| 摘要 |
PROBLEM TO BE SOLVED: To enable a foreign matter to be completely removed when a plastic insulator is extruded by an extruder by allowing a composition to pass through a metal fiber filter before the extruder extrudes a plastic composition in a specified form following its kneading process. SOLUTION: Before a plastic composition is kneaded and extruded as a plastic mixture of a specified form by an extruder, the plastic mixture is allowed to pass through a metal fiber filter. This metal fiber filter is of the thick filtration type obtained by laminating pieces of unwoven cloth of metal fine fibers with different fiber diameters and sandwiching the unwoven cloth between a protecting layer and a support layer and further, processing these materials completely in one piece. In addition, this filter has a high filtration efficiency, low filtration resistance and superior foreign matter capturing capacity. Thus it is possible to form a plastic insulating layer which is completely free from foreign matter. |
