| 摘要 |
PURPOSE:To improve the impact strength of sheet by a method wherein fiber base material, which consists of only aramid fiber mixed paper having the specified mixing ratio of aramid fiber to cellulose fiber or of the aramid fiber mixed paper and cellulose fiber paper in combination, is impregnated with thermosetting resin and, after that, formed under heat and pressure. CONSTITUTION:The ratio of aramid fiber to cellulose fiber by weight percentage is set to be 50:50 to 5:95. The fiber base material is used in the form of only aramid fiber mixed paper or of aramid fiber mixed paper and cellulose fiber paper in combination. The cellulose fiber paper is the paper used for ordinary laminated sheet such as kraft paper, linter paper or the like. By drying the fiber base material impregnated with thermosetting resin varnish, prepreg is obtained. The ratio of resin in the prepreg lies normally in the range of about 40 - 60%. Under the condition that the predetermined number of said prepregs are piled up and, when necessary, copper foil is put on the surface of the piled-up prepregs, forming under heat and pressure is performed normally at 150 - 170 deg.C and 100 - 120kg/cm<2> for 90 - 120min. |
