| 摘要 |
PURPOSE:To manufacture a low temperature heat-sealing polyester film economically by feeding raw melting point polyester resin pellets in the uncrystalline and undried state into a biaxial extruder directly, carrying out melting and dehydrating simultaneously, and then laminating with a high melting polyester layer in a die and coextruding. CONSTITUTION:When a low temperature heat-sealing polyester film composed of a high melting point polyester layer having the melting point of 230 deg.C or over and a low melting point polyester layer having the melting point of 150 deg.C or under formed at least on one surface of said high melting polyester layer, first, low melting polyester resin pellets in the uncrystalline and undried state are fed directly into a biaxial extruder provided with a vacuum vent device and melting and dehydrating simultaneously. Also, dried pellets of the high melting polyester resin are fed into a conventional high speed discharge extruder and melt extruded. High melting polyester resin and low melting point polyester resin in the molten state are guided to a multimanifold type or feed-block type multi-layer die and laminated therein. A film extruded out of the multi-layer die is solidified on a cooling roll, and then stretched in the vertical and horizontal directions simultaneously by a tenter type simultaneous biaxial stretching machine. |
