Parameters Affecting the Ink Wash-off in In-mold Decoration of Injection Molded Parts

Abstract Ink wash-off has been one of the problems that has confounded the overall success of the in-mold decoration (IMD) process for injection molded parts. In this report, an experimental matrix design based on the Taguchi method was conducted to examine the influence of processing parameters on the ink washoff of molded parts. The resins used in the study were 20% glass fiber filled poly(ethylene terephthalate) (PET). A commercially available PET film pre-printed with grids was employed to prepare the parts. Specimens of three different thicknesses were molded using a pin injection gate on an injection molding machine with a reciprocating screw system. After molding, the severity of ink washoff was determined by an image analysis program. The experimental results suggested that molded composite parts of smaller thicknesses exhibited more severe ink washoff. For the parameters selected in the experiments, the melt temperature and mold temperature were found to be the principal factors affecting the ink...