| 摘要 |
PROBLEM TO BE SOLVED: To provide a copper sheet the whole surface of which appears to be natural patina from the beginning by specifying the ratio of a sulfurization-colored coating film and a durable coating material in a surface treated copper sheet produced by applying a durable coating material of such as an aquamarine color fluororesin to a copper sheet on which a sulfurization colored coating film is formed. SOLUTION: After pretreatment of the surface of a base 1a of a copper sheet 1 is carried out to make a coating material easy to adhere to, an aquamarine color durable coating material 2 of such as fluororesin is applied and fixed to the resultant copper sheet. At that time, the quantity of the coating of the aquamarine color durable coating material 2 is so set as to be at (40:60) (60:40) ratio to the surface of the base 1a of the copper sheet 1. After that, a sulfurization-colored coating film 1b is formed on the resultant base 1a of the copper sheet 1. As an easy desulfurization coloration method, a concentrated solution of potassium sulfide sold at a market as a domestic tufaceous agent for hot-spring bathing is one example and in this method, the surface of the base 1a of the copper sheet 1 is uniformly sulfurized by repeating brushing and sodium bicarbonate is used together in the case of accelerating the sulfurization. |
