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PLA film shrinks to fit
January 29, 2014
8 Min Read
Farmingdale, NY-based label converter Seal-It, Inc. (www.sealitinc.com) is on the “husk,” as it were, of an exciting new advancement in the shrink-film label market. Since February, Seal-It has been offering its customers shrink-sleeve labels made from a film based on renewable resources that has proven to be competitive in both characteristics and cost with most traditional, petroleum-based films.
The transverse-direction-oriented (TDO) polymer, called EarthFirst® PLA TDO, is made from a corn-based polylactide resin, NatureWorks® PLA, engineered by NatureWorks LLC (www.natureworksllc.com). The result of considerable research and development by film manufacturer Plastic Suppliers, Inc. (www.plasticsuppliers.com), EarthFirst PLA TDO is the first commercially viable shrink film made from NatureWorks PLA to enter the market.
“I really believe that this is the film of the future,” says Seal-It president Sharon Lobel. “While we shouldn’t disregard the other films, because they all have their place depending upon the application, PLA is the new kid on the block now, and everybody wants to get to market with it first.”
NatureWorks PLA was first introduced in 2000 and, since then, it has slowly but steadily spread across consumer packaged goods applications, from thermoformed deli containers and film lidding to disposable tableware and beverage bottles, and from Europe to the U.S. The technology used to produce the resin involves harvesting the starch stored in natural plant sugars. This sugar is then fermented into lactic acid, which is used to create a clear plastic, or PLA, that can be used for a variety of packaging formats.
Initially, one of the barriers to adoption of PLA was its high price relative to existing, petroleum-based films. In 2002, NatureWorks LLC, then Cargill Dow, christened its first large-scale production facility in Blair, NE, for the manufacture of PLA, with an estimated output of 300,000 million lb of resin per year—half of which was slated for packaging applications (NatureWorks LLC’s Ingeo™ fibers for textiles are also made from PLA). This increased production capacity, coupled with a petroleum market besieged by volatile pricing, helped to bring the cost down to a more palatable level for potential customers.
Says Rich Eichfeld, vp of business development for Plastic Suppliers, “We first manufactured PLA film on May 5, 2004. We had considered using it prior to that, but it was too costly. Once NatureWorks LLC’s manufacturing methods gained economies of scale, it became more feasible for us.”
A perfect fit for Plastic Suppliers—a producer of biaxially oriented polystyrene—PLA lends itself very well to the company’s existing manufacturing processes, Eichfeld says. At its plant in Columbus, OH, Plastic Suppliers has engineered EarthFirst PLA film for a variety of packaging applications, including folding-carton windows, bag windows, bag laminations, container lidding, twist wraps and floral wraps, as well as shrink film.
As Eichfeld relates, the biggest challenge to adapting PLA film for these applications has been the rigidity of the film. “One-hundred percent PLA has limitations,” he explains. “It’s a very brittle product. The way we addressed this problem was through different additives and manufacturing processes.”
It took Plastic Suppliers about one year to engineer a PLA film suitable for shrink-sleeve label use. To develop the film, Eichfeld says the company drew upon its expertise in the manufacture of its Polyflex® TMOPS preferentially oriented PS shrink film, as well as on input from co-branding partners like Seal-It. “Through communication, we were able to make proper adjustments to the film to meet Seal-It’s concerns,” he says. “Then we would allow them to look at the film and give us their feedback, and we kept refining as we went along. Seal-It was instrumental in helping us to introduce this product to the market.”
Operating two, side-by-side facilities totaling 150,000 sq ft of combined manufacturing space, Seal-It has provided label printing and converting services for 20 years. With a focus on heat-shrinkable label applications, the company works with a variety of substrates, including polyvinyl chloride, polyethylene terephthalate glycol and OPS to produce full-body shrink-sleeve labels, tamper-evident neckbands, multipack wrappers and more.
The company’s services include in-house design and prepress, as well as modified flexo printing, gravure printing and label seaming. Seal-It’s newest equipment is a 40-in., 10-color gravure press from a proprietary supplier.
Upon Plastic Suppliers’ invitation, Seal-It tested the EarthFirst PLA TDO film on its converting equipment during the material’s development phase. “We’ve been fortunate that we’ve been able to work with the film and learn how to handle it on our equipment,” says Lobel. “Some other converters may just be starting now; it will take them a while to learn how it handles. Even though the final product looks pretty much the same [as labels made with petroleum-based films], the converting and handling of the film is very different. It takes time to learn how to work with PLA.”
EarthFirst PLA TDO, available in 2- and 2.4-mil thicknesses, is scuff-resistant, compliant to U.S. Food and Drug Administration standards and offers up to a 75 percent shrink in the transverse direction. According to Lobel, only PETG has a higher shrink rate—at 80 percent. “But the seventy-five percent of shrink that PLA offers will accommodate 99.9 percent of the applications that are out there,” she adds.
For shrink-sleeve applications, Eichfeld relates that PLA’s inherent brittleness is somewhat of an asset, allowing it to shrink easily onto a package. However, because it has a lower heat tolerance than other label films, users need to program their shrink tunnels to run cooler than usual.
As for printability, EarthFirst PLA TDO is said to be compatible with all traditional printing processes, as long as converters learn how to adjust their tension controls to accommodate the new material.
As Lobel explains, part of Seal-It’s learning curve with the new film was to test it on every piece of equipment necessary to produce a shrink-film label. “We took it every step of the way,” she says. “We had to look at the printability to make sure that the colors were vivid and bright. We looked at our slitting equipment and said, 'If this is how we slit films that we already work with, how do we have to change the process to accommodate PLA? Do we need different blades? Do we need different equipment?’ We looked at the seaming process to see if there were any differences there, and so on.”
As for the issue of cost, PLA is now gaining a favorable footing because of the stability of maize prices versus petroleum-based polymers such as PET. In late 2005, NatureWorks LLC reported that its PLA product had been price-competitive for the previous 16 months with PET, and in some cases, it was even cost-advantaged over PET.
Says Eichfeld, “It’s not the least-expensive product on the market; that would be PVC. But PLA can compete with most shrink films.”
Concurs Lobel: “The cost for PLA is better now than it used to be. It’s still more than PVC, but after [Hurricane] Katrina, even the cost of PVC has gone up. If you rate the cost of the four films—PVC, PLA, PETG and OPS—I’d put PLA somewhere in the middle.”
Machinability and cost considerations aside, PLA’s desirability also lies in its natural, renewable origins. In January, with the purchase of Renewable Energy Certificates (RECs), NatureWorks PLA became the first and only greenhouse-gas-neutral polymer on the market. The RECs serve as an offset to cover all of the emissions from the energy used for the production of NatureWorks PLA—from the fuel farmers use in their tractors to the final production of the polymer. NatureWorks PLA also uses 60- to 70-percent less fossil fuel resources than traditional plastics, reports NatureWorks LLC.
Another benefit of the resin is that products made from NatureWorks PLA can be disposed of through composting.
While Seal-It cannot yet disclose any of its customers pioneering the use of shrink-film labels made from EarthFirst PLA TDO, Lobel says that “everybody wants to do it first,” especially the larger customers. Eichfeld agrees, noting that in the last three months, the increase in interest in the product has been “dramatic.”
“The interest level has increased one-hundred-fold,” he says, attributing it to Wal-Mart’s launch late last year of a sustainable packaging initiative that included a goal of converting an estimated 114 million PET containers to NatureWorks PLA.
Lobel says that while stores such as Wal-Mart have given PLA a big push, that was not the driver behind Seal-It’s adoption of the material. She relates that “it’s exciting to offer a film that has no dependency on oil and is totally home-grown.”
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