SURFACE TREATED CR-FREE STEEL SHEET FOR USED IN FUEL TANK, PREPARING METHOD THEREOF AND TREATMENT COMPOSITION THEREFOR

摘要

A Cr-free steel sheet includes a Zn-based electroplated steel sheet, a Cr-free layer which is formed by a Cr-free treatment liquid coated on the steel sheet, the Cr-free treatment liquid containing silicate of 3 to 40 parts by weight, silane of 0.5 to 10 parts by weight, titanium compound of 0.2 to 8 parts by weight, binder resin of 10 to 50 parts by weight, the binder resin being selected from the group consisting of urethane resin, epoxy resin and a combination thereof, and phosphoric ester of 1 to 5 parts by weight based on the Cr-free treatment liquid of 100 parts by weight, and a resin layer which is formed by a resin treatment liquid coated on the Cr-free layer, the resin treatment liquid containing melamine resin of 3 to 25 parts by weight, colloidal silica of 10 to 20 parts by weight, metal powder of 5 to 40 parts by weight, and phosphoric ester of 1 to 5 parts by weight based on phenoxy resin of 100 parts by weight.