U.S. patent application number 10/819741 was filed with the patent office on 2004-10-07 for water-thin emulsions with low emulsifier levels.
Invention is credited to Bevacqua, Andrew J., Cioca, Gheorghe, George, Liliana, Matathia, Michelle, Tadlock, Charles Craig.
Application Number | 20040198843 10/819741 |
Document ID | / |
Family ID | 24322366 |
Filed Date | 2004-10-07 |
United States Patent
Application |
20040198843 |
Kind Code |
A1 |
George, Liliana ; et
al. |
October 7, 2004 |
Water-thin emulsions with low emulsifier levels
Abstract
The invention relates to a water-thin emulsion comprising a
non-phospholipid, non-ethoxylated pseudoemulsifier system, the
system having a chemical composition with at least one hydrophobic
moiety and at least one polar moiety, the size, shape and/or planar
arrangement of the hydrophobic and polar moieties being
asymmetrical with respect to each other. The emulsion of the
invention is prepared by high-pressure homogenization of a crude
oil and water emulsion containing the pseudoemulsifier. The
emulsions require little or no traditional emulsifier to maintain
stability, and are particularly useful in the preparation of
multiple emulsions.
Inventors: |
George, Liliana;
(Centerport, NY) ; Bevacqua, Andrew J.; (East
Setauket, NY) ; Cioca, Gheorghe; (Lake Grove, NY)
; Matathia, Michelle; (Plainview, NY) ; Tadlock,
Charles Craig; (Islip Terrace, NY) |
Correspondence
Address: |
THE ESTEE LAUDER COS, INC
ATTN: KAREN A. LOWNEY
125 PINELAWN ROAD
MELVILLE
NY
11747
US
|
Family ID: |
24322366 |
Appl. No.: |
10/819741 |
Filed: |
April 7, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10819741 |
Apr 7, 2004 |
|
|
|
09580743 |
May 26, 2000 |
|
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Current U.S.
Class: |
516/53 |
Current CPC
Class: |
Y10S 526/932 20130101;
Y10S 514/941 20130101; Y10S 514/943 20130101; A61P 29/00 20180101;
A61Q 5/00 20130101; Y10S 514/938 20130101; A61P 17/00 20180101;
A61K 8/066 20130101; Y10S 516/902 20130101; Y10S 435/839 20130101;
A61Q 19/00 20130101 |
Class at
Publication: |
516/053 |
International
Class: |
B01F 017/00 |
Claims
What is claimed is:
1. A water-thin emulsion comprising a non-phospholipid,
non-ethoxylated pseudoemulsifier system, the system having a
chemical composition with at least one hydrophobic moiety and at
least one polar moiety, the size, shape and/or planar arrangement
of the hydrophobic and polar moieties being asymmetrical with
respect to each other.
2. The emulsion of claim 1 in which the system is a single compound
having at least two hydrophobic moieties, at least two polar
moieties, or at least two of both hydrophobic and polar
moieties.
3. The emulsion of claim 1 in which the system is a mixture of
compounds comprising at least two hydrophobic moieties, at least
two polar moieties, or at least two of both hydrophobic and polar
moieties.
4. The emulsion of claim 1 which is substantially free of
phospholipid and ethoxylated emulsifiers.
5. The emulsion of claim 1 which contains no more than 2% by weight
of the pseudoemulsifier.
6. The emulsion of claim 1 which contains no more than 1% of the
pseudoemulsifier.
7. The emulsion of claim 1 in which the pseudoemulsifier is a
2-amidocarbonyl-benzoic acid compound having the formula (I)
wherein R.sub.1 and R.sub.2 are independently H or
(CH.sub.2).sub.nCH.sub.3, wherein n=8-22, provided that at least
one of R.sub.1 and R.sub.2 is H, wherein M.sup.+ is a cation
selected from the group consisting of H, Na, K, NH.sub.4 and
derivatives thereof (for example, basic amino acids), Ba, Ca, Mg,
Al, Ti, and Zr, and y is an integer of a value satisfying the
valency of M.sup.+.
8. The emulsion of claim 7 in which the pseudoemulsifier is a
monovalent salt of stearyl amidobenzoic acid.
9. The emulsion of claim 1 in which the pseudoemulsifier is
surfactin.
10. The emulsion of claim 1 in which the system also comprises a
polymer.
11. The emulsion of claim 10 in which the polymer comprises
dispersed hydrophilic moieties.
12. The emulsion of claim 11 in which the polymer is selected from
the group consisting of disaccharides, polysaccharides, or a
predominantly hydrophilic peptide or protein.
13. The emulsion of claim 3 in which the system comprises at least
one compound selected from the group consisting of glycerol esters,
sucrose esters and glucose esters.
14. The emulsion of claim 13 in which the system comprises both a
glycerol ester and a sucrose or glucose ester.
15. The emulsion of claim 14 in which the system also comprises a
polymer.
16. The emulsion of claim 15 in which the polymer is selected from
the group consisting of disaccharides, polysaccharides, and
predominantly hydrophilic proteins or peptides.
17. The emulsion of claim 3 in which the system comprises xanthan,
polyglucomannan, a high HLB emulsifier, and a low HLB
emulsifier.
18. The emulsion of claim 13 in which the system comprises xanthan,
polyglucomannan, a high HLB emulsifier, and a low HLB
emulsifier.
19. A water-thin oil-in-water emulsion comprising a
non-phospholipid, non-ethoxylated pseudoemulsifier system, the
system having a chemical composition with at least two hydrophobic
moieties, at least two polar moieties, or at least two of both
hydrophobic and polar moieties, the size, shape and/or planar
arrangement of the hydrophobic and polar moieties being
asymmetrical with respect to each other, each polar moiety being of
a different size or shape than the other polar moiety if present,
and each hydrophobic moiety being of different size or shape than
the other if present.
20. The emulsion of claim 19 in which the hydrophobic moieties are
of different chain lengths.
21. The emulsion of claim 19 in which at least one of the moieties
has a closed ring structure.
22. The emulsion of claim 19 in which at least one of the moieties
is a long straight-chain moiety.
23. The emulsion of claim 19 in which at least one of the moieties
has a closed ring structure, and one of the moieties is a long,
straight chain moiety.
24. The emulsion of claim 23 in which the system comprises a
hydrophobic closed ring structure, and a long chain hydrophobe,
separated from each other by a hydrophilic moiety.
25. The emulsion of claim 24 in which the hydrophilic moiety is
selected from the group consisting of hydroxyl, amide, ester, or
carboxyl moieties, hydrocarbons chains substituted with hydroxyl,
amide, ester, or carboxyl moieties, and combinations thereof.
26. The emulsion of claim 23 in which the system comprises a
hydrophilic closed ring structure, at least one carboxyl moiety,
and a long chain fatty acid moiety.
27. The emulsion of claim 19 in which the emulsifier system
comprises more than one compound.
28. The emulsion of claim 27 in which at least one of the compounds
comprises a long, straight-chain hydrocarbon moiety.
29. The emulsion of claim 28 in which at least one of the compounds
comprises a hydrophilic moiety selected from the group consisting
of hydroxyl, amide, ester, or carboxyl moieties, hydrocarbons
chains substituted with hydroxyl, amide, ester, or carboxyl
moieties, and combinations thereof.
30. The emulsion of claim 29 in which the system further comprises
a polymer selected from the group consisting of disaccharides,
polysaccharides, and predominantly hydrophilic proteins or
peptides.
31. A water-thin oil-in-water emulsion prepared by processing the
combined oil and water phases comprising a non-phospholipid,
non-ethoxylated pseudoemulsifier system, the system having a
chemical composition with at least one hydrophobic moiety and at
least one polar moiety, the size, shape and/or planar arrangement
of the hydrophobic and polar moieties being asymmetrical with
respect to each other, through a high pressure homogenizer at a
pressure of at least about 15,000 psi.
32. The emulsion of claim 31 in which the system is a single
compound having at least two hydrophobic moieties, at least two
polar moieties, or at least two of both hydrophobic and polar
moieties.
33. The emulsion of claim 31 in which the system is a mixture of
compounds comprising at least two hydrophobic moieties, at least
two polar moieties, or at least two of both hydrophobic and polar
moieties.
34. A multiple emulsion comprising the emulsion of claim 1.
35. A multiple emulsion incorporating the emulsion of claim 6.
36. A multiple emulsion incorporating the emulsion of claim 19.
37. A multiple emulsion incorporating the emulsion of claim 27.
38. The emulsion of claim 33 that comprises no greater than 1% of
traditional emulsifier.
39. The emulsion of claim 35 that comprises no greater than 1% of
traditional emulsifier.
40. The emulsion of claim 36 that comprises no greater than 1% of
traditional emulsifier.
41. The emulsion of claim 37 that comprises no greater than 1% of
traditional emulsifier.
42. A multiple emulsion prepared by combining a water-in-oil
emulsion with the emulsion of claim 1, and mixing to substantial
homogeneity.
43. A method of making a water-thin, oil-in-water emulsion
comprising processing the combined oil and water phases comprising
a non-phospholipid, non-ethoxylated pseudoemulsifier system, the
system having a chemical composition with at least one hydrophobic
moiety and at least one polar moiety, the size, shape and/or planar
arrangement of the hydrophobic and polar moieties being
asymmetrical with respect to each other, through a high pressure
homogenizer at a pressure of at least about 15,000 psi.
Description
[0001] This application is a continuation and claims benefit of
U.S. Ser. No. 09/580,743, filed 26 May 2000 and currently
allowed.
FIELD OF THE INVENTION
[0002] The invention relates to cosmetic and pharmaceutical
formulations. More specifically, the invention relates to cosmetic
and pharmaceutical formulations containing low levels of
emulsifiers.
BACKGROUND OF THE INVENTION
[0003] One of the most common vehicles for cosmetic and
pharmaceutical products is the emulsion. Because they are formed by
the dispersion of an oil in water, or water in an oil, they provide
great versatility in the delivery of different types of active
ingredients. A single oil and water formulation can be used to
deliver both oil soluble and water soluble active components,
thereby giving the formulation a range of potential activity that
cannot be matched by a single phase system.
[0004] There are of course limitations to an emulsion vehicle, by
virtue of its combination of two inherently incompatible phases.
First, an emulsion ordinarily will have a certain amount of innate
viscosity; while not necessarily a problem per se, the thickness of
the emulsion can prevent its use in certain types of products or
packaging that require a less viscous texture. In addition, in
order to maintain a stable dispersion, it is ordinarily necessary
to add to the formulations substantial amounts of emulsion
stabilizers and/or emulsifiers. The necessity of addition of these
materials not only adds cost to the final product, but also has an
effect on the quality of the final product, by affecting the way
the emulsion breaks, as well as how it feels on the skin. Added
stabilizers can add to the viscosity of the emulsion, and certain
emulsifiers can be irritating to the skin of some users.
[0005] There have been attempts to overcome some of these
difficulties. One common approach is the use of high pressure
homogenization techniques, in which a crude emulsion is passed
through a high pressure homogenizer to yield a relatively thin
emulsion. This technique can contribute to a reduction in the
viscosity of the emulsion, and such emulsions have even been stated
as being made with relatively low levels of emulsifiers. However,
the emulsifiers used in these situations are either of the type
that are known to cause irritation, i.e., non-ionic ethoxylated
emulsifiers, or amphoteric, lecithin-type (phospholipid)
emulsifiers, which, being naturally-occurring products, are rather
costly to use. In some cases, these emulsions will still require an
addition of emulsion stabilizers to maintain stability over long
periods of time. There thus continues to be a need for a water-thin
emulsion which employs minimal levels of a non-irritating
emulsifier.
SUMMARY OF THE INVENTION
[0006] The present invention relates to water-thin emulsions
prepared by high pressure homogenization, in the presence of a
non-phospholipid, non-ethoxylated "pseudoemulsifier" having a
chemical composition comprising at least one hydrophobic moiety,
and at least one polar moiety, the size and/or the planar at least
two of one or of both of the types of moieties. Although not
ordinarily effective for use alone in maintaining stability of
emulsions, the pseudoemulsifiers have been shown to be highly
effective in maintaining the stability of these water-thin
emulsion, even at very low levels, i.e., less than 1%, and in
addition are very mild and non-irritating to the skin. The
water-thin emulsions find a variety of uses as a base for both
cosmetic and pharmaceutical products. The invention also provides a
method for producing a water-thin emulsion, comprising mixing oil
and water phases in the presence of the pseudoemulsifier, and
subjecting the mixture to high pressure homogenization.
BRIEF DESCRIPTION OF THE FIGURES
[0007] FIGS. 1a and 1b are schematic illustrations of possible
different arrangements of hydrophobic and hydrophilic moieties in
the pseudoemulsifiers of the present invention.
[0008] FIG. 2 is a schematic illustration of a surfactin molecule.
"AA" represents an amino acid.
DETAILED DESCRIPTION OF THE INVENTION
[0009] The emulsions of the invention have substantially no
viscosity, i.e., they exhibit approximately the consistency of
water. The consistency of the emulsions is primarily due to their
processing under high pressure homogenization. In brief, the
emulsion is prepared, in accordance with art-recognized techniques,
by forming a crude mixture of the oil and water phases, in the
presence of the appropriate emulsifier(as defined in more detail
below), and passing it through a high pressure homogenizer for a
time sufficient to achieve a stable emulsion. The pressure
sufficient to achieve the stable emulsion ranges from about 15,000
to about 45,000 psi, or about 1000-3100 bar, preferably about
1300-3000 bar, utilizing one or more passes. Suitable homogenizers
for this purpose are commercially available; these include a
microfluidizer, Dee Bee 2000 (BEE International) and Cavitator(Five
Star International). The preferred emulsion is an oil-in-water
emulsion.
[0010] While the homogenization process is important in obtaining
the appropriate consistency of the emulsion, this aspect alone is
not unique. The water-thin emulsions of the present invention
utilize a type of non-ethoxylated, non-phospholipid
"pseudoemulsifier", i.e., a compound or compounds that are not
traditionally considered or used as emulsifiers, and/or which, when
used alone in a traditional emulsion, are ordinarily not capable of
stabilizing the emulsion at the very low levels used in the present
invention. The type of emulsifier used is a non-ethoxylated,
non-phospholipid having a chemical composition containing both
hydrophobic moieties and polar (or hydrophilic) moieties, but with
an asymmetrical molecular arrangement of the moieties. By
"asymmetrical" is meant that the different moieties are of
different sizes (e.g., short chain vs. long chain) and/or shapes
(e.g., straight chain vs. cyclic), and/or are arranged in different
three-dimensional planes within the composition. Preferably, the
pseudoemulsifier is a single compound in which there are at least
two of either the hydrophilic or hydrophobic moieties. The moieties
of a given type may be the same or different, but are preferably
different from each other, e.g., a compound will preferably have at
least two different hydrophilic moieties, and/or at least two
different hydrophobic moieties. Hydrophobic moieties can be any
primarily hydrocarbon moiety, including, but not limited to, C1-40
linear or branched, substituted or unsubstituted alkyl, cycloalkyl,
alkylene, alkaryl, or aryl groups. The polar or hydrophilic
moieties are, for example, hydroxyl, carboxyl, ester, or amide
groups, or hydrocarbon moieties that are highly substituted with
such polar groups, or combinations thereof. Preferably, the
moieties of the same type in a compound are also unequal in size or
shape, for example, the hydrophobic moieties can be an alkyl and an
aryl group, or two alkyls of different chain length. It is most
preferable that the pseudoemulsifier have at least one closed,
rigid structure, which can be either hydrophilic or hydrophobic in
nature, for example, an aliphatic ring with ether, ester or amide
linkages, or an aromatic ring, the rigid structure being anchored
by at least one long-chain, i.e., C8-22, straight or branched
hydrophobe or hydrophile, and one or two short chain hydrophiles or
hydrophobes. Particularly preferred long-chain moieties are C8-22
fatty acid moieties, such as stearate or palmitate. Schematic
illustrations of some possible different arrangements of groups in
a single compound are shown in FIG. 1. The preferred arrangements
provide for a broadly dispersed hydrophilic domain separating the
components of the hydrophobic domain. ordinarily, such molecules
will not be readily water-soluble or oil-soluble at room
temperature, but will be readily dispersible in either at higher
temperatures.
[0011] In the case in which the emulsifier does not have a rigid
structure per se, it is possible to confer the necessary rigidity
by combining the emulsifier with a polymer having dispersed
hydrophilic groups along the molecule, to form an emulsifier
system. Polymers of this type will hydrogen-bond within the system,
thereby creating the structure needed to mimic the desirable
structure described above. Examples of useful polymers of this type
include sugars, such as disaccharides, e.g., sucrose, lactose, or
maltose, and polysaccharides, e.g., cellulose, pectin, xanthan gum,
or amylose; or a predominantly hydrophilic peptide or protein,
i.e., ones having a preponderance of hydrophilic or polar amino
acid residues.
[0012] Although it is preferred that the emulsifier components be
combined in a single molecule, it is also possible to create a
mixture of compounds, having a similar balance of polar and
hydrophobic moieties and "asymmetry" as described above, i.e.,
comprising more than one compound, the compounds used containing a
mixture of hydrophobic components and polar or hydrophilic
components as described above for the moieties of a single
compound, and which mixture will accomplish the same result as the
use of the single compound. The combination of compounds should
have an overall average HLB value of between 6 and 8. In one
embodiment, the components used can incorporate one hydrophilic and
one hydrophobic moiety in a single molecule, for example, a
glycerol ester, such as polyglyeryl-2-isostearate or a sucrose or
glucose ester, such as sucrose stearate or sucrose cocoate, in
combination with one or more compounds which have hydrophilic or
hydrophobic moieties. As with the single compound embodiment, it is
preferred that there be at least two hydrophobic moieties or at
least two hydrophilic moieties present in the components employed.
In the case in which separate compounds are used to contribute the
individual hydrophilic and hydrophobic moieties, however, the
requisite structure or rigidity will not be present without the
addition of a polymer to tie the components together. Therefore,
with separate compounds being used, the addition of a polymer with
disperse hydrophilic groups is important; the polymer will act, as
described above, by forming hydrogen bonds with the other
components, forming a cohesive system comparable to the single
compound system. When used, in either the single compound or
multiple compound system, the polymer is employed in an amount of
about 0.1 to about 2%. Although the mixture per se does not
necessarily have an innate asymmetry, except perhaps in the
different size and/or conformation of the different compounds, the
combination in situ in the emulsion will self-assemble
asymmetrically.
[0013] An example of one embodiment of the single compound
structures is a group of anionic emulsifiers of the type that is
disclosed in PCT Publication No. WO 91/01970, the contents of which
are incorporated herein by reference. One class of compounds are
2-amidocarbonyl-benzoic acid surfactants having the formula (I):
wherein R.sub.1 and R.sub.2 are independently H or
(CH.sub.2).sub.nCH.sub.3, wherein n=8-22, provided that at least
one of R.sub.1 and R.sub.2 is H, wherein M.sup.+ is a cation
selected from the group consisting of H, Na, K, NH.sub.4 and
derivatives thereof (for example, basic amino acids), Ba, Ca, Mg,
Al, Ti, and Zr, and y is an integer of a value satisfying the
valency of M.sup.+. Particularly preferred among this class of
surfactants is a monovalent salt of stearyl amidobenzoic acid,
preferably a sodium salt, also known as RM1. This compound and
others of its type are commercially available from Stepan Company,
Northfield, Ill. These compounds are known surfactants, which have
previously been reported to form stable oil-in-water emulsions when
combined with a low HLB emulsifier, or a polymeric emulsifier.
However, in the present case, these emulsifiers can be used as the
sole emulsifier, at very low levels (i.e., as low as 0.25%) to
achieve a stable emulsion; this result is particularly unexpected
with an anionic emulsifier alone or at low levels. As can readily
be seen from the structure depicted above, these compounds contain
two hydrophobic groups, in the presence of the aromatic ring and
the long-chain fatty acid side chain, separated by two hydrophilic
groups, namely, the carboxylate and amide portions of the
molecule.
[0014] Another example of a compound meeting the requirements
outlined above is a compound, or a group of structurally-related
compounds, all known as surfactin. This material is naturally
occurring, being produced by fermentation of certain strains of
Bacillus subtilis, and is commercially available from Showa Denko,
KK, Japan. The structure of the molecule is unusual, being composed
of a large hydrophilic ring containing seven amino acids bonded to
each other by six peptide bonds and an ester bond, and having on
either side two short-chain hydrocarbons with free carboxyl groups
carrying anionic charges, (the ring and carboxyl groups
constituting the hydrophilic domain), with a hydrophobic domain
comprising a long chain fatty acid residue. A schematic
representation of this type of molecule is seen in FIG. 2. It will
readily be seen that these molecules possess an asymmetrical
arrangement of the hydrophilic and hydrophobic moieties, and also
have the desired rigidity in the presence of the amino acid ring
structure.
[0015] As a third example, and one in which there is not a single
compound, is a combination of xanthan, polyglucomannan, a high HLB
emulsifier, and a low HLB emulsifier. Such a combination is
available from Uniqema as part of the Arlatone Versaflex Series of
high performance emulsion stabilization systems.
[0016] The water-thin emulsions of the present invention have two
distinct advantages over prior art water-thin emulsions. The first
advantage is that the pseudoemulsifiers of this type are innately
mild, being relatively non-water soluble, and hence, non-reactive
with skin, and therefore are less irritating by nature than an
ethoxylated emulsifiers. In addition, the compounds of these
systems, even though not ordinarily effective as emulsifiers on
their own, have proven to be unusually effective in stabilizing
this type of emulsion, thereby improving even further the mildness
of the emulsions by reducing the amount of emulsifier needed. The
oil-in water emulsions of the invention ordinarily will contain no
more than about 3% total pseudoemulsifier, preferably no more than
2% pseudoemulsifiers, and more preferably, no more than 0.5%
pseudoemulsifier. Because of the unusual properties of these
pseudoemulsifiers, the emulsion is stable even in the substantial
absence of added emulsion stabilizers. It may, however, be desired
to thicken slightly the water-thin emulsion depending on the
desired nature of the final product. Therefore, it is possible to
add to the emulsion a small amount of one or more cosmetic powders,
not for stabilization, but merely to modify the viscosity of the
product. Examples of types of powders that can be used in the
present emulsion are silica powders, polymethylmethacrylate,
bismuth oxychloride, boron nitride, barium sulfate, mica, sericite,
muscovite, synthetic mica, titanium oxide coated mica, titanium
oxide coated bismuth oxychloride, talc, polyethylene, nylon,
polypropylene, acrylates/alkyl acrylates crosspolymer, acrylamide
copolymers, and the like. The powders can be used in an amount of
up to about 20%, but ordinarily the powders will be used in small
amounts, generally no greater than about 5% of the total weight of
the emulsion, more preferably no greater than 2%. In certain
embodiments, the emulsion will contain less than 0.5% by weight of
powders.
[0017] In order to prepare the water-thin emulsions of the
invention, the pseudoemulsifier is combined with any standard oil
and water emulsion components. The aqueous phase may be any
cosmetically acceptable water based material, such as deionized
water, or a floral water. The oil phase may be any cosmetically or
pharmaceutically acceptable oil, such an oil being defined for the
present purpose as any pharmaceutically or cosmetically acceptable
material which is substantially insoluble in water. As the oils can
perform different functions in the composition, the specific choice
is dependent on the purpose for which it is intended. The oils may
be volatile or non-volatile, or a mixture of both. For example,
suitable volatile oils include, but are not limited to, both cyclic
and linear silicones, such as octamethylcyclotetrasiloxane and
decamethylcyclopentasiloxane; or straight or branched chain
hydrocarbons having from 8-20 carbon atoms, such as decane,
dodecane, tridecane, tetradecane, and C8-20 isoparaffins.
[0018] Non-volatile oils include, but are not limited to, vegetable
oils, such as coconut oil, jojoba oil, corn oil, sunflower oil,
palm oil, soybean oil; carboxylic acid esters such as isostearyl
neopentanoate, cetyl octanoate, cetyl ricinoleate, octyl palmitate,
dioctyl malate, coco-dicaprylate/caprate, decyl isostearate,
myristyl myristate; animal oils such as lanolin and lanolin
derivatives, tallow, mink oil or cholesterol; glyceryl esters, such
as glyceryl stearate, glyceryl dioleate, glyceryl distearate,
glyceryl linoleate, glyceryl myristate; non-volatile silicones,
such as dimethicone, dimethiconol, dimethicone copolyol, phenyl
trimethicone, methicone, simethicone; and nonvolatile hydrocarbons,
such as isoparaffins, squalane, or petrolatum.
[0019] The ratio of oil phase:water phase in the emulsion is not
critical, and can range from about 10:90 to about 50:50, but is
more preferably from about 30:70 to about 40:60.
[0020] The pseudoemulsifier is ordinarily added to the phase in
which it is soluble, or to either phase if it is not soluble in
either, along with any active components which may be desired in
the emulsion, and all components mixed together at low pressure.
The mixture is then subjected to high pressure mixing. By "high
pressure" in the present context is meant a pressure of at least
about 15,000 psi, preferably at least about 25,000 psi, more
preferably about 35,000 psi; generally, a single pass through the
high pressure equipment is adequate to achieve an emulsion of the
desired type at higher pressures, although at lower pressures, more
than one pass may be required. The amount of pseudoemulsifier
employed is preferably no more than 2%, more preferably no more
than 1%. Amounts of as low as 0.25% can be employed, although about
0.5 to about 1% is generally preferred. It will be understood that
the amount of pseudoemulsifier and level of pressure can be varied
inversely, with a higher pressure treatment allowing the use of
lower levels of emulsifier to produce a stable emulsion, while
lower pressure treatments will ordinarily require a level of
emulsifier at the higher end of the effective range. The particle
size distribution is normally narrow, and very small, usually in
the range of about 50-150 nm, preferably with an average size of
about 50-100 nm, more preferably about 50 nm.
[0021] An oil-in-water emulsion so prepared can be used as such, or
it can be further used as a base to which an additional water
phase, particularly one enriched with active ingredients that may
be too temperature sensitive to be added to the high-temperature
pre-mix, can be added, under low pressure. This approach yields an
oil-in-water emulsion in the form of either a spray, lotion or
cream. In the preparation of such a composition, the oil-in-water
emulsion can be added to the water in an amount ranging from about
90:10 emulsion:water to 10:90 emulsion:water.
[0022] If desired, the viscosity of the resulting products can be
increased by the addition of water-soluble thickeners such as
acrylates crosspolymers and copolymers, carbomer, guar gum,
carageenan, cellulosics, mannan, sulfonic acid polymers, acrylamide
copolymer, xanthan gum and the like. Preferably, the amount of
thickener ranges between about 0.01 to about 1%, preferably no more
than about 0.5%.
[0023] In a particularly preferred embodiment, the water-thin
emulsion is added to a water-in-oil emulsion, so as to prepare a
multiple phase emulsion. This type of emulsion is valuable for a
number of reasons. First, it provides a means for incorporating
actives in the same vehicle which would not ordinarily be
compatible in the same phase, by incorporating them in different
phases. It also is a useful vehicle for delayed release of actives
on and into the skin, by virtue of the necessity of passing through
the multiple phases. Despite their clear value, however, such
emulsions are not frequently employed, as the additional phase
introduces further problems with stability, and therefore, they
frequently require the use of large quantities of emulsifiers
and/or emulsion stabilizers. It has now been found, unexpectedly,
that the water-thin emulsion can provide a basis for the
preparation of a multiple emulsion, serving as the outer water
phase, without the need for large quantities of emulsifiers. In
such preparation, the premade water-thin emulsion serves as the
water phase, and is mixed, under normal, low-pressure conditions,
with a premade standard water-in-oil emulsion. The two emulsions
are preferably combined in a ratio of about 80 water-thin
emulsion:20 water-in-oil emulsion up to 50:50
water-thin:water-in-oil, to yield a stable multiple emulsion.
Surprisingly, these multiple emulsions can be prepared with no more
than 2% emulsifiers, and preferably no more than about 1.5%
emulsifiers total in the multiple emulsion.
[0024] Even more unexpectedly, the multiple emulsions can be
prepared with an even number of phases, e.g., four phases, rather
than the standard uneven number ordinarily found in multiple
emulsions, such as water-in-oil-in-water. This is made possible by
the small droplet size of the oils in the water-thin emulsion,
which essentially presents itself as water to a standard emulsion,
and is therefore readily incorporated without the addition of large
amounts of emulsifiers.
[0025] Generally speaking, the multiple emulsion can be prepared
with little or no "traditional" emulsifier, a traditional
emulsifiers being one which, unlike the pseudoemulsifiers, are
capable of stabilizing emulsions on their own, even at relatively
low levels. When combined with a water-thin oil-in-water emulsion
to make the multiple emulsion, the multiple emulsion may employ
small amounts of a traditional oil-in-water emulsifier. Examples of
useful oil-in-water emulsifiers include, but are not limited to,
sorbitol derivatives, such as sorbitan monolaurate and polysorbate
20; ethoxylated alcohols such as laureth-23, ethoxylated fatty
acids such as PEG-1000 stearate; amidoamine derivatives such as
stearamidoethyl diethylamine; sulfate esters such as sodium lauryl
sulfate; phosphate esters such as DEA cetyl phosphate; fatty acid
amine salts such as TEA stearate; and mixtures thereof. Additional
examples can be found in McCutcheon's Emulsifiers and Detergents,
2000, the contents of which are incorporated herein by reference.
If used, this type of emulsifier is incorporated in quantities of
no more than about 2% by weight of the multiple emulsion,
preferably no more than 1%, and more preferably, no more than about
0.5%. Stabilizers or thickeners, if used at all, can be employed as
described for the water-thin emulsion alone.
[0026] The compositions of the invention can be used for any
cosmetic or pharmaceutical purpose in which an standard or multiple
emulsion is normally useful. For cosmetic purposes, the emulsions
can be used in makeup products as well as skin-care products. In
such cases, it may be desirable to incorporate into the emulsion
additional components usually associated with the desired cosmetic
uses, such as additional preservatives, fragrances, emollients,
antiseptics, antiinflammatories, antibacterials, stabilizers,
sunscreens, antioxidants, vitamins, pigments, dyes, humectants, and
propellants, as well as other classes of materials the presence of
which in the compositions may be cosmetically, medicinally, or
otherwise desired. Such components can be found in the CTFA
International Cosmetics Ingredients Dictionary, supra.
[0027] For pharmaceutical or therapeutic cosmetic use, the emulsion
can incorporate any variety of topically applied therapeutic
agents, particularly those that will benefit from a delayed release
of active agents. Examples include, but are not limited to, agents
for the eradication of age spots, keratoses and wrinkles,
analgesics, anesthetics, anti-acne agents, antibacterials,
antiyeast agents, antifungal agents, antiviral agents, antidandruff
agents, antidermatitis agents, antipruritic agents, antiemetics,
antimotion sickness agents, anti-inflammatory agents,
antihyperkeratolytic agents, anti-dry skin agents, antiperspirants,
antipsoriatic agents, antiseborrheic agents, hair conditioners and
hair treatment agents, antiaging agents, antiwrinkle agents,
antiasthmatic agents and bronchodilators, sunscreen agents,
antihistamine agents, skin lightening agents, depigmenting agents,
vitamins, corticosteroids, self-tanning agents, hormones,
retinoids, such as retinoic acid, 13-cis retinoic acid, and
retinol, topical cardiovascular agents, clotrimazole, ketoconazole,
miconozole, griseofulvin, hydroxyzine, diphenhydramine, pramoxine,
lidocaine, procaine, mepivacaine, monobenzone, erythromycin,
tetracycline, clindamycin, meclocyline, hydroquinone, minocycline,
naproxen, ibuprofen, theophylline, cromolyn, albuterol, topical
steroids such as hydrocortisone, hydrocortisone 21-acetate,
hydrocortisone 17-valerate, and hydrocortisone 17-butyrate,
betamethasone valerate, betamethasone diproprionate, triamcinolone
acetonide, fluocinonide, clobetasol, proprionate, benzoyl peroxide,
crotamiton, propranolol, promethazine, vitamin A palmitate, vitamin
E acetate and mixtures thereof.
[0028] The invention is further illustrated by the following
non-limiting examples.
EXAMPLES
Example 1
[0029] This example illustrates the preparation of an oil-in-water
emulsion of the invention.
1 Weight % Material Batch 1 Batch 2 Batch 3 Water Phase Deionized
water 65.25 64.70 62.50 Disodium EDTA 0.10 0.10 0.10 Methyl paraben
0.05 0.05 0.05 Butylene glycol 3.00 3.00 3.00 phenoxyethanol 0.40
0.40 0.40 Oil Phase Behenyl alcohol 0.75 0.75 0.75 Pentaerythrityl
tetraoctanoate 30.00 30.00 -- Stepan RM1 0.50 1.00 0.50 C12-15
alkyl benzoate -- -- 30.00
[0030] The water phase materials are heated to 85-90.degree. C. The
oil phase materials are heated to 85.degree. C. The oil phase
materials are added to the water phase materials using a Silverson
(low pressure) homogenizer. The batch is then run through a DEE/BEE
2000 homogenizer at 40,000 psi, and cooled to room temperature in
the machine.
Example 2
[0031] This example illustrates the use of the emulsions prepared
above in creating a variety of low emulsifier skin care
products.
2 A. Low emulsifier creme Material Weight % Phase I Deionized Water
19.00 acrylamide copolymer (1.5%) 10.00 Glycerine 10.00
antiinflammatory polysaccharide 1.00 Phase II Batch 3 39.60
Acrylates/C10-30 alkyl acrylates Crosspolymer (2%) 20.00
triethanolamine 0.40
[0032] Phase I and Phase II components are separately premixed by
propeller mixing. The two phases are then mixed to homogeneity with
a propeller or paddle.
3 Material Weight % B. Low emulsifier milk lotions Batch 2 97.00
99.00 Magnesium ascorbyl phosphate 3.00 -- N-acetyl glucosamine --
1.00 C. Low emulsifier cleanser Phase I Deionized water 18.70
methyl paraben 0.10 Phase II glycerine 10.00 Phase III Acrylamide
copolymer (1.5%) 10.00 Phase IV Acrylates/C10-30 alkyl acrylates
20.00 crosspolymer (2%) Phase V Batch 2 39.60 Phase VI
triethanolamine 0.40 deionized water 0.50 Phase VII Germall 115
0.20 deionized water 0.50
[0033] Phase I materials are heated to 75.degree. C., and cooled to
room temperature. Phases II, III, and IV are added to Phase I under
propeller agitation. After addition of Phase IV, viscosity
increases, requiring a change to a paddle. Phases V, VI and VII are
then added to the mixture, and mixed to homogeneity.
Example 3
[0034] This example illustrates the process of preparing a multiple
emulsion according to the invention.
4 A. A water-in-oil phase is prepared as follows: Material Weight %
Phase I Cyclomethicone/dimethicone 5.00 Phenyltrimethicone 5.00
Dimethicone/copolyol crosspolymer 7.00 Cyclomethicone 1.00
Dimethicone 8.00 Phase II Xanthan gum 0.20 Deionized water 64.30
Sodium chloride 1.00 Butylene glycol 5.00 Parabens 0.50
[0035] The oil phase ingredients are combined together, and the
water phase ingredients are combined together. The water phase is
then slowly added to the oil phase, and homogenized until
uniform.
5 B. Water-thin, low emulsifier emulsion Material Weight % Phase I
deionized water 32.50 Arlatone Versaflex High 1.00 Performance
Emulsion Stabilizer* Phase II Deionized water 32.05 Methyl paraben
0.20 Butylene glycol 3.00 Phenoxyethanol 0.40 Phase III Behenyl
alcohol 0.75 Pentaerythrityl tetraethylhexanoate 30.00
Beta-carotene 0.10 *Uniqema
[0036] In Phase I, the emulsifier is added to water at 80.degree.
C. Phase II ingredients are added to Phase I at 80.degree. C. Phase
III ingredients are combined and then homomixed with Phase I and II
ingredients at greater than 10,000 rpm for 5 minutes. The combined
components are then passed through a microfluidizer at 16,000 psi
three times to achieve a water-thin emulsion.
6 C. Multiple emulsion Material Weight % Polysorbate 20 0.20
Carbopol 1.00 O/W emulsion from B. 78.80 W/O emulsion from A.
20.00
[0037] The O/W emulsion is combined with the Carbopol using static
mixing. Polysorbate 20 is then added. The W/O emulsion is slowly
added to the O/W phase utilizing static mixing. When the addition
is complete, the mixing is continued for about 5 minutes until the
multiple emulsion is uniform.
[0038] Similar positive results are obtained in preparing a
multiple emulsion as described above, utilizing RM1 as the
pseudoemulsifier, and combining the O/W emulsion and the W/O
emulsion in a ratio of 60:40.
* * * * *