Note: Descriptions are shown in the official language in which they were submitted.
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MICROEMULSION LIGHT DUTY LIQUID CLEANING COMPOSITIONS
Field of the Invention
This invention relates to an improved light duty liquid cleaner in the form of a5 microemulsion designed in particular for cleaning hard surfaces and which is effective in
removing grease soil and/or kitchen soil and in leaving unrinsed surfaces with a shiny
appearance.
R~k~round of the Invention
In recent years liquid detergents have become widely accepted for cleaning hard
10 surfaces, e.g., painted woodwork and panels, tiled walls, wash bowls, bathtubs,
linoleum or tile floors, washable wall paper, etc.. Such liquids comprise clear and
opaque aqueous mixtures of water-soluble synthetic organic detergents and water-soluble detergent builder salts. In order to achieve comparable cleaning efficiency with
granular or powdered all-purpose cleaning compositions, use of water-soluble inorganic
15 phosphate builder salts was favored in the prior art all-purpose liquids. For example,
such early phosphate-containing compositions are described in U.S. Patent Nos.
2,560,839; 3,234,138; 3,350,319; and British Patent No. 1,223,739.
In view of the environmentalist's efforts to reduce phosphate levels in ground
water, improved all-purpose liquids containing reduced concentrations of inorganic
20 phosphate builder salts or non-phosphate builder salts have appeared. A particularly
useful self-opacified liquid of the latter type is described in U.S. Patent No. 4,244,840.
However, these prior art liquid detergents containing detergent builder salts orother equivalent tend to leave films, spots or streaks on cleaned unrinsed surfaces,
particularly shiny surfaces. Thus, such liquids require thorough rinsing of the cleaned
25 surfaces which is a time-consuming chore for the user.
In order to overcome the foregoing disadvantage of the prior art, U.S. Patent No.
4,017,409 teaches that a mixture of paraffin sulfonate and a reduced concentration of
inorganic phosphate builder salt should be employed. However, such compositions are
not completely acceptable from an environmental point of view based upon the
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phosphate content. On the other hand, another alternative to achieving phosphate-free
all-purpose liquids has been to use a major proportion of a mixture of anionic and
nonionic detergents with minor amounts of glycol ether solvent and organic amine as
shown in U.S. Patent No. 3,935,130. Again, this approach has not been completelysatisfactory and the high levels of organic detergents necessary to achieve cleaning
cause foaming which, in turn, leads to the need for thorough rinsing which has been
found to be undesirable to today's consumers.
Another approach to formulating hard surfaced liquid detergent composition
where product homogeneity and clarity are important considerations involves the
formation of oil-in-water (o/w) microemulsions which contain one or more surface-active
detergent compounds, a water-immiscible solvent (typically a hydrocarbon solvent),
water and a "cosurfactant" compound which provides product stability. By definition, an
o/w microemulsion is a spontaneously forming colloidal dispersion of "oil" phaseparticles having a particle size in the range of 25 to 800 A in a continuous aqueous
phase. In view of the extremely fine particle size of the dispersed oil phase particles,
microemulsions are transparent to light and are clear and usually highly stable against
phase separation.
Patent disclosures relating to use of grease-removal solvents in o/w
microemulsions include, for example, European Patent Applications EP 0137615 andEP 0137616 - Herbots et al; European Patent Application EP 0160762 - Johnston et al;
and U.S. Patent No. 4,561,991 - Herbots et al. Each of these patent disclosures also
teaches using at least 5% by weight of grease-removal solvent.
It also is known from British Patent Application GB 2144763A to Herbots et al,
published March 13,1985, that magnesium salts enhance grease-removal performanceof organic grease-removal solvents, such as the terpenes, in o/w microemulsion liquid
detergent compositions. The compositions of this invention described by Herbots et al.
require at least 5% of the mixture of grease-removal solvent and magnesium salt and
preferably at least 5% of solvent (which may be a mixture of water-immiscible non-polar
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solvent with a sparingly soluble slightly polar solvent) and at least 0.1 % magnesium
salt.
However, since the amount of water immiscible and sparingly soluble
components which can be present in an o/w microemulsion, with low total active
5 ingredients without impairing the stability of the microemulsion is rather limited (for
example, up to 18% by weight of the aqueous phase), the presence of such high
quantities of grease-removal solvent tend to reduce the total amount of greasy or oily
soils which can be taken up by and into the microemulsion without causing phase
separation. The following representative prior art patents also relate to liquid detergent
10 cleaning compositions in the form of o/w microemulsions: U.S. Patents Nos4,472,291
- Rosario; 4,540,448 - Gauteer et al; 3,723,330 - Sheflin.
Liquid detergent compositions which include terpenes, such as d-limonene, or
other grease-removal solvent, although not disclosed to be in the form of o/w
microemulsions, are the subject matter of the following representative patent
documents: European Patent Application 0080749; British Patent Specification
1,603,047; 4,414,128; and 4,540,505. For example, U.S. Patent No. 4,414,128 broadly
discloses an aqueous liquid detergent composition characterized by, by weight:
(a) from 1 % to 20% of a synthetic anionic, nonionic, amphoteric or
zwitterionic surfactant or mixture thereof;
(b) from 0.5% to 10% of a mono- or sesquiterpene or mixture thereof, at a
weight ratio of (a):(b) Iying in the range of 5:1 to 1 :3; and
(c ) from 0.5% 10% of a polar solvent having a solubility in water at 15~C. in
the range of from 0.2% to 10%. Other ingredients present in the formulations disclosed
in this patent include from 0.05% to 2% by weight of an alkali metal, ammonium or
alkanolammonium soap of a C13-c24 fatty acid; a calcium sequestrant from .5% to
~ 13% by weight; non-aqueous solvent, e.g., alcohols and glycol ethers, up to 10% by
weight; and hydrotropes, e.g., urea, ethanolamines, salts of lower alkylaryl sulfonates,
up to 10% by weight. All of the formulations shown in the Examples of this patent
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include relatively large amounts of detergent builder salts which are detrimental to
surface shine.
Furthermore, the present inventors have observed that in formulations containinggrease-removal assisting magnesium compounds, the addition of minor amounts of
5 builder salts, such as alkali metal polyphosphates, alkali metal carbonates,
nitrilotriacetic acid salts, and so on, tends to make it more difficult to form stable
microemulsion systems.
Summary of the Invention
The present invention provides an improved, clear light duty liquid cleaning
10 composition having improved interfacial tension which improves cleaning in the form of
a microemulsion which is suitable for cleaning hard surfaces such as dishes, plastic,
vitreous and metal surfaces having a shiny finish. The light duty liquid microemulsion
compositions of the instant invention can be generally described as comprising
approximately by weight:
(a) 10 % to 34% of a mixture of a alkali metal salt of a C13-C17 secondary
alkane sulfonate surfactant and an alkali metal salt of a Cg-C1g alkyl polyethenoxy
sulfate surfactant, wherein the ratio of sulfonate surfactant to the sulfate surfactant is
1.2.:1 to 14:1, more preferably 1.35:1 to 5:1
(b) 1 to 25 % of a modified alkyl polyglucoside surfactant or an alkyl ethoxy
citrate such as lauryl ethoxy citrate;
(c) 0.4% to 10.0%, more preferably 1.0% to 8.0% of a perfume, an essential
oil or a water insoluble hydrocarbon;
(d) 0 to 25% of a cosurfactant, more preferably 2 to 15% of a cosurfactant;
(e) 0 to 25% of a zwitterionic surfactant such as a betaine; and
(f) the balance being water, wherein the composition has a Brookfield
viscosity at 25~C at 30 rpms using a #2 spindle of 20 to 500 cps, more preferably 200
to 450 cps, a pH of 5 to 7, and a light transmission of at least 95%, more preferably at
98%.
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net~ile~ I )escri~tion of the Invention
The present invention relates to a stable microemulsion composition
approximately by weight: 1% to 25 % of a modified polyglucoside surfactant or an alkyl
ethoxy citrate, 10 % to 34% of a mixture of secondary alkane sulfonate anionic
5 surfactant and an alkyl ether polyethenoxysulfate surfactant. 0% to 25% of a
cosurfactant, 0 to 25 % of a zwitterionic surfactant such as betaine, 0.4% to 10% of a
water insoluble hydrocarbon essential oil or a perfume and the balance being water,
said composition having a light trans")ission of at least 95%, more preferably at least
98%.
According to the present invention, the role of the hydrocarbon is provided by anon-water-soluble perfume. Typically, in aqueous based compositions the presence of
a solubilizers, such as alkali metal lower alkyl aryl sulfonate hydlolrope,
triethanolamine, urea, etc., is required for perfume dissolution, especially at perfume
levels of 1% and higher, since perfumes are generally a mixture of fragrant essential
15 oils and aromatic compounds which are generally not water-soluble. Therefore, by
incorporating the perfume into the aqueous cleaning composition as the oil
(hydrocarbon) phase of the ultimate o/w microemulsion composition, several different
important advantages are achieved.
First, the cosmetic properties of the ultimate cleaning composition are improved:
20 the compositions are both clear (as a consequence of the formation of a microemulsion)
and highly fragranced (as a consequence of the perfume level).
Second, the need for use of solubilizers, which do not co"l~ibute to cleaning
performance, is eliminated.
As used herein and in the appended claims the term "perfume" is used in its
25 ordinary sense to refer to and include any non-water soluble fragrant substance or
mixture of suhst~nces including natural (i.e., obtained by extraction of flower, herb,
blossom or plant), artificial (i.e., mixture of natural oils or oil constituents) and
synthetically produced subst?~nce) odoriferous sl~hst~nces. Typically, perfumes are
complex mixtures of blends of various organic compounds such as alcohols, aldehydes,
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ethers, aromatic compounds and varying amounts of essential oils (e.g., terpenes) such
as from 0% to 80%, usually from 10% to 70% by weight, the essential oils themselves
being volatile odoriferous compounds and also serving to dissolve the other
components of the perfume.
In the present invention the precise composition of the perfume is of no particular
consequence to cleaning pertormance so long as it meets the criteria of water
immiscibility and having a pleasing odor. Naturally, of course, especially for cleaning
compositions intended for use in the home, the perfume, as well as all other
ingredients, should be cosmetically acceptable, i.e., non-toxic, hypoallergenic, etc.
The hydrocarbon such as a perfume is present in the dilute o/w microemulsion in
an amount of from 0.4% to 10% by weight, preferably from 1.0% to 8% by weight,
especially preferably from 2% to 7% by weight. If the amount of hydrocarbon (perfume)
is less than 0.4% by weight it becomes difficult to form the o/w microemulsion. If the
hydrocarbon (perfume) is added in amounts more than 10% by weight, the cost is
15 increased without any additional cleaning benefit and, in fact, with some diminishing of
cleaning performance insofar as the total amount of greasy or oily soil which can be
taken up in the oil phase of the microemulsion will decrease proportionately.
Furthermore, although superior grease removal performance will be achieved for
perfume compositions not containing any terpene solvents, it is apparently difficult for
20 perfumers to formulate sufficiently inexpensive pertume compositions for products of
this type (i.e., very cost sensitive consumer-type products) which includes less than
20%, usually less than 30%, of such terpene solvents.
Thus, merely as a practical matter, based on economic consideration, the dilute
o/w microemulsion detergent cleaning compositions of the present invention may often
25 include as much as 0.2% to 7% by weight, based on the total composition, of terpene
solvents introduced thereunto via the pertume component. However, even when the
amount ot terpene solvent in the cleaning formulation is less than 1.5% by weight, such
as up to 0.6% by weight or 0.4% by weight or less, satisfactory grease removal and oil
removal capacity is provided by the inventive diluted o/w microemulsions.
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In place of the perfume one can employ an essential oil such as D-limonene or
alpha-terpineol, a water insoluble paraffin or isoparaffin having 6 to 18 carbon at a
' concentration of 0.4 to 10 wt. percent, more preferably 0.4 to 8.0 wt. %.
Suitable essential oils are selected from the group consisting of:
Anethole 20/21 natural, Aniseed oil china star, Aniseed oil globe brand, Balsam (Peru),
Basil oil (India), Black pepper oil, Black pepper oleoresin 40/20, Bois de Rose (Brazil)
FOB, Borneol Flakes (China), Camphor oil, White, Camphor powder synthetic technical,
Cananga oil (Java), Cardamom oil, Cassia oil (China), Cedarwood oil (China) BP,
Cinnamon bark oil, Cinnamon leaf oil, Citronella oil, Clove bud oil, Clove leaf, Coriander
(Russia), Coumarin 69~C (China), Cyclamen Aldehyde, Diphenyl oxide, Ethyl vanilin,
Eucalyptol, Eucalyptus oil, Eucalyptus citriodora, Fennel oil, Geranium oil, Ginger oil,
Ginger oleoresin (India), White grapefruit oil, Guaiacwood oil, Gurjun balsam,
Heliotropin, Isobornyl acetate, Isolongifolene, Juniper berry oil, L-methyl acetate,
Lavender oil, Lemon oil, Lemongrass oil, Lime oil distilled, Litsea Cubeba oil,
Longifolene, Menthol crystals, Methyl cedryl ketone, Methyl chavicol, Methyl salicylate,
Musk ambrette, Musk ketone, Musk xylol, Nutmeg oil, Orange oil, Patchouli oil,
Peppermint oil, Phenyl ethyl alcohol, Pimento berry oil, Pimento leaf oil, Rosalin,
Sandalwood oil, Sandenol, Sage oil, Clary sage, Sassafras oil, Spearmint oil, Spike
lavender, Tagetes, Tea tree oil, Vanilin, Vetyver oil (Java), Wintergreen.
Suitable water-soluble non-soap, anionic detergents include those surface-activeor detergent compounds which contain an organic hydrophobic group containing
generally 8 to 26 carbon atoms and preferably 10 to 18 carbon atoms in their molecular
structure and at least one water-solubilizing group selected from the group of sulfonate,
sulfate and carboxylate so as to form a water-soluble detergent. Usually, the
hydrophobic group will include or comprise a Cg-C22 alkyl, alkylaryl or acyl group.
~ Such detergents are employed in the form of water-soluble salts and the salt-forming
cation usually is selected from the group consisting of sodium, potassium, ammonium,
magnesium and mono-, di- or tri-C2-C3 alkanolammonium, with the sodium,
magnesium and ammonium cations again being preferred.
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Examples of suitable sulfonated anionic detergents are the well known higher
alkyl mononuclear aromatic sulfonates such as the higher alkyl benzene sulfonates
containing from 10 to 16 carbon atoms in the higher alkyl group in a straight orbranched chain, Cg-C1s alkyl toluene sulfonates and Cg-C1s alkyl phenol sulfonates.
A preferred sulfonate is linear alkyl benzene sulfonate having a high content of 3-
(or higher) phenyl isomers and a correspondingly low content (well below 50%) of 2- (or
lower) phenyl isomers, that is, wherein the benzene ring is preferably attached in large
part at the 3 or higher (for example, 4, 5,6 or 7) position of the alkyl group and the
content of the isomers in which the benzene ring is attached in the 2 or 1 position is
correspondingly low. Particularly preferred materials are set forth in U.S. Patent
3,320,174.
Other suitable anionic detergents are the olefin sulfonates, including long-chain
alkene sulfonates, long-chain hydroxyalkane sulfonates or mixtures of alkene
sulfonates and hydroxyalkane sulfonates. These olefin sulfonate detergents may be
prepared in a known manner by the reaction of sulfur trioxide (SO3) with long-chain
olefins containing 8 to 25, preferably 12 to 21 carbon atoms and having the formula
RCH=CHR1 where R is a higher alkyl group of 6 to 23 carbons and R1 is an alkyl group
of 1 to 17 carbons or hydrogen to form a mixture of sultones and alkene sulfonic acids
which is then treated to convert the sultones to sulfonates. Preferred olefin sulfonates
contain from 14 to 16 carbon atoms in the R alkyl group and are obtained by sulfonating
an 2 olefin.
Other examples of suitable anionic sulfonate surfactants are the paraffin
sulfonates containing 10 to 20, preferably 13 to 17, carbon atoms. Primary paraffin
sulfonates are made by reacting long-chain alpha olefins and bisulfites and paraffin
sulfonates having the sulfonate group distributed along the paraffin chain are shown in
U.S. Patents Nos.. 2,503,280; 2,507,088; 3,260,744; 3,372,188; and German Patent735,096. The preferred anionic sulfonate surfactants used in the instant compositions
are the C13-C17 secondary alkane sulfonate surfactants.
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Examples of s~tisf~tory anionic sulfate detergents are the Cg-C18 alkyl sulfate
salts and the Cg-C18 alkyl ether polyethenoxy sulfate salts having the formula
R(OC2H4)n OSO3M wherein n is 1 to 12, preferably 1 to 5, and M is a solubilizingcation selected from the group consisting of sodium, potassium, ammonium,
magnesium and mono-, di- and triethanol ammonium ions. The alkyl sulfates may beobtained by sulfating the alcohols obtained by reducing glycerides of coconut oil or
tallow or mixtures thereof and neutralizing the resultant product. On the other hand, the
alkyl ether polyethenoxy sulfates are obtained by sulfating the condensation product of
ethylene oxide with a Cg-C1g alkanol and neutralizing the resultant product. The alkyl
sulfates may be obtained by sulfating the alcohols obtained by reducing glycerides of
coconut oil or tallow or mixtures thereof and neutralizing the resultant product. On the
other hand, the alkyl ether polyethenoxy sulfates are obtained by sulfating the
condensation product of ethylene oxide with a Cg-C1g alkanol and neutralizing the
resultant product. The alkyl ether polyethenoxy sulfates differ from one another in the
number of moles of ethylene oxide reacted with one mole of alkanol. Preferred alkyl
sulfates and preferred alkyl ether polyethenoxy sulfates contain 10 to 16 carbon atoms
in the alkyl group.
The Cg-C12 alkylphenyl ether polyethenoxy sulfates containing from 2 to 6
moles of ethylene oxide in the molecule also are suitable for use in the inventive
compositions. These detergents can be prepared by reacting an alkyl phenol with 2 to
6 moles of ethylene oxide and sulfating and neutralizing the resultant ethoxylated
alkylphenol.
Other suitable anionic detergents are the Cg-C1 5 alkyl ether polyethenoxyl
carboxylates having the structural formula R-0(C2H40)nR1 COOX wherein n is a
number from 4 to 12, preferably 5 to 10 R1 is selected from the group consisting of
CH2 TO C3H6 and X= H+, Na+, K+, Li+, NH4+, DEA, TEA or other cations including
multivalent.R is a fatty group from C8 to C18-
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10 : .' ;':''"
Obviously these anionic detergents will be present either in acid form or salt form
depending upon the pH of the final composition, with salt forming cation being the same
as for the other anionic detergents.
Of the foregoing non-soap anionic detergents, the preferred detergents are the
Cg-C15 linear alkylbenzene sulfonates and the C1 3-C17 paraffin or secondary alkane
sulfonates. Particularly, preferred compounds are sodium Cl o-Cl 3 alkylbenzene
sulfonate and sodium Cl 3-C17 secondary alkane sulfonate. Generally, the proportion
of the nonsoap-anionic sulfonate detergent will be in the range of 1.0% to 25 %,preferably from 1% to 7%, by weight of the dilute o/w microemulsion composition.Generally, the proportion of the nonsoap-anionic alkyl ether polyethonoxy sulfate
detergent will be in the range of 1% to 20 %, preferably from 2% to 10%, by weight of
the di!ute o/w microemulsion composition, wherein the ratio of anionic sulfonate to the
alkyl ether polyethenoxy sulfate is 1.2:1 to 14:1, more preferably 1.3:1 to 5:1.The water-soluble zwitterionic surfactant, which is also an essential ingredient of
15 present liquid detergent composition, constitutes 0 to 25 %, preferably 1% to 10%, by
weight and provides good foaming properties and mildness to the present nonionicbased liquid detergent. The zwitterionic surfactant is a water soluble betaine having the
general formula:
.. R2
1 +
R1 ~R4 X
R3
wherein X~ is selected from the group consisting of CO2- and SO3- and R1 is an alkyl
25 group having 10 to 20 carbon atoms, preferably 12 to 16 carbon atoms, or the amido
radical
R~CO--N H~C H2)~
wherein R is an alkyl group having 9 to 19 carbon atoms and a is the integer 1 to 4; R2
and R3 are each alkyl groups having 1 to 3 carbons and preferably 1 carbon; R4 is an
30 alkylene or hydroxyalkylene group having from 1 to 4 ca!bon atoms and, optionally, one -
~,4EN0ED SHEFr
CA 0220~8~4 1997-0~-22
hydroxyl group. Typical alkyldimethyl betaines include decyl dimethyl betaine or 2-(N-
decyl-N, N-dimsthyl-ammonia) acetate, coco dimethyl betaine or 2-(1~!-coco N, N-dimethylammonio) acetate, myristyl dimethyl betaine, palmityl dimethyl betaine, lauryl
dimethyl betaine, cetyl dimethyl betaine, stearyl dimethyl betaine, etc. The
amidobetaines similarly include cocoamidoethylbetaine, cocoamidopropyl betaine and
the like. A preferred betaine is coco (Cg-Clg) amidopropyl dimethyl betaine.
One of the biodegradable anionic surfactants useful in the instant invention is a
sodium salt of a di-alcohol ethoxy citrate which is depicted by the formula:
R~CH2~H2--~OC~H2
X+ OO~OH
~O~CH2--CH2--0)~0~CH2
wherein R is an alkyl group of 10 to 16 carbon atoms. An especially preferred
15 biodegradable anionic surfactant is a di-laureth citrate, sodium salt manufactured by
Auschem wherein X+ is selected from the group consisting of sodiu, potassium,
ammonium, triethanol amine diethanol amine and mdnoethanol amine, wherein sodiumis preferred and m and n are each a number from 1 to 12, more preferably 5 to 9, most
preferably 7.
Another biodegradable anionic surfactant is a modified alkyl polyglycoside
depicted by the formula
f;H2 ~~
/o
n o < Jo~b
OH
_ m
R=ALCOOL GRAS (radical)
AMENDED SHEET
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wherein R is a C1 o to C16 alkyl group,m is a number average which is less than 4 and
is of such a value to provide a number molecular weight of 500 to 1000, preferably 1 to
4, and X is selected from the group consisting of
5 COCH2~HCOOZ (sold under the tradename of Eucaroltm APG/SS),
o3z
COCH2~0H - CH200Z (sold under the tradename of Eucaroltm APG/EC)
~OOZ
and CO - ~OH - CH - COOZ (sold under the tradename of Eucaroltm APG/ET )
~H
wherein Z is selected from the group consisting of sodium, potassium, ammonium,
triethanol amine, diethanol amine and monoethanol amine.
15 Euacarol is a trade name of Auschem
The cosurfactant may play an essential role in the formation of the
microemulsion compositions. Very briefly, in the absence of the cosurfactant the water,
detergent(s) and hydrocarbon (e.g., perfume) will, when mixed in appropriate
proportions form either a micellar solution (low concentration) or form an oil-in-water
20 emulsion in the first aspect of the invention. With the cosurfactant added to this system,
the interfacial tension at the interface between the emulsion droplets and aqueous
phase is reduced to a very low value (never negative). This reduction of the interfacial
tension results in spontaneous break-up of the emulsion droplets to consecutively
smaller aggregates until the state of a transparent colloidal sized emulsion. e.g., a
25 microemulsion, is formed. In the state of a microemulsion, thermodynamic factors
come into balance with varying degrees of stability related to the total free energy of the
microemulsion. Some of the thermodynamic factors involved in determining the total
free energy of the system are (1 ) particle-particle potential; (2) interfacial tension or free
energy (stretching and bending); (3) droplet dispersion entropy; and (4) chemical
30 potential changes upon formation. A thermodynamically stable system is achieved
AMENOE~ SHEEI
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13
when (2) interfacial tension or free energy is minimized and (3) droplet dispersion
entropy is maximized. Thus, the role of cosurfactant in formation of a stable o/w
microemulsion is to (a) decrease interfacial tension (2); and (b) modify the
microemulsion structure and increase the number of possible configurations (3). Also,
5 the cosurfactant will (c) decrease the figidity.
Generally, an increase in cosurfactant concentration results in a wider
temperature range of the stability of the product.
The major class of compounds found to provide highly suitable cosurfactants for
the microemulsion over temperature ranges extending from 5~C to 43~C for instance
10 are glycerol, ethylene glycol, water-soluble polyethylene glycols having a molecular
weight of 300 to 1000, polypropylene glycol of the formula HO(CH3CHCH2O)nH
wherein n is a number from 2 to 18, mixtures of polyethylene glycol and polypropyl
glycol (Synalox) and mono C1-C6 alkyl ethers and esters of ethylene glycol and
propylene glycol having the structural formulas R(X)nOH and R1 (X)nOH wherein R is
15 C1-C6 alkyl group, R1 is C2-C4 acyl group, X is (OCH2CH2) or (OCH2(CH3)CH) and n
is a number from 1 to 4, diethylene glycol, triethylene glycol, an alkyl lactate, wherein
the alkyl group has 1 to 6 carbon atoms, 1 methoxy-2-propanol, 1 methoxy-3-propanol,
and 1 methoxy 2-, 3- or 4-butanol.
Representative members of the polypropylene glycol include dipropylene glycol
20 and polypropylene glycol having a molecular weight of 200 to 1000, e.g., polypropylene
glycol 400. Other satisfactory glycol ethers are ethylene glycol monobutyl ether (butyl
cellosolve), diethylene glycol monobutyl ether (butyl carbitol), triethylene glycol
monobutyl ether, mono, di, tri propylene glycol monobutyl ether, tetraethylene glycol
monobutyl ether, mono, di, tripropylene glycol monomethyl ether, propylene glycol
25 monomethyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether,
- propylene glycol tertiary butyl ether, ethylene glycol monoethyl ether, ethylene glycol
monomethyl ether, ethylene glycol monopropyl ether, ethylene glycol monopentyl ether,
diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene
glycol monopropyl ether, diethylene glycol monopentyl ether, triethylene glycol
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14
monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl
ether, triethylene glycol monopentyl ether, triethylene glycol monohexyl ether, mono, di,
tripropylene glycol monoethyl ether, mono, di tripropylene glycol monopropyl ether,
mono, di, tripropylene glycol monopentyl ether, mono, di, tripropylene glycol monohexyl
5 ether, mono, di, tributylene glycol mono methyl ether, mono, di, tributylene glycol
monoethyl ether, mono, di, tributylene glycol monopropyl ether, mono, di, tributylene
glycol monobutyl ether, mono, di, tributylene glycol monopentyl ether and mono, di,
tributylene glycol monohexyl ether, ethylene glycol monoacetate and dipropylene glycol
propionate. When these glycol type cosurfactants are at a concentartion of 1.0 to 14
10 weight %, more preferably 2.0 weight % to 10 weight % in combination with a water
insoluble hydrocarbon at a concentration of at least 0.5 weight %, more preferably 1.5
weight % one can form a microemulsion composition.
While all of the aforementioned glycol ether compounds provide the described
stability, the most preferred cosurfactant compounds of each type, on the basis of cost
15 and cosmetic appearance (particularly odor), are glycerol, dipropylene glycolmonomethyl ether and propylene glycol. Less preferred cosurfactants are ethanol,propanol isopropanol, butanol, isobutanol and alkanols having 5 to 7 carbon atoms.
The amount of cosurfactant required to stabilize the microemulsion compositions
will, of course, depend on such factors as the surface tension characteristics of the
20 cosurfactant, the type and amounts of the primary surfactants and perfumes, and the
type and amounts of any other additional ingredients which may be present in thecomposition and which have an influence on the thermodynamic factors enumerated
above. Generally, amounts of cosurfactant in the range of from 0% to 25%, preferably
from 0.5% to 15%, especially preferably from 2% to 13%, by weight provide stable25 dilute o/w microemulsions for the above-described levels of primary surfactants and
perfume and any other additional ingredients as described below.
The final essential ingredient in the inventive light duty liquid microemulsion
compositions having improved interfacial tension properties is water. The proportion of
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WO 96116160 PCI/US9S/lSS22
water in the microemulsion compositions generally is in the range of 20% to 97%,preferably 70% to 97% by weight of the usual diluted o/w microemulsion composition.
As believed to have been made clear from the foregoing description, the light
duty liquid microemulsion compositions of this invention are especially effective when
5 used as is, that is, without further dilution in water, since the properties of the
composition as a microemulsion are best manifested in the neat (undiluted) form.However, at the same time it should be understood that depending on the levels of
surfactants, cosurfactants, perfume and other ingredients, some degree of dilution
without disrupting the microemulsion, per se, is possible. For example, at the preferred
10 low levels of active surfactant compounds dilutions up to 50% will generally be well
tolerated without causing phase separation, that is, the microemulsion state will be
maintained.
However, even when diluted to a great extent, such as a 2- to 1 0-fold or more
dilution, for example, the resulting compositions are still effective in cleaning greasy,
15 oily and other types of soil. Furthermore, the presence of magnesium ions or other
polyvalent ions, e.g., aluminum, as will be described in greater detail below further
serves to boost cleaning performance of the primary detergents in dilute usage.
In addition to the above-described essential ingredients required for the
formation of the microemulsion composition, the compositions of this invention may
20 possibly contain one or more additional ingredients which serve to improve overall
product performance.
One such ingredient is an inorganic or organic salt of oxide of a multivalent metal
cation, particularly Mg++. The metal salt or oxide provides several benefits including
improved cleaning performance in dilute usage, particularly in soft water areas, and
25 minimized amounts of perfume required to obtain the microemulsion state. Magnesium
- sulfate, either anhydrous or hydrated (e.g., heptahydrate), is especially preferred as the
magnesium salt. Good results also have been obtained with magnesium oxide,
magnesium chloride, magnesium acetate, magnesium propionate and magnesium
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16
hydroxide. These magnesium salts can be used with formulations at neutral or acidic
pH since magnesium hydroxide will not preci,ci~ale at these pH levels.
Although magnesium is the preferred multivalent metal from which the salts
(inclusive of the oxide and hydroxide) are formed, other polyvalent metal ions also can
5 be used provided that their salts are nontoxic and are soluble in the aqueous phase of
the system at the desired pH level. Thus, depending on such factors as the the nature
of the primary surfactants and cosurfactant, and so on, as well as the availability and
cost factors, other suitable polyvalent metal ions include aluminum, copper, nickel, iron,
calcium, etc. can be employed. It should be noted, for example, that with the preferred
10 paraffin sulfonate anionic detergent calcium salts will preci,c i~ale and should not be
used. It has also been found that the aluminum salts work best at pH below 5 or when
a low level, for example 1 weight percent, of citric acid is added to the composition
which is designed to have a neutral pH. Alternatively, the aluminum salt can be directly
added as the citrate in such case. As the salt, the same general classes of anions as
15 mentioned for the magnesium salts can be used, such as halide (e.g., bromide,chloride), sulfate, nitrate, hydroxide, oxide, acetate, propionate, etc.
Preferably, in the dilute compositions the metal compound is added to the
composition in an amount sufficient to provide at least a stoichiometric equivalent
between the anionic surfactant and the multivalent metal cation. For example, for each
20 gram-ion of Mg++ there will be 2 gram moles of paraffin sulfonate, alkylbenzene
sulfonate, etc., while for each gram-ion of A13+ there will be 3 gram moles of anionic
surfactant. Thus, the proportion of the multivalent salt generally will be selected so that
one equivalent of compound will neutralize from 0.1 to 1.5 equivalents, preferably 0.9 to
1.4 equivalents, of the acid form of the anionic detergent. At higher concentrations of
25 anionic detergent, the amount of multivalent salt will be in range of 0.5 to 1 equivalents
per equivalent of anionic detergent. The concentration of the magnesium sulfate is 0 to
4%, more ,~,referably 0.1 to 2% by weight.
The light duty liquid microemulsion composition of this invention may, if desired,
also contain other components either to provide additional effect or to make the product
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more attractive to the consumer. The following are mentioned by way of example:
Colors or dyes in amounts up to 0.5% by weight; bactericides in amounts up to 1% by
weight; preservatives or antioxidizing agents, such as formalin, 5-chloro-2-methyl-4-
isothaliazolin-3-one, 2,6-di-tert.butyl-p-cresol, etc., in amounts up to 2% by weight; and
5 pH adjusting agents, such as sulfuric acid or sodium hydroxide, as needed.
Because the compositions as prepared are aqueous liquid formulations and
since no particular mixing is required to form the o/w microemulsion, the compositions
are easily prepared simply by combining all the ingredients in a suitable vessel or
container. The order of mixing the ingredients is not particularly important and10 generally the various ingredients can be added sequentially or all at once or in the form
of aqueous solutions of each or all of the primary detergents and cosurfactants can be
separately prepared and combined with each other and with the perfume. The
magnesium salt, or other multivalent metal compound, when present, can be added as
an aqueous solution thereof or can be added directly. It is not necessary to use15 elevated temperatures in the formation step and room temperature is sufficient.
The following examples illustrate liquid cleaning compositions of the described
invention. Unless otherwise specified, all percentages are by weight. The exemplified
compositions are illustrative only and do not limit the scope of the invention. Unless
otherwise specified, the proportions in the examples and elsewhere in the specification
20 are by weight.
~,~
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18
F~ le 1
The following compositions in wt. % were prepared:
A B C D E F G H I J K
SodiumC13-C17secondary 7.5 11 17.6 7.5 20.112.5 18.9 9.9 21.4
alkane suHonate
Sodium C12-C14alkyl 2.5 1.25 2.5 11.3 5.9 2.5 6.7 4.2 6.3 3.3 7.1
poly~O: ,eno<y ether suHate (2EO)
Biodet Type D 3 10.5 4.513.5 1.5
Eucarol APG/ET (Taltaric ester
of APG)
Eucarol APG/EC (chric ester of
APG)
Eucarol APG/SS (s~'h~:crinate 19.510.5 10.510.5 4.5 16.5
of ~'G)
B~t line 12.2 2.25
~- monene 6 6 6 6 6 6 6 6 6
- erpineol 6 6
Iu~,Jlene glycol 5 10
alycerol 5 5
Di, u~ lle,ne mono methyl ether :: 10
Lightl,c.ns,,,;ss;un% >98 > 8 > 8 > 8 > >98 >98 >98 > 8 > >98
Brookfield viscosity, 25~C, #2 100 1 0 1 5 1 5 1 75 125 75 1 0 1 100
spindle, 30 rpms
L M N O P Q R S T U V W
Sodium C13-C17 seco,nda~y18.9 15 20.1 20.1 20.1 13.8 8.5 16 12.3
alkane suHonate
Sodium C12-C14alkyl 6.3 5 6.7 6.7 6.7 4.6 3.75 5 7.5 5 17.5 7.5
poly~;:,erioxy ether suHate
(2EO)
Biodet Type D
Eucarol APG/ET (Tartaric 3 7.5 1.5
ester of APG)
Eucarol APG/EC (citric ester 3 1.5
pf APG)
IEucarol APG/SS 9 12 1.5 3 1.5 12
¦(s~ H~ . crinate of APG)
B~taine 16 3.5 4.75
~- imonene 6 6 6 6 6 6 6 6 6 6 6 6
-~ erpineol
Iu~.ylene glycol 10 5
31ycerol 10 10
ri, .o~11e~e mono methyl 10 10 5 5 5 5 5 5
ether
Light ~ ns",;~:-iun % >98 >98 >98 ~98 >98 ~98 >98 >98 >98 >98 >98 >98
B,uol~fielcl viscosity 25~C, #2 100 100 150 100 125 75 100 100 100 100 100 100
spindle, 30 rpms
In summary, the described invention broadly relates to an improvement in a lightduty liquid microemulsion composition containing a mixture of a C1 3-C17 secondary
alkane sulfonate surfactant and an alkyl polyethenoxy ether sulfate surfactant, a
biodegradable anionic surfactant, optionally a betaine surfactant, one o~ the specified
cosurfactants, a hydrocarbon ingredient and water to form a microemulsion light duty
liquid composition.
