Corrosion inhibitors for silver
AssigneeHenkel Kommanditgesellschaft auf Aktien
InventorsJuergen Haerer, Helmut Blum, Birgit Burg, Thomas Holderbaum, Willi Buchmeier, Peter Jeschke, Horst-Dieter Speckmann, Frank Wiechmann, Christian Nitsch
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Abstract
A process for inhibiting the corrosion of silver in a dishwashing detergent solution by adding to the solution an inorganic redox-active substance.
Claims18
The process of inhibiting the corrosion of silver in a dishwashing detergent solution obtained from a detergent composition containing 15 to 60% by weight of a water-soluble builder component, 5 to 25% by weight of an oxygen-based bleaching agent, 1 to 10% by weight of an organic bleach activator containing O- or N- (C.sub.1-12)-acyl groups, and 0.1 to 5% by weight of an enzyme, all weights being based on the weight of said detergent composition, comprising adding to said solution a silver corrosion inhibiting amount of an inorganic redox-active substance coated with a material solid at room temperature which is water-resistant but is readily soluble in water at a temperature of between 45.degree. C. and 65.degree. C., said inorganic redox-active substance comprising at least partly water-soluble metal salts or metal complexes selected from the group consisting of manganese, titanium, zirconium, hafnium, vanadium, cobalt and cerium salts and complexes and wherein the metals are present in one of the oxidation states II, III, IV, V or VI.
A low-alkali machine dishwashing detergent composition wherein a 1% by weight solution thereof has a pH value of 8 to 11.5, said composition containing 15 to 60% by weight of a water-soluble builder component, 5 to 25% by weight of an oxygen-based bleaching agent, 1 to 10% by weight of an organic bleach activator containing O- or N- (C.sub.1-12)-acyl groups, 0.1 to 5% by weight of an enzyme, based on the detergent as a whole, and a silver corrosion inhibiting amount of an inorganic redox-active substance coated with a material solid at room temperature which is water-resistant but is readily soluble in water at a temperature of between 45.degree. C. and 65.degree. C. said inorganic redox-active substance comprising at least partly water-soluble metal salts or metal complexes selected from the group consisting of manganese, titanium, zirconium, hafnium, vanadium, cobalt, and cerium salts and complexes, and wherein the metals are present in one of the oxidation states II, III, IV, V or VI.
Dependencies are inferred from the claim text.