Barrier Coatings for Food Packaging

With the global customer base for retailed food increasing, food packaging must more and more conform to international food quality, and safety standards. This also can mean longer shelf life is a necessity.

Increased global consumer awareness, income, combined with busier lifestyles, is creating a growing demand for convenience foods. Consumers typically want the food they buy to be safe to eat, stay fresh longer, and meet their taste, and appearance preferences. Essential to this end is food packaging that can extend shelf life, and maintain food freshness.

Barrier CoatingsSimply stated, consumers want protective economic food packaging that offers easy open, and see through features, combined with barrier protection from degrading oxygen, water vapor, and aromas.


Barrier and other functional coatings encompass materials that are coated onto substrates to provide a barrier, and a package, to protect selected packaged goods. Barrier coatings, providing barriers for food packaging requirements, may include protection against oxygen and aromas, liquid water and water vapor, oils, and grease.

Barrier PerformanceAn effective barrier can prevent both losses from the packaged product, and penetration into the package, both of which can affect quality, and shorten product shelf life. Packaged food products are being maintained fresh longer as a result of new materials, and food processing developments.

For example, O² scavengers are now being used that work within a sealed package to limit O² reaction with a food product. Combined with effective O² barrier packaging, food packagers have the ability to improve shelf life, preserve product appearance, and flavor, while minimizing preservative use. Additionally, antimicrobials, while under siege, have been proven effective as additives to coatings, and packaging films, in combating food sourced illnesses. 


Barrier Coating NanotechnologyNanotechnology is being applied to improve the gas barrier properties of coatings. In doing so, nanoclay is dispersed in barrier coatings, resulting in a platelet orientation that creates a "torturous path" for gas molecules to traverse, yielding a very thin film, effective gas barrier.

Traditionally, tinplated steel, glass and aluminum have provided the ultimate in oxygen O² and moisture MVTR barrier materials for food packaging. These packaging materials offer zero gas, and vapor transmission rates. Glass, of course, has the added benefit of being transparent.

Recycling, environmental friendliness and sustainability have become issues for all packaging, providing the opportunity for new packaging materials development. As a result, continual improvements in polymer films, surface treatments, and coatings are yielding new packaging alternatives while respecting environmental impact.

Single or multilayer plastic films generally lack the ability to provide an optimum gas barrier. The addition of aluminum foil lamination is an industry standard offering an optimum gas and MVTR barrier; however these are expensive and not transparent.  

Water MoleculeMetallized aluminum and transparent oxide coated plastic films provide useable O² and MVTR performance. Inorganic AlOx and SiOx oxides deposited by electron sputtering are not cost effective. However, AlOx and SiOx metallized by vapor deposition to films is cost effective. SiOx and AlOx coatings are commonly used on PET and BON films.

Unfortunately, these coatings are not heat sealable so they are used in multilayer film constructions sandwiching the damage susceptible oxide film between plastic film layers. Oxide film depositions on films may also be protectively in-line coated using sol-gel materials.

The global growth of these inorganic transparent barrier films is forecast to grow at high rates even with their gas and MVTR limitations compared to aluminum foil. They are attractive for stand-up pouch applications, meat pack lidding, microwavable, retort and dry food packaging.

MVTR BarrierCommonly used plastic packaging films based on polyethylene terephthalate PET, biaxially oriented polypropylene BOPP, biaxially oriented nylon BON/OPA, polyactic acid PLA, and cellulose MXXT/W, MS lack in the gas barrier properties required for long shelf life food packaging.

Seeking to overcome these deficiencies a variety of coatings have been developed. These have, with a variation of results, improved gas barrier properties, as well as offered heat seal capabilities, product resistant properties, transparency, and gloss.

These coatings include both organic solvent and aqueous polyvinylidene chloride PVDC, aqueous polyvinyl alcohol PVOH, aqueous, and extrusion coated ethylene vinyl alcohol EVOH, and organic and inorganic sol-gels. Each of these exhibits desired performance limitations of one sort or another.


Currently, there is great interest and promising developments involving in-line applied barrier coating technology based on new organic polymer chemistry utilizing nano-particulate materials in aqueous or solvent systems. These new generation coatings are designed to be capable of being applied in-line by flexo, gravure and litho tower coating processes.

ln-line applied barrier coatings are demonstrating the ability to enhance the O² barrier performance of aluminum metalized, and oxide coated films while improving abrasion resistance, and flexibility. Furthermore, these coatings are showing potential to be used by film manufacturers or converters to produce significant high O² barrier packaging without the need for expensive metalizing or oxide coating.

The attainment of both oxygen O² and moisture vapor barrier MVTR in a single polymer-based coating has remained elusive.

Next up, expect to see the commercialization of single polymer-based systems, utilizing nano technology featuring both high O², and MVTR barrier properties along with desirable green properties. The evolution of new forms of high barrier, transparent plastic packaging should be the result.

Presumably UV curing single film system barrier coatings will also be on the horizon.

NOTE:

Cork Industries, as a leader in food contact coatings, does not use any fluorinated chemicals in the production of any of its products, especially in direct and indirect food contact coatings.  Cork Industries provides superior barrier coatings without the use of these potentially harmful chemicals.

PFOA FREE • PFOS FREE • PFAS FREE

Cork’s barrier coatings do not use fluorinated chemicals in any of its products; all are PFOA free, PFOS free, and PFOA free. We offer an entire line of robust, cost effective barrier coatings that DO NOT contain fluorinated chemicals.

Cork continues to advance its environmentally responsible GREEN technology utilizing sustainable renewable (bio) resource materials content. See more about Barrier Coatings Here