EP2529656B1 - Dishwasher detergent, use of the dishwasher detergent in a dishwasher, dishwasher and method for operating said dishwasher - Google Patents

Description

The invention relates to a method for operating a dishwasher in the embodiment as a household dishwasher and / or industrial dishwasher, but not as a conveyor dishwasher.

In the field of detergents so-called Spültabs and liquid detergents are known. The liquid rinsing agents are also used for cleaning items in the range of commercial kitchens or catering business. In the field of liquid rinsing agents, i.a. Also one-component detergent used in the high alkaline range.

The EP 1 275 708 A1 discloses a two-component bleach composition. One of the components is a hydrogen peroxide solution which is present in a sulfuric acid solution. The second component is an alkaline solution.

The WO 96/161152 A1 discloses in the comparative examples a detergent with potassium hydroxide and in a variant a hydrogen peroxide agent. However, both of these seem to be already contained in one and the same component. The document distinguishes between different pH ranges.

The EP 1 454 637 A1 discloses a means for cleaning and disinfecting medical instruments.

The WO 2009/034067 A1 discloses a method of cleaning dishes by means of an oxidizer and an alkaline detergent.

The WO92 / 18047 A1 discloses a method for cleaning dishes in which an alkaline detergent is presented. In this case, with a known alkali content of the alkaline cleaning agent required for the desired neutralization dosage of the acidulant to be made possible by a simple comparison of quantities without relatively expensive conductivity measurements. Moreover, the document describes that in the rear zone of the dishwasher, in 3-tank machines in the third tank, the bath of liquor to be sprayed on consists of a substantially aqueous solution containing an acidic agent. This is done by automatically dosing an acidulant to the tank of the dishwasher, the solution of which is last applied to the dishes to be cleaned, and preferably has a pH of from 2 to 6.5, in particular from 2 to 3.

The WO 91/00044 A1 discloses an alkaline detergent and an active oxygen-containing agent, which was added by means of a metering pump and a metering squeeze pump to a rinsing liquor. This is initially a parallel dosing. Subsequently, an emergency emergency dosage of active oxygen is made again and again.

The EP 1 354 549 A2 discloses a dishwasher. This includes a pH measuring station. The WO 03/059143 A1 discloses the construction of a dishwasher.

It is an object of the invention to achieve an improved cleanliness of the items to be washed by a method for operating a dishwasher.

The invention solves this problem by the subject matter of claim 1.

1. A) Zudosieren einer stark-alkalischen Lösung mit einem pH-Wert von größer als pH=12 zu einer Spülflotte ; und
2. B) Zudosieren einer wasserstoffperoxidhaltigen Lösung zu der Spülflotte.

According to the invention, the method for operating a dishwasher includes the following steps:

1. A) adding a strongly alkaline solution having a pH greater than pH = 12 to a rinsing liquor; and
2. B) adding a hydrogen peroxide-containing solution to the rinsing liquor.

The special combination of the strong alkaline solution and the oxidizing agent makes it possible to detach better from many types of soiling on dishes.

An increased oxidizing capacity of the oxidizing agent, and thus an additional increase in the cleaning ability, is advantageously achieved by the metered addition of the oxidizing agent-containing solution, according to step B, only after an amount of strong alkaline solution from step A) has already been added to the rinsing liquor , There are known oxidizing agents, in particular hydrogen peroxide, which lose their oxidation action in basic solution after several minutes, since due to the increased reactivity of a basic or alkaline hydrogen peroxide solution is a faster conversion of the hydrogen peroxide into water and oxygen. This basically speaks for the use of hydrogen peroxide in dishwashers, since the degradation products of hydrogen peroxide completely harmless for use are in the food sector. On the other hand, the increased oxidation effect allows a short-term high cleaning effect immediately after metering in to the alkaline rinsing liquor. This is the higher, provided that the metered addition of the oxidizing agent takes place only after the metered addition of the strongly alkaline solution, so that the alkaline washing liquor can already dissolve a part of the soiling before the short-term oxidation effect of the oxidant-containing solution comes to fruition.

In order to achieve an economical use of the individual components with optimum cleanliness of the items to be washed, for example dishes, the metered addition of the strongly alkaline solution, according to step A, and the metered addition of the oxidant-containing solution, according to step B, by means of a metering.

According to the invention, the metered addition of an oxidant-containing solution to the rinsing liquor starts in a time interval of 40 seconds to two minutes later than the metered addition of the strongly alkaline solution to the rinsing liquor. This time difference is sufficient to solve most soiling.

According to the invention, the concentration of dosed alkaline solution in the rinsing liquor is 1 to 2 g / l. This concentration range is suitable for achieving a good cleaning result and at the same time avoids excessive contamination of the waste water by a too high pH value or by an excessive concentration of hydroxide ions in the wastewater.

The water hardness influences the cleaning effect of the alkaline solution. Therefore, with hard water, a higher concentration of alkaline solution must be added than with soft water. It has proved to be favorable if the concentration of dosed alkaline solution in the rinsing liquor is 1 to 2 g / l with a water hardness of less than or equal to 14 ° dH.

Regardless of the water hardness, a concentration of dosed oxidant-containing solution in the rinse liquor 0.5 to 1 g / l has proven to be the optimum amount to achieve a good cleaning result with economical consumption.

A ratio of oxidant-containing solution to alkaline solution when metered 1: 1 to 1: 8 has been found to be particularly advantageous.

There is provided a multi-component rinse aid for machine wash ware cleaning such as dishes, cookware, kitchen utensils, and cutlery, comprising at least a first component having a strong alkaline solution having a pH greater than pH = 12, and having a second component with a hydrogen peroxide-containing solution.

In order to achieve a high reactivity of the hydrogen peroxide after metering, if the strongly alkaline solution according to the invention has a pH of greater than pH = 12 and thereby also a correspondingly high basicity of the wash liquor is provided before the metering of the oxidizing agent.

The use of both components in the machine cleaning or during the automated cleaning of items to be washed, leads to an improved cleaning result over conventional cleaners based on strong alkaline detergent.

The components are preferably stored spatially separated from each other and can be purchased separately packaged.

It is advantageous if the hydrogen peroxide-containing solution has a hydrogen peroxide content of more than 10% by weight, preferably more than 25% by weight. As a result, an intensive action of the oxidizing agent on the corresponding pollution is achieved. Even in such high concentrations, the use of hydrogen peroxide is harmless, since the interaction with the strong alkaline solution and the elevated temperature of the wash liquor, a rapid and complete degradation of excess hydrogen is achieved.

The metered-in strongly alkaline solution and the oxidant-containing solution combine to produce a high quality of cleaning within a very short period of time after metering. In principle, therefore, any domestic dishwasher can be used as a dishwasher. However, the use of the detergent in an industrial dishwasher has proven to be particularly advantageous.

A dishwasher has a dosing, for dosing a strong alkaline solution having a pH greater than pH = 12 to a rinsing; and for metering an oxidant-containing solution to the rinsing liquor.

By dosing an optimal ratio of the strong alkaline solution and the oxidant-containing solution can be adjusted, whereby an adjustment of the overall reactivity can be done. As a result, a better cleaning result can be achieved.

Further, it is advantageous if the dosing has a control for the time-delayed metered addition of the strong-alkaline solution and the oxidant-containing solution. This makes it possible to optimize the longer exposure time of the alkaline solution with the oxidation effect of the oxidant-containing solution.

It is also advantageous if the dosing has a first pump for dosing a strong alkaline solution having a pH greater than pH = 12 to a rinsing liquor and a second pump for dosing a solution containing oxidizing agent to the rinsing liquor. As a result, the functionality can be maintained, even in the unlikely event of a pump failure, at least insofar as the respective second component is supplied. This does not lead to a complete standstill of the entire dishwasher, but only to a less satisfactory cleaning result.

• Fig.1 einen schematischen Aufbau einer erfindungsgemäßen Geschirrspülmaschine.

An embodiment of the invention will be explained in more detail with reference to an accompanying figure. She shows:

• Fig.1 a schematic structure of a dishwasher according to the invention.

In Fig. 1 a dishwasher 1 is shown with a housing, which corresponds to the structure of a conventional household appliance dishwasher known per se. In addition, the dishwasher 1 has a metering system 2, which is arranged outside the housing of the dishwasher 1.

The metering system has two pumps 3 and 4, and two storage tanks 5 and 6. Each of the pumps 3 and 4 has a control with the control modules 7 and 8.

A first reservoir 5 has as a first component a strong alkaline solution, with a pH greater than pH = 12.

A second reservoir 6 has as a second component a solution with 30 wt.% Hydrogen peroxide, as an oxidizing agent.

These two components form the multi-component detergent in the present preferred embodiment.

From each of the two storage containers 5 and 6, a respective line runs to the pumps 3 and 4 and leads from there into the interior of the dishwasher 1.

The cleaning performance of a dishwasher usually depends on four factors, which interact. This concerns the rinsing time, the mechanical energy which acts on a washware to be cleaned by the action of a rinsing agent jet, the temperature of the rinsing agent and the chemical composition of the rinsing agent.

If it now comes to rinse water is first passed into the interior or washing compartment of the dishwasher 1. Depending on the washing program, this water may have different temperatures. Thus, a normal rinse is usually carried out at temperatures between 55-70 ° C and a rinse cycle at temperatures of 65-85 ° C.

During the rinse cycle, the strongly alkaline solution is sucked in by the dosing system 2 by means of the pump 3 and the controller 7 and added to the rinsing solution, also called rinsing liquor. By addition of strongly alkaline solution, the rinsing liquor has a pH of pH = 12 to pH = 13.

Subsequently, the metered addition of the 30% hydrogen peroxide solution to the alkaline washing liquor. This takes place about 60 seconds after the addition of the alkaline solution.

By sequencing seeding first of the alkaline solution and then the hydrogen peroxide solution in the rinsing liquor, the hydrogen peroxide on the surface of the dishes can work optimally. This will be a rinse result achieved, which has a better cleaning effect compared to conventional one-component detergents.

The following investigations and their results were carried out according to the EU Ecolabel, ie using the so-called IKW method. Here, a one-component reference detergent was compared as a laboratory sample of the designation IEC-B with the two-component machine dishwashing detergent described above.

The water hardness in both cases was 8-10 ° d (degree of German hardness). In both cases, 3 ml of the rinse aid IEC 436 Type III was used. From the one-component reference detergent 20 g were added to the wash liquor. Of the two-component rinsing agent, 40 g of the first components, ie the strongly alkaline solution and 10 g of the second components, ie the hydrogen peroxide solution, were added to the rinsing liquor.

The investigations were carried out with the dishwasher Miele G 651 SC with the program "55 ° C universal plus". The loading dirt was 50 g per rinse. A total of 5 comparative measurements were carried out and an average was formed.

• Beispiel 1: Anschmutzungsart: Haferbrei
  zweikomponentiges Spülmittel: 8,6
  einkomponentiges Referenz-Spülmittel: 8,8
• Beispiel 2: Anschmutzungsart: angebranntes Hackfleisch
  zweikomponentiges Spülmittel: 8,9
  einkomponentiges Referenz-Spülmittel: 2,4
• Beispiel 3: Anschmutzungsart: angebrannte Milch
  zweikomponentiges Spülmittel: 8,3
  einkomponentiges Referenz-Spülmittel: 7,9
• Beispiel 4: Anschmutzungsart: Tee
  zweikomponentiges Spülmittel: 8,9
  einkomponentiges Referenz-Spülmittel: 5,4

The following reviews of the cleanliness of the dishes, here glass and porcelain goods, was done visually with a rating scale 1-10, where 10 is to be evaluated as - completely clean.

• Example 1: Soil Type: Oatmeal Porridge
  two-component rinse aid: 8.6
  one-component reference rinse: 8.8
• Example 2: soiling type: burned minced meat
  two-component detergent: 8.9
  one-component reference detergent: 2,4
• Example 3: soiling: burnt milk
  two-component rinse aid: 8.3
  one-component reference detergent: 7.9
• Example 4: Soil Type: Tea
  two-component detergent: 8.9
  one-component reference detergent: 5.4

• Beispiel 5: Ei/Milch
  zweikomponentiges Spülmittel: 5
  einkomponentiges Referenz-Spülmittel: 6
• Beispiel 6: Eigelb
  zweikomponentiges Spülmittel: 14
  einkomponentiges Referenz-Spülmittel: 8
• Beispiel 7: Stärke-Mix
  zweikomponentiges Spülmittel: 96
  einkomponentiges Referenz-Spülmittel: 90

The following evaluations of the cleanliness of the items to be washed were carried out gravimetrically, ie by weighing soiled stainless steel plates before and after the respective cleaning cycle, whereby 100 should be regarded as - completely clean.

• Example 5: egg / milk
  two-component rinsing agent: 5
  one-component reference detergent: 6
• Example 6: egg yolk
  two-component rinsing agent: 14
  one-component reference detergent: 8
• Example 7: starch mix
  two-component rinse aid: 96
  one-component reference detergent: 90

The dosing system described above in connection with the two-component rinsing agent can, as already described, be used in conventional household dishwashers. However, the two-component detergent, u.a. also due to the low exposure time of the oxidant better cleaning results over other one-component cleaning agents. Thus, the described two-component detergent and dosing can also be used in industrial dishwashers, as they u.a. used in large kitchens, old people's homes or hospitals.

The use concentration of the first components, ie the alkaline solution, in wash liquors with soft to medium water hardnesses, ie up to about 14 ° dH or less, is 1 to 2 g / L.

The preferred use concentration of the second components, ie the oxidative solution, in rinsing liquors of any water hardness, is 0.5-1 g / L. The two-component detergent is compatible with the material, suitable for rinsing liquors of any water hardness and is free of nitrilotriacetic acid and ethylenediaminetetraacetic acid derivatives, phosphates and chlorine compounds.

LIST OF REFERENCE NUMBERS

1. 1 dishwasher
2. 2 dosing system
3. 3 pump
4. 4 pump
5. 5 storage containers
6. 6 reservoir
7. 7 control module
8. 8 control module

Claims (4)

1. Method for operating a dishwasher (1) as a domestic dishwasher and/or industrial dishwasher, but not as a flight-type dishwasher, for cleaning dishes by machine, said method comprising the following steps:

   A) metering a strongly alkaline solution having a pH greater than pH = 12 into a wash liquor, wherein the concentration of metered alkaline solution in the wash liquor is 1 to 2 g/l for a water hardness of less than or equal to 14°dH in order to dissolve dirt on the dishes, and

   B) metering a hydrogen peroxide-containing solution into the wash liquor,
   wherein the metering of a hydrogen peroxide-containing solution into the wash liquor starts 40 seconds to two minutes later than the metering of the strongly alkaline solution into the wash liquor, and
   the metering takes place by controlling a first pump (3), for metering the strongly alkaline solution, and a second pump (4), for metering the oxidizing agent-containing solution.
2. Method according to claim 1, characterized in that the metering of the strongly alkaline solution, according to step A, and the metering of the hydrogen peroxide-containing solution, according to step B, take place by means of a metering system (2).
3. Method according to claim 1 or 2, characterized in that the concentration of metered hydrogen peroxide-containing solution in the wash liquor is 0.5 to 1 g/l.
4. Method according to one of the preceding claims, characterized in that the ratio of hydrogen peroxide-containing solution to alkaline solution during the metering is 1:1 to 1:8.

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