Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR PRODUCING A POWDER FROM A PACKAGED TABLET
The present invention relates to a process for producing a powder from
packaged detergent tablets, especially those adapted for use in washing.
Detergent tablets are widely used in different types of washing or cleaning
applications. In auto dish washing application, such tablets are produced from
an original highly compressed powder having a given chemical composition,
whereby the highly compressed tablet is not sensitive to mechanical stress
because it is solid, and whereby the tablet readily dissolves in the dish
washing
machine for producing the aqueous solution comprising surfactants. In the
production process of such tablets, it may occur that a low proportion of the
tablet produced are not suitable for use, for example because of a non
adequate
chemical composition, or because of breakage on the line. In such a case, the
tablets which are not suitable for use are typically recycled by crushing and
dissolving the not suitable tablets to form a solution, so that a powder may
be
obtained from this solution, this powder being added in small proportion to
the
original powder to be compressed again for making tablets suitable for use.
This process is further complicated in cases of use of packaged tablets,
whereby such tablets may be used also for producing powder, and whereby it
should be avoided that the powder obtained contains pieces of the package.
The aim is than to selectively separate the package from its content, i.e. the
tablet, to avoid contamination of the obtained powder by remains of package.
The present invention concerns a process for producing a powder from a
packaged tablet, the package comprising plastic materials.
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Among the advantages of such a process is that it can be used for reducing
waste in the environment while maintaining a satisfactory quality for the
tablets
to use.
While having these and other advantages, existing processes for producing a
powder from a tablet, particularly the processes used for recycling auto dish
washing tablets, have disadvantages. For example, such a process does not
apply to the separation of the package from the tablet in cases where the
tablet
is packaged prior to being processed.
The invention seeks to provide a process of the above mentioned kind which
allows to obtain a recycled powder which is not contaminated by packaging
residues.
Summary of the Invention
In accordance with the invention, this object is accomplished in a process of
the
above kind in that it comprises a first step of submitting the packaged tablet
to
mechanical degradation with first mechanical degradation means, a second step
of sifting with first sifting means to obtain an intermediate material, a
third step
of submitting the intermediate material to mechanical degradation with second
mechanical degradation means, and a fourth step of sifting with second sifting
means to obtain the powder, whereby the powder obtained comprises less than
0.05% per weight of plastic material.
A process in accordance with the invention has a number of advantages. Since
the recycling of the tablet is made using mechanical agitation and sifting,
the
recycled powder can be obtain without passing by a dissolution step, although
it
could be preferred to add such a step in particular conditions. Furthermore,
the
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combination of the four steps allows to minimise the amount of plastic
material
contained in the obtained powder.
Detailed Description of the Invention
The invention relates to a process for producing a powder from a packaged
tablet. In a preferred embodiment according to the invention the tablet is
having
a tensile strength of at least 5 kPa, preferably the tensile strength is of at
least
kPa, more preferably of at least 15 kPa and even more preferably of at least
kPa, so that the tablet is sufficiently mechanically resistant while
dissolving
readily. The tablet also preferably comprises surfactants, more preferably at
least 2 % by weight of surfactants. In a preferred embodiment according to the
invention, the tablet comprises at least 10 % by weight of surfactants, more
preferably at least 15 % and most preferably at least 20 %. Indeed, the
invention
more particularly relates to laundry tablets, laundry tablets having a
particularly
high level of surfactant. The process according to the invention comprises a
first
step, whereby the tablet is submitted to mechanical degradation. Mechanical
degradation may be obtained via different means, the preferred means for
mechanical degradation being provided by centrifugation, preferably by use of
a centrifugal sifter, in particular a KEK centrifugal sifter from KEMUTEC,
preferably a K650. The second step of the process consists in sifting to
obtain
the intermediate material. Indeed, after having been submitted to mechanical
degradation, the packaged tablet is not a solid block but consists in a
plurality of
grains or package pieces. Sifting allows to select a part of these grains or
package pieces. In a preferred embodiment according to the invention, sifting
in
the second step is obtained by a mesh having a plurality of 8 mm diameter
apertures. Preferably, the mesh size is comprised between 2 and 15 mm, more
preferably between 5 and 12 mm, and most preferably between 6 and 10 mm.
The rest of the grains or package pieces which is does not sift through is
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evacuated and is not comprised in the intermediate material. Typically, the
rest
of the grains or package pieces which are not submitted to the second step
represents less than 1 % per weight of the whole grains or package pieces.
Most
of this rest is formed from plastic materials. This rest is preferably not re-
inserted directly at the start of the process according to the invention, but
may
be submitted to an extra treatment. According to the invention, the
intermediate
material is thereafter submitted to a third step similar to the first step,
and to a
fourth step similar to the second step. Preferred for the fourth step is use
of a
nylon sieve having apertures having a diameter comprised between 2.4 and 3.5
mm. Preferably, the mesh size or the diameter of the apertures is comprised
between 1 and 6 mm, more preferably between 1.5 and 5 mm, and most
preferably between 2 and 4 mm. Similarly, a part of the intermediate material
is
sifted, the other part being rejected. According to he invention, it was found
that
use of such a process allows that the obtained powder comprises less than 0.05
°r6 per weight of plastic material, preferably less than 0.03 % per
weight, more
preferably less than 0.02 %, and most preferably less than 0.01 %.
In a preferred embodiment according to the invention, the intermediate
material
is such that it comprises less than 5% per weight of particles passing through
a
150 micrometer sieve, the obtained powder being such that it comprises less
than 6% per weight of particles passing through a 150 micrometer sieve. In a
preferred embodiment, the obtained powder is such that it comprises less than
5°r6 per weight of particles passing through the 150 micrometer sieve.
It should
be noted that the 150 micrometer sieve referred to is normally different from
the
sieving means used in the second step according to the invention, and that it
is
mentioned in the purpose of providing means for analysing the granular
structure of the obtained powder or intermediate material. The minimisation of
the level of one particles allows to improve the sanitary and environmental
characteristics of the obtained powder. This more particularly applies to a
tablet
comprising enzymes, whereby it is preferred that the enzymes components of
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the tablet are not broken up during the process. Breaking up of percarbonate
components should also be avoided, as the stability of the finished product
could be affected. Indeed, typically tablets according to the invention would
be
tablets which require being packed in order to stabilise their chemical
evolution
thanks to specific characteristics of the package, as described in the EP
application of the applicant number 97202674.4. Indeed, in a preferred
embodiment, the invention relates to a tablet comprising percarbonates.
Furthermore, limitation of the level of fine particles allows to obtain a
better
dissolution for a tablet in a wash environment if a tablet is made which
comprises the obtained powder.
The invention particularly applies to re-blending of non-satisfactory tablets
to an
original powder, whereby the powder obtained is added to an original powder to
form a mixture, the added powder constituting at least 1 % and up to 20 % per
weight of the mixture, the mixture being compressed to form a tablet.
Preferably,
in such a case, the powder obtained comprises a percentage per weight of
particles passing through a 150 micrometer sieve which is less than twice the
percentage per weight of particles passing through a 150 micrometer sieve and
comprised in the original powder. Indeed, the more the obtained powder has a
granular structure close to the original powder, in particular regarding fine
particles, the more reliable will the re-blending process be. In such a case,
the
original tablet which is submitted to the process according to the invention
is
itself typically made by compressing the original powder, and by adding or not
a
coating. Typically, the invention relates to tablets having a tensile strength
of
less than 700 kPa. More preferred are tablets having a tensile strength of
less
than 150 kPa, even more preferred tablets having a tensile strength of less
than
100 kPa, most preferred tablets having a tensile strength of less than 50 kPa
or
even less than 30 kPa. Indeed, the tablets according to the invention should
readily dissolve in a washing environment, so the tablets should not be
excessively compressed. It should be noted that the process according to the
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invention could also be considered for producing a powder from a tablet
typically used for auto dish washing, although the dissolution characteristics
are
not so stringent as for laundry tablets, so that the invention is even more
advantageous when applied to laundry tablets.
When applied industrially, the process according to the invention allows to
treat
a plurality of tablets at a rate of at least 100 and up to 300 kilograms per
hour
and per mechanical degradation and sifting means.
Tablet package
In a preferred embodiment, the tablets of the invention comprise a bleaching
agent. Typically, the bleaching agent will be an inorganic per-hydrate bleach.
Such bleaching agents comprise sodium per-borate, which may be in the form of
the mono-hydrate or of the tetra-hydrate. Other per-hydrate salts can also be
used, such as sodium per-carbonate. Such components are a useful source of
carbonate ions for detergency purposes. However, such per-carbonates are
particularly unstable in moisture and also release gas, such as oxygen.
Therefore, packing should to be suitable so as to take account of these two
features.
Because a bleaching agent is decomposing in moisture and consequently
loosing its bleaching properties, it is important to protect the tablets from
ingress
of external moisture. Ideally, this could be achieved by packing each tablet
in a
separate package to open just prior to use, the package being completely water-
impermeable. In order to achieve efficient protection of the tablets, it is
preferred
that the packaging system has a limited Moisture Vapour Transfer Rate (MVTR).
The MVTR of the packaging system is measured at 40°C and 75% eRH,
which
corresponds to a environment particularly damaging for the tablets. It was
found
that the MVTR should not exceed 20 glm2lday in order to fulfil the
requirements
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of the packaging system, corresponding to a protection effective for a six
month
period in real conditions.
The packaging system should also take account of the fact that gas may be
released by its content. This may be achieved by a micro-hole which is made in
the packaging system. A micro-hole would act as a communication between the
inside of the packaging system and the outside of the packaging system. The
main characteristics of a micro-hole is that the communication it provided is
pressure sensitive. Indeed, if the pressure inside of the packaging system and
the pressure outside of the packaging system are in equilibrium, the micro-
hole
will have a negligible influence on the transmission characteristics of the
packaging system because of the resilience of the material. Indeed, no
significant amount of the material is taken away when making a micro-hole, so
that it will be substantially closed in the absence of a pressure gradient
between
the inside and the outside of the bag. However, once a pressure gradient
appears, the packaging system will be slightly distorted, so that the micro-
hole
will open itself and allow significant communication between the outside and
the
inside of the package in order to minimise the pressure gradient. This means
that in case of release of a gas, the inner pressure will increase, thus
creating a
pressure gradient which will open the micro-hole, through which the excess of
gas will be evacuated. The micro-hole is acting as a discharge orifice without
letting moisture enter the bag in a significant manner as the external
pressure is
normally always lower or equal to the inner pressure. This mechanism can be
tuned by using various sizes for the micro-holes as well as by choosing the
number of micro-holes needed per packaging system, taking account of the
composition and of the quantity of the content of the packaging system, and
taking also account of the MVTR of the packaging system. Indeed, a non zero
MVTR will allow some communication between the inside and the outside of the
bag.
The packaging system of the preferred embodiment is originally composed of a
sheet of material (2) having the required MVTR. Materials suitable for this
use
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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. in a most preferred embodiment of the invention, the
packaging system is composed of a poly-ethylene and bi-oriented-poly-
propylene co-extruded film with an MVTR of less than 1 g/day/m2. The MVTR of
the packaging system is preferably of less than 10 g/daylm2, more preferably
of
less than 5 g/day/m2, even more preferably of less than 1 g/daylm2 and most
preferably of less than 0.5 g/daylm2. 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 um.
Highly soluble Compounds
The tablet according tot he invention may further comprise a highly soluble
compound to further facilitate dissolution. Such a compound could be formed
from a mixture or from a single compound. A highly soluble compound is defined
as follow:
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 deionised water is introduced into the Sotax beaker.
3- 10 s after the water introduction, the conductivity of the solution is
measured,
using a conductivity meter.
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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.
The specific compound is highly sofuble 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
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
sulphonate or Sodium toluene sulphonate.
Cohesive Effect
The tablet according to the invention could also comprise a compound or a
mixture of compounds having a cohesive effect, so that the tablet could be
mechanically even stronger at constant compression force. The Cohesive Effect
on the particulate material of a detergent matrix is characterised by the
force
required to break a tablet based on the examined detergent matrix pressed
under controlled compression conditions. For a given compression force, a high
tablet 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 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.
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The cohesive effect induced by the highly soluble compound is measured
according to the invention by comparing the tablet strength of the original
base
powder without highly soluble compound with the tablet strength of a powder
mix which comprises 97 parts of the original base powder and 3 parts of the
highly soluble compound. The highly soluble compound is 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 highly soluble 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 preferably 100%) by means of the presence of 3% of
the highly soluble compound having a cohesive effect in the base particulate
material.
It should be noted that in particular when integrating a highly soluble
compound
having a cohesive effect on a tablet formed by compressing a particulate
material comprising a surfactant, the dissolution of the tablet in an aqueous
solution was significantly increased. In a preferred embodiment, at least 1 %
per
weight of the tablet is formed from the highly soluble compound, more
preferably
at least 2%, even more preferably at lest 3% and most preferably at least 5%
per weight of the tablet being formed from the highly soluble compound having
a
cohesive effect on the particulate material.
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
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traditional tablets. Typically, the 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 30
kPa; and a tensile strength 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 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 most
preferably
of less than 30 kPa.
This allows to produce tablets which have a solidity and mechanical resistance
comparable to the solidity or mechanical resistance of traditional tablets
while
having a less compact tablet thus dissolving more readily. Furthermore, as the
compound is highly soluble, the dissolution of the tablet is further
facilitated,
resulting in a synergy leading to facilitated dissolution for a tablet
according to
the invention.
Tablet Manufacture
The invention allows to obtain a less compact and less dense tablet at
constant
compacting force when compared to a traditional detergent tablet.
Detergent tablets of the present invention 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 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
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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
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 the tablet of this invention can be
made
by any particulation or granulation process. An example of such a process is
spray drying (in a co-current or counter current spray drying tower) which
typically gives low bulk densities 600g/l 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 andlor Lodige~ KM mixers). Other suitable processes
include fluid bed 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
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
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 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.
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The tablets may be manufactured by using any compacting process, such as
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
diameter (or width) of the tablets is preferably greater than 1:3, more
preferably
greater than 1:2. The compaction pressure used for preparing these tablets
need not exceed 100000 kNlmz, preferably not exceed 30000 kNlm2, more
preferably not exceed 5000 kNlm2, 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 glcc, and
more
preferably of less than 1.5 g/cc.
Hydrotrope compound
In a preferred embodiment of the invention, the tablet also comprises a
hydrotrope compound which is further favouring dissolution of the tablet in an
aqueous solution, a specific compound being defined as being hydrotrope as
follows (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
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
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bottom of the beaker, the mixer being set at a rotation speed of 200 rounds
per
minute.
3. The specific compound is hydrotrope if 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
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:
1. Nonionic hydrotrope with the following structure:
R - O - (CH2CH20)x( CFI -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
derivatives, naphthoic acid and various hydroaromatic acids. Examples of these
are sodium, potassium and ammonium benzene sulfonate salts derived from
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
glycerin, polyglycerol esters. Preferred alkoxylated glycerines have the
following
structure:
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R
~H=-a~.cHicH-o-~"H
R
CHr.O(~H~li-O~~"H
I R
CHrO(-CH~CH-C'~,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
CZHs
Preferred alkoxylated glycerides have the following struture
HiC',-R,
Ra Ra
H=C-C~(CH~H-O)-H
where R1 and R2 are each C~COO or -(CH2CHR3-O),-H where R3 = H, CH3 or
CZHS 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 R2
where E is a hydrophilic functional group,
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, for example. Such a compound could be formed from a mixture or
from a single compound.
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Coating
Solidity of the tablet according to the invention may be further improved by
making a coated tablet, the coating covering a non-coated tablet according to
the invention, thereby further improving the mechanical characteristics of the
tablet while maintaining or further improving dissolution.
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 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 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".
Suitable coating materials are 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 acid, undecanedioic acid, dodecanedioic acid, tridecanedioic
acid
and mixtures thereof.
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.
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In a), the coating material is applied at a temperature above its melting
point,
and 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
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. Clearly substantially insoluble materials having a melting point
below
40 °C are 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. Preferably, the materials melt in the range from 60 °C to 160
°C, more
preferably from 70 °C to 120 °C.
By "melting point" is meant the temperature at which the material when heated
slowly in, for example, a capillary tube becomes a clear liquid.
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.
The tablet coatings of the present invention are very hard and provide extra
strength to the tablet.
In a preferred embodiment of the present invention the fracture of the coating
in
the wash is improved by adding a disintegrant in the coating. This
disintegrant
will swell once in contact with water and break the 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, modified 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
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alginate, silicone dioxide, clay, polyvinylpyrrolidone, soy polysacharides,
ion
exchange resins and mixtures thereof.
Tensile Strength
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
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, and
is
determined by the following equation
_ 2F
~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, and t the thickness 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
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.
Typically,
the tablet according to the invention will have a tensile strength in a
direction
normal to the main axis of more than 5kPa, preferably of more than 10kPa, more
preferably, in particular for use in laundry applications, of more than 15kPa,
even more preferably of more than 20 kPa. The tablet according to that
invention should also dissolve readily so that it has a tensile strength
preferably
of less than 75 kPa, and more preferably of less than 50 kPa.
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
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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.
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 percentage residue is determined as follows:
dispensing = residue weight x 100 I 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
ugrain 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
In another preferred embodiment of the present invention the tablets further
comprises an effervescent which is a compound further favouring dissolution of
the tablet in an aqueous solution.
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. C6Hg07 + 3NaHCOg ~ NagC6H507 + 3C02'~ + 3H20
Further examples of acid and carbonate sources and other effervescent systems
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 % 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
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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Detersive surfactants
Surfactant are comprised in the tablet according to the invention. 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 C1 ~ _C1 g alkyl benzene
sulfonates ("LAS") and primary, branched-chain and random C1p_C20 alkyl
sulfates ("AS"), the C1p_C18 secondary (2,3) alkyl sulfates of the formula
CH3(CH2)x(CHOSOg_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_C18 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_C~g alkyl ethoxylates ("AE") including
the so-called narrow peaked alkyl ethoxylates and C6-C12 alkyl phenol
alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C12_C18
betaines and sulfobetaines ("sultaines"), C10_C1g amine oxides, and the like,
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-C18 N-methylglucamides. See WO 9,206,154. Other sugar-derived
surfactants include the N-alkoxy polyhydroxy fatty acid amides, such as C10-
C1 g N-(3-methoxypropyl) glucamide. The N-propyl through N-hexyl C12-C18
glucamides can be used for low sudsing. C1p-C20 conventional soaps may
also be used. If high sudsing is desired, the branched-chain C10-C16 soaps
may be used. Mixtures of anionic and nonionic surfactants are especially
useful. Other conventional useful surfactants are listed in standard texts. In
a
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preferred 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 to the particles forming the tablet in
order
to further facilitate dissolution. Such compounds are further favouring
dissolution of the tablet in an aqueous solution
If non gelling binders are used, suitable non-gelling binders include
synthetic
organic polymers such as polyethylene glycols, poiyvinylpyrrolidones,
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
triamines, or others such as pentaamines, ethoxylated polyethylene amines,
malefic acrylic polymers.
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,
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23
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 is a non laundry active material below 2% by weight of the tablet.
It is preferred that gelling binders, such as nonionic surfactants are avoided
in
their liquid or molten form. Nonionic surtactants 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 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, 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
so-called "underbuilt" situation that may occur with zeolite or layered
silicate
builders.
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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
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. 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 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
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:
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)12]~xHZO
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.
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 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. Patent 3,128,287, issued April 7, 1964, and Lamberti et al, U.S.
Patent 3,635,830, issued January 18, 1972. See also "TMSITDS" 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 alicyclic
compounds, such as those described in U.S. Patents 3,923,679; 3,835,163;
4,158,635; 4,120,874 and 4,102,903.
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Other useful detergency builders include the ether hydroxypolycarboxylates,
copolymers of malefic anhydride with ethylene or vinyl methyl ether, 1, 3, 5-
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, oxy-
disuccinic 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
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-
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, 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,
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-C1 g monocarboxylic acids, can also be incorporated
into
the compositions alone, or in combination with the aforesaid builders,
especially
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citrate and/or the succinate builders, to provide additional builder activity.
Such
use of fatty acids will generally result in a diminution of sudsing, which
should
be taken into account by the formulator.
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.
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
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.
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.
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 monoperoxyphthaiate
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hexahydrate, the magnesium salt of metachloro perbenzoic acid, 4-nonylamino-
4-oxoperoxybutyric acid and diperoxydodecanedioic acid. Such bleaching
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 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
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.
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 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
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thereof 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,
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
bleach activator as a consequence of the nucleophiiic 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-caproyf)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,
incorporated herein by reference. A highly preferred activator of the
benzoxazin-type is:
O
II
CEO
of
..~ o
N
Still another class of preferred bleach activators includes the acyl lactam
activators, especially acyl caprolactams and acyl valerolactams of the
formulae:
O 0
0 C-CH2-CH2 0 C-CH2-CH2
R6-C-N \C H Rs-C-N
wCH - H
CH2-CH2 2 2
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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
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.
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 andlor aluminum phthalocyanines. See U.S. Patent 4,033,718,
issued July 5, 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-
triazacyclononane)2_(C104)2, MnlV4(u-O)6(1,4,7-triazacyclononane)4(C104)4,
MnIIIMnIV4(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
complex ligands to enhance bleaching is also reported in the following United
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31
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 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
Enzymes can be included in the formulations herein for a wide variety of
fabric
laundering purposes, including removal of protein-based, carbohydrate-based,
or triglyceride-based stains, for example, and for the prevention of refugee
dye
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
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
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.
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32
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
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 European Patent Application 130,756, published January 9,
7985) and Protease B (see European Patent Application Serial No. 87303761.8,
filed April 28, 1987, 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
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
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33
February 24, 1978. This lipase is available from Amano Pharmaceutical Co.
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
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.
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
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
Publication No. 0 199 405, Application No. 86200586.5, published October 29,
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34
198fi, 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
which may be incorporated into the detergent tablets of the present invention
include chelating agents, soil release agents, soil antiredeposition agents,
dispersing agents, brighteners, suds suppressors, fabric softeners, dye
transfer
inhibition agents and perfumes.
EXAMPLES
The following process took place according to the invention:
Tablets are flow wrapped two by two in a film using a film wrapping process.
Indeed, in a preferred embodiment according to the invention, the packaged
tablet comprises at least 1.5 % per weight of plastic material, more
preferably at
least 2 % per weight, and less than 3 % per weight of plastic material,
preferably
less than 2.5 % per weight. These flow-wrapped tablets are fed via a first
sifter
inlet into a first feed auger at a rate of 200+I- 100kg/h. The first feed
auger
conveys the packaged tablets into a cylindrical sifting chamber where the
packaged tablets are picked up by a rotating paddle assembly and thrown
centrifugally against the first sieve screen having apertures of a size of 8
mm.
Blades on the paddle assembly are set in a helix configuration to carry the
material along the entire length of the first sieve screen. The product below
the
sieve size which passed through the screen is collected at a main sifter
outlet.
This is the intermediate material. To ensure separation of powder from
plastic,
the intermediate material from the first sifter is fed to a second sifter
similar to
the first one but with a nylon sieve of 2.4-3.5mm, here again a second feed
auger conveying the product into the second cylindrical sifting chamber where
it
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is picked up by a rotating paddle assembly and thrown centrifugally against
the
second sieve screen. Blades on the paddle assembly carry the material along
the entire length of the sieve screen. The product below the sieve size which
passed through the screen is collected at the main sifter outlet. This is the
obtained powder. The rest of the flow-wrapped and oversize of the powder is
conveyed to the end of the sifting chamber and is discharged through a
separate smaller outlet.
Equipment specifications : Both sifter casings are fabricated from carbon
steel
epoxy resin coated. Motor, couplings and bearings are located outside the
process area so do not come into contact with the product. Drive shafts made
with stainless steel carries both the feeder auger and the paddle assembly.
The
design of the sieve screen frame for the first sifter is a 3 ring 3-steel
strut all
welded or bolted construction in carbon steel or stainless steel whilst for
the
second sifter is a full length sieve screen of nylon.
Product specifications : We have used the centrifugal sifter for flow-wrapped
rectangular tablets. Dimensions of tablets are
weight : 53 +I- 2 g diameter : 54 mm, height 21.5 +I- 0.25 mm strength of the
tablets : 35 +/- 4 Kpa
Chemical composition A of the tablets without coating is as follows:
Composition
A
(% per weight}
ionic Agglomerates 1 21.45
nionic Agglomerates 2 13.00
Cationic Agglomerate 5.45
Layered Silicate 10.8
Sodium percarbonate 14.19
Bleach activator agglomerates 5.49
Sodium carbonate 13.82
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EDDS/Sulphate particle 0.47
etrasodium salt of Hydroxyethane Diphosphonic0.73
acid
oil Release Polymer 0.33
Fluorescer 0.18
inc Phthalocyanide sulphonate encapsulate0.025
Soap powder 1.40
uds Suppressor 1.87
Citric acid 7.10
Protease 0.79
Lipase p.28
Cellulase . 0.22
mylase 1.08
Binder Spray-on-system 1.325
OTAL 100.00
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.
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 saIt/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.
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Binder spray-on system comprises of 50% Lutensit K-HD 96 and 50% PEG
(polyethylene glycol).
Production of the tablet:
The detergent base powder of composition A (see table above) was
prepared as follows: all the spray-ons were carried out for the particulate
material of base composition A in a spraying drum, before being mixed
together in a mixing drum to form a homogenous particulate mixture.
ii) Tablets were then made the following way: 53 g of the mixture was
introduced into a mould of the appropriate circular or rectangular shape and
compressed.
iii) Tablets were dipped in a bath comprising 80 parts of sebacic acid mixed
with
20 parts of Nymcel zsb16. The time the tablet was dipped in the heated bath
was adjusted to allow application of 3g of the described mixture on it. The
tablet
was then left to cool at room temperature of 25C for 24 hours.
The obtained powder and the intermediate material had a granular structure
comparing to the granular structure of the original matrix A as follows:
Mesh Size Original Mixture Intermediate Obtained powder
(p.m) (% per weight material (% per weight
deposited on the (% per weight deposited on the
respective sieve)deposited on respective sieve)
the
respective sieve)
1180 9.66 24.5 8.9
850 24.59 32.7 20.9
450 64.65 76.9 70.3
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250 91.29 91.3 88:1
150 96.64 96 95
through 3.36 4 5
150
Mean 500 ~m 638 ~m 541 ~m
Particle
Size
The above table should be read as follows:
The obtained powder has 8.9% per weight of material which stays on the 1180
micrometer sieve, which compares to 9.66% per weight of the original mixture
obtained after step i) above which stays on the 1180 micrometer sieve. The 6
sieves {1180, 850, 450, 250 and 150 micrometer) are placed the one onto the
other, the larger mesh size on top and the smaller mesh size on the bottom, so
that the granular structure can be analysed. The percentage per weight of
particles which go through all sieves, i.e. the "through 150" represents the
percentage per weight of fine particles. The table above also indicates the
mean
particle size for the material considered.
It should be noted that the level of fine particles passing through the 150
micrometer sieve is below 6% per weight for the obtained powder, and is less
than twice the percentage per weight of particles passing through the 150
micrometer sieve and comprised in the original powder or original mixture. It
should be noted that the tablet submitted to the process according to the
invention and described in this example has a coating, the obtained powder
compared to the original powder or mixture used for making the tablet without
coating. The process also applies to non coated tablets.
It should also be noted that the 6 sieves above are introduced to define the
level
of fine particles obtained in the obtained recycled powder, and are usually
different from the means used in the second or fourth step of sifting.
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Less than 0.01 % per weight of plastic film residues were found at the end of
the
second sifter in the obtained powder.
