ES2300287T3 - LOW ALKALINITY DETERGENTS FOR DISHWASHERS WITH METHYLGLYCINDITIC ACID (MGDA) CONTENT. - 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

Low alkalinity detergents for dishwasher containing methylglycylacetic acid (MGDA)

The invention relates to low detergents alkalinity for dishwashers comprising acid methylglycostatic acid (MGDA), or one of its salts, and that have preferably a reduced content of bleaching agent.

Highly alkaline and free detergents bleaching agent for dishwashers, which have a high content of complexing agents, are known in the prior art. At Lastly, they were sold as household dishwashing compositions and are still currently used for industrial equipment.

The US Patent Publication US-A-3,673,098 describes Caustic bleaching agent-free compositions that are based on KOH and nitrilotriacetic acid (NTA).

French patent publication FR-A-1,590,416 also describes Caustic bleaching agent-free compositions that are based on alkali metal hydroxides, pyrophosphates and NTA.

Such compositions were subsequently formulated. without caustic alkalis, and the loss of performance was compensated adding a chlorine bleaching agent, as described, by example, in the US patent publication US-A-3,826,748. These compositions without caustic alkalis they still had a high pH higher than eleven.

The trend towards safer compositions and environmentally friendly initially led to substitution of strong complexing agents by reinforcers and later to a new generation of mildly alkaline detergents with a pH of 9 to 11.5, for dishwashers, in which chlorine bleach is replaced by oxygen bleach and enzymes.

You can find good examples of such compositions in the documents EP-A-135,226, EP-A-135,227 and EP-A-414,197. In these compositions, normally complexing agents are only present in small quantities, if they are.

The document EP-A-530.635 describes compositions from acidic to mildly alkaline (pH 5-9) that does not They comprise complexing agents and are based on enhancers, enzymes and, optionally, oxygenated bleach.

German patent publication DE-A-3,833,047 describes acidic compositions (pH 2-6) containing hydrolases and reinforcing agents or complexing agents. The examples describe compositions with a high content of NTA or EDTA (up to 30%) Although these compositions can be easily removed, by example, tea waste, its effect in the case of milk waste, measured on a scale of 0 to 10, it is always below 5.

The use of other complexing agents biodegradable, such as acid β-alanindiacetic (β-ADA) and isoserindiacetic acid (ISDA), in detergents, described in German patent publications DE-A-3,829,847 and DE-A-4,036,995. Where are you publications include examples of detergent application for dishwasher, said dishwashing detergents have, in aqueous solution of concentration approximately 0.5%, a pH greater than 10.5.

In addition, these compounds have an action complexing significantly lower than the NTA, and they are just a Poor replacement for the latter in the finished composition.

German patent publication DE-A-4,319,935 describes the use of MGDA in dishwashing detergents without giving an example. In a conference of the GDCH (Association of German Chemists) on 30 May 1995, one of the inventors of the German patent DE-A-4,319,935 published the use of Methylglycineacetic acid (MGDA) as a complexing agent for cleaning equipment in the dairy industry on an industrial scale, and in dishwashing detergents that have a solution pH greater than 10.5

You can also find the same information in "Preliminary Technical Information, Trilon® ES 9964", April 1995, from BASF AG. The dishwashing detergents described there they comprise 5-30% of MGDA and 1.12% of active oxygen, achieving the MGDA a result comparable to the NTA in the inhibition of the inlay (formation of calcium carbonate deposits). Do not the effectiveness of dishwashing detergents on milk residues or tea residues. However, the MGDA should be much more capable of dissolving calcium phosphate residues than NTA during dairy cleaning. During dairy cleaning, the Work interval is usually strongly alkaline.

In an article in the magazine SÖFW [Soaps, Oils, Fats and Waxes, from German Seifen, Öle, Fette, Wachse] 122, 1996, 392, the use of MGDA in detergents for wash. Particularly in the case of blood stained laundry, it states that MGDA has a better effect than phosphonates and, in the tea stained laundry case, it has about the same effect than phosphonates. The same publication describes that the MGDA, in a dishwashing detergent, similar to NTA, exhibits a very good inhibition of embedding on glass, metal and porcelain, a dishwashing detergent being described which, in solution, produces a pH higher than 10.5. It is also proposed to use MGDA in extremely strong alkaline conditions for Dairy cleaning

The proposed dishwashing detergents to date, they use complexing agents, therefore have the disadvantage that they are effective at a relatively high pH or they don't have enough detergency capacity for certain waste foodstuffs, in particular for milk residues and residues of tea.

An object of the invention is to provide a dishwashing detergent that is effective not only at a low pH, but also eliminate waste food difficult to remove, to which dishwashing detergents, effective to such pH, they are usually unable to remove satisfactorily. In particular, such a dishwashing detergent should have a excellent detergency in the case of stained tableware with both milk residues or also with tea residues. This item is achieved. by means of a dishwashing detergent comprising sodium salt or potassium methylglynediacetic acid as a complexing agent and which is characterized in that, in aqueous solution of concentration approximately 0.5%, does not exceed a pH of 10.4, containing the dishwashing detergent an oxygenating bleaching agent in a amount less than 1% based on the weight of active oxygen.

Milk waste is made up of a mixture of denatured proteins (casein), fats, sugars and mineral deposits, and consist of approximately 70% phosphate of calcium (Ca 3 (PO 4) 2). The agents complexing agents thus have an essential influence on the elimination of milk residues because they dissolve phosphates from Calcium complexing calcium ions.

Also, tea residues are based, between others, in Ca deposits, which are formed when tea is prepared using hard water However, tea residues usually have different demands of dishwashing detergent than milk waste, something that is immediately evident from the fact of that the detergent described in the German patent publication DE-A-3,833,047 removes satisfactorily tea residues in the acidic range (pH 2-6), but it is not convincing in the case of waste milk.

Capacity (based on agent weight complexing) to complex calcium ions at a certain pH depends of the stability constant of the calcium complex (pKc), of acidic nature of the complexing agent (pK3), and its weight molecular.

Although, at a pH of 11, MGDA has a grade theoretical greater complexation for calcium carbonate than NTA (as described in the GDCH conference above mentioned, and which can be calculated theoretically), at a pH of 7 and 10.4 and for calcium phosphates, the result is different.

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

According to these theoretical considerations, it follows therefore the MGDA has a poorer complexing action on calcium phosphates in the case of a dishwashing detergent that, in aqueous solution of concentration approximately 0.5%, produces a pH less than 10.4, and thus should be less able to Eliminate milk residues than the conventional NTA.

Also, MGDA was used in the prior art. only in dishwashing detergents that have, in aqueous solution of concentration approximately 0.5%, a pH greater than 10.4.

At a lower pH, the use of NTA is preferable, which must have a better complexing action than the MGDA on calcium phosphates at such pH, and also successfully eliminates tea residues in the acidic range (pH 2-6) (document DE-A-3,833,047).

However, surprisingly it has been found according to the invention that dishwashing detergents comprising MGDA and producing an aqueous solution of concentration approximately 0.5% with a pH of up to 10.4, are more capable of eliminate tea residues and also milk residues and, in short, they have better detergency than dishwashing detergents than they comprise another complexing agent instead of MGDA, such as the NTA conventional.

Surprisingly, it has also been discovered that for a dishwashing detergent according to the invention, which has a sufficient amount of MGDA complexing agent, the amount of oxygen bleach can be reduced without weakening the detergency and in particular the ability to remove waste from Milk and tea waste. This surprising finding even opens the possibility of completely giving up the use of bleach oxygenated when using a sufficiently large amount of complexing agent

The dishwashing detergent according to the invention it can be liquid or powdery, and it can also be in shape of a single layer or multilayer tablet. The ways and methods of Corresponding dosages for their preparation are known for The person skilled in the art.

Dishwashing detergents according to invention preferably comprise one or more enzymes, such as, for example, amylase, protease, lipase or cellulase. The best cleaning results are obtained by the combined use of amylase and protease For the pH ranges described here, these enzymes are they can use particularly effectively; in this way, by example, Termamyl (Novo) amylase, stable at temperature, achieves the optimum of its spectrum of activity at pH 7-8. The enzymes are used in granular form or in solutions that have usual concentrations or activities in commerce, being possible that the content of the enzymes be 0.5-6% by weight, preferably 1-4% by weight.

Examples of suitable reinforcers are acids. homopolymer and copolymer polycarboxylic acids, and their partial salts or completely neutralized, polycarboxylic acids and acids hydroxycarboxylic monomers and their salts, carbonates, bicarbonates, borates, phosphates, silicates, aluminosilicates and mixtures of such substances

Preferred salts of the compounds before mentioned are the salts of ammonium and / or alkali metals, it is say lithium, sodium, potassium and rubidium salts, and so Especially preferred sodium salt.

Suitable polycarboxylic acids are acids acyclic, alicyclic, heterocyclic and aromatic carboxylic acids, in in which case they contain at least two carboxy groups that are in each case separated from each other preferably by no more than two carbon atoms

Polycarboxylates comprising two groups carboxy include, for example, water soluble salts of acid succinic, malonic acid, diacetic (ethylenedioxy) acid, maleic acid, diglycolic acid, tartaric acid, tartronic acid and fumaric acid. Polycarboxylates containing three groups carboxy include, for example, water soluble citrates. Likewise, a suitable hydroxycarboxylic acid is, for example, the citric acid.

It will also be mentioned as a specific reinforcer for dishwashing detergents, a polymer derived from acid aspartic

HOOC-CH (NH2) - CH2 -COOH

which contains monomer units of formula

one

It is also suitable as polycarboxylic acid the homopolymer of acrylic acid.

The borate boosters that can be used are also, in addition to borates such as sodium borate, those boosters that release borates in storage conditions of the detergent or in the washing conditions.

Suitable phosphates are polyphosphates, such such as tripolyphosphate, pyrophosphate, orthophosphate and metaphosphate polymer. Examples that can be mentioned are tripolyphosphates alkali metal, sodium pyrophosphate, potassium and ammonium, sodium and potassium orthophosphate, and sodium polymetaphosphate, being preferably the degree of polymerization therein from 5 to 21.

Suitable silicates are sodium silicates such as sodium disilicate, sodium metasilicate and crystalline phyllosilicates. Also suitable are aluminosilicates of sodium (zeolites).

Other suitable reinforcers are described in the WO 95/101416, whose contents are referred to herein express.

Particular preference is given to a system salt booster of a hydroxycarboxylic acid or mixture of a hydroxycarboxylic acid and the salt of an acid hydroxycarboxylic. Both hydroxycarboxylic acid and salt of the hydroxy carboxylic acid can be substituted completely or partially by tripolyphosphate, although this is not preferable.

The reinforcing system preferably consists of a hydroxypolycarboxylic acid containing 2-4 carboxyl groups (or acidic inorganic salts), which can be mixed with its salt to adjust the pH. Preferably citric acid is used or a mixture of sodium citrate with citric acid. To adjust the pH required according to the invention are suitable, for example, mixtures which have a major proportion of citric acid, depending on the other constituents of the mixture.

The water content of detergents Liquid dishwasher can be 40-80% by weight.

Liquid dishwashing detergents comprise in addition 0.2-5.0% by weight, preferably 0.5-2% by weight of a thickening agent. The agents Suitable thickeners are high molecular weight organic polymers having molecular weights of 5 x 10 5 to about 5 x 10 6, which are composed of olefinically carboxylic acids unsaturated Carboxyvinyl polymers, such as commercially available, for example, from B.F. Goodrich with the name of "Carbopol" manufacturing, have proven highly suitable. Inorganic compounds having properties can also be used. thickeners for this product composition. His examples are agents natural or synthetic thickeners based on different structures silicate Its use is described in various patents, for example, in the US patent US-A-4,933,101 or the document EP-A2-0.407.187.

Suitable surfactants are, by For example, non-ionic surfactants. These include, by example, C 6-16 fatty acid alcohols water soluble ethoxylates and mixed fatty acid alcohols C 6-16 ethoxylated, propoxylated, and mixtures thereof, and also polyglycosides.

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

Other suitable surfactants are described in WO 95/01416, to the contents of which It makes express reference here.

The dishwashing detergent according to the invention may also comprise one or more control agents of the foam. The foam control agents suitable for this end are all those used in this field, such as, for example, silicones and paraffin oil.

The foam control agents are preferably present in the dishwashing detergent according to the invention in amounts less than 5% by weight of the total weight of the Detergent.

Dishwashing detergents according to invention may comprise, as bleaching agent, bleach which are preferably chlorine free and release active oxygen, such as inorganic perhydrates or organic peracids and their you go out.

Examples of inorganic perhydrates are perborates, percarbonates and persulfates such as peroximonopersulfate. Inorganic perhydrates are normally alkali metal salts, such as lithium salts, sodium, potassium or rubidium, in particular sodium salt. Perhydrates inorganic may be present in the detergent as solids lenses without additional protection. For certain perhydrates, without However, it is advantageous to use them as granular compositions provided with a coating that gives granular products a longer period

The preferred perborate is sodium perborate, which can be in the form of the monohydrate, which has the formula NaBO 2 H 2 O 2, or in the form of the tetrahydrate of the formula NaBO_2H2 {O2} \ cdot3H2 {O}.

The preferred percarbonate is percarbonate of sodium of the formula 2Na2CO3 .3H2O2. To increase its stability, percarbonate is preferably used in a form coated.

Organic peracids include all organic peracids traditionally used as bleaches, including, for example, perbenzoic acid and acids peroxycarboxylic acids such as mono- or diperoxyphthalic acid, acid 2-octyldiperoxysuccinic acid diperoxidedecandicarboxylic acid, diperoxyazelaic acid and acid Imidoperoxycarboxylic acid and, optionally, its salts.

The dishwashing detergent according to the invention may also comprise one or more activators of the Whitening. Preferably, these are used in cycle detergents. of dishwasher at temperatures in the range below 60 ° C to in order to achieve an adequate bleaching action. The examples particularly suitable are compounds N- and O-acyl, such as acylated amines, glycolurils acylated or acylated sugar compounds. Preference is given to N, N, N ', N'-tetraacetylethylenediamine (TAED), pentaacetylglucose (PAG) and tetraacetylglycoluril (TAGU). Others suitable bleach activators are, however, complexes of catalytically active metals and, preferably, complexes of transition metals The most preferable is TAED.

Other suitable bleach activators are described in WO 95/01416, whose contents are made Here express reference.

Using MGDA at a relatively low pH, it is It is possible, however, to reduce the use of bleach, and dishwashing detergents according to the invention comprise preferably an oxygen bleach in an amount less than 1% by weight, based on active oxygen. The amount of activator of the bleach used is adjusted accordingly.

In one embodiment, detergents for Dishwashers have a high content of MGDA, such as 25% or more, preferably 30% or more, in each case based on the free acid, and an oxygenated bleaching agent is waived.

The dishwashing detergent according to the invention may also comprise a corrosion inhibitor of silver / copper This expression includes agents that are intended to prevent or reduce the tarnish of non-ferrous metals, in particular silver and copper. Corrosion inhibitors Preferred silver / copper are benzotriazole or bis-benzotriazoles and their substituted derivatives.

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

The benzotriazole derivatives are those compounds in which the available replacement sites on The aromatic ring are partially or completely substituted. The suitable substituents are alkyl groups C 1-20 straight or branched chain e hydroxyl, thio, phenyl or halogen such as fluorine, chlorine, bromine and iodine. A preferred substituted benzotriazole is tolyltriazole.

The appropriate bis-benzotriazoles are those in which benzotriazole groups are each linked in position 6 by a group X, in which X can be a bond, a linear chain alkylene group that is optionally substituted with one or more C 1-4 alkyl groups and preferably it has 1-6 carbon atoms, a cycloalkyl radical having at least 5 carbon atoms, a carbonyl group, a sulfuryl group, an oxygen atom or an atom Sulfur The aromatic rings of bis-benzotriazoles may be substituted as You have previously defined for benzotriazole.

Appropriate organic redox active substances they are, for example, ascorbic acid, indole, methionine, a N-mono- (alkyl C 1 -C 4) glycine, a N, N-di- (alkyl C 1 -C 4) glycine, 2-phenylglycine or a coupling compound and / or developer chosen from the group consisting of diaminopyridines, aminohydroxypyridines, dihydroxypyridines, hydrazones heterocyclics, aminohydroxypyrimidines, dihydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, diaminodihydroxypyrimidines, dihydronaphthalenes, naphthols, pyrazolones, hydroxyquinolines, aminoquinolines, amines primary aromatics that, in the ortho, meta or para position, have another hydroxyl or amino group that is free or substituted with groups C 1 -C 4 alkyl or hydroxyalkyl C 2 -C 4, and di- or trihydroxybenzenes.

Inorganic redox active substances suitable are, for example, metal salts and / or metal complexes chosen from the group consisting of salts and / or manganese complexes, titanium, zirconium, hafnium, vanadium, cobalt and cerium, being the metals in one of the oxidation states II, III, IV, V or VI.

Metal salts and / or metal complexes particularly suitable are chosen from the group consisting of MnSO4, Mn (II) citrate, Mn (II) stearate, Mn (II) acetylacetonate, [1-hydroxyethane-1,1-diphosphonate] of Mn (II), 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 and Ce (NO 3) 3.

Organic redox active substances and inorganic that are suitable as corrosion inhibitors of Silver / copper are also mentioned in WO 94/26860 and WO 94/26859, to whose contents reference is made here.

Suitable paraffin oils are predominantly branched aliphatic hydrocarbons having a number of carbon atoms in the range of 20 to 50. It is given preference to paraffin oil chosen from species C_ {25-45} predominantly branched chain that have a ratio of cyclic to non-cyclic hydrocarbons of 1:10 to 2: 1, preferably 1: 5 to 1: 1.

If a corrosion inhibitor is present silver / copper in the dishwashing detergent according to the invention, preferably it is present in an amount of 0.01 to 5% by weight, particularly preferably in an amount of 0.1 to 2% in weight, of the total weight.

In the embodiment of the invention, in which the MGDA content in dishwashing detergent is sufficiently high, such as 25% or more, preferably 30% or more, based on the free acid in each case, with the result that the bleaching agent can be omitted, it is also possible to resign to a silver / copper corrosion inhibitor.

Other custom additives are, for example, dyes and perfumes and, optionally, in the case of products liquids, preservatives, whose suitable examples are Isothiazolinone-based compounds.

Dishwashing detergents according to invention are not caustic and therefore do not require packaging particularly safe A good detergency can be achieved using a relatively low amount of use of 15-20 g of powder or 20-50 ml of liquid detergent. According to him current knowledge, none of the ingredients is toxic or harmful to health in any other way. Detergents described here also represent an alternative Ecological and user friendly to conventional detergents that contain complexing agents that are effective in the range strongly basic.

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

2

Methylglycindiacetic acid is used particularly preferable as the free acid, or as the sodium salt or potassium, and is preferably present in the detergent dishwasher in an amount of 3% to 90%, based on acid free.

In bleach-free detergents for dishwasher, which are based on phosphates as the main constituents of the reinforcing system, the amount of MGDA is preferably at least 5%, based on the free acid.

According to the invention, it is essential that a aqueous solution of concentration approximately 0.5% of detergent has a pH not exceeding 10.4. The pH of a solution aqueous concentration approximately 0.5% of the detergent according to the invention is preferably from more than 6 to 10.4, so particularly preferable from 7 to 10.0.

The following comparative experiment demonstrates that the dishwashing detergents proposed in the article of the SÖFW Journal 122, 1996, 392-397, have, in aqueous solutions of 0.5% concentration, a pH greater than 10.4. The description of this article therefore agrees with the theoretically expected that MGDA is an excellent agent complexing at a pH higher than 10.4, but is lower than the NTA traditional at a pH of 10.4 or less.

Experiment comparative

According to the description of the article in the SÖFW Journal 122, 1996, 392-397, are prepared dishwashing detergents from the following constituents:

Sodium Citrate Dihydrate

Sodium carbonate

Sodium hydrogen carbonate

Sodium perborate monohydrate

TAED

C13 {C} {4} Oxoalcohol + 4 moles of PO + 2 moles of EO

MGDA (trisodium acid salt methylglycostatic acid) (77% concentration solution in water) = TRILON ES 9964 obtained from BASF AG.

The following table shows the amounts of respective constituents in grams and percentage. The constituents dissolved in a liter of water that has a hardness of 10 °, and the pH of the solution was determined in each case. The total amount of the constituents (100%) is in each case 4 g, corresponding to a concentration of 0.4%, as described in the Figure 14 of the article.

MGDA in pure form is not commercially available and therefore a concentration solution was used 77% in water. Therefore, a greater amount of the commercially available product, as the table shows. For him MGDA, the table gives two values in each case. The first value is the quantity in g of the commercial product, and the second value corresponds to the corresponding amount of pure substance (100%).

3

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4

Although the pH of the 0.5% concentration solutions of the agents, the pH of solutions of concentration 0.4%. At a concentration higher of the detergent, the detergent solutions will have obviously the same or, more likely, a higher pH.

The following example shows that when replaces part of the booster of a dishwasher detergent by methylglycindiacetic acid, at a low pH, it can be achieved excellent detergency and, in particular, contrary to what is theoretically expected, the ability to eliminate milk residues and Tea waste is higher than in the case of other complexing agents traditional such as NTA. The example illustrates the invention.

Example

Liquid dishwashing detergents were prepared which have a composition as given in Table 1 (both according to invention using MGDA as using the usual NTA in the art above), and its detergency was determined using soiled dishes with residues of both milk and tea. In this experiment, you essentially followed DIN Standard No. 44990, part 2. It used a Bosch SMS 5062 dishwasher. The water had a hardness of 19º of German hardness (3.39 mmol of calcium carbonate), the water temperature was 65 ° C and 20 ml of detergent was used in each case. The results of the detergency were evaluated in a 1 to 5 scale (in which 5 represents 100% clean dishes), and They are also given in Table 1.

The nonionic surfactant is an alcohol usual ethoxylated and propoxylated fatty, which forms little foam. Be They used usual proteases and amylases.

TABLE 1

5

The results in Table 1 show that, in a pH range below 10.4, detergents comprising MGDA achieve surprisingly better results both in the milk waste disposal as in waste disposal of tea than the corresponding detergents comprising the NTA usual instead of MGDA.

Claims (3)

1. A dishwashing detergent comprising sodium or potassium salt of methylglycindiacetic acid as a complexing agent, which is characterized in that, in an aqueous solution of approximately 0.5% concentration, it does not exceed a pH of 10.4, containing the detergent for dishwasher an oxygenating bleaching agent in an amount less than 1% based on the weight of active oxygen. 2. The dishwashing detergent according to claim 1, characterized in that, in an aqueous solution of approximately 0.5% concentration, it has a pH of 6 to 10.4. 3. The use of methylglycindiacetic acid, or its salts, as a total or partial substitute for reinforcing agents or complexing agents in dishwashing detergents with a pH not greater than 10.4 in aqueous solution of concentration approximately 0.5%, to improve your ability to eliminate milk waste and also tea waste.