| 摘要 |
PURPOSE:To obtain the film excellent in surface smoothness and useable for the base plate of a printed circuit board, etc. by a method in which after the aromatic polyether sulfon liquid with specified rotary viscosity has been cast on a supporting body by a coating tool of a scraper type, the solvent contained therein is removed. CONSTITUTION:Aromatic polyether sulfon is gradually added into the solvent such as N, N dimethyl formamide and dissolved, and then the insoluble part therein is separated by filtration, whereby the liquid with 10<2>-2X10<5> centipoise rotary viscosity at 25 deg.C is obtained. Next, after this liquid has been cast on a supporting body such as a glass plate by a coating tool of a scraper type, the contained solvent is removed and then it is dried and separated from the supporting body. The separated film is heated and dried at 170 deg.C and for 3hr, while fixing the ends of the film, thereby obtaining the objective film. |
