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|1. (WO2017202891) PROCESS FOR CORROSION-PROTECTING PHOSPHATIZATION OF A METALLIC SURFACE WITH REDUCED PICKLING EROSION|
|Inventors:||MOHR, Anna Verena
|Title:||PROCESS FOR CORROSION-PROTECTING PHOSPHATIZATION OF A METALLIC SURFACE WITH REDUCED PICKLING EROSION|
The present invention relates to a process for corrosion-protecting phosphatization of a metallic surface in which the surface is successively contacted with the following aqueous compositions: i) an alkaline or acidic cleaner composition, ii) a first washing composition, iii) optionally a second washing composition, iv) an acidic phosphatization composition, v) optionally a third washing composition and vi) a composition containing a (meth)acrylate- and/or epoxide-based KTL, wherein an activating agent is added to the cleaner composition i) and/or wherein between the contacting with the first washing composition ii) or optionally the second washing composition iii) and the phosphatization composition (iv) the metallic surface is contacted with an aqueous activating composition vii), wherein at least one of the compositions i) to v) contains at least one compound of formula (I) R1O-(CH2)x-Z-(CH2)y-OR2 and wherein R1 and R2 are each independently of one another H or an HO-(CH2)w group where w ≥ 2, x and y are each independently of one another 1 to 4, and Z is an S atom or a C-C triple bond, and to an aqueous composition for reducing pickling erosion in corrosion-protecting phosphatization of metallic surfaces.