| 摘要 |
PURPOSE:To drastically enhance refractive index and surface roughness by introducing polycarbonate resin specified in mol.wt. between a pair of double belts and press- molding it at the specified temp. and pressure in the inlet roll part thereof and then leading the molded form to an outlet part to take it while slowly cooling it at the specified temp. conditions between the double belts. CONSTITUTION:Aromatic polycarbonate having 15,000 - 35,000 mol.wt. is melted in an extruder 1 and extruded into a sheet shape from a T-die 2 and led to the inlet part of a double belt pressing device. The sheet shape is pinched between the upper and lower specular steel belts 3, 3' and press-molded at 160 - 280 deg.C and 10 - 250kg/cm<2> by the rolls 4, 4' in the inlet part. The specular surfaces of the steel belts 3, 3' are transferred and the sheet shape is molded into prescribed thickness. Then it is passed through the guide rolls 6. 6' in a state wherein it is pinched between the specular steel belts 3, 3'. It is slowly cooled at 160 - 240 deg.C in 0.5 - 10 minutes in the slowly cooling zones 9, 9' to remove an optical strain. Then it is led to the cooling zones 10, 10' and slowly cooled at <= 150 deg.C. The upper and lower specular steel belts 3, 3' are peeled in the peeling roll 7, 7' parts and thereafter the molded article is taken out from the double belt pressing device. |
