| 摘要 |
PURPOSE: To manufacture a thermoplastic resin film having small surface roughness by a method wherein a thermoplastic resin is melted with heat and sent to a flat die, expanded in the cross direction, cooled to a specified temperature, and an extruded melting sheet is stuck to a cooling drum having water liquid film so as to cool and solidify. CONSTITUTION: A thermoplastic resin such as a polyolefin resin and a polyamide resin is melted by heating to a melting completion temperature or higher and sent to a flat die. The resin is expanded in the cross direction at a manifold in the die. Thereafter, the thermoplastic resin is cooled to the melting completion temperature or lower and a down temperature crystallization start temperature or higher at a land of the die and extruded so as to form a melting sheet. The melting sheet is stuck to a cooling drum having water liquid film, cooled, and solidified so as to obtain a desired film. At this time, electrostatic charge is preferably applied to the melting sheet, and the thickness of the water liquid film is set to 0.01-1μm. A surface roughness Ra of a thermoplastic resin film obtained in this way is made to be 1μm or below. |
