Teknor Apex: Flexible vinyl medical compounds with enhanced heat stability

A new family of flexible vinyl compounds exhibits greater resistance to heat-generated discoloration or degradation than conventional medical-grade PVC, enabling device manufacturers to increase productivity and quality assurance, it was announced today by Teknor Apex. The company’s Vinyl Division introduced the compounds today at MD&M West (Booth 2430).
All vinyl compounds contain heat stabilizers to prevent degradation of the PVC polymer during processing, shipment, or storage. The enhanced-stability series in Teknor Apex’s Apex (R) product line incorporates stabilizers that are more efficient than those in conventional medical grades of vinyl, according to Peter M. Galland, industry manager.

‘Because they withstand the heat and shear of melt processing better than conventional medical-grade vinyl, our new compounds enable extrusion processors to run at higher rates and with fewer screen changes,’ Galland said. ‘Injection molders have greater assurance that vinyl will stand up to the shear forces developed when filling molds for complex or thin-wall parts.’

Quality also improves, and not just in products fresh from the processing machine, Galland added. ‘Medical devices can undergo high-heat conditions at many points in their post-production lifetimes. They can be shipped in hot trucks, stored in hot places, or autoclaved. We anticipate that the new formulations used by Teknor Apex will further extend shelf life.’

Teknor Apex is offering the new compounds as alternatives to conventional Apex formulations (which will continue to be available) in the same range of durometers. All are clear, Galland noted, but Teknor Apex expects to develop compounds for opaque applications. The new enhanced-stability products, also available from Teknor Apex’s Singapore Polymer Corporation subsidiary in Asia, include these series:

—CLEAR EXTRUSION: Apex 3700 compounds (alternatives to Apex 3300) for such tubing applications as blood transport and delivery, enteral feeding, oxygen delivery, dialysis, catheters, and drainage systems. Another new series for the same range of end uses, Apex 3701, incorporates plasticizer formulations that are alternatives to standard DEHP (like the conventional 3301 series).

—CLEAR INJECTION MOLDING: Apex 3800 compounds (alternatives to Apex 3200) for applications such as oxygen masks, mouthpieces, adapters, valves, connectors, drip chambers, and syringe bulbs. In addition, the new Apex 3801 series contains alternative plasticizers (like the conventional 3201 series).

Compounders have been unable to make use of the best available heat stabilizers in medical-grade vinyl formulations because of regulatory restrictions on ingredients in medical products, Galland said. ‘One of the most efficient families of heat stabilizers, for example, is that of barium-zincs, but such heavy metal-containing heat stabilizers are more highly regulated than the calcium-zinc formulations typically used in conventional medical-grade vinyl compounds. Calcium-zincs, on the other hand, exhibit substantially less capability than barium-zincs for retarding heat-degradation when PVC encounters ‘hang-ups,’ ‘dead spots,’ or high shear during processing or is stored under high-heat conditions.’

The innovative Apex medical compounds are heavy metal-free, Galland noted. ‘Our compounds utilizing the new stabilizer formulation provide early color and long-term heat stability similar to that obtainable with the most efficient non-medical stabilizers. In addition, they exhibit clarity and compatibility equivalent to or better than conventional medical vinyl.’

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