a~~.~~~~~
- 1 - C3361
DETERGENT COMPOSITIONS
AND PROCESS FOR PREPARING THEM
TECHNICAL FIELD
The present invention relates to granular detergent
compositions and components of high bulk density, arid
their preparation by a dry neutralisation process.
BACKGROUND AND PRIOR ART
Recently there has been considerable interest within
iS the detergents industry in the production of detergent
powders having relatively high bulk~denssty,~-.Fon .example,
v '65'.0 g./.~litre v and vabove. ;I't hee ~ been ~sugg~sted rbh~at -:such
powders containing anionic surfactants,, for~example alkyl
benzene sulphonate, may be prepared by methods involving
in-situ neutralisation of an acid precursor of the
anionic surfactant with an alkali such as sodium
hydroxide or sodium carbonate.
CA 02034244 1999-09-13
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For examp:Le, JP 60 072 999A (Kao) and GB 2 166 452B
(Kao) disclose a process in which detergent sulphonic
acid, sodium carbonate and water are mixed in a strongly
shearing apparatus; the solid mass obtained is cooled to
40'C or below and pulverised; and the fine powder thus
obtained is granulated. This process is typical of those
disclosed in the art in that the product of the
neutralisation reaction is a doughy mass, and the
reaction requires apparatus such as kneader with a very
high energy requirement; and separate pulverisation and
granulation steps in different apparatus are required in
order to obtain an acceptable granular detergent product.
There has also been considerable recent interest in
the use of high-speed mixer/granulators in the
preparation of high-bulk-density detergent powders. For
example, EP 158 419B (Hashimura) discloses a process in
which nonionic surfactant and soda ash are mixed and
granulated in a reactor having horizontal and vertical
blades rotating at different speeds, to give a detergent
powder built with sodium carbonate and containing a high
level of nonionic surfactant.
GB 1 404 317 (Bell) discloses the preparation of a
detergent powder of low or moderate bulk density by a dry
neutralisation process. Detergent sulphonic acid is mixed
with an excess of soda ash in the presence of sufficient
water to initiate the neutralisation reaction but not
enough to wet the resultant product, which is in the form
of a free-flowing powder. The process is carried out in
apparatus, for example a ribbon blender, planetary mixer
or air transfer mixer, in which the reactants are "tossed
and fluffed", and carbon dioxide liberated during the
neutralisation is entrapped in the product particles. The
CA 02034244 1999-09-13
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process is thus directed towards the production of light,
porous particles comparable to those obtained by spray-
drying.
GB 1 369 :269 (Colgate) discloses a process for the
production of anionic detergent, by vigorously mixing
detergent sulphonic acid with powdered sodium carbonate
in a mixer with a cutting arrangement, for example a
Lodige ploughshare mixer. In order to obtain a granular
product rather than a doughy mass, it is necessary to
blow the detergent sulphonic acid in by means of a gas
stream, to ensure adequate fluidisation and mixing of the
reactants: this requires quite complex modification of
the mixer. The reaction apparently proceeds slowly and
produces a relatively coarse product requiring an
additional size reduction step.
US 4 690 '785 (Witco) discloses a process for the
production of alkylbenzene sulphonate powder by the
neutralisation of alkylbenzene sulphonic acid with a base
in solid or so:Lution form. A substantial amount of water
is present at the beginning of the process, and the heat
generated by the exothermic reaction is used to drive off
this, and the water generated by the reaction itself;
reaction temperatures of about 100'C are typical.
EP 352 135A (Unilever), published on 24 January
1990, relates to a process for the production of free-
flowing detergent powders and detergent powder components
of high bulk density and small particle size by dry
neutralisation at relatively low temperatures using only
a single piece of apparatus: a high-speed
mixer/granulator having both a stirring action and a
CA 02034244 1999-09-13
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cutting action. Maintenance of a temperature not higher
than 55'C throughout the neutralisation step is stated to
be essential; :if necessary, cryogenic cooling may be
employed.
The present inventors have now surprisingly
discovered that, with improved control of other process
parameters, this process can be carried out successfully
- or even advantageously - without the need for cooling
to temperatures not exceeding 55'C throughout the
neutralisation step.
Our copending Canadian Patent Application No.
2,026,156 describes and claims a process for the
continuous preparation of a granular detergent
composition of high bulk density, involving the
continuous dry neutralisation of a liquid anionic
surfactant precursor such as linear alkylbenzene
sulphonic acid in a high-speed mixer such as the LSdige
CB 30 Recycler, which contains a central horizontal
stirring axis but no separate cutting elements.
Neutralisation and granulation take place completely
during a very short residence period in the Recycler, and
the reaction mixture then passes continuously to a
moderate-speed mixer/granulator such as the LZidige KM 300
ploughshare mixer, where the residence time is longer,
for densificat:ion.
CA 02034244 1999-09-13
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DEFINITION OF THE INVENTION
The present invention provides a batch process for
the preparation of a granular detergent composition or
component having a bulk density of at least 650 g/litre,
which process includes the step of neutralising a liquid
acid precursor of an anionic surfactant with a solid
water-soluble alkaline inorganic material, the process
being characterised by the steps of:
(i) fluidising a particulate solid water-soluble
alkaline inorganic material in an amount in excess of
that required :for neutralisation, optionally in admixture
with one or more other particulate solids, in a high-
speed mixer/granulator having both a stirring action and
a cutting action;
(ii) adding the acid precursor to the high-speed
mixer/gra.nulator, without maintaining a temperature of
55'C or below, whereby neutralisation of the acid
precursor by the water-soluble alkaline inorganic
material occurs while the mixture remains in particulate
form;
(iii) granulating the mixture in the high-speed
mixer/granulator, in the presence of a liquid binder,
whereby a granular detergent composition or component
having a bulk density of at least 650 g/litre is formed.
The invention also provides a granular detergent
composition or component prepared by this process.
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The subject of the invention is the preparation of
high-bulk-density detergent powder by a batch process
involving the dry neutralisation of the acid precursor of
an anionic surfactant with an alkaline solid. The process
is carried out batchwise in a high-speed mixer/granulator
and involves the previously defined process steps (i),
(ii) and (iii) .
A very important characteristic of the process of
the invention is that the reaction mixture remains
throughout in particulate or granular form. Caking,
balling and dough formation are avoided, and the product
at the end of the granulation step needs no further
particle size :reduction. The process of the invention
generally produces a granular product containing at least
50 wt~, preferably at least 70 wt~, of particles smaller
than 1700 ).lm. This is achieved by ensuring that liquid
components, particularly the acid anionic surfactant
precursor, do not have an opportunity to act as binders
or agglomerating agents.
First, step (i) ensures that there is initially a
large amount of particulate solids present, relative to
the liquids to be added, in the mixer before the
introduction of the liquids. Preferably the total solids
present in step (i) amount to at least 60 wt~, more
preferably at :Least 67 wt~, of the total composition
present in step (ii). It is therefore advantageous to add
as high a proportion as possible of the solid ingredients
of the final product at this stage.
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_ 7 _
The solids must of course include a particulate
water-soluble .alkaline inorganic material (neutralising
agent), in at least slight excess over the amount
required for neutralisation. The terms "particulate solid
water-soluble alkaline inorganic material" and
"neutralising agent" used herein of course include
combinations of two or more such materials. If the
neutralising agent is a material that itself can play a
useful role in the final composition, substantially
larger amounts than this may be used.
According to a preferred embodiment of the invention
the neutralising agent comprises sodium carbonate, either
alone or in admixture with one or more other particulate
water-soluble alkaline inorganic materials, for example,
sodium bicarbonate and/or sodium silicate. Sodium
carbonate is o.f course also useful as a detergency
builder and provider of alkalinity in the final
composition. This embodiment of the invention may thus
advantageously be used to prepare detergent powders in
which sodium carbonate is the sole or principal builder,
and in that case substantially more sodium carbonate than
is required for neutralisation may be present.
The sodium carbonate embodiment of the invention is
also suitable, however, for the preparation of detergent
compositions in which substantial amounts of other
builders are present. Those other builders may also
advantageously be present in the high-speed
mixer/granulator in step (i). Examples of such builders
include crystalline and amorphous alkali metal
aluminosilicates, alkali metal phosphates, and mixtures
thereof. Sodium carbonate may nevertheless be present in
excess of the amount required for neutralisation, in
order to provide alkalinity in the product: an excess of
about 10 to 15 wt~ is then suitable.
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- 8 - C3361
The solids present in step (i) may also include any
other desired solid ingredients, for example,
fluorescers; polycarboxylate polymers; antiredeposition
agents, for example, sodium carboxymethyl cellulose; or
fatty acids for in-situ neutralisation to form soaps.
If desired, solid particulate surfactants, for
example, alkylbenzene sulphonate and/or alkyl sulphate in
powder form, may form part of the solids charge in step
(i). Thus, for example, a detergent powder prepared by ,
the process of the invention may contain alkylbenzene
sulphonate in part introduced as a powder in step (i),
and in part prepared in situ in step (ii).
Alternatively or additionally, a spray-dried
detergent base powder may form part of the solids charge
in step (i).
It is an important feature of the process of the
invention that the solids be very efficiently mixed and
fluidised before the introduction of any liquid
ingredients: the term "fluidisation" as used herein
means a state of mechanically induced vigorous agitation
in which the mass of particles is to some extent aerated,
but does not necessarily imply the blowing in of a gas.
This state is achieved by the choice of apparatus: a
high-speed mixer/granulator having both a stirring action
and :a. cutting <<acti~ov. Preferably he high-speed
mixer./.granu'latnr has rotatable-stirrer;~and:cutt.er
elements that can be operated independently of one
another, and at separately changeable or variable speeds.
Such a mixer is capable of combining a high-energy
stirring input with a cutting action, but can also be
used to provide other, gentler stirring regimes with or
without the cutter in operation.
CA 02034244 1999-09-13
_ g _
A preferred type of high-speed mixer/granulator for
use in the process of the invention is bowl-shaped and
preferably has a substantially vertical stirrer axis.
Especially preferred are mixers of the Fukae (Trade
Mark) FS-G series manufactured by Fukae Powtech Kogyo
Co., Japan; this apparatus is essentially in the form of
a bowl-shaped vessel accessible via a top port, provided
near its base with a stirrer having a substantially
vertical axis, and a cutter positioned on a side wall.
The stirrer and cutter may be operated independently of
one another, and at separately variable speeds. If
necessary, the vessel can be fitted with a cooling
jacket.
Other similar mixers found to be suitable for use in
the process of the invention include the Diosna (Trade
Mark) V series ex Dierks & Sohne, Germany; and the Pharma
Matrix (Trade Mark) ex T K Fielder Ltd., England. Other
mixers believed to be suitable for use in the process of
the invention are the Fuji (Trade Mark) VG-C series ex
Fuji Sangyo Co., Japan; and the Roto (Trade Mark) ex
Zanchetta & Co srl, Italy.
Yet another mixer found to be suitable for use in
the process of the invention is the Lodige (Trade Mark)
FM series batch mixer ex Morton Machine Co., Ltd.,
Scotland. This differs from the mixers mentioned above in
that its stirrer has a horizontal axis. This
configuration, however, has the disadvantage that mixing
and fluidising in step (i) is less efficient, and may
need to be supplemented by the blowing in of gas as
described in the aforementioned GB 1 369 269 (Colgate).
~;~~~~~
- 10 - 03361
Step (ii) of the process of the invention is the
introduction of the acid surfactant precursor. The way
in which this step is conducted is crucial to the success
of the process. In particular, it is believed to be
critical to ensure throughout the neutralisation step
that any liquid components do not have the opportunity to
cause substantial agglomeration.
Initial work on the present process, with control of
the temperature during step (ii) to 55°C or below,
indicated that the solids, efficiently fluidised by the
action of the mixer, had to be wetted with just
sufficient water to initiate and promote the
neutralisation reaction before they encountered the acid
precursor. The amount of free water present in step (ii)
was therefore believed to be very important, the term
"free water" being used to mean water not firmly bound as
water of hydration or crystallisation to inorganic
materials. It was believed that, if insufficient free
water were present, the reaction would not proceed
rapidly, and unreacted detergent acid precursor would
accumulate in the mixer and act as a binder, causing
substantial agglomeration, balling up and even dough
formation. Addition of a carefully controlled amount of
water at the neutralisation stage was therefore
considered an important part of the process as then
conceived. That combination of temperature control and
,process wat,er..control formed 'the ~=bas.i~s of .the
above-men~:z:br~~ed ~:p :35'2 T3'5A. y:(Unilever j .
It has now been found, at least when a crystalline
alkali metal aluminosilicate is present as part of the
solids charge, that the process may advantageously be
carried out without any addition of water at the
neutralisation stage, and without control of the
~:~~~~ ~4
- 11 - C3361
temperature throughout the neutralisation stage to <55°C.
When aluminosilicate is present, preferably no water is
added earlier than to the granulation stage (iii).
Another important process parameter is the manner of
addition of the acid precursor to the high-speed
mixer/granulator in step (ii). It would appear that the
rate and manner of addition should be such that the acid
precursor will be consumed immediately and will not
accumulate in the mixer in unreacted farm. It is
preferred that the acid precursor be introduced
gradually, rather than in a single, substantially
instantaneous addition, into the high-speed
mixer/granulator.
The actual time required and preferred for addition
of the acid precursor is of course dependent on the
amount to be added. It was initially thought that very
gradual addition over a period of at least 1 minute, and
preferably longer, was necessary, but it has subsequently
been found, following the optimisation of other process
variables (moisture content, powder mixing efficiency,
powder temperature), that rapid addition over a period of
less than 1 minute is also possible and may even be
preferred. Another measure that can be used to reduce
the addition time is the use of more than one manifold,
for example, two, for the introduction of the acid
precursor, .'so~,-;thavt. '.it °is : ii'mt~roduc2d ~s,zmu:ltaneously W
to
two or more"vdifferent locations within the'hsigh,-,spEed
mixer/granulator. Addition of the acid is thus still
preferably "gradual" in the sense that it should be added
in such a way that high local concentrations should be
avoided, either by spreading addition out over time, or
over space, or both.
l~i~a.~~
- 12 - C3361
The addition time may accordingly range, for
example, from 0.5 to 12 minutes, and a time of from 1 to .
20 minutes, more especially a time of from 1 to 3
minutes, is presently preferred.
The speed at which acid precursor is introduced into
the mixer may also be expressed as a rate of addition.
For a batch size of 750 kg, a rate of linear
alkylbenzenesulphonic acid of from 80 to 200 kg/min,
especially 100 to 140 kg/min, has been found to give good
results.
Other liquid detergent ingredients may be introduced
during step (ii). Examples of such ingredients include
nonionic surfactants, and low-melting fatty acids which
may be also be neutralised in situ, to form soaps.
The neutralisation step (ii) may typically take from
0.5 to 12 minutes, and, as indicated above, the addition .
of the acid precursor (optionally plus other liquid
ingredients) may or may not be preceded by a separate
step in which water (optionally plus other liquid
ingredients) is added to the mixer.
As indicated previously, the temperature of the
powder mass in the high-speed mixer/granulator need not
be maintained throughout step (ii) at 55°C or below, as
previously thought, i:n orde.r toavoid agglomeration and
lump ' f:ormaa:i:on: r :':~'he neutral~isa~t.ion te~p can therefore be
carried out successfully at temperatures~above't5'5°C.
Preferably, however, the temperature is not allowed to.
exceed 100°C, in order that excessive moisture loss may
be avoided; more preferably, the temperature does not
exceed 75°C.
~~a~~~~i~~
- 13 - C3361
The temperature of the reaction mixture of course
rises during the neutralisation step owing to the
exothermicity of the reaction, the amount of the increase
depending on the proportion of acid precursor in the
mixture; for example, it has been found that in the
preparation of a composition containing about 25 wt%
alkylbenzene sulphonate, as described in the, Example
below, the temperature typically rises to about 35°C
above ambient, ie about 55-55°C. There would appear to
be no advantage in operating at a temperature above that
occurring naturally. Generally, a temperature within the
range of from above 55°C to 75°C, preferably from above
55°C to 70°C, appears to be suitable. If desired, a
water-jacket may be used to provide temperature
control.
A very important feature of the process of the
invention is granulation in the high-speed
mixer/granulator. This will generally take the form of a
separate granulation step (iii) after addition of the
acid precursor and neutralisation are complete. When
operating at higher temperatures, however, granulation
can sometimes start to occur before neutralisation is
complete, and steps (ii) and (iii) of the process may
then be regarded as having coalesced to form a single
continuous step (ii)/(iii).
The granulation or densifucationv,,proc.~ss leads ao a
;product of yer~ ~' ~h~igh; 'bu3.3~ ::densvi~ty . t When working ;pat :l~oaaer
,;
temperatures (the process of EP' 352 13'5A) it 'was found
that granulation required the presence of a liquid
binder, but in an amount significantly lower than that
used when granulating a powder in conventional apparatus
such as a pan granulator. The binder, added prior to
granulation but after neutralisation was complete, would
~o~~~~i~~
- 14 - C3361
generally comprise water and/or a liquid detergent
ingredient, for example, an aqueous solution of a
polycarboxylate polymer, or a nonionic surfactant, or a
mixer of any of these. It has now been found that
addition of binder for step (iii) is not essential, and
that instead the temperature may be allowed to rise to
effect granulation. It may still be convenient,
however, to introduce liquid ingredients such as nonionic
surfactant at this stage, and then a lower granulation
temperature can be used.
During steps (i), (ii) and (iii) of the process of
the invention, the stirrer and cutter elements of the
high-speed mixer/granulator are preferably operated at
high speed to provide the most efficient mixing possible
and to maintain the reaction mixture in particulate form.
The stirrer speed thoughout these steps may suitably lie
within the range of from 60 to 150 rpm, preferably from
80 to 120 rpm, and the cutter speed within the range of
from 1000 to 3000 rpm. The preferred stirrer and cutter
speeds will, however, depend on the batch size and are
also subject to machine limitations: for example, the
Fukae FS-1200 mixer, which is suitable for processing a
750 kg batch, has a maximum stirrer speed of 100 rpm and
a maximum cutter speed of 2000 rpm, so that the preferred
stirrer speed range is cut down to 60-loo rpm, and the
preferred cutter speed range to 1000-2000 rpm. Smaller
machines, such , as' the FS-30., suita~b3:e .for ,pracess~ing a 15
~ kg ~bat~h, c-anaprovide'higher maximum speeds.
The product of the granulation step (iii) is a
particulate solid of high bulk density: at least 650
g/litre, preferably at least 750 g/litre, and more
preferably at least 800 g/litre. As previously
indicated, the particle size distribution is generally
CA 02034244 1999-09-13
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such that at least 50 wt~, preferably at least 70 wt~ and
more preferably at least 85 wt~, of particles are smaller
than 1700 dun, and the level of fines (particles <180 Eim)
is low. No further treatment has generally been found to
be necessary to remove either overside particles or
fines.
Although the product generally has good flow
properties, low compressibility and little tendency
towards caking, those powder properties may be improved
further and bulk density further increased by the
admixture of a finely divided particulate flow aid after
granulation is complete. Depending on the flow aid
chosen, it may suitably be added in an amount of form 0.2
to 12.0 wt~, b<~sed on the total product.
During addition of the flow aid, the stirrer speed
may advantageously be reduced, for example, to 60-80 rpm,
and the cutter is preferably not employed. Comminution of
the particles :is to be avoided if possible at this stage.
Suitable :flow aids include crystalline and amorphous
alkali metal aluminosilicates having an average particle
size within they range of from 0.1 to 20 Elm, preferably
from 1 to 10 ~,Irn. The crystalline material (zeolite) is
preferably addE~d in an amount of from 3.0 to 12.0 wt~,
more preferabl~r from 4.0 to 10.0 wt~, based on the total
product. The arnorphous material, which is more weight-
effective, is preferably added in an amount of from 0.2
to 5.0 wt~, more preferably from 0.5 to 3.0 wt~, based on
the total product. A suitable amorphous material is
available commercially from Crosfield Chemicals Ltd.,
Warrington, Chesshire, England, under the
CA 02034244 1999-09-13
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trade mark Alusil. If desired, both crystalline and
amorphous aluminosilicates may be used, together or
sequentially, as flow aids.
Other flow aids suitable for use in the process of
the invention include precipitated silica, for example,
Neosyl (Trade :Mark), and precipitated calcium silicate,
for example, Microcal (Trade Mark), both commercially
available from Crosfield Chemicals Ltd.
A process which comprises admixing finely divided
amorphous sodium aluminosilicate to a dense granular
detergent composition containing surfactant and builder
and prepared and/or densified in a high speed
mixer/granulator is described and claimed in EP 339 996A
(Unilever).
As already indicated, the process of the invention
produces a granular high-bulk-density solid, containing
surfactant and builder, and having a bulk density of at
lest 650 g/litre and preferably at least 700 g/litre. It
is also characi:erised by an especially low particle
porosity, preferably not exceeding 0.25 and more
preferably not exceeding 0.20, which distinguishes it
from even the densest powders prepared by spray-drying.
This fina:L granulate may be used as a complete
detergent composition in its own right. Alternatively,
it may be admixed with other components or mixtures
prepared separately, and may form a major or minor part
of a final product. Generally, any additional
;~~~~~~~
- 17 - C3361
ingredients such as enzymes, bleach and perfume that are
not suitable for undergoing the granulation process and
the steps that precede it may be admixed to the granulate
to make a final product. The densified granulate may
typically constitute from 40 to 100 wt% of a final
product.
In another embodiment of the invention, the
densified granulate prepared in accordance with the
l0 present invention is an "adjunct" comprising a relatively
high level of detergent-active material on an inorganic
carrier; and this may be admixed in a minor amount with
other ingredients to form a final product.
The process may with advantage be used to prepare
detergent compositions containing from 5 to 35 wt%, or
more, of anionic surfactant, this anionic surfactant
being derived wholly or in part from the in-situ
neutralisation reaction of step (ii).
The anionic surfactant prepared at least in part by
in-situ neutralisation may, for example, be selected from
linear alkylbenzene sulphonates, alpha-olefin
sulphonates, internal olefin sulphonates, fatty acid
ester sulphonates and combinations thereof. The process
of the invention is especially useful for producing
compositions containing alkylbenzene sulphonates, by
in-Situ neutral.isat'ion of ;the eQrrespond'ir~g a'Tkvlbenzene
su:lproni.c acid.
Other anionic surfactants that may be present in
compositions prepared by the process of the invention
include primary and secondary alkyl sulphates, alkyl
ether sulphates, and dialkyl sulphosuccinates. Anionic
ew~a~~i~~
- 18 - C3361
surfactants are of course well known and the skilled
reader will be able to add to this list by reference to
the standard textbooks on this subject.
As previously indicated, nonionic surfactants may
also be present. These too are well known to those
skilled in the art, and include primary and secondary
alcohol ethoxylates.
Other types of non-soap surfactant, for example,
cationic, zwitterionic, amphoteric or semipolar
surfactants, may also be present if desired. Many
suitable detergent-active compounds are available and are
fully described in the literature, for example, in
"Surface-Active Agents and Detergents", Volumes I and II,
by Schwartz, Perry and Berch.
If desired, soap may also be present, to provide
foam control and additional detergency and builder power.
Typically, detergent compositions produced by the
process of the invention may comprise form 10 to 35 wt%
of anionic surfactant, from 0 to 10 wt% of nonionic
surfactant, and from 0 to 5 wt% of fatty acid soap.
Typical products of the invention
The v~following ~.a~re general,:; ,v:r~an-limiting examples =of
formulation types that mayreadily be prepared by the
process of the invention.
~;~~~~.~~
- 19 - C3361
(1) Compositions containing crystalline or amorphous
alkali metal aluminosilicate, especially crystalline
zeolite and more especially zeolite 4A, as a detergency
builder:
(a) from 5 to 35 wt% of non-soap detergent-active
material consisting at least partially of anionic
surfactant,
(b) from 15 to 45 wto (anhydrous basis) of
crystalline or amorphous alkali metal
aluminosilicate,
and optionally other detergent ingredients, including any
excess of the neutralising agent for the anionic
surfactant, to 100 wt%. The weight ratio of (b) to (a)
is preferably at least 0.9:1.
An especially preferred class of detergent
compositions that may be prepared by the process of the
invention is described and claimed in EP 340 013A
(Unilever). These compositions comprise:
(a) from 17 to 35 wto of non-soap detergent-active
material consisting at least partially of anionic
surfactant, and
(b) from ~:2r8 ~.o: 45 wto of crystalline or amorphous
g1'kali ,metal aluminosi~lmcaL.e.,
the weight ratio of (b) to (a) being from 0.9:1 to 2.6:1,
preferably from 1.2:1 to 1.8:1, and optionally other
detergent ingredients to 100 wto.
CA 02034244 1999-09-13
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(2) Compositions as described in EP 351 937A (Unilever):
(a) from 12 to 70 wt~ of non-soap detergent-active
material, and
(b) at least 15 wt~ of water-soluble crystalline
inorganic salts, including sodium tripolyphosphate
and/or sodium carbonate,
the weight ration of (b) to (a) being at least 0.4:1,
preferably from 0.4:1 to 9:1 and more preferably from
0.4:1 to 5:1, .and optionally other detergent components
to 100 wt~.
These compositions preferably contain a total of
from 15 to 70 wt~ of water-soluble crystalline inorganic
salts, which may comprise, for example, sodium sulphate,
sodium ortho- or pyrophosphate, or sodium meta- or
orthosilicate. Especially preferred compositions contain
from 15 to 50 wt~, more preferably from 20 to 40 wt~, of
sodium tripolyphosphate.
As previously indicated, all these preferred classes
of detergent composition that may be prepared by the
process of the invention may contain conventional amounts
of other conventional ingredients, for example, bleaches,
enzymes, lather boosters or lather controllers as
appropriate, antiredeposition and antiincrustation
agents, perfumes, dyes and fluorescers. These may be
incorporated in the product at any suitable stage, and
the skilled detergent formulator will have no difficulty
in deciding which ingredients are suitable for admixture
in the high-speed mixer/granulator, and which are not.
- 21 - C3361
The process of the invention has the advantage over
conventional spray-drying processes that the very high
temperatures encountered in spray-drying towers are not
involved, so fewer restrictions are imposed on the way in
which heat-sensitive ingredients such as bleaches and
enzymes are incorporated into the product.
The invention is further illustrated by the
following non-limiting Examples, in which parts and
percentages are by weight unless otherwise stated.
0~0::~~~c.~~~
- 22 - C3361
EXAMPLES
Example 1
A 750 kg batch of high-bulk-density detergent powder
having the following nominal formulation was prepared
using a Fukae (Trade Mark) FS°1200 high-speed
mixer/granulator:
wt%
Linear alkylbenzene sulphonate 25.0
Nonionic surfactant 2.0
Soap 1.0
Zeolite 4A (anhydrous) ) ( 35.0
Water with zeolite ) ( 9.99
Sodium silicate 4.0
Acrylate/maleate copolymer 1.0
Fluorescer 0.18
Sodium carboxymethyl cellulose 0.9
Sodium carbonate 15.51
Total added water 2.0
Speckles 0.8
Enzyme 0.6
Perfume 0.25
100.00
The,ratio :of,zeolite (anhydrous).to totalnon-s.o;ap
surfactant in this composition was 1.'29:1.
CA 02034244 1999-09-13
- 23 -
The process was carried out as follows:
(i) Solid ingredients as specified below were dry-mixed
in the Fukae mixer for 1 minutes, using a stirrer speed
of 100 rpm and a cutter speed of 2000 rpm.
Zeolite 4A (hydrated) 40.0
Sodium carbonate 19.53*
Sodium carboxymethylcellulose 0.9
Sodium silicate 4.0
Acrylic/maleic copolymer 1.0
Fluorescer 0.18
Fatty Acid 0.92
Total solids 66.53
*This amount o:E sodium carbonate represented a 5-fold
excess over that required for neutralisation of the
alkylbenzene sulphonic acid (see paragraph (ii) below).
(ii) Linear alkylbenzene sulphonic acid (23.5 parts) was
added over a period of 2-3 minutes while the mixer was
operated at a :stirrer speed of 100 rpm and a cutter speed
of 2000 rpm. The mixer was then operated for a further 1
minute at the Name stirrer and cutter speeds. The
temperature was maintained below 60'C by means of a
cooling jacket filled with water. Throughout this step,
the reaction mixture remained in particulate form. No
water was added before or during this step.
Total liquids 23.5
Solids as ~ of total 73.9
~~~34~ ~4
- 24 - C3361
(iii) Nonionic surfactant (2.0 parts) was added over
a period of 1 minute, while the mixer was operated at a
stirrer speed of 80 rpm and a cutter speed of 2000 rpm.
Water (1.6 parts) was then added over a period of a
further 1 minute while the mixer contimied to operate at
the same stirrer and cutter speeds. The mixer was then
operated at the same stirrer and cutter speeds for a
further 18 minutes to effect granulation, while the
temperature was maintained at about 60°C by means of a
l0 cooling jacket filled with water. The product of this
step was a granular solid.
Total liquids 27.1
Solids as o of total 71.1
(iv) Zeolite (a further 5 parts) was then added as a
flow aid, while the mixer was operated for 1 minute at a
stirrer speed of 80 rpm without the cutter.
The resulting powder was free-flowing, had a bulk
density of 878 g/litre, and contained 96 wto of particles
<1700 ~,m. The particle porosity was 0.1.
Coloured speckles of the same powder (0.8 parts) and
enzyme granules (0.6 parts) were mixed with the powder
using a rolling drum, and perfume (0.25 parts) were
sprayed on, to give a fully formulated high-bulk-density
detergent powder . ha:vi;ng ~, exc,el~.ent; powder propertues.
CA 02034244 1999-09-13
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Further 750 kg batches of the nominal formulation
given in Example 1, minus the postdosed ingredients
(speckles, enzyme, perfume) were prepared using the Fukae
FS-1200 mixer.
Examples 2 to 4 were in accordance with the present
invention, without temperature control during the
neutralisation step: while Comparative Example A employed
temperature control (a water jacket containing water
cooled to 9'C) during the neutralisation step and was in
accordance with EP 352 135A (Unilever) published on 24
January 1990.
Processing was as follows:
(i) The solid ingredients were dry-mixed in the
Fukae mixer fo:r 1 minute, using the stirrer and cutter
speeds specified in Table 1 below.
(ii) Linear alkylbenzene sulphonic acid was added,
over the period shown in Table 1, below, while the mixer
was operated at the same stirrer and cutter speeds. The
acid addition times varied from 1 min 30 sec to 2 min 50
sec depending on whether a single manifold or two
manifolds were used; the acid flow rate was 60 kg/min
(single manifo:Ld) or 90 kg/min (double manifold). A short
"pulverisation" stage of 1 minute at the same stirrer and
cutter speeds i=ollowed to allow for any
temperature/reaction lag. Throughout step (ii), the
reaction mixture remained in particulate form. No water
was added before or during this step.
- 26 - C3361
(iii) Nonionic surfactant was poured onto the powder
bed over a period of 1 minute, while the mixer continued
to operate at the same stirrer and cutter speeds.
Water, if required, was then sprayed onto the powder bed
over a period of a further 2 to 3 minutes while the mixer
continued to operate at the same stirrer and cutter
speeds.
The mixer was then operated at the same stirrer and
cutter speeds to effect granulation, the endpoint being
detected by means of the amperage of the stirrer motor:
The products of this step were all granular solids.
(iv) As in Example 1, further zeolite was then added
as a flow aid, while the mixer was operated at a lower
stirrer speed without the cutter.
Total batch times were in the range of from 8 to 21
minutes.
The properties of the resulting products are shown
in Table 2 below.
CA 02034244 1999-09-13
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T~ LE 1
Examples 2 - 4 and A~ x~roces~in~ conditions
Neutralisation step
Manifolds Acid Addition Stirrer/cutter
Time speeds
(min: sec) (rpm)
2 1 2:50 80/2000
3 1 2:50 80/2000
4 2 2:00 80/2000
A 2 2:30 80/2000
Granulation st~~g
Water added Granulation Process
time time
(kg) (min: sec) (min: sec)
2 6 4:10 12:40
3 4 5:45 14:30
4 4 6:00 14:10
A 5 7:00 19:00
Stirrer/cutter speeds were as in the neutralisation
step.
~~;~~~~~
- 28 - C3361
TABLE 2
Examples 2 - 4 and A: properties of products
Yield Bulk
<1700 um density
(wt%) (g/1)
2 88 819
3 89 827
4 93 836
A 91 831
The powders of all four Examples were free-flowing
and there was no significant difference between them.
CA 02034244 1999-09-13
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Further 750 kg batches of the nominal formulation
given in Example 1, minus the postdosed ingredients
(speckles, enzyme, perfume) were prepared using the Fukae
FS-1200 mixer, using higher controlled process
temperatures in order to simulate operation at high
ambient temperatures. Two manifolds were used for acid
addition in each case. The powder temperature at the end
of the neutralisation step was measured, showing Examples
5 and 6 to be 'within the present invention and
Comparative Example B to be in accordance with EP 352
135A (Unilever).
Process details are shown in Table 3 and product
properties in 'Table 4.
EXdmDles 5, 6 and B: grocessina conditions
Acid Addition Water Powder Stirrer/cutter
Time j acket s eeds
neutr)
(min: sec) ('C) ('C) (rpm)
B 1:40 warming 46'C 106/1250
5 1:29 35°C 57°C 80/2000
6 1:40 49'C 56'C 80/2000
- 30 - C3361
Granulation step
Water added Granulation Process
time time
(kg) (min: sec) (min:sec)
B nil 4:15 8:50
5 nil 16:00 21:10
6 nil 4:00 10:5 0
TABLE 4
Examples 5, 6 and 3: -properties of products
Yield Bulk
<1700 um density
(wt%) (g/I)
B 81 777
5 79 860
6 80 797
All powders were free-flowing and did not differ
significantly from one another.
CA 02034244 1999-09-13
- 31 -
ogle 7
A high-bulk-density powder having a higher content
of anionic surfactant was prepared by the process
described above under Examples 2 to 4. The formulation
was as follows:
parts
Linear alkylbenzene sulphonate 30.0
Nonionic surfactant 2.0
Soap
1.0
Zeolite 4.A (anhydrous) 35.0
Water with zeolite g.gg
Sodium silicate 4.0
Acrylate/maleate copolymer 1.0
Fluoresce:r 0 .18
Sodium ca:rboxymethyl cellulose 0,9
Sodium carbonate 15.51
The stirrer and cutter speeds were 80 rpm and 2000
rpm respectively. The acid addition time was 1 min 40
sec, two manifolds being used. Cooling water (9'C) was
used during the' neutralisation step but the temperature
nevertheless rose to 61'C at the end of acid addition. No
water was added at the neutralisation stage. The
granulation time was 5 minutes and the total batch time
10 minutes.
The product obtained had exceptionally good powder
properties:
Bulk density 791 g/1
Yield <1700Nm 70 wt~
Fines content ( <180 ~.lm) 14 wt~
Dynamic flow rate 118 ml/s
Compressibility 8.8~ v/v
CA 02034244 1999-09-13
- 32 -
Two powders containing sodium tripolyphosphate were
prepared by the process of the invention, using the Fukae
FS-1200 mixer. The batch size in each case was 670 kg.
The formulations of the final products were as follows:
$ $
Linear alkylbenzene sulphonate 31.3 25.6
Sodium tripolyphosphate 37.2 36.9
Sodium alkaline silicate 9.0 9.0
Sodium carbonate 12.0 12.8
Zeolite 4A (anhydrous) 4.4 8.7
Fluorescer 0.2 0.2
Soodium carbox~Tmethylcellulose 1.4 1.4
Alusil 2.3 2.2
Moisture 2.2 3.3
___ ___
100.00 100.00
The process was carried out substantially as
described above' under Examples 2 to 4. In each case the
zeolite was introduced wholly as part of the initial
solids charge, and the Alusil was added as a flow aid in
the final stage' of the process. The powder temperature in
the neutralisation stage was above 55'C in both cases.
;~~~~~
- 33 - C3361
Process details and powder properties were as
follows:
8 9
Maximum powder temperature (°C) 67 56
(during neutralisation step)
Total process time (min) 7 10
Yield <1700 ~m (wto) 50 96.3
Bulk density (g/1) 727 947
The powder of Example 8 had exceptionally good flow
properties, the dynamic flow rate being 139 ml/s.
