Permeable polypropylene film

摘要

A permeable, propylene-containing film structure including a core layer containing a propylene polymer matrix that has been cavitated by a two-component cavitation system, wherein the first component of the two-component cavitation system is a beta-nucleating agent to produce the beta-crystalline form of polypropylene and the second component is a filler. The film structure also includes first and second thermoplastic skin layers on either side of the core layer, respectively. A method of manufacturing a permeable propylene-containing film structure, including: forming a melt containing a propylene polymer, a beta-nucleating agent and a filler; cooling the melt to form a film layer; and stretching the film layer. The film structure has a water vapor transmission rate greater than 300 g/m²/day and a Gurley air permeability less than 3,000 s/10 cc.