EP1184450B1

EP1184450B1 - Detergent tablet

Info

Publication number: EP1184450B1
Application number: EP01127422A
Authority: EP
Inventors: Lynda Anne Speed; Jeffrey Donald Painter
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1997-11-26
Filing date: 1998-11-24
Publication date: 2006-02-01
Anticipated expiration: 2018-11-24
Also published as: EP1184450A3; EP1184450A2; DK1184450T3; DE29823750U1

Description

Technical Field

The present invention relates to a detergent tablet comprising a compressed portion and a non-compressed portion wherein the compressed portion dissolves at a faster rate than the non-compressed portion and the non-compressed portion comprises a finishing additive.

Background

Detergent compositions in tablet form are known in the art. It is understood that detergent compositions in tablet form hold several advantages over detergent compositions in particulate form, such as ease of handling, transportation and storage.
Detergent tablets are most commonly prepared by pre-mixing components of a detergent composition and forming the pre-mixed detergent components into a tablet using a tablet press. Tablets are typically formed by compression of the detergent components into a tablet. However, the Applicant has found that some components of a detergent composition are adversely affected by the compression pressure used to form the tablets. These components could not previously be included in a detergent tablet composition without sustaining a loss in performance. In some cases the components may even have become unstable or inactive as a result of the compression.
Furthermore as the components of the detergent composition are compressed, the components are brought into close proximity with each other. A result of the close proximity of the components can be that certain of the components react with each other, becoming unstable, inactive or exhausted. A solution to this problem, as seen in the prior art, has been to separate detergent components that may potentially react with each other, especially when the components are compressed into tablet form. Separation of the components has been achieved by, for example, preparing multiple-layer tablets wherein the components that may potentially react with each other are contained in different layers of the tablet. Multiple-layer tablets, are traditionally prepared using multiple compression steps. Layers of the tablet that are subjected to more than one compression step are subjected to a cumulative and potentially greater overall compression pressure. An increase in compression pressure is known to decrease the rate of dissolution of the tablet with the effect that the multiple layers may not dissolve satisfactorily in use.
Other methods of achieving separation of detergent components have been described. For example EP-A 0,224,135 describes a dishwashing detergent in a form which comprises a warm water-soluble melt, into which is pressed a cold water-soluble tablet. The document teaches a detergent composition that consists of two parts, the first part dissolving in the pre-rinse and the second part dissolving in the main wash of the dishwasher.
EP-B-0,055,100 describes a lavatory block formed by combining a slow dissolving shaped body with a tablet. The lavatory block is designed to be placed in the cistern of a lavatory and dissolves over a period of days, preferably weeks. As a means of controlling the dissolution of the lavatory block, the document teaches admixing one or more solubility control agents. Examples of such solubility control agents are paradichlorobenzene, waxes, long chain fatty acids and alcohols and esters thereof and fatty alkylamides.
EP-A-224,135 describes a dishwashing detergent in a form which comprises a warm water-soluble melt, into which is pressed a cold water-soluble tablet. The document teaches a detergent composition that consists of two parts, the first part dissolving in the pre-rinse and the second part dissolving in the main wash of the dishwasher.
The Applicant has found that by providing a detergent tablet comprising a compressed portion and a non-compressed portion detergent components previously considered to be unacceptable for detergent tablets, can be incorporated into a detergent tablet. In addition, potentially reactive components of the detergent composition can be effectively separated.
A further advantage of using a detergent tablet as described herein, is the performance benefits which may be achieved in being able to prepare a detergent tablet where the compressed portion has a faster rate of dissolution than the non-compressed portion

Summary of the Invention

According to the present invention there is provided a detergent tablet comprising a compressed portion and a non-compressed portion wherein:

a) the compressed portion comprises a pre-prepared depression or mould and dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein; and
b) the non-compressed portion is at least partially retained with the mould.

In another aspect of the present invention there is provide a detergent tablet comprising a compressed portion and a non-compressed portion comprising a finishing additive wherein the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein and wherein the density of the non-compressed portion is at least 0.2 g/cm³ less than the density of the compressed portion.
In yet another aspect of the present invention there is provided a detergent tablet comprising a compressed portion and a non-compressed portion wherein:

a) the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein; and
b) the non-compressed portion comprises a finishing additive and is metasilicate-free.

In yet another aspect of the present invention there is provided a detergent tablet comprising a compressed portion and a non-compressed portion wherein:

a) the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis measured using the SOTAX dissolution test method described herein; and
b) the non-compressed portion comprises a finishing additive which is a fabric softener or a rinse aid.

Detailed Description of the Invention

The compressed portion of the present invention dissolves at a faster rate than the non-compressed portion on a weight by weight basis as measured by the Sotax dissolution test method outlined below. This difference in rate of dissolution means that components of the compressed and non-compressed portions can be delivered to the wash water at different points in the washing or rinsing cycle of the washing machine.
For the purposes of the present invention the compressed portion has a faster dissolution rate than the non-compressed portion meaning that the components of the compressed portion will be delivered to the was water before the components of the non-compressed portion. In another aspect of the present invention, the non-compressed portion dissolves at a temperature of less than 30°C. The compressed portion of the detergent tablet will begin to dissolve immediately on contact with water. Preferably at least 60%, more preferably at least 80%, most preferably at least 95% of the compressed portion dissolves in deionised water at 50°C within 12 minutes.
The non-compressed portion comprises at least one finishing additive as described later. Finishing additives are components that provide either a cleaning benefit e.g. enzyme, a soil anti-redeposition benefit e.g. organic polymeric compound or drainage benefit e.g. nonionic surfactant. The non-compressed portion also begins to dissolve on contact with water, although the slower dissolution rate of the non-compressed portion is such that less than 40%, preferably less than 20%, most preferably less than 10% or even 5% of the non-compressed portion dissolves in deionised water at 50°C within 12 minutes.
In an alternative embodiment of the present invention the non-compressed portion dissolves in the rinsing cycle of the washing machine. In this embodiment the finishing additive can be either a fabric softener or a rinse aid. The fabric softener is delivered into the rinsing cycle of a laundry washing machine after the clothes have been washed and softens the fabric. The rinse aid is delivered into the rinsing cycle of the dishwashing and improves water drainage from the dishware and provides reduced spotting and filming benefits. In this embodiment of the present invention it is envisaged that the non-compressed portion does not begin to dissolve during the first 12 minutes of the washing cycle or that it begins to dissolve in the rinsing cycle.
Delayed dissolution of the non-compressed portion is described in more detail later.

Compressed portion

The compressed portion of the detergent tablet comprises at least one detergent component but preferably comprise a mixture of more than one detergent component, which are then compressed to form a tablet. Any detergent tablet component conventionally used in known detergent tablets is suitable for incorporation into the compressed portion of the detergent tablets of this invention. Suitable active detergent components are described hereinafter. Preferred active detergent components include builder compound, surfactant, bleaching agent, bleach activator, bleach catalyst, enzyme and an alkalinity source.
Detergent component(s) present in the compressed layer may optionally be prepared in combination with a carrier and/or a binder for example water, polymer (e.g. PEG), liquid silicate. The detergent components are preferably prepared in particulate form (i.e. powder or granular form) and may be prepared by any known method, for example conventional spray drying, granulation or agglomeration.
The particulate detergent component(s) are compressed using any equipment suitable for forming compressed tablets, blocks, bricks or briquettes; described in more detail hereafter.
In a preferred embodiment the compressed portions additionally comprise a disrupting agent. The disrupting agent may be a disintegrating or effervescing agent. Suitable disintegrating agents include agents that swell on contact with water or facilitated water influx and/or efflux by forming channels in compressed and/or non-compressed portions Any known disintegrating or effervescing agent suitable for use in laundry or dishwashing applications is envisaged for use herein. Suitable disintegrating agent include starch, starch derivatives, alginates, carboxymethylcellulose (CMC), CMC-based polymers, sodium acetate, aluminium oxide. Suitable effervescing agents are those that produce a gas on contact with water. Suitable effervesing agents may be oxygen, nitrogen dioxide or carbon dioxide evolving species. Examples of preferred effervesing agents may be selected from the group consisting of perborate, percarbonate, carbonate, bicarbonate and carboxylic acids such as citric or maleic acid.
The density of the compressed portion is generally in the range of from 1.3g/cm³ to 1.9g/cm³, more preferably from 1.4g/cm³ to 1.8g/cm³, most preferably from 1.4g/cm³ to 1.7g/cm³.
Density is calculated by dividing the weight (mass) of the compressed portion by the volume of the compressed portion. The volume is calculated by multiplying the length by the width by the breadth of the compressed portion.

Non-Compressed Portion

The non-compressed comprises a finishing additive but may also comprise one or more detergent components. Detergent components suitable for incorporation in the non-compressed portion include components that interact with one or more detergent components present in the compressed portion. Where further detergent components are present in the non-compressed portion, preferred components include those that that are adversely affected by compression pressure of, for example a compression tablet press. Examples of such detergent components include, but are not limited to, enzyme, corrosion inhibitor and perfume. These components are described in more detail below.
The finishing additives and optional detergent component(s) may be in any form for example particulate (i.e. powder or granular), gel or liquid form. The non-compressed portion may also optionally comprise a carrier component. The detergent component may be present in the form of a solid, gel or liquid, prior to combination with a carrier component.
The non-compressed portion of the detergent tablet may be in solid, gel or liquid form.
The detergent tablet of the present invention requires that the non-compressed portion be delivered to the compressed portion such that the compressed portion and non-compressed portion contact each other. The non-compressed portion may be delivered to the compressed portion in solid or flowable form. Where the non-compressed portion is in solid form, it is pre-prepared, optionally shaped and then delivered to the compressed portion. The non-compressed portion is then affixed to a pre-formed compressed portion, for example by adhesion or by insertion of the non-compressed portion to a co-operating surface of the compressed portion. Preferably the compressed portion comprises a pre-prepared depression or mould into which the non-compressed portion is delivered.
The non-compressed portion is preferably delivered to the compressed portion in flowable form. The non-compressed portion is then affixed to the compressed portion for example by adhesion, by forming a coating over the non-compressed layer to secure it to the compressed portion, or by hardening, for example (i) by cooling to below the melting point where the flowable composition becomes a solidified melt; (ii) by evaporation of a solvent; (iii) by crystallisation; (iv) by polymerisation of a polymeric component of the flowable non-compressed portion; (v) through pseudoplastic properties where the flowable non-compressed portion comprises a polymer and shear forces are applied to the non-compressed portion; (vi) combining a binding agent with the flowable non-compressed portion. In an alternative embodiment the flowable non-compressed portion may be an extrudate that is affixed to the compressed portion by for example any of the mechanism described above or by expansion of the extrudate to the parameters of a mould provided by the compressed portion.
In the first of the invention the compressed portion comprises a pre-prepared depression or mould (hereafter referred to as 'mould') into which the non-compressed portion is delivered. In an alternative embodiment the surface of the compressed portion comprises more than one mould into which the non-compressed portion may be delivered. The mould(s) preferably at least partially accommodates one or more non-compressed portions. The non-compressed portion(s) is then delivered into the mould and affixed to the compressed portion as described above.
The non-compressed portion may comprise particulates. The particulates may be prepared by any known method, for example conventional spray drying, granulation, encapsulation or agglomeration. Particulates may be affixed to the compressed portion by incorporating a binding agent or by forming a coating layer over the non-compressed portion.
Where the non-compressed portion comprises a solidified melt, the melt is prepared by heating a composition comprising the finishing additive and any optional detergent and/or carrier component(s) to above its melting point to form a flowable melt. The flowable melt is then poured into a mould and allowed to cool. As the melt cools it becomes solid, taking the shape of the mould at ambient temperature. Where the composition comprises one or more carrier components, the carrier component(s) may be heated to above their melting point, and then an active detergent component may be added. Carrier components suitable for preparing a solidified melt are typically non-active components that can be heated to above melting point to form a liquid and cooled to form an intermolecular matrix that can effectively trap the finishing additive and optional detergent components. A preferred carrier component is an organic polymer that is solid at ambient temperature. Preferably the carrier component is polyethylene glycol (PEG). The compressed portion of the detergent tablet preferably provides a mould to accommodate the melt.
The flowable non-compressed portion may be in a form comprising a dissolved or suspended finishing additive and optional detergent component. The flowable non-compressed portion may harden over time to form a solid, semi solid or highly viscous liquid by any of the methods described above. In particular, the flowable non-compressed portion may harden by evaporation of a solvent. Solvents suitable for use herein may include any known solvent in which a binding or gelling agent is soluble. Preferred solvents may be polar, non-polar, non-aqueous or anhydrous and may include for example water, glycerine, alcohol, (for example ethanol, acetone) and alcohol derivatives. In an alternative embodiment more than one solvent may be used.
The flowable non-compressed portion may comprise one or more binding or gelling agents. Any binding or gelling agent that has the effect of causing the composition to become solid, semi-solid or highly viscous over time is envisaged for use herein. Although not wishing to be bound by theory, it is believed that mechanisms by which the binding or gelling agent causes a non-solid composition to become solid, semi-solid or highly viscous include: chemical reaction (such as chemical cross linking), or effect interaction between two or more components of the flowable compositions either; chemical or physical interaction of the binding agent with a component of the composition.
In a preferred aspect of the present invention the non-compressed portion comprises a gel. In this aspect the gel is delivered to the compressed portion of the detergent tablet, but is preferably delivered into a mould provided by the compressed portion.
The gel comprises a thickening system in addition to the finishing additive and other optional detergent components. In addition the gel may also comprise solid ingredients to aid in the control of the viscosity of the gel in conjunction with the thickening system. Solid ingredients may also act to optionally disrupt the gel thereby aiding dissolution of the gel. When included, the gel portion typically comprises at least 15% solid ingredients, more preferably at least 30% solid ingredients and most preferably at least 40% solid ingredients. However, due to the need to be able to pump and otherwise process the gel, the gel typically does not include more than 90% solid ingredients.
As noted earlier, the gel comprises a thickening system to provide the required viscosity or thickness of the gel. The thickening system typically comprises a non-aqueous liquid diluent and an organic or polymeric gelling additive:
a) Liquid Diluent: the term "solvent" or "diluent" is used herein to connote the liquid portion of the thickening system. While some of the components of the non-compressed portion may actually dissolve in the "solvent"-containing phase, other components may be present as particulate material dispersed within the "solvent"-containing phase. Thus the term "solvent" is not meant to require that the components of the non-compressed portion be capable of actually dissolving in the solvent. Suitable types of solvents useful in the non-aqueous thickening systems herein include alkylene glycol mono lower alkyl ethers, propylene glycols, ethoxylated or propoxylated ethylene or propylene, glycerol esters, glycerol triacetate, lower molecular weight polyethylene glycols, lower molecular weight methyl esters and amides.
A preferred type of non-aqueous solvent for use herein comprises the mono-, di-, tri-, or tetra- C₂-C₃ alkylene glycol mono C₂-C₆ alkyl ethers. The specific examples of such compounds include diethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol monobutyl ether. Diethylene glycol monobutyl ether and dipropylene glycol monobutyl ether are especially preferred. Compounds of the type have been commercially marketed under the tradenames Dowanol, Carbitol, and Cellosolve.
Another preferred type of non-aqueous solvent useful herein comprises the lower molecular weight polyethylene glycols (PEGs). Such materials are those having molecular weights of at least 150. PEGs of molecular weight ranging from 200 to 600 are most preferred.
Yet another preferred type of non-aqueous solvent comprises lower molecular weight methyl esters. Such materials are those of the general formula: R¹-C(O)-OCH₃ wherein R¹ ranges from 1 to 18. Examples of suitable lower molecular weight methyl esters include methyl acetate, methyl propionate, methyl octanoate, and methyl dodecanoate.
The non-aqueous organic solvent(s) employed should, of course, be compatible and nonreactive with the finishing additive and other optional detergent components, e.g. enzymes. Such a solvent component will generally be utilized in an amount of from 10% to 60% by weight of the gel portion. More preferably, the non-aqueous, low-polarity organic solvent will comprise from 20% to 50% by weight of the gel portion, most preferably from 30% to 50% by weight of the gel portion.
b) Gelling Additive: a gelling agent or additive is added to the non aqueous solvent of the present invention to complete the thickening system. To form the gel required for suitable phase stability and acceptable rheology of the gel, the organic gelling agent is generally present to the extent of a ratio of solvent to gelling agent in thickening system typically ranging from 99:1 to 1:1. More preferably, the ratios range from 19:1 to 4:1.
The preferred gelling agents of the present invention are selected from castor oil derivatives, polyethylene glycol, sorbitols and related organic thixatropes, organoclays, cellulose and cellulose derivatives, pluronics, stearates and stearate derivatives, sugar/gelatin combination, starches, glycerol and derivatives thereof, organic acid amides such as N-lauryl-L-glutamic acid di-n-butyl amide, polyvinyl pyrrolidone and mixtures thereof.
The preferred gelling agents include castor oil derivatives. Castor oil is a naturally occurring triglyceride obtained from the seeds of Ricinus Communis, a plant which grows in most tropical or subtropical areas. The primary fatty acid moiety in the castor oil triglyceride is ricinoleic acid (12-hydroxy oleic acid). It accounts for 90% of the fatty acid moieties. The balance consists of dihydroxystearic, palmitic, stearic, oleic, linoleic, linolenic and eicosanoic moieties. Hydrogenation of the oil (e.g., by hydrogen under pressure) converts the double bonds in the fatty acid moieties to single bonds, thus "hardening" the oil. The hydroxyl groups are unaffected by this reaction.
The resulting hydrogenated castor oil, therefore, has an average of about three hydroxyl groups per molecule. It is believed that the presence of these hydroxyl groups accounts in large part for the outstanding structuring properties which are imparted to the gel portion compared to similar liquid detergent compositions which do not contain castor oil with hydroxyl groups in their fatty acid chains. For use in the compositions of the present invention the castor oil should be hydrogenated to an iodine value of less than 20, and preferably less than 10. Iodine value is a measure of the degree of unsaturation of the oil and is measured by the "Wijis Method," which is well-known in the art. Unhydrogenated castor oil has an iodine value of from 80 to 90.
Hydrogenated castor oil is a commercially available commodity being sold, for example, in various grades under the trademark CASTORWAX.RTM. by NL Industries, Inc., Highstown, New Jersey. Other Suitable hydrogenated castor oil derivatives are Thixcin R, Thixcin E, Thixatrol ST, Perchem R and Perchem ST, made by Rheox, Laporte. Especially preferred is Thixatrol ST.
Polyethylene glycols when employed as gelling agents, rather than solvents, are low molecular weight materials, having a molecular weight range of from 1000 to 10,000, with 3,000 to 8,000 being the most preferred.
Cellulose and cellulose derivatives when employed in the present invention preferably include: i) Cellulose acetate and Cellulose acetate phthalate (CAP); ii) Hydroxypropyl Methyl Cellulose (HPMC); iii) Carboxymethylcellulose (CMC); and mixtures thereof. The hydroxypropyl methylcellulose polymer preferably has a number average molecular weight of 50,000 to 125,000 and a viscosity of a 2 wt.% aqueous solution at 25°C (ADTMD2363) of 50,000 to 100,000 cps. An especially preferred hydroxypropyl cellulose polymer is Methocel® J75MS-N wherein a 2.0 wt.% aqueous solution at 25°C. has a viscosity of about 75,000 cps.
The sugar may be any monosaccharide (e.g. glucose), disaccharide (e.g. sucrose or maltose) or polysaccharide. The most preferred sugar is commonly available sucrose. For the purposes of the present invention type A or B gelatin may be used, available from for example Sigma. Type A gelatin is preferred since it has greater stability in alkaline conditions in comparison to type B. Preferred gelatin also has a bloom strength of between 65 and 300, most preferably between 75 and 100.
The gel may include a variety of other ingredients in addition to the thickening agent as herein before described and the finishing additive described in more detail below. Ingredients such as dyes may be included as well as structure modifying agents. Structure modifying agents include various polymers and mixtures of polymers included polycarboxylates, carboxymethylcelluloses and starches to aid in adsorption of excess solvent and/or reduce or prevent "bleeding" or leaking of the solvent from the gel portion, reduce shrinkage or cracking of the gel portion or aid in the dissolution or breakup of the gel portion in the wash. In addition, hardness modifying agents may incorporated into the thickening system to adjust the hardness of the gel if desired. These hardness control agents are typically selected from various polymers, such as polyethylene glycol's, polyethylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, hydroxystearic acid and polyacetic acid and when included are typically employed in levels of less than 20% and more preferably less than 10% by weight of the solvent in the thickening system.
The gel is formulated so that it is a pumpable, flowable gel at slightly elevated temperatures of around 30°C or greater to allow increased flexibility in producing the detergent tablet, but becomes highly viscous or hardens at ambient temperatures so that the gel is maintained in position on the compressed portion of the detergent tablet through shipping and handling of the detergent tablet. Such hardening of the gel may achieved, for example, by (i) cooling to below the flowable temperature of the gel or the removal of shear; (ii) by solvent transfer, for example either to the atmosphere of the compressed body portion; or by (iii) by polymerisation of the gelling agent. Preferably, the gel is formulated such that it hardens sufficiently so that the maximum force needed to push a probe into the non-compressed portion preferably ranges from 0.5N to 40N. This force may be characterised by measuring the maximum force needed to push a probe, fitted with a strain gauge, a set distance into the gel. The set distance may be between 40% and 80% of the total gel depth. This force can be measured on a QTS 25 tester, using a probe of 5 mm diameter. Typical forces measured are in the range of 1N to 25N.
Where the non-compressed portion is an extrudate, the extrudate is prepared by premixing detergent components of the non-compressed portion with optional carrier components to form a viscous paste. The viscous paste is then extruded using any suitable commonly available extrusion equipment such as for example a single or twin screw extruder available from for example APV Baker, Peterborough, U.K. The extrudate is then cut to size either after delivery to the compressed portion, or prior to delivery to the compressed portion of the detergent tablet. In some aspects of the invention the compressed portion of the tablet preferably comprises a mould into which the extruded non-compressed portion may be delivered.
In a preferred embodiment the non-compressed portion is coated with a coating layer. The coating may be used to affix a non-compressed portion to the compressed portion. This may be particularly advantageous where the non-compressed portion comprises flowable particulates, gels or liquids.
The coating layer preferably comprises a material that becomes solid on contacting.the compressed and/or the non-compressed portions within preferably less than 15 minutes, more preferably less than 10 minutes, even more preferably less than 5 minutes, most preferably less than 60 seconds. Preferably the coating layer is water-soluble. Preferred coating layers comprise materials selected from the group consisting of fatty acids, alcohols, diols, esters and ethers, adipic acid, carboxylic acid, dicarboxylic acid, polyvinyl acetate (PVA), polyvinyl pyrrolidone (PVP), polyacetic acid (PLA), polyethylene glycol (PEG) and mixtures thereof. Preferred carboxylic or dicarboxylic acids preferably comprise an even number of carbon atoms. Preferably carboxylic or dicarboxylic acids comprise at least 4, more preferably at least 6, even more preferably at least 8 carbon atoms, most preferably between 8 and 13 carbon atoms. Preferred dicarboxylic acids include adipic acid, suberic acid, azelaic acid, subacic acid, undecanedioic acid, dodecandioic acid, tridecanedioic and mixtures thereof. Preferred fatty acids are those having a carbon chain length of from C12 to C22, most preferably from C18 to C22. The coating layer may also preferably comprise a disrupting agent. Where present the coating layer generally present at a level of at least 0.05%, preferably at least 0.1%, more preferably at least 1%, most preferably at least 2% or even at least 5% of the detergent tablet.
As an alternative embodiment the coating layer may encapsulate the detergent tablet. In this embodiment the coating layer is present at a level of at least 4%, more preferably at least 5%, most preferably at least 10% of the detergent tablet.
The density of the non-compressed portion is generally from 0.7g/cm³ to 1.2g/cm³, more preferably from 0.8g/cm³ to 1.2g/cm³, most preferably from 0.9g/cm³ to 1.1g/cm³. The density of the non-compressed portion is preferably at least 0.2g/cm³, more preferably at least 0.3g/cm³, most preferably at least 0.4g/cm³ less than the density of the compressed portion.
Density Measurement of the non-compressed portion: Preferably the density of the non-compressed portion is measured using a simple funnel and cup device consisting of a conical funnel moulded rigidly on a base and provided with a flap valve at its lower extremity to allow the contents of the funnel to be emptied into an axially aligned cylindrical cup of known volume disposed below the funnel. The funnel is 130 mm high and has internal diameters of 130 mm and 40 mm at its respective upper and lower extremities. It is mounted so that the lower extremity is 140 mm above the upper surface of the base. The cup has an overall height of 90 mm, an internal height of 87 mm and an internal diameter of 84 mm. Its nominal volume is 500 ml.
A density measurement is taken by hand pouring the non-compressed into the funnel. Once the funnel is filled, the flap valve is opened and powder allowed to run through the funnel, overfilling the cup. The filled cup is removed from the frame and excess non-compressed portion removed from the cup by passing a straight edged implement e.g. a knife, across its upper edge. The filled cup is then weighed. The weight of the non-compressed portion is calculated by subtracting the weight of the cup from the weight of the cup plus the non-compressed portion. Density is then calculated by dividing the weight (mass) of the non-compressed portion by the volume of the cup. Replicate measurements are made as required.
The detergent tablet of the present invention is manufactured in according to a process described herein.

Delayed dissolution of the non-compressed portion

Delayed dissolution of the non-compressed portion may be achieved by, for example selecting particulate detergent components for use as components of the non-compressed portion that are encapsulated with a component which is slow dissolving or partially soluble in water. Such encapsulating materials include cellulose and cellulose derivativese.g. cellulose acetate, cellulose acetate phthalate (CAP), hydroxypropyl Methyl Cellulose (HPMC), carboxymethylcellulose (CMC) and mixtures thereof. The hydroxypropyl methylcellulose polymer preferably has a number average molecular weight of 50,000 to 200,000 and a viscosity of a 2 wt.% aqueous solution at 25°C (ADTMD2363) of 50,000 to 120,000 cps. An especially preferred hydroxypropyl cellulose polymer is Methocel® J75MS-N wherein a 2.0 w-t.% aqueous solution at 25°C has a viscosity of about 75,000 cps. Other preferred encapsulating materials include gelatine of bloom strength in the range of from 30 to 200, preferably from 75 to 200.
The thickness of the encapsulating material will determine the dissolution rate of the encapsulated detergent component and thus the delivery rate of the detergent component to the wash water. The encapsulated detergent components are then delivered to the' compressed portion or are preferably suspended in a matrix of liquid or preferably gel that is delivered to the compressed portion. The non-compressed portion is adhered to the compressed portion by the methods described above.
Another example of a means by which the dissolution of the non-compressed portion may be delayed is premixing detergent components in a matrix which is slow dissolving or partially soluble in water. A particularly preferred matrix is a gel or viscous liquid as described above. The gel matrix preferably comprises organic or inorganic polymers. Preferred polymers include polyethylene glycol of molecular weight from 1,000 to 20,000, more preferably from 4,000 to 10,000 or even 12,000.
Yet another example of a means by which the dissolution of the non-compressed portion may be delayed is preparing a non-compressed portion as described above, then delivering the non-compressed portion to the compressed portion and coating the non-compressed portion with a coating layer as described above.
In yet another example the non-compressed portion is such that it comprises at least one component which react with an outside stimulus, such as temperature or pH, to initiate dissolution. An example of a component that would initiate dissolution on reaction to a change in temperature is a wax. In particular it is envisaged that a suitable wax will have a melting temperature above room temperature, preferably above 40°C, most preferably above 50°C.
SOTAX Dissolution Test Method: The SOTAX machine consists of a temperature controlled waterbath with lid. 7 pots are suspended in the water bath. 7 electric stirring rods are suspended from the underside of the lid, in positions corresponding to the position of the pots in the waterbath. The lid of the waterbath also serves as a lid on the pots.
The SOTAX waterbath is filled with water and the temperature gauge set to 50°C. Each pot is then filled with 1 litre of deionised water and the stirrer set to revolve at 250rpm. The lid of the waterbath is closed, allowing the temperature of the deionised water in the pots to equilibrate with the water in the waterbath for 1 hour.
Equal weight of the compressed and non-compressed portions are weighed out. The compressed portion is placed in a first pot and the non-compressed portion is placed in a second pot. The lid is then closed. The compressed and non-compressed portions are visually monitored until they completely dissolves. The time is noted when the compressed portion and the non-compressed portions have completely dissolved. The dissolution rate of the compressed portion or non-compressed portion is calculated as the average weight (g) of each portion dissolved in deionised water per minute.

Finishing additive

The non-compressed portion of the present invention comprises a finishing additive. By the term finishing additive it is meant an additive which is released into the latter stages of the washing cycle or into the rinsing cycle of a laundry washing or dishwashing machine.
Finishing additives suitable for use herein are selected from the group consisting of organic polymeric compound, enzymes, perfume component, oxygen releasing bleaching agent, precursor or catalyst, bleach destroying agent, co-builder, crystal growth inhibitor, surfactant, cationic fabric softening agent and a rinse aid.

Bleaching agent

Suitable bleaching agents for incorporation into the compressed portion include both oxygen releasing and chlorine bleaching agents. Bleaching agents suitable for use as finishing additive are oxygen-releasing bleaching agents.
The oxygen-releasing bleaching agent contains a hydrogen peroxide source and an organic peroxyacid bleach precursor compound. The production of the organic peroxyacid occurs by an in situ reaction of the precursor with a source of hydrogen peroxide. Preferred sources of hydrogen peroxide include inorganic perhydrate bleaches. In an alternative preferred aspect a preformed organic peroxyacid is incorporated directly into the composition. Compositions containing mixtures of a hydrogen peroxide source and organic peroxyacid precursor in combination with a preformed organic peroxyacid are also envisaged.

Inorganic perhydrate bleaches

The oxygen-releasing bleach preferably is a hydrogen peroxide source. Suitable hydrogen peroxide sources include the inorganic perhydrate salts.
The inorganic perhydrate salts are normally incorporated in the form of the sodium salt at a level of from 1% to 40% by weight, more preferably from 2% to 30% by weight and most preferably from 5% to 25% by weight of the compositions.
Examples of inorganic perhydrate salts include perborate, percarbonate, perphosphate, persulfate and persilicate salts. The inorganic perhydrate salts are normally the alkali metal salts. The inorganic perhydrate salt may be included as the crystalline solid without additional protection. For certain perhydrate salts however, the preferred executions of such granular compositions utilize a coated form of the material which provides better storage stability for the perhydrate salt in the granular product.
Sodium perborate can be in the form of the monohydrate of nominal formula NaBO₂H₂O₂ or the tetrahydrate NaBO₂H₂O₂.3H₂O.
Alkali metal percarbonates, particularly sodium percarbonate are preferred perhydrates for inclusion in compositions in accordance with the invention.

Peroxyacid bleach precursor

Peroxyacid bleach precursors are compounds which react with hydrogen peroxide in a perhydrolysis reaction to produce a peroxyacid. Generally peroxyacid bleach precursors may be represented as

where L is a leaving group and X is essentially any functionality, such that on perhydrolysis the structure of the peroxyacid produced is
Peroxyacid bleach precursor compounds are preferably incorporated at a level of from 0.5% to 20% by weight, more preferably from 1% to 10% by weight, most preferably from 1.5% to 5% by weight of the compositions.
Suitable peroxyacid bleach precursor compounds typically contain one or more N- or O-acyl groups, which precursors can be selected from a wide range of classes. Suitable classes include anhydrides, esters, imides, lactams and acylated derivatives of imidazoles and oximes. Examples of useful materials within these classes are disclosed in GB-A-1586789. Suitable esters are disclosed in GB-A-836988, 864798, 1147871, 2143231 and EP-A-0170386.

Metal-containing bleach catalyst

Where the compressed portion or the non-compressed portion of the present invention contain an oxygen-releasing bleaching agent, a preferred additional component is a metal containing bleach catalyst. Preferably the metal containing bleach catalyst is a transition metal containing bleach catalyst, more preferably a manganese or cobalt-containing bleach catalyst.
A suitable type of bleach catalyst is a catalyst comprising a heavy metal cation of defined bleach catalytic activity, such as copper, iron cations, an auxiliary metal cation having little or no bleach catalytic activity, such as zinc or aluminium cations, and a sequestrant having defined stability constants for the catalytic and auxiliary metal cations, particularly ethylenediaminetetraacetic acid, ethylenediaminetetra(methylenephosphonic acid) and water-soluble salts thereof. Such catalysts are disclosed in U.S. Pat. 4,430,243.
The most preferred cobalt catalyst useful herein are cobalt pentaamine acetate salts having the formula [Co(NH₃)₅OAc] T_y, wherein OAc represents an acetate moiety, and especially cobalt pentaamine acetate chloride, [Co(NH₃)₅OAc]Cl₂; as well as [Co(NH₃)₅OAc](OAc)₂; [Co(NH₃)₅OAc](PF₆)₂; [Co(NH₃)₅OAc](SO₄); [Co (NH₃)₅OAc](BF₄)₂; and [Co(NH₃)₅OAc](NO₃)₂ (herein "PAC").
These catalysts may be co-processed with adjunct materials so as to reduce the colour impact if desired for the aesthetics of the product, or to be included in enzyme-containing particles as exemplified hereinafter, or the compositions may be manufactured to contain catalyst "speckles".

Enzymes

Suitable enzymes for incorporation into the compressed portion or the non-compressed portion as a finishing additive, are selected from the group consisting of cellulases, hemicellulases, peroxidases, proteases, gluco-amylases, amylases, xylanases, lipases, phospholipases, esterases, cutinases, pectinases, keratanases, reductases, oxidases, phenoloxidases, lipoxygenases, ligninases, pullulanases, tannases, pentosanases, malanases, β-glucanases, arabinosidases, hyaluronidase, chondroitinase, laccase or mixtures thereof.
Preferred enzymes include protease, amylase, lipase, peroxidases, cutinase and/or cellulase in conjunction with one or more plant cell wall degrading enzymes.
Cellulases and/or peroxidases are normally incorporated in the detergent composition at levels from 0.0001% to 2% of active enzyme by weight of the detergent composition.
The lipases and/or cutinases are normally incorporated in the detergent composition at levels from 0.0001% to 2% of active enzyme by weight of the detergent composition.
The proteolytic enzymes are incorporated in the detergent compositions of the present invention a level of from 0.0001% to 2%, preferably from 0.001% to 0.2%, more preferably from 0.005% to 0.1% pure enzyme by weight of the composition.
Preferred amylase enzymes include those described in WO95/26397.
The amyiblylic enzymes are incorporated in the detergent compositions of the present invention a level of from 0.0001% to 2%, preferably from 0.00018% to 0.06%, more Preferably from 0.00024% to 0.048% pure enzyme by weight of the composition
In a particularly preferred embodiment, detergent tablets of the present invention comprise amylase enzymes, particularly those described in WO95/26397 in combination with a complementary amylase.
Other suitable detergent ingredients that can be added are enzyme oxidation scavengers. Examples of such enzyme oxidation scavengers are ethoxylated tetraethylene polyamines.
A range of enzyme materials and means for their incorporation into synthetic detergent compositions is also disclosed in WO 9307263 A and WO 9307260 A to Genencor International, WO 8908694 A to Novo, and U.S. 3,553,139, January 5, 1971 to McCarty et al. Enzymes are further disclosed in U.S. 4,101,457, Place et al,. July 18, 1978, and in U.S. 4,507,219, Hughes, March 26, 1985. Enzyme materials useful for liquid detergent formulations, and their incorporation into such formulations, are disclosed in U.S. 4,261,868, Hora et al, April 14, 1981. Enzymes for use in detergents can be stabilised by various techniques. Enzyme stabilisation techniques are disclosed and exemplified in U.S. 3,600,319, August 17, 1971, Gedge et al, EP 199,405 and EP 200,586, October 29, 1986, Venegas. Enzyme stabilisation systems are also described, for example, in U.S. 3,519,570. A useful Bacillus, sp. AC13 giving proteases, xylanases and cellulases, is described in WO 9401532 A to Novo.

Bleach destroying agent

A bleach destroying agent is a preferred finishing additive of the non-compressed portion of detergent tablets suitable for use in automatic dishwashing. Bleach destroying agents are delivered to the later stages of the washing cycle of a dishwashing machine and serve to destroy any remaining bleach present at the end of the washing cycle. It is believed that bleaching agent carried over from the washing cycle to the rinsing cycle causes corrosion of silverware as described in EP-A-636 888.
The bleach destroying agent consists of one or more encapsulated additives. Suitable encapsulated additives include encapsulated enzymes suitable for oxygen destruction for example peroxidases, e.g. catalase, encapsulated reducing agents, e.g. thiosulphate, encapsulated heavy metals or compounds thereof e.g. copper, iron, manganese, zinc or titanium.
Suitable methods of encapsulation are those already known in the art. The preferred encapsulation dissolve gradually e.g. paraffin.

Perfume Component

Perfume components can be incorporated into the compressed portion, but are preferably incorporated as finishing additives of the non-compressed portion. By perfume component it is meant perfume oil, encapsulated perfumes, perfumes wich have been applied to a porous carrier and then optionally encapsulated, pro-perfumes and mixtures thereof. Suitable perfumes include those commonly available in the art.

Organic polymeric compound

Organic polymeric compounds may be incorporated into the compressed portion, but are preferably finishing additives of the non-compressed portion in accord with the invention. By organic polymeric compound it is meant essentially any polymeric organic compound commonly found in detergent compositions having dispersant, anti-redeposition, soil release agents or other detergency properties.
Organic polymeric compound is typically incorporated in the detergent compositions of the invention at a level of from 0.1% to 30%, preferably from 0.5% to 15%, most preferably from 1% to 10% by weight of the compositions.
Examples of organic polymeric compounds include the water soluble organic homo-or co-polymeric polycarboxylic acids, modified polycarboxylates or their salts in which the polycarboxylic acid comprises at least two carboxyl radicals separated from each other by not more than two carbon atoms.
Preferred commercially available acrylic acid containing polymers having a molecular weight below 15,000 include those sold under the tradename Sokalan PA30, PA20, PA15, PA10 and Sokalan CP10 by BASF GmbH, and those sold under the tradename Acusol 45N, 480N, 460N by Rohin and Haas.

Co-builder

Co-builders can be incorporated into the compressed portion, but are preferably incorporated as finishing additive of the non-compressed portion. By co-builder it is meant a compound which acts in addition to a builder compound (as described below) to sequester (chelate) heavy metal ions. These components may also have calcium and magnesium chelation capacity, but preferentially they show selectivity to binding heavy metal ions such as iron, manganese and copper.
Co-builders are generally present at a level of from 0.005% to 20%, preferably from 0.1% to 10%, more preferably from 0.25% to 7.5% and most preferably from 0.5% to 5% by weight of the compositions.
Co-builders, which are acidic in nature, having for example phosphonic acid or carboxylic acid functionalities, may be present either in their acid form or as a complex/salt with a suitable counter cation such as an alkali or alkaline metal ion, ammonium, or substituted ammonium ion, or any mixtures thereof. Preferably any salts/complexes are water soluble. The molar ratio of said counter cation to the co-builder is preferably at least 1:1.
Suitable co-builders for use herein include organic phosphonates, such as the amino alkylene poly (alkylene phosphonates), alkali metal ethane 1-hydroxy disphosphonates and nitrilo trimethylene phosphonates. Preferred among the above species are diethylene triamine penta (methylene phosphonate), ethylene diamine tri (methylene phosphonate) hexamethylene diamine tetra (methylene phosphonate) and hydroxy-ethylene 1,1 diphosphonate.
Other suitable co-builders for use herein include nitrilotriacetic acid and polyaminocarboxylic acids such as ethylenediaminotetracetic acid, ethylenetriamine pentacetic acid, ethylenediamine disuccinic acid, ethylenediamine diglutaric acid, 2-hydroxypropylenediamine disuccinic acid or any salts thereof. Especially preferred is ethylenediamine-N,N'-disuccinic acid (EDDS) or the alkali metal, alkaline earth metal, ammonium, or substituted ammonium salts thereof, or mixtures thereof. Preferred EDDS compounds are the free acid form and the sodium or magnesium salt or complex thereof.

Cationic fabric softening agents

Cationic fabric softening agents are suitable finishing additives in detergent tablets which are suitable for use in methods of laundry washing. The cationic softening agents can be delivered to the wash in the later stages of the wash cycle but are preferably delivered in the rinse cycle of the washing. Suitable cationic fabric softening agents include the water insoluble tertiary amines or dilong chain amide materials as disclosed in GB-A-1 514 276 and EP-B-0 011 340.
Cationic fabric softening agents are typically incorporated at total levels of from 0.5% to 15% by weight, normally from 1% to 5% by weight.

Crystal growth inhibitor

The non-compressed portion preferably contains a crystal growth inhibitor, preferably an organodiphosphonic acid component, incorporated preferably at a level of from 0.01% to 5%, more preferably from 0.1% to 2% by weight of the compositions.
By organo diphosphonic acid it is meant herein an organo diphosphonic acid which does not contain nitrogen as part of its chemical structure. This definition therefore excludes the organo aminophosphonates, which however may be included in compositions of the invention as heavy metal ion sequestrant components.
The organo diphosphonic acid is preferably a C₁-C₄ diphosphonic acid, more preferably a C₂ diphosphonic acid, such as ethylene diphosphonic acid, or most preferably ethane 1-hydroxy-1,1-diphosphonic acid (HEDP) and may be present in partially or fully ionized form, particularly as a salt or complex.

Nonionic surfactant

Essentially any nonionic surfactants can be included in either the compresed or non-compressed portions of the detergent tablet. Preferred, non-limiting classes of useful nonionic surfactants are listed below. Preferred nonionic surfacatnt incorpoarated into the compressed portion provide a suds suppression benefit. In a preferred aspect of the present invention, the finishing additive is a rinse aid composition (described later) comprising nonionic surfactant and a source of acidity.

Nonionic ethoxylated alcohol surfactant

The alkyl ethoxylate condensation products of aliphatic alcohols with from 1 to 25 moles of ethylene oxide are suitable for use herein. The alkyl chain of the aliphatic alcohol can either be straight or branched, primary or secondary, and generally contains from 6 to 22 carbon atoms. Particularly preferred are the condensation products of alcohols having an alkyl group containing from 8 to 20 carbon atoms with from 2 to 10 moles of ethylene oxide per mole of alcohol.

End-capped alkyl alkoxylate surfactant

A suitable endcapped alkyl alkoxylate surfactant is the epoxy-capped poly(oxyalkylated) alcohols represented by the formula:

R₁O[CH₂CH(CH₃)O]_x[CH₂CH₂O]_x[CH₂CH(OH)R₂] (I)

wherein R₁ is a linear or branched, aliphatic hydrocarbon radical having from 4 to 18 carbon atoms; R₂ is a linear or branched aliphatic hydrocarbon radical having from 2 to 26 carbon atoms; x is an integer having an average value of from 0.5 to 1.5, more preferably 1; and y is an integer having a value of at least 15, more preferably at least 20.
Preferably, the surfactant of formula I, at least 10 carbon atoms in the terminal epoxide unit [CH₂CH(OH)R₂]. Suitable surfactants of formula I, according to the present invention, are Olin Corporation's POLY-TERGENT® SLF-18B nonionic surfactants, as described, for example, in WO 94/22800, published October 13, 1994 by Olin Corporation.

Ether-capped poly(oxyalkylated) alcohols

Preferred surfactants for use herein include ether-capped poly(oxyalkylated) alcohols having the formula:

R¹O[CH₂CH(R³)O]_x[CH₂]_kCH(OH)[CH₂]_jOR²

wherein R¹ and R² are linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from 1 to 30 carbon atoms; R³ is H, or a linear aliphatic hydrocarbon radical having from 1 to 4 carbon atoms; x is an integer having an average value from 1 to 30, wherein when x is 2 or greater R³ may be the same or different and k and j are integers having an average value of from 1 to 12, and more preferably 1 to 5.
R¹ and R² are preferably linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from 6 to 22 carbon atoms with 8 to 18 carbon atoms being most preferred. H or a linear aliphatic hydrocarbon radical having from 1 to 2 carbon atoms is most preferred for R³. Preferably, x is an integer having an average value of from I to 20, more preferably from 6 to 15.
As described above, when, in the preferred embodiments, and x is greater than 2, R³ may be the same or different. That is, R³ may vary between any of the alklyeneoxy units as described above. For instance, if x is 3, R³ may be be selected to form ethlyeneoxy(EO) or propyleneoxy(PO) and may vary in order of (EO)(PO)(EO), (EO)(EO)(PO); (EO)(EO)(EO); (PO)(EO)(PO); (PO)(PO)(EO) and (PO)(PO)(PO). Of course, the integer three is chosen for example only and the variation may be much larger with a higher integer value for x and include, for example, multiple (EO) units and a much small number of (PO) units.
Particularly preferred surfactants as described above include those that have a low cloud point of less than 20°C. These low cloud point surfactants may then be employed in conjunction with a high cloud point surfactant as described in detail below for superior grease cleaning benefits.
Most preferred ether-capped poly(oxyalkylated) alcohol surfactants are those wherein k is 1 and j is 1 so that the surfactants have the formula:

R¹O[CH₂CH(R³)O]_xCH₂CH(OH)CH₂OR²

where R¹, R² and R³ are defined as above and x is an integer with an average value of from 1 to 30, preferably from 1 to 20, and even more preferably from 6 to 18. Most preferred are surfactants wherein R¹ and R² range from 9 to 14, R³ is H forming ethyleneoxy and x ranges from 6 to 15.
The ether-capped poly(oxyalkylated) alcohol surfactants comprise three general components, namely a linear or branched alcohol, an alkylene oxide and an alkyl ether end cap. The alkyl ether end cap and the alcohol serve as a hydrophobic, oil-soluble portion of the molecule while the alkylene oxide group forms the hydrophilic, water-soluble portion of the molecule.
These surfactants exhibit significant improvements in spotting and filming characteristics and removal of greasy soils, when used in conjunction with high cloud point surfactants, relative to conventional surfactants.
Generally speaking, the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention may be produced by reacting an aliphatic alcohol with an epoxide to form an ether which is then reacted with a base to form a second epoxide. The second epoxide is then reacted with an alkoxylated alcohol to form the novel compounds of the present invention. Examples of methods of preparing the ether-capped poly(oxyalkylated) alcohol surfactants are described below:

Preparation of C _12/14 alkyl glycidyl ether

A C_12/14 fatty alcohol (100.00 g, 0.515 mol.) and tin (IV) chloride (0.58 g, 2.23 mmol, available from Aldrich) are combined in a 500 mL three-necked round-bottomed flask fitted with a condenser, argon inlet, addition funnel, magnetic stirrer and internal temperature probe. The mixture is heated to 60 °C. Epichlorhydrin (47.70 g, 0.515 mol, available from Aldrich) is added dropwise so as to keep the temperature between 60-65 °C. After stirring an additional hour at 60 °C, the mixture is cooled to room temperature. The mixture is treated with a 50% solution of sodium hydroxide (61.80 g, 0.773 mol, 50%) while being stirred mechanically. After addition is completed, the mixture is heated to 90 °C for 1.5 h, cooled, and filtered with the aid of ethanol. The filtrate is separated and the organic phase is washed with water (100 mL), dried over MgSO₄, filtered, and concentrated. Distillation of the oil at 100-120 °C (0.1 mm Hg =13,3 Pa) providing the glycidyl ether as an oil.

Preparation of C _12/14 alkyl-C _9/11 ether capped alcohol surfactant

Neodol® 91-8 (20.60 g, 0.0393 mol ethoxylated alcohol available from the Shell chemical Co.) and tin (IV) chloride (0.58 g, 2.23 mmol) are combined in a 250 mL three-necked round-bottomed flask fitted with a condenser, argon inlet, addition funnel, magnetic stirrer and internal temperature probe. The mixture is heated to 60 ° C at which point (C_12/14 alkyl glycidyl ether (11.00 g, 0.0393 mol) is added dropwise over 15 min. After stirring for 18 h at 60 °C, the mixture is cooled to room temperature and dissolved in an equal portion of dichloromethane. The solution is passed through 2,54cm (1 inch) pad of silica gel while eluting with dichloromethane. The filtrate is concentrated by rotary evaporation and then stripped in a kugelrohr oven (100°C, 0.5 mm Hg=66,7Pa) to yield the surfactant as an oil.

Nonionic ethoxylated/propoxylated fatty alcohol surfactant

The ethoxylated C₆-C₁₈ fatty alcohols and C₆-C₁₈ mixed ethoxylated/propoxylated fatty alcohols are suitable surfactants for use herein, particularly where water soluble. Preferably the ethoxylated fatty alcohols are the C₁₀-C₁₈ ethoxylated fatty alcohols with a degree of ethoxylation of from 3 to 50, most preferably these are the C₁₂-C₁₈ ethoxylated fatty alcohols with a degree of ethoxylation from 3 to 40. Preferably the mixed ethoxylated/propoxylated fatty alcohols have an alkyl chain length of from 10 to 18 carbon atoms, a degree of ethoxylation of from 3 to 30 and a degree of propoxylation of from 1 to 10.

Nonionic EO/PO condensates with propylene glycol

The condensation products of ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol are suitable for use herein. The hydrophobic portion of these compounds preferably has a molecular weight of from 1500 to 1800 and exhibits water insolubility. Examples of compounds of this type include certain of the commercially-available Pluronic™ surfactants, marketed by BASF.

Nonionic EO condensation products with propylene oxide/ethylene diamine adducts

The condensation products of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylenediamine are suitable for use herein. The hydrophobic moiety of these products consists of the reaction product of ethylenediamine and excess propylene oxide, and generally has a molecular weight of from 2500 to 3000. Examples of this type of nonionic surfactant include certain of the commercially available Tetronic™ compounds, marketed by BASF.

Mixed Nonionic Surfactant System

In a preferred embodiment of the present invention the detergent tablet comprises a mixed nonionic surfactant system comprising at least one low cloud point nonionic surfactant and at least one high cloud point nonionic surfactant as described in WO-A-98/11187.
In a preferred embodiment the detergent tablet comprising such a mixed surfactant system also comprises an amount of water-soluble salt to provide conductivity in deionised water measured at 25°C greater than 3 milli Siemens/cm, preferably greater than 4 milli Siemens/cm, most preferably greater than 4.5 milli Siemens/cm.
In another preferred embodiment the mixed surfactant system dissolves in water having a hardness of 1.246mmol/L in any suitable cold-fill automatic dishwasher to provide a solution with a surface tension of less than 4 Dynes/cm² at less than 45°C, preferably less than 40°C, most preferably less than 3.5°C as described in WO-A-98/11187.
In another preferred embodiment the high cloud point and low cloud.point surfactants of the mixed surfactant system are separated such that one of either the high cloud point or low cloud point surfactants is present in a first matrix and the other is present in a second matrix as described in WO-A-98/11187. For the purposes of the present invention, the first matrix may be a first particulate and the second matrix may be a second particulate. A surfactant may be applied to a particulate by any suitable known method, preferably the surfactant is sprayed onto the particulate. In a preferred aspect the first matrix is the compressed portion and the second matrix is the non-compressed portion of the detergent tablet of the present invention. Preferably the low cloud point surfactant is present in the compressed portion and the high cloud point surfactant is present in the non-compressed portion of the detergent tablet of the present invention.

Rinse Aid

In a preferred aspect of the present invention, the non-compressed portion comprises a rinse aid. By rinse aid it is meant a composition that is delivered in the rinse cycle of the automatic dishwasher and provide improved drainage of water and reduced spot and film formation on dishware.
The rinse aid composition for use herein may comprise any of the components commonly found as components of rinse aid compositions, for example nonionic surfactants (described above), hydrotropes, solvent and a source of acidity.
Suitable hydrotropes include sodium, potassium and ammonium xylene sulfonates, toluene sulfonate, cumene sulfonates and mixtures thereof. Hydrotrope is typically present at a level of from 0.5% to 20% by weight, preferably 1% to 10% by weight of the rinse aid composition.
The rinse aid composition may contain one or more solvent at levels of from 1% to 30% by weight, preferably from 3% to 25% by weight, more preferably from 5% to 20% by weight of the rinse aid composition, particularly when in liquid or gel form. Suitable solvents for use herein include the organic solvent having the general formula RO(CH₂C(Me)HO)_nH, wherein R is an alkyl, alkenyl, or alkyl aryl group having from 1 to 8 carbon atoms, and n is an integer from 1 to 4. Preferably, R is an alkyl group containing 1 to 4 carbon atoms, and n is 1 or 2. Especially preferred R groups are n-butyl or isobutyl. Preferred solvents of this type are 1-n-butoxypropane-2-ol (n= 1); and 1(2-n-butoxy-1-methylethoxy)propane-2-ol (n=2), and mixtures thereof.
Other solvents useful herein include the water soluble CARBITOL solvents or water-soluble CELLOSOLVE solvents. Water-soluble CARBITOL solvents are compounds of the 2-(2 alkoxyethoxy)ethanol class wherein the alkoxy group is derived from ethyl, propyl or butyl; a preferred water-soluble carbitol is 2-(2-butoxyethoxy)ethanol also known as butyl carbitol. Water-soluble CELLOSOLVE solvents are compounds of the 2-alkoxyethoxy ethanol class, with 2-butoxyethoxyethanol being preferred.
Other suitable solvents are benzyl alcohol, and diols such as 2-ethyl-1,3-hexanediol and 2,2,4-trimethl-1,3-pentanediol.
The low molecular weight, water-soluble, liquid polyethylene glycols are also suitable solvents for use herein.
The alkane mono and diols, especially the C₁-C₆ alkane mono and diols are suitable for use herein. C₁-C₄ monohydric alcohols (eg: ethanol, propanol, isopropanol, butanol and mixtures thereof) are preferred, with ethanol particularly preferred. The C1-C4 dihydric alcohols, including propylene glycol, are also preferred.
The pH of the rinse aid composition is preferably less than 7. The pH is adjusted by incorporating a source of acidity for example inorganic or organic acids including for example carboxylate acids (e.g. citric acid or succinic acid), polycarboxylate acids (e.g. polyacrylic acid), acetic acid, boric acid, malonic acid, adipic acid, fumaric acid, lactic acid, glycolic aicd, tartaric acid, tartronic acid, maleic acid, derivatives and mixtures thereof. A preferred acidity source is citric acid.
The rinse aid composition may also comprise other components such as builders, co-builders and other polymeric compounds (described above), especially polyethylene glycol (PEG), polyvinyl pyrrolidone, polyacrylate (especially those described in US 5 240 632), polymethacrylate and copolymers thereof, acrylonitrile.

Process

As described above, the detergent tablets described herein are prepared by separately preparing the composition of finishing additives and/or detergent components forming the respective compressed portion and the non-compressed portion, then delivering or adhering the composition of the non-compressed portion to the compressed portion.
The compressed portion comprises at least one, but preferably more than one detergent component. The compressed portion is prepared by pre-mixing at least one, but preferably a mixture of detergent components and/or optional carrier components to form a composition. Any pre-mixing will be carried out in a suitable mixer; for example a pan mixer, rotary drum, vertical blender or high shear mixer. Preferably dry particulate components are admixed in a mixer, as described above, and liquid components are applied to the dry particulate components, for example by spraying the liquid components directly onto the dry particulate components. The resulting composition is then formed into a compressed portion in a compression step using any known suitable equipment. Preferably the composition is formed into a compressed portion using a tablet press, wherein the tablet is prepared by compression of the composition between an upper and a lower punch. In a preferred embodiment of the present invention the composition is delivered into a punch cavity of a tablet press and compressed to form a compressed portion using a pressure of preferably greater than 6.3 KN/cm², more preferably greater than 9KN/cm², most preferably greater than 14.4KN/cm².
In order to form a preferred tablet of the invention, wherein the compressed portion provides a mould to receive the non-compressed portion, the compressed portion is prepared using a modified tablet press comprising modified upper and/or lower punches. The upper and lower punches of the modified tablet press are modified such that the compressed portion provides one or more indentations which form a mould(s) to which the non-compressed portion is delivered.
The non-compressed portion comprises a finishing additive, but may also optionally comprise one or more detergent components. The components of the non-compressed portion are pre-mixed using any known suitable mixing equipment. In addition the non-compressed portion may optionally comprise a carrier with which the finishing additive and optional detergent components are combined. The non-compressed portion may be prepared in solid or flowable form. Once prepared the composition is delivered to the compressed portion. The non-compressed portion may be delivered to the compressed portion by manual delivery or using a nozzle feeder or extruder. Where the compressed portion comprises a mould, the non-compressed portion is preferably delivered to the mould using accurate delivery equipment, for example a nozzle feeder, such as a loss in weight screw feeder available from Optima, Germany or an extruder.
Where the flowable non-compressed portion is in particulate form the process comprises delivering a flowable non-compressed portion to the compressed portion in a delivery step and then coating at least a portion of the non-compressed portion with a coating layer such that the coating layer has the effect of substantially adhering the non-compressed portion to the compressed portion.
Where the flowable non-compressed portion is affixed to the compressed portion by hardening, the process comprises a delivery step in which the flowable non-compressed portion is delivered to the compressed portion and a subsequent conditioning step, wherein the non-compressed portion hardens. Such a conditioning step may comprise drying, cooling, binding, polymerisation etc. of the non-compressed portion, during which the non-compressed portion becomes solid, semi-solid or highly viscous. Heat may be used in a drying step. Heat, or exposure to radiation may be used to effect polymerisation in a polymerisation step.
It is also envisaged that the compressed portion may be prepared having a plurality of moulds. The plurality of moulds are then filled with a non-compressed portion. It is also envisaged that each mould can be filled with a different non-compressed portion or alternatively, each mould can be filled with a plurality of different non-compressed portions.

Detergent Components

The compressed portion of the detergent tablets described herein are prepared by compression composition of at least one, but preferably a mixture of detergent components. A suitable pre-mixed composition may include a variety of different detergent active components including builder compounds, surfactants, enzymes, bleaching agents (both oxygen releasing and chlorine), alkalinity sources, colourants, perfume, lime soap dispersants, organic polymeric compounds including polymeric dye transfer inhibiting agents, crystal growth inhibitors, co-builders, metal ion salts, enzyme stabilisers, corrosion inhibitors, suds suppressers, solvents, fabric softening agents, optical brighteners and hydrotropes.
Highly preferred detergent components of the compressed portion include a builder ' compound, a surfactant, enzyme and bleaching agent.

Builder compound

The detergent tablets of the present invention preferably contain a builder compound, typically present at a level of from 1% to 80% by weight, preferably from 10% to 70% by weight, most preferably from 20% to 60% by weight of the composition of active detergent components.

Water-soluble builder compound

Suitable water-soluble builder compounds include the water soluble monomeric polycarboxylates, or their acid forms, homo or copolymeric polycarboxylic acids or their salts in which the polycarboxylic acid comprises at least two carboxylic radicals separated from each other by not more that two carbon atoms, carbonates, bicarbonates, borates, phosphates, and mixtures of any of the foregoing.
The carboxylate or polycarboxylate builder can be monomeric or oligomeric in type

Partially soluble or insoluble builder compound

The detergent tablets of the present invention may contain a partially soluble or insoluble builder compound. Partially soluble and insoluble builder compounds are particularly suitable for use in tablets prepared for use in laundry cleaning methods. Examples of partially water soluble builders include the crystalline layered silicates as disclosed for example, in EP-A-0164514, DE-A-3417649 and DE-A-3742043. Preferred are the crystalline layered sodium silicates of general formula

NaMSi_xO₂₊₁ .yH₂O

wherein M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20. Crystalline layered sodium silicates of this type preferably have a two dimensional 'sheet' structure, such as the so called δ-layered structure, as described in EP 0 164514 and EP 0 293640.
The most preferred crystalline layered sodium silicate compound has the formula δ-Na₂Si₂O₅, known as NaSKS-6 (trade name), available from Hoechst AG.

Surfactant

Surfactants are preferred detergent active components of the compositions described herein. Suitable surfactants are selected from anionic, cationic, nonionic, ampholytic and zwitterionic surfactants and mixtures thereof. Automatic dishwashing machine products should be low foaming in character and thus the foaming of the surfactant system for use in dishwashing methods must be suppressed or more preferably be low foaming, typically nonionic in character. Sudsing caused by surfactant systems used in laundry cleaning methods need not be suppressed to the same extent as is necessary for dishwashing. The surfactant is typically present at a level of from 0.2% to 30% by weight, more preferably from 0.5% to 10% by weight, most preferably from 1% to 5% by weight of the composition of active detergent components.
A typical listing of anionic, nonionic, ampholytic and zwitterionic classes, and species of these surfactants, is given in U.S.P. 3,929,678 issued to Laughlin and Heuring on December, 30, 1975. A list of suitable cationic surfactants is given in U.S.P. 4,259,217 issued to Murphy on March 31, 1981. A listing of surfactants typically included in automatic dishwashing detergent compositions is given for example, in EP-A-0414 549 and PCT Applications No.s WO 93/08876 and WO 93/08874.

Water-soluble sulfate salt

The detergent tablet optionally contains a water-soluble sulfate salt. Where present the water-soluble sulfate salt is at the level of from 0.1% to 40%, more preferably from 1% to 30%, most preferably from 5% to 25% by weight of the compositions.
The water-soluble sulfate salt may be essentially any salt of sulfate with any counter cation. Preferred salts are selected from the sulfates of the alkali and alkaline earth metals, particularly sodium sulfate.

Alkali Metal Silicate

According to an embodiment of the present invention an alkali metal silicate is an essential component of the detergent tablet. In other embodiments of the present invention the presence of an alkali metal silicate is optional. A preferred alkali metal silicate is sodium silicate having an SiO₂:Na₂O ratio of from 1.8 to 3.0, preferably from 1.8 to 2.4, most preferably 2.0. Sodium silicate is preferably present at a level of less than 20%, preferably from 1% to 15%, most preferably from 3% to 12% by weight of SiO₂. The alkali metal silicate may be in the form of either the anhydrous salt or a hydrated salt.
Alkali metal silicate may also be present as a component of an alkalinity system.
The alkalinity system also preferably contains sodium metasilicate, present at a level of at least 0.4% SiO₂ by weight. Sodium metasilicate has a nominal SiO₂ : Na₂O ratio of 1.0. The weight ratio of said sodium silicate to said sodium metasilicate, measured as SiO₂, is preferably from 50:1 to 5:4, more preferably from 15:1 to 2:1, most preferably from 10:1 to 5:2.

Colourant

The term 'colourant', as used herein, means any substance that absorbs specific wavelengths of light from the visible light spectrum. Such colourants when added to a detergent composition have the effect of changing the visible colour and thus the appearance of the detergent composition. Colourants may be for example either dyes or pigments. Preferably the colourants are stable in composition in which they are to be incorported. Thus in a composition of high pH the colourant is preferably alkali stable and in a composition of low pH the colourant is preferably acid stable.
The compressed portion and/or non compressed may contain a colourant, a mixture of colourants, coloured particles or mixture of coloured particles such that the compressed portion and the non-compressed portion have different visual appearances. Preferably one of either the compressed portion or the non-compressed comprises a colourant.
Where the non-compressed portion comprises two or more compositions of active detergent components, preferably at least one of either the first and second and/or subsequent compositions comprises a colourant. Where both the first and second and/or subsequent compositions comprise a colourant it is preferred that the colourants have a different visual appearance.
Where present the coating layer preferably comprises a colourant. Where the compressed portion and the coating layer comprise a colourant, it is preferred that the colourants provide a different visual effect.
Examples of suitable dyes include reactive dyes, direct dyes, azo dyes. Preferred dyes include phthalocyanine dyes, anthraquinone dye, quinoline dyes, monoazo, disazo and polyazo. More preferred dyes include anthraquinone, quinoline and monoazo dyes. Preferred dyes include SANDOLAN E-HRL 180% (tradename), SANDOLAN MILLING BLUE (tradename), TURQUOISE ACID BLUE (tradename) and SANDOLAN BRILLIANT GREEN (tradename) all available from Clariant UK, HEXACOL QUINOLINE YELLOW (tradename) and HEXACOL BRILLIANT BLUE (tradename) both available from Pointings, UK, ULTRA MARINE BLUE (tradename) available from Holliday or LEVAFIX TURQUISE BLUE EBA (tradename) available from Bayer, USA.
The colourant may be incorporated into the compressed and/or non-compressed portion by any suitable method. Suitable methods include mixing all or selected active detergent components with a colourant in a drum or spraying all or selected active detergent components with the colourant in a rotating drum.
Colourant when present as a component of the compressed portion is present at a level of from 0.001% to 1.5%, preferably from 0.01% to 1.0%, most preferably from 0.1% to 0.3%. When present as a component of the non-compressed portion, colourant is generally present at a level of from 0.001% to 0.1%, more preferably from 0.005% to 0.05%, most preferably from 0.007% to 0.02%. When present as a component of the coating layer, colourant is present at a level of from 0.01% to 0.5%, more preferably from 0.02% to 0.1%, most preferably from 0.03% to 0.06%.

Corrosion inhibitor compound

The detergent tablets of the present invention suitable for use in dishwashing methods may contain corrosion inhibitors preferably selected from organic silver coating agents, particularly paraffin, nitrogen-containing corrosion inhibitor compounds and Mn(II) compounds, particularly Mn(II) salts of organic ligands.
Other suitable additional corrosion inhibitor compounds include, mercaptans and diols, especially mercaptans with 4 to 20 carbon atoms including lauryl mercaptan, thiophenol, thionapthol, thionalide and thioanthranol. Also suitable are saturated or unsaturated C₁₀-C₂₀ fatty acids, or their salts, especially aluminium tristearate. The C₁₂-C₂₀ hydroxy fatty acids, or their salts, are also suitable. Phosphonated octadecane and other anti-oxidants such as betahydroxytoluene (BHT) are also suitable.
Copolymers of butadiene and maleic acid, particularly those supplied under the trade reference no. 07787 by Polysciences Inc have been found to be of particular utility as corrosion inhibitor compounds.

Hydrocarbon oils

Another preferred active detergent component for use in the present invention is a hydrocarbon oil; typically a predominantly long chain, aliphatic hydrocarbons having a number of carbon atoms in the range of from 20 to 50; preferred hydrocarbons are saturated and/or branched; preferred hydrocarbon oil selected from predominantly branched C_25-45 species with a ratio of cyclic to noncyclic hydrocarbons of from 1:10 to 2:1, preferably from 1:5 to 1:1. A preferred hydrocarbon oil is paraffin. A paraffin oil meeting the characteristics as outlined above, having a ratio of cyclic to noncyclic hydrocarbons of 32:68, is sold by Wintershall, Salzbergen, Germany, under the trade name WINOG 70.

Water-soluble bismuth compound

The detergent tablets of the present invention suitable for use in dishwashing methods may contain a water-soluble bismuth compound, preferably present at a level of from 0.005% to 20%, more preferably from 0.01% to 5%, most preferably from 0.1% to 1% by weight of the compositions.
The water-soluble bismuth compound may be essentially any salt or complex of bismuth with essentially any inorganic or organic counter anion. Preferred inorganic bismuth salts are selected from the bismuth trihalides, bismuth nitrate and bismuth phosphate. Bismuth acetate and citrate are preferred salts with an organic counter anion.

Enzyme Stabilizing System

Preferred enzyme-containing compositions herein may comprise from 0.001% to 10%, preferably from 0.005% to 8%, most preferably from 0.01% to 6%, by weight of an enzyme stabilizing system. The enzyme stabilizing system can be any stabilizing system which is compatible with the detersive enzyme. Such stabilizing systems can comprise calcium ion, boric acid, propylene glycol, short chain carboxylic acid, boronic acid, chlorine bleach scavengers and mixtures thereof. Such stabilizing systems can also comprise reversible enzyme inhibitors, such as reversible protease inhibitors.

Lime soap dispersant compound

The compositions of active detergent components may contain a lime soap dispersant compound, preferably present at a level of from 0.1% to 40% by weight, more preferably 1% to 20% by weight, most preferably from 2% to 10% by weight of the compositions.
A lime soap dispersant is a material that prevents the precipitation of alkali metal, ammonium or amine salts of fatty acids by calcium or magnesium ions. Preferred lime soap disperant compounds are disclosed in PCT Application No. WO93/08877.

Suds suppressing system

The detergent tblets of the present invention, when formulated for use in machine washing compositions, preferably comprise a suds suppressing system present at a level of from 0.01% to 15%, preferably from 0.05% to 10%, most preferably from 0.1% to 5% by weight of the composition.
Suitable suds suppressing systems for use herein may comprise essentially any known antifoam compound, including, for example silicone antifoam compounds, 2-alkyl and alcanol antifoam compounds. Preferred suds suppressing systems and antifoam compounds are disclosed in PCT Application No. WO93/08876 and EP-A-705 324.

Polymeric dye transfer inhibiting agents

The detergent tablets herein may also comprise from 0.01 % to 10 %, preferably from 0.05% to 0.5% by weight of polymeric dye transfer inhibiting agents.
The polymeric dye transfer inhibiting agents are preferably selected from polyamine N-oxide polymers, copolymers of N-vinylpyrrolidone and N-vinylimidazole, polyvinylpyrrolidonepolymers or combinations thereof.

Optical brightener

The detergent tablets suitable for use in laundry washing methods as described herein, also optionally contain from 0.005% to 5% by weight of certain types of hydrophilic optical brighteners.
Hydrophilic optical brighteners useful herein include those having the structural formula:

wherein R₁ is selected from anilino, N-2-bis-hydroxyethyl and NH-2-hydroxyethyl; R₂ is selected from N-2-bis-hydroxyethyl, N-2-hydroxyethyl-N-methylamino, morphilino, chloro and amino; and M is a salt-forming cation such as sodium or potassium.
When in the above formula, R₁ is anilino, R₂ is N-2-bis-hydroxyethyl and M is a cation such as sodium, the brightener is 4,4',-bis[(4-anilino-6-(N-2-bis-hydroxyethyl)-s-triazine-2-yl)amino]-2,2'-stilbenedisulfonic acid and disodium salt. This particular brightener species is commercially marketed under the tradename Tinopal-UNPA-GX by Ciba-Geigy Corporation. Tinopal-UNPA-GX is the preferred hydrophilic optical brightener useful in the detergent compositions herein.
When in the above formula, R₁ is anilino, R₂ is N-2-hydroxyethyl-N-2-methylamino and M is a cation such as sodium, the brightener is 4,4'-bis[(4-anilino-6-(N-2-hydroxyethyl-N-methylamino)-s-triazine-2-yl)amino]2,2'-stilbenedisulfonic acid disodium salt. This particular brightener species is commercially marketed under the tradename Tinopal 5BM-GX by Ciba-Geigy Corporation.
When in the above formula, R₁ is anilino, R₂ is morphilino and M is a cation such as sodium, the brightener is 4,4'-bis((4-anilino-6-morphilino-s-triazine-2-yl)amino]2,2'-stilbenedisulfonic acid, sodium salt. This particular brightener species is commercially marketed under the tradename Tinopal AMS-GX by Ciba Geigy Corporation.

Clay softening system

The detergent tablets suitable for use in laundry cleaning methods may contain a clay softening system comprising a clay mineral compound and optionally a clay flocculating agent.
The clay mineral compound is preferably a smectite clay compound. Smectite clays are disclosed in the US Patents No.s 3,862,058, 3,948,790, 3,954,632 and 4,062,647. European Patents No.s EP-A-299,575 and EP-A-313,146 in the name of the Procter and Gamble Company describe suitable organic polymeric clay flocculating agents.

Other optional ingredients

Other optional ingredients suitable for inclusion in the compositions of the invention include perfumes and filler salts, with sodium sulfate being a preferred filler salt.

pH of the compositions

The detergent tablets of the present invention are preferably not formulated to have an unduly high pH, in preference having a pH measured as a 1% solution in distilled water of from 8.0 to 12.5, more preferably from 9.0 to 11.8, most preferably from 9.5 to 11.5.
In another aspect of the present invention the compressed and non-compressed portions are formulated to deliver different pH. In the rinse aid application described abobe, the compressed portion is formulated to deliver an alkaline pH whereas the non-compressed portion is formulated to deliver an acidic pH of less than 7, preferably between 0.5 and 6.5, most preferably between 1.0 and 5.0.

Machine dishwashing method

Any suitable methods for machine washing or cleaning soiled tableware are envisaged. A preferred machine dishwashing method comprises treating soiled articles selected from crockery, glassware, silverware, metallic items, cutlery and mixtures thereof, with an aqueous liquid having dissolved or dispensed therein an effective amount of a detergent tablet in accord with the invention. By an effective amount of the detergent tablet it is meant from 8g to 60g of product dissolved or dispersed in a wash solution of volume from 3 to 10 litres, as are typical product dosages and wash solution volumes commonly employed in conventional machine dishwashing methods. Preferably the detergent tablets are from 15g to 40g in weight, more preferably from 20g to 35g in weight.

Laundry washing method

Machine laundry methods herein typically comprise treating soiled laundry with an aqueous wash solution in a washing machine having dissolved or dispensed therein an effective amount of a machine laundry detergent tablet composition in accord with the invention. By an effective amount of the detergent tablet composition it is meant from 40g to 300g of product dissolved or dispersed in a wash solution of volume from 5 to 65 litres, as are typical product dosages and wash solution volumes commonly employed in conventional machine laundry methods.
In a preferred use aspect a dispensing device is employed in the washing method. The dispensing device is charged with the detergent product, and is used to introduce the product directly into the drum of the washing machine before the commencement of the wash cycle. Its volume capacity should be such as to be able to contain sufficient detergent product as would normally be used in the washing method.
Once the washing machine has been loaded with laundry the dispensing device containing the detergent product is placed inside the drum. At the commencement of the wash cycle of the washing machine water is introduced into the drum and the drum periodically rotates. The design of the dispensing device should be such that it permits containment of the dry detergent product but then allows release of this product during the wash cycle in response to its agitation as the drum rotates and also as a result of its contact with the wash water.
To allow for release of the detergent product during the wash the device may possess a number of openings through which the product may pass. Alternatively, the device may be made of a material which is permeable to liquid but impermeable to the solid product, which will allow release of dissolved product. Preferably, the detergent product will be rapidly released at the start of the wash cycle thereby providing transient localised high concentrations of product in the drum of the washing machine at this stage of the wash cycle.
Preferred dispensing devices are reusable and are designed in such a way that container integrity is maintained in both the dry state and during the wash cycle.
Alternatively, the dispensing device may be a flexible container, such as a bag or pouch. The bag may be of fibrous construction coated with a water impermeable protective material so as to retain the contents, such as is disclosed in European published Patent Application No. 0018678. Alternatively it may be formed of a water-insoluble synthetic polymeric material provided with an edge seal or closure designed to rupture in aqueous media as disclosed in European published Patent Application Nos. 0011500, 0011501, 0011502, and 0011968. A convenient form of water frangible closure comprises a water soluble adhesive disposed along and sealing one edge of a pouch formed of a water impermeable polymeric film such as polyethylene or polypropylene.

Examples

Abbreviations used in Examples

In the detergent compositions, the abbreviated component identifications have the following meanings:

STPP: : Sodium tripolyphosphate
Citrate: : Tri-sodium citrate dihydrate
Bicarbonate: : Sodium hydrogen carbonate
Citric Acid: : Anhydrous Citric acid
Carbonate: : Anhydrous sodium carbonate
Silicate: : Amorphous Sodium Silicate (SiO₂:Na₂O ratio = 1.6-3.2)
PB 1: : Anhydrous sodium perborate monohydrate
PB4: : Sodium perborate tetrahydrate of nominal formula NaBO₂.3H₂O.H₂O₂
Nonionic: : nonionic surfactant C ₁₃-C₁₅ mixed ethoxylated/ propoxylated fatty alcohol with an average degree of ethoxylation of 3.8 and an average degree of propoxylation of 4.5, sold under the tradename Plurafac by BASF
TAED: : Tetraacetyl ethylene diamine
HEDP: : Ethane 1-hydroxy-1,1-diphosphonic acid
DETPMP: : Diethyltriamine penta (methylene) phosphonate, marketed by monsanto under the tradename Dequest 2060
PAAC: : Pentaamine acetate cobalt (III) salt
Paraffin: : Paraffin oil sold under the tradename Winog 70 by Wintershall.
Protease: : Proteolytic enzyme
Amylase: : Amylolytic enzyme.
BTA: : Benzotriazole
PA30: : Polacrylic acid of average molecular weight approximately 4,500
Sulphate: : Anhydrous sodium sulphate.
PEG 4000: : Polyethylene Glycol molecular weight approximately 4000 available from Hoechst
PEG 8000: : Polyethylene Glycol molecular weight approximately 8000 available from Hoechst
Sugar: : Household sucrose
Gelatine: : Gelatine Type A, 65 bloom strength available from Sigma
Starch: : modified carboxy methyl cellulose sold under the tradename Nimcel available from metcaserle
Dodecandioic acid: : C12 dicarboxylic acid
Triacetin: : Glycerin triacetate sold under the tradename available from Eastman Corporation
Thixatrol: : Castor oil derivative sold under the tradename Thixatrol sold by Rheox
PVP: : Poly vinyl pyrrolidone having a molecular weight of 300,000
PEO: : Polyethylene oxide having a molecular weight of 45,000
pH: : Measured as a 1% solution in distilled water at 20°C

In the following examples all levels are quoted as % by weight of the compressed portion, the non-compressed portion or the coating layer:

Example 1

The compressed portion is prepared by delivering the composition of detergent components to a punch cavity of a modified 12 head rotary tablet press and compressing the composition at a pressure of 13KN/cm². The modified tablet press provides a tablet wherein the compressed portion has a mould. The non-compressed portion is poured into the mould of the compressed portion. For the purposes of Examples A to H the non-compressed portion comprises a gelling agent. Once the non-compressed portion has been delivered to the cavity the detergent tablet is subjected to a conditioning step, during which time the non-compressed portion hardens.

Example 2

The compressed portion is prepared by delivering the composition of detergent components to a punch cavity of a modified 12 head rotary tablet press and compressing the composition at a pressure of 13KN/cm². The modified tablet press provides tablet wherein the compressed portion has a mould. For the purposes of Examples I to K the non-compressed portion is in particulate form. The non-compressed portion is then poured into the mould of the compressed and coated with a coating layer. For the purposes of Example L to N the non-compressed portion comprises a binding agent. The non-compressed portion is poured into the mould of the compressed portion and then subjected to a conditioning step, during which time the non-compressed portion hardens.

Claims

A detergent tablet comprising a compressed portion and a non-compressed portion wherein:
a) the compressed portion comprises a pre-prepared depression or mould and dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein; and

b) the non-compressed portion comprises a finishing additive and is at least partially retained with the mould.
A detergent tablet comprising a compressed portion and a non-compressed portion comprising a finishing additive wherein the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein, and wherein the density of the non-compressed portion is at least 0.2 g/cm³ less than the density of the compressed portion.
A detergent tablet comprising a compressed portion and a non-compressed portion wherein:
a) the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein; and

b) the non-compressed portion comprises a finishing additive and is metasilicate-free.
A detergent tablet according to any of the preceding claims wherein the finishing additive is selected from the group consisting of organic polymeric compound, co-builder, enzyme, oxygen releasing bleach, bleach precursor or catalyst, surfactant, crystal growth inhibitor, bleach-destroying agent.
A detergent tablet according to any of the preceding claims wherein at least 60% of the compressed portion dissolves in deionised water at 50°C within 12 minutes.
A detergent tablet according to any of the preceding claims wherein at least 80% of the compressed portion dissolves in deionised water at 50°C within 12 minutes.
A detergent tablet according to any of the preceding claims wherein less than 40% of the non-compressed portion dissolves in deionised water at 50°C within 12 minutes.
A detergent tablet according to any of the preceding claims wherein less than 20% of the non-compressed portion dissolves in deionised water at 50°C within 12 minutes.
A detergent tablet according to any of the preceding claims wherein the non-compressed portion begins to dissolve after substantially all of the compressed portion has dissolved.
Use of a detergent tablet according to any of the preceding claims, in a washing machine having a washing cycle wherein at least 60% of the compressed portion dissolves within the first 12 minutes of the washing cycle and not more than 40% of the non-compressed portion dissolves in the washing cycle.
A detergent tablet comprising a compressed portion and a non-compressed portion wherein:
a) the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis measured using the SOTAX dissolution test method described herein; and

b) the non-compressed portion comprises a finishing additive which is a fabric softener or a rinse aid.
A detergent tablet according to claim 11 wherein the fabric softener is a cationic fabric softening agent.
A detergent tablet according to claim 11 wherein the rinse aid comprises a nonionic surfactant.
A method of washing laundry comprising treating soiled laundry with an aqueous wash solution in a laundry washing machine having dissolved or dispensed therein a detergent tablet according to any of claims 1 to 9, 11 or 12.
A method according to claim 14 wherein the finishing additive is a fabric softener and wherein the fabric softener is delivered into the rinsing cycle of the laundry washing machine after the clothes have been washed and softens the fabric.
A method of machine dishwashing soiled articles comprising treating the soiled articles with an aqueous liquid in a dishwashing machine having dissolved or dispensed therein a detergent tablet according to any of claims 1 to 9, 11 or 13.