Note: Descriptions are shown in the official language in which they were submitted.
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STABLE CLEANSING COMPOSITIONS CONTAINING ACTIVE AGENTS
This application claims the benefit of U.S. Provisional Application No.
60/096,643, filed August 14, 1998.
The present invention relates to stable personal cleansing compositions
comprising: at least one stabilizing agent chosen from specific ethoxylated
solubilizers, particularly polyethylene glycol ("PEG") ethers of fatty
alcohofs; at least
one active agent, particularly a lipophilic .compound; and at least one
surfactant.
The present invention also relates to a process for stabilizing cleansing
compositions containing at least one active agent, particularly at least one
lipophilic
compound.
Personal cleansing compositions are useful for maintaining good skin
hygiene. In so doing, personal cleansing compositions should be able to
cleanse
the skin of excess sebum, make-up residues, and particularly compositions
which
have waterproof or non-transfer properties. Conventional personal cleansing
compositions use soaps based on alkali salts of fatty acids, synthetic
surfactants,
or mixtures of soaps and synthetic surfactants. Typically, these compositions
are
in the form of solid soap bars. These conventional compositions, however, have
several disadvantages. In particular, conventional compositions can be harsh,
removing the hydro-lipidic film of the skin, leaving the skin extremely dry.
Moreover, these soap bar compositions can exhibit poor rinsability, leaving a
film
on the skin after rinsing. Cleansing compositions based only on synthetic
surfactants, i.e., without soaps, can have problems with their foam. Often the
foam
obtained with these compositions is abundant but does not have the fine and
dense texture offered by soaps.
Personal cleansing compositions can also act as delivery systems for active
agents. "Active agents," in accordance with the present invention, include
compounds typically identified as such by those of ordinary skill in the art,
for
example moisturizers, emollients, and uv filters, as well as fragrances.
However,
certain active agents can disrupt the stability of conventional cleansing
compositions. Lipophilic compounds, and fragrances in particular, especially
at
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higher concentrations, can disrupt the stability of cleansing compositions and
often
suppress foam.
It is therefore an object of the present invention to provide a personal
cleansing composition which contains at least one active agent, particularly
at least
one lipophilic agent, yet exhibits a stable viscosity profile.
It is another object of the present invention to provide a personal cleansing
composition which can be fragranced yet exhibits a stable viscosity profile.
It is a further object of the present invention to provide thickened,
fragranced-cleansing compositions with good foaming and conditioning
properties.
It is yet another object of the present invention to provide a process for
stabilizing personal cleansing compositions containing at least one active
agent,
particularly at least one lipophilic active agent.
Accordingly, the present invention relates to stable personal cleansing
compositions comprising at least one stabilizing agent chosen from ethoxylated
solubilizing agents, at least one active agent, and at least one surfactant.
These
compositions can further comprise water.
The present invention also relates to a process for stabilizing personal
cleansing compositions comprising at least one active agent and at least one
surfactant by including therein at least one stabilizing agent chosen from
ethoxylated solubilizing agents.
Thus, the subject of the present invention is a personal cleansing
composition containing at least one active agent and at least one surfactant,
and
further comprising at least one stabilizing agent, wherein the viscosity
profile of the
composition remains relatively constant, i.e., the composition is stable.
Active
agents useful in the present invention include, but are not limited to,
lipophilic
compounds such as retinol or its derivatives, vitamin E or its derivatives,
bisabolol,
oils, particularly vegetable oils, and fragrances. More preferably, the active
agent
is a fragrance. The surfactant used in the present invention is preferably an
anionic surfactant. The stabilizing agent is preferably chosen from
ethoxylated
solubilizing agents. More preferably, the stabilizing agent is chosen from
polyethylene glycol ethers of fatty alcohols. The inventive composition can
have
conditioning properties and foaming properties as well.
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A "stable" composition in accordance with the present invention is either a
composition whose viscosity does not change more than 20% from its initial
value
within 8 weeks at 45°C or a composition whose initial viscosity is at a
level useful in
a cleansing composition, e.g., not lower than about 5000 cps. "Initial
viscosity" is
the viscosity 24 hours after manufacture of a cleansing composition. The
stability
of a compound can be a predictor of shelf life. For example, a compound whose
viscosity does not change more than 20% within 8 weeks at 45°C might
have a
shelf life of about two years at room temperature.
The present composition thus has the stability characteristics discussed
above and contains at least one active agent, at least one surfactant, and at
least
one stabilizing agent chosen from specific solubilizers. By contrast,
conventional
cleansing compositions that do not contain solubilizers can exhibit a change
in
viscosity of greater than 20% after 8 weeks at 45°C. Furthermore, while
it is
generally known to use solubilizers, including ethoxylated materials, to help
solubilize fragrances, some solubilizers can disrupt the viscosity of
cleansing
compositions, causing the initial viscosity to be too low to achieve the
objectives of
the present invention, e.g., about 5000 cps or less. For example, the
ethoxylated
solubilizer PPG-26 Buteth-26 PEG-40 hydrogenated castor oil (a mixture sold by
Wackherr under the name SOLUBILISANT LRI) disrupts the viscosity of a
fragranced cleansing composition, resulting in an initial viscosity of less
than about
5000 cps.
The inventor has unexpectedly discovered that specific ethoxylated
solubilizing agents; particularly polyethylene glycol (PEG) ethers of fatty
alcohols;
can stabilize compositions containing active agents, particularly lipophilic
active
agents. In particular, cleansing compositions comprising these specific
ethoxylated
solubilizing agents, particularly cleansing compositions which also comprise a
fragrance, do not exhibit the change in viscosity and do not have unacceptably
tow
viscosities, as described above. The PEG ethers of fatty alcohols used
according
to the invention may preferably be chosen from compounds having formula (I),
below:
CH3RCHz(OCH2CH2) ~OH (I)
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wherein:
R is chosen from alkyl and alkylene fatty chains having from about 10 to
about 18 carbons; and,
n represents an average value of from about 10 to about 30.
R therefore refers to the fatty alcohol chain and n shows the average
number of moles of ethylene oxide or the degree of ethoxylation. The
solubilizing
properties of the compositions are related to R, n, and the degree of
saturation of
the fatty chain. The longer the chain making up R, the more lipophilic the
compound, and the higher the n, the more hydrophilic the compound. A person of
ordinary skill in the art will know how to vary the parameters to achieve a
compound which is effective as a solubilizer and, similarly, that the choice
of n and
R depend on the compound that is being solubilized.
A person of ordinary skill will also recognize that the numbers used in the
definition of n and R, above, represent preferred embodiments, and that
depending on how each parameter is selected, R and n may vary outside the
preferred range . Thus, the inventor has used the term "about" in defining n
and R
to represent values, including average values, in combination sufficient to
achieve
stabilization of compositions of the invention containing active agents,
particularly
lipophilic active agents, such as fragrances:
The preferred PEG ethers of fatty alcohols of formula (I) have an R with a
chain length from 10 to 16 carbons, even more preferably 14 to 16, and an
average
n value from 15 to 25, even more preferably 20. Particularly preferred are
CETETH-20, which contains 16 carbons in its fatty chain, i.e., including the
portion
of its fatty chain corresponding to R in formula (I) above as well as the two
additional carbon atoms on either side of R, and an n of average value 20, or
STEARETH-20, which has a 18-carbon chain (where the chain length is as defined
above for CETETH-20) and an n of average value 20, both available from ICI
Americas.
When the active agent is a fragrance, the fragrance is present in the
inventive composition in an amount up to 5%, preferably in an amount ranging
from
2 to 5%. Furthermore, the ratio of the PEG ethers of fatty alcohols to the
fragrance
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in the inventive composition can range from about 1:4 to about 5:1, based on
weight. The fragrances) can be chosen from conventional fragrances suitable
for
use in personal cleansing compositions.
The composition of the present invention can also contain one or more
anionic surfactants, or one or more other surfactants. Anionic surfactants
suitable
for use in the inventive composition include, but are not limited to alkyl
sulfates,
alkyl ether sulfates, alkali metal alkylarylsulfonates, alkali metal,
alkanolamines,
salts of alkyl polyether carboxylic acids, salts of alkylphenyl polyether
carboxylic
acids, and N-acylamino acids. These anionic surfactants are preferably present
in
the composition in concentrations of from 8% to 25% and can provide foam
properties.
Thus, a preferred formulation of the present composition contains:
a) PEG ethers) of fatty alcohols in an amount of from 2% to 25%,
b) anionic surfactants) in an amount of from 8% to 25%,
c) fragrances) in an amount of from 2% to 5% and
d) water.
All percentages and/or ratios used herein are by weight of the total
composition unless otherwise indicated.
Other surfactants may be used alone, or preferably, in combination with the
anionic surfactants. For example, certain cleansing compositions, such as baby
shampoos, that are intended to be particularly mild may contain amphoteric
surfactants. Preferred classes of amphoteric surfactants include: N-alkylamino
acids, N-alkylamine oxides, alkylimidazolines, betaines containing fatty
chains, or
amidobetaines derived from fatty acids, or salts of amino acids such as N-
lauryl ~i-
alanine and N-stearyl ~3-alanine. Preferred nonionic surfactants of the
following
classes may be used: alkanolamides, alkyl ethers of polyglycerols, alkyl
ethers of
polyethylene glycols, alkyl glucosides, copolymers of ethylene oxide and
propylene
oxide.
The composition according to the invention is advantageously in a thickened
form, preferably a gel. Therefore, the composition preferably also comprises
at
least one thickener or gelling agent. The thickeners or gelling agents can be
either
synthetic or natural and are preferably chosen from carboxylic acid polymers,
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crosslinked polyacrylate polymers, polyacrylamide polymers, polysaccharides,
gums, gelatins, vinyl ether/maleic anhydride copolymers, and crosslinked poly
(N-
vinyipyrrolidones).
The at least one thickener or gelling agent is preferably present in the
composition in an amount ranging from 0.1 % to 2%, more preferably from 0.25%
to
1 % and even more preferably from 0.4% to 0.8%. The thickener or gelling agent
can be a single compound as well as a mixture of two or more compounds.
The composition of the present invention can also comprise any ingredient
usually used by any person of skill in the art in the personal care area. Such
ingredients. can be, but are not limited to, adjuvants such as rJatural and
synthetic
polymers, colorants, preservatives, antioxidants, medicaments, moisturizers,
sunscreen agents, germicides, deodorants, opacifiers, pearlizing agents, oils,
waxes, thickeners for the oily phase, proteins, amino acids, healing agents,
solvents, humectants, emollients, buffers, pH adjusters, chelating agents, and
abrasives. A preferred embodiment includes a pearlizing agent.
A person skilled in the art will choose the other ingredients usually
associated with a like composition in a way that will substantially maintain
the
advantages of the present invention.
Another subject of the present invention is a process for stabilizing personal
cleansing compositions containing at least one active agent, by including
therein
specific ethoxylated solubilizing agent(s). In a preferred embodiment, PEG
ethers
of fatty alcohols are included in cleansing compositions comprising at least
one
fragrance.
The following examples are intended to illustrate the invention and are not
intended to be limiting. All ingredients are named using the CTFA
nomenclature,
as set forth in the Seventh Edition of International Cosmetic Ingredient
Dictionary
and Handbook.
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Example 1 ,Comparative)
The following composition was made using no solubilizer for the active
agent, in this case a fragrance.
Ingredients %w/w
Water q ~s~
AcrylateslC10-30 alkyl 0.40
acrylate crosspoiymer
Disodium EDTA 0.05
Methylparaben 0.20
Propylparaben 0.15
Sodium laureth sulfate 12.35
Cocamidopropyl betaine 8.60
Triclosan 0.05
Glycol distearate 2.00
Cocamide MEA 2.00
Sodium hydroxide 0.10
Polyquaternium-7 1.25
Phenoxyethanol 0.30
Corn oil 0.10
BHT 0.07
Fragrance 4.00
100.00
A first premix of sodium hydroxide and water was prepared by mixing the
two ingredients with a magnetic stir bar at 25°C until uniform.
A second premix was prepared by mixing polyquaternium-7 and water
together at 25°C using a magnetic stir bar.
A third premix of fragrance, corn oil and BHT was prepared at 35°-
40° C
using a magnetic stir bar.
Water was heated to 75°-80° C. The following ingredients
were mixed into
the water until dissolved, while maintaining the 75°-80° C
temperature, sequentially
as follows:
- acrylateslC10-30 alkyl acrylate crosspoiymer;
- disodium EDTA, methylparaben and propylparaben,
- sodium laureth sulfate,
- cocamidopropyl bentaine and triclosan.
Mixing continued until the dispersion appeared uniform. The mixture was
cooled to 70°-75° C and glycol distearate added and mixed in
until melted and
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dissolved. Cocamide MEA was then mixed until dissolved and the mixture was
uniform. The blend was then cooled until 65°-70° C wherein the
first premix was
blended in until the mixture was uniform. After cooling until 30°-
35° C, the second
premix was mixed in until uniform, followed by phenoxyethanol which was also
mixed in until uniform. Finally, the 30 premix was added and mixed in until
the
blend was uniform. The mixture was cooled to 25° C.
The viscosity of the composition was measured 24 hours after manufacture
using a Brookfield RVT using spindle #5 rotating at 20 rpm for 1 minute at
25°C.
The viscosity measurements are shown below in Table 1. The initial viscosity
of
15450 centipoise (cps) dropped to 7650 cps after 2 weeks at 45°C. It
remained
fairly constant after that with a reading of 8750 cps after 8 weeks at
45°C. Thus,
when no solubilizer is used, the viscosity drops about 50% in two weeks and
remains at about that level.
Table 1
Time Viscosi
Initial 15450 cps
After 2 weeks @ 45°C 7650 cps
After 8 weeks @ 45°C 8750 cps
A similar drop in viscosity (50% drop or more) was observed after one or
more freeze-thaw cycles. The freeze-thaw process was carried out by placing
the
composition in a chamber that cycled between a temperature of -10°C and
a
temperature of 25°C. The composition was maintained at each temperature
for
about 12 hours, with less than 1 hour transition between the two temperatures.
Thus, one cycle was 24 hours in length. After one cycle the viscosity dropped
from
the initial 15450 cps to 7100 cps, after fi cycles the viscosity was 6100 cps.
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Table 2
Time Thaw
(Freeze-Thaw Cvcle~ (C~sa
Initial 15450
After 1 7100
After 6 6100
Thus, when no solubilizer is used, the viscosity reduction is about 55%.
Example 2 lComparative~
Ingredients %w/w
Water q.s.
Acrylates/C10-30 alkyl 0.40
acrylate crosspolymer
Disodium EDTA 0.05
Methylparaben 0.20
Propylparaben 0.15
Sodium iaureth sulfate 12.35
Cocamidopropyl betaine 8.60
Triclosan 0.05
Glycol distearate 2.00
Cocamide MEA 2.00
Sodium hydroxide 0.10
Polyquatemium-7 1.25
Phenoxyethanol 0.30
Corn oil 0.10
BHT 0.07
PPG-26 Buteth-26 PEG-40 4.00
hydrogenated castor oil
Fragrance 4.00
TOTAL 100.00
The product in this example was made according to the process outlined in
Example 1, except that the solubilizer was premixed along with the fragrance,
the
corn oil and the BHT. The product was made with 4% PPG-26 Buteth-26 PEG-40
Hydrogenated castor oil as a solubilizer for the fragrance. The viscosity of
the
initial composition was too low, i.e., less than 5000 cps. Thus, the viscosity
was
aesthetically unacceptable to achieve the objectives of the present invention
and
additional stability studies were not warranted.
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Example 3 iLComparative)
I ngred Tents %w/w
Water q.s.
Acrylates/C10-30 alkyl 0.40
acrylate crosspolymer
Disodium EDTA 0.05
Methylparaben 0.20
Propylparaben 0.15
Sodium laureth sulfate 12.35
Cocamidopropyl betaine 8.60
Triciosan 0.05
Glycol distearate 2.00
Cocamide MEA 2.00 v
Sodium hydroxide 0.10
Polyquatemium-7 1.25
Phenoxyethanol 0.30
Corn oil 0.10
BHT 0.07
Polysorbate-20 4.00
Fragrance 4.00
TOTAL 100.00
The product in this example, and in the subsequent examples, was made in
the same manner as Example 2. The product in this Example 3 was made with 4%
Polysorbate-20, a polyoxyethylene sorbitan laurate ester used as a solubilizer
to
replace the 4% PPG-26 Buteth-26 PEG-40 Hydrogenated castor oil. The viscosity
was too low, i.e. less than 5000 cps, and the product was deemed aesthetically
unacceptable to achieve the objectives of the present invention.
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Example 4 llnventive)
Ingredients %w/w
Water q.s.
Acrylates/C10-30 alkyl 0.40
acrylate crosspolymer
Disodium EDTA 0.05
Methylparaben 0.20
Propylparaben 0.15
Sodium laureth sulfate 12.35
Cocamidopropyl betaine 8.60
Triclosan 0.05
Glycol distearate 2.00
Cocamide MEA 2.00
Sodium hydroxide 0.10
Polyquaternium-7 1.25
Phenoxyethanol 0.30
Corn oil 0.10
BHT 0.07
Fragrance 4.00
STEARETH-20 2.00
100.00
The product in this example was made by replacing the PPG-26 Buteth-26
PEG-40 hydrogenated castor oil of Example 2 with STEARETH-20. The viscosity
was measured on a Brookfield RVT' viscometer using spindle #6 under the same
conditions as those in Example 1. The viscosity measurements are shown below
in Table 3. This initial viscosity of 7160 cps dropped only to 5820 cps (a
18.7%
drop) after 2 weeks at 45°C. The viscosity showed a slight improvement
over time
with a reading of 6740 cps (a 5.9% reduction in viscosity) after 8 weeks at
45°C.
The freeze-thaw stability measurements are shown below in Table 4. The freeze-
thaw stability was also improved showing a reduction of the viscosity to 6360
cps
(11.2%) reduction after 1 cycle and a viscosity of 7120 cps (a reduction of
0.6%)
after 6 cycles. This shows that STEARETH-20 did not negatively affect the
viscosity as compared to the PPG-26 Buteth-26 PEG-40 hydrogenated castor oil
of
Example 2. In particular, the composition comprising STEARETH-20 exhibited an
acceptable initial viscosity and a relatively constant viscosity profile,
whereas the
composition containing the PPG-26 Buteth-26 PEG-40 hydrogenated castor oil had
an initial viscosity that was too low.
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Table 1
Time Viscosity
(Weeksai _~Cps)
Initial 7160
After 2 weeks at 45°C 5820
After 8 weeks at 45°C 6740
Table 2
Time Viscosity
Freeze-Thaw Cycles Cps)
After 1 6360
After 6 7120
Example 5 (Inventive
I ng red Tents %w/w
Water q.s.
Acrylates/C10-30 alkyl 0.40
acrylate crosspolymer
Disodium EDTA 0.05
Methylparaben 0.20
Propylparaben 0.15
Sodium laureth sulfate 12.35
Cocamidopropyl betaine 8.60
Triciosan 0.05
Glycol distearate 2.00
Cocamide MEA 2.00
Sodium hydroxide 0.10
Polyquaternium-7 1.25
Phenoxyethanol 0.30
Corn oil 0.10
BHT 0.07
Fragrance 4.00
CETETH-20 4.00
100.00
The product in this example was made in the same manner as in Example 4
by replacing the STEARETH-20 with CETETH-20. The composition of Example 5
exhibited an initial viscosity comparable to the composition containing
STEARETH-
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20. Although stability studies were not carried out, the result would be
expected to
be similar to those of Example 4.
