▎ 摘　　要

NOVELTY - Preparing polyimide film comprises adding nano powder and dispersant in aprotic polar solvent under nitrogen atmosphere, ultrasonically dispersing for 30-60 minutes, stirring for 6-12 hours, allowing to stand and curing for 24-48 hours and filtering to obtain nano powder curing agent dispersion A, blowing nitrogen into aprotic solution for 30 minutes, adding diamine monomer, stirring to completely dissolve, adding dianhydride monomer, stirring at 25-60 degrees C for 4-48 hours to obtain polyamide solution B with viscosity of 5000-200,000 mPax second, adding nano powder curing agent dispersion A into polyamide solution B, uniformly stirring, vacuuming degassing for 0.5-12 hours, coating on glass plate through slit to obtain uniformly distributed glue film, introducing glue film in drying box, drying at 60-160 degrees C for 5-30 minutes, taking out, peeling off glass plate to get glue film, introducing film in high-temperature oven for carrying out high-temperature heat treatment, and cooling. USE - The method is useful for preparing polyimide film. ADVANTAGE - The film: has high strength, high modulus, glass transition temperature exceeds 430 degrees C, and the coefficient of thermal expansion is less than 7 ppm/ degrees C. DETAILED DESCRIPTION - Preparing polyimide film comprises adding nano powder and dispersant in aprotic polar solvent under nitrogen atmosphere, ultrasonically dispersing for 30-60 minutes, stirring for 6-12 hours, allowing to stand and curing for 24-48 hours and filtering to obtain nano powder curing agent dispersion A, blowing nitrogen into aprotic solution for 30 minutes, adding diamine monomer, stirring to completely dissolve, adding dianhydride monomer, stirring at 25-60 degrees C for 4-48 hours to obtain polyamide solution B with viscosity of 5000-200,000 mPax second, adding nano powder curing agent dispersion A into polyamide solution B, uniformly stirring, vacuuming degassing for 0.5-12 hours, coating on glass plate through slit to obtain uniformly distributed glue film, introducing glue film in drying box, drying at 60-160 degrees C for 5-30 minutes, taking out, peeling off glass plate to get glue film, introducing film in high-temperature oven for carrying out high-temperature heat treatment, and cooling, where the polyimide film containing 0.1-10 wt.% nano-particle curing agent.