Patent ID: 8906463

Claim:
A method for producing a polyimide film comprising: heating a coating film formed on a base material, the coating film formed from a solution composition comprising a polyamic acid having a repeating unit represented by chemical formula (1), the coating film remaining coated on the base material during the heating and a maximum heating temperature being in a range of 380° C.-450° C.; and obtaining a polyimide film without foaming, the film having a thickness of 40 to 120 μm and having an elastic modulus of 1,000 MPa or more at a temperature of 400° C., wherein, in the polyamic acid having the repeating unit represented by the chemical formula (1), 85 mol % or more in 100 mol % of A is chemical formula (2) and/or chemical formula (3); 85 mol % or more in 100 mol % of B is chemical formula (4); 175 mol % or more in 200 mol % of A plus B is any of chemical formulas (2) to (4); and 6 to 25 mol % in 200 mol % of A plus B is any of chemical formulas (5) to (7); and, in the chemical formula (7), X is direct bonding or a divalent group; R1 to R4 each independently are a substituent selected from hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, hydroxyl group, carboxyl group, an alkoxy group having 1 to 6 carbon atoms, and a carboalkoxy group; at least one of R1 and R2 is not hydrogen atom; and at least one of R3 and R4 is not hydrogen atom.