Note: Descriptions are shown in the official language in which they were submitted.
IR 4681F
LINEAR VISCOELAS~IC AQUEOUS LIQUID
DETERGENT COMPOSITION, ESPECIALLY FOR
AUTOMATIC DISHWASHE~S OF
IMPROVED HIGH TEMPERATURE STA~ILITY
Background of the Invention
Liquid automatic dishwasher detergent compositions both
aqueous and nonaqueous, ha~e recently received much attention,
and the aqueous products have achieved commercial popularity.
The acceptance and popularity of the liqui~ ~ormulations
as compared to the more conventional powder products stems
from the con~enience and performance of the liquid products.
However, even the best of the currently a~ailable liquid
formulations still suffer from two major problems, product
phase instability and bottle residue, and to some extent cup
leakage ~rom the dispenser cup of the automatic dishwashing
machine.
Representative patent art in this area includes Rek, U.S.
Patent 4,556,504; Bush, et al., U.S. Patent 4,226,736; Ulrich,
U.S. Patent 4,431,559; Sabatelli, U.S. Patent 4,147,650;
Paucot, U.S. Patent 4,079,015; Leikhem, U.S. Patent 4,116,849;
Milora, U.S. Patent 4,521,332; Jones, U.S. Patent 4,597,889;
Heile, U.s. Patent 4,512,908; Laitem, U.S. Patent 4,753,748;
Sabatelli, U.S. Patent 3,579,455; Hynam, U.S. Patent
3,684,722. Other patents relating to thickened aqueous
detergent compositions include U.S. Patent 3,985,668; U.K.
Patent Applications GB 2,116, 19gA and GB 240,450~; U.S.
Patent 4,511,487; U.S. Patent 4,752,409 (Drapier, et al.);
2 ~
U.S. Patent 4,801,395 (Drapier, et al.); U.S. Patent 4,836,946
(Dixit); U.S. Patent 4,889,653 (Ahmed, et al.). Commonly
assigned co-pending patents include, for example, Serial No.
427,912 filed October 24, 1989; Serial No. 924,385, filed
October 29, 19~6; Serial No. 323,138, filed March 13, 1989;
Serial No. 328,716, filed March 27, 1989; Serial No. 323,137,
filed March 13, 1989; Serial No. 323,134, filed March 13,
1989.
The solubilizing effect of potassium salts on sodium
tripolyphosphate in aqueous detergent compositions is
described in U.S. Patent 3,720,621 (Smeets). U.S. Patent
4,836,948 discloses a viscoelastic gel detergent composition
characteriæed by its viscosity under low and high shear
conditions, pH, and steady state viscoelastic deformation
compliance. The composition requires the presence of a
polycarboxylate polymeric thickener, preferably a cross-linked
polyacrylic acid. The compositions of this patent also,
however, require a trivalent metal containing material,
especially an aluminum containing material such as alumina.
The compositions may further include a s~ructuring chelant
which may be a salt of carbonate, pyrophosphate or mixture
thereof, and preferably the potassium salts. The recently
issued U.S. Patent 4,859,358 discloses the incorporation of
metal salts of long chain hydroxy fatty acids, as anti-
tarnishing agents, in thickened aqueous automatic dishwashing
detergent compositions. The thickeners for these compositions
may be a high molecular weight polycarboxylate polymer, such
as those sold under the Carbopol trade name, and specific 600
2 ~
and 900 series resins are mentioned. It is also disclosed
that the compositions may include entrained gas, e.g. air,
bubbles to further ensure stability. Amounts of air in the
range of from about 1~ to about 20~, preferably from about 5
to 15~ by volume will lower the specific gravity of the
overall composition to within from about 5% more than to about
10~ le~s than, preferably from 1~ more than to 5~ less than,
the specific gravity of the aqueous phase. In Example III of
this patent, the specific gravity of the composition was
stated as 1.32 g/cm3. The compositions are not described as
being linear viscoelastic and as exemplified do not include
any potassium salts.
While the compositions disclosed in U. S. Patent
5,06~,553 provided a satisfactory solution to the problems of
phase instability and bottle residue, as well as cup leakage,
it has now been found that under some storage/handling
conditions and/or processing conditions, additional
improvements would be desirable. Specifically, if the
viscoelastic composition is subjected to repeated heating and
cooling cycles, growth of crystals and product thinning and/or
precipitate formation has been observed. Chemical analysis of
the precipitated crystals has shown that these crystals are
comprised predominantly of sodium pyrophosphate. In addition,
it appears that the crystals tend to become entangled with the
polymeric thickener which tendency is presumed to account for
the thinning out or aqueous phase separation which has been
observed in conjunction with crystal formation and
precipitation.
2 ,1,~ r~ a ~ ~ ~
Brief_Description of the Drawinqs
Figures 1-6 are rheograms, plotting elastic modulus G'
and viscous modulus G" as a function of applied strain, ~or
the compositions of Example 1, Formulations A, B, C, D, E and
F, respectively.
Summary of the Invention
According to the present invention there is provided an
improved aqueous liquid automatic dishwasher detergent
composition. The composition i9 characterized not only by its
linear viscoelastic behavior, substantially indefinite
stability against phase separation or settling of dissolved or
suspended particles under high and low temperature conditions,
low levels of bottle residue, relatively high bulk density,
and substantial absence of loosely bound water, but also by
its overall product consistency from batch to batch and run to
run and over a wide range of storage and aging conditions,
including superior aesthetics, freedom from fish-eyes, absence
of crystal formation and growth, and resistance to cup
leakage.
The present invention was accomplished based, in part, on
the discovery that by replacing part or all o~ the
tetrapotassium pyrophosphate (TKPP) with potassium
tripolyphosphate (KTPP), crystal growth can be inhihited and
product consistency can be improved and the linear
viscoelastic properties can be extended beyond that previously
achieved. Further improvements are obtained by utilizing more
highly cross-linked and branched, temperature stable and
bleach and salt compatible polymeric thickening agents.
Furthermore, by controlling the conditiolls o:E mixing the
ingredients of the compositions, and particularly the p~ and
temperature of the aqueous phase u~ed to form the aqueous
solution of the pol~meric thickener, formation of Eish-eyes
and el.imination of viscosity reductions with time can be
achieved.
Accordingly, in one aspect the present invention provides
an improved linear viscoelastic aqueous liquid automatic
dishwasher detergent composition comprising water, up to 2% by
weight of long chain fatty acid or salt thereof, optionally,
from 3.1 to 5~ by weight of low-foaming chlorine bleach
stable, water dispersible automatic dishwasher non- 90ap
organic detergent, from 10 to 35% by weight of alkali metal
detergent.builder salt, at least 50~ by weight of which is
potassium tripolyphosphate or potassium pyrophosphate and at
least 5% by weight of which is sodium tripolyphosphate, from 3
to 20~ by weight of a chlorine bleach compound, and at least
one cross-linked polycarboxylate thickening agent having a
molecular weight of at least 500,000, wherein the aqueous
phase includes both sodium and potassium ions a~ a K/Na weight
ratio of from 1/1 to 45/1~ The compositions preferably have
a bulk density of from 1.28 g/cm3 to 1.42 g/cm3.
In a preferred embodiment, the linear viscoelastic
aqueous liquid automatic dishwasher detergent comprises,
approximately, by weight,
(a) (i) 8 to 25~ potassium tripolyphosphate detergent
builder,
2 ~ 'h a
(ii) 2 to 10~ sodium tripolyphosphate cletergent
builder, at an (i)/(ii) weight ratio of from 1.~/1 to 10/1;
(b) 5 to 15% alkali metal sllicate;
(c) 1 to 6% alkali metal hydroxid.e;
(d) Optionally, 0.1 to 3~ chlorine bleach stable, water-
dispersible organic detergent active material;
(e) 0.05 to 1.5~ chlorine bleach stable foam depressant;
(f) chlorine bleach compound in an amount to provide
about 0.2 to 4~ of available chlorine;
(g) 0.1 to 2.0~ of at least one hydrophilic cross-linked
water insoluble polycarboxylate thickening agent having a
molecular weight of from 800,000 to 4,000,000 to provide said
linear viscoelastic property;
(h) 0.01 to 2.0~ of long chain fatty acid or a metal
salt of a long chain fatty acid as a physical stabilizer to
increase the physical stability of the composition;
(i) 0 to 10~ of a non-cross-linked polyacrylic acid
having a molecular weight in the range of from about 800 to
200,000; and
(j) water;
and wherein in the entire composition, the ratio, by weight,
of potassium to sodium i5 from 1.05/1 to 3/1.
In another aspect of the invention, a method for
preparing the aqueous linear viscoelastic composition is
provided. According to this aspect, the method comprises the
steps of
2 ~
I. (a) ~ully hydrating the cross-llnked
polycarbox~late thickener by slowly adding the thickener to
heated water while moderate agitating the mixture.
(b) slowly adding a neutralizing amount of caustic
soda to the mixture from (a) while continuing agitation to
obtain a dispersion of the neutralized thickener;
II. (c) forming an aqueous mixture of surface active
agents;
(d) heating the mixture in (c) to a temperature
higher than that of the heated water in (a) and mixing until a
homogeneous smooth premix is obtained;
III. (e) uniformly mixing alkali metal builder salts
with the dispersion (b),
(f) uniformly mixing the heated premix (d) with the
mixture (e),
(g) cooling the mixture (f) to a temperature above
the temperature of the heated ~ater in step (a), and
(h) adding bleach to the mixture (g).
In a preferred embodiment of the inventio~ process, the
pH of the aqueous slurry of the cross-linked polycarboxylate
thickener after the neutralization in step (b) and in each
succeeding step is maintained at a value of at least 11.
Detailed Description and Preferred Embodiments
The compositions of this invention are thickened aqueous
liquids containing various cleansing active ingredients,
detergent builder salts and other detergent adjuvants,
structuring and thickening agents and stabilizing components,
although some ingredients may serve more than one o~ these
functions.
The advantageous characteristics of the compositions of
this invention include physical stability, as manifested by
little or no phase separation, solid settling or viscosity
changes over time or resulting from exposure to low or high
temperatures, low bottle residue, low cup leakage, high
cleaning performance, e.g. low spotting and filming, dirt
residue removal, and consistency in product characteristics
and performance, and superior aesthetics. These
characteristics are believed to be attributed to several
interrelated factors such as low solids, i.e. undissolved
particulate content, product density and linear viscoelastic
rheology. These factors are, in turn, dependent on several
critical compositional components and processing conditions of
the formulations, namely, (a) the inclusion of a thickening
effective amount of a temperature, bleach and salt stable
cross-linked polymeric thickening agent having high water
absorption capacity, exemplified by cross-linked polyacrylic
acid, (2) inclusion of a physical stabilizing amount of a long
chain fatty acid or salt thereof, and (3) potassium ion to
sodium ion weight ratio K/Na in the range of from 1:1 to 45:1,
especially from 1:1 to 3:1, and preferably also (4) - (6):
(4) a product bulk density of at least 1.28 g/cc, especially
at least 1.32 g/cc, (5) hydrating the cross-linked polymeric
thickener with heated water, and (6) maintaining the pH of the
neutralized polymeric thickener at a pH of at least 11,
preferably at least 11.5.
2 ~ r~ ~1
In particular, the linear viscoelastic aqueous liquid
au~omatic dishwasher detergent compositions of this invention
will, at least in the preferred embodiments, satisfy each of
the following stability criteria over the aging temperature-
time schedule shown by the following Table A:
TABLE A
Aging Temperature Duration
(F) _ (Weeks)
Minimum Preferre
140 ~ 1 ~ 2
120 ~ 6 > 8
100 ~ 13 ~ 1~
Ambient ~ 24 , 24
More specifically, the compositions are considered stable if
each of the following stability criteria i9 ~atisfied for at
least the minimum number of weeks for each aging temperature
shown in Table A:
o no visible phase separation (i.e. no
solid/liquid separation)
o no significant change (e.g. less than 10~) in
viscosities, yield stress or other dynamic-mechanical
properties
o no crystal growth under repeated heating-
cooling cycles over a temperature range of at lea~t 7F to
140F
o no decolorization or significant color change.
In addition to the above stability criteria, the compositions
of this invention are further characterized by their low
bottle residue. Specifically, for the preferred cross-linked
polyacrylic acid thickened compositions of this invention,
~ 2 ~
bottle residues, llnder the usual use conditions, will be no
more than 6 to 8~, preferably no more than 4 to 5~, of the
original bottle contents, on a weight basis.
The polymeric thickening agents contribute to the
linear viscoelastic rheology of the invention compositions.
As used herein, "linear viscoelastlc~ or "linear
viscoelasticity" means that the elastic (storage) moduli (G')
and the viscous (loss) moduli (G") are both substantially
independent of strain, at least in an applied strain range of
from 0-50~, and preferably over an applied strain range of
from 0 to 80%. More specifically, a compositlon is considered
to be linear viscoelastic for purposes of this invention, if
over the strain range of 0-50% the elastic moduli G' has a
minimum value of 100 dynes/sq.cm., preferably at least 250
dynes/sq.cm., and varies less than 500 dynes/sq.cm.,
preferably less than 300 dynes/sq.cm., especially preferably
less than 100 dynes/s~.cm. Preferably, the minimum value of
G' and maximum variation of G' applies over the strain range
of 0 to 80%. Typically, the variation in loss moduli G" will
be less than that of G'. As a further characteristic of the
preferred linear viscoelastic compositions the ratio of G~/G'
(tan ~) is less than 1, preferably less than 0.8, bu~ more
than 0.05, preferably more than 0.2, a~ least over the strain
range of 0 to 50~, and preferably over the strain range of 0
to 80~. It should be noted in this regard that % strain is
shear strain xlO0.
By way of further explanation, the elastic (storage)
modulus G' i~ a measure of the energy stored and retrieved
2 ~
when a strain is applied to the composition while viscous
(loss) modulus G" is a measure of the amount of energy
dissipated as heat when strain is applied. Therefore, a value
of tan ~,
0.05 c tan ~ c 1,
preferably
0.2 < tan ~ ~ 0.8
means that the compositions will retain sufficient energy when
a stress or strain is applied, at least over the extent
expected to be encountered for products of this type, for
example, when poured from or shaken in the bottle, or stored
in the dishwasher detergent dispenser cup of an automatic
dishwashing machine, to return to its previous condition when
the stress or strain is removed. The compositions with tan
values in these ranges, therefore, will also have a high
cohesive property, namely, when a shear or strain is applied
to a portion of the composition to cause it to flow, the
surrounding portions will follow. As a result of this
cohesiveness of the linear viscoelastic characteristic, the
compositions will readily flow uniformly and homogeneously
from a bottle when the bottle is tilted, ~hereby contributing
to the physical (phase) stability of the formulation and the
low bottle residue (low product loss in the bottle) which
characterizes the invention co~lpositions. The linear
viscoelastic property also contributes to improved physical
stability against phase separation of any undissolved
suspended particles by providing a resistance to movement of
the particles due to the strain exerted by a particle on the
2 ~ 2 3
surrounding Eluid medium. Linear viscoelasticity also
contributes to the elimination of dripping of the contents
when the product is poured from a bottle and hence reduction
of formation of drops around the container mouth at the
conclusion of pouring the product from a container.
Also contributing to the physical stability and low
bottle residue of the invention compositions is the high
potassium to sodium ion ratios in the range of 1:1 to 45:1,
preferably 1:1 to 4:1, especially preferably from 1.05:1 to
3:1, for example 1.1:1, 1.2:1, 1.5:1, 2:1, or 2.5:1. At ~hese
ratios the solubility of the solid salt components, such as
detergent builder salts, bleach, alkali metal silicates, and
the like, is substantially increased since the presence of the
potassium (K+) ions requires less water of hydration than the
sodium (Na+) ions, such that more water i9 available to
dissolve these salt compounds. Therefore, all or nearly all
of the normally solid components are present dissolved in the
aqueous phase. Since there is none or only a very low
percentage, i.e. less than 5~, preferably less than 3~ by
weight, of suspended solids present in the formulation there
is no or only reduced tendency for undissolved particles to
settle out of the compositions causing, for example, formation
of hard masses of particles, which could result in high bottle
residues (i.e. loss of product). Furthermore, any undissolved
solids tend to be present in extremely small particle sizes,
usually colloidal or sub colloidal, such as 1 micron or less,
thereby further reducing the tendency for the undissolved
particles to settle. Since there are substantially no
3 ~ ~ ~3
undissolved solid particle~ of size in excess of 1 micron, the
invention products tend to be transparent or at least
translucent, depending, in part, on air bubble content.
A still further attribute of the invention
compositions contributi.ng to the overall product stability and
low bottle residue is the high water absorption capacity of
the cross-linked polyacrylic acid-type thickening agent. As a
result of this high water absorption capacity virtually all of
the aqueous vehicle component appears to be held tightly bound
to the polymer matrix. Therefore, there appears to be no or
substantially no free water present in the invention
compositions. This apparent absence of free water (as well as
the cohesiveness of the composition) is manifested by the
observation that when the composition i9 poured from a bottle
onto a piece of water absorbent filter paper virtually no
water is absorbed onto the filter paper over a period of at
least several hours or longer and, furthermore, the mass of
the linear viscoelastic material poured onto the filter paper
will retain its shape and structure. As a result of the
absence of loosely bound water, there is virtually no phase
separation between the aqueous phase and the polymeric matrix
or dissolved solid particles. This characteristic is
manifested by the fact that when the subject compositions are
subjected to centrifugation, e.g. at 1000 rpm for 30 minutes,
there is no phase separation and the composition remains
homogeneous. The preferred compositions have remained stable
for period in excess of 6 months and more.
In U. S. Patent 5,064,553 it was stated that to
maximize physical (phase) stability, the density of the
composition should be controlled such that the bulk density of
the liquid phase is approximately the same as the bulk density
of the entire composition, including the polymeric thickening
agent. This control and equalization of the densities was
achieved, according to our earlier invention, by providing the
composition with a bulk density of at least 1.32 g/cc. A
density of 1.42 g/cc is essentially equivalent to zero air
content.
It is important to note that the bulk density of the
product can be adjusted by controlling the degree of aeration,
as well as total solid content. Further, the dispersed air
bubbles also contribute to the viscoelastic property of the
product.
However, it has now been found that air bubble
incorporation i9 not required to achieve stabilization and, in
fact, we have been able to prepare stable thickened products
with densities as low as 1.28 g/cc. At densities below the
1.28 cc/g, however, the flowability of the product tends to be
degraded and the large air bubble content tends to cause the
composition to be too highly translucent or cloudy to opaque.
Therefore, the product density is preferably selected in the
range of 1.28 to 1.42 g/cc, especially 1.32 to 1.40 g/cc, and
most preferably from 1.35 to 1.40 g/cc. Within these ranges
air bubble incorporation is determined to achieve the desired
product aesthetic appearance and flow characteristics.
2 ~ ~ f~
It has previously been found in connection with
other types of thickened aqueous liquid, automatic dishwasher
detergent composltions that ayglomeration or escape of
incorporated air bubbles could be avoided by incorporating
certain surface active ingredients, especially higher fatty
acids and the salts thereof, such as stearic acid, behenic
- acid, palmitic acid, sodium stearate, aluminum stearate, and
the like.
Therefore, in the present invention, in order to
avoid stabilization of air bubbles which may become
incorporated into the compositions during no~nal processing,
such as during various mixing steps, is avoided by post-adding
the surface active ingredients to the remainder of the
composition, under low shear conditions using mixing devices
designed to minimize cavitation and vortex formation.
As will be described in greater detail below the
surface active ingredients present in the compositio~ will
include include anti-Eoaming agent (e.g. phosphate ester) and
higher fatty acid or salt thereof as a physical stabilizer and
optionally a detergent surface active cleaning agent.
Exemplary of the polycarboxylate type thickening
agents are cross-linked polyacrylic acid-type thickening
agents sold by B. F. Goodrich under their Carbopol trademark,
including both the 900 series resins, especially Carbopol 941,
which i9 the most ion-insensitive of this class of polymers,
and Carbopol 940 and Carbopol 934, and the 600 series resins,
especially Carbopol 614. The Carbopol 900 series resins are
hydrophilic high molecular weight, cross-linked linear acrylic
2~3~ 3
.
acid polymers haviny an average equivalent weight of 76, and
the general structure illustrated by the following formula:
~ H H
t--- C ~~~~~~~ f - - - - 1- -
H C
/ \\
HO O n.
Carbopol 941 has a molecular weight: oE 1,250,000; Carbopol 940
a molecular weight of 4,000,000 ancl Carbopol 93~ a molecular
weight of 3,000,000. The Carbopol 900 series resins are
cross-linked with polyalkenyl polyether, e.g. 1~ of a
polyallyl ether of sucrose having an average of 5.8 allyl
groups for each molecule of sucrose. The preparation of thls
class of cross-linked carboxylic pol~mers is described in U.S.
Patent 2,798,053. Further detailed information on the
Carbopol 900 series resins is available from B. F. Goodrich,
see, Eor example, the B. F. Goodrich catalog GC-67, Carbopol~
Water Soluble Resins.
In general, these thickening resins are preferably
copolymers of a water dispersible copolymer of an alpha-beta
monoethylenically unsaturated lower aliphatic carboxylic acid
cross-linked with a polyether of a polyol selected from oligo
saccharides, reduced derivatives thereof in which the carbonyl
group is converted to an alcohol group and pentaerythritol,
the hydroxyl groups of the polyol which are modified being
etherified with allyl groups, there being preferably at least
two such allyl groups per molecule.
These water-dispersible cross-linked thickening
resins as described in the aforementioned U.S. Patent
17
~ a~ 3
2,798,053 and which have been co~mercialized by B. F. ~oodrich
as the Carbopol 900 series resins are prepared from
essentially linear copol~ners. More recently, B. F. Goodrich
has introduced the Carbopol 600 series resin. These are high
molecular weight, non-linear polyacrylic acid cross-linked
with polyalkenyl ether. In addition to the non-linear or
branched nature of these resins, they are also believed to be
more highly cross-linked than the 9t)0 series resins and have
molecular weights between l,000,000 and 4,000,000. Mixtures
of two or more Carbopol resins can be used in the composition.
Most especially useful of the Carbopol 600 series
resins is Carbopol 614 which is the most chlorine bleach
stable of this class of thickening resins. Carbopol 614 is
also highly stable in the high alkalinity environment of the
preferred liquid automatic dishwasher detergent compositions
and is also high stable to any anticipated storage temperature
conditions from below freezing to elevated temperatures as
high as 120F, preferably 140F, and especiall~ 160F, for
periods of as long as several days to several weeks or months
or longer.
While the most favorable results have now been
achieved with Carbopol 614 polyacrylic resin, other linear or
branched cross-linked polycarboxylate-type thickening agents
can also be used in the compositions of this invention. As
used herein "polycarboxylate-type" refers to water-soluble
carboxyvinyl polymers of alpha,beta monoethylenically
unsaturated lower aliphatic carboxylic acids, which may be
linear or non-linear, and are exemplified by homopolymers of
18
2 l~
acrylic acid or methacrylic acid or water-dispersible or
water-soluble salts, esters or amides thereof, or water-
soluble copolymers of these acids or their salts, esters or
amides with each other or with one or more other ethylenically
unsaturated monomers, such as, for example, styrene, maleic
acid, maleic anhydride, 2-hydroxyethylacrylate, acrylonitrile,
vinyl acetate, ethylene, propylene, and the like, and which
have molecular weights of from 500,000 to 10,000,000 and are
cross-linked or interpolymerized witl1 a multi-vinyl or multi-
allelic functionalized cross-linking agent, especially with a
polyalkenyl ether of a polyhydric compound.
These homopolymers or copolymers are characterized
by their high molecular weight, in the range of from 500,000
to 10,000,000, preferably 750,000 to 5,000,000, especially
from 1,000,000 to 4,000,000, and by their water solubility,
generally at least to an extent of up to 5~ by weight, or
more, in water at 25C.
These thickening agents are used in their cross-
linked form wherein the cross-linking may be accomplished by
means known in the polymer arts, as by irradiation, or,
preferably, by the incorporation into the monomer mixture to
be polymerized of known chemical cross-linking monomeric
agents, typically polyunsaturated (e.g. diethylenically
unsaturated) monomers, such as, for example, divinylbenzene,
divinylether of diethylene glycol, N,N'-methylene-
bisacrylamide, polyalkenylpolyethers (such as described
above), and the like. Typically, amounts of cross-linking
agent to be incorporated in the final polymer may range from
19
0.01 to 5 percent, preferably from 0 05 to 2 percent, and
especially, preferably from 0.1 to 1.5 percent, by weight of
cross-linkiny agent to weight of total polymer. Generally,
those skilled in the art will recognize that the degree of
cross-linking should be sufficient to impart some coiling of
the otherwise generally linear or non-linear polymeric
compound while maintaining the cross-linked polymer at least
water dispersible and highly water-swellable in an ionia
aqueous medium.
The amount of the high molecular weight, cross-
linked polyacrylic acid or other high molecular weight,
hydrophilic cross-linked polycarboxylate thickening agent to
impart the desired rheological property of linear
viscoelasticity will generally be in the range of from 0.1 to
2~, preferably from 0.2 to 1.4~, by weight, based on the
weight of the composition, although the amount will depend OXl
the particular cross-linking agent, ionic strength of the
composition, hydroxyl donors and the like.
The compositions of this invention must include
sufficient amount of potassium ions and sodium ions to provide
a weight ratio of K/Na of at least 1:1, preferably from 1:1 to
45:1, especially from about 1:1 to 4:1, more preferably from
1.05:1 to 3:1, such as 1.1:1, 1.2:1, 1.5:1, or 2:1. When the
K/Na ratio is less than 1 there is insufficient solubility of
the normally solid ingredients whereas when the K/Na ratio is
more than 45, especially when it is greater than 3 or 4, the
product becomes too liquid and phase separation begins to
occur. When the K/Na ratios become much larger than 45, such
as in an all or mostly potassium formulation, the
polycarboxylate thickener loses its absorption capacity and
begins to salt out of the aqueous phase.
The potassium and sodium ions will be made present
in the compositions as the alkali metal cation of the
detergent builder salt(s), as well as alkali metal silicate or
alkali metal hydroxide components of the compositions. The
alkali metal cation may also be present in the compositions as
a component of anionic detergent, bleach or other ionizable
salt compound additive, e.g. alkali. metal carbonate. In
determining the K/Na weight ratios all of these sources should
be taken into consideration.
Specific examples of detergent builder salts lnclude
the polyphosphates, such as alkali metal pyrophosphate, alkali
metal tripolyphosphate, alkali metal metaphosphate, and the
like, for example, sodium or potassium tripolyphosphate
(hydrated or anhydrous), tetrasodium or tetrapotassium
pyrophosphate, sodium or potassium hexa-metaphosphate,
trisodium or tripotassium orthophosphate and the like, sodium
or potassium carbonate, sodium or potassium citrate, sodium or
potassium nitrilotriacetate, and the like.
In accordance one embodiment of with the present
invention, however, the detergent builder salts will be
comprised of mixtures of at least potassium tripolyphosphate
(KTPP) or potassium pyrophosphate and sodium tripolyphosphate
(NaTPP) (especially hexahydrate). Typical ratios of KTPP to
NaTPP are from 1.4:1 to 10:1, especially from 2:1 to 8:1. The
total amount of detergent builder salts is pre~erably from 10
v.
to 35~ by weight, more preferably from 15 to 35~, especially
from 18 to 30~ by weight of the composition. Of this total
amount of the detergent builders at least 50~ by weight
(preferably at least 8~ by weight of the composition) will be
5 KTPP and preferably at least 5% by weight (preferably at least
2% by weight of the composition) will be NaTPP. More
preferably, the alkali metal detergent builder salt will be
comprised of from 65 to 95% of ~TPP, especially 75 to 90% of
KTPP and from 5 to 35%, especially 10 to 25% of NaTPP. In
terms of the total composition, the amount of KTPP will be in
the range of from 8 to 25~, preferably 15 to 22% by weight,
and the amount of NaTPP will be in the range of from 2 to 10%,
preferably 3 to 8% by weight.
When other alkali metal detergent builder salts are
present in the formulation, they will usually be present in
amounts less than 5~ by weight based on the total composition
and, in any case, in amounts to maintain the K/Na ratios to
within the above described range, preferably from 1:1.1 to
1:3.
The linear viscoelastic compositions of this
invention may, and preferably will, contain a small, but
stabilizing e~fective amount of a long chain fatty acid or
monovalent or polyvalent salt thereoE. Although the manner by
which the fatty acid or salt contributes to the rheology and
stability of the composition has not been fully elucidated it
is hypothesized that it may Eunction as a hydrogen bonding
agent or cross-linking agent for the polymeric thickener.
2~ ,3
The preferred long chain Eatty acids are the higher
aliphatic fatty acids having from 10 to 50 carbon atoms, more
preferably from 12 to 40 carbon atoms, and especially
preferably from 14 to 40 carbon atoms, and most preferably 20
to 40, inclusive of the carbon atom of the carboxyl group of
the fatty acid. The aliphatic radical may be saturated or
unsaturated and may be straight or branched. Straight chain
saturated fatty acids are preferred. Mixtures of fatty acids
may be used, such as those derived from natural sources, such
as tallow fatty acid, coco fatty ac:id, soya fatty acid, etc.,
or from synthetic sources available from industrial
manufacturing processes.
Thus, examples of the fatty acids include, for
example, decanoic acid, dodecanoic acid, palmitic acid,
myristic acid, stearic acid, behenic acid, oleic acid,
eicosanoic acid, tallow fatty acid, coco fatty acid, soya
fatty acid, mixtures of these acids, etc. Stearic acid and
mixed fatty acids, e.g. stearic acid/palmitic acid, are
preferred.
It has, however, also recently been discovered by
some of us and others that further improvements in phase
stability, particularly under elevated temperature storage
conditions, and maintenance of product viscosity levels can be
obtained by using longer chain length fatty acids in the range
of from Cl8 to C40. Either individual or mixtures of these
longer chain length fatty acids can be used, however, the
average chain length should be in the range of from 20 to 32
carbon atoms, especially 24 to 30 carbon atoms and mixture of
2 ~ 3 ~ 5
fatty acids encompassing this range are preferred. Suitable
mixed fatty acids are commercially avallable, for instance
those sold under the trade name Syncrowax by Croda.
When the free acid form of the fatty acid is used
directly it will generally associate with the potassium and
sodium ions in the aqueous phase to form the corresponding
alkali metal fatty acid soap. ~owever, the fatty acid salts
may be directly added to the composition as sodium salt or
potassium salt, or as a polyvalent metal salt, although the
alkali metal salts of the fatty acids are preferred fatty acid
salts.
The preferred polyvalent metals are di- and tri-
valent metals of Groups IIA, IIB and III~, such as magnesium,
calcium, aluminium and zinc, although other polyvalent metals,
including those of Groups IIIA, IVA, VA, IB, IVB, VB, VIIB and
VIII of the Periodic Table of the Elements can also be used.
Specific examples of such other polyvalent metals include Ti,
Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb, Bi, etc. Generally,
~ the metals may be present in the divalent to pentavelent
20 state. Naturally, for use in automatic dishwashers, as well
as any other applications where the invention composition will
or may come into contact with articles used for the handling,
storage or serving of food products or which otherwise may
come into contact with or be consumed by people or animals,
the metal salt should be selected by taking into consideration
the toxicity of the metal. For this purpose, the alkali metal
and calcium and magnesium salts are especially higher
preferred as generally safe food additives.
24
s~
The amount of the fatty acid or fatty acid salt
stabilizer to achieve the desired enhancement oE physical
stability will depend on such factors as the nature of the
fatty acid or its salt, the nature and amount of the
thickening agent, detergent active compound, inorganic salts,
other ingredients, as well as the anticipated storage and
shipping conditions.
Generally, however, amounts of the fatty acid or
fatty aeid salt stabilizing agents in the range of from 0.02
to 2~ preferably 0.04 to 1~, more preferably from 0.06 to
0.8%, especially preferably from 0.08 to 0.4~, provide a long
term stability and absence of phase separation upon standing
or during transport at both low and elevated temperatures as
are required for a commercially aeeeptable produet.
Depending on the amounts, proportions and types of
fatty aeid physieal stabilizers and polyaerylie aeid-type
thiekening agents, the addition of the fatty aeid or salt not
only inereases physical stability but also provides a
simultaneous increase in apparent viseosity. Amounts of fatty
aeid or salt to polymerie thiekening agent in the range of
from 0.08 - 0.4 weight percent fatty aeid and salt from 0.4 -
1.5 weight pereent polymerie thiekening agent are usually
suffieient to provide these simultaneous benefits and,
therefore, the use of these ingredients in these amounts is
more preferred.
In order to achieve the desired benefit from the
fatty acid or fatty acid salt stabilizer, without
stabilization of excess ineorporated air bubbles and
~ f3 r~
consequent e~cessive lowering of the product bulk density, the
fatty acid or salt should be post-added to the formulation,
preferably together with the other surface active ingredients,
including detergent active compound and anti-foaming agent,
when present. These surface active ingredients are preferably
added as an emulsion in water wherein the emulsified oily or
Eatty materials are finely and homogeneously dispersed
throughtout the aqueous phase. To achieve the desired fine
emulsification of the fatty acid or fatty acid salt and other
surface active ingredients, it is usually necessary to heat
the emulsion (or preheat the water) to an elevated temperature
near the melting temperature of the fatty acid or its salt.
For example, for stearic acid having a melting point of 68 -
69C, a temperature in the range of between 50C and 70C will
be used. For lauric acid (m.p.=47C) an elevated temperature
of 35 to 50C can be used.
Foam inhibition i important to increase dishwasher
machine efficiency and minimi7e destabilizing effects which
might occur due to the presence of excess foam within the
washer during use. Foam may be reduced by suitable selection
of the type and/or amount of detergent active material, the
main foam-producing component. The degree of foam is also
somewhat dependent on the hardness of the wash water in the
machine whereby suitable adjustment of the proportions of the
builder salts, such as NaTPP which has a water softening
effect, may aid in providing a degree of foam inhibition.
However, it is generally preferred to include a chlorine
26
~ 3
bleach s~able foam depressant or inhibitor. Particularly
effective are the alkyl phosphoric acid esters of the formula
O
HO---P---R
OR
and especially the alkyl acid phosphate esters of the formula
l l
HO----P----OR
OR
In the above formulas, one or both E~ groups in each type of
ester may represent independently a Cl2-C20 alkyl group. The
ethoxylated derivatives of each type of ester, for example,
the condensation products of one mole of ester with from 1 to
10 moles, preferably 2 to 6 moles, more preferably 3 or 4
moles, ethylene oxide can also be used. Some examples of the
foregoing are commercially available, such as the products SAP
from Hooker and LPKN-158 from Knapsack. Mixtures of the two
types, or any other chlorine bleach stable types, or mixtures
of mono- and di-esters of the same type, may be employed.
Especially preferred is a mixture of mono- and di-CI6-Cl8 alkyl
acid phosphate esters such as monostearyl/distearyl acid
phosphates 1.2/1, and the 3 to 4 mole ethylene oxide
condensates thereof. When employed, proportions of 0.05 to
1.5 weight percent, preferably 0.1 to 0.5 weight percent, of
foam depressant in the composition is typical, the weight
ratio of detergent active component (d) to foam depressant (e)
generally ranging from about 10:1 to 1:1 and preferably 5:1 to
1:1. Other defoamers which may be used include, for example,
27
2~ ~elB~r~
the known sillcones, such as avail~ble from Dow Chemicals. In
addition, it is an advantageous Eeature oE this invention that
many of the stabilizing salts, such as the stearate salts, for
example, aluminum stearate, when included, are also effective
as foam killers.
Although any chlorine bleach compound may be
employed in the compositions of this invention, such as
dichloroisocyanurate, dichloro-dimethyl hydantoin, or
chlorinated TSP, alkali metal or alkaline earth metal, e.g.
potassium, lithium, magnesium and especially sodium,
hypochlorite is preferred. The composition should contains
sufficient amount of chlorine bleach compound to provide 0.2
to 4.0~ by weight of available chlorine, as determined, for
example, by acidification of 100 parts of the composition with
excess hydrochloric acid. A solution containing 0.2 to 4.0%
by weight of sodium hypochlorite contains or provides roughly
the same percentage of available chlorine. 0.8 to 1.6~ by
weight of available chlorine is especially preferred~ For
example, sodium hypochlorite (NaOC1) sol~ltion of from 11 to
13~ available chlorine in amounts of 3 to 20%, preferably 7 to
12~, can be advantageously used.
Another surprising and unexpected benefit and
advantage of the preferred Carbopol thickened compositions of
this invention is the essentially total masking of any
chlorine bleach odor which is characteris~ic of, for example,
the prior known clay thickened products. By virtue of the
masking of chlorine bleach odor, it has been found that the
subject compositions can be blended with substantially lower
i3 i~ ~
amounts of fragrance, e.g. lemon oil fragrance, to achieve the
same or superior olfactory sensation for the consumer. For
instance, as little as 0.05% of lemon fragrance will have the
same effect as 0.12~ in clay thickened products.
Furthermore, the addltion of fragrance does not
adversely affect the stability criteria, as previously
deFined, such as viscosity or phase stability, of the
compositions.
Detergent active material which are optionally
useful herein should be low-foaming and stable in the presence
of chlorine bleach, when present, especially hypochlorite
bleach, and for this purpose those oE the organic anionic,
nonionic, amine oxide, phosphine oxide, sulphoxide or betaine
water dispersible surfactant types are preferred, the first
mentioned anionics being most preferred. Particularly
preferred surfactants herein are the linear or branched alkali
metal mono- and/or di-(C8-CI4) alkyl diphenyl oxide mono- and/or
di-sulphates, commercially available for example as DOWFAX
(registered trademark) 3B-2 and DOWFAX 2A-1. In addition, the
surfactant should be compatible with the other ingredients of
the composition. Other suitable organic anionic, non-soap
surfactants include the primary alkylsulphates,
alkylsulphonates, alkylarylsulphonates and sec.-
alkylsulphates, Examples include sodium C~O-Cl8 alkylsulphates
such as sodium dodecylsulphate and sodium tallow
alcoholsulphate; sodium ClO- Cl8 alkanesulphonates such as sodium
hexadecyl-1-sulphonate and sodium Cl2-CI8
alkylbenzenesulphonates such as sodium
29
dodecylbenzenesulphonates. The corresponding pota3sium salts
may also be employed.
As other suitable surfactants or detergents, the
amine oxide surfactants are typlcally of the structure R2RINO,
in which each R represents a lower alkyl group, for instance,
methyl, and Rl represents a long chain alkyl group having from
8 to 22 carbon atoms, for instance a lauryl, myristyl,
palmityl or cetyl group. Instead of an amine oxide, a
corresponding surfactant phosphine oxide R2R~PO or sulphoxide
RRISO can be employed. Betaine surfactants are typically of
the structure R2RINtR"COO-, in which each R represents a lower
alkylene group having from 1 to 5 carbon atoms. Specific
examples of these surfactants include lauryl-dimethylamine
oxide, myristyl-dimethylamine oxide, the corresponding
phosphine oxides and sulphoxides, and the corresponding
betaines, including dodecyldimethylammonium acetate,
tetradecyldiethylammonium pentanoate,
hexadecyldimethylammonium hexanoate and the like. For
biodegradabili~y, the alkyl groups in these surfactants should
be linear, and such compounds are preferred.
Surfactants of the foregoing type, all well known in
the art, are described, for example, in U.S. Patents 3,985,668
and 4,271,030. If chlorine bleach i9 not used then any of the
well known low-foaming nonionic surfactants ~uch as
alkoxylated fatty alcohols, e.g. mixed ethylene oxide-
propylene oxide condensates of C~-C22 fatty alcohols can also be
used.
3 r~
The chlorine bleach stable, ~ater dispersible
organic detergent-active material (sur~actant) will normally
be present in the composition in minor amounts, generally 1%
by weight of the composition, although smaller or larger
amounts, such as up to 5~, such as from 0.1 to 5~, preferably
from 0.3 or 0.4 to 3% by weight of the composition, may be
used.
Alkali metal (e.g. potassium or sodium) silicate,
which provides alkalinity and protection of hard surfaces,
such as fine china glaze and pattern, is generally employed in
an amount ranging from 5 to 20 weight percent, preferably 5 to
15 weight percent, more preferably 8 to 12~ in the
composition. The sodium or potassium silicate is generally
added in the form of an a~ueous solution, preferably having
Na2O:SiO2 or K2O: SiO2 ratio of 1:1.3 to 1:2.8, especially
preferably 1:2.0 to 1:2.6. At this point, it should be
mentioned that many of the other components of this
composition, especially alkali metal hydroxide and bleach, are
also often added in the form of a preliminary prepared aqueous
dispersion or solution. However, unless otherwise noted, when
amounts of a particular ingredient are given, the reference i3
to an active ingredient basis, i.e. does not include the
aqueous carrier.
In addition to the detergent active surfactant, foam
inhibitor, alkali metal silicate corrosion inhibitor, and
detergent builder salts, which all contribute to the cleaning
performance, it is also known that the effectiveness of the
liquid automatic dishwasher detergent compositions is related
to the alkalinity, and particularly to moderate to high
alkalinity levels. Accordingly, the composition of this
invention will have pH values of at least 9.5, preferably at
least 11 to as high as 14, generally up to 13 or more, and,
when added to the aqueous wash bath at a typical concentration
level of 10 grams per liter, will provide a pH in the wash
bath of at least 9, preferably at least about 10, such as
10.5, 11, 11.5 or 12 or more.
The alkalinity will be achieved, in part, b~ the
lakli metal ions contributed by the alkali metal detergent
builder salts, e.g. sodium tripolyphosphate, potassium
tripolyphosphate, and alkali metal silicate, however, it i9
usually necessary to include alkali metal hydroxide, e.g. NaOH
or KOH, to achieve the desired high alkalinity. Amounts of
alkali metal hydroxide in the range of from 0.5 to 8%,
preferably from 1 to 6~, more preferably from 1.2 to 4%, by
weight of the composition will be sufficient to achieve the
desired p~ level and/or to adju~t the K/Na weight ratio.
While as stated above, high alkalinity is desired
with regard to improved cleaning performance, it has now
additionally been discovered that the pH of the composition
during processing i9 highly important for product stability,
e.g. viscosity, and bleach stability and phase stability.
Specifically, it has been found that, especially for the
Carbopol class of thickening agents, the amount of basic
neutralizing agent, preferably NaOH, should be sufficient to
provide the neutralized thickening agent with a pH of at least
11, preferably at least 11.5. Furthermore, these high
32
t,~ f:~ ~J ~,j
alkalinity leve]s should be maintained throughout the product
formulation steps, namely, the pH value of at least 11,
preferably at least 11.5, should be maintained during the
successi~e additions of the other ingredients of the
competition.
As will be shown by the examples given below, if the
pH drops to a lower value, there is a loss in viscosity, as
well as stability (as manifested by liquid phase separation)
over time.
Other alkali metal salts, such as alkali metal
carbonate may also be present in the compositions in minor
amounts, for example from 0 to 4~, preferably 0 to 2~, by
weight of the composition.
Another often beneficial additive for the present
liquid automatic dishwasher detergent compositions is a
relatively low molecular weight, non-croRs-linked polyacrylic
acid or neutralized with caustic, such as the commercial
product ~crysol LMW=45N, which has a molecular weight of
4,500. The low m.w. polyacrylic acids can provide additional
thickening characteristics but are primarily introduced for
their ability to function as a builder or chelating agent. In
this capacity, the low m.w~ polyacrylic acids can contribute
to reduced spotting or streaking and reduced filming on
dishes, glassware, pots, pans, and other utensils and
appliances.
Generally, a suitable molecular weight ranges for
the non-cross-linked polyacrylic acid is from aoo to 200,000,
preferably 1000 to 150,000, especially from 2,000 to 100,000.
When present in the formulation, the non-cross-linked
polyacrylic acid can be used in amounts up to 10% by weight,
preferably from 1~ to 8~ by weight, especially 2 to 6~ by
weight of the composition.
Other conventional ingredients may be included in
these compositions in small amounts, generally less than about
3 weight percent, such as perfume, hydrotropic agents such as
the sodium benzene, toluene, xylene and cumene sulphonates,
preservatives, dyestuffs and pigments and the like, all of
course being stable to chlorine bleach compound and high
alkalinity. Especially preferred for coloring are the
chlorinated phthalocyanines and polysulphides of
aluminosilicate which provide, respectively, pleasing green
and blue tints. To achieve stable yellow colored products,
the bleach stable mixed dyes C.I. Direct Yellow 2~ (C.I.
19555) or C.I. Direct Yellow 2g (C.I. 19556) can be added to
the compositions. These colors meet stability criteria
described in Table A. TiO2 may be employed for whitening or
neutralizing off-shades.
Although for the reasons previously discussed
excessive air bubbles are not often desirable in the invention
compositions, depending on the amounts of dissolved solids and
liquid phase densities, incorporation of small amounts of
finely divided air bubbles, generally up to 10~ by volume,
preferably up to 4% by volume, more preferably up to about 2
by volume, can be incorporated to adjust the visual
appearance, product density and flowability. The incorporated
air bubbles should be finely divided, such as up to 100
34
r j
I
microns in diameter, preferably from 20 to 40 microns in
diameter. Other inert gases can also be used, such as
nitrogen, carbon dioxlde, helium, oxygen, etc.
The amount of water contained in these compositions
should, of course, be neither so high as to produce unduly low
viscosity and fluidity, nor so low as to produce unduly high
viscosity and low flowability, linear viscoelastic propertles
in either case being diminished or destroyed by increasing tan
1. Such amount i9 readily determined by routine
experimentation in any particular instance, and generally will
range from 30 to 75 weight percent, preferably 35 to 65 weight
percent. Preferably, the water should also be deionized or
softened.
The manner of formulating the invention compositions
is also important. As discussed above, the order of mixing
the ingredients as well as the manner in which the mixing is
performed will generally have a significant effect on the
properties of the composition, and in particular on product
density (by incorporation of more or less air), viscosity and
physical stability (e.g. phase separation). Thus, according
to the preferred practice of this in~ention the compositions
are prepared by forming a dispersion of the polycarboxylate
type thickener in heated water, e.g. 35 to 60C (95 to 140F~,
preferably 40C to 50C (10~ to 122F), under moderate to high
shear conditions, neutralizing the dissolved polymer to a pH
of at least 11, preferably at least 11.5, such as from 11.5 to
13.0, to cause gelation. After transferring the thickener
dispersion to a main mixing tank processing is continued by
2 ~r)f!~J'i~
introduclng, while continuing mixing, the cletergent builder
salts, alkali metal silicates, chlorine bleach compound and
remaining detergent additives, including any previously unused
alkali metal hydroxide, if any, other than the surface-active
compounds. A11 oE the additional ingredients can be added
simultaneously or sequentially. Preferably, the ingredients
are added sequentially, wi.th mixing continued for from 2 to 10
minutes for each ingredient, although it is not necessary to
complete the addition of one ingredient before beginning to
add the next ingredient. Furthermore, one or more of these
ingredients can be divided into portions and added at
different times. These mi~ing steps should also be performed
under moderate to high shear rates to achieve complete and
uniform mixing. These additional ingredient mixing steps may
be carried out at room temperature, but preferably the
elevated temperature of the thickener slurry is maintained.
The composition may be allowed to age, if necessary, to cause
dissolved or dispersed air to dissipate out of the
composition.
The remaining surface active ingredients, including
the anti-foaming agent, optionally, organic detergent
compound, and fatty acid or fatty acid salt stabilizer is
post-added to the previously formed mixture in the form of an
aqueous emulsion (using from 1 to 10%, preferably from 2 to 4
of the total water added to the composition other than water
added as carrier for other ingredients or water of hydration)
which is pre-heated to a temperature in the range of from Tm-5
to Tm+20, preferably from Tm to Tm~10, where Tm is the melting
P~ $ ~ o fi~
point temperature of the Eatty acld or fatty ac~d salt. For
the stearic acid stabilizer the heating temperature is in the
range of 150 to 170F (65 to 77C). For the high chain length
fatty acids and mixtures Cl8-C36, correspondingly higher
temperatures may be used, such as from 160 to 200F (ca. 70 to
95C). However, if care is taken to avoid excessive air bubble
incorporation during the gelation step or during the mixing of
the detergent bullder salts and other additives, for example,
by operating under vacuum, or using low shearing conditions,
10 or special mixing apparatus, etc., the order of addition of
the surface active ingredients should be less important.
In accordance with an especially preferred
embodiment, the thickened linear viscoelastic aqueous
automatic dishwasher detergent composition of this invention
15 includes, on a weight basis:
(a) (i) 8 to 25~, preferably 10 to 20%, potassium
tripolyphosphate detergent builder;
(ii) 2 to 10~, preferably 4 to 8~, sodium
tripolyphosphate detergent builder, at an (i)/(ii) weight
20 ratio of from 1.4/1 to 10/1, preferably 2/1 to 6/1;
(b) 5 to 15, preferably 8 to 12~, alkali metal
silicate;
(c) 1 to 6~, preferably 1.2 to 4~, alkali metal
hydroxide;
(d) 0 to 5~, preferably 0.1 to 3~, chlorine bleach
stable, water-dispersible, low-foaming organic detergent
active material, preferably non-soap anionic detergent;
2~3~ 3
(e) 0 to 1.5~, preferably 0.~ to 0.5%, chlorine
bleach stable foam depressant;
(f) chlorine hleach compound in an amount to
provide 0.2 to 4~, preferably 0.8 to 1.6~, of available
chlorine;
~ g) at least one non-linear, water-dispersible
polyacrylic acid thickening agent comprising at least one high
molecular weight hydrophilic polycarboxylate having a
molecular weight of from 750,000 to 4,000,000, preferably
800,000 to 3,000,000, in an amount to provide a linear
viscoelasticity to the formulation, preferably from 0.2 to 2%,
especially preferably from 0.4 to 1.5~, more preferably from
0.4 to 1.0~;
(h) a long chain fatty acid or a metal salt of a
long chain fatty acid in an amount effective to increase the
physical stability of the compositions, preferably from 0.02
to 0.4~, more preferably from 0.1 to 0.3%;
(i~ 0 to 10~, preferably 1 to 8~, especially 2 to
6~ of non-cross-linked polyacrylic acid having a molecular
weight in the range of from 800 to 200,000, preferably 1000 to
150,000, especially 2,000 to 100,000; and
(j) balance water, preferably from about 30 to 75~,
more preferably from 35 to 65~; and wherein in the entire
composition the ratio, by weight, of potassium ions to sodium
ions is from 1.05/1 to 3/1 or 4/1, preferably from 1.1/1 to
2.5/1. The compositions may also have an amount of air
incorporated therein such that the bulk density of the
38
~7~3 'J;~,~
composition is from 1.28 to 1.42 ~/cc, preferably Erom ~.32 to
1.42 g/cc, more preEerably from 1.35 to 1.~0 g/cc.
The compositions will be supplied to the consumer in
suitable dispenser containers preferably formed of molded
plastic, especlally polyolefin plastic, and most preferably
opaque or translucent polyethylene, for which the invention
compositions appear to have particularly favorable slip
characteristics. In addition to their linear viscoelastic
character, the compositions of this invention rnay also be
characterized as pseudoplastic gels (non-thixotropic) which
are typically near the borderline between liquid and solid
viscoelastic gel, depending, for example, on the amount of the
polymeric thickener. The invention compositions can be
readily poured from their containers without any shaking or
squeezing, i.e. have a sufficiently low yield stress value to
flow under their own weight (gravity), although squee~able
containers are often convenient and accepted by the consumer
for gel-like products.
The liquid a~ueous linear viscoelastic automatic
dishwasher compositions of this invention are readily employed
in know manner for washing dishes, other kitchen utensils and
the like in an automatic dishwasher, provided with a suitable
detergent dispenser, in an aqueous wash bath containing an
effective amount of the composition, generally sufficient to
fill or partially fill the automatic dispenser cup of the
particular machine being used.
The invention also provides a method for cleaning
dishware in an automatic dishwashing machine with an aqueous
39
~ ~ !') rl ~ ~r~ I j
wash bath containing an effective amount of the liquid linear
viscoelastic automatic dishwasher detergent composition as
described above. The composition can be readily poured from
the polyethylene container with little or no squeezing or
S shaking into the dispensing cup of t:he automatic dishwashing
machine and will be sufficiently vicscous and cohesive to
remain ~ecurely within the dispensing cup until shear forces
are again applied thereto, such as hy the water spray from the
dishwashing machine.
The invention may be put into practice in various
ways and a number of specific embodiments will be described to
illustrate the invention with reference to the accompanying
examples.
All amounts and proportions referred to herein are
by weight of the composition unless otherwise indicated.
Example 1- The following formulations A-F were prepared as described
below:
~0
Table 1
FORMULATION --~- __ c _ - -
ING~DIENT A B C D E F'
l __ _.~. _. ~ . ___ _~ ... ._ l
I Water Q.A Q.A Q.A Q.A Q.A Q.A
¦ Carbopol 941 0.9 - _
¦ Carbopol 940 ~ 0.9 ~
I . . _ _ . ._ _ .. _ _
I Carbopol 614 0.9 0.9 0.9 0.9
¦ NaOEI (50~) 2.4 _ _ 4.5 4.0 4.5 4.5
Na-SIlicate (47.5~)(-1:2.4) 21 -21 -20.83-- 20.8-3 20.83 20.83
TKPP 15 15
. ~ _ I .... _ . . _ --
KTPP 20.35 20.35 13 20.35
. . .... .
NaTPP (anhydrous) 13 135.26 5.26 3 5.26
DOWFAX3B2 1 0.80.8 0.8 0.8 0.8
LPKN (anti-foaming agent) 0.16 0.16 ¦ 0.16 0.16 0,16 0.16
Fatty acid O.10~ 0.20~ 0.15r--- 0.15Z 0.152 ~
Bleach (13.1~) 8.1 11.1 10.13 10.13 10.13 10.13
Grapthol green 0.0025 0.003 0.003 0.003 0.003
CI Direct Yellow 28 _ 0.003
Air (Vol. ~) approx. 2 2 2 2 2 2
_ ~ ____
Acrysol LMW 45-N (45.0~) 4.4
_ , _
Highlights (~ragrance) 0.05 0.05 0.05 0.05
K/Na 0.98 0.98 1.61 1.61 i.17 1.61
-
Density 1.35 1.37 1.37 1.37 1.28 1.37
_
Stability ambient 8 wks a wks 24 wks 24 wks 12 wks 4 wks
Stability ioooF 2 wks 2 wks_ 20 wks 8 wks 4 wks
Stability 120F 8 wks 8 wks 4 wk
Stability 140F __ _2 wks 2 wks 2 wks
Crystal growth (100F) Yes YesNo No No
_ . , _. _ __ , . ~ r
Rheogram Flg. 1 Flg. 2 Fig. 3 Flg. 4 Flg. 5 Flg. 6
_ _ ... __ _ .___
Formulations A, B, C, D, E and F are prepared by first
forming a unifonm dispersion of the Carbopol 614 or 940
thickener in about 97~ of the water of the total formula
water. The Carbopol i~ slowly added by sprinkling it into the
vortex of previously colored deionized water preheated to a
. . _
2 stearic acid
I SyncroWax C2~2~
3 Syncrowax Cls36
- 41
2 ,~,~ r~
temperature of 105F using a mixer equipped with a premier
blade, with agitation set at a medium shear rate, as
recommended by the manufacturer. After mixing for about 15
minutes, the dispersion is then neutralized by addition, under
the same mixing, of the caustic soda (50~ NaOH) component
until a thickened product of gel-like consistency is formed
(about 10 minutes).
To the resulting gelled dispersion the silicate, sodium
tripolyphosphate (NaTPP), tetrapotassium pyrophosphate (TKPP),
10 or potassium tripolyphosphate (KTPP), the surfactant emulsion
(described below) and bleach and color, added sequentially, in
the order stated, with the mixing continued at medium shear
for several minutes before adding the next ingredient. After
the addition of the surfactant emulsion (at 160F), the mixture
15 is cooled to from 90-95F before the bleach is added.
Separately, the sur~actant emulsion of the phosphate
anti-foaming agent (LPKN), stearic acid or fatty acid mixture
and detergent (Dowfax 3B2) is prepared by adding these
ingredients to the remaining 3~ of water and heating the
20 resulting mi~ture to a temperature in the range of 160F
(71C). In formulation E, the Acrysol LMW 45-N may be added at
this stage.
The rheograms for the formulations A, B, C, D, E and F
are shown in figures 1-6, respectively.
These rheograms are obtained with the System ~ Rheometer
from Rheometrics equipped with a Fluid Servo with a 100 grams-
centimeter torgue transducer and a 50 millimeter parallel
plate geometry having an 0.8 millimeter gap between plates.
42
J ~ i
All measurements are made at room temperature (25~1C) in a
humidity chamber after a 5 minute or 10 minute holding period
of the sample in the gap. The measurements are made by
applying a frequency of 10 radians per second.
All of the composition formulations C, D and F e~chibit
linear viscoelasticity as seen from the rheograms of figure 2-
6. No phase separation at from ambient temperature to 140F
were observed for any of the formulations for at least the
minimum number of weeks required to satisfy the criteria
stability as shown in Table A above. Formulations Æ and F
were still being tested when this application was filed.
However, in the control formulations A and B maintained
at 100F, the TKPP crystallized in the a~ueous phase and
eventually formed sufficiently large size crystals which
separated to the bottom of the composition. Also, as seen in
figures 1 and 2 formulations A and B are not linear
viscoelastic, at least within the preferred criteria as
previously described. Formulations C, D, E and F, according
to the invention did not undergo any crystal growth.
For the bottle residue test, each formulation i9 allowed
to age for about 1 week at ambient temperatuxe in a standard
32 ounce small necked polyethylene bottle. An amount of
product is poured from the bottle to fill a standard sized
dispenser cup of an automatic dishwasher. The bottle is ~hen
replaced in an upright position and i9 retained in the upright
position for at least 15 minutes. This procedure of filling
the dispenser cup, placing the container in the upright
position and waiting at least 15 minutes is repeated until no
1' 3, ~
more product flows from the bottle. At this time, the weight
of the bottle is measured. Bottle residue ls calculated as
W~ x 100
Wo
Wo is the initial weight of the filled bottle and Wf is the
final weight of the filled bottle. The bottle residue for
each formulation A-F is about 4 to 5~. Formulations C-F have
viscosities of from 10,000 to 20,000 measured with a
Brookfield LVT viscometer, #4 spindle at 20 rpm measured at
80F. All of these products are easily pourable from the
polyethylene bottle.
xample 2
A Carbopol 614 slurry is formed as described in ~xample 1
except that the coloring agent i9 first added to the deionized
water (about 92% of the total added water) and the amounts of
the ingredients are changed as shown below. The premix
(surfactant emulsion) of the surface active ingredients is
also formed as in Example 1 using stearic acid as the fatty
acid stabilizer and the remaining 8~ of the total added water.
The ingredients are then mixed together with the Carbopol
614 slurry in the following order: alkali metal silicate,
NaTPP (powder), KTPP (powder), surfactant emulsion, bleach and
perfume. The re~ulting composition i9 obtained with the
following ingredients in the following amounts:
Inqredient Amount (wt. %)
Deionized water q.s. 100.00
Carbopol 614 1.00
NaOH (38% Na2O) 6.38
Na silicate (1:24)(47.5%) 20.83
KTPP (anhydrous) powder 20.35
44
NaTPP (3% H2O) 5.26
Dowfax 3B2 0.80
LPKN 0.16
Stearic acid 0.15
Bleach (Na hypochlorite-13~) 9.23
CI Pigment Green 7 (CI 74260) 0.0024
Highlights (fragrance) 0.05
The composition has a pH of 11.3 + 0.1 and dens~ty (sp.
gr.) of 1.39 + 0.03. The viscosity at 80F measured with a
Brookfield LVT ~iscometer at 20 rpm with a #4 spindle is
12,000 + 2,000.
All of the preferred criteria as set forth in Table A
above are satisfied.
Example 3
The following formulas were prepared according to the
procedure of Example 1 and tested.
Table II
Ingredient Amount (wt. ~)
Color Graphtol Green .003
Water Distilled 40.947
Carbopol 614 1.0
Na silicate (47.5%) 20.83
NaOH 4.50
NaTPP 2.00
LPKN - 158 0.10
Stearic Acid 0.08
Isostearic Acid 0.03
Fragrance 0.03
Bleach (13~) 10.13
Stability 3 months Stable No Sedimination
Brookfield Viscosity
At R.T. Spendle #64
1. # rpms 15,600 cps
2. 30 rpms 3,340 cps
Thixotropic Index 4.19
