Polyimide-based film having excellent surface evenness and method for producing same

A polyimide-based film having a Kc value of 1.55 or less,

• wherein the polyimide-based film is produced by:
• preparing a liquid resin composition using monomer components including dianhydride and diamine,
• producing a gel-state film using the liquid resin composition,
• first drying the gel-state film at a temperature of 50 to 150° C. at a wind speed of 0 m/s or less for a drying period of 2 to 20 minutes, and
• second drying the gel-state film at a wind speed of 1.0 to 5.0 m/s at 70 to 140° C. after the first drying,
• wherein the Kc value is a curvature parameter measured for a waviness having a wavelength range of 1.0 to 3.0 mm by phase stepped deflectometry,
• wherein a polyimide-based film sample having a width of 15 cm×a length of 15 cm×thickness of 80 μm is used for measuring K, and
• a measuring device is in a curvature mode K with 1.0 to 3.0 mm wavelength range, and a sheet of black matte paper is placed on a surface plate in a dark room, the sample to be measured is placed thereon, the Kc value is measured 10 times, and the average value is used as the Kc value of the sample,
• wherein the polyimide-based film is produced from monomer components including dianhydride and diamine,
• the dianhydride comprises at least one selected from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, pyromellitic dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, 4,4′-(3,4-bisdicarboxyphenoxy-diphenyl sulfide dianhydride, 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 4,4′-(4,4′-Isopropylidenediphenoxy)bis(phthalic anhydride), cyclobutane-1,2,3,4-tetracarboxylic dianhydride, 1,2,3,4-cyclopentane-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and dicyclohexyl-3,4,3′,4′-tetracarboxylic dianhydride,
• the diamine comprises at least one selected from 3,4-oxydianiline, 4,4′-oxydianiline, p-phenylenediamine, m-phenylenediamine, 4,4-methylenedianiline, 3,3-methylenedianiline, 1,3-Bis(3-aminophenoxy)benzene, 1,3-Bis(4-aminophenoxy)benzene, 2,2′-bis[4-(4-aminophenoxy) phenyl] hexafluoropropane, 2,2′-bis(3-aminophenyl)hexafluoropropane, 2,2′-bis(4-aminophenyl) hexafluoropropane, bis(4-aminophenyl)sulfone, bis(3-aminophenyl)sulfone, 2,2′-bis(trifluoromethyl)benzidine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, bis[4-(4-aminophenoxy)phenyl] sulfone, bis[4-(3-aminophenoxy)phenyl] sulfone, 9,9-bis(4-aminophenyl)fluorene and 9,9-bis(4-amino-3-fluorophenyl)fluorene.