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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to pigmented cosmetic products in stick, cake, or
cream form such as eyeshadows, foundations, moisturizers, and skin
protecters. More specifically, the invention relates to such cosmetic
products which contain a silicone base, e.g. dimethylpolysiloxane fluid.
This fluid has the chemical formula
##STR1##
wherein both Y substituents are --CH.sub.3, or both are --OH, and in which
the degree of polymerization d is a value, typically between 1 and 150,
effective to give the fluid a viscosity of 0.65 to 1 million centistokes
at 25.degree. C. (Viscosity of such fluids can be measured by widely
recognized test methods, such as the spinning cup test.)
Although dimethylpolysiloxane and other silicone fluids offer the
properties of water repellency, slip, non-greasy emollience, and low
penetration of the skin, their use in anhydrous pigmented cream, cake and
stick products is limited by the difficultly of dispersing inorganic
pigments in the silicone base. The result is that such products contain
only small amounts of pigment, or contain pigment which forms uneven color
streaks in the final product.
It is therefore highly desirable to incorporate inorganic cosmetic pigments
readily into a cosmetic product which contains a silicone fluid or a
mixture of such fluids.
SUMMARY OF THE INVENTION
The invention comprises anhydrous, pigmented cosmetic products comprising a
base of dimethylpolysiloxane having formula (1) above or mixtures of
dimethylpolysiloxane with the organo-polysiloxanes having formula (2), (3)
or (4) given below, or mixtures thereof, in which the pigment is easily
dispersed and remains uniformly distributed without separating or
segregating even at the unusually high pigment contents of 40 to 60 wt. %.
The more dispersible pigment comprises hydrophobic, finely divided
particles of inorganic pigment whose surface is chemically bonded to, and
physically completely coated by, polysiloxane.
By "more dispersible" we mean that by comparison to the same pigment in
uncoated form, the coated pigment is dispersed uniformly throughout the
cosmetic composition more easily and quickly during formulation of the
composition, and it stays dispersed instead of settling or segregating out
of the composition.
DETAILED DESCRIPTION OF THE INVENTION
Cosmetic compositions in accordance with this invention can contain a total
of 10 to 70 wt. % of silicone compounds having formula (1). Alternatively,
the compositions contain 10 to 70 wt. % of a combination of compound (1)
and one or more compounds having formulas (2), (3) or (4), provided that
at least 10 wt. % of the composition is dimethylpolysiloxane of formula
(1). The other silicone compounds, any one, two, or three of which are
included with the dimethylpolysiloxane, can be included in any amount
provided that the total of silicones (1)-(4) is up to about 70 wt. % and
provided that the combination of those compounds is a stable, homogeneous
one-phase mixture at room temperature (25.degree. C.). The preferred range
of the total amount of compounds of formulas (1)-(4) is 20-50 wt. %, in
which case dimethylpolysiloxane comprises at least 20 wt. % of the
composition.
Formula (2) is an organosilane:
RSi(CH.sub.3).sub.3 ( 2)
wherein R is alkyl having 1 to 30 carbon atoms, or aryl.
Formula (3) is an organo-polysiloxane:
##STR2##
wherein R.sub.1 and R.sub.3 are independently alkyl having 1 to 30 carbon
atoms or aryl; X is alkyl or alkyl-oxy and has 1 to 30 carbon atoms;
R.sub.2 is alkyl having 2 to 30 carbon atoms, aryl, or trimethylsiloxy
(CH.sub.3).sub.3 SiO--); R.sub.4 is alkyl having 1 to 30 carbon atoms, or
aryl; n is 1 to 100; m is b 0 to 100; and (n plus m) is 1 to 100.
Formula (4) is cyclomethicone:
##STR3##
As used herein, "alkyl" and the alkyl moities of alkyl-oxy includes
straight- and branched-chain aliphatic groups containing 1 to 30 carbon
atoms; examples include methyl, ethyl, octyl, and octadecyl. Preferred
aryl groups include phenyl and groups in which a phenyl ring is connected
to the Si by an alkyl or alkylene bridge up to 3 carbon atoms long, such
as styryl.
Preferred dimethylpolysiloxanes of formula (1) have a viscosity of about 5
to about 500 centistokes (abbreviated herein as "cs").
Examples of organo-polysiloxanes of formula (3) where m equals zero are
polymethyloctyl-siloxane, polymethyloctadecyl-siloxane,
polyphenyltrimethylsiloxy-siloxane, polymethylphenyl-siloxane, and
octadecyloxydimethylpolydimethyl-siloxane. Examples where n and m are both
non-zero include polymethyl/polymethylphenyl-siloxane,
polymethylstyryl/polymethylethyl-siloxane, and
polymethylstyryl/polymethyldodecyl-siloxane. In this nomenclature, the one
or two substituents named after "poly" are each attached to the silicon
atom in each repeating unit, and substituents before "poly" are attached
to both ends of the polymer chain. To illustrate,
"polymethyloctyl-siloxane" is a compound of formula (3) in which m is
zero, R.sub.1 is methyl, and R.sub.2 is octyl. Furthermore, the term
"polymethylstyryl/polymethyldodecyl-siloxane" means a compound of formula
(3) wherein R.sub.1 is methyl, R.sub.2 is styryl (e.g. C.sub.6 H.sub.5
CH:CH--), R.sub.3 is methyl, and R.sub.4 is dodecyl (e.g. C.sub.12
H.sub.25 --).
The cosmetic composition can also contain 4 to 20 wt. % and preferably 6 to
15 wt. % of a cosmetically acceptable wax; those of ordinary skill in this
art will readily identify what is meant by this term. Examples are
carnauba, ozokerite, glyceryl tribehenate, beeswax, candelilla, paraffin,
bayberry wax, lanolin, micro-crystalline wax, montan, rice wax, mono-, di-
and triglyerol esters of C.sub.12 -C.sub.36 fatty acids, polyethylene,
polyethylene/polyvinyl acetate copolymers, polyethylene/polyacrylic acid
copolymers, C.sub.12 -C.sub.36 fatty alcohols, and C.sub.12 -C.sub.36
fatty alcohol esters of C.sub.12 -C.sub.36 fatty acids, provided that the
wax is solid at room temperature (25.degree. C.). The waxes are further
characterized in that they have crystalline to microcrystalline structure;
leave a film when applied to the skin from a cosmetic stick or cream; have
low viscosity just above their melting points; and exhibit low solubility
at room temperature in the dimethylpolysiloxane described hereinabove.
Typically the waxes are high-molecular-weight hydrocarbons (C.sub.12
-C.sub.100) or mixtures thereof, and esters of high-molecular-weight
(C.sub.12 -C.sub.36) fatty acids with high-molecular-weight (C.sub.12
-C.sub.36) fatty alcohols, and mono-, or di- or triesters of C.sub.12
-C.sub.36 fatty acids with glycerol.
If the cosmetic composition contain wax, it should contain enough of an
organo-polysiloxane of formula (3) described above to provide that the
composition, whether it is a stick, a cake, or a cream, is a single
homogeneous phase. That is, above the melting point of the highest-melting
ingredient one should be able to stir together a molten mixture of the
three components (dimethylpolysiloxane, organo-polysiloxane, and wax)
using conventional mixing equipment; and then, on discontinuing stirring,
the components should not separate into discrete layers or areas of
different composition. Likewise, when a stirred, molten mixture of the
three components is cooled to 25.degree. C., the cooled product should
remain one continuous phase and the wax should not ooze, bleed, or
otherwise separate from the siloxane and/or silane components. In general,
the proper relative amounts of wax and the two silicone components can
readily be determined by examination of the behavior of a sample
formulation; as a general guide to formulations known to be successful,
the weight percentage of the wax can be up to about one-third of the
combined weight percentage of the silicone components, and the weight
ratio of organo-polysiloxane (3) to dimethylpolysiloxane can be up to
about 1:1. Variations from these figures are also contemplated within the
broad aspect of the present invention, however, so long as the proportions
chosen permit the creation of a physically stable one-phase cosmetic
product. Further disclosure regarding this invention is contained in
another application filed on even date herewith entitled "One-Phase
Silicone-Based Cosmetic Product Containing Wax" filled by Marlene Tietjen,
Jane Hollenberg, and Richard Rigg and assigned to the assignee of this
application. The disclosure of that application is hereby incorporated
herein by reference.
The anhydrous cosmetic composition of this invention also contains pigment
which remains uniformly dispersed in the silicone better than has
heretofore been known. The coated pigment is characterized by its complete
hydrophobicity. That is, it is impossible to suspend or disperse even a
very small amount of the coated pigment in water. The coating does not
affect the color; the coated pigment exhibits the same color as the
uncoated pigment. The coating is polysiloxane which is chemically bonded
to the pigment; it is believed to be bonded through oxygen atoms to the
surface of the pigment.
The coated pigment can exhibit structural formula (5)
##STR4##
wherein each of the oxygen atoms at the left end of formula (5) is
attached to an atom P in the pigment surface; and A.sub.1 is an alkyl or
alkenyl group having up to 30 carbon atoms. A number of adjacent
polysiloxane chains as shown in (5) can be cross-linked through oxygen
atoms to form a polysiloxane chain with up to 100 repeating
##STR5##
units that extends along the pigment surface, in addition to the
polysiloxane chain which extends away from the pigment surface. Examples
of alkyl groups are methyl, ethyl, octyl, and octadecyl. "Alkenyl"
includes carbon chains with more than one double bond; examples of alkenyl
groups include ethylene, propylene, acrylyl, and methacrylyl, and residues
of unsaturated fatty acids such as oleic (e.g. C.sub.17 H.sub.33 --),
linoleic (C.sub.17 H.sub.31 --), and linoleNic (C.sub.17 H.sub.29 --).
The coated pigment can also exhibit structural formula (6):
##STR6##
wherein p is 1-100, and P is an atom in the pigment surface.
The coated pigment can also exhibit structural formula (7):
##STR7##
wherein P is an atom in the pigment surface, and in which each of the up
to 100 repeating (Si--O) units is bonded through an oxygen atom to the
pigment surface.
The number of polysiloxane chains of formulas (5), (6) and (7) that are
bonded to the pigment surface is not known but is sufficiently high to
coat the pigment completely and render it completely hydrophobic;
hydrophobicity can readily be determined by placing the coated pigment
into water and observing whether any becomes dispersed or suspended in the
water.
Suitable pigments include all inorganic pigments which are usable in
cosmetic formulations. Particular examples include talc, mica, titanium
dioxide, iron oxide, kaolin, ultramarine, chromium oxide, chromium
hydroxide, zinc oxide, silica, manganese violet, and their equivalents.
The pigment (or a mixture of two or more pigments) can be coated by placing
it in dry, finely divided form in a mixer and adding a silicone material
selected from the group consisting of
(A) A.sub.1 SiX.sub.1 X.sub.2 X.sub.3, wherein A is an alkyl or alkenyl
group having 1 to 30 carbon atoms, and X.sub.1, X.sub.2 and X.sub.3 are
independently chloro, methoxy, or ethoxy (this material will form coated
pigment having formula (5));
##STR8##
wherein p is 1 to 100 and A.sub.2 is hydrogen or an alkyl group having 1
to 30 carbon atoms (this material will form coated pigment having formula
(6));
##STR9##
wherein i is 1 to 100 (this material will form coated pigment having
formula (7)); or a one-phase mixture of two or all three of A, B, and C.
The relative amounts of fluid: pigment should be sufficient to coat the
pigment particles; generally a fluid: pigment weight ratio is satisfactory
for which 1-4 wt. % of the final product is silicone. The pigment and
fluid are intimately mixed thoroughly to obtain a uniform dispersion of
the fluid on the pigment, in which the fluid completely coats the
particles of pigment. The slurrying operation is advantageously carried
out at a temperature of 25.degree. C. to 160.degree. C. effective to
promote hydrolysis and reaction of the silicone with the pigment. As an
alternative to synthesis, satisfactory coated pigments usable in this
invention are sold in a wide variety of shades by Whittaker, Clark &
Daniels, Inc., doing business as Clarks Colors; the product has the trade
name Hydrophobes.
To make the cosmetic composition of the invention, one stirs the
dimethylpolysiloxane component (1) with any other liquid components (such
as silicone component (2), and (3) and/or (4) if liquid at room
temperature) to achieve a uniform mixture. Any of the components which are
initially dry (such as fillers, preservatives, and pigments, including the
coated pigments described herein) are then added to the liquid mixture and
dispersed using high shear equipment (such as a 3-roll mixer or Kady mill)
until a homogeneous dispersion is obtained. This dispersion is then heated
to a point above the melting temperature of the wax material which is to
be added (usually 60.degree.-95.degree. C.). The wax, and any silicone
component which is solid at room temperature, are added and stirred with a
high-shear mixer until all components are melted and dispersed uniformly.
The melted mixture is poured hot (at 60.degree.-95.degree. C.) into the
containers of choice, e.g. pans, jars, or sticks.
The resulting product can be used per se as a cosmetic which is applied to
soothe and moisturize the skin. One can also add optional ingredients such
as cosmetically acceptable fillers, preservatives, and/or fragrance. Dry
ingredients are added in finely divided form to the molten mixture, with
stirring, before the mixture is poured into containers. Examples of
fillers (added alone or in combination) are talc, mica, nylon, silica,
kaolin, zinc oxide, magnesium silicate, calcium silicate, calcium
carbonate, and equivalent materials, added in amounts up to about 35% by
weight of the final product. Another feature of the present invention is
that the filler(s) can also be silicone-coated in the same manner as the
pigments described herein. Examples of preservatives are methyl and propyl
parabens, and equivalents thereof, in amounts up to about 0.5 wt. %. The
cosmetic formulator will recognize that any of the well-known blends of
fragrance oils conventionally sold by fragrance manufacturers can be
added, in amounts generally ranging up to about 0.5 wt %.
The composition can contain up to about 20 wt. % of one or more
cosmetically acceptable oils, to further augment the feel of the product
on the skin and to adjust the product's consistency. Suitable oils are
glycerol esters and C.sub.3 -C.sub.22 alcohol esters of C.sub.3 -C.sub.22
fatty acids, and C.sub.12 -C.sub.22 fatty alcohols, provided that they are
liquid at 25.degree. C. and form homogeneous mixtures with the cosmetic
composition. A preferred example is 2-ethyl-1-hexyl palmitate. The
ordinarily skilled formulator will recognize that other compounds known to
be equivalent to those listed herein can be incorporated to the
composition of this invention.
Utilization of this discovery renders the pigment easily dispersible in the
formulation. The discovery also permits the preparation of products in
which the pigment remains uniformly dispersed without separation. These
properties are particularly advantageous at pigment contents over about 10
wt. % and even more so when the pigment content is over 40 wt. %, e.g.
40-60 wt. %. Satisfactory pigmented products with such high pigment
contents were previously thought impractical or unobtainable because of
the difficulty of dispersing such a high amount of pigment in the oily
base. This development is particularly unexpected in view of the knowledge
that pigments do not disperse well in silicone-based oils. By "pigment" we
mean to include a pigment composition which is made by intimately blending
amounts of two or more other unblended pigments.
Utilization of the coated pigments allows incorporation of more pigment
(generally about 10-20% more) into an anhydrous cosmetic composition than
is otherwise attainable. The higher pigment level provides a smooth, dry
feeling makeup which has excellent slip characteristics due to the
silicone fluid base.
The one-phase, anhydrous, pigmented composition preferably contains 40-60
wt. % of the coated pigment. The balance can comprise the silicone
compounds (1) and (2), (3) and/or (4). Alternatively, the composition can
contain optional cosmetically acceptable filler, fragrance, oil, and/or
wax components. Examples of these components and typically acceptable
amounts thereof are listed above.
The coated pigment and other finely divided solid particles have a size
generally no larger than about 50 microns. It will be recognized that
materials such as mica whose crystalline properties favor formation of
flakes will be finely divided and will be up to about 150 microns in the
long dimension.
The invention is further described in the following Examples.
In each Example, all components that are liquid at 25.degree. C. were mixed
together at room temperature, and then the dry ingredients (preservatives,
fillers, pigments) were mixed into the liquid using high-shear equipment.
When the resulting mixture was homogeneous and all solid components were
uniformly dispersed, the mixture was heated to above the melting point of
the wax so that was about to be added (or above the highest melting point
if more than one wax was added), and then the wax was added and stirred
into the mixture. If the organo-polysiloxane is a solid at 25.degree. C.,
it was added at the same time as the wax. The entire mixture was stirred
using conventional equipment (Lightnin brand mixer or Kady brand mill)
until a uniform mixture was obtained. The mixture was poured hot
(60.degree.-95.degree. C.) into its intended package. No phase separation
or component segregation occurred during or after cooling of the product.
All solid ingredients, including coated pigments, were added in finely
divided form.
A foundation was prepared using this procedure except that the pigments
were not coated with any silicone:
______________________________________
Foundation
______________________________________
Glyceryl tribehenate 6.0
Polymethyloctadecylsiloxane 6.0
2-ethyl-1-hexyl palmitate (oil)
13.0
Dimethylpolysiloxane (10 cs) 25.0
Pigment
Titanium dioxide 17.0
Iron oxide 5.0
Talc 15.0
Mica 13.0 50.0
______________________________________
The melt viscosity of the above formulation was too high to permit it to be
poured into containers. The surface of the product exhibited color
striations and a mottled appearance, which indicated poor dispersion of
the pigment in the product. When the pigment components were provided with
a coating having formula (7) prior to incorporation into the composition,
there resulted a pourable, homogeneous product. The high pigment level
became an advantage rather than a drawback, and provided a smooth, dry
feeling product.
Other examples, which were prepared the same way as above, in which the
pigment was coated prior to addition, were:
______________________________________
Cream Powder Foundation
A B
______________________________________
Glyceryl tribehenate 6.0 10.0
Polymethyloctadecyl siloxane
6.0 --
2-ethyl-1-hexyl palmitate (oil)
13.0 15.0
Dimethylpolysiloxane (10 cs)
25.0 30.0
Pigment*:
Titanium dioxide 20.0 14.5
Iron oxide 7.0 3.0
Talc 13.0 9.5
Mica 10.0 18.0
______________________________________
*The pigment had been coated with polymethyl hydrogen siloxane.
______________________________________
Eyeshadow
______________________________________
Dimethylpolysiloxane 10.0
Glyceryl tribehenate 6.0
Candelilla 2.0
C.sub.12 -C.sub.15 alkyl benzoate ester
7.0
Cyclomethicone D = 5 30.0
Bismuth oxychloride 5.0
Pigment*: 40.0
Chromium oxide 15.0
Ultramarine blue 10.0
Mica 15.0
______________________________________
*The pigment had been coated with methyltrimethoxy silane.
* * * * *
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Description |
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