PRODUCTION OF LOW DIELECTRIC PRESSBOARD FOR OIL IMPREGNATION INSULATING

摘要

PURPOSE: To obtain the subject press board having a low dielectric constant, no fluff on the surface and low surface roughness by treating a press board having a low dielectric constant by a hot roll specified by temperature, pressure and speed. CONSTITUTION: The surface of a press board having a low dielectric constant composed of (A) kraft pulp and (B) a poly-4-methylpentene-1 fiber is treated by a hot roll at 210-300 deg.C at 80-250 kg/cm linear load at 4-200 m/minute treating speed to give the objective press board. Preferably, for example, an aqueous slurry obtained by mixing 70-90 wt.% of the component A having 200-400 ml freeness with 10-30 wt.% of the component B is subjected to wet paper making, a plurality of obtained papers are piled, integrated by pressurizing and heating and used.