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Description  |
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TECHNICAL FIELD
The present invention relates to acidic rinsing (rinse aid) compositions,
particularly acidic rinsing compositions containing an organo
aminophosphonic acid component.
BACKGROUND OF THE INVENTION
Rinse aid compositions designed for use in automatic dishwasher machines
are well known. These compositions are added during the rinsing cycle of
the machine, separately from the detergent composition employed in the
main wash cycle(s). The ability to enhance rinsing, and in particular the
ability to prevent spot and film formation are common measures of rinse
aid performance.
Rinse aid compositions typically contain components such as nonionic
surfactants and/or hydrotropes which aid the wetting of the items in the
rinse, thereby improving the efficacy of the rinsing process. These
surfactants, and rinse aid compositions in general, are not designed for
the achievement of a primary soil removal purpose.
The general problem of the formation of deposits as spots and films on the
articles in the wash/rinse, and on the dishwasher machine parts is well
known in the art.
Whilst the general problem of deposit formation is known, a full
understanding of the many facets of the problem is however still an active
area of research.
A range of deposit types can be encountered. The redoposition of soils or
the breakdown products thereof, which have previously been removed from
the soiled tableware in the washload, provides one deposit type. Insoluble
salts such as calcium carbonate, calcium fatty acid salts (lime soaps), or
certain silicate salts are other common deposit types. Composite deposit
types are also common. Indeed, once an initial minor deposit forms it can
act as a "seeding centre" for the formation of a larger, possibly
composite, deposit structure.
Deposit formation can occur on a range of commonly encountered substrate
surfaces including plastic, glass, metal and china surfaces. Certain
deposit types however, show a greater propensity to deposit on certain
substrates. For example, lime soap deposit formation tends to be a
particular problem on plastic substrates.
The formation of insoluble carbonate, especially calcium carbonate,
deposits is a particular problem in the machine dishwashing art. There is
a general appreciation in the art, as represented for example by
EP-A-364,067 in the name of Clorox, CH-A-673,033 in the name of Cosmina,
and EP-A-551,670 in the name of Unilever, that calcium carbonate deposit
formation is a particular problem when non-phosphate containing detergent
formulations are employed. In general, this can be explained by the
slightly inferior builder capacity of the typically employed non-phosphate
builder systems in comparison to phosphate builder formulations. The
problem of calcium carbonate deposit formation is understood to be
especially apparent when these formulations contain a carbonate builder
component, as for example is essential to the compositions taught by
EP-A-364,067.
The Applicants have now found that the problem of CaCO.sub.3 deposit
formation can exist even in the absence of a carbonate builder component
in the machine dishwashing detergent formulation, and especially when that
formulation contains no phosphate builder components. It has also been
established that the problem is most apparent when highly alkaline
formulations, such as those of pH of 9.8 and above, are employed.
The naturally sourced, inlet water to the dishwasher machine can be a
sufficient source of Ca.sup.2+ and Mg.sup.2+ ions and CO.sub.3.sup.2-
/HCO.sub.3.sup.- ions to make deposit formation a problem. Whilst the salt
softening system, through which the inlet water will pass prior to entry
into the main cavity of the dishwasher machine, can be efficient at
removing the naturally present Ca.sup.2+ and Mg.sup.2+ ions it is
inefficient at removing the CO.sub.3.sup.2- /HCO.sub.3.sup.- ions which
therefore enter into the wash/rinse solution.
The Applicants have now established that both the levels of Ca.sup.2+
/Mg.sup.2+ hardness ions and the levels of CO.sub.3.sup.2-
/HCO.sub.3.sup.- ions in the wash/rinse water of the dishwasher machine
are factors controlling calcium carbonate deposit formation. Critical
levels of both components must be exceeded for deposit formation to occur.
These critical levels are to an extent interdependent. Thus, even in
wash/rinse solutions containing high levels of one component, deposit
formation will not occur in the absence of the critical level of the other
component.
The Applicants have further established that the formation of calcium
carbonate deposits occurs most noticeably in the rinse cycle of the
dishwasher machine. Deposit build up is most apparent on the heater
element of the dishwasher machine.
The Applicants have found that the problem of calcium carbonate deposit
formation may be effectively ameliorated by the inclusion of an organo
aminophosphonic acid component into a rinse aid formulation. Said rinse
aid formulation is of particular utility when used in combination with
non-phosphate containing detergent formulations which, as previously
mentioned, tend to be more susceptible to the problem of calcium carbonate
deposit formation.
The Applicants have also found that carboxylates and polycarboxylates,
particularly citrates, are especially useful components of the
compositions of the invention because of their magnesium binding capacity
which tends to prevent the formation of insoluble magnesium salts, such as
magnesium silicate on the articles in the wash. Such polycarboxylates also
provide calcium binding capacity to the compositions, thus contributing
further to the prevention of the formation of calcium salt deposits.
The Applicants have also found that the more effective control of calcium
carbonate deposition can also lead to benefits in the prevention of the
formation of other deposit types, particularly lime soap deposits and
silicate deposits.
Lime soap deposits are most commonly encountered when the washload contains
fatty soils, which naturally contain levels of free fatty acids, and when
lipolytic enzymes are components of the formulation. Lipolytic enzymes
catalyse the degradation of fatty soils into free fatty acids and
glycerol. Silicate is a common component of machine dishwashing
formulations, where it is added for its china care capability. It is the
Applicant's finding that by preventing the formation of calcium carbonate
deposit "seeding centres", the build up of other deposit types from these
"seeding centres" is also prevented.
The Applicants have found that certain resistant soils/stains, especially
bleachable soils/stains, most especially tea stains, can remain on
tableware, especially chinaware at the end of the wash cycle of an
automatic dishwashing machine.
The Applicants have also found that said resistant soils/stains, especially
tea stains on chinaware, may `recolourise` under the conditions of the
rinse, thereby enhancing the colour of the soils/stains.
The Applicants have found that the inclusion of said aminophosphonic acid
component into said rinse aid formulation enhances the removal of said
resistant soils/stains from the tableware during the rinse cycle. The
problem of stain recolourisation is thus also avoided. The removal of tea
stains from chinaware is particularly enhanced.
SUMMARY OF THE INVENTION
There is provided a rinse aid composition containing an organo
aminophosphonic acid or its salts or complexes.
The pH of said composition as a 1% solution in distilled water at
20.degree. C. is preferably less than 7.
DETAILED DESCRIPTION OF THE INVENTION
Organo aminophosphonic acid
An essential component of the compositions in accord with the invention is
an organo aminophosphonic acid or one of its salts or complexes. By organo
aminophosphonic acid component it is meant herein an organic compound
comprising at least one phosphonic acid group, and at least one amino
group.
The organo aminophosphonic acid component is preferably present at a level
of from 0.005% to 20%, more preferably from 0.1% to 15%, most preferably
from 0.5% to 10% by weight of the compositions.
The organo aminophosphonic acid component may be present in its acid form
or in the form of one of its salts or complexes with a suitable counter
cation, and reference herein to the acid component implicitly includes
reference to the salts or complexes. Preferably any salts/complexes are
water soluble, with the alkali metal and alkaline earth metal
salts/complexes being especially preferred.
Suitable organo aminophosphonic acid components for use herein include the
amino alkylene poly (alkylene phosphonic acids) and nitrilo trimethylene
phosphonic acids. Preferred are diethylene triamine penta (methylene
phosphonic acid) and hexamethylene diamine tetra (methylene phosphonic
acid).
pH of the compositions
In a highly preferred aspect of the invention the compositions have a pH as
a 1% solution in distilled water at 20.degree. C. of less than 7,
preferably from 0.5 to 6.5, most preferably from 1.0 to 5.0.
The pH of the compositions may be adjusted by the use of various pH
adjusting agents. Preferred acidification agents include inorganic and
organic acids including, for example, carboxylate acids, such as citric
and succinic acids, polycarboxylate acids, such as polyacrylic acid, and
also acetic acid, boric acid, malonic acid, adipic acid, fumaric acid,
lactic acid, glycolic acid, tartaric acid, tartronic acid, maleic acid,
their derivatives and any mixtures of the foregoing. Bicarbonates,
particularly sodium bicarbonate, are useful pH adjusting agents herein. A
highly preferred acidification acid is citric acid which has the advantage
of providing builder capacity to the wash solution.
Organo diphosphonic acid
A preferred component of the detergent compositions in accord with the
invention is an organo diphosphonic acid or one of its salts or complexes.
Said organo diphosphonic acid may act in combination with the organo
aminophosphonic acid component to further enhance the prevention of
calcium carbonate deposit formation.
The organo diphosphonic acid component is preferably present at a level of
from 0.005% to 20%, more preferably from 0.1% to 15%, most preferably from
0.5% to 10% by weight of the compositions.
By organo diphosphonic acid it is meant herein an organo diphosphonic acid
which does not contain nitrogen as part of its chemical structure. This
definition therefore excludes the organo aminophosphonates.
The organo diphosphonic acid component may be present in its acid form or
in the form of one of its salts or complexes with a suitable counter
cation. Preferably any salts/complexes are water soluble, with the alkali
metal and alkaline earth metal salts/complexes being especially preferred.
The organo diphosphonic acid is preferably a C.sub.1 -C.sub.4 diphosphonic
acid, more preferably a C.sub.2 diphosphonic acid, such as ethylene
diphosphonic acid, or most preferably ethane 1-hydroxy-1,1-diphosphonic
acid (HEDP).
Additional heavy metal ion sequestrants
Additional heavy metal ion sequestrants are useful components herein. By
heavy metal ion sequestrants it is meant components which act to sequester
(chelate) heavy metal ions. These components may also have calcium and
magnesium chelation capacity, but preferentially they bind heavy metal
ions such as iron, manganese and copper.
Additional heavy metal ion sequestrants are preferably present at a level
of from 0.005% to 20%, more preferably from 0.1% to 10%, most preferably
from 0.2% to 5% by weight of the compositions.
Heavy metal ion sequestrants, which are acidic in nature, having for
example carboxylic acid functionalities, may be present either in their
acid form or as a complex/salt with a suitable counter cation such as an
alkali or alkaline metal ion, ammonium, or substituted ammonium ion, or
any mixtures thereof. Preferably any salts/complexes are water soluble.
The molar ratio of said counter cation to the heavy metal ion sequestrant
is preferably at least 1:1.
Other suitable additional heavy metal ion sequestrants for use herein
include nitrilotriacetic acid and polyaminocarboxylic acids such as
ethylenediaminotetracetic acid, ethylenetriamine pentacetic acid, or
ethylenediamine disuccinic acid. Especially preferred is
ethylenediamine-N,N'-disuccinic acid (EDDS), most preferably present in
the form of its S,S isomer, which is preferred for its biodegradability
profile.
Still other suitable additional heavy metal ion sequestrants for use herein
are iminodiacetic acid derivatives such as 2-hydroxyethyl diacetic acid or
glyceryl imino diacetic acid, described in EPA 317 542 and EPA 399 133.
Low molecular weight acrylic acid containing organic polymer
The compositions in accord with the invention may contain as a preferred
component an organic polymer containing acrylic acid or its salts having
an average molecular weight of less than 15,000, hereinafter referred to
as low molecular weight acrylic acid containing polymer. Such low
molecular weight acrylic acid containing polymers may act as CaCO.sub.3
dispersants, and thus further enhance the CaCO.sub.3 deposition prevention
capability of the compositions herein.
The low molecular weight acrylic acid containing polymer has, an average
molecular weight of less than 15,000, preferably from 500 to 12,000, more
preferably from 1,500 to 10,000, most preferably from 2,500 to 9,000.
The low molecular weight acrylic acid containing organic polymer is
preferably present at a level of from 0.005% to 20%, more preferably from
0.1% to 10%, most preferably from 0.2% to 5% by weight of the
compositions.
The low molecular weight acrylic acid containing polymer may be either a
homopolymer or a copolymer including the essential acrylic acid or acrylic
acid salt monomer units. Copolymers may include essentially any suitable
other monomer units including modified acrylic, fumaric, maleic, itaconic,
aconitic, mesaconic, citraconic and methylenemalonic acid or their salts,
maleic anhydride, acrylamide, alkylene, vinylmethyl ether, styrene and any
mixtures thereof.
Preferred commercially available low molecular weight acrylic acid
containing homopolymers include Sokalan PA30, PA20, PA15 and PA10 by BASF
GmbH, and those sold under the tradename Acusol 45N by Rohm and Haas.
Preferred low molecular weight acrylic acid containing copolymers include
those which contain as monomer units: a) from about 90% to about 10%,
preferably from about 80% to about 20% by weight acrylic acid or its salts
and b) from about 10% to about 90%, preferably from about 20% to about 80%
by weight of a substituted acrylic monomer or its salts having the general
formula --[CR.sub.2 --CR.sub.1 (CO--O--R.sub.3)]-- wherein at least one of
the substituents R.sub.1, R.sub.2 or R.sub.3, preferably R.sub.1 or
R.sub.2 is a 1 to 4 carbon alkyl or hydroxyalkyl group, R.sub.1 or R.sub.2
can be a hydrogen and R.sub.3 can be a hydrogen or alkali metal salt. Most
preferred is a substituted acrylic monomer wherein R.sub.1 is methyl,
R.sub.2 is hydrogen. The most preferred copolymer of this type has a
molecular weight of 3500 and contains 60% to 80% by weight of acrylic acid
and 40% to 20% by weight of methyl acrylic acid.
Preferred commercially available low molecular weight acrylic acid
containing copolymers include those sold under the tradename Sokalan CP10
by BASF.
Other suitable polyacrylate/modified polyacrylate copolymers include those
copolymers of unsaturated aliphatic carboxylic acids disclosed in U.S.
Pat. Nos. 4,530,766, and 5,084,535 which have a molecular weight of less
than 15,000 in accordance with the invention.
Additional organic polymeric compound
Certain additional organic polymeric compounds may be added to the rinse
aid compositions of the invention, however, in certain cases their
presence is desirably minimized. By additional organic polymeric compounds
it is meant essentially any polymeric organic compounds commonly used as
dispersants, anti-redeposition and soil suspension agents in detergent
compositions, which do not fall within the definition of low molecular
weight acrylic acid containing polymers given hereinbefore.
Additional organic polymeric compound may be incorporated into the rinse
aid compositions of the invention at a level of from 0.05% to 30%,
preferably from 0.5% to 15%, most preferably from 1% to 10% by weight of
the compositions.
Examples of additional organic polymeric compounds whose presence is
desirably minimized, and which are preferably not present, include the
water soluble organic homo- or co-polymeric polycarboxylic acids or their
salts in which the polycarboxylic acid comprises at least two carboxyl
radicals separated from each other by not more than two carbon atoms.
Polymers of the latter type are disclosed in GB-A-1,596,756. Examples of
such salts are the copolymers of polyacrylate with maleic anhydride having
a molecular weight of from 20,000 to 150,000, especially about 40,000 to
80,000.
The polyamino compounds are useful herein including those derived from
aspartic acid such as those disclosed in EP-A-305282, EP-A-305283 and
EP-A-351629.
Other additional organic polymeric compounds suitable herein include
cellulose derivatives such as methylcellulose, carboxymethylcellulose and
hydroxyethylcellulose.
Further useful additional organic polymeric compounds are the polyethylene
glycols, particularly those of molecular weight 1000-10000, more
particularly 2000 to 8000 and most preferably about 4000.
Detergent Builder System
A highly preferred component of the rinsing compositions of the present
invention is a detergent builder system which is preferably present at a
level of from 0.5% to 60% by weight, more preferably from 1% to 30% by
weight, most preferably from 2% to 20% weight of the composition.
The detergent builder system is preferably water-soluble, and preferably
contains a carboxylate or polycarboxylate builder containing from one to
four carboxy groups, particularly selected from monomeric polycarboxylates
or their acid forms, homo or copolymeric polycarboxylic acids or their
salts in which the polycarboxylic acid comprises at least two carboxylic
radicals separated from each other by not more that two carbon atoms.
The detergent builder system can contain alkali metal, ammonium or
alkanonammonium salts of bicarbonates, borates, phosphates, and mixtures
of any of the foregoing.
Preferably, the detergent builder system contains no phosphate builder
compound.
Carboxylate or polycarboxylate builder
Suitable water-soluble monomeric or oligomeric carboxylate builders can be
selected from a wide range of compounds but such compounds preferably have
a first carboxyl logarithmic acidity/constant (pK.sub.1) of less than 9,
preferably of between 2 and 8.5, more preferably of between 4 and 7.5.
The carboxylate or polycarboxylate builder can be momomeric or oligomeric
in type although monomeric polycarboxylates are generally preferred for
reasons of cost and performance. Monomeric and oligomeric builders can be
selected from acyclic, alicyclic, heterocyclic and aromatic carboxylates.
Suitable carboxylates containing one carboxy group include the water
soluble salts of lactic acid, glycolic acid and ether derivatives thereof
as disclosed in Belgian Patent Nos. 831,368, 821,369 and 821,370.
Polycarboxylates containing two carboxy groups include the water-soluble
salts of succinic acid, malonic acid, (ethylenedioxy) diacetic acid,
maleic acid, diglycolic acid, tartaric acid, tartronic acid and fumaric
acid, as well as the ether carboxylates described in German
Offenlegenschrift 2,446,686, and 2,446,687 and U.S. Pat. No. 3,935,257 and
the sulfinyl carboxylates described in Belgian Patent No. 840,623.
Polycarboxylates containing three carboxy groups include, in particular,
water-soluble citrates, aconitrates and citraconates as well as succinate
derivatives such as the carboxymethyloxysuccinates described in British
Patent No. 1,379,241, lactoxysuccinates described in British Patent No.
1,389,732, and aminosuccinates described in Netherlands Application
7205873, and the oxypolycarboxylate materials such as 2-oxa-1,1,3-propane
tricarboxylates described in British Patent No. 1,387,447.
Polycarboxylates containing four carboxy groups include oxydisuccinates
disclosed in British Patent No. 1,261,829, 1,1,2,2-ethane
tetracarboxylates, 1,1,3,3-propane tetracarboxylates and 1,1,2,3-propane
tetracarboxylates. Polycarboxylates containing sulfo substituents include
the sulfosuccinate derivatives disclosed in British Patent Nos. 1,398,421
and 1,398,422 and in U.S. Pat. No. 3,936,448, and the sulfonated pyrolysed
citrates described in British Patent No. 1,439,000.
Alicyclic and heterocyclic polycarboxylates include
cyclopentane-cis,cis,cis-tetracarboxylates, cyclopentadienide
pentacarboxylates, 2,3,4,5-tetrahydrofuran - cis, cis,
cis-tetracarboxylates, 2,5-tetrahydrofuran - cis - dicarboxylates,
2,2,5,5-tetrahydrofuran - tetracarboxylates, 1,2,3,4,5,6-hexane -
hexacarboxylates and carboxymethyl derivatives of polyhydric alcohols such
as sorbitol, mannitol and xylitol. Aromatic polycarboxylates include
mellitic acid, pyromellitic acid and the phthalic acid derivatives
disclosed in British Patent No. 1,425,343.
Of the above, the preferred polycarboxylates are hydroxycarboxylates
containing up to three carboxy groups per molecule, more particularly
citrates, especially sodium citrate.
The parent acids of the monomeric or oligomeric polycarboxylate chelating
agents or mixtures thereof with their salts, e.g. citric acid or
citrate/citric acid mixtures are also contemplated as components of
builder systems of the compositions in accordance with the present
invention.
Phosphate builder compound
Specific examples of phosphate builders are the alkali metal
tripolyphosphates, sodium, potassium and ammonium pyrophosphate, sodium
and potassium and ammonium pyrophosphate, sodium and potassium
orthophosphate, sodium polymeta/phosphate in which the degree of
polymerization ranges from about 6 to 21, and salts of phytic acid.
Preferably, no phosphate builder compound is present.
Surfactant system
A highly preferred component of the compositions of the invention is a
surfactant system comprising surfactant selected from anionic, cationic,
nonionic ampholytic and zwitterionic surfactants and mixtures thereof.
The surfactant system most preferably comprises low foaming nonionic
surfactant, selected for its wetting ability, preferably selected from
ethoxylated and/or propoxylated nonionic surfactants, more preferably
selected from nonionic ethoxylated/propoxylated fatty alcohol surfactants.
When the surfactant system comprises low foaming nonionic surfactant the
compositions preferably contain no additional suds suppressor component,
such as silicone suds suppressors as can be found in certain machine
dishwashing detergent compositions.
The surfactant system is typically present at a level of from 0.5% to 40%
by weight, more preferably 1% to 30% by weight, most preferably from 5% to
20% by weight of the compositions.
Anionic surfactant
Essentially any anionic surfactants useful for detersive purposes can be
included in the compositions. These can include salts (including, for
example, sodium, potassium, ammonium, and substituted ammonium salts such
as mono-, di- and triethanolamine salts) of the anionic sulfate,
sulfonate, carboxylate and sarcosinate surfactants.
Other anionic surfactants include the isethionates such as the acyl
isethionates, N-acyl taurates, fatty acid amides of methyl tauride, alkyl
succinates and sulfosuccinates, monoesters of sulfosuccinate (especially
saturated and unsaturated C.sub.12 -C.sub.18 monoesters) diesters of
sulfosuccinate (especially saturated and unsaturated C.sub.6 -C.sub.14
diesters), N-acyl sarcosinates. Resin acids and hydrogenated resin acids
are also suitable, such as rosin, hydrogenated rosin, and resin acids and
hydrogenated resin acids present in or derived from tallow oil.
Anionic sulfate surfactant
Anionic sulfate surfactants suitable for use herein include the linear and
branched primary alkyl sulfates, alkyl ethoxysulfates, fatty oleyl
glycerol sulfates, alkyl phenol ethylene oxide ether sulfates, the C.sub.5
-C.sub.17 acyl-N-(C.sub.1 -C.sub.4 alkyl) and -N-(C.sub.1 -C.sub.2
hydroxyalkyl) glucamine sulfates, and sulfates of alkylpolysaccharides
such as the sulfates of alkylpolyglucoside (the nonionic nonsulfated
compounds being described herein).
Alkyl ethoxysulfate surfactants are preferably selected from the group
consisting of the C.sub.6 -C.sub.18 alkyl sulfates which have been
ethoxylated with from about 0.5 to about 20 moles of ethylene oxide per
molecule. More preferably, the alkyl ethoxysulfate surfactant is a C.sub.6
-C.sub.18 alkyl sulfate which has been ethoxylated with from about 0.5 to
about 20, preferably from about 0.5 to about 5, moles of ethylene oxide
per molecule.
Anionic sulfonate surfactant
Anionic sulfonate surfactants suitable for use herein include the salts of
C.sub.5 -C.sub.20 linear alkylbenzene sulfonates, alkyl ester sulfonates,
C.sub.6 -C.sub.22 primary or secondary alkane sulfonates, C.sub.6
-C.sub.24 olefin sulfonates, sulfonated polycarboxylic acids, alkyl
glycerol sulfonates, fatty acyl glycerol sulfonates, fatty oleyl glycerol
sulfonates, and any mixtures thereof.
Anionic carboxylate surfactant
Anionic carboxylate surfactants suitable for use herein include the alkyl
ethoxy carboxylates, the alkyl polyethoxy polycarboxylate surfactants and
the soaps (`alkyl carboxyls`), especially certain secondary soaps as
described herein.
Preferred alkyl ethoxy carboxylates for use herein include those with the
fomula RO(CH.sub.2 CH.sub.2 O).sub.x CH.sub.2 COO.sup.- M.sup.+ wherein R
is a C.sub.6 to C.sub.18 alkyl group, x ranges from 0 to 10, and the
ethoxylate distribution is such that, on a weight basis, the amount of
material where x is 0 is less than about 20%, and the amount of material
where x is greater than 7, is less than about 25%, the average x is from
about 2 to 4 when the average R is C.sub.13 or less, and the average x is
from about 3 to 10 when the average R is greater than C.sub.13, and M is a
cation, preferably chosen from alkali metal, alkaline earth metal,
ammonium, mono-, di-, and tri- ethanol-ammonium, most preferably from
sodium, potassium, ammonium and mixtures thereof with magnesium ions. The
preferred alkyl ethoxy carboxylates are those where R is a C.sub.12 to
C.sub.18 alkyl group.
Alkyl polyethoxy polycarboxylate surfactants suitable for use herein
include those having the formula RO--(CHR.sub.1 --CHR.sub.2 --O)--R.sub.3
wherein R is a C.sub.6 to C.sub.18 alkyl group, x is from 1 to 25, R.sub.1
and R.sub.2 are selected from the group consisting of hydrogen, methyl
acid radical, succinic acid radical, hydroxysuccinic acid radical, and
mixtures thereof, wherein at least one R.sub.1 or R.sub.2 is a succinic
acid radical or hydroxysuccinic acid radical, and R.sub.3 is selected from
the group consisting of hydrogen, substituted or unsubstituted hydrocarbon
having between 1 and 8 carbon atoms, and mixtures thereof.
Preferred soap surfactants are secondary soap surfactants which contain a
carboxyl unit connected to a secondary carbon. The secondary carbon can be
in a ring structure, e.g. as in p-octyl benzoic acid, or as in
alkyl-substituted cyclohexyl carboxylates. The secondary soap surfactants
should preferably contain no ether linkages, no ester linkages and no
hydroxyl groups. There should preferably be no nitrogen atoms in the
head-group (amphiphilic portion). The secondary soap surfactants usually
contain 11-13 total carbon atoms, although slightly more (e.g., up to 16)
can be tolerated, e.g. p-octyl benzoic acid.
The following general structures further illustrate some of the preferred
secondary soap surfactants:
A. A highly preferred class of secondary soaps comprises the secondary
carboxyl materials of the formula R.sup.3 CH(R.sup.4)COOM, wherein R.sup.3
is CH.sub.3 (CH.sub.2)x and R.sup.4 is CH.sub.3 (CH.sub.2)y, wherein y can
be 0 or an integer from 1 to 4, x is an integer from 4 to 10 and the sum
of (x+y) is 6-10, preferably 7-9, most preferably 8.
B. Another preferred class of secondary soaps comprises those carboxyl
compounds wherein the carboxyl substituent is on a ring hydrocarbyl unit,
i.e., secondary soaps of the formula R.sup.5 --R.sup.6 --COOM, wherein
R.sup.5 is C.sup.7 -C.sup.10, preferably C.sup.8 -C.sup.9, alkyl or
alkenyl and R.sup.6 is a ring structure, such as benzene, cyclopentane and
cyclohexane. (Note: R.sup.5 can be in the ortho, meta or para position
relative to the carboxyl on the ring.)
C. Still another preferred class of secondary soaps comprises secondary
carboxyl compounds of the formula CH.sub.3 (CHR).sub.k --(CH.sub.2).sub.m
--(CHR).sub.n --CH(COOM)(CHR).sub.o --(CH2).sub.p --(CHR).sub.q
--CH.sub.3, wherein each R is C.sub.1 -C.sub.4 alkyl, wherein k, n, o, q
are integers in the range of 0-8, provided that the total number of carbon
atoms (including the carboxylate) is in the range of 10 to 18.
In each of the above formulas A, B and C, the species M can be any
suitable, especially water-solubilizing, counterion.
Especially preferred secondary soap surfactants for use herein are
water-soluble members selected from the group consisting of the
water-soluble salts of 2-methyl-1-undecanoic acid, 2-ethyl-1-decanoic
acid, 2-propyl-1-nonanoic acid, 2-butyl-1-octanoic acid and
2-pentyl-1-heptanoic acid.
Alkali metal sarcosinate surfactant
Other suitable anionic surfactants are the alkali metal sarcosinates of
formula R--CON (R.sup.1) CH.sub.2 COOM, wherein R is a C.sub.5 -C.sub.17
linear or branched alkyl or alkenyl group, R.sup.1 is a C.sub.1 -C.sub.4
alkyl group and M is an alkali metal ion. Preferred examples are the
myristyl and oleyl methyl sarcosinates in the form of their sodium salts.
Nonionic surfactant
Essentially any anionic surfactants useful for detersive purposes can be
included in the compositions. Exemplary, non-limiting classes of useful
nonionic surfactants are listed below.
Nonionic polyhydroxy fatty acid amide surfactant
Polyhydroxy fatty acid amides suitable for use herein are those having the
structural formula R.sup.2 CONR.sup.1 Z wherein: R1 is H, C.sub.1 -C.sub.4
hydrocarbyl, 2-hydroxy ethyl, 2-hydroxy propyl, or a mixture thereof,
preferable C1-C4 alkyl, more preferably C.sub.1 or C.sub.2 alkyl, most
preferably C.sub.1 alkyl (i.e., methyl); and R.sub.2 is a C.sub.5
-C.sub.31 hydrocarbyl, preferably straight-chain C.sub.5 -C.sub.19 alkyl
or alkenyl, more preferably straight-chain C.sub.9 -C.sub.17 alkyl or
alkenyl, most preferably straight-chain C.sub.11 -C.sub.17 alkyl or
alkenyl, or mixture thereof; and Z is a polyhydroxyhydrocarbyl having a
linear hydrocarbyl chain with at least 3 hydroxyls directly connected to
the chain, or an alkoxylated derivative (preferably ethoxylated or
propoxylated) thereof. Z preferably will be derived from a reducing sugar
in a reductive amination reaction; more preferably Z is a glycityl.
Nonionic condensates of alkyl phenols
The polyethylene, polypropylene, and polybutylene oxide condensates of
alkyl phenols are suitable for use herein. In general, the polyethylene
oxide condensates are preferred. These compounds include the condensation
products of alkyl phenols having an alkyl group containing from about 6 to
about 18 carbon atoms in either a straight chain or branched chain
configuration with the alkylene oxide.
Nonionic ethoxylated alcohol surfactant
The alkyl ethoxylate condensation products of aliphatic alcohols with from
about 1 to about 25 moles of ethylene oxide are suitable for use herein.
The alkyl chain of the aliphatic alcohol can either be straight or
branched, primary or secondary, and generally contains from 6 to 22 carbon
atoms. Particularly preferred are the condensation products of alcohols
having an alkyl group containing from 8 to 20 carbon atoms with from about
2 to about 10 moles of ethylene oxide per mole of alcohol.
Nonionic ethoxylated/propoxylated fatty alcohol surfactant
The ethoxylated C.sub.6 -C.sub.18 fatty alcohols and C.sub.6 -C.sub.18
mixed ethoxylated/propoxylated fatty alcohols are highly preferred
surfactants for use herein, particularly where water soluble. Preferably
the ethoxylated fatty alcohols are the C.sub.10 -C.sub.18 ethoxylated
fatty alcohols with a degree of ethoxylation of from 3 to 50, most
preferably these are the C.sub.12 -C.sub.18 ethoxylated fatty alcohols
with a degree of ethoxylation from 3 to 40. Preferably the mixed
ethoxylated/propoxylated fatty alcohols have an alkyl chain length of from
10 to 18 carbon atoms, a degree of ethoxylation of from 3 to 30 and a
degree of propoxylation of from 1 to 10.
Nonionic EO/PO condensates with propylene glycol
The condensation products of ethylene oxide with a hydrophobic base formed
by the condensation of propylene oxide with propylene glycol are suitable
for use herein. The hydrophobic portion of these compounds preferably has
a molecular weight of from about 1500 to about 1800 and exhibits water
insolubility. Examples of compounds of this type include certain of the
commercially-available Pluronic.TM. surfactants, marketed by BASF.
Nonionic EO condensation products with propylene oxide/ethylene diamine
adducts
The condensation products of ethylene oxide with the product resulting from
the reaction of propylene oxide and ethylenediamine are suitable for use
herein. The hydrophobic moiety of these products consists of the reaction
product of ethylenediamine and excess propylene oxide, and generally has a
molecular weight of from about 2500 to about 3000. Examples of this type
of nonionic surfactant include certain of the commercially available
Tetronic.TM. compounds, marketed by BASF.
Nonionic alkylpolysaccharide surfactant
Suitable alkylpolysaccharides for use herein are disclosed in U.S. Pat. No.
4,565,647, Llenado, issued Jan. 21, 1986, having a hydrophobic group
containing from about 6 to about 30 carbon atoms, preferably from about 10
to about 16 carbon atoms and a polysaccharide, e.g., a polyglycoside,
hydrophilic group containng from about 1.3 to about 10, preferably from
about 1.3 to about 3, most preferably from about 1.3 to about 2.7
saccharide units. Any reducing saccharide containing 5 or 6 carbon atoms
can be used, e.g., glucose, galactose and galactosyl moieties can be
substituted for the glucosyl moieties. (Optionally the hydrophobic group
is attached at the 2-, 3-, 4-, etc. positions thus giving a glucose or
galactose as opposed to a glucoside or galactoside.) The intersaccharide
bonds can be, e.g., between the one position of the additional saccharide
units and the 2-, 3-, 4-, and/or 6- positions on the preceding saccharide
units.
The preferred alkylpolyglycosides have the formula
R.sub.2 O(C.sub.n H.sub.2n O)t(glycosyl).sub.x
wherein R2 is selected from the group consisting of alkyl, | | |
