WO2009092699A1

WO2009092699A1 - Machine dishwash detergent compositions

Info

Publication number: WO2009092699A1
Application number: PCT/EP2009/050575
Authority: WO
Inventors: Huig Euser; Jean-Paul Janssens; Robert Jan Moll; Sachindew Manodjkoemar Ramcharan
Original assignee: Unilever Nv; Unilever Plc; Hindustan Unilever Limited
Priority date: 2008-01-24
Filing date: 2009-01-20
Publication date: 2009-07-30
Also published as: PT2245129E; UA103760C2; EP2245129B1; BRPI0906743A2; EP2245129A1; PL2245129T3; ATE557079T1; EA201001199A1

Abstract

The present invention provides a machine dishwash detergent composition,which is substantially free of phosphate, and comprises an amino polycarboxylic compound selected from methylglycine diacetic acid (MGDA) and iminodiacetic acid (IDS), in an amount of at least 25 wt%, preferably between 25 and 70 wt%, and a bleaching agent comprising percarbonate, the amount of percarbonate being in the range of 3 to 12 wt% based on total weight of the composition. Preferably, the composition comprises MGDA, and 2 to 7 wt% silicates.

Description

MACHINE DISHWASH DETERGENT COMPOSITIONS

Technical field of the invention

The present invention is in the field of machine dishwashing. More specifically, the invention encompasses automatic dishwashing detergents and their use in a dish washing process.

Background to the invention

Traditionally, a consumer would use three products to wash dishes in an automatic dishwashing machine. Salt would be added to the salt compartment to soften water. A dishwashing detergent composition would serve to clean the articles, and a rinse aid would be used in the final steps of the dishwashing process to avoid streaks and smears on the articles.

In recent years these traditional products have at least partly been replaced by products that are referred to as "2 in 1" products and "3 in 1" products.

"2 in 1" products already comprise the salt-function built into the product and therefore in use, there is no longer a need to add salt to the salt compartment of the washing machine. A rinse aid is still separately added.

"3 in 1" products obviate the need for salt addition and rinse aid addition. The three desired functions of cleaning, rinsing and softening are included in one product.

Other multifunctional products have been developed in recent years, such as 4-in-l and 5-in-l detergent products have been developed, i.e. with glass protection functionality and/or water-soluble wraps. All these products are further referred to as multifunctional compositions .

This product shift has greatly improved the ease of handling for consumers .

Currently most commercial multifunctional products comprise a builder. A builder generally serves to improve and extend the action of surfactant. A builder may provide this contribution in a number of ways, e.g. by binding of calcium and magnesium ions, binding of transition metal ions, peptisation and suspension of soil in solution, provision of alkalinity and structuring/solubilising powder. It also can contribute in the prevention of non-optimal functioning of surfactants. The binding of calcium and magnesium is the most relevant function among these. The builder system is preferably water-soluble.

The most widely known builder is sodium tripolyphosphate . A well known draw back of this builder is that it contains phosphorus. Many attempts have been made to (partly) replace this builder with one that is more environmentally friendly but still shows the desired functionality.

Examples of suitable replacers that have been suggested are carbonate, citrate, zeolite, silicate and amino polycarboxylic compounds such as methylglycine diacetic acid (MGDA) and variants thereof e.g. NTA (nitrile triacetic acid), GDA (glutamic diacetic acid) , DPA (dipicolinic acid) and IDS (imino disuccinic acid) . Although these may be suitable in general in a variety of products to (partly) replace phosphate, some of them have drawbacks when used in multifunctional compositions. The use of amino polycarboxylate compounds such as methylglycine diacetic acid in detergent compositions is known from the prior art, e.g. US 6,162,259, US 6,172,036, US 6,376,449, US 6,159,922, US 6,770,616.

Although the replacement of phosphate builder by polycarboxylic compounds provides environmental benefits, this replacement is not yet commonly applied as polycarboxylic compounds, such as methylglycine diacetic acid (MGDA) and iminodiacetic acid (IDS), are known to show several drawbacks.

MGDA, and also IDS, is known to be a chelating agent which, however, has disadvantages connected to its inherent hygroscopicity which is why this product is usually available as a liquid. Such is a serious drawback for the production of multifunctional products, which in most cases are at least partially in the form of a powder or tablet. This significantly reduces the applicability of this product.

Furthermore, a negative effect on metal corrosion was observed when MGDA was applied in machine dishwash compositions.

The use of one or more bleaching agents in machine dishwash detergent is commonly known. These components are in particular applied for their cleaning performance. Examples of commonly applied bleaching agents are monopersulphate, perborate monohydrate, perborate tetrahydrate, and percarbonate . These days, legislation around the use of perborate has led to the general application of percarbonate as the main bleaching agent in machine dishwash compositions. In order to arrive at the desired performance of cleaning, percarbonate is usually applied in amounts of 15-20 wt%. The use of lower amounts is commonly known to result in undesired reduced cleaning performance .

However, the use of MGDA or IDS as a detergency builder in a percarbonate containing dishwash composition was found to lead to increased dissociation of the percarbonate. As a result, reduced stability of the detergent product leading to reduced performance when such product is used to clean the dishware was observed. Furthermore, the temperature increase observed is associated with the increased dissociation of the percarbonate, which provides serious drawbacks at production, storage and transportation of the dishwash composition.

It is an object of the invention to provide a machine dishwash composition in which substantially no phosphate is used, in which at least an amino polycarboxylate compound, preferably MGDA, is used and which does not show the negative effects associated with use of such a compound. An object of the current invention is to provide a machine dishwash detergent composition comprising amino polycarboxylate compounds selected from MGDA and IDS, and preferably MGDA, as detergency builder and percarbonate, the composition having a good stability both on production and storage, and the composition having a good cleaning performance.

Another object of the current invention is to provide a machine dishwash detergent composition which is substantially free of phosphate, and comprises amino polycarboxylate compounds selected from MGDA and IDS, and preferably MGDA, and percarbonate which shows a further improved stability of said composition and which provides some protection for metal corrosion .

It is a further object of the current invention to provide a machine dishwash detergent composition which is substantially free of phosphate, and comprises an amino polycarboxylate compounds selected from MGDA and IDS, and preferably MGDA, and percarbonate, which composition shows good flow properties of a powdered mix of the composition during the manufacturing process, and also improved rinse efficiency performance.

SUMMARY OF THE INVENTION

In a first aspect the invention provides a machine dishwash detergent composition which is substantially free of phosphate, and comprises an amino polycarboxylic compound selected from methylglycine diacetic acid (MGDA) and iminodiacetic acid (IDS), in an amount of at least 25 wt%, preferably between 25 and 70 wt%, and a bleaching agent comprising percarbonate, the percarbonate amount being in the range of 3 to 12 wt% based on total weight of the composition. Preferably the amino polycarboxylic compound comprises methylglycine diacetic acid and/or its corresponding salts.

In a second aspect of the invention a method for cleaning dishware in a mechanical dishwashing machine is provided, comprising treating the dishware with a wash liquor comprising a dishwashing composition of the invention.

In a third aspect, the invention relates to the use of a dishwashing composition according to the invention for use in an automatic dishwashing machine, such that no salt is required for the rejuvenation of ion exchange material within the machine .

DETAILED DESCRIPTION OF THE INVENTION Definitions

Weight percentages (indicated as ^λwt%' ) herein are calculated based upon total weight of the composition, unless indicated otherwise.

In the context of this invention, Substantially free of means a maximum concentration of the compound concerned of 1 wt% based on the weight of the detergent composition.

At the instances in this specification where reference is made to amino polycarboxylic acids, the corresponding salts are meant to be included as well.

The amounts mentioned in this specification are based on the recommended amount of detergent composition used per main wash cycle. Machine dishwash detergent compositions according to the invention may suitably be dosed in the wash liquor at levels of from 2 g/1 to 10 g/1.

The invention is in particular suitable for multifunctional machine dishwash detergent compositions. However, also benefits can be achieved by applying the invention to a detergent composition in which a separate rinse aid is used in the final steps of the dishwashing process. In a preferred embodiment the detergent composition is a multifunctional machine dishwash composition.

The invention in all of its embodiments is in particular beneficial for detergent compositions which are in particulate form. The particulate detergent composition may be in powder form or tablet form, or a combination thereof. Builder

The compositions of the invention will contain one or more amino polycarboxylic compounds. These compounds act as builders, and bind ions like magnesium and calcium.

Because of the cleaning properties and good performance at decreased pH, the amino polycarboxylic compound is selected from methylglycine diacetic acid (MGDA) and iminodiacetic acid (IDS) . The most preferred type of amino polycarboxylic compound is MGDA.

Optionally the composition comprises a further builder which may be selected for example from the group comprising alkali metal carbonates, bicarbonates, borates and zeolites.

In compositions of the current invention the amount of amino polycarboxylic compound, preferably MGDA, is at least 25 wt%, and is preferably between 25 and 70 wt% of the total composition, more preferred between 25 and 60 wt%, and most preferred between 30 and 45 wt%. An amount of about 30, 35 or 40 wt% of MGDA was found to lead to good results on all aspects in the detergent composition of the current invention.

The form in which the MGDA and/or IDS and/or their salts can be applied in the compositions can be any, and for this invention is preferably the form of a powder or a granule.

The compositions of the present invention are substantially free from phosphate containing builders. Examples of phosphate containing builders are tripolyphosphates, hexametaphosphate, orthophosphate, and the alkali metal salts thereof. Inorganic bleach component

In the composition of the current invention the amount of percarbonate present is in the range of 3-12 wt%. It was found that despite these low amounts of percarbonate present, very good cleaning performance is obtained. Such good results are in particular found when the amount of percarbonate is at least 5%, and preferably between 5 and 11 wt%. Even further preferred the amount is between 7 and 11 wt%, most preferred it is between 8 and 11 wt%, and highly preferred it is about 9 or 10 wt%, based on total composition.

It is highly preferred that the percarbonate material used is coated. The coating of the material can be done by, for example, crystallisation or by spray granulation. Suitable coated percarbonate material is described in, for example, EP 891417, EP 136580 and EP 863842. The use of spray granulated coated percarbonate is most preferred.

In a preferred embodiment of the invention, the machine dishwash composition comprises 30-45 wt% of MGDA, and 8-11 wt% of a spray granulated coated percarbonate.

The compositions of the invention have a good stability both on production and storage. In particular, good cleaning performance is obtained while the degradation of the product is reduced compared to the percarbonate products on the market these days. The stability can suitably be measured by using a Thermal Activity Monitor (TAM) , a multichannel microcalorimeter as for example supplied Thermometric . The object of the TAM measurement is to quantify the thermal activity of a product. The higher the thermal activity, which originates from reaction of ingredients, the greater the risk for product degradation under storage conditions.

For measurement of the heat generation in tablets or powders a sample is maintained at a constant temperature. Prior to the measurement the TAM apparatus is equilibrated at the desired measurement temperature, which typically is 40 or 50°C. The tablet is broken in half, and placed in a 25 ml vial in the apparatus. For measuring the heat generation in a powder, 10 gram of the powder is placed in the vial. The heat flow is recorded during at least 48 hrs . The value after exactly 48 hour is taken, and divided by the weight of the sample. The resulting TAM value is expressed in μW/g (micro Watt per gram) . It has been found that stable machine dishwash compositions can be prepared using an amino polycarboxylic compound selected from methylglycine diacetic acid (MGDA) and iminodiacetic acid (IDS), as a detergency builder and percarbonate as a bleaching agent which have a TAM value of less than 80 μW/g. at 50⁰C, and which have excellent cleaning performance. Hereto, the amount of amino polycarboxylic compound selected from MGDA and IDS is at least 25 wt.%, and the amount of percarbonate used is significantly less than commonly applied, namely being in the range of 3-12 wt.%, based on total product. Preferably, compositions according to the invention are prepared that have a TAM value of less than 70 μW/g. at 50⁰C, and further preferred a TAM value of less than 60 μW/g. at 50°C.

Silicates In commonly used detergent formulations not according to the current invention, silicate is present in amounts up to 30 wt% or even higher, around 50 wt%. Purpose of the silicate in those known compositions is often to prevent fading of colours on glaze porcelain and decorated glasses via corrosion, as well as on enamel and metal corrosion.

It has now been found that by the incorporation of a small amount of silicate, the amount being in the range of 2 to 7 wt%, not only still a good reduction of aluminum corrosion was observed, but also a further improvement of the stability of the dishwash compositions is found. TAM values were found to be further reduced when 2 to 7 wt% silicates are present in a composition comprising at least 25 wt% MGDA, preferably between 25 and 70 wt%, and 3 to 12 wt% percarbonate .

When using amounts of less than 2 wt% stability and corrosion benefits are hardly detectable, whereas an amount higher than 7 wt% was found to lead to disadvantages in the composition.

Preferably, the amount of silicate used is selected in the range of 3 to 6 wt%. A further improvement comprises a dishwash composition containing at least 25 wt% MGDA, preferably between 25 and 70 wt%, 3 to 12 wt% percarbonate, and 3 to 6 wt% silicates .

The silicate levels indicated in the specification are calculated as Siθ2.

It is preferred that the silicate is chosen from the group of alkali metal silicates. The silicate may provide pH adjusting capability and protection against corrosion of metals and against attack on decor on dishware, including fine china and glassware benefits. The ratio of Siθ2 to the alkali metal oxide (M₂O , where M=alkali metal) is typically from 1 to 3.5, preferably from 1.6 to 3, more preferably from 2 to 2.8. Preferably, the alkali metal silicate is hydrous, having from 15% to 25% water, more preferably, from 17% to 20%.

The highly alkali metasilicates can in principle be employed, but in general, yield too high a pH to be suitable for application in the compositions of the current invention. Therefore, the less alkaline hydrous alkali metal silicates having a Siθ2:M₂O ratio of from 2.0 to 2.4 are, greatly preferred. Anhydrous forms of the alkali metal silicates with a Siθ2:M₂O ratio of 2.0 or more are less preferred because they tend to be significantly less soluble than the hydrous alkali metal silicates having the ratio of less than 2.

From the alkali metal silicates, sodium and potassium, and especially sodium, silicates are preferred. A particularly preferred alkali metal silicate is a granular hydrous sodium silicate having a Siθ2:Na2<0 ratio of from 2.0 to 2.4. Most preferred is a granular hydrous sodium silicate having a Siθ2:Na2<0 ratio of 2.0, in particular for application in machine dishwash detergent compositions applied in powder or tablet form. While typical forms, i.e. powder and granular, of hydrous silicate particles are suitable, preferred silicate particles having a mean particle size between 300 and 900 μm and less than 40% smaller than 150 μm and less than 5% larger than 1700 μm. Particularly preferred is a silicate particle with a mean particle size between 400 and 700 μm with less than 20% smaller than 150 μm and less than 1% larger then 1700 μm.

Nonionics Optionally, one or more nonionic surfactants may be present in the compositions of the invention. The compositions of the invention can contain a total amount of nonionic surfactants in the compositions of up to 10 wt%, more preferred up to 7 wt%, most preferred up to 5 wt% of a nonionic when surfactant is present. Preferably, the total amount of nonionic surfactants present in the compositions is at least 0.5 wt%, more preferred at least 0.8 wt%. Suitably, the total amount of nonionic surfactants in the compositions is in the range of 1 to 5 wt% of the total composition.

These nonionic surfactants may include any alkoxylated nonionic surface-active agent wherein the alkoxy moiety is selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof. The nonionic surfactants are preferably used to improve the detergency and to suppress excessive foaming due to protein soil. Examples of suitable nonionic surfactants are low- to non-foaming ethoxylated and/or propoxylated straight chain fatty alcohols.

The disadvantage of formulations containing amino polycarboxylate compounds like methylglycine diacetic acid as builder, and conventional nonionic surfactants (meaning nonionic surfactants that are liquid at temperatures below 35°C), is that due to its hygroscopicity, the polycarboxylate compounds will show caking. For example, when manufacturing a premix of powders and other ingredients of the machine dishwash composition, the powder flow through pipes and into packaging machines is hampered by stickiness of the powder. This is especially relevant when the machine dishwash composition is compressed into tablets. As multifunctional tablets contain rather high amounts of nonionics, compared to non- multifunctional detergent tablets, this problem at manufacturing is even more present. A further improvement of phosphate free machine dishwash compositions containing amino polycarboxylate compounds such as MGDA, and percarbonate was found when less than 2 wt% of nonionic surfactants with a melting point of less than 35°C is present in the composition.

Surprisingly we have found that by the use of one more nonionic surfactants with a melting point above 35°C in the dishwash compositions of the invention the rinse efficiency performance is improved compared to a tablet with nonionics that are liquid at temperatures below 35°C.

Machine dishwash compositions comprising one or more nonionic surfactants with a melting point above 35°C are preferred. Another preferred embodiment contains less than 2 wt% of nonionic surfactants with a melting point of less than 35°C and contains one or more nonionic surfactants with a melting point above 35°C.

In a further preferred embodiment at least one nonionic surfactant has a melting point higher than 40⁰C.

The amount of the nonionic surfactant with a melting point higher than 35°C in the composition is preferably at least 0.5 wt%. More preferably the amount is at least 0.8 wt%, most preferred at least 1.5 wt%, based on the weight of the total composition.

Suitably, the dishwash composition comprises at least 25 wt% MGDA, preferably between 25 and 70 wt%, 3 to 12 wt% percarbonate, less than 2 wt% of nonionic surfactants with a melting point of less than 35°C. A further improvement comprises a dishwash composition comprises at least 25 wt% MGDA, preferably between 25 and 70 wt%, 3 to 12 wt% percarbonate, less than 2 wt% of nonionic surfactants with a melting point of less than 35°C, and at least 0.5 wt%, preferably at least 0.8 wt% of a nonionic surfactant with a melting point higher than 35°C. By the additional presence of 2 to 7 wt% of silicates in any of these compositions the benefits in production, cleaning performance with reduced metal corrosion, and stability of the detergent product is even further improved.

A further improvement of this embodiment involves the use of a nonionic surfactant with a melting point higher than 35°C, that is a low foaming nonionic surfactant. A preferred nonionic surfactant with a melting point higher than 35°C is selected from hydroxyalkyl glycolether surfactants having a melting point above 35°C, preferably above 40⁰C. A preferred class of such materials has from 6 to 20, preferably from 8 to 18, most preferred from 10 to 18 carbon atoms in the alkyl chain thereof and from 15 to 50, preferably from 20 to 40 glycol ether units. An example of compounds from this group is the class of modified fatty alcohol polyglycolethers . Other preferred nonionic surfactants of this group are high melting point polyalkoxylated alcohols, optionally with the -OH group endcapped such as with an alkyl group and typically having an average of 10 to 20 alkyl groups and more than 30 alkylene oxide groups, e.g. ethylene oxide and/or proplylene oxide groups .

Preferably at least 50 wt% of the total amount of nonionic surfactants is a nonionic surfactant that has a melting point higher than 35°C, more preferred at least 60 wt%, and most preferred at least 65 wt%. Optionally up to 90% or even 100% by weight of the total nonionic surfactants are selected from nonionic surfactants that have a melting point higher than 35°C.

The high melting point nonionics can be added to the composition in different ways. They can be added, for example by CO- extrusion with the amino polycarboxylic compound, by co- granulation, or the like. We have found that the benefits described in this description are also obtained by simple addition of granules of the high melting nonionics to all or part of the ingredients in the preparation of the composition.

In addition to nonionic surfactants, the compositions may comprise anionic surfactants. If present, the total amount thereof should be at levels of less than 5 wt%, and preferably at levels of 2 wt% or below. Furthermore, if any anionic surfactant is present, it is preferred that an antifoam agent to suppress foaming is present.

In a particular embodiment, the invention provides a machine dishwash composition which is substantially free of phosphate, and comprising 25 to 70 wt% MGDA, 3 to 12 wt% percarbonate, 2 to 7 wt% silicate, less than 2 wt% of nonionic surfactants with a melting point of less than 35°C and at least 0.5 wt% of one or more nonionic surfactants with a melting point above 35°C.

Other ingredients of the compositions Bleach Material

In addition to the percarbonate bleach material other bleach components may be present in the composition. As inorganic bleaching agents both the peroxygen bleaching agents as well as chlorine- or bromine-releasing agents are suitable for inclusion in the machine dishwashing compositions. For example, 1-5 wt% of a chlorine bleaching agent may be used. Peroxygen based bleach materials are however preferred. The bleach material can completely or partially be encapsulated.

Inorganic peroxygen-generating compounds are also typically used as the bleaching material of the present invention. Examples of these materials are acids and corresponding salts of monopersulphate, perborate monohydrate, and perborate tetrahydrate .

Monoperoxy acids useful herein include alkyl peroxy acids and aryl peroxyacids such as peroxybenzoic acid and ring-substituted peroxybenzoic acids (e.g. peroxy-alpha- naphthoic acid) , aliphatic and substituted aliphatic monoperoxy acids (e.g. peroxylauric acid and peroxystearic acid), and phthaloyl amido peroxy caproic acid (PAP) . Typical diperoxy acids useful herein include alkyl diperoxy acids and aryldiperoxy acids, such as 1, 12-di-peroxy-dodecanedioic acid (DPDA), 1, 9-diperoxyazelaic acid, diperoxybrassylic acid, diperoxysebacic acid and diperoxy-isophthalic acid, and 2-decyldiperoxybutane-l, 4-dioic acid.

Peroxyacid bleach precursors are well known in the art. As non- limiting examples can be named N, N, N ' , N ' -tetra- acetylethylenediamine (TAED) , sodium nonanoyloxybenzene sulphonate (SNOBS), sodium benzoyloxybenzene sulphonate (SBOBS) and the cationic peroxyacid precursor (SPCC) as described in US 4,751,015.

If desirable a bleach catalyst, such as the manganese complex, e.g. Mn-Me TACN, as described in EP 458 397 A, or the sulphonimines of US 5,041,232 and US 5,047,163, may be incorporated. This may be presented in the form of an encapsulate separately from the percarbonate bleach granule. Cobalt catalysts may also be used.

For peroxygen bleaching agents a suitable range is from 0.5% to 3% avO (available Oxygen) . Preferably, the amount of bleach material in the wash liquor is at least 0.00125 wt% and at most 0.03 wt% avO by weight of the liquor.

Bismuth salt

The composition of the invention may comprise a water soluble salt of bismuth. Where bismuth is mentioned, a soluble salt of bismuth is meant, unless indicated otherwise.

For the purpose of preventing visible glass corrosion and decor fading, the level of water soluble bismuth salt in the machine dishwash detergent composition of the invention is preferably less than or equal to 3 wt%, based on the total composition. Although it has been observed that at very low levels of bismuth, an effect can already be obtained, the composition of the invention contains effectively at least 0.05 wt%. Accordingly, in a preferred embodiment, the composition of the invention comprises from 0.05 wt% to 3 wt%, based on the total composition, of bismuth. In a further preferred embodiment the composition contains 0.1 to 2 wt% of the water soluble salt of bismuth .

Water soluble bismuth salts suitable for use in the detergent compositions of the invention are in particular selected from the group of bismuth acetate, acetate dihydrate, bromide, butyrate, citrate, citrate dihydrate, chloride, iodide, iodide dihydrate, caproate, formate, formate dihydrate, fumarate, gluconate, glycinate, lactate, malate, maleate, nitrate, nitrate trihydrate, nitrate hexahydrate, phenolsulphonate, sulphate monohydrate, sulphate heptahydrate, sulphate hexahydrate, salicylate, succinate, tartrate, valerate, saccharinate, and carboxymethyl oxysuccinate . It is preferred to use a water soluble bismuth salt composition chosen from the group of acetate, formate, and sulphate. Mixtures of any of the salts mentioned can also be used.

Antiscalant Polymer

In a preferred embodiment of the current invention, the machine dishwash detergent composition comprises at least one dispersing polymer. Dispersing polymers as referred to in this invention are chosen from the group of anti-spotting agents and/or anti-scaling agents.

Examples of suitable anti-spotting polymeric agents are hydrophobically modified polyacrylates, whereas also synthetic clays, and preferably those synthetic clays which have a high surface area are very useful to prevent spots, in particular those formed where soil and dispersed remnants are present at places where the water collects on the glass and spots formed when the water subsequently evaporates. Antispotting systems such as hydrophobically modified polyacrylates are advantageous in the so called multifunctional systems.

Examples of suitable anti-scaling agents include organic phosphonates, amino carboxylates, polyfunctionally-substituted compounds, and mixtures thereof. Particularly preferred anti-scaling agents are organic phosphonates such as α-hydroxy-2-phenyl ethyl diphosphonate, ethylene diphosphonate, hydroxy-1, 1-hexylidene, vinylidene 1,1- diphosphonate, 1, 2-dihydroxyethane-l, 1-diphosphonate and hydroxy-ethylene-1, 1-diphosphonate . Most preferred is hydroxy- ethylene-1 , 1-diphosphonate (EDHP) and 2-phosphono-butane-l, 2, 4- tricarboxylic acid.

Especially preferred are water soluble dispersing polymers prepared from an allyloxybenzenesulfonic acid monomer, a methaiIyI sulfonic acid monomer, a copolymerizable nonionic monomer and a copolymerizable olefinically unsaturated carboxylic acid monomer as described in US 5,547,612 or known as acrylic sulphonated polymers as described in EP 851 022. Polymers of this type include polyacrylate with methyl methacrylate, sodium methallyl sulphonate and sulphophenol methallyl ether. Also suitable are a terpolymer containing polyacrylate with 2-acrylamido-2 methylpropane sulphonic acid, as well as phosphonated polyacrylates, and ethoxylated polycarboxylates .

As an alternative, polymers and co-polymers of acrylic acid having a molecular weight between 500 and 20,000 can also be used, such as homo-polymeric polycarboxylic acid compounds with acrylic acid as the monomeric unit. The average weight of such homo-polymers in the acid form preferably ranges from 1,000 to 100,000 particularly from 3,000 to 10,000. Also suitable are polycarboxylates co-polymers derived from monomers of acrylic acid and maleic acid. The average molecular weight of these polymers in the acid form preferably ranges from 4,000 to 70,000.

Also mixtures of anti-scaling agents may be used, particularly useful is a mixture of organic phosphonates and polymers of acrylic acid with methyl methacrylate, sodium methaiIyI sulfonate .

It is preferable if the level of anti-scaling agent is from 0.2 to 15 wt% of the total composition, preferably from 0.5 to 10 wt%, and further preferred 1 to 8 wt%.

Enzymes

Enzymes may be present in the compositions of the invention. Examples of enzymes suitable for use in the cleaning compositions of this invention include lipases, peptidases, amylases (amylolytic enzymes) and others which degrade, alter or facilitate the degradation or alteration of biochemical soils and stains encountered in cleansing situations so as to remove more easily the soil or stain from the object being washed to make the soil or stain more removable in a subsequent cleansing step. Both degradation and alteration can improve soil removal. Preferably, the composition of the invention also contains a proteolytic enzyme. Enzymes may be present in a weight percentage amount of from 0.2 to 7% by weight.

Anti-tarnishing Agents

Anti-tarnishing agents such as benzotriazole and those described in EP 723 577 may also be included.

Optional Ingredients Optional ingredients are, for example, buffering agents, reducing agents, e.g., borates, alkali metal hydroxide and the well-known enzyme stabilisers such as the polyalcohols, e.g. glycerol and borax, crystal-growth inhibitors, threshold agents, perfumes and dyestuffs and the like. In tablets binding agents can be used e.g. modified starches.

Reducing agents may be used, e.g., to prevent the appearance of an enzyme-deactivating concentration of oxidant bleach compound. Suitable agents include reducing sulphur-oxy acids and salts thereof. Most preferred for reasons of availability, low cost, and high performance are the alkali metal and ammonium salts of sulphuroxy acids including ammonium sulphite ( (NH₄) 2SO3), sodium sulphite (Na2SO3) , sodium bisulphite (NaHSOs) , sodium metabisulphite (Na2S2<03) , potassium metabisulphite (K2S2O5) , lithium hydrosulphite (Li₂S2θ₄) , etc., sodium sulphite being particularly preferred. Another useful reducing agent, though not particularly preferred for reasons of cost, is ascorbic acid. The amount of reducing agents to be used may vary from case to case depending on the type of bleach and the form it is in, but normally a range of about 0.01 wt% to about 1.0 wt%, preferably from about 0.02 wt% to about 0.5 wt%, will be sufficient.

In a preferred embodiment, the composition according to the invention comprises a rinse aid composition/ingredient. Rinse aid ingredients are ingredients that effect that final appearance of the table ware that is washed.

Rinse sufficiency methods

In a further aspect of the current invention a method for cleaning dishware in a mechanical dishwashing machine is provided, comprising treatment of the dishware with a wash liquor comprising a dishwashing composition according to the invention as specified before. In a preferred embodiment minimal rejuvenation of ion exchange material within the machine is needed. In this embodiment there is no need for the consumer to add salt to the designated salt compartment in the machine. The compositions especially suitable for this use are multifunctional compositions.

In a still further aspect, the invention relates to the use of a dishwashing composition according to the invention for use in an automatic dishwashing machine, such that no salt is required for the rejuvenation of ion exchange material within the machine .

Forms of detergent compositions Suitable forms for the machine dishwash detergent composition are powders and tablets and mixtures thereof. Preferably the compositions are unit dose compositions such as tablets. Unit dose compositions such as tablets may be wrapped in a water soluble wrap for easy handling. In the context of this specification, a tablet is understood to be a compressed particulate composition that can be considered to be a solid shaped body.

In a preferred embodiment the detergent tablets of the present invention can be monophase tablets, as well as multiphase tablets. These phases may have a different colour and each phase may comprise different ingredients, which may be active in the sequential steps of washing. The phases of the multiphase detergent tablet are preferably separate layers within the tablet. However, a discrete region of a tablet could also have any other form, for example one or more cores, or inserts, in the form of a sphere.

In one embodiment the detergent tablet of the present invention is a three-layer tablet, in which the upper and bottom layer substantially have the same composition, while the middle layer has a different composition.

The tablets may be of any shape. However, for ease of packaging they are preferably blocks of substantially uniform cross- section, such as cylinders or cuboids. In general the upper and lower surfaces of the tablet are substantially flat. The overall density of a tablet preferably lies in a range from 1000 up to 1700 g/L.

Preferably the phases of the preferred tablet together have a weight of 5 to 70 gram, more preferred 10 to 40 gram. The weight of the tablets depends on the conditions of intended use, and whether it represents a dose for an average load in a dishwashing machine or a fractional part of such a dose. As indicated earlier in this specification, machine dishwash detergent compositions according to the invention may suitably be dosed in the wash liquor at levels of from 2 g/1 to 10 g/1.

EXAMPLES

The following non-limiting examples illustrate the present invention. Ingredients are indicated as weight percentage of the total composition, unless indicated otherwise.

Example 1

Machine dishwash detergent tablets were prepared using the formulations as indicated in Table I .

Table I

polyethylene glycol 1.67 1.67 1.67 sulphonated polymer 0.37 0.37 0.37

*alkylhydroxyether, melting point between 45-49°Celsius

Powder preparation

50kg of each of the powder compositions indicated in the Table was prepared in a 130 1. high shear ploughshare mixer. For the white powder preparation, the bulk materials methylglycine diacetic acid, sodium sulphate, and sodium bicarbonate are dosed to the mixer first, followed by the spraying of the liquids onto the powder in approximately 30 seconds. After spraying, the minor components are dosed to the mixer and the powder is mixed for 1.5 minute before discharging into drums.

Triple layer tablet preparation

Triple layer tablets in this example are produced on a rotary tablet press with 3 dosing stations. The white powder was used for the top and bottom layer compositions and the green powder was used for the middle layer compositions. The turret of the machine is equipped 37 punch stations with a length of 36 mm and a width of 26 mm. In dosing stations 1 and 3 the particulate compositions of the top and bottom layer are dosed, and in dosing station 2 the particulate compositions of the middle layer are dosed. The turret speed is set on 5 rpm. Tablets are compressed by first dosing (station 1) 8 g of the particulate compositions of the top and bottom layer, followed by (station 2) 3 g of the particulate composition of the middle layer, and again (station 3) 7 g particulate compositions of the top and bottom layer. This results in rectangular tablets with a total weight of 18 g, a width of 26 mm, and a length of 36 mm. Of all tablets, the stability was measured using the Thermal Activity Monitor (TAM) as described in the description, whereby the TAM apparatus is equilibrated at 50⁰C.

The TAM values found are indicated in Table II.

Table II

This clearly shows superior stability for the tablets of the invention. All tablets showed equal cleaning performance.

Example 2

Another series of machine dishwash detergent tablets was prepared, now using the formulations as indicated in Table III Table III

"'alkylhydroxyether, melting point between 45-49 Celsius

Powder preparation was as described in example 1. From the powder, tablets were made as described in example 1. Of all tablets, the stability was measured using the Thermal Activity Monitor (TAM) as described in this patent specification, whereby the TAM apparatus is equilibrated at 50⁰C. TAM values found were

Table IV

This clearly shows superior stability for the tablets of the invention .

Cleaning test

The cleaning efficiency behaviour of tablets C, and comparative examples II and III were tested in a dishwashing machine. The dishwash machine used was a Miele G651SC plus, that was cleaned before start of the test. The programme was 50⁰C normal. The diswash product is dosed via the dispenser, and water hardness was 27/9°FH.

The machine was loaded with soiled plates, glasses and cutlery. The dishwash programme is started. After the wash programme, the (clean) dishes are scored on residual soil and against completely clean dishes.

Dirt (localised deposits) was scored in a viewing cabinet with a scoring scale of 1-10, the higher, the better. In this assessment example C scored 6.7, comparative examples

II and III scored 6.8 and 6.6 respectively. With the accuracy of data of +/- 0.3, this means that despite the reduced amount of percarbonate, the products of the current invention have an equal cleaning performance contrary to what would be expected. Accordingly, and improved product is obtained with an improved stability without a reduction of performance.

Claims

1. A machine dishwash detergent composition which is substantially free of phosphate, and comprises an amino polycarboxylic compound selected from methylglycine diacetic acid (MGDA) and iminodiacetic acid (IDS), in an amount of at least 25 wt%, preferably between 25 and 70 wt%, and a bleaching agent comprising percarbonate, the amount of percarbonate being in the range of 3 to 12 wt% based on total weight of the composition.

2. A composition according to claim 1, in which the amino polycarboxylic compound comprises methylglycine diacetic acid and/or its corresponding salts.

3. A composition according to claim 1 or 2, in which the amount of amino polycarboxylic compound is between 25 and 60 wt%, preferably between 30 and 45 wt%.

4. A composition according to any one of claims 1 to 3, wherein percarbonate is present in an amount between 5 and 11 wt%, preferably between 8 and 11 wt%.

5. A composition according to any one of claims 1 to 4, were in the percarbonate is a coated percarbonate.

6. A composition according to any one of the preceding claims, wherein silicate is present in an amount between 2 and 7 wt%, preferably between 3 and 6 wt%.

7. A composition according to any one of the preceding claims, wherein the composition contains less than 2 wt% of a nonionic surfactant having a melting point of less than 35°C.

8. A composition according to any one of the preceding claims, wherein the composition contains at least 0.5 wt%, preferably at least 0.8 wt% of a nonionic surfactant with a melting point higher than 35°C.

9. A composition according to any one of the preceding claims, additionally comprising a water soluble salt of bismuth in an amount of between 0.05 and 3 wt%.

10. A composition according to any one of the preceding claims, wherein the composition is in the form of a powder or a tablet.

11. A composition according to any one of the preceding claims, wherein the composition is a multifunctional machine dishwash composition.

12. A method for cleaning dishware in a mechanical dishwashing machine, comprising treating the dishware with a wash liquor comprising a dishwashing composition according to any of the preceding claims.

13. The use of a dishwashing composition according to any of claims 1 to 12 in an automatic dishwashing machine, such that no salt is required for rejuvenation of ion exchange material within the machine.