Paper or Plastic?

Evolution and Revolution in Packaging Material
at Interpack and Pack Expo

By Terry Bedell

Would you like plastic or paper? That standard question from your supermarket cashier is getting to be more complex than it used to be, but that may not be all bad. At Interpack 2005 and Pack Expo Las Vegas, it was clear that identifying the specific material to meet the needs of barrier protection, physical properties, aesthetics, and environmental impacts is both more challenging and more rewarding than it once was.

At Interpack, the newest class of options, biopolymers, were highlighted in a large special pavilion set up in the center of the exhibition complex. The steady flow of visitors through that structure attests to the high level of interest in this area, as well as to the fact that biodegradable products are being made and sold in major markets around the world.

There has been much press over the past couple of years about PLA (polylactide) which is made and sold by NatureWorks, a Dow Cargill subsidiary. PLA is derived from plant sugars and is completely biodegradable. The films and containers made from PLA have excellent clarity and generally good physical properties although the material can be brittle and have minimal barrier properties.

The number of converters and their customers is growing rapidly in Europe, the U.S., and Asia. There is considerable work in progress to improve the physical properties of films and containers made from PLA to make it more competitive with PET. The most recent applications for PLA are for bottled water and milk bottles in regional markets in the U.S., as cost reductions make PLA more competitive.

Another very important development in biopolymers is a new material from Procter & Gamble Chemicals called Nodax (www.nodax.com). Nodax is made from polyhydroxybutyric and polyhydroxy alkanoic acids (PHA) that are biologically synthesized copolymers produced by microorganisms. Properties can be analogous to polypropylene or to other polymers depending on the specific molecule and additives used. This material will also be completely biodegradable. NODAX resins are still in the early stages of pilot production and the earliest expectation for commercial quantities is later this year.

The fact that a major consumer goods manufacturer is investing in this technology is strong validation that these materials will become realistic alternatives to other plastics in the foreseeable future. There were other biodegradable materials exhibited in the biopolymer pavilion including some starch-based materials (www.plantic.com and www.novamont.com) and some derived from cellulose (www.innoviafilms.com). Both of these materials are being used for specific applications but are unlikely to have the widespread market impact that is expected from PLA and the PHA options.

Advanced barrier films

Do you need a high barrier film to protect your product, a film that also offers excellent clarity and gloss? XPET 700, a 14-micron film from ExxonMobil Chemical, is coated on one side with high-barrier polyvinylidene chloride (PVdC). This provides an oxygen barrier of less than 8cc/m2/day and water vapor barrier of less than 0.8g/m2/day. When laminated to a hermetic sealant film, it offers a solution for MAP packaging to extend the shelf life of fresh foods such as meat, cheese, and baked goods.

Another version of the film, the 13-micron XPET 800 film is coated on one side with polyvinyl alcohol (PVOH), a non-halogenated polymer. This results in an oxygen barrier of below 1cc/m2/day in dry conditions. The film provides a packaging solution for dry meats and spices, for some refrigerated applications where gas or chemical protection is required, and where aroma preservation is essential.

Or perhaps you have a product that is very heat sensitive and needs a film that can be sealed at very low temperatures. The ExxonMobil very low temperature sealing and coating (VLTSC) technology enables the sealing range of its coated films to be expanded up to approximately 80º C (175º F), while meeting the demand for higher speeds from HFFS machines and providing more operational flexibility. Designed for optimum packaging machine performance and high speeds, this new coating technology allows packaging on horizontal form-fill-seal (HFFS) equipment at improved speeds and reduced costs.

The expanded seal range allows these films to tolerate speed and temperature fluctuations for a wider operational window. The addition of a barrier coating to the film enables excellent printing and stiffness for horizontal packaging formats, and this film has an excellent barrier for aroma and water vapor transmission.

More technology advances

Ciba Specialty Chemicals has developed Ciba Prime IT, a patented technology to improve adhesion of UV-curable or water-based inks, coatings, and adhesives on plastics. UV printing technologies allow high printing qualities to be achieved without the use of solvents and with very low energy consumption. However, adhesion of UV inks on plastics is sometimes poor, making it necessary to use physical or chemical treatments as primers. Compared to Prime IT, according to Ciba, other chemical treatments require higher quantities and additional procedures, involving, for example, the use of solvents or less environmentally compatible chemicals (www.cibasc.com/packagin).

Converters are offering new, high barrier transparent laminations that will tolerate heat processing of the pouch contents including microwave and retort conditions. Flexible pouches are becoming a viable alternative to metal cans or glass containers for virtually any product.

Graphic Packaging International, Inc. has developed a laminated film called Quilt Wave™ with a metallized layer that serves as a microwave susceptor (www.graphicpkg.co). The layers of the laminate are combined in a "quilt" pattern. When a pouch made with this material is heated in the microwave, the quilt panels bubble out and touch the product at the top of the bubbles. Since the metallized material rapidly transfers heat from the microwaves, this produces a grilled pattern on the product and drive away moisture, creating crisp, baked surface. The other benefit of this lamination is that it allows heat to dissipate rapidly so the package is not hot to the touch after cooking.

For packagers looking for a lower cost alternative to sparkling clear PET bottles, Milliken Chemical is offering a new clarifying agent for polypropylene that allows that lower cost material to be used on the same high output injection stretch blow-molding machinery. This is of particular interest for hot-filled or heat processed products (www.pp-isbm.com or www.millikenchemical.com).

Finally, the Global Speciality Papers Group of Stora Enso (www.storaenso.com/specialitypaper), the world's largest paper and board manufacturer, introduced MultiFlex™, a patented paper-based barrier packaging material. MultiFlex is a U.S. FDA approved, aluminum-free packaging solution for lidding, pouch, and OGR (oil and grease resistant) applications.

MultiFlex is a fluorochemical-free, sustainable paper-based barrier package could be marketed worldwide as a viable alternative to film and foil packaging materials. It was designed to effectively preserve food product freshness by building a strong barrier to moisture and oxygen, while sealing in natural aromas and flavors. As an aluminum-free packaging paper solution, MultiFlex allows for improved post-fill inspection and RFID compatibility.

Terry Bedell is president of TAB Packaging Technology Inc. with 40 years of experience in consumer products packaging R&D mostly with the Clorox Company. He can be reached at 925-200-6132 or e-mail at tbedell@comcast.net Terry helped PakIntell, LLC prepare a study of leading packaging innovations from Interpack 2005 entitled Package & Technology Integrated Solutions (www.pakintell.com).