Impact Plastics Blog

What is EVOH and How is it Used in Food Packaging?

Posted by Blake Kingeter on September 7, 2018

EVOH extends food shelf lifeIn the food packaging industry, using a material composition that extends shelf life is a key component to ensuring the safety of the product and preserving the taste of the food. In addition, using packaging material that prolongs a products shelf life can drastically cut down on waste of perishable products, and creates a longer window for grocery stores to stock product before it reaches the hands of the consumer. A great way to achieve this is by using a packaging material that reduces the amount of oxygen that permeates the plastic, such as EVOH. Continue reading to learn more about this barrier material.

While traditional thermoplastic resin materials, such as polypropylene, polyethylene and HIPS, all have a certain degree of inherent barrier properties, they are not typically seen as “barrier” materials. Polypropylene, for example, is naturally an excellent moisture barrier but does not perform as well when it comes to oxygen permeability. In order to protect the contents of the packaging from both oxygen and moisture, a barrier material must be incorporated into the composition of the sheet – and this is where materials such as EVOH come in.

So what is EVOH film and how does it contribute to increasing the shelf life of packaged food products?

Yogurt ContainersEVOH stands for Ethylene-vinyl alcohol copolymer and is a flexible, crystal clear, glossy thermoplastic copolymer. This material has excellent flex-crack resistance, and exhibits a high resistance to hydrocarbons, oils and organic solvents. EVOH is known for having some of the best barrier resistance to gases such as oxygen, nitrogen, and carbon dioxide which makes it particularly suited for packaging food, drugs, cosmetics, and other perishable products. When compared to other common films, EVOH is considered to have superior barrier properties. However, when exposed to moisture, EVOH loses its good gas barrier properties. For this reason, EVOH is often used in a multilayer co-extruded film structure with materials such as HDPE, PP and PET, all of which have superior moisture barrier properties.

Current EVOH Capabilities at Impact Plastics

Currently Impact Plastics’ EVOH capabilities are limited to the process of extrusion lamination. Through the process of extrusion lamination, a premade EVOH film is wound around a heated chrome roll, fed through the nip of the chrome rolls where the die lip meets, and laminated and bonded to the material being extruded from the die lip. Using this process, the EVOH film is laminated to the outer surface of the extruded sheet whether it is PP, PE, HIPS, etc. The configuration of EVOH on the surface of a monolayer sheet provides sufficient barrier properties, however barrier properties can be dramatically improved by the number of layers the sheet consists of.  


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Topics: Food Packaging, EVOH

Written by Blake Kingeter

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