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25. September 2009

TPE for the cushion in an emergency ventilation mask

The O2-Resq system for providing immediate ventilation in cases of congestive heart failure and other respiratory distress includes a face mask with a soft, rounded elastomeric cushion that fits comfortably on the patient’s face and is free of odour, according to manufacturer Pulmodyne, Inc.

The translucent cushion, or seal, is made of a custom-formulated compound in the Medalist range of medical-grade thermoplastic elastomers from Teknor Apex Company. The soft, 37 Shore A TPE is over-moulded onto the transparent front portion of the mask, which is made of a rigid terpolymer material. Unlike many other elastomers and flexible plastics used in medical masks, Medalist thermoplastic elastomers are odourless, latex-free, and contain no phthalates. Over-moulding the Medalist TPE provides strong adhesion to the rigid substrate and combines the different functions of the soft and hard components into what is in effect a single part. And there are other manufacturing advantages, according to Lisa Charno, Medical Market Manager for the Thermoplastic Elastomer Division of Teknor Apex. “Many medical masks, including Pulmodyne’s O2-Resq model, incorporate undercuts in their design that present real challenges when the part is ejected from the mould,” said Charno. “Because Medalist compounds set up rapidly in the mould and exhibit good tear strength, they make it possible for the mask to be pulled off the mould core without tearing or stretching.” Because the Medalist compound has a lower specific gravity than PVC (0.88 versus 1.13), it yields more parts per pound of compound and makes possible a mask seal that is 22 % lighter than it would have been in PVC. The Medalist programme for medical manufacturers includes a range of 33 standard high-purity compounds along with a comprehensive body of tools and information for designers and processors. Compounds are available with Shore A hardness from 5 to 87 and include clear, translucent, and opaque formulations.

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