Note: Descriptions are shown in the official language in which they were submitted.
- CA 02298966 2000-02-18
Color-stable Detergent Tablets
Field of the Invention
This invention relates to colored detergent tablets. More,
particularly, the present invention relates to detergent tablets intended for
use in dishwashing machines.
Background of the Invention
Machine dishwashing detergents are widely described in the prior
art. They normally contain one or more builders, bleaching agents, bleach
activators, corrosion inhibitors and surfactants. In order to provide the
consumer with a typical and unmistakable product, such detergents are
normally perfumed and colored. The dyes used have to meet various
requirements. They are expected to color the detergent permanently and
in a visually noticeable manner, even in low concentrations, and should
neither fade nor discolor, even after prolonged storage at elevated
temperature. To this end, the dyes used have to be chemically inert to the
partly aggressive ingredients (for example bleaching agents, alkalinity
sources) and must not decompose either themselves or other ingredients.
Since commercially available detergent tablets are often two-colored for
aesthetic reasons, no fading of the colored phase nor any migration of dye
into lighter or uncolored areas should occur at the phase boundary
between areas of different color.
The dyes are expected to satisfy stringent requirements in this
regard. Although the detergents have to be contrastingly colored, the dye
must not color either the dishwashing machine or the tableware to be
cleaned, even in the event of prolonged use of one and the same
detergent. Accordingly, the dyes must not have any pronounced
substantivity towards metal or plastic surfaces. In addition, the dyes must
be completely removed from the dishwashing machine in the rinse cycle
and, after drainage, should not leave any films or colored lime stains
behind on the tableware or in the machine. In addition, since the tableware
_ CA 02298966 2000-02-18
2
is subsequently used for the preparation and storage of food, the dyes
have to be toxicologically safe.
Earlier German patent application DE 198 21 695.5 (Henkel KGaA)
describes the use of special dyes in detergents with a view to overcoming
the problems mentioned above. The dyes mentioned in this document are
also suitable for coloring laundry and dishwasher detergent tablets or
individual areas of dishwasher tablets.
In tablets, the contact between dye and other dye-destabilizing
ingredients (particularly bleaching agents) is so intimate that changes in
color can occur in the event of prolonged storage, spoiling the appearance
of the tablet. Where dyes are used above all in phosphate-free
formulations where citrates are present as builders, the partly inadequate
stability of the dyes to bleaching agents has proved to be a serious
disadvantage. It has also been found in this connection that the logical
separation of bleaching agent and dye into different areas of the tablet is
not a solution in itself. Even if this measure is taken, fading and dye
migration problems still occur at the phase boundary, leading to tablets of
unacceptable appearance.
Now, the problem addressed by the present invention was to enable
dyes unstable to bleaching agents to be used even in laundry and
dishwasher detergent tablets without any of the disadvantages mentioned
above having to be accepted. The above-mentioned requirement profile
would be fully satisfied even - and above all - in phosphate-free and/or
citrate-containing formulations.
Description of the Invention
It has now been found that the addition of paraffin to the tablet or to
that area of the tablet which contains the dye unstable to bleaching agents
solves the problems mentioned above.
The present invention relates to laundry and dishwasher detergent
tablets of compacted particulate detergent containing builders, bleaching
CA 02298966 2000-02-18
3
agents and other typical detergent ingredients, characterized in that they
contain at least one dye unstable to bleaching agents and in that the areas
of the tablet containing the dye unstable to bleaching agents additionally
contains paraffin.
Besides the constituents builder and bleaching agent and the dye
unstable to bleaching agents, laundry and dishwasher detergent tablets
according to the invention contain paraffin. Paraffin in the context of the
present invention is the term used for a colorless, odorless and tasteless
mixture of purified, saturated aliphatic hydrocarbons (paraffins). These
alkane mixtures are commercially available and may be used in
accordance with the present invention in various supply forms - from low-
viscosity through relatively high-viscosity to paste-form or solid paraffin.
Low-viscosity paraffins normally have densities of 0.81 to 0.875 gcrri 3 and
viscosities of 25 to 80 mPas whereas viscous paraffins have densities of
0.827 to 089 gcm-3 and viscosities of 110 to 230 mPas. Industrially, the
liquid paraffins are often classed as mineral oils and are collectively
referred to as paraffin oil or as white oil, the density of such products
normally being at least 0.88 gcm-3 and their boiling point >360°C.
Semisolid paraffins with melting points of 45-65°C are known by
such names as soft paraffin while those with densities of 0.82 to 0.88 gcm-3
and melting points of 38 to 60°C and boiling points of >300°C
are known by
such names as petrolatum; a well-known trade mark for paraffins of this
type is Vaseline. Hard paraffin (Paraffinum solidum) - a solid crystalline
mass with a solidification temperature of 50 to 62°C - is also known.
According to the present invention, paraffin oils are particularly
preferred. Preferred laundry and dishwasher detergent tablets according to
the invention contain 0.1 to 5% by weight, preferably 0.25 to 4% by weight
and more preferably 0.5 to 3% by weight of paraffin oil and/or paraffin wax,
preferably low-viscosity paraffin oil.
The other ingredients compulsorily present in the tablets according
CA 02298966 2000-02-18
4
to the invention are described in the following:
The builder present in the laundry and dishwasher detergent tablets
according to the invention may be selected from any of the builders
typically present in detergents, i.e. in particular zeolites, silicates,
carbonates, organic cobuilders and also the phosphates.
Suitable crystalline layered sodium silicates correspond to the
general formula NaMSiX02x+~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 layered silicates such as these are described,
for example, in European patent application EP-A-0 164 514. Preferred
crystalline layered silicates corresponding to the above formula are those in
which M is sodium and x assumes the value 2 or 3. Both Vii- and 8-sodium
disilicates Na2Si205y H20 are particularly preferred, (i-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 (NaZO: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
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
interpreted to mean that the products have microcrystalline regions
CA 02298966 2000-02-18
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
5 German patent application DE-A-44 00 024. Compacted amorphous
silicates, compounded amorphous silicates and overdried X-ray-amorphous
silicates are particularly preferred.
The finely crystalline, synthetic zeolite containing bound water used
in accordance with the invention is preferably zeolite A and/or zeolite P.
Zeolite MAP~ (Crosfield) is a particularly preferred P-type zeolite.
However, zeolite X and mixtures of A, X and/or P are also suitable.
According to the invention, it is also possible to use, for example, a co-
crystallizate of zeolite X and zeolite A (ca. 80% by weight zeolite X) which
is marketed by CONDEA Augusta S.p.A. under the name of VEGOBOND
AX~ and which may be described by the following formula:
nNa20 ~ (1-n)K20 ' AI2O3 ~ (2 - 2.5)Si02 ~ (3.5 - 5.5) H20.
The zeolite may be used both as a builder in a granular compound and for
"powdering" the entire mixture to be tabletted, both these options normally
being used to incorporate the zeolite in the premix. Suitable zeolites have
a mean particle size of less than 10 ~m (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.
Useful organic builders are, for example, the polycarboxylic acids
usable, for example, in the form of their sodium salts, such as citric acid,
CA 02298966 2000-02-18
6
adipic acid, succinic acid, glutaric acid, tartaric acid, sugar acids, amino-
carboxylic acids, nitrilotriacetic acid (NTA), providing their 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.
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.
Water-soluble builders are preferably used in dishwasher tablets
according to the invention because, in general, they tend less to form
insoluble residues on tableware and hard surfaces. Typical builders which
may be present in dishwasher tablets according to the invention in
quantities of 10 to 90% by weight, based on the premix to be tabletted, are
the low molecular weight polycarboxylic acids and salts thereof, the homo-
polymeric and copolymeric polycarboxylic acids and salts thereof, the car-
bonates, phosphates and silicates. 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 for the production of dishwasher
tablets. 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.
According to the invention, preferred detergent tablets 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
CA 02298966 2000-02-18
7
builders from the group of phosphates, more particularly pentasodium
tripolyphosphate, 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.
The incorporation of paraffin in the tablet or in that part of the tablet
where the dye unstable to bleaches is present in accordance with the
invention has particular advantages when the builder system contains
citrates and is free from phosphates. In tablets such as these, the
problems solved by the invention would otherwise come very clearly to
light. According to the invention, preferred detergent tablets contain no
phosphates.
As mentioned above, it is of advantage to use citrate-carbonate
builder systems in dishwasher tablets. Accordingly, preferred detergent
tablets are characterized in that they contain as builder 5 to 40% by weight,
preferably 10 to 35% by weight and more preferably 15 to 30% by weight of
one or more alkali metal citrates, preferably trisodium citrate dehydrate, and
5 to 50% by weight, preferably 10 to 45% by weight and more preferably 15
to 40% by weight of one or more alkali metal carbonates and/or hydrogen
carbonates, preferably sodium hydrogen carbonate.
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-
drates and H202-yielding peracidic salts or peracids, such as
perbenzoates, peroxophthalates, diperazelaic acid, phthaloiminoperacid or
diperdodecane dioic acid. Even where bleaching agents are used, there is
no need for surfactants and/or builders so that pure bleaching tablets can
be produced. If such bleaching tablets are to be used for washing laundry,
CA 02298966 2000-02-18
sodium percarbonate is preferably used, irrespective of which other
ingredients are present in the tablets. If detergent or bleaching 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 [phthaoiminoperoxyhexanoic 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 tablets for dishwashing machines
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, tribromo
isocyanuric acid, dibromoisocyanuric 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.
According to the invention, preferred detergent tablets are
characterized in that the bleaching agent is selected from the groups of
oxygen bleaching agents, more particularly sodium perborate
monohydrate, sodium perborate tetrahydrate and sodium percarbonate,
CA 02298966 2000-02-18
9
and/or halogen bleaching aents, more particularly chlorine bleaching
agents, of which trichlorocyanuric acids, dichloro- and
monochlorocyanurates and hypochlorites are particularly preferred.
Besides builder(s), bleaching agents) and paraffin, the detergent
tablets according to the invention (or parts thereof) contain one or more
dyes) unstable to bleaching agents as a fourth key constituent.
Corresponding dyes suitable for coloring detergents are dyes
soluble in solvents and/or binders. In view of the structural diversity of
these dyes (for example azo, azine, anthraquinone, acridine, cyanine,
oxazine, polymethine, thiazine, triarylmethane dyes, etc.), several thousand
different dyes are known, of which around 5,000 are commercially available
and only around 500 are produced in industrial quantities. The dyes are
systematically categorized not only according to their structure, but also
under the so-called Colour Index with its number system (C.I. xxxx) or
word/number system (Acid Red xxx). In the case of dyes which have been
broadly adopted, the made-up names and trade names registered as trade
marks may also be used for characterization.
Dyes used in laundry detergent and dishwasher tablets should have
high stability in storage, should not be affected by the other ingredients of
the detergent or by light and should not show pronounced substantivity
towards textile fibers or tableware so as not to color them. In dishwasher
tablets, the dyes mentioned in the prior art literature cited at the beginning
-
whose stability to bleaching agents has been improved in accordance with
the invention - have proved to be suitable dyes. Specific examples of
these dyes are Ponceau 4R (CAS No. 2611-82-7, C.I. 16255), Allura Red
40 (CAS No. 25956-17-6, CI 16035), Aluminium Rot RLW (CI Mordant
Red 83), Supranol~ Rot GW (CAS No. 61901-44-8), Basantol~ Rot 310
(CAS No. 61951-36-8), Basacid~ Grun 970 (CAS-No. 19381-50-1),
Supranol~ Grun 6 GW (anthraquinone dye preparation containing Acid
Green 81), Supranol~ Griin BW (anthraquinone dye preparation
CA 02298966 2000-02-18
containing Acid Green 84), Ultramarinblau-6394 (CAS No. 57455-37-5, CI
77007), Acid Yellow 17 (CAS No. 6359-98-4, CI 18965) and Acid Yellow
23 (CAS No. 1934-21-0, CI 19140).
The quantities in which the dyes are used in the laundry and
5 dishwashing detergent tablets according to the invention may vary
according to the required color impression and the particular application
envisaged. Preferred laundry and dishwashing detergent tablets according
to the invention contain the dyes) unstable to bleaching agents in
quantities of 0.01 to 1 % by weight, preferably 0.02 to 0.5% by weight and
10 more preferably 0.05 to 0.25% by weight, based on the tablet.
Besides the ingredients mentioned, the laundry and dishwashing
detergent tablets according to the invention may contain other ingredients
emanating in particular from the groups of bleach activators, disintegration
aids, surfactants, enzymes, silver protectors, perfumes, polymers, pH
regulators, fluorescers, foam inhibitors, redeposition inhibitors, optical
brighteners, discoloration inhibitors, dye transfer inhibitors and corrosion
inhibitors and mixtures thereof.
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 in the detergent tablets. 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 alkylene-
diamines, more particularly tetraacetyl ethylenediamine (TAED), acylated
triazine derivatives, more particularly 1,5-diacetyl-2,4-dioxohexahydro-
1,3,5-triazine (DADHT), acylated glycolurils, more particularly tetraacetyl
glycoluril (TAGU), N-acylimides, more particularly N-nonanoyl succinimide
- CA 02298966 2000-02-18
11
(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,
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.
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
- CA 02298966 2000-02-18
12
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,
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
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
cellulose has the formal empirical composition (C6H~o05)~ 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
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
- CA 02298966 2000-02-18
13
hydrogen atoms have been substituted. However, celluloses in which the
hydroxy groups have been replaced by functional groups that are not
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
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
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 arm 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
CA 02298966 2000-02-18
14
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.
Besides the builders mentioned above, the premix may also contain
the detersive substances already mentioned which are particularly
important ingredients for laundry detergent tablets. Depending on the
tablet to be produced, different anwers are possible to the questions of
whether to use surfactants and, if so, which surfactants. Normally, laundry
detergent tablets may contain various surfactants from the groups of
anionic, nonionic, cationic and amphoteric surfactants whereas dishwasher
tablets preferably contain only low-foaming surfactants and water softening
tablets and bleach tablets are free from surfactants. So far as the
incorporation of the surfactants in the premix to be tabletted is concerned,
there are no basic requirements to restrict the freedom of formulation.
Suitable anionic surfactants are, for example, those of the sulfonate
and sulfate type. Suitable surfactants of the sulfonate type are preferably
C9_~3 alkyl benzenesulfonates, olefin sulfonates, i.e. mixtures of alkene and
hydroxyalkane sulfonates, and the disulfonates obtained, for example, from
C~2-~s 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~2_~$ alkanes, for example by
sulfochlorination or sulfoxidation and subsequent hydrolysis or
neutralization. The esters of a-sulfofatty acids (ester sulfonates), for
example the a-sulfonated methyl esters of hydrogenated coconut oil, palm
kernel oil or tallow fatty acids, are also suitable.
CA 02298966 2000-02-18
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
5 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.
10 Preferred alk(en)yl sulfates are the alkali metal salts and, in
particular, the sodium salts of the sulfuric acid semiesters of C~Z_~8 fatty
alcohols, for example cocofatty alcohol, tallow fatty alcohol, lauryl,
myristyl,
cetyl or stearyl alcohol, or C~0.2o oxoalcohols and the corresponding
semiesters of secondary alcohols with the same chain length. Other
15 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_,6 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
Cø> > alcohols containing on average 3.5 moles of ethylene oxide (EO) or
C~2_~$ 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
example in quantities of 1 to 5% by weight, in dishwashing detergents.
Other suitable anionic surfactants are the salts of alkyl sulfosuccinic
~
CA 02298966 2000-02-18
16
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 C$_~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 oil, palm kernel oil 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.
According to the invention, preferred detergents tablets are those in
which the surfactant granules contain 5 to 45% by weight, preferably 10 to
40% by weight and more preferably 15 to 35% by weight of anionic
surfactants, based on the weight of the surfactant granules.
So far as the choice of anionic surfactants is concerned, there are
no basic requirements to restrict the freedom of formulation. However,
preferred surfactant granules do have a soap content in excess of 0.2% by
weight, based on the total weight of the detergent tablets. Preferred
anionic surfactants are alkyl benzenesulfonates and fatty alcohol sulfates,
' CA 02298966 2000-02-18
17
preferred 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 composition.
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 oil, palm oil, tallow fatty 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, C9_» 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
atoms in the alkyl chain, more especially the fatty acid methyl esters which
are described, for example, in Japanese patent application JP 581217598
' CA 02298966 2000-02-18
18
or which are preferably produced by the process described in International
patent application WO-A-90113533.
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
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-
alkyl group, are preferably used.
The detergent tablets according to the invention 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
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):
R'
R-CO-N-[Z] (I)
~
CA 02298966 2000-02-18
19
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
example in accordance with the teaching of International patent application
WO-A-95/07331.
In principle, any surfactants may also be used as surfactants in the
" CA 02298966 2000-02-18
production of dishwasher tablets. However, the nonionic surfactants
described above, above all low-foaming nonionic surfactants, are
preferably used for this purpose. Alkoxylated alcohols, especially
ethoxylated and/or propoxylated alcohols, are particularly preferred.
5 Alkoxylated alcohols are generally understood by the expert to be the
reaction products of alkylene oxide, preferably ethylene oxide, with
alcohols, the relatively long-chain alcohols (C~o to CAB, preferably between
C~Z and Cps such as, for example, C», C~2, C~3, C~4, C~5, Cps, C~~ and C~8
alcohols) being preferred for the purposes of the present invention. In
10 general, a complex mixture of addition products differing in their degree
of
ethoxylation is formed from n moles of ethylene oxide and 1 mole of
alcohol, depending on the reaction conditions. Another embodiment is
characterized by the use of mixtures of alkylene oxides, preferably a
mixture of ethylene oxide and propylene oxide. If desired, "end-capped"
15 alcohol ethoxylates, which may also be used in accordance with the
invention, may also be obtained by etherification with short-chain alkyl
groups, preferably butyl groups, in a concluding step. According to the
invention, highly ethoxylated fatty alcohols or mixtures thereof with end
capped fatty alcohol ethoxylates are particularly preferred for the purposes
20 of the invention.
Suitable enzymes for dishwasher tablets are, in particular, those
from the classes of hydrolases, such as proteases, esterases, lipases or
lipolytic enzymes, amylases, cellulases or other 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
- CA 02298966 2000-02-18
21
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, amylase and lipase or lipolytic enzymes or
protease, lipase or lipolytic enzymes, 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 in the tablets according to the invention may be, for example, from
about 0.1 to 5% by weight and is preferably from 0.5 to about 4.5% by
weight.
In laundry detergent tablets, cellulases may also be used in addition
to the enzymes mentioned above. Cellulases and other glycosyl
hydrolases can contribute towards color retention and towards increasing
fabric softness by removing pilling and microfibrils. Preferred cellulases are
cellobiohydrolases, endoglucanases and ~i-glucosidases, which are also
known as cellobiases, and mixtures thereof. Since the various cellulase
types differ in their CMCase and avicelase activities, the desired activities
can be established by mixing the cellulases in the appropriate ratios.
If dishwasher tablets according to the invention are to be produced,
they may contain corrosion inhibitors to protect the tableware or the
machine itself, silver protectors being particularly important for dishwashing
machines. Known corrosion inhibitors may be used. 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. In addition, dishwashing
' CA 02298966 2000-02-18
22
formulations often contain corrosion inhibitors containing active chlorine
which are capable of distinctly reducing the corrosion of silver surfaces.
Chlorine-free dishwashing detergents contain in particular oxygen- and
nitrogen-containing organic redox-active compounds, such as dihydric and
trihydric phenols, for example hydroquinone, pyrocatechol, hydroxy-
hydroquinone, gallic acid, phloroglucinol, pyrogallol and derivatives of
these compounds. 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, 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
to b lewa re.
Preferred laundry and dishwasher detergent tablets according to the
invention additionally contain at least one silver protector selected from the
group of triazoles, benzotriazoles, bisbenztotriazoles, aminotriazoles
alkylamiotriazoles, preferably benzotriazole and/or alkylaminotriazole.
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-
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
CA 02298966 2000-02-18
23
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.
If laundry detergent tablets are to be produced, the premix to be
tabletted 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'-disulfonic acid or compounds of similar composition
which contain a diethanolamino group, a methylamino group, an anilino
group or a 2-methoxyethylamino group instead of the morpholino group.
Brighteners of the substituted diphenyl styryl type, for example alkali metal
salts of 4,4'-bis-(2-sulfostyryl)-Biphenyl, 4,4'-bis-(4-chloro-3-sulfostyryl)-
diphenyl or 4-(4-chlorostyryl)-4'-(2-sulfostyryl)-Biphenyl, may also be
present. Mixtures of the brighteners mentioned above may also be used.
Perfumes may be added to the 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 fragrances include
individual fragrance compounds, for example synthetic products of the
ester, ether, aldehyde, ketone, alcohol and hydrocarbon type. Fragrance
compounds of the ester type are, for example, benzyl acetate, phenoxy-
ethyl isobutyrate, p-tert.butyl cyclohexyl acetate, linalyl acetate, dimethyl
benzyl carbinyl acetate, phenyl ethyl acetate, linalyl 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, citronellyloxy-
acetaldehyde, cyclamen aldehyde, hydroxycitronellal, lilial and bourgeonal;
the ketones include, for example, the ionones, a-isomethyl ionone and
CA 02298966 2000-02-18
24
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 fragrances which together produce an attractive
fragrance note are preferably used. Perfume oils such as these may also
contain natural fragrance 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 perfumes may be directly incorporated in the premix, 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.
To produce the tablets according to the invention, the 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
' CA 02298966 2000-02-18
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
5 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
10 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.).
15 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
20 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,
25 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
~
CA 02298966 2000-02-18
26
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
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
~
CA 02298966 2000-02-18
27
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
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
suitable for the production of pressings such as these.
The three-dimensional form of another embodiment of the tablets
according to the invention is adapted in its dimensions to the dispensing
compartment of commercially available domestic washing machines, so
that the tablets can be introduced directly, i.e. without a dosing aid, into
the
dispensing compartment where they dissolve on contact with water.
However, it is of course readily possible - and preferred in accordance with
' CA 02298966 2000-02-18
28
the present invention - to use the detergent tablets in conjunction with a
dosing aid.
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,
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
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
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
layers) may also be completely surrounded by the layers lying further to
the outside which prevents constituents of the inner layers) from dissolving
prematurely.
In another preferred embodiment of the invention, a tablet consists
of at least three layers, i.e. two outer layers and at least one inner layer,
a
peroxy bleaching agent being present in at least one of the inner layers
whereas, in the case of the stack-like tablet, the two cover layers and, in
the case of the envelope-like tablet, the outermost layers are free from
peroxy bleaching agent. In another possible embodiment, peroxy
' CA 02298966 2000-02-18
29
bleaching agent and any bleach activators present and/or enzymes may be
spatially separated from one another in one and the same tablet. Multilayer
tablets such as these have the advantage that they can be used not only
via a dispensing compartment or via a dosing unit which is added to the
wash liquor, instead it is also possible in cases such as these to introduce
the tablet into the machine in direct contact with the fabrics without any
danger of spotting by bleaching agent or the like.
Similar effects can also be obtained by coating individual constitu
ents of the detergent composition to be compressed or the tablet as a
whole. To this end, the tablets to be coated may be sprayed, for example,
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
a-
~Dt
where a 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.
As mentioned above, tablets according to the invention comprising
several phases, preferably several layers, may also be produced.
Accordingly, the present invention also relates to multiphase laundry and
dishwasher detergent tablets of compacted particulate detergent containing
builders, bleaching agents, at least one dye unstable to bleaches and other
typical ingredients, characterized in that the bleaching agents) and/or the
dyes) unstable to bleaching agents are present in separate phases and in
a CA 02298966 2000-02-18
that the phase containing the dye unstable to bleaching agents additionally
contains paraffin. As already mentioned, multiphase detergent tablets in
which the phases of the tablet are in the form of layers are preferred.
The above-mentioned ingredients and quantity ranges in which they
5 are used are also preferred for multiphase tablets. So far as the
ingredients bleaching agent and dye are concerned, preferred multiphase
laundry and dishwasher detergent tablets are those in which 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
10 bleaching agent and the dye-containing phase contains 0.01 to 2% by
weight, preferably 0.05 to 15% by weight and more preferably 0.1 to 1.0%
by weight, based on the phase, of dye.
Embodiments of the present invention are described in the following
Examples which are not to be construed as limiting.
Examples
Two-layer dishwasher tablets (one third upper phase, two thirds
lower phase) were produced by tabletting various premixes. First, the
particular premix for the lower phase was introduced into the die of a
commercial tablet press (Korsch TRP 700) and precompressed, after which
the premix for the upper phase was introduced and the tabletting process
completed.
The tablets E according to the invention differ from the comparison
tablets C in that the colored layer (upper phase) additionally contains
paraffin. The composition of the premixes to be compressed and hence
the composition of the tablets is shown in the following Table:
CA 02298966 2000-02-18
31
E V
Upper Lower Upper Lower
phase phase phase phase
Sodium carbonate 19.0 - 19.0 -
Sodium hydrogen carbonate 40.0 20.0 43.0 20.0
Trisodium citrate dehydrate24.0 55.0 24.0 55.0
Enzyme granules 13.4 - 13.4 -
Perfume 0.4 - 0.4 -
Dye* 0.2 - 0.2 -
Paraffin oil 3.0 - - -
Sodium perborate monohydrate- 15.0 - 15.0
Tetraacetyl ethylenediamine- 6.0 - 6.0
C~2 Fatty alcohol + 3E0 - 4.0 - 4.0
* Ponceau 4R (CI 16255):
7-Hydroxy-8-[(4-sulfo-1-naphthalenyl)azo]-1,3-naphthalenedisulfonic acid
trisodium salt
The tablets were visually evaluated immediately after production and
after storage for one week. The results are set out in the following Table.
CA 02298966 2000-02-18
32
Tablet E C
Color of upper phaseBright red Bright red
after production
Color of upper phaseBright red, no changePale pink, lightened
after 1 week's storage
Phase boundary afterClean straight lineClean straight line
production
Phase boundary afterNo change Irregular: coloring
1 of
week's storage lower phase, fading
of
upper phase
Stability in storageGood Poor
The use of the paraffin oil in the colored layer leads to better color
stability and greater color brightness.
