Polyimide film and process for producing the same
View Patent ↗The polyimide film of the present invention is produced in the following manner: polyamic acid made of a combination of a specific acid anhydride constituent and a specific diamine constituent are heated under a low-pressure circumstance for heat imidation, and the obtained imide is dissolved again in a solvent to be polyimide solution, then the polyimide solution is formed to be a film. In this manner, it is possible to provide a polyimide film essentially transparent and colorless, and has sufficient toughness to prevent occurrences of a crack or a break when the film is folded and creased by hand.
1. A polyimide film, which uses a soluble polyimide resin obtained by diamine constituent and acid dianhydride constituent, wherein the diamine constituent is a compound denoted by a following chemical formula (1), wherein the acid dianhydride constituent is denoted by a following chemical formula (2),
H 2 N—A—R—B—R—A—NH 2 (1)
A. A SINGLE BOND OR A BIVALENT HYDROCARBON GROUP HAVING 1 TO 3 CARBON ATOMS
OR A SINGLE BOND
A SINGLE BOND OR A BIVALENT HYDROCARBON GROUP HAVING 1 TO 10 CARBON ATOMS
THE Zs ARE INDEPENDENT IN THE FORMULA.
OR DENOTES A SINGLE BOND,
Y DENOTES,
OR DENOTES A SINGLE BOND (n IS IN A RANGE FROM 1 TO 10)
wherein the polyimide film has a transparency of not less than 70% with respect to light with a wavelength of 440 nm and has a tearing strength of not less than 2N/mm when it is 75 μm thick.
2. The polyimide film of claim 1 , manufactured by a method comprising the steps of:
1) mixing and polymerizing the diamine constituent and the acid dianhydride constituent in a solvent so as to obtain a polyamic acid solution,
2) heating the polyamic acid solution under a low-pressure circumstance of not more than 0.9×10 5 Pa for imidation so as to obtain a polyimide resin;
3) dissolving the polyimide resin thus obtained in a solvent;
4) casting and applying a polyimide solution obtained through the step 3) to a supporting body so as to coat the supporting body with the polyimide solution; and
5) drying and solidifying the polyimide solution.