Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
13~0~0~
STABLE. POURABLE AQUEOUS BLEACHING COMPOSITIONS COMPRISING
SOLID ORGANIC PEROXY ACID AND AT LEAST TWO POLYMERS
Field of the Invention
The invention relates to pourable bleaching compositions
comprising a solid, substantially water-insoluble organic peroxy
acid stably suspended in an aqueous medium. The bleaching
compositions of the current invention may be used alone or in
combination with other bleaches. Additionally, the current
bleaching compositions may be included as part of detergent,
bleaching, cleaning and/or disinfecting formulations.
Background of the Invention
Bleaching compositions comprising a .solid, substantially
water-insoluble organic peroxy acid stably suspended in an
aqueous medium are generally known from British Patent
Specification 1 535~80~. It claims fabric bleaching compositions
having a viscosity from 200 to 100,000 cp. and a non-alkaline pH,
the compositions comprising an aqueous carrier, 1-40 weight %
particulate organic substantially water-insoluble peroxygen
compound and a thickening agent. Specifically mentioned
thickening agents are inorganic thickeners, such as clays, and
organic thickeners, such as water-soluble gums, mucilaginous
materials, starches, polyacrylamides and carboxylpolymethylene.
In particular, British Patent Specification 1 535 804 discloses
the use of cellulose derivatives such as carboxymethyl
celluloses, hydroxypropyl cellulose and methyl hydroxybutyl
cellulose, hydrolyzed proteins such as hydrolyzed keratins,
glutens, polyvinyl alcohol and polyvinylpyrrolidone, and natural
gums such as gum arabic, carrageen and various agars.
Further, the non-prepubl shed European Patent
/JCC-ff~ si,~ ) ~e~f~ h~ " ~
~plioation No. 283 792/discloses storagé-stable, pourable
aqueous bleach suspensions having a pH value in the range of 1 to
6 and containing (a) particulate, water-insoluble peroxy-
-- 13'1q308
carboxylic acid-(e.g., diperoxydodecanedioic acid), (b) xanthan
gum or agars, (c) hydratable neutral salt (e.g., Na2S04), (d)
optionally an acid for pH regulation (e.g., H2S04), and (e)
aqueous liquid.
It is known to be advantageous to use liquid bleaching
compositions rather than solid bleaching compositions in
automatic clothes washers and dryers. Among those advantages is
that with liquid bleaching compositions there is no need for
cost-increasing shaping steps, such as granulating and drying.
Additionally, liquid bleaching compositions are more easily
dispersed in wash liquor or in an automatic clothes dryer so the
fabrics are more rapidly and evenly bleached. Uneven bleaching
can damage fabric as a result of localized high concentrations of
bleaching agent.
p~bl,~h~ rr~ G
As disclosed in European Paten~ Application 176 124~ the
bleaching compositions of GB 1 535 804, at least as far as they
are pourable, have ~he disadvantage that they are not physically
stable. As shown by Composition 7 in EP 176 124, after prolonged
~ ~.
storage, pourable bleaching compositions of GB 1 535 804 undergo
phase separation, producing a thick bottom layer which is
difficult to disperse or homogenize. Consequently, the
aforementioned advantage of even fabric distribution may be
partly eliminated.
Further it should be mentioned that GB 1 535 804 does
not disclose or suggest the use of more than one thickening agent
in a single fabric bleaching composition. Indeed, it is clear
from Example III of GB 1 535 804 that the cellulose derivatives
tested as thickening agents were tested in individual, separate
bleach compositions. Additionally, the bleach composition of
Example III of GB 1 535 804 is a "thick, semi-gelatinous
composition" (see page 11, lines 32-35 of GB 1 535 804) rather
than a pourable composition of the present invention.
~-' 13'10~0~
It should be noted that United States Patent 4 232 141
(NL 707 916) discloses, inter alia, grinding coarser particles of
a polymerization initiator in an aqueous medium containing a
dispersing agent to form an aqueous dispersion of the polymeri-
zation initiator. The polymerization initiator may be, inter
alia, a peroxy dicarbonate or a benzoyl peroxide. Claim 9 claims
that the dispersing agent may be polyvinyl alcohol, cellulose
ether, gelatine or a mixture thereof. However, only single
dispersing agents (either polyvinyl alcohol or methyl cellulose)
are used in the working examples of US 4 232 141 to form
polymerization initiator dispersions. These dispersions were
then added to vinyl chloride polymerization suspensions to form
polyvinyl chloride. Some vinyl chloride polymerization
suspensions of the examples of US 4 232 141 contain a mixture of
polyvinyl alcohol and methyl cellulose. However, as demonstrated
herein below, an aqueous suspension acceptable under bleaching
conditions (pourability, physical stability and chemical
stability) and prepared as suggested by US 4 232 141 is not
physically stable.
Further, the product brochure "Xanthan Gum/Keltrol/
Kelzan/a natural biopolysaccharide for scientific water control"
(printed by Kelco, a division of Merck & Co., Inc., 1976, Second
Edition) teaches at pages 8 and 9 that "[x]anthan gum is
compatible with most commercially available thickeners, both
synthetic and natural". However, the brochure also teaches that
"[t]he use of xanthan gum with cellulose derivatives is generally
not recommended". Thus, the brochure does not mention the use of
xanthan gum with polyvinyl alcohol and specifically teaches
against the use of xanthan gum with cellulose derivatives.
It has been surprisingly found that a pourable bleaching
composition may be formed comprising a solid, substantially
water-insoluble organic peroxy acid stably suspended in an
aqueous medium, the aqueous medium also comprising at least two
polymers wherein the first polymer is one or more natural gums,
"- l3~n~ns
such as xanthan gum, and the second polymer is selected from the
group consisting of polyvinyl alcohol ("PVA"), cellulose
derivatives and mixtures thereof. The term "mixtures thereof"
includes mixtures of only cellulose derivatives as well as
mixtures of one or more cellulose derivatives with PVA. The
composition may also comprise an electrolyte, such as Na2S04.
To be useful, the current bleaching compositions should
be conveniently pourable and relatively stable, both chemically
and physically.
The bleaching compositions of the current invention are
conveniently pourable when they may be poured relatively easily
and smoothly from small containers (e.g. household size, approx.
0.1 to 2.0 liters) and large containers (e.g. industrial and bulk
transport size). Quantifying the "pourability" of the current
bleaching compositions is difficult since the compositions are
non-Newtonian fluids. With non-Newtonian fluids the shear stress
(an indication of a fluid's resistance to flow and therefore its
pourability) varies with the shear rate. For example, some
non-Newtonian fluids may have very little initial resistance to
flow and pour easily and smoothly. The preferred current
bleaching compositions have such flow behavior for both large and
small containers. However, other non-Newtonian fluids may have
substantial initial resistance to flow and then pour easily and
smoothly, as with tomato ketchup. Non-Newtonian fluids may also
be gel-like and offer both initial and continued resistance to
flow. Initial resistance to flow may be referred to as a fluid's
"yield value". Generally, bleaching compositions having little
or no yield value are preferred; that is, they are conveniently
pourable. As one advantage of the current two-polymer bleaching
composition, it is possible to prepare stable aqueous suspensions
of substantially water-insoluble organic peroxy acid having
little yield value. Although viscosity measurements do not
precisely measure either the pourability or the yield value of
non-Newtonian fluids, viscosity measurements do indicate the
13 ~1030.~
relative thickness and thus the relative pourability of
non-Newtonian fluids. The Brookfield method is one well-known
way to measure the viscosity of a fluid. However, the Brookfield
method does not measure shear rate. Since the viscosity of a
non-Newtonian fluid is shear rate-dependent, Brookfield viscosity
provides only a relative indication of the viscosity of a fluid.
In general, though non-limiting, bleaching compositions of the
current invention are "pourable" if the Brookfield viscosity is
below about 2000 mPa.s (Brookfield, 20 r.p.m.) and preferably
below about 1500 mPa.s (Brookfield, 20 r.p.m.).
, .
On the other hand, with the appropriate equipment (such
as a Haake Rotorisco RV 100), it is possible to measure the shear
stress and the shear rate of a non-Newtonian fluid. Such data
may be used to predict the yield values of such fluids. Further,
viscosity may be calculated from the stress and shear rate
data. A plot of viscosity versus shear rate data produces a
"rheogram". Since the viscosity of a non-Newtonian fluid is
shear rate-dependent, a rheogram provides a more accurate
viscosity profile and therefore a better indication of the
"pourability" of non-Newtonian fluids. The above-referenced
product brochure "Xanthan Gum/Keltrol/Kelzan/a natural
biopolysaccharide for scientific water control" provides the
shear rate values acting on solutions of xanthan gum as they are
poured from a bottle over the shear rate range of about 10-100
s-l (see page 28).
The bleaching compositions of the current invention are
chemically stable when the activity of the organic peroxy acid
undergoes insignificant, and preferably no, reduction over a
reasonable storage time. One measure of the potential bleaching
activity of an organic peroxy acid, or a composition containing
an organic peroxy acid, is the active oxygen (A.O.) content.
However, "active oxygen" is affected by the presence of H202
as well as peroxy acid. Therefore, a more accurate indication of
chemical stability after storage is "residual peroxy acid" which
is active oxygen minus H202.
i340308
.~ .
--6--
The bleaching compositions of the current application
are physically stable when the compositions undergo
insignificant, and preferably no, phase separation during a
reasonable storage time.
SummarY of the Invention
The present invention relates to bleaching compositions
comprising a solid, substantially water-insoluble organic
peroxy acid stably suspended in an aqueous medium, said
aqueous medium comprised of at least two polymers wherein
the first polymer is one or more natural gums, preferably
xanthan gum, and the second polymer is selected from the
group consisting of polyvinyl alcohol, cellulose derivatives
and mixtures thereof. The bleaching composition may
additionally be comprised of an electrolyte, such as Na2SO4.
Brief DescriPtion of the Drawinq
Fig. 1 is a rheogram of the Test Suspensions lB and lC
of Example 1 and the suspensions of Example 2 and Table 2.
Detailed DescriPtion of the Invention
The solid, substantially water-insoluble organic peroxy
acids which may be used in the bleaching compositions of the
current invention are generally known in the art. As non-
limiting examples, the solid organic peroxy acids disclosed
in European Patent Applications 160 342, 176 124 and 267 175
respectively published on November 6, 1985, April 2, 1986
and May 1988, US Patents 4 681 592 and 4 634 551 and GB
Patent Specification 1 535 804 may be used. The most
preferred organic peroxy acids which may be used in the
compositions of the current invention are (1) diperoxy
acids, such as l,12-diperoxydodecanedioic acid ("DPDA"),
diperazelaic acid and 1,13-diperoxytridecanedioic acid, (2)
peroxy acids which have a polar amide link in the
X
_7_ 13~03~
hydrocarbon chain, such as N-decanoyl-6-aminoperoxyhexanoic
acid,
N-dodecanoyl-6-aminoperoxyhexanoic acid, 4-nonylamino-4-
oxoperoxybutyric acid and 6-nonylamino-6-oxoperoxyhexanoic
acid, and (3) alkyl sulphonyl peroxycarboxylic acids, such
as heptyl sulphonyl perpropionic acid, octyl sulphonyl
perpropionic acid, nonyl sulphonyl perpropionic acid and
decyl sulphonyl perpropionic acid. Methods for preparing
such preferred organic peroxy acids are known in the art and
in particular from the above cited references. Optionally,
the solid organic peroxy acid may be coated with a water-
impermeable material, such as the fatty acids lauric acid,
myristric acid and mixtures thereof, as known from European
Patent Application 254 331 published on January 27, 1988.
The amount of organic peroxy acid in the current bleaching
formulations depends on criteria such as the active oxygen
("A.O.") content of the peroxy acid and the intended use of
the bleaching composition. The preferred amount of peroxy
acid is that which will provide effective washing,
bleaching, cleaning and/or disinfecting in a diluted use
liquor. Generally, though non-limiting, the current
bleaching compositions have a peroxy acid concentration
which will provide an A.O. content of between about 1 and
about 200 ppm, and preferably between about 2 and about 100
ppm in a typical diuted liquor for use in washing,
bleaching, cleaning and/or disinfecting.
The first polymer is one or more natural gums. As non-
limiting examples, the natural gums may be xanthan gum, guar
gum, gum arabic, carrageen and agars obtained from seaweed.
Xanthan gum is the preferred natural gum. The amount of
natural gum desired in the current bleaching formulations is
the amount which is effective to provide a physically and
chemically stable, pourable aqueous formulation. Generally,
though non-limiting, natural gum is present as about 0.1 to
about 1 wt.% of the bleaching composition.
-7a- 1340~~~
The second polymer is selected from the group
consisting of polyvinyl alcohol, one or more cellulose
derivatives and mixtures thereof. A group of cellulose
derivatives particularly
1~ 40 3~8
useful are cellulose ethers. Cellulose ethers are known from,
for example, Ullmann's Encyclopedia of Industrial Chemistry,
Fifth Edition, Vol. A5, pages 461-487. Of particular use in the
current bleaching compositions are methyl cellulose, methyl
hydroxypropyl cellulose, methyl hydroxybutyl cellulose,
hydroxyethyl cellulose and carboxymethyl cellulose. The amount
of second polymer incorporated in the current bleaching
formulations is the amount which will provide a physically and
chemically stable, pourable aqueous bleaching composition.
Generally, though non-limiting, the second polymer is present as
about 0.02 to about 2 wt.% of the bleaching composition.
An electrolyte may also be present in the aqueous medium
to help provide a useful, pourable bleaching composition. The
electrolyte may result from the residual acid present in the
peroxy acid as a result of the peroxidation reaction. The
electrolyte may also be added deliberately to enhance the
physical stability of the current suspensions and increase their
safe handling (See European Patent Application 176 124).
Examples of suitable electrolytes are Na2S04, K2S04,
MgS04, Al2(S04)3, NaN03 and borate salts. The amount
of electrolyte present depends, inter alia, on the peroxy acid
and the polymers employed and on the intended use of the
suspension. However, in general, though non-limiting, the
electrolyte may be up to about 30 wt.% of the composition.
Optionally, the current bleaching compositions may also
comprise antifreezing agents, such as glycol.
The bleaching compositions of the current invention are
further illustrated by the following non-limiting examples.
Example 1 (Comparative Example)
This example illustrates the problems presented by
aqueous organic peroxy acid suspensions which contain no polymer
. . , . .. . ~ ....
Q 8
or which contain only one water-soluble polymer. Test
suspensions of 500 grams were prepared by mixing 274 grams
organic peroxy acid (1,12-diperoxydodecandioic acid ("DPDA") in
wet filter cake form, having an active oxygen (AØ) content of
5.47%) with a solution of 15 grams Na2S04 and 1 gram test
polymer (if present) based on active material in 210 grams
water. This produced test suspensions having an active oxygen
content of 3.0~. The viscosity of each test suspension was
measured (Brookfield RV, 20 r.p.m.) and the physical stability
(in terms of phase separation) was monitored during an 8 week
20~C storage period. The results are contained in Table 1.
Table 1
Test Water-soluble Viscosity Phase
Suspension Polymer (mPa.s) Separation
lA None 2400 None
lB Xanthan gum 1700 Small amount
~ (Rhodigel~ 23
from Rhone Poulenc)
lC Hydroxyethyl 50 Large amount
cellulose (Natrosol2
250 L from Hercules)
As shown in the results in Table 1, even though the
addition of the water-soluble polymer hydroxyethyl cellulose
substantially reduces the test suspension viscosity, making it
conveniently pourable, the phase separation is unacceptable.
The addition of xanthan gum alone to the test suspension reduces
viscosity, but not enough to provide acceptable pourability.
Also, Test Suspension lB is not physically stable as indicated
by the phase separation.
-
!
-lO- 1340308
Example 2
To have use as a bleaching composition, the suspensions
of the current invention must be chemically stable as well as
pourable and physically stable. That is, the bleaching
compositions of the current invention must retain their ability
to bleach while they are being stored prior to use. The chemical
stability of a peroxy acid is indicated by the retention of
active oxygen (A.O.). However, active oxygen is affected by the
presence of H2O2 as well as peroxy acid (such as DPDA).
H2O2 is formed by the decay reactions of peroxy acids.
Therefore, a more accurate indication of chemical stability after
storage is the "residual peroxy acid", o~ in this case, "residual
DPDA". "Residual DPDA" is the active oxygen content (A.O.) minus
H2O2 formed by the decay of the peroxyacid. The H2O2
content was determined by extraction with a mixture of diethyl
ether and water, separation of the water layer, addition of
Ti(IV) reagent and spectrophotometric measurement of the yellow
complex formed.
Two 500 gram test suspensions were independently
prepared by mixing 274 grams DPDA filter cake (A.O. - 5.47%) in
about 200 grams of water. The first suspension was completed by
adding 15 grams Na2SO4 and 0.25 gram Dequest~ 2010 (a
sequestering agent available from Monsanto). The second
.4 .. ~ ~
suspension was completed by adding 15 grams Na2SO4, 0.25
grams Dequest 2010, 1 gram hydroxyethyl cellulose (Natrosol
250 L) and 1 gram xanthan gum (Rhodigel~23). The initial active
oxygen content and viscosity of each suspension were measured.
Each suspension was divided in half. One half of each suspension
was stored for 8 weeks at 20~C and the other half stored for 8
weeks at 30~C. The chemical stability (active oxygen loss and
residual DPDA), the rheology (viscosity) and the physical
stability (phase separation) data are in Table 2 below.
/c ~ r~
1340308
Table 2
Suspension With
Suspension Xanthan Gum and
Without Polymers Hydroxyethyl Cellulose
(Suspension 2A) (Suspension 2B)
Loss in Active Oxygen < 1% < 1%
(8 weeks at 30 C)
Residual DPDA
After 8 weeks at 20 C 99% 98~
After 8 weeks at 30~C 96% 95%
Phase Separation
After 8 weeks at 20 C none none
After 8 weeks at 30 C none none
Viscosity (Brookfield
"
RV, lO rpm) in mPa.s
Initially 9500 650
After 8 weeks at 20 C 9800 580
Surprisingly, the suspensions of the current invention
were conveniently pourable as well as being chemically and
physically stable over the 8 week test period.
In order to compare and predict the rheological
behavior ("pourability") of known compositions and compositions
of the current invention, a plot of viscosity vs. shear rate
("rheogram") was generated for Test Suspensions lB and lC of
Example 1 and for the suspensions of Example 2. The shear
stress was recorded versus the shear rate applied with a Haake
Rotovisco RV 100 at 20~. The calculated viscosity values are
plotted versus the shear rate in Fig. 1. Suspensions which
13~0308
follow the curve of Suspension lB are not easily pourable as
demonstrated by laboratory attempts to pour them without shaking
the contents of the container. (Note that such lack of
pourability was also indicated by the Brookfield viscosity
measurement of Suspension lB as reported at Table 1.) However,
suspensions which follow the curve of Suspension 2B are
pourable. Liquid detergents currently available in Western
Europe (therefore having commercially acceptable pourability)
follow the curve of Suspension 2B and are of lower viscosity than
Suspension lB. As discussed in Example 1, Suspension lC is
pourable but not physically stable.
Additionally, from plots of shear stress versus shear
rate, the yield value of Suspension 2A was found to be about 200
Pa while that of Suspension 2B was found to be about 15 Pa. For
suspensions of the current invention, yield values between about
5 and about 20 Pa provide the most desirable "pourability"
behavior.
Exam~le 3 (Comparative Example)
A bleaching composition comprised of components
suggested by the disclosure in US Patent 4 232 141 was prepared
as a comparative example. A test suspension was prepared by
mixing 326.1 grams DPDA wet filter cake (AØ - 5.22%) with 193.9
grams of an aqueous solution of 0.25 gram Dequest 2010, 1.0 gram
PVA (Gohsenol5 KP-08, 75% hydrolyzed, available from Nippon
Gohsei) and 1.0 gram hydroxyethyl cellulose (Natrosol 250 L
available from Hercules). This produced a test suspension having
an active oxygen content of 3.3%. Sodium sulfate was omitted
from the composition since PVA precipitated from solution in the
presence of Na2SO4 prior to the addition of DPDA. The
viscosity of the test suspension was 89 mPa.s (Brookfield LVT, 30
r.p.m.). After 8 weeks storage at 20~C, 160 ml of water
separated from the test suspension.
1340308
... .
Example 4
A bleaching composition was prepared in accordance with
the composition of Example 3 modified by the addition of 1.0 gram
xanthan gum, placing the test suspension of this Example 4 within
the scope of the current invention. The viscosity of the test
suspension was 938 mPa.s (Brookfield LTV, 30 r.p.m.). After 8
weeks storage at 20~C, only an insignificant 4 ml of water
separated from the test suspension. The composition was
conveniently pourable.
Example 5
As disclosed in European Patent Application 254 331,
organic peroxy acids may be prepared in such a manner that the
resulting organic peroxy acid also comprises a water-impermeable
material, such as fatty acid. The fatty acid may, among other
things, increase the safe handling and use of organic peroxy
acids.
Test suspensions using DPDA with lauric acid (a fatty
acid) were prepared by mixing 206 grams DPDA coated with lauric
acid (wet filter cake, AØ - 6.07%) aqueous solutions containing
varying amounts PVA or PVA and xanthan gum as set forth in Table
3 to form 500 gram aqueous suspensions. The lauric acid-coated
DPDA was prepared substantially in accordance with the method of
European Patent Application 254 331 by heating and stirring a
suspension of DPDA at 50~C, adding lauric acid in a weight ratio
of 3:1 DPDA to lauric acid, stirring for 10 minutes, cooling and
separating the DPDA and lauric acid combination from water on a
filter.
Again, the viscosity of each test suspension was
measured (Brookfield RV at 20 r.p.m., except Test Suspension 3D
which was measured at Brookfield LV at 60 r.p.m.) and the
physical stability was monitored during an 8 week period at
'- 1341~308
20~C. The data are reported in Table 3.
Test Suspension 3A does not contain a water-soluble
polymer. It does not separate over the 8 week period but it is
not conveniently pourable. Test Suspensions 3B, 3C and 3D
contain the water-soluble polymer PVA (as suggested by US Patent
4 232 141). They are conveniently pourable but have unacceptable
phase separation. Test Suspension 3E, containing both xanthan
gum and PVA according to the present invention, shows no phase
separation, is as chemically stable as Test Suspension 3A and is
conveniently pourable. Thus, the current bleaching compositions
are suitable for use with organic peroxy acids which also
comprise a water-impermeable material. ~~~
Table 3
Test Water-soluble Viscosity H20 Separation
Suspension Polymer(s) ~mPa.s)After 8 Weeks
3A None 7600 0
3B 0.5 g PVA 905 38
(Gohsenol KP-08)
3C 1.0 g PVA 421 42
(Gohsenol KP-08)
3D 2.0 g PVA 43 139
(Gohsenol KP-08)
3E 1.0 g PVA (Gohsenol1360 0
KP-08) and 1.0 g
xanthan gum (Rhodigel)
Example 6
For some purposes (such as bulk transportation), it is
... . . . ... ..
134~30~
;
desirsble to produce aqueous, pourable suspensions having
relatively high peroxy acid concentration and/or active oxygen
content. It has been surprisingly found that the bleaching
compositions of the current invention are capable of containing
substantially increased amount of organic peroxy acid on a weight
percent basis.
For example, currently known aqueous suspensions of the
organic peroxy acid DPDA are capable of a maximum of about 32
wt.% DPDA and have an acti~e oxygen content of about 3.5%. In
the case of aqueous suspensions of DPDA in combination with a
water-impermeable material, such as a fatty acid (for example,
lauric acid), the active oxygen content may be reduced to about
2.5%. Surprisingly, aqueous suspensions have been prepared using
the polymer system of the current invention to produce bleaching
compositions with substantially increased DPDA (with and without
lauric acid) concentration and substantially increased active
oxygen content. The details of these compositions are contained
in Table 4.
1340~08
-16-
Table 4
Suspension of
Suspension of DPDA-Lauric
DPDA Particles Acid Particles
1. Composition (wt.%)
DPDA 43.5
DPDA-Lauric Acid (3:1) - 40.7
Nydroxyethyl 0.3
cellulose (Natrosol 250 L)
Polyvinyl Alcohol - 0.4
(Gohsenol KP-08)
Xanthan Gum (Rhodigel) 0.1 0.2
Dequest 2010 0.05 0.05
2. Initial A.O. content 11.5 8.6
of DPDA (%)
3. Initial A.O. content of 5.0 3.5
~Suspension
4. Chemical Stability
8 weeks, 20~C 96 98
(Residual DPDA as % of
Initial DPDA)
8 weeks, 30~C 95 97
(Residual DPDA as % of
Initial DPDA)
5. Phase Stability
8 weeks, 30 C No Phase No Phase
Separation Separation
13~0~,08
Example 7 ~ .
Suspensions having relatively high peroxy acid
concentrations (e.g., above about 20 wt.% for peroxyacids such
as DPDA) are preferred for industrial purposes, such as bulk
transportation and handling. However, relatively low peroxy acid
concentrations (e.g., about 5-10 wt.% for peroxyacids such as
DPDA for U.S. consumers) are desirable for household use.
Therefore, it is most preferable that the previously described
pourable, storage-stable concentrated suspensions can be diluted
to form pourable, storage-stable dilute suspensions.
As provided in Table 5, two suspensions having
relatively high peroxy acid concentrations (27 wt.%) were
prepared. Suspension 5A is a comparative example containing
peroxy acid and sodium sulfate. Suspension 5B is a two polymer
formulation within the current invention. Comparative
Suspension 5A was used to prepare 500 ml dilute Comparative
Suspension 5C. Suspension 5B was used to prepare 500 ml dilute
Suspens,ion 5D according to the current invention. As reported
in Table 5, dilute Suspension 5D is physically and chemically
stable over a 4 week period while Suspension 5C separates after
3 weeks at 40~C. Chemical stability is reported in terms of
"Residual DPDAn. "Residual DPDA" was determined by the method
described in Example 2, above.
13~0~0~
~ ~ Table 5
Phase Chemical
Stablllty Stability
(Separate (Residual
Water- Uater Phase DPDA After
Test SolubleWt.% After 4 4 weeks,
Suspension* ~ Polymer(s) DPDA weeks. 40 C~ 40~C)
5A - None 27 Not Not
Determined Determined
5B - 0.2 wt.% 27 ~~ Not Not
xanthan gum Determined Determined
0.2 wt.%
hydroxyethyl
cellulose
5C 3 0.5 wt.% 6 50 ml 90%
xanthan gum
5D 3 0.05 wt.~ 6 0 ml 90%
xanthan gum
0.05 wt.%
hydroxyethyl
cellulose
* All Test Suspensions contain 3 wt.% sodium sulfate. Test
suspensions 5C and 5D contain 0.5 wt.% Dequest~ 2010 (a
sequestering agent) and 3 wt.% a~id.
Example 8
This Example 8 demonstrates, inter alia, the effect of
temperature on suspensions of the current invention.
Temperature effects are particularly important in that
1~0308
industrial proaessing and transportation is likely to occur at
lower temperatures (e.g., about 10~C-30~C) while consumer storage
and usage is likely to occur at higher temperatures (e.g., about
20~-40~C).
Test suspensions identical to those of Example 2 were
prepared. Suspension 8A is identical to Suspension 2A.
Suspension 8B is identical to Suspension 2B. Portions of the
suspensions were stored for 8 weeks at 20~C, 30~C and 40~C then
tested for chemical stability (residual DPDA), phase stability
and rheological stability ("pourability"). Additionally, these
characteristics were also monitored after 4 weeks for suspensions
stored at 40~C. The results are provided in Table 6. It should
be noted that "pourability" was determined by pouring (or
attempting to pour) each suspension from a 500 ml container.
Suspensions giving a streaming behsvior similar to that of
commercially available heavy duty detergents were "pourable".
1340~08
-20-
Table 6
Suspension 8A Suspension 8B
(Without Polymers) (With Polymers)
Chemical Stability
(Residual DPDA~
a. 8 weeks/20~C 99% 98%
b. 8 weeks/30~C 96% 95%
c. 4 weeks/40~C 93% 92%
d. 8 weeks/40~C 84% 79%
Phase Stability
a. 8 weeks/20'C No Phase Separation No Phase Separation
b. 8 weeks/30 C " " " n
c. 4 weeks/40~C " " " " " "
d. 8 weeks/40 C n
Rheological Stability
a. 8 weeks/20~C Not Pourable Pourable
b. 8 weeks/30~C " " "
c. 4 weeks/40 C " " "
d. 8 weeks/40~C " " Pourable (but
thickening)
Analysis of the data provided in Table 6 indicates that
the suspensions of the current invention are chemically,
physically and rheologically stable over time and temperature.
Additionally, the chemical stability and physical stability of
the suspension of the current invention (Suspension 8B) are
equal, or substantially equal, to those of Suspension 8A while
Suspension 8B has the advantage of rheological superiority and
stability.
~ ~, . . . . .. . ... . . .
