| 摘要 |
<p>An apparatus for producing a thermoplastic film (21) having low-birefringent, low stress and at least one polished surface for optical media applications as well as low stress film for non-optical applications using a continuous extrusion process. The apparatus consists of a novel calendering roll (14) in a calendering roll stack (14, 16) wherein, at least one roll (14) consists of an inner steel shell (30), a resilient covering (28) over the inner steel roll (30) and a multi-layer metal sleeve outer covering (26) of at least two layers (36, 34, 32). The metal sleeve preferably consists of three layers (36, 34, 42). The inner layer (36) of the multi-layer outer sleeve (26) is preferably nickel, the intermediate layer (34) is preferably copper and the outer layer (32) is preferably chrome with a highly polished surface. The film produced by the process has a retardation value (birefringence times thickness) of less than about 100 nanometers and a surface roughness of less than about 4 microinches. The process is a continuous extrusion process for producing such film or sheet and does not require any further finishing operations.</p> |
