Optical laminate, member for display device, and display device

Abstract

The present disclosure provides an optical laminate having a resin base material and a hard coat layer disposed on one surface of the resin base material, wherein, when a tensile test is performed on the optical laminate, the value X1 calculated by 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 is broken, C (GPa) is the tensile elastic modulus in a section in which the strain of the optical laminate is 1% to 2%, and D (µm) is the thickness of the optical laminate. (1): X1 = (B - A) × C / D

Description

Optical laminate, member for display device, and display device

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

[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.

[0005] JP 2014-238614 A JP 2014-186210 A

[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.

[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 greater, where A (%) denotes the strain at which a crack occurs in the hard coat layer, B (%) denotes the strain at which 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=(B−A)×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.

[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.

[0011] FIG. 1 is a schematic cross-sectional view illustrating an example of an optical laminate according to the present disclosure. FIG. 2 is a schematic cross-sectional view illustrating an example of an optical laminate according to the present disclosure. FIG. 3 is a schematic view illustrating a method for preparing a sample for a tensile test. FIG. 4 is a schematic view illustrating a tensile test. FIG. 5 is a schematic view illustrating a dynamic bending test. FIG. 6 is a schematic cross-sectional view illustrating an example of a member for a display device according to the present disclosure. FIG. 7 is a schematic cross-sectional view illustrating an example of a display device according to the present disclosure. FIG. 8 is a schematic view illustrating the results of a dynamic bending test and a pencil hardness test for examples and comparative examples. FIG. 9 is a schematic view illustrating the elongation of the optical laminate according to the present disclosure when bent.

[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 of 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 greater, 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=(B−A)×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), (B-A) 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 hard coat layer, which has higher rigidity and is thinner, breaks first, causing cracks to occur in the hard coat layer. Subsequently, the resin substrate also breaks from the crack in the hard coat layer, causing the entire optical laminate to break. A large (B-A) 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 (B-A) means that when 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 is designed not to decrease, that is, by increasing (B-A), 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 (B-A).

[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, and bending resistance is good.

[0020] 9 is a schematic diagram showing the elongation of the neutral plane NS and outer surface S1 of the bent portion (10R in FIG. 5) of an optical laminate having 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 interval d in FIG. 5 is 3 mm). When the neutral plane NS is located at the center of the thickness of the optical laminate, 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 by (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 adopted as 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 until the optical laminate breaks in a tensile test, the influence of a predetermined tensile modulus of the optical laminate and 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 X1 value 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 (%) 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 the strain range of 1% to 2%, and D (μm) denotes the thickness of the optical laminate. X1 = (B - A) × 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, (B-A) becomes relatively small, the tensile modulus 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, flex resistance and surface hardness are improved.

[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 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 the tensile test, the tensile modulus C in the strain range of the optical laminate from 1% to 2%, and the thickness D of the optical laminate.

[0028] In the above formula (1), (B-A) is, for example, 1.5% or more, preferably 2.0% or more, and more preferably 2.5% or more. By having (B-A) in the above range, surface hardness and flex resistance can be improved. On the other hand, (B-A) is, for example, 30.0% or less, preferably 25.0% or less, and more preferably 20.0% or less. (B-A) 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 (B-A) include a method for adjusting the thickness of an intermediate layer, which will be described later, and a method for selecting the type of intermediate layer. For example, by disposing a primer layer as an intermediate layer, (B-A) can be increased. For example, by disposing a permeation layer of a predetermined thickness as an intermediate layer, (B-A) can be increased.

[0030] Other means for adjusting (B-A) 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 range of the X1 value, 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 bending 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 in the above-mentioned range, the bending resistance can be improved. 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 in the above-mentioned range, the impact resistance and the surface hardness of the surface on the hard coat layer side of the optical laminate can be increased. 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 in the strain range of 1% to 2% of the optical laminate can be determined by performing the following tensile test on the optical laminate. Fig. 3 is a schematic diagram illustrating a method for preparing a sample for the tensile test. Fig. 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 size of 100 mm x 10 mm to obtain a sample S. Step 2) As shown in FIG. 3(b), three sheets of cellophane tape T manufactured by Nichiban Co., Ltd. are stacked and cut into a size of 30 mm x 5 mm. Two of these cut pieces of tape 41 are prepared. Step 3) As shown in FIGS. 3(c) and 3(d), the two cut pieces of tape 41 are attached to the optical laminate sample S so that they are spaced 50 mm apart, and folded back to form a handle. Step 4) As shown in FIG. 4(a), the handle portion is chucked and adjusted so that the tensile load is 1 N. Step 5) A tensile test is started using a tensile tester under the following measurement conditions. The tensile tester used is an "AUTOGRAPH AG-X" manufactured by Shimadzu Corporation. Step 6) As shown in Figure 4(b), the test area is illuminated with an LED light and observed, and the distance La (mm) when a crack appears in the hard coat layer of the sample is recorded, and strain A is calculated using the following formula: Strain A = ((La - 50) / 50) x 100(%) Step 7) As shown in Figure 4(c), the distance Lb (mm) when the entire sample breaks is recorded, and strain B is calculated using the following formula: Strain B = ((Lb - 50) / 50) x 100(%) Step 8) On the stress-strain curve, the slope corresponding to the two points of the stress at 1% strain and the stress at 2% strain is taken as the tensile modulus C.

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

[0038] 2. X2 Value Calculated by Formula (2) In the optical laminate according to 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 10 or more, more preferably 15 or more, and even more preferably 20 or more. On the other hand, the X2 value is, for example, 80 or less, preferably 75 or less, and more preferably 70 or less. 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, and scratch resistance can be improved. 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) is measured on a measurement sample using a "TI950 TriboIndenter" manufactured by BRUKER. Specifically, first, a block is prepared by embedding an optical laminate cut into a size of 1 mm x 10 mm in an embedding resin, and a uniform slice having a thickness of 50 nm to 100 nm is cut from this block using a general slice preparation method. An "Ultramicrotome EM UC7" (manufactured by Leica Microsystems) or the like can be used to prepare the slice. The remaining block from which the uniform slice without holes is cut serves as the measurement sample. Next, in the cross section obtained by cutting out the slice of such a measurement sample, a Berkovich indenter (triangular pyramid, TI-0039 manufactured by BRUKER) is pressed vertically into the center of the cross section of the hard coat layer over 10 seconds under the following measurement conditions up to a maximum load of 25 μN. 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 at a distance of 500 nm 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 at a distance of 500 nm from each of both side edges 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 ＩＴ The above contact projected area is a contact projected area corrected for the curvature of the indenter tip by the Oliver-Pharr method using a standard sample of fused quartz (5-0098 manufactured by BRUKER). 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 (a-b) / b x 100, where a is the measured value and b is the arithmetic mean value, is more than ±20%.

[0044] <Measurement conditions 1> ・Loading speed: 2.5 μN / sec ・Holding time: 5 seconds ・Load unloading rate: 2.5 μN / sec ・Measurement temperature: 25°C

[0045] When measuring the 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 the 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 conditions 2> ・Loading speed: 0.5μN / sec ・Holding time: 5 seconds ・Loading unloading rate: 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 is calculated by measuring the indentation hardness at 10 points and calculating the composite elastic modulus E each time. ｒ The composite elastic modulus E ｒ The arithmetic mean value of

[0048] (In the above formula (1), A ｐ is the contact projection area, and E ｒ is the composite elastic modulus of the hard coat layer, and S is the contact stiffness.

[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, and scratch resistance can be improved. 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 large, the hardness becomes too high and it becomes difficult to bend, which may result in 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 average of the thicknesses of any 10 locations obtained by measuring a cross section of the optical laminate in the thickness direction observed with a scanning electron microscope (SEM). A specific method for taking a cross-sectional photograph is described below. First, the optical laminate is cut into a size of 2 cm x 2 cm, and a block is prepared by embedding the optical laminate in an embedding resin, and a cross section is prepared using a polishing machine. As the polishing machine, a TegraPol-35 manufactured by Struers can be used. Then, a cross-sectional photograph of the measurement sample is taken using a scanning electron microscope. As the scanning electron microscope, an S-4800 manufactured by Hitachi High-Technologies Corporation can be used. When taking a cross-sectional photograph using a scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation), the cross section is observed by setting the detector to "Lower," the acceleration 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, while 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 WD 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 ​​are then calculated for the cross-sectional photographs at both magnifications, and these mean values ​​are used to determine the thickness of each layer. If the interface is difficult to discern, it may be possible to make the interface visible 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 Figures 1 and 2 are schematic cross-sectional views showing an example of an optical laminate in the present disclosure. As shown in Figures 1 and 2, the optical laminate 10 has a resin substrate 1 and a hard coat layer 2. Furthermore, as shown in Figures 2(a) and 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) Material of Resin Substrate 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 co-extruded 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 increased.

[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 surface hardness. By providing the hard coat layer, scratch resistance can be improved.

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

[0064] The pencil hardness of the surface of 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) Structure of Hard Coat Layer 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) Material for Hard Coat Layer Examples of the material for the hard coat layer include a cured resin. 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. As the polymerizable compound, for example, at least one of a radical polymerizable compound and a cation polymerizable compound can be used.

[0069] A radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of a 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 a 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] As the radical polymerizable compound, from the viewpoint of high reactivity, compounds having a (meth)acryloyl group are preferred. 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, can be preferably used. Polyfunctional (meth)acrylate polymers having two or more (meth)acryloyl groups in the side chain of the acrylate polymer can also be preferably used. Among these, polyfunctional (meth)acrylate monomers having two or more (meth)acryloyl groups in one molecule can be 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 be further improved. In addition, a polyfunctional (meth)acrylate oligomer or polymer having two or more (meth)acryloyl groups in one molecule can also 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 obtained by modifying these with PO, EO, or caprolactone is preferred.

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

[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 an epoxy group and an oxetanyl group are preferred because they cause little shrinkage during the polymerization reaction. Among cyclic ether groups, compounds having an epoxy group are readily available in a variety of structures, have no adverse effect on 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, an oxetanyl group has a higher degree of polymerization and lower toxicity than an epoxy group, and has the advantage of accelerating the network formation rate obtained from the cationically polymerizable compound in the coating film when the resulting hard coat layer is combined with a compound having an epoxy group, thereby forming an independent network without leaving unreacted monomers in the film even in regions where the radically polymerizable compound is mixed.

[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 homopolymers and copolymers of glycidyl (meth)acrylate; glycidyl ethers produced by reacting bisphenols such as bisphenol A, bisphenol F, and hydrogenated bisphenol A, or derivatives thereof such as alkylene oxide adducts or caprolactone adducts, with epichlorohydrin; and glycidyl ether-type epoxy resins derived from bisphenols, such as 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, for example, JP 2018-104682 A. 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 the decomposition product 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. When the hard coat layer contains particles, the hardness can be improved.

[0083] Examples of inorganic particles include silica (SiO ２Examples of the particles include metal oxide particles such as 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, as excellent hardness can be obtained.

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

[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 surfaces 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 particles 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 become 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) UV absorber The hard coat layer may contain a UV absorber. This can suppress UV-induced deterioration of the resin substrate. In addition, in a display device including the optical laminate, this can suppress UV-induced deterioration of components arranged on the display panel side of the optical laminate, such as polarizers.

[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 due to 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 these, 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 used in combination.

[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, excellent scratch resistance can be imparted 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 parts by mass or more and 3.0 parts by mass or less relative to 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, and if the content of the antifouling agent is too high, the hardness of the hard coat layer may be reduced.

[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 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 includes, for example, a method of applying a curable resin composition for hard coat layer containing the polymerizable compound, etc. to one surface of the resin substrate, and curing the composition. The curable resin composition for 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. or higher and 120° C. or lower for 10 seconds or longer and 180 seconds or shorter.

[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 light rays of an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, etc. can be used. The irradiation amount of the energy ray source is, for example, 50 mJ / cm as the cumulative exposure amount 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 may be performed by leaving the mixture at room temperature (25°C) for 24 hours or longer. 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 may be performed by leaving the mixture at room temperature (25°C) for 24 hours or longer.

[0114] (3) Intermediate Layer 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 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, (B-A) in the above formula (1) tends to be large, and the X1 value is 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 according to 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 enhance 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 penetration layer as an intermediate layer. The penetration layer 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 is a layer containing the components constituting the resin substrate and the components constituting the hard coat layer. Therefore, the penetration layer enhances the integrity of the resin substrate and the hard coat layer. Furthermore, since the penetration 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, so that cracks in the hard coat layer will more likely affect the breakage of the entire optical laminate. Therefore, (B-A) in the above formula (1) tends to be small. 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 (B-A) in the above formula (1) tends to be large, and the X1 value is likely to be within the above range.

[0128] (4) Antireflection Layer As shown in Fig. 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 strain 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 can be ignored.

[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. On the other hand, 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 anti-reflection layer can be a general anti-reflection layer. Examples of the anti-reflection 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 (anti-reflection), 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 any material having a refractive index lower than that of the hard coat layer. Examples of such low refractive index layers include those containing low refractive index particles, those containing low refractive index resins, those containing binder resins and low refractive index particles, and those containing hydrolysis polycondensates of metal alkoxides. Among these, it is preferable that the low refractive index layer contains binder resins 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. Therefore, it is possible to suppress a decrease in the transparency of the low refractive index layer due to particle size increase caused by 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 or more and 200 nm or less, more preferably 10 nm or more and 150 nm or less. Furthermore, when the low refractive index particles are hollow particles, the average particle diameter is, for example, preferably 5 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, and even more preferably 50 nm or more and 110 nm or less. 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 sufficiently. 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 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 using 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, for example, 50,000 to 300,000. (2) Ten particles are randomly selected from the observed image, and the particle size of each particle is calculated. The particle size is measured as the distance between two parallel lines that maximize the distance between the two lines when the cross section of the particle is sandwiched between the two lines. (3) The same procedure is performed five times using a separate image of the same sample, and the value obtained from the number average of a total of 50 particles is used as the average particle size of the particles.

[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 or more and 250 parts by mass or less, more preferably 30 parts by mass or more and 230 parts by mass or less, and even more preferably 40 parts by mass or more and 200 parts by mass or less, relative to 100 parts by mass of the binder resin of the low refractive index layer. When 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. Properties of the Optical Laminate (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. When the Young's modulus is within the above range, the surface hardness and bending resistance can be improved. 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 for an optical laminate with 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 in 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 for an optical laminate with 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) Bending Resistance The optical laminate according to the present disclosure preferably has bending resistance. Specifically, when the optical laminate according to the present disclosure is subjected to a dynamic bending 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 x 100 mm is prepared. Next, as shown in FIG. 5( a), the short side portion 10P of the optical laminate 10 and the short side portion 10Q opposite the short side portion 10P are fixed by parallel-arranged fixing portions 100A and 100B, respectively. At this time, the optical laminate is fixed so that the surface of the hard coat layer side faces inward when bent. As shown in FIG. 5( a), the fixing portions 100A and 100B are slidable horizontally. Next, as shown in FIGS. 5( b) and 5( c), the fixing portions 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 side portions 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 distance d is reduced in 1 mm increments (6 mm → 5 mm → 4 mm → 3 mm → 2 mm), and the optical laminate is folded 200,000 times until cracks, breaks, or peeling occurs. The minimum distance at which cracks, breaks, and peeling do not occur in the optical laminate is recorded. For example, if cracks occur when the distance d is 3 mm, the minimum distance at which cracks, breaks, and peeling do not occur is 4 mm.

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

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

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

[0153] B. Member for display device The present disclosure provides a member for a display device having the above-described optical laminate. Figure 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. First Functional Layer The first functional layer may be a single layer or may have multiple layers. The first functional layer may have a single function or may have multiple layers with 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. Uses A member for a display device according to the present disclosure can be used as a member arranged on the viewer side of a 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.

[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 Seisaku-sho, 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] <Composition for primer layer> Amorphous polyester (product name "Vylon 63SS", manufactured by Toyobo Co., Ltd.): 3.85 parts by mass (value converted to 100% solids) Zirconium oxide (average particle size 20 nm, manufactured by CIK Nanotech Co., Ltd.): 1.15 parts by mass (value converted to 100% solids) Methyl isobutyl ketone: 95 parts by mass The above "value converted to 100% solids" 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. After that, the applied composition was exposed to an irradiation 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.

[0171] <Curable resin composition for hard coat layer> Urethane acrylate (product name "UV-7600B", manufactured by Mitsubishi Chemical Corporation): 100 parts by mass (based on 100% solids content) Reactive silica (product name "MIBK-SD", manufactured by Nissan Chemical Industries, Ltd.): 50 parts by mass (based on 100% solids content) Photopolymerization initiator (product name "Omnirad 184", manufactured by IGM Resins B.V.): 4 parts by mass Leveling agent (product name "BYK-UV 3500", manufactured by BYK Japan KK): 0.2 parts by mass Methyl ethyl ketone: 225 parts by mass

[0172] Examples 2 and 3 Optical laminates were 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]

[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 solution temperature was controlled to 30°C. 24.8 g (40.1 mmol) of tetracarboxylic acid dianhydride (TMPBPTME) represented by the above formula was gradually added so that the temperature did not rise more than 2°C, and the mixture was stirred with a mechanical stirrer for 3 hours. Subsequently, 0.91 g (4.5 mmol) of terephthalic acid dichloride (TPC) was added to the solution, and the mixture was stirred for an additional 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, and the mixture was stirred at 25°C for 30 minutes to confirm that the solution was homogeneous. The mixture was then heated to 70°C and stirred for 1 hour. After that, 174.26 g of 2-propyl alcohol (IPA) was gradually added to the solution cooled to room temperature, resulting in a slightly cloudy solution. 435.64 g of IPA was added all at once to the cloudy solution to obtain a white slurry. The slurry was filtered and washed five times with IPA, and then dried for six hours under reduced pressure in an oven heated to 100°C 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 the polyamideimide to prepare a polyamideimide varnish containing 19% by weight of polyamideimide in the varnish, and the viscosity of the polyamideimide varnish (solids concentration 19% by weight) 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 circulating oven described below would be 50 μm. The plate was then dried in a circulating oven at 120° C. for 10 minutes, cooled to 25° C., and the polyimide resin coating film was peeled off.

[0178] The peeled polyimide-based resin coating film was cut into a size of 150 mm x 200 mm. The cut polyimide-based resin coating film 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 the polyimide-based resin coating film were fixed with a fixture. The fixed polyimide-based resin coating film was heated to 300°C at a heating rate of 10°C / min in a circulating oven under a nitrogen stream (oxygen concentration of 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. After that, the applied film was exposed to an irradiation dose of 200 mJ / cm. ２ The resin substrate 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 penetration 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 mass (value calculated as 100% solids) Photopolymerization initiator (product name "Omnirad 184", manufactured by IGM Resins B.V.): 4 parts by mass Silicone leveling agent (product name "BYK-UV 3500", manufactured by BYK Japan): 0.2 parts by mass Methyl ethyl ketone: 75 parts by mass Methyl isobutyl ketone: 75 parts by mass

[0183] [Example 7] A polyimide film having a thickness of 80 μm was prepared as a resin substrate 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 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 in the same manner as in Example 1, and a primer layer was formed on one surface of the PEN film. 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 was 0.1 μm, and the hard coat layer was dried at 70° C. for 1 minute, followed by irradiation with 200 mJ / cm. ２ The resulting composition was cured by irradiating it with ultraviolet light at a temperature of 1000 K. 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> Polyfunctional acrylate (product name: "KAYARAD PET-30", manufactured by Nippon Kayaku Co., Ltd.): 100 parts by mass Hollow silica (hollow silica particles having an average particle size of 60 nm, surface-treated with a silane coupling agent having a methacryloyl group): 120 parts by mass (based on 100% solids content) Photopolymerization initiator (product name: "Omnirad 127", manufactured by IGM Resins B.V.): 7 parts by mass Silicone leveling agent (product name: "KP-420", manufactured by Shin-Etsu Chemical Co., Ltd.): 10 parts by mass (based on 100% solids content) Methyl isobutyl ketone: 6,600 parts by mass 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 The resin substrate 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 having a thickness of 80 μm was prepared as the resin substrate in the same manner as in Example 4, and the thicknesses of the penetration layer (intermediate layer) and the hard coat layer were changed to those shown in Table 1.

[0190] [Evaluation] (1) Tensile Test The above-mentioned tensile test was performed on the obtained optical laminate, and the strain A (%) when a crack 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 Elastic 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 by 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 by the above-mentioned formula (2). The results are shown in Table 1.

[0192] (3) Dynamic Bending Test The above-described dynamic bending test was performed on the obtained optical laminate to evaluate the bending resistance of the optical laminate. In this test, the optical laminate was bent so that the surface on the hard coat layer side was on the inside and the surface on the resin substrate side was on the outside. The test was repeated by 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 FIG. 8(a).

[0193] (4) Pencil Hardness A 100 μm thick PET film ("A4160" manufactured by Toyobo Co., Ltd., composite modulus 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) ("8146-2" manufactured by 3M Corporation, composite modulus 9.6 MPa) to prepare a test laminate. The pencil hardness of the surface of the hard coat layer side of the test laminate was measured. In this case, the pencil hardness was measured in accordance with JIS K5600-5-4:1999. A pencil hardness tester ("Pencil Scratch Coating Hardness Tester (electric type)" manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used, and the measurement conditions were an angle of 45°, a load of 750 g, a speed of 1 mm / sec, and a temperature of 23±2°C. The results are shown in Table 1 and FIG. 8(b).

[0194]

[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 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] 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=(B−A)×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], wherein the optical laminate 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 device comprising: a display panel; and the member for a display device according to [7], which is arranged on the viewer side of the display panel.

[0205] REFERENCE SIGNS LIST 1... resin substrate 2... hard coat layer 3... intermediate layer 10... optical laminate 20... member for display device 30... display device 31... display panel

Claims

1. 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 elasticity of the optical laminate in the strain range of 1% to 2%, and D (μm) is the thickness of the optical laminate: X1=(B-A)×C / D (1) 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, which has 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 device comprising: a display panel; and the member for a display device according to claim 7, arranged on the viewer side of the display panel.

Images