CA2296239A1 - Abrasion-resistant detergent tablets - Google Patents

Abstract

Detergent tablets which combine high hardness values and extremely short disintegration times with high resistance to abrasion may be obtained by introducing surfactant granules with a water content at least 5% above the water content of the same granules at the equilibrium moisture content into the tablets. The water content can be determined by KF titration at 200°C while the equilibrium moisture content is established by drying the granules at an inflowing air temperature of 80°C and an inflowing air moisture content x of <0.015.

Description

ABRASION-RESISTANT DETERGENT TABLETS
Field of the Invention This invention relates generally to compact shaped bodies having detersive properties. Detersive shaped bodies include, for example, laundry detergent tablets, tablets for dishwashing machines or for cleaning hard surfaces, bleach tablets for use in washing or dishwashing machines, water softening tablets or stain remover tablets. More particularly, the present invention relates to laundry detergent tablets which are used for washing laundry in domestic washing machines and which are referred to in short as detergent tablets.
Background of the Invention Detergent tablets are widely described in the prior-art literature and are enjoying increasing popularity among consumers because they are easy to dose. Tabletted detergents have a number of advantages over powder-form detergents: they are easier to dose and handle and, by virtue of their compact structure, have advantages in regard to storage and transportation. As a result, detergent shaped bodies are also comprehensively described in the patent literature. One problem which repeatedly arises in the use of detergent tablets is the inadequate disintegrating and dissolving rate of the tablets under in-use conditions:
Since sufficiently stable, i.e. dimensionally stable and fracture-resistant, tablets can only be produced by applying relatively high pressures, the ingredients of the tablet are heavily compacted so that disintegration of the tablet in the wash liquor is delayed which results in excessively slow release of the active substances in the washing process. The delayed disintegration of the tablets has the further disadvantage that typical ' 25 detergent tablets cannot be flushed into the washing process from the dispensing compartment of domestic washing machines because the tablets do not disintegrate sufficiently quickly into secondary particles which are small enough to be flushed from the dispensing compartment into the drum of the washing machine. Another problem which occurs with detergent tablets in particular lies in the friability of the tablets and their often inadequate resistance to abrasion. Thus, although sufficiently fracture-resistant, i.e. hard, detergent tablets can be produced, they are often not strong enough to withstand the loads encountered during packaging, transportation and handling, i.e. impact and friction effects, so that broken edges and signs of abrasion spoil the appearance of the tablet or even lead to the complete destruction of its structure.
Many solutions have been developed in the prior art to overcome the dichotomy between hardness, i.e. transportation and handling stability, and easy disintegration of the tablets. One solution known in particular from the field of pharmacy and extended to detergent tablets is to incorporate certain disintegration aids which facilitate the access of water and which swell on contact with water and effervesce or otherwise disintegrate. Other solutions proposed in the patent literature are based on the compression of premixes of certain particle sizes, the separation of individual ingredients from certain other ingredients and the coating of individual ingredients or the entire tablet with binders.
Thus, EP 687 464 (Allphamed Arzneimittel-Gesellschaft) describes effervescent tablets which consist of at least one active principle or a combination of active principles, at least one binder, optionally carriers such as flavors, dyes, pertumes, plasticizers, bleaching agents and effervescent additives, the binders) used being propylene glycol or glycerot, preferably in quantities of 0.004 to 2.5% by weight. Processes for producing these effervescent tablets are also claimed. According to the disclosure of this document, it is also possible through the teaching of the invention to produce an effervescent detergent tablet without the binder used leading to a loss of carbon dioxide from the effervescent additives.
European patent application EP 711 828 (Unilever) describes detergent tablets containing surfactant(s), builders) and a polymer which acts as a binding and disintegration aid. The binders disclosed in this document are said to be solid at room temperature and to be added to the premix to be compressed in the form of a melt. Preferred binders are relatively high molecular weight polyethylene glycols.

i I III I
,. CA 02296239 2000-O1-19 The use of particles containing too little water based on their equilibrium moisture content is described in German patent application DE
197 09 411.2 (Henkel). This document teaches synergistic effects between polyethylene glycols and overdried amorphous silicates.
Known solutions to the problem of the friability or abrasion resistance of detergent tablets are disclosed solely in earlier German patent application DE 198 41 146.4 (Henkel KGaA). The solution proposed therein lies in the incorporation of liquid non-surtactant binders in the premixes to be compressed.
Now, the problem addressed by the present invention was to provide tablets which, for predetermined hardness, would be distinguished by short disintegration times which and, accordingly, could even be flushed into the washing process from the dispensing compartment of commercially available washing machines. In addition to meeting these requirements, the tablets would have increased resistance to impact and friction, i.e.
would show improved, i.e. reduced, friability and would exhibit reduced abrasion behavior.
Brief Description of the Invention It has now been found that the water content of the surfactant granules used in the premixes has a critical influence on the abrasion resistance of the detergent tablets. The use of the surfactant granules mentioned has little effect, if any, on the fracture resistance of the detergent tablets.
The present invention relates to detergent tablets of compacted particulate detergent which contain surfactant granules having 'a water content at least 5% higher than the water content of the same surfactant granules at the equilibrium moisture content.
Detailed Description of the Invention In the context of the present invention, the water 'content of surfactant granules (hereinafter used synonymously with the term "water value") characterizes the percentage by weight of water in the granules as determined at 200°C by Karl Fischer titration (KF titration). The equilibrium moisture content (also referred to hereinafter as the equilibrium moisture) of granules is the water content which is established during drying in a fluidized bed dryer at an inflowing air temperature of 80°C and an inflowing air moisture content x of < 0.015. To determine the equilibrium moisture content, granules are dried under the described conditions and samples thereof are subjected to KF titration at regular intervals. If by doubling the drying time the water value is reduced by less than 2%, the equilibrium moisture content has been reached.
Both the water content at the equilibrium moisture content and the water content of the relatively moist granules to be used in accordance with the invention are based on the particular granules. If a water content of 10% by weight is determined in surfactant granules at the equilibrium moisture content, 100 grams of the granules contain 90 grams of constituents which are not titrated as water in the KF titration at 200°C.
Accordingly, granules having a water value above the water value at the equilibrium moisture content, for example a water value of 11% by weight, contain only 89 g per 100 g granules of constituents which are not titrated as water in the KF titration at 200°C. The above-mentioned value of 5%
by which the water content of the surfactant granules has to be higher in accordande with the invention, i.e. the water value of the same surfactant granules at the equilibrium moisture content, should be regarded as a relative value which is based on the water value at the equilibrium moisture content. In other words, it is not 5 percentage points, but 5 percent relative to the water value at the equilibrium moisture content. In the example mentioned above (water content at equilibrium moisture 10% by weight, based on the granules with equilibrium moisture), therefore, granules to be used in accordance with the invention have water contents above 10.5% by weight, based on the relatively moist granules.
In preferred detergent tablets, the water value of the surfactant granules used in them is higher than the water value of the same surfactant granules at the equilibrium moisture content. Thus, preferred detergent tablets are characterized in that the surfactant granules have a water I IIII

content at least 6%, preferably at least 7.5% and more preferably at least 10% higher than the water content of the same surfactant granules at the equilibrium moisture content.
The water contents of the surfactant granules can vary according to their composition, water values above the equilibrium moisture content being adjustable, for example, through increased addition of water during granulation or by adopting a corresponding procedure in the drying process (residence time, inflowing air temperature). According to the invention, more or less "moist" granules may be used in dependence upon the composition (which is responsible for the equilibrium moisture) and in dependence upon the relative deviation of the water value from the equilibrium moisture. A reference point for variations to the formulation of the surfactant granules can be that preferred detergent tablets are characterized in that the surfactant granules has a water content at the equilibrium moisture content of 5 to 15% by weight, preferably 7.5 to 12.5%
by weight and more preferably 9 to 11 % by weight, based on the surfactant granules.
The water values of the surfactant granules actually used in the detergent tablets according to the invention are at least 5% higher than the above-mentioned water values of the surfactant granules at the equilibrium moisture content. Accordingly, the above mentioned figures have to be multiplied by a factor of >1.05, preferably >1.06, more preferably >1.075 and most preferably >1.1 for the water values of surfactant granules to be used. Accordingly, preferred detergent tablets according to the invention are characterized in that the surfactant granules used have a water content of 5.25 to 16.5% by weight, preferably 7.9 to 18.15% by weight and more preferably 9.45 to 12.1 % by weight, based on the surfactant granules.
According to the teaching of the invention, the surfactant-free components of a detergent tablet may also be used with a water value above the equilibrium moisture content. Abrasion-resistant tablets can also be produced in this way. However, it has been found that the relatively high water value can lead to a deterioration in stability in storage, rni particularly with such components as enzymes, bleaching agents, bleach activators and foam inhibitors. According to the invention, therefore, only the surfactant granules preferably have the elevated water value.
Besides the water present over and above the equilibrium moisture in the surfactant granules in accordance with the invention, the surfactant granules naturally contain surfactants. The surfactants may emanate from the groups of anionic, nonionic, cationic or amphoteric surfactants.
Mixtures of the surfactant types mentioned may of course also be used.
Irrespective of the type of surfactant used, the surfactant granules in preferred detergent tablets have surfactant contents of 5 to fi0% by weight, preferably 10 to 50% by weight and more preferably 15 to 40% by weight, based on the weight of the surfactant granules.
Suitable anionic surfactants are, for example, those of the sulfonate and sulfate type. Suitable surfactants of the sulfonate type are preferably C~.~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 the sulfonation products. Other suitable surfactants of the sulfonate type are the alkane sulfonates obtained from C~2_~8 alkanes, for example by sulfochlorination or sulfoxidation and subsequent hydrolysis or neutralization. The esters of a-sulfofatty acids (ester sulfonates), for example the a-sulfonated methyl esters of hydrogenated coconut oil, palm kernel oil or tallow fatty 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 can-ied 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, rm~

myristic acid, lauric acid, palmitic acid, stearic acid or behenic acid.
Preferred alk(en)yl sulfates are the alkali metal salts and, in particular, the sodium salts of the sulfuric acid semiesters of C~2_~$ fatty alcohols, for example cocofatty alcohol, tallow fatty alcohol, lauryl, myristyl, cetyl or stearyl alcohol, or 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_~s alkyl sulfates, C,2_~5 alkyl sulfates and C~~.~S alkyl sulfates are preferred from the point of view of washing technology. Other suitable anionic surfactants are 2,3-alkyl sulfates which may be produced, for example, in accordance with US
3,234,258 or US 5,075,041 and which are commerially obtainable as products of the Shell OII 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.~8 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 C$_~$ fatty alcohol residues or mixtures thereof. Particularly preferred sulfosuccinates contain a fatty alcohol residue derived from ethoxylated fatty alcohols which, considered in isolation, represent nonionic surfactants (for a description, see below). Of these sulfosuccinates, those of which the fatty alcohol residues are derived from narrow-range ethoxylated fatty alcohols are particularly preferred. Alk(en)yl succinic acid preferably containing 8 to 18 carbon atoms in the alk(en)yl chain or salts thereof may also be used.
Other suitable anionic surfactants are, in particular, soaps. Suitable soaps are saturated fatty acid soaps, such as the salts of lauric acid, myristic acid, palmitic acid, stearic acid, hydrogenated erucic acid and behenic acid, and soap mixtures derived in particular from natural fatty acids, for example coconut oil, palm kernel oil or tallow fatty acids.
The anionic surfactants, including the soaps, may be present in the form of their sodium, potassium or ammonium salts and as soluble salts of organic bases, such as mono-, di- or triethanolamine. The anionic surfactants are preferably present in the form of their sodium or potassium salts and, more preferably, in the form of their sodium salts.
According to the invention, preferred detergents tablets are those in which the surfactant granules contain 5 to 45% by weight, preferably 10 to 40% by weight and more preferably 15 to 35% by weight of anionic surfactants, based on the weight of the surfactant granules.
So far as the choice of anionic surfactants is concerned, there are no basic requirements to restrict the freedom of formulation. However, preferred surfactant granules do have a soap content in excess of 0.2% by weight, based on the total weight of the detergent tablets. Preferred anionic surfactants are alkyl benzenesulfonates and fatty alcohol sulfates;
preferred detergent tablets containing 2 to 20% by weight, preferably 2.5 to 15% by weight and more preferably 5 to 10% by weight of fatty alcohol sulfate(s), based on the weight of the detergent composition.
Preferred nonionic surfactants are alkoxylated, advantageously ethoxylated, more especially primary alcohols preferably containing 8 to 18 carbon atoms and, on average, 1 to 12 moles of ethylene oxide (EO) per mole of alcohol, in which the alcohol component may be linear or, preferably, methyl-branched in the 2-position or may contain linear and methyl-branched residues in the form of the mixtures typically present in oxoalcohol residues. However, alcohol ethoxylates containing linear residues of alcohols of native origin with 12 to 18 carbon atoms, for example coconut oil, palm oil, tallow fatty or oleyl alcohol, and on average 2 i ri 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, C~~~ alcohol containing 7 EO, C~~.~S alcohols containing 3 EO, 5 EO, 7 EO or 8 EO, C~2_~s alcohols containing 3 EO, 5 EO or 7 EO and mixtures thereof, such as mixtures of C~2_~4 alcohol containing 3 EO and C~2_~$ alcohol containing 5 EO. The degrees of ethoxylation mentioned represent statistical mean values which, for a special product, can be a whole number or a broken number. Preferred alcohol ethoxylates have a narrow homolog distribution (narrow range ethoxylates, NRE). In addition to these nonionic surfactants, fatty alcohols containing more than 12 EO
may also be used, examples including tallow fatty alcohol containing 14 EO, 25 EO, 30 EO or 40 EO.
Another class of preferred nonionic surfactants which may be used either as sole nonionic surfactant or in combination with other nonionic surfactants are alkoxylated, preferably ethoxylated or ethoxylated and propoxylated, fatty acid alkyl esters preferably containing 1 ' to 4 carbon atoms in the alkyl chain, more especially the fatty acid methyl esters which are described, for example, in Japanese patent application JP 581217598 or which are preferably produced by the process described in International patent application WO-A-9x113533.
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 may advantageously contain alkyl ,. CA 02296239 2000-O1-19 polyglycosides, APG contents of more than 0.2% by weight, based on the tablet as a whole, being preferred. Particularly preferred detergent tablets contain APGs in quantities of 0.2 to 10% by weight, preferably in quantities of 0.2 to 5% by weight and more preferably in quantities of 0.5 to 3% by weight.
Nonionic surfactants of the amine oxide type, for example N-cocoalkyl-N,N-dimethylamine oxide and N-tallowalkyl-N,N-dihydroxyethyl-amine oxide, and the fatty acid alkanolamide type are also suitable. The quantity in which these nonionic surfactants are used is preferably no more than the quantity in which the ethoxylated fatty alcohols are used and, more preferably, no more than half that quantity.
Other suitable surfactants are polyhydroxyfatty acid amides corresponding to formula (I):
R' R-CO-N-[Z] (I) in which RCO is an aliphatic acyl group containing 6 to 22 carbon atoms, R' is hydrogen, an alkyl or hydroxyalkyl group containing 1 to 4 carbon atoms and [Z] is a linear or branched polyhydroxyalkyl group containing 3 to 10 carbon atoms and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid amides are known substances which may normally be obtained by reductive amination of a reducing sugar with ammonia, an alkylamine or an alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl ester or a fatty acid chloride.
The group of polyhydroxyfatty acid amides also includes compounds corresponding to formula (II):
R'-O-R2 R-CO-N-[Z] (I I) in which R is a linear or branched alkyl or alkenyl group containing 7 to 12 carbon atoms, R' is a linear, branched or cyclic alkyl group or an aryl group containing 2 to 8 carbon atoms and R2 is a linear, branched or cyclic alkyl .. CA 02296239 2000-O1-19 group or an aryl group or an oxyalkyl group containing 1 to 8 carbon atoms, C~.~ alkyl or phenyl groups being preferred, and [Z] is a linear polyhydroxy-alkyl group, of which the alkyl chain is substituted by at least two hydroxyl groups, or alkoxylated, preferably ethoxylated or propoxylated, derivatives of that group.
[Z] is preferably obtained by reductive amination of a reduced sugar, for example glucose, fructose, maltose, lactose, galactose, mannose or xylose. The N-alkoxy- or N-aryloxy-substituted compounds may then be converted into the required polyhydroxyfatty acid amides by reaction with fatty acid methyl esters in the presence of an alkoxide as catalyst, for example in accordance with the teaching of International patent application WO-A-95107331.
According to the invention, preferred detergent tablets are characterized in that the surfactant granules contain 1 to 15% by weight;
preferably 2.5 to 10% by weight and more preferably 5 to 7.5% by weight, based on the weight of the surfactant granules, of nonionic surfactants.
Besides the water present over and above the equilibrium moisture and the surfaetant(s) present in the surfactant granules in accordance with the invention, the surfactant granules generally contain other ingredients of detergents. To obtain storage-stable free-flowing surfactant granules, carriers are preferably added in the production of the surfactant granules, i.e. the surfactant granules preferably contain builders. Other detergent ingredients, more particularly so-called minor components, such as optical brighteners, polymers, defoamers, phosphonates, dyes and perfumes, may also form part of the surfactant granules. These substances are described further below.
The surfactant granules may be used in varying quantities in the detergent tablets according to the invention. Detergent tablets according to the invention which contain the surFactant granules in quantities of 40 to 95% by weight, preferably 45 to 85% by weight and more preferably 55 to 75% by weight, based on the weight of the tablets, are preferred.
The present invention also relates to a process for the production of detergent tablets by mixing surfactant-containing granules with fine-particle after treatment components and then shapingfforming the resulting mixture in known manner, characterized in that the surfactant-containing granules have a water content at least 5% higher than the water content of the same granules at the equilibrium moisture content.
In the process according to the invention, too, the surfactant granules advantageously have a water content of 5.25 to 16.5% by weight, preferably 7.9 to 18.15% by weight and more preferably 9:45 to 12.1 % by weight, based on the surfactant granules.
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 mixe' agglomerators, press agglomeration processes, for example, may also be used. Accordingly, processes in which the surfactant-containing granules are produced by granulation, agglomeration, press aglomeration 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 Machinenfabrik Gustav Eirich, Hardheim), the Schugi~ Flexomix mixer, the ' i un~

Fukae~ FS-G mixers . (trademarks of Fukae Powtech, Kogyo Co., Japan), t_bdige~ FM, KM and CB mixers (trademarks of Lbdige 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 mixeNspheronizer 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 shapinglforming 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 a preferred embodiment of the invention, the surfactant-containing granules are preferably delivered continuously to a planetary roll extruder or to a twin-screw extruder with co-rotating or contra-rotating screws, of which the barrel and the extruderlgranulation head may be heated to the predetermined extrusion temperature. Under the shearing effect of the extruder screws, the premix is compacted under pressure (preferably at least 25 bar or - with extremely high throughputs - even,lower, depending on the machine used), plasticized, extruded in the form of fine strands through the multiple-bore die in the extruder head and, finally, chopped by means of a rotating blade into preferably substantially spherical or cylindrical granules. The bore diameter of the multiple-bore extrusion die and the length to which the extruded strands are cut are adapted to the .. CA 02296239 2000-O1-19 size selected for the granules. In this embodiment, it is possible to produce granules with a substantially uniform predetermined particle size, the absolute particle sizes being adaptable to the particular application envisaged. Important embodiments comprise the production of uniform granules in the millimeter range, for example in the range from 0.8 to 5 mm and, more particularly, in the range from about 1.0 to 3 mm. In one important embodiment, the length-to-diameter ratio of the primary granules formed by cutting the extruded strands is between about 1:1 and about 3:1.
In another preferred embodiment, the still plastic primary granules are subjected to another shaping or forming step in which the edges present on the crude extrudate are rounded off so that spherical or substantially spherical granules can ultimately be obtained. Alternatively, extrusion/
compression can also be carried out in low-pressure extruders, in a Kahl press or in a Bextruder.
In another preferred embodiment of the present invention, the surfactant-containing granules are produced by roll compacting. In this process, the surfactant-containing granules are introduced between two rollers - either smooth or provided with depressions of defined shape - and rolled under pressure between the two rollers to form a sheet-like compactate. The rollers exert a high linear pressure on the premix and may be additionally heated or cooled as required. Where smooth rollers are used, smooth untextured compactate sheets are obtained. By contrast, where textured rollers are used, correspondingly textured compactates or individual pellets, in which for example certain shapes can be imposed in advance on the subsequent granules, can be produced. The sheet-like compactate is then broken up into smaller pieces by a chopping and size-reducing process and can thus. be processed to granules which can be further refined and, more particularly, converted into a substantially spherical shape by further surface treatment processes known per se.
In another preferred embodiment of the present invention, the surfactant-containing granules are produced by pelleting. In this process, the surfactant-containing granules are applied to a perforated surface and .. CA 02296239 2000-O1-19 forced through the perforations by a pressure roller. In conventional pellet presses, the surfactant-containing granules are compacted under pressure, plasticized, forced through a pertorated surface in the form of fine strands by means of a rotating roller and, finally, are size-reduced to granules by a cutting unit. The pressure roller and the perforated die may assume many different forms. For example, flat perforated plates are used, as are concave or convex ring dies through which the material is pressed by one or more pressure rollers. In perforated-plate presses, the pressure rollers may also be conical in shape. In ring die presses, the dies and pressure rollers may rotate in the same direction or in opposite directions. A press suitable for carrying out the process according to the invention is described, for example, in DE-OS 38 16 842 (Schluter GmbH). The ring die press disclosed in this document consists of a rotating ring die permeated by pressure bores and at least one pressure roller operatively connected to the inner surface thereof which presses the material delivered to the die space through the pressure bores into a discharge unit. The ring die and pressure roller are designed to be driven in the same direction which reduces the shear load applied to the premix and hence the increase in temperature which it undergoes. However, the pelleting process may of course also be carried out with heatable or coolable rollers to enable the premix to be adjusted to a required temperature.
The surfactant granules are then mixed with other aftertreatment components to form a premix which may then be compressed to detergent tablets. In addition to the ingredients already mentioned, the premix to be compressed may contain other typical detergent ingredients as aftertreatment components, more particularly from the group of builders, disintegration aids, bleaching agents, bleach activators, enzymes, pH
regulators, fragrances, perfume carriers, fluorescers, dyes, foam inhibitors, silicone oils, redeposition inhibitors, optical brighteners, discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors. However, the substances mentioned, either wholly or in part, may already form part of the surfactant granules.

.- CA 02296239 2000-O1-19 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 compositions according to the invention, including in particular zeolites, silicates, carbonates, organic co-builders and also - providing there are no ecological objections to their use -phosphates.
It has been found that the effect of improving abrasion resistance is greater if the surfactant granules contain only small quantities of carbonates. Accordingly, preferred detergent tablets contain surfactant granules which have a sodium or potassium carbonate content of less than 15% by weight, preferably less than 10% by weight and more preferably less than 5% by weight, based on the surfactant granules.
Suitable crystalline layer-form sodium silicates correspond to the general formula NaMSiXO~+~~ y H20, where M is sodium or hydrogen, x is a number of 1.9 to 4 and y is a number of 0 to 20, preferred values for x being 2, 3 or 4. Crystalline layer silicates such as these are described, for example, in European patent application EP-A-Q 164 514. Preferred crystalline layer silicates corresponding to the above formula are those in which M is sodium and x assumes the value 2 or 3. Both Vii- and 8-sodium disilicates Na2Si205~ y H20 are particularly preferred, ~i-sodium disilicate being obtainable, for example, by the process described in International patent application WO-A- 91108171.
Other useful builders are amorphous sodium silicates with a modulus (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 .. CA 02296239 2000-O1-19 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-4.4 00 024. Compacted amorphous silicates, compounded amorphous silicates and overdried X-ray-amorphous silicates are particularly preferred.
If desired, more zeolite besides. the quantity of zeolite P and/or X
introduced through the surfactant granules may be incorporated in the premix by adding zeolite as an aftertreatment component. The finely crystalline, synthetic zeolite containing bound water used in accordance with the invention is preferably a zeolite of the A, P, X or Y type. 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 pm (volume distribution, as measured by the Coulter Counter Method) and contain preferably 18 to 22% by weight and more preferably 20 to 22% by weight of bound water.
The generally known phosphates may of course also be used as builders providing their use should not be avoided on ecological grounds.
The sodium salts of the orthophosphates, the pyrophosphates and, in particular, the tripolyphosphates are particularly suitable.
Organic cobuilders which may be used in the detergent tablets according to the invention include, in particular, polycarboxy-lateslpolycarboxylic acids, polymeric polycarboxylates, aspartic acid, polyacetals, dextrins, other organic cobuilders (see below) and phosphonates. 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;
adapic 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 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-,. CA 02296239 2000-O1-19 chain polyacrylates which have molecular weights of 2,000 to 10,000 g/mole and, more particularly, 3,000 to 5,000 glmole.
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 acidlmaleic acid copolymers containing 50 to 90% by weight of acrylic acid and 50 to 10% by weight of malefic acid have proved to be particularly suitable. Their relative molecular weights, based on the free acids, are generally in the range from 2,000 to 70,000 glmole, preferably in the range from 20,000 to 50,000 glmole 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 finro 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-4417 734 which preferably contain 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 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 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 andlor glucoheptonic acid.
Other suitable organic builders are dextrins, for example oligomers or polymers of carbohydrates which may be obtained by partial hydrolysis of starches. The hydrolysis may be carried out by standard methods, for example acid- or enzyme-catalyzed methods. The end products are preferably hydrolysis products with average molecular weights of 400 to 500,000 glmole. A polysaccharide with a dextrose equivalent (DE) of 0.5 to 40 and, more particularly, 2 to 30 is preferred, the DE being an accepted measure of the reducing effect of a polysaccharide by comparison with dextrose which has a DE of 100. Both maltodextrins with a DE of 3 to 20 and dry glucose sirups with a DE of 20 to 37 and also so-called yellow dextrins and white dextrins with relatively high molecular weights of 2,000 to 30,000 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-0 472 042 and EP A-a 542 496 and from International patent applications WO A-92/18542, WO A-93108251, WO A-94128030, WO-A-95107303, WO-A-95!12619 and WO-A-95120808. An oxidized oligosaccharide~according to German patent application DE A-196 00 018 is also suitable. A product oxidized at C6 of the saccharide ring can be particularly advantageous.
Other suitable co-builders are oxydisuccinates and other derivatives of disuccinates, preferably ethylenediamine disuccinate. Ethylenediamine-- N,N'-disuccinate (EDDS) is preferably used in the form of its sodium or magnesium salts. Glycerol disuccinates and glycerol trisuccinates are also particularly preferred in this connection. The quantities used in zeolite-containing andlor 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-95!20029.
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 pentarnethylene 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 phosphon~ates, HEDP is preferably used as builder. The aminoalkane phosphonates also show a pronounced heavy metal binding 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.
In order to facilitate the disintegration of heavily compacted tablets, disintegration aids, so-called tablet disintegrators, may be incorporated in them to shorten their disintegration times. According to Rompp (9th Edition, Vol. 6, page 4440) and Voigt "Lehrbuch der pharmazeutischen Technologie" (6th Edition, 1987, pages 182-184), tablet disintegrators or disintegration accelerators are auxiliaries which promote the rapid disintegration of tablets in water or gastric juices and the release of the pharmaceuticals in an absorbable form.
These substances, which are also known as "disintegrators" by virtue of their effect, are capable of undergoing an increase in volume on contact with water so that, on the one hand, their own volume is increased (swelling) and, on the other hand, a pressure can be generated through the release of gases which causes the tablet to disintegrate into relatively small particles. Well-known disintegrators are, for example, carbonatelcitric acid systems, although other organic acids may also be used. Swelling disintegration aids are, for example, synthetic polymers, such as polyvinyl pyrrolidone (PVP), or natural polymers and modified natural substances, such as cellulose and starch and derivatives thereof, alginates or casein derivatives.
Preferred detergent tablets contain 0.5 to 10% by weight, preferably 3 to 7% by weight and more preferably 4 to 6% by weight of one or more disintegration aids, based on the weight of the tablet.
According to the invention, preferred disintegrators are cellulose-based disintegrators, so that preferred detergent tablets contain a cellulose-based disintegrator in quantities of 0.5 to 10% by weight, preferably 3 to 7% by weight and more preferably 4 to 6% by weight. Pure cellulose has the format empirical composition (C6H~o05)" and, formally, is a ~3-1,4-polyacetal of cetlobiose which, in turn, is made up of 2 molecules of glucose. Suitable celluloses consist of ca: 500 to 5000 glucose units and, accordingly, have average molecular weights of 50,000 to 500,000.
According to the invention, cellulose derivatives obtainable from cellulose by polymer-analog reactions may also be used as cellulose-based disintegrators. These chemically mod~ed 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 a celluloses, carboxymethyl cellulose (CMC), cellulose esters and ethers and aminocelluloses. The cellulose derivatives mentioned are preferably not used on their own, but rather in the form of a mixture with cellulose as cellulose-based disintegrators. The content of cellulose derivatives in mixtures such as these is preferably below 50% by weight and more preferably below 20% by weight, based on the cellulose-based disintegrator. In one particularly preferred embodiment, pure cellulose free from cellulose derivatives is used as the cellulose-based disintegrator.
The cellulose used as disintegration aid is preferably not used in fine-particle form, but is converted into a coarser form, for example by granulation or compacting, before it is added to and mixed with the premixes to be tabletted. Detergent tablets which contain granular or optionally co-granulated disintegrators are described in German patent applications DE 197 09 991 (Stefan Herzog) and DE 197 10 254 (Henkel) and in International patent application WO 98140463 (Henkel). Further particulars of the production of granulated, compacted or co-granulated cellulose disintegrators can also be found in these patent applications. The particle sizes of such disintegration aids is mostly above 200 pm, at least 90% by weight of the particles being between 300 and 1600 Nm in size and, more particularly, between 400 and 1200 Nm in size. According to the invention, the above-described relatively coarse-particle cellulose-based disintegrators described in detail in the cited patent applications are preferably used as disintegration aids and are commercially obtainable, for example under the name of Arbocel~ TF-30-HG from Rettenmaier.
Microcrystalline cellulose may be used as another cellulose-based disintegration aid or as part of such a component. This microcrystalline cellulose is obtained by partial hydrolysis of the celluloses under conditions which only attack and completely dissolve the amorphous regions (ca. 30%
of the total cellulose mass) of the celluloses, but leave the crystalline regions (ca. 70%) undamaged. Subsequent de-aggregation of the microfine celluloses formed by hydrolysis provides the microcrystalline celluloses which have primary particle sizes of ca. 5 Nm and which can be , ini compacted, for example, to granules with a mean particle size of 200 Nm.
Among the compounds yielding H202 in water which serve as bleaching agents, sodium perborate tetrahydrate and sodium perborate monohydrate are particularly important. Other useful bleaching agents are, for example, sodium percarbonate, peroxypyrophosphates, citrate perhy drates and H202-yielding peracidic salts or peracids, such as perbenzoates, peroxophthalates, diperazelaic acid, phthaloiminoperacid or diperdodecane dioic acid. Even where 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 orgahic bleaches may also be used. Typical organic bleaching agents are diacyl peroxides, such as dibenzoyl peroxide for example. Other typical organic bleaching agents are the peroxy acids, of which alkyl peroxy acids and aryl peroxy acids are particularly mentioned as examples. Preferred representatives are (a) peroxybenzoic acid and ring-substituted derivatives thereof, such as alkyl peroxybenzoic acids, but also peroxy-oc-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-carboxybenzamido-peroxycaproic acid, N-nonenylamidoperadipic acid and N-nonenylamido-persuccinates. and (c) aliphatic and araliphatic peroxydicarboxylic acids, such as 1,12-diperoxycarboxylic acid, 1,9-diperoxyazelaic acid, diperoxysebacic acid, diperoxybrassylic acid, diperoxyphthalic acids, 2-decyldiperoxybutane-1,4-dioic acid, N,N-terephthaloyl-di(6-aminoper-caproic 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, ' . ' nni .- CA 02296239 2000-O1-19 for example trichloroisocyanuric acid, tribromoisocyanuric acid, dibromo-isocyanuric acid andlor dichloroisocyanuric acid (DICA) and/or salts thereof with rations, 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 detergent tablets according to the invention. 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-aryl 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-dioxohexa-hydro-1,3,5-triazine (DADHT), acylated glycolurils, more particularly tetra-acetyl 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-d iacetoxy-2, 5-d ihyd rofuran.
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 lentos 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 contain components with a positive effect on the removability of oil and fats from textiles by washing (so-called soil repellents). This effect becomes particularly clear when a textile which has already been repeatedly washed with a detergent according to the invention containing this oil- and fat-dissolving component is soiled. Preferred oil- and fat-dissolving components include, for example, nonionic cellulose ethers, such as methyl cellulose and methyl hydroxypropyl cellulose containing 15 to 30% by weight of methoxyl groups and 1 to 15% by weight of hydroxypropoxyl groups, based on the nonionic cellulose ether, and the polymers of phthalic acid andlor terephthalic acid known from the prior art or derivatives thereof, more particularly polymers of ethylene terephthalates and/or polyethylene glycol terephthalates or anionically andlor 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 i'ui' 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 Biphenyl styryl type, for example alkali metal salts of 4,4'-bis-(2-sulfostyryl)-Biphenyl, 4,4'-bis-(4-chloro-3-sulfostyryl)-Biphenyl or 4-(4-chlorostyryl)-4'-(2-sulfostyryl)-Biphenyl, may also be present. Mixtures of the brighteners mentioned above may also be used.
Dyes and fragrances 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 fragrances include individual fragrance compounds, for example synthetic products of the ester, ether, aldehyde, ketone, alcohol and hydrocarbon type. Fragrance compounds of the ester type are, for example, benzyl acetate, phenoxyethyl isobutyrate, p-tert.butyl cyclohexyl acetate, linalyl acetate, dimethyl benzyl carbinyl acetate, phenyl ethyl acetate, linalyl benzoate, benzyl formate, ethyl methyl phenyl glycinate, ally) cyclohexyl propionate, styrallyl propionate and benzy! salicylate. The ethers include, for example, benzyl ethyl ether; the aldehydes include, for example, the linear alkanals containing 8 to 18 carbon atoms, citral; citronellal, citronellyloxy-acetaldehyde, cyclamen aldehyde, hydroxycitronellal, lilial and bourgeonal;
the ketones include, for example, the ionones, a-isomethyl ionone and methyl cedryl ketone; the alcohols include anethol, citronellol, eugenol, geraniol, linalool, phenyl ethyl alcohol and terpineol and the hydrocarbons include, above all, the terpenes, such as limonene and pinene. However, mixtures of various fragrances which together produce an attractive fragrance note are preferably used. Perfume oils such as these may also contain natural fragrance mixtures obtainable from vegetable sources, for example pine, citrus, jasmine, patchouli, rose or ylang-ylang oil. Also suitable are clary oil, camomile oil, nettle oil, melissa oil, mint oil, cinnamon leaf oil; lime blossom oil, juniper berry oil, vetiver oil, olibanum oil, galbanum oil and labdanum oil and orange blossom oil, neroli oil, orange peel oil and sandalwood oil.
The detergent tablets according to the invention normally contain less than 0.01 % by weight of dyes whereas perfumeslfragrances can make up as much as 2% by weight of the formulation as a whole.
The fragrances may be directly incorporated in the detergents according to the invention, although it can also be of advantage to apply the fragrances to supports which strengthen the adherence'of the perfume to the washing and which provide the textiles with a long-lasting fragrance through a slower release of the perfume. Suitable support materials are, for example, cyclodextrins, the cyclodextrinJperfume complexes optionally being coated with other auxiliaries.
In order to improve their aesthetic impression, the detergents according to the invention may be colored with suitable dyes. Preferred dyes, which are not difficult for the expert to choose, have high stability in storage, are not affected by the other ingredients of the detergents or by light and do not have any pronounced substantivity for textile fibers so as not to color them.
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, zeolites of the faujasite type being preferred: In the context of the present invention, the expression "zeolite of the faujasite type" encompasses all three zeolites which form the faujasite subgroup of zeolite structural group 4 (cf. Donald W. Breck: "Zeolite Molecular Sieves" John Wiley & Sons, New York/LondonlSydney/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, fine-particle aftertreatment components subsequently incorporated is a zeolite of the faujasite type 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 compressed.
In preferred processes according to the invention, the premix to be compressed has a bulk density of at least 500 g/l, preferably of at least 600 gll and more preferably above 700 gAl and additionally contains one or more substances from the group of bleaching agents, bleach acivtators, disintegration aids, enzymes, pH regulators, fragrances, perfume carriers, fluorescers, dyes, foam inhibitors, silicone oils, redeposition inhibitors, optical brigtheners, discoloration inhibitors, dye transfer inhibitors and corrosion inhib~ors.
To produce the tablets according to the invention, the premix is compacted between two punches in a die to form a solid compactate. This process, which is referred to in short hereinafter as tabletting, comprises four phases, namely metering, compacting (elastic deformation), plastic deformation and ejection.
The premix is first introduced into the die, the filling level and hence the weight and shape of the tablet formed being determined by the position of the lower punch and the shape of the die. Uniform metering, even at high tablet throughputs, is preferably achieved by volumetric metering of the 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 in~

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) islare 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.
Tabtetting 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 VIII

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 compound. The pressure applied to the compound can be individually adjusted through the tools for the top and bottom punches, pressure being built up by the rolling of the punch shank heads past adjustable pressure rollers.
To increase throughput, rotary presses can also be equipped with two filling shoes so that only half a circle has to be negotiated to produce a tablet. To produce two-layer or multiple-layer tablets, several filling shoes are arranged one behind the other without the lightly compacted first layer being ejected before further filling.. Given suitable process control, shell and bull's-eye tablets - which have a structure resembling an onion skin -can also be produced in this way. In the case of bull's-eye tablets, the upper surface of the core or rather the core layers is not covered and thus 20, 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, KILIAN, Cologne, KOMAGE, Kell am See, KORSCH Pressen GmbH, Berlin, Mapag Maschinenbau AG, Bern (Switzerland) and Courtoy N.V., Halle {BE/LU). One example of a particularly suitable tabletting machine is the model HPF 630 hydraulic double-pressure press manufactured by LAEIS, D.

nn ~ CA 02296239 2000-O1-19 The tablets can be made in certain shapes and certain sizes.
Suitable shapes are virtually any easy-to-handle shapes, for example slabs, bars, cubes, squares and corresponding shapes with flat sides and, in particular, cylindrical forms of circular or oval cross-section. This last embodiment encompasses shapes from tablets to compact cylinders with a height-to-diameter ratio of more than 1.
The portioned pressings may be formed as separate individual elements which correspond to a predetermined dose of the detergent.
However, it is also possible to form pressings which combine several such units in a single pressing, smaller portioned units being easy to break off in particular through the provision of predetermined weak spots. For the use of laundry detergents in machines of the standard European type with horizontally arranged mechanics, it can be of advantage to produce the portioned pressings as cylindrical or square tablets, preferably with a diameter-to-height ratio of about 0.5:2 to 2:0.5. Commercially available hydraulic presses, eccentric presses and rotary presses are particularly suitable for the production of pressinigs 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 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. Muftilayer 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 diamefral fracture stress. This in turn can be determined in accordance with the following equation:

o=
~Dt where a represents the diametral fracture stress (DFS) in Pa, P is the force in the N which leads to the pressure applied to the tablet that results in fracture thereof, D is the diameter of the tablet in meters and t is its height.
The present invention also relates to the use of surfactant granules which have a water content at least 5% higher than the water content of the same surfactant granules at the equilibrium moisture content and which, after mixing with fine-particle aftertreatment components, are compressed in known manner to form detergent tablets for improving the stability and solubility of detergent tablets. Through the use of the surfactant granules which are more moist than their equilibrium moisture content and which are compressed to form detergent tablets after mixing with other components, the physical properties of the tablets can be improved, as shown by the following Examples:

Examples A surtactant-containing tower powder used as a basis for surfactant-containing granules was produced by spray drying. The tower powder was granulated with other components (zeolite, FAS granules, nonionic surtactant, polymer) in a 130-liter Ltidige plowshare mixer. The quantities of solids and liquids used and the order in which they were introduced into the mixer are shown in Table 2.
After granulation, the granules were dried in an Aeromatic fluidized bed dryer at an inflowing air temperature of 80°~ and an inflowing air moisture content x of 0.008. For the three drying times of 10, 20 and 40 minutes, a 30 kg granulation batch was divided into 10 kg drying batches to rule out any falsification of the results by different wet granules. After drying, the granules with drying times of 10 minutes (E) and 20 minutes (V}
were sieved to remove the fine particles (< 0.06 mm) and coarse fractions (> 1.6 mm). The water content of the granules as a function of the drying time was determined by Karl-Fischer titration at 200°C and is shown in Table 3.
The surtactant granules E and V were then mixed with other components to form a compressible premix which was then tabletted in a Korsch eccentric press (tablet diameter 44 mm, height 22 mm, weight 37.5 g). The tabletting pressure was adjusted so that two series of tablets (E1, E2 and V1,V2) differing in their hardness were obtained. 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. The composition of the spray-dried tower powder is shown in Table 1 while the composition of the premixes to be tabletted (and hence the tablets) is shown in Table 4.

Table 1: Composition of the spray-dried tower powder [% by weight) C9_~3 alkyl benzenesulfonate 22.8 C~2_~6 tallow alcohol + 5 EO 1.3 Soap 1.3 Sodium sulfate 4.0 Zeolite A 48.0 Na hydroxyethane-1,1-diphosphonate1.0 Acrylic acidlmaleEC acid copolymer8.0 NaOH, water-free active substance0.5 Water, salts Balance Table 2: Granulation mixture ~F~~ ~Sqi2 t; ':. 4 ( ~-~F'~r:S~T
~~, . .:x . ~ ~ , '::9 ~ ~ ~ ~ 34~' ,"F , ..x. .~'a.': ~ ,..:
a''a~yg ~t2..,.~~ a l3Fq, " , < ~~ :,~ F~F
i z~,3 ,_<~:- ''~ .~~i ~'3~.xu~ i e:' ~ ~Tjde-..':' Ff~.a ". X73, ~~~t .>. OFF . f.,a':. ~f9 ~ .~ sF . '~.9~q~.H~r,.;
a ~~~ . a+,.:?. ~. 7L t ~~.F
~ F : Fa~ 4~5 g ~I "f ka; -:.; II F i~il ~ '~ 5 ~;' ~ :.
3 ;~'~~ ~,' < ..' ' ~ ~

, ; ~ ~
j. i:. ~ ~ Ih ~ .... ~ Is~z E~- ~~~
F ~ .t ~ 1 . ~ ~ ~ ~' ~ ~-k ~ ~ t ~ : ~~~ : ~~ ~ , 3,., ~f F r... ~! ~~ ..:~I i ~ ~
~

I
~
~
~

, ~ [
, S ~ ,~
C~e d " ~q . a ~'F~~S
.'.~~Y,.: 5~ ~,.,~
kj,~~F ..,<tj~ "y 's,~ ', 8~~,~x:
j a ~ 3: , ~ 3~$t n..4 ~ x,~_>.... I:
F~ ~ ~~

Tower powder (Table 1 ) 82 ~

C~2_~g fatty alcohol sulfate 5.0 1 granules*

C~2_~g fatty alcohol + 7 EO 4.0 2 Acrylic acidlmaleic acid copolymer**2.0 3 Water 2.0 4 Wessalith~P (zeolite A) 5.0 5 * composition:92% by weight C~2_~8 fatty alcohol sulfate 3% by weight sodium carbonate balance water, salts ** 40% in water I III I

Table 3: Water content of the surfactant granules after drying ;a ~ ~F~ #a' .. I d 3 YIk ~ y # ~"~T~F~~~~-:.
x 3 . F~: 1~' ~ ~ , ,~ a~;~ : F
kr s w .:k3%t ' rbF$# _ _~~('~ ~~~5~;s..F,~~. #~
~j da; :: '~ :<r ~~~ , E '~ ~
~ ~~>$ s,~.-3,~h # ,. 3 .~~~~es, ~~ I~~: ~~ k~ a'3L. ~
#P~ F~~ k~ ~<"c- ..: ; ~ ., 4..yu~#k' e~' s~~, ~; :" 3i ~~tk~ 3,, ~fi;;.. ~ ,.~'.,.F ~~~'~.
;d~ ~:#S a3~~ Isl..: ~, a ~"w $d~.. '~. ~.:.~ ~d3~~_,, s .~ . ~ 3t7~...., #~ ,~ _. ~'". F 3 ,.U
~.w ~ k5r'..~ x3~.:',2I~,v3S~t3E~,.,..~~ ,~du~;:3, i:.
Is" F3 P #, ss'#.~~#f 3:v., ~ L,'. ~,. , t~. ~ ,. i~i ##t... ; , ~,: S s- #qai5 S~
, "sIIk, ~8,. ,s, t ;...s a ~,., . T s", s , ,";q k~s. /3'ss Drying time in mins.10 20 , Water value [%] 11.1 10.0 9.9 Equilibrium moistureNo Yes Yes The water value of the granules E according to the invention was thus 11 % above the equilibrium moisture content.
Table 4: Composition of the premixes [% by weight]
Surfactant granules (Table62.05 2) Sodium perborate monohydrate17.4 TAED 7.3 Foam inhibitor 3.5 Enzymes 1.7 Repel-O-Text SRP 4* 1.1 Perfume 0.45 Wessalith~P (zeolite A) 1.0 Disintegration aid (cellulose)5.5 * terephthalic acid/ethylene glycol/polyethylene glycol ester (Rhodia, Rhone-Poulenc) The hardness of the tablets was measured after two days' storage by deforming a tablet until it broke, the force being applied to the sides of the tablet and the maximum force withstood by the tablet being determined.
To determine tablet disintegration, a tablet was placed in a glass beaker filled with water (600 ml water, temperature 30°C) and the time taken by the tablet to disintegrate completely was measured.
Abrasion resistance was determined by placing a tablet on a 1.6 mm mesh sieve. The sieve was then placed in a Retsch analytical sieving rnu machine and stressed at an amplitude of 2 mm for 120 seconds. The abrasion in % can be calculated by weighing the tablet on the sieve before and after stressing. The experimental data are shown in Table 5:
Table 5: Detergent tablets [physical data]
~~~b,~~~ ~t~~ ~ ~~~t-,~~. t ;~-~, X302~ ~t ~ ~~~~ y4 '~. ~t. ~P.i ~ ~~~ ~.
~ ~ ~ ~ r~g~'~~i~~~
,c1- f .,~.. "'.g. .~~~3~~~~~S ~,~~~~S,Is~~~,,!~~, 3 ~ ~~ ~ , I~$~. ~1~.~, E~~jg'41 ~ijg,,"..,~f~~sz~, i~ 1~'f~,. ~ ~ ~F 40 ,y;T.?ia .~ ..:~i~ ~,~'(~g;~s~~~~k~FS~~~~t , p;~ ~Ff~ .aJq(= 71~~ ]
~ ,.,~~~~~,,.~', 30 31 Tablet hardness [N

Tablet disintegration9 10 12 11 [s]

Abrasion [%] 10 65 6 17 Whereas the hardnesses and disintegration times of tablets E and V
are of the same order, the tablets E according to the invention show far better resistance to the friction effect of the vibrating sieve. The performance properties are thus further improved by the use of the relatively moist surFactant granules in accordance with the invention.

Claims (20)

1. A detergent tablet comprising compacted particulate surfactant granules with a water content at least 5% higher than the water content of the same surfactant granules at an equilibrium moisture content.

2. The detergent tablet as claimed in claim 1, wherein the surfactant granules have a water content at least 6% higher than the water content of the same surfactant granules at the equilibrium moisture content.

3. The detergent tablet as claimed in claim 1, wherein the surfactant granules have a water content at the equilibrium moisture content of 5 to 15% by weight, based on the surfactant granules.

4. The detergent tablet as claimed in claim 1, wherein the surfactant granules have a water content of 5.25 to 18.15% by weight, based on the surfactant granules.

5. The detergent tablet as claimed in claim 1, wherein the surfactant granules have a surfactant content of 5 to 60% by weight, based on the weight of the surfactant granules.

6. The detergent tablet as claimed in claim 1, wherein the surfactant granules contain 5 to 45% by weight, based on the weight of the surfactant granules, of anionic surfactants.

7. The detergent tablet as claimed in claim 1, wherein the surfactant granules contain 1 to 15% by weight, based on the weight of the surfactant granules, of nonionic surfactants.

8. The detergent tablet as claimed in claim 1, wherein the surfactant granules contain less than 15% by weight, based on the weight of the surfactant granules, of sodium and/or potassium carbonate.

9. The detergent tablet as claimed in claim 1, containing the surfactant granules in quantities of 40 to 95% by weight, based on the weight of the tablet.

10. A process for the production of detergent tablets comprising; mixing surfactant-containing granules with fine-particle aftertreatment components to form a premix and subsequent forming/shaping the premix in known manner wherein the surfactant-containing granules have a water content at least 5% higher than the water content of the same surfactant granules at the equilibrium moisture content.

11. The process as claimed in claim 10, wherein the surfactant granules have a water content of 5.25 to 18.15% by weight, based on the surfactant granules.

12. The process as claimed in claim 10, wherein the surfactant-containing granules are produced by a process selected from the group consisting of granulation, agglomeration, press agglomeration or a combination of these processes.

13. The process as claimed in claim 10, wherein the premix to be tabletted has a bulk density of at least 500 g/l.

14. The process as claimed in claim 10, wherein the premix to be tabletted additionally contains at least one substance selected from the group consisting of bleaching agents, bleach activators, disintegration aids, enzymes, pH regulators, fragrances, perfume carriers, fluorescers, dyes, foam inhibitors, silicone oils, redeposition inhibitors, optical brighteners, discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors.

15. In a process for forming detergent tablets by mixing surfactant granules with fine-particle aftertreatment components, to form a premix and compressing the premix to form detergent tablets the improvement which comprises increasing stability and solubility of detergent tablets by using surfactant granules having a water content at least 5% higher than the water content of the same surfactant granules at an equilibrium moisture content.

16. The detergent tablet of claim 7 wherein the surfactant granules have a water content at least 7.5% higher than the water content of the same surfactant granules at the equilibrium moisture content.

17. The detergent tablet of claim 2 wherein the surfactant granules have a water content at least 10% higher than the water content of the same surfactant granules at the equilibrium moisture content.

18. The detergent tablet of claim 1 wherein the surfactant granules have a water content of from 7.9% to 16.5% by weight based on the weight of the surfactant granules.

19. The process of claim 11 wherein the surfactant granules have a water content of 7.9% to 16.5% by weight based on the weight of the surfactant granules.

20. The detergent tablet of claim 1 wherein the surfactant granules comprise:

a) from 5% to 60% by weight of surfactant;
b) from 5.25% to 18.15% by weight of water; and c) less than 10% by weight of sodium or potassium carbonate;
and d) at least one member selected from the group consisting of bleaching agents, bleach activators, disintegration aids, enzymes, pH regulators, fragrances, perfume carriers, fluorescers, dyes, foam inhibitors, silicon oils, redeposition inhibitors, optical brighteners, discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors.