CA2303638A1

CA2303638A1 - Single- or multi-phase detergent tablets containing special bleach activators

Info

Publication number: CA2303638A1
Application number: CA002303638A
Authority: CA
Inventors: Joerg Poethkow; Horst-Dieter Speckmann; Andreas Lietzmann; Monika Boecker; Christian Nitsch
Original assignee: Henkel AG and Co KGaA
Current assignee: Individual
Priority date: 1999-03-31
Filing date: 2000-03-31
Publication date: 2000-09-30
Also published as: ES2255995T3; DE19914812A1; KR20010110469A; WO2000060035A3; EP1165742A2; DE50012128D1; EP1165742B1; WO2000060035A2; JP2002541302A; AU3814200A

Abstract

Detergent tablets combining high bleaching performance with short disintegration times, despite high hardness values, contain as bleach activator cationic nitrites corresponding to formula (I):
(see formula I) in which R1 represents -H, -CH3, a C2-24 alkyl or alkenyl group, a substituted C2-24 alkyl or alkenyl group with at least one substituent from the group consisting of -Cl, -Br, -OH, -NH2, -CN, an alkyl or alkenyl aryl group containing a C1-24 alkyl group or a substituted alkyl or alkenyl aryl group containing a C1-24 alkyl group and at least one other substituent at the aromatic ring, R2 ad R3 independently of one another are selected from -CH2-CN, -CH3, -CH2-CH3, -CH2-CH2-CH3, -CH(CH3)-CH3, -CH2-OH, -CH2-CH2-OH, -CH(OH)-CH3, -CH2-CH2-CH2-OH, -CH2-CH(OH)-CH3, -CH(OH)-CH2-CH3, -(CH2CH2-O)n H where n = 1, 2, 3, 4, 5 or 6 and X is an anion, the pH value of a 1 % by weight aqueous solution of the tablet or the phase containing the nitriloquat being below 10.

Description

Single- or Multi-phase Detergent Tablets Containing Special Bleach Activators Field of the Invention This invention relates to detergent tablets which contain so-called nitriloquats as bleach activators. More particularly, the invention relates to laundry detergent tablets, cleaning tablets, more particularly dishwasher tablets, bleach tablets and water softener tablets containing these bleach activators.
Background of the Invention Detergent compositions in the form of tablets have long been known and are widely described in the prior art although, hitherto, tablets have not been especially prominent on the market. The reason for this is that tablets, despite a number of advantages, also have disadvantages which have an adverse effect both on their production and use and on their acceptance by consumers. The main advantages of tablets, such as elimination of the need to measure out the quantity of product required by the consumer, the higher density and hence the reduced packaging and storage costs and an aesthetic aspect which should not be underestimated, are offset by such disadvantages as the dichotomy between acceptable hardness and sufficiently rapid disintegration and dissolution of the tablets and numerous technological difficulties in production and packaging.
In particular, the dichotomy between a sufficiently hard tablet and a sufficiently fast disintegration time is a central problem. Since sufficiently stable, i.e. dimensionally stable and fracture-resistant, tablets can only be produced by applying relatively high tabletting pressures, the tablet ingredients are heavily compacted which delays disintegration of the tablet in the aqueous wash liquor and hence leads to excessively slow release of the active substances in the washing process. The delayed disintegration of the tablets has the further disadvantage that conventional 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 into the drum of the washing machine from the dispensing compartment.
Many proposals have been put forward in the prior art with a view to overcoming the dichotomy between hardness, i.e. transportation and handling stability, and easy disintegration of the tablets. One proposed solution which is known in particular from the pharmaceutical field and which has been extended to detergent tablets is to incorporate certain disintegration aids which facilitate the access of water or which have a swelling or effervescing or other disintegrating effect on contact with water.
Other proposed solutions from the patent literature include the tabletting of premixes with certain particle sizes, the separation of individual ingredients from certain other ingredients and the coating of individual ingredients or the tablet as a whole with binders.
Bleaching compositions which contain bleach activators of the nitriloquat type are described in the prior art. Thus, European patent application EP 303 520 (Kao Corp.) discloses bleaching compositions which contain a peroxide and a per acid precursor containing at least one N+-CH2-CN or one N+(CH2CN)2 group. Detergent tablets are not mentioned in this document.
European patent application EP 458 396 (Unilever) also describes bleaching compositions which contain a peroxy bleaching agent and a per acid precursor containing at least one N+-CH2-CN or N+(CH2CN)2 group.
This document also makes no reference either to particle sizes or to detergent tablets.
Cationic nitrites with the general formula R'R"R"'N+CR'R2-CN and their use as a bleach activator are described in European patent application EP 464 880 (Unilever). This document also makes no refer-ence whatever to detergent tablets.

Detergent tablets in which individual ingredients are separated from others are described, for example, in EP-A-0 481 793 (Unilever). The detergent tablets disclosed in this document contain sodium percarbonate which is separated from all other components that could affect its stability (for example bleach activators). Bleach activators of the nitriloquat type are not mentioned in this document nor does it provide any information on the pH values of the solutions of individual layers or the tablet as a whole.
None of the cited prior art documents which are concerned with detergent tablets describes detergent tablets containing bleach activators based on "nitriloquats". Nowhere is their any indication of a well-defined particle size range for tablets or regions of tablets containing bleach activators based on nitriloquats. None of the documents cited above is concerned with improving the solubility of detergent tablets by the selective use of these special bleach activators in regions with a defined pH value.
Accordingly, the problem addressed by the present invention was to provide detergent tablets which would contain so-called nitriloquats as bleach activators and which would combine high hardness with excellent disintegration properties. The detergent tablets provided by the invention would also be able to be dosed from the dispensing compartment without the consumer experiencing any disadvantages through residues in the dispensing compartment and too little detergent in the wash liquor.
Besides these tablet-specific properties, the cleaning performance of the tablets according to the invention would also be exemplary. In particular, the storage stability of the tablets and the maintenance of their bleaching performance, even after prolonger storage, would be guaranteed.
Summary of the Invention It has now been found that the stability of bleach activators based on "nitriloquats" in detergent tablets can be increased by using these bleach activators in tablets or regions of tablets which, after dissolution in water, have a pH value below 10.

The present invention relates to single- or multi-phase detergent tablets of compacted particulate detergent containing bleaching agents, bleach activators) and optionally other detergent ingredients, characterized in that the the tablets or at least one phase thereof contains) as bleach activator a cationic nitrite corresponding to formula (I):
R' R2- i ~+~-(CH2)-CN X~-~ (I) in which R' represents -H, -CH3, a C2_24 alkyl or alkenyl group, a substituted C2_24 alkyl or alkenyl group with at least one substituent from the group consisting of -CI, -Br, -OH, -NH2, -CN, an alkyl or alkenyl aryl group containing a C~_24 alkyl group or a substituted alkyl or alkenyl aryl group containing a C~_24 alkyl group and at least one other substituent at the aromatic ring, R2 ad R3 independently of one another are selected from -CH2-CN, -CH3, -CH2-CH3, -CH2-CH2-CH3, -CH(CH3)-CH3, -CHZ-OH, -CH2-CH2-OH, -CH(OH)-CH3, -CH2-CH2-CH2-OH, -CHZ-CH(OH)-CH3, -CH(OH)-CH2-CH3, -(CH2CH2-O)~H where n = 1, 2, 3, 4, 5 or 6 and X is an anion, the pH value of a 1 % by weight aqueous solution of the tablet or the phase containing the nitriloquat being below 10.
Detergent tablets according to the invention may be single- or multi-phase tablets. According to the invention, the individual phases of the tablet may have various three-dimensional forms. The most simple form is a two-layer or multilayer tablet where each layer of the tablet represents a phase. However, it is also possible in accordance with the invention to produce multiphase tablets where individual phases are in the form of incorporations in (an)other phase(s). Besides so-called ring/core tablets, jacket tablets, for example, or combinations of the tablet forms mentioned above are possible. Examples of multiphase tablets can be found in the drawings of EP-A-0 055 100 (Jeyes) which describes lavatory cleaning blocks. At present, the most widespread form of multiphase tablets are two-layer or multilayer tablets. According to the present invention, therefore, the phases of the tablet are preferably in the form of layers.

5 According to the invention, two-, three- and four-layer tablets are preferred.
Detailed Description of the Invention According to the invention, the pH value of a 1 % by weight aqueous solution can be determined by preparing a solution of the tablet or the phase containing the cationic nitrite of formula (I) in demineralized water.
To this end, a corresponding quantity of the tablet or the phase is dissolved or suspended in water and the pH value is determined in known manner using indicator papers or glass rods. Since certain methods for determining pH are temperature-dependent, the values mentioned throughout the present specification apply to a temperature of the solution or suspension of 20°C.
In preferred single-phase or multi-phase detergent tablets, the pH
value of a 1 % by weight aqueous solution of the tablet or the phase containing the nitriloquat is below 9, preferably below 8, more preferably below 7 and most preferably below 6.
Within the pH range mentioned, single- or multi-phase detergent tablets where the pH of a 1 % by weight aqueous solution of the tablet or the phase containing the nitriloquat is below 6.5, preferably below 6, more preferably below 5.5 and most preferably below 5 are preferred.
The tablets according to the invention may contain the cationic nitrites corresponding to general formula (I) in varying quantities, the quantity being determined by the application envisaged for the tablets.
Thus, laundry detergent tablets and dishwasher tablets normally contain less bleach activator than, for example, bleach tablets which consist largely of bleaching agent and bleach activator. According to the invention, preferred detergent tablets are characterized in that they contain the cationic nitrite corresponding to formula (I) in quantities of 0.1 to 20% by weight, preferably in quantities of 0.25 to 15% by weight and more preferably in quantities of 0.5 to 10% by weight, based on the weight of the tablet.
In one particularly preferred embodiment, the detergent tablets according to the invention contain the cationic nitrite corresponding to formula (I) in relatively coarse form. In preferred detergent tablets, at least 90% by weight of the particles of the cationic nitrite corresponding to formula (I) are larger than 0.2 mm in size.
In another preferred embodiment of the invention, not only are more than 90% by weight of the particles of the cationic nitrite larger than 0.2 mm in size, a large percentage of even coarser particles is also present. Pre-ferred detergent tablets are characterized in that at least 40% by weight, preferably at least 50% by weight and more preferably at least 60% by weight of the particles of the cationic nitrite corresponding to formula (I) are larger than 0.4 mm in size.
The percentage of particles larger than 200 Nm in size should preferably be more than 90% by weight, based on all the particles of the cationic nitrite. In order to have an advantageous homogeneous particle size distribution, the bleach activators used should above all be free from overly fine particles or dust, i.e. in one particularly preferred embodiment should not contain any particles smaller than 0.2 mm in diameter. In particularly preferred detergent tablets, the cationic nitrites are substantially free from particles below 0.2 mm in size. "Substantially free" in the context of the present invention means contents below 2% by weight, preferably below 1 % by weight and more preferably below 0.5% by weight, based on the particles as a whole.
In particularly preferred detergent tablets, the cationic nitrite corresponding to formula (I) has a mean particle size above 400 Nm, preferably above 500 Nm, more preferably above 600 Nm and most preferably above 700 Nm.
General formula (I) encompasses a number of cationic nitrites which may be used in accordance with the present invention. In one particularly advantageous embodiment, the detergent tablets according to the invention contain cationic nitrites in which R' stands for methyl, ethyl, propyl, isopropyl or an n-butyl, n-hexyl, n-octyl, n-decyl, n-dodecyl, n-tetra-decyl, n-hexadecyl or n-octadecyl group. R2 and R3 are preferably selected from methyl, ethyl, propyl, isopropyl and hydroxyethyl; one or both of these substituents may with advantage even be a cyanomethylene group. In the following Table, preferred cationic nitrites corresponding to formula (I) are characterized by their substituents R', R2 and R3:
R _ R

_H -CHs _CH3 _H _CH2_CHs _CHs -H _CH2_CH2_CHs _CHs -H -CH(CH3)-CH3 -CH3 -H -CH(OH)-CH3 -CH3 -H -CH2-CH(OH)-CH3 -CH3 -H -CH(OH)-CH2-CH3 -CH3 -H -(CHZCH2-O)~H -CHs -H -(CH2CH2-O)2H -CHs -H -(CHzCH2-O)sH -CH3 -H -(CHZCHZ-O)aH -CHs -H -(CH2CH2-O)sH -CHs -H -(CH2CH2-O)sH -CHs -CHs -CHs -CHs -CH3 -CH(CH3)-CH3 -CH3 -CH3 -CH(OH)-CH3 -CH3 -CH3 -CH2-CH(OH)-CH3 -CH3 -CH3 -CH(OH)-CH2-CH3 -CH3 -CH3 -(CH2CH2-O)~H -CH3 -CHs -(CHZCH2-O)zH -CHs -CHs -(CH2CH2-O)sH -CHs -CHs -(CH2CH2-O)aH -CHa -CHs -(CH2CH2-O)sH -CHs -CHs -(CH2CHz-O)sH -CHs -CHZ-CH3 -CH(CH3)-CH3 -CH3 -CH2-CH3 -CH(OH)-CH3 -CH3 -CH2-CH3 -CH2-CH(OH)-CH3 -CH3 -CH2-CH3 -CH(OH)-CH2-CH3 -CH3 -CH2-CH3 -CH(CH3)-CH3 -CH2-CH3 -CH2-CH3 -CH(OH)-CH3 -CH2-CH3 -CHZ-CH3 -CH2-CH(OH)-CH3 -CHZ-CH3 ' -CH2-CH3 -CH(OH)-CH2-CH3 -CH2-CH3 -CHZ-CH2-CH3 -CH(CH3)-CH3 -CH3 -CH2-CH2-CH3 -CH(OH)-CH3 -CH3 -CH2-CH2-CH3 -CH2-CH(OH)-CH3 -CH3 -CH2-CH2-CH3 -CH(OH)-CH2-CH3 -CH3 -CH2-CH2-CH3 -CH(CH3)-CH3 -CH2-CH3 -CHZ-CHZ-CHs -CH2-OH -CHZ-CH3 -CH2-CH2-CH3 -CH(OH)-CH3 -CH2-CH3 -CH2-CH2-CH3 -CH2-CH(OH)-CH3 -CH2-CH3 -CH2-CH2-CH3 -CH(OH)-CH2-CH3 -CH2-CH3 -CH(CH3)-CH3 -CH(CH3)-CH3 -CH3 -CH(CH3)-CH3 -CH2-OH -CH3 -CH(CH3)-CH3 -CH2-CH2-OH -CH3 -CH(CH3)-CH3 -CH(OH)-CH3 -CH3 -CH(CH3)-CH3 -CH2-CH2-CHz-OH -CH3 -CH(CH3)-CH3 -CH2-CH(OH)-CH3 -CH3 -CH(CH3)-CH3 -CH(OH)-CH2-CH3 -CH3 -CH(CH3)-CH3 -CH3 -CH2-CH3 -CH(CH3)-CH3 -CH2-CH3 -CH2-CH3 -CH(CH3)-CH3 -CH2-CH2-CH3 -CH2-CH3 -CH(CH3)-CH3 -CH(CH3)-CH3 -CH2-CH3 -CH(CH3)-CH3 -CH2-OH -CH2-CH3 -CH(CH3)-CH3 -CHZ-CHZ-OH -CH2-CH3 -CH(CH3)-CH3 -CH(OH)-CH3 -CH2-CH3 -CH(CH3)-CH3 -CH2-CH2-CH2-OH -CH2-CH3 -CH(CH3)-CH3 -CH2-CH(OH)-CH3 -CH2-CH3 -CH(CH3)-CH3 -CH(OH)-CHZ-CH3 -CH2-CH3 In the interests of easier synthesis, preferred compounds are those in which the substituents R' to R3 are identical, for example (CH3)3N~+~CH2-CN X-, (CH3CH2)3N~+~CH2-CN X-, (CH3CH2CH2)3N~+~CH2-CN X-, 5 (CH3CH(CH3))3N~+~CH2-CN X- or (HO-CH2-CH2)3N~+~CHz-CN X-. According to the invention, single- or multi-phase detergent tablets which contain a cationic nitrite corresponding to formula (la):

R5- i ~+~-(CH2)-CN X~-~ (la) Rs where R4, R5 and Rs independently of one another are selected from -CH3, -CH2-CH3, -CH2-CH2-CH3, -CH(CH3)-CH3, in addition to which R4 may even be -H, and X is an anion; preferably R5 = R6 = -CH3 and, more preferably, R4 = R5 = Rs = _CH3~
as the cationic nitrite of formula (I) are particularly preferred.
According to the invention, detergent tablets containing (CH3)3N~+~CH2-CN X, where X is an anion selected from the group consisting of chloride, bromide, iodide, hydrogen sulfate, methosulfate, p-toluene sulfonate (tosylate) or xylene sulfonate, as the cationic nitrite are particularly preferred.
The detergent tablets according to the invention contain an "activated bleaching" system, i.e. both bleaching agent and bleach activator, cationic nitrites being used in accordance with the invention as the bleach activator in order to obtain advantageous tablet properties. In addition to the cationic nitrites, the detergent tablets according to the invention may contain other bleach activators which are also described hereinafter. However, the detergent tablets according to the invention preferably contain the cationic nitrites corresponding to general formula (I) as sole or princpal bleach activator, i.e. at least 50% by weight of the total bleach activators present in the detergent tablets according to the invention is made up of cationic nitrites corresponding to formula (I). Bleach activators are added to bleach-containing detergents in order to obtain an improved bleaching effect at washing temperatures of 60°C or lower.
According to the invention, compounds which form aliphatic peroxocar-boxylic acids preferably containing 1 to 10 carbon atoms and more preferably 2 to 4 carbon atoms and/or optionally substituted perbenzoic acid under perhydrolysis conditions may be used as bleach activators in addition to the cationic nitrite. Suitable additional bleach activators are substances which contain O- and/or N-acyl groups with the number of carbon atoms indicated and/or optionally substituted benzoyl groups.
Preferred additional bleach activators are polyacylated alkylenediamines, more especially tetraacetyl ethylenediamine (TAED), acylated triazine derivatives, more particularly 1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine (DADHT), acylated glycol urils, more particularly tetraacetyl glycol uril (TAGU), N-acylimides, more particularly N-nonanoyl succinimide (NOSI), acylated phenol sulfonates, more particularly n-nonanoyl- or isononanoyl-oxybenzenesulfonate (n- or iso-NOBS), carboxylic anhydrides, more especially phthalic anhydride, acylated polyhydric alcohols, more especially triacetin, ethylene glycol diacetate and 2,5-diacetoxy-2,5-dihydrofuran.
In addition to or instead of the conventional bleach activators, so-called bleach catalysts may also be incorporated in the tablets in addition to the cationic nitrites of formula (I) in accordance with the present invention. Bleach catalysts are bleach-boosting transition metal salts or transition metal complexes such as, for example, Mn-, Fe-, Co-, Ru- or Mo-salen complexes or carbonyl complexes. Mn-, Fe-, Co-, Ru-, Mo-, Ti-, V-and Cu-complexes with N-containing tripod ligands and Co-, Fe-, Cu- and Ru-ammine complexes may also be used as bleach catalysts. Bleach-boosting active-substance combinations obtainable by thoroughly mixing a water-soluble salt of a divalent transition metal selected from cobalt, iron, copper and ruthenium and mixtures thereof, a water-soluble ammonium salt and optionally a peroxygen-based oxidizing agent and an inert carrier material may also be used as bleach catalysts in accordance with the present invention. If bleach catalysts are used for the purposes of the present invention, they are also governed by the particle size restrictions mentioned in the foregoing.
A particularly preferred additional bleach activator, i.e. a bleach activator used in addition to the cationic nitrite corresponding to formula (I), is N,N,N',N'-tetraacetyl ethylenediamine which is widely used in laundry/
dishwasher detergents. Accordingly, preferred detergent tablets are characterized in that they contain a cationic nitrite corresponding to formula (I) and tetraacetyl ethylenediamine (TAED) as bleach activators.
In "nitriloquat"/TAED combinations such as these, the ratio by weight of "nitriloquat" to TAED is preferably in the range from 1:2 to 10:1. In one particularly preferred embodiment, one third to two thirds of the total quantity of bleach activator in combinations such as these consists of cationic nitrite corresponding to formula (I).
The detergent tablets according to the invention contain the bleach activators) in quantities of 0.5 to 30% by weight, preferably in quantities of 1 to 20% by weight and more preferably in quantities of 2 to 15% by weight, based on the detergent tablet as a whole, reference being made here to the quantity data mentioned in the foregoing for the cationic nitrite.
The total quantities of bleach activators may vary according to the application envisaged for the tablets. Thus, in typical heavy-duty detergent tablets, bleach activator contents of 0.5 to 10% by weight, preferably 2 to 8% by weight and more preferably 4 to 7% by weight are normal whereas bleach tablets can have higher contents, for example from 5 to 30% by weight, preferably from 7.5 to 25% by weight and more preferably from 10 to 20% by weight. The expert is not restricted in his freedom of formulation and is able in this way to produce laundry detergent tablets, dishwasher tablets or bleach tablets with a stronger or weaker bleaching effect by varying the contents of bleach activator and bleaching agent.
The function of the bleach activators) in the detergent tablets according to the invention is to activate the bleaching agents) at relatively low washing temperatures and thus to provide for a high bleaching performance, even at low temperatures. Sodium perborate tetrahydrate and sodium perborate monohydrate are particularly important as bleaching agents. Other useful bleaching agents are, for example, sodium percarbonate, peroxypyrophosphates, citrate perhydrates and HZOZ-yielding peracidic salts or peracids, such as perbenzoates, peroxophthalates, diperazelaic acid, phthaloiminoperacid or diperdodecane dioic acid. Where bleaching agents are used, it is again possible to leave out surfactants and/or builders so that pure bleach tablets can be produced. If such bleach tablets are to be added to laundry, a combination of sodium percarbonate with sodium sesquicarbonate is preferably used irrespective of what other ingredients the tablets contain. If detergent or bleach tablets for dishwashing machines are being produced, bleaching agents from the group of organic bleaches may also be used. Typical organic bleaching agents are diacyl peroxides, such as dibenzoyl peroxide for example. Other typical organic bleaching agents are the peroxy acids, of which alkyl peroxy acids and aryl peroxy acids are particularly mentioned as examples. Preferred representatives are (a) peroxybenzoic acid and ring-substituted derivatives thereof, such as alkyl peroxybenzoic acids, but also peroxy-a-naphthoic acid and magnesium monoperphthalate, (b) aliphatic or substituted aliphatic peroxy acids, such as peroxylauric acid, peroxystearic acid, s-phthalimidoperoxycaproic acid [phthaloiminoperoxy-hexanoic acid (PAP)], o-carboxybenzamidoperoxycaproic acid, N-nonenylamidoperadipic acid and N-nonenylamidopersuccinates. and (c) aliphatic and araliphatic peroxydicarboxylic acids, such as 1,12-diperoxycarboxylic acid, 1,9-diperoxyazelaic acid, diperoxysebacic acid, diperoxybrassylic acid, diperoxyphthalic acids, 2-decyldiperoxybutane-1,4-dioic acid, N,N-terephthaloyl-di(6-aminopercaproic acid).
Other suitable bleaching agents in dishwasher tablets are chlorine-and bromine-releasing substances. Suitable chlorine- or bromine-releasing materials are, for example, heterocyclic N-bromamides and N-chloramides, for example trichloroisocyanuric acid, tribromoisocyanuric acid, dibromo-isocyanuric acid and/or dichloroisocyanuric acid (DICA) and/or salts thereof with cations, such as potassium and sodium. Hydantoin compounds, such as 1,3-dichloro-5,5-dimethyl hydantoin, are also suitable.
In laundry detergent tablets and also dishwasher tablets, sodium percarbonate is the preferred bleaching agent. "Sodium percarbonate" is a non-specific term used for sodium carbonate peroxohydrates which, strictly speaking, are not "percarbonates" (i.e. salts of percarbonic acid), but hydrogen peroxide adducts with sodium carbonate. The commercial material has the mean composition 2 Na2C03 ~ 3 H202 and, accordingly, is not a peroxycarbonate. Sodium percarbonate forms a white water-soluble powder with a density of 2.14 gcm3 which readily decomposes into sodium carbonate and bleaching or oxidizing oxygen.
Sodium carbonate peroxohydrate was obtained for the first time in 1899 by precipitation with ethanol from a solution of sodium carbonate in hydrogen peroxide, but was mistakenly regarded as peroxycarbonate. It was only in 1909 that the compound was recognised as a hydrogen peroxide addition compound. Nevertheless, the historical name "sodium percarbonate" has been adopted in practice.
On an industrial scale, sodium percarbonate is mainly produced by precipitation from aqueous solution (so-called wet process). In this pro-s cess, aqueous solutions of sodium carbonate and hydrogen peroxide are combined and the sodium percarbonate is precipitated by salting-out agents (mainly sodium chloride), crystallization aids (for example polyphos-phates, polyacrylates) and stabilizers (for example Mg2+ ions). The precipitated salt which still contains 5 to 12% by weight of mother liquor is 10 then removed by centrifuging and dried at 90°C in fluidized bed dryers.
The bulk density of the end product can vary between 800 and 1200 g/I
according to the production process. In general, the percarbonate is stabilized by an additional coating. Coating processes and materials are widely described in the patent literature. Basically, any commercially 15 available percarbonate types as marketed, for example, by Solvay Interox, Degussa, Kemira and Akzo may be used in accordance with the present invention.
The detergent tablets according to the invention may be single-phase tablets, i.e. may have been tabletted from a premix to form a homogeneous tablet. However, it is also possible and preferred in accordance with the invention to provide multiphase tablets where active substances can be divided up into spatially demarcated regions where this appears appropriate. According to the invention, preferred detergent tablets are two- or multi-phase detergent tablets where one phase contains the cationic nitrite of formula (I) in quantities of 2.5% by weight, preferably 5% by weight and more preferably 7.5% by weight, based on the weight of the phase, while the other phases) is/are preferably free from the cationic nitrite corresponding to formula (I) and, in particular, is/are free from all bleach activators.
By dividing up the total mass of a tablet into different phases, an increased content of certain ingredients, more particularly bleach activators, can be achieved in an individual phase providing the content of this ingredient in the other phases) is reduced accordingly without the total content of this active substance in the tablet varying. As can be seen from the above-mentioned quantities of bleach activators) in the tablet as a whole and from the above-mentioned quantities of bleach activators) in an individual phase, it is preferred in accordance with the invention to concentrate the bleach activators) in one phase of the tablet so that the corresponding phase has high bleach activator contents.
Multiphase tablets have the advantage over single-phase tablets that the pH criterion according to the invention can be satisfied more easily and universally in a phase than in the tablet as a whole. Due to the low pH
value which the phase is supposed to have after dissolution in water, the use of raw materials with a relatively highly alkaline pH in unlimited quantities is not possible and, according to the invention, should be avoided. Acidifying agents may have to be added to ensure that the cationic nitrites of formula (I) are present in the weakly alkaline to mildly acidic medium required in accordance with the invention. However, if indispensable alkaline raw materials are to be incorporated in the detergent, large quantities of acidifying agent would have to be used for a single-phase tablet. Through a phase split, the advantageous stabilization of the cationic nitrite and the use of alkaline raw materials are both possible by the presence of the alkaline raw materials, such as carbonates, phosphates, silicates, etc. in the phases) which is/are free from the cationic nitrite corresponding to formula (I).
According to the invention, the release of the activated bleaching system can also be delayed or accelerated so that further advantages in regard to cleaning performance are obtained. Delayed release can be obtained, for example, by coating particles or the entire phase while accelerated release can be obtained, for example, by adding disintegration aids to a phase. By applying such measures, it is possible, for example, to release the cationic nitrite corresponding to formula (I) at the beginning of the wash cycle, the wash liquor having a weakly alkaline or neutral to mildly acidic pH value if only the nitrite-containing phase dissolves. After dissolution of the other phase(s), the pH value may be drastically increased according to the composition of the phase(s). Conversely, delayed release of the cationic nitrite corresponding to formula (I) can also be achieved. If in this case the accelerated dissolution of the other phases) in relation to the nitrite-containing phase is intended to provide a high pH value, this can be compensated by acidifying agent in the nitrite-containing phase if the nitrite is to be released in the neutral to mildly acidic medium.
The division of the tablet into two or more phases may also be used to separate incompatible ingredients. According to the invention, two-phase or multiphase detergent tablets in which one phase contains the cationic nitrite corresponding to formula (I) while another phase contains all the bleaching agents) present in the tablets are preferred.
Where other ingredients are used besides bleaching agents and the cationic nitrite corresponding to formula (I), certain ingredients are preferably separated from one another. In the case of dishwasher tablets and laundry detergent tablets, two- or multi-phase detergent tablets which contain the cationic nitrite (I), bleaching agent and enzymes - the enzymes not being present in the same phase as the bleaching agent and the cationic nitrite - are preferred.
In addition, in the case of dishwasher tablets, two- or multi-phase detergent tablets which contain the cationic nitrite (I), bleaching agent and silver protector - the silver protector not being present in the same phase as the bleaching agent and the cationic nitrite - are preferred.
The ingredients mentioned are described in detail hereinafter.
Besides the ingredients mentioned above (bleach activator and bleaching agent), the detergent tablets according to the invention may contain other ingredients in quantities determined by the particular application envisaged for the tablets. Thus, substances from the groups of surfactants, builders and polymers are particularly suitable for use in the detergent tablets according to the invention. The expert will again have no difficulty in selecting the individual components and the quantities in which to use them. Thus, a heavy-duty detergent tablet will contain relatively large quantities of surfactants) whereas a bleach tablet may well contain no surfactant at all. The quantity of builders) used also varies according to the particular application envisaged.
The detergent tablets according to the invention may contain any of the builders normally used in detergents, i.e. in particular zeolites, silicates, carbonates, organic co-builders and - providing there are no ecological objections to their use - also phosphates.
Suitable crystalline layered sodium silicates correspond to the general formula NaMSixOZX+~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 layered silicates such as these are described, for example, in European patent application EP-A-0 164 514. Preferred crystalline layered silicates corresponding to the above formula are those in which M is sodium and x assumes the value 2 or 3. Both (i- and 8-sodium disilicates Na2Si205y HZO are particularly preferred, (i-sodium disilicate being obtainable, for example, by the process described in International patent application WO-A- 91/08171.
Other useful builders are amorphous sodium silicates with a modulus (Na20:Si02 ratio) of 1:2 to 1:3.3, preferably 1:2 to 1:2.8 and more preferably 1:2 to 1:2.6 which dissolve with delay and exhibit multiple wash cycle properties. The delay in dissolution in relation to conventional amorphous sodium silicates can have been obtained in various ways, for example by surface treatment, compounding, compacting or by overdrying.
In the context of the invention, the term "amorphous" is also understood to encompass "X-ray amorphous". In other words, the silicates do not produce any of the sharp X-ray reflexes typical of crystalline substances in X-ray diffraction experiments, but at best one or more maxima of the scattered X-radiation which have a width of several degrees of the diffraction angle. However, particularly good builder properties may even be achieved where the silicate particles produce crooked or even sharp diffraction maxima in electron diffraction experiments. This may be interpreted to mean that the products have microcrystalline regions between 10 and a few hundred nm in size, values of up to at most 50 nm and, more particularly, up to at most 20 nm being preferred. So-called X-ray amorphous silicates such as these, which also dissolve with delay in relation to conventional waterglasses, are described for example in German patent application DE-A-44 00 024. Compacted amorphous silicates, compounded amorphous silicates and overdried X-ray-amorphous silicates are particularly preferred.
The finely crystalline, synthetic zeolite containing bound water used in accordance with the invention is preferably zeolite A and/or zeolite P.
Zeolite MAP~ (Crosfield) is a particularly preferred P-type zeolite.
However, zeolite X and mixtures of A, X and/or P are also suitable.
According to the invention, it is also preferred to use, for example, a co-crystallizate of zeolite X and zeolite A (ca. 80% by weight zeolite X) which is marketed by CONDEA Augusta S.p.A. under the name of VEGOBOND
AX~ and which may be described by the following formula:
nNa20 ~ (1-n)K20 ~ AI203 ~ (2 - 2.5)Si02 ~ (3.5 - 5.5) H20.
The zeolite may be used both as a builder in a granular compound and as a kind of "powder" to be applied to the entire mixture to be tabletted, both routes normally being used to incorporate the zeolite in the premix.
Suitable zeolites have a mean particle size of less than 10 ~,m (volume distribution, as measured by the Coulter Counter Method) and contain preferably 18 to 22% by weight and more preferably 20 to 22% by weight of bound water.
The generally known phosphates may of course also be used as 5 builders providing their use should not be avoided on ecological grounds.
Among the large number of commercially available phosphates, alkali metal phosphates have the greatest importance in the detergent industry, pentasodium triphosphate and pentapotassium triphosphate (sodium and potassium tripolyphosphate) being particularly preferred.
10 "Alkali metal phosphates" is the collective term for the alkali metal (more particularly sodium and potassium) salts of the various phosphoric acids, including metaphosphoric acids (HP03)~ and orthophosphoric acid (H3P04) and representatives of higher molecular weight. The phosphates combine several advantages: they act as alkalinity sources, prevent lime 15 deposits on machine parts and lime incrustations in fabrics and, in addition, contribute towards the cleaning effect.
Sodium dihydrogen phosphate (NaH2P04) exists as the dehydrate (density 1.91 gcm-3, melting point 60°) and as the monohydrate (density 2.04 gcm 3). Both salts are white readily water-soluble powders which, on 20 heating, lose the water of crystallization and, at 200°, are converted into the weakly acidic diphosphate (disodium hydrogen diphosphate, Na2H2P20~) and, at higher temperatures, into sodium trimetaphosphate (Na3P309) and Maddrell's salt (see below). NaH2P04 shows an acidic reaction. It is formed by adjusting phosphoric acid with sodium hydroxide to a pH value of 4.5 and spraying the resulting "mash". Potassium dihydrogen phosphate (primary or monobasic potassium phosphate, potassium biphosphate, KDP), KH2P04, is a white salt with a density of 2.33 gcm-3, has a melting point of 253° [decomposition with formation of potassium polyphosphate (KP03)X] and is readily soluble in water.
Disodium hydrogen phosphate (secondary sodium phosphate), Na2HP04, is a colorless, readily water-soluble crystalline salt. It exists in water-free form and with 2 moles (density 2.066 gcm-3, water loss at 95°), 7 moles (density 1.68 gcm-3, melting point 48° with loss of 5 H20) and 12 moles of water (density 1.52 gcm-3, melting point 35° with loss of 5 H20), becomes water-free at 100° and, on fairly intensive heating, is converted into the diphosphate Na4P20~. Disodium hydrogen phosphate is prepared by neutralization of phosphoric acid with soda solution using phenol-phthalein as indicator. Dipotassium hydrogen phosphate (secondary or dibasic potassium phosphate), K2HP04, is an amorphous white salt which is readily soluble in water.
Trisodium phosphate, tertiary sodium phosphate, Na3P04, consists of colorless crystals which have a density of 1.62 gcm-3 and a melting point of 73-76° (decomposition) as the dodecahydrate, a melting point of 100° as the decahydrate (corresponding to 19-20% P205) and a density of 2.536 gcm-3 in water-free form (corresponding to 39-40% P205). Trisodium phosphate is readily soluble in water through an alkaline reaction and is prepared by concentrating a solution of exactly 1 mole of disodium phosphate and 1 mole of NaOH by evaporation. Tripotassium phosphate (tertiary or tribasic potassium phosphate), K3P04, is a white deliquescent granular powder with a density of 2.56 gcm-', has a melting of 1340°
and is readily soluble in water through an alkaline reaction. It is formed, for example, when Thomas slag is heated with coal and potassium sulfate.
Despite their higher price, the more readily soluble and therefore highly effective potassium phosphates are often preferred to corresponding sodium compounds in the detergent industry.
Tetrasodium diphosphate (sodium pyrophosphate), Na4P20~, exists in water-free form (density 2.534 gcm-3, melting point 988°, a figure of 880°
has also been mentioned) and as the decahydrate (density 1.815 - 1.836 gcm-3, melting point 94° with loss of water). Both substances are colorless crystals which dissolve in water through an alkaline reaction. Na4P20~ is formed when disodium phosphate is heated to >200° or by reacting phosphoric acid with soda in a stoichiometric ratio and spray-drying the solution. The decahydrate complexes heavy metal salts and hardness salts and, hence, reduces the hardness of water. Potassium diphosphate (potassium pyrophosphate), K4P20~, exists in the form of the trihydrate and is a colorless hygroscopic powder with a density of 2.33 gcm-3 which is soluble in water, the pH value of a 1 % solution at 25° being 10.4.
Relatively high molecular weight sodium and potassium phosphates are formed by condensation of NaHZP04 or KH2P04. They may be divided into cyclic types, namely the sodium and potassium metaphosphates, and chain types, the sodium and potassium polyphosphates. The chain types in particular are known by various different names: fused or calcined phosphates, Graham's salt, Kurrol's salt and Maddrell's salt. All higher sodium and potassium phosphates are known collectively as condensed phosphates.
The industrially important pentasodium triphosphate, Na5P30~o (sodium tripolyphosphate), is a non-hygroscopic white water-soluble salt which crystallizes without water or with 6 H20 and which has the general formula Na0-[P(O)(ONa)-O)"-Na where n = 3. Around 17 g of the salt free from water of crystallization dissolve in 100 g of water at room temperature, around 20 g at 60° and around 32 g at 100°. After heating of the solution for 2 hours to 100°, around 8% orthophosphate and 15% diphosphate are formed by hydrolysis. In the preparation of pentasodium triphosphate, phosphoric acid is reacted with soda solution or sodium hydroxide in a stoichiometric ratio and the solution is spray-dried. Similarly to Graham's salt and sodium diphosphate, pentasodium triphosphate dissolves many insoluble metal compounds (including lime soaps, etc.). Pentapotassium triphosphate, K5P30~o (potassium tripolyphosphate), is marketed for example in the form of a 50% by weight solution (> 23% P205, 25% K20).
The potassium polyphosphates are widely used in the detergent industry.

Sodium potassium tripolyphosphates, which may also be used in accordance with the invention, also exist. They are formed for example when sodium trimetaphosphate is hydrolyzed with KOH:
(NaP03)3 + 2 KOH -~ Na3K2P30~o + H20 According to the invention, they may be used in exactly the same way as sodium tripolyphosphate, potassium tripolyphosphate or mixtures thereof. Mixtures of sodium tripolyphosphate and sodium potassium tripolyphosphate or mixtures of potassium tripolyphosphate and sodium potassium tripolyphosphate or mixtures of sodium tripolyphosphate and potassium tripolyphosphate and sodium potassium tripolyphosphate may also be used in accordance with the invention.
Organic cobuilders suitable for use in the detergent tablets according to the invention are, in particular, polycarboxylates/polycarboxylic acids, polymeric polycarboxylates, aspartic acid, polyacetals, dextrins, other organic cobuilders (see below) and phosphonates. These classes of substances are described in the following.
Useful organic builders are, for example, the polycarboxylic acids usable, for example, in the form of their sodium salts, polycarboxylic acids in this context being understood to be carboxylic acids which bear more than one acid function. Examples of such carboxylic acids are citric acid, adipic acid, succinic acid, glutaric acid, malic acid, tartaric acid, malefic acid, fumaric acid, sugar acids, aminocarboxylic acids, nitrilotriacetic acid (NTA), providing their use is not ecologically unsafe, and mixtures thereof.
Preferred salts are the salts of the polycarboxylic acids, such as citric acid, adipic acid, succinic acid, glutaric acid, tartaric acid, sugar acids and mixtures thereof.
The acids per se may also be used. Besides their builder effect, the acids also typically have the property of an acidifying component and, hence, also serve to establish a relatively low and mild pH value in detergents. Citric acid, succinic acid, glutaric acid, adipic acid, gluconic acid and mixtures thereof are particularly mentioned in this regard.
Other suitable builders are polymeric polycarboxylates such as, for example, the alkali metal salts of polyacrylic or polymethacrylic acid, for example those with a relative molecular weight of 500 to 70,000 g/mole.
The molecular weights mentioned in this specification for polymeric polycarboxylates are weight-average molecular weights MW of the particular acid form which, basically, were determined by gel permeation chromatography (GPC) using a UV detector. The measurement was carried out against an external polyacrylic acid standard which provides realistic molecular weight values by virtue of its structural similarity to the polymers investigated. These values differ distinctly from the molecular weights measured against polystyrene sulfonic acids as standard. The molecular weights measured against polystyrene sulfonic acids are generally higher than the molecular weights mentioned in this specification.
Particularly suitable polymers are polyacrylates which preferably have a molecular weight of 2,000 to 20,000 g/mole. By virtue of their superior solubility, preferred representatives of this group are the short-chain polyacrylates which have molecular weights of 2,000 to 10,000 glmole and, more particularly, 3,000 to 5,000 g/mole.
Also suitable are copolymeric polycarboxylates, particularly those of acrylic acid with methacrylic acid and those of acrylic acid or methacrylic acid with malefic acid. Acrylic 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 g/mole, preferably in the range from 20,000 to 50,000 g/mole and more preferably in the range from 30,000 to 40,000 g/mole.
The (co)polymeric polycarboxylates may be used either in powder form or in the form of an aqueous solution. The content of (co)polymeric polycarboxylates in the detergent is preferably from 0.5 to 20% by weight and more preferably from 3 to 10% by weight.
In order to improve solubility in water, the polymers may also contain 5 allyl sulfonic acids, such as allyloxybenzene sulfonic acid and methallyl sulfonic acid, as monomer.
Other particularly preferred polymers are biodegradable polymers of more than two different monomer units, for example those which contain salts of acrylic acid and malefic acid and vinyl alcohol or vinyl alcohol 10 derivatives as monomers or those which contain salts of acrylic acid and 2-alkylallyl sulfonic acid and sugar derivatives as monomers.
Other preferred copolymers are those which are described in German patent applications DE-A-43 03 320 and DE-A-44 17 734 and which preferably contain acrolein and acrylic acid/acrylic acid salts or 15 acrolein and vinyl acetate as monomers.
Other preferred builders are polymeric aminodicarboxylic acids, salts or precursors thereof. Particular preference is attributed to polyaspartic acids or salts and derivatives thereof which, according to German patent application DE-A-195 40 086, are also said to have a bleach-stabilizing 20 effect in addition to their co-builder properties.
Other suitable builders are polyacetals which may be obtained by reaction of dialdehydes with polyol carboxylic acids containing 5 to 7 carbon atoms and at least three hydroxyl groups. Preferred polyacetals are obtained from dialdehydes, such as glyoxal, glutaraldehyde, terephthal-25 aldehyde and mixtures thereof and from polyol carboxylic acids, such as gluconic acid and/or glucoheptonic acid.
Other suitable organic builders are dextrins, for example oligomers or polymers of carbohydrates which may be obtained by partial hydrolysis of starches. The hydrolysis may be carried out by standard methods, for example acid- or enzyme-catalyzed methods. The end products are preferably hydrolysis products with average molecular weights of 400 to 500,000 g/mol. A polysaccharide with a dextrose equivalent (DE) of 0.5 to 40 and, more particularly, 2 to 30 is preferred, the DE being an accepted measure of the reducing effect of a polysaccharide by comparison with dextrose which has a DE of 100. Both maltodextrins with a DE of 3 to 20 and dry glucose sirups with a DE of 20 to 37 and also so-called yellow dextrins and white dextrins with relatively high molecular weights of 2,000 to 30,000 g/mole may be used.
The oxidized derivatives of such dextrins are their reaction products with oxidizing agents which are capable of oxidizing at least one alcohol function of the saccharide ring to the carboxylic acid function. 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-0 542 496 and from International patent applications WO 92/18542, WO 93/08251, WO 93/16110, WO 94/28030, WO 95/07303, 9 and WO 95/20608. An oxidized oligosaccharide corresponding 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 preferred in this connection. The quantities used in zeolite-containing and/or silicate-containing formulations are from 3 to 15% by weight.
Other useful organic co-builders are, for example, acetylated hydroxycarboxylic acids and salts thereof which may optionally be present in lactone form and which contain at least 4 carbon atoms, at least one hydroxy group and at most two acid groups. Co-builders such as these are described, for example, in International patent application WO-A-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 importance as a co-builder. It is preferably used in the form of the sodium salt, the disodium salt showing a neutral reaction and the tetrasodium salt an alkaline reaction (pH 9).
Preferred aminoalkane phosphonates are ethylenediamine tetramethylene phosphonate (EDTMP), diethylenetriamine pentamethylenephosphonate (DTPMP) and higher homologs thereof. They are preferably used in the form of the neutrally reacting sodium salts, for example as the hexasodium salt of EDTMP or as the hepta- and octasodium salts of DTPMP. Of the phosphonates, HEDP is preferably used as a builder. In addition, the aminoalkane phosphonates have a pronounced heavy metal binding capacity. Accordingly, it can be of advantage, particularly where the detergents also contain bleach, to use aminoalkane phosphonates, more particularly DTPMP, or mixtures of the phosphonates mentioned.
In addition, any compounds capable of forming complexes with alkaline earth metal ions may be used as co-builders.
The quantity of builder used is normally between 10 and 70% by weight, preferably between 15 and 60% by weight and more preferably between 20 and 50% by weight. The quantity of builder used is again dependent upon the particular application envisaged, so that bleach tablets can contain larger quantities of builders (for example between 20 and 70%
by weight, preferably between 25 and 65% by weight and more preferably between 30 and 55% by weight) than, for example, laundry detergent tablets (normally 10 to 50% by weight, preferably 12.5 to 45% by weight and more preferably 17.5 to 37.5% by weight).
Preferred detergent tablets additionally contain one or more surfactant(s). Anionic, nonionic, cationic and/or amphoteric surfactants or mixtures thereof may be used in the detergent tablets according to the invention. Mixtures of anionic and nonionic surfactants are preferred from the performance point of view. The total surfactant content of the tablets is from 5 to 60% by weight, based on the weight of the tablet, surfactant contents above 15% by weight being preferred in the case of laundry detergent tablets and dishwasher tablets normally containing less than 3%
by weight of surfactant.
The anionic surfactants used 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_~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 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.
Other suitable anionic surfactants are sulfonated fatty acid glycerol esters, i.e. the monoesters, diesters and triesters and mixtures thereof which are obtained where production is carried out by esterification by 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 satturated C6_22 fatty acids, for example caproic acid, caprylic acid, capric acid, myristic acid, lauric acid, palmitic acid, stearic acid or behenic acid.
Preferred alk(en)yl sulfates are the alkali metal salts and, in particular, the sodium salts of the sulfuric acid semiesters of C~2_~$ fatty alcohols, for example coconut alcohol, tallow alcohol, lauryl, myristyl, cetyl or stearyl alcohol, or C~o_2o oxoalcohols and the corresponding semiesters of secondary alcohols with the same chain length. Other preferred alk(en)yl sulfates are those with the chain length mentioned which contain a synthetic, linear alkyl chain based on a petrochemical and which are similar in their degradation behavior to the corresponding compounds based on oleochemical raw materials. C~2_~6 alkyl sulfates and C~2_~5 alkyl sulfates and also C~4_~5 alkyl sulfates alkyl sulfates are particularly preferred from the washing performance point of view. 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 C9_> > alcohols containing on average 3.5 moles of ethylene oxide (EO) or C~2_~a fatty alcohols containing 1 to 4 EO, are also suitable. In view of their high foaming capacity, they are normally used in only relatively small quantities, for example in quantities of 1 to 5% by weight, in dishwashing detergents.
Other suitable anionic surfactants are the salts of alkyl sulfosuccinic acid which are also known as sulfosuccinates or as sulfosuccinic acid esters and which represent monoesters and/or diesters of sulfosuccinic acid with alcohols, preferably fatty alcohols and, more particularly, ethoxylated fatty alcohols. Preferred sulfosuccinates contain C8_~$ fatty alcohol molecules or mixtures thereof. Particularly preferred sulfosuccinates contain a fatty alcohol molecule derived from ethoxylated fatty alcohols which, considered in isolation, represent nonionic surfactants (for a description, see below). Of these sulfosuccinates, those of which the fatty alcohol molecules are derived from narrow-range ethoxylated fatty alcohols are particularly preferred. Alk(en)yl succinic acid preferably containing 8 to 18 carbon atoms in the alk(en)yl chain or salts thereof may also be used.

Other suitable anionic surfactants are, in particular, soaps. Suitable soaps are, in particular, saturated fatty acid soaps, such as the salts of lauric acid, myristic acid, palmitic acid, stearic acid, hydrogenated erucic acid and behenic acid, and soap mixtures derived in particular from natural 5 fatty acids, for example coconut, palm kernel or tallow acids.
The anionic surfactants, including the soaps, may be present in the form of their sodium, potassium or ammonium salts and as soluble salts of organic bases, such as mono-, di- or triethanolamine. The anionic surfactants are preferably present in the form of their sodium or potassium 10 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 radical may be linear or, preferably, 15 methyl-branched in the 2-position or may contain linear and methyl-branched radicals in the form of the mixtures typically present in oxoalcohol radicals. However, alcohol ethoxylates containing linear radicals of alcohols of native origin with 12 to 18 carbon atoms, for example coconut oil, palm oil, tallow or oleyl alcohol, and on average 2 to 8 EO per mole of 20 alcohol are particularly preferred. Preferred ethoxylated alcohols include, for example, C~2-~a alcohols containing 3 EO or 4 EO, C9_» alcohol containing 7 EO, C~3-~5 alcohols containing 3 EO, 5 EO, 7 EO or 8 EO, C~2_~$ alcohols containing 3 EO, 5 EO or 7 EO and mixtures thereof, such as mixtures of C~2_~4 alcohol containing 3 EO and C~2_~$ alcohol containing 25 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 30 including tallow fatty alcohol containing 14 EO, 25 EO, 30 EO or 40 EO.

Suitable other nonionic surfactants are alkyl glycosides with the general formula RO(G)X where R is a primary, linear or methyl-branched, more particularly 2-methyl-branched, aliphatic radical containing 8 to 22 and preferably 12 to 18 carbon atoms and G stands for a glycose unit containing 5 or 6 carbon atoms, preferably glucose. The degree of oligomerization x, which indicates the distribution of monoglycosides and oligoglycosides, is a number of 1 to 10 and preferably 1.2 to 1.4.
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-90/13533.
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 (II):
R~
R-CO-N-[Z] ( I I ) in which RCO is an aliphatic acyl group containing 6 to 22 carbon atoms, R' is hydrogen, an alkyl or hydroxyalkyl group containing 1 to 4 carbon atoms and [Z] is a linear or branched polyhydroxyalkyl group containing 3 to 10 carbon atoms and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid amides are known substances which may normally be obtained by reductive amination of a reducing sugar with ammonia, an alkylamine or an alkanolamine and subsequent acylation with a fatty acid, a fatty acid alkyl ester or a fatty acid chloride.
The group of polyhydroxyfatty acid amides also includes compounds corresponding to formula (III):
R'-O-R2 R-CO-N-[Z] (III) in which R is a linear or branched alkyl or alkenyl group containing 7 to 12 carbon atoms, R' is a linear, branched or cyclic alkyl group or an aryl group containing 2 to 8 carbon atoms and R2 is a linear, branched or cyclic alkyl group or an aryl group or an oxyalkyl group containing 1 to 8 carbon atoms, C~~ alkyl or phenyl groups being preferred, and [Z] is a linear polyhydroxy-alkyl group, of which the alkyl chain is substituted by at least two hydroxyl groups, or alkoxylated, preferably ethoxylated or propoxylated, derivatives of that group.
[Z] is preferably obtained by reductive amination of a reduced sugar, for example glucose, fructose, maltose, lactose, galactose, mannose or xylose. The N-alkoxy- or N-aryloxy-substituted compounds may then be converted into the required polyhydroxyfatty acid amides by reaction with fatty acid methyl esters in the presence of an alkoxide as catalyst, for example in accordance with the teaching of International patent application WO-A-95107331.
According to the invention, preferred detergent tablets contain anionic and/or nonionic surfactants) and have total surfactant contents above 2.5% by weight, preferably above 5% by weight and more preferably above 10% by weight, based on the weight of the tablet. Performance-related advantages can arise out of certain quantity ratios in which the individual classes of surfactants are used.

For example, particularly preferred detergent tablets are charac-terized in that the ratio of anionic surfactants) to nonionic surfactants) is from 10:1 to 1:10, preferably from 7.5:1 to 1:5 and more preferably from 5:1 to 1:2.
It can be of advantage from the performance point of view if certain classes of surfactants are missing from certain phases of the detergent tablets or from the entire tablet, i.e. from every phase. In another important embodiment of the present invention, therefore, at least one phase of the tablets is free from nonionic surfactants.
Conversely, a positive effect can also be obtained through the presence of certain surfactants in individual phases or in the tablet as a whole, i.e. in every phase. Introducing the alkyl polyglycosides described above has proved to be of particular advantage, so that detergent tablets in which at least one phase of the tablet contains alkyl polyglycosides are preferred.
As with the nonionic surfactants, the omission of anionic surfactants from individual phases or from all phases can result in detergent tablets which are more suitable for certain applications. Accordingly, detergent tablets where at least one phase of the tablet is free from anionic surfactants are also possible in accordance with the present invention.
In order to facilitate the disintegration of heavily compacted tablets, disintegration aids, so-called tablet disintegrators, may be incorporated in them to shorten their disintegration times. According to Rompp (9th Edition, Vol. 6, page 4440) and Voigt "Lehrbuch der pharmazeutischen Technologie" (6th Edition, 1987, pages 182-184), tablet disintegrators or disintegration accelerators are auxiliaries which provide for the rapid disintegration of tablets in water or gastric juices and the release of the pharmaceuticals in an absorbable form.
These substances, which are also known as "disintegrators" by virtue of their effect, are capable of undergoing an increase in volume on contact with water so that, on the one hand, their own volume is increased (swelling) and, on the other hand, a pressure can be generated through the release of gases which causes the tablet to disintegrate into relatively small particles. Well-known disintegrators are, for example, carbonate/citric acid systems, although other organic acids may also be used. Swelling dis-integration aids are, for example, synthetic polymers, such as polyvinyl pyrrolidone (PVP), or natural polymers and modified natural substances, such as cellulose and starch and derivatives thereof, alginates or casein derivatives.
Preferred detergent tablets contain 0.5 to 10% by weight, preferably 3 to 7% by weight and more preferably 4 to 6% by weight of one or more disintegration aids, based on the weight of the tablet.
According to the invention, preferred disintegrators are cellulose-based disintegrators, so that preferred detergent tablets contain a cellulose-based disintegrator in quantities of 0.5 to 10% by weight, preferably 3 to 7% by weight and more preferably 4 to 6% by weight. Pure cellulose has the formal empirical composition (C6H~pO5)n and, formally, is a ~3-1,4-polyacetal of cellobiose which, in turn, is made up of two molecules of glucose. Suitable celluloses consist of ca. 500 to 5000 glucose units and, accordingly, have average molecular weights of 50,000 to 500,000.
According to the invention, cellulose derivatives obtainable from cellulose by polymer-analog reactions may also be used as cellulose-based disintegrators. These chemically modified celluloses include, for example, products of esterification or etherification reactions in which hydroxy hydrogen atoms have been substituted. However, celluloses in which the hydroxy groups have been replaced by functional groups that are not attached by an oxygen atom may also be used as cellulose derivatives.
The group of cellulose derivatives includes, for example, alkali metal celluloses, carboxymethyl cellulose (CMC), cellulose esters and ethers and aminocelluloses. The cellulose derivatives mentioned are preferably not used on their own, but rather in the form of a mixture with cellulose as 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 5 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 10 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-A-98/40463 (Henkel). Further particulars of the production of granulated, compacted or co-granulated 15 cellulose disintegrators can also be found in these patent applications.
The particle sizes of such disintegration aids is mostly above 200 Nm, at least 90% by weight of the particles being between 300 and 1600 Nm in size and, more particularly, between 400 and 1200 Nm in size. According to the invention, the above-described relatively coarse-particle cellulose-based 20 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 25 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 30 celluloses which have primary particle sizes of ca. 5 Nm and which can be compacted, for example, to granules with a mean particle size of 200 Nm.
According to the present invention, single- or multi-phase detergent tablets additionally containing a disintegration aid, preferably a cellulose-based disintegration aid, preferably in granulated, cogranulated or compacted form, in quantities of 0.5 to 10% by weight, preferably 3 to 7%
by weight and more preferably 4 to 6% by weight, based on the weight of the tablet, are preferred.
Besides the ingredients mentioned (bleach activator, bleaching agent, builder, surfactant and disintegration aid), the detergent tablets according to the invention may also contain one or more substances from the group of builders, enzymes, pH regulators, perfumes, perfume carriers, fluorescers, dyes, foam inhibitors, silicone oils, redeposition inhibitors, optical brighteners, discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors. These substances are described in the following.
Suitable enzymes are, in particular, those from the classes of hydrolases, such as proteases, esterases, lipases or lipolytic enzymes, amylases, cellulases or other glycosyl hydrolases and mixtures thereof. All these hydrolases contribute to the removal of stains, such as protein-containing, fat-containing or starch-containing stains, and discoloration in the washing process. Cellulases and other glycosyl hydrolases can contribute towards color retention and towards increasing fabric softness by removing pilling and microfibrils. Oxidoreductases may also be used for bleaching and for inhibiting dye transfer. Enzymes obtained from bacterial strains or fungi, such as Bacillus subtilis, Bacillus licheniformis, Streptomyces griseus, Coprinus cinereus and Humicola insolens and from genetically modified variants are particularly suitable. Proteases of the subtilisin type are preferably used, proteases obtained from Bacillus lentus being particularly preferred. Of particular interest in this regard are enzyme mixtures, for example of protease and amylase or protease and lipase or lipolytic enzymes or protease and cellulase or of cellulase and lipase or lipolytic enzymes or of protease, amylase and lipase or lipolytic enzymes or protease, lipase or lipolytic enzymes and cellulase, but especially protease-and/or lipase-containing mixtures or mixtures with lipolytic enzymes.
Examples of such lipolytic enzymes are the known cutinases. Peroxidases or oxidases have also been successfully used in some cases. Suitable amylases include in particular a-amylases, isoamylases, pullanases and pectinases. Preferred cellulases are cellobiohydrolases, endoglucanases and ~i-glucosidases, which are also known as cellobiases, and mixtures thereof. Since the various cellulase types differ in their CMCase and avicelase activities, the desired activities can be established by mixing the cellulases in the appropriate ratios.
The enzymes may be adsorbed to supports and/or encapsulated in shell-forming substances to protect them against premature decomposition.
The percentage content of the enzymes, enzyme mixtures or enzyme granules may be, for example, from about 0.1 to 5% by weight and is preferably from 0.5 to about 4.5% by weight.
The choice of the particular enzymes is also dependent on the application envisaged for the detergent tablets according to the invention.
Particularly suitable enzymes for dishwasher tablets are those from the classes of hydrolases, such as proteases, esterases, lipases or lipolytic enzymes, amylases, glycosyl hydrolases and mixtures thereof. All these hydrolases contribute to the removal of stains, such as protein-containing, fat-containing or starch-containing stains. Oxidoreductases may also be used for bleaching. Enzymes obtained from bacterial strains or fungi, such as Bacillus subtilis, Bacillus licheniformis, Streptomyces griseus, Coprinus cinereus and Humicola insolens and from genetically modified variants are particularly suitable. Proteases of the subtilisin type are preferably used, proteases obtained from Bacillus lentus being particularly preferred. Of particular interest in this regard are enzyme mixtures, for example of protease and amylase or protease and lipase or lipolytic enzymes or of protease, amylase and lipase or lipolytic enzymes or protease, lipase or lipolytic enzymes, but especially protease- and/or lipase-containing mixtures or mixtures with lipolytic enzymes. Examples of such lipolytic enzymes are the known cutinases. Peroxidases or oxidases have also proved suitable in some cases. Suitable amylases include in particular a-amylases, isoamylases, pullanases and pectinases.
In the case of dishwasher tablets also, 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 may again be, for example, from about 0.1 to 5% by weight and is preferably from 0.5 to about 4.5% by weight.
Dishwasher tablets according to the invention may contain corrosion inhibitors to protect the tableware or the machine itself, silver protectors being particularly important for dishwashing machines. Known corrosion inhibitors may be used. Above all, silver protectors selected from the group of triazoles, benzotriazoles, bisbenzotriazoles, aminotriazoles, alkylaminotriazoles and the transition metal salts or complexes may generally be used. Benzotriazole and/or alkylaminotriazole is/are particularly preferred. In addition, dishwashing formulations often contain corrosion inhibitors containing active chlorine which are capable of distinctly reducing the corrosion of silver surfaces. Chlorine-free dishwashing detergents contain in particular oxygen- and nitrogen-containing organic redox-active compounds, such as dihydric and trihydric phenols, for example hydroquinone, pyrocatechol, hydroxyhydroquinone, gallic acid, phloroglucinol, pyrogallol and derivatives of these compounds.
Salt-like and complex-like inorganic compounds, such as salts of the metals Mn, Ti, Zr, Hf, V, Co and Ce are also frequently used. Of these, the transition metal salts selected from the group of manganese and/or cobalt salts and/or complexes are preferred, cobalt(ammine) complexes, cobalt(acetate) complexes, cobalt(carbonyl) complexes, chlorides of cobalt or manganese and manganese sulfate being particularly preferred. Zinc compounds may also be used to prevent corrosion of tableware.
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 compo-nents include, for example, nonionic cellulose ethers, such as methyl cellulose and methyl hydroxypropyl cellulose containing 15 to 30% by weight of methoxyl groups and 1 to 15% by weight of hydroxypropoxyl groups, based on the nonionic cellulose ether, and the polymers of phthalic acid and/or terephthalic acid known from the prior art or derivatives thereof, more particularly polymers of ethylene terephthalates and/or polyethylene glycol terephthalates or anionically and/or nonionically modified derivatives thereof. Of these, the sulfonated derivatives of phthalic acid and terephthalic acid polymers are particularly preferred.
The tablets may contain derivatives of diaminostilbenedisulfonic acid or alkali metal salts thereof as optical brighteners. Suitable optical brighteners are, for example, salts of 4,4'-bis-(2-anilino-4-morpholino-1,3,5-triazinyl-6-amino)-stilbene-2,2'-disulfonic acid or compounds of similar composition which contain a diethanolamino group, a methylamino group, an anilino group or a 2-methoxyethylamino group instead of the morpholino group. Brighteners of the substituted diphenyl styryl type, for example alkali metal salts of 4,4'-bis-(2-sulfostyryl)-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 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 5 individual perfume compounds, for example synthetic products of the ester, ether, aldehyde, ketone, alcohol and hydrocarbon type. Perfume com-pounds of the ester type are, for example, benzyl acetate, phenoxyethyl isobutyrate, p-tert.butyl cyclohexyl acetate, linalyl acetate, dimethyl benzyl carbinyl acetate, phenyl ethyl acetate, linalyl benzoate, benzyl formate, 10 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, citronellyloxy-acetaldehyde, cyclamen aldehyde, hydroxycitronellal, lilial and bourgeonal;
15 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 20- note are preferably used. Perfume oils such as these may also contain natural perfume mixtures obtainable from vegetable sources, for example pine, citrus, jasmine, patchouli, rose or ylang-ylang oil. Also suitable are clary oil, camomile oil, clove oil, melissa oil, mint oil, cinnamon leaf oil, lime blossom oil, juniper berry oil, vetiver oil, olibanum oil, galbanum oil and 25 labdanum oil and orange blossom oil, neroli oil, orange peel oil and sandalwood oil.
The detergent tablets according to the invention normally contain less than 0.01 % by weight of dyes whereas perfumes/fragrances can make up as much as 2% by weight of the formulation as a whole.
30 The perfumes may be directly incorporated in the detergents according to the invention, although it can also be of advantage to apply the perfumes to supports which strengthen the adherence of the perfume to the washing and which provide the textiles with a long-lasting fragrance through a slower release of the perfume. Suitable support materials are, for example, cyclodextrins, the cyclodextrin/perfume complexes optionally being coated with other auxiliaries.
In order to improve their aesthetic impression, the detergents according to the invention may be colored with suitable dyes. Preferred dyes, which are not difficult for the expert to choose, have high stability in storage, are not affected by the other ingredients of the detergents or by light and do not have any pronounced substantivity for textile fibers so as not to color them.
Detergent tablets are produced by applying pressure to a mixture to be tabletted which is accommodated in the cavity of a press. In the most simple form of tabletting, the mixture to be tabletted is tabletted directly, i.e.
without preliminary granulation. The advantages of this so-called direct tabletting lie in its simple and inexpensive application because no other process steps and hence no other items of equipment are required.
However, these advantages are often offset by disadvantages. Thus, a powder mixture which is to be directly tabletted must show adequate plasticity and good flow properties and should not have any tendency to separate during storage, transportation and filling of the die. With many mixtures, these three requirements are very difficult to satisfy with the result that direct tabletting is often not applied, particularly in the production of detergent tablets. Accordingly, the normal method of producing detergent tablets starts out from powder-form components ("primary particles") which are agglomerated or granulated by suitable methods to form secondary particles with a larger particle diameter. These granules or mixtures of different granules are then mixed with individual powder-form additives and tabletted.

The present invention also relates to a process for the production of single- or multi-phase detergent tablets by tabletting one or more particulate premixes in known manner, characterized in that the premix for the entire tablet or for at least one of the phases contains a cationic nitrite corresponding to formula (I):
R' R2-N~+~-(CH2)-CN X~-~ (I) in which R' represents -H, -CH3, a C2_24 alkyl or alkenyl group, a substituted C2_24 alkyl or alkenyl group with at least one substituent from the group consisting of -CI, -Br, -OH, -NHZ, -CN, an alkyl or alkenyl aryl group containing a C~_24 alkyl group or a substituted alkyl or alkenyl aryl group containing a C~_24 alkyl group and at least one other substituent at the aromatic ring, RZ ad R3 independently of one another are selected from -CH2-CN, -CH3, -CH2-CH3, -CHZ-CH2-CH3, -CH(CH3)-CH3, -CHZ-OH, -CH2-CH2-OH, -CH(OH)-CH3, -CH2-CHZ-CH2-OH, -CHZ-CH(OH)-CH3, -CH(OH)-CH2-CH3, -(CH2CH2-O)nH where n = 1, 2, 3, 4, 5 or 6 and X is an anion, the pH value of a 1 % by weight aqueous solution of the particular premix being below 10.
In the production of single-phase detergent tablets, the entire premix has to satisfy the pH criterion mentioned. In the production of multiphase tablets by pressing various premixes onto or into one another, only the premix containing the cationic nitrite of formula (I) need have a pH below 7 in the form of a 1 % by weight aqueous solution.
Preferred embodiments of the process according to the invention should be regarded similarly to the detergent tablets according to the invention. Thus, according to the invention, processes in which the pH
value of a 1 % by weight aqueous solution of the premix for the entire tablet or for the phase containing the cationic nitrite (I) is below 9, preferably below 8, more preferably below 7 and most preferably below 6, are preferred.
In the process according to the invention also, the pH is preferably within a relatively narrow range so that processes where the pH of a 1 % by weight aqueous solution of the premix for the entire tablet or for the phase containing the cationic nitrite (I) is below 6.5, preferably below 6, more preferably below 5.5 and most preferably below 5 are preferred.
So far as other preferred embodiments of the process according to the invention are concerned, reference is made to the foregoing observations on the detergent tablets according to the invention. Thus, cationic nitrite contents in the premix of 0.25 to 15% by weight and, more particularly, 0.5 to 10% by weight, based on the premix, are preferred.
The foregoing observations on the particle sizes of the cationic nitrite again apply. According to the invention, preferred processes are also characterized in that at least 90% by weight of the particles of the cationic nitrite corresponding to formula (I) have a particle size above 0.2 mm, at least 40% by weight, preferably at least 50% by weight and more preferably at least 60% by weight of the particles of the cationic nitrite corresponding to formula (I) having a particle size above 0.4 mm. Particularly preferred variants of the process are characterized in that the cationic nitrite corresponding to formula (I) has a mean particle size above 400 Nm, preferably above 500 pm, more preferably above 600 Nm and, in one particularly preferred embodiment, above 700 Nm.
The foregoing observations also apply in regard to the cationic nitrites preferably used. In particularly preferred processes, the premix contains (CH3)3N~+~CH2-CN X, where X is an anion selected from the group consisting of chloride, bromide, iodide, hydrogen sulfate, methosulfate, p-toluene sulfonate (tosylate) or xylene sulfonate, as the cationic nitrite.
According to the invention. preferred detergent tablets are produced by tabletting a particulate premix of surfactant-containing granules of at least one type and at least one powder-form component subsequently added. The surfactant-containing granules may be produced by conventional industrial granulation processes, such as compacting, extrusion, mixer granulation, pelleting or fluidized bed granulation. It is of advantage so far as the subsequent detergent tablets are concerned if the premix to be tabletted has a bulk density approaching that of typical compact detergents. In one particularly preferred embodiment, the premix to be tabletted has a bulk density of at least 500 g/I, preferably of at least 600 g/I and more preferably of at least 700 g/I.
In preferred variants of the process, the surfactant-containing granules also satisfy certain particle size criteria. Thus, preferred processes according to the invention are characterized in that the surfactant-containing granules have particle sizes of 100 to 2000 Nm, preferably 200 to 1800 Nm, more preferably 400 to 1600 Nm and most preferably 600 to 1400 Nm.
Besides the active substances (anionic and/or nonionic and/or cationic and/or amphoteric surfactants), the surfactant granules preferably contain carrier materials which, in one particularly preferred embodiment, emanate from the group of builders. Accordingly, particularly advantageous processes are characterized in that the surfactant-containing granules contain anionic and/or nonionic surfactants and builders and have total surfactant contents of at least 10% by weight, preferably at least 20%
by weight and more preferably at least 25% by weight.
Before the particulate premix is compressed to form detergent tablets, it may be "powdered" with fine-particle surface treatment materials.
This can be of advantage to the quality and physical properties of both the premix (storage, tabletting) and the final detergent tablets. Fine-particle powdering materials have been known for some time in the art, zeolites, silicates and other inorganic salts generally being used. However, the premix is preferably "powdered" with fine-particle zeolite, zeolites of the faujasite type being preferred. In the context of the 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 5 W. Breck: "Zeolite Molecular Sieves" John Wiley & Sons, New York/London/Sydney/Toronto, 1974, page 92). Besides zeolite X, there-fore, zeolite Y and faujasite and mixtures of these compounds may also be used, pure zeolite X being preferred.
Mixtures or co-crystallizates of faujasite zeolites with other zeolites 10 which need not necessarily belong to zeolite structure group 4 may also be used as powdering materials, in which case at least 50% by weight of the powdering material advantageously consists of a faujasite zeolite.
According to the invention, preferred detergent tablets consist of a particulate premix containing granular components and powder-form 15 substances subsequently added, the - or one of the - powder-form components subsequently incorporated being a faujasite zeolite with particle sizes below 100 Nm, preferably below 10 Nm and more preferably below 5 Nm and making up at least 0.2% by weight, preferably at least 0.5% by weight and more preferably more than 1 % by weight of the premix 20 to be tabletted.
Besides the components mentioned (surfactant, builder and disintegration aid), the premixes to be tabletted may additionally contain one or more substances from the group of bleaching agents, bleach activators, enzymes, pH regulators, perfumes, perfume carriers, 25 fluorescers, dyes, foam inhibitors, silicone oils, redeposition inhibitors, optical brighteners, discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors. These substances are described in the foregoing.
The tablets according to the invention are produced by first dry-mixing the ingredients - which may be completely or partly pregranulated -30 and then shaping/forming, morre particularly tabletting, the resulting mixture using conventional processes. To produce the tablets according to the invention, the premix is compacted between two punches in a die to form a solid compactate. This process, which is referred to in short hereinafter as tabletting, comprises four phases, namely metering, compacting (elastic deformation), plastic deformation and ejection.
The premix is first introduced into the die, the filling level and hence the weight and shape of the tablet formed being determined by the position of the lower punch and the shape of the die. Uniform dosing, even at high tablet throughputs, is preferably achieved by volumetric dosing of the 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 positions by means of curved guide rails. At those places where the punches have to be raised or lowered to a particularly significant extent (filling, compaction, ejection), these curved guide rails are supported by additional push-down members, pull-down rails and ejection paths. The die is filled from a rigidly arranged feed unit, the so-called filling shoe, which is connected to a storage container for the premix. The pressure applied to the premix can be individually adjusted through the tools for the top and bottom punches, pressure being built up by the rolling of the punch shank heads past adjustable pressure rollers.
To increase throughput, rotary presses can also be equipped with two filling shoes so that only half a circle has to be negotiated to produce a tablet. To produce two-layer or multiple-layer tablets, several filling shoes are arranged one behind the other without the lightly compacted first layer being ejected before further filling. Given suitable process control, shell and bull's-eye tablets - which have a structure resembling an onion skin -can also be produced in this way. In the case of bull's-eye tablets, the upper surface of the core or rather the core layers is not covered and thus remains visible. Rotary tablet presses can also be equipped with single or multiple punches so that, for example, an outer circle with 50 bores and an inner circle with 35 bores can be simultaneously used for tabletting.
Modern rotary tablet presses have throughputs of more than one million tablets per hour.
Where rotary presses are used for tabletting, it has proved to be of advantage to carry out the tabletting process with minimal variations in the weight of the tablets. Variations in tablet hardness can also be reduced in this way. Minimal variations in weight can be achieved as follows:
- using plastic inserts with minimal thickness tolerances - low rotor speed - large filling shoe - adapting the rotational speed of the filling shoe blade to the rotor speed - filling shoe with constant powder height - decoupling the filling shoe from the powder supply Any of the nonstick coatings known in the art may be used to reduce caking on the punch. Plastic coatings, plastic inserts or plastic punches are particularly advantageous. Rotating punches have also proved to be of advantage; if possible, the upper and lower punches should be designed for rotation. If rotating punches are used, there will generally be no need for a plastic insert. In that case, the surfaces of the punch should be electropolished.
It has also been found that long tabletting times are advantageous.
These can be achieved by using pressure rails, several pressure rollers or low rotor speeds. Since variations in tablet hardness are caused by variations in the pressures applied, systems which limit the tabletting pressure should be used. Elastic punches, pneumatic compensators or spring elements in the force path may be used. The pressure roller can also be spring-mounted.
Tabletting machines suitable for the purposes of the invention can be obtained, for example, from the following companies: Apparatebau Holzwarth GbR, Asperg; Wilhelm Fette GmbH, Schwarzenbek; Hofer GmbH, Weil; Horn & Noack Pharmatechnik GmbH, Worms; IMA
Verpackungssysteme GmbH Viersen; KILIAN, Cologne; KOMAGE, Kell am See, KORSCH Pressen GmbH, Berlin; and Romaco GmbH, Worms. Other suppliers are, for example Dr. Herbert Pete, Vienna (AU); Mapag Maschinenbau AG, Bern (Switzerland); BWI Manesty, Liverpool (GB); I.
Holand Ltd., Nottingham (GB); and Courtoy N.V., Halle (BE/LU) and Medicopharm, Kamnik (SI). One example of a particularly suitable tabletting machine is the model HPF 630 hydraulic double-pressure press manufactured by LAEIS, D. Tabletting tools are obtainable, for example, from Adams Tablettierwerkzeuge Dresden; Wilhelm Fett GmbH, Schwarzenbek; Klaus Hammer, Solingen; Herber & Sohne GmbH, Hamburg; Hofer GmbH, Weil; Horn & Noack, Pharmatechnik GmbH, Worms; Ritter Pharmatechnik GmbH, Hamburg; Romaco GmbH, Worms and Notter Werkzeugbau, Tamm. Other suppliers are, for example, Senss AG, Reinach (CH) and Medicopharm, Kamnik (SI).
The tablets can be made in certain shapes and certain sizes.
Suitable shapes are virtually any easy-to-handle shapes, for example slabs, bars, cubes, squares and corresponding shapes with flat sides and, in particular, cylindrical forms of circular or oval cross-section. This last embodiment encompasses shapes from tablets to compact cylinders with a height-to-diameter ratio of more than 1.
The portioned pressings may be formed as separate individual elements which correspond to a predetermined dose of the detergent.
However, it is also possible to form pressings which combine several such units in a single pressing, smaller portioned units being easy to break off in particular through the provision of predetermined weak spots. For the use 5 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 10 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 15 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 20 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 25 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 30 performance properties. If, for example, the tablets contain components which adversely affect one another, one component may be integrated in the more quickly dissolving layer while the other component may be incorporated in a more slowly dissolving layer so that the first component can already have reacted off by the time the second component dissolves.
The various layers of the tablets can be arranged in the form of a stack, in which case the inner layers) dissolve at the edges of the tablet before the outer layers have completely dissolved. Alternatively, however, the inner layers) may also be completely surrounded by the layers lying further to the outside which prevents constituents of the inner layers) from dissolving prematurely.
In another preferred embodiment of the invention, a tablet consists of at least three layers, i.e. two outer layers and at least one inner layer, a peroxy bleaching agent being present in at least one of the inner layers whereas, in the case of the stack-like tablet, the two cover layers and, in the case of the envelope-like tablet, the outermost layers are free from peroxy bleaching agent. In another possible embodiment, peroxy bleaching agent and any bleach activators or bleach catalysts present and/or enzymes may be spatially separated from one another in one and the same tablet. Multilayer tablets such as these have the advantage that they can be used not only via a dispensing compartment or via a dosing unit which is added to the wash liquor, instead it is also possible in cases such as these to introduce the tablet into the machine in direct contact with the fabrics without any danger of spotting by bleaching agent or the like.
Similar effects can also be obtained by coating individual constituents of the detergent composition to be compressed or the tablet as a whole. To this end, the tablets to be coated may be sprayed, for example, with aqueous solutions or emulsions or a coating may be obtained by the process known as melt coating.
After pressing, the detergent tablets have high stability. The fracture resistance of cylindrical tablets can be determined via the diametral fracture stress. This in turn can be determined in accordance with the following equation:

a=
~Dt where a represents the diametral fracture stress (DFS) in Pa, P is the force in N which leads to the pressure applied to the tablet that results in fracture thereof, D is the diameter of the tablet in meters and t is its height.
The 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 unnecessarily.

Claims

1. A single- or multi-phase tablet of compacted particulate detergent comprising bleaching agents, bleach activator(s) and optionally other detergent ingredients, wherein the the tablet or at least one phase thereof contains as bleach activator a cationic nitrite corresponding to formula (I):
in which R1 represents -H, -CH3, a C2-24 alkyl or alkenyl group, a substituted C2-24 alkyl or alkenyl group with at least one substituent from the group consisting of -C1, -Br, -OH, -NH2, -CN, an alkyl or alkenyl aryl group containing a C1-24 alkyl group or a substituted alkyl or alkenyl aryl group containing a C1-24 alkyl group and at least one other substituent at the aromatic ring, R2 ad R3 independently of one another are selected from -CH2-CN, -CH3, -CH2-CH3, -CH2-CH2-CH3, -CH(CH3)-CH3, -CH2-OH, -CH2-CH2-OH, -CH(OH)-CH3, -CH2-CH2-CH2-OH, -CH2-CH(OH)-CH3, -CH(OH)-CH2-CH3, -(CH2CH2-O)n H where n = 1, 2, 3, 4, 5 or 6 and X is an anion, the pH value of a 1 % by weight aqueous solution of the tablet or the phase containing the nitriloquat being below 10.

2. A tablet as claimed in claim 1, wherein the pH value of a 1% by weight aqueous solution of the tablet or the phase containing the nitriloquat is below 9.

3. A tablet as claimed in claim 2, wherein the pH value is below 8.

4. A tablet as claimed in claim 3, wherein the pH value is below 7.

5. A tablet as claimed in claim 4, wherein the pH value is below 6.

6. A tablet as claimed in anyone of claims 1 to 5, wherein there is present a cationic nitrite corresponding to formula (I) in quantities of 0.1 to 20% by weight, based on the weight of the tablet.

7. A tablet as claimed in claim 6, wherein the quantity is 0.25 to 15% by weight.

8. A tablet as claimed in claim 7, wherein the quantity is 0.5 to 10% by weight

9. A tablet as claimed in any of claims 1 to 8, wherein there is present a cationic nitrite corresponding to formula (la):
where R4, R5 and R6 independently of one another are selected from -CH3, -CH2-CH3, -CH2-CH2-CH3, -CH(CH3)-CH3, in addition to which R4 may even be -H, and X is an anion; preferably R5 = R6 = -CH3 and, more preferably, R4=R5=R6=-CH3.

10. A tablet as claimed in any of claims 1 to 9, wherein there is present (CH3)3N(+)CH2-CN X-, where X- is an anion selected from the group consisting of chloride, bromide, iodide, hydrogen sulfate, methosulfate, p-toluene sulfonate (tosylate) or xylene sulfonate, as the cationic nitrite.

11. A tablet as claimed in any of claims 1 to 10, wherein there is present a cationic nitrile corresponding to formula (I) and tetraacetyl ethylenediamine (TAED) as bleach activators.

12. A tablet as claimed in any of claims 1 to 11, wherein there is also present a disintegration aid, in quantities of 0.5 to 10% by weight, based on the weight of the tablet.

13. A tablet as claimed in claim 12, wherein there is present a cellulose based disintegration aid.

14. A tablet as claimed in claim 12 or 13 wherein the disintegration aid is present in granular, co-granulated or compacted form.

15. A tablet as claimed in claim 12, 13 or 14 wherein the quantity is 3 to 7% by weight.

16. A tablet as claimed in claim 15, wherein the quantity is 4 to 6% by weight.

17. A tablet as claimed in any of claims 1 to 16, wherein there is present anionic and/or nonionic surfactant(s) whereby the total surfactant content is above 2.5% by weight, based on the weight of the tablet.

18. A tablet as claimed in claim 17, wherein the content is above 5% by weight.

19. A tablet as claimed in claim 18, wherein the content is above 10% by weight.

20. A two- or multi-phase detergent tablet as claimed in any of claims 1 to 19, wherein one phase contains the cationic nitrile of formula (I) in quantities of 2.5% by weight, based on the weight of the phase while the other phases) is/are preferably free from the cationic nitrile of formula (I).

21. A two- or multi-phase tablet as claimed in claim 20, wherein the quantity is 5% by weight.

22. A two- or multi-phase tablet as claimed in claim 21, wherein the quantity is 7.5% by weight.

23. A two-or multi-phase tablet as claimed in claim 20, 21, or 22 wherein the other phase or phases is free from all bleach activators.

24. A two- or multi-phase detergent tablet as claimed in claim 11, wherein one phase contains the cationic nitrile of formula (I) while another phase contains all the bleaching agent present in the tablets.

25. A two- or multi-phase detergent tablet as claimed in anyone of claims 17 to 20, wherein there is present the cationic nitrile of formula (I), bleaching agent and enzymes, and the enzymes are not present in the same phase as the bleaching agent and the cationic nitrile.

26. A two- or multi-phase detergent tablet as claimed in any of claims 17 to 24, wherein there is present the cationic nitrile of formula (I), bleaching agent and silver protectors, and the silver protectors are not present in the same phase as the bleaching agent and the cationic nitrile.

27. A process for the production of single- or multi-phase detergent tablets by tabletting one or more particulate premixes in known manner, characterized in that the premix for the entire tablet or for at least one of the phases contains a cationic nitrile corresponding to formula (I):
in which R1 represents -H, -CH3, a C2-24 alkyl or alkenyl group, a substituted C2-24 alkyl or alkenyl group with at least one substituent from the group consisting of -C1, -Br, -OH, -NH2, -CN, an alkyl or alkenyl aryl group containing a C1-24 alkyl group or a substituted alkyl or alkenyl aryl group containing a C1-24 alkyl group and at least one other substituent at the aromatic ring, R2 ad R3 independently of one another are selected from -CH2-CN, -CH3, -CH2-CH3, -CH2-CH2-CH3, -CH(CH3)-CH3, -CH2-OH, -CH2-CH2-OH, -CH(OH)-CH3, -CH2-CH2-CH2-OH, -CH2-CH(OH)-CH3, -CH(OH)-CH2-CH3, -(CH2CH2-O)n H where n = 1, 2, 3, 4, 5 or 6 and X is an anion, the pH value of a 1 % by weight aqueous solution of the particular premix being below 10.

28. A process as claimed in claim 27, wherein the pH value of a 1 % by weight aqueous solution of the premix for the entire tablet or for the phase containing the cationic nitrile of formula (I) is below 9.

29. A process as claimed in claim 28, wherein the pH is below 8.

30. A process as claimed in claim 29, wherein the pH is below 7.

31. A process as claimed in claim 30, wherein the pH is below 6.

32. A process as claimed in anyone of claims 27 to 31, wherein the premix contains (CH3)3N(+)CH2-CN X-, where X- is an anion selected from the group consisting of chloride, bromide, iodide, hydrogen sulfate, methosulfate, p-toluene sulfonate (tosylate) or xylene sulfonate, as the cationic nitrile.

33. A process as claimed in any of claims 27 to 32, wherein the particulate premix additionally contains surfactant-containing granules and has a bulk density of at least 500 g/l.

34. A process as claimed in claim 33, wherein the bulk density is at least 600 g/l.

35. A process as claimed in claim 34, wherein the bulk density is at least 700 g/l.

36. A process as claimed in anyone of claims 33 to 35, wherein surfactant-containing granules have particle sizes of 100 to 2000 µm.

37. A process as claimed in claim 36 wherein the particle sizes are 200 to 1500 µm.

38. A process as claimed in claim 37 wherein the particle sizes are 400 to 1600 µm.

39. A process as claimed in claim 38 wherein the particle sizes are 600 to 1400 µm.

40. A process as claimed in anyone of claims 33 to 39, wherein the surfactant-containing granules contain anionic and/or nonionic surfactants and builders and have a total surfactant contents of at least 10% by weight.

41. A process as claimed in claim 40 wherein the total surfactant content is 20% by weight.

42. A process as claimed in claim 41 wherein the total surfactant content is 25% by weight.

43. A process as claimed in any of claims 27 to 40, wherein the particulate premix additionally contains one or more substances from the group of bleaching agents, bleach activators, enzymes, pH regulators, perfumes, perfume carriers, fluorescers, dyes, foam inhibitors, silicone oils, redeposition inhibitors, optical brighteners, discoloration inhibitors, dye transfer inhibitors and corrosion inhibitors.