CONCENTRATE FOR USE IN CORROSION RESISTANT TREATMENT OF METAL SURFACES

摘要

The underlying invention consists in an acidic aqueous concentrate that is based on a mixture of water-soluble compounds of the elements Zr and/or Ti, organosilanes and dispersed silicates suitable for the preparation of a conversion treatment solution. The invention thereby establishes a shelf stable (1K) product useful for the surface treatment industry. Such a (1K) product has not only the advantage of being easily converted into a working composition through dilution with water, but the working compositions themselves that originate from the (1K) product do confer superior corrosion resistance to metal substrates when used in a process for the conversion coating treatment. A conversion treatment solution obtainable from the acidic aqueous concentrate as well as a process for the corrosion-resistant treatment of metal surfaces are thus further objects of this invention.

主权项

1. An acidic aqueous concentrate suitable for the preparation of a conversion-treatment solution comprising:
a. at least 0.1 wt.-%, calculated with respect to elements Zr and/or Ti, of one or more water-soluble compounds of the elements Zr and/or Ti; b. at least 0.05 wt.-%, calculated with respect to Si, of one or more organosilanes with at least one hydrolyzable substituent and one to three non-hydrolyzable substituents, wherein at least one of the non-hydrolyzable substituents carries at least one amino group, and wherein the total number of substituents at each silicon atom of the one or more organosilanes is four; and c. at least 0.1 wt.-%, calculated with respect to Si, of one or more water-dispersible silicates;wherein pH of the acidic aqueous concentrate is adjusted with nitric acid to a value below 1.5 and wherein other strong acids with a pKa value of below 1.5, different from water-soluble compounds of the elements Zr and/or Ti, are present in an amount of no greater than 0.05 wt.-%.