Note: Descriptions are shown in the official language in which they were submitted.
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Detergent Tablets Containing a Surfactantlbuilder Combination
This invention relates to tablets having detersive properties. More
particularly, the present invention relates to laundry detergent tablets for
washing laundry in domestic washing machines which are referred to in
short as detergent tablets.
Nowadays, detergents are commercially available in the form of
liquid or solid products. Solid products can be formulated as conventional
powders or as concentrates obtainable, for example, by granulation or
extrusion. Concentrated detergents have the advantage over conventional
powders that they are easier and less expensive to package and can be
used in smaller doses per wash cycle. The reduced pack sizes also reduce
transportation and storage costs. The most highly concentrated form in
which detergents are now commercially available in some countries are
tablets. Whereas water softeners and dishwashing detergents are widely
available in tablet form, tabletted laundry detergents pose various problems
which, hitherto, have prevented their use on a wide scale and have been
an obstacle to consumer acceptance. In view of the distinctly higher
surfactant contents, the problems normally occurring with tablets are
aggravated. Detergent tablets containing alkoxylated nonionic surfactants
are particularly problematical because surfactants belonging to this class
have an adverse effect on the solubility of the tablets. On the other hand,
the surfactants in question are particularly desirable by virtue of their high
cleaning performance.
The dichotomy between a sufficiently hard tablet and a sufficiently
short disintegration time is a central problem. Since sufficiently stable,
i.e.
dimensionally stable and fracture-resistant, tablets can only be produced by
relatively high tabletting pressures, the tablet ingredients are heavily
compacted which leads to delayed disintegration of the tablet in the
aqueous liquor and hence to slow release of the active substances during
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the washing or dishwashing process. Another disadvantage of the delayed
disintegration of the tablets is that conventional detergent tablets cannot be
introduced into the washing process from the dispensing compartment of
dishwashing machines because the tablets do not disintegrate sufficiently
quickly into secondary particles that are small enough to be flushed into the
washing drum from the dispensing compartment.
Numerous attempts to solve this problem have been made in the
prior art. In addition to the use of special ingredients intended to promote
disintegration, the coating of individual ingredients or the entire tablet has
also been proposed. These proposed solutions approach the problem so
to speak "from the formulation angle", i.e. certain ingredients are used or
the tablet or parts of the tablet is/are refined by additives. Besides these
"chemical" solutions, attempts have also been made to solve the above-
mentioned problem independently of the formulation. Most of these
"physical" solutions are concerned with certain embodiments of tabletting
machines or other process parameters, the tabletting pressure being of
primary concern. It has also been proposed to sieve the premixes to be
tabletted to certain particle fractions which is supposed to provide the
tablets with favorable properties irrespective of the composition of the
premix.
For example, European patent application EP 711 828 (Unilever)
claims a process for the production of detergent tablets by tabletting a
particulate composition containing a binder. The melting point of the binder
is said to be between 35 and 90°C, the tabletting process being carried
out
at temperatures below the melting point, but above 28°C. Accordingly,
this
document combines a "chemical" approach with a "physical" approach.
It would be of particular interest to be able largely to dispense with
the addition of substances which do not play an active part in the washing
or cleaning process in order largely to concentrate the active ingredients.
Accordingly, overcoming the above-described dichotomy through selective
' ~ CA 02300604 2000-03-10
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combinations of ingredients which, in addition, play an active role in the
washing or cleaning process is always particularly desirable.
It has now been found that phosphate-based detergent tablets
containing nonionic surfactants can be formulated with outstanding
performance properties providing they contain a zeolite of the faujasite type
(hereinafter referred to as faujasite zeolite) which is used in a certain
ratio
by weight to the nonionic surfactant.
The present invention relates to detergent tablets of compacted
particulate detergent containing surfactant(s), builders and optionally other
ingredients of detergents, characterized in that they contain nonionic
surfactants, phosphate builders and faujasite zeolite, the ratio of nonionic
surfactants to faujasite zeolite being between 1:20 and 1:1.
The tablets according to the invention contain nonionic surfactants,
phosphate builders and faujasite zeolite. Of these components, the
faujasite zeolite and the phosphate perform builder functions while nonionic
surfactants are present as detersive substances. Most of the builder is
normally made up by the phosphates.
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 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 dihydrate
(density 1.91 gcm~3, melting point 60°) and as the monohydrate (density
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2.04 gcm~3). Both salts are white readily water-soluble powders which, on
heating, lose the water of crystallization and, at 200°, 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
HZO),
becomes water-free at 100° and, on fairly intensive heating, is
converted
into the diphosphate Na4P20~. Disodium hydrogen phosphate is prepared
by neutralization of phosphoric acid with soda solution using phenol-
phthalein 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 solution of exactly 1 mole of disodium
phosphate and 1 mole of NaOH by evaporation. Tripotassium phosphate
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(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.
5 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), Na4P20~, 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.
Na4P20~ 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
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which crystallizes without water or with 6 H20 and which has the general
formula Na0-[P(O)(ONa)-O]~-Na where n = 3. Around 17 g of the salt free
from water of crystallization dissolve in 100 g of water at room temperature,
around 20 g at 60° and around 32 g at 100°. After heating of the
solution
for 2 hours to 100°, around 8% orthophosphate and 15% diphosphate are
formed by hydrolysis. In the preparation of pentasodium triphosphate,
phosphoric acid is reacted with soda solution or sodium hydroxide in a
stoichiometric ratio and the solution is spray-dried. Similarly to Graham's
salt and sodium diphosphate, pentasodium triphosphate dissolves many
insoluble metal compounds (including lime soaps, etc.). Pentapotassium
triphosphate, 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.
According to the invention, preferred detergent tablets contain alkali
metal phosphates, preferably pentasodium or pentapotassium triphosphate
(sodium or potassium tripolyphosphate) as phosphates in quantities of 1 to
60% by weight, preferably in quantities of 5 to 50% by weight, more
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preferably in quantities of 10 to 40% by weight and most preferably in
quantities of 15 to 35% by weight, based on tablet weight.
The zeolite also present in the tablets in accordance with the
invention has the general formula M2,~0 ~ AI203 ~ x Si02 ~ y H20, where M is
a cation with the valence n, x has a value of or greater than 2 and y may
assume a value of 0 to 20. The zeolite structures are formed by the
connection of A104 tetrahedra to Si04 tetrahedra, this framework being
occupied by cations and water molecules. The cations in these structures
are relatively mobile and may be replaced to various extents by other
cations. The intercrystalline (zeolitic) water can be given off continuously
and reversibly, according to the type of zeolite, whereas with some zeolite
types structural changes also accompany the release or uptake of water.
In the structural subunits, the "primary structural units" (A104
tetrahedra and Si04 tetrahedra) form so-called "secondary building units"
which assume the form of single or multiple rings. For example, 4-, 6- and
8-membered rings (termed S4R, S6R and S8R) occur in various zeolites
while other types are connected by 4- and 6-membered double ring prisms
(most common types: D4R as a rectangular prism and D6R as a hexagonal
prism). The "secondary subunits" connect various polyhedra which are
denoted by Greek letters. The most common is a polyhedron which is
made up of six squares and eight equal-sided hexagons and which is
called "~i". Various different zeolites can be produced up from these
building units. At the present time, 34 natural zeolite minerals and
approximately 100 synthetic zeolites are known.
The well-known zeolite, zeolite 4 A, is a cubic assemblage of ~i-
cages connected by D4R subunits. It belongs to zeolite structure group 3
and its three-dimensional framework has pores 2.2 A and 4.2 A in size.
The formula unit in the elementary cell may be described thus:
Na~2I(AIOZ)~2(Si02)~21 ~ 27 H20.
According to the invention, faujasite zeolites are used in the
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detergent tablets according to the invention. Together with zeolites X and
Y, the mineral faujasite belongs to the faujasite types within zeolite
structure group 4 which is characterized by the double 6-membered ring
subunit D6R (cf. Donald W. Breck: "Zeolite Molecular Sieves", John
Wiley ~ Sons, New York, London, Sydney, Toronto, 1974, page 92).
Besides the faujasite types mentioned, the minerals chabasite and
gmelinite and the synthetic zeolites R (chabasite type), S (gmelinite type), L
and ZK-5 belong to zeolite structure group 4. The last two of these
synthetic zeolites do not have any mineral analogs.
Faujasite zeolites are made up of ~i-cages tetrahedrally linked by
D6R subunits, the ~-cages being arranged similarly to the carbon atoms in
diamond. The three-dimensional framework of the faujasite zeolites used
in the process according to the invention has pores 2.2 and 7.4 A in size.
In addition, the elementary cell contains eight cavities each ca. 13 A in
diameter and may be described by the formula Na86[(A102)86(Si02)~os] ~ 264
HZO. The framework of the zeolite X contains a void volume of around
50%, based on the dehydrated crystal, which represents the largest empty
space of all known zeolites (zeolite Y: ca. 48% void volume, faujasite: ca.
47% void volume). (All data from: Donald W. Breck: "Zeolite Molecular
Sieves", John Wiley & Sons, New York, London, Sydney, Toronto, 1974,
pages 145, 176, 177).
In the context of the present invention, the expression "faujasite
zeolite" characterizes all three zeolites which form the faujasite subgroup of
zeolite structure group 4. According to the invention, therefore, zeolite Y
and faujasite and mixtures of these compounds may also be used in
addition to zeolite X although pure zeolite X is preferred. Mixtures of co-
crystallizates of faujasite zeolites with other zeolites, which do not
necessarily have to belong to zeolite structure group 4, may also be used in
accordance with the invention.
The aluminium silicates used in the process according to the
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invention are commercially obtainable and the methods for their production
are described in standard works.
Examples of commercially available X-type zeolites may be
described by the following formulae:
Naas[(AIO2)as(Si02)~osl ~ x H20,
Kas[(A102)as(Si02)~os] ~ x H20,
Ca4oNas[(A102)as(Si02)~os] ~ x H20,
Sr2~Ba22[(AIO2)as(Si02)~os] ~ x H20,
in which x may assume a value of 0 to 276 and which have pore sizes of
8.0 to 8.4.
For example, a co-crystallizate of zeolite X and zeolite A (ca. 80% by
weight zeolite X), which is marketed by CONDEA Augusta S.p.A. under the
name of VEGOBOND AX~ and which may be described by the following
formula:
nNa20 ~ (1-n)K20 ' A12O3 ~ (2 - 2.5)Si02 (3.5 - 5.5) H20
is commercially obtainable and may be used with advantage in the process
according to the invention.
Zeolites of the Y type are also commercially obtainable and may be
described, for example, by the following formulae:
NaSS[(AIOp)56(SIOp)136] ~ x H20,
0 K56[(AIOp)56(SIO2)136] ~ x H20,
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in which x is a number of 0 to 276 and which have pore sizes of 8.0 A.
According to the invention, preferred detergent tablets are charac-
terized in that the ratio of nonionic surfactants to the faujasite zeolite is
5 between 1:15 and 1:1.25, preferably between 1:10 and 1:1.5 and more
preferably between 1:5 and 1:2. The faujasite zeolite is preferably used in
quantities of 0.5 to 20% by weight, more preferably in quantities of 1 to
15% by weight, most preferably in quantities of 2 to 10% by weight and, in
one particularly preferred embodiment, in quantities of 2.5 to 5% by weight,
10 based on tablet weight, zeolite X being preferred.
The tablets according to the invention contain nonionic surfactants
as a third compulsory component. These are described in the following:
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 resi
dues 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_~8 alcohols containing 3 EO, 5 EO or 7 EO and mixtures thereof, such
as mixtures of C~2_~4 alcohol containing 3 EO and C~2_~$ alcohol containing
5 EO. The degrees of ethoxylation mentioned represent statistical mean
values which, for a special product, can be a whole number or a broken
number. Preferred alcohol ethoxylates have a narrow homolog distribution
(narrow range ethoxylates, NRE). In addition to these nonionic surfactants,
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fatty alcohols containing more than 12 EO may also be used, examples
including tallow alcohol containing 14 EO, 25 EO, 30 EO or 40 EO.
Another class of preferred nonionic surfactants which may be used
either as sole nonionic surfactant or in combination with other nonionic
surfactants are alkoxylated, preferably ethoxylated or ethoxylated and
propoxylated, fatty acid alkyl esters preferably containing 1 to 4 carbon
atoms in the alkyl chain, more especially the fatty acid methyl esters which
are described, for example, in Japanese patent application JP 581217598
or which are preferably produced by the process described in International
patent application WO-A-90113533.
Another class of nonionic surfactants which may advantageously be
used are the alkyl polyglycosides (APGs). Suitable alkyl polyglycosides
correspond to the general formula RO(G)Z where R is a linear or branched,
more particularly 2-methyl-branched, saturated or unsaturated aliphatic
radical containing 8 to 22 and preferably 12 to 18 carbon atoms and G
stands for a glycose unit containing 5 or 6 carbon atoms, preferably
glucose. The degree of glycosidation z is between 1.0 and 4.0, preferably
between 1.0 and 2.0 and more preferably between 1.1 and 1.4.
Linear alkyl polyglucosides, i.e. alkyl polyglycosides in which the
polyglycosyl component is a glucose unit and the alkyl component is an n
alkyl group, are preferably used.
The surfactant granules according to the invention may
advantageously contain alkyl polyglycosides, APG contents of more than
0.2% by weight, based on the tablet as a whole, being preferred.
Particularly preferred detergent tablets contain APGs in quantities of 0.2 to
10% by weight, preferably in quantities of 0.2 to 5% by weight and more
preferably in quantities of 0.5 to 3% by weight.
Nonionic surfactants of the amine oxide type, for example N
coconutalkyl-N,N-dimethylamine oxide and N-tallowalkyl-N,N-dihydroxy
ethylamine oxide, and the fatty acid alkanolamide type are also suitable.
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The quantity in which these nonionic surfactants are used is preferably no
more than the quantity in which the ethoxylated fatty alcohols are used
and, more preferably, no more than half that quantity.
Other suitable surfactants are polyhydroxyfatty acid amides
corresponding to formula (I):
R'
R-CO-N-[Z] (I)
in which RCO is an aliphatic acyl group containing 6 to 22 carbon atoms,
R' is hydrogen, an alkyl or hydroxyalkyl group containing 1 to 4 carbon
atoms and [Z] is a linear or branched polyhydroxyalkyl group containing 3
to 10 carbon atoms and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid
amides are known substances which may normally be obtained by
reductive amination of a reducing sugar with ammonia, an alkylamine or an
alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl
ester or a fatty acid chloride.
The group of polyhydroxyfatty acid amides also includes compounds
corresponding to formula (II):
R' -O-R2
R-C O-N-[Z] ( I I )
in which R is a linear or branched alkyl or alkenyl group containing 7 to 12
carbon atoms, R' is a linear, branched or cyclic alkyl group or an aryl group
containing 2 to 8 carbon atoms and R2 is a linear, branched or cyclic alkyl
group or an aryl group or an oxyalkyl group containing 1 to 8 carbon atoms,
C,~ alkyl or phenyl groups being preferred, and [Z] is a linear polyhydroxy-
alkyl group, of which the alkyl chain is substituted by at least two hydroxyl
groups, or alkoxylated, preferably ethoxylated or propoxylated, derivatives
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of that group.
[Z] is preferably obtained by reductive amination of a reduced sugar,
for example glucose, fructose, maltose, lactose, galactose, mannose or
xylose. The N-alkoxy- or N-aryloxy-substituted compounds may then be
converted into the required polyhydroxyfatty acid amides by reaction with
fatty acid methyl esters in the presence of an alkoxide as catalyst, for
example in accordance with the teaching of International patent application
WO-A-95107331.
According to the invention, preferred detergent tablets contain
nonionic surfactants in quantities of 0.5 to 20% by weight, preferably in
quantities of 1 to 10% by weight and more preferably in quantities of 1.5 to
5% by weight, based on tablet weight.
Nonionic surfactants from any of the groups mentioned above may
be used for the purposes of the invention. Irrespective of the chemical
nature of the nonionic surfactants used, the nonionic surfactants present in
the detergent tablets preferably have a melting point below 40°C,
According to the invention, particularly preferred nonionic surfactants
are alcohol alkoxylates. In the context of the present invention, the
expression "alkylene oxide units" characterizes the statistical average
number of AO groups in one molecule of the nonionic surfactant or, in other
words, the statistical average number of moles of alkylene oxide present
per mole of alcohol. Ethylene oxide (EO) and propylene oxide (PO) units in
particular are of interest as alkylene oxide units. The corresponding
alkoxylates may be obtained in known manner from the alcohols and
ethylene or propylene oxide. EO/PO mixtures may of course also be used
for the purposes of the present invention.
The structure of the highly alkoxylated nonionic surfactants is
variable within wide limits. The alkyl group is determined by the choice of
the long-chain alcohol. The industrially obtainable alcohols containing 8 to
24 carbon atoms, more particularly native alcohols from the hydrogenation
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of carboxylic acids or carboxylic acid derivatives, are preferred on
economic grounds. The alcohols obtainable from industrial-scale alcohol
syntheses, such as oxo alcohols and Ziegler alcohols, may also be used.
The alcohols obtainable from the hydrogenation of carboxylic acids
are termed fatty alcohols because the acids are obtained from native fats
and oils. They are not pure substances but rather mixtures of variable
composition. According to the invention, fatty alcohols suitable for use as
the alkyl moiety of the alkoxylated nonionic surfactants are, for example,
hexanol (caproic alcohol), heptanol (oenanthic alcohol), octanol (caprylic
alcohol), nonanol (pelargonic alcohol), decanol (capric alcohol), undecanol,
etc. According to the invention, it is preferred to use fatty alcohols, such
as
dodecanol (lauryl alcohol), tetradecanol (myristyl alcohol), hexadecanol
(palmityl alcohol), octadecanol (stearyl alcohol), eicosanol (arachyl
alcohol), docosanol (behenyl alcohol), tetracosanol (lignoceryl alcohol),
hexacosanol (cerotyl alcohol), triacontanol (melissy alcohol) and the
unsaturated species 9c-hexadecenol (palmitoleyl alcohol), 6c-octadecenol
(petroselinyl alcohol), 6t-octadecenol (petroselaidyl alcohol), 9c-
octadecenol (oleyl alcohol), 9t-octadecenol (elaidyl alcohol), 9c,12c-
octadecadienol (linoleyl alcohol), 9t,12t-octadecadienol (linolaidyl alcohol)
and 9c,12c,15c-octadecatrienol (linolenyl alcohol). For reasons of cost,
technical mixtures of the individual acids obtainable by the hydrolysis of
fats and subsequent hydrogenation are used in preference to the pure
species. Mixtures such as these are, for example, cocofatty alcohol (ca.
6% by weight C8, 6% by weight Coo, 48% by weight C~2, 18% by weight
C~4, 10% by weight C~6, 2% by weight C~8, 8% by weight C~8~, 1 % by weight
C~8~~), palm kernel oil fatty alcohol (ca. 4% by weight C8, 5% by weight Coo,
50% by weight C~2, 15% by weight C~4, 7% by weight C~6, 2% by weight
C~8, 15% by weight C~a~, 1% by weight C~8~~), tallow alcohol (ca. 3% by
weight C~4, 26% by weight C~6, 2% by weight C~6~, 2% by weight C~~, 17%
by weight CAB, 44% by weight C~8~, 3% by weight C~8~~, 1 % by weight C~B~~~),
CA 02300604 2000-03-10
hydrogenated tallow alcohol (ca. 2% by weight C~4, 28% by weight C~s, 2%
by weight C», 63% by weight C~8, 1% by weight C~8~), hydrogenated
technical oleic acid (ca. 1 % by weight C~2, 3% by weight C~4, 5% by weight
C~6, 6% by weight C~s~, 1 % by weight C~~, 2% by weight C~8, 70% by weight
5 C~8~, 10% by weight C~a~~, 0.5% by weight C~8~~~), technical
palmityl/stearyl
acid (ca. 1% by weight C~2, 2% by weight C~4, 45% by weight C~6, 2% by
weight C», 47% by weight C~8, 1 % by weight C~B~) and hydrogenated
soybean oil fatty acid (ca. 2% by weight C~4, 15% by weight C~6, 5% by
weight CAB, 25% by weight C~8~, 45% by weight C~a~~, 7% by weight C~8~~~).
10 According to the invention, particularly preferred alkoxylated
nonionic surfactants are fatty alcohol ethoxylates. Preferred detergent
tablets contain alcohol ethoxylates corresponding to the following general
formula:
Cnl"'12n+~ O-(CH2CH20)mH
in which n assumes a value of 8 to 24, preferably 10 to 22, more preferably
12 to 20 and most preferably 12 to 18 and m assumes a value of 1 to 20,
preferably 2 to 15, more preferably 4 to 10 and most preferably 6 to 8,
as nonionic surfactants.
Besides nonionic surfactants, the detergent tablets according to the
invention may also contain other detersive substances, more partiularly
from the groups of anionic, cationic and zwitterionic surfactants, anionic
surfactants being distinctly preferred on economic grounds and for their
performance spectrum.
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_~8 monoolefins with an internal or terminal double bond by sulfonation
with gaseous sulfur trioxide and subsequent alkaline or acidic hydrolysis of
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16
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 neutral-
ization. The esters of a-sulfofatty acids (ester sulfonates), for example the
a-sulfonated methyl esters of hydrogenated coconut, palm kernel or tallow
acids, are also suitable.
Other suitable anionic surfactants are sulfonated fatty acid glycerol
esters. 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 coconut alcohol, tallow alcohol, lauryl, myristyl, cetyl
or stearyl alcohol, or C~o_2o oxoalcohols and the corresponding semiesters
of secondary alcohols with the same chain length. Other preferred
alk(en)yl sulfates are those with the chain length mentioned which contain
a synthetic, linear alkyl chain based on a petrochemical and which are
similar in their degradation behavior to the corresponding compounds
based on oleochemical raw materials. C~2_~6 alkyl sulfates, C~2_~5 alkyl
sulfates and C~4_~5 alkyl sulfates are preferred from the point of view of
washing technology. Other suitable anionic surfactants are 2,3-alkyl
sulfates which may be produced, for example, in accordance with US
3,234,258 or US 5,075,041 and which are 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
CA 02300604 2000-03-10
17
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_~g 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 Ca_~8 fatty
alcohol residues or mixtures thereof. Particularly preferred sulfosuccinates
contain a fatty alcohol residue derived from ethoxylated fatty alcohols
which, considered in isolation, represent nonionic surfactants (for a
description, see below). Of these sulfosuccinates, those of which the fatty
alcohol residues are derived from narrow-range ethoxylated fatty alcohols
are particularly preferred. Alk(en)yl succinic acid preferably containing 8 to
18 carbon atoms in the alk(en)yl chain or salts thereof may also be used.
Other suitable anionic surfactants are, in particular, soaps. Suitable
soaps are saturated fatty acid soaps, such as the salts of lauric acid,
myristic acid, palmitic acid, stearic acid, hydrogenated erucic acid and
behenic acid, and soap mixtures derived in particular from natural fatty
acids, for example coconut, palm kernel or tallow fatty acids.
The anionic surfactants, including the soaps, may be present in the
form of their sodium, potassium or ammonium salts and as soluble salts of
organic bases, such as mono-, di- or triethanolamine. The anionic
surfactants are preferably present in the form of their sodium or potassium
salts and, more preferably, in the form of their sodium salts.
According to the invention, preferred detergent tablets are those
which contain 5 to 50% by weight, preferably 7.5 to 40% by weight and
more preferably 10 to 20% by weight of anionic surfactants, based on the
CA 02300604 2000-03-10
18
weight of the tablet.
So far as the choice of anionic surfactants used in the detergent
tablets according to the invention is concerned, there are no basic
requirements to restrict the freedom of formulation. However, preferred
surfactant tablets do have a soap content in excess of 0.2% by weight,
based on the total weight of the detergent tablet. Preferred anionic
surfactants are alkyl benzenesulfonates and fatty alcohol sulfates,
preferred detergent tablets additionally containing anionic surfactant(s),
preferably fatty alcohol sulfate(s), in quantities of 2 to 20% by weight,
preferably 2.5 to 15% by weight and more preferably 5 to 10%, based on
tablet weight.
Phosphate(s), faujasite zeolite(s) and nonionic surfactants) may be
introduced into the detergent tablets according to the invention in any way.
It has proved to be of advantage for the premix to be tabletted to contain
phosphates) and faujasite zeolite(s) in the form of surfactant granules. To
this end, surfactant granules preferably containing the entire quantity of
phosphates and faujasite zeolites present in the tablets are initially
prepared and subsequently mixed with other aftertreatment components,
after which the premix is tabletted. In addition, the surfactant granules
mentioned above preferably contain the entire quantity of nonionic
surfactants present in the tablets and preferably even the entire quantity of
all the surfactants present in the tablets. In summary, therefore, preferred
detergent tablets are characterized in that they contain the total quantity of
phosphates and faujasite zeolites in the form of surfactant granules which
preferably also contain the total quantity of surfactants present in the
tablets.
These preferred surfactant granules according to the invention
naturally have higher phosphate contents than the tablet as a whole.
According to the invention, preferred detergent tablets are characterized in
that the surfactant granules contain 5 to 70% by weight, preferably 10 to
CA 02300604 2000-03-10
19
65% by weight, more preferably 20 to 60% by weight and most preferably
25 to 50% by weight of phosphate, based on the weight of the surfactant
granules.
Other detergent ingredients, more particularly so-called minor
components, such as optical brighteners, polymers, defoamers,
phosphonates, dyes and perfumes, may also be part of the surfactant
granules. These substances are described hereinafter. The premix to be
tabletted may additionally one or more substances from the groups of
bleaching agents, bleach activators, disintegration aids, etc. In one
particular embodiment of the present invention, the substances mentioned,
which are described hereinafter, may also be part of the surfactant
granules.
The present invention also relates to a process for the production of
detergent tablets by mixing surfactant-containing granules with powder-
form aftertreatment components and tabletting the resulting premix, charac-
terized in that the premix to be tabletted contains nonionic surfactants,
phosphate builders and faujasite zeolite, the ratio of nonionic surfactants to
faujasite zeolite being between 1:20 and 1:1.
The foregoing observations on the detergent tablets according to the
invention apply equally to the process according to the invention in regard
to preferred embodiments and quantities of individual components.
Accordingly, preferred processes are characterized for example in that the
surfactant-containing granules contain the entire quantity of phosphates
and faujasite zeolites present in the tablets, granules additionally
containing the total quantity of nonionic surfactants and preferably the total
quantity of all surfactants being preferred.
In preferred variants of the process according to the invention, the
premix to be tabletted contains surfactant-containing granules) and other
aftertreatment components, phosphate(s), faujasite zeolite(s) and the
surfactants being part of the granules. The surfactant-containing granules
CA 02300604 2000-03-10
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 for the premix to be tabletted to have a bulk density similar
5 to that of conventional compact detergents. In one particularly preferred
embodiment, the premix to be tabletted has a bulk density of at least 500
g/I, preferably of at least 600 g/I and more preferably of at least 700 g/I.
In preferred process variants, the surfactant-containing granules
satisfy certain particle size criteria. Thus, preferred processes according to
10 the invention are characterized in that the surfactant-containing granules
have particle sizes of 100 to 2000 Nm, preferably in the range from 200 to
1800 Nm, more preferably in the range from 400 to 1600 Nm and most
preferably in the range from 600 to 1400 Nm.
Besides the active substances (anionic and/or nonionic and/or
15 cationic and/or amphoteric surfactants), the surfactant granules preferably
also contain carrier materials which, in one particularly preferred
embodiment, belong to the group of builders. Particularly advantageous
processes are characterized in that the premix to be tabletted contains
surfactant-containing granules which contain anionic and/or nonionic
20 surfactants and builders and of which the total surfactant content is
between 5 and 60% by weight, preferably between 10 and 50% by weight
and more preferably between 15 and 40% by weight, based on the
surfactant granules.
In order to incorporate the required quantity of detersive substance
in the detergent tablets, process variants in which the premix contains
surfactant-containing granules with surfactant contents of 5 to 60% by
weight, preferably 10 to 50% by weight and more preferably 15 to 40% by
weight, based on the weight of the surfactant granules, (see above) are
preferred. According to the invention, detergent tablets where the
surfactant granules contain 5 to 45% by weight, preferably 10 to 40% by
CA 02300604 2000-03-10
21
weight and more preferably 15 to 35% by weight, based on the weight of
the surfactant granules, of anionic surfactants and detergent tablets where
the surfactant granules contain 1 to 30% by weight, preferably 5 to 25% by
weight and more preferably 7.5 to 20% by weight, based on the weight of
the surfactant granules, of nonionic surfactants are particularly preferred.
Particularly preferred variants of the process according to the invention are
characterized in that the surfactant-containing granules make up from 40 to
95% by weight, preferably from 45 to 85% by weight and more preferably
from 55 to 75% by weight, based on the weight of the detergent tablets, of
the premix to be tabletted and hence of the detergent tablets.
As part of the surfactant granules, but also as an aftertreatment
component optionally added to the premix, builders are important
ingredients of detergents. Besides the detersive ingredients, builders are
the most important ingredients of detergents. 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 and organic
co-builder. According to the invention, however, phosphates are
prefrerably used as the principal builder (see above).
The finely crystalline, synthetic zeolite containing bound water used
in accordance with the invention is preferably zeolite A and/or zeolite P.
Zeolite MAP (Crosfield) is a particularly preferred P-type zeolite.
However, zeolite X and mixtures of A, X and/or P are also suitable. 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.
Crystalline layer-form sodium silicates suitable as builders corre-
spond to the general formula NaMSiXO~+~A y H20, where M is sodium or
hydrogen, x is a number of 1.9 to 4 and y is a number of 0 to 20, preferred
values for x being 2, 3 or 4. Crystalline layer silicates such as these are
described, for example, in European patent application EP-A-0 164 514.
CA 02300604 2000-03-10
22
Preferred crystalline layer silicates corresponding to the above formula are
those in which M is sodium and x assumes the value 2 or 3. Both (i- and 8-
sodium disilicates Na2Si205A y HZO are particularly preferred, ~i-sodium
disilicate being obtainable, for example, by the process described in
International patent application WO-A-91108171.
Other useful builders are amorphous sodium silicates with a
modulus (Na20:Si02 ratio) of 1:2 to 1:3.3, preferably 1:2 to 1:2.8 and more
preferably 1:2 to 1:2.6 which dissolve with delay and exhibit multiple wash
cycle properties. The delay in dissolution in relation to conventional
amorphous sodium silicates can have been obtained in various ways, for
example by surface treatment, compounding, compacting or by overdrying.
In the context of the invention, the term amorphous is also understood to
encompass X-ray amorphous . In other words, the silicates do not
produce any of the sharp X-ray reflexes typical of crystalline substances in
X-ray diffraction experiments, but at best one or more maxima of the
scattered X-radiation which have a width of several degrees of the
diffraction angle. However, particularly good builder properties may even
be achieved where the silicate particles produce crooked or even sharp
diffraction maxima in electron diffraction experiments. This may be
interpreted to mean that the products have microcrystalline regions
between 10 and a few hundred nm in size, values of up to at most 50 nm
and, more particularly, up to at most 20 nm being preferred. So-called X-
ray amorphous silicates such as these, which also dissolve with delay in
relation to conventional waterglasses, are described for example in
German patent application DE-A-44 00 024. Compacted amorphous
silicates, compounded amorphous silicates and overdried X-ray-amorphous
silicates are particularly preferred.
Organic cobuilders which may be used in the detergent tablets
according to the invention include, in particular, polycarboxy
lates/polycarboxylic acids, polymeric polycarboxylates, aspartic acid,
CA 02300604 2000-03-10
23
polyacetals, dextrins, other organic cobuilders (see below) and phos-
phonates. Substances belonging to these classes 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 carrying more than
one acid function). Examples include citric acid, adipic acid, succinic acid,
glutaric acid, malic acid, tartaric acid, malefic acid, fumaric acid, sugar
acids, aminocarboxylic acids, nitrilotriacetic acid (NTA), providing its use
is
not ecologically unsafe, and mixtures thereof. Preferred salts are the salts
of the polycarboxylic acids, such as citric acid, adipic acid, succinic acid,
glutaric acid, tartaric acid, sugar acids and mixtures thereof.
The acids per se may also be used. Besides their builder effect, the
acids typically have the property of an acidifying component and,
accordingly, are also used to establish a lower and more mild pH value in
laundry or dishwashing detergents. Citric acid, succinic acid, glutaric acid,
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 acid or polymethacrylic acid,
for example those having a relative molecular weight of 500 to 70,000
g/mole.
The molecular weights mentioned in this specification for polymeric
polycarboxylates are weight-average molecular weights Mw of the particular
acid form which, basically, were determined by gel permeation
chromatography (GPC) using a UV detector. The measurement was
carried out against an external polyacrylic acid standard which provides
realistic molecular weight values by virtue of its structural similarity to
the
polymers investigated. These values differ distinctly from the molecular
weights measured against polystyrene sulfonic acids as standard. The
CA 02300604 2000-03-10
24
molecular weights measured against polystyrene sulfonic acids are
generally far higher than the molecular weights mentioned in this
specification.
Suitable polymers are, in particular, polyacrylates which preferably
have a molecular weight of 2,000 to 20,000 g/mole. By virtue of their
superior solubility, preferred representatives of this group are the short-
chain polyacrylates which have molecular weights of 2,000 to 10,000
g/mole and, more particularly, 3,000 to 5,000 g/mole.
Also suitable are copolymeric polycarboxylates, particularly those of
acrylic acid with methacrylic acid and those of acrylic acid or methacrylic
acid with malefic acid. Acrylic acid/maleic acid copolymers containing 50 to
90% by weight of acrylic acid and 50 to 10% by weight of malefic acid have
proved to be particularly suitable. Their relative molecular weight, based
on the free acids, is generally in the range from 2,000 to 70,000 g/mole,
preferably in the range from 20,000 to 50,000 g/mole and more preferably
in the range from 30,000 to 40,000 g/mole.
The (co)polymeric polycarboxylates may be used either in powder
form or in the form of an aqueous solution. The content of (co)polymeric
polycarboxylates in the compositions is preferably between 0.5 and 20% by
weight and more preferably between 3 and 10% by weight.
In order to improve their solubility in water, the polymers may also
contain allyl sulfonic acids, for example allyloxybenzenesulfonic acid and
methallyl sulfonic acid as monomer.
Biodegradable polymers of more than two different monomer units
are also particularly preferred, examples including those which contain
salts of acrylic acid and malefic acid and vinyl alcohol or vinyl alcohol
derivatives as monomers or those which contain salts of acrylic acid and 2-
alkylallyl sulfonic acid and sugar derivatives as monomers.
Other preferred copolymers are those described in German patent
applications DE-A-43 03 320 and DE-A-44 17 734 which preferably contain
CA 02300604 2000-03-10
acrolein and acrylic acid/acrylic acid salts or acrolein and vinyl acetate as
monomers.
Other preferred builders are polymeric aminodicarboxilic acids, salts
or precursors thereof. Polyaspartic acids or salts and derivatives thereof
5 which, according to German patent application DE-A-195 40 086, have a
bleach-stabilizing effect in addition to their co-builder properties are
particularly preferred.
Other suitable builders are polyacetals which may be obtained by
reaction of dialdehydes with polyol carboxylic acids containing 5 to 7
10 carbon atoms and at least three hydroxyl groups. Preferred polyacetals are
obtained from dialdehydes, such as glyoxal, glutaraldehyde, terephthal-
aldehyde and mixtures thereof and from polyol carboxylic acids, such as
gluconic acid and/or glucoheptonic acid.
Other suitable organic builders are dextrins, for example oligomers
15 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
20 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 syrups with a DE of 20 to 37 and also so-called yellow
dextrins and white dextrins with relatively high molecular weights of 2,000
25 to 30,000 g/mole may be used.
The oxidized derivatives of such dextrins are their reaction products
with oxidizing agents which are capable of oxidizing at least one alcohol
function of the saccharide ring to the carboxylic acid function. Dextrins thus
oxidized and processes for their production are known, for example, from
European patent applications EP-A-0 232 202, EP-A-0 427 349, EP-A-0
CA 02300604 2000-03-10
26
472 042 and EP-A-0 542 496 and from International patent applications
WO 92118542, WO 93/08251, WO 93/16110, WO 94128030, WO 95107303,
WO 95112619 and WO 95120608. An oxidized oligosaccharide according
to German patent application DE-A-196 00 018 is also suitable. A product
oxidized at Cs of the saccharide ring can be particularly advantageous.
Other suitable co-builders are oxydisuccinates and other derivatives
of disuccinates, preferably ethylenediamine disuccinate. Ethylenediamine-
N,N'-disuccinate (EDDS) is preferably used in the form of its sodium or
magnesium salts. Glycerol disuccinates and glycerol trisuccinates are also
particularly preferred in this connection. The quantities used in zeolite-
containing and/or silicate-containing formulations are from 3 to 15% by
weight.
Other useful organic co-builders are, for example, acetylated
hydroxycarboxylic acids and salts thereof which may optionally be present
in lactone form and which contain at least 4 carbon atoms, at least one
hydroxy group and at most two acid groups. Co-builders such as these are
described, for example, in International patent application WO-A-95120029.
Another class of substances with co-builder properties are the
phosphonates, more particularly hydroxyalkane and aminoalkane phos
phonates. Among the hydroxyalkane phosphonates, 1-hydroxyethane-1,1
diphosphonate (HEDP) is particularly important as a co-builder. It is
preferably used in the form of a sodium salt, the disodium salt showing a
neutral reaction and the tetrasodium salt an alkaline ration (pH 9).
Preferred aminoalkane phosphonates are ethylenediamine tetramethylene
phosphonate (EDTMP), diethylenetriamine pentamethylene phosphonate
(DTPMP) and higher homologs thereof. They are preferably used in the
form of the neutrally reacting sodium salts, for example as the hexasodium
salt of EDTMP and as the hepta- and octasodium salt of DTPMP. Within
the class of phosphonates, HEDP is preferably used as builder. The
aminoalkane phosphonates also show a pronounced heavy metal binding
CA 02300604 2000-03-10
27
capacity. Accordingly, it can be of advantage, particularly where the
detergents also contain bleaching agents, to use aminoalkane
phosphonates, more especially DTPMP, or mixtures of the phosphonates
mentioned.
In addition, any compounds capable of forming complexes with
alkaline earth metal ions may be used as co-builders.
The production of surfactant-containing granules is widely described
in the prior art literature, including many patents and numerous synoptic
articles and books. Thus, W. Hermann de Groot, I. Adami and G.F. Moretti
describe various spray drying, mixing and granulation processes for the
production of detergents in "The Manufacture of Modern Detergent
Powders", Hermann de Groot Academic Publisher, Wassenaar, 1995.
On energy grounds, the surfactant-containing granules are
preferably produced by a granulation process and not by spray drying
according to the invention. Besides conventional granulation and
agglomeration processes, which may be carried out in various mixer-
granulators and mixer-agglomerators, press agglomeration processes, for
example, may also be used. Accordingly, processes in which the
surfactant-containing granules are produced by granulation, agglomeration,
press agglomeration or a combination of these processes are preferred.
The granulation process may be carried out in a number of
machines typically used in the detergent industry. For example, the
spheronizers widely used in the pharmaceutical industry may be employed.
In rotary machines such as these, the residence time of the granules is
normally less than 20 seconds. Conventional mixers and mixer-granulators
are also suitable for granulation. The mixers used may be both high-shear
mixers and also normal mixers with lower rotational speeds. Suitable
mixers are, for example, Series R or RV Eirich~ mixers (trademarks of
Maschinenfabrik Gustav Eirich, Hardheim), the Schugi~ Flexomix mixer,
the Fukae~ FS-G mixers (trademarks of Fukae Powtech, Kogyo Co.,
CA 02300604 2000-03-10
28
Japan), Lodige~ FM, KM and CB mixers (trademarks of Lodige
Maschinenbau GmbH, Paderborn) and Series T or K-T Drais~ mixers
(trademarks of Drais-Werke GmbH, Mannheim). The residence times of
the granules in the mixers is less than 60 seconds, the residence time also
depending on the rotational speed of the mixer. The residence times are
shorter, the higher the rotational speed of the mixer. The residence times
of the granules in the mixer/spheronizer are preferably under one minute
and more preferably under 15 seconds. In low-speed mixers, for example
a Lodige KM, residence times of up to 20 minutes are adjusted, residence
times of under 10 minutes being preferred in the interests of process
economy.
In the press agglomeration process, the surfactant-containing
granules are shear-compacted under pressure and, at the same time,
homogenized and are then discharged from the machine via a
shaping/forming stage. Industrially the most important press agglomeration
processes are extrusion, roll compacting, pelleting and tabletting. Press
agglomeration processes preferably used in accordance with the invention
for producing the surfactant-containing granules are extrusion, roll
compacting and pelleting.
In order to facilitate the disintegration of heavily compacted tablets,
disintegration aids, so-called tablet disintegrators, may be incorporated in
them to shorten their disintegration times. According to Rompp (9th
Edition, Vol. 6, page 4440) and Voigt "Lehrbuch der pharmazeutischen
Technologie" (6th Edition, 1987, pages 182-184), tablet disintegrators or
disintegration accelerators are auxiliaries which provide for 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
CA 02300604 2000-03-10
29
(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 dis-
integration 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)n and, formally, is
a ~3-1,4-polyacetal of cellobiose which, in turn, is made up of two molecules
of glucose. Suitable celluloses consist of ca. 500 to 5000 glucose units
and, accordingly, have average molecular weights of 50,000 to 500,000.
According to the invention, cellulose derivatives obtainable from cellulose
by polymer-analog reactions may also be used as cellulose-based
disintegrators. These chemically modified celluloses include, for example,
products of esterification or etherification reactions in which hydroxy
hydrogen atoms have been substituted. However, celluloses in which the
hydroxy groups have been replaced by functional groups that are not
attached by an oxygen atom may also be used as cellulose derivatives.
The group of cellulose derivatives includes, for example, alkali metal
celluloses, carboxymethyl cellulose (CMC), cellulose esters and ethers and
aminocelluloses. The cellulose derivatives mentioned are preferably not
used on their own, but rather in the form of a mixture with cellulose as
CA 02300604 2000-03-10
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
5 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
10 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
15 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
20 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
25 which only attack and completely dissolve the amorphous regions (ca. 30%
of the total cellulose mass) of the celluloses, but leave the crystalline
regions (ca. 70%) undamaged. Subsequent de-aggregation of the
microfine celluloses formed by hydrolysis provides the microcrystalline
celluloses which have primary particle sizes of ca. 5 Nm and which can be
30 compacted, for example, to granules with a mean particle size of 200 Nm.
CA 02300604 2000-03-10
31
According to the present invention, therefore, preferred processes
are those in which the premix to be tabletted additionally contains a
disintegration aid, preferably a cellulose-based disintegration aid,
preferably in granulated, 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 the weight of the premix.
In other preferred processes, the premix additionally contains one or
more substances from the group of bleaching agents, bleach activators,
enzymes, pH regulators, perfumes, perfume carriers, fluorescers, dyes,
foam inhibitors, silicone oils, redeposition inhibitors, optical brighteners,
discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors.
The
substances are described in the following.
Among the compounds yielding H202 in water which serve as
bleaching agents, sodium perborate tetrahydrate and sodium perborate
monohydrate are particularly important. Other useful bleaching agents are,
for example, sodium percarbonate, peroxypyrophosphates, citrate perhy-
drates and H202-yielding peracidic salts or peracids, such as perbenzo-
ates, peroxophthalates, diperazelaic acid, phthaloiminoperacid or diper-
dodecane dioic acid. Even where the bleaching agents are used, there is
no need for surfactants and/or builders so that pure bleach tablets can be
produced. If pure bleach tablets are to be used in the washing of laundry,
a combination of sodium percarbonate and sodium sesquicarbonate is
preferred irrespective of the other ingredients present in the tablets. If
detergent or bleach tablets for dishwashing machines are being produced,
bleaching agents from the group of organic bleaches may also be used.
Typical organic bleaching agents are diacyl peroxides, such as dibenzoyl
peroxide for example. Other typical organic bleaching agents are the
peroxy acids, of which alkyl peroxy acids and aryl peroxy acids are
particularly mentioned as examples. Preferred representatives are (a)
peroxybenzoic acid and ring-substituted derivatives thereof, such as alkyl
CA 02300604 2000-03-10
32
peroxybenzoic acids, but also peroxy-a-naphthoic acid and magnesium
monoperphthalate, (b) aliphatic or substituted aliphatic peroxy acids, such
as peroxylauric acid, peroxystearic acid, s-phthalimidoperoxycaproic acid
[phthaloiminoperoxyhexanoic acid (PAP)], o-carboxybenzamidoperoxy-
caproic acid, N-nonenylamidoperadipic acid and N-nonenylamido-
persuccinates, and (c) aliphatic and araliphatic peroxydicarboxylic acids,
such as 1,12-diperoxycarboxylic acid, 1,9-diperoxyazelaic acid, diperoxy-
sebacic acid, diperoxybrassylic acid, diperoxyphthalic acids, 2-decyldi-
peroxybutane-1,4-dioic acid, N,N-terephthaloyl-di(6-aminopercaproic acid).
Other suitable bleaching agents in dishwasher tablets are chlorine-
and bromine-releasing substances. Suitable chlorine- or bromine-releasing
materials are, for example, heterocyclic N-bromamides and N-chloramides,
for example trichloroisocyanuric acid, tribromoisocyanuric acid, dibromo-
isocyanuric acid and/or dichloroisocyanuric acid (DICA) and/or salts thereof
with cations, such as potassium and sodium. Hydantoin compounds, such
as 1,3-dichloro-5,5-dimethyl hydantoin, are also suitable.
In order to obtain an improved bleaching effect where washing is
carried out at temperatures of 60°C or lower, bleach activators may be
incorporated in the premix. The bleach activators may be compounds
which form aliphatic peroxocarboxylic acids containing preferably 1 to 10
carbon atoms and more preferably 2 to 4 carbon atoms and/or optionally
substituted perbenzoic acid under perhydrolysis conditions. Substances
bearing O- and/or N-acyl groups with the number of carbon atoms
mentioned and/or optionally substituted benzoyl groups are suitable.
Preferred bleach activators are polyacylated alkylenediamines, more
particularly tetraacetyl ethylenediamine (TAED), acylated triazine
derivatives, more particularly 1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine
(DADHT), acylated glycolurils, more particularly tetraacetyl glycoluril
(TAGU), N-acylimides, more particularly N-nonanoyl succinimide (NOSI),
acylated phenol sulfonates, more particularly n-nonanoyl or isononanoyl-
CA 02300604 2000-03-10
33
oxybenzenesulfonate (n- or iso-NOBS), carboxylic anhydrides, more
particularly phthalic anhydride, acylated polyhydric alcohols, more
particularly triacetin, ethylene glycol diacetate and 2,5-diacetoxy-2,5-
dihydrofuran.
In addition to or instead of the conventional bleach activators
mentioned above, so-called bleach catalysts may also be incorporated in
the tablets. Bleach catalysts are bleach-boosting transition metal salts or
transition metal complexes such as, for example, manganese-, iron-,
cobalt-, ruthenium- or molybdenum-salen complexes or carbonyl
complexes. Manganese, iron, cobalt, ruthenium, molybdenum, titanium,
vanadium and copper complexes with nitrogen-containing tripod ligands
and cobalt-, iron-, copper- and ruthenium-ammine complexes may also be
used as bleach catalysts.
Suitable enzymes are those from the class of proteases, lipases,
amylases, cellulases or mixtures thereof. Enzymes obtained from bacterial
strains or fungi, such as Bacillus subtilis, Bacillus licheniformis and
Streptomyces griseus, are particularly suitable. Proteases of the subtilisin
type are preferred, proteases obtained from Bacillus lentus being
particularly preferred. Enzyme mixtures, for example of protease and
amylase or protease and lipase or protease and cellulase or of cellulase
and lipase or of protease, amylase and lipase or of protease, lipase and
cellulase, but especially cellulase-containing mixtures, are of particular
interest. Peroxidases or oxidases have also proved to be suitable in some
cases. The enzymes may be adsorbed to supports and/or encapsulated in
shell-forming substances to protect them against premature decomposition.
The percentage content of the enzymes, enzyme mixtures or enzyme
granules in the tablets according to the invention may be, for example, from
about 0.1 to 5% by weight and is preferably from 0.1 to about 2% by
weight.
In addition, the detergent tablets according to the invention may also
CA 02300604 2000-03-10
34
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-
s 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, based on the nonionic cellulose ether, and the polymers of phthalic
acid and/or terephthalic acid known from the prior art or derivatives thereof,
more particularly polymers of ethylene terephthalates and/or polyethylene
glycol terephthalates or anionically and/or nonionically modified derivatives
thereof. Of these, the sulfonated derivatives of phthalic acid and
terephthalic acid polymers are particularly preferred.
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)-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-chlorostyryl)-4'-(2-sulfostyryl)-diphenyl, 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 with a visually and sensorially "typical and
unmistakable" product. Suitable perfume oils or perfumes include
CA 02300604 2000-03-10
individual perfume compounds, for example synthetic products of the ester,
ether, aldehyde, ketone, alcohol and hydrocarbon type. Perfume com-
pounds of the ester type are, for example, benzyl acetate, phenoxyethyl
isobutyrate, p-tert.butyl cyclohexyl acetate, linalyl acetate, dimethyl benzyl
5 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, citronellyloxyacetal-
10 dehyde, cyclamen aldehyde, hydroxycitronellal, lilial and bourgeonal; the
ketones include, for example, the ionones, a-isomethyl ionone and methyl
cedryl ketone; the alcohols include anethol, citronellol, eugenol, geraniol,
linalool, phenyl ethyl alcohol and terpineol and the hydrocarbons include,
above all, the terpenes, such as limonene and pinene. However, mixtures
15 of various perfumes which together produce an attractive perfume note are
preferably used. Perfume oils such as these may also contain natural
fragrance mixtures obtainable from vegetable sources, for example pine,
citrus, jasmine, patchouli, rose or ylang-ylang oil. Also suitable are clary
oil, camomile oil, clove oil, melissa oil, mint oil, cinnamon leaf oil, lime
20 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 can make up as
25 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
30 through a slower release of the perfume. Suitable support materials are,
CA 02300604 2000-03-10
36
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 difFcult 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.
Before the particulate premix is compressed to form detergent
tablets, it may be "powdered" with fine-particle surface treatment materials.
This can be of advantage to the quality and physical properties of both the
premix (storage, tabletting) and the final detergent tablets. Fine-particle
powdering materials have been known for some time in the art, zeolites,
silicates and other inorganic salts generally being used. However, the
compound is preferably "powdered" with fine-particle zeolite, faujasite
zeolites being preferred. In the context of the present invention, the
expression "faujasite zeolite" 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.
According to the invention, preferred processes for the production of
detergent tablets are those in which the, or one of the, aftertreatment
components subsequently incorporated is a faujasite zeolite with particle
sizes below 100 Nm, preferably below 10 Nm and more preferably below 5
Nm and makes up at least 0.2% by weight, preferably at least 0.5% by
weight and more preferably more than 1 % by weight of the premix to be
tabletted.
The tablets according to the invention are produced by first dry-
CA 02300604 2000-03-10
37
mixing the ingredients - which may be completely or partly pregranulated
and then shaping/forming, morre particularly tabletting, the resulting
mixture using conventional processes. To produce the tablets according to
the invention, the premix is compacted between two punches in a die to
form a solid compactate. This process, which is referred to in short
hereinafter as tabletting, comprises four phases, namely metering,
compacting (elastic deformation), plastic deformation and ejection.
The premix is first introduced into the die, the filling level and hence
the weight and shape of the tablet formed being determined by the position
of the lower punch and the shape of the die. Uniform dosing, even at high
tablet throughputs, is preferably achieved by volumetric dosing of the
compound. As the tabletting process continues, the top punch comes into
contact with the premix and continues descending towards the bottom
punch. During this compaction phase, the particles of the premix are
pressed closer together, the void volume in the filling between the punches
continuously diminishing. The plastic deformation phase in which the
particles coalesce and form the tablet begins from a certain position of the
top punch (and hence from a certain pressure on the premix). Depending
on the physical properties of the premix, its constituent particles are also
partly crushed, the premix sintering at even higher pressures. As the
tabletting rate increases, i.e. at high throughputs, the elastic deformation
phase becomes increasingly shorter so that the tablets formed can have
more or less large voids. In the final step of the tabletting process, the
tablet is forced from the die by the bottom punch and carried away by
following conveyors. At this stage, only the weight of the tablet is
definitively established because the tablets can still change shape and size
as a result of physical processes (re-elongation, crystallographic effects,
cooling, etc.).
The tabletting process is carried out in commercially available tablet
presses which, in principle, may be equipped with single or double
CA 02300604 2000-03-10
38
punches. In the latter case, not only is the top punch used to build up
pressure, the bottom punch also moves towards the top punch during the
tabletting process while the top punch presses downwards. For small
production volumes, it is preferred to use eccentric tablet presses in which
the punches) is/are fixed to an eccentric disc which, in turn, is mounted on
a shaft rotating at a certain speed. The movement of these punches is
comparable with the operation of a conventional four-stroke engine.
Tabletting can be carried out with a top punch and a bottom punch,
although several punches can also be fixed to a single eccentric disc, in
which case the number of die bores is correspondingly increased. The
throughputs of eccentric presses vary according to type from a few hundred
to at most 3,000 tablets per hour.
For larger throughputs, rotary tablet presses are generally used. In
rotary tablet presses, a relatively large number of dies is arranged in a
circle on a so-called die table. The number of dies varies - according to
model - between 6 and 55, although even larger dies are commercially
available. Top and bottom punches are associated with each die on the
die table, the tabletting pressures again being actively built up not only by
the top punch or bottom punch, but also by both punches. The die table
and the punches move about a common vertical axis, the punches being
brought into the filling, compaction, plastic deformation and ejection
positions by means of curved guide rails. At those places where the
punches have to be raised or lowered to a particularly significant extent
(filling, compaction, ejection), these curved guide rails are supported by
additional push-down members, pull-down rails and ejection paths. The die
is filled from a rigidly arranged feed unit, the so-called filling shoe, which
is
connected to a storage container for the premix. The pressure applied to
the premix can be individually adjusted through the tools for the top and
bottom punches, pressure being built up by the rolling of the punch shank
heads past adjustable pressure rollers.
CA 02300604 2000-03-10
39
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, jacketed
and bull's-eye tablets - which have a structure resembling an onion skin -
can also be produced in this way. In the case of bull's-eye tablets, the
upper surface of the core or rather the core layers is not covered and thus
remains visible. Rotary tablet presses can also be equipped with single or
multiple punches so that, for example, an outer circle with 50 bores and an
inner circle with 35 bores can be simultaneously used for tabletting.
Modern rotary tablet presses have throughputs of more than one million
tablets per hour.
Where rotary presses are used for tabletting, it has proved to be of
advantage to carry out the tabletting process with minimal variations in the
weight of the tablets. Variations in tablet hardness can also be reduced in
this way. Minimal variations in weight can be achieved as follows:
- using plastic inserts with minimal thickness tolerances
- low rotor speed
- large filling shoe
- adapting the rotational speed of the filling shoe blade to the rotor speed
- filling shoe with constant powder height
- decoupling the filling shoe from the powder supply
Any of the nonstick coatings known in the art may be used to reduce
caking on the punch. Plastic coatings, plastic inserts or plastic punches are
particularly advantageous. Rotating punches have also proved to be of
advantage; if possible, the upper and lower punches should be designed
for rotation. If rotating punches are used, there will generally be no need
for a plastic insert. In that case, the surfaces of the punch should be
electropolished.
CA 02300604 2000-03-10
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
5 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
10 Holzwarth GbR, Asperg, Wilhelm Fette GmbH, Schwarzenbek, Hofer
GmbH, Weil, KILIAN, Cologne, KOMAGE, Kell am See, KORSCH Pressen
GmbH, Berlin, Mapag Maschinenbau AG, Bern (Switzerland) and Courtoy
N.V., Halle (BE/LU). One example of a particularly suitable tabletting
machine is the model HPF 630 hydraulic double-pressure press
15 manufactured by LAEIS, D.
The tablets can be made in certain shapes and certain sizes.
Suitable shapes are virtually any easy-to-handle shapes, for example
slabs, bars, cubes, squares and corresponding shapes with flat sides and,
in particular, cylindrical forms of circular or oval cross-section. This last
20 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
25 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
30 diameter-to-height ratio of about 0.5:2 to 2:0.5. Commercially available
CA 02300604 2000-03-10
41
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 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
CA 02300604 2000-03-10
42
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 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:
2P
BDt
where c~ represents the diametral fracture stress (DFS) in Pa, P is the force
in N which leads to the pressure applied to the tablet that results in
fracture
thereof, D is the diameter of the tablet in meters and t is its height.
CA 02300604 2000-03-10
43
The present invention also relates to the use of surfactant granules
containing phosphate and faujasite zeolite for improving the hardness and
disintegration time of detergent tablets. This use of the surfactant granules
mentioned in accordance with the invention in the premix leads to tablets
having advantageous properties, as the following Examples show. The
foregoing observations on the process according to the invention apply
similarly to preferred embodiments of the use according to the invention
(quantities of the phosphates and faujasite zeolites, other ingredients,
composition of the premix, etc.).
The use of surfactant granules containing phosphate and nonionic
surfactants for improving the hardness and disintegration time of detergent
tablets is also not described in the prior art. This use is another subject of
the present invention. In this case, too, preferred quantities, etc. can be
found in the foregoing text.
The incorporation of all three constituents (phosphate, faujasite
zeolite and nonionic surfactant) in surfactant granules also leads to
detergent tablets having advantageous properties so that the present
invention also relates to the use of surfactant granules containing
phosphate, faujasite zeolite and nonionic surfactants for improving the
hardness and disintegration time of detergent tablets.
In the use just mentioned, the surfactant granules preferably already
satisfy the criteria fulfilled by detergent tablets according to the
invention,
i.e. the ratio of nonionic surfactants to faujasite zeolite in the surfactant
granules is from 1:20 to 1:1, preferably from 1:15 to 1:1.25, more preferably
from 1:10 to 1:1.5 and most preferably from 1:5 to 1:2.
Examples
Four batches of surfactant granules of which the composition is shown in
Table 1 were produced by wet granulation in a 20-liter Lodige plowshare
mixer. After granulation, the granules were dried in an Aeromatic fluidized
CA 02300604 2000-03-10
44
bed dryer for 30 minutes at an inflowing air temperature of 60°C. After
drying, the granules were sieved to remove the fine particles (< 0.6 mm)
and coarse fractions (> 1.6 mm).
The surfactant granules were then mixed with other components to
form a compressible premix of which the composition is shown in Table 2.
Premixes E1 and E2 according to the invention contained nonionic
surfactant and zeolite X in a ratio by weight of 1:2.25 while the premix of
the Comparison Example C contained a nonionic surfactant and zeolite X
in a ratio of 1.14:1. The premixes were tabletted in a Korsch eccentric
press (tablet diameter 44 mm, tablet height 22 mm, tablet weight 37.5 g).
The measured tablet hardnesses and disintegration times are the mean
values of a double determination, the individual values varying by at most 2
N and 2 s, respectively, according to the type of tablet.
Table 1:
Composition of the surfactant granules [% by weight]
GranulesGranulesGranulesGranules
1 2 3 4
C9_~3 alkyl benzenesulfonate15.1 - 16.8 13.8
C~2_,8 fatty alcohol sulfate4.6 - 5.1 1.0
C,2_,8 fatty alcohol sulfate3.1 30.0 - 8.0
+ 7E0
Soap 1.5 - 1.7 1.5
Zeolite X 7.0 48.0 2.3 7.0
Sodium tripolyphosphate 48.0 - 53.3 48.0
Na hydroxyethane-1,1-diphos-1.2 - 1.3 1.2
phonate
Acrylic acid/maleic acid 3.1 10.0 2.3 3.1
copolymer
NaOH 0.2 - 0.2 0.2
Water, salts Balance Balance Balance Balance
CA 02300604 2000-03-10
Table 2:
Composition of the premixes [% by weight]
E1 E2 C
Surfactant granules 1 (Table 65.0 - _
1)
Surfactant granules 2 (Table - 6.7 -
1)
Surfactant granules 3 (Table - 58.3 -
1)
Surfactant granules 4 (Table - - 65.0
1)
Sodium percarbonate 17.0 17.0 17.0
TAED 5.0 5.0 5.0
Foam inhibitor 2.0 2.0 2.0
Enzymes 2.0 2.0 2.0
Repel-O-Tex~ SRP 4* 1.0 1.0 1.0
Perfume 0.5 0.5 0.5
Wessalith~ P (zeolite A) 2.0 2.0 2.0
Disintegration aid (cellulose)5.5 5.5 5.5
Zeolite X [% by weight in 4.55 4.56 4.55
the premix]
Nonionic surfactant [% by 2.02 2.01 5.2
weight in
the premix]
Ratio of nonionic surfactant 1:2.25 1:2.25 1.14:1
to ~
zeolite X
* Terephthalic acid ethylene glycol polyethylene glycol ester (Rhodia,
Rhone-Poulenc)
The hardness of the tablets was measured after 2 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. The
CA 02300604 2000-03-10
46
experimental data are set out in Table 3:
Table 3:
Detergent tablets [physical data]
Tablet E1 E2 C
Tablet hardness [NJ 40 39 42
Disintegration time 8 12 20
[s]
Tablet hardness [N] 49 53 51
Disintegration time 16 19 35
[s]
Tablet hardness [N] 60 59 62
Disintegration time 23 45 >60
[s]
Table 3 shows that the disintegration times of phosphate-containing
detergent tablets are distinctly reduced by the use of nonionic surfactant
and faujasite zeolite in a certain ratio in accordance with the invention
which provides for distinct improvements, particularly in the case of
relatively hard tablets.
