A printing plate for gravure printing consisting of five layers of aluminum alloy / anodic oxide film / nickel / polypyrrole / copper was fabricated by anodizing, electro-less plating, electroplating, and electro-polymerization. Nickel layers were first deposited on anodic oxide film-covered aluminum alloy by electro-less plating and electroplating. The polypyrrole layer was then deposited on the nickel layer by anodic polarization in a pyrrole monomer solution. Many copper fine particles were deposited on the polypyrrole-deposited specimen at the initial stage of electroplating in the CuSO4 / H2SO4 solution; then a continuous copper layer was obtained through longer cathodic polarization. The copper layer with polypyrrole was removed easily from the nickel layer by pulling with adhesive tape, which suggests that the structure is useful as a reusable aluminum printing plate by copper electroplating and electro-polymerization.
The authors, using sodium hypochlorite solution, hydrochloric acid, and sodium chloride, prepared acidic synthesized water having the same characteristics and composition as an anodically electrolyzed sodium chloride solution (acidic electrolyzed water). The following findings were obtained by investigating the characteristics of each solution and the dissolution behavior of copper. 1) The dissolved oxygen concentration and free chlorine concentration decrease immediately after electrolysis in acidic electrolyzed water. Their rates of decline are higher than in acidic synthesized water. 2) The dissolution rate and surface morphology of copper immersed in the respective solutions are almost identical. 3) Free chlorine in these solutions accelerates the dissolution rate. The dissolved chlorine increases the surface roughness of copper. 4) Oxygen nanobubbles probably exist much in acidic electrolyzed water. 5) Dissolution behavior of copper immersed in acidic electrolyzed water differs between during electrolysis and after electrolysis. Dissolution rate of copper is larger, and surface was not roughened in acidic electrolyzed water during electrolysis. These phenomena are presumably attributable to the actions of hydroxyl radicals generated during electrolysis.