Note: Descriptions are shown in the official language in which they were submitted.
CA 02300016 2000-02-25
1
Storage-stable Detergent Tablets
This invention relates generally to compact shaped bodies having
detersive properties. Detersive shaped bodies include, for example,
laundry detergent tablets, tablets for dishwashing machines or for cleaning
hard surfaces, bleach tablets for use in washing or dishwashing machines,
water softening tablets or stain remover tablets. More particularly, the
present invention relates to detergent tablets which are used for cleaning
tableware in domestic dishwashing machines and which are often referred
to in short as detergent tablets.
The composition of the tablets varies according to their intended
use. Thus, laundry detergent tablets contain large quantities of surfactants
whereas dishwasher tablets contain only small quantities of surfactants and
bleach tablets are often completely free from surfactants. Ingredients
which are used both in laundry detergent tablets and in dishwasher tablets
and bleach tablets are, in particular, builders, bleaching agents and
enzymes; bleach tablets may even be free from enzymes.
Both where bleaching agents and where enzymes are used in
detergent tablets, the problem of stability over prolonged periods exists.
Thus, the tablets are expected to develop a high performance level not only
immediately after their production, but also after storage, transportation and
possible residence times at the end user. This problem is aggravated by
the close contact between the ingredients mentioned in tablets and other
ingredients which affect their stability. Incompatibility between ingredients
is more noticeable in tablets than, for example, in powders. Such incom-
patibility exists, for example, between oxidation-sensitive ingredients (dyes,
enzymes etc.) and bleaching agents, between bleaching agents and bleach
activators, etc. Accordingly, one of the problems addressed by the present
invention was to increase the storage stability of bleaching agents and
enzymes in detergent tablets.
CA 02300016 2000-02-25
2
There is very little prior art literature on improvements in the stability
of enzymes in detergent tablets whereas the loss of active oxygen from
bleach-containing tablets is the subject of numerous proposed solutions.
Thus, European patent application EP 481 792 (Unilever) describes
detergent tablets containing .a persalt and a bleach activator, the bleach
activator having to have a certain pseudo-first-arrangement perhydrolysis
constant. This document teaches that the bleaching agent should prefer-
ably be separated from bleach-stabilizing ingredients. If the bleaching
agent is perborate and if a diacylated or polyacylated amine bleach
activator is used, this measure is actually compulsory.
European patent application EP 481 793 (Unilever) also describes
detergent tablets. These detergent tablets contain sodium percarbonate as
bleaching agent which is spatially separated from all those substances
which can adversely affect its stability. This document also refers specifi-
cally to the separation of bleaching agent and bleach activator or
substances which can be attacked by bleaching agents and, in the
process, lead to a loss of bleaching activity.
European patent application EP 395 333 (Unilever) describes tablet
ted detergent compositions containing sodium perborate and one or more
substances from the group of diacylated or polyacylated amine bleach
activators, enzymes and optical brighteners, the persalt not being
separated from the substances of this group. The tablets disclosed in this
application are stable and do not show any loss of bleaching agent or
enzyme activity.
Earlier German patent application DE 198 06 220.6 (Henkel KGaA)
describes two-phase or multiple-phase detergent tablets of compacted
particulate detergent containing builder(s), bleaching agent, bleach
activators) and optionally other detergent ingredients in which the bleach
activators) is/are accommodated in a region of the tablet separated from
oxidation-sensitive ingredients.
CA 02300016 2000-02-25
3
In the prior art literature, the problems of bleach stability and the
stability of oxidation-sensitive ingredients in detergent tablets are
attributed
to the contact between bleaching agent and the ingredients in question.
The separation of the bleaching agent from the bleach activator or from
oxidation-sensitive ingredients is repeatedly proposed as a solution to the
problem. None of the cited documents is concerned with other ways of
simultaneously overcoming stability problems of oxidation-sensitive ingre-
dients and the loss of activity of the bleaching agent or other active
ingredients, for example enzymes, in detergent tablets.
Now, the problem addressed by the present invention was to provide
detergent tablets which would overcome the problems mentioned. In
particular, the stability problems of oxidation-sensitive ingredients such as,
for example, dyes, optical brighteners, perfumes and enzymes would be
overcome and the loss of activity of the bleaching agent, even over long
periods, would be overcome without the tablet having to be divided up into
several regions.
It has now been found that the hygroscopicity of the tablets or rather
the premixes to be tabletted has a crucial bearing both on the decompo-
sition of oxidation-sensitive ingredients and on the loss of activity of the
bleaching agent.
The present invention relates to detergent tablets of compacted
particulate detergent containing builders, bleaching agents and other
typical ingredients, characterized in that the water absorption of the tablet
after storage in the open for one week at 30°C/80% relative air
humidity is
more than 2 g per 10 g.
The expression "detergent tablet" in the context of the present
invention is not meant to be limiting in any way. As already mentioned,
"detergent tablets" include laundry detergent tablets, dishwasher tablets,
tablets for cleaning hard surfaces and tabletted washing aids. The water
absorption of the tablets, which is also referred to in the context of the
CA 02300016 2000-02-25
4
present invention as the hygroscopicity of the tablets or HT for short, may
be experimentally determined by storing a well-balanced tablet in the open
for one week at 30°C/80% relative air humidity, subsequently weighing
the
tablet and then calculating the difference between the weights. The tablet
hygroscopicity is expressed as the increase in weight (water absorption) in
g per 10 g of tablet weight.
In preferred detergent tablets, the hygroscopicity value HT is higher
than the lower limit mentioned above. According to the invention, preferred
detergent tablets are characterized in that the water absorption of the tablet
after storage in the open for one week at 30°C/80% relative air
humidity is
more than 2.25 g, preferably more than 2.5 g and more preferably more
than 2.75 g per 10 g.
As mentioned above, the hygroscopicity value HT is an experiment
ally determined value which is determined by storing and weighing the
tablet. The disadvantage of this method is that, although a tablet with a
water absorption of less than 2 g per 10 g of tablet weight can be
recognized as problematical in regard to stability, the production of this
tablet was not suspended. Accordingly, it would be desirable to be able to
predict before production of the premixes to be tabletted whether the
tablets fulfil the hygroscopicity criterion and whether modifications to the
formulation need to be made to fulfil that criterion. In this way, it would be
possible before tabletting to avoid faulty batches through mixing of the
premixes with other ingredients.
It has been found that, besides the experimental hygroscopicity
value HT, a calculated hygroscopicity value H~,° can also be used. In
this
way, the hygroscopicity Hraw mate~a~ can be determined for each individual
raw material present in the premix by storage for one week at 30°C/80%
relative air humidity. The calculated hygroscopicity value H~,,° of the
premix to be tabletted is thus the percentage-content-weighted sum of the
individual hygroscopicity values:
CA 02300016 2000-02-25
Hcalc = ~ xraw material ' Hraw material
The calculated hygroscopicity value H~,° of the premix has a
different limit
5 than the experimentally determined hygroscopicity value HT of the actual
tablet. This results from the greater compaction of the individual
hygroscopic ingredients in the tablet.
The present invention also relates to detergent tablets in which the
sum of the water absorption values of the individual raw materials of the
tablet after storage in the open for one week at 30°C/80% relative air
humidity, multiplied by their percentage content in the tablet, is more than 5
g per 10 g.
Accordingly, it is possible using the calculated hygroscopicity
H~,° to
prepare premixes of which the tabletting provides tablets which satisfy the
criteria the experimentally determined hygroscopicity HT is expected to
fulfil. In the case of the calculated hygroscopicity also, the hygroscopicity
value H~,° in preferred detergent tablets is higher than the lower
limit
mentioned above. According to the invention, preferred detergent tablets
are characterized in that the sum of the water absorption values of the
individual raw materials of the tablet after storage in the open for one week
at 30°C/80% relative air humidity, multiplied by their percentage
content in
the tablet, is more than 5.25 g, preferably more than 5.5 g and more
preferably more than 5.75 g per 10 g.
Besides builders and optionally other typical detergent ingredients,
the detergent tablets according to the invention contain bleaching agents of
which the stability is improved by keeping to the hygroscopicity limits.
Among the compounds yielding H202 in water which serve as
bleaching agents, sodium perborate tetrahydrate and sodium perborate
monohydrate are particularly important. Other useful bleaching agents are,
for example, sodium percarbonate, peroxypyrophosphates, citrate perhy-
CA 02300016 2000-02-25
6
drates and H202-yielding peracidic salts or peracids, such as
perbenzoates, peroxophthalates, diperazelaic acid, phthaloiminoperacid or
diperdodecane dioic acid. If detergent or bleach tablets for dishwashing
machines are being produced, bleaching agents from the group of organic
bleaches may also be used. Typical organic bleaching agents are diacyl
peroxides, such as dibenzoyl peroxide for example. Other typical organic
bleaching agents are the peroxy acids, of which alkyl peroxy acids and aryl
peroxy acids are particularly mentioned as examples. Preferred
representatives are (a) peroxybenzoic acid and ring-substituted derivatives
thereof, such as alkyl peroxybenzoic acids, but also peroxy-a-naphthoic
acid and magnesium monoperphthalate, (b) aliphatic or substituted
aliphatic peroxy acids, such as peroxylauric acid, peroxystearic acid, E-
phthalimidoperoxycaproic acid [phthaloiminoperoxyhexanoic acid (PAP)],
o-carboxybenzamidoperoxycaproic acid, N-nonenylamidoperadipic acid
and N-nonenylamidopersuccinates, and (c) aliphatic and araliphatic
peroxydicarboxylic acids, such as 1,12-diperoxycarboxylic acid, 1,9-
diperoxyazelaic acid, diperoxysebacic acid, diperoxybrassylic acid,
diperoxyphthalic acids, 2-decyldiperoxybutane-1,4-dioic acid, N,N-
terephthaloyl-di(6-aminopercaproic acid).
Other suitable bleaching agents in dishwasher tablets are chlorine-
and bromine-releasing substances. Suitable chlorine- or bromine-releasing
materials are, for example, heterocyclic N-bromamides and N-chloramides,
for example trichloroisocyanuric acid, tribromoisocyanuric acid, dibromo-
isocyanuric acid and/or dichloroisocyanuric acid (DICA) and/or salts thereof
with cations, such as potassium and sodium. Hydantoin compounds, such
as 1,3-dichloro-5,5-dimethyl hydantoin, are also suitable.
In preferred detergent tablets, the bleaching agent is selected from
the groups of oxygen bleaching agents, more particularly sodium perborate
monohydrate, sodium perborate tetrahydrate and sodium percarbonate,
and/or halogen bleaching aents, more particularly chlorine bleaching
CA 02300016 2000-02-25
7
agents, of which trichlorocyanuric acids, dichloro- and monochloro-
cyanurates and hypochlorites are particularly preferred.
Stabilizing bleaching agents was one aspect of the present
invention. Another aspect was stabilizing other sensitive ingredients, more
particularly enzymes. It has been found that, in contrast to the stability of
bleaching agents, the stability of enzymes is better at low hygroscopicity
values. Accordingly, the present invention relates to detergent tablets of
compacted particulate detergent containing builders, enzymes and other
typical ingredients, characterized in that the water absorption of the tablet
after storage in the open for one week at 30°C/80% relative air
humidity is
less than 2 g per 10 g.
Accordingly, in the case of enzyme-containing detergent tablets, the
hygroscopicity value HT is an upper limit whereas, in the case of the
bleach-containing detergent tablets described above, it represented a lower
limit. In preferred enzyme-containing tablets, the hygroscopicity value is
below that mentioned above. According to the invention, preferred
detergent tablets are characterized in that the water absorption of the tablet
after storage in the open for one week at 30°C/80% relative air
humidity is
less than 1.75 g, preferably less than 1.5 g and more preferably less than
1.25 g per 10 g.
In exactly the same way as for the bleach-containing tablets
described above, the experimentally determined hygroscopicity value can
also be replaced by a calculated hygroscopicity value in the case of the
enzyme-containing detergent tablets. Accordingly, the present invention
also relates to detergent tablets in which the sum of the water absorption
values of the individual raw materials of the tablet after storage in the open
for one week at 30°C/80% relative air humidity, multiplied by their
percentage content in the tablet, is less than 5 g per 10 g.
In these cases, too, the upper limit is preferably lower, so that
preferred detergent tablets are those where the sum of the water
CA 02300016 2000-02-25
8
absorption values of the individual raw materials of the tablet after storage
in the open for one week at 30°CI80% relative air humidity, multiplied
by
their percentage content in the tablet, is less than 4.75 g, preferably less
than 4.5 g and more preferably less than 4.25 g per 10 g.
Besides builders and optionally other typical detergent ingredients,
the detergent tablets according to the invention contain enzymes of which
the stability is improved by keeping to the hygroscopicity limits.
Suitable enzymes are, in particular, those from the classes of
hydrolases, such as proteases, esterases, lipases or lipolytic enzymes,
amylases, glycosyl hydrolases and mixtures thereof. All these hydrolases
contribute to the removal of stains, such as protein-containing, fat-
containing or starch-containing stains. Oxidoreductases may also be used
for bleaching. Enzymes obtained from bacterial strains or fungi, such as
Bacillus subtilis, Bacillus licheniformis, Streptomyces griseus, Coprinus
cinereus and Humicola insolens and from genetically modified variants are
particularly suitable. Proteases of the subtilisin type are preferably used,
proteases obtained from Bacillus lentus being particularly preferred. Of
particular interest in this regard are enzyme mixtures, for example of
protease and amylase or protease and lipase or lipolytic enzymes or of
protease and cellulase or of cellulase and lipase or lipolytic enzymes or of
protease, amylase and lipase or lipolytic enzymes or protease, lipase or
lipolytic enzymes and cellulase, but especially protease- and/or lipase-
containing mixtures or mixtures with lipolytic enzymes. Examples of such
lipolytic enzymes are the known cutinases. Peroxidases or oxidases have
also been successfully used in some cases. Suitable amylases include in
particular a-amylases, isoamylases, pullanases and pectinases.
The enzymes may be adsorbed to supports and/or encapsulated in
shell-forming substances to protect them against premature decomposition.
The percentage content of the enzymes, enzyme mixtures or enzyme
granules may be, for example, from about 0.1 to 5% by weight and is
CA 02300016 2000-02-25
9
preferably from 0.5 to about 4.5% by weight.
In preferred detergent tablets, the enzymes are selected from the
groups of proteases, lipases, amylases, glycosyl hydrolases and mixtures
thereof.
Both the bleach-containing and the enzyme-containing detergent
tablets contain builders) as further ingredient(s). Besides the detersive
substances, builders are the most important ingredients of detergents. The
detergent tablets according to the invention may contain any of the builders
typically used in detergents, i.e. in~particular zeolites, silicates,
carbonates,
organic cobuilders and phosphates.
Crystalline layer-form sodium silicates suitable as builders
correspond to the general formula NaMSiXO~+~A y H20, where M is sodium
or hydrogen, x is a number of 1.9 to 4 and y is a number of 0 to 20,
preferred values for x being 2, 3 or 4. Crystalline layer silicates such as
these are described, for example, in European patent application EP-A-0
164 514. Preferred crystalline layer silicates corresponding to the above
formula are those in which M is sodium and x assumes the value 2 or 3.
Both (i- and 8-sodium disilicates Na2Si205A y H20 are particularly
preferred, ~-sodium disilicate being obtainable, for example, by the process
described in International patent application WO-A- 91108171.
Other useful builders are amorphous sodium silicates with a
modulus (Na20:Si02 ratio) of 1:2 to 1:3.3, preferably 1:2 to 1:2.8 and more
preferably 1:2 to 1:2.6 which dissolve with delay and exhibit multiple wash
cycle properties. The delay in dissolution in relation to conventional
amorphous sodium silicates can have been obtained in various ways, for
example by surface treatment, compounding, compacting or by overdrying.
In the context of the invention, the term "amorphous" is also understood to
encompass "X-ray amorphous". In other words, the silicates do not
produce any of the sharp X-ray reflexes typical of crystalline substances in
X-ray diffraction experiments, but at best one or more maxima of the
CA 02300016 2000-02-25
scattered X-radiation which have a width of several degrees of the
diffraction angle. However, particularly good builder properties may even
be achieved where the silicate particles produce crooked or even sharp
diffraction maxima in electron diffraction experiments. This may be
5 interpreted to mean that the products have microcrystalline regions
between 10 and a few hundred nm in size, values of up to at most 50 nm
and, more particularly, up to at most 20 nm being preferred. So-called X-
ray amorphous silicates such as these, which also dissolve with delay in
relation to conventional waterglasses, are described for example in
10 German patent application DE-A-44 00 024. Compacted amorphous
silicates, compounded amorphous silicates and overdried X-ray-amorphous
silicates are particularly preferred.
If desired, more zeolite besides the quantity of zeolite P and/or X
introduced through the surfactant granules may be incorporated in the
premix by adding zeolite as an aftertreatment component. The finely
crystalline, synthetic zeolite containing bound water used in accordance
with the invention is preferably a zeolite of the A, P, X or Y type. However,
zeolite X and mixtures of A, X and/or P are also suitable. Suitable zeolites
have a mean particle size of less than 10 wm (volume distribution, as
measured by the Coulter Counter Method) and contain preferably 18 to
22% by weight and more preferably 20 to 22% by weight of bound water.
The generally known phosphates may of course also be used as
builders providing their use should not be avoided on ecological grounds.
The sodium salts of the orthophosphates, the pyrophosphates and, in
particular, the tripolyphosphates are particularly suitable.
Organic cobuilders which may be used in the detergent tablets
according to the invention include, in particular, polycarboxy-
lates/polycarboxylic acids, polymeric polycarboxylates, aspartic acid,
polyacetals, dextrins, other organic cobuilders (see below) and
phosphonates. Substances belonging to these classes are described in
CA 02300016 2000-02-25
11
the following.
Useful organic builders are, for example, the polycarboxylic acids
usable, for example, in the form of their sodium salts (polycarboxylic acids
in this context being understood to be carboxylic acids carrying more than
one acid function). Examples include citric acid, adipic acid, succinic acid,
glutaric acid, malic acid, tartaric acid, malefic acid, fumaric acid, sugar
acids, aminocarboxylic acids, nitrilotriacetic acid (NTA), providing its use
is
not ecologically unsafe, and mixtures thereof. Preferred salts are the salts
of the polycarboxylic acids, such as citric acid, adipic acid, succinic acid,
glutaric acid, tartaric acid, sugar acids and mixtures thereof.
The acids per se may also be used. Besides their builder effect, the
acids typically have the property of an acidifying component and,
accordingly, are also used to establish a lower and more mild pH value in
laundry or dishwashing detergents. Citric acid, succinic acid, glutaric acid,
adapic acid, gluconic acid and mixtures thereof are particularly mentioned
in this regard.
Other suitable builders are polymeric polycarboxylates such as, for
example, the alkali metal salts of polyacrylic acid or polymethacrylic acid,
for example those having a relative molecular weight of 500 to 70,000
g/mole.
The molecular weights mentioned in this specification for polymeric
polycarboxylates are weight-average molecular weights MW of the particular
acid form which, basically, were determined by gel permeation
chromatography (GPC) using a UV detector. The measurement was
carried out against an external polyacrylic acid standard which provides
realistic molecular weight values by virtue of its structural similarity to
the
polymers investigated. These values differ distinctly from the molecular
weights measured against polystyrene sulfonic acids as standard. The
molecular weights measured against polystyrene sulfonic acids are
generally far higher than the molecular weights mentioned in this
CA 02300016 2000-02-25
12
specification.
Suitable polymers are, in particular, polyacrylates which preferably
have a molecular weight of 2,000 to 20,000 g/mole. By virtue of their
superior solubility, preferred representatives of this group are the short-
chain polyacrylates which have molecular weights of 2,000 to 10,000
g/mole and, more particularly, 3,000 to 5,000 g/mole.
Also suitable are copolymeric polycarboxylates, particularly those of
acrylic acid with methacrylic acid and those of acrylic acid or methacrylic
acid with malefic acid. Acrylic acid/maleic acid copolymers containing 50 to
90% by weight of acrylic acid and 50 to 10% by weight of malefic acid have
proved to be particularly suitable. Their relative molecular weights, based
on the free acids, are generally in the range from 2,000 to 70,000 g/mole,
preferably in the range from 20,000 to 50,000 g/mole and more preferably
in the range from 30,000 to 40,000 g/mole.
The (co)polymeric polycarboxylates may be used either in powder
form or in the form of an aqueous solution. The content of (co)polymeric
polycarboxylates in the compositions is preferably between 0.5 and 20% by
weight and more preferably between 3 and 10% by weight.
In order to improve their solubility in water, the polymers may also
contain ally) sulfonic acids, for example allyloxybenzenesulfonic acid and
methallyl sulfonic acid as monomer.
Biodegradable polymers of more than two different monomer units
are also particularly preferred, examples including those which contain
salts of acrylic acid and malefic acid and vinyl alcohol or vinyl alcohol
derivatives as monomers or those which contain salts of acrylic acid and 2-
alkylallyl sulfonic acid and sugar derivatives as monomers.
Other preferred copolymers are those described in German patent
applications DE-A-43 03 320 and DE-A-4417 734 which preferably contain
acrolein and acrylic acid/acrylic acid salts or acrolein and vinyl acetate as
monomers.
CA 02300016 2000-02-25
13
Other preferred builders are polymeric aminodicarboxilic acids, salts
or precursors thereof. Polyaspartic acids or salts and derivatives thereof
which, according to German patent application DE-A-195 40 086, have a
bleach-stabilizing effect in addition to their co-builder properties are
particularly preferred.
Other suitable builders are polyacetals which may be obtained by
reaction of dialdehydes with polyol carboxylic acids containing 5 to 7
carbon atoms and at least three hydroxyl groups. Preferred polyacetals are
obtained from dialdehydes, such as glyoxal, glutaraldehyde, terephthal-
aldehyde and mixtures thereof and from polyol carboxylic acids, such as
gluconic acid and/or glucoheptonic acid.
Other suitable organic builders are dextrins, for example oligomers
or polymers of carbohydrates which may be obtained by partial hydrolysis
of starches. The hydrolysis may be carried out by standard methods, for
example acid- or enzyme-catalyzed methods. The end products are
preferably hydrolysis products with average molecular weights of 400 to
500,000 g/mole. A polysaccharide with a dextrose equivalent (DE) of 0.5 to
40 and, more particularly, 2 to 30 is preferred, the DE being an accepted
measure of the reducing effect of a polysaccharide by comparison with
dextrose which has a DE of 100. Both maltodextrins with a DE of 3 to 20
and dry glucose sirups with a DE of 20 to 37 and also so-called yellow
dextrins and white dextrins with relatively high molecular weights of 2,000
to 30,000 g/mole may be used.
The oxidized derivatives of such dextrins are their reaction products
with oxidizing agents which are capable of oxidizing at least one alcohol
function of the saccharide ring to the carboxylic acid function. Dextrins thus
oxidized and processes for their production are known, for example, from
European patent applications EP-A-0 232 202, EP-A-0 427 349, EP-A-0
472 042 and EP-A-0 542 496 and from International patent applications
WO 92/18542, WO 93108251, WO 94!28030, WO 95107303, WO 95112619
CA 02300016 2000-02-25
14
and WO 95120608. An oxidized oligosaccharide according to German
patent application DE-A-196 00 018 is also suitable. A product oxidized at
C6 of the saccharide ring can be particularly advantageous.
Other suitable co-builders are oxydisuccinates and other derivatives
of disuccinates, preferably ethylenediamine disuccinate. Ethylenediamine
N,N'-disuccinate (EDDS) is preferably used in the form of its sodium or
magnesium salts. Glycerol disuccinates and glycerol trisuccinates are also
particularly preferred in this connection. The quantities used in zeolite
containing and/or silicate-containing formulations are from 3 to 15% by
weight.
Other useful organic co-builders are, for example, acetylated
hydroxycarboxylic acids and salts thereof which may optionally be present
in lactone form and which contain at least 4 carbon atoms, at least one
hydroxy group and at most two acid groups. Co-builders such as these are
described, for example, in International patent application WO 95/20029.
Another class of substances with co-builder properties are the
phosphonates, more particularly hydroxyalkane and aminoalkane phos-
phonates. Among the hydroxyalkane phosphonates, 1-hydroxyethane-1,1-
diphosphonate (HEDP) is particularly important as a co-builder. It is
preferably used in the form of a sodium salt, the disodium salt showing a
neutral reaction and the tetrasodium salt an alkaline ration (pH 9).
Preferred aminoalkane phosphonates are ethylenediamine tetramethylene
phosphonate (EDTMP), diethylenetriamine pentamethylene phosphonate
(DTPMP) and higher homologs thereof. They are preferably used in the
form of the neutrally reacting sodium salts, for example as the hexasodium
salt of EDTMP and as the hepta- and octasodium salt of DTPMP. Within
the class of phosphonates, HEDP is preferably used as builder. The
aminoalkane phosphonates also show a pronounced heavy metal binding
capacity. Accordingly, it can be of advantage, particularly where the
detergents also contain bleaching agents, to use aminoalkane
CA 02300016 2000-02-25
phosphonates, more especially DTPMP, or mixtures of the phosphonates
mentioned.
In addition, any compounds capable of forming complexes with
alkaline earth metal ions may be used as co-builders.
5 As described above, water-soluble and water-insoluble builders may
be used in detergent tablets according to the invention, above all to bind
calcium and magnesium. Water-soluble builders are preferably used
because, in general, they tend less to form insoluble residues on tableware
and hard surfaces. Typical builders which may be present in accordance
10 with the invention in quantities of 10 to 90% by weight, based on the
preparation as a whole, are the low molecular weight polycarboxylic acids
and salts thereof, the homopolymeric and copolymeric polycarboxylic acids
and salts thereof, the carbonates, phosphates and silicates. Water-
insoluble builders include the zeolites, which may also be used, and
15 mixtures of the above-mentioned builders.
Trisodium citrate and/or pentasodium tripolyphosphate and/or
sodium carbonate and/or sodium bicarbonate and/or gluconates and/or
silicate builders from the class of disilicates and/or metasilicates are
preferably used.
Alkalinity sources may be present as further ingredients. Alkalinity
sources are alkali metal hydroxides, alkali metal carbonates, alkali metal
hydrogen carbonates, alkali metal sesquicarbonates, alkali metal silicates,
alkali metal metasilicates and mixtures of the substances mentioned above.
According to the invention, alkali metal carbonates, more particularly
sodium carbonate, sodium hydrogen carbonate or sodium sesqui-
carbonate, are preferably used.
A builder system containing a mixture of tripolyphosphate and
sodium carbonate is particularly preferred.
Another particularly preferred builder system contains a mixture of
tripolyphosphate and sodium carbonate and sodium disilicate.
CA 02300016 2000-02-25
16
In summary, preferred detergent tablets according to the invention
are characterized in that they contain 20 to 95% by weight, preferably 30 to
90% by weight and more preferably 40 to 85% by weight of one or more
builders from the group of phosphates, more especially pentasodium
tripotyphosphate, silicates, more particularly disilicates and/or
metasilicates, zeolites, carbonates and/or hydrogen carbonates, low
molecular weight polycarboxylic acids and salts thereof, more particularly
citrates, homo- or copolymeric polycarboxylic acids and salts thereof and
gluconates.
In addition to the bleaching agent and/or enzymes and the builders,
the detergent tablets according to the invention may contain other typical
detergent ingredients, including in particular surfactants, bleach activators,
corrosion inhibitors or silver protectors, pH regulators, perfumes, perfume
carriers, fluorescers, dyes, foam inhibitors, silicone oils, redeposition
inhibitors, optical brighteners, discoloration inhibitors and dye transfer
inhibitors.
The detergent tablets according to the invention may contain anionic
and nonionic surfactants, for example, as surfactants in quantities which
vary considerably according to the application envisaged for the tablets.
The classes of surfactants mentioned are described in the following.
Suitable anionic surfactants are, for example, those of the sulfonate
and sulfate type. Suitable surfactants of the sulfonate type are preferably
C~~3 alkyl benzenesulfonates, olefin sulfonates, i.e. mixtures of alkene and
hydroxyalkane sulfonates, and the disulfonates obtained, for example, from
C~2_~8 monoolefins with an internal or terminal double bond by sulfonation
with gaseous sulfur trioxide and subsequent alkaline or acidic hydrolysis of
the sulfonation products. Other suitable surfactants of the sulfonate type
are the alkane sulfonates obtained from C~Z_~$ alkanes, for example by
sulfochlorination or sulfoxidation and subsequent hydrolysis or
neutralization. The esters of a-sulfofatty acids (ester sulfonates), for
CA 02300016 2000-02-25
17
example the a-sulfonated methyl esters of hydrogenated coconut oil, palm
kernel oil or tallow fatty acids, are also suitable.
Other suitable anionic surfactants are sulfonated fatty acid glycerol
esters. Fatty acid glycerol esters in the context of the present invention are
the monoesters, diesters and triesters and mixtures thereof which are
obtained where production is carried out by esterification of a monoglycerol
with 1 to 3 moles of fatty acid or in the transesterification of triglycerides
with 0.3 to 2 moles of glycerol. Preferred sulfonated fatty acid glycerol
esters are the sulfonation products of saturated fatty acids containing 6 to
22 carbon atoms, for example caproic acid, caprylic acid, capric acid,
myristic acid, lauric acid, palmitic acid, stearic acid or behenic acid.
Preferred alk(en)yl sulfates are the alkali metal salts and, in
particular, the sodium salts of the sulfuric acid semiesters of C,2_~8 fatty
alcohols, for example coconut fatty alcohol, tallow fatty alcohol, lauryl,
myristyl, cetyl or stearyl alcohol, or C~o_2o oxoalcohols and the corre
sponding semiesters of secondary alcohols with the same chain length.
Other preferred alk(en)yl sulfates are those with the chain length mentioned
which contain a synthetic, linear alkyl chain based on a petrochemical and
which are similar in their degradation behavior to the corresponding
compounds based on oleochemical raw materials. C~2_~s alkyl sulfates,
C~2_~5 alkyl sulfates and C~4_~5 alkyl sulfates are preferred from the point
of
view of washing technology. Other suitable anionic surfactants are 2,3-
alkyl sulfates which may be produced, for example, in accordance with US
3,234,258 or US 5,075,041 and which are commerially obtainable as
products of the Shell Oil Company under the name of DAN~.
The sulfuric acid monoesters of linear or branched C~_2~ alcohols
ethoxylated with 1 to 6 moles of ethylene oxide, such as 2-methyl-branched
C~~~ alcohols containing on average 3.5 moles of ethylene oxide (EO) or
C~2_~8 fatty alcohols containing 1 to 4 EO, are also suitable. In view of
their
high foaming capacity, they are only used in relatively small quantities, for
CA 02300016 2000-02-25
18
example in quantities of 1 to 5% by weight, in dishwashing detergents.
Other suitable anionic surfactants are the salts of alkyl sulfosuccinic
acid which are also known as sulfosuccinates or as sulfosuccinic acid
esters and which represent monoesters and/or diesters of sulfosuccinic
acid with alcohols, preferably fatty alcohols and, more particularly,
ethoxylated fatty alcohols. Preferred sulfosuccinates contain C8_~8 fatty
alcohol residues or mixtures thereof. Particularly preferred sulfosuccinates
contain a fatty alcohol residue derived from ethoxylated fatty alcohols
which, considered in isolation, represent nonionic surfactants (for a
description, see below). Of these sulfosuccinates, those of which the fatty
alcohol residues are derived from narrow-range ethoxylated fatty alcohols
are particularly preferred. Alk(en)yl succinic acid preferably containing 8 to
18 carbon atoms in the alk(en)yl chain or salts thereof may also be used.
Other suitable anionic surfactants are, in particular, soaps. Suitable
soaps are saturated fatty acid soaps, such as the salts of lauric acid,
myristic acid, palmitic acid, stearic acid, hydrogenated erucic acid and
behenic acid, and soap mixtures derived in particular from natural fatty
acids, for example coconut, palm kernel or tallow fatty acids.
The anionic surfactants, including the soaps, may be present in the
form of their sodium, potassium or ammonium salts and as soluble salts of
organic bases, such as mono-, di- or triethanolamine. The anionic
surfactants are preferably present in the form of their sodium or potassium
salts and, more preferably, in the form of their sodium salts.
If laundry detergent tablets according to the invention are being
produced, their anionic surfactant content is preferably above 5% by
weight, more preferably above 7.5% by weight and most preferably above
10% by weight, based on tablet weight.
So far as the choice of anionic surfactants is concerned, there are
no basic requirements to restrict the freedom of formulation. However,
preferred laundry detergent tablets do have a soap content in excess of
CA 02300016 2000-02-25
19
0.2% by weight, based on the total weight of the detergent tablets.
Preferred anionic surfactants are alkyl benzenesulfonates and fatty alcohol
sulfates, preferred laundry detergent tablets containing 2 to 20% by weight,
preferably 2.5 to 15% by weight and more preferably 5 to 10% by weight of
fatty alcohol sulfate(s), based on the weight of the detergent tablet.
Preferred nonionic surfactants are alkoxylated, advantageously
ethoxylated, more especially primary alcohols preferably containing 8 to 18
carbon atoms and, on average, 1 to 12 moles of ethylene oxide (EO) per
+mole of alcohol, in which the alcohol component may be linear or,
preferably, methyl-branched in the 2-position or may contain linear and
methyl-branched residues in the form of the mixtures typically present in
oxoalcohol residues. However, alcohol ethoxylates containing linear
residues of alcohols of native origin with 12 to 18 carbon atoms, for
example coconut, palm, tallow or oleyl alcohol, and on average 2 to 8 EO
per mole of alcohol are particularly preferred. Preferred ethoxylated
alcohols include, for example, C~2-14 alcohols containing 3 EO or 4 EO,
Cø~~ alcohol containing 7 EO, C~3_~5 alcohols containing 3 EO, 5 EO, 7 EO
or 8 EO, C~2_~8 alcohols containing 3 EO, 5 EO or 7 EO and mixtures
thereof, such as mixtures of C~2_~4 alcohol containing 3 EO and C~2_~$
alcohol containing 5 EO. The degrees of ethoxylation mentioned represent
statistical mean values which, for a special product, can be a whole number
or a broken number. Preferred alcohol ethoxylates have a narrow homolog
distribution (narrow range ethoxylates, NRE). In addition to these nonionic
surfactants, fatty alcohols containing more than 12 EO may also be used,
examples including tallow fatty alcohol containing 14 EO, 25 EO, 30 EO or
40 EO.
Another class of preferred nonionic surfactants which may be used
either as sole nonionic surfactant or in combination with other nonionic
surfactants are alkoxylated, preferably ethoxylated or ethoxylated and
propoxylated, fatty acid alkyl esters preferably containing 1 to 4 carbon
CA 02300016 2000-02-25
atoms in the alkyl chain, more especially the fatty acid methyl esters which
are described, for example, in Japanese patent application JP 581217598
or which are preferably produced by the process described in International
patent application WO-A-90113533.
5 Another class of nonionic surfactants which may advantageously be
used are the alkyl polyglycosides (APGs). Suitable alkyl polyglycosides
correspond to the general formula RO(G)Z where R is a linear or branched,
more particularly 2-methyl-branched, saturated or unsaturated aliphatic
radical containing 8 to 22 and preferably 12 to 18 carbon atoms and G
10 stands for a glycose unit containing 5 or 6 carbon atoms, preferably
glucose. The degree of glycosidation z is between 1.0 and 4.0, preferably
between 1.0 and 2.0 and more preferably between 1.1 and 1.4.
Linear alkyl polyglucosides, i.e. alkyl polyglycosides in which the
polyglycosyl component is a glucose unit and the alkyl component is an n-
15 alkyl group, are preferably used.
Laundry detergent tablets according to the invention in particular
may advantageously contain alkyl polyglycosides, APG contents of more
than 0.2% by weight, based on the tablet as a whole, being preferred.
Particularly preferred detergent tablets contain APGs in quantities of 0.2 to
20 10% by weight, preferably in quantities of 0.2 to 5% by weight and more
preferably in quantities of 0.5 to 3% by weight.
Nonionic surfactants of the amine oxide type, for example N-
cocoalkyl-N,N-dimethylamine oxide and N-tallowalkyl-N,N-dihydroxyethyl-
amine oxide, and the fatty acid alkanolamide type are also suitable. The
quantity in which these nonionic surfactants are used is preferably no more
than the quantity in which the ethoxylated fatty alcohols are used and,
more preferably, no more than half that quantity.
Other suitable surfactants are polyhydroxyfatty acid amides
corresponding to formula (I):
CA 02300016 2000-02-25
21
R'
R-CO-N-[Z] (I)
in which RCO is an aliphatic acyl group containing 6 to 22 carbon atoms,
R' is hydrogen, an alkyl or hydroxyalkyl group containing 1 to 4 carbon
atoms and [Z] is a linear or branched polyhydroxyalkyl group containing 3
to 10 carbon atoms and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid
amides are known substances which may normally be obtained by
reductive amination of a reducing sugar with ammonia, an alkylamine or an
alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl
ester or a fatty acid chloride.
The group of polyhydroxyfatty acid amides also includes compounds
corresponding to formula (II):
R'-O-R2
R-CO-N-[Z] (I I)
in which R is a linear or branched alkyl or alkenyl group containing 7 to 12
carbon atoms, R' is a linear, branched or cyclic alkyl group or an aryl group
containing 2 to 8 carbon atoms and R2 is a linear, branched or cyclic alkyl
group or an aryl group or an oxyalkyl group containing 1 to 8 carbon atoms,
C~~ alkyl or phenyl groups being preferred, and [Z] is a linear polyhydroxy-
alkyl group, of which the alkyl chain is substituted by at least two hydroxyl
groups, or alkoxylated, preferably ethoxylated or propoxylated, derivatives
of that group.
[Z] is preferably obtained by reductive amination of a reduced sugar,
for example glucose, fructose, maltose, lactose, galactose, mannose or
xylose. The N-alkoxy- or N-aryloxy-substituted compounds may then be
converted into the required polyhydroxyfatty acid amides by reaction with
fatty acid methyl esters in the presence of an alkoxide as catalyst, for
CA 02300016 2000-02-25
22
example in accordance with the teaching of International patent application
WO-A-95107331.
If laundry detergent tablets according to the invention are being
produced, their nonionic surfactant content is preferably above 2% by
weight, more preferably above 5% by weight and most preferably above
7.5% by weight, based on tablet weight.
In order to obtain an improved bleaching effect where washing is
carried out at temperatures of 60°C or lower, bleach activators may be
incorporated as sole constituent or as an ingredient of component b). The
bleach activators may be compounds which form aliphatic peroxocarboxylic
acids containing preferably 1 to 10 carbon atoms and more preferably 2 to
4 carbon atoms and/or optionally substituted perbenzoic acid under
perhydrolysis conditions. Substances bearing O- and/or N-acyl groups with
the number of carbon atoms mentioned and/or optionally substituted
benzoyl groups are suitable. Preferred bleach activators are polyacylated
alkylenediamines, more particularly tetraacetyl ethylenediamine (TAED),
acylated triazine derivatives, more particularly 1,5-diacetyl-2,4-dioxohexa-
hydro-1,3,5-triazine (DADHT), acylated glycolurils, more particularly
tetraacetyl glycoluril (TAGU), N-acylimides, more particularly N-nonanoyl
succinimide (NOSI), acylated phenol sulfonates, more particularly n-
nonanoyl or isononanoyloxybenzenesulfonate (n- or iso-NOBS), carboxylic
anhydrides, more particularly phthalic anhydride, acylated polyhydric
alcohols, more particularly triacetin, ethylene glycol diacetate and 2,5-
diacetoxy-2,5-dihydrofuran.
In addition to or instead of the conventional bleach activators
mentioned above, so-called bleach catalysts may also be incorporated in
the tablets. Bleach catalysts are bleach-boosting transition metal salts or
transition metal complexes such as, for example, manganese-, iron-,
cobalt-, ruthenium- or molybdenum-salen complexes or carbonyl
complexes. Manganese, iron, cobalt, ruthenium, molybdenum, titanium,
CA 02300016 2000-02-25
23
vanadium and copper complexes with nitrogen-containing tripod ligands
and cobalt-, iron-, copper- and ruthenium-ammine complexes may also be
used as bleach catalysts.
Preferred laundry and dishwashing detergent tablets according to
the invention additionally contain a bleach activator, preferably from the
group of polyacylated alkylenediamines, more particularly tetraacetyl
ethylenediamine (TAED), N-acyl imides, more particularly N-nonanoyl
succinimide (NOSI), acylated phenol sulfonates, more particularly n
nonanoyl or isononanoyloxybenzenesulfonate (n- or iso-NOBS), MMA
and/or the group of manganese and/or cobalt salts and/or complexes, more
preferably the cobalt (ammine) complexes, cobalt (acetate) complexes,
cobalt (carbonyl) complexes, chlorides of cobalt or manganese and
manganese sulfate, preferably in quantities of 1 % by weight to 10% by
weight and more preferably in quantities of 2% by weight to 8% by weight,
based on the tablet weight.
Dishwasher tablets according to the invention may contain corrosion
inhibitors to protect the tableware or the machine itself, silver protectors
being particularly important for machine dishwashing. Above all, silver
protectors selected from the group of triazoles, benzotriazoles,
bisbenzotriazoles, aminotriazoles, alkylaminotriazoles and the transition
metal salts or complexes may generally be used. Benzotriazole and/or
alkylaminotriazole is/are particularly preferred. According to the documents
cited above, oxygen- and nitrogen-containing organic redox-active
compounds, such as dihydric and trihydric phenols, for example
hydroquinone, pyrocatechol, hydroxyhydroquinone, gallic acid, phloro-
glucinol, pyrogallol and derivatives of these compounds, are particularly
useful. Salt-like and complex-like inorganic compounds, such as salts of
the metals Mn, Ti, Zr, Hf, V, Co and Ce are also frequently used. Of these,
the transition metal salts selected from the group of manganese and/or
cobalt salts and/or complexes are preferred, cobalt(ammine) complexes,
CA 02300016 2000-02-25
24
cobalt(acetate) complexes, cobalt(carbonyl) complexes, chlorides of cobalt
or manganese and manganese sulfate being particularly preferred. Zinc
compounds may also be used to prevent corrosion of tableware.
Preferred laundry and dishwasher detergent tablets according to the
invention are characterized in that at least one silver protector selected
from the group of triazoles, benzotriazoles, bisbenztotriazoles,
aminotriazoles alkylamiotriazoles, preferably benzotriazole and/or
alkylaminotriazole, is additionally present.
Besides the builders, the bleaching agent and/or the enzymes and
the surfactants and bleach activators optionally used, the
laundry/dishwasher detergent tablets according to the invention may
contain other detergent ingredients, for example disintegration aids, dyes
and perfumes, etc. These substances are described in the following:
In order to facilitate the disintegration of heavily compacted tablets,
disintegration aids, so-called tablet disintegrators, may be incorporated in
them to shorten their disintegration times. According to Rompp (9th
Edition, Vol. 6, page 4440) and Voigt "Lehrbuch der pharmazeutischen
Technologie" (6th Edition, 1987, pages 182-184), tablet disintegrators or
disintegration accelerators are auxiliaries which promote the rapid
disintegration of tablets in water or gastric juices and the release of the
pharmaceuticals in an absorbable form.
These substances, which are also known as "disintegrators" by
virtue of their effect, are capable of undergoing an increase in volume on
contact with water so that, on the one hand, their own volume is increased
(swelling) and, on the other hand, a pressure can be generated through the
release of gases which causes the tablet to disintegrate into relatively small
particles. Well-known disintegrators are, for example, carbonate/citric acid
systems, although other organic acids may also be used. Swelling
disintegration aids are, for example, synthetic polymers, such as polyvinyl
pyrrolidone (PVP), or natural polymers and modified natural substances,
CA 02300016 2000-02-25
such as cellulose and starch and derivatives thereof, alginates or casein
derivatives.
Preferred detergent tablets contain 0.5 to 10% by weight, preferably
3 to 7% by weight and more preferably 4 to 6% by weight of one or more
5 disintegration aids, based on the weight of the tablet.
According to the invention, preferred disintegrators are cellulose-
based disintegrators, so that preferred detergent tablets contain a
cellulose-based disintegrator in quantities of 0.5 to 10% by weight,
preferably 3 to 7% by weight and more preferably 4 to 6% by weight. Pure
10 cellulose has the formal empirical composition (C6H~o05)n and, formally, is
a ~i-1,4-polyacetal of cellobiose which, in turn, is made up of two molecules
of glucose. Suitable celluloses consist of ca. 500 to 5000 glucose units
and, accordingly, have average molecular weights of 50,000 to 500,000.
According to the invention, cellulose derivatives obtainable from cellulose
15 by polymer-analog reactions may also be used as cellulose-based
disintegrators. These chemically modified celluloses include, for example,
products of esterification or etherification reactions in which hydroxy
hydrogen atoms have been substituted. However, celluloses in which the
hydroxy groups have been replaced by functional groups that are not
20 attached by an oxygen atom may also be used as cellulose derivatives.
The group of cellulose derivatives includes, for example, alkali metal
celluloses, carboxymethyl cellulose (CMC), cellulose esters and ethers and
aminocelluloses. The cellulose derivatives mentioned are preferably not
used on their own, but rather in the form of a mixture with cellulose as
25 cellulose-based disintegrators. The content of cellulose derivatives in
mixtures such as these is preferably below 50% by weight and more
preferably below 20% by weight, based on the cellulose-based
disintegrator. In one particularly preferred embodiment, pure cellulose free
from cellulose derivatives is used as the cellulose-based disintegrator.
The cellulose used as disintegration aid is preferably not used in
CA 02300016 2000-02-25
26
fine-particle form, but is converted into a coarser form, for example by
granulation or compacting, before it is added to and mixed with the
premixes to be tabletted. Detergent tablets which contain granular or
optionally co-granulated disintegrators are described in German patent
applications DE 197 09 991 (Stefan Herzog) and DE 197 10 254 (Henkel)
and in International patent application WO 98140463 (Henkel). Further
particulars of the production of granulated, compacted or co-granulated
cellulose disintegrators can also be found in these patent applications. The
particle sizes of such disintegration aids is mostly above 200 Nm, at least
90% by weight of the particles being between 300 and 1600 Nm in size
and, more particularly, between 400 and 1200 Nm in size. According to the
invention, the above-described relatively coarse-particle cellulose-based
disintegrators described in detail in the cited patent applications are
preferably used as disintegration aids and are commercially obtainable, for
example under the name of Arbocel~ TF-30-HG from Rettenmaier.
Microcrystalline cellulose may be used as another cellulose-based
disintegration aid or as part of such a component. This microcrystalline
cellulose is obtained by partial hydrolysis of celluloses under conditions
which only attack and completely dissolve the amorphous regions (ca. 30%
of the total cellulose mass) of the celluloses, but leave the crystalline
regions (ca. 70%) undamaged. Subsequent de-aggregation of the
microfine celluloses formed by hydrolysis provides the microcrystalline
celluloses which have primary particle sizes of ca. 5 Nm and which can be
compacted, for example, to granules with a mean particle size of 200 Nm.
In addition, laundry detergent tablets according to the invention may
also contain components with a positive effect on the removability of oil and
fats from textiles by washing (so-called soil repellents). This effect
becomes particularly clear when a textile which has already been
repeatedly washed with a detergent according to the invention containing
this oil- and fat-dissolving component is soiled. Preferred oil- and fat-
CA 02300016 2000-02-25
27
dissolving components include, for example, nonionic cellulose ethers,
such as methyl cellulose and methyl hydroxypropyl cellulose containing 15
to 30% by weight of methoxyl groups and 1 to 15% by weight of hydroxy-
propoxyl groups, based on the nonionic cellulose ether, and the polymers
of phthalic acid and/or terephthalic acid known from the prior art or
derivatives thereof, more particularly polymers of ethylene terephthalates
and/or polyethylene glycol terephthalates or anionically and/or nonionically
modified derivatives thereof. Of these, the sulfonated derivatives of
phthalic acid and terephthalic acid polymers are particularly preferred.
Laundry detergent tablets according to the invention may contain
derivatives of diamino-stilbenedisulfonic acid or alkali metal salts thereof
as
optical brighteners. Suitable optical brighteners are, for example, salts of
4,4'-bis-(2-anilino-4-morpholino-1,3,5-triazinyl-6-amino)-stilbene-2,2'-disul-
fonic acid or compounds of similar composition which contain a diethan-
olamino group, a methylamino group, an anilino group or a 2-methoxy-
ethylamino group instead of the morpholino group. Brighteners of the
substituted diphenyl styryl type, for example alkali metal salts of 4,4'-bis-
(2-
sulfostyryl)-diphenyl, 4,4'-bis-(4-chloro-3-sulfostyryl)-diphenyl or 4-(4-
chlorostyryl)-4'-(2-sulfostyryl)-diphenyl, may also be present. Mixtures of
the brighteners mentioned above may also be used.
Dyes and perfumes may be added to the laundry/dishwasher
detergent tablets produced in accordance with the invention to improve the
aesthetic impression created by the products and to provide the consumer
not only with the required washing performance but also with a visually and
sensorially "typical and unmistakable" product. Suitable perfume oils or
perfumes include individual perfume compounds, for example synthetic
products of the ester, ether, aldehyde, ketone, alcohol and hydrocarbon
type. Perfume compounds of the ester type are, for example, benzyl
acetate, phenoxyethyl isobutyrate, p-tert.butyl cyclohexyl acetate, linalyl
acetate, dimethyl benzyl carbinyl acetate, phenyl ethyl acetate, linalyl
CA 02300016 2000-02-25
28
benzoate, benzyl formate, ethyl methyl phenyl glycinate, allyl cyclohexyl
propionate, styrallyl propionate and benzyl salicylate. The ethers include,
for example, benzyl ethyl ether; the aldehydes include, for example, the
linear alkanals containing 8 to 18 carbon atoms, citral, citronellal,
citronellyl-
oxyacetaldehyde, cyclamen aldehyde, hydroxycitronellal, lilial and
bourgeonal; the ketones include, for example, the ionones, 'd-isomethyl
ionone and methyl cedryl ketone; the alcohols include anethol, citronellol,
eugenol, geraniol, linalool, phenyl ethyl alcohol and terpineol and the
hydrocarbons include, above all, the terpenes, such as limonene and
pinene. However, mixtures of various perfumes which together produce an
attractive perfume note are preferably used. Perfume oils such as these
may also contain natural perfume mixtures obtainable from vegetable
sources, for example pine, citrus, jasmine, patchouli, rose or ylang-ylang
oil. Also suitable are clary oil, camomile oil, clove oil, melissa oil, mint
oil,
cinnamon leaf oil, lime blossom oil, juniper berry oil, vetiver oil, olibanum
oil, galbanum oil and labdanum oil and orange blossom oil, neroli oil,
orange peel oil and sandalwood oil.
The detergent tablets according to the invention normally contain
less than 0.01 % by weight of dyes whereas perfumes may make up as
much as 2% by weight of the formulation as a whole.
The perfumes may be directly incorporated in the detergents
according to the invention, although it can also be of advantage to apply
the perfumes to supports which strengthen the adherence of the perfume
to the washing and which provide the textiles with a long-lasting fragrance
through a slower release of the perfume. Suitable support materials are,
for example, cyclodextrins, the cyclodextrin/perfume complexes optionally
being coated with other auxiliaries.
In order to improve their aesthetic impression, the detergents
according to the invention may be colored with suitable dyes. Preferred
dyes, which are not difficult for the expert to choose, have high stability in
CA 02300016 2000-02-25
29
storage, are not affected by the other ingredients of the detergents or by
light and do not have any pronounced substantivity for textile fibers so as
not to color them.
Before the particulate premix is compressed to form detergent
tablets, it may be "powdered" with fine-particle surface treatment materials.
This can be of advantage to the quality and physical properties of both the
premix (storage, tabletting) and the final detergent tablets. Fine-particle
powdering materials have been known for some time in the art, zeolites,
silicates and other inorganic salts generally being used. However, the
compound is preferably "powdered" with fine-particle zeolite, zeolites of the
faujasite type being preferred. In the context of the present invention, the
expression "zeolite of the faujasite type" encompasses all three zeolites
which form the faujasite subgroup of zeolite structural group 4 (cf. Donald
W. Breck: "Zeolite Molecular Sieves" John ~ley & Sons, New
York/London/Sydney/Toronto, 1974, page 92). Besides zeolite X,
therefore, zeolite Y and faujasite and mixtures of these compounds may
also be used, pure zeolite X being preferred.
According to the invention, preferred processes for the production of
detergent tablets are those in which the, or one of the, fine-particle
aftertreatment components subsequently incorporated is a zeolite of the
faujasite type with particle sizes below 100 Nm, preferably below 10 Nm
and more preferably below 5 pm and makes up at least 0.2% by weight,
preferably at least 0.5% by weight and more preferably more than 1 % by
weight of the premix to be compressed.
The present invention provides on the one hand bleach-containing
detergent tablets which have excellent bleach stability through
hygroscopicity values above 2 g per 10 g of tablet and, on the other hand,
enzyme-containing detergent tablets which have excellent enzyme stability
through hygroscopicity values below 2 g per 10 g of tablet, the experiment-
ally determined hygroscopicity values mentioned also being replaceable by
CA 02300016 2000-02-25
calculated hygroscopicity values, as was explained in detail in the
foregoing.
Now, the above-mentioned principles can be embodied in a tablet by
dividing the tablet into at least two regions of which one contains the
5 bleaching agent and has a water absorption capacity of more than 2 g per
10 g while the other region contains the enzymes and has a water
absorption capacity of less than 2 g per 10 g.
Accordingly, the present invention relates to a multiple-phase
detergent tablet of compacted particulate detergent containing builders,
10 bleaching agents, enzymes and other typical ingredients, characterized in
that the bleaching agents) and the enzymes are present in separate
phases and the water absorption of the bleach-containing phases) after
storage in the open for one week at 30°C/80% relative air humidity is
more
than 2 g per 10 g while the water absorption of the enzyme-containing
15 phases) after storage in the open for one week at 30°C/80% relative
air
humidity is less than 2 g per 10 g.
The hygroscopicity values of the multiple-phase tablets according to
the invention are always based on one phase or rather on the premix which
forms that phase after tabletting. In the case of the premixes, the foregoing
20 observations apply to the calculation of the hygroscopicity values. So far
as the individual phases are concerned, experimental hygroscopicity values
are individually determined for each phase, i.e. after separation of the
tablet into its phases.
According to the invention, each of the "individual principles"
25 described above, i.e. excellent bleach stability through hygroscopicity
values above 2 g per 10 g of tablet and, on the other hand, excellent
enzyme stability through hygroscopicity values below 2 g per 10 g of tablet,
may of course also be embodied in multiple-phase tablets which either
contain only bleaching agent or only enzymes. In multiple-phase tablets
30 where, for example, only one phase contains bleaching agent, only this
CA 02300016 2000-02-25
31
phase need satisfy the hygroscopicity criteria. Accordingly, the term
"tablet" can be replaced by "phase", so that the present invention also
relates to multiple-phase tablets where only one phase contains bleaching
agent and this phase has hygroscopicity values above 2 g per 10 g of the
phase weight, which results in excellent bleach stability. Analogously, the
present invention also relates to multiple-phase tablets where only one
phase contains enzymes and this phase has hygroscopicity values below 2
g per 10 g of the phase weight. Excellent enzyme stability is achieved in
this way.
According to the invention, the individual phases of the tablet may
assume various three-dimensional forms. The simplest embodiment are
two-layer or multiple-layer tablets, each layer of the tablet representing a
phase. However, it is also possible in accordance with the invention to
produce multiple-phase tablets in which individual phases assume the form
of incorporations in (another) other phase(s). Besides so-called ring/core
tablets, shell tablets or combinations of the embodiments mentioned are
possible. Examples of multiple-phase tablets can be found in the drawings
of EP-A-0 055 100 (Jeyes) which describes lavatory cleaning blocks. The
most widespread form of multiphase tablets is the two-layer or multiple-
layer tablet. According to the invention, therefore, the phases of the tablet
preferably assume the form of layers.
In multiple-phase tablets, the above-mentioned total contents of
bleaching agent and enzymes in the tablet are based on the weight of the
individual phase. Preferred multiple-phase detergent tablets are those
where the bleach-containing phase contains 5 to 50% by weight, preferably
7.5 to 40% by weight and more preferably 10 to 30% by weight, based on
the phase, of bleaching agent while the enzyme-containing phase contains
1 to 20% by weight, preferably 1.5 to 15% by weight and more preferably 2
to 10% by weight, based on the phase, of enzymes.
To produce the single-phase tablets according to the invention, the
CA 02300016 2000-02-25
32
premix is compacted between two punches in a die to form a solid
compactate. This process, which is referred to in short hereinafter as
tabletting, comprises four phases, namely metering, compacting (elastic
deformation), plastic deformation and ejection.
The premix is first introduced into the die, the filling level and hence
the weight and shape of the tablet formed being determined by the position
of the lower punch and the shape of the die. Uniform metering, even at
high tablet throughputs, is preferably achieved by volumetric metering of
the premix. As the tabletting process continues, the top punch comes into
contact with the premix and continues descending towards the bottom
punch. During this compaction phase, the particles of the premix are
pressed closer together, the void volume in the filling between the punches
continuously diminishing. The plastic deformation phase in which the
particles coalesce and form the tablet begins from a certain position of the
top punch (and hence from a certain pressure on the premix). Depending
on the physical properties of the premix, its constituent particles are also
partly crushed, the premix sintering at even higher pressures. As the
tabletting rate increases, i.e. at high throughputs, the elastic deformation
phase becomes increasingly shorter so that the tablets formed can have
more or less large voids. In the final step of the tabletting process, the
tablet is forced from the die by the bottom punch and carried away by
following conveyors. At this stage, only the weight of the tablet is
definitively established because the tablets can still change shape and size
as a result of physical processes (re-elongation, crystallographic effects,
cooling, etc.).
The tabletting process is carried out in commercially available tablet
presses which, in principle, may be equipped with single or double
punches. In the latter case, not only is the top punch used to build up
pressure, the bottom punch also moves towards the top punch during the
tabletting process while the top punch presses downwards. For small
CA 02300016 2000-02-25
33
production volumes, it is preferred to use eccentric tablet presses in which
the punches) is/are fixed to an eccentric disk which, in turn, is mounted on
a shaft rotating at a certain speed. The movement of these punches is
comparable with the operation of a conventional four-stroke engine.
Tabletting can be carried out with a top punch and a bottom punch,
although several punches can also be fixed to a single eccentric disk, in
which case the number of die bores is correspondingly increased. The
throughputs of eccentric presses vary according to type from a few hundred
to at most 3,000 tablets per hour.
For larger throughputs, rotary tablet presses are generally used. In
rotary tablet presses, a relatively large number of dies is arranged in a
circle on a so-called die table. The number of dies varies - according to
model - between 6 and 55, although even larger dies are commercially
available. Top and bottom punches are associated with each die on the
die table, the tabletting pressures again being actively built up not only by
the top punch or bottom punch, but also by both punches. The die table
and the punches move about a common vertical axis, the punches being
brought into the filling, compaction, plastic deformation and ejection
positions by means of curved guide rails. At those places where the
punches have to be raised or lowered to a particularly significant extent
(filling, compaction, ejection), these curved guide rails are supported by
additional push-down members, pull-down rails and ejection paths. The die
is filled from a rigidly arranged feed unit, the so-called filling shoe, which
is
connected to a storage container for the premix. The pressure applied to
the premix can be individually adjusted through the tools for the top and
bottom punches, pressure being built up by the rolling of the punch shank
heads past adjustable pressure rollers.
To increase throughput, rotary presses can also be equipped with
two filling shoes so that only half a circle has to be negotiated to produce a
tablet. To produce two-layer or multiple-layer tablets, several filling shoes
CA 02300016 2000-02-25
34
are arranged one behind the other without the lightly compacted first layer
being ejected before further filling. Given suitable process control, shell
and bull's-eye tablets - which have a structure resembling an onion skin -
can also be produced in this way. In the case of bull's-eye tablets, the
upper surface of the core or rather the core layers is not covered and thus
remains visible. Rotary tablet presses can also be equipped with single or
multiple punches so that, for example, an outer circle with 50 bores and an
inner circle with 35 bores can be simultaneously used for tabletting.
Modern rotary tablet presses have throughputs of more than one million
tablets per hour.
Tabletting machines suitable for the purposes of the invention can
be obtained, for example, from the following companies: Apparatebau
Holzwarth GbR, Asperg, Wilhelm Fette GmbH, Schwarzenbek, Hofer
GmbH, Weil, KILIAN, Cologne, KOMAGE, Kell am See, KORSCH Pressen
GmbH, Berlin, Mapag Maschinenbau AG, Bern (Switzerland) and Courtoy
N.V., Halle (BE/LU). One example of a particularly suitable tabletting
machine is the model HPF 630 hydraulic double-pressure press
manufactured by LAEIS, D.
The tablets can be made in certain shapes and certain sizes.
Suitable shapes are virtually any easy-to-handle shapes, for example
slabs, bars, cubes, squares and corresponding shapes with flat sides and,
in particular, cylindrical forms of circular or oval cross-section. This last
embodiment encompasses shapes from tablets to compact cylinders with a
height-to-diameter ratio of more than 1.
The portioned pressings may be formed as separate individual
elements which correspond to a predetermined dose of the detergent.
However, it is also possible to form pressings which combine several such
units in a single pressing, smaller portioned units being easy to break off in
particular through the provision of predetermined weak spots. For the use
of laundry detergents in machines of the standard European type with
CA 02300016 2000-02-25
horizontally arranged mechanics, it can be of advantage to produce the
portioned pressings as cylindrical or square tablets, preferably with a
diameter-to-height ratio of about 0.5:2 to 2:0.5. Commercially available
hydraulic presses, eccentric presses and rotary presses are particularly
5 suitable for the production of pressings such as these.
Another preferred tablet which can be produced has a plate-like or
slab-like structure with alternately thick long segments and thin short
segments, so that individual segments can be broken off from this "bar" at
the predetermined weak spots, which the short thin segments represent,
10 and introduced into the machine. This "bar" principle can also be
embodied in other geometric forms, for example vertical triangles which are
only joined to one another at one of their longitudinal sides.
In another possible embodiment, however, the various components
are not compressed to form a single tablet, instead the tablets obtained
15 comprise several layers, i.e. at least two layers. These various layers may
have different dissolving rates. This can provide the tablets with favorable
performance properties. If, for example, the tablets contain components
which adversely affect one another, one component may be integrated in
the more quickly dissolving layer while the other component may be
20 incorporated in a more slowly dissolving layer so that the first component
can already have reacted off by the time the second component dissolves.
The various layers of the tablets can be arranged in the form of a stack, in
which case the inner layers) dissolve at the edges of the tablet before the
outer layers have completely dissolved. Alternatively, however, the inner
25 layers) may also be completely surrounded by the layers lying further to
the outside which prevents constituents of the inner layers) from dissolving
prematurely.
Similar effects can also be obtained by coating individual constitu-
ents of the detergent composition to be compressed or the tablet as a
30 whole. To this end, the tablets to be coated may be sprayed, for example,
CA 02300016 2000-02-25
36
with aqueous solutions or emulsions or a coating may be obtained by the
process known as melt coating.
After pressing, the laundry and dishwasher detergent tablets have
high stability. The fracture resistance of cylindrical tablets can be
determined via the diametral fracture stress. This in turn can be
determined in accordance with the following equation:
2P
BDt
where ~ represents the diametral fracture stress (DFS) in Pa, P is the force
in N which leads to the pressure applied to the tablet that results in
fracture
thereof, D is the diameter of the tablet in meters and t is its height.
Examples
Dishwasher tablets were produced by tabletting premixes of different
composition. The raw materials used for this purpose and the
experimentally determined hygroscopicity values of the raw materials are
set out in Table 1. Table 2 compares calculated hygroscopicity values,
experimentally determined tablet hygroscopicities and the active oxygen
retention of bleach-containing tablets. Table 3 compares calculated
hygroscopicities, experimentally determined tablet hygroscopicities and the
enzyme retention of enzyme-containing tablets.
Table 1
Hygroscopicity values of the raw materials used [g per 10 g after 1 weeks
at 30°C/80% relative humidity]
Ingredient Hygroscopicity
Trisodium polyphosphate 1.97
CA 02300016 2000-02-25
37
Trisodium polyphosphate, fine 2.24
Sodium carbonate 3.90
Sodium hydrogen carbonate 0.00
Sodium silicate 5.80
Trisodium citrate dehydrate 0.01
Enzyme granules I 0.56
Enzyme granules II 0.25
TAED granules 0.40
Sodium perborate monohydrate 3.33
Table 2
Hygroscopicity values of bleach-containing detergent tablets
Tablet E1 E2 E3 V
Hygroscopicity of the tablet*2.1 2.9 1.8 1.7
Hygroscopicity of the premix**5.8 8.0 3.6 2.3
Active oxygen retention [%] 84 87 77 62
Table 3
Hygroscopicity values of enzyme-containing detergent tablets
Tablet E1 E2 E3 V
Hygroscopicity of the tablet*1.8 0.9 1.8 2.4
Hygroscopicity of the premix**4.7 2.0 4.3 7.4
Enzyme retention [%] 81.5 86.5 78.9 69.2
* experimentally determined water absorption in g per 10 g of tablet
after storage for 1 week at 30°C/80% relative humidity
CA 02300016 2000-02-25
38
** sum of the hygroscopicity values of the raw materials (Table 1 ) each
multiplied by their percentage content
