Note: Descriptions are shown in the official language in which they were submitted.
2091 ~1 8 IR-4681A-l
L ~ ~ VT~m~
LIQUID AUTOMP~Tr nTe~ ~vD
n~ N~-rQr~ oN~-
Field of Invention
The present invention relates generally to an automatiedishwasher detergent composition in the form of an aqueous
lineAr viseoelastic liquid.
Baekqround of the Invention
Liquid automatie dishwasher detergent c~ -itions, both
aqueous and nonaqueous, have reeently reeeived mueh attention,
and the aqueous products have achieved commereial popularity.
The aeeeptanee and popularity of the liquid formulations
as compared to the more conventional powder produets stems
from the convenienee and performanee of the liquid produets.
However, even the best of the currently available liquid
formulations still suffer from two major problems, produet
phase instability and bottle residue, and to some extent cup
leakage from the dispenser cup of the automatie dishwashing
~eh;~e.
Representative of the relevant patent art in this area,
mention is made of Rek, U.S. Patent 4,556,504; Bush, et al.,
U.S. Patent 4,226,736; Ulrich, U.S. Patent 4,431,5S9;
- -- 2091418
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 detergent compositions include U.S.
Patent 3,985,668; U.K. Patent Applications GB 2,116,199A and
GB 240,450A; U.S. Patent 4,511,487; U.S. Patent 4,752,409
(Drapier, et al.); U.S. Patent 4,801,395 (Drapier, et al.);
U.S. Patent 4,801,395 (Drapier, et al.). Cnm~ly assigned
co-pending patents include, for example, Serial No. 204,476
filed June 9, 1988; Serial No. 924,385, filed October 29,
1986; Serial No. 323,138, filed March 13, 1989; Serial No.
087,836, filed August 21, 1987; 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 present invention provides a solution to the above
problems.
Brief Description of the Drawings
Figures 1-13 are rheograms, plotting elastic modules G'
and viscous modulus G" as a function of applied strain, for
the compositions of Example 1, Formulations A, C, D, G, J, H,
I and K, Example 2, A and B, Example 3, L and M and
Comparative Example 1, respectively.
2 ~ 9 1 4 1 8 62301-1821
.
Summary of the Invention
According to the present invention there is provided
a novel aqueous liquid automatic dishwasher detergent composi-
tion. The composition is characterized by its linear visco-
elastic behavior, substantially indefinite stability against
phase separation or settling of dissolved or suspended
particles, low levels of bottle residue, relatively high bulk
density, and substantial absence of unbound or free water. The
composition does not exhibit phase separation and remains
homogeneous when it is centrifused at 1,000 rpm for 30 minutes.
This unique combination of properties is achieved by virtue of
the incorporation into the aqueous mixture of alkali metal
detergent builder salt(s) and chlorine bleach compound, a small
but effective amount of high molecular weight cross-linked
polyacrylic acid type thickening agent, and a source of
potassium ions to provide a potassium/sodium weight ratio in
the range of from about 1:1 to about 1:30, such that
substantially all of the detergent builder salts and other
normally solid detergent additives present in the composition
are present dissolved in the aqueous phase. The compositions
are further characterized by a bulk density of from about 1.26
g/cm to about 1.42 g/cm3 such that the density of the polymeric
phase and the density of the aqueous (continuous) phase are
approximately the same.
Detailed Description of the Preferred Embodiments
The compositions of this invention are aqueous
liquids containing various cleansing active ingredients,
thickening agents and stabilizing
- 2091418-
components, although some ingredients may serve more than one
of these functions.
The advantageous characteristics of the compositions of
this invention, including physical stability, low bottle
residue, high cleaning performance, e.g. low spotting and
filming, dirt residue removal, and so on, and superior
aesthetics, are believed to be attributed to several
interrelated factors such as low solids, i.e. llnAiscolved
particulate content, product density and linear viscoelastic
rheology. These factors are, in turn, dependent on several
critical compositional components of the formulations, namely,
(1) the inclusion of a thickening effective amount of
polymeric thickening agent having high water absorption
capacity, exemplified by high molecular weight cross-linked
polyacrylic acid, (2) inclusion of a physical stabilizing
amount of a long chain fatty acid or salt thereof, (3)
potassium ion to sodium ion weight ratio K/Na in the range of
from about 1:1 to 1:30, especially from 1.05:1 to 1:10, and
(4) a product bulk density of at least about 1.26 glcc, such
that the bulk density and liquid phase density are about the
same.
The polymeric thickening agents contribute to the linear
viscoelastic rheology of the invention compositions. As used
herein, "linear viscoelastic "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 0-80%. More
- 2091~18
specifically, a composition 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 min;mllm
value of 100 dynes/sq.cm., preferably at least 250
dynes/sq.cm., and varies less than about 500 dynes/sq.cm,
preferably less than 300 dyneslsq.cm., especially preferably
less than 100 dynes/sq.cm. Preferably, the m; n; mllm 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
(tanS) is less than 1, preferably less than 0.8, but more than
O.OS, preferably more than 0.2, at 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' is a measure of the energy stored and retrieved
when a strain is applied to the composition while viscous
(loss) modulus G" is a measure to the amount of energy
dissipated as heat when strain is applied. Therefore, a value
of tan~
0.05< tan ~ <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
2~91418
- 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 subject linear viscoelastic compositions,
the compositions will readily flow uniformly and homogeneously
from a bottle when the bottle is tilted, thereby contributing
to the physical (phase) stability of the formulation and the
low bottle residue (low product loss in the bottle) which
characterizes the invention compositions. 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
surrounding fluid medium.
Also contributing to the physical stability and low
bottle residue of the invention compositions is the potassium
to sodium ion ratios in the range of 1:1 to 1:30, preferably
1:1 to 20:1, especially preferably from 1.05:1 to 1:10.
A still further attribute of the invention compositions
contributing 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
- ~ 2031418
aqueous vehicle component is held tightly bound to the polymer
matrix. Therefore, there is no or substantially no free water
present in the invention compositions. This absence of free
water (as well as the cohesiveness of the composition) is
manifested by the observation that when the composition is
poured from a bottle onto a piece of water absorbent filter
paper virtually no water is absorbed onto the filter paper
and, furthermore, the mass of the linear viscoelastic material
poured onto the filter paper will retain its shape and
structure until it is again subjected to a stress or strain.
As a result of the absence of unbound or free 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
lS compositions are subjected to centrifugation, e.g. at 1000 rpm
for 30 minutes, there is no phase separation and the
composition r~mA; ns homogeneous.
However, it has also been discovered that linear
viscoelasticity and K/Na ratios in the above-mentioned range
do not, by themselves, assure long term physical stability (as
determined by phase separation). In order to m~xi~ize
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 thicke~ing agent.
This control and equalization of the densities is achieved,
according to the invention, by providing the composition with
a bulk density of at least 1.26 g/cc, preferably at least 1.32
-- ~. 2091~18
g/cc, up to about 1.42 g/cc, preferably up to about 1.40 g/cc.
Furthermore, to achieve these relatively high bulk densities,
it is important to mi n;m; ze the amount of air incorporated
into the composition (a density of about 1.42 g/cc is
essentially equivalent to zero air content).
It has previously been found in connection with other
types of thickened aqueous liquid, automatic dishwasher
detergent compositions that incorporation of finely divided
air bubbles in amounts up to about 8 to 10% by volume can
function effectively to stabilize the composition against
phase separation, but that to prevent agglomeration of or
escape of the air bubbles it was important to incorporate
certain surface active ingredients, especially higher fatty
acids and the salts thereof, such as stearic acid, hehen;c
acid, palmitic acid, sodium stearate, aluminum stearate, and
the like. These surface active agents apparently functioned
by forming an interfacial film at the bubble surface while
also forming hydrogen bonds or contributing to the
electrostatic attraction with the suspended particles, such
that the air bubbles and attracted particles formed
agglomerates of approximately the same density as the density
of the continuous liquid phase.
Therefore, in a preferred emboA;m~nt of the present
invention, stabilization of air bubbles which may become
2~ incorporated into the compositions during normal processing,
such as during various mixing steps, is avoided by post-adding
the surface active ingredients, including fatty acid or fatty
acid salt stabilizer, to the rem~;nAer of the composition,
- - - - -
r-~ 2 091 ~ 1 8
under low shear conditions using mix;ng devices designed to
m;ni~ize cavitation and vortex formation.
As will be described in greater detail below the surface
active ingredients present in the composition will include the
main detergent surface active cleaning agent, and will also
preferably include anti-foaming agent and higher fatty acid or
salt thereof as a physical stabilizer.
Exemplary of the cross-linked polyacrylic acid-type
thickening agents are the products sold by B.F. Goodrich under
their Carbopol trA~em~rk, especially Carbopol 941, which is
the most ion-insensitive of this class of polymers, and
Carbopol 940 and Carbopol 934. The Carbopol resins, also
known as "Carbomer", are hydrophilic high molecular weight,
cross-linked acrylic acid polymers having an average
equivalent weight of 76, and the general structure illustrated
by the following formula:
H H
C- C
l l
H C n.
HO O
Carbopol 941 has a molecular weight of about 1,250,000;
Carbopol 940 a molecular weight of approximately 4,000,000 and
Carbopol 934 a molecular weight of approximately 3,000,000.
The Carbopol resins are cross-linked with polyalkenyl
polyether, e.g. about 1% of a polyallyl ether of sucrose
having an average of about 5.8 allyl groups for each molecule
of sucrose. Further detailed information on the Carbopol
--
- -
r-~ 2 0 9 1 1 1 8
resins is available from B.F. Goodrich, see, f or example, the
B.F. Goodrich catalog GC-67, Carbopol~ Water Soluble Resins.
While most f avorable results have been achieved with
Carbopol 941 polyacrylic resin, other lightly cross-linked
polyacrylic acid-type thickening agents can also be used in
the compositions of this invention. As used herein
"polyacrylic acid-type" refers to water-soluble homopolymers
of acrylic acid or methacrylic acid or water-dispersible or
water-soluble salts, esters or amides thereof, or water-
soluble copolymers of these acids of their salts, esters or
ameides with each other or with one or more other etylenically
unsaturated monomers, such as, for example, styrene, maleic
acid, maleic anhydride, 2-hydroxyethylacrylate, acrylonitrile,
vinyl acetate, ethylene, propylene, and the like.
The homopolymers or copolymers are characterized by their
high molecular weight, in the range of from about 500,000 to
10,000,000, preferably 500,000 to 5,000,000, especially from
about 1,000,000 to 4,000,000, and by their water solubility,
generally at least to an extent of up to about 5% by weight,
or more, in water at 25~C.
These thickening agents are used in their lightly 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-
r~ 2 0 9 1 4 1 8
bisacrylamide, polyalkenylpolyethers (such as described
above~, and the like. Typically, amounts of cross-li nki ng
agent to be incorporated in the final polymer may range from
about 0.01 to about l.S percent, preferably from about 0.05 to
about 1.2 percent, and especially, preferably from about 0.1
to about 0.9 percent, by weight of cross-linking 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 polymeric compound while maint~;n;ng the cross-linked
polymer at least water dispersible and highly water-swellable
in an ionic aqueous medium. It is also understood that the
water-swelling of the polymer which provides the desired
thickening and viscous properties generally depends on one or
two mechanisms, namely, conversion of the acid group
cont~;n;ng polymers to the corresponding salts, e.g. sodium,
generating negative charges along the polymer backbone,
thereby causing the coiled molecules to expand and thicken the
aqueous solution; or by formation of hydrogen bonds, for
example, between the carboxyl groups of the polymer and
hydroxyl donor. The former mechanism is especially important
in the present invention, and therefore, the preferred
polyacrylic acid-type thickening agents will contain free
carboxylic acid (COOH) groups along the polymer backbone.
-25 Also, it will be understood that the degree of cross-l;nk;ng
should not be so high as to render the cross-linked polymer
completely insoluble or non-dispersible in water or inhibit or
~ 2091 418
prevent the uncoiling of the polymer molecules in the presence
of the ionic aqueous system.
The amount of at least one high molecular weight, cross-
linked polyacrylic acid or other high molecular weight,
hydrophilic cross-linked polyacrylic acid-type thickening
agent to impart the desired rheological property of l; neAr
viscoelasticity will generally be in the range of from about
0.1 to 2%, preferably from about 0.2 to 1.75%, by weight,
based on the weight of the composition, although the amount
will depend on 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 1:1 to 1:30. When the K/Na ratio is
less than 1 there is less solubility of the normally solid
ingredients making a less transcluent composition with
acceptable cleaning performance whereas when the K/Na ratio is
more 1:1 the composition is a more translucent composition.
When the K/Na ratio is more than 45, especially when it is
greater than about 3, the product becomes too liquid and phase
separation begins to occur. When the K/Na ratios become much
larger than 45, such as in all or mostly potassium
formulation, the polymer thickener loses its absorption
capacity and begins to salt out of the aqueous phase.
The potassium and sodium ions can be made present in the
compositions as the alkali metal cation of the detergent
builder salt(s), or alkali metal silicate or alkali metal
hydroxide components of the compositions. The alkali metal
20~1 ~18
cation may also be present in the compositions as a component
of an ionic 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 include 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. The phosphate
builders, where not precluded due to local regulations, are
preferred and mixtures of tetrapotassium pyrophosphate (TKPP)
and sodium tripolyphosphate (NaTPP) (especially the
hexahydrate) are especially preferred. Typical ratios of
NaTPP to TKPP are from about 2:1 to 1:8, especially from about
1:1.1 to 1:6. The total amount of detergent builder salts is
preferably from about S to 35% by weight, more preferably from
about 15 to 35%, especially from about 18 to 30% by weight of
the composition.
In connection with the builder salts are optionally used
a low molecular weight noncrosslinked polyacrylates having a
molecular weight of about 1,000 to about 100,000, more
preferably about 2,000 to about 80,000. A preferred low
molecular weight polyacrylate is Norasol LMW45ND manufactured
- 2~91~18
by Norsoshaas and having a molecular weight of about 4,500.
These low molecular weight polyacrylates are employed at a
concentration of about O to 15 wt.%, more preferably 0.1 to 10
wt.%.
Other useful low molecular weight noncrosslinked polymers
are Acusoltm6 4OD provided by Rohm & Haas; Norasol QR1014 from
Norsohaas having a GPC molecular weight of 10,000.
The linear viscoelastic compositions of this invention
may, and preferably will, contain a small, but stabilizing
effective amount of a long chain fatty acid or monovalent or
polyvalent salt thereof. 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 function as a hydrogen bonding agent
or cross-linking agent for the polymeric thickener.
The preferred long chain fatty acids are the higher
aliphatic fatty acids having from about 8 to 22 carbon atoms,
more preferably from about 10 to 20 carbon atoms, and
especially preferably from about 12 to 18 carbon atoms, and
especially preferably from about 12 to 18 carbon atoms,
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 acid, soya fatty acid,
mixtures of these acids, etc. Stearic acid and mixed fatty
acids, e.g. stearic acid/palmitic acid, are preferred.
14
2U91418
~ 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. However, 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 the di- and tri-
valent metals of Groups IIA, IIB and IIIB, such as magnesium,
calcium, aluminum and zinc, although other polyvalent metals,
including those of Groups IIIA, IVA, VA, IB, IVB, VB, VIB 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
pentavalent state. Preferably the metal salts are used in
their higher oxidation states. Naturally, for use in
automatic dishwashers, as well as any other applications where
the invention composition will or may come in contact with
articles used for the h~n~l;ng, storage or serving of food
products or which otherwise may come into contact with or be
consumed by people or ~nim~lfi, the metal salt should be
selected by taking into consideration the toxicity of the
-25 metal. For this purpose, the alkali metal and calcium and
magnesium salts are especially higher preferred as generally
safe food additives.
2091~18 --
The amount of the fatty acid or fatty acid salt
stabilizer to achieve the desired enhancement of 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
acid salt stabilizing agents in the range of from about 0 to
2.0%, preferably 0.005 to 2.0%, more preferably from about
0.01 to 2.0%, provide a long term stability and absence of
phase separation upon stAn~;ng or during transport at both low
and elevated temperatures as are required for a commercially
acceptable product.
Depending on the amounts, proportions and types of fatty
acid physical stabilizers and polyacrylic acid-type thickening
agents, the addition of the fatty acid or salt not only
increases physical stability but also provides a simultaneous
increase in apparent viscosity. Amounts of fatty acid or salt
to polymeric thickening agent in the range of from about
0.005-0.4 weight percent fatty acid salt and from about 0.4-
1.75 weight percent polymeric thicken;ng agent are usually
sufficient to provide these simultaneous benefits and,
therefore, the use of these ingredients in these amounts is
most preferred.
In order to achieve the desired benefit from the fatty
acid or fatty acid salt stabilizer, without stabilization of
excess incorporated air bubbles and consequent excessive
16
2~1418
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 fatty materials are
finely and homogeneously dispersed throughout 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~C-69~C, a
temperature in the range of between 50~C and 70~C will be
used. For lauric acid (m.p.=47~C) an elevated temperature of
about 35~C to 50~C can be used. Apparently, at these elevated
temperatures the fatty acid or salt and other surface active
ingredients can be more readily and uniformly dispersed
(emulsified) in the form of fine droplets throughout the
composition.
In contrast, as will be shown in the examples which
follow, if the fatty acid is simply post-added at ambient
temperature, the composition is not linear viscoelastic as
defined above and the stability of the composition is clearly
inferior.
Foam inhibition is important to increase dishwasher
machine efficiency and m;~;m; ze destabilizing effects which
might occur due to the presence of excess foam within the
;. 2091gl8
washer during use. Foam may be reduce 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
bleach stable foam depressant or inhibitor. Particularly
effective are the alkyl phosphoric acid esters of the formula
HO-P-R
ll
OR
and especially the alkyl acid phosphate esters of the formula
~
HO-P-OR
OR
In the above formulas, one or both R groups in each type of
ester may represent independently a Clz-C20 alkyl or
ethoxylated 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-
2~91~18
esters of the same type, may be employed. Especially
preferred is a mixture of mono- and di-C1~-C18 alkyl acid
phosphate esters such as monostearyl/distearyl acid phosphates
1.2/1, and the 3 to 4 molé 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 about 5:1 to 1:1. Other
defoamers which may be used include, for example, the known
silicones, such as available from Dow Chemicals. In addition,
it is an advantageous feature of 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 dichloro-
isocyanurate, 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 contain sufficient amount of chlorine
bleach compound to provide about 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 cont~;n;ng about 0.2 to 4.0% by
weight of sodium hypochlorite contains or provides roughly the
same percentage of available chlorine. About 0.8 to 1.6% by
weight of available chlorine is especially preferred. For
19
- -
- 2091418
~xample, sodium hypochlorite (NaOCL) solution of from about 11
to about 13% available chlorine in amounts of about 3 to 20%,
preferably about 7 to 12%, can be advantageously used.
Detergent active material useful herein should be stable
in the presence of chlorine bleach, especially hypochlorite
bleach, and for this purpose those of the organic anionic,
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-C14) 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 C1O_C18
alkylsulphates such as sodium dodecylsulphate and sodium
tallow alcoholsulphate; sodium Clo-cl8 alkanesulphonates such
as sodium hexadecyl-1-sulphonate and sodium C12-Cl8
alkylbenzenesulphonates such as sodium
dodecylbenzenesylphonates. The corresponding potassium salts
may also be employed.
~5 As other suitable surfactants or detergents, the amine
oxide surfactants are typically of the structure R2R1NO, in
which each R represents a lower alkyl group, for instance,
methyl, and R1 represents a long chain alkyl group having from
2091418
~ to 22 carbon atoms, for instance a lauryl, myristyl,
palmityl or cetyl group. Instead of an amine oxide, a
corresponding surfactant phosphine oxide R2R1PO or sulphoxide
RRlSO can be employed. Betaine surfactants are typically of
the structure R2R1N+R"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, myristyl-dimethylamine
oxide, the corresponding phosphine oxides and sulphoxides, and
the corresponding betaines, including dodecyldimethylammonium
acetate, tetradecyldiethylammonium pentanoate,
hexadecyldimethylammonium hexanoate and the like. For
biodegradability, 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 is not used than any of the
well known low-foaming nonionic surfactants such as
alkoxylated fatty alcohols, e.g. mixed ethylene oxide-
propylene oxide condensates of C8-Cz2 fatty alcohols can also
be used.
The chlorine bleach stable, water dispersible organic
detergent-active material (surfactant) will normally be
present in the composition in minor amounts, generally about
1% by weight of the composition in minor amounts, generally
about 1% by weight of the composition, although smaller or
larger amounts, such as up to about 5%, such as from 0.1 to
- ~---- 2091418
j%, preferably form 0.3 or 0.4 to 2% 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 about 0 to 25 weight percent, preferably
about 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 aqueous solution, preferably having
Na2O:SiOz or KzO:SiO2 ratio of about 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 preli mi n~ry prepared aqueous
dispersion or solution.
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 alk~li ni ty, and particularly to moderate to high
alkalinity levels. Accordingly, the compositions of this
invention will have pH values of at least about 9.5,
preferably at least about 11 to as high as 14, generally up to
about 13 or more, and, when added to the aqueous wash bath at
a typical concentration level of about 10 grams per liter,
will provide a pH in the wash bath of at least about 9,
--- 2091418
preferably at least about 10, such as 10.5, 11, 11.5 or 12 or
more.
The alkalinity will be achieved, in part by the alkali
metal ions contributed by the alkali metal detergent builder
salts, e.g. sodium tripolyphosphate, tetrapotassium
pyrophosphate, and alkali metal silicate, however, it is
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 (on an active basis) of
from about 0.5 to 8%, preferably from 1 to 6%, more preferably
from about 1.2 to 4%, by weight of the composition will be
sufficient to achieve the desired pH level and/or to adjust
the K/Na weight ratio.
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
composltion .
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
alk~l; n; ty. Especially preferred for coloring are the
chlorinated phythalocyanines and polysuphides of
aluminosilicate which provide, respectively, pleasing green
and blue tints. TiO2 may be employed for whitening or
neutralizing off-shades.
2~91418
,
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 about 10% by
volume, preferably up to about 4% by volume, more preferably
up to about 2% by volume, can be incorporated to adjust the
bulk density to approximate liquid phase density. The
incorporated air bubbles should be finely divided, such as up
to about 100 microns in diameter, preferably from about 20 to
about 40 microns in diameter, to assure maximum stability.
Although air is the preferred gaseous medium for adjusting
densities to improve physical stability of the composition
other inert gases can also be used, such as nitrogen, carbon
dioxide, 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 properties
in either case being ~imi ni shed or destroyed by increasing tan
1. Such amount is readily determined by routine
experimentation in any particular instance, generally ranging
from 30 to 75 weight percent, preferably about 35 to 65 weight
percent. The water should also be preferably 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
--- 2091418
,
performed will generally have a significant effect on the
properties of the composition, and in particular on product
density (by incorporation and stabilization of more or less
air) and physical stability (e.g. phase separation). Thus,
according to the preferred practice of this invention the
compositions are prepared by first forming a dispersion of the
polyacrylic acid-type thickener in water under moderate to
high shear conditions, neutralizing the dissolved polymer to
cause gelation, and then introducing, while continl~;ng mixing,
the detergent builder salts, alkali metal silicates, chlorine
bleach compound and rem~i~;ng detergent additives, including
any previously unused alkali metal hydroxide, if any, other
than the surface-active compounds. All of the additional
ingredients can be added simultaneously or sequentially.
Preferably, the ingredients are added sequentially, 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 mixing steps should also be
performed under moderate to high shear rates to achieve
complete and uniform mixing. These mixing steps may be
carried out at room temperature, although the polymer
thickener neutralization (gelation) is usually exothermic.
The composition may be allowed to age, if necessary, to cause
~5 dissolved or dispersed air to dissipate out of the
composition.
The rem~ining surface active ingredients, including the
anti-foaming agent, organic detergent compound, and fatty acid
- 2091~18
~r fatty acid salt stabilizer is post-added to the previously
formed mixture in the form of an aqueous emulsion (using from
about 1 to 10%, preferably from about 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 about Tm+5 to
Tm-20, preferably from about Tm to TM-10, where Tm is the
melting point temperature of the fatty acid or fatty acid
salt. For the preferred stearic acid stabilizer the heating
temperature is in the range of 50~C to 70~C. However, if care
is taken to avoid excessive air bubble incorporation during
the gelatin step or during the mixing of the detergent builder
salts and other additives, for example, by operating under
vacuum, or using low shearing conditions, or special mixing
operatatus, 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 includes, on a weight
basis:
(a) 10 to 35%, preferably 15 to 30%, alkali metal
detergent builder salt;
(b) 0 to 25, preferably 15 to 15%, alkali metal
silicate;
(c) 0 to 6%, preferably 1 to 6%, 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;
26
2091~18
(e) 0 to 1.5%, preferably 0.1 to 1.5%, chlorine bleach
.stable foam depressant;
(f) chlorine bleach compound in an amount to provide
about 0.2 to 4%, preferably 0.8 to 1.6%, of available
chlorine;
(g) at least one high molecular weight hydrophilic
cross-linked polyacrylic acid thickening agent in an amount to
provide a linear viscoelasticity to the formulation,
preferably from about 0.1 to 2.0%, more preferably from about
0.2 to 1.75%;
(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 to
2.0%, more preferably from 0.005 to 2.0%; and
(i) balance water, preferably from about 30 to 75%, more
preferably from about 35 to 65%; and wherein in (a) the alkali
metal polyphosphate includes a mixture of from about 5 to 30%,
preferably from about 12 to 22% of tetrapotassium
pyrophosphate, and from 0 to about 20%, preferably from about
3 to 18% of sodium tripolyphosphate, and wherein in the entire
composition the ratio, by weight, of potassium ions to sodium
ions is from about 1:1 to 1:30 preferably from 1:1 to 1:20,
the compositions having an amount of air incorporated therein
such that the bulk density of the composition is from about
1.26 to 1.42 g/cc, preferably from about 1.32 to 1.40 g/cc.
The compositions will be supplied to the consumer in
suitable dispenser containers preferably formed of molded
plastic, especially polyolefin plastic, and most preferably
27
- - 2091418
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 may 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, although
squeezable containers are often convenient and accepted by the
consumer for gel-like products.
The liquid aqueous linear viscoelastic automatic
dishwasher compositions of this invention are readily employed
in known 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 cont~in;ng 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
wash bath cont~; n; ng an effective amount of the liquid linear
viscoelastic automatic dishwasher detergent composition as
described above. The composition can be readily poured from
the polyethylene cont~;ner with little or no squeezing or
shaking into the dispensing cup of the automatic dishwashing
machine and will be sufficiently viscous and cohesive to
remain securely within the dispensing cup until shear forces
28
- 20~1~18
are again applied thereto, such as by the water spray from the
dishwashing machine.
The invention may be put into practice in various ways
and a number of specific emhodimpnts will be described to
illustrate the invention with reference to the accompanying
examples. I
All the amounts and proportions referred to herein are by
weight of the composition unless otherwise indicated.
Example 1
The following formulations A-K were prepared as described below:
INr~nTR~T ¦ A B C D E F G H I J K
/FORMULATION
DEIONIZED WATER BAL. BAL. BAL. BAL. BAL. BAL. BAL. BAL. BAL. BAL. BAL.
CARBOPOL 941 0.9 0.9 0.9 0.9 1 --- 0.9 0.9 --- 1.5 0.9
NaOH (50%) 2.4 2.4 2.4 2.4 3.5 3.5 2.4 --- 2.4 2.4 2.4
KOH (50%) --- --- --- --- --- --- --- 2.4 --- --- ---
TKPP 15 15 15 20 20 20 28 28 15 20 15
TPP 13 13 12 7.5 7.5 7.5 --- --- 13 7.5 13
HEXAHYDRATE, Na
Na SILICATE 21 21 21 21 17 17 21 --- 21 21 21(47.5%)(1:2.3)
K SILICATE --- --- --- --- --- --- --- 34 --- --- --- G
(29.1%)(1:2.3) ~p
LPKN (5%) 3.2 3.2 3.2 3.2 --- --- 3.2 3.2 3.2 3.2 3.2
DOWFAX 3B2
FATTY ACID2 0.1 0.1 0.1 0.1 --- --- 0.1 0.1 1 0.1 0.1
BLEACH (13.0% 7.5 7.5 7.5 7.5 9.1 9.1 7.5 7.5 7.5 7.5 9
CL)
AIR3 Vol.~) <2.0 <2.0 <2.0 <2.0 <2.0 >2.0 <2.0 ~2.0 >2.0 <2.0 <2.0
FRAGRANCE --- 0.17 --- --- --- --- --- --- --- --- ---
K/Na RATIO 1.12 1.12 1.16 1.89 1.95 1.95 4.16 45.15 --- 1.89 ---
lo q / 't l ~
0
--
a~ ,~
In C E ~d
r ~ O ~
o o
, ,,~ . . ~ OS
~ :4 o o
_ c~
O R ~~
o O 0
H 1 14 ~ ~ r
--- _
a; ~
~D O O a
. . . S
I~ o o ~;
I.,~ ~ ~ ~L
~ I ~ ~
0
_ ~ o _
V ,~ ~4 o ~ o~
~ 1 s~
o o ~ 1 C
~ ~ ~ 1 td-~l
I o o
I
I ~ ~ ~- ~ o
~1 1)
_
o o ~~ a~
~ o o ~ o
_
.c a~
~ ~~ o
r ~ E a~
~~ o o ~1
. ~,1 ~ ~ ~ , o
a ~ ~4 0 0
_
~ ~ ~.C' R~
u~ . ~ L o
O O ~ P ~D
~ ~:4 0 ~ '
_
c O
1 o
o o uo_ ~~
' ' ' a~ r
1~~ o o 4
o ~
1~ U 1) 3
r
o o ~ C ~0
_, ~4 0 0 ., ~a s 1)
O ~ Ll ~ _
_~ rr er ~ S~ O
O f a~ ~\ 0 41 >
O L ~ ~ 4/
tr ~ . ~ ~ ,,u,
Z ~ ~ ~no3 ~ u~o--
~0 ~ ~oO~o
~ ~ u~ co u ~ ~--
_
2091~18
Formulations A, B, C, D, E, G, J, and K are prepared by
~first forming a uniform dispersion of the Carbopol 941 or 940
thickener in about 97% of the water (balance). The Carbopol
is slowly added to deionized water at room temperature using a
mixer equipped with a premier blade, with agitation set at a
medium shear rate, as reco~ en~ed by the manufacturer. The
dispersion is then neutralized by addition, under mixing, of
the caustic soda (50% NaOH or KOH) component to form a
thickened product of gel-like consistency.
To the resulting gelled dispersion the silicate,
tetrapotassium pyrophosphate (TKPP), sodium tripolyphosphate
TP(TPP, Na) and bleach, are added sequentially, in the order
stated, with the mixing continued at medium shear.
Separately, an emulsion of the phosphate anti-foaming
agent (LPKN), stearic acidlpalmitic acid mixture and detergent
(Dowfax 3B2) is prepared by adding these ingredients to the
re~;n;ng 3% of water (balance) and heating the resulting
mixture to a temperature in the range of 50~C to 70~C.
This heated emulsion is then added to the previously
prepared gelled dispersion under low shear conditions, such
that a vortex is not formed.
The rem~;n;ng formulations F, H and I are prepared in
essentially the same manner as described above except that the
heated emulsion of LPKN, stearic acid and Dowfax 3B2 is
directly added to the neutralized Carbopol dispersion prior to
the addition of the r~m~;n;ng ingredients. As a result,
formulations F, H and I, have higher levels of incorporated
air and densities below 1.30 g/cc.
- - - -- - ~ -
. _ 2 o~
The rheograms for the formulations A, C, D, G and J are
shown in figures 1-5, respectively, and rheograms for
formulations H, I and K are shown in figures 6, 7 and 8
respectively.
These rheograms are obtained with the System 4 Rheometer
from Rheometrics equipped with a Fluid Servo with a 100 grams-
centimeter torque transducer and a 50 millimeter parallel
plate geometry having an 0.8 millimeter gap between plates.
All measurements are made at room temperature (25~C+1~C) 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 A, B, C, D, G and J
according to the preferred embo~;m~t of the invention which
include Carbopol 941 and stearic acid exhibit linear
viscoelasticity as seen from the rheograms of figure 1-5.
Formulation E which includes Carbopol 941 but not stearic acid
showed no phase separation at either room temperature or 100~F
after 3 weeks, but exhibited 10% phase separation after 8
weeks at room temperature and after only 6 weeks at 100~F.
Formulation K, containing Carbopol 940 in place of
Carbopol 941, as seen from the rheogram in figure 8, exhibits
substantial linearity over the strain range of from 2% to 50%
(G' at 1% strain-G' at 50% strain 500 dynes/sq.cm.) although
tan 1 at a strain above 50%.
,.- 2~3l~l8
~xample 2
This example demonstrates the importance of the order of
addition of the surface active component premix to the
rP~;n~er of the composition on product density and stability.
The following formulations are prepared by methods A and
B:
Ingredient
Water, deionized Balance
Carbopol 941 0.5
NaOH (50%) 2.4
Na Silicate (47.5%) 21
TKPP 15
TPP, Na 13
Bleach (1%) 7.5
LPKN 0.16
Stearic Acid 0.1
Dowfax 3B2
Method A:
The Carbopol 941 is dispersed, under medium shear rate,
using a premier blade mixer, in deionized water at ambient
temperature. The NaOH is added, under mixing, to neutralize
and gel the Carbopol 941 dispersion. To the thickened mixture
the following ingredients are added sequentially while the
stirring is continued: sodium silicate, TKPP, TPP, and
bleach.
Separately, an emulsion is prepared by adding the Dowfax
3B2, stearic acid and LPgN to water while mixing at moderate
shear and heating the mixture to about 65~C to finely disperse
the emulsified surface active ingredients in the water phase.
This emulsion premix is then slowly added to the Carbopol
dispersion while mixing under low shear conditions without
forming a vortex. The results are shown below.
34
2091~1~
_
Method B:
Method A is repeated except that the heated emulsion
premix is added to the neutralized Carbopol 941 dispersion
before the sodium stearate, TKPP, TPP, and bleach. The
results are also shown below.
Method A Method B
Density (glcc) 1.38 1.30
Stability (RT-8 weeks)0.00% 7.00%
Rheogram Fig. 9 Fig.10
From the rheograms of figures 9 and 10 it is seen that
both products are linear viscoelastic although the elastic and
viscous moduli G' and G" are higher for Method A than for
Method B.
From the results it is seen that early addition of the
surface active ingredients to the Carbopol gel significantly
increases the degree of aeration and lowers the bulk density
of the final product. Since the bulk density is lower than
the density of the continuous liquid phase, the liquid phase
undergoes inverse separation (a clear liquid phase forms on
the bottom of the composition). This process of inverse
separation appears to be kinetically controlled and will occur
faster as the density of the product becomes lower.
Example 3
This example shows the importance of the temperature at
~ which the premixed surfactant emulsion is prepared.
Two formulations, L and M, having the same composition as
in Example 2 except that the amount of stearic acid was
increased from 0.1% to 0.2% are prepared as shown in Method A
2091~18
.
for formulation L and by the following Method C for
formulation M.
Method C
The procedure of Method A is repeated in all details
except that emulsion premix of the surface active ingredients
is prepared at room temperature and is not heated before being
post-added to the thickened Carbopol dispersion cont~i n; ng
silicate, builders and bleach. The rheograms for formulations
L and M are shown in figures 11 and 12, respectively. From
these rheograms it is seen that formulation L is linear
viscoelastic in both G' and G" whereas formulation M is non-
linear viscoelastic particularly for elastic modulus G' (G' at
1% strain-G' at 30% strain > 500 dynes/cm2) and also for G"
(G" at 1% strain-G" at 30% strain ~ 300 dynes/cmZ).
Formulation L re~; n.~ stable after storage at RT and
100~F for at least 6 weeks whereas formulation M undergoes
phase separation.
C~mrArative Example 1
The following formulation is prepared without any
potassium salts:
Weight %
Water Balance
Carbopol 941 0.2
NaOH (50%) 2.4
TPP, Na (50%) 21.0
Na Silicate (47.5%) 17.24
Bleach (1%) 7.13
Stearic Acid 0.1
LPKN (5%) 3.2
Dowfax 3B2 0.8
Soda Ash 5.0
Acrysol LMW 45-N 2.0
36
- 2(~91~18
.
The procedure used is analogous to Method A of Example 2
with the soda ash and Acrysol LMW 45-N (low molecular weight
polyacrylate polymer) being added before and after,
respectively, the silicate, TPP and bleach, to the thickened
Carbopol 941 dispersion, followed by addition to the heated
surface active emulsion premix. The rheogram is shown in
figure 13 and is non~ eAr with G"/G' (tan ) > 1 over the
range of strain of from about 5% to 80%.
Example 4
Formulations A, B, C, D and K according to this invention
and comparative formulations F and a commercial liquid
automatic dishwasher detergent product as shown in Table 1
above were subjected to a bottle residue test using a stAn~rd
polyethylene 28 ounce bottle as used for current commercial
liquid dishwasher detergent bottle.
Six bottles are filled with the respective samples and
the product is dispensed, with a min;mllm of force, in 80 gram
dosages, with a 2 minute rest period between dosages, until
flow stops. At this point, the bottle was vigorously shaken
to try to expel additional product.
The amount of product remAining in the bottle is measured
as a percentage of the total product originally filled in the
bottle. The results are shown below.
2091~18
~ Bottle Residue
Formulation Residue
A 8
B 10
C
D 5
K 7
F*
Co~rcial Product 20
~The sample separates upon aging.
