Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Aqueous continuous liquid phase and discontinuous phase...
Reexamination Certificate
2001-07-25
2002-12-24
Dawson, Robert (Department: 1712)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Aqueous continuous liquid phase and discontinuous phase...
C556S444000, C556S445000, C524S588000, C524S837000
Reexamination Certificate
active
06498197
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an optically clear one-phase microemulsion which is transparent throughout a temperature range of from 0 to 70° C. comprising (i) at least one non-aqueous polar solvent, (ii) at least one non-polar solvent immiscible with (i), and (iii) at least one oxyalkylene-containing polydiorganosiloxane. The microemulsions of this invention are useful in personal care products.
Transparent mixtures of low molecular weight silicone oils using polymeric silicone surfactants have been described. For example, Gee in U.S. Pat. No. 4,620,878 discloses a method of preparing fine polyorganosiloxane emulsions with an average particle size of less than 0.3 micron and polyorganosiloxane microemulsions with an average particle size of less than 0.14 micron by preparing a translucent oil concentrate by mixing a polyorganosiloxane which contains polar groups, a surfactant which is insoluble in the polyorganosiloxane, and sufficient water to obtain a translucent mixture, the translucent oil concentrate is then rapidly dispersed in water to form the desired fine emulsion or microemulsion. Gee further discloses that if the translucent oil concentrate is not transparent a fine emulsion with an average particle size of less than 0.3 micron is obtained; whereas, if the oil concentrate is transparent, a microemulsion with an average particle size of less than 0.14 micron is obtained.
Gee et al. in U.S. Pat. No. 4,122,029 discloses stable emulsions of a polar liquid in a non-polar base liquid are prepared with the cooperating action of a mixture of a water-in-oil surfactant having an HLB value of from 2 to 10 and certain polydiorganosiloxane-polyoxyalkylene copolymers. Gee et al. Gee further discloses an antiperspirant composition comprising an aqueous solution of aluminum chlorohydrate as the polar liquid dispersed in cyclopolydimethylsiloxanes as the non-polar base liquid, using a mixture of nonylphenoxy polyethoxyethanol and a copolymer of a trimethylsiloxy-endblocked polydimethylsiloxane containing a minor amount of methylhydrogensiloxane units and an allyloxy-endblocked polyoxyethylenepolyoxypropylene copolymer.
Keil in U.S. Pat. No. 4,265,878 discloses antiperspirant stick compositions which comprise an aqueous solution of an astringent dispersed in a solid matrix comprising a volatile, water-insoluble liquid, a polydiorganosiloxane-polyoxyalkylene copolymer, a solid alkanoic acid, a waxy ester, and optionally containing a solid alkanol. Keil discloses that a preferred embodiment comprises an aqueous solution of aluminum chlorohydrate dispersed in a solid matrix comprising cyclopolydimethylsiloxanes as the volatile liquid. Keil further discloses that these compositions are stable to separation in the molten state and provide non-leaking sticks of controllable softness when solidified by cooling.
Keil in U.S. Pat. No. 4,268,499 discloses antiperspirant emulsion compositions which comprise an aqueous solution of an astringent agent; a volatile, water-insoluble liquid, a polydiorganosiloxane-polyoxyalkylene copolymer, an oil-in-water type surfactant, and a water-in-oil type surfactant. Keil discloses that a preferred embodiment comprises an emulsion of aqueous aluminum chlorohydrate in cyclopolydimethylsiloxanes as the volatile fluid and that these compositions have improved efficacy as measured by their drying times.
Microemulsions of low molecular weight silicone oils with hydrocarbon surfactants have been disclosed. For example, Hill et al. in U.S. Pat. No. 6,013,683 discloses a clear single phase composition containing 40-95% by weight of a cyclic or short chain linear methyl siloxane and water, and 5-60% by weight of a cationic surfactant and a nonionic surfactant. Hill et al. discloses that the cyclic or short chain linear methyl siloxane in the single phase composition has an average structure or droplet diameter of less than about 50 nanometer. Hill et al. further discloses that the single phase composition spontaneously provides optically clear one phase silicone microemulsions when combined with only hand agitation and that the clear single phase compositions are useful in personal care and textile applications.
Microemulsions of low molecular weight silicone oils using trisiloxane surfactants have been disclosed. For example, Hill in U.S. Pat. Nos. 5,705,562 and 5,707,613 discloses a method of spontaneously forming a highly stable clear microemulsion by combining (i) water, (ii) a volatile cyclic methyl siloxane or volatile linear methyl siloxane, and (iii) a silicone polyether surfactant. Hill discloses that the amounts of each component are such that the composition is in the form of a microemulsion and that the volatile methyl siloxane is present in the microemulsion in the form of particles having an average diameter of less than about 100 nanometers. Hill discloses that the microemulsion is useful in personal care products.
Microemulsions containing octanol, decanol, or dodecanol as the oil phase and oligomeric, grafted nonionic amphiphiles based on ethoxylated polydimethylsiloxanes have been disclosed, for example in Garti et al.,
Journal of Colloid and Interface Science
, Vol. 233, pp. 286-294 (2001). The surfactants of Garti et al. were two trisiloxanes and an oxyalkylene containing polydimethylsiloxane having the formula Me
3
SiO(Me
2
SiO)
4
(MeRSiO)
3
SiMe
3
where R is a group having the formula —(CH
2
)
3
(OCH
2
CH
2
)
10
OH. Garti et al. disclose that significant amounts of water could be solubilized only for the trisiloxane surfactants.
Iwanaga et al. in
Progress in Colloid
&
Polymer Science
, Vol. 110, pp. 225-229 (1998), disclose isothermal phase diagrams for two oxyalkylene-containing polydiorganosiloxanes with water and a cyclosiloxane having the structure —(MeSiO)
4
—showing L
&agr;
and H
2
liquid crystal phases, and a narrow region of oil-rich microemulsion along the oil-surfactant axis.
SUMMARY OF THE INVENTION
This invention relates to an optically clear one-phase microemulsion which is transparent throughout temperature range of from 0 to 70° C. comprising (i) at least one non-aqueous polar solvent, (ii) at least one non-polar solvent immiscible with (i), and (iii) at least one oxyalkylene-containing polydiorganosiloxane. The microemulsions of this invention are useful as delivery vehicles for personal care actives such as antiperspirant salts, sunscreens, alpha-hydroxy fatty acids, and Vitamin E.
It is an object of this invention to prepare optically clear one-phase microemulsions which are transparent at a temperature of 0 to 70° C.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to an optically clear one-phase microemulsion which is transparent at a temperature of 0 to 70° C. comprising (i) at least one non-aqueous polar solvent, (ii) at least one non-polar solvent immiscible with (i), and (iii) at least one oxyalkylene-containing polydiorganosiloxane having its formula selected from the group consisting of
R
3
SiO(RR
1
SiO)
y
SiR
3
,
R
3
SiO(R
2
SiO)
x
(RR
1
SiO)
y
SiR
3
,
R
1
R
2
SiO(RR
1
SiO)
z
SiR
2
R
1
,
R
1
R
2
SiO(R
2
SiO)
x
SiR
2
R
1
,
R
1
R
2
SiO(R
2
SiO)
x
(RR
1
SiO)
z
SiR
2
R
1
, and a cyclosiloxane copolymer having the formula —(Me
2
SiO)
m
(MeR
1
SiO)
n
—
wherein R denotes an alkyl group containing from 1 to 6 carbon atoms, R
1
denotes a group having its formula selected from the group consisting of
—(CH
2
)
a
(OCH
2
CH
2
)
b
OR
2
,
—(CH
2
)
a
(OCH
2
CH(CH
3
))
c
OR
2
,
—(CH
2
)
a
(OCH
2
CH(CH
2
CH
3
))
d
OR
2
,
—(CH
2
)
a
(OCH
2
CH
2
)
b
(OCH
2
CH(CH
3
))
c
OR
2
,
—(CH
2
)
a
(OCH
2
CH
2
)
b
(OCH
2
CH(CH
2
CH
3
))
d
OR
2
, and
—(CH
2
)
a
(OCH
2
CH
2
)
b
(OCH
2
CH(CH
3
))
c
(OCH
2
CH(CH
2
CH
3
))
d
OR
2
wherein a has a value of 3 to 11, b has a value of 1 to 20, c has a value of 1 to 10, d has a value of 1 to 4, and R
2
is selected from the group consisting of hydrogen, an alkyl group, and an acyl group, x has a value of 1 to 400, y has a value of 1 to 40, z has a value of 1 to 40, m has a value of 1 to 6, n has a value of 1 to 6, and the value of m+n is from 3 to 6.
Microemuls
Bialek Aneta Ilona
Hill Randal Myron
Kadlec Donald Anthony
Van Dort Heidi Marie
Dawson Robert
Dow Corning Corporation
Peng Kuo-Liang
Troy Timothy J.
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