Note: Descriptions are shown in the official language in which they were submitted.
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SKIN-BALANCE MOISTURIZING CREAM
This application claims priority to U.S. provisional application serial no.
60/
153,005 filed September 9, 1999, the disclosure of which is hereby
incorporated by
reference.
FIELD OF THE INVENTION
The invention relates to a non-comedogenic skin care composition that
effectively moisturizes the skin through a combination of the softening
effects of
emollients with the moisture retaining action of humectants and coating
activities of
lubricants, to counteract the effect of moisture loss, thereby keeping skin
soft, smooth
I o and supple.
BACKGROUND OF THE INVENTION
It is known that skin protection and a long lasting moisturizing effect is
best
achieved through water-in-oil emulsions. See, for example, U.S. Patent No.
3,818,105.
However, such emulsions compromise aesthetics due to their oily and greasy
after feel
when applied to the skin. Certain water-based products, i. e., oil-in-water
emulsions, are
oil-free and non-greasy but lack sufficient moisturizing properties. U.S.
Patent No.
4,389,419 discloses a skin care water-out emulsion composition to moisturize
and
condition the skin comprising mixture of petrolatum or mineral oil, a
quaternary
2o ammonium emulsifier, a fatty alcohol and a fatty ester emollient. While
this
composition counteracts the effect of moisture loss, thereby keeping the skin
soft,
smoothe and supple, the presense of petrolatum and mineral oils makes the
composition
difficult to emulsify as well as render it cosmetically unacceptable.
The problems associated with an effective skin moisturizing product are even
more profound in the teenage market where the mode of moisturizing is seen as
conflicting with keeping skin free of pimples and comedones. Teenagers
normally avoid
moisturizers because they are perceived to worsen problematic skin. However,
adequate
hydration is necessary for healing and to reduce dryness, thereby, maintaining
the
integrity of the skin's barrier function.
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Accordingly, there remains a need for an effective skin moisturizing
composition
that is effective at moisturizing the skin without the leaving an oily or
greasy feel to the
skin and is non-comedogenic.
It has surprisingly been discovered that a light, oil-free, non-greasy, water
based
cream emulsion, that is easy to spread, quick absorbing, long lasting, and non-
comedogenic can be obtained through a specific combination of emollients,
humectants
and keratolytic agent.
SUMMARY OF INVENTION
Accordingly, the invention relates to an oil-free skin care composition for
moisturizing the skin comprising:
(a) a humectant comprising glycerin and propylene glycol;
(b) an emollient comprising isohexadecane, cylcomethicone,
dimethicone, dimethicone copolyol and trimethylsiloxysilicate;
(c) a keratolytic agent; and
(d) water.
The skin care compositions according to the invention accomplish effective
moisturization through a combination of the softening effects of emollients
with the
moisture retaining action of humectants and coating activities of lubricants.
The
combination of ingredients counteract the effect of moisture loss, thereby
keeping skin
soft, smooth and supple. The compositions according to the invention are non-
comedogenic and have long lasting moisturizing effects without the use of
occlusive
materials.
DETAILED DESCRIPTION
The invention relates to a skin care composition for moisturizing the skin
comprising a humectant, an emollient, a keratolytic agent and water. The skin
care
composition according to the invention is an oil-free, water-based, i. e., oil-
in-water
emulsion. In the context of the invention, the phrase "oil-free" means free
from
petrolatum or any ingredient with the name "oil" in its nomenclature,
including, for
3o example, mineral oil.
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The skin care compositions according to the invention comprise at least one
humectant which increases the water content of the top layer of the skin by
actively
attracting and retaining the moisture where it is needed to relieve dry skin.
The skin's
moisture level is thereby increased without feeling heavy and occlusive.
The humectant is preferably present in an amount of from about 2 to about 10
wt.
%, based on the total composition. Suitable humectants for use in the present
invention
include glycerin, propylene glycol, and mixtures thereof. In a particularly
preferred
embodiment, the humectant is a mixture of from about 1 to about 5 wt.% of
glycerin and
from about 1 to about 5 wt. % of propylene glycol, even more preferably, from
about 2
1 o to about 3 wt. % glycerin and from about 2 to about 3 wt. % propylene
glycol, based on
the total composition.
The skin care composition according to the invention also contain an
emollient.
The emollient useful in the skin care composition according to the invention
contains a
mixture of isohexadecane, cyclomethicone, dimethicone, dimethicone copolyol,
and
15 trimethylsiloxysilicate. The emollients act indirectly to soften the
stratum corneum by
slowing down the loss of moisture to the envirorunent, allowing the skin to re-
moisturize itself from within.
The dimethicone and trimethylsiloxysilicate offers skin protection and long
lasting lubricity with a light touch and do not interfere with the skin's
transpiration. The
2o combination of cyclomethicone and dimethicone copolyol is normally used for
preparing
water-in-cyclomethicone emulsions. In the skin care compositions according to
the
invention, the cylcomethicone and dimethicone copolyol is used as a delivery
system for
the emollients. Being a water-based emulsion, i. e., oil-in-water, once
applied to the skin,
the volatile components evaporate, imparting a cooling effect on the skin as
well as
25 leaving behind the heavier, more effective skin conditioning agents on the
skin.
In addition to providing emolliency, the dimethicone copolyol is a silicone
glycol
copolymer that provides humectant benefits in addition to emolliency. Examples
of
commercially available dimethicone copolyols useful herein sold by Dow Corning
Corporation are DC 190, DC 193, DC Q2-5220, DC 2501 Wax, DC 2-5324 fluid, and
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DC 3225C (this later material being sold as a mixture with cyclomethicone).
Cetyl
dimethicone copolyol is commercially available as a mixture with polyglyceryl-
4
isostearate (and) hexyl laurate and is sold under the tradename ABIL® WE-
09
(available from Goldschmidt).
Trimethylsiloxysilicate is a polymeric material corresponding to the general
chemical formula [(CH2)3 Si0~~2]X [Si02]y, wherein x is an integer from about
1 to about
500 and y is an integer from about 1 to about 500. A preferred commercially
available
trimethylsiloxysilicate is sold by Dow Corning as a mixture with dimethicone
as DC
593.
1 o Suitable dimethicones useful as an emollient in the skin care composition
of the
invention are commercially available from Dow Corning as the Dow Corning 200
series.
A particularly preferred dimethicone for use in the skin care compositions of
the
invention is available from Dow Corning is DC200/350cst.
In a preferred embodiment, the skin care composition according to the
invention
15 comprises from about 3 t about 15 wt.% of the emollient. Particularly
preferred is a
combination of from about 1.0 to about 4.0 wt.% isohexadecane, from about 1.0
to about
5.0 wt.% of DC 3225C, and from about 0.5 to about 3.0 wt.% of DC 593 and from
about 0.5 to about 3.0 DC 200/350 wt.% cst based on the total weight of the
composition.
20 The keratolytic agent useful in the skin care compositions according to the
invention should be effective in preventing pimples and comodones. Suitable
keratolytic
agents include alpha hydroxy acids and beta hydroxy acids. The most preferred
keratolytic agent is salicylic acid. Preferably, the keratolytic agent is
present in the skin
care compositions according to the invention at from about 0.25 to about 2.0
wt.%, more
25 preferably from about 0.5 to about 2.0 wt. %, based on the total
composition.
The skin care composition according to the invention preferably contains an
effective stabilizing amount of an emulsifier. Preferably, the emulsifier is
present at
from about 1.0 to about 10.0, more preferably from about 3.0 to about 6.0,
weight
percent, based on the total composition. Any emulsifier that is compatible
with the
3o components of the composition can be employed. However, it has been
discovered that
when stearic acid is the primary emulsifier, it also helps provide the skin
feel of the
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product. Additionally, when used as co-emulsifiers, cetyl alcohol and stearyl
alcohol
also provide lubricating properties for the skin. Accordingly, in a preferred
embodiment,
the emulsifier used in the skin care composition of the invention is a mixture
of from
about 0.5 to about 3.0, more preferably form about 1 to about 2, weight
percent, based
on the total composition, each of stearic acid, cetyl alcohol and stearyl
alcohol.
The emulsion can be further stabilized by inclusion of a small quantity of a
thickener. The thickener is used in amount of about 0.01 to about 10% by
weight based
upon the weight of the coating composition. The range of about 0.01 to about
5% by
weight is preferred, with the range of about 0.03 to about 1.0% by weight
being
1 o particularly preferred. The thickener can be a non-associative thickener
or stabilizer,
such as a homopolymer or a copolymer of an olefinically unsaturated carboxylic
acid or
anhydride monomers containing at least one activated carbon to carbon olefinic
double
bond and at least one carboxyl group or an alkali soluble acrylic emulsion.
Alternatively, an associative thickener or stabilizer can be used, such as a
hydrophobically modified alkali soluble acrylic emulsion or a hydrophobically
modified
nonionic polyol polymer, i. e., a hydrophobically modified urethane polymer,
or
combinations thereof. The copolymers are preferably copolymers of a
polycarboxylic
acid monomer and a hydrophobic monomer. The preferred carboxylic acid is
acrylic
acid. The homopolymers and copolymers preferably are crosslinked.
2o Homopolymers of polyacrylic acid are described, for example, in U.S. Pat.
No.
2,798,053, the disclosure of which is hereby incorporated by reference.
Examples of
homopolymers which are useful include Carbopol Registered TM 934, 940, 941,
Ultrez
10, ETD 2050, and 974P polymers, which are available from The B. F. Goodrich
Company. Such polymers are homopolymers of unsaturated, polymerizable
carboxylic
monomers such as acrylic acid, methacrylic acid, malefic acid, itaconic acid,
malefic
anhydride, and the like.
Hydrophobically modified polyacrylic acid polymers are described, for
example, in U.S. Pat. Nos. and 5,349,030, the disclosures of which are herein
incorporated by reference. These polymers have a large water-loving
hydrophilic
portion (the polyacrylic acid portion) and a smaller oil-loving hydrophobic
portion
(which can be derived from a long carbon chain acrylate ester). Representative
higher
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alkyl acrylic esters are decycl acrylate, lauryl acrylate, stearyl acrylate,
behenyl acrylate
and melissyl acrylate, and the corresponding methacrylates. It should be
understood that
more than one carboxylic monomer and more than one acrylate ester or vinyl
ester or
ether or styrenic can be used in the monomer charge. The polymers can be
dispersed in
water and neutralized with base to thicken the aqueous composition, form a
gel, or
emulsify or suspend a deliverable. Useful polymers are sold as Carbopol
Registered TM
1342 and 1382 and Pemulen Registered TM TR-1, TR-2, 1621, and 1622, all
available
from BFGoodrich. Particularly preferred is Pemulen TR-1 (CTFA Designation:
Acrylates/10-30 Alkyl Acrylate Crosspolymer).
l0 Neutralizing agents suitable for use in neutralizing acidic group
containing
hydrophilic gelling agents herein include sodium hydroxide, potassium
hydroxide,
ammonium hydroxide, monoethanolamine, diethanolamine and triethanolamine.
The skin care compositions according to the invention preferably has a pH
which
provides a suitable environment for the keratolytic agent efficacy as well as
to maintain
the skin's moisture balance where the pH is in the range of 4.5 to 6.5.
Preferably, the pH
of the composition ranges from 5.5 to 6.5.
Generally, the water content of the skin care compositions according to the
invention ranges from about 75 to about 85 wt.%, preferably from about 75 to
about 80
wt.% water. This relatively high water content makes the cream light and easy
to apply.
2o The compositions are preferably formulated so as to have a product
viscosity of from
about 75,000 to about 300,000 cps.
The skin care compositions according to the invention can comprise additional
ingredients commonly found in skin care compositions, such as for example,
preservatives, antioxidants, perfumes, chelating agents, etc., provided that
they are
physically and chemically compatible with the other components of the
composition.
Examples of suitable preservatives for use in the skin care compositions of
the invention
include the C~-C4 alkyl parabens and phenoxyethanol. Generally, the
preservative is
present in an amount ranging from about 0.5 to about 2.0, preferably about 1.0
to about
1.5, weight percent based on the total composition. In a preferred embodiment,
the
preservative is mixture of from about 0.2 to about 0.5 weight percent
methylparaben,
from about 0.2 to about 5.0 weight percent propylparaben and from about 0.05
to about
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0.10 weight percent butylparaben. A particularly preferred commercially
available
preservative that may be used in the skin care composition according to this
invention is
PHENONIP TM which is a practically colorless, viscous, liquid mixture of
phenoxyethanol, methylparaben, ethylparaben, propylparaben, and butylparaben
available from Nipa Laboratories, Inc., Wilmington, Del.
Preferably, an oil-soluble antioxidant should be present in the skin care
compositions according to the invention. Suitable antioxidants include
butylated
hydroxy toluene (BHT), ascorbyl palmitate, butylated hydroanisole (BHA),
phenyl-a-
naphthylamine, hydroquinone, propyl gallate, nordihydroquiaretic acid, and
mixtures
1o thereof. Preferably the antioxidant is BHT and is present in the
composition at from about
.02 to about .05wt%, most preferably from about .02 to about 0.10.
Fragrances suitable for use in the skin care compositions according to the
invention
are well known in the art. Particularly preferred are those that can provide a
fruity and/or
floral fragrance, such as, for example, Mod Twist, commercially available from
Haarmann
& Reamer Corp.
In certain aspects of this invention, the compositions should include a
chelating
agent. Chelating agents which are useful in the compositions of the present
invention
include ethylenediamine tetra acetic acid (EDTA) and derivatives and salts
thereof,
dihydroxyethyl glycine, citric acid, tartaric acid, and mixtures thereof. The
chelating
2o agents should be utilized in a stabilizing effective amount and may range
from about
0.01 to about 2% based on the weight of the total composition, preferably from
about
0.05 to about 1 %. Most preferably, the chelating agent should be EDTA.
Other ingredients may include agents which assist in protecting the skin from
aging, such as sunscreens, anti-oxidant vitamins such as ascorbic acid,
vitamin B, biotin,
pantothenic acid, vitamin D, vitamin E and vitamin C, and sodium bisulfate.
Yeast
extract, gingko biloba, bisabolol, panthenol, alpha hydroxy acids and
oligosaccharides
such as melibiose are among other ingredients which assist in preventing aging
of the
skin by such means as irritation mitigation, oxidation mitigation, healing,
affecting
retinoid metabolism and inhibiting the production of elastase.
3o Ingredients with a low comedogenicity capacity should be chosen in order to
render the product non-comedogenic.
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The skin care compositions according to the invention accomplish effective
moisturization through a combination of the softening effects of emollients
with the
moisture retaining action of humectants and coating activities of lubricants,
to counteract
the effect of moisture loss, thereby keeping skin soft, smooth and supple. The
compositions according to the invention have long lasting moisturizing effects
without
the use of occlusive materials.
The compositions of the present invention can be prepared by well-known
mixing or blending procedures. Each phase of the emulsion is preferably
separately
prepared with all of the components contained in the appropriate phase, except
that it is
1 o usually preferred to omit the retinoid compound initially. The emulsion is
then formed
normally by adding the oil phase to the water phase with agitation, and the
emulsion
should be cooled down when the retinoid compound is added. Set forth below is
an
example of a preferred method for preparing the skin care composition
according to the
invention.
Salicylic Acid (premix 1):
In a separate vessel, salicylic acid is added to propylene glycol
and mixed until clear
Phase A (main batch)
1. Purified water is added too mixing vessel.
2. Start side sweep scraper and agitator.
3. EDTA is added and mixed until dispersed.
4. Pemulen TR-1 is sprinkled in and mixed well until
dispersed.
5. The composition is heated to 70-75°C whilst
mixing. At 70-75°C, Carbopol ultrez 10 is sprinkled in and mixed
until dispersed.
6. At 70-75°C, methylparaben is added and mixing is
continued.
7. Glycerin is added and mixing continued.
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8. The composition is held at 70-75°C for phasing.
Phase B (oil phase)
9. Isohexadecane is added to a separate vessel
s followed by cetyl alcohol and heated to 75-80°C, to allow all
ingredients to melt.
10. At approximately 55-65°C, propylparaben is added
followed by butylparaben with mixing after each addition until
well dispersed
l0 11. Butylated hydroxy toluene is added and mixed.
12. Heating is continued to 75-80°C and stearic acid is
added. The composition is allowed to melt and disperse. Stearyl
alcohol is added and then DC 3225C followed by DC 593, and
mixed until uniform.
15 13. Dimethicone is added and all ingredients are well
dispersed.
14. The composition is held at 75-80°C for phasing.
Phasing
20 15. When the oil phase us at 75-80°C and the water
phase is at 70-75°C, the oil phase (phase B) is added to the water
phase (phase A) slowly while homogenizing for 5-10 minutes to
ensure a homogeneous batch.
16. Triethanolamine is slowly added and mixed for 10
25 minutes or until a homogenous batch is achieved.
17. Homogenizer is turned off and the composition is
mixed and cooled to 40-45°C.
18. Salicylic acid is added to the premix
19. Fragrance is added and mixed for 20-25 minutes or
30 until uniform.
20. Viscosity and pH measurement are taken at 25°C.
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The following example is inteded to illustrate the invention without being
limiting in nature.
EXAMPLE
Component CTFA Name Component Trade Name % (w/w)
Water q.s.
Carbomer Carbbopol Ultrez 10 Polymer 0.30
Acrylates/ Coo-3o Alkyl Pemulen TR-1 0.20
Acrylate
Crosspolymer
Disodium EDTA Trilon BD 0.05
Glycerin Pricerine 9073 3.0
Cyclomethicone DC 3225C 2.0
(and)Dimethicone Copolyol
Isohexadecane Isohexadecane 2.0
Dimethicone (and) DC 593 2.0
Trimethylsiloxysilicate
Dimethicone DC 200/350 cst 2.0
Stearyl Alcohol Lanette 18 1.0
Stearic Acid Prisetrine 4900 1.0
Cetyl Alcohol Lanette 16 2.0
Phenoxyethanol & parabensPhenonip 1.0
Propylene Glycol Propylene Glycol USP 3.0
Salicylic Acid Salicylic Acid 0.50
Butylated Hydroxy TolueneBHT 0.02
Triethanolamine Trolamine 1.38
Fragrance ModTwist 0.5
