Note: Descriptions are shown in the official language in which they were submitted.
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LIQUID COMPOSITIONS WHICH THTCKEN ON DILUTION AND METHODS
FOR PRODUCING THE SAME
The present invention relates to liquid cleansing
compositions which have a viscosity which allows them to
readily pour from a bottle or container, but which viscosity
increases during dilution/rinsing. The invention also
relates to a process for lowering level of salt required for
producing dilution thickening effect using associative
thickeners. Compositions comprising such thickeners are
characterized by a cohesive "film°' forming on treated skin
which, in turn, deters rinsability, as measured by a rinse
retention test, and allows for enhanced ease of spreading.
The use of salts to thicken surfactant systems and enhance
viscosity is not new (see Canadian Patent No. 2,211,313).
Typically, a so-called peak viscosity is achieved when salt
is first added, and further addition of salt leads to
viscosity reduction (this is known as over-salting). when
the composition is diluted, the "oversalted" composition
then increases in viscosity once more in a process referred
to as "dilution thickening." .
Dilution thickened compositions typically will form a film
on the skin which lacks cohesion. As such, the film will
dissolve and quickly wash away. As such, the dilution
thickening compositions are generally perceived as readily
rinsable and difficult to spread.
Unexpectedly, the applicants have found that when, in
addition to the level of salt required to form "oVersalted"
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compositions, an associative thickener (e. g.,
hydrophobically modified PEG such as PEG-200 glyceryl
tallowate, such as Rewoderm~ ZIS75 or PEG-7 glyceryl
cocoate) is also used, the film on the skin is far more
cohesive, thereby leading to reduced rinsability and greater
spread on the cleansed surface. This in turn permits
consumer to use less product and offers sensory benefit,
both with and without use of additional applicator/implement
during use.
In addition, the applicants have found the use of
associative thickener lessens the amount of salt needed to
induce dilution thickening.
15 WO 94/16680 to Unilever discloses aqueous dilution
thickening, concentrated liquids comprising 20 o to 60 0
surfactant other than soap or primary alcohol sulphate. The
compositions are said to form a low viscosity, lamellar
phase in the undiluted product and, when diluted, to form
20 into a more viscous rod or hexagonal phase.
Compositions of the subject invention do not require
such high levels of surfactant (i.e., in the '680 reference
it is combination of surfactant and electrolyte which form
initially low viscosity lamellar phase) because, it is
believed, dilution thickening occurs by a different
mechanism, i.e., combination of electrolyte/salt and
hydrophobically modified associative thickener forming a
"film°' which will dilution thicken rather than surfactant
and electrolyte lamellar phase which will dilution thicken.
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Further, there appears to be no disclosure of the
hydrophobically modified associative thickeners of the
invention, or of the effect of such thickeners in lowering
level of salt required for dilution thickening, namely
enhanced rinse retention and ease of spreadability based on
the synergistic combination of the associative thickener and
electrolyte.
Canadian Patent No. 2,211,313 also discloses compositions
which have been oversalted and increase in viscosity upon
dilution.
While there is a broad list of thickeners disclosed (page 9,
third paragraph), there is no disclosure of the specific use
of hydrophobically modified associative polymer, or of its
effect in lowering salt level required to see dilution
thickening effect. Further, there is no disclosure of
enhanced rinse retention based on interaction of the polymer
and electrolyte. There is further no requirement that,.upon
dilution, the composition remain in one phase.
U.S. Patent No. 6,427,177 to Williams et al. entitled "A
Separating Multiphase Personal Wash Compositions in a
Transparent or Translucent Package" discloses a bi-phasic or
multi-phasic liquid in which, in one of the phases, can be
found high levels of electrolyte and an associate thickener.
The compositions of the reference are mufti-phasic before
dilution, and may or may not be mono-phasic upon dilution.
They also require that much higher levels of electrolyte be
used in order to form the biphasic in the first place. By
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_ g _
contrast, the compositions of the subject invention are
single phase compositions prior to dilution.
There is also no disclosure of a process for lowering level
of salt required to obtain dilution thickening effect using
specific associative thickeners.
The applicants have now found a single phase, isotropic,
undiluted compositions comprising:
(1) 5 o to 30 o by wt. of a surfactant or surfactants
for cleansing the skin;
(2) an amount of electrolyte from about 2 o to an
upper level defining a boundary between mono-
phasic and mufti-phasic, said upper boundary
preferably being less than about 9 0, more
preferably 6 o or less;
(3) 0.5 o to 7 0, preferably 1 o to 5 o by wt.
associative thickener;
(4) 0 to 15 o by wt., preferably 1 o to 10 % by wt.
hydrotroping compound; and
(5) 45 o to 95 o by wt. water,
wherein, said composition has viscosity upon dilution, which
is greater than viscosity prior to dilution;
wherein said composition has rinse retention of greater than
o after l0 minutes as measured by tested sample retained
on a test slide as function of rinsing time; and
wherein, upon dilution, said composition remains in a single
phase.
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Isotropic liquids comprising a combination of electrolyte
salt and hydrophobically modified associative thickener have
been found to pour readily out of oontainers, and thicken
upon rinsing. Also, presumably because of a cohesive film
formed on the skin (the applicants do not wish to be bound
by theory in this regard), they both readily spread on and
stay on the skin, as measured in a rinse retention test.
In addition, the applicants have found a process to lower
level of salt required for dilution thickening using
associative thickeners of the invention.
The invention relates to a process for making single phase
dilution thickening compositions comprising electrolyte, By
adding defined associative thickener to said compositions
applicants have found one can lower level of
salt/electrolyte required to obtain dilution thickening
effect. The invention also relates to single phase dilution
thickening compositions both electrolyte and associative
thickener. The two act synergistically to lower level of
salt required for thickening to provide high viscosity
retention and to provide a cohesitivity perceived by
consumers as improved retention.
The invention will now be described by way of example only
with reference to the accompanying drawings, in which:
- Figure 1 describes the effects of varying levels of salt
on dilution thickening compositions without the associative
polymer of the invention. Effects of MgSOq and NaCl on
formulations containing 16o SLES, 3o CAPB, Oo Rewoderm
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ZIS75, and 0% PEG400. As seen, dilution thickening on the
monophasic composition begins at about 5 o salt (by
contrast, when associative polymer of the invention is used,
point of which dilution thickening occurs shifts left or
downwards, i.e., less salt is needed);
- Figure 2 describes the effect of MgS04 salt on the clear,
monophasic compositions of the invention with associative
polymer. Effect of MgS04 concentration neat and diluted
samples of monophasic and biphasic formulations (160 ShES,
3o CAPB, 4o Rewoderm ZIS 75, 110 PEG400). MgS04
concentration labels are of the neat samples. As seen, the
polymer shifts dilution thickening phenomena to 2 o salt in
single phase liquids (by contrast, compositions. of Williams
et al., for example, are biphasic and will presumably have
higher levels of salt);
- Figure 3 describes the effect of associative polymer on
absolute viscosity as a function of dilution ratio (Figure
(a) Dilution thickening effects on formulations of (160 ShES,
3o CAPB, Oo PEG400, 5o MgS04) with and without 4o Rewoderm
ZIS75; (a) absolute viscosities as function of dilution
ratio, (b) percent ratios of diluted to initial viscosities;
- Figure 4 describes the effect of various salts (all at 4
o concentration) on dilution thickening. As seen, some
salts are more effective than others. Effect of salts on
neat and diluted samples of formulations containing 160
SLES, 3o CAPB, 4% Rewoderm ZIS 75,110 PEG400. Salt
concentration was fixed at 40. All samples were monophasic;
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- Figure 5 describes the effect of associative thickener on
dilution thickening. Effect of Rewoderm LIS75 concentration
on formulations with 16o SLES, and 3o CAPB; samples in plot
(a) also contains 4.2o MgS04 and 11o PEG400, samples in (b)
contains 4o MgSOq and Oo PEG400. Figure 5(a) shows effect
with PEG and 5(b) with no PEG; and
- Figure 6 summarizes thickening effect of various
associative thickeners. Effect of thicker types or
formulations with 16o SLES, 3% CAPE, 11o PEG400, and 4.20
MgS04. All thickeners listed were soluble in this
surfactant salt composition. Thickener concentrations are
fixed 4o except for Jaguar C13S and xanthan gum, which were
reduced to to due to the high viscosity of the neat product.
Dilution thickening is generally defined as any diluted
sample having a viscosity greater than that of a neat
product (100:0 product to water). Generally, using
relatively large amounts of salt (e.g., > 5 0) the effect is
achieved. This can be seen, for example, in Figures 1(a)
and 1(b) where formulations comprising surfactants and
varying levels of MgS04 or NaCl show dilution thickening
behavior (at 66:33 dilution) beginning at 5 o salt level.
Previous work (for example in U.S. Patent No. 6,427,177 to
Williams) has been done with so-called biphasic liquids. In
that work, phase separation was seen as a function of both
salt content and content of polyalkylene glycol. At high
levels of polyalkylene glycol (e. g., 11 0), compositions
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g _
were found to be clear, isotropic, one phase solutions at
salt levels of under or about 8 0.
In the present invention it was also found that, when 8 0 or
more salt was used in the undiluted top layer of a biphasic
liquid with no polyalkylene glycol and comprising
associative polymer, the top phase was cloudy, hazy and
opalescent. Since it is desired to have initially clear
liquids, the compositions of the invention generally will
comprise less than 9 o salt, preferably less than 6 o salt.
It should be noted that the only real upper limit is that
there be less electrolyte than the amount which would induce
formation of biphasic since one of the ways in which
compositions of the invention distinguish over Williams is
that they are not biphasic.
Indeed, it is one of the advantages or improvements of the
invention over the prior art that, when using monophasic
liquid compositions it is possible to shift the point at
which the dilution thickening effect of salt is seen from at
least 5 0 (see Figures 1(a) and I(b) to levels of as low as
2 0. This can be seen, for example in Figure 2 where, when
associative polymer and PEG are used, thickening begins as
low as at 2 o salt.
Another benefit of the compositions of the invention is
that, relative to compositions without thickener, the
thickener imparts higher viscosity throughout the dilution
process and maintains the effect of the dilution action.
This is seen in Figure 3.
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_ g _
That is, for example, without thickener at 5 o MgS04, the
absolute viscosity drops sharply after about a 50:50
dilution ratio. With 4 o Rewoderm ZIS75 at the same salt
concentration, dilution thickening is observed up to 40:60
dilution, and the drop off is more gradual. The overall
viscosities of the samples with thickener were also higher.
Plotted as percent ratios between the initial and diluted
viscosities of the samples, Figure 3, the thickener gave
more dilution thickening effect, i.e, the viscosity ratios
are higher with thickener than without. Moreover, after the
drop off in viscosities, diluted samples with thickener
still maintained at least 10 0 of their initial viscosity at
25:75 dilution; without Rewoderm ZIS75, this viscosity ratio
is only 1 o at this dilution.
Finally, another advantage over the art is the "cohesivity"
supplied by the thickener. This is manifested as larger
retention of the dilution thickened shower gel on the skin
and other surfaces (see rinse retention test and results in
examples).
More specifically, the present invention relates to novel,
single phase, isotropic, liquid composition comprising:
(1) 5 % to 30 0, preferably 8 o to 25 o by. wt.
surfactant or surfactants;
(2) from about 2 % electrolyte to an upper level
amount which is both below about 9 o and not high
enough to induce formation of biphasic,
preferably, this is below about 8 0, more
preferably below about 6 o by wt. electrolyte;
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(3) 0.5 o to 7 %, preferably 1 o to 5 o by wt.
hydrophobically modified, preferably although not
necessarily nonionic associative thickener;
(4) 0 to 15 %, preferably 1 o to 20 o by wt.
hydrotroping compound; and
(5) 45 o to 95 o by wt. water,
wherein, said composition has viscosity upon dilution
which is greater than viscosity prior to dilution;
wherein said composition has rinse retention of greater
than 30 o after 10 minutes as measured by a sample
retained on a test slide as a function of rinsing time;
and
wherein, upon dilution, said composition remains in a
single phase.
The invention further relates to a process for lowering
level of salt required to obtain dilution thickening, when
using monophasic liquid composition, by utilizing
associative thickener.
The compositions of the invention should contain 5 o to 30 0
by wt. total composition of one or more anionic, amphoteric
or nonionic surfactant.
Anionic, amphoteric, nonionic surfactant or mixtures thereof
may be used according to the present invention. The anionic
surfactants which are suitable for use according to the
present invention include alkyl sulphates, ether alkyl-
sulphates, alpha olefin sulphonate, sulphosuccinates, soaps,
N-aryl sarcosinates, N-acyl glutamates, N-aryl polypeptide
condensates, aryl isethionates, N-acyl methyl taurates,
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alkyl benzene sulphonates, alcohol sulphates and phosphate
esters among other.
Preferred examples of anionic surfactants are sodium lauryl
sulphate, triethanolamine lauryl sulphate, ammonium lauryl
sulphate, ammonium ether lauryl sulphate, sodium ether
lauryl sulphate, soap, sodium xylene sulphate, sodium
sulphosuccinate, sodium olefin, C14-C16 sulphonate, MEA
disodium cocoamido sulphosuccinate, sodium benzene
sulphonate, sodium cocyl isethionate amongst others.
The anionic surfactant preferably includes an ether alkyl
sulphate of general formula (I):
R-0-(CHI-CH~O)nS03 (I)
wherein
n is 1 to 5 and R is Cg-Clg, preferably C1~.
The amphoteric surfactants which may be used according to
the present invention include alkyl glycinates and
propionates, carboxy glycinates, alkyl betaines, alkyl
imidazolines sulpho betaines, alkyl polyamino carboxylates,
alkyl-amino/iminopropionates and poly ampho carboxy-
glycinates, amongst others. Preferred examples of
amphoteric surfactants are coco-amido-propyl-betaine,
sodium-coco-amphocarboxy-glycinate, coco-amido, sulpho
betaine, coco-ethoxylated MEA, and alkyl-dimethyl-betaine
amongst others.
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The preferred amphoteric surfactants are alkyl-amido-propyl
betaines of general formula (II):
R-C0-NH- ( CH2 ) 3-N+ ( CH3 ) 2-CHI-C00 ( I I )
wherein R has the same meaning as in Formula (I).
It is especially preferred that the alkyl-amido propyl-
betaine is coco-amido-propyl-betaine wherein R is a chain of
coco fatty acid with 12 carbon atoms.
The nonionic surfactants which may be used according to the
present invention include the polyalkoxylated fatty alcohols
and acids and their esters, alkanolamides, polyalkoxylated
and ethoxylated alkanolamides, glycosides and alkyl-
polyglycosides, and long chain ethoxylated amines, alkyl-
amines, amine-oxides, polysorbate, nonoxinols, and
polyoximerts amongst other.
Preferred examples of nonionic surfactants include
polysorbate 20, nonoxinon-l2, polyethylene-24 lauric acid,
coco MEA, and cetyl isooctanoate, amongst others.
A preferred nonionic surfactant is the amino oxides of
general formula (III):
R1R2R3-NO
wherein
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R1 is a C~_~p alkyl group and R~ and R3 are C1_4 chain alkyls.
The typical concentration of surfactant in the compositions
of the present invention lies between 5 o and 30 o by weight
based upon the total weight of the composition, preferably
between 8 o and 25 o by weight, most preferably between 10 0
and 20 o by weight.
.Among the electrolytes (organic and inorganic) which may be
used in accordance with the invention are halides of
alkaline metals, alkaline earth metals, ammonium and other
metals, such as aluminum and zinc; sulphates and phosphates
of alkaline metals, alkaline earth metals, ammonium and
other metals such as aluminum and zinc; MEA and DEA salts,
and alkaline metal silicates, among other.
Preferred examples of electrolytes used according to the
present invention are: sodium chloride, potassium chloride,
sodium sulphate, potassium sulphate, magnesium chloride,
magnesium sulphate, zinc sulphate, ammonium chloride and MEA
chloride among others.
As indicated above, in order to ensure that there is
dilution thickening, there is needed at least about 2 0
salt/electrolyte. However, to ensure, prior to dilution,
the composition is single phase, the salt/electrolyte should
be used in amount below the amount which would cause it to
become biphasic. This depends on the salt and generally
would be expected to be below about 9 0 (again depending on
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whether inclusion will precipitate formation of biphasic),
preferably below about 6 0.
As seen in the examples, the level of salt generally will be
about 2 o to about 6 o although, as noted, the upper limit
is defined in reality only as that amount which will cause
formation of multiphasic from the monophasic state. As also
seen in the examples (Figure 4), particularly preferred
dilution thickening salts include potassium and sodium
chloride. Specifically, Figure 4 shows the viscosities of
the neat and diluted samples containing various salts. At 4
salt, the neat samples containing ZnS04, MgS04, and Na~SOq
appeared most viscous. MgCl2, KCl, and NaCl have little
thickening effect on the initial composition of SZES, CAPB,
PEG400, and Rewoderm LIS75. However, upon dilution, the
monovalence salts I~Cl and NaCl produced tremendous increases
in viscosities to form very viscous gels. ZnS04 and MgS04
were also effective at producing large dilution thickening.
Dilution thickening was observed for all soluble salts at 4
o. Comparatively, at 66:33 dilution, as much as 20 times
increase in the viscosity was observed with NaCl and KC1, 3
to 6 times for MgCl~, MgS04, and ZnSOq, and minor increase
was observed with Na~S04. Effect with Ca012 was not certain
due to its solubility at 4 o in the formulation; CaCl~
appeared insoluble and precipitated.
As seen from Figure 5(a), when various levels of an
associative thickener (e.g., Rewoderm~ ZIS75, tradename of
~14-0~-2005 ~ CA 02534923 2006-02-07 EP0409246
J6B53(C)CT ~'~" '~~ ~vv'' '
- 15 -
PEG-20~? glyceryl tallowate) wEre used (i.e., in e4mpositzon
having 16 o anionic, 3 ~ betaine, Z1 ~ PEG A00 and A.2
MgSOa), there was modest and linear increase in neat sample
single viscosity. Samples diluted to 66:33 had increasing
visCosities Pram 0 to 9 ~ and plateaued at 9 o to 5 %,
Dilution thicY.ening was observed only when at least some
Rewaderm was present (i.e., not at O.D %).
-~'ltC~i~l~''
As also sEen in Figure 5 (b), when~wad not present there
was no viscosity increase in dilut~eGd samples at Q and 1 %,
suggesting that at least about 2 ~ thickener (e. g.,
Rewoderm) may be needed i.n the absence of PEG.
zn gsnexa?, at least 0.5 % thickener is needed, preferably
at least 2 ~.
The associative thickeners (preferably, but not necessarily,
nonionic thickeners) are essentially hydrophobically (e, g.,
tallowate) modified hydrophilic (e. g., water soluble
polyalkylEne glycol) backbone. While not wishing to be
bound by theory, the mechanism tar viscosity enhancement i,s
believed due to inte~:aCtions or associations of the
hydrophobic groups with each other and/or with hydrophobic
coitcponents of the formulations.
Also, because the thickening mechanism is Sndependent of
charge, the pvl3nners ere preferably nonionic and can be used
in high salt environments. Examples of associative
thickeners similar to Rewoderm~ LIS75 are Rheodol~
(tristearate modified PEC) and Elfacos~ T2I2 (carbamic acid
AMENDED SHEET
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- 16 -
diester of the polyoxypropylene, polyoxyethylene ether of
the fatty alcohols derived from palm kernel oil). Other
associative thickeners include ethylene glycol ether of
ethylene cellulose (hydrooxyethyl ethylcellulose) such as
Elfacos~ CD481; or ethyl glycol ether of methyl cellulose,
such as Methocel~ 40-10.
A number of other standard thickeners in personal cleansers
were also tested. Several such as Carbopol~ ETD2020,
Klucel~ HF NF, and Aculyn~ 22 were salt intolerant and
precipitated in the high salt formulations. Jaguar C13S and
xanthan gum were compatible but due to their high molecular
weight and the subsequent high viscosities generated, they
were tested at only 1 0 or less. Figure 6 summarizes the
results for different polymers.
In the neat samples, the polymers have varying thickening
efficiency., Rheodol, Jaguar, and Methocel were highly
effective at thickening the neat samples. Rewoderm~ LIS80
and Varonic~ ZIS80 have similar structures as and behaved
much like Rewoder ~ LTS75. The Table below provides names,
definitions and structures of various polymers which may be
used although it is to be understood that these are for
illustrative purposes and many other polymers may have been
cited.
CA 02534923 2006-02-07
WO 2005/016304 PCT/EP2004/009246
17
N
S N
C V
r1
N
C = Z
U
N
U . z o-
U
V ~ O
O N e--%
N
N U x
CN
U Z S
S Z V'-.p z
N U
O-0 O
N
V ~ N
Z
i ~
U
O=U ti-L
O- S O
S ~
1
1
p O
.
~5 ~ O 7, N
X C
~ > -c3 ~ O ~ _ .
~ ~ 'L ~ a~
_
O N O f6 -F-~ ~ O O _O 'ZS "~
O p ~ O
Q ~ Q O O _O
~ ~
cn N O V s.. U 7, Q O Q) ~ N
~ fU L
-C ~ ~ '~ ~ p) Q. O -~ ~ p O
~, ~ ~ CO ~
O
fn -p S t- >, U U U! _
O ~ O
'S ~ ~ Q) .~ s- v "- O p CCS ~ ~
O ~ ~
U ' ~ ~ U
~ ~'
~
O . p f1 ~
.~ O O ~ . U
0 L ~
~
~
~p~a v O 'ate p-' >'
O~' .
O~
_ ' _
~ ~ ~
~
r ~ ~ O N t4 ~ ~ ~ ~ ~ N
O ~ O ~
L N .~ Q > L O !~ (6 t~ y_ ate, ~ N
L 'a O '~
..C ~ ~ L ~ ~ ~ > _ O O ~, ~ v- v-
~ ~ N U U N O O
> ~
.~... .,-. N +.. tB L L - ~ > L L
p ~ ~ p O 'L~
~ O p O O
O
O _ _ U r
O , ,,
~ -
Qj 'd'
O ~~ _ _ '
~-~ N
~ ~O ~
>~ U p N ~ ?, ~ ?C _ . N
~ ~ O N ' tI) O
> ~ -p
_ L~~p _ _ N O
~~ v UIO ~L~
~L.~ - O
~NO(Ci
_ p ~ O
~ ~ . ~ > >
O ~ N 0
_O Z3 ~ (~ ,N ~ x,. , ,
p = "'. .Q 1.' N V
~
U ~ V
E
~ f
p >' >~p ~ ~ ' N O
~4- O ~ ~ ~.C N
~ ~
~
, ' a n
o ~
p >
c ~ ~ ~ .
s ~ o ~ ~ ~ ~? a
~
M->' C .N ~ _~' >' ~ L '~ p -Q >, ~ ~ 7, 7,
'a U p 4-
O
GsO O ~ ~ >, O O O ~ ~ 'C p O O O ~
?~ ~
~ ~
O d.. U .,- ~ D.. U L I- U Q. v- cfl L11 LL!
> .~ L~ (~ O .,-.
N O
ct3 O t~ fn U
'O cY7
p 'a p ~ O ~ O O p
caO Lt7 O C_n ~
N p T
'
p Cn ~ X .~ ~ (n .. ~ N ,~ '
Cn Cn C D O
~ ~
~
cn~~ ~~ E rY u.W- u.rU~~
~~~~
~
a ~ a~ w
~
c~
O N V ~ ~ ~ >, Q-
~ ~ O
~ _ ~' ~ Q ~ Q
O O
O O O - O
O ~ r X
~ O ~ U
O
-
d ' N l i C T X ~ ?C
CV G O) U I U
L f
~
~ i U' U~ ~ ~ C~ s c'~ ~ a
C~ U .~ ~ . - :~
U .
C9
.Q
~
O O ~
d O ~ ~ ~ 0.. O ~ = =
~ U t W E
n
.~
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- 18 -
As seen in Figure 6, at 6:33 dilution, the polymers that
clearly exhibited dilution thickening behavior were Rewoderm
hIS75 and ZIS80, Elfacos T212 and CD481, Rheodol, Varonic
hIS80, and Methocel 40-100. The Acrysol RM825 appeared to
maintain or even slightly increase viscosity. The non-
hydrophobically modified polymers (Jaguar C13S and xanthan
gum) did not thicken upon dilution. It can be seen that the
associative nature of the polymers aids in the dilution
thickening phenomenon.
In addition to the ingredients noted above, the compositions
of the invention may contain hydrotropes including but not
limited to short chain monohydric or dihydric alcohols,
xylene sulphonate and hexylene glycol whose purpose is to
avoid the formation of liquid crystal phases resulting from
the separation of the surfactant material into the upper
phase and hence increasing its apparent concentration.
As noted above, while salt is required for dilution
thickening, use of associative polymer with salt provides
synergistic advantages. First, it shifts lower the level of
salt required before the effect can occur (e.g., to 2 0
rather than 5 o). Second, rheologically, it imparts higher
viscosity throughout the dilution process and maintains the
effect of higher dilution ratio (Figure 3). Finally, as
noted in examples, the combination leads to enhanced rinse
retention.
In addition to the ingredients noted above, the compositions
of the invention may contain a variety of optional
ingredients such as set forth below:
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The compositions may comprise benefit agents. Benefit agent
may be any material that has potential to provide an effect
on, for example, the skin.
The benefit agent may be water insoluble material that can
protect, moisturize or condition the skin upon deposition
from compositions of invention. These may include silicon
oils and gums, fats and oils, waxes, hydrocarbons (e. g.,
petrolatum), higher fatty acids and esters, vitamins,
sunscreens. They may include any of the agents, for
example, mentioned at column 8, line 31 to column 9, line 13
of U.S. Patent No. 5,759,969, hereby incorporated by
reference into the subject application.
The benefit agent may also be a water soluble material such
as glycerin, enzyme and a- or ~S-hydroxy acid either alone or
entrapped in an oily benefit agent.
The benefit agent may be found in either the upper or the
lower layer depending on its solubility and partition
coefficient, for example, oil may partition into the upper
layer while more water soluble agents (e. g., a-hydroxyacids)
may go into the lower.
The compositions may comprise perfumes, sequestering agents
such as EDTA or EHDP in amounts 0.01 o to 1 0, preferably
0.01 o to 0.05 0; coloring agents, opacifiers and pearlizers
such as zinc stearate, magnesium stearate, Ti02, EGMS
(ethylene glycol monostearate) or styrene/acrylate
copolymers.
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The compositions may further comprise antimicrobials such as
2-hydroxy 4,2'4' trichlorodiphenylether (DP300), 3,4,4'-
trichlorocarbanilide, essential oils and preservatives such
as dimethyl hydantoin (Glydant XZ 1000), parabens, sorbic
acid etc.
The compositions may also comprise coconut aryl mono- or
diethanol amides as suds boosters, and strongly ionizing
salts such as sodium chloride and sodium sulfate may also be
used to advantage.
Antioxidants such as, for example, butylated hydroxytoluene
(BHT) may be used advantageously in amounts of about 0.010
or higher if appropriate.
Cationic conditioners which may be used including Quatrisoft
ZM-200 Polyquaternium-24, Merquat Plus 3330- Polyquaternium
39: and Jaguar~ type conditioners.
Examples
Except in the operating and comparative examples, or where
otherwise explicitly indicated, all numbers in this
description indicating amounts or ratios of materials or
conditions or reaction, physical properties of materials
and/or use are to be understood as modified by the word
"about".
Where used in the specification, the term "comprising" is
intended to include the presence of stated features,
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integers, steps, components, but not to preclude the
presence or addition of one or more features, integers,
steps, components or groups thereof.
The following examples are intended to further illustrate
the invention and are not intended to limit the invention in
any way.
Unless indicated otherwise, all percentages are intended to
be percentages by weight.
In addition to composition elements, it is critical that
compositions of the invention meet the following
requirements.
First, they are dilution thickening, by which is meant that
the composition, upon dilution, has viscosity greater than
that prior to dilution.
Second, they must have rinse retention defined by retention
of greater than 30 o by weight, after 10 minutes of
soaking/rinsing in water, as measured by amount of sample
retained on a test slide as function of rinsing time.
Third, the composition must be single phase before dilution.
Methodology
n,.. rrt-,a-r"..~
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Trade Name
i
Sodium Laureth Ether Sulfate (69%Genapol LRO SLES
actives) ISLES)
Coco Amido Propyl Betaine (30% Dehyton K CAPE
to 39%
actives) (CAPB)
Salts (MgS04, NaCI, KCI, MgCl2,
CaCl2,
Na2S04, ZnS04)
Poly(efihylene glycol) (400 EO's)PEG400
,
Formulation Preparation
A 75 o concentrated surfactant base was first prepared with
SZES, CAPB, and perfume. The 25 o hole or deficit was
reserved for later addition of water, thickener and salt.
The final composition contained 16 o SLES, 3 o CAPB and 1 0
perfume.
Base Formulation Preparation
Preparation was as follows:
1) Using jacketed beaker and water bath, water was heated
to 65°C and mixing started with overhead stirrer.
2) SLES was added to water.
3) The formulation was checked for clumps which were
broken as required.
4) The temperature was lowered and CAPB was added.
5) The composition was cooled to room temperature and
perfume was added.
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Full Formulation Preparation
Subsequent addition of thickener, polyethylene glycol, and
salt to the concentrated base above was done at room
temperature using an overhead mixer until homogenized. For
example, to prepare formulation with 16 o SLES, 3 % CAPB, 1
o perfume and 1 o thickener, 1 g of thickener (assuming 100
o active) and 24 g of water was added to 75 g of above base.
Likewise to prepare formulation with 16 o SLES, 3 o CAPB, 1
o perfume and 9 o MgS04-anhydrous, 17g MgS04-7H~0 and 8 g of
water were added.
A typical formulation of the invention is as follows:
Ingredient % by wt.
~
Sodium lauryl efiher sulfate ISLES)16
Rewoderm LIS75 4
Cocoamidopropyl befiaine (CAPB) 3
PEG 400 19
MgS04 4
Perfume 1
Water Balance
Rheoloav Measurement
Rheology measurements were conducted using a controlled
strain rheometer (Rheometric Scientific ARES) primarily. A
Haake viscometer was used intermittently for quick checks of
prototypes. All data reported here were measured using ARES
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rheometer with the cone and plate or Couette geometry at
25°C. The shear rate sweeps were run in logarithmic mode
from 0.1 to 1000 s-1, with 5 points per decade. Viscosities
are quoted for a fixed shear rate at 10 s 1.
For dilution data, viscosity measurements were conducted on
equilibrated samples. The formulations were first mixed
with deionized water at appropriate ratios by weight, using
magnetic stir bars or wrist shaker, and allowed to
equilibrate for 4 hours to overnight, all at room
temperature. Shear sweeps were then done as described
above.
Example 1
In order to show the dilution thickening effect and amount
of salt normally needed to cause the effect, the applicants
prepared compositions s follows:
SLES 16 0
CAPB 3 0
Thickener 0
PEG 400 0
Levels of salt (MgS04 and NaCl) varied from 0 to 9 % and
viscosities were tested both neat (100:0) and at dilution of
66:33. Results are set forth in Figures 1(a) and 1(b).
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As discussed in the specification above, when no polymeric
thickener is used, the diluted thickening effect is not seen
until 5 o salt is used.
By contrast, the applicants tested compositions having
formulation as follows:
SLES 16 0
CAPB 3 0
Rewoderm (LIS75) 4 0
PEG 400 11
Results under varying levels of MgS04 are seen in Figure 2.
With thickener, it can be seen that level of salt to induce
dilution thickening is as low as 2 0. Thus, this thickener
clearly induces a shift.
Example 2
In order to show difference in dilution behavior of salts
with or without thickener, the applicants tested the
following formulation:
SLES 16 0
CAPB 3 a
PEG 400 0
MgS04 5 0
Rewoderm LIS75 4 0 or 0
The results are set forth in Figures 3a and 3b.
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As can be clearly seen, rheologically the thickener imparts
higher viscosity increases throughout the dilution process
and maintains the effect of higher dilution. Specifically
without thickener at 5 o MgS04, the absolute viscosity drops
sharply after about a 50:50 dilution ratio. With 4 0
Rewoderm LIS75 at the same salt concentration, dilution
thickening is observed up to 40:60 dilution, and the drop
off is more gradual. The overall viscosities of the samples
with thickener were also higher.
Plotted as percent ratios between the initial and diluted
viscosities of the samples, Figure 3b, the thickener gave
more dilution thickening effect, i.e. the viscosity ratios
are higher with thickener than without. Moreover, after the
drop off in viscosities, diluted samples with thickener
still maintained at least 10 0 of their initial viscosity at
25:75 dilution; without Rewoderm LIS75, this viscosity ratio
is only 1 o at this dilution.
Example 3
In order to show effect of salt concentration and type,
applicants tested the following compositions:
SLES 16 a
CAPB 3 0
Rewoderm LIS75 4 0
PEG 400 11 0
Salt (Varying) 4 0
Results are set forth in Figure 4.
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Figure 4 shows the viscosities of the neat and diluted
samples containing various salts. At 4 o salt, the neat
samples containing ZnS04, MgS04, and Na~S04 appeared most
viscous. MgCl~, KCl, and NaCl have little thickening effect
on the initial composition of SZES, CAPB, PEG400, and
Rewoderm Z,IS75. However, upon dilution, the monovalence
salts KCl and NaCl produced tremendous increases in
viscosities to form very viscous gels. ZnSOq and MgS04 were
also effective at producing large dilution thickening.
Dilution thickening is observed for all soluble salts at 4
o. Comparatively, at 66:33 dilution, as much as 20 times
increase in the viscosity is observed with NaCl and KC1, 3
to 6 times for MgCl~, MgS04, and ZnS04, and minor increase
was observed with Na2SOq, Effect with CaCl2 was not certain
due to its solubility at 4 o in the formulation; CaCl2
appeared insoluble and precipitated.
Example 4
In order to show the effect of varying concentration of
associative thickener, the applicants tested the following
compositions:
SZES 16 0
CAPB 3 0
PEG 11 0 or 0
MgS04 4.0 0 or 4,2 0
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Rewoderm LIS75 Varying
The results are set forth in Figure 5. As seen in Figure
5(a), as the amount of thickener increases in composition
without PEG, there is a modest linear increase in viscosity
of the neat sample. The viscosities increase at 0 to 4 0
and plateau between 4 o and 6 0.
With 4.2 o MgS04 and 11 o PEG400, dilution thickening was
observed only when Rewoderm LIS75 was present. Similar
effect was observed in formulations without PEG400. Figure
5(b) shows the trends for compositions with 4 o MgS04, 0 0
PEG400, and 0 to 4 o Rewoderm LIS75. In the absence of
hydrotropic PEG, the high viscosities of the neat samples
come mostly from the salt (MgS04) and the thickener appeared
to contribute little effect. Comparing the neat samples, 0 0
Rewoderm LTS75 has a viscosity of 21,500 centipoises, while
those containing 1 o to 4 o Rewoderm LIS75 have viscosities
between 11,500 and 21,700 centipoises. Method given under
Rheology Measurement: ARES or Haake rheometer, shear rate of
10 s I, 25°C .
In the diluted samples, the viscosity increase was not
observed at 0 and 1 o Rewoderm LIS75. Dilution thickening
was significant at 2 o Rewoderm LIS75 and modest at 3 o and
4 o Rewoderm ZIS75. This suggests that at 4 o MgS04, with
and without PEG400, Rewoderm LIS75 concentration at greater
than 1 o is required for dilution thickening.
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Example 5
In order to show dilution thickening effect of various
thickener types, the applicants tested the following
formulations.
SLES 16 0
CAPB 3 0
PEG 400 11
MgS04 4.2 0
Thickener 4 a*
* except Jaguar CI3S and Xanthan gum, which were reduced to
1 o due to high viscosity of the neat product.
The results were set forth in Figure 6. As seen, in the
neat samples, the polymers have varying thickening
efficiency. Rheodol, Jaguar, and Methocel are highly
effective at thickening the neat samples. Rewoderm LIS80
and Varonic LIS80 have similar structures as, and behaved
much like, Rewoderm LIS75.
At 66:33 dilution, the polymers that clearly exhibited
dilution thickening behavior were Rewoderm LIS75 and LIS80,
Elfacos T212 and CD481, Rheodol, Varonic LIS80, and Methocel
40-100. The Acrysol RM825 appeared to maintain or even
slightly increase viscosity. The non-hydrophobically
modified polymers (Jaguar C13S and xanthan gum) did not
thicken upon dilution. It appeared that the associative
nature of the polymers aid in the dilution thickening
phenomenon.
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Example 6 - Rinse Retention
The enhanced retention of the dilution thickening effect was
clearly observed during a handwash with the samples.
Samples containing the associative thickener of the
invention formed a sticky film on skin that persisted for a
long time during the rinsing, whereas the samples with only
salts rinsed off more quickly. This retention effect was
quantified by simulating the gel application and rinsing
process. The method was set up to capture the retention
effect as a function of time. The procedure is illustrated
as follows:
1) Mark a 3 inch x 2.5 inch area on a glass microscope
slide
2) Record weight of microscope slide
3) Plaee approximately 0.5 g of sample on the slide,
spread evenly to cover the marked area, and record
weight of slide and sample
4) Fill a 2 oz jar with 50 g deionized water and place a
magnetic stir bar at the bottom of the jar
5) Place the slide in the water jar such that the sample
area is completely submerged under water and the slide
is not touching either walls, bottom of jar, or stir
bar.
6) Agitate water in the jar using a magnetic stirrer on at
a speed setting four
7) Remove slide from jar at set time intervals (5 minutes,
10 minutes, 30 minutes, 60 minutes, and 2 hours), and
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remove excess water from slide, but not touching the
sample area using Kimwipes
8) Record weight of sample and slide
9) Return sample to water jar to same position as in step
(5)
10) Repeat steps (5) to (8) for the remaining time
intervals, or until no sample residue is left on slide.
Table 1 below lists results for the samples tested. The
samples each contained 16 o ShES, 3 o CAPB, and 0.0125 0 of
a water soluble blue dye (Acid Blue 9 or Erioglaucine
disodium salt); the amount of salt, thickener, and PEG400
were varied; all these compositions were clear isotropic
monophasic. Rinse retention was calculated as a percent of
the sample remaining on the slide after ~~rinsing", or
submerged in the stirred water, for fixed amounts of time.
Although excess water on the slides was dried off before
weighing, any water absorbed by the samples was not removed.
Hence, some of the percentages can be greater than 100 0
(e. g. sample 6B).
In all samples where no thickeners were added, the samples
mostly rinsed off by 5 minutes of stirring; trace amounts
remained on the slides after 10 minutes, and the slides were
completely cleaned by 30 minutes. TiJhen thickener was used,
about half the samples were still retained after 10 minutes of
rinsing; significant amounts were still visibly stuck on after
minutes, and most samples rinsed off between 1 to 2 hours
of soaking and stirring. Comparing 1 o and 4 o Rewoderm hIS75
30 levels (although the salt concentrations differed), the higher
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thickener levels prolonged the retention of the samples during
rinsing. Also, PEG400 did not affect the retention trend.
Table 1: Compositions and results for gel retention test
'~~ Composition Percent
Sample (16 or'
% sample
SLES, retained
3 on slide
% as function
CAPB, of
+) "rinsing"
time
MgS04 Rewoderm PEG40 5 10 30 60 120
LIS75 0 minutes minutesminutesminutesminutes
6A 4% 0% 0% 28% 3% 0%
6B 4% 4% 0% 113% 102% 33% 21 % 3%
6C 4% 4% 11 % 85% 57% 18% 0%
6D 4% 0% 11 % 43% 3% 0%
6E 6% 0% 0% 22% 5% 0%
6F 6% 1% 0% 47% 36% 14% 8% 2%
