Liquid dishwashing detergent

Aqueous liquid dishwashing detergent compositions are prepared that exhibit improved detergency performance and foam stability over a range of water hardness levels. A preferred formulation incorporates a three component mixture: an anionic surfactant, a nonionic surfactant, and an amido amine oxide to provide a detergent having good detergency performance and foam stability over a range of water hardness levels. Another preferred formulation incorporates a three component mixture: an anionic surfactant, a nonionic surfactant, and an alkyl ethoxylated carboxylate to provide a detergent having good detergency performance and foam stability at high hardness levels.

BACKGROUND OF THE INVENTION 
This invention relates to light duty dishwashing detergents, and in 
particular, to light duty dishwashing detergents that are effective over a 
wide range of water hardness levels. Light duty liquid detergents, such as 
are suitable for use in the washing of dishes, are well known and have met 
with a high degree of consumer acceptance because of their good washing 
and foaming properties and convenient form for use. Most of the 
formulations in commercial use at the present time are based on synthetic 
organic detergents which, together with supplementing materials often 
used, give them satisfactory detergency and foaming properties. 
Nevertheless, there is an ongoing effort to make products that clean and 
foam even better and produce more stable foams. 
A particular problem with generally available detergents exists when the 
water used for washing is soft (i.e., has a hardness level less than 25 
ppm as CaCO.sub.3). At these low water hardness levels, the stability of 
the foam can be inadequate. Consequently, a need exists for a dishwashing 
detergent that provides good foam stability over a wide range of water 
hardness levels. 
Surprisingly, it has been found that a dishwashing detergent that is 
effective and provides stable foam over a wide range of water hardness 
levels can be prepared by combining, in a three component mixture, an 
amido amine oxide, an anionic surfactant, and a nonionic surfactant. The 
use of the amido amine oxide provides an unexpected increase in detergency 
and foam stability over a range of water hardness levels especially when 
compared to a detergent formulated with the same anionic and nonionic 
surfactant without the amido amine oxide. Surprisingly, a detergent 
containing the amido amine oxide shows a marked increase in performance as 
the water hardness level is increased when compared to detergents 
containing an alkyl amine oxide combined with an anionic and nonionic 
surfactant. 
Another problem with generally available detergents exists when the water 
used for washing has a hardness level greater than about 300 ppm (as 
CaCO.sub.3). At a high hardness level the amount of foam produced and the 
performance of the detergent is reduced. 
Unexpectedly, it has been found that a dishwashing detergent that is 
effective at high hardness levels can be prepared by combining, in a three 
component mixture, an alkyl ethoxylated carboxylate, an anionic 
surfactant, and a nonionic surfactant. A composition containing the alkyl 
ethoxylated carboxylate shows a surprising increase in detergency when 
used in hard water (greater than 300 ppm as CaCO.sub.3) as compared to the 
detergency of a composition without the alkyl ethoxylated carboxylate. 
The present invention thus provides a detergent that exhibits good 
detergency performance and foam stability over a range of water hardness 
levels and a detergent that exhibits good detergency and foam stability at 
high hardness levels. 
SUMMARY OF THE INVENTION 
According to one embodiment of the present invention, a detergent that 
provides good detergency and foam stability over a range of water hardness 
levels is provided, incorporating into a three component mixture: an 
anionic surfactant, a nonionic surfactant, and an amido amine oxide. 
According to a preferred embodiment, the detergent comprises, per 100 
parts by weight; 5 to 60 parts by weight of a mixture containing 2.5-95% 
anionic surfactant, 2.5-95% nonionic surfactant, and 2.5-95% amido amine 
oxide; 0 to 20 parts by weight of additives; and water comprising the 
balance. In a particular preferred embodiment, the anionic surfactant is a 
secondary alkane sulfonate and the nonionic surfactant is a fatty acid 
alkanolamide. 
According to another embodiment of the present invention, a detergent that 
provides good detergency and foam stability at high water hardness levels 
is provided, incorporating into a three component mixture: an anionic 
surfactant, a nonionic surfactant, and an alkyl ethoxylated carboxylate. 
According to a preferred embodiment, the detergent comprises, per 100 
parts by weight; 5 to 60 parts by weight of a mixture containing 5-98% 
anionic surfactant, 1-94% nonionic surfactant, and 1-20% alkyl ethoxylated 
carboxylate; 0 to 20 parts by weight of additives; and water comprising 
the balance. In a particular preferred embodiment, the anionic surfactant 
is a secondary alkane sulfonate and the nonionic surfactant is a fatty 
acid alkanolamide. 
It is noted that, unless otherwise stated, all percentages given in this 
specification and the appended claims refer to percentages by weight. 
It is also noted that the hardness values, as used in this specification 
and the appended claims, is intended to refer to hardness expressed as 
calcium carbonate. 
These and other objects, advantages, and features of the present invention 
will be better understood upon review of the following detailed 
description of the preferred embodiments.

Referring to FIG. 1, the area for the combinations useful in carrying out 
the present invention according to the first embodiment have been labeled. 
Thus, the areas labeled, A, B, C, and D depict the useful, the preferred, 
the more preferred and the particularly preferred combinations for 
carrying out the invention according to the first embodiment, 
respectively. It will be apparent that they correspond with the ranges (in 
percent by weight): 
______________________________________ 
Component A B C D 
______________________________________ 
Anionic 2.5-95 20-90 40-85 50-80 
Surfactant 
Nonionic 2.5-95 5-75 5-55 10-40 
Surfactant 
Amido 2.5-95 2.5-60 5-40 5-30 
amine oxide 
______________________________________ 
Referring to FIG. 2, the area for the combinations useful in carrying out 
the present invention according to the second embodiment have been 
labeled. Thus, the areas labeled E, F, G, and H depict the useful, the 
preferred, the more preferred and the particularly preferred combinations 
for carrying out the invention according to the second embodiment, 
respectively. It will be apparent that they correspond with the ranges (in 
percent by weight): 
______________________________________ 
Component E F G H 
______________________________________ 
Anionic 5-98 25-93 50-88 60-85 
Surfactant 
Nonionic 1-94 5-60 10-40 15-37 
surfactant 
Alkyl 1-30 2-15 2-10 3-10 
ethoxylated 
carboxylate 
______________________________________ 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In a first embodiment of the invention, the detergent contains, by weight, 
5 to 60 parts of a three component mixture that incorporates an anionic 
surfactant, a nonionic surfactant, and an amido amine oxide; 0 to 20 parts 
by weight of additives, and water comprising the balance. Preferably, the 
detergent according to the first embodiment contains, by weight, 10 to 55 
parts of the three component mixture. More preferably, the detergent 
contains, by weight, 20 to 50 parts of the three component mixture. 
In a second embodiment of the invention, the detergent contains, by weight, 
5 to 60 parts of a three component mixture that incorporates an anionic 
surfactant, a nonionic surfactant and an alkyl ethoxylated carboxylate; 0 
to 20 parts by weight of additives, and water comprising the balance. 
Preferably, the detergent according to the second embodiment contains, by 
weight, 10 to 55 parts of the three component mixture. More preferably, 
the detergent contains, by weight, 20 to 50 parts of the three component 
mixture. 
In both embodiments, the anionic and nonionic surfactants can be, but are 
not necessarily, the same. 
ANIONIC SURFACTANT 
Most anionic surfactants can be broadly described as the water-soluble 
salts, particularly the alkali metal, alkaline earth metal, ammonium and 
amine salts of organic sulfuric reaction products having in their 
molecular structure an alkyl radical containing from about 8 to about 22 
carbon atoms and a sulfonic acid radical. In particular, the anionic 
surfactants useful in the present invention are the sodium and magnesium 
paraffin sulfonates in which the alkyl group contains from about 10 to 
about 20 carbon atoms. 
Alkane or paraffin sulfonates have previously been used as anionic 
detergent constituents of various detergent compositions. Methods for the 
manufacture of such sulfonates are known in the art. Typically, all that 
is usually involved is the reaction of a particular hydrocarbon or 
hydrocarbon mixture with sulfur dioxide, oxygen and a sulfonation reaction 
initiator. Normally, it is desirable to produce the sulfonate as the 
monosulfonate, having no unreacted starting hydrocarbon or having a 
limited proportion thereof present, and with little or no inorganic salt 
byproduct. Similarly, the proportions of disulfonate or higher sulfonated 
material will be minimized but some may be present. 
The alkane sulfonates which are a component of the present invention are 
the water soluble salts of the corresponding sulfonic acids wherein the 
salt-forming cation a solubilizing metal, an alkaline earth metal such as 
magnesium, preferably an alkali metal such as sodium or potassium, or 
ammonium or lower alkanolammonium, such as triethanolammonium, 
monoethanolammonium, or diisopropanolammonium. The lower alkanol of such 
alkanolammonium will normally be of 2 to 4 carbon atoms and is preferably 
ethanol. 
There may be present with the monosulfonate a corresponding disulfonate as 
well as unreacted alkane and by-product sulfate, usually a soluble 
inorganic sulfate such as sodium, potassium or other cationic sulfate. 
In particular, the alkane sulfonates useful in the present invention 
include those containing from 10 to 20 carbon atoms, particularly from 0 
to 16 carbon atoms. Most preferably, they contain from 13 to 17 carbon 
atoms. 
Although the alkyl group can be straight or branched, a straight chain is 
preferred. In addition, the sulfonate is preferably joined to any 
secondary carbon atom, i.e., the sulfonate is not terminally joined. In 
accordance with the most preferred embodiment, the alkane sulfonate is a 
linear non-terminal secondary C.sub.13 -C.sub.17 alkyl monosulfonate with 
a minor portion of disulfonate and sodium sulfate such as can be obtained 
from Hoechst-Celanese under the trade name Hostapur SAS-30, 60, or 93. 
The amount of anionic surfactant present in the three component mixture, 
according to the first embodiment, ranges from about 2.5% to about 95% 
preferably from about 20% to about 90%. More preferably, the anionic 
surfactant is present at about 40% to about 85% with from about 50% to 
about 80% being particularly preferred. 
The amount of anionic surfactant present in the three component mixture, 
according to the second embodiment, ranges from about 5% to about 98% 
preferably from about 25% to about 93%. More preferably, the anionic 
surfactant is present at about 50% to about 88% with from about 60% to 
about 85% being particularly preferred. 
NONIONIC SURFACTANT 
The nonionic surfactant operable in the present invention is an amide. In 
particular, the amide type of nonionic surfactant includes the ammonia, 
monoalkanol, and dialkanol amides of fatty acids having an acyl moiety of 
from about 8 to about 18 carbon atoms where the alkanol has from 2 to 4 
carbon atoms and is represented by the general formula: 
EQU R.sub.1 --CO--N(H).sub.m-1 (R.sub.2 OH).sub.3-m 
wherein R.sub.1 is a saturated or unsaturated aliphatic hydrocarbon radical 
having from 8 to 18, preferably from 12 to 14 carbon atoms; R.sub.2 is a 
methylene, ethylene, or propylene group; and m is 1, 2, or 3, preferably 1 
or 2, most preferably 1. 
Examples of amides that are useful in the present invention, include but 
are not limited to, the mono and diethanol coconut, lauric, and myristic 
fatty acid amides. The acyl moieties may be derived from naturally 
occurring glycerides, e.g., coconut oil, palm oil, soybean oil and tallow, 
but can be derived synthetically, e.g., by the oxidation of petroleum, or 
hydrogenation of carbon monoxide by the Fischer-Tropsch process. 
The monoethanolamides and diethanolamides of C.sub.12 -C.sub.14 fatty acids 
are preferred. The diethanolamide of coconut fatty acid such as Ninol 
40-C0 from Stepan Chemical Co. is particularly preferred. 
The amount of nonionic surfactant present in the three component mixture, 
according to the first embodiment, ranges from about 2.5% to about 95% 
preferably from about 5% to about 75%. More preferably, the nonionic 
surfactant is present at about 5% to about 55% with from about 10% to 
about 40% being particularly preferred. 
The amount of nonionic surfactant present in the three component mixture, 
according to the second embodiment, ranges from about 1% to about 94% 
preferably from about 5% to about 60%. More preferably, the anionic 
surfactant is present at about 10% to about 40% with from about 15% to 
about 37% being particularly preferred. 
AMIDO AMINE OXIDE 
As described above, the three component mixture according to the first 
embodiment contains an anionic surfactant, a nonionic surfactant, and an 
amido amine oxide. In particular, the amido amine oxide comprises 
compounds and mixtures of compounds having the formula: 
##STR1## 
wherein R.sup.3 is a C.sub.8-18 alkyl, R.sup.4 is a C.sub.2-4 alkyl, and 
R.sup.5 and R.sup.6 are a C.sub.1-5 alkyl or hydroxy alkyl. Preferably, 
R.sup.3 is a C.sub.12-14 alkyl, R.sup.4 is ethyl or propyl, and R.sup.5 
and R.sup.6 are methyl or ethyl. 
Examples of amido amine oxides which may be useful in the present invention 
include, but are not necessarily limited to, babassuamidopropyl amine 
oxide, cocamidopropyl amine oxide, isostearylamidopropyl amine oxide, 
isostearylamidopropyl morpholine oxide, lauramidopropyl amine oxide, 
minkamidopropyl amine oxide, oleoamidopropyl amine oxide, olivamidopropyl 
amine oxide, sesamidopropyl amine oxide, stearamidopropyl amine oxide, and 
wheat germ amidopropyl amine oxide. A particularly preferred amido amine 
oxide is Varox 1770 from, Sherex, wherein R.sup.3 is a C.sub.12 alkyl, 
R.sup.4 is propyl, and R.sup.5, R.sup.6 are methyl. 
The amount of the amido amine oxide present in the three component mixture 
ranges from about 2.5% to about 95% preferably from about 2.5% to about 
60%. More preferably, the amido amine oxide is present at about 5% to 
about 40% with from about 5% to about 30% being particularly preferred. 
ALKYL ETHOXYLATED CARBOXYLATE 
As described above, the three component mixture according to the second 
embodiment contains an anionic surfactant, a nonionic surfactant, and an 
alkyl ethoxylated carboxylate. In particular, the alkyl ethoxylated 
carboxylate comprises compounds and mixtures of compounds having the 
formula: 
EQU R.sup.7 (OC.sub.2 H.sub.4).sub.n --OCH.sub.2 COO.sup.- M.sup.+ 
wherein R.sup.7 is a C.sub.4-18 alkyl, n is from about 3 to about 20, and M 
is hydrogen, a solubilizing metal, preferably an alkali metal such as 
sodium or potassium, or ammonium or lower alkanolammonium, such as 
triethanolammonium, monoethanolammonium, or diisopropanolammonium. The 
lower alkanol of such alkanolammonium will normally be of 2 to 4 carbon 
atoms and is preferably ethanol. Preferably, R.sup.7 is a C.sub.12-15 
alkyl, n is from about 7 to about 13, and M is an alkali metal. 
Examples of alkyl ethoxylated carboxylates that may be useful in the 
present invention include, but are not necessarily limited to, sodium 
buteth-3 carboxylate, sodium hexeth-4 carboxylate, sodium laureth-5 
carboxylate, sodium laureth-6 carboxylate, sodium laureth-8 carboxylate, 
sodium laureth-11 carboxylate, sodium laureth-13 carboxylate, sodium 
trideceth-3 carboxylate, sodium trideceth-6 carboxylate, sodium 
trideceth-7 carboxylate, sodium trideceth-19 carboxylate, sodium 
capryleth-4 carboxylate, sodium capryleth-6 carboxylate, sodium 
capryleth-9 carboxylate, sodium capryleth-13 carboxylate, sodium 
ceteth-13 carboxylate, sodium C.sub.12-15 pareth-6 carboxylate, sodium 
C.sub.12-15 pareth-7 carboxylate, sodium C.sub.14-15 pareth-8 carboxylate, 
isosteareth-6 carboxylate as well as the acid form. Sodium laureth-8 
carboxylate, sodium laureth-13 carboxylate, pareth-25-7 carboxylic acid 
are preferred. A particularly preferred sodium laureth-13 carboxylate can 
be obtained from Finetex under the trade name Surfine WLL and from Sandoz 
under the trade name Sandopan LS-24. 
The amount of alkyl ethoxylated carboxylate present in the three component 
mixture ranges from about 1% to about 30% preferably from about 2% to 
about 15%. More preferably, the alkyl ethoxylated carboxylate is present 
at about 2% to about 10% with from about 3% to about 10% being 
particularly preferred. 
WATER 
Water comprises the balance of the detergent composition. Accordingly, the 
compositions of both the first and second embodiment can contain, per 100 
parts of the detergent composition, from about 40 to about 95 parts of 
water. 
OPTIONAL INGREDIENTS 
Since the detergent compositions of the present invention are in liquid 
form, stabilizing agents can be included to achieve the desired phase 
stability, viscosity, pH balance and other desired composition 
characteristics. For example, short chain water soluble alcohols or 
glycols, preferably having from 2 to 6 carbon atoms can be added. Up to 
about 10% of propylene glycol, butylene glycol, hexylene glycol and 
mixtures thereof, are preferred. 
Commonly used hydrotropes can include conventional lower alkylaryl 
sulfonates such as sodium and potassium, toluene sulfonate, xylene 
sulfonate, benzene sulfonate, and cumene sulfonate. Sodium and potassium 
toluene sulfonate, sodium and potassium xylene sulfonate and related 
compounds and can be used to achieve the desired product phase stability, 
viscosity and yield value. Sodium xylene sulfonate up to a level of about 
5% is useful. 
Alkalinity sources, pH buffering agents, and pH control agents such as 
alkali metal carbonates and bicarbonates, monoethanolamine, 
triethanolamine, tris hydroxy methylamine, and alkali metal hydroxides can 
also be used. The mono, di, and triethanolamines are preferred and can be 
added up to a level of about 5%. 
Builders may also be added, although they have limited value in dishwashing 
compositions. Either inorganic or organic builders may be used alone or in 
combination with themselves. Examples of such builders are alkali metal 
carbonates, phosphates, polyphosphates, and silicates. 
Sequestrants can also be incorporated into the compositions. Examples are 
the alkali metal polycarboxylates, such as sodium and potassium citrate, 
sodium and potassium tartrate, citric acid, sodium and potassium 
ethylenediaminetetraacetate (EDTA), triacetates, sodium and potassium 
nitrilotriacetates (NTA), and mixtures thereof. Up to about 10% of citric 
acid can be used. 
In addition, the detergent compositions of the present invention can 
contain, if desired, other optional ingredients including any of the usual 
adjuvants, diluents, and additives such as perfumes, enzymes, dyes, 
anti-tarnishing agents, antimicrobial agents, abrasives, hand softening 
agents such as aloe vera gel, water soluble salts of alkaline earth metals 
such as magnesium sulfate, and the like without detracting from the 
advantageous properties of the compositions. 
The compositions can contain up to about 20% of these optional ingredients. 
The following examples are given to illustrate the compositions of the 
invention. In the examples the abbreviations used have the following 
meanings. 
______________________________________ 
Abbreviation Description 
______________________________________ 
SAS Secondary C.sub.13-17 alkane sulfonate 
CDEA Coconut diethanolamide 
AAO Cocamidopropyl amine oxide 
AO.sup.1 Coco amine oxide 
AO.sup.2 Lauryl amine oxide 
Pareth-25-7 Pareth-25-7 carboxylic acid 
Laureth-8 Laureth-8 carboxylic acid 
Na Laureth-13 Sodium Laureth-13 carboxylate 
Glycol Propylene glycol 
SXS Sodium xylene sulfonate 
______________________________________ 
EXAMPLE 1 
The following liquid detergent compositions were prepared. 
______________________________________ 
A B C D 
______________________________________ 
SAS 31.5 31.5 31.5 31.5 
CDEA 13.5 9.0 9.9 9.0 
AAO -- 4.5 -- -- 
AO.sup.1 -- -- 4.5 -- 
AO.sup.2 -- -- -- 4.5 
Glycol 5.0 5.0 5.0 5.0 
SXS 2.0 2.0 2.0 2.0 
Additional .about.1 
.about.1 .about.1 
.about.1 
optional 
ingredients 
Water remainder 
______________________________________ 
Composition B is within the scope of the present invention. Compositions A, 
C, and D may be representative of presently used dishwashing detergent 
compositions and are outside the scope of the present invention. 
The "miniplate dishwashing test" was used to evaluate the performance of 
the compositions. In the "miniplate" test, small plates having a standard 
amount of a standard grease coating applied thereto are washed in warm 
water, e.g., at 120.degree. F. at the beginning of the test, at different 
hardnesses and with different concentrations of liquid detergent and the 
number of plates washed until the foam disappears are counted. 
Each of the compositions in Example 1 were evaluated at varying water 
hardness levels using the "miniplate" test where the compositions were 
used at a level of 0.075%. The following results were observed: 
TABLE 1 
______________________________________ 
Dishwashing Performance (No. of Plates) 
WATER HARDNESS (ppm) 
COMPOSITION 0 15 150 300 450 
______________________________________ 
A 6.5 9.0 10.0 8.5 6.0 
B 8.1 9.7 11.2 10.5 9.5 
C 9.0 -- 7.25 -- -- 
D 6.0 8.5 7.5 -- -- 
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EXAMPLE 2 
The following liquid detergent compositions were prepared. 
______________________________________ 
E F G H I 
______________________________________ 
SAS 31.5 30.1 28.7 30.1 30.1 
CDEA 13.5 12.9 12.3 12.9 12.9 
Pareth-25-7 -- 2.0 4.0 -- -- 
Laureth-8 -- -- -- 2.0 -- 
Na Laureth-13 
-- -- -- -- 2.0 
Glycol 5.0 5.0 5.0 5.0 5.0 
SXS 2.0 2.0 2.0 2.0 2.0 
Additional .about.1 .about.1 
.about.1 
.about.1 
.about.1 
optional 
ingredients 
Water remainder 
______________________________________ 
Compositions F, G, H, and I are within the scope of the present invention. 
Composition E may be representative of presently used dishwashing 
detergent compositions and is outside the scope of the present invention. 
Each of the compositions in Example 2 were evaluated at varying water 
hardness levels using the "miniplate" test where the compositions were 
used at a level of 0.075%. The following results were observed. 
TABLE 2 
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Dishwashing Performance (No. of Plates) 
WATER HARDNESS (ppm) 
COMPOSITION 
0 5 15 50 150 300 450 
______________________________________ 
E 5.5 7.5 8.75 
10.0 9.6 8.0 6.125 
F 5.5 -- 8.0 9.5 9.5 9.5 9.0 
G 5.5 7.0 9.5 9.0 10.0 10.0 9.0 
H 4.0 -- -- 10.0 9.5 9.25 8.0 
I 5.75 -- 8.0 10.0 10.5 9.75 9.0 
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EXAMPLE 3 
The following liquid detergent compositions were prepared where composition 
J is the most preferred embodiment of a liquid detergent composition 
according to the first embodiment of the invention and composition K is 
the most preferred embodiment of a liquid detergent according to the 
second embodiment of the invention. 
______________________________________ 
J K 
______________________________________ 
SAS 31.5 30.1 
CDEA 9.0 12.9 
AAO 4.5 -- 
Na Laureth-13 -- 1.9 
Glycol 5.0 2.5 
SXS 0.4 2.0 
Additional 0.66 1.06 
optional 
ingredients 
Water remainder 
______________________________________ 
The key to obtaining the desired detergency and foam stability appears to 
depend on the proper selection and relative amounts of the ingredients in 
the three component mixtures. 
Of course, it should be understood that a wide range of changes and 
modifications can be made to the embodiments described above. It is 
therefore intended that the foregoing description illustrates rather than 
limits this invention, and that it is the following claims, including all 
equivalents, which define this invention.