Multilayered polymer films and process for the preparation thereof

A process for preparing a multilayered polymer film, comprising the steps of:

• providing a first polymer consisting of a polyolefin;
• melt processing said first polymer to produce at least one first polymer layer;
• providing a polymer blend comprising about 1 to about 40 parts by volume of a polyolefin, about 99 to 60 parts by volume of an anisotropic liquid crystalline polymer, and 0.1 to 5 parts by volume of a compatibilizer;
• melt processing said polymer blend at a viscosity ratio between the anisotropic polymer and the polyolefin [λ=ηanisotropic polymer/ηisotropic polymer] in a range of about 0.5 to 5 to produce a polymer compound essentially consisting of a laminar layer composed of a continuous liquid crystalline polymer base;
• and
• processing said polymer compound into a second polymer layer, the second layer having an oxygen transmission rate of less than about 150 cm3/(m2·d·bar), determined according to ASTM D 3985-81, and the multilayered polymer film having a water vapor transmission rate of less than 10 g/(m2·d·bar) at RH 80% 23° C., determined according to ASTM F 1249-90.

A method for manufacturing a container for food stuff or chemicals, which comprises the step of forming a container from a laminate comprising:

• a substrate;
• and
• at least one polymer layer coated on a surface of said substrate to act as a barrier to transport of oxygen and water vapour through the laminate, the polymer layer consisting essentially of a multilayered polymer structure having at least one first layer consisting of a polyolefin, at least one second layer arranged adjacent to said first layer and containing a liquid crystalline polymer, and a tie layer that adheres the second layer to the first layer, the second layer consisting essentially of a compounded and compatibilized polymer blend formed by the liquid crystalline polymer, a polyolefin and a compatibilizer, the liquid crystalline polymer of the second layer forming a continuous phase, the second layer having an oxygen transmission rate of less than 150 cm3/(m2·d·bar), determined according to ASTM D 3985-81, and the laminate having a water vapor transmission rate of less than 10 g/(m2·24·h) at RH 80% 23° C., determined according to ASTM F 1249-90, the second layer containing 60 to 99% of the liquid crystalline polymer, 1 to 40% of the polyolefin, and 0.1 to 5% of the compatibilizer enhancing an interaction between the liquid crystalline polymer and the polyolefin, contents of the polymers and the compatibilizer being based upon total volume of the second layer.

A multilayered polymer film structure for use as a barrier layer in packages, consisting essentially of:

• at least one first layer containing a polyolefin;
• at least one second layer arranged adjacent to said first layer and containing a liquid crystalline polymer, the second layer consisting essentially of a compounded and compatibilized polymer blend formed by the liquid crystalline polymer, a polyolefin and a compatibilizer, the liquid crystalline polymer of the second layer forming a continuous phase, the second layer having an oxygen transmission rate of less than 150 cm3/(m2·d·bar), determined according to ASTM D 3985-81, and the integral film structure having a water vapour transmission rate of less than 10 g/(m2·24·h) at RH 80% 23° C., determined according to ASTM F 1249-90, the second layer containing 60 to 99 parts by volume of the liquid crystalline polymer, 1 to 40 parts by volume of the polyolefin, and up to 0.1 to 5 parts by volume of the compatibilizer enhancing an interaction between the liquid crystalline polymer and the polyolefin, contents of the polymers and the compatibilizer being based upon total volume of the second layer;
• and
• a tie layer that adheres the second layer to the first layer, the compatibilizer being a functionalized polyolefin comprising an oleofinic polymer functionalized with one of the group consisting of epoxy, carboxylic acid, anhydride, hydroxyl, amine, carbonyl and oxazoline groups and combinations of these groups.

A multilayered polymer film structure for use as a barrier layer in packages, consisting essentially of:

• at least one first layer containing a polyolefin;
• at least one second layer arranged adjacent to said first layer and containing a liquid crystalline polymer, the second layer consisting essentially of a compounded and compatibilized polymer blend formed by the liquid crystalline polymer, a polyolefin and a compatibilizer, the liquid crystalline polymer of the second layer forming a continuous phase, the second layer having an oxygen transmission rate of less than 150 cm3/(m2·d·bar), determined according to ASTM D 3985-81, and the integral film structure having a water vapour transmission rate of less than 10 g/(m2·24·h) at RH 80% 23° C., determined according to ASTM F 1249-90, the second layer containing 60 to 99 parts by volume of the liquid crystalline polymer, 1 to 40 parts by volume of the polyolefin, and 0.1 to 5 parts by volume of the compatibilizer enhancing an interaction between the liquid crystalline polymer and the polyolefin, contents of the polymers and the compatibilizer being based upon total volume of the second layer;
• and
• a tie layer that adheres the second layer to the first layer, at least two of the first layers being provided, one on each side of the second layer, the tie layer being of maleic anhydride grafted copolyethylene on each side of the second layer for adhering each of the first layers to a respective side of the second layer.