Note: Descriptions are shown in the official language in which they were submitted.
4~
62301-138
BACKGROUND OF THE INVENTION
This invention relates to stable, built, enzyme-
containing liquid detergent compositions suitable for laundry
or pre-soak formulations. More particularly, the invention
relates to aqueous enzyme-containing liquid detergent CoMposi-
tions which contain one or more detergent builders and which
are characterized by being physically stable, homogeneous
liquid compositions.
The formulation of stabilized enzyme-containing
liquid detergent compositions has been the focus of much atten-
tion in the prior art. The desirability oE incorporating
enzymes into detergent composi-tions is primarily due to the
effectiveness of proteolytic and amylolytic enzymes in decompo-
sing proteinaceous and starchy materials found on soiled fab-
rics, thereby facilitating the removal of s-tains, such as,
gravy stains, blood stains, chocolate stains and the like dur-
ing laundering. However, enzymatic ma-terials sui-table for
laundry compositions, particularly proteolytic enzymes, are
relatively expensive. Indeed, they generally are among the
most expensive ingredients in a typical commercial liquid de-
tergent composition, even though they are present in relatively
minor amounts. Moreover, enzymes are known to be unstable in
aqueous compositiorls. It is for this reason that an excess of
enzymes is generally required in liquid detergent formulations
to compensate for the expected loss of enzyme activity during
prolonged periods of storage. Accordingly, the prior art is
replete with suggestions for stabilizing enzyme-containing
liquid detergent compositions, and in particular unbuilt liquid
compositions by the use of various materials which are incorpo-
rated into the composition to function as enzyme stabilizers.
- 2 -
~;29~4 ~
62301~1384
In the case of liquid detergent compositions contain-
ing a builder, the problem of enzyme instability is particular-
ly acute. Primarily this is because detergent builders have a
destabilizing effect on enzymes, even in compositions contain-
ing enzyme stabilizers which are otherwise effective in unbuilt
formulations. Moreover, the incorporation of a builder into a
liquid detergent composition poses an additional problem, name-
ly, the ability to form a stable single-phase composition' the
solubility of sodium tripolyphosphate, for example, being rela-
tively limited in aqueous compositions, and especially in thepresence oE anionic and nonionic detergents.
ln V.K. Patent Application G.B. 2,079,305, publ;shed
January 20, 19~2, there is disclosed an aqueous built enzyme-
containing liquid detergent composition which is stabilized by
a mixture of a polyol and boric acid. As noted in the examples
of the U.K. application, relatively large amounts of glycerol
are required to stabiliæe -the enzymes in the composition. Yet,
as demonstrated hereinafter in the present specification, -the
enzyme stabilizing effect provided by a mixture of glycerine
and borax in a built aqueous liquid detergent composition is
relatively modest.
,~ 3 -
g2~7~
62301-13
SUMMARY OF THE INVENTION
The present invention provides a stabilized fabric
softening built, enzyme-containing liquid detergent composition
comprlslng:
(a) from about 5 to 20%, by weight, of one or more sur-
face active detergent compounds selected from the
: group consisting o~ anionic, nonionic and amphoteric
detergent compounds;
(b) from about 5 to 30~, by weight, of one or more build-
er salts selected from the group consisting of alkali
metal tripolyphosphates, alkali metal carbonates,
alkali metal nitri].otr:iacetates, ~nd polyacetal c~r--
boxylates;
(c) from about 5 to 20%, by weight, of a swelling benton-
ite clay;
(d) an effective amount of an enzyme or an enzyme mixture
selected from the group consisting of alkaline pro-
tease enzymes and alpha-amylase enzymes;
(e) an enzyme-stabilizing system containing, based on the
weigh-t oE the detergent composition, (i) from about 1
to 10% glycerine; (ii) from about 1 to 8% of a boron
compound selected from the group consisting of boric
acid, boric oxide and alkali metal borates and; (iii)
from about 0.5 to 8% of a carboxylic acid compound
selected from the group consisting of mono, di and/or
polycarboxylic acids having 1 to 8 carbon atoms and
water-soluble salts thereof, and
(f) the balance comprising water and optionally perfume
and other adjuvants.
~2~7~L.~CI
62301-1384
In a preferred embodiment of the invention, the
liquid detergent composition comprises
(a) from about 5 to 15% of an alkali metal alkyl-benzene
sulfonate wherein the alkyl group contains 12 to 15
carbon atoms'
(b) from about O.S to 5% of an alkali metal alkyl poly-
ethoxy sulfate wherein the alkyl group contains 10 to
18 carbon atoms and the polyethoxy is of 3 to 11
ethylene oxide groups, the weight ratio of (a) to (b)
being from about 2:1 to about 6:1;
(c) from about 5 to 20% of sodium tripolypllosphate;
(d) from about 1 to 10~ oE sodium carbonate, sodium bi-
carbonate or mixtures thereof, the weight ratio of
(c) to (d) being from about 2:1 to about 6:1;
(e) from about 10 to 15~ of a sodium bentonite,
(f) an effective amount of the aforesaid enzyme or enzyme
mixture;
(g) an enzyme stabilizing system containing, based on the
weight of the detergent composition, (i) from about 1
to 5% glycerine (ii) from about 1 to 5% of an alkali
metal borate and (iii) from about 0.5 to 4% of said
carboxylic acid compound; and
(h) the balance comprising water and optionally perfume
and other adjuvants.
In accordance with the process of the invention,
laundering of stairled and/or soiled materials is affected by
contacting such materials with an aqueous solution of the
above-defined liquid detergent compositions.
62301-1384
The described liquid detergent is a commercially
acceptable heavy duty laundry detergent, capable of satisfact-
orily cleaning laundry items containing both oily and particu-
late soils. Addi-tionally, the described compositions may be
employed for the pre-treatment of badly soiled areas, such as
collars and cuffs, of items to be laundered.
The present invention is predicated upon the discov-
ery of a three component enzyme stabilizing system as herein
defined which provides an enzyme stabilizing effect to the
liquid detergent compositions of the invention far in excess of
that which can be achievecl with conventional enzyme stabili-
zers. The enzyme stabilizing effect thus achieved reElects a
synergy among the three components. In accordance with the
invention, the enzyme stability provided by a mixture of
glycerine and borax or a mixture of borax and a dicarboxylic
acid as disclosed in the prior art can be synergistically
improved by the use of the three component stabilizing system
herein defined in the present liquid compositions so as to
raise the level of enzyme stability significantly above that
provided by either the mixture of glycerine and borax or the
mixture of borax and dicarboxylic acid when used independently
of each other as enzyme stabilizers. For commercial purposes,
a desirable enzyme stability generally corresponds -to about a
half-life of one week at a temperature of 110F.
~29~0
6230~-1384
DETAILED D~SCRIPTION OF THE I~VENTIO~
The enzyme stabilizing system of the invention is a
mixture of glycerine, a boron compound selected from among
boric acid, boric oxide and an alkali metal borate and a car-
boxylic acid compound as herein defined. The weight of the
stabilizing system in the present built liquid detergent compo-
sitions is generally from about 3 to 25%, preferably about 6 to
15~, by weight. The weight ratio of glycerine to borax in the
stabilizing mixtures is generally from about 0.5 to 3. The
preferred amount of glycerine in the composition is ~rom about
1 to 5~, the preferred amount of boron compound is from about 1
to 5%, and the preferred amount of carboxylic compound is Erom
about 0.5 to 4~ based on the weight of the composition.
The carboxylic acid compounds which are useful in the
enzyme stabilizing system of the invention encompass saturated
as well as unsaturated mono, di and polycarboxylic acids having
1 to 8 carbon atoms among which are included oxalic acid
(HOOCCOOH), malonic acid (HOOCCH2COOH), maleic acid
(HOOCCH:CHCOOH) and succinic acid (HOOCCH2CH2COOH). The
carboxylic acids may contain hydroxy or amino substituents as
exemplified by malic acid (HOOCCHOHCH2COOH), tartaric acid
(dihydroxysuccinic acid) aspartic acid (amino succinic acid)
and citric acid. Preferred carboxylic acids of the invention
are aspartic acid, tartaric acid, malonic acid and malic acid.
From a commercial standpoint, a particularly preferred carboxy-
lic acid compound is citric acid and/or its salts because of
their relatively low cost.
The alkaline proteolytic enzymes suitable for the
present compositions include the various commercial liquid
. . .
12~7~ 1~
62301-138~
enzyme preparations which have been adapted for use in deter-
yent compositions. Enzyme preparations in powdered form are
also useful although, as a general rule, less convenient Eor
incorporation into the built liquid detergent compositions.
Thus, suitable liquid enzyme preparations include "Alcalase"
and "Esperase" sold by ~ovo Industries, Copenhagen, Denmark,
and "~axatase" and "AZ-Protease" sold by Gist-Brocades, Delft,
The Netherlands.
AMong the suitable~ -amylase liquid enzyme prepara~
tions are -those sold by Novo Industries and Gist-Brocades under
the tradenames "Termamyl" and "Maxamyl", respectively.
"Esperase" is particularly preferred for the present
compositions because of its optimized activity at the higher pH
values corresponding to the built detergent compositions.
The preferred detergents for use in the present
liquid compositions are the synthetic anionic detergent com-
pounds, and particularly a mixture of higher alkylben~.ene
sulfonate and alkyl polyethoxy sulfate. While other water
soluble higher alkylbenzene sulfonates may also be presen-t in
the instant formulas, such as potassium salts and in some
instances the ammonium or alkanolammonium salts, where
appropriate, it has been found that the sodium salt is highly
preferred, which is also the case with respect to khe alkyl
polyethoxy sulfate detergent component. The alkylbenzene
sulfonate is one wherein the higher alkyl is of 12 to 15 carbon
atoms, preferably 13 carbon atoms. The alkyl polyethoxy
sulfate, which also may be referred to as a sulfated
polyethoxylated higher linear alcohol or the sulfated
condensation product of a higher fatty alcohol and ethylene
oxide or polyethoxylene glycol, is one wherein the
3L2~74~
62301-13~4
alkyl is of 10 to 18 carbon atoms, preferably 12 to 15 carbon
atoms, e.g., abou-t 13 carbon atoms, and which includes 3 to 11
ethylene oxide groups, preferably 3 to 7, more preferably 3 to
5 and most preferably 3 or about 3 ethylene oxide groups. The
ratio of alkylbenzene sulfonate to polyethoxy sulfate in the
detergent mixture is preferably from about 2:1 to 6:1 and most
preferably from about 2:1 to ~:1, by weight. A~ ratios about
5:1, the physical stability of the product may ~e adversely
affected.
In suitable circumstances other anionic detergents,
such as fatty alcohol sulfates, paraefin sulfonates, ol.efin
sulfonate~, monoglyceride .sulfates, sarcosinates and similarly
functioning detergents, preferably as the alkali metal, e.g.,
sodium salts, can be present, sometimes in partial replacement
of the previously mentioned synthetic organic detergents but
usually, if present, in addition to such detergents. Normally,
the supplementing detergents will be sulfated or sulfonated
products (usually as the sodium salts) and will contain long
chain (8 to 20 carbon atoms) linear or fatty alkyl groups. In
addition to any supplementing anionic synthetic organic deter-
gents, there also may be present nonionic and amphoteric mater-
ials, like the Neodols,~ sold by Shell Chemical Company,
which are condensation products of ethylene oxide and higher
fatty alcohols, e.g., Neodol~ 23-6.5, which is a condensation
product of a higher fatty alcohol of about 12 to 13 carbon
atoms with about 6.5 moles of ethylene oxide. Illustrations of
the various detergents and classes of detergents mentioned may
be found in the text Surface Active Agents, Vol. II, by
Schwartz, Perry and Berch (Interscience Publishers, 195~),
the descriptions of which are incorporated herein by reference.
~r
~2~'?~
62301-1384
The builder salt combination of this invention, which
has been found to satisfactorily improve the detergency of the
mixture of synthetic anionic organic detergents and produe the
desired pH in the liquid detergent and in the wash water, is a
mixture of sodium tripolyphosphate and sodium carbonate. The
builder salts are employed in the present compositions in
amounts generally oE from about 5 to 25%, by weight. For the
preferred builder salt combination, sodium tripolyphosphate is
present in amounts of from about 5 to 20~, preferably 10 to
16%, and sodium carbonate is present from about 1 to 10~, by
weight, preferably 3 to 7%, the weight ratio of tripolyphos-
phate to carbonate in the preferred bui1ders mixtures being
from about 2:1 to 6:1, and most preferably from about 2:1 to
4:1. As used herein, the term alkali metal "carbonates" or
"carbonate" is meant to include the carbonates, bicarbonates
and sesquicarbonates of such alkali metal.
For best processing, easier mixing and good end-use
properties it i5 preferred that the sodium tripolyphosphate be
low in con-tent of Phase I type tripolyphosphate. Thus, normal-
ly the content of Phase I type tripolyphosphate will be lessthan 30% of the tripolyphosphate employed. Although in some
instances incompletely neutralized tripolyphosphate may be
used, normally the phosphate employed may be considered as
being pentasodium tripolyphosphate, NasP301o. Of course, in
some instances, as when potassium salts of other materials are
present, ion interchange in an aqueous medium may result in
other salts than the sodium tripolyphosphate being present but
for the purpose of this specification it will be considered
that sodium tripolyphosphate, as the pentasodium salt, the
material which is normally charged to the mixer to make the
-- 10 --
.,
~ 2~
62301-1384
present liquid detergent, is the tripolyphosphate employed.
Other pre~erred builder salts which may be used in
place of sodium tripolyphosphate and sodium carbonate or in
addition thereto include a polyacetal carboxylate as herein
described and sodium nitrilotriacetate (NTA). of course, vari-
ous mixtures of the mentioned water soluble builder salts can
be utilized. Yet, the tripolyphosphate-carbonate mixture des-
cribed has been found to be most preferred, although the other
builders and mixtures thereof are also operative. Other build-
ers which may be employed as supplements, in addition to theproportions of the above mentioned builders, include other
phosphates, such as ~etrasodium pyrophosphate or tetrapotassium
pyrophosphate, sodium bicarbonate, sodium citrate, sodium glu-
conate, sodium silicate, and sodium sesquicarbonate. Among the
water insoluble builders that may be used are the zeolites,
such as Zeolite A, usually in the form of its crystalline hy-
drate, although amorphous zeolites may also be useful.
Polyacetal carboxylates are generally described in
U.S. Patents 4,144,226 and 4,315,092. U.S. Patent 4,146,495
describes detergent compositions containing polyacetal carboxy-
lates as builders.
The polyacetal carboxylates which are useful herein
as builders may be considered to be those described in U~S.
Patent 4,144,226 and may be made by the method mentioned there-
in. A typical such product will be of the formula
Rl - (cHo)n - R2
COOM
wherein M is selected ~rom the group consistiny of alkali
metal, ammonium, alkyl groups of 1 to 4 carbon atoms, tetra-
alkylammonium groups and alkanolamine groups, both of 1 to 4
-- 11 --
~97~
earbon atoms in the alkyls thereof, n avexages at least 4,
and Rl and R2 are any chemic~lly stable groups which stabilize
t~e polymer against rapi~ depolymerization in alkali~e
solution. Preferably the polyacetal carboxylate will be one
wherein M is alkali metal, e.g., sodium, n is from 50 to
200, ~1 is
C~3cH2O MOOC
~CO- or H3C-CO-
H3C MOOC
or a mixture thereof, R2 is
OCH2CH3
-CH
CH3
and n averages from 20 to 100, more pre~erably 30 to 80.
The calculated weight average molecular weights of the
polymers will normally be within the range of 2,000 to
70,000, preferably 3,500 to l0,000 and more preferably S,000
to 9,000, e.g., about 8,000.
A particularly preferred sodium polyacetal carboxylate
is supplied by Monsanto Company and is known as Builder U. It
has a calculated average molecular weight of about 8,000 and an
acti~e polymer content of about 80%.
Although the preferrPd polyacetal carboxylates have been
described above, it is to be understood that they may be wholly
or partially replaced by other such polyacetal carbo~ylates or
related organic builder salts described in the previously cited
patents on such compounds, processes for the manufacture thereof
and compositions in which they are employed. Also, the chain
terminating groups described in the various patents, especially
U.S. 4,144,226, may be utilized, providing ~hat they have the
-12-
4~
desired stabilizing properties, which allow the mentioned
builders to be depolymeri~ed in acidic media, facilitating
biodegradation thereof in waste streams, but maintain their
stability in alkaline media, such as washing solutions.
The bentonite employed herein is a colloidal clay
(aluminium silicate) containing montmorillonite. Swelling
bentonites are generally characterized as sodium bentonites,
i.e., bentonite wherein the predominant cation is sodium.
Among the sodium bentonite clays, those from Wyoming (generally
referred to as Western or Wyoming bentonite) are especially
preferred.
The swelling capacity of bentonite is generally associated
with its fabric softening properties. In water the s~elling
capacity of sodium bentonite is in the range of 3 to 20
milliliters/gram, preferably 7 to 15 ml/gram, and its viscosity,
at 6% concentration in water, is usually in the range of 3 to 30
centipoises, preferably 8 to 30 centipoises.
Preferred swelling bentonites are sold under the trademark
~I-JEL by Georgia Kaolin Co. These materials are the same as
bentonites which were formerly sold under the trademarks
MIN~AL COLLOID and Tl.~IXO-JEL. They are selectively mined and
beneficiated bentonites, and those considered to be most useful
are available as HI-JEL Nos. 1,2,3 etc., corresponding to
THIXO-JELs No's 1,2,3 and 4. Such materials have a maximum free
moisture content (before addition to the liquid medium) o~ 4% to
8% and specific gravities of about 2.6. The bentonite is pre~erably one which
will pass through a 200 mesh U.S. Sieve Series sieve, and most preferably
at least 90% of the particles will pass through a No. 325 sieve, so that the
equivalent diameter of the bentonite may be considered to be less
than 74 microns, and more preferably less than about 44 microns.
lZ~7~
62301--1384
Typical chemical analyses of some bentonites that are
useful for making the present liquid detergents show that they
contain from 64.8 to 73.0% of sio2, 14 to 18% of A12O3, 1.6 to
2.7% of MgO, 1.3 to 3.1% of CaO, 2.3 to 3.4% of Fe2O3, 0.8 to
2.8% of Na2O and 0.4 to 7O0% of K2O.
Although the western bentonites are preferred it is
also possible to utilize other bentonites, such as those which
may be made by treating Italian or similar bentonites contain-
ing relatively small proportions of exchangeable monovalent
metals (sodium and potassium) with alkaline materials, c~uch as
sodium carbonate, to increase the cation exchancJe capclcities o
such products. It is considered that the ~a2O content of the
bentonite should be at least about 0.5%, preferably at least 1%
and more preferably at least 2% so that the clay will be satis-
factorily swelling, with good softening and dispersing proper-
ties in aqueous suspension. Preferred swelling bentonites of
the types described above are sold under the trade names
Laviosa and Winkelmann, e.g., Laviosa AGB and Winkelmann G-13.
Other bentonites which are particularly useful for
the present liquid detergent compositions because of their
white or very light color include American Colloid Company's
Pol.arite KB 325, a Cali~ornia bentonite, and Georgia Kaolin's
GK 129, a Mexican ben-tonite.
The viscosity of the present liquid detergent is
normally in the range of about 1000 to 10,000 centipoises,
preferably 2000~7000 centipoises, but products of other suit-
able viscosities may also be useful. At the viscosities men-
tioned, the liquid detergent i6 pourable, stable, non-separa
ting and uniform. The pH of the liquid detergent suspension
- 14 -
,
~2~7~
62301-1384
usually in the range of 7 to 11.5, preferably 8 to 10.5,
appears to help to maintain product stability and pourability.
The following examples illustrate but do not limit
the invention. Unless otherwise indicated all parts are by
weight and temperatures are in C.
EXAMPLE_l
Component Percent
Pentasodium tripolyphosphate 11.0
10 Bentonite ~Georgia-Kaolin 129) 12~0
Sodium carbonate 2.0
Sodium sesquicarbonate 2.0
Sodium linear tridecylben~ene 8.0
sulfonate
AEOS(l)
Carboxymethyl cellulose (CMC) 0.2
Optical brightener 0.3
Perfume 0.4
EnPyme (Esperase 8.0L)(2) 1.0
Glycerine 3.0
Borax 2.5
Citric Acid ~.o
Water and adjuvants Balance
(1) Sodium alkyl polyethoxy sulfate wherein the alkyl is 12 to
15 carbon atoms and the polyethoxy is 3 ethoxy groups.
(2) "Esperase" sold by Novo Industries having an activity of
8.0 KNPU/gram.
, - 15 -
., ~ .,
79L~
The composition shown above was prepared by the following
procedure: 30.0 parts of deionized water at 40F are added to
a suitable mixing apparatus such as a vertical cylindrical tank
equipped with a stirrer. With the stirrer adjusted for medium
agitation, a mixture consisting of 2.0 parts anhydrous soda
ash, 2.0 parts sodium sesquicarbonate, and 0.2 parts sodium
carboxymethyl cellulose is incorporated into the water. The
stirrer speed is then increased to maximum agitation and a
mixture comprised of 11.0 parts pentasodium tripolyphosphate and
12.0 parts bentonite is slowly added to the mixing apparatus
over a period of 10-15 Mlnutes to Eorm an off-white suspension.
The agitation speed is then decreased to a slow/medium setting
while 8.64 parts of a high AI (about 55%) LTBS slurry is added.
Thereafter the optical brightener/color solution is added con-
sisting of 0.3 parts Tinopal L~'IS-X (CIBA-GEIGY), 0.99 parts
colorant, and 4.02 parts deionized water. Once a uniform blueish-
green colored solution is obtained, 0.4 parts of perfume are added
to the ~ixture under agitation. This is followed by the slow
addition of 3.0 parts glycerine and 2.5 parts borax as a two com-
ponent slurry. Stirring is continued until the mixture is uniorm
in appearance and then 2.0 parts of citric acid and ~.0 parts
water are slowly added. Agitation of the mixt~re is then reduced
while 10.95 parts of a mixed AI detergent base consisting of an LTBS
slurry (about 30% AI) and AEOS (about 27.5~ AI) is added to the
mixture. This is followed by the slow addition of l.O part
proteolytic enzyme with continous agitation until all materials
are completely dispersed or dissolved.
-16-
~2g7~
62301-1384
EXAMPLE 2
Enzyme-containing built liquid detergent compositions
A to G were formulated as set forth below in Table 1. The
percentages shown indicate weight percent. The arrows are
meant to indicate the extent to which Compositions ~ -to G are
identical to Composition A.
TABLE 1
Component A B C D E F G
Pentasodium 11.0
Tripolyphosphate
Bentonite (Georgia-Kaolin 129) 12.0
Sodium Carbonate 2.0
Sodium sesquicarbonate 2.0
Sodium Linear tridecyl- 8.0
benzene sulfonate
AEOS(l) 3.0
Optical brightener 0.3
(Tinopal LMS-X)
Perfume 0.4
CMC 0.2
Enzyme(2) 1.0 ~ ~ ~ / \ / \ / \ ~ \ /
Glycerine - 3.0 - 3.0 - - 3.0
Borax -- 2.5 2.5 - 2.5 2.5
Carboxylic acid compound - - - - 2.0 2.0 2.0
Water and adjuvants - Balance
(1) Sodium alkyl polyethoxy sulfa-te wherein the alkyl is 12 to
15 carbon atoms and the polyethoxy is 3 ethoxy groups.
(2) "Esperase" sold by Novo Industries having an activity of
8.0 KNPU/gm (Kilo Novo Protease units/gm).
17 -
~2g~
Tl~e enzyme ~ctivities of Compositions A to F were tested
after 7 days storage at 110F. The measured enzyme activity
~or each co~position after this period of storage is indicated
in Table 2 as a percent of the initial value. The ~arious
carboxylic acids and salts used in the general formulas of
Compositions A, B, C, D, E, and G are shown in Table 2 as well as the enzyme
activities corresponding to each composition.
TABLE 2
ENZY'~E STABILITY
Percent Active Enzyme
Co~position After 7 Days_at 110F
A (control) ND
B (with glycerine) ND
C (with borax) ND
D (with glycerine and borax) 50
CompositionE (with carboxylic acid
compound) wherein the carboxylic acid
` compound is:
: (1) Succinic acid - ND
(2) Malonic acid "
(3) Malic acid "
(4) Tartaric acid 1-
(5) Aspartic acid "
(6) Citric acid "
(7) Sodium tartrate "
(8~ Sodium citrate "
* ND = not detectable (below 10~ residual acti~ity)
112~74 ~
62301-1384
Composition G (with
glycerine/borax/carboxylic
acid compound) wherein thePercent Active Enzyme
carboxylic acid compound is:After 7 Days at llO~F
~1) Succinic acid 70
(2) Malonic acid 70
(3~ Malic acid 78
(~) Tartaric acid 73
(5) Aspartic acid 90
(6) Citric acid 74
(7) Sodium tartrate 66
(8) SoAium citrate 52
As evident from Table 2, Composition A, the control
composition, as well as Compositions B and C containing indivi-
dual stabilizers of glycerine and borax, respectively, mani-
fested almost no enzyme activity after the 7 day storage period
at 10~F. Since enzyme activities below 10% could not be pre-
cisely measured they are designated "ND". Composition D con-
taining glycerine/borax in the absence of a carboxylic acid
compound provided an improvement in enzyme stability relative
to Composition A, but about 50% of the enzyme was deactivated.
The various Compositions E containing a variety of carboxylic
acid compounds, as indicated, manifested absolutely no improve-
ment in enzyme stability relative to Composition A. However,
Compositions G ~ormulated in accordance wi-th the invention
demonstrate the unexpected and synergistic improvement in
enzyme stability which is achieved with the use of glycerine/-
borax in combination with a carboxylic acid compound in the
present liquid detergent compositions. It is noted that almost
every one of the compositions corresponding to Composition G
demonstrated a signiEicant improvement in enzyme activity
relative to Composition D (containing glycerine and bGrax).
~ 19 --
, ~ .
A comparison of the enzyme activities achieved with
Co~positions D (glycerine/borax) and various Compositions F
(borax/carboxylic acid compound) and G (formulated in accordance
~ith the invention) is set forth below in Table 3.
TABLE 3
Percent active Enzyme After
Composition 7 Days at 110F
D (Glyc~rine/borax) 50
F (Borax/malonic acid) 45
G (Glycerine/borax/malonic acid) 70
F (Borax/aspartic acId) 72
G (Glycerine/borax/aspartic acid) go
F (Borax/citric acid) 42
G (Glycerine/borax/citric acid) 74
As shown in Table 3, the various Compositions G containing
a three component stabilizer system in accordance with the
invention provided a synergistic improvement in enzyme
stability relative to Compositions D and F formulated in
accordance with the prior art.
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