Polyimide-based polymer film, substrate for display device, and optical device using the same

A polyimide-based resin film comprising a polyimide-based resin containing a polyimide repeating unit represented by the following Chemical Formula 1, wherein Bow is 40 μm or less:

• in the Chemical Formula 1,
• X1 is a tetravalent functional group represented by the following Chemical Formula 2,
• Y1 is an aromatic divalent functional group having at least 15 carbon atoms in which at least one electron-withdrawing group is substituted,
• in the Chemical Formula 2,
• Ar is a polycyclic aromatic divalent functional group,
• wherein the tetravalent functional group represented by Chemical Formula 2 includes a functional group represented by the following Chemical Formula 2-1:
• wherein the polyimide-based resin does not contain a repeating unit formed from pyromellitic dianhydride (PMDA),
• wherein the aromatic divalent functional group having at least 15 carbon atoms in which at least one electron-withdrawing functional group is substituted includes a functional group represented by the following Chemical Formula 3:
• in the Chemical Formula 3,
• T1 to T3 are the same as or different from each other, and each independently, an electron-withdrawing group,
• m1 to m3 are the same as or different from each other, at least one of m1 to m3 is an integer of 1 to 4, the rest are an integer of 0 to 4, and
• n is an integer of 1 to 10, and
• wherein the polyimide-based resin is formed from a repeating unit consisting of a combination of a tetracarboxylic dianhydrides and an aromatic diamine which is a compound in which an amino group is bonded to both terminals of the functional group represented by the Chemical Formula 3.