Right: An in-line colour measurement probe from ColVisTec installed on a KraussMaffei compounding line processing PP

process, although Gomez says this is a significant change for the industry. “[Processors] have been operating in the traditional way — run production, send sample to the laboratory, do analysis, send results to production, adjust process, repeat — for decades,” he says. “The availability of new tech- nologies makes it possible to create very efficient plants that make instant adjustments, generate a comprehensive analysis of the process and don’t mask costs. A change in paradigm indeed, but to achieve it, companies need to change their mindset and invest in capital and personnel assets.”

Material savings The main benefits of making such changes are savings, particularly in the use of often expensive raw materials. Pigment quality variations are normal as well as variations in their feeding, resulting in too high or too low of a concentration, Gómez explains. Real-time measurements, however, allow immedi- ate adjustments to keep a product within specifica- tion. “In addition to raw materials, think of all the other processing costs associated with a bad run: energy, labour, utilities, operating losses, machine wear and tear, downtime, shipping, packaging and handling losses,” he says. Germany-based ColVisTec also offers an in-line colour measurement system. Its InSpectro X system also combines a spectrophotometer with optical fibre probes that are inserted in the extruder. It assesses process and product stability in the extrusion process through detection of changes that take place in the polymer melt, according to Fuat Eker, Director of Sales, Marketing and Customization at the company. In the InSpectro X system, the in-line UV-VIS

spectrometer measures optical changes in the ultraviolet and visible (UV-VIS) wavelength (220 to 820 nm) spectral range. “By directly observing

variations in the spectrum emitted from the polymer melt, we pick up any change in the process from the polymer itself. Such trends include colour changes, yellowing, degradation, transparency, dosage fluctuations, segregation of premixes, drift and colour/recipe changes. These are effects caused, for example, by change in process parameters such as temperature, pressure, speed, throughput, residence time and material feed,” says Eker. The UV-VIS in-line measurement technology was demonstrated at the K2019 trade fair in Germany on machines of three different extruder manufacturers that partner with ColVisTec: Entex (which makes planetary roller extruders), Leistritz, and KraussMaffei. The latter demonstrated the equipment as part of a liquid colour compounding process and was covered in the July edition of Compounding World.

ColVisTec’s spectrophotomer probes feature a durable self-cleaning sapphire tip

30 COMPOUNDING WORLD | November 2020

Combined spectroscopy For 2020, ColVisTec has added near infrared (NIR) and Raman spectroscopy and introduced its GiANT “3 in 1” spectroscopy platform. It also offers a “2 in 1” optical fibre probe that bundles UV-VIS and NIR fibres in one device that measures and displays information in the spectral range of UV-VIS and NIR (1,000 to 2,300 nm) at the same position in the process and at the same time. “This opens up new and extended possibilities for process monitoring in the extrusion and processing of polymers,” says Eker. For example, he says NIR can be used to measure the residual water content in various polymer applications, while Raman spectroscopy can be utilised for monitoring of chemical reactions during the extrusion process.



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