Patent ID: 8906990

Claim:
A surface treatment agent for galvanized steel sheets, which comprises the following components: A. an epoxy-containing silane derivate having a structure as shown in formula I wherein, Y is a C 1 -C 6 alkylene, R is a C 1 -C 6 alkyl, X is a C 1 -C 4 alkoxy or C 2 -C 4 acyloxy, and n=0 or 1; B. an alkyl-containing silane derivative having a structure as shown in formula II or formula III: wherein, R and Z are each independently a C 1 -C 6 alkyl respectively, M is a C 1 -C 6 alkylene, X is a C 1 -C 4 alkoxy or C 2 -C 4 acyloxy, and n=0 or 1; C. an alkoxy silane derivative having a structure as shown in formula IV: H n SiX (4-n) Formula IV wherein, X is a C 1 -C 4 alkoxy and n is equal to 0 or 1; and D. at least one substance selected from the group consisting of an aqueous dispersion of cationic polymer, an aqueous dispersion of non-ionic polymer and a water-soluble polymer; and wherein component A is present in an amount of from 20 to 45 weight %, component B is present in an amount of from 15 to 45 weight %, component C is present in an amount of from 5 to 30 weight % and component D is present in an amount of from 30 to 60 weight % all based on the total combined weight of components A, B, C, and D.