Note: Descriptions are shown in the official language in which they were submitted.
WO94/29415 PCT~S94/06117
2~ 6481~
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STABLE AQUEOUs EMULSIONS OF NONIONIC SURFACTANTS
Technical field
The present invention relates to cleaning compositions.
More particularly, the cleaning compositions according to the
present invention are stable aqueous emulsions of nonionic
surfactants particularly suitable for the pretreatment of
laundry or the cleaning of hard surfaces.
8ackqround
A great variety of cleaning compositions have been described
in the art. For instance, in co-pending European Patent
Application EP 92870188.7, a particular type of cleaning
compositions is described which are aqueous emulsions of a
nonionic surfactant system. Such emulsions find a preferred
application in the formulation of bleaching compositions
comprising hydrogen peroxide or water soluble source thereof
and a liquid hydrophobic bleach activator, or any other
hydrophobic ingredient which needs to be separated from
hydrogen peroxide. Alternatively, such emulsions can be used
to formulate products which do not contain hydrogen peroxide.
In the latter case, such emulsions can be useful because they
WO94/29415 PCT~S94/06117
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allow to keep a given hydrophobic ingredient separate from
the aqueous phase, with which said hydrophobic ingredient
could react, e.g., by hydrolysis. Another advantage of such
emulsions is that they provide a means to formulate
ingredients with very low water solubility, without the need
for using alcoholic or solvent mixtures, which are usually
undesirable for aesthetic (odour) and toxicity reasons.
A problem with such emulsions, especially with emulsions
containing relatively high concentrations of surfactants,
e.g, about 8 %, is that important viscosity tends to build
up, which makes said emulsions difficult to dispense, and
thus unacceptable from a consumer viewpoint.
It is thus an object of the present invention to formulate
aqueous emulsions of nonionic surfactants wherein the
viscosity can be conveniently controlled.
Various viscosity agents such as sodium cumene sulphonate and
polyacrylates have been tried in this context, which resulted
in a decreased viscosity but also reduced phase stability.
It is thus another object of the present invention to provide
aqueous emulsions of nonionic surfactants wherein the
viscosity can be conveniently contrnlled while maintaining
adequate physical stability.
In order to manufacture such aqueous emulsions of nonionic
surfactants, it is necessary to vigorously mix the
ingredients together. During this vigorous mixing, lots of
air bubbles are generated which are detrimental both to the
composition's aesthetics and stability. Indeed, surfactants
tend to concentrate at the air/liquid interfaces generated by
said air bubbles. Thus the more air bubbles a composition
contains, the less surfactants will be available for the
stabilisation of the droplets of the dispersed phase. This
problem of air bubbles is aggravated in that aqueous
WO94/29415 PCT~S94/06117
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emulsions of nonionic surfactants are pseudoplastic fluids,
i.e. they have a higher viscosity at low shear rates.
Consequently, the air bubbles generated upon mixing, i.e. at
low viscosity become entrapped in the compositions when
miXing stops and viscosity consequently raises. For the same
reasons, air bubbles tend to become entrapped in the
compositions also when the product is pulled from the bottle
into another container, i.e. a dosing device, or when the
bottle is shaken.
It is thus another object of the present invention to provide
aqueous emulsions of nonionic surfactants which are
substantially free of air bubbles and thus acceptable for
aesthetics and stability.
It has now been found that these objects can be efficiently
met by formulating aqueous emulsions of nonionic surfactants
which comprise silicone compounds. In other words, it has
now been found that silicone compounds reduce the viscosity
of aqueous emulsions comprising a nonionic surfactant system
whatever the viscosity was before their addition and allow to
substantially eliminate the air bubbles. Additionally, it
has unexpectedly been found that emulsions comprising
silicone compounds are physically more stable than emulsions
without said silicone compounds.
The present invention allows for greater flexibility in
formulating and provides stable aqueous emulsions suitable to
be used in the most efficient manner by the consumer.
The viscosity-reducing effect and the air bubbles removal
properties of the silicone compounds are unexpected and
beneficial as said silicone compounds are only known in the
context of laundry compositions as sud-suppressing agents,
see for instance US 4 076 648, US 4 021 365, US 4 749 740, US
4 983 316, EP 150 872, EP 217 501 and EP 499 364.
W094/29415 PCT~S94/06117
~ 16 ~8 iS 4
As an additional advantage it has been found that the present
invention finds a preferred application in formulating
aqueous activated bleaching emulsions and bleaching emulsions
which comprise any hydrophobic liquid ingredient which needs
to be kept separate from the hydrogen peroxide. Indeed, the
addition of silicone compounds accordi-ng to the present
invention to the nonionic surfactant system used to emulsify
hydrophobic liquid ingredients as for instance bleach
activators improves the storage stability of hydrogen
peroxide.
Summary of the invention
The present invention is a stable aqueous emulsion having a
pH of from 0.5 to 6, comprising a hydrophilic nonionic
surfactant and a hydrophobic nonionic surfactant, said stable
aqueous emulsion further comprises an effective amount of
silicone compounds.
Detailed descri~tion of the invention
The compositions according to the present invention are
stable aqueous emulsions of nonionic surfactants. By stable
emulsion it is meant an emulsion which does not substantially
separate into distinct layers, upon standing for at least 2
weeks at 50 C.
The compositions according to the present invention are
aqueous. Accordingly, the compositions according to the
present invention comprise from 10% to 95% by weight of the
total composition of water, preferably from 30% to 90%, most
preferably from 60% to 80%. Deionized water is preferably
used.
W094ng415 S PCT~S94/06117
_ 5 ~ 81 5
The compositions according to the present invention are
emulsions of nonionic surfactants. Said emulsions of
nonionic surfactants comprise at least two nonionic
surfactants. Said two nonionic surfactants in order to form
emulsions which are stable must have different HLB values
(hydrophilic lipophilic balance), and preferably the
difference in value of the HLBs of said two surfactants is at
least 1, preferably at least 3. By appropriately combining
at least two of said nonionic surfactants with different HLBs
in water, emulsions according to the present invention will
be formed.
one of said nonionic surfactants used herein is a nonionic
surfactant with an HLB above ll (herein referred to as
hydrophilic nonionic surfactant), whereas the other one is a
nonionic surfactant with an HLB below 10 (herein referred to
as hydrophobic nonionic surfactant).
Suitable nonionic surfactants for use herein include
alkoxylated fatty alcohols. Indeed, a great variety of such
alkoxylated fatty alcohols are commercially available which
have very different HLB values. The HLB values of such
alkoxylated nonionic surfactants depend essentially on the
chain length of the fatty alcohol, the nature of the
alkoxylation and the degree of alkoxylation. Hydrophilic
nonionic surfactants tend to have a high degree of
alkoxylation and a short chain fatty alcohol, while
hydrophobic surfactants tend to have a low degree of
alkoxylation and a long chain fatty alcohol. Surfactants
catalogues are available which list a number of surfactants
including nonionics, together with their respective HLB
values.
The compositions according to the present invention comprise
from 2 % to 50 % by weight of the total composition of said
hydrophilic and hydrophobic nonionic surfactants, preferably
from 5 % to 40 %, most preferably from 8 % to 30%.
W094/29415 ~16 ~ 815 PCT~S94/06117
The compositions according to the present invention may
further comprise other nonionic surfactants which should
however not significantly alter the weighted average HLB
value of the overall composition.
The compositions according to the present invention further
comprise as an essential element an effective amount of
silicone compounds. By "effective amount" it is meant an
amount of silicone compounds which is sufficient to reduce
and substantially eliminate the air bubbles generated in the
aqueous emulsions according to the present invention. By
"effective amount" it is also meant an amount of silicone
compounds which is sufficient to provide physically stable
aqueous emulsions wherein the viscosity can be conveniently
controlled. Preferably the compositions according to the
present invention comprise from O.Ol % to 5 % by weight of
the total composition of said silicone compounds, more
preferably from O.l % to 2 %.
Said silicone compounds reduce the viscosity of the aqueous
emulsions herein whatever the viscosity was before the
addition of said silicone compounds while increasing also
physical stability. Preferred compositions obtained
according to the present invention have a viscosity of from
lO0 cps to 3000 cps at 50 rpm shear rate at 25 C, more
preferably from 300 cps to 1500 cps, measured by a Brookfield
DV II rotational viscosimeter.
Additionally, said silicone compounds substantially reduce
and preferably substantially eliminate the air bubbles
generated either during the manufacture of said emulsions or
when pouring or shaking said emulsions, thereby providing
aqueous emulsions which are acceptable for aesthetics and
stability.
In industrial practice, the term "silicone" has become a
generic term which encompasses a variety of relatively high-
WO94/29415 2 ~ 6 ~ 81 5 PCT~S94/06117
molecular-weight polymers containing siloxane units and
hydrocarbyl groups of various types. Indeed, silicone
compounds have been extensively described in the art, see for
instance US 4 076 648, US 4 021 365, US 4 749 740, US 4 983
316, EP 150 872, EP 217 501 and EP 499 364. The silicone
compounds disclosed therein are suitable in the context of
the present invention. Generally, the silicone compounds can
be described as siloxanes having the general structure :
~~(~Si~)n~~
I
R
wherein n is from 20 to 2.000, and where each R independently
can be an alkyl or an aryl radical. Examples of such
substituents are methyl, ethyl, propyl, isobutyl, and phenyl.
Preferred polydiorganosiloxanes are polydimethylsiloxanes
having trimethylsilyl endblocking units and having a
viscosity at 25C of from 5 x 10-5 m2/s to 0.1 m2/s i.e. a
value of n in the range 40 to 1500. These are preferred
because of their ready availability..and their relatively low
cost.
A preferred type of silicone compounds useful in the
compositions herein comprises a mixture of an alkylated
siloxane of the type hereinabove disclosed and solid silica.
The solid silica can be a fumed silica, a precipitated silica
or a silica made by the gelformation technique. The silica
particles can be rendered hydrophobic by treating them with
diaklylsilyl groups and/or trialkylsilane groups either
bonded directly onto the silica or by means of silicone
resin. A preferred silicone compound comprises a hydrophobic
W094~9415S~1~ 4 8 1~ PCT~S94/06117
silanated, most preferably trimethylsilanated silica having a
particle size in the range from 10 mm to 20 mm and a specific
surface area above 50 m2/g. Silicone compounds employed in
the compositions according to the present invention suitably
have an amount of silica in the range of 1 to 30% (more
preferably 2.0 to 15%) by weight of the total weight of the
silicone compounds resulting in silicone compounds having an
average viscosity in the range of from 2 x 10~4m2/s to lm2/s.
Preferred silicone compounds may have a viscosity in the
range of from 5 x 10~3m2/s to O.1m2/s. Particularly suitable
are silicone compounds with a viscosity of 2 x 10~2m2/s or
4.5 x 10~2m2/s.
Suitable silicone compounds for use herein are commercially
available from various companies including Rhone Poulenc,
Fueller and Dow Corning. An example of silicone compounds
for use herein is Silicone DB R 100 commercially available
from Dow Corning.
Formulating the compositions according to the present
invention in an acidic pH range contributes to the stability
of the composition. The compositions of the present
invention have a pH as is of from 0.5 to 6, preferably of
from 1 to 5. The pH of the composition can be trimmed by
all means available to the man skilled in the art.
Preferred compositions according to the present invention
comprise hydrogen peroxide or a water-soluble source thereof.
Suitable water-soluble sources of hydrogen peroxide include
perborate, percarbonate, persilicate and persulphate salts.
Hydrogen peroxide is most preferred to be used in the
compositions according to the present invention. Typically,
the compositions according to the present invention comprise
from 0.5% to 20% by weight of the total composition of
hydrogen peroxide, preferably from 2% to 15%, most preferably
from 3% to 10%.
W094n9415 2 ~ G ~ 81 S PCT~S94/06117
Preferred compositions according to the present invention
further comprise a bleach activator. By bleach activator, it
is meant herein any compound which reacts with hydrogen
peroxide to form a peracid. In the case of bleach
activators, such hydrophobic bleach activators typically
belong to the class of esters, amides, imides, or anhydrides.
A particular family of bleach activators of interest in the
present invention were disclosed in applicant's co-pending
European patent application No 91870207.7. Particularly
preferred in that family is acetyl triethyl citrate which was
also disclosed in the context of bar soaps in FR 2 362 210.
Acetyl triethyl citrate has the advantages that it is
environmentally friendly as it eventually degrades into
citric acid and alcohol. Furthermore, acetyl triethyl
citrate has a good hydrolytical stability in the product upon
storage and it is an efficient bleach activator. As used
herein and unless otherwise specified, the term bleach
activator includes mixtures of bleach activators.
In a preferred embodiment of the present invention, wherein
the compositions comprise a bleach activator which is a
hydrophobic liquid ingredient, the nonionic surfactant system
to be chosen to emulsify said bleach activator depends on the
HLB value of said bleach activator. Accordingly, a suitable
way to proceed is to determine the HLB value of the
hydrophobic liquid ingredient (bleach activator), then select
both the hydrophobic nonionic surfactants which have HLB
values below said HLB value of said hydrophobic liquid
ingredient and the hydrophilic nonionic surfactants which
have HLB values above said HLB value of said hydrophobic
liquid ingredient, wherein the difference in the HLB values
of said hydrophobic and hydrophilic nonionic surfactants is
preferably at least 3.
/
W094/29415 ~ 4~1~ PCT~S94/06117
In a preferred embodiment comprising said bleach activator
which is a hydrophobic ingredient, the emulsifying system
meets the equation:
%A %B
HLB(X) = x HLB(A) + x HLB(B) and %A+%B = 100%;
100 100
where X refers to the hydrophobic liquid ingredient to
emulsify, A refers to one of said nonionic surfactants
(hydrophilic or hydrophobic), and B refers to the other said
nonionic surfactant (hydrophilic or hydrophobic).
In a particularly preferred embodiment of the present
invention, wherein the compositions comprise Acetyl triethyl
citrate with an HLB of about lO as the bleach activator, an
adequate nonionic surfactant system would comprise a
hydrophobic nonionic surfactant with an HLB from l to lO, and
a hydrophilic nonionic surfactant with an HLB of above ll. A
particularly suitable system comprises a hydrophobic nonionic
surfactant with an HLB of 6, for instance a Dobanol R 23-2
and a hydrophilic nonionic surfactant with an HLB of lS, for
instance a Dobanol R 9l-lO. Another suitable nonionic
surfactant system comprises a Dobanol R 23-6.5 (HLB about 12)
and a Dobanol R 23 (HLB below 6). All these Dobanol R
surfactants are commercially available from Shell.
Preferably, the compositions according to the present
invention are free of other surfactant types, especially
anionic surfactants.
Depending on the end use envisioned, the compositions
according to the present invention may further comprise a
variety of other ingredients such as perfumes, dyes, optical
brighteners, builders and chelants, pigments, enzymes, dye
transfer inhibitors, solvents, buffering agents and the like.
W094~9415 ~1 Cq 81 S PCT~S94106117
1 1
The compositions according to the present invention are
particularly useful as laundry pretreaters, i.e compositions
which are dispensed and left to act onto fabrics before they
are washed, or as laundry additives to be used together with
detergents to boost their performance, or as dishwashing
compositions to be used either in the dishwashing machines or
by hand, or as hard surface cleaners, or as carpet cleaners
to be used either by direct application onto the carpets or
as detergent for carpet cleaning machines or also alone
without detergents. The compositions according to the
present invention are also particularly adapted to be used
for delicate items.
The present invention further encompasses a process for the
manufacture of the composition described herein. The process
according to the present invention comprises at least three
steps:
In the first step, a hydrophobic mixture is prepared which
comprises said hydrophobic nonionic surfactant and silicone
compounds together with other hydrophobic ingredients which
are to be formulated in the composition, such as perfumes,
solvents, enzymes, bleach activators and polymers.
In the second step, a hydrophilic mixture is prepared which
comprises at least said water, and said hydrophilic nonionic
surfactant. Said hydrophilic mixture preferably further
comprises other hydrophilic ingredients which are to be
formulated in the composition such as dyes, optical
brighteners, builders, chelants, hydrogen peroxide and
buffering agents. In this second step hydrogen peroxide is
preferably added last, after said buffering agent has been
added.
Naturally, said first and said second steps can be performed
in any order, i.e second step first is also suitable.
WO 94/29415 PCT/US94/06117
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In the third step of the process according to the present
invention, said hydrophobic mixture and said hydrophilic
mixture are mixed together.
The present invention is further illustrated by the following
examples.
Examples
Compositions are made which comprise the listed ingredients
in the listed proportions (weight ~).
I II III
Dobanol R 45_7 6 6 6
Dobanol R 9l-lO 3 3 3
Dobanol R 23-2 6 6 6
Hydrogen peroxide 7.5 7.5 7.5
Acetyl triethyl citrate 7.0 7.0 7.0
Brightener 49R 0.20 0.200.20
S,S-ethylene diamino
disuccinic acid O.lO O.lOO.lO
Poly(4-vinylpyridine
-N-oxide) 0.~0 O.lOO.lO
Silicone DB R lO0 _ O.lO0.50
Deionized water ---------balance-------
Density at 30C measured with a floating viscosimeter:
Composition I : p = 0.97
Composition II : p = l.00
Composition III: p = l.Ol
WO94t2~15 Z i 6 ~ 8 ~ 5 PCT~Sg4/06117
_ 13
Viscosity measured with a Brookfield DV II viscosimeter with
spindle RV/6.4 at 300C:
Composition I : 600 cps at 50 rpm
Composition II : 580 cps at 50 rpm
Composition III: 530 cps at 50 rpm
Compositions I to III are each made by preparing two
mixtures. A hydrophilic mixture is prepared which comprises
the water, the brightener, S,S-EDDS, poly(4-vinylpyridine-N-
oxide), the Dobanol R 91-10 and the Dobanol R 45-7. Hydrogen
peroxide is added in said hydrophilic mixture as last step.
A hydrophobic mixture is prepared which comprises the acetyl
triethyl citrate, Silicone DB R 100 and the Dobanol R 23-2.
Then said hydrophobic mixture is poured into said hydrophilic
mixture, while mixing.
According to the present invention, the compositions II and
III which comprise Silicone DB R 100 have a density which is
higher than the density of the composition I which is free of
any silicone compounds. In other words, the compositions II
and III contain less air bubbles than the composition I.
Furthermore, by visual inspection it is also established that
the compositions II and III contain less air bubbles than the
composition I and are therefore more acceptable from a
consumer viewpoint for aesthetic reasons.
Additionally, the compositions II and III (with silicone
compounds) have a lower viscosity than the composition I
which is free of any silicone compounds.
The above results surprisingly show that the use of silicone
compounds in compositions according to the present invention
reduces and substantially eliminates the air bubbles and also
reduces the viscosity of said compositions. Additionally,
the compositions according to the present invention which
WO94/29415 PCT~S94/06117
2l6~l5
comprise silicone compounds are physical stable emulsions,
even more stable than analogous compositions without silicone
compounds.
