TECHNOLOGY | PROCESSING
Multiple recycling of PE Source: ColVisTec
reactors. A combined UV-Vis and NIR fibre probe allows simultaneous measurements at the same location, which reduces the number of bores in the extruder die. The new RedLog software module manages extensive data processing and can open, display, and compare large amounts of data over various periods (daily, weekly, monthly, or yearly) in two or three dimensions. Eker said the software facilitates data analysis and simulation replay, which complements the existing software suite of CVT- trend for real-time trend diagrams, ReTA for resi- dence time analysis, and SpecViewer for rapid spectral analysis. Recent work between SKZ (South German
Detection of PE contamination in PP Source: ColVisTec
the extrusion equipment, ensuring smooth and optimal conditions, product quality monitoring ensures that the final product meets specific standards. These types of monitoring are interre- lated; stable machine parameters lead to consist- ent product quality, and feedback from product quality monitoring guides adjustments in machine settings to enhance the process.” Eker said that in-line measurement should be able to detect changes in raw materials, such as segregation of premixes; powder flowability issues; degradation from thermal and shear stress; and the level of dispersion and homogeneity achieved in a process. “It should also characterise the com- pounding efficiency of specific screw configura- tions for particular materials at given throughputs and evaluate the performance of upstream and downstream equipment such as feeders and melt filters. Our in-line monitoring equipment meets these requirements, operating 24/7. Additionally, our equipment significantly accelerates product development by reducing the time needed to develop recipes, adapt screws, and explore and confirm optimal process windows.” The company initially focused on ultraviolet-visi-
ble (UV-Vis) spectroscopy. More recently ColVisTec added near infrared (NIR) and Raman-based spectrometers for extrusion, mixing processes, and
16 COMPOUNDING WORLD | August 2024
Polymer Institute) and ColVisTec involved develop- ing an automated colour control system for com- pounding recycled materials. Another new tool detects the degree of contamination, such as the PE content as an impurity when recycling PP. This important information about the impurity content is recorded directly in the polymer melt in real time via the fibre optic probe that is installed in the extruder die or after the melt filter. The InSpectro NIR from ColVisTec with a spectral wavelength range of up to 2,300 nm is used for this measurement.
Colour measurement Measuring the colour of a compound or master- batch during production to check that it is meeting the specification has traditionally been performed by taking samples from the process line to the lab and measuring the colour off-line using a lab spectrophotometer. “The problem with this method is that it is only one point in time. It doesn’t account for process disruptions that can affect colour, such as a feeder that doses an incorrect amount of pigment or titanium dioxide for some period of time, or an overheating process zone that burns the polymer and causes it to yellow. Only an in-line spectrophotometer that measures colour through- out the production run can provide this data,” said Joe Golba, Vice President of Innovation and Implementation at Equitech International. The company’s in-line spectrophotometer systems use special fibre optic probes that are inserted into the melt to provide real-time data during production. Golba said that one challenge is that in-line
measurement is still more expensive than labora- tory measurement. Some companies that have experienced a significant quality control problem are able to quantify the cost that could have been avoided with in-line measurement, but others see the technology as a ‘nice to have’ rather than a ‘must have’. Equitech is working on designs that will help make in-line measurement more competitive
www.compoundingworld.com
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