High-Barrier Packaging: Yesterday, Today, and Tomorrow

Food retailers bank on the fact that consumers notice the "image" of a product-basically, its packaging. But what about the product's overall performance: Is it fresh? How does it taste? How does it smell? Does it do what it's supposed to do? The image presented by the package may help sell the product, but product performance keeps customers coming back. And performance is exactly what today's high-barrier plastic films deliver.

High-barrier packaging can comprise several different layers and various types of resins, which provide advanced properties for such things as extended shelf life and the ability to let in certain gases to change product coloring.

The average consumer probably has no idea that the packaging of a typical product he or she might pick up weekly may have as many as six layers of plastic (even more are quite possible) and can sit on the shelf and remain fresh for several months, possibly up to a year.

For a number of years many companies -- both plastics suppliers and converters -- have been involved in the development of high-barrier packaging with various substrates, including plastic film, paper, and foil. Obviously, in one short article we cannot cover this subject in full and do justice to its history and current applications. Neither can we include all of the companies and organizations that have been involved in developing high-barrier packaging. But we can present the opinions of some industry professionals on basic trends: where it started, where it stands now, and where it is going in the future.

A Little History Please
The high-barrier industry has been around at least 20 years; that's how long consulting firm Kline & Co. Inc., Little Falls, NJ, has been tracking it, reports Kline senior consultant Jay Dwivedi.

Venki Chandrashkdar, director, polymer commercial development at Equistar Chemicals LP, Houston, TX, says his company has been involved in the market since the mid-70s. "In barrier packaging, we use tie-layer adhesives [polyolefins that bond dissimilar polymers together in a multilayer structure], and I believe those started with Chemplex [a preceding company of Equistar] in 1976."

Mark Foote, VP for Packaging Partners Ltd., Franklin, WI, says high barrier really had its beginnings in foil substrates, and it was much earlier than 20 years ago. "You can go back to the 50s, and companies such as Mill Print and Standard Packaging were starting to extrude polyethylene and then laminate to foils. Whenever the first thin-gauge foil was utilized, that would have been about the time that your really high-barrier product was available."

Dwivedi says that companies such as American National Can, Cryovac, and Printpack also took on early leadership rolls in the barrier film industry.

Today, according to a recently published study by Kline & Co., converting companies such as Huntsman, Bemis, and Reynolds share the top spots with those companies, in terms of market share, in the high-performance barrier film market.

Dwivedi's colleague at Kline & Co., Garrett Gee, business manager, packaging, says customer demand initially is what brought barrier films to the forefront in the packaging market, but he adds that cost was also a driver in the development of high-barrier films.

"Getting foods to the consumer in the freshest possible state is probably the number one driver. The number two driver, I think, is getting the optimum-performing, lowest-cost film substrate. In other words, getting the right value in use for the product. You don't want to have an overengineered film for a bag of potato chips."

Dan Ward, research specialist, Equistar, agrees that economics is behind the development and innovations in the high-barrier market. "The cost of production was a real driving force. The lightweight packaging itself was also a factor. With polymeric packaging replacing metal cans, glass, or rigid-type structures, you needed barrier materials and coex structures."

According to Dwivedi, meat packaging is where a lot of the early "action" took place. "Once the technology was developed and perfected in that area, other market segments-snacks, cheese, and confectionery items-began to feature some of the same technologies, especially in the new area of diet-conscious snack food. As the amount of fat in food is reduced, the flavor-retention capabilities go down; lower-fat and fat-free foods made it necessary for film suppliers to come up with barrier packaging that would retain the flavor for a longer period of time."

Gee believes the two greatest exponential shifts in technology were from 1992 to 1996, and then again from 1996 until today. "In the early 90s, primarily you had four basic coating barrier materials: nylon, PVDC [polyvinylidene chloride], EVOH [ethylene vinyl alcohol], and metallized films. But the consumer demand to have fresher, more flavorful, higher quality foods has driven the demand for more sophisticated packaging solutions. Today you have multilayer film constructions that can get to 15 layers."

High Barrier Defined
Dean Zimmerman, research specialist for Equistar, defines high barrier as "any material that is capable of preventing the ingress of another material, whether it is gases or flavors or aromas. Typically, [high-barrier materials used today] are going to be oxygen barrier materials, of which the most common are EVOH and nylon resins. Those are used in conjunction with polyethylene, which is usually there to prevent moisture from entering."

In addition, Gee says polypropylene and polyester commonly are utilized for the base substrate in high-barrier packaging films. "Those three film bases are used to build multilayer structures, and then there are various processes and techniques to producing the film. The art is in balancing the overall ratio of cost to performance. Many companies will coextrude, some will laminate, others will coat. A lot of it is dependent on end-use applications. For instance, if a converter needs only a barrier film that performs moderately, they might coat a polyethylene substrate with PVDC or EVOH. That's a very cost-effective method."

Gee continues: "Another way a converter might achieve that same type of barrier is by taking a thinner film section of polyethylene and laminating it with a barrier layer with EVOH and then adding another layer of polyethylene onto it. But the composition of the packaging structure depends on many things: how many runs the company is going to make; the length of a single run; what physical properties must be achieved; will the end packages be vertical form-filled, or cold-sealed, or is the converter going to put a zipper onto it?"

Machine Considerations
The machines that produce these high-tech films have been modified and updated over the years. Dan Ward from Equistar notes that converters have been integral in machine advances. "A real driving force in the advent of coextruded film products was a converter by the name of Crown Zellerbach. From my perspective, from what I've seen and heard over the years, companies such as Crown Zellerbach designed their own equipment in order to make coextruded blown film and coextruded cast film. Many companies today make equipment modifications to produce their films, including food companies. Oscar Mayer did a lot of its own in-house machinery, as did any number of other major food companies, to accommodate the influx of flexible barrier packaging."

Where It's at Today
Today, high-performance barrier films, or high-barrier packaging, are utilized predominantly in the retail food market. Garrett Gee reports that "high-barrier packaging applications are accepted more readily in Europe and in Japan than in the US. The driver in Western Europe and in Japan is, really, that consumers have a much greater affinity and appreciation for food quality, and consuming food is more of a social event, whereas in North America it's more on a 'I want it quick, I want it hot, and I want it fresh' basis."

Dan Ward, though, says North America is "far ahead of the rest of the world in coextrusion technology. Some very good inventions have come from the [eastern part of the world], but I think that, primarily, the pioneering developments in coextrusion technology have come from American companies."

Other areas in which high-barrier packaging is utilized commonly, according to Gee, include medical devices, pharmaceuticals, and, to a lesser degree, tobacco, though he notes that the use of this type of packaging in the North American tobacco market has been declining significantly.

He adds that the packaging for pet food is an area in which there has been significant growth. "A big reason why flexible systems with barrier properties are emerging here is that barrier packaging helps prevent infestation. Many of these new flexible systems have some sort of foil and/or metallized or high-barrier packaging properties, and they now come with resealable zippers and other features like that."

Rich Knor, senior research specialist for Equistar, agrees that pet food packaging is utilizing high-barrier films more and more: "Now you can go into a supermarket or pet store, and there are these snack foods for cats and dogs. They are what I call a 'pegboard item'; they're hanging somewhere near the register as you check out."

The experts interviewed for this article seem to agree the industrial market sector is also an area in which applications and developments in high-barrier packaging are expanding. According to Gee, this area has seen "a tremendous amount of activity. Now we're seeing flexible packaging, high-barrier systems in lawn-and-garden products, in dry mixes, in salt containers like the kind used for melting ice."

Ward adds that another product utilizing these types of films is refrigerator liners; they are used, he says, to keep in the Freon-type products.

Activity in Variable Packaging
"Active packaging" is also a trend in plastic-film packaging, though Mark Foote says that this "variable" packaging isn't technically a high-barrier application.

Dan Zimmerman defines this "active" or "variable" packaging: "This is where you're no longer trying to keep gases out, but actually you can modify the gas that's inside the package. This type of packaging has what is referred to as 'oxygen scavengers.' The oxygen that is in the 'headspace,' or the gap in the package, is being absorbed and eliminated by putting various materials into the packaging structure. This is really popular in Japan, and I think it's going to be the next evolution in packaging: not just keeping gas out, but actually modifying the atmosphere inside."

Foote agrees that the variable packaging area is up and coming: "Especially for fresh-cut produce, this is one of the fastest growing areas in the flexible packaging business right now."

Well, there is the tip of the iceberg. For a more in-depth study on high-barrier packaging, contact Kline & Co. Provided below is contact information for Kline as well as for the other companies interviewed for this article.

For more information
Kline & Co. Inc., Little Falls, NJ; ph: 973/435-3445; fax: 973/435-6291.

Equistar Chemicals LP, Houston, TX; ph: 800/615-8999; fax: 713/309-4945.

Packaging Partners Ltd., Franklin, WI; ph: 414/427-4510; fax: 414/427-4520.

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