| 摘要 |
PURPOSE:To obtain film, which has high surface accuracy and Young's modulus and is excellent in heat resistance by a method wherein the means shearing speed of solution at its passing through a slit is specified and the mixture of two or more para-aramids is used. CONSTITUTION:The film concerned is produced on wet method or dry method by extruding para-aramid solution through a slit die on a supporting surface. At that time, the solution is extruded at the means shearing speed of 50/sec at its passing through a slit. In addition, the mixture of two or more para- aramids, the logarithmic viscosity numbers of which are different from each other by 0.2 or more and the major para-aramid of which does not exceed 90% of the total weight is used. As the above-mentioned para-aramids, the polymers represented by formulae I and II or their copolymer is used. The obtained film has favorable slipperiness between films, between film and metal and between film and ceramics in addition to its good surface accuracy and consequently is useful as base film for magnetic tape, electrical insulating material, dielectric for capacitor, base film for printed wiring board and self-adhering tape printed with bar code. |
