| 摘要 |
PURPOSE:To obtain the subject film uniformly having many protruding inorg. particles and a high heat resistance by casting an arom. polyamic acid on a support, drying the resulting thin film, peeling the film off the support, coating the surface of the film with a liquid dispersion of inorg. particles and heat- treating the coated film. CONSTITUTION:A soln. of an arom. polyamic acid is cast on a support to form a thin film of the soln., which is then dried to form a self-supporting film constituted of the arom. polyamic acid and a polar org. solvent. The film is then peeled off the support and coated with a liquid dispersion of inorg. particles of 0.01 to 100mum in average size homogeneously dispersed in a low-boiling org. solvent to form a coating layer, which is then dried and heat-treated at a high rate while retaining the fine inorg. particles in the surface layer of the film. The inorg. particles of the above-mentioned size are respectively retained while partially being embedded. The resulting film has 1X10 to 5X10<8> particles/mm<2> uniformly all over the surface layer thereof. |
