PETG Foam-Core Sheet Cushions Thermoformed Medical Packaging

New option is lighter, cleaner, tougher than HIPS at a comparable price.

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A durable, economical, and styrene-free alternative to HIPS for protective medical packaging is realizing its first commercial applications, with more on the way. First launched in early 2014 by Eastman Chemical Co., Kingsport, Tenn., Eastalite copolyester is being used to extrude multilayer sheet with a foam core. The concept was presented at the MD&M East Show in N.Y.C. in June by Eastman together with two partners in commercializing the product.

The coextruded sheet consists of foamed Eastalite copolyester, Eastman’s first opaque medical-grade material, between two solid skins of Eastman’s Eastar 6763 PETG. The latter has been used in clear, rigid medical packaging for more than 20 years. The result is a lightweight, amorphous, opaque sheet with impact-resistant cushioning properties and a nonporous physical barrier to microbes. Eastman and its partners see this sheet structure as presenting numerous opportunities in thermoformed protective packaging for pharmaceuticals and medical devices, as well as medical kits and work-in-process trays.

The first North American extruder of Eastalite sheet is Pacur of Oshkosh, Wis., the largest producer of PETG sheet for medical uses. The foam-core sheet’s PETG skin layers allow for the same heat-seal and product-contact surfaces familiar to the medical industry. “We didn’t want to introduce a whole new material, just to present it in a different form,” says Jim Banko, v.p. of sales. What’s more, it accepts printing better than HIPS, he says.

One of the first thermoformers of Eastalite sheet is Tek Pak Inc., Batavia, Ill., which specializes in product development and prototyping. Its first application is close to commercialization, awaiting FDA approval. The formed package, made from Pacur’s PETG Foam with Eastalite, will provide cushioning protection for a heart pump worth upwards of $100,000, according to Tony Beyer, president and owner of Tek Pak. Several other applications are also close to commercial launch, he adds.

Beyer sees several advantages to Eastalite sheet over HIPS: “We were able to run the thermoformer about 5% faster with the Pacur PETG foam than with an equivalent polystyrene material. Eastalite forms easier than HIPS and its lower forming temperature requires less heating and therefore less cooling. It forms crisply, which is good for snap fits. The material is easily trimmed and has a beautiful pearlescent look.”

Trimming, he notes is a particular advantage for medical applications. “We found it to trim cleaner than HIPS, with less generation of angel hair and particulates. And the cut edges are not sharp like HIPS, which can puncture a sterile barrier.”

Aneta Clark, Eastman’s market development manager, notes that besides overall system cost savings, Eastalite foam-core sheet offers further advantages over HIPS. It allows design freedom with deep undercuts and more durable living hinges. It is tougher and more resilient, not brittle, and shows less stress-whitening than HIPS. It is also lightweight—typical density of the overall sheet is around 0.080 g/cc, vs. 1.05 for HIPS and 1.27 for solid PETG.

Tek Pak’s Beyer sees market potential for Eastalite and Pacur’s foam-core sheet beyond the medical sphere: “Anything that requires shock absorption and cleanliness—such as fragile electronics.” Consumer packaging is another possibility, he says.

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