Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CLEANING COMPOSITIONS
This invention relates to cleaning compositions and, in particular,
particulate cleaning
compositions to be formed into moulded bodies for use in, for example, fabric
washing,
dishware washing, stain removal and water softening.
Detergent compositions in the form of tablets are widely described and are
currently
enjoying increasing popularity with consumers. They are described, for
example, in
GB 0 911 204 (Unilever), US 3 953 350 (Kao), DE 19 637 606 (Henkel), EP 0 711
827
(Unilever) and WO 98/40463 (Henkel). Tablets for machine dishwashing
applications are
described in, for example, WO 96/28530 (P&G). Tabletted detergents and
cleaning
compositions have several advantages over powdered or liquid compositions:
they are easier to
dispense and handle, do not require measuring to obtain the correct dose and,
being compact,
are more economical to store and transport.
Tablets of cleaning compositions are generally made by compression or
compaction
of a quantity of the composition in the form of particles. Production of
tablets which are
sufficiently hard and strong to withstand storage and handling requires a
relatively high pressure
to be used in this compaction process. It is then necessary that, despite this
compaction, the
tablets are able to disperse and dissolve rapidly when added to wash water.
One approach to achieving good dispersion of the tablet is to include in the
tablet a
particulate insoluble but water-swellable agent. These particles then swell
with ingress of water,
leading to stresses in the tablet and thence to break-up of the tablet. Thus
WO 98/55583
(Unilever) describes the use of 'water-insoluble, water-swellable polymeric
material' which
'promotes disintegration of the tablets in water'. Typical swelling agents
which have been
disclosed as possible tablet disintegrating agents are starches, cellulose and
cellulose
derivatives, alginates, dextrans, cross-linked polyvinyl pyrrolidones,
gelatines and formaldehyde
casein as well as a wide variety of clay minerals and certain ion-exchange
resins.
These water swelling agents have no function in fabric washing except to aid
tablet
disintegration. Furthermore, because they are insoluble and of relatively
large particle size, they
tend to deposit on clothes during the wash (see, for example, WO 98/55575
(Henkel) and WO
98/55582). As a result, several attempts have been made to minimise the
deposition of these
disintegrants, for example by combining such a water-swellable, insoluble
disintegrant with a
second, highly soluble disintegrating aid - see WO 98/55582 (Unilever). Other
attempts have
included use of a preferred particle size of the disintegrant. Thus, for
example, WO 98/55583
(Unilever) claims use of such material at a particle dimension of at least 400
tam to give more
efficient disintegration. On the other hand, WO 98/55575 (Henkel) teaches the
use of cellulose
disintegrating aids with a particle size of less than 100 Vim, in order to
minimise deposition. This
material is co-granulated with 'microcrystalline cellulose and/or one or
several ingredients of
detergents and cleaning agents'.
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Surprisingly, we have now found that if a water-swellable disintegrating aid
is co
granulated with an insoluble or sparingly soluble, hydrophilic solid before
being incorporated
into a tablet, then the disintegrant is much more efficient in disintegrating
the tablet in use. Thus,
less of the disintegrating aid needs to be added for effective disintegration,
lowering the
probability of deposition of the disintegrating aid on the substrate being
cleaned.
The present invention seeks to provide a particulate cleaning composition in
the form
of a moulded body and which is relatively inexpensive to manufacture and
sufficiently robust to
withstand handling during production and packaging processes but readily
breaks up and
dissolves when contacted with an aqueous medium during the cleaning process
for which it is
intended without resulting in undue deposition on the substrate being cleaned.
According to the present invention there is provided a cleaning composition,
the
composition including disintegrant in the form of granules comprising a water
insoluble inorganic
material and a water-swellable agent which, in its anhydrous state, comprises
no more than
20% of the combined weight of said inorganic material and said agent of the
granular
disintegrant, the granules being combined with the active ingredients of the
cleaning
composition in a compacted moulded body.
According to a particular aspect of the invention, a granular composition
suitable for
use in a cleaning composition consists essentially of a water insoluble
inorganic material and a
water-swellable agent which, in its anhydrous state, comprises no more than
20% of the
combined weight of said inorganic material and said agent of the granular
composition.
By "water insoluble", we mean a compound with a water solubility of less than
5
grams, preferably less than 1 gram, per 100 grams water (at a temperature of
25°C).
Preferably, the water-swellable agent comprises, in its anhydrous state, no
more than
15%, more preferably no more than 10%, of the combined weight of said
inorganic material and
said agent of the granular disintegrant. In a typical composition of the
invention, the water
swellable agent comprises, in its anhydrous state, no more than 8%, e.g. 7.5%
or less, of the
combined weight of said inorganic material and said agent. Generally, at least
1 % of the
combined weight of the water-swellable agent and the inorganic material in the
granules
comprises water-swellable agent.
A feature of the invention is the relatively small amount of water-swellable
agent that
may be employed while securing satisfactory properties for the compacted
cleaning
composition. Frequently, the amount of water-swellable agent in the cleaning
composition is
less than 2% by weight. Preferably, the amount is less than 1 % of the
cleaning composition but,
usually, at least 0.2% of the water-swellable agent is present in the cleaning
composition.
In one embodiment of the invention the inorganic material used in the
formation of
the disintegrant granules comprises a silica.
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In a second embodiment of the invention the inorganic material used in the
formation
of the disintegrant granules conveniently comprises a material which acts as a
functional
ingredient of the cleaning composition. In this instance, the inorganic
material may be an
aluminosilicate such as zeolite P, A or X or mixtures thereof, with zeolite P
being preferred.
Alkali metal aluminosilicates, especially zeolites, are commonly used in
detergent
compositions as a detergency builder. Where a cleaning composition of the
invention is one
containing an alkali metal aluminosilicate as detergency builder, preferably
at least part of the
aluminosilicate constituent of the cleaning composition is employed as the
inorganic material
used in the formation of the disintegrant granules. For instance, the
aluminosilicate constituent
typically comprises about 10 to about 60% by weight of the cleaning
composition and
preferably, when zeolite is used in the disintegrant granules and as a
detergency builder, then
at least 1 % of the detergent composition comprises a zeolite constituent
employed in the form
of disintegrant granules.
The water-swellable agent preferably has an average primary particle size up
to
about 600 Vim, but, conveniently, has an average primary particle size of no
more than 200 pm,
preferably no more than 100 Vim, and a water swelling capacity of at least 5
ml/gram, preferably
10 ml/gram and more preferably 20 ml/gram as determined in the test described
hereinafter.
Typically the water-swellable agent comprises polymer, frequently a wholly or
partially cross-linked polymer, e.g. natural cellulose, cross-linked
cellulose, (sodium) carboxy
methyl cellulose, cross-linked sodium carboxymethyl cellulose, pre-gelatinised
starch, cross
linked starch, or cross linked polyvinyl pyrrolidone. Currently preferred are
Aquasorb A500 (ex
Hercules) and Ac-Di-Sol (ex FMC Corp).
The moulded body formed using the cleaning composition of the present
invention
may consist wholly of the cleaning composition or alternatively the moulded
body may comprise
a number of discrete portions, at least one of which comprises a cleaning
composition in
accordance with the invention. In this event, the remaining portion or
portions of the moulded
body may be constituted by at least one other ingredient, usually one suitable
for use in
detergent and cleaning applications such as fabric washing, dishware washing,
stain removal
and water softening.
Cleaning compositions of the invention may also contain, as essential
ingredients,
one or more detergency builders (wholly or partly incorporated in the
disintegrant granules),
and/or one or more detergent-active compounds which may be chosen from soap
and non-soap
anionic, cationic, nonionic, amphoteric and zwitterionic detergent-active
compounds, and
mixtures thereof and/or other conventional additives.
A further aspect of the invention comprises a process for the preparation of a
cleaning composition comprising forming a granular disintegrant composition
consisting
essentially of a water insoluble inorganic material and a water-swellable
agent which, in its
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anhydrous state, comprises no more than 20% of the combined weight of said
inorganic
material and said agent of the granular composition and mixing said granular
composition with
one or more detergent-active compounds and, optionally, with one or more
detergency builders.
Alkali metal aluminosilicates are favoured as environmentally acceptable water
s insoluble builders, e.g. zeolites A, X and P or mixtures thereof. Other
inorganic detergency
builders include layered sodium silicate as described in US-A-4 664 839 and
marketed by
Hoechst as SKS-6, and alkali metal (generally sodium) carbonate. Water-soluble
phosphorous
containing detergency building compounds such as alkali metal orthophosphates,
metaphosphates, pyrophosphates and polyphosphates may be used. Also possible
are organic
detergency builders such as polycarboxylate polymers, e.g. polyacrylates,
acrylic/maleic
polymers, and acrylic phosphonates, monomeric polycarboxylates, e.g.,
gluconates,
oxydisuccinates, glycerol mono- di- and trisuccinates,
carboxymethyloxysuccinates, carboxy-
methyloxymalonates, dipicolinates and hydroxyethyliminodiacetates.
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.
The preferred detergent-active compounds that can be used are soaps and
synthetic
non-soap anionic and nonionic compounds. Anionic surfactants are well known to
those skilled
in the art. Examples include alkylbenzene sulphonates, particularly sodium
linear alkylbenzene
sulphonates having an alkyl chain length of Ce - C,S; primary and secondary
alkyl sulphates,
particularly sodium Ce - C,5 primary alcohol sulphates; olefin sulphonates;
alkane sulphonates;
dialkyl sulphosuccinates; and fatty acid ester sulphonates.
Nonionic surfactants that may be used include the primary and secondary
alcohol
ethoxylates, and ethoxylates of esterified fatty acids, especially the C9 -
C,5 primary and
secondary alcohols ethoxylated with an average of from 3 to 20 moles of
ethylene oxide per
mole of alcohol.
The choice of surfactant, and the amount present, will depend on the intended
use of
the detergent composition. For example, for machine dishwashing a relatively
low level of a low-
foaming nonionic surfactant is generally preferred. In fabric washing
compositions, different
surfactant systems may be chosen, as is well known by the skilled detergent
formulator, for
handwashing products and for machine washing products.
The total amount of surfactant present will of course depend on the intended
end use
and may be as low as 0.5% by weight of the total composition, for example, in
a machine
dishwashing composition, or as high as 60% by weight of the total composition,
for example, in
a composition for washing fabrics by hand. For fabric washing compositions in
general, an
amount of from 5 to 40% by weight of the total composition is generally
appropriate.
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Generally, cleaning compositions of the invention will contain from 1 to 20%
by
weight of the disintegrant granules based on total weight of the composition.
Frequently the
cleaning compositions will contain from 4 to 10 % by weight of the
disintegrant granules.
A suitable type of cleaning composition suitable for use in most automatic
fabric
washing machines contains both anionic and nonionic surfactants. Cleaning
compositions
according to the invention may also suitably contain a bleach system. Machine
dishwashing
compositions may suitably contain a chlorine bleach, while fabric washing
compositions may
contain peroxy bleach compounds, for example, inorganic persalts or organic
peroxyacids,
which may be employed in conjunction with activators to improve bleaching
action at low wash
temperatures. Again, the skilled detergent worker will have no difficulty in
applying the normal
principles to choose a suitable bleach system.
Other materials that may be present in detergent compositions of the invention
include sodium silicate, fluorescers, antiredeposition agents, inorganic salts
such as sodium
sulphate, enzymes, lather control agents or lather boosters as appropriate,
pigments, and
perfumes. This list is not intended to be exhaustive.
Procedures and Tests
Granule Production
The granules of inorganic material and swelling agent may be prepared by any
of the
methods that will be known to those skilled in the art, e.g. by blending the
dry ingredients in a
mixer (such as a Pek mixer available from George Tweedy & Co of Preston - 281b
S.A.
Machine) and compacting on a roller compactor (Alexanderwerk WP50 -
manufactured by
Alexanderwerk AG, D 5630 Remscheid 1, Germany). A typical preparative method
is now
described in detail with reference to silica as the inorganic material. Silica
and water swelling
organic particulate are blended together, in the appropriate proportions, in a
Pek mixer for 30
minutes. A minimum of 2 kg of blended material so prepared is compacted by
feeding into an
Alexanderwerk roller compactor, fitted with a sintered block vacuum deaeration
system. The
roller pressure setting is selected according to the strength of granule
desired, higher pressures
leading to stronger granules. Generally, roller pressure is between 8 and 25
MPa and a typical
roller pressure is 10 MPa. The compacted material from the compactor is fed
into a granulator,
which forms part of the machine, and forced through a mesh and the resulting
granules are then
screened to the desired particle size range, e.g. an average particle size of
250 to 1500 ym,
using standard laboratory sieves. Preferably, the particles have a size range
of 500 to 1200 Vim.
Tablet Production
Tablets used in the Examples that follow were produced using a 45 mm diameter
die
set (stainless steel) in conjunction with a Universal Testing Machine Type No.
2030 from Zwick
GmbH, Ulm, Germany. A known quantity, 40-45 grams, of the cleaning composition
which
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comprised the compositions mentioned in the Examples below was placed in the
die, the die
plunger was inserted and the assembly was placed between the platens of the
Zwick machine
which was operated to apply a predetermined pressure to produce a tablet
having a defined
density and, in particular, a dimensionally stable and fracture resistant
tablet. Tablets thus
produced were cylindrical in shape, with a diameter of 45 mm and a height of
about 20 mm.
Tablets with different densities were produced in order to determine the
tablet disintegration and
conductivity profiles. Tablets prepared had densities in the range 1250-1450
kg/m3, which are
typical values for commercial fabric washing tablets found in the Western
European market in
1998-9.
Determination of tablet disintegration profile
Method 1 (Dynamic)
The tablet disintegration profile provides an indication of the extent to
which various
tablets (e.g. different compositions, different densities) disintegrate under
the defined
conditions.
4500 g of demineralised water at 20°C were added to a 5 litre vessel
fitted with pH,
conductivity and temperature probes and maintained at a constant temperature
of 20°C by
immersion in a water bath. The tablets to be tested were inserted into a metal
cage having the
dimensions 9 cm x 4.7 cm x 2.7 cm and having 16 apertures (each about 2 mm
square) per
cm2. The metal cage was attached to the shaft of an overhead stirrer
(Heidolph/Janke and
Kunkel stirrer) to allow it and its contents to be rotated while immersed in
the demineralised
water. Prior to testing, the empty cage was immersed in the demineralised
water and rotated at
80 rpm for a short period of time until the temperature of the demineralised
water as detected by
the temperature probe had stabilised at 20 ~ 0.2°C. At this time, the
conductivity, pH and
temperature values registered by the respective probes were recorded. The
stirrer was then
switched oft to allow the cage to be raised out of the water so that a pre-
weighed detergent
tablet to be investigated could be inserted into the cage. The cage was then
re-immersed in the
demineralised water together with the inserted tablet and the stirrer was
switched on to resume
rotation of the container at 80 rpm. Measurements of conductivity and pH,
initially at 15 second
intervals for one minute and thereafter at one minute intervals, were made
over a period of 10
minutes after which time the cage was raised out of the demineralised water to
allow the
residue of the tablet to be removed. The residue was then dried in an oven at
105°C so that the
dry weight of the residue could be calculated as a percentage of the original
tablet weight. This
procedure was repeated for a number of tablets having different compositions
and different
densities.
Method 2 (Static)
45008 of tap water at 20° C were added to a 5 litre vessel, which was
maintained at
20° C by immersion in a water bath. The tablets to be tested were
weighed and inserted into a
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metal cage 20 cm in diameter with 1 cm2 perforations. The cage was lowered
into the 5 litre
vessel and left for 60 seconds. The cage was then removed from the water,
residue of the
tablets was placed on an aluminium tray, dried for 24 hrs at 105° C and
weighed to determine
the percentage which had not disintegrated.
Determination of Tablet Conductivity Profile
The tablet conductivity profile provides an indication of the extent to which
various
tablets (e.g. different compositions, different densities) dissolve under the
defined conditions.
Conductivity measurements were obtained from the conductivity probe mentioned
in Method 1
above at the same time as the tablet disintegration was measured.
Measurements of conductivity and pH were taken, initially at 30 second
intervals for
ten minutes and thereafter at one minute intervals for a further 20 minutes or
until the
conductivity measurements were observed to have reached a plateau
corresponding to
substantially total dissolution of the soluble portion of the tablet, i.e.
equilibration of the tablet
with water. This procedure was repeated for a number of tablets having
different compositions
and different densities.
Determination of water swelling capacity of water-swellable agent
To demonstrate the water swelling capacity of the water-swellable agent, 19.6
g of the
agent was blended with 0.4 g of ultramarine pigment and compressed into a
tablet using a
laboratory tablet press at about 250 Mpa to give a tablet 32 mm in diameter.
This was crushed
and sieved to give granules 500-1000 Nm in size. A glass tube, 33 mm in
internal diameter and
about 30 cm long with a sintered porous glass disc (porosity 1 ) fitted at one
end was immersed
upright, with said one end lowermost, in a large beaker of water (at
25° C) so that the water
level rose to about 14 cm above the sintered glass. 1 g of granules was added
to the tube and
allowed to settle onto the sintered glass disc. With this arrangement water
has access to the
granules from both above and below. The granules immediately began to swell,
forming a jelly-
like mass. The ultramarine pigment imparted a blue colour to the mass making
it easy to see
the top and to record its height. The height of the swelling mass was recorded
at intervals and
showed an initial rapid rise followed by a levelling off after about 20-30
minutes. From the
diameter of the tube, the volume of the swollen mass can be calculated. The
result was
expressed as ml/g water-swellable agent after 20 minutes.
EXAMPLE 1
Conductivity and disintegration profiles were investigated for a number of
tablet
formulations and densities, all based on concentrated Persil (Registered Trade
Mark) original
non-Biological detergent powder as manufactured by Lever Brothers of Kingston-
upon
Thames, UK - formulation as sold in the UK. The detergent powder was blended
with different
amounts of disintegrant granules. In each instance, the disintegrant granules
comprised a water
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insoluble inorganic material, specifically a zeolite or a silica or a
combination thereof, and a
water-swellable agent. For comparative purposes, granules consisting of Persil
powder alone or
comprising a water-swellable agent or a mixture of a water soluble material,
specifically sodium
silicate or sodium carbonate, and a water-swellable material were also
prepared and tested. In
the Examples given below, Doucil A24 (Trade Mark) is a P-type zeolite sold by
Crosfield Limited
of Warrington, UK; SD2255 is a silica also obtainable from Crosfield Limited;
Doucil 4A (Trade
Mark) is a 4A zeolite obtainable from Crosfield Limited; the sodium disilicate
is obtainable from
Crosfield Limited under the trade mark Pyramid 95; the sodium carbonate is
obtainable from
Solvay Chemicals Limited (identified in their product literature as Soda Ash
(Sodium Carbonate)
Light Rheinberg); and the water-swellable agent was sodium
carboxymethylcellulose as sold
under the trade mark Aquasorb A500 by Hercules Limited of Salford, UK.
TABLE 1
Sodium
Property SD2255 Doucil Doucil DisilicateSoda Aquasorb
A24 4A Ash
Surface 650 NM NM NM NM NM
Area
(m2/9)
Pore Volume1.3 NM NM NM NM NM
(ml/g)
APS (pm) 5 1.2* 3* 100* See 40*
below
Moisture 2 10* 20* 18-20* < 1.5 5*
Content
(%
by weight)
Oil absorption228 60* 40* NM NM NM
(g/100g)
NM = Not measured
In Table 1, APS represents average particle size (dso) as measured using a
Malvern
Mastersizer (Trade Mark) obtainable from Malvern Instruments in the UK and the
values marked
* are taken from typical data for the product or from specifications supplied
by the manufacturer.
The Soda Ash used in the Examples had a bulk density of 0.53 kg/dm3 and was
found to have a
particle size distribution (by sieve analysis) as follows:
>1000ym=1wt%
500 - 1000 ~m = 0.5 wt
250-500~m=3.5wt%
75 - 250 pm = 74.5wt
0-75~m=20.5wt%
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The different formulations of the disintegrant granules (on a by weight basis)
are
given in Table 2.
TABLE 2
Granule Code Wt. % of AquasorbRemainder of Granule
A500 in granule (Wt.
and Material)
A 10 90% SD2255 Silica
B 10 45% SD2255 Silica,
45% Doucil A24
C 10 90% Doucil 4A
D 10 90% Doucil A24
E 7.5 92.5% Doucil A24
F 5 95% Doucil A24
G 10 Pyramid 95
H 10 Sodium Carbonate
The granules coded G and H contain inorganic materials which are water soluble
and
'~ as such are not within the scope of the present invention. These particular
Examples are
included for comparative purposes.
A series of tablets were prepared at a standard density of 1325 ~10kg/m3.
Tablets 1A
to 1 H contain 2% by weight of granules A to H respectively, the other 98%
being formed from
concentrated Persil original non-Biological detergent powder. Tablet 1J was
fabricated entirely
from the same Persil powder. Tablets 1 K and 1 L were prepared from the same
Persil powder,
but incorporated 0.2% and 2% by weight of Aquasorb A500 powder respectively.
Table 3 shows the level of disintegration and the conductivity obtained after
10
minutes immersion in water for these tablets using the experimental protocol
described above in
Method 1. The conductivity measurements are representative of the degree of
dissolution of the
soluble ionic constituents of the Persil detergent powder, the higher the
conductivity value the
greater the degree of tablet dissolution. The measurement of disintegration
shows the level of
undisintegrated residue retained in the 'cage'. Thus a high value indicates a
poorly
disintegrating tablet.
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TABLE 3
Tablet Code Conductivity (microSiemen)Undisintegrated Residue
(%)
1 A 3800 5
1 g 4100 0
1 C 4000 0
1 D 3970 0
1 E 3700 2
1 F 3520 10
1 G 1060 84
1 H 2840 29
1J 1720 49
1 K 1800 48
1L 630 80
The data clearly demonstrate the following:
1) The Tablet 1J, composed entirely of concentrated Persil powder, does not
disintegrate or
dissolve well; after 10 minutes it is only about 50% disintegrated.
2) Addition of 0.2% Aquasorb A500 (Tablet 1 K) has no appreciable effect (this
is equivalent to
the amount of Aquasorb added via granule incorporation in Tablets 1 A to 1 D,
1 G and 1 H).
3) Addition of more Aquasorb in Tablet 1 L (equivalent to the total weight
addition of granules in
Tablets 1A-1H) appears to suppress disintegration and dissolution.
4) Tablets 1A-1 D are essentially fully disintegrated/dissolved after 10
minutes.
5) In contrast, when the Aquasorb has been co-granulated with a soluble
material (Tablets 1G,
1 H), the disintegration and dissolution is far less effective. In the case of
silicate, the
granules actually appear to retard disintegration relative to Tablet 1 J.
6) Even when the level of Aquasorb in the granules is reduced to 7.5% or 5%
(Tablets 1 E, 1 F,
respectively) disintegration of the tablets is very well advanced after 10
minutes.
EXAMPLE 2
Table 4 below shows data for Tablets 2E, 2F equivalent to the data in Table 3.
These
tablets which are similar to the tablets used in Example 1 but contain
granules E and F
respectively, incorporated into tablets at 4% by weight instead of 2%. The
test method for
measuring disintegration was Method 1. Again, it is clear that, by increasing
the weight of
granule in the tablet at these lower levels of Aquasorb inclusion, the
excellent disintegrating
properties of the granules can be retained without the need to significantly
increase the total
weight of disintegrating polymer in the tablet (since 4% inclusion of granule
F corresponds to
2% of granule D in terms of the total weight of Aquasorb introduced into the
granule).
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TABLE 4
Tablet Code Conductivity (microSiemen)Undisintegrated
Residue (%)
2E 3950 0
2F 3900 0
EXAMPLE 3
Table 5 below shows further data for disintegration/conductivity (using
disintegration
Method 1 ) for tablets containing various of the granules, again incorporated
into the tablets at
2% by weight. These tablets are identified as 3X, where the X is the letter
corresponding to the
granule identity in Table 2. In this case, the tablets have been prepared at a
higher density
(1350 ~ 10 kg/m3). At this higher density, it is possible to discriminate
between the performance
of the different granules A to D. From this data, it appears that the zeolite-
containing granules
are preferred over the silica-containing variant, with the granules prepared
from Doucil A24
being the best performing disintegrating agents.
TABLE 5
Tablet Code Conductivity (microSiemen)Undisintegrated
Residue (%)
3A 3060 21
3g 3500 9
3C 3060 13
3D 3860 9
EXAMPLE 4
A number of tablets were prepared using a standard detergent base powder,
similar
to concentrated Persil powder, but without minor additives, such as perfume.
Tablets containing
disintegrant granules as shown in Table 6 below were prepared at a nominal
density of
1250 kg/m3 with 5% by weight of granules in the final detergent composition.
The disintegrant
granules used were all based on the zeolite P, Doucil A24, which consisted of
90%
aluminosilicate and 10% water by weight.
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TABLE 6
Granule Water-swellable agent in granule
Code (% by weight)
4M Aquasorb A500 (7.5)
4N Ac-Di-Sol' (5.0)
40 Ac-Di-Sol' (7.5)
4P Ac-Di-Sol' (10.0)
4Q Ac-Di-Sol' (15.0)
4R Cellulose powder BFT' Fines (7.5)
4S National 78- 1551' (7.5)
4T Arbocel FT40" (7.5)
'Ac-Di-Sol is a croscarmellulose sodium available from FMC Corporation,
Philadelphia USA.
ZCellulose powder BFT is a granulated sulphite cellulose available from
Vendico Chemical AB,
Malmo, Sweden.
3National 78-1551 is a pre-gelatinised starch available from National Starch &
Chemical,
Manchester, UK.
'Arbocel FT40 is a fibrous natural cellulose available from J. Rettenmaier &
Sohne, Rosenberg,
Germany.
The disintegration of the tablets was measured using Method 2, described
hereinbefore, and the results are given in Table 7 below.
TABLE 7
Disintegrant code Undisintegrated residue
(%w/w)
4M 40
4N 42
40 32
4P 36
4Q 34
4R 33
4S 32
4T 43
no disintegrant 87
In general, the amount of residue found using Method 2 is larger than that
found
using Method 1, but the results still clearly demonstrate that the tablets
containing disintegrant
granules disintegrate to a much larger extent than tablets containing no
granules.
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