Alternatives
TRADITIONAL TO
COATINGS
by Cynthia Challener
JCT COATINGSTECH
Contributing Writer
Paints and coatings offer protection and improve the appearance of many
surfaces. Their value in architectural and industrial applications is undisputed. Yet there are certain instances where alternative technologies can
work better than traditional coatings. In-mold coatings, dry paint films, and
film laminates have earned respect in their own right. These three alternative technologies offer advantages over traditional paints and coatings in a
range of different applications.
With the in-mold coating process, after a plastic part is molded, the
coating is injected into the mold cavity during a specific point in the sub-
strate cooling period.
The injection molding cycle consists of three basic stages: filling, packing, and cooling. The pressure rises at a relatively slow rate during the filling cycle. During the packing phase, shrinkage is offset by maintenance of
very high pressure. During the cooling stage, the pressure in the mold
relaxes. The in-mold coating should be injected during this period. The longer the time between the end of the filling stage and the coating injection,
the lower the packing pressure, but also the lower the substrate temperature. Thus, the ease of injection needs to be balanced with the temperature
required to obtain an adequate curing of the coating.
Control of the mold position in the press, tool surface quality, and film
thickness enables the formation of a high quality paint surface. The process
has been demonstrated on a wide range of small and large parts of varying
geometry and complexity from smooth surfaces to textured and wood grain
appearances.
Dry paint films are multilayer films that include a top clear layer, a
colored layer, and an adhesive layer that are laminated to a backing layer
