The application discloses a preparation method of a five-element
copolymer high-Tg
polyimide film, which comprises the following steps: first, raw materials PDA, PMDA, M-TOLIDINE, ODA and S-
BPDA are weighed according to proportions; PMDA is divided into three parts of dianhydride
monomer A, dianhydride
monomer B and dianhydride
monomer C; PDA is dissolved in an
organic solvent to obtain a
diamine monomer solution; the dianhydride monomer A is added into the
diamine monomer solution to obtain a
mixed solution through stirring and mixing reaction; then, the M-TOLIDINE is added into the
mixed solution to perform stirring and mixing reaction, and then the dianhydride monomer C is added into the
mixed solution to perform stirring and mixing reaction; then, the ODA is added into the mixed solution to perform stirring and mixing reaction, and then the dianhydride monomer B is added into the mixed solution to perform stirring and mixing reaction; finally, the S-
BPDA is added into the mixed solution to adjust the
viscosity, and then the PAA is obtained through stirring and mixing reaction under a cold water bath condition; the PAA is coated on a glass plate, and then high-Tg
polyimide film is obtained through thermal imidization under temperature rising. The high-Tg
polyimide film produced by the application has good
heat resistance and
high heat dimensional stability, and promotes the application of the polyimide film product in the field of
flexible display substrates.