MATERIALS | MEDICAL TUBING
tubing in certain applications. A new polybutene grade of polypropylene (PP),
called Purell KT Mr 07, is a high molecular weight material. It offers relatively low oligomer content, low extractables and a plasticiser-free formulation. The material is also soft, flexible and transparent. Its reduced adsorption of active pharmaceutical
Above: Purell KT MR 07 PB-1 plastomer from LyondellBasell enhances low temperature toughness and impact resistance of PP medical tubing
– for an implant. Trelleborg needed to overcome several dimensional and visual quality issues on an existing design. To do this, it determined a specifi- cation for design of spiral winding equipment, and created processes to control final length and remove the core. Overall, it achieved 99% yield, advanced the
process technology and capabilities, and received customer validation for the manufacturing processes. Part of the reason for the project’s success was
early – and frequent – collaboration during the design process, he said. Final benefits included faster time to market and reduced operating costs.
Multi-layer choice Choosing the correct materials in a multi-layer design is important for medical tubing. Bernd Elbert, business development manager for health- care and packaging at Ineos Styrolution, told delegates that its new Styroflex thermoplastic elastomers (S-TPEs) help to imbue tubing with rubber-like mechanical properties, high puncture resistance and good transparency and heat resistance. Its Styroflex 4G80 grade has a range of proper- ties making it suitable for medical tubing, including good kink resistance and good bondability to other parts of an IV system. It has been used for both mono- and multi-layer tubing. It showed stable performance over time when pumping saline solution, and produced accurately sized tubes over a range of processing tempera- tures. In combination with Styrolux, it has been used to make multi-lumen tubes. Overall, the Styroflex grade maintained clarity and lubricity, gave sufficient roller clamp perfor- mance and was cost competitive, he said.
PO replacing PVC A joint project from materials supplier LyondellBa- sell and extrusion specialist Maillefer has shown that polyolefin tubing can replace traditional PVC
18 PIPE & PROFILE EXTRUSION | September 2019
ingredients allows more precise dosage of medi- cines to be used, it said. The grade is around 25% less dense than an equivalent grade of soft PVC. It can also be blended with similar grades to create a compound with superior properties. “The material is a cost-competitive alternative to
traditional materials, which is easily processable in the form of a compound or as a dry blend,” said Ankur Rastogi, of Basell Polyolefine. The material was processed on Maillefer’s
PML-32 medical extrusion line, which runs at 240 m/min. It was used to produce a variety of different samples, using various product formulations and production speeds – in order to test both dimen- sions and surface qualities. A barrier screw with a pin mixing section was
used, and both barrel head and extrusion head temperatures were held close to 180°C. A variety of tubes were produced at lines speeds between 72 and 150 m/min.
Both dry blends and compounds processed in a similar way to medical PVC. Surface properties depended on the formulation, while extrusion tool size had to be adapted to account for die swell. “The softer the material, the more it is elastically
stretched in the cooling line,” said Daniel Schläfli, R&D project leader and patent manager at Maillefer. “This translates to a reduction of the diameter in-line – for identical product diameter – but it recovers off-line.” n The next Medical Tubing conference is held in Minneapolis, USA on 5-6 November 2019. For more details, contact Charmaine Russell
(
charmaine.russell@
ami.international) on +44 (0) 117 924 9442.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.ami.international �
www.bostonscientific.com �
www.raumedic.com �
www.spectrumplastics.com �
www.exgineering.com �
www.freudenbergmedical.de �
www.trelleborg.com �
www.ineos-styrolution.com �
www.lyondellbasell.com �
www.maillefer.net
www.pipeandprofile.com
PHOTO: LYONDELLBASELL
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