A NEW SILICONE COMPOSITION FOR BAR SOAP APPLICATIONS
FIELD OF THE INVENTION
The invention relates to silicone additives for bar soaps.
BACKGROUND OF THE INVENTION
Soaps are widely used as skin cleansers, cleaning skin effectively and
economically. However, they are not particularly mild. Soaps irritate skin,
resulting in reddening, roughening and dryness. Therefore, materials which
can counteract the irritating effects of soap, including moisturizers, synthetic
surfactants and silicones are commonly included in the formulation of a soap
bar.
Silicones have long been known to provide a light, silky feel on hair
and skin. However, when silicones are incorporated in bar soaps, they have a
tendency to wash off along with the soap, leaving no silicone residue on the
skin. When silicones are added to bar soaps in the form of fluids, they tend to
become emulsified and the emulsion is washed away with the lather of the
soap. Therefore, even very viscous fluids fail to provide the sensory benefits
of silicones when applied through bar soaps. Compositions containing
silicones also show reduced lather formation.
Surprisingly, it has now been discovered that when a blend of a fatty
alkyl modified silicone, a fatty silicate ester, a high viscosity fluid silicone, a
silicone surfactant and a nonionic/cationic/anionic organic surfactant are
incorporated in a bar soap, enough silicone is deposited on the skin surface to
provide superior sensory benefits while maintaining the lathering and
cleaning properties of the soap. Further, the film deposited is not highly
stable, so an undesirable build up of silicone on the surface over time is
avoided.
The present composition offers the flexibility to incorporate the
silicones using nonionic, cationic and anionic surfactants in bar soap
formulations based on very different oil-based raw materials. The
composition can be used as an emulsion and added to soap noodles or
converted to a granular additive with conventional fillers and added directly
to soap during amalgamation. The practical difficulty of mixing high
viscosity fluids during soap manufacture is therefore overcome.
The use of silicones in cleansing bar compositions has been disclosed in
U.S. Patent No. 5,154,849 to Visscher et al., issued Oct. 13,1992 and in U.S.
Patent No. 5,661,120 to Finucane et al., issued Aug. 26,1997. The silicones
disclosed, however, are difficult to incorporate in a soap bar because of their
high viscosity. The art does not suggest a blend of long chain substituted
silicones and short chain substituted silicones with organic surfactants.
SUMMARY OF THE INVENTION
In one aspect, the invention relates to a composition for improving the
surface deposition of silicones comprising: (a) 0.1 -10 parts of a fatty alkyl
silicone; (b) 0.1 -10 parts of a fatty silicate ester; (c) 30 - 90 parts of a high
viscosity lower alkyl silicone fluid; (d) 0.1 -10 parts of a silicone surfactant; (e)
1-20 parts of an organic surfactant. The organic surfactant comprises one or
more of: (a) a surfactant chosen from the group of nonionic, cationic and
anionic surfactants; (b) a fatty ester sulfonate; (c) sorbitan monostearate; and
(d) sodium lauryl sulfate.
In another aspect, the invention relates to a method for increasing
surface deposition of silicone and improving processing characteristics
comprising adding 0.1-20 parts of the present compositions to 100 parts
soap, whereby silicone deposition is increased substantially while the
cleansing and lathering properties of the soap remain in the acceptable range.
In yet another aspect, the invention relates to a bar soap comprising 0.1
- 20 parts of the present compositions to 100 parts by weight of soap.
DETAILED DESCRIPTION OF THE INVENTION
In its most basic aspect, the invention relates to a method for
improving the surface deposition of silicone and a corresponding composition
for a soap bar additive with improved deposition of silicone on the skin. The
composition comprises: a high viscosity fluid silicone, a fatty alkyl silicone, a
fatty silicate ester, a silicone surfactant, and an organic surfactant.
An essential component of the present compositions is a high viscosity
fluid silicone which is present at a level which is effective to deliver a skin
sensory benefit, for example, from 30 - 90 parts by weight, and preferably
from 58 - 61 parts by weight per 100 parts of a soap additive composition.
High viscosity fluid silicone, as used herein, denotes a silicone with viscosity
ranging from about 5 to about 600,000 centistokes. Silicone fluids useful in
the present invention may be polyalkyl siloxanes, polyaryl siloxanes, or
polyalkylaryl siloxanes of suitable viscosity and molecular weight. The
polyalkyl siloxanes that may be used herein include, for example,
polydimethyl siloxanes. These siloxanes are available, for example, from the
General Electric Company as the Viscasil series. The polyalkylaryl siloxanes
that may be used include, for example, polydimethyphenyl siloxanes and
poly (dimethyl) (diphenyl) siloxanes. These materials are also available from
GE Silicones. The preferred silicone fluids for use in these compositions are
polydimethyl siloxanes with viscosities ranging from about 500 to about
100,000 est.
The organic surfactants useful herein may be selected from cationic,
anionic, and nonionic polymers suitable for contact with human skin. When
used herein, the term 'organic surfactant' refers to a surfactant containing two
or more carbon atoms covalently bonded and not containing any silicon.
These components are generally present from about 1-20 parts per 100 parts
of the additive composition, preferably from about 4.5 parts to 9 parts.
Preferred anionic surfactants for use in the present compositions are sodium
laureth-7 sulfate, sold as Sipon ES-7 by Alcolac and diethylene glycol
monooleate, which may be obtained from Croda Chemical Ltd. as Cithrol
DGMO S/E. Preferred cationic surfactants are dicocodimethylamrnonium
chloride, designated M-Quat-2475 and manufactured by Mazer, and N-(3-
chloroallyl) hexaminium chloride, available as Cosept 200 from Costec, Inc.
Preferred nonionic surfactants are the laurylether polyoxyethylenes sold as
Brij 30 and Brij 35 by ICI India, and higher and lower molecular weight
versions. The sodium salt of a sulfonated fatty ester with hydroxy end groups
is available as Eastman AQ 55 S and is manufactured by Eastman Chemical
Co.
The compositions of the present invention additionally contain a fatty
alkyl silicone and a fatty silicate ester. For the purposes of this invention,
fatty is defined as a branched or straight alkyl chain of from ten to thirty
carbon atoms. An example of a fatty alkyl silicone useful for the present
invention is cetearyl methicone. A preferred fatty silicate ester is diisostearyl
trimethylsiloxy silicate. The fatty alkyl silicone may comprise 0.1 -10 parts by
weight per 100 parts of a soap additive composition, and preferably, about 1
part; the fatty silicate ester may also comprise 0.1 -10 parts by weight per 100
parts of a soap additive composition, and preferably, about 1 part.
Suitable silicone surfactants for use in these compositions may be
obtained from GE Silicones. These may include, for example, a mixture of
cyclomethicone and dimethicone copolyol. The silicone surfactant may be
present in the soap additive composition at 0.1 -10 parts by weight per 100
parts of the soap additive, and preferably, at about 1-9 parts by weight.
The present compositions may optionally include a soap filler. Any of
the standard fillers which are used in the manufacture of soap bars may be
used. An example of a useful filler composition is soap powder/ talc/ treated
silica. A filler may be included in the present compositions at levels from
about 100 -1000 parts by weight per 100 parts soap additive composition, and
preferably 200 - 600 parts.
The soap of the present invention may be any of the widely-known
alkali metal or alkanol ammonium salts of aliphatic alkane or alkene
monocarboxylic acids, prepared by hydrolysis of vegetable oils to
monoglycerides and subsequent saponification of the monoglycerides.
Sodium, potassium, mono-, di-, and tri-ethanol ammonium cations, or
combinations thereof, are typically used. The aliphatic acids generally
contain about 12 to 22 carbon atoms, preferably about 12 to 18 carbon atoms.
They may be described as alkali metal carboxylates of acylic hydrocarbons
having about 12 to about 22 carbon atoms.
Examples
The following non-limiting examples describe the compositions of the
present invention, and the method of making and using them. Soap bars
prepared using these compositions have improved deposition of silicone on
the skin and resulting sensory benefits, while maintaining acceptable
lathering and cleansing properties.
The compositions of the examples in Table 1 were prepared by mixing
the components as listed in the table, and then adding 1 gram of the
composition to 100 grams soap noodles. The soap mixture was blended and
made into soap bars.
The organic surfactant compositions of Examples 10 -13 were prepared
by the following method:
An anionic, cationic, or nonionic surfactant, 38.6 grams, was melted to liquid
form as necessary, and 55.12 grams of a second anionic, cationic, or nonionic
surfactant and 0.55 grams sorbitan monostearate were added. Sodium lauryl
sulfate (0.22 g.) was added to 5.5 grams of a solution of Eastman AQ 55 S in
water (28 grams in 100 ml.) and the resulting solution was added to the
sorbitan monostearate mixture.
For the sample with filler, Example 13, the water was omitted. Instead,
400 grams of a soap powder/ talc/ treated silica filler was added to the
surfactant blend before mixing with the silicone component. This resulted in
a granular material which was easily incorporated in a soap bar.
In order to demonstrate the improved surface deposition of the
compositions of the present invention, soap bars containing the components
listed in Table 1 were prepared. The controls, Examples 2-6, were compared
to soap bars made with various silicone blends and with the compositions of
the present invention. The soaps were evaluated for skin feel and the relative
amount of silicone deposited by each composition, termed % retention, was
determined.
Percent retention was determined by quantitative IR analysis using a
Nicolette FTIR spectrometer. Working standards of cyclomethicone solutions
were prepared in the concentration range of 0.15 mg/g - 26 mg/g. The IR
spectrum of each solution was recorded. A calibration procedure was
developed based on partial least mean square centering. The peak area under
the Si-Me absorption band at 1260 nm was considered for quantification. The
calibration curve was linear throughout the concentration range of the
silicone solutions used. The slope and intercept of the calibration curve
followed an equation for a straight line.
For each experimental composition, a solution of 1 gram soap in 100
grams water was prepared. The solution was applied to a substrate with a
brush and allowed to dry for 20-30 minutes. The quantity applied was
determined by the difference between the weight of the solution bottle plus
the brush before and after the solution was applied. After application and
drying, the site was rinsed with water and the rinse water was collected. The
silicone content of the rinse water was determined from the area under the
peak for the Si-Me absorption at 1260 nm.
The following equation was used for the calculation of % retention:
% Retention = (Silicone applied - Silicone washed off) x 100 / Silicone applied
Results of the Retention analysis appear in Table 2. Retention was less
than 30% for soaps formulated with the silicone controls, and less than 80%
for those made with the organic modified silicones. In contrast, soaps
prepared using the compositions of the present invention had an impressive
surface silicone retention of 93% - 97%.
Skin feel was evaluated subjectively by applying a soap solution using
a brush to a section of the forearm using a standard wash - rinse procedure of
15 soap rubs and 10 water rinses. The compositions of the invention also had
improved skin feel over the controls.
WE CLAIM
1. A composition for improving the surface deposition of silicone comprising:
(a) 0.1-10 parts of a fatty alkyl silicone fluid;
(b) 0.1-10 parts of a fatty silicate ester;
(c) 30-90 parts of a high viscosity lower alkyl silicone fluid;
(d) 0.1-10 parts of a silicone surfactant; and
(e) 1-20 parts an organic surfactant.
2. The composition as claimed in claim 1 wherein said organic surfactant
comprises one or more of:
(a) a surfactant chosen from the group of nonionic, cationic and anionic
surfactants;
(b) a fatty ester sulfonate;
(c) sorbitan monostearate; and
(d) sodium lauryl sulfate.
3. The composition as claimed in claim 2 wherein said surfactant is nonionic.
4. The composition as claimed in claim 2 wherein the surfactant is cationic.
5. The composition as claimed in claim 2 wherein the surfactant is anionic.
6. The composition as claimed In claim 1 further comprising a soap filler.
7. The composition as claimed in claim 1 wherein the fatty alkyl silicone is
cetearyl methicone.
8. The composition as claimed in claim 1 wherein the fatty silicate ester is
diisostearyi trimethylsiloxy silicate.
9. The composition as claimed in claim 1 wherein the viscosity of said lower
alkyl silicone fluid is from about 10,000 est to about 200,000 est.
10. The composition as claimed in claim 1 wherein the high viscosity lower
alkyl silicone fluid is polydimethyl siloxane.
11. A composition as claimed in claim 1 comprising:
(a) cetearyl methicone;
(b) dlisostearyl trim ethylslloxy silicate;
(c) potydimethyl siloxane;
(d) a silicone surfactant; and
(e) an organic surfactant
12. A composition as claimed in claim 1 comprising:
(a) about 1 part cetearyl methicone;
(b) about 1 part dHsostearyl trimethylsiloxy silicate;
(c) 58-61 parts polydimethyl siloxane;
(d) 1-9 parts silicone surfactant; and
(e) 4.5-9 parts of an organic surfactant.
13. The composition as claimed in claim 12 wherein said organic surfactant
comprises:
(a) 250 parts of a higher molecular weight laurylether potyoxyethylene;
(b) 175 parts of a lower molecular weight laurylether polyoxyethylene;
(c) 25-50 parts of a fatty ester sulfonate;
(d) 0-2.5 parts sorbitan monostearate; and
(e) 0-1 part sodium lauryl sulfate.
14.The composition as claimed in claim 12 wherein said organic surfactant
comprises:
(a) 250 parts of dicocodimethylammonium chloride;
(b) 175 parts of N-(3-chloroallyl) hex a minium chloride;
(c) 25-50 parts of a fatty ester sulfonate;
(d) 0-2.5 parts sorbitan monostearate; and
(e) 0-1 part sodium lauryl sulfate.
15.The composition as claimed in claim 12 wherein said organic surfactant
comprises:
(a) 250 parts of sodium laureth-7 sulfate;
(b) 175 parts of diethylene glycol monooleate;
(c) 25-50 parts of a fatty ester sulfonate;
(d) 0-2.5 parts sorbttan monostearate; and
(e) 0-1 part sodium lauryi sulfate.
16.A bar soap composition for improved surface deposition of siiicone
comprising:
(a) a soap;
(b) the composition as claimed in claim 1.
17. A bar soap as claimed in claim 16 comprising
0.1-20 parts of the composition as claimed in claim 1 to 100 parts by weight of
soap.
18.A method for Increasing surface deposition of silicone and improving
processing characteristics of soap comprising adding 0.1-20 parts of the
composition as claimed in claim 1 to 100 parts soap.

A composition for improving the surface deposition of silicone comprising:
0.1-10 parts or a fatty alkyl silicone fluid; 0.1-10 parts of a fatty silicate ester;
30-90 parts of a high viscosity lower alky) silicone fluid; 0.1-10 parts of a
silicone surfactant; and 1-20 parts an organic surfactant.