| abstract |
An oriented polyimide film which has a high Young's modulus, satisfactory resistance to moist heat, and low hygroscopicity. The polyimide film consists mainly of pyromellitic acid units and of 30 to 99 mol% p-phenylenediamine units and 1 to 70 mol% diamine units which are structural units represented by the following formula (II): (II) (wherein ArIIa and ArIIb each independently is a C6-20 aromatic group optionally having an unreactive substituent; and X consists of at least one member selected among -O-, -O-ArIIc-O-, -SO2-, and -O-ArIId-O-ArIIe-O-). It is characterized by having an in-plane Young's modulus of 3 GPa or higher in two perpendicular directions and having a moisture absorption as measured at 72% RH and 25°C of 3.3 wt.% or lower. |