The demands of the plastics processing industry are constantly increasing. Pigments that are difficult to disperse are also increasingly being used. Methods for determining the dispersion quality are therefore gaining in importance. Following the purchase of a new testing device from Collin Lab & Pilot Solutions in the fall of 2022, Rowa Masterbatch started a six-month testing phase. As part of a master's thesis, this involved investigating the influence of process parameters, such as different screw speed, throughput and split-feed process, in various polymers (LD-PE, PA6 and PMMA) with different, difficult-to-disperse pigments (Pigment Green 7, Pigment Black 7 and Pigment Red 122) and the use of different dispersing additives.
The Filtertest E25E-MP-IS test system with melt pump and integrated screen changer standardizes the test procedure and allows filters to be changed without interrupting operation, thus reducing the pure measurement and evaluation time, depending on the test specification. A laboratory extruder with a 25 mm screw diameter (25 D) was used to prepare the melt. All common engineering plastics up to 300°C can be tested with the system. The test is based on DIN EN ISO 23900-5. The pressure filter test provides an objective parameter for determining the quality of the dispersion of pigments and fillers in masterbatches.