Encapsulated barrier for flexible films and a method of making the same

摘要

Disclosed is a film structure comprising: a thermally sensitive barrier layer made from a first polymeric material comprising ethylene vinyl alcohol copolymer, wherein the first polymer has a melt temperature range between about 400 °F and about 450 °F; first and second layers disposed on opposite surfaces of the barrier layer wherein the first and second layers are made from a second polymeric material having a melt temperature between about 400 °F and about 450 °F and wherein the first and second adhesive layers are formed by encapsulating the barrier layer with the second polymeric material; a third adhesive layer on an outside surface of the first adhesive layer having a melt temperature between about 550 °F and about 620 °F, wherein the barrier layer and first, second and third adhesive layers are coextruded together to form an extrudate; and at least one substrate layer formed separately from and adhered to the extrudate. Also disclosed is a method for manufacturing a film structure, the method comprising: providing a first extruder for extruding a thermally sensitive barrier material comprising ethylene vinyl alcohol copolymer; extruding said barrier material; providing a second extruder for extruding a first adhesive material; extruding the first adhesive material; encapsulating the barrier material by the first adhesive material in a first encapsulator to form a first extrudate at a first temperature; providing a second adhesive material; extruding the second adhesive material via a third extruder; adhering the first extrudate to the second adhesive at a second temperature to form a combined meltstream wherein the second temperature is higher than the first temperature; feeding the combined meltstream through a die to form a flat sheet wherein the flat sheet includes a barrier layer encapsulated by first adhesive layers on opposite sides of the barrier layer and further wherein at least one of the first adhesive layers are bonded to a second adhesive layer on an outside surface of the first adhesive layers; and laminating the sheet to at least one substrate formed separately from the sheet.