Note: Descriptions are shown in the official language in which they were submitted.
~ Q 3 6
DETERGENT COMPOSITION
This invention relates to liquid compositions
containing solid particles suspended in a liquid phase which
is essentially non-aqueous and, at least pre~nm;n~ntly, is
nonionic surfactant.
The solid which is suspended may function as an
abrasive and/or may be included for some other purpose such
as to provide bleaching or detergency building when the
composition is mixed with water. Compositions of the
present invention include at least one hydratable salt in
the suspended solid material.
Non-aqueous compositions containing suspended
particulate solids are known, e.g. from GB 1292352
(Unilever). This discloses liquid detergent compositions
containing nonionic surfactant as the liquid phase, with
particulate water-soluble salts suspended in it. Most of
these compositions also contain some organic solvent other
than surfactant, usually mostly ethanol, as diluent and
thinning agent.
It is desirable that a composition should provide
stable suspension of the solid without however setting or
gelling to an excessively viscous state.
It is especially desirable to avoid setting to a
state which is excessively viscous and does not readily thin
203~
when shaken or otherwise subjected to shear.
We have found that the presence of hydratable salt
in a composition contributes to the suspending properties of
the composition, but excessive gelation may occur. We have
now found that non-hydratable salts can be used as a solid
diluent for hydratable salts and this can ameliorate
excessive gelling while still achieving suspen~i ng
properties.
Our GB 1292352 teaches that a small percentage of
a highly voluminous inorganic carrier material of submicron
size - fumed silica is suitable - may be included in a non-
aqueous liquid detergent composition. Such material
considerably improves the suspen~;ng properties and may be
used in compositions of this invention. However, the amount
of such material must be restricted. Too much of it leads
to excessive gelation of the composition.
We have found that the use of a combination of
hydratable and non-hydratable salts às the suspended solid
can allow adequate suspension to be achieved with less of
such submicron carrier than would be required in the
absence of hydratable salt(s) from the suspended solid.
This can ameliorate the tendency to gel into an undesirably
set state.
This invention provides a liquid, non-aqueous
composition comprising:
a liquid phase which is at least predominantly
nonionic surfactant in an amount of 25 to 75% of nonionic
surfactant by weight, having suspended therein
3 2 ~ ~ ~ 5 ~ ~
20 to 75% of solid particulate material with a
surface weighted mean particle size in the range 1 to 100
which comprises
i) from 5 to 45~ by weight of one or more salts
which form hydrate(s) stable at 20 C but are present in an
anhydrous or incompletely hydrated state, together with
ii) from 10 to 55~ by weight of one or more salts
which has no stable hydrate at 20 C,
which composition also contains 0.5 to 5% by
weight of carrier material having a surface weighted mean
particle size in the range from 1 to 900m~
all of the above percentages being by weight
based on the whole composition.
Since the carrier material has a mean particle
size below 1~, it is conveniently referred to as a n submicron
carrier". This material will generally be an oxide.
Compositions in accordance with the invention may
serve as various types of cleaning composition. One
possibility is a liquid detergent composition for use in
washing fabrics. In particular, though, compositions of
this invention may serve as abrasive cleaners, for instance
as hard surface cleaners. Such a formulation provides a
convenient method of delivering surfactant and desired
solids to a surface which is to be cleaned. Certain forms
of the invention are additionally advantageous in that the
non-aqueous liquid phase permits use of water-soluble solid
abrasive particles which can be readily rinsed from the
surface after cleaning.
B ~
2035~
A further advantage is that the solids present can
include a peroxygen bleach which will be in a stable
condition by reason of the non-aqueous environment.
Admixture of water at the time of use will then make the
bleach active.
As mentioned above, we have found that suspended
hydratable salt increases the suspending properties of the
composition and this effect adds to the suspending
properties brought about by submicron carrier material, if
any. By contrast, we have found that non-hydratable salts
do not enhance suspending properties - at least not as much
as do hydratable salts - but also do not increase the
tendency to gelation and setting. Non-hydratable salts are
thus able to function as a solid diluent for hydratable
salts.
A preferred additional constituent of compositions
of the present invention is 0.1 to 20~ by weight of an
organic solvent. The presence of such solvent is useful in
improving the ability of the compositions to remove a range
of soil from a surface. It may be preferred to avoid
hydroxylic solvents, or at any rate the lower (Cl to C6
alcohols). These may be oxidised at varying speeds by a
bleach system, if such a system is present.
Organic solvent does tend to cause a reduction in
suspending properties which must then be compensated by an
enhancement of the amount of carrier or hydratable salt.
The amount of nonionic surfactant must be in the
range 25 to 75% by weight of the composition. Preferably
~ o ~
the amount of nonionic surfactant is not more than 65%
better not more than 50% by weight of the composition. A
particularly preferred range is 35% to 49%. It is also
preferred that the amount of organic solvent, if any, is not
more than 8% and that the total amount of liquid phase does
not exceed 55% or possibly does not exceed even 49% of the
composition (all percentages being by weight based on the
whole composition).
This invention may be utilised in conjunction with
other expedients for ameliorating gelation while achieving
good suspension of solids. Notable are the incorporation of
polyvinylpyrrolidone or a derivative thereof as taught in
our European application EP 359491. Another possible
expedient is the incorporation of an organic acid, such as
alkyl benzene sulphonic acid.
Particle Size Measurements
Various techniques for measuring particle sizes
are known, but do not give results in precise agreement
because particles are not always spherical and do not always
have a Gaussian distribution of particle sizes. We have
found it convenient to measure particle sizes and size
distributions by light scattering measurements using a
Malvern Mastersizer (Trade Mark). This provides a
determination of surface weighted mean particle diameter and
we find this is an appropriate value of particle size to use
when studying sedimentation.
A description of surface weighted mean particle
2036i9~
size (also known as volume-surface weighted) is found in
chapter 4 of "Small Particle Statistics" by G Herdan,
Butterworths 1960.
For preferred forms of this invention the
submicron carrier will have a mean particle size which is
well below 1 micron regardless of the mean size definition
which is used, and the other suspended solid will have a
mean particle size of at least 1 micron with most
definitions of mean size.
Ingredients
The various essential and preferred ingredients of
the present invention will now be discussed in greater
detail.
Nonionic Surfactants
A considerable number of nonionic surfactants
exist and could be used for this invention. It is preferred
that the surfactant is a compound or mixture of compounds
produced by the condensation of alkylene oxide groups, which
are hydrophilic in nature, with an organic hydrophobic
compound which may be aliphatic, notably with a C8 to C2 2
alkyl chain or alkyl aromatic, notably with a C6 to C1 4
alkyl chain. The length of the hydrophilic or
polyoxyalkylene radical which is condensed with any
particular hydrophobic group can be adjusted to yield a
water-soluble compound having the desired degree of balance
between hydrophilic and hydrophobic elements. Particular
2036~g~
examples of nonionic surfactants include the condensation
product of aliphatic alcohols having from 8 to 22 carbon
atoms in either straight or branched chain configuration
with ethylene oxide, such as a coconut oil ethylene oxide
condensate having from 2 to 15 moles of ethylene oxide per
mole of coconut alcohol, and condensates of synthetic
primary or secondary alcohols having 8 to 15 carbon atoms
with 3 to 12 moles of ethylene oxide per mole of the
synthetic alcohol, and condensates of alkylphenols whose
alkyl group contains from 6 to 12 carbon atoms with 5 to 25
moles of ethylene oxide per mole of alkylphenol. Further
examples of nonionic surfactants are condensates of the
reaction product of ethylenediamine and propylene oxide with
ethylene oxide, the con~e~ates containing from 40 to 80~ of
polyoxyethylene radicals by weight and having a molecular
weight of from 5,000 to 11,000; block copolymers of ethylene
oxide and propylene oxide; tertiary amine oxides of
structure R3N0, where one group R is an alkyl group of 8 to
18 carbon atoms and the others are each methyl, ethyl or
hydroxyethyl groups, for instance dimethyldodecylamine
oxide; glycosides or polyglycosides etherified with at least
one C8 -C2 2 alkyl group or esterified with at least one C8-
C2 2 fatty acyl group; fatty acid alkylolamides; and alkylene
oxide condensates of fatty acid alkylolamides. Mixtures of
nonionic surfactant actives can be employed.
A particularly preferred category of nonionic
surfactants is ethoxylated alcohols. These may in
particular be derived from alcohols cont~; n; ng from 5 to 15
2036~3
carbon atoms and ethoxylated with an average of 5 to 10
ethylene oxide residues. Especially preferred is nonionic
surfactant derived from a mixture of alcohols mostly
containing 9 to 11 carbon atoms and having an average of 6
ethylene oxide residues.
We prefer that such a nonionic surfactant is
"topped" or "peaked", that is to say partially fractionated
in order to free it from unethoxylated alcohol which tends
to have an unpleasant odour.
Submicron Carrier
This material is a finely divided solid having a
mean primary particle size of less than one micron, for
instance in the range 1 to 900 m,u and preferably well below
900 m,u. Typically such solids will have an average surface
area of 50 to 500m2/g and a bulk density of 10 to 180
g/litre.
Suitable inorganic carrier materials are light,
highly voluminous metal and metalloid oxides including, for
example, silica, alumina, magnesia and ferric oxide and
mixtures thereof. These materials, particularly silicas,
may readily be obtained c~- ercially. Suitable silicas are
sold by Degussa under the Registered Trade Mark Aerosil and
by Cabot Corporation under the Registered Trade Mark
Cab-0-Sil.
Whilst any highly voluminous inorganic carrier
material having the specified physical characteristics may
be employed, it is preferred that the carrier material
~3~
should have a bulk density within the range of from 20 to
150g/l, more particularly from 30 to lOOg/l, and an average
surface area lying within the range of from 150 to 400m2/g.
The average surface area is indicative of particle size and
is defined as that measured by the Brenauer, Emmet and
Teller method. The preferred particle size and size
distribution of the inorganic carrier material is such that
substantially all of the particles of the carrier material
lie within a size range of 1 to 100 m~.
The amount of the submicron carrier material which
is used is preferably of the order of from 0.7 to 3~ by
weight of the composition.
Other Suspended Solid
This comprises the mixture of hydratable and non-
hydratable salts. These will preferably have an averageparticle size in the range of 1~ to 100~. Desirably though
they should have an average particle size smaller than 70,u
to avoid palpable grittiness. It is preferred that at
least 99% by weight of the particles should pass a 53~
sieve, with the average particle size being less than 50,u.
If the composition is intended to be abrasive, it
is preferred that at least the water-soluble salts should
have a relatively larger particle size than is preferred for
a composition intended for some other application such as
adding to water to make a fabric washing liquor.
Larger particle size is more appropriate for
abrasive properties but brings with it the problem that
203~
larger particles sediment at a faster rate and are more
difficult to maintain in a stable suspended state.
If a composition is not intended to be abrasive it
will be desirable, as with known fabric washing liquids, to
comminute the suspended particles to an average particle
size not exceeding lO,u better not exceeding 5,u.
If a composition is intended to be abrasive it is
preferred that the water-soluble salts should have an
average particle size exceeding 5~. The hydratable and the
non-hydratable salts may both satisfy this requirement.
More preferably the surface weighted mean particle
size of the water-soluble salt(s) present is between 10 and
25,u while the particle size distribution satisfies the
relationship:
D(v,0.9) - D(v,0.1)
1.5< < 3.0
D(v,0.5)
where D(v,0.5) is the median particle diameter, D(v,0.9) is
the upper decile diameter (i.e. 10% of particles are larger,
90% are smaller) and D(v,0.1) is the lower decile diameter.
An exception to this preference for particle sizes
larger than 5~u arises with the insoluble material calcite.
This is somewhat harder than water-soluble salts generally
are, and therefore is abrasive when used at smaller particle
sizes such as 2 to 5~.
The suspended solid can function as an abrasive.
As explained below, it may serve other functions. The size
203~33
11
range mentioned above is smaller than is customary in
liquid abrasive cleaners. It is advantageous in giving less
tendency to scratch and easier rinsing.
The suspended solid should preferably constitute
between 20 or 25% and 60% by weight of the composition.
More preferably it constitutes between 35 and 58% by weight
of the composition. In particularly preferred compositions
the total amount of suspended solid other than the submicron
carrier is at least 51% by weight of the composition.
Hydratable Salts
These are almost inevitably water-soluble. They
are used in a state which is incompletely hydrated. Ideally
they are anhydrous but a limited water content can be
tolerated.
A wide range of salts have hydrates at 20~C and
can be used. Organic salts such as citrates may possibly be
used, but inorganic salts will generally be used.
Examples of inorganic salts which have hydrates
are sodium carbonate, sodium tripolyphosphate, sodium
sulphate, sodium silicate in various forms, and the double
salt sodium sesquicarbonate. Sodium citrate and the organic
builder sodium nitrilotriacetate are both hydratable. It
will be appreciated that a number of these salts are known
detergency builders and can function as such when the
composition is eventually diluted with water during use.
The hydratable salt can be a peroxygen bleach.
Sodium perborate and sodium percarbonate are both
~03!~
12
hydratable salts. Sodium percarbonate is a perhydrate of
sodium carbonate and is further hydratable, analogously to
sodium carbonate itself.
The amount of hydratable salt is desirably
sufficient, in relation to the amount of voluminous
submicron inorganic carrier, to reduce sedimentation to a
very low level. Sedimentation can be observed as the volume
of clear liquid which separates at the top of a column of
the composition in a measuring cylinder. Preferred
compositions have not more than 1% separation after standing
for 10 days.
The amount of hydratable salt should not cause
gelling of the composition, or at any rate should allow a
reasonable storage time before serious gelling. The effect
of hydratable salts varies from one to another. Thus sodium
perborate and sodium carbonate both cause a greater
enhancement of suspen~; ng properties than an equal amount of
sodium tripolyphosphate, but the amount of them which can be
tolerated without gelling is also less.
It is preferred that the amount of hydratable salt
is 5 to 45% by weight of the composition. In an abrasive
composition the amount will generally be 5 to 25% by weight
of the composition and preferably is 8 to 20% by weight of
the composition.
Non-hydratable Salts
A number of water-insoluble non-hydratable salts
exist and can be used. Calcite is a preferred example.
2035~g3
13
Others are feldspar and dolomite.
Alternatively a water-soluble but non-hydratable,
salt can be used. This is advantageous in that the entire
composition can be water-soluble, and hence can be rinsed
away with water without leaving any insoluble residue. Such
complete solution on rinsing helps to avoid leaving any
undesired residue on cleaned surfaces. Salts which are
water-soluble but non-hydratable appear to be uncommon. The
salt envisaged for this use is sodium bicarbonate (whose
water-solubility is rather low).
The amount of non-hydratable salt is a balancing
quantity as required to increase the total amount of
suspended solid to the desired level but in accordance with
this invention it is at least 10% of the composition. More
preferably it is at least 10~ of the composition. It may
lie in the range 10 to 55% of the composition, with amounts
at the higher end of this range being appropriate for
abrasive compositions where the non-hydratable salt can
serve as abrasive material.
Solvent
Some form of organic solvent is desirably
included, but this does tend to cause a reduction in
suspending properties which must then be compensated by an
enhancement of the amount of carrier or hydratable salt.
Bleach Activator
When the hydratable salts include a peroxygen
~n36~3
-
14
bleach, a bleach activator may be included in the
composition. The preferred material is
tetraacetylethylenediamine (TAED). It is a fairly soft
organic solid and may dissolve, at least partially, in
organic solvent (if present) and nonionic surfactant. Its
density is about lg/ml and so is similar to that of the
surfactant and it appears to have little or no effect on the
properties of the composition.
Water Content
The composition should not contain sufficient
moisture to destroy its non-aqueous character. Depending on
the nature of the suspended solids some moisture content may
be acceptable.
Generally it is desirable that the quantity of
moisture in the composition, excluding any water bound as
water of hydration of suspended solids, should not exceed 5%
of the composition by weight. If a bleach is present this
free moisture content should preferably not exceed 1%,
better 0.1% of the composition by weight.
EXAMPLES
A number of compositions were prepared using a
standard preparative procedure.
In these Examples the nonionic surfactant was
C9 -Cl1 alcohol ethoxylated with average 6E0 and topped to
CA 02036~93 1998-07-21
remove residual unethoxylated alcohol. Organic solvent was
a paraffinic/alcohol solvent mixture. The carbon chains in
both solvents contain more than six carbo~ atoms. Inorganic
carrier was *Aerosil 380, a fumed silica available from
Degussa AG and which has a primary particle size of less
than 50m~u (the manufacturers quote 7 to 40m,u).
Sodium carbonate and tripolyphosphate were used in
forms which are almost anhydrous. Sodium perborate was
used as the so-called monohydrate which is actually an
anhydrous dimer of sodium borate and hydrogen peroxide.
As a preliminary step the various solid
constituents, except for the fumed silica, were comminuted
using a fine impact mill equipped with stud discs (Alpine
Process Technology Ltd, Model 160UPZ), so as to pass a 53
micron sieve. Particle sizes of the solids, as used in all
Examples, were as quoted in Example 1.
Preparation of the compositions was then carried
out in three stages. First the liquid base was prepared by
stirring together in a beaker the requisite amounts of
nonionic surfactant, organic solvent and perfume using a
Heidolph RZR50 paddle stirrer and then adding the fumed
silica (Aerosil 380). To complete the preparation of the
liquid base, after the addition of the silica, stirring was
continued for 10 minutes using a Silverson laboratory mixer
equipped with a special shaft with a hard coating on the
journal area, a medium emulsor screen and axial flow head.
Finally, the requisite quantities of the other solids were
stirred into the liquid base, using the paddle stirrer once
* denotes trade mark
203~ ~ ~3
- 16
again.
Samples of each composition were poured into
graduated cylinders and stored. By inspection of the
cylinders at intervals it was possible to observe the volume
of liquid above the volume still cont~i ni ng suspended solid.
This volume of separated liquid was expressed as a
percentage of the total volume of liquid. If it was seen
that a composition had obviously gelled to a set state, this
was noted.
In some instances the extent of gelation (setting)
of a composition was assessed in either or both of two ways.
One assessment procedure consisted of decanting off the
clear supernatant, if any, and then rating the firmness of
the residual sediment as a setting index on a scale from 1
to 6. The lowest number, 1, denotes a sediment which is
pourable without preli i n~ry agitation. The numbers 2 to 6
were assigned according to the number of strokes of a glass
tube needed to liquify the sediment to the point of being
just pourable. A setting index of 6 denotes a firmly set
composition.
The other assessment for gelation consisted of
resting the same glass tube, end-on, on the residual
sediment and observing whether in a short time it penetrated
fully (F) through the sediment to the bottom of the
graduated cylinder, partially (P) or not at all (N).
Example 1
Trial compositions were prepared by the above
2 0 3 ~
17
procedure, omitting the step of adding silica. The
ingredients of each composition are tabulated below. Also
set out below is the separation after varying periods of
time.
5 Formulations (% by weight)
A B C D
Nonionic surfactant 46 46 46 46
Sodium tripolyphosphate 54
Sodium bicarbonate 54
10 Sodium perborate 54
Calcite 54
Separation Data (%)
No. of days A B C D
O O O O O
1 gelled 7.5 0
2 gelled 13.5 0 1.5
4 gelled 17.0 0
gelled 3.5
7 gelled 18.0 1.0 6.5
-- 20 9 gelled 18.5 1.0 9.0
11 gelled 18.5 1.0
14 gelled 18.5 1.5
16 gelled 18.5 1.5
The densities and particle sizes of the suspended
solids were not identical. The densities, mean particle
~03~59~
_ 18
diameters, and theoretical initial sedimentation rates
(rates at the start of sedimentation, calculated using
Stokes equation modified by Steiner) were:
Surface-
weighted Calc. initial
mean sedimentation
Density diameter rate
(g/cc) (microns) (mm/day)
Sodium tripolyphosphate2.5419.4 18.3
Sodium bicarbonate 2.15 20.4 27.0
Sodium perborate 2.15 12.1 7.1
monohydrate
Calcite (Durcal 2) 2.7 4.0 1.2
By contrast, the actual results set out above show
a radical difference between the behaviour of the two types
of salts. The hydratable salts (tripolyphosphate and
perborate monohydrate) barely sediment, if at all, because
of gelling whereas the non-hydratable bicarbonate and
calcite do sediment.
Example 2
Trial compositions were prepared by the procedure
mentioned above. Some contained 46% liquid, others 60%
liquid. The formulations and the extent of separation after
varying periods of time are set out in the following Tables.
If it was noted that a composition had obviously gelled to a
set state, this was noted with the abbreviation "gld".
Assessments of gelation by the procedures
described above are also quoted in these Tables.
20~6~3
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2036~93
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2036~93
21
It can be seen from these results that at a level
of 40% solids it was not possible to use sodium perborate
monohydrate as the only suspended solid. At 54% solids
neither perborate nor tripolyphosphate could be incorporated
as sole suspended solid. If silica was used in sufficient
quantity to keep a suspension of bicarbonate stable, then
the compositions were found to gel to an unsatisfactory set
state.
By contrast, a composition of the following
10 formulation was prepared and tested.
% by weight
Nonionic surfactant 37.0
Organic solvent 5.0
Aerosil 380 2.5
15 Sodium bicarbonate 42.5
Sodium perborate 10.0
Perfume 1.5
Tetraacetylethylenediamine 1.5
Separation over 40 days was less than 1%. Setting
index was 2 and penetration was full. Thus there was
satisfactory suspension without excessive gelation.
Example 3
Compositions were prepared with ingredients as set
out in the following Table, in which separations after
periods of time are also quoted.
~03~
In m
U~ ~ U~ o o U~ o ~ o
~~ .................... . .. .
a~ Ln o ~ ~ ~ o ~ o o
C~ o o o
~ O O C~ o o
o ~ ~ U~ o o U~
., . ................. . ooooo
oo ~ o C'~ o
~ ~ ~ O O ~( ~1 ~
o U~ U~ o ~ o U~ o o
. ..... . . .
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~ , ~ .
o U~ o U~ o o o o U~
. ..... . . ...
c~ In o ~ a~ ~ o ~ ~ c~ C'l
m o o ~ o ~ o o o o U~ U~
o o c~ a~ ~ o ~ ~1 ~ ~ ~ C'i
o o ~ o In o In ~ o
m ~ ................. . . ...
a~ ~ o ~ ~ ~ o
In ~
C' o U o U~ O O U~ O
~, . ................. . . . . .
o~ ~ o - ~ ~ ~ o ~ ~ ~ ~ ~o
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(D D
-' ~D 1 ~ ~D 1
C ~D ~ ~
D ~1 ~ n
0 ~ C >1 ~ ~ /n
--' 4 a~
O
c tn n o, ~ c' ~)
(D ~ ~j (D o~ S ~ ~ D ~ ~
~I C ~ 0 C'~ ~
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E SZ -~ 1~ 4 (D rl.1 rl ~ ~ ~ 5~
o o
O dP S~ (D :~ O O O D ~ ~ :5 0 0 0 0 0 0 0 <~
2036S9~
_ 23
Compositions A, B, D and E show that increasing
silica enhances suspending properties.
Compositions C and D show that solvent slightly
reduces suspending properties.
Compositions E and F or D and H show that sodium
tripolyphosphate enhances suspending properties.
Comparison of composition H with composition G
shows that perborate enhances suspPn~ing properties (but
this is partly offset by the presence of solvent in
composition H).
Example 4
A composition was prepared using a fine calcite as
the non-hydratable salt. This abrasive is the same as the
calcite referred to in Example 1; it was Durcal 2 available
from Omya. A similar composition was prepared using sodium
carbonate and bicarbonate. The two formulations were as
follows:
20~6'~
24
B
Ingredient % by weight
Nonionic surfactant 38.5 38.8
Organic solvent 5.0 5.0
5 Perfume 0.5 0.5
Fumed silica 2.0 2.2
Abrasive Calcite (Durcal 2)39.0
Abrasive Sodium carbonate - 21.0
Abrasive Sodium bicarbonate - 21.0
10 Builder Sodium tripolyphosphate 3.5
Bleach Sodium perborate 10.0 10.0
TAED 1.5 1.5
100 . O 100 . O
On storage both of these compositions were found
to display only slight separation and thickening.
Both formulations A and B were tested for physical
cleaning efficiency in comparison with a current commercial
product having an aqueous liquid phase. The efficiency was
tested on the following soiled substrates.
1. Microcrystalline Wax on Perspex
Clear perspex sheet (ex ICI) was evenly sprayed
with petroleum spirit (fraction boiling between 100 and
120~C) saturated with microcrystalline wax (Mobil No 2360)
coloured with oil-soluble dye Fast Red 7B (CI 26050). After
spraying, the sheet was placed in an oven at 50~C to ensure
complete removal of the solvent. From the weight of the wax
- 2036~93
deposited on the sheet (ca 0.28g) and the surface area
(ca 280cm~2), the thickness of the layer was estimated as
about lO,u (assuming a value of 0.8 for the density of the
wax).
2. Calcium Stearate on Perspex
A solution of stearic acid in chloroform was
sprayed onto Perspex sheet as above (following the
established code of practice for safe handling of
chloroform). The plate was then repeatedly immersed in a
solution of calcium chloride and left to dry in an oven at
50~C. A damp tissue was used to wipe non-adherent salts
from the surface, leaving behind a thin hard layer of
calcium stearate.
3. Artificial Hard Bath Tub Soil (HBTS) on Enamel
Calcium stearate (75g), carbon black (0.5g Elftex
125) and isopropanol (250ml) were mixed together thoroughly
and dispersed by application of ultrasound. The dispersion
was diluted as necessary with isopropanol and sprayed in a
band down the centre of a white enamelled steel plate. The
plate was then placed in an oven preheated to 180~C for 20
minutes.
4. Shoe Polish on White Vinyl
Shoe polish was applied with a tissue in a band in
the middle of a white vinyl tile. The tile was aged
overnight before use.
203~
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26
5. Shoe Rubber on White Vinyl
Rubber was cut from the sole of a discarded shoe
and applied in close straight lines on a white vinyl tile to
give a band of rubber-marked tile.
Soil removal was determined using a Sheen ~
Instruments in-line scrubber equipped with a cellulose
sponge and operating at a relatively low surface pressure
_ t_ .
(28g cm~ 2 ) equivalent to light rubbing. Tests were carried
out by pre-moistening a clean sponge and applying a fixed
amount of formulation (lml). The number of strokes required
to completely remove the soil from a variety of
soil/substrate combinations was determined. Results are
presented in the Table below as:
No of strokes to remove
Efficiency Relative _ with cl- ~rcial product
to Commercial Product No of strokes to remove
with test formulation
---------- Formulation ---~
Soil/Substrate Commercial A B
Product
Microcrystalline wax/1.0 4.8 4.5
Perspex
Ca stearate/Perspex 1.0 - 1.5
HBTS/enamel 1.0 1.1 1.3
Shoe polish/vinyl 1.0 1.9 2.1
Shoe rubber/vinyl 1.0 18.3 42.3
The non-aqueous formulations clearly perform very
well on oily and waxy soils and exceptionally well on
2035S93
27
rubber-marked vinyl. Performance was similar on both
artificial bath scum soils consisting mainly of calcium
stearate on Perspex and enamel.
Application of an aqueous slurry of either
formulation to tea-stained unglazed white ceramic tiles
resulted in removal of about half the colour of the stain
(as determined by reflectance measurement) within about 1
minute. Increasing the contact time to 30 minutes did not
substantially increase the bleaching effect.
Example 5 ~'
The formulations A and B of the preceding Example
were compared with each other and the above-mentioned
~o~rcial product in a test of surface scratching. In this
test a clear polymethylmethacrylate surface was rubbed with
the formulation.
A Sheen in-line scrubber was used with pre-
moistened terry toweling operating over a range of surface
pressures (28-149g cm~2). The change in reflectance at 60~
from normal incidence was measured after 100 strokes (lOml
formulation) using a BYK Chemie 'Color Gloss' gloss meter
equipped with a multi-angle gloss sensing head.
The formulations were also compared on painted
wooden tiles using a Wool Industries Research Association
abrasion tester with pre-moistened terry toweling covered
heads operating at a surface pressure of 422g cm~ 2 ( 500
rubs, 20ml formulation).
It was found that both non-aqueous formulations
; ~ :
2035 ~ ~
28
caused less damage than the commercial product. On
polymethylmethacrylate, formulation B was superior to
formulation A.
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