RHEOLOGY Solutions has released a filter pressure value (FPV) test that is suitable for testing colourants in the form of colour concentrates in polymers used for extrusion in melt-spinning processes.
The test mixture is processed in a HAAKE PolyDrive single screw extruder with a non-grooved barrel and a compression screw with additional mixing elements. The polymer melt is fed with a constant pressure of 30 to 60 bar to the HAAKE Melt Pump with a volume of 1.2cm³/rpm.
With this metering pump a constant volume of 50cm³/min to 60cm³/min (setting 660 on the HAAKE Melt pump) of polymer passes the filter package. Particles and agglomerates over a certain size are retained and clog the filter package. A pressure increase is observed and is correlated with the quality of the colourant. The pressure difference between the initial pressure and the peak pressure is used for the calculation of FPV.
Using the test to check raw materials ensures the quality of products and makes the uptime of screen changers more predictable. A full copy of the test method is available on request.