Note: Descriptions are shown in the official language in which they were submitted.
CA 02318491 2000-07-07
WO 99/36503 PCT/US98/00567
GRANULAR COMPOSITIONS HAVING IMPROVED DISSOLUTION
FIELD OF THE INVENTION
The present invention relates to improving the dissolution of a granular
detergent
composition, especially in cold temperature laundering solutions (i.e., less
than about
30°C). More particularly, the detergent composition contains particles
having optimally
selected physical properties, such as particle size, particle density and
concentration of
detergent ingredients, for achieving improved dissolution performance.
BACKGROUND OF THE INVENTION
Recently, there has been considerable interest within the detergent industry
for
laundry detergents which are "compact" and therefore, have low dosage volumes.
To
facilitate production of these so-called low dosage detergents, many attempts
have been
made to produce high bulls density detergents, for example with a density of
600 g/1 or
higher. These low dosage detergents are currently in high demand as they
conserve
resources and can be sold in small packages which are more convenient for
consumers.
Unfortunately, such low dosage or "compact" detergent products experience
dissolution
problems, especially in cold temperature laundering solutions (i.e., less than
about 30°C).
More specifically, poor dissolution results in the formation of "clumps" which
appear as
solid white masses remaining in the washing machine or on the laundered
clothes after
conventional washing cycles. These "clumps" are especially prevalent under
cold
temperature washing conditions and/or when the order of addition to the
washing machine
is laundry detergent first, clothes second and water last (commonly known as
the
"Reverse Order Of Addition" or "ROOA"). Similarly, this clumping phenomenon
can
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2
contribute to the incomplete dispensing of detergent in washing machines
equipped with
dispenser drawers or in other dispensing devices, such as a granulet. In this
case, the
undesired result is undissolved detergent residue in the dispensing device.
It has been found that the cause of the aforementioned dissolution problem is
associated with the "bridging" of a "gel-like" substance between surfactant-
containing
particles to form undesirable "clumps." The gel-like substance responsible for
the
undesirable "bridging" of particles into "clumps" originates from the partial
dissolution of
surfactant in the aqueous laundering solutions, wherein such partial
dissolution causes the
formation of a highly viscous surfactant phase or paste which binds or
otherwise
"bridges" other surfactant-containing particles together into "clumps." This
undesirable
dissolution phenomena is commonly referred to as "lump-gel" formation. In
addition to
the viscous surfactant "bridging" effect, inorganic salts have a tendency to
hydrate which
can also cause "bridging" of particles which linked together via hydration. In
particular,
inorganic salts hydrate with one another to form a cage structure which
exhibits poor
dissolution and ultimately ends up as a "clump" after the washing cycle. It
would
therefore be desirable to have a detergent composition which does not
experience the
dissolution problems identified above so as to result in improved cleaning
performance.
The prior art is replete with disclosures addressing the dissolution problems
associated with granular detergent compositions. For example, the prior art
suggests
limiting the use and manner of inorganic salts which can cause clumps via the
"bridging"
of hydrated salts during the laundering cycle. Specific ratios of selected
inorganic salts
are contemplated so as to minimize dissolution problems. Such a solution,
however,
constricts the formulation and process flexibility which are necessary for
current
commercialization of large-scale detergent products. Various other mechanisms
have
been suggested by the prior art, all of which involve formulation alteration,
and thereby
reduce formulation flexibility. As a consequence, it would therefore be
desirable to have
a detergent composition having improved dissolution without significantly
inhibiting
formulation flexibility.
Accordingly, despite the disclosures in the prior art discussed previously, it
would
be desirable to have a detergent composition which exhibits improved cleaning
CA 02318491 2004-02-03
performance. Also, it would be desirable to have such a detergent composition
which
exhibits such improved dissolution without significantly inhibiting
formulation
flexibility.
SUMMARY OF THE INVENTION
The invention meets the needs above by providing a detergent composition which
has improved dissolution in laundering solutions, especially in solutions kept
at cold
temperatures (i.e., less than about 30°C). A combination of optimally
selected physical
properties of various particulate detergent ingredients in a detergent
composition is used
to achieve improved dissolution performance. Specifically, the detergent
composition
comprises from about 1% to about 50%, based on the total number of discrete
particles
in the composition, of substantially "sticky particles" with certain
composition, size and
density specifications. The substantially sticky particles contain at least
about 15%,
preferably at least about 45%, by weight of the sticky particles, of a
"substantially sticky
surfactant." In addition, the substantially sticky particles have a geometric
mean particle
diameter size of from about 300 microns to about 700 microns with a geometric
standard
deviation of less than about 1.8, and a bulk density of at least about 450
g/1.
Additionally, the composition includes at least about 35%, based on the total
number of
discrete particles in the admixture composition, of substantially non-sticky
particles
having a geometric mean particle diameter size of from about 200 microns to
about 500
microns with a geometric standard deviation of greater than about 1.2 and a
bulk density
of less than about 850 g/1. The non-sticky particles contain less than about
1% by weight
of a sticky surfactant. The substantially non-sticky particles may include
inorganic
fillers, builders, "substantially non-sticky surfactants" and other
ingredients. Typically,
the non-sticky particles will have a substantially low to nil (i.e., less than
about 10% on a
weight basis) concentration of sticky surfactants. The total amount of
surfactants,
including both sticky and non-sticky surfactants, in the composition is a
least about 15%
by weight of the composition.
With the aforementioned optimally selected particulate concentrations,
respective
particle densities, particle sizes and particle size ranges as measured by
geometric mean
and geometric standard deviation statistics, the composition unexpectedly
exhibits
superior dispersion and dissolution in cold temperature laundering solutions.
A method
of laundering clothes comprising the steps of contacting soiled clothes with
an effective
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4
amount of a detergent composition according to compositions described herein
in an
aqueous washing solution is also provided.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention provides a detergent composition which exhibits improved
dispersion and dissolution in aqueous laundering solutions. It has been found
that by
optimally selecting physical properties of various particles contained in
granular detergent
compositions, the dissolution can be improved. As mentioned previously,
typical
detergent formulations that dissolve in aqueous laundering solutions form
highly viscous
surfactant phase or paste which binds or otherwise "bridges" other surfactant-
containing
particles together into "clumps" ultimately causing "lump-gel" formation.
As used herein, the phrase "discrete particles" means individual particles,
agglomerates or granules which can be identified via a scanning electron
microscope as
discrete units of mass. For each type of particle component in an admixture,
the discrete
particles of that type have the same or substantially similar composition
regardless of
whether the particles are in contact with other particles. For agglomerated
components,
the agglomerates themselves are considered as discrete particles and each
discrete particle
may be comprised of a composite of smaller primary particles and binder
compositions.
As used herein; the phrase "geometric mean particle diameter" means the
geometric mass
average diameter of a set of discrete particles as measured by any standard
mass-based
particle size measurement technique, such as dry sieving. As used herein, the
phrase
"geometric standard deviation" of a particle size distribution means the
geometric breadth
of the best-fitted log-normal function to the above-mentioned particle size
data.
As used herein, the phrase "builder" means any inorganic material having
"builder" performance in the detergency context, and specifically, organic or
inorganic
material capable of removing water hardness from washing solutions. As used
herein, the
term "bulk density" refers to the uncompressed, untapped powder bulk density,
as
measured by pouring an excess of powder sample through a funnel into a smooth
metal
vessel (e.g., a S00 ml volume cylinder), scraping off the excess from the heap
above the
rim of the vessel, measuring the remaining mass of powder and dividing the
mass by the
volume of the vessel. As used herein, the term "substantially sticky
surfactants" refers to
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a surfactant or surfactant blend system consisting primarily of surfactants
which
substantially contribute lump-gel formation in cold temperature washing
solutions,
including the general classes of alkyl benzene sulfonates, alkyl ethoxy
sulfates, and
nonionic surfactants. As used herein, the phrase "substantially non-sticky
surfactant"
refers to a surfactant or surfactant blend system consisting primarily of
surfactants which
do not substantially contribute to lump-gel formation in cold temperature
washing
solutions, such as linear-chain alkyl sulfates with an average alkyl carbon
chain length of
at least 12. As used herein, all specifications of level of composition and
size distribution
are done on a mass basis unless otherwise specified. In cases where level is
specified on a
number basis, the calculations used to convert from a mass to number basis are
contained
in Example III set forth hereinafter.
It has been found that "lump-gel formation" can be avoided by minimizing the
"bridging" effect or contact points between particles which tend to be
"sticky" such as
particles containing surfactant systems consisting primarily of substantially
sticky
surfactants. This is achieved by the present invention by formulating the
detergent
composition with selectively decreased levels of surfactant-containing
particles, wherein
the "level" is based on the total "number fraction" of discrete particles in
the composition.
Also, the particle size and its distribution breadth (i.e. range of
distribution) of the
substantially sticky particles are optimally selected. Further elimination of
the "bridging"
effect which causes undesirable dissolution problems are achieved by
increasing the level
of other particulate components which typically are not "sticky", and
therefore, do not
lend themselves easily to "bridging" particles together into clumps or lump-
gel formation.
Again, the level of the non-sticky particles is based on the total number of
discrete
particles in the detergent composition. The physical properties, such as
particle size and
distribution and density, of the substantially non-sticky particles are also
optimally
selected. It should be understood that the "discrete particles" which contain
surfactants or
other ingredients such as inorganic builders can be in the form of admixed
particles,
spray-dried granules, and/or agglomerates, depending upon the desired overall
formulation and product density.
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6
While not intending to be bound by theory, it is believed that by selecting
relatively large and relatively high density substantially sticky particles
with moderate to
high levels of surfactant in each discrete particle in combination with
relatively small
substantially non-sticky particles, the "bridging" effect can be greatly
reduced in that
there are relatively few (or at least fewer) contact points between so-called
"sticky"
surfactant-containing particles. This, in turn, reduces lump-gel formation
resulting in
improved dispersion and dissolution of the detergent composition in aqueous
laundering
solutions, especially in solutions at low temperatures. It should be
understood, however,
that the physical properties of the detergent composition should be maintained
within
reasonable limits so as to assure that typical detergent composition product
attributes are
maintained. For example, although a larger size of a sticky particle may help
promote .
better dispersion, the particle size of the sticky particles should not be
extremely large
such that they require an inordinate amount of time before which they dissolve
in the
aqueous laundering solution. Similarly, the particle size of the substantially
non-sticky
particles should not be extremely small and have a very Iow density such that
the
detergent composition is extremely "dusty". Finally, the balance between the
larger
substantially sticky particles and the smaller substantially non-sticky
particles should be
selected so as to avoid significant product segregation in the detergent
product box prior
to use. As stated previously, the present invention provides an optimal
selection of the
various physical properties to provide the desired improved dissolution
performance
improvement.
To that end, the mass-based geometric mean particle size diameter of the
substantially sticky particles is preferably of from about 300 microns to
about 700
microns with a geometric standard deviation of less than about I .8, more
preferably of
from about 350 microns to about 650 microns with a geometric standard
deviation of less
than about 1.7, and most preferably about 400 microns to about 600 microns
with a
geometric standard deviation of less than about 1.6. Preferred compositions
include
substantially sticky particles having at least about I S%, more preferably
from about at
least about 35%, and most preferably at least about 45%, by weight of the
sticky particles,
of a substantially sticky surfactant. Although a wide variety of sticky
surfactants are
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7
suitable for use in the detergent compositions of the invention, an especially
preferred
substantially sticky surfactant is a potassium salt of a surfactant selected
from the group
consisting of linear alkyl benzenes, alkyl ethoxy sulfates, and mixtures
thereof. The
average bulk density of the substantially sticky particles is preferably at
least about 450
g/1, more preferably at Ieast about 550 g/1, and most preferably at least
about 650 g/l.
Preferably, the geometric mean particle size diameter of the substantially non-
sticky particles is preferably of from about 200 microns to about 500 microns
with a
geometric standard deviation of greater than about 1.2, more preferably of
from about 250
microns to about 450 microns with a geometric standard deviation of greater
than about
1.4, more preferably of from about 300 microns to about 400 microns with a
geometric
standard deviation of greater than about 1.6. Preferred compositions include
inorganic
builder-containing particles having less than about 10%, more preferably less
than about
5%, and most preferably less than about 1 %, by weight of the non-sticky
particles, of a
substantially sticky surfactant. The average bulk density of the non-sticky
particles is
preferably less than about 850 g/1, more preferably less than about 650 g/l,
and most
preferably less than about 500 g/1..
Although a wide variety of inorganic builders are suitable for use in the
substantially non-sticky particles of the invention, especially preferred non-
sticky
particles comprise sodium or potassium salts selected from the group
consisting of
sodium chloride, sodium carbonate, sodium sulfate, tetrasodium pyrophosphate,
trisodium
pyrophosphate, disodium pyrophosphate, monosodium pyrophosphate, potassium
chloride, potassium carbonate, potassium sulfate, tetrapotassium
pyrophosphate,
tripotassium pyrophosphate, dipotassium pyrophosphate, monopotassium
pyrophosphate
and mixtures thereof. Additional dissolution enhancements are achieved when
the
composition comprises from about 0.05% to about 50% by weight of potassium
preferably from about 0.5% to about 30%, more preferably from about 1 % to
about 20%,
by weight, of potassium ions, regardless of the source from which the
potassium ions
derive. Typically, however, potassium ions useful herein are derived from
potassium
salts. Some of non-limiting examples of the potassium salts useful herein are
potassium
CA 02318491 2003-O1-21
salts of alkali builders (e.g. potassium salt of carbonates, potassium salt of
silicates),
potassium salt of mid-chain branched surfactants, and mixtures thereof.
Of the potassium salts, inorganic potassium salts are preferred, and are more
preferably selected from the group consisting of potassium chloride (KCl),
potassium
carbonate (KZCO3), potassium sulfate (KZSO4), and mixtures thereof. These are
commercially available. Potassium carbonate is most preferred. Inorganic
potassium
salts may include dehydrated (preferably) or hydrated tetrapotassium
pyrophosphate
(K4P20~; preferred), tripotassium pyrophosphate (HK3PZ0~), dipotassium
pyrophosphate
(H~K~PzO~), and monopotassium pyrophosphate (H3KPz0~). Of the hydrates, those
which
are stable up to about 120°F (48.9°C) are preferred. Other
potassium salts for use herein
are dehydrated (preferably) or hydrated pentapotassium tripolyphosphate
(KSP30~°),
tetrapotassium tripolyphosphate (KSP30~°), tetrapotassium
tripolyphosphate (HK4P30~~,
tripotassium tripolyphosphate (HZK3P30~°), dipotassium tripolyphosphate
(H3KiP~01°),
and monopotassium tripolyphosphate (H4KP30~°); potassium hydroxide
(KOH);
potassium silicate; and potassium neutralized surfactant such as potassium
longer alkyl
chain, mid chain-branched surfactant compounds, liner potassium alkylbenzene
sulfonate,
potassium alkyl sulfate, and/or potassium alkylpolyethoxylate.
Also suitable for use herein are salts of film forming polymers as described
in U.S.
Fat. No. 4,379,080, Murphy, issued Apr. S, 1983, column 8, line 44 to column
10, line 37,
which are either partially or wholly neutralized with potassium.
Particularly preferred are the potassium salts of copolymers of acrylamide and
acrylate
having a molecular weight between about 4,000 and 20,000. In addition, the
combination
of both types of the aforementioned particles must net an overall particle
size distribution
that has less than about 5% fine and less than about 5% oversize particles,
where the fine
limit is defined at 150 microns and the oversize limit is defined at 1180
microns.
Sticky Detersive Surfactants
Nonlimiting examples of the preferred substantially sticky surfactants include
anionic surfactants which include the conventional C 11-C 1 g alkyl benzene
sulfonates,
branched-chain and random C 1 p-C2p alkyl sulfates, the C 10-C 1 g secondary
(2,3) alkyl
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9
sulfates of the formula CH3(CH2)x(CHOS03-M+) CH3 and CH3
(CH2)y(CHOS03-M+) CH2CH3 where x and (y + I) are integers of at least about 7,
preferably at least about 9, and M is a water-solubilizing cation, especially
sodium or
potassium, unsaturated sulfates such as oleyl sulfate, and the C 1 p-C 1 g
alkyl alkoxy
sulfates ("AExS"; especially EO 1-7 ethoxy sulfates).
Optionally, other exemplary surfactants useful include and C 1 p-C 1 g alkyl
alkoicy
carboxylates (especially the EO 1-5 ethoxycarboxylates), the C 1 Q-I g
glycerol ethers, the
C 1 ~-C 1 g alkyl polyglycosides and their corresponding sulfated
polyglycosides, and
C 12-C 1 g alpha-sulfonated fatty acid esters. If desired, the conventional
nonionic and
amphoteric surfactants such as the C 12-C I g alkyl ethoxylates including the
so-called
narrow peaked alkyl ethoxylates and C6-C12 alkyl phenol alkoxylates
(especially
ethoxylates and mixed ethoxyfpropoxy), C 12-C I g betaines and sulfobetaines
("sultaines"), C 1 p-C 1 g amine oxides, and the like, can also be included in
the overall
compositions. The C 1 p-C 1 g N-alkyl polyhydroxy fatty acid amides can also
be used.
Typical examples include the C12-C1 g N-methylglucamides. See WO 92106154.
Other
sugar-derived surfactants include the N-alkoxy polyhydroxy fatty acid amides,
such as
C 1 p-C I g N-(3-methoxypropyl) glucamide. 'The N-propyl through N-hexyl C 12-
C 18
glucamides can be used for low sudsing. C I p-C2p conventional soaps may also
be used.
If high sudsing is desired, the branched-chain C 1 p-C 16 soaps may be used.
Mixtures of
anionic and nonionic surfactants are especially useful. Other conventional
useful
surfactants are listed in standard texts.
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1
Inorgan[c Builders
. A variety inorganic builders are suitable for use herein and include
aIuminosilicates, crystalline layered silicates, MAP zeolites, citrates,
amorphous silicates,
sodium carbonates and mixtures thereof. The aluminosilicate ion exchange
materials
used herein as a detergent builder preferably have both a high calcium ion
exchange
capacity and a high exchange rate. Without intending to be limited by theory,
it is
believed that such high calcium ion exchange rate and capacity are a function
of several
interrelated factors which derive from the method by which the aluminosilicate
ion
exchange material is produced. In that regard, the aluminosilicate ion
exchange materials
used herein are preferably produced in accordance with Corkill et al, U.S.
Patent No.
4,605,509 (Procter & Gamble),
Preferably, the aluminosilicate ion exchange material is in "sodium" form
since the
potassium and hydrogen forms of the instant aluminosilicate do not exhibit the
as high of an
exchange rate and capacity as provided by the sodium form. Additionally, the
aluminosilicate ion exchange material preferably is in over dried form so as
to facilitate
production of crisp detergent agglomerates as described herein. The
aluminosilicate ion
exchange materials used herein preferably have particle size diameters which
optimize their
effectiveness as detergent builders. The term "particle size diameter" as used
herein
represents the average particle size diameter of a given aluminosilicate ion
exchange material
as determined by conventional analytical techniques, such as microscopic
determination and
scanning electron microscope (SEM). The preferred particle size diameter of
the
aluminosilicate is from about 0.1 micron to about 10 microns, more preferably
from about
0.5 microns to about 9 microns. Most preferably, the particle size diameter is
from about l
microns to about 8 microns.
Preferably, the aluminosilicate ion exchange material has the formula
Naz[(A102)z.(Si42)y]xH20
wherein z and y are integers of at least 6, the molar ratio of z to y is from
about 1 to about S
and x is from about 10 to about 264. More preferably, the aiuminosilicate has
the formula
Nal2[(A102)12~(Si02)12]~20
CA 02318491 2003-O1-21
wherein x is from about 20 to about 30, preferably about 27. These prefen:ed
aluminosilicates are available commercially, for example under designations
Zeolite A,
Zeolite B and Zeolite X. Alternatively, naturally-occurring or synthetically
derived
aluminosilicate ion exchange materials suitable for use herein can be made as
described in
Krummel et al, U.S. Patent No. 3,985,669.
The aluminosilicates used herein are further characterized by their ion
exchange
capacity which is at least about 200 mg equivalent of CaC03 hardness/gram,
calculated on
an anhydrous basis, and which is preferably in a range from about 300 to 352
mg equivalent
of CaC03 hardness/gram. Additionally, the instant aluminosilicate ion exchange
materials
are still further characterized by their calcium ion exchange rate which is at
least about 2
grains Ca'~/gallonJminute/-gram/gallon, and more preferably in a range from
about 2 grains
Ca'~/gallon/minute/-gram/gallon to about 6 grains Ca'~/gallon/minute/-
gram/gallon .
1n comparison with amorphous sodium silicates, crystalline layered sodium
silicates
exhibit a clearly increased calcium and magnesium ion exchange capacity. In
addition, the
layered sodium silicates prefer magnesium ions over calcium ions, a feature
necessary to
insure that substantially all of the "hardness" is removed from the wash
water. These
crystalline layered sodium silicates, however, are generally more expensive
than amorphous
silicates as well as other builders. Accordingly, in order to provide an
economically feasible
laundry detergent, the proportion of crystalline layered sodium silicates used
must be
determined judiciously.
The crystalline layered sodium silicates suitable for use herein preferably
have the
formula
NaMSix02x+1 ~YH20
wherein M is sodium or hydrogen, x is from about 1.9 to about 4 and y is from
about 0 to
about 20. More preferably, the crystalline layered sodium silicate has the
formula
NaMSi2O5.yH20
wherein M is sodium or hydrogen, and y is from about 0 to about 20. These and
other
crystalline layered sodium silicates are discussed in Corkill et al, U.S.
Patent No. 4,605,509 .
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12
Adjunct ingredients include other detergency builders, bleaches, bleach
activators,
suds boosters or suds suppressors, anti-tarnish and anticorrosion agents, soil
suspending
agents, soil release agents, germicides, pH adjusting agents, non-builder
alkalinity
sources, chelating agents, smectite clays, enzymes, enzyme-stabilizing agents
and
perfumes. See U.S. Patent 3,936,537, issued February 3, 1976 to Baskerville,
Jr. et al.
Water-soluble, nonphosphorus organic builders useful
herein include the various alkali metal, ammonium and substituted ammonium
polyacetates, carboxylates, polycarboxylates and polyhydroxy sulfonates.
Examples of
polyacetate and polycarboxylate builders are the sodium, potassium, lithium,
ammonium
and substituted ammonium salts of ethylene diamine tetraacetic acid,
nitrilotriacetic acid,
oxydisuccinic acid, mellitic acid, benzene polycarboxylic acids, and citric
acid.
Polymeric polycarboxylate builders are set forth in U.S. Patent 3,308,067,
Diehl,
issued March 7, 1967. Such materials include the water-
soluble salts of homo- and copolymers of aliphatic carboxylic
acids such as malefic acid, itaconic acid, mesaconic acid, fumaric acid,
aconitic-acid,
citraconic acid and methylene malonic acid. Some of these materials are useful
as the
water-soluble anionic polymer as hereinafter described, but only if in
intimate admixture
with the non-soap anionic surfactant.
Other suitable polycarboxylates for use herein are the polyacetal carboxylates
described in U.S. Patent 4,144,226, issued March 13, 1979 to Crutchfield et
al, and U.S.
Patent 4,246,495, issued March 27, 1979 to Crutchfield et al .
These polyacetal carboxylates can be prepared by
bringing together under polymerization conditions an ester of glyoxylic acid
and a
polymerization initiator. The resulting polyacetal carboxylate ester is then
attached to
chemically stable end groups to stabilize the polyacetal carboxylate against
rapid
depolymerization in alkaline solution, converted to the corresponding salt,
and added to a
detergent composition. Particularly preferred polycarboxylate builders are the
ether
carboxylate builder compositions comprising a combination of tartrate
monosuccinate and
tartrate disuccinate described in U.S. Patent 4,663,071, Bush et al., issued
May 5, 1987.
CA 02318491 2003-O1-21
13
Bleaching agents and activators are described in U.S. Patent 4,412,934, Chung
et al.,
issued November 1, 1983, and in U.S. Patent 4,483,781, Hartman, issued
November 20,
1984. Chelating agents are also described in U.S. Patent
No. 4,633,071, Bush et al., from Column 17, line 54 through
Column 18, line 68. Suds modifiers are also optional ingredients
and are described iri U.S. Patents 3,933,672, issued January 20, 1976 to
Bartoletta et al., and
4,136,045, issued January 23, 19?9 to Gault et al.
Suitable smectite clays far use herein are described in U.S. Patent 4,762,645,
Tucker
et al, issued August 9, 1988, Column 6, line 3 through Column 7, line 24.
Suitable
additional detergency builders for use herein are enumerated in
the Baskerville patent, Column 13, line 54 through Column 16, line 16, and in
U.S. Patent
4,663,071, Bush et al, issued May 5, 1987 .
In order to make the present invention more readily understood, reference is
made
to the following examples, which are intended to be illustrative only and not
intended to
be limiting in scope.
EXAMPLES I-II
The following Examples illustrate detergent compositions within the scope of
the
invention as well as a Control example to illustrate a composition outside the
scope of the
invention. The specific detergent ingredients and relative proportions are
shown below,
wherein "LAS" means C,~_" linear alkylbenzene sulfonate surfactant, "AS" means
C,4.,5
alkyl sulfate surfactant, "AES" means C".,s alkyl ethoxy (EO = 3) sulfate
surfactant, and
"65/25/10" is a percentage weight ratio:
Control I II
Weight Weight Weight
% %
Spray-dried granules TOTAL49.41 36.45 46.07
65125110 LAS:AS:AES 9.95 0.00 0.00
Aluminosilicate, Na 14.06 14.25 22.09
Sodium carbonate 11.86 13.81 14.27
Sodium silicate 0.58 0.58 0.58
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14
Polyacrylate 2.26 2.26 2.26
Polyethylene glycol MW 1.01 1.26 0.51
= 4000
Brightener 0.17 0.17 0.17
Sodium sulfate 5.46 0.00 0.00
Moisture 3.73 3.78 5.85
Agglomerates TOTAL 38.99 54.13 38.99
65/25/10 LAS:AS:AES 11.70 21.65 21.65
Aluminosilicate, Na 13.72 13.53 5.69
Sodium carbonate 8.11 13.53 5.69
Sodium sulfate O.UO 2.37 0.00
Polyethylene glycol MW 0.58 0.32 1.08
= 4000
Moisture 4.87 2.71 4.87
Admixed components
Sodium carbonate 7.37 0.00 7.37
Sodium perborate 1.03 1.03 1.03
Cellulase enzyme 0.33 0.33 - 0.33
Protease enzyme 0:13 0.13 0.13
Perfume 0.42 0.42 0.42
Misc and moisture --balance----balance----balance--
The spray-dried granules are prepared using a standard spray drying process in
which the
ingredients are mixed together to form a slurry which is then sprayed into a
spray drying
tower to form spray dried granules. The detergent agglomerates are prepared by
combining the surfactant paste and other ingredients together in one or more
mixers until
detergent agglomerates are formed. The admixed components are simply added to
the
granules and agglomerates if it a dry ingredient and sprayed on if in liquid
form. The
various physical properties of the compositions are shown below:
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Physical Properties
Control I II
Spray dried granules
Total sticky surfactant 19.9 0 0
level (wt. %)
Mean particle diameter 250 350 350
(microns)
Particle size standard 1.5 1.5 1.5
deviation
Bulk density (g/I) 400 450 450
Agglomerates/Admixes
Mean particle diameter 400 400 400
(microns)
Particle size standard 1.7 1.7 1.7
deviation
Bulk density (g/1) 850 700 670
The Control composition is a typical detergent composition having about 90% of
substantially sticky particles (spray dried granules plus agglomerates) based
on the total
number of particles in the composition. As a result, the Control composition
has a high
number of sticky particle contact points which renders it susceptible to
"bridging" effects
ultimately causing lump-gel formation. By contrast, the Example I and II
compositions
only contain sticky surfactants in the higher-density agglomerates, and
therefore, have
about 30% or fewer sticky particles, based on the total number of particles in
the
composition. Unexpectedly, Examples I and II have a much better ROOA ("Reverse
Order Of Addition") grade and experience less residual mass in the washing
machine and
on the clothes subsequent to standard laundering operations.
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16
EXAMPLE III
Calculation of Darticle number percentages based on the total number of
discrete particles
in a detergent composition
This Example illustrates one of the many means by which the particle number
percentage of sticky particles and/or non-sticky particles can be determined
relative to the
total number of discrete particles in the composition. The input variables
describe the
physical characteristics of each admixture component within the mixture:
w; weight of component i in the composition;
d; geometric mean particle size on a mass basis; ~
a; geometric standard deviation of the particle size distribution on a mass
basis;
p; bulk density.
In order to quantify the potential for bridging between particles, we want to
consider the number distribution of particles in the admixture. On the other
hand, it is
recognized that virtually all bulk powder manufacturing operations operate on
the basis of
mass. Therefore, it is desired to use the mass fractions of particulate
components as the
basis for defining the admixture, and convert from mass to number basis.
First, the weight fraction of each mixture component, w;, is converted to the
total
mixture volume fraction, V;. This is done using an intermediate volume, v;,
and the
component bulk density, p; (eq. Al). The component volumes are normalized to
total
mixture volume fractions (eq. A2).
w
conversion of weight to volume (A1)
v; _ ''t y~ ; volume fraction of component i in mixture (A2)
k
A numerical method is used to convert the massed-based distribution to a
number
basis. For each component (i), consider a range of n size class values (j),
x;~, where:
log(xj~~=log(d;~-3xlog(cr} ; fines limit (A3)
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I7
log(x;" ) = log(d; ) + 3 x log(a; ) ; coarse limit (A4)
and the intermediate values (j = 2 to n-1) are distributed at equal intervals
of ~log(x),
where Olog(x) _ [log(x;~)-log(x;,)]/30. The log-normal distribution describes
a differential
mass fraction per log(size), y;~, as follows (eq. AS).
2
y;; = 1 x ex (log(x,, ) log(d, )) ; log normal distribution function (AS)
2n log(a; ~ 2 x (log(a; )~
Converting from mass to number population, we calculate a population, z;~, of
particles (i)
associated with each discrete mass fraction (eq. A6), and a normalized
population, Z;~, (eq.
A7).
z~ =C~)y j ~(x,~) 3 ; population of particle i in size class j (A6)
The number density, n;, of component i particles is defined as the population
of
component (i) particles per unit volume of mixture; this is the product of the
volume
fraction and the sum of the (i) populations over all size classes, j (eq. A7).
The number
fraction, N;, of each component is calculated by normalizing the number
population over
all components in the mixture (eq. A8). The number percent is simply the
number
fraction times 100.
n, = v, . ~ z f ; number density, or population of particle i per unit (A7)
volume of mixture, summed over all size classes, j
Nl = nr f ; number fraction of component i particles in the full (A8)
ng
admixture
Having thus described the invention in detail, it will be obvious to those
skilled in
the art that various changes may be made without departing from the scope of
the
invention and the invention is not to be considered limited to what is
described in the
specification.
