PROCESSING | INLINE MEASUREMENT
results which can quickly be translated into process changes. This is distinctively different from ‘frozen’ design-of- experiment setups where it is necessary to wait up to several weeks for the analytical results to be available, Eker says. “Concerning produc- tion, every company that contemplates turning a batch
process into a continuous
Above: ColVisTec
developed its ‘2-in-1’ probe as part of its GiANT spectrometer development programme
Right: The GiANT from ColVisTec is a ‘3-in-1’ inline spectrometer offering UV-VIS, NIR and RAMAN as a complete solution
or reactive extrusion process must carefully evaluate the need for inline and real-time monitor- ing in order to secure consistent quality,” he says. “Every case where a short interruption in the dosing system can cause a significant quality issue is a good case for inline process monitoring.” The recycling sector is a particularly suitable sec- tor for the use of inline monitoring technologies, he says. “The incoming materials vary significantly, and it is only by converting this to stable end-prod- ucts that good prices and high-end reuse can be achieved.” According to Eker, all of the factors driving the adoption of inline measurement in the compound- ing industry —shorter development cycles, smaller batch sizes, improved production stability — benefit from availability of the certified quality logs that can be produced when quality is monitored continu- ously. Technical issues relating to new product and process developments, for example, can be addressed through use of residence time distribu- tion measurements and other com- plex/comprehensive data analyses. The company has developed
its RTM (Residence Time Meas- urement) and ReTA (Residence Time Analysis) software tools specifi- cally to meet this need. They enable analysis and visualisation of spectral data to characterise the extruder for screw configuration, for example, and for process parameters such as the influence of speed on dispersion quality, as well as recipe/formulation development.
“In addition to the now well-estab- lished UV-VIS inline spectroscopy, we see additional opportunities for our RAMAN and NIR inline spectroscopy for advanced applications,” says Eker. “GiANT is a ‘3-in-1’ inline spectrometer platform with the three spectrometers
36 COMPOUNDING WORLD | November 2021
— UV-VIS, NIR and RAMAN — as a complete solution in one unit. GiANT makes it possible to generate a comprehensive view of the extrudate.” Two combinations of these spectrometers are
currently available and said to be of particular interest to the polymer processing industry — UV- VIS+NIR and UV-VIS+RAMAN. The inline NIR spectrometer, for example, detects residual moisture in the polymer melt while the UV-VIS spectrometer indicates process stability and/or variation in colour values. “As part of the GiANT development programme, we have in our product range a very advanced ‘2-in-1’ combined single probe,” Eker says. “This combination probe offers the advantage of recording UV-VIS and NIR information at the same measuring point in the extruder and it eliminates the need for location and time offset on the extruded product. In addition, there is no need for a second ½ inch-20UNF bore, where there is typically limited space available at the die plate.” Working with a number of plastic compounders,
ColVisTec says it has addressed areas such as dispersion and distribution quality and homogeni- sation, as well as quantifying ‘carbon’ in black compounds and pigment concentrations. “We have been working with early adopters in the compounding industry for a number of years,” Eker says. “Our systems now run 24/7 at production sites around the world, providing real-time moni- toring for our customers, as well as aiding them in their R&D and product development process.
Deep learning
Inline viscosity and colour measurement can be reasonably well-established technologies, according to Collin Lab & Pilot Solutions, but the company says that a number of new measuring methods — such as Near Infrared (NIR) systems, ultrasonic measurement and optical coherence tomography (OCT) — are increasingly finding their way into inline measuring equipment. These include methods for deep machine learning and AI-algorithms that provide a new point of view on inline measure- ments and the results that they generate. With closed loop control systems, active process control can now also be achieved. Collin highlights the key purposes of inline measurement systems for plastics compounding as monitoring for quality assurance, keeping the process stable, and targeting process and/or product
www.compoundingworld.com
IMAGE: COLVISTEC
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