Note: Descriptions are shown in the official language in which they were submitted.
WO 94/05757 214 4 0 ~ ~ pCT/GB93/01892
1
IMPROVEMENTS TO HARD SURFACE CLEANERS
Technical Field:
The present invention relates to improvements to hard
surface cleaners, and in particular to hard surface cleaners
containing suspended particles.
Background to the Invention:
Hard surface cleaners containing abrasive particles are well
known. Typical compositions comprise one or more
surfactants in solution and a plurality of abrasive
particles dispersed therein. In this art it is generally
considered necessary to ensure that the abrasive particles
remain in suspension in the composition in order that the
composition need not be vigorously shaken before use and
sedimentation or even cementing of precipitated particles is
prevented.
In one sub-class of compositions, one or more surfactant
components act as a suspending agent, usually in combination
with a dissolved electrolyte. The presence of the
electrolyte causes the surfactant components) to thicken by
the establishment of a lamellar phase.
In another sub-class of compositions, an additional non-
surfactant suspending agent, such as a clay or polymer is
present.
Related compositions are known which comprise non-abrasive
particles such as hygiene agents, i.e. water-insoluble or
sparingly soluble bleaching agents and the present invention
includes such compositions within its scope.
WO 94/05757 PCT/GB93/01892
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2
In such suspending systems, the viscosity of the product
generally varies with the shear applied. This property is
usually referred to as 'shear thinning'. The viscosity
achieved under various rates of shear is important in
determining the product properties.
At low or zero shear, it is desirable that products should
exhibit relatively high viscosity for storage stability of
the suspension without sedimentation of the particles over a
reasonable shelf life. At moderate shear, it is desirable
that products should flow in order that they can be
controllably dosed. At high shear it is desirable that the
viscosity should be sufficiently low to facilitate cleaning
operations using the product.
Surfactants employed as suspending agents in liquid abrasive
cleaners have included, alkyl benzene sulphonates, alcohol
ethoxylates, alkyl amido ethoxylates, fatty acid soaps and
secondary alkyl sulphonates. Combinations of these
surfactants, together with electrolytes are used to form the
suspending systems in a number of commercial products.
As mentioned above, suspending surfactant system must be
both pourable and have a high yield stress, i.e. it must be
dosable and must be capable of suspending macroscopic
particles. The fine structure of such systems generally
consists of generally spherical structures ranging from
about 0.05 to about 10 microns in diameter. These
structures are believed to comprise alternating bilayers of
surfactant molecules spaced apart by thin layers of aqueous
electrolyte solution, i.e. lamellar phase. However, the
suspending system is not the only structure which
surfactants can form in the presence of water. The above-
mentioned surfactants can also form structured aqueous
liquids which are viscous but are not capable of suspending
~144~65
'?461 PCT
partic_es. ._. addition, ~,~mpositicns of surfactant and
water .:~ay separ,at... into t~.~~~, .._ ",cr~ _..ixed bases with
P
different physical propert,_es.
It is particularly desirable, in liquid abrasive cleaners
,.which employ surfactants as the suspending system, that the
suspendig system is stable over t he range of temperatures
encountered in use and sufficiently suspending to maintain
the abrasive particles in suspension for the shelf life of
the product. It is also desirable that the interactions of
other components in t':~e composition with the suspending
surfactants, do not modify the rheology of the overall
composition to an extent gnat the desired shear-r_hinning
property is lost.
Some surfactant combinations form suspending systems more
readily than others. :fixtures of alkyl benzene sulphonates
with alcohol ethoxyiates and, optionally, small amounts of
fatty soaps comprise the suspending surfactant system used
?0 in a number of successful commercial products. A variety ef
electrolytes car. be used with such systems, ,including alkali
metal carbonates, citrates, ha~~ides (particularly chlorides)
phosphates, s,,~iphates, ammonium salts and acetates. Amongst
the ar:icns, the multivaler:t ar_~or.s are preferred for reasons
of cost and due to the additional benefits whic:: these
components bring: suc~: as alkaiir.-~.ty from carbonate and
builder act~~vity from citrate.
G3 2108996 (Bristol Myers, 1x81) discloses liquid abrasive
0 cleaners (LAC's) in wiuich the surfactant system comprises,
as anio~ic detergent, alkyl benzene sulphorate (ABS). The
nor:ionic detergents are present at low levels with a typical
ABS:nonionic rat=o of around 3.5:1.
r;;f;~;,~r;';; ~T
~~44065
03461 aCT
.: a
EP ~36?J16 !Unilever, 1980 c;,scloses LAC's in which t he
sur fact ant system is again A3S _._ combination wit:: lesser
levels o~ nonionics.
Surfactant/electrolyte suspending systems can have a
relatively narrow formulation window within which consumer-
preferrea viscosities must be achieved, depending on the
type of surfactant present.
A problem with surfactant-containing suspending systems is
that some of the surfactants which most readily form
WO 94/05757 214 4 D 6 5 p~/Gg93/01892
4
suspending systems, and are therefore commonly in use, are
not as desirable for environmental reasons as other
surfactant systems.
In particular, primary alcohol sulphate (hereinafter
referred to as PAS) is an environmentally preferable
surfactant, due to its ease of biodegradability and the fact
that it can be obtained from natural, sustainable and hence
renewable sources. It has not proved possible to form
stable suspending systems comprising significant levels of
PAS and relatively low levels of other surfactants. In
addition it is difficult to form stable suspending systems
comprising PAS and multivalent anions such as carbonate,
citrate and sulphate.
Non-suspending systems comprising 1-1.2~ PAS, 0.1-1.5~ of a
mixed non-ionic system and low molecular weight non-
thickening polymer are disclosed in GB 2160887 (Bristol-
Myers: 1984).
Non-suspending surfactant systems, comprising relatively
high levels of PAS in combination with ether-sulphates and
semi-polar non-ionic detergents (such as amine oxides,
phosphine oxides and sulphoxides) are disclosed in GB
1524441 (P&G: 1976).
Complex surfactant systems comprising a plurality of
components including well under 300 on total surfactant of
PAS are taught in EP 0181212 (P&G: 1984) and EP 0039110
(P&G: 1980).
EP 0107946 (P&G, 1983, see Example II) discloses an
unstructured dishwashing composition in which PAS is the
most predominant single surfactant species present but never
exceeds 500 of the total surfactant system.
2144~~5
WO 94/05757 PCT/GB93/01892
EP 0125711 (Unilever, 1983) discloses almost electrolyte-
free, structured liquid compositions comprising polymer,
ethoxylated alcohol surfactants and PAS in a ratio such that
the PAS is never in excess of one third of the total
5 surfactant present.
Of the two known commercial products comprising PAS and a
particulate abrasive, one is notoriously unstable and phase-
separates, in the worst cases, after a few hours of storage
into a thick clay-like mass of particles and a 'cream' of
surfactant separated by a clear liquid layer.
The other product is believed to have comprised 50~ of a
calcite abrasive in a PAS/nonionic/sodium acetate surfactant
system. In the latter case, the high level of abrasive led
to difficulties in rinsing. In general, it is more
difficult to suspend lower levels of abrasive due to to
reduced particle-particle interactions. However, lower
levels of abrasive are desirable in that compositions with
low levels of abrasive are more easily rinsed.
As mentioned above, it is known to use polymers as a part of
the suspending system. Known polymers include poly-
saccharides, e.g. sodium carboxymethyl cellulose and other
chemically modified cellulose materials, xanthan gum and
other non-flocculating structuring agents such as Biopolymer
PS87 referred to in US Patent No. 4 329 448.
Polymers of acrylic acid cross-linked with a poly-functional
agent, for example members of the CARBOPOL (RTM: Goodrich)
family, are also be used as structuring agents in suspending
systems. The amount of such structuring agents can be as
little as 0.001 but is more typically at least 0.01 by
weight of the composition. Commercial products typically
WO 94/05757 PCT/GB93/01892
2~4~~65
6
contain around 0.1-0.4$wt of the cross-linked acrylic acid
polymer.
It is also known to employ at least partially esterified
resins such as an at least partially esterified adduct of
rosin and an unsaturated dicarboxylic acid or anhydride, or
an at least partially esterified derivatives of co-
polymerisation products of mono-unsaturated aliphatic,
cycloaliphatic or aromatic monomers having no carboxy groups
and unsaturated dicarboxylic acids or anhydrides thereof as
deposition agents.
Zypical examples of suitable copolymers of the latter type
are copolymers of ethylene, styrene and vinylmethylether
with malefic acid, fumaric acid, itaconic acid, citraconic
acid and the like and the anhydrides thereof including the
styrene/maleic anhydride copolymers.
It will be appreciated that, polymers are of use where the
surfactant system structures poorly at low shear, i.e. where
storage stability is poor. However polymers have the
disadvantage of also increasing the viscosity at high shear
and therefore increasing the effort required in cleaning
operations using the product.
In order to achieve particular viscosities under specific
shear conditions, is desirable that products should derive
their structural and rheological properties both from a
polymeric structuring agent and from surfactant-electrolyte
interactions. Known products have therefore comprised a
surfactant such as alkyl benzene sulphonate, a co-surfactant
such as an alcohol ethoxylate, an electrolyte and a polymer.
CA 02144065 2002-10-03
Brief Description of the Invention:
we have now devised a stable, particle suspending,
structured liquid composition comprising PAS as a
substantial proportion of the surfactant an electrolyte and,
optionally a polymeric structuring agent. In the context of
the present invention 'stable' should be taken to mean
stable under the condition specified below.
It is believed that the formulations described herein
provide products which are stable under the range of
commonly encountered storage temperatures, exhibit
acceptable cleaning properties and rheology and comprise
relatively higher proportions of the more preferable
surfactants having regard to biodegradation properties than
previously known compositions.
According to the present invention there is provided
a stable, structured, liquid composition comprising a
continuous aqueous,phase, a dispersed lamellar phase and 1-
$0%wt on product of a dispersed, suspended particulate
phase, said product comprising 2-25%wt on~product of
surfactant, said composition further comprising 1-20%
dissolved electrolyte on product, characterised in that said
surfactant comprises primary alcohol sulphate (i) and,
alkoxylated nonionic surfactant (ii) wherein the ratio of
(i) / (ii) falls in the range 20 to 0.4, and wherein the
alkoxylated nonionic surfactant is selected from the
group comprising ethoxylated alcohols of the general
formula:
R-(OCH2CH2~m OH
wherein R is straight or branched, Ca to C18 alkyl and
the average degree of ethoxylation m is 1-14.
Polymers:
High molecular weight hydrophillic polymer is an optional
ingredient of compositions according to the present
invention.
WO 94/05757 21 ~4 0 6 5 PCT/GB93/01892
8
In those embodiments of the present invention which are hard
surface cleaners, it is particularly preferable that such a
polymer is present. Typically compositions will comprise
0.01-2~ of a hydrophillic polymer having a average molecular
weight in excess of 500,000 Dalton.
Without wishing to be bound by any theory of operation, it
is believed that the polymer is of sufficiently high
molecular weight to remain in the continuous phase when
hydrated and that the affinity of the polymer for water,
causes a partial repartitioning of water from the lamellar
phase of the product into the continuous phase of the
product, increasing the effective concentration of
surfactant and electrolyte in the lamellar phase and
improving the structuring properties of that phase.
Preferred types of polymer include poly-carboxylates, poly-
saccharides and mixtures thereof, including co-polymers
within or between these classes or co-polymers with styrenes
and so forth.
Preferred amongst the poly-carboxylates are the crosslinked
poly-acrylates, crosslinked poly-methacrylates, and mixtures
thereof. Crosslinked, poly-acrylates are the most preferred
polymers. These materials are available from a variety of
commercial sources as illustrated hereafter by way of
example.
Preferred amongst the poly-saccharides are xanthan and guar
gums, cellulose ethers, and mixtures thereof.
Preferred levels of polymer are 0.05-1~ on product, more
preferably 0.1-0.5wto with levels of around 0.1-0.3 being
particularly preferred for the cross-linked poly-acrylate,
so as to achieve the desired viscosity.
WO 94/05757
6 5 PCT/GB93/01892
9
In general, the levels of polymer present should be such
that the viscosity, as measured at 25 Celsius, at a shear
rate of 21 sec-' falls in the range 300-2500 mPas. It is
particularly preferred that the viscosity at this shear rate
should fall into the range 600-1800 mPas. Such viscosities
facilitate easy dosing.
The viscosity at lower rates of shear, i.e below 10-3 sec-1
should be sufficiently high to provide for storage stability
of the product in that significant particle sedimentation
should be avoided.
The viscosity at higher rates of shear, i.e above 100 sec~l
should be sufficiently low provide for ergonomic use of the
product and avoid excessive effort being required in use.
In compositions according to the present invention in which
the particles are chemically reactive, suspended, hygiene
agents rather than chemically inert abrasives, polymer is
not an essential component but where present a polymer
should be selected which is chemically stable in the
presence of the hygiene agent.
Surfactant System:
Primary alcohol sulphates and alkoxylated nonionic
surfactants are essential ingredients of the compositions
according to the present invention.
Preferably, the ratio of primary alcohol sulphate (i) to the
one or more nonionic surfactants (ii), expressed as (i)/(ii)
in weighty falls in the range 5-0.45. More preferably the
ratio falls into the range 2-0.6. Even more preferably the
ratio falls is 1.5-0.75 and is most preferably around 1.
CA 02144065 2002-10-03
WO 94/05757 PCT/GB93/01892
5
As mentioned above, primary alcohol sulphate (hereinafter
referred to as PAS) is an environmentally desirable
surfactant, due to its ease of biodegradability and the fact
that it can be obtained from renewable sources.
The preferred primary alcohol sulphate comprises a mixture
of materials of the general formulation:
ROS03X
15
wherein R is a C8 to Cls (mean chain length) primary alkyl
group and X is a solubilising canon: Suitable cations
include sodium, magnesium, potassium, ammonium and mixtures
thereof.
C8-18 (mean chain length) PAS is preferred due to its
detergent and structuring properties. Above mean alkyl
chain lengths of C18, the material tends to become too
insoluble for use, whereas below mean chain lengths of C8
the material tends to become too soluble for use. C10-C16
(mean chain length) PAS is particularly preferred as
materials with this chain length average have optimal
detergent properties and are readily available.
The preferred alkoxylated non-ionic surfactants are selected
from the group comprising alkoxylated: alkyl polyglucosides,
alcohols, alkyl sulphoxides, alkyl polyglycerols, fatty acid
esters, amides and amines and mixtures thereof.
As noted above, the nonionic surfactant is selected from the
group comprising ethoxylated alcohols of the general
formula: .
R1- (OCH2CHz ) m A-OH
WO 94/05757 2 ~. 4 4 D 6 5 PCT/GB93/01892
11
wherein R1 is the residue of a branched, or unbranched, C8 to
C18 preferably primary, alcohol, A is preferably absent or is
the residue of a polyol of at least two carbons and two
hydroxyl groups, and the average degree of ethoxylation
(i.e. the ethylene oxide chain length) m is 1-14. R1 can be
a 2-hydroxy alkyl residue of the same chain length.
Where A is present it can be the residue of an alkylene
glycol or a sugar. Generally, A will be absent. It should
be noted that propoxy residues can replace the ethoxy
residues in whole or in part.
The alcohol ethoxylates are excellent detergents, available
at low cost in commercial quantities and exhibit
concentration-sensitive interactions with electrolyte and
PAS enabling the formation of a suspending system.
Optimum detergent properties are obtained where m is (mean
for the surfactant) in the range 1-14.
Most preferred amongst the ethoxylated alcohols are those
which have m less than or equal to 10. These shorter chain
ethoxylated alcohols have better biodegradability than the
longer chain ethoxylated alcohols, and it becomes
progressively more difficult to form a suspending system
with the longer ethoxylate chain ethoxylated alcohols.
In preferred embodiments of the invention the overall
surfactant system consists of: 2-10~ primary alcohol
sulphate (i) and 2-10~ ethoxylated alcohol (ii) in a weight
ratio of (i)/(ii) which falls in the range 2.0-0.6 , and,
0.1-2~ of a fatty acid soap having a mean of C10-C18 carbon
atoms.
WO 94/05757 PCT/GB93/01892
2~.44Qfi5
12
Electrolyte:
Electrolyte is an essential component of compositions
according to the present invention.
For the longer chain ethoxylated alcohols, wherein m (the
average degree of ethoxylation) is greater than 5, i.e.
generally 5-10, monovalent anion electrolyte needs to be
present in weight excess over the total surfactant present
in the composition: whereas either monovalent or divalent
anions can be used as the electrolyte with the shorter chain
ethoxylates (i.e where m is less than or equal to 5).
Consequently, preferred embodiments of the present invention
comprise:
a) 2-25~wt surfactant on aqueous phase, said
surfactant comprising primary alcohol sulphate (i)
and one or more ethoxylated alcohols (ii) of the
general formula:
R1- ( OCHzCHz ) m-OH
wherein R1 is straight or branched, C8 to C18 alkyl
and the average degree of ethoxylation m is 5-10,
b) a weight-excess of electrolyte on aqueous phase as
compared with (a), said electrolyte comprising a
salt in which the anion is monovalent, and,
c) 0.01-20 of a hydrophillic polymer having a average
molecular weight in excess of 500,000 Dalton.
Preferably, the monovalent anions are selected from the
group comprising chlorides, bromides, iodides, acetates,
WO 94/05757 PCT/GB93/01892
~144~65
13
bicarbonates, and mixtures thereof having regard to the
chemical nature of the particulate phase such that where the
particulate phase is chemically reactive, the electrolyte is
selected to be inert towards the particulate phase.
The preferred ratio's of the surfactants are as described
above.
As mentioned above, we have determined that, when the
ethoxylated alcohols have m less than or equal to 5, it is
possible to formulate stable products in which the
electrolyte solution comprises either multivalent or
monovalent anions. In those compositions in which the
ethoxylated alcohols have m greater than or equal to 5, it
is not possible to formulate products in which the
electrolyte solution comprises significant levels of
multivalent anions.
Consequently, preferred embodiments of the present invention
comprise:
a) 2-25~wt surfactant on aqueous phase, said
surfactant comprising primary alcohol sulphate (i)
and one or more ethoxylated alcohols (ii) of the
general formula:
R~ - ( OCHZCHz ) m-OH
wherein R1 is straight or branched, CB to C18 alkyl
and tree average degree of ethoxylation m is 1-5,
b) 1-20~wt electrolyte on aqueous phase, and,
c) 0.01-2~ of a hydrophillic polymer having a average
molecular weight in excess of 500,000 Dalton.
WO 94/05757 PCT/GB93/01892
z~44os5 14
Preferably, said electrolyte comprises 25-100mo1e~
multivalent anions on total anions.
Preferably, the multivalent anions are selected from the
group comprising, carbonates, citrates, sulphates and
mixtures thereof. Carbonates alone, or mixtures comprising
carbonates are particularly preferred.
The presence of multivalent anions is preferred due to the
benefits of alkalinity (with carbonates) and builder
activity (with both carbonates and citrates).
Preferred levels of electrolyte fall in the range 1-100,
more preferably 2-80. It is particularly preferred that the
anions of the electrolyte comprise at least 50mole~
carbonate.
Particulate Phase:
A dispersed, suspended particulate phase is an essential
ingredient of compositions according to the present
invention.
Preferably, the dispersed suspended particulate phase
comprises a particulate abrasive which is either insoluble
in the aqueous phase or present in such excess that the
solubility of the abrasive in the aqueous phase is exceeded
and consequently solid abrasive exists in the composition.
Preferred abrasives for use in general purpose compositions
have a Moh hardness below 6 although higher hardness
abrasives can be employed for specialist applications.
Suitable abrasives can be selected from, particulate
zeolites, calcites, silicas, silicates, carbonates,
WO 94/05757
PCT/GB93/01892
aluminas, bicarbonates, borates, sulphates, and, polymeric
materials such as polyethylene.
Preferred average (weight average) particle sizes for the
5 abrasive fall in the range 0.5-200 microns, with values of
around 10-100 microns being preferred. In this range an
acceptable compromise between good cleaning behaviour and
low substrate damage is achieved.
10 Preferred levels of abrasive range from 5-70wt~ on product,
preferably in the range 20-40wt%, most preferably around
35wt%. Such levels of abrasive give effective cleaning and
good rinsing.
15 The most preferred abrasives are calcium carbonate (as
calcite), mixtures of calcium and magnesium carbonates (as
dolomite), sodium hydrogen carbonate, potassium sulphate,
zeolite, alumina, hydrated alumina, feldspar, talc and
silica. Calcite and dolomite are particularly preferred due
to their low cost, hardness and colour.
Preferably, where the suspended particulate phase is calcite
at 50$wt on product the electrolyte is other than acetate.
As mentioned above it is progressively more difficult to
formulate compositions with more dense as opposed to less
dense particles, consequently, the particles used in
embodiments of the present invention preferably have a
density lower than 2.7 gm/cm3: this excludes unmodified
calcite. Where calcite is used it should be used at levels
below 50~ on product in order to improve rinsing
performance. The suspending systems of the present
invention are capable of suspending calcite at relatively
low levels, i.e. 20-40~wt, at which levels particle-particle
WO 94/05757 PCT/GB93/01892
2~_44~65~.
16
interactions are reduced as compared with higher levels of
calcite.
Without wishing to be restricted by theory, is believed that
there is an interaction between the calcite and polymer, in
the continuous phase, which leads to the formation of a
complex structure comprising both polymer and calcite. It
is believed that this structure has an effective density
lower than that of calcite (s. g. 2.7-2.9) and consequently
the calcite is less difficult to suspend in systems
according to the present invention.
In the alternative, the particulate phase can comprise a
hygiene agent, preferably a solid organic peracid. Examples
of such hygiene agents include diperoxy-dodecanedioic acid
(DPDA) and e-N-N-phthaloyl-amino-peroxy-caproic acid (PAP).
Alternative, insoluble hygiene agents include triclosan
(2,4,4'-trichloro-2'-hydroxy diphenyl ether) and insoluble
derivatives thereof. These may be present in combination
with or to the exclusion of the abrasive particles.
Solvents:
In addition to the abovementioned components compositions
according to the present invention can comprise a solvent.
Solvents are an optional component and are not essential to
the practice of the present invention.
Preferred solvents are selected from: propylene glycol mono
n-butyl ether, dipropylene glycol mono n-butyl ether,
propylene glycol mono t-butyl ether, dipropylene glycol mono
t-butyl ether, diethylene glycol hexyl ether, ethyl acetate,
methanol, ethanol, isopropyl alcohol, ethylene glycol
monobutyl ether, diethylene glycol monobutyl ether, n-methyl
pyrollidone and mixtures thereof.
WO 94/05757 ~ ~ ~ ~ ~ ~ PCT/GB93/01892
17
The preferred solvents are propylene glycol mono n-butyl
ether, dipropylene glycol mono n-butyl ether, ethanol,
isopropyl alcohol, diethylene glycol monobutyl ether and
mixtures thereof.
Minors:
The compositions of the invention can further comprise other
non-essential components selected from the group comprising:
perfumes, colours, whitening agents (such as titanium
dioxide) and dyes, hygiene agents, foam-control agents,
preservatives and mixtures of one or more thereof.
Preferably the foam control agents comprise calcium
sensitive soaps. Particularly preferred soaps are the C10-
C18 saturated or unsaturated fatty acids and salts thereof.
Preferred levels of soap range from 0.1-2$ of a fatty acid
soap having C10-C18 carbon atoms. It is particularly
preferred that the ratio of soap to total active should fall
into the range: 1:5-1:20.
As will be elaborated upon hereafter, while not necessary,
the presence of fatty acid soap is required for preferred
process aspects of the present invention.
Having regard to the various constraints and preferred
features required to obtain optimum performance,
particularly preferred embodiments of the present invention
provide a stable, liquid composition comprising a continuous
aqueous phase arid a dispersed, suspended particulate phase,
wherein the particles comprise calcite, dolomite,
bicarbonate and mixtures thereof, and the aqueous phase
comprises:
WO 94/05757 PCT/GB93/01892
2~ 4065
18
a) 2-10~ primary alcohol sulphate comprising a
mixture of materials of the general formulation:
ROS03X
wherein R is a Clo to C16 primary alkyl group and X
is a solubilising cation selected from the group
comprising sodium, magnesium, potassium, ammonium
and mixtures thereof,
b) 2-10~ ethoxylated alcohols of the general formula
R1- (OCHZCHZ ) m~H
wherein R1 is straight or branched, C8 to C18 alkyl
and the average degree of ethoxylation m is 1-5,
wherein the ratio of a:b falls in the range 1:2 to
2:1,
c) 1-l0~wt electrolyte on aqueous phase, said
electrolyte comprising 25-100moleo multivalent
anions selected from the group comprising
carbonates, citrates, sulphates and mixtures
thereof on total anions,
d) 0.1-2~ of a fatty acid soap having C10-C18 carbon
atoms, and,
e) 0.1-0.50 of a hydrophillic, crosslinked polymer
having a average molecular weight in excess of
500,000 Dalton.
WO 94/05757 ~ ~ 4 4 0 6 5 P~/GB93/01892
19
Process Aspects:
Further aspects of the present invention concerns the
process.
Primary alcohol sulphate (PAS) is unstable in the acid form,
decomposing to the corresponding alcohol and oxides of
sulphur. This difficulty does not arise with the commonly
used linear alkyl benzene sulphonate (LAS) surfactants which
are stable in the acid form. Consequently, PAS is commonly
handled and transported as an aqueous solution of around
30~wt or 70owt concentration, neutralised with a suitable
base, such as sodium or ammonium hydroxide, to form an
alkali metal salt solution, whereas LAS, as the acid, can be
handled and transported in substantially anhydrous form as a
viscous liquid.
PAS forms a gel phase at concentrations above 30~wt in
aqueous solution, depending on the chain lengths of the PAS
and degree of branching and remains in this phase until
higher concentrations, of around 70~ are reached, where a
pumpable phase is again formed. Compositions which comprise
both polymers and PAS are difficult to prepare as the
production process must not at any stage form a composition
in which the PAS or the polymer form a significant quantity
of gel. Gels can be formed, when PAS and polymer are mixed,
due to the reduction of the water activity in the PAS caused
by the presence of the polymer and subsequent competition
for the available water.
Moreover, certain hydrophillic, high molecular weight
polymers, such as the crosslinked polyacylates should not be
exposed to other than mildly alkaline conditions as such
conditions will cause gelling of the polymer. In addition,
WO 94/05757 PCT/GB93/01892
214~.fl65
these polymers cannot be dissolved at high concentrations in
neutral aqueous solution.
Where abrasive components are present, initial suspension of
abrasives in the absence of a suspending system requires
high shear which can incorporate air into any viscous
mixture which is formed during mixture of components. This
air is difficult to remove.
We have now determined how aqueous compositions comprising
the preferred hydrophillic high molecular weight polymers,
particulate abrasives and primary alcohol sulphates can be
prepared without the abovementioned difficulties.
Accordingly, a further aspect of the present invention
provides a process for the preparation of a cleaning
composition which comprises the steps of:
a) obtaining a mixture of 1-3~wt hydrophillic polymer
having a molecular weight in excess of 500,000 and
water, substantially free of electrolyte,
b) separately to (a) obtaining a premix of primary
alcohol sulphate, and at least 20% water,
c) separately to (a) and (b) obtaining a suspension
of particulate abrasive in an aqueous electrolyte
solution.
d) combining the products of steps (a), (b) and (c)
with a fatty acid and a nonionic surfactant such
that the mixture at no stage comprises:
i) both the products of steps (a) and (b) in the
absence of fatty acid, or,
WO 94/05757 ~ ~ ~ 6 ~ PGT/GB93/01892
21
ii) nonionic surfactant and the product of step
(a) in the absence of the products of steps
(b) or the product of step (c).
One particularly preferred process route comprises:
a) obtaining a mixture of the fatty acid and the
polymer, and combining the said mixture with water,
b) combining primary alcohol sulphate surfactant with
the product of step (a), and,
c) combining the product of step b) with electrolyte,
abrasive and nonionic.
An alternative preferred process route comprises:
a) preparing a mixture of electrolyte, abrasive and
water,
b) mixing with the product of step (a), fatty acid,
primary alcohol sulphate, and nonionic surfactant, and
c) preparing a separate premix of water and the
polymer and combining this premix with the product of
step (b).
In order that the present invention may be further
understood it will be explained hereafter with reference to
examples and by reference to the accompanying figures 1-4
which are:
Figure 1: shows the lamellar regions for formulations
containing either PAS or alkyl benzene sulphonate with
a 6.5 EO nonionic surfactant at varying levels of
electrolyte levels,
WO 94/05757 PCT/GB93/01892
22
Figure 2: shows the lamellar regions for formulations
containing either PAS and a nonionic surfactant at
varying electrolyte levels and for varying
environmental conditions,
Figure 3: shows the lamellar regions for formulations
containing PAS with a 3.0 EO nonionic surfactant at
varying mono-valent electrolyte levels,
Figure 4: shows the lamellar regions for formulations
containing PAS with a 3.0 EO nonionic surfactant at
varying di-valent electrolyte levels,
Figure 5: shows the lamellar regions for formulations
containing PAS with a 6.5 EO nonionic surfactant at
varying mono-valent electrolyte levels,
EXAMPLES:
In order to illustrate the storage stability of the products
according to the present invention four sets of storage
conditions were employed.
These storage conditions are intended to model the
environments encountered by the product during transport and
storage either prior to, or after, sale of the product. The
conditions are:
1) AMBIENT: Products were stored in closed containers,
without agitation, for ten days at laboratory
temperature (15-25 Celsius).
2) COLD: Products were stored in closed containers,
without agitation, for twelve weeks at a
WO 94/05757 ~ 4 ~ ~ ~ ~ PCT/GB93/01892
23
temperature of 4 degrees Celsius in a
thermostatted cold-box.
3) FREEZE: Products were stored in closed containers,
without agitation, for ten days at a
temperature of -10 degrees Celsius in a
thermostatted cold-box.
4> WARM: Products were stored in closed containers,
without agitation, for ten days at a
temperature of 37 degrees Celsius in a
thermostatted oven.
5) CYCLE: Products were stored in closed containers,
without agitation, during ten temperature
cycles, each of a twenty-four hour duration
and each consisting of eight hours at -5
degrees Celsius followed by sixteen hours at
degrees Celsius.
At the end of each of the above-mentioned storage tests,
products were, allowed to come to room temperature, examined
visually and were categorised either as 'stable', where
little or no phase separation had occurred; or 'unstable'
where sedimentation of the abrasive had occurred to a
clearly visible extent. The sedimentation of abrasive was
generally accompanied by the formation of an at least 1mm
clear layer in the product.
The materials listed below are identified both by the names
used in the following examples and by their trade-names:
CA 02144065 2002-10-03 ~ ..
WO 94/05757 PGT/GB93/01892
24
Polvmers:
PolyGelTM DB [RTM ex Sigma], a cross-linked
polyacrylate supplied as a powder,
AlcogumTM SL71 [RTM ex Alco/National Starch], an
acrylic terpolymer commercial gum,
AlcosperseTM 602N [RTM ex Alco/national Starch], a linked
acxylate copolymer commercial gum,
rt...,
National 467-100 [RTM ex National Starch], a cross-linked
polymethacrylate-styrene copolymer,
National 467-45 [RTM ex National Starch], a cross-linked
polymethacrylate-styrene copolymer,
KelzanTM T [RTM ex Kelco]. a xanthan gum
Surfactants:
LIAL-123S [RTM ex. DAC], a sodium salt of
synthetic, partly branched, primary
alcohol sulphate having an average alkyl
chain length in the range Clz-C13 %
EmpicolTM-LX [R~ ex Albright & Wilson], a sodium
salt of naturally derived, linear,
primary alcohol sulphate having an
average alkyl chain length in the range
Ciz-Ci4 %
CA 02144065 2002-10-03
WO 94/05757 PGT/G B93/01892
SynperonicTM A3 [RTM ex. ICI], an alcohol ethoxylate,
nonionic surfactant having an average
ethylene oxide chain length of 3 units.
5 SynperonicTM A7 [RTM ex. ICI), an alcohol ethoxylate,
nonionic surfactant having an average
ethylene oxide chain length of 7.5
units.
_. 10 DobanolTM 23-6.5 [RTM ex, Shell , an alcohol ethoxylate
surfactant having an average ethylene
oxide chain length (E0) of 6.5 units.
DobanolTM 91-2.5 [RTM ex. Shell], an alcohol ethoxylate
15 surfactant having an average ethylene
oxide chain length (E0) of 2.5 units.
PrifacTM 7901 [RTM ex. Unichema], a mixed chain-length
fatty acid having a similar chain length
20 distribution to the fatty acids
obtainable from coconut oil.
Abrasive:
25 MMSF Calcite [ex. Minerva].
Minors:
CL318A Perfume (ex. Quest International), a
commercially available oily fragrance
with a citrus odour.
LindaliaTM Perfume (RTM ex. Firmenich), a
conunercially available fragrance with a
flowery odour.
WO 94/05757 PCT/GB93/01892
2~~ 4.4Qfi5
26
Proxel Preservative (RTM ex. ICI).
Products were prepared by the following processes:
Process 1:
a) A premix was prepared of the fatty acid (soap) and the
polymer, under moderate shear, using a Janke and Kunkel
mixer with a star-shaped blade at a temperature of 50
Celsius.
b) The premix of (a) is dispersed in approximately one
third of the water at 50 Celsius using a Janke and Kunkel
mixer with a standard impeller.
c) The primary alcohol sulphate surfactant is added to the
product of (b), as a paste of 70~ active, preheated to a
temperature of 37 Celsius. The non-ionic surfactant is
either added at this point, after preheating to 35-45
Celsius or added as mentioned at (d) below.
d) The balance of the water is placed in a vessel at a
temperature of 37 Celsius, followed by the electrolytes
which are dissolved by stirring. The calcite is added with
continuous stirring followed by the premix of (c). The non-
ionic is added at this stage if not added at (c).
e) Preservative and volatile minors such as perfume, are
added to the mix with stirring until a homogeneous
dispersion is achieved.
WO 94/05757 PCT/GB93/01892
~14~~~5
27
Process 2:
a) A premix was prepared of the fatty acid, approximately
one third of the water and the primary alcohol sulphate
surfactant as a paste of 70~ active at 37 Celsius using a
Janke and Kunkel mixer with a standard impeller. The non-
ionic surfactant is either added at this point, after
preheating to 35-40 Celsius or added as mentioned at (b)
below,
b) The balance of the water is placed in a vessel at 37
Celsius followed by the electrolytes which are dissolved by
stirring. The calcite is added with continuous stirring and
the resulting product mixed with the premix of (a). The
non-ionic is added at this stage if not added at (a),
c) A separate premix of the polymer in 2~ aqueous solution
is prepared, under moderate shear, using a Janke and Kunkel
mixer with a standard impeller at ambient temperature,
d) The premix of (c) is added to the product of step (b),
e) Preservative and volatile minors such as perfume, are
added to the mix with stirring until a homogeneous
dispersion is achieved.
Process 3:
a) A premix was prepared of the fatty acid (soap) and the
polymer, under moderate shear, using a Janke and Kunkel
mixer with a star-shaped blade at a temperature of 50
Celsius,
WO 94/05757 PCT/GB93/01892
2~~~065
28
b) The premix of (a) is dispersed in approximately one
third of the water at 50 Celsius using a Janke and Kunkel
mixer with a standard impeller,
c) The balance of the water is placed in a vessel at 37
Celsius followed by the electrolytes which are dissolved by
stirring. The calcite is added with continuous stirring
using a Janke and Kunkel mixer with a standard impeller. To
the mixture thus obtained, the primary alcohol sulphate
surfactant as a solution of 27o active was added,
d) The product of step (b) was combined with the product
of step (c), and the nonionic added after preheating to 35-
40 Celsius, and,
e) Preservative and volatile minors such as perfume, are
added to the mix with stirring until a homogeneous
dispersion is achieved.
Process 4:
a) A premix of the polymer in 2% aqueous solution is
prepared, under moderate shear, using a Janke and Kunkel
mixer with a standard impeller at ambient temperature,
b) The balance of the water is placed in a vessel at 37
Celsius followed by the electrolytes which are dissolved by
stirring. The calcite is added with continuous stirring
using a Janke and Kunkel mixer with a standard impeller. To
the mixture thus obtained, the primary alcohol sulphate
surfactant as a solution of 27% active was added, followed
by nonionic added after preheating to 35-40 Celsius and
optional fatty acid,
WO 94/05757 2 ~ ~0 5 PCT/GB93/01892
29
c) The product of step (a) was combined with the product
of step (b) , and,
d) Preservative and volatile minors such as perfume, are
added to the mix with stirring until a homogeneous
dispersion is achieved.
Examples 1-7:
TABLE 1 below shows the storage stability of compositions
according to the present invention and comparative examples
which were either unstable or had unacceptable viscosity
character-istics. These examples illustrate the importance
of polymer.
TABLE 1
EXAMPLE I 1 I 2 I 3 I 4 I 5 ~ 6 ~.
PolyGel DB 0.15 - 0.20 - 0.20 - 0.20
Lial-123S 3.25 3.22 3.22 3.57 3.57 2.86 2.86
Synperor~ic A3 3.25 3.22 3.22 2.86 2.86 3.22 3.22
Prifac 7901 0.65 0.71 0.71 0.71 0.71 1.07 1.07
NaZC03 2.60 3.25 3.25 3.25 3.25 3.25 3.25
NaHC03 0.65 - - - - - -
Calcite 35.0 35.0 35.0 35.0 35.0 35.0 35.0
Lindalia 0.21 0.21 0.21 0.21 0.21 0.21 0.21
Proxel 0.03 0.03 0.03 0.03 0.03 0.03 0.03
Water ___________________to
100-____________
Process: 3 4 4 4 4 4 4
i~iscosity: 1840 380 2210 Unst 1730 Unst 1900
WO 94/05757 PCT/GB93/01892
~.~4~Q65
Viscosity was measured at 21 sec-1, at 25 Celsius using a
Haake RV2 as supplied, with the MV cup provided with the MV2
bob. Results are given in mPas.
5 Comparative examples 4 and 6 showed unstable, many-phase
behaviour and consequently the viscosity of these products
was not measured.
Example 2 illustrates that while a stable product can be
10 made without polymer the viscosity of the product under the
shear conditions specified is undesirably low.
Examples 1,3, 5, and 7 are embodiments of the invention.
The products of examples 1-3, 5 and 7 were all stable under
15 storage conditions 1 and 3-5 as described above.
Examples 8-15:
TABLE 2 provides examples showing that other polymers can be
20 employed at various levels.
WO 94/05757 ~ Q ~ ~ PCT/GB93/01892
31
TABLE 2
EXAMPLE 8 9 10 11 12 13 14 15
PolyGel DB 0.12 - - - - - - -
N-467-45 - 0.30 0.20 - - - - -
N-467-100 - - - 0.30 - - - -
Alcogum - - - - 0.20 0.10 - -
Kelzan-T - - - - - - 0.10 0.30
Lial-123S 3.25 3.25 3.25 3.25 3.22 3.22 3.25 3.25
Synperonic A3 3.25 3.25 3.25 3.25 3.22 3.22 3.25 3.25
Prifac 7901 0.65 - - - - - 0.65 0.65
ratio PAS/NI 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
Na2C03 2.60 3.25 3.25 3.25 3.25 3.25 3.25 3.25
NaHC03 0.65 - - - - - - -
Calcite 35.0 35.0 35.0 35.0 35.0 35.0 35.0 35.0
Lindalia 0.21 0.21 0.21 0.21 0.21 0.21 0.21 0.21
Proxel 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03
Water _________________to
100-__________________
Process: 1 4 4 4 4 4 4 4
Viscosity: 1200 1340 890 583 2000 1360 800 1460
Viscosity was measured at 21 sec-1, at 25 Celsius using a
Haake RV2 as supplied, with the MV cup provided with the MV2
bob. Results are given in mPas.
All products were found to be stable under conditions 1 and
3-5 as described above.
Examples 8-15 illustrate that stable compositions according
to the present invention can be prepared with acceptable
viscosity using alternative polymers.
WO 94/05757 PCT/GB93/01892
z~~4Q65
32
Examples 16-18:
Table 3 shows the effect of modification of the surfactant
system.
TABLE 3
EXAMPLE 16 17 18
PolyGel DB I 0 .12 0 .12 0 .12
I ~
Lial-123S 3.25 3.25 3.25
Dobanol-6.5 3.25 - -
Dobanol9l-2.5 - 3.25 -
Synperonic A7 - - 3.25
Prifac 7901 0.65 0.65 0.65
~ ratio PAS/NI 1. 1. 1 .
I 00 00 00
I ~
Na2C03 2 . 2 . 2 .
6 6 6
0 0 0
NaHC03 0.65 0.65 0.65
Calcite 35.0 35.0 35.0
Lindalia 0.21 0.21 0.21
Proxel 0.03 0.03 0.03
Water ----to
1000-----
Process: 1 1 1
Viscosity: Unst 1400 Unst
Viscosity was measured at 21 sec-1, at 25 Celsius using a
Haake RV2 as supplied, with the MV cup provided with the MV2
bob. Results are given in mPas.
Comparative Examples 16 and 18 illustrate that in the
presence of electrolyte based on divalent anions
WO 94/05757 ~ ~ ~ ~ a ~ ~ PCT/GB93/01892
33
(carbonate), compositions wherein the ethoxyiate has a
ethoxy chain length of greater than 5 are unstable.
Example 17 illustrates that an embodiment of the present
invention formulated with a non-ionic having a shorter
ethoxy chain is stable in comparison with the Examples 16
and 18. This sample was stable when stored as described
above.
EXAMPLES 19-23:
Examples 19-23 illustrate the results of a plurality of
experiments relating to lamellar phase of a range of
compositions based on PAS, nonionics and electrolytes, in
the absence of minors. The results of examples 19-21 are
shown in the accompanying figures 1-5. The process routes
used to obtain the compositions of examples 19-23 were
selected from processes 1-4 as mentioned above or were minor
modifications thereupon.
In order to determine whether a relatively stable lamellar
phase was present, liquid samples of the compositions were
examined after at least three days storage at the specified
temperatures. A small sample was placed between glass
slides and examined using polarised light, transmission
microscopy. The presence of a lamellar phase was indicated
by a characteristic 'Maltese cross' pattern generally
believed to be caused by the presence of a lamellar phase
dispersion.
Figure 1: (Example 19a) shows the stable lamellar regions
for formulations containing either PAS (Empicol LX) or alkyl
benzene sulphonate together with a 6.5 EO nonionic
surfactant (Dobanol 23 6.5 EO) at a constant total
surfactant level of l0owt and at varying electrolyte levels.
WO 94/05757 PCT/GB93/01892
2.144005 34
In this example the electrolyte was sodium chloride and
stability was assessed at 25 Celsius. From figure 1, it can
be seen that, the existence of a lamellar phase depends on
both the selection of the correct electrolyte level and the
correct ratio of surfactants. With the alkyl benzene
sulphonate/non-ionic surfactant systems of the prior art
(Region A), lamellar-phase formulations can be made over a
relatively wide formulation range. With the primary alkyl
sulphate/non-ionic surfactant system employed in the
compositions of the present invention, the range of
electrolyte levels and surfactant ratios which enable the
formation of a lamellar phase (Region B) is markedly
smaller. When the electrolyte was changed from NaCl to
sodium carbonate, supplying a divalent cation (Example 19b),
no lamellar phase region could be found (see also examples
16 and 18).
Figure 2: (Example 20) shows the stable lamellar regions for
formulations containing both sodium PAS (Empicol LX) and a
6.5 EO nonionic surfactant (Dobanol 23 6.5 EO) at varying
ratios to a constant total surfactant level of 10%, at
varying levels of electrolyte (sodium chloride) and under
varying environmental conditions. These conditions are 1,2
and 4 as discussed above and the limits of the boxes marked
1, 2 and 4 indicate the limits of stability under the
specified conditions. It can be seen that for general
stability under a practical range of storage conditions over
a temperature range of 4-37 Celsius, the preferred range of
electrolyte levels and surfactant ratios is particularly
narrow (Region C). Outside of this region not all of the
formulations produce the lamellar phase and the formulations
would consequently not be capable of suspending particles
under certain conditions of storage.
WO 94/05757 ~ ~ (~(~, y s ~ PCT/GB93/01892
Figure 3: (Example 21) shows the stable lamellar regions at
25 Celsius for formulations containing PAS (Empicol LX) with
a 3.0 EO nonionic surfactant (Synperonic A3) at a total
surfactant level of 10~ and at varying electrolyte (NaCl)
5 levels. It can be seen that for these short-chain
ethoxylates in combination with PAS the ranges over which a
lamellar phase (Region D) can be formed in the presence of a
monovalent ration electrolyte (sodium chloride) are much
larger than with the corresponding higher EO compositions.
Figure 4: (Example 22) shows the stable lamellar regions at
25 Celsius for formulations containing PAS (Empicol LX) with
a 3.0 EO nonionic surfactant (Synperonic A3) at a constant
surfactant level of l0~wt on product and at varying di-
valent ration electrolyte (sodium carbonate) levels. The
region over which a lamellar phase can be formed (Region E)
is indicated. It is noted that with the same electrolyte
and higher levels of ethoxylation in the surfactant (compare
Examples 16, 18 and 19b) no lamellar region could be found,
although, in this instance, with the 3.0 EO surfactant and
carbonate a small region exists in the phase diagram wherein
a lamellar phase could be found. This region is much
smaller than the corresponding region with the mono-valent
anion (compare with Example 21).
Figure 5: (Example 23) shows the stable lamellar regions at
25 Celsius for formulations containing various ratios of PAS
(Empicol LX) with a 6.5 EO nonionic surfactant (Dobanol 23-
6.5) at a total surfactant level of 10$ and at varying mono-
valent ration electrolyte levels. In this instance, as
compared with Example 19a, the ration is ammonium as opposed
to.sodium. It is to be noted that relatively high levels of
electrolyte are required to form a lamellar phase. High
levels of electrolyte are discouraged for reasons of residue
deposition and corrosiveness.
WO 94/05757 PCT/GB93/O1892
36
EXAMPLES 24-26:
TABLE 4 below shows the storage stability of compositions
according to the present invention and comparative examples
which were unstable. None of these compositions comprise
polymer.
All compositions were prepared by mixing the components as
listed, under shear, at room temperature.
In examples whose number is not suffixed by a letter (i.e.
examples 24, 25 and 26?, the formulations were stable in all
four of the storage regimes described above. In examples
whose number is suffixed by letter, the compositions were
unstable under one or more of the storage conditions.
Ratios of PAS to nonionic for the formulations are given in
the table. None of the compositions were stable if
electrolyte was omitted.
WO 94/05757 ~ ~ 4 4 U 6 5 PCT/GB93/01892
37
a~
o ~r, o Ln in in co.L?
lp 111 COl0 N l0 Lf7(a
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M 'd~ (~O M O O (!)
N
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tf1 N CO vD N ~ COU7
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M V' d' O M O O
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WO 94/05757 PCT/GB93/01892
~.~4~ Ofi5
38
From the table it can be seen that for compositions to be
stable under all storage conditions, it is necessary for
electrolyte to be present and for the PAS to nonionic ratio
to not be too low (example 24 compared with 24A).
The choice of electrolyte which can be used is somewhat
dependent on the nature of the nonionic surfactant. When
longer ethylene oxide chain, nonionic, surfactants such as
Dobanol 23-6.5E0 are used, it is particularly preferable
that the electrolyte contains a monovalent anionic species
such as a halide, preferably chloride. Examples 24 and 24C
illustrate this point: the formulation was unstable when the
divalent carbonate was employed instead of the monovalent
chloride.
Furthermore, for the longer chain ethoxylated alcohols,
wherein m is greater than 5, the electrolyte very preferably
needs to be present in weight excess over the total
surfactant present in the composition (compare example 25
with example 25B)
However, when short chain, non-ionic ethylene oxide chain
surfactant are used (such as Synperonic A3: 3E0, as in
example 25 and example 26) it is possible to formulate
stable products with electrolyte salts comprising
multivalent anionic species such as carbonates (compare
example 25 with example 25A), irrespective of the type of
PAS (compare example 25 and example 26). The level of
electrolyte need not exceed the total surfactant level when
shorter chain ethylene oxide non-Tonics are used.
