PASSIVATING ALKALINE COMPOSITION ON THE BASIS OF WATER GLASS

摘要

The present invention relates to an alkaline aqueous composition on the basis of water glass and organosilanes with non-hydrolysable substituents which have a primary amino group in the substituents, for providing corrosion-protected coatings on metal surfaces which convey good reshaping properties in metal processing. For the desired functionality, the compositions according to the invention contain the organosilane and the water glass in a predetermined ration. The invention further relates to a method for pre-treating metal surfaces using the alkaline aqueous compositions, which method provides excellent results with regard to corrosion protection, varnish adhesion and reshapability, particularly on aluminum and on steel strips provided with aluminum alloy metal coatings.

主权项

1. An alkaline water-based composition containing
a) water glass having a molar ratio of SiO2 to M2O of at least 3:2 but no more than 7:1, where M is selected from alkali metals and/or quaternary ammonium compounds; b) one or more organosilanes (A), each of which has at least one hydrolyzable substituent, which is split off in hydrolysis as an alcohol having a boiling point below 100° C. at an atmospheric pressure of 1 bar, and which have one to three non-hydrolyzable substituents on the respective silicon atom, these substituents having at least one primary amino group, wherein the total number of substituents on the respective silicon atoms of the organosilanes (A) is four,wherein the molar ratio of primary amino groups of the organosilanes (A) to the total amount of silicon atoms from water glass and organosilanes having at least one hydrolyzable substituent each amounts to at least 0.14 but no more than 0.3.