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CN-116057430-B - Optical laminate and elliptical polarizing plate comprising same

CN116057430BCN 116057430 BCN116057430 BCN 116057430BCN-116057430-B

Abstract

The object of the present invention is to provide an optical laminate which is less likely to generate strain when bent, has high bending properties, and is excellent in oblique reflectance, and in particular, an optical laminate suitable for a flexible display. An optical laminate comprising, in order, a retardation film, a polarizer, and a transparent protective film, wherein the retardation film comprises a base film having a moisture permeability of 100g/m 2 /24 hours or more, and a liquid crystal cured film formed on the base film, the thickness of the liquid crystal cured film is 0.5 μm or more and 3 μm or less, and the formulae (1) and (2) below are satisfied in a single layer, the polarizer is composed of a polyvinyl alcohol resin film containing a dichroic dye, the transparent protective film has a total light transmittance of 90% or more and a 380nm transmittance of 30% or less, and the retardation film, the polarizer, and the transparent protective film are adjacent via an adhesive layer. Re (450)/Re (550) is less than or equal to 1.00 (1) 1.00 is less than or equal to Re (650)/Re (550) (2) [ in the formula, re (lambda) represents the in-plane phase difference value at the wavelength lambda ].

Inventors

  • HATANAKA NOBUYUKI
  • MURANO KOTA

Assignees

  • 住友化学株式会社

Dates

Publication Date
20260505
Application Date
20210810
Priority Date
20200907

Claims (13)

  1. 1. An optical laminate comprising a retardation film, a polarizer, and a transparent protective film in this order, The retardation film comprises a base film having a moisture permeability of 100g/m 2 /24 hours or more, and a liquid crystal cured film formed on the base film, wherein the thickness of the liquid crystal cured film is 0.5 [ mu ] m or more and 3 [ mu ] m or less, and the following formulas (1) and (2) are satisfied in a single layer: Re(450)/Re(550)≤1.00 (1) 1.00≤Re(650)/Re(550) (2) where Re (λ) represents the in-plane phase difference value at wavelength λ, The polarizer is composed of a polyvinyl alcohol resin film containing a dichromatic pigment, the transparent protective film has a total light transmittance of 90% or more and a 380nm transmittance of 30% or less, The retardation film, the polarizer and the transparent protective film are adjacent to each other with an adhesive layer interposed therebetween, The phase difference film is connected with an adhesive layer which is attached to the phase difference film and the polaroid at the side of the liquid crystal curing film, The adhesive layer has a thickness of 10nm to 5 μm, The adhesive layer is a layer formed of an adhesive selected from the group consisting of a dry curing adhesive and a chemically reactive adhesive.
  2. 2. The optical laminate according to claim 1, wherein the substrate film has a total light transmittance of 90% or more and an absolute value of a phase difference Rth (550) in a thickness direction of 550nm light is 5nm or less.
  3. 3. The optical laminate according to claim 1 or 2, wherein the retardation film has a photo-alignment film having a thickness of 10nm to 1000nm between the base film and the liquid crystal cured film.
  4. 4. The optical laminate according to claim 1 or 2, wherein the liquid crystal cured film is a film obtained by curing at least 1 compound having at least 1 maximum absorption at a wavelength of 300 to 400 nm.
  5. 5. The optical laminate according to claim 1 or 2, wherein the liquid crystal cured film satisfies the following formula (3): 100nm≤Re(550)≤170nm (3) where Re (λ) represents the in-plane phase difference value at wavelength λ.
  6. 6. The optical laminate according to claim 1 or 2, wherein the transparent protective film has a moisture permeability of 100g/m 2 /24 hours or more.
  7. 7. The optical laminate according to claim 1 or 2, wherein the adhesive layer is a layer formed of a dry curable adhesive.
  8. 8. The optical laminate of claim 7, wherein the dry curable adhesive comprises polyvinyl alcohol.
  9. 9. An optical laminate roll formed by winding the optical laminate according to any one of claims 1 to 8.
  10. 10. An elliptical polarizing plate comprising the optical laminate of any one of claims 1 to 8.
  11. 11. An organic EL display device comprising the elliptically polarizing plate according to claim 10.
  12. 12. A flexible image display device comprising the elliptically polarizing plate according to claim 10.
  13. 13. The flexible image display device of claim 12, further comprising a window and a touch sensor.

Description

Optical laminate and elliptical polarizing plate comprising same Technical Field The present invention relates to an optical laminate, a roll of the optical laminate, and an elliptical polarizing plate and an organic EL display device each including the optical laminate. Background Elliptical polarizers are optical members formed by laminating a polarizing plate and a retardation plate, and are used to prevent reflection of light at electrodes constituting an organic EL image display device or the like, for example, in such devices that display an image in a planar state. As a retardation plate constituting the elliptical polarizing plate, a so-called λ/4 plate is generally used. As such a retardation plate, a retardation plate using a liquid crystal cured film produced by coating a polymerizable liquid crystal compound on a substrate and curing the compound is known (patent document 1). Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2011-207765 Disclosure of Invention Problems to be solved by the invention In recent years, there is a demand for flexibility of a display, and it is considered that an elliptical polarizing plate having high flexibility and reduced thickness is required. The retardation film obtained by curing the polymerizable liquid crystal compound as described in reference 1 is suitable for a flexible display from the viewpoint of achieving a thin shape, and an elliptical polarizing plate (film) can be produced by transferring a retardation plate (film) formed from such a liquid crystal cured film to a polarizing plate via a pressure-sensitive adhesive. However, the inventors of the present application found that when a pressure-sensitive adhesive is used to transfer a retardation plate formed of a liquid crystal cured film, strain is likely to occur at a bending point when an elliptical polarizing plate formed therefrom is bent, and thus streak-like defects and an increase in light reflectance (oblique reflectance) from an oblique direction are generated. The object of the present invention is to provide an optical laminate which is less likely to generate strain when bent, has high bending properties, and is excellent in oblique reflectance, and in particular, an optical laminate suitable for a flexible display. Means for solving the problems The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present application. That is, the present application includes the following modes. [1] An optical laminate comprising a retardation film, a polarizer, and a transparent protective film in this order, The retardation film comprises a base film having a moisture permeability of 100g/m 2/24 hours or more, and a liquid crystal cured film formed on the base film, wherein the thickness of the liquid crystal cured film is 0.5 [ mu ] m or more and 3 [ mu ] m or less, and the liquid crystal cured film satisfies the following formulas (1) and (2) in a single layer: Re(450)/Re(550)≤1.00 (1) 1.00≤Re(650)/Re(550) (2) wherein Re (lambda) represents the in-plane phase difference value at the wavelength lambda, The polarizer is composed of a polyvinyl alcohol resin film containing a dichromatic pigment, the transparent protective film has a total light transmittance of 90% or more and a 380nm transmittance of 30% or less, The retardation film, the polarizer, and the transparent protective film are adjacent to each other with an adhesive layer interposed therebetween. [2] The optical laminate according to the above [1], wherein the total light transmittance of the base film is 90% or more, and the absolute value of the phase difference Rth (550) in the thickness direction of 550nm light is 5nm or less. [3] The optical laminate according to the above [1] or [2], wherein the retardation film has a photo-alignment film having a thickness of 10nm to 1000nm between the base film and the liquid crystal cured film. [4] The optical laminate according to any one of [1] to [3], wherein the liquid crystal cured film is a film obtained by curing at least 1 compound having at least 1 maximum absorption at a wavelength of 300 to 400 nm. [5] The optical laminate according to any one of the above [1] to [4], wherein the liquid crystal cured film satisfies the following formula (3): 100nm≤Re(550)≤170nm (3) In the formula, re (λ) represents an in-plane phase difference value at the wavelength λ. [6] The optical laminate according to any one of the above [1] to [5], wherein the transparent protective film has a moisture permeability of 100g/m 2/24 hours or more. [7] The optical laminate according to any one of the above [1] to [6], wherein the adhesive layer is a layer formed of a dry curable adhesive. [8] The optical laminate according to the above [7], wherein the dry curable adhesive comprises polyvinyl alcohol. [9] The optical laminate according to any one of the above [1] to [8], wherein the retardation film i