Optical film, elliptically polarizing plate, circularly polarizing plate, liquid crystal display element, and method of producing optical film
An optical film 10 of the present invention includes a plurality of optically anisotropic layers 13 which are laminated, wherein the optically anisotropic layer including: a photoalignment layer (A) 11 , in which a liquid crystal aligning capability has been generated by means of photoirradiation; and a polymer layer (B) 12 , which contains a liquid crystal compound that has a polymerizable group, and which is obtained by polymerization in a state where it has been aligned by the photoalignment layer (A) 11 , wherein the photoalignment layer (A) 11 and the polymer layer (B) 12 are bonded by covalent bonding. The plurality of optically anisotropic layers 13 may be an optically anisotropic layer 13 having a function of a one-half wavelength plate, and an optically anisotropic layer 13 having a function of a one-quarter wavelength plate.
1. An optical film comprising a plurality of optically anisotropic layers which are laminated, wherein the optically anisotropic layer comprises:
a photoalignment layer (A) in which a liquid crystal aligning capability has been generated by means of photoirradiation; and
a polymer layer (B), which contains a liquid crystal compound that has a polymerizable group, and which is obtained by polymerization in a state where it has been aligned by the photoalignment layer (A), wherein
the photoalignment layer (A) and the polymer layer (B) are bonded by covalent bonding, and
said photoalignment layer (A) contains a dichromatic dye that has a polymerizable group, whose mass average molecular weight is 1×10 2 to 5×10 3 ; or a dichromatic dye, whose mass average molecular weight is 1×10 2 to 5×10 3 , and a polymerizable compound whose mass average molecular weight is 50 to 1000.
2. An optical film according to claim 1 , further comprising an optically isotropic resin layer between two adjacent optically anisotropic layers.
3. An optical film according to claim 1 , wherein
at least one of said plurality of optically anisotropic layers is a first optically anisotropic layer in which the phase difference measured at a wavelength of 540 nm is 240 to 300 nm, and
at least one of said plurality of optically anisotropic layers is a second optically anisotropic layer in which the phase difference measured at a wavelength of 540 nm is 120 to 150 nm.
4. An optical film according to claim 1 , wherein said optically anisotropic layers are an optically anisotropic layer having a function of a one-half wavelength plate and an optically anisotropic layer having a function of a one-quarter wavelength plate.
5. An optical film according to claim 1 , wherein a laminated angle error of said plurality of optically anisotropic layers is within ±0.1°.
6. An optical film according to claim 1 , wherein said liquid crystal compound that has a polymerizable group is a rod-shaped liquid crystal compound.
7. An elliptically polarizing plate comprising an optical film according to any one of claim 1 through claim 5 or claim 6 , and a polarizing plate.
8. A circularly polarizing plate comprising an optical film according to any one of claim 1 through claim 5 or claim 6 , and a polarizing plate.
9. A liquid crystal display element that uses an optical film according to any one of claim 1 through claim 5 or claim 6 .
10. An optical film according to claim 1 , wherein a laminated angle error of the optically anisotropic layers produced by covalently bonding the photoaligning polymerizable composition layer and the polymerizable liquid crystal composition layer is within ±0.1°.