EP1657297B1 - Method for washing up - Google Patents

Abstract

Cleaning dishes in a commercial dishwasher comprises prepurifying by spraying with a prepurifying solution (a), primary cleaning and rinsing, where (a) comprises at least an enzymatic component and at least one complex binder.

Description

1. a) Vorreinigen durch Besprühen mit einer Reinigungslösung;
2. b) Hauptreinigen;
3. c) Nachspülen.

The present invention relates to a method for cleaning dishes in a commercial dishwasher, comprising the steps of:

1. a) pre-cleaning by spraying with a cleaning solution;
2. b) main cleaning;
3. c) Rinse.

The automatic cleaning of dishes is widespread in both the private and commercial sector. To remove even dried, baked and / or dye, protein or starch-containing food residues, the addition of one or more cleaners to the wash liquor is usually required. These cleaners should also prevent the formation of deposits (such as tannin or lime) due to incomplete cleaning on the dishes or remove any deposits already formed.

Out EP-B-0 578 666 a method for machine dishwashing is known in which the dishes are subjected to a pre-cleaning by spraying an enzyme-containing detergent solution, which is washed off again after a predetermined exposure time in a main cleaning area by the wash liquor.

WO-A-01/14625 discloses a rinsing method in which a first and a second means stored separately are fed directly to the same spray device in any rinse cycle. As agents are any cleaning-active substances such as enzymes, acids, bleach, complexing agents, surfactants, oxidizing agents, active halogen compounds, disinfectants or alkali carriers or mixtures thereof in any combination with each other.

EP-A-0 806 discloses a process for cleaning dishes comprising the steps of: a) pre-cleaning with a solution of an organic acid and / or a complexing agent for alkaline earth ions, b) main cleaning with an enzymatic detergent solution and c) rinsing.

EP-A-0 808 894 discloses a process for cleaning dishes comprising the steps of a) pre-cleaning by spraying with a detergent solution, b) main cleaning and c) rinsing, wherein at least one alkali component and at least one complexing agent are metered separately into the prepurifying solution.

Out Linderer et al. "Machine Dishwashing Studies" 3rd Communication: Strength Dissolution with Various Types of Cleaners "SOFW: soaps, oils, fats, waxes Journal 121 (1995) No. 3, pages 160, 162-164 and 167 and DE-A-42 19 620 For example, cleaning methods for dishwashing in household dishwashers using enzyme-containing detergents are known. Use of complexing agents in the cleaning solution is not disclosed. DE 4219620 discloses a method for detergent addition in household dishwashers wherein an enzyme-containing agent is metered in the pre-rinse cycle.

The present invention has for its object to provide a method for cleaning dishes of the type mentioned, which has a good cleaning effect with economical. Consumption of detergents, in particular the expensive enzyme, has.

• wenigstens eine enzymatische Komponente,
• wenigstens ein Komplexbildner.

The invention solves this problem in that the following components are added separately to the pre-cleaner solution:

• at least one enzymatic component,
• at least one complexing agent.

Hereinafter, some terms used in the invention will be explained.

In a commercial dishwasher, the dishes on a transport device, in particular a conveyor belt, preferably continuously driven by one or more washing and / or rinsing tanks. The total residence time of the dishes in the machine is very short compared to domestic dishwashers, it is usually between 30 s and 10 min, preferably 30 s and 5 min, more preferably between 1 and 3 min, often at about 2 min.

The term "pre-cleaning" refers to a process preceding the main cleaning, which does not necessarily have to be the first process step. In the context of the invention, further pre-cleaning steps, which are not defined in claim 1, may be connected upstream. For example, a first pre-cleaning step (pre-rinsing) may be provided to remove coarse contaminants. The pre-cleaning according to the invention differs from possible further pre-cleaning steps and from the main cleaning in each case by the fact that fresh pre-cleaner solution, which is applied directly from corresponding storage containers optionally with the addition of fresh water, is used. When pre-cleaning according to the invention therefore no solution is sprayed, which has already been in contact with the dishes. When pre-cleaning according to the invention, therefore, in particular not wash liquor is circulated to a wash tank and sprayed several times on the dishes.

The term "pre-cleaner solution" refers to the solution actually brought into contact with the dishes by spraying, which is obtained by diluting the components or components of the pre-cleaner with water. These components or components of the pre-cleaner will usually be concentrates.

The term "spraying" or "spraying" means bringing the precleaner solution into contact with the dishes such that it is at least mostly wetted by the precleaner solution. It is preferably a finely divided spraying. In a finely divided spraying the pre-cleaner solution is sprayed in small droplets (such as fog-like), the droplets wet the bowl surface and exert no or at most a very low mechanical cleaning effect on the dishes. The spray quantities during finely distributed spraying are preferably 10 to 100 l pre-cleaner solution per h, preferably 10 to 50 l / h, more preferably about 30 l / h. The water consumption via the direct spray system is 5-10% of the total water consumption of the dishwasher. The residence time of the dishes in the pre-cleaner zone (and thus the duration of pre-cleaning is preferably 2 to 60 s, more preferably 2 to 20 s, often in the range 2 to 10 s, for example about 5 s.

The term "separate dosing into the precleaner solution" means that the precleaner solution is prepared from at least the two constituents enzymatic component and complexing agent by mixing in a diluent. Preferably, it is diluted with water. For mixing, fresh, unused components and fresh water (tap water or demineralized water) are used. The mixing is preferably done immediately before spraying on the dishes. "Immediate" in this context means that no supply of pre-cleaner solution is applied, but that during operation of the dishwasher and during the spraying of the pre-cleaner solution, the ingredients are mixed together as needed in the appropriate concentration. As a rule, then lies between the mixing of the components and the spraying a period of at most a few seconds, for example, 0.1 to 30 s, preferably 0.1 to 5 s. The time is determined primarily by the length of the liquid lines of the pre-cleaner solution in the machine and the flow velocity of the components and the water. The separate dosing can be done by metered addition of the components in a premix tank, the premix tank then feeds the spray nozzle or the spray nozzles. Such a premix tank is not a reservoir, it merely serves the greatest possible thorough mixing of the two components and the water before feeding the spray nozzles. The size of the premix tank is such that its contents are completely exchanged during the operation of the spray nozzles within a short period of time of a few seconds to a few minutes (for example, between 2 seconds and 1 minute), so that it is possible to quickly adjust the concentrations of the components to changing conditions. However, it is also possible to feed the precleaner components directly into the feed water line for dosing with a metering pump, which feeds the spray nozzles. Finally, it is also possible that the different components or components of the pre-cleaner solution are sprayed from separate spray nozzles and unite only in situ directly on the harness to the pre-cleaner solution. This possibility is less preferred.

The term "main cleaning" refers to an adjoining the pre-cleaning process in which the dishes are over-washed and / or lapped by a wash liquor. During the main cleaning, this wash liquor is circulated and sprayed onto the dishes at a relatively high throughput (preferably with hard and mechanically spraying jets on the dishes). As a result of the Umwälzvorganges the used wash liquor comes several times with dishes in contact before it overflows (usually contrary to the conveying direction of the dishes) in the next tank and is replaced in this way. The circulated amount of wash liquor may for example be between 300 and 2000 l / h. As a cleaner in this wash liquor can only be sprayed in the pre-cleaning step pre-cleaner solution, which is diluted accordingly by the wash liquor, use. However, it is also possible to additionally meter in other cleaners of the wash liquor which contain customary constituents such as, for example, surfactants, disinfectants and conventional additives and auxiliaries such as, for example, solubilizers, defoamers, fragrances, dyes, thickeners, preservatives and hardness dispersants. In this context, let It should be noted that the listing of the constituents of the precleaner solution in claim 1 is not exhaustive, the substances or auxiliaries mentioned can likewise be contained in components of the precleaner or be added to the precleaner solution.

The term "rinsing" includes all subsequent to the main cleaning invention cleaning and / or rinsing steps. In the context of the invention, it is conceivable that the main cleaning is followed by another main cleaning step with another cleaner. As a rule, however, the main cleaning agent mentioned in claim 1 as step b) will immediately be followed by rinsing (usually with a customary rinse-aid) and possibly also a (further) rinsing with water. All of these variants are encompassed by the term "rinsing" used in claim 1.

An enzymatic component is a component that has an enzyme. Most enzymes have an optimal effect in the weakly acidic to slightly basic pH range.

A complexing agent in the context of the invention is any substance which can keep the hardness of the water constituting metal ions (especially alkaline earth ions) by complex formation in solution.

The invention is based on the surprising finding that the individual, needs-based dosage of enzymatic component on the one hand and complexing agent on the other hand in the aufzusprühende pre-cleaning a comparison with the known from the prior art method in which the complexing agent is added to the main cleaning tank, improved cleaning effect at the same time economical consumption of cleaner (especially both enzymes and complexing agents) allows. The invention has recognized that, in contrast to the technical teaching of the prior art, the enzymes do not develop their full effectiveness first in the wash cycle, but surprisingly significantly improve the cleaning action as part of the sprayed pre-cleaner solution in combination with the enzymatic component. The reason for this cleaning-supporting action of the complexing agent is not conclusively clarified, but the inventors suspect that the complexing agent reduces the adhesion of the contaminants, thus facilitating the penetration of the enzymatic component into the contaminants and thus improving the degradation and detachment of the contaminants , This is especially true for nitrogen-containing complexing agents.

It has been shown that the consumption of enzymatic component and complexing agent is lower if, according to the invention, both components are metered separately according to the actual requirement. In general, you will make the added amount of enzymatic component on the degree of contamination of the dishes, while the complexing agent is usually added depending on the hardness of the water used.

According to an advantageous embodiment of the invention, the pre-cleaner solution has a content of proteases in the range of 0.005 to 0.125 Anson units per 1 l of solution.

According to a further, particularly advantageous embodiment of the invention, the prepurifier solution has a content of amylases in the range of 0.1 to 6 kilo-novo units per 1 l precleaner solution, preferably 0.15 to 2.0 kilo-novo units per 1 l precleaner solution.

According to a further advantageous embodiment of the invention, the pre-cleaner solution has a pH in the range of 7 to 11, preferably 8 to 10, suitable for this buffer systems of organic or inorganic nature.

• Aminopolycarbonsäuren, Hydroxycarbonsäuren, Phosphonsäuren sowie die Salze der vorgenannten Säuren.

The complexing agents used are preferably chelating agents. For the purposes of the invention are all substances that can form chelate-like coordination compounds with metals (especially alkaline earth metals such as calcium and magnesium). Well suited chelating agents are:

• Aminopolycarboxylic acids, hydroxycarboxylic acids, phosphonic acids and the salts of the abovementioned acids.

As already mentioned, the enumeration made in claim 1 of the components of the pre-cleaner solution is not exhaustive. Within the scope of the invention, a surfactant component may, for example, be metered into the precleaner solution. The term "surfactant component" refers to any surfactant-containing substances. Surfactants in the sense of the invention are all substances which can lower the interfacial tension of an aqueous solution. Anionic, cationic, nonionic and amphoteric surfactants are useful. Surfactants which can be used are described in Römpps Chemielexikon, 9.Aufl., Vol. 6, p. 4495 et seq., Under the heading "Surfactants" and in Ullmanns Encyclopedia of Industrial Chemistry, 5.Aufl., Vol.8, p.315 et seq the keyword "detergents" listed. Nonionic or amphoteric surfactants are preferably used, for example surfactants from the class of fatty alkoxylates and N-alkyl-aminocarboxylate. In this context, the disodium salt or dipotassium salt of capryliminodipropionic acid may be mentioned by way of example. The addition of surfactant lowers the surface tension of the pre-cleaner solution and improves and accelerates the cleaning by faster infiltration and separation of dirt deposits and by emulsification in the wash liquor during the subsequent main cleaning. The addition of surfactant can in particular the cleaning of rough surfaces (For example, used plastic dishes) improve, since the penetration capacity of the pre-cleaner solution is improved in the roughened plastic surface. According to a further advantageous embodiment of the invention, the prepurifier solution octylpyrrolidone, in particular N-Co _8- C ₁₂ -alkylpyrrolidone, which improve the efficiency of the enzymes.

The pH of the sprayed pre-cleaner solution is 7 to 11, preferably 8 to 10. Alternatively, the pH pre-cleaner solution has a pH of 6.5 to 7.5. The proportion of complexing agent in the sprayed pre-cleaner solution is preferably 0.05 to 5 wt .-%, more preferably 0.05 to 3 wt .-%, more preferably 0.1 to 2 wt .-%.

For the main cleaning, the addition of a separate main cleaner will not be required as a rule, since the Vorreinigerbestandteile rinsed off the dishes during the main cleaning dissolve in the wash liquor and develop a sufficient cleaning effect. The complexing agent metered separately into the precleaner solution according to the invention ensures, during the main cleaning, that residual hardness present in the wash liquor is complexed and does not form undesired deposits or deposits. In the context of the invention, however, the addition of a separate main cleaner during the main cleaning step is alternatively possible.

The invention will be explained below with reference to an embodiment.

The constituents enzyme component and complexing agent for metering into the precleaner solution have the following composition:

enzyme component

Alkali / amine HEDM-phosphonate 0.1% PAS NA salt 0.1% Sodium cumene 7.2% triethanolamine 6.5% Propylene glycol 1.2 10.0% Alkali / amine citrate 3.8% -octylpyrrolidone 0.9% PPG-4 Laureth-2 10.0% enzyme protein <0.1% water ad 100%

complexing

• 40% NTA solution

To carry out the cleaning process, a Stierlen belt type dishwasher (3-tank, 2 tanks and 1/2 tank) was used. The machine was fed with softened Hamburg city water (residual hardness <1 ° dH). The amount of filling water of the machine was 2 x 125 1, the Nachspülwassermenge 600 l / h. Before the first cleaning tank, a spraying system was installed for spraying the pre-cleaner solution, which was operated at a throughput of 30 l / h.

The residence times of the dishes in the pre-rinsing or Vorabräumbereich located before the spray system was 30 s, in the spray area 5 s, in the subsequent main cleaning area 95 s. The temperatures in the pre-clearance range were 45 ° C to 55 ° C, in the two main cleaning tanks 60 ° C to 65 ° C, the temperature in the final rinse tank was 70 C to 85 ° C.

The filling quantity of 250 l filled before the machine was put into operation was admixed with 2.5 ml of enzyme component and 0.5 ml of complexing agent
In order to maintain this enzyme and complexing agent concentration in the filling water at a Nachspülwassermenge of 360 l / h during operation of the dishwasher, 288 to 324 ml of complexing agent per hour and 1500 ml of enzyme component per hour had to be added via the spray system. The corresponding amounts of enzyme and complexing agent component were added separately to the pre-spraying water, the concentrations in the pre-treatment solution (at a pre-spraying amount of 30 l / h) were accordingly 0.96 to 1.08% by volume of complexing component and 5.0% by volume. Enzyme component per liter of pre-solution.

A test soiling of Teegerbstoffen on coffee or tea dishes could be completely removed with the specified parameters.

Comparative example

Under otherwise identical conditions as in the example according to the invention, the complexing agent component was metered directly into the first main cleaning tank and not, as provided according to the invention, in the pre-cleaner solution. This procedure corresponds to the technical teaching of the prior art. The visual inspection showed that the test soil with the specified parameters could not be completely removed. To achieve the same cleaning effect (complete removal of the test soil from Teegerbstoffen) was an increase in the supply of complexing agent component via the fresh water supply in the first cleaning tank to 360 ml complexing agent per hour is required. Consumption of the complexing agent component was therefore more than 10% higher with 360 ml instead of 288 to 324 ml.

Claims (10)

1. Method for washing dishes in a commercial dishwasher, having the steps:

   a) prewashing by spraying with a prewashing solution,

   b) main washing,

   c) rinsing,

   characterized in that the following constituents are separately metered into the prewashing solution:

   - at least one enzymatic component,

   - at least one complexing agent.
2. Method according to Claim 1, characterized in that the enzymatic component comprises 0.005 to 0.125 Anson units of one protease or more and/or 0.1 to 6 Kilo-Novo units of one amylase or more per 1 l of prewashing solution.
3. Method according to Claim 1 or 2, characterized in that the enzymatic component has a content of amylases in the range from 0.15 to 2 Kilo-Novo units per 1 l of solution.
4. Method according to one of Claims 1 to 3, characterized in that the complexing agent used is a chelating agent.
5. Method according to Claim 4, characterized in that the chelating agent is selected from the group consisting of:

   NTA; EDTA; gluconic acid; phosphonic acids; N-(2)-hydroxyethyl)iminodiacetic acid; 1,2,3,4-cyclopentanetetracarboxylic acid; citric acid; malic acid; tartaric acid; lactic acid; O-carboxymethyltartronic acid; O-carboxymethyloxysuccinic acid; salts of the aforementioned substances.
6. Method according to one of Claims 1 to 5, characterized in that a surfactant component is additionally metered into the prewashing solution.
7. Method according to one of Claims 1 to 6, characterized in that N-C₈-C₁₂-alkylpyrrolidones are additionally metered into the prewashing solution.
8. Method according to one of Claims 1 to 7, characterized in that the prewashing solution has a pH of from 7 to 11, preferably 8 to 10.
9. Method according to one of Claims 1 to 7, characterized in that the prewashing solution has a pH of from 6.5 to 7.5.
10. Method according to one of Claims 1 to 8, characterized in that the fraction of the complexing agent(s) in the sprayed-on prewashing solution is 0.05-5% by weight, preferably 0.05-3% by weight, further preferably 0.1-2% by weight.