As material and cost-control options are assessed for rigid trays, designs must bow to operating room requirements.
By David Vaczek, Senior Editor
|For packaging acetabular cups used in hip replacement surgery, a system from Barger Packaging uses BargerGard polyeurethane to replace multiple configurations of foam, reduce the number of package components, and protect the implant to the point it goes into the body.
In the design of rigid packaging, converters are often serving two audiences, with requirements that are potentially in conflict. As OEMs look to minimize packaging material and production costs, designers must account for the ultimate end-users’ preferences.
Converters welcomed insights provided by an updated survey of operating room nurses’ estimation of packaging that was presented at HealthPack 2009.
“We look to studies like this for insights on nurses’ preferences and needs, because it’s not easy for us to get good information from the end-users,” says Edward Haedt, VP, marketing, Perfecseal (Oshkosh, WI).
Nurses by a wide margin favored a double sterile tray-in-a-tray configuration. The packaging should allow easy access to inner packaging and the device in the operating room. It needs to maintain the device’s sterility, as it is presented to the sterile field, nurses reported in an AORN survey by Clemson University.
“When we design the packaging, we [think] beyond the device manufacturer to the end-user,” says Dick Simmons, medical business manager, rigid packaging, Alga Plastics (Cranston, RI), a part of Sealed Air Corp. “We design so the nurse can stay in the control of the product.”
Barger Packaging (Elkhart, IN) supplements insights gained from studies such as the AORN survey with on-site hospital visits, says Mike Auger, VP, sales, Barger Packaging.
“We try to work with our customers and have them understand that working with their marketing and field sales teams early on in the packaging design stage can help with speed to market,” says Auger. “They are the closest people to their end-users, the clinicians and nurses, [from whom] we want to get their valuable input.”
Auger notes that commercial considerations may dictate the use of as little plastic as possible, such as by shrinking the package footprint to conserve storage space. Nurses, on the other hand, may prefer larger finger holes that might dictate a larger package size.
“There are always trade-offs as we work on new designs to help reduce the packaging costs, allow for smaller footprints, and light weighting, while making certain the end-user requirements are not overlooked,” Haedt says.
Package design goes hand in glove with the rigid packaging material used. Materials must be matched to the application requirements. Offering advantages including high clarity, toughness, and excellent thermoformability, PETG prevails as the rigid packaging material of choice.
“PETG has a proven track record in the medical packaging market based on many years of successful performance and use,” says Jennifer Lauderback, sales engineer, Brentwood Industries (Reading, PA). “Accelerated aging and shelf life studies have been completed, so PETG is a known entity.”
Plastic Ingenuity (Cross Plains, WI) has developed its SafeEdge tray in PETG, and in a lower cost HIPS. Formed in one mold to an outer dimension size of 9.5 × 7 in., SafeEdge features a rounded tray edge that protects secondary pouches from pin holes and punctures.
“We [hear] feedback on additional sizes [such as a] 12 × 14-in. tray,” says Jason Crosby, medical business manager.
“Most OEMs like to have the ability to look through the sterile barrier system to confirm the contents,” Crosby adds. “Using blue-tinted PETG promotes visual inspection as seal channel breaches and curls in the Tyvek show up more clearly.”
A catheter tray from Brentwood Industries features a clear PETG lid that snaps to a HIPS base.
Despite PETG’s advantages, converters cite increasing interest in alternative materials. Cost reduction is one trend, and barrier materials promise options for OEMs looking for flexible packaging alternatives.
“The device side is becoming more price-sensitive due to competition and pressures for cost reduction from healthcare providers,” says Crosby. “This is true particularly for commodity products, where the package cost is a higher percentage of the overall cost.”
Polypropylene (PP) has gained ground as a lower cost option for medical packaging.
“Thermoforming technology has improved for processing PP, and the material has improved with the addition of melt strength enhancers and clarifiers,” says Dave Rosten, medical sales manager, Brentwood Industries. “PP provides a level of barrier, and contact clarity, an increased level of barrier protection, and also has good contact clarity.” Brentwood Industries has seen a spike in PP sales in the past 18 months.
“PP is used more and more in the medical device industry,” he says. “It has a better barrier than PETG and HIPS, and a higher heat distortion temperature. PP will withstand all types of sterilization. Polycarbonate is the only other material with this type of [sterilization] flexibility, but it is much more expensive.”
The Perfecseal and Curwood divisions of the Bemis company regularly thermoform different grades of PP, says Haedt.
“PP as a resin is a relatively low-cost raw material,” Haedt says. “[But] it is much more challenging to thermoform into [complex] mold designs.”
“Most PP grades are also less durable and stiff than PETG,” he adds. “At the end of the day, when considered for a complicated thermoforming mold, PP does not offer all the efficiencies that PETG provides.”
APET and RPET provide alternatives for packaging lighter-weight products, at 30–40% less cost than PETG. Brentwood Industries’ customers use the materials for secondary packaging for vaccine vials, or for nonsterile clamshell packaging.
A clear HIPS tray insert snaps to the base of a HIPS medical tub in this design from Brentwood Industries.
Recycled PET (polyethylene terephthalate) cannot be accepted for sterile products, as medical device packaging requires traceability back to the raw material lot. But OEMs are favoring the material, in part to support their own internal green programs, says Lauren Foos, national accounts manager, Placon (Madison, WI).
Placon this year began selling its EcoStar RPET in rollstock form. EcoStar PC50 contains a minimum of 50% postconsumer recycled PETE.
Companies that sterile-fill ampules and vials use RPET for secondary packaging. Other applications include clamshells, in-process and handling trays, and glucose meter packaging, Foos says.
“RPET provides great clarity and high impact strength, while helping to keep waste out of landfills,” Foos says. “Our designs always include crisply formed stack features to ensure high-speed automated denesting. RPET offers cost-savings over PETE, and especially over PETG.”
Placon has launched EcoStar HS 1000 Sealable RPET, with 35% postconsumer content, supporting use of uncoated Tyvek lidding. “Customers can use any material to seal to HS 1000 including films and paper lidstock,” Foos says.
HIPS is often used as a low-cost material in outer packaging components. While clarified HIPS has promised to expand applications in styrene materials, utility is limited.
“The opaque styrene is a big workhorse for procedural commodity-type trays,” says Simmons. “We run a lot of HIPs and clarified HIPS [but] . . . it lacks the toughness of PETG, so you have to design carefully to avoid crazing or blushing in stressed areas.”
Brentwood Industries runs the clarified styrene in a handful of applications, for example for an inner tray used with an outer HIPS tray.
“Clarified styrene is another cost-effective option, but we have moved away from it and are no longer selling it for medical devices. We were seeing too many carbon and gel specs in the material. They don’t affect the package performance, but they create a perception that the package is unsterile or unclean,” Rosten says.
Converters have tested a variety of materials to impart higher levels of barrier characteristics to rigid packaging, as an oncoming wave of drug and device combo products fuel requirements for barrier protection.
Gary Hawkins, technical platform manager for medical packaging, Eastman Specialty Plastics (Kingsport, TN) says OEMs are trying to understand how much barrier they really need.
“At Eastman, we are trying to gauge the barrier needs of the marketplace, both for medical devices and other applications, and derive solutions using our polymers,” he says. “We have some proprietary, patentable compounds for moisture and oxygen barrier [for use in] mono- and multilayer structures.”
“The challenge with any kind of barrier material is that the drawdown or final wall thickness is not uniform,” Hawkins says. “You can do calculations to estimate the barrier, but you can’t predict the thinning precisely. Often, you won’t know the precise barrier performance until you do the shelf-life testing.”
Deep-drawing PCTFE more than an inch or so for rigid trays is problematic.
“PCTFE has far better moisture barrier per mm thickness than most materials, but it just doesn’t draw down that well,” Hawkins says. “We have seen PCTFE/PETG laminates used as a replacement for foil packaging, where the customer is looking for structure and visibility in packaging of skin grafts and artificial tissues. [But] industry is looking for other barrier material solutions.”
Eastman has worked on a five-layer coextruded Eastar copolyester 6763 PETG/COC structure.
“With COC, you have to go thicker to get a comparable barrier to PCTFE, but the advantage is the cost, and you can draw it down,” Hawkins says. “Also, some medical device manufacturers report occasional air bubbles trapped in at the adhesive layer of the PCTFE and PETG laminations. This may be seen as a defect or as impairing the sterile barrier.” The PETG/COC multilayer coextrusion process does not allow air bubble entrapment in the sheet, he adds.
“We have a lot of experience with multilayer COC co-ex films,” says Haedt. For oxygen barrier, Perfecseal/Bemis deploys PET/EVOH/PET structures that provide better barrier than Barex, he adds.
Tim Kneale, market development manager, Topas Advanced Polymers, Inc. (Florence, KY), says that converters are offering structures of COC in symmetrical coextrusions with PETG (PETG/COC/PETG) for providing clear, deep-draw barrier.
In confronting the pressures of the current economy and increasing competition, OEMs are requiring more services from their suppliers.
“The medical device manufacturers are pushing back on the formers to perform more process validations on machinery, processes, and products, even though the OEM will have to perform validation on their packaged product,” says Lauderback.
“Excellent quality is a prerequisite, while innovative designs, rapid prototyping, and new material insights help to differentiate your company,” she adds.
Auger at Barger notes that as some OEMS have imposed internal hiring freezes, they are looking more for outsourced expertise. “We are involved more in the initial package design, and doing more capability studies at our machine center,” he says. “We also have been called on to help sell the package concept internally at the OEM. In these days of cutbacks, the customers often want us to work faster to increase their speed to market. They want us to nail it the first time.”
In the area of controlling packaging costs, spiking resin prices of recent years have spurred medical device packagers to investigate alternative materials. Most recently, they’ve seen another avenue for cost reduction.
“We have seen record drops in resin prices, compared to six months ago” says Rosten.
“[That’s] significant because resin is probably one-half the cost of the package. Many medical device companies are trying to lock us into three-year contracts,” he says.