Note: Descriptions are shown in the official language in which they were submitted.
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PRODUCTION PROCESS FOR DETERGENT TABLET
The present invention relates to a process for producing detergent tablets.
Detergent tablets are now widely used in auto-dish washing application, and
are
starting to be used in laundry applications. These tablets are produced by
industrial processes which typically involve compressing a particulate
material
into a tablet form, the particulate material being typically formed from a
detergent
composition.
The present invention concerns a process for making a detergent tablet, the
process comprising a first step of providing a detergent composition, a second
step of forming a particulate material comprising the detergent composition,
and
2o a third step of compressing the particulate material in a tablet form. Such
a
process is known from EP-A2-0 711 828.
Among the advantage of such processes is that it allows to produce relatively
solid tablets based on classic detergent powders, thus reducing the messiness
induced by handling of detergent compositions in a fluid form (powder,
granules,
liquid, gels or paste) while having a tablet form which remains based on
technologies already developed for particulate materials. Further tablets
provide
additional dosing accuracy by avoiding over-dosing or under-dosing.
3o While having these and other advantages, the detergent tablets obtained by
such
processes have disadvantages. For example, the compression of the particulate
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material leads to dissolution characteristics which are difficult to maintain
compared to detergent compositions in a fluid form.
The invention seeks to provide a process for making a detergent tablet of the
above mentioned kind which leads to detergent tablets having improved
dissolution characteristics, while maintaining the mechanical integrity of the
tablets.
Summary of the Invention
In accordance with the invention, this object is accomplished in a process of
the
above mentioned kind in that it further comprises a step of cooling the
detergent
composition below ambient temperature between the first and the third step.
Detailed Description of the Invention
The invention relates to a process for making a detergent tablet. By a tablet,
it
should be understood a solid block, which may take various shapes, and have
various sizes. By a detergent tablet, it should be understood a tablet
containing
2o detergent, i.e. typically containing surfactants. This type of tablet is
usually used
for cleaning purposes.
The process of the invention comprises a first step of providing a detergent
composition. The detergent composition may be provided in various forms, and
comprise a mixture of different materials. The process also comprises a second
2s step of forming a particulate material comprising the detergent
composition. The
particulate material may be formed in different ways, which are exemplified
below. It should be noted that the particulate material comprises the
detergent
composition but may also comprise other ingredients. The process further
comprises a third step of compressing the particulate material in a tablet
form.
3o Again, various ways to obtain a tablet by compressing a particulate
material are
described hereby, although other ways may be useful.
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The process is characterised in that it further comprises a step of cooling
the
detergent composition below ambient temperature between the first and the
third
step. The ambient temperature is considered to be the ambient temperature on
the production side in the tabletting area. For example, this ambient
temperature
is the ambient temperature in the surroundings of the tabletting machine. It
should be noted that in particular cases, for example in the summer, the
ambient
temperature of a production site can reach relatively high temperatures, often
above 25°C, sometimes above 30°C. The process according to the
invention was
o found particularly useful in such high temperature environments. Indeed, in
a
preferred embodiment, the ambient temperature is of more than 18°C,
even
more preferably of more than 20°C. By cooling below ambient
temperature, it
should be understood that sometime between the first and the third step, the
detergent composition is being brought to a temperature which is below the
~5 ambient temperature. The cooling may take place anytime between the first
and
third step, for example in storage silos, in spray drum machines, in Loedige
KM
machines, or during storage between the second and the third step for example.
Indeed, in a preferred embodiment, the step of cooling the detergent
composition
consists in exposing the detergent composition to a temperature below ambient
2o temperature in a portion of space. However, other means of cooling may also
be
used, such as de-pressurisation for example. Even more preferably, the
exposition is provided by placing or displacing the detergent composition in
or
through the portion of space in which the temperature is below ambient
temperature for a given exposition time. This may be achieved for example by
25 placing the detergent composition in a silo, whereby the temperature inside
of the
silo is below ambient temperature, or by displacing the detergent composition
through a cooling tunnel at some stage during the process, or simply by having
a
cooling air current situated on the production line. Cooling may also be
provided
by means of liquid nitrogen or solid C02, the advantage of the use of such
so products being that they are chemically neutral as they normally do not
react with
a detergent composition, and that they are vaporising as soon as released in
the
ambient temperature.
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It should be noted that the process according to the invention was found
particularly useful for cooling a detergent composition which is at a
temperature
above ambient temperature prior to the cooling step. Indeed, even though the
ambient temperature will lower the temperature of the detergent composition
having a temperature above ambient, such a detergent composition will be
cooled faster by applying a temperature under ambient temperature as described
in the process of the invention. This particular aspect may be useful in a
wide
range of ambient temperature, i.e. an ambient temperature of at least
5°C, more
preferably of at least 10°C, and even more preferably of at least
15°C. Further, it
should be noted that the cooling step is rendered even more efficient when the
cooling is provided by a stream, the stream being formed either by projecting
a
liquid (N2 for example) or gaseous (air for example) fluid , or even solid
such as
C02 onto the detergent composition, or by having the detergent composition
displaced through such a fluid, or by a combination of both, in order to
increase
the heat transfer between the cooling gaseous or liquid fluid and the
detergent
composition.
The process according to the invention is preferred when the difference of
2o temperature between the ambient temperature and the temperature below
ambient temperature is of at least 3°C, more preferably of at least
5°C. It is even
more preferred with a difference of at least 10°C.
In an other preferred embodiment, the exposition time is proportional to the
2s weight of detergent composition exposed divided by the difference of
temperature between the ambient temperature and the temperature below
ambient temperature of the cooling step. For example, in a production line
having
a debit of from 5 tons per hour up to 100 tons an hour (preferably of at least
10
tons per hour and of less than 65 tons per hour) of detergent composition, the
so detergent composition is preferably exposed for 30 seconds to a steam of
liquid
nitrogen, the steam ,of liquid nitrogen having a debit of from 2 and up to 10
tons
per hour.
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In a preferred embodiment, the detergent composition comprises at least 10% by
weight of surfactant, more preferably at least 15% of surfactant, even more
preferably more than 20% of surfactant, or at least 2% by weight of binder,
more
5 preferably at least 3% of binder, even more preferably at least 5% of binder
and
most preferably at least 7% of binder. Indeed, without wishing to be bound by
theory, it is believed that the improved disintegration of the tablet
according to the
invention may be due to a morphological change of one of these ingredients due
to the temperature difference.
In a most preferred embodiment, the detergent composition has a temperature
below ambient temperature after the cooling step and before the third step,
this
being due to the cooling of the detergent composition. Preferably, the
detergent
composition has a temperature of at least 2°C below ambient
temperature, more
preferably 5°C and most preferably 10°C.
A tablet obtainable by the process of the invention was found to dispense more
readily.
2o The tablets may comprise components such as fragrance, surfactants,
enzymes,
detergent etc.... Typical tablet compositions for the preferred embodiment of
the
present invention are disclosed in the pending European applications of the
Applicant n° 96203471.6, 96203462.5, 96203473.2 and 96203464.1 for
example. Elements typically entering in the composition of detergent tablets
or of
other forms of detergents such as liquids or granules are detailed in the
following
paragraphs.
Highly soluble Compounds
3o The tablet may comprise a highly soluble compound. Such a compound could be
formed from a mixture or from a single compound. A highly soluble compound is
defined as follow:
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A solution is prepared as follows comprising de-ionised water as well as 20
grams per litre of a specific compound:
1- 20 g of the specific compound is placed in a Sotax Beaker. This beaker is
placed in a constant temperature bath set at 10°C. A stirrer with a
marine
propeller is placed in the beaker so that the bottom of the stirrer is at 5 mm
above the bottom of the Sotax beaker. The mixer is set at a rotation speed of
200 turns per minute.
2- 980 g of the de-ionised water is introduced into the Sotax beaker.
3- 10 s after the water introduction, the conductivity of the solution is
measured,
1o using a conductivity meter.
4- Step 3 is repeated after 20, 30, 40, 50, 1 min, 2 min, 5 min and 10 min
after
step 2.
5- The measurement taken at 10 min is used as the plateau value or maximum
value.
~5 The specific compound is highly soluble according to the invention when the
conductivity of the solution reaches 80% of its maximum value in less than 10
seconds, starting from the complete addition of the de-ionised water to the
compound. Indeed, when monitoring the conductivity in such a manner, the
conductivity reaches a plateau after a certain period of time, this plateau
being
2o considered as the maximum value. Such a compound is preferably in the form
of
a flowable material constituted of solid particles at temperatures comprised
between 10 and 80°Celsius for ease of handling, but other forms may be
used
such as a paste or a liquid.
Example of highly soluble compounds include Sodium di isoalkylbenzene
25 sulphonate (DIBS) or Sodium toluene sulphonate for example.
Cohesive Effect
3o The tablet may. comprise a compound having a Cohesive Effect on the
particulate material of a detergent matrix forming the tablet. The Cohesive
Effect
on the particulate material of a detergent matrix forming the tablet or a
layer of
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the tablet is characterised by the force required to break a tablet or layer
based
on the examined detergent matrix pressed under controlled compression
conditions. For a given compression force, a high tablet or layer strength
indicates that the granules stuck highly together when they were compressed,
so
that a strong cohesive effect is taking place. Means to assess tablet or layer
strength (also refer to diametrical fracture stress) are given in
Pharmaceutical
dosage forms : tablets volume 1 Ed. H.A. Lieberman et al, published in 1989.
The cohesive effect is measured by comparing the tablet or layer strength of
the
original base powder without compound having a cohesive effect with the tablet
or layer strength of a powder mix which comprises 97 parts of the original
base
powder and 3 parts of the compound having a cohesive effect. The compound
having a cohesive effect is preferably added to the matrix in a form in which
it is
substantially free of water (water content below 10% (pref. below 5%)). The
temperature of the addition is between 10 and 80C, more pref. between 10 and
40C.
A compound is defined as having a cohesive effect on the particulate material
according to the invention when at a given compacting force of 3000N, tablets
with a weight of 50g of detergent particulate material and a diameter of 55mm
have their tablet tensile strength increased by over 30% (preferably 60 and
more
2o preferably 100%) by means of the presence of 3% of the compound having a
cohesive effect in the base particulate material.
An example of a compound having a cohesive effect is Sodium di
isoalkylbenzene sulphonate.
When integrating a highly soluble compound having also a cohesive effect on
the
particulate material used for a tablet or layer formed by compressing a
particulate material comprising a surfactant, the dissolution of the tablet or
layer
in an aqueous solution is significantly increased. In a preferred embodiment,
at
least 0.5% per weight of a tablet or layer is formed from the highly soluble
compound, more preferably at least 0.75%, even more preferably at least 2%
3o and most preferably at least 4% per weight of the tablet or layer being
formed
from the highly soluble compound having a cohesive effect on the particulate
material.
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It should be noted that a composition comprising a highly soluble compound as
well as a surfactant is disclosed in EP-A-0 524 075, this composition being a
liquid composition.
A highly soluble compound having a cohesive effect on the particulate material
allows to obtain a tablet having a higher tensile strength at constant
compacting
force or an equal tensile strength at lower compacting force when compared to
traditional tablets. Typically, a whole tablet will have a tensile strength of
more
than SkPa, preferably of more than 10kPa, more preferably, in particular for
use
in laundry applications, of more than 15kPa, even more preferably of more than
~0 30 kPa and most preferably of more than 50 kPa, in particular for use in
dish
washing or auto dish washing applications; and a tensile strength of less than
300 kPa, preferably of less than 200 kPa, more preferably of less than 100
kPa,
even more preferably of less than 80 kPa and most preferably of less than 60
kPa. Indeed, in case of laundry application, the tablets should be less
~5 compressed than in case of auto dish washing applications for example,
whereby
the dissolution is more readily achieved, so that in a laundry application,
the
tensile strength is preferably of less than 30 kPa.
This allows to produce tablets or layers which have a solidity and mechanical
resistance comparable to the solidity or mechanical resistance of traditional
2o tablets while having a less compact tablet or layer thus dissolving more
readily.
Furthermore, as the compound is highly soluble, the dissolution of the tablet
or
layer is further facilitated, resulting in a synergy leading to facilitated
dissolution
for a tablet according to the invention.
Tablet Manufacture
The tablet may comprise several layers. For the purpose of manufacture of a
single layer, the layer may be considered as a tablet itself.
3o Detergent tablets can be prepared simply by mixing the solid ingredients
together
and compressing the mixture in a conventional tablet press as used, for
example, in the pharmaceutical industry. Preferably the principal ingredients,
in
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particular gelling surfactants, are used in particulate form. Any liquid
ingredients,
for example surfactant or suds suppressor, can be incorporated in a
conventional
manner into the solid particulate ingredients.
In particular for laundry tablets, the ingredients such as builder and
surfactant
can be spray-dried in a conventional manner and then compacted at a suitable
pressure. Preferably, the tablets according to the invention are compressed
using a force of less than 100000N, more preferably of less than 50000N, even
more preferably of less than 5000N and most preferably of less than 3000 N.
Indeed, the most preferred embodiment is a tablet suitable for laundry
~o compressed using a force of less than 2500N, but tablets for auto dish
washing
may also be considered for example, whereby such auto dish washing tablets
are usually more compressed than laundry tablets.
The particulate material used for making a tablet can be made by any
particulation or granulation process. An example of such a process is spray
15 drying (in a co-current or counter current spray drying tower) which
typically gives
low bulk densities 600g/I or lower. Particulate materials of higher density
can be
prepared by granulation and densification in a high shear batch
mixer/granulator
or by a continuous granulation and densification process (e.g. using Lodige~
CB
and/or Lodige~ KM mixers). Other suitable processes include fluid bed
2o processes, compaction processes (e.g. roll compaction), extrusion, as well
as
any particulate material made by any chemical process like flocculation,
crystallisation sentering, etc. Individual particles can also be any other
particle,
granule, sphere or grain.
The components of the particulate material may be mixed together by any
25 conventional means. Batch is suitable in, for example, a concrete mixer,
Nauta
mixer, ribbon mixer or any other. Alternatively the mixing process may be
carried
out continuously by metering each component by weight on to a moving belt, and
blending them in one or more drums) or mixer(s). Non-gelling binder can be
sprayed on to the mix of some, or all of, the components of the particulate
3o material. Other liquid ingredients may also be sprayed on to the mix of
components either separately or premixed. For example perfume and slurries of
optical brighteners may be sprayed. A finely divided flow aid (dusting agent
such
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as zeolites, carbonates, silicas) can be added to the particulate material
after
spraying the binder, preferably towards the end of the process, to make the
mix
less sticky.
The tablets may be manufactured by using any compacting process, such as
5 tabletting, briquetting, or extrusion, preferably tabletting. Suitable
equipment
includes a standard single stroke or a rotary press (such as Courtoy~, Korch~,
Manesty~, or Bonals~). The tablets prepared according to this invention
preferably have a diameter of between 20mm and 60mm, preferably of at least
35 and up to 55 mm, and a weight between 25 and 100 g. The ratio of height to
1o diameter (or width) of the tablets is preferably greater than 1:3, more
preferably
greater than 1:2. In another preferred embodiment, the tablets have a square
cross-section of 45 mm by 45 mm and are 25 mm high. The compaction
pressure used for preparing these tablets need not exceed 100000 kN/m2,
preferably not exceed 30000 kN/m2, more preferably not exceed 5000 kN/m2,
even more preferably not exceed 3000kN/m2 and most preferably not exceed
1000kN/m2. In a preferred embodiment according to the invention, the tablet
has
a density of at least 0.9 g/cc, more preferably of at least 1.0 g/cc, and
preferably
of less than 2.0 g/cc, more preferably of less than 1.5 g/cc, even more
preferably
of less than 1.25 g/cc and most preferably of less than 1.15 g/cc.
2o Multi layered tablets are typically formed in rotating presses by placing
the
particulate material of each layer, one after the other in force feeding
flasks. As
the process continues, the particulate material layers are then pressed
together
in the pre-compression and compression stages stations to form the multilayer
tablet. With some rotating presses it is also possible to compress the first
feed
2s layer before compressing the whole tablet.
so Hydrotrope compound
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A highly soluble compound having a cohesive effect may be integrated to a
detergent tablet, whereby this compound is also a hydrotrope compound. Such
hydrotrope compound may be generally used to favour surfactant dissolution by
avoiding gelling. A specific compound is defined as being hydrotrope as
follows
s (see S.E. Friberg and M. Chiu, J. Dispersion Science and Technology, 9(5&6),
pages 443 to 457, (1988-1989)):
1. A solution is prepared comprising 25% by weight of the specific compound
and 75% by weight of water.
2. Octanoic Acid is thereafter added to the solution in a proportion of 1.6
times
1o the weight of the specific compound in solution, the solution being at a
temperature of 20°Celsius. The solution is mixed in a Sotax beaker with
a stirrer
with a marine propeller, the propeller being situated at about 5mm above the
bottom of the beaker, the mixer being set at a rotation speed of 200 rounds
per
minute.
15 3. The specific compound is hydrotrope if the the Octanoic Acid is
completely
solubilised, i.e . if the solution comprises only one phase, the phase being a
liquid phase.
It should be noted that in a preferred embodiment of the invention, the
hydrotrope compound is a flowable material made of solid particles at
operating
2o conditions between 15 and 60° Celsius.
Hydrotrope compounds include the compounds listed thereafter:
A list of commercial hydrotropes could be found in McCutcheon's Emulsifiers
and
Detergents published by the McCutcheon division of Manufacturing
Confectioners Company. Compounds of interest also include:
25 1. Nonionic hydrotrope with the following structure:
R - O - (CH2CH20)x( CH -CH20)yH
CH3
where R is a C8-C10 alkyl chain, x ranges from 1 to 15, y from 3 to 10.
2. Anionic hydrotropes such as alkali metal aryl sulfonates. This includes
alkali
metal salts of benzoic acid, salicylic acid, bezenesulfonic acid and its many
3o derivatives, naphthoic acid and various hydroaromatic acids. Examples of
these
are sodium, potassium and ammonium benzene sulfonate salts derived from
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toluene sulfonic acid, xylene sulfonic acid, cumene sulfonic acid, tetralin
sulfonic
acid, naphtalene sulfonic acid, methyl- naphtalene sulfonic acid, dimethyl
naphtalene sulfonic acid, trimethyl naphtalene sulfonic acid=
Other examples include salts of dialkyl benzene sulfonic acid such as salts of
di
isopropyl benzene sulfonic acid, ethyl methyl benzene sulfonic acid, alkyl
benzene sulfonic acid with an alkyl chain length with 3 to 10, (pref. 4 to 9),
linear
or branched alkyl sulfonates with an alkyl chain with 1 to 18 carbons.
3. Solvent hydrotropes such as alkoxylated glycerines and alkoxylated
glycerides, esters slakoxylated glycerines, alkoxylated fatty acids, esters of
1o glycerin, polyglycerol esters. Preferred alkoxylated glycerines have the
following
structure:
R
CHp-0(-0H2CH-0-~"H
R
CHz-O(-0HzCH-0-~"H
R
CHZ-O(-CH2CH-0-~,H
where I, m and n are each a number from 0 to about 20, with I+m+n = from about
2 to about 60, preferably from about 10 to about 45 and R represents H, CH3 or
C2H5
Preferred alkoxylated glycerides have the following struture
HZ~-R,
H RZ R3
Hp~-O-(CHp~H-O~H
where R1 and R2 are each CnC00 or -(CH2CHR3-O),-H where R3 = H, CH3 or
C2H5 and I is a number from 1 to about 60, n is a number from about 6 to about
24.
4. Polymeric hydrotropes such as those described in EP636687:
R R~
-(CHZ- )x - (CHZ- )y-
E RZ
where E is a hydrophilic functional group,
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R is H or a C1-C10 alkyl group or is a hydrophilic functional group;
R1 is H a lower alkyl group or an aromatic group,
R2 is H or a cyclic alkyl or aromatic group.
The polymer typically has a molecular weight of between about 1000 and
1000000.
5. Hydrotrope of unusual structure such as 5-carboxy-4-hexyl-2-cyclohexene-1-
yl
octanoic acid (Diacid~)
Use of such compound in the invention would further increase the dissolution
rate of the tablet, as a hydrotrope compound facilitates dissolution of
surfactants,
1o for example. Such a compound could be formed from a mixture or from a
single
compound.
Tensile Strength
For the purpose of measuring tensile strength of a layer, the layer may be
considered as a tablet itself.
Depending on the composition of the starting material, and the shape of the
tablets, the used compacting force may be adjusted to not affect the tensile
2o strength, and the disintegration time in the washing machine. This process
may
be used to prepare homogenous or layered tablets of any size or shape.
For a cylindrical tablet, the tensile strength corresponds to the diametrical
fracture stress (DFS) which is a way to express the strength of a tablet or
layer,
and is determined by the following equation
Tensile strength = 2 F/ ~Dt
Where F is the maximum force (Newton) to cause tensile failure (fracture)
measured by a VK 200 tablet hardness tester supplied by Van Kell industries,
Inc. D is the diameter of the tablet or layer, and t the thickness of the
tablet or
layer. For a non round tablet, ~D may simply be replaced by the perimeter of
the
tablet.
(Method Pharmaceutical Dosage Forms : Tablets Volume 2 Page 213 to 217).
A tablet having a diametral fracture stress of less than 20 kPa is considered
to
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be fragile and is likely to result in some broken tablets being delivered to
the
consumer. A diametral fracture stress of at least 25 kPa is preferred.
This applies similarly to' non cylindrical tablets, to define the tensile
strength,
whereby the cross section normal to the height of the tablet is non round, and
whereby the force is applied along a direction perpendicular to the direction
of
the height of the tablet and normal to the side of the tablet, the side being
perpendicular to the non round cross section.
1 o Tablet Dispensing
The rate of dispensing of a detergent tablet can be determined in the
following
way:
Two tablets, nominally 50 grams each, are weighed, and then placed in the
dispenser of a Baucknecht~ WA9850 washing machine. The water supply to the
washing machine is set to a temperature of 20 °C and a hardness of 21
grains
per gallon, the dispenser water inlet flow-rate being set to 8 I/min. The
level of
tablet residues left in the dispenser is checked by switching the washing on
and
the wash cycle set to wash program 4 (white/colors, short cycle). The
dispensing
2o percentage residue is determined as follows:
dispensing = residue weight x 100 / original tablet weight
The level of residues is determined by repeating the procedure 10 times and an
average residue level is calculated based on the ten individual measurements.
In
this stressed test a residue of 40 % of the starting tablet weight is
considered to
be acceptable. A residue of less than 30% is preferred, and less than 25% is
more preferred.
It should be noted that the measure of water hardness is given in the
traditional
"grain per gallon" unit, whereby 0.001 mole per litre = 7.0 grain per gallon,
representing the concentration of Ca2+ ions in solution.
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Effervescent
Detergent tablets may further comprise an effervescent.
5 Effervescency as defined herein means the evolution of bubbles of gas from a
liquid, as the result of a chemical reaction between a soluble acid source and
an
alkali metal carbonate, to produce carbon dioxide gas,
i.e. CgH807 + 3NaHC03 ~ NagC6H507 + 3C02 T + 3H20
Further examples of acid and carbonate sources and other effervescent systems
1o may be found in : (Pharmaceutical Dosage Forms : Tablets Volume 1 Page 287
to 291 ).
An effervescent may be added to the tablet mix in addition to the detergent
ingredients. The addition of this effervescent to the detergent tablet
improves the
disintegration time of the tablet. The amount will preferably be between 5 and
20
15 % and most preferably between 10 and 20% by weight of the tablet.
Preferably
the effervescent should be added as an agglomerate of the different particles
or
as a compact, and not as separated particles.
Due to the gas created by the effervescency in the tablet, the tablet can have
a
higher D.F.S. and still have the same disintegration time as a tablet without
2o effervescency. When the D.F.S. of the tablet with effervescency is kept the
same as a tablet without, the disintegration of the tablet with effervescency
will
be faster.
Further dissolution aid could be provided by using compounds such as sodium
acetate or urea. A list of suitable dissolution aid may also be found in
Pharmaceutical Dosage Forms: Tablets, Volume 1, Second edition, Edited by
H.A. Lieberman et all, ISBN 0-8247-8044-2.
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Coating
Solidity of a tablet may be improved by making a coated tablet, the coating
covering a non-coated tablet, thereby improving the mechanical characteristics
of
the tablet.
This very advantageously applies to multi-layer tablets, whereby the
mechanical
characteristics of a more elastic layer can be transmitted via the coating to
the
rest of the tablet, thus combining the advantage of the coating with the
1o advantage of the more elastic layer. Indeed, mechanical constraints will be
transmitted through the coating, thus improving mechanical integrity of the
tablet.
In one embodiment of the present invention, the tablets may then be coated so
that the tablet does not absorb moisture, or absorbs moisture at only a very
slow
rate. The coating is also strong so that moderate mechanical shocks to which
the
tablets are subjected during handling, packing and shipping result in no more
than very low levels of breakage or attrition. Finally the coating is
preferably
brittle so that the tablet breaks up quickly when subjected to stronger
mechanical
shock. Furthermore it is advantageous if the coating material is dissolved
under
alkaline conditions, or is readily emulsified by surfactants. This contributes
to
2o avoiding the problem of visible residue in the window of a front-loading
washing
machine during the wash cycle, and also avoids deposition of undissolved
particles or lumps of coating material on the laundry load.
Water solubility is measured following the test protocol of ASTM E1148-87
entitled, "Standard Test Method for Measurements of Aqueous Solubility".
The coating material has a melting point preferably of from 40 °C to
200 °C.
The coating can be applied in a number of ways. Two preferred coating methods
are a) coating with a molten material and b) coating with a solution of the
material.
In a), the coating material is applied at a temperature above its melting
point, and
so solidifies on the tablet. In b), the coating is applied as a solution, the
solvent
being dried to leave, a coherent coating. The substantially insoluble material
can
be applied to the tablet by, for example, spraying or dipping. Normally when
the
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17
molten material is sprayed on to the tablet, it will rapidly solidify to form
a
coherent coating. When tablets are dipped into the molten material and then
removed, the rapid cooling again causes rapid solidification of the coating
material. During the solidification phase, the coating undergoes some internal
s stress (e.g. shrinkage upon cooling) and external stress (e.g. tablet
relaxation).
This will likely cause some cracks in the structure such as edge splitting if
the
coating material is too brittle to withstand these mechanical stress, which is
often
the case when a coating is solely made from components solid at 25°C.
Indeed,
it is preferred that the coating comprises a component which is liquid at
25°C. It
1o is believed that this liquid component will allow the coating to better
withstand
and absorb mechanical stress by rendering the coating structure more flexible.
The component which is liquid at 25°C is preferably added to the
coating
materials in proportions of less than 10% by weight of the coating, more
preferably less than 5% by weight, and most preferably of less than 3% by
1s weight. The component which is liquid at 25°C is preferably added to
the coating
materials in proportions of more than 0.1 % by weight of the coating, more
preferably more than 0.3% by weight, and most preferably of more than 0.5% by
weight. Further preferred is the addition of reinforcing fibres to the coating
in
order to further reinforce the structure.
2o Preferably, the coating comprises a crystallised structure. By
crystallised, it
should be understood that the coating comprises a material which is solid at
ambient temperature (25°C) and has a structure exhibiting some order.
This can
be detected typically by usual crystallography techniques e.g. X-ray analysis,
on
the material itself. In a more preferred embodiment, the material forming the
25 crystallised structure does not co-crystallised or only partially with the
optional
component which is liquid at 25°C mentioned above. Indeed, it is
preferred that
the optional component remains in the liquid state at 25°C in the
coating
crystalline structure in order to provide flexibility to the structure and
resistance to
mechanical stress. In another embodiment, the optional component which is
30 liquid at 25°C may advantageously have a functionality in the
washing of laundry,
for example silicone oil which provides suds suppression benefits or perfume
oil..
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The coating may also comprise other optional components. Suitable coating
materials are for example dicarboxylic acids. Particularly suitable
dicarboxylic
acids are selected from the group consisting of oxalic acid, malonic acid,
succinic
acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid,
sebacic
s acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid and
mixtures
thereof. Most preferred is adipic acid.
Clearly substantially insoluble materials having a melting point below 40
°C are
often not sufficiently solid at ambient temperatures and it has been found
that
materials having a melting point above about 200 °C are not practicable
to use.
1o Preferably, an acid having a melting point of more than 90°C such as
azelaic,
sebacic acid, dodecanedioic acid is used. It is even more preferred to use an
acid having a melting point of more than 145°C such as adipic acid.
By "melting point" is meant the temperature at which the material when heated
slowly in, for example, a capillary tube becomes a clear liquid.
~5 A coating of any desired thickness can be applied according to the present
invention. For most purposes, the coating forms from 1 % to 10%, preferably
from 1.5% to 5%, of the tablet weight.
Tablet coatings are very hard and provide extra strength to the tablet.
Examples of optional components which are liquid at 25° are
including
2o PolyEthylene Glycols, thermal oil, silicon oil, esters of dicarboxylic
acids, mono
carboxylic acids, paraffin, triacetin, perfumes or alkaline solutions. It is
preferred
that the structure of the components which is liquid at 25°C is close
to the
material forming the crystallised structure, so that the structure is not
excessively
disrupted. In a most preferred embodiment, the crystallised structure is made
of
2s adipic acid, the component which is liquid at 25°C being available
under the
name CoasoIT"" from Chemoxy International, being a blend of the di-isobutyl
esters of the glutaric, succinic and adipic acid. The advantage of the use of
this
component being the good dispersion in the adipic acid to provide flexibility.
It
should be noted that disintegration of the adipic acid is further improved by
the
so adipate content of CoasoIT"".
Fracture of the coating in the wash can be improved by adding a disintegrant
in
the coating. This disintegrant will swell once in contact with water and break
the
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19
coating in small pieces. This will improve the dissolution of the coating in
the
wash solution. The disintegrant is suspended in the coating melt at a level of
up
to 30%, preferably between 5% and 20%, most preferably between 5 and 10%
by weight. Possible disintegrants are described in Handbook of Pharmaceutical
Excipients (1986). Examples of suitable disintegrants include starch: natural,
r~iodified or pregelatinized starch, sodium starch gluconate; gum: agar gum,
guar
gum, locust bean gum, karaya gum, pectin gum, tragacanth gum; croscarmylose
Sodium, crospovidone, cellulose, carboxymethyl cellulose, algenic acid and its
salts including sodium alginate, silicone dioxide, clay, polyvinylpyrrolidone,
soy
1o polysacharides, ion exchange resins, polymers containing cationic (e.g.
quaternary ammonium) groups, amine-substituted polyacrylates, polymerised
cationic amino acids such as poly-L-lysine, polyallylamine hydrochloride) and
mixtures thereof.
Preferably, the coating comprises an acid having a melting temperature of at
1s least 145°C, such as adipic acid for example, as well as a clay,
such as a
bentonite clay for example, whereby the clay is used as a disintegrant and
also
to render the structure of adipic acid more favourable for water penetration,
thus
improving the dispersion of the adipic acid in a aqueous medium. Preferred are
clays having a particle size of less than 75 Nm, more preferably of less than
53
2o Nm, in order to obtain the desired effect on the structure of the acid.
Preferred
are bentonite clays. Indeed the acid has a melting point such that traditional
cellulosic disintegrants undergo a thermal degradation during the coating
process, whereas such clays are found to be more heat stable. Further,
traditional cellulosic disintegrant such as NymceIT"" for example are found to
turn
2s brown at these temperatures.
In another preferred embodiment, the coating further comprises reinforcing
fibres. Such fibres have been found to improve further the resistance of the
coating to mechanical stress and minimise the splitting defect occurence. Such
fibres are preferably having a length of at least 100 Nm, more preferably of
at
so least 200 pm and most preferably of at least 250 um to allow structure
reinforcement. Such fibres are preferably having a length of at less than 500
Nm,
more preferably of less than 400 Nm and most preferably of less than 350 Nm in
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order not to impact onto dispersion of the coating in an aqueous medium.
Materials which may be used for these fibres include viscose rayon, natural
nylon, synthetic nylon (polyamides types 6 and 6,6), acrylic, polyester,
cotton and
derivatives of cellulose such as CMCs. Most preferred is a cellulosic material
s available under the trade mark Solka-FIocT"" from Fibers Sales &
Development. It
should be noted that such fibres do not normally need pre-compression for
reinforcing the coating structure. Such fibres are preferably added at a level
of
less than 5% by weight of the coating, more preferably less than 3% by weight.
Such fibres are preferably added at a level of more than 0.5% by weight of the
coating, more preferably more than 1 % by weight.
Detersive surfactants
~5 Surfactant are typically comprised in a detergent composition. The
dissolution of
surfactants is favoured by the addition of the highly soluble compound.
Nonlimiting examples of surfactants useful herein typically at levels from
about
1 % to about 55%, by weight, include the conventional C11 _C1 g alkyl benzene
sulfonates ("LAS") and primary, branched-chain and random C1 p_C20 alkyl
2o sulfates ("AS"), the C1p_C1g secondary (2,3) alkyl sulfates of the formula
CHg(CH2)x(CHOS03_M+) CH3 and CH3 (CH2)y(CHOS03_M+) CH2CH3 where
x and (y + 1 ) are integers of at least about 7, preferably at least about 9,
and M is
a water-solubilizing cation, especially sodium, unsaturated sulfates such as
oleyl
sulfate, the C10_C1g alkyl alkoxy sulfates ("AEXS"; especially EO 1-7 ethoxy
sulfates), C10_C1g alkyl alkoxy carboxylates (especially the EO 1-5
ethoxycarboxylates), the C10_18 glycerol ethers, the C10_C1g alkyl
polyglycosides and their corresponding sulfated polyglycosides, and C12_C18
alpha-sulfonated fatty acid esters. If desired, the conventional nonionic and
amphoteric surfactants such as the C12-C1 g alkyl ethoxylates ("AE") including
3o the so-called narrow peaked alkyl ethoxylates and Cg-C12 alkyl phenol
alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C12_C18
betaines and sulfobetaines ("sultaines"), C10_C1 g amine oxides, and the like,
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can also be included in the overall compositions. The C10-C1g N-alkyl
polyhydroxy fatty acid amides can also be used. Typical examples include the
C12-C1g N-methylglucamides. See WO 9,206,154. Other sugar-derived
surfactants include the N-alkoxy polyhydroxy fatty acid amides, such as C10-
C18
N-(3-methoxypropyl) glucamide. The N-propyl through N-hexyl C12-C18
glucamides can be used for low sudsing. C10-C20 conventional soaps may also
be used. If high sudsing is desired, the branched-chain C10-C1g soaps may be
used. Mixtures of anionic and nonionic surfactants are especially useful.
Other
conventional useful surfactants are listed in standard texts. In a preferred
1o embodiment, the tablet comprises at least 5% per weight of surfactant, more
preferably at least 15% per weight, even more preferably at least 25% per
weight, and most preferably between 35% and 45% per weight of surfactant.
Non gelling binders
Non gelling binders can be integrated in detergent compositions to further
facilitate dissolution.
If non gelling binders are used, suitable non-gelling binders include
synthetic
organic polymers such as polyethylene glycols, polyvinylpyrrolidones,
polyacrylates and water-soluble acrylate copolymers. The handbook of
Pharmaceutical Excipients second edition, has the following binders
classification: Acacia, Alginic Acid, Carbomer, Carboxymethylcellulose sodium,
Dextrin, Ethylcellulose, Gelatin, Guar gum, Hydrogenated vegetable oil type I,
Hydroxyethyl cellulose, Hydroxypropyl methylcellulose, Liquid glucose,
Magnesium aluminum silicate, Maltodextrin, Methylcellulose, polymethacrylates,
povidone, sodium alginate, starch and zein. Most preferable binders also have
an active cleaning function in the laundry wash such as cationic polymers,
i.e.
ethoxylated hexamethylene diamine quaternary compounds, bishexamethylene
3o triamines, or others such as pentaamines, ethoxylated polyethylene amines,
malefic acrylic polymers.
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22
Non-gelling binder materials are preferably sprayed on and hence have an
appropriate melting point temperature below 90°C, preferably below
70°C and
even more preferably below 50°C so as not to damage or degrade the
other
active ingredients in the matrix. Most preferred are non-aqueous liquid
binders
(i.e. not in aqueous solution) which may be sprayed in molten form. However,
they may also be solid binders incorporated into the matrix by dry addition
but
which have binding properties within the tablet.
Non-gelling binder materials are preferably used in an amount within the range
from 0.1 to 15% of the composition, more preferably below 5% and especially if
it
1o is a non laundry active material below 4% by weight of the tablet.
It is preferred that gelling binders, such as nonionic surfactants are avoided
in
their liquid or molten form. Nonionic surfactants and other gelling binders
are not
excluded from the compositions, but it is preferred that they be processed
into
the detergent tablets as components of particulate materials, and not as
liquids.
Builders
Detergent builders can optionally be included in the compositions herein to
assist
2o in controlling mineral hardness. Inorganic as well as organic builders can
be
used. Builders are typically used in fabric laundering compositions to assist
in
the removal of particulate soils.
The level of builder can vary widely depending upon the end use of the
composition.
Inorganic or P-containing detergent builders include, but are not limited to,
the
alkali metal, ammonium and alkanolammonium salts of polyphosphates
(exemplified by the tripolyphosphates, pyrophosphates, and glassy polymeric
meta-phosphates), phosphonates, phytic acid, silicates, carbonates (including
bicarbonates and sesquicarbonates), sulphates, and aluminosilicates. However,
3o non-phosphate builders are required in some locales. Importantly, the
compositions herein function surprisingly well even in the presence of the so-
called "weak" builders (as compared with phosphates) such as citrate, or in
the
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23
so-called "underbuilt" situation that may occur with zeolite or layered
silicate
builders.
Examples of silicate builders are the alkali metal silicates, particularly
those
having a Si02:Na20 ratio in the range 1.6:1 to 3.2:1 and layered silicates,
such
s as the layered sodium silicates described in U.S. Patent 4,664,839, issued
May
12, 1987 to H. P. Rieck. NaSKS-6 is the trademark for a crystalline layered
silicate marketed by Hoechst (commonly abbreviated herein as "SKS-6"). Unlike
zeolite builders, the Na SKS-6 silicate builder does not contain aluminum.
NaSKS-6 has the delta-Na2Si05 morphology form of layered silicate. It can be
prepared by methods such as those described in German DE-A-3,417,649 and
DE-A-3,742,043. SKS-6 is a highly preferred layered silicate for use herein,
but
other such layered silicates, such as those having the general formula
NaMSix02x+1 ~yH20 wherein M is sodium or hydrogen, x is a number from 1.9 to
4, preferably 2, and y is a number from 0 to 20, preferably 0 can be used
herein.
15 Various other layered silicates from Hoechst include NaSKS-5, NaSKS-7 and
NaSKS-11, as the alpha, beta and gamma forms. As noted above, the delta-
Na2Si05 (NaSKS-6 form) is most preferred for use herein. Other silicates may
also be useful such as for example magnesium silicate, which can serve as a
crispening agent in granular formulations, as a stabilizing agent for oxygen
2o bleaches, and as a component of suds control systems.
Examples of carbonate builders are the alkaline earth and alkali metal
carbonates as disclosed in German Patent Application No. 2,321,001 published
on November 15, 1973.
Aluminosilicate builders are useful in the present invention. Aluminosilicate
25 builders are of great importance in most currently marketed heavy duty
granular
detergent compositions, and can also be a significant builder ingredient in
liquid
detergent formulations. Aluminosilicate builders include those having the
empirical formula:
3o Mz(zA102)y]~xH20
wherein z and y are, integers of at least 6, the molar ratio of z to y is in
the range
from 1.0 to about 0.5, and x is an integer from about 15 to about 264.
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Useful aluminosilicate ion exchange materials are commercially available.
These
aluminosilicates can be crystalline or amorphous in structure and can be
naturally-occurring aluminosilicates or synthetically derived. A method for
producing aluminosilicate ion exchange materials is disclosed in U.S. Patent
3,985,669, Krummel, et al, issued October 12, 1976. Preferred synthetic
crystalline aluminosilicate ion exchange materials useful herein are available
under the designations Zeolite A, Zeolite P (B), Zeolite MAP and Zeolite X. In
an
especially preferred embodiment, the crystalline aluminosilicate ion exchange
material has the formula:
Nal2[(A102)12(Si02)121~xH20
wherein x is from about 20 to about 30, especially about 27. This material is
known as Zeolite A. Dehydrated zeolites (x = 0 - 10) may also be used herein.
Preferably, the aluminosilicate has a particle size of about 0.1-10 microns in
diameter.
~5 Organic detergent builders suitable for the purposes of the present
invention
include, but are not restricted to, a wide variety of polycarboxylate
compounds.
As used herein, "polycarboxylate" refers to compounds having a plurality of
carboxylate groups, preferably at least 3 carboxylates. Polycarboxylate
builder
can generally be added to the composition in acid form, but can also be added
in
2o the form of a neutralized salt. When utilized in salt form, alkali metals,
such as
sodium, potassium, and lithium, or alkanolammonium salts are preferred.
Included among the polycarboxylate builders are a variety of categories of
useful
materials. One important category of polycarboxylate builders encompasses the
ether polycarboxylates, including oxydisuccinate, as disclosed in Berg, U.S.
2s Patent 3,128,287, issued April 7, 1964, and Lamberti et al, U.S. Patent
3,635,830, issued January 18, 1972. See also "TMS/TDS" builders of U.S.
Patent 4,663,071, issued to Bush et al, on May 5, 1987. Suitable ether
polycarboxylates also include cyclic compounds, particularly alicvclic
compounds, such as those described in U.S. Patents 3,923,679; 3,835,163;
30 4,158,635; 4,120,874 and 4,102,903.
Other useful detergency builders include the ether hydroxypolycarboxylates,
copolymers of malefic anhydride with ethylene or vinyl methyl ether, 1, 3, 5-
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trihydroxy benzene-2, 4, 6-trisulphonic acid, and carboxymethyloxysuccinic
acid,
the various alkali metal, ammonium and substituted ammonium salts of
polyacetic acids such as ethylenediamine tetraacetic acid and nitrilotriacetic
acid,
as well as polycarboxylates such as mellitic acid, succinic acid,
oxydisuccinic
5 acid, polymaleic acid, benzene 1,3,5-tricarboxylic acid,
carboxymethyloxysuccinic
acid, and soluble salts thereof.
Citrate builders, e.g., citric acid and soluble salts thereof (particularly
sodium
salt), are polycarboxylate builders of particular importance for heavy duty
liquid
detergent formulations due to their availability from renewable resources and
~o their biodegradability. Citrates can also be used in granular compositions,
especially in combination with zeolite and/or layered silicate builders.
Oxydisuccinates are also especially useful in such compositions and
combinations.
Also suitable in the detergent compositions of the present invention are the
3,3-
15 dicarboxy-4-oxa-1,6-hexanedioates and the related compounds disclosed in
U.S.
Patent 4,566,984, Bush, issued January 28, 1986. Useful succinic acid builders
include the C5-C20 alkyl and alkenyl succinic acids and salts thereof. A
particularly preferred compound of this type is dodecenylsuccinic acid.
Specific
examples of succinate builders include: laurylsuccinate, myristylsuccinate,
2o palmitylsuccinate, 2-dodecenylsuccinate (preferred), 2-
pentadecenylsuccinate,
and the like. Laurylsuccinates are the preferred builders of this group, and
are
described in European Patent Application 86200690.5/0,200,263, published
November 5, 1986.
Other suitable polycarboxylates are disclosed in U.S. Patent 4,144,226,
25 Crutchfield et al, issued March 13, 1979 and in U.S. Patent 3,308,067,
Diehl,
issued March 7, 1967. See also Diehl U.S. Patent 3,723,322.
Fatty acids, e.g., C12-C1g monocarboxylic acids, can also be incorporated into
the compositions alone, or in combination with the aforesaid builders,
especially
citrate and/or the succinate builders, to provide additional builder activity.
Such
3o use of fatty acids will generally result in a diminution of sudsing, which
should be
taken into account by the formulator.
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26
In situations where phosphorus-based builders can be used, and especially in
the formulation of bars used for hand-laundering operations, the various
alkali
metal phosphates such as the well-known sodium tripolyphosphates, sodium
pyrophosphate and sodium orthophosphate can be used. Phosphonate builders
such as ethane-1-hydroxy-1,1-diphosphonate and other known phosphonates
(see, for example, U.S. Patents 3,159,581; 3,213,030; 3,422,021; 3,400,148 and
3,422,137) can also be used.
o Bleach
The detergent compositions herein may optionally contain bleaching agents or
bleaching compositions containing a bleaching agent and one or more bleach
activators. When present, bleaching agents will typically be at levels of from
~5 about 1% to about 30%, more typically from about 5% to about 20%, of the
detergent composition, especially for fabric laundering. If present, the
amount of
bleach activators will typically be from about 0.1 % to about 60%, more
typically
from about 0.5% to about 40% of the bleaching composition comprising the
bleaching agent-plus-bleach activator.
2o The bleaching agents used herein can be any of the bleaching agents useful
for
detergent compositions in textile cleaning, hard surface cleaning, or other
cleaning purposes that are now known or become known. These include oxygen
bleaches as well as other bleaching agents. Perborate bleaches, e.g., sodium
perborate (e.g., mono- or tetra-hydrate) can be used herein.
25 Another category of bleaching agent that can be used without restriction
encompasses percarboxylic acid bleaching agents and salts thereof. Suitable
examples of this class of agents include magnesium monoperoxyphthalate
hexahydrate, the magnesium salt of metachloro perbenzoic acid, 4-nonylamino-
4-oxoperoxybutyric acid and diperoxydodecanedioic acid. Such bleaching
3o agents are disclosed in U.S. Patent 4,483,781, Hartman, issued November 20,
1984, U.S. Patent Application 740,446, Burns et al, filed June 3, 1985,
European
Patent Application 0,133,354, Banks et al, published February 20, 1985, and
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27
U.S. Patent 4,412,934, Chung et al, issued November 1, 1983. Highly preferred
bleaching agents also include 6-nonylamino-6-oxoperoxycaproic acid as
described in U.S. Patent 4,634,551, issued January 6, 1987 to Burns et al.
Peroxygen bleaching agents can also be used. Suitable peroxygen bleaching
compounds include sodium carbonate peroxyhydrate and equivalent
"percarbonate" bleaches, sodium pyrophosphate peroxyhydrate, urea
peroxyhydrate, and sodium peroxide. Persulfate bleach (e.g., OXONE,
manufactured commercially by DuPont) can also be used.
A preferred percarbonate bleach comprises dry particles having an average
o particle size in the range from about 500 micrometers to about 1,000
micrometers, not more than about 10% by weight of said particles being smaller
than about 200 micrometers and not more than about 10% by weight of said
particles being larger than about 1,250 micrometers. Optionally, the
percarbonate can be coated with silicate, borate or water-soluble surfactants.
~5 Percarbonate is available from various commercial sources such as FMC,
Solvay
and Tokai Denka.
Mixtures of bleaching agents can also be used.
Peroxygen bleaching agents, the perborates, the percarbonates, etc., are
preferably combined with bleach activators, which lead to the in situ
production in
2o aqueous solution (i.e., during the washing process) of the peroxy acid
corresponding to the bleach activator. Various nonlimiting examples of
activators
are disclosed in U.S. Patent 4,915,854, issued April 10, 1990 to Mao et al,
and
U.S. Patent 4,412,934. The nonanoyloxybenzene sulfonate (NOBS) and
tetraacetyl ethylene diamine (TAED) activators are typical, and mixtures
thereof
25 can also be used. See also U.S. 4,634,551 for other typical bleaches and
activators useful herein.
Highly preferred amido-derived bleach activators are those of the formulae:
R1 N(R5)C(O)R2C(O)L or R1 C(O)N(R5)R2C(O)L
wherein R1 is an alkyl group containing from about 6 to about 12 carbon atoms,
3o R2 is an alkylene containing from 1 to about 6 carbon atoms, R5 is H or
alkyl,
aryl, or alkaryl containing from about 1 to about 10 carbon atoms, and L is
any
suitable leaving group. A leaving group is any group that is displaced from
the
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28
bleach activator as a consequence of the nucleophilic attack on the bleach
activator by the perhydrolysis anion. A preferred leaving group is phenyl
sulfonate.
Preferred examples of bleach activators of the above formulae include (6-
octanamido-caproyl)oxybenzenesulfonate, (6-nonanamidocaproyl)oxybenzene-
sulfonate, (6-decanamido-caproyl)oxybenzenesulfonate, and mixtures thereof as
described in U.S. Patent 4,634,551, incorporated herein by reference.
Another class of bleach activators comprises the benzoxazin-type activators
disclosed by Hodge et al in U.S. Patent 4,966,723, issued October 30, 1990,
1o incorporated herein by reference. A highly preferred activator of the
benzoxazin-
type is:
O
II
CEO
I
'C
N
Still another class of preferred bleach activators includes the acyl lactam
activators, especially acyl caprolactams and acyl valerolactams of the
formulae:
O O
O C-C H2-C H2 O C-C HZ-C H2
R6-C-N~ ~C H2 R6-C-N~
C H2-C H2 C H2-C H2
wherein R6 is H or an alkyl, aryl, alkoxyaryl, or alkaryl group containing
from 1 to
about 12 carbon atoms. Highly preferred lactam activators include benzoyl
caprolactam, octanoyl caprolactam, 3,5,5-trimethylhexanoyl caprolactam,
nonanoyl caprolactam, decanoyl caprolactam, undecenoyl caprolactam, benzoyl
2o valerolactam, octanoyl valerolactam, decanoyl valerolactam, undecenoyl
valerolactam, nonanoyl valerolactam, 3,5,5-trimethylhexanoyl valerolactam and
mixtures thereof. See also U.S. Patent 4,545,784, issued to Sanderson, October
8, 1985, incorporated herein by reference, which discloses acyl caprolactams,
including benzoyl caprolactam, adsorbed into sodium perborate.
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Bleaching agents other than oxygen bleaching agents are also known in the art
and can be utilized herein. One type of non-oxygen bleaching agent of
particular
interest includes photoactivated bleaching agents such as the sulfonated zinc
and/or aluminum phthalocyanines. See U.S. Patent 4,033,718, issued July 5,
s 1977 to Holcombe et al. If used, detergent compositions will typically
contain
from about 0.025% to about 1.25%, by weight, of such bleaches, especially
sulfonate zinc phthalocyanine.
If desired, the bleaching compounds can be catalyzed by means of a
manganese compound. Such compounds are well known in the art and include,
for example, the manganese-based catalysts disclosed in U.S. Pat. 5,246,621,
U.S. Pat. 5,244,594; U.S. Pat. 5,194,416; U.S. Pat. 5,114,606; and European
Pat. App. Pub. Nos. 549,271 A1, 549,272A1, 544,440A2, and 544,490A1;
Preferred examples of these catalysts include MnlV2(u-O)3(1,4,7-trimethyl-
1,4,7-
triazacyclononane)2(PF6)2, Mnlll2(u-O)1(u-OAc)2(1,4,7-trimethyl-1,4,7-
~5 triazacyclononane)2_(C104)2, MnlV4(u-O)6(1,4,7-triazacyclononane)4(CI04)4,
Mnl l IMnIV4(u-O)1 (u-OAc)2_(1,4,7-trimethyl-1,4,7-triazacyclononane)2(C104)3,
MnIV(1,4,7-trimethyl-1,4,7-triazacyclononane)- (OCH3)3(PF6), and mixtures
thereof. Other metal-based bleach catalysts include those disclosed in U.S.
Pat.
4,430,243 and U.S. Pat. 5,114,611. The use of manganese with various
2o complex ligands to enhance bleaching is also reported in the following
United
States Patents: 4,728,455; 5,284,944; 5,246,612; 5,256,779; 5,280,117;
5,274,147; 5,153,161; and 5,227,084.
As a practical matter, and not by way of limitation, the compositions and
processes herein can be adjusted to provide on the order of at least one part
per
2s ten million of the active bleach catalyst species in the aqueous washing
liquor,
and will preferably provide from about 0.1 ppm to about 700 ppm, more
preferably from about 1 ppm to about 500 ppm, of the catalyst species in the
laundry liquor.
Enzymes
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Enzymes can be included in the formulations herein for a wide variety of
fabric
laundering purposes, inctuding removal of protein-based, carbohydrate-based,
or
triglyceride-based stains, for example, and for the prevention of refugee dye
5 transfer, and for fabric restoration. The enzymes to be incorporated include
proteases, amylases, lipases, cellulases, and peroxidases, as well as mixtures
thereof. Other types of enzymes may also be included. They may be of any
suitable origin, such as vegetable, animal, bacterial, fungal and yeast
origin.
However, their choice is governed by several factors such as pH-activity
and/or
o stability optima, thermostability, stability versus active detergents,
builders and so
on. In this respect bacterial or fungal enzymes are preferred, such as
bacterial
amylases and proteases, and fungal cellulases.
Enzymes are normally incorporated at levels sufficient to provide up to about
5
mg by weight, more typically about 0.01 mg to about 3 mg, of active enzyme per
~ 5 gram of the composition. Stated otherwise, the compositions herein will
typically
comprise from about 0.001 % to about 5%, preferably 0.01 %-1 % by weight of a
commercial enzyme preparation. Protease enzymes are usually present in such
commercial preparations at levels sufficient to provide from 0.005 to 0.1
Anson
units (AU) of activity per gram of composition.
2o Suitable examples of proteases are the subtilisins which are obtained from
particular strains of B. subtilis and B. licheniforms. Another suitable
protease is
obtained from a strain of Bacillus, having maximum activity throughout the pH
range of 8-12, developed and sold by Novo Industries A/S under the registered
trade name ESPERASE. The preparation of this enzyme and analogous
2s enzymes is described in British Patent Specification No. 1,243,784 of Novo.
Proteolytic enzymes suitable for removing protein-based stains that are
commercially available include those sold under the tradenames ALCALASE and
SAVINASE by Novo Industries A/S (Denmark) and MAXATASE by International
Bio-Synthetics, Inc. (The Netherlands). Other proteases include Protease A
(see
3o European Patent Application 130,756, published January 9, 1985) and
Protease
B (see European Patent Application Serial No. 87303761.8, filed April 28,
1987,
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31
and European Patent Application 130,756, Bott et al, published January 9,
1985).
Amylases include, for example, a-amylases described in British Patent
Specification No. 1,296,839 (Novo), RAPIDASE, International Bio-Synthetics,
Inc. and TERMAMYL, Novo Industries.
The cellulase usable in the present invention include both bacterial or fungal
cellulase. Preferably, they will have a pH optimum of between 5 and 9.5.
Suitable cellulases are disclosed in U.S. Patent 4,435,307, Barbesgoard et al,
issued March 6, 1984, which discloses fungal cellulase produced from Humicola
1o insolens and Humicola strain DSM1800 or a cellulase 212-producing fungus
belonging to the genus Aeromonas, and cellulase extracted from the
hepatopancreas of a marine mollusk (Dolabella Auricula Solander). suitable
cellulases are also disclosed in GB-A-2.075.028; GB-A-2.095.275 and DE-OS-
2.247.832. CAREZYME (Novo) is especially useful.
Suitable lipase enzymes for detergent usage include those produced by
microorganisms of the Pseudomonas group, such as Pseudomonas stutzeri
ATCC 19.154, as disclosed in British Patent 1,372,034. See also lipases in
Japanese Patent Application 53,20487, laid open to public inspection on
February 24, 1978. This lipase is available from Amano Pharmaceutical Co.
2o Ltd., Nagoya, Japan, under the trade name Lipase P "Amano," hereinafter
referred to as "Amano-P." Other commercial lipases include Amano-CES,
lipases ex Chromobacter viscosum, e.g. Chromobacter viscosum var. lipolyticum
NRRLB 3673, commercially available from Toyo Jozo Co., Tagata, Japan; and
further Chromobacter viscosum lipases from U.S. Biochemical Corp., U.S.A. and
Disoynth Co., The Netherlands, and lipases ex Pseudomonas gladioli. The
LIPOLASE enzyme derived from Humicola lanuginosa and commercially
available from Novo (see also EPO 341,947) is a preferred lipase for use
herein.
Peroxidase enzymes are used in combination with oxygen sources, e.g.,
percarbonate, perborate, persulfate, hydrogen peroxide, etc. They are used for
"solution bleaching," i.e. to prevent transfer of dyes or pigments removed
from
substrates during wash operations to other substrates in the wash solution.
Peroxidase enzymes are known in the art, and include, for example, horseradish
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32
peroxidase, ligninase, and haloperoxidase such as chloro- and bromo-
peroxidase. Peroxidase-containing detergent compositions are disclosed, for
example, in PCT International Application WO 89/099813, published October 19,
1989, by O. Kirk, assigned to Novo Industries A/S.
s A wide range of enzyme materials and means for their incorporation into
synthetic detergent compositions are also disclosed in U.S. Patent 3,553,139,
issued January 5, 1971 to McCarty et al. Enzymes are further disclosed in U.S.
Patent 4,101,457, Place et al, issued July 18, 1978, and in U.S. Patent
4,507,219, Hughes, issued March 26, 1985, both. Enzyme materials useful for
o liquid detergent formulations, and their incorporation into such
formulations, are
disclosed in U.S. Patent 4,261,868, Hora et al, issued April 14, 1981. Enzymes
for use in detergents can be stabilized by various techniques. Enzyme
stabilization techniques are disclosed and exemplified in U.S. Patent
3,600,319,
issued August 17, 1971 to Gedge, et al, and European Patent Application
15 Publication No. 0 199 405, Application No. 86200586.5, published October
29,
1986, Venegas. Enzyme stabilization systems are also described, for example,
in U.S. Patent 3,519,570.
Other components which are commonly used in detergent compositions and
2o which may be incorporated into detergent tablets include chelating agents,
soil
release agents, soil antiredeposition agents, dispersing agents, suds
suppressors, fabric softeners, dye transfer inhibition agents and perfumes.
The compounds disclosed above for a product are advantageously packed in a
2s packaging system.
A packaging system may be formed from a sheet of flexible material. Materials
suitable for use as a flexible sheet include mono-layer, co-extruded or
laminated
films. Such films may comprise various components, such as poly-ethylene, poly-
propylene, poly-styrene, poly-ethylene-terephtalate. Preferably, the packaging
3o system is composed of a poly-ethylene and bi-oriented-poly-propylene co-
extruded film with an MVTR of less than 5 g/day/m2. The MVTR of the packaging
system is preferably of less than 10 g/day/m2, more preferably of less than 5
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33
g/day/m2. The film (2) may have various thicknesses. The thickness should
typically be between 10 and 150 Vim, preferably between 15 and 120 Vim, more
preferably between 20 and 100 Vim, even more preferably between 25 and 80
~m and most preferably between 30 and 40 p.m.
A packaging material preferably comprises a barrier layer typically found with
packaging materials having a low oxygen transmission rate, typically of less
than
300 cm3/m2/day, preferably of less than 150 cm3/m2/day, more preferably of
less
than 100 cm3/m2/day, even more preferably of less than 50 cm3/m2/day and most
preferably of less than 10 cm3/m2/day. Typical materials having such barrier
o properties include bi oriented polypropylene, poly ethylene terephthalate,
Nylon,
polyethylene vinyl alcohol) , or laminated materials comprising one of these,
as
well as SiOx (Silicium oxydes), or metallic foils such as aluminium foils for
example. Such packaging material may have a beneficial influence on the
stability of the product during storage for example.
~5 Among the packing method used are typically the wrapping methods disclosed
in
W092/20593, including flow wrapping or over wrapping. When using such
processes, a longitudinal seal is provided, which may be a fin seal or an
overlapping seal, after which a first end of the packaging system is closed
with a
first end seal, followed by closure of the second end with a second end seal.
The
2o packaging system may comprise re-closing means as described in W092/20593.
In particular, using a twist, a cold seal or an adhesive is particularly
suited.
Indeed, a band of cold seal or a band of adhesive may be applied to the
surface
of the packaging system at a position adjacent to the second end of the
packaging system, so that this band may provide both the initial seal and re-
25 closure of the packaging system. In such a case the adhesive or cold seal
band
may correspond to a region having a cohesive surface, i.e. a surface which
will
adhere only to another cohesive surface. Such re-closing means may also
comprise spacers which will prevent unwanted adhesion. Such spacers are
described in WO 95/13225, published on the 18t" of May 1995. There may also
3o be a plurality of spacers and a plurality of strips of adhesive material.
The main
requirement is that the communication between the exterior and the interior of
the package should be minimal, even after first opening of the packaging
system.
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34
A cold seal may be used, and in particular a grid of cold seal, whereby the
cold
seal is adapted so as to facilitate opening of the packaging system.
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EXAMPLES
Example 1
5
i) 25 Kg of a detergent base powder of composition A was prepared as follows:
all the particulate material of base composition were mixed together in a
mixing drum to form a homogenous particulate mixture. During this mixing,
the spray-ons were carried out. After preparation the matrix was kept in a
seated plastic bag in a storage room set at a temperature of 23°C for
24
hours.
ii) Tablets were then made the following way: 50g of the matrix was introduced
into a mould of circular shape with a diameter of 5.5 cm, and compressed to
give a tablet tensile strength (or diametrical fracture stress) of 10kPa. The
15 temperature of the matrix during tabletting ranged between 23 and
27°C.
iii) The tablets were then dipped in a bath comprising 90 parts of sebacic
acid
and 10 parts per weight of Nymcel-ZSB16T'" by Metsa Serla at 140 °C.
The
time the tablet was dipped in the heated bath was adjusted to allow
application of 4g of the bath mixture. The tablet was then left to cool at
2o ambient temperature of 25°C for 24 hours. The tensile strength of
the coated
tablet was increased to a tensile strength of 30 kPa.
iv) The level of residue in the drawer dispenser of a washing machine was
assessed by the following "Tablet dispensing test": two tablets are placed
into
the dispensing drawer of a Bauknecht WA9850 washing machine. the water
25 supply to the washing machine is set to a temperature of 8°C and to
a
hardness of 21 grains per gallon, the flow rate being of 4 litres per minute.
The level of tablet residues left in the dispenser is checked after switching
on
the water flow for 78 seconds. The dispensing percentage residue is
determined as follows:
30 %dispensing = (residue weight) x 100 / (original weight of both tablets).
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36
Composition
A
(% by weight)
Anionic agglomerates 1 21.5
Anionic agglomerates 2 13.0
Cationic agglomerates 5.5
Layered silicate 10.8
Sodium percarbonate 14.2
Bleach activator agglomerates 5.5
Sodium carbonate 10.98
EDDS/Sulphate particle 0.5
Tetrasodium salt of Hydroxyethane 0.8
Diphosphonic acid
Soil Release Polymer 0.3
Fluorescer 0.2
Zinc Phthalocyanine sulphonate 0.02
Soap powder 1.4
Suds suppressor 1,g
Citric acid 7,1
Protease p,g
Lipase 0.3 -
Cellulase 0.2
Amylase 1.0
Binder spray-on system 4
Anionic agglomerates 1 comprise of 40% anionic surfactant, 27% zeolite and
33% carbonate
Anionic agglomerates 2 comprise of 40% anionic surfactant, 28% zeolite and
32% carbonate
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37
Cationic agglomerates comprise of 20% cationic surfactant, 56% zeolite and 24%
sulphate
Layered silicate comprises of 95% SKS 6 and 5% silicate
Bleach activator agglomerates comprise of 81 % TAED, 17% acrylic/maleic
copolymer (acid form) and 2% water.
Ethylene diamine N,N-disuccinic acid sodium salt/Sulphate particle comprise of
58% of Ethylene diamine N,N-disuccinic acid sodium salt, 23% of sulphate and
19% water.
Zinc phthalocyanine sulphonate encapsulates are 10% active.
Suds suppressor comprises of 11.5% silicone oil (ex Dow Corning); 59% of
zeolite and 29.5% of water.
Binder spray-on system comprises 25% of Lutensit K-HD 96 and
75% by weight of PEG (Poly Ethylene Glycol).
All % above for composition being by weight.
Example 2
i) 25 Kg of a detergent base powder of composition A was prepared as follows:
2o all the particulate material of base composition were mixed together in a
mixing drum to form a homogenous particulate mixture. During this mixing,
the spray-ons were carried out. After preparation the matrix was kept in a
sealed plastic bag in a storage room set at a temperature of 10°C for
24
hours.
ii) Tablets were then made the following way: 50g of the matrix was introduced
into a mould of circular shape with a diameter of 5.5 cm, and compressed to
give a tablet tensile strength (or diametrical fracture stress) of 10kPa. The
temperature of the matrix during tabletting ranged between 10 and 20°C.
iii) The tablets were then dipped in a bath comprising 90 parts of sebacic
acid
3o and 10 parts per weight of Nymcel-ZSB16T"" by Metsa Serla at 140 °C.
The
time the tablet was dipped in the heated bath was adjusted to allow
application of 4g of the bath mixture. The tablet was then left to cool at
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38
ambient temperature of 25°C for 24 hours. The tensile strength of the
coated
tablet was increased to a tensile strength of 30 kPa.
iv) The level of residue in the drawer dispenser of a washing machine was
assessed by the following "Tablet dispensing test": two tablets are placed
into
the dispensing drawer of a Bauknecht WA9850 washing machine. the water
supply to the washing machine is set to a temperature of 8°C and to a
hardness of 21 grains per gallon, the flow rate being of 4 litres per minute.
The level of tablet residues left in the dispenser is checked after switching
on
the water flow for 78 seconds. The dispensing percentage residue is
o determined as follows:
%dispensing = (residue weight) x 100 / (original weight of both tablets).
Results:
%dispensing for example 1 tablets was found to be 50%, whereas %dispensing
~5 for example 2 tablets was found to be 8%.
