EP1113070A2 - Automatic dishwashing compositions comprising MGDA having low alkalinity - Google Patents

Abstract

A mechanical dishwasher rinsing agent contains, as complexing agent, methyl glycine diacetic acid (I) (or one of its salts), the rinsing agent has pH not more than 10.4 (preferably 6-10.4) as a 0.5% aqueous solution. Use of (I) (or its salt) is claimed as partial or complete substitute for builders or complexing agents in such rinsing agents in order to improve removal of milk and tea residues.

Description

The invention relates to machine dishwashing detergents Alkalinity, methylglycinediacetic acid (MGDA) or a salt of which contain and which preferably have a reduced content of Have bleach.

Highly alkaline dishwasher detergent without bleach with a high proportion of complexing agents are in the state known in the art. They were sold in the past as a means for household dishwashers and still today they are used for industrial devices.

US-A 3 673 098 discloses caustic compositions without Bleaching agents based on KOH and nitrilotriacetic acid (NTA) based.

Fr-A 1 590 416 also discloses caustic compositions without bleach based on alkali hydroxides, Pyrophosphates and NTA based.

Such agents later became without caustic alkalis was formulated, and the loss of performance was added by of chlorine bleach, as exemplified in US-A-3,826,748 is balanced. This means without caustic Alkaline still had a high pH greater than 11.

The trend towards safer and more environmentally friendly means initially led to the replacement of strong complexing agents through builder and later to a new generation of mild alkaline dishwashing detergents with a pH of 9 to 11.5, whose chlorine bleaching by oxygen bleaching and enzymes have been replaced.

Good examples of such means can be found in the EP-A-135 226, EP-A-135 227 and EP-A-414 197. Bei These agents are usually complexing agents if at all, only available in small quantities.

EP-A-530 635 discloses acidic to mildly alkaline Compositions (pH 5-9) that do not contain complexing agents contain and on builders, enzymes and optionally Oxygen bleaching is based.

DE-A-3 833 047 discloses acidic compositions (pH 2-6) with hydrolases and builders or complexing agents. The Examples disclose high NTA or EDTA share (up to 30%). While these compositions can e.g. Eliminate tea residues well, there is milk residue their effect, measured on a scale from 0 to 10, however always under 5.

The use of other biodegradable complexing agents, such as β-alanine diacetic acid (β-ADA) and iso-serine diacetic acid (ISDA), in detergents is in the DE-A-3 829 847 and DE-A-4 036 995. If those Publications Application examples for dishwasher detergents contained, it is machine dishwashing detergent, which in about 0.5% aqueous solution has a pH of more than 10.5.

In addition, these connections work much less complexing as NTA and can do this in the finished Only insufficiently replace funds.

DE-A-4 319 935 describes the use of MGDA in Dishwasher detergents disclosed without an example specify. In a GDCH lecture on May 30, 1995 published one of the inventors of DE-A-4 319 935 Use of methylglycinediacetic acid (MGDA) as Complexing agent for cleaning equipment parts of the Dairy industry on an industrial scale and in Dishwashing detergents with a pH in solution of more than 10.5.

The same information can also be found in the "Preliminary technical Information, Trilon® ES 9964 ", April 1995, from BASF AG be removed. The dishwashers disclosed there contain 5-30% MGDA and 1.12% active oxygen, with MGDA in the inhibition of deposits (formation of calcium carbonate deposits) achieved a result comparable to that of NTA. The effectiveness of dishwashers on milk residues or Tea residues are not mentioned. MGDA is said to be at Dissolve calcium phosphate residues better in dairy cleaning as an NTA. Dairy cleaning is usually done in strongly alkaline range worked.

In an article in SÖFW Journal 122, 1996, 392 the Use of MGDA in laundry detergents suggested. MGDA is supposed to be a better one, especially for blood-soiled laundry Have effect, as phosphonates and with tea soiled Laundry have about the same effect as phosphonates. The same publication discloses that MGDA in a dishwashing detergent, similar to NTA, a very good one Deposit inhibition on glass, metal and porcelain shows, whereby a dishwashing detergent is disclosed which in solution provides pH of more than 10.5. It will too suggested MGDA in very strongly alkaline conditions to use for dairy cleaning.

The previously proposed machine dishwashing liquid, the Use complexing agents therefore have the disadvantage that they either work at higher pH values or none sufficient cleaning power for certain food residues, especially for milk residues and tea residues, exhibit.

It is an object of the invention to provide a dishwasher detergent to provide that not only works at a low pH but beyond also removes food remnants that are difficult to remove usually working at such a pH Dishwasher detergent unsatisfactory remove. In particular, such a dishwashing detergent excellent cleaning performance for dishes have both milk and milk Tea residue is contaminated. This task is accomplished by a Dishwasher detergent dissolved, the methylglycinediacetic acid or their salts as complexing agents and is characterized in that it is approximately 0.5% aqueous solution does not exceed a pH of 10.4.

Milk residues consist of a mixture of denatured proteins (casein), fats, sugars and mineral deposits and consist of around 70% calcium phosphate (Ca ₃ (PO ₄ ) ₂ ). Complexing agents therefore have a significant influence on the removal of milk residues because they dissolve calcium phosphates by complexing the calcium ions.

Tea residues are also based on Ca deposits, that arise when brewing tea with hard water. However, tea residues are usually different Requirements for a dishwasher detergent as Milk residues, which can be seen from the fact that the detergent disclosed in DE-A 3 833 047 in the acidic range (pH 2-6) Tea residues removed satisfactorily, at Milk residues cannot convince.

The ability (based on the weight of the complexing agent) to complex calcium ions at a certain pH value depends on the stability constant of the calcium complex (pK _c ), the acidic character of the complexing agent (pK ₃ ) and its molecular weight.

Although MGDA for calcium carbonate at pH 11 has a higher theoretical degree of complexation than NTA (as disclosed in the aforementioned GDCH lecture and what can be calculated theoretically) results at pH 7 and 10.4 and for calcium phosphates different result.

In fact, the theoretical is at pH 10.4 Degree of complexation for calcium phosphates when using NTA at 360 mg / g and when using MGDA at 340 mg / g, and at pH 8 the theoretical values are 510 mg / g for NTA and 490 mg / g for MGDA.

Therefore, based on these theoretical considerations, it follows that MGDA for a dishwashing detergent that is approximately 0.5% aqueous solution provides a pH of less than 10.4 has a less complexing effect on calcium phosphates and thus Milk residues should be removed worse than that common NTA.

In the prior art, MGDA was only used in dishwashing detergents used in about 0.5% aqueous solution have a pH of more than 10.4.

At lower pH values, the use of NTA on that better at such pH values on calcium phosphates should have a complexing effect as MGDA and also in acid Range (pH 2-6) Tea residues removed satisfactorily (DE-A 38 33 047).

According to the invention, however, it was surprisingly found that Dishwashing detergents that contain MGDA and one of them 0.5% aqueous solution with a pH of up to 10.4 deliver better both tea residues and milk residues can remove and overall a better washing result have as dishwashing detergent, which instead of MGDA another Contain complexing agents such as the common NTA.

It was also surprisingly found that one Dishwashing detergent according to the invention, the sufficient Amount of complexing agent MGDA has the amount of Oxygen bleach can be reduced without changing thereby the flushing performance and in particular the ability Remove milk residues and tea residues, worsened. This surprising finding even opens up the possibility of using a sufficiently large amount of complexing agents completely on the use of To avoid oxygen bleach.

The dishwashing detergent according to the invention can be liquid or be powdery and also in the form of a single layer or multi-layer tablet. Appropriate Dosage forms and methods of obtaining them are the Known specialist.

The dishwasher detergents according to the invention preferably contain one or more enzymes such as Amylase, protease, lipase or cellulase. Through the combined application of amylase and protease were the best cleaning results. The ones here These enzymes are particularly suitable for the pH ranges described use effectively; for example, the temperature stable amylase Termamyl (Novo) at pH 7-8 das Optimal of your spectrum of activity. The enzymes come in Granulate form or in solution with commercially available Concentrations or activities are used, the Enzyme content is 0.5-6, preferably 1-4% by weight can.

Examples of suitable builders are homo- and copolymers Polycarboxylic acids and their partially or completely neutralized salts, monomeric polycarboxylic acids and Hydroxycarboxylic acids and their salts, carbonates, bicarbonates, Borates, phosphates, silicates, aluminosilicates and mixtures such substances.

Preferred salts of the above compounds are the ammonium and / or alkali salts, i.e. the lithium, Sodium, potassium and rubidium salts and particularly preferred the sodium salt used.

Suitable polycarboxylic acids are.acyclic, alicyclic, heterocyclic and aromatic carboxylic acids, these contain at least two carboxy groups, each through preferably no more than two carbon atoms from each other are separated.

Polycarboxylates containing two carboxy groups include for example water-soluble salts of succinic acid, Malonic acid, (ethylenedioxy) diacetic acid, maleic acid, Diglycolic acid, tartaric acid, tartronic acid and fumaric acid. Polycarboxylates containing three carboxy groups include for example, water-soluble citrates. Corresponding is suitable as a hydroxycarboxylic acid, for example Citric acid.

genannt werden.As a special builder for dishwasher detergents, one of aspartic acid can also be used HOOC-CH (NH ₂ ) -CH ₂ -COOH derived polymer with monomer units of the formula

to be named.

The homopolymer of is also suitable as the polycarboxylic acid Acrylic acid.

In addition to borates such as sodium borate, borate builders can also such builders are used, the borates among the Detergent storage conditions or rinsing conditions release.

Suitable phosphates are polyphosphates such as tripolyphosphate, Pyrophosphate, orthophosphate and the polymeric metaphosphate. For example, alkali tripolyphosphates, sodium, Potassium and ammonium pyrophosphate, sodium and potassium orthophosphate as well as sodium polymetaphosphate, wherein the degree of polymerization preferably ranges from 5 to 21.

Suitable silicates are sodium silicates such as sodium disilicate, Sodium metasilicate and crystalline layered silicates. Sodium aluminosilicates are also suitable (Zeolite).

Further suitable builders are described in WO 95/01416 hereby expressly refers to the content thereof is taken.

A builder system from the salt of one is particularly preferred Hydroxycarboxylic acid or from the mixture of one Hydroxycarboxylic acid and the salt of a hydroxycarboxylic acid. Both the hydroxycarboxylic acid and the salt of Hydroxycarboxylic acid can be completely or partially Tripolyphosphate can be replaced, although this is not preferred becomes.

The builder system preferably consists of a Hydroxypolycarboxylic acid with 2-4 carboxyl groups (or acidic inorganic salts), which are used to adjust the pH value with their Salt can be mixed. Citric acid is preferred or a mixture of sodium citrate with citric acid used. To adjust the invention The required pH value is suitable depending on the others Components of the mixture e.g. Mix with one predominant proportion of citric acid.

The water content of liquid dishwashing detergent can be 40-80 % By weight.

The liquid dishwashing detergents also contain 0.2-5.0% by weight, preferably 0.5-2% by weight, of a thickener. High-molecular organic polymers with molecular weights of 5 × 10 ⁵ to approx. 5 × 10 ⁶ , which are made up of olefinically unsaturated carboxylic acids, are suitable as thickeners. Carboxyvinyl polymers, such as those marketed by BF Goodrich under the production name "Carbopol", proved to be very useful. Inorganic compounds which have thickening properties in this product composition can also be used. Examples of this are natural or synthetic thickeners based on differently structured silicate structures. Their use is described in various patents, for example in US-A-4 933 101 or EP-A2-0 407 187.

For example, nonionic surfactants are suitable as surfactants. These include, for example, water-soluble ethoxylated C _6-16 fatty alcohols and C _6-16 mixed ethoxylated / propoxylated fatty alcohols and mixtures thereof, and also polyglucosides.

Another class of non-ionic surfactants includes polyhydroxy fatty acid amides.

Further suitable surface-active agents are described in WO 95/01416, the content of which is hereby expressly disclosed Reference is made.

The dishwasher detergent according to the invention can further contain one or more foam control agents. All those used in this area are suitable for this Foam control agents such as silicones and Paraffin oil.

The foam control agents are in the invention Machine dishwashing detergent preferably with less than 5% by weight of the total weight of the detergent.

The machine dishwashing detergents according to the invention can be used as Bleaching agents prefer chlorine-free, active oxygen releasing bleaches such as inorganic perhydrates or contain organic peracids and their salts.

Examples of inorganic perhydrates are perborates, Percarbonates and persulfates such as peroxymonopersulfate. The inorganic perhydrates are usually alkali metal salts, such as lithium, sodium, potassium or rubidium salts, especially the sodium salts. The inorganic perhydrates can in the detergent as crystalline solids without protection. For certain perhydrates however, it is advantageous to use them as granular To use compositions with a coating are provided, the better the granular products Gives storage stability.

The preferred perborate is sodium perborate, which can be present as a monohydrate with the formula NaBO ₂ H ₂ O ₂ or as a tetrahydrate with the formula NaBO ₂ H ₂ O ₂ .3H ₂ O.

The preferred percarbonate is sodium percarbonate with the formula 2Na ₂ CO ₃ 3H ₂ O ₂ . The percarbonate is preferably used in a coated form to increase its stability.

Organic peracids all conventionally include bleaching agents used organic peracids, including for example perbenzoic acid and peroxycarboxylic acids such as Mono- or diperoxyphthalic acid, 2-octydiperoxysuccinic acid, Diperoxydodecanedicarboxylic acid, Diperoxyazelaic acid and Imidoperoxycarboxylic acid and optionally its salts.

The dishwasher detergent according to the invention can continue to contain one or more bleach activators. These are preferred in detergents for dishwashing operations at temperatures below 60 ° C used to achieve a sufficient bleaching effect. N- and O-acyl compounds, for example, are particularly suitable such as acylated amines, acylated glycolurils or acylated sugar compounds. To be favoured N, N, N ', N'-tetraacetylethylenediamine (TAED), pentaacetylglucose (PAG) and tetraacetylglycoluril (TAGU). Are also suitable but also catalytically active metal complexes and preferred Transition metal complexes as bleach activators. The most TAED is preferred.

Further suitable bleach activators are described in WO 95/01416 hereby expressly refers to the content thereof is taken.

By using MGDA at relatively low However, the use of bleaching agents can reduce pH values are and preferably have the invention Dishwasher detergent is an oxygen bleach an amount of less than 1% by weight, based on the active Oxygen on. The amount of bleach activator used will be adjusted accordingly.

In one embodiment, the machine dishwashing detergents a large percentage of MGDA, like 25% or more, preferably 30% or more, in each case based on the free acid, and an oxygen bleach is not used.

The dishwasher detergent according to the invention can also contain a silver / copper anti-corrosion agent. This term includes funds that start up Non-ferrous metals, especially silver and copper, prevent or mitigate. Preferred silver / copper anti-corrosion agents are benzotriazole or bis-benzotriazoles as well as their substituted derivatives.

Other suitable agents are organic and / or inorganic redox-active substances and paraffin oil.

Benzotriazole derivatives are those compounds in which the available substitution sites of the aromatic ring are partially or completely substituted. Linear or branched chain C _1-20 alkyl groups as well as hydroxy, thio, phenyl or halogen such as fluorine, chlorine, bromine and iodine are suitable as substituents. Preferred substituted benzotriazole is tolyltriazole.

Suitable bis-benzotriazoles are those in which the benzotriazole groups are each connected in the 6-position by a group X, in which X is a bond, a straight-chain alkylene group which is optionally substituted by one or more C _1-4 alkyl groups and preferably has 1-6 carbon atoms , a cycloalkyl radical having at least 5 carbon atoms, a carbonyl group, a sulfuryl group, an oxygen or a sulfur atom. The aromatic rings of the bis-benzotriazoles can be substituted as defined above for the benzotriazole.

Suitable organic redox-active substances are, for example, ascorbic acid, indole, methionine, an N-mono- (C ₁ -C ₄ alkyl) glycine, an N, N-di (C ₁ -C ₄ alkyl) glycine, 2- phenylglycine or a coupler and / or developer compound chosen from the group of diaminopyridines, aminohydroxypyridines, dihydroxypyridines, heterocyclic hydrazones, aminohydroxypyrimidines, dihydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, Diaminodihydroxypyrimidine, Dihydroxynaphtaline, naphthols, pyrazolones, hydroxyquinolines, aminoquinolines, primary aromatic amines, which in ortho, meta or para position have a further free or with C ₁ -C ₄ alkyl or C ₂ -C ₄ hydroxyalkyl groups substituted hydroxy or amino groups and the di- or trihydroxybenzenes.

Suitable inorganic redox-active substances are for example, metal salts and / or metal complexes selected from the group of manganese, titanium, zirconium, hafnium, Vanadium, cobalt and cerium salts and / or complexes, wherein the metals in one of the oxidation states II, III, IV, V or VI are available.

Metal salts and / or metal complexes selected from the group MnSO ₄ , Mn (II) citrate, Mn (II) stearate, Mn (II) acetylacetonate, Mn (II) - [1-hydroxyethane-1,1 are particularly suitable diphosphonate], V ₂ O _5, V ₂ O _4, VO _2, TiOSO _4, K ₂ TiF _6, K ₂ ZrF _6, CoSO _4, Co (NO _{3) 2,} Ce (NO _{3). 3}

Organic and inorganic redox-active substances, which as Silver / copper anti-corrosion agents are suitable also mentioned in WO 94/26860 and WO 94/26859, on the Content hereby referred.

Suitable paraffin oil are predominantly branched aliphatic hydrocarbons with a number of carbon atoms in the range from 20 to 50. The paraffin oil is preferably selected from predominantly branched chain C _25-45 species with a ratio of cyclic to noncyclic hydrocarbons of 1:10 to 2: 1 , preferably from 1: 5 to 1: 1.

If a silver / copper anticorrosive in the machine dishwashing detergent according to the invention is present, it is preferably 0.01 to 5% by weight, particularly preferably with 0.1 to 2 wt .-% of the total weight.

In the embodiment of the invention in which the proportion of MGDA on the dishwasher detergent is high enough, such as 25% or more, preferably 30% or more, each based on is the free acid, so that there is no bleaching agent can also be used on a silver / copper anti-corrosion agent to be dispensed with.

Other common additions are e.g. Dyes and fragrances and if necessary preservatives for liquid products, why e.g. Isothiazolinone based compounds are suitable.

The machine dishwashing detergents according to the invention are not caustic and therefore do not require a specially secured one Packaging. A good washing result can be achieved with one relatively low use of 15-20 g powder or 20-50 ml of liquid detergent can be achieved. All ingredients are according to current knowledge, neither toxic nor otherwise harmful to health. The cleaning agents described here therefore also represent an environmentally and consumer-friendly Alternative to conventional cleaners with Complexing agents in the strongly basic area work.

The methylglycinediacetic acid used according to the invention has the following structural formula:

Methylglycinediacetic acid is particularly preferred as free acid or used as sodium or potassium salt and is preferably in an amount of 3% to 90%, based on the free acid, contained in the detergent.

In bleach-free dishwasher detergents that are Phosphates as the main component of the builder system based, the amount of MGDA is preferably at least 5%, based on the free acid.

According to the invention it is essential that an approximately 0.5% aqueous solution of the detergent has a pH of no more than 10.4. The pH is preferably about 0.5% aqueous solution of the detergent according to the invention more than 6 to 10.4, particularly preferably from 7 to 10.0.

The following comparison test proves that the in the article in the SÖFW Journal 122, 1996, 392-397 Dishwashing detergent in 0.5% aqueous solutions have a pH value of more than 10.4. The revelation of this Article is therefore in line with the theoretical Expectation that MGDA will occur at pH greater than 10.4 is excellent complexing agent, at pH values of 10.4 or but is inferior to the usual NTA.

Comparison test

Natriumcitratdihydrat

Natriumcarbonat

Natriumhydrogencarbonat

Natriumperboratmonohydrat

TAED

C₁₃C₁₅ Oxoalkohol + 4 Mol PO + 2 Mol EO

MGDA (Trinatriumsalz von Methylglycindiessigsäure) (77%-ige Lösung in Wasser) = TRILON ES 9964 erhältlich von der BASF-AG Die nachstehende Tabelle zeigt die Mengen der jeweiligen Bestandteile in g und %. Die Bestandteile wurden in einem Liter Wasser von 10° Härte gelöst, und der pH-Wert der Lösung wurde jeweils bestimmt. Die Gesamtmenge der Bestandteile (100%) beträgt jeweils 4 g, entsprechend einer 0,4%-igen Konzentration, wie sie in Figur 14 des Artikels offenbart ist.In accordance with the disclosure of the article in SÖFW-Journal 122, 1996, 392-397, dishwashing detergents are made from the following ingredients:

Sodium citrate dihydrate

sodium

Sodium bicarbonate

Sodium perborate monohydrate

TAED

C ₁₃ C ₁₅ oxo alcohol + 4 moles PO + 2 moles EO

MGDA (trisodium salt of methylglycinediacetic acid) (77% solution in water) = TRILON ES 9964 available from BASF-AG The table below shows the amounts of the respective constituents in g and%. The components were dissolved in one liter of water of 10 ° hardness, and the pH of the solution was determined in each case. The total amount of ingredients (100%) is 4 g each, corresponding to a 0.4% concentration as disclosed in Figure 14 of the article.

MGDA is not commercially available in its pure form and therefore a 77% solution in water was used. A larger amount of the commercially available product had to be used, as shown in the table. Two values are given in the table for MGDA. The first value indicates the amount in g of the commercial product, and the second value corresponds to the corresponding amount of pure substance (100%). SÖFW Journal 122, 1996, 392-397 Ex. 1 Ex. 2
Quantities in g. (%) Ex. 3 Citrate 2 (50%) 1.6 (40%) 1 (25%) Carbonate 1 (25%) 1 (25%) 1 (25%) Hydrogen carbonate 0.36 (9%) 0.36 (9%) 0.36 (9%) Perborate 0.28 (7%) 0.28 (7%) 0.28 (7%) TAED 0.08 (2%) 0.08 (2%) 0.08 (2%) non-ionic 0.08 (2%) 0.08 (2%) 0.08 (2%) surface active medium MGDA 0.26 / 0.2 (5%) 0.78 / 0.6 (15%) 1.56 / 1.2 (30%) (77% sol.) / (100%) total 4.06 4 4.18 4 4.36 4 pH 10.64 10.79 10.82

Although the pH of 0.5% solutions of the agent is not was determined directly, the pH was 0.4% Solutions determined. At a higher concentration of the Detergent solutions are a matter of course the same or, more likely, higher pH values exhibit.

The following example shows that when replacing part of the builder of a dishwasher detergent with methylglycinediacetic acid at low pH values excellent washing performance can be achieved and especially contrary to theoretical expectations Ability to remove milk residues and tea residues higher than other common complexing agents such as NTA. The example illustrates the invention.

example

Liquid dishwashing detergents with a Composition as shown in Table 1 is made (both according to the invention using MGDA and using the NTA used in the prior art), and their washing performance was measured using dishes that both Contained milk and tea residues, determined. In this Test was essentially the DIN standard No. 44990, part 2 followed. It became a Bosch SMS 5062 dishwasher used. The water had a hardness of 19 ° dH (3.39 mmol Calcium carbonate), the temperature of the water was 65 ° C and 20 ml of detergent were used in each case. The results The flushing performance was assessed on a scale of 1-5 (5 for 100% clean dishes are rated) and are also listed in Table 1.

The non-ionic surfactant is a common, low-foaming ethoxylated and propoxylated fatty alcohol. Common proteases and amylases are used.

From the results of Table 1 it can be seen that in a pH range below 10.4 detergents containing MGDA, surprisingly both in the removal of Milk residues as well as in the removal of Tea residues get better results than that appropriate detergent, which is the usual instead of MGDA NTA included.

Claims (4)

Dishwasher detergent containing methylglycinediacetic acid or their salts as complexing agents, characterized in that the agent in about 0.5% aqueous solution does not exceed a pH of 10.4. Machine dishwasher detergent according to claim 1, characterized characterized in that it is an oxygen bleach in a Amount less than 1% active based on weight Contains oxygen. Dishwasher detergent according to claim 1 or 2, characterized in that the agent in about 0.5% aqueous solution has a pH of 6 to 10.4. Use of methylglycinediacetic acid or its salts as a full or partial replacement for Builder or Complexing agents in machine dishwashing detergents a pH of not more than 10.4 in about 0.5% aqueous solution to improve ability both Eliminate milk residues as well as tea residues.