Breathable film formed from a renewable polyester

摘要

A breathable film formed from a thermoplastic composition that contains a rigid renewable polyester and has a voided structure is provided. To achieve such a structure, a thermoplastic composition that contains a renewable polyester and polymeric toughening additive is extruded onto a surface to form a precursor film in which the toughening additive can be dispersed as discrete physical domains within a continuous matrix of the renewable polyester. The precursor film is thereafter stretched or drawn at a temperature below the glass transition temperature of the polyester (i.e., "cold drawn"). Without intending to be limited by theory, the present inventors believe that the deformation force and elongational strain of the drawing process causes debonding to occur in the renewable polyester matrix at those areas located adjacent to the discrete domains. This creates a network of voids located adjacent to the discrete domains.