2021 年 10 巻 6 号 p. 351-358
This study presents an anodizing process controlling a pore size and surface porosity for injection molded direct joining（IMDJ）. IMDJ is a technique of direct joining between an injection-molded plastic component and a surface-treated metal plate. A surface treated metal plate has a micro-/nano-structure on its surface, which can provide micro-/nano-interlocking with an injectionmolded plastic component. Controlling geometry of a micro-/nano-structure is important to understand how the joining is formed. This study adopted an anodizing process as a surface treatment because it can produce nano-structures, the geometry of which is precisely controlled. To fabricate nano-structures being suitable for IMDJ, a wide variety of conditions for an anodizing process were investigated. Resultantly, we fabricated the nano porous structures that have different sizes but similar porosity: pore diameters of tens nm, 200 nm, and 400 nm approximately. Using the three kinds of metal plates, we investigated the effect of molding condition on joining strength. The results showed that the injection speed, which is one of the molding parameters, had a negative correlation with the strength in any cases of nano-structures. The injection speed effects were also confirmed by an atomic force microscopy of the plastics infiltrating the nano-structures. Under the smaller structures（ tens nm and 200 nm）, we could see same tendency. However, the tendency changed under the 400 nm porous structure condition. The results in the current state cannot give the perfect interpretation of the mechanism of joining occurrence; however it leads the further understanding in future.