US 12,030,082 B2
Bilayer composition for surface treatment of steel plate and surface-treated steel plate using same
Chang-Hoon Choi, Pohang-si (KR); Won-Ho Son, Pohang-si (KR); and Hee-Jea Eun, Pohang-si (KR)
Assigned to POSCO CO., LTD, Pohang-si (KR)
Appl. No. 17/416,210
Filed by POSCO, Pohang-si (KR)
PCT Filed Sep. 18, 2019, PCT No. PCT/KR2019/012020
§ 371(c)(1), (2) Date Jun. 18, 2021,
PCT Pub. No. WO2020/130295, PCT Pub. Date Jun. 25, 2020.
Claims priority of application No. 10-2018-0165449 (KR), filed on Dec. 19, 2018.
Prior Publication US 2022/0055067 A1, Feb. 24, 2022
Int. Cl. B05D 7/14 (2006.01); B05D 7/00 (2006.01); C09D 5/08 (2006.01); C09D 7/61 (2018.01); C09D 7/63 (2018.01); C09D 133/08 (2006.01); C09D 171/00 (2006.01)
CPC B05D 7/14 (2013.01) [B05D 7/52 (2013.01); C09D 5/086 (2013.01); C09D 7/61 (2018.01); C09D 7/63 (2018.01); C09D 133/08 (2013.01); C09D 171/00 (2013.01); B05D 2202/15 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A bilayer composition for surface treatment of a steel plate, comprising:
an undercoat coating composition comprising 1 to 12 wt % of a phenoxy resin, 0.001 to 1.0 wt % of colloidal silica, 0.001 to 1.0 wt % of a silane coupling agent, 0.1 to 1.0 wt % of a corrosion inhibitor, 0.001 to 1.0 wt % of a phosphoric acid compound, and a balance of water, based on a total weight of the undercoat coating composition; and
a topcoat coating composition applied to the undercoat coating composition to be dried, and comprising 0.1 to 5.0 wt % of an acrylic acid resin, 30 to 50 wt % of colloidal silica, 40 to 60 wt % of alkoxy silane, 5 to 15 wt % of an acrylate-based monomer, 0.01 to 1.00 wt % of an acidity control agent, and a balance of an organic solvent, based on a total weight of the topcoat coating composition,
wherein the corrosion inhibitor is at least one selected from the group consisting of hexafluorozirconic acid, hexafluorotitanic acid, ammonium hexafluorozirconate, and ammonium hexafluorotitannate,
wherein the phosphoric acid compound is at least one selected from the group consisting of polyphosphoric acid, phosphoric acid, zinc phosphate, manganese phosphate, phosphoric acid derivatives, and phosphorous acid,
wherein a thickness of the undercoat coating is 0.001 to 10 μm and a thickness of the topcoat coating is 0.1 to 50 μm.