| 摘要 |
PURPOSE: To suppress cap stripes while reducing thickness irregularity by dividing the flow of a thermoplastic resin into a plurality of passages and cooling at least one passage to temp. lower than extrusion temp. but equal to or higher than temp. falling crystallization start temp. and laminating the thermoplastic resins from both passages to extrude them from a cap. CONSTITUTION: The flow of the thermoplastic resin melted in an extruder is divided into a plurality of passages and at least one passage is cooled to temp. lower than the extrusion temp. of the thermoplastic resin from the extruder but equal to or higher than the temp. falling crystallization start temp. of the thermoplastic resin. Next, the thermoplastic resins sent from the respective passages are laminated to be extruded from a cap and the extrudate is molded on a cooling roll. As the thermoplastic resin, a polyolefin resin, a polyamide resin or a polyester resin is used. A melt extrusion method is performed using the extruder and the flow of the molten resin is divided into a plurality of passages to increase a cooling specific area and the surface of the thermoplastic resin is held to non-solidifying temp. without extending passage length. |
