BIORIENTED POLYETHYLENE FILM WITH A HIGH WATER VAPOR TRANSMISSION RATE

摘要

Methods of producing polyethylene films having a desired water vapor transmission rate (WVTR) are provided. The methods include casting a polyethylene sheet which has a base layer of a polyethylene and a cavitating agent, and at least one layer of a WVTR-controlling material, and subsequent ly biaxially orienting the sheet to yield a film having the desired WVTR. The base layer has a porous microstructure and a WVTR substantially higher than the desired WVTR.