Optically absorptive anisotropic film, three-dimensional optically absorptive anisotropic film and method for producing the same
An optically absorptive anisotropic film includes a dichroic dye. The light absorbances of the film satisfy the formulas (1), (2) and (3): Az >( Ax+Ay )/2 (1) Ax ( z =60)/ Ax >5 (2) Ay ( z =60)/ Ay >5 (3) wherein Ax, Ay, Az, Ax (z=60) and Ay (z=60) are absorbances at a local maximum absorption wavelength of the dichroic dye; Ax, Ay and Az represent an absorbance of linearly polarized light vibrating in the direction of the x-axis, y-axis and z-axis, respectively; Ax (z=60) represents an absorbance of the linearly polarized light vibrating in the direction of the x-axis in the state of the film rotated by 60° around the y-axis; and Ay (z=60) represents an absorbance of the linearly polarized light vibrating in the direction of the y-axis in the state the film rotated by 60° around the x-axis.
1. An optically absorptive anisotropic film comprising a dichroic dye and a liquid crystalline compound, wherein,
when an arbitrary direction in the film plane is defined as an x-axis, the axis orthogonal to the x-axis in the film plane is defined as a y-axis and the axis orthogonal to the x-axis and the y-axis is defined as a z-axis, the light absorbances of the film satisfy the formulas (1), (2) and (3):
Az >( Ax+Ay )/2 (1)
Ax ( z= 60)/ Ax >5 (2)
Ay ( z= 60)/ Ay >5 (3)
wherein Ax, Ay, Az, Ax (z=60) and Ay (z=60) are absorbances at a local maximum absorption wavelength of the dichroic dye contained in the film;
Ax represents an absorbance of linearly polarized light vibrating in the direction of the x-axis;
Ay represents an absorbance of linearly polarized light vibrating in the direction of the y-axis;
Az represents an absorbance of linearly polarized light vibrating in the direction of the z-axis;
Ax (z=60) represents an absorbance of the linearly polarized light vibrating in the direction of the x-axis in the state of the film rotated by 60° around the y-axis;
Ay (z=60) represents an absorbance of the linearly polarized light vibrating in the direction of the y-axis in the state the film rotated by 600 around the x-axis.
2. The optically absorptive anisotropic film according to claim 1 , wherein the liquid crystalline compound forms a smetic liquid crystal phase.
3. The optically absorptive anisotropic film according to claim 1 , wherein the liquid crystalline compound forms a high order smectic liquid crystal phase.
4. The optically absorptive anisotropic film according to claim 1 , wherein the optically absorptive anisotropic film exhibits a Bragg peak in x-ray diffraction measurement.
5. The optically absorptive anisotropic film according to claim 1 , wherein the local maximum absorption wavelength of the dichroic dye contained in the optily absorptive anisotropic film is in a wavelength range of 500 to 600 nm.
6. The optically absorptive anisotropic film according to claim 1 , wherein the optically absorptive anisotropic film satisfies the formulas (4) and (5),
Ax ( z 60)/ Ax> 10 (4)
Ay 1 z− 60)/ Ay> 10 (5).
7. The optically absorptive anisotropic film according to claim 1 , wherein the optically absorptive anisotropic film comprising at least three dichroic dyes differing in a local maximum absorption wavelength.
8. The optically absorptive anisotropic film according to claim 1 , wherein the optically absorptive anisotropic film has a thickness of 5 μm or less.
9. An optical film comprising the optically absorptive anisotropic film according to claim 1 and a substrate.
10. The optical film according to claim 9 , wherein the optical film has no orientation film between the optically absorptive anisotropic film and the substrate.
11. A method for producing the optical film according to claim 9 , the method comprising the following steps of (1), (2), (3) and (4) to be performed in this order:
(1) a step of forming a coating layer by coating a substrate with a composition comprising the liquid crystalline compound, the dichroic dye and a solvent;
(2) a step of forming a dried layer by removing the sol vent from the coating layer;
(3) a step of developing a liquid crystal phase by cooling the dried layer; and
(4) a step of curing the liquid crystalline compound by applying active energy rays.
12. The method according to claim 11 , wherein an elongated film is used as the substrate and the optical film is produced continuously.
13. A three-dimensional optically absorptive anisotropic film in which the optically absorptive anisotropic film according to claim 1 is laminated together with a horizontal polarizing film, wherein,
when an absorption axis of the horizontal polarizing film is defined as an x′-axis, a transmission axis of the horizontal polarizing film is defined as a y′-axis and the axis orthogonal to the x′-axis and the y′-axis is defined as a z′-axis, the three-dimensional optically absorptive anisotropic film satisfies the formula (6):
Ax′>Az′>Ay′ (6)
wherein Ax′, Ay′ and Az′ are an absorbances at a local maximum absorption wavelength of the dichroic dye contained in the optically absorptive anisotropic film;
Ax′ represents an absorbance of linearly polarized light vibrating in the direction of the x′-axis;
Ay′ represents an absorbance of linearly polarized light vibrating in the direction of the y′-axis; and
Az′ represents an absorbance of linearly polarized light vibrating in the direction of the z′-axis.
14. The three-dimensional optically absorptive anisotropic film according to claim 13 , wherein the horizontal polarizing film comprises a polyvinyl alcohol and a dichroic dye.
15. The three-dimensional optically absorptive anisotropic film according to claim 13 , wherein the horizontal polarizing film comprises a dichroic dye and a liquid crystalline compound, or comprises a dichroic dye having liquid crystalline properties.
16. The three-dimensional optically absorptive anisotropic film according to claim 13 , wherein the optically absorptive anisotropic film is laminated on the horizontal polarizing film via a pressure-sensitive adhesive or an adhesive.