Polycarbonate resin film and manufacturing process thereof

A polycarbonate resin film,

• wherein:
• the polycarbonate resin film is a homopolymer of bisphenol A and has an average thickness of 10 to 150 a thickness nonuniformity of 2% or less, a retardation R(589) in the plane of the film measured at a wavelength of 589 nm of 12 nm or less, a retardation Rth(589) in the thickness direction of the film measured at a wavelength of 589 nm of 35 nm or less and is used for optical purposes;
• and
• the polycarbonate resin film is produced by a melt extrusion method in which a molten polycarbonate resin extruded into a film form from a die is circumscribed around a first chill roll, a second chill roll and a third chill roll sequentially to be cooled and then taken off,
• wherein:
• an air gap between the die and the first chill roll is 5 to 70 mm,
• a circumferential velocity R1 of the first chill roll, a circumferential velocity R2 of the second chill roll and a circumferential velocity R3 of the third chill roll satisfy R2/R1=1.002 to 1.050 and R3/R2=1.000 to 1.010,
• the temperatures of the three chill rolls are Tg to (Tg−15° C.), where Tg is the glass transition temperature of the polycarbonate resin,
• the film is taken off with a tension corresponding to a load applied to the film of 0.5 to 3.0 N/mm2 after it is separated from the chill roll, and
• the space between the first chill roll and the second chill roll and the space between the second chill roll and the third chill roll are 5 t to 100 t, where t is the thickness of the film to be produced.