Novel h‐ BN ‐Modified Polyesterimine Resin Mica Tape Composites With High Thermal Conductivity and H‐Class Thermal Stability

ABSTRACT Lower thermal stability class and thermal conductivity ( λ ) of mica tape limit the service life of stator winding insulation in large generators. A novel mica tape composite was prepared by replacing epoxy resin with heat‐resistant polyesterimine and incorporating hexagonal boron nitride (h‐BN) filler, mica paper, and glass fiber cloth, which can overcome the thermal stability and λ of epoxy tapes, with a multiscale model established for performance prediction. The experimental results demonstrate that the h‐BN‐modified polyesterimine resin mica tape exhibits a heat‐resistant class of H. At an h‐BN loading of 25 wt%, the λ of the h‐BN‐modified polyesterimine resin mica tape attains 0.497 W/(m K), representing a 116.09% enhancement compared to the polyesterimine resin mica tape (0.23 W/(m K)). Through integration of the Y. Agari and Series model, a second‐order thermal conductivity model (Y–S) was developed for h‐BN‐modified polyesterimine resin mica tape composites, demonstrating enhanced accuracy in predicting λ . Furthermore, the h‐BN‐modified polyesterimine resin mica tape composites prepared in this paper exhibit excellent dielectric properties, with a material insulation strength of > 30 kV/mm. This provides a new approach for the preparation of mica tape composites with high heat‐resistance class and high thermal conductivity.