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An apparatus for producing a thermoplastic film 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 in a c

An apparatus for producing a thermoplastic film 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 in a calendering roll stack wherein, at least one roll consists of an inner steel shell, a resilient covering over the inner steel roll and a multi-layer metal sleeve outer covering of at least two layers. The metal sleeve preferably consists of three layers. The inner layer of the multi-layer outer sleeve is preferably nickel, the intermediate layer is preferably copper and the outer layer 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.

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1. A continuous film extrusion process for producing a transparent or translucent thermoplastic film for optical media applications having a low birefringence, low stress and wherein at least one surface of the film has a roughness of less than about 4 microinches and a retardation value of less tha

1. A continuous film extrusion process for producing a transparent or translucent thermoplastic film for optical media applications having a low birefringence, low stress and wherein at least one surface of the film has a roughness of less than about 4 microinches and a retardation value of less than about 100 nanometers, which process comprises:extruding a molten thermoplastic film, andpassing the molten thermoplastic film through an opening between two opposing calendaring rolls wherein at least one calendaring roll is a finishing roll and subsequently cooling the hot thermoplastic film to a temperature below its solidification temperature of the thermoplastic film, said finishing roll is a multi component structure comprised of an inner steel shell, an intermediate resilient covering over the inner steel and a multi-layer metal sleeve outer covering comprised of at least two layers. 2. The process of claim 1, wherein the cooled thermoplastic film has a thickness of about 0.001 to about 0.060 inches. 3. The process of claim 1 wherein at least one surface of the thermoplastic film has a roughness of about 0.5 to about 2.0 microinches. 4. The process of claim 1 wherein the 2 opposing calendaring rolls are finishing rolls used to produce a thermoplastic film of low birefringence, low stress and wherein bath surfaces of the thermoplastic film have a roughness of less than about 4 microinches. 5. The process of claim 4 wherein both surfaces of the thermoplastic film have a roughness of about 0.5 to about 2.0 microinches. 6. The process of claim 1 wherein the multi-layer metal sleeve outer covering has a total thickness of about 0.005 inches to about 0.020 inches. 7. The process of claim 1 wherein the multi-layer metal sleeve outer covering further comprises three-layers with a chrome outer layer having a thickness of about 0.0002 inches to about 0.002 inches. 8. The process of claim 7 wherein the multi-layer metal sleeve outer covering further comprises an inner layer having a thickness of about 0.002 inches to about 0.010 inches and comprising a material selected from the group of nickel and a nickel based alloy. 9. The process or claim 8 wherein the multi-layer metal sleeve outer covering further comprises a middle layer disposed between the outer layer and the inner layer, and wherein the middle layer comprises copper and has a thickness of about 0.005 inches to about 0.020 inches. 10. A continuous film extrusion process for producing a thermoplastic film having low stress and wherein at least one surface or the film has a roughness of less than about 4 microinches and a retardation value of less than about 100 nanometers, which process comprises:extruding a molten thermoplastic him, and passing the molten thermoplastic film through an opening between two opposing calendaring rolls wherein at least one calendaring roll is a finishing roll and subsequently cooling the hot thermoplastic film to a temperature below its solidification temperature of the thermoplastic film, said finishing roll is a multi component structure comprised of an inner steel shall, arm intermediate resilient coveting over the inner steel and a multi-layer metal sleeve outer covering comprised of at least two layers. 11. The process of claim 10, wherein the cooled thermoplastic flint has a thickness of about 0.001 to about 0.060 inches. 12. The process of claim 10, wherein at least one surface of the thermoplastic film has a roughness of about 0.5 to about 2.0 microinches.