Optical sheet, sheet article, polarizing plate, display device, panel, method for selecting optical sheet, and method for manufacturing optical sheet

Abstract

The optical sheet includes a first side and a second side opposite to the first side. The optical sheet comprises a substrate and a functional layer in order from the second side towards the first side. The functional layer comprises an adhesive component and metal oxide particles. The average area of ​​the Voronoi region, with the metal oxide particles observed on the first side as the parent point, is 2500 nm. 2 above.

Description

Technical Field

[0001] This disclosure relates to optical sheets, sheet articles, polarizers, display devices, panels, methods for selecting optical sheets, and methods for manufacturing optical sheets. Background Technology

[0002] As disclosed in Patent Document 1, optical sheets containing a functional layer are known. The functional layer contains metal oxide particles. The functional layer is expected to provide optical functions due to the metal oxide particles. In Patent Document 1, the functional layer functions as a low-reflection layer containing hollow silicon dioxide.

[0003] During the use of optical sheets, metal oxide particles can detach from the functional layer. These particles can also deform during use. Due to the detachment or deformation of the metal oxide particles, optical sheets containing the functional layer have low scratch resistance.

[0004] Patent Document 1: WO2021 / 020504 Summary of the Invention

[0005] The purpose of this disclosure is to improve the scratch resistance of optical sheets containing functional layers.

[0006] One embodiment of the optical sheet disclosed herein includes a first surface and a second surface opposite to the first surface, wherein a substrate and a functional layer are sequentially provided from the second surface toward the first surface. The functional layer comprises an adhesive component and metal oxide particles, with the average area of ​​the Voronoi region, with the metal oxide particles as parent points as observed on the first surface, being 2500 nm. 2 above.

[0007] An article of one embodiment of the present disclosure comprises any one of a plurality of optical sheets of one embodiment of the present disclosure.

[0008] A polarizer according to one embodiment of the present disclosure includes a first protective sheet, a polarizer and a second protective sheet, wherein at least one of the first protective sheet and the second protective sheet is any of the optical sheets according to one embodiment of the present disclosure.

[0009] A display device according to one embodiment of the present disclosure includes: an image forming apparatus; and any one of the optical sheets of one embodiment of the present disclosure that overlaps with the image forming apparatus.

[0010] A panel according to one embodiment of the present disclosure includes: an article to be joined; and any one of the optical sheets of an embodiment of the present disclosure to be joined with the article to be joined.

[0011] One embodiment of the optical sheet selection method disclosed herein includes: For an optical sheet, the step of measuring the average area of ​​a Voronoi region with metal oxide particles observed on a first surface as mother points, the optical sheet having a first surface and a second surface opposite the first surface, and having a substrate and a functional layer sequentially disposed from the second surface toward the first surface, the functional layer comprising an adhesive component and metal oxide particles; and The average area (nm) of the selected Voronoi region was selected. 2 The step of using an optical sheet with a specified value or higher.

[0012] One embodiment of the present disclosure includes a method for manufacturing an optical sheet comprising: The steps of manufacturing an optical sheet include: the optical sheet having a first surface and a second surface opposite to the first surface; a substrate and a functional layer being sequentially formed from the second surface toward the first surface; the functional layer comprising an adhesive component and metal oxide particles; and... The average area (nm) of the Voronoi region, selected with the metal oxide particles observed on the first surface as the parent point, was chosen. 2 The step of using an optical sheet with a specified value or higher.

[0013] According to the present invention, the scratch resistance of optical sheets containing functional layers can be improved. Attached Figure Description

[0014] Figure 1 This is a diagram used to illustrate one embodiment, and is a cross-sectional view showing an example of an optical sheet.

[0015] Figure 2 It is a top view used to illustrate the Voronoi region and the mother point.

[0016] Figure 3 Is with Figure 1 The corresponding figure is a cross-sectional view showing other examples of optical sheets.

[0017] Figure 4 This is a perspective view showing an example of a sheet article containing optical plates.

[0018] Figure 5 This is a cross-sectional view showing an example of a polarizer containing optical plates.

[0019] Figure 6 This is a cross-sectional view showing an example of a display device including an optical sheet.

[0020] Figure 7 This is a cross-sectional view showing an example of a panel containing optical sheets.

[0021] Figure 8A This is an observation image showing the first side of the optical sheet of Embodiment 1.

[0022] Figure 8BThis is an image obtained by binarizing the image of the first side of the optical sheet shown in Embodiment 1.

[0023] Figure 8C This is an image showing the distribution of the center positions of the metal oxide particles observed on the first surface of the optical sheet of Example 1.

[0024] Figure 9A This is an image of a Voronoi diagram obtained from an observation image of the first side of the optical sheet of Example 1.

[0025] Figure 9B This is an image showing a Voronoi diagram obtained from an observation image of the first side of the optical sheet of Example 2.

[0026] Figure 9C This is an image showing a Voronoi diagram obtained from an observation image of the first side of the optical sheet of Example 3.

[0027] Figure 9D This is an image of the Voronoi diagram obtained from an observation image of the first side of the optical sheet of Example 4.

[0028] Figure 9E This is an image of the Voronoi diagram obtained from an observation image of the first side of the optical sheet of Example 5.

[0029] Figure 9F This is an image of the Voronoi diagram obtained from the observation image of the first side of the optical sheet of Comparative Example 1.

[0030] Figure 9G This is an image of the Voronoi diagram obtained from the observation image of the first side of the optical sheet of Comparative Example 2. Detailed Implementation

[0031] One embodiment of this disclosure relates to the following <1> ~ <20> .

[0032] <1>

[0033] An optical sheet comprising a first surface and a second surface opposite to the first surface, wherein, The optical sheet comprises a substrate and a functional layer sequentially from the second surface toward the first surface. The functional layer comprises adhesive components and metal oxide particles. The average area of ​​the Voronoi region, with the metal oxide particles observed on the first surface as the parent point, is 2500 nm. 2 above.

[0034] <2>

[0035] according to <1> The optical sheet, wherein the average area of ​​the Voronoi region is 3200 nm. 2 above.

[0036] <3>

[0037] according to <1> or <2> The optical sheet, wherein the standard deviation of the area of ​​the Voronoi region is 950 nm. 2 above.

[0038] <4>

[0039] according to <1> ~ <3> The optical sheet in any one of the following embodiments, wherein the standard deviation of the area of ​​the Voronoi region is greater than or equal to the average area of ​​the Voronoi region.

[0040] <5>

[0041] according to <1> ~ <4> The optical sheet described in any one of the following statements, wherein, Use TABER's "Jumbo Wearaser (registered trademark) CS-6" as the sliding piece. The coefficient of kinetic friction between the first surface and the sliding plate to which a load of 200g is applied is less than 0.95.

[0042] <6>

[0043] according to <1> ~ <5> The optical sheet described in any one of the following statements, wherein, The optical sheet is resistant to abrasion resistance tests conducted on the first surface using steel wool under the following conditions.

[0044] Abrasion resistance test: Using steel wool #0000 as the sliding plate, the test was repeated 1000 times with a load of 1000g, a moving speed of 80mm / second, and a single-pass moving distance of 40mm.

[0045] <7>

[0046] according to <1> to <6> The optical sheet described in any one of the following statements, wherein, The optical sheet is resistant to abrasion resistance tests conducted on the first surface using rubber under the following conditions.

[0047] Abrasion resistance test: Using the "Jumbo Wearaser (registered trademark), model: CS-6" manufactured by TABER as the sliding pad, the test was performed 150 times with a load of 200g, a moving speed of 200mm / second, and a single-pass moving distance of 50mm.

[0048] <8>

[0049] according to <1> ~ <7> The optical sheet according to any one of the following methods, wherein the functional layer comprises hollow silica particles.

[0050] <9>

[0051] according to <1> ~ <8> The optical sheet according to any one of the following, wherein the functional layer comprises alumina particles.

[0052] <10>

[0053] according to <1> ~ <9> The optical sheet according to any one of the following methods, wherein the functional layer comprises a siloxane compound.

[0054] <11>

[0055] according to <1> ~ <10> The optical sheet according to any one of the following methods, wherein the functional layer comprises a cured product of a composition containing a UV-curable siloxane compound.

[0056] <12>

[0057] according to <1> ~ <11> The optical sheet according to any one of the following methods, wherein the thickness of the functional layer is more than 60 nm and less than 120 nm.

[0058] <13>

[0059] according to <1> ~ <12> The optical sheet according to any one of the following has a resin layer located between the substrate and the functional layer, the resin layer comprising a cured product of a curable resin composition.

[0060] <14>

[0061] A type of item that has multiple <1> ~ <13> The optical sheet as described in any one of the following.

[0062] <15>

[0063] according to <14> The sheet-like article is wound around a winding axis.

[0064] <16>

[0065] A polarizer includes a first protective film, a polarizer, and a second protective film, wherein at least one of the first protective film and the second protective film comprises <1> ~ <13> The optical sheet as described in any one of the following.

[0066] <17>

[0067] A display device includes: an image forming apparatus; and an image forming device overlapping the image forming apparatus. <1> ~ <13> The optical sheet as described in any one of the following.

[0068] <18>

[0069] A panel comprising: an article to be joined; and an element engaged with said article to be joined. <1> ~ <13> The optical sheet as described in any one of the following.

[0070] <19>

[0071] A method for selecting an optical sheet, comprising: For an optical sheet, the step of measuring the average area of ​​a Voronoi region with metal oxide particles observed on a first surface as mother points, the optical sheet having a first surface and a second surface opposite the first surface, and having a substrate and a functional layer sequentially disposed from the second surface toward the first surface, the functional layer comprising an adhesive component and metal oxide particles; and The average area (nm) of the selected Voronoi region was selected. 2 The step of using an optical sheet with a specified value or higher.

[0072] <20>

[0073] A method for manufacturing an optical sheet, comprising: The steps of manufacturing an optical sheet include: the optical sheet having a first surface and a second surface opposite to the first surface; a substrate and a functional layer being sequentially formed from the second surface toward the first surface; the functional layer comprising an adhesive component and metal oxide particles; and... The average area (nm) of the Voronoi region, selected with the metal oxide particles observed on the first surface as the parent point, was chosen. 2 The step of using an optical sheet with a specified value or higher.

[0074] The following is a detailed description of one embodiment of this disclosure. In the accompanying drawings, for ease of illustration and understanding, the scale and aspect ratios relative to the actual object have been appropriately altered and exaggerated.

[0075] In this manual, the terms "sheet," "film," and "plate" are used interchangeably only for different names. For example, "optical sheet" is not different from components called optical film or optical plate, just because of the different names used.

[0076] In this specification, multiple candidates for upper limits and multiple candidates for lower limits related to a numerical range are sometimes stated in different statements. In these statements, the numerical range can also be constructed by combining any candidate for an upper limit and any candidate for a lower limit. As an example, let's discuss "Parameter B can be above A1, above A2, or above A3. Parameter B can be below A4, below A5, or below A6." In this example, the numerical range of parameter B can be above A1 and below A4, above A1 and below A5, above A1 and below A6, above A2 and below A4, above A2 and below A5, above A2 and below A6, above A3 and below A4, above A3 and below A5, or above A3 and below A6.

[0077] To clarify directional relationships between figures, a common direction is indicated by an arrow labeled with a common reference numeral in several figures. The side with the tip of the arrow becomes the first side of each direction. The side opposite to the tip of the arrow becomes the second side of each direction. For example... Figure 1 As shown, an arrow pointing inwards toward the paper in a direction perpendicular to the paper surface is represented by an "×" symbol placed inside the circle.

[0078] <<<Optical Plate 10>>>

[0079] like Figure 1 As shown, the optical sheet 10 of this embodiment includes a first surface 11 and a second surface 12. The optical sheet 10 includes a substrate 20 and a functional layer 40 in order from the second surface 12 to the first surface 11. The functional layer 40 contains an adhesive component 41 and metal oxide particles 42. The functional layer 40 is capable of performing functions corresponding to the metal oxide particles 42. The functional layer 40 can be one or more of a low-reflection layer or a reflection suppression layer, an antifouling layer, a hard coating layer, and an antistatic layer.

[0080] As an example, the functional layer 40 may contain hollow silica particles 43 as metal oxide particles 42. The hollow silica particles 43 are silica particles with pores. The hollow silica particles 43 have a hollow structure. Due to their structure, the hollow silica particles 43 have a low refractive index. The functional layer 40, containing hollow silica particles 43 as metal oxide particles 42, has a lower refractive index than the binder component 41. Based on the low refractive index functional layer 40, reflection at the first surface 11 can be suppressed. The low refractive index functional layer 40 functions as a low-reflection layer or a reflection suppression layer.

[0081] In the use of optical sheets, external forces are applied. For example, the optical sheet may be rubbed. If external forces are applied to the optical sheet, metal oxide particles may detach from the functional layer. When external forces are applied to the optical sheet, the metal oxide particles may deform. With the detachment or deformation of the metal oxide particles, defects such as scratches can easily occur on the surface of the optical sheet. The thickness of the functional layer is usually thinner than the thickness of the substrate. If external forces are applied to the optical sheet, the functional layer may peel off from the optical sheet. The scratch resistance of optical sheets with functional layers is easily reduced.

[0082] For functional layers containing hollow silica particles as metal oxide particles, these particles tend to detach from the functional layer during the use of optical sheets. Due to their porous nature, these hollow silica particles are easily crushed. As the particles detach or deform, scratches and other defects easily appear on the surface of the optical sheet. The thickness of the functional layer, serving as a low-refractive-index layer or a reflection-suppressing layer, is approximately 100 nm. This layer is easily peeled off and damaged. Optical sheets containing hollow silica particles have poor scratch resistance.

[0083] <<Average area of ​​the Voronoi region>>

[0084] In the optical sheet 10 of this embodiment, the average area of ​​the Voronoi region, with the metal oxide particles 42 observed on the first surface 11 as the parent point, is 2500 nm. 2 The above. The average area of ​​the Voronoi region, with the metal oxide particles 42 observed on the first surface 11 as the parent point, is 2500 nm. 2 The optical sheet 10 of this embodiment described above has excellent scratch resistance on its first surface 11. The average area of ​​the Voronoi region, with the hollow silica particles 42 observed on the first surface 11 as parent points, is 2500 nm. 2 The optical sheet 10 described above has a first surface 11 that exhibits stable and excellent scratch resistance. The detailed reasons for the improved scratch resistance are not yet clear, but it is speculated that the following factors contribute to this improvement. However, this disclosure is not limited to these assumptions.

[0085] like Figure 2 As shown, the Voronoi region 80 is a region defined by the Voronoi boundary 80L. A Voronoi region 80 is defined for each parent point 80C. For example... Figure 2As shown, the Voronoi boundary 80L is the bisecting line of two parent points 80C. The Voronoi boundary 80L, as the bisecting line of the two parent points 80C, is orthogonal to the straight line 80CL connecting the two parent points 80C. The two parent points 80C that define a Voronoi boundary 80L are the parent points 80C corresponding to the two Voronoi regions 80 divided by that Voronoi boundary 80L. The intersection of the Voronoi boundaries 80L is the Voronoi point 80P. A Voronoi point 80P is the boundary point of three or more Voronoi regions 80. The distance from the three or more parent points 80C corresponding to the three or more Voronoi regions 80 to the Voronoi region 80P is the same.

[0086] Figures 9A to 9G The Voronoi diagram is shown. A Voronoi diagram is a diagram that divides a planar region into each Voronoi region 80 corresponding to each parent point 80C. In essence, a Voronoi diagram can be described as a diagram that divides a plane with multiple parent points 80C distributed among them according to the nearest parent point 80C.

[0087] The average area of ​​the Voronoi region is an indicator of the density of metal oxide particles 42 located on the first surface 11. Setting a lower limit for the average area of ​​the Voronoi region indicates that the metal oxide particles 42, acting as parent points, are sparsely located on the first surface 11. In order to impart certain functions to the functional layer 40, the functional layer 40 needs to contain metal oxide particles 42 in a specified amount or proportion. By limiting the amount of metal oxide particles 42 appearing on the first surface 11 under this constraint, the adhesion between the adhesive component 41 and the metal oxide particles 42 near the first surface 11, and the surface condition of the first surface 11, can be improved. As a result, it is presumed that the scratch resistance of the first surface 11 composed of the functional layer 40 is enhanced.

[0088] In Patent Document 1 (WO2021 / 020504) mentioned above, inorganic oxide particles are used to form protrusions on the surface. The metal oxide particles in Patent Document 1 are intended to protect the hollow silica particles by forming protrusions on the surface. In this embodiment, metal oxide particles 42 are used to achieve a significantly different effect than those in Patent Document 1. The optical sheet 10 of this embodiment also has a significantly different surface shape than that of Patent Document 1, and achieves exceptionally superior scratch resistance compared to Patent Document 1. In this respect, the effect of this embodiment is a significant effect that far exceeds the range predicted based on the level of technology at the time of this application.

[0089] As mentioned above, the average area of ​​the Voronoi region can be 2500 nm. 2 The above can be further extended to 2900nm. 2 The above can be for 3000nm 2 The above can be for 3200nm2 The above can be for 3500nm 2 The above can be for 3600nm 2 above.

[0090] The upper limit of the average area of ​​the Voronoi region does not need to be specifically set. From the viewpoint of enhancing the function of the functional layer 40 caused by the metal oxide particles 42, an upper limit of the average area of ​​the Voronoi region can be set. The average area of ​​the Voronoi region can be 7000 nm. 2 The following can be 6000nm 2 The following can be 5000nm 2 The following can also be 4900nm 2 the following.

[0091] The average area of ​​the Voronoi region can be 2500 nm. 2 The above 7000nm 2 The following can be 2900nm 2 The above 7000nm 2 The following can be 3000nm 2 The above 7000nm 2 The following can be 3200nm 2 The above 7000nm 2 The following can be 3500nm 2 The above 7000nm 2 The following can be 3600nm 2 The above 7000nm 2 The average area of ​​the Voronoi region is 2500 nm. 2 The above 6000nm 2 The following can be 2900nm 2 The above 6000nm 2 The following can be 3000nm 2 The above 6000nm 2 The following can be 3200nm 2 The above 6000nm 2 The following can be 3500nm 2 The above 6000nm 2 The following can be 3600nm 2 The above 6000nm 2 The average area of ​​the Voronoi region is 2500 nm. 2 Above 5000nm 2 The following can be 2900nm 2 Above 5000nm 2 The following can be 3000nm 2Above 5000nm 2 The following can be 3200nm 2 Above 5000nm 2 The following can be 3500nm 2 Above 5000nm 2 The following can be 3600nm 2 Above 5000nm 2 The average area of ​​the Voronoi region is 2500 nm. 2 Above 4900nm 2 The following can be 2900nm 2 Above 4900nm 2 The following can be 3000nm 2 Above 4900nm 2 The following can be 3200nm 2 Above 4900nm 2 The following can be 3500nm 2 Above 4900nm 2 The following can also be 3600nm 2 Above 4900nm 2 the following.

[0092] <Method for calculating the average area of ​​the Voronoi region>

[0093] The average area of ​​the Voronoi region is determined by the following steps. The steps for obtaining the average area of ​​the Voronoi region include: obtaining an observation image of the first surface 11; determining a generatrix from the observation image; and determining the area of ​​the Voronoi region by determining the Voronoi region from the generatrix.

[0094] (Steps to obtain the first observation image)

[0095] The following steps are performed to obtain an observation image of the first surface. A 5mm × 5mm sample is cut from the optical slide 10, which is to be evaluated. Conductive double-sided tape is applied to the entire area of ​​the sample surface corresponding to the second surface 12 of the optical slide 10. Then, the conductive double-sided tape applied to the sample is attached to a flat sample stage. Thus, the sample is fixed to the flat sample stage using conductive double-sided tape. The flat sample stage is an accessory of a scanning electron microscope (SEM) used for sample observation. The conductive double-sided tape is not particularly limited. The conductive double-sided tape can be a carbon ribbon for SEM using an aluminum substrate manufactured by Nisshin EM Co., Ltd.

[0096] Apply carbon paste to the four corners of the sample, which is fixed to the flat sample stage. There are no particular limitations on the carbon paste. The carbon paste can be Colloidal Graphite No. 7141 (solvent: isopropanol) manufactured by Nisshin EM Co., Ltd.

[0097] Next, a PtPd vapor-deposited film was formed on the sample using an ion sputtering apparatus. The ion sputtering conditions were as follows: Ar gas was introduced into the chamber containing the sample.

[0098] Target: PtPd

[0099] Vacuum degree: 8Pa

[0100] • Discharge current value: 15mA

[0101] Evaporation time: 15 seconds

[0102] After the vapor-deposited film is formed, a standard sample stage with the sample fixed on it is mounted on the standard sample holder of a scanning electron microscope. The observation conditions of the scanning electron microscope are as follows, and an observation image of the sample surface corresponding to the first surface 11 of the optical slide 10, which is the object of evaluation, is obtained. The scanning electron microscope used is a Hitachi High-Tech SU-9000 ultra-high resolution field emission scanning electron microscope. Figure 8A An example of observing an image is shown.

[0103] • Measurement mode: SE

[0104] Accelerating voltage: 1.0kV

[0105] • Transmit current: 10μA

[0106] • WD (working distance): 3mm or more but less than 3.5mm

[0107] • Lens mode: High

[0108] • Observation ratio: 25,000x

[0109] • Data Size: 1280 pixels × 960 pixels

[0110] • Pixel Size: 3.96875nm

[0111] (Steps for determining the mother point from observed images)

[0112] The steps for determining the mother point based on the observed images obtained above are as follows: Remove unnecessary parts such as the scale bar from the observed images, excluding the sample image. By deleting the unnecessary parts, image data for image processing is obtained.

[0113] Next, the image data is binarized. Through binarization, the bright areas of the image data become white areas, and the dark areas become black areas. This results in an image with circular white areas scattered within a black background. The white areas roughly appear at the locations where the metal oxide particles 42 are present.

[0114] In binarization processing, ImageJ and Fiji are used as image processing software. ImageJ is an open-source image processing software developed by the National Institutes of Health in the United States and is in the public domain. Fiji is a plugin for ImageJ. The following commands use Fiji in binarization processing. Under the following conditions, the white portion is independently generated in each metal oxide particle observed independently in the microscope image. Figure 8B Indicates to Figure 8A The image after binarization.

[0115] Noise Removal: Despeckle

[0116] • Binarization: AutoLocal Threshold(Metod=Midgray, Radius=50)

[0117] Noise Removal: Open

[0118] • Hole filling in the black area: FillHoles

[0119] • Separation of the white portion: Watershed

[0120] (Steps for determining the area of ​​the Voronoi region)

[0121] The following steps are performed to determine the area of ​​the Voronoi region. By processing the binarized image data, the coordinates representing the centroid positions of each white portion of the metal oxide particles are determined. A binary image is generated, with one pixel at the centroid coordinate of each white portion set to white and the others set to a black background. Fiji's Analyse Perticles function is used in the generation of the binary image. Figure 8C Based on Figure 8B The binary image generated from the image.

[0122] A Voronoi map is created by further processing the resulting binary image. The Voronoi map is generated using the centroid of the metal oxide particles as the parent point. The average area of ​​the Voronoi regions is calculated from the created Voronoi map. Fiji's Voronoi command is used to create the Voronoi map and calculate the average area of ​​the Voronoi regions. The average area of ​​the Voronoi regions is calculated as the average area of ​​the Voronoi regions contained in the image.

[0123] The calculated value is used as the average area of ​​the Voronoi region, with the metal oxide particles 42 observed on the first surface 11 as the parent point. The calculated average area of ​​the Voronoi region is compared with a predetermined value, and the optical sheet 10 is evaluated based on the average area of ​​the Voronoi region.

[0124] <<Standard Deviation of Area of ​​the Voronoi Region>>

[0125] By adjusting the area of ​​the Voronoi region, excellent scratch resistance can be imparted to the first surface 11 of the optical plate 10. A lower and upper limit can also be set for the standard deviation of the Voronoi region's area. By combining this with the numerical range of the average area of ​​the Voronoi region, setting a lower and upper limit for the standard deviation of the Voronoi region's area allows for consistently excellent scratch resistance to be imparted to the entire area of ​​the first surface 11. Similarly, a lower and upper limit can be set for the ratio of the standard deviation of the Voronoi region's area to the average area of ​​the Voronoi region, i.e., the coefficient of variation. By combining this with the numerical range of the average area of ​​the Voronoi region, setting a lower and upper limit for the coefficient of variation allows for consistently excellent scratch resistance to be imparted to the entire area of ​​the first surface 11.

[0126] The standard deviation of the area of ​​the Voronoi region can be 950 nm. 2 The above can be for 1000nm 2 The above can be for 1041nm 2 The above can be for 1056nm 2 The above can be for 1114nm 2 The above can be for 1191nm 2 The ratio of the standard deviation of the area of ​​the Voronoi region to the average area of ​​the Voronoi region, i.e., the coefficient of variation, can be greater than 0.30, greater than 0.34, or greater than 0.35.

[0127] The standard deviation of the area of ​​the Voronoi region can be 2200 nm. 2 The following can be 2110nm 2 The following can be 1890nm 2 The following can be 1775nm 2 The following can be 1754nm 2 The ratio of the standard deviation of the area of ​​the Voronoi region to the average area of ​​the Voronoi region can be less than 0.50, less than 0.47, less than 0.45, or less than 0.42.

[0128] The standard deviation of the area of ​​the Voronoi region can be 950 nm. 2 The above 2200nm 2The following can be 1000nm 2 The above 2200nm 2 The following can be 1041nm 2 The above 2200nm 2 The following can be 1056nm 2 The above 2200nm 2 The following can be 1114nm 2 The above 2200nm 2 The following can be 1191nm 2 The above 2200nm 2 The standard deviation of the area of ​​the Voronoi region is 950 nm. 2 The above 2110nm 2 The following can be 1000nm 2 The above 2110nm 2 The following can be 1041nm 2 The above 2110nm 2 The following can be 1056nm 2 The above 2110nm 2 The following can be 1114nm 2 The above 2110nm 2 The following can be 1191nm 2 The above 2110nm 2 The standard deviation of the area of ​​the Voronoi region is 950 nm. 2 The above 1890nm 2 The following can be 1000nm 2 The above 1890nm 2 The following can be 1041nm 2 The above 1890nm 2 The following can be 1056nm 2 The above 1890nm 2 The following can be 1114nm 2 The above 1890nm 2 The following can be 1191nm 2 The above 1890nm 2 The standard deviation of the area of ​​the Voronoi region is 950 nm. 2 The above 1775nm 2 The following can be 1000nm 2 The above 1775nm 2 The following can be 1041nm 2 The above 1775nm 2 The following can be 1056nm 2 The above 1775nm2 The following can be 1114nm 2 The above 1775nm 2 The following can be 1191nm 2 The above 1775nm 2 The standard deviation of the area of ​​the Voronoi region is 950 nm. 2 The above can be for 1000nm 2 The above 1754nm 2 The following can be 1041nm 2 The above 1754nm 2 The following can be 1056nm 2 The above 1754nm 2 The following can be 1114nm 2 The above 1754nm 2 The following can be 1191nm 2 The above 1754nm 2 the following.

[0129] The ratio of the standard deviation of the area of ​​the Voronoi region to the average area of ​​the Voronoi region, i.e., the coefficient of variation, can be greater than or less than 0.30 and less than 0.50, greater than or less than 0.34 and less than 0.50, or greater than or less than 0.35 and less than 0.50. The coefficient of variation can be greater than or less than 0.30 and less than 0.47, greater than or less than 0.34 and less than 0.47, or greater than or less than 0.35 and less than 0.47. The coefficient of variation can be greater than or less than 0.30 and less than 0.45, greater than or less than 0.34 and less than 0.45, or greater than or less than 0.35 and less than 0.45. The coefficient of variation can be greater than or less than 0.30 and less than 0.42, greater than or less than 0.34 and less than 0.42, or greater than or less than 0.35 and less than 0.42.

[0130] As demonstrated in the embodiments described later, by setting the standard deviation of the area of ​​the Voronoi region to 1450 nm 2 Above and 2150nm 2 The following is further set to 1458nm 2 Above and 2110nm 2 The following methods can improve the abrasion resistance of steel wool. This is achieved by setting the standard deviation of the area of ​​the Voronoi region to 1450 nm. 2 The above 1800nm 2 The following is further set to 1458nm 2 The above 1775nm 2 The following can improve the abrasion resistance of rubber.

[0131] As demonstrated in the examples described later, the abrasion resistance to steel wool can be improved by setting the coefficient of variation of the area of ​​the Voronoi region to 0.38 or higher. The abrasion resistance to rubber can be improved by setting the coefficient of variation of the area of ​​the Voronoi region to 0.40 or higher.

[0132] <<Abrasion Resistance Test>>>

[0133] The optical sheet 10, with its average area adjusted in the Voronoi region, exhibits excellent scratch resistance. In a scratch resistance test using steel wool on the first surface 11, the optical sheet 10 demonstrates high resistance. In a scratch resistance test using rubber on the first surface 11, the optical sheet 10 also exhibits high resistance.

[0134] <Steel wool abrasion resistance>

[0135] The steel wool abrasion resistance test is an indicator of its resistance to defects such as scratches that occur when steel wool is pressed against a test sample and moved relative to it. The optical plate 10 is resistant to the steel wool abrasion resistance test performed under the conditions described below.

[0136] The test sample for the optical film being evaluated is rectangular. The shorter side of the rectangle is set to 50mm, and the longer side to 100mm. The sample is visually confirmed to be free of dust, scratches, or other abnormalities. The rectangular sample is then unfolded horizontally on the testing machine in a manner that prevents wrinkles and warping. Repair tape is used to secure the four corners of the unfolded sample to the testing machine. The repair tape can be 3M product, trade name "810-3-18".

[0137] The steel wool, serving as a sliding plate, is brought into contact with the surface of the sample, which is formed by the first surface of the optical plate. The steel wool is "BONSTAR B-204" manufactured by Japan Steel Wool Co., Ltd., serial number #0000. Bonstar B-204 has a business-grade size of approximately 390 mm in width, approximately 75 mm in height, and approximately 110 mm in thickness. The contact area between the test sample and the sliding plate is 20 mm × 20 mm. A load of 1000 g is applied to the sliding plate from above in the vertical direction, pressing the sliding plate against the test sample, which is unfolded along the horizontal plane.

[0138] With the sliding plate pressed against the test sample from above in the vertical direction, the sliding plate and the sample are moved relative to each other in the horizontal direction. The relative movement is a reciprocating motion along a straight path. The cycle of the reciprocating motion is 1000 times. The speed of the reciprocating motion is set to 80 mm / s. The stroke of the reciprocating motion is 40 mm in both the outward and return directions. The reciprocating motion is parallel to the long side of the sample.

[0139] The test environment is set to a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The test samples are conditioned in the test environment for 16 hours before the start of the test.

[0140] The sliding sheet is an unused product. Before conducting the test on the evaluation object, the preparation sample is wiped with steel wool to perform the pre-treatment of the steel wool. The testing machine used in the test of the sample to be evaluated is also used for the pre-treatment of the steel wool. The preparation sample is a polyethylene terephthalate film. The preparation sample is in a rectangular shape with a short side of 50 mm and a long side of 100 mm. The steel wool is rubbed on the untreated surface of the polyethylene terephthalate film. The preparation sample is unfolded along the horizontal plane, and the four corners of the preparation sample are fixed to the testing machine with repair tape. The steel wool is pressed against the preparation sample from above in the vertical direction. The contact area between the preparation sample and the steel wool is 20 mm × 20 mm. The load for pressing the steel wool against the preparation sample is set to 300 g. The steel wool pressed against the preparation sample is relatively moved horizontally with respect to the preparation sample. The steel wool and the preparation sample are relatively moved in a direction parallel to the direction in which the fibers of the steel wool mainly extend. The relative movement is a reciprocating motion. The period of the reciprocating motion is set to 300 times. The speed of the reciprocating motion is set to 80 mm / second. The stroke of the reciprocating motion is 40 mm both in the forward and return strokes. Thus, the steel wool pressed against the preparation sample is used for the test of the evaluation object.

[0141] After the abrasion resistance test, the surface of the test sample formed by the first surface of the optical sheet is observed with the naked eye. The observation distance is 30 cm. The illuminance on the surface of the sample to be observed is set to be 800 Lx or more and 1200 Lx or less.

[0142] In the case where defects such as scratches that would be a problem when applied to a display device are observed in the test sample, it is determined that the test sample of the optical sheet 10 as the evaluation object does not have resistance to the abrasion resistance test using steel wool on the first surface 11. The abrasion resistance test is performed 5 times on the optical sheet 10 as one evaluation object. In the case where no defects of a degree that would be a problem when applied to a display device are generated in all 5 tests, it is judged that the optical sheet 10 as the evaluation object has resistance to the abrasion resistance test using steel wool on the first surface 11. The defects of a degree that would be a problem when applied to a display device refer to the defects corresponding to the evaluation "4" or "5" in the 6 - level evaluation of "0" to "5" described in the following examples. In the 5 tests, the steel wool is replaced each time. The above-mentioned pre-treatment of the steel wool is performed before the start of the test in each of the 5 tests.

[0143] <CS6 Resistance>

[0144] The rubber abrasion resistance test is an indicator of resistance to defects such as damage that occur when rubber is pressed against a test sample used as the evaluation object and moved relative to it. The optical plate 10 is resistant to abrasion resistance tests under the following conditions using "JumboWeaser CS-6" (registered trademark) manufactured by TABER Corporation as the sliding plate.

[0145] The test sample for the optical film being evaluated is rectangular. The shorter side of the rectangle is set to 50mm, and the longer side to 100mm. The sample is visually confirmed to be free of dust, scratches, or other abnormalities. The rectangular sample is then unfolded horizontally on the testing machine in a manner that prevents wrinkles and warping. Repair tape is used to secure the four corners of the unfolded sample to the testing machine. The repair tape can be 3M product, trade name "810-3-18".

[0146] The sliding plate of "Jumbo Wearaser CS-6 (registered trademark)" is primarily composed of rubber. The CS-6 sliding plate is approximately cylindrical in shape. The cylindrical front face of the sliding plate is brought into contact with the surface of a sample formed by the first surface of the optical plate. The contact area between the test sample and the sliding plate is a circle with a diameter of 12 mm.

[0147] The CS-6, serving as a sliding piece, is held by a retainer. The retainer is fixed to the cylindrical side of the sliding piece. The cylindrical front end face of the CS-6, held by the retainer, protrudes 2 mm from the retainer. By limiting the protruding length of the CS-6 from the retainer, the deformation of the CS-6 during testing is limited. The sliding piece, held by the retainer, is pressed vertically upwards onto the test sample, which is unfolded along a horizontal plane. The load applied to the test sample by pressing the sliding piece is set to 200g.

[0148] With the sliding plate pressed against the test sample from above in the vertical direction, the sliding plate and the sample move relative to each other in the horizontal direction. This relative movement is a reciprocating motion. The cycle of the reciprocating motion is 150 times. The speed of the reciprocating motion is 200 mm / s. The stroke of the reciprocating motion is 50 mm in both the outward and return directions. The reciprocating motion is parallel to the long side of the sample.

[0149] The test environment was set at a temperature of 23℃±2℃ and a relative humidity of 50%±5%. The test samples were prepared in the test environment for 16 hours before the start of the test.

[0150] Before testing the evaluation object, the sample was wiped with CS-6 as a pretreatment. The testing machine used for testing the sample was also used for CS-6 pretreatment. The sample was a "single-sided easy-bond type: A4160" manufactured by Toyobo Co., Ltd. The sample was unfolded horizontally, and the four corners of the untreated (exposed PET) side of the sample were fixed to the testing machine with repair tape. The CS-6 was pressed against the sample from the top vertically. The contact area between the sample and the CS-6 was a circle with a diameter of 12 mm. The load of the CS-6 pressing against the sample was set to 600 g. The CS-6 was moved horizontally relative to the sample. The relative movement was a reciprocating motion. The cycle of the reciprocating motion was set to 150 times. The speed of the reciprocating motion was 220 mm / s. The stroke of the reciprocating motion was 50 mm in both the outward and return directions. Thus, the CS-6 sample is pressed onto the test object to be evaluated. After confirming that the pressed CS-6 surface is free of rubber debris and is flat, the test is carried out.

[0151] After the scratch resistance test, the surface of the test sample, consisting of the first side of the optical sheet, was observed with the naked eye. The observation distance was 30 cm. The illuminance on the surface of the sample being observed was set to be above 800 Lx and below 1200 Lx.

[0152] If defects such as scratches that would cause problems when applied to a display device are observed in the test sample, the test sample of the optical sheet 10, which is the object of evaluation, is determined to be unresistant to the scratch resistance test of the first surface 11 with CS-6 as the sliding sheet. Five scratch resistance tests are performed on the optical sheet 10, which is the object of evaluation. If no defects that would cause problems when applied to a display device occur in the five tests, the optical sheet 10, which is the object of evaluation, is determined to be resistant to the scratch resistance test of the first surface 11 with CS-6 as the sliding sheet. Defects that would cause problems when applied to a display device refer to defects corresponding to rating "4" or "5" in the six-level evaluation system of "0" to "5" described in the embodiments described later. The same CS-6 is used in the five tests. The pretreatment of CS-6 described above is performed before the start of each of the five tests.

[0153] <<Coefficient of kinetic friction>>

[0154] An upper limit can also be set for the coefficient of kinetic friction of the first surface 11. By setting an upper limit for the coefficient of kinetic friction of the first surface 11, the sliding properties of the first surface 11 are improved, thereby improving scratch resistance. The coefficient of kinetic friction of the first surface 11 can be below 0.95, below 0.93, below 0.91, below 0.90, below 0.85, below 0.80, below 0.78, below 0.75, or below 0.70.

[0155] The lower limit of the kinetic friction coefficient of the first surface 11 is not specifically set. The kinetic friction coefficient of the first surface 11 can be above 0, greater than 0, above 0.50, or above 0.60.

[0156] The coefficient of kinetic friction of the first surface 11 can be greater than 0 and less than 0.95, greater than 0 and less than 0.93, greater than 0 and less than 0.91, greater than 0 and less than 0.90, greater than 0 and less than 0.85, greater than 0 and less than 0.80, greater than 0 and less than 0.78, greater than 0 and less than 0.75, or greater than 0 and less than 0.70. The coefficient of kinetic friction of the first surface 11 can also be greater than 0 and less than 0.95, greater than 0 and less than 0.93, greater than 0 and less than 0.91, greater than 0 and less than 0.90, greater than 0 and less than 0.85, greater than 0 and less than 0.80, greater than 0 and less than 0.78, greater than 0 and less than 0.75, or greater than 0 and less than 0.70. The coefficient of kinetic friction of the first surface 11 can be greater than 0.50 and less than 0.95, greater than 0.50 and less than 0.93, greater than 0.50 and less than 0.91, greater than 0.50 and less than 0.90, greater than 0.50 and less than 0.85, greater than 0.50 and less than 0.80, greater than 0.50 and less than 0.78, greater than 0.50 and less than 0.75, or greater than 0.50 and less than 0.70. The coefficient of kinetic friction of the first surface 11 can be greater than or equal to 0.60 and less than 0.95, greater than or equal to 0.60 and less than 0.93, greater than or equal to 0.60 and less than 0.91, greater than or equal to 0.60 and less than 0.90, greater than or equal to 0.60 and less than 0.85, greater than or equal to 0.60 and less than 0.80, greater than or equal to 0.60 and less than 0.78, greater than or equal to 0.60 and less than 0.75, or greater than or equal to 0.60 and less than 0.70.

[0157] Test samples were cut from the optical sheet to be measured, and the coefficient of kinetic friction was determined as the average of 20 measured values ​​of the coefficient of kinetic friction obtained for the test sample. The test sample was visually confirmed to be free of dust, scratches, or other abnormalities. The coefficient of kinetic friction of the test sample was measured as follows.

[0158] The test sample of the optical sheet is fixed to the device for measuring the coefficient of kinetic friction as described below. First, the test sample is unfolded on the worktable, which serves as the sample fixing stage, in a manner that prevents wrinkles, warping, etc. The worktable is unfolded along a horizontal plane. The size of the test sample is 15cm × 25cm. The four corners of the unfolded test sample are fixed to the worktable with repair tape. The repair tape can be 3M product, trade name "810-3-18". For the test sample of the optical sheet fixed to the worktable, the second side is in contact with the worktable, and the first side faces the opposite side of the worktable.

[0159] Next, a sliding piece is prepared to be used to determine the coefficient of friction between the sliding piece and the first surface 11. The sliding piece is a Jumbo Wearaser CS-6 (registered trademark) manufactured by TABER. The main component of CS-6 is rubber. The CS-6 sliding piece, as in the aforementioned abrasion resistance test using CS-6 as the sliding piece, is held by a retainer. The sliding piece, held by the retainer, is pressed vertically upwards onto the test sample, which is spread out along a horizontal plane. The sliding piece is brought into contact with the first surface of the test sample. The contact surface between the sliding piece and the test sample is a circle with a diameter of 12 mm. The contact surface extends horizontally. A counterweight is attached to the retainer using double-sided tape. The load on which the sliding piece is pressed against the sample is set to 200 g. A nylon thread can be attached to the retainer.

[0160] With a 200g load applied, the sliding plate is pressed vertically against the first surface of the test sample, and then moved horizontally. The sliding plate, along with the retainer and counterweight, is moved horizontally by pulling a nylon line connected to the retainer via a hook. The sliding plate moves along the long side of the sample. The sliding plate moves at a speed of 15 mm / s. The stroke of the sliding plate is set to 5 cm. During one stroke of the sliding plate, the horizontal dynamic friction force acting on the sliding plate is measured every 0.01 seconds. The coefficient of dynamic friction is obtained by dividing the average of the measured dynamic friction force by the pressing load (200g) applied to the sliding plate towards the sample.

[0161] The test environment was set at a temperature of 23℃±2℃ and a relative humidity of 50%±5%. The test samples were prepared in the test environment for 16 hours before the start of the test.

[0162] Before conducting tests on the evaluation object, CS-6 is rubbed on the prepared sample as a CS-6 pretreatment. The CS-6 pretreatment in the dynamic friction coefficient evaluation test is performed in the same way as the pretreatment in the scratch resistance test using CS-6 as the sliding sheet. Twenty measurements are performed on one test sample. The average value of the dynamic friction coefficient measured in the 20 tests is taken as the value of the dynamic friction coefficient of the evaluation object. The same CS-6 is used in the 20 tests on the evaluation object. The CS-6 pretreatment is performed separately in each of the 20 tests.

[0163] Regarding the coefficient of kinetic friction, conditions other than those mentioned above were determined according to JIS K7125:1999.

[0164] <<Average particle size of metal oxide particles>>

[0165] An upper limit can be set for the average particle size of the metal oxide particles 42 contained in the functional layer 40. By setting a combination of the lower limit of the average area of ​​the aforementioned Voronoi region and the upper limit of the average particle size, the dispersion state of the metal oxide particles 42 in the first surface 11 can be controlled more effectively. The adhesion between the adhesive component 41 and the metal oxide particles 42 near the first surface 11 and the surface condition of the first surface 11 are improved, which can effectively improve the scratch resistance of the first surface 11.

[0166] The average particle size of the metal oxide particles 42 can be smaller than the average thickness of the functional layer 40. The average particle size of the metal oxide particles 42 can be less than 80% of the average thickness of the functional layer 40, 75% of the average thickness of the functional layer 40, 70% of the average thickness of the functional layer 40, 60% of the average thickness of the functional layer 40, or 50% of the average thickness of the functional layer 40.

[0167] When the functional layer 40 functions as a low-reflection layer or a reflection suppression layer, the thickness of the functional layer 40 can be relatively thin, and the functional layer 40 can contain hollow silica particles 43 as metal oxide particles. The hollow silica particles 43 typically have a larger average particle size than other particles contained in the functional layer 40. In this example, the surface condition of the first surface 11 depends significantly on the relationship between the average thickness of the functional layer 40 and the average particle size of the hollow silica particles 43. In this example, an upper limit can be set for the average particle size of the hollow silica particles 43. By combining the lower limit of the average area of ​​the Voronoi region with the upper limit of the average particle size of the hollow silica particles 43, the scratch resistance of the first surface 11 can be improved more effectively.

[0168] The average particle size of the hollow silica particles 43 can be smaller than the average thickness of the functional layer 40. The average particle size of the hollow silica particles 43 can be less than 80%, less than 75%, less than 70%, less than 60%, or less than 50% of the average thickness of the functional layer 40.

[0169] The “average particle size” used for particles such as metal oxide particles 42 and hollow silica particles 43 is a value determined by the following (1) to (3). Particles may sometimes aggregate, but the average particle size is the average primary particle size.

[0170] (1) Observe the cross section of the optical sheet containing particles using a transmission electron microscope (TEM) and obtain the observation image by taking pictures.

[0171] (2) Extract any 10 particles from the observed image and determine the particle size of each particle. The particle size (nm) is the distance between the two lines that maximize the distance between them when the cross-section of the particle is held between any two parallel lines. That is, the particle size is the maximum length of the particle in the observed image. The particle size is determined as the particle size (maximum length) of each particle. That is, the particle size is the primary particle size.

[0172] (3) Perform the above operations (1) and (2) five times on the same optical sheet as the test object, and measure the particle size of a total of 50 particles. Take the average value of the total 50 particle size measurements as the average particle size (nm).

[0173] The “average thickness” of functional layer 40 is a value determined by the following (4) to (6).

[0174] (4) Use a transmission electron microscope (TEM) to photograph the cross section of the optical sheet containing the functional layer.

[0175] (5) Measure the thickness of the functional layer at the center position along the surface of the optical sheet in the captured image, and the thickness of the functional layer at a position offset 100 nm from the center position to both sides along the surface of the optical sheet. The thickness is the length (nm) of the functional layer along a direction orthogonal to the surface of the optical sheet.

[0176] (6) Perform the above operations (4) and (5) five times on the same optical sheet as the measurement object, and measure the thickness of the functional layer at a total of 15 locations. The average value of the total 15 thickness measurements is taken as the average thickness (nm) of the functional layer.

[0177] <<Visual Reflectivity>>

[0178] The optical sheet 10 can have a reflection suppression function to suppress the reflection of light incident on the first surface 11. The apparent reflectance Y value of the first surface 11, measured at an incident angle of 5°, can be less than 1.7%, less than 1.5%, less than 1.4%, less than 1.0%, less than 0.8%, less than 0.7%, less than 0.6%, or less than 0.5%.

[0179] There is no specific lower limit for visual reflectance. The visual reflectance Y value of the first surface 11, measured at an incident angle of 5°, can be above 0% or greater than 0%.

[0180] The apparent reflectance Y value of the first surface 11, measured at an incident angle of 5°, can be greater than 0% and less than 1.7%, greater than 0% and less than 1.5%, greater than 0% and less than 1.4%, greater than 0% and less than 1.0%, greater than 0% and less than 0.8%, greater than 0% and less than 0.7%, greater than 0% and less than 0.6%, or greater than 0% and less than 0.5%. The apparent reflectance Y value of the first surface 11, measured at an incident angle of 5°, can be greater than 0% and less than 1.7%, greater than 0% and less than 1.5%, greater than 0% and less than 1.4%, greater than 0% and less than 1.0%, greater than 0% and less than 0.8%, greater than 0% and less than 0.7%, greater than 0% and less than 0.6%, or greater than 0% and less than 0.5%.

[0181] The visual reflectance Y value is the visual reflectance Y value of the CIE 1931 standard color system. The visual reflectance Y value (%) is measured using a spectrophotometer as follows.

[0182] A sample is cut from the optical sheet 10, which is to be evaluated. The sample is visually confirmed to be free of dust, scratches, or other abnormalities. A black plate is attached to the sample surface, which is the second side of the optical sheet, via an optically transparent adhesive sheet. The optically transparent adhesive sheet is "PANACLEAN PD-S1" manufactured by PANAC Corporation. The black plate is "COMOGLASS DFA2CG502K (Black) series" manufactured by Kuraray Corporation. The thickness of the black plate is 2 mm. The total light transmittance of the black plate is less than 1%. Through the above operations, an evaluation sample A, comprising the optical sheet, the optically transparent adhesive sheet, and the black plate, is prepared.

[0183] The surface of evaluation sample A, which is composed of the first surface of the optical sheet, is illuminated with light at an incident angle of 5°. The reflectance (apparent reflectance Y value) of the evaluation sample A is measured based on the orthogonal reflected light. Using an auxiliary light source C and a 2-degree field of view, the apparent reflectance Y (%) is calculated based on the orthogonal reflectance measured at 0.5 nm intervals in the range from 300 nm to 780 nm. Before measuring the apparent reflectance Y value of the optical sheet 10, the auxiliary light source C is illuminated for 15 minutes to allow its output to stabilize. The test environment for measuring the apparent reflectance is set to a temperature of 23℃ ± 2℃ and a relative humidity of 50% ± 5%. The sample is placed in the test environment for 16 hours before the start of the test.

[0184] Other measurement conditions for measuring visual reflectance shall be in accordance with JIS Z 8722:2009.

[0185] The perceived reflectance is the arithmetic mean of five measurements. These five measurements were taken at five locations on the optical sheet being evaluated. The five locations are separated by more than 10 mm from each other.

[0186] <<Total Light Transmittance>>

[0187] The total light transmittance of the optical sheet 10 can be above 50%, above 70%, above 80%, or above 90%. There is no specific upper limit to the total light transmittance of the optical sheet 10. The total light transmittance of the optical sheet 10 can be below 100%, or even less than 100%.

[0188] The total light transmittance of the optical sheet 10 can be above 50% and below 100%, above 70% and below 100%, above 80% and below 100%, or above 90% and below 100%. Alternatively, the total light transmittance of the optical sheet 10 can be above 50% and below 100%, above 70% and below 100%, above 80% and below 100%, or above 90% and below 100%.

[0189] Total light transmittance (%) was determined using a light source simulating the spectrum of the D65 standard light (also known as the "D65 light source"). Before measuring the total light transmittance of the optical sheet 10, the D65 light source was illuminated for 15 minutes to stabilize its output. The angle of incidence on the sample was set to 0° during the total light transmittance measurement. The incident surface for measuring total light transmittance was the second surface 12 of the optical sheet 10. The test environment for measuring total light transmittance was set to a temperature of 23℃ ± 2℃ and a relative humidity of 50% ± 5%. The sample was placed in the test environment for 16 hours before the start of the test. Other measurement conditions for total light transmittance were in accordance with JIS K7361-1:1997.

[0190] Total light transmittance was set as the arithmetic mean of five measurements. These five measurements were taken at five locations on the optical sheet being evaluated. The five measurement locations were situated at least 10 mm apart.

[0191] <<Transmitted Haze>>

[0192] The transmission haze of the optical sheet 10 can be below 1.0%, below 0.5%, or below 0.2%. There is no specific lower limit for the transmission haze of the optical sheet 10. The transmission haze of the optical sheet 10 can be above 0% or greater than 0%.

[0193] The transmission haze of the optical sheet 10 can be above 0% and below 1.0%, above 0% and below 0.5%, or above 0% and below 0.2%. The transmission haze of the optical sheet 10 can be above 0% and below 1.0%, above 0% and below 0.5%, or above 0% and below 0.2%.

[0194] The transmitted haze (%) was measured using a D65 light source. Before measuring the transmitted haze of the optical sheet 10, the D65 light source was lit for 15 minutes to stabilize its output. The incident angle of the sample was set to 0° during the transmitted haze measurement. The incident surface was the second surface 12 of the optical sheet 10. The test environment for measuring the transmitted haze was set to a temperature of 23℃±2℃ and a relative humidity of 50%±5%. The sample was placed in the test environment for 16 hours before the test. Other measurement conditions for the transmitted haze were in accordance with JIS K7136:2000.

[0195] Transmitted haze is the arithmetic mean of five measurements. These five measurements were taken at five locations on the optical sheet being evaluated. The five locations are separated by more than 10 mm from each other.

[0196] Reference Figure 1 The optical sheet 10 shown is further illustrated with a detailed description of the layers comprised of the optical sheet 10. For example... Figure 1 As shown, the optical sheet 10 may further include a resin layer 30. Figure 1 In the example shown, substrate 20, resin layer 30, and functional layer 40 are stacked on a third direction D3. The illustrated functional layer 40 contains hollow silica particles 43 as metal oxide particles 42. In the following description, functional layer 40 is described as a low-reflection layer or reflection-suppressing layer with the function of suppressing reflection. This functional layer 40 has a lower refractive index than the adjacent layer (resin layer 30 in the illustrated example).

[0197] The third direction D3 is the lamination direction. The substrate 20, resin layer 30, and functional layer 40 extend along the first direction D1 and the second direction D2, which are orthogonal to the third direction D3. In the illustrated example, the first direction D1 and the second direction D2 are orthogonal to each other. Figure 1 In the optical sheet 10 shown, the first surface 11 is composed of a functional layer 40. The second surface 12 is composed of a substrate 20.

[0198] The optical element 10 sometimes also has an antistatic layer and an antifouling layer, which are supported by the functional layer 40 to form the first surface 11. These antistatic and antifouling layers are very thin. Otherwise, the functional layer 40 would not be able to effectively perform its reflection suppression function. Therefore, in the example where the first surface 11 is formed by an antistatic layer and an antifouling layer, the scratch resistance of the first surface 11 is also affected by the functional layer 40. That is, according to the aforementioned functional layer 40, the scratch resistance of the first surface 11 can be significantly improved.

[0199] <<Substrate>>

[0200] The substrate 20 supports the resin layer 30 and the functional layer 40. The substrate 20 may be transparent. Transparency means that the total light transmittance is 50% or more, 70% or more, 80% or more, or 90% or more, according to JIS K 7361-1:1997.

[0201] The material of the substrate 20 is not particularly limited; it can be resin or glass. Resin is preferred due to its lightweight and ease of manufacture.

[0202] The resin used for the substrate 20 can be a polyolefin resin such as polyethylene or polypropylene. The resin used for the substrate 20 can be a vinyl resin such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, or ethylene-vinyl alcohol copolymer. The resin used for the substrate 20 can be a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate. The resin used for the substrate 20 can be an acrylic resin such as poly(methyl methacrylate) or poly(ethyl methacrylate). The resin used for the substrate 20 can be a styrene resin such as polystyrene, a polyamide resin such as nylon 6 or nylon 66, or a cellulose resin such as triacetyl cellulose. Examples of resins used in the substrate 20 include polycarbonate resins, polyimide resins, and cyclic olefin resins obtained from cyclic olefins such as norbornene or dicyclopentadiene. The resin layer 30 may contain only one of the above-mentioned resins or may contain two or more of the above-mentioned resins.

[0203] The thickness of the resin substrate 20 is not particularly limited. From a processability point of view, the thickness of the resin substrate 20 can be 10 μm or more, 20 μm or more, or 50 μm or more. The thickness of the resin substrate 20 can be 500 μm or less, 400 μm or less, or 300 μm or less. The thickness of the resin substrate 20 can be 10 μm or more and 500 μm or less, 20 μm or more and 500 μm or less, or 50 μm or more and 500 μm or less. The thickness of the resin substrate 20 can be 10 μm or more and 400 μm or less, 20 μm or more and 400 μm or less, or 50 μm or more and 400 μm or less. The thickness of the resin substrate 20 can be 10 μm or more and 300 μm or less, 20 μm or more and 300 μm or less, or 50 μm or more and 300 μm or less. The thickness of the resin-based substrate 20 can be 500 μm or more.

[0204] When the optical sheet 10 is used in a foldable application, the substrate 20 can also be flexible. In this example, the thickness of the resin substrate 20 can be 10 μm or more and 40 μm or less. When the optical sheet 10 is used in a laminate with glass, from the viewpoint of preventing glass scattering, the thickness of the resin substrate 20 can be 40 μm or more and 100 μm or less.

[0205] The substrate 20 may contain a single layer or multiple layers. The substrate 20 may include an adhesive layer or other base coating.

[0206] <<Functional Layer>>

[0207] Functional layer 40 includes binder component 41 and metal oxide particles 42. Metal oxide particles 42 may include hollow silica particles 43. Metal oxide particles 42 may also include particles other than hollow silica particles 43. Functional layer 40 reduces its refractive index by including hollow silica particles 43. Functional layer 40 may have a lower refractive index than binder component 41. The refractive index of functional layer 40 may be lower than the refractive index of substrate 20. The refractive index of functional layer 40 may be lower than the refractive index of layers adjacent to functional layer 40.

[0208] The functional layer 40, due to its refractive index and thickness, is able to suppress the reflection of incident light. The anti-reflection function of the functional layer 40 is based on the interference of light reflected from the surfaces on both sides of the functional layer 40. From the viewpoint of making this reflection suppression function effective, the refractive index of the functional layer 40 can be the magnitude between the refractive indices of the two regions adjacent to the functional layer 40 on both sides. The thickness (nm) of the functional layer 40 can be approximately 1 / 4 of the wavelength λ (nm) of the light to be suppressed.

[0209] The thickness of the functional layer can be 60nm or more and below 120nm, or 70nm or more and below 120nm, or 80nm or more and below 120nm. The thickness of the functional layer can be 60nm or more and below 110nm, or 70nm or more and below 110nm, or 80nm or more and below 110nm. The thickness of the functional layer can be 60nm or more and below 100nm, or 70nm or more and below 100nm, or 80nm or more and below 100nm.

[0210] From the perspective of reflection suppression, the refractive index and average thickness of the functional layer can be set as follows: The refractive index of the functional layer can be 1.10 or higher, 1.20 or higher, 1.26 or higher, 1.28 or higher, or 1.30 or higher. The refractive index of the functional layer can be below 1.48, below 1.45, below 1.40, below 1.38, or below 1.35.

[0211] The refractive index of the functional layer can be 1.10 or higher and 1.48 or lower, 1.20 or higher and 1.48 or lower, 1.26 or higher and 1.48 or lower, 1.28 or higher and 1.48 or lower, or 1.30 or higher and 1.48 or lower. The refractive index of the functional layer can also be 1.10 or higher and 1.45 or lower, 1.20 or higher and 1.45 or lower, 1.26 or higher and 1.45 or lower, 1.28 or higher and 1.45 or lower, or 1.30 or higher and 1.45 or lower. (This last sentence is repeated three times in the original text.) The refractive index of the functional layer can be above 1.10 and below 1.38, above 1.20 and below 1.38, above 1.26 and below 1.38, above 1.28 and below 1.38, or above 1.30 and below 1.38. The refractive index of the functional layer can also be above 1.10 and below 1.35, above 1.20 and below 1.35, above 1.26 and below 1.35, above 1.28 and below 1.35, or above 1.30 and below 1.35.

[0212] The refractive index used for the constituent elements of the optical sheet is the refractive index relative to a wavelength of 589.3 nm.

[0213] The thickness of the functional layer can be above 80nm, above 85nm, or above 90nm. The thickness of the functional layer can be below 150nm, below 110nm, or below 105nm. The thickness of the functional layer can be between 80nm and 150nm, between 85nm and 150nm, or between 90nm and 150nm. The thickness of the functional layer can be between 80nm and 110nm, between 85nm and 110nm, or between 90nm and 110nm. The thickness of the functional layer can be between 80nm and 105nm, between 85nm and 105nm, or between 90nm and 105nm.

[0214] <Adhesive components>

[0215] The binder component 42 is an element that retains the metal oxide particles 42. The binder component 42 can also function as a binder for forming a coating film. By retaining the particles contained in the functional layer 40 through the binder component 42, the functional layer 40 can maintain its film morphology. The binder component 42 may contain a resin. The resin contained in the binder component 42 can be a natural resin or a synthetic resin. The binder component 42 can encapsulate the particles contained in the functional layer 40. The binder component 42 can completely surround each particle contained in the functional layer 40, or it can leave at least a portion of the particles partially exposed.

[0216] The adhesive component 41 may contain a cured product of a curable resin composition. The curable resin composition may contain one or more of a thermosetting resin composition and an ionizing radiation curable resin composition. The cured product of the curable resin composition can impart high strength and high hardness to the functional layer 40, improving the scratch resistance of the first surface 11. From the viewpoint of improving scratch resistance, ionizing radiation curable resin compositions are particularly useful.

[0217] The thermosetting resin composition comprises a thermosetting resin. The thermosetting resin composition is cured by heating. Examples of thermosetting resins include acrylic resins, polyurethane resins, phenolic resins, urea-melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. The thermosetting resin composition may contain a curing agent.

[0218] The ionizing radiation-curable resin composition comprises an ionizing radiation-curable compound. The ionizing radiation-curable compound comprises an ionizing radiation-curable functional group. Examples of ionizing radiation-curable functional groups include olefinic unsaturated groups such as (meth)acryloyl, vinyl, and allyl, as well as epoxy and oxetyl groups. The ionizing radiation-curable compound may contain two or more ionizing radiation-curable functional groups. The ionizing radiation-curable compound may be a compound having olefinic unsaturated groups. The ionizing radiation-curable compound may be a (meth)acrylate compound having a (meth)acryloyl group.

[0219] The ionizing radiation-curable compound can be a siloxane-based compound containing siloxane bonds. That is, a composition containing a UV-curable siloxane-based compound can be used. By forming a functional layer using a composition containing a UV-curable siloxane-based compound, the average area of ​​the Voronoi region can be increased.

[0220] Compared to pentaerythritol triacrylate, which is frequently used in functional layers, compositions containing UV-curable siloxane compounds are less likely to penetrate into the underlying layer. Therefore, compositions containing UV-curable siloxane compounds are more susceptible to coating metal oxide particles also present in the coating solution used for functional layers. That is, metal oxide particles are easily encapsulated by the resin in the functional layer. As a result, in functional layers fabricated using compositions containing UV-curable siloxane compounds, the average area of ​​the Voronoi region tends to increase, achieving an average Voronoi region area of ​​2500 nm. 2 above.

[0221] The functional layer made using a composition containing a UV-curable siloxane compound comprises a cured product of the composition containing a UV-curable siloxane compound. The adhesive component of the functional layer made using a composition containing a UV-curable siloxane compound comprises a cured product of the composition containing a UV-curable siloxane compound. The functional layer made using a composition containing a UV-curable siloxane compound comprises a siloxane compound. The adhesive component of the functional layer made using a composition containing a UV-curable siloxane compound comprises a siloxane compound. Therefore, in the functional layer containing the siloxane compound, the average area of ​​the Voronoi region is easily increased, enabling the average area of ​​the Voronoi region to reach 2500 nm. 2 above.

[0222] The presence of siloxane compounds is confirmed by detecting organic Si components using X-ray photoelectron spectroscopy (XPS). If organic Si is detected by XPS, the compound is considered to contain siloxane compounds. If organic Si is not detected by XPS, the compound is considered to be non-siloxane-based.

[0223] In X-ray photoelectron spectroscopy (XPS), an XPS apparatus is used to confirm whether the functional layer contains organic Si components. An example of an XPS apparatus is the AXIS-Nova XPS analyzer manufactured by Kratos Analtyical.

[0224] In the quantitative analysis of elements present in functional layers based on X-ray photoelectron spectroscopy, the X-ray photoelectron spectra of the C1s, O1s, Si2p, and F1s orbitals on the surface of the functional layer of the sample to be measured are determined under the conditions described below. The following conditions are selected for the measurement.

[0225] (Measurement conditions)

[0226] Measurement method: Wide-Narrow

[0227] X-ray source: Monochromatic AlKα

[0228] X-ray output: 150W

[0229] Transmitting current: 10mA

[0230] Accelerating voltage: 15kV

[0231] Charge neutralization mechanism: ON

[0232] Measurement area: 300μm × 700μm

[0233] Pass Energy: Survey:160eV、Narrow:40eV

[0234] Photoelectron acquisition angle: 90°

[0235] Auto-Z (Autofocus): ON

[0236] Peak shift correction: Correction was performed with the peak value of CC in the C1s peak set at 285.0 eV.

[0237] Narrow peak waveform separation: This is implemented using the analysis software provided with the device and GL functions.

[0238] Etching ions: Ar monoatomic ions

[0239] Examples of siloxane compounds include (poly)dimethylsiloxane, (poly)diethylsiloxane, (poly)diphenylsiloxane, (poly)methylphenylsiloxane, alkyl-modified (poly)dimethylsiloxane, azo-containing (poly)dimethylsiloxane, dimethyl organosilicon, phenylmethyl organosilicon, alkyl·aralkyl-modified organosilicon, fluorinated organosilicon, polyether-modified organosilicon, fatty acid ester-modified organosilicon, methylhydro organosilicon, silanol-containing organosilicon, alkoxy-containing organosilicon, phenol-containing organosilicon, methacrylic acid-modified organosilicon, acrylic acid-modified organosilicon, amino-modified organosilicon, carboxylic acid-modified organosilicon, methanol-modified organosilicon, epoxy-modified organosilicon, mercapto-modified organosilicon, fluorinated organosilicon, and polyether-modified organosilicon.

[0240] The thickness of the functional layer containing siloxane compounds can be above 60 nm, above 70 nm, or above 80 nm. The thickness of the functional layer containing siloxane compounds can be below 120 nm, below 110 nm, or below 100 nm.

[0241] The thickness of the functional layer containing siloxane compounds can be 60 nm or more and 120 nm or less, 70 nm or more and 120 nm or less, or 80 nm or more and 120 nm or less. The thickness of the functional layer containing siloxane compounds can be 60 nm or more and 110 nm or less, 70 nm or more and 110 nm or less, or 80 nm or more and 110 nm or less. The thickness of the functional layer containing siloxane compounds can be 60 nm or more and 100 nm or less, 70 nm or more and 100 nm or less, or 80 nm or more and 100 nm or less.

[0242] When a functional layer of this thickness contains a siloxane-based compound, the average area of ​​the Voronoi region can easily be increased, making the average area of ​​the Voronoi region 2500 nm. 2 above.

[0243] The functional layer containing siloxane compounds suppresses the formation of the permeation layer, thus enabling the precise achievement of a specified thickness. Furthermore, the dispersion of hollow silica particles is improved in the functional layer containing siloxane compounds. Therefore, by setting the thickness of the functional layer containing siloxane compounds within the aforementioned numerical range, for example, 60 nm or more and 120 nm or less, the resulting functional layer has the desired thickness and becomes homogeneous. That is, it is possible to impart high-precision reflection suppression or low-reflection functionality to the functional layer. Additionally, the average area of ​​the aforementioned Voronoi region can be easily increased, enabling the average area of ​​the Voronoi region to reach 2500 nm. 2 The above results in improved scratch resistance on the first surface.

[0244] (Meth)acrylate compounds containing four or more olefinic unsaturated groups are called "polyfunctional (meth)acrylate compounds". (Meth)acrylate compounds having two to three olefinic unsaturated groups are called "low-functional (meth)acrylate compounds".

[0245] (Meth)acrylate compounds can be monomers or oligomers. Ionizing radiation-curable compounds containing low-functionality (meth)acrylate compounds can suppress uneven shrinkage during curing, thus smoothing the surface of the functional layer 40.

[0246] The proportion of low-functional (meth)acrylate compounds in the ionizing radiation curable compound can be 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass. From the viewpoint of smoothing the surface irregularity of the functional layer 40 by suppressing uneven shrinkage during curing, the low-functional (meth)acrylate compound can be a (meth)acrylate compound containing two olefin unsaturated groups. When the ionizing radiation curable compound contains a large amount of polyfunctional (meth)acrylate compounds, as described later, the surface of the functional layer can be smoothed by appropriately adjusting the type of solvent and drying conditions.

[0247] Examples of difunctional (meth)acrylate compounds include dimethacrylate isocyanurate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polybutylene glycol dimethacrylate, and other polyalkylene glycol dimethacrylates, bisphenol A tetraethoxydimethacrylate, bisphenol A tetrapropoxydimethacrylate, and 1,6-hexanediol dimethacrylate. Examples of trifunctional (meth)acrylate compounds include trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, and isocyanuric acid-modified trimethacrylate. Examples of polyfunctional (meth)acrylate compounds with four or more functions include pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, and dipentaerythritol tetramethacrylate. (Meth)acrylate compounds can be modified as described below.

[0248] Examples of (meth)acrylate oligomers include urethane (meth)acrylates, epoxy (meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates, and other acrylate polymers. Uramate (meth)acrylates are obtained, for example, by reacting polyols and organic diisocyanates with hydroxyl (meth)acrylates. Epoxy (meth)acrylates can also be obtained by reacting trifunctional or higher aromatic epoxy resins, alicyclic epoxy resins, or aliphatic epoxy resins with (meth)acrylate. Epoxy (meth)acrylates can also be obtained by reacting difunctional or higher aromatic epoxy resins, alicyclic epoxy resins, or aliphatic epoxy resins with polybasic acids and (meth)acrylate. Epoxy (meth)acrylates can also be obtained by reacting difunctional or higher aromatic epoxy resins, alicyclic epoxy resins, or aliphatic epoxy resins with phenols and (meth)acrylate.

[0249] From the perspective of suppressing uneven shrinkage caused by crosslinking, (meth)acrylate compounds can modify a portion of their molecular backbone. For example, (meth)acrylate compounds can be modified using ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl groups, cyclic alkyl groups, aromatic groups, bisphenols, etc. These (meth)acrylate compounds can also be modified using epoxides such as ethylene oxide and propylene oxide. The proportion of epoxide-modified (meth)acrylate compounds in ionizing radiation-curable compounds can be 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass. Epoxide-modified (meth)acrylate compounds can be low-functionality (meth)acrylate compounds or (meth)acrylate compounds having two olefinic unsaturated bond groups.

[0250] Examples of methacrylate compounds modified with alkylene oxide and having two olefinically unsaturated groups include bisphenol F alkylene oxide-modified di(meth)acrylate, bisphenol A alkylene oxide-modified di(meth)acrylate, isocyanuric acid alkylene oxide-modified di(meth)acrylate, and polyalkylene glycol di(meth)acrylate. The average repeating unit of the alkylene glycol in the polyalkylene glycol di(meth)acrylate can be 3 to 5. The alkylene glycol in the polyalkylene glycol di(meth)acrylate can be ethylene glycol and / or polyethylene glycol. Examples of methacrylate compounds modified with alkylene oxide and having three olefinically unsaturated groups include trimethylolpropane alkylene oxide-modified tri(meth)acrylate and isocyanuric acid alkylene oxide-modified tri(meth)acrylate.

[0251] One type of ionizing radiation curing compound can be used alone, or two or more ionizing radiation curing compounds can be used in combination.

[0252] When the ionizing radiation curable compound is an ultraviolet curable compound, the curable resin composition forming the adhesive component 41 may also include additives such as photopolymerization initiators and photopolymerization accelerators. Examples of photopolymerization initiators include one or more selected from acetophenone, benzophenone, α-hydroxyalkyl phenyl ketone, mischlerone, benzoin, benzoyl benzoate, benzoylbenzoate, α-acyl oxime ester, α-aminoalkyl phenyl ketone, and thioxanthone derivatives. Photopolymerization accelerators can reduce polymerization hindrance caused by air during curing and accelerate the curing speed. Examples of photopolymerization accelerators include one or more selected from isoamyl p-dimethylaminobenzoate and ethyl p-dimethylaminobenzoate.

[0253] <Metal oxide particles and other particles>

[0254] The metal oxide particles 42 contained in the functional layer 40 may include hollow silica particles 43. The metal oxide particles 42 may also include particles other than the hollow silica particles 43. For example... Figure 1 As shown, the functional layer 40 may contain solid silicon dioxide particles 44 as metal oxide particles 42. The functional layer 40 may also contain inorganic particles or organic particles other than metal oxide particles 42. The inorganic particles may be magnesium fluoride particles.

[0255] Hollow silica particles 43 have an outer shell layer made of silica. Within the hollow silica particles 43, the interior of the particles surrounded by the outer shell layer is formed as voids. These voids may contain air. The hollow silica particles 43 have a refractive index lower than that of silica due to the inclusion of internal voids. The refractive index of the hollow silica particles 43 decreases as the volume of the internal voids increases. The hollow silica particles 43 reduce the overall refractive index of the functional layer 40. By using hollow silica particles 43 with a larger particle size that increase the ratio of internal space, the refractive index of the functional layer 40 can be further reduced.

[0256] Hollow silica particles 43 can be uniformly dispersed within the functional layer 40. By uniformly dispersing the hollow silica particles 43 within the functional layer 40, the protrusion of the hollow silica particles 43 from the first surface 11 is suppressed, and the first surface 11 is smoothed. This improves the slip properties of the first surface 11 and enhances its scratch resistance. Furthermore, by uniformly dispersing the hollow silica particles 43 within the functional layer 40, the standard deviation of the area of ​​the Voronoi region can be reduced.

[0257] From the viewpoint of uniformly dispersing the hollow silica particles 43 within the functional layer 40, the following adjustments are effective: The particle size deviation of the hollow silica particles 43 can be reduced. The average particle size of the hollow silica particles 43 relative to the average film thickness of the binder component 41 can be adjusted as described above. The affinity between the hollow silica particles 43 and the binder component 41 can be adjusted. The ratio of the content of the hollow silica particles 43 to that of other particles contained in the functional layer 40, and the ratio of their average particle sizes, can be adjusted. The affinity between the hollow silica particles 43 and other particles contained in the functional layer 40 can be adjusted.

[0258] From the viewpoint of uniformly dispersing hollow silica particles within the functional layer, the binder component of the functional layer can contain a siloxane-based compound. Based on the functional layer containing both hollow silica particles and a siloxane-based compound, it is possible to uniformly disperse the hollow silica particles within the functional layer. Furthermore, a desired thickness can be imparted to the functional layer. Therefore, it is possible to impart highly precise reflection suppression or low-reflection functionality to the functional layer.

[0259] Solid silica particles 44 are non-hollow silica particles. Solid silica particles 44 are particles without internal cavities. Solid silica particles 44 can be solid silica particles.

[0260] The average particle size of the solid silica particles 44 is typically smaller than that of the hollow silica particles 43. Therefore, the solid silica particles 44 can penetrate between adjacent hollow silica particles 43 within the functional layer 40. By including the solid silica particles 44 in the functional layer 40, the strength and hardness of the functional layer 40 are enhanced, further improving the scratch resistance of the first surface 11. The refractive index of the solid silica particles 44 is lower than that of most metal oxide particles 42. Therefore, by including the solid silica particles 44 in the functional layer 40, the refractive index of the functional layer 40 can be reduced. By including the solid silica particles 44 in the functional layer 40, the reflection suppression function of the functional layer 40 can be enhanced.

[0261] Solid silica particles 44 can be uniformly dispersed together with hollow silica particles 43 within the functional layer 40. By uniformly dispersing the solid silica particles 44 and hollow silica particles 43 within the functional layer 40, the protrusion of metal oxide particles 42 from the first surface 11 is suppressed, and the first surface 11 is smoothed. This improves the slip properties of the first surface 11 and enhances its scratch resistance. The uniform dispersion of metal oxide particles 42 within the functional layer 40 reduces the standard deviation of the area of ​​the Voronoi region. By adjusting the ratio of the content of solid silica particles 44 to other particles and the ratio of their average particle size, the solid silica particles 44 and hollow silica particles 43 can be uniformly dispersed together within the functional layer 40. By adjusting the affinity of solid silica particles 44 to other particles, the solid silica particles 44 and hollow silica particles 43 can be uniformly dispersed together within the functional layer 40.

[0262] The functional layer 40 may also include metal oxide particles 42 other than silicon dioxide particles. The metal oxide particles 42, other than silicon dioxide particles, can enhance the strength and hardness of the functional layer 40 and improve the scratch resistance of the first surface 11. Examples of metal oxide particles 42 include elemental oxides or mixtures of oxides from aluminum oxide, titanium, tantalum, zirconium, chromium, niobium, cerium, hafnium, and yttrium. The metal oxide particles 42, other than silicon dioxide, can be hollow particles with internal spaces or solid particles without internal spaces.

[0263] By including metal oxide particles 42 other than silica particles in addition to hollow silica particles 43, the scratch resistance of the first surface 11 can be further improved in the functional layer 40. The detailed reasons for the improved scratch resistance are not yet clear, but it is speculated that the following factors contribute to the improvement of scratch resistance. However, this disclosure is not limited to the following assumptions.

[0264] In the adhesive component 41, in addition to hollow silica particles 43, metal oxide particles 42 other than silica particles are also dispersed. The average particle size of the hollow silica particles 43 is generally larger than the average particle size of the metal oxide particles 42 other than silica particles. Therefore, the metal oxide particles 42 other than silica particles can be interposed between the hollow silica particles 43 within the adhesive component 41. As a result, the hydroxyl groups of the metal oxide particles 42 other than silica particles can form hydrogen bonds with the hydroxyl groups of the hollow silica particles 43. The hydroxyl groups of the metal oxide particles 42 other than silica particles can form hydrogen bonds with the hydroxyl groups of the adhesive component. That is, it is presumed that cross-linking in the functional layer 40 is achieved by dispersing metal oxide particles 42 other than silica particles in the adhesive component 41 in addition to the hollow silica particles 43. The metal oxide particles 42 other than silica particles can link the hollow silica particles 43 to each other. The metal oxide particles 42 other than silica particles can link the hollow silica particles 43 to the adhesive component 41. Based on the above, it is speculated that by including both metal oxide particles 42 (other than silicon dioxide particles) and hollow silicon dioxide particles 43 in the functional layer 40, the strength and hardness of the functional layer 40 are enhanced, and the scratch resistance of the first surface 11 formed by the functional layer 40 is enhanced.

[0265] The functional layer 40 may contain alumina particles as metal oxide particles 42 other than silica particles. Alumina particles have a low refractive index among metal oxides. Alumina is aluminum oxide represented by Al₂O₃, and is known to exist in α-type, γ-type, σ-type, and mixtures thereof. The alumina particles may also be surface-modified alumina particles. Examples of modified alumina particles include (meth)acrylic acid-modified alumina particles and organosilicon-modified alumina particles.

[0266] Alumina, as an oxide of aluminum, can bond with the hollow silica particles 43 and the binder component 41 within the functional layer 40. Therefore, cross-linking occurs within the functional layer 40, further strengthening it. This enhances the strength and hardness of the functional layer 40, further improving the scratch resistance of the first surface 11. The average particle size of the alumina particles is typically smaller than the average particle size of the hollow silica particles 43. Therefore, the alumina particles can penetrate between the hollow silica particles 43 within the functional layer 40. This effectively improves the scratch resistance of the first surface 11.

[0267] Furthermore, alumina particles can be distributed along the surface direction near the surface of functional layer 40. Therefore, the strength and hardness near the surface of functional layer 40 are effectively enhanced. This results in significantly improved resistance to abrasion from more demanding rubbers.

[0268] The presence of metal oxide particles 42, excluding silica particles, increases the total amount of metal oxide particles 42 within the functional layer 40 while suppressing the protrusion of metal oxide particles 42 from the first surface 11. This improves the sliding properties of the first surface 11 and enhances its scratch resistance. Furthermore, the uniform dispersion of metal oxide particles 42 within the functional layer 40 reduces the standard deviation of the area of ​​the Voronoi region.

[0269] When the average particle size of the hollow silica particles 43 differs significantly from the average particle size of the metal oxide particles 42 other than silica particles, agglomeration of the metal oxide particles 42 other than silica particles occurs. Adjacent hollow silica particles 43 are more firmly bonded by the agglomerated metal oxide particles 42 other than silica particles. Through the agglomerated metal oxide particles 42 other than silica particles, the hollow silica particles 43 and the binder component 41 are more firmly bonded. As a result, the strength and hardness of the functional layer 40 are enhanced, further improving the scratch resistance of the first surface 11.

[0270] Metal oxide particles 42, other than silica particles, can also be bonded to solid silica particles 44. These metal oxide particles 42 also form hydrogen bonds with the solid silica particles 44, promoting cross-linking within the functional layer 40. Therefore, the functional layer 40 can comprise solid silica particles 44 and metal oxide particles other than silica particles as metal oxide particles 42.

[0271] The shapes of the hollow silica particles 43, solid silica particles 44, and alumina dispersed within the functional layer 40 are not particularly limited. The shapes of the particles contained in the functional layer 40 can be approximately spherical, rod-shaped, plate-shaped, fibrous, or irregular, such as perfect spheres, ellipsoids of revolution, or polyhedral shapes that approximate spheres. By making the shapes of the particles contained in the functional layer 40 perfect spheres, ellipsoids of revolution, or approximately spherical, the sliding properties of the first surface 11 are improved, and the scratch resistance of the first surface 11 is enhanced.

[0272] The surface of the particles contained in functional layer 40 can be coated with a silane coupling agent. The silane coupling agent may contain (meth)acryloyl groups or epoxy groups. By subjecting the particles to surface treatment with a silane coupling agent, the affinity between the particles and the binder components is improved, and the particles are less prone to aggregation. As a result, the particles are more uniformly dispersed within the binder components.

[0273] Examples of silane coupling agents include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3- Triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, tris(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, 1,6-bis(trimethoxysilyl)hexane, trifluoropropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane, etc. In particular, it can be one or more selected from 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane and 3-methacryloxypropyltriethoxysilane.

[0274] The average particle size of the hollow silica particles 43 can be larger than the average particle size of the solid silica particles 44 and the metal oxide particles 42 other than silica particles. The average particle size of the hollow silica particles 43 can be greater than 50 nm or greater than 65 nm. The average particle size of the hollow silica particles 43 can be less than 100 nm or less than 80 nm.

[0275] The average particle size of the solid silica particles 44 is not particularly limited. The average particle size of the solid silica particles 44 can be 5 nm or more, or 10 nm or more. The average particle size of the solid silica particles 44 can be less than 20 nm, or less than 15 nm. In addition to or instead of solid silica particles 44 with such an average particle size, the functional layer 40 may contain solid silica particles 44 with an average particle size of 60 μm or more and less than 100 μm.

[0276] The average particle size of the metal oxide particles 42 (excluding silicon dioxide) and the average particle size of the alumina particles can be greater than 5 nm or greater than 10 nm. The average particle size of the metal oxide particles 42 (excluding silicon dioxide) and the average particle size of the alumina particles can be less than 20 nm or less than 15 nm.

[0277] If the content of hollow silica particles 43 increases, the refractive index of the functional layer 40 decreases, and the functional layer 40 can exert excellent reflection suppression function. That is, from the viewpoint of the reflection suppression function of the functional layer 40, a lower limit can be set for the content of hollow silica particles 43. By setting a lower limit for the content of particles other than hollow silica particles 43, the smoothness, strength, and hardness of the functional layer 40 can be ensured. By setting a lower limit for the content of binder component 41, the particles can be stably held by the binder component 41. Thus, particle shedding can be suppressed, ensuring excellent scratch resistance. By setting an upper limit for the content of binder component 41, the refractive index of the functional layer 40 decreases, and the functional layer 40 can exert excellent reflection suppression function. By setting an upper limit for the content of each particle, significant aggregation of the particles can be suppressed.

[0278] The content of hollow silica particles relative to 100 parts by weight of the adhesive component can be more than 100 parts by weight, more than 150 parts by weight, or more than 175 parts by weight. The content of hollow silica particles relative to 100 parts by weight of the adhesive component can be less than 400 parts by weight, less than 300 parts by weight, or less than 250 parts by weight.

[0279] The content of solid silica particles relative to 100 parts by weight of the binder can be 10 parts by weight or more, 50 parts by weight or more, 70 parts by weight or more, or 100 parts by weight or more. The content of solid silica particles relative to 100 parts by weight of the binder can be less than 200 parts by weight, less than 150 parts by weight, or less than 100 parts by weight.

[0280] <How to create Functional Layer 40>

[0281] The functional layer 40 can be made using a coating liquid containing a curable resin composition and particles. The functional layer 40 can be obtained by curing the coating film of the coating liquid. In this example, the coating liquid used to make the functional layer 40 may contain additives such as antistatic agents, antioxidants, surfactants, dispersants, and ultraviolet absorbers.

[0282] The coating liquid for the functional layer may contain a silicone-based leveling agent (silicone compound) as an additive. By including a silicone-based leveling agent in the coating liquid for the functional layer, the protrusion of hollow silica particles 43 from the first surface 11 is suppressed, and the first surface 11 is smoothed. As a result, the sliding properties of the first surface 11 are improved, and the scratch resistance of the first surface 11 is enhanced. According to the silicone-based leveling agent, the surface of the functional layer 40 can be endowed with excellent sliding properties and excellent anti-fouling properties (fingerprint wiping resistance, large contact angle with pure water and hexadecane).

[0283] By using silicone-based leveling agents instead of fluorine-based leveling agents, the formation of PFAS as impurities can be suppressed. PFAS, as artificial organofluorine compounds, raise concerns about their bioaccumulation. Suppressing PFAS formation can help reduce environmental impact.

[0284] <<Resin Layer (Hard Coating)>>

[0285] The optical sheet 10 may include a resin layer 30 between the substrate 20 and the functional layer 40. The resin layer 30 comprises a cured product of a curable resin composition. The curable resin composition may include one or more of a thermosetting resin composition and an ionizing radiation curable resin composition. The curable resin composition may include one or more of a thermosetting resin and an ionizing radiation curable compound. The resin layer 30 may be a hard coating. The resin layer 30 can impart high strength and high hardness to the optical sheet 10 and the first surface 11, improving the scratch resistance of the first surface 11. The curable resin composition used in forming the resin layer 30 may be the same as the curable resin composition used to form the functional layer 40. The thermosetting resin and ionizing radiation curable compound used to form the resin layer 30 may be the same as the thermosetting resin and ionizing radiation curable compound used to form the functional layer 40.

[0286] The thickness of the resin layer 30 can be 0.1 μm or more, 0.5 μm or more, or 1 μm or more. The thickness of the resin layer 30 can be less than 100 μm, less than 20 μm, or less than 10 μm. By setting the thickness of the resin layer 30 in this way, excellent scratch resistance can be ensured, and crack formation can be suppressed during processing such as cutting of the optical sheet 10.

[0287] From the perspective of achieving reflection suppression through functional layer 40, the refractive index of resin layer 30 can be higher than that of functional layer 40. The refractive index of resin layer 30 can be above 1.45 and below 1.70.

[0288] When the optical sheet 10 includes a high refractive index layer (described later), the refractive index of the resin layer 30 can be lower than that of the high refractive index layer. In this example, the refractive index of the resin layer 30 can be 1.50 or higher, or 1.55 or higher. In this example, the refractive index of the resin layer 30 can be 1.65 or lower, or 1.60 or lower. By setting the refractive index of the resin layer 30 in this way, the resin layer 30 functions as a medium refractive index layer. The interference between the resin layer 30 as a medium refractive index layer, the second functional layer as a high refractive index layer, and the functional layer as a low refractive index layer becomes possible, further reducing reflectivity. The refractive index of the resin layer 30 can be adjusted by the resin and particles contained in the curable resin composition.

[0289] The refractive index is a value determined by fitting the reflectance spectrum measured by a reflectance photometer to the reflectance spectrum calculated based on an optical model of a multilayer thin film using Fresnel coefficients.

[0290] The resin layer 30 can be made using a coating liquid containing a curable resin composition. The resin layer 30 can be obtained by curing the coating film of the coating liquid. In this example, the coating liquid for making the resin layer 30 may contain additives suitable for use in coating liquids for functional layers. That is, the coating liquid for the resin layer may contain a photopolymerization initiator and a photopolymerization accelerator. The coating liquid for the resin layer may contain a leveling agent.

[0291] <<Second Functional Layer (High Refractive Index Layer)>>

[0292] like Figure 3 As shown, the optical sheet 10 may further include a second functional layer 50. The second functional layer 50 is located between the functional layer 40 and the resin layer 30 in a third direction D3, which is the stacking direction. The second functional layer 50 is configured to have a higher refractive index than the resin layer 30 and the functional layer 40, thereby enhancing the reflection suppression function of the optical sheet 10.

[0293] From the perspective of reflection suppression, the refractive index and average thickness of the second functional layer can be set as follows: The refractive index of the second functional layer can be 1.55 or higher, or 1.56 or higher. The refractive index of the second functional layer can be 1.85 or lower, or 1.75 or lower. The thickness of the second functional layer can be 50 nm or higher. The thickness of the second functional layer can be 200 nm or lower, or 180 nm or lower.

[0294] like Figure 3As shown, the second functional layer 50 may include an adhesive component 51 and particles 52. The adhesive component 51 is the element that retains the particles 52. The adhesive component 51 can function as a binder for forming a coating film. By retaining the particles contained in the second functional layer 50 through the adhesive component 51, the second functional layer 50 can maintain its film morphology. The adhesive component 51 may contain a resin. The adhesive component 51 may be configured in the same way as the adhesive component 41 of the functional layer 40.

[0295] Particle 52 is used to adjust the refractive index and can have an average particle size in the nanometer range. The second functional layer 50 can be made using the same curable resin composition as functional layer 40. The curable resin composition can contain one or more of a thermosetting resin composition and an ionizing radiation curable resin composition. The thermosetting resin and ionizing radiation curable compound used to form the second functional layer 50 can be the same as those used to form functional layer 40.

[0296] Particle 52 can be a particle with a higher refractive index than that of the binder component 51. Examples of particles 52 include antimony pentoxide, zinc oxide, titanium oxide, cerium oxide, tin-doped indium oxide, antimony-doped tin oxide, yttrium oxide, and zirconium oxide. Zirconium oxide, antimony pentoxide, and titanium oxide can impart high strength and high hardness to the second functional layer 50, which helps to improve the scratch resistance of the first surface 11.

[0297] The average particle size of particle 52 can be 5 nm or more, or 10 nm or more. The average particle size of particle 52 can be less than 200 nm, less than 100 nm, or less than 80 nm. The content of particle 52 can be set from the viewpoint of increasing the refractive index of the second functional layer 50 and the strength of the second functional layer 50. The content of particle 52 relative to 100 parts by mass of adhesive component 51 can be 100 parts by mass or more, 300 parts by mass or more, or 500 parts by mass or more. The content of particle 52 relative to 100 parts by mass of adhesive component 51 can be less than 2500 parts by mass, less than 2200 parts by mass, or less than 2000 parts by mass.

[0298] The second functional layer 50 can be made using a coating liquid comprising a curable resin composition and particles 52. The second functional layer 50 can be obtained by curing the coating film of the coating liquid. In this example, the coating liquid used to make the second functional layer 50 may contain additives suitable for use in functional layer coating liquids. That is, the coating liquid for the second functional layer may contain photopolymerization initiators and photopolymerization accelerators. The coating liquid for the second functional layer may contain antistatic agents, antioxidants, surfactants, dispersants, ultraviolet absorbers, leveling agents, etc.

[0299] <<Methods for Manufacturing Optical Sheets>>

[0300] The resin layer 30, functional layer 40, and second functional layer 50 included in the optical sheet 10 can be manufactured using a wet process. In the wet process, a coating liquid containing the components constituting each layer 30, 40, and 50 is prepared. First, the coating liquid is applied to the surface on which each layer 30, 40, and 50 is to be formed. Then, the coating film of the coating liquid is dried and cured to obtain each layer 30, 40, and 50. In addition to the resin composition and particles used to form each layer, the coating liquid may also contain a solvent. The resin composition may contain solid components constituting each layer and additives such as polymerization initiators.

[0301] The optical sheet 10, comprising a substrate 20 and a functional layer 40, can be manufactured as follows: First, a coating liquid for forming the functional layer 40 is prepared. Next, the coating liquid is applied to the substrate 20 to form a coating film. Then, the coating film is dried, and subsequently, it is cured. Thus, the functional layer 40 is formed on the substrate 20, resulting in the optical sheet 10.

[0302] When the optical sheet 10 includes a resin layer 30 in addition to the functional layer 40, the resin layer 30 is formed on the substrate 20 before forming the functional layer 40. The resin layer used to form the resin layer 30 is coated onto the substrate 20 with a coating liquid, and the coating is dried and cured to obtain the resin layer 30. Next, the optical sheet 10 is obtained by forming the functional layer 40 on the resin layer 30. It should be noted that when the resin layer 30 is formed on the substrate 20 in an uncured or semi-cured state and the functional layer 40 is cured, the resin layer 30 and the functional layer 40 can be completely cured together.

[0303] In the case where the optical sheet 10 includes a second functional layer 50 in addition to the resin layer 30 and the functional layer 40, the second functional layer 50 is formed on the resin layer 30 after the resin layer 30 is formed and before the functional layer 40 is formed. The second functional layer for forming the second functional layer 50 is coated onto the resin layer 30 with a coating liquid, and the coating is dried and cured to obtain the second functional layer 50. Next, the optical sheet 10 is obtained by forming the functional layer 40 on the second functional layer 50. It should be noted that when one or more of the resin layer 30 and the second functional layer 50 are formed in an uncured or semi-cured state and the functional layer 40 is cured, one or more of the resin layer 30 and the second functional layer 50 can be completely cured together with the functional layer 40.

[0304] By including a solvent in the coating solution, the viscosity of the coating solution can be adjusted, allowing the various components to dissolve or disperse within it. The solvent can be one or more of the following: ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), carbon halides (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (butanol, cyclohexanol, etc.), cellosolvers (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), glycol ethers (1-methoxy-2-propyl acetate, etc.), and amides (dimethylformamide, dimethylacetamide, etc.).

[0305] When the solvent evaporates too quickly, it actively convections during the drying of the coating solution. The metal oxide particles 42 contained in the coating solution, such as the hollow silica particles 43, move towards the surface of the coating film due to convection caused by solvent evaporation during the drying of the coating solution. These particles moving towards the coating film surface can protrude from the first surface or form protrusions on the first surface 11 in the fabricated optical sheet. In the optical sheet, a large number of metal oxide particles are observed on the first surface 11, and the average area of ​​the Voronoi region decreases.

[0306] From the viewpoint of increasing the average area of ​​the Voronoi region, the coating solution can contain solvents with slow evaporation rates. The relative evaporation rate of the solvent contained in the coating solution can be 70 or less, or 30 to 60. Regarding relative evaporation rates, the evaporation rate of butyl acetate is set to 100, and the evaporation rate of the solvent in question is compared with the evaporation rate of butyl acetate. As an example, the relative evaporation rate of isobutanol is 64. The relative evaporation rate of 1-butanol is 47. The relative evaporation rate of 1-methoxy-2-propyl acetate is 44. The relative evaporation rate of ethyl cellosolve is 38. The relative evaporation rate of cyclohexanone is 32.

[0307] Solvents with a relative evaporation rate of 70 or less can be 10% to 50% by mass or 20% to 40% by mass of the total solvent. In this example, as a solvent other than those with a relative evaporation rate of 70 or less, a solvent with excellent resin solubility can be included in the coating solution. The relative evaporation rate of the solvent with excellent resin solubility can be 100 or more.

[0308] As a solvent with a relatively slow evaporation rate, a high-boiling-point solvent can be used. Examples of high-boiling-point solvents include PMA:propylene glycol monomethyl ether acetate. Examples of solvents with a boiling point higher than PMA include diacetone alcohol. Examples of solvents with a boiling point higher than diacetone alcohol include benzyl acetate. By using a coating solution for forming a functional layer containing more high-boiling-point solvents, the average area of ​​the Voronoi region can be increased.

[0309] The drying temperature during coating liquid drying can also be adjusted. The airflow and speed of the drying air during coating liquid drying can also be adjusted. By adjusting the drying conditions, the movement of metal oxide particles 42 towards the surface of the coating film during coating liquid drying can also be suppressed. Therefore, in the manufactured optical film, the protrusion of metal oxide particles 42 from the first surface and the formation of protrusions on the first surface 11 can be suppressed. As a result, the average area of ​​the Voronoi region can be increased.

[0310] By reducing drying conditions, rapid solvent evaporation can be suppressed. The generation of strong upward currents within the coating film can be suppressed. Therefore, the aggregation of metal oxide particles 42 on the coating surface can be suppressed. This, in turn, increases the average area of ​​the Voronoi region.

[0311] Drying conditions can be appropriately selected based on the characteristics of the materials used. When using a coating solution that easily penetrates the substrate, the drying time can be shortened. By reducing the amount of penetration into the substrate, the aggregation of metal oxide particles 42 on the coating surface can be suppressed. When using easily agglomerated metal oxide particles 42, shortening the drying time can suppress the aggregation of metal oxide particles 42 on the coating surface. This increases the average area of ​​the Voronoi region.

[0312] Furthermore, heating the substrate 20 during the drying of the coating liquid can promote the penetration of the coating liquid into the substrate 20. Therefore, by gradually increasing the drying temperature, the coating liquid can be dried while inhibiting its penetration into the substrate 20. Additionally, the drying conditions can be changed in the first and second halves of the drying process.

[0313] Furthermore, the proportion of solid components in the coating liquid for forming the functional layer can be adjusted. If the proportion of solid components increases, the viscosity of the coating liquid for forming the functional layer increases. According to this example, it is easy to maintain the state of the resin adhering to the metal oxide particles 42. Therefore, in the manufactured optical film, it is possible to suppress the metal oxide particles 42 from protruding from the first surface and forming protrusions on the first surface 11. As a result, the average area of ​​the Voronoi region can be increased.

[0314] If the proportion of solids decreases, the drying time becomes longer. Even when the proportion of solids decreases, the average area of ​​the Voronoi region can increase in combination with other conditions.

[0315] Examples of methods for curing coatings that form various layers include irradiation with ionizing radiation such as ultraviolet light and electron beams, and heating. Curing processes using ionizing radiation can cure in a short time, and in this respect, they offer excellent productivity.

[0316] As described above, optical sheet 10 can be manufactured.

[0317] As explained above, by adjusting the type of solvent, the mixing, and the drying conditions of the coating, the average area of ​​the Voronoi region, with the metal oxide particles 42 observed on the first surface 11 as the parent point, can be increased. However, the average area of ​​the Voronoi region can be increased by other methods, either alternatively or in addition to these methods. For example, the optical sheet 10 may include an outer coating. The outer coating may be disposed overlapping the functional layer 40. The outer coating may cover the metal oxide particles located on the surface of the functional layer 40. The outer coating may constitute the first surface 11 of the optical sheet 10. That is, the functional layer 40 may also be located between the outer coating and the substrate 20 in the first direction D1. The thickness of the outer coating may be thinner than the thickness of the functional layer 40.

[0318] The average area of ​​the Voronoi region can also be adjusted by the affinity between the metal oxide particles 42 and the adhesive component 41. By using the adhesive component 41, which has a high affinity for the metal oxide particles 42, the adhesive component 41 easily surrounds the metal oxide particles 42. This prevents the metal oxide particles 42 from protruding from the adhesive component 41 or forming protrusions on the first surface 11. By combining the metal oxide particles 42 and the adhesive component 41, the average area of ​​the Voronoi region can be increased.

[0319] The average area of ​​the Voronoi region can also be adjusted based on the affinity between the metal oxide particles 42 included in the functional layer 40. By using a variety of metal oxide particles 42 with appropriate affinity, the metal oxide particles 42 can be uniformly dispersed within the binder component 41. This prevents the metal oxide particles 42 from protruding from the binder component 41 or forming protrusions on the first surface 11. The average area of ​​the Voronoi region can be increased by the combination of metal oxide particles 42 included in the functional layer 40.

[0320] According to the above-described wet-process-based manufacturing method of the optical sheet 10, such as Figure 4 As shown, a strip-shaped article 5 containing multiple optical sheets 10 can be manufactured. Optical sheets 10 are obtained by cutting the strip-shaped article 5 to a predetermined size. According to this example, optical sheets 10 of various sizes can be obtained from the strip-shaped article 5 as needed. Therefore, optical sheets 10 of various sizes can be provided as needed. Figure 4As shown, by processing the sheet article 5 as a roll 7 wound around the winding core with the winding axis RA as the center, the processability of the sheet article 5 can be improved.

[0321] In addition to the steps described above for manufacturing an optical sheet, the method for manufacturing an optical sheet may also include a step of selecting the optical sheet 10 to be manufactured. The step of selecting the optical sheet 10 may further include measuring the average area of ​​the Voronoi region with the metal oxide particles observed on the first surface 11 as parent points, and selecting the average area (nm) of the Voronoi region. 2 The step involves using an optical film with a specified value above a certain threshold. Here, the specified value can be 2500 nm. 2 The average area of ​​the Voronoi region, with the metal oxide particles observed on the first surface as the parent point, is 2500 nm. 2 The optical sheets described above exhibit excellent scratch resistance. Following this selection procedure, optical sheets with excellent scratch resistance can be selected with high precision without performing scratch tests using materials such as steel wool.

[0322] <<<Polarizing Film 60>>>

[0323] The optical element 10 in this embodiment can be applied to the polarizer 60. Figure 5 In the example shown, polarizer 60 includes a first protective sheet 61, a polarizing element 62, and a second protective sheet 63. The first protective sheet 61 and the second protective sheet 63 sandwich the polarizing element 62 in the middle and cover it from both sides. At least one of the first protective sheet 61 and the second protective sheet 63 may contain an optical sheet 10. If only one of the first protective sheet 61 and the second protective sheet 63 contains an optical sheet 10, the other protective sheet may contain a substrate 20.

[0324] Polarizing element 62 allows one linearly polarized light component to pass through while blocking another linearly polarized light component. Polarizing element 62 can also be an absorptive polarizing element that absorbs the other linearly polarized light component. Polarizing element 62 can also be a reflective polarizing element that reflects the other linearly polarized light component. Polarizing element 62 can also be a sheet-type polarizing element, such as a polyvinyl alcohol film, polyvinyl formal film, polyvinyl acetal film, or ethylene-vinyl acetate copolymer saponified film, which has been dyed and stretched using iodine or the like. Polarizing element 62 can also be a wire grid type polarizing element composed of multiple parallel metal wires. Polarizing element 62 can be a coated polarizing element coated with lyotropic liquid crystal or dichroic guest-host material, or a multilayer thin film type polarizing element.

[0325] <<<Image display device 65>>>

[0326] The optical sheet 10 of this embodiment can be applied to a display device 65. Figure 6In the example shown, the display device 65 includes an image forming apparatus 66 and an optical sheet 10. The image forming apparatus 66 has a display surface 66a for displaying an image. The optical sheet 10 overlaps with the image forming apparatus 66 such that its second surface 12 faces the display surface 66a. The optical sheet 10 may also be bonded to the image forming apparatus 66 by a bonding layer containing an adhesive material, bonding agent, etc. An observer can clearly observe the image displayed by the image forming apparatus 66 through the optical sheet 10 while suppressing reflection from the first surface 11 of the optical sheet 10. The image forming apparatus 66 is not particularly limited. Examples of image forming apparatus 66 include liquid crystal display elements, EL display elements, plasma display elements, electronic paper elements, etc.

[0327] <<<Panel 70>>>

[0328] The optical sheet 10 of this embodiment can be applied to various purposes. Figure 7 A panel 70 with an optical sheet 10 is shown. The panel 70 includes the optical sheet 10 and a bonded article 71 to which the optical sheet 10 is bonded. The panel 70 constitutes a reflection-suppressing article with the function of suppressing reflection through the optical sheet 10. The optical sheet 10 overlaps with the bonded article 71 face-to-face with its second surface 12. The optical sheet 10 may also be bonded to the bonded article 71 by means of a bonding layer including adhesive material, bonding agent, etc. Examples of the bonded article 71 include dashboards, clocks, display cases, shop windows, and windows.

[0329] Example

[0330] This disclosure is illustrated in more detail by way of examples. This disclosure is not limited to the following examples.

[0331] <<<1. Fabrication of Optical Sheets>>>

[0332] Optical sheets of Examples 1-8 and Comparative Examples 1-3 were prepared.

[0333] <<Example 1>>

[0334] Coating solution 1 for resin layer (HC layer coating solution 1) of the following formulation was applied to a triacetyl cellulose substrate with a thickness of 80 μm. Next, the coating film of resin layer coating solution 1 was dried at 70°C for 1 minute to allow solvent evaporation. Then, it was subjected to ultraviolet light at 100 mJ / cm². 2 The cumulative light intensity was used to irradiate the resin layer with coating liquid 1. Through the above operations, a resin layer (hard coating) with a dry thickness of 10 μm was formed on the substrate.

[0335] Next, a coating liquid 1 for the functional layer (coating liquid 1 for the low refractive index layer) of the following formulation is applied onto the resin layer. Then, the coating film of the functional layer coating liquid 1 is dried at 50°C for 30 seconds (drying air velocity 0.5 m / s), and further dried at 50°C for 30 seconds (drying air velocity 5 m / s) to allow the solvent to evaporate. Next, a cumulative light intensity of 200 mJ / cm² is measured. 2 The coating film of the functional layer using coating liquid 1 is irradiated with ultraviolet light. As a result, a functional layer (low refractive index layer) with a dry thickness of 100 nm is formed, and the optical sheet of Example 1 is obtained.

[0336] <Coating solution 1 for resin layer (Coating solution 1 for hard coating layer)>

[0337] · 145 parts by weight of solid silica granules

[0338] (Particles with an average particle size of 12.5 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 46%)

[0339] • 100 parts by weight of a composition containing UV-curable acrylate

[0340] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-450", solid content 100%)

[0341] • 42 parts by weight of a composition containing UV-curable acrylate

[0342] (Made by First Industrial Corporation, trade name "NewFrontier R-1403MB", 80% solid content)

[0343] · 11 parts by weight of photopolymerization initiator

[0344] (IGM Resins, trade name "Omnirad184", 100% solids)

[0345] · 6 parts by weight of silicone-based leveling agent

[0346] (Manufactured by Dai Nippon Seika Co., Ltd., trade name "10-301", solid content 5%)

[0347] · Methyl isobutyl ketone (MIBK) 238 parts by weight

[0348] · 200 parts by weight of methyl ethyl ketone (MEK)

[0349] 40 parts by weight of propylene glycol monomethyl ether (PGME)

[0350] <Coating solution 1 for functional layer (Coating solution 1 for low refractive index layer)>

[0351] · 2633 parts by weight of hollow silica particles

[0352] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0353] 117 parts by weight of solid silica granules

[0354] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0355] • 229 parts by weight of a composition containing a UV-curable siloxane compound

[0356] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI-20", 100% solids)

[0357] • 100 parts by weight of a composition containing UV-curable acrylate

[0358] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0359] · 13 parts by weight of photopolymerization initiator

[0360] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0361] · Leveling agent 1371 parts by weight

[0362] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0363] Methyl isobutyl ketone (MIBK) 40663 parts by weight

[0364] ·Propylene glycol monomethyl ether acetate (PMA) 4879 parts by weight

[0365] <<Example 2>>

[0366] Example 2 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 2 described below. Otherwise, the optical sheet of Example 2 was obtained using the same materials and the same methods as in Example 1.

[0367] <Coating solution 2 for functional layer (Coating solution 2 for low refractive index layer)>

[0368] · 2633 parts by weight of hollow silica particles

[0369] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0370] 117 parts by weight of solid silica granules

[0371] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0372] • 229 parts by weight of a composition containing a UV-curable siloxane compound

[0373] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0374] • 100 parts by weight of a composition containing UV-curable acrylate

[0375] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0376] · 13 parts by weight of photopolymerization initiator

[0377] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0378] · Leveling agent 1371 parts by weight

[0379] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0380] Methyl isobutyl ketone (MIBK) 35873 parts by weight

[0381] ·Propylene glycol monomethyl ether acetate (PMA) 9758 parts by weight

[0382] <<Example 3>>

[0383] Example 3 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 3 described below. Otherwise, the optical sheet of Example 3 was obtained using the same materials and the same method as in Example 1.

[0384] <Coating solution 3 for functional layers (Coating solution 3 for low refractive index layers)>

[0385] · 2633 parts by weight of hollow silica particles

[0386] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0387] 117 parts by weight of solid silica granules

[0388] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0389] • 229 parts by weight of a composition containing a UV-curable siloxane compound

[0390] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0391] • 100 parts by weight of a composition containing UV-curable acrylate

[0392] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0393] · 13 parts by weight of photopolymerization initiator

[0394] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0395] · Leveling agent 1371 parts by weight

[0396] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0397] Methyl isobutyl ketone (MIBK) 30904 parts by weight

[0398] ·Propylene glycol monomethyl ether acetate (PMA) 14642 parts by weight

[0399] <<Example 4>>

[0400] Example 4 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 4 described below. Otherwise, the optical sheet of Example 4 was obtained using the same materials and the same methods as in Example 1.

[0401] <Coating solution 4 for functional layers (Coating solution 4 for low refractive index layers)>

[0402] · 2633 parts by weight of hollow silica particles

[0403] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0404] 117 parts by weight of solid silica granules

[0405] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0406] • 229 parts by weight of a composition containing a UV-curable siloxane compound

[0407] (Manufactured by Toa Synthetic Co., Ltd., trade name "AAC-SQ SI20", 100% solids)

[0408] • 100 parts by weight of a composition containing UV-curable acrylate

[0409] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0410] · 13 parts by weight of photopolymerization initiator

[0411] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0412] · Leveling agent 1371 parts by weight

[0413] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0414] Methyl isobutyl ketone (MIBK) 30904 parts by weight

[0415] · Diacetone alcohol 14642 parts by weight

[0416] <<Example 5>>

[0417] Example 5 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 5 described below. Otherwise, the optical sheet of Example 5 was obtained using the same materials and the same method as in Example 1.

[0418] <Coating solution 5 for functional layers (Coating solution 5 for low refractive index layers)>

[0419] · 2687 parts by weight of hollow silica particles

[0420] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0421] 117 parts by weight of solid silica granules

[0422] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0423] • 236 parts by weight of a composition containing a UV-curable siloxane compound

[0424] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0425] • 100 parts by weight of a composition containing UV-curable acrylate

[0426] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0427] · 13 parts by weight of photopolymerization initiator

[0428] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0429] · Leveling agent 1398 parts by weight

[0430] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0431] · Methyl isobutyl ketone (MIBK) 13687 parts by weight

[0432] 7291 parts by weight of diacetone alcohol

[0433] <<Example 6>>

[0434] Example 6 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 6 described below. Otherwise, the optical sheet of Example 6 was obtained using the same materials and the same methods as in Example 1.

[0435] <Coating solution 6 for functional layers (Coating solution 6 for low refractive index layers)>

[0436] · 2687 parts by weight of hollow silica particles

[0437] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0438] 117 parts by weight of solid silica granules

[0439] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0440] • 236 parts by weight of a composition containing a UV-curable siloxane compound

[0441] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0442] • 100 parts by weight of a composition containing UV-curable acrylate

[0443] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0444] · 13 parts by weight of photopolymerization initiator

[0445] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0446] · Leveling agent 1398 parts by weight

[0447] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0448] · Methyl isobutyl ketone (MIBK) 13687 parts by weight

[0449] 7291 parts by weight of benzyl acetate

[0450] <<Example 6A>>

[0451] Example 6A differs from Example 6 above in that the coating liquid 1 for the functional layer is changed to the coating liquid 6A for the functional layer described below. Otherwise, the optical sheet of Example 6A was obtained using the same materials and the same methods as in Example 6.

[0452] <Coating solution 6A for functional layers (Coating solution 6A for low refractive index layers)>

[0453] · 2642 parts by weight of hollow silica particles

[0454] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0455] · 116 parts by weight of solid silica granules

[0456] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0457] · 193 parts by weight of alumina particles

[0458] (Particles with an average particle size of 15.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 30%)

[0459] • 231 parts by weight of a composition containing a UV-curable siloxane compound

[0460] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0461] • 100 parts by weight of a composition containing UV-curable acrylate

[0462] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0463] · 13 parts by weight of photopolymerization initiator

[0464] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0465] · Leveling agent 1462 parts by weight

[0466] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0467] · Methyl isobutyl ketone (MIBK) 14296 parts by weight

[0468] 7616 parts by weight of benzyl acetate

[0469] <<Example 6B>>

[0470] Example 6B differs from Example 6 in that a second functional layer (high refractive index layer) is formed between the functional layer and the resin layer. Otherwise, the optical sheet of Example 6B is obtained using the same materials and the same methods as in Example 6.

[0471] Specifically, the optical film of Example 6B was fabricated below. A resin layer was formed on a substrate using the same materials and methods as in Example 1. Next, a second functional layer coating liquid 1 (high refractive index layer coating liquid 1) of the following formulation was applied to the resin layer. Then, the coating film of the second functional layer coating liquid 1 was dried at 70°C for 1 minute to allow the solvent to evaporate. Next, the coating film of the second functional layer coating liquid 1 was subjected to a cumulative light intensity of 100 mJ / cm². 2 Ultraviolet light was applied. This formed a second functional layer (high refractive index layer) with a dry thickness of 150 nm. Then, using the same materials and methods as in Example 1, a functional layer (low refractive index layer) was formed on the second functional layer to obtain the optical sheet of Example 6B.

[0472] <Coating solution 1 for the second functional layer (Coating solution 1 for the high refractive index layer)>

[0473] · 429 parts by mass of high refractive index particles

[0474] (Nippon Shokubai Co., Ltd., product name "Zircostar", 70% solid content)

[0475] • 100 parts by weight of a composition containing a UV-curable siloxane compound

[0476] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0477] · 16 parts by weight of photopolymerization initiator

[0478] (Product manufactured by IGM Resins under the brand name "Omnirad127", 100% solid content)

[0479] · 8 parts by weight of silicone-based leveling agent

[0480] (Manufactured by Dai Nippon Seika Co., Ltd., trade name "10-301", solid content 5%)

[0481] 5779 parts by weight of methyl isobutyl ketone

[0482] ·Propylene glycol monomethyl ether (PGME) 5914 parts by weight

[0483] <<Example 7>>

[0484] Example 7 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 7 described below. Otherwise, the optical sheet of Example 7 is obtained using the same materials and the same methods as in Example 1.

[0485] <Coating solution 7 for functional layers (Coating solution 7 for low refractive index layers)>

[0486] · 2687 parts by weight of hollow silica particles

[0487] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0488] 117 parts by weight of solid silica granules

[0489] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0490] • 236 parts by weight of a composition containing a UV-curable siloxane compound

[0491] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0492] • 100 parts by weight of a composition containing UV-curable acrylate

[0493] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0494] · 13 parts by weight of photopolymerization initiator

[0495] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0496] · Leveling agent 1398 parts by weight

[0497] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0498] · Methyl isobutyl ketone (MIBK) 11255 parts by weight

[0499] · Benzyl acetate 9723 parts by weight

[0500] <<Example 8>>

[0501] Example 8 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 8 described below. Otherwise, the optical sheet of Example 8 is obtained using the same materials and the same methods as in Example 1.

[0502] <Coating solution 8 for functional layers (Coating solution 8 for low refractive index layers)>

[0503] · 2669 parts by weight of hollow silica particles

[0504] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0505] 117 parts by weight of solid silica granules

[0506] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0507] • 234 parts by weight of a composition containing a UV-curable siloxane compound

[0508] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0509] • 100 parts by weight of a composition containing UV-curable acrylate

[0510] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0511] · 13 parts by weight of photopolymerization initiator

[0512] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0513] · Leveling agent 1389 parts by weight

[0514] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0515] · Methyl isobutyl ketone (MIBK) 6106 parts by weight

[0516] · 6273 parts by weight of benzyl acetate

[0517] <<Comparative Example 1>>

[0518] Comparative Example 1 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 9 described above. Otherwise, the optical sheet of Comparative Example 1 is obtained using the same materials and the same methods as in Example 1.

[0519] <Coating solution 9 for functional layers (Coating solution 9 for low refractive index layers)>

[0520] · 2645 parts by weight of hollow silica particles

[0521] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0522] 117 parts by weight of solid silica granules

[0523] (Particles with an average particle size of 9.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 50%)

[0524] · 193 parts by weight of alumina particles

[0525] (Particles with an average particle size of 15.0 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 30%)

[0526] • 231 parts by weight of a composition containing a UV-curable siloxane compound

[0527] (Manufactured by Toa Synthetic Co., Ltd., trade name "MAC-SQ SI20", 100% solids)

[0528] • 100 parts by weight of a composition containing UV-curable acrylate

[0529] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0530] · 14 parts by weight of photopolymerization initiator

[0531] (IGM Resins, product name "Esacure 1001M", 100% solids)

[0532] · 97 parts by weight of silicone-based leveling agent

[0533] (Manufactured by Dai Nippon Seika Co., Ltd., trade name "10-301", solid content 5%)

[0534] Methyl isobutyl ketone (MIBK) 37986 parts by weight

[0535] Comparative Example 2

[0536] Comparative Example 2 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 10 described above. Otherwise, the optical sheet of Comparative Example 2 is obtained using the same materials and the same methods as in Example 1.

[0537] <Coating solution 10 for functional layers (Coating solution 10 for low refractive index layers)>

[0538] · 374 parts by weight of hollow silica particles

[0539] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0540] 120 parts by weight of solid silica granules

[0541] (Particles with an average particle size of 12.5 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 46%)

[0542] • 100 parts by weight of a composition containing UV-curable acrylate

[0543] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0544] · 4 parts by weight of photopolymerization initiator

[0545] (IGM Resins, trade name "Omnirad127", 100% solids)

[0546] · Leveling agent 115 parts by weight

[0547] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0548] Methyl isobutyl ketone (MIBK) 8544 parts by weight

[0549] ·Propylene glycol monomethyl ether acetate (PMA) 1000 parts by weight

[0550] Comparative Example 3

[0551] Comparative Example 3 differs from Example 1 in that the functional layer coating liquid 1 is changed to the functional layer coating liquid 11 described above. Otherwise, the optical sheet of Comparative Example 3 is obtained using the same materials and the same methods as in Example 1.

[0552] <Coating solution 11 for functional layers (Coating solution 11 for low refractive index layers)>

[0553] · 603 parts by weight of hollow silica particles

[0554] (Particles with an average particle size of 65 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 20%)

[0555] · 54 parts by weight of solid silica granules

[0556] (Particles with an average particle size of 12.5 nm, surface-treated with a silane coupling agent containing methacrylamide groups, and a solid content of 46%)

[0557] • 100 parts by weight of a composition containing UV-curable acrylate

[0558] (Manufactured by Toagosei Co., Ltd., trade name "ARONIX M-305", solid content 100%)

[0559] · 4 parts by weight of photopolymerization initiator

[0560] (IGM Resins, trade name "Omnirad127", 100% solids)

[0561] · Leveling agent 123 parts by weight

[0562] (Shin-Etsu Chemical Industry Co., Ltd., trade name "X-71-1203M", solid content 20%)

[0563] · Methyl isobutyl ketone (MIBK) 8296 parts by weight

[0564] ·Propylene glycol monomethyl ether acetate (PMA) 990 parts by weight

[0565] <<<2. Measurement and Evaluation>>>

[0566] As described below, the optical sheets of the Examples and Comparative Examples were measured and evaluated. The test environment for each measurement and evaluation was set at a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. Before each measurement and evaluation, the samples to be tested were placed in the above test environment for 16 hours.

[0567] <<2-1. Visual Reflectivity Y>>

[0568] Samples measuring 5cm × 5cm were cut from the optical sheets of the examples and comparative examples. The samples were visually inspected to ensure they were free of dust, scratches, or other abnormalities. The apparent reflectance Y (%) of each example's optical sheet was measured using the method described above. The apparent reflectance Y was measured using a UV-Vis-NIR spectrophotometer "V780" manufactured by Nippon Spectrophotometer Co., Ltd. The results of the apparent reflectance Y measurement are shown in Table 1.

[0569] <<2-2. Total Light Transmittance>>

[0570] Samples measuring 10cm × 5cm were cut from the optical sheets of the examples and comparative examples. The samples were visually inspected to ensure they were free of dust, scratches, or other abnormalities. The total light transmittance (%) of each example's optical sheet was measured using the method described above. The total light transmittance was measured using a haze meter "HM-150" manufactured by Murakami Color Technology Research Institute. The results of the total light transmittance measurements are shown in Table 1.

[0571] <<2-3. Transmitted Haze Value>>

[0572] Samples measuring 10cm × 5cm were cut from the optical films of the examples and comparative examples. The samples were visually inspected to ensure they were free of dust, scratches, or other abnormalities. The transmittance haze (%) of each example's optical film was measured using the method described above. The transmittance haze was measured using a haze meter "HM-150" manufactured by Murakami Color Technology Research Institute. The results of the transmittance haze measurements are shown in Table 1.

[0573] <<2-4. Average area of ​​the Voronoi region>>

[0574] Samples measuring 5mm × 5mm were cut from the optical sheets of the examples and comparative examples. The samples were visually confirmed to be free of dust, scratches, or other abnormalities. Using the method described above, the average area (nm) of the Voronoi region, with the metal oxide particles observed on the first surface as the mother point, was measured for each example's optical sheet. 2 ).

[0575] First, an observation image of the first side was obtained using a scanning electron microscope (SEM). The scanning electron microscope used was a Hitachi High-Tech SU-9000 ultra-high resolution field emission scanning electron microscope. As an example, the observation image of Example 1 obtained using a scanning electron microscope is shown below. Figure 8A .

[0576] Next, the images acquired using the scanning electron microscope were binarized using the image processing software "ImageJ" and "Fiji". As an example, in... Figure 8B The image shown is of the first face after binarization processing for Example 1. Figure 8B The image shown is obtained by analyzing... Figure 8A The image of the first side shown is obtained by binarizing it.

[0577] Then, using "ImageJ" and "Fiji", the mother point is determined based on the position of the metal oxide particles observed on the first surface 11, according to the binarized image. As an example, in... Figure 8C The diagram shows the distribution of the mother points determined for Example 1. Figure 8C The mother point distribution shown is based on Figure 8B It was generated from the observation image of the first side shown.

[0578] Next, using the image processing software "ImageJ" and "Fiji", a Voronoi map was created. Then, the area (nm) of the Voronoi region was determined from the obtained Voronoi map. 2 The average area (nm) of the Voronoi region was calculated from the area measurement results. 2 The standard deviation (nm) of the area of ​​the Voronoi region was calculated from the area measurement results. 2 The ratio of the standard deviation of the area of ​​the Voronoi region to the average area of ​​the Voronoi region was calculated. The average area of ​​the Voronoi region (nm) 2 Standard deviation of the area of ​​the Voronoi region (nm) 2 The ratio of the standard deviation of the area of ​​the Voronoi region to the average area of ​​the Voronoi region is shown in the columns “Average Area”, “Standard Deviation”, and “Standard Deviation / Average Area” of Table 1.

[0579] Figures 9A to 9E The Voronoi diagrams obtained from the observation images of the first side of the optical sheets of Examples 1 to 5 are shown respectively. Figure 9F and Figure 9G The Voronoi diagrams obtained from the observation images of the first side of the optical plates of Comparative Examples 1 and 2 are shown respectively. Figure 9AThe Voronoi diagram shown is based on Figure 8C The parent point distribution shown is generated.

[0580] <<2-5. Coefficient of kinetic friction>>

[0581] Samples measuring 15cm × 25cm were cut from the optical sheets of the examples and comparative examples. The samples were visually inspected to ensure they were free of dust, scratches, or other abnormalities. The coefficient of kinetic friction of each optical sheet was measured using the method described above. For the measurement of the coefficient of kinetic friction, a friction coefficient measuring device, which is a friction test fixture available from Shimadzu Corporation, was incorporated into the small benchtop testing machine "EZ-LX" manufactured by Shimadzu Corporation. The results of the coefficient of kinetic friction measurement are shown in Table 1.

[0582] <<2-6. Steel wool abrasion resistance test>>>

[0583] Samples measuring 50mm × 100mm were cut from the optical sheets of the examples and comparative examples. The samples were visually inspected to ensure they were free of dust, scratches, or other abnormalities. A steel wool abrasion resistance test was then performed on the optical sheets of each example using the method described above. The steel wool abrasion resistance test was conducted using a vibratory friction fastness tester “AB-301-S” manufactured by TESTER SANGYO Co., Ltd.

[0584] The steel wool abrasion resistance test samples that had undergone 1000 cycles under a load of 1000g were removed from the testing machine, and the surface of the sample consisting of the first side of the optical sheet was observed under the aforementioned observation conditions. Each sample was evaluated according to the following criteria. In the following criteria, "0" represents the highest abrasion resistance, decreasing from "0" to "5". Five samples were evaluated for each example, and the worst evaluation result for each example is shown in Table 1. The example shown in Table 1 is where all five samples were evaluated as "0". "0", "1", "2", or "3" will not be a problem when applied to display devices. Therefore, optical sheets evaluated as "0", "1", "2", or "3" are considered resistant to the steel wool abrasion resistance test. Optical sheets evaluated as "4" or "5" are considered not resistant to the steel wool abrasion resistance test. It should be noted that the test conditions of "1000g load, 1000 cycles" in the steel wool abrasion resistance test are more stringent than the conditions usually required for anti-reflective films (AR films, LR films) attached to the display surface of display devices.

[0585] (Evaluation Criteria)

[0586] 5: This resulted in the stripping of the functional layer.

[0587] 4: Damage was observed that caused problems when applied to display devices.

[0588] 3: Patterns such as discoloration and shallow scratches caused by deformation of the hollow silica are observed on the surface. These discoloration and patterns are at a level that will not cause problems when applied to display devices.

[0589] 2: Discoloration was observed on the surface due to deformation of the hollow silica, but no scratches or patterns were observed. The discoloration is to a degree that will not cause problems when applied to a display device.

[0590] 1: A slight color change can be confirmed through careful observation, but it is not obvious in normal observation.

[0591] 0: No discoloration, patterns, or other changes were observed.

[0592] <<2-7. Rubber Abrasion Resistance Test (CS6 Abrasion Resistance Test)>>

[0593] 50mm × 100mm samples were cut from the optical sheets of the examples and comparative examples. The samples were visually confirmed to be free of dust, scratches, or other abnormalities. Rubber abrasion resistance tests were performed on the optical sheets of each example using the method described above. As mentioned above, the sliding sheet was a "Jumbo Wearaser CS-6" manufactured by TABER Corporation (registered trademark). The rubber abrasion resistance test was performed using a vibration-type friction fastness tester "AB-301-S" manufactured by TESTERSANGYO Co., Ltd.

[0594] Samples that had undergone 1000 cycles of abrasion resistance testing under a load of 1000g were removed from the testing machine, and the surface of the sample, consisting of the first side of the optical sheet, was observed under the aforementioned observation conditions. Each sample was evaluated according to the following criteria. In the following criteria, "0" represents the highest abrasion resistance, decreasing from "0" to "5". Five samples were evaluated for each example, and the worst evaluation result for each example is shown in Table 1. The example shown in Table 1 is where all five samples were evaluated as "0". "0", "1", "2", or "3" will not be a problem when applied to display devices. Therefore, optical sheets evaluated as "0", "1", "2", or "3" are considered resistant to this abrasion resistance test. Optical sheets evaluated as "4" or "5" are considered not resistant to this abrasion resistance test.

[0595] (Evaluation Criteria)

[0596] 5: This resulted in the stripping of the functional layer.

[0597] 4: Damage was observed that caused problems when applied to display devices.

[0598] 3: Patterns such as discoloration and shallow scratches caused by deformation of the hollow silica are observed on the surface. These discoloration and patterns are at a level that will not cause problems when applied to display devices.

[0599] 2: Discoloration was observed on the surface due to deformation of the hollow silica, but no scratches or patterns were observed. The discoloration is to a degree that will not cause problems when applied to a display device.

[0600] 1: A slight color change can be confirmed through careful observation, but it is not obvious in normal observation.

[0601] 0: No discoloration, patterns, or other changes were observed.

[0602]

[0603] Symbol Explanation

[0604] 5: Sheet article; 6: Winding core; 7: Roll; 10: Optical sheet; 11: First surface; 12: Second surface; 20: Substrate; 30: Resin layer; 40: Functional layer; 41: Adhesive component; 42: Metal oxide particles; 43: Hollow silica particles; 44: Solid silica particles; 50: Second functional layer; 51: Adhesive component; 52: Particle; 60: Polarizer; 61: First protective sheet; 62: Polarizing element; 63: Second protective sheet; 65: Display device; 66: Image forming apparatus; 66a: Display surface; 70: Panel; 71: Article to be bonded.

Claims

1. An optical sheet comprising a first surface and a second surface opposite to the first surface, wherein, The optical sheet comprises a substrate and a functional layer sequentially from the second surface toward the first surface. The functional layer comprises adhesive components and metal oxide particles. The average area of ​​the Voronoi region, with the metal oxide particles observed on the first surface as the parent point, is 2500 nm. 2 above.

2. The optical sheet according to claim 1, wherein, The average area of ​​the Voronoi region is 3200 nm. 2 above.

3. The optical sheet according to claim 1, wherein, The standard deviation of the area of ​​the Voronoi region is 950 nm. 2 above.

4. The optical sheet according to claim 1, wherein, The ratio of the standard deviation of the area of ​​the Voronoi region to the average area of ​​the Voronoi region is greater than 0.

30.

5. The optical sheet according to claim 1, wherein, Use the "Registered Trademark: Jumbo Wearaser, Model: CS-6" manufactured by TABER as the sliding piece. The coefficient of kinetic friction between the first surface and the sliding plate to which a load of 200g is applied is less than 0.

95.

6. The optical sheet according to claim 1, wherein, The optical sheet exhibits resistance to abrasion tests conducted on its first surface using steel wool under the following conditions. Abrasion resistance test: Using steel wool #0000 as the sliding plate, the test was repeated 1000 times with a load of 1000g, a moving speed of 80mm / second, and a single-pass moving distance of 40mm.

7. The optical sheet according to claim 1, wherein, The optical sheet exhibits resistance to abrasion tests conducted on its first surface using rubber under the following conditions. Abrasion resistance test: Using the "registered trademark: Jumbo Wearaser, model: CS-6" manufactured by TABER as the sliding pad, the test was performed 150 times with a load of 200g, a moving speed of 200mm / second, and a single-pass moving distance of 50mm.

8. The optical sheet according to claim 1, wherein, The functional layer comprises hollow silica particles.

9. The optical sheet according to claim 1, wherein, The functional layer contains alumina particles.

10. The optical sheet according to claim 1, wherein, The functional layer contains siloxane compounds.

11. The optical sheet according to claim 1, wherein, The optical sheet includes a resin layer located between the substrate and the functional layer. The resin layer comprises a cured product of a curable resin composition.

12. A sheet article comprising a plurality of optical sheets as described in any one of claims 1 to 11.

13. The sheet article according to claim 12, wherein, The sheet of material is wound around the winding axis.

14. A polarizer comprising a first protective sheet, a polarizing element, and a second protective sheet. At least one of the first protective sheet and the second protective sheet comprises the optical sheet according to any one of claims 1 to 11.

15. A display device comprising: Image forming apparatus; and The optical sheet according to any one of claims 1 to 11 that overlaps with the image forming apparatus.

16. A panel comprising: The joined items; and The optical sheet according to any one of claims 1 to 11 that is joined to the article being joined.

17. A method for selecting an optical sheet, comprising: For an optical sheet, the step of measuring the average area of ​​a Voronoi region with metal oxide particles observed on a first surface as mother points, the optical sheet having a first surface and a second surface opposite the first surface, and having a substrate and a functional layer sequentially disposed from the second surface toward the first surface, the functional layer comprising an adhesive component and metal oxide particles; and The step of selecting an optical sheet whose average area of ​​the Voronoi region is above a predetermined value, wherein the average area of ​​the Voronoi region is in nm. 2 .

18. A method for manufacturing an optical sheet, comprising: The steps of manufacturing an optical sheet include: the optical sheet having a first surface and a second surface opposite to the first surface; a substrate and a functional layer being sequentially formed from the second surface toward the first surface; the functional layer comprising an adhesive component and metal oxide particles; and... The step of selecting an optical sheet with an average area of ​​the Voronoi region, which is defined as the mother point of the metal oxide particles observed on the first surface, being greater than or equal to a predetermined value, wherein the average area of ​​the Voronoi region is in nm. 2 .

Images