Colored polymer components provide functionality and aesthetics in medical applications. Colors are used to differentiate product type, size, or model. Certain colors may even convey meaning, such as reds or yellows for warning notification.
Common Coloring Techniques
Colored polymer components can be produced from masterbatch concentrates (blended into natural polymer prior to molding or extruding) or pre-colored polymers via melt blending/compounding. The selection of one coloring method over the other may vary based on economics, secondary operations and end application.
Foster Corporation has processing capabilities to manufacture both masterbatch and pre-colored polymers. Our experienced team of material scientists and process engineers are available to select the most appropriate coloring technique for your requirements.
Pre-Colored Compounds vs. Masterbatches
Masterbatches or color concentrates provide an economical solution for long manufacturing runs of high volume parts. Sufficient setup time is required to ensure the concentrate is properly blended prior to and during the melt processing phase in order to achieve the desired color consistency from part-to-part. This investment may be offset by the economies gained from using a high proportion of unmodified polymer at a reduced price.
The use of masterbatches however, can present several challenges. Metering un-dried masterbatches into hygroscopic resin may impart additional water, which may cause undesirable part appearance, processing and or performance issues. Also, masterbatches require additional handling that may be inconsistent with the natural polymer to which it is added; subsequently resulting in potential production variability. Concentrate pellets are also denser than the natural polymer pellets and tend to sift downward in the hopper, often leading to variable loading levels and color drifts throughout a production run. Although the use of color metering weigh feeders can minimize variation, it also requires additional equipment and production controls. This in turn, reduces the potential cost savings for short production runs.
Pre-color compounds and masterbatches can be manufactured using FDA Food Grade Pigments listed under FDA 21 CFR part 173-178 or using FDA Medical Device Pigments listed under FDA 21 CFR Parts 73 and 74. For medical applications, the selection of one pigment classification over the other may affect the FDA approval process.