| 摘要 |
PROBLEM TO BE SOLVED: To provide a drawn film obtained by drawing a film formed by solution casting, making Rth value after drawing lower than the initial Rth value and having a low weight reduction percentage. SOLUTION: This drawn film is formed by drawing a film formed by solution casting and with retardation in the thickness direction having an initial value of 30 nm or larger, at temperature T to satisfy the following formula (I), and of which the weight reduction percentage, as measured by TG-DTA, after 60 min, at the temperature T is 5% or less. In the formula (I) 0.2≤(Rth(T)/Rth(I))≤0.9, Rth(T) is the retardation value in the thickness direction of the film measured at λ=590 nm after 3 min at temperature T when at least two sides of the film are held, and the Rth(I) is the initial value of the retardation in the thickness direction of the film measured at λ=590 nm. Also the weight reduction percentage is found with weight reduction percentage (%)=[ä(initial film weight)-(film weight after being kept at temperature T for 60 min)}/(initial film weight)]×100. COPYRIGHT: (C)2010,JPO&INPIT
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