EP1392807B1 - Cleaning method for removing starch - Google Patents

Abstract

The described cleaning process comprises an alkaline and an acid cleaning step as well as one or more additional alkaline and/or acid cleaning steps, in particular for the mechanical cleaning of crockery in commercial dishwashers, in which primarily deposits of starch can be removed exceptionally well.

Description

The invention is directed to a cleaning method comprising a alkaline and an acidic purification step and one or more others alkaline and / or acidic cleaning steps, in particular for mechanical Dishwashing in commercial dishwashers, in particular Starch deposits are excellently removable.

Commercial cleaning machines contain depending on the type and application usually several tanks arranged one behind the other, from which rinsing resp. Wash liquor is sprayed against the laundry passing through the machine. The Tanks are usually cascaded together, the rinsing or Wash the tanks one by one from the laundry outlet end to the laundry inlet end goes through. At the outlet end, the machines are usually Fresh water supplied. The required amount of detergent is in at least one dosing tank also called dosing tank dosed. Usually, the addition of detergent is done automatically in Dependence on the conductivity or the pH of the wash liquor or optionally also by means of a time-controlled or clock-controlled metering pump. It may also be possible that a separate dosage of several components takes place. For example, it happens that a base based alkaline solution an aqueous alkali hydroxide solution is presented. To this basic solution can then be added as needed one or more additives. The Dosage of these additives is usually proportional to the addition of the base liquor or timed. If desired, the dosage of the additives can also depending on the timing of the laundry through the machine befördemden Chain done. Furthermore, a dosage of additives or the Increasing the additive concentration due to the detection of the share Additive in the base liquor via sensory detection of a tracer in the Additive is included, possible.

With the cleaning agents used in practice can be in the usual Detergent concentration starch deposits that adhere to the laundry, im Frame of the usual machine cleaning in a cleaning machine often do not prevent and do not remove existing starch deposits.

In the field of cleaning of dishes is therefore in certain temporal Intervals the starch deposits containing dishes of a so-called Basic cleaning. With such a basic cleaning, in the rinsing or wash liquor compared to normal rinsing significantly increased Concentration of cleaning agent set. Another alternative exists therein, in the course of a usual dishwashing cycle on the dishes to spray a highly concentrated alkaline detergent. Besides it is also possible to carry out a manual basic cleaning.

From DE-OS 17 28 093 it is for cleaning dishes in household dishwashers known for the removal of starch deposits on the Dishes to the rinse water to add a rinse aid along with amylase. If desired, in addition to the amylase also protease or lipase be added to the rinse aid.

Likewise, from DE-AS 12 85 087 a method for mechanical Dishwashing is known in which in the main rinse an alkaline Detergent and rinsing and optionally pre-rinsing a enzyme-containing, in particular amylase-containing, Nachspütmittel in the Dishwasher is dosed. This happens to be in the rinse and if necessary, remove starch from the dishwashing cycle.

From WO 94/27488 a method is known in which a cleaning agent Low alkaline cleaner, especially based on phosphate or Nitrilotriacetic acid or its salts (NTA), and as an additional active ingredient an enzyme, preferably carbohydrate degrading enzyme containing, in particular Amylasehaltiger, detergent booster are metered.

It was found that a low alkaline cleaner in the usual concentration in Connection with an enzyme-containing cleaning booster also in the in commercial dishwashers usual short contact times from 10 to 180 seconds to an excellent removal and inhibition of the Starch buildup on the harness leads.

In contrast, the object of the present invention was to provide a solution create when cleaning in commercial cleaning machines or even in Household machines of the formation of a starch coating on the Wash laundry sustainably prevented and / or degrades existing starch coverings, or and not necessarily the use of enzymes, bleaches, or extremely high alkalinity.

Accordingly, the subject of the present invention is a A cleaning method according to claim 1 comprising an alkaline and an acidic Purification step and one or more other alkaline and / or acidic Cleaning steps, in particular for machine dishwashing in commercial dishwashers.

From WO 98/30673 a dish-cleaning process is already known, in a first and a second cleaning agent are used and the one one detergent and one alkaline pH, wherein before, between and after the application of said Cleaning agent is rinsed in each case with water. This named method should be used in a preferred manner to a rapid disinfection of the Dishes to reach. This differs from this known method present invention clearly. While WO 98/30673 of an alkaline and speaks an acidic cleaning step, the present invention is based a process in which two purification steps in a uniform pH range take place, which is in the acidic or alkaline pH range and at least a third purification step is carried out at opposite pH. This in the WO 98130673 in no way described or recognized principle leads to unexpected results during cleaning, especially during removal of starch deposits. The observed effect, which in the examples of this Application is clarified goes beyond the effect that a professional at Adding another cleaning step would have expected.

Apart from that, in WO 98/30673, the pH change in none Way associated with improving the removal of Starch deposits seen. Thus, the task, which is the present Invention, in a completely different direction and also comes to another Result. During a procedure involving two purification steps opposite pH value underlies mediocre successes in the Removal of starch deposits leads provides the inventive method significantly better results. In which The process according to the invention follows at least one alkaline purification step an acidic cleaning step and this acidic cleaning step alkaline cleaning step with the proviso that at least in total three and preferably not more than eight purification steps are. In the context of the method according to the invention the first of the cleaning steps mentioned is an alkaline cleaning step.

For the process according to the invention it is particularly preferred that in alkaline step and / or not cleaned in an acidic step with the concentrates but with dilute solutions.

Thus, in the inventive method is preferred that in the or alkaline cleaning steps the surface to be cleaned with one or several aqueous cleaning solutions is brought into contact, the between 0.1 and 4 wt .-% of an alkali carrier, preferably a hydroxide selected from sodium, potassium hydroxide or mixtures thereof. The pH of the alkaline purification step is more than 9 preferred On the other hand, it is not necessary for the alkalinity to be higher than 13 is.

As further preferred alkali carriers, in addition to or instead of hydroxides, selected from sodium and potassium hydroxide are exemplified alkali metal silicates, Ethanolamines such as triethanolamine, diethanolamine and monoethanolamine, as well as Alkaline carbonates alkali carrier, preferably a hydroxide selected from Called sodium, potassium hydroxide. Of course, other alkali carriers, be used, since it depends primarily on the increase of the pH.

Likewise, it is preferred in the inventive method that in the or the acidic cleaning steps the surface to be cleaned with one or several aqueous cleaning solutions is brought into contact, the between 0.1 and 10 wt .-%, particularly preferably between 0.1 and 5 wt .-% of one or contain more acids.The pH of the acidic purification step is less than 5, preferably under 2. The preferred acids are selected from mineral and / or organic acids and whole sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, Formic acid, acetic acid, glycolic acid, citric acid, maleic acid, lactic acid, Gluconic acid, alkylsulfonic acid, amidosulfonic acid, succinic acid, glutaric acid, Adipic acid, phosphonic acids, polyacrylic acids or mixtures thereof are.

It is particularly preferred if the said acid is a component with complexing properties.

Preferably, the acidic purification steps of the According to the invention, the surface to be cleaned with one or several aqueous cleaning solutions brought into contact, at least a corrosion inhibitor and / or a conventional complexing agent, especially preferably selected from the phosphonic acids, in particular Dioctylphosphonic acid. In a further preferred embodiment of the invention Procedure is the temperature of said cleaning solutions between 35 and 80 ° C. In addition, it is preferred that after the last cleaning step the surface to be cleaned with a preferably acidic or neutral adjusted aqueous solution containing at least one Rinse aid component, is treated.

Preferably, the time required for said cleaning steps of inventive method each between 10 seconds and 30 minutes. It should be considered in particular whether the inventive method used in a household or commercial machine. Due to the in The practice specified requirements is the time required per cleaning step in commercial machines preferably between 10 seconds and 10 minutes. For household appliances, however, values of 1 to 30 minutes per Cleaning step usual.

As already stated several times that is Use of process according to the invention for starch removal of surfaces. In addition, it has been found that the inventive method Removal of mineral impurities is particularly successful. Especially for residues, such as coffee or tea residues, the proportions of mineral Contain impurities, the inventive method can be advantageous apply. Furthermore, the process according to the invention preferably finds the cleaning of dishes in the household and particularly preferably in the commercial area application.

It should also be stated that it especially it is preferred that the former in the process order alkaline step having lower pH than the later in the process order alkaline step. This is beneficial to the consumption at a meantime to keep the acidic step as small as possible.

The inventive method can be used with multi-tank or single-tank machines be performed.

For machines with a tank, the acidic component is preferably over dosed the rinse aid. The main cleaning bath is preferably alkaline. Such an embodiment of the method according to the invention is also in Use of household machines preferred.

The inventive method can in a commercial Dishwasher be performed by, which contains several tanks, in a known manner cascaded together and from which rinse or wash liquor sprayed against the dishes, then back into the tanks expire, the tanks, due to a method according to the invention are provided for one or more acidic purification steps, from consist of acid-resistant material and / or with acid-resistant material are lined.

In addition, the inventive method in a single-tank washing machine be guided by, for example, a household dishwasher, for a inventive method is suitable, and due to the inventive method with acidic cleaning solutions in contact existing places consists of acid-resistant material and / or with acid-resistant material is lined, especially if not It is foreseeable that these sites would later come into contact with alkaline agents come.

Examples

a) 1 Minute reinigen mit einer 0,3 Gew.-%igen wäßrigen Lösung eines üblichen gleichbleibenden alkalischen Reinigungsmittels (ca. 17 Gew.% Alkalihydroxid, 14 Gew.% Tripolyphosphat und 1,5 Gew.% Alkalihypochlorit sowie ca. 1 Gew.% Alkali-Silikat und Rest Wasser).

b) Flächendeckendes Einsprühen der Teller mit von Versuch zu Versuch andersartiger Ansprühlösungen, deren Zusammensetzung in Tabelle 1 näher beschrieben ist.

c) 30 Sekunden einwirken lassen der aufgetragenen Ansprühlösung.

d) 2 Minuten reinigen mit einer Lösung gemäß a).
Die Reinigungs- und Ansprühlösungen wurden auf Basis von enthärtetem Wasser zur Verfügung gestellt. Die Reinigungstemperatur in der Krefft® Eintank-Geschirrspülmaschine betrug 60 °C.

Per experiment, 10 new, dry food plates are soiled at room temperature according to a standardized starch contamination testing method. For this purpose, a composition containing about 6% aqueous corn starch is cooled after boiling to 75 ° C and applied about 4 ml per plate with a brush. The thus treated plates are allowed to stand for at least 3 hours and then allowed to dry the plates for 16 hours at about 100 ° C. After cooling the plates, comparative tests were carried out in a Krefft® single-tank dishwasher according to the following scheme.

a) Clean for 1 minute with a 0.3 wt .-% aqueous solution of a conventional constant alkaline cleaning agent (about 17 wt.% Alkali hydroxide, 14 wt.% Tripolyphosphat and 1.5 wt.% Alkalihypochlorit and about 1 wt. % Alkali silicate and balance water).

b) area-wide spraying of the plates with try-to-try different types of solution, the composition of which is described in more detail in Table 1.

c) Allow to work for 30 seconds on the applied projection solution.

d) purify for 2 minutes with a solution according to a).
The cleaning and rinsing solutions were provided on the basis of softened water. The cleaning temperature in the Krefft® single tank dishwasher was 60 ° C.

Initially 4 experiments were carried out according to the scheme described, wherein the composition of the cleaning solutions a) and d) maintained and only the elevation solution was changed from experiment to experiment.

The cleaning results were, depending on the cleaning success with numbers of 1 (no cleaning success recognizable) to 10 (complete removal of the Impurities).

The results of the four experiments are shown in Table 1. Cleaning results in tests according to the scheme described, wherein only the Ansprühlösung was changed from experiment to experiment attempt Ansprühlösung Evaluation of the cleaning performance 1 1% NaOH 4.6 2 0.3 g / l perzyme 1.2 3 1% methanesulfonic acid 70% 9.5 4 water 1.2

As can be seen from Table 1, by far the best Cleaning results achieved in experiment 3. In experiment 3 came as a solution a methanesulfonic acid solution is used. The cleaning principle existed for So this very advantageous case in that first alkaline, then acidic and was then cleaned again alkaline.

Further investigations showed that the cleaning performance of the acidic pH is essential and the type of acid used is subordinate Meaning is. Thus, when using equivalent amounts of phosphoric acid in experiment 3 in exchange with methanesulfonic a similarly good Cleaning result achieved, as with methanesulfonic acid.

Claims (9)

1. A method of cleaning dishes in the household or in the commercial sector, said method comprising an alkaline and an acid cleaning step, as well as one or more additional alkaline and/or acid cleaning steps, characterized in that

   a) a first alkaline cleaning step using an aqueous cleaning solution which has a pH value above 9 is followed by

   b) an acid cleaning step using an aqueous cleaning solution which has a pH value below 5 and subsequently by

   c) a second alkaline cleaning step using an aqueous cleaning solution analogous to step a), with the proviso that at least three cleaning steps are performed in total.
2. The method according to claim 1, characterized in that the surface to be cleaned in the alkaline cleaning step(s) is contacted with one or more aqueous cleaning solutions including between 0.1 and 4 wt.-% of an alkali carrier, preferably a hydroxide selected from sodium, potassium hydroxide or mixtures thereof.
3. The method according to any of claims 1 or 2, characterized in that the surface to be cleaned in the acid cleaning step(s) is contacted with one or more aqueous cleaning solutions including between 0.1 and 10 wt.-% of one or more acids.
4. The method according to claim 3, characterized in that said acid is a mineral and/or organic acid, preferably selected from sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, glycolic acid, citric acid, maleic acid, lactic acid, gluconic acid, alkylsulfonic acid, amidosulfonic acid, succinic acid, glutaric acid, adipic acid, phosphonic acids, polyacrylic acids, or mixtures thereof.
5. The method according to claim 4, characterized in that said acid is a component having complexing properties.
6. The method according to one or more of claims 2 to 5, characterized in that the temperature of said cleaning solutions is between 35 and 80°C.
7. The method according to one or more of claims 1 to 6, characterized in that subsequent to the final cleaning step, the surface to be cleaned is treated with an aqueous solution, preferably adjusted to acidic or neutral, which includes at least one rinse component.
8. The method according to one or more of claims 1 to 7, characterized in that the time required for the above-mentioned cleaning steps is between 10 seconds and 30 minutes each time.
9. Use of the method according to one or more of claims 1 to 8 for the removal of mineral soilage and/or for the degradation and removal of starch deposited on dishes.