Optical laminate, member for display device, and display device

Abstract

To provide an optical laminate including a resin base material and a hard coat layer, having high surface hardness while having good flex resistance.SOLUTION: An optical laminate 10 comprises a resin base material 1, and a hard coat layer 2 arranged on one surface of the resin base material 1. When the optical laminate 10 is subjected to tension test, strain generated when a crack is generated in the hard coat layer 2 is denoted by A(%), strain when the optical laminate 10 is ruptured is denoted by B(%), modulus of tensile elasticity in a section where strain of the optical laminate 10 is between 1% and 2% is denoted by C(GPa), and thickness of the optical laminate 10 is denoted by D(μm), X1 value calculated by the following formula (1) is 0.10 or more. X1=(B-A)×C / D(1)SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an optical laminate, a member for a display device, and a display device. [Background technology]

[0002] On the surface of the display device, a laminate having various properties such as hard coating properties, abrasion resistance, anti-reflection properties, anti-glare properties, anti-static properties, anti-fouling properties, etc. is arranged as a front plate. For example, Patent Documents 1 and 2 disclose hard coating films having a substrate and a hard coating layer for the purpose of improving the scratch resistance of the image display surface of an image display device.

[0003] BACKGROUND ART In recent years, flexible displays such as foldable displays, rollable displays, and bendable displays have been actively developed, and among these, development of foldable displays, i.e., display devices that can be bent, has been progressing.

[0004] A laminate to be disposed on the surface of a display device is required to have high surface hardness. Furthermore, a flexible display is required to be able to withstand repeated bending without causing display defects, and a laminate to be disposed on the surface of a flexible display is required to have sufficient flex resistance to prevent peeling or cracking when repeatedly bent. However, a laminate having a hard coat layer has high surface hardness, which may result in reduced flex resistance. Therefore, there is a demand for an optical laminate that has a sufficiently high surface hardness and good flex resistance as a laminate to be disposed on the surface of a display device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-238614 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-186210 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure has been made in consideration of the above-described circumstances, and has as its main object to provide an optical laminate having a resin substrate and a hard coat layer, which has high surface hardness and good flex resistance. [Means for solving the problem]

[0007] One embodiment of the present disclosure provides an optical laminate having a resin substrate and a hard coat layer disposed on one surface of the resin substrate, wherein when a tensile test is performed on the optical laminate, the X1 value calculated by the following formula (1) is 0.10 or more, where A (%) is the strain when a crack occurs in the hard coat layer, B (%) is the strain when the optical laminate breaks, C (GPa) is the tensile modulus of the optical laminate in a strain range of 1% to 2%, and D (μm) is the thickness of the optical laminate. X1 = (BA) × C / D (1)

[0008] Another embodiment of the present disclosure provides a member for a display device, including the above-described optical laminate.

[0009] Another embodiment of the present disclosure provides a display device including a display panel and the above-described member for a display device disposed on a viewer side of the display panel. [Effects of the Invention]

[0010] The present disclosure has an effect of providing an optical laminate that has a sufficiently high surface hardness and good flex resistance as a laminate to be placed on the surface of a display device. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of an optical laminate according to the present disclosure. [Figure 2]1 is a schematic cross-sectional view illustrating an example of an optical laminate according to the present disclosure. [Figure 3] FIG. 1 is a schematic diagram illustrating a method for preparing a sample for a tensile test. [Figure 4] FIG. 1 is a schematic diagram illustrating a tensile test. [Figure 5] FIG. 1 is a schematic diagram for explaining a dynamic bending test. [Figure 6] 1 is a schematic cross-sectional view illustrating a member for a display device according to the present disclosure. [Figure 7] 1 is a schematic cross-sectional view illustrating a display device according to the present disclosure. [Figure 8] 1 shows the results of a dynamic bending test and a pencil hardness test for Examples and Comparative Examples. [Figure 9] FIG. 2 is a schematic diagram for explaining elongation when the optical laminate according to the present disclosure is bent. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different forms and should not be construed as being limited to the description of the embodiments exemplified below. Furthermore, to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual form, but these are merely examples and do not limit the interpretation of the present disclosure. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0013] In this specification, when describing an aspect in which another component is placed on a certain component, the term "above" or "below" refers to both a case in which another component is placed directly above or below the component so as to be in contact with the component, and a case in which another component is placed above or below the component with another component interposed therebetween, unless otherwise specified. Also, in this specification, when describing an aspect in which another component is placed on the surface of a certain component, the term "on the surface side" or "on the surface" refers to both a case in which another component is placed directly above or below the component so as to be in contact with the component, and a case in which another component is placed above or below the component with another component interposed therebetween, unless otherwise specified.

[0014] The optical laminate, the member for a display device, and the display device according to the present disclosure will be described in detail below.

[0015] A. Optical laminate The optical laminate according to the present disclosure is an optical laminate having a resin substrate and a hard coat layer disposed on one surface of the resin substrate, and when a tensile test is performed on the optical laminate, the X1 value calculated by the following formula (1) is 0.10 or more, where A (%) denotes the strain when a crack occurs in the hard coat layer, B (%) denotes the strain when the optical laminate breaks, C (GPa) denotes the tensile modulus of the optical laminate in a strain range of 1% to 2%, and D (μm) denotes the thickness of the optical laminate. X1 = (BA) × C / D (1)

[0016] FIG. 1 is a schematic cross-sectional view showing an example of an optical laminate according to the present disclosure. As shown in FIG. 1, the optical laminate 10 includes a resin substrate 1 and a hard coat layer 2 disposed on one surface of the resin substrate 1. When a tensile test is performed on the optical laminate 10 including the resin substrate 1 and the hard coat layer 2, a crack first occurs in the hard coat layer 2, and then the crack that occurred in the hard coat layer 2 initiates the fracture of the entire optical laminate 10. The present disclosure is characterized in that, when the strain of the optical laminate 10 when a crack occurs in the hard coat layer 2 is A (%), the strain of the optical laminate 10 when the optical laminate 10 fractures is B (%), the tensile modulus of elasticity in the range of 1% to 2% strain of the optical laminate 10 is C (GPa), and the thickness of the optical laminate 10 is D (μm), the X1 value calculated by the above formula (1) is within a predetermined range.

[0017] In the above formula (1), (BA) represents the difference between the strain at which the optical laminate breaks and the strain at which cracks occur in the hard coat layer when a tensile test is performed. When the optical laminate of the present disclosure is stretched and a tensile test is performed, both the hard coat layer and the resin substrate are stretched, but the harder and thinner hard coat layer breaks first, causing cracks to occur in the hard coat layer. Subsequently, the resin substrate breaks from the crack in the hard coat layer, causing the entire optical laminate to break. A large (BA) indicates that when a tensile test is performed on an optical laminate having a resin substrate and a hard coat layer, even if a crack occurs in the hard coat layer, the entire optical laminate does not break immediately. On the other hand, a small (BA) means that if a crack occurs in the hard coat layer in a tensile test, the entire optical laminate is more likely to break.

[0018] Here, in order to improve the hardness of the hard coat layer, it is necessary to increase the crosslink density of the hard coat layer. Increasing the crosslink density of the hard coat layer tends to decrease A. When A decreases, B also decreases due to the pull of the rigidity of the hard coat layer, and the optical laminate cannot withstand elongation when bent, and bending resistance tends to decrease. In the present disclosure, even if A decreases, B does not decrease, that is, by increasing (BA), it is possible to achieve both surface hardness and bending resistance. Note that if the purpose is only to improve bending resistance, it is sufficient to make the hard coat layer low hardness, but in order to achieve both sufficiently high surface hardness and bending resistance for a laminate placed on the surface of a display device, it is necessary to increase (BA).

[0019] Furthermore, C indicates the tensile modulus (GPa) of the optical laminate in the strain range of 1% to 2% when a tensile test is performed. The larger C is, the higher the tensile modulus in the strain range of 1% to 2%, i.e., the modulus of elasticity when the optical laminate is stretched. When the optical laminate is bent, the surface located on the outside (outer surface) is stretched relative to the neutral plane of the optical laminate. If the modulus of elasticity in the stretched state is high, plastic deformation is less likely to occur, resulting in good bending resistance.

[0020] Figure 9 shows a schematic diagram illustrating the elongation of the neutral plane NS and outer surface S1 of the bent portion (10R in Figure 5) of an optical laminate with a thickness t of 50 μm (0.05 mm) when the optical laminate is bent with a bending radius r of 1.5 mm (the spacing d in Figure 5 is 3 mm). When the neutral plane NS is located at the center of the optical laminate in the thickness direction, the length of the neutral plane NS is (r + t / 2) × 2 × π × (1 / 2) = 4.79 mm, and the length of the outer surface S1 is (r + t) × 2 × π × (1 / 2) = 4.87 mm. In this case, the outer surface S1 elongates (4.87 - 4.79) mm relative to the neutral plane NS, and the strain at this time is (4.87 - 4.79) / 4.79 × 100 = 1.67%. In reality, the position of the neutral plane in the laminate varies depending on the elastic modulus and thickness of each layer (resin substrate and hard coat layer).

[0021] Therefore, in the present disclosure, the tensile modulus is the tensile modulus in the range of strain from 1% to 2%.

[0022] D indicates the thickness (μm) of the optical laminate. The thicker the optical laminate, the greater the tensile stress applied to the resin substrate on the outside of the optical laminate in a bending test at the same bending radius, resulting in a decrease in bending resistance. On the other hand, the thinner the optical laminate, the smaller the tensile stress applied to the resin substrate on the outside of the optical laminate in a bending test at the same bending radius, resulting in an improvement in bending resistance.

[0023] The inventors of the present application have derived the above formula (1) as an index showing the surface hardness and bending resistance based on the difference in strain from when a crack occurs in the hard coat layer to when the optical laminate breaks in a tensile test, a predetermined tensile modulus of the optical laminate, and the influence of the thickness of the optical laminate on the surface hardness and bending resistance, as well as experimental results such as those described in Examples and Comparative Examples below, and have found that both surface hardness and bending resistance can be achieved when the value X1 calculated by the above formula (1) is within a predetermined range.

[0024] 1. X1 value calculated by formula (1) In the optical laminate of the present disclosure, when a tensile test is performed on the optical laminate, the X1 value calculated by the following formula (1) is 0.10 or more, where A (%) is the strain when a crack occurs in the hard coat layer, B (%) is the strain when the optical laminate breaks, C (GPa) is the tensile modulus of the optical laminate in a strain range of 1% to 2%, and D (μm) is the thickness of the optical laminate. X1 = (BA) × C / D (1)

[0025] The X1 value calculated by the above formula (1) is 0.10 or more, preferably 0.13 or more, and more preferably 0.15 or more. 0.20 or more is particularly preferred. If the X1 value is too small, (BA) becomes relatively small, the tensile modulus of elasticity of the optical laminate becomes relatively small, or the thickness of the optical laminate becomes relatively large. This may result in a decrease in flex resistance and surface hardness. Therefore, in the present disclosure, by setting X1 within the above range, good flex resistance and surface hardness are achieved.

[0026] On the other hand, the X1 value calculated by the above formula (1) is, for example, 3.0 or less, or may be 2.0 or less, 1.5 or less, or may be 1.0 or less. If the X1 value is too large, the surface hardness may decrease.

[0027] The X1 value can be adjusted by adjusting the strain A when a crack occurs in the hard coat layer in a tensile test, the strain B when the optical laminate breaks in a tensile test, the tensile modulus C of the optical laminate in the strain range of 1% to 2%, and the thickness D of the optical laminate.

[0028] In the above formula (1), (BA) is, for example, 1.5% or more, preferably 2.0% or more, and more preferably 2.5% or more. By having (BA) in the above range, surface hardness and flex resistance can be improved. On the other hand, (BA) is, for example, 30.0% or less, preferably 25.0% or less, and more preferably 20.0% or less. (BA) is, for example, 1.5% or more and 30.0% or less, preferably 2.0% or more and 25.0% or less, and more preferably 2.5% or more and 20.0% or less.

[0029] Examples of means for adjusting (BA) include adjusting the thickness of the intermediate layer, which will be described later, and selecting the type of intermediate layer. For example, (BA) can be increased by disposing a primer layer as the intermediate layer. For example, (BA) can be increased by disposing a permeation layer of a predetermined thickness as the intermediate layer.

[0030] Other means for adjusting (BA) include a method for adjusting the material and thickness of the resin substrate, and a method for adjusting the material and thickness of the hard coat layer, thereby adjusting the strain A and the strain B, respectively.

[0031] The strain A when cracks occur in the hard coat layer in a tensile test is not particularly limited as long as it satisfies the above-mentioned X1 value range, but is, for example, 1.0% or more, preferably 1.5% or more, and more preferably 2.0% or more. On the other hand, the strain A is, for example, 20.0% or less, preferably 15.0% or less, and more preferably 10.0% or less. The strain A is, for example, 1.0% or more and 20.0% or less, preferably 1.5% or more and 15.0% or less, and more preferably 2.0% or more and 10% or less. The strain A can be adjusted by the material and thickness of the hard coat layer.

[0032] The strain B when the optical laminate breaks in a tensile test is not particularly limited as long as it satisfies the above-mentioned X1 value range, but is, for example, 3.0% or more, preferably 4.0% or more, and more preferably 5.0% or more. On the other hand, the strain B is, for example, 30.0% or less, 25.0% or less, and preferably 20.0% or less. The strain B is, for example, 3.0% or more and 30.0% or less, preferably 4.0% or more and 25.0% or less, and more preferably 5.0% or more and 20% or less. The strain B can be adjusted by the material and thickness of the resin substrate.

[0033] The tensile modulus C of the optical laminate in the strain range of 1% to 2% is not particularly limited as long as it satisfies the above-mentioned X1 value range, but is, for example, 3.0 GPa or more, preferably 3.3 GPa or more, and more preferably 3.5 GPa or more. On the other hand, the tensile modulus C is, for example, 7.0 GPa or less, preferably 6.0 GPa or less, and more preferably 5.0 GPa or less. The tensile modulus C is, for example, 3.0 GPa or more to 7.0 GPa or less, preferably 3.3 GPa or more to 6.0 GPa or less, and more preferably 3.3 GPa or more to 5.0 GPa or less. By having the tensile modulus C in the above range, the surface hardness and flex resistance can be improved. The tensile modulus C can be adjusted by the material and thickness of the resin substrate and the material and thickness of the hard coat layer.

[0034] The thickness D of the optical laminate is not particularly limited as long as it satisfies the above-mentioned X1 value range, but is, for example, 120 μm or less, preferably 110 μm or less, and more preferably 100 μm or less. When the thickness of the optical laminate is within the above range, it is possible to improve bending resistance. On the other hand, the thickness D of the optical laminate is, for example, 40 μm or more, preferably 50 μm or more, and more preferably 60 μm or more. When the thickness of the optical laminate is within the above range, it is possible to increase the impact resistance and the surface hardness of the surface of the optical laminate on the hard coat layer side. The thickness D of the optical laminate is, for example, 40 μm or more and 120 μm or less, preferably 50 μm or more and 110 μm or less, and more preferably 60 μm or more and 100 μm or less.

[0035] The strain A when a crack occurs in the hard coat layer in a tensile test, the strain B when the optical laminate breaks in a tensile test, and the tensile modulus C of the optical laminate in the strain range of 1% to 2% can be determined by performing the following tensile test on the optical laminate. Figure 3 is a schematic diagram illustrating a method for preparing a sample for the tensile test. Figure 4 is a schematic diagram illustrating the tensile test.

[0036] <Measurement method> Step 1) As shown in FIG. 3(a), the optical laminate 10 is cut into a sample S of 100 mm x 10 mm. Step 2) As shown in Figure 3(b), three sheets of cellophane tape T manufactured by Nichiban Co., Ltd. are stacked and cut into pieces of 30 mm x 5 mm. Two pieces of this tape 41 are prepared. Step 3) As shown in Figures 3(c) and 3(d), two cut pieces of tape 41 are attached to the optical laminate sample S with a gap of 50 mm between them, and folded back to form a handle. Step 4) As shown in Figure 4(a), chuck the handle and adjust the tensile load to 1N. Step 5) Using a tensile tester, start the test under the following measurement conditions: The tensile tester used is Shimadzu Corporation's "AUTOGRAPH AG-X." Step 6) As shown in Figure 4(b), the test area is illuminated with an LED light and observed. The distance La (mm) at which a crack appears in the hard coat layer of the sample is recorded, and the strain A is calculated using the following formula. Strain A = ((La-50) / 50) x 100 (%) Step 7) As shown in Figure 4(c), record the distance Lb (mm) when the entire sample breaks, and calculate the strain B using the following formula. Strain B = ((Lb-50) / 50) x 100 (%) Step 8) On the stress-strain curve, the slope between the two points of stress at 1% strain and stress at 2% strain is taken as the tensile modulus of elasticity C.

[0037] <Measurement conditions> Measurement mode: Tensile mode Load cell load: 1kN Tensile speed: 10 mm / min Chuck distance: 50mm Measurement environment: temperature 23±2℃, humidity 50±10%RH

[0038] 2. X2 value calculated using formula (2) In the optical laminate of the present disclosure, when the composite elastic modulus of the hard coat layer is E (GPa), the composite elastic modulus of the resin substrate is F (GPa), and the thickness of the hard coat layer is G (μm), the X2 value calculated by the following formula (2) is preferably 10 or more. X2=E 2 ×F 2 ×G / 1000 (2)

[0039] In the present disclosure, by ensuring that the X1 value is within a predetermined range and the X2 value is within the above range, it is possible to further increase the surface hardness while maintaining good flex resistance.

[0040] The X2 value is preferably at least 10, more preferably at least 15, and even more preferably at least 20. On the other hand, the X2 value is, for example, at most 80, preferably at most 75, and more preferably at most 70. If the X2 value is too high, the flex resistance may decrease.

[0041] The composite elastic modulus E of the hard coat layer is, for example, preferably 4.0 GPa or more, more preferably 5.0 GPa or more, and even more preferably 6.0 GPa or more. When the composite elastic modulus of the hard coat layer is within the above range, the surface hardness of the hard coat layer side of the optical laminate can be increased, thereby improving scratch resistance. On the other hand, the composite elastic modulus of the hard coat layer is, for example, preferably 10.0 GPa or less, more preferably 9.0 GPa or less, and even more preferably 8.0 GPa or less. If the composite elastic modulus of the hard coat layer is too high, the hardness becomes too high, making it difficult to bend, and there is a risk of a decrease in bending resistance, particularly dynamic bending resistance. The composite elastic modulus of the hard coat layer is, for example, preferably 4.0 GPa or more and 10.0 GPa or less, more preferably 5.0 GPa or more and 9.0 GPa or less, and even more preferably 6.0 GPa or more and 8.0 GPa or less.

[0042] Here, the composite elastic modulus E of the hard coat layer is calculated by the indentation hardness (H IT) is measured. "Indentation hardness" is a value determined from the load-displacement curve from loading to unloading of the indenter, obtained by hardness measurement using the nanoindentation method. The composite elastic modulus of the hard coat layer is an elastic modulus that includes the elastic deformation of the hard coat layer and the elastic deformation of the indenter.

[0043] Indentation hardness (H IT The measurement of the hardness is performed on a measurement sample using a BRUKER TI950 TriboIndenter. Specifically, a 1 mm x 10 mm optical laminate is first embedded in an embedding resin to prepare a block, and a uniform, hole-free slice with a thickness of 50 nm to 100 nm is cut from this block using a general slice preparation method. An Ultramicrotome EM UC7 (Leica Microsystems) or the like can be used to prepare the slices. The remaining block from which the uniform, hole-free slices have been cut serves as the measurement sample. Next, a Berkovich indenter (triangular pyramid, BRUKER TI-0039) is pressed vertically into the center of the cross section of the hard coat layer for 10 seconds up to a maximum load of 25 μN under the following measurement conditions: Here, in order to avoid the influence of adjacent layers and the influence of the side edges of the hard coat layer, the Berkovich indenter is pressed into a portion of the hard coat layer 500 nm away from the interface between the hard coat layer and an adjacent layer (e.g., a resin substrate or an intermediate layer) toward the center of the hard coat layer, and 500 nm away from each of the two ends of the hard coat layer toward the center of the hard coat layer. After that, the pressure is held constant to relax the residual stress, and then the pressure is released over 10 seconds, and the maximum load after relaxation is measured, and this maximum load P max (μN) and contact projection area A p (nm 2 ) and P max / A p The indentation hardness (H ITThe above contact projected area is the contact projected area corrected for the indenter tip curvature by the Oliver-Pharr method using a standard sample of fused quartz (5-0098 manufactured by BRUKER). Indentation hardness (H IT ) is the arithmetic mean value obtained by measuring at 10 locations. If any of the measured values ​​deviate from the arithmetic mean value by more than ±20%, those measured values ​​are excluded and remeasured. Whether or not any of the measured values ​​deviate from the arithmetic mean value by more than ±20% is determined by whether the value (%) calculated by (ab) / b x 100, where a is the measured value and b is the arithmetic mean, is more than ±20%.

[0044] <Measurement condition 1> ·Loading speed: 2.5μN / sec ·Holding time: 5 seconds ·Load unloading speed: 2.5μN / sec ·Measurement temperature: 25℃

[0045] When measuring indentation hardness under the above measurement condition 1, if the indentation depth at the maximum load is 500 nm or more, the measurement is performed under the following measurement condition 2. As described above, in measuring indentation hardness, the hard coat layer is indented for 10 seconds, so the maximum load under measurement condition 1 is 25 μN, and the maximum load under measurement condition 2 is 5 μN.

[0046] <Measurement condition 2> ·Loading speed: 0.5μN / sec ·Holding time: 5 seconds ·Load unloading speed: 0.5μN / sec ·Measurement temperature: 25℃

[0047] The composite elastic modulus E of the hard coat layer is calculated by the following formula (1) using the contact projected area A obtained when measuring the indentation hardness. p The composite elastic modulus E calculated using r The composite elastic modulus E was calculated by measuring the indentation hardness at 10 points and calculating the composite elastic modulus E each time. r The composite elastic modulus Er The arithmetic mean value of

[0048]

number

[0049] The composite elastic modulus of the hard coat layer can be adjusted by the type and composition of the material contained in the hard coat layer.

[0050] The composite elastic modulus F of the resin substrate is, for example, preferably 3.0 GPa or more, more preferably 3.5 GPa or more, and even more preferably 4.0 GPa or more. When the composite elastic modulus of the resin substrate is within the above range, the surface hardness of the surface on the hard coat layer side of the optical laminate can be increased, thereby improving scratch resistance. On the other hand, the composite elastic modulus F of the resin substrate is, for example, preferably 20.0 GPa or less, more preferably 15.0 GPa or less, and even more preferably 10.0 GPa or less. If the composite elastic modulus of the resin substrate is too high, the hardness becomes too high, making it difficult to bend, and there is a risk of a decrease in bending resistance, particularly dynamic bending resistance. The composite elastic modulus F of the resin substrate is, for example, preferably 3.0 GPa or more and 20.0 GPa or less, more preferably 3.5 GPa or more and 15.0 GPa or less, and even more preferably 4.0 GPa or more and 10.0 GPa or less.

[0051] The method for measuring the composite elastic modulus of the resin substrate is the same as the method for measuring the composite elastic modulus of the hard coat layer described above.

[0052] The composite elastic modulus of the resin substrate can be adjusted by the type and composition of the materials contained in the resin substrate.

[0053] The thickness G (μm) of the hard coat layer is not particularly limited as long as it is a thickness that results in the thickness D of the optical laminate satisfying the above formula (1), but is, for example, 3 μm or more, preferably 5 μm or more, and more preferably 10 μm or more. When the thickness of the hard coat layer is within the above range, the surface hardness of the surface on the hard coat layer side of the optical laminate can be increased, and scratch resistance can be improved. On the other hand, the thickness of the hard coat layer is, for example, 50 μm or less, preferably 40 μm or less, and more preferably 30 μm or less. When the thickness of the hard coat layer is within the above range, flex resistance is improved. The thickness of the hard coat layer is, for example, 3 μm or more and 50 μm or less, preferably 5 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less.

[0054] Here, the thickness of each layer is the arithmetic mean value of the thicknesses of 10 arbitrary locations measured on a cross section of the optical laminate in the thickness direction observed with a scanning electron microscope (SEM). The specific method for taking cross-sectional photographs is as follows: First, the optical laminate is cut into a 2 cm x 2 cm block, and the optical laminate is embedded in an embedding resin to create a block. A cross section is then prepared using a polishing machine. A TegraPol-35 manufactured by Struers can be used as the polishing machine. Then, a cross-sectional photograph of the measurement sample is taken using a scanning electron microscope. A Hitachi High-Technologies S-4800 can be used as the scanning electron microscope. When taking cross-sectional photographs using a scanning electron microscope (Hitachi High-Technologies S-4800), the cross section is observed by setting the detector to "Lower," the accelerating voltage to "3 kV," and the emission current to "10 μA." The magnification is adjusted appropriately within the range of 100x to 100,000x, preferably 1,000x to 50,000x, and more preferably 5,000x to 10,000x, by adjusting the focus and observing whether the individual layers can be distinguished in terms of contrast and brightness. When taking cross-sectional photographs using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation), the beam monitor aperture may be set to "1," the objective lens aperture to "3," and the working distance to "8 mm." The contrast of the interface may be difficult to discern at high magnifications. In such cases, observations may be made at low magnifications as well. For example, observations may be made at two magnifications, such as 2,000x and 10,000x, or 5,000x and 20,000x. The arithmetic mean values ​​of the cross-sectional photographs at both magnifications are then calculated, and these mean values ​​are used as the thickness of each layer. If the interface is difficult to discern, it may be possible to visualize it by staining it with a staining agent. Unless otherwise specified, the same applies to the method of measuring the thickness of other layers in the optical laminate.

[0055] 3. Layer structure of optical laminate 1 and 2 are schematic cross-sectional views showing an example of an optical laminate according to the present disclosure. As shown in Fig. 1 and Fig. 2, the optical laminate 10 has a resin substrate 1 and a hard coat layer 2. Furthermore, as shown in Fig. 2(a) and Fig. 2(b), the optical laminate 10 preferably has an intermediate layer 3 between the resin substrate 1 and the hard coat layer 2.

[0056] (1) Resin substrate The resin substrate in the present disclosure is a member that supports the hard coat layer.

[0057] (a) Characteristics of resin substrate When the optical laminate of the present disclosure is used in, for example, a display device, the resin substrate preferably has transparency. Specifically, the total light transmittance of the resin substrate is preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more. The total light transmittance is measured in accordance with JIS K7361-1:1997. Specifically, the total light transmittance can be measured using a haze meter HM150 manufactured by Murakami Color Research Laboratory.

[0058] The haze of the resin substrate is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less. The haze is measured in accordance with JIS K-7136:2000. Specifically, the haze can be measured using a haze meter HM150 manufactured by Murakami Color Research Laboratory.

[0059] (b) Resin substrate material The resin constituting the resin substrate preferably satisfies the above-mentioned composite elastic modulus and has transparency. Examples of such resins include polyamide-based resins, polyester-based resins, cellulose-based resins, acrylic-based resins, polyimide-based resins, and polycarbonate-based resins. Examples of polyester-based resins include polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate (PEN). Examples of cellulose-based resins include triacetyl cellulose (TAC). Examples of acrylic-based resins include polymethyl(meth)acrylate and polyethyl(meth)acrylate. Examples of polyimide-based resins include polyimide, polyamideimide, polyetherimide, and polyesterimide. The resin substrate may be a single layer or a multilayer structure such as a coextruded film.

[0060] From the viewpoint of reducing the environmental load, it is preferable that the resin substrate does not contain fluorine. Generally, a resin substrate made of a polyimide resin contains fluorine to increase the transparency of the resin substrate. Therefore, examples of resin substrates that do not contain fluorine include resin substrates made of resins other than polyimide resins. Among them, polyester resins are preferable as resins that constitute the resin substrate. Furthermore, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferable, and polyethylene naphthalate (PEN) is more preferable. This is because the composite elastic modulus of the resin substrate is high.

[0061] The thickness of the resin substrate is not particularly limited as long as it is a thickness that results in a thickness D of the optical laminate that satisfies the above formula (1), and is, for example, 20 μm or more and 80 μm or less.

[0062] (2) Hard Coat Layer The hard coat layer in the present disclosure is a layer for increasing the surface hardness, and by disposing the hard coat layer, scratch resistance can be improved.

[0063] (a) Characteristics of the hard coat layer Here, the "hard coat layer" refers to a member for increasing the surface hardness, and specifically refers to an optical laminate according to the present disclosure that exhibits a hardness of "H" or higher when subjected to a pencil hardness test specified in JIS K5600-5-4:1999.

[0064] The pencil hardness of the surface on the hard coat layer side of the optical laminate according to the present disclosure is preferably H or more, more preferably 2H or more, even more preferably 3H or more, particularly preferably 4H or more, and most preferably 5H or more. Such an optical laminate has a surface hardness sufficient for use as a laminate disposed on the surface of a display device.

[0065] Here, the pencil hardness is measured by the pencil hardness test specified in JIS K5600-5-4:1999. Specifically, using a test pencil specified in JIS S6006:2020, the pencil hardness test specified in JIS K5600-5-4:1999 is performed on the surface of the hard coat layer side of the optical laminate, and the highest pencil hardness that does not cause scratches is evaluated. The measurement conditions are an angle of 45°, a load of 750 g, a speed of 1 mm / sec, and a temperature of 23±2°C. As a pencil hardness tester, for example, a pencil scratch coating hardness tester manufactured by Toyo Seiki Co., Ltd. can be used.

[0066] (b) Hard Coat Layer Structure The hard coat layer may be a single layer or may have a multi-layer structure of two or more layers. When the hard coat layer has a multi-layer structure, in order to improve the surface hardness and to achieve a good balance between the flex resistance and the elastic modulus, the hard coat layer may have a layer for satisfying the pencil hardness and a layer for satisfying the dynamic flex test (a layer for satisfying the abrasion resistance).

[0067] (c) Hard Coat Layer Material Examples of materials for the hard coat layer include cured resins. Specifically, the hard coat layer preferably contains a cured resin composition containing a polymerizable compound. The cured resin composition containing a polymerizable compound can be obtained by polymerizing the polymerizable compound using a polymerization initiator as needed, using a known method.

[0068] (i) Polymerizable compound The polymerizable compound has at least one polymerizable functional group in the molecule, and may be, for example, at least one of a radical polymerizable compound and a cation polymerizable compound.

[0069] The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of the radical polymerizable compound is not particularly limited as long as it is a functional group capable of causing a radical polymerization reaction, and examples thereof include groups containing a carbon-carbon unsaturated double bond, and specific examples thereof include a vinyl group and a (meth)acryloyl group. When the radical polymerizable compound has two or more radical polymerizable groups, these radical polymerizable groups may be the same or different.

[0070] The number of radically polymerizable groups that the radically polymerizable compound has in one molecule is preferably 2 or more, more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer.

[0071] Among radical polymerizable compounds, compounds having a (meth)acryloyl group are preferred in terms of high reactivity. For example, polyfunctional (meth)acrylate monomers and oligomers having several (meth)acryloyl groups in the molecule and molecular weights of several hundred to several thousand, such as urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, melamine (meth)acrylate, polyfluoroalkyl (meth)acrylate, and silicone (meth)acrylate, are preferably used. Polyfunctional (meth)acrylate polymers having two or more (meth)acryloyl groups in the side chains of the acrylate polymer are also preferably used. Among these, polyfunctional (meth)acrylate monomers having two or more (meth)acryloyl groups in one molecule are preferably used. By including a cured product of a polyfunctional (meth)acrylate monomer in the hard coat layer, the hardness of the hard coat layer can be improved, and adhesion can also be improved. Also, polyfunctional (meth)acrylate oligomers or polymers having two or more (meth)acryloyl groups in one molecule can be preferably used. When the hard coat layer contains a cured product of the polyfunctional (meth)acrylate oligomer or polymer, the hardness and flex resistance of the hard coat layer can be improved, and further, the adhesion can be improved.

[0072] In this specification, (meth)acryloyl refers to both acryloyl and methacryloyl, and (meth)acrylate refers to both acrylate and methacrylate.

[0073] Specific examples of polyfunctional (meth)acrylate monomers include those described in JP-A-2019-132930. Among these, from the viewpoints of high reactivity, improved hardness of the hard coat layer, and adhesion, those having 3 to 6 (meth)acryloyl groups in one molecule are preferred. For example, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane tri(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, etc. can be preferably used, and in particular, at least one selected from pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexaacrylate, and those modified with PO, EO, or caprolactone is preferred.

[0074] The resin composition may contain a monofunctional (meth)acrylate monomer as a radical polymerizable compound to adjust hardness and viscosity, improve adhesion, etc. Specific examples of the monofunctional (meth)acrylate monomer include those described in JP 2019-132930 A.

[0075] The cationically polymerizable compound is a compound having a cationically polymerizable group. The cationically polymerizable group of the cationically polymerizable compound is not particularly limited as long as it is a functional group capable of causing a cationic polymerization reaction, and examples thereof include an epoxy group, an oxetanyl group, and a vinyl ether group. When the cationically polymerizable compound has two or more cationically polymerizable groups, these cationically polymerizable groups may be the same or different.

[0076] The number of cationically polymerizable groups that the cationically polymerizable compound has in one molecule is preferably 2 or more, more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer.

[0077] Among the cationically polymerizable compounds, compounds having at least one of an epoxy group and an oxetanyl group as the cationically polymerizable group are preferred, and compounds having two or more of at least one of an epoxy group and an oxetanyl group per molecule are more preferred. Cyclic ether groups such as epoxy groups and oxetanyl groups are preferred because they cause minimal shrinkage during polymerization. Among cyclic ether groups, compounds having an epoxy group are readily available in a variety of structures, do not adversely affect the durability of the resulting hard coat layer, and are advantageous in that their compatibility with radically polymerizable compounds is easily controlled. Among cyclic ether groups, oxetanyl groups have a higher degree of polymerization and lower toxicity than epoxy groups. When the resulting hard coat layer is combined with a compound having an epoxy group, they accelerate the network formation rate from the cationically polymerizable compound in the coating film, forming an independent network without leaving unreacted monomers in the film, even in regions where the radically polymerizable compound coexists.

[0078] Examples of the cationically polymerizable compound having an epoxy group include alicyclic epoxy resins obtained by epoxidizing polyglycidyl ethers of polyhydric alcohols having an alicyclic ring or cyclohexene ring- or cyclopentene ring-containing compounds with a suitable oxidizing agent such as hydrogen peroxide or peracid; aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts, polyglycidyl esters of aliphatic long-chain polybasic acids, and glycidyl (meth)acrylate homopolymers and copolymers; and glycidyl ether-type epoxy resins derived from bisphenols, such as bisphenol A, bisphenol F, and hydrogenated bisphenol A, or derivatives thereof, such as alkylene oxide adducts or caprolactone adducts, and novolac epoxy resins.

[0079] Specific examples of alicyclic epoxy resins, glycidyl ether epoxy resins, and cationically polymerizable compounds having an oxetanyl group include those described in JP 2018-104682 A. Note that the cured product of the resin composition containing the polymerizable compound contained in the hard coat layer can be analyzed using a Fourier transform infrared spectrophotometer (FTIR) or a pyrolysis gas chromatograph (GC-MS), and decomposition products of the polymer can be analyzed using a combination of high performance liquid chromatography, a gas chromatograph mass spectrometer, NMR, elemental analysis, XPS / ESCA, and TOF-SIMS.

[0080] (ii) Polymerization initiator The resin composition may contain a polymerization initiator as needed. The polymerization initiator may be appropriately selected from radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, etc. These polymerization initiators are decomposed by at least one of light irradiation and heating to generate radicals or cations, thereby promoting radical polymerization and cationic polymerization. Note that in some cases, the polymerization initiator may be completely decomposed and not remain in the hard coat layer.

[0081] Specific examples of radical polymerization initiators and cationic polymerization initiators include those described in JP-A-2018-104682.

[0082] (iii) particles The hard coat layer preferably contains inorganic or organic particles, more preferably inorganic fine particles, which can improve the hardness of the hard coat layer.

[0083] Examples of inorganic particles include metal oxide particles such as silica (SiO), aluminum oxide, zirconia, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide; metal fluoride particles such as magnesium fluoride and sodium fluoride; metal particles; metal sulfide particles; and metal nitride particles. Among these, metal oxide particles are preferred, and at least one selected from silica particles and aluminum oxide particles is more preferred, with silica particles being even more preferred because excellent hardness can be obtained.

[0084] The inorganic particles are preferably reactive inorganic particles having, at least on a part of their surface, photoreactive reactive functional groups capable of forming covalent bonds by crosslinking with each other or with at least one polymerizable compound. The hardness of the hard coat layer can be further improved by crosslinking with each other or with at least one of a radical polymerizable compound and a cation polymerizable compound.

[0085] The reactive inorganic particles have at least a portion of their surface coated with an organic component and have reactive functional groups on their surface introduced by the organic component. Examples of the reactive functional groups include polymerizable unsaturated groups, and more preferably photocurable unsaturated groups. Examples of the reactive functional groups include ethylenically unsaturated bonds such as (meth)acryloyl groups, vinyl groups, and allyl groups, and epoxy groups.

[0086] The reactive silica particles are not particularly limited, and conventionally known ones can be used, such as the reactive silica particles described in JP 2008-165040 A. Commercially available reactive silica particles include MIBK-SD, MIBK-SDMS, MIBK-SDL, and MIBK-SDZL manufactured by Nissan Chemical Industries, Ltd., and V8802 and V8803 manufactured by JGC Catalysts and Chemicals, Ltd.

[0087] The average particle size of the inorganic particles is preferably 5 nm or more, more preferably 10 nm or more, from the viewpoint of improving hardness. If the average particle size of the inorganic particles is too small, it may be difficult to produce the particles and the particles may be prone to agglomeration. Furthermore, from the viewpoint of transparency, the average particle size of the inorganic particles is preferably 200 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less. If the average particle size of the inorganic particles is too large, there is a risk that large irregularities may be formed in the hard coat layer or that the haze may be high.

[0088] Here, the particle size of the inorganic particles is measured by observing the cross section of the hard coat layer with an electron microscope. The average particle size of the inorganic particles is defined as the average particle size of 10 arbitrarily selected particles.

[0089] The hardness of the hard coat layer can be controlled by adjusting the size and content of the inorganic particles. For example, the content of silica particles is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 50 parts by mass or more, relative to 100 parts by mass of the polymerizable compound. When the content of silica particles is within the above range, the hardness of the hard coat layer can be increased. Furthermore, the content of silica particles is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less, relative to 100 parts by mass of the polymerizable compound. When the content of silica particles is within the above range, good flex resistance can be obtained. For example, the content of silica particles is preferably 25 parts by mass or more and 150 parts by mass or less, more preferably 30 parts by mass or more and 120 parts by mass or less, and even more preferably 50 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the polymerizable compound.

[0090] (iv) ultraviolet absorber The hard coat layer may contain an ultraviolet absorber, which can suppress ultraviolet degradation of the resin substrate. Furthermore, in a display device including the optical laminate, ultraviolet degradation of components arranged closer to the display panel than the optical laminate, such as a polarizer, can be suppressed.

[0091] The ultraviolet absorber contained in the hard coat layer preferably has an absorption wavelength peak in absorbance measurement of 300 nm to 390 nm, more preferably 320 nm to 370 nm, and even more preferably 330 nm to 370 nm. This is because such an ultraviolet absorber can efficiently absorb ultraviolet rays in the UVA region, and can form a hard coat layer having ultraviolet absorbing ability without causing curing inhibition of the hard coat layer by shifting the peak wavelength from the absorption wavelength of 250 nm of the initiator for curing the hard coat layer.

[0092] Among them, it is preferable that the ultraviolet absorber has an absorption wavelength peak of 380 nm or less, since coloring caused by the ultraviolet absorber can be suppressed.

[0093] The absorbance of the ultraviolet absorber is measured using an ultraviolet-visible-near infrared spectrophotometer (for example, "V-7100" manufactured by JASCO Corporation).

[0094] Examples of the ultraviolet absorber include triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers such as hydroxybenzophenone-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers.

[0095] Among them, from the viewpoint of suppressing deterioration of the resin substrate due to ultraviolet rays, one or more ultraviolet absorbers selected from the group consisting of hydroxybenzophenone-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are preferred, and one or more ultraviolet absorbers selected from the group consisting of hydroxybenzophenone-based ultraviolet absorbers are more preferred. Specific examples of hydroxybenzophenone-based ultraviolet absorbers include those described in JP-A-2019-132930.

[0096] The content of the ultraviolet absorber in the hard coat layer is, for example, preferably 10% by mass or less, more preferably 7% by mass or less, from the viewpoint of suppressing haze caused by mixing the ultraviolet absorber. Also, from the viewpoint of suppressing deterioration of the resin substrate due to ultraviolet rays and improving durability, the content of the ultraviolet absorber in the hard coat layer is preferably 1% by mass or more and 6% by mass or less, more preferably 2% by mass or more and 5% by mass or less.

[0097] (v) antifouling agent The hard coat layer may contain an antifouling agent, which can impart antifouling properties to the optical laminate.

[0098] The antifouling agent is not particularly limited, and examples thereof include silicone-based antifouling agents, fluorine-based antifouling agents, and silicone-based and fluorine-based antifouling agents. The antifouling agent may also be an acrylic-based antifouling agent. One type of antifouling agent may be used alone, or two or more types may be mixed and used.

[0099] A hard coat layer containing a silicone-based antifouling agent or a fluorine-based antifouling agent is resistant to fingerprints (less noticeable) and has good wiping properties. Furthermore, when a silicone-based antifouling agent or a fluorine-based antifouling agent is contained, the surface tension of the curable resin composition for a hard coat layer can be reduced during application, resulting in good leveling properties and a good appearance of the resulting hard coat layer.

[0100] Furthermore, a hard coat layer containing a silicone-based antifouling agent has good slipperiness and good scratch resistance. Furthermore, a hard coat layer containing a silicone-based antifouling agent is preferable in terms of environmental considerations, as described below, compared to a hard coat layer containing a fluorine-based antifouling agent. A display device including a display device member having a hard coat layer containing such a silicone-based antifouling agent has good slipperiness when touched with a finger, a pen, or the like, resulting in a good tactile feel.

[0101] The antifouling agent preferably has a reactive functional group in order to improve the durability of the antifouling performance. If the antifouling agent does not have a reactive functional group, regardless of whether the laminate is in the form of a roll or a sheet, when the laminate is stacked, the antifouling agent will be transferred to the surface opposite to the hard coat layer side of the laminate, and when another layer is attached or applied to the surface opposite to the hard coat layer side of the laminate, the other layer may peel off, and further, the other layer may be more likely to peel off when repeatedly bent. In contrast, when the antifouling agent has a reactive functional group, the antifouling performance will be more durable.

[0102] The number of reactive functional groups in the antifouling agent may be at least 1, and preferably at least 2. By using an antifouling agent having two or more reactive functional groups, it is possible to impart excellent scratch resistance to the hard coat layer.

[0103] The antifouling agent preferably has a weight-average molecular weight of not more than 5000. The weight-average molecular weight of the antifouling agent can be measured by gel permeation chromatography (GPC).

[0104] The antifouling agent may be uniformly dispersed in the hard coat layer, but from the viewpoint of obtaining sufficient antifouling properties with a small amount added and suppressing a decrease in the strength of the hard coat layer, it is preferable that the antifouling agent be unevenly distributed on the surface side of the hard coat layer.

[0105] Examples of methods for unevenly distributing the antifouling agent on the surface side of the hard coat layer include a method in which, when forming the hard coat layer, a coating film of a curable resin composition for a hard coat layer is dried and heated before being cured to reduce the viscosity of the resin component contained in the coating film, thereby increasing the fluidity and thereby unevenly distributing the antifouling agent on the surface side of the hard coat layer; and a method in which an antifouling agent with low surface tension is used, and the antifouling agent is floated on the surface of the coating film without applying heat when drying the coating film, and then the coating film is cured, thereby unevenly distributing the antifouling agent on the surface side of the hard coat layer.

[0106] The content of the antifouling agent is preferably, for example, 0.01 to 3.0 parts by mass per 100 parts by mass of the resin component. If the content of the antifouling agent is too low, sufficient antifouling properties may not be imparted to the hard coat layer, whereas if the content of the antifouling agent is too high, the hardness of the hard coat layer may decrease.

[0107] (vi) Other additives The hard coat layer may further contain additives as necessary. The additives are appropriately selected depending on the function to be imparted to the hard coat layer, and are not particularly limited, and examples thereof include inorganic or organic particles for adjusting the refractive index, infrared absorbers, antiglare agents, antifouling agents, antistatic agents, colorants such as blue pigments and purple pigments, leveling agents, surfactants, lubricants, various sensitizers, flame retardants, adhesion promoters, polymerization inhibitors, antioxidants, light stabilizers, and surface modifiers.

[0108] (d) Method for forming a hard coat layer The method for forming the hard coat layer is appropriately selected depending on the material of the hard coat layer, etc., and examples thereof include a method of applying a curable resin composition for a hard coat layer containing the polymerizable compound, etc. to one surface of the resin substrate, and curing the composition. The curable resin composition for a hard coat layer may further contain a solvent, if necessary.

[0109] The method for applying the curable resin composition for a hard coat layer to a resin substrate is not particularly limited as long as it allows application to a desired thickness, and examples thereof include common application methods such as gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, screen printing, etc. Furthermore, a transfer method can also be used as a method for forming a coating film of the resin composition for a hard coat layer.

[0110] The coating film of the curable resin composition for the hard coat layer is dried as needed to remove the solvent. Examples of drying methods include vacuum drying, heat drying, and a combination of these drying methods. For example, the coating film can be dried by heating at a temperature of 30°C to 120°C for 10 to 180 seconds.

[0111] The method for curing the coating film of the curable resin composition for the hard coat layer is appropriately selected depending on the polymerizable group of the polymerizable compound, and for example, at least one of light irradiation and heating can be used.

[0112] For light irradiation, ultraviolet rays, visible light, electron beams, ionizing radiation, etc. are mainly used. In the case of ultraviolet curing, for example, ultraviolet rays emitted from the light beam of an ultra-high pressure mercury lamp, high pressure mercury lamp, low pressure mercury lamp, carbon arc, xenon arc, metal halide lamp, etc. can be used. The irradiation dose of the energy ray source is, for example, 50 mJ / cm as the cumulative exposure dose at an ultraviolet wavelength of 365 nm. 2 More than 5000mJ / cm 2 It is about the following.

[0113] When heating is performed, the treatment can be performed at a temperature of, for example, 40°C or higher and 120°C or lower. Alternatively, the reaction can be performed by leaving it at room temperature (25°C) for 24 hours or more. When heating is performed, the treatment can be performed at a temperature of, for example, 40°C or higher and 120°C or lower. Alternatively, the reaction can be performed by leaving it at room temperature (25°C) for 24 hours or more.

[0114] (3) Middle class As shown in Figures 2(a) and 2(b), the optical laminate according to the present disclosure preferably has an intermediate layer 3 between the resin substrate 1 and the hard coat layer 2. The intermediate layer can improve the adhesion between the resin substrate and the hard coat layer.

[0115] Examples of intermediate layers include a primer layer and a penetration layer. In the optical laminate 10 shown in FIG. 2(a), a primer layer 3A is disposed as an intermediate layer 3 between the resin substrate 1 and the hard coat layer 2. In the optical laminate 10 shown in FIG. 2(b), a penetration layer 3B is disposed as an intermediate layer 3 between the resin substrate 1 and the hard coat layer 2. As will be described later, the penetration layer 3B is a layer formed by the components of the curable resin composition for the hard coat layer penetrating into the region of the resin substrate on the hard coat layer side during the formation of the hard coat layer. Therefore, the penetration layer 3B is a layer containing the components constituting the resin substrate and the components constituting the hard coat layer.

[0116] The intermediate layer is preferably a primer layer. This is because the X1 value is more likely to fall within the above-mentioned range by providing a primer layer. This is for the following reasons: When the intermediate layer is a permeation layer, the permeation layer contains both the components constituting the resin substrate and the components constituting the hard coat layer, thereby enhancing the integrity of the resin substrate and the hard coat layer. On the other hand, when the intermediate layer is a primer layer, the primer layer typically contains a material different from the resin substrate and the hard coat layer, thereby reducing the integrity of the resin substrate and the hard coat layer. Therefore, cracks in the hard coat layer are less likely to affect the breakage of the entire optical laminate. Therefore, (BA) in the above formula (1) tends to be large, and the X1 value is more likely to fall within the above-mentioned range.

[0117] The type of intermediate layer is preferably selected depending on the type of resin substrate. For example, when the resin substrate has low solvent permeability, the components of the curable resin composition for the hard coat layer, particularly the solvent, tend to permeate less. Therefore, in this case, it is preferable to provide a primer layer as the intermediate layer to improve adhesion between the resin substrate and the hard coat layer. Specifically, when the resin substrate contains a polyester-based resin, the permeability of the solvent into the resin substrate tends to be low, so it is preferable to provide a primer layer. On the other hand, when the solvent permeability into the resin substrate is high, the components of the curable resin composition for the hard coat layer, particularly the solvent, tend to permeate more. Therefore, in this case, it is preferable to provide a penetration layer as the intermediate layer to improve adhesion between the resin substrate and the hard coat layer. Specifically, when the resin substrate contains a polyimide-based resin or a cellulose-based resin, the permeability of the solvent into the resin substrate tends to be high, so it is preferable to provide a penetration layer.

[0118] (a) Primer layer As described above, the optical laminate of the present disclosure preferably has a primer layer as an intermediate layer. The material for the primer layer is not particularly limited as long as it is a material that can improve adhesion between the resin substrate and the hard coat layer, and examples thereof include resins. Examples of resins include (meth)acrylic resins, urethane resins, (meth)acrylic urethane copolymers, vinyl chloride-vinyl acetate copolymer resins, polyesters, butyral resins, chlorinated polypropylene, chlorinated polyethylene, epoxy resins, and silicone resins. These resins may be used alone or in combination of two or more.

[0119] The method for forming the primer layer may be, for example, a method of applying a primer layer composition to one surface of a resin substrate. Examples of the application method include general application methods such as gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, and screen printing. Alternatively, a transfer method may be used to form the primer layer.

[0120] The thickness of the primer layer is, for example, 0.01 μm or more, preferably 0.02 μm or more, and more preferably 0.05 μm or more. By setting the thickness of the primer layer within the above range, adhesion between the resin substrate and the hard coat layer can be ensured. The thickness of the primer layer is, for example, preferably 0.5 μm or less, more preferably 0.2 μm or less, and even more preferably 0.15 μm or less. By setting the thickness of the primer layer within the above range, interference fringes can be suppressed, and visibility can be improved.

[0121] When the optical laminate according to the present disclosure is used in a display device, it is preferable that the primer layer has a refractive index between the refractive index of the resin substrate and the refractive index of the hard coat layer. This is because the occurrence of interference fringes in the optical laminate can be suppressed, improving the visibility of the display device. In this case, the primer layer also serves as a refractive index adjusting layer.

[0122] The refractive index of the primer layer is not particularly limited as long as it is between the refractive index of the resin substrate and the refractive index of the hard coat layer, but for example, it is preferably 1.40 or more and 1.80 or less, more preferably 1.50 or more and 1.70 or less, and even more preferably 1.55 or more and 1.65 or less.

[0123] The refractive index of the primer layer refers to the refractive index for light with a wavelength of 550 nm. The refractive index can be measured using a microspectrophotometric film thickness meter. An example of a microspectrophotometric film thickness meter is the "OPTM-A1" manufactured by Otsuka Electronics Co., Ltd.

[0124] (b) Penetration layer The optical laminate of the present disclosure may have a permeation layer as an intermediate layer. The permeation layer is a layer formed by the components of the curable resin composition for the hard coat layer permeating into the region of the resin substrate on the hard coat layer side during the formation of the hard coat layer. Therefore, the permeation layer is a layer containing the components constituting the resin substrate and the components constituting the hard coat layer. Therefore, the permeation layer enhances the integrity of the resin substrate and the hard coat layer. Furthermore, since the permeation layer containing the components constituting the resin substrate and the components constituting the hard coat layer is present between the resin substrate and the hard coat layer, a sudden change in refractive index is eliminated, and the occurrence of interference fringes due to the refractive index difference can be suppressed.

[0125] The components of the curable resin composition for the hard coat layer that penetrate into the resin substrate are, for example, a polymerizable compound and a solvent. That is, the components that constitute the hard coat layer contained in the intermediate layer are, for example, a cured product of a resin composition containing a polymerizable compound. Specifically, the penetration layer contains a cured product of a resin composition containing a polymerizable compound and a resin component that constitutes the resin substrate.

[0126] When a permeation layer is provided, as described above, the resin substrate preferably contains a polyimide resin or a cellulose resin, and preferably contains a polyimide resin. Resin substrates containing polyimide resins tend to have lower solvent permeability than resin substrates containing cellulose resins. Furthermore, the higher the solvent permeability, the thicker the permeation layer tends to be, while the lower the solvent permeability, the thinner the permeation layer tends to be. Therefore, as described below, considering the thickness of the permeation layer, polyimide resins are preferred.

[0127] The thickness of the penetration layer is, for example, 0.01 μm or more, preferably 0.05 μm or more, and more preferably 0.1 μm or more. By setting the thickness of the penetration layer within the above range, sufficient adhesion between the resin substrate and the hard coat layer can be ensured. On the other hand, the thickness of the penetration layer is, for example, 2.0 μm or less, preferably 1.5 μm or less, and more preferably 1.0 μm or less. If the thickness of the penetration layer is too thick, the integrity between the resin substrate and the hard coat layer will be higher, making cracks in the hard coat layer more likely to affect the breakage of the entire optical laminate. Therefore, (BA) in the above formula (1) tends to be smaller. In other words, by setting the thickness of the penetration layer within the above range, the integrity between the resin substrate and the hard coat layer will not be too high, so (BA) in the above formula (1) tends to be larger, and the X1 value is likely to be within the above range.

[0128] (4) Anti-reflection layer 2(c), the optical laminate according to the present disclosure preferably has an antireflection layer 4 on the surface of the hard coat layer 2 opposite to the resin substrate 1. Note that, since the antireflection layer is usually thin, its influence on the above-mentioned parameters such as the distortion of the optical laminate, the tensile modulus of the optical laminate, the thickness of the optical laminate, and the Young's modulus of the optical laminate is extremely small and negligible.

[0129] The thickness of the antireflection layer is, for example, 0.5 μm or less, more preferably 0.2 μm or less, and particularly preferably 0.15 μm or less, while the thickness of the antireflection layer is, for example, 0.05 μm or more, or may be 0.07 μm or more, or may be 0.08 μm or more.

[0130] The antireflection layer may be a general antireflection layer. Examples of the antireflection layer include a low refractive index layer (single layer film) containing a material with a refractive index lower than that of the hard coat layer, a multilayer film having a high refractive index layer and a low refractive index layer from the hard coat layer side, a multilayer film in which a high refractive index layer and a low refractive index layer are alternately stacked from the hard coat layer side, and a multilayer film having a medium refractive index layer, a high refractive index layer, and a low refractive index layer in this order from the hard coat layer side. From the viewpoint of scratch resistance, a low refractive index layer (single layer film) is preferred. On the other hand, from the viewpoint of optical properties (antireflection properties), a multilayer film is preferred.

[0131] When the antireflection layer is a low refractive index layer (single layer film), the material contained in the single layer film may be a material having a refractive index lower than that of the hard coat layer. Examples of such a low refractive index layer include those containing low refractive index particles, those containing low refractive index resin, those containing binder resin and low refractive index particles, and those containing a hydrolysis polycondensate of metal alkoxide. Among these, it is preferable that the low refractive index layer contains binder resin and low refractive index particles.

[0132] The low refractive index particles are not particularly limited, and for example, inorganic particles such as silica and magnesium fluoride, or organic particles can be used. Among them, particles having voids are preferred from the viewpoint of reducing the reflectance of the anti-reflection layer. Particles having voids have minute voids inside and contain air in the voids, resulting in a low refractive index. Examples of particles having voids include porous particles and hollow particles. Among them, hollow particles are preferred.

[0133] A hollow particle is a particle that has an outer shell layer, and the inside of the particle surrounded by the outer shell layer is hollow and contains air inside the particle.

[0134] The outer shell layer of the hollow particles may be inorganic or organic. Examples include metals, metal oxides, resins, and silica. Among these, hollow silica particles having an outer shell layer made of silica are preferred. When the outer shell layer is made of silica, the silica may be in any of a crystalline, sol-like, or gel-like state.

[0135] The shape of the hollow particles may be any of spherical, spheroidal, and nearly spherical such as a polyhedral shape that approximates a sphere, chain-like, needle-like, plate-like, flake-like, rod-like, fibrous, etc. Of these, spherical and nearly spherical shapes are preferred, and spheroidal or spherical shapes are more preferred.

[0136] When the low refractive index layer contains a binder resin and low refractive index particles, the low refractive index particles are preferably surface-treated. The surface treatment of the low refractive index particles is preferably a surface treatment using a silane coupling agent. Among these, a surface treatment using a silane coupling agent having a (meth)acryloyl group is preferred. By subjecting the low refractive index particles to a surface treatment, the affinity with the binder resin is improved, the particles are uniformly dispersed, and the particles are less likely to aggregate. This makes it possible to suppress a decrease in the transparency of the low refractive index layer due to particle size increase resulting from aggregation, as well as a decrease in the applicability of the composition for the low refractive index layer and a decrease in the coating strength of the composition for the low refractive index layer.

[0137] Examples of silane coupling agents that are preferably used in the surface treatment of low refractive index particles include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilane, Examples of suitable silanes include dimethylsilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, 1,6-bis(trimethoxysilyl)hexane, trifluoropropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0138] The average particle diameter of the low-refractive-index particles is, for example, preferably 5 nm to 200 nm, more preferably 10 nm to 150 nm. Furthermore, when the low-refractive-index particles are hollow particles, the average particle diameter is, for example, preferably 5 nm to 200 nm, more preferably 30 nm to 150 nm, and even more preferably 50 nm to 110 nm. When the average particle diameter is within the above range, the thickness of the low-refractive-index layer can be easily made uniform. Furthermore, by setting the average particle diameter to 5 nm or more, particle aggregation can be easily suppressed, and in the case of hollow particles, the refractive index of the low-refractive-index layer can be easily reduced. Furthermore, by setting the average particle diameter to 200 nm or less, it is possible to easily suppress a decrease in visibility due to whitening caused by particle diffusion.

[0139] The average particle size of the low refractive index particles can be calculated by the following steps (1) to (3). (1) The cross section of the low refractive index layer is imaged by a TEM or STEM. The acceleration voltage of the TEM or STEM is preferably, for example, 10 kV to 30 kV, and the magnification is preferably, for example, 50,000 to 300,000. (2) Randomly extract 10 particles from the observed image and calculate the particle diameter of each particle. The particle diameter is measured as the distance between two parallel lines that maximizes the distance between the two lines when the cross section of the particle is sandwiched between the two lines. (3) Repeat the same procedure five times on a separate image of the same sample, and use the number average of a total of 50 particles as the average particle size.

[0140] When the low refractive index layer contains a binder resin and low refractive index particles, the content of the low refractive index particles is preferably 20 parts by mass to 250 parts by mass, more preferably 30 parts by mass to 230 parts by mass, and even more preferably 40 parts by mass to 200 parts by mass, relative to 100 parts by mass of the binder resin in the low refractive index layer. If the content of the low refractive index particles is within the above range, a good balance between antireflection properties and scratch resistance can be achieved.

[0141] Furthermore, the proportion of hollow particles relative to the total amount of low refractive index particles contained in the low refractive index layer is preferably 40% by mass or more, more preferably 50% by mass or more. By setting the proportion of hollow particles within the above range, the refractive index of the low refractive index layer can be sufficiently reduced, resulting in good anti-reflection properties. Examples of binder resins contained in the low refractive index layer include cured products of curable resin compositions. As the curable resin composition, the same ones as those exemplified for the hard coat layer can be used, and photocurable resin compositions are preferred.

[0142] The hydrolysis polycondensate of metal alkoxide can be obtained by, for example, a sol-gel method. Examples of the resin having a low refractive index include fluororesins.

[0143] The antireflection layer may contain an antifouling agent. Examples of the antifouling agent include those exemplified for the hard coat layer. The content of the antifouling agent in the antireflection layer is preferably, for example, 0.01 parts by mass or more and 20.0 parts by mass or less per 100 parts by mass of the resin component.

[0144] 4. Characteristics of optical laminates (1) Young's modulus The Young's modulus of the optical laminate in the present disclosure is, for example, preferably 4.0 GPa or more, more preferably 4.5 GPa or more. On the other hand, the Young's modulus of the optical laminate is, for example, preferably 7.0 GPa or less, more preferably 6.0 GPa or less. The Young's modulus of the optical laminate is, for example, preferably 4.0 GPa or more and 7.0 GPa or less, more preferably 4.5 GPa or more and 6.0 GPa or less. Having the Young's modulus within the above range can improve surface hardness and flex resistance. The Young's modulus of the optical laminate can be adjusted by the material and thickness of the resin substrate. The Young's modulus of the optical laminate is the slope corresponding to the stress at a tensile load of 5 N and the stress at a tensile load of 20 N in the stress-strain curve obtained in the above-mentioned tensile test.

[0145] (2) Fluorine atom content From the viewpoint of reducing environmental impact, the optical laminate of the present disclosure preferably does not contain fluorine atoms. That is, in the present disclosure, it is preferable that neither the resin substrate nor the hard coat layer constituting the optical laminate contain fluorine atoms. "The optical laminate does not contain fluorine atoms" means that the content of fluorine atoms in the optical laminate is below the detection limit of the combustion ion chromatography measurement device. The detection limit of the combustion ion chromatography measurement device is generally 20 ppm to 50 ppm. An example of the combustion ion chromatography measurement device is the Combustion Ion Chromatography System manufactured by Thermo Fisher Scientific. The fluorine atoms may be derived from either organic fluorine compounds or inorganic fluorine compounds. Examples of organic fluorine compounds include PFAS such as PFOS, PFOA, and PFHxA.

[0146] (3) Total light transmittance and haze When used in a display device, the optical laminate of the present disclosure preferably has transparency. The total light transmittance of the optical laminate of the present disclosure is, for example, preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more. Such a high total light transmittance allows the optical laminate to have good transparency. The total light transmittance is measured in accordance with JIS K7361-1:1997. Specifically, the total light transmittance can be measured using a haze meter HM150 manufactured by Murakami Color Research Laboratory.

[0147] The haze of the optical laminate of the present disclosure is, for example, preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less. Such a low haze allows the optical laminate to have good transparency. Haze is measured in accordance with JIS K-7136:2000. Specifically, haze can be measured using a haze meter HM150 manufactured by Murakami Color Research Laboratory.

[0148] (4) Flexibility The optical laminate of the present disclosure preferably has flex resistance. Specifically, when the optical laminate of the present disclosure is subjected to a dynamic flex test described below, the minimum distance at which the optical laminate does not crack, break, or peel is preferably 4 mm or less, and more preferably 3 mm or less.

[0149] The dynamic bending test is performed as follows. First, a test piece of the optical laminate measuring 20 mm × 100 mm is prepared. Next, as shown in FIG. 5(a), the short side 10P of the optical laminate 10 and the short side 10Q opposite the short side 10P are fixed by parallel fixing parts 100A and 100B, respectively. The optical laminate is fixed so that the hard coat layer side of the optical laminate faces inward when bent. As shown in FIG. 5(a), the fixing parts 100A and 100B are slidable horizontally. Next, as shown in FIGS. 5(b) and 5(c), the fixing parts 100A and 100B are moved closer to each other to bend the optical laminate 10 into a U-shape, and the optical laminate 10 is bent 180° so that the distance d between the opposing short sides 10P and 10Q of the optical laminate 10 is 6 mm. This operation is repeated 200,000 times. After the test, the optical laminate is observed, and if no cracks, breaks, or peeling occurs, the test is repeated by reducing the distance d in 1 mm increments (6 mm → 5 mm → 4 mm → 3 mm → 2 mm) and folding the optical laminate 200,000 times until cracks, breaks, or peeling occurs. The smallest distance at which no cracks, breaks, or peeling occurs in the optical laminate is recorded. For example, if cracks occur when the distance d is 3 mm, the smallest distance at which no cracks, breaks, or peeling occurs is 4 mm.

[0150] <Measurement conditions> Equipment: Yuasa System Co., Ltd. DLDMLH-FS Test speed: 120 r / min Number of flexes: 200,000

[0151] Here, in the dynamic bending test, "cracking" refers to the phenomenon in which a crack occurs in the optical laminate. "Fracture" refers to the phenomenon in which the optical laminate completely breaks into two pieces. "Peeling" refers to the phenomenon in which any layer constituting the optical laminate peels off or lifts off.

[0152] 5.Applications The optical laminate according to the present disclosure is used in a display device member. The display device member is a member disposed on the viewer side of the display panel in a display device. The display device member in which the optical laminate according to the present disclosure is used will be described later.

[0153] B. Display device components The present disclosure provides a member for a display device having the above-described optical laminate. Fig. 6 is a schematic cross-sectional view showing an example of the member for a display device in the present disclosure. The member for a display device 20 has the above-described optical laminate 10. The member for a display device 20 may further have a first functional layer 5 on the surface of the optical laminate 10 facing the resin substrate 12. The member for a display device 20 may further have a second functional layer 6 on the surface of the optical laminate 10 facing the hard coat layer 2.

[0154] 1. Optical laminate The optical laminate is the same as the optical laminate described above.

[0155] 2. 1st functional layer The first functional layer may be a single layer or may have multiple layers. The first functional layer may be a layer having a single function or may have multiple layers having different functions. Examples of the first functional layer disposed on the resin substrate side of the optical laminate include a shatterproof layer and an impact absorbing layer.

[0156] 3.Second functional layer The second functional layer may be a single layer or may have multiple layers. The second functional layer may be a layer having a single function or may have multiple layers having different functions. Examples of the second functional layer disposed on the surface of the optical laminate on the hard coat layer side include an antiglare layer, a protective layer, and an antifouling layer.

[0157] 4.Applications The member for a display device according to the present disclosure can be used as a member disposed on the viewer side of the display panel in a display device.

[0158] In the member for a display device according to the present disclosure, the surface that becomes the outermost surface when the member for a display device is disposed on the surface of the display device is preferably the surface on the hard coat layer side. The method for disposing the member for a display device according to the present disclosure on the surface of the display device is not particularly limited, and examples thereof include a method using an adhesive layer.

[0159] C.Display device A display device according to the present disclosure includes a display panel and the above-described member for a display device, which is disposed on the viewer side of the display panel.

[0160] Fig. 7 is a schematic cross-sectional view showing an example of a display device according to the present disclosure. As shown in Fig. 7, a display device 30 includes a display device member 20 arranged on the viewer side of a display panel 31. In the display device 30, the display device member 20 is used as a member arranged on the surface of the display device 30, and an adhesive layer 32 is arranged between the display device member 20 and the display panel 31. As the adhesive layer, a known adhesive layer used for bonding display device members can be used.

[0161] The member for a display device in the present disclosure is similar to the member for a display device described above.

[0162] Examples of the display panel in the present disclosure include display panels used in display devices such as liquid crystal display devices, organic EL display devices, and LED display devices.

[0163] The display device according to the present disclosure may have a touch panel member between the display panel and the display device member.

[0164] The display device according to the present disclosure is preferably a flexible display such as a foldable display, a rollable display, or a bendable display. Of these, the display device according to the present disclosure is more preferably a foldable display. Since the display device according to the present disclosure includes the above-described display device member, it has excellent bending resistance and is suitable as a flexible display, and further as a foldable display.

[0165] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0166] The present disclosure will be further described below with reference to examples and comparative examples.

[0167] [Example 1] A polyethylene naphthalate (PEN) film was prepared as a resin substrate as follows. Polyethylene naphthalate was melted at 290°C, extruded through a film-forming die into a sheet, and then cooled by contact with a water-cooled rotating quenching drum to produce an unstretched film with a thickness of 100 μm. This unstretched film was preheated at 120°C for 1 minute in a biaxial stretching tester (manufactured by Toyo Seiki Co., Ltd.), and then uniaxially stretched at 2.0 times the fixed end at 120°C to obtain a PEN film with a thickness of 50 μm.

[0168] The primer layer composition described below was applied to one surface of the PEN film so that the film thickness after drying would be 0.1 μm, and dried at 120° C. for 30 seconds to form a primer layer with a thickness of 0.1 μm.

[0169] <Primer layer composition> Amorphous polyester (product name "Vylon 63SS", manufactured by Toyobo Co., Ltd.): 3.85 parts by weight (based on 100% solids) Zirconium oxide (average particle size 20 nm, manufactured by CIK Nanotech): 1.15 parts by weight (based on 100% solids) Methyl isobutyl ketone: 95 parts by weight The above "value converted to 100% solids content" refers to the value when the solids content in the solvent-diluted product is taken as 100%. The same applies hereinafter.

[0170] The following curable resin composition for a hard coat layer was applied onto the primer layer so that the thickness after curing would be as shown in Table 1, and the applied composition was dried at 70°C for 1 minute, followed by irradiation with 200 mJ / cm 2 2 The resulting composition was cured by irradiating it with ultraviolet light at a temperature of 100° C. to form a hard coat layer. This resulted in an optical laminate having the resin substrate, the primer layer (intermediate layer), and the hard coat layer in this order.

[0171] <Curable Resin Composition for Hard Coat Layer> Urethane acrylate (product name "UV-7600B", manufactured by Mitsubishi Chemical Corporation): 100 parts by weight (based on 100% solids) Reactive silica (product name "MIBK-SD", Nissan Chemical Industries): 50 parts by weight (based on 100% solids) Photopolymerization initiator (product name "Omnirad184", IGM Resins BV): 4 parts by mass Leveling agent (product name "BYK-UV 3500", BYK Japan): 0.2 parts by weight Methyl ethyl ketone: 225 parts by weight

[0172] [Examples 2 to 3] An optical layered body was produced in the same manner as in Example 1, except that the thickness of the hard coat layer was changed as shown in Table 1 below.

[0173] [Example 4] A polyimide film was produced as a resin substrate as follows: First, a tetracarboxylic dianhydride represented by the following chemical formula was synthesized with reference to Synthesis Example 1 of WO 2014 / 046180.

[0174] [ka]

[0175] A 500 mL separable flask was purged with nitrogen and a solution containing 293.29 g of dehydrated dimethylacetamide (DMAc) and 14.3 g (44.7 mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was dissolved. The temperature was controlled at 30°C. 24.8 g (40.1 mmol) of tetracarboxylic dianhydride (TMPBPTME) was gradually added so that the temperature did not rise more than 2°C. The mixture was stirred for 3 hours with a mechanical stirrer. 0.91 g (4.5 mmol) of terephthalic acid dichloride (TPC) was then added and stirred for another 3 hours to obtain a polyamic acid solution. Next, 6.66 g (84.2 mmol) of pyridine catalyst and 8.60 g (84.2 mmol) of acetic anhydride were added. The mixture was stirred at 25°C for 30 minutes to confirm the homogeneity of the solution. The mixture was then heated to 70°C and stirred for 1 hour. After cooling to room temperature, 174.26 g of 2-propyl alcohol (IPA) was gradually added to the solution, resulting in a slightly cloudy solution. 435.64 g of IPA was added to the cloudy solution all at once, resulting in a white slurry. The slurry was filtered and washed five times with IPA, then dried in an oven heated to 100°C under reduced pressure for six hours to obtain a polyamideimide powder (37.1 g). The weight-average molecular weight of the polyamideimide measured by GPC was 62,000.

[0176] DMAc was added to polyamideimide to prepare a polyamideimide varnish with a polyamideimide content of 19% by mass. The viscosity of the polyamideimide varnish (solid content of 19% by mass) at 25°C was 4000 mPa·s.

[0177] A polyamideimide varnish (solid content concentration 19% by mass) was applied to a glass plate so that the film thickness after drying in a circulation oven described below would be 50 μm. The plate was then dried in a circulation oven at 120° C. for 10 minutes, cooled to 25° C., and the polyimide resin coating was peeled off.

[0178] The peeled polyimide-based resin coating was cut into a size of 150 mm x 200 mm. The cut polyimide-based resin coating was sandwiched between two metal frames (external dimensions 150 mm x 200 mm, internal dimensions 130 mm x 180 mm), and the metal frames and polyimide-based resin coating were fixed with a fixture. The fixed polyimide-based resin coating was heated to 300°C at a heating rate of 10°C / min in a circulating oven under a nitrogen flow (oxygen concentration 100 ppm or less), held at 300°C for 1 hour, and then cooled to 25°C to produce a single-layer polyimide film.

[0179] The curable resin composition for hard coat layer used in Example 1 was applied to one surface of the polyimide film so that the thickness after curing would be as shown in Table 1, and the applied film was dried at 70°C for 1 minute, followed by irradiation with 200 mJ / cm. 2 The resin was cured by irradiating it with ultraviolet light at a temperature of 100° C. to form a permeation layer and a hard coat layer. This resulted in an optical laminate having the resin substrate, the permeation layer (intermediate layer), and the hard coat layer in this order.

[0180] [Example 5] An optical laminate was produced in the same manner as in Example 4, except that the thickness of the permeation layer (intermediate layer) and the thickness of the hard coat layer were changed as shown in Table 1 below.

[0181] [Example 6] An optical laminate was produced in the same manner as in Example 4, except that the following curable resin composition for hard coat layer was used and the thickness of the hard coat layer was changed as shown in Table 1 below.

[0182] <Curable Resin Composition for Hard Coat Layer> Urethane acrylate (product name "UV-7600B", manufactured by Mitsubishi Chemical Corporation): 100 parts by weight (based on 100% solids) Photopolymerization initiator (product name "Omnirad184", IGM Resins BV): 4 parts by mass Silicone leveling agent (product name "BYK-UV 3500", BYK Japan): 0.2 parts by weight Methyl ethyl ketone: 75 parts by weight Methyl isobutyl ketone: 75 parts by weight

[0183] [Example 7] As a resin substrate, a polyimide film having a thickness of 80 μm was prepared in the same manner as in Example 4. An optical laminate was produced in the same manner as in Example 4, except that the obtained polyimide film was used.

[0184] [Example 8] A 50 μm thick PET film ("T60" manufactured by Toray Industries, Inc.) was prepared as a resin substrate. The primer layer-forming composition used in Example 1 was applied to one side of the PET film to form a primer layer with a thickness of 0.1 μm. The curable resin composition for a hard coat layer used in Example 1 was applied to the primer layer so that the thickness after curing would be as shown in Table 1, and the applied composition was dried at 70° C. for 1 minute, followed by irradiation with a dose of 200 mJ / cm. 2 The resulting composition was cured by irradiating it with ultraviolet light at a temperature of 100° C. to form a hard coat layer. This resulted in an optical laminate having the resin substrate, the primer layer (intermediate layer), and the hard coat layer in this order.

[0185] [Example 9] A polyethylene naphthalate (PEN) film was prepared as a resin substrate, and a primer layer was formed on one surface of the PEN film in the same manner as in Example 1. Furthermore, a hard coat layer was formed on the primer layer in the same manner as in Example 1. Furthermore, the following curable resin composition for an antireflection layer was applied to the hard coat layer so that the thickness after curing would be 0.1 μm, and the hard coat layer was dried at 70° C. for 1 minute, followed by irradiation with 200 mJ / cm 2 . 2The resulting composition was cured by irradiating it with ultraviolet light at a temperature of 100°C to form an antireflection layer. This resulted in an optical laminate having a resin substrate, a primer layer (intermediate layer), a hard coat layer, and an antireflection layer (LR layer) in this order.

[0186] <Curable resin composition for antireflection layer> Multifunctional acrylate (product name: "KAYARAD PET-30", manufactured by Nippon Kayaku Co., Ltd.): 100 parts by weight Hollow silica (hollow silica particles with an average particle size of 60 nm, surface-treated with a silane coupling agent containing a methacryloyl group): 120 parts by weight (based on 100% solids) ·Photopolymerization initiator (product name: "Omnirad127", IGM Resins BV): 7 parts by mass Silicone leveling agent (product name: "KP-420", manufactured by Shin-Etsu Chemical Co., Ltd.): 10 parts by weight (based on 100% solids) Methyl isobutyl ketone: 6,600 parts by weight Propylene glycol monomethyl ether acetate: 660 parts by mass

[0187] [Comparative Example 1] A 40 μm thick TAC film ("TG40UL" manufactured by Fujifilm Corporation) was prepared as a resin substrate. The curable resin composition for the hard coat layer used in Example 1 was applied to one side of the TAC film so that the thickness after curing would be as shown in Table 1, and the applied film was dried at 70° C. for 1 minute, followed by irradiation with a dose of 200 mJ / cm 2 . 2 The resin was cured by irradiating it with ultraviolet light at a temperature of 100° C. to form a permeation layer and a hard coat layer. This resulted in an optical laminate having the resin substrate, the permeation layer (intermediate layer), and the hard coat layer in this order.

[0188] Comparative Example 2 An optical laminate was produced in the same manner as in Comparative Example 1, except that a TAC film (manufactured by Fujifilm Corporation, "TG60UL") having a thickness of 60 μm was prepared as the resin substrate.

[0189] Comparative Example 3 An optical laminate was produced in the same manner as in Example 4, except that a polyimide film with a thickness of 80 μm was prepared as the resin substrate in the same manner as in Example 4, and the thickness of the penetration layer (intermediate layer) and the thickness of the hard coat layer were changed to the thicknesses shown in Table 1.

[0190] [evaluation] (1) Tensile test The obtained optical laminate was subjected to the above-mentioned tensile test, and the strain A (%) when cracks occurred in the hard coat layer, the strain B (%) when the optical laminate broke, and the tensile modulus C (GPa) of the optical laminate in the strain range of 1% to 2% were determined. Based on these values ​​and the thickness D (μm) of the optical laminate, the X1 value was calculated using the above-mentioned formula (1). The results are shown in Table 1.

[0191] (2) Composite modulus The composite elastic modulus E of the hard coat layer and the composite elastic modulus F of the resin substrate were measured for the obtained optical laminate using the above-mentioned composite elastic modulus measurement method. Based on these values ​​and the thickness G (μm) of the hard coat layer, the X2 value was calculated using the above-mentioned formula (2). The results are shown in Table 1.

[0192] (3) Dynamic bending test The optical laminate obtained was subjected to the dynamic bending test described above to evaluate its bending resistance. The optical laminate was bent so that the surface on the hard coat layer side was facing inward and the surface on the resin substrate side was facing outward. The test involved folding the optical laminate 200,000 times, while reducing the gap in 1.0 mm increments (6 mm → 5 mm → 4 mm → 3 mm → 2 mm), until cracks, breakage, or peeling occurred. The minimum gap (mm) at which cracks, breakage, or peeling did not occur was determined. The results are shown in Table 1 and Figure 8(a).

[0193] (4) Pencil hardness A 100 μm-thick PET film (Toyobo Co., Ltd., "A4160") (composite modulus of elasticity: 6.9 GPa) was bonded to the resin substrate side of the obtained optical laminate via a 50 μm-thick optically transparent adhesive film (OCA) (3M Co., Ltd., "8146-2"; composite modulus of elasticity: 9.6 MPa) to prepare a test laminate. The pencil hardness of the hard coat layer side of the test laminate was measured in accordance with JIS K5600-5-4:1999. A pencil hardness tester (Toyo Seiki Seisakusho Co., Ltd., "Pencil Scratch Coating Hardness Tester (electric type)") was used under the following measurement conditions: angle 45°, load 750 g, speed 1 mm / sec, and temperature 23±2°C. The results are shown in Table 1 and Figure 8(b).

[0194] [Table 1]

[0195] As shown in Table 1, it was confirmed that Examples 1 to 9, in which the X1 value calculated by the above formula (1) was 0.10 or more, had better flex resistance (dynamic flex resistance) than Comparative Examples 1 to 3. It was also confirmed that they had sufficient hardness (2H or more) for a laminate to be placed on the surface of a display device. Furthermore, it was confirmed that Examples 1 to 7 and Example 9, in which the X2 value calculated by the above formula (2) was 10 or more, had even higher pencil hardness than Example 8.

[0196] That is, the present disclosure provides the following inventions.

[0197] [1] A resin substrate; An optical laminate having a hard coat layer disposed on one surface of the resin substrate, An optical laminate in which, when a tensile test is performed on the optical laminate, the X1 value calculated by the following formula (1) is 0.10 or more, where A (%) is the strain when a crack occurs in the hard coat layer, B (%) is the strain when the optical laminate breaks, C (GPa) is the tensile modulus of the optical laminate in a strain range of 1% to 2%, and D (μm) is the thickness of the optical laminate. X1 = (BA) × C / D (1)

[0198] [2] The optical laminate according to [1], wherein the X2 value calculated by the following formula (2) is 10 or more, where E (GPa) is the composite elastic modulus of the hard coat layer, F (GPa) is the composite elastic modulus of the resin substrate, and G (μm) is the thickness of the hard coat layer. X2=E 2 ×F 2 ×G / 1000 (2)

[0199] [3] The optical laminate according to [1] or [2], which has an intermediate layer between the resin substrate and the hard coat layer.

[0200] [4] The optical laminate according to [3], wherein the thickness of the intermediate layer is 0.01 μm or more and 1.0 μm or less.

[0201] [5] The optical laminate according to [3] or [4], wherein the intermediate layer has a refractive index between the refractive index of the resin substrate and the refractive index of the hard coat layer.

[0202] [6] The optical laminate according to any one of [1] to [5], which does not contain fluorine atoms.

[0203] [7] A member for a display device, comprising the optical laminate according to any one of [1] to [6].

[0204] [8] A display panel; A display device comprising: the member for a display device according to [7], which is arranged on the viewer side of the display panel. [Explanation of symbols]

[0205] 1...Resin substrate 2...Hard coat layer 3. Middle class 10... Optical laminate 20... Display device components 30…Display device 31... Display panel

Claims

1. A resin substrate; An optical laminate having a hard coat layer disposed on one surface of the resin substrate, an optical laminate in which, when a tensile test is performed on the optical laminate, the X1 value calculated by the following formula (1) is 0.10 or more, where A (%) is the strain when a crack occurs in the hard coat layer, B (%) is the strain when the optical laminate breaks, C (GPa) is the tensile modulus of the optical laminate in a strain range of 1% to 2%, and D (μm) is the thickness of the optical laminate: X1=(B-A)×C / D (1)

2. 2. The optical laminate according to claim 1, wherein the X2 value calculated by the following formula (2) is 10 or more, where E (GPa) is the composite elastic modulus of the hard coat layer, F (GPa) is the composite elastic modulus of the resin substrate, and G (μm) is the thickness of the hard coat layer. X2=E ２ ×F ２ ×G / 1000 (2)

3. The optical laminate according to claim 1 , further comprising an intermediate layer between the resin substrate and the hard coat layer.

4. The optical laminate according to claim 3 , wherein the thickness of the intermediate layer is 0.01 μm or more and 1.0 μm or less.

5. The optical laminate according to claim 3 , wherein the intermediate layer has a refractive index between the refractive index of the resin substrate and the refractive index of the hard coat layer.

6. The optical laminate according to claim 1 , wherein the optical laminate does not contain fluorine atoms.

7. A member for a display device, comprising the optical laminate according to any one of claims 1 to 6.

8. A display panel; A display device comprising: the member for a display device according to claim 7 , which is disposed on a viewer's side of the display panel.

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