CZ287850B6 - Use of organic redox-active substances in dishwashing preparations and slightly alkaline preparation for machine washing of dishes - Google Patents

Abstract

In the present invention there is disclosed the use of organic redox-active substances being selected from a group comprising diaminopyridines, aminohydroxypyridines, dihydroxypyridines, heterocyclic hydrazones, aminohydroxypyrimidines, dihydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, diaminodihydroxypyrimidines, dihydroxynaphthalenes, naphthols, pyrazolones, hydroxyquinolines, aminoquinolines, primary aromatic amines having in ortho-, meta- or para-position another free hydroxy group or a hydroxy group or amino group being substituted with alkyl groups containing 1 to 4 carbon atoms or with hydroxyalkyl groups having 2 to 4 carbon atoms and a group of di- or trihydroxybenzenes, as a preparation against silver corrosion in preparations for dishwashing in wash machines , particularly a slightly alkaline preparations for dishwashing. In the present invention there is also described the slightly alkaline preparation intended for machine washing of dishes and that contains in addition to usual components the organic redox-active substance in the amount of 0.05 to 6 percent by weight.

Description

The invention relates to the use of organic redox active substances in dishwashing compositions and to a silver corrosion preservative.

BACKGROUND OF THE INVENTION

It is a well-known fact that silver, even if not used, "treats". It is only a matter of time before he gets dark, brownish, bluish to bluish-black spots or changes color in general, and this is, as a general rule, “faded”.

Even when washing table silver in dishwashers, in practice there are still problems in the form of silver treatment and discoloration of its surface. Silver can react to sulfur-containing substances that are dissolved or scattered in the rinsing water, as dishwashing (HGSM) washes food residues, including mustard, peas, eggs, and others. sulfur-containing compounds. Also, much higher machine wash temperatures and longer contact times with sulfur-containing food residues support silver treatment compared to manual washing. In addition, the intensive cleaning process in the dishwasher completely frees the silver surface and makes it more sensitive to chemical influences.

When using active chlorine-containing cleaning agents, the treatment of silver with sulfur-containing compounds can be largely avoided since these compounds are converted to sulfones or sulfates in the secondary reaction by oxidation of sulfide functions.

However, the problem of silver treatment has become current when, in addition to active chlorine compounds, active oxygen compounds such as sodium perborate or sodium percarbonate have been used to remove bleachable contaminants such as tea stains, tea deposits, coffee residues , vegetable dyes, lipstick residues and the like.

These active oxygen compounds are used primarily in modern, weakly alkaline, new generation detergents together with bleach activators. These modern compositions usually consist of the following functional components: a basic component (complexing agent / dispersing agent), an alkali carrier, a bleaching system (bleaching agent + bleach activator), enzymes and surfactants (surfactants).

Silver surfaces react significantly more sensitively to the changed parameters of the new generation chlorine-free, low pH and oxygen bleach activated receptors. In machine washing, these compositions release hydrogen peroxide or active oxygen as a bleaching agent during the cleaning process. The bleaching action of the active oxygen-containing cleaning compositions is enhanced by the bleach activators so that a good bleaching effect is achieved even at low temperatures. In the presence of these bleach activators, peracetic acid is formed as a reactive intermediate. Under these altered washing conditions, in the presence of silver, not only mercury, but also oxide coatings on the silver surfaces are formed as a result of the oxidative action of the peroxides or active oxygen formed. Under high salt load, chlorine-containing coatings may be formed. The silver treatment is further enhanced by the higher residual hardness of the water during the cleaning process.

Preventing the corrosion of silver, i.e. the formation of silver, oxide, or oxide-containing coatings on silver is the subject of numerous publications. Silver corrosion in these treatises is prevented primarily by so-called anti-silver corrosion agents.

- 1 GB 287850 B6

GB-A-1 131 738 discloses alkaline dishwashing compositions containing benzotriazoles as silver corrosion inhibitors. U.S. Pat. No. 3,549,539 discloses strongly alkaline, machine-washable dishwashing compositions which may contain, inter alia, an organic bleach activator perborate as an oxidizing agent. Additives, inter alia, benzotriazole and also ferric chloride, are also recommended as anti-opaque agents. The pH values are preferably 7 to 11.5. European Patent Specifications EP 135 226 and EP 135 227 disclose weakly alkaline, machine-usable dishwashing compositions containing peroxy compounds and activators, which are silver protecting agents, which may include, but are not limited to, benzotriazoles and fatty acids. Finally, it is known from DE-A-4 128 672 that peroxy compounds which are activated by the addition of known organic bleach activators prevent the treatment of silver parts in salt-alkaline cleaning agents.

Unexpectedly, it has now been found that organic redox active substances, in particular inducing or developing compounds, which have not yet been described as silver corrosion protection agents, effectively prevent corrosion of silver in machine dishwashers.

SUMMARY OF THE INVENTION

It is an object of the invention to use organic, redox-active substances as anticorrosive agents in silver dishwashing compositions.

The present invention is based on the use of organic redox active substances from the group of diaminopyridines, aminohydroxypyridines, dihydroxypyridines, heterocyclic hydrazones, aminohydroxypyrimidines, dihydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, diaminodihydroxypyrimidines, diaminodihydroxypyrimidines, , the meta- or para- position have additional hydroxy- or amino-substituted by free or C 1 -C 4 -alkyl or C 2 -C 4 -alkyl, and from the di- or trihydroxybenzene group as silver corrosion agents in detergents dishes.

The present invention also provides a weakly alkaline machine dishwashing composition whose 1% (by weight) solution has a pH of 8 to 11.5, preferably 9 to 10.5, and which contains 15 to 60% by weight, preferably 30 to 50% by weight of the basic water-soluble component, 5 to 25%, preferably 10 to 15% by weight of oxygen-based bleach, 1 to 10% by weight, preferably 2 to 6% by weight of organic bleach activator, and 0.1 to 5% by weight, preferably 0.5 to 2.5% by weight of enzyme, each time based on the total amount of the composition, and a silver corrosion agent comprising, as a silver corrosion agent, an organic redox agent selected from diaminopyridines, aminohydroxypyridines, dihydroxypyridines, heterocyclic hydrazones, aminohydroxy-pyridines, dihydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, diaminodihydroxypyrimidines, dihydroxynaphthalenes, naphthols, pyrrazo hydroxyl-quinolines, amino-quinolines, primary aromatic amines having in the ortho-, meta- or para-position having additional free or C 1 -C 4 -alkyl or C 2 -C 4 -alkyl-hydroxyalkyl groups, or from di- or trihydrobenzenes.

The term 'corrosion' is to be interpreted in its broadest meaning in chemistry, in particular 'corrosion' here means any visually still recognizable change in the surface of the metal, here silver, whether it is, for example, a spot change in color or a large-scale craze.

'Organic redox-active substances' are those organic substances which are susceptible to readily occurring reversible oxidation and / or reduction. Thus, this definition does not include typical complexing agents such as EDTA or hydroxyethane diphosphonic acid and related compounds.

-2GB 287850 B6

As the "organic redox-active substances" as typical according to the invention are, for example, ascorbic acid (vitamin C), indole, methionine (alpha-amino-γ-methylmercaptobutyric acid).

Also suitable are N-mono (C 1 -C 4 alkyl) glycine and N, N'-di- (C 1 -C 4 alkyl) glycine, for example Ν, Ν'-dimethylglycine and 2-phenylglycine.

Certain developing and / or developing compounds known from oxidative dyeing are also particularly suitable.

The organic substances, preferably used to prevent silver corrosion, are compounds selected from the group of diaminopyridines, aminohydroxypyridines, dihydroxypyridines, heterocyclic hydrazones, aminohydroxypyrimidines, dihydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, diaminodines, diaminodine-naphtholines, diaminodihydro-naphtholines which in the ortho-meta- or para-position have further free or C 1 -C 4 alkyl groups or C 2 -C 4 hydroxyalkyl groups substituted by a hydroxy or amino group, and di- or trihydroxybenzenes.

The water-soluble compounds used in the present invention to prevent corrosion of silver are substances of the above groups usually used in oxidative dyes. Examples of such water-soluble compounds are given, for example, in "Verkataraman, The Chemistry of Synthetic dyes, Vol. V, Academic Press New York / London, 1971, pp. 478-495, as well as the literature cited therein. Particularly suitable for preventing silver corrosion are compounds selected from the group of p-hydroxyphenylglycine, 2,4-diaminophenol, 5-chloro-2,3-pyridinediol, 1- (p-aminophenyl) morpholine, pyrocatechin, hydroxyhydroquinone, gellic acid, fluroglucin, pyrogallol .

The organic redox active materials are preferably coated, i.e. they are completely coated with a water impermeable material, but readily soluble at purification temperatures, to prevent premature decomposition or oxidation upon storage. Preferred coating materials to be applied according to known methods, for example, the Sandwik melt coating from the food industry, are paraffins, microwaxes, waxes of natural origin such as carnauba wax, kanutile wax, beeswax, high melting alcohols such as hexadecanol, soaps or fatty acids. In this case, the coating material which is solid at room temperature is applied to the coated material in the molten state, for example by passing fine particles of the coated material in a continuous stream also through a continuously formed mist of molten coating material. The melting point must be chosen such that the coating material is easily dissolved or rapidly melted when the silver anti-corrosion agent is subsequently used in a dishwasher. The melting point should therefore be in the range of between 45 ° C and 65 ° C and most preferably between 50 ° C and 60 ° C in most applications.

However, the above-mentioned organic redox active substances are particularly suitable for preventing silver corrosion when contained in weakly alkaline machine dishwashing detergents. This is all the more surprising because these silver corrosion protection agents are not impaired in their action by the presence of oxygen-based bleaches, usually contained in weakly alkaline cleaning agents.

Therefore, a further object of the invention are weakly alkaline machine dishwashing compositions whose 1% by weight of solutions have a pH of 8 to 11.5, preferably 9 to 10.5, and contain 15 to 60% by weight, preferably 30 to 50 % by weight, preferably 10 to 15% by weight of oxygen-based bleach, 1 to 10% by weight, preferably 2 to 6% by weight of organic bleach activator, 0.1 to 5% by weight, preferably 0.5 to 2.5% by weight In each case, they contain an organic redox-active substance as a silver-corrosion agent. Particularly suitable are ascorbic acid, indole, methionine, N-mono- (C 1 -C 4 alkyl) glycine N, N'-di- (C 1 -C 4 alkyl)

-3C 287850 B6 to 4 carbon atoms) glycine and 2-phenylglycine, in particular developing and / or inducing compounds selected from the group of diaminopyridines, aminohydroxypyridines, heterocyclic hydrazones, aminohydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, diaminodihydroxinols, diaminodihydroxypolines, diaminodihydroxypolines, Aminoquinolines, primary aromatic amines having in the ortho-, meta- or para-position having additional free or C 1 -C 4 alkyl or C 2 -C 4 hydroxyalkyl substituted hydroxy or amino groups, and di- or trihydroxybenzenes.

Preferred dishwashing compositions comprise water-soluble compounds selected from the group consisting of p-hydroxyphenylglycine, 2,4-diaminophenol, 5-chloro-2,3-pyridine, 1- (p-aminophenyl) morpholine, hydroquinone, pyrocatechin, hydroxy-hydroquinone , gallic acid, floroglucin, pyrogallol, and mixtures thereof.

Preferably, the organic redox active compounds are present in the compositions according to the invention in a total amount of 0.05 to 6% by weight, preferably 0.2 to 2.5% by weight, based on the total composition.

Basically, water-soluble components are, in principle, all the components customarily used in dishwashing compositions, for example polymeric alkali metal phosphates, which may be provided in the form of their alkali, neutral or acidic sodium or potassium salts. Examples of this are: tetra-sodium diphosphate, disodium dihydrogen diphosphate, pentane-sodium triphosphate, the so-called sodium hexametaphosphate, and the corresponding potassium salts or mixtures of sodium hexametaphosphate and the corresponding potassium salts or mixtures of sodium and potassium salts. The amounts of phosphate are in the range of up to about 30% by weight based on the total amount of the composition, but preferably the compositions of the invention are free of such phosphates. Other possible water-soluble base components are, for example, organic polymers of natural or synthetic origin, in particular polycarboxylate, which, in particular in hard water systems, act as excipients. Suitable examples are polyacrylic acids and copolymers of maleic anhydride and acrylic acid, as well as sodium salts of these polymeric acids. For example, Sokalan ^R CP 5 and PA 30 are commercially available. BASF, Alcosporse ^R 175 or 177, fy. Alco, LMW ^R 45 N and SPO2 N, fy. Norsohaas. Natural polymers include, for example, oxidized starch (German Patent Application No. 42 28 786.3), and polyamino acids, such as polyglutamic acid or polyaspartic acid, for example from Cygnus or SCHREM.

Other possible basic ingredients are naturally occurring hydroxycarboxylic acids, such as mono- or dihydroxysuccinic acid, alpha-hydroxypropionic acid and gluconic acid. Preferred base ingredients are salts of citric acid, especially sodium citrate. Suitable sodium citrate is anhydrous sodium citrate, preferably sodium citrate dihydrate. Sodium citrate dihydrate can be used as a fine crystalline or coarse crystalline powder. Depending on the pH values set in the compositions according to the invention, acids corresponding to citrate may also be suitable.

Possible oxygen-based bleaching agents are, in particular, sodium percarbonate monohydrate and tetrahydrate. The use of sodium percarbonate has advantages as it has a particularly favorable effect on the corrosive behavior on the glass. The oxygen-based bleaching agent is therefore preferably a percarbonate salt, in particular sodium percarbonate. Since active oxygen only develops its full effect by itself at higher temperatures, so-called bleach activators are used to activate it in a dishwasher. Examples of organic bleach activators are PAG (pentaacetylglucose), DADHT (1,5-diacetyl-2,4-dioxo-hexahydro-1,3,5-triazine) and ISA (isatinic anhydride), but preferably Ν, Ν, Ν ', Ν'-tetraacetylethylenediamine (TAED). In addition, the addition of small amounts of known bleach sterilizers, such as phosphonates, borates or metaborates and metasilicates, as well as magnesium salts such as magnesium sulfate, may also be expedient.

-4GB 287850 B6

For better separation of food residues containing proteins, fat or starch, the dishwashing compositions of the invention contain enzymes such as proteases, amylases, lipases and cellulases, for example proteases such as BLAP ^r 140, phy. Henkel, Optimase ~ M-440 ^{R, R} Optimase ~ M-330, Opticlean ^R M-375, Opticlean ~ M-250 ^R, fy. Solvay Enzymes, Maxacal ^R CX 450.000, Maxapen ^R fy. Ibis, Savinase ^R 4.0 T, 6.0 T, 8.0 T fy. Novo, Esperase ^R T, fy. Ibis and Amylasen, Such as Termamyl ^R 60 T, 90 T, fy. Novo, Amylase-LT ^R fy. Solvay, enzyme, or Maxamyl ^R P 5000, CXT 5000 or 2900, fy. Ibis, lipases such as Lipolase ^R 30 T, fy. Novo, cellulases such as Celluzym ^R 0.7 T, phy. Novo Nordisk. Preferably, the dishwashing compositions comprise proteases and / or amylases.

Preferably, the compositions of the present invention also contain alkali metal carriers contained in conventional weakly alkaline dishwashing compositions such as alkali metal silicates, alkali metal carbonates and / or alkali metal bicarbonates. Alkali metal carriers commonly used include alkali metal carbonates, bicarbonates and silicates with a molar ratio of S1O2 / M2O (M-alkali metal atom) of 1.5: 1 to 2.5: 1. Alkali metal silicates can be present in amounts up to 30% by weight, based on the total amount of the composition. The use of strongly alkali metasilicates as alkali metal carriers is preferably omitted. The alkali metal carrier system used preferably in the compositions of the invention is a mixture of substantially carbonate and bicarbonate, preferably sodium carbonate and sodium bicarbonate, in an amount of up to 60% by weight, preferably 10 to 40% by weight, based on the entire amount of the composition. Depending on which pH is ultimately desired or adjusted, the ratio of carbonate to bicarbonate used varies, but an excess of sodium bicarbonate is usually used, and the weight ratio between bicarbonate and carbonate is usually 1: 1 to 15: 1.

If desired, surfactants, in particular weakly foaming nonionic surfactants, may also be added to the compositions of the invention to better release the fat-containing food residues as wetting agents, as granulating agents or as dispersing agents for better, more homogeneous distribution of the aforementioned anti-corrosion agents. in a rinse bath or silver surface. Their amount is then up to 5% by weight, preferably up to 2% by weight. Extremely non-foaming compounds are usually used. These preferably include alkylpolyethylene glycol-polypropylene glycol ethers containing up to 8 moles of ethylene oxide and propylene oxide units per molecule. However, other non-foaming known nonionic surfactants such as, for example, C12-18 alkylpolyethylene glycol polybutylene glycol ether and up to 8 moles of ethylene oxide and butylene oxide units per molecule, closed-chamber mixed alkyl polyalkylene glycol ethers, but also environmentally foaming, can also be used interesting alkyl polyglycosides of 8 to 14 carbon atoms and in a polymerization stage of about 1 to 4 (e.g. APG ^r 225 and APG ^R 600 from Henkel) and / or alkyl polyethylene glycols of 12 to 14 carbon atoms and 3 to 8 units of ethylene oxide per molecule. Bleached quality should be used, otherwise a brown granulate will form. Also suitable are surfactants from the group of glucamides, such as alkyl-N-methyl glucamides (alkyl = fatty alcohol having a carbon chain length of 6 to 14 carbon atoms). It is particularly advantageous when the surfactants described are used as mixtures, for example combinations of alkyl polyglycosides with fatty alcohol ethoxylates or glucamides with alkyl polyglycosides, etc.

If the detergents are too foaming in use, up to 6% by weight, preferably about 2.5 to 4% by weight, of a suds suppressing compound, preferably from the group of silicone oils, mixtures of silicone oil and hydrophobic silicic acid, paraffin, can be added thereto. oils / guerbetaalcohols, hydrophobized silicic acid, bistearic acid amides, and other known suds suppressors available. Other possible additives are, for example, essential oils.

The dishwashing compositions according to the invention are preferably powdered granular or tableted compositions which can be manufactured in a customary manner, for example, by granulation mixing, roller compaction and / or spray mixing.

-5GB 287850 B6

To produce detergents according to the invention in tablet form, the procedure is preferably such that in a mixer mixing together all ingredients and using conventional tablet presses, for example eccentric presses or presses svystředěným member compresses the compression force in the range of 200.10 ⁵ Pa to 1500.10 ⁵ Pa. In this way, non-brittle yet rapidly dissolving tablets with a flexural strength of generally over 150 N are obtained without problems. Preferably, the tablet thus produced weighs 15 g to 40 g, in particular 20 g to 30 g, with a diameter of 35 mm to 40 mm.

The production of non-dusting, dishwashing detergent machinery for the storage of fixed bulk powders and / or granules of high bulk densities of 750 to 1000 g / l is characterized in that in the first stage of the process the base ingredients are mixed with at least a part of the liquid ingredients to increase the bulk densities of this premix and then, optionally after prior drying, the other components of the dishwashing machine, among which organic redox active substances, are combined with the premix thus obtained.

Since the possible content of alkali metal carbonate strongly affects the alkalinity of the product, the drying must be carried out so that the decomposition of sodium bicarbonate to sodium carbonate is as small as possible or at least as constant as possible. According to the sodium carbonate produced by drying, it would have to be taken into account when formulating the granulate formulation. The low drying temperatures not only counteract the disintegration of sodium bicarbonate, but also increase the solubility of the granular detergent when used. Advantageously, therefore, the drying temperature is an additional air temperature which, on the one hand, should be as low as possible to prevent bicarbonate disintegration and, on the other hand, must be as high as is necessary to obtain a product with good storage properties. Preferably, the drying temperature is about 80 ° C. The granulate itself should not be heated to temperatures above about 60 ° C. In the first part of the mixing process, the base component is generally treated with liquid components in admixture with at least one other component of the dishwashing detergent. For example, a preliminary step in which the base component in admixture with perborate is treated with liquid non-ionic surfactants and / or a fragrance solution is contemplated and mixed intimately. The remaining ingredients are then added and the total mixture is worked up and homogenized in a mixer. The simultaneous use of additional amounts of liquid, in particular the use of additional water, is generally not required here. The resulting mixture of substances is then a free-flowing, non-dusting powder with a desired high bulk density in the range of about 750 to 1000 g / l.

The pre-granules are then mixed with the remaining ingredients of dishwashing detergent, including organic redox active ingredients, to form the finished product. The mixing time in all cases mentioned herein, both in the preliminary mixing step under the influence of the liquid components and in the subsequent final mixing with the other components, is in the range of a few minutes, for example in the range of 1 to 5 minutes.

According to a particular embodiment of the invention, in the production of fine granular grains, it may be expedient to achieve a penetrating stabilization and leveling by dusting the formed granulate grains. Particularly suitable for this are small proportions of powdered water glass or powdered alkali metal carbonate.

Said compositions can be used both in household dishwashers and in dishwashers in operations. They are added manually or by means of suitable dosing devices. The concentration used in the cleaning bath is about 2 to 8 g / l, preferably 2 to 5 g / l.

Usually, the washing program is supplemented by several rinsing steps, followed by rinsing with clean water, and terminated by rinsing with a conventional rinse aid. After drying, not only completely clean and perfect hygiene utensils are obtained, but especially the bright shiny parts of silver cutlery.

-6GB 287850 B6

DETAILED DESCRIPTION OF THE INVENTION

Silver spoons (WMF type, hotel cutlery, Form, Berlin) were cleaned with silver cleaner, de-greased with petrol and dried. Three tablespoons each were then placed in the cutlery basket of the Bosch S712 type dishwasher (HGSM). A cleaning program (65 ° C, 16 dH) was then started and 50 g of impurity 1 as well as 30 g of detergent were dispensed directly into the machine during the cleaning process. After the washing and cleaning procedure was completed, the dishwashers were opened for 10 minutes, the machines then closed again and washing was resumed in the same manner. After the 10th wash cycle, the spoons were removed and rated. To this end, the colors of the shade were rated from 0 to 4:

O = no faintness, = totally weak color to yellow, = stronger color to yellow, = full color to yellow to brown, = violet to black tbsp, see values in the upper left of Tables 1 to 3.

At the same time, the removal of tea stains on porcelain dishes was considered. Here the rating was between 0 and 10, where = no tea removal and 10 = complete tea removal, see the values at the bottom left of Tables 1 to 3.

1) Composition of impurities

Ketchup25 g mustard (extra sharp) 25g roast juice 25g potato starch5 g benzoic acid 1g egg yolk 3 pieces milk0,51 margarine92 g tap water 608 ml.

Tea dirty

In a water treatment boiler, 16 liters of cold tap water (16 ° d) are briefly heated until boiling. 96 g of black tea in a nylon mesh is left to stand for 5 minutes with the lid closed and the tea is transferred to an immersion apparatus with heating and a stirrer.

The tea cups are immersed in the prepared broth in 25 minutes at 70 ° C. The cups are then removed and placed on the baking tray with the opening facing down.

Composition of detergent

First, the following weakly alkaline base product was produced, whose 1% solution (by weight) in distilled water had a pH of 9.5.

56.0% sodium citrate dihydrate

36.1% sodium bicarbonate

6.1% sodium carbonate, anhydrous

1.8% mixture of nonionic surfactants from APG 225 (C 8 -C 10 alkyloligoglycoside) and Dehydol ^R LS ² (C 12 -C 14 fatty alcohol - 2EO - ethoxylate, 1: 1).

Test variations determined by the following recipe were made with this base product. The results are shown in Tables 1 to 3.

up to 86% by weight 5 12% by weight to 10% by weight 0 to 3% by weight% by weight base product sodium percarbonate

TAED pyrocatechin, gallic acid or hydroquinone protease amylase

Table 1

Tea cleaning / silver corrosion protection

Machine: Bosch S712 dosing: 30 g program: 65 ° C Universal water hardness: 16 ° dH tea: 1 = no cleaning = optimal cleaning silver: 0 = no dullness = strong dullness

-8EN 287850 B6

Table 2

Tea cleaning / silver protection against corrosion

Machine: Bosch S712 dosing: 30 g program: 65 ° C Universal water hardness: 16 ° H tea: 1 = no cleaning

- optimum silver cleaning: 0 = no fading = strong fading

-9EN 287850 B6

Table 3

Tea cleaning / silver protection against corrosion

Machine: Bosch S712 dosing: 30 g program: 65 ° C Universal water hardness: 15 ° dH tea: 1 = no cleaning = optimal cleaning silver: 0 = no dullness = strong dullness

-10GB 287850 B6

In addition, dishwashing machines were produced in the following compositions, see Table 4. Compounds A-M were used as anti-corrosion agents in silver:

AND: p-hydroxyphenylglycine B: 2,4-diaminophenol C: 5-chloro-2,3-pyridinediol D: 1- (p-aminophenyl) morpholine E: ascorbic acid F: N-monomethylglycine G: N, N-dimethylglycine H: I: 2-hydroxy-4-aminopyrimidine 2,4-dihydroxy-5-methylpyrimidine TO: indole L: methionine M: 2-phenylglycine

-11GB 287850 B6

Table 4: (all figures in% by weight)

1 2 3 4 5 6 7 8 9 10 soda (sodium carbonate) 27 Mar: 8 26 8 _ 26 8 sodium bicarbonate - - 31 - - 30 - 30 - sodium disilicate 35 20 May - 35 20 May - 35 20 May - 34 sodium citrate dihydrate 40 25.5 44 40 25.5 44 39 25.5 43 39 polycarboxylate (Sokalan CP5 from BASF) 10 10 - 10 10 - 10 10 - 10 sodium percarbonate - 10 10 - 10 10 - 10 10 - sodium perborate monohydrate 7 - - 7 - 7 - - 7 TAED 2 3 2 2 3 2 2 3 2 2 fatty alcohol ethoxylate 0-12-14 carbon atoms (2EO) (Henkel dehydol LS2) 1 0.75 1 1 0.75 1 1 0.75 1 1 8-10 carbon alkyl oligoglycoside (APG 225, Henkel) 1 0.75 1 1 0.75 1 1 0.75 1 1 protease 1.5 1 1 1.5 1 1 1.5 1 1 1.5 amylase 1.5 1 1 1.5 1 1 1.5 1 1 1.5 silver anti-corrosion agent A-M (A) l (B) 1 (C) 1 (D) 1 (E) 2 (F) 2 (G) 2 (H) 2 (AND) 3 (TO) 3 pH of 1% aqueous solution 10.5 11 9.5 10.5 11 9.5 10.5 11 9.5 10.5

Table 4 - continued

11 12 13 14 15 Dec 16 17 18 19 Dec 20 May soda (sodium carbonate) 26 8 25.5 8 26 7 26 sodium bicarbonate - 30 - - 29 - - 29 - - sodium disilicate 19.5 - 34 19 Dec - 34 18.5 - 34 18.5 sodium citrate dihydrate 25 43 38 25 43 38 24 43 38 24 polycarboxylate (Sokalan CP5 from BASF) 10 - 10 10 - 10 10 - 9 10 sodium percarbonate 10 10 - 10 10 - 10 10 - 10 sodium percarbonate monohydrate - - 7 - - 7 - - 7 - TAED 3 2 2 3 2 2 3 2 2 3 fatty alcohol ethoxylate (Dehydol LS2 from Henkel) 0.75 1 1 0.75 1 1 0.75 1 1 0.75 alkyloligoglycoside (APG 225, Fy Henkel) 0.75 1 1 0.75 1 1 0.75 1 1 0.75 protease 1 1 1.5 1 1 1.5 1 1 1.5 1 amylase 1 1 1.5 l AND 1.5 1 1 1.5 1 silver anti-corrosion agent A-M (L) 3 (M) 3 (AND) 4 (B) 4 (C) 4 (D) 4 (E) 5 (F) 5 (G) 5 (H) 5 pH of 1% aqueous solution 11 9.5 10.5 11 9.5 10.5 11 9.5 10.5 11

Silver spoons were generally rated from 0 to 1, which is "no to very foolish". The identical composition, but without the A - D anticorrosive agents, caused silver to yellow to violet tinting on silver spoons (rating 2 to 4).

Electrochemical measurements

Sample preparation:

In the experiments, silver wire (d = 2 mm, 99.99%) was used as the sample material instead of silver cutlery. Sections of approximately 10 cm were cut from this silver wire, and the portion of the sample that had been immersed in the solution to be measured was sanded with Sil sandpaper (600 changes). Subsequently, the samples were rinsed well with double distilled water and any grinding residue, if any, wiped off with a non-scraping substance. This procedure was optionally repeated several times until the sample gave an optically colorless impression. After grinding, the samples were used immediately for measurement to prevent the reaction of metallic silver with laboratory air. The effective solution immersed area of the sample was 0.70 cm ² .

-12GB 287850 B6

Electrolytes and electrodes:

The experiments were carried out in a container made of glass and duralumin metal. The silver wires were used as measuring electrodes. The counter electrode consisted of gold plate (99.99%) with an area of 1 cm ^{1 2} . The electrode Hg / HgO / Olm zNaoH was chosen as the reference electrode with respect to the alkaline electrolytic solutions, which was connected to the electrolyte via a Hober-Luggin capillary. Measurements were made at a content of 5 g / l of pure composition in tap water of 16 ° d and a salt load of approximately 600 mg (dry weight).

To prepare detergent solutions, the weakly alkaline base product (see above) was first dissolved and heated to 65 ° C. Bleach and bleach activator and / or anticorrosive agent were added just prior to measurement. Electrochemical measurements were then performed. In electrochemical experiments, the electrolyte solutions were tempered to 65 ° C and purged with air.

Equipment and reading of measured curves:

After sensing current-voltage curves, the electrode potential was increased at a constant rate, from -0.62 V, relative to a standard hydrogen electrode (SHE). After increasing by a total of 1.1 V, the potential was then reduced at the same rate. To this end, a standard potential consisted of a coupling amplifier, a differential amplifier, an adder and an impedance converter, as well as a functional generator (Prodis 16, by Intelligent Controls CLZ GmbH).

Results:

The characterization of the corrosion behavior was performed on the basis of current-voltage curves. Significant information is given by passing the current-voltage curve to zero (a resting potential that is self-adjusting even without external potential influence) and by increasing the zero-crossing curve (reciprocal of the polarization resistance, see E. Heitz, R. Henkhaus, A. Rahmel, "Korrosionskunde im Experiment" Verlag Chemie (1983), p. 31 ff, H. Kaesch, "Die Korrosion der Metalle", 2nd ed., Springer Verlag (1979), p. 117 ff. The corrosion of silver shifts the potential of zero passage to lower values and the pitch decreases, so the corrosion of silver is greatly reduced by the anti-silver corrosion, which is also electrochemically measurable.

detergent composition zero crossing E (mV) (SHE) zero / diE (mA / V) base product (86%) + 12% percarbonate + 2% hydroquinone 319 0.5

PATENT CLAIMS

Claims (16)

Use of organic redox-active substances from the group of diaminopyridines, aminohydroxypyridines, dihydroxypyridines, heterocyclic hydrazones, aminohydroxypyrimidines, dihydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, diaminodihydroxypyrimidines, hydroxyhydrochinolines, dihydroxyquinaphtholines, dihydroxynaphtholines, dihydroxy-naphtholines or para-position have another hydroxy or amino substituted by free or C 1 -C 4 alkyl or C 2 -C 4 hydroxyalkyl, and from the di- or trihydroxybenzene group as anti-silver corrosion agents in dishwashing compositions. -13GB 287850 B6 Use according to claim 1, wherein the organic redox active is selected from the group of phydroxyphenylglycine, 2,4-diaminophenol, 5-chloro-2,3-pyridinediol, 1- (p-aminophenyl) morpholine, hydroquinone, pyrrocatechin, hydroxyhydroquinone , gallic acid, floroglucin 5 and pyrrogallol. 3. The 1% solution has a pH of 8 to 11.5, preferably 9 to 10.5, and which contains 15 to 60% by weight, preferably 30 to 50% by weight of the basic water-soluble component, 5 to 25%, preferably 10 to 15% by weight of oxygen-based bleach, 1 to 10% by weight, preferably 2 to 6% by weight of organic bleach activator, 0.1 to 5% by weight, preferably 0.5 to 2.5% by weight of enzyme, each time and an anticorrosive agent comprising, as the anticorrosive agent, an organic redox active selected from the group of diaminopyridines, aminohydroxypyridines, dihydroxypyridines, 15 heterocyclic hydrazones, aminohydroxypyrimimidines, dihydroxypyrimidines, triaminypyrimidines, tetraaminopyrimidines, tetraaminopyrimidines, tetraaminopyrimidines, tetraaminopyrimidines, tetraaminopyrimidines, tetraaminopyrimidines, , dihydroxynaphthalenes, naphthols, pyrrazoles, hydroxyquinolines, aminoquinolines, primary aromatic amines, which in the ortho position h-, meta- or para- have additional hydroxy or amino substituted by free or alkyl groups of 1 to 4 carbon atoms or hydroxyalkyl groups of 2 to 4 carbon atoms, or from di- or trihydrobenzenes. Composition according to claim 3, characterized in that the organic redox-active substance is selected from the group of p-hydroxyphenylglycine, 2,4-diaminophenol, 5-chloro-2,3-pyridinediol, 1- (p-aminophenyl) morpholine , hydroquinone, pyrocatechin, hydroxyhydroquinone, gallic acid, 25 floroglucin, pyrogallol. Composition according to claims 3 and 4, characterized in that it contains organic redox active substances in an amount of 0.05 to 5% 6% by weight of the total composition. A composition according to claim 5, characterized in that it contains organic redox actives in an amount of 0.2 to 2.5% by weight of the total composition. Composition according to claims 3 to 6, characterized in that the water-soluble component is a salt of citric acid, preferably sodium citrate. Composition according to claims 3 to 7, characterized in that the oxygen-based bleaching agent is a percarbonate salt, in particular sodium percarbonate. Composition according to claims 3 to 8, characterized in that the organic activator The bleach consists of Ν, Ν, Ν ', Ν'-tetraacetylethylenediamine. Composition according to claims 3 to 9, characterized in that the enzyme is amylase and / or protease. 45 Composition according to claims 3 to 10, characterized in that it contains up to 60% by weight of an alkali metal carrier consisting essentially of carbonate and bicarbonate, preferably sodium carbonate and sodium bicarbonate. Composition according to claim 11, characterized in that it contains 10 to 40% by weight of an alkali metal carrier consisting essentially of carbonate and bicarbonate, preferably sodium carbonate and sodium bicarbonate. Composition according to claims 3 to 12, characterized in that it contains up to 5% by weight, based on the total composition, of surfactants, preferably weakly foaming nonionics. 55 surfactants. -14GB 287850 B6 Composition according to claim 13, characterized in that it contains up to 2% by weight, based on the total composition, of surfactants, preferably weakly foaming nonionic surfactants. 5 Composition according to Claims 3 to 14, characterized in that it is in the form of tablets obtained by compressing the mixture of ingredients with a tablet press at pressures of 2 x 10 ⁷ Pa to 15 x 10 ⁸ Pa. Composition according to claims 3 to 14, characterized in that it is in the form of powder 10 or granules and has a bulk density of 750 g / l to 1000 g / l.