| 摘要 |
PURPOSE:To provide a method for manufacturing a polycarbonate(PC) sheet wherein thermal contraction is little even by reheating in postforming, and dimensional precision of a molded product has been improved. CONSTITUTION:While PC resin is extruded in a molten sheet state from a die 16 of an extruder and received with pitch rolls 17, the extruded PC sheet 14 is introduced between the first polishing roll 11 and the second polishing roll 12, and advanced on a peripheral surface of the second polishing roll 12. In a method for manufacturing the PC sheet wherein it is successively introduced between the second polishing roll 12 and the third polishing roll 13 to carry out sheeting, temperature of the first polishing roll is set at 130 to 140 deg.C, and temperature of the second and third polishing rolls is set at 180 to 190 deg.C. Besides, the PC sheet 14 is extruded at 260 to 280 deg.C. Further, the PC sheet 14 is heated before being introduced so that surface temperature of the PC sheet 14 in the introduction onto the third polishing roll can reach 190 to 200 deg.C. |
