EP0256148A1 - Liquid, granulated or powdery detergent, in particular for dish-washing machines - Google Patents

Abstract

The detergent contains citric acid and non-ionic surfactants.

Description

The present invention relates to a novel cleaning agent, in particular for dishwashers, and its use.

It is known that with occasional, unavoidable technical disturbances in the ion exchange of dishwashers, which serve to soften the water used for cleaning, but also with insufficient dosage of the detergent, especially in the area of the door seals, hose connections and low-flow zones of the machine, i.e. where the surfaces are not exposed to the direct and intensive operating pressure of the cleaning liquor, deposits of dirt, cleaning agent residues and lime will settle over time.

These dirt deposits offer an undesirable breeding ground for putrefaction processes, which are noticeable through an unpleasant odor, especially when the dishwasher is opened after a long period of non-use.

Visually, such impurities make themselves also noticeable by a dull gray image, especially on the bare stainless steel parts of the dishwasher. In addition, these contaminants also damage the sealing materials, especially the doors and hoses.

The commercially available, powdery, alkaline or acidic dishwashing detergents or rinse aids are not suitable or are only insufficiently suitable for cleaning, since they are particularly useful for The detergent dosage required by the intended purpose does not sufficiently detach such deposits, but on the contrary, especially in connection with hard water, lead to an additional failure of "lime soaps".

So far, it has been practically dependent on manual cleaning of such problem areas and soiled surfaces by spraying or brushing with strong, skin-irritating acids, such as hydrochloric acid, formic acid, etc., in which these limescale deposits dissolve, but which, on the other hand, affect the steel surfaces too long attack the machine itself.

The products previously offered for automatic cleaning of dishwashers are largely based on the use of citric acid or other polyvalent and / or hydroxyl-containing carboxylic acids (cf. EP 00 33 111 and DE-A 30 02 789).

Since these acids, preferably citric acid and tartaric acid, have only a medium to weak acidity, so that only a part of their potential acid action is used, and moreover they form calcium compounds which are difficult to dissolve, it was necessary to use relatively large amounts of these compounds in order to achieve satisfactory cleaning effects .

There was therefore a need to find a cleaning agent by which the disruptive documents, in particular from dishwashers, can be removed simply and economically in the shortest possible time without corrosion of the dishwasher itself, in particular of its stainless steel surfaces.

The solution to this problem is described by the claims.

In the unpublished DE-P 35 42 970.4 of the applicant it is described that the cleaning action of citric acid can be enhanced by activating it by adding AlCl₃ or FeCl₃. For the use described there as Liquid sanitary cleaning and decalcifying agents must also contain thickeners. Although such agents dissolve limescale well and are therefore well suited for cleaning plastic and / or cast iron and / or porcelain containers and pipes, these agents cannot be used for cleaning dishwashers because they admit the steel and other metal parts of this machine would attack heavily.

Surprisingly, it has now been shown that the action of citric acid, in particular when used as a detergent in dishwashers, can also be activated by adding amidosulfonic acid and / or aluminum sulfate and that the aqueous solutions thus obtained have a practically non-corrosive effect on stainless steel surfaces. In order to ensure adequate wetting of the mostly fatty deposits, it is necessary to add surfactants to these agents, using appropriate, known, low-foaming, non-ionic surfactants to prevent excessive foaming.

Amidosulfonic acid, as a solid, odorless, almost non-toxic, non-hygroscopic acid, which dissolves very well in water and has a lime-dissolving effect, is very suitable for the activation according to the invention. Aluminum sulfate, which also easily dissolves in water with an acidic reaction, has the advantage of being particularly environmentally friendly in addition to the good activation of citric acid as an inorganic compound. Although activation of citric acid is also observed with additions of 10-20%, optimal activation is observed with additions of 30 - 50%. In addition, the activation of citric acid is less apparent than the acidic effect of the compounds themselves, which leads to an undesired lowering of the pH values of the cleaning liquors in the case of amidosulfonic acid.

Through the use of such agents, on the one hand, a rapid dissolution of the lime and cleaning agent residues and, on the other hand, a reduction of the greasy soiling in dishes dishwashers, which also ensures bacteriologically perfect cleaning. At the same time, the addition of the "activating acids" also prevents the formation of insoluble calcium citrates, which was previously to be feared, especially when using hard rinsing water.

The cleaners according to the invention are in the form of solid, granulated or powder detergents, but can also be brought into liquid form with water or aqueous alcohol for simple metering and handling.

The cleaning agent is composed as follows:
50 parts of citric acid
30-50 parts of amidosulfonic acid and / or aluminum sulfate
0.1-6 parts of low-foaming, non-ionic surfactant and possibly
0-200 parts of water or aqueous alcohol.

In special cases, the cleaning agent can also contain 0.1-3, in particular 0.5-2, parts of colorants and / or fragrances and / or corrosion inhibitors.

Since these substances do not influence the actual cleaning effect, but are only added to improve the appearance and smell, their quantity and selection is not critical. Practically all substances known for this purpose can be used as long as they are resistant and inactive to the other, strongly acidic components. A large number of compounds are known to the person skilled in the art, so that a detailed list is unnecessary.

The surfactants used must be slightly foaming. Therefore, non-ionic surfactants are the most suitable. Adducts of ethylene oxide with alkylphenol with a low degree of ethoxylation have been used as suitable surfactants. Adducts of 1 - 7 moles of ethylene oxide, with native or synthetic fatty alcohols with 10 - 18 carbon atoms or adducts based on oxo alcohols or Adducts of 1-7 moles of ethylene oxide and 1-7 moles of propylene oxide with the corresponding alcohols, as well as ethylene oxide adducts with higher molecular propylene glycols or amines with molecular weights of 1000-3500 are also suitable. The most readily biodegradable derivatives of fatty alcohols or oxo alcohols with ethylene oxide and propylene oxide contents of 2-5 molecules per alcohol molecule are preferably used. Although the surfactants can be added in amounts between 0.1 and 6 parts, an amount of 0.5-2 parts has been found to be the most effective, since on the one hand an adequate fat solution and wetting is achieved and on the other hand the foaming remains minimal.

The products according to the invention are concentrates which are diluted with water for the actual application. For cleaning dishwashers, it has proven advantageous, depending on the degree of soiling, to insert a separate cleaning cycle with the products according to the invention about every 20-30 days, the machine with a quantity of 3-20 g of the agent according to the invention per liter of rinsing water at temperatures between 40 and 60 ° C for at least 5, preferably about 10 - 20 min.

For cleaning in the area of the door seal, which does not come into contact with the flushing water, it is possible e.g. apply a 20% solution manually and wipe or rinse with a damp cloth after the appropriate exposure time. The application in commercial machines is best done with a 10 - 30% solution, with which the surfaces to be cleaned are sprayed. After an exposure time of approx. 10 - 30 min at room temperature, the documents have dissolved and can be rinsed off with clear water.

The acidic cleaners according to the invention dissolve and remove lime and cleaning agent residues and fatty soiling from dishwashers. By activating the citric acid with amidosulfonic acid and / or aluminum sulfate, the dissolution rate of the calcareous soiling becomes more appropriate compared to the use of pure citric acid Concentration increased to two to three times. The use of the activators also prevents the formation of poorly soluble calcium compounds.

In the following examples, the agent according to the invention is described in more detail without the invention being restricted thereby.

Example 1:

60 percent by weight citric acid granulated anhydrous
38 percent by weight of amidosulfonic acid granulated
0.2 percent by weight fragrance
1.8% by weight nonionic surfactant based on alcohol of chain length C 13 / C 15, on which 4 moles of propylene oxide and 2 moles of ethylene oxide are attached.

Example 2:

55 weight percent citric acid granulated anhydrous
42 percent by weight of amidosulfonic acid granulated
1.5% by weight of nonionic surfactant (adduct of 3 mol of ethylene oxide and 3 mol of propylene oxide with oxo alcohols, chain length C 13 / C 15)
0.3 weight percent fragrance
1.2 weight percent corrosion inhibitor.

Example 3:

60 percent by weight citric acid granulated anhydrous
38 weight percent aluminum sulfate granulated
0.2 percent by weight fragrance
1.8 percent by weight nonionic surfactant (adduct of 2 moles of ethylene oxide, 4 moles of propylene oxide with fatty alcohol, chain length 12-18 C atoms)

Example 4:

55 weight percent citric acid granulated anhydrous
42 weight percent aluminum sulfate granulated
1.5% by weight of nonionic surfactant (adduct of 2 moles of ethylene oxide and 4 moles of propylene oxide with oxo alcohol, chain length C 13 / C 15)
0.3 weight percent fragrance
1.2 weight percent corrosion inhibitor

Descaling capacity / cleaning capacity

• a) mit 250 ml eines handelsüblichen Produktes mit
  ca. 18 % Citronensäure monohydrat
  ca. 4 % nichtionischem Tensid
  ca. 18 % Isopropanol
  Rest Wasser
• b) 50 g Reiniger Beispiel 1
• c) 50 g Reiniger Beispiel 3

bei Einsatz der Produkte im Normalprogramm im Reinigungsgang benutzt. Beurteilt wurde nach Ablauf das optische Aussehen des Maschineninnenraums.Dishwashers of the Bosch E 700 type were soiled by introducing 163 g of a mixture consisting of 40 g of oatmeal, 30 g of spinach, 15 g of minced meat, 24 g of egg yolk, 12 g of margarine, 42 g of milk with 5 g of commercial dishwashing detergent . After running through the normal program once, the machines were covered with a gray film. The machines were each prepared accordingly

• a) with 250 ml of a commercial product
  approx. 18% citric acid monohydrate
  approx. 4% non-ionic surfactant
  approx. 18% isopropanol
  Rest of water
• b) 50 g of cleaner example 1
• c) 50 g of cleaner example 3

used when using the products in the normal program in the cleaning cycle. After the expiry, the visual appearance of the machine interior was assessed.

Commercial product: Remains of the gray layer are present
Example 1: Interior optically bare
Example 3: Interior optically bare

• 1. Durch Einsatz handelsübliches Produkt mit ca. 18 % Citronen­säure monohydrat, ca. 4 % nichtionischem Tensid, ca. 18 % Isopropanol. Die Entfernung des Belages benötigte 35 min.
• 2. 20 %iger wäßriger Lösung bei Reiniger Beispiel 1 18 min.
• 3. 20 %iger wäßriger Lösung bei Reiniger Beispiel 3 20 min.

Each time after two months of use of a commercial dishwasher, the deposits formed were removed by spraying the surfaces provided with deposits using the following products:

• 1. By using a commercially available product with approx. 18% citric acid monohydrate, approx. 4% non-ionic surfactant, approx. 18% isopropanol. The removal of the covering took 35 min.
• 2. 20% aqueous solution with cleaner Example 1 18 min.
• 3. 20% aqueous solution with cleaner Example 3 20 min.

Dissolution rate

By activating the citric acid an increase in the dissolution rate is achieved and thus a safe removal of calcareous deposits from dishwashers. In order to dissolve 1 g of calcium carbonate (when 80% of the dissolving capacity has been exhausted), 540 seconds are required when using 10% citric acid solution. necessary. Agents according to the invention according to Examples 1 and 3 have dissolving times of 198 and 190 sec.

Solution behavior

Citric acid alone shows 10% citric acid / calcium carbonate in a system at 90 ° C with a precipitation of 1.75 g / l calcium carbonate. The addition of amidosulfonic acid or aluminum sulfate according to the invention greatly reduces the salt formation (precipitation) of calcium citrate.

Example 1 is able under the same conditions to dissolve 3.8 g / l calcium carbonate as a 10% solution, Example 3 4.0 g calcium carbonate.

4.5 g / l calcium carbonate is dissolved at 60 ° C. with anhydrous citric acid within 90 seconds, using agents according to Example 1 in 50 seconds, using agents according to Example 3 in 70 seconds.

In the cold, 4.5 g of calcium carbonate are dissolved in 1% solution of citric acid in 210, 1% solution of Example 1 in 120, 1% solution of Example 3 in 140 seconds.

The solution of calcium carbonate in 1% citric acid solution already leads to a strong calcium citrate precipitation at a quantity of 5.4 g per liter, while when using cleaner according to system 1, completely clear systems are obtained at 5.4 g, when using example 3 5.4 g of calcium carbonate also kept completely clear in solution.

Claims (5)

1). Liquid, granulated or powder detergent, especially for dishwashers, consisting of
50 parts of citric acid
0.1-6 parts of low-foaming, nonionic surfactant
0-200 parts of water or aqueous monohydric alcohol,
characterized in that
30-50 parts of amidosulfonic acid and / or aluminum sulfate are included. 2.) Composition according to claim 1, characterized in that 0.1 - 3 parts of colorants and / or fragrances and / or corrosion inhibitors are additionally contained. 3.) Composition according to claim 1 or 2, characterized in that the surfactant is contained in an amount of 0.5 - 2 parts. 4.) Agent according to claim 3, characterized in that the surfactant is an ethylene oxide-alkylphenol adduct with 1-7 ethylene oxide units or an ethylene oxide / propylene oxide Fatty alcohol adduct with 1-7 ethylene oxide / propylene oxide units, the fatty alcohol having 10-18 carbon atoms, is contained. 5.) Use of the cleaning agents according to claims 1-4, characterized in that a 0.1-2% aqueous solution at temperatures of 40-60 ° C for at least 5 min. or a 10-30% solution for 10-30 min. at room temperature and then rinse the surface to be cleaned with water.