| 摘要 |
PURPOSE:To prevent the warp of a crystalline polypropylene resin sheet by cooling the sheet by a slow cooling rotary roll immediately after the sheet is extruded and before the sheet is passed between pressing rolls. CONSTITUTION:After extruded by a T-die 2 fitted on a uniaxial extruder 1, the sheet is slowly cooled by the contact with the surface of a slow cooling rotary roll 3. The sheet is then further cooled by the contact with a emboss finished pressing roll 4, a mirror finished pressing roll 5, and a cooling roll 6. The sheet is then cut up along the extrusion direction to form out-size sheets. In this method, the resin sheet has a temperature of 210 to 270 deg.C immediately on extrusion, is cooled down to a temperature of 150 to 180 deg.C at a cooling rate smaller than 10 deg.C/sec by the roll 3, and is cooled down to a temperature of 100 to 140 deg.C by the pressing rolls 4 and 5. |
