In 1998, several companies founded the “CEN Committee Filtertest” (CEN Committee Pressure Filter Test): BASF, Clariant, Degussa, Ciba, GABRIEL-CHEMIE as well as Dr. COLLIN GmbH, Brabender Messtechnik and Thermo Electron – manufacturers of laboratory lines for the plastic processing industry.
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This initiative had the aim to develop a standardized method for the determination of the pressure filter value – valid for the total plastic processing.
At the MASTERBATCH 2004 in Cologne, it finally happened: With the EN 13900-5, the CEN Committee presented a unique measuring method with which the suitability of pigments for the colouring of plastics can be described. The novelty of this measuring method is that the extruders used for the pressure filter test must be equipped with standardized screen packages and the pre-pressure must exactly be defined.
Moreover, the melt pump must have a constant, defined output and the measured pressure must be within a prescribed range. Here, the following rule applies: The lower the pressure filter test, the better the dispersed pigment and the higher the product quality.
The Standard EN 13900-5 causes that, in future, for the pressure filter test, the extruders have more or less the same design.
Only for the operation of the integrated software and the way the screen is installed, differences are conditionally permissible.
The manual COLLIN pressure filter test is used for determining quality differences in a polymer caused by agglomerates, insufficiently dispersed fillers resp. contaminations.
For example, the pressure filter test can be used in the field of product development for optimizing colour master-batches, for quality control or for incoming and outgoing inspection of masterbatches, compounds, polymers or recycled polymers.
The material to be tested is molten and homogenized in an extruder and, via a melt pump, discharged through a screen with a defined and constant volume flow. Particles of a certain size clog the screen and thus the open area of the screen is reduced. This results in an increasing pressure in front of the screen which is measured by a sensor.
