The Right Stuff for Bags and Pouches
Choosing the right materials and following an adequate design process are essential to the development of bags and pouches that meet application- specific requirements.
by Erik Swain, Senior Editor
Rollprint produces peelable chevron pouches for EtO, gamma, and autoclave sterilization using its tamper-evident seal technology.
In an effort to help device manufacturers, bag and pouch suppliers offer time-tested systems for determining whether or not a premade bag or pouch is the best solution, which materials are appropriate for the specific application, and how the package can be designed around the product.
THE PACKAGING PROCESS
In their search for the right packaging process, device manufacturers will need to find the answers to several questions, including, "Will the product lend itself to form-fill-seal automation?" According to Scott Keller, director of sales for KenPak (City of Commerce, CA and Marshall, NC), div. of Pechiney Plastic Packaging (Chicago), device manufacturers must first choose "a packaging method that will maintain the sterility of a package, and then, consider economics."
Phil Rosenburg, president of Technipaq (Crystal Lake, IL), notes that "Many medical device manufacturers will try to transfer their packaging over to rollstock for one reason or another. Everyone is trying to alleviate hand labor, but a lot of times the product doesn't allow it. For example, if you're dealing with a four-part kit, that would not be simplistic to adapt. If it's a bulky device, automation may not be feasible and you have to hand fill."
"Form-fill-seal machinery means up-front capital expenditures and a trained labor force to operate the equipment," explains Keller. He points out that the volume of medical devices produced may not be enough to justify the purchase of form-fill-seal equipment. "Also, in many cases, device packaging operations must be in a centralized location to justify purchasing costs."
Rexam's patented Core-Peel technology separates the peel and seal functions into two layers.
If form-fill-seal automation is not feasible and the device is not so cumbersome as to require a more expensive rigid tray, the premade bag or pouch often becomes the recommended solution. From there, it must be determined what kind of protection the device needs without overcompensating and adding unnecessary cost. Keller notes, "bags and pouches can be purchased out of stocking programs, and they allow for packaging of the product from multiple locations."
As a starting point, Leslie Love, national sales manager at Tolas Health Care Packaging (Feasterville, PA), recommends that device manufacturers find out which sterilization process the customer intends to use. If the customer will be using EtO or autoclave sterilization methods, a breathable structure must be used, says Love. "We go down the list from there and try to get as much information as possible. What chemicals will the package be subjected to? Are there any requirements for moisture or oxygen barrier? Is puncture resistance needed? A high-profile or sharp product has a tendency to poke through a package, so we would have to select a material with better puncture resistance in that case."
If a breathable structure is needed, a porous material such as a medical-grade paper from Kimberly-Clark Corp. (Roswell, GA) or Tyvek from DuPont Medical Packaging (Wilmington, DE) is required. Kathleen Daly Mascolo, vice president and director of sales and marketing, Beacon Converters (Saddle Brook, NJ), says that paper can be the right material choice for devices that are lightweight and just need a basic sterility barrier. However, "if there is any kind of development where you need a better presentation, you have to use Tyvek. Tyvek 2FS, a thinner Tyvek for lighter-weight devices, is making a place for itself with those who would normally use paper, or who always liked Tyvek but considered it too expensive for a light device," says Daly Mascolo.
One increasing design concern is what to do for materials that need barrier protection as well as breathability during sterilization. A number of suppliers offer a foil or film pouch with a Tyvek header strip. "After you sterilize, you seal over the header strip and cut the strip off, so you have a foil-to-foil pouch when you go to market," Daly Mascolo says.
High-barrier foil header pouches from Rexam provide protection for moisture- and oxygen-sensitive medical devices.
For pouches where fiber tear is a concern, coated Tyvek variants are available to minimize fiber tear, says Darryl B. Goodwin, product manager— films and converted products for Rexam Medical Packaging Inc. (Mundelein, IL). Another option, he says, is PET laminates with special seal and peel layers for use with uncoated Tyvek. "The added benefit of these layers is a visible seal transfer, which gives a visible indication of seal integrity."
The most common structure, suppliers say, is uncoated Tyvek 1073B or Tyvek 1059B sealed to a 48-gauge polyester laminated with 2 mil-polyethylene, which provides puncture resistance, strength, and a sterility barrier. However, says Daly Mascolo, these structures don't offer "anything extra like moisture barriers. For that you may need foils. First you can see if a metallized structure would work, but foil provides an even higher barrier. For even more barrier, you can increase the thickness of the foil."
Goodwin notes that nonfoil high-barrier laminates, which would offer increased barrier with the added benefit of clarity and visibility of the device, are in development.
For extra puncture resistance, suppliers often turn to nylon or other materials. Fortunately, Daly Mascolo says, "there are a lot of films available that seal to and peel from uncoated Tyvek. There have been developments with nylons that are giving device manufacturers more of an opportunity to stay in a pouch before they have to go to a tray."
This means that getting the proper sealant is crucial. Significant progress has been made in heat-seal coatings, says Craig Livingston, vice president of sales for Rollprint Packaging Products Inc. (Addison, IL). "With our different peelable sealants, you can have as wide an operating window as you need because we can adjust the seal strength based on the sealant chemistry," he says. "One of our peelable extrusion coatings is designed to peel at the same amount of peel force whether sealed at 275° or 400°F."
In addition, suppliers have tools for helping customers with material selection. Love says, "we provide data sheets that point out the various pluses and minuses of each potential structure, and show a copy of our ISO 11607 file for a particular material. These contain information about age studies, toxicity issues and the like, and may alleviate the upfront selection process."
Cost considerations come into play once it has been determined what properties the package needs. Love explains that cost is an important consideration when choosing a package for a less expensive product.
Jeff Murak, director of marketing and sales, Oliver Products Co. (Grand Rapids, MI) says, "Some people want to move up the scale into tougher material, or have more peace of mind in a stronger material." Murak explains that the baseline of what they can use for a particular product is suggested, but the final decision rests with the customer.
New material blends are helping reduce costs. Livingston says, "In the past, it was about reducing the gauge of existing films. Now along with material gauge reduction, we're running numerous resin blends, utilizing metallocenes and other new resins to eliminate higher costs while keeping the physical properties of the films the same or better than what our customers were using."
Chemical resistance for film and foil structures is also an important cost consideration. "Extruding multiple layers, including polyester, allows for a high chemical resistance," Livingston says. "We have equipment that allows us to extrude five different materials in one pass. That provides a major cost-benefit."
THE DESIGN PROCESS
The customer and supplier need to work through all of the materials' dimensions and tolerances together. Some materials force certain design choices, Love says. "For certain materials, because of curl, we put a tack on the chevron end, as opposed to an end gap."
If the pouch is to be printed on, even the placement of the artwork must be thoroughly considered. "We ask for the copy to be laid out in a way to avoid printing in the seal area," Love says. "If it's easily avoidable, this eliminates the potential for ink pickoff during sealing processes. Printing requirements and artwork should be reviewed for font style, type size, screens, and color requirements, taking into consideration the packaging material being printed."
Medical bags and pouches are available in a wide variety of configurations, but it takes close collaboration between customer and supplier to determine the correct one for a particular device. And the right decision will yield a protective, economical packaging solution.