Stacked body for display device and display device

Abstract

The present disclosure provides a laminate for display device sequentially having a substrate layer, a first layer, and a second layer, wherein, when light is incident to a surface of the second layer side of the laminate for display device at an incident angle of 60°, the apparent reflectance of regular reflection light is 10.0% or less, and the absolute value of the difference between the yellow index YI1 of the transmitted light in the direction of 60° with respect to the normal line of the surface of the second layer side of the laminate for display device and the yellow index YI2 of the transmitted light in the direction of 15° with respect to the normal line of the surface of the second layer side of the laminate for display device is 3.0 or less.

Description

Laminates for display devices and display devices Technical Field

[0001] This disclosure relates to a laminate for a display device and a display device using the laminate. Background Technology

[0002] The surface of the display device is provided with a laminate containing functional layers that have various properties such as hard coating, scratch resistance, anti-reflection, anti-glare, antistatic and anti-fouling properties.

[0003] Recently, flexible displays such as foldable displays, rollable displays, and bendable displays have attracted much attention, and efforts have been made to develop laminates that can be configured on the surface of flexible displays.

[0004] For flexible displays, it is required that there will be no display defects even if they are repeatedly bent, and that they have bend resistance.

[0005] In flexible displays, there is a usage mode where images are viewed, for example, in a bent state. For example, Figure 3 is a schematic cross-sectional view illustrating a usage mode of a foldable display. As illustrated in Figure 3, in a usage mode where images are viewed with the foldable display 20 bent, the foldable display 20 has a first display area 22 and a second display area 23 bounded by the bend 21. In this case, the following problem arises: images or text displayed in the second display area 23 are projected onto the first display area 22, or images or text displayed in the first display area 22 are projected onto the second display area 23, reducing the visibility of the images or text. This problem is not limited to foldable displays; the same issue arises when images are viewed in a bent state in flexible displays.

[0006] Furthermore, in display devices, the color tone of the image changes depending on the viewing direction. Additionally, as illustrated in Figure 3, in a usage configuration where the image is viewed with the foldable display screen 20 bent, the observer 25 tends to observe the images displayed in the first display area 22 and the second display area 23 by moving only their line of sight without changing their viewing position. In this usage configuration, as illustrated in Figure 3, since the observer 25's position is fixed, the angle of the viewing direction relative to the normal to the surface of the foldable display screen 20 on the observer 25 side differs in the first display area 22 and the second display area 23. Therefore, there is a problem where the image color tone differs in the first display area 22 and the second display area 23. This is not limited to foldable displays; the same problem occurs in flexible displays when the image is viewed in a bent state.

[0007] As a means to improve the visibility of flexible displays, for example, Patent Document 1 proposes a hard coating to solve the problem of reduced visibility caused by interference fringes due to hard coating. The hard coating comprises a substrate film and a hard coating layer deposited on at least one main surface side of the substrate film. The substrate film is a polyimide film, the difference between the refractive index of the polyimide film and the refractive index of the hard coating layer is 0.04 or less in absolute value, the thickness of the polyimide film is 5 μm or more and 50 μm or less, and the thickness of the hard coating layer is 0.5 μm or more and 10 μm or less.

[0008] Furthermore, for example, in Patent Document 2, in order to solve the problem that the visually discernible hue changes depending on the viewing angle in a display device equipped with an anti-reflective film, an anti-reflective film is proposed. This anti-reflective film has a transparent substrate film and an anti-reflective layer formed on at least one of the transparent substrate film. The anti-reflective film has a visual sensitivity reflectance of 0.6% or less related to orthogonal reflection at an incident angle of 5°, a difference between the maximum and minimum values ​​of the reflectance (%) related to orthogonal reflection at an incident angle of 5° in the wavelength range of 450nm to 750nm is 0.75 or less, and a difference between the maximum and minimum values ​​of the reflectance (%) related to orthogonal reflection at an incident angle of 45° in the wavelength range of 400nm to 700nm is 1.5 or less.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2018-109773

[0012] Patent Document 2: Japanese Patent Application Publication No. 2019-70756 Summary of the Invention

[0013] The technical problem that the invention aims to solve

[0014] However, in Patent Documents 1 and 2, the visibility of images in a usage mode where the display device is bent was not studied, and in reality, no laminate capable of improving visibility in such a usage mode has been proposed.

[0015] Furthermore, there is room for improvement in the visibility of images or text in the curved sections of flexible displays.

[0016] The first embodiment in this disclosure was made in view of the above-mentioned actual situation, and its main objective is to provide a laminate for a display device that can improve the visibility of an image in a usage mode in which the display device is bent.

[0017] Furthermore, the second embodiment in this disclosure was made in view of the above-mentioned actual situation, and its main purpose is to provide a laminate for a display device that can improve the visibility of images or text in the curved portion and improve the visibility in the usage mode of observing images in the bent state of the display device.

[0018] means of solving technical problems

[0019] The first embodiment of this disclosure provides a laminate for a display device, which is a laminate for a display device having a substrate layer, a first layer, and a second layer in sequence, wherein when light is incident on the surface of the laminate for a display device at an incident angle of 60° on the second layer side, the visual reflectivity of the orthogonal reflected light is 10.0% or less.

[0020] The absolute value of the difference between the yellowness YI1 of the transmitted light in a direction with a normal of 60° relative to the surface of the second layer of the laminate for the display device and the yellowness YI2 of the transmitted light in a direction with a normal of 15° relative to the surface of the second layer of the laminate for the display device is 3.0 or less.

[0021] In the laminated body for the display device in this manner, the thickness of the second layer is preferably 1 μm or more and 10 μm or less, and the refractive index of the second layer is 1.40 or more and 1.50 or less.

[0022] In the laminated display device of this method, the thickness of the second layer is preferably 50 nm or more and 1 μm or less, and the ratio of the refractive index of the first layer to the refractive index of the second layer is 1.05 or more and 1.20 or less.

[0023] Furthermore, in the laminated display device of this method, the substrate layer can also serve as the first layer.

[0024] In addition, in the laminate for display devices in this manner, a hard coating layer may be present between the substrate layer and the first layer.

[0025] In addition, in the laminated display device of this method, an impact-absorbing layer may be provided on the side of the substrate layer opposite to the first layer, or between the substrate layer and the first layer.

[0026] In addition, in the laminate for display devices in this manner, an adhesive layer for attachment may be provided on the side of the substrate layer opposite to the first layer.

[0027] Another embodiment of this approach provides a display device having a display panel and a display device laminate disposed on the observer side of the display panel.

[0028] The second embodiment of this disclosure provides a laminate for a display device, which is a laminate for a display device having a substrate layer and a functional layer. When light is incident on the surface of the laminate for the display device at an incident angle of 60° on the functional layer side, the perceived reflectivity of the positively reflected light is 10.0% or less. After surface modification of the surface of the laminate for the display device with respect to the functional layer side, in a steel wool test where the surface of the laminate for the display device with the functional layer side is subjected to a predetermined load of 100 cycles of reciprocating friction using #0000 steel wool, the maximum load without peeling of the functional layer is 1.0 kg / cm². 2 Above 2.0kg / cm 2 the following.

[0029] In this method, the functional layer in the laminated display device is preferably an inorganic film.

[0030] In the above cases, it is preferable that the inorganic membrane contains silicon dioxide.

[0031] Furthermore, in the laminated display device of this method, the thickness of the aforementioned functional layer is preferably 50 nm or more and 140 nm or less.

[0032] Furthermore, in the laminated display device of this method, the refractive index of the aforementioned functional layer is preferably 1.40 or higher and 1.50 or lower.

[0033] In the laminated display device of this method, a second functional layer may be provided between the substrate layer and the functional layer. In this case, it is preferable that the second functional layer contains resin and inorganic particles.

[0034] In the above case, the thickness of the second functional layer is preferably 50 nm or more and 10 μm or less.

[0035] In addition, under the above circumstances, the refractive index of the second functional layer is preferably 1.55 or higher and 2.00 or lower.

[0036] In addition, in the laminated display device of this method, a hard coating layer may be provided between the substrate layer and the functional layer.

[0037] In addition, in the laminated display device of this method, an impact-absorbing layer may be provided on the side of the substrate layer opposite to the functional layer.

[0038] In addition, in the laminated display device of this method, an adhesive layer for attachment may be provided on the side of the substrate layer opposite to the functional layer.

[0039] Another embodiment of this approach provides a display device having a display panel and a display device laminate disposed on the observer side of the display panel.

[0040] The effects of the invention

[0041] The first embodiment of this disclosure provides a display device laminate that can improve visibility in a usage mode where the image can be viewed in a bent state.

[0042] Furthermore, the second embodiment of this disclosure provides a display device laminate that can improve the visibility of images or text in the bent portion and improve the visibility in a usage mode where the image is observed while the display device is bent. Attached Figure Description

[0043] Figure 1 is a schematic cross-sectional view illustrating the laminate for the display device in the first embodiment.

[0044] Figure 2 is a schematic cross-sectional view illustrating the laminate for the display device in the first embodiment.

[0045] Figure 3 is a schematic cross-sectional view illustrating the foldable display screen in the first embodiment.

[0046] Figure 4 is a schematic diagram illustrating the dynamic bending test.

[0047] Figure 5 is a schematic cross-sectional view illustrating the laminate for the display device in the first embodiment.

[0048] Figure 6 is a schematic cross-sectional view illustrating the laminate for the display device in the first embodiment.

[0049] Figure 7 is a schematic cross-sectional view illustrating the laminate for the display device in the first embodiment.

[0050] Figure 8 is a schematic cross-sectional view illustrating the laminate for the display device in the first embodiment.

[0051] Figure 9 is a schematic cross-sectional view illustrating the display device in the first embodiment.

[0052] Figure 10 is a schematic cross-sectional view illustrating the laminate for the display device in the second embodiment.

[0053] Figure 11 is a schematic cross-sectional view illustrating the laminate for the display device in the second embodiment.

[0054] Figure 12 is a schematic cross-sectional view illustrating the foldable display screen in the second embodiment.

[0055] Figure 13 is a schematic cross-sectional view illustrating the laminate for the display device in the second embodiment.

[0056] Figure 14 is a schematic cross-sectional view illustrating the laminate for the display device in the second embodiment.

[0057] Figure 15 is a schematic cross-sectional view illustrating the laminate for the display device in the second embodiment.

[0058] Figure 16 is a schematic cross-sectional view illustrating the laminate for the display device in the second embodiment.

[0059] Figure 17 is a schematic cross-sectional view illustrating the laminate for the display device in the second embodiment.

[0060] Figure 18 is a schematic cross-sectional view illustrating the display device in the second embodiment. Detailed Implementation

[0061] The embodiments of this disclosure will now be described with reference to the accompanying drawings. However, this disclosure can be implemented in many different ways and is not to be construed as limited to the embodiments illustrated below. Furthermore, for the purpose of clearer explanation, the drawings sometimes schematically represent the width, thickness, shape, etc., of various parts compared to the actual embodiments; however, these are always examples and are not intended to limit the interpretation of this disclosure. Additionally, in this specification and the drawings, elements identical to those described in the previously shown drawings are given the same reference numerals, and detailed descriptions are sometimes appropriately omitted.

[0062] In this specification, when describing the arrangement of other components above a component, the use of only "above" or "below" includes, unless otherwise specified, both the case where the other component is arranged directly above or below a component in a manner that contacts the component, and the case where the other component is arranged above or below a component, further separated by another component. Similarly, in this specification, when describing the arrangement of other components on the surface of a component, the use of only "surface side" or "surface" includes, unless otherwise specified, both the case where the other component is arranged directly above or below a component in a manner that contacts the component, and the case where the other component is arranged above or below a component, further separated by another component.

[0063] The following description of the display device laminate and the display device in this disclosure is divided into a first embodiment and a second embodiment.

[0064] I. First Implementation

[0065] First, the display device laminate and the display device of the first embodiment will be described.

[0066] A. Laminated substrate for display devices

[0067] The display device laminate in this embodiment is a display device laminate having a substrate layer, a first layer, and a second layer in sequence. When light is incident on the surface of the second layer side of the display device laminate at an incident angle of 60°, the visual reflectivity of the positively reflected light is 10.0% or less, and the absolute value of the difference between the yellowness YI1 of the transmitted light in the direction with a normal of 60° relative to the surface of the second layer side of the display device laminate and the yellowness YI2 of the transmitted light in the direction with a normal of 15° relative to the surface of the second layer side of the display device laminate is 3.0 or less.

[0068] Figure 1 is a schematic cross-sectional view showing an example of a laminate for a display device according to this embodiment. As shown in Figure 1, the laminate for a display device 1 sequentially includes a substrate layer 2, a first layer 3, and a second layer 4. Furthermore, as illustrated in Figure 2(a), when light is incident at an angle of 60° onto the surface S1 of the second layer side of the laminate for a display device 1, the perceived reflectivity of the positively reflected light L1 is below a predetermined value. Additionally, as illustrated in Figure 2(a), the difference between the yellowness YI1 of the transmitted light L2 at a direction normal to the surface S1 of the second layer side of the laminate for a display device 1 at 60° and the yellowness YI2 of the transmitted light L3 at a direction normal to the surface S1 of the second layer side of the laminate for a display device 1 is below a predetermined value.

[0069] Here, for example, in a foldable display screen, we assume a usage configuration where the image is viewed in a bent state. In such a configuration, as shown in FIG3, the foldable display screen 20 has a first display area 22 and a second display area 23 bounded by the bend 21. In this case, if the image or text displayed in the second display area 23 is projected onto the first display area 22, or vice versa, the visibility of the image or text is reduced. This is not limited to foldable displays; the same problem arises in flexible displays when the image is viewed in a bent state.

[0070] In contrast, in this embodiment, when light is incident at an angle of 60° onto the surface S1 of the second layer side of the laminate 1 for display device, the apparent reflectivity of the positively reflected light L1 is below a predetermined value. As a result, when the laminate for display device is used in a flexible display screen, when the image is viewed in a bent state of the flexible display screen, it is possible to suppress the image or text displayed in one display area from being reflected into another display area.

[0071] For example, in a foldable display screen, when viewing an image in a bent state, the angle θ2 between the first display area 22 and the second display area 23, as illustrated in FIG3, is tended to be set to a value greater than 90° and less than 180° from the perspective of the visibility of the displayed image or text; specifically, for example, it is set to around 120°. When a display device laminate is arranged on the observer 25 side of such a foldable display screen 20, as shown in FIG2(b), the display device laminate 1 has a first area 12 and a second area 13 bounded by the bend 11, and the angle θ1 between the first area 12 and the second area 13 is the same as the aforementioned angle θ2.

[0072] For example, in Figure 2(b), when light is incident at an angle of 60° onto the surface S1 of the second layer of the laminate 1 for the display device, if the apparent reflectivity of the positively reflected light L1 is below a predetermined value, then in the foldable display screen 20 illustrated in Figure 3, it is possible to suppress the reflection of light from the second display area 23 corresponding to the second region 13 of the laminate 1 for the display device by the first display area 22 corresponding to the first region 12 of the laminate 1 for the display device. Therefore, when the laminate for the display device of this embodiment is used in a flexible display screen, when observing an image in a bent state of the flexible display screen, it is possible to suppress the image or text displayed in one display area from being projected into another display area.

[0073] It should be noted that, in this embodiment, for example as shown in FIG3, when observing an image with the foldable display screen 20 bent, the perceived reflectivity of orthographic reflection at an incident angle of 60° is adopted considering the following: As mentioned above, regarding the angle θ2 formed by the first display area 22 and the second display area 23, from the perspective of the visibility of the displayed image or text, the angle θ2 tends to be set in a manner greater than 90° and less than 180°, specifically, it can be set to around 120°; when observing an image with the foldable display screen 20 bent, the observer 25 tends to observe the image displayed in the first display area 22 and the second display area 23 by moving only the line of sight without moving the observation position; and even for the same surface, the larger the incident angle, the higher the reflectivity; and so on. The perceived reflectivity of orthographic reflection at an incident angle of 60° represents: the perceived reflectivity when light from one display area is reflected by another display area when observing an image with the flexible display screen bent.

[0074] Furthermore, in display devices, there is a problem where the color tone of the image changes depending on the viewing direction. Additionally, as mentioned above, when observing an image with the foldable display screen bent, the observer tends to move their line of sight without changing their viewing position while observing the images displayed in the first and second display areas. In this case, as illustrated in FIG3, since the position of the observer 25 is fixed, the angle of the viewing direction relative to the normal to the surface of the foldable display screen 20 on the observer 25 side is different in the first and second display areas 22 and 23. Therefore, there is a problem of different color tones of the image in the first and second display areas 22 and 23. This is not limited to foldable displays; the same problem occurs in flexible displays when observing images in a bent state.

[0075] In contrast, in this embodiment, by ensuring that the absolute value of the difference between the yellowness YI1 of the transmitted light in a direction 60° normal to the surface of the second layer of the display device laminate and the yellowness YI2 of the transmitted light in a direction 15° normal to the surface of the second layer of the display device laminate is below a predetermined value, when the display device laminate is used in a flexible display screen, the tonal difference between the images of one display area and another display area can be reduced when the image is observed in a bent state of the flexible display screen, and tonal variation can be suppressed.

[0076] For example, in Figure 2(b), if the absolute value of the difference between the yellowness YI1 of the transmitted light L2 at a direction with a normal of 60° relative to the surface S1 of the second layer side of the display device laminate 1 and the yellowness YI2 of the transmitted light L3 at a direction with a normal of 15° relative to the surface S1 of the second layer side of the display device laminate 1 is less than a predetermined value, then in the foldable display screen 20 illustrated in Figure 3, the tonal difference of the image can be reduced and tonal variation can be suppressed in the first display area 22 corresponding to the first area 12 of the display device laminate 1 and the second display area 23 corresponding to the second area 13 of the display device laminate 1. Therefore, when the display device laminate of this embodiment is used in a flexible display screen, tonal variation between the image in one display area and the image in another display area can be suppressed when the image is observed in a bent state of the flexible display screen.

[0077] It should be noted that, in this embodiment, for example as shown in FIG3, when observing an image with the foldable display screen 20 bent, the yellowness of the transmitted light in the 60° direction and the yellowness of the transmitted light in the 15° direction are adopted considering the following: As mentioned above, regarding the angle θ2 formed by the first display area 22 and the second display area 23, from the perspective of the visibility of the displayed image or text, this angle θ2 tends to be set in a manner greater than 90° and less than 180°, specifically, it can be set to about 120°; and when observing an image with the foldable display screen 20 bent, the observer 25 tends to observe the image displayed in the first display area 22 and the second display area 23 by moving only the line of sight without moving the observation position, in which case the range of the observation direction is limited; and so on. The yellowness of the transmitted light in the 60° direction and the yellowness of the transmitted light in the 15° direction respectively represent: the hue of the image in one display area and the hue of the image in the other display area when observing an image with the flexible display screen bent.

[0078] In addition, in this embodiment, yellowness is used to represent the tonal variation of a white image. The closer the yellowness is to zero, the whiter it is; a negative yellowness value represents blue, and a positive yellowness value represents yellow.

[0079] It should be noted that in Figure 3, symbol L21 represents light emitted from the second display area 23 and reflected by the first display area 22, symbol L22 represents light with a normal direction of 60° relative to the surface of the foldable display screen 20 on the observer 25 side, and symbol L23 represents light with a normal direction of 15° relative to the surface of the foldable display screen 20 on the observer 25 side.

[0080] Therefore, when the display device of this embodiment is used as a laminate in a display device, especially in a flexible display screen, the visibility can be improved in the usage mode of observing the image in a bent state of the display device.

[0081] The following describes the various components of the display device laminate in this embodiment.

[0082] 1. Characteristics of laminates used in display devices

[0083] In this embodiment, when light is incident at an angle of 60° onto the surface of the second layer of the laminate for the display device, the apparent reflectivity of the orthographically reflected light is preferably 10.0% or less, 9.5% or less, and more preferably 9.0% or less. By ensuring that the apparent reflectivity of the orthographically reflected light at the aforementioned angle of 60° is within the above range, when the laminate for the display device of this embodiment is used in a flexible display screen, when observing an image in a bent state of the flexible display screen, it is possible to suppress the image or text displayed in one display area from being reflected into another display area. The lower the apparent reflectivity of the orthographically reflected light at the aforementioned angle of 60°, the more preferred it is; the lower limit is not particularly limited, for example, it can be 0.1% or more. The apparent reflectivity of the orthographically reflected light at the aforementioned angle of 60° is preferably 0.1% or more and 10.0% or less, more preferably 0.5% or more and 9.5% or less, and even more preferably 1.0% or more and 9.0% or less.

[0084] Furthermore, when light is incident at an angle of 5° onto the surface of the second layer of the laminate for the display device, the apparent reflectivity of the orthographically reflected light is preferably 0.1% to 4.0% and less, more preferably 0.5% to 3.5% and less, and even more preferably 1.0% to 3.0% and less. By ensuring that the apparent reflectivity of the orthographically reflected light at the aforementioned angle of 5° is within the above-mentioned range, when observing an image in a state where the laminate for the display device of this embodiment is not bent, i.e., for example, when the angle θ2 in FIG3 is 180°, it is possible to suppress the observer's reflection into the display area, and to reduce the tonal difference between the images of one display area and another display area, thus suppressing tonal variations.

[0085] Here, the visual reflectance can be determined according to JIS Z8722:2009. Regarding the visual reflectance, based on the reflection spectrum obtained by incident light in the wavelength range of 380nm to 780nm onto the surface of the second layer of the laminate used for display devices, the tristimulus values ​​X, Y, and Z in the XYZ chromaticity system are determined in a 2-degree field of view of standard light C, and the Y value is taken as the visual reflectance.

[0086] In other words, visual reflectance refers to the Y value of the CIE 1931 standard colorimetric system. The following conditions can be used to measure visual reflectance.

[0087] (Measurement conditions)

[0088] • Field of view: 2°

[0089] • Illuminating element: C

[0090] • Light source: Tungsten halogen lamp

[0091] • Measurement wavelength: 380nm to 780nm, with intervals of 0.5nm.

[0092] • Scanning speed: High speed

[0093] • Slit width: 5.0nm

[0094] • S / R switching: Standard

[0095] • Automatic zeroing: Performed at 550nm after baseline scan

[0096] It should be noted that when measuring the apparent reflectance of the laminate for display devices, to prevent back reflection, a piece of black vinyl tape (e.g., "Yamato Vinyl Tape NO200-19-21", manufactured by YAMATO, 19mm wide) with a width larger than the area of ​​the measurement point is adhered to the substrate layer side of the laminate for display devices before measurement. As the measuring device for apparent reflectance, a spectrophotometer can be used, specifically the "UV-2600" spectrophotometer manufactured by Shimadzu Corporation. It should be noted that the angle of incidence refers to the angle of light incident on the second layer side of the laminate for display devices, relative to the normal to the second layer side surface.

[0097] When light is incident at an angle of 60° onto the surface of the second layer of the laminate for display device, in order to reduce the visual reflectivity of the positively reflected light, for example, (1-1) relatively reducing the refractive index of the second layer, (1-2) making the ratio of the refractive index of the first layer to the refractive index of the second layer close to 1, etc.

[0098] In the case of relatively reducing the refractive index of the second layer as described in (1-1), by making the refractive index of the second layer lower, the difference between the refractive index of the second layer and the refractive index of air can be reduced, thereby suppressing the reflection of light on the surface of the laminate for display devices on the second layer side and reducing the perceived reflectivity of the orthographically reflected light at the incident angle of 60°. In this case, it is preferable that the thickness of the second layer is relatively thick. By making the thickness of the second layer relatively thick, interference between the orthographically reflected light from the interface between the first and second layers and the orthographically reflected light on the surface of the laminate for display devices is less likely to occur, and the reflection of light on the surface of the laminate for display devices on the second layer side can be effectively suppressed. As a method to make the refractive index of the second layer lower, for example, methods such as containing resin and low-refractive-index particles with a refractive index lower than that of the resin in the second layer, or containing a low-refractive-index resin with a low refractive index in the second layer, can be cited.

[0099] Furthermore, when the ratio of the refractive index of the first layer to the refractive index of the second layer is close to 1 as described in (1-2), light reflection at the interface between the first and second layers can be suppressed, and the perceived reflectivity of the orthographically reflected light at an incident angle of 60° can be reduced. In this case, it is preferable that the second layer is thinner. When the second layer is thinner, by adjusting the refractive index and thickness of the second layer, interference of light based on the thin film can be suppressed, and the perceived reflectivity of the orthographically reflected light at an incident angle of 60° can be controlled. As a method to make the ratio of the refractive index of the first layer to the refractive index of the second layer close to 1, methods such as adjusting the refractive indices of the first and second layers can be cited.

[0100] Specific means for reducing the perceived reflectivity of orthographically reflected light at the aforementioned incident angle of 60° are described in the items of the first and second layers described later.

[0101] Furthermore, in this embodiment, the absolute value of the difference between the yellowness YI1 of transmitted light in a direction with a normal of 60° to the surface of the second layer of the display device laminate and the yellowness YI2 of transmitted light in a direction with a normal of 15° to the surface of the second layer of the display device laminate is preferably 3.0 or less, 2.5 or less, and more preferably 2.0 or less. By making the absolute value of the difference between the yellowness YI1 and YI2 within the above range, when the display device laminate of this embodiment is used in a flexible display screen, when the image is observed in a bent state of the flexible display screen, the tonal variation between the images of one display area and the other display area can be suppressed.

[0102] Furthermore, the smaller the absolute value of the difference between the yellowness values ​​YI1 and YI2, the better. There is no particular limitation on the lower limit value; for example, it can be 0.0 or higher. The absolute value of the difference between the yellowness values ​​YI1 and YI2 is preferably 0.0 or higher and 3.0 or lower, more preferably 0.2 or higher and 2.5 or lower, and even more preferably 0.5 or higher and 2.0 or lower.

[0103] Here, the yellowness (YI) can be determined according to JIS K7373:2006. Specifically, an ultraviolet-visible-near-infrared spectrophotometer can be used. Using a deuterium lamp and a tungsten halogen lamp, the transmittance is measured at 0.5 nm intervals in the range from 300 nm to 780 nm. The tristimulus values ​​X, Y, and Z in the XYZ colorimetric system are then determined in a 2-degree field of view of standard light C. Based on these X, Y, and Z values, the following formula is used for calculation.

[0104] YI = 100(1.2769X - 1.0592Z) / Y

[0105] The following conditions can be used to determine yellowness (YI).

[0106] (Measurement conditions)

[0107] • Field of view: 2°

[0108] • Illuminating element: C

[0109] • Light source: deuterium lamp and tungsten halogen lamp

[0110] • Measurement wavelength: 300nm to 780nm, with intervals of 0.5nm.

[0111] • Scanning speed: High speed

[0112] • Slit width: 5.0nm

[0113] • S / R switching: Standard

[0114] • Automatic zeroing: Performed at 550nm after baseline scan

[0115] For example, the "V-7100" manufactured by Nippon Spectrophotometer can be used as a UV-Vis-NIR spectrophotometer.

[0116] To reduce the absolute value of the difference between the yellowness YI1 and YI2 mentioned above, for example, one can take measures such as (2-1) making the ratio of the refractive index of the first layer to the refractive index of the second layer close to 1, and (2-2) relatively reducing the haze of the second layer.

[0117] When the refractive index ratio of the first layer to the second layer is close to 1 as described in (2-1), light reflection at the interface between the first and second layers can be suppressed, and the generation of interference fringes based on transmitted light can be suppressed. This reduces the transmittance change caused by the angle of transmitted light, and decreases the absolute value of the difference between the yellowness YI1 and YI2. On the other hand, if the refractive index ratio of the first layer to the second layer increases, interference fringes based on transmitted light will be generated. The generation of interference fringes affects the transmission spectrum, and the transmittance change caused by the angle of transmitted light may increase. As a result, the absolute value of the difference between the yellowness YI1 and YI2 will increase. Furthermore, when the refractive index ratio of the first layer to the second layer is close to 1, it is preferable that the second layer is thinner. With a thinner second layer, by adjusting the refractive index and thickness of the second layer, the interference of light based on the thin film can be controlled, and the generation of interference fringes based on transmitted light can be suppressed.

[0118] Furthermore, in the case of relatively reducing the haze of the second layer as described in (2-2), if the haze of the second layer decreases, the yellowness YI1 and YI2 tend to decrease, thereby reducing the absolute value of the difference between the yellowness YI1 and YI2. On the other hand, if the haze of the second layer increases, the yellowness YI1 and YI2 tend to increase, and the absolute value of the difference between the yellowness YI1 and YI2 may increase. As a method for controlling the haze of the second layer, for example, if the second layer contains resin and low-refractive-index particles with a refractive index lower than that of the resin, methods such as adjusting the content of low-refractive-index particles can be cited.

[0119] The specific means for reducing the absolute value of the difference between the aforementioned yellowness YI1 and YI2 are described in the items of the first and second layers described later.

[0120] In the laminate for display devices in this embodiment, the total light transmittance is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more. By making the total light transmittance high in this way, a laminate for display devices with good transparency can be manufactured.

[0121] Here, the total light transmittance of the laminate used in the display device can be measured according to JIS K7361-1:1999, for example, using a haze meter HM150 manufactured by the Murakami Color Technology Research Institute.

[0122] In this embodiment, the haze of the laminate for the display device is preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less. By making the haze low in this way, a laminate for the display device with good transparency can be produced.

[0123] Here, the haze of the laminate used in the display device can be measured according to JIS K-7136:2000, for example, using the HM150 haze meter manufactured by Murakami Color Technology Research Institute.

[0124] The laminate for the display device in this embodiment preferably has bending resistance. Specifically, when the dynamic bending test described below is performed on the laminate for the display device, it is preferable that no cracking or breakage occurs in the laminate for the display device.

[0125] The dynamic bending test is conducted as follows. First, a display device laminate measuring 50mm × 200mm is prepared. Then, in the dynamic bending test, as shown in Figure 4(a), the short side 1C of the display device laminate 1 and the short side 1D opposite to the short side 1C are fixed using parallel fixing parts 51. Additionally, as shown in Figure 4(a), the fixing parts 51 can slide horizontally. Next, as shown in Figure 4(b), by moving the fixing parts 51 closer together, the display device laminate 1 is deformed in a way that folds it. Then, as shown in Figure 4(c), the fixing parts 51 are moved until the distance d between the two opposing short sides 1C and 1D fixed by the fixing parts 51 of the display device laminate 1 reaches a predetermined value. Afterwards, the fixing parts 51 are moved in the opposite direction to eliminate the deformation of the display device laminate 1. As shown in Figures 4(a) to (c), by moving the fixing parts 51, the display device laminate 1 can be folded 180°. Furthermore, by conducting a dynamic bending test in a manner that prevents the bent portion 1E of the display device laminate 1 from extending from the lower end of the fixing portion 51, and by controlling the interval at which the fixing portions 51 are closest, the interval d between the two opposing short sides 1C and 1D of the display device laminate 1 can be made to a predetermined value. For example, when the interval d between the short sides 1C and 1D is 30 mm, the outer diameter of the bent portion 1E is considered to be 30 mm. For example, a durability testing machine (product name "DLDMLH-FS", manufactured by Yuasa System Equipment Co., Ltd.) can be used in the dynamic bending test.

[0126] In the laminate for display devices, it is preferable that no cracking or breakage occurs when repeatedly subjected to 200,000 180° folding dynamic bending tests with a spacing d of 30 mm between the opposing short sides 1C and 1D of the laminate for display devices 1. More preferably, it does not crack or breakage occurs when repeatedly subjected to 500,000 tests. Preferably, no cracking or breakage occurs when repeatedly subjected to 200,000 180° folding dynamic bending tests with a spacing d of 20 mm between the opposing short sides 1C and 1D of the laminate for display devices 1. Particularly preferable, no cracking or breakage occurs when repeatedly subjected to 200,000 180° folding dynamic bending tests with a spacing d of 10 mm between the opposing short sides 1C and 1D of the laminate for display devices 1.

[0127] In the dynamic bending test, the display device laminate can be folded with the second layer on the outside or with the second layer on the inside. Preferably, the display device laminate will not crack or break in either case.

[0128] 2. Floor 1 and Floor 2

[0129] In this embodiment, the first layer and the second layer are sequentially disposed on one side of the substrate layer.

[0130] In this embodiment, to ensure that the perceived reflectivity of the positively reflected light at an incident angle of 60° is below a specified value and that the absolute value of the difference between the yellowness YI1 and YI2 is below a specified value, as described above, it is preferable to have a lower refractive index of the second layer, a refractive index within a specified range of the second layer, and a thicker second layer; or to have a smaller ratio of the refractive index of the first layer to the refractive index of the second layer and a thinner second layer. Specifically, it is preferable to have a refractive index of the second layer of 1.40 to 1.50 and a thickness of 1 μm to 10 μm; or to have a ratio of the refractive index of the first layer to the refractive index of the second layer of 1.05 to 1.20 and a thickness of 50 nm to 1 μm. Two preferred embodiments of these are described below.

[0131] (1) First Embodiment

[0132] In this embodiment, the refractive index of the second layer is 1.40 or higher and 1.50 or lower, and the thickness of the second layer is 1 μm or higher and 10 μm or lower.

[0133] In this embodiment, by keeping the refractive index of the second layer within a specified range, the difference in refractive index with air can be reduced, thereby suppressing surface reflection of light from the second layer side of the laminate for display devices. Furthermore, by making the thickness of the second layer greater than a specified value, and thus relatively thick, interference between the reflected light from the interface between the first and second layers and the reflected light from the surface of the second layer side is less likely to occur, effectively suppressing surface reflection of light from the second layer side of the laminate for display devices.

[0134] Therefore, it is possible to reduce the perceived reflectivity of orthogonal reflected light at the aforementioned incident angle of 60°.

[0135] Here, the first layer is usually a resin-containing layer, and the refractive index of common resins is around 1.5. Alternatively, as described below, when the substrate layer also serves as the first layer, the substrate layer can be, for example, a resin substrate or a glass substrate. As mentioned above, the refractive index of common resins is around 1.5, and the refractive index of common glass is also around 1.5.

[0136] In this embodiment, by making the refractive index of the second layer within a specified range, the ratio of the refractive index of the first layer to the refractive index of the second layer can be made close to 1. As described above, this reduces the absolute value of the difference between the yellowness YI1 and YI2.

[0137] In addition, in this embodiment, by making the thickness of the second layer less than a specified value, the flexibility and bending resistance can be improved.

[0138] (a) Level 2

[0139] (i) Characteristics of the second layer

[0140] In this embodiment, the refractive index of the second layer is preferably 1.40 or higher, more preferably 1.43 or higher, and even more preferably 1.45 or higher.

[0141] By setting the refractive index of the second layer within the aforementioned range, the ratio of the refractive index of the first layer to the refractive index of the second layer can be made close to 1, thereby reducing the absolute value of the difference between the yellowness values ​​YI1 and YI2. Furthermore, the refractive index of the second layer is preferably 1.50 or less, more preferably 1.49 or less, and even more preferably 1.48 or less. By setting the refractive index of the second layer within the aforementioned range, the difference in refractive index with air can be reduced, suppressing surface reflection of light from the second layer side of the laminate for the display device. The refractive index of the second layer is preferably 1.40 to 1.50 or less, more preferably 1.43 to 1.49 or less, and even more preferably 1.45 to 1.48 or less.

[0142] Furthermore, in this embodiment, the ratio of the refractive index of the first layer to the refractive index of the second layer is preferably 1.00 to 1.18, more preferably 1.01 to 1.15, and even more preferably 1.02 to 1.10. By making the ratio of the refractive index of the first layer to the refractive index of the second layer close to 1, the perceived reflectivity of the positively reflected light at an incident angle of 60° can be reduced, and the absolute value of the difference between the yellowness YI1 and YI2 can be reduced. In addition, by making the ratio of the refractive index of the first layer to the refractive index of the second layer within the above range, flexibility and bend resistance can be improved, and the visibility of the flexible display screen can be improved.

[0143] Here, the refractive index of each layer refers to the refractive index relative to light with a wavelength of 550 nm. One method for measuring the refractive index is using an ellipsometer. Examples of ellipsometers include the "UVSEL" manufactured by Jobin Yvon and the "DF1030R" manufactured by Techno Synergy. The method for measuring the refractive index of the first layer and the substrate layer is the same.

[0144] In this embodiment, the thickness of the second layer is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. By making the thickness of the second layer within the above range, interference between the positively reflected light from the interface between the first and second layers and the positively reflected light from the surface of the second layer is less likely to occur, and the reflection of light from the surface of the second layer of the laminate for the display device can be effectively suppressed. In addition, the thickness of the second layer is preferably 10 μm or less, more preferably 9 μm or less, and even more preferably 8 μm or less. If the thickness of the second layer is too thick, flexibility and bending resistance may be compromised. The thickness of the second layer is preferably 1 μm or more and 10 μm or less, more preferably 3 μm or more and 9 μm or less, and even more preferably 5 μm or more and 8 μm or less.

[0145] Here, the thickness of the second layer is a value determined by cross-section along the thickness direction of the laminate used in the display device, observed using a transmission electron microscope (TEM), scanning electron microscope (SEM), or scanning transmission electron microscope (STEM). It can be the average thickness of 10 randomly selected locations. It should be noted that the same method can be used to determine the thickness of other layers in the laminate used in the display device.

[0146] (ii) Material of the second layer

[0147] There are no particular limitations on the material used for the second layer, as long as it is a material that can satisfy the aforementioned refractive index. For example, the second layer may contain resin and low-refractive-index particles with a refractive index lower than that of the resin, or it may contain a low-refractive-index resin having the aforementioned refractive index.

[0148] (ii-1) Resin and low-refractive-index particles

[0149] When the second layer contains resin and low-refractive-index particles, there are no particular limitations on the low-refractive-index particles, as long as they have a refractive index lower than that of the resin and the second layer can satisfy the above-mentioned refractive index.

[0150] The low-refractive-index particles can be either inorganic or organic. Examples of inorganic particles include silicon dioxide, magnesium fluoride, lithium fluoride, calcium fluoride, and barium fluoride. Silicon dioxide particles are preferred.

[0151] Furthermore, the low-refractive-index particles can be any of the following: solid particles, hollow particles, or porous particles. Among these, hollow particles and porous particles are preferred due to their low refractive index. Examples of hollow particles and porous particles include porous silica particles, hollow silica particles, porous polymer particles, and hollow polymer particles.

[0152] In addition, low-refractive-index particles can be surface-treated. By surface-treating low-refractive-index particles, their affinity with resins and solvents is improved, the dispersion of low-refractive-index particles becomes more uniform, and the low-refractive-index particles are less likely to aggregate. Therefore, it is possible to suppress the reduction in the transparency of the second layer, or the reduction in the coatability and film strength of the resin composition of the second layer.

[0153] As a surface treatment method, examples include surface treatment using silane coupling agents. Regarding the specific silane coupling agent, it can be, for example, the same as the silane coupling agent disclosed in Japanese Patent Application Publication No. 2013-142817.

[0154] In addition, low-refractive-index particles can be reactive particles with polymerizable functional groups on their surface.

[0155] Regarding low-refractive-index particles as reactive particles, examples include the particles used in low-refractive-index layers described in Japanese Patent Application Publication No. 2013-142817.

[0156] The average particle size of the low-refractive-index particles can be less than or equal to the thickness of the second layer, for example, less than 300 nm, less than 200 nm, less than 150 nm, or less than 100 nm. Alternatively, the average particle size can be 5 nm or more, 10 nm or more, 30 nm or more, or 50 nm or more. If the average particle size of the low-refractive-index particles is within the above range, the transparency of the second layer will not be compromised, and a good dispersion of the low-refractive-index particles can be obtained. It should be noted that if the average particle size of the low-refractive-index particles is within the above range, the average particle size can be either a primary particle size or a secondary particle size, and the low-refractive-index particles can also be chained together. The average particle size of the low-refractive-index particles is preferably 5 nm or more and less than 300 nm, more preferably 10 nm or more and less than 200 nm, further preferably 30 nm or more and less than 150 nm, and most preferably 50 nm or more and less than 100 nm.

[0157] Here, the average particle size of the low-refractive-index particles refers to the average value of 20 particles observed through a transmission electron microscope (TEM) photograph of the cross-section of the second layer.

[0158] The shape of low refractive index particles is not particularly limited; for example, spherical, chain-like, and needle-like shapes can be included.

[0159] Furthermore, when the second layer contains resin and low-refractive-index particles, the resin can be appropriately selected based on factors such as film-forming properties and film strength. Preferably, the resin is a cured resin that has been cured by irradiation with heat, ultraviolet light, electron beams, or other ionizing rays. Examples of cured resins include thermosetting resins and ionizing ray-cured resins. Examples of ionizing ray-cured resins include ultraviolet-cured resins and electron beam-cured resins. Ionizing ray-cured resins are preferred because they can improve the surface hardness of the second layer.

[0160] Here, "ionizing ray cured resin" in this specification refers to resin that has been cured by irradiation with ionizing rays. In addition, "ionizing rays" refers to energy quanta in electromagnetic waves or charged ion beams that can cause molecules to polymerize or cross-link. Examples include electromagnetic waves such as X-rays and gamma rays, as well as charged ion beams such as alpha rays and ion beams, in addition to ultraviolet rays and electron beams.

[0161] Examples of ionizing radiation-curable resins include compounds with one or more unsaturated bonds, such as compounds having acrylate functional groups. Examples of compounds with one unsaturated bond include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone. Examples of compounds with two or more unsaturated bonds include polyfunctional compounds such as polymethylolpropane tri(meth)acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate, as well as reaction products of the above polyfunctional compounds with (meth)acrylates (e.g., poly(meth)acrylates of polyols). Furthermore, "(meth)acrylate" refers to both methacrylates and acrylates.

[0162] In addition, as the aforementioned ionizing ray curable resin, low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol-polyene resins, etc., having unsaturated double bonds can also be used. Furthermore, low refractive index resins described later can also be used as the resin.

[0163] The content of resin and low-refractive-index particles in the second layer can be suitably set in such a way that the refractive index of the second layer as a whole satisfies the aforementioned refractive index. In the second layer, the content of low-refractive-index particles is preferably 10 to 300 parts by mass relative to 100 parts by mass of resin, more preferably 30 to 250 parts by mass, and even more preferably 50 to 200 parts by mass. If the content of low-refractive-index particles is too low, the desired refractive index may not be obtained. Furthermore, if the content of low-refractive-index particles is too high, the haze of the second layer increases, the aforementioned yellowness Y1 and Y2 increase, and the absolute value of the difference between the aforementioned yellowness Y1 and Y2 may become larger.

[0164] (ii-2) Low refractive index resin

[0165] When the second layer contains a low-refractive-index resin, the low-refractive-index resin can be any resin that can satisfy the above-mentioned refractive index as long as the second layer is composed of a low-refractive-index resin. Examples include fluororesins, silicone resins, acrylic resins, and olefin resins.

[0166] (ii-3) Additives

[0167] When using a UV-curable resin as the resin, the second layer may also contain a photopolymerization initiator. Furthermore, the second layer may contain various additives depending on the desired physical properties. Examples of additives include UV absorbers, antioxidants, light stabilizers, infrared absorbers, dispersants, weather resistance improvers, abrasion resistance improvers, antistatic agents, polymerization inhibitors, crosslinking agents, adhesion improvers, leveling agents, thixotropic agents, coupling agents, plasticizers, defoamers, and fillers.

[0168] (iii) Method for forming the second layer

[0169] As a method for forming the second layer, one example is a method of coating the second layer with a resin composition on the first layer and then curing it.

[0170] (b) Level 1

[0171] (i) Characteristics of the first layer

[0172] In this embodiment, as described above, the ratio of the refractive index of the first layer to the refractive index of the second layer is preferably within a specified range. It should be noted that the ratio of the refractive index of the first layer to the refractive index of the second layer is described in the second embodiment described later, and therefore its description here is omitted.

[0173] The refractive index of the first layer is not particularly limited as long as it meets the aforementioned requirement that the ratio of the refractive index of the first layer to the refractive index of the second layer is acceptable. For example, it is preferably 1.50 to 1.65, more preferably 1.52 to 1.63, and even more preferably 1.54 to 1.60. Generally, the refractive index of the first layer is greater than that of the second layer. By making the refractive index of the first layer within the aforementioned range, the ratio of the refractive index of the first layer to the refractive index of the second layer can be made close to 1, thereby reducing the absolute value of the difference between the yellowness values ​​YI1 and YI2. By making the refractive index of the first layer within the aforementioned range, the difference in refractive index with the substrate layer can be reduced, thereby suppressing light reflection at the interface between the first layer and the substrate layer.

[0174] The thickness of the first layer is preferably 1 μm to 20 μm, more preferably 3 μm to 15 μm, and even more preferably 5 μm to 10 μm. By keeping the thickness of the first layer within the above range, both flexibility and bending resistance can be achieved. However, if the thickness of the first layer is too thick, flexibility and bending resistance may be compromised.

[0175] It should be noted that, as described below, the substrate layer can also serve as the first layer, and the thickness of the first layer mentioned above refers to the thickness of the first layer when the substrate layer does not serve as the first layer.

[0176] (ii) Material of the first layer

[0177] The material used for the first layer is not particularly limited as long as it meets the aforementioned refractive index. The first layer may contain a resin. Preferably, the resin is a cured resin that has been cured by irradiation with heat or ionizing radiation such as ultraviolet light or electron beams. The cured resin can be the same as the one used in the second layer. From the perspective of scratch resistance, an ionizing radiation-cured resin is preferred because it can improve the surface hardness of the low-refractive-index layer.

[0178] When using a UV-curable resin as the resin, the first layer may also contain a photopolymerization initiator. Furthermore, the first layer may contain various additives depending on the desired physical properties. Regarding the additives, they may be the same as those used in the second layer described above.

[0179] (iii) Method for forming the first layer

[0180] As a method for forming the first layer, one example is a method of coating a resin composition for the first layer onto a substrate layer and then curing it.

[0181] (2) Second implementation method

[0182] In this embodiment, the ratio of the refractive index of the first layer to the refractive index of the second layer is 1.05 to 1.20, and the thickness of the second layer is 50 nm to 1 μm.

[0183] In this embodiment, by keeping the ratio of the refractive index of the first layer to the refractive index of the second layer within a specified range, light reflection at the interface between the first and second layers can be suppressed. Furthermore, by keeping the thickness of the second layer within a specified range and relatively thin, the refractive index and thickness of the second layer can be adjusted, thereby controlling the interference of light based on the thin film. This reduces the perceived reflectivity of the orthogonal reflected light at an incident angle of 60°. In addition, the generation of interference fringes caused by transmitted light can be suppressed, and the transmittance change caused by the angle of transmitted light can be reduced. This reduces the absolute value of the difference between the yellowness YI1 and YI2.

[0184] In addition, in this embodiment, by keeping the thickness of the second layer within a specified range, flexibility and bending resistance can be improved.

[0185] (a) Level 2

[0186] (i) Characteristics of the second layer

[0187] In this embodiment, the ratio of the refractive index of the first layer to the refractive index of the second layer is preferably 1.05 to 1.20, more preferably 1.07 to 1.18, and even more preferably 1.09 to 1.15. By making the ratio of the refractive index of the first layer to the refractive index of the second layer close to 1, the perceived reflectivity of the positively reflected light at an incident angle of 60° can be reduced, and the absolute value of the difference between the yellowness YI1 and YI2 can be reduced. Furthermore, by making the ratio of the refractive index of the first layer to the refractive index of the second layer within the above range, flexibility and bend resistance can be improved, and the visibility of the flexible display screen can be enhanced.

[0188] The refractive index of the second layer is not particularly limited as long as it satisfies the ratio of the refractive index of the first layer to the refractive index of the second layer. For example, it is preferably 1.40 or higher, more preferably 1.42 or higher, and even more preferably 1.44 or higher. This is because if the refractive index of the second layer is within the above range, it is easy to adjust it so that the ratio of the refractive index of the first layer to the refractive index of the second layer is within the specified range. Furthermore, the refractive index of the second layer is preferably 1.50 or lower, more preferably 1.49 or lower, and even more preferably 1.48 or lower. By making the refractive index of the second layer within the above range, the difference in refractive index with air can be reduced, and surface reflection of light from the second layer side of the laminate for the display device can be suppressed. The refractive index of the second layer is preferably 1.40 or higher and 1.50 or lower, more preferably 1.42 or higher and 1.49 or lower, and even more preferably 1.44 or higher and 1.48 or lower.

[0189] In this embodiment, the thickness of the second layer is appropriately adjusted according to the refractive index of the second layer. The thickness of the second layer is preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 70 nm or more. If the thickness of the second layer is too thin, the film strength may be reduced. Furthermore, the thickness of the second layer is preferably 1 μm or less, more preferably 700 nm or less, and even more preferably 500 nm or less. By keeping the thickness of the second layer within the above range, reflection can be suppressed by utilizing the light interference effect based on the thin film, and the generation of interference fringes based on transmitted light can also be suppressed. The thickness of the second layer is preferably 50 nm or more and 1 μm or less, more preferably 60 nm or more and 700 nm or less, and even more preferably 70 nm or more and 500 nm or less.

[0190] (ii) Material of the second layer

[0191] As for the material of the second layer, there are no particular limitations as long as the material of the second layer can satisfy the above-mentioned refractive index and thickness. For example, the second layer may contain resin and low-refractive-index particles with a refractive index lower than that of the resin, or it may contain low-refractive-index resin having the above-mentioned refractive index, or it may contain low-refractive-index inorganic material having the above-mentioned refractive index.

[0192] In the case where the second layer contains resin and low-refractive-index particles, the resin and low-refractive-index particles can be the same as in the first embodiment described above.

[0193] In addition, if the second layer contains a low-refractive-index resin, the low-refractive-index resin can be the same as in the first embodiment described above.

[0194] Furthermore, if the second layer contains a low-refractive-index inorganic material, the low-refractive-index inorganic material can be any inorganic material whose refractive index satisfies the aforementioned requirement. Examples include silicon dioxide, magnesium fluoride, lithium fluoride, calcium fluoride, and barium fluoride. Silicon dioxide is preferred.

[0195] When using a UV-curable resin as the resin, the second layer may also contain a photopolymerization initiator. Furthermore, the second layer may contain various additives depending on the desired physical properties. Regarding the additives, they can be the same as in the first embodiment described above.

[0196] (iii) Method for forming the second layer

[0197] The method for forming the second layer can be appropriately selected depending on the material of the second layer. When the second layer contains resin and low-refractive-index particles, or when the second layer contains a low-refractive-index resin, a method for forming the second layer can be, for example, coating the first layer with a resin composition for the second layer and then curing it. Furthermore, when the second layer contains a low-refractive-index inorganic material, methods for forming the second layer can include, for example, vacuum evaporation or sputtering.

[0198] (b) Level 1

[0199] (i) Characteristics of the first layer

[0200] The refractive index of the first layer is not particularly limited as long as it satisfies the aforementioned ratio of the refractive index of the first layer to the refractive index of the second layer. For example, it is preferably 1.47 to 1.80, more preferably 1.50 to 1.75, and even more preferably 1.53 to 1.70. Generally, the refractive index of the first layer is greater than that of the second layer. By making the refractive index of the first layer within the aforementioned range, the ratio of the refractive index of the first layer to the refractive index of the second layer can be made close to 1, thereby reducing the absolute value of the difference between the yellowness values ​​YI1 and YI2. By making the refractive index of the first layer within the aforementioned range, the difference in refractive index with the substrate layer can be reduced, thereby suppressing light reflection at the interface between the first layer and the substrate layer.

[0201] The thickness of the first layer can also be the same as in the first embodiment described above.

[0202] (ii) Material of the first layer

[0203] The material of the first layer can be the same as in the first embodiment described above.

[0204] (iii) Method for forming the first layer

[0205] The method for forming the first layer can also be the same as in the first embodiment described above.

[0206] (c) Level 3

[0207] In this embodiment, a third layer with a refractive index higher than that of the first and second layers can be disposed between the first and second layers. By sequentially stacking the first, third, and second layers with different refractive indices, light reflection can be suppressed by utilizing the light interference effect based on the thin film, and the generation of interference fringes based on transmitted light can also be suppressed.

[0208] In this embodiment, the refractive indices of the first, second, and third layers are in the order: refractive index of the second layer < refractive index of the first layer < refractive index of the third layer. The refractive index of the third layer should be higher than that of the first and second layers; for example, preferably 1.55 to 2.50, more preferably 1.60 to 2.20, and even more preferably 1.65 to 2.00. If the refractive index of the third layer is within the above range, the reflectivity can be easily adjusted by adjusting the refractive indices and thicknesses of the first, second, and third layers.

[0209] The thickness of the third layer can be appropriately adjusted according to its refractive index. The thickness of the third layer is preferably 20 nm to 500 nm, more preferably 30 nm to 300 nm, and even more preferably 40 nm to 200 nm. If the thickness of the third layer is within the above range, the reflectivity can be easily adjusted by adjusting the refractive index and thickness of the first, second, and third layers. However, if the thickness of the third layer is too thin, the film strength may decrease.

[0210] As for the material of the third layer, there are no particular limitations as long as the material of the third layer can satisfy the above-mentioned refractive index and thickness. For example, the third layer may contain resin and high refractive index particles with a higher refractive index than the resin, or it may contain high refractive index resin with the above-mentioned refractive index, or it may contain high refractive index inorganic material with the above-mentioned refractive index.

[0211] When the third layer contains resin and high-refractive-index particles, there are no particular limitations on the high-refractive-index particles, as long as they have a higher refractive index than the resin and a third layer that satisfies the aforementioned refractive index can be obtained. The high-refractive-index particles can be either inorganic or organic particles.

[0212] Examples of inorganic particles include zirconium oxide, silicon monoxide, hafnium oxide, tantalum oxide, niobium oxide, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, magnesium oxide, yttrium oxide, lanthanum fluoride, and cerium fluoride.

[0213] Furthermore, in the case where the third layer contains resin and high-refractive-index particles, the resin is the same as in the first embodiment described above.

[0214] Furthermore, if the third layer contains a high-refractive-index resin, then any resin composed of a high-refractive-index resin that satisfies the aforementioned refractive index is acceptable. Examples of such high-refractive-index resins include those that cure upon exposure to heat, ultraviolet light, or ionizing radiation such as electron beams. Examples of curing resins include thermosetting resins and ionizing radiation-curing resins. Additionally, examples of ionizing radiation-curing resins include ultraviolet-curing resins and electron beam-curing resins.

[0215] In addition, if the third layer contains a high-refractive-index inorganic material, the high-refractive-index inorganic material can be any inorganic material that can satisfy the above-mentioned refractive index of the third layer composed of high-refractive-index inorganic materials. Examples include zirconium oxide, silicon monoxide, hafnium oxide, tantalum oxide, niobium oxide, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, magnesium oxide, yttrium oxide, lanthanum fluoride, and cerium fluoride.

[0216] When using a UV-curable resin as the resin, the third layer may contain a photopolymerization initiator. Additionally, the third layer may contain various additives depending on the desired physical properties. Regarding the additives, they can be the same as those used in the second layer.

[0217] The method for forming the third layer can be appropriately selected depending on the material of the third layer. When the third layer contains resin and high-refractive-index particles, or when the third layer contains a high-refractive-index resin, a possible method for forming the third layer is to coat the first layer with a resin composition and then cure it. Alternatively, when the third layer contains a high-refractive-index inorganic material, possible methods for forming the third layer include vacuum evaporation and sputtering.

[0218] 3. Substrate layer

[0219] In this embodiment, the substrate layer is a transparent component that supports the first and second layers.

[0220] As a substrate layer, there are no particular limitations as long as it is transparent; examples include resin substrates and glass substrates.

[0221] (1) Resin substrate

[0222] The resin constituting the resin substrate is not particularly limited as long as a transparent resin substrate can be obtained; examples include polyimide-based resins, polyamide-based resins, and polyester-based resins. Examples of polyimide-based resins include polyimide, polyamide-imide, polyether-imide, and polyesterimide. Examples of polyester-based resins include polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, and polyethylene naphthalate. Among these, polyimide-based resins, polyamide-based resins, or mixtures thereof are preferred for their flexural strength, excellent hardness, and transparency; polyimide-based resins are more preferred.

[0223] As for polyimide-based resins, there are no particular limitations as long as a transparent resin substrate can be obtained. Among the aforementioned materials, polyimide and polyamide-imide are preferred. Because they can improve flexibility and bending resistance, and have a high refractive index, it is easy to adjust the reflectivity.

[0224] (a) Polyimide

[0225] Polyimide is obtained by reacting a tetracarboxylic acid component with a diamine component. As a polyimide, there are no particular limitations as long as it has transparency and rigidity. For example, from the perspective of having excellent transparency and excellent rigidity, it is preferred to have at least one structure selected from the group consisting of structures represented by the following general formula (1) and the following general formula (3).

[0226] [Chemistry 1]

[0227]

[0228] In the above general formula (1), R 1 R represents a tetravalent group that is a tetracarboxylic acid residue. 2 The group selected is at least one divalent group chosen from the group consisting of trans-cyclohexanediamine residue, trans-1,4-bis(methylenecyclohexanediamine) residue, 4,4'-diaminodiphenyl sulfone residue, 3,4'-diaminodiphenyl sulfone residue, and the divalent group represented by the general formula (2) below. n represents the number of repeating units, which is 1 or more.

[0229] [Chemistry 2]

[0230]

[0231] In the above general formula (2), R 3 and R 4 Each can be independently represented by a hydrogen atom, alkyl group, or perfluoroalkyl group.

[0232] [Chemistry 3]

[0233]

[0234] In the above general formula (3), R 5 R represents at least one tetravalent group selected from the group consisting of cyclohexanetetracarboxylic acid residues, cyclopentanetetracarboxylic acid residues, dicyclohexane-3,4,3',4'-tetracarboxylic acid residues, and 4,4'-(hexafluoroisopropylidene)phthalic acid residues. 6 This indicates a divalent group that acts as a diamine residue.

[0235] n' represents the number of repeating units, which is 1 or more.

[0236] It should be noted that "tetracarboxylic acid residue" refers to the residue obtained by removing four carboxyl groups from a tetracarboxylic acid, and it represents the same structure as the residue obtained by removing the dianhydride structure from a tetracarboxylic dianhydride. Additionally, "diamine residue" refers to the residue obtained by removing two amino groups from a diamine.

[0237] In the above general formula (1), R 1 The residue is a tetracarboxylic acid residue, which can be obtained by removing the dianhydride structure from a tetracarboxylic dianhydride. Examples of tetracarboxylic dianhydrides include the substance described in International Publication No. 2018 / 070523. R in the above general formula (1) 1 From the perspective of improving transparency and rigidity, it is preferable to include at least one residue selected from the group consisting of 4,4'-(hexafluoroisopropylene)phthalic acid residue, 3,3',4,4'-biphenyltetracarboxylic acid residue, pyromellitic acid residue, 2,3',3,4'-biphenyltetracarboxylic acid residue, 3,3',4,4'-benzophenone tetracarboxylic acid residue, 3,3',4,4'-diphenyl sulfone tetracarboxylic acid residue, 4,4'-oxophthalic acid residue, cyclohexane tetracarboxylic acid residue, and cyclopentane tetracarboxylic acid residue. It is even more preferable to include at least one residue selected from the group consisting of 4,4'-(hexafluoroisopropylene)phthalic acid residue, 4,4'-oxophthalic acid residue, and 3,3',4,4'-diphenyl sulfone tetracarboxylic acid residue.

[0238] R 1 In this mixture, the total content of these suitable residues is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

[0239] Additionally, as R 1 Preferably, a tetracarboxylic acid residue group (Group A) suitable for improving rigidity, selected from at least one of the group consisting of 3,3',4,4'-biphenyltetracarboxylic acid residues, 3,3',4,4'-benzophenone tetracarboxylic acid residues, and pyromellitic acid residues, is used in combination with a tetracarboxylic acid residue group (Group B) suitable for improving transparency, selected from at least one of the group consisting of 4,4'-(hexafluoroisopropylidene)diphthalic acid residues, 2,3',3,4'-biphenyltetracarboxylic acid residues, 3,3',4,4'-diphenylsulfone tetracarboxylic acid residues, 4,4'-oxophthalic acid residues, cyclohexanetetracarboxylic acid residues, and cyclopentanetetracarboxylic acid residues.

[0240] In this case, regarding the content ratio of the tetracarboxylic acid residue group (Group A) suitable for improving rigidity and the tetracarboxylic acid residue group (Group B) suitable for improving transparency, the tetracarboxylic acid residue group (Group A) suitable for improving rigidity is preferably 0.05 moles or more and 9 moles or less, more preferably 0.1 moles or more and 5 moles or less, and even more preferably 0.3 moles or more and 4 moles or less, relative to 1 mole of the tetracarboxylic acid residue group (Group B) suitable for improving transparency.

[0241] R in the above general formula (1) 2From the perspective of improving transparency and rigidity, it is preferable to select at least one divalent group selected from the group consisting of 4,4'-diaminodiphenyl sulfone residues, 3,4'-diaminodiphenyl sulfone residues, and divalent groups represented by the above general formula (2), and more preferably selected from 4,4'-diaminodiphenyl sulfone residues, 3,4'-diaminodiphenyl sulfone residues, and R 3 and R 4 It is at least one divalent group in the group consisting of divalent groups represented by the above general formula (2) of perfluoroalkyl.

[0242] R in the above general formula (3) 5 From the perspective of improving transparency and rigidity, it is preferable to include 4,4'-(hexafluoroisopropylidene) phthalic acid residues, 3,3',4,4'-diphenyl sulfone tetracarboxylic acid residues, and oxyphthalic acid residues.

[0243] R 5 In this mixture, these suitable residues preferably contain 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

[0244] In the above general formula (3), R 6 The residue is a diamine residue, which can be a residue obtained by removing two amino groups from a diamine. Examples of diamines include the substance described in International Publication No. 2018 / 070523. R in the above general formula (3) 6 From the perspective of improving transparency and rigidity, it is preferable to include residues selected from 2,2'-bis(trifluoromethyl)benzidine, bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4'-diaminodiphenyl sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]sulfone, 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether, 1,4-bis[4-amino-2-(trifluoromethyl)phenoxy]benzene ...bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)phenyl]benzene, bis[4-(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy) The residue contains at least one divalent group selected from the group consisting of 2,2'-bis(trifluoromethyl)benzidine residue, 4,4'-diamino-2-(trifluoromethyl)diphenyl ether residue, 4,4'-diaminobenzoylaniline residue, N,N'-bis(4-aminophenyl)terephthalamide residue, and 9,9-bis(4-aminophenyl)fluorene residue, and more preferably includes at least one divalent group selected from the group consisting of 2,2'-bis(trifluoromethyl)benzidine residue, bis[4-(4-aminophenoxy)phenyl]sulfone residue, and 4,4'-diaminodiphenyl sulfone residue.

[0245] R 6In this mixture, the total content of these suitable residues is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

[0246] Additionally, as R 6 Preferably, a group of diamine residues suitable for improving rigidity selected from at least one of the group consisting of bis[4-(4-aminophenoxy)phenyl]sulfone residues, 4,4'-diaminobenzoylaniline residues, N,N'-bis(4-aminophenyl)terephthalamide residues, p-phenylenediamine residues, m-phenylenediamine residues, and 4,4'-diaminodiphenylmethane residues is combined with a group of diamine residues selected from 2,2'-bis(trifluoromethyl)benzidine residues, 4,4'-diaminodiphenylsulfone residues, and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. The group of at least one of the following groups of residues, bis[4-(3-aminophenoxy)phenyl]sulfone residues, 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether residues, 1,4-bis[4-amino-2-(trifluoromethyl)phenoxy]benzene residues, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane residues, 4,4'-diamino-2-(trifluoromethyl)diphenyl ether residues, and 9,9-bis(4-aminophenyl)fluorene residues, is suitable for use in combination with diamine residues suitable for improving transparency (Group D).

[0247] In this case, regarding the content ratio of the diamine residue group (group C) suitable for improving rigidity and the diamine residue group (group D) suitable for improving transparency, the diamine residue group (group C) suitable for improving rigidity is preferably 0.05 moles or more and 9 moles or less, more preferably 0.1 moles or more and 5 moles or less, and more preferably 0.3 moles or more and 4 moles or less, relative to 1 mole of the diamine residue group (group D) suitable for improving transparency.

[0248] In the structures represented by the above general formulas (1) and (3), n and n' each independently represent the number of repeating units, which is 1 or more. The number of repeating units n in the polyimide can be appropriately selected according to the structure, and there is no particular limitation. The average number of repeating units can be, for example, 10 or more and 2000 or less, preferably 15 or more and 1000 or less.

[0249] Furthermore, a portion of the polyimide may contain a polyamide structure. Examples of possible polyamide structures include polyamide-imide structures containing tricarboxylic acid residues such as trimellitic anhydride, and polyamide structures containing dicarboxylic acid residues such as terephthalic acid.

[0250] From the perspectives of improving transparency and surface hardness, R is preferred. 1 Or R 5 The tetravalent group of the tetracarboxylic acid residue, and as R2 Or R 6 At least one of the divalent groups of the diamine residues comprises an aromatic ring, and comprises at least one of the group consisting of (i) a fluorine atom, (ii) an aliphatic ring, and (iii) a structure in which aromatic rings are linked together by alkylene groups that can be substituted with sulfonyl or fluorine groups. By including at least one of tetracarboxylic acid residues having an aromatic ring and diamine residues having an aromatic ring in the polyimide, the molecular backbone becomes more rigid, its orientation increases, and its surface hardness improves. However, the rigid aromatic ring backbone tends to extend the absorption wavelength to longer wavelengths, and the transmittance in the visible light region tends to decrease. On the other hand, when the polyimide includes (i) a fluorine atom, the electronic states within the polyimide backbone are less prone to charge transfer, thereby improving transparency.

[0251] Furthermore, when polyimides contain (ii) aliphatic rings, the movement of charges within the polyimide backbone can be suppressed by cleaving the conjugation of π electrons, thus improving transparency. Additionally, when polyimides contain (iii) a structure in which aromatic rings are linked together using alkylene groups that can be substituted with sulfonyl or fluorine groups, the movement of charges within the polyimide backbone can be suppressed by cleaving the conjugation of π electrons, thus improving transparency.

[0252] Among these, focusing on improving transparency and surface hardness, as R... 1 Or R 5 The tetravalent group of the tetracarboxylic acid residue, and as R 2 Or R 6 At least one of the divalent groups of the diamine residues preferably comprises an aromatic ring and a fluorine atom, as R 2 Or R 6 The divalent group of the diamine residue preferably includes an aromatic ring and a fluorine atom.

[0253] As a specific example of such polyimide, one can cite the substance with a specific structure described in International Publication No. 2018 / 070523.

[0254] Polyimides can be synthesized using known methods. Alternatively, commercially available polyimides can be used. Examples of commercially available polyimides include Neoprim (a registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd.

[0255] The weight-average molecular weight of the polyimide is preferably 3,000 to 500,000, more preferably 5,000 to 300,000, and even more preferably 10,000 to 200,000. If the weight-average molecular weight is too small, sufficient strength may not be obtained; if the weight-average molecular weight is too large, the viscosity increases and the solubility decreases, so a substrate layer with a smooth surface and uniform thickness may not be obtained.

[0256] It should be noted that the weight-average molecular weight of polyimide can be determined by gel permeation chromatography (GPC). Specifically, polyimide is prepared into a 0.1% (w / w) N-methylpyrrolidone (NMP) solution, and the developing solvent is a 30 mmol% LiBr-NMP solution with a water content of less than 500 ppm. The determination is performed using a Tosoh GPC apparatus (HLC-8120, using a SHODEX GPC LF-804 column) at a sample injection volume of 50 μL, a solvent flow rate of 0.4 mL / min, and a temperature of 37°C. The weight-average molecular weight is determined using a polystyrene standard sample of the same concentration as the sample.

[0257] (b) Polyamide imide

[0258] As for polyamide-imide, there is no particular limitation as long as the material can produce a transparent resin substrate. Examples include materials having a first block comprising structural units from dianhydrides and diamines, and a second block comprising structural units from aromatic dicarbonyl compounds and aromatic diamines. In the aforementioned polyamide-imide, the dianhydride may, for example, comprise biphenyltetracarboxylic acid dianhydride (BPDA) and 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). Furthermore, the diamine may comprise bis(trifluoromethyl)benzidine (TFDB). That is, the aforementioned polyamide-imide has a structure formed by imidizing a polyamide-imide precursor having a first block copolymerized from monomers comprising dianhydrides and diamines, and a second block copolymerized from monomers comprising aromatic dicarbonyl compounds and aromatic diamines.

[0259] The aforementioned polyamide-imide has a first block containing an imide bond and a second block containing an amide bond, thereby exhibiting not only excellent optical properties but also excellent thermal and mechanical properties.

[0260] In particular, by using bis(trifluoromethyl)benzidine (TFDB) as the diamine forming the first block, thermal stability and optical properties can be improved. Furthermore, by using 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic acid dianhydride (BPDA) as the dianhydrides forming the first block, improved birefringence and ensured heat resistance can be achieved.

[0261] The dianhydrides forming the first block include two dianhydrides, namely 6FDA and BPDA. In the first block, the polymer formed by the combination of TFDB and 6FDA and the polymer formed by the combination of TFDB and BPDA can be contained separately on the basis of separate repeating units, or they can be regularly arranged within the same repeating unit, or they can be contained in a completely random arrangement.

[0262] In the monomers forming the first block, BPDA and 6FDA are preferably contained as dianhydrides in a molar ratio of 1:3 to 3:1. This is because it not only ensures optical properties but also suppresses the reduction of mechanical properties and heat resistance, resulting in excellent birefringence.

[0263] The molar ratio of the first block to the second block is preferably 5:1 to 1:1.

[0264] When the content of the second block is significantly low, the improved thermal stability and mechanical properties resulting from the second block may not be fully realized. Furthermore, when the content of the second block is significantly higher than that of the first block, although thermal stability and mechanical properties are improved, optical properties deteriorate, such as reduced yellowness and transmittance, while birefringence increases. It should be noted that the first and second blocks can be random copolymers or block copolymers. The repeating units of the blocks are not particularly limited.

[0265] Examples of aromatic dicarbonyl compounds forming the second block include one or more selected from the group consisting of p-Terephthaloyl chloride (TPC), terephthalic acid, isophthaloyl dichloride, and 4,4'-benzoyl dichloride. Preferably, one or more selected from p-Terephthaloyl chloride (TPC) and isophthaloyl dichloride are preferred.

[0266] Examples of diamines forming the second block include, for instance, one or more diamines having a soft group selected from the group consisting of: 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 4,4'-diaminodiphenyl sulfone (4DDS), 3,3'-diaminodiphenyl sulfone (3DDS), 2,2-bis(4-(4-aminophenoxy)phenylpropane (BAPP), and 4,4'-diaminodiphenylpropane (6HDA). ), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,4-bis(4-aminophenoxy)biphenyl (BAPB), 4,4'-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (6FAPBP), 3,3-diamino-4,4-dihydroxydiphenyl sulfone (DABS), 2,2-bis(3-amino-4-hydroxyphenyl)propane (BAP), 4,4'-diaminodiphenylmethane (DDM), 4,4'-oxodiphenylamine (4-ODA), and 3,3'-oxodiphenylamine (3-ODA).

[0267] While aromatic dicarbonyl compounds readily achieve high thermal stability and mechanical properties, they may exhibit high birefringence due to the benzene ring within the molecular structure. Therefore, to suppress the decrease in birefringence caused by the second block, diamines preferably contain a soft group in their molecular structure. Specifically, diamines are more preferably selected from one or more of bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 4,4'-diaminodiphenyl sulfone (4DDS), and 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP). In particular, diamines with longer soft groups (such as BAPSM) and substituents located in the meta position exhibit superior birefringence.

[0268] The polyamide-imide precursor containing a first block (which is a copolymer of a dianhydride containing biphenyltetracarboxylic acid dianhydride (BPDA) and 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and a diamine of bis(trifluoromethylbenzidine) (TFDB)) and a second block (which is a copolymer of an aromatic dicarbonyl compound and an aromatic diamine) has a weight-average molecular weight, as determined by GPC, preferably between 200,000 and 215,000, and a viscosity, preferably between 2,400 poise and 2,600 poise.

[0269] Polyamide-imides can be obtained by imidizing polyamide-imide precursors. Alternatively, polyamide-imide films can be obtained using polyamide-imides.

[0270] For methods of imidizing polyamide-imide precursors and methods of manufacturing polyamide-imide films, please refer to, for example, Japanese Patent Publication No. 2018-506611.

[0271] (2) Glass substrate

[0272] As for the glass constituting the glass substrate, there are no particular limitations as long as it is transparent; examples include silicate glass and silica glass. Among these, borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass are preferred, and alkali-free glass is more preferred. Commercially available glass substrates include, for example, Nippon Electric Glass's G-Leaf ultra-thin sheet glass and Matsunami Glass Industry Co., Ltd.'s ultra-thin film glass.

[0273] Furthermore, the glass constituting the glass substrate is preferably chemically strengthened glass. Chemically strengthened glass is preferred from the perspective of excellent mechanical strength and the ability to be thinned accordingly. Typically, chemically strengthened glass involves partial ion exchange, where sodium is replaced with potassium or similar substances near the glass surface, thereby creating a glass whose mechanical properties are strengthened using chemical methods, resulting in a compressive stress layer on the surface.

[0274] Examples of glasses that form the substrate of chemically strengthened glass include aluminosilicate glass, soda lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass.

[0275] Commercially available products that serve as substrates for chemically strengthened glass include Corning's Gorilla Glass, AGC's Dragontrail, and Schott's chemically strengthened glass.

[0276] (3) Composition of the substrate layer

[0277] The substrate layer can also serve as the first layer mentioned above. When the substrate layer also serves as the first layer, since a high refractive index is required to improve flexibility and bending resistance, polyimide resins, polyamide resins, polyester resins, etc., are preferred.

[0278] There is no particular limitation on the thickness of the substrate layer, as long as it is flexible, and it can be appropriately selected according to the type of substrate layer.

[0279] The thickness of the resin substrate is preferably 10 μm or more and 100 μm or less, more preferably 25 μm or more and 80 μm or less. By making the thickness of the resin substrate within the above range, good flexibility and sufficient hardness can be obtained. In addition, curling of the laminate for the display device can be suppressed. Furthermore, it is also preferable in terms of the lightweight nature of the laminate for the display device.

[0280] The thickness of the glass substrate is preferably 200 μm or less, more preferably 15 μm or more and 100 μm or less, even more preferably 20 μm or more and 90 μm or less, and particularly preferably 25 μm or more and 80 μm or less. By making the thickness of the glass substrate within the above range, good flexibility and sufficient hardness can be obtained. In addition, curling of the laminate for the display device can be suppressed. Furthermore, it is also preferable in terms of the lightweight nature of the laminate for the display device.

[0281] 4. Other layers

[0282] In the laminate for the display device in this embodiment, in addition to the substrate layer, the first layer and the second layer described above, other layers may also be included.

[0283] (1) Hard coating

[0284] For example, as shown in FIG5, the laminate for the display device in this embodiment may have a hard coating layer 5 between the substrate layer 2 and the first layer 3. The hard coating layer is a component used to improve surface hardness. By configuring the hard coating layer, load resistance can be improved. In particular, when the substrate layer is a resin substrate, the load resistance can be effectively improved by configuring the hard coating layer.

[0285] The refractive index of the hard coating is not particularly limited as long as it meets the refractive index of the first layer described above. For example, it is preferably 1.47 or higher and 1.80 or lower, more preferably 1.50 or higher and 1.75 or lower, and even more preferably 1.53 or higher and 1.70 or lower. By making the refractive index of the hard coating within the above range, the difference in refractive index between the hard coating and the substrate layer and the first layer can be reduced, thereby suppressing light reflection at the interface between the hard coating and the first layer and at the interface between the hard coating and the substrate layer.

[0286] Materials that can be used as hard coatings include, for example, organic materials, inorganic materials, and organic-inorganic composite materials.

[0287] The material for the hard coating is preferably an organic material. As an organic material, a curing resin that has been cured by irradiation with heat or ionizing radiation such as ultraviolet light or electron beams is preferred. The curing resin can be the same as that used in the first and second layers described above.

[0288] The hard coating may contain a polymerization initiator as needed. Suitable polymerization initiators include free radical polymerization initiators, cationic polymerization initiators, and other similar initiators. These initiators can be decomposed by at least one of light irradiation and heating, generating free radicals or cations for free radical polymerization and cationic polymerization. It should be noted that there are also cases in the functional layer where the polymerization initiator completely decomposes without leaving any residue.

[0289] When using a UV-curable resin as the resin, the hard coating may contain a photopolymerization initiator. Furthermore, the hard coating may contain various additives depending on the desired physical properties. Regarding the additives, they may be the same as those used in the first and second layers described above.

[0290] The thickness of the hard coating can be appropriately selected based on the function of the hard coating and the application of the laminate for the display device. The thickness of the hard coating is preferably 0.5 μm to 50 μm, more preferably 1.0 μm to 40 μm, even more preferably 1.5 μm to 30 μm, and particularly preferably 2.0 μm to 20 μm. When the thickness of the hard coating is within the above range, sufficient hardness as a hard coating can be obtained.

[0291] As a method for forming a hard coating, for example, a method of applying a resin composition for a hard coating onto the aforementioned substrate layer and then curing it can be described.

[0292] (2) Impact Absorption Layer

[0293] In this embodiment, the laminate for the display device may have an impact-absorbing layer 6 between the substrate layer 2 and the first layer 3, as shown in FIG. 6, or an impact-absorbing layer 6 may be provided on the surface of the substrate layer 2 opposite to the first layer 3, as shown in FIG. 7. By configuring the impact-absorbing layer, the impact can be absorbed when an impact is applied to the laminate for the display device, thereby improving its impact resistance. In addition, when the substrate layer is a glass substrate, the breakage of the glass substrate can be suppressed.

[0294] There are no particular limitations on the materials used for the impact-absorbing layer, as long as it can produce an impact-absorbing layer that is both shock-absorbing and transparent. Examples include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), urethane resins, epoxy resins, polyimides, polyamide-imides, acrylic resins, triacetyl cellulose (TAC), and silicone resins. One of these materials can be used alone, or two or more can be used in combination.

[0295] The shock-absorbing layer may contain further additives as needed. Examples of additives include inorganic particles, organic particles, ultraviolet absorbers, antioxidants, light stabilizers, surfactants, and adhesion enhancers.

[0296] The thickness of the impact-absorbing layer can be any thickness that can absorb the impact. For example, it is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 120 μm or less, and even more preferably 15 μm or more and 100 μm or less.

[0297] As an impact-absorbing layer, a resin film can be used, for example. Alternatively, an impact-absorbing layer can also be formed, for example, by coating the aforementioned substrate layer with a composition for an impact-absorbing layer.

[0298] (3) Apply adhesive layer

[0299] For example, as shown in FIG6, the display device laminate in this embodiment may have an adhesive layer 7 on the side of the substrate layer 2 opposite to the first layer 3. With the help of the adhesive layer, the display device laminate can be bonded to, for example, a display panel.

[0300] As for the adhesive used in the bonding layer, there are no particular limitations as long as the adhesive is transparent and can be used to bond the display device to the display panel in a laminate. Examples include thermosetting adhesives, UV-curing adhesives, two-component curing adhesives, hot melt adhesives, pressure-sensitive adhesives (so-called adhesives), etc.

[0301] As shown in Figure 7, when the adhesive layer 7, the impact-absorbing layer 6, and the interlayer adhesive layer 9 (described later) are sequentially arranged, the adhesive layer and the interlayer adhesive layer preferably contain a pressure-sensitive adhesive, i.e., a pressure-sensitive adhesive layer is preferred. Typically, the pressure-sensitive adhesive layer is the softer layer among the aforementioned adhesive layers containing adhesive. By arranging the impact-absorbing layers between the relatively soft pressure-sensitive adhesive layers, impact resistance can be improved. It is believed that because the pressure-sensitive adhesive layer is relatively soft and easily deformable, when an impact is applied to the laminate for the display device, the deformation of the impact-absorbing layer is not suppressed by the pressure-sensitive adhesive layer, and the impact-absorbing layer easily deforms, thus achieving a greater impact absorption effect.

[0302] The thickness of the adhesive layer for attachment is preferably 10 μm to 100 μm, more preferably 25 μm to 80 μm, and even more preferably 40 μm to 60 μm. If the thickness of the adhesive layer for attachment is too thin, the laminate for the display device may not be able to bond sufficiently to the display panel, etc. In addition, if the thickness of the adhesive layer for attachment is too thick, flexibility may be compromised.

[0303] As an adhesive layer for attachment, an adhesive film can be used, for example. Alternatively, an adhesive composition can be applied to a support or substrate layer to form an adhesive layer for attachment.

[0304] (4) Anti-fouling layer

[0305] For example, as shown in Figure 8, in this embodiment, the laminate for the display device may have an anti-fouling layer 8 on the surface of the second layer 4 opposite to the first layer 3. By configuring the anti-fouling layer, the laminate for the display device can be given anti-fouling properties. It should be noted that in this embodiment, since the thickness of the anti-fouling layer is relatively thin as described below, it is presumed that it will not affect thin-film interference.

[0306] As a material for the antifouling layer, common antifouling materials such as fluorine compounds and silicone compounds can be used.

[0307] In this embodiment, in the usage mode of observing the images of the first display area and the second display area in a bent state, fluorine compounds are preferred from the aspects of providing anti-fouling properties and transparency for repeatedly wiping away fingerprints or dirt attached to the first display area or the second display area, and maintaining the visibility of the images.

[0308] Examples of the aforementioned fluorinated compounds include fluorinated compounds having reactive functional groups such as (meth)acryloyl, vinyl, epoxy, oxobutyl, and olefinic unsaturated groups; fluorinated compounds having the aforementioned reactive functional groups and silicon; and examples include fluorinated compounds having fluoroalkylene groups in the main chain; fluorinated compounds having fluoroalkylene groups in both the main chain and side chains; fluorinated compounds having fluoroalkyl groups; fluorinated compounds having siloxane bonds; fluorinated compounds having silicones containing reactive functional groups; fluorinated compounds having reactive functional groups and perfluoropolyether groups; and fluorinated compounds having silane units containing perfluoropolyether groups.

[0309] In this embodiment, fluorinated compounds having silane units comprising perfluoropolyether groups are particularly preferred.

[0310] The thickness of the antifouling layer is preferably 1 nm to 30 nm, more preferably 2 nm to 20 nm, and even more preferably 3 nm to 10 nm. If the thickness of the antifouling layer is within the above range, good antifouling properties and durability can be achieved.

[0311] As a method for forming the antifouling layer, it can be appropriately selected according to the material of the antifouling layer. For example, methods such as coating the second layer with a resin composition for the antifouling layer and curing it, vacuum evaporation, and sputtering can be used.

[0312] (5) Interlayer adhesive layer

[0313] In the laminated body for display device in this embodiment, interlayer adhesive layers can be disposed between each layer.

[0314] The adhesive used in the interlayer bonding layer can be the same as the adhesive used in the bonding layer described above.

[0315] The thickness and formation method of the interlayer adhesive layer can be the same as those of the adhesive layer used for attachment described above.

[0316] 5. Applications of laminates for display devices

[0317] The laminate for a display device in this embodiment can be used as a front panel disposed closer to the viewer than the display panel itself. Specifically, the laminate for a display device in this embodiment can be appropriately used as the front panel in flexible display devices such as foldable displays, rollable displays, and bendable displays. In particular, the laminate for a display device in this embodiment improves visibility in usage modes where the image is viewed while the display device is bent, and therefore can be appropriately used as the front panel in foldable displays.

[0318] In addition, the display device laminate in this embodiment can be used, for example, in the front panel of display devices such as smartphones, tablet terminals, wearable terminals, personal computers, televisions, digital signage, public information displays (PIDs), and vehicle displays.

[0319] B. Display device

[0320] The display device in this embodiment includes: a display panel; and a display device laminate disposed on the observer side of the display panel.

[0321] Figure 9 is a schematic cross-sectional view showing an example of the display device in this embodiment. As shown in Figure 9, the display device 30 includes a display panel 31 and a display device laminate 1 disposed on the observer side of the display panel 31. In the display device 30, the display device laminate 1 and the display panel 31 can be bonded together, for example, by means of an adhesive layer 7 for attaching the display device laminate 1.

[0322] When the display device in this embodiment is disposed on the surface of the display device using a laminate, it is disposed such that the second layer is on the outside and the substrate layer is on the inside.

[0323] There are no particular limitations on the method of arranging the display device in this embodiment on the surface of the display device using a laminate, for example, a method using an adhesive layer can be cited.

[0324] As the display panel in this embodiment, examples include display panels used in display devices such as organic EL display devices and liquid crystal display devices.

[0325] The display device in this embodiment may have a touch panel component between the display panel and the display device laminate.

[0326] The display device in this embodiment is preferably a flexible display device such as a foldable display screen, a rollable display screen, or a bendable display screen.

[0327] Furthermore, the display device in this embodiment is preferably foldable. That is, the display device in this embodiment is preferably a foldable display screen. The display device in this embodiment has excellent visibility when used in a bent state to view images, making it suitable as a foldable display screen.

[0328] II. Second Implementation

[0329] Next, the display device laminate and the display device of the second embodiment will be described.

[0330] A. Laminated substrate for display devices

[0331] The display device laminate in this embodiment is a display device laminate having a substrate layer and a functional layer. When light is incident on the functional layer side of the display device laminate at an incident angle of 60°, the perceived reflectivity of the orthogonal reflected light is 10.0% or less. After surface modification of the functional layer side of the display device laminate, during a steel wool test in which the functional layer side of the display device laminate is rubbed back and forth 100 times with a specified load using #0000 steel wool, the maximum load that prevents peeling of the functional layer is 1.0 kg / cm². 2 Above 2.0kg / cm 2 the following.

[0332] Figure 10 is a schematic cross-sectional view showing an example of a laminate for a display device according to this embodiment. As shown in Figure 10, the laminate for a display device 41 has a substrate layer 42 and a functional layer 43. Furthermore, as illustrated in Figure 11(a), when light is incident at an angle of 60° onto the functional layer side surface S41 of the laminate for a display device 41, the perceived reflectivity of the positively reflected light L1 is below a specified value. Additionally, although not shown, after surface modification of the functional layer 43 side surface S41 of the laminate for a display device 41, when a steel wool test is conducted where a specified load is applied to the functional layer 43 side surface S41 of the laminate for a display device 41 using #0000 steel wool and subjected to 100 cycles of reciprocating friction, the maximum load that prevents peeling of the functional layer 43 is within a specified range.

[0333] In this embodiment, the maximum load at which the functional layer does not peel off is used as an indicator for evaluating the hardness and adhesion of the functional layer when a steel wool test is performed on the surface of the functional layer side of the laminate for display devices. If the hardness or adhesion of the functional layer is low, the maximum load tends to decrease. On the other hand, if the hardness or adhesion of the functional layer is high, the maximum load tends to increase. If the adhesion of the functional layer is insufficient, warping may occur at the bending point when the laminate for display devices is repeatedly bent. On the other hand, if the hardness of the functional layer is too high or the adhesion of the functional layer is excessive, cracks or fractures may occur at the bending point when the laminate for display devices is repeatedly bent.

[0334] In this embodiment, by ensuring that the maximum load at which the functional layer side of the laminate for display devices does not peel off during a steel wool test after surface modification is above a predetermined value, warping at the bending portion can be suppressed when the laminate for display devices is repeatedly bent. Furthermore, by ensuring that the maximum load at which the functional layer does not peel off during a steel wool test after surface modification is below a predetermined value, cracks or breakage at the bending portion can be suppressed. Therefore, when the laminate for display devices is used in a flexible display screen, the visibility of images or text at the bending portion can be improved.

[0335] Here, for example, in a foldable display screen, we assume a usage configuration where the image is viewed in a bent state. In such a configuration, as shown in FIG12, the foldable display screen 20 has a first display area 22 and a second display area 23 bounded by the bend 21. In this case, the image or text displayed in the second display area 23 is projected onto the first display area 22, or the image or text displayed in the first display area 22 is projected onto the second display area 23, resulting in reduced image or text visibility. This is not limited to foldable displays; the same problem arises in flexible displays when the image is viewed in a bent state.

[0336] In contrast, in this embodiment, when light is incident at an angle of 60° onto the surface S41 of the functional layer side of the laminate 41 for display device, the visual reflectivity of the positively reflected light L1 is below a predetermined value. As a result, when the laminate for display device is used in a flexible display screen, when the image is viewed in a bent state of the flexible display screen, it is possible to suppress the image or text displayed in one display area from being reflected into another display area.

[0337] For example, in a foldable display screen, when viewing an image in a bent state, the angle θ2 between the first display area 22 and the second display area 23 illustrated in FIG12 is tended to be set to a value greater than 90° and less than 180° from the perspective of the visibility of the displayed image or text; specifically, it can be set to around 120°. When a display device laminate is arranged on the observer 25 side of such a foldable display screen 20, as shown in FIG11(b), the display device laminate 41 has a first area 12 and a second area 13 bounded by the bend 11, and the angle θ1 between the first area 12 and the second area 13 is the same as the aforementioned angle θ2.

[0338] For example, in Figure 11(b), when light is incident at an angle of 60° onto the surface S41 of the functional layer side of the laminate 41 for the display device, if the apparent reflectivity of the positively reflected light L1 is below a predetermined value, then in the foldable display screen 20 illustrated in Figure 12, it is possible to suppress the reflection of light from the second display area 23 corresponding to the second region 13 of the laminate 41 for the display device by the first display area 22 corresponding to the first region 12 of the laminate 41 for the display device. Therefore, when the laminate for the display device of this embodiment is used in a flexible display screen, when viewing an image in a bent state of the flexible display screen, it is possible to suppress the image or text displayed in one display area from being reflected into another display area. Thus, visibility can be improved in usage modes where the image is viewed in a bent state of the display device.

[0339] It should be noted that, in this embodiment, for example as shown in FIG12, when observing an image with the foldable display screen 20 bent, the perceived reflectivity of orthographic reflection at an incident angle of 60° is adopted considering the following: As mentioned above, regarding the angle θ2 formed by the first display area 22 and the second display area 23, from the perspective of the visibility of the displayed image or text, the angle θ2 tends to be set in a manner greater than 90° and less than 180°, specifically, it can be set to about 120°; when observing an image with the foldable display screen 20 bent, the observer 25 tends to observe the image displayed in the first display area 22 and the second display area 23 by moving only the line of sight without moving the observation position; and even for the same surface, the larger the incident angle, the higher the reflectivity; and so on. The perceived reflectivity of orthographic reflection at an incident angle of 60° represents: the perceived reflectivity when light from one display area is reflected by another display area when observing an image with the flexible display screen bent.

[0340] It should be noted that in Figure 12, the symbol L21 represents light emitted from the second display area 23 and reflected by the first display area 22.

[0341] Therefore, when the display device of this embodiment is used as a laminate in a display device, especially in a flexible display screen, the visibility of the image or text at the curved portion can be improved, and the visibility can be improved in the usage mode of observing the image in the bent state of the display device.

[0342] The following describes the various components of the display device laminate in this embodiment.

[0343] 1. Characteristics of laminates used in display devices

[0344] In this embodiment, when light is incident at an angle of 60° onto the surface of the functional layer side of the laminate for the display device, the apparent reflectivity of the orthogonal reflected light is preferably 10.0% or less, 9.5% or less, and more preferably 9.0% or less. By ensuring that the apparent reflectivity of the orthogonal reflected light at the aforementioned angle of 60° is within the above range, when the laminate for the display device of this embodiment is used in a flexible display screen, when observing an image in a bent state of the flexible display screen, it is possible to suppress the image or text displayed in one display area from being reflected into another display area. The lower the apparent reflectivity of the orthogonal reflected light at the aforementioned angle of 60°, the more preferred it is; the lower limit is not particularly limited, for example, it can be 0.1% or more. The apparent reflectivity of the orthogonal reflected light at the aforementioned angle of 60° is preferably 0.1% or more and 10.0% or less, more preferably 0.5% or more and 9.5% or less, and even more preferably 1.0% or more and 9.0% or less.

[0345] Furthermore, when light is incident at an angle of 5° onto the surface of the functional layer of the laminate for the display device, the apparent reflectivity of the orthogonal reflected light is preferably 0.1% to 4.0% and less, more preferably 0.5% to 3.5% and less, and even more preferably 1.0% to 3.0% and less. By ensuring that the apparent reflectivity of the orthogonal reflected light at the aforementioned angle of 5° is within the above-mentioned range, when observing an image in a state where the laminate for the display device of this embodiment is not bent, i.e., for example, when the angle θ2 in FIG12 is 180°, it is possible to suppress the observer's reflection into the display area, and to reduce the tonal difference between the images of one display area and another display area, thus suppressing tonal variations.

[0346] Here, the visual reflectance can be determined according to JIS Z8722:2009. Specifically, the method is the same as that described in "A. Laminate for Display Device 1. Characteristics of Laminate for Display Device" of the first embodiment above.

[0347] When light is incident at an angle of 60° onto the surface of the functional layer of a laminate for a display device, in order to reduce the perceived reflectivity of the positively reflected light, for example, (1-1) relatively reducing the refractive index of the functional layer, (1-2) making the functional layer a multilayer film with films having different refractive indices, and (1-3) adjusting the refractive index of the functional layer and the refractive index of the layer in contact with the substrate layer of the functional layer.

[0348] In the case of relatively reducing the refractive index of the functional layer as described in (1-1), by making the refractive index of the functional layer lower, the difference between the refractive index of the functional layer and the refractive index of air can be reduced, thereby suppressing the reflection of light on the surface of the functional layer of the laminate for the display device and reducing the perceived reflectivity of the positively reflected light at the incident angle of 60°. Methods for making the refractive index of the functional layer lower include, for example, containing a low-refractive-index inorganic material in the functional layer, or containing resin and low-refractive-index particles with a refractive index lower than that of the resin in the functional layer.

[0349] Furthermore, in the case where the functional layer is a multilayer film with layers of films having different refractive indices as described in (1-2), by making the functional layer a multilayer film with layers of films having different refractive indices, the reflection of light can be suppressed by light interference based on the thin film, and the apparent reflectivity of the positively reflected light at the incident angle of 60° can be reduced.

[0350] Furthermore, when adjusting the refractive index of the functional layer and the refractive index of the layer in contact with the substrate layer side of the functional layer as described in (1-3), by adjusting the refractive index of the functional layer and the refractive index of the layer in contact with the substrate layer side of the functional layer, light reflection can be suppressed by utilizing the light interference based on the thin film, thereby reducing the perceived reflectivity of the positively reflected light at an incident angle of 60°. In this case, the substrate layer can be an example of the layer in contact with the substrate layer side of the functional layer. Additionally, if a second functional layer is disposed between the substrate layer and the functional layer, the second functional layer can be a layer in contact with the substrate layer side of the functional layer. Furthermore, if a hard coating is disposed between the substrate layer and the functional layer, the hard coating group is a layer in contact with the substrate layer side of the general functional layer.

[0351] Furthermore, in this embodiment, after surface modification of the functional layer side of the laminate for display devices, a steel wool test is conducted where a specified load is applied to the functional layer side of the laminate for display devices using #0000 steel wool and subjected to 100 cycles of reciprocating friction. The maximum load that prevents peeling of the functional layer is 1.0 kg / cm². 2 The above, preferably, is 1.1 kg / cm² 2 The above, and more preferably, is 1.3 kg / cm². 2The above describes how, by setting the maximum load within the aforementioned range, warping at the bending point can be suppressed when the laminated body for the display device is repeatedly bent. Furthermore, the maximum load is preferably 2.0 kg / cm². 2 Below, 1.9kg / cm 2 The following is more preferably 1.7 kg / cm 2 the following.

[0352] By setting the maximum load within the aforementioned range, cracks or breakage at the bending points can be suppressed when the laminated body of the display device is repeatedly bent. The maximum load is preferably 1.0 kg / cm². 2 Above 2.0kg / cm 2 Below, 1.1kg / cm 2 Above 1.9kg / cm 2 The following is more preferably 1.3 kg / cm 2 Above 1.7kg / cm 2 the following.

[0353] It should be noted that in this embodiment, when conducting the steel wool test on the functional layer side of the laminate for display devices, the surface of the functional layer side of the laminate for display devices is modified before the steel wool test. This is because, regardless of the configuration of the laminate for display devices, the surface state of the functional layer side can be made consistent. By performing surface modification, a unified surface state with increased surface tension can be achieved, allowing for appropriate evaluation of the adhesion of functional layers with different surface states. Furthermore, according to the surface modification method, the effect of surface modification may weaken over time; therefore, it is preferable to perform the steel wool test immediately after surface modification of the laminate for display devices.

[0354] Here, corona discharge treatment can be cited as a method for surface modification. The specific conditions for corona discharge treatment are as follows.

[0355] Output voltage: 14kV

[0356] • Distance from the functional layer side of the laminate for display devices to the electrodes of the corona discharge treatment device: 2mm

[0357] • The moving speed of the worktable of the corona discharge treatment device: 30 mm / s

[0358] Alternatively, as a corona discharge treatment device, the "Corona Scanner ASA-4" manufactured by Shin-Kuang Electric Equipment Co., Ltd. can be used, for example.

[0359] Furthermore, surface modification methods can include surface treatments that reduce the contact angle between the functional layer side of the laminate used in the display device and water to 30° or more and 80° or less. Examples of such surface treatments include corona discharge treatment and plasma treatment.

[0360] It should be noted that the contact angle of the functional layer side of the laminate for display devices facing water can be determined using the θ / 2 method. Specifically, under conditions of 20°C and 50% RH, 2 μL of pure water is added dropwise to the functional layer side of the laminate for display devices, and the static contact angle after 5 seconds is calculated. For example, the fully automatic contact angle meter "DropMaster 700" manufactured by Kyowa Interface Science Co., Ltd. can be used as a contact angle meter.

[0361] Alternatively, the steel wool test can be conducted as follows: Using #0000 steel wool, fix the steel wool to a 1cm × 1cm clamp and apply a load of 100g / cm. 2 Under the conditions of a moving speed of 100 mm / s and a moving distance of 50 mm, the surface of the functional layer of the laminated material of the display device is rubbed back and forth 100 times. At this time, the load is increased from 100 g / cm². 2 Starting from per 100g / cm 2 Gradually increase the load to determine the maximum load that will not cause peeling of the functional layer. For the steel wool #0000, Bonstar #0000 manufactured by Japan Steel Wool Co., Ltd. can be used. For the testing machine, for example, the vibration-type friction fastness tester AB-301 manufactured by TESTERSANGYO Co., Ltd. It should be noted that, regarding the steel wool test, for example, a 5cm × 10cm display device is fixed to a glass plate with celluloid tape in a laminated state without creases or wrinkles, and the measurement is performed in this state.

[0362] When performing a prescribed steel wool test on the functional layer side of a laminate for a display device after surface modification, methods such as adjusting the hardness and adhesion of the functional layer can be employed to ensure that the maximum load preventing peeling of the functional layer is within a specified range. Methods for adjusting the hardness and adhesion of the functional layer include, for example, placing a second functional layer between the substrate layer and the functional layer, and adjusting the thickness of the functional layer. Furthermore, methods for adjusting the hardness and adhesion of the functional layer can include: placing a second functional layer between the substrate layer and the functional layer; adjusting the thickness of the functional layer; combining methods such as surface treatment of the layer in contact with the substrate layer side of the functional layer; and adjusting the material of the functional layer.

[0363] In the aforementioned method of configuring a second functional layer between the substrate layer and the functional layer, for example, when the substrate layer is a resin substrate and the functional layer is an inorganic film, although the hardness of the functional layer (inorganic film) is high, the adhesion between the functional layer (inorganic film) and the substrate layer (resin substrate) tends to decrease, and the maximum load tends to decrease. However, by configuring a second functional layer between the substrate layer and the functional layer, and making the second functional layer contain resin and inorganic particles, the adhesion of the functional layer can be improved compared to the above, and the maximum load can be increased to keep it within a specified range. Furthermore, for example, when the substrate layer is a glass substrate and the functional layer is an inorganic film, although the hardness of the functional layer (inorganic film) is high, the adhesion between the functional layer (inorganic film) and the substrate layer (glass substrate) tends to be excessively high, and the maximum load tends to become excessively large. However, by configuring a second functional layer between the substrate layer and the functional layer, and making the second functional layer contain resin and inorganic particles, the adhesion of the functional layer can be appropriately reduced compared to the above, and the maximum load can be appropriately reduced to keep it within a specified range.

[0364] Furthermore, when adjusting the thickness of the aforementioned functional layer, if the thickness of the functional layer is thin, the hardness of the functional layer decreases and the adhesion of the functional layer decreases; on the other hand, if the thickness of the functional layer is thick, the hardness of the functional layer increases and the adhesion of the functional layer tends to increase.

[0365] Furthermore, when the aforementioned method of surface-treating the layer in contact with the substrate layer side of the functional layer and the method of adjusting the material of the functional layer are combined, for example, adjusting the material of the functional layer can increase the hardness of the functional layer, and surface-treating the layer in contact with the substrate layer side of the functional layer can improve the adhesion of the functional layer, thereby increasing the maximum load within the specified range. In this case, the substrate layer can be an example of the layer in contact with the substrate layer side of the functional layer. Additionally, if a second functional layer is disposed between the substrate layer and the functional layer, the second functional layer can be a layer in contact with the substrate layer side of the functional layer. Furthermore, if a hard coating layer is disposed between the substrate layer and the functional layer, the hard coating layer can be a layer in contact with the substrate layer side of the functional layer.

[0366] Regarding the total light transmittance, haze, and bending resistance of the laminate for display devices in this embodiment, they are the same as those described in the "A. Laminate for Display Device 1. Characteristics of Laminate for Display Device" section of the first embodiment above, and therefore the description here is omitted.

[0367] 2. Functional layer

[0368] In this embodiment, the functional layer is a layer disposed on one side of the substrate layer.

[0369] In this embodiment, the functional layer functions as a low-reflection film. The functional layer can be a single layer or multiple layers. The following description will be divided into the case where the functional layer is a single layer and the case where it is a multiple layer.

[0370] (1) Case where the functional layer is a single layer

[0371] When the functional layer is a single layer, the refractive index of the functional layer is preferably, for example, 1.40 or higher and 1.50 or lower. Here, as described below, a resin substrate or a glass substrate can be used as the substrate layer, for example. The refractive index of common resins is about 1.5, and the refractive index of common glass is also about 1.5. By making the refractive index of the functional layer within the above range, the difference in refractive index with air can be reduced, and surface reflection of light from the functional layer side of the laminate for the display device can be suppressed. In addition, if the refractive index of the functional layer is within the above range, the difference in refractive index between the functional layer and the substrate layer can be increased, and surface reflection of light from the functional layer side can be suppressed through thin-film interference of the positively reflected light from the interface between the functional layer and the substrate layer and the positively reflected light from the surface of the functional layer side. Therefore, the perceived reflectivity of the positively reflected light at the incident angle of 60° can be reduced.

[0372] When the functional layer is a single layer, the refractive index of the functional layer is preferably 1.40 or higher, more preferably 1.43 or higher, and even more preferably 1.45 or higher. By setting the refractive index of the functional layer to the above range, the difference between the refractive index of the functional layer and the refractive index of the substrate layer, and the difference between the refractive index of the functional layer and the refractive index of the layer adjacent to the substrate layer side of the functional layer, can be increased, and light reflection can be suppressed by utilizing the light interference based on the thin film. Furthermore, when the functional layer is a single layer, the refractive index of the functional layer is preferably 1.50 or lower, more preferably 1.49 or lower, and even more preferably 1.48 or lower. By setting the refractive index of the functional layer to the above range, the difference in refractive index with air can be reduced, and light reflection from the functional layer side of the laminate for the display device can be suppressed. When the functional layer is a single layer, the refractive index of the functional layer is preferably 1.40 or higher and 1.50 or lower, more preferably 1.43 or higher and 1.49 or lower, and even more preferably 1.45 or higher and 1.48 or lower.

[0373] Here, the refractive index of each layer refers to the refractive index relative to light with a wavelength of 550 nm. One method for measuring the refractive index is using an ellipsometer. Examples of ellipsometers include the "UVSEL" manufactured by Jobin Yvon and the "DF1030R" manufactured by Techno Synergy.

[0374] Furthermore, the thickness of the functional layer is appropriately adjusted according to the refractive index of the functional layer. When the functional layer is a single layer, the thickness is preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 70 nm or more. If the thickness of the functional layer is too thin, the hardness and adhesion of the functional layer decrease, and the maximum load without peeling during the steel wool test after the surface modification becomes too small, potentially causing warping at the bent portion during repeated bending. Additionally, when the functional layer is a single layer, the thickness is preferably 140 nm or less, more preferably 130 nm or less, and even more preferably 120 nm or less. If the thickness of the functional layer is too thick, the adhesion becomes excessive, and the maximum load without peeling during the steel wool test after the surface modification becomes too large, potentially causing cracks or breakage at the bent portion during repeated bending. When the functional layer is a single layer, the thickness is preferably 50 nm or more and 140 nm or less, more preferably 60 nm or more and 130 nm or less, and even more preferably 70 nm or more and 120 nm or less.

[0375] Here, the thickness of the functional layer is measured using a cross-section along the thickness direction of the laminate used in the display device, observed with a transmission electron microscope (TEM), scanning electron microscope (SEM), or scanning transmission electron microscope (STEM). This value can be the average thickness of 10 randomly selected locations. It should be noted that the method for measuring the thickness of other layers in the laminate used in the display device can also be the same.

[0376] The material used for the functional layer is not particularly limited, as long as it meets the maximum load required to prevent peeling during the steel wool test after the surface modification and satisfies the aforementioned refractive index. The functional layer can be, for example, either an inorganic film or an organic-inorganic hybrid film. If the functional layer is an inorganic film, it may contain, for example, a low-refractive-index inorganic material having the aforementioned refractive index. Alternatively, if the functional layer is an organic-inorganic hybrid film, it may contain, for example, a resin and low-refractive-index particles with a refractive index lower than that of the resin.

[0377] The functional layer is preferably an inorganic membrane. Compared with organic-inorganic hybrid membranes and organic membranes, inorganic membranes tend to have higher hardness, making it easier to obtain a functional layer that meets the maximum load requirement of not peeling off during the steel wool test after the above surface modification.

[0378] When the functional layer contains a low-refractive-index inorganic material, there are no particular limitations on the type of inorganic material, as long as the functional layer composed of the low-refractive-index inorganic material can meet the maximum load that prevents the functional layer from peeling off during the steel wool test after the above-mentioned surface modification, and the inorganic material meets the above-mentioned refractive index. Examples include silica, magnesium fluoride, lithium fluoride, calcium fluoride, and barium fluoride. Silica is preferred among these.

[0379] Furthermore, when the functional layer contains resin and low-refractive-index particles, there are no particular limitations on the low-refractive-index particles, as long as they have a refractive index lower than that of the resin and can satisfy the aforementioned refractive index.

[0380] The low-refractive-index particles can be either inorganic or organic. Examples of inorganic particles include silicon dioxide, magnesium fluoride, lithium fluoride, calcium fluoride, and barium fluoride. Silicon dioxide particles are preferred.

[0381] Furthermore, the low-refractive-index particles can be any of the following: solid particles, hollow particles, or porous particles. Among these, hollow particles and porous particles are preferred due to their low refractive index. Examples of hollow particles and porous particles include porous silica particles, hollow silica particles, porous polymer particles, and hollow polymer particles.

[0382] In addition, low-refractive-index particles can be surface-treated. By performing surface treatment on low-refractive-index particles, their affinity with resins and solvents is improved, the dispersion of low-refractive-index particles becomes more uniform, and the low-refractive-index particles are less likely to aggregate. Therefore, it is possible to suppress the reduction of transparency of the functional layer, the coatability of the resin composition for the functional layer, and the reduction of film strength.

[0383] As a surface treatment method, examples include surface treatment using silane coupling agents. Regarding specific silane coupling agents, the same silane coupling agent disclosed in Japanese Patent Application Publication No. 2013-142817 may be used.

[0384] Furthermore, low-refractive-index particles can be reactive particles with polymerizable functional groups on their surface. Examples of low-refractive-index particles as reactive particles include those used in low-refractive-index layers as described in Japanese Patent Application Publication No. 2013-142817.

[0385] The average particle size of the low-refractive-index particles can be less than or equal to the thickness of the functional layer, for example, less than 200 nm or less than 100 nm. Alternatively, the average particle size can be greater than or equal to 5 nm, 10 nm, 30 nm, or 50 nm. If the average particle size is within the above range, a good dispersion of the low-refractive-index particles can be achieved without compromising the transparency of the functional layer. It should be noted that if the average particle size is within the above range, the average particle size can be either a primary or secondary particle size, and the low-refractive-index particles can also be linked in chains.

[0386] Here, the average particle size of the low-refractive-index particles refers to the average of 20 particles observed through a transmission electron microscope (TEM) photograph of the cross-section of the functional layer.

[0387] The shape of low refractive index particles is not particularly limited; for example, spherical, chain-like, and needle-like shapes can be included.

[0388] Furthermore, when the functional layer contains resin and low-refractive-index particles, there is no particular limitation on the resin as long as it can provide a functional layer with a maximum load that prevents peeling during the steel wool test after the aforementioned surface modification. A cured resin that is cured by irradiation with heat or ionizing radiation such as ultraviolet light or electron beams is preferred. Examples of cured resins include thermosetting resins and ionizing radiation-cured resins. Examples of ionizing radiation-cured resins include ultraviolet-cured resins and electron beam-cured resins. Ionizing radiation-cured resins are preferred because they can improve the surface hardness of the functional layer.

[0389] Here, "ionizing ray cured resin" in this specification refers to resin that has been cured by irradiation with ionizing rays. In addition, "ionizing rays" refers to energy quanta in electromagnetic waves or charged ion beams that can cause molecules to polymerize or cross-link. Examples include electromagnetic waves such as X-rays and gamma rays, as well as charged ion beams such as alpha rays and ion beams, in addition to ultraviolet rays and electron beams.

[0390] Examples of ionizing radiation-curable resins include compounds with one or more unsaturated bonds, such as compounds having acrylate functional groups. Examples of compounds with one unsaturated bond include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone. Examples of compounds with two or more unsaturated bonds include polyfunctional compounds such as polymethylolpropane tri(meth)acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate, as well as reaction products of the above polyfunctional compounds with (meth)acrylates (e.g., poly(meth)acrylates of polyols). Furthermore, "(meth)acrylate" refers to both methacrylates and acrylates.

[0391] In addition, as the aforementioned ionizing ray curable resin, low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol-polyene resins, etc., having unsaturated double bonds can also be used. Furthermore, low refractive index resins described later can also be used as the resin.

[0392] The content of resin and low refractive index particles in the functional layer is appropriately set in such a way that the functional layer does not produce the maximum load of peeling when the steel wool test is performed after the above surface modification, and the refractive index of the functional layer as a whole meets the above refractive index.

[0393] When using a UV-curable resin as the resin, the functional layer may also contain a photopolymerization initiator. Furthermore, when the functional layer contains both resin and low-refractive-index particles, various additives can be included depending on the desired physical properties. Examples of additives include, for instance, UV absorbers, antioxidants, light stabilizers, infrared absorbers, dispersants, weather resistance improvers, abrasion resistance improvers, antistatic agents, polymerization inhibitors, crosslinking agents, adhesion improvers, leveling agents, thixotropic agents, coupling agents, plasticizers, defoamers, and fillers.

[0394] The method for forming the functional layer is appropriately selected based on the material of the functional layer. When the functional layer contains a low-refractive-index inorganic material, methods for forming the functional layer include, for example, vacuum evaporation and sputtering. Furthermore, when the functional layer contains resin and low-refractive-index particles, methods for forming the functional layer include, for example, coating a resin composition for the functional layer onto a substrate layer and then curing it.

[0395] (2) Cases where there are multiple functional layers

[0396] When there are multiple functional layers, the functional layers may, for example, sequentially have a high refractive index film and a low refractive index film from the substrate layer side, or have a low refractive index film, a high refractive index film and a low refractive index film, or have a high refractive index film, a low refractive index film, a high refractive index film and a low refractive index film.

[0397] When the functional layer is multi-layered, the number of layers can be two or more, with two layers being preferred. If the number of layers increases, the thickness and hardness of the functional layer will increase, and the maximum load at which the functional layer does not peel off during the steel wool test after the above surface modification may become too large.

[0398] Furthermore, when the functional layer is multilayered, the outermost surface of the functional layer typically has a low-refractive-index film on the side opposite to the substrate layer. The refractive index of the low-refractive-index film can be the same as that of the functional layer when it is a single layer.

[0399] Furthermore, when the functional layer has multiple layers, and the functional layer includes both a low-refractive-index film and a high-refractive-index film, the refractive index of the high-refractive-index film only needs to be higher than that of the low-refractive-index film. For example, it is preferably 1.55 to 3.00, more preferably 1.60 to 2.50, and even more preferably 1.65 to 2.00. If the refractive index of the high-refractive-index film is within the above range, the reflectivity can be easily adjusted by adjusting the refractive index and thickness of each layer constituting the functional layer.

[0400] Furthermore, when the functional layer is multi-layered, the thickness of the functional layer is preferably 70 nm or more, more preferably 80 nm or more, and even more preferably 90 nm or more. If the thickness of the functional layer is too thin, the hardness and adhesion of the functional layer decrease, and the maximum load that prevents the functional layer from peeling during the steel wool test after the above surface modification becomes too small, and warping may occur at the bending point during repeated bending. Additionally, the thickness of the functional layer is preferably 140 nm or less, more preferably 130 nm or less, and even more preferably 120 nm or less. If the thickness of the functional layer is too thick, the adhesion of the functional layer is excessive, and the maximum load that prevents the functional layer from peeling during the steel wool test after the above surface modification becomes too large, and cracks or breakage may occur at the bending point during repeated bending. When the functional layer is multi-layered, the thickness of the functional layer is preferably 70 nm or more and 140 nm or less, more preferably 80 nm or more and 130 nm or less, and even more preferably 90 nm or more and 120 nm or less.

[0401] It should be noted that when there are multiple functional layers, the thickness of the aforementioned functional layer refers to the overall thickness of the functional layer.

[0402] The thickness of each film constituting the functional layer is appropriately adjusted according to the refractive index of each film.

[0403] The thickness of the low-refractive-index film is preferably 5 nm to 140 nm, more preferably 20 nm to 130 nm, and even more preferably 40 nm to 120 nm. If the low-refractive-index film is too thin, the hardness and adhesion of the functional layer decrease, and the maximum load that prevents the functional layer from peeling during the steel wool test after the above surface modification becomes too small, and warping may occur at the bending point during repeated bending. On the other hand, if the thickness of the low-refractive-index film is too thick, the adhesion of the functional layer is excessive, and the maximum load that prevents the functional layer from peeling during the steel wool test after the above surface modification becomes too large, and cracks or breaks may occur at the bending point during repeated bending.

[0404] The thickness of the high refractive index film is preferably 5 nm to 140 nm, more preferably 20 nm to 130 nm, and even more preferably 40 nm to 120 nm. If the high refractive index film is too thin, the hardness and adhesion of the functional layer decrease, and the maximum load that prevents the functional layer from peeling during the steel wool test after the above surface modification becomes too small, and warping may occur at the bending point during repeated bending. If the thickness of the high refractive index film is too thick, the adhesion of the functional layer is excessive, and the maximum load that prevents the functional layer from peeling during the steel wool test after the above surface modification becomes too large, and cracks or breaks may occur at the bending point during repeated bending.

[0405] As for the material of the low refractive index film, there are no particular limitations as long as it is a material that can provide a functional layer that does not peel off during the steel wool test after the above surface modification and that provides a low refractive index film that meets the above refractive index. The low refractive index film can be, for example, either an inorganic film or an organic-inorganic hybrid film.

[0406] When the low-refractive-index film is an inorganic film, it may contain, for example, a low-refractive-index inorganic material having the aforementioned refractive index. Furthermore, when the low-refractive-index film is an organic-inorganic hybrid film or an organic film, it may contain, for example, a resin and low-refractive-index particles with a refractive index lower than that of the resin.

[0407] Among them, the low refractive index film is preferably an inorganic film. Compared with organic-inorganic hybrid films and organic films, inorganic films tend to have higher hardness, making it easier to obtain a functional layer that meets the maximum load requirement of not peeling off during the steel wool test after the above surface modification.

[0408] When a low-refractive-index film contains a low-refractive-index inorganic material, the low-refractive-index inorganic material can be the same as the low-refractive-index inorganic material used when the functional layer is a single layer and is an inorganic film.

[0409] Furthermore, when the low-refractive-index film contains resin and low-refractive-index particles, the resin and low-refractive-index particles used are the same as those used in the cases where the functional layer is a single layer and an organic-inorganic mixed film, respectively.

[0410] There are no particular limitations on the material used for high refractive index films, as long as it is a material that can provide a functional layer that does not experience peeling during the steel wool test after the aforementioned surface modification and that provides a high refractive index film that meets the aforementioned refractive index. For example, a high refractive index film can be either an inorganic film or an organic-inorganic hybrid film.

[0411] When the high-refractive-index film is an inorganic film, it may contain, for example, a high-refractive-index inorganic material having the aforementioned refractive index. Alternatively, when the high-refractive-index film is an organic-inorganic hybrid film, it may contain, for example, a resin and high-refractive-index particles with a refractive index higher than that of the resin.

[0412] When a high refractive index film contains high refractive index inorganic materials, there are no particular limitations on the inorganic materials used as high refractive index inorganic materials, as long as the high refractive index film composed of high refractive index inorganic materials can meet the above-mentioned refractive index. Examples include zirconium oxide, silicon monoxide, hafnium oxide, tantalum oxide, niobium oxide, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, magnesium oxide, yttrium oxide, lanthanum fluoride, and cerium fluoride.

[0413] Furthermore, when a high-refractive-index film contains both resin and high-refractive-index particles, there are no particular limitations on the high-refractive-index particles, as long as they have a higher refractive index than the resin and a high-refractive-index film satisfying the aforementioned refractive index can be obtained. The high-refractive-index particles can be either inorganic or organic particles. Examples of inorganic particles include zirconium oxide, silicon monoxide, hafnium oxide, tantalum oxide, niobium oxide, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, magnesium oxide, yttrium oxide, lanthanum fluoride, and cerium fluoride.

[0414] The average particle size of the high refractive index particles can be less than or equal to the average particle size of the low refractive index particles.

[0415] There are no particular limitations on the shape of high refractive index particles; for example, they can be spherical, chain-like, or needle-like.

[0416] Furthermore, when the high refractive index film contains resin and high refractive index particles, the resin used can be the same as the resin used in the case where the functional layer is a single layer or an organic-inorganic mixed film.

[0417] The content of resin and high refractive index particles in the high refractive index film is appropriately set in such a way that the functional layer does not experience the maximum load required to peel off during the steel wool test after the above surface modification, and the refractive index of the functional layer as a whole meets the above refractive index.

[0418] When using a UV-curable resin as the resin, both low-refractive-index and high-refractive-index films may contain a photopolymerization initiator. Furthermore, when a low-refractive-index film contains resin and low-refractive-index particles, or a high-refractive-index film contains resin and high-refractive-index particles, various additives may be included depending on the desired physical properties. These additives can be the same as those used when the functional layer is a single layer.

[0419] The methods for forming low-refractive-index films and high-refractive-index films can be appropriately selected based on the materials of the low-refractive-index film and the high-refractive-index film. Furthermore, when the low-refractive-index film contains low-refractive-index inorganic materials, and the high-refractive-index film contains high-refractive-index inorganic materials, methods for forming the low-refractive-index film and the high-refractive-index film can include, for example, coating a low-refractive-index film resin composition or a high-refractive-index film resin composition onto a substrate layer and then curing it.

[0420] 3. Second functional layer

[0421] Regarding the laminate for the display device in this embodiment, as shown in FIG13, it is preferable to have a second functional layer 44 between the substrate layer 42 and the functional layer 43. By distributing the second functional layer between the substrate layer and the functional layer, the adhesion of the functional layer can be adjusted, and the maximum load at which the functional layer does not peel off during the steel wool test after the above-mentioned surface modification can be controlled.

[0422] The refractive index of the second functional layer is preferably 1.55 to 2.00, more preferably 1.60 to 1.90, and even more preferably 1.65 to 1.80. If the refractive index of the second functional layer is within the above range, the reflectivity can be easily adjusted by adjusting the refractive index and thickness of the functional layer and the second functional layer. However, if the refractive index of the second functional layer is too small, the difference between the refractive index of the second functional layer and the refractive index of the functional layer decreases, which may prevent the effective suppression of light reflection using thin-film-based light interference from being fully achieved.

[0423] Furthermore, the thickness of the second functional layer is preferably 50 nm to 10 μm, more preferably 60 nm to 7 μm, and even more preferably 70 nm to 5 μm. By keeping the thickness of the second functional layer within the above range, the adhesion to the functional layer can be adjusted without compromising flexibility and bending resistance. However, if the thickness of the second functional layer is too thick, flexibility and bending resistance may be compromised.

[0424] When the aforementioned functional layer is an inorganic film, the second functional layer is preferably an organic-inorganic hybrid film. For example, when the substrate layer is a resin substrate and the functional layer is an inorganic film, although the functional layer (inorganic film) has high hardness, the adhesion between the functional layer (inorganic film) and the substrate layer (resin substrate) tends to decrease, and the aforementioned maximum load tends to decrease. However, by distributing a second functional layer between the substrate layer and the functional layer, and making the second functional layer an organic-inorganic hybrid film, the adhesion of the functional layer can be improved compared to the above, and the aforementioned maximum load can be increased and kept within a specified range. Furthermore, for example, when the substrate layer is a glass substrate and the functional layer is an inorganic film, although the functional layer (inorganic film) has high hardness, the adhesion between the functional layer (inorganic film) and the substrate layer (glass substrate) tends to become too high, and the aforementioned maximum load tends to become too large. However, by distributing a second functional layer between the substrate layer and the functional layer, and making the second functional layer an organic-inorganic hybrid film, the adhesion of the functional layer can be appropriately reduced compared to the above, and the aforementioned maximum load can be appropriately reduced and kept within a specified range.

[0425] In the case where the second functional layer is an organic-inorganic hybrid membrane, the second functional layer may contain resin and inorganic particles.

[0426] When the second functional layer contains resin and inorganic particles, there are no particular limitations on the inorganic particles, as long as a second functional layer with the aforementioned refractive index can be obtained. Examples of inorganic particles include high-refractive-index particles such as zirconium oxide, silicon monoxide, hafnium oxide, tantalum oxide, niobium oxide, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, magnesium oxide, yttrium oxide, lanthanum fluoride, and cerium fluoride, as well as low-refractive-index particles such as silicon dioxide, magnesium fluoride, lithium fluoride, calcium fluoride, and barium fluoride. Among these, zirconium oxide is preferred as a high-refractive-index particle, and silicon dioxide is preferred as a low-refractive-index particle.

[0427] Furthermore, the inorganic particles can undergo surface treatment. By surface treating the inorganic particles, their affinity with resins and solvents is improved, the dispersion of the inorganic particles becomes more uniform, and the inorganic particles are less prone to aggregation. Therefore, it is possible to suppress the decrease in transparency of the second functional layer, the coatability of the resin composition for the second functional layer, and the decrease in film strength. The surface treatment method can be the same as the surface treatment method used for the low-refractive-index particles used in the aforementioned functional layers.

[0428] In addition, inorganic particles can be reactive particles with polymerizable functional groups on their surface.

[0429] The average particle size of the inorganic particles can be less than or equal to the thickness of the second functional layer; for example, it can be less than 300 nm, less than 200 nm, less than 150 nm, or less than 100 nm. Alternatively, the average particle size can be 5 nm or more, 10 nm or more, 30 nm or more, or 50 nm or more. If the average particle size of the inorganic particles is within the above range, a good dispersion of the inorganic particles can be obtained without compromising the transparency of the second functional layer. It should be noted that if the average particle size of the inorganic particles is within the above range, the average particle size can be either a primary particle size or a secondary particle size, and the inorganic particles can also be chained together. It should also be noted that the method for determining the average particle size of the inorganic particles can be the same as the method for determining the average particle size of the low-refractive-index particles used in the functional layer described above.

[0430] The shape of inorganic particles is not particularly limited; for example, they can be spherical, chain-like, or needle-like.

[0431] In addition, if the second functional layer contains resin and inorganic particles, the resin can be the same as the resin used in the functional layer described above.

[0432] The content of resin and inorganic particles in the second functional layer is appropriately set in such a way that the functional layer does not produce the maximum load of peeling when the steel wool test is performed after the above surface modification, and the refractive index of the second functional layer as a whole meets the above refractive index.

[0433] When using a UV-curable resin as the resin, the second functional layer may also contain a photopolymerization initiator. Furthermore, when the second functional layer contains both resin and inorganic particles, various additives may be included depending on the desired physical properties. These additives may be the same as those used in the functional layers described above.

[0434] Furthermore, the surface of the second functional layer preferably undergoes surface treatment. This improves the adhesion between the second functional layer and the aforementioned functional layer, and appropriately increases the maximum load at which the functional layer does not peel off during the steel wool test after the surface modification.

[0435] As for surface treatment methods, there are no particular limitations as long as they can improve the adhesion between the second functional layer and the aforementioned functional layers. Examples include corona discharge treatment, plasma treatment, ozone treatment, glow discharge treatment, and oxidation treatment.

[0436] The surface treatment conditions are appropriately set to meet the maximum load required to prevent the functional layer from peeling during the steel wool test after surface modification. For example, if the output is too low, the adhesion between the second functional layer and the aforementioned functional layer will be insufficient, and the maximum load required to prevent peeling during the steel wool test after surface modification will be too low, potentially causing warping at the bend during repeated bending. Conversely, if the output is too high, the adhesion between the second functional layer and the aforementioned functional layer will be excessive, and the maximum load required to prevent peeling during the steel wool test after surface modification will be too high, potentially causing cracks or breakage at the bend during repeated bending. Furthermore, for example, if the surface treatment time is too short, the adhesion between the second functional layer and the aforementioned functional layer will be insufficient, and the maximum load required to prevent peeling during the steel wool test after surface modification will be too low, potentially causing warping at the bend during repeated bending. In addition, if the surface treatment time is too long, the adhesion between the second functional layer and the above functional layer will be too strong. When the steel wool test is carried out after the surface modification, the maximum load that prevents the functional layer from peeling will become too large. Cracks or breaks may occur at the bending part when repeatedly bent.

[0437] The method for forming the second functional layer is appropriately selected based on the material of the functional layer. When the second functional layer contains resin and inorganic particles, a possible method for forming the second functional layer is, for example, coating a resin composition for the second functional layer onto a substrate layer and then curing it.

[0438] 4. Substrate layer

[0439] In this embodiment, the substrate layer supports the aforementioned functional layer and is a transparent component.

[0440] As a substrate layer, there are no particular limitations as long as it is transparent; examples include resin substrates and glass substrates.

[0441] The details of the resin substrate and glass substrate used in this embodiment are the same as those described in "A. Laminate 3. Substrate Layer" of the first embodiment above, so the description here is omitted.

[0442] There is no particular limitation on the thickness of the substrate layer, as long as it is flexible, and it can be appropriately selected according to the type of substrate layer.

[0443] The thickness of the resin substrate is preferably 10 μm or more and 100 μm or less, more preferably 25 μm or more and 80 μm or less. By making the thickness of the resin substrate within the above range, good flexibility and sufficient hardness can be obtained. In addition, curling of the laminate for the display device can be suppressed. Furthermore, it is preferable to achieve lightweighting of the laminate for the display device.

[0444] The thickness of the glass substrate is preferably 200 μm or less, more preferably 15 μm or more and 100 μm or less, even more preferably 20 μm or more and 90 μm or less, and particularly preferably 25 μm or more and 80 μm or less. By making the thickness of the glass substrate within the above range, good flexibility and sufficient hardness can be obtained. In addition, curling of the laminate for the display device can be suppressed. Furthermore, it is preferable to achieve lightweighting of the laminate for the display device.

[0445] 5. Other layers

[0446] In the laminate for the display device in this embodiment, in addition to the substrate layer and the functional layer described above, other layers may also be present.

[0447] (1) Hard coating

[0448] The laminate for the display device in this embodiment may have a hard coating layer between the substrate layer and the functional layer. As described above, when a second functional layer is disposed between the substrate layer and the functional layer, for example, as shown in FIG. 14, a hard coating layer 45 may be disposed between the substrate layer 42 and the second functional layer 44. The hard coating layer is a component used to improve surface hardness. By disposing of a hard coating layer, scratch resistance can be improved. In particular, when the substrate layer is a resin substrate, scratch resistance can be effectively improved by disposing of a hard coating layer.

[0449] The refractive index of the hard coating is preferably 1.70 or less, more preferably 1.45 or more and 1.67 or less, even more preferably 1.48 or more and 1.65 or less, and particularly preferably 1.50 or more and 1.60 or less. By making the refractive index of the hard coating within the above range, the surface hardness can be improved without compromising flexibility and bending resistance.

[0450] The details of the material of the above-mentioned hard coating are the same as those described in "A. Laminate for display device 4. Other layers (1) Hard coating" of the first embodiment above, so the description here is omitted.

[0451] As a method for forming a hard coating, for example, a method of applying a resin composition for a hard coating onto the aforementioned substrate layer and then curing it can be described.

[0452] (2) Impact Absorption Layer

[0453] For example, as shown in FIG15, the laminate for the display device in this embodiment may have an impact-absorbing layer 46 on the side of the substrate layer 42 opposite to the functional layer 43. By configuring the impact-absorbing layer, the impact can be absorbed when an impact is applied to the laminate for the display device, thereby improving its impact resistance. In addition, when the substrate layer is a glass substrate, the breakage of the glass substrate can be suppressed.

[0454] The details of the shock-absorbing layer are the same as those described in “A. Laminates for display devices 4. Other layers (2) Shock-absorbing layer”, so the description here is omitted.

[0455] (3) Apply adhesive layer

[0456] For example, as shown in FIG16, the display device laminate in this embodiment may have an adhesive layer 47 for attachment on the side of the substrate layer 42 opposite to the functional layer 43. With the help of the adhesive layer for attachment, the display device laminate can be attached to, for example, a display panel.

[0457] As for the adhesive used in the bonding layer, there are no particular limitations as long as the adhesive is transparent and can be used to bond the display device to the display panel in a laminate. Examples include thermosetting adhesives, UV-curing adhesives, two-component curing adhesives, hot melt adhesives, pressure-sensitive adhesives (so-called adhesives), etc.

[0458] The thickness of the adhesive layer for attachment is preferably 10 μm to 100 μm, more preferably 25 μm to 80 μm, and even more preferably 40 μm to 60 μm. If the thickness of the adhesive layer for attachment is too thin, the laminate for the display device may not be able to bond sufficiently to the display panel, etc. In addition, if the thickness of the adhesive layer for attachment is too thick, flexibility may be compromised.

[0459] As an adhesive layer for attachment, an adhesive film can be used, for example. Alternatively, an adhesive composition can be applied to a support or substrate layer to form an adhesive layer for attachment.

[0460] (4) Anti-fouling layer

[0461] For example, as shown in FIG17, in this embodiment, the laminate for the display device may have an anti-fouling layer 48 on the side of the functional layer 43 opposite to the substrate layer 42. By configuring the anti-fouling layer, the laminate for the display device can be given anti-fouling properties. It should be noted that, in this embodiment, since the thickness of the anti-fouling layer is relatively thin as described below, it is presumed that it will not affect thin-film interference.

[0462] As the material for the anti-fouling layer, common anti-fouling layer materials can be used. Specifically, since the content is the same as that described in "A. Laminates for display devices 4. Other layers (4) Anti-fouling layer", the description here is omitted.

[0463] The thickness of the antifouling layer is preferably 1 nm to 30 nm, more preferably 2 nm to 20 nm, and even more preferably 3 nm to 10 nm. If the thickness of the antifouling layer is within the above range, good antifouling properties and durability can be achieved.

[0464] Examples of methods for forming an antifouling layer include coating an antifouling resin composition onto the aforementioned functional layer and curing it, vacuum evaporation, and sputtering.

[0465] (5) Interlayer adhesive layer

[0466] In the laminated body for display device in this embodiment, interlayer adhesive layers can be disposed between each layer.

[0467] The adhesive used in the interlayer bonding layer can be the same as the adhesive used in the bonding layer described above.

[0468] The thickness and formation method of the interlayer adhesive layer can be the same as those of the adhesive layer used for attachment described above.

[0469] 6. Applications of laminates for display devices

[0470] The laminate for display devices in this embodiment can be used as a front panel in a display device, positioned closer to the viewer than the display panel. Specifically, the laminate for display devices in this embodiment can be appropriately used as the front panel in flexible display devices such as foldable displays, rollable displays, and bendable displays. In particular, the laminate for display devices in this embodiment improves the visibility of the bent portion and the visibility in a usage mode where the image is viewed while the display device is bent, thus making it suitable for use as the front panel in foldable displays.

[0471] In addition, the display device laminate in this embodiment can be used, for example, in the front panel of display devices such as smartphones, tablet terminals, wearable terminals, personal computers, televisions, digital signage, public information displays (PIDs), and vehicle displays.

[0472] B. Display device

[0473] The display device in this embodiment includes: a display panel; and a display device laminate disposed on the observer side of the display panel.

[0474] Figure 18 is a schematic cross-sectional view showing an example of the display device in this embodiment. As shown in Figure 18, the display device 30 includes a display panel 31 and a display device laminate 41 disposed on the observer side of the display panel 31. In the display device 30, the display device laminate 41 and the display panel 31 can be bonded together, for example, by means of an adhesive layer 47 for attaching the display device laminate 41.

[0475] When the display device in this embodiment is disposed on the surface of the display device using a laminate, it is disposed with the functional layer on the outside and the substrate layer on the inside.

[0476] There are no particular limitations on the method of arranging the display device in this embodiment on the surface of the display device using a laminate, for example, a method using an adhesive layer can be cited.

[0477] As the display panel in this embodiment, examples include display panels used in display devices such as organic EL display devices and liquid crystal display devices.

[0478] The display device in this embodiment may have a touch panel component between the display panel and the display device laminate.

[0479] The display device in this embodiment is preferably a flexible display device such as a foldable display screen, a rollable display screen, or a bendable display screen.

[0480] Furthermore, the display device in this embodiment is preferably foldable. That is, the display device in this embodiment is preferably a foldable display screen. In the display device of this embodiment, the visibility of the curved portion and the visibility in the usage mode of observing the image with the display device bent are excellent, making it suitable as a foldable display screen.

[0481] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are illustrative examples, and any solution that has the same structure and performs the same effect as the technical concept described in the claims of this disclosure is included within the technical scope of this disclosure.

[0482] Example

[0483] The following description is divided into two embodiments: the first embodiment and the second embodiment, which respectively illustrate the examples and comparative examples to further explain this disclosure.

[0484] I. Examples of the first embodiment

[0485] The following describes Examples 1 to 18 of the first embodiment and Comparative Examples 1 to 8.

[0486] [Example 1]

[0487] (1) Formation of the first layer

[0488] First, the components are mixed in the manner shown below to obtain resin composition 1 for functional layer.

[0489] <Composition of Resin Composition 1 for Functional Layers>

[0490] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0491] • Carbamate acrylate (product name "8UX-047A", manufactured by Taisei Fine Chemicals): 85 parts by weight

[0492] • Pentaerythritol tetraacrylate (product name "ATM-4E", manufactured by Shin-Nakamura Chemical Co., Ltd.): 15 parts by weight

[0493] Methyl isobutyl ketone: 200 parts by weight

[0494] Next, as the substrate layer, a 50 μm thick polyimide film (Neoprim manufactured by Mitsubishi Gas Chemical Co., Ltd.) was coated onto the substrate layer using a doctor blade coater to form the aforementioned functional layer resin composition 1. Afterwards, the coating film was heated to 70°C for 1 minute to evaporate the solvent, and then irradiated with ultraviolet light (FusionUV Systems Japan, H-bulb light source) at an oxygen concentration of 200 ppm and a cumulative light intensity of 40 mJ / cm². 2 The coating is cured by irradiating it with ultraviolet light, forming the first layer with a thickness of 3μm.

[0495] (2) Formation of the second layer

[0496] First, the components are mixed in the manner shown below to obtain resin composition 2 for functional layer.

[0497] <Composition of Resin Composition 2 for Functional Layers>

[0498] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0499] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 72 parts by weight

[0500] • Multifunctional acrylate (product name "M-510", manufactured by Dong-A Synthetic Co., Ltd.): 28 parts by weight

[0501] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 70 parts by weight (100% solids conversion).

[0502] Methyl isobutyl ketone: 220 parts by weight

[0503] Next, the functional layer resin composition 2 is applied to the first layer using a doctor blade coater to form a coating film. Then, the coating film is heated to 70°C for 1 minute to evaporate the solvent, and then irradiated with ultraviolet light (using an H-bulb light source manufactured by Fusion UV Systems Japan) at an oxygen concentration of less than 200 ppm and a cumulative light intensity of 400 mJ / cm². 2 The coating is cured by irradiating it with ultraviolet light to form a second layer with a thickness of 3μm.

[0504] (3) Formation of antifouling layer

[0505] The surface of the second layer was modified by plasma treatment at an output of 200W for 1 minute.

[0506] Subsequently, a fluorine compound (manufactured by Daikin Industries, Ltd., product name "OPTOOL UD120") was deposited on the surface-modified second layer using a vacuum evaporation apparatus (manufactured by ULVAC) to form an antifouling layer with a thickness of 7 nm.

[0507] [Example 2]

[0508] Except that the thickness of the second layer is 10 μm, the laminate is fabricated in the same manner as in Example 1.

[0509] [Example 3]

[0510] The second layer is formed using the following functional layer resin composition 3, and the laminate is otherwise made in the same manner as in Example 1.

[0511] <Composition of Resin Composition 3 for Functional Layers>

[0512] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0513] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 63 parts by weight

[0514] • Multifunctional acrylate (product name "M-510", manufactured by Dong-A Synthetic Co., Ltd.): 37 parts by weight

[0515] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 130 parts by weight (100% solids conversion).

[0516] Methyl isobutyl ketone: 220 parts by weight

[0517] [Example 4]

[0518] The first layer is formed using the following functional layer resin composition 4, and the laminate is otherwise made in the same manner as in Example 1.

[0519] <Composition of Resin Composition 4 for Functional Layers>

[0520] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0521] • Carbamate acrylate (product name "8UX-047A", manufactured by Taisei Fine Chemicals): 89 parts by weight

[0522] • Pentaerythritol tetraacrylate (product name "ATM-4E", manufactured by Shin-Nakamura Chemical Co., Ltd.): 11 parts by weight

[0523] • High refractive index particles (zirconia, average primary particle size 20 nm, manufactured by CIK Nano Tek): 170 parts by weight (100% solids conversion).

[0524] Methyl isobutyl ketone: 240 parts by weight

[0525] [Example 5]

[0526] An example of a substrate layer that also serves as the first layer. As the substrate layer that also serves as the first layer, a 50 μm thick polyimide film ("Neoprim" manufactured by Mitsubishi Gas Chemical Co., Ltd.) is used.

[0527] The surface of the first layer was modified by plasma treatment at an output of 300W for 2 minutes.

[0528] Subsequently, a second layer with a thickness of 90 nm was formed by vacuum evaporation on the first layer after surface modification using a vacuum evaporation apparatus (manufactured by ULVAC).

[0529] Next, an antifouling layer is formed on the second layer as in Example 1 to create a laminate.

[0530] [Example 6]

[0531] An example of a substrate layer that also serves as the first layer. As the substrate layer that also serves as the first layer, a polyamide film ("Mictron" manufactured by Toray Industries, Inc.) with a thickness of 30 μm was used, and the laminate was otherwise fabricated in the same manner as in Example 5.

[0532] [Example 7]

[0533] (1) Formation of the first layer

[0534] The first layer is formed on the substrate layer in the same manner as in Example 1.

[0535] (2) Formation of the second layer

[0536] A second layer is formed on the first layer as in Example 5.

[0537] (3) Formation of antifouling layer

[0538] Similar to Example 1, an antifouling layer is formed on the second layer described above.

[0539] [Example 8]

[0540] Except that the thickness of the first layer is 1 μm, the laminate is fabricated in the same manner as in Example 7.

[0541] [Example 9]

[0542] Except for forming the first layer using the functional layer resin composition 5 described below, the laminate was prepared in the same manner as in Example 7.

[0543] <Composition of Resin Composition 5 for Functional Layers>

[0544] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0545] • Carbamate acrylate (product name "8UX-047A", manufactured by Taisei Fine Chemicals): 87 parts by weight

[0546] • Pentaerythritol tetraacrylate (product name "ATM-4E", manufactured by Shin-Nakamura Chemical Co., Ltd.): 13 parts by weight

[0547] • High refractive index particles (zirconia, average primary particle size 20 nm, manufactured by CIK Nano Tek): 90 parts by weight (100% conversion of solids).

[0548] Methyl isobutyl ketone: 240 parts by weight

[0549] [Example 10]

[0550] Except that the thickness of the second layer is 60 nm, the laminate is fabricated in the same manner as in Example 9.

[0551] [Example 11]

[0552] Except for using the functional layer resin composition 6 described below to form a first layer with a thickness of 90 nm, the laminate was prepared in the same manner as in Example 7.

[0553] <Composition of Resin Composition 6 for Functional Layers>

[0554] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0555] • Carbamate acrylate (product name "8UX-047A", manufactured by Taisei Fine Chemicals): 87 parts by weight

[0556] • Pentaerythritol tetraacrylate (product name "ATM-4E", manufactured by Shin-Nakamura Chemical Co., Ltd.): 13 parts by weight

[0557] • High refractive index particles (zirconia, average primary particle size 20 nm, manufactured by CIK Nano Tek): 90 parts by weight (100% conversion of solids).

[0558] Methyl isobutyl ketone: 320 parts by weight

[0559] [Example 12]

[0560] Except that the thickness of the first layer is 70 nm, the laminate is fabricated in the same manner as in Example 11.

[0561] [Example 13]

[0562] An example of a substrate layer that also serves as the first layer. As the substrate that also serves as the first layer, a 50 μm thick polyamide-imide film ("CPI" manufactured by Kolon Corporation) is used.

[0563] Next, a second layer with a thickness of 90 nm is formed using the functional layer resin composition 7 described below. Otherwise, the second layer is formed on the first layer in the same manner as in Example 1.

[0564] <Composition of Resin Composition 7 for Functional Layers>

[0565] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0566] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 63 parts by weight

[0567] • Multifunctional acrylate (product name "M-510", manufactured by Dong-A Synthetic Co., Ltd.): 37 parts by weight

[0568] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 90 parts by weight (100% solids conversion).

[0569] Methyl isobutyl ketone: 320 parts by weight

[0570] [Example 14]

[0571] An example where the substrate layer also serves as the first layer. The laminate is prepared in the same manner as in Example 13, except that the second layer is formed using the functional layer resin composition 8 described below.

[0572] <Composition of Resin Composition 8 for Functional Layers>

[0573] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0574] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 70 parts by weight

[0575] • Multifunctional acrylate (product name "M-510", manufactured by Dong-A Synthetic Co., Ltd.): 30 parts by weight

[0576] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 190 parts by weight (100% solids conversion).

[0577] Methyl isobutyl ketone: 340 parts by weight

[0578] [Example 15]

[0579] (1) Formation of the first layer

[0580] The first layer is formed on the substrate layer in the same manner as in Example 1.

[0581] (2) Formation of the second layer

[0582] A second layer is formed on the first layer in the same manner as in Example 13.

[0583] (3) Formation of antifouling layer

[0584] Similar to Example 1, an antifouling layer is formed on the second layer described above.

[0585] [Example 16]

[0586] Except for forming the second layer using the functional layer resin composition 9 described below, the laminate was prepared in the same manner as in Example 15.

[0587] <Composition of Resin Composition 9 for Functional Layers>

[0588] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0589] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 72 parts by weight

[0590] • Multifunctional acrylate (product name "M-510", manufactured by Dong-A Synthetic Co., Ltd.): 28 parts by weight

[0591] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 220 parts by weight (100% solids conversion).

[0592] Methyl isobutyl ketone: 340 parts by weight

[0593] [Example 17]

[0594] (1) Formation of the first layer

[0595] The first layer is formed on the substrate layer in the same manner as in Example 11.

[0596] (2) Formation of the second layer

[0597] A second layer is formed on the first layer in the same manner as in Example 15.

[0598] (3) Formation of antifouling layer

[0599] Similar to Example 1, an antifouling layer is formed on the second layer described above.

[0600] [Example 18]

[0601] An example of a substrate layer that also serves as the first layer. As the substrate that also serves as the first layer, a 50 μm thick polyamide-imide film ("CPI" manufactured by Kolon Corporation) is used.

[0602] Next, the thickness of the second layer is 15 μm, and the second layer is formed on the first layer in the same manner as in Example 1.

[0603] [Comparative Example 1]

[0604] The substrate layer used in Example 13 is used as Comparative Example 1.

[0605] [Comparative Example 2]

[0606] An example where the substrate layer also serves as the first layer. A second layer with a thickness of 3 μm is formed using the functional layer resin composition 10 described below, otherwise the laminate is prepared in the same manner as in Example 18.

[0607] <Composition of Resin Composition 10 for Functional Layers>

[0608] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0609] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 72 parts by weight

[0610] • Multifunctional acrylate (product name "M-510", manufactured by Dong-A Synthetic Co., Ltd.): 28 parts by weight

[0611] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 10 parts by weight (100% solids conversion).

[0612] Methyl isobutyl ketone: 200 parts by weight

[0613] [Comparative Example 3]

[0614] An example where the substrate layer also serves as the first layer. A second layer with a thickness of 3 μm is formed using the following functional layer resin composition 11, otherwise the laminate is prepared in the same manner as in Example 18.

[0615] <Composition of Resin Composition 11 for Functional Layers>

[0616] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0617] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 88 parts by weight

[0618] • Multifunctional acrylate (product name "M-510", manufactured by Dong-A Synthetic Co., Ltd.): 12 parts by weight

[0619] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 280 parts by weight (100% solids conversion).

[0620] Methyl isobutyl ketone: 250 parts by weight

[0621] [Comparative Example 4]

[0622] Except for forming the first layer using the functional layer resin composition 12 described below, the laminate was prepared in the same manner as in Example 1.

[0623] <Composition of Resin Composition 12 for Functional Layers>

[0624] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0625] • Carbamate acrylate (product name "8UX-047A", manufactured by Taisei Fine Chemicals): 20 parts by weight

[0626] • Pentaerythritol tetraacrylate (product name "ATM-4E", manufactured by Shin-Nakamura Chemical Co., Ltd.): 80 parts by weight

[0627] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 30 parts by weight (100% solids conversion).

[0628] Methyl isobutyl ketone: 200 parts by weight

[0629] [Comparative Example 5]

[0630] (1) Formation of the first layer

[0631] Except for using the functional layer resin composition 13 described below, a first layer is formed on the substrate layer in the same manner as in Example 1.

[0632] <Composition of Resin Composition 13 for Functional Layers>

[0633] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0634] • Carbamate acrylate (product name "8UX-047A", manufactured by Taisei Fine Chemicals): 92 parts by weight

[0635] • Pentaerythritol tetraacrylate (product name "ATM-4E", manufactured by Shin-Nakamura Chemical Co., Ltd.): 8 parts by weight

[0636] • High refractive index particles (zirconia, average primary particle size 20 nm, manufactured by CIK Nano Tek): 230 parts by weight (100% solids conversion).

[0637] Methyl isobutyl ketone: 280 parts by weight

[0638] (2) Formation of the second layer

[0639] A second layer is formed on the first layer as in Example 14.

[0640] (3) Formation of antifouling layer

[0641] Similar to Example 1, an antifouling layer is formed on the second layer described above.

[0642] [Comparative Example 6]

[0643] (1) Formation of the first layer

[0644] The first layer is formed on the substrate layer in the same manner as in Example 9.

[0645] (2) Formation of the second layer

[0646] Except that the thickness is 40 nm, a second layer is formed on the first layer as described in Example 13.

[0647] (3) Formation of antifouling layer

[0648] Similar to Example 1, an antifouling layer is formed on the second layer described above.

[0649] [Comparative Example 7]

[0650] (1) Formation of the first layer

[0651] Except for using the functional layer resin composition 14 described below, a first layer is formed on the substrate layer in the same manner as in Example 1.

[0652] <Composition of Resin Composition 14 for Functional Layers>

[0653] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0654] • Carbamate acrylate (product name "8UX-047A", manufactured by Taisei Fine Chemicals): 92 parts by weight

[0655] • Pentaerythritol tetraacrylate (product name "ATM-4E", manufactured by Shin-Nakamura Chemical Co., Ltd.): 8 parts by weight

[0656] • High refractive index particles (zirconia, average primary particle size 20 nm, manufactured by CIK Nano Tek): 200 parts by weight (100% conversion of solids content).

[0657] Methyl isobutyl ketone: 270 parts by weight

[0658] (2) Formation of the second layer

[0659] A second layer is formed on the first layer in the same manner as in Example 16.

[0660] (3) Formation of antifouling layer

[0661] Similar to Example 1, an antifouling layer is formed on the second layer described above.

[0662] [Comparative Example 8]

[0663] (1) Formation of the first layer

[0664] Except for using the functional layer resin composition 15 described below, a first layer is formed on the substrate layer in the same manner as in Example 1.

[0665] <Composition of Resin Composition 15 for Functional Layers>

[0666] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0667] • Carbamate acrylate (product name "8UX-047A", manufactured by Taisei Fine Chemicals): 46 parts by weight

[0668] • Pentaerythritol tetraacrylate (product name "ATM-4E", manufactured by Shin-Nakamura Chemical Co., Ltd.): 54 parts by weight

[0669] Methyl isobutyl ketone: 200 parts by weight

[0670] (2) Formation of the second layer

[0671] A second layer is formed on the first layer in the same manner as in Example 13.

[0672] (3) Formation of antifouling layer

[0673] Similar to Example 1, an antifouling layer is formed on the second layer described above.

[0674] [evaluate]

[0675] (1) Visual reflectance

[0676] The visual reflectance was determined according to JIS Z8722:2009. Based on the reflectance spectrum obtained by incident light in the wavelength range of 380nm to 780nm onto the surface of the second layer of the laminate, the tristimulus values ​​X, Y, and Z in the XYZ chromaticity system were determined within a 2-degree field of view of standard light C. This Y value was taken as the visual reflectance. In the measurement of visual reflectance, a Shimadzu UV-2600 spectrophotometer was used under the following conditions. It should be noted that, to prevent back reflection, a black vinyl tape (product name "YamatoVinyl Tape NO200-19-21", manufactured by YAMATO, 19mm wide) with a width greater than the area of ​​the measurement point was attached to the back of the laminate before measurement.

[0677] (Measurement conditions)

[0678] • Field of view: 2°

[0679] • Illuminating element: C

[0680] • Light source: Tungsten halogen lamp

[0681] • Measurement wavelength: 380nm to 780nm, with intervals of 0.5nm.

[0682] • Scanning speed: High speed

[0683] • Slit width: 5.0nm

[0684] • S / R switching: Standard

[0685] • Automatic zeroing: Performed at 550nm after baseline scan

[0686] (2) Yellowness

[0687] Yellowness (YI) was determined according to JIS K7373:2006. Specifically, using a UV-Vis-NIR spectrophotometer (V-7100 manufactured by Nippon Spectrophotometer Co., Ltd.), measurements were taken at 0.5 nm intervals in the range of 300 nm to 780 nm using a deuterium lamp and a tungsten halogen lamp via spectrophotometry. Based on the obtained transmittance, the tristimulus values ​​X, Y, and Z in the XYZ colorimetric system were determined in a 2-degree field of view of standard light C. These X, Y, and Z values ​​were then used to calculate the yellowness using the following formula. Furthermore, the following conditions were observed during the measurement of yellowness.

[0688] YI = 100(1.2769X - 1.0592Z) / Y

[0689] (Measurement conditions)

[0690] • Field of view: 2°

[0691] • Illuminating element: C

[0692] • Light source: deuterium lamps and tungsten halogen lamps

[0693] • Measurement wavelength: 300nm to 780nm, with intervals of 0.5nm.

[0694] • Scanning speed: High speed

[0695] • Slit width: 5.0nm

[0696] • S / R switching: Standard

[0697] • Automatic zeroing: Performed at 550nm after baseline scan

[0698] (3) Dynamic bending

[0699] The following dynamic bending test was performed on the laminate to evaluate its bending resistance. First, a laminate measuring 50mm × 200mm was prepared. Using a durability testing machine (product name "DLDMLH-FS", manufactured by Yuasa System Equipment Co., Ltd.), as shown in Figure 4(a), the short side 1C of the laminate 1 for display devices and the short side 1D opposite to the short side 1C were fixed using parallel fixing parts 51. Next, as shown in Figure 4(b), the fixing parts 51 were moved closer together, thereby deforming the laminate 1 for display devices in a folding manner. Then, as shown in Figure 4(c), the fixing parts 51 were moved until the distance d between the two opposing short sides 1C and 1D fixed by the fixing parts 51 of the laminate 1 for display devices reached a specified value. After that, the fixing parts 51 were moved in the opposite direction to eliminate the deformation of the laminate 1 for display devices. As shown in Figures 4(a) to (c), the display device laminate 1 is repeatedly folded 180° by moving the fixing part 51. During this process, the distance d between the two opposing short sides 1C and 1D of the display device laminate 1 is 10 mm. Furthermore, the case where the laminate is bent with the second layer as the inner side is defined as an inner bend, and the case where it is bent with the second layer as the outer side is defined as an outer bend. The results of the dynamic bending test are evaluated according to the following criteria.

[0700] A: Even after bending 300,000 times, the laminate did not crack or break.

[0701] B: Before bending 300,000 times, cracks or fractures occurred in the laminate.

[0702] (4) Visibility

[0703] After conducting the dynamic bending test on the laminate, the laminate was attached to the surface of the foldable display (Lenovo's "ThinkPad X1 Fold") with the bending position and direction of the laminate aligned with those of the foldable display, and with the second layer side of the laminate as the surface. Visibility was then verified. At this time, the angle θ2 of the foldable display 20, as shown in Figure 3, was set to 120°. Furthermore, the normal to the surface of the first display area 22 of the foldable display 20 was set to 60°, and the normal to the surface of the second display area 23 was set to 15°.

[0704] Regarding the visibility of the first display area 22 of the foldable display screen 20 shown in Figure 3, text is displayed and it is confirmed whether the text can be visually recognized.

[0705] In addition, regarding the visibility of the first display area 22 and the second display area 23 of the foldable display screen 20 shown in Figure 3, an image is displayed and the first display area 22 is observed. Then, the line of sight is moved only to observe the second display area 23 to confirm whether there is any sense of incongruity at this time.

[0706] In addition, regarding the visibility of the curved portion 21 of the foldable display screen 20 shown in Figure 3, an image is displayed to confirm whether there is any visual incongruity between the curved portion 21 and other areas.

[0707] The visibility of the first display area, the visibility of the first and second display areas, and the visibility of the curved portion are confirmed separately, and a comprehensive evaluation is performed according to the following criteria.

[0708] A: All 10 out of 10 people visually identified the first display area, the second display area, and the curved section without any problems.

[0709] B: 7 to 9 out of 10 people visually identified that there were no problems with the first display area, the second display area, and the curved part.

[0710] C: Four to six out of ten people visually identified the first display area, the second display area, and the curved section without any problems.

[0711] D: Of the 10 people, fewer than 4 people were able to visually identify the first display area, the second display area, and the curved section without any problems.

[0712]

[0713] In the laminates of Examples 1 to 18, the apparent reflectance of the orthophoto at an incident angle of 60° is below a predetermined value, and the absolute value of the difference between the yellowness YI1 of the transmitted light in the 60° direction and the yellowness YI2 of the transmitted light in the 15° direction is below a predetermined value. Therefore, the visibility of the first display area and the visibility of the first and second display areas are good, and the visibility is good in the usage mode of viewing the image with the foldable display screen bent. On the other hand, in the laminates of Comparative Examples 1 to 8, the apparent reflectance of the orthophoto at an incident angle of 60°, or the absolute value of the difference between the yellowness YI1 of the transmitted light in the 60° direction and the yellowness YI2 of the transmitted light in the 15° direction, are not within the predetermined range. Therefore, the visibility of the first display area or the visibility difference between the first and second display areas is poor, and the visibility is poor in the usage mode of viewing the image with the foldable display screen bent.

[0714] Furthermore, in the laminates of Examples 1 to 17, the thickness of the second layer is within a specified range, thus exhibiting good dynamic bending properties and good visibility of the bent portion.

[0715] II. Examples of the second embodiment

[0716] Next, Examples 1 to 10 of the second embodiment and Comparative Examples 1 to 8 will be described.

[0717] [Example 1]

[0718] (1) Formation of hard coating

[0719] First, the components are mixed in the manner shown below to obtain resin composition 1 for functional layer.

[0720] <Composition of Resin Composition 1 for Functional Layers>

[0721] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0722] • Carbamate acrylate (product name "UV-7000B", manufactured by Mitsubishi Chemical Corporation): 100 parts by weight

[0723] • Silica particles (average primary particle size 12nm, manufactured by Nissan Chemical Industries, Ltd.): 35 parts by weight (100% solids conversion).

[0724] Methyl isobutyl ketone: 220 parts by weight

[0725] Next, as the substrate layer, a 50 μm thick polyimide film (Neoprim manufactured by Mitsubishi Gas Chemical Co., Ltd.) was coated onto the substrate layer using a doctor blade coater to form the aforementioned functional layer resin composition 1. Afterwards, the coating film was heated to 70°C for 1 minute to evaporate the solvent, and then irradiated with ultraviolet light (FusionUV Systems Japan, H-bulb light source) at an oxygen concentration of 200 ppm and a cumulative light intensity of 40 mJ / cm². 2 The coating is cured by irradiating it with ultraviolet light, forming a hard coating with a thickness of 3μm.

[0726] (2) Formation of the second functional layer

[0727] The components are mixed in the manner shown below to obtain resin composition 2 for functional layers.

[0728] <Composition of Resin Composition 2 for Functional Layers>

[0729] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0730] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 70 parts by weight

[0731] • Pentaerythritol acrylate (product name "A-TMM-3", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): 30 parts by weight

[0732] • High refractive index particles (zirconia, average primary particle size 11 nm, manufactured by Nippon Shokubai Co., Ltd.): 100 parts by weight (100% solids conversion).

[0733] Methyl isobutyl ketone: 230 parts by weight

[0734] Next, the functional layer resin composition 2 is applied to the hard coating layer using a doctor blade coater to form a coating film. Then, the coating film is heated to 70°C for 1 minute to evaporate the solvent, and then irradiated with ultraviolet light (using an H-bulb light source manufactured by Fusion UV Systems Japan) at an oxygen concentration of less than 200 ppm and a cumulative light intensity of 400 mJ / cm². 2 The coating is cured by irradiating it with ultraviolet light to form a second functional layer with a thickness of 3μm.

[0735] (3) Formation of functional layers

[0736] The surface of the second functional layer was modified by plasma treatment at an output of 200W for 180 seconds. Subsequently, a low-refractive-index inorganic material (silica) was deposited on the surface-modified second functional layer using a vacuum evaporation apparatus (manufactured by ULVAC) to form a functional layer with a thickness of 90 nm.

[0737] (4) Formation of antifouling layer

[0738] The surface of the aforementioned functional layer was modified by plasma treatment at an output of 200W for 60 seconds. Subsequently, a fluorine compound (product name "OPTOOL UD120", manufactured by Daikin Industries) was deposited on the surface-modified functional layer using a vacuum evaporation apparatus (manufactured by ULVAC) to form an antifouling layer with a thickness of 7nm.

[0739] [Example 2]

[0740] Except for forming the second functional layer using the following functional layer resin composition 3, the laminate was prepared in the same manner as in Example 1.

[0741] <Composition of Resin Composition 3 for Functional Layers>

[0742] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0743] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 83 parts by weight

[0744] • Pentaerythritol acrylate (product name "A-TMM-3", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): 17 parts by weight

[0745] • High refractive index particles (zirconia, average primary particle size 11 nm, manufactured by Nippon Shokubai Co., Ltd.): 180 parts by weight (converted from 100% solids content).

[0746] Methyl isobutyl ketone: 250 parts by weight

[0747] [Example 3]

[0748] Except for forming the second functional layer using the following functional layer resin composition 4, the laminate was prepared in the same manner as in Example 1.

[0749] <Composition of Resin Composition 4 for Functional Layers>

[0750] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0751] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 70 parts by weight

[0752] • Pentaerythritol acrylate (product name "A-TMM-3", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): 30 parts by weight

[0753] • High refractive index particles (zirconia, average primary particle size 11 nm, manufactured by Nippon Shokubai Co., Ltd.): 70 parts by weight (100% solids conversion).

[0754] Methyl isobutyl ketone: 230 parts by weight

[0755] [Example 4]

[0756] Except for forming a second functional layer with a thickness of 70 nm using the following functional layer resin composition 5, the laminate was prepared in the same manner as in Example 1.

[0757] <Composition of Resin Composition 5 for Functional Layers>

[0758] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0759] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 70 parts by weight

[0760] • Pentaerythritol acrylate (product name "A-TMM-3", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): 30 parts by weight

[0761] • High refractive index particles (zirconia, average primary particle size 11 nm, manufactured by Nippon Shokubai Co., Ltd.): 100 parts by weight (100% solids conversion).

[0762] Methyl isobutyl ketone: 320 parts by weight

[0763] [Example 5]

[0764] Except that the thickness of the second functional layer is 1 μm, the laminate is fabricated in the same manner as in Example 1.

[0765] [Example 6]

[0766] The laminate was fabricated in the same manner as in Example 1, except that the thickness of the second functional layer was 10 μm.

[0767] [Example 7]

[0768] Except that the thickness of the functional layer is 120 nm, the laminate is fabricated in the same manner as in Example 1.

[0769] [Example 8]

[0770] Except that the thickness of the functional layer is 60 nm, the laminate is fabricated in the same manner as in Example 1.

[0771] [Example 9]

[0772] Except for the formation of functional layers having high and low refractive index films as described below, the laminate is fabricated in the same manner as in Example 1.

[0773] First, the surface of the second functional layer was modified by plasma treatment at an output of 200W for 180 seconds. Then, a high-refractive-index inorganic material (zirconia) was deposited on the surface-modified second functional layer using a vacuum evaporation apparatus (manufactured by ULVAC) to form a high-refractive-index film with a thickness of 10 nm.

[0774] Next, the surface of the high-refractive-index film was modified by plasma treatment at an output of 200W for 120 seconds. Subsequently, a low-refractive-index film with a thickness of 110 nm was formed on the surface-modified high-refractive-index film by vacuum evaporation using a vacuum evaporation apparatus (manufactured by ULVAC).

[0775] [Example 10]

[0776] Except that the thickness of the second functional layer is 140 nm, the laminate is fabricated in the same manner as in Example 4.

[0777] [Comparative Example 1]

[0778] Except for forming the second functional layer using the following functional layer resin composition 6, the laminate was prepared in the same manner as in Example 1.

[0779] <Composition of Resin Composition 6 for Functional Layers>

[0780] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0781] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 40 parts by weight

[0782] • Pentaerythritol acrylate (product name "A-TMM-3", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): 60 parts by weight

[0783] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 35 parts by weight (100% solids conversion).

[0784] Methyl isobutyl ketone: 220 parts by weight

[0785] [Comparative Example 2]

[0786] In the formation of the second functional layer, the surface treatment conditions are changed to output 100W, and the laminate is otherwise fabricated in the same manner as in Example 1.

[0787] [Comparative Example 3]

[0788] In the formation of the second functional layer, the surface treatment conditions are changed to output 400W, and the laminate is otherwise fabricated in the same manner as in Example 1.

[0789] [Comparative Example 4]

[0790] The following steps are performed to form a functional layer with a high refractive index film and a low refractive index film, otherwise the laminate is fabricated in the same manner as in Example 1.

[0791] First, the surface of the second functional layer was modified by plasma treatment at an output of 200W for 180 seconds. Then, a high-refractive-index inorganic material (zirconia) was deposited on the surface-modified second functional layer using a vacuum evaporation apparatus (manufactured by ULVAC) to form a high-refractive-index film with a thickness of 80 nm.

[0792] Next, the surface of the high-refractive-index film was modified by plasma treatment at an output of 200W for 120 seconds. Subsequently, a low-refractive-index film with a thickness of 90 nm was formed on the surface-modified high-refractive-index film by vacuum evaporation using a vacuum evaporation apparatus (manufactured by ULVAC).

[0793] [Comparative Example 5]

[0794] Except that the thickness of the functional layer is 150 nm, the laminate is fabricated in the same manner as in Example 1.

[0795] [Comparative Example 6]

[0796] Except that the thickness of the functional layer is 40 nm, the laminate is fabricated in the same manner as in Example 1.

[0797] [Comparative Example 7]

[0798] Except for the formation of the second functional layer and the functional layer as described below, the laminate is fabricated in the same manner as in Example 1.

[0799] (1) Formation of the second functional layer

[0800] Except for using the following functional layer resin composition 7, a second functional layer is formed in the same manner as in Example 1.

[0801] <Composition of Resin Composition 7 for Functional Layers>

[0802] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0803] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 70 parts by weight

[0804] • Pentaerythritol acrylate (product name "A-TMM-3", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): 30 parts by weight

[0805] • High refractive index particles (titanium oxide, average primary particle size 5 nm, manufactured by Resino Color Industry): 270 parts by weight (100% solids conversion).

[0806] Methyl isobutyl ketone: 250 parts by weight

[0807] (2) Formation of functional layers

[0808] The surface of the second functional layer was modified by plasma treatment at 400W for 180 seconds. Subsequently, a low-refractive-index inorganic material (silica) was deposited on the surface-modified second functional layer using a vacuum evaporation apparatus (manufactured by ULVAC) to form a functional layer with a thickness of 90nm.

[0809] [Comparative Example 8]

[0810] The second functional layer is formed as follows, and a functional layer having a high refractive index film and a low refractive index film is formed. Otherwise, the laminate is fabricated in the same manner as in Example 1.

[0811] (1) Formation of the second functional layer

[0812] Except for using the following functional layer resin composition 8, a second functional layer is formed in the same manner as in Example 1.

[0813] <Composition of Resin Composition 8 for Functional Layers>

[0814] • Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 3 parts by weight

[0815] • Carbamate acrylate (product name "EBECRYL 8209", manufactured by Daicel Allnex): 100 parts by weight

[0816] • Low refractive index particles (hollow silica, average primary particle size 50nm, manufactured by Nichibukai Catalyst Chemical Co., Ltd.): 40 parts by weight (100% solids conversion).

[0817] Methyl isobutyl ketone: 220 parts by weight

[0818] (2) Formation of functional layers

[0819] The surface of the second functional layer was modified by plasma treatment at an output of 200W for 180 seconds. Subsequently, a high-refractive-index inorganic material (zirconia) was deposited on the surface-modified second functional layer using a vacuum evaporation apparatus (manufactured by ULVAC) to form a first high-refractive-index film with a thickness of 30 nm.

[0820] Next, the surface of the first high-refractive-index film was modified by plasma treatment at an output of 200W for 150 seconds. Subsequently, a first low-refractive-index film with a thickness of 20 nm was formed on the surface-modified first high-refractive-index film by vacuum evaporation using a vacuum evaporation apparatus (manufactured by ULVAC).

[0821] Next, the surface of the first low-refractive-index film was modified by plasma treatment at an output of 200W for 120 seconds. Subsequently, a second high-refractive-index film with a thickness of 30 nm was formed on the surface-modified first low-refractive-index film by vacuum evaporation using a vacuum evaporation apparatus (manufactured by ULVAC).

[0822] Next, the surface of the second high-refractive-index film was modified by plasma treatment at an output of 200W for 90 seconds. Subsequently, a low-refractive-index inorganic material (silica) was deposited on the surface-modified second high-refractive-index film using a vacuum evaporation apparatus (manufactured by ULVAC) via vacuum evaporation, forming a second low-refractive-index film with a thickness of 90 nm.

[0823] [evaluate]

[0824] (1) Visual reflectance

[0825] The visual reflectance was determined according to JIS Z8722:2009. Based on the reflectance spectrum obtained by incident light in the wavelength range of 380nm to 780nm onto the functional layer side of the laminate, the tristimulus values ​​X, Y, and Z in the XYZ chromaticity system were determined within a 2-degree field of view of standard light C. This Y value was taken as the visual reflectance. In the measurement of visual reflectance, a Shimadzu UV-2600 spectrophotometer was used under the following conditions. It should be noted that, to prevent back reflection, a black vinyl tape (product name "YamatoVinyl Tape NO200-19-21", manufactured by YAMATO, 19mm wide) with a width larger than the area of ​​the measurement point was attached to the back of the laminate before measurement.

[0826] (Measurement conditions)

[0827] • Field of view: 2°

[0828] • Illuminating element: C

[0829] • Light source: Tungsten halogen lamp

[0830] • Measurement wavelength: 380nm to 780nm, with intervals of 0.5nm.

[0831] • Scanning speed: High speed

[0832] • Slit width: 5.0nm

[0833] • S / R switching: Standard

[0834] • Automatic zeroing: Performed at 550nm after baseline scan

[0835] (2) The maximum load at which the functional layer does not peel off during the steel wool test after surface modification.

[0836] First, using the corona discharge surface modification device "Corona Scanner ASA-4" manufactured by Shin-Kuang Electric Equipment Co., Ltd., the laminate is installed on the worktable of the corona scanner with the antifouling layer side facing up. The entire surface of the antifouling layer side of the laminate is subjected to corona discharge treatment under the following conditions.

[0837] Output voltage: 14kV

[0838] • Distance from the antifouling layer side of the laminated body for display devices to the electrodes of the corona discharge treatment device: 2mm

[0839] • Stage movement speed of the corona scanner: 30 mm / second

[0840] Next, using a vibration-type friction fastness tester AB-301 manufactured by TESTERSANGYO, a 5cm × 10cm laminate was fixed to a glass plate with celluloid tape to ensure a smooth, wrinkle-free surface. Then, using #0000 steel wool (Bonstar #0000 manufactured by Japan Steel Wool Co., Ltd.), the steel wool was fixed to a 1cm × 1cm clamp and subjected to a load of 100g / cm². 2 Under the conditions of a moving speed of 100 mm / s and a moving distance of 50 mm, the anti-fouling layer side of the display device is rubbed back and forth 100 times. Afterwards, the load is increased from 100 g / cm². 2 Starting from per 100g / cm 2 Gradually increase the load to find the maximum load that will not cause functional layer stripping.

[0841] (3) Dynamic bending

[0842] The following dynamic bending test was performed on the laminate to evaluate its bending resistance. First, a laminate of size 50mm × 200mm was prepared. For a durability testing machine (product name "DLDMLH-FS", manufactured by Yuasa System Equipment Co., Ltd.), as shown in Figure 4(a), the short side 1C of the laminate 1 (41) for display devices and the short side 1D opposite to the short side 1C were fixed by parallel fixing parts 51. Next, as shown in Figure 4(b), the fixing parts 51 were moved closer to each other, thereby deforming the laminate 1 (41) for display devices in a folding manner. Then, as shown in Figure 4(c), the fixing parts 51 were moved to a position where the interval d between the two opposing short sides 1C and 1D fixed by the fixing parts 51 of the laminate 1 (41) for display devices reached a specified value. After that, the fixing parts 51 were moved in the opposite direction to eliminate the deformation of the laminate 1 (41) for display devices. As shown in Figures 4(a) to (c), the display device laminate 1 was repeatedly folded 180° by moving the fixing part 51. At this time, the interval d between the two opposing short sides 1C and 1D of the display device laminate 1 (41) was 10 mm. In addition, the case where the laminate was bent with the functional layer on the inside was called the inner bend, and the case where it was bent with the functional layer on the outside was called the outer bend. The results of the dynamic bending test were evaluated according to the following criteria.

[0843] A: Even after bending 300,000 times, the laminate did not crack or break.

[0844] B: Before bending 300,000 times, cracks or fractures occurred in the laminate.

[0845] (4) Visibility

[0846] After conducting the dynamic bending test on the laminate, the laminate was attached to the surface of the foldable display (Lenovo's "ThinkPad X1 Fold") with the bending position and direction of the laminate aligned with those of the foldable display, and with the functional layer side of the laminate as the surface. Visibility was then verified. At this time, for example, as shown in Figure 12, the angle θ2 of the foldable display 20 was set to 120°.

[0847] Regarding the visibility of the first display area 22 of the foldable display screen 20 shown in Figure 12, text is displayed and it is confirmed whether the text can be visually recognized.

[0848] In addition, regarding the visibility of the curved portion 21 of the foldable display screen 20 shown in Figure 12, an image is displayed to confirm whether there is any visual incongruity between the curved portion 21 and other areas.

[0849] Visibility was evaluated according to the following criteria.

[0850] A: All 10 out of 10 people were able to visually identify the individuals without any problems.

[0851] B: Visual identification was conducted on 7 to 9 out of 10 people without any problems.

[0852] C: Visual identification was conducted without any problems for 4 to 6 out of 10 people.

[0853] D: Of the 10 people, fewer than 4 were able to visually identify the individuals without any problems.

[0854]

[0855] In the laminates of Examples 1 to 10, the apparent reflectivity of the orthogonal reflected light at an incident angle of 60° is below a specified value, and the maximum load at which the functional layer does not peel off during the steel wool test after the above surface modification is within a specified range. Therefore, the visibility of the first display area is good, the visibility is good in the usage mode of observing the image in the state of bending the foldable display screen, and the dynamic bending performance is excellent, with good visibility of the bent portion.

[0856] On the other hand, in the laminate of Comparative Example 1, the apparent reflectivity of the orthogonal reflected light at an incident angle of 60° is high, resulting in poor visibility of the first display area. This is because the difference in refractive index between the functional layer and the second functional layer is small, leading to a low reflection suppression effect.

[0857] In the functional layer of Comparative Example 2, due to the small output of the surface treatment (plasma treatment) of the second functional layer, the adhesion between the second functional layer and the functional layer is insufficient. As a result, the maximum load at which the functional layer does not peel off during the steel wool test after the above surface modification is small, the dynamic bending performance is poor, and the visibility of the bending part is poor.

[0858] In the laminate of Comparative Example 3, due to the large output of the surface treatment (plasma treatment) of the second functional layer, the adhesion between the second functional layer and the functional layer is excessive. As a result, the maximum load at which the functional layer does not peel off during the steel wool test after the above surface modification is large, the dynamic bending performance is poor, and the visibility of the bending part is poor.

[0859] In the laminate of Comparative Example 4, the maximum load at which the functional layer does not peel off during the steel wool test after the above surface modification is large, the dynamic bending performance is poor, and the visibility of the bending part is poor.

[0860] The reason is that although there are two functional layers, the overall thickness of the functional layer is too thick, resulting in excessive tightness and poor flexibility.

[0861] In the laminate of Comparative Example 5, the maximum load at which the functional layer does not peel off during the steel wool test after the above surface modification is large, the dynamic bending performance is poor, and the visibility of the bending part is poor.

[0862] The reason is that, due to the thickness of the functional layer, the functional layer has excessive tightness and poor flexibility.

[0863] In the laminate of Comparative Example 6, the apparent reflectivity of the orthogonal reflected light at an incident angle of 60° is high, resulting in poor visibility in the first display area. This is because the functional layer is thin, leading to a low reflection suppression effect. Furthermore, in the laminate of Comparative Example 6, the maximum load at which the functional layer does not peel off during the steel wool test after the aforementioned surface modification is small, resulting in poor dynamic bending performance and poor visibility at the bent portion. This is because the functional layer is thin, resulting in low hardness and insufficient adhesion.

[0864] In the laminate of Comparative Example 7, although the output of the surface treatment (plasma treatment) of the second functional layer is large, the adhesion of the functional layer is insufficient due to the high content of inorganic particles in the second functional layer. As a result, the maximum load at which the functional layer does not peel off during the steel wool test after the above surface modification is small, the dynamic bending performance is poor, and the visibility of the bending part is poor.

[0865] In the laminate of Comparative Example 8, the maximum load at which the functional layer does not peel off during the steel wool test after the above surface modification is large, the dynamic bending performance is poor, and the visibility of the bending part is poor.

[0866] The reason is that, due to the large number of functional layers and the overall thickness of the functional layers, the functional layers have excessive tightness and poor flexibility.

[0867] Explanation of symbols

[0868] 1, 41…Laminated materials for display devices

[0869] 2, 42… Substrate layer

[0870] 3… Level 1

[0871] 4…2nd floor

[0872] 5, 45… hard coating

[0873] 6, 46… Impact Absorption Layer

[0874] 7, 47… Adhesive layer for application

[0875] 8, 48… Anti-fouling layer

[0876] 30… Display device

[0877] 31… Display Panel

[0878] 43… Functional Layer

[0879] 44…Second functional layer

Claims

1. A laminate for a display device, comprising a substrate layer, a first layer, and a second layer sequentially, wherein, When light is incident at an angle of incidence of 60° onto the surface of the second layer of the laminate for the display device, the apparent reflectivity of the positively reflected light is 10.0% or less, the absolute value of the difference between the yellowness YI1 of the transmitted light in a direction with a normal of 60° to the surface of the second layer of the laminate for the display device and the yellowness YI2 of the transmitted light in a direction with a normal of 15° to the surface of the second layer of the laminate for the display device is 3.0 or less, the thickness of the second layer is 1 μm or more and 10 μm or less, and the refractive index of the second layer is 1.40 or more and 1.50 or less.

2. A laminate for a display device, comprising a substrate layer, a first layer, and a second layer sequentially, wherein, When light is incident at an angle of 60° onto the surface of the second layer of the laminate for the display device, the apparent reflectivity of the positively reflected light is 10.0% or less, the absolute value of the difference between the yellowness YI1 of the transmitted light in a direction with a normal of 60° to the surface of the second layer of the laminate for the display device and the yellowness YI2 of the transmitted light in a direction with a normal of 15° to the surface of the second layer of the laminate for the display device is 3.0 or less, the thickness of the second layer is 50 nm or more and 1 μm or less, and the ratio of the refractive index of the first layer to the refractive index of the second layer is 1.05 or more and 1.20 or less.

3. The laminate for a display device as described in claim 1 or claim 2, wherein, The substrate layer also serves as the first layer.

4. The laminate for a display device as described in claim 1 or claim 2, wherein, A hard coating is provided between the substrate layer and the first layer.

5. The laminate for a display device as described in claim 1 or claim 2, wherein, An impact-absorbing layer is provided on the side of the substrate layer opposite to the first layer, or between the substrate layer and the first layer.

6. The laminate for a display device as claimed in claim 1 or claim 2, wherein, An adhesive layer for attachment is provided on the side of the substrate layer opposite to the first layer.

7. The laminate for a display device as claimed in claim 1 or claim 2, wherein, The second layer has a stain-resistant layer on the side opposite to the first layer.

8. The laminate for a display device as claimed in claim 1 or claim 2, wherein, A sample of the display device laminate measuring 50mm × 200mm was prepared. The sample underwent 200,000 cycles of dynamic bending tests with 180° folding at 30mm intervals between the opposing short sides of the sample. No cracking or breakage occurred.

9. A display device comprising: a display panel; and a laminate for a display device as described in any one of claims 1 to 8 disposed on the observer side of the display panel.

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