| 摘要 |
PROBLEM TO BE SOLVED: To obtain optical homogeneity, reduce the irregularity of double refraction phase difference and increase the thickness accuracy by holding an extruded film like thermoplastic resin in a circular arc state between a cooling roll made of metal regulated to specific temp. and an endless metal belt tensioned by a plurality of rolls controlled in pressure so as not to be slackened under pressure. SOLUTION: The thermoplastic resin 2 extruded from a T-die 1 in a molten state in a film form is guided on a cooling roll 3 to be cooled. An endless belt 9 is supported by two rolls 4, 6 and a belt press roll 7 is positioned at the almost intermediate point between a cooling drive roll 4 and a belt pulling roll 6 to be prevented from the contact with the endless belt 9. At that time, the cooling drive roll 4 is allowed to approach the cooling roll 3 from above to hold the resin 2 under pressure. The molding temp. of the cooling roll 3 and the endless belt 9 must be set to Tg+20 deg.C-Tg-30 deg.C. The endless metal belt 9 is pref. rotated so that the linear velocity of the outermost periphery thereof does not become slower than that of the outermost periphery of the cooling roll 3 made of metal. |
