Paint is applied to the thermoplastic material as part of the mold cycle.

The new In-Mold Coating (IMC) process from ST Machinery Inc. applies paint to heat-resistant thermoplastic as a part of the mold cycle.The result, the company says, is a molded part with a class “A” paint surface, as well as savings in time, equipment and material costs.

In traditional systems, the thermoplastic plastic molded parts, cooled then moved to the finishing area for painting. With the new IMC process, the entire controlled procedure takes place during a single mold cycle. After the part is molded, the tool is opened, paint is injected and the tool is closed again. By controlling the mold position on the electric injection molding machine, a class “A” paint surface that is identical to the cavity surface — free sagging, pinholes and craters — is achieved. In addition, the number of defective parts is reduced since airborne contaminants cannot affect part quality.

Environmentally Friendly Finish

Because the paint is inserted directly onto the product surface, the process achieves a 100 percent transfer efficiency. Also, because the paint is composed of 100 percent solids, no volatile organic compounds are released into the air, which makes it ideal for use by companies in non-attainment zones. Other features of the finishing material include weather and chemical resistance. The specialized paint was developed by Japan-based Dai Nippon Toro (DNT) and is available in the United States from Sherwin-Williams.

The material has been successfully tested on a variety of thermoplastics including ABS, PC/ABS alloy and PC/ASA alloy and can be color-matched to existing products.

Patents for the paint and process have been applied for by DNT and ST. The In-Mold Coating process will become available on ST electric injection molding machines in 2002. As with the Dieprest Skin-Insert Molding Process, it can be retrofitted to existing ST electric machines as well.