| 摘要 |
Exemplary methods include includes providing a film comprising at least one polymeric material; widening the film under a first set of processing conditions in a first draw step along the crossweb direction such that in-plane birefringence, if any, created in the film is low; and drawing the film in a second draw step along a downweb direction, while allowing the film to relax along the crossweb direction, under a second set of processing conditions, wherein the second set of processing conditions creates in-plane birefringence in at least one polymeric material.
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