Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
WO93/161~ PCT/US93/00736
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PROCESS FOR
MAKING DETERGENT GRANULES BY NEUTRALISATION
OF SULPHONIC ACIDS
Field of the Invention
The present invention relates to a process for dry
neutralisation of sulphonic acids and to detergent
compositions made by this process.
Backqround of the ~nvention
Granular detergents have so far been principally
prepared by spray drying. In the spray drying process the
detergent components, such as surfactants and builders, are
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mixed with as much as 35-50% water to form a slurry. The
slurry obtained is heated and spray dried which requires
high energy input and expensive equipment. An efficient
method of processing detergents without slurrying in water
and then subsequently drying would be less expensive.
Procec~~- for "dry" neutralisation (ie essentially
water free) are well-known and practiced by detergent
manufacturers in the manufacture of detergent granules of
high bulk density, in particular for the neutralisation of
acid forms of anionic surfactants.
There is a need however to produce agglomerates that
have cleaning performance comparable with conventional
spray-dried granules.
It has been discovered that the rate and the
complet~necc of the neutralisation reaction can have an
impact on the performance and rate of solubility of the
detergent granules and therefore represent an important
consideration for the commercial application of such a
process.
It has now been surprisingly found that the use of
finely ground particulate neutralising agent of a narrowly
defined particle size optimises the said neutralisation
reaction, and in so doing, realises benefits in the
performance and rate of solubility of detergent granules of
high bulk density made by such "dry" neutralisation
processes. The detergent granules made by the invention
have a bulk density greater than 650 g/l.
US Pat. No. 4 515 707, published May 7, 1985,
describes a process for dry neutralisation of a detergent
sulphuric or sulphonic acid with sodium carbonate powder in
the presence of powdered sodium tripolyphosphate in a high
W093t161~ 2 1 3 o o o 7 PCT/US93/~736
shear mixer. The resulting powder is used in the
manufacture of solid detergent bars.
Japanese Pat. No. 60 072 999 discloses a batch process
whereby a detergent sulphonic acid, sodium carbonate, water
and other optional ingredients are brought together in a
high shear mixer followed by cooling to 40~C or below and
pulverising with zeolite powder and granulating.
EP A 0 420 317, published April 3, l99l, discloses a
continuous process whereby a detergent sulphonic acid,
particulate inorganic material, water and other optional
ingredients are brought together in a high speed
mixer/densifier. Material is subse~uently treated in a
moderate speed granulator/densifier. Addition of fine
powders in the second step, or between the first and second
step, is described as beneficial for the agglomeration
process.
EP A 0 430 603, published June 5, l99l, discloses a
process for preparing high active detergent agglomerates
using a finely divided particulate filler with a high oil
absorption value as a processing aid for the agglomeration
step.
Summary of the Invention
The present invention relates to a process for making
detergent articles comprising the steps of: providing a
particulate neutralizing agent comprising 50~ by volume of
particles less than 5~m in diameter and so~ by volume of
particles less than lO ~m in diameter; mixing a
stoichiometric excess of said particulate neutralizing agent
in a high shear mixer with an anionic surfactant in its acid
form so as to neutralize said anionic surfactant; and
forming said detergent particles.
The present invention also encompasses free-flowing
detergent compositions made with the process.
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Detailed Description of the Invention
A stream of dry powder ingredients is fed into a high
shear mixer where it is mixed with a liquid or paste stream
of anionic surfactant acid and, optionally, other liquid
binders. The powder stream comprises a particulate
neutralising agent, typically an alkali inorganic salt, and
neutralisation starts in the high shear mixer and continues
during subsequent processing. It is a characteristic of the
invention that the particulate neutralising agent in the
powder stream is in the form of a finely ground powder.
THE ~O~IV~':K STREAM
The powder stream contains a particulate neutralising
agent. Preferred neutralising agents include any of the
salts of carbonate or bicarbonate or mixtures thereof.
Especially suitable is calcium or sodium carbonate. The
neutralising agent should be present in a stoichiometric
c5 over the anionic surfactant acid. Preferably at
least five times as much neutralising agent should be
present than is reguired for stoichiometric neutralisation.
The powder stream may also contain any other suitable
detergent powders. Preferred powders are those which are
active in the detergency process. This includes zeolites,
sodium tripolyphosphate, silica, silicates, polymers
including copolymers of maleic and acrylic acid,
carboxymethyl cellulose, optical brighteners, ethylene
diamine tetra acetic acid and inorganic salts such as
sulphates. Other suitable ingredients, including additional
surfactants, that may be handled as solids are described
later.
It has been found that use of a finely ground
particulate neutralising agent improves the cleaning
.
WO93/161~ 2 1 ~ ~ ~ 9 ~ PCT/US93/00736
performance, solubility characteristics and cake strength
of the final detergent composition. The average particle
size of the neutralising agent should be less than 5~m. The
definitions for average particle size are given below.
It is believed that the high specific surface area of
the particulate neutralising agent improves the efficiency
of the neutralisation reaction. A narrow range of particle
size distribution is preferred, as well as a small average
particle size. Preferably 90% of the particles by volume
have an equivalent particle size of less than lO~m.
MEAN PARTICLE SIZE
The definitions of the terms particle size and average
particle size as used herein are given below:
The particle size of any given particle is taken to be
the diameter of a spherical particle occupying the same
volume as the given particle.
The average (or median) particle size is taken to be
the particle size which has 50% of the particles by volume
smaller than that particle size.
All of the data for particle sizes of the particulate
neutralising agent used herein have been measured on a
Malvern series 2600 optical laser.
Any type of mill suitable for grinding the particulate
neutralising agent to the desired particle size may be
used. A pan-cake jet mill provided by Trade Microniser,
Kent, England and an air classifier mill, supplied by
Hosokawa Micron have been found to be particularly
suitable.
WO93/161~ PCT/US93/00736
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THE ANIONIC SURFACTANT
Useful anionic surfactant acids include organic
sulphuric reaction products having in their molecular
structure an alkyl group containing from about 9 to about
20 carbon atoms and a sulphonic acid. Examples of this
group of synthetic surfactants are the alkyl benzene
sulphonic acids in which the alkyl group contains from
about 9 to about 15 carbon atoms in straight or branched
chain configuration.
Especially suitable anionic surfactant acids are linear
alkyl benzene sulphonates in which the alkyl group contains
from about ll to about 13 carbon atoms.
Other useful surfactant acids include alpha sulphonated
fatty acid methyl esters, olefin sulphonates and beta
alkyloxy alkane sulphonates.
Mixtures of the above may also be used.
OTHER LIQUID BINDERS
Other liquids may be sprayed into the high shear mixer
including amino polyphosphates, diethylene triamine penta
acetic acid and additional anionic surfactants (as
neutralised salts), nonionic, cationic, ampholytic and
zwitterionic surfactants.
Especially suitable amino polyphosphonates include
diethylene triamine penta methylene phosphonic acid and
ethylene diamine tetra methylene phosphonic acid.
Especially suitable additional anionic surfactants are
water-soluble salts of the higher fatty acids. This
includes 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 alkylammonium salts
of higher fatty acids containing from about 8 to about 24
carbon atoms, and preferably from about 12 to about 18
WO93/161~ PCT/US93/00736
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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 the mixtures of fatty acids derived from coconut
oil and tallow, i.e., sodium or potassium tallow and
coconut soap.
Useful anionic surfactants also 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 l0 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
obt~in~ by sulfating the higher alcohols (C8-Cl8 carbon
atoms) such as those produced by reducing the glycerides of
tallow or coconut oil
Other anionic surfactants herein are the sodium or
potassium salts of alkyl phenol ethylene oxide ether
sulfates containing from about l to about l0 units 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 from about l to about l0 units of ethylene oxide
per molecule and wherein the alkyl group contains from
about l0 to about 20 carbon atoms.
Water-soluble nonionic surfactants are also useful as
secondary surfactant in the compositions of the invention.
A particularly preferred paste comprises a blend of
nonionic and anionic surfactants having a ratio of from
about 0.0l:l to about l:l, more preferably about 0.05:1.
Nonionics can be used up to an equal amount of the primary
organic surfactant. Such nonionic materials include
compounds produced by the condensation of alkylene oxide
WO93/16154 PCT/US93/00736
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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 16 carbon atoms, in either a straight chain
or br~nc~P~ chain configuration, with from about 4 to 25
moles of ethylene oxide per mole of alkyl phenol.
Preferred nonionics are the water-soluble condensation
products of aliphatic alcohols containing from 8 to 22
carbon atoms, in either straig~t chain or branched
configuration, with from 4 to 25 moles of ethylene oxide
per more of alcohol. Particularly preferred are the
con~e~tion products of alcohols having an alkyl group
containing from about 9 to 15 carbon atoms with from about
4 to 25 moles of ethylene oxide per mole of alcohol; and
condensation products of propylene glycol with ethylene
oxide.
Semi-polar nonionic surfactants include water-soluble
amine oxides containing one alkyl moiety of from about 10
to 18 carbon atoms and 2 moieties selected from the group
consisting of alkyl groups and hydroxyalkyl groups
cont~ining from 1 to about 3 carbon atoms; water-soluble
phosphine oxides containing one alkyl moiety of about 10 to
18 carbon atoms and 2 moieties selected from the group
consisting of alkyl groups and hydroxyalkyl groups
containing from about 1 to 3 carbon atoms; and water-
soluble sulfoxides containing one alkyl moiety of from
about lo to 18 carbon atoms and a moiety selected from the
WO93/161~ PCT/US93/~736
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group consisting of alkyl and hydroxyalkyl moieties of from
about 1 to 3 carbon atoms.
Ampholytic surfactants include derivatives of
aliphatic or aliphatic derivatives of heterocyclic
secondary and tertiary amines in which the aliphatic moiety
can be either straight or branched chain 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.
Useful cationic surfactants include water-soluble
quaternary ammonium compounds of the form R4R5R6R7N+X-,
wherein R4 is alkyl having from 10 to 20, preferably from
12-18 carbon atoms, and R5, R6 and R7 are each Cl to C7
alkyl preferably methyl; X~ is an anion, e.g. chloride.
Examples of such trimethyl ammonium compounds include C12_
14 alkyl trimethyl ammonium chloride and cocalkyl trimethyl
ammonium methosulfate.
Note that some of these components may be handled in
solid form in which case they should be considered as part
of the powder stream rather than liquid binders.
RATIO OF ANIONIC SURFACTANT/BINDERS TO POWDER STREAM
The ratio of liquid ingredients (anionic surfactant
acids and binders) to powder ingredients is limited by the
stickiness of the powder produced. A ratio from 1:1 to 1:4
is preferred. Most preferred is from 1:2 to 1:3.
HIGH SHEAR MIXER
WO93/161~ ~1 3 o o ~ 7 PCT/US93/00736
A preferred high shear mixer is the Loedige R CB
series manufactured by Loedige Maschinenbau GmbH,
Paderhorn, Germany. Operated at speed range from 500 to
2000 rpm and preferably cooled to maintain the temperature
below 40~C.
The residence time is from 5 to 30 seconds, preferably
about l0 seconds. The resulting granules should be further
processed to give finished agglomerates as described below.
Other suitable high shear mixers are believed to be Zig-Zag
Blenders manufactured by P K Niro, Denmark.
Also suitable are the Eirich R batch mixers manufactured by
Gustau Eirich, Hardheim, Germany. In this ty~pe of batch
mixer the agglomerates may be formed directly with a mixing
time of about l minute without the need for further
processing.
The powder stream may be fed to the high shear mixer
by any suitable powder handling and conveying system.
The anionic surfactant acid and any other liquid
binders will normally be pumped into the high shear mixers
through conventional nozzles including spray nozzles.
FURTHER PROCESSING OF THE DETERGENT GRANULES
The granules made by the process described hereinabove
are suitable for further processing into detergent
agglomerates. This further processing includes the
continuing neutralisation of the anionic surfactant acid by
the particulate neutralising agent. This may be achieved by
further mixing in a moderate speed granulator. Suitable
mixers include the Loedige R KM mixers. The detergent
agglomerates made by the process comprise anionic surfactant
salt, coming from the neutralisation of the acid form of the
anionic surfactant and particulate neutralising agent, in an
amount of less than 40~, preferably 28~ by weight of the
agglomerate.
Residence time is from l to l0 minutes, preferably
about 5 minutes, with cooling if necessary.
'B
WO93/161~ ~1 3 ~ J7 PCT/US93/~736
Additional liquid or powder streams may optionally be
added to the moderate speed granulator, or between the two
mixers. Any suitable detergent ingredient may be used,
including any of those previously described above.
The resulting particles may then be dried in one or
more cooling or drying steps. Suitable equipment includes
commercially available fluid bed driers and air lifts.
-FINES RECYCLING
Fine particles (less than about lSO ~m) may be removed
from the final powder stream and may be recycled into the
~ocess via the high shear mixer. Any commercially
available air separation equipment, in combination, if
n~C~ccAry with suitable filters may be used. Suitable
te~hniques will be familiar to the man skilled in the art.
If fines removal and recycling is effectively carried out,
then there will be little or no finely ~oul.d particulate
l.euLlalising agent detectable in the finished composition.
However if the fines removal and recycling operation are
not carried out, or are not carried out effectively, then
there may some finely ground particulate neutralising agent
present in the finished composition.
The resulting agglomerates should have a bulk density
greater than 650 g/l and should be crisp particles of low
porosity.
FINISHED DETERGENT COMPOSITION
The agglomerates may be mixed with other powder
ingredients to give a free-flowing granular detergent
composition. Alternatively the agglomerates themselves may
be used as the finished composition. A detergent
composition made according to the present invention should
WO93/161~ PCT/US93/00736
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comprise from 50~ to 100% by weight of the agglomerates,
preferably from 80% to 100%.
Other detergent ingredients may be sprayed on to the
granular detergent, for example, nonionic surfactants,
perfumes, or added as dry powders to the agglomerates, for
example, bleach and bleach activators, enzymes, polymers
including polyethylene glycol
EXAMPLE
The detergent agglomerate was prepared by dry
neutralization of Cll-Cl3 linear alkyl benzene sulphonate
with sodium carbonate. The sodium carbonate (light soda
- ash ex ICI) was prepared to 5 different particle sizes as
defined in samples A to E.
A) Carbonate ground in a pancake jet mill (ex Trade
Micronizing)
B) Carbonate ground in an air classifier mill (ex Hosokawa
Micron)
C) Carbonate ground in a pin mill (ex Alpine)
D) Carbonate ~ound in a hammer mill (ex Alpine)
E) Carbonate commercially supplied by ICI (Light soda ash)
a B C D E
CARE~ONATE PARTICLE SIZE (um)~
MEDIAN (c~%) 3.4 5.7 18.3 59.6 73.2
<~% 4.2 15.3 69.l 152.8 209
SrtCI~lC SURFACE AREA (m~/cc) 1 . 68 1.3l 0.98 0.25 0.25
1. Carbonate particle size is measured in a MALVERN series
2600 laser particle sizer. The median indicates that
50% by volume of the particles measured are smaller
than the particle size given in that row of the table.
<90~ indicates that 90% by volume of the particles
WO93/161~ 2 13 0 ~ a ~ PCT/US93/00736
measured are smaller than the particle size given in
that row of the table.
The following ingredients were mixed in an Eirich
(batch) mixer. The powder ingredients were charged to the
mixer first. The liquid ingredients were added last and
the resultant agglomerate was formed during a mixing period
of l minute.
LIO~ID8
LINEAR ALKYL BENZENE SULPHONIC ACID23%
PHOSPHONIC ACID 2%
POWDER8
CARBONATE 21%
ZEOLITE 4-6%
PENTA SODIUM TRIPOLYPHOSPHATE 40%
SODIUM SILICATE 6%
MISr~TT~EOUS (POLYMERS etc.) to balance
The resultant agglomerates coming out of the Eirich,
were then prepared for physical properties testing and
subsequently made into finished product for performance
testing as outlined below.
_ B _ D E
R~ ,~R~.~ 8TAIN REMOVAL 0 -0.8 -0.6 -0.7 -l.0
~P8~)l
~GG~nMFP~TE CA~E 8TR~_,n2 0 2.5 6.4 l0.5 9.4
~OLUBILITY GRADE3 3 1 2 2 0
D~N8ITY la/l) 850822 602 600 664
AGÇ~O~P~TE MEAN PARTICLE 370 336 333 337 347
8IZE (um)4
W093/161~ PCT/US93/00736
l. The bleachable stain removal is measured as follows:
finished product is prepared by mixing 85% by weight of
agglomerates with 15% by weight of sodium perborate
mixed with a bleach activator. We use a NATIONAL semi
automatic Lab J28 twin tub Japanese washing machine.
The f;nish~ product (70 g) is poured in 30L of water
(water hardness is 2.0 mmol Ca2+/L, water temperature
is 30~C) containing l to 2 kg of preferably soiled load
and a set of bleachable stains (coffee, tea, black
grapes, etc...). The overall bleachable stain removal
profile of the agglomerate finish product is compared
to that of an identical formula prepared by a
conventional spray-drying process. The scale goes from
-4 to +4 Panel Score Units (PSU), the product scores O
if it has the same stain removal profile as the
reference, a negative number on the PSU scale indicates
that the test product performs worse than the
reference.
2. The agglomerate cake strength is measured as follows:
we put lOOg of agglomerate in a test pot and we subject
the sample to a lO kg load for 2 min. The resulting
cake formed is then broken by a traversing needle. The
force n~e~e~ to break the cake is recorded on a scale
from O to ll pounds. We target for a product which
scores between O (the cake breaks easily) to 3 (upper
limit for acceptable cake strength).
3. Solubility grades are measured as follows: we pour 90 g
of finish product (prepared in the same way as in
section 2.) in an acrylic pouch (20x40cm). The pouch
is closed by sewing it, and is put in the same type of
washing machine as in section 2 in 3OL of water at 30 C
containing l.5 kg of clean load. After lO minutes of
gentle agitation the pouch is opened and graded with
regard to undissolved detergent products remaining on
the fabric, on a scale from O (bad) to 4 (excellent).
WO93/161~ 2 1 ~ ~ Q ~ ~' PCT/US93/00736
We have set a solubility grade target of 3 and above
based on the evaluation of granular detergents
currently on the market.
4. Agglomerate mean particle size is measured on a
st~n~Ard Tyler sieve. The corresponding weight
fractions were converted to a log normal distribution,
from which average particle size is recorded.
-It can be seen that the agglomerates and fin;che~
compositions made according to the invention from sample A
(the most finely ~ou"d carbonate) give significant
benefits in cleAning performance and physical
characteristics, when compared to the agglomerates and
finish~ compositions made from samples B-E (carbonates
with particle size outside of the pL.--ent claimed range).
The above results also show that the fini Ch~ detergent
composition made according to the present invention from
sample A show a cleaning performance comparable to an
identical composition made by a conventional spray-dry
process.
