Metal material surface treatment process

Abstract

Provided is a metal material surface treatment process capable of providing favorable corrosion resistance, coating film adhesion, and appearance to a metal material. One embodiment of the present invention is a process for surface-treating a metal material, the process comprising: a pretreatment step in which the metal material is treated with a pretreatment agent; a chemical conversion treatment step in which the metal material that has undergone the pretreatment step is subjected to a chemical conversion treatment; and a coating step in which the metal material that has undergone the chemical conversion treatment step is coated, wherein the pretreatment agent contains an amino group-containing compound, and the pH of the pretreatment agent is 6.0 to 12.0 (exclusive of 12.0).

Claims

1. A metal surface treatment process comprising: a pretreatment step of treating the metal with a pretreatment agent; a chemical conversion step of chemically treating the metal after the pretreatment step; and a painting step of painting the metal after the chemical conversion step, wherein the pretreatment agent contains an amino group-containing compound and has a pH of 6.0 or higher and less than 12.

0.

2. The metal surface treatment process according to claim 1, wherein the amino group-containing compound is at least one selected from the group consisting of amino group-containing alkoxysilane compounds and polymers having allylamine units.

3. The metal surface treatment process according to claim 1, wherein the amino group-containing compound is contained in a concentration range of 50 ppm by mass or more and 1,500 ppm by mass or less as solid content relative to the total mass of the pretreatment agent.

4. The metal surface treatment process according to claim 1, wherein the chemical treatment agent used in the chemical treatment step comprises a zirconium compound.

5. The metal surface treatment process according to claim 4, wherein the chemical treatment agent further comprises an amino group-containing compound.

6. The metal surface treatment process according to claim 5, wherein the amino group-containing compound contained in the chemical treatment agent and the amino group-containing compound contained in the pretreatment agent are of the same type.

7. The metal surface treatment process according to claim 1, wherein, following the pretreatment step, the pretreated metal material is chemically treated by the chemical conversion treatment step without going through any other steps.

8. The metal surface treatment process according to claim 1, wherein the amino group-containing compound is an amino group-containing alkoxysilane compound.

9. The metal surface treatment process according to claim 8, wherein the ratio of the solid content mass of the amino group-containing alkoxysilane compound to the total solid content mass of the pretreatment agent is 95% or more.

10. The metal surface treatment process according to claim 1, wherein the pretreatment agent does not contain an epoxy group-containing silane compound.

11. The metal surface treatment process according to claim 1, wherein at least a portion of the metal material is a magnesium material or a magnesium alloy material.

Images