High orientation degree polyimide film, its preparation method and application

Abstract

This application relates to a highly oriented polyimide film, its preparation method, and its applications, belonging to the field of polymer materials technology. The film is made from a specific ratio of aprotic polar solvent, 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and optional functional fillers. The preparation method involves stepwise addition of pyromellitic dianhydride, followed by polymerization under high-speed shear stirring to obtain a highly uniform polyamic acid solution. Subsequently, the solution is cast, pre-cured by gradient heating to form a gel film, and then simultaneously biaxially stretched under heating conditions to induce molecular chain orientation. Finally, thermal imidization is completed through programmed temperature rise. The film obtained by this invention has advantages such as uniform thickness, high mechanical strength, excellent dimensional stability, and good electromagnetic shielding performance. It can be widely used in fields such as 5G flexible copper-clad laminates, flexible display packaging, and electromagnetic shielding films, improving the reliability of devices.