| 摘要 |
PROBLEM TO BE SOLVED: To enhance the waterproof adhesivity of a coating film without impairing any working adhesivity by adjusting the silica primary grain size and the total silanol group of a silica coating film for sealing a phosphate coating film. SOLUTION: In a chemical-converted steel sheet in which a phosphate coating film provided on a hot-dip zinc-plated layer is sealed with a silica coating film, the silica coating film contains no silane coupling agent, and the primary grain size of silica particles forming the coating film is adjusted to 10-200 nm, and the total silanol group obtained as the product of the silanol group per 1 mg of silica particles by the silica adhesion per 1 m<SP>2</SP>is adjusted to be in a range of 1.1×10<SP>15</SP>to 8.5×10<SP>18</SP>, respectively. COPYRIGHT: (C)2007,JPO&INPIT
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