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US-12619009-B2 - Optical laminate and article

US12619009B2US 12619009 B2US12619009 B2US 12619009B2US-12619009-B2

Abstract

This optical laminate contains a transparent substrate, an optical functional layer and an antifouling layer laminated in that order, wherein when a light with a wavelength of 380 nm to 780 nm from a standard light source D65 is incident upon the optical laminate at an incident angle within a range from 5° to 50° relative to the surface, the a* value and the b* value in the CIE-Lab color system of the reflected light are within the same quadrant of the a*b* plane.

Inventors

  • Tomoaki Kobayashi

Assignees

  • DEXERIALS CORPORATION

Dates

Publication Date
20260505
Application Date
20211125
Priority Date
20201127

Claims (12)

  1. 1 . An optical laminate comprising: a transparent substrate; an optical functional layer; and an antifouling layer, laminated in that order, wherein when a light with a wavelength of 380 nm to 780 nm from a standard light source D65 is incident upon the optical laminate at an incident angle within a range from 5° to 50° relative to a surface of the optical laminate, an a* value and a b* value in a CIE-Lab color system of a reflected light are within a same quadrant of the a*b* plane, and a maximum value of a difference between reflectance values when the light is incident at an incident angle of 10°, 20°, 30°, 40° and 50° relative to the surface, and a reflectance when the light is incident at an incident angle of 5°, expressed as an absolute value, is 1% or less.
  2. 2 . The optical laminate according to claim 1 , wherein the a* value and the b* value of the reflected light when the light is incident at an incident angle within a range from 5° to 50° relative to the surface are both less than zero.
  3. 3 . The optical laminate according to claim 1 , wherein the reflected light when the light is incident at an incident angle within a range from 5° to 50° relative to the surface has a ΔE*ab value represented by formula (1) of 10 or less: Δ E*ab =√{square root over (Δ L* 2 +Δa* 2 +Δb* 2 )} Formula (1) wherein in formula (1), ΔE*ab represents an amount of change in an L* value and the a* value and b* value in the CIE-Lab color system, ΔL* represents a maximum value of a difference between the L* values of the reflected light when the light is incident at an incident angle of 10°, 20°, 30°, 40° and 50°, and the L* value of the reflected light when the light is incident at an incident angle of 5°, Δa* represents a maximum value of a difference between the a* values of the reflected light when the light is incident at an incident angle of 10°, 20°, 30°, 40° and 50°, and the a* value of the reflected light when the light is incident at an incident angle of 5°, and Ab* represents a maximum value of a difference between the b* values of the reflected light when the light is incident at an incident angle of 10°, 20°, 30°, 40° and 50°, and the b* value of the reflected light when the light is incident at an incident angle of 5°.
  4. 4 . The optical laminate according to claim 1 , wherein the optical functional layer is composed of a laminate comprising a low refractive index material layer and a high refractive index material layer formed from a material with a higher refractive index than the low refractive index material layer laminated in an alternating arrangement, a first high refractive index material layer formed from the high refractive index material layer and having a thickness of at least 7.5 nm is disposed on the transparent substrate side of the laminate, a first low refractive index material layer formed from the low refractive index material layer and having a thickness of 27 nm to 37 nm is disposed in contact with the first high refractive index material layer, and a second low refractive index material layer formed from the low refractive index material layer and having a thickness of 85 nm to 103 nm is disposed on the antifouling layer side of the laminate.
  5. 5 . The optical laminate according to claim 4 , wherein a second high refractive index material layer formed from the high refractive index material layer and having a thickness of at least 105 nm to 120 nm is disposed between the first low refractive index material layer and the second low refractive index material layer, and the optical functional layer is composed of four layers: the first high refractive index material layer, the first low refractive index material layer, the second high refractive index material layer, and the second low refractive index material layer.
  6. 6 . The optical laminate according to claim 1 , further comprising an adhesive layer between the transparent substrate and the optional functional layer, wherein the adhesive layer comprises at least one metal compound selected from the group consisting of a metal, an alloy, a metal oxide, a metal fluoride, a metal sulfide, and a metal nitride.
  7. 7 . The optical laminate according to claim 6 , wherein the adhesive layer comprises a metal oxide in an oxygen-deficient state.
  8. 8 . The optical laminate according to claim 6 , further comprising a hard coat layer between the transparent substrate and the adhesive layer.
  9. 9 . An article comprising the optical laminate according to claim 1 .
  10. 10 . The article according to claim 9 , further comprising an image display device, wherein the optical laminate is provided on a surface of the image display device.
  11. 11 . The optical laminate according to claim 1 , wherein the absolute value of the a* value is not more than 10.0 and the absolute value of the b* value is not more than 10.0, when light is incident at an incident angle of 5° to 50°.
  12. 12 . The optical laminate according to claim 1 , wherein the absolute value of the a* value is not more than 5.0 and the absolute value of the b* value is not more than 6.0, when light is incident at an incident angle of 5° to 50°.

Description

TECHNICAL FIELD The present invention relates to an optical laminate and an article. Priority is claimed on Japanese Patent Application No. 2020-196902, filed Nov. 27, 2020, the content of which is incorporated herein by reference. BACKGROUND ART Image display devices such as flat panel displays (FPD) are widely used in mobile telephones, smart phones, and car navigation devices and the like. In conventional image display devices, it is desirable to suppress any color irregularity caused by viewing angle. For example, Patent Document 1 discloses an anti-reflective film for which the luminous reflectance when a light A with a wavelength of 380 nm to 780 nm from a standard light source D65 is incident upon the film at an incident angle of 5° is not more than 0.5%, and for which regular reflection light generated when the incident angle of the light A on the film is varied within a range from 5° to 50° exhibits a ratio of the difference between the maximum value and the minimum value of the b* value in the CIE-Lab color system relative to the difference between the maximum value and the minimum value of the a* value in the CIE-Lab color system (difference of b* value/difference of a* value) that is 2 or greater. CITATION LIST Patent Document [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2019-28364 SUMMARY OF INVENTION Technical Problem Optical laminates such as anti-reflective films installed on image display devices preferably cause no visible color irregularities, even when the viewing angle is altered for the image display device on which the optical laminate is installed. However, with conventional optical laminates, color irregularities (differences in color tone) have sometimes been visible when the viewing angle is changed for the image display device on which the optical laminate is installed. Accordingly, for optical laminates installed on image display devices, it is desirable that color irregularities are difficult to visually detect when the viewing angle for the image display device is altered. The present invention has been developed in light of the above circumstances, and has an object of providing an optical laminate which is provided on an article, and for which color irregularities are difficult to visually detect even when the viewing angle of the article is altered. Further, the present invention also has an object of providing an article that includes the optical laminate of the present invention, and exhibits little color irregularity when the viewing angle is altered. Solution to Problem In order to achieve the above objects, this invention proposes the following aspects. [1] An optical laminate containing a transparent substrate, an optical functional layer and an antifouling layer laminated in that order, wherein when a light with a wavelength of 380 nm to 780 nm from a standard light source D65 is incident upon the optical laminate at an incident angle within a range from 5° to 50° relative to the surface, the a* value and the b* value in the CIE-Lab color system of the reflected light are within the same quadrant of the a*b* plane. [2] The optical laminate according to [1], wherein the a* value and the b* value of the reflected light when the light is incident at an incident angle within a range from 5° to relative to the surface are both less than zero.[3] The optical laminate according to [1] or [2], wherein the maximum value of the difference between the reflectance values when the light is incident at an incident angle of 10°, 20°, 30°, 40° and 50° relative to the surface, and the reflectance when the light is incident at an incident angle of 5°, expressed as an absolute value, is 1% or less.[4] The optical laminate according to any one of [1] to [3], wherein the reflected light when the light is incident at an incident angle within a range from 5° to 50° relative to the surface has a ΔE*ab value represented by formula (1) shown below of 10 or less. [Formula 1] ΔE*ab=√{square root over (ΔL*2+Δa*2+Δb*2)}  Formula (1) (In formula (1), ΔE*ab represents the amount of change in the L* value and the aforementioned a* value and b* value in the CIE-Lab color system. ΔL* represents the maximum value of the difference between the L* values of the reflected light when the light is incident at an incident angle of 10°, 20°, 30°, 40° and 50°, and the L* value of the reflected light when the light is incident at an incident angle of 5°. Δa* represents the maximum value of the difference between the a* values of the reflected light when the light is incident at an incident angle of 10°, 20°, 30°, 40° and 50°, and the a* value of the reflected light when the light is incident at an incident angle of 5°. Δb* represents the maximum value of the difference between the b* values of the reflected light when the light is incident at an incident angle of 10°, 20°, 30°, 40° and 50°, and the b* value of the reflected light when the light is incident