Patent ID: 8864916

Claim:
An aqueous coating agent for producing a conversion layer on metal substrates, said coating agent being chromate-free and comprising: water; one or more complex fluorides of at least one element selected from Hf, B, Ti, Zr and Si; at least one ion selected from phosphate, manganate, vanadate, tungstate or molybdate ions from 0.01 to 40 wt. % of at least one low molecular weight oligomeric or monomeric compound which contains at least one H-active group that is an acidic group and at least one further functional group crosslinkable by radical polymerization, said oligomeric compound being selected from polyester or polyether oligomers having lateral or terminal (meth)acrylic groups, said monomeric compound being selected from esters or amides of low molecular weight carboxylic acids, or other monomers which contain activated double bonds; wherein pH of the aqueous coating agent is below 6; and wherein the low molecular weight compound is present in an amount of 0.5 to 25 wt. % and comprises from 0.1 to 15 wt. % of acidic derivatives of phosphoric acid or phosphoric acid with (meth)acrylates.