Coated metal sheet, method for producing same, and exterior building material

Abstract

This coated metal sheet is for exterior covering, and has a metal sheet and a top coating layer disposed on the metal sheet. The top coating layer is configured from a fluororesin and contains 0.01-15 vol % of microporous particles as a gloss control agent, and the coated metal sheet satisfies the belowmentioned formulae. In the belowmentioned formulae, in the number-based particle size distribution of the gloss control agent, R is the number average particle size (μm), D 97.5 is the 97.5% particle size (μm), Ru is the upper limit particle size (μm), and T is the top coating layer thickness (μm): D 97.5 /T≦0.9; Ru≦1.2T; R≧1.0; and 3≦T≦40.

1 . A coated metal sheet comprising:
 a metal sheet; and   an overcoat coating film disposed on the metal sheet,   wherein the overcoat coating film is composed of fluorine resin,   wherein the overcoat coating film comprises particles having micropores as a gloss adjusting agent,   wherein a content of the gloss adjusting agent in the overcoat coating film is from 0.01 to 15 vol %, and   wherein the coated metal sheet satisfies the following expressions:
     D   97.5   /T≦ 0.9 
     Ru≦ 1.2 T    
     R≧ 1.0 
   3≦ T≦ 40
 
   wherein R (μm) is a number average particle diameter of the gloss adjusting agent, T (μm) is a film thickness of the overcoat coating film, D 97.5  (μm) is a 97.5% particle diameter in an accumulated particle size distribution of the gloss adjusting agent based on the number of particles, and Ru (μm) is an upper particle diameter in the number particle size distribution of the gloss adjusting agent.   
     
     
         2 . The coated metal sheet according to  claim 1 , wherein the Ru is less than the T. 
     
     
         3 . The coated metal sheet according to  claim 1 , wherein the metal sheet has been subjected to non-chromate anti-rust treatment, and the coated metal sheet is chromate-free. 
     
     
         4 . The coated metal sheet according to  claim 1 , wherein the metal sheet has been subjected to chromate anti-rust treatment. 
     
     
         5 . The coated metal sheet according to  claim 1 , wherein the gloss adjusting agent is silica particles. 
     
     
         6 . The coated metal sheet according to  claim 1 , further comprising an undercoat coating film between the metal sheet and the overcoat coating film. 
     
     
         7 . The coated metal sheet according to  claim 6 , further comprising an intercoat coating film between the undercoat coating film and the overcoat coating film. 
     
     
         8 . The coated metal sheet according to  claim 1 , wherein the overcoat coating film is composed of a resin component, as the main component, comprising polyvinylidene fluoride and acrylic resin. 
     
     
         9 . The coated metal sheet according to  claim 1 , having a glossiness at 60° is 20 to 85. 
     
     
         10 . The coated metal sheet according to  claim 1 , being a coated metal sheet for exterior use. 
     
     
         11 . An exterior building material comprising the coated metal sheet according to  claim 1 . 
     
     
         12 . A method for producing a coated metal sheet having a metal sheet and an overcoat coating film disposed on the metal sheet, comprising the steps of:
 applying an overcoat coating material containing a fluorine resin and a gloss adjusting agent onto the metal sheet; and   curing the coating film of the overcoat coating material to form the overcoat coating film;   wherein a content of the gloss adjusting agent in the overcoat coating film is from 0.01 to 15 vol %,   wherein the gloss adjusting agent is particles having micropores, and   wherein the gloss adjusting agent which satisfies the following expressions is employed:
     D   97.5   /T≦ 0.9 
     Ru≦ 1.2 T    
     R≧ 1.0 
   3≦ T≦ 40
 
   wherein R (μm) is a number average particle diameter of the gloss adjusting agent, T (μm) is a film thickness of the overcoat coating film, D 97.5  (μm) is a 97.5% particle diameter in an accumulated particle size distribution of the gloss adjusting agent based on the number of particles, and Ru (μm) is an upper limit particle diameter in a number particle size distribution of the gloss adjusting agent.   
     
     
         13 . The method for producing a coated metal sheet according to  claim 12 , wherein the overcoat coating material has been subjected to treatment for pulverizing the particles in the overcoat coating material.