Preparation and properties of polyimide multilayer films via roll coating technique

The mechanical and corona resistance of polyimide/alumina multilayer composite films were prepared by roller coating process. The mechanical properties and corona resistance of the films were tested, and compared with the single layer of polyimide/alumina composite films. The results show that the multilayer composite film can maintain the mechanical properties of the film and improve the corona resistance of the film when the same mass fraction of alumina is introduced. The results show that the alumina in the single layer is spherical agglomerated, while that in the multilayer composite film is strip. The surface layer of strip dense alumina in multilayer composite films plays a role in preventing corona discharge from penetrating into the internal organism and the discharge is concentrated on alumina. The aluminum oxide with inner strip distribution continues to resist corona discharge, and changes the path of corona discharge, which prevents the corona breakdown from happening in advance, so the corona resistance of composite film has been improved.