Optical layered body and display device
The present invention provides: an optical laminate comprising at least two films, the optical laminate comprising at least a film A satisfying a given condition (1) and a film C satisfying a given condition (2), wherein a retardation value Re(0) observed in a direction of an axis perpendicular to a plane of the optical laminate is 4,000 to 30,000 nm, and a retardation value Re(40) observed in a direction of an axis tilted from the axis perpendicular to the plane of the optical laminate toward a slow axis by 40 degrees in a plane lying perpendicular to the plane of the optical laminate and extending along the slow axis is 4,000 to 25,000 nm, the slow axis being an axis along which refractive index is highest in a plane of the film A; and a display device comprising the optical laminate.
1. An optical laminate consisting of:
at least one film A, each film A having an in-plane retardation of 4,000 nm or more and 20,000 nm or less, film A satisfying the following condition (1) wherein film A is an oriented film selected from the group consisting of a polyester film, a polycarbonate film, a cycloolefin polymer film, and an acrylic film;
at least one film C, each film C having an in-plane retardation of 200 nm or less, and a retardation in the thickness direction of 1,000 nm or more and 10,000 nm or less, film C satisfying the following condition (2) wherein film C is selected from the group consisting of a polyimide film, a polyaramid film, a polyamide-imide film, and a polyether ether ketone film; and
at least one layer selected from the group consisting of an adhesive layer, a hard coat layer, an anti-fouling layer, a conductive layer, an anti-reflection layer, an anti-glare layer, an ultraviolet absorption layer, and an anti-static layer,
wherein a retardation value Re(0) observed in a direction of an axis perpendicular to a plane of the optical laminate is 4,000 to 30,000 nm, and a retardation value Re(40) observed in a direction of an axis tilted from an axis perpendicular to a plane of the optical laminate toward a slow axis by 40 degrees in a plane lying perpendicular to the plane of the optical laminate and extending along the slow axis is 4,000 to 25,000 nm, the slow axis being an axis along which refractive index is highest in a plane of the film A,
condition (1): a relationship n x >n y ≥n z is satisfied, where n x denotes a refractive index in a direction of a slow axis along which refractive index is highest in a plane of the film, n y denotes a refractive index in a direction of a fast axis orthogonal to the slow axis in the plane of the film, and n z denotes a refractive index in a thickness direction of the film; and
condition (2): a relationship n x ≥n y >n z is satisfied, where n x denotes a refractive index in a direction of a slow axis along which refractive index is highest in a plane of the film, n y denotes a refractive index in a direction of a fast axis orthogonal to the slow axis in the plane of the film, and n z denotes a refractive index in a thickness direction of the film.
2. The optical laminate according to claim 1 , wherein the film C is selected from the group consisting of a polyimide film and a polyaramid film.
3. The optical laminate according to claim 1 , wherein the film A is an oriented polyester film.
4. A display device comprising a display component, a polarizer, and the optical laminate according to claim 1 in this order.
5. The display device according to claim 4 , wherein the display component is an organic EL display component.
6. The display device according to claim 5 , wherein the organic EL display component is an organic EL display component of three-color independent type.
7. The display device according to claim 4 , wherein the film C in the optical laminate is disposed so as to be closer to a viewer than the film A.
8. The display device according to claim 4 , which is a foldable display device.