materials feature | Polyolefins
Medalist TPE from Teknor Apex can
replace PVC in products like blood bags
combination of higher heat stability and strong processing,” said Wilfried Hatke, European marketing and sales manager for Topas.
Medical advance Teknor Apex, in a collaboration with O’Sullivan Films and Genesis Plastics Welding, has developed a way to make products like blood bags from TPE rather than PVC. Calendered films made from its Medalist MD-500 series of elastomers can overcome the traditional disadvantages of TPEs in applications such as fluid drainage and storage bags, cushioning bladders and surgical pouches, it says. Calendered PVC film is widely used in medical
Natpet’s new thermoforming grade of PP boasts high clarity and aesthetics
applications but TPEs have not performed well in in this process – which typically provides better thickness uniformity, more consistent physical properties and greater thermal stability than film extrusion, says Teknor. Teknor and O’Sullivan have shown that Medalist MD-500 Series medical elastomers can be formulated for successful calendering. “We attempted to calender a wide range of plastics besides PVC and concluded that most are simply not calenderable,” said Chuck Stronach, commercial manager for healthcare products at O’Sullivan Films. “We were intrigued to discover that Medalist 500 Series compounds can be adapted for this process.” Elliott Pritikin, global medical market manager for the TPE division at Teknor Apex, said that new material offered property improvements over PVC, along with weight and cost savings: film made from the material was half the thickness of PVC, for the same strength; and its density is around 30% lower, allowing weight savings of up to 70%. Medalist elastomers are also available at lower
hardness ranges than flexible PVC, provide a broader processing window, and have greater elasticity and tear strength. They also exhibit 25% less colour change on
exposure to gamma irradiation than standard grades of flexible PVC. The third partner, Genesis Plastics Welding, was
able to use its proprietary radio frequency (RF) welding technology, EcoGenesis, to form strong permanent bonds in complex geometric patterns – including sealing two mono-layered films to tubing, to make traditional infusion bags.
Coating performance There were also advances in polymers for coating. Sabic says it has optimised production of its extrusion coating grade LDPE NexCoat 5. The material is produced by Sabic’s CTR tubular process to create a resin that outper- forms traditional autoclave grades, says the company. Customers have the chance to reduce inventory costs and simplify processes, because the material can replace grades with melt indices ranging from 4 to 8. At the same time, Sabic says that NexCoat 5 has a
15-20% lower carbon footprint than standard market grades.
Other than food and liquid packaging, it can be used in
a variety of other extrusion coating applications, including imaging, release liners and building and construction. It can also be used in lamination applications. Rob Balk, international account manager at Sabic,
said: “NexCoat 5 is a drop-in solution and customers can replace multiple grades with this one product.” The grade has a low neck-in, which produces a
stable web. Other properties include: the ability to process at higher line speeds; high adhesion to various substrates; and excellent sealing properties. Borealis has been working in a similar area,
34 FILM & SHEET EXTRUSION | January/February 2014
www.filmandsheet.com
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