TESTING/MEASURING: Online Color Spectrophotometer for Extrusion

Equitech to showcase newest UV and visible color spectrophotomer for continuous monitoring of extruded plastics.

Designed to provide a continuous measurement throughout the color compounding process, the latest Equitech Online Color Spectrophotometer (OCS), which will be demonstrated by experts from Germany’s Equitech International (U.S. office in Augusta, Ga.) at NPE 2015, is also designed for use as a process control tool to diagnose the extrusion line. The OCS can directly monitor parameters such as yellowness (b*), feeder stability, screw wear, ideal temperature profile and screw speed.

The OCS with the Reflection Polymer Melt Probe and the Transmission Polymer Melt Probe for opaque and transparent plastics, respectively—is designed for color measurement in molten plastics in the extrusion process. It reportedly can accurately measure the color and consistency of many polymers, ranging from PE, PP, PS and PVC to PET, PC, ABS, acrylics, nylons, and fluoropolymers.

Equitech’s probes feature a rugged design with a sapphire window that provides the interface between the optical fibers and the process, and which perform in process temperatures of up to 932 F and pressures of up to 5000 psi. This is said to allow for continuous update of process color changes for optimal process control.

Equitech’s areas of expertise are applications for extruded polymers, with an emphasis on working with recycled materials, which pose a particular challenge due to the variation of product characteristics including color and contamination. The OCS allows processors to constantly measure the molten polymer prior to the die. This measurement, says Equitech, can accurately predict final color numbers (in L* a* b*) and other color space. Alarm capabilities provide the tool operator with the data resources needed to segregate off-spec material.  With the use of color measurement as feedback to a control system, closed loop control can be achieved to effectively dose brighteners (TiO2) and pigments.