Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROCESS FOR MAKING A LOW DENSITY DETERGENT COMPOSITIOV BY
CONTROLLING NOZZLE HEIGHT IN A FLUID BED DRYER
FIELD OF THE INVENTION
The present invention generally relates to a process for producing a low
density
detergent composition. More particularly, the invention is directed to a
process during
which low density detergent agglomerates are produced by feeding a surfactant
paste or
liquid acid precursor of anionic surfactant and dry starting detergent
material sequentially
into two high speed mixers followed by a fluid bed dryer which has an
optimally selected
nozzle height for spraying on a binder. The process produces a free flowing,
low density
detergent composition which can be commercially sold as a conventional non-
compact
detergent composition or used as an admix in a low dosage, "compact" detergent
product.
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 bulk density detergents, for example with a density of
600 g/1 or
higher. The 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.
However, the
extent to which modern detergent products need to be "compact" in nature
remains
unsettled. In fact, many consumers, especially in developing countries,
continue to prefer a
higher dosage levels in their respective laundering operations. Consequently,
there is a
need in the art of producing modern detergent compositions for flexibility in
the ultimate
density of the final composition.
Generally, there are two primary types of processes by which detergent
granules or
powders can be prepared. The first type of process involves spray-drying an
aqueous
detergent slurry in a spray-drying tower to produce highly porous detergent
granules. In
the second type of process, the various detergent components are dry mixed
after which
they are agglomerated with a binder such as a nonionic or anionic surfactant.
In both
processes, the most important factors which govern the density of the
resulting detergent
granules are the density, porosity and surface area, shape of the various
starting materials
and their respective chemical composition. These parameters, however, can only
be varied
within a limited range. Thus, flexibility in the substantial bulk density can
only be
achieved by additional processing steps which lead to lower density of the
detergent
granules.
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There have been many attempts in the art for providing processes which
increase
the density of detergent granules or powders. Particular attention has been
eiven to
densification of spray-dried granules by post tower treatment. For example,
one attempt
involves a batch process in which spray-dried or granulated detergent powders
containing
sodium tripolyphosphate and sodium sulfate are densified and spheronized in a
Marumerizer~. This apparatus comprises a substantially horizontal, roughened,
rotatable
table positioned within and at the base of a substantially vertical, smooth
walled cylinder.
This process, however, is essentially a batch process and is therefore less
suitable for the
large scale production of detergent powders. More recently, other attempts
have been made
to provide continuous processes for increasing the density of "post-tower" or
spray dried
detergent granules. Typically, such processes require a first apparatus which
pulverizes or
grinds the granules and a second apparatus which increases the density of the
pulverized
granules by agglomeration. While these processes achieve the desired increase
in density
by treating or densifying "post tower" or spray dried granules, they do not
provide a process
which has the flexibility of providing lower density granules.
Moreover, all of the aforementioned processes are directed primarily for
densifying
or otherwise processing spray dried granules. Currently, the relative amounts
and types of
materials subjected to spray drying processes in the production of detergent
granules has
been limited. For example, it has been difficult to attain high levels of
surfactant in the
resulting detergent composition, a feature which facilitates production of
detergents in a
more efficient manner. Thus, it would be desirable to have a process by which
detergent
compositions can be produced without having the limitations imposed by
conventional
spray drying techniques.
To that end, the art is also replete with disclosures of processes which
entail
agglomerating detergent compositions. For example, attempts have been made to
agglomerate detergent builders by mixing zeolite and/or layered silicates in a
mixer to form
free flowing agglomerates. While such attempts suggest that their process can
be used to
produce detergent agglomerates, they do not provide a mechanism by which
conventional
starting detergent materials in the form of surfactant pastes or precursors
thereof, liquids
and dry materials can be effectively agglomerated into crisp, free flowing
detergent
agglomerates having low densities rather than high densities. In the past,
attempts at
producing such low density agglomerates involves a nonconventional detergent
ingredient
which is typically expensive, thereby adding to the cost of the detergent
product. One such
example of this involves a process of agglomerating with inorganic double
salts such as
Burkeite to produce the desired low density agglomerates.
Accordingly, there remains a need in the art to have a process for producing a
low
density detergent composition directly from starting detergent ingredients
without the need
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for relatively expensive specialty ingredients. Also, there remains a need for
such a process
which is more efficient, flexible and economical to faciiitate large-scaie
production of
detergents of low as well as high dosage levels.
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4
BACKGROUND ART
The following references are directed to densifying spray-dried granules:
Appel et
al. U.S. Patent No. 5,133,924 (Lever); Bortolotti et al, U.S. Patent No.
5,160,657 (Lever);
Johnson et al, British patent No. 1,517,713 (Unilever); and Curtis, European
Patent
Application 451,894. The following references are directed to producing
detergents by
agglomeration: Beerse et at, U.S. Patent No. 5,108,646 (Procter & Gamble);
Capeci et al,
U.S. Patent No. 5.366,652 (Procter & Gamble); Hollingsworth et al, European
Patent
Application 351,937 (Unilever); and Swatting et al, U.S. Patent No. 5,205,958.
The
following references are directed to inorganic double salts: Evans et al, U.S.
Patent No.
I O 4,820,441 (Lever); Evans et al, U.S. Patent No. 4,818,424 (Lever);
Atkirison et al, U.S.
Patent No. 4,900,466 (Lever); France et al, U.S. Patent No. 5,576,285 (Procter
& Gamble);
and Dhalewadika et al, PCT WO 96/04359 (Unilever).
SUMMARY OF THE INVENTION
The present invention meets the aforementioned needs in the art by providing a
15 process which produces a low density (below about 600 g/1) detergent
composition directly
from a surfactant paste and dry starting detergent ingredients. In essence,
the process
involves agglomerating the starting detergent ingredients in a high speed
mixer followed by
a second high speed mixer. Thereafter, the agglomerates formed in the high
speed mixers
are agglomerated and dried in a fluid bed dryer in which a liquid binder is
sprayed onto the
20 agglomerates from one or more nozzles at a selected height from the
distribution plate of
the fluid bed dryer. The process does not use the conventional spray drying
towers
currently used and is therefore more efficient, economical and flexible with
regard to the
variety of detergent compositions which can be produced in the process.
Moreover, the
process is more amenable to environmental concerns in that it does not use
spray drying
25 towers which typically emit particulates and volatile organic compounds
into the
atmosphere.
As used herein, the term "agglomerates" refers to particles formed by
agglomerating detergent granules or particles which typically have a smaller
median
particle size than the formed agglomerates. By "median particle size", it is
meant the
30 particle size diameter value above which SO% of the particles have a larger
particle size and
below which 50% of particles have a smaller particle size. All percentages
used herein are
expressed as "percent-by-weight" on an anhydrous basis unless indicated
otherwise.
In accordance with one aspect of the invention, a process for preparing low
density
detergent agglomerates is provided. The process comprises the steps of: (a)
agglomerating
35 a detergent surfactant paste or precursor thereof and dry starting
detergent material in a first
high speed mixer to obtain agglomerates; (b) mixing the agglomerates in a
second high
speed mixer to obtain built-up agglomerates; and (c) feeding the built-up
agglomerates into
CA 02295941 2002-06-12
a fluid bed dryer in which a binder is sprayed via a nozzle having a height of
from about 2~
cm to about 60 cm from the distributor plate of the fluid bed dryer such that
the built-up
agglomerates are dried and agglomerated to form the low density detergent
agglomerates
having a density in a range from about 300 g/1 to about 550 g/1.
In accordance with another aspect of the invention, another process for
preparing
low density detergent agglomerates is provided. The process comprises the
steps of: (a)
agglomerating a detergent surfactant paste or precursor thereof and dry
starting detergent
material in a first high speed mixer to obtain agglomerates; (b) mixing the
agglomerates in
a second high speed mixer to obtain built-up agglomerates; and (c) feeding the
built-up
agglomerates into a fluid bed dryer in which sodium silicate is sprayed via a
nozzle having
a height of from about 40 cm to about GO cm from the distributor plate of the
fluid bed
dryer such that the built-up agglomerates are dried and agglomerated to form
the low density
detergent agglomerates having a density in a range from about 300 g/1 to about
550 g,~l.
The detergent products made in accordance with any of the process embodiments
described
herein are also provided.
Accordingly, it is an object of the invention to provide a process for
producing a
low density detergent composition directly from starting detergent ingredients
which does
not include relatively expensive specialty ingredients. It is also an object
of the invention
to provide such a process which is more efficient, flexible and economical so
as to facilitate
large-scale production of detergents of low as well as high dosage levels.
These and other
objects, features and attendant advantages of the present invention will
become apparent to
those skilled in the art from a reading of the following detailed description
of the preferred
embodiment and the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention is directed to a process in which low density
agglomerates
are produced by a three step process, the last of which involves a fluid bed
dryer containing
one or more nozzles positioned at a selected height from the distribution
plate of the dryer.
In this way, the process forms free flowing, low density detergent
agglomerates which can
be used alone as the detergent product or as an admixture with conventional
spray-dried
detergent granules and/or high density detergent agglomerates in a final
commercial
detergent product. It should be understood that the process described herein
can be
operated cpntinuously or in a batch mode depending upon the particularly
desired
application. One major advantage of the present process is that it utilizes
equipment which
can be operated differently from the present process parameters to obtain high
density
detergent compositions. Thus, a single large-scale commercial detergent
manufacturing
facility can be built to produce high or low density detergent compositions
depending upon
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the local consumer demand and its inevitable fluctuations between compact and
non-
compact detergent products.
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Process
In the first step of the process. a detergent surfactant paste or precursor
thereof as
set forth in more detail hereinafter and dry starting detergent material is
inputted and
agglomerated in a high speed mixer. Unlike previous processes in this area,
the dry starting
material can include only those relatively inexpensive detergent materials
typically used in
modern granular detergent products. Such ingredients, include but are not
limited to,
builders, fillers, dry surfactants, and flow aides. Preferably, the builder
includes
aluminosilicates, crystalline layered silicates, phosphates, carbonates and
mixtures thereof
which is the essential dry starting detergent ingredient within the scope of
the current
process. Relatively expensive materials such as Burkeite (Na2S04~Na2C03) and
the
various silicas are not necessary to achieve the desired low density
agglomerates produced
by the process. Rather, by selecting the binder and nozzle height through
which the binder
is sprayed onto the agglomerates in the fluid bed dryer as described in more
detail
hereinafter, the present process achieves the desired low density. Further, it
is preferable to
include from 1 % to about 40% by weight of undersized detergent particles or
"fines" in the
first step of the process. This can be conveniently accomplished by screening
the detergent
particles formed subsequent to the fluid bed dryer to a median particle size
range of from
about 10 microns to about 150 microns and feeding these "fines" back into the
first high
speed mixer.
The high speed mixer can be any one of a variety of commercially available
mixers
TM
such as a Lodige CB 30 mixer or similar brand mixer. These types of mixers
essentially
consist of a horizontal, hollow static cylinder having a centrally mounted
rotating shaft
around which several shovel and rod-shaped blades are attached which have a
tip speed of
from about 5 m/s to about 30 m/s, more preferably from about 6 m/s to about 26
mls.
Preferably, the shaft rotates at a speed of from about 100 rpm to about 2500
rpm, more
preferably from about 300 rpm to about 1600 rpm. Preferably, the mean
residence time of
the detergent ingredients in the high speed mixer is preferably in range from
about 2
seconds to about 45 seconds, and most preferably from about 5 seconds to about
15
seconds. This mean residence time is conveniently measured by dividing the
weight of the
mixer at steady state by throughput (kg/hr) flow. Another suitable mixer is
any one of the
TM TM
various Flexomix models available from Schugi (Netherlands) which are
vertically
positioned high speed mixers. This type of mixer is preferably operated at a
Froude Index
of from about 13 to about 32. See U.S. Patent 5,149,455 to Jacobs et al
(issued September
22, 1992) for a detailed discussion of this well-known Froude Index which is a
dimensionless number that can be optimally selected by those skilled in the
art.
In a prefen;ed embodiment of the process invention, a liquid acid precursor of
an
anionic surfactant is inputted with the dry starting detergent material which
at least includes
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a neutralizing agent such as sodium carbonate. The preferred liquid acid
surfactant
precursor is Cl 1-18 linear alkylbenzene sulfonate surfactant ("HLAS"),
although any acid
precursor of an anionic surfactant may be used in the process. A more
preferred
embodiment involves feeding a liquid acid precursor of C 12_ 14 linear
alkylbenzene
sulfonate surfactant with a C10-18 alkyl ethoxylated sulfate ("AS") surfactant
into the first
high speed mixer, preferably in a weight ratio of from about 5:1 to about 1:~,
and most
preferably, in a range of from about 1:1 to about 3:1 (HLAS:AS). The result of
such
mixing is a "dry neutralization" reaction between the HLAS and the sodium
carbonate
embodied in the dry starting detergent material, all of which forms
agglomerates. It is
preferable to add the HLAS before the addition of other surfactants such as AS
or alkyl
ethoxylate sulfate ("AES") surfactants so as to insure optimal mixing and
neutralization of
the HLAS in the first high speed mixer. In the second step of the process,
the detergent agglomerates formed in the first step are inputted into a second
high speed
mixer which can be the same piece of equipment as used in the first step or a
differern type
1 S of high speed mixer. For example, a Lodige CB mixer can be used in the
first step while a
Schugi mixer is used in the second step. in this second process step, the
agglomerates are
mixed and built-up further in a controlled fashion. In this step, a sufficient
amount of
binder can be inputted to facilitate agglomeration build-up in the mixer.
Typical binders
include liquid sodium silicate, a liquid acid precursor of an anionic
surfactant such as
HLAS, nonionic surfactant, polyethylene glycol or mixtures thereof.
In the next step of the process, the built-up agglomerates are inputted into a
fluid
bed dryer in which the agglomerates are dried and agglomerated to a median
particle size of
from about 300 microns to about 700 microns, more preferably from about 325
microns to
about 450 microns. The density of the agglomerates formed is from about 300
g/1 to about
550 g/1, more preferably from about 350 g/1 to about 500 gll, and even more
preferably
from about 400 g/1 to about 480 g/1. All of these densities are generally
below that of
typical detergent compositions formed of dense agglomerates or most typical
spray-dried
granules.
A binder as described previously is preferably added during this step to
enhance
formation of the desired agglomerates. In this regard, a particularly
preferred binder is
liquid sodium silicate in an amount of from about 0.1% to about 20% by weight
of the final
low density composition. The nozzle height through which the binder is added
is
preferably from about 25 cm to about 60 cm, more preferably from about 30 cm
to about b0
cm, most preferably from about 40 cm to about 60 cm, and even more preferably
at 40 cm,
from the distribution plate of the fluid bed dryer. Preferably all of the
nozzles used in the
fluid bed drying apparatus have such a height arrangement. Unexpectedly, it
has been
found that by selecting the nozzle height to be within the aforementioned
ranges, superior
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low density agglomerates are produced in the process from both a low density
and free
flowability standpoint.
Additionally. the benefits of the process in this regard can be enhanced by
maintaining the spray-on flux of the binder in the fluid bed to be from about
0.02 kQ. cm2/hr
to about 0.06 kg/cm2/hr, more preferably from about 0.04 kg/cm2/hr to about
0.05 '
kg/cm2/hr. Preferably, the air inlet temperature in the fluid bed dryer is
from about 100°C
to about 200°C, more preferably from about 110°C to about
130°C. Also, the unfluidized
bed height in fluid bed dryer is preferably from about 5 cm to about 20 cm. It
has also been
found that the process benefits can be enhanced by maintaining the fluidized
air flux in the
fluid bed dryer is from about 0.6 kg/m2/s to about 0.8 kg/m2/s. It has also
been found
beneficial to add the binder simultaneously at more than one location in one
or more of the
steps of the process. For example, the liquid silicate can be added at two
locations in the
fluid bed dryer, e.g., at or near the inlet port and at or near the exit port.
Also, the median
binder droplet diameter is from about 20 microns to about 150 microns, a
parameter which
enhances formation of the desired built-up agglomerates. Further in this
regard, the ratio of
the median binder droplet diameter to built-up agglomerate (exiting the second
high speed
mixer) particle diameter is preferably from about 0.1 to about 0.6.
Optionally, the process may involve adding the binder to both the second high
speed mixer as well as the fluid bed dryer. It has also been found beneficial
to add the
binder simultaneously at more than one location in one or more of the steps of
the process.
For example, the liquid silicate can be added at two locations in the fluid
bed dryer, e.g., at
or near the inlet port and at or near the exit port. As with the first and
second steps of the
process, the agglomerates are built-up from smaller sizes to large sized
particles having a
high degree of intraparticie porosity. The degree of intraparticle porosity is
preferably from
about 20% to about 40%, and most preferably from about 25% to about 35%. The
intraparticle porosity can be conveniently measured by standard mercury
porosimetry
testing.
Other optional steps contemplated by the present process include screening the
oversized detergent agglomerates in a screening apparatus which can take a
variety of
forms including but not limited to conventional screens chosen for the desired
particle size
of the finished detergent product. Other optional steps inciude conditioning
of the
detergent agglomerates by subjecting the agglomerates to additional drying
and/or cooling
by way of apparatus discussed previously.
Another optional step of the instant process entails finishing the resulting
detergent
agglomerates by a variety of processes including spraying and/or admixing
other
conventional detergent ingredients. For example, the finishing step
encompasses spraying
perfumes, brighteners and enzymes onto the finished agglomerates to provide a
more
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complete detergent composition. Such techniques and ingredients are well known
in the
art.
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Detergent Surfactant Paste or Precursor
The liquid acid precursor of anionic surfactant is used in the first step of
the
process, and in optional embodiments, as a liquid binder in the second and,~or
third essential
steps of the process. This liquid acid precursor will typically have a
viscosity measured at
30°C of from about 500 cps to about 5.000 cps. The liquid acid is a
precursor for the
anionic surfactants described in more detail hereinafter. A detergent
surfactant paste can
also be used in the process and is preferably in the form of an aqueous
viscous paste,
although other forms are also contemplated by the invention. This so-called
viscous
surfactant paste has a viscosity of from about 5.000 cps to about 100,000 cps,
more
preferably from about 10,000 cps to about 80,000 cps, and contains at least
about 10%
water, more preferably at least about 20% water. The viscosity is measured at
70°C and at
shear rates of about 10 to 100 sec.' 1. Furthermore, the surfactant paste, if
used, preferably
comprises a detersive surfactant in the amounts specified previously and the
balance water
and other conventional detergent ingredients.
The surfactant itself, in the viscous surfactant paste, is preferably selected
from
anionic, nonionic, zwitterionic, ampholytic and cationic classes and
compatible mixtures
thereof. Detergent surfactants useful herein are described in U.S. Patent
3,664,961, Norris,
issued May 23, 1972, and in U.S. Patent 3,919,678, Laughlin et al., issued
December 30,
1975. Useful cationic surfactants also include those described in U.S. Patent
4,222,905,
Cockrell, issued September 16, 1980, and in U.S. Patent 4,239,659, Murphy,
issued
December 16, 1980. Of the surfactants, anionics and nonionics are preferred
and anionics are
most preferred.
Nonlimiting examples of the preferred anionic surfactants useful in the
surfactant
paste, or from which the liquid acid precursor described herein derives,
include the
conventional C11-Clg alkyl benzene sulfonates ("LAS"), primary, branched-chain
and
random C10-C20 alkyl sulfates ("AS"), the C10-Clg secondary (2,3) alkyl
sulfates of the
formula CH3(CH2)x(CHOS03 M+) CH3 and CH3 (CH2)y(CHOS03 M+) CH2CH3
where x and (y + 1 ) are integers of at least about 7, preferably at least
about 9, and M is a
510 water-solubilizing cation, especially sodium, unsaturated sulfates such as
oleyl sulfate,
and the C10-Clg alkyl alkoxy sulfates ("AEXS"; especially EO 1-7 ethoxy
sulfates).
Optionally, other exemplary surfactants useful in the paste of the invention
include
and C 10-C 1 g alkyl alkoxy carboxylates (especially the EO 1-S
ethoxycarboxylates), the
C10-18 glycerol ethers, the C10-C1 g alkyl polyglycosides and their
corresponding sulfated
polyglycosides, and C12-Clg alpha-sulfonated fatty acid esters. If desired,
the
conventional nonionic and amphoteric surfactants such as the C 12-C 1 g alkyl
ethoxylates
("AE") including the so-called narrow peaked alkyl ethoxylates and C6-C12
alkyl phenol
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12
alkoxylates (especially ethoxylates and mixed ethoxyipropoxy), C 1 ~-C I g
betaines and
sulfobetaines ("sultaines"), CIO-Clg amine oxides, and the like, can also be
included in the
overall compositions. The C l p-C 1 g N-alkyl polyhydroxy fatty acid amides
can also be
used. Typical examples include the C12-C1g N-methylglucamides. See WO
9,206,154.
Other sugar-derived surfactants include the N-alkoxy polyhydroxy fatty acid
amides, such
as C 10-C 1 g N-(3-methoxypropyl) glucamide. The N-propyl through N-hexyl C 12-
C 1 g
glucamides can be used for low sudsing. C10-C20 conventional soaps may also be
used. If
high sudsing is desired, the branched-chain C l0-C 16 soaps may be used.
Mixtures of
anionic and nonionic surfactants are especially useful. Other conventional
useful
surfactants are listed in standard texts.
Dry Detergent Material
The starting dry detergent material of the present process preferably
comprises a
builder and other standard detergent ingredients such as sodium carbonate,
especially when
a liquid acid precursor of a surfactant is used as it is needed as a
neutralizing agent in the
I S first step of the process. Thus, preferable starting dry detergent
material includes sodium
carbonate and a phosphate or an aluminosilicate builder which is referenced as
an
aluminosilicate ion exchange material. A preferred builder is selected from
the group
consisting of aluminosilicates, crystalline layered silicates, phosphates,
carbonates and
mixtures thereof. Preferred phosphate builders include sodium
tripolyphosphate,
tetrasodium pyrophosphate and mixtwes thereof. Additional specific examples of
inorganic phosphate builders are sodium and potassium tripolyphosphate,
pyrophosphate,
polymeric metaphosphate having a degree of polymerization of from about 6 to
21, and
orthophosphates. Examples of polyphosphonate builders are the sodium and
potassium
salts of ethylene diphosphonic acid, the sodium and potassium salts of ethane
1-hydroxy-1,
1-diphosphonic acid and the sodium and potassium salts of ethane, 1,1,2-
triphosphonic
acid. Other phosphorus builder compounds are disclosed in U.S. Patents
3,159,581;
3,213,030; 3,422,021; 3,422,137; 3,400,176 and 3,400,148.
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) .
CA 02295941 2002-06-12
1~
Preferably, the aiuminosilicate 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 panicle 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
l0 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 1 microns to about 8 microns.
Preferably, the aluminosilicate ion exchange material has the formula
Naz[(A102)z.( Si02)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
5 and x is from about 10 to about 264. More preferably, the aluminosilicate
has the
formula
Na 12~~A102) 12~(Si02) 12]~20
wherein x is from about 20 to about 30, preferably about 27. These preferred
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 character7zed by their calcium ion
exchange rate which
is at least about 2 grains Ca'+'r/gallon/minute/-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 .
Adiunct Detereent Intredients
The starting dry detergent material in the present process can include
additional
detergent ingredients andlor, any number of additional ingredients can be
incorporated in
the detergent composition during subsequent steps of the present process.
These adjunct
CA 02295941 2002-06-12
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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
_ 3,936.37, issued February 3, 1976 to Baskerville, Jr. et ai .
Other builders can be generally selected from the various borates, polyhydroxy
sulfonates, polyacetates, carboxylates, citrates, tarnate mono- and di-
succinates, and
mixtures thereof. Preferred are the alkali metal, especially sodium, salts of
the above. In
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
1 S 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+l.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
NaMSi205.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.
Examples of nonphosphorus, inorganic builders are tetraborate decahydrate and
silicates having a weight ratio of Si02 to alkali metal oxide of from about
0.5 to about 4.0,
preferably from about 1.0 to about 2.4. 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
CA 02295941 2002-06-12
l~
acids such as malefic acid, itacontc 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, convened to the corresponding salt, and
added to a
detergent composition. Particularly prefer ed polycarboxylate builders are the
ether
carboxylate builder compositions comprising a combination of tarnate
monosuccinate and
tarnate disuccinate described in U.S. Patent 4,663,071, Bush et al., issued
May 5, 1987.
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 4,663,071, Bush et
al., from
Column 17, line 54 through Column 18, line 68. Suds modifiers are also
optional
ingredients and are described in U.S. Patents 3,933,672, issued January 20,
1976 to
Bartoletta et al., and 4,136,045, issued January 23, 1979 to Gault et al.
Suitable smectite clays for 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 example, which is intended to be illustrative only and not
intended to be
limiting in scope.
EXAMPLE
This Example illustrates the process invention in which a low density
agglomerated detergent composition is prepared. A Lodige CB 30 high speed
mixer is
charged with a mixture of powders, namely sodium carbonate (median particle
size 15
CA 02295941 1999-12-31
WO 99103966 PCT/US98/14100
16
microns) and sodium tripolyphosphate ("STPP") with a median particle size of
25 microns.
A liquid acid precursor of sodium alkylbenzene sulfonate surfactant (C 12H25-
C6H4-S03-
H or "HLAS" as noted below) and a 70% active aqueous C 10_I g alkyl
ethoxylated sulfate
surfactant (E0 = 3, "AES") paste are also inputted into the Lodige CB 30
mixer, wherein
the HLAS is added first. The mixer is operated at 1600 rpm and the sodium
carbonate,
STPP, HLAS and AES are formed into agglomerates having a median particle size
of
about 110 microns after a mean residence time in the Lodige CB 30 mixer of
about 5
seconds. The agglomerates are then fed to a Schugi (Model # FX160) high speed
mixer
which is operated at 2800 rpms with a mean residence time of about 2 seconds.
A HLAS
binder is inputted into the Schugi (Model # FX160) mixer during this step
which results in
built-up agglomerates having a median particle size of about 180 microns being
formed.
Thereafter, the built-up agglomerates are passed through a four-zone fluid bed
dryer which
is operated at an air inlet temperature of about 125°C and a nozzle
height of 40 cm from
the distribution plate in the first and fourth zones of the fluid bed. The
spray-on flux of the
sodium silicate in 0.04 kg/cm2/hr, the unfluidized bed height is 10 cm, and
the fluidized air
flux is 0.6 kg/m2/s. In the amounts and particle size specified below, fines
are also added
to the Lodige CB 30 mixer. In the first and fourth zones of the fluid bed
dryer, liquid
sodium silicate is fed into the fluid bed dryer resulting in the finished
detergent
agglomerates having a density of about 485 g/1 and a median particle size of
about 360
microns. Unexpectedly, the finished agglomerates have excellent physical
properties in
that they are free flowing as exhibited by their superior cake strength
grades.
The composition of the agglomerates are given below in Table I.
TABLEI
(% weight)
Component I
LAS (Na) 15.8
AES (E0 = 3) 4.7
Sodium carbonate 48.0
STPP 22.7
Sodium Silicate 5.5
Water 3.3
100.0
The agglomerates embody about 14% of fines (less than 150 microns) which are
recycled
from the fluid bed back into the Lodige CB 30 which enhances production of the
agglomerates produced by the process.
CA 02295941 1999-12-31
WO 99/03966 PCTNS98/14100
17
~/ J
Having thus described the invention in detail, it will be clear 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.
