e = Ethoxylated sorbitan oleate 
All formulations passed 60 days at 40.degree. C. stability testing and 4 
freeze/thaw cycles at -10.degree. C. for 8 hours and 25.degree. C. for 16 
hours. 
EXAMPLES 4-5 
The procedure of Example 1 is followed, except that various sunscreen 
additives are employed in the oil phase. For comparative purposes, two 
formulations similar to Example 4 are also prepared and tested back to 
back. In Example A, no polysorbate 80 is added; ad in Example B, 
polysorbate oleate (HLB 4.3) is employed in place of polysorbate 80 (HLB 
15.0). The composition data is set forth below in Table 2. 
TABLE 2 
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SUN PROTECTION FORMULATIONS 
Example 4A* 4B* 4 5 
______________________________________ 
Part A, pbw 
SF-1228.sup.a 10.0 10.0 10.0 100 
SF-1202.sup.b 12.0 12.0 12.0 100 
Octyl salicylate -- -- -- 30 
Lonzest 143-S.sup.c 
-- -- -- 30 
Lanolin.sup.d 0.5 0.5 0.5 -- 
Neoheliopan AV.sup.e 
5.0 5.0 5.0 60 
Micronized Titanium Dioxide 
3.0 3.0 3.0 30 
SS-4267.sup.f 3.0 3.0 3.0 -- 
Mineral Oil (70 SUS.sup.g) 
1.0 1.0 1.0 -- 
Sorbitan Oleate -- 0.2 -- -- 
Part B, pbw 
Polysorbate 80 -- -- 0.2 02 
Glycerine 3.0 3.0 3.0 30 
Sodium Chloride 1.0 1.0 1.0 10 
Water 61.5 61.3 61.3 608 
______________________________________ 
* = Comparative Example 
.sup.a = Polyorganosiloxane polyoxyalkylene copolymer, General Electric 
Company 
.sup.b = Cyclomethylsiloxane fluid, General Electric Company 
.sup.c = Lonza, Inc. brand of myristal proprionate 
.sup.d = Croda, Inc. brand of lanolin 
.sup.e = Haarmann and Reiner Corp. brand of octylmethoxycinnamate 
.sup.f = Methylsiloxane Fluid and Methyl Siloxane Resin 
.sup.g = SUS is Saybolt Universal Seconds visocity measurement 
The formulations within the scope of the appended claims (Examples 4 and 5) 
showed excellent stability (no separation) during a stability test at 
40.degree. C. for 60 days and also in testing at 4 freeze/thaw cycles. The 
formulations without the polysorbate 80 (Examples 4A* and 4B*) and 
unexpectedly lower viscosity than that of Example 4. Further, after 24 
hours at 40.degree. C., separation was noticeable in both Examples 4A* and 
4B*, with Example 4B* being slightly worse than 4A*. 
The above-mentioned patents are hereby incorporated by reference. 
Many variations of the present invention will suggest themselves to those 
skilled in the art in light of the above-detailed description. All such 
obvious modifications are within the full intended scope of the appended 
claims.