Chemical conversion coated plated steel sheet and method for producing same

Patent metadata

Field	Value
Publication number	US-9890461-B2
Application number	US-201514922341-A
Country	US
Kind code	B2
Filing date	Oct 26, 2015
Priority date	Jun 18, 2010
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

The present disclosure relates to a chemically treated zinc-based plated steel sheet that is superior in weather resistance, water resistance, blackening resistance and film adhesion. A chemical conversion film having a thickness 0.5-10 μm is formed by coating and drying a chemical treatment solution on a surface of an aluminum-containing zinc-based alloy plated steel sheet. The chemical treatment solution contains a fluororesin containing 0.05-5% by weight of a hydrophilic functional group selected from the group consisting of a carboxyl group and a sulfonic acid group and 7-20% by weight of a fluorine atom, the fluororesin in which a number-average molecular weight is 1,000-2,000,000, and an oxoate, a fluoride, a hydroxide, an organic salt, a carbonate or a peroxygenated salt of a group 4A metal.

First claim

The invention claimed is:

1. A method of preparing a chemically treated zinc-based plated steel sheet, the method comprising:
preparing an aluminum-containing zinc-based alloy plated steel sheet, the aluminum-containing zinc-based alloy including 0.05-60% by weight of aluminum; and
forming a chemical conversion film having a thickness of 0.5-10 μm, by coating and drying a chemical treatment solution on a surface of the aluminum-containing zinc-based alloy plated steel sheet, wherein:
the chemical treatment solution contains a water-based emulsion of a fluororesin and a group 4A metal compound,
the fluororesin contains 0.05-5% by weight of a carboxyl group or a salt thereof and a sulfonic acid group or a salt thereof, and 7-20% by weight of a fluorine atom, the fluororesin having a number-average molecular weight of 1,000-2,000,000,
the group 4A metal compound includes an oxoate, a fluoride, a hydroxide, an organic salt, a carbonate or a peroxygenated salt of a group 4A metal;
an amount of the group 4A metal compound is within a range of 0.1-5% by weight in terms of metal with respect to the fluororesin; and
a molar ratio of the carboxyl group to the sulfonic acid group included in the fluororesin is 5-60.

2. The method of preparing the chemically treated zinc-based plated steel sheet according to claim 1 , wherein the chemical treatment solution further contains a phosphate, and an amount of the phosphate with respect to the fluororesin is within a range of 0.05-3% by weight in terms of phosphorus.

3. The method of preparing the chemically treated zinc-based plated steel sheet according to claim 1 , wherein the chemical treatment solution further contains a silane coupling agent, and an amount of the silane coupling agent with respect to the fluororesin is within a range of 0.5-5% by weight.

4. The method of preparing the chemically treated zinc-based plated steel sheet according claim 1 , wherein the group 4A metal compound comprises a group 4A metal selected from the group consisting of Ti, Zr, Hf, and any combination thereof.

5. The method of preparing the chemically treated zinc-based plated steel sheet according to claim 1 , further comprising:
forming a preliminary chemical conversion film by coating and drying a preliminary chemical treatment solution on a surface of the aluminum-containing zinc-based alloy plated steel sheet before forming the chemical conversion film, wherein the preliminary chemical treatment solution contains a valve metal salt and a fluoride ion.

Assignees

• Nisshin Steel Co Ltd

Inventors

• Matsuno Masanori
• Ueda Koichiro
• Yamamoto Masaya
• Taketsu Hirofumi

Classifications

• C23C22/34

  containing fluorides or complex fluorides · CPC title

• C23C2222/20

  Use of solutions containing silanes · CPC title

• C23C22/361

  containing titanium, zirconium or hafnium compounds · CPC title

• C23C22/44

  containing also fluorides or complex fluorides · CPC title

• C23C28/00 Primary

  Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D · CPC title