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US 2006/0038314 A1Published application
Method for producing low birefringence plastic film
OwnerKevin Capaldo, Dennis Coyle +2inventors
InventorsKevin Capaldo, Dennis Coyle, Safwat Tadros, Kang Xi
Life of this patent
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Abstract
In one embodiment, the extrusion process can comprise: feeding a thermoplastic polycarbonate resin to an extruder; heating the resin to a temperature sufficient to attain a melt viscosity of less than or equal to about 300 Pa.s; extruding the heated resin; and passing the extruded resin through a gap between two solid metal calendering rolls to produce a film. The film has a birefringence of less than or equal to about 50 nm.
Claims11
An extrusion process, comprising:
- feeding a thermoplastic polycarbonate resin to an extruder;
- heating the resin in the extruder to a melt temperature that is above a glass transition temperature of the resin, thereby producing a melt of the thermoplastic polycarbonate resin;
- extruding the melted resin downwardly through an extrusion nozzle orifice having a slot configuration;
- passing the melted resin downwardly into a gap between two calendering rolls at least one of which has a highly polished surface, and wherein the calendering rolls are maintained at a roll temperature of less than the glass transition temperature;
- and
- cooling the thermoplastic polycarbonate resin film to below its glass transition temperature as the thermoplastic polycarbonate resin film advances through the gap.
3 more elements
An extrusion process, comprising:
- extruding melted thermoplastic polycarbonate resin downwardly through an extrusion nozzle orifice, wherein the melted thermoplastic polycarbonate resin has a viscosity of less than or equal to 600 Pa.s;
- passing the melted thermoplastic polycarbonate resin through a gap between two calendering rolls, wherein at least one of the calendering rolls has a polished surface, wherein the calendering rolls have a roll temperature of less than or equal to about 140° C.;
- and
- cooling the melted thermoplastic polycarbonate resin to below its glass transition temperature to form a polycarbonate film;
- wherein the polycarbonate film has a retardation of less than or equal to about 35 nm.
2 more elements
An extrusion process, comprising:
- feeding a thermoplastic polycarbonate resin to an extruder;
- heating the resin to a temperature sufficient to attain a melt viscosity of less than or equal to about 300 Pa.s;
- extruding the heated resin;
- and
- passing the extruded resin through a gap between two solid metal calendering rolls to produce a film;
- wherein the film has a birefringence of less than or equal to about 50 nm.
3 more elements
Dependencies are inferred from the claim text.