Front panel, optical laminate, and image display device

Abstract

The present application provides a front panel, the front panel (4) is 10nm or less in the in-plane direction phase difference Re(550) measured with light of wavelength 550nm.

Description

Technical Field

[0001] This invention relates to front panels, optical laminates, and image display devices. Background Technology

[0002] As a front panel, an optical film having, for example, a glass substrate and a resin layer formed of silicone resin has been proposed (see, for example, Patent Document 1 below).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: WO2019 / 066078 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In recent years, there has been a demand for higher quality front panels.

[0008] This invention provides a high-quality front panel, optical laminate, and image display device.

[0009] Problem Solving Methods

[0010] The present invention (1) includes a front panel having an in-plane phase difference Re(550) of less than 10 nm as measured by light with a wavelength of 550 nm.

[0011] The in-plane phase difference Re(550) of the front panel is low, below 10nm. Therefore, the front panel will not have visual recognition problems caused by phase difference, which is of high quality.

[0012] The present invention (2) includes the front panel described in (1), which has a protective resin layer and a hard coating layer in sequence in the thickness direction.

[0013] The front panel has excellent scratch resistance because it has a protective resin layer and a hard coating layer in sequence in the thickness direction.

[0014] The present invention (3) includes the front panel described in (2), wherein, with the above-mentioned hard coating as the inner side, the front panel is fixed in a state of bending 180 degrees with a diameter of 4 mm and placed in an environment of 85°C and 85%RH for 100 hours, and then the front panel is released, and the difference Δ between the in-plane direction phase difference Re(550) of the bent portion and the in-plane direction phase difference Re(550) of the bent portion before the bending test is less than 10 nm.

[0015] However, depending on the application and purpose, the front panel may sometimes be bent. In such cases, when the front panel bends around the bend, stress concentration occurs at the bend, and therefore, the in-plane phase difference Re(550) is prone to change.

[0016] In this front panel, since the difference in the in-plane phase difference Re(550) of the bent portion before and after the bending test is less than 10 nm, the change in the in-plane phase difference Re(550) can be suppressed even if stress concentration occurs in the bent portion, thereby maintaining high quality.

[0017] The present invention (4) includes the front panel described in (2) or (3), which further comprises a substrate and an adhesive layer, wherein the substrate, the adhesive layer, the protective resin layer and the hard coating are arranged sequentially in the thickness direction, and the substrate comprises a thin glass plate.

[0018] Because the front panel further includes a substrate and an adhesive layer, with the substrate, adhesive layer, protective resin layer, and hard coating layer arranged sequentially in the thickness direction, and the substrate comprising a thin glass plate, the generation of residual marks after bending (such as wrinkles) can be suppressed, thereby maintaining high quality. The thin glass plate is isotropic, therefore, the phase difference is very small, and the front panel can maintain rigidity while remaining transparent.

[0019] The present invention (5) includes the front panel of any one of (2) to (4), wherein the thickness of the protective resin layer is 30 μm or more.

[0020] However, thin glass sheets are fragile, which can easily reduce the impact resistance of the substrate.

[0021] In this front panel, the thickness of the protective resin layer can be increased without causing visual recognition problems caused by phase difference. Since the protective resin layer is thicker, exceeding 30μm, it can suppress the reduction of impact resistance.

[0022] The present invention (6) includes the front panel described in any one of (1) to (5), wherein the absolute value of the photoelastic coefficient at 23°C is 100.0 × 10⁻⁶. -13 cm 2 / dyn or less.

[0023] The absolute value of the photoelastic coefficient of the front panel at 23°C is 100.0 × 10⁻⁶. -13 cm 2 It has a low / dyn value, resulting in excellent flexibility.

[0024] The present invention (6) includes an optical laminate having a polarizing film and a front panel as described in any one of (1) to (5) in sequence toward the visible side.

[0025] This optical laminate is of high quality because it has the aforementioned front panel.

[0026] The present invention (7) includes an image display device having an image display component and the optical laminate described in (6) in sequence on the visible side.

[0027] This image display device is of high quality because it has the aforementioned optical laminate.

[0028] The effects of the invention

[0029] The front panel, optical laminate, and image display device of the present invention do not suffer from visual recognition problems caused by phase difference, and are of high quality. Attached Figure Description

[0030] Figure 1 This is a cross-sectional view of an organic EL display device according to one embodiment of the image display device of the present invention.

[0031] Figure 2 This is a cross-sectional view of one embodiment of the optical laminate of the present invention.

[0032] Figure 3 This is a cross-sectional view of one embodiment of the front panel of the present invention.

[0033] Figure 4 This is a cross-sectional view illustrating the bending state of the front panel during a bending test.

[0034] Symbol Explanation

[0035] 1 Organic EL display device

[0036] 2 Optical laminates

[0037] 3 Image display components

[0038] 4. Front panel

[0039] 6 Protective components

[0040] 7 substrate

[0041] 9 First adhesive layer

[0042] 12 Protective resin layer

[0043] 13 Hard coating

[0044] 25. Bend

[0045] Re(550) is the in-plane phase difference measured with light at a wavelength of 550 nm.

[0046] Δ is the difference in phase in the in-plane direction before and after the bending test. Detailed Implementation

[0047] [Organic EL Display Device]

[0048] Reference Figure 1 An organic electroluminescent display device, which is one embodiment of the image display device of the present invention, will be described. Hereinafter, the organic electroluminescent display device will be simply referred to as an organic EL display device.

[0049] The organic EL display device 1, for example, has a flat panel shape, and is preferably configured to be bendable about a bend 25 located between two opposing edges 27 spaced apart in the surface direction (orthogonal to the front and back directions), and more preferably foldable. All components described below are preferably bendable, and more preferably foldable.

[0050] like Figure 1 As shown, the organic EL display device 1 includes an image display member 3 and an optical laminate 2 sequentially facing the viewable side. That is, in this organic EL display device 1, the optical laminate 2 and the image display member 3 are arranged sequentially opposite to the viewable side, which is the side for user visual recognition. It should be noted that in the organic EL display device 1, the viewable side corresponds to the surface side, and the opposite side corresponds to the back side.

[0051] [Optical laminate]

[0052] The optical laminate 2 has a front panel 4 and a polarizing film 5 sequentially on the back side.

[0053] [Front Panel]

[0054] The front panel 4 is sometimes referred to as a cover window or window film. The front panel 4 has a protective member 6 and a base plate 7 arranged sequentially on the rear side.

[0055] [Adhesive layer and its composition]

[0056] Furthermore, the organic EL display device 1 includes an adhesive layer 8 located between adjacent components in the front-to-back direction. The adhesive layer 8, facing the back side, sequentially includes, as an example, a first adhesive layer 9, a second adhesive layer 10, and a third adhesive layer 11. Therefore, in the organic EL display device 1, the protective component 6, the first adhesive layer 9, the substrate 7, the second adhesive layer 10, the polarizing film 5, the third adhesive layer 11, and the image display component 3 are arranged sequentially facing the back side.

[0057] [Protective Components]

[0058] The protective member 6 protects the substrate 7 from the surface side. The protective member 6 has a flat plate shape extending along the surface direction. The protective member 6 includes a protective resin layer 12 and a hard coating layer 13 in sequence facing the surface side.

[0059] [Protective resin layer]

[0060] A protective resin layer 12 forms the back side of the protective member 6. The protective resin layer 12 extends along the surface direction. The material of the protective resin layer 12 is not particularly limited as long as it is a resin that can satisfy the in-plane phase difference Re(550) described later. Specifically, examples of materials for the protective resin layer 12 include acrylic resin, polycarbonate resin, etc. From the viewpoint of reducing the in-plane phase difference Re(550), acrylic resin and polycarbonate resin are preferred as materials for the protective resin layer 12, and from the viewpoint of suppressing the change of the in-plane phase difference Re(550) of the bent portion 25 before and after bending, acrylic resin is more preferred.

[0061] Acrylic resins, for example, have glutarimide units and unsaturated carboxylic acid alkyl ester units. Specifically, acrylic resins have structural units of glutarimide units represented by formula (1) and unsaturated carboxylic acid alkyl ester units represented by formula (2).

[0062] [Chemical Formula 1]

[0063]

[0064] (In equation (1), R) 1 and R 2 Each can be independently represented by either a hydrogen atom or an alkyl group having 1 or more but less than 8 carbon atoms. R 3 It refers to an alkyl group having 1 or more but less than 18 carbon atoms, a cycloalkyl group having 3 or more but less than 12 carbon atoms, or an aryl group having 6 or more but less than 10 carbon atoms.

[0065] [Chemical Formula 2]

[0066]

[0067] (In equation (2), R) 4 and R 5 This refers to an alkyl group having 1 or more hydrogen atoms and 6 or fewer carbon atoms.

[0068] In equation (1), R is used as 1 and R 2 Alkyl groups with 1 or more but less than 8 carbon atoms are represented, for example: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, etc.

[0069] As R 1 Methyl groups can be preferred.

[0070] As R 2 Hydrogen atoms can be selected as an example.

[0071] As R 3 Alkyl groups representing 1 to 18 carbon atoms, in addition to those exemplified in alkyl groups with 1 to 8 carbon atoms, may include: nonyl, decyl, dodecyl, undecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecanyl, octadecyl, etc. Cycloalkyl groups representing 3 to 12 carbon atoms may include: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, etc. Aryl groups representing 6 to 10 carbon atoms may include: phenyl, naphthyl, etc. As R 3 Alkyl groups are preferred, and methyl groups are more preferred.

[0072] In equation (2), R is used as 4 and R 5 Alkyl groups having 1 or more but less than 6 carbon atoms can be represented by, for example, methyl, ethyl, propyl, butyl, pentyl, etc., with methyl being a preferred example.

[0073] As R 4 Hydrogen atoms can be selected as an example.

[0074] As R 5 Methyl, can be preferred as an example

[0075] The content of glutarimide units in the acrylic resin is, for example, 5 mol% or more, preferably 15 mol% or more, and also, for example, 50 mol% or less, preferably 40 mol% or less. When the content of glutarimide units is above the lower limit and below the upper limit mentioned above, the phase difference can be reduced.

[0076] Furthermore, the imidization rate of the acrylic resin is the proportion of imide carbonyl groups in all carbonyl groups, for example, 2.5% or more, and preferably 7.5% or less, and more preferably 5.0% or less. When the imidization rate of the acrylic resin is above the lower limit mentioned above, the decrease in heat resistance and the decrease in transparency can be suppressed. When the imidization rate of the acrylic resin is below the upper limit mentioned above, the moldability and transparency are excellent. It should be noted that the imidization rate in the acrylic resin can be determined by NMR spectroscopy, IR spectroscopy, etc.

[0077] The proportion of unsaturated carboxylic acid alkyl ester units in the acrylic resin is the balance of the proportion of glutarimide units, for example, 50 mol% or more, preferably 60 mol% or more, and also, for example, 95 mol% or less, preferably 85 mol% or less. The acrylate units in the acrylic resin (specifically, the acrylate units in the total amount of glutarimide units, methacrylic acid units, and acrylate units) are, for example, less than 1% by mass, preferably less than 0.5% by mass. When the acrylate units are below the above upper limit, the acrylic resin exhibits excellent thermal stability, and the degradation of the acrylic resin's properties during resin manufacturing or molding processing can be suppressed. The acid value of the acrylic resin is, for example, 0.10 mmol / g or more, and for example, 0.50 mmol / g or less. When the acid value is within the above range, an acrylic resin with an excellent balance of heat resistance, mechanical properties, and molding processability can be obtained.

[0078] The acid value of acrylic resin is the content of carboxylic acid units and carboxylic anhydride units in the acrylic resin. The acid value can be calculated, for example, by the titration method described in WO2005-054311 or the titration method described in Japanese Patent Application Publication No. 2005-23272.

[0079] Acrylic resins may contain other copolymerizable vinyl monomer units besides those mentioned above. Examples of other vinyl monomers include styrene, α-methylstyrene, vinyltoluene, divinylbenzene, and other alkenyl aromatic monomers.

[0080] The weight-average molecular weight of the acrylic resin is, for example, 1000 or more, preferably 5000 or more, more preferably 10000 or more, and for example, 2000000 or less, preferably 1000000 or less, more preferably 500000 or less. The weight-average molecular weight of the acrylic resin is determined using a gel permeation chromatography (GPC system) and converted from polystyrene.

[0081] The thickness of the protective resin layer 12 is, for example, 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and also, for example, 100 μm or less, preferably 80 μm or less. When the thickness of the protective resin layer 12 is at or above the aforementioned lower limit, it is possible to suppress the reduction in impact resistance when the substrate 7 is a thin glass plate. When the thickness of the protective resin layer 12 is at or below the aforementioned upper limit, it is possible to improve foldability.

[0082] The total light transmittance of the protective resin layer 12 is, for example, 85% or more, preferably 88% or more, more preferably 90% or more, and, for example, 100% or less. The total light transmittance of the protective resin layer 12 can be determined according to JIS K 7361-1. The total light transmittance of other components can also be determined in the same way as described above.

[0083] The in-plane phase difference Re(550) of the protective resin layer 12 is, for example, less than 10 nm, preferably less than 5 nm, and especially preferably 0 nm, that is, it does not have an in-plane phase difference Re(550).

[0084] When the in-plane phase difference Re(550) of the protective resin layer 12 is below the above-mentioned upper limit, the in-plane phase difference Re(550) of the front panel 4 containing the protective resin layer 12 (described later) can reach the desired range.

[0085] It should be noted that "in-plane direction phase difference Re(550)" refers to the in-plane direction phase difference Re measured with light of wavelength 550nm. Even if the number 550 in parentheses changes, the definition of phase difference remains the same as above.

[0086] The thickness direction phase difference Rth(550) of the protective resin layer 12 is, for example, 30 nm or less, preferably 10 nm or less, and especially preferably 0 nm, that is, it does not have a thickness direction phase difference Rth(550).

[0087] When the phase difference Rth(550) in the thickness direction of the protective resin layer 12 is below the above-mentioned upper limit, the phase difference Rth(550) in the thickness direction of the front panel 4 containing the protective resin layer 12 (described later) can reach the desired range.

[0088] "Thickness direction phase difference Rth(550)" refers to the thickness direction phase difference Rth measured with light of wavelength 550nm. Even if the number 550 in parentheses of thickness direction phase difference Rth(550) changes, the definition of phase difference remains the same as above.

[0089] The in-plane phase difference Re(550) and the thickness phase difference Rth(550) can be measured using a phase difference measuring device. The following phase differences can also be measured using a phase difference measuring device.

[0090] Furthermore, the refractive index of the protective resin layer 12 can be appropriately adjusted so that the refractive index difference Δ between it and the hard coating layer 13 described later reaches a desired range. Specifically, when the protective resin layer 12 is isotropic, its refractive index n is, for example, 1.40 or more, preferably 1.48 or more, and also, for example, 1.60 or less, preferably 1.53 or less.

[0091] The absolute value of the photoelastic coefficient of the protective resin layer 12 at 23°C is, for example, 150.0 × 10⁻⁶. -13 cm 2 / dyn or less, preferably 100.0×10 -13 cm 2 / dyn or less, more preferably 50.0×10 -13 cm 2 / dyn or less, further preferably 30.0×10 -13 cm 2 / dyn or less, especially preferably 10.0×10 -13 cm 2 / dyn or less. Preferably, the in-plane phase difference Re(550) of the protective resin layer 12 is less than 5 nm, and the absolute value of the photoelastic coefficient at 23°C is 30.0 × 10⁻⁶. -13 cm 2 When the value is below / dyn, the difference Δ between the in-plane phase difference Re(550) of the bent portion 25 before and after the bending test can be significantly suppressed. Therefore, the bending performance is excellent, and thus the folding performance is excellent.

[0092] Furthermore, the in-plane phase difference Re(550) of the protective resin layer 12 is less than 5 nm, the thickness phase difference Rth(550) is less than 10 nm, and the absolute value of the photoelastic coefficient at 23°C is 30.0 × 10⁻⁶. -13 cm 2 When the value is below / dyn, the difference in in-plane phase difference Re(550) Δ and the difference in thickness phase difference Rth(550) Δ of the bent portion 25 before and after the bending test can be significantly suppressed. Therefore, the bending performance is better, and thus the folding performance is better.

[0093] The composition, properties, and manufacturing method of the protective resin layer 12 are detailed in, for example, Japanese Patent Application Publication No. 2016-151696.

[0094] [Hard coating]

[0095] The hard coating 13 is a protective component that suppresses damage to the surface of the organic EL display device 1 caused by friction. For example, when the optical laminate 2 is manufactured in a roll-to-roll manner, damage caused by pressure or friction during lamination is suppressed when the optical laminate 2 is laminated along the radial direction of the roller.

[0096] The hard coating 13 forms on the surface of the protective member 6. Furthermore, the hard coating 13 is disposed on one side of the protective resin layer 12 in the thickness direction. Specifically, the hard coating 13 contacts the surface (one side in the thickness direction) of the protective resin layer 12. The hard coating 13 extends along the surface direction.

[0097] The hard coating 13 is formed, for example, from a cured body of a curable composition or a molded body of a thermoplastic composition. That is, materials for the hard coating 13 can be, for example, a curable composition or a thermoplastic composition. As materials for the hard coating 13, curable compositions are preferred, active energy ray curable compositions are more preferred, and ultraviolet curable compositions are even more preferred.

[0098] Specifically, the hard coating 13 is preferably formed from a cured body (cured resin) of a curable composition, and more preferably from a cured body (cured acrylic resin) of a curable acrylic composition.

[0099] The curable composition contains a UV-curable compound. The curable compound can be any substance among monomers, oligomers, and prepolymers.

[0100] Specifically, examples of curable compounds include acrylic compounds (monomers and / or oligomers) having multiple UV-polymerizable functional groups, and preferably curable compounds having multiple (meth)acryloyl groups. The number of functional groups ((meth)acryloyl groups) in the curable compound is, for example, 3 or more, preferably 5 or more, and also, for example, 30 or less, preferably 20 or less.

[0101] Furthermore, the curable compound preferably contains hydroxyl groups within the molecule.

[0102] Examples of monomeric cured compounds include: tricyclodecanediethanol diacrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane triacrylate, pentaerythritol tetra(meth)acrylate, dimethylolpropane tetraacrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol (meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, dipropylene glycol diacrylate, isocyanurate tri(meth)acrylate, ethoxylated glycerol tri(meth)acrylate, ethoxylated pentaerythritol tetraacrylate, and their oligomers or prepolymers. These compounds can be used alone or in combination.

[0103] Examples of cured compounds in the form of monomers or oligomers include, for example, urethane (meth)acrylates and / or oligomers of urethane (meth)acrylates. The number of (meth)acryloyl groups in the urethane (meth)acrylate and / or oligomers of urethane (meth)acrylates is, for example, 3 or more, preferably 4 or more, more preferably 6 or more, and furthermore, for example, 25 or less, preferably 20 or less.

[0104] The weight-average molecular weight (or theoretical molecular weight) of urethane (meth)acrylate and / or urethane (meth)acrylate oligomers is, for example, 3000 or less, preferably 2500 or less, more preferably 2000 or less, and also, for example, 500 or more, preferably 800 or more. It should be noted that when the urethane (meth)acrylate and / or urethane (meth)acrylate oligomers are commercially available products, the theoretical molecular weight listed in the catalogue accompanying the commercially available product can be used.

[0105] To form the hard coating 13, if the hard coating 13 is a cured body, a varnish containing a curing composition is applied, and then the curing composition is cured. Alternatively, the hard coating 13 can be formed by directly molding a thermoplastic resin from a thermoplastic composition.

[0106] The tensile modulus E' of the hard coating 13 at 25°C is, for example, 3 GPa or less, preferably 2.5 GPa or less, and also, for example, 1.5 GPa or more, preferably 2 GPa or more. The tensile modulus E' of the hard coating 13 at 25°C can be obtained by measuring the dynamic viscoelasticity in a temperature dispersion mode at a frequency of 1 Hz and a heating rate of 5°C / min. When the tensile modulus E' of the hard coating 13 is below the above-mentioned upper limit, the bending (folding) property is excellent. When the tensile modulus E' of the hard coating 13 is above the above-mentioned lower limit, damage caused by slippage in the protective resin layer 12 can be effectively suppressed.

[0107] Furthermore, the pencil hardness of the hard coating 13 is, for example, 3H or higher, more preferably 4H or higher, and even more preferably 5H or higher. The pencil hardness can be measured according to JIS K 5400-5-4. When the pencil hardness of the hard coating 13 is above the aforementioned lower limit, damage caused by slippage in the protective resin layer 12 can be effectively suppressed.

[0108] The in-plane phase difference Re(550) of the hard coating 13 is, for example, 10 nm or less, preferably 5 nm or less. The thickness phase difference Rth(550) of the hard coating 13 is, for example, 30 nm or less, preferably 10 nm or less.

[0109] Furthermore, the refractive index of the hard coating 13 can be appropriately adjusted so that the difference Δ between its refractive index and that of the protective resin layer 12, which will be described below, reaches a desired range. Specifically, when the protective resin layer 12 is isotropic, its refractive index n is, for example, 1.40 or more, preferably 1.48 or more, and also, for example, 1.60 or less, preferably 1.53 or less.

[0110] The thickness of the hard coating 13 is, for example, 5 μm or more, preferably 7 μm or more, and also, for example, 30 μm or less.

[0111] The total light transmittance of the hard coating 13 is, for example, 85% or more, preferably 90% or more, more preferably 95% or more, and, for example, 100% or less.

[0112] The composition, physical properties, and manufacturing method of the hard coating 13 are detailed in, for example, Japanese Patent Application Publication No. 2016-151696.

[0113] [Physical properties of protective components]

[0114] The thickness of the protective member 6 is, for example, 15 μm or more, preferably 35 μm or more, and also, for example, 130 μm or less, preferably 90 μm or less.

[0115] The total light transmittance of the protective member 6 is, for example, 85% or more, preferably 90% or more, more preferably 95% or more, and, for example, 100% or less.

[0116] The in-plane phase difference Re(550) of the protective member 6 is, for example, 10 nm or less, preferably 5 nm or less. The thickness phase difference Rth(550) of the protective member 6 is, for example, 30 nm or less, preferably 10 nm or less.

[0117] With the hard coating 13 as the inner side, the protective member 6 is fixed in a state where it is bent at 180 degrees with a diameter of 4 mm and placed in an environment of 85°C and 85%RH for 100 hours. Then the protective member 6 is released. The difference Δ between the in-plane phase difference Re(550) of the bent portion 25 and the in-plane phase difference Re(550) of the bent portion 25 before the bending test is, for example, 10 nm or less. In addition, the difference Δ between the thickness direction phase difference Rth(550) of the bent portion 25 after the bending test and the thickness direction phase difference Rth(550) of the bent portion 25 before the bending test is, for example, 30 nm or less. It should be noted that the details of the bending test will be described in detail in the following section [Significant Features of One Embodiment].

[0118] [Substrate]

[0119] The substrate 7 forms the back side of the front panel 4. The substrate 7 is bonded to the protective resin layer 12 via the first adhesive layer 9, which will be described later. In addition, the substrate 7 is flexible, for example.

[0120] Examples of substrate 7 include resin films such as polyimide films and thin glass sheets. From the viewpoint of obtaining excellent flexibility, and consequently excellent foldability, hardness, and transparency, thin glass sheets are preferred as substrate 7. In this embodiment, substrate 7 is preferably made of thin glass sheets.

[0121] The substrate 7 ensures the mechanical strength and toughness of the front panel 4. The substrate 7 supports the protective member 6 from the rear side. The substrate 7 has a flat plate shape extending along the surface direction.

[0122] The thickness of the substrate 7 is, for example, 10 μm or more, and preferably 100 μm or less, or more preferably 80 μm or less.

[0123] The total light transmittance of the substrate 7 is, for example, 80% or more, preferably 85% or more, and also, for example, 95% or less.

[0124] The thin glass plate is preferably isotropic. The refractive index n of the thin glass plate is, for example, 1.45 or higher, and also, for example, 1.55 or lower. It should be noted that when the thin glass plate is isotropic, it does not have an in-plane phase difference Re(55°).

[0125] [Polarizing film]

[0126] The polarizing film 5 is disposed on the back side of the front panel 4. Thus, the polarizing film 5 is protected by the front panel 4. The polarizing film 5 is bonded to the substrate 7 via the second adhesive layer 10, described later. The polarizing film 5 has a flat plate shape extending along the surface direction.

[0127] The thickness of the polarizing film 5 is, for example, 15 μm or more, preferably 25 μm or more, and also, for example, 300 μm or less, preferably 250 μm or less. The total light transmittance of the polarizing film 5 is, for example, 85% or more, preferably 90% or more, and also, for example, 100% or less.

[0128] The polarizing film 5 has a polarizer protective film 17, a polarizer 18 and an optical compensation layer 1 sequentially on the back side.

[0129] [Polarizer Protective Film]

[0130] The polarizer protective film 17 forms the surface of the polarizing film 5. The polarizer protective film 17 extends along the surface direction. The polarizer protective film 17 protects the polarizer 18, which will be described next, from the surface side.

[0131] The material of the polarizer protective film 17 is not particularly limited, and examples include: polyethylene terephthalate resin, polyethylene naphthalate resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, polyaryl ester resin, polyphenylene sulfide resin, etc. These resins can be used alone or in combination. As a material for the polarizer protective film 17, from the viewpoint of making the optical laminate 2 of high quality, acrylic resin is an example, and more preferably, an acrylic resin having, for example, unsaturated carboxylic acid alkyl ester units and glutarimide units, specifically the acrylic resin exemplified in the protective resin layer 12.

[0132] The thickness of the polarizer protective film 17 is, for example, 10 μm or more, and more preferably 100 μm or less, and preferably 80 μm or less. The in-plane phase difference Re(550) and the thickness phase difference Rth(550) of the polarizer protective film 17 are, for example, 10 nm or less, and preferably 5 nm or less. When the polarizer protective film 17 is isotropic, its refractive index n is, for example, 1.40 or more, and preferably 1.48 or more, and more preferably 1.60 or less, and preferably 1.53 or less.

[0133] The composition, properties, and manufacturing method of the polarizer protective film 17 are detailed in, for example, Japanese Patent Application Publication No. 2016-151696.

[0134] [Polarizing filter]

[0135] The polarizer 18 contacts the back side of the polarizer protective film 17. The polarizer 18 has a flat plate shape extending along the surface direction. Examples of polarizers 18 include films obtained by dyeing and stretching hydrophilic films such as PVA films, films obtained by dehydrating PVA films, and films obtained by dehydrochlorinating polyvinyl chloride films. The polarizer 18 may be single-layered or multi-layered. The thickness of the polarizer 18 is, for example, 1 μm or more, preferably 3 μm or more, and also, for example, 15 μm or less, preferably 10 μm or less. The materials, composition, physical properties (birefringence, phase difference, refractive index, etc.), and manufacturing methods of the polarizer 18 are described in detail, for example, in Japanese Patent Application Publication No. 2016-151696.

[0136] [Optical compensation layer]

[0137] The optical compensation layer 19 is in contact with the back side of the polarizer 18. The optical compensation layer 19 has a flat plate shape extending along the surface direction. The optical compensation layer 19 is a phase retardation film, specifically, it functions as a λ / 4 waveplate. Thus, the polarizing film 5, which includes the polarizer 18 and the optical compensation layer 19, has excellent circular polarization. Materials with the following optical properties can be used as materials for the optical compensation layer 19, such as polycarbonate resin, polyvinyl acetal resin, cycloolefin resin, acrylic resin, cellulose ester resin, etc., preferably polycarbonate resin. The polycarbonate resin includes, for example, structural units from fluorene dihydroxy compounds, structural units from isosorbide dihydroxy compounds, and structural units from at least one dihydroxy compound selected from alicyclic diols, alicyclic diethanol, diethylene glycol, triethylene glycol or polyethylene glycol, and alkylene glycols or spirodiols.

[0138] The in-plane phase difference Re(550) of the optical compensation layer 19 is, for example, 100 nm or more, preferably 135 nm or more, and also, for example, 180 nm or less, preferably 155 nm or less. Furthermore, the in-plane phase difference Re(550) of the optical compensation layer 19 is greater than the in-plane phase difference Re(450) and less than the in-plane phase difference Re(650). Specifically, Re(450) / Re(550) is, for example, less than 1, preferably 0.95 or less, and also, for example, 0.8 or more. Re(550) / Re(650) is, for example, less than 1, preferably 0.97 or less, and also, for example, 0.8 or more.

[0139] The composition, properties, and manufacturing method of the optical compensation layer 19 are detailed in, for example, Japanese Patent Application Publication No. 2017-102443.

[0140] It should be noted that the polarizing film 5, which has a polarizer protective film 17, a polarizer 18 and an optical compensation layer 19, is described in detail in Japanese Patent Application Publication No. 2017-102443.

[0141] [Adhesive layer]

[0142] Adhesive layer 8 is an adhesive layer that bonds the above-mentioned components in the front-back direction (pressure-sensitive adhesive). As described above, adhesive layer 8 includes a first adhesive layer 9, a second adhesive layer 10, and a third adhesive layer 11.

[0143] The first adhesive layer 9, the second adhesive layer 10, and the third adhesive layer 11 extend along the surface direction. The thickness of each of the first adhesive layer 9, the second adhesive layer 10, and the third adhesive layer 11 is, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and also, for example, 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less.

[0144] The total light transmittance of each of the first adhesive layer 9, the second adhesive layer 10, and the third adhesive layer 11 is, for example, 85% or more, preferably 88% or more, more preferably 90% or more, and, for example, 100% or less.

[0145] Specifically, the in-plane phase difference Re(550) of the first adhesive layer 9 is, for example, less than 10 nm, and the thickness phase difference Rth(550) is, for example, less than 30 nm.

[0146] It should be noted that the composition, physical properties, and manufacturing method of the adhesive layer 8, which includes the first adhesive layer 9, are described in detail in, for example, Japanese Patent Application Publication No. 2018-28573.

[0147] [First Adhesive Layer]

[0148] The first adhesive layer 9 bonds the protective member 6 and the substrate 7 in the front-back direction. Specifically, the first adhesive layer 9 contacts (bonds) the back side of the protective resin layer 12 and the surface of the substrate 7.

[0149] [Second Adhesive Layer]

[0150] The second adhesive layer 10 bonds the front panel 4 and the polarizing film 5 in the surface-to-back direction. Specifically, the second adhesive layer 10 contacts (bonds) the back side of the substrate 7 and the surface of the polarizing lens protective film 17.

[0151] [Third adhesive layer]

[0152] The third adhesive layer 11 bonds the optical laminate 2 and the image display component 3 in the surface-back direction. Specifically, the third adhesive layer 11 is bonded to the back side of the optical compensation layer 19 and the surface of the optical laminate 2.

[0153] [Materials of the adhesive layer]

[0154] Materials used for the first adhesive layer 9, the second adhesive layer 10, and the third adhesive layer 11 may include, for example, acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluoropolymer adhesives, epoxy adhesives, polyether adhesives, etc.

[0155] In particular, from the viewpoint of reducing the in-plane phase difference Re(550) of the front panel 4, acrylic adhesives are preferred as the material for the first adhesive layer 9. In addition, when the material of the first adhesive layer 9 is an acrylic adhesive, the thickness direction phase difference Rth(550) of the front panel 4 can also be reduced.

[0156] Examples of acrylic adhesives include cross-linked adhesives obtained by cross-linking a copolymer of (meth)acrylate containing an alkyl moiety with 3 or more and 8 or fewer carbon atoms and a (meth)acrylate containing a hydroxyalkyl moiety with 3 or more and 8 or fewer carbon atoms using a cross-linking agent.

[0157] Examples of alkyl methacrylates having an alkyl moiety with 3 or more but less than 8 carbon atoms include: n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, isohexyl methacrylate, 2-ethylhexyl methacrylate, and n-octyl methacrylate. n-butyl methacrylate is a preferred alkyl methacrylate.

[0158] Examples of hydroxyalkyl (meth)acrylates containing a hydroxyalkyl moiety with 3 or more but less than 8 carbon atoms include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate. 4-hydroxybutyl (meth)acrylate is a preferred example of a hydroxyalkyl (meth)acrylate. The mass fraction of the hydroxyalkyl (meth)acrylate relative to 100 parts by mass of the alkyl (meth)acrylate is, for example, 0.5 parts by mass or more, and, for example, 5 parts by mass or less.

[0159] Examples of crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. These crosslinking agents can be used alone or in combination. It is preferable to use isocyanate crosslinking agents in combination with peroxide crosslinking agents. Examples of isocyanate crosslinking agents include bifunctional and trifunctional types, with trifunctional types being preferred; specifically, trimethylolpropane adducts of dimethyl phthalate diisocyanate are examples. Examples of peroxide crosslinking agents include acyl peroxides, with benzoyl peroxide being a preferred example. The proportion of the crosslinking agent relative to 100 parts by weight of the copolymer is, for example, 0.01 parts by weight or more, and, for example, 1 part by weight or less. Furthermore, when isocyanate crosslinking agents and peroxide crosslinking agents are used in combination, the mass fraction of isocyanate crosslinking agent is, for example, 0.05 parts by mass and less than 0.2 parts by mass, and the mass fraction of peroxide crosslinking agent is, for example, 0.2 parts by mass and less than 0.5 parts by mass, relative to 100 parts by mass of the copolymer.

[0160] [Image Display Section]

[0161] The image display component 3 forms the back side of the organic EL display device 1. The image display component 3 is disposed on the back side of the optical laminate 2 via the third adhesive layer 11. The image display component 3 has a generally flat shape extending along the surface direction, and can be specifically exemplified as an organic EL element. For example, although not shown, the image display component 3 includes a display substrate, two electrodes, an organic EL layer sandwiched between the two electrodes, and a sealing layer. The thickness of the image display component 3 is, for example, 1 μm or more, and for example, 100 μm or less. It should be noted that the structure, physical properties, and manufacturing method of the image display component 3 are described in detail, for example, in Japanese Patent Application Publication No. 2018-28573.

[0162] Touch panel type input display device

[0163] Reference Figure 1The OLED display device 1 can further include a conductive layer 15 and a shielding layer 16, as shown in the hypothetical lines. Thus, the OLED display device 1 functions as a touch panel type input display device.

[0164] [Conductive layer]

[0165] The conductive layer 15 is disposed on the optical laminate 2, specifically on the back side of the third adhesive layer 11. The conductive layer 15 is, for example, embedded in the middle portion (middle portion in the thickness direction) of the third adhesive layer 11 in the front-back direction.

[0166] Materials used as conductive layer 15 include, for example, metal oxides, conductive fibers, metals, etc.

[0167] Examples of metal oxides include indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium gallium oxide (IGO), indium tin oxide (ITO), and antimony tin oxide (ATO). The total light transmittance of the conductive layer 15 formed from the metal oxide is, for example, 85% or more, preferably 88% or more, more preferably 90% or more, and, for example, 100% or less.

[0168] Examples of conductive fibers include metal nanowires and carbon nanotubes.

[0169] Examples of metals include gold, platinum, silver, and copper. It should be noted that when the conductive layer 15 is made of metal, the conductive layer 15 is a metal mesh, such as a mesh shape as seen from above. The width of the lines constituting the mesh is, for example, 100 μm or less, preferably 30 μm or less, more preferably 10 μm or less, and also, for example, 1 μm or more.

[0170] Details of the conductive layer 15 are described in, for example, Japanese Patent Application Publication Nos. 2017-102443, 2014-113705, and 2014-219667. It should be noted that the conductive layer 15 integrally comprises a sensor electrode portion 20 located at the center of the surface and lead-out wiring portions (not shown) located around the sensor electrode portion 20.

[0171] [Shielding layer]

[0172] A shielding layer 16 is disposed on the front panel 4, specifically, it is disposed on (specifically printed on) the peripheral portion of the back side of the protective resin layer 12. The shielding layer 16, when viewed from above, has a pattern including the lead-out wiring portion (or lead-out wiring) of the conductive layer 15. Examples of materials for the shielding layer 16 include compositions containing a black component and resin. The total light transmittance of the shielding layer 16 is, for example, 10% or less, preferably 5% or less. The shielding layer 16 is a layer in the organic EL display device 1 that prevents the user from visually recognizing the lead-out wiring portion (not shown) from the viewing side. When the optical laminate 2 is projected in the thickness direction, it includes a non-display area 21 that overlaps with the shielding layer 16, and a display area 22 that does not overlap with the shielding layer 16 but overlaps with the sensor electrode portion 20 of the conductive layer 15. When a shielding layer 16 is provided on the front panel 4, the in-plane phase difference Re (550) and the thickness phase difference Rth (550) of the front panel 4 are measured in the display area 22 of the front panel 4.

[0173] [A notable feature of one implementation]

[0174] Next, a significant aspect of the features of this embodiment will be described.

[0175] The in-plane phase difference Re(550) of the front panel 4 is less than 10nm.

[0176] When the in-plane phase difference Re(550) of the front panel 4 exceeds 10nm, it is impossible to manufacture a high-quality front panel 4.

[0177] The in-plane phase difference Re(550) of the front panel 4 is preferably less than 5 nm, more preferably less than 1 nm.

[0178] Furthermore, the phase difference Rth(550) in the thickness direction of the front panel 4 is, for example, 30 nm or less, preferably 15 nm or less, and more preferably 10 nm or less. When the phase difference Rth(550) in the thickness direction of the front panel 4 is above or below the aforementioned lower limit, it can be a high-quality front panel 4.

[0179] Furthermore, with the hard coating 13 as the inner side, the front panel 4 is fixed with a diameter of 4 mm and bent at 180 degrees. It is then placed in an environment of 85°C and 85% RH for 100 hours. After the front panel 4 is released, the difference Δ between the in-plane phase difference Re(550) of the bent portion 25 and the in-plane phase difference Re(550) of the bent portion 25 before the bending test is, for example, 10 nm or less, preferably 5 nm or less, more preferably 3 nm or less, further preferably 2 nm or less, and especially preferably 1 nm or less. In addition, the difference Δ between the thickness direction phase difference Rth(550) of the bent portion 25 after the bending test and the thickness direction phase difference Rth(550) of the bent portion 25 before the bending test is, for example, 30 nm or less, preferably 25 nm or less, more preferably 20 nm or less, further preferably 15 nm or less, and especially preferably 10 nm or less.

[0180] In bending tests, such as Figure 4 As shown, to make the hard coating of the front panel 4 (in) Figure 4 (Not shown in the image) The front panel 4 is supported from the back side by two glass plates 35, which are made to be the inner side, while the front panel 4 is bent. At this time, when the distance L between the surfaces of the front panel 4 opposite each other in the thickness direction is 4 mm, that is, when the bent part 25 is a semi-circular arc shape, its diameter (inner diameter) is 4 mm.

[0181] The absolute value of the photoelastic coefficient of the front panel 4 at 23°C is, for example, 150.0 × 10⁻⁶. -13 cm 2 / dyn or less, preferably 100.0×10 -13 cm 2 / dyn or less, more preferably 50.0×10 -13 cm 2 / dyn or less, further preferably 30.0×10 - 13 cm 2 / dyn or less, especially preferably 10.0×10 -13 cm 2 When the absolute value of the photoelastic coefficient of the front panel 4 is below the aforementioned upper limit, the difference Δ between Re(550) before and after the bending test can be set to below the aforementioned upper limit. Therefore, the front panel 4 exhibits excellent bending properties, and consequently, excellent folding properties.

[0182] Preferably, the in-plane phase difference Re(550) of the front panel 4 is less than 5 nm, and the absolute value of the photoelastic coefficient at 23°C is 30.0 × 10⁻⁶. -13 cm 2When the value is below / dyn, the difference Δ between the in-plane phase difference Re(550) of the bent portion 25 before and after the bending test can be significantly suppressed. Therefore, the bending performance is excellent, and thus the folding performance is excellent.

[0183] Furthermore, preferably, the phase difference Rth(550) in the thickness direction of the front panel 4 is less than 10 nm, and the absolute value of the photoelastic coefficient at 23°C is 30.0 × 10⁻⁶. -13 cm 2 When the bending density is below / dyn, the difference in in-plane phase difference Re(550) Δ and the difference in thickness phase difference Rth(550) Δ of the bending portion 25 before and after the bending test can be significantly suppressed. Therefore, the bending performance is excellent, and thus the folding performance is excellent.

[0184] [Other features of one implementation]

[0185] The difference Δ between the refractive index n of the protective resin layer 12 and the refractive index n of the hard coating layer 13 is, for example, 0.04 or less, preferably 0.03 or less, more preferably 0.02 or less, and even more preferably 0.01 or less.

[0186] <1> In detail, when both the protective resin layer 12 and the hard coating layer 13 are isotropic, the difference Δ between the refractive index n of the protective resin layer 12 and the refractive index n of the hard coating layer 13 is 0.04 or less, preferably 0.03 or less, more preferably 0.02 or less, and even more preferably 0.01 or less.

[0187] <2> When both the protective resin layer 12 and the hard coating layer 13 are birefringent, the difference Δ between their refractive indices nx in the slow axis direction is 0.04 or less, preferably 0.03 or less, more preferably 0.02 or less, and even more preferably 0.01 or less, and the difference Δ between their refractive indices in the fast axis direction is 0.04 or less, preferably 0.03 or less, more preferably 0.02 or less, and even more preferably 0.01 or less.

[0188] <3> When one of the protective resin layer 12 and the hard coating layer 13 is isotropic and the other is birefringent, the difference Δ between the refractive index n of one of them and the refractive index nx in the slow axis direction of the other is 0.04 or less, preferably 0.03 or less, more preferably 0.02 or less, and even more preferably 0.01 or less.

[0189] When the refractive index difference Δ exceeds the upper limit, it is sometimes impossible to obtain a high-quality front panel 4, a high-quality optical laminate 2, and a high-quality organic EL display device 1.

[0190] [Effects of one implementation method]

[0191] In the front panel 4 of the organic EL display device 1, the in-plane phase difference Re(550) is less than 10nm. Therefore, the front panel 4 will not have visual recognition problems caused by phase difference, and is a high-quality (high-precision) front panel.

[0192] Furthermore, the protective member 6 has a protective resin layer 12 and a hard coating layer 13 sequentially in the thickness direction. As a result, damage to the protective resin layer 12 caused by slippage can be effectively suppressed.

[0193] Furthermore, since the difference in in-plane phase Re(550) of the curved portion of the front panel 4 before and after the bending test is less than 10 nm, it is possible to suppress the occurrence of residual marks (wrinkles, etc.) after bending (bending, and then folding) of the curved portion 25, and to maintain the high quality of the curved portion 25. In other words, it has excellent bending resistance (folding resistance).

[0194] In addition, since the front panel 4 is provided with a substrate 7 containing a thin glass plate, a first adhesive layer 9, a protective resin layer 12 and a hard coating layer 13 arranged sequentially in the thickness direction, it has excellent bending resistance (folding resistance) and hardness.

[0195] However, since thin glass sheets are fragile, if substrate 7 contains thin glass sheets, the impact resistance of substrate 7 is easily reduced.

[0196] However, in this front panel 4, when the thickness of the protective resin layer 12 is thicker, exceeding 30 μm, the reduction in impact resistance can be suppressed. In this front panel 4, the in-plane phase difference Re(550) of the protective resin layer 12 is small, therefore, the thickness of the protective resin layer 12 can be increased without causing visual recognition problems caused by the phase difference.

[0197] In addition, the absolute value of the photoelastic coefficient of the front panel 4 at 23°C is 100.0 × 10⁻⁶. -13 cm 2 When the bending performance is below / dyn, the bending performance is excellent, which in turn leads to excellent folding performance.

[0198] The optical laminate 2 and the organic EL display device 1 have a high-quality front panel 4, thus resulting in high quality.

[0199] [Variation Example]

[0200] In the following variations, the reference numerals for the same components and processes as those in the above embodiment are omitted from detailed description. Furthermore, except where specifically described, each variation can achieve the same effect as the first embodiment. Moreover, an embodiment and its variations can be appropriately combined.

[0201] Although not shown in the figure, the back side of the conductive layer 15 can be in direct contact with the surface of the image display component 3.

[0202] In one embodiment, an organic EL display device 1 is exemplified as an example of the image display device of the present invention, but it is not limited thereto; for example, a liquid crystal display device (LCD) can also be cited.

[0203] The protective member 6 may further include a second hard coating layer 14. The second hard coating layer 14 is disposed on the surface of the hard coating layer 13. That is, the protective member 6 sequentially includes a protective resin layer 12, a hard coating layer 13, and a second hard coating layer 14 towards the surface. The second hard coating layer 14 is the same as the hard coating layer 13 in terms of physical properties and thickness, except for the following aspects. The tensile modulus E' of the second hard coating layer 14 at 25°C is, for example, lower than the tensile modulus E' of the second hard coating layer 13. The tensile modulus E' of the second hard coating layer 14 at 25°C is, for example, less than 2 GPa, preferably less than 1.5 GPa, and is, for example, more than 0.5 GPa, preferably more than 1 GPa. The tensile modulus E' of the second hard coating layer 14 at 25°C can be obtained by measuring the dynamic viscoelasticity in a temperature dispersion mode at a frequency of 1 Hz and a heating rate of 5°C / min.

[0204] like Figure 2 As shown, in this modified example, the optical laminate 2 may not be provided on the image display component 3, thus not constituting the organic EL display device 1. Specifically, the optical laminate 2 is a component used to manufacture the organic EL display device 1, and is not yet bonded to the optical laminate 2. In this case, a release liner 26, shown as an imaginary line, is laminated on the back side of the third adhesive layer 11. The optical laminate 2 is distributed as a separate component and is an industrially usable device.

[0205] Furthermore, although not illustrated, the front panel 4 may not be provided on the polarizing film 5 and thus does not constitute the optical laminate 2. In detail, the front panel 4 is a component used to fabricate the optical laminate 2 and is not yet bonded to the polarizing film 5. It should be noted that a second adhesive layer 10 may also be provided on the front panel 4. The front panel 4 is distributed as a separate component and is a device that can be used industrially.

[0206] like Figure 3 As shown, in the modified example, the front panel 4 may not include the substrate 7 and may only have the protective member 6. Specifically, Figure 3The modified example shows that the front panel 4 does not have the first adhesive layer 9 and the substrate 7, but is only composed of the protective member 6. In this modified example, the in-plane phase difference Re (550), the thickness phase difference Rth (550), the in-plane phase difference Re (550) of the bent portion 25 before and after the bending test, the thickness phase difference Rth (550) of the bent portion 25 before and after the bending test, and the absolute value of the photoelastic coefficient of the front panel 4 are the same as or approximately the same as those of the protective member 6.

[0207] Preferably, the front panel 4 further includes a first adhesive layer 9 and a substrate 7, wherein the substrate 7 comprises a thin glass plate. According to this configuration, the occurrence of residual marks (wrinkles, etc.) after bending (and folding) can be suppressed, thereby maintaining high quality.

[0208] Although not shown, the front panel 4 may not include the hard coating 13 and the substrate 7, but only have the protective resin layer 12. That is to say, the protective member 6 only has the protective resin layer 12.

[0209] The preferred protective member 6 has a protective resin layer 12 and a hard coating layer 13 sequentially in the thickness direction. This effectively suppresses damage to the protective resin layer 12 caused by slippage.

[0210] Example

[0211] The following examples and comparative examples illustrate the present invention in more detail. It should be noted that the present invention is not limited to the examples and comparative examples. Furthermore, the specific numerical values ​​of proportions (including proportions), physical property values, parameters, etc., used in the following description can be replaced with the corresponding upper limits (values ​​defined in the form of "less than" or "less than") or lower limits (values ​​defined in the form of "above" or "more than") of the proportions (including proportions), physical property values, parameters, etc., described in the above-described "Specific Embodiments".

[0212] [Example 1]

[0213] A coating agent was prepared by mixing 100 parts by weight of a multifunctional acrylate (manufactured by Aica Kogyo Co., Ltd., product name "Z-850-16"), 5 parts by weight of a leveling agent (manufactured by DIC Co., Ltd., trade name: GRANDIC PC-4100), and 3 parts by weight of a photopolymerization initiator (manufactured by Ciba Japan Co., Ltd., trade name: IRGACURE 907), and diluting the mixture with methyl isobutyl ketone to achieve a solids concentration of 50% by weight.

[0214] A protective resin layer 12 made of acrylic film (product name "HX-40N", thickness 40μm) manufactured by Nitto Denko Corporation was also prepared separately.

[0215] A coating agent is applied to one side of the prepared protective resin layer 12 to form a coating layer. The coating layer and the protective resin layer are then heated together at 90°C for 2 minutes. Next, a high-pressure mercury lamp is used to accumulate a light intensity of 300 mJ / cm². 2 The coating layer is irradiated with ultraviolet light, thereby forming a hard coating 13. The thickness of the hard coating 13 is 10 μm. Thus, as... Figure 3 As shown, a protective member 6 having a protective resin layer 12 and a hard coating layer 13 was fabricated. That is, a front panel 4 including the protective member 6 was fabricated.

[0216] [Example 2]

[0217] It was prepared using the same method as in Example 1. Figure 3 The front panel 4 is shown. In this panel, the protective resin layer 12 is replaced with a polycarbonate film made by the following method.

[0218] 81.98 parts by weight of isosorbide, 47.19 parts by weight of tricyclodecanediethanol, 175.1 parts by weight of diphenyl carbonate, and 0.979 parts by weight of a 0.2% by weight aqueous solution of cesium carbonate as a catalyst were added to a reaction vessel. In the first stage of the reaction, under a nitrogen atmosphere, the temperature of the heating tank was raised to 150°C, and the reactants were dissolved by stirring as needed (approximately 15 minutes). Next, the pressure was increased from atmospheric pressure to 13.3 kPa, and the temperature of the heating tank was raised to 190°C over one hour, while the generated phenol was extracted from the reaction vessel. After maintaining the reaction vessel at 190°C for 15 minutes, in the second stage, the pressure inside the reaction vessel was increased to 6.67 kPa, and the temperature of the heating tank was raised to 230°C over 15 minutes, where the generated phenol was extracted from the reaction vessel. The stirring torque of the mixer gradually increases. Therefore, in order to raise the temperature to 250°C in 8 minutes and remove the generated phenol, the pressure inside the reaction vessel is brought down to below 0.200 kPa. After reaching the given stirring torque, the reaction is stopped, and the resulting reactants are extruded into water to obtain polycarbonate resin granules. After vacuum drying the obtained polycarbonate resin at 80°C for 5 hours, a protective resin layer 12 consisting of a 135 μm thick polycarbonate film is produced using a film-forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 300 mm, set temperature: 250°C), a chilled roll (set temperature: 120–130°C), and a winding machine. The refractive index of the polycarbonate film is 1.51.

[0219] [Comparative Example 1]

[0220] It was prepared using the same method as in Example 1. Figure 3The front panel 4 shown is modified by replacing the protective resin layer 12 with a polyethylene terephthalate film (product name: T912E50-N) manufactured by Mitsubishi Chemical Corporation.

[0221] [Comparative Example 2]

[0222] It was prepared using the same method as in Example 1. Figure 3 The front panel 4 is shown. The protective resin layer 12 is replaced with a transparent polyimide film (product name: A50) manufactured by KOLON.

[0223] [Example 3]

[0224] On the back side of the protective resin layer 12 of the protective member 6 manufactured in Example 1, a substrate 7 made of a glass film (product name: G-Leaf (registered trademark)) (thickness 50μm) manufactured by Nippon Electric Glass Co., Ltd., which is a thin glass plate, is bonded via a first adhesive layer 9 formed by an acrylic adhesive. Thus, a front panel 4 having a substrate 7, a first adhesive layer 9, a protective resin layer 12 and a hard coating layer 13 in sequence in the thickness direction is manufactured.

[0225] [Example 4]

[0226] On the back side of the protective resin layer 12 of the protective member 6 manufactured in Example 2, a substrate 7 made of a glass film (product name: G-Leaf (registered trademark)) (thickness 50μm) manufactured by Nippon Electric Glass Co., Ltd., which is a thin glass plate, is bonded via a first adhesive layer 9 formed by an acrylic adhesive. Thus, a front panel 4 having a substrate 7, a first adhesive layer 9, a protective resin layer 12 and a hard coating layer 13 in sequence in the thickness direction is produced.

[0227] [Comparative Example 3]

[0228] On the back side of the protective resin layer 12 of the protective member 6 manufactured in Comparative Example 1, a substrate 7 made of a glass film (product name: G-Leaf (registered trademark)) (thickness 50μm) manufactured by Nippon Electric Glass Co., Ltd., which is a thin glass plate, is bonded via a first adhesive layer 9 formed by an acrylic adhesive. Thus, a front panel 4 having a substrate 7, a first adhesive layer 9, a protective resin layer 12 and a hard coating layer 13 in sequence in the thickness direction is manufactured.

[0229] [Comparative Example 4]

[0230] On the back side of the protective resin layer 12 of the protective member 6 manufactured in Comparative Example 2, a substrate 7 made of a glass film (product name: G-Leaf (registered trademark)) (thickness 50μm) manufactured by Nippon Electric Glass Co., Ltd., which is a thin glass plate, is bonded via a first adhesive layer 9 formed by an acrylic adhesive. Thus, a front panel 4 having a substrate 7, a first adhesive layer 9, a protective resin layer 12 and a hard coating layer 13 in sequence in the thickness direction is manufactured.

[0231] [evaluate]

[0232] The following items were measured on the front panels 4 of Examples 1-4 and Comparative Examples 1-4. Additionally, the following items were measured on the hard coating 13 and the protective resin layer 12. The results are shown in Table 1.

[0233] [Determination of in-plane phase difference Re(550) and thickness-direction phase difference Rth(550)]

[0234] The in-plane phase difference Re(550) of the front panel 4 was measured using an Axoscan manufactured by Axometrics. The measurement wavelength was 550 nm, and the measurement temperature was 23 °C.

[0235] Cut a 50mm x 50mm section from the front panel 4 and use it as the measurement sample.

[0236] The in-plane phase difference Re(550) of the protective resin layer 12 was also measured in the same manner as described above.

[0237] The in-plane phase difference Re(550) of the hard coating 13 was determined by the following method. First, the in-plane phase difference Re(550) of the protective member 6 having the hard coating 13 and the protective resin layer 12 was measured. Separately, the in-plane phase difference Re(550) of the protective resin layer 12 was measured only.

[0238] The difference between them is obtained as the in-plane phase difference Re(550) of the hard coating 13.

[0239] [Determination of photoelasticity coefficient]

[0240] The photoelastic coefficients of the front panel 4, hard coating 13, and protective resin layer 12 were measured using an automated birefringence measuring device ABR-10A-10AT manufactured by UNIOPT. The measurement wavelength was 632 nm, the measurement load range was 0–2 N, the calculated load range was 0.5–2 N, the loading speed was 0.1 mm / min, and the measurement temperature was 23 °C.

[0241]

[0242] It should be noted that the above invention is provided in the form of exemplary embodiments of the present invention, but this is merely an example and not intended to be limiting. Those skilled in the art will understand that variations of the present invention are included in the appended claims.

[0243] Industrial applicability

[0244] The front panel can be configured on an optical laminate. The optical laminate can be configured on an image display device.

Claims

1. A front panel, wherein the in-plane phase difference Re(550), measured with light at a wavelength of 550 nm, is less than 10 nm. The front panel has a protective resin layer and a hard coating layer in sequence along its thickness direction. The thickness of the protective resin layer is more than 10 μm and less than 40 μm. With the hard coating as the inner side, the front panel is fixed with a diameter of 4 mm and bent at 180 degrees. It is then placed in an environment of 85°C and 85%RH for 100 hours. After that, the front panel is released. The difference Δ between the in-plane phase difference Re(550) of the bent portion and the in-plane phase difference Re(550) of the bent portion before the bending test is less than 10 nm.

2. The front panel according to claim 1, further comprising a substrate and an adhesive layer, The substrate, the adhesive layer, the protective resin layer, and the hard coating are arranged sequentially in the thickness direction. The substrate comprises a thin glass plate.

3. The front panel according to claim 1, wherein, The thickness of the protective resin layer is more than 30 μm and less than 40 μm.

4. The front panel according to claim 2, wherein, The thickness of the protective resin layer is more than 30 μm and less than 40 μm.

5. The front panel according to any one of claims 1 to 4, wherein the absolute value of its photoelastic coefficient at 23°C is 100.0 × 10⁻⁶. -13 cm 2 / dyn or less.

6. An optical laminate, comprising, in sequence, the following components facing the visible side: polarizing film, and The front panel according to any one of claims 1 to 5.

7. An image display device, comprising, in sequence, the following components facing the viewable side: Image display components, and The optical laminate as described in claim 6.

Images