Flexible Packaging: A Clean, Easy Transfer?
Despite the anticipated benefits of combining peelable films with new uncoated top webs, the materials are being adopted slowly and separately.
by Daphne Allen, Editor
|Tolas Health Care Packaging uses Tyvek 2FS for its Pouches on a Roll, which can be preprinted so users need only print lot codes and expiry dates.|
In 1999, new ground was broken in medical packaging. It appears, though, that little has followed the blueprints. DuPont Medical Packaging and a number of converters, including Rexam Medical Packaging, Perfecseal, Pechiney Plastic Packaging, Oliver Products, and Rollprint Packaging Products, almost in unison, all introduced new top and bottom web materials for form-fill-seal applications. These new materials promised to take significant costs out of medical packaging, while still maintaining the quality and performance of conventional materials.
A few years have passed since the introduction of DuPont's lower basis weight Tyvek, Tyvek 2FS, and films that incorporate a sealant layer for use with uncoated top webs (Rexam's Core-Peel, Perfecseal's CPT, Pechiney's DirectSeal, Oliver's PurePeel, and Rollprint's FlexForm T), and yet adoption of these materials appears to be slower than expected. These pioneers probably did expect a long implementation time, given the time it takes to validate new medical packaging. However, some concerns about the performance of Tyvek 2FS as well as the increased costs of the sealant films, also called peelable films, may have given pause to some device packagers. Whether or not these concerns are valid remains to be seen, but one reality has emerged: Device manufacturers have been inspired by these materials to drive costs out of their packages in unexpected ways. While the combination of Tyvek 2FS and sealant film may have yet to materialize, the materials individually are providing some economic benefits.
A WINNING COMBINATION?
Miray Pereira, global business manager for DuPont Medical Packaging, says that Tyvek 2FS was created to give users of medical-grade paper a more-competitively priced style of Tyvek. "We didn't expect to move a lot of customers from using Tyvek 1073B or Tyvek 1059B to Tyvek 2FS, because many devices need the higher performance features of Tyvek 1073B or 1059B," she explains. Uncoated Tyvek 2FS, when used with a film with a sealant layer for form-fill-seal applications, offers packagers a higher-performing alternative to coated paper and traditional films, she says.
Despite such intentions, however, converters and medical device manufacturers are discussing other uses for Tyvek 2FS. Converters such as Beacon Converters Inc. (Saddle Brook, NJ), Oliver Products (Grand Rapids, MI), and Perfecseal (Oshkosh, WI) offer pouches made with Tyvek 2FS and PET/PE.
And peelable film, the intended partner of Tyvek 2FS, is being used with other grades of uncoated Tyvek in pouch form. "We use one peelable film for our autoclavable pouches, and we use peelable sealants with various grades of uncoated Tyvek to offer cost savings over coated Tyvek," explains Brian Rosenburg of Technipaq Inc. (Crystal Lake, IL), a pouch manufacturer. "When you drop the coating on Tyvek 1073B or Tyvek 1059B and use a peelable film, you can realize considerable savings. We have had success with these films, and we are looking into new ways to convert Tyvek 2FS to offer improved seal quality with this style of film." Perfecseal offers a similar pouch using uncoated Tyvek 1073B with its CPT film.
Device manufacturers are finding other uses, too. One global medical device manufacturer in particular chose to use coated Tyvek 2FS in place of coated Tyvek 1073B for a form-fill-seal application. The firm was previously using Tyvek 1073B along with PETG, but wanted to reduce packaging costs. It needed a coated top web for sealing to the rigid PETG, and it found the performance of coated Tyvek 2FS to be nearly identical to that of coated Tyvek 1073B. As a result of this change, "we achieved a cost savings of 30–40%," says the firm's packaging manager. "Our product, a medium-sized device with no sharp edges, is more of a commodity, so we were interested in driving costs out of the package. A relatively minor change has led to significant savings."
This device manufacturer did evaluate coated Tyvek 2FS for another form-fill-seal application, but ran into some complications. "When we cut into the seal area, which our form-fill-machine often did because of machine drift, we saw a much higher level of delamination than with other styles of Tyvek," explains the packaging manager. "To avoid that we would have had to retool our machine, and for this product line the savings weren't significant enough to justify the effort. Knowing this, if we see a cost benefit to other Tyvek 2FS uses, we will design our packaging differently so the seal area is not close to the package edge."
Another device manufacturer recently converted a large portion of its coated pouches from coated Tyvek 1073B to uncoated Tyvek 1059B. "This provided us with a material cost savings with little or no loss in functional performance," explains the firm's lead packaging engineer. "This program was also driven by our desire to reduce EtO sterilization cycle times and the compatibility of uncoated Tyvek to coincide with that process change." His firm chose to continue using standard PET/PE film, where LDPE is the sealant layer. "Although I am intrigued by the aesthetics and performance of clean peel films, I have been unable to justify evaluating them because they do not offer a cost savings versus what I am currently using."
This same packager did evaluate Tyvek 2FS for replacing Tyvek 1073B, but chose Tyvek 1059B instead. "We evaluated uncoated Tyvek 2FS, but we were disappointed in its bonding and seal strength values to other substrates, due primarily to its thin nature. It does seem to perform better when coated. Uncoated Tyvek 1059 has a history of success, however, making it an easier transition. We have not had many complaints or problems with fiber tear with the uncoated Tyvek 1059B."
Finally, a third medical device manufacturer uses uncoated Tyvek 1073B for nearly all its pouches, coupling it with a standard PET/PE lamination. "We have found Tyvek 1073B to be stronger than Tyvek 2FS, and the cost difference is minimal," explains the firm's packaging engineer. "We haven't had any complaints about fiber tear, but when you open the pouches aggressively, you do see fibers. Peel consistency is fine, but the uncoated Tyvek doesn't produce as visually nice a peel transfer as a coated one."
These are only the anonymous stories of three, hardly a significant sampling of thousands of medical device manufacturers. However, just like their peers, these three firms strove to reduce packaging costs, in these instances evaluating uncoated Tyvek 2FS or peelable film to some degree and tailoring them to meet the requirements of their products and processes. Their outcomes were also largely dependent upon the products and prices their converters offered.
But their experiences may prompt the same questions currently being asked in industry by others: Does uncoated Tyvek 2FS perform as well as other medical grades of Tyvek? Are the peelable films too costly to implement, and perhaps unnecessary, given success without them?
William Singer, Perfecseal's vice president of marketing, isn't surprised by these questions, stating that there is a lot of confusion about Tyvek 2FS and peelable films. To help users work with the newer materials, Singer says that his firm and other converters have been working closely with DuPont to ensure that the newer films and Tyvek work well together.
Pechiney has also seen slow acceptance of the films, particularly to uncoated Tyvek 2FS. "There has been more acceptance with uncoated Tyvek 1073B," says Lynn Allen, medical product manager. "Our customers are balancing their standards for fiber-free peel and specified seal strengths with lowering overall product cost."
DuPont's Pereira explains that medical device manufacturers need to account for the unique characteristics of Tyvek 2FS when evaluating the material. "Tyvek 2FS is thinner than Tyvek 1073B or Tyvek 1059B, so it is designed for items that don't need as high a package strength." Because it is thinner, users must tailor their sealing parameters so that they accommodate this lower basis weight material. "By using the appropriate temperature windows and carefully controlling other parameters, you can avoid overheating, which can cause Tyvek 2FS to melt." This is important, she says, because such melting can contribute to fiber tear when films are peeled from Tyvek 2FS.
In addition, Tyvek 2FS is manufactured differently than Tyvek 1073B or Tyvek 1059B, Pereira says, and as a result its rough side is stronger than its smooth side. To help users tell the difference between the two sides, DuPont included a section on sealing to the proper side of Tyvek 2FS in its recently published Technical Reference Guide for Medical Packaging. "If you seal to the smooth side of Tyvek 2FS, you will see fiber tears when opening sealed packages," she explains.
To counter concerns about delamination, Tiromat Medical Packaging (Frisco, TX) has a proprietary sealing tool design that appears to lessen delamination upon opening. "This design has been used successfully in direct seal paper applications in Europe and Asia for some time, but its potential for uncoated Tyvek 2FS is just now being fully explored," says managing director John Merritt. "We are quite encouraged by initial results, and more work is planned to confirm the benefits of the design."
Regarding concerns about the cost of peelable films, both Perfecseal and Rexam (Mundelein, IL) admit that their CPT and Core-Peel films, respectively, are more expensive than conventional poly films. For instance, Rexam's product director for coated and laminated products, Bob Liesenfelt, says it costs about 20% more than the cost of traditional poly films to add a sealant layer to them. For Core-Peel, Rexam currently adhesive mounts the sealant layer to the device manufacturer's choice of substrate. An investment in equipment and the advancement of the Core-Peel technology will enable Rexam to offer coextruded laminations and blown-film versions.
For a fair comparison, Liesenfelt says costs of the total process should be considered. "Not only have you reduced the cost of your top web by using an uncoated Tyvek, but you also take the worry out of using that uncoated top web. You have a sealant layer that ensures a fiber-free peel."
In addition, because sealant films have a wider sealing-temperature window, packagers can run form-fill-seal lines faster. For instance, "if the target sealing temperature is 250°F, and a firm wants to speed up its line, it can do so by raising the temperature to 300°F and not see a difference in package performance," says Liesenfelt. An increase in speed increases throughput, which can reduce costs.
Liesenfelt and Singer also point out some distinct benefits to using the combination of uncoated Tyvek 2FS and peelable film, or at least either of its components. "You can cleanly peel sealant films from Tyvek 2FS and other styles of Tyvek, and you can clearly see the seal transfer," says Singer. "With PET/PE film and uncoated Tyvek, say for a pouch, the seal transfer is not as dramatic. You can get a clean peel, but just not the transfer."
Because an opacifier has been added to Tyvek 2FS, it is whiter and has a much more uniform look. As a result, Tyvek 2FS offers "printing enhancements," says Singer. "It's good for heavy graphics and type."
COATING'S KNOCKOUT PUNCH?
When this combination or either of its elements does take off, will demand for coated top webs married to flexible bottom webs drop considerably?
Carl Marotta, president of Tolas Health Care Packaging Products (Feasterville, PA), acknowledges that Tyvek 2FS and peelable films do offer savings benefits when compared with coated Tyvek and traditional films and that they may end up being the most attractive for some applications. However, he says that coated materials are more versatile; they can be sealed to just about any plastic, and there is less of a tendency for seals to fail, especially during sterilization and distribution.
Aware that manufacturers need materials that lower costs, Marotta says that Tolas developed a series of coatings that could speed up form-fill-seal lines. TPT0231A, TPT0237A, and TPT0268, for Tyvek 1073B, Tyvek 1059B, and Tyvek 2FS, respectively, feature high hot tack and a wide seal temperature range so device packagers can seal at lower temperatures and higher speeds, translating into overall process savings. Tolas also introduced a PET/PE film with a thin coating to perform similarly to peelable films for use with coated or uncoated Tyvek or paper.
Oliver Products applies hot-melt adhesives to Tyvek in a dot pattern that results in a porosity approaching that of uncoated Tyvek. "Savings from the dot coating are being realized by customers who have been able to decrease sterilization cycle times significantly," says Jeff Murak, director of sales and marketing. "It offers all the benefits of uncoated Tyvek, including cost savings, while still guaranteeing the fiber-free consistency that comes with adhesive coatings."
Ultimately, Marotta understands that device makers must balance price with value, and for some that means choosing an uncoated material. However, when basing selections primarily on cost, he advises, "Make sure you don't wind up paying more through waste and inefficiencies."