Extending Their Reach:

With improved technology, applications for films multiply

By Noel Jeffrey

Toray's printable LumiLid® XLS5 is a polyester high-barrier lidding film.

Packaging films are everywhere. They are variously called BOPP, HDPE, LDPE, MDPE, OPP, PET, Polyester, Polyethylene, Polypropylene, and more depending on their chemical characteristics. Product categories from food to pharmaceuticals use one of more of these for some of its packaging. Consequently, continued developments in film manufacturing, the associated chemistry, and the inks used for printing on film offer brand owners and their designers new ways to attract and serve consumers.

Michelle R. Hearn, director of marketing, Sun Chemical North American Packaging, says, "We see food safety, convenience, and extended shelf life as major drivers in food packaging today."

Filmmakers are responding. For instance, Honeywell Specialty Films recently introduced a new product, called OxyShield Plus, a mid-level oxygen-barrier Nylon/EVOH/ Nylon biaxially oriented film. According to the company, it has outstanding resistance to solvents, oils, and greases. The product also offers superior mechanical properties, good transparency and gloss, easy printing and lamination, and resistance to flex cracking.

Consumer market drivers

With newer films like Honeywell's line and others, replacement of traditional paper bags, boxes, and cans as a response to those drivers continues. Sharon Derbyshire, principal of Contract Market Research in Cary, NC, predicts further progress in flexible packaging for pet foods and canned consumer foods.

"Semi-moist treats in stand up pouches were introduced some 10 years ago for pets. Now, canned wet foods in retort pouches are established," Derbyshire says. "What's new is that we are going to see large format flexible packaging replace multiwall paper bags. It used to be that flexible packaging was used for bags under 10 lbs. and paper for those above 10 lbs. Now suppliers have developed larger format bags with zippers and handles—features that consumers desire but are more difficult to incorporate into a multiwall paper bag."

She notes that it is consumer perception that metal cans are safer than pouches that has slowed adoption in the United States. "Japan and the rest of Asia have fruits and vegetables in pouches. Europe is somewhere in between the U.S. and Asia," she says. Derbyshire also points out that products in pouches are superior in quality to canned because during the retort process food must be heated to a certain temperature in the center. That temperature can be reached sooner in a flat pouch than in a metal can. Consequently, consumers get a premium product from a taste, texture and nutritional standpoint because it doesn't degrade as much.

Derbyshire also says that offering visibility is an important development. "Partially printed pouches using windows offer increased shelf value. Personally, I'd rather be able to see, for example, the color and size of diced tomatoes," she says. "The technology is developing to offer clear coextruded pouches for retort applications."

Transparent film is for more than food. Ampac Flexibles, a unit of Ampac Packaging LLC in Cincinnati, has introduced a new clear high-moisture (MVTR) barrier lidstock that can seal to trays, cups, etc., made from a wide variety of plastic materials. The company says that Flexi-Free 6985, the first high MVTR lidstock without a foil layer, is targeted for cosmetics, health and beauty aids, nutraceuticals, medical devices, etc.

Digital printing also is getting attention. Innovia Films has developed a range of approved HP Indigo substrates to support short run digital printing using HP's WS2000, 4050, and 4500 liquid toner presses. Liquid toner industrial printing requires special dedicated top coated films for optimum performance and quality; dry toner systems can work, with care, with standard coated films.

Ampac's Flexi-Free® 6985 is high-MVTR lid stock.

Suppliers' perspective

Sun Chemical's Hearn also points out that films developed for the shrink wrap market are getting more and more complex and sophisticated, even though basic raw materials remain the same—PVC, PET, and OPS.

All of these developments challenge ink makers. Hearn says, "The choice of film, design of packaging structure, and the application requirements all greatly influence the properties needed in the ink system used. For example, an ink that is used in a multi-layered lamination structure needs different properties than an ink designed for printing on the surface of a film. Sun Chemical has a wide range of ink products for different packaging structures and applications."

The reason shrink applications are more complex and why the inks need to have higher performance characteristics is related to the degree of shrinkage and the choice of substrates. "If a film is required to demonstrate 80% shrinkage around a complex shape, the ink used must be able to adhere to the substrate, resist cracking, and provide a high image quality, while the physical conditions of the underlying substrate change significantly," she says. "Heat resistance is the name of the game for retort packaging and boil in bag pouches. Both are examples of multilayer flexible packaging structures that are exposed to an intense heat and temperature either during package processing or by the end-user."

Tekni-Films' high-clarity PVdC coated PVC film is for blister packs.

Trends that dovetail

Environmentally responsible packaging is also top of mind in the industry today. Replacement as discussed by Derbyshire is one of the Rs of sustainable packaging. Think of the now familiar eight truckloads of cans to one of pouches.

The other Wal-Mart Rs—Remove, Reduce, Reuse, Recycle, Renew, Revenue, and Read—are important, agrees Sal Pellingra, innovation and marketing director at Ampac Flexibles. "For us," Pellingra says, "redesign encompasses all of these. Sustainability is what you can do in all areas. Can you reduce the package or use renewable materials or new structures to differentiate yourself from your competitors?

"For example, you can change out a foil for a metallized film. You can reduce three or four layers of lamination to two or three. The key is how do you do that and improve the existing shelf appeal?" Pellingra also stresses that the larger issue, though, is whether the new materials can run on the existing equipment in the field. If you're switching from a bottle to a pouch for water, for example, a commitment to new equipment would be required. "As for foil, the thicker structures are more forgiving than film but film is starting to make some inroads," Pellingra continues. "The length of time it takes to change is also an issue. We do accelerated shelf life testing but the companies also want a full year of testing."

Pellingra and Ampac also see ultra high barrier metallized film as a large trend from a material reduction and shelf life perspective for items like salty snacks. "I have seen a UHB film achieve shelf life of a year for a potato chip bag," he says. "That's huge from a waste standpoint. The remove date can be lengthened and a company can do longer runs."

Last summer, Ampac introduced Flexi-Free 6836, a solventless overwrap lamination for primary or secondary packaging applications. The company says it is ideally suited for applications that require excellent barrier properties but where the highest performance characteristics provided by more expensive foil-based structures are not needed. The clear top polyester layer can be flexographically printed on the reverse side for consumer applications, such as pre-moistened wipes, dietary supplements, nutrition bars, single-use coffee packs, etc. As an overwrap, it works for secondary applications such as medical devices, transdermal patches, vials, etc.

New interest in renewables

There is also an impetus among packagers to move to films made from renewable resources—principally wood pulp and vegetable starches. The rising cost of petroleum products, the country's dependence on foreign oil, and the current move to sustainable practices are all motivators.

"Sustainable packaging has moved from an interesting concept to a commercial reality," says Malcolm Cohn, Market Manager for the Americas, Innovia Films in Atlanta. "Bioplastics can't do everything, but they can do more and more each year and in certain applications can outperform conventional polymers. The difficulty is to get market retailers to pull them through the supply chain. They are generally more expensive."

Innovia's biodegradable and compostable film line, NatureFlex, is cellulose-based made from renewable wood pulp. The pulp is obtained from FSC-certified tree plantations. It offers high gloss and transparency, is easy to print and offers several choices for food as well as other products. Cohn notes that in Europe, fresh produce is often prepackaged. Prepackaging helps to define what's organic and what isn't. Now that trend is starting to catch on in the U.S. "Two years ago, Wal-Mart offered organic kiwis in a palm fiber tray over wrapped with NatureFlex," he says. "Since then Wild Oats (now Whole Foods), Safeway, and Thrifty have used NatureFlex, but there's still a long way to go."

On the other hand, Trader Joe's (the Monrovia, CA, boutique grocery chain now going nationwide) packages produce like its mini tomatoes in structured bio-based polylactic acid (PLA) packaging from Cargill-owned Nature Works. Considered a sustainable alternative to petrochemical-derived products, PLA is derived from renewable agricultural products, particularly corn. Ampac also offers Apex 3000 SF, which is made from a proprietary blend with a high percentage of PLA.

Last spring, DuPont Packaging expanded its Biomax Strong family of polymer additives to include an FDA compliant grade for food contact applications. These additives improve the performance of PLA packaging. Then, last September, DuPont and Plantic Technologies Limited, an Australian company specializing in high-amylose corn starch-based biopolymers, announced plans to collaborate in developing and selling renewably sourced polymers made from Plantic technology.

Shanna L. Moore, Dupont's global business director for sustainable packaging materials, says thermoform trays that are water degradable are important for the food industry but have a wide range of applications outside of food—including personal care products, electronics, and display trays.

Moore also says: "The big opportunity outside of food is replacing clamshells and blister packs. These are prime candidates for flexible film. They reduce a package's environmental footprint. Retailers want clamshells because they are theft resistant, but clamshells are not consumer friendly. Our challenge is to provide materials that are consumer and environmentally friendly and tough enough to deter theft."

The package designer's challenge, however, is to enhance shelf appeal in the face of change. Moore is upbeat. "Designers are going to have a lot of fun getting creative as brand owners reduce their products' footprints," she says.

Noel Jeffrey regularly covers print production, digital imaging, print-on-demand, and related subjects for graphics trade media. Contact her at noeljeff1@earthlink.net.