Flexible Packaging: Revisiting Flexible Packaging
Medical companies are investigating top- and bottom-web alternatives for the flexible packaging of higher-value and sensitive medical devices.
By David Vaczek
By David Vaczek
The advent of newer films is prompting medical device companies to reevaluate their flexible packaging. Solutions such as clear high-barrier films and multilayer coextrusions have promised enhanced packaging features and performance, in some instances with the advantage of reducing cost.
“The value of medical devices and the performance demands placed on them continue to increase. Customers expect new packaging solutions to deliver consistently better performance over incumbent designs while being more cost-effective from a holistic perspective. Medical device manufacturers are also beginning to realize that packaging can play a vital role in establishing an image or differentiating a brand in the market,” says John Richard, North America business manager, DuPont Medical and Industrial Packaging. Because of greater adoption of novel packaging materials such as peelable films, “we are experiencing significant interest and growth in Tyvek 2FS, as it offers the optimum balance between device protection, superior performance to medical grade papers, and total package cost-effectiveness,” he says.
Multilayer coextruded bottom webs incorporating higher-performance materials are providing cost advantages through downgauging. “The medical market has really embraced our seven-layer film,” says Edward Haedt, director of marketing, Perfecseal Inc. (Oshkosh, WI). “These films can be engineered to have more durability, with a thinner structure, and therefore net a better savings. A little bit of nylon goes a long way to add puncture, abrasion, and flex-crack resistance. You can downgauge some films by up to 50%, without sacrificing, and possibly enhancing, the structural properties of the packaging,” he says.
Perfecseal’s latest multilayer nylon film uses a layer of polyester to eliminate mold shrink, the one slight drawback to nylon-forming films, Haedt explains. “The polyester conforms to the forming mold and holds the detail of the mold with almost no shrink back,” he says.
Boston Scientific (Maple Grove, MN) is developing new medical devices that will require new packaging materials. The Maple Grove location develops and manufactures stents, balloon and guide catheters, and catheter guide wires, all of which are packaged with premade pouches, says Tim Mlsna, director of packaging. After numerous acquisitions of smaller companies, the company has pared its packaging-related vendor base from more than 100 suppliers to less than 20, including “three or four converters” for sterile barrier packaging. It formed a packaging council in 2001 to “evaluate the requirements of the company as whole. We are trying to test the materials that will meet all of our needs. We don’t have the time or money to test every material, so we make decisions based on our suppliers’ abilities, and our interest in specific materials. We are currently evaluating and testing many new materials that will potentially be used throughout the entire corporation. Cost is one area we continually try to address, but our first and foremost priority is quality and safety,” he says.
WEIGHING PEELABLE FILMS
Peelable films have improved in recent years, but fiber tear, price, and strength under certain sterilization conditions are limiting wider adoption, say some users.
Solutions using coated Tyvek sealed to a standard bottom web have remained more consistent than structures using peelable films in providing fiber-tear-free peels. Peelable films sealed to uncoated top webs are most promising when weighed as alternatives to uncoated Tyvek sealed to standard bottom webs, such as PET/PE, says one expert. In those cases, packagers may gain improvements in fiber tear and widen sealing windows.
Boston Scientific uses tons of Tyvek a year. Many of its pouches use coated Tyvek 1073B sealed to various poly bottom webs.
“We are evaluating or testing peelable films from every one of our vendors right now. They are all promoting a wider machine-sealing range with these materials. One of our biggest concerns is fiber tear. We have historically seen that our coated materials have less of a propensity for fiber tear than the peelable films. Most peelable films are designed so that the peelable layer fails internally. Historically, many companies have had a difficult time getting that to happen consistently,” Mlsna says. “With peelable films, we do anticipate a reduction in fiber tear when converting from uncoated Tyvek structures,” he says.
“Generating fiber-tear-free opening performance is the largest hurdle the peelable films need to overcome. The challenge before both Tyvek and peelable film manufacturers is to not compromise customers’ expectations relative to feel and performance versus coated designs. However, the benefit of achieving these objectives can be considerable savings over heat-seal-coated structures,” says Richard. “Our perception is that the science and knowledge surrounding uncoated Tyvek/sealable film structures has improved. As a result, more companies are considering adopting them. These designs tend to offer better process control and more-consistent seal strengths than standard polyester/poly bottom web films, but they are not necessarily as robust as heat-seal-coated top web materials,” he says.
Film composite sealant selections are dependent upon the application and the sterilization method used, says Edward Verkuilen, marketing manager for Rollprint Packaging Products Inc. (Addison, IL). Rollprint’s Allegro peelable sealant technology can be applied to aluminum foil composites and to Clearfoil to provide peelable clear high-barrier film composites. The Allegro T peelable sealant was specifically developed to provide a consistent peelable seal from uncoated Tyvek and paper.
“We can modify the sealant resin blend to get the control and seal strength that our customers require. Typically, Allegro provides a clean peel transfer,” Verkuilen says.
Alcoa Flexible Packaging Inc.’s (Richmond, VA) Integripeel peelable lidding with Alcoa’s proprietary cohesive peeling film has been used successfully in contact lens packaging as lidding for blisters. Alcoa is now recommending it for autoclaved pouches, such as for surgical blades and sutures, where it would seal to itself, says James Stevenson, senior technical specialist.
“Using Integripeel in this application, you can more easily achieve a full-panel opening, as opposed to a notch-tear opening. Also, it has a very broad sealing window. We have found in the food industry that shelf life increases using this peelable film technology, instead of coated foils. Although we have not quantified that in the drug industry, we expect similar improvements,” Stevenson says.
Amcor Flexibles’ (Madison, WI) Core-Peel peelable film provides a seal window that is “very similar to coated products, due to the way in which the Core-Peel “seal/peal” system works,” says Bob Liesenfelt, product director, coated and laminated products.
“Core-Peel has been gaining acceptance for products that are gamma sterilized, and the mating web is a flexible polyolefin material,” he says. Core-Peel is being used in thermoform-fill-seal and four-side-seal package designs for products including catheters, gloves, small instruments, and dressings, Liesenfelt says.
Haedt says that Perfecseal’s CleanPeelTransfer films have posted growth due to their lower cost compared with heat-seal-coated alternatives. “The CPT technology works well, but is not, at this point, as friendly as the low-temperature heat-seal coatings used today on the porous webs. Perfecseal continues to improve this technology and someday expects it will improve to the point of having broader use in the market,” he says.
Yet Jeff Murak, director of marketing and sales, Oliver Products (Grand Rapids, MI), says that price has been an obstacle to the wholesale adoption of peelable films. “The combined package cost is still the issue. The peelable films may offer a little better price, but they have lacked the significant savings that the medical device manufacturers are looking for as an incentive to change,” he says.
EKOS (Bothel, WA) employs uncoated Tyvek sealed to standard bottom webs for its pouch applications. EKOS manufactures side-hole and end-hole catheter drug delivery systems that employ ultrasound to modify the texture of blood clots and make them more permeable to drugs. The electrical and hydraulic catheters require substantive packaging. Catheters go into carrier tubes. The tubes are packaged into thermoformed PETG tray-and-lid units supplied by Prent Corp. (Janesville, WI). Mangar Industries Inc. (New Britain, PA) supplies premade pouches to hold the trays using uncoated Tyvek 1073B sealed to PE/Mylar (PET), says Steve McKelvy, packaging/manufacturing engineer, EKOS.
“This is old-fashioned stuff. But it has never been proven to me that the sealable films have the robustness of the films we use. Early on, experience with the newer films led me to believe they may be more susceptible to delamination when they are sterilized more than twice. We have more experience with these older films, and changing a film is an incredibly involved process,” McKelvy says.
“My sealing window is narrower. But I can manage that. We think the seal strength is comparable, and I don’t have fiber tear, because our pouch supplier reliably provides a consistent product. On the top web, the uncoated Tyvek provides the enhanced permeability we need for EtO sterilization,” he says.
Some applications, however, may require coated Tyvek. Tolas Healthcare Packaging (Feasterville, PA) is launching a heat-seal coated Tyvek with static dissipative properties, reports Leslie Love, vice president of sales and marketing for Tolas. “The coating dissipates or removes the charges that are common with high-speed Tyvek processing. It could minimize the particulate drawn to materials through static electricity,” she explains.
Demand has increased for clear high-barrier film alternatives to foil. “We have the seen the demand for ClearFoil composites grow tremendously in the last three years,” says Rollprint’s Verkuilen. ClearFoil composites are used in lidding and pouch applications, where there is a need to see the product through the highbarrier material.
Aclar has gained acceptance in formable applications when features such as transparency and moisture barrier are desired. “Aclar and Aclar laminates are being used in the pharmaceutical market and in nonmedical packaging. Aclar has the best moisture-barrier properties of any formable material on an equivalent thickness basis. For extremely moisture-sensitive products requiring formed packaging and see-through clarity, Aclar has no equal at this time,” says Haedt.
Honeywell Specialty Films (Morristown, NJ) says that its latest Aclar grade, Aclar Flex, extends the flexible packaging applications for Aclar and provides up to double the barrier value of other Aclar grades in top-web applications. Aclar Flex can be used as a flexible web in pouches, overwraps, and lidding, where Aclar’s properties of moisture barrier, transparency, and flex-crack resistance are desired, says Remco van Weeren, market segment leader, healthcare.
“When people hear the name Aclar, they think of a stiff material that is being used for thermoforming and blister packaging as part of a laminate. Aclar Flex provides a top-web solution for flexible packaging as well.” Aclar Flex is manufactured with an orientation process, which allows it to significantly increase the barrier versus the traditional Aclar barrier materials.
Thermoforming—reheating—will negate Aclar Flex’s enhanced barrier value. “When laminated to a poly film and thermoformed, it loses its orientation, and reverts back to traditional Aclar barrier properties,” he says.
FLEXIBILITY IS IN ORDER
Offered in 38-micron, 25-micron, and 18-micron gauges, Aclar Flex provides 1.5 to 2 times the moisture-vapor transmission rate (MTVR) value of other Aclar grades. “A 1.5-ml gauge (38-micron) Aclar Flex provides the same barrier as a 3-ml Ultrex 3000 Aclar,” van Weeren says.
Aclar Flex is among the clear barrier films that Amcor Flexibles (Mundelein, IL) is evaluating. “We are in tests with Aclar Flex to find out what we can do with it and how it might satisfy customer requirements,” says Bob Biasi, vice president, technology.
“We are looking at how we can put these clear barrier films in a lamination and meet customers’ requirements on performance and price. Many customers have difficulty telling us what their barrier requirements are. They usually say ‘it needs to be the same as what I am using today,’ which is foil. The clear barrier films tend to be more expensive than foil, but might provide an overall cost savings that you wouldn’t see with an opaque material” he says.
Aclar will gain usage in some applications as companies more precisely define their barrier requirements, agrees Haedt.
“Most medical device companies still prefer the absolute moisture and oxygen barrier properties that formable foil provides. As medical device customers begin finding it more acceptable to reduce moisture-barrier requirements, Aclar films will begin to take hold,” he says.
Oliver Medical is marketing Osurance, a zone-coated Tyvek, to companies that have not been willing to pay a premium for zone-coated lids. “We have automated our zone-coating process, eliminating five or six separate operations. Now we do it all in-line, so we are able to offer Osurance at a price comparable to a standard coated lid. We have had a lot of people interested who historically did not want to pay two or three times more for a zone-coated product,” says Murak.
Steam sterilization is also driving innovation in flexible packaging. Love from Tolas says that her firm has been working on steam-sterilizable barrier packaging to keep up with an increased interest in the sterilization method. “We are developing films and adhesives that will withstand 250 degree F in steam cycles of 30-45 minutes.” Current work is focused on rolled material for form-fill-seal operations.