Importance

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Abstract

A controlled permeability film composition including a film forming polymer; an inert porous filler in an effective amount to reduce the ratio of carbon dioxide permeability to the oxygen permeability of the film; and wherein the filler has a particle size greater than the intrinsic film thickness of the composite film; and a non-porous filler having a particle size larger than that of the inert pour filler and being present in an amount in an effective amount to control excessive variablility of oxygen transmission rate through film upon activation of the film by compression, for example, by roll crushing. Preferably the porous filler is present in an amount sufficient to reduce the ratio of carbon dioxide to oxygen permeability of the controlled permeability film. The addition of the non porous filler provides improved properties, for example, better permeability/temperature behavior, more consistent film properties and better CO.sub.2 /O.sub.2 permeability ratio. The larger non porous particles help control the variability of the OTR of the film by serving as a buffer to reduce the sensitivity to the pressure activation.

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First Claim