Breaking Into Medical Films

Over the past year and a half, several major producers of high-tech, highly layered flexible films for barrier food wrap have qualified their first coextruded films for medical packaging. Most of the food-film companies already had small medical film operations and had tried for years to apply their low-cost production, economies of scale, and experience with highly layered structures to the medical market. Now they’re becoming factors to reckon with in this high-priced specialty business.

Medical packaging film is said to be growing at 2% to 4% per year, about the same as food packaging but faster than the economy as a whole. Medical packaging is also seen as a secure business. “Once you’re in, you’re in,” explains an executive of a big provider of healthcare packaging.Changing vendors would require the device maker to requalify its product with the FDA. “Unless you do something bad, you’re unlikely to lose the business.”

Requirements for medical packaging are very different from those for food wraps. Flexible food packages have to provide tight oxygen barrier to preserve processed meats and cheese. Extruded films for medical packages—mostly forming films and sterilizable protective bags for medical devices and hospital supplies—have to provide a microbial barrier, resist puncture, and survive sterilization.

What the food film companies bring to the table is expertise in highly layered structures. Coextrusion cuts cost in several ways. It can replace expensive materials and use resins more efficiently. It can also in some cases reduce the number of production steps by eliminating coating or laminating. Highly layered medical forming films can have a structure of PE-tie-nylon-tie-PE-tie-nylon-tie-PE, or the same structure might substitute PP for nylon. They can be 2 to 16 mils thick. Most are 6 to 9 mils. In these films, nylon is used only for puncture strength. No EVOH is used in medical packaging because no oxygen barrier is needed.

 

Making films sterilizable

The two most common methods of sterilization are ethylene oxide gas and radiation. The breathable part of a package, often medical paper or DuPont’s Tyvek nonwoven fabric, lets the ethylene oxide in and out. (High-temperature autoclave, steam, or hydrogen peroxide plasma are also used for in-hospital sterilization, but don’t apply to most packaging.)

Up to now, thermoforming films for the bottom web of a device package typically have been three-layer coextrusions of EVA-ionomer-EVA or ionomer surrounded by layers of EVA/PE blend. Ionomer is tough and clear, but expensive. If a heavier gauge forming or bag film were needed, a three-layer EVA/ionomer blown film was often collapsed on itself to make six layers. 

Top lidding is typically a paper/plastic/foil combination produced by extrusion coating and laminating. This lidding web provides specific opening characteristics. For example, syringes for ambulance and emergency-room use must pop out fast. Other lids must peel open slowly.

Sterilizable bags are clear pouches that open with a linear tear at one end. Bags are also typically three-layer structures of EVA and ionomer. The ionomer provides the linear-tear feature. If gas sterilization is used, most bags will have a breathable patch or header strip made of Tyvek or paper. A bag with a header strip doesn’t require linear tear, so a monolayer LLDPE or multi-layer olefin film can be used.

In the past two to three years, nylon slowly has been replacing ionomer in forming films as a way to reduce packaging cost. The number of layers goes up automatically since nylon requires a tie layer to stick to the PE seal layer. Three years ago, Rexam Healthcare Flexibles in Mundelein, Ill., installed the first of two five-layer blown film lines, along with a five-layer lab line to develop new coex forming films based on nylon. Its first five-layer, nylon-based film was introduced in 2001. That film offers customers the option to downgauge—for example, from a 12-mil, three-layer film with ionomer to a 10-mil, five-layer film with nylon.

 

Layers set new records

In the past 18 months, the number of layers in such films has burgeoned, as several companies have qualified the first eight-, nine-, and 11-layer films for medical applications. Such highly layered films are still only a small factor in the market, but they’re driving down the cost of packaging for some commodity medical products like glove packaging, where the package usually costs more than the product it contains. Such novelties are shaking up what has been a clubby, conservative market that resists change.

Several food-packaging giants are the main ones responsible for introducing these many-layered films. Winpak Ltd. in Winnipeg, Manitoba, qualified its first medical packaging film in North America, a nylon-based structure with 11 layers for making sterilizable bags. This is probably the most highly layered coex film in medical packaging anywhere in the world. Winpak won’t identify its structure, but the film is made on an 11-extruder cast film line originally used for barrier films for thermoformed food packaging.

More recently, Winpak has qualified highly layered blown films for medical packaging that are made on lines with eight and nine extruders in its Senoia, Ga., plant.

“We have created some interesting new options,” says David Johns, president of Winpak’s packaging division in Winnipeg. Winpak’s goal is to expand its medical business by applying technologies from coex barrier food packaging to reduce the cost of medical forming films. “We’ve worked behind the scenes for three years to qualify several applications and are being evaluated for several others, using some of the new-generation materials like metallocenes to provide savings. We have found that medical markets are open to looking at new things. The medical market will become as competitive as other packaging markets,” he predicts.

Winpak has a sister company based in Finland called Wipak, a major global producer of high-tech packaging films. Wipak’s medical film expertise in Europe helped obtain validations for the new structures from North American regulators, says Heikki Weijo, managing director of medical packaging for Wihuri Oy Wipak in Nastola, Finland. In 1997, Wipak installed a special cast film line in the European equivalent of a Class-100,000 clean room (100,000 particles per cu ft of air), giving it the first clean-room production of medical-device packaging film in the world, Weijo says.

Winpak wasn’t the first to transfer high-barrier technology from food-packaging films over to medical applications. Bemis Co. in Minneapolis had the same strategy in 1996 when it combined its relatively small medical film business with its acquisition of Perfecseal, a paper coating and converting operation. The combination created a larger medical packaging venture that introduced to the market lower cost, highly layered medical forming films developed by Bemis’ Curwood food-packaging division.

“Multi-layer has been our foothold over the last seven years,” says Chris Osborn, rollstock marketing manager at Perfecseal. “Now you’re seeing big changes in customers’ willingness to look at multi-layer materials. We’re seeing a lot of growth in coextruded films. Films that use thin discrete layers allow for more efficient use of expensive high-performance polymers.” Perfecseal this year opened its first dedicated plant for medical films in New London, Wis., consolidating medical production previously scattered over several food-film plants. At New London, Perfecseal makes blown films with “well over five layers,” Osborn says.

Pliant Corp. in Chicago, which has supplied both food and medical packaging films for years, also began its first production of seven-layer medical films just 18 months ago. “It’s a development we are expanding to offer some innovative products to the market,” says Ken Swanson, senior v.p. and general manager of specialty films.

Most recently Amcor Ltd. in Melbourne, Australia, announced its intention to acquire Rexam Healthcare Flexibles. The deal, expected to close last month, could eventually result in the same crossover of highly layered film technology from food to medical packaging. “Amcor has the barrier capability and size to bring those changes to Rexam,” says a consultant to the North American packaging industry. For example, he notes, Amcor has seven- and nine-layer barrier-film technology at its Auckland, New Zealand, operation.

“We know of several other food-packaging companies that intend to get into medical because they think it has higher margins,” says Christof Herschbach, marketing manager of Windmoeller & Hoelscher in Germany. In the last six months, Macro Engineering & Technology in Mississauga, Ont., sold three 2.5-meter lines to make coex cast films for medical and food packaging films. These lines have seven- and nine-layer dies and nine or 10 extruders. Two lines went to China and one to Brazil.

 

Blown vs. cast

North American medical packaging films are mostly blown film. This process is preferred for the forming films because of its inherent orientation and greater tear strength. However, some blown film lines originally designed for food packaging present challenges to use in the medical-film arena. High-output, water-quenched, downward-extruded bubbles may require different nylon formulations for medical use because an amorphous film often has more memory and shrinkage around the product being packaged. That can be a disadvantage if it is a sharp or fragile medical device.

In Europe, cast film is preferred for extruded medical films because it has better gauge control. Cast film also allows controlled morphology, so films can be made very amorphous for a softer feel than blown film. “In the U.S. it’s still up in the air which process will dominate,” says the technical director of one large U.S. healthcare company that coextrudes some of its own medical films. Adds Steve Post, manager of cast film business at Davis-Standard Film & Coating Systems in Somerville, N.J., “Highly layered cast medical films aren’t produced on conventional equipment. Moisturization in a water tank and annealing rolls are often required to make flat film.”

 

Responding to competition

Established medical film companies are inherently vulnerable to the new high-tech competition from food packaging makers. Investing in new technology is not as easy for traditional medical film makers, who also have less incentive to do so. Once a medical packaging film is approved, the processor isn’t allowed to change or upgrade the extrusion line in any way without customer approval. Thus, many medical packaging films for long-running products are made with older equipment and technology.

Food-packaging equipment, on the other hand, is upgraded continually. Coex food-packaging lines also typically use more advanced instrumentation to verify and control film thickness and barrier properties. Perfecseal’s new film plant in Wisconsin monitors and controls caliper automatically on coex cast and blown film lines. In contrast, most medical film makers rely on gravimetric feeders and off-line film sampling for layer and gauge control. “The medical film market has not been active in on-line layer measurements,” says a product manager at EGS Gauging Inc. in Billerica, Mass., which makes FSIR (full spectrum infrared) systems for individual layer detection. “All the multi-layer food films use it,” this source says.

Established makers of medical films reply that they are indeed investing in quality control—though perhaps more in quality management than in technology. Despite the pending sale to Amcor, Rexam Healthcare Flexibles is seeking to certify all its North American plants by early 2004 according to the ISO 13485 quality standard (based on ISO 9001) for makers of medical devices. Rexam executives believe this will be an industry first. Rollprint Packaging Products Inc., a supplier of extrusion coated and laminated medical films in Addison Ill., already claims on its website to comply with ISO 13485, but hasn’t obtained formal certification.

Rexam is also responding to the new competition by increasing output through methods that don’t require revalidation of its process. “Over the last three years, we’ve increased film output at least 20% to 30%,” says Michael Oberkirch, director of marketing for Rexam Healthcare Flexibles in Mundelein, Ill. “We’re pushing to make film better and faster.”

One smaller film laminator has responded to competition by installing coex coating operations. In 1999, Rollprint invested $14 million in coextrusion coating equipment with three extruders and a fourth for edge encapsulation, designed to deposit one to five layers on top of film, paper, foil or other substrates. “We put in the coex coating equipment to provide improved quality and performance and reduce cost,” says Rollprint president Robert Dodrill. “We had to do it to survive and grow.” Rollprint makes a unique five-layer, coex polyester/foil composite to package iodine swabs.

Rexam is also cutting costs through coextrusion coating. A peel able product called Core-Peel was initially made of multi-layer coex blown film that was adhesive laminated onto an oriented film substrate. Rexam now makes the product via coextrusion coating in a single pass, which results in a less expensive, more robust film.

 

Resisting change

A lot of factors inhibit change in the medical film business, from the slow approval process to a culture of long-standing business relationships. Medical device makers typically prefer to deal with long-time suppliers and familiar materials, regardless of cost, say medical film processors. “Medical packaging business is awarded based on who you know,” says the president of an extrusion equipment supplier. “It’s a network. It’s like a club.”

Medical packaging films can be registered for use with a specific medical device by the Food & Drug Administration, a process that can take several years or longer. Generally, however, the FDA regulates medical devices, but leaves the choice of acceptable packaging largely up to the device makers. The FDA doesn’t approve films as independent products.

Films are validated for medical use by the device maker. The validation stipulates—and essentially freezes—every aspect of production, including exact resin grades and additives, extrusion parameters, and even which specific extruder in a plant makes the film.

Once a package is qualified, production can remain unchanged for years. Nothing can be changed without notifying the device maker. A change is made only if the purchaser sees enough cost advantage to justify going through the expense of requalification. Whether the device maker notifies the FDA of the change depends on the corporate practices of the device maker and how critical the device is.

This relatively inflexible system means that a medical film processor must be assured of a stable, long-term supply of approved resins. If a resin company stops producing one of those materials, the whole film has to be requalified with a new resin. Because additive migration under various sterilization conditions is a big issue with resin selection, the new resin would have to go through extensive revalidation testing.

Once it’s approved, it’s uncommon for medical-film processors to tweak a product to shave pennies off its cost. “Device makers wouldn’t consider a packaging change unless it was going to save them hundreds of thousands of dollars a year,” says a medical packaging supplier. “They won’t take a package that costs 45¢ and work to get it down to 42¢, when the device they’re putting inside may cost $4500.” However, medical-device suppliers are feeling pressure from large hospital purchasing groups to cut costs of more commodity-type packaging of large-volume items like gauze, syringes, tubes, and swabs.