HU218008B - Silver-corrosion protection agents (i) and mashine cleaning agents containing thereof - Google Patents

Abstract

The invention concerns the use of organic redox compounds, in particular ascorbic acid, indole, methionine, N-(C1-C4 alkyl) glycines, 2-phenylglycine or coupler and/or development compounds selected from the group comprising diaminopyridines, aminohydroxypyridines, dihydroxypyridines, heterocyclic hydrazones, aminohydroxypyrimidines, dihydroxypyrimidines, tetraaminopyrimidines, triaminohydroxypyrimidines, diaminodihydroxypyrimidines, dihydroxynaphthalines, naphthols, pyrazolones, hydroxyquinolines, aminoquinolines, primary aromatic amines which have, in addition, a free hydroxy or amino group, or a hydroxy or amino group substituted with C1-C4 alkyl or C2-C4 hydroxyalkyl groups, at the ortho, meta or para position, and di- or trihydroxybenzenes as silver-corrosion protection agents in dishwasher washing agents, in particular low-alkali dishwaster washing agents.

Description

FIELD OF THE INVENTION The present invention relates to silver corrosion protection agents and to mechanical cleaning agents containing them.

It is a well-known fact that silver "runs" even when not in use. It is only a matter of time before you get dark, brownish, bluish, bluish-black spots, or completely discolor so that it "runs" according to normal language usage.

In practice, the "warming up" and discoloration of silver surfaces is also a problem when machine-cleaned tableware is machine cleaned. The silver may then react with sulfur-containing substances which are soluble or dispersible in the rinse water, as food residues, such as mustard, peas, eggs and other sulfur-containing compounds such as mercapto-amino acids, are ingested when cleaning dishes in household dishwashers. Higher temperatures during machine washing and longer contact time with sulfur-containing food residues also contribute to the silver "run-in" compared to hand washing. In addition, due to the intensive cleaning process in the dishwasher, the silver surface will be completely greasy and thus more sensitive to chemical influences.

In the use of active chlorine-containing cleaners, "run-in" by sulfur-containing compounds can be largely eliminated by converting these compounds into sulfones or sulfates by secondary reactions.

However, the problem of silver infiltration has become topical again when active oxygen compounds such as sodium perborate or sodium percarbonate have been used as an alternative to the active chlorine compounds, which are used to decolourize impurities such as tea stains / tea extracts, coffee residues and vegetable colorings.

These active oxygen compounds are used primarily in state-of-the-art low-alkali machine rinse aids of the next generation of detergents, together with bleach activators. These modem agents generally contain building blocks with the following function: "builder" components [complexing / dispersing agents], alkaline carriers, bleaching system (bleach + bleach activator), enzymes and wetting agents (surfactants).

Silver surfaces are significantly more sensitive to the new formulation parameters of the new generation of pH-reduced active chlorine-free detergents and active oxygen bleaches. During machine washing, these agents release the actual bleaching agent, i.e., hydrogen peroxide or active oxygen. The bleaching effect of the active oxygen detergent is enhanced by bleach activators so that good bleaching effect can be achieved at low temperatures. In the presence of these bleach activators, peracetic acid is formed as a reactive intermediate. Under these changed washing conditions, not only sulphide coatings, but also oxidative "coatings" are formed mainly on the silver surface due to the oxidative "attack" of the intermediate peroxides or active oxygen. In case of high salinity, additional chloride coatings may be formed. In addition, the silver hardness is enhanced by the higher hardness of the water during the washing process.

The prevention of silver corrosion, i.e., the formation of sulfide, oxide or chloride coatings on silver, is the subject of numerous publications. In these descriptions, the corrosion of silver is primarily prevented by so-called silver protective agents.

British Patent No. 1,131,738 discloses alkaline dishwashing detergents containing benzotriazoles as silver corrosion inhibitors. U.S. Pat. No. 3,549,539 discloses highly alkaline, machine-usable dishwashing detergents which may, among other things, contain perborate in combination with an organic bleach activator. Additives, including benzotriazole and ferric chloride, are also suggested as penetration inhibitors. A preferred pH range is 7 to 11.5. EP 135 226 and EP 135 227 disclose weakly alkaline, machine-usable dishwashing detergents containing peroxy compounds and activators which may contain, among others, benzotriazoles and fatty acids for the protection of silver. Finally, it is known from DE 41 28 672 that peroxy compounds, which are activated by the addition of known organic bleach activators, prevent the penetration of silver moieties in highly alkaline detergents.

Surprisingly, it has been found that salts or complexes of certain metals not previously described for protection against inorganic redox active substances, in particular silver corrosion, effectively inhibit silver corrosion in dishwasher detergents.

The present invention relates to the use of inorganic redox active substances as silver corrosion inhibitors in dish cleaning compositions.

The word "corrosion" is the broadest meaning of the term used in chemistry, which refers to a change in the surface of a metal, here silver, which is visually recognizable, whether it is a point-like discoloration or a large-area impact.

"Inorganic redox active substances" are inorganic substances which can undergo easily reversible oxidation and / or reduction. For example, oxides, hydroxides, or ammonium or alkali or alkaline earth metal halides are excluded from this definition.

As inorganic redox active substances there may be mentioned sulfur-based substances with different degrees of oxidation, such as Na ₂ S ₂ O ₃ (sodium (I) thiosulphate), Na ₂ S ₂ O ₄ (sodium (I) dithionite) or Na ₂ S ₂ O ₅ (sodium (I) disulphite).

However, salts or complexes of certain metals are particularly suitable. It is preferred to use salts and / or complexes of manganese, titanium, zirconium, hafnium, vanadium, cobalt, and cerium to prevent silver corrosion when the metals are present in the oxidation states II, III, IV, V or VI.

A common definition of "degree of oxidation" in chemistry is, for example, in the "Ripple Chemie Lexicon"

EN 218 008 (Georg Thieme, Stuttgart / New York, 9th edition 1991, p. 3168).

The metal salts or metal complexes used must be at least partially water-soluble. Salt-forming counterions include all the usual one, two or three negatively charged inorganic anions, such as stearate.

The metal complexes of the present invention are compounds consisting of a central atom and one or more ligands. The central atom is one of the abovementioned metals which is in the degree of oxidation specified above. Ligands are neutral molecules or anions that are single or multi-toothed; the term "ligand" in accordance with the spirit of the invention is illustrated, for example, by "Rump Chemie Lexikon" (Georg Thieme Publisher, Stuttgart / New York, 9th Edition, p. 2507). When the charge of the central atom in the metal complex and the charge of the ligand (s) are not added to zero, depending on whether it is a cationic or anionic excess, one or more of the above anions or one or more cations such as sodium, potassium, the ammonium ion will balance the charge. Examples of suitable complexing agents are citrate, acetylacetonate or 1-hydroxyethane-1,1-diphosphonate.

Particularly preferred metal salts and / or metal complexes are those which are MnSO ₄ , Mn (II) citrate, Mn (II) stearate, Mn (II) acetylacetonate, Mn (II) - [1-hydroxyethane-1]. , 1-diphosphonate], V ₂ O ₅ , V ₂ O ₄ , VO ₂ , TiOSO ₄ , K ₂ TiF ₆ , K ₂ ZrF ₆ , CoSO ₄ , Co (NO ₃ ) ₃ , and mixtures thereof. MnSO _{4 is} particularly preferred.

These metal salts or metal complexes are generally commercially available materials which can be used without prior purification for the silver corrosion protection of the present invention. For example, a mixture of pentavalent or quaternary vanadium (V ₂ O ₅ , VO ₂ , V ₂ O ₄ ) known from the SO _{3 preparation} (contact process) and titanium sulfate formed by diluting a Ti (SO ₄ ) ₂ solution are suitable. (TiOSO ₄ ).

Preferably, the inorganic redox active substances, in particular the metal salts or metal complexes, are completely coated, i.e. coated with a waterproof but readily soluble solvent at the purification temperature to prevent premature decomposition or oxidation upon storage. Preferred coatings which can be applied by the Sandwik melting coating known in the food industry are paraffins, microwaxes, natural waxes such as kamaubavia wax, candelilla wax, beeswax, high-reading alcohols such as hexadecanol, soaps or fats. According to the process, a solid coating material at room temperature is applied to the material to be coated in a molten state, for example, a continuous stream of the molten coating material is continuously "sprayed" on the molten coating material. The melting point should be selected such that the coating material will easily dissolve or melt rapidly in the dishwasher when subsequently used. Therefore, for most applications, the melting point is ideally in the range of 45 ° C to 65 ° C, preferably 50 ° C to 60 ° C.

The inorganic redox active substances described above are particularly useful for inhibiting silver corrosion when they are contained in low-alkaline detergents for machine cleaning of vessels. This is all the more surprising because the anti-corrosion agents of these silver corrosion agents are not diminished by the presence of oxygen-based bleaching agents which are usually present in low alkaline cleaning compositions.

Therefore, a further object of the present invention is to provide non-alkaline detergent compositions suitable for machine washing of dishes having a pH of 8 to 11.5, preferably 9 to 10.5, by weight; the solutions are 15-60% by weight, preferably 30-50% by weight, of water-soluble builder components, 5-25%, preferably 10-15% by weight of oxygen bleach, 1-10% by weight, preferably 2-6% by weight. % by weight of an organic bleach activator containing O or N- (C 1 -C 12) acyl groups, from 0.1 to 5% by weight of enzyme, preferably from 0.5 to 2.5% by weight (all components are based on the total agent) ) and contain a silver corrosion protection agent, whereas the silver corrosion protection agent is an inorganic redox active substance. Particularly suitable are metal salts and / or metal complexes of the manganese, titanium, zirconium, hafnium, vanadium, cobalt and cerium salts and / or complexes in which the metals have an oxidation degree of II, III, IV, V or VI.

The preferred dish detergents of MnSO _4, Mn (II) citrate, Mn (II) stearate, Mn (II) acetylacetonate, Mn (II), [I-hydroxyethane-l, l-diphosphonate], V ₂ Containing metal salts or metal complexes belonging to the groups O ₅ , V ₂ O ₄ , VO ₂ , TiOSO ₄ , K ₂ TiF ₆ , K ₂ ZrF ₆ , CoCO ₄ , CO (NO ₃ ) ₂ , Ce (NO ₃ ) ₃ blend. MnSO _{4 is} particularly preferred.

The total amount of inorganic redox active substances, in particular metal salts and / or metal complexes, in the agents according to the invention is 0.05 to 6% by weight, preferably 0.2 to 2.5% by weight, based on the total agent.

Organic bleach activators containing O or N- (C 1 -C 12) acyl groups are substances in which at least one C 1 -C 12 acyl group, preferably acetyl, is attached to the O or N atom present in the material, and their perhydrolysis yields C 1 -C 12 aliphatic peracids, preferably peracetic acid.

As a water-soluble component ("builder") for cleaning purposes, in principle, any "builder" used in dishwashing products is contemplated, for example, polymeric alkaline phosphates, which may be in the form of their alkaline, neutral or acidic sodium or potassium salts. Examples include tetrasodium diphosphate, disodium dihydrogen diphosphate, pentanedium triphosphate, so-called sodium hexametaphosphate, and the corresponding potassium salts, or sodium hexametaphosphate and the corresponding potassium salts and sodium and potassium salts. Phosphate

EN 218 008 Β approximately 30% by weight of the total mixture; however, the agents of the invention are preferably free of such phosphates. Other possible water-soluble "builder" components are, for example, organic polymers of native or synthetic origin, in particular polycarboxylates, which act as "co-builder" especially in hard water systems. For example, polyacrylic acids and copolymers of maleic anhydride and acrylic acid as well as sodium salts of these polymeric acids are contemplated. Common commercial products include Sokolan ^R CP 5 and PA 30 (BASF), Alcosperese ^R 175 or 177 (Alco), LMW ^R 45 N and SPO 2 N (Norsohaas). Native polymers include, for example, oxidized starches (e.g., patent application P 42 28 786.3) and polyamino acids, such as polyglutamic acid or polyaspartic acid (e.g., Cygnus or SRCHEM).

Other possible "builder" components are naturally occurring hydroxycarboxylic acids such as mono-, dihydroxybutyric acid, alpha-hydroxypropionic acid and gluconic acid. Preferred "builder" components are salts of citric acid, especially sodium citrate. Anhydrous trisodium citrate, and preferably trisodium citrate dihydrate is preferred as sodium citrate. Trisodium citrate dihydrate may be used as a fine or coarse crystalline powder. Depending on the adjusted pH of the agents of the present invention, citric acids may also be present.

Oxygen-based bleaching agents are primarily sodium perborate mono- and tetrahydrate or sodium percarbonate. The use of sodium percarbonate has the advantage of having a particularly favorable effect on the corrosion behavior of glass. Therefore, the oxygen-based bleaching agent is preferably a percarbonate salt, especially sodium percarbonate. Since the active oxygen does not produce its full effect at elevated temperatures, so-called bleach activators are added to the dishwasher to activate it. Bleach activators include bleach activators containing organic O- or N- (C 1 -C 12) acyl groups, such as PAG (pentaacetyl glucose), DADHT (1,5-diacetyl-2,4-dioxohexahydro-1,3). 5-triazine) and ISA (isatoic anhydride), but preferably Ν, Ν, Ν ', Ν'-tetraacetylethylenediamine (TAED). In addition, it may be desirable to use small amounts of known bleach stabilizers, such as phosphonates, borates, or metaphors and metasilicates, and magnesium salts such as magnesium sulfate.

To better dissolve protein, fat or starchy food residues, the dishwashing agent of the present invention also contains enzymes such as proteases, amylases, lipases and celluloses, such as: BLAP ^R 140 (Henkel); Optimase ^R -M440, Optimase ^R -M-330, Opticlean ^R -M-375, Opticlean ^R- M-250 (Solvay Enzymes); Maxacal ^R CX 450,000, Maxapem ^R (Ibis Company); Savinase ^R 4.0 T, 6.0 T, 8.0 T (Novo); Esperase ^R T (Ibis Company); and amylases such as Termamyl ^R 60 T, 90 T (Novo); Amylase-CT ^R (Solvay Enzymes) or Maxamyl ^R P 5000, CXT 5000 or CXT 2900 (Ibis); lipases such as Lipolase ^R 30 T (Novo); celluloses such as Celluzym ^R 0.7 T (Novo

Nordisk). The dish cleaners preferably contain proteases and / or amylases.

Preferably, the agents of the invention additionally contain alkali (carriers such as alkali-silicates, alkali-carbonates and / or alkaline-bicarbonates) commonly used in low-alkaline dishwashing detergents. Commonly-used alkali carriers include carbonates, in which the SiO ₂ / M ₂ O (M = alkali atom) is 1.5: 1 to 2.5: 1 The amount of alkali silicates may not exceed 30% by weight of the total agent Preferably, the alkali carrier is highly alkaline metasilicate. The alkali carrier system preferably used in the agents of the invention is a mixture of carbonate and bicarbonate, preferably sodium carbonate and bicarbonate, in an amount up to 60% by weight, preferably 10-40% by weight, based on the total agent. n pH is desired, and what pH is adjusted, the ratio of added carbonate to hydrogen carbonate varies; however, an excess of sodium bicarbonate is usually used, so that the weight ratio of bicarbonate to carbonate is generally 1: 1 to 15: 1.

Optionally, surfactants, in particular low-foaming nonionic surfactants, may be added to the agents of the present invention to improve the dissolution of fat-containing food residues and, as wetting agents, granulating aids or dispersants, lead to a better homogeneous . The amount of surfactants is then up to 5% by weight, preferably up to 2% by weight. Usually, highly foamed compounds are used. Preferably, these would include: (C12-C18) alkyl-polyethylene glycol-polypropylene glycol ethers having up to 8 moles of ethylene oxide and propylene oxide units. However, other nonionic surfactants known as foam-free surfactants, such as (C12-C18) alkyl-polyethylene glycol-polybutylene glycol ethers, containing up to 8 moles of ethylene oxide and butylene oxide units, and "terminated" alkyl- polyalkylene glycol mixed ethers, and effervescent but ecologically attractive (C 8 -C 14) alkyl polyglucosides having a degree of polymerization of about 1 to 4 (e.g., APG ^R 225 and APG ^R 600 (Henkel) and / or C 12-14) alkyl-polyethylene glycols having 3 to 8 ethylene oxide units in the molecule, preferably of yellowish color, otherwise they will form brown granules, and also surfactants of the glucamide family, such as alkyl N-methylglucamide (alkyl = C 6-14) Partially preferred is the use of the described surfactants as a mixture, for example, alkyl polyglycoside and fatty alcohol. ralkohol ethoxylates, or combinations glucamides and alkyl polyglycosides.

If the cleaning agents are too frothy in use, up to 6% by weight, preferably

From about 0.5% to about 4% by weight of antifoam compound, preferably silicone oils, silicone oils and hydrophobic silicas, paraffin oil / guerbetalcohol mixture, paraffins, hydrophobic silicas, bis (stearic acid amides) and other known foaming agents. Cleaner. Other additives, such as perfume oils, may optionally be used.

The dishwashing detergents of the present invention are preferably powder, granular or tablet formulations which can be prepared in a manner known per se, for example by mixing, granulating, cylindrical compacting and / or spray drying.

Detergent tablet according to the invention is preferably prepared by a mixing unit is mixed with all components with one another and the mixture is abnormal tablettapréseléssel, for example by means of an eccentric or rotary press 200 · 10 ⁵ Pa 150 010 ⁵ psi squeeze pressure to form tablets. In this way, tablets with a high breaking strength but dissolving at a satisfactory rate under the conditions used, generally having a flexural strength greater than 150 N, are obtained. The tablet thus prepared weighs 15-40 g, in particular 20-30 g, and has a diameter of 35-40 mm.

Typically, the non-dusting, storage-stable, sprayable powder and / or granulate machine dishwasher detergent in the high fill density range of 750-1000 g / l is typically prepared by blending the "builder" components in a liquid in a first step of the process. while increasing the filling density of at least a portion of the blend components, then, if desired after intermediate drying, further ingredients of the dishwashing detergent, including inorganic redox active agents, are combined with the resulting premix.

Since any alkali carbonate content strongly affects the alkalinity of the product, intermediate drying should be carried out in such a way that the decomposition of sodium bicarbonate to sodium carbonate is minimized (or at least possibly constant). The proportion of sodium carbonate that is formed by drying is to be taken into account when formulating the granular formulation. The low drying temperatures not only suppress the decomposition of sodium bicarbonate but also increase the solubility of the granular detergent when used. Therefore, it is preferable to use air which, when drying, has a temperature which is as low as possible to avoid decomposition of the bicarbonate and high enough to obtain a product having good storage properties. Preferably, the inlet air temperature during drying is about 80 ° C. The granulate itself should not be heated above about 60 ° C. In the first step of the mixing process, the "builder" component is usually "blended" with the liquid components by mixing with at least one other component of the detergent. An example of this is a preliminary step in which the "builder" components mixed with the perborate are "whipped" and / or thoroughly mixed with the liquid nonionic surfactants and / or the perfume solution. The remaining components are then added and the whole mixture is carefully blended and homogenized in the mixer. Simultaneous application of additional volumes of liquid, especially the addition of additional water, is generally not required. The resulting material mixture is then usually in the form of a flowable, non-dusting powder having a filling density of 750-1000 g / l.

The pre-granulate is then mixed with the remaining components of the detergent, including the redox active ingredients, to form the final product. In each of the cases described above, as well as the subsequent compression mixing and final mixing influenced by the liquid components, the mixing time is a few minutes, for example 1 to 5 minutes.

In a particular embodiment, when preparing fine grain cores, it may be desirable to provide further stabilization and equilibration by dusting the surface of the resulting grain core. Small amounts of water glass powder or powdered alkali carbonates are particularly suitable for this purpose.

The detergents to be used can be used in household and industrial dishwashers. Addition is done manually or with a suitable dispenser. The concentration used in the rinse bath is about 2-8 g / l, preferably 2-5 g / l.

The washing process is complemented and completed by rinsing with clean water and final rinsing with standard rinse aid. After drying, we obtain not only utensils that are perfectly clean and hygienically sound, but above all, bright sparkling cutlery.

Examples

Silver spoons (WMF type, hotel cutlery, Berlin form) are cleaned with silver cleaner, degreased with gasoline and dried. They are then placed in the cutlery basket of a Bosch S 712 household dishwasher. The cleaning program (65 ° C, 16 ° German hardness [dH]) is started and 50 g of dirt (1) and 30 g of cleaning agent are added directly to the machine. After the rinsing and drying process is complete, the dishwasher is opened for 10 minutes, then closed again and rinsed again in the same way. After rinsing run 10, the spoons are removed and evaluated. For this, the colors of the "run-in" are evaluated on a 0-4 point scale: 0 = no "run-in", 1 = full / slight yellow discoloration, 2 = more intense yellow discoloration, 3 = surface-wide golden-brown discoloration, 4 = violet-black discoloration; the values are shown in the upper left of Table 1.

1. Contaminant composition:

Ketchup 25g Mustard (extra strong) 25g roast sauce 25g potato starch 5g benzoic acid 1g yolk 3 pieces Milk 0.5 liters Margarine 92 g City water 608 ml

HU 218 008 Β

At the same time, we appreciate the removal of tea contamination from porcelain. Here the grading is on a scale of 0 to 10, where 0 = no removal and 10 = total removal of tea; the values are shown in the bottom right of Table 1. 5

Creating tea pollution

In a kettle, 16 liters of cold city water (16 ° dH) is rapidly heated to boiling. Leave the pan covered with 96 g of black tea in a nylon bag to stand and transfer the tea to a dipping apparatus with heating and stirring.

tea cup was immersed in brewed tea 25 times at 70 ° C for 1 minute. The cups are then hung and placed with their opening down on a tin plate for drying. 15

Detergent composition

First, the following, slightly alkaline basic product is prepared with a 1% w / w solution of distilled water to a pH of 9.5:

56.0% by weight trisodium citrate dihydrate

36.1% by weight of sodium bicarbonate

6.2% by weight of sodium carbonate, anhydrous 1.8% by weight of a nonionic surfactant mixture,

It consists of a 1: 1 by weight mixture of APG 225 (C8-C10 alkyl oligoglycoside) and Dehydol ^R LS 2 (C12-C14 fatty alcohol 2EO-ethoxylate).

With this masterbatch, the variants to be tested according to the following formula were executed. The results are shown in Table 1.

81-86% by weight base product% by weight sodium percarbonate 0-10% by weight TAED

0-2% by weight paraffin-coated manganese sulfate monohydrate% by protease 1% by weight amylase

Table 1

Tea Removal / Protection against Silver Corrosion

Machine: Bosch S 712

Dosage: 30g

Program: 65 ° C Universal

Water hardness: 16 ° dH

Tea: 1 = no cleaning

10 = optimum cleaning Silver: 0 = no penetration 4 = strong penetration

Further, dishwashing detergents were prepared with the following composition (see Table 2). The following compounds A-E were used as silver corrosion protection agents:

A: V ₂ O ₄ / V ₂ O ₅ 60

B: TiOSO ₄ C: COSO4 D: Ce (NO ₃ ) ₃ E: Na ₂ S ₂ O ₃ -5H ₂ O

HU 218 008 B

Table 2 (data by weight)

© 04 © CM 1 18.5 24 © © 1 co I 1 0.75 0.75 - - © 1 1 tt co 00 co © 1 Γ- CM - - wo ^ WO ^ · s, Q xi 10.5 00 r-- © CM 1 co 1 © 1 CM - - - - wo WO ^ © r ~ © ΓΜ l 18.5 ²⁴ © © 1 CO 1 0.75 0.75 - - © ^1/7 - Ο 1 1 T} - co 00 co © 1 r- CM - - WO wo ^ 3 10.5 WO oo © CM 1 CO tt 1 © 1 CM - - - - ω WO © 25.5 1 © WO CM © © 1 CO 1 1 0.75 0.75 - - Q co 1 I τί * co OO co © 1 r- CM - - WO WO u * 10.5 CM oo 30 1 co tf 1 © 1 CM - - - - ffl m WO ^ © - © CM 1 19.5 wo CM © © 1 co 1 1 0.75 0.75 - - <CO ₌ © 1 1 tt CO © co © 1 r- CM - - WO WO £? co V 10.5 © OO © CO 1 co TJ 1 © 1 CM - - - - Ω WO ^ © oo 26 1 © CM 25.5 © © 1 co 1 ¹ 0.75 0.75 - - U CM - She- 1 1 35 © co © 1 r- CM - - wo ^ WO ffl cl 10.5 © 00 © CO 1 44 1 © 1 CM - - - - < WO © " WO © CM 1 © CM 25.5 © © 1 CO 1 1 0.75 0.75 - - W ^Μ ' - TJ 1 1 wo CO © © 1 Γ- CM - - tendon g - 10.5 ro 00 co 1 tt You· 1 © 1 CM - - - g WO © CM r- CM 1 20 νγ WO * ' CM © © t CO 1 ¹ 1 0.75 ' 0.75 - - g _ E - 1 1 wo co 40 © 1 r- CM - - WO WO g- 10.5 Soda Na H carbonate Na-disilicate 2 E c -03 -i * . S5 sk- Η o Polycarboxylate (Sokolan CP5, BASF) Na Percarbonate Na perborate monohydrate TAED 1-1 _{C] 2} C _l4 -zsíralkoholetoxilát (Dehydol LS2, Henkel) SHE 0 < -I 12 o 22 K 5 «c • o 2 u 100 WO »- CM U Ο {N protease amylase Silver corrosion protection agent A-E PH of 10% aqueous solution

HU 218 008 Β

All the silver channels were rated 0-1 ("no or very poor run"). Therefore, formulations 1-20 provided excellent cleaning performance against bleachable impurities such as tea.

However, the same formulations, which did not contain A-D silver corrosion protection agents, although very effective against bleachable impurities, resulted in yellow-violet discoloration on silver spoons (rating 2-4).

Electrochemical measurements

Preparation of trial

Silver wire (diameter: 2 mm, 99%) was used as the test material instead of silver cutlery. Pieces of this silver were always cut off about 10 cm long and the portion of the probe to be immersed in the standard solution was polished with silica carbide sandpaper (grain 600). The samples were then rinsed thoroughly with double-distilled water and any adhering abrasive residue was wiped off with a non-fibrous cloth. This procedure was repeated several times, as appropriate, until the test produced an optically perfect impression. After grinding, probes were immediately measured to prevent the metallic silver from reacting with laboratory air. The probe immersed in the solution had an effective surface area of 0.70 cm ² .

Electrolytes and Electrodes

The experiments were performed in a rough glass cuvette. The silver electrodes (A = 0.70 cm ² ) were used as measuring electrodes. The counter electrode consisted of 1 cm ² gold plate (99.99%). As reference electrode, with respect to the alkaline electrolyte solution, a Hg / HgO / 0.1M NaOH electrode was contacted with the electrolyte solution through a Heber-Luggin capillary. Measurements were made with tap water (16 ° dH), 5 g / l of detergent solution, containing about 600 mg of salt (dry matter).

When using the detergent solution, the low alkaline stock (see above) was first dissolved and heated to 65 ° C. Immediately prior to measurement, bleach and bleach activator and / or silver corrosion protection agent were added. This was followed by electrochemical measurement. During the electrochemical experiments, the electrolyte solutions were kept at 65 ° C and rinsed with air.

Instrument and measurement curve

To record current-voltage curves, the electrode potential (relative to the standard hydrogen electrode) was increased at a constant rate starting from -0.62 V. After a total increase of 1.1 V, the potential was reduced at the same rate. It provided a standard potentiostat consisting of a feedback amplifier, a differential amplifier, an addition and an impedance converter, and a function generator (Prodis 16 from Intelligent Controls CLZ GmbH). Results

Corrosion was characterized using current-voltage curves. Relevant information was provided by the zero-transition of the current-voltage curves (a resting potential that automatically sets itself without any change in external potential) and the slope of the curve at the zero-transition (reciprocal polarization resistance) (Heitz, E., Henkhaus, R., Rahmel, A. "Verlag Chenie (1983), p. 31; Kaesche H.," Die Corrosion Dér Metalle ", 2nd edition, Springer Verlag (1979), p. Meanwhile, when the silver corrosion protection agent is added, the zero-transfer potential shifts to lower values and the slope of the curve decreases. Thus, the corrosion of silver is significantly reduced electrochemically by the addition of a corrosion inhibitor.

Detergent composition Nullaátmcnet place E (tnV) (ie H-electrode) Zero Transmission Slope di / dE (mA / V) Basic products (87%) 435 25 + 12% percarbonate + 1% TAED Basic products (87%) 360 0.3 + 12% percarbonate + 1% silver corrosion protection agent * Basic products (86.5%) 405 7 + 12% percarbonate + 1% TAED + 0.5% silver corrosion protection agent * Basic products (86%) 375 0.6 + 12% percarbonate + 1% TAED + 1% against silver corrosion protective agent *

* Silver corrosion protection agent: manganese sulfate monohydrate

Claims (15)

PATIENT INDIVIDUAL POINTS 1. The use of inorganic redox-active substances in dishwashing compositions as a protective agent against silver corrosion, characterized in that the inorganic redox-active substances are at least in part a group of private, titanium, zirconium, hafnium, vanadium, cobalt and cesium salts and / or complexes. water soluble metal salts and / or metal complexes, and the metals are in one of the oxidation stages II, III, IV, V or VI. Use according to claim 1, characterized in that the metal salts and / or metal complexes are MnSO ₄ , Mn (II) citrate, Mn (II) stearate, Mn (II) acetylacetonate, Mn (II). - [1-hydroxyethane-1,1-diphosphonate], V ₂ O ₅ , V ₂ O ₄ , VO ₂ , TiOSO ₄ , K ₂ TiF ₆ , K ₂ ZrF ₆ , CoSO ₄ , Co (NO ₃ ) ₂ and Ce (NO ₃ ) ₃ groups. Use according to claim 2, characterized in that the metal salt is MnSO ₄ . 4. Low alkaline agent for machine cleaning of containers with 1 to 8% by weight solution 8-11.5 At pH 9-10.5; 15-60 wt.%, preferably 30-50 wt.% water-soluble "builder" component, 5-25 wt.%, preferably 10-15 wt.% bleaching agent, 1-10 wt.%, preferably 2-6 wt.% organic, O- or N wt. - a bleach activator containing (1-12C) acyl groups, containing from 0.1 to 5% by weight, preferably from 0.5 to 2.5% by weight of enzyme, and a silver corrosion inhibitor, characterized in that the anti-corrosion agent is a , containing at least partially water-soluble metal salts and / or metal complexes belonging to the group of titanium, zirconium, hafnium, vanadium, cobalt, cerium salts and / or complexes, wherein the metals are the oxidation degree II, III, IV, V or VI; in one of them. 5. An agent according to claim 4, characterized in that the metal salts and / or metal complexes of MnSO _4, Mn (II) citrate, Mn (II) stearate, Mn (II) acetylacetonate, Mn (II) - [1-hydroxyethane-1,1-diphosphonate], V ₂ O ₅ , V ₂ O ₄ , VO ₂ , TiOSO ₄ , K ₂ TiF ₆ , K ₂ ZrF ₆ , CoSO ₄ , Co (NO ₃ ) ₂ and Ce (NO ₃ ) ₃ . The agent according to claim 5, wherein the metal salt is MnSO ₄ . 7. Refer to 4-6. An agent according to any one of claims 1 to 4, characterized in that the inorganic redoxactive substances are present in an amount of from 0.05 to 6% by weight, preferably from 0.2 to 2.5% by weight, based on the total agent. 8. Refer to 4-7. An agent according to any one of claims 1 to 3, characterized in that the water-soluble "builder" components are salts of citric acid, preferably sodium citrate. 9. An agent according to any one of claims 1 to 3, characterized in that the oxygen-based bleach is a percarbonate salt, preferably sodium percarbonate. 10. In FIGS. An agent according to any one of claims 1 to 3, characterized in that the bleach activator containing organic, O- or N- (C 1 -C 12) acyl groups is Ν, Ν, Ν ', Ν'-tetraacetyl ethylene diamine (TAED). 11. In FIGS. An agent according to any one of claims 1 to 4, wherein the enzyme is an amylase and / or a protease. 12. The 4 -11. An agent according to any one of claims 1 to 3, further comprising up to 60% by weight, preferably 10-40% by weight, of an alkali-carrying system based on the total agent, consisting essentially of carbonate and bicarbonate, preferably sodium carbonate and sodium bicarbonate. 13. Referring to FIGS. An agent according to any one of claims 1 to 4, further comprising up to 5% by weight of the surfactant, preferably not more than 2% by weight of the surfactant, preferably a weakly foaming nonionic surfactant. 14. Referring to FIGS. An agent according to any one of claims 1 to 4, characterized in that it is in the form of a tablet, which can be prepared by mixing all the components in a mixing apparatus and pressing the mixture in a tablet press device by pressing at a pressure of 2 · 10 ⁷ Pa-1.5-10 ⁸ Pa. 15. In FIGS. An agent according to any one of claims 1 to 3, characterized in that it is present in the form of a powder or granules and has a filling density of 750 g / l to 1000 g / l.