Method for producing coated metal strip

Abstract

A coating that contains acid-modified polypropylene and that contains 5 mass % or more of nonvolatile matter is applied to a traveling metal strip in a state in which the surface temperature of the metal strip is 60° C. or lower. Next, the coating applied to the metal strip is baked at 80-250° C., and a coating film having a film thickness of 0.3 μm or greater is formed on the traveling metal strip. The proportion of acid-modified polypropylene to resin total mass in the coating film is 40 mass % or higher. The traveling metal strip is then wound after being cooled to a surface temperature of 80° C. or lower.

1 . A method for producing a coated metal strip which is a metal strip having a coating formed on at least one surface thereof, the coating being a part to be joined to a molded article of a thermoplastic resin composition, the method comprising:
 running a metal strip;   applying onto the running metal strip a coating material containing an acid-modified polypropylene, the coating material containing 5 mass % or more of a nonvolatile component, wherein the coating material is applied in a state where a surface temperature of the running metal strip is 60° C. or lower;   baking, at a temperature of from 80 to 250° C., the coating material applied onto the running metal strip to thereby form on the running metal strip a coating with a thickness of 0.3 μm or more;   cooling the running metal strip having the coating formed thereon until the surface temperature becomes 80° C. or lower; and   winding the running metal strip which has been cooled after forming the coating,   wherein a ratio of an acid-modified polypropylene to a total resin mass of the coating is 40 mass % or more.   
     
     
         2 . The method for producing a coated metal strip according to  claim 1 , wherein the coating material further contains an oxide or a fluoride of a metal selected from the group consisting of Ti, Zr, V, Mo, and W, or any combination thereof. 
     
     
         3 . The method for producing a coated metal strip according to  claim 1 , wherein the coating material further contains one or more resins exclusive of the acid-modified polypropylene, wherein the resin is selected from the group consisting of an acrylic resin, an acrylic-styrene resin, an epoxy resin, a vinyl acetate resin, ethylene-vinyl acetate copolymer resin, a fluororesin, a urethane resin, a polyolefin resin, a phenol resin, a polyester resin, a copolymer of the above resins, and a modified product of the above resins. 
     
     
         4 . The method for producing a coated metal strip according to  claim 2 , wherein the coating material further contains one or more resins exclusive of the acid-modified polypropylene, wherein the resin is selected from the group consisting of an acrylic resin, an acrylic-styrene resin, an epoxy resin, a vinyl acetate resin, ethylene-vinyl acetate copolymer resin, a fluororesin, a urethane resin, a polyolefin resin, a phenol resin, a polyester resin, a copolymer of the above resins, and a modified product of the above resins.