CA2302811A1 - Method for producing stable and rapidly dissolving washing detergent tablets - Google Patents

Abstract

A process for the production of detergent tablets by mixing detergent granules and powder-form pretreatment components containing a faujasite zeolite and optionally zeolite X, and tabletting the resulting mixture, optionally under pressures of 100 to 1,000 N/cm2 and at temperatures of 10 to 80°C, wherein the mixture comprises 0.5% to 5% by weight of the faujasite zeolite and optionally 0.5% to 5% by weight of the zeolite X, based on the weight of the tablet formed.

Description

Method for Producing Stable and Rapidly Dissolving Washing Detergent Tablets Field of the Invention This invention relates to the production of detergent tablets. More particularly, the invention relates to a process for the production of detersive tablets which can be obtained by tabletting particulate detergent compositions and which are distinguished by high strengths and, at the same time, good disintegrating and dissolving properties.
Background of the Invention Detersive 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 tabl~etting, the mixture to be tabletted is tabletted directly, i.e.
without preliminay 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.
The normal method of producing detergent tablets starts out from powder-form components ("primary particles") which are agglomerated or granulated by suitable methods to form secondary particles with a larger particle diameter. 'These granules or mixtures of different granules are then mixed with individual additives and tabletted. The properties of the granules are crucially important to the physical properties of the tablets -particle sizes, moisture content and other parameters which can be controlled in the granules contribute significantly to the ultimate properties of the tablets. l'wo physical properties of tablets in particular are of decisive importance, especially in the case of detergent tablets, namely:
hardness and disintegration rate. Whereas stable tablets can be obtained by applying correspondingly high tabletting pressures, the time the tablets take to disintegrate increases dramatically with increasing tabletting pressure. Since the required properties of a hard, transportable and handling-resistant tablet on the one hand and a rapidly disintegrating tablet on the other hand are mutually conflicting, the production of detergent tablets is generally attended by the problem of overcoming the dichotomy between hardness and disintegration as far as possible.
The production of detergent tablets is widely described in the prior art, the main emphasis in the patent literature being on certain compositions or on the distribution of certain ingredients throughout the tablet.
Thus, EP-A-0 522 766 (Unilever) discloses tablets of a compacted particulate detergent composition containing surfactants, builders and disintegration aids (for example based on cellulose), the particles being at least partly coated with the disintegrator which has both a binder effect and a disintegrating effect when the tablets are dissolved in water. The document in question also refers to the general difficulty of producing tablets which combine adequate stability with good dissolvability. The particle size in the mixture to be tabletted is said to be above 200 Nm, the upper and lower limits to the individual particle sizes differing by no more than 700 Nm fronn one another. The tablets are produced by mixing detergent granules formed in known manner with powder-form treatment components and tabletting the resulting mixture.
Other docurnents cancerned with the production of detergent tablets are EP-A-0 716 144 (Unilever), which describes tablets with an external coating of water-soluble material, and EP-A-0 711 827 (Unilever) where one of the tablet ingredients is a citrate with a certain solubility.
The use of binders optionally developing a disintegrating effect (particularly polyethylene glycol) is disclosed in EP-A-0 711 828 (Unilever) which describes detergent tablets made by tabletting a particulate detergent composition at temperatures between 28°C and the melting point of the binder, the tabletting process always being carried out below the melting temperature. It is clear from the Examples of this document that the tablets produced in accordance with its teaching have higher fracture resistance values where tabletting is carried out at elevated temperature.
Detergent tablets in which individual ingredients present are separated from one another are also described in EP-A-0 481 793 (Unilever). The detergent tablets disclosed in this document contain sodium percarbonate which is spatially separated from all other components that could affect its stability.
The process mentioned in the prior art for the production of detersive tablets is tabletting which, in some cases, is carried out at different temperatures. Other influencing factors mentioned in the prior art are merely physical properties of the mixture to be tabletted such as, for example, particle size, the spatial distribution of individual ingredients or physical properties of individual ingredients.
The "powdering" of granules is well-known in the prior art. The fine-particle materials used for powdering include, above all, inorganic salts, for example sodium sulfate or carbonate, sodium silicates and aluminium silicates and organic substances, such as polymeric polycarboxylates.
Granules are powdered both to reduce their tackiness and to increase their bulk density which can lead to performance-related advantages. The addition of fine-particle powdering materials to mixtures of granules and powders and the effects of this on the properties of the powdered mixtures are not described in the prior art.
Nowhere in the prior art is it explained how the selective pretreatment of the particulate detergent composition to be tabletted before the tabletting proc:ess can benefit the physical properties of the resulting detergent tablets.
Now, the problem addressed by the present invention was to find another influencing factor - besides the selection of individual ingredients -with which the physical properties of detergent tablets could be improved.
In particular, the problem addressed by the present invention was to provide a process which would give hard but rapidly dissolving detergent tablets through selective pretreatment of the mixture to be tabletted.
Summary of the Invention It has now been found that the use of certain zeolites for powdering in the production of the particulate detergent composition to be tabletted, particularly during mixing of the granular components with the powder-form mixing components, gives tablets that combine high hardness with good disintegrating properties.
Accordingly, the present invention relates to a process for the production of detergent tablets by mixing detergent granules formed in known manner with powder-form pretreatment components and tabletting the resulting mixture, characterized in that 0.5 to 5% by weight of a faujasite zeolite, based on the weight of the tablet formed, is added to the mixture to be tabletted as the powder-form pretreatment component.
In another aspect, the invention provides a detergent tablet formulation comprising detergent granules and powder-form pretreatment components, wherein the pretreatment component comprises from 0.5% to 5% by weight of a faujasite zeolite, based on the weight of the tablet formed.
Detailed Description of the Invention The zeolite added as a powder-form powdering component before tabletting of the mixture has the general formula Mv"O ~ AI2O3 ~ x Si02 ~ y HZO, 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 5 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 SiO4 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". Varioua different zeolites can be produced from these building units. At the present time, 34 natural zeolite minerals and approximately 100 synthetic zeolites are known.
The most well-known zeolite, zeolite 4 A, is a cubic assemblage of ~i-cages connectecl 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~2[(A102),2(Si02y~2] ~ 27 H20.
According io the invention, faujasite zeolites are used in the detergent tablets according to the invention, their use affording distinct and unexpected advantages so far as the disintegrating and dissolving properties of the dEaergent tablets are concerned.
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 [3-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)»] ~ 264 H20. 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, 1 i'7).
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 or 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 advantages of the process according to the invention coming to light particularly clearly when at least 50% of the powdering material consists of a faujasite zeolite. In another possible embodiment, for example, the minimum quantity of a faujasite zeolite (0.5%

by weight, based on the weight of the tablet formed) is used with conventional zeolite A making up the remainder of the powdering material.
At all events, however, the powdering material preferably consists entirely of one of more fau~asite zeolites, zeolite X being preferred.
The aluminium silicates used in the process according to the 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:
Na8sI(AIO2)e~s(Si02)~osl ~ x H20, Ka6I(AIO2)86I,SIO2)1~] - x H20, Ca4oNasl(A102)8s(Si02)~osl ~ x H20, Sr2~Ba?2I(A102)ss(Si02)~osl ~ x H20, in which x may assume a value of 0 to 276 and which have pore sizes of 8.0 to 8.4 A.
For example, a co-crystallizate of zeolite X and zeolite A (ca. 80% by weight zeolite X), ~nrhich is marketed by CONDEA Augusta S.p.A. under the name of VEGOBO~ND AX'S and which may be described by the following formula:
nNa20 ~ (1-n)K20 ~ A1203 ~ (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:
Na5sI(A102),s(Si02)~ss1 ~ x H20, Kssl(A102)ss~Si02)~ssl ~ x H20, in which x is a number of 0 to 276 and which have pore sizes of 8.0 A.
The particle sizes of the faujasite zeolites used in the process according to the invention are in the range from 0.1 to 100 Nm, preferably in the range from 0.5 to 50 Nm and more preferably in the range from 1 to 30 Nm, as measured by standard methods for determining particle size.
The actual production of the tablets according to the invention is carried out by first dry-mixing the granular ingredients and the powder-form ingredients and tlhen shaping/forming, more particularly tabletting, the resulting mixture using canventional processes. To produce the tablets according to the invention, the premix prepared by the process according to the invention is compacted between two punches in a die to form a solid compactate. This. process, which is referred to in short hereinafter as tabletting, comprises four phases, namely metering, compacting (elastic deformation), plastic deformation and ejection.
The premix is first introduced into the die, the filling level and hence the weight and shape of the tablet formed being determined by the position of the lower punch and the shape of the die. Uniform dosing, even at high tablet throughputs, is preferably achieved by volumetric dosing of the premix. As the tabletting process continues, the top punch comes into contact with the premix and continues descending towards the bottom punch. During this compaction phase, the particles of the premix are pressed closer together, the void volume in the filling between the punches continuously diminishing. The plastic deformation phase in which the particles coalesce .and form the tablet begins from a certain position of the top punch (and hence from a certain pressure on the premix). Depending on the physical properties of the premix, its constituent particles are also partly crushed, the premix sintering at even higher pressures. As the tabletting rate increases, i.e. at high throughputs, the elastic deformation phase becomes increasingly shorter so that the tablets formed can have more or less large voids. In the final step of the tabletting process, the tablet is forced from the die by the bottom punch and carried away by following conveyors. At this stage, only the weight of the tablet is definitively established because the tablets can still change shape and size as a result of physical processes (re-elongation, crystallographic effects, cooling, etc.).
The tabletting process is carried out in commercially available tablet presses which, in principle, may be equipped with single or double punches. In the (latter case, not only is the top punch used to build up pressure, the bottom punch also moves towards the top punch during the tabletting process while the top punch presses downwards. For small production volumes, it is preferred to use eccentric tablet presses in which the punches) is/are fixed to an eccentric disc which, in turn, is mounted on a shaft rotating at a certain speed. The movement of these punches is comparable with the operation of a conventional four-stroke engine.
Tabletting can be carried out with a top punch and a bottom punch, although several punches can also be fixed to a single eccentric disc, in which case the number of die bores is correspondingly increased. The throughputs of eccentric presses vary according to type from a few hundred to at most 3,000 tablets per hour.
For larger throughputs, rotary tablet presses are generally used. In rotary tablet presses, a relatively large number of dies is arranged in a circle on a so-called die table. The number of dies varies - according to model - between 6 and 55, although even larger dies are commercially available. Top and bottom punches are associated with each die on the die table, the tabletting pressures again being actively built up not only by the top punch or bottom punch, but also by both punches. The die table and the punches move about a common vertical axis, the punches being brought into the filling, compaction, plastic deformation and ejection 5 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 10 connected to a storage cantainer 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, 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.
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, KILIA,N, Cologne, KOMAGE, Kell am See, KORSCH Pressen GmbH, Berlin, Mapag Maschinenbau AG, Bern (Switzerland) and Courtoy N.V., Halle (BE/LU). One example of a particularly suitable tabletting machine is the model HPF 630 hydraulic double-pressure press manufactured by LAEIS, D.
The tablets can be made in certain shapes and certain sizes.
Suitable shapes .are virtually any easy-to-handle shapes, for example slabs, bars, cubes, squares and corresponding shapes with flat sides and, in particular, cylindrical forms of circular or oval cross-section. This last embodiment encornpasses shapes from tablets to compact cylinders with a height-to-diameter ratio of more than, particularly uniform density distribution in the tablets being obtained where the diameter-to-height ratio is about 4:1.
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 to use the detergent tablets in conjunction with a dosing aid.

Another preferred tablet which can be produced has a plate-like or slab-like structure with alternately thick long segments and thin short segments, so that individual segments can be broken off from this "bar" at the predetermined weak spots, which the short thin segments represent, and introduced into the machine. This "bar" principle can also be embodied in other geometric forms, for example vertical triangles which are only joined to one .another at one of their longitudinal sides.
In another possible embodiment, however, the various components are not compressed to form a single tablet, instead the tablets obtained comprise several Layers, i.e. at least two layers. These various layers may have different dissolving rates. This can provide the tablets with favorable performance properties. If, for example, the tablets contain components which adversely affect one another, one component may be integrated in the more quickly dissolving layer while the other component may be incorporated in a more slowly dissolving layer so that the first component can already have reacted off by the time the second component dissolves.
The various layers of the tablets can be arranged in the form of a stack, in which case the inner layers) dissolve at the edges of the tablet before the outer layers have completely dissolved. Alternatively, however, the inner layers) may also be completely surrounded by the layers lying further to the outside which prevents constituents of the inner layers) from dissolving prematurely.
In another preferred embodiment of the invention, a tablet consists of at least three layers, i.e. two outer layers and at least one inner layer, a peroxy bleaching agent being present in at least one of the inner layers whereas, in the case of the stack-like tablet, the two cover layers and, in the case of the envelope-like tablet, the outermost layers are free from peroxy bleaching agent. In another possible embodiment, peroxy 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. tUlultilayer 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.
If multiphase or multilayer tablets are produced, each individual layer consists of a compacted premix which has been mixed with faujasite zeolite in accordance with the invention. This gives the best disintegration times coupled with good tablet hardness values. However, the procedure according to the invention of preparing a premix need not of course be applied in individual regions, inserts or layers of the tablets so that the dissolving of those regions is retarded, resulting in controlled-release effects.
Similar effects can also be obtained by coating individual constituents of the detergent composition to be tabletted 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 tabletting, the detergent tablets have high stability. The fracture resistance of cylindrical tablets can be determined via the diametral fracture stress. This in turn can be determined in accordance with the following equation:

a--~Dt where a represents the diametral fracture stress (DFS) in Pa, P is the force in N which leads to~ the pressure applied to the tablet that results in fracture thereof, D is the diameter of the tablet in meters and t is its height.
In preferred embodiments of the process according to the invention, the mixture of granules, powder-form pretreatment components and faujasite zeolite to be tabletted is tabletted under pressures of 100 to 1,000 N/cm2, preferably 200 to 800 N/cm2 and more preferably 250 to 500 N/cm2 and at temperatures of 10 to 80°C, preferably 15 to 70°C and more preferably 20 to 60°C.
The most important ingredients of detergent tablets which may be used in the process according to the invention both in the granules and as powder-form treatment components are briefly described in the following.
The granular constituents of the mixture to be tabletted are produced in known manner with compositions known per se, the choice of the ingredients being determined by the particular purpose envisaged for the tablets.
Anionic, nonionic, cationic and/or amphoteric surfactants may be used in the detergent tablets according to the invention. Mixtures of anionic and nonionic surfactants in which the anionic surfactants should outweigh the nonionic surfactants are preferred from the applicational 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.
Suitable anionic surfactants are, for example, those of the sulfonate and sulfate type. preferred surfactants of the sulfonate type are C9_~3 alkyl benzenesulfonates, olefin sulfonates, i.e. mixtures of alkene and hydroxy alkane sulfonates, and the disulfonates obtained, for example, from C~2-18 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 o~r sulfoxidation and subsequent hydrolysis or neutral-ization. The ester;> 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 5 with 1 to 3 moles of fatty acid or in the transesterification of triglycerides with 0.3 to 2 moles of glycerol. Preferred sulfonated fatty acid glycerol esters are the sulfonation products of saturated fatty acids containing 6 to 22 carbon atoms, for example caproic acid, caprylic acid, capric acid, myristic acid, lauric; acid, palmitic acid, stearic acid or behenic acid.
10 Preferred alk(en)yl sulfates are the alkali metal salts and, in particular, the sodium salts of the sulfuric acid semiesters of C~2_~8 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 15 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_~~; 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 ethoxylated with 1 to 6 moles of ethylene oxide, such as 2-methyl-branched C~~ ~ alcohols containing on average 3.5 moles of ethylene oxide (EO) or C~2_~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 suitat~le 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 Cg-18 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 suitak>le anionic surfactants are, in particular, soaps. Suitable soaps are saturated fatty acid soaps, such as the salts of lauric acid, myristic acid, palrnitic 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.
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-~a alcohols containing 3 EO, 5 EO or 7 EO and mixtures thereof, such as mixtures of C~2_~4 alcohol containing 3 EO and C~2_~$ alcohol containing 5 EO. The degrees of ethoxylation mentioned represent statistical mean values which, for a special product, can be a whole number or a broken number. Preferred alcohol ethoxylates have a narrow homolog distribution (narrow range ethoxylates, NRE). In addition to these nonionic surfactants, fatty alcohols containing more than 12 EO may also be used, examples including tallow alcohol containing 14 EO, 25 EO, 30 EO or 40 EO.
Other nonionic surfactants which may be used are alkyl glycosides with the general formula RO(G)X where R is a primary, linear or methyl-branched, more particularly 2-methyl-branched, aliphatic radical containing 8 to 22 and preferably 12 to 18 carbon atoms and G stands for a glycose unit containing 5 or 6 carbon atoms, preferably glucose. The degree of oligomerization x, which indicates the distribution of monoglycosides and oligoglycosides, is a number of 1 to 10; 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 especially the fatty acid methyl esters which are described, for example, in Japanese patent application JP 58/217598 or which are preferably produced by the process described in International patent application MIO-A-90113533.
Nonionic surfactants of the amine oxide type, for example N-coconutalkyl-N,N-dimethylamine oxide and N-tallowalkyl-N,N-dihydroxy-ethylamine oxide, and the fatty acid alkanolamide type are also suitable.

The quantity in which these nonionic surfactants are used is preferably no more than the quantity in which the ethoxylated fatty alcohols are used and, more preferably, no more than half that quantity.
Other suitable surfactants are polyhydroxyfatty acid amides corresponding to formula (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 atom s and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid amides are known substances which may normally be obtained by reductive aminatioin of a reducing sugar with ammonia, an alkylamine or an alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl ester or a fatty acid chloride.
The group of polyhydroxyfatty acid amides also includes compounds corresponding to formula (II):
R'-O-R2 R-CO-N-[Z] (I I) in which R is a linear or branched alkyl or alkenyl group containing 7 to 12 carbon atoms, R' is a linear, branched or cyclic alkyl group or an aryl group containing 2 to 8 carbon atoms and R2 is a linear, branched or cyclic alkyl group or an aryl group or an oxyalkyl group containing 1 to 8 carbon atoms, C~~ alkyl or phenyll groups being preferred, and [Z] is a linear polyhydroxy-alkyl group, of which the alkyl chain is substituted by at least two hydroxyl groups, or alkoxylated, preferably ethoxylated or propoxylated, derivatives of that group.

[Z] is preferably obtained by reductive amination of a reduced sugar, for example glucose, fructose, maltose, lactose, galactose, mannose or xylose. The N-alkoxy- or N-aryloxy-substituted compounds may then be converted into the required polyhydroxyfatty acid amides by reaction with fatty acid methyl esters in the presence of an alkoxide as catalyst, for example in accordance with the teaching of International patent application WO-A-95107331.
Builders which may be present in the detergent tablets according to the invention include in particular silicates, aluminium silicates (particularly zeolites), carbonates, salts of organic di- and polycarboxylic acids and mixtures of these substances.
Suitable, crystalline layer-form sodium silicates correspond to the general formula NaMSiX02x+~~ y H20, where M is sodium or hydrogen, x is a number of 1.9 to 4 and y is a number of 0 to 20, preferred values for x being 2, 3 or 4. Crystalline layer silicates such as these are described, for example, in European patent application EP-A-0 164 514. Preferred crystalline layer sillicates corresponding to the above formula are those in which M is sodium and x assumes the value 2 or 3. Both [3- and 8-sodium disilicates Na2Si2C)5~ y H20 are particularly preferred, [3-sodium disilicate being obtainable, for example, by the process described in International patent application TWO-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-ra~~ 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 5 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 10 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.
The finely crystalline, synthetic zeolite containing bound water used 15 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 ~; and mixtures and/or co-crystallizates of A, X and/or P, for example a co-c;rystallizate of 0% zeolite X and 20% zeolite A which is marketed under the name of VEGOBOND AX~ (by CONDEA Augusta 20 S.p.A.), are also suitable. The zeolite may be used in the form of a spray-dried powder or even in the form of an undried stabilized suspension still moist from its production. Where the zeolite is used in the form of a suspension, the suspension may contain small additions of nonionic surfactants as stabilizers, for example 1 to 3% by weight, based on zeolite, of ethoxylated C~2_,8 fatty alcohols containing 2 to 5 ethylene oxide groups, C~2_~4 fatty alcohols containing 4 to 5 ethylene oxide groups or ethoxylated isotridecanols. Suitable zeolites have a mean particle size of less than 10 ~m (volume distribution, as measured by the Coulter Counter Method) and contain preferably 18 to 22% by weight and more preferably 20 to 22% by weight of bound water.

The generally known phosphates may of course also be used as builders providing their use should not be avoided on ecological grounds.
The sodium salts of the orthophosphates, the pyrophosphates and, in particular, the tripolyphosphates are particularly suitable.
Useful organic builders are, for example, the polycarboxylic acids usable, for example, in the form of their sodium salts, such as citric acid, adipic acid, succinic acid, glutaric acid, tartaric acid, sugar acids, amino-carboxylic 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. These salts are used for their builder properties and should not be regarded as part of the effervescent aystem, especially since the salts are not able, for example, to release carbon dioxide from hydrogen carbonates.
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.
In order to obtain an improved bleaching effect where washing is carried out at temperatures of 60°C or lower, bleach activators may be incorporated in the detergent tablets. The bleach activators may be compounds which form aliphatic peroxocarboxylic acids containing preferably 1 to 10 carbon atoms and more preferably 2 to 4 carbon atoms and/or optionally substituted perbenzoic acid under perhydrolysis conditions. Substances bearing O- and/or N-acyl groups with the number of carbon atoms mentioned and/or optionally substituted benzoyl groups are suitable. Preferred bleach activators are polyacylated alkylene-diamines, more particularly tetraacetyl ethylenediamine (TAED), acylated triazine derivatives, more particularly 1,5-diacetyl-2,4-dioxohexahydro-1,3;5-triazine (DADHT), acylated glycolurils, more particularly tetraacetyl glycoluril (TAGU), N-acylimides, more particularly N-nonanoyl succinimide (NOSI), acylated phenol sulfonates, more particularly n-nonanoyl or isononanoyloxybenzenesulfonate (n- or iso-NOBS), carboxylic anhydrides, more particularly phthalic anhydride, acylated polyhydric alcohols, more particularly triacetin, ethylene glycol diacetate and 2,5-diacetoxy-2,5-dihydrofuran.
In addition to or instead of the conventional bleach activators mentioned above, so-called bleach catalysts may also be incorporated in the tablets. Bleach catalysts are bleach-boosting transition metal salts or transition metal complexes such as, for example, manganese-, iron-, cobalt-, ruthenium- or molybdenum-salen complexes or carbonyl complexes. Manganese, iron, cobalt, ruthenium, molybdenum, titanium, vanadium and copper complexes with nitrogen-containing tripod ligands and cobalt-, iron-, copper- and ruthenium-ammine complexes may also be used as bleach catalysts.
Suitable foam inhibitors are, for example, soaps of natural or synthetic origin which have a high percentage content Of C~g_24 fatty acids.
Suitable non-surface-active foam inhibitors are, for example, organopolysiloxanes and mixtures thereof with microfine, optionally silanized, silica or bis-stearyl ethylenediamide. Mixtures of different foam inhibitors, for example mixtures of silicones, paraffins and waxes, may also be used with advantage. The foam inhibitors are preferably fixed to a granular water-soluble or water-dispersible support. Mixtures of paraffins and bis-stearyl eth~ylenediamides are particularly preferred.
In addition, irhe detergent tablets according to the invention may also contain components with a positive effect on the removability of oil and fats from textiles by washing (so-called soil repellents). This effect becomes particularly clear Hrhen 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, 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 theae, the sulfonated derivatives of phthalic acid and terephthalic acid polymers are particularly preferred.
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 tabNets 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.
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. llAixtures 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 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.lbutyl cyclohexyl acetate, linalyl acetate, dimethyl benzyl carbinyl acetate, phenyl ethyl acetate, linalyl benzoate, benzyl formate, ethyl methyl phenyl glycinate, allyl cyclohexyl propionate, styrallyl propionate and benzyl salicylate. The ethers include, for example, benzyl ethyl ether; the aldehydes include, for example, the linear alkanals containing 8 to 18 carbon atoms, citral, citronellal, citronellyloxyacetal-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 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 blossom oil, juniper berry oil, vetiver oil, olibanum oil, galbanum oil and 5 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 much as 2% by weight of the formulation as a whole.
Examples To produce detergent tablets, detergent granules (composition as shown in Table 1) were introduced into a mixer, sprayed with perfume and then mixed with the treatment components listed in Table 2. 4% by weight of cellulose (disintegrator) and 1 % by weight of powdering component -based on the weiight of the tablet to be formed - were added before tabletting. Zeolite X was used in tablets 1 according to the invention while Comparison Examples 2 contained zeolite A as powdering material.
Comparison Examples 3 and 4 contained silicas as powdering material, the mixture being mixed with a hydrophobic precipitated silica (Sipernat~ D 17, Degussa AG) in Example 3 and with a hydrophilic precipitated silica (Sipernat~ 22 LS, IDegussa AG) in Example 4.

Table 1:
Composition of the' surfactant granules [% by weight]
Cg_~3 Alkyl benzenesulfonate 18.4 C~2_~$ Fatty alcohol sulfate 4.9 C~2_~g Fatty alcohol + 7E0 4.9 Soap 1.6 Zeolite A 31.3 Sodium carbonate 18.8 Sodium silicate 5.5 Acrylic acid/maleic acid copolymer5.5 Opt. brightener 0.3 Salts/water Balance Table 2:
Composition of the detergent tablets [% by weight]
Surfactant granule, 65.2 Perfume 0.5 Sodium perborate 16.0 Tetraacetyl ethylenediamine 7.3 (TAED) Foam inhibitor 3.5 Enzymes 2.5 Cellulose 4.0 Zeolite A or zeolite X 1.0 Salts/water Balance The hardness of the tablets (diameter: 44 mm) was measured by deforming a tablet until it broke, the force being applied to the sides of the tablet and the maximum force withstood by the tablet being determined.
For the hardness and disintegration tests and for determining residue behavior, two series of tablets 1 according to the invention and of comparison tablets 2 to 4 were prepared at different tabletting pressures as reflected in the finio different tablet hardnesses shown in Table 3 in the columns of the particular Examples.
To determine tablet disintegration, one 40 g tablet was placed in a glass beaker filleal with water (600 ml water, temperature 30°C) and the time taken by thE: tablet to disintegrate completely without mechanical assistance was measured.
To determine residue behavior, three 40 g tablets were placed in the dispensing compartment of the particular washing machine. After the dispensing or flushing-in phase, the residue in the compartment was dried and weighed.
The experimental data are set out in Table 3.
Table 3:
Detergent tablets [physical data]
Tablet Example Example Example Example (invention) (comparison) (comparison) (comparison) Pressure 4.8 5.9 4.8 5.9 4.9 5.9 4.7 6.0 kN kN kN kN kN kN kN kN

applied Tablet 25 35 25 35 27 35 24 37 N N N N N N N N

hardness Tablet 6 sec 10 11 21 9 sec 19 12 14 sec sec sec sec sec sec disintegration Residue - - - - 3 g 23 4 g 36 g g The invention may be varied in any number of ways as would be apparent to a person skilled in the art and all obvious equivalents and the like are meant to fall within the scope of this description and claims.
The description is meant to serve as a guide to interpret the claims and not to limit them unnec;essarily.

Claims (17)

1. A process for the production of detergent tablets, comprising the steps of mixing detergent granules and powder-form pretreatment components, and tabletting the resulting mixture, wherein from 0.5% to 5%
by weight of a faujasite zeolite, based on the weight of the tablet formed is added to the mixture to be tabletted as the powder-form pretreatment component.

2. A process as claimed in claim 1, wherein from 1 % to 4% by weight of the faujasite zeolite is added to the mixture to be tabletted.

3. A process as claimed in claim 1 or 2, wherein the faujasite zeolite added to the mixture to be tabletted has particle sizes in the range from 0.1 to 100 µm as measured by standard methods for determining particle size.

4. A process as claimed in any of claims 1 to 3, wherein from 0.5% to 5% by weight of zeolite X is added to the mixture to be tabletted.

5. A process as claimed in any of claims 1 to 4, wherein the mixture of the detergent granules and the powder-form pretreatment components comprising faujasite zeolite is tabletted under pressures of 100 to 1,000 N/cm2 and at temperatures of 10 to 80°C.

6. A process as claimed in claim 5, wherein from 1.5% to 2.5%
by weight of the faujasite zeolite is added.

7. A process as claimed in any one of claims 1 to 6, wherein the faujasite zeolite added to the mixture to be tabletted has particle sizes in the range 0.5 to 50 µm.

8. A process as claimed in claim 7, wherein the faujasite zeolite added to the mixture to be tabletted has particle sizes in the range 1 to 30 µm.

9. A process as claimed in any one of claims 1 to 8, wherein from 1 % to 4% by weight of zeolite X is added to the mixture to be tabletted.

10. A process as claimed in claim 9, wherein from 1.5% to 2.5%
by weight of zeolite X is added to the mixture to be tabletted.

11. A process as claimed in any one of claims 1 to 10, wherein the mixture of the detergent granules and the powder-form pretreatment components comprising faujasite zeolite is tabletted under pressures of 200 to 800 N/cm2 and at temperatures 15 to 70°C.

12. A process as claimed in claim 11, wherein the mixture of the detergent granules and the powder-form pretreatment components comprising faujasite zeolite is tabletted under pressures of 250 to 500 N/cm2 and at temperatures 20 to 60°C.

13. A process for the production of detergent tablets, comprising the steps of mixing detergent granules and powder-form pretreatment components, and tabletting the resulting mixture under pressures of 100 to 1,000 N/cm2 and at temperatures of 10 to 80°C, wherein from 0.5% to 5%
by weight of faujasite zeolite and 0.5% to 5% by weight of zeolite X are added as powder-form pretreatment components, based on the weight of the tablet formed.

14. A process as claimed in claim 13, wherein the tabletting of the mixture is preformed under pressures of 200 to 800 N/cm2 and at temperatures of 15 to 70°C, and the powder-form pretreatment components comprise from 1 % to 4% by weight of faujasite zeolite and 1 to 4% by weight of zeolite X, based on the weight of the tablet formed.

15. A process as claimed in claim 14, wherein the tabletting is performed under pressures of 250 to 500 N/cm2 and at temperatures of 20 to 60°C, and the mixture comprises 1.5% to 2.5% by weight of faujasite zeolite and 1.5% to 2.5% by weight of zeolite X, based on the weight of the tablet formed.

16. A detergent tablet formulation comprising detergent granules and powder-form pretreatment components, wherein the pretreatment component comprises from 0.5% to 5% by weight of a faujasite zeolite, based on the weight of the tablet formed.

17. A detergent formulation as claimed in claim 16 wherein the pretreatment components are as defined in any one of claims 1 to 15.