MAINTENANCE | PURGING COMPOUNDS
clean resins, such as PPS, PEEK, LCP and PEI, while the PF grade is suitable for hot runner cleaning and can be used as a sealing material during machine shutdowns,” he says. Asaclean recently tested its Plus grade to optimise colour changeover efficiency from grey to orange on a twin-screw extrusion production line. The test results showed that thorough equipment cleaning before purging and regular breaker plate and screen maintenance are critical factors for achieving efficient colour transitions. Implementing these best practices reduced purge time, material usage and contamina- tion risks, enhancing productivity output. Maintenance and production departments are
Above: A clean pair of
compounding screws after removal of the Asaclean purge
and barrel, such as twin-screw extruders, can use purging compounds,” Sanchez says. “The main trends and influences driving new developments in purging compounds are environ- mental and economic pressures, as well as aca- demic education. These factors demand waste and energy reduction, risk prevention, and quality and efficiency improvement in compounding process- es. New developments addressing these needs include purging concentrates, high-temperature purging compounds and glass-filled mechanical purging compounds, that can clean different resins, additives and contaminants at various processing temperatures,” he says. In practical terms, Asaclean also emphasises the
importance of selecting the right type and amount of purge for different applications, resins and additives. It also points out it may be necessary to adjust the processing parameters to enhance purging efficien- cy. Factors such as screw speed, feed rate, tempera- ture, pressure and vacuum devices may need to be managed, depending on the purge and the resin used, and higher screw speed and lower feed rate generally improve cleaning performance. Asaclean says its latest developments include the Plus concentrate, PF and PX2 grades. “This purging concentrate is especially suitable for hot runner colour changes, blow moulding and most extrusion applications,” says Sanchez. “They are easy-to-use because they match the
production resins’ MFR, do not require changing processing temperatures, and their loading ratios can be adjusted to optimise cleaning power. PX2 and PF grades are both high-temperature purging compounds that can clean super-engineering resins at processing temperatures of up to 420°C. They have excellent thermal stability. The PX2 grade has superior cleaning power for hard-to-
52 COMPOUNDING WORLD | December 2023
now more open to using premium purging compounds to optimise cost and time in a more efficient way, says Mathieu Rioult, Commercial Manager at Polytechs. He says that current trends influencing new developments in purging com- pounds include supporting the reintroduction of recycled resins in extruders, which are more sensitive to gels and carbonisation. Solutions are also being developed that clean polymer produc- tion systems in a more sustainable way through recyclable purging compounds and purges for biopolymers, for example. The latest Polytechs developments include
Clean HP for cleaning barrier polymers. The company says that purging EVOH production with Clean HP is four times faster than a special purge for EVOH and requires four times less material. Contaminants remain within the EVOH purge. Developed for biopolymers, Clean Xpress is said to purge three to six times faster than virgin resins with up to ten times less material. The company adds that it has also refined its procedures to provide guidelines for cleaning specific recipes. Polytechs says it can provide advice on the right
product required for a colour or resin change, problems with black specs or purging with a weekend compound. This will also include ensur- ing that the purging compound is suitable for the processing equipment. Polytechs highlights a recent example in cable production, where cleaning an XLPE production line, four times a month, generated a cost saving of 15% and created more than 100 extra hours in capacity.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.chemtrend.com �
www.rapidpurge.com �
www.voelpker.com �
www.dynapurge.com �
www.asaclean.com �
www.polytechs.fr
www.compoundingworld.com
IMAGE: ASACLEAN
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