Optical film
An optical film having at least one layer formed of a polyolefin based resin composition containing 8 to 30 wt % of a component (A) defined below and 92 to 70 wt % of a component (B) defined below, with the proviso that the total of the component (A) and the component (B) is 100 wt %: component (A): an olefin based polymer with which neither a crystal fusion peak having a crystal fusion heat of 30 J/g or more nor a crystallization peak having a crystallization heat of 30 J/g or more to be observed in the range of −50 to 200° C. is observed in a differential scanning calorimetry measurement according to JIS K 7122; and component (B): a propylene based polymer with which a crystal fusion peak having a crystal fusion heat larger than 30 J/g or a crystallization peak having a crystallization heat larger than 30 J/g to be observed in the range of −50 to 200° C. is observed in a differential scanning calorimetry measurement according to JIS K 7122.
1. An optical film comprising at least one layer formed of a polyolefin based resin composition containing 8 to 30 wt % of a component (A) defined below and 92 to 70 wt % of a component (B) defined below, with the proviso that a total of the component (A) and the component (B) is 100 wt %:
component (A): an olefin based polymer with which neither a crystal fusion peak having a crystal fusion heat of 30 J/g or more nor a crystallization peak having a crystallization heat of 30 J/g or more to be observed in the range of −50 to 200° C. is observed in a differential scanning calorimetry measurement according to JIS K 7122; and
component (B): a propylene based polymer with which a crystal fusion peak having a crystal fusion heat larger than 30 J/g or a crystallization peak having a crystallization heat larger than 30 J/g to be observed in the range of −50 to 200° C. is observed in a differential scanning calorimetry measurement according to JIS K 7122.
2. The optical film according to claim 1 , wherein the component (A) is a polymer satisfying the following formula (1):
0 ≦[x /( x+y )]<0.6 (1)
(in the above formula (1), x represents a content (% by mole) of a monomer unit derived from ethylene in the component (A), and y represents a content (% by mole) of a monomer unit derived from an α-olefin having 4 to 20 carbon atoms in the component (A), with the proviso that a total amount of the component (A) is 100% by mole).
3. The optical film according to claim 1 , wherein the component (A) is an olefin based polymer with which neither a crystal fusion peak having a crystal fusion heat of 1 J/g or more nor a crystallization peak having a crystallization heat of 1 J/g or more to be observed in the range of −50 to 200° C. is observed in a differential scanning calorimetry measurement according to JIS K 7122.
4. The optical film according to claim 1 , wherein the component (B) is a propylene based polymer having a melting point of 145° C. or less.
5. The optical film according to claim 1 , which has been stretched at least uniaxially.
6. The optical film according to claim 1 which is a retardation film.
7. The optical film according to claim 1 which has a present ratio C of a crystal oriented in a film-width direction being 0.75 or more and 0.85 or less and a degree of orientation D of the crystal oriented in the film-width direction being 80% or more and 95% or less, which are determined from a diffraction peak observed in a region near 2θ=16 to 16.5° in a wide-angle X-ray diffraction image.
8. The optical film according to claim 1 which has a present ratio C of a crystal oriented in a film-width direction being 0.90 or more and 1.00 or less and a degree of orientation D of the crystal oriented in the film-width direction being 60% or more and 85% or less, which are determined from a diffraction peak observed in a region near 2θ=16 to 16.5° in a wide-angle X-ray diffraction image.