3 ~
A FREE FLOWING ANIONIC DETE~GENT AND METHOD
OF PRODUCTION THEREOF
This invention relates to detergents, and more particularly, to
free flowing, high active anionic detergents.
High active detergents, for the purposes of the present invention,
may be defined as detergents comprising more than 1 29d active matter .
Free flowing, for the purposes of the present invention, may be
defined as sufficiently mobile as to be capable of being poured or
dispensed reproducably as a measured quantity.
It is desirable that detergent powders exemplify certain
characteristics, namely, the detergent powder should be non-dusty,
free flowing, easily handled, easily dissolved and stable under normal
storage conditions.
A large proportion of the worldwide detergent market uses high
foaming powder surfactants, most of which are based on anionic active
lS matter ingredients.
It has hitherto been common practice to produce detergents in
powder form by making up a slurry of the various ingredients in
water and subsequently spray drying the slurry to yield a powder- of
typical bulk density 0 . 2 to 0 . 5 gms/ml . This method of manufacture
is expensive because heat is required to evaporate the water which
was ini~ialiy added and yet is not required in the final product.
A further method of manufacture of detergents in powder form is
by so called 'dry neutralisation'. Dry neutralisation and associated
agglomeration is normally regarded as a three part process:
1. Dry adsorption of an alkyl aryl sulphonic acid onto the
surface of an alkaline base.
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2. Addition of water to affect the reaction of the alkali and
sulphonic acid to form an alkaline sulphonate which binds the
constituents to produce a neutralised de-tergent agglomerate and
3. Coating the outside of the agglomerate with a layer of dessicant
material such as sodium tripolyphosphate, sodium carbonate or silicate.
It has previously been assumed that: there is a reasonably well
described limitation on the amount of alkyl aryl sulphonic acid which
can be adsorpted onto the surface of various alkaline bases without
first causing over agglomeration or poor flow properties. For example
it has been claimed that the adsorptive characteristics of
tripolyphosphate or other adsorptive materials are a function of their
surface area. Therefore, sodium tripolyphosphate (STPP) in powder
form must have greater adsorptivity than in granular form. Definitive
tables of the adsorptivity of STPP and other alkalies have been published
in the past giving the adsorptivity of various powders with regard to
the uptake of alkyl aryl sulphonic acid, for example do decyl benzene
sulphonic acid (DDBSA . ) This, theoretically, limits the amount of
active matter which can be formulated into a detergent powder produced
by dry neutralisation.
The table (A) below shows commonly accepted limitations of the
adsorptlvity of various bases.
TABLE A
g DDBSA/1 OOg alkali salt
STPP Powder 32 . 5
STPP low density granular 2 . 0
STPP regular density granular 2 . l
soda ash ( powder ) 2 . 2
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soda ash (granular) 0.2
Sodium metasilicate anhydrous 0.1
Sodium metasilicate 5H20 0.1
It has previously been assumed that the addition of approximately
5 1-2 % of water was necessary to cause in situ neutralisation of sulphonic
acids with alkaline bases. The product was not thought to be stable
until this reaction had been completed. It has previously been assumed
that a dessicant should be used to coat the outside of the agglomerate
to adsorb free water, usually by hydration of the dessicant, to obtain
lO a free flowing product.
According to a first aspect of the present invention, there is
provided a method of producing a free flowing, high active, anionic
detergent comprising the step of adsorbing an anionic surfactant acid
onto a powdered or granular material to l`orm an agglomerate without
15 the addition of water in the agglomeration stage.
It has been discovered that the powdered or granular detergent
composition derived from this method suprisingly has a subs-tantially
uniform particle size and may comprise high levels of surfactant acid
successfully exceeding the maximum surfactant acid content of the
2 0 pr ior art .
According to a second aspect of the present inven-tion there is
provided a free flowing, high active, anionic powdered or granular
detergent composition comprising an anionic surfactant acid adsorped
onto a powdered or granular material, said detergent composition having
25 a particle size distribution substantially within the range from 248
microns to 1752 microns.
According to a third aspect of the present invention there is
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provided a free flowing, high active, anionic, powdered or granular
detergent composition comprising a surfactant acid adsorped onto a
powdered or granular material the surfactant acid being present in the
range from 12 to 40% by weight of the total composition and the powdered
5 or granular material being present within the range from 20 to 50% by
weight of the total composition.
In a preferred embodiment of the invention, the anionic surfactant
acid is adsorbed onto heated, dry, powdered, or granular material.
In a preferred embodiment of the invention the anionic surfactant acid
lO is adsorbed onto heated dry powdered or granular form preferably in a
fluidised bed.
In a further preferred embodiment, the agglomerate so formed is
then coated by the application of a silicate and/or alkali, preferably in
a fluidised bed. The temperature of the inital part of the fluidised bed
15 is preferably above 50C and more preferably in the range from 85 to
95C
Any suitable anionic surfactant acid may be used. Suitable examples
of such are as follows: alkyl aryl sulphonic acids, fatty acid sulphonic
acids, olefin sulphonic acids, fatty alcohol ether sulphuric acid, fatty
20 methyl ester sulphonic acid, alkane sulphonic acids. More particularly
alkyl aryl sulphonic acids containing an alkyl group with 9-20 carbon
atoms and a sulphonic acid or sulphuric acid ester group (included in
the term alkyl is the alkyl portion of the aryl groups), or fatty acid
sulphuric acids obtained by sulphating alcohols with 8-18 carbon atom
25 chains. Especially valuable are linear straight chaln alkyl benzene
sulphonic acids in which the average number of carbon atoms in the
alkyl group is from 11 to 13. The amoun-t of anionic
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surfactant acid added is preferably in the range 12% to 40%, more
preferably from 12% to 35% and even more preferably from 12% to 30% of
the final product weight for weight .
We have discovered that we can adsorb up to at least 50gm
5 DDBDA/lOOgm STPP powder when operating under the conditions of
the invention thus significantly exceeding the amounts known to have
been adsorbed in previously published work, whilst still retaining the
free flowing na-ture of the end product.
The powdered or granular material may comprise any suitable alkali,
lO or alkalies, alone, or in combination with other additional ingredients.
Examples of suitable alkalies are as follows: Sodium phosphates, for
example sodium tripolyphosphate, sodium carbonate, sodium bicarbonate,
sodium silicate or other similar alkalies including potassium or magnesium
salts. The amount of alkali is preferably in the range 1096 to 95% and
15 more preferably 60% to 95% final product weight for weight.
Additional ingredients may include the following: bleaching agents
for example Sodium Perborate, corrosion inhibitors or alkaline additives,
for example, Sodium Silicates, inert fillers, for example Sodium Sulphate,
surfactants, optical brighteners, preventors of soil redeposition, (for
20 example, sodium carboxy-methyl cellulose, ) dedusting agents and
solubilisers, such as sodium xylene sulphonate, enzymes, chelating
agents, perfumes, softening agents, defoamers, bleach activators, soap,
and non ionic active material.
Any suitable apparatus may be used, but this may have to be
25 adapted to run under the appropriate conditions so as to maintain dry
conditions during the agglomeration stage. Examples of such apparatus
13'~f3278
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are as follows:
l. Static or moving machines with dividers or blades or paddles to
mix the powders. These include twin shell blenders or V blenders,
baffled drums and ribbon or paddle blenders.
5 2. Air suspension machines which suspend the particles in air whilst
liquid is sprayed onto said particles. The particle size increases until
the particles are too heavy to be suspended at which time they fall
from the air stream.
3. Apparatus in which air is used to fluidise the particles making
lO them act in a similar manner to a liquid, for example, a fluidised bed.
Sample powdered or granular detergents derived from this method
exhibit the following characteristics:
Particle Size
no more than 3% by weight of the particles are larger than l700
15 microns
no more than l % by weigh-t of the particles are less than 250
microns
average particle size 1100 to 1300 microns
Bulk density: untapped 600-720 gm/ml
tapped: 730-830 gm/ml
moisture content: less than 4~ W/W
. . _ . . _ .
angle of repose average: 37 to 38C
with minimum 36 maximum 41
sliding angle: minimum 25 maximum 28
flowrate: 30-41 cc/sec through standard orifice.
compressibility: 7-15%
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Composition of anionic detergent granulate:
The detergent composition comprises 5 to 40g~ preferably 10 to 35%
and more preferably 12 to 30% by weight of the final composition of an
anionic surfactant acid for example Sodium alkyl ar~yl sul~hate. The
5 detergent composition comprises 20 to 50% preferably 25 to 4S% and
more preferably 30 to 40% by weight of the final composition of the
powdered or granular material such as the alkaline material sodium
tripolyphoshphate. The detergent composition may also comprise any
of the optical ingredients listed on page 5 including for example any of
lO the following: soda ash, sodium sulphate, sodium carboxy methyl
cellulose, optical bleaches, sequestering agents, sodium silicates etc.
For the purpose of the present invention:-
the angle of repose is defined as the angle from the horizontal tothe line of slope of a heap of powder, the heap having been formed
15 by directing powder through a funnel into the centre of a circular
horizontal surface. The funnel is slowly raised to allow the heap to
form immediately beneath it.
The flow rate of the powder is de~ined as the rate in cubic
centimetres per second that will flow through a 1 . 25cm diameter orifice
20 with a smooth PVC funnel e~<panding at 10 to the vertical above the
or if ice .
The angle of slide is defined as the minimum angle between -the
horizontal and an inclined surface when a powder slides by gravity en
masse down that surface, the surface being a smooth, wooden unpolished
25 medium. The powder is scattered as a layer no more than 20mm deep
on the surface. The surface is raised slowly until the sliding condition
is achieved~
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The compressibility of the powder is defined as the percentage
of initial volume lost when a sample is subjected to a compressive
load, the compressive load being provided by a 10Kg weight which is
applied to a cylinder of powder of 69mm diameter for a period of 3
5 minutes.
The invention will now be described further by the following
Examples:
EXAMPLE 1
The following mixture was prepared by dry blending and then
l0 fed at a rate of typically 1.83 kg per minute onto a horizontal fluidised
bed. No water was added. The inital part of the fluidised bed was
heated to above 80C and retained at this temperature during the
experiment .
Material ~6 W/W
15 Sodium Tripolyphosphate 44 . 8
Sodium Carbonate 23.4
Sodium Carboxy-Methyl Cellulose 2.40
Sodium Sulphate 29 . 00
Optical Brightener ~TINOPAL* CBS-X) 0.40
*TINOPAL is a Trade Mark of Ciba-Geigy.
Two liquids, as defined below, were sprayed sequentially along
the fluidising bed onto the fluidised powder.
LIQUID 1. Do Decyl Benzene Sulphonic Acid ~DDBSA) at a spray
rate of 390g/min.
25 LIQUID 2. A solution comprising
% WIW
a) Sodium Silicate ~2:1 Si02:Na20~ 40.00
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b) Pigment blue 15:1 (46% Dispersion 0.18
c ) Tetra sodium sait of ethylene
diamine tetra acetic acid 3.66
d ) Water 56 .16
The solution was applied at a spray rate of 390g/min. The
combined addition of alkyl aryl sulphonic acid and silicate solution
equated to a 30.0% w/w combined percentage liquid additions.
After processing, chemical analysis indicated the powders had
the following chemical content.
% W/W
Active Detergent 15 . 6
(calculated as Sodium Alkyl Aryl
Sulphonate - Molecular Weight 322)
Sodium Tripolyphosphate 32.4
lS (calculated as P205)
Moisture 1 . 53
The product was a dust free, free flowing granular agglomerate.
EXAMPLE 2
The foliowing powder mixtures were prepared and used as in EXAMPLE
20 1,
% WlW
Sodium Tripolyphosphate 57 . 60
Sodium Carbonate 23 . 00
Sodium Carboxy-Methyl Cellulose 2 . 40
25 Sodium Sulphate 16.60
Optical Brightener (TINOPAL* CBS-X) 0.40
*TINOPAL is a Trade Mark of Ciba-Geigy.
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The composition of the two liquids sprayed along the fluidised
bed was as in EXAMPLE 1.
LIQUID 1 was applied at a spray rate of 600g/min.
LIQUID 2 was applied at a spray rate of 390g/min
The combined addition of alkyl aryl sulphonic and silicate solultion
equated to a combined percentage liquid addition of 35.0% W/W.
After processing, chemical analysis indicated the powder had the
following chemical content.
% W.W.
10 Active Detergent 23 . 9
(calculated as Sodium Alkyl Aryl
Sulphonate - Molecular Weight 332 )
Sodium Tripolyphosphate 41.7
(calculated as P205)
Moisture 1 . 73
The powder produced was a dust free, free flowing granular
agglomerate.
The method enabled a liquid addition of 35.0% W/W to the fluid
bed which is comfortably in excess of the limit of 20% imposed by
20 known methods.
Active matter content was as high as 23.3%, which is almost
twice the maximum amount of 12% of active matter achieved by known
methods, utilising a fluid bed apparatus.
The amount of alkyl aryl sulphonic acid adsorped onto the
25 tripolyphosphate and other alkalies present was well in excess of the
previously know adsorptive figures quoted in literature as shown in
TABLE A.
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In EXAMPLE 1 the theoretical maximum for successful adsorption
of alkyl aryl sulphonic acid is calculated to be 15 . 0759 of sulphonic
acid per 100 9 of initial powder mixture. The practical result of use
of the claimed method is calculated to be 21 . 3119 of sulphonic acid
5 per 1009 of initial powder mixture which is well in excess of the
results from previously known methods.
Similarly in EXAMPLE 2 the figures for theoretical maximum and
practical results are 19.2269 and 32.3119 of alkyl aryl sulphonic acid
per l OOg of initial powder mixture.
Prior art methods of dry neutralisation in whatever apparatus
have always assumed the presence of added water and have always
restricted the ratio of the amount of alkyl aryl sulphonates -to the
amount of alkali to a limit which the invention successfully exceeds.
The present invention provides a cost efficien-t method of producing a
15 high active, non-dusty, free flowing, stable anionic detergent powder
which may be easily handled and easily stored.
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