Note: Descriptions are shown in the official language in which they were submitted.
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20(~7381
LIOUID DETERGENT COMPOSITION CONTAINING ENZYME
AND ENZYME STABILIZATION SYSTEM
Chris THOEN
TECHNICAL FIELD
The present invention relates to a stabilization system
for detergent enzymes. More particularly, it relates to a
stabilization system for detergent enzymes in an aqueous
liquid detergent composition which further contains a
peroxygen bleach.
BACKGROUND OF THE INVENTION
EP 88-201009.3 discloses aqueous liquid detergent
compositions containing a peroxygen bleach. The compo-
sitions are designed to limit the amount of available
oxygen in solution. Enzyme-containing co"l~ositions are
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disclosed. The patent document does not disclose stabili-
zation systems for the enzymes. At the time of filing of
the present patent application, no publication of EP
88-201009.3 has taken place.
EP 28 865 discloses a stabilization system for enzymes
in a liquid detergent composition comprising formic acid or
a salt thereof and calcium ions. The disclosed
compositions have a pH of from 6.5 to 8.5.
:
SUMMARY OF THE INVENTION
Unless otherwise specified, all percentages in the
following are by weight.
The present invention relates to aqueous liquid detergent
compositions comprising from 5 % to 60 % of an organic
surfactant; from l % to 40 % of a peroxygen compound; a
detergent enzyme; characterized in that it further
comprises, as an enzyme stabilizing system, from 0.01 % to
15 % of a carboxylic acid of the formula X-R-COOH where X
is H, OH or COOH and R is an unsubstitued or hydroxy
substitued C1 to Cg alkyl, alkenyl, alkynyl or aryl
group; and mixtures of said acids.
Preferred comro~itions have a pH of at least 8.5, more
preferably at least 9.0, most preferably at least 9.5 .
The peroxygen compound preferably is a perborate, most
preferably perborate tetrahydrate.
Preferred composition contain a water-miscible organic
solvent such as ethanol. This reduces the solubility of
any dispersed peroxygen compound, resulting in a low level
of available oxygen in the liquid phase that is controlled
to be under 0.5 %, preferably below 0.1 %.
The amount of carboxylic acid enzyme stabilizer
preferably is from 0.5% to 10%, most preferably from 1% to
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7.5%. Preferred enzyme stabilizers are acetic acid,
propionic acid and adipic acid. Most preferred is adipic
acid. According to the invention, mixture of these acids
with formate is also suitable
Suitable detergent enzymes include detergent
proteases,detergent amylases, detergent lipases and
detergent cellulases. Preferred detergent compositions
herein are those that contain a detergent protease,
preferably a high alkaline protease, from 0.01 ~ to 5 % on
8 KNPU/g basis, most preferably from 0.05 % to 2.5 %
The detergent compositions optionally contain, as a
second enzyme stabilizer, from 0.01 % to 5 % magnesium
ions, preferably from 0.1 % to 0.5 %.
DETAILED DESCRIPTION OF THE INVENTION
In spite of their rapidly growing popularity, liquid
detergent compositions available to date do not fully match
the performance profile of high quality granular
detergents, particularly of those containing a peroxygen
bleach and detergent enzymes. It is, therefore, desirable
to provide liquid detergent compositions that contain both
a peroxygen bleach and detergent enzymes. Ways of doing so
have been provided in our earlier patent application, EP
88-201009.3
It has now been found that detergent enzymes present in
aqueous, peroxygen bleach-containing liquid detergents are
subject to two types of deactivation mechanisms. The first
mechanism involves auto-hydrolysis of the enzyme, and could
be referred to as autolysis. This type of deactivation is
rather well known in the detergent industry, and several
enzyme stabilization systems have been proposed to reduce
its effects. Autolysis becomes more of a problem as the pH
of the liquid detergent composition increases. On the
other hand, a high pH is conducive to a good performance of
the peroxygen bleach.
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The second mechanism of enzyme deactivation involves
the oxidation of certain amino acids in the enzyme. This
mechanism is specific to liquid detergents containing
peroxygen bleach upon storage, and has heretofore not been
recognized in the detergent industry.
An enzyme stabilization system for use in aqueous
liquid detergent compositions which contain a peroxygen
bleach should protect the enzyme against both autolysis and
oxidative deactivation. Formic acid appears to protect
against autolysis, but not against oxidative deactivation.
It has now surprisingly been found that certain
carboxylic acids, to wit, acids of the formula X-R-COOH,
where X is H, OH or COOH and R is an unsubstitued or
hydroxy substitued C1 to Cg alkyl, alkenyl, alkynyl or
aryl group protect enzymes against both oxidative
deactivation and autolysis. Of course, these carboxylic
acids become partially or totally deprotonated at the pH of
the detergent composition, particularly when the pH of the
composition is greater than 8.5, as is preferred for
peroxygen bleach performance. Unless stated otherwise, the
word "carboxylic acid" as used herein encomr~ssPs the
deprotonated species and salts as well. The percentages
herein are weight percentages, calculated on the basis of
the protonated acid.
In practice, the acid or a water-soluble salt of the
acid is added to the co~o~ition, and the cn~rosition's pH
is adjusted to its desired value, using customary alkaline
or acidic materials, as the case may be. As an
alternative, the acid or its water soluble salt may be
premixed with the enzyme hereinafter described, before
being introduced into the composition. Said premix may
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also be evaporated or lyophylised so as to obtain solid
particles which may be coated with, e.g. silicone oil. For
the present purposes, the enzyme stabilizing compound will
be referred to as the acid, even if it is present or added
in the form of one of its salts.
It is understood that, according to the invention, mixtures
of said acids can also be used.
It is also possible to premix the acid with the enzyme
and then add the premix to the composition; in that case,
lower acid concentrations can be obtained in the final
c~rositions
Preferred compositions contain carboxylic acids
selected from acetic acid, propionic acid, adipic acid, and
mixtures thereof.
The liquid detergent compositions herein all contain
from 5 ~ to 60 % by weight of the liquid detergent
composition, preferably from 15 % to 40 % of an organic
surface-active agent selected from nonionic, anionic,
cationic, and zwitterionic surface-active agents and
mixtures thereof.
Synthetic anionic surfactants can be ~e~Lesented by the
general formula R1S03M wherein R1 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 is
typically selected from the group consisting of sodium,
potassium, ammonium, and mixtures thereof.
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A preferred synthetic anionic surfactant is a
watersoluble salt of an alkylbenzene sulfonic acid
containing from 9 to 15 carbon atoms in the alkyl group.
Another preferred synthetic anionic surfactant is a
water-soluble salt of an alkyl sulfate or 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 from about 1 to
about 20, preferably from 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.
The nonionic surfactants are conventionally produced by
condensing ethylene oxide with a hydrocarbon having a
reactive hydrogen atom, e.g. a hydroxyl, carboxyl, or amino
group, in the presence of an acidic of basic catalyst, and
include compounds having the general formula
RA(CH2CH20)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. They 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.
The hydrophobic moiety of the nonionic compound is
preferably a primary or secondary, straight or branched,
aliphatic alcohol having from about 8 to 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. Mixtures of nonionic surfactants
can be desirable.
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Suitable cationic surfactants include quaternary
ammonium compounds of the formula RlR2R3R4N+
where Rl, R2, and R3 are methyl groups and R4 is a
C12-C15 alkyl group, or where R1 is an ethyl or
hydroxy ethyl group, R2 and R3 are methyl groups and
R4 is a C12-C15 alkyl group.
Zwitterionic surfactants include derivatives of
aliphatic quaternary ammonium, phosphonium, and sulphonium
compounds in which the aliphatic moiety can be a straight
or branched chain and wherein one of the aliphatic
substituents contains from about 8 to about 24 carbon atoms
and another substituent contains, at least, an anionic
water-solubilizing group. Particularly preferred
zwitterionic materials are the ethoxylated
ammoniumsulfonates 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.
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.
Suitable anionic synthetic surface-active salts are
selected from the group of sulfonates and sulfates. The
like anionic detergents are well-known in the detergent
arts and have found wide-spread application in commercial
detergents. Preferred anionic synthetic water-soluble
sulfonate of sulfate salts have in their molecular
structure an alkyl radical containing from about 8 to about
22 carbon atoms.
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Examples of such preferred anionic surfactant salts are
the reaction products obtained by sulfating C8-C18
fatty alcohols derived from tallow and coconut oil;
alkylbenzene sulfonates wherein the alkyl group contains
from about 9 to 15 carbon atoms; sodium alkylglyceryl ether
sulfonates; ether sulfates of fatty alcohols derived from
tallow and coconut oils; coconut fatty acid monoglyceride
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
3,332,880 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 and potassium.
A particularly preferred anionic synthetic surfactant
component herein is represented by the water-soluble salts
of an alkylbenzene sulfonic acid, preferably sodium
alkylbenzene sulfonates having from about 10 to 13 carbon
atoms in the alkyl group.
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 2 to 10,
preferably 3 to 7 moles of ethylene oxide per mole of fatty
alcohol. Suitable species of this class of ethoxylates
include : the condensation product of C12-C15
oxo-alcohols and 7 moles of ethylene oxide per mole of
alcohol; the condensation product of narrow cut C14-C15
oxo-alcohols and 7 or 9 moles of ethylene oxide per mole of
fatty(oxo)alcohol; the condensation product of a narrow cut
C12-C13 fatty(oxo)alcohol and 6,5 moles of ethylene
oxide per mole of fatty alcohol; and the condensation
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g
products of a C10-Cl4 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 co~Drcial oxo alcohols.
Preferred nonionic ethoxylated components can also be
represented by a mixture of 2 separately ethoxylated
nonionic surfactants having 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
ethoxylated mixture contains a lower ethoxylate which is
the condensation product of a C12-C15 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
C16-Clg oxo-alcohol with more than 50 % (wt) branching
and from about 8 to 14 moles of ethylene oxide per mole of
branched oxo-alcohol.
Suitable bleaches in the present compositions are
solid, water-soluble peroxygen compounds. Preferred
compounds include perborates, persulfates,
peroxydisulfates, perphosphates and the crystalline
peroxyhydrates formed by reacting hydrogen peroxyde with
sodium carbonate or urea. Preferred peroxygen bleach
compounds are sodium perborate monohydrate and sodium
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perborate tetrahydrate and sodium percarbonate. Perborate
bleaches in the present composition can be in the form of
small particles i.e. from 0,1 to 20 micrometers, said
particles having been formed by in situ crystallization of
the perborate.
The term "in situ crystallization" relates to processes
whereby perborate particles are formed from larger
particles or from solution, in the presence of the
water/anionic surfactant/detergent builder matrix. This
term therefore encompasses processes involving chemical
reactions, as when sodium perborate is formed by reacting
stoichiometric amounts of hydrogen peroxide and sodium
metaborate or borax. It also encompasses proce~-cPs
involving dissolution and recrystallization, as in the
dissolution of perborate monohydrate and subsequent
formation of perborate tetrahydrate. Recrystallization may
also take place by allowing perborate monohydrate to take
up crystal water, whereby the monohydrate directly
recrystallizes into the tetrahydrate, without dissolution
step.
In one embodiment of the invention, a perborate
compound, e.g., sodium perborate monohydrate, is added to
an aqueous liquid comprising the anionic surfactant and the
detergent builder. The resulting slurry is stirred.
During this stirring the perborate compound undergoes a
process of dissolution/recrystallization. Due to the
presence of the anionic surfactant and the detergent
builder this dissolution/recrystallization process results
in particles having the desired particle diameter.
As the monohydrate is more susceptible to
recrystallization, the monohydrate is preferred for this
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embodiment of the invention. Particle diameters herein are
weight average particle diameters, unless otherwise
specified. For reasons of physical stability it is
preferred that the particle size distribution is relatively
narrow; i.e., it is preferred that less than 10 % (wt) has
a particle diameter greater than 10 micrometers.
In a second embodiment of the invention the perborate
compound is formed in situ by chemical reaction. For
example, sodium metaborate is added to an aqueous liquid
comprising the anionic surfactant and the detergent
builder. Then a stoichiometric amount of hydrogen peroxide
is added while stirring. Stirring is continued until the
reaction is complete.
Instead of metaborate, other borate compounds,
including e.g., borax and boric acid can be used. If borax
is used as the boron compound, a stoichiometric amount of a
base, e.g. sodium hydroxide, is added to ensure reaction of
the borax to metaborate. The process then proceeds as
described hereinabove for metaborate conversion. Instead
of hydrogen peroxide, other peroxides may be used (e.g.,
sodium peroxide), as known in the art.
Preferred liquid detergent compositions contain, in
addition to water, a water-miscible organic solvent. The
solvent reduces the solubility of perborate in the liquid
phase and thereby enhances the chemical stability of the
cn~rocition.
It is not necessary that the organic solvent be fully
miscible with water, provided that enough of the solvent
mixes with the water of the c~mpo~ition to affect the
solubility of the perborate compound in the liquid phase.
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The water-miscible organic solvent must, of course be
compatible with the perborate compound at the pH that is
used. Therefore, polyalcohols having vicinal hydroxy
groups (e.g. l,2-propanediol and glycerol) are less
desirable.
Examples of suitable water-miscible organic solvents
include the lower aliphatic monoalcohols, and ethers of
diethylene glycol and lower monoaliphatic monoalcohols.
Preferred solvents are ethanol, iso-propanol, l-methoxy,
2-propanol, butyldiglycolether and ethyldiglycolether.
The compositions according to the invention also
contain detergent enzymes; suitable enzymes include the
detergent proteases, amylases, lipases, cellulases and
mixtures thereof. Preferred enzymes are high alkaline
proteases e.g. Maxacal (R) and Savinase tR).
Silicone-coated enzymes, as described in EP-A-0238216 can
also be used.
Preferred c~m~o~itions herein optionally contain as a
builder a fatty acid component. Preferably, however, the
amount of fatty acid is less than S % by weight of the
c~mrosition, more preferably less than 4 %. Preferred
saturated fatty acids have from 10 to 16, more preferably
12 to 14 carbon atoms. Preferred unsaturated fatty acids
are oleic acid and palmitoleic acid.
Preferred compositions contain an inorganic or organic
builder. Examples of inorganic builders include the
phosphorous-based builders, e.g., sodium tripolyphosphate,
sodium pyrophosphate, and aluminosilicates (zeolites).
Examples of organic builders are represented by
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polyacids such as citric acid, nitrilotriacetic acid, and
mixtures of tartrate monosuccinate with tartrate
disuccinate. Preferred builders for use herein are citric
acid and alk(en)yl-substituted succinic acid compounds,
wherein alk(en)yl contains from 10 to 16 carbon atoms. An
example of this group of compounds is dodecenyl succinic
acid. Polymeric carboxylate builders inclusive of
polyacrylates, polyhydroxy acrylates and
polyacrylates/polymaleates copolymers can also be used.
The compositions herein can contain a series of further
optional ingredients which are mostly used in additive
levels, usually below about S %. Examples of the like
additives include : suds regulants, opacifiers, agents to
improve the machine compatibility in relation to
enamel-coated surfaces, bactericides, dyes, perfumes,
brighteners and the like.
The liquid compositions herein can contain further
additives of a level from 0,05 % to 5 %.
These additives include polyaminocarboxylates such as
ethylenediaminotetracetic acid, diethylenetriamino-
pentacetic acid, ethylenediamino disuccinic acid or the
water-soluble alkali metals thereof. Other additives
include organo-phosphonic acids; particularly preferred are
ethylenediamino tetramethylenephosphonic acid,
h~x~m~thylenediamino tetramethylenephosphonic acid,
diethylenetriamino pentamethylenephosphonic acid and
aminotrimethylenephosphonic acid.
Bleach stabilizers such as ascorbic acid, dipicolinic
acid, sodium stannates and 8-hydroxyquinoline can also be
included in these compositions, at levels from O.O1 % to
1 %.
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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 be utilized preferred for use herein are
alkylated polysiloxanes such as dimethylpolysiloxane also
frequently termed silicones. The silicones are frequently
used in a level not exceeding 1.5 %, most preferably from
0.1 % to 1.0 %.
It can also be desirable to utilize opacifiers in as
much 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 %.
The liquid detergent compositions of this invention can
further comprise an agent to improve the washing machine
compatibility, particularly in relation to enamel-coated
surfaces.
It can further be desirable to add from 0.1 % to 5 % of
known antiredeposition and/or compatibilizing agents.
Examples of the like additives include : sodium
carboxymethylcellulose; hydroxy-Cl_6-alkylcellulose;
polycarboxylic homo- or copolymeric ingredients, such as :
polymaleic acid; a copolymer of maleic anhydride and
methylvinylether in a molar ratio of 2:1 to 1:2; and a
copolymer of an ethylenically unsaturated monocarboxylic
acid monomer, having not more than 5, preferably 3 or 4
carbon atoms, for example (meth)-acrylic acid, and an
ethylenically unsaturated dicarboxylic acid monomer having
not more than 6, preferably 4 carbon atoms, whereby the
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200738 ~
molar ratio of the monomers is in the range from 1:4 to
4:1, said copolymer being described in more detail in
European Patent ~blication No. 0,066,915, ~ublished Dec. 15, 1982.
The following examples illustrate the invention and
facilitate its understanding.
Liquid detergent compositions were prepared by mixing
the listed ingredients in the stated proportions. The pH
of these compositions is in the range of from 9.5 to 10.5.
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