Note: Descriptions are shown in the official language in which they were submitted.
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HIGH DENSITY DETERGENT-MAKING PROCESS USING A HIGH ACTIVE
SURFACTANT PASTE HAVING IMPROVED STABILITY
FIELD OF THE INVENTION
The present invention is generally directed to a process for making high
density
detergent compositions from a high active surfactant paste and other detergent
ingredients.
More particularly, the invention is directed to a process for producing a high
density
detergent composition in the form of agglomerates in which the stability and
shelf life of a
high active surfactant paste is unexpectedly improved and maintained. This
process is
especially useful in the production of modern compact granular detergent
compositions
I 5 which typically require higher levels of active detersive surfactants.
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
650 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.
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, various detergent components are mixed after which
they are
agglomerated with a nonionic or anionic detergent paste that also serves as
the binder for
the agglomerated particle itself. In both processes, the most important
factors which
govern the density of the resulting detergent granules are the density,
porosity and surface
area of the various starting materials and their respective chemical
composition. These
parameters, however, can only be varied within a limited range. Thus, a
substantial bulk
density increase can only be achieved by additional processing steps which
lead to
densification of the detergent granules or via build-up agglomeration
processes.
The art is replete with processes directed to agglomeration for producing
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. Yet
another example involves a starting detergent material in the form of highly
active,
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viscoelastic surfactant paste which is agglomerated with dry powders such as
aluminosilicates and carbonates into crisp, free flowing, highly dense
detergent
agglomerates. However, a wide variety of problems have been encountered with
handling
high active, highly viscoelastic surfactant pastes which are used to produce
high density,
high active detergent agglomerates suitable for modem low dosage detergent
products.
Specifically, such high active surfactant pastes are extremely sensitive to
environmental
and operating equipment parameters, all of which make the pastes difficult to
transport,
store and process when producing detergent agglomerates.
Typically, surfactant pastes are manufactured by a process in which fatty
alcohol is
sulfated, and thereafter, neutralized with an alkaline material (e.g. sodium
hydroxide). This
is an extremely delicate process, especially when used to produce high active
surfactant
pastes predominantly (greater than 60% by weight) containing the active
surfactant and
only a relatively minor amount of water and adjuncts. The resulting high
active surfactant
pastes are extremely sensitive to their environment, for example., high
temperature zones
1 S or "hot spots" in the equipment (pipes, valves, storage tanks and the
like) to which it is
exposed as well as any contaminants having a pH of less than 7 which make
their way into
the paste. In the event that the high active surfactant paste is exposed to
one or more of
these environmental factors, such high active pastes have a tendency to
undergo a
hydrolysis reaction, wherein the surfactant reverts back to its alcohol form.
This hydrolysis
reaction is an autocatalytic reaction in that a by-product is an acid which
continues to react
with any remaining surfactant. This threat of hydrolysis particularly
exacerbates the
environmental sensitivity of high surfactant pastes and renders them difficult
to keep stable
over periods of time (e.g. 2-7 days) necessary for large-scale commercial
manufacture of
modern compact laundry detergents. It should be understood that even
hydrolysis of I% by
weight of the surfactant paste can have major financial consequences in large-
scale
commercial manufacturing of detergent products.
Typical prior art attempts in this area involved immediately forming
surfactant
particles after the paste was manufactured. However, this requires "on-site"
particle
forrtxing equipment or requires the surfactant-making equipment to be housed
in or near the
detergent manufacturing facility. Currently, detergent-making and surfactant
paste-making
industries have become separated both physically as well as from a commercial
standpoint,
a trend which is only increasing. Thus, it would be desirable to have a high
active
surfactant paste which remains stable over longer periods of time so as to
enable the
surfactant-making operation to be located farther away from the detergent-
making facility
which is more representative of the current commercial environment.
Yet another challenge with the use of such high active surfactant pastes
involves
their rheological properties in that they must have a low enough viscosity to
be pumped in
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and out of transport trucks or trains and in and out of storage tanks at the
detergent
manufacturing facility. Any significant temperature changes may lead to
undesirable
gelling or solidification of the surfactant paste causing increases in
manufacturing expenses
and time. Note, however, that different rheological properties of the
surfactant paste may
result upon repeating.
Also in that regard, additional ingredients such as carbonates which are
included so
as to maintain the storage and transport stability of the surfactant paste
before it is
processed has the effect of increasing the viscoelasticity of the high active
surfactant paste,
therefore rendering it very difficult to process. The difficulty in processing
arises due to a
change in the viscoelasticity of the surfactant paste which requires
relatively expensive
high-pressure pumps, larger pipe lines and shorter transport distances to be
implemented
into the detergent-making process. As a consequence, it would be desirable to
have a
process in which the storage stability of the paste is maintained without
sacrificing its
processability.
1 S Accordingly, despite the above-mentioned disclosures in the art, there
remains a
need for a process for producing an agglomerated detergent composition from a
high active
surfactant paste which is sufficiently stable during transportation and
storage for sufficient
periods of time so as to enable large-scale commercial manufacture of modern
compact
detergent compositions. Also, there remains a need for such a process which is
inexpensive
and can be easily incorporated into large-scale production facilities for low
dosage or
compact detergents.
BACKGROUND ART
The following references are directed to surfactant pastes: Aouad et al, WO
93/18123 (Procter & Gamble); Aouad et al, WO 92/18602 (Procter & Gamble);
Aouad et
al, EP 508,543 (Procter & Gamble); Mueller et al, U.S. Patent no. 5,152,932;
Strauss et al,
U.S. Patent No. 5,080,848 (Procter & Gamble); Ofosu-Asante et al, U.S. Patent
No.
5,066,425 (Procter & Gamble); Jolicoeur et al, U.S. Patent No. 5,045,238
(Procter &
Gamble); and Van Zorn et al, EP 504,986 (Shell). 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 al, U.S. Patent
No. 5,108,646
(Procter & Gamble); Capeci et al, U.S. Patent No. 5,366,652 (Procter &
Gamble); Capeci et
al, U.S. Patent No. 5,486,303 (Procter & Gamble); Capeci et al, U.S. Patent
No. 5,489,392
(Procter & Gamble); Hollingsworth et al, European Patent Application 351,937
(Unilever);
and Swatling et al, U.S. Patent No. 5,205,958.
SUMMARY OF THE INVENTION
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The present invention meets the needs identified above by providing a process
for making
detergent agglomerates from a high active surfactant paste and a detergent
builder. There is a
significant advantage with this process in that the surfactant paste is
stable, pumpable, and
transportable over an extended period of time so as to facilitate mufti-
location, large-scale
manufacture of modern compact detergent products. In particular, the high
active surfactant paste
can be manufactured in one facility, and thereafter, stored and transported to
a remote facility for
further processing into the finished detergent agglomerates.
As used herein, the term "contaminants" means any foreign substance with which
the
surfactant paste comes into contact while being stored and transported prior
to the inputting and
agglomerating steps in the process. Examples of such contaminants include, but
are not limited to,
mufti-colored residue of sulfuric acid, sodium sulfate, fatty alcohol, iron,
chromium, and nickel.
As used herein with respect to the surfactant paste, the term "stable" means
that the surfactant
paste substantially retains its formulation which contains a neutralized
surfactant and has not
significantly reverted via hydrolysis back to its alcohol form. As used herein
with respect to the
surfactant paste, the term "processablc" means that the surfactant paste
retains desirable
rheological properties so as to allow it to be used in the current process
which typically means that
it will have a viscosity as detailed hereinafter with respect to the Power Law
Model. As used
herein, the term "agglomerates" refers to particles formed by agglomerating
detergent granules or
particles which typically have a smaller mean particle size than the formed
agglomerates. All
percentages and ratios used herein are expressed as percentages by weight
(anhydrous basis)
unless otherwise indicated. All viscosities referenced herein are measured at
70°C (~5°C) and at
shear rates of about 10 to 100 sec-' unless indicated otherwise.
In accordance with one aspect of the invention, a process for producing
detergent
agglomerates is provided. The process comprises the steps of: (a) providing a
non-linear
viscoelastic surfactant paste including, by weight of the surfactant paste,
from about 70% to 95%
of a detersive surfactant, from about 5°'i° to about 30% of
water, and an excess amount of an alkali
metal hydroxide such that the pH of the surfactant paste is at least about 10;
(b) regulating the
temperature of the surfactant paste within a range from about SO°C to
about 80°C so that the
surfactant paste is processable and stable for at least 48 hours; (c) charging
the surfactant paste into
a high speed mixer/densifier; (d) inputting from about 1% to about 70% by
weight of a detergency
builder into the high speed mixer/densifier; and (e) agglomerating the
surfactant paste and the
builder by treating the surfactant paste and the builder initially in the high
speed mixer/densifier at
about 300 rpm for from about 1 to about 30 seconds, and subsequently in a
moderate speed
mixer/densifier at from about 100 to about 300 rpm for from about .25 to about
10 minutes, so as
to form the detergent agglomerates having a density of at least 650g/ a .
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In accordance with a highly preferred aspect of the invention, another process
for
producing detergent agglomerates is provided. The process comprises the steps
of: (a)
providing a non-linear viscoelastic surfactant paste including, by weight of
the surfactant
paste, from about 70% to 80% of a mixture of C 14-15 alkyl sulfate surfactant
and C 12-13
linear alkylbenzene sulfonate surfactant, from about 15% to about 20% of
water, from about
2% to about 8% of polyethylene glycol and from about 0.5% to about 1% of
sodium
hydroxide such that the pH of the surfactant paste is at least about 11; (b)
regulating the
temperature of the surfactant paste within a range from about 65°C to
about 70°C so that the
surfactant paste is processable and stable for at least 120 hours;
(c) charging from about 1% to about 50% by weight of the surfactant paste into
a high speed
mixer/densifier; (d) inputting from about 1 % to about 70% by weight of a
detergency
builder into the high speed mixer/densifier; (e) agglomerating the surfactant
paste and the
builder by treating the surfactant paste and the builder initially in the high
speed
mixer/densifier and subsequently in a moderate speed mixer/densifier to form
the detergent
agglomerates; and (fj drying the detergent agglomerates. The present invention
also
provided detergent compositions comprising detergent agglomerates made in
accordance
with any of the processed described herein.
Accordingly, it is an object of the invention to provide a process for
producing an
agglomerated detergent composition from a high active surfactant paste which
is su~ciently
stable during transportation and storage for sufficiently extended periods of
time so as to
enable large-scale commercial manufacture of modern compact detergent
compositions. It
is also an object of the invention to provide such a process which is
inexpensive and can be
easily incorporated into large-scale production facilities for low dosage or
compact
detergents. 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
Generally, the present process is used in the production of low dosage
detergents,
whereby the resulting detergent agglomerates can be used as a detergent or as
a detergent
additive. In particular, the process can be used to form "high active" (i.e.
high surfactant
level) detergent agglomerates which are used as an admix for purposes of
enhancing the
active levels in granular low dosage detergents, and thereby, allow for more
compact
detergents.
Process
The process produces free flowing, high density detergent agglomerates,
preferably
having a density of at least 650 g/1. The process produces high density
detergent
agglomerates from a highly active and viscoelastic surfactant paste having a
relatively tow
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water content. In the past, processing and storing certain highly
viscoelastic, high active
surfactant pastes has been a problem, especially in light of their sensitivity
to temperature
variations and contaminants which are acidic in nature. While not intending to
be bound by
theory, it is believed that such temperature variations and acidic
contaminants cause the
autocatalytic hydrolysis reaction of the surfactant paste which effectively
reverts the
surfactant paste to an aqueous alcohol solution that cannot be reprocessed. It
has therefore
been found that optimally selected temperature ranges and pH ranges of
contaminants must
be regulated in order to produce the desired detergent agglomerates which are
used in
modern compact detergent products.
In the first step of the process, a non-linear viscoelastic surfactant paste
is provided
which is characteristic of many highly active, highly viscoelastic pastes used
in producing
high density detergent agglomerates. The phrase "nonlinear viscoelastic" means
that the
paste has a nonlinear fluid velocity profile and exhibits viscoelastic fluid
behavior, i.e. it
can be stretched during flow such as chewing gum or the like. Until now, such
nonlinear
viscoelastic surfactant pastes have been very difficult to process and keep
stable.
Preferably, the surfactant paste comprises, by weight of the surfactant paste,
from about
70% to about 95%, more preferably from about 70% to about 85%, and most
preferably
from about 70% to about 75%, of a detersive surfactant.
In a preferred embodiment, the surfactant paste is a mixture of C I4-15 alkyl
sulfate
("AS") and CI2-13 linear alkylbenzene sulfonate ("LAS") surfactants in a
weight ratio of
from about I:1 to about 5:1 (AS:LAS). Another preferred embodiment herein
contemplates a surfactant paste mixture having a weight ratio of C14-15 alkyl
sulfate to
C 12-13 linear alkylbenzene sulfonate of about 3:1. Other optional surfactant
systems
include pure AS or pure LAS surfactants in the paste as well as alkyl ethoxy
sulfate
("AES") systems in which AES is the sole or one of the surfactants in the
paste.
The surfactant paste also includes from about 5% to about 30%, more preferably
from about 15% to about 25%, and most preferably from about 15% to about 20%,
by
weight of the paste, of water. Additionally, the paste includes from about
0.1% to about
10%, more preferably from about 1% to about 8%, and most preferably from about
2% to
about 8%, by weight of the paste, of polyethylene glycol. The surfactant paste
also contains
from about 0.01 % to about 5%, more preferably from about 0.1 % to about 1 %,
and most
preferably from about 0.5% to about 1 %, by weight of the paste, of an alkali
metal
hydroxide which preferably is sodium hydroxide. Also included in the
surfactant paste are
minor ingredients such as unreacted alcohols, sulfates and the like, although
it is preferable
to keep these amounts to a minimum.
In the subsequent step of the process, the surfactant paste is regulated
within a
temperature range of from about 50°C to about 80°C, more
preferably from about 60°C to
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about 75°C, and most preferably from about 65°C to about
70°C. Preferably, the regulating
step maintains or renders the surfactant paste stable for at least 48 hours,
more preferably
for at least 72 hours, and most preferably for at least 170 hours. In this
way, the likelihood
of the surfactant paste undergoing the undesirable hydrolysis reaction and/or
being difficult
to transport and process due to unbearable rheological properties, such as
high viscosity, is
eliminated.
Furthermore, it is preferable that the surfactant paste be substantially free
of
materials which produces a gas when reacted with an acid. Such materials
include
carbonates, perearbonates, perborates or any other material which produces a
gas upon
contact with an acidic material. While not intending to be bound by theory, it
is
hypothesized that if the surfactant paste includes such a gas-producing
material, it will
react with any acidic contaminant material to produce a gas that propagates
through the .
remaining surfactant paste, thereby creating a "channel" or "path" through
which the acidic
contaminant can traverse the paste. This facilitates the hydrolysis reaction
of the entire
I S surfactant paste as opposed to onty a small isolated hydrolysis incident
which would not
otherwise affect the overall surfactant paste composition. Also in this
regard, it is
preferable in the current process to maintain the surfactant paste
substantially free of
contaminant materials having a pH of less than about 7.
In the next step of the process, the surfactant paste is charged into a high
speed
TM
mixer/densifier (e.g. LSdige Rxycler CB 30) which typically operates in 300
rpm to about
2500 rpm range. In this step, from about 25% to about 65%, mote preferably 30%
to about
60%, and most preferably from about 35% to about 55%, by weight of the
surfactant paste,
is used in the process to make the agglomerates. Also, from about I% to about
70%, more
preferably from about 5% to about 70~/° and, most preferably from about
50% to about 70%,
by weight of a detergency builder is inputted into the high speed
mixer/densifier. Although
other builders can be used in the process as described hereinafter,
aluminosiiicate builder is
tha preferred.
The surfactant paste and the builder are agglomerated by treating the paste
and the
builder initially in the high speed mixer/densifier and subsequently in a
moderate speed
TM
mixer/densifier (e.g. LBdige Recycler KM 300 "Ploughshare" having a large
central shaft
operating in the 100 rpm to 300 rpm range) so as to form detergent
agglomerates. Other
equipment suitable for use as the high speed mixer/densifier or moderate speed
mixer/densifier are described in Capeci, U.S. Patent 5,366,652. Optionally,
other
conventional detergent ingredients as described hereinafter can also be
inputted into
the high speed mixer/densifier and/or moderate speed mixer/densifier to make a
fully
formulated detergent agglomerate.
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The surfactant paste, builder and other optional starting detergent materials
are sent
to a moderate speed mixer/densifier for further build-up agglomeration
resulting in
agglomerates having a density of at least 650 g/1 and, more preferably from
about 700 g/1
to about 900 g/1. Preferably, the mean residence time of the surfactant paste
and other
TM
starting detergent materials in the high speed mixer/densifier (e.g. Lodige
Recycler CB 30
mixer/densifier) is from about I to 30 seconds while the residence time in low
or moderate
TM
speed mixer/densifier (e.g. Lodige Recycler KM 300 "Ploughshare"
mixer/densifier) is
from about 0.25 to 10 minutes.
Inevitably, a certain amount of the agglomerates exiting the moderate speed
mixer/densifier will be below the predetermined particle size range and
optionally, can be
separated and recycled back to the high speed mixer/densifier for further
build-up
agglomeration. In that regard, these so-called undersized agglomerates or
"fines" wilt
comprise from about 5% to about 30% by weight of the detergent agglomerates.
The particle porosity of the resulting detergent agglomerates produced
according to
the process of the invention is preferably in a range from about 5% to about
20%, more
preferably at about 10%. The combination of the abovo-rcfercnced porosity and
particle
size results in agglomerates having density values of 650 g/1 and higher. Such
a feature is
especially useful in the production of low dosage laundry detergents as well
as other
granular compositions such as dishwashing compositions.
The process can comprise the steps of spraying an additional binder in the
mixer/densifier(s) used in the agglomeration step to facilitate production of
the desired
detergent agglomerates. A binder is added for purposes of enhancing
agglomeration by
providing a "binding" or "sticking" agent for the detergent components. The
binder is
preferably selected from the group consisting of water, anionic surfactants,
nonionic
surfactants, polyethylene glycol, polyacrylates, citric acid and mixtures
thereof. Other
suitable binder materials including those listed herein are described in
Beerse et al, U.S.
Patent No. 5,108,646 (Procter & Gamble Co.),
Another optional step contemplated by the present process includes
conditioning
the detergent agglomerates by drying the detergent agglomerates after the
moderate speed
mixer/densifier. Yet another optional step involves adding a coating agent
(e.g.
aluminosilicates, carbonates, sulfates, or any other dry powdered material) to
the detergent
agglomerate before or after they exit the moderate speed mixer/densifier for
purposes of
enhancing the flowability of the agglomerates (i.e. reduce caking). This
furthers enhances
the condition of the detergent agglomerates for use as an additive or to place
them in
shippable or packagable form. Those skilled in the art will appreciate that a
wide variety of
methods may be used to dry as well as cool the exiting detergent agglomerates
without
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departing from the scope of the invention. By way of example, apparatus such
as a
fluidized bed can be used for drying while an airlift can be used for cooling
should it be
necessary.
Surfactant Paste
The viseoelastic surfactant paste used herein has viscoelastic fluid
properties which can
be described by a commonly used mathematical model that accounts for the shear
thinning nature
of the paste. The mathematical model is called the Power Law Model and is
described by the
following relation:
cr = K~
where a = Shear Stress (dynes/cm2), K = Consistency (Poise-secn' I ), y =
Shear Rate (sec' I ), and n
= Rate Index (dimensionless). The rate index n varies from 0 to 1. The closer
n is to 0, the more
shear thinning the fluid. The closer n is to I, the closer-it is to simple
Newtonian behavior, i.e.
constant viscosity behavior. K can be interpreted as the apparent viscosity at
a shear rate of 1 sec'
I S In this context, the viscoelastic surfactant paste used in the process has
a consistency K at
70°C of from about 50,000 to about 250,000 cPoisrsecn'I (500 to 2,500
Poisc~secn'1), more
preferably from about 100,000 to about 195,000 cPoise~secn'1 (1,000 to 1,950
Poise~secn'I), and
most preferably from about 120,000 to about 180,000 cPoise~secn'I (1,200 to
1,800 Poise-secn'I).
Preferably, the surfactant paste has a shear index n of from about 0.05 to
about 0.25, more
preferably from about 0.08 to about 0.20 and most preferably from about 0.10
to about 0.15.
The surfactant in the paste can be 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, Nonris, 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, avionics and nonionic are preferred and avionics are
most preferred.
The following are representative examples of detergent surfactants useful in
the
present surfactant paste. Water soluble salts of the higher fatty acids, i.e.,
"soaps", are
useful anionic surfactants in the compositions herein. This includes alkali
metal soaps such
as the sodium, potassium, ammonium, and alkylolammonium salts of higher fatty
acids
containing from about 8 to about 24 carbon atoms, and preferably from about 12
to about
18 carbon atoms. Soaps can be made by direct saponification of fats and oils
or by the
neutralization of free fatty acids. Particularly useful are the sodium and
potassium salts of
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the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium
or potassium
tallow and coconut soap.
Additional anionic surfactants which suitable for use herein include the water-
soluble salts, preferably the alkali metal, ammonium and alkylolammonium
salts, of
organic sulfuric reaction products having in their molecular structure an
alkyl group
containing from about 10 to about 20 carbon atoms and a sulfonic acid or
sulfuric acid ester
group. (Included in the term "alkyl" is the alkyl portion of acyl groups.)
Examples of this
group of synthetic surfactants are the sodium and potassium alkyl sulfates,
especially those
obtained by sulfating the higher alcohols (C8-18 carbon atoms) such as those
produced by
reducing the glycerides of tallow or coconut oil; and the sodium and potassium
alkylbenzene sulfonates in which the alkyl group contains from about 9 to
about 15 carbon
atoms, in straight chain or branched chain configuration, e.g., those of the
type described in
U.S. Patents 2,220,099 and 2,477,383. Especially valuable are linear straight
chain
alkylbenzene sulfonates in which the average number of carbon atoms in the
alkyl group is
from about 11 to 13, abbreviated as C11-13 LAS.
Other anionic surfactants suitable for use herein are the sodium alkyl
glyceryl ether
suifonates, especially those ethers of higher alcohols derived from tallow and
coconut oil;
sodium coconut oil fatty acid monoglyceride sulfonates and sulfates; sodium or
potassium
of ethylene oxide per molecule and wherein the alkyl groups contain from about
8 to about
12 carbon atoms; and sodium or potassium salts of alkyl ethylene oxide ether
sulfates
containing about 1 to about 10 units of ethylene oxide per molecule and
wherein the alkyl
group contains from about I O to about 20 carbon atoms.
In addition, suitable anionic surfactants include the water-soluble salts of
esters of
alpha-sulfonated fatty acids containing from about 6 to 20 carbon atoms in the
fatty acid
group and from about 1 to 10 carbon atoms in the ester group; water-soluble
salts of
2-acyloxyaikane-1-sulfonic acids containing from about 2 to 9 carbon atoms in
the acyl
group and from about 9 to about 23 carbon atoms in the alkane moiety; alkyl
ether sulfates
containing from about 10 to 20 carbon atoms in the alkyl group and from about
1 to 30
moles of ethylene oxide; water-soluble salts of olefin and paraffin sulfonates
containing
from about 12 to 20 carbon atoms; and beta-alkyloxy alkane sulfonates
containing from
about 1 to 3 carbon atoms in the alkyl group and from about 8 to 20 carbon
atoms in the
alkane moiety.
Preferred anionic surfactants are C10-18 linear alkylbenzene sulfonate and C10-
18
alkyl sulfate. If desired, low moisture (less than about 25% water) alkyl
sulfate paste can
be the sole ingredient in the surfactant paste. Most preferred aTe C10-18
alkyl sulfates,
linear or branched, and any of primary, secondary or tertiary. A preferred
embodiment of
the present invention is wherein the surfactant paste comprises from about 20%
to about
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WO 97/39100 PCT/US97/06484
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40% of a mixture of sodium C10-13 linear alkylbenzene sulfonate and sodium C12-
16
alkyl sulfate in a weight ratio of about 2:1 to 1:2. Another preferred
embodiment of the
detergent composition includes a mixture of C 10-18 alkyl sulfate and C 10-18
alkyl ethoxy
sulfate in a weight ratio of about 80:20.
Water-soluble nonionic surfactants are also useful in the instant invention.
Such
nonionic materials include compounds produced by the condensation of alkylene
oxide
groups (hydrophilic in nature) with an organic hydrophobic compound, which may
be
aliphatic or alkyl aromatic in nature. The length of the polyoxyalkylene group
which is
condensed with any particular hydrophobic group can be readily adjusted to
yield a
water-soluble compound having the desired degree of balance between
hydrophilic and
hydrophobic elements.
Suitable nonionic surfactants include the polyethylene oxide condensates of
alkyl
phenols, e.g., the condensation products of alkyl phenols having an alkyl
group containing
from about 6 to 15 carbon atoms, in either a straight chain or branched chain
configuration,
with from about 3 to 12 moles of ethylene oxide per mole of alkyl phenol.
Included are the
water-soluble and water-dispersible condensation products of aliphatic
alcohols containing
from 8 to 22 carbon atoms, in either straight chain or branched configuration,
with from 3
to 12 moles of ethylene oxide per mole of alcohol.
An additional group of nonionics suitable for use herein are semi-polar
nonionic
surfactants which include water-soluble amine oxides containing one alkyl
moiety of from
abut 10 to 18 carbon atoms and two moieties selected from the group of alkyl
and
hydroxyalkyl moieties of from about 1 to about 3 carbon atoms; water-soluble
phosphine
oxides containing one alkyl moiety of about 10 to 18 carbon atoms and two
moieties
selected from the group consisting of alkyl groups and hydroxyalkyl groups
containing
from about I to 3 carbon atoms; and water-soluble sulfoxides containing one
alkyl moiety
of from about 10 to 18 carbon atoms and a moiety selected from the group
consisting of
alkyl and hydroxyalkyl moieties of from about 1 to 3 carbon atoms.
Preferred nonionic surfactants are of the formula RI(OC2H4)nOH, wherein R1 is
a
C 10 C 16 alkyl group or a Cg C 12 alkyl phenyl group, and n is from 3 to
about 80.
Particularly preferred are condensation products of C 12 C 15 alcohols with
from about 5 to
about 20 moles of ethylene oxide per mole of alcohol, e.g., C 12 C 13 alcohol
condensed with
about 6.5 moles of ethylene oxide per mole of alcohol.
Additional suitable nonionic surfactants include polyhydroxy fatty acid amides
of the
formula
R-C-N-Z
CA 02251844 2000-11-O1
-12-
wherein R is a C9_ l7 alkyl or afkenyl, R l is a methyl group and Z is
glycityl derived from a
reduced sugar or alkoxylated derivative thereof. Examples are N-methyl N-1-
deoxyglucityl
cocoamide and N-methyl N-1-deoxyglucityl oleamide. Processes for making
polyhydmxy
fatty acid annides are known and can be found in Wilson, U.S. Patent No.
2.965,576 and
Schwartz, U.S. Patent No. 2,703,798.
Ampholytic surfactants include derivatives of aliphatic or aliphatic
derivatives of
heterocyclic secondary and tertiary amines in which the aliphatic moiety can
be straight
chain or branched and wherein one of the aliphatic substituents contains from
about 8 to 18
carbon atoms and at least one aliphatic substituent contains an anionic water-
solubilizing
group.
Zwitterionic surfactants include derivatives of aliphatic, quaternary,
ammonium,
phosphonium, and sulfonium compounds in which one of the aliphatic
substituents contains
from about 8 to 18 carbon atoms.
Cationic surfactants can also be included in the present invention. Cationic
surfactants comprise a wide variety of compounds characterized by one or more
organic
hydrophobic groups in the canon and generally by a quaternary nitrogen
associated with an
acid radical. Pentavaient nitrogen ring compounds are also considered
quaternary nitrogen
compounds. Suitable anions are halides, methyl sulfate and hydroxide. Tertiary
amines
can have characteristics similar to cationic surfactants at washing solution
pH values less
than about 8.5. A more complete disclosure of these and other cationic
surfactants useful
herein can be found in U.S. Patent 4,228,044, Cambre, issued October l4, 1980.
Cationic surfactants are often used in detergent compositions to provide
fabric
softening and/or antistatic benefits. Antistatic agents which provide some
softening benefit
and which are preferred herein are the quaternary ammonium salts described in
U.S. Patent
3,936,537, Baskerville, Jr. et al., issued February 3, 1976.
Deteraencv Builder
The present process includes the step of inputting a detergent builder into
the high
speed mixer/densifier to coagglomerate with the surfactant paste. The builder
also assists
in controlling mineral, especially Ca and/or Mg, hardness in wash water or to
assist in the
removal of particulate soils from surfaces. Builders can operate via a variety
of
mechanisms including forming soluble or insoluble complexes with hardness
ions, by ion
exchange, and by offering a surface more favorable to the precipitation of
hardness ions
than are the surfaces of articles to be cleaned. Builder level can vary widely
depending
upon end use and physical form of the composition. Built detergents typically
comprise at
CA 02251844 2000-11-O1
_13.
least about I % builder. Liquid formulations typically comprise about 5% to
about SO%,
more typically 5% to 35% of builder. Granular formulations typically comprise
from about
I 0% to about 80%, more typically I S% to 50% builder by weight of the
detergent
composition. Lower or higher levels of builders are not excluded. For example,
certain
detergent additive or high-surfactant formulations can be unbuilt.
Suitable builders herein can be selected from the group consisting of
phosphates and
polyphosphates, especially the sodium salts; silicates including water-soluble
and hydrous
solid types and including those having chain-, layer-, or three-dimensional-
structure as
well as amorphous-solid or non-structured-liquid types; carbonates,
bicarbonates,
sesquicarbonates and carbonate minerals other than sodium carbonate or
sesquicarbonate;
aluminosiiicates; organic mono-, di-, tri-, and tetracarboxylates especially
water-soluble
nonsurfactant carboxylates in acid, sodium, potassium or alkanolammonium salt
form, a~
well as oligomeric or water-soluble low molecular weight polymer carboxylates
including
aliphatic and aromatic types; and phytic acid. These may be complemented by
borates,
e.g., for pH-buffering purposes, or by sulfates, especially sodium sulfate and
any other
fillers or carriers which may be important to the engineering of stable
surfactant and/or
builder-containing detergent compositions.
Builder mixtures, sometimes termed "builder systems" can be used and typically
comprise two or more conventional builders, optionally complemented by
chelants, pH-
buffers or fillers, though these latter materials are generally accounted for
separately when
describing quantities of materials herein. In terms of relative quantities of
surfactant and
builder in the present detergents, preferred builder systems arc typically
formulated at a
weight ratio of surfactant to builder of from about 60:1 to about 1:80.
Certain preferred
laundry detergents have said ratio in the range 0.90:1.0 to 4.0:1.0, more
preferably from
0.95:1.0 to 3.0:1Ø
P-containing detergent builders often preferred where permitted by legislation
include, but are not limited to, the alkali metal, ammonium and
alkanolammonium salts of
polyphosphates exemplified by the tripolyphosphates, Pyrophosphates, glassy
polymeric
mete-phosphates; and phosphonates.
Suitable silicate builders include alkali metal silicates, particularly those
liquids
and solids having a Si02:Na20 ratio in the range 1.6:1 to 3.2: I, including,
particularly for
automatic dishwashing purposes, solid hydrous 2-ratio silicates marketed by PQ
Corp.
under the tradename BRITESIL~, e.g., Bftl.'ITSII ~ HzO; and layered silicates,
e.g., those
described in U.S. 4,664,839, May 12, 1987, H. P. R.ieck. NaSKS-6, sometimes
abbreviated
"SKS-6", is a crystalline layered aluminum-free S-Na2Si05 morphology silicate
marketed
by Hoechst and is preferred especially in granular laundry compositions. See
preparative
methods in German DE-A-3,417,649 and DE-A-3,742,043. Other layered silicates,
such as
CA 02251844 1998-10-15
WO 97/39100 PCTlUS97/06484
-14-
those having the general formula NaMSix02x+1'YH20 wherein M is sodium or
hydrogen,
x is a number from 1.9 to 4, preferably 2, and y is a number from 0 to 20,
preferably 0, can
also or alternately be used herein. Layered silicates from Hoechst also
include NaSKS-5,
NaSKS-7 and NaSKS-I I, as the a, (3 and y layer-silicate forms. Other
silicates may also be
useful, such as magnesium silicate, which can serve as a crispening agent in
granules, as a
stabilizing agent for bleaches, and as a component of suds control systems.
Also suitable for use herein are synthesized crystalline ion exchange
materials or
hydrates thereof having chain structure and a composition represented by the
following
general formula in an anhydride form: xM20.ySi02.zM'O wherein M is Na and/or
K, M' is
Ca and/or Mg; y/x is 0.5 to 2.0 and 7Jx is 0.005 to 1.0 as taught in U.S.
5,427,71 l,
Sakaguchi et al, June 27, 1995.
Suitable carbonate builders include alkaline earth and alkali metal carbonates
as.
disclosed in German Patent Application No. 2,321,001 published on November 15,
1973,
although sodium bicarbonate, sodium carbonate, sodium sesquicarbonate, and
other
1 S carbonate minerals such as trona or any convenient multiple salts of
sodium carbonate and
calcium carbonate such as those having the composition 2Na2C03.CaC03 when
anhydrous, and even calcium carbonates including calcite, aragonite and
vaterite, especially
forms having high surface areas relative to compact calcite may be useful, for
example as
seeds or for use in synthetic detergent bars.
Aluminosilicate builders are especially useful in granular detergents, but can
also
be incorporated in liquids, pastes or gels. Suitable for the present purposes
are those having
empirical formula: [Mz(A102)z(Si02h,]~xH20 wherein z and v are integers of at
least 6,
the molar ratio of z to v is in the range from 1.0 to 0.5, and x is an integer
from 15 to 264.
Aluminosilicates can be crystalline or amorphous, naturally-occurring or
synthetically
derived. An aluminosilicate production method is in U.S. 3,985,669, Krummel,
et al,
October 12, 1976. Preferred synthetic crystalline aluminosilicate ion exchange
materials
are available as Zeolite A, Zeolite P (B), Zeolite X and, to whatever extent
this differs from
Zeolite P, the so-called Zeolite MAP. Natural types, including clinoptilolite,
may be used.
Zeolite A has the formula: Nal2[(A102)12(Si02)12~'~20 wherein x is from 20 to
30,
especially 27. Dehydrated zeolites (x = 0 - 10) may also be used. Preferably,
the
aluminosilicate has a particle size of 0.1-10 microns in diameter.
Suitable organic detergent builders include polycarboxylate compounds,
including
water-soluble nonsurfactant dicarboxylates and tricarboxylates. More typically
builder
polycarboxylates have a plurality of carboxylate groups, preferably at least 3
carboxylates.
Carboxylate builders can be formulated in acid, partially neutral, neutral or
overbased form.
When in salt form, alkali metals, such as sodium, potassium, and lithium, or
alkanolammonium salts are preferred. Polycarboxylate builders include the
ether
CA 02251844 2000-11-O1
-1 S-
polycarboxylates, such as oxydisuecinate, see Berg, U.S. 3,128,287, April 7,
1964, and
Lamberti et al, U.S. 3,635,830, January 18, 1972; "TMSITDS" builders of U.S.
4,663,071,
Bush et al, May 5, 1987; and other ether carboxylates including cyclic and
aiicyclic
compounds, such as those described in U.S. Patents 3,923,679; 3,835,163;
4,158,635;
S 4,120,874 and 4,102,903.
Other suitable builders are the ether hydroxypolycarboxylates, copolymers of
malefic anhydride with ethylene or vinyl methyl ether-, 1, 3, 5-trihydroxy
benzene-2, 4, 6-
trisulphonic acid; carboxymethyloxysuccinic acid; the various alkali metal,
ammonium and
substituted ammonium salts of polyacetic acids such as ethylenediamine
tetraacetic acid
and nitrilotriacetic acid; as well as melGtic acid, succinic acid, polymaleic
acid, benzene
1,3,5-tricarboxylic acid, carboxymethyloxysuccinic acid, and soluble salts
thereof.
Citrates, e.g., citric acid and soluble salts thereof are important
carboxylate builders
e.g., for heavy duty liquid detergents, due to availability from renewable
resources and
biodegradability. Citrates can also be used in granular compositions,
especially in
combination with zeolite and/or layered silicates. Oxydisuccinates are also
especially
useful in such compositions and combinations.
Where permitted, and especially in the formulation of bars used for hand-
laundering operations, alkali metal phosphates such as sodium
tripolyphosphates, sodium
pyrophosphate and sodium orthophosphate can be used. Phosphonate builders such
as
ethane-1-hydroxy-l,l-diphosphonate and other known phosphonates, e.g., those
of U.S.
3,159,581; 3,213,030; 3,422,021; 3,400,148 and 3,422,137 can also be used and
may have
desirable antiscaling properties.
Certain detersive surfactant. or their short-chain homologs also have a
builder
action. For unambiguous formula accounting purposes, when they have surfactant
capability, these materials are summed up as detersive surfactants. Preferred
types for
builder functionality are illustrated by: 3,3-dicarboxy-4-oxa-1,6-
hexanedioates and the
related compounds disclosed in U.S. 4,566,984, Bush, January 28, 1986.
Succinic acid
builders include the CS-C2p alkyl and alkenyl succinic acids and salts
thereof. Succinate
builders also include: laurylsuccinutte, myristylsuccinate, palmitylsuccinate,
2-
dodecenylsuccinate (preferred), 2-pantadecenylsuccinate, and the like. Lauryl-
succinates
are described in European Patent Application 0,200,263, published November
5, 1986. Fatty acids, e.g., C 12-C 1 g monocarboxylic acids, can also be
incorporated into the
compositions as surfactant/buildes materials alone or in combination with the
aforementioned builders, especially citrate and/or the succinate builders, to
provide
additional builder activity. Other suitable polycarboxylates arc disclosed in
U.S. 4,144,226,
Crutchfield et al, March 13, 1979 and in U.S. 3,308,067, Diehl, March 7, 1967.
See also
Dieht, U.S. 3,723,322.
CA 02251844 2000-11-O1
-16-
Optionally, inorganic builder materials can be used which have the formula
(Mx)i
Cay (C03)z wherein x and l are integers from 1 to 15, y is an integer from l
to 10, z is an
integer from 2 to 25, Mi are cations, at least one of which is a water-
soluble, and the
equation Ei =_ 1 _ 15(xi multiplied by the valence of Mi) + 2y = 2z is
satisfied such that the
formula has a neutral or "balanced" charge. Waters of hydration or anions
other than
carbonate may be added provided that the overall charge is balanced or
neutral. The charge
or valence effects of such anions should be added to the right side of the
above equation.
Preferably, there is present a water-soluble cation selected from the group
consisting of
hydrogen, water-soluble metals, hydrogen, boron, ammonium, silicon, and
mixtures
thereof, more preferably, sodium, potassium, hydrogen,,iithium, ammonium and
mixtures
thereof, sodium and potassium being highly preferred. Nonlimiting examples of
noncarbonate anions include those selected from the group consisting of
chloride, sulfate,
fluoride, oxygen, hydroxide, silicon dioxide, chromate, nitrate, borate and
mixtures thereof.
Preferred builders of this type in their simplest forms are selected from the
group consisting
I S of Na2Ca(C03~, K2Ca(C03~, Na2Ca2(C03)3, NaKCa(C03~, NaKCa2(C03)3,
K2Ca2(C03)3, and combinations thereof. An especially preferred material for
the builder
described herein is Na2Ca(C03~ in any of its crystalline modifications.
Suitable builders
of the above-defined type are further illustrated by, and include, the natural
or synthetic
forms of any one or combinations of the following minerals: Afghanite,
Andersonite,
AshcroftineY, Beyer~ite, Borcarite, Burbankite, Butschliite, Cancrinite,
Carbocernaite,
Carletonite, Davyne, DonnayiteY, Fairchiidite, Ferrisurite, Franzinite,
Gaudefroyite,
Gaylussite, Girvasite, Gregoryite, Jouravskite, KamphaugiteY, Kettnerite,
Khanneshite,
LepersonniteGd, Liottite, MekelveyiteY, Microsommite, Mroseite,
Natrofairchildite,
Nyerereite, RernonditeCe, Sacrofanite, Schrockingerite, Shortite, Surite,
Tunisite,
Tuscanite, Tyrolite, Vishnevite, and Zemkorite. Preferred mineral forms
include Nyererite,
Fairchildite and Shortite.
Optional Detergent Components
The starting or entering detergent components in the present process can also
include
any.number of additional ingredients. These include other detergency builders,
bleaches,
bleach activators, sues boosters or suds suppressocs, 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,
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 .
CA 02251844 2000-11-O1
-17-
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 examples, which are intended to be illustrative only and
not
intended to be limiting in scope.
CA 02251844 2000-11-O1
-18-
EXAMPLE
This Example illustrates the process invention described and claimed herein.
The
percentages are on a weight basis, in the mixes prior to any subsequent follow-
up drying,
unless other wise specified. The terms "LAS" and "AS" as used herein mean,
respectively,
"sodium linear alkylbenzene sulfonate" and "sodium alkyl sulfate." Several
surfactant
pastes consisting of Ct4-tsAS ~d C12.3 LAS are made by sulfating Ct4.ts
alcohol with
S03 and co-neutralizing with CtZ.3HLAS using 50% caustic soda (sodium
hydroxide). The
specific compositions of the surfactant pastes are set forth in Table I.
Table I
Component A B ~ D E
Ct~ts alkyl sulfate 55.0 55.0 44.0 64.5 55.0
Ct2.3 linear alkylbenzene18.3 18.3 29.3 8.8 18.3
sulfonate
Polyethylene Glycol 4000 3.7 3.7 3.7 3.7 0.0
Sodium Hydroxide 0.75 0.5 0.75 0.75 0.75
~
Water 19.5 19.5 19.5 19.5 23.2
Minors (sulfate, unreacted,? 75 ~,Q 2.75 2.75 2.75
etc.)
Total 100 100 100 100 I 00
A falling film S03 reactor is used to prepare the acid form of Ct4.ts alkyl
sulfate and Ct2.3
linear alkylbenzene sulfonate. The acid is fed to a high active neutralization
system which
consists of a recycle loop containing a heat exchanger for cooling, a
recirculation pump
suitable for highly viscous fluids, and a high shear mixer with which the
reactants are
introduced. Surfactant paste exiting the high active neutralization system is
transported and
l 5 stored in jacketed, temperature-controlled 316L stainless steel storage
vessels at a
temperature of 7I °C. The surfactant paste remains stable and maintains
a pH above 10 for
at least five days (120 hours). The temperature of the paste is maintained
between 65°C to
about 70°C by ttte circulation of glycol solution through the vessel
jacketing.
Two feed streams of various detergent starting ingredients are continuously
fed, at
TM
a rate of 2800 kg/hr, into a Lodige CB-30 mixer/densifier, one of which
comprises the
surfactant paste and the other stream containing the detergent builder which
is
aluminosilicate. The surfactant paste, aluminosilicate and optional co-
b~uilder sodium
carbonate are agglomerated to form detergent agglomerates. The detergent
agglomerates
TM TM
from the Lodige CB-30 mixer/densifier are continuously fed into a Lddige KM-
600
mixer/densifier for further agglomeration. The resulting detergent
agglomerates are then
fed to optional conditioning apparatus including a fluid bed dryer and a fluid
bed cooler.
The detergent agglomerates exiting the fluid bed cooler are screened, after
which adjunct
detergent ingredients are admixed therewith to result in a fully formulated
detergent
product having a uniform particle size distribution.
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WO 97/39100 PCT/US97/06484
-19-
The composition of the detergent agglomerates exiting the fluid bed cooler is
set
forth in Table II below:
Table II
Comeonent % Weight
C~4-~s alkyl sulfate and C~2,3 linear alkylbenzene sulfonate 30.0
Aluminosilicate 36.0
Sodium Carbonate 21.0
Misc. (water, perfume, etc.) 13.0
Total ~ 100.0
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.
