EP1144585B1

EP1144585B1 - Detergent tablet

Info

Publication number: EP1144585B1
Application number: EP00908322A
Authority: EP
Inventors: Joanne Louise Whitaker; Eric Tcheou; Neil Joseph Lant; Christopher James Binder
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1999-01-23
Filing date: 2000-01-20
Publication date: 2005-03-30
Anticipated expiration: 2020-01-20
Also published as: DE60019084T2; EP1144585A1; CA2358872A1; AU2969100A; WO2000043488A1; JP4132678B2; CA2358872C; BR0007670A; DE60019084D1; AU771479B2; ATE292172T1; JP2002535449A; ES2240065T3

Abstract

A detergent tablet for use in a washing machine, the tablet having one or more phases at least one of which is in the form of a compressed particulate solid comprising: a) a polymeric disintegrant having a particle size distribution such that at least 90 % by weight thereof has a particle size below about 0.3 mm and at least 30 % by weight thereof has a particle size below about 0.2 mm; and b) a water-soluble hydrated salt having a melting point in the range from about 30 DEG C to about 95 DEG C. The detergent tablets display improved dissolution, strength and long-term storage characteristics.

Description

Technical Field

The present invention relates to detergent tablets. In particular, it relates to single and multi-phase detergent tablets having improved strength, especially on long-term storage, together with excellent dissolution characteristics.

Background

Detergent compositions in tablet form are known in the an. It is understood that detergent compositions in tablet form hold several advantages over detergent compositions in particulate from, such as ease of dosing, 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 any suitable equipment, preferably a tablet press. Tablets are typically formed by compression of the components of the detergent composition so that the tablets produced are sufficiently robust to be able to withstand handling and transportation without sustaining damage. In addition to being robust, tablets must also dissolve sufficiently fast so that the detergent components are released into the wash water as soon as possible at the beginning of the wash cycle.
However, a dichotomy exists in that as compression force is increased, the rate of dissolution of the tablets becomes slower. A low compression force, on the other hand, improves dissolution but at the expense of tablet strength. This problem is compounded by the fact that conventional tablet compositions have relatively poor long-term storage-stability characteristics and, to compensate, have to be manufactured to a higher compression specification. The present invention therefore seeks to provide tablet compositions having improved tablet dissolution characteristics and which at the same time delivers excellent tong-term storage-stability characteristics in terms of strength and robustness.
Polymeric disintegrants and water-soluble hydrated salts such as sodium acetate trihydrate are well-known components of tablet compositions. It has now been discovered, however, that mixtures of polymeric disintegrants of defined particle size distribution together with certain water-soluble hydrated salts are particularly beneficial for improving the dissolution behaviour of detergent tablets whilst at the same time providing excellent strength and robustness characteristics during long-term storage.
The present invention therefore provides single and multi-phase detergent tablets for use in automatic dishwashing, laundry, etc and which display improved dissolution, strength and long-term storage characteristics. Tablet compositions formulated for use in automatic dishwashing machines are particularly preferred herein.

Summary of the Invention

According to a first aspect of the invention, there is provided a detergent tablet for use in a washing machine, the tablet having one or more phases at least one of which is in the form of a compressed particulate solid comprising:
a) a polymeric disintegrant selected from starch, cellulose and derivatives thereof, alginates, sugars, polyvinylpyrrolidones, swellable clays and mixtures thereof having a particle size distribution such that at least 90 % by weight thereof has a particle size below 0.3mm and at least 30 % by weight thereof has a particle size below 0.2mm; and
b) a water-soluble hydrated salt having a solubility in distilled water of at least 25g/100g at 25°C, wherein the detergent tablets contain from 0.5% to 10% by weight of each of the polymeric disintegrant and water-soluble hydrated salt.
In preferred embodiments, the polymeric disintegrant has a particle size distribution such that at least 90 % by weight thereof has a particle size below 0.25mm and at least 50 % by weight thereof has a particle size below 0.2mm. Moreover, preferred disintegrants have a particle size distribution such that at least 90 % by weight thereof has a particle size above 0.05 mm, preferably above 0.075 mm.
In general terms, tablet disintegrating agents can be described as materials that enhance the rate of tablet dissolution in the wash liquor. Suitable polymeric disintegrants for use herein include polymers that swell on contact with water as well as those that facilitate water influx and/or efflux by forming channels in the detergent tablet. Certain polymeric disintegrating agents suitable for use herein can also act as tablet binders - in other words, they act to increase tablet strength as well as enhancing dissolution rate. Polymeric disintegrants for use herein include starch and cellulose and derivatives thereof, alginates, sugars, polyvinylpyrrolidones, swellable clays, and mixtures thereof. Examples of suitable disintegrating agent include starch and cellulose-based materials such as Arbocel (tradename), Vivapur (tradename) both available from Rettenmaier, Nymcel (tradename) available from Metsa-serla , burkeite, methyl cellulose, hydroxypropylcellulose, carboxymethylcellulose, cross-linked celluloses such as cross-linked carboxymethylcellulose (CMC), dextrans, cross-linked polyvinylpyrrolidones. Of these Vivapur and in particular Vivapur G200 (a microcrystalline cellulose having an average particle size of about 0.18mm) is particularly preferred from the viewpoint of providing both enhanced dissolution rate and tablet strength as well as excellent storage stability.
The water-soluble hydrated salt, on the the other hand, is preferably soluble to the extent of at least 40g/100g, more preferably at least 60g/100g of distilled water at 25°C. In addition, the water-soluble hydrated salt preferably has a melting point in the range from 30°C to 95°C, more preferably from 30°C to 75°C. Preferred water-soluble hydrated salts are selected from hydrates of sodium acetate, sodium metaborate, sodium orthophosphate, sodium dihydrogenphosphate, disodium hydrogen phosphate, sodium potassium tartrate, potassium aluminium sulphate, calcium bromide, calcium nitrate, sodium citrate, potassium citrate and mixtures thereof. Particularly suitable materials include sodium acetate trihydrate, sodium metaborate tetrahydrate or octahydrate, sodium orthophosphate dodecahydrate, sodium dihydrogen phosphate dihydrate, the di-, hepta- or dodecahydrate of disodium hydrogen phosphate, sodium potassium tartrate tetrahydrate, potassium aluminium sulphate dodecahydrate, calcium bromide hexahydrate, tripotassium citrate monohydrate, calcium nitrate tetrahydrate and sodium citrate dihydrate. In preferred embodiments, the water-soluble hydrated salt is selected from water-soluble mono-, di- tri- and tetrahydrate salts and mixtures thereof. Highly preferred herein is sodium acetate trihydrate, tripotassium citrate monohydrate, mixed alkali-metal citrates containing at least one potassium ion and mixtures thereof. Highly preferred are sodium acetate trihydrate and tripotassium citrate monohydrate.
In preparing the detergent tablets of the invention, the particulate solid comprising polymeric disintegrant and hydrated salt will normally be compressed at a pressure of at least 10kg/cm², preferably at least 40kg/cm², more preferably at least 250 kg/cm², and especially at least 350 kg/cm². In general, the detergent tablets of the invention contain from 0.5% to 10%, preferably from 0.8% to 5%, more preferably from 1% to 3% by weight of each of the polymeric disintegrant and water-soluble hydrated salt.
The detergent tablets of the invention include both single and multi-phase tablets. Multi-phase detergent tablets suitable herein will normally comprise a first phase in adhesive contact with one or more second phases (sometimes referred to herein as 'optional subsequent phases'). In preferred embodiments, the first phase is a compressed shaped body prepared at an applied compression pressure of at least 250 kg/cm², preferably at least 350 kg/cm² (3.43 kN/cm² or 34.3 MPa), more preferably from 400 to 2000 kg/cm², and especially from 600 to 1200 kg/cm² (compression pressure herein is the applied force divided by the cross-sectional area of the tablet in a plane transverse to the applied force - in effect, the transverse cross-sectional area of the die of the rotary press). The second phase, on the other hand, is preferably formed at a compression pressure of less than about 350 kg/cm², preferably in the range from 40 kg/cm² to 300 kg/cm² and more preferably from 70 to 270 kg/cm². In preferred embodiments, moreover, the first phase is formed by compression at a pressure greater than that applied to the second phase. In these embodiments, the compression pressures applied to the first and second phases will generally be in a ratio of at least 1.2:1, preferably at least 2:1, more preferably at least 4:1. The polymeric disintegrant and hydrated salt defined herein will normally be incorporated as part of the first phase although they can also be included in the second and optional subsequent phases.
Although simple multi-layer tablets are envisaged for use herein, preferred from the viewpoint of optimum product integrity, strength (measured for example by the Child Bite Strength [CBS] test) and dissolution characteristics are multi-phase tablets comprising a first phase in the form of a shaped body having at least one mould therein; and a second phase in the form of a particulate solid compressed within said mould. Such embodiments are sometimes referred to herein as 'mould' embodiments. The tablets of the invention, both mould embodiments and otherwise, will preferably have a CBS of at least about 6kg, preferably greater than about 8kg, more preferably greater than about 10kg, especially greater than about 12kg, and more especially greater than about 14kg, CBS being measured per the US Consumer Product Safety Commission Test Specification.
In the multi-phase embodiments of the invention, it is also preferred that the first and second phases herein are in a relatively high weight ratio to one another, for example at least 6:1, preferably at least 10:1; also that the tablet composition contain one or more detergent actives (for example enzymes, bleaches, bleach activators, bleach catalysts, surfactants, chelating agents etc) which is predominantly concentrated in the second phase, for example, at least 50%, preferably at least 60%, especially 80% by weight of the active (based on the total weight of the active in tablet) is in the second phase of the tablet. Again, such compositions are optimum for tablet strength, dissolution, cleaning, and pH regulation characteristics providing, for example, tablet compositions capable of dissolving in the wash liquor so as to deliver at least 50%, preferably at least 60%, and more preferably at least 80% by weight of the detergent active to the wash liquor within 10, 5, 4 or even 3 minutes of the start of the wash process.
The compositions herein are preferably include an effervescent agent, such agents being preferred in combination with polymeric disintegrant and water-soluble salt from the viewpoint of providing optimum tablet dissolution and strength characteristics.
Thus according to another embodiment of the invention the detergent tablet further comprises an effervescent agent.

Detailed Description of the Invention

It is an object of the present invention to provide a detergent tablet that is not only sufficiently robust to withstand handling and transportation, but also at least a significant portion of which dissolves rapidly in the wash water providing rapid delivery of detergent active. It is preferred that at least one phase of the tablet dissolves in the wash water within the first ten minutes, preferably five minutes, more preferably four minutes of the wash cycle of an automatic dishwashing or laundry washing machine. Preferably the washing machine is either an automatic dishwashing or laundry washing machine. The time within which the multi-phase tablet or a phase thereof or a detergent active component dissolves is determined according to DIN 44990 using a dishwashing machine available from Bosch on the normal 65°C washing program with water hardness at 18°H using a minimum of six replicates or a sufficient number to ensure reproducibility.
The detergent tablets of the present invention comprise a first phase and, in multi-phase tablet embodiments, also comprise a second and optional subsequent phases. The first phase is in the form of a shaped body of detergent composition comprising one or more detergent components as described below. Other than the hereindefined polymeric disintegrant and hydrated salt, preferred detergent components of the first phase include other builder components, bleach, enzymes, effervescent agents and surfactant. The components of the detergent composition are mixed together by, for example admixing dry components or spraying-on liquid components. The components are then formed into a first phase using any suitable compression equipment, but preferably in a tablet press.
In mould embodiments, the first phase is prepared such that it comprises at least one mould in the surface of the shaped body. In a preferred embodiment the mould is created using a specially designed tablet press wherein the surface of the punch that contacts the detergent composition is shaped such that when it contacts and presses the detergent composition it presses a mould, or multiple moulds into the first phase of the multi-phase detergent tablet. Preferably, the mould will have an inwardly concave or generally concave surface to provide improved adhesion to the second phase.
The tablets of the invention can also include one or more additional phases prepared from a composition or compositions which comprise one or more detergent components as described below. At least one phase (herein referred to as a second phase) preferably takes the form of a particulate solid (which term encompasses powders, granules, agglomerates, and other particulate solids including mixtures thereof with liquid binders, meltable solids, spray-ons, etc) compressed either as a layer or into/within the one or more moulds of the first phase of the detergent tablet such that the second phase itself takes the form of a shaped body. Preferred detergent components include builders, colourants, binders, surfactants, effervescent agents and enzymes, in particular amylase and protease enzymes. Suitable effervescing agents are those that produce a gas, especially oxygen, nitrogen dioxide or carbon dioxide, on contact with water. Examples of suitable effervescent agents include perborate, percarbonate, carbonate, bicarbonate in combination with inorganic acids such as sulphamic acid and/or carboxylic acids such as citric, malic and maleic acid and mixtures thereof.
The components of the detergent composition are mixed together by for example premixing dry components and admixing, preferably by spray-on, liquid components. The components of the second and optional subsequent phases are then compressed to form one or more layers or are fed into and retained within the mould provided by the first phase.
The preferred mould embodiments of the present invention comprises two phases; a first and a second phase. The first phase will normally comprise one mould and the second phase will normally consist of a single detergent active composition. However, it is envisaged that the first phase may comprise more than one mould and the second phase may be prepared from more than one detergent active composition. Furthermore, it is also envisaged that the second phase may comprise more than one detergent active composition contained within one mould. It is also envisaged that several detergent active compositions are contained in separate moulds. In this way potentially chemically sensitive detergent components can be separated in order to avoid any loss in performance caused by components reacting together and potentially becoming inactive or exhausted.
In a preferred aspect of the present invention the first, second and/or optional subsequent phases can additionally comprise a non-disintegrant binder, i.e., a material that increases tablet strength without increasing tablet dissolution rate. Preferred non-disintegrant binders are selected from polyethylene and/or polypropylene glycols, for example polyethylene and/or polypropylene glycols having an average molecular weight of from about 1000 to about 12000, especially those of molecular weight 4000, 6000 and 9000. The polyethyleneglycol non-disintegrant binders are highly preferred herein.
In a preferred aspect of the present invention the first phase weighs greater than 4g. More preferably the first phase weighs from 10g to 30g, even more preferably from 15g to 25g and most preferably form 18g to 24g. The second and optional subsequent phases weigh less than 4g. More preferably the second and/or optional subsequent phases weigh between 1g and 3.5g, most preferably from 1.3g to 2.5g.
The detergent tablets are prepared using any suitable tabletting equipment. Preferably multi-phase tablets herein are prepared by compression in a tablet press capable of preparing a tablet comprising a mould. In a particularly preferred embodiment of the present invention the first phase is prepared using a specially designed tablet press. The punch(es) of this tablet press are modified so that the surface of the punch that contacts the detergent composition has a convex surface.
A first detergent composition including the hereindefined polymeric disintegrant and hydrated salt, is delivered into the die of the tablet press and the punch is lowered to contact and then compress the detergent composition to form a first phase. The first detergent composition is compressed using an applied pressure of at least 250 kg/cm², preferably between 350 and 2000 kg/cm², more preferably 500 to 1500 kg/cm², most preferably 600 to 1200 kg/cm². The punch is then elevated, exposing the first phase containing a mould. A second and optional subsequent detergent composition(s) is then delivered into the mould. The specially designed tablet press punch is then lowered a second time to lightly compress the second and optional subsequent detergent composition(s) to form the second and optional subsequent phase(s). In another embodiment of the present invention where an optional subsequent phase is present the optional subsequent phase is prepared in a subsequent compression step substantially similar to the second compression step described above. The second and optional subsequent detergent composition(s) is compressed at a pressure of preferably less than 350 kg/cm², more preferably from 40 to 300 kg/cm², most preferably from 70 to 270 kg/cm². After compression of the second detergent composition, the punch is elevated a second time and the multi-phase detergent tablet is ejected from the tablet press. Single and multi-layer tablets without moulds can be prepared in a similar manner except using a tablet punch having a planar surface.
The detergent tablets of the invention are prepared by compression of one or more compositions comprising detergent active components. Suitably, the compositions may include a variety of different detergent components including builder compounds, surfactants, enzymes, bleaching agents, alkalinity sources, colourants, perfume, lime soap dispersants, organic polymeric compounds including polymeric dye transfer inhibiting agents, crystal growth inhibitors, heavy metal ion sequestrants, metal ion salts, enzyme stabilisers, corrosion inhibitors, suds suppressers, solvents, fabric softening agents, optical brighteners and hydrotropes. In the following, the proportions of these active components are given by weight of the corresponding composition of active detergent components, unless specified otherwise.
In multi-phase tablets, highly preferred detergent components of the first phase include a builder compound, a surfactant, an enzyme and a bleaching agent. Highly preferred detergent components of the second phase include builder, enzymes and disrupting agent.
Builders suitable for use herein include water-soluble builders such as citrates, carbonates and polyphosphates e.g. sodium tripolyphosphate and sodium tripolyphosphate hexahydrate; and partially water-soluble or insoluble builders such as crystalline layered silicates (EP-A-0164514 and EP-A-0293640) and aluminosilicates inclusive of Zeolites A, B, P, X, HS and MAP. The builder is typically present at a level of from about 1% to about 80% by weight, preferably from about 10% to about 70% by weight, most preferably from about 20% to about 60% by weight of composition.
Amorphous sodium silicates having an SiO₂:Na₂O ratio of from 1.8 to 3.0, preferably from 1.8 to 2.4, most preferably 2.0 can also be used herein although highly preferred from the viewpoint of long term storage stability are compositions containing less than about 22%, preferably less than about 15% total (amorphous and crystalline) silicate.
Surfactants suitable herein include anionic surfactants such as alkyl sulfates, alkyl ether sulfates, alkyl benzene sulfonates, alkyl glyceryl sulfonates, alkyl and alkenyl sulphonates, alkyl ethoxy carboxylates, N-acyl sarcosinates, N-acyl taurates and alkyl succinates and sulfosuccinates, wherein the alkyl, alkenyl or acyl moiety is C₅-C₂₀ , preferably C₁₀-C₁₈ linear or branched; cationic surfactants such as choline esters (US-A-4228042, US-A-4239660 and US-A-4260529) and mono C₆-C₁₆ N-alkyl or alkenyl ammonium surfactants wherein the remaining N positions are substituted by methyl, hydroxyethyl or hydroxypropyl groups; low and high cloud point nonionic surfactants and mixtures thereof including nonionic alkoxylated surfactants (especially ethoxylates derived from C₆-C₁₈ primary alcohols), ethoxylated-propoxylated alcohols (e.g., Olin Corporation's Poly-Tergent® SLF18), epoxy-capped poly(oxyalkylated) alcohols (e.g., Olin Corporation's Poly-Tergent® SLF18B - see WO-A-94/22800), ether-capped poly(oxyalkylated) alcohol surfactants, and block polyoxyethylene-polyoxypropylene polymeric compounds such as PLURONIC®, REVERSED PLURONIC®, and TETRONIC® by the BASF-Wyandotte Corp., Wyandotte, Michigan; amphoteric surfactants such as the amine oxides and alkyl amphocarboxylicc surfactants such as Miranol™ C2M; and zwitterionic surfactants such as the betaines and sultaines; and mixtures thereof. Surfactants suitable herein are disclosed, for example, in US-A-3,929,678 , US-A-4,259,217, EP-A-0414 549, WO-A-93/08876 and WO-A-93/08874. Surfactants are typically present at a level of from about 0.2% to about 30% by weight, more preferably from about 0.5% to about 10% by weight, most preferably from about 1 % to about 5% by weight of composition. In the preferred dishwashing aspect of the invention, the surfactant level is generally from about 1% to about 5% by weight of composition.
Enzymes suitable herein include bacterial and fungal cellulases such as Carezyme and Celluzyme (Novo Nordisk A/S); peroxidases; lipases such as Amano-P (Amano Pharmaceutical Co.), M1 Lipase^R and Lipomax^R (Gist-Brocades) and Lipolase^R and Lipolase Ultra^R (Novo); cutinases; proteases such as Esperase^R, Alcalase^R, Durazym^R and Savinase^R (Novo) and Maxatase^R, Maxacal^R, Properase^R and Maxapem^R (Gist-Brocades); and α and β amylases such as Purafect Ox Am^R (Genencor) and Termamyl^R, Ban^R, Fungamyl^R, Duramyl^R, and Natalase^R (Novo); and mixtures thereof. Enzymes are preferably added herein as prills, granulates, or cogranulates at levels typically in the range from about 0.0001 % to about 2% pure enzyme by weight of composition.
Bleaching agents suitable herein include chlorine and oxygen bleaches, especially inorganic perhydrate salts such as sodium perborate mono-and tetrahydrates and sodium percarbonate optionally coated to provide controlled rate of release (see, for example, GB-A-1466799 on sulfate/carbonate coatings), preformed organic peroxyacids and mixtures thereof with organic peroxyacid bleach precursors and/or transition metal-containing bleach catalysts (especially manganese or cobalt). Inorganic perhydrate salts are typically incorporated at levels in the range from about 1% to about 40% by weight, preferably from about 2% to about 30% by weight and more preferably from abut 5% to about 25% by weight of composition. Peroxyacid bleach precursors preferred for use herein include precursors of perbenzoic acid and substituted perbenzoic acid; cationic peroxyacid precursors; peracetic acid precursors such as TAED, sodium acetoxybenzene sulfonate and pentaacetylglucose; pemonanoic acid precursors such as sodium 3,5,5-trimethylhexanoyloxybenzene sulfonate (iso-NOBS) and sodium nonanoyloxybenzene sulfonate (NOBS); amide substituted alkyl peroxyacid precursors (EP-A-0170386); and benzoxazin peroxyacid precursors (EP-A-0332294 and EP-A-0482807). Bleach precursors are typically incorporated at levels in the range from about 0.5% to about 25%, preferably from about 1% to about 10% by weight of composition while the preformed organic peroxyacids themselves are typically incorporated at levels in the range from 0.5% to 25% by weight, more preferably from 1% to 10% by weight of composition. Bleach catalysts preferred for use herein include the manganese triazacyclononane and related complexes (US-A-4246612, US-A-5227084); Co, Cu, Mn and Fe bispyridylamine and related complexes (US-A-5114611); and pentamine acetate cobalt(III) and related complexes(US-A-4810410).
Other suitable components herein include organic polymers having dispersant, anti-redeposition, soil release or other detergency properties invention in levels of from about 0.1% to about 30%, preferably from about 0.5% to about 15%, most preferably from about 1% to about 10% by weight of composition. Preferred anti-redeposition polymers herein include acrylic acid containing polymers such as Sokalan PA30, PA20, PA15, PA10 and Sokalan CP10 (BASF GmbH), Acusol 45N, 480N, 460N (Rohm and Haas), acrylic acid/maleic acid copolymers such as Sokalan CP5 and acrylic/methacrylic copolymers. Preferred soil release polymers herein include alkyl and hydroxyalkyl celluloses (US-A-4,000,093), polyoxyethylenes, polyoxypropylenes and copolymers thereof, and nonionic and anionic polymers based on terephthalate esters of ethylene glycol, propylene glycol and mixtures thereof.
Heavy metal sequestrants and crystal growth inhibitors are suitable for use herein in levels generally from about 0.005% to about 20%, preferably from about 0.1% to about 10%, more preferably from about 0.25% to about 7.5% and most preferably from about 0.5% to about 5% by weight of composition, for example diethylenetriamine penta (methylene phosphonate), ethylenediamine tetra(methylene phosphonate) hexamethylenediamine tetra(methylene phosphonate), ethylene diphosphonate, hydroxy-ethylene-1,1-diphosphonate, nitrilotriacetate, ethylenediaminotetracetate, ethylenediamine-N,N'-disuccinate in their salt and free acid forms.
The compositions herein, especially for use in dishwashing, can contain a corrosion inhibitor such as organic silver coating agents in levels of from about 0.05% to about 10%, preferably from about 0.1% to about 5% by weight of composition (especially paraffins such as Winog 70 sold by Wintershall, Salzbergen, Germany), nitrogen-containing corrosion inhibitor compounds (for example benzotriazole and benzimadazole - see GB-A-1137741) and Mn(II) compounds, particularly Mn(II) salts of organic ligands in levels of from about 0.005% to about 5%, preferably from about 0.01% to about 1%, more preferably from about 0.02% to about 0.4% by weight of the composition.
Other suitable components herein include colourants, water-soluble bismuth compounds such as bismuth acetate and bismuth citrate at levels of from about 0.01 % to about 5%, enzyme stabilizers such as calcium ion, boric acid, propylene glycol and chlorine bleach scavengers at levels of from about 0.01% to about 6%, lime soap dispersants (see WO-A-93/08877), suds suppressors (see WO-93/08876 and EP-A-0705324), polymeric dye transfer inhibiting agents, optical brighteners, perfumes, fillers and clay and cationic fabric softeners.
Detergent components suitable for use herein are described in more detail in the Appendix to the Description (Ref: ADW I L)
The detergent tablets herein are preferably formulated to have a not unduly high pH, preferably a pH in 1% solution in distilled water of from about 8.0 to about 12.5, more preferably from about 9.0 to about 11.8, most preferably from about 9.5 to about 11.5.
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 the herein described compositions. By an effective amount 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.
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 the herein described compositions. By an effective amount 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.
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 EP-A-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 EP-A-0011500, EP-A-0011501, EP-A-0011502, and EP-A-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
Bicarbonate	Sodium hydrogen carbonate
Citric Acid	Anhydrous Citric acid
Carbonate	Anhydrous sodium carbonate
Citrate	Tripotassium citrate monohydrate
Silicate	Amorphous Sodium Silicate (SiO₂:Na₂O ratio = 2.0)
SKS-6	Crystalline layered silicate of formula δ-Na₂Si₂O₅
PB1	Anhydrous sodium perborate monohydrate
Nonionic	C₁₃ -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
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
Sulphate	Anhydrous sodium sulphate.
Triacetate	Sodium acetate trihydrate
Vivapur G200	Microcrystalline cellulose having average particle size of 0.18mm
PEG 400	Polyethylene Glycol molecular weight approximately 400 available from Hoechst
PEG 4000	Polyethylene Glycol molecular weight approximately 4000 available from Hoechst

In the following examples all levels are quoted as parts by weight:

Examples I-VI

The following illustrates detergent tablets of the present invention suitable for use in a dishwashing machine.

	I	II	III	IV	V	VI
Phase 1
STPP		9.6				11.5
Silicate	1.7	0.67	1.6	1.0	1.0	2.4
SKS-6	2.5	1.5		2.3	2.25
Carbonate	5.00	2.74	3.5	3.59	4.10	5.25
HEDP	0.25	0.18	0.18	0.28	0.28	0.28
PB1	3.5	2.45	2.45	3.68	3.68	3.68
PAAC	0.002	0.002	0.002	0.003	0.004	0.004
Triacetate	0.5	0.6	0.5	0.4	0.8	0.5
Vivapur G200	0.75	0.7	0.65	0.8	0.4	0.75
Amylase	0.148	0.110	0.110	0.252	0.163	0.163
Protease	0.06	0.06	0.06	0.09	0.09	0.09
Nonionic	0.90	0.80	0.80	1.20	1.20	1.20
PEG 4000	0.4	0.26	0.26	0.38	0.39	0.39
BTA	0.01	0.04	0.04		0.06	0.06
Paraffin	0.16	0.10	0.10	0.15	0.15	0.15
Perfume	0.02	0.02	0.02	0.013	0.013	0.013
Sulphate				0.502	0.05	2.843
Total	15.9g	19.83g	10.27g	14.64g	14.63g	29.3g
Phase 2
Amylase	0.30	0.35	0.25	0.30	0.35	0.25
Protease	0.25	0.22	0.30	0.25	0.22	0.30
Citric acid	0.3		0.30	0.3		0.30
Sulphamic acid		0.3			0.3
Bicarbonate	0.92	0.45	0.45	1.09	0.45	0.45
Carbonate		0.55			0.55
Silicate			0.64			0.64
CaCl₂		0.07			0.07
PEG 400	0.15
PEG 4000	0.08	0.06	0.06	0.06	0.06	0.06
Total	2.0g	2.0g	2.0g	2.0g	2.0g	2.0g

The tablet compositions are prepared as follows. The detergent active composition of phase 1 is prepared by admixing the granular and liquid components and is then passed into the die of a conventional rotary press. The press includes a punch suitably shaped for forming a mould. The cross-section of the die is approximately 30x38 mm. The composition is then subjected to a compression force of 940 kg/cm² and the punch is then elevated exposing the first phase of the tablet containing the mould in its upper surface. The detergent active composition of phase 2 is prepared in similar manner and is passed into the die. The particulate active composition is then subjected to a compression force of 170 kg/cm², the punch is elevated, and the multi-phase tablet ejected from the tablet press. The resulting tablets display improved dissolution, strength and long-term storage characteristics.

Examples VII-XII

The following illustrates further detergent tablets of the present invention suitable for use in a dishwashing machine.

	VII	VIII	IX	X	XI	XII
Phase 1
STPP		9.6				11.5
Silicate	1.7	0.67	1.6	1.0	1.0	2.4
SKS-6	2.5	1.5		2.3	2.25
Carbonate	5.00	2.74	3.5	3.59	4.10	5.25
HEDP	0.25	0.18	0.18	0.28	0.28	0.28
PB1	3.5	2.45	2.45	3.68	3.68	3.68
PAAC	0.002	0.002	0.002	0.003	0.004	0.004
Citrate	0.5	0.6	0.5	0.4	0.8	0.5
Vivapur G200	0.75	0.7	0.65	0.8	0.4	0.75
Amylase	0.148	0.110	0.110	0.252	0.163	0.163
Protease	0.06	0.06	0.06	0.09	0.09	0.09
Nonionic	0.90	0.80	0.80	1.20	1.20	1.20
PEG 4000	0.4	0.26	0.26	0.38	0.39	0.39
BTA	0.01	0.04	0.04		0.06	0.06
Paraffin	0.16	0.10	0.10	0.15	0.15	0.15
Perfume	0.02	0.02	0.02	0.013	0.013	0.013
Sulphate				0.502	0.05	2.843
Total	15.9g	19.83g	10.27g	14.64g	14.63g	29.3g
Phase 2
Amylase	0.30	0.35	0.25	0.30	0.35	0.25
Protease	0.25	0.22	0.30	0.25	0.22	0.30
Citric acid	0.3		0.30	0.3		0.30
Sulphamic acid		0.3			0.3
Bicarbonate	0.92	0.45	0.45	1.09	0.45	0.45
Carbonate		0.55			0.55
Silicate			0.64			0.64
CaCl₂		0.07			0.07
PEG 400	0.15
PEG 4000	0.08	0.06	0.06	0.06	0.06	0.06
Total	2.0g	2.0g	2.0g	2.0g	2.0g	2.0g

The tablet compositions are prepared as those in examples I to VI. The resulting tablets display improved dissolution, strength and long-term storage characteristics.

Claims

A detergent tablet for use in a washing machine, the tablet having one or more phases at least one of which is in the form of a compressed particulate solid comprising:

a) a polymeric disintegrant selected from starch, cellulose and derivatives thereof, alginates, sugars, polyvinylpyrrolidones, swellable clays and mixtures thereof having a particle size distribution such that at least 90 % by weight thereof has a particle size below 0.3mm and at least 30 % by weight thereof has a particle size below 0.2mm; and

b) a water-soluble hydrated salt having a solubility in distilled water of at least 25g/100g at 25°C, wherein the detergent tablets contain from 0.5% to 10% by weight of each of the polymeric disintegrant and water-soluble hydrated salt.
A detergent tablet according to claim 1 wherein the polymeric disintegrant has a particle size distribution such that at least 90 % by weight thereof has a particle size below 0.25mm and at least 50 % by weight thereof has a particle size below 0.2mm.
A detergent tablet according to claim 1 or 2 wherein the polymeric disintegrant has a particle size distribution such that at least 90 % by weight thereof has a particle size above 0.05mm, preferably above 0.075mm.
A detergent tablet according to any of claims 1 to 3 further comprising an effervescent agent.
A detergent tablet according to any of claims 1 to 4 wherein the water-soluble hydrated salt is selected from hydrates of sodium acetate, sodium metaborate, sodium orthophosphate; sodium dihydrogenphosphate, disodium hydrogen phosphate, sodium potassium tartrate, potassium aluminium sulphate, calcium bromide, calcium nitrate, sodium citrate, potassium citrate and mixtures thereof.
A detergent tablet according to any of claims 1 to 5 wherein the water-soluble hydrated salt is selected from water-soluble mono-, di- tri- and tetrahydrate salts and mixtures thereof.
detergent tablet according to any of claims 1 to 6 wherein the water-soluble hydrated salt has a melting point in the range from 30°C to 95°C.
A detergent tablet according to any of claims 1 to 7 wherein the water-soluble hydrated salt has a melting point in the range from 30°C to 75°C.
A detergent tablet according to any of claims 1 to 8 containing from 0.5% to 10% by weight each of the polymeric disintegrant and water-soluble hydrated salt.
A detergent tablet according to any of claims 1 to 9 having a child bite strength (CBS) of at least 6 kg, preferably greater than 14 kg.
A detergent tablet according to any of claims 1 to 10 wherein the particulate solid compressed at a pressure of at least 40 kg/cm², preferably at least 250 kg/cm². more preferably at least 350 kg/cm².
A detergent tablet according to any of claims 1 to 11, the detergent tablet comprising

a) a first phase in the form of a shaped body having at least one mould therein; and

b) a second phase is in the form of a particulate solid compressed within said mould.
A detergent tablet according to any of claim 12 wherein the second phase is compressed at a pressure of less than 350 kg/cm².
A detergent tablet according to claim 11 or 13 wherein the first phase is compressed at a pressure of at least 350 kg/cm².