EP1518922A1

EP1518922A1 - Machine dishwashing formulations

Info

Publication number: EP1518922A1
Application number: EP03078060A
Authority: EP
Inventors: Ian C. c/o Unilever R&D Vlaardingen Callaghan; Naresh D. c/o Unilever R&D Vlaardingen Ghatlia
Original assignee: Unilever NV
Current assignee: Unilever NV
Priority date: 2003-09-26
Filing date: 2003-09-26
Publication date: 2005-03-30

Abstract

The invention provides an aqueous machine dishwashing formulation comprising at least 10wt% water, a tripolyphosphate builder material and from 0.01 to 3.5wt% of an organic amine compound.

The formulations show a significant improvement in tripolyphosphate stability. This provides a beneficial reduction in filming, spotting or other unsightly deposits caused by tripolyphosphate breakdown products. Preferably the formulations are in the form of a gel and are packaged in a water-soluble sachet.

Description

Field of the Invention

This invention relates to aqueous machine dishwashing formulations comprising a tripolyphosphate builder material.

Background and Prior Art

Machine dishwashing agents typically include a variety of specialised components for specific purposes during the multi-step wash cycle.
Builders are especially important to improve washing performance. For machine dishwashing applications, many factors must be considered in selecting a suitable builder, including alkalinity, pH, buffering ability, water softening ability, stability and cost effectiveness.
Phosphates are extremely effective and widely used in the above context, with tripolyphosphate materials being particularly preferred.
A problem with the use of tripolyphosphate builders is that they can break down in aqueous environments. The breakdown process is exacerbated by prolonged storage at high temperatures, and by low formulation pH. The breakdown products formed are ortho and pyrophosphate derivatives. These have a tendency to form highly insoluble precipitates, especially in hard water areas, which can lead to unsightly deposits in the dishwashing machine and on the treated dishware. If the level of tripolyphosphate in the formulation is reduced to counteract the problem of these deposits, then the overall cleaning performance of the formulation may be compromised.
The present inventors have found that the presence of organic amine compounds gives a significant improvement in tripolyphosphate stability in an aqueous environment such as an aqueous liquid or gel machine dishwashing formulation. This provides a beneficial reduction in filming; spotting or other unsightly deposits caused by tripolyphosphate breakdown products.
Organic amine compounds have been suggested for use in machine dishwashing formulations.
US2002/0142931 discloses a machine dishwashing gel in which the matrix of the gel comprises an organic solvent system such as an organoamine solvent, for improved removal of cooked-, baked- or burnt-on food soil from cookware and tableware. The composition is said to be "essentially anhydrous", meaning that it contains less than about 5%, preferably about 1% free moisture.
WO02/08370 and WO02/08731 provide a method of removal of cooked-, baked-, or burnt-on food soil from cookware and tableware by washing in an automatic dishwashing machine in the presence of an organic solvent system having a wash liquor concentration of from 100 to 5000 ppm. Preferred solvent systems comprise alkanolamines such as monoethanolamine and 2-(methylamino)ethanol. The organic solvent system may be used separately as a pre-treatment or incorporated into an "all-in-one" dishwashing product, and is said to improve the removal of burnt-on soils having a high carbon content.
US 6,034,044 describes an automatic dishwashing detergent comprising builder and a mixed nonionic surfactant system comprising low cloud point and high cloud point surfactants. Organic amines such as ethylenediaminetetraacetic acid (EDTA) or monoethanolamine are mentioned as optional additives for the stabilization of enzymes. The compositions of US 6,034,044 are preferably granular with the free moisture content kept at a minimum, such as 7% or less, preferably 4% or less.
None of the above-cited prior art is addressed to the problem of tripolyphosphate stability in an aqueous environment such as an aqueous liquid or gel machine dishwashing formulation.

Summary of the Invention

In a first aspect, the present invention provides an aqueous machine dishwashing formulation comprising at least 10wt% water, a tripolyphosphate builder material and from 0.01 to 3.5wt% of an organic amine compound.

Detailed Description of the Invention

Organic amine compound

The aqueous machine dishwashing formulation of the invention comprises from 0.01 to 3.5wt% of an organic amine compound.
Suitable organic amine compounds may be selected from alkanolamines (e.g. primary alkanolamines: monoethanolamine, monoisopropanolamine, diethylethanolamine, ethyl diethanolamine; secondary alkanolamines: diethanolamine, diisopropanolamine, 2-(methylamino)ethanol, morpholine; ternary alkanolamines: triethanolamine, triisopropylamine); alkylamines (e.g. primary alkylamines: monomethylamine, monoethylamine, monopropylamine, monobutylamine, monopentylamine, cyclohexylamine; secondary alkylamines: dimethylamine) alkyleneamines (e.g. primary alkylene amines: ethylenediamine, propylenediamine, triethylenetetramine), and mixtures thereof. Preferred examples of such materials include monoethanolamine, diethanolamine, ethylenediamine, triethylenetetramine, morpholine and mixtures thereof. More preferred are monoethanolamine, ethylenediamine, triethylenetetramine and mixtures thereof. Most preferred is monoethanolamine.
The amount of organic amine compound in the aqueous machine dishwashing formulation of the invention preferably ranges from 0.1 to 2.5 wt%, most preferably from 0.2 to 2 wt%, by total weight of the organic amine compound based on the total weight of the aqueous machine dishwashing formulation.

Tripolyphosphate builder material

The aqueous machine dishwashing formulation of the invention comprises a tripolyphosphate builder material.
The tripolyphosphate builder materials which may be used in this invention are well known, for example, for binding metals such as Ca and Mg ions, both of which are often abundant in hard water found in dishwashing machines. An illustrative list of the tripolyphosphate builders which may be used in this invention include alkali metal tripolyphosphates such as sodium and potassium tripolyphosphate, with potassium tripolyphosphate (KTP) being especially preferred.
Such tripolyphosphate builder materials can typically make up from 5 to 75wt% by weight based on the total weight of the aqueous machine dishwashing formulation. Preferably, however, to ensure optimum stability of the formulation without compromising cleaning performance, the amount of tripolyphosphate builder material ranges from 10 to 70wt%, and most preferably from 20 to 50wt%, by total weight of the tripolyphosphate builder material based on the total weight of the aqueous machine dishwashing formulation.

Product Form

The aqueous machine dishwashing formulation of the invention may be in the form of a liquid, but is preferably in the form of a gel. Gel, as used herein, is defined to mean any liquid having a viscosity of greater than about 100 cps and less than about 45,000 cps, measured at a shear rate of 1/s at ambient temperature.
Such a gel will preferably have a viscosity ranging from 200 to 30,000 cps, and most preferably, from 300 to 25,000 cps, at ambient temperature.

Optional Components

The aqueous machine dishwashing formulation comprises, as essential components, at least 10wt% water, a tripolyphosphate builder material and from 0.01 to 3.5wt% of an organic amine compound.
The formulation may also comprise optional ingredients for enhancing performance and/or aesthetics.

Examples of preferred optional ingredients are as follows:

Anti-spotting agents

Preferred anti-spotting agents for use in this invention comprise a hydrophobically modified polycarboxylic acid.
Such a hydrophobically modified polycarboxylic acid often has a weight average molecular weight of greater than 175 and less than 1.5 million, and preferably, greater than 200 and less than 1 million; and most preferably, greater than 225 and less than 750 thousand.
The preferred hydrophobically modified polycarboxylic acid which may be used in this invention comprises at least one structural unit of the formula:
and
wherein each R¹ and R² are independently a hydrogen, hydroxy, alkoxy, carboxylic acid group, carboxylic acid salt, ester group, amide group, aryl, C_1-20 alkyl, C_2-20 alkenyl, C_2-20 alkynyl or a polyoxyalkylene condensate of an aliphatic group, n is an integer from 0 to 8, z is an integer from 1 to 8, t is an integer from 0 to 2,000 and a is an integer from about 0 to 2,000, with the proviso that a and t are not simultaneously 0 and at least one R¹ or one R² is a carboxylic acid group, or a salt thereof.
In a preferred embodiment, the hydrophobically modified polycarboxylic acid used in this invention comprises at least one structural unit represented by formula I (t is greater than or equal to 1) with at least one R¹ as a carboxylic acid group (or salt thereof), and at least one structural unit represented by formula II (a is greater than or equal to 1) with at least one R² group as a C_4-20 alkyl group or a C_8-30 ethoxylated condensate of an aliphatic group.
In a most preferred embodiment the modified polycarboxylic acid used in this invention comprises structural units represented by formula I and structural units represented by formula II wherein a is from about 80% to about 120% of t, and at least two R¹ groups are carboxylic acid groups (or salts thereof) and at least one R² group is a methyl group and at least one R² group is a C₅ alkyl, and n is 0 and z is 1.
The hydrophobically modified polycarboxylic acids which may be used in this invention are typically prepared by reacting the desired precursors (sp² bonded monomers) under free radical polymerization conditions. Such polycarboxylic acids are also commercially available from suppliers like Rohm & Haas and DuPont. A more detailed description of the types of hydrophobically modified polycarboxylic acids which may be used in this invention, including the process for making the same, may be found in U.S. Patent No. 5,232,622.
The preferred and most preferred hydrophobically modified polycarboxylic acids are made available by Rohm & Haas under the names Acusol 820 and 460, respectively.
Typically, from 0.1 to 10.0wt%, and preferably, from 0.2 to 7.0wt%, and most preferably, from 0.3 to 5.0wt%, by weight based on the total weight of the aqueous machine dishwashing formulation is a hydrophobically modified polycarboxylic acid.

Anti-scaling agents

Suitable anti-scaling agents for use in the invention include water soluble polymers which reduce phosphate scale formation. Such a polymer often comprises at least one structural unit derived from a monomer having the formula:
wherein R³ is a group comprising at least one sp² bond, z is O, N, P, S, or an amido or ester link, A is a mono- or a polycyclic aromatic group or an aliphatic group and each p is independently 0 or 1 and B⁺ is a monovalent cation.
Preferably, R³ is a C₂ to C₆ alkene (most preferably ethene or propene). When R³ is ethenyl, Z is preferably amido, A is preferably a divalent butyl group, each t is 1, and B⁺ is Na⁺. Such a monomer is polymerized and sold as Acumer 3100 by Rohm & Haas.
Another preferred embodiment exists when the water soluble polymer is derived from at least one monomer with R³ as 2-methyl-2-propenyl, Z as oxygen, A as phenylene, each t as 1 and B⁺ as Na⁺, and at least one monomer with R³ as 2-methyl-2-propenyl, each t as 0 and B⁺ as Na⁺. Such monomers are polymerized and sold under the name Alcosperse 240 by Alco Chemical.
The polymers used may be homopolymers or copolymers, including terpolymers. Furthermore, the polymers may be terminated with conventional termination groups resulting from precursor monomers and/or initiators that are used.
Typically, from 0.5 to 10.0wt%, and preferably, from 1.0 to 7.0wt%, and most preferably, from 1.5 to 4.5wt% water soluble polymer is used, by weight based on the total weight of the aqueous machine dishwashing formulation. These water soluble polymers typically have a weight average molecular weight from about 1,000 to about 50,000.
Further suitable anti-scaling agents are the compounds that may be used to reduce carbonate scale formation. These include polyacrylates (and copolymers thereof) having a weight average molecular weight from about 1,000 to about 400,000. Such compounds are supplied by Rohm and Haas, BASF, and Alco Corp. Preferred copolymers include those derived from acrylic acid and maleic acid monomers like Sokalan CP5 and CP7 supplied by BASF, and Acusol 479N, supplied by Rohm & Haas. Copolymers of acrylic acid and methacrylic acid (Colloid 226/35), as supplied by Rhone-Poulenc, may also be used.
Other materials that may be used to reduce carbonate scale formation include phosphonate functionalized acrylic acid (Casi 773 as supplied by Buckman laboratories); copolymers of maleic acid and vinyl acetate, and terpolymers of maleic acid, acrylic acid and vinyl acetate (made commercially by Huls); polymaleates (like Belclene 200, as supplied by FMC); polymethacrylates, (like Tomal 850, as supplied by Rohm & Haas); polyaspartates; ethylene diamine disuccinate, organopolyphosphonic acids (and salts thereof) such as sodium salts of amino tri(methylenephosphonic acid), diethylene triamine penta (methylene phosphonic acid); hexamethylene diamine tetramethylene phosphonic acid; ethane 1-hydroxy-1,1-diphosphonic acid (HEDP); organomonophosphonic acids (and salts thereof) such as the sodium salt of 2-phosphono-1,2,4-butane tricarboxylic acid, all of which are sold under the Dequest line as supplied by Solutia.
Mixtures of any of the above-described materials can be used. It has been found that combinations of anti-scaling agents can be more effective at reducing calcium carbonate scale than individual anti-scaling agents themselves.
The materials that may be used to reduce carbonate scale formation typically make up from 0.01 to 10.0wt%, and preferably, from 0.1 to 6.0wt%, and most preferably, from 0.2 to 5.0wt%, by weight based on the total weight of the aqueous machine dishwashing formulation.

Surfactant

Preferred surfactants for use in the invention are nonionic surfactants. These nonionic surfactants can be broadly defined as surface active compounds with at least one uncharged hydrophilic substituent. A major class of nonionic surfactants are those compounds produced by the condensation of alkylene oxide groups with an organic hydrophobic material which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.
Particularly preferred nonionic surfactants have a cloud point in water of less than 60°C, preferably less than 50°C, and most preferably, less than 45°C. This typically enhances the wetting properties of glassware being cleaned.
Illustrative examples of various suitable nonionic surfactant types are polyoxyalkylene condensates of aliphatic carboxylic acids, whether linear- or branched-chain and unsaturated or saturated, especially ethoxylated and/or propoxylated aliphatic acids containing from about 8 to about 18 carbon atoms in the aliphatic chain and incorporating from about 2 to about 50 ethylene oxide and/or propylene oxide units. Suitable carboxylic acids include "coconut" fatty acids (derived from coconut oil) which contain an average of about 12 carbon atoms, "tallow" fatty acids (derived from tallow-class fats) which contain an average of about 18 carbon atoms, palmitic acid, myristic acid, stearic acid and lauric acid.
Other suitable nonionic surfactants include polyoxyalkylene condensates of aliphatic alcohols, whether linear- or branched-chain and unsaturated or saturated, especially ethoxylated and/or propoxylated aliphatic alcohols containing from about 6 to about 24 carbon atoms and incorporating from about 2 to about 50 ethylene oxide and/or propylene oxide units. Suitable alcohols include "coconut" fatty alcohol, "tallow" fatty alcohol, lauryl alcohol, myristyl alcohol and oleyl alcohol. Preferred examples of such materials are provided by BASF Corporation as a series under the tradename Plurafac. Particularly preferred surfactants are Plurafac LF 301, Plurafac LF 403 and Plurafac SLF-18. Also included within this class of nonionic surfactants are epoxy capped poly(oxyalkylated) alcohols as described in WO 94/22800. A preferred example of this class of material is provided under the tradename Poly-Tergent SLF 18B 45 by BASF Corporation.
Polyoxyethylene or polyoxypropylene condensates of alkyl phenols, whether linear- or branched-chain and unsaturated or saturated, containing from about 6 to 12 carbon atoms and incorporating from about 2 to about 25 moles of ethylene oxide and/or propylene oxide are other types of nonionic surfactants which may be used.
Other desired nonionic surfactants which may be used include polyoxyethylene-polyoxypropylene block copolymers having formulae represented as HO(CH₂ CH₂O)_a(CH(CH₃) CH₂O)_b(CH₂ CH₂O)_cH or HO(CH(CH₃) CH₂O)_d(CH₂ CH₂O)_e(CH(CH₃) CH₂O)_fH wherein a, b, c, d, e and f are integers from 1 to 350 reflecting the respective polyethylene oxide and polypropylene oxide blocks of said polymer. The polyoxyethylene components of the block polymer constitutes at least about 10% of the block polymer. The material preferably has a molecular weight of between about 1,000 and 15,000, more preferably from about 1,500 to about 6,000.
These materials are well known in the art. They are available as a series of products under the tradename "Pluronic" and "Pluronic R", from the BASF Corporation.
The amount of nonionic surfactant present within the aqueous machine dishwashing formulation of the invention is typically at least 0.5 wt. %, preferably from 1 to 15 wt. %, and most preferably, from 1.5 to 8 wt. %, by total weight nonionic surfactant based on the total weight of the aqueous machine dishwashing formulation.
Conventional dishwashing surfactants may also (optionally) be employed in this invention and these include anionic surfactants like alkyl sulfates and sulfonates as well as fatty acid ester sulfonates. Particularly, salts of (i.e., sodium, potassium, ammonium, and substituted ammonium salts such as mono-, di- and triethanolamine salts) anionic sulfates, sulfonates, carboxylates, and sarcosinates may be used. Other optional anionic surfactants which may be used include isethionates, like acyl-isethionates, N-acyltaurates, fatty acid amides of methyl tauride, alkyl succinates and sulfosuccinates; mono esters of sulfosuccinate; and diesters of sulfosuccinate. These types of surfactants often make up from 0% to 10wt% by total weight of these types of surfactants based on the total weight of the aqueous machine dishwashing formulation.

Bleach

Preferred bleaches which may be used in this invention are in discrete particulate form. Such particles will generally have an approximate diameter from 100 to 5,000 microns, and preferably, from 200 to 4,500 microns, and most preferably, from 300 to 3,500 microns.
Most preferably the discrete particulate bleach is an encapsulated bleach. Such a bleach (i.e., the core of the encapsulated bleach) includes organic and inorganic peracids as well as salts thereof. Illustrative examples include epsilon phthalimido perhexanoic acid (PAP) and Oxone®, respectively. The bleaches may be employed with bleach activators. Suitably, the bleach and the bleach activator collectively make up from 0.02 wt.% to 20.0 wt.% by weight based on the total weight of the aqueous machine dishwashing formulation.
The clad (i.e., outer shell) of the encapsulated bleach is typically a wax such as a paraffin wax. Such paraffin waxes desirably have low melting points, i.e., between 40°C and 50°C and a solids content of from 35% to 100% at 40°C and a solids content of from 0% to 15% at 50°C.
This melting point range for the clad material is desirable for several reasons. The minimum of 40°C generally exceeds any typical storage temperatures that are encountered by machine dishwashing formulations. Thus, the wax coat will protect the core throughout storage of the formulation. The 50°C melting point cap for the wax clad was selected as providing a wax which will quickly melt or soften early in any automatic dishwashing wash cycle. Melting or softening sufficient to release the core will occur because operating temperatures in automatic dishwashers are usually between 40°C and 70°C. Thus, the paraffin waxes of the invention will release the core material when the capsule is exposed to the warmed wash bath, but not before.
Paraffin waxes are selected over natural waxes for the subject invention because in liquid alkaline environments, natural waxes hydrolyse and are unstable. Moreover, melted paraffin waxes of the encapsulated bleaches used in the invention will remain substantially molten at 40°-50°C. Such molten wax is easily emulsified by surfactant elements in machine dishwashing formulations. Consequently, such waxes will leave less undesirable waxy residue on items to be cleaned than waxes with higher melting points.
Thus, the wax coat preferably does not include any paraffins having a melting point substantially above 50°C, lest the higher melting point components remain solid throughout the wash cycle and form unsightly residues on surfaces to be cleaned, nor any paraffins with solid contents discussed below.
The distribution of solids of the paraffin waxes of the invention ensures storage integrity of the encapsulated bleach particles at temperatures up to 40°C in either a liquid or moist environment while yielding good melting performance to release its active core during use at temperatures of about 50°C.
The amount of solids in a wax at any given temperature as well as the melting point range may be determined by measuring the latent heat of fusion of each wax by using Differential Scanning Calorimetry (DSC) by a process described in Miller, W.J. et al. Journal of American Oil Chemists' Society, July, 1969, V. 46, No. 7, pages 341-343. This procedure was modified as discussed below. DSC equipment used in the procedure is preferably the Perkin Elmer Thermoanalysis System 7 or the Dupont Instruments DSC 2910.
Specifically, the DSC is utilized to measure the total latent heat of fusion of multi-component systems which do not have a distinct melting point, but rather, melt over a temperature range. At an intermediate temperature within this range one is capable of determining the fraction of the latent heat required to reach that temperature.
When acquired for a multi-component mixture of similar components such as commercial waxes, this fraction correlates directly to the liquid fraction of the mixture at that temperature. The solids fraction for the waxes of interest are then measured at 40°C and 50°C by running a DSC trace from -10°C to 70°C and measuring the fraction of the total latent heat of fusion required to reach these temperatures. A very low temperature ramping rate of 1°C/min should be used in the test to ensure that no shifting of the graph occurs due to temperature gradients within the sample.
The more solids present in a wax at room temperature, the more suitable the wax is for use in making the clad; this is because such solids strengthen the wax coating, rendering the particle less vulnerable to ambient moisture or a liquid aqueous environment, whereas "oil" or liquid wax softens the wax, opening up pores in the coating and thereby provides poorer protection for the core of the particle. Significant solid paraffin remaining at 50°C may remain on the cleaned hard surfaces (e.g., dishware in an automatic dishwashing machine) and is undesirable.
Therefore, the wax solids content as measured by Differential Scanning Calorimetry for suitable paraffin waxes may range from 100% to 35%, preferably from 100% to 70%, at 40°C and from 0% to 15% and preferably 0% to 5% at 50°C.
Commercially available paraffin waxes which are suitable for encapsulating the solid core materials include Merck 7150 (54% solids content at 40°C and 2% solids content at 50°C) ex. E. Merck of Darmstadt, Germany; IGI 1397 (74% solids content at 40°C and 0% solids content at 50°C) and IGI 1538 (79% solids content at 40°C and 0.1% solids content at 50°C ex. The International Group, Inc. of Wayne, PA; and Ross fully refined paraffin wax 115/120 (36% solids content at 40°C and 0% solids content at 50°C) ex. Frank D. Ross Co., Inc. of Jersey City, NJ. Most preferred is IGI 1397.
Mixtures of paraffin waxes with other organic materials such as polyvinyl ethers as described in U.S. Patent Nos. 5,460,743 and 5,589,267 are also useful to make the clads.
Other bleaches which may be used include hydrogen peroxide and its precursors (e.g., sodium perborate and sodium percarbonate), alkyl, aryl and acyl peroxides such as benzoyl peroxide and solid chlorine bleach sources such as dichloroisocyanurate.
When preparing the discrete particulate encapsulated bleaches, the encapsulated particle is made via well known art recognized techniques which include spraying molten wax onto bleach particles in a fluidized bed. A preferred process is described in U.S. Patent No. 5,230,822. An encapsulated bleach (in the form of a discrete particle) is preferred in this invention since the clad prevents interactions between the bleach and other components of the formulation and/or between the bleach and the materials used to package the formulation.
If desired, conventional bleach activators (including catalysts) may be used with the bleaches described herein. These activators include (6-nonamidocaproxyl) oxybenzene sulfonate (as described in EPO 170,386) N,N,N',N'-tetraacetylethylenediamine, nonanoyloxybenzenesulfonate, cationic nitriles, cholyl(4-sulfophenyl)carbonate, and quaternary imine salts (e.g., N-methyl-3,4-dihydrooisoquinolinium p-toluenesulfonate).
Other bleach activators which may be used include transition metal-containing bleach catalysts such as [Mn^IV 2(µ-0)₃(Me₃TACN)₂](PF₆)₂ (as described in U.S. Patent Nos. 4,728,455, 5,114,606, 5,153,161, 5,194,416, 5,227,084, 5,244,594, 5,246,612, 5,246,621, 5,256,779, 5,274,147, 5,280,117), [Fe^II(MeN4py)(MeCN)](CIO₄)₂ (as described in EP 0 909 809) and [Co^III(NH₃)₅ (OAc)](OAc)₂ (as described in U.S. Patent No. 5,559,261, WO 96/23859, WO 96/23860, WO 96/23861). It is further noted that the bleach activators employable in this invention may be added to the aqueous machine dishwashing formulation as granulates or encapsulated granulates or both.

Enzymes

Enzymes may typically make up from 0.5wt% to 10.0wt% by weight based on the total weight of the aqueous machine dishwashing formulation, and include proteases like Savinase®, Purafect Ox®, Properase®, and Ovozyme® and amylases like Termamyl®, Purastar ST®, Purastar Ox Am®, and Duramyl®, all of which are commercially available.

Antifoaming agent

Suitable antifoaming agents include, for example, silicone antifoams, silicone oil, mono- and distearyl acid phosphates, mineral oil, and 2-alkyl and alkanol antifoam compounds. These antifoaming agents may be used in combination with defoaming surfactants. The aqueous machine dishwashing formulation typically comprises from 0.02wt% to 2wt%, preferably from 0.05wt% to 1.0wt% by weight of antifoaming agent based on the total weight of the aqueous machine dishwashing formulation.

Antitarnishing agents

Suitable anti-tarnishing agents typically comprise benzotriazole, 1,3 N-azoles, isocyanuric acid, purine compounds, and mixtures thereof.

Buffering agents

The buffering agents which may be used typically make up from 1.0wt% to 25.0wt% by weight based on the total weight of the aqueous machine dishwashing formulation and include well known buffering agents like potassium and sodium salts of disilicate, bicarbonate and carbonate.
When preparing the aqueous machine dishwashing formulation of this invention, the desired components or solutions thereof are mixed, and preferably added to a solution of a thickening agent. The order of addition of ingredients can be varied. The amount of water present in aqueous machine dishwashing formulation is typically from 15wt% to 80wt%, and preferably from 20wt% to 75wt% and most preferably from 25wt% to 70wt%, by weight based on the total weight of the aqueous machine dishwashing formulation. The thickeners which may be used in this invention include cross-linked anionic polymers. Illustrative examples include cross-linked polyacrylic acid-type thickening agents which are sold by B.F. Goodrich under their Carbopol trademark. Especially preferred are Carbopol 934, 940, 941, 980 and 981.
The amount of the high molecular weight, cross-linked polyacrylic acid or other high molecular weight, hydrophilic cross-linked polyacrylic acid-type thickening agent will generally be in the range of from 0.1wt% to 3.0wt%, and preferably, from 0.2wt% to 2.0wt% by weight based on the total weight of the aqueous machine dishwashing formulation, in order to impart the desirable rheological property of linear viscoelasticity.
Other optional additives which may be used with the preferred embodiments of this invention include well known items such as perfumes, dispersants, colorants, lime soap dispersants, inert organic molecules, enzyme stabilizers, additional builders and bleach scavengers. Such additives, collectively, do not normally make up more than about 8.0wt% by weight based on the total weight of the aqueous machine dishwashing formulation.
Mixtures of any of the above optional ingredients may be used.
In a preferred embodiment the aqueous machine dishwashing formulation of this invention is in the form of a gel, and comprises one or more, and preferably all, of the following additional ingredients: an anti-spotting agent comprising a hydrophobically modified polycarboxylic acid; a surfactant having a cloud point in water of less than about 60°C; a water soluble polymer that reduces phosphate scale formation; a compound that reduces carbonate scale formation, and an encapsulated bleach.

Packaging

Preferably the aqueous machine dishwashing formulation of the invention as described above is packaged in a water soluble sachet. As used herein, water soluble sachet is defined to mean a sachet made of a material that will dissolve, for example, in a cleaning cycle of a domestic dishwasher.
The materials that may be used to make the water soluble sachets include those which may generally be classified as water soluble resins, such as film-forming water soluble resins, either organic or inorganic.
Suitable water-soluble resins which may be used are described for example in Davidson and Sittig, Water-Soluble Resins, Van Nostrand Reinhold Company, New York (1968). The water-soluble resin should have proper characteristics such as strength and pliability in order to permit machine handling. Preferred water-soluble resins include polyvinyl alcohol, cellulose ethers, polyethylene oxide, starch, polyvinylpyrrolidone, polyacrylamide, polyvinyl methyl ether-maleic anhydride, polymaleic anhydride, styrene maleic anhydride, hydroxyethylcellulose, methylcellulose, polyethylene glycols, carboxymethylcelulose, polyacrylic acid salts, alginates, acrylamide copolymers, guar gum, casein, ethylene-maleic anhydride resin series, polyethyleneimine, ethyl hydroxyethylcellulose, ethyl methylcellulose, hydroxyethyl methylcellulose. Lower molecular weight water-soluble, polyvinyl alcohol film-forming resins are generally, preferred.
The generally preferred water-soluble, polyvinyl alcohol film-forming resins should, in addition to low weight average molecular weights, have low levels of hydrolysis in water. Polyvinyl alcohols preferred for use herein have a weight average molecular weight between about 1,000 and about 300,000, and preferably, between about 2,000 and about 150,000, and most preferably, between about 3,000 and about 100,000.
It is also possible to use polyvinyl alcohol films which are copolymers such as films prepared from vinyl acetate and methacrylic acid precursor monomers. Preferred copolymers typically comprise less than about 15.0% by weight methacrylic acid units in their backbone.
When compared to plastics, the tensile strength of polyvinyl alcohol is relatively high, and when compared with other water-soluble materials, the tensile strength of polyvinyl alcohol is extremely high. Reasonable tensile strength is required in film used in sachets for use in the present invention, in order to permit proper handling and machining. The tensile strength of polyvinyl alcohol will vary with a number of factors, including the percent hydrolysis, degree of polymerization, plasticizer content, and humidity. In a most preferred embodiment, polyvinyl alcohol is used to make the water soluble sachet.
Polyvinylpyrrolidone, another preferred resin for use to make sachets for use in the present invention, may be made from a variety of solvents to produce films which are clear, glossy, and reasonably hard at low humidities. Unmodified films of polyvinylpyrrolidone may be hygroscopic in character. Tackiness at higher humidities may be minimized by incorporating compatible, water-insensitive modifiers into the polyvinylpyrrolidone film, such as 10% of an arylsulfonamide-formaldehyde resin.
Other preferred water-soluble films may also be prepared from polyethylene oxide resins by standard calendering, molding, casting, extrusion and other conventional techniques. The polyethylene oxide films may be clear or opaque, and are inherently flexible, tough, and resistant to most oils and greases. These polyethylene oxide resin films provide better solubility than other water soluble plastics without sacrificing strength or toughness. The excellent ability to lay flat, stiffness, and sealability of water-soluble polyethylene oxide films make for good machine handling characteristics.
The weight percent of water-soluble, film-forming resin suitably ranges from 0.1wt% to 10wt%, preferably from 0.25wt% to 7.5wt%, and most preferably from 0.50w% to 5wt%, by total weight of water-soluble, film-forming resin based on the total weight of the packaged aqueous machine dishwashing formulation.
When preparing the water soluble sachets for use in the present invention, any of the art recognized techniques for making water soluble sachets may be used.
One particularly preferred method employs thermoformed packages. The thermoforming process generally involves molding a first sheet of water soluble film to form one or more recesses adapted to retain the aqueous machine dishwashing formulation of the current invention, placing the aqueous machine dishwashing formulation in at least one recess, placing a second sheet of water soluble material over the first so as to cover each recess, and heat sealing the first and second sheets together at least around the recesses so as to form one or more water soluble packages, as described in WO 00/55415.
A second route comprises vertical form-fill-seal (VFFS) envelopes. In one of the VFFS processes, a roll of water soluble film is sealed along its edges to form a tube, which tube is heat sealed intermittently along its length to form individual envelopes which are filled with the aqueous machine dishwashing formulation of the invention and heat sealed.
The size and the shape of the sachet for use in the invention are not limited and individual sachets may be connected via perforated resin. Preferably, the sachet is of the size to carry a unit dose for a domestic dishwashing machine.
When washing articles with the aqueous machine dishwashing formulation of the invention, soiled articles are is typically placed in a conventional domestic or commercial dishwashing machine, as is the aqueous machine dishwashing formulation of the invention, which is preferably in the form of a gel and is packaged in a water soluble sachet as described above. The typical dishwashing cycle is from about 10 minutes until about 60 minutes, and the typical temperature of the water in the dishwasher is from about 40°C to about 70°C. Washed glassware resulting from the above-described washing method is clean and has an excellent glass appearance (i.e., substantially free of film and spots). Such results are unexpectedly obtained even when hard water at high temperatures (greater than 55°C) is used, and in the absence of separately added rinse aid compositions.
The following Examples is provided facilitate an understanding of the present invention. The examples are not intended to limit the scope of the invention as described in the claims.

EXAMPLE

The following formulation having ingredients as listed in the Table below, represents an aqueous machine dishwashing formulation according to the invention.
The formulation as described in the above Table was prepared on an approximately 1 kg scale. This formulation was packed into water soluble polyvinyl alcohol sachets. Each sachet contained 27 gm of the formulation. These sachets were then individually packed into plastic bags, the bags closed and stored at constant temperature conditions of 37 degrees C. Sachets were then withdrawn at periodic intervals and analysed for tripolyphosphate, orthophosphate and pyrophosphate concentration which were used to calculate the percentage breakdown.
The formulation had a significantly reduced rate of phosphate breakdown in comparison to a control formulation which differed from it only in the omission of the monoethanolamine.

Claims

An aqueous machine dishwashing formulation comprising at least 10wt% water, a tripolyphosphate builder material and from 0.01 to 3.5wt% of an organic amine compound.
A formulation according to claim 1, in which the tripolyphosphate builder material is potassium tripolyphosphate.
A formulation according to claim 1 or claim 2, in which the organic amine compound is monoethanolamine.
A formulation according to any preceding claim, which is in the form of a gel, and comprises one or more of the following additional ingredients: an anti-spotting agent comprising a hydrophobically modified polycarboxylic acid; a surfactant having a cloud point in water of less than about 60°C; a water soluble polymer that reduces phosphate scale formation; a compound that reduces carbonate scale formation, and an encapsulated bleach.
A formulation according to any preceding claim which is packaged in a water-soluble sachet.