MATERIALS | MEDICAL TUBING
consistent peel force within a specific range, avoid chatter marks and residue, and ensure consistent ID and OD tolerancing.
Above: Although
medical waste is routinely discarded and incinerated, there are several
schemes to recycle PVC in hospitals
artery – without harming the blood, and without saline solution.
Fluid transfer Similarly, Alex Kakad, global product manager at TekniPlex Healthcare, highlighted how advances in tubing materials can improve critical fluid transfer applications. Instead of relying on legacy tubing products and specific test criteria, he said, the optimal approach is to perform a comprehensive review of current tubing solutions. This ensures that the best materi- als and construction choices are made in collabora- tion with tubing supply partners, meeting valida- tion and quality considerations. Key design factors for improved tubing include pumpability, inert fluid contact layers, and effective tubing management. He cited the examples of pump tubing for
cardio perfusion pumps. These pumps require tubing that supports a one-week application life, generates low particulates, minimises protein residue build-up, and is solvent bondable. The tubing must also be made from USP Class VI material, comply with Reach standards, and offer better transparency than traditional silicone. Another example was an inert tube design for insulin infusion. Here, the tubing must have low take-up of meta-cresol, and a low extractable product contact layer. The tubing must also maintain an occlusion-free fluid path and avoid delamination under tensile shock testing. A similar tube for glucagon delivery needs to be chemically compatible with DMSO, and be solvent bondable to polypropylene luers and fittings, ensuring a leak-proof fluid path. Tubing management solutions for suction,
irrigation, and power supply also benefit from these advances, he said. The tubing must maintain
18 PIPE & PROFILE EXTRUSION | Summer 2024
Simple tubing Andrew Bunenko, director of business develop- ment at Eldon James, highlighted how ‘simple’ tubing can be applied to a wide variety of medical applications. The secret lies in having a range of options – combined with complementary products. Users need to consider factors such as material, sizing, colour, pressure and temperature ratings, chemical compatibility, and sterilisation methods, he said. Each application has unique requirements, making a one-size-fits-all solution impractical. Understanding the differences between thermo- plastics and thermosets is crucial, he said. Thermo- plastics, such as PE and PU, provide flexibility in design and manufacturing, while thermosets – like some silicones – offer strength and durability but cannot be re-moulded and recycled after curing.
PVC alternatives More recently, at AMI’s European conference on medical tubing, Asahi Kasei Europe revealed details of a new hydrogenated styrenic thermoplas- tic elastomer (SOE) that offers an alternative to traditional PVC tubing. Ryohei Akatsuka, a technology development manager at the company, said the material – SOE L614 – offered high kink resistance, solvent bondability and low absorption of medical drugs, like other grades of SOE. He added that the lack of a plasticiser in SOE meant there were no issues of migration. Other benefits include high transpar- ency and a smooth surface. Potential applications include IV infusion set tubing, pump tubing and spiral tubing. The new grade, compared to earlier grades, has a much higher melt flow rate and slightly higher hardness.
“L614 can achieve high performance without
any trade-off in required properties for medical tubing,” said Akatsuka.
He said the main advantages of the new grade
were its high flowability, high hardness and low stickiness. Adding the material to traditional SOE, in a blend, can also help to modify these properties. “SOE is a practical alternative to PVC and TPU medical tubing,” he said.
Block copolymer At the same event, Kraton said its hydrogenated styrenic block copolymer (HSBC) is another
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