Paper360 - March/April 2016 - (Page 40)

techlink | BARRIER PACKAGING Barrier Technologies: The Next Revolution in Food Packaging PABLO GARCIA When it comes to food, most people no longer live in a fresh-to-table environment. A 2010-2011 study commissioned by the Food and Agriculture Organization of the United Nations entitled "Global Food Losses and Food Waste" found that approximately "one-third of food produced for human consumption is lost or wasted globally, which amounts to about 1.3 billion tons per year." Current methods used for food storage and distribution contribute to increased pollution and greenhouse gas emissions. As a result, there is a growing demand for food barrier-packaging solutions that not only shield and protect the quality of extended shelf-life foods, but that are also bio-based, recyclable and biodegradable. To many people's surprise, paper is fast emerging as the potential answer. The technical advancements of ethylene vinyl alcohol (EVOH) and polyvinyl alcohol (PVOH) technologies now allow the paper industry to address consumer demands for sustainable packaging that safeguards food quality while minimizing spoilage and waste. These materials offer an opportunity to move paper food packaging from its traditional role of portion containment packaging to protecting and preserving the quality of our nutrition. EVOH EVOH is a high gas barrier thermoplastic that is melted, extruded and converted into plastic bags, cups, trays, bottles and jars. It has traditionally been used in household food packaging for products like baby foods and shredded cheese. This technology is Figure 1: Formula for EVAL resin. 40 Paper360º MARCH/APRIL 2016 Figure 2: The EVOH chemical chain. also applied every day in automotive plastic fuel tanks, pipes for floor heating systems and agricultural fumigation films. With a semi-polar, semi-crystalline molecular structure, EVOH provides an excellent barrier against the permeation of hydrocarbon compounds, as well as gases such as oxygen, carbon dioxide and nitrogen. In fact, it offers gas barrier protection between 10,000 and 25,000 times more than typical low-density polyethylenes commonly found in conventional plastic bags. Kuraray is a leading producer of EVOH, and first commercialized it in 1972 under the name EVAL. The EVAL resin is represented by the formula in Fig. 1. Because it shuts out oxygen, EVAL can limit chemical deterioration as well as slow microbial degradation of the food from the ingress of oxygen over time. It also locks in aromas, ensures flavor is maintained and protects sensitive vitamin content. It is suitable as a plastic packaging material for mayonnaise, ketchup and a broad range of perishable and other extended shelf-life foods. EVOH products like EVAL can be the perfect complement to hybrid structures that combine separate paper and plastic structures, such as bag-in-box packaging (common to boxed wines), as well as barrier-coated paperboard packaging for juices, soups, dairy products and sachets for soup powder, spices and tea. PVOH PVOH is a synthetic resin that has been used for years to coat paper for sizing, strengthening and as a carrier for pigments and optical brightening agents used to increase the paper's opacity and whiteness. The resin's emulsification, adhesion to minerals and hydrocarbon impermeability also make it a key component of specialty inkjet, carbonless, thermal and silicone release liner papers. PVOH's vinylalcohol based chemistry and similarity to EVOH's barrier properties also suit it for applications in food barrier packaging. A semi-polar, semi-crystalline, linear polymer, PVOH's functional barrier characteristics work the same as EVOH in terms of a low permeability to oils, greases, oxygen, carbon dioxide and nitrogen. But under dry conditions, its higher polarity and crystallinity leads it to surpass EVOH's barrier performance. In addition, it has good film-forming capability over paper substrates, with excellent adhesion to the wood fiber. A soluble polymer powder, it is dissolved into water to create a viscous transparent solution that is then coated onto paper using a size press or a blade, rod or air knife coater. PVOH is typically characterized by its degree of polymerization (or DP, which indicates the length of the molecule) and Figure 3: Molecular structure of PVOH.

Table of Contents for the Digital Edition of Paper360 - March/April 2016

Over the Wire
Engineering: A Continuing Evolution
RISI’s European CEO of the Year
Sappi Europe: Serious About the Future of Paper
Reliability and Maintenance Beliefs – Part IV
Discovering Hidden Causes of Converting Problems
Barrier Technologies: The New Revolution in Food Packaging
Standard Bleaching Sequences Including an Ozone Stage – Part I
TAPPI Journal Summaries
Consolidation Watch
SWM Gets Faster ERP Financial Data
Battling Rejection Burnout
Association News
Index of Advertisers

Paper360 - March/April 2016