Technical Field
[0001] This invention relates to homogeneous enzyme-containing liquid detergent compositions
containing substantial levels of saturated fatty acids. These compositions provide
a series of remarkable stability benefits in respect to both functionality optimization
of the individual ingredients and physical stability of the composition. More particularly,
the compositions of this invention unexpectedly provide the cumulative benefits inherent
to the presence of the detergent enzyme and to the substantial level of the saturated
fatty acid.
[0002] There was a standing prejudice against the effective use of the like compositions,
chiefly because of the contradictory behaviour of calcium in respect to saturated
fatty acids and detergent enzymes.
[0003] It is well-known that enzyme-containing liquid detergent compositions require the
presence of certain minimum levels of calcium as a primary stabilizing agent. This
is especially applicable for proteolytic and amylolytic enzymes.
[0004] The liquid enzymatic detergent compositions of the prior art containing substantial
levels of fatty acids and/or soaps are deficient with respect to important product
characteristics. For example, the minimum level of calciur needed tc provide acceptable
enzymatic stability induces precipitation (in the liquid composition) in presence
of substantial levels of saturated fatty acids and/or soaps. The like shortcomings
can be overcome with the aid of known formulation changes inclusive of lowering the
calcium level or using substantial levels of soluble calcium sequestrants. Both approaches
can not be used in the context of this technology. The elimination or the substantial
reduction of the calcium yields enzyme deactivation and instability upon aging. Wrile
the incorporation of strong sequestrants effectively cures the product instability,
concurrently, it yields a substantial lowering of the enzymatic activity. These formulation
constraints were such that it was not practically possible to simultaneously achieve
product homogeneity, and effective enzyme stability in aqueous saturated fatty acid
containing liquid detergents.
[0005] It was now found that the prior art shortcomings can be circumvented with the aid
of a narrowly defined ternary combination, namely a saturated fatty acid, sub-minimum
levels of enzyme-accessible calcium and a specific short-chain carboxylic acid to
thus formulate substantially builder-free homogeneous enzyme-containing liquid detergents.
Description of the Art
[0006] The formulation of enzymatic aqueous detergent compositions containing substantial
levels of saturated fatty acids/ soaps is very difficult because of processing limitations
and also because of the contradictory conditions under which saturated fatty acids/soaps
and enzymes function in relation to calcium. While numerous attempts have been undertaken
to formulate liquid detergent compositions allowing the simultaneous use of saturated
fatty acids and/or soaps in combination with enzymes, success had not attended these
efforts and no commercially-viable technology had been made available. U.S. Patent
3,676,374, Zaki et al., discloses enzymatic detergent compositions on basis of a mixed
sulfonate/nonionic/ sulfate surfactant system and a proteolytic enzyme. Earth alkali-metal
salts inclusive of calcium chloride, calcium .acetate, magnesium chloride and magnesium
acetate are recor.- mended for stabilizing the enzymatic activity. Concentrated enzyme
containing alkaline liquid detergents are also known from French Patent 2,369,338.
The active system of the 338 composition is comprised of a soap, a major amount of
a nonionic ethoxylate and an anionic detergent. Comparable disclosures are known from
French Patent 2,389,672, namely alkaline liquid detergents containing a major amount
of a scap and relatively low level of other organic surfactants and alkaline buffering
agent. Liquid detergent compositions containing a combination of nonionic ethoxylates,
soaps, amylolytic and/or proteolytic enzymes and alkoxylated alkylamines are also
known from Belgian Patent 857,144.
[0007] Thus while the individual ingredients of the claimed invention are conventional in
liquid detergent technology there was a standing prejudice against using them concurrently;
it was also not known that their combined use would provide significant benefits.
[0008] The present invention relates to novel enzymatic liquid detergent compositions containing
substantial amounts of saturated fatty acids, a short chain carboxylic acid, and having
a neutral pH.
Disclosure cf the Invention
[0009] The homogeneous aqueous detergent compositions of this invention comprise: (a) from
about 20% to about 50% by weight of an organic synthetic surface-active agent; (b)
from about 3% to about 15% by weight of a saturated fatty acid having 10 tc 16 carbon
atoms in the alkyl chain;-(c) from 0.025% to about 1% by weight of an enzyme; (d)
from 0.1% to about 3% by weight of a carboxylic acid having from 1 to 3 carbon atoms;
and (e) less than 2 millimoles of enzyme-accessible calcium per kilo cf the detergent
composition, the pH of the composition measured as is at 20°C, being from about 6.5
to 8.5. In the preferred embodiments of this invention, the saturated fatty acids
have from 12 to 14 carbon atoms in the alkyl chain, the detergent enzymes are represented
by proteases or mixtures of prcteases and amylases, the short chain carboxylic acid
is represented by formic acid, the enzyme-accessible calcium is present in an amount
of from about 0.5 to 1.5 millimoles per kilo of the detergent composition, and the
pH of the composition, as is, is in the range from about 7 to about 7.5. The compositions
of this invention are substantially builder free. While the fatty acids and/or soaps
are not considered as detergent builders/ seouestrants in the context of this invention,
the claimed compositions do not contain more than minor amounts of sequestrants.
Detailed Description of the Invention
Organic synthetic surface-active agents.
[0010] The organic synthetic surface-active agents can be selected from nonionic, anionic,
cationic, zwitterionic, amphoteric, and semi-polar nonionic surfactants and mixtures
thereof. While these surfactant components can be used over a -wide concentration
range, they are normally used in levels ranging from about 20% to about 50%.
Nonionic Surfactants.
[0011] The nonionic surfactants are conventionally produced by condensing ethylene oxide
with a hydrocarbon having a reactive hydrogen atom, e.g., a hydroxyl, carboxyl, amino,
or amido group, in the presence of an acidic or basic catalyst. Nonionic surfactants
have the general formula RA(Ch
2CY
2O)
nH wherein R represents the hydrophobic moiety, A represents the group carrying the
reactive hydrogen atom and n represents the average number of ethylene oxide moieties.
R typically contains from about 8 to 22 carbon atoms, but can also be formed by the
condensation of propylene oxide with a lower molecular weight compound. n usually
varies from about 2 to about 24.
[0012] The hydrophobic moiety of the nonionic compound is preferably a primary or secondary,
straight or branched, aliphatic alcohol having from about 8 to about 24, preferably
from about 12 to about 20 carbon atoms. A more complete disclosure of suitable nonionic
surfactants can be found in U.S. Patent 4,111,855 disclosed hereinbefore and incorporated
herein by reference. Mixtures of nonionic surfactants can be desirable.
Anionic Surfactants.
[0013] Synthetic anionic surfactants can be represented by the general formula R
1SO
3M wherein R
1 represents a hydrocarbon group selected from the group consisting of straight or
branched alkyl radicals containing from about 8 to about 24 carbon atoms and alkyl
phenyl radicals containing from about 9 to about 15 carbon atoms in the alkyl group.
M is a salt forming cation which typically is selected from the group consisting of
sodium, potassium, ammonium, menoalkanolammonium dialkanolammonium, trialkanolammonium
and mixtures thereof.
[0014] A preferred synthetic anionic surfactant is a water-soluble salt of an alkylbenzene
sulfonic acid containing from about 9 to about 15 carbon atoms in the alkyl group.
Another preferred synthetic anionic surfactant is a water-soluble salt of an alkyl
polyethoxylate ether sulfate wherein the alkyl group contains from about 8 to about
24, preferably from about 10 to about 18 carbon atoms and there are fron about 1 to
about 20, preferably from about 1 to about 12 ethoxy groups. Other suitable anionic
surfactants are disclosed in U.S. Patent 4,170,565, Flesher et al., issued October
9, 1979, incorporated herein by reference.
Cationic Surfactants.
[0015] Suitable cationic surfactants have the general formula
Y
LZ wherein R
2 is an organic group containing a straight or branched alkyl or alkenyl group optionally
substituted with up to three phenyl or hydroxy groups and optionally interruped by
up to four structures selected from the group consisting of
and mixtures thereof, each R
2containing from about 8 to 22 carbon atoms, and which may additionally contain up
to about
12 ethylene oxide groups, m is a number from 1 to 3, each
R3 is an alkyl or hydroxyalkyl group containing from 1 to 4 carbon atoms or a benzyl
group with no more than one R
3 in a molecule being benzyl, x is a number from 0 to 11, the remainder of any carbon
atom positions being filled by hydrogens, Y is selected from the group consisting
of:
wherein
p is from 1 to 12,
wherein p is from 1 to 12,
and
(9) mixtures thereof.
[0016] A more complete disclosure can be found in U.S. Patent Application Serial Number
No. 919,340, by Cushman M. Cambre for Laundry Detergent Composition Having Enhanced
Particulate Soil Removal and Antiredeposition Performance, filed June 26, 1978, said
application being incorporated herein by reference. Care should be taken in including
cationic materials, including surfactants since some cationic materials have been
found to decrease enzyme effectiveness.
Zwitterionic Surfactants.
[0017] Zwitterionic surfactants include derivatives of aliphatic quaternary ammonium, phosphonium,
and sulphonium compounds in which the aliphatic moiety can be straight or branched
chain and wherein one of the aliphatic substituents contains from about 8 to about
24 carbon atoms and one contains an anionic water-solubilizing group. Particularly
preferred zwitterionic materials are the ethoxylated ammonium sulfonates and sulfates
disclosed in U.S. Patents 3,925,262, Laughlin et al., issued December 9, 1975 and
3,929,678, Laughlin et al., issued December 30, 1975, said patents being incorporated
herein by reference.
Ampholytic Surfactants.
[0018] Ampholytic surfactants include derivatives of aliphatic heterocyclic secondary and
ternary amines in which the aliphatic moiety can be straight chain or branched and
wherein one of the aliphatic substituents contains from about 8 to about 2% carbon
atoms and at least one aliphatic susbtituent contains an anionic water-solubilizing
group.
Semi-Polar Nonionic Surfactants.
[0019] Semi-polar nonionic surfactants include water-soluble amine oxides containing one
alkyl or hydroxy alkyl moiety of from about 8 to about 28 carbon atoms and two moieties
selected from the group consisting of alkyl groups and hydroxy alkyl groups, containing
from 1 to about 3 carbon atoms which can optionally be joined into ring structures;
water-soluble phosphine oxides containing one alkyl or hydroxy alkyl moiety of from
about 8 to about 28 and two moieties selected from the group consisting of alkyl groups
and hydroxy alkyl groups, containing from about 1 to about 3 carbon atoms and water-soluble
sulfoxides containing one alkyl or hydroxy alkyl moiety of from about 8 to about 28
carbon atoms and a moiety selected from the group consisting of alkyl and hdryoxy
alkyl moieties of from 1 to 3 carbon atoms.
[0020] For a more complete disclosure of compounds which are suitable for incorporation
in detergent compositions, one can consult U.S. Patents 4,056,481, Tate (November
1, 1977); 4,049,586, Collier (September 20, 1977); 4,040,988, Vincent et al. (August
9, 1977); 4,035,257, Cherney (July 12, 1977); 4,4033,716, Holcolm et al. (July 5,
1977); 4,019,999, Ohren et al. (April 26, 1977): 4,019,998, Vincent et al. (April
26, 1977); and 3,985,669, Krummel et al. (October 12, 1976); all of said patents being
incorporated herein by reference.
[0021] Preferred in the compositions of this invention is a binary active system consisting
essentially of: an anionic synthetic surface-active salt selected from the group of
sulfonates and sulfates and an ethoxylated nonionic surface-active agent, whereby
the weight ratio of the anionic surface-active salt to the nonionic ethoxylate is
generally in the range from 4:1 to 1:4 and more preferably in the range from 5:2 to
3:4.
[0022] Suitable anionic synthetic surface-active salts are selected from the group of sulfonates
and sulfates. The like anionic detergents are eminently well-known in the detergent
arts and have found wide-spread application in commercial detergents. Preferred anionic
synthetic water-soluble sulfonate or sulfate salts have in their molecular structure
an alkyl radical containing from about 8 to about 22 carbon atoms. Examples of such
preferred anionic surfactant salts are the reaction products obtained by sulfating
C
8-C
18 fatty alcohols derived from tallow and coconut oil; alkylbenzene sulfonates wherein
the alkyl group contains from about 8 to 15 carbon atoms; sodium alkylglyceryl ether
sulfonates: ether sulfates of fatty alcohols derived from tallow and coconut oils;
coconut fatty acid monoglycerid sulfates and sulfonates; and water-soluble salts of
paraffin sulfonates having from about 8 to about 22 carbon atoms in the alkyl chain.
Sulfonated olefin surfactants as more fully described in e.g. U.S. Patent Specification
3,332,E80, incorporated herein by reference, can also be used. The neutralizing cation
for the anionic synthetic sulfonates and/or sulfates is represented by conventional
cations which are widely used in detergent technology such as sodium, potassium, lithium,
amines and substituted amines. Preferred are sodium, mono-, di- and tri-ethanol amines.
[0023] A particularly preferred anionic synthetic surfactant component herein is represented
by the water-soluble salts of an alkylbenzene sulfonic acid, preferably sodium or
alkanolamine alkylbenzene sulfonates having from about 10 to 13 carbon atoms in the
alkyl group.
[0024] A preferred class of nonionic ethoxylates is represented by the condensation product
of a fatty alcohol having from 12 to 15 carbon atoms and from about 4 to 10 moles
of ethyle.ne oxide per mole of fatty alcohol. Suitable species of this class of ethexylates
include: the condensation product of C
12-C
15 oxc-alcohols and 7 moles of ethylene oxide per mole of alcohol; the condensation
product of narrow cut C
14-C
15. oxo-alcohols and 7 or 9 moles of ethylene oxide per mole of fatty (oxo) alcohol;
the condensation product of a narrow cut C
12-C
13 fatty (oxo) alcohol and 6,5 moles of ethylene oxide per mole of fatty alcohol; and
the condensation products of a C
10-C
14 coconut fatty alcohol with a degree of ethoxylation (moles EO/mole fatty alcohol)
in the range from 5 to 8. The fatty oxo alcohols while mainly linear can have, depending
upon the processing conditions and raw material olefins, a certain degree of branching,
particularly short chain such as methyl branching. A degree of branching in the range
from 15% to 50% (weight %) is frequently found in commercial oxo-alcohols.
[0025] Preferred nonionic ethoxylated components can also be represented by a mixture of
2 separately ethoxylated nonionic surfactants haying a different degree of ethoxylation.
For example, the nonionic ethoxylate surfactant containing from 3 to 7 moles of ethylene
oxide per mole of hydrophobic moiety and a second ethoxylated species having from
8 to 14 moles of ethylene oxide per mole. of hydrophobic moiety. A preferred nonionic
ehtoxylated mixture contains a lower ethoxylate which is the condensation product
of a C
12-C
15 oxo-alcohol, with up to 50.% (wt) branching, and from about 3 to 7 moles- of ethylene
oxide per mole of fatty oxo-alcohol, and a higher ethoxylate which is the condensation
product of a C
16-C
19 oxo-alcohol with more than 50% (wt) branching and from about 8 to 14 moles of ethylene
oxide per mole of branched oxo-alcohol.
The Saturated Fatty Acid.
[0026] The saturated fatty acid component herein is incorporated in an amount of from about
3% to about 15%, preferably from about 5% to about 11%. The saturated fatty acids
have from 10 to 16, preferably 12 or 14 carbon atoms in the alkyl chain. The most
preferred fatty acids are either lauric acid or lauric and myristic fatty acid in
a mixture of 5:1 to 1:1. It is understood that in addition to the saturated fatty
acids, the compositions herein can comprise certain amounts of unsaturated fatty acids
having, for example, 16 or 18 carbon atoms in the alkyl chain. Known examples of the
like unsaturated fatty acids are oleic fatty acid and palmitoleic fatty acid.
The Enzyme.
[0027] The enzyme component herein is incorporated in an amount of from about 0.025 to about
1%, preferably from about 0.05% to about 0.2%. The preferred proteolytic enzyme component
should give to the composition a proteolytic activity of at least about 4 Anson units,
preferably from about 8 to about 30 Anson units, most preferably from about 10 to
about 20 Anson units per kilo of the liquid detergent composition. In another preferred
embodiment the enzyme component can be represented by a mixture of proteases and amylases.
The proteolytic activity of that mixture is as defined herein- hefore.
[0028] Preferably the enzyme component is characterized by an isoelectric point of from
about 8.0 to about 10, preferably from about 8.5 to about 9.5.
[0029] Examples of suitable proteolytic enzymes include many species which are known to
be adpated for use in detergent compositions and, in fact, have been used in detergent
compositions. Sources of the enzymes include commercial enzyme preparations such as
"ALCALASE" sold by Novo Industries, and "MAXATASE" sold by Gist-Brocades, Delft, The
Netherlands, which contain about 20% enzyme. Other preferred enzyme compositions include
those commercially available under the tradenames SP-72 ("Esperase") manufactured
and sold by Novo Industries, A/S, Copenhagen, Denmark and "AZ-Protease" manufactured
and sold by Gist-Brocades, Delft, The Netherlands.
[0030] A more complete disclosure of suitable enzymes can be found in 'U.S. Patent 4,101,457,
Place et al., issued July 18, 1978, incorporated herein by reference.
The Carboxylic Acid.
[0031] A further essential component herein is represented by a short chain carboxylic acid
having from 1 to 3 carbon atoms. This ingredient is used in an amount from 0.1% to
about 3%, preferably from 0,5% to 1,5% by weight. The carboxylic acid component can
be represented by formic, acetic and propionic acid. Preferred are the water-soluble
salts. Most preferred is formic acid or the formates such as sodium, potassium, lithium,
amines and substituted amines, inclusive of mono-, di-, and tri-ethanolamines.
The Enzyme-Accessible Calcium.
[0032] The compositions herein comprise less than about 2, preferably from 0.5 to 1.5, millimoles
of enzyme-accessible calcium per kilo of the homogeneous enzyme containing detergent
product. The claimed compositions are substantially free of sequestrants, for example,
polyacids capable of forming calcium complexes which are soluble in the composition.
However, minor amounts of sequestrants such as polyacids or mixtures of polyacids
can be used. The enzyme-accessible calcium is defined as the amount of calcium-ions
effectively available to the enzyme component. The calcium sequestration resulting
from e.g., 0.5% of a mixture of polyphosphonates and polyacids as exemplified hereinafter
can represent about 1 to about 1.5 millimoles of calcium per kilo of product. The
total calcium incorporated into the compositions is thus comprised of the enzyme-accessible
calcium and also the calcium sequestered by the low levels of polyacids. From a practical
standpoint the enzyme-accessible calcium is therefore the soluble calcium in the composition
in the absence of any strong sequestrants, e.g., having an equilibrium constant of
complexation with calcium equal to or greater than 1.5 at 20°C.
Product pH.
[0033] The pH of the product is from about 6.5 to about 8.5 preferably from about 7 to about
7.5 to obtain a combination of enzyme stability and detergency. Both high and low
pH's can adversely affect enzyme stability.
Optional Components.
[0034] In addition to the essential ingredients described hereinbefore, the compositions
herein frequently contain a series of optional ingredients which are used for the
known functionality in conventional levels. While the inventive compositions are premised
on aqueous enzyme-containing detergent compositions containing a critical ternary
system as fully explained above, it is frequently desirable to use a phase regulant
This component together with water constitutes then the solvent matrix for the claimed
liquid compositions. Suitable phase regulants are well-known in liquid detergent technology
and, for example, can be represented by lower aliphatic alcohols having from 2 to
6 carbon atoms and from 1 to 3 hydroxyl groups, ethers of diethylene glycol and lower
aliphatic monoalcohols having from 1 to 4 carbon atoms. Specific examples of phase
regulants are: ethanol; n-propanol; isopropanl; butanol; 1,2-propanediol; 1,3-propanediol;
n-hexanol; monomethyl-, -ethyl-, -propyl, and mono-butyl ethers and di-ethylene glycol.
Additional phase regulants having a relatively high boiling point and low vapor pressure
can also be used provided they.do not react with the other ingredients of the compositions.
[0035] Known detergent hydrotropes are a further class of phase regulants suitable for use
herein. Examples of these hydrotropes include salts of alkylarylsulfonates having
up to 3 carbon atoms in the alkylgroup, e.g., sodium, potassium, ammonium and ethanolamine
salts of xylene-, toluene-, ethylbenzene-, cumene-, and isopropylbenzene sulfonic
acids. The phase is frequently used in an amount from about 5% to about 20%; the sum
of phase regulant and water is normally in the range from 65% to 35%. The compositions
herein can contain a series of further optional ingredients which are mostly used
in additive levels, usually below about 5%. Examples of the like additives include:
polyacids, suds regulants, opacifiers, antioxidants, bactericides, dyes, perfumes,
brighteners and the like.
[0036] A preferred additive is represented by a polyacid or mixture of polyacids in an amount
below about 1%. Suitable polyacids can include: citric, cyclohexane-1,1-dicarboxylic,
cyclopropane-1,1-dicarboxylic, dimethylmalic, glutaric, o-hydroxybenzoic, m-hydroxybenzoic,
p-hydroxybenzoic, itaconic, methylsuccinic, sodium tripolyphosphates, and nitrilotriacetic
acid. Preferred polyacid species for use herein can be represented by citric acid
and organo-phosphonic acids and mixtures thereof. Particularly preferred alkylene-polyamino-polyalkylene
phosphonic acids are ethylene diamine tetrame- thylenephosphonic acid, hexamethylene
diaminetetramethylene- phosphonic acid, diethylene triaminepentamethylenephosphonic
acid, and amino-trimethylenephosphonic acid or the salts thereof. These organophosphonic
acids/salts are preferably used in an amount from 0.1%-0.8%.
[0037] The beneficial utilization of the claimed compositions under various usage conditions
can require the utilization of a suds regulant. While generally all detergent suds
regulants can he utilized preferred for use herein are alkylated polysiloxanes. such
as dimethylpolysiloxane also frequently termed silicone. The silicones are frequently
used in a level not exceeding 0.5%, most preferably between 0.01% and 0.2%.
[0038] It can also be desirable to utilize opacifiers inasmuch as they contribute to create
a uniform appearance of the concentrated liquid detergent compositions. Examples of
suitable opacifiers include: polystyrene commercially known as LYTRON 621 manufactured
by MONSANTO CHEMICAL CORPORATION. The opacifiers are frequently used in an amount
from 0,3% to 1,5%.
[0039] The compositions herein can also contain known antioxidants for their known utility,
frequently radical scavengers, in the art established levels i.e. 0,001% to 0,25%
(by reference to total composition). These antioxidants are frequently introduced
in conjunction with the fatty acids. While many suitable antioxidants are readily
known and available for that purpose especially preferred for use in the compositions
herein are: 2,6 ditertiary butyl-p-cresol, more commonly known as butylated hydroxytoluene,
BHT, and 2-tertiarybutyl-4-hydroxyanisole or 3-tertiarybutyl-4-hydroxyanisole more
commonly known as BHA or butylated hydroxyanisole. Other suitable antioxidants are:
4,4'thiobis(6-tert-butyl-m-cresol) and 2-methyl-4,6-dinonyl phenol.
[0040] The following examples illustrate the invention and facilitate its understanding.
EXAMPLE
[0041] Liquid detergent compositions were prepared by mixing the listed ingredients in the
stated proportions.
[0042] The enzyme and physical stability of the listed compositions were determined under
accelerated storage conditions after 2 weeks at 35°C. Composition A is representative
of the prior art, Compositions B and C are reference compositions based on routine
variations vs. the art compositions. Composition I is an example of the invention
herein. The level of calcium in compositions A and B represents, based on current
art knowledge, the minimum needed to achieve acceptable enzyme stability. The amount
of calcium in composition C was lowered to the point where phase instability and precipitation
would not anymore_occur. The testing data are summarized below.
[0043] These results confirm the overall performance benefits provided by composition I
in accordance with this invention vs. formulationwise closely related art composition
--A-- or what could be technical variations --B, C-- of known art formulations.
[0044] Comparable performance benefits are obtained from the above compositions wherein
the formic acid is replaced with an identical molar proportion of acetic acid or propionic
acid.
[0045] Further compositions of this invention were prepared by mixing the listed components
in the indicated proportions.
[0046] Composition D is what could be a technical variation of the state of art whereas
formulae II and III are executions of the claimed invention.
[0047] The residual enzymatic activity (expressed in % of initial activity) were measured
following exposure to accelerated storage conditions (48 hours at 40°C).
[0048] The testing results were as follows:
[0049] These results. verify the superiority of the claimed technology vs. closely related
compositions and also show that formic acid is the most preferred short chain carhoxylic
acid,
[0050] A series of additional compositions of this invention are prepared by mixing the
listed ingredients in a conventional manner.
[0051] Compositions IV - X are clear, homogeneous products having a markedly improved enzyme
stability, especially upon storage.