EP1144567B1

EP1144567B1 - Detergent tablet

Info

Publication number: EP1144567B1
Application number: EP99933807A
Authority: EP
Inventors: Christopher James Binder
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1998-07-17
Filing date: 1999-07-09
Publication date: 2004-09-22
Anticipated expiration: 2019-07-09
Also published as: DE69920517D1; ES2224681T3; CA2337401C; CA2337401A1; AU4978599A; BR9912150A; JP2002520475A; ATE277166T1; TR200100095T2; WO2000004116A2; EP1144567A2; HK1041899A1; WO2000004116A3; DE69920517T2; EP1144567A3

Abstract

A multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in adhesive contact with one or more second phases, at least one second phase being in the form of a compressed particulate solid incorporating liquid adhesive and having an average porosity of less than about 0.15 ml/g. The liquid adhesive is preferably selected from polyethylene glycols having an average molecular weight in the range from about 200 to about 700 and is preferably applied by post-addition to the particulate solid prior to compression. The multi-phase tablets provide improved interphase adhesivity, robustness and strength together with excellent dissolution and cleaning characteristics.

Description

Technical Field

The present invention relates to multi-phase detergent tablets. In particular, it relates to multi-phase detergent tablets having improved robustness and product integrity together with excellent dissolution characteristics.

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 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. The present invention therefore seeks to find a balance between tablet robustness and tablet dissolution.

Solutions to this problem, as seen in the prior art, have included compressing the tablets with low compression pressure. However tablets made in this way, although having a fast relative dissolution rate, tend to crumble, becoming damaged and unacceptable to the consumer. Other solutions have included preparing tablets using a high relative compression pressure, in order to achieve the required level of robustness, and comprising a dissolution aid, such as an effervescent agent.

Multi-phase detergent tablets described in the prior art are prepared by compressing a first composition in a tablet press to form a substantially planar first layer. A further detergent composition is then delivered to the tablet press on top of the first layer. This second composition is then compressed to form another substantially planar second layer. Thus the first layer is generally subjected to more than one compression as it is also compressed during the compression of the second composition. Typically the first and second compression forces are in the same order of magnitude. The Applicant has found that where this is the case, because the compression force must be sufficient to bind the first and second compositions together, the force used in both the first and second compression steps must be in the range of from about 4,000 to about 20,000 kg (assuming a tablet cross-section of about 10 cm²). A consequence of this is a slower rate of tablet dissolution. Other multi-phase tablets exhibiting differential dissolution are prepared such that the second layer is compressed at a lower force than the first layer. However, although the dissolution rate of the second layer is improved, the second layer is soft in comparison to the first layer and is therefore vulnerable to damage caused by handling and transportation. Moreover, the two layers are found to have poor adhesion characteristics and can break up under the relatively mild stress conditions found in storage or transportation.

GB-A-2,320,254 discloses a tablet prepared by selecting from a base particle mixture a low porosity portion, adding to this portion a liquid non-ionic surfactant or hydrocarbon oil, mixing the resulting treated particles with the rest of the particles and tabletting the whole.

EP 481,547 A1 discloses a multi-phase detergent tablet comprising an inner layer, a barrier layer and an outer layer. The tablet releases sequentially ingredients contained in the outer layer and ingredients contained in the inner layer.

The present invention therefore provides multi-phase detergent tablets for use in automatic dishwashing, laundry, and which have improved integrity and robustness together with excellent dissolution characteristics.

Summary of the Invention

According to a first aspect of the invention, there is provided a multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in the form of a shaped body having at least one mould in the surface thereof wherein the first phase is in adhesive contact with one or more second phases contained within the mould, at least one second phase being in the form of a compressed particulate solid incorporating adhesive which is liquid a 28°C and having an average porosity of less than 0.15 ml/g, preferably less than 0.13 ml/g and more preferably less than 0.11 ml/g as measured by mercury porosimetry.

Porosity can be measured by known methods including image analysis, mercury porosimetry, determination and comparison of volume and mass, determination and comparison of surface area and diameter, gas chromatography, x-ray small angle scattering and displacement methods. The method of measuring porosity used herein is the mercury porosimetry method, average porosity being defined as the total intrusion volume of the particulate solid (prior to introduction of the liquid adhesive) for pore volumes below 30µm. Preferably, the compressed particulate solid has an average porosity of less than 0.09 ml/g, more preferably less than 0.07 ml/g and especially less than 0.05 ml/g.

The adhesive is liquid at or close to ambient temperatures (28°C, more preferably 25°C and above). It is also preferred herein to use adhesives that are water-frangible or water-sensitive, for example, adhesives based on water-soluble or water-emulsifiable polymers. It will also be understood that water and other solvent-based adhesives, for example, adhesives comprising aqueous polymeric solutions or emulsions, are also suitable for use herein. However, the preferred adhesives are either water-free or are used in conjunction with a water-sink (for example, anhydrous builder salts) in order to minimise the free moisture content of the final tablet compositions which is preferably less than about 1% by weight. The liquid adhesive is incorporated by post-addition, preferably as a spray-on, to the particulate solid prior to compression. The level of liquid adhesive is preferably from 0.1% to 3%, more preferably from 0.5% to 1.5% by weight of the second phase particulate solid.

In preferred embodiments, the first phase also takes the form of a compressed particulate solid, the average porosity of which is greater than that of the second phase particulate solid by at least 10%, preferably at least 30%, and more preferably at least 60%, this being valuable for optimum adhesion. In general, the average porosity of the first phase is at least 0.1 ml/g, preferably at least 0.12 ml/g, more preferably at least 0.14 ml/g, especially at least 0.16 ml/g and more especially at least 0.18 ml/g as measured by mercury porosimetry.

Preferred adhesives for use herein are selected from water-soluble poly(C₂-C₄)-alkylene oxide polymers and copolymers, poly(C₂-C₄)-alkoxylated nonionic surfactants, aqueous polymeric solutions and emulsions, and mixtures thereof. Of these, highly preferred from the viewpoint of optimum product integrity, robustness and dissolution characteristics are the polyethylene glycols having an average molecular weight in the range from 200 to 700, preferably from 250 to 600, although polyethylene glycols of a somewhat higher average molecular weight, for example up to 900, can be used if the detergent tablet is prepared at a temperature slightly above ambient, for example up to 28°C.

Thus according to second aspect of the invention, there is provided a multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in the form of a shaped body having at least one mould in the surface thereof wherein the first phase is in adhesive contact with one or more second phases contained within the mould, at least one second phase being in the form of a compressed particulate solid incorporating liquid adhesive selected from polyethylene glycols having an average molecular weight in the range from 200 to 700.

The detergent tablets herein comprise at least one 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 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.

Preferred herein from the viewpoint of providing optimum interphase adhesivity and robustness are tablets and processes wherein the liquid adhesive is incorporated by post-addition to the particulate solid of the second phase prior to compression thereof. Post-addition preferably takes the form of a spray-on of the liquid adhesive to the particulate solid and normally will take place as a final step shortly before compression, preferably within 1 day, and more preferably within 12 hours.

Thus, according to a further aspect of the invention, there is provided a multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in the form of a shaped body having at least one mould in the surface thereof wherein the first phase is in adhesive contact with one or more second phases, at least one second phase contained within the mould being in the form of a compressed particulate solid incorporating adhesive which is liquid at 28°C and wherein the liquid adhesive is incorporated by post-addition, preferably as a spray-on, to the particulate solid prior to compression.

From the viewpoint of optimum product integrity, strength (measured for example by the Child Bite Strength [CBS] test) and dissolution characteristics are tablets wherein the first phase is in the form of a shaped body having at least one mould therein; and the second phase is 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 will preferably have a CBS of at least 8kg, preferably greater than 10kg, more preferably greater than 12kg, and especially greater than 14kg, CBS being measured per the US Consumer Product Safety Commission Test Specification.

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 about 6:1, preferably at least about 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.

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 multi-phase detergent tablet of the present invention comprises a first phase, 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. Preferred detergent components include, builder, bleach, enzymes 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 equipment, but preferably by compression, for example in a tablet press. Alternatively, the first phase can be prepared by extrusion, casting.

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 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) compressed 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, disrupting agents and enzymes, in particular amylase and protease enzymes. In another preferred aspect of the present invention the second and optional subsequent phases comprise a disrupting agent that may be selected from either a disintegrating agent or an effervescent agent. Suitable disintegrating agents include agents that swell on contact with water or facilitate water influx and/or efflux by forming channels in the detergent tablet. 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 such as Arbocel (tradename), Vivapur (tradename) both available from Rettenmaier, Nymcel (tradename) available from Metsa-serla , alginates, acetate trihydrate, burkeite, monohydrated carbonate formula Na₂CO₃.H₂O, hydrated STPP with a phase I content of at least about 40%, 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 effervescent agents may be selected from the group consisting of 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, the adhesive and other 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 tablets of the present invention comprises two phases; a first and a second phase. The first phase will 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 may comprise a binder. Where present the binder is selected from the group consisting of organic polymers, for example polyethylene and/or polypropylene glycols having an average molecular weight of from 1000 to 12000, especially those of molecular weight 4000, 6000 and 9000, polyvinyl pyrolindone (PVP), especially PVP of molecular weight 90 000, polyacrylates, sugars and sugar derivatives, starch and starch derivatives, for example hydroxy propyl methyl cellulose (HPMC) and carboxy methyl cellulose (CMC); and inorganic polymers, such as hexametaphosphate. The polyethyleneglycol binders are highly preferred herein. The combination of liquid adhesive and binder is particularly valuable from the viewpoint of providing improved interphase adhesivity and robustness.

In a preferred aspect of the present invention the first phase weighs greater than 5g. 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 components of the second and optional subsequent phases are compressed, at a much lower compression force relative to the compression force normally used to prepare high strength tablets. At the same time, the tablets of the invention display excellent adherence between phases and product integrity. Thus an advantage of the present invention is that because a lower compression force is used heat, force or chemically sensitive detergent components can be incorporated into the detergent tablet without sustaining the consequential loss in performance usually encountered when incorporating such components into tablets.

Yet another advantage of the present invention is the ability to prepare a multi-phase detergent tablet wherein one phase can be designed to dissolve, preferably significantly before another phase. In the present invention it is preferred that the second and optional subsequent phase(s) dissolves before the first phase. According to the preferred weight ranges described above, it preferable that the first phase dissolves in from 5 to 20 minutes, more preferably from 10 to 15 minutes and the second and/or optional subsequent phases dissolve in less than 5 minutes, more preferably less than 4.5 minutes, most preferably less than 4 minutes. The time in which the first, second and/or optional subsequent phase dissolve are independent from each other. Thus in a particularly preferred aspect of the present invention differential dissolution of the phases is achieved. A particular benefit of being able to achieve differential dissolution of the multi-phase detergent tablet is that a component that is chemically inactivated by the presence of another component can be separated into a different phase. In this case the component that is inactivated is preferably located in the second and optional subsequent phase(s).

The multi-phase detergent tablets are prepared using any suitable tabletting equipment. Preferably the tablets 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 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 an optional 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. Multi-layer tablets without moulds can be prepared in a similar manner except using a tablet punch having a planar surface.

The first and second and or optional subsequent phases of the multi-phase detergent tablet described herein are prepared by compression of one or more compositions comprising detergent active components. Suitably, the compositions used in any of these phases 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 suppressors, 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.

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 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.

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.

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.

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
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.
PEG 400 :: Polyethylene Glycol average molecular weight approximately 400 available from Hoechst
PEG 4000 :: Polyethylene Glycol average molecular weight approximately 4000 available from Hoechst

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

Examples I-IV

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

	I	II	III	IV	V	VI
Phase I
STPP	9.62	9.62	10.45	9.57	9.57	11.47
Silicate	0.50	0.67	1.60	1.00	1.00	2.40
SKS-6	1.5	1.50	1.5	2.30	2.25
Carbonate	2.33	2.74	3.5	3.59	4.10	5.25
HEDP	0.18	0.18	0.18	0.28	0.28	0.28
PB1	2.45	2.45	2.45	3.68	3.68	3.68
PAAC	0.002	0.002	0.002	0.003	0.004	0.004
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	0.40	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	0.04	0.04	0.04		0.06	0.06
Paraffin	0.10	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	17.75g	18.55g	21.07g	23.0g	23.0g	23.0g
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		0.20	0.3		0.30
Sulphamic acid		0.3			0.3
Bicarbonate	1.09	0.45	0.56	1.09	0.45	0.45
Carbonate		0.55			0.55
Silicate						0.64
CaCl₂		0.07			0.07
PEG 4000	0.045	0.042	0.075	0.045	0.04	0.045
PEG 400	0.015	0.018	0.015	0.015	0.02	0.015
Total	2.0g	2.0g	1.4g	2.0g	2.0g	2.0g

The multi-phase 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 phase 1 particulate compositions have a mean particle size of from about 520-570µm, with about 5% passing a 150µm sieve and about 30% passing a 250µm sieve. The rotary press includes a punch suitably shaped for forming the mould. The cross-section of the die is approximately 30x38 mm. The composition is then subjected to 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, except that the liquid adhesive, PEG 400, is added as a final step by spray-on onto the particulate mixture, and the composition is then passed into the die. The phase 2 particulate compositions have a mean particle size of from about 430-470µm, with about 5% passing a 150µm sieve and about 35% passing a 250µm sieve. 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 dissolve or disintegrate in a washing machine as described above within 12 minutes, phase 2 of the tablets dissolving within 5 minutes. The tablets provide excellent dissolution and cleaning characteristics together with good tablet integrity, inter-phase adhesion and strength.

Claims

A multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in the form of a shaped body having at least one mould in the surface thereof wherein the first phase is in adhesive contact with one or more second phases, at least one second phase contained within the mould being in the form of a compressed particulate solid incorporating adhesive which is liquid at 28°C and having an average porosity of less than 0.15 ml/g as measured by mercury porosimetry.
A multi-phase detergent tablet according to claim 1 wherein the adhesive is liquid at 25°C and above and is selected from the group consisting of water-soluble poly(C₂-C₄)-alkylene oxide polymers and copolymers, poly(C₂-C₄)-alkoxylated nonionic surfactants, aqueous polymeric solutions and emulsions, and mixtures thereof.
A multi-phase detergent tablet according to claim 1 or 2 wherein the adhesive is selected from polyethylene glycols having an average molecular weight in the range from 200 to 700.
A multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in the form of a shaped body having at least one mould in the surface thereof wherein the first phase is in adhesive contact with one or more second phases, at least one second phase contained within the mould being in the form of a compressed particulate solid incorporating adhesive which is liquid at 28°C selected from polyethylene glycols having an average molecular weight in the range from 200 to 700.
A multi-phase detergent tablet according to any of claims 1 to 4 wherein the first and/or second phases additionally comprises a binder selected from the group consisting of sugar and sugar derivatives, starch and starch derivatives, inorganic and organic polymers.
A multi-phase detergent tablet according to claim 5 wherein the binder is selected from polyethylene glycols having an average molecular weight in the range from 1000 to 12000.
A multi-phase detergent tablet according to any of claims 1 to 4 wherein the liquid adhesive is incorporated by post-addition, preferably as a spray-on, to the particulate solid prior to compression.
A multi-phase detergent tablet for use in a washing machine, the tablet comprising a first phase in the form of a shaped body having at least one mould in the surface thereof wherein the first phase is in adhesive contact with one or more second phases, at least one second phase contained within the mould being in the form of a compressed particulate solid incorporating adhesive which is liquid at 28°C and wherein the liquid adhesive is incorporated by post-addition, preferably as a spray-on, to the particulate solid prior to compression.
A multi-phase detergent tablet according to any of claims 1 to 6 wherein the first phase is in the form of a shaped body formed by compression at a pressure greater than that of the second phase.
A multi-phase detergent tablet according to any of claims 1 to 7 wherein the second phase is compressed at a pressure of less than 350 kg/cm².
A multi-phase detergent tablet according to any of claims 1 to 8 wherein the first phase is compressed at a pressure of at least 350 kg/cm².
A multi-phase detergent tablet according to any of claims 1 to 9 wherein

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

b) the second phase is in the form of a particulate solid compressed within said mould.
A multi-phase detergent tablet according to any of claims 1 to 10 wherein the second phase additionally comprises a disrupting agent.