| abstract |
A retardation film is manufactured by stretching a thermoplastic resin film while adjusting stretching ratio α [%], temperature β [° C.], and stretching speed γ [%/min] so that the following formulas (1) and (2) are satisfied when the thermoplastic resin film is stretched at the stretching ratio α [%], the temperature β [° C.], and the stretching speed γ [%/min], therefore, stretching unevenness can be prevented:n nZ>X (1)n n( X×100/ k)×0.2<( Y−X )×100/ k (2)n nhere X represents yield stress [MPa] in a stress-strain curve, Y represents stress [MPa] in the stress-strain curve when the film is further stretched from the yield stress by k [%] which is the amount of strain until the yield stress, and Z represents stress [MPa] in the stress-strain curve when the film is stretched to α [%]. |