EVOH Film

What EVOH Barrier Layer Does

EVOH is used as a barrier layer of composite film and is normally handled in the flexible packaging plant during production. Where oxygen ingress limits shelf life, the EVOH layer provides the gas barrier inside the structure instead of relying on foil or coating alone.

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Three Processing Methods on Conventional Equipment

EVOH can be co-extruded with polyolefin or polyamide, laminated as film to other substrates, or applied as EVOH resin coating on various substrates or a single container. With no special change it can be processed on conventional processing equipment, so no dedicated line is required.

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Biaxially Stretched EVOH Film Characteristics

Between EVOH resin molecules there is high cohesive energy inside, so the film is not easy to draw. Biaxial stretching therefore uses higher ethylene content grades such as EP-G115 with ethylene mole fraction of 48 percent. The stretched film gives high tensile strength, impact strength and puncture resistance comparable with nylon film.

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Why Coextruded EVOH Keeps Barrier After Folding

Co-extruded EVOH film has no organic solvent residue, which fits health requirements for food packaging. The layers combine from the co-extrusion die lip with good inter-layer integration, so the film keeps its original barrier properties after repeated twists and turns, while polyester aluminum foil composite is damaged at the bend and loses barrier.

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How to Select Three to Nine Layer Structures

Common EVOH co-extruded film structures have three, five, seven and nine layers and are formed in one continuous pass, which simplifies the process and reduces cost. The barrier layer can be made very thin as the intermediate layer against moisture, while the two outer layers use heat seal resin selected for bag sealing.

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