Coated steel sheet and exterior building material
A coated steel sheet comprises: a steel sheet; a primer coating film which is arranged on the steel sheet and comprises an anti-corrosive pigment and an aggregate composed of primary particles; and a top coating film which is arranged on the primer coating film. The anti-corrosive pigment comprises at least one compound selected from the group consisting of a bivalent tin salt, a trivalent vanadium salt, a tetravalent vanadium salt, a tetravalent molybdenum salt, an oxycarboxylic acid salt, an ascorbic acid, a phosphorous acid salt and a hypophosphorous acid salt.
1. A coated steel sheet comprising:
a steel sheet;
an undercoating film disposed on the steel sheet, containing an anti-corrosive pigment and an aggregate being an primary particle, and not containing microporous particle; and
a topcoating film disposed on the undercoating film, wherein
the anti-corrosive pigment is one or two or more compounds selected from the group consisting of a divalent tin salt, a trivalent vanadium salt, a tetravalent vanadium salt, a tetravalent molybdenum salt, an oxycarboxylate salt, ascorbic acid, a phosphite salt, and a hypophosphite salt,
the aggregate satisfies Expression 1 and Expression 2:
D 10 ≧0.6 T (Expression 1)
D 90 <2.0 T (Expression 2)
wherein D 10 is a 10% article diameter (μm) of the aggregate in a number-based cumulative particle size distribution; D 90 is a 90% article diameter (μm) of the aggregate in a number-based cumulative particle size distribution; and T is a film thickness (μm) of the undercoating film at a portion containing none of the aggregate.
2. The coated steel sheet according to claim 1 , wherein a percentage of the aggregate based on a solid content of the undercoating film is 1 vol % or more and less than 10 vol %.
3. The coated steel sheet according to claim 1 , wherein the steel sheet has been subjected to chromium-free chemical conversion treatment.
4. An exterior building material comprising the coated steel sheet according to claim 1 .