Optical laminate and polarizing plate, image display panel, and image display device using said optical laminate

Abstract

Provided is an optical laminate that reduces blue light, has excellent scratch resistance and adhesion, and is capable of suppressing reduction in luminance. The optical laminate includes a primer layer containing a benzotriazole-based compound between a base material and a hard coat layer, and satisfies conditions 1-3. Condition 1: The spectral transmittance at a wavelength of 410 nm is less than 1.0%, the spectral transmittance at a wavelength of 450 nm is 15.0%-85.0%, and the spectral transmittance at a wavelength of 490 nm is 85.0% or more. Condition 2: The average indentation hardness of a cross section of the primer layer at a position 1.0 μm in the thickness direction from the interface between the hard coat layer and the primer layer is 190 MPa or more. Condition 3: When the adhesion of the primer layer and the hard coat layer to the base material is evaluated by the cross-cut method of JIS K5600-5-6: 1999, the classification of the evaluation is 0 or 1.

Description

Optical laminate, and polarizing plate, image display panel, and image display device using said optical laminate

[0001] The present disclosure relates to an optical laminate, and a polarizing plate, an image display panel, and an image display device using the optical laminate.

[0002] Light-emitting diodes (hereinafter referred to as "LEDs") are sometimes used as backlight sources for image display devices such as personal computers and tablets. LEDs strongly emit light known as blue light. Blue light has a wavelength of 380 nm or more and 495 nm or less, and has properties similar to ultraviolet light and strong energy. For this reason, it is said that when blue light reaches the human retina, it can cause problems such as retinal damage, eye fatigue, and adverse effects on sleep.

[0003] As a method for solving the problem of blue light, Japanese Patent Laid-Open No. 2007-149999 proposes glasses that protect the eyes from blue light. However, the method of Japanese Patent Laid-Open No. 2007-149999 lacks convenience because the glasses are always required.

[0004] Another possible method for solving the problem of blue light is to incorporate an ultraviolet absorber into an optical laminate used in an image display device. Patent Document 2 proposes an optical laminate containing an ultraviolet absorber and having a spectral transmittance adjusted to a predetermined range.

[0005] JP 2007-93927 A Japanese Patent No. 6696562 A

[0006] The optical laminate of Patent Document 2 aims to reduce blue light by making the spectral transmittance at a wavelength of 410 nm less than 10%, etc. However, the design of the optical laminate of Patent Document 2 sometimes fails to sufficiently reduce blue light.

[0007] Furthermore, optical laminates are desired to have good scratch resistance to prevent scratches during production and use. However, adding an ultraviolet absorber to a layer constituting the optical laminate may reduce the scratch resistance of the optical laminate. The optical laminate of Patent Document 2 does not consider the compatibility of blue light reduction and scratch resistance by adding an ultraviolet absorber. Furthermore, if the hardness of the functional layer formed on the substrate is increased to improve the scratch resistance of the optical laminate, the adhesion of the functional layer may decrease. "Adhesion of the functional layer" includes adhesion between the substrate and the functional layer, and adhesion between functional layers when the functional layer is multilayered. The optical laminate of Patent Document 2 does not consider the balance between blue light reduction by adding an ultraviolet absorber, scratch resistance, and adhesion. Furthermore, the optical laminate is required to reduce blue light without impairing the brightness of the image display device.

[0008] An object of the present disclosure is to provide an optical laminate that reduces blue light, has excellent scratch resistance and adhesion, and can suppress a decrease in brightness, as well as a polarizing plate, an image display panel, and an image display device that use the same.

[0009] The present disclosure provides the following items <1> to <4>. <1> An optical laminate having a hard coat layer on a substrate, wherein the optical laminate further includes a primer layer containing a benzotriazole-based compound between the substrate and the hard coat layer, and satisfies the following conditions 1 to 3. Condition 1: The optical laminate has a spectral transmittance at a wavelength of 410 nm of less than 1.00%, a spectral transmittance at a wavelength of 450 nm of 15.00% or more but less than 85.00%, and a spectral transmittance at a wavelength of 490 nm of 85.00% or more. Condition 2: The average indentation hardness of a cross section of the primer layer at a position 1.0 μm in the thickness direction from the interface between the hard coat layer and the primer layer is 190 MPa or more. Condition 3: When the adhesion between the primer layer and the hard coat layer in the optical laminate is evaluated by the cross-cut method of JIS K5600-5-6:1999, the evaluation result is classified as 0 or 1. <2> A polarizing plate having a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer, wherein one of the first transparent protective plate and the second transparent protective plate is the optical laminate according to <1>, and the surface of the optical laminate facing the hard coat layer faces the side opposite to the polarizer. <3> An image display panel having a display element and an optical film arranged on the light emission surface side of the display element, wherein the optical film includes the optical laminate according to <4>, and the surface of the optical laminate facing the hard coat layer faces the side opposite to the display element. <4> An image display device including the image display panel according to <3>.

[0010] The optical laminate of the present disclosure, and the polarizing plate, image display panel, and image display device using the same can reduce blue light, improve scratch resistance and adhesion, and suppress a decrease in the brightness of the image display device.

[0011] 1 is a schematic cross-sectional view showing an embodiment of an optical laminate according to the present disclosure; 2 is a cross-sectional view showing an embodiment of an image display panel according to the present disclosure;

[0012] Hereinafter, embodiments of the present disclosure will be described.

[0013] [Optical Laminate] The optical laminate of the present disclosure is an optical laminate having a hard coat layer on a substrate, and further comprising a primer layer containing a benzotriazole-based compound between the substrate and the hard coat layer, and satisfies the following conditions 1 to 3. Condition 1: The optical laminate has a spectral transmittance at a wavelength of 410 nm of less than 1.00%, a spectral transmittance at a wavelength of 450 nm of 15.00% or more but less than 85.00%, and a spectral transmittance at a wavelength of 490 nm of 85.00% or more. Condition 2: The average indentation hardness of a cross section of the primer layer at a position 1.0 μm in the thickness direction from the interface between the hard coat layer and the primer layer is 190 MPa or more. Condition 3: When the adhesion between the primer layer and the hard coat layer in the optical laminate is evaluated by the cross-cut method of JIS K5600-5-6:1999, the evaluation result is classified as 0 or 1.

[0014] Fig. 1 is a schematic cross-sectional view of the cross-sectional shape of an optical laminate 100 according to the present disclosure. The optical laminate 100 of Fig. 1 has a hard coat layer 30 on a substrate 10. The optical laminate 100 of Fig. 1 has a primer layer 20 between the substrate 10 and the hard coat layer 30. Fig. 1 is a schematic cross-sectional view. That is, the scale of each layer constituting the optical laminate 100 is simplified for ease of illustration and differs from the actual scale. The same applies to Fig. 2.

[0015] The optical laminate of the present disclosure is not limited to the layer configuration shown in Fig. 1. For example, the optical laminate of the present disclosure may have other layers not shown in Fig. 1.

[0016] <Condition 1> Condition 1 specifies the spectral transmittance of the optical laminate. Specifically, it specifies that the spectral transmittance at a wavelength of 410 nm is less than 1.00%, the spectral transmittance at a wavelength of 450 nm is 15.00% or more and less than 85.00%, and the spectral transmittance at a wavelength of 490 nm is 85.00% or more.

[0017] If the spectral transmittance at a wavelength of 410 nm is 1.00% or more, the reduction of blue light will be insufficient. The spectral transmittance at a wavelength of 410 nm is preferably 0.80% or less, more preferably 0.60% or less, and even more preferably 0.40% or less. The lower limit of the spectral transmittance at a wavelength of 410 nm is not particularly limited. The lower limit of the spectral transmittance at a wavelength of 410 nm is usually 0.005% or more, preferably 0.01% or more. Preferred ranges of the spectral transmittance at a wavelength of 410 nm include 0.005% or more and less than 1.00%, 0.005% or more and less than 0.80%, 0.005% or more and less than 0.60%, 0.005% or more and less than 0.40%, 0.01% or more and less than 1.00%, 0.01% or more and less than 0.80%, 0.01% or more and less than 0.60%, and 0.01% or more and less than 0.40%.

[0018] If the spectral transmittance at a wavelength of 450 nm is less than 15.00%, the brightness of the image display device will decrease. If the spectral transmittance at a wavelength of 450 nm is 85.00% or more, the reduction of blue light will be insufficient. The lower limit of the spectral transmittance at a wavelength of 450 nm is preferably 17.00% or more, more preferably 19.00% or more, and even more preferably 20.00% or more. The upper limit of the spectral transmittance at a wavelength of 450 nm is preferably 83.00% or less, more preferably 81.00% or less, and even more preferably 79.00% or less. Preferred embodiments of the spectral transmittance at a wavelength of 450 nm include 15.00% or more and less than 85.00%, 15.00% or more and less than 83.00%, 15.00% or more and less than 81.00%, 15.00% or more and less than 79.00%, 17.00% or more and less than 85.00%, 17.00% or more and less than 83.00%, 17.00% or more and less than 81.00%, and 17.00% or more and less than 85.00%. Examples include 79.00% or less, 19.00% or more but less than 85.00%, 19.00% or more but less than 83.00%, 19.00% or more but less than 81.00%, 19.00% or more but less than 79.00%, 20.00% or more but less than 85.00%, 20.00% or more but less than 83.00%, 20.00% or more but less than 81.00%, and 20.00% or more but less than 79.00%.

[0019] If the spectral transmittance at a wavelength of 490 nm is less than 85.00%, the brightness of the image display device will decrease. The spectral transmittance at a wavelength of 490 nm is preferably 87.00% or more, and more preferably 90.00% or more. The upper limit of the spectral transmittance at a wavelength of 490 nm is not particularly limited. The upper limit of the spectral transmittance at a wavelength of 490 nm is usually 96.00% or less, preferably 95.00% or less. Preferred ranges of the spectral transmittance at a wavelength of 490 nm include 85.00% or more and 96.00% or less, 85.00% or more and 95.00% or less, 87.00% or more and 96.00% or less, 87.00% or more and 95.00% or less, 90.00% or more and 95.00% or less.

[0020] In order to reduce blue light and to easily suppress a decrease in the brightness of an image display device, the optical laminate preferably has a spectral transmittance value that gradually increases from a wavelength of 410 nm to a wavelength of 490 nm.

[0021] When the spectral transmittance at a wavelength of 455 nm is defined as X% and the spectral transmittance at a wavelength of 445 nm as Y%, the optical laminate preferably has X-Y of 15.00% or more. An X-Y of 15.00% or more means that the light transmittance increases sharply at wavelengths of around 450 nm. Therefore, by setting X-Y to 15.00% or more, blue light can be reduced and a decrease in the brightness of the image display device can be easily suppressed. X-Y is more preferably 20.00% or more, and even more preferably 25.00% or more. The upper limit of X-Y is not particularly limited. The upper limit of X-Y is usually 50.00% or less, preferably 38.00% or less. Preferred embodiments of the range of X-Y include 15.00% or more and 50.00% or less, 15.00% or more and 38.00% or less, 20.00% or more and 50.00% or less, 20.00% or more and 38.00% or less, 25.00% or more and 50.00% or less, and 25.00% or more and 38.00% or less.

[0022] The optical laminate of the present disclosure preferably has an average spectral transmittance of 1.00% or more and 40.00% or less at a wavelength of more than 410 nm and less than 450 nm, and more preferably 2.00% or more and 28.00% or less. The optical laminate of the present disclosure preferably has an average spectral transmittance of 64.00% or more and 90.00% or less at a wavelength of more than 450 nm and less than 490 nm, and more preferably 70.00% or more and 89.00% or less. The optical laminate of the present disclosure preferably has an average spectral transmittance of 80.00% or more and more preferably 85.00% or more at a wavelength of more than 490 nm and less than 780 nm. The optical laminate of the present disclosure preferably has a maximum spectral transmittance of 85.0% or more and 96.0% or less, and more preferably 87.0% or more and 95.0% or less at a wavelength of more than 410 nm and less than 780 nm.

[0023] The spectral transmittance of the optical laminate can be adjusted by the absorption characteristics of the benzotriazole-based compound in the primer layer, the content of the compound, the thickness of the primer layer, etc. A detailed adjustment method will be described in the embodiment of the primer layer.

[0024] In this specification, the light incident surface when measuring the spectral transmittance is the surface on the substrate side. The wavelength interval for measuring the spectral transmittance is 5 nm or less. The spectral transmittance can be measured using a general-purpose measuring device.

[0025] In this specification, unless otherwise specified, measurements of spectral transmittance, nanoindenter hardness, etc. are performed at a temperature of 23±5°C and a relative humidity of 40% to 65%. Before starting each measurement, the target sample is exposed to the above atmosphere for 30 minutes to 60 minutes before the measurement.

[0026] <Condition 2> Condition 2 stipulates that the average indentation hardness of the cross section of the primer layer at a position 1.0 μm from the interface between the hard coat layer and the primer layer in the thickness direction is 190 MPa or more.

[0027] Under condition 2, the indentation hardness of the cross section of the primer layer is measured at a position 1.0 μm from the interface between the hard coat layer and the primer layer in the thickness direction. The symbol X in FIG. 1 corresponds to the interface between the hard coat layer and the primer layer. Under condition 2, the indentation hardness of the cross section of the primer layer is measured at a position 1.0 μm from the interface in the thickness direction.

[0028] Even if the hard coat layer is hardened, if the layer adjacent to the hard coat layer is soft, the scratch resistance of the optical laminate cannot be improved. Failure to satisfy condition 2 means that the primer layer is not hard, but soft. Therefore, if condition 2 is not satisfied, the scratch resistance of the optical laminate cannot be improved even if the hard coat layer is hardened.

[0029] The average indentation hardness under condition 2 is preferably 195 MPa or more, and more preferably 200 MPa or more. If the average indentation hardness under condition 2 is too large, the adhesion between the primer layer and the hard coat layer may decrease, or cracks may occur during processing of the optical laminate. Therefore, the average indentation hardness under condition 2 is preferably 400 MPa or less, more preferably 350 MPa or less, and even more preferably 300 MPa or less. Examples of suitable ranges for the average indentation hardness under condition 2 include 190 MPa or more and 400 MPa or less, 190 MPa or more and 350 MPa or less, 190 MPa or more and 300 MPa or less, 195 MPa or more and 400 MPa or less, 195 MPa or more and 350 MPa or less, 195 MPa or more and 300 MPa or less, 200 MPa or more and 400 MPa or less, 200 MPa or more and 350 MPa or less, and 200 MPa or more and 300 MPa or less.

[0030] In this specification, the average indentation hardness under condition 2 is the average value of the eight measured values ​​obtained by excluding the maximum and minimum values ​​from the ten measured values.

[0031] The indentation hardness of the cross section of the primer layer is measured by preparing a sample in which the cross section perpendicular to the thickness direction of the optical laminate is exposed. The sample is prepared by steps X1 and X2.

[0032] X1: The optical laminate is cut to a desired size to prepare a cut sample, and then the cut sample is embedded in resin to prepare an embedded sample. The cut sample is a strip measuring 10 mm long x 3 mm wide. The embedding resin is epoxy resin. The embedded sample is obtained by placing the cut sample in a silicon embedding plate, pouring in the embedding resin, hardening the embedding resin, and then removing the cut sample and the embedding resin encasing it from the silicon embedding plate. The embedded sample is block-shaped.

[0033] X2: The block-shaped embedded sample is cut vertically to prepare a sliced ​​sample in which a vertical cross section in the thickness direction of the optical laminate is exposed. The embedded sample is cut with a microtome using a glass knife and a diamond knife.

[0034] The indentation hardness is measured by vertically pressing a Berkovich indenter (material: triangular diamond pyramid) into a predetermined position on the cross section of the sample. The indentation hardness is preferably measured under the following conditions. <Measurement conditions> Indenter used: Berkovich indenter Indentation conditions: Displacement control method Maximum indentation depth: 200 nm Load application time: 20 seconds (speed: 10 nm / sec) Holding time: Hold at maximum indentation depth for 5 seconds Load unloading time: 20 seconds (speed: 10 nm / sec)

[0035] The indentation hardness is calculated as follows. First, the indentation depth h (nm) corresponding to the indentation load F (N) is continuously measured, and a load-displacement curve is created. The created load-displacement curve is analyzed, and the maximum indentation load F ｍａｘ (N) is the projected area A where the indenter is in contact with the plastic film. ｐ (mm ２ ) is divided by the indentation hardness H ＩＴ is calculated (the following formula (1)). ＩＴ =Fｍａｘ / A ｐ …(1) “A ｐ " is the projected contact area corrected for indenter tip curvature in the standard manner for the instrument.

[0036] To facilitate satisfaction of condition 2, it is preferable to implement one or more measures selected from the following (A1) to (A3). Details of (A1) to (A3) will be explained in the embodiment of the primer layer. (A1) Prevent excessive penetration of the primer layer coating liquid into the substrate. (A2) Use a polymer of a benzotriazole compound as the benzotriazole compound. (A3) Use a cured product of an ionizing radiation-curable resin composition as the binder resin of the primer layer.

[0037] <Condition 3> Condition 3 stipulates that when the adhesion between the primer layer and the hard coat layer in the optical laminate is evaluated by the cross-cut method of JIS K5600-5-6:1999, the evaluation classification is 0 or 1.

[0038] The cross-cut method of JIS K5600-5-6:1999 provides six rating classifications from 0 to 5. Rating 0 is the best rating and rating 5 is the worst. The details of classifications 0, 1 and 2 are as follows: Class 0: The edges of the cuts are completely smooth and there is no peeling at any of the grid squares. Class 1: Small peeling of the coating at the intersections of the cuts. The affected area of ​​the cross-cuts is clearly not more than 5%. Class 2: The coating has peeled along the edges and / or at the intersections of the cuts. The affected area of ​​the cross-cuts is clearly more than 5% but not more than 15%.

[0039] In this specification, the cross-cut method of JIS K5600-5-6:1999 is performed with a cut interval of 1 mm. The side where the cuts are made is the hard coat layer side of the optical laminate. The cuts are made so as to penetrate the hard coat layer and the primer layer and reach the surface of the substrate.

[0040] Satisfying condition 3 means that in the optical laminate, both the adhesion between the substrate and the primer layer and the adhesion between the primer layer and the hard coat layer are good. In condition 3, the classification by the cross-cut method is preferably 0.

[0041] To facilitate satisfaction of condition 3, it is preferable to implement one or more measures selected from the following (B1) to (B3): (B1) Permeating the primer layer coating liquid into the substrate; (B2) Inducing a crosslinking reaction at the interface between the primer layer and the hard coat layer; (B3) Making the hardness of the primer layer neither too hard nor too soft. (If the hardness of the primer layer is too hard, the adhesion between the primer layer and the hard coat layer decreases, making it difficult to satisfy condition 3. If the hardness of the primer layer is too soft, the primer layer is more susceptible to cohesive failure, making it difficult to satisfy condition 3.)

[0042] <Substrate> The substrate is preferably one that has optical transparency, smoothness, heat resistance, and excellent mechanical strength. Examples of such substrates include plastic films such as polyester, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, polyurethane, and amorphous olefin (Cycloolefin Polymer: COP). The substrate may also be one in which two or more plastic films are bonded together.

[0043] Among the above substrates, polyester films such as polyethylene terephthalate and polyethylene naphthalate are preferred for their excellent mechanical strength and dimensional stability. Among polyester films, stretched films are preferred, with biaxially stretched films being more preferred. TAC film and acrylic film are preferred from the viewpoints of light transparency and optical isotropy. Furthermore, TAC film and acrylic film are preferred because they facilitate good adhesion between the substrate and the primer layer. TAC film is easily permeated with the components of the primer layer coating solution, which facilitates good adhesion. Acrylic film is easily permeated with the components of the primer layer coating solution, and the resin components in the acrylic film dissolve into the primer layer, which facilitates good adhesion. COP film and polyester film are preferred because of their excellent weather resistance.

[0044] Examples of raw materials for plastic films include one or more selected from "newly synthesized raw materials," "recycled raw materials," and "biomass-derived raw materials." To reduce environmental impact, it is preferable for plastic films to contain biomass-derived raw materials. Biomass-derived raw materials are raw materials derived from plants. Whether a raw material is biomass-derived can be determined by measuring radioactive carbon (C14). Atmospheric carbon dioxide contains a certain proportion of C14 (105.5 pMC), and it is known that the C14 content in plants that grow by absorbing atmospheric carbon dioxide is also approximately 105.5 pMC. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the proportion of C14 in the total carbon atoms in the raw material, it is possible to determine whether the raw material is biomass-derived. To improve mechanical strength and dimensional stability while reducing environmental impact, the substrate is preferably a polyester film containing a polyester derived from biomass-derived raw materials.

[0045] The thickness of the substrate is preferably 5 μm or more and 300 μm or less, more preferably 20 μm or more and 200 μm or less, and even more preferably 30 μm or more and 120 μm or less. When it is desired to reduce the thickness of the optical laminate, the upper limit of the thickness of the substrate is preferably 80 μm or less, more preferably 70 μm or less. The thickness of the substrate is measured using a general-purpose film thickness measuring device. An example of a film thickness measuring device is a Digimatic Standard Outside Micrometer (Mitutoyo Corporation, product number "MDC-25SX"). The thickness of the substrate may be measured at any 10 points, and the average value thereof may be the above-mentioned value.

[0046] In the configuration requirements shown in this specification, when multiple upper limit options and multiple lower limit options are shown, an embodiment can be made in which one selected from the upper limit options and one selected from the lower limit options are combined. For example, embodiments of the thickness of the above-mentioned base material include 5 μm to 300 μm, 5 μm to 200 μm, 5 μm to 120 μm, 5 μm to 80 μm, 5 μm to 70 μm, 5 μm to 20 μm, 20 μm to 300 μm, 20 μm to 200 μm, 20 μm to 120 μm, 20 μm to 80 μm, 20 μm to 70 μm, 30 μm to 300 μm, 30 μm to 200 μm, 30 μm to 120 μm, 30 μm to 80 μm, and 30 μm to 70 μm.

[0047] To improve adhesion, the surface of the substrate may be subjected to a physical treatment such as corona discharge treatment or a chemical treatment, or an easy-adhesion layer may be formed on the surface. The substrate preferably has a total light transmittance according to JIS K7361-1:1997 of 70% or more, more preferably 80% or more, and even more preferably 85% or more.

[0048] <Hard Coat Layer> The optical laminate of the present disclosure is required to have a hard coat layer on the substrate. By having a hard coat layer, the scratch resistance of the optical laminate can be easily improved. However, as will be described later, in order to improve the scratch resistance of the optical laminate, the primer layer must satisfy condition 2.

[0049] The hard coat layer preferably contains, as a main component, a cured product of a curable resin composition such as a thermosetting resin composition or an ionizing radiation-curable resin composition, and more preferably contains, as a main component, a cured product of an ionizing radiation-curable resin composition. The main component means that the hard coat layer contains 50% by mass or more of the resin components constituting the hard coat layer, preferably 70% by mass or more, and more preferably 90% by mass or more.

[0050] A thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that cures when heated. Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea-melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. In a thermosetting resin composition, a curing agent is added to the curable resin as needed.

[0051] The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as "ionizing radiation curable compound"). Examples of the ionizing radiation curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, as well as epoxy groups and oxetanyl groups. As the ionizing radiation curable compound, a compound having an ethylenically unsaturated bond group is preferred, a compound having two or more ethylenically unsaturated bond groups is more preferred, and among these, a polyfunctional (meth)acrylate compound having two or more ethylenically unsaturated bond groups is even more preferred. In other words, the hard coat layer preferably contains a cured product of a polyfunctional (meth)acrylate compound. As the polyfunctional (meth)acrylate compound, either a monomer or an oligomer can be used. Ionizing radiation refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. Usually, ultraviolet (UV) rays or electron beams (EB) are used, but other types of electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams can also be used.

[0052] The number of functional groups of the polyfunctional (meth)acrylate compound is preferably 3 or more and 8 or less, more preferably 3 or more and 6 or less. By making the number of functional groups 3 or more, it is possible to easily improve scratch resistance. By making the number of functional groups 8 or less, it is possible to easily suppress the occurrence of cracks during processing such as cutting.

[0053] The ionizing radiation curable compound preferably contains a polyfunctional (meth)acrylate compound. In other words, the hard coat layer preferably contains a cured product of a polyfunctional (meth)acrylate compound as a binder resin.

[0054] Among the polyfunctional (meth)acrylate compounds, examples of bifunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, 1,6-hexanediol diacrylate, etc. Examples of trifunctional or higher functional (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol tetra(meth)acrylate, isocyanuric acid-modified tri(meth)acrylate, etc. The above (meth)acrylate monomers may have a partially modified molecular skeleton. For example, the (meth)acrylate monomers may be used in which a part of the molecular skeleton is modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, or the like.

[0055] Examples of polyfunctional (meth)acrylate oligomers include acrylate polymers such as urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate. Urethane (meth)acrylate can be obtained, for example, by reacting a polyhydric alcohol and an organic diisocyanate with a hydroxy (meth)acrylate. Preferred epoxy (meth)acrylates include (meth)acrylates obtained by reacting a trifunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with (meth)acrylic acid, (meth)acrylates obtained by reacting a difunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with a polybasic acid and (meth)acrylic acid, and (meth)acrylates obtained by reacting a difunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with a phenol and (meth)acrylic acid.

[0056] The number average molecular weight of the polyfunctional (meth)acrylate oligomer is preferably from 500 to 3000, more preferably from 600 to 2000, and even more preferably from 700 to 1200. In this specification, the number average molecular weight and weight average molecular weight are average molecular weights measured by GPC analysis and converted into standard polystyrene.

[0057] For the purpose of adjusting the viscosity of the coating liquid for the hard coat layer, a monofunctional (meth)acrylate may be used in combination as the ionizing radiation curable compound. Examples of the monofunctional (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isobornyl (meth)acrylate. The ionizing radiation curable compounds may be used alone or in combination of two or more.

[0058] When the ionizing radiation-curable compound is an ultraviolet-curable compound, the coating liquid for the hard coat layer preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator. Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyloxime ester, α-aminoalkylphenone, thioxanthones, etc. The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing rate, and examples thereof include one or more selected from p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc.

[0059] The thickness of the hard coat layer is preferably 1.3 μm or more, more preferably 2.0 μm or more, and the upper limit is preferably 30.0 μm or less, more preferably 10.0 μm or less. By setting the thickness of the hard coat layer within the above range, it is possible to improve scratch resistance while easily suppressing the occurrence of cracks during processing such as cutting. Preferred ranges of the thickness of the hard coat layer include 1.3 μm or more and 30.0 μm or less, 1.3 μm or more and 10.0 μm or less, 2.0 μm or more and 30.0 μm or less, and 2.0 μm or more and 10.0 μm or less.

[0060] The thickness of the hard coat layer and the primer layer described below can be calculated by selecting any 20 points on a cross-sectional photograph of the optical laminate taken with a scanning transmission electron microscope and averaging the thicknesses at the 20 points.

[0061] The hard coat layer may further contain additives such as a matting agent, a leveling agent, an antifouling agent, an antistatic agent, an antioxidant, a surfactant, a dispersant, and a light stabilizer. The hard coat layer may contain an ultraviolet absorber, but in order to improve scratch resistance, it is preferable that the hard coat layer is substantially free of ultraviolet absorbers. "Substantially free of ultraviolet absorbers" means that the content of the ultraviolet absorber is 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0% by mass, of the total solid content of the hard coat layer.

[0062] In order to facilitate good scratch resistance, the hard coat layer preferably has an average indentation hardness of 300 MPa or more at a position 1.0 μm in the thickness direction from the interface between the hard coat layer and the primer layer. The average indentation hardness of the cross section of the hard coat layer is more preferably 310 MPa or more, and even more preferably 320 MPa or more. If the average indentation hardness of the cross section of the hard coat layer is too large, cracks may occur during processing of the optical laminate. For this reason, the average indentation hardness of the cross section of the hard coat layer is preferably 500 MPa or less, and more preferably 430 MPa or less. In order to facilitate the average indentation hardness of the cross section of the hard coat layer being within the above range, it is preferable that the number of functional groups of the polyfunctional (meth)acrylate compound be within the above range. Examples of suitable ranges for the average cross-sectional indentation hardness of the hard coat layer include 300 MPa or more and 500 MPa or less, 300 MPa or more and 430 MPa or less, 310 MPa or more and 500 MPa or less, 310 MPa or more and 430 MPa or less, 320 MPa or more and 500 MPa or less, and 320 MPa or more and 430 MPa or less.

[0063] In this specification, the average indentation hardness of the cross section of the hard coat layer is the average value of the 8 measured values ​​obtained by excluding the maximum and minimum values ​​from the 10 measured values. The indentation hardness of the cross section of the hard coat layer is measured using a sample prepared by exposing the cross section perpendicular to the thickness direction of the optical laminate. The sample is prepared by steps X1 and X2 above. The measurement conditions for measuring the indentation hardness of the cross section of the hard coat layer are the same as the measurement conditions for the indentation hardness of the cross section of the primer layer described above.

[0064] The hard coat layer can be formed, for example, by applying a coating liquid for hard coat layer containing materials for forming the hard coat layer and a solvent onto the primer layer, drying it, and then irradiating it with ionizing radiation as necessary.

[0065] <Primer Layer> The optical layered body of the present disclosure is required to include a primer layer containing a benzotriazole-based compound between the substrate and the hard coat layer.

[0066] When a UV absorber such as a benzotriazole-based compound is contained in a hard coat layer, it is difficult to improve the scratch resistance of the optical laminate. Also, when a UV absorber such as a benzotriazole-based compound is contained in a substrate, the UV absorber may flow out of the substrate when a primer layer is applied to the substrate, or the UV absorber may bleed out over time from the surface of the substrate opposite to the surface on which the primer layer is formed. For this reason, the optical laminate of the present disclosure contains a benzotriazole-based compound in the primer layer.

[0067] The benzotriazole-based compound is preferably a compound that satisfies the following conditions Y1 and Y2 regarding its absorption peak: (Condition Y1) A compound that has a first absorption peak at a wavelength of 380 nm or more and 410 nm or less. (Condition Y2) A compound that does not have an absorption peak at a wavelength of 490 nm or less that is longer than the first absorption peak.

[0068] By using a benzotriazole-based compound that satisfies the above conditions Y1 and Y2, it is possible to more easily satisfy the spectral transmittance requirements for the three wavelengths in Condition 1. Furthermore, by using a benzotriazole-based compound that satisfies the above conditions Y1 and Y2, it is possible to more easily increase the spectral transmittance value from a wavelength of 410 nm to a wavelength of 490 nm. Furthermore, by using a benzotriazole-based compound that satisfies the above conditions Y1 and Y2, it is possible to more easily achieve X-Y of 15.00% or more.

[0069] In this specification, the absorption peak means the wavelength at which the absorbance changes from increasing to decreasing.

[0070] In condition Y1, the position of the absorption peak is more preferably at a wavelength of 380 nm or more and 400 nm or less, and even more preferably at a wavelength of 380 nm or more and 390 nm or less.

[0071] The benzotriazole-based compound satisfying the above conditions Y1 and Y2 may further have an absorption peak in a wavelength region of less than 380 nm. An example of the benzotriazole-based compound satisfying the above conditions Y1 and Y2 is a methoquinone-type benzotriazole-based compound represented by the following general formula (1):

[0072]

[0073] In formula (1), R １ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ２ represents an alkyl group having 1 to 8 carbon atoms. ３ represents an acryloyloxyalkyl group having 1 or 2 alkyl carbon atoms, or a methacryloyloxyalkyl group having 1 or 2 alkyl carbon atoms.

[0074] Specific examples of the methoquinone-type benzotriazole compound represented by general formula (1) include 2-methacryloyloxyethyl 2-(2-hydroxy-5-methoxyphenyl)-2H-benzotriazole-5-carboxylate, 2-acryloyloxyethyl 2-(3-tert-butyl-2-hydroxy-5-methoxyphenyl)-2H-benzotriazole-5-carboxylate, and 2-methacryloyloxyethyl 2-(3-tert-butyl-2-hydroxy-5-methoxyphenyl)-2H-benzotriazole-5-carboxylate.

[0075] The benzotriazole compound of the primer layer is preferably a polymer containing a methoquinone-type benzotriazole compound. Being a polymer makes it easier to increase the indentation hardness of the primer layer. Furthermore, being a polymer makes it harder for the benzotriazole compound to bleed out of the primer layer, making it easier to improve compatibility with the crosslinking / curing component described below. Examples of the polymer include homopolymers of methoquinone-type benzotriazole compounds and copolymers of methoquinone-type benzotriazole compounds with other polymerizable monomers. Examples of other polymerizable monomers include (meth)acrylate compounds.

[0076] Examples of the (meth)acrylate compound as another polymerizable monomer include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; hydroxyl group-containing (meth)acrylate compounds such as hydroxyethyl (meth)acrylate, hydroxypropylethyl (meth)acrylate, hydroxybutyl (meth)acrylate, and caprolactone-modified hydroxy(meth)acrylate; and glycidyl (meth)acrylate.

[0077] The polymerization method for homopolymerizing or copolymerizing the methoquinone-type benzotriazole compound can be a general-purpose polymerization method such as solution polymerization, emulsion polymerization, suspension polymerization, or bulk polymerization. Additives such as a polymerization initiator used in the polymerization can be selected from general-purpose materials. The reaction temperature during the polymerization is preferably 40°C or higher and 140°C or lower.

[0078] The polymer containing the methoquinone-type benzotriazole compound preferably has a number average molecular weight of 2,000 or more and 10,000 or less, more preferably 3,000 or more and 8,000 or less, and even more preferably 4,000 or more and 6,000 or less.

[0079] The primer layer preferably contains a cured product of an ionizing radiation-curable resin composition in addition to a benzotriazole-based compound. Furthermore, as described above, the benzotriazole-based compound is preferably a polymer containing a methoquinone-type benzotriazole-based compound. That is, the primer layer more preferably contains a polymer containing a methoquinone-type benzotriazole-based compound and a cured product of an ionizing radiation-curable resin composition.

[0080] In the primer layer, the mass ratio of the polymer containing a methoquinone-type benzotriazole compound to the cured product of the ionizing radiation-curable resin composition is preferably 95:5 to 50:50, more preferably 85:15 to 55:45, and even more preferably 82:18 to 58:42. If the proportion of the polymer containing a methoquinone-type benzotriazole compound is too low, it becomes difficult to reduce blue light. If the proportion of the polymer containing a methoquinone-type benzotriazole compound is too high, the hardness of the primer layer is likely to decrease. If the proportion of the cured product of the ionizing radiation-curable resin composition is too high, the adhesion between the primer layer and the hard coat layer is likely to decrease. Therefore, by setting the mass ratio within the above range, conditions 1 to 3 can be easily satisfied.

[0081] The cured product of the ionizing radiation-curable resin composition of the primer layer is preferably a cured product of a polyfunctional (meth)acrylate compound. The number of functional groups of the polyfunctional (meth)acrylate compound is preferably 3 to 8, more preferably 3 to 6. By setting the number of functional groups to 3 or more, the hardness of the primer layer can be easily increased, making it easier to satisfy condition 2. By setting the number of functional groups to 8 or less, the hardness of the primer layer can be prevented from becoming too high, making it easier to satisfy condition 3.

[0082] The polyfunctional (meth)acrylate compound of the primer layer may be a monomer or an oligomer. Examples of the polyfunctional (meth)acrylate compound of the primer layer include the same examples as those of the polyfunctional (meth)acrylate compound of the hard coat layer.

[0083] The average indentation hardness under condition 2 can also be adjusted by the content of photopolymerization initiator and the amount of ultraviolet light irradiation. For example, the average indentation hardness under condition 2 tends to increase as the content of photopolymerization initiator relative to the ionizing radiation-curable resin composition in the primer layer coating liquid increases. Furthermore, the average indentation hardness under condition 2 tends to increase as the amount of ultraviolet light irradiation when applying and curing the primer layer coating liquid increases.

[0084] By forming both the primer layer and the hard coat layer from a coating liquid containing an ionizing radiation curable resin composition, a crosslinking reaction is more likely to occur at the interface between the primer layer and the hard coat layer, making it easier to satisfy condition 3.

[0085] The primer layer can be formed, for example, by applying a primer layer coating liquid containing a primer layer-forming material and a solvent to a substrate, drying the coating liquid, and then irradiating the substrate with ionizing radiation as needed. The coating liquid preferably has a solids content of 16% by mass or more, more preferably 18% by mass or more. A low solids content means a high solvent content in the coating liquid. A high solvent content facilitates penetration of the primer layer coating liquid into the substrate. Furthermore, polyfunctional (meth)acrylate compounds tend to penetrate the substrate more easily than benzotriazole compounds. Therefore, when the solvent content in the coating liquid is high, the polyfunctional (meth)acrylate compounds penetrate the substrate, which tends to reduce the ratio of the polyfunctional (meth)acrylate compounds to the benzotriazole compounds in the primer layer. In other words, by setting the solids content to 16% by mass or more, it is possible to easily prevent a reduction in the ratio of the polyfunctional (meth)acrylate compounds in the primer layer, making it easier to satisfy condition 2.

[0086] Examples of the solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), and cyclohexanone; ethers such as dioxane and tetrahydrofuran; aliphatic hydrocarbons such as hexane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated carbons such as dichloromethane and dichloroethane; esters such as methyl acetate, ethyl acetate, and butyl acetate; alcohols such as isopropanol, butanol, and cyclohexanol; cellosolves such as methyl cellosolve and ethyl cellosolve; glycol ethers such as propylene glycol monomethyl ether acetate; cellosolve acetates; sulfoxides such as dimethyl sulfoxide; amides such as dimethylformamide and dimethylacetamide; and mixtures thereof. The solvent is preferably selected depending on the type of substrate. For example, when the substrate is a TAC film, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, toluene, ethyl acetate, cyclohexanone, and propylene glycol monomethyl ether acetate are preferred.

[0087] The lower limit of the thickness of the primer layer is preferably 1.3 μm or more, more preferably 1.4 μm or more, and the upper limit is preferably 7.5 μm or less, more preferably 6.5 μm or less. By setting the thickness of the primer layer within the above range, it is possible to more easily satisfy the spectral transmittance requirements for the three wavelengths in Condition 1. Preferred embodiments of the thickness of the primer layer include 1.3 μm or more and 7.5 μm or less, 1.3 μm or more and 6.5 μm or less, 1.4 μm or more and 7.5 μm or less, and 1.4 μm or more and 6.5 μm or less.

[0088] The primer layer may further contain additives such as a leveling agent, an antifouling agent, an antistatic agent, an antioxidant, a surfactant, a dispersant, and a light stabilizer.

[0089] <Other Layers> The optical laminate may have layers other than the substrate, the primer layer, and the hard coat layer. Examples of the other layers include an antireflection layer, an antifouling layer, an antistatic layer, and an adhesive layer.

[0090] <Pencil Hardness> In order to enhance scratch resistance, the surface of the optical laminate on the hard coat layer side preferably has a pencil hardness of 2H or more, more preferably 3H or more.

[0091] In this specification, pencil hardness is measured in accordance with JIS K5600-5-4:1999, except for the following measurement and judgment conditions. <Measurement conditions> Load: 500 g Speed: 1.4 mm / sec <Judgment conditions> Pencil hardness measurement samples are subjected to five pencil hardness tests, and the hardness at which no appearance abnormalities such as scratches are observed four or more times is taken as the pencil hardness value of each sample. For example, if five tests are performed using a 2H pencil and no appearance abnormalities occur four times, the pencil hardness of that sample is 2H. Appearance abnormalities were checked for scratches, not discoloration.

[0092] <Optical Properties> The optical laminate preferably has a total light transmittance according to JIS K7361-1:1997 of 80% or more, more preferably 85% or more. When measuring the total light transmittance and haze, the light incident surface is the surface on the substrate side. In this specification, the total light transmittance means the average value of measurements taken at 10 locations.

[0093] The optical laminate preferably has a haze of 1.0% or less, more preferably 0.7% or less, and even more preferably 0.5% or less, according to JIS K7136:2000. By making the haze 1.0% or less, it is possible to easily improve the resolution of images. The lower limit of the haze is not particularly limited, but is usually 0.1% or more.

[0094] <Size, Shape, etc.> The optical laminate may be in the form of sheets cut to a predetermined size, or in the form of a roll obtained by winding a long sheet into a roll. The size of the sheets is not particularly limited, but the maximum diameter is approximately 2 inches to 500 inches. The "maximum diameter" refers to the maximum length when any two points on the optical laminate are connected. When the optical laminate is rectangular, the diagonal line of the rectangle is the maximum diameter. When the optical laminate is circular, the diameter of the circle is the maximum diameter. The width and length of the roll are not particularly limited, but generally, the width is approximately 500 mm to 3000 mm and the length is approximately 500 m to 5000 m. The optical laminate in roll form can be cut into sheets to fit the size of an image display device or the like. When cutting, it is preferable to exclude the ends of the roll, which have unstable physical properties. The shape of the sheets is also not particularly limited, and may be, for example, a polygonal shape such as a triangle, a rectangle, or a pentagon, a circular shape, or a random, irregular shape. More specifically, when the optical laminate is rectangular, the aspect ratio is not particularly limited as long as it does not cause any problems as a display screen, and examples include width:height ratios of 1:1, 4:3, 16:10, 16:9, and 2:1.

[0095] [Polarizing Plate] The polarizing plate of the present disclosure has a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer, wherein one of the first transparent protective plate and the second transparent protective plate is the optical laminate of the present disclosure described above, and the surface of the optical laminate facing the hard coat layer faces away from the polarizer.

[0096] The polarizing plate is used, for example, in combination with a λ / 4 retardation plate to impart anti-reflection properties. In this case, a λ / 4 retardation plate is placed on the display element of the image display device, and a polarizing plate is placed closer to the viewer than the λ / 4 retardation plate. In a liquid crystal display device, the polarizing plate is used to impart liquid crystal shutter functionality. In this case, the liquid crystal display device is arranged in the following order from the backlight side: a lower polarizing plate, a liquid crystal display element, and an upper polarizing plate, with the absorption axis of the polarizer of the lower polarizing plate and the absorption axis of the polarizer of the upper polarizing plate being orthogonal to each other. In the configuration of a liquid crystal display device, the polarizing plate of the present disclosure can be used as both the upper polarizing plate and the lower polarizing plate, and it is preferable to use the polarizing plate of the present disclosure as the upper polarizing plate. In the upper polarizing plate, it is preferable to use the optical laminate of the present disclosure as a transparent protective plate on the light exit surface side of the polarizer. In the lower polarizing plate, it is preferable to use the optical laminate of the present disclosure as a transparent protective plate on the light incident surface side of the polarizer.

[0097] <Transparent Protective Plate> The polarizing plate of the present disclosure includes the optical laminate of the present disclosure as one of the first transparent protective plate and the second transparent protective plate. When one of the first transparent protective plate and the second transparent protective plate includes the optical laminate of the present disclosure, the other transparent protective plate is preferably an optically isotropic transparent protective plate. In this specification, optically isotropic refers to an in-plane retardation of 20 nm or less, preferably 10 nm or less, and more preferably 5 nm or less. Acrylic films and triacetyl cellulose (TAC) films are likely to impart optical isotropy. When one of the first transparent protective plate and the second transparent protective plate includes the optical laminate of the present disclosure, it is preferable that the transparent protective plate on the light-emitting side includes the optical laminate of the present disclosure.

[0098] <Polarizer> Examples of polarizers include sheet-type polarizers such as polyvinyl alcohol films, polyvinyl formal films, polyvinyl acetal films, and saponified ethylene-vinyl acetate copolymer films that are dyed with iodine or the like and stretched; wire-grid polarizers made of a large number of metal wires arranged in parallel; coating-type polarizers coated with a lyotropic liquid crystal or a dichroic guest-host material; and multilayer thin-film polarizers. These polarizers may be reflective polarizers that have the function of reflecting polarized components that are not transmitted.

[0099] [Image Display Panel] The image display panel of the present disclosure is an image display panel having a display element and an optical film arranged on the light emission surface side of the display element, the optical film including the optical laminate of the present disclosure described above, and the surface of the optical laminate on the hard coat layer side being arranged to face away from the display element (see FIG. 2).

[0100] Examples of the display element include a liquid crystal display element, an EL display element such as an organic EL display element or an inorganic EL display element, a plasma display element, and an LED display element such as a micro LED display element. These display elements may have a touch panel function inside the display element. Examples of the liquid crystal display system of the liquid crystal display element include an IPS system, a VA system, a multi-domain system, an OCB system, an STN system, and a TSTN system.

[0101] The image display panel of the present disclosure may be an image display panel with a touch panel, in which case the optical laminate may be used as a component constituting the touch panel.

[0102] The size of the image display panel is not particularly limited, but the maximum diameter is about 2 inches to 500 inches. The maximum diameter means the maximum length when connecting any two points on the surface of the image display panel.

[0103] [Image Display Device] The image display device of the present disclosure includes the image display panel of the present disclosure described above.

[0104] The image display device of the present disclosure preferably further includes a drive control unit electrically connected to the image display panel, and a housing that houses the image display panel, the drive control unit, etc. When the display element is a liquid crystal display element, the image display device of the present disclosure requires a backlight. The backlight is disposed on the side opposite to the light exit surface of the liquid crystal display element.

[0105] The size of the image display device is not particularly limited, but the maximum diameter of the effective display area is approximately 2 inches or more and 500 inches or less. The effective display area of ​​an image display device is the area in which an image can be displayed. For example, if the image display device has a housing that surrounds the display element, the area inside the housing is the effective display area. The maximum diameter of the effective display area refers to the maximum length when any two points within the effective display area are connected. For example, if the effective display area is rectangular, the diagonal of the rectangle is the maximum diameter. If the effective display area is circular, the diameter of the circle is the maximum diameter.

[0106] The present disclosure includes the following items <1> to <8>. <1> An optical laminate having a hard coat layer on a substrate, wherein the optical laminate further includes a primer layer containing a benzotriazole-based compound between the substrate and the hard coat layer, and satisfies the following conditions 1 to 3. Condition 1: The optical laminate has a spectral transmittance at a wavelength of 410 nm of less than 1.00%, a spectral transmittance at a wavelength of 450 nm of 15.00% or more but less than 85.00%, and a spectral transmittance at a wavelength of 490 nm of 85.00% or more. Condition 2: The average indentation hardness of a cross section of the primer layer at a position 1.0 μm in the thickness direction from the interface between the hard coat layer and the primer layer is 190 MPa or more. Condition 3: When the adhesion between the primer layer and the hard coat layer in the optical laminate is evaluated by the cross-cut method of JIS K5600-5-6:1999, the evaluation result is classified as 0 or 1. <2> The optical laminate according to <1>, wherein the spectral transmittance of the optical laminate gradually increases from a wavelength of 410 nm to a wavelength of 490 nm. <3> The optical laminate according to <1> or <2>, wherein, when the spectral transmittance of the optical laminate at a wavelength of 455 nm is defined as X%, and the spectral transmittance of the optical laminate at a wavelength of 445 nm is defined as Y%, X-Y is 15.00% or more. <4> The optical laminate according to any one of <1> to <3>, wherein the average indentation hardness of a cross section of the hard coat layer at a position 1.0 μm in the thickness direction from the interface between the hard coat layer and the primer layer is 300 MPa or more. <5> The optical laminate according to any one of <1> to <4>, wherein the substrate is a triacetyl cellulose film or an acrylic film. <6> The optical laminate according to any one of <1> to <5>, wherein, under condition 2, the average indentation hardness of a cross section of the primer layer is 190 MPa or more and 400 MPa or less. <7> The optical laminate according to any one of <1> to <6>, wherein the thickness of the primer layer is 1.3 μm or more and 7.5 μm or less.<8> A polarizing plate having a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer, wherein one of the first transparent protective plate and the second transparent protective plate is the optical laminate according to any one of <1> to <7>, and the surface of the optical laminate facing the hard coat layer faces the side opposite to the polarizer. <9> An image display panel having a display element and an optical film arranged on the light emission surface side of the display element, wherein the optical film includes the optical laminate according to any one of <1> to <7>, and the surface of the optical laminate facing the hard coat layer faces the side opposite to the display element. <10> An image display device including the image display panel according to <9>.

[0107] Next, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to these examples. "Parts" and "%" are based on mass unless otherwise specified.

[0108] 1. Measurement and Evaluation Measurement and evaluation were performed on the optical laminates of the Examples and Comparative Examples as follows. The atmosphere during each measurement and evaluation was a temperature of 23±5°C and a relative humidity of 40% to 65%. Before starting each measurement and evaluation, the target sample was exposed to the atmosphere for 30 minutes to 60 minutes, and then measurement and evaluation were performed. The samples used for each measurement and evaluation can be prepared by cutting the optical laminates of the Examples and Comparative Examples. The cutting locations were selected from random locations after visually checking for any abnormalities such as dust or scratches.

[0109] 1-1. Spectral Transmittance The spectral transmittance of the optical laminates of the Examples and Comparative Examples was measured using a spectrophotometer (Shimadzu Corporation, product name: UV-2450). The measurement wavelength interval was 1 nm. The light source was D65. The measurements were conducted in accordance with geometric condition e of "5.4 Measurement method for transparent objects" in JIS Z8722:2009. The spectral transmittance at wavelengths of 410 nm, 450 nm, and 490 nm, as well as the maximum spectral transmittance at wavelengths of 410 nm to 780 nm, are shown in the table. The spectral transmittance at a wavelength of 455 nm is defined as X%, and the spectral transmittance at a wavelength of 445 nm is defined as Y%, and the "X-Y" is also shown in the table.

[0110] 1-2. Indentation Hardness Samples for indentation hardness measurement were prepared according to steps X1 and X2 of the specification. The silicone embedding plate X1 was manufactured by Dosaka EM Co., Ltd. The epoxy resin used for embedding X1 was a 10:1.2 mixture of Struers' "Epofix" and "Epofix Hardener" (both manufactured by the same company). The embedding resin X1 was cured by leaving it at room temperature for 12 hours. The device used to cut the block-shaped embedded sample X2 was an "Ultramicrotome EM UC7" manufactured by Leica Microsystems. When cutting the block-shaped embedded sample, a rough cut was first made with a glass knife to create a surface approximately 100 μm long x 20 μm wide, including the cross section of the coated surface (rough trimming). Finally, this surface was cut with a diamond knife under conditions of "SPEED: 1.40 mm / s" and "FEED: 80 nm," and a section floating on water was collected with a mesh. The collected section was used as a sample for indentation hardness measurement. A collodion-coated mesh (Cat. No.: 651) manufactured by Nissin EM was used. Next, a Berkovich indenter (material: diamond triangular pyramid) was pressed vertically into the cross section of the sample, and the indentation hardness was measured using a HYSITRON "TI950 TriboIndenter" measuring device and the accompanying application software (TriboScan Version 9.6.0.2) under the following conditions. The indentation hardness was measured as the first and second indentation hardnesses described below. First indentation hardness: Indentation hardness of the cross section of the primer layer at a position 1.0 μm in the thickness direction from the interface between the hard coat layer and the primer layer. Second indentation hardness: Indentation hardness of a cross section of the hard coat layer at a position 1.0 μm from the interface between the hard coat layer and the primer layer in the thickness direction.In the above measurements, before measuring the indentation hardness of each sample, an indentation test was performed using a standard sample (fused quartz (5-0098) manufactured by HYSITRON) with known indentation hardness and composite modulus, and standard alignment was performed to confirm that the indentation hardness and composite modulus obtained from the test results were within the standard values. <Measurement conditions> - Indenter used: Berkovich indenter (model number: TI-0039, manufactured by HYSITRON) - Indentation conditions: Displacement control method - Maximum indentation depth: 200 nm - Load application time: 20 seconds (speed: 10 nm / sec) - Hold time: Hold at maximum indentation depth for 5 seconds - Load unloading time: 20 seconds (speed: 10 nm / sec).

[0111] 1-3. Adhesion The adhesion of the primer layer and the hard coat layer of the optical laminates of the Examples and Comparative Examples was evaluated according to the cross-cut method of JIS K5600-5-6:1999. The cut interval was 1 mm. Those with an evaluation classification of 0 or 1 can be said to have good adhesion.

[0112] 1-4. Pencil Hardness (Abrasion Resistance) Samples were prepared by cutting the optical laminates of the Examples and Comparative Examples into pieces measuring 5 cm x 10 cm. The pencil hardness of the hard coat layer side of the samples was measured in accordance with JIS K5600-5-4:1999, except for the following measurement, heating, and evaluation conditions. A Toyo Seiki Seisakusho pencil hardness tester (product number: NP-type pencil scratch coating hardness tester) was used for the measurement. Both ends of the cut sample were attached to the base of the pencil hardness tester using mending tape (3M, product number "810-3-18"), and measurements were performed. <Measurement Conditions> Load: 500 g Speed: 1.4 mm / sec <Sample Heating> After applying a load to the sample under the above measurement conditions, the sample was heated at 100°C for 10 minutes. Immediately after heating, the pencil hardness was evaluated under the following evaluation conditions. <Judgment Criteria> The pencil hardness test was performed five times, and the hardness when no appearance abnormalities such as scratches were observed four or more times was taken as the pencil hardness value of each sample. For example, if the test was performed five times using a 2H pencil and no appearance abnormalities occurred four times, the pencil hardness of that sample was 2H. The appearance abnormalities did not include discoloration, but were checked for scratches. Dents restored by the above-mentioned heating were not counted as appearance abnormalities. A pencil hardness of 2H or more was considered to be a pass level.

[0113] 1-5. Blue Light Cut Rate Illuminance without the optical laminate was measured using a spectroradiometer (Konica Minolta, product name: CS-2000) with a liquid crystal display device manufactured by LG Electronics (product number: 49NANO86JNA) displaying white. The illuminance was measured from the front of the liquid crystal display device at a measurement distance of 500 mm. The spectroradiometer can measure illuminance for each wavelength. The blue light ratio without the optical laminate was calculated using the following formula: Blue light ratio = illuminance at a wavelength of 400 nm or more and 500 nm or less / illuminance at a wavelength of 300 nm or more and 700 nm or less. Next, the optical laminates of the examples and comparative examples were bonded to the liquid crystal display device via an optical adhesive layer (manufactured by Panac Corporation, product name "Panaclean PD-S1", thickness 50 μm) to prepare a liquid crystal display device with the optical laminate. The illuminance was measured using the spectroradiometer with the display device with the optical laminate displaying white. Then, the blue light ratio with the optical laminate was calculated using the above formula. Next, the blue light blocking rate (unit: "%)" was calculated using the following formula. A value of 15% or more is considered acceptable. Blue light blocking rate = (blue light ratio with optical laminate / blue light ratio without optical laminate) x 100

[0114] 1-6. Brightness Ratio With a liquid crystal display device manufactured by LG Electronics (product number: 49NANO86JNA) displaying white, the brightness without the optical laminate was measured using a spectroradiometer (manufactured by Konica Minolta, product name: CS-2000). The brightness was measured from the front of the liquid crystal display device at a measurement distance of 500 mm. Next, the optical laminates of the Examples and Comparative Examples were attached to the liquid crystal display device via an optical adhesive layer (manufactured by Panac Corporation, product name "Panaclean PD-S1", thickness 50 μm) to produce a liquid crystal display device with an optical laminate. With the display device with the optical laminate displaying white, the brightness was measured using the spectroradiometer. Then, the brightness ratio (unit: "%") was calculated using the following formula. A value of 96% or higher is considered acceptable. Brightness ratio = (Brightness with optical laminate / Brightness without optical laminate) × 100

[0115] 1-7. Color Difference (Δx, Δy) With a liquid crystal display device manufactured by LG Electronics (product number: 49NANO86JNA) displaying white, the x and y values ​​without the optical laminate were measured using a spectroradiometer (manufactured by Konica Minolta, product name: CS-2000). The x and y values ​​are the x and y values ​​of the Yxy color system of the Commission Internationale de l'Eclairage (CIE). Measurements were taken from the front of the liquid crystal display device at a measurement distance of 500 mm. Next, the optical laminates of the Examples and Comparative Examples were attached to the liquid crystal display device via an optical adhesive layer (manufactured by Panac Corporation, product name "Panaclean PD-S1", thickness 50 μm) to produce a liquid crystal display device with an optical laminate. With the display device with the optical laminate displaying white, the x and y values ​​were measured using the spectroradiometer. The absolute value of the difference between the x value with the optical laminate and the x value without the optical laminate was calculated, and this absolute value was designated as Δx. The absolute value of the difference between the y value with the optical laminate and the y value without the optical laminate was calculated, and this absolute value was taken as Δy. Δx and Δy of 0.190 or less are acceptable levels.

[0116] 1-8. Total Light Transmittance (Tt) and Haze (Hz) The optical laminates of the Examples and Comparative Examples were cut into 10 cm x 10 cm pieces to prepare measurement samples. Using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory), the total light transmittance of each sample according to JIS K7361-1:1997 and the haze according to JIS K7136:2000 were measured under the following conditions. In order to stabilize the light source, the power switch of the device was turned on in advance, and then calibration was performed 15 minutes or more later, without setting anything in the entrance opening where the measurement sample was to be placed. Thereafter, the measurement sample was set in the entrance opening, and the total light transmittance and haze were measured. The light incident surface during measurement was the substrate side.

[0117] 2. Synthesis of methoquinone-type benzotriazole compound A methoquinone-type benzotriazole compound of the following formula was synthesized in accordance with Synthesis Example 1 of JP 2018-177976 A.

[0118] 3. Preparation of a Copolymer Containing a Methoquinone-Type Benzotriazole Compound: A four-neck flask was equipped with a Dimroth condenser, a mercury thermometer, a nitrogen gas inlet, and a stirrer. 20 parts by weight of the compound synthesized in "2" above, 20 parts by weight of methyl methacrylate, 60 parts by weight of methyl ethyl ketone as a solvent, and 1.5 parts by weight of 2,2'-azobis-methylbutyronitrile as a polymerization initiator were added. The atmosphere in the flask was replaced with nitrogen at a nitrogen gas flow rate of 10 ml / min for 1 hour while stirring, and then the polymerization reaction was carried out under reflux at a reaction temperature of 80-86°C for 10 hours. After completion of the polymerization reaction, a solution containing a copolymer containing a methoquinone-type benzotriazole compound was obtained. The solvent was then removed using an evaporator to obtain a copolymer containing a methoquinone-type benzotriazole compound. The copolymer had a number-average molecular weight of 5271 and absorption peaks at wavelengths of 314.0 nm and 383.6 nm.

[0119] 4. Preparation of Primer Layer Coating Solution <Primer Layer Coating Solution for Examples 1 to 6, 11, and Comparative Examples 1, 2, and 7> 80 parts by weight of the copolymer obtained in "3" above and 20 parts by weight of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., product name: PET-30) as a polyfunctional (meth)acrylate compound were weighed out. Furthermore, 10 parts by weight of a photopolymerization initiator (manufactured by IGM Resins, product name: Omnirad184) and 0.5 parts by weight of a leveling agent (manufactured by DIC Corporation, product name: F-568) were added. Furthermore, methyl ethyl ketone and toluene were added as solvents, and the mixture was stirred to dissolve, thereby obtaining primer layer coating solutions with a solids content of 22% by weight for Examples 1 to 6, 11, and Comparative Examples 1, 2, and 7. The mass ratio of methyl ethyl ketone to toluene was 8:2. <Primer layer coating liquids of Examples 7 to 10, 12 to 13, and Comparative Examples 3 to 6, and 8 to 9> Primer layer coating liquids of Examples 7 to 10, 12 to 13, and Comparative Examples 3 to 6, and 8 to 9 were obtained in the same manner as in Example 1, etc., except that the blending amount of the copolymer obtained in "3" above; the type and blending amount of the polyfunctional (meth)acrylate compound; the blending amount of the photopolymerization initiator; and the solids concentration of the primer layer coating liquid were changed to the conditions in Tables 1 and 2.

[0120] 5. Preparation of Optical Laminate [Example 1] The primer layer coating solution of Example 1 was applied to an 80 μm-thick triacetyl cellulose film (Fujitac TG60, manufactured by Fujifilm Corporation) and dried at 70° C. for 1 minute. Next, ultraviolet light was irradiated using a high-pressure mercury lamp under a nitrogen atmosphere to form a primer layer with a thickness of 2.7 μm. The ultraviolet light had an integrated light intensity of 400 mJ / cm ２ Next, the following hard coat layer coating solution 1 was applied onto the primer layer and dried at 70°C for 1 minute. Next, ultraviolet light was irradiated using a high-pressure mercury lamp under a nitrogen atmosphere to form a hard coat layer with a thickness of 3.5 µm, thereby obtaining the optical laminate of Example 1. The ultraviolet light had an integrated light intensity of 400 mJ / cm ２ <Coating Solution 1 for Hard Coat Layer> 100 parts by mass of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., product name: PET-30) as a polyfunctional (meth)acrylate compound, 4 parts by mass of a photopolymerization initiator (manufactured by IGM Resins, product name: Omnirad184), and 0.5 parts by mass of a leveling agent (manufactured by DIC Corporation, product name: F-568) were mixed. Further, methyl isobutyl ketone was added as a solvent, and the mixture was stirred to dissolve, thereby obtaining a coating solution with a solid content of 30% by mass.

[0121] [Examples 2 to 9, 11 to 13], [Comparative Examples 1 to 6, 8 to 9] Optical laminates of Examples 2 to 9, 11 to 13 and Comparative Examples 1 to 6, 8 to 9 were obtained in the same manner as in Example 1, except that the composition of the coating liquid for primer layer; the thickness of the primer layer; the integrated amount of ultraviolet light during primer layer formation; and the thickness of the hard coat layer were changed to the conditions shown in Tables 1 and 2.

[0122] [Example 10] An optical laminate of Example 10 was obtained in the same manner as in Example 1, except that the composition of the primer layer coating solution, the thickness of the primer layer, and the thickness of the hard coat layer were changed to the compositions or thicknesses shown in Table 1, and furthermore, Hard Coat Layer Coating Solution 1 was changed to Hard Coat Layer Coating Solution 2 described below. <Hard Coat Layer Coating Solution 2> 100 parts by mass of dipentaerythritol hexaacrylate as a polyfunctional (meth)acrylate compound, 4 parts by mass of a photopolymerization initiator (manufactured by IGM Resins, product name: Omnirad184), and 0.5 parts by mass of a leveling agent (manufactured by DIC, product name: F-568) were mixed. Further, methyl isobutyl ketone was added as a solvent, and the mixture was stirred to dissolve, obtaining a coating solution with a solids content of 30% by mass.

[0123] Comparative Example 7 An optical layered body of Comparative Example 7 was obtained in the same manner as in Example 1, except that a hard coat layer was not formed on the primer layer.

[0124]

[0125] In Tables 1 and 2, "PETA" means pentaerythritol triacrylate, "oligomer" means urethane acrylate oligomer manufactured by Arakawa Chemical Industries, Ltd. (product name: Beamset 577, number of functional groups: 3 to 6), "DPHA" means dipentaerythritol hexaacrylate, and "HDDA" means 1,6-hexanediol diacrylate.

[0126] From the results in Tables 1 and 2, it can be confirmed that the optical laminates of the examples reduce blue light, have excellent scratch resistance and adhesion, and can suppress a decrease in brightness.

[0127] 10: Substrate 20: Primer layer 30: Hard coat layer 100: Optical laminate 110: Display element 120: Image display panel

Claims

1. An optical laminate having a hard coat layer on a substrate, comprising a primer layer containing a benzotriazole-based compound between the substrate and the hard coat layer, and satisfying the following conditions 1 to 3. Condition 1: The optical laminate has a spectral transmittance of less than 1.00% at a wavelength of 410 nm, a spectral transmittance of 15.00% or more and less than 85.00% at a wavelength of 450 nm, and a spectral transmittance of 85.00% or more at a wavelength of 490 nm. Condition 2: The average indentation hardness of the cross section of the primer layer at a position 1.0 μm in the thickness direction from the interface between the hard coat layer and the primer layer is 190 MPa or more. Condition 3: When the adhesion between the primer layer and the hard coat layer in the optical laminate is evaluated by the cross-cut method of JIS K5600-5-6:1999, the evaluation is classified as 0 or 1.

2. The optical laminate according to claim 1, wherein the spectral transmittance of the optical laminate increases gradually from a wavelength of 410 nm to a wavelength of 490 nm.

3. The optical laminate according to claim 1, wherein, when the spectral transmittance of the optical laminate at a wavelength of 455 nm is defined as X%, and the spectral transmittance of the optical laminate at a wavelength of 445 nm is defined as Y%, X-Y is 15.00% or more.

4. The optical laminate according to claim 1, wherein the average indentation hardness of a cross section of the hard coat layer at a position 1.0 μm away from the interface between the hard coat layer and the primer layer in the thickness direction is 300 MPa or more.

5. The optical laminate according to claim 1, wherein the substrate is a triacetyl cellulose film or an acrylic film.

6. The optical laminate according to claim 1, wherein under condition 2, the average indentation hardness of the cross section of the primer layer is 190 MPa or more and 400 MPa or less.

7. The optical laminate according to claim 1, wherein the thickness of the primer layer is 1.3 μm or more and 7.5 μm or less.

8. A polarizing plate having a polarizer, a first transparent protective plate arranged on one side of the polarizer, and a second transparent protective plate arranged on the other side of the polarizer, wherein one of the first transparent protective plate and the second transparent protective plate is an optical laminate described in any one of claims 1 to 7, and the surface of the optical laminate facing the hard coat layer is arranged to face the opposite side to the polarizer.

9. An image display panel having a display element and an optical film arranged on the light emission surface side of the display element, the optical film comprising an optical laminate according to any one of claims 1 to 7, and arranged so that the surface of the optical laminate on the hard coat layer side faces away from the display element.

10. An image display device comprising the image display panel according to claim 9.

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