| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical film which has reduced optical irregularities and achieves both a high Re and film uniformity in spite of a high in-plane retardation value, and a manufacturing method thereof.SOLUTION: The optical film has a film thickness of 20 to 60 μm and an Re(550) of more than 80 nm and 350 nm or less and satisfies Em/Es=(1.5 to 2.5) where Em is an elastic modulus value in a direction which is parallel to or vertical to an arbitrary side of the film and in which an elastic modulus of the film is maximum and Es is an elastic modulus value in a direction orthogonal to that direction. When a storage elastic modulus obtained by dynamic viscoelasticity measurement is denoted as E' and a storage elastic modulus at a room temperature is denoted as E'RT, the optical film satisfies following formula (in the formula, Trepresents a temperature at which E'RT is 1/10, Trepresents a temperature at which E'RT is 1/100, logE'represents a value of logE' at the temperature at which E'RT is 1/10, and logE'represents a value of logE' at the temperature at which E'RT is 1/100). |
