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In-Mold Coating

The in-mold coating (IMC) process incorporates coating into the molding process. This process reduces the amount of solvents needed and provides beneficial environmental impacts. The use of IMC with injection-molded parts has the potential for reducing, or eliminating, the volatile organic compounds associated with the painting process. To date, the IMC process has been successfully applied to sheet molding compound compression-molded parts to provide a primed surface that can then be electrostatically painted in a separate process. This project seeks to analyze the technical feasibility of replacing the painting process with in-mold coating for plastic injection molds.

The Technology

In mold coating was first developed and applied to sheet molding compound compression-molded parts. The coating is carried out by injecting a liquid-reactive coating material onto the substrate, i.e. the molded part, while it is still in the mold. This process provides a conductive layer for electrostatic painting.

The objective of this project is to evaluate thermally activated curing systems that work at lower temperatures and mixed coating systems (two part or three part) for use as an electrically conductive primer or as a class-A finish.  We will evaluate different fillers and nano-fillers that may provide the required coating properties, including hardness, substrate adhesion and conductivity. Both experiments and computer simulation will be used to evaluate the various coatings.  An important part of the project will be to evaluate the chemorheology of the coating systems and to determine how the fillers affect the curing process.

For two or three-component systems, we will evaluate the mixing process and how it relates to coating performance, especially adhesion. It is likely that we will have to modify a standard mixing system to operate under high pressure as standard systems are intended to operate at ambient or slightly elevated pressures.  This will be a key part of the research if the use of a two or three-part coating is desired.