Polyketones | materials
Originally launched onto the plastics market back in the 1990s, polyketone was discontinued in 2000. It is now available once more and its unique performance offering is drawing attention, writes Jennifer Markarian
Unique properties drive the polyketone revival
Aliphatic polyketone (PK), which was available from Shell under the brand name Carilon in the mid-1990’s but was discontinued in 2000, underwent a rebirth in 2013 when South Korea’s Hyosung Corporation - after ten years of development and more than fi fty patents - began marketing product from a pilot-scale plant. In July last year, the company started up a 50,000 tonne per annum (110 million lb/yr) commercial plant for its brandname Poketone resins and announced plans for a second plant to start up after 2020. The unique properties of PK are a result of its
semi-crystalline molecular structure, which alternates between carbon monoxide (CO) and olefi n. Hyosung says it can make both terpolymer (ethylene, propylene, and CO) and copolymer (ethylene and CO) polyketones. However, all grades currently offered by the company are terpolymers, which have better processability (in both moulding and extrusion applications) compared to copolymer
form.The copolymer does have some interesting mechanical properties, with better heat resistance and strength than PA66, but its processability is a drawback, says Cliff Watkins, marketing director at US-based distributor PolySource. Hyosung’s technology is also capable of producing terpolymers with other monomers, but these are in an early R&D stage. Such polymers could be designed for lower processing
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temperatures, which could take advantage of PK’s inter- esting adhesive and cohesive properties for use as a tie-layer resin, according to Watkins. Hyosung’s current slate of terpolymers produced at
its commercial-scale plant is broad and includes a high-fl ow grade (M230A); a medium-fl ow grade (M330A) for injection moulding; a low-fl ow extrusion grade (M630A); and a very low-fl ow grade (M730A) for profi le extrusion and blow moulding. All of these grades melt at 220°C. The company also makes a low-fl ow, lower melting point grade (M620A) for extrusion applications, where a slightly lower temperature is needed. It melts at 204-210°C and is currently produced at pilot scale but could be produced at commercial scale if demand warrants, the company says. Another pilot-scale grade is M930A, with a medium-high MFI (165 g/10 min). Two new grades developed by Hyosung include M340 for high impact strength and M640 for high heat resistance. The company plans to further expand its product portfolio as the market demands. Customers that previously had used Carilon are
fi nding improved mechanical properties and enhanced colour matching with Poketone, says J H Park, presi- dent of Hyosung Chemical performance group. The alternating structure on the PK polymer backbone (CO and olefi n) results in properties such as
March 2016 | COMPOUNDING WORLD 15
Main image: Good process- ing and a novel property set means newly available
polyketone
compounds are attracting interest
PHOTO: LEHMANN & VOSS
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