| 摘要 |
<p>1. An opaque, biaxially oriented polymeric film structure comprising: (a) a core layer, having a first surface and a second surface, comprising a thermoplastic polymeric matrix within which is located a stratum of voids; a substantial number of the voids containing at least one spherical, void-initiating particle which is phase distinct and incompatible with matrix material, the population of voids in the core being such as to cause a significant degree of opacity; and (b) at least one skin layer, adhering to at least the first surface of the core layer, comprising a thermoplastic polymeric matrix within which is located a stratum of voids, a substantial number of said voids containing at least one void-initiating solid particle which is phase distinct and incompatible with the matrix material. r</p> |
