Extrusion Dies Industries LLC claims its new microlayer technology can reduce the oxygen transmission rate (OTR) in film and sheet for packaging by up to 80 percent.
By transforming a single layer of a resin such as [ethylene vinyl alcohol] into several microlayers, it is possible to reduce OTR by 60-80 percent, said Gary Oliver, vice president of technology. And while EVOH is a crystalline, relatively brittle material, replacing a single thick layer with multiple microlayers increases formability for thermoforming and flexi- bility for vacuum skin packaging.
To make the multilayered material, EDI uses a tool called a multiplier to create layers within a coextrusion sandwich. The structure is then fed into the manifold of an extrusion die to make film or sheet.
At the Chippewa Falls-based company's technology center, EDI used the system to multiply the EVOH core layer in sheet used for single-portion cups, such as those used to package fruit cocktails.
EDI manufactured cups made from sheet with one, four, eight and 16 EVOH layers. All sheet structures were 50 mils in thickness, with thick (41-43 percent) skin layers of polypropylene and tie layers between the skins and the EVOH core.
Thirty days later, cups with a single layer of the grade of EVOH had OTR rates three to six times higher than multiple layer cups, according to the firm.
Layer multiplication is especially promising for sheet and thick-film packaging such as rigid retort and hot-fill containers, stand-up retort pouches and vacuum skin packaging for meat, said Oliver. Thickness matters particularly in the case of barrier microlayers. The technology will be shown at K 2010.
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