Note: Descriptions are shown in the official language in which they were submitted.
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Detergent Tablets Containing Binder Compound
Field of the Invention
This invention relates generally to compact shaped bodies having
detersive properties. Such 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 laundry detergent tablets which are used for
washing laundry in domestic washing machines and which are referred to
in short as detergent tablets.
Background of the Invention
Detergent tablets are widely described in the prior-art literature and
are enjoying increasing popularity among consumers because they are
easy to dose. Tabletted detergents have a number of advantages over
powder-form detergents: they are easier to dose and handle and, by virtue
of their compact structure, have advantages in regard to storage and
transportation. As a result, detergent shaped bodies are also
comprehensively described in the patent literature. One problem which
repeatedly arises in the use of detergent tablets is the inadequate
disintegrating and dissolving rate of the tablets under in-use conditions.
Since sufficiently stable, i.e. dimensionally stable and fracture-resistant,
tablets can only be produced by applying relatively high pressures, the
ingredients of the tablet are heavily compacted so that disintegration of the
tablet in the wash liquor is delayed which results in excessively slow
release of the active substances in the washing process. The delayed
disintegration of the tablets has the further disadvantage that typical
detergent tablets cannot be flushed into the washing process from the
dispensing compartment of domestic washing machines because the
tablets do not disintegrate sufficiently quickly into secondary particles
which
are small enough to be flushed from the dispensing compartment into the
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2
drum of the washing machine. Another problem which occurs with
detergent tablets in particular lies in the friability of the tablets and
their
often inadequate resistance to abrasion. Thus, although sufficiently
fracture-resistant, i.e. hard, detergent tablets can be produced, they are
often not strong enough to withstand the loads encountered during
packaging, transportation and handling, i.e. impact and friction effects, so
that broken edges and signs of abrasion spoil the appearance of the tablet
or even lead to the complete destruction of its structure.
Many solutions have been developed in the prior art to overcome the
dichotomy between hardness, i.e. transportation and handling stability, and
easy disintegration of the tablets. One solution known in particular from the
field of pharmacy and extended to detergent tablets is to incorporate
certain disintegration aids which facilitate the access of water and which
swell on contact with water and effervesce or otherwise disintegrate. Other
solutions proposed in the patent literature are based on the compression of
premixes of certain particle sizes, the separation of individual ingredients
from certain other ingredients and the coating of individual ingredients or
the entire tablet with binders.
Thus, EP 687 464 (Allphamed Arzneimittel-Gesellschaft) describes
effervescent tablets which consist of at least one active principle or a
combination of active principles, at least one binder, optionally carriers
such as flavors, dyes, perfumes, plasticizers, bleaching agents and
effervescent additives, the binders) used being propylene glycol or
glycerol, preferably in quantities of 0.004 to 2.5% by weight. Processes for
producing these effervescent tablets are also claimed. According to the
disclosure of this document, it is also possible through the teaching of the
invention to produce an effervescent detergent tablet without the binder
used leading to a loss of carbon dioxide from the effervescent additives.
European patent application EP 711 828 (Unilever) describes
detergent tablets containing surfactant(s), builders) and a polymer which
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3
acts as a binder and disintegration aid. The binders disclosed in this
document are said to be solid at room temperature and to be added to the
premix to be compressed in the form of a melt. Preferred binders are
relatively high molecular weight polyethylene glycols.
The use of solid polyethylene glycols is also described in German
patent application DE 197 09 411.2 (Henkel). This document teaches
synergistic effects between the polyethylene glycols and overdried
amorphous silicates.
Solutions to the problem of the friability or abrasion resistance of
detergent tablets are disclosed in the prior art, for example in hitherto
unpublished German patent application DE 198 41 146.4 (Henkel KGaA).
This document teaches the addition of 0.25 to 10% by weight - based on
tablet weight - of one or more non-surfactant water-soluble liquid binders to
the premix to be tabletted.
Although the addition of liquids to tabletting premixes is
advantageous because they can be both easily and precisely dosed, it
does lead to technical problems and unwanted side effects. On the one
hand, tabletting premixes are normally prepared from various powders and
granules, so that addition points for liquids involve additional capital
investment in plant; on the other hand, a liquid binder sprayed onto the
premix is distributed throughout the premix so that larger quantities of
binder are required. Another problem is that the liquids applied to the
premix tend to "exude" during the tabletting process, resulting in caking of
the premix on the punches used for tabletting.
Now, the problem addressed by the present invention was to provide
tablets which, for predetermined hardness, would be distinguished by short
disintegration times and which, accordingly, could even be flushed into the
washing process from the dispensing compartment of commercially
available washing machines. In addition to meeting these requirements,
the tablets would have increased resistance to impact and friction, i.e.
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4
would show improved, i.e. reduced, friability and would exhibit reduced
abrasion behavior. In contrast to the solutions proposed in the prior art,
these advantageous tablet properties would be able to be achieved by
addition of solids, thus minimizing dosing and tabletting problems.
Summary of the Invention
It has now been found that the addition of binder compounds of non-
surfactant liquid binders and carriers with a high oil adsorption capacity to
detergent premixes results in tablets which are distinctly more abrasion-
resistant and considerably less friable than the hitherto known tablets. The
use of the additives mentioned has little effect, if any, on the fracture
resistance of the detergent tablets. Problems during the tabletting process,
i.e. the "exudation" of the liquid binder into the die, are also avoided by
this
addition.
The present invention relates to detergent tablets of compacted
particulate detergent containing surfactant(s), builders) and optionally
other typical detergent ingredients, characterized in that, based on tablet
weight, they contain 0.1 to 20% by weight of one or more binder
compounds of
a) 10 to 99% by weight of one or more carrier materials with an oil
adsorption capacity of more than 20 g per 100 g and
b) 1 to 90% by weight of one or more non-surfactant liquid binders.
Detailed Description of the Invention
In the context of the present invention, binder compounds are
understood to be mixtures with the composition mentioned above which,
basically, are present in the form of fine powders. If desired, these fine
powders may be converted into a coarser form by spray drying,
granulation, agglomeration, compacting, pelleting or extrusion processes.
The powder-form carrier materials present in the binder compounds
in accordance with the invention have oil adsorption capacities above 20
grams per 100 g. The oil adsorption capacity is a physical property of a
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substance which can be measured by standardized methods. For
example, British Standards BS1795 and BS3483:Part B7:1982, which both
refer to IS0 78715, are available. In these test methods, a weighed sample
of the particular substance is applied to a dish and refined linseed oil
5 (density: 0.93 gcm-3) is added dropwise from a burette. After each addition,
the powder is intensively mixed with the oil using a spatula, the addition of
oil being continued until a paste of flexible consistency is obtained. This
paste should flow without crumbling. Now, the oil adsorption capacity is the
quantity of oil added dropwise, based on 100 g of adsorbent, and is
expressed in ml/100 g or g/100 g, conversions via the density of the linseed
oil readily being possible. According to the invention, various compounds
which may emanate both from the group of covalent compounds and from
the group of salts are suitable as powder-form components. As already
mentioned, the powder-form components preferably have even higher oil
adsorption capacities, so that preferred detergent tablets are those in which
the carrier materials) has/have an oil adsorption capacity of more than 25
g per 100 g, preferably more than 30 g per 100 g, more preferably more
than 50 g per 100 g and most preferably more than 75 g per 100 g.
Examples of suitable substances are silicates, aluminium silicates and
silicas which are described in detail hereinafter.
The expression "non-surfactant binder" in the context of the present
invention characterizes binders which do not belong to the class of
surfactants. The expression "liquid binder" refers to the aggregate state of
the binder at 25°C/1013.25 mbar. Accordingly, substances which only
melt
or soften at higher temperatures are unsuitable for the purposes of the
present invention.
Preferred quantities in which the binder compounds) is/are used lie
within a relatively narrow range, so that preferred detergent tablets contain
from 0.5 to 15% by weight, preferably from 1 to 10% by weight and more
preferably from 2 to 7.5% by weight, based on tablet weight, of the binder
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6
compound(s).
The binder compounds per se present in accordance with the
invention in the detergent tablets also preferably have a composition that
lies within relatively narrow limits. In preferred detergent tablets according
to the invention, the binder compounds) contains) - based on the
compound -
a) 20 to 90% by weight, preferably 30 to 80% by weight, more preferably
40 to 70% by weight and most preferably 40 to 60% by weight of one
or more carrier materials with an oil adsorption capacity of more than
20 g per 100 g,
b) 10 to 80% by weight, preferably 20 to 70% by weight, more preferably
30 to 60% by weight and most preferably 40 to 60% by weight of one
or more non-surfactant liquid binders.
The binder compounds present in accordance with the invention in
the detergent tablets contain binders) applied to carrier materials.
According to the invention, the carrier materials used are substances with
an oil adsorption capacity of more than 20 g per 100 g, the values of
preferred carrier materials being well above that value. In preferred
detergent tablets, the carrier materials) is/are selected from the group of
silicas, alkali metal silicates and alkali metal aluminium silicates. _
Alkali metal silicates and alkali metal aluminium silicates are
described in detail hereinafter in the description of the builders.
Silicas are compounds with the general formula Si02 ~ nH20.
Whereas the lower members, such as orthosilicic acid and pyrosilicic acid,
are only stable in aqueous solution, silicon dioxide (Si02)x, the anhydride of
silicic acid, occurs as the formal end product of the condensation. During
the condensation reaction, chain-extending, ring-forming and branching
processes take place alongside one another so that the polysilicic acids are
amorphous, In all silicas, the Si atoms are located in the middle of
tetrahedrons which are irregularly attached to one another and at the four
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7
corners of which the oxygen atoms also belonging to the adjacent
tetrahedrons are present. The silicas are distinguished to a particular
degree by an ability to form colloidal solutions of polysilicic acids in which
the silica particles have particle sizes of 5 to 150 nm. These are known as
silica sols. They are unstable to further condensation and can be
converted by aggregation into silica gels.
So far as industrial-scale production is concerned, precipitated
silicas are by far the most important. They are produced from an aqueous
alkali metal silicate solution by precipitation with mineral acids. Colloidal
primary particles are formed and, as the reaction progresses, agglomerate
and finally grow into aggregates. The powder-form voluminous forms have
pore volumes of 2.5 to 15 ml/g and specific surfaces of 30 to 800 m2/g.
Pyrogenic silicas is the generic term for highly disperse silicas which are
produced by flame hydrolysis. In flame hydrolysis, silicon tetrachloride is
decomposed in an oxyhydrogen flame. Pyrogenic silicas have far fewer
OH groups than precipitated silicas on their substantially pore-free surface.
Known commercially available pyrogenic silicas are, for example, Aerosil~
(Degussa), Cab-O-Sil~ (Cabot Corporation, Waltham, Massachusetts) and
HDK (highly disperse silicas).
Besides the silicas and the silicates and aluminium silicates
(zeolites) described in detail hereinafter, highly porous polymers and dried
polymer gels, for example polymer powders from the group of polyvinyl
alcohols, polyacrylates, polyurethanes and polyvinyl pyrrolidones, are also
suitable as carrier materials for the binder compounds.
Suitable non-surfactant liquid binders in the context of the present
invention are any of a number of substances providing they do not belong
to the group of surfactants and are liquid at 25°C/normal pressure.
Preferred binders are diols, such as ethanediol (ethylene glycol, glycol),
1,2-propanediol, 1,3-propanediol, 1,2-, 1,3-, 2,3- and 1,4-butanediol, 1,2-
and 1,5-pentanediol, and also polyethylene glycols and polypropylene
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glycols, triols, such as glycerol and 1,2,6-hexanetriol, polyols liquid under
the conditions mentioned, carbonic acid esters, such as propylene
carbonate or glycerol carbonate, and paraffin oil. Accordingly, preferred
detergent tablets are characterized in that the non-surfactant liquid
binders) is/are selected from the group of diols, triols and polyols, carbonic
acid esters and paraffin oils.
In preferred detergent tablets, compounds containing water-soluble
binders are used as binder compounds. "Water-soluble" binders in the
context of the present invention are binders which are miscible with water
at room temperature. These substances are, for example, the above-
mentioned diols, such as ethanediol (ethylene glycol, glycol), 1,2-
propanediol, 1,3-propanediol, 1,2-, 1,3-, 2,3- and 1,4-butanediol, 1,2- and
1,5-pentanediol, and also polyethylene glycols and polypropylene glycols,
triols, such as glycerol and 1,2,6-hexanetriol, polyols liquid under the
conditions mentioned, carbonic acid esters, such as propylene carbonate
or glycerol carbonate. In preferred detergent tablets according to the
invention, the non-surfactant liquid binders) is/are selected from the group
of polyethylene glycols and polypropylene glycols, glycerol, glycerol
carbonate, ethylene glycol, propylene glycol and propylene carbonate.
Polyethylene glycols (PEGs) suitable for use in the binder
compounds in accordance with the invention are polymers of ethylene
glycol which correspond to general formula I:
H-(O-CH2-CH2)"-OH (I)
in which n may assume a value of 1 (ethylene glycol, see below) to about
16. A factor of crucial importance in evaluating whether a polyethylene
glycol is suitable for use in accordance with the invention is the aggregate
state of the PEG at room temperature, i.e. the solidification point of the
PEG must be below 25°C. Various nomenclatures are used for
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9
polyethylene glycols which can lead to confusion. It is common practice to
indicate the mean relative molecular weight after the initials "PEG", so that
"PEG 200" characterizes a polyethylene glycol having a relative molecular
weight of about 190 to about 210. Under this nomenclature, the standard
polyethylene glycols PEG 200, PEG 300, PEG 400 and PEG 600 may be
used for the purposes of the present invention.
Cosmetic ingredients are covered by another nomenclature in which
the initials PEG are followed by a hyphen and the hyphen is in turn directly
followed by a number which corresponds to the index n in general formula I
above. Under this nomenclature (so-called INCI nomenclature, CTFA
International Cosmetic Ingredient Dictionary and Handbook, 5th Edition,
The Cosmetic, Toiletry and Fragrance Association, Washington, 1997),
PEG-4, PEG-6, PEG-$, PEG-9, PEG-10, PEG-12, PEG-14 and PEG-16,
for example, may be used in accordance with the present invention.
Polyethylene glycols are commercially obtainable, for example under
the trade names of Carbowax~ PEG 200 (Union Carbide), Emkapol~ 200
(ICI Americas), Lipoxol~ 200 MED (HULS America), Polyglycol~ E-200
(Dow Chemical), Alkapol~ PEG 300 (Rhone-Poulenc), Lutrol~ E300
(BASF) and the corresponding trade names with higher numbers.
Polypropylene glycols (PPGs) suitable for use in the binder
compounds in accordance with the invention are polymers of propylene
glycol which correspond to general formula II:
H-(O-C H-C H2) ~-O H ( I I )
CH3
in which n may assume a value of 1 (propylene glycol, see below) and
about 12. Di-, tri- and tetrapropylene glycol, i.e. the representatives with n
= 2, 3 and 4 in formula II, are of particular significance.
Glycerol is a colorless, clear, highly viscous, odorless and sweet-
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tasting hygroscopic liquid with a density of 1.261 which solidifies at
18.2°C.
Originally, glycerol was only a secondary product of the hydrolysis of fats,
but is now industrially synthesized in large quantities. Most industrial
processes start out from propene which is processed to glycerol via the
5 intermediate stages of allyl chloride and epichlorohydrin. Another
industrial
process is the hydroxylation of allyl alcohol with hydrogen peroxide on a
W03 catalyst via the glycidol stage.
Glycerol carbonate can be obtained by transesterifying ethylene
carbonate or dimethyl carbonate with glycerol, ethylene glycol or methanol
10 being obtained as secondary products. Another synthesis route starts out
from glycidol (2,3-epoxy-1-propanol) which is reacted under pressure with
C02 in the presence of catalysts to form glycerol carbonate. Glycerol
carbonate is a clear, low-viscosity liquid with a density of 1.398 gcm-3
which boils at 125-130°C (0.15 mbar).
Ethylene glycol (ethane-1,2-diol, "glycol") is a colorless, viscous,
sweet-tasting and highly hygroscopic liquid which is miscible with water,
alcohols and acetone and which has a density of 1.113. The solidification
point of ethylene glycol is -11.5°C; the liquid boils at 198°C.
Industrially,
ethylene glycol is obtained from ethylene oxide by heating with water under
pressure. Promising production processes can also be built up on the
basis of the acetoxylation of ethylene and subsequent hydrolysis or on the
basis of synthesis gas reactions.
Propylene glycol has two isomers, propane-1,3-diol and propane
1,2-diol. Propane-1,3-diol (trimethylene glycol) is a neutral, colorless and
odorless, sweet-tasting liquid with a density of 1.0597 which solidifies at
-32°C and boils at 214°C. Propane-1,3-diol can be produced from
acrolein
and water with subsequent catalytic hydrogenation.
Commercially by far the most important isomer is propane-1,2-diol
(propylene glycol) which is an oily, colorless and almost odorless liquid with
a density of 1.0381 which solidifies at -60°C and boils at
188°C. Propane
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1,2-diol is produced from propylene oxide by water addition.
Propylene carbonate is a water-clear, low-viscosity liquid with a
density of 1.2057 gcm-3 which melts at -49°C and boils at 242°C.
Propylene carbonate can also be industrially produced by reaction of
propylene oxide and C02 at 200°C/80 bar.
Irrespective of the composition of the binder compounds, preferred
detergent tablets are characterized in that their total content of non
surfactant liquid binders is between 0.1 and 7.5% by weight, preferably
between 0.25 and 5% by weight and more preferably between 0.5 and 3%
by weight, based on tablet weight.
Besides the binder compounds used in accordance with the
invention, the detergent tablets according to the invention contain
surfactants) and builders) as the most important ingredients of detergents
and optionally other ingredients. Other additives which are not normally
used in detergents, but which can develop advantageous effects in tablets,
are disintegration aids.
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
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12
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 ~3-1,4-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
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
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13
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 98/40463 (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 the 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 pm.
According to the invention, preferred detergent tablets aditionally
contain a disintegration aid, preferably a cellulose-based disintegration aid,
preferably in granular, co-granulated or compacted form, in quantities of 0.5
CA 02306722 2000-04-27
14
to 10% by weight, preferably in quantities of 3 to 7% by weight and more
preferably in quantities of 4 to 6% by weight, based on tablet weight.
The detergent tablets according to the invention additionally contain
one or more builders. Any of the builders normally used in detergents may
be present in the detergent tablets according to the invention, including in
particular zeolites, silicates, carbonates, organic co-builders and also -
providing there are no ecological objections to their use - phosphates.
Suitable crystalline layer-form sodium silicates correspond to the
general formula NaMSiXO~+~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 ~3- and s-sodium
disilicates Na2Si205y H20 are particularly preferred, ~i-sodium disilicate
being obtainable, for example, by the process described in International
patent application WO-A- 91/08171.
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
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
CA 02306722 2000-04-27
diffraction maxima in electron diffraction experiments. This may be
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-
5 ray amorphous silicates such as these, which also dissolve with delay in
relation to conventional waterglasses, are described for example in
German patent application DE-A-44 00 024. Compacted amorphous
silicates, compounded amorphous silicates and overdried X-ray-amorphous
silicates are particularly preferred.
10 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 preferred to use, for example, a co-
15 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)KZO ~ AI203 ~ (2 - 2.5)Si02 ~ (3.5 - 5.5) H20.
The zeolite may be used both as a builder in a granular compound and as
a kind of "powder" to be applied to the entire mixture to be tabletted, both
routes normally being used to incorporate the zeolite in the premix.
Suitable zeolites have a mean particle size of less than 10 pm (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.
Among the large number of commercially available phosphates, alkali
CA 02306722 2000-04-27
16
metal phosphates have the greatest importance in the detergent industry,
pentasodium triphosphate and pentapotassium triphosphate (sodium and
potassium tripolyphosphate) being particularly preferred.
"Alkali metal phosphates" is the collective term for the alkali metal
(more particularly sodium and potassium) salts of the various phosphoric
acids, including metaphosphoric acids (HP03)" and orthophosphoric acid
(H3P04) and representatives of higher molecular weight. The phosphates
combine several advantages: they act as alkalinity sources, prevent lime
deposits on machine parts and lime incrustations in fabrics and, in addition,
contribute towards the cleaning effect.
Sodium dihydrogen phosphate (NaH2P04) exists as the dehydrate
(density 1.91 gcm-3, melting point 60°) and as the monohydrate (density
2.04 gcm-3). Both salts are white readily water-soluble powders which, on
heating, lose the water of crystallization and, at 200°C, are converted
into
the weakly acidic diphosphate (disodium hydrogen diphosphate,
Na2H2P207) and, at higher temperatures, into sodium trimetaphosphate
(Na3P309) and Maddrell's salt (see below). NaH2P04 shows an acidic
reaction. It is formed by adjusting phosphoric acid with sodium hydroxide
to a pH value of 4.5 and spraying the resulting "mash". Potassium
dihydrogen phosphate (primary or monobasic potassium phosphate,
potassium biphosphate, KDP), KH2P04, is a white salt with a density of
2.33 gcm-3, has a melting point of 253° [decomposition with formation
of
potassium polyphosphate (KP03)X] and is readily soluble in water.
Disodium hydrogen phosphate (secondary sodium phosphate),
Na2HP04, is a colorless, readily water-soluble crystalline salt. It exists in
water-free form and with 2 moles (density 2.066 gcm-3, water loss at
95°), 7
moles (density 1.68 gcm-3, melting point 48° with loss of 5 H20) and 12
moles of water (density 1.52 gcm-3, melting point 35° with loss of 5
H20),
becomes water-free at 100° and, on fairly intensive heating, is
converted
into the diphosphate Na4P207. Disodium hydrogen phosphate is prepared
CA 02306722 2000-04-27
17
by neutralization of phosphoric acid with soda solution using phenol-
phthalein as indicator. Dipotassium hydrogen phosphate (secondary or
dibasic potassium phosphate), KZHP04, is an amorphous white salt which
is readily soluble in water.
Trisodium phosphate, tertiary sodium phosphate, Na3P04, consists
of colorless crystals which have a density of 1.62 gcm~3 and a melting point
of 73-76° (decomposition) as the dodecahydrate, a melting point of
100° as
the decahydrate (corresponding to 19-20% P205) and a density of 2.536
gcm-3 in water-free form (corresponding to 39-40% P2O5). Trisodium
phosphate is readily soluble in water through an alkaline reaction and is
prepared by concentrating a solution of exactly 1 mole of disodium
phosphate and 1 mole of NaOH by evaporation. Tripotassium phosphate
(tertiary or tribasic potassium phosphate), K3P04, is a white deliquescent
granular powder with a density of 2.56 gcm~, has a melting of 1340° and
is
readily soluble in water through an alkaline reaction. It is formed, for
example, when Thomas slag is heated with coal and potassium sulfate.
Despite their higher price, the more readily soluble and therefore highly
effective potassium phosphates are often preferred to corresponding
sodium compounds in the detergent industry.
Tetrasodium diphosphate (sodium pyrophosphate), Na4P207, exists
in water-free form (density 2.534 gcm-3, melting point 988°, a figure
of 880°
has also been mentioned) and as the decahydrate (density 1.815 - 1.836
gcm-3, melting point 94° with loss of water). Both substances are
colorless
crystals which dissolve in water through an alkaline reaction. Na4P207 is
formed when disodium phosphate is heated to >200° or by reacting
phosphoric acid with soda in a stoichiometric ratio and spray-drying the
solution. The decahydrate complexes heavy metal salts and hardness
salts and, hence, reduces the hardness of water. Potassium diphosphate
(potassium pyrophosphate), K4P207, exists in the form of the trihydrate and
is a colorless hygroscopic powder with a density of 2.33 gcm-3 which is
CA 02306722 2000-04-27
18
soluble in water, the pH value of a 1 % solution at 25° being 10.4.
Relatively high molecular weight sodium and potassium phosphates
are formed by condensation of NaH2P04 or KH2P04. They may be divided
into cyclic types, namely the sodium and potassium metaphosphates, and
chain types, the sodium and potassium polyphosphates. The chain types
in particular are known by various different names: fused or calcined
phosphates, Graham's salt, Kurrol's salt and Maddrell's salt. All higher
sodium and potassium phosphates are known collectively as condensed
phosphates.
The industrially important pentasodium triphosphate, Na5P30~o
(sodium tripolyphosphate), is a non-hygroscopic white water-soluble salt
which crystallizes without water or with 6 H20 and which has the general
formula Na0-[P(O)(ONa)-O]~-Na where n = 3. Around 17 g of the salt free
from water of crystallization dissolve in 100 g of water at room temperature,
around 20 g at 60° and around 32 g at 100°. After heating of the
solution
for 2 hours to 100°, around 8% orthophosphate and 15% diphosphate are
formed by hydrolysis. In the preparation of pentasodium triphosphate,
phosphoric acid is reacted with soda solution or sodium hydroxide in a
stoichiometric ratio and the solution is spray-dried. Similarly to Graham's
salt and sodium diphosphate, pentasodium triphosphate dissolves many
insoluble metal compounds (including lime soaps, etc.). Pentapotassium
triphosphate, K5P3O~p (potassium tripolyphosphate), is marketed for
example in the form of a 50% by weight solution (> 23% P205, 25% K20).
The potassium polyphosphates are widely used in the detergent industry.
Sodium potassium tripolyphosphates, which may also be used in
accordance with the invention, also exist. They are formed for example
when sodium trimetaphosphate is hydrolyzed with KOH:
(NaP03)3 + 2 KOH ~ Na3K2P30~o + H20
CA 02306722 2000-04-27
19
According to the invention, they may be used in exactly the same
way as sodium tripolyphosphate, potassium tripolyphosphate or mixtures
thereof. Mixtures of sodium tripolyphosphate and sodium potassium
tripolyphosphate or mixtures of potassium tripolyphosphate and sodium
potassium tripolyphosphate or mixtures of sodium tripolyphosphate and
potassium tripolyphosphate and sodium potassium tripolyphosphate may
also be used in accordance with the invention.
Organic cobuilders suitable for use in the detergent tablets
according to the invention are, in particular, polycarboxylates/polycarboxylic
acids, polymeric polycarboxylates, aspartic acid, polyacetals, dextrins,
other organic cobuilders (see below) and phosphonates. These classes of
substances are described in 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 which bear more
than one acid function. Examples of such carboxylic acids are citric acid,
adipic acid, succinic acid, glutaric acid, malic acid, tartaric acid, malefic
acid,
fumaric acid, sugar acids, aminocarboxylic 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.
The acids per se may also be used. Besides their builder effect, the
acids also typically have the property of an acidifying component and,
hence, also serve to establish a relatively low and mild pH value in
detergents. Citric acid, succinic acid, glutaric acid, adipic 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 or polymethacrylic acid, for
example those with a relative molecular weight of 500 to 70,000 g/mole.
CA 02306722 2000-04-27
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
5 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
10 generally higher than the molecular weights mentioned in this
specification.
Particularly suitable polymers are 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
15 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
20 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 detergent is preferably from 0.5 to 20% by weight
and more preferably from 3 to 10% by weight.
In order to improve solubility in water, the polymers may also contain
allyl sulfonic acids, such as allyloxybenzene sulfonic acid and methallyl
sulfonic acid, as monomer.
CA 02306722 2000-04-27
21
Other particularly preferred polymers are biodegradable polymers of
more than two different monomer units, for example 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 which are described in
German patent applications DE-A-43 03 320 and DE-A-44 17 734 and
which preferably contain acrolein and acrylic acid/acrylic acid salts or
acrolein and vinyl acetate as monomers.
Other preferred builders are polymeric aminodicarboxylic acids, salts
or precursors thereof. Particular preference is attributed to polyaspartic
acids or salts and derivatives thereof which, according to German patent
application DE-A-195 40 086, are also said to have a bleach-stabilizing
effect in addition to their co-builder properties.
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 3 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
CA 02306722 2000-04-27
22
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 42? 349, EP-A-0
472 042 and EP-A-0 542 496 and from International patent applications
WO 92118542, WO 93108251, WO 93/16110, WO 94/28030, WO 95107303,
WO 95112619 and WO 95120608. An oxidized oligosaccharide
corresponding to German patent application DE-A-196 00 018 is also
suitable. A product oxidized at Cs 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
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 95120029.
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 the sodium salt, the disodium salt showing a
neutral reaction and the tetrasodium salt an alkaline reaction (pH 9).
CA 02306722 2000-04-27
23
Preferred aminoalkane phosphonates are ethylenediamine tetramethylene
phosphonate (EDTMP), diethylenetriamine pentamethylenephosphonate
(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 or as the hepta- and octasodium salts of DTPMP. Of the
phosphonates, HEDP is preferably used as a builder. In addition, the
aminoalkane phosphonates have a pronounced heavy metal binding
capacity. Accordingly, it can be of advantage, particularly where the
detergents also contain bleach, to use aminoalkane phosphonates, more
particularly 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.
The quantity of builder used is normally between 10 and 70% by
weight, preferably between 15 and 60% by weight and more preferably
between 20 and 50% by weight. The quantity of builder used is again
dependent upon the particular application envisaged, so that bleach tablets
can contain larger quantities of builders (for example between 20 and 70%
by weight, preferably between 25 and 65% by weight and more preferably
between 30 and 55% by weight) than, for example, laundry detergent
tablets (normally 10 to 50% by weight, preferably 12.5 to 45% by weight
and more preferably 17.5 to 37.5% by weight).
Preferred detergent tablets additionally contain one or more
surfactant(s). Anionic, nonionic, cationic and/or amphoteric surfactants or
mixtures thereof may be used in the detergent tablets according to the
invention. Mixtures of anionic and nonionic surfactants are preferred from
the performance point of view. The total surfactant content of the tablets is
between 5 and 60% by weight, based on tablet weight, surfactant contents
above 15% by weight being preferred. Dishwasher tablets may contain
surfactants in smaller quantities, for example below 2% by weight.
The anionic surfactants used are, for example, those of the sulfonate
CA 02306722 2000-04-27
24
and sulfate type. Preferred surfactants of the sulfonate type are C9_~3 alkyl
benzenesulfonates, olefin sulfonates, i.e. mixtures of alkene and hydroxy-
alkane 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~2_~8 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, palm
kernel or tallow acids, are also suitable.
Other suitable anionic surfactants are sulfonated fatty acid glycerol
esters, i.e. 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 C6_22 fatty acids,
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_~$ fatty
alcohols, for example coconut alcohol, tallow alcohol, lauryl, myristyl, cetyl
or stearyl alcohol, or C»2o oxoalcohols and the corresponding 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_~6 alkyl sulfates and C~2_~5 alkyl
sulfates and also C~4_~5 alkyl sulfates are particularly preferred from the
washing performance point of view. Other suitable anionic surfactants are
CA 02306722 2000-04-27
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 commercially obtainable as
products of the Shell Oil Company under the name of DAN~.
The sulfuric acid monoesters of linear or branched C~_2~ alcohols
5 ethoxylated with 1 to 6 moles of ethylene oxide, such as 2-methyl-branched
C9_» alcohols containing on average 3.5 moles of ethylene oxide (EO) or
C~Z_~8 fatty alcohols containing 1 to 4 EO, are also suitable. In view of
their
high foaming capacity, they are normally used in only relatively small
quantities, for example in quantities of 1 to 5% by weight, in dishwashing
10 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,
15 ethoxylated fatty alcohols. Preferred sulfosuccinates contain C$_~8 fatty
alcohol molecules or mixtures thereof. Particularly preferred
sulfosuccinates contain a fatty alcohol molecule derived from ethoxylated
fatty alcohols which, considered in isolation, represent nonionic surfactants
(for a description, see below). Of these sulfosuccinates, those of which the
20 fatty alcohol molecules 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
25 soaps are, in particular, 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 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
CA 02306722 2000-04-27
26
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.
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 group may be linear or, preferably,
methyl-branched in the 2-position or may contain linear and methyl
branched groups in the form of the mixtures typically present in oxoalcohol
groups. However, alcohol ethoxylates containing linear groups 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_~4 alcohols containing 3 EO or 4 EO, C9_» alcohol containing 7 EO,
C~~~5 alcohols containing 3 EO, 5 EO, 7 EO or 8 EO, C~2_~$ 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_~a 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.
Suitable other nonionic surfactants are alkyl glycosides with the
general formula RO(G)X where R is a primary, linear or methyl-branched,
more particularly 2-methyl-branched, 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
oligomerization x, which indicates the distribution of monoglycosides and
oligoglycosides, is a number of 1 to 10 and preferably 1.2 to 1.4.
CA 02306722 2000-04-27
27
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 58/217598
or which are preferably produced by the process described in International
patent application WO-A-90113533.
Nonionic surfactants of the amine oxide type, for example N
coconutalkyl-N,N-dimethylamine oxide and N-tallowalkyl-N,N-dihydroxy
ethylamine 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 (III):
R'
R-CO-N-[Z] (III)
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 (IV):
CA 02306722 2000-04-27
28
R' -O-R2
R-C O-N-[Z] ( I V)
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-95107331.
According to the invention, preferred detergent tablets contain
anionic and nonionic surfactant(s). Performance-related advantages can
arise out of certain quantity ratios in which the individual classes of
surfactants are used. Particularly preferred detergent tablets contain
anionic and/or nonionic surfactants) and have total surfactant contents
above 2.5% by weight, preferably above 5% by weight and more preferably
above 10% by weight, based on tablet weight.
For example, particularly preferred detergent tablets are charac-
terized in that the ratio of anionic surfactants) to nonionic surfactants) is
from 10:1 to 1:10, preferably from 7.5:1 to 1:5 and more preferably from 5:1
to 1:2. Other preferred detergent tablets are characterized in that they
contain surfactant(s), preferably anionic and/or nonionic surfactant(s), in
CA 02306722 2000-04-27
29
quantities of 5 to 40% by weight, preferably 7.5 to 35% by weight, more
preferably 10 to 30% by weight and most preferably 12.5 to 25% by weight,
based on the weight of the tablet.
It can be of advantage from the performance point of view if certain
classes of surfactants are missing from certain phases of the detergent
tablets or from the entire tablet, i.e. from every phase. In another important
embodiment of the present invention, therefore, at least one phase of the
tablets is free from nonionic surfactants.
Conversely, a positive effect can also be obtained through the
presence of certain surfactants in individual phases or in the tablet as a
whole, i.e. in every phase. Introducing the alkyl polyglycosides described
above has proved to be of particular advantage, so that detergent tablets in
which at least one phase of the tablet contains alkyl polyglycosides are
preferred.
As with the nonionic surfactants, the omission of anionic surfactants
from individual phases or from all phases can result in detergent tablets
which are more suitable for certain applications. Accordingly, detergent
tablets where at least one phase of the tablet is free from anionic
surfactants are also possible in accordance with the present invention.
Besides the ingredients mentioned thus far (surfactant, builder and
disintegration aid) and in addition to the binder compound present in the
tablets in accordance with the invention, the detergent tablets according to
the invention may contain other substances from the group of bleaching
agents, bleach activators, enzymes, pH regulators, perfumes, perfume
carriers, fluorescers, dyes, foam inhibitors, silicone oils, redeposition
inhibitors, optical brighteners, discoloration inhibitors, dye transfer
inhibitors
and corrosion inhibitors.
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,
CA 02306722 2000-04-27
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. Where bleaching agents are used, it is again
5 possible to leave out surfactants and/or builders so that pure bleach
tablets
can be produced. If such bleach tablets are to be added to laundry, a
combination of sodium percarbonate with sodium sesquicarbonate is
preferably used irrespective of what other ingredients the tablets contain. If
detergent or bleach tablets for dishwashing machines are being produced,
10 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)
15 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, s-phthalimidoperoxycaproic acid
[phthaloiminoperoxyhexanoic acid (PAP)], o-carboxybenzamidoperoxy-
20 caproic acid, N-nonenylamidoperadipic acid and N-nonenylamido
persuccinates, 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-amino
25 percaproic 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-
30 isocyanuric acid and/or dichloroisocyanuric acid (DICA) and/or salts
thereof
CA 02306722 2000-04-27
31
with cations, such as potassium and sodium. Hydantoin compounds, such
as 1,3-dichloro-5,5-dimethyl hydantoin, are also suitable.
In order to obtain an improved bleaching effect at washing
temperatures of 60°C or lower, bleach activators may be incorporated as
a
sole constituent or as an ingredient of component b). According to the
invention, compounds which form aliphatic peroxocarboxylic acids
preferably containing 1 to 10 carbon atoms and more preferably 2 to 4
carbon atoms and/or optionally substituted perbenzoic acid under
perhydrolysis conditions may be used as bleach activators. Suitable
bleach activators are substances which contain O- and/or N-acyl groups
with the number of carbon atoms indicated and/or optionally substituted
benzoyl groups. Preferred bleach activators are polyacylated
alkylenediamines, more especially tetraacetyl ethylenediamine (TAED),
acylated triazine derivatives, more particularly 1,5-diacetyl-2,4-
dioxohexahydro-1,3,5-triazine (DADHT), acylated .glycol urils, more
particularly tetraacetyl glycol uril (TAGU), N-acylimides, more particularly
N-nonanoyl succinimide (NOSI), acylated phenol sulfonates, more
particularly n-nonanoyl- or isononanoyl-oxybenzenesulfonate (n- or iso-
NOBS), carboxylic anhydrides, more especially phthalic anhydride,
acylated polyhydric alcohols, more especially triacetin, ethylene glycol
diacetate and 2,5-diacetoxy-2,5-dihydrofuran.
In addition to or instead of the conventional bleach activators, 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, Mn-, Fe-, Co-, Ru- or Mo-salen
complexes or carbonyl complexes. Mn-, Fe-, Co-, Ru-, Mo-, Ti-, V- and Cu-
complexes with N-containing tripod ligands and Co-, Fe-, Cu- and Ru-
ammine complexes may also be used as bleach catalysts. According to
the invention, bleach-boosting active-substance combinations obtainable
by thoroughly mixing a water-soluble salt of a divalent transition metal
CA 02306722 2000-04-27
32
selected from cobalt, iron, copper and ruthenium and mixtures thereof, a
water-soluble ammonium salt and optionally a peroxygen-based oxidizing
agent and inert carrier materials may also be used as bleach catalysts.
Suitable enzymes 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, and discoloration in
the washing process. Cellulases and other glycosyl hydrolases can
contribute towards color retention and towards increasing fabric softness by
removing pilling and microfibrils. Oxidoreductases may also be used for
bleaching and for inhibiting dye transfer. 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 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. Preferred cellulases are cellobiohydrolases, endoglucanases
and ~3-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.
CA 02306722 2000-04-27
33
The enzymes may be adsorbed to supports and/or encapsulated in
membrane materials 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
preferably from 0.5 to about 4.5% by weight.
The choice of the particular enzymes is also dependent on the
application envisaged for the detergent tablets according to 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, 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, 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.
In dishwasher tablets also, the enzymes may be adsorbed to
supports and/or encapsulated in membrane materials to protect them
against premature decomposition. The percentage content of the
enzymes, enzyme mixtures or enzyme granules may again be, for
example, from about 0.1 to 5% by weight and is preferably from 0.5 to
CA 02306722 2000-04-27
34
about 4.5% by 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 dishwashing machines. Known silver
protectors 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 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, hydroxyhydroquinone,
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 protect tableware against corrosion.
In addition, the detergent tablets 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
CA 02306722 2000-04-27
and 1 to 15% by weight of hydroxypropoxyl 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
5 anionically and/or nonionically modified derivatives thereof. Of these, the
sulfonated derivatives of phthalic acid and terephthalic acid polymers are
particularly preferred.
The tablets may contain derivatives of diaminostilbenedisulfonic acid
or alkali metal salts thereof as optical brighteners. Suitable optical
10 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
15 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)-Biphenyl, may
also be present. Mixtures of the brighteners mentioned above may also be
used.
Dyes and perfumes are added to the detergent tablets according to
20 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,
25 ether, aldehyde, ketone, alcohol and hydrocarbon type. Perfume com-
pounds 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 benzoate, benzyl formate,
ethyl methyl phenyl glycinate, ally) cyclohexyl propionate, styrallyl
30 propionate and benzyl salicylate. The ethers include, for example, benzyl
CA 02306722 2000-04-27
36
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
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/fragrances can 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
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
CA 02306722 2000-04-27
37
not to color them.
Detergent tablets are produced by applying pressure to a mixture to
be tabletted which is accommodated in the cavity of a press. In the most
simple form of tabletting, the mixture to be tabletted is tabletted directly,
i.e.
without preliminary granulation. The advantages of this so-called direct
tabletting lie in its simple and inexpensive application because no other
process steps and hence no other items of equipment are required.
However, these advantages are often offset by disadvantages. Thus, a
powder mixture which is to be directly tabletted must show adequate
plasticity and good flow properties and should not have any tendency to
separate during storage, transportation and filling of the die. With many
mixtures, these three requirements are very difficult to satisfy with the
result
that direct tabletting is often not applied, particularly in the production of
detergent tablets. Accordingly, the normal method of producing detergent
tablets starts out from powder-form components ("primary particles") which
are agglomerated or granulated by suitable methods to form secondary
particles with a larger particle diameter. These granules or mixtures of
different granules are then mixed with individual powder-form additives and
tabletted.
Accordingly, the present invention also relates to a process for the
production of detergent tablets by tabletting a particulate premix in known
manner, characterized in that the premix contains one or more binder
compounds of
a) 10 to 99% by weight of one or more carrier materials with an oil
adsorption capacity of more than 20 g per 100 g and
b) 1 to 90% by weight of one or more non-surfactant liquid binders.
So far as preferred embodiments of the process according to the
invention are concerned, reference may be made here to the foregoing
observations: what was said in reference to the detergent tablets according
to the invention applies similarly to the process according to the invention.
CA 02306722 2000-04-27
38
For example, preferred processes according to the invention are
characterized in that the premix contains the binder compounds) in
quantities of 0.5 to 15% by weight, preferably in quantities of 1 to 10% by
weight and more preferably in quantities of 2 to 7.5% by weight, based on
the weight of the premix.
The foregoing observations also apply equally to preferred
compositions of the binder compounds used in accordance with the
invention. Accordingly, preferred processes are characterized in that the
binder compounds contain - based on the compound -
a) 20 to 90% by weight, preferably 30 to 80% by weight, more preferably
40 to 70% by weight and most preferably 40 to 60% by weight of one
or more carrier materials with an oil adsorption capacity of more than
g per 100 g, preferably more than 25 g per 100 g, more preferably
15 more than 30 g per 100 g, most preferably more than 50 g per 100 g
and, in one particularly advantageous embodiment, more than 75 g per
100 g, the carrier materials preferably being selected from the group of
silicas, alkali metal silicates and alkali metal aluminium silicates,
b) 10 to 80% by weight, preferably 20 to 70% by weight, more preferably
20 30 to 60% by weight and most preferably 40 to 60% by weight of one
or more non-surfactant liquid binders, preferably from the group of
silicas, alkali metal silicates and alkali metal aluminium silicates,
polyethylene glycols and polypropylene glycols, glycerol, glycerol
carbonate, ethylene glycol, propylene glycol and propylene carbonate
being particularly preferred.
In preferred variants of the process, the binder compounds also
satisfy certain particle size criteria. Thus, preferred processes according to
the invention are characterized in that at least 60% by weight, preferably at
least 75% by weight and more preferably at least 90% by weight - based on
CA 02306722 2000-04-27
39
the compound - of the binder compounds have particle sizes below 600
pm. In a particularly preferred embodiment, the binder compounds have a
mean particle size below 400 Nm.
According to the invention, preferred detergent tablets are produced
by tabletting a particulate premix of surfactant-containing granules of at
least one type and at least one powder-form component subsequently
added. The surfactant-containing granules may be produced by
conventional industrial granulation processes, such as compacting,
extrusion, mixer granulation, pelleting or fluidized bed granulation. It is of
advantage so far as the subsequent detergent tablets are concerned if the
premix to be tabletted has a bulk density approaching that of typical
compact detergents. In one particularly preferred embodiment, the premix
to be tabletted has a bulk density of at least 500 g/I, preferably of at least
600 g/I and more preferably of at least 700 g/I.
In preferred variants of the process, the surfactant-containing
granules also satisfy certain particle size criteria. Thus, preferred
processes according to the invention are characterized in that the
surfactant-containing granules have particle sizes of 100 to 2000 Nm,
preferably 200 to 1800 Nm, more preferably 400 to 1600 Nm and most
preferably 600 to 1400 Nm.
Besides the active substances (anionic and/or nonionic and/or
cationic and/or amphoteric surfactants), the surfactant granules preferably
contain carrier materials which, in one particularly preferred embodiment,
emanate from the group of builders. Accordingly, particularly
advantageous processes are characterized in that the surfactant-containing
granules contain anionic and/or nonionic surfactants and builders and have
total surfactant contents of at least 10% by weight, preferably at least 20%
by weight and more preferably at least 25% by weight.
Before the particulate premix is compressed to form detergent
tablets, it may be "powdered" with fine-particle surface treatment materials.
CA 02306722 2000-04-27
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
5 premix 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 Wiley & Sons, New
10 York/London/Sydney/Toronto, 1974, page 92). Besides zeolite X, there-
fore, zeolite Y and faujasite and mixtures of these compounds may also be
used, pure zeolite X being preferred. Mixtures or co-crystallizates of
faujasite zeolites with other zeolites which need not necessarily belong to
zeolite structure group 4 may also be used as powdering materials, in
15 which case at least 50% by weight of the powdering material
advantageously consists of a faujasite zeolite.
According to the invention, preferred detergent tablets consist of a
particulate premix containing granular components and powder-form
substances subsequently added, the - or one of the - powder-form
20 components subsequently incorporated being a faujasite zeolite with
particle sizes below 100 Nm, preferably below 10 Nm and more preferably
below 5 Nm and making 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 tabletted.
25 Besides the components mentioned (surfactant, builder and
disintegration aid), the premixes to be tabletted may additionally contain
one or more substances from the group of bleaching agents, bleach
activators, enzymes, pH regulators, perfumes, perfume carriers,
fluorescers, dyes, foam inhibitors, silicone oils, redeposition inhibitors,
30 optical brighteners, discoloration inhibitors, dye transfer inhibitors and
CA 02306722 2000-04-27
41
corrosion inhibitors. These substances are described in the foregoing.
The tablets according to the invention are produced by first dry-
mixing the ingredients - which may be completely or partly pregranulated -
and then shaping/forming, more particularly tabletting, the resulting mixture
using conventional processes. 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 dosing, even at high
tablet throughputs, is preferably achieved by volumetric dosing 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.).
CA 02306722 2000-04-27
42
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
production volumes, it is preferred to use eccentric tablet presses in which
the punches) is/are fixed to an eccentric disc 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 disc, 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
CA 02306722 2000-04-27
43
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.
Where rotary presses are used for tabletting, it has proved to be of
advantage to carry out the tabletting process with minimal variations in the
weight of the tablets. Variations in tablet hardness can also be reduced in
this way. Minimal variations in weight can be achieved as follows:
- using plastic inserts with minimal thickness tolerances
- low rotor speed
- large filling shoe
- adapting the rotational speed of the filling shoe blade to the rotor speed
- filling shoe with constant powder height
- decoupling the filling shoe from the powder supply.
Any of the nonstick coatings known in the art may be used to reduce
caking on the punch. Plastic coatings, plastic inserts or plastic punches are
particularly advantageous. Rotating punches have also proved to be of
advantage; if possible, the upper and lower punches should be designed
for rotation. If rotating punches are used, there will generally be no need
CA 02306722 2000-04-27
44
for a plastic insert. In that case, the surfaces of the punch should be
electropolished.
It has also been found that long tabletting times are advantageous.
These can be achieved by using pressure rails, several pressure rollers or
low rotor speeds. Since variations in tablet hardness are caused by
variations in the pressures applied, systems which limit the tabletting
pressure should be used. Elastic punches, pneumatic compensators or
spring elements in the force path may be used. The pressure roller can
also be spring-mounted.
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; Horn & Noack Pharmatechnik GmbH, Worms; IMA
Verpackungssysteme GmbH Viersen; KILIAN, Cologne; KOMAGE, Kell am
See, KORSCH Pressen GmbH, Berlin; and Romaco GmbH, Worms. Other
suppliers are, for example Dr. Herbert Pete, Vienna (AU); Mapag
Maschinenbau AG, Bern (Switzerland); BWI Manesty, Liverpool (GB); I.
Holand Ltd., Nottingham (GB); and Courtoy N.V., Halle (BE/LU) and
Medicopharm, Kamnik (SI). One example of a particularly suitable
tabletting machine is the model HPF 630 hydraulic double-pressure press
manufactured by LAEIS, D. Tabletting tools are obtainable, for example,
from Adams Tablettierwerkzeuge Dresden; Wilhelm Fett GmbH,
Schwarzenbek; Klaus Hammer, Solingen; Herber & Sohne GmbH,
Hamburg; Hofer GmbH, Weil; Horn & Noack, Pharmatechnik GmbH,
Worms; Ritter Pharmatechnik GmbH, Hamburg; Romaco GmbH, Worms
and Notter Werkzeugbau, Tamm. Other suppliers are, for example, Senss
AG, Reinach (CH) and Medicopharm, Kamnik (SI).
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,
CA 02306722 2000-04-27
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
5 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
10 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.
15 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.
20 However, it is of course readily possible - and preferred in accordance
with
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
25 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.
30 In another possible embodiment, however, the various components
CA 02306722 2000-04-27
46
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
bleaching agent and any bleach activators or bleach catalysts 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
constituents 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
CA 02306722 2000-04-27
47
example, with aqueous solutions or emulsions or a coating may be
obtained by the process known as melt coating.
After pressing, the 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:
a=
2P
~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.
The present invention also relates to the use of binder compounds of
a) 10 to 99% by weight of one or more carrier materials with an oil
adsorption capacity of more than 20 g per 100 g,
b) 1 to 90% by weight of one or more non-surfactant liquid binders
for improving the hardness and disintegration time and/or the abrasion
resistance of detergent tablets. This use of the detergent compounds
mentioned in accordance with the invention leads to tablets with
advantageous properties, as the following non-limiting Examples show.
The foregoing observations on the process according to the invention apply
equally to preferred embodiments of the use according to the invention
(particle sizes, other ingredients, composition of the premix, etc.).
Examples
Surfactant-containing granules (for composition, see Table 1 ), which
were used as the basis for a particulate premix, were produced by
granulation in a 5 liter Lodige plowshare mixer. After granulation, the
granules were dried for 30 minutes in a Glatt fluidized bed dryer at an
CA 02306722 2000-04-27
48
inflowing air temperature of 60°C. After drying, fine particles (< 0.6
mm)
and coarse particles (> 1.6 mm) were removed by sieving.
This premix was produced by mixing the surfactant-containing
granules with bleaching agent, bleach activator and other additive
components. 3% by weight of a binder compound of which the composition
is shown in Table 2 were added to Example E according to the invention in
the production of the premix so that the percentage amounts of the other
components differ from those of Comparison Example C which contained
no binder compound. Premixes E and C were tabletted in a Korsch
eccentric press (tablet diameter 44 mm, tablet height 22 mm, tablet weight
37.5 g), no "exudation" of the binder from the tablet being observed. The
composition of the premixes to be tabletted (and hence of the tablets) is
shown in Table 3.
Table 1:
Composition of the surfactant granules [% by weight]
C9_~3 alkyl benzenesulfonate 18.6
C~2_~8 fatty alcohol + 7 EO 5.7
C~2_~8 fatty alcohol sulfate 5.4
Soap 1.6
Optical brightener 0.3
Sodium carbonate 16.6
Sodium silicate 5.4
Acrylic acid/maleic acid copolymer5.4
Zeolite A (water-free active 29.9
substance)
Na hydroxyethane-1,1-diphosphonate0.8
Water, salts -- Balance
J
CA 02306722 2000-04-27
49
Table 2:
Composition of the binder compound [% by weight]:
Overdried waterglass (sodium 57.5
silicate, amorphous, <10%
by
weight water)
Glycerol 42.5
Table 3:
Composition of the premixes [% by weight]
E C
Surfactant granules (Table 1) 64.5 65.8
Sodium perborate monohydrate 15.0 15.8
TAED 5.0 5.3
Foam inhibitor 3.0 3.2
Polyacrylate 1.0 1.0
Enzymes 2.0 2.1
Perfume 0.5 0.5
Wessalith~ P (zeolite A) 1.0 1.0
Disintegration aid (cellulose) 5.0 5.3
Binder compound 3.0 -
The hardness of the tablets was measured by deforming a tablet
until it broke, the force being applied to the sides of the tablet and the
maximum force withstood by the tablet being determined.
To determine tablet disintegration, a tablet was placed in a glass
beaker filled with water (600 ml water, temperature 30°C) and the time
taken for the tablet to disintegrate completely was measured. The experi-
mental data of the individual tablet series are shown in Table 4:
CA 02306722 2000-04-27
Table 4:
Detergent tablets containing binder compound [physical data]
Tablet E C
Tablet hardness [N] 34 36
Tablet disintegration [secs.]22 23
As can be seen from Table 4, the addition of the binder compound
has hardly any influence on the fracture resistance or disintegration time of
the laundry detergent tablets. In order to determine friability or abrasion
behavior and brittle fracture behavior, tablets E according to the invention
and comparison tablets C were introduced into a friabilator (rotating glass
drum - diameter 180 mm, width 40 mm - which was provided with three
triangular obstacle ribs - height 20 mm, base width 15 mm - extending
transversely of the direction of rotation and arranged at equal intervals
apart). At a rotational speed of 20 r.p.m., the time required for a tablet to
break into several large parts was determined. The results of the
measurements are shown in Table 5:
Table 5:
Results of the brittle fracture and friability measurements [s]
Fracture hardness26 N ~ 37 47 N
N
E 330 _ 1000
460
C 20 60 100
The data in Table 5 show that the effect of adding the binder
compound is that, under mechanical load, the detergent tablets only break
up into several parts much later, i.e. are more stable. In addition, the
abrasion tendency of the tablets is distinctly reduced.
