JPH08509778A - Silver corrosion protection agent (▲ II ▼) - 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

Detailed Description of the Invention                              Silver corrosion protector (II)   It is a well-known fact that silver "discolors" even when it is not in use. It Silver has dark, brownish, bluish or bluish stains, or It's a matter of time when it's completely faded, and thus in the normal sense of being "discolored". Only.   Practically, in the machine cleaning of silver tableware, it is repeated in the form of discoloration and fading of the silver surface. With the problems returned. In this case, silver contains sulfur dissolved or dispersed in the wash solution. Although it may react with substances, it does not produce food residues (DDWM) in household dishwashers (DDWM). (Including mustard, beans, eggs, and other sulfur-containing compounds) Because it is brought. Higher temperatures and higher sulfur content in dishwashers The relatively long contact time with food residues causes silver discoloration compared to washing dishes by hand. Facilitate. In addition, the thorough cleaning process in the dishwasher ensures that the silver surface is perfect. It is degreased and therefore more sensitive to chemical influences.   The use of detergents containing active chlorine greatly increases the discoloration caused by sulfur-containing compounds. Can hinder. This is because these compounds have sulfide functional groups in the secondary reaction. This is because it reacts with sulfones or sulfates by the oxidation of.   However, the problem of discoloration in the case of silver is that bleachable stains (e.g. brown stains). / To remove tea film, coffee residue, dye from vegetables, lipstick residue, etc.) Activate active oxygen compounds (for example, sodium perborate or sodium percarbonate). When used as a substitute for the chlorinated chlorine compound, it became a problem again.   These active oxygen compounds are especially useful in the latest new generation low-alkali mechanical dishwashing detergents. Used in combination with a bleach activator. Usually these latest detergents are Consists of functional components of: builder component (complexing agent / dispersant), alkali carrier, bleaching system ( Bleach + bleach activator), enzymes and wetting agents (surfactants).   Basically, the silver surface has an active chlorine content with a reduced pH value and activated oxygen bleaching. With a new generation of detergents with improved formulation parameters and higher sensitivity To respond. During the process of machine dishwashing, these detergents can actually bleach during the wash cycle. Releases agents, hydrogen peroxide or active oxygen. Bleaching action of detergent containing active oxygen Is enhanced by bleach activators, which results in good bleaching action even at low temperatures. Is obtained. In the presence of these bleach activators, peracetic acid acts as a reactive intermediate compound. Acid is produced. Under these improved cleaning conditions, a sulfide film forms in the presence of silver. Not only is it caused by the oxidizing action of the intermediately generated peroxide or active oxygen, An oxide film is also formed on the silver surface. Also, chloride film in the presence of high salt concentration Can also be formed. In addition, due to the relatively high residual water hardness value during the wash cycle, The silver discoloration is enhanced.   Avoiding silver corrosion, ie the formation of sulphide, oxide or chloride films on silver, is It is the subject of new publications. In these publications, the corrosion of silver is especially It is prevented by a silver protective agent.   GB 1,131,738 is an alkane containing benzotriazoles as a silver corrosion inhibitor. A potash dishwashing detergent is disclosed. US 3,549,539 oxidizes with organic bleach activators Open a highly alkaline machine dishwashing detergent that may contain perborate as an agent. Shows. Especially the addition of benzotriazole and iron (III) chloride prevents discoloration. Recommended for. A pH value of 7 to 11.5 is preferably mentioned. EP  135 226 and EP 135 227 are especially useful as silver protectants, especially for benzotriazole and A low alkali containing a peroxy compound and an activator, where fatty acids may be present. Re's machine dishwashing detergent is disclosed. Finally, the addition of known organic bleach activators Thus activated peroxy compounds prevent silver discoloration in highly alkaline detergents. It is known from DE-OS 41 28 672.   Surprisingly here are organic redox active substances, more specifically Oxidative dyes, which were not previously described as corrosion inhibitors for silver, The commonly used primary and / or secondary intermediates are effective in corroding silver in the dishwasher. We have found a rational prevention.   The present invention relates to an organic redox-active substance as a silver corrosion inhibitor in a dishwashing detergent. Regarding using quality.   The term "corrosion" should be construed in its broadest chemical sense. Than Specifically, the "corrosion" in the present invention means, for example, a morphology or a case of fading spots. For example, regardless of the shape of the stain that covers a relatively wide area, it should be on the metal surface (silver in this case). It is intended to mean any visually perceptible change.   An “organic redox-active substance” is an easily reversible oxidative and / or It is an organic substance that can utilize reduction. For example, conventional complexing agents such as E DTA or hydroxyethanediphosphonic acid and related compounds are defined by this definition. I can't get into it.   Common "organic redox-active substances" are, for example, ascorbic acid (vitamin C), indole, methionine (α-amino-γ-methylmercaptobutyric acid).   Also, N-mono- (C₁~ C_FourAlkyl) -glycine, for example N-monomethylglycine Syn, and N, N-di- (C₁~ C_FourAlkyl) -glycine, for example N, N-dimethyl Luglycine and 2-phenylglycine are also suitable.   In addition, certain primary and / or secondary intermediates known from oxidative dyes can be characterized. Suitable for   Organic substances which are preferably used for corrosion protection of silver include diaminopyridine, amino Hydroxypyridine, dihydroxypyridine, heterocyclic hydrazone, aminohydride Roxypyrimidine, dihydroxypysomidine, tetraaminopyrimidine, thoria Minohydroxypyrimidine, diaminodihydroxypyrimidine, dihydroxyna Phthalene, naphthol, pyrazolone, hydroxyquinoline, aminoquinoline, o Another free or C at the lut, meta or para position₁~ C_FourAlkyl or C₂~ C_FourHi First aromatic amine having a hydroxy or amino group substituted by droxyalkyl Primary and di- or tri-hydroxybenzene selected from the group consisting of And / or a secondary intermediate.   The primary and secondary intermediates used according to the invention to prevent silver corrosion are: Substances from the above mentioned group which are commonly used in oxidative dyes. Such a primary And examples of secondary intermediates are, for example, Venkataraman, “Synthetic dye Chemistry, Volume V, Academic Press, New York / Ron Don, 1971, pp. 478-495 and references cited therein. . p-Hydroxyphenylglycine, 2,4-diaminophenol, 5-chloro- 2,3-pyridinediol, 1- (p-aminophenyl) -morpholine, hydroquino , Pyrocatechol, hydroxyhydroquinone, gallic acid, phloroglucinol , The primary and secondary intermediates selected from the group consisting of pyrogallol prevent silver corrosion Especially suitable for.   Organic redox-active substances prevent premature decomposition or oxidation during storage Coated, ie water resistant, but readily soluble at dishwashing temperature It is preferably completely surrounded by the material. By known methods, for example, food industry Applied by Sandwik melt coating method used in industry Preferred coating materials are paraffins, microwaxes, naturally occurring waxes, eg For example, carnauba wax, candelilla wax, beeswax, alco with a relatively high melting point. , Eg hexadecanol, eg soaps or fatty acids. Solid at room temperature The coating material is applied to the material to be coated in molten form. For example, the fine particles to be coated Injecting a child material in a continuous flow into a continuously producing spray atomization zone of molten coating material Applied by. This melting point is not used during subsequent use in a dishwasher with a silver corrosion inhibitor. The covering material must be chosen to dissolve easily or to melt quickly. Yes. Therefore, for most applications, the melting point should ideally be 45-65 ° C. It is preferable that it is 50-60 degreeC.   However, the above-mentioned organic redox-active substances, especially in low alkaline machine dishwashing Suitable for preventing silver corrosion when used in detergents. This is , These silver corrosion inhibitors are of the oxygen-based bleaching agents normally present in low-alkali detergents. More surprising as presence is unaffected in their effects It should be done.   Accordingly, the present invention is a low alkaline machine dishwashing detergent, the 1 wt% solution of which is It has a pH value of 8 to 11.5, preferably 9 to 10.5 and is 15 based on the total detergent. -60% by weight, preferably 30-50% by weight of water-soluble builder component, 5-25% by weight % Oxygen bleach, preferably 10-15% by weight, preferably 1-10% by weight. Preferably 2 to 6% by weight of organic bleach activator, 0.1 to 5% by weight, preferably 0.5. ~ 2.5% by weight of enzyme, and silver corrosion inhibitor (organic redox-active substances are (Present as an inhibitor). A particularly suitable silver corrosion inhibitor is , Ascorbic acid, indole, methionine, N, N'-di- (C₁~ C_FourAlkyl) -Glycine and 2-phenylglycine, but especially diaminopyridine , Aminohydroxypyridine, dihydroxypyridine, heterocyclic hydrazone, a Minohydroxypyrimidine, dihydroxypyrimidine, tetraaminopyrimidine , Triaminohydroxypyrimidine, diaminodihydroxypyrimidine, dihydride Roxynaphthalene, naphthol, pyrazolone, hydroxyquinoline, aminoquino Another free or C in the phosphorus, ortho, meta or para position₁~ C_FourAlkyl or C₂ ~ C_FourNo. 1 having hydroxyalkyl-substituted hydroxy or amino group 1 selected from the group consisting of aromatic amines and di- or trihydroxybenzenes It is a secondary and / or secondary intermediate.   The preferred dishwashing detergent is p-hydroxyphenylglycine, 2,4-diaminophen. Enol, 5-chloro-2,3-pyridinediol, 1- (p-aminophenyl)- Morpholine, hydroquinone, pyrocatechol, hydroxyhydroquinone, gallic Selected from the group consisting of acids, phloroglucinol, pyrogallol and mixtures thereof. It contains the primary and / or secondary intermediates that are categorized.   The organic redox-active substance is preferably 0.05-5% by weight, based on the total detergent, More preferably, it is present in the detergent of the present invention in a total amount of 0.2 to 2.5% by weight. Good   Basically, a suitable water-soluble builder ingredient is an alkaline, neutral or acidic sodium Usually in mechanical dishwashing detergents, which may be present in the form of the potassium or potassium salts Is any builder used (eg polymeric alkali metal phosphates) . Examples include tetrasodium diphosphate, disodium dihydrogen diphosphate, triphosphate. Pentasodium, so-called sodium hexametaphosphate and the corresponding potassium salt Or a mixture of sodium hexametaphosphate and the corresponding potassium salt or sodium To Included is a mixture of the potassium and potassium salts. The amount of phosphate is based on the total detergent. Up to about 30% by weight. However, the detergents of the present invention do not contain such phosphates. It is preferable not to have it. Other possible water-soluble builder ingredients are, for example, especially hard water. Organic polymers of natural or synthetic origin which can act as co-builders in the system, especially It is a polycarboxylate. For example, with polyacrylic acid and maleic anhydride It is possible to use copolymers of acrylic acid and the sodium salts of these polymeric acids. it can. Commercial products include, for example, Sokalan.^R) CP5 and PA30 [Ba Zuff (BASF)], Alcosperse (Alcosperse^R) 175 or 177 [Alco )], Elm W (LMW^R) 45N and SPO2N [Norso Haas (No rsohaas)]. Natural polymers include, for example, oxidized starch (eg, Germany Patent application P 42 28 786.3) and polyamino acids such as polyglutamic acid or Riaspartic acid [eg Cygnus or SRCHEM] Product] is included.   Other possible builder components are natural hydroxycarboxylic acids, such as monohydro Xysuccinic acid, dihydroxysuccinic acid, α-hydroxypropionic acid and glucose Examples include conic acid. A preferred builder component is a salt of citric acid, more specifically It is sodium enoate. The sodium citrate used is anhydrous trisodium citrate. It may be llium, but dihydrated trisodium citrate is preferred. Dihydrate Trisodium enoate may be used in the form of a fine or coarse crystalline powder. Also, The acid corresponding to citrate depends on the pH value finally determined in light detergent. May exist.   Suitable oxygen-based bleaches include sodium perborate monohydrate and tetrahydrate, among others. It is a Japanese product or sodium percarbonate. The use of sodium percarbonate is Advantageously, um has a particularly favorable effect on the corrosion behavior of glass. Follow Thus, the oxygen-based bleach is preferably a percarbonate, more specifically a sodium percarbonate. Umm. Active oxygen only shows its full effect at high temperatures, so Iwayu Activate it in the dishwasher with the bleach activator. Proper bleach activation Agents are organic bleach activators such as PAG (pentaacetyl glucose), DADH T (1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine) And ISA (isatoic anhydride), N, N, N ', N'-tetraacetylethylene Diamine (TAED) is preferred. In addition, small amounts of known bleach stabilizers, such as Phosphonate, borate or metaborate and metasilicate and magnesi It may be useful to add um salts, for example magnesium sulfate.   To improve removal of food residues containing protein, fat or starch The dishwashing detergent of the present invention contains enzymes such as proteases, amylases and lipases. ZE and cellulases. These are, for example, BLAP^R140 [F Henkel]; Optimase^R) -M-440, Optimase-M -330, Opticlean^R) -M-375, Opticlean-M-2 50 [Solvay Enzymes]; Maxacal^R) CX 450.000, Maxapem^R) [Ibis]; Savinase se^R) 4.0T, 6.0T, 8.0T [Novo]; Esperase^R) T [ Ibis] and other proteases and Termamyl^R) 60T, 90T [Novo]; Amylase-LT^R[Solvay Enzymes] or Max Samil (Ma xamyl^R) P5000, CXT5000 or CXT2900 [Ibis] Amylases; Lipolase^R) Lipases such as 30T [Novo]; cells Zym (Celluzym^R) Cellular such as 0.7T [Novo Nordisk] It is a kind. Dishwashing detergent contains proteases and / or amylases. It is preferable to have.   In a preferred embodiment, the detergent of the present invention is a conventional low alkali machine dishwashing detergent. Existing alkali carriers such as alkali metal silicates, alkali metal carbonates and And / or alkali metal hydrogen carbonate. Commonly used alkali Carriers include carbonates, hydrogen carbonates and alkali metal silicates [SiO 2₂And M₂O (M = Alkali metal atom) molar ratio of 1.5: 1 to 2.5: 1] is included. alkali The metal silicate may be present in an amount of up to 30% by weight, based on the total detergent. Highly alkaline metasilicate is preferably not used as an alkali carrier . The preferred alkaline carrier system for use in the detergents of the present invention is substantially Present in an amount of up to 60% by weight, preferably 10-40% by weight, based on the total detergent Ru Carbonate and bicarbonate, preferably a mixture of sodium carbonate and sodium bicarbonate Is. The ratio of carbonate used to bicarbonate used is ultimately required or established. It changes according to the pH value. However, usually use excess sodium bicarbonate Therefore, the weight ratio of bicarbonate to carbonate is usually 1: 1 to 15: 1. It   If desired, a surfactant, more specifically a low-foaming nonionic surfactant, may be added. It can be added to the inventive detergents to improve the removal of fat-containing food residues. Also, They act as wetting agents, granulating aids or dispersing aids, in the wash liquor and in the silver. Improve and homogenize the distribution of silver corrosion inhibitors on the surface. This surfactant is 5 It is used in an amount of up to 2% by weight, preferably up to 2% by weight. Extremely low foaming It is customary to use compounds, which preferably contain up to 8 moles of ethyl in the molecule. C with lenoxide and propylene oxide units₁₂~ C₁₈Alkyl polyethylene Glycol glycol polypropylene glycol ether. But low foaming agent Other nonionic surfactants known as can also be used. This includes, for example , C containing up to 8 moles of ethylene oxide and butylene oxide units in the molecule₁₂ ~ C₁₈Alkyl polyethylene glycol polybutylene glycol ether, powder End-capped alkyl polyalkylene glycol mixed ether and foaming C with a degree of polymerization of about 1 to 4 which is environmentally attractive₈~ C₁₄Alkyl poly Glucoside (eg APG^R225 and APG^R600, Henkel) and / Or C containing 3 to 8 ethylene oxide units in the molecule₁₂~ C₁₄Alkylpo Includes polyethylene glycol. You should use bleached quality This is because brown granules are produced without it. Also, glucami Group such as alkyl-N-methylglucamide (alkyl = C₆~ C₁₄Fat alco Surfactants) are also suitable. In some cases, the surfactants described above Is preferably used in the form of a mixture. For example, alkyl polyglycoside and fat Mixture of fatty alcohol ethoxylates or glucamide and alkyl polyglycosyl It is advantageous to use a mixture of the like.   If the detergent foams excessively during use, preferably use silicone oil or silicone. Mixture of oil and hydrophobized silica, paraffin oil / Guerbet Arco , Paraffin, hydrophobized silica, bis-stearic acid amide and other known Up to 6% by weight of foam control compounds from the group consisting of commercially available defoamers May be added to the detergent in an amount of, preferably about 0.5-4% by weight. Elsewhere Optional additives are, for example, aromatic oils.   The dishwashing detergent of the present invention is preferably present as a powder, granules or tablets. They can be prepared by known methods, for example by mixing, granulating, roll compacting and And / or spray drying.   In order to produce the detergent of the invention in tablet form, preferably all formulations are The ingredients are mixed together in a mixer and the resulting mixture is processed on a conventional tablet press. , For example in an eccentric or rotary press 200.10.^Five~ 1500/10^FivePa Tablet under the pressure of. It usually has a bending strength of over 150N, so A crush resistant tablet that dissolves well and quickly under the conditions of use And easily obtained. Correspondingly manufactured tablets have diameters of 35-40 mm On the other hand, it weighs 15 to 40 g, more specifically 20 to 30 g.   Has a high apparent density of 750-1000 g / L and can be stored without dust emission The production of machine dishwashing detergents in the form of free flowing powders and / or granules is In the first step, mix the builder ingredients with at least some liquid ingredients A mechanical dish that increases the apparent density of couscous and then contains organic redox-active substances Other ingredients of the laundry detergent are mixed with the obtained premix, optionally after drying. It is characterized by the following.   The possible presence of alkali metal carbonates has a significant effect on the alkalinity of the product. Since the intermediate drying step is sodium bicarbonate Must be done in such a way that minimal (or at least constant) decomposition into No. Any additional sodium carbonate produced as a result of drying will, of course, It will have to be taken into account in the formulation for the granules. Carbonated at low drying temperatures Not only prevents the decomposition of sodium hydrogen, but also increases the solubility of the granulated detergent during use Let Therefore, the drying should, on the one hand, be as low as possible to avoid hydrogencarbonate decomposition. And on the other hand, at the height required to obtain a product with good storage properties. It is expedient to carry out at different incoming air temperatures. Inflow air temperature of about 80 ° C is due to drying Preferred. The granules themselves should not be heated to temperatures above about 60 ° C. Mixed Apply the liquid ingredients to the builder in the first step of the combining process (usually the builder Applied after mixing with at least one other ingredient of the dishwashing detergent). For example, Mixture of liquid nonionic surfactant and / or fragrance solution with perborate May be applied to the builder ingredient in the form of and mixed well therewith. Then the rest Ingredients are added and the entire mixture is blended in a mixer to homogenize. Usually an additional amount It does not require the use of any liquid, i.e. additional water. The resulting mixture is free flowing It is present in the form of a dust-free, dynamic powder, with the required high of about 750-1000 g / L. It has an apparent density.   The granules are then passed through the missing ingredients of the dishwashing detergent (organic redox-active substances). To obtain the final product. In all cases described here, liquid Preliminary stage of condensing and mixing in the presence of ingredients and the next final to introduce other ingredients The mixing time in both of the mixing stages is a few minutes, for example 1 to 5 minutes.   In one particular embodiment, the surface of the resulting granules is sprinkled with powder. To further stabilize and ensure homogenization, it is necessary to manufacture high-quality granules. Sometimes it can be useful. A small amount of water glass powder or alkaline gold in powder form Genus carbonates are particularly suitable for this purpose.   The detergent used should be used in both domestic and commercial dishwashers. Can be Add these detergents by hand or using a suitable dispenser. Add Concentration when used in dishwashing liquid is about 2-8 g / L, preferably 2-5 g / L Is.   The dishwashing program consists of several intermediate rinses with clean water after the main wash cycle. Therefore, and by the last wash cycle with a commercial rinse aid, And is usually terminated. Completely clean and hygienically satisfying crockery Not only that, but especially brilliant silver dishes are obtained after drying.                                 Example   Clean silver spoon (WMF type, tableware for hotel, Berlin style) with silver detergent Defatted with naphtha and dried. Then add 3 spoons to Bosch It was placed in the dish basket of an S712 type domestic dishwasher (DDWM). Then wash pro Start the gram (65 ° C, 16 ° dH) and put the following washes on the dishwasher during the main wash cycle. (50 g) and detergent (30 g) were introduced directly. After rinsing and drying, add 1 DDWM Open for 0 minutes, then close again and operate in the same way. 10 wash cycles After that, the spoon was taken out and evaluated. Discoloration was rated on the following scale of 0-4:       0 = no discoloration;       1 = very slight yellowing;       2 = strong yellowing;       3 = Completely golden to brown discoloration;       4 = Change to purple or black. This value is shown on the upper left side of Tables 1 to 3.     Stain composition       Ketchup: 25g       Mustard (Special #): 25g       Gravy: 25g       Potato starch: 5g       Benzoic acid: 1g       Egg yolk: 3 eggs       Milk: 1 / 2L       Margarine: 92g       Local water: 608 ml   At the same time, we also evaluated the removal of stains on the tea of Seto. Rating is 0-10 grade Based on 0 indicates that the tea stains were not removed at all, and 10 indicates that the tea stains were completely removed. This is the case when they are completely removed. This value is shown on the lower right side of Tables 1 to 3.   Preparation of tea stains   16 L of cold local water (16 ° dH) are briefly heated in the tank to the boiling point. 9 Extract 6 g of black tea in a covered nylon mesh for 5 minutes, then Transfer to a dipping device equipped with heating system and stirrer. In the black tea prepared in this way, Sixty tea cups were soaked 25 times at a temperature of 70 ° C. at 1 minute intervals. Then Take out this cup, place it on a metal plate, and open the cup surface downward. dry.   Detergent composition   The following low-alkali basic products were first prepared (distilled water with a pH value of 9.5): 1% by weight solution in):   56.0% trisodium citrate dihydrate   36.1% sodium hydrogen carbonate     6.1% anhydrous sodium carbonate     1.8% nonionic surfactant APG225 (C₈~ C_TenAlkyl oligo              Glucoside) and Dehydol^R) LS2 (C₁₂~ C₁₄              Mixture of fatty alcohol and 2EO ethoxylate (1: 1)   This basic product was then used to carry out pilot variations corresponding to the following formulations . The results are shown in Tables 1 to 3.   81-86% by weight Basic product   12% by weight sodium percarbonate     0-10% by weight TAED     0-3% by weight pyrocatechol, gallic acid or hydroquinone     1% by weight protease     1% by weight amylase   In addition, a machine dishwashing detergent having the following composition was prepared (see Table 4). below Compounds AM were used as silver corrosion inhibitors;       A: p-hydroxyphenylglycine;       B: 2,4-diaminophenol;       C; 5-chloro-2,3-pyridinediol;       D: 1- (p-aminophenyl) -morpholine;       E: Ascorbic acid;       F: monomethylglycine;       G: N, N-dimethylglycine;       H: 2-hydroxy-4-aminopyrimidine;       I: 2,4-dihydroxy-5-methylpyrimidine;       K: Indole;       L: methionine;       M: 2-phenylglycine.   All silver spoons were given a score of 0-1. That is, "if at all, the pole Very slight discoloration "was evaluated. The same composition containing no silver corrosion inhibitors A to D is The color of the silver spoon was changed from yellow to purple (score: 2 to 4).Electrochemical measurement   Sample preparation   Instead of silver tableware, silver wire (D = 2mm, 99.99%) is used as a test sample material. Using. Cut this silver wire to a length of about 10 cm and immerse the part of the sample immersed in the measurement solution. Rubbed with SiC polishing paper (600 grains). This sample was then subjected to double distilled water Rinse thoroughly and wipe off any polishing residue adhering to the sample with a lint-free cloth It was If desired, repeat this procedure several times until the sample gives a visually pleasing impression. I repeated. After rubbing with abrasive paper, the sample was immediately used for measurement and used with metallic silver and empty laboratory. Prevented all reactions with Qi. The effective surface area of the sample immersed in the solution is 0.70 cm²Met.   Electrolytes and electrodes   The experiments were carried out in a Duran glass cell. Above silver wire (A = 0.70cm² ) Was used as the measurement electrode. Counter electrode has a surface area of 1 cm²From gold leaf (99.99%) It was In view of the alkaline electrolyte solution, the reference electrode is Haber-Luggin (Ha A Hg / HgO / 0.1M NaOH electrode connected to the electrolyte with a ber-Luggin) capillary. The measurement is about 600 mg (dry residue) salt concentration and 5 g in tap water with a hardness of 16 ° dH. / L detergent was used.   To prepare the detergent solution, first dissolve the low alkali base product (see above). The resulting solution was heated to 65 ° C. Bleach and bleach activator and / or A silver corrosion inhibitor was added immediately before the measurement. Then, an electrochemical measurement was performed. Electric The electrolyte solution was maintained at 65 ° C. and purged with air during the gas chemistry experiments.   Instrument and measurement curve recording   Electrode potential based on a standard hydrogen electrode (SHE) for recording current / voltage curves Was increased at a constant rate from -0.62V. After a total increase of 1.1V Reduced at the same rate. Regenerative amplifier, differential amplifier, adder and impedance A conventional potentiostat consisting of a transformer and a function generator [Intelligent ・ Pro-dis (Pr) of Controls CLZ GmbH (Intelligent Controls CLZ GmbH) odis) 16] was used for this purpose.   result   The corrosion behavior was characterized based on the current / voltage curve. Important information is current / electricity Zero-axis crossing of the pressure curve (naturally without any external influence of the potential (Resting potential applied) and the slope of the curve at zero crossing (reverse polarization resistance). [Heights (E.Heitz), Henk House (R.Henkhans), Ramel (A.Rahmel), "Experimental Corrosion", Verlag Chemie, 1983, p. 31 et seq .; H. Kaesche, "Corrosion of Metals", Second Edition, Springer Feller K. Chemie (Springer Verlag Chemie, p. 117 et seq.). Addition of silver corrosion inhibitor, It provides a shift of the zero-axis crossing potential to lower values and a decrease in slope. That is, electricity Chemical measurements also show that the addition of silver corrosion inhibitors significantly reduces silver corrosion. You

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI C11D 17/06 9546-4H C11D 17/06 (81) Designated country EP (AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), CA, CZ, HU, JP, PL, US (72) Inventor Burg, Birgit Germany Federal Republic of Germany Day 46519 Arpen, Dolph Straace 88 (72) Inventor Holder Baum, Thomas Germany Day-40789 Mornheim, Helene-Wessel-Week 3 (72) Inventor Buchmeier, Villi Germany Day-40822 Mettmann , Ost-Prussian Strasse 49 (72) inventor Jäschke, Germany Germany Day 41468 Neuss, Maher Scheider Strasse 137 (72) Inventor Speckmann, Horst-Dieter Germany Day 40764 Langenfeld, Eichenfeld Strasse 24 (72) Inventor Wichmann, Frank Federal Republic of Germany Day-40229 Düsseldorf, Gümbertstraße 186 (72) Inventor Nietzsche, Christian German Republic of Germany Day-40591 Düsseldorf, Otto-Hahn-Straasse 185

Claims (1)

[Claims]   1. Of organic redox-active substances as corrosion inhibitors for silver in dishwashing detergents use.   2. Organic redox-active substances are ascorbic acid, indole or methionine. Use according to claim 1, characterized in that it is nin.   3. Organic redox-active substances are N-mono- (C₁~ C_FourAlkyl) -glycine, N, N-di- (C₁~ C_FourAlkyl) -glycine or 2-phenylglycine Use according to claim 2, characterized in that   4. Organic redox-active substances include diaminopyridine and aminohydroxypyridine. Gin, dihydroxypyridine, heterocyclic hydrazone, aminohydroxypyrimidi , Dihydroxypyrimidine, tetraaminopyrimidine, triaminohydroxy Pyrimidine, diaminodihydroxypyrimidine, dihydroxynaphthalene, naphth Thor, pyrazolone, hydroxyquinoline, aminoquinoline, ortho, meta or Is another free or C at the para position₁~ C_FourAlkyl or C₂~ C_FourHydroxy alk Primary aromatic amines with di-substituted hydroxy or amino groups and di In the primary and / or secondary selected from the group consisting of trihydroxybenzene Use according to claim 1, characterized in that it is an intermediate body.   5. The primary or secondary intermediate is p-hydroxyphenylglycine, 2,4-dia Minophenol, 5-chloro-2,3-pyridinediol, 1- (p-aminophenyl ) -Morpholine, hydroquinone, pyrocatechol, hydroxyhydroquinone, Specially selected from the group consisting of gallic acid, phloroglucinol, and pyrogallol Use according to claim 4, which is an indicator.   6. A low alkaline machine dishwashing detergent whose 1% by weight solution is 8 to 11.5 , Preferably having a pH value of 9 to 10.5 and 15 to 60% by weight, based on the total detergent , Preferably 30 to 50% by weight of water-soluble builder component, 5 to 25% by weight, preferred Or 10 to 15% by weight oxygen-based bleach, 1 to 10% by weight, preferably 2 to 6 Wt% organic bleach activator, 0.1-5 wt%, preferably 0.5-2.5 wt% Organic redox-active substances containing various enzymes and silver corrosion inhibitors A detergent characterized by being present as an antidote.   7. Ascorbic acid, indole or methionine exist as silver corrosion inhibitors 7. The detergent according to claim 6, which is present.   8. N-mono- (C₁~ C_FourAlkyl) -glycine, N, N-di- (C₁~ C_FourAlkyl)- Glycine or 2-phenylglycine are present as silver corrosion inhibitors. The detergent according to claim 6, which is a characteristic.   9. Diaminopyridine, aminohydroxypyridine, dihydroxypyridine, Heterocyclic hydrazone, aminohydroxypyrimidine, dihydroxypyrimidine, Tetraaminopyrimidine, triaminohydroxypyrimidine, diaminodihydro Xypyrimidine, dihydroxynaphthalene, naphthol, pyrazolone, hydroxy Siquinoline, aminoquinoline, ortho, another free or C at the meta or para position₁ ~ C_FourAlkyl or C₂~ C_FourHydroxyalkyl substituted hydroxy also Is a primary aromatic amine having an amino group and di- or trihydroxybenzene A primary and / or secondary intermediate selected from the group consisting of 7. The detergent according to claim 6, which is present.   10. The primary or secondary intermediate is p-hydroxyphenylglycine, 2,4-dia Minophenol, 5-chloro-2,3-pyridinediol, 1- (p-aminophenyl ) -Morpholine, hydroquinone, pyrocatechol, hydroxyhydroquinone, Specially selected from the group consisting of gallic acid, phloroglucinol, and pyrogallol The detergent according to claim 9, which is used as a characteristic.   11. Organic redox-active substances, 0.05 to 6% by weight, based on the total detergent Is present, preferably in an amount of 0.2-2.5% by weight. The detergent according to any one of claims 6 to 10.   12. The water-soluble builder component is a salt of citric acid, preferably sodium citrate. The detergent according to any one of claims 6 to 11, which is present.   13. The oxygen-based bleach is a percarbonate, preferably sodium percarbonate. The detergent according to any one of claims 6 to 12, wherein:   14. The organic bleach activator is N, N, N ', N'-tetraacetylethylenediamine ( Detergent according to any of claims 6 to 13, characterized in that it is TAED).   15． Contract characterized in that the enzyme is amylase and / or protease The detergent according to any one of claims 6 to 14.   16. Up to 60% by weight, preferably 10-40% by weight, of the total detergent, Qualitatively, carbonate and hydrogen carbonate, preferably sodium carbonate and sodium hydrogen carbonate. Any of claims 6 to 15 further comprising an alkaline carrier system consisting of The detergent described in Crab.   17． Surfactant up to 5% by weight, preferably up to 2% by weight, based on the total detergent , Preferably further containing a low foaming nonionic surfactant The detergent according to any one of claims 6 to 16.   18. Present in the form of a tablet, mix all ingredients in a mixer and obtain the resulting mixture 2.10.⁷~ 1.5 / 10⁸Tablelet under pressure of Pa 18. The method according to claim 6, which is obtained by converting to Detergent.   19. It exists in the form of powder or granules and has an apparent density of 750 to 1000 g / L. The detergent according to any one of claims 6 to 17, which comprises: