EP2039750A1 - Mixture for removing limescale, cleaning and/or disinfecting - Google Patents

Abstract

Mixture for decalcifying, cleaning and/or disinfecting, comprises at least 25 wt.% of citric acid and 0.1-75 wt.% of an additive mixture comprising malic acid and/or tartaric acid. An independent claim is included for a liquid composition comprising a mixture and at least a solvent.

Description

The present invention relates to a mixture for descaling, cleaning and / or disinfecting and their use.

Generic mixtures are known in large numbers from the prior art. One of the most well-known descaling agents is the use of pure citric acid. However, in particular their descaling performance is not as high as desired, that is, in particular with strong calcifications correspondingly calcified surfaces must be treated several times with a solution of citric acid. A citric acid-containing cleaning agent, which is particularly suitable for cleaning calcified, vertical surfaces, is in the DE 43 11 713 C1 disclosed. The detergent disclosed therein comprises 10-35% citric or tartaric acid as well as glycerol, ethylene glycol, propylene glycol or polyethylene glycol 300-400.

Furthermore, for example, from the DE 23 59 095 C2 a cleaning and descaling agent and a process for its preparation, this being particularly suitable for the cleaning of sinks or the like. The cleaning and descaling agent disclosed therein comprises at least one mineral acid and from 0.5 to 50% by weight of an alkoxylated amine in aqueous solution, wherein additionally an organic acid, an organic acid anhydride or a salt of an organic acid may be added to give a thickening effect of an ethoxylated or propoxylated tertiary amine. As the organic acid, for example, citric acid or tartaric acid can be used.

In addition, decalcifiers based on citric acid are known on the market, which have amidosulfonic acid as a further additive. This is intended to speed up the descaling process.

Despite the various descaling, cleaning and / or disinfecting agents known from the prior art, there remains a need for simply composed means which are cost-effective, easy to use and easy to process, in particular not or not very irritating.

It is therefore an object of the present invention to provide a corresponding mixture in powder form and a corresponding liquid composition available.

This object is achieved by a mixture for descaling, cleaning and / or disinfecting, comprising at least about 25 wt .-%, based on the total amount of the mixture, citric acid, and about 0.1 to 75 wt .-%, based on the Total amount of the mixture, an additive mixture comprising malic acid and / or tartaric acid. As far as in the present invention of weight percent is mentioned, these always refer to the total amount of the mixture according to the invention. Of course, the ingredients of the additive mixture are not included again in the mixture.

Surprisingly, the mixture according to the invention has a synergistic effect in comparison with the use of pure citric acid on the one hand and malic acid or tartaric acid on the other hand with regard to the particular descaling performance. Thus, with the mixture according to the invention, descaling performances are already achieved after a single cleaning, which goes beyond the descaling performance of pure citric acid on the other hand, but also known rapid scorers, in addition to citric acid, amidosulfonic acid. The mixture according to the invention shows a very quick lime dissolution of limescale on surfaces, for example in coffee machines, Wasserkochem, water heaters, but also other surfaces, especially in sanitary facilities, in the kitchen area or in washing machines.

The additional mixture of the mixture according to the invention preferably comprises both malic acid and tartaric acid, the weight ratio of malic acid to tartaric acid preferably being in a range from about 1: 6 to 6: 1, more preferably in a range from about 0.8: 1 to 4: 1, even more preferably in a range from about 1: 1 to about 3.8: 1. The additional mixture may in principle comprise malic acid, tartaric acid, but also other carboxylic acids such as lactic acid or maleic acid. However, the inventors have found that when using malic acid and tartaric acid not expected improvements in the descaling performance of the mixture according to the invention are detectable. Particularly preferred are additional mixtures which contain malic acid in excess, based on the amount by weight, in comparison with tartaric acid.

The mixture according to the invention furthermore comprises in particular a buffering agent. The buffering agent may be selected from buffering agents known in the art, and includes, in particular, inorganic and organic buffering agents. For example, sodium hydroxide and potassium hydroxide can be used as buffering agents. but especially also phosphorus-containing compounds, mono- and polyvalent salts such as silicates, carbonates and borates, certain acids and bases, citrates, tartrates and certain acetates. The aforementioned list is not intended to be limiting. Buffering agents are each known in the art to those skilled in the art, and they are suitable for the particular application, and especially with respect to the organic acids such as citric, malic and tartaric acids and other possible additives with regard to compatibility will choose with these. Salts of organic acids having 1 to 6 carbon atoms, in particular trisodium citrate, are particularly preferred as buffering agents. The buffering agent may preferably be present in the blend according to the invention in an amount of about 0.5-10% by weight, more preferably about 1.0 to about 5% by weight, even more preferably about 1.5 to about 4% by weight. % be used.

However, the addition of other further additives in the mixture according to the invention, which are known to the person skilled in the art, can also be included in the mixture according to the invention. Examples include, but are not limited to, surfactants, perfumes and perfumes, perfume carriers, optical brighteners, but also colorants such as dispersible pigments and dyes. Specifically excluded from the aforementioned additives are solvents, both aqueous and anhydrous, such as alcohols, glycols and glycol ethers. These may be part of a liquid composition according to the invention comprising the mixture according to the invention. The above-mentioned additives will also be selected by the person skilled in the art against the background of the other constituents of the mixture used with regard to complete compatibility with them and added in appropriate amounts if desired.

Preferably, the mixture according to the invention comprises at least about 75% by weight, preferably with about 80% by weight of citric acid and at least about 3% by weight of the additional mixture. In a further preferred embodiment of the mixture according to the invention, the additional mixture comprises about 1 to about 30% by weight of malic acid and about 0.5 to about 10% by weight of tartaric acid, preferably about 2 to 10% by weight of malic acid and about 0.5 5% by weight of tartaric acid, more preferably about 5% to 9% by weight of malic acid and about 1% to 3% by weight of tartaric acid, the percentages by weight in each case being based on the entire mixture. If the mixture according to the invention is to be used in washing machines, the additional mixture preferably comprises about 5% by weight to about 22% by weight, more preferably from about 10 to about 20% by weight of malic acid, and about 2% by weight to about 7% by weight Tartaric acid, in each case based on the total amount of the mixture. In addition, in particular, buffering agents may be included in this.

In a further preferred embodiment, in particular for use outside of washing machines, for example in the decalcification of coffee machines and water chemicals, the mixture according to the invention comprises about 89 to about 96% by weight of citric acid and about 4 to about 11% by weight of the additional mixture, consisting of about 3 to about 9% by weight of malic acid and about 1 to about 7% by weight of tartaric acid. More preferably, the above-defined mixture according to the invention comprises 0.5-5% by weight of buffering agent, more preferably about 2% by weight to about 4% by weight of buffering agent, preferably trisodium citrate.

Advantageously, the mixture according to the invention is water-soluble, but also other non-aqueous solvents such as alcohols, glycols, etc., or mixtures of these can be used, in particular if it is desired to use the mixture according to the invention for cleaning oblique or vertical surfaces. Optionally, then as additives corresponding solubilizers may still be added. The preparation of a water-soluble mixture can be carried out simply by mixing in accordance with predetermined amounts of the mixture according to the invention with water, preferably deionized water, in particular with stirring.

Advantageously, the concentration of a solution of the mixture according to the invention is in a range of about 10 g / l to about 150 g / l, wherein the aforementioned numerical values mean that, for example, 10 g of the mixture according to the invention are dissolved in one liter of solvent, in particular water. Surprisingly, the inventors have found that certain concentration ranges of the mixture according to the invention in aqueous solution are particularly advantageous. Thus, at certain concentrations of the mixture according to the invention and in particular for certain compositions of the additional mixture, areas can be found which show a maximum leaching capacity. If, for example, an additional mixture used is one in which the weight ratio of malic acid to tartaric acid is 1: 3, and if a concentration of the mixture according to the invention of 50 g / l of water is selected, the range is about 9% by weight of the additional mixture , But also in a range between 11 - 40 wt .-% of the additional mixture to determine a high Kallösösevermögen. If the concentration of the mixture according to the invention is increased to 100 g / l, the mixture according to the invention exhibits a particularly good laking capacity when the additional mixture is added in the ranges of about 6 wt% to 15 wt% and about 20 wt% to about 30 wt%.

If a weight ratio of malic acid to tartaric acid of 1: 1 is selected, a particularly high level of leaching power can be found in a concentration of 20 g / l of the mixture according to the invention in water in a range from about 30% by weight to 70% by weight additional mixture On the other hand, at a concentration of 50 g / l of the mixture in water, a particularly high level of lime-dissolving power is possible when the additional mixture is added in a range from about 10% by weight to 30% by weight, with a pronounced maximum between 18% by weight and about 22% by weight. If the concentration is further increased to 100 g of said mixture per liter of water, so on the one hand in a range of about 6 wt .-% to 14 wt .-% and on the other hand in a range of about 25 wt .-% to about 45 wt .-% addition of the additional mixture a particularly high lime dissolving power can be found.

If, on the other hand, the additional mixture is chosen such that the additional mixture has a weight ratio of malic acid to tartaric acid of about 3: 1, then at a concentration of 50 g of the mixture per liter of water a particularly high level of lime-dissolving capacity in ranges of about 4% by weight to about 10 wt .-% or about 20 wt .-% to about 35 wt .-% of the additional mixture obtained, with a further increase in the concentration of the mixture according to the invention to 100 g per liter of water, the range of very good Kalklösöses with the addition of about 4 Wt .-% to about 20 wt .-% and about 45 wt .-% to about 75 wt .-% additional mixture is detectable.

The abovementioned preferred ranges relating to the composition of the mixture according to the invention show that with regard to the provision of a mixture which is as economical as possible, in particular pulverulent, the additive mixture is present in an amount in a range from about 3% by weight to about 25% by weight in the The mixture should preferably contain the weight ratio between malic and tartaric acid in a range from about 0.8: 1 to about 4: 1.

The present invention relates not only to a particular pulverulent mixture but also to a liquid composition comprising the mixture according to the invention and at least one solvent. Preferably, the solvent is water, but it can also be anhydrous solvents or aqueous solutions, which in addition to water have other solvents used. The concentration of the mixture according to the invention is selected in a range from about 10 g to about 150 g per liter of solvent or solvent mixture. By providing a liquid composition, the users can readily be offered a ready-to-use product, which can be used in particular for cleaning surfaces, etc., for example also in spray bottles or the like. If, however, for example, the descaling of a kettle or a washing machine desired, preferably the powdered mixture according to the invention will be used, which is simply entered into the kettle or the filling shaft of the washing machine and subsequently filled the container with water or the washing machine in a conventional washing program, preferably in a program with temperatures of more than 30 ° C, filled or operated to achieve a decalcification. Optionally, the decalcification processes are repeatable even with very stubborn and fixed lime.

The liquid composition according to the invention preferably has a pH in the range from about 1 to about 4, more preferably in a range from about 1.5 to about 3.5, before use. After performing descaling, the pH may be somewhat below the above values, but will preferably be at least 1.5.

Finally, the present invention relates to the use of a powdery mixture according to the invention and a liquid composition according to the invention for the decalcification, cleaning and / or disinfecting of surfaces. Surfaces within the meaning of the present invention are to be understood very broadly, and also include surfaces of appliances or appliance parts, such as, for example, coffee makers, water kosher, washing machines or the like. The mixture and composition according to the invention is suitable both for cleaning soft and hard surfaces. Hard surfaces which can also be cleaned by the mixture and composition according to the invention are those which can be found in sanitary ware or kitchen equipment, such as work surfaces, tiles, tiles, porcelain stoneware or the like, but also surfaces of shower cubicles, bath and shower trays, sinks, Bidets, toilets and other bathroom accessories such as shelves, curtains, shower doors, shower rods, etc. But also calcifications within vases or other vessels can be removed with the mixture and liquid composition of the invention.

Fig. 1

Vergleich der Entkalkungsleistung verschiedener handelsüblicher und erfindungsgemäßer Zusammensetzungen;

Fig. 2

Vergleich des Kalkslösevermögens bei unterschiedlichen Konzentration und Gewichtsverhältnissen in der eingesetzten Zusatzmischung;

Fig. 3

Vergleichsbeispiel betreffend die Entkalkung einer Kaffeemaschine mit reiner Zitronensäure in einer Konzentration von 15 g in 300 ml Lei- tungswasser;

Fig. 4

Beispiel der Entkalkungsleistung einer erfindungsgemäßen Mischung in einer Konzentration von 15 g in 300 ml Leitungswasser anhand der Ent- kalkung einer Kaffeemaschine;

Fig. 5

Vergleichsbeispiel betreffend die Entkalkung einer Kaffeemaschine mit reiner Zitronensäure in einer Konzentration von 15g in 500 ml Lei- tungswasser;

Fig. 6

Beispiel der Entkalkungsleistung einer erfindungsgemäßen Mischung in einer Konzentration von 15 g in 500 ml Leitungswasser anhand der Ent- kalkung einer Kaffeemaschine.

These and other advantages of the present invention will become more apparent from the following examples and drawings. The figures show in detail:

Fig. 1

Comparison of the descaling performance of various commercial and inventive compositions;

Fig. 2

Comparison of the lime-dissolving power at different concentrations and weight ratios in the additional mixture used;

Fig. 3

Comparative example relating to the decalcification of a coffee machine with pure citric acid in a concentration of 15 g in 300 ml of tap water;

Fig. 4

Example of the descaling performance of a mixture according to the invention in a concentration of 15 g in 300 ml of tap water on the basis of the descaling of a coffee machine;

Fig. 5

Comparative example relating to the decalcification of a coffee machine with pure citric acid in a concentration of 15 g in 500 ml of tap water;

Fig. 6

Example of the descaling performance of a mixture according to the invention in a concentration of 15 g in 500 ml of tap water on the basis of the descaling of a coffee machine.

First, it should be noted that the invention is not limited to the blends and liquid compositions shown in the figures. Rather, the features respectively disclosed in the description including the description of the figures and the further examples can be combined with those mixtures and compositions according to the invention, as they are based on the figures, with regard to their characteristics.

• Carrara-Marmorplatten mit einer Größe von 10 x 20 cm (Lieferant: Michael Kleibrink, Gartenweg 10, 34439 Peckelsheim) wurden ausgewogen und nachfolgend auf eine in einem 2 I-Becherglas befindliche Lochplatte gestellt. Anschließend wurden wässrige Zusammensetzungen bestimmter Konzentrationen in das Becherglas gegeben, die im Becherglas befindliche Lösung auf etwa 90 °C erhitzt und mit 750 U/min mittels eines üblichen Magnetrührers gerührt. Nach 30 min wurde die Marmorplatte aus der Lösung genommen, unter kaltem Wasser abgespült und für eine Stunde bei 120 °C in einem Trockenschrank bis zur Gewichtskonstanz getrocknet. Nachfolgend wurde deren Gewicht bestimmt, so dass aus der Gewichtsdifferenz eine prozentuale Gewichtsabnahme ermittelt werden kann. Je höher die dabei ermittelte Prozentzahl, um so besser das Kalklösevermögen. Es wurde stets mindestens eine Doppelbestimmung vorgenommen.

In the following, the methods for the determination of the lime removal rate as well as the decalcification rate in the practical application are described in more detail:

• Carrara marble slabs with a size of 10 x 20 cm (Supplier: Michael Kleibrink, Gartenweg 10, 34439 Peckelsheim) were balanced and subsequently to a in a 2 I-beaker located perforated plate placed. Subsequently, aqueous compositions of certain concentrations were added to the beaker, the solution in the beaker heated to about 90 ° C and stirred at 750 U / min by means of a conventional magnetic stirrer. After 30 minutes, the marble plate was removed from the solution, rinsed under cold water and dried for one hour at 120 ° C in a drying oven to constant weight. Subsequently, their weight was determined, so that from the weight difference, a percentage weight loss can be determined. The higher the percentage determined, the better the laking properties. At least one duplicate determination has always been made.

To determine the descaling performance under practical conditions, commercial coffee machines (Krups, ProAroma F309 7C10, Braun, AroMaster KF47 type 4069), which were free of limescale, were calcified with 147 liters of tap water having a hardness of about 16 ° dH. Subsequently, the liquid decalcification compositions to be tested were added to the calcified coffee machines in an amount of 300 ml or 500 ml, and the run-through aqueous solution now containing dissolved lime was collected in 50 ml portions. From these 50 ml portions of the calcium content, magnesium content and the pH was then determined by conventional methods. Each experiment was repeated three or four times and the corresponding results were averaged. The aqueous decalcifier composition to be tested was allowed to pass through a calcified coffee machine up to eight times in an amount of 300 ml or 500 ml.

Investigated mixtures or liquid compositions:

For comparison, solutions of 15 g of pure citric acid (obtained from Kraemer & Martin GmbH, Sankt Augustin, Germany), designated HCitr in the figures, in an amount of 15 g in 500 ml and 300 ml tap water, respectively, of about 16 ° dH (became used throughout). Furthermore, a so-called "rapid decalcifier" was examined as a comparison, which is composed of 88 wt .-% citric acid, 6% trisodium citrate and 6 wt .-% sulfamic acid (manufacturer is applicant), and in an amount of 15 g in 500 ml or 300 ml of tap water was dissolved. In addition, three mixtures according to the invention were prepared. The first mixture according to the invention comprised 92% by weight of citric acid, 6% by weight of malic acid and 2% by weight of tartaric acid (malic acid and tartaric acid purchased via Rewe Food Ingredients Handelsgesellschaft mbH, Cologne, Germany). Furthermore, a second mixture was prepared containing 89% by weight of citric acid, 6% by weight of malic acid, 2 % By weight of tartaric acid and 3% by weight of trisodium citrate as a buffering agent. These mixtures according to the invention are described in the Fig. 1 labeled "Express Descaler". As abbreviations for malic acid in the figures the name HMalic, for tartaric acid the name HTartr, and for the buffering agent trisodium citrate the name NaCitr chosen. The buffer mixture contained mixture was dissolved in an amount of 15 g in 500 ml of tap water, whereas the buffer-free mixture on the one hand an amount of 15 g was dissolved in 300 ml of tap water, on the other hand in 500 ml of tap water. For the aforementioned mixtures are in Fig. 1 compared the descaling after a first run based on the complete descaling by a coffee machine calcified as described above in percent comparison. In the Fig. 3 to 6 on the other hand, the descaling performance in the decalcification of coffee machines for a comparative solution with 15 g of dissolved citric acid in 300 ml ( Fig. 3 ) or 500 ml ( Fig. 5 ) Tap water to a mixture according to the invention with 92 wt .-% citric acid, 6 wt .-% malic acid and 2 wt .-% tartaric acid, also dissolved in an amount of 15 g in 300 ml ( Fig. 4 ) or 500 ml ( Fig. 6 ) Tap water, faced.

In addition, a series of experiments for determining the lime release capacity of marble slabs was carried out such that starting from pure citric acid additions to the additional mixture containing malic acid and tartaric acid in certain weight ratios, in an amount ascending to 100 wt .-%, was determined. As a result, a comparison of the Kallösösevermögens different mixtures directly with pure citric acid on the one hand and on the other hand additional mixtures with malic acid and tartaric acid can be determined. The weight ratio of malic acid to tartaric acid was chosen in the range of 1: 3, 1: 1 and 3: 1. The corresponding results are Fig. 2 refer to.

As first Fig. 1 it can be seen, the descaling, measured at coffee machines in practical operation as described above, after a first pass for the inventive express descaling mixture or the corresponding liquid composition, in a concentration of 15 g of the mixture in 500 ml of tap water by far highest, wherein also a buffered express descaler mixture or liquid composition has a better descaling performance than the known from the prior art and comparatively listed quick lime, but also in comparison to pure citric acid having. It is noteworthy that an increase in the concentration of the express descaling agent does not lead to an increase in the descaling performance, as is the case with one concentration of 15 g of the decalcifying mixture and 300 ml of tap water is evident. In particular, if one considers the descaling performance between the express descaling agent according to the invention and pure citric acid in a concentration of 15 g each in 500 ml tap water, an approximately 50% higher descaling performance can be determined. If, however, the concentration is changed to 15 g dissolved in 300 ml of tap water, the express descaling agent according to the invention still has a higher descaling performance, but here the identifiable differences are not so great.

Fig. 3 now shows the descaling performance by the multiple cleaning of a calcified coffee machine with a solution of 15 g of citric acid in 300 ml of tap water, Fig. 5 with a solution of 15 g of citric acid in 500 ml of tap water. The contents of the determined calcium and the determined magnesium are plotted on the left and right Y-axis. Fig. 4 and Fig. 6 show a corresponding diagram relating to the descaling performance of a mixture according to the invention or aqueous composition of the express descaling agent in a concentration of 15 g in 300 ml and 500 ml of tap water. From the comparison of Fig. 3 and 4 respectively Fig. 5 and Fig. 6 It can be seen that with each pass of the descaler solution, starting from the first decalcifying to the eighth decalcification, the inventive express decalcifier a better decalcifying performance. In this case, after a fifth round of 300 ml or 500 ml express descaler through the coffee maker to be descaled the descaling process is substantially complete, whereas in the comparative example, in particular the magnesium content by subsequent descaling until the eighth descaling further increased.

Fig. 2 Finally, there is an overview of the dependence of the lime dissolving power of citric acid-containing mixtures, to which an additional mixture of malic acid and tartaric acid in different proportions by weight has been added. At a concentration of 50 g of the respective mixture or pure citric acid, based on 500 ml of tap water, is how Fig. 2 It can be seen to find a higher lime dissolving power, determined on marble plates according to the method described above, compared to solutions of 25 g in 500 ml of tap water or only 10 g in 500 ml of tap water. At concentrations of the aqueous solutions of 50 g in 500 ml of water, pronounced maxima appear. Thus, with a weight ratio of malic acid to tartaric acid of 1: 3 at a concentration of 50 g in 500 ml of water, a maximum calendering power in a range from about 8 to about 12% by weight of additive mixture is observed, and another maximum in a range of from about 28% to about 32% by weight. If, however, the weight fraction of Malic acid to tartaric acid is changed to 1: 1, with otherwise constant conditions being a weak peak in a range of about 8 to about 12 wt .-% of the additional mixture and a broad maximum in a range of about 25 wt .-% to determine about 45 wt .-%. If, on the other hand, a weight proportion of malic acid to tartaric acid of 3: 1 is selected under otherwise constant conditions, then a first small maximum in a range from about 6 to about 10% by weight of the additional mixture, which also in the proportions by weight of malic acid to tartaric acid from 1: 3 and 1: 1 was in evidence, and incidentally, a very wide maximum in a range of about 45 wt .-% to about 75 wt .-% of the additional mixture determine.

When a concentration of 25 g in 500 ml of tap water is selected, a pronounced maximum in a range from about 6% by weight to about 9% by weight, another broader maximum, is evident when the weight of malic acid to tartaric acid is 3: 1 in a range of from about 25 to about 35 weight percent, and another broad maximum with a weight percent range of from about 45 to about 70 weight percent of the additive mixture. At a weight proportion of malic acid to tartaric acid of 1: 1 under otherwise identical conditions almost no more maximum is detectable, and at a weight proportion of malic acid to tartaric acid of 1: 3 is a first secondary maximum in a range of about 13 to about 17 wt .-% and a main maximum in a weight percent range of about 22 to about 30 weight percent can be seen.

Fig. 2 clearly shows that certain weight percent ranges of the additional mixture have a decisive influence on the laking properties of the mixture or liquid composition according to the invention, and that in addition to the principle that increasing the concentration always leads to higher leaching properties, also the weight proportion of malic acid to tartaric acid of decisive influence is.

In general, the investigated concentrations of 25 g and 50 g, each dissolved in 500 ml tap water, that in the range between about 6 and about 11 wt .-%, a maximum or secondary maximum is detected. Even with these small additional amounts of additional mixture is a significant improvement in the calcifying power compared to pure citric acid found. Especially with regard to the costs of a decalcifying or disinfecting and cleaning agent that can be economically produced and sold, mixtures of citric acid with an addition of an additional mixture are therefore generally in a range from about 3% by weight to about 25% Wt .-% at quite varying proportions by weight of malic acid to tartaric optimal. In addition, especially with regard to the compatibility / irritation of a corresponding mixture or liquid composition of such a mixture, appropriate buffering agents, but also other additives may be added. Liquid compositions according to the present invention may in particular also be in the form of concentrates, in which case the user dilution with ideally deionized water, but also ordinary tap water to the desired concentrations, in particular concentration ranges from about 20 g to about 100 g in one liter of water , more preferably about 22 g to about 50 g in one liter of water, make.

As a result of the mixture according to the invention, a more effective, more cost-effective and also easy-to-handle agent is thus made available with regard to the lime-removal capability. Moreover, since corresponding solutions also have a bactericidal or viricidal activity, the corresponding mixtures and liquid compositions are at the same time also suitable for cleaning and / or disinfecting surfaces of any type.

Claims (14)

Descaling, cleaning and / or disinfecting mixture comprising at least 25% by weight, based on the total amount of the mixture, of citric acid and 0.1-75% by weight, based on the total amount of the mixture, of an admixture comprising malic acid and / or tartaric acid. Mixture according to claim 1, characterized in that the additional mixture comprises malic acid and tartaric acid. Mixture according to one of the preceding claims, characterized in that the weight ratio of malic acid to tartaric acid in a range of about 1: 6 to about 6: 1. Mixture according to one of the preceding claims, characterized in that it further comprises at least one buffering agent. Mixture according to one of the preceding claims, characterized in that the mixture comprises at least 75% by weight of citric acid and at least 3% by weight of the additional mixture. Mixture according to one of the preceding claims, characterized in that the additional mixture comprises 1 to 30% by weight of malic acid and 0.5 to 10% by weight of tartaric acid. Mixture according to one of the preceding claims, characterized in that it is water-soluble. Mixture according to one of the preceding claims, characterized in that the concentration of this solution is in a range of about 10 g / l to about 150 g / l. Mixture according to one of the preceding claims, comprising 89-96% by weight of citric acid and 4-11% by weight of the additional mixture consisting of 3-9% by weight of malic acid and 1-7% by weight of tartaric acid. Mixture according to one of claims 1 to 8, comprising 12 to 27 wt .-% of the additional mixture comprising 10 to 20 wt .-% malic acid and 2 to 7 wt .-% tartaric acid. Mixture according to one of the preceding claims, characterized in that it comprises 0.5-5% by weight of buffering agent. A liquid composition comprising a mixture according to any one of claims 1 to 11 and at least one solvent. Liquid composition according to claim 12, characterized in that water is selected as the solvent. Use of a mixture according to any one of claims 1 to 11 or a liquid composition according to any one of claims 12 to 13 for decalcifying, cleaning and / or disinfecting surfaces of any kind.

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