| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface treatment liquid for a self-deposition coating treatment, which shortens a period necessary for the step compared to a conventional coating step, hardly produces a by-product such as a sludge which is harmful to an environment, is superior in a throwing power for an inner part of a sack structure part, does not use a component such as a chromium compound which is harmful to an environment, has corrosion resistance, and can further overcoat a baking paint on the obtained paint film. SOLUTION: The surface treatment liquid for forming the self-deposition coating film on a metal material is an aqueous solution containing a novolak resin having a methylol group, a cross-linking agent, ferric ions, elemental fluorine and an oxidizing agent, in which the cross-linking agent has a cross-linking group that can cause a thermosetting reaction with a methylol group and a phenol nucleus and/or a phenolic hydroxyl group, a ratio of a mass concentration of a solid content in the novolak resin to that in the cross-linking agent is in a range of 1:1 to 1:10, the mol concentration of the elemental fluorine is at least three times of that of the ferric ion, and the pH is in a range of 2 to 6. COPYRIGHT: (C)2010,JPO&INPIT
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