Surface treatment agent for zinc or zinc alloy coated steel sheet, zinc or zinc alloy coated steel sheet, and method of producing the steel sheet

Patent metadata

Field	Value
Publication number	US-9512331-B2
Application number	US-201113581146-A
Country	US
Kind code	B2
Filing date	Feb 25, 2011
Priority date	Feb 26, 2010
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

The present invention provides a chromium-free surface treatment agent, comprising: a resin compound having a specific bisphenol skeleton; cationic urethane resin emulsion; silane coupling agent; an organic titanium chelate compound; a quadrivalent vanadyl compound; a molybdic acid compound; and water, wherein these components are blended at predetermined ratios such that pH value of the surface treatment agent is in the range of 4 to 5. The one-pack type chromium-free surface treatment agent of the present invention exhibits good stability during storage and is capable of forming on a metal material surface a coating film excellent in corrosion resistance at a bending-processed portion of a steel sheet, solvent resistance and paintability after alkali degreasing.

First claim

The invention claimed is:

1. A surface treatment agent for a zinc or zinc alloy coated steel sheet, comprising:
(A) resin compound having a bisphenol skeleton represented by general formula (I) below;
(B) cationic urethane resin emulsion having at least one type of cationic functional group selected from primary amine, secondary amine, tertiary amine or quaternary ammonium salt;
(C) at least one type of silane coupling agent having at least one type of reactive functional group selected from active hydrogen-containing amino group, epoxy group, mercapto group armor methacryloxy group;
(D) organic titanium chelate compound;
(E) quadrivalent vanadyl compound;
(F) molybdic acid compound; and
(G) water,

such that conditions (1) to (5) below are satisfied, pH of the surface treatment agent being in the range of 4 to 5,
wherein: (1) [(B s )/{(A s )+(B s )+(C s )}] as a mass ratio of solid content (B s ) of the cationic urethane resin emulsion (B) with respect to total solid content {(A s )+(B s )+(C s )} of the resin compound (A), the cationic urethane resin emulsion (B) and the silane coupling agent (C) is in the range of 0.1 to 0.3;
(2) [(C s )/{(A s )+(B s )+(C s )}] as a mass ratio of solid content (C s ) of the silane coupling agent (C) with respect to total solid content {(A s )+(B s )+(C s )} of the resin compound (A), the cationic urethane resin emulsion (B) and the silane coupling agent (C) is in the range of 0.6 to 0.85;
(3) {(C s )/(D Ti )} as a mass ratio of solid content (C s ) of the silane coupling agent (C) with respect to mass content (D Ti ) in terms of titanium of the organic titanium chelate compound (D) is in the range of 50 to 70;
(4) {(E V )/(D Ti )} as a mass ratio of mass content (E V ) in terms of vanadium of the quadrivalent vanadyl compound (E) with respect to mass content (D Ti ) in terms of titanium of the organic titanium chelate compound (D) is in the range of 0.3 to 0.5;
(5) [(F Mo )/{(A s )+(B s )+(C s )}] as a mass ratio of mass content (F Mo ) in terms of molybdenum of the molybdic acid compound (F) with respect to total solid content {(A s )+(B s )+(C s )} of the resin compound (A), the cationic urethane resin emulsion (B) and the silane coupling agent (C) is in the range of 0.003 to 0.03;

in formula (I), Y 1 and Y 2 bonded to benzene rings, respectively, are each independently hydrogen or group z represented by general formula (II) or (III) below, the average substitution number of the group z per benzene ring is in the range of 0.2 to 1.0, and n represents integer in the range of 2 to 50:

in formula (II) and formula (III), R 1 , R 2 , R 3 , R 4 and R 5 each independently represent hydrogen atom, C 1-10 alkyl group or C 1-10 hydroxyalkyl group, and A − represents hydroxyl ion or acid ion.

2. The surface treatment agent for a zinc or zinc alloy coated steel sheet of claim 1 , further comprising (W) wax,
wherein [(W s )/{(A s )+(B s )}] as a mass ratio of solid content (W s ) of the wax (W) with respect to total solid content {(A s )+(B s )} of the resin compound (A) and the cationic urethane resin emulsion (B) is in the range of 0.2 to 0.4.

3. A method for manufacturing a zinc or zinc alloy coated steel sheet, comprising:
coating a surface of a zinc or zinc alloy coated steel sheet with the surface treatment agent of claim 1 or 2 ; and
drying the zinc or zinc alloy coated steel sheet thus coated such that the peak temperature of the steel sheet is in the range of 50° C. to 180° C. to form a surface treatment film on the surface,
wherein a film coating weight of the surface treatment film per one surface after the drying process is in the range of 0.2 g/m 2 to 1.8 g/m 2 .

4. A zinc or zinc alloy coated steel sheet, having a surface treatment film provided thereon such that a film coating weight of the coating film per one surface of the steel sheet is in the range of 0.2 g/m 2 to 1.8 g/m 2 ,
wherein the surface treatment film is obtainable by coating a surface of the zinc or zinc alloy coated steel sheet with the surface treatment agent of claim 1 or 2 and drying the zinc or zinc alloy coated steel sheet thus coated such that the peak temperature of the steel sheet is in the range of 50° C. to 180° C.

Assignees

• Imokawa Toru
• Fujibayashi Nobue
• Kubota Takahiro
• Hamada Etsuo
• Nagoshi Masayasu
• Jfe Steel Corp

Inventors

• Imokawa Toru
• Fujibayashi Nobue
• Kubota Takahiro
• Hamada Etsuo
• Nagoshi Masayasu

Classifications

• C09D7/1233

  Chemistry & Metallurgy · mapped topic

• C09D5/084

  Inorganic compounds · CPC title

• C09D175/04 Primary

  Polyurethanes · CPC title

• C08K5/56

  Organo-metallic compounds, i.e. organic compounds containing a metal-to-carbon bond · CPC title

• C09D165/02

  Polyphenylenes · CPC title