Note: Descriptions are shown in the official language in which they were submitted.
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1
DETERGENT TABLETS WITH IMPROVED ABRASION RESISTANCE
Field of the Invention
This invention relates generally to compact shaped bodies having
detersive properties. Detersive shaped bodies include, for example, laundry
detergent tablets, tablets for dishwashing machines or for cleaning hard
surfaces,
bleach tablets for use in washing or dishwashing machines, water softening
tablets or stain remover tablets. More particularly, the present invention
relates
to 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 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
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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.
European patent application EP 711 828 (Unilever) describes detergent
tablets containing surfactant(s), builders) and a polymer which acts as a
binding
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 slid polyethylene glycols is also described in German patent
application DE 197 09 411.2 (Henkel). This document teaches synergistic
effects
between the ethylene 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
adding 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
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V
3
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. It has also been found that liquids
added to the premix can adversely affect the shelf life of the tablets. In
particular,
their disintegration properties deteriorate significantly at relatively high
storage
temperatures with the result that the tablets may no longer disintegrate in a
sufficiently short time. If, therefore, the tablets are added from the
dispensing
compartment, large quantities of detergent remain undissolved after the final
rinse cycle.
Summary of the Invention
Now, the problem addressed by the present invention was to provide
tablets which, for predetermined hardness, would be distinguished by short
disintegration times which and, 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. 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 so that dosing, storage and
tabletting
problems would be minimized.
It has now been found that the addition of special compounds of anionic
surfactant(s), hydrotrope(s) and optionally carriers to premixes for detergent
tablets leads to tablets which are distinctly more abrasion-resistant and
considerably less friable than the hitherto known tablets. The use of the
additives
mentioned has little or no effect on the fracture hardness. Tabletting
problems
are also avoided by this addition.
In a first embodiment, the present invention relates to an additive for
detergent tablets which may be added to the tablettable premixes in order to
improve the physical properties of the tablets. Accordingly, the present
invention
relates firstly to a composition containing - based on the weight of the
additive -
a) 60 to 95% by weight of anionic surfactant(s),
b) 5 to 40% by weight of hydrotrope(s),
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c) 0 to 35% by weight of carrier material(s).
The composition according to the invention contains one or more anionic
surfactants) as first key constituents. Preferred compositions contain 65 to
90%
by weight, preferably 70 to 85% by weight and more preferably 75 to 80% by
weight, based on the weight of the compound, of anionic surfactant(s).
Suitable anionic surfactants are, for example, those of the sulfonate and
sulfate type. Suitable surfactants of the sulfonate type are preferably C9_~3
alkyl
benzenesulfonates, olefin sulfonates, i.e. mixtures of alkene and
hydroxyalkane
sulfonates, and the disulfonates obtained, for example, from C~2_~$
monoolefins
with an internal or terminal double bond by sulfonation with gaseous sulfur
trioxide and subsequent alkaline or acidic hydrolysis of the sulfonation
products.
Other suitable surfactants of the sulfonate type are the alkane sulfonates
obtained from C~2_~$ alkanes, for example by sulfochlorination or
sulfoxidation
and subsequent hydrolysis or neutralization. The esters of a-sulfofatty acids
(ester sulfonates), for example the a-sulfonated methyl esters of hydrogenated
coconut, palm kernel or tallow acids, are also suitable.
Detailed Description of the Invention
Other suitable anionic surfactants are sulfonated fatty acid glycerol esters.
Fatty acid glycerol esters in the context of the present invention are the
monoesters, diesters and triesters and mixtures thereof which are obtained
where production is carried out by esterification of a monoglycerol with 1 to
3
moles of fatty acid or in the transesterification of triglycerides with 0.3 to
2 moles
of glycerol. Preferred sulfonated fatty acid glycerol esters are the
sulfonation
products of saturated fatty acids containing 6 to 22 carbon atoms, for example
caproic acid, caprylic acid, capric acid, myristic acid, lauric acid, palmitic
acid,
stearic acid or behenic acid.
Preferred alk(en)yl sulfates are the alkali metal salts and, in particular,
the
sodium salts of the sulfuric acid semiesters of C,2_~$ fatty alcohols, for
example
cocofatty alcohol, tallow fatty alcohol, lauryl, myristyl, cetyl or stearyl
alcohol, or
Coo-zo 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
CA 02324070 2000-10-23
petrochemical and which are similar in their degradation behavior to the
corresponding compounds based on oleochemical raw materials. C~2_~6 alkyl
sulfates, C~2_~5 alkyl sulfates and C~4_~5 alkyl sulfates are preferred from
the point
of view of washing technology. Other suitable anionic surfactants are 2,3-
alkyl
5 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
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~2_~a
fatty
alcohols containing 1 to 4 EO, are also suitable. In view of their high
foaming
capacity, they are only used in relatively small quantities, for example in
quantities of 1 to 5% by weight, in dishwashing detergents.
Other suitable anionic surfactants are the salts of alkyl sulfosuccinic acid
which are also known as sulfosuccinates or as sulfosuccinic acid esters and
which represent monoesters and/or diesters of sulfosuccinic acid with
alcohols,
preferably fatty alcohols and, more particularly, ethoxylated fatty alcohols.
Preferred sulfosuccinates contain C8_~$ fatty alcohol residues or mixtures
thereof.
Particularly preferred sulfosuccinates contain a fatty alcohol residue derived
from
ethoxylated fatty alcohols which, considered in isolation, represent nonionic
surfactants (for a description, see below). Of these sulfosuccinates, those of
which the fatty alcohol residues are derived from narrow-range ethoxylated
fatty
alcohols are particularly preferred. Alk(en)yl succinic acid preferably
containing 8
to 18 carbon atoms in the alk(en)yl chain or salts thereof may also be used.
Other suitable anionic surfactants are, in particular, soaps. Suitable soaps
are saturated fatty acid soaps, such as the salts of lauric acid, myristic
acid,
palmitic acid, stearic acid, hydrogenated erucic acid and behenic acid, and
soap
mixtures derived in particular from natural fatty acids, for example coconut,
palm
kernel or tallow acids.
The anionic surfactants, including the soaps, may be present in the form of
their sodium, potassium or ammonium salts and as soluble salts of organic
bases, such as mono-, di- or triethanolamine. The anionic surfactants are
preferably present in the form of their sodium or potassium salts and, more
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preferably, in the form of their sodium salts.
Preferred compositions contain one or more surfactants from the groups of
fatty alcohol sulfates, alkyl benzenesulfonates and/or the soaps as anionic
surfactant(s).
Particularly preferred compositions according to the invention are
characterized in that they contain the alkali metal salts and preferably the
sodium
salts of C9_~3 alkyl benzenesulfonic acids as anionic surfactant.
Alkyl benzenesulfonates as high-performance anionic surfactants have
been known since the nineteen thirties. At that time, alkyl benzenes were
produced by monochlorination of Kogasin fractions and subsequent Friedel
Crafts alkylation, sulfonated with oleum and neutralized with sodium
hydroxide.
At the beginning of the fifties, alkyl benzenesulfonates were produced by
tetramerizing propylene to form branched a-dodecylene and reacting the product
in a Friedel-Crafts reaction using aluminium trichloride or hydrogen fluoride
to
form tetrapropylene benzene which was then sulfonated and neutralized. This
economic method of producing tetrapropylene benzene sulfonates (TPS) led to
the breakthrough of this class of surfactants which subsequently displaced
soaps
as the main surfactant in detergents.
In view of the biological non-degradability of TPS, new alkyl
benzenesulfonates distinguished by improved ecological behavior had to be
produced. These requirements are satisfied by linear alkyl benzenesulfonates
which, today, are virtually the only alkyl benzenesulfonates in production and
which are referred to in short by the initials ABS.
Linear alkyl benzenesulfonates are prepared from linear alkyl benzenes
which in turn can be obtained from linear olefins. To this end, petroleum
fractions
are separated using molecular sieves into the n-paraffins with the requisite
purity
and dehydrogenated to the n-olefins, both a- and i-olefins being obtained. The
olefins thus obtained are then reacted with benzene in the presence of acidic
catalysts to form the alkyl benzenes, the choice of the Friedel-Crafts
catalyst
having an influence on the isomer distribution of the linear alkyl benzenes
formed. Where aluminium trichloride is used, the content of the 2-phenyl
isomers
in the mixture with the 3-, 4-, 5- and other isomers is approximately 30% by
weight. If, by contrast, hydrogen fluoride is used as the catalyst, the 2-
phenyl
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isomer content can be reduced to around 20% by weight. Finally, the
sulfonation
of the linear alkyl benzenes is now carried out on an industrial scale with
oleum,
sulfuric acid or gaseous sulfur trioxide, gaseous sulfur trioxide having by
far the
greatest importance. Special falling-film or tube-bundle reactors are used for
the
sulfonation process and give as the end product a 97% by weight alkyl
benzenesulfonic acid (ABSA) which may be marketed as such or neutralized with
NaOH to form water-containing ABS pastes with active substance contents of
around 60% by weight which are then marketed.
Various salts, i.e. alkyl benzene sulfonates, can be obtained from the
ABSA, depending on the choice of the neutralizing agent. For reasons of
economy, it is preferred to produce and use the alkali metal salts of ABSA,
preferably the sodium salts. The sodium salts correspond to general formula I:
H
H3C-(CH2)x-C-(CH2)y-CH3
S03Na
(I),
in which the sum of x and y is normally between 5 and 13. According to the
invention, preferred compounds are characterized in that they contain the
alkali
metal salts and preferably the sodium salts of C$_~6 and preferably C9_~3
alkyl
benzenesulfonic acids derived from alkyl benzenes having a tetralin content of
less than 5% by weight, based on the alkyl benzene.
Another preferred embodiment is characterized by the use in the
compounds according to the invention of alkyl benzenesulfonates of which the
alkyl benzenes have been produced by the HF process, so that compounds
containing the alkali metal salts and preferably the sodium salts of C8_~6,
preferably C9_~3 alkyl benzene sulfonic acids which have a 2-phenyl isomer
content below 22% by weight, based on the alkyl benzenesulfonic acid, are
preferred.
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The compounds according to the invention contain one or more
hydrotrope(s) as a second key constituent. Although they are not themselves
solvents, these substances have the effect that poorly soluble substances can
be
better dissolved in water in their presence. Preferred compounds contain,
based
on their weight, from 6 to 35% by weight, preferably from 7.5 to 30% by
weight,
more preferably from 10 to 25% by weight and most preferably from 12.5 to 20%
by weight of hydrotrope(s).
Certain hydrotropes are preferably used for the purposes of the invention.
These preferred hydrotropes belong to the group of short-chain alkyl
benzenesulfonates of which the alkyl groups contain in all at most 6 carbon
atoms, short-chain carboxylic acids and salts thereof, sugars and highly water-
soluble covalent compounds.
Preferred compounds contain aromatic sulfonates corresponding to
formula II:
x+
~ Ks
(II)
in which each of the substituents R~, R2, R3, R4 and R5 independently of one
another is selected from H or a C~_5 alkyl or alkenyl group and X is a cation,
as
hydrotrope.
Preferred substituents R~, R2, R3, R4 and R5 independently of one another
are selected from H or a methyl, ethyl, n-propyl, isopropyl, n-butyl,
isobutyl,
tert.butyl, n-pentyl, isopentyl or neopentyl group. In general, at least three
of the
substituents R' to R5 are hydrogen atoms, aromatic sulfonates in which three
or
four substituents at the aromatic ring are hydrogen atoms being preferred. The
remaining substituent or the remaining two substituents may occupy any
position
to the sulfonate group and to one another. In the case of monosubstituted
compounds corresponding to formula I, R3 is preferably an alkyl group while
R~,
R2, R4 and RS preferably represent H (para substitution).
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According to the invention, particularly preferred aromatic sulfonates are
toluene, cumene and xylene sulfonate.
Of the two commercially obtainable toluenesulfonates (ortho- and para-
toluenesulfonate), the para-isomer is preferred for the purposes of the
invention.
Among the cumemesulfonates, too, the para-isopropyl benzenesulfonate is the
preferred compound. Since, on an industrial scale, xylene is mostly used as an
isomer mixture, even the commercially obtainable xylenesulfonate is a mixture
of
several compounds resulting from the sulfonation of ortho, meta- and para-
xylene. These isomer mixture are dominated by those compounds in which the
following substituents in general formula I are methyl groups (all other
substituents stand for H); R~ and R2, R~ and R4, R~ and R3 and R~ and R5. In
the
case of the xylenesulfonates, therefore, at least one methyl group is
preferably in
the ortho-position to the sulfonate group.
X in general formula I stands for a cation, for example an alkali metal
cation, such as sodium or potassium. However, X may also stand for the charge-
equivalent portion of a polyvalent cation, for example for Mg2+/2 or AI3+/3.
Of the
cations mentioned, sodium is preferred.
Particularly preferred compounds are characterized in that, based on their
weight, they contain 6 to 35% by weight, preferably 7.5 to 30% by weight, more
preferably 10 to 25% by weight and most preferably 12.5 to 20% by weight of
sodium para-toluenesulfonate (R3 = CH3, R~ = RZ = R4 = R5 = H, X = Na).
Other preferred compounds according to the invention contain, based on
their weight, 6 to 35% by weight, preferably 7.5 to 30% by weight, more
preferably 10 to 25% by weight and most preferably 12.5 to 20% by weight of
sodium para-cumenesulfonate (R3 = CH(CH3)2, R' = R2 = R4 = R5 = H, X = Na).
According to the invention, other preferred hydrotropes are carboxylic
acids and salts thereof. In this case, compounds containing one or more mono-,
di-, tri- or oligocarboxylic acids and/or salts thereof as hydrotrope are
preferred,
fumaric acid, L(+) ascorbic acid, L-(-) malic acid, malefic acid, malonic
acid, DL
malefic acid, citric acid and alkali metal salts thereof being particularly
preferred.
Sugars may also be used in the compounds according to the invention.
Preferred compounds contain one or more sugars as hydrotrope, lactose, L(-)
sorbose, D(+) galactose, D(+) glucose, sucrose, D(+) mannose, melibiose, D(-)
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fructose being particularly preferred.
Last but not least, readily water-soluble, non-salt-like compounds are
particularly suitable as hydrotropes for the purposes of the invention.
Compounds containing one or more covalent compounds with a solubility in
5 water of more than 200 g per liter water at 20°C, preferably more
than 400 g per
liter water at 20°C and, more preferably, more than 700 g per liter
water at 20°C
as hydrotrope, urea and N-methyl acetamide being particularly preferred, are
also
preferred.
Besides anionic surfactants) and hydrotrope(s), the compounds according
10 to the invention may contain other ingredients. Depending on the nature and
quantity of the two compulsory constituents, carrier materials) may have to be
incorporated in the compounds in order to improve their processability and
stability in storage. Compounds according to the invention containing - based
on
their weight - 1 to 30% by weight, preferably 2.5 to 20% by weight, more
preferably 4 to 15% by weight and most preferably 5 to 10% by weight of
carrier
materials) are preferred.
Preferred carrier materials are in particular builders, of which the
silicates,
carbonates and zeolites have proved to be suitable. Silicas and sulfates are
also
particularly suitable carrier materials. Alkali metal silicates and alkali
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 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.
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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 mz/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 builders, more particularly 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 compounds.
Particularly preferred compounds according to the invention are
characterized in that they contain one or more materials from the group
consisting of sodium sulfate, sodium carbonate, sodium hydrogen carbonate
and/or from the groups of sodium silicates and zeolites as carrier material.
The present invention also relates to detergent tablets containing the
compounds according to the invention, specifically detergent tablets of
compacted particulate detergent, which are characterized in that they contain
a
compound according to the invention.
The compound according to the invention is preferably used in quantities
below 20% by weight. Preferred detergent tablets are characterized in that
they
contain the compound in quantities of 0.1 to 20% by weight, preferably 0.25 to
15% by weight, more preferably 0.5 to 10% by weight and most preferably 1 to
5% by weight, based on the weight of the tablet.
Besides the 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.
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Disintegration aids are mentioned as further additives which are not normally
used in detergents, but which can have advantageous effects in tablets.
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" (8th
Edition, 1987, pages 182-184), tablet disintegrators or disintegration
accelerators are auxiliaries which promote the rapid disintegration of tablets
in
water or gastric juices and the release of the pharmaceuticals in an
absorbable
form.
These substances, which are also known as "disintegrators" by virtue of
their effect, are capable of undergoing an increase in volume on contact with
water so that, on the one hand, their own volume is increased (swelling) and,
on
the other hand, a pressure can be generated through the release of gases which
causes the tablet to disintegrate into relatively small particles. Well-known
disintegrators are, for example, carbonate/citric acid systems, although other
organic acids may also be used. Swelling disintegration aids are, for example,
synthetic polymers, such as polyvinyl pyrrolidone (PVP), or natural polymers
and
modified natural substances, such as cellulose and starch and derivatives
thereof, alginates or casein derivatives.
Preferred detergent tablets contain 0.5 to 10% by weight, preferably 3 to
7% by weight and more preferably 4 to 6% by weight of one or more
disintegration aids, based on the weight of the tablet.
According to the invention, preferred disintegrators are cellulose-based
disintegrators, so that preferred detergent tablets contain a cellulose-based
disintegrator in quantities of 0.5 to 10% by weight, preferably 3 to 7% by
weight
and more preferably 4 to 6% by weight. Pure cellulose has the formal empirical
composition (C6H~o05)~ and, formally, is a ~-1,4-polyacetal of cellobiose
which, in
turn, is made up of 2 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,
CA 02324070 2000-10-23
13
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
disintegrator. In one particularly preferred embodiment, pure cellulose free
from
cellulose derivatives is used as the cellulose-based disintegrator.
The cellulose used as disintegration aid is preferably not used in fine
particle form, but is converted into a coarser form, for example by
granulation or
compacting, before it is added to and mixed with the premixes to be tabletted.
Detergent tablets which contain granular or optionally co-granulated
disintegrators are described in German patent applications DE 197 09 991
(Stefan Herzog) and DE 197 10 254 (Henkel) and in International patent
application WO 98140463 (Henkel). Further particulars of the production of
granulated, compacted or co-granulated cellulose disintegrators can also be
found in these patent applications. The particle sizes of such disintegration
aids
is mostly above 200 Nm, at least 90% by weight of the particles being between
300 and 1600 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
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14
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.
Preferred detergent tablets according to the invention additionally contain
a disintegration aid, preferably a cellulose-based disintegration aid,
preferably in
granular, cogranulated or compacted form, in quantities of 0.5 to 10% by
weight,
preferably 3 to 7% by weight and more preferably 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 NaMSiX02X+~A y H20, where M is sodium or hydrogen, x is a number of
1.9 to 4 and y is a number of 0 to 20, preferred values for x being 2, 3 or 4.
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 ~- and s-sodium
disilicates Na2Si205A y HZO are particularly preferred.
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 ~amorphous0 is also understood to encompass ~X-ray amorphous. In
other words, the silicates do not produce any of the sharp X-ray reflexes
typical of
crystalline substances in X-ray diffraction experiments, but at best one or
more
maxima of the scattered X-radiation which have a width of several degrees of
the
diffraction angle. However, particularly good builder properties may even be
achieved where the silicate particles produce crooked or even sharp
diffraction
maxima in electron diffraction experiments. This may be interpreted to mean
that
CA 02324070 2000-10-23
the products have microcrystalline regions between 10 and a few hundred nm in
size, values of up to at most 50 nm and, more particularly, up to at most 20
nm
being preferred. So-called X-ray amorphous silicates such as these, which also
dissolve with delay in relation to conventional waterglasses, are described
for
5 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.
The finely crystalline, synthetic zeolite containing bound water used in
accordance with the invention is preferably zeolite A and/or zeolite P.
Zeolite
10 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-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
15 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 ~m (volume distribution, as measured
by the Coulter Counter Method) and contain preferably 18 to 22% by weight and
more preferably 20 to 22% by weight of bound water.
The generally known phosphates may of course also be used as builders
providing their use should not be avoided on ecological grounds. Among the
large number of commercially available phosphates, alkali 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
CA 02324070 2000-10-23
16
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, Na2H2P20~) 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 by neutralization of phosphoric acid with soda
solution using phenolphthalein as indicator. Dipotassium hydrogen phosphate
(secondary or dibasic potassium phosphate), K2HP04, 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% P205). Trisodium phosphate is readily
soluble in water through an alkaline reaction and is prepared by concentrating
a
CA 02324070 2000-10-23
17
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 3,
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), K4P20~, exists in the form of
the trihydrate and is a colorless hygroscopic powder with a density of 2.33
gcm-3
which is 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
CA 02324070 2000-10-23
18
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, K5P30~o (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
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,
CA 02324070 2000-10-23
19
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.
The molecular weights mentioned in this specification for polymeric
polycarboxylates are weight-average molecular weights MW of the particular
acid
form which, basically, were determined by gel permeation chromatography (GPC)
using a UV detector. The measurement was carried out against an external
polyacrylic acid standard which provides realistic molecular weight values by
virtue of its structural similarity to the polymers investigated. These values
differ
distinctly from the molecular weights measured against polystyrene sulfonic
acids
as standard. The molecular weights measured against polystyrene sulfonic acids
are generally 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 g/mole and, more particularly, 3,000
to 5,000 g/mole.
Also suitable are copolymeric polycarboxylates, particularly those of acrylic
acid with methacrylic acid and those of acrylic acid or methacrylic acid with
malefic acid. Acrylic acid/maleic acid copolymers containing 50 to 90% by
weight
of acrylic acid and 50 to 10% by weight of malefic acid have proved to be
particularly suitable. Their relative molecular weights, based on the free
acids,
are generally in the range from 2,000 to 70,000 g/mole, preferably in the
range
from 20,000 to 50,000 g/mole and more preferably in the range from 30,000 to
40,000 g/mole.
The (co)polymeric polycarboxylates may be used either in powder form or
in the form of an aqueous solution. The content of (co)polymeric
CA 02324070 2000-10-23
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
5 for example, as monomer.
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
10 derivatives 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 also have a bleach-stabilizing efFect in
addition to their co-builder properties.
15 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, terephthalaldehyde and mixtures thereof and
from polyol carboxylic acids, such as gluconic acid and/or glucoheptonic acid.
20 Other suitable organic builders are dextrins, for example oligomers or
polymers of carbohydrates which may be obtained by partial hydrolysis of
starches. The hydrolysis may be carried out by standard methods, for example
acid- or enzyme-catalyzed methods. The end products are preferably hydrolysis
products with average molecular weights of 400 to 500,000 g/mole. A
polysaccharide with a dextrose equivalent (DE) of 0.5 to 40 and, more
particularly, 2 to 30 is preferred, the DE being an accepted measure of the
reducing effect of a polysaccharide by comparison with dextrose which has a DE
of 100. Both maltodextrins with a DE of 3 to 20 and dry glucose sirups with a
DE
of 20 to 37 and also so-called yellow dextrins and white dextrins with
relatively
high molecular weights of 2,000 to 30,000 g/mole may be used.
The oxidized derivatives of such dextrins are their reaction products with
oxidizing agents which are capable of oxidizing at least one alcohol function
of
the saccharide ring to the carboxylic acid function. An oxidized
oligosaccharide is
CA 02324070 2000-10-23
21
also suitable. A product oxidized at C6 of the saccharide ring can be
particularly
advantageous.
Other suitable co-builders are oxydisuccinates and other derivatives of
disuccinates, preferably ethylenediamine disuccinate. Ethylenediamine-N,N'-
disuccinate (EDDS) is preferably used in the form of its sodium or magnesium
salts. Glycerol disuccinates and glycerol trisuccinates are also 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.
Another class of substances with co-builder properties are the
phosphonates, more particularly hydroxyalkane and aminoalkane phosphonates.
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). 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
CA 02324070 2000-10-23
22
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).
Besides the anionic surfactant present in the compounds, the detergent
tablets according to the invention may contain other anionic surfactants.
Nonionic, cationic and zwitterionic surfactants may also be used.
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.
Preferred nonionic surfactants are alkoxylated, advantageously
ethoxylated, more especially primary alcohols preferably containing 8 to 18
carbon atoms and, on average, 1 to 12 moles of ethylene oxide (EO) per mole of
alcohol, in which the alcohol component may be linear or, preferably, methyl-
branched in the 2-position or may contain linear and methyl-branched residues
in
the form of the mixtures typically present in oxoalcohol residues. However,
alcohol ethoxylates containing linear residues of alcohols of native origin
with 12
to 18 carbon atoms, for example coconut, palm, tallow or oleyl alcohol, and on
average 2 to 8 EO per mole of alcohol are particularly preferred. Preferred
ethoxylated alcohols include, for example, C~2_~4 alcohols containing 3 EO or
4
EO, C9_» alcohol containing 7 EO, C~3-~5 alcohols containing 3 EO, 5 EO, 7 EO
or 8 EO, C~2_~$ 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_~8 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
CA 02324070 2000-10-23
23
containing more than 12 EO may also be used, examples including tallow fatty
alcohol containing 14 EO, 25 EO, 30 EO or 40 EO.
Other nonionic surfactants which may be used are alkyl glycosides
corresponding to the general formula RO(G)X where R is a primary linear or 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; x
preferably has a value of 1.2 to 1.4.
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
particularly fatty acid methyl esters.
Nonionic surfactants of the amine oxide type, for example N-cocoalkyl-
N,N-dimethylamine oxide and N-tallowalkyl-N,N-dihydroxyethylamine 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] (I I I)
in which RCO is an aliphatic acyl group containing 6 to 22 carbon atoms, R' is
hydrogen, an alkyl or hydroxyalkyl group containing 1 to 4 carbon atoms and
[Z]
is a linear or branched polyhydroxyalkyl group containing 3 to 10 carbon atoms
and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid amides are known
substances which may normally be obtained by reductive amination of a reducing
sugar with ammonia, an alkylamine or an alkanolamine and subsequent acylation
with a fatty acid, a fatty acid alkyl ester or a fatty acid chloride.
CA 02324070 2000-10-23
24
The group of polyhydroxyfatty acid amides also includes compounds
corresponding to formula (V):
R'-O-R2
R-CO-N-[Z] (IV)
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 polyhydroxyalkyl 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.
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 characterized 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 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
CA 02324070 2000-10-23
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
5 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
10 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
15 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,
20 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, for example, sodium
percarbonate, peroxypyrophosphates, citrate perhydrates and H202-yielding
25 peracidic salts or peracids, such as perbenzoates, peroxophthalates,
diperazelaic
acid, phthaloiminoperacid or diperdodecane dioic acid. Where bleaching agents
are used, it is again 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,
bleaching agents from the group of organic bleaches may also be used. Typical
organic bleaching agents are diacyl peroxides, such as dibenzoyl peroxide for
CA 02324070 2000-10-23
26
example. Other typical organic bleaching agents are the peroxy acids, of which
alkyl peroxy acids and aryl peroxy acids are particularly mentioned as
examples.
Preferred representatives are (a) peroxybenzoic acid and ring-substituted
derivatives thereof, such as alkyl peroxybenzoic acids, but also peroxy-a-
naphthoic acid and magnesium monoperphthalate, (b) aliphatic or substituted
aliphatic peroxy acids, such as peroxylauric acid, peroxystearic acid, s-
phthalimidoperoxycaproic acid [phthaloiminoperoxyhexanoic acid (PAP)], o-
carboxybenzamidoperoxycaproic acid, N-nonenylamidoperadipic acid and N-
nonenylamidopersuccinates, and (c) aliphatic and araliphatic
peroxydicarboxylic
acids, such as 1,12-diperoxycarboxylic acid, 1,9-diperoxyazelaic acid,
diperoxysebacic acid, diperoxybrassylic acid, diperoxyphthalic acids, 2-
decyldiperoxybutane-1,4-dioic acid, N,N-terephthaloyl-di(6-aminopercaproic
acid).
Other suitable bleaching agents in dishwasher tablets are chlorine- and
bromine-releasing substances. Suitable chlorine- or bromine-releasing
materials
are, for example, heterocyclic N-bromamides and N-chloramides, for example
trichloroisocyanuric acid, tribromoisocyanuric acid, dibromoisocyanuric acid
and/or dichloroisocyanuric acid (DICA) and/or salts thereof with cations, such
as
potassium and sodium. Hydantoin compounds, such as 1,3-dichloro-5,5-dimethyl
hydantoin, are also suitable.
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
CA 02324070 2000-10-23
27
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-d ihyd rofu ran.
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 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
CA 02324070 2000-10-23
28
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 cellobio-
hydrolases, endoglucanases and ~i-glucosidases, which are also known as
cellobiases, and mixtures thereof. Since the various cellulase types differ in
their
CMCase and avicelase activities, the desired activities can be established by
mixing the cellulases in the appropriate ratios.
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.
CA 02324070 2000-10-23
29
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 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 and 1 to 15% by weight of hydroxypropoxyl groups,
CA 02324070 2000-10-23
based on the nonionic cellulose ether, and the polymers of phthalic acid
and/or
terephthalic acid known from the prior art or derivatives thereof, more
particularly
polymers of ethylene terephthalates and/or polyethylene glycol terephthalates
or
anionically and/or nonionically modified derivatives thereof. Of these, the
5 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
brighteners are,
for example, salts of 4,4'-bis-(2-anilino-4-morpholino-1,3,5-triazinyl-6-
amino)-
10 stilbene-2,2'-disulfonic acid or compounds of similar composition which
contain a
diethanolamino group, a methylamino group, an anilino group or a 2-
methoxyethylamino group instead of the morpholino group. Brighteners of the
substituted diphenyl styryl type, for example alkali metal salts of 4,4'-bis-
(2-
sulfostyryl)-diphenyl, 4,4'-bis-(4-chloro-3-sulfostyryl)-diphenyl or 4-(4-
15 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 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
20 with a visually and sensorially "typical and unmistakable" product.
Suitable
perfume oils or perfumes include individual perfume compounds, for example
synthetic products of the ester, ether, aldehyde, ketone, alcohol and
hydrocarbon
type. Perfume compounds of the ester type are, for example, benzyl acetate,
phenoxyethyl isobutyrate, p-tert.butyl cyclohexyl acetate, linalyl acetate,
dimethyl
25 benzyl carbinyl acetate, phenyl ethyl acetate, linalyl benzoate, benzyl
formate,
ethyl methyl phenyl glycinate, allyl cyclohexyl propionate, styrallyl
propionate and
benzyl salicylate. The ethers include, for example, benzyl ethyl ether; the
aldehydes include, for example, the linear alkanals containing 8 to 18 carbon
atoms, citral, citronellal, citronellyloxyacetaldehyde, cyclamen aldehyde,
30 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
CA 02324070 2000-10-23
31
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 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
CA 02324070 2000-10-23
32
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 compounds
according to the invention.
Multiphase tablets may also be produced in accordance with the invention,
two-layer tablets being the most simple embodiment of a multiphase tablet.
Accordingly, the present invention also relates to a process for the
production of
multiphase detergent tablets by tabletting several particulate premixes in
known
manner, characterized in that at least one of the premixes contains one or
more
compounds according to the invention.
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. For example, preferred
processes according to the invention are characterized in that the premixes)
contains) compounds) in quantities of 0.1 to 20% by weight, preferably in
quantities of 0.25 to 15% by weight, more preferably in quantities of 0.5 to
10%
by weight and most preferably in quantities of 1 to 5% by weight, based on the
weight of the premix.
In preferred variants of the process, the compounds also satisfy certain
particle size criteria. Thus, preferred processes according to the invention
are
characterized in that the compounds) has/have a mean particle size below 1,000
Nm, preferably below 850 Nm and more preferably below 700 pm. In a
particularly preferred embodiment, the compounds) is/are free from particles
larger than 1200 Nm in size, preferably free from particles larger than 1000
Nm in
size and more preferably free from particles larger than 900 Nm in size.
Fines are also preferably removed from the compounds to be used in
accordance with the invention before tabletting. Preferred processes according
to the invention are characterized in that the compounds) is/are free from
CA 02324070 2000-10-23
33
particles below 100 pm in size, preferably free from particles below 200 Nm in
size and more preferably free from particles below 300 Nm in size.
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, at least one particulate premix additionally contains surfactant-
containing granules) and 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 pm.
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. 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 premix is preferably "powdered" with fine-
particle zeolite, zeolites of the faujasite type being preferred. In the
context of the
CA 02324070 2000-10-23
34
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
York/London/Sydney/Toronto, 1974, page 92). Besides zeolite X, therefore,
zeolite Y and faujasite and mixtures of these compounds may also be used, pure
zeolite X being preferred. 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 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 components subsequently
incorporated being a faujasite zeolite with particle sizes below 100 Nm,
preferably
below 10 Nm and more preferably below 5 pm 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.
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,
disintegration
aids, enzymes, pH regulators, perfumes, perfume carriers, fluorescers, dyes,
foam inhibitors, silicone oils, redeposition inhibitors, optical brighteners,
discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors.
These
substances are described in the foregoing.
The present invention also relates to a process for the production of
detergent tablets which comprises the steps of
a) producing a compound of
aa) 60 to 95% by weight of anionic surfactant(s),
ab) 5 to 40% by weight of hydrotrope(s) and
ac) 0 to 35% by weight of carrier material(s),
b) producing surfactant-containing granules,
c) mixing the compound from step a) and the granules from step b) with other
ingredients of detergents and
CA 02324070 2000-10-23
d) compressing the premix formed in step c) to form tablets or regions
thereof.
So far as the choice of suitable machines and process parameters for
steps a) and b) are concerned, the expert may resort to machines and apparatus
5 known from the literature and to the technical operations described, for
example,
in W. Pietsch, "Size Enlargement by Agglomeration" Wiley, 1991, and the
literature cited therein. The following observations represent only a small
part of
the range of possibilities available to the expert for carrying out both steps
of the
process according to the invention.
10 The compounds according to the invention may be carried out by
granulation or forming processes known per se, granulation of the solid
constituents initially introduced into the mixer with the liquid constituents
being
preferred. This variant of process step a) is appropriate, for example, when
solid
neutralizing agent is introduced first and the alkyl benzenesulfonic acid is
added
15 to the bed of solids which also contains the hydrotropes. If only solids
are to be
processed, as is the case with the processing of alkyl benzenesulfonates, such
processes as roll compacting and pelleting (ring die presses) are appropriate.
The production of surfactant granules {step b) of the process according to
the invention} may be carried out in various conventional mixers and
granulators.
20 Mixers suitable for carrying out step b) of the process according to the
invention
are, for example, Series R or RV Eirich~ mixers (trademarks of Maschinenfabrik
Gustav Eirich, Hardheim), the Schugi~ Flexomix, Fukae~ FS-G mixers
(trademarks of Fukae Powtech, Kogyo Co., Japan}, Lodige~ FM, KM and CB
mixers (trademarks of Lodige Maschinenbau GmbH, Paderborn) or Series T or K-
25 T Drais~ mixers (trademarks of Drais-Werke GmbH, Mannheim). Some
preferred embodiments of step b) of the process according to the invention are
described in the following.
For example, it is possible and preferred to carry out process step b) in a
low-speed mixer/granulator at peripheral speeds of the tools of 2 m/s to 7
m/s.
30 Alternatively, in preferred variants of the process, step b) may be carried
out in a high-speed mixer/granulator at peripheral speeds of 8 m/s to 35 m/s.
Whereas the two process variants described above each use a mixer, it is
also possible in accordance with the invention to combine two mixers with one
CA 02324070 2000-10-23
36
another. For example, preferred processes are characterized in that, in step
a), a
liquid granulation aid is added to an agitated bed of solids in a first low-
speed
mixer/granulator, 40 to 100% by weight, based on the total quantity of
constituents used, of the solid and liquid constituents being pregranulated
and
the "pregranules" from the first process step optionally being mixed with the
remaining solid and/or liquid constituents and converted into granules in a
second
high-speed mixer/ granulator. In this variant of the process, a granulation
aid is
added to a bed of solids in a first mixer/granulator and the mixture is
pregranulated. The composition of the granulation aid and of the bed of solids
introduced into the first mixer are selected so that 40 to 100% by weight,
preferably 50 to 90% by weight and more preferably 60 to 80% by weight of the
solid and liquid constituents, based on the total quantity of constituents
used, are
contained in the "pregranules". These "pregranules" are then mixed with more
solids in the second mixer and granulated in the presence of more liquid
components to form the final surfactant granules.
According to the invention, the above-mentioned sequence of low-
speed/high-speed mixers may also be reversed, resulting in a process according
to the invention in which the liquid granulation aid is added to an agitated
bed of
solids in a first high-speed mixer/granulator, 40 to 100% by weight, based on
the
total quantity of constituents used, of the solid and liquid constituents
being
pregranulated and the pregranules from the first process step optionally being
mixed with the remaining solid and/or liquid constituents and converted into
granules in a second low-speed mixer/granulator.
All the variants of the process according to the invention described in the
foregoing may be carried out either in batches or continuously. High-speed
mixer/granulators are used in some of the above-described variants of step a)
of
the process according to the invention. In one particularly preferred
embodiment
of the invention, a mixer comprising both a mixing unit and a size-reducing
unit is
used as a high-speed mixer, the mixing shaft being driven at peripheral speeds
of
50 to 150 r.p.m. and preferably 60 to 80 r.p.m. and the shaft of the size-
reducing
unit being driven at rotational speeds of 500 to 5000 r.p.m. and preferably
1000
to 3000 r. p. m.
CA 02324070 2000-10-23
37
Preferred granulation processes for the production of mixer granules are
carried out in mixer granulators in which certain parts of the mixer or the
entire
mixer is/are heated to temperatures at least 20°C above the temperature
which
the materials to be granulated have at the beginning of the granulation
process.
Accordingly, if solids which have been stored at 20°C and which enter
the mixer
with this temperature are granulated, certain parts of the mixer or the mixer
as a
whole preferably have/has a temperature of at least 40°C. Overall,
however, a
temperature of 120°C for the mixer parts or for the mixer as a whole
should not
be exceeded. If only certain parts of the mixer are heated to the temperatures
mentioned, the parts in question are preferably the mixer walls or the mixer
tools.
The mixer walls can be brought to the required temperature by a heatable
jacket
while the mixer tools can be brought to the required temperature by built-in
heating elements.
In the production of surfactant-containing granules in completely or partly
heated mixers, it is also preferred to use non-aqueous granulation aids, more
particularly nonionic surfactants, which have a melting point of 20 to
50°C. The
preferred granulation process described above enables the bulk density of the
surfactant granules to be increased and, at the same time, unwanted caking on
the walls of the mixer to be distinctly reduced. The use of surfactant
granules
produced in this way in tablettable premixes leads to detergent tablets which
are
distinguished from mixtures containing conventionally produced granules by a
further reduced disintegration time.
The production of the surfactant granules {step b) of the process according
to the invention} can also be carried out by press agglomeration processes,
the
products often being referred to as press granules. Their production {in step
b) of
the process according to the invention} is carried out by press agglomeration
processes, preferably by extrusion, roller compacting or pelleting.
In all the press agglomeration processes mentioned, the premix is
compacted and plasticized under pressure and under the effect of shear forces,
homogenized and then discharged from the machines via a forming/ shaping
stage.
In a preferred embodiment of process step b), the premix is preferably
delivered continuously to a planetary roll extruder or to a twin-screw
extruder with
CA 02324070 2000-10-23
38
co-rotating or contra-rotating screws, of which the barrel and the
extruder/granulation head may be heated to the predetermined extrusion
temperature. Under the shearing effect of the extruder screws, the premix is
compacted under pressure (preferably at least 25 bar or - with extremely high
throughputs - even lower, depending on the machine used), plasticized,
extruded
in the form of fine strands through the multiple-bore die in the extruder head
and,
finally, the extrudate is chopped by means of a rotating blade into preferably
substantially spherical or cylindrical granules. The bore diameter of the
multiple-
bore extrusion die and the length to which the extruded strands are cut are
adapted to the size selected for the granules. In this embodiment, it is
possible to
produce granules with a substantially uniform predetermined particle size, the
absolute particle sizes being adaptable to the particular application
envisaged.
The particle diameters described in the foregoing are generally preferred. In
one
important embodiment, the length-to-diameter ratio of the primary granules
formed by cutting the extruded strands is between about 1:1 and about 3:1. In
another preferred embodiment, the still plastic primary granules are subjected
to
another shaping or forming step in which the edges present on the crude
extrudate are rounded off so that spherical or substantially spherical
extrudate
granules can ultimately be obtained. If desired, small quantities of dry
powder,
for example zeolite powder, such as zeolite NaA powder, may be used in this
step which may be carried out in commercially available spheronizers. It is
important to ensure that only small quantities of fines are formed in this
step.
Alternatively, extrusion/compression can also be carried out in low-pressure
extruders, in a Kahl press or in a Bextruder.
As in the extrusion process, it is preferred in the other production
processes to subject the primary granules/compactates formed to another
shaping process step, more particularly to spheronizing, so that spherical or
substantially spherical (bead-like) granules can be obtained.
In another preferred embodiment of the present invention, step b) of the
process the process according to the invention is carried out by roll
compacting.
In this process, the premix for the press granules is introduced between two
rollers - either smooth or provided with depressions of defined shape - and
rolled
under pressure between the two rollers to form a sheet-like compactate. The
CA 02324070 2000-10-23
39
rollers exert a high linear pressure on the premix and may be additionally
heated
or cooled as required. Where smooth rollers are used, smooth untextured
compactate sheets are obtained. By contrast, where textured rollers are used,
correspondingly textured compactates, in which for example certain shapes can
be imposed in advance on the subsequent press granules, can be produced.
The sheet-like compactate is then broken up into smaller pieces by a chopping
and size-reducing process and can thus be processed to granules which can be
further refined by further surface treatment processes, more particularly
converted into a substantially spherical shape.
In another preferred embodiment of the present invention, step b) of the
process according to the invention is carried out by pelleting. In this
process, the
premix for the press granules is applied to a perforated surface and is forced
through the perforations by a pressure roller. In conventional pellet presses,
the
premix is compacted under pressure, plasticized, forced through a perforated
surface in the form of fine strands by means of a rotating roller and,
finally, is
size-reduced to granules by a cutting unit. The pressure roller and the
perforated
die may assume many different forms. For example, flat perforated plates are
used, as are concave or convex ring dies through which the material is pressed
by one or more pressure rollers. In perforated-plate presses, the pressure
rollers
may also be conical in shape. In ring die presses, the dies and pressure
rollers)
may rotate in the same direction or in opposite directions. A press suitable
for
carrying out the process according to the invention is described, for example,
in
DE-OS 38 16 842 (Schluter GmbH). The ring die press disclosed in this
document consists of a rotating ring die permeated by pressure bores and at
least one pressure roller operatively connected to the inner surface thereof
which
presses the material delivered to the die space through the pressure bores
into a
discharge unit. The ring die and pressure roller are designed to be driven in
the
same direction which reduces the shear load applied to the premix and hence
the
increase in temperature which it undergoes. However, the pelleting process may
of course also be carried out with heatable or coolable rollers to enable the
premix to be adjusted to a required temperature.
The tablets according to the invention are produced by first dry-mixing the
ingredients - which may be completely or partly pregranulated - and then
CA 02324070 2000-10-23
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
5 phases, namely dosing, 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
10 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
15 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
20 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,
25 crystallographic effects, cooling, etc.).
The tabletting process is carried out in commercially available tablet
presses which, in principle, may be equipped with single or double punches. In
the latter case, not only is the top punch used to build up pressure, the
bottom
punch also moves towards the top punch during the tabletting process while the
30 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
CA 02324070 2000-10-23
41
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 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.
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42
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 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
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43
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, in particular,
cylindrical
forms of circular or oval cross-section. This last embodiment encompasses
shapes from tablets to compact cylinders with a height-to-diameter ratio of
more
than 1.
The portioned pressings may be formed as separate individual elements
which correspond to a predetermined dose of the detergent. However, it is also
possible to form pressings which combine several such units in a single
pressing,
smaller portioned units being easy to break off in particular through the
provision
of predetermined weak spots. For the use of laundry detergents in machines of
the standard European type with horizontally arranged mechanics, it can be of
advantage to produce the portioned pressings as cylindrical or square tablets,
preferably with a diameter-to-height ratio of about 0.5:2 to 2:0.5.
Commercially
available hydraulic presses, eccentric presses and rotary presses are
particularly
suitable for the production of pressings such as these.
The three-dimensional form of another embodiment of the tablets
according to the invention is adapted in its dimensions to the dispensing
compartment of commercially available domestic washing machines, so that the
tablets can be introduced directly, i.e. without a dosing aid, into the
dispensing
compartment where they dissolve on contact with water. However, it is of
course
readily possible - and preferred in accordance with the present invention - to
use
the detergent tablets in conjunction with a dosing aid.
Another preferred tablet which can be produced has a plate-like or slab-
like structure with alternately thick long segments and thin short segments,
so
that individual segments can be broken off from this "bar" at the
predetermined
weak spots, which the short thin segments represent, and introduced into the
CA 02324070 2000-10-23
44
machine. This "bar" principle can also be embodied in other geometric forms,
for
example vertical triangles which are only joined to one another at one of
their
longitudinal sides.
In another possible embodiment, however, the various components are
not compressed to form a single tablet, instead the tablets obtained comprise
several layers, i.e. at least two layers. These various layers may have
different
dissolving rates. This can provide the tablets with favorable performance
properties. If, for example, the tablets contain components which adversely
affect one another, one component may be integrated in the more quickly
dissolving layer while the other component may be incorporated in a more
slowly
dissolving layer so that the first component can already have reacted off by
the
time the second component dissolves. The various layers of the tablets can be
arranged in the form of a stack, in which case the inner layers) dissolve at
the
edges of the tablet before the outer layers have completely dissolved.
Alternatively, however, the inner layers) may also be completely surrounded by
the layers lying further to the outside which prevents constituents of the
inner
layers) from dissolving prematurely.
In another preferred embodiment of the invention, a tablet consists of at
least three layers, i.e. two outer layers and at least one inner layer, a
peroxy
bleaching agent being present in at least one of the inner layers whereas, in
the
case of the stack-like tablet, the two cover layers and, in the case of the
envelope-like tablet, the outermost layers are free from peroxy bleaching
agent.
In another possible embodiment, peroxy 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 example, with aqueous
solutions or emulsions or a coating may be obtained by the process known as
CA 02324070 2000-10-23
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:
5 2P
BDt
where ~ represents the diametral fracture stress (DFS) in Pa, P is the force
in N
10 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 compounds of
a) 60 to 95% by weight of anionic surfactant(s),
b) 5 to 40% by weight of hydrotrope(s) and
15 c) 0 to 35% by weight of carrier materials)
for improving the abrasion resistance of detergent tablets.
This use of the compounds mentioned in accordance with the invention
leads to tablets with advantageous properties, as the following Examples show.
The foregoing observations on the process according to the invention (particle
20 sizes, other ingredients, composition of the premix, etc.) apply equally to
preferred embodiments of the use according to the invention.
Examples
Surfactant-containing granules (for composition, see Table 1), which were
used as the basis for tablettable premixes, were produced by granulation in a
130
25 liter Lodige plowshare mixer. After granulation, the granules were dried
for 30
minutes in a Glatt fluidized bed dryer at an inflowing air temperature of
60°C.
After drying, fine particles (< 0.4 mm) and coarse particles (> 1.6 mm) were
removed by sieving.
The surfactant granules were then mixed with other components to form
30 compressible premixes which were then tabletted in a Korsch eccentric press
(tablet diameter 44 mm, weight 37.5 g). Premixes E1 and E2 according to the
invention contained 1 and 2% by weight of an ABS/toluene sulfonate compound
of which the composition is shown in Table 2. The particle size distributions
of
the compound are set out in Table 3.
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46
The tabletting pressure was adjusted so that four series of tablets (tablet
diameter 44 mm, weight 37.5 g) differing in their hardness were obtained. The
series with the lowest hardness were tested for abrasion because the problem
of
abrasion resistance is of course at its greatest in their case. The
composition of
the premixes to be tabletted (and hence the tablets) is shown in Table 4.
Table 1. Composition of the surfactant granules [% by weight]
C9_~3 alkyl benzenesulfonate 19.4
C~2_~g fatty alcohol sulfate 5.2
C~2_~8 fatty alcohol x 7 EO 4.8
C~2_~6 alkyl-1,4-glycoside 1.0
Soap 1.6
Sodium carbonate 17.0
Sodium silicate 5.6
Zeolite A 28.5
Optical brightener 0.3
Na hydroxyethane-1,1-diphosphonate0.8
Acrylic acid/maleic acid copolymer*5.6
Water, salts Balance
* Sokalan~ CP 5, BASF
Table 2. Composition of the ABS/toluenesulfonate compound [% by weight]
C9_~3 alkyl benzenesulfonate 79
Na toluene sulfonate 14
Sodium sulfate 6
Salts 1
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Table 3. Particle size distribution of the ABS/toluenesulfonate compound [% by
weight]
>1.6mm >1.2mm >0.8mm >0.4mm >0.2mm <0.2mm
1 2 38 53 5 1
Table 4. Composition of the premixes [% by weight]:
E1 E2 V
Surfactant granules (Table 1) 63 62 64
Sodium percarbonate 17 17 17
TAED 7.3 7.3 7.3
Foam inhibitor 3.5 3.5 3.5
Enzymes 1.7 1.7 1.7
Perfume 0.5 0.5 0.5
ABS/toluenesulfonate compound (Table1 2 -
2)
Wessalith~ XD (zeolite X) 2 2 2
Disintegration aid (cellulose) 5 5 5
The hardness of the tablets was measured after two days' storage 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
by the
tablet to disintegrate completely was measured.
Abrasion resistance was determined by placing a tablet on a 1.6 mm mesh
sieve. The sieve was then placed in a Retsch analytical sieving machine and
stressed at an amplitude of 2 mm for 120 seconds. The abrasion in % can be
calculated by weighing the tablet on the sieve before and after stressing. The
experimental data are shown in Table 5:
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Table 5. Detergent tablets [physical data]
Tablet E E2 V
Tablet hardness [N] 29 31 28
Tablet disintegration 7 8 7
[s]
Abrasion [%] 21 22 45
Tablet hardness [N] 41 39 42
Tablet disintegration 11 12 11
[s]
Tablet hardness [N] 52 50 48
Tablet disintegration 21 19 23
[s]
Tablet hardness [N] 59 63 61
Tablet disintegration 32 29 35
[s]
The disintegration time of the detergent tablets is slightly reduced and
abrasion clearly minimized by the use of the compounds according to the
invention.
