To improve the adhesion of the coating film on a poly ethylene terephthalate (PET) sheet, surface modification of the PET sheet was implemented by applying atmosphere pressure plasma processing utilizes a cylindrical shaped rotary electrode. After processing in the following conditions : (He : O2=99 : 1, rotating speed 5.2m/s (φ120mm rotary electrode), machining gap 500μm, RF power 300W, scanning speed of worktable 300mm/min, machining time 30sec), the existence of the hydrophilic group (-C-OH,-COOH) which contributes to the wettability of the PET sheet was observed, and surface texture which contributes to the anchoring effect was obtained. The peel strength of the coat film on the PET sheet was also improved sharply without a surface treatment by an organic solvent.
This paper aims to evaluate the mold releasing properties of DLC (Diamond Like Carbon) film coating on the injection mold. The thin walled plastic products need bigger mold releasing force than the ordinary products in the opening stage of the plastics injection molding process. Reducing mold releasing force by the mold surface modification makes stable production. DLC film coating was performed on the injection mold for reducing the mold releasing force and compared with non-treatment and hard chromium electroplating. Furthermore, the sliding friction coefficient between the DLC film specimen and PMMA resin was measured under the different surface temperatures, and each surface property was investigated by SPM (Scanning Prove Microscope) from a microscopic standpoint. As the result of cross-section measurement and evaluating the bearing length ratios of two perpendicular axes, the surface of the DLC film coating was remarkably smooth and had no sharp edges or directionality that compared with nontreatment and hard chromium electroplating specimens. Such characteristics restrain the deformation and adhesion of the outer layer part when the product slides on a metal surface. DLC film coating has shown 27%-35% less releasing force than the ordinary surface treatments.
The hot hardness of Ni-W-P alloy deposits of various W and P contents were measured using a hot hardness tester. The hot hardness increased with the elevation of the temperature and indicated the maximum value, depending on the W and P contents of the deposits. The hardening of the alloy deposits with elevated temperature would be caused by precipitation of Ni, Ni4W and Ni3P particles from an amorphous structure.