Optical film, and polarizing plate, surface plate, image display panel, and image display device that use said optical film

Abstract

Provided is an optical film that can suppress viewing angle-dependent variations in color tone as well as the visual recognition of lines in a screen. An optical film 100 has a first surface S1 and a second surface S2 that is a surface on the opposite side from the first surface. The optical film 100 has an antireflection layer 30 and an antiglare layer 20 in this order from the first surface S1 toward the second surface S2. The first surface S1 has an uneven shape and the Δab represented by the following formula is 0.20-2.50.　Δab = {(an - an+1)2 + (bn - bn+1)2}1 / 2 (In the formula, an represents the a* value in the Lab color system calculated from the reflected light in the n-th measurement direction in a first measurement; an+1 represents the a* value in the Lab color system calculated from the reflected light in the (n+1)-th measurement direction in the first measurement; bn represents the b* value in the Lab color system calculated from the reflected light in the n-th measurement direction in the first measurement; and bn+1 represents the b* value in the Lab color system calculated from the reflected light in the (n+1)-th measurement direction in the first measurement. In the formula, n represents an integer from 1-6. )

Description

Optical film, and polarizing plate, surface plate, image display panel, and image display device using the optical film.

[0001] This disclosure relates to an optical film, and to a polarizing plate, a surface plate, an image display panel, and an image display device using the optical film.

[0002] Optical films may be installed on the surfaces of image display devices such as televisions, laptops, and desktop PC monitors to suppress reflections of lighting and backgrounds such as people, and to reduce surface glare.

[0003] As an optical film to suppress background reflections, anti-glare films with an uneven surface have been proposed. However, anti-glare films have the problem that contrast tends to decrease due to the scattering of reflected light. As an optical film to suppress surface reflections, anti-reflective films with an anti-reflective layer on the surface have been proposed. However, anti-reflective films have the problem that they do not suppress background reflections well because their surface shape is smooth. As an optical film to suppress both background reflections and surface reflections, anti-glare anti-reflective films have been proposed in which an anti-reflective layer such as a low refractive index layer is laminated on an anti-glare layer (Patent Documents 1-3, etc.).

[0004] Japanese Patent Publication No. 2010-8757, Japanese Patent Publication No. 2019-28364, Japanese Patent Publication No. 2020-122926

[0005] The optical films described in Patent Documents 1 to 3 have an anti-reflective layer on top of an anti-glare layer, which can suppress reflections of the background and also suppress surface reflections. However, conventional image display devices using optical films like those described in Patent Documents 1 to 3, which have an anti-reflective layer laminated on top of an anti-glare layer, sometimes exhibited differences in color depending on the viewing angle, or displayed unexplained lines on the screen.

[0006] This disclosure aims to provide an optical film that can suppress variations in color depending on the viewing angle and the visibility of lines within the screen. Furthermore, this disclosure aims to provide a polarizing plate, a surface plate, an image display panel, and an image display device using the optical film.

[0007] The present disclosure provides the following <1> to <5>. <1> An optical film having a first surface and a second surface that is a surface opposite to the first surface, wherein the optical film has an antireflection layer and an antiglare layer in this order from the first surface toward the second surface, the first surface has an uneven shape, and the maximum value of six Δab calculated by the following Formula 1 is 0.20 or more and 2.50 or less. <<Formula 1>> Δab={(a ｎ＋１ , ＊ , ｎ , ＊ -a ｎ＋１ ) ２ +(b ｎ -b ｎ＋１ ) ２} １／２ (In Formula 1, a ｎ represents the a in the Lab color system calculated from the reflected light in the n-th measurement direction in the first measurement described below ＊ value, a ｎ＋１ represents the a in the Lab color system calculated from the reflected light in the (n+1)-th measurement direction in the first measurement described below ＊ value, b ｎ represents the b in the Lab color system calculated from the reflected light in the n-th measurement direction in the first measurement described below ＊ value, b ｎ＋１ represents the b in the Lab color system calculated from the reflected light in the (n+1)-th measurement direction in the first measurement described below ＊ value. In Formula 1, n represents an integer of 1 to 6.) <<First Measurement>> A first sample is prepared by bonding a black plate to the surface on the second surface side of the optical film via an adhesive layer. One surface of the first sample is the first surface of the optical film. The normal direction of the first surface of the first sample is defined as 0 degrees. Using a variable-angle spectrophotometer, parallel light rays are irradiated from the direction of +45 degrees on the first surface side of the first sample, and the reflected light of the parallel light rays is measured in seven directions of -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees and -60 degrees, respectively. With -30 degrees as the first measurement direction and -60 degrees as the seventh measurement direction, L of the Lab color system is respectively obtained from the reflected light in the first to seventh measurement directions ＊ value, a ＊ value and b ＊Calculate the value. <2> A polarizing plate having a polarizer, a first transparent protective plate disposed on one side of the polarizer, and a second transparent protective plate disposed on the other side of the polarizer, wherein at least one of the first transparent protective plate and the second transparent protective plate is the optical film described in <1>, and the second surface of the optical film and the polarizer are arranged facing each other. <3> A surface plate for an image display device having a protective film laminated onto a resin plate or a glass plate, wherein the protective film is the optical film described in <1>, and the second surface of the optical film and the resin plate or the glass plate are arranged facing each other. <4> An image display panel having a display element and an optical film disposed on the light-emitting surface side of the display element, wherein the optical film includes the optical film described in <1>. <5> An image display device including the image display panel described in <4>.

[0008] The optical film, polarizing plate, surface plate, image display panel, and image display device of this disclosure can easily suppress differences in color tone depending on the viewing angle, and the visibility of lines within the screen.

[0009] This is a schematic cross-sectional view showing one embodiment of the optical film of the present disclosure. This is a cross-sectional view showing one embodiment of the image display panel of the present disclosure. This is a diagram illustrating a method for measuring Δab of formula 1. This is a diagram illustrating a method for measuring ΔEab of formula 2.

[0010] Embodiments of this disclosure are described below. In this specification, the Lab color system refers to the one standardized by the International Commission on Illumination (CIE) in 1976. In this specification, the numerical range notation "AA to BB" means "AA or greater and BB or less". In this specification, multiple candidate upper limits and multiple candidate lower limits for a numerical range may be described. In this description, the numerical range may be constructed by combining any one candidate upper limit and any one candidate lower limit. As a first example, consider the description "Parameter B may be A1 or greater, A2 or greater, A3 or greater. Parameter B may be A4 or less, A5 or less, and A6 or less." In the first example, the numerical range of parameter B may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, and A3 or greater and A6 or less. In the second example, we will consider the statement, "Parameter C may be A1 or greater and A4 or less, A2 or greater and A5 or less, and A3 or greater and A6 or less." In the second example, the numerical range of parameter C may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, and A3 or greater and A6 or less.

[0011] [Optical Film] The optical film of this disclosure is as follows: An optical film having a first surface and a second surface which is opposite to the first surface, wherein the optical film has an anti-reflective layer and an anti-glare layer in that order from the first surface to the second surface, the first surface has an uneven shape, and the maximum value of the six Δab calculated by the following formula 1 is 0.20 or more and 2.50 or less. [Formula 1] Δab = {(a ｎ -a ｎ＋１ ) ２ + (b ｎ -b ｎ＋１ ) ２}１／２ (In Equation 1, a ｎ This is the a of the Lab color system calculated from the reflected light in the nth measurement direction in the first measurement described below. ＊ The value is shown, a ｎ＋１ This is the a of the Lab color system calculated from the reflected light in the (n+1)th measurement direction in the first measurement described below. ＊ The value is shown, b ｎ This is the b of the Lab color system calculated from the reflected light in the nth measurement direction in the first measurement described below. ＊ The value is shown, b ｎ＋１ This is the b of the Lab color system calculated from the reflected light in the (n+1)th measurement direction in the first measurement described below. ＊ The value is shown. In Equation 1, n is an integer between 1 and 6.) <First Measurement> A first sample is prepared by bonding a black plate to the second surface side of the optical film via an adhesive layer. One side of the first sample is the first surface of the optical film. The normal direction of the first surface of the first sample is set to 0 degrees. Using a bending-angle spectrophotometer, parallel light rays are shone from the +45 degree direction on the first surface side of the first sample, and the reflected light of the parallel light rays is measured in seven directions: -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, and -60 degrees. With -30 degrees as the first measurement direction and -60 degrees as the seventh measurement direction, the L of the Lab color system is measured from the reflected light of the first to seventh measurement directions. ＊ Value, a ＊ Value and b ＊ Calculate the value.

[0012] Figure 1 is a schematic cross-sectional view of the cross-sectional shape of the optical film 100 of this disclosure. The optical film 100 in Figure 1 has a first surface with an uneven shape and a second surface which is the surface opposite to the first surface. In Figure 1, the upper surface is the first surface S1 and the lower surface is the second surface S2. The optical film in Figure 1 has an anti-reflective layer 30, an anti-glare layer 20, and a substrate 10 in this order from the first surface to the second surface. Figure 1 is a schematic cross-sectional view. That is, the scale of each layer constituting the optical film 100 and the scale of the uneven shape are schematic for ease of illustration and differ from the actual scale. The same applies to Figures 2 and 3.

[0013] The optical film of this disclosure is not limited to the laminated configuration shown in Figure 1. For example, the optical film of this disclosure may have a laminated configuration without a substrate. Alternatively, the optical film of this disclosure may have layers other than the substrate, anti-glare layer, and anti-reflective layer.

[0014] <First Surface> The optical film of the present disclosure has a first surface. Preferably, the surface of the anti-reflective layer of the optical film of the present disclosure is the first surface.

[0015] The first surface of the optical film has an uneven surface. If the first surface does not have an uneven surface, the anti-glare properties of the optical film cannot be improved.

[0016] The first surface of the optical film must have a maximum value of 0.20 or more and 2.50 or less for the six Δab values ​​calculated by the following formula 1. [Formula 1] Δab = {(a ｎ -a ｎ＋１ ) ２ + (b ｎ -b ｎ＋１ ) ２} １／２ (In Equation 1, a ｎ This is the a of the Lab color system calculated from the reflected light in the nth measurement direction in the first measurement described below. ＊ The value is shown, a ｎ＋１ This is the a of the Lab color system calculated from the reflected light in the (n+1)th measurement direction in the first measurement described below. ＊ The value is shown, b ｎ This is the b of the Lab color system calculated from the reflected light in the nth measurement direction in the first measurement described below. ＊ The value is shown, b ｎ＋１ This is the b of the Lab color system calculated from the reflected light in the (n+1)th measurement direction in the first measurement described below. ＊The value is shown. In Equation 1, n is an integer between 1 and 6.) <First Measurement> A first sample is prepared by bonding a black plate to the second surface side of the optical film via an adhesive layer. One side of the first sample is the first surface of the optical film. The normal direction of the first surface of the first sample is set to 0 degrees. Using a bending-angle spectrophotometer, parallel light rays are shone from the +45 degree direction on the first surface side of the first sample, and the reflected light of the parallel light rays is measured in seven directions: -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, and -60 degrees. With -30 degrees as the first measurement direction and -60 degrees as the seventh measurement direction, the L of the Lab color system is measured from the reflected light of the first to seventh measurement directions. ＊ Value, a ＊ Value and b ＊ Calculate the value.

[0017] Δab in Equation 1 is calculated by following the steps A1 to A3 below. A1: A first sample 400 is prepared by bonding a black plate 300 to the second surface of an optical film 100 via an adhesive layer 200 (see Figure 3).

[0018] One side of the first sample 400 prepared as described above is the first surface S1 of the optical film. In Figure 3, the side of the first sample 400 opposite to the black plate side is the first surface S1 (Note: In Figure 3, the uneven shape of the first surface S1 is omitted for ease of illustration).

[0019] The difference between the refractive index of the adhesive layer of the first sample and the refractive index of the layer on the second surface side of the optical film shall be 0.05 or less. Preferably, the difference shall be 0.03 or less, and more preferably 0.01 or less. The difference between the refractive index of the adhesive layer of the first sample and the refractive index of the binder resin of the black board shall be 0.05 or less. Preferably, the difference shall be 0.03 or less, and more preferably 0.01 or less. The total light transmittance of the black board according to JIS K7361-1:1997 shall be 1.0% or less. Preferably, the total light transmittance of the black board shall be 0.5% or less, and more preferably 0.2% or less.

[0020] A2: The normal direction of the first surface S1 of the first sample 400 prepared in A1 above is set to 0 degrees. Using a bending-angle spectrophotometer, parallel light rays are shone onto the first sample from a direction of +45 degrees on the first surface side, and the reflected light of the parallel light rays is measured in seven directions: -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, and -60 degrees. With -30 degrees as the first measurement direction and -60 degrees as the seventh measurement direction, the L of the Lab color system is measured from the reflected light of the first to seventh measurement directions. ＊ Value, a ＊ Value and b ＊ Calculate the value.

[0021] The variable-angle spectrophotometer used in A2 above is a spectrophotometer in which the light source is fixed and the light receiver is movable. The variable-angle spectrophotometer 500 in Figure 3 has a light source 501 and a light receiver 502. In A2 above, the irradiation angle of the parallel light ray is set to +45 degrees, and the reflected light of the parallel light ray is measured in seven directions: -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, and -60 degrees. The solid line in Figure 3 shows the direction inclined at +45 degrees from the normal direction of the first surface S1 of the sample 400, and the dashed line in Figure 3 shows the direction inclined at -θ from the normal direction of the first surface S1 of the sample 400. In A2 above, in the seven measurement directions of -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, and -60 degrees, L ＊ Value, a ＊ Value and b ＊ The value is calculated. In A2 above, reflected light is measured with an aperture angle of 10 degrees. In the case of Figure 3, the aperture angle of the light receiver should be set to 10 degrees. Because the aperture angle is 10 degrees, for example, the measurement range for -30 degrees is -35 degrees to -25 degrees, the measurement range for -35 degrees is -40 degrees to -30 degrees, and the measurement range for -60 degrees is -65 degrees to -55 degrees. In A2 above, the field of view for spectral sensitivity is set to a 2-degree field of view. The International Commission on Illumination defines different color matching functions depending on the value of the field of view for spectral sensitivity. The color matching function is a function that approximates human perception. That is, the field of view for spectral sensitivity is L, which is set to approximate human perception from the measured value. ＊ Value, a ＊ Value and b ＊These are the conditions for calculating the value. Note that the 2-degree field of view is the human perception when observing a sample with a diameter of 1.7 cm from a distance of 50 cm. In A2 above and A3 described later, the interval between measurement wavelengths is 5 nm.

[0022] In this specification, the light source for the variable-angle spectrophotometer shall be the standard light source D65.

[0023] A3: a calculated in A2 above ＊ Value and b ＊ Based on the values, calculate Δab in Equation 1. In A2 above, -30 degrees is the first measurement direction and -60 degrees is the seventh measurement direction, and measurements are performed from the first to the seventh, so there are six adjacent measurement points. Therefore, the a calculated in A2 above ＊ Value and b ＊ Based on the values, six Δab values ​​are calculated. Then, the maximum value of these six Δab values ​​is extracted.

[0024] The optical film of this disclosure is required to have a maximum value of Δab of 2.50 or less. If the maximum value of Δab exceeds 2.50, the color will vary greatly depending on the viewing angle. The maximum value of Δab is preferably 2.00 or less, more preferably 1.56 or less, more preferably 1.50 or less, and even more preferably 1.00 or less.

[0025] The optical film of this disclosure is required to have a maximum value of Δab of 0.20 or more. Conventional image display devices using optical films in which an anti-reflective layer is laminated on an anti-glare layer sometimes had lines of unknown origin visible on the screen. The inventors have found that lines on the screen are visible for the following reasons (1) to (3): (1) An image display device using a micro-LED display element has a configuration in which multiple small panels of about 10 cm x 10 cm in size are arranged without gaps. If there is a slight difference in quality between each panel, the seams between the panels may be visible as lines. (2) If the components constituting the image display device, such as an optical film, are deformed or scratched, the deformed areas and scratched areas may be visible as lines. (3) When multiple optical films are joined together, the boundary lines between adjacent optical films may be visible as lines.

[0026] Defects present in uneven color tones tend to be less noticeable than defects present in uniform color tones. The inventors have found that by deliberately setting the maximum value of Δab to 0.20 or higher, without making it too small, a slight unevenness in color can be introduced, making the aforementioned lines less visible. In order to make the aforementioned lines less visible, it is desirable to increase the maximum value of Δab and increase the haze of the optical film. The maximum value of Δab is preferably 0.25 or higher, more preferably 0.30 or higher, and even more preferably 0.35 or higher.

[0027] Embodiments of the maximum value range of Δab include 0.20 to 2.50, 0.20 to 2.00, 0.20 to 1.50, 0.20 to 1.00, 0.25 to 2.50, 0.25 to 2.00, 0.25 to 1.50, 0.25 to 1.00, 0.30 to 2.50, 0.30 to 2.00, 0.30 to 1.50, 0.30 to 1.00, 0.35 to 2.50, 0.35 to 2.00, 0.35 to 1.50, and 0.35 to 1.00.

[0028] Δab can be adjusted, for example, by the roughness of the uneven surface of the first surface. Δab tends to increase as the proportion of flat areas on the first surface increases. Flat areas tend to have a thicker anti-reflective layer. Therefore, a higher proportion of flat areas makes the optical distance of the anti-reflective layer more susceptible to fluctuations with the angle of incidence, leading to a tendency for Δab to increase. For this reason, setting the average roughness above a predetermined value makes it easier to prevent Δab from becoming too large. On the other hand, if the average roughness of the first surface is above a predetermined value, and the proportion of flat areas on the first surface is excessively low, the optical distance of the anti-reflective layer becomes less susceptible to fluctuations with the angle of incidence. When the average roughness is the same, a smaller randomness in the roughness tends to result in a lower proportion of flat areas. For this reason, setting the randomness of the roughness above a predetermined value makes it easier to prevent Δab from becoming too small. Therefore, by setting the average roughness of the first surface above a predetermined value, and setting the randomness of the roughness of the first surface above a predetermined value, it is easier to set the maximum value of Δab to between 0.20 and 2.50. The average roughness of the first surface can be described as the Height mean and Slope mean, as described later. The randomness of the roughness of the first surface can be described as the Height coefficient of variation and Slope coefficient of variation, as described later. ΔEab, a ＊ MAX and a ＊ The absolute value of the difference from MIN, b ＊ MAX and b ＊ The absolute value of the difference from MIN shows a similar trend.

[0029] The following B1 to B2 are examples of means to make the average roughness of the first surface greater than or equal to a predetermined value, and the randomness of the roughness of the first surface greater than or equal to a predetermined value. B1: An anti-glare layer is formed as an anti-glare layer, having an average roughness greater than or equal to a predetermined value and a randomness of roughness greater than or equal to a predetermined value. B2: An anti-reflective layer is formed on the anti-glare layer so that the surface shape of the anti-glare layer formed in B1 is easily reflected in the surface shape of the first surface.

[0030] The optical film of this disclosure preferably has a minimum value of Δab in the following formula 1 of 0.02 or more and 0.50 or less. More preferably, the minimum value of Δab is 0.05 or more and 0.40 or less, and even more preferably 0.10 or more and 0.30 or less.

[0031] By setting the minimum value of Δab to 0.02 or higher, it becomes easier to suppress the visibility of lines within the image display device screen. By setting the minimum value of Δab to 0.50 or lower, it becomes easier to suppress changes in color tone depending on the viewing angle.

[0032] The optical film of this disclosure, in the first measurement, is calculated from the reflected light in the first to seventh measurement directions, respectively, using the Lab color system a ＊ The maximum value of a ＊ MAX and a ＊ a is the minimum value of the value. ＊ The absolute value of the difference from MIN is preferably 0.25 or more and 3.00 or less. The absolute value of the difference is more preferably 0.35 or more and 2.00 or less, and even more preferably 0.45 or more and 1.00 or less. By setting the absolute value of the difference to 0.25 or more, it becomes easier to suppress the visibility of lines within the screen of the image display device. By setting the absolute value of the difference to 3.00 or less, it becomes easier to suppress changes in color tone depending on the viewing angle.

[0033] a ＊ The maximum value is preferably 0.40 or more and 3.00 or less, and more preferably 0.50 or more and 2.00 or less. ＊ MIN is preferably -0.10 or more and 0.50 or less, and more preferably 0.01 or more and 0.30 or less.

[0034] The optical film of this disclosure, in the first measurement, is calculated from the reflected light in the first to seventh measurement directions, respectively, using the b color system of the Lab color system. ＊ The maximum value is b ＊ MAX and b ＊ The minimum value of b ＊The absolute value of the difference from MIN is preferably 0.30 or more and 3.50 or less. The absolute value of the difference is more preferably 0.40 or more and 2.50 or less, and even more preferably 0.50 or more and 2.00 or less. By setting the absolute value of the difference to 0.30 or more, it becomes easier to suppress the visibility of lines on the screen of the image display device. By setting the absolute value of the difference to 3.50 or less, it becomes easier to suppress changes in color tone depending on the viewing angle.

[0035] b ＊ MAX is preferably 0.00 or more and 3.50 or less, and more preferably 0.50 or more and 2.50 or less. ＊ MIN is preferably -1.50 or more and 0.50 or less, and more preferably 0.10 or more and 0.30 or less.

[0036] The optical film of this disclosure, in the first measurement, calculates the L of the Lab color system from the reflected light in the first to seventh measurement directions. ＊ The maximum value is L ＊ Preferably, the product of MAX and the haze of the optical film according to JIS K7136:2000 is 850 or less, and more preferably 400 or less.

[0037] When the anti-glare properties of the optical film are increased, the screen tends to appear whiter. By setting the product to 850 or less, it is possible to suppress the screen appearing whiter even when the anti-glare properties of the optical film are increased. The product is more preferably 400 or less, and even more preferably 200 or less. If the product is too small, the anti-glare properties tend to decrease. For this reason, the product is preferably 5 or more, more preferably 50 or more, and even more preferably 100 or more.

[0038] The optical film of the present disclosure preferably has ΔEab of the following Formula 2 of 4.80 or more and 20.00 or less. ΔEab is preferably 7.00 or more and 17.50 or less, more preferably 8.50 or more and 16.00 or less, and even more preferably 10.00 or more and 12.00 or less. By setting ΔEab to 4.80 or more, it is possible to more easily suppress the visibility of lines on the screen of an image display device. In particular, for an optical film having a large ΔL, setting ΔEab to 4.80 or more makes it easy to suppress the visibility of lines on the screen. By setting ΔEab to 20.00 or less, it is possible to more easily suppress the change in hue depending on the viewing angle.

[0039] <<Formula 2>> ΔEab = {(L ５ -L ６０ ) ２ +(a ５ -a ６０ ) ２ +(b ５ -b ６０ ) ２} １／２ (However, in Formula 2, L ５ , a ５ , b ５ , L ６０ , a ６０ and b ６０ mean the values obtained in the second measurement described below.) <<Second Measurement>> The normal direction of the first surface of the first sample is defined as 0 degrees. Using a variable-angle spectrophotometer, parallel light rays are irradiated from the direction of +5 degrees on the first surface side of the first sample, and the reflected light of the parallel light rays is measured in the direction of -5 degrees. The L of the Lab color system calculated from the measured reflected light at -5 degrees ＊ value, a ＊ value and b ＊ value are respectively defined as L ５ , a ５ , b ５ . Using the variable-angle spectrophotometer, parallel light rays are irradiated from the direction of +60 degrees on the first surface side of the first sample, and the reflected light of the parallel light rays is measured in the direction of -60 degrees. The L of the Lab color system calculated from the measured reflected light at -60 degrees ＊ value, a ＊ value and b ＊ value are respectively defined as L ６０a ６０ and b ６０ Let's assume that.

[0040] ΔEab in Equation 1 is calculated using the following procedure A'1 to A'4. A'1: Prepare a second sample for measurement. The second sample for measurement is the same as the first sample used in the first measurement.

[0041] A'2: The normal direction of the first surface S1 of the first sample 400 is set to 0 degrees. Using a bending spectrophotometer, parallel light rays are shone onto the first surface S1 side of sample 400 from a direction of +5 degrees, and the reflected light of the parallel light rays is measured at a direction of -5 degrees. The L of the Lab color system is calculated from the measured reflected light at -5 degrees. ＊ Value, a ＊ Value and b ＊ The values ​​are L ５ a ５ , b ５ Let's assume that.

[0042] The variable-angle spectrophotometer used in A'2 above is a spectrophotometer that can irradiate parallel light rays by varying the irradiation angle. The variable-angle spectrophotometer 500 in Figure 4 has a light source 501 and a light receiver 502. In A'2 above, the irradiation angle of the parallel light rays is set to +5 degrees, and the reflected light of the parallel light rays is measured in the direction of -5 degrees. The solid line in Figure 4 shows the direction tilted by +θ from the normal direction of the first surface S1 of the sample 400, and the dashed line in Figure 4 shows the direction tilted by -θ from the normal direction of the first surface S1 of the sample 400. In A'2 above, the reflected light is measured with an aperture angle of 10 degrees. In the case of Figure 4, the aperture angle of the light receiver should be set to 10 degrees. In A'2 above and A'3 below, the field of view of the spectral sensitivity is set to a 2-degree field of view. In A'2 above and A'3 below, the interval of the measurement wavelengths is set to 5 nm.

[0043] In this specification, the light source for the variable-angle spectrophotometer shall be the standard light source D65.

[0044] A'3: Using a bending-angle spectrophotometer, parallel light rays are shone onto the first surface S1 side of sample 400 from a direction of +60 degrees, and the reflected light of the parallel rays is measured in the direction of -60 degrees. The L of the Lab color system is calculated from the measured reflected light at -60 degrees. ＊ Value, a ＊ Value and b ＊The values ​​are L ６０ a ６０ and b ６０ Let's assume that.

[0045] The same variable angle spectrophotometer used in A'3 above is used in A'2 above. The center of the position where the parallel light rays irradiate the first sample in A'2 above and the center of the position where the parallel light rays irradiate the first sample in A'3 above are made to be the same. The said sameness includes substantially the same. With a general-purpose variable angle spectrophotometer, the irradiation angle can be varied while keeping the center of the position where the parallel light rays irradiate the sample substantially the same. In A'3 above, the irradiation angle of the parallel light rays is set to +60 degrees, and the reflected light of the parallel light rays is measured in the direction of -60 degrees. In A'3 above, the reflected light is measured with an aperture angle of 10 degrees. In the case of Figure 4, the aperture angle of the light receiver should be set to 10 degrees.

[0046] A'4: L obtained in A'2 above ５ a ５ , b ５ and L obtained in A'3 above ６０ a ６０ and b ６０ Apply this to equation 2 above and calculate ΔEab.

[0047] In this specification, Δab, ΔEab, a ＊ MAX, a ＊ MIN, b ＊ MAX, b ＊Optical parameters such as MIN, haze, total light transmittance, 60-degree specular gloss, and reflectance; unless otherwise specified, these parameters refer to the average value of 14 measurements obtained by subtracting the maximum and minimum values ​​from 16 measurements. In this specification, the 16 measurement locations are determined by removing a 1 cm margin from the outer edge of the measurement sample, and then drawing lines that divide the remaining area into five equal parts vertically and horizontally. The 16 intersection points are used as the measurement centers. For example, if the measurement sample is rectangular, a 0.5 cm margin is removed from the outer edge of the rectangle, and measurements are taken at 16 intersection points of lines that divide the remaining area into five equal parts vertically and horizontally. The average value of the 14 measurements obtained by subtracting the maximum and minimum values ​​from the 16 measurements is then used as the parameter value. If the measurement sample is a shape other than a rectangle, such as a circle, ellipse, triangle, or pentagon, a rectangle is drawn inscribed within this shape, and 16 measurements are taken with respect to the rectangle using the method described above.

[0048] In this specification, Δab, ΔEab, a ＊ MAX, a ＊ MIN, b ＊ MAX, b ＊ Optical parameters such as MIN, haze, total light transmittance, and reflectance; roughness parameters such as height mean and height coefficient of variation; and other parameters shall be measured at a temperature of 23°C and a relative humidity of 40% to 65%, unless otherwise specified. Furthermore, before starting each measurement, the target sample shall be exposed to the aforementioned atmosphere for 30 minutes before measurement.

[0049] In this specification, the average of roughness parameters such as the height average and slope average shall be calculated by the following procedures g1 to g3. g1: Height data is acquired for a 218 μm × 218 μm area on the first surface of the measurement sample. The interval for acquiring height data within the area shall be 0.22 μm. Based on the obtained height data, the height average and slope average within the 218 μm × 218 μm area are calculated. This provides the height average and slope average for one measurement location. g2: The measurement in g1 above is performed at the 16 measurement locations of the measurement sample to obtain the height average and slope average for 16 locations. g3: The average of 14 measurements obtained by subtracting the maximum and minimum values ​​from the height average and slope average for 16 locations shall be the height average and slope average of this disclosure.

[0050] In this specification, the coefficients of variation of roughness parameters such as the Height coefficient of variation and the Slope coefficient of variation shall be calculated by the following procedures h1 to h3. h1: Height data is acquired for a 218 μm × 218 μm area on the first surface of the measurement sample. The interval for acquiring height data within the area shall be 0.22 μm. Based on the obtained height data, the Height coefficient of variation and the Slope coefficient of variation are calculated for the 218 μm × 218 μm area. This provides the Height coefficient of variation and the Slope coefficient of variation for one measurement location. h2: The Height coefficient of variation and the Slope coefficient of variation for 16 locations are obtained by performing the measurement in h1 above at the 16 measurement locations of the measurement sample. h3: The average of 14 measurements obtained by subtracting the maximum and minimum values ​​from the 16 Height coefficients of variation and Slope coefficients of variation is defined as the Height coefficient and Slope coefficient of variation in this disclosure.

[0051] The optical film of this disclosure preferably exhibits predetermined values ​​for roughness parameters such as the height average, height coefficient of variation, slope average, and slope coefficient of variation of the first surface.

[0052] In this specification, the roughness parameter of the first surface is measured using an interference microscope. In this specification, the measurement conditions for the interference microscope are a measurement area of ​​218 μm × 218 μm and a resolution of 0.22 μm. Resolution refers to the interval between adjacent measurement points. That is, in the interference microscope measurement described herein, height data is acquired at intervals of 0.22 μm within a 218 μm × 218 μm area.

[0053] As described above, the average height is calculated using the procedures g1 to g3 above, and the coefficient of variation of height is calculated using the procedures h1 to h3 above. Here, the "average height of one measurement point" in g1 and the "coefficient of variation of height of one measurement point" in h1 above are calculated as follows: j1: At one measurement point, height data is obtained at 0.22 μm intervals within a 218 μm × 218 μm area. The surface consisting of the average values ​​of the obtained height data is defined as the "reference plane". j2: One independent area with a height higher than the reference plane is defined as one peak area. The maximum height within one peak area is defined as Hmax. j3: Hmax is calculated for each of the multiple peak areas included in the 218 μm × 218 μm area. The average of the Hmax of the multiple peak areas is defined as the average height of one measurement point (unit: μm). Furthermore, the coefficient of variation calculated from the Hmax values ​​of multiple peak regions is used as the Height coefficient of variation for a single measurement point. (Note: The coefficient of variation is a dimensionless parameter that has no units, as it is calculated by dividing the standard deviation σ by the mean value.)

[0054] As described above, the Slope average is calculated using the procedures g1 to g3 above, and the Slope coefficient of variation is calculated using the procedures h1 to h3 above. Here, the "Slope average of one measurement point" in g1 and the "Slope coefficient of variation of one measurement point" in h1 above are calculated as follows: k1: At one measurement point, height data is obtained at 0.22 μm intervals within a 218 μm × 218 μm area. The plane consisting of the average values ​​of the obtained height data is defined as the "reference plane". k2: One independent area with a height higher than the reference plane is defined as one peak region. Within one peak region, the Slope between adjacent measurement points is calculated based on the height data at 0.22 μm intervals. The Slope is calculated by dividing the length in the height direction [μm] by the length in the plane direction [mm] (unit: "μm / mm"). k3: Slopes are calculated for each of the multiple peak regions contained within a 218 μm × 218 μm area. The average of the slopes from these multiple peak regions is taken as the average slope for one measurement point (unit: μm / mm). Furthermore, the coefficient of variation calculated from the slopes from these multiple peak regions is taken as the coefficient of variation of the slope for one measurement point. (Note: The coefficient of variation is a dimensionless parameter calculated by dividing the standard deviation σ by the mean.)

[0055] The average height of the first surface is preferably 0.03 μm or more, more preferably 0.15 μm or more, and even more preferably 0.20 μm or more. Furthermore, the coefficient of variation of the height of the first surface is preferably 0.50 or more, more preferably 1.00 or more, and even more preferably 1.50 or more. By setting the average height of the first surface to 0.03 μm or more, it is easier to improve the anti-glare properties. Also, by setting the average height of the first surface to 0.03 μm or more and the coefficient of variation of the height of the first surface to 0.50 or more, it is easier to set Δab to 0.20 or more and 2.50 or less. The average height of the first surface is preferably 0.40 μm or less, more preferably 0.35 μm or less, and even more preferably 0.30 μm or less. By setting the average height of the first surface to 0.40 μm or less, it is easier to suppress the screen from appearing whitish. The coefficient of variation of the height of the first surface is preferably 3.00 or less, more preferably 2.50 or less, and even more preferably 2.00 or less. By setting the coefficient of variation of the height of the first surface to 3.00 or less, it is easier to suppress the screen from appearing whitish.

[0056] The average Slope of the first surface is preferably 25.0 μm / mm or more, more preferably 50.0 μm / mm or more, and even more preferably 100.0 μm / mm or more. Furthermore, the coefficient of variation of the Slope of the first surface is preferably 0.30 or more, more preferably 0.34 or more, and even more preferably 0.37 or more. By setting the average Slope of the first surface to 25.0 μm / mm or more, it is easier to improve the anti-glare properties. Also, by setting the average Slope of the first surface to 25.0 μm / mm or more and the coefficient of variation of the Slope of the first surface to 0.30 or more, it is easier to set Δab to 0.20 or more and 2.50 or less. The average Slope of the first surface is preferably 400.0 μm / mm or less, more preferably 300.0 μm / mm or less, and even more preferably 200.0 μm / mm or less. By setting the average Slope of the first surface to 400.0 μm / mm or less, it is easier to suppress the screen from appearing whitish. The coefficient of variation of the Slope of the first surface is preferably 1.00 or less, more preferably 0.80 or less, and even more preferably 0.60 or less. By setting the coefficient of variation of the Slope of the first surface to 1.00 or less, it is possible to reduce localized areas with extremely steep slopes and improve the texture.

[0057] <Laminated Structure> The optical film of this disclosure has an anti-reflective layer and an anti-glare layer in this order from the first surface to the second surface. Preferably, the outermost surface on the first surface side of the optical film is the anti-reflective layer. The optical film of this disclosure may have layers other than the anti-reflective layer and the anti-glare layer. Examples of layers other than the anti-reflective layer and the anti-glare layer include a substrate, an antistatic layer, an adhesive layer, etc. Preferably, the optical film of this disclosure has an anti-reflective layer, an anti-glare layer and a substrate in this order from the first surface to the second surface.

[0058] <Substrate> Optical films preferably have a substrate for ease of manufacturing and handling.

[0059] The substrate is preferably one that possesses light transmittance, smoothness, and heat resistance, and also has excellent mechanical strength. Examples of such substrates include plastic films such as polyester, triacetylcellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyetherketone, polymethyl methacrylate, polycarbonate, polyurethane, and amorphous olefin (Cyclo-Olefin-Polymer: COP). The substrate may be made by laminating two or more plastic films. Among plastic films, stretched polyester films are preferred for their mechanical strength and dimensional stability, and biaxially stretched polyester films are more preferred. Examples of polyester films include polyethylene terephthalate film and polyethylene naphthalate film. TAC film and acrylic film are preferred because they easily provide good light transmittance and optical isotropy. COP film and polyester film are preferred because they have excellent weather resistance.

[0060] The thickness of the substrate is preferably 5 μm to 300 μm, more preferably 20 μm to 200 μm, and even more preferably 30 μm to 120 μm. When thinning an optical film, the preferred upper limit of the substrate thickness is 100 μm or less, and the more preferred upper limit is 80 μm or less. Furthermore, when the substrate is a low-moisture permeability substrate such as polyester, COP, or acrylic, the preferred upper limit of the substrate thickness for thinning is 60 μm or less, and the more preferred upper limit is 40 μm or less. Even in the case of large screens, if the upper limit of the substrate thickness is within the above range, it is also preferable because distortion can be made less likely to occur. The thickness of the substrate is measured with a general-purpose film thickness measuring instrument. The thickness of the substrate refers to the average value measured at any 10 points.

[0061] The substrate preferably has a total light transmittance of 70% or more, more preferably 80% or more, and even more preferably 85% or more, according to JIS K7361-1:1997. The substrate preferably has a haze of 10% or less, more preferably 5% or less, and even more preferably 3% or less, according to JIS K7136:2000.

[0062] The surface of the substrate may be subjected to physical treatments such as corona discharge treatment or chemical treatments to improve adhesion. Furthermore, the substrate may have an easily adhesive layer on its surface.

[0063] 《Anti-glare layer》 The anti-glare layer is the core layer responsible for anti-glare properties. The anti-glare layer can be formed by, for example, (A) a method using an embossing roll, (B) etching, (C) molding with a mold, or (D) coating by application. Molding with a mold (C) is preferable for obtaining a stable surface shape, while coating by application (D) is preferable for productivity and handling of multiple product types.

[0064] In method (C), for example, an anti-glare layer can be formed by pouring resin into a mold and removing the molded resin from the mold. The molded resin removed from the mold may be placed on a substrate. The mold used is one in which the surface shape of the anti-glare layer is inverted. Such a mold can be made, for example, by the methods of (c1-1) to (c1-2) or (c2) below. (c1-1) A shape is created by simulation in which roughness parameters such as height average and slope average are within a predetermined range. Furthermore, the simulated shape is inverted. (c1-2) A mold is obtained by engraving the surface of a metal with laser light or processing the surface of a metal by photolithography so that the inverted shape is reflected.

[0065] (c2) A mold is obtained by reversing the shape of the anti-glare layer made in (D) using a general-purpose electroforming method.

[0066] When forming an anti-glare layer by (D), for example, the following means (d1) and (d2) can be used. (d1) is preferred over (d2) in that it is easier to adjust the range of the surface shape. (d1) A means of forming an anti-glare layer having irregularities based on particles by applying and drying a coating liquid containing a binder component and particles. (d2) A means of forming irregularities by applying a coating liquid containing an arbitrary resin and a resin that is poorly compatible with the resin, and then separating the resins in phase.

[0067] -Thickness- The thickness T of the anti-glare layer is preferably 2.0 μm to 10.0 μm, more preferably 3.0 μm to 8.0 μm, and even more preferably 4.0 μm to 6.0 μm, in order to balance curl suppression, mechanical strength, hardness, and toughness. The thickness of the anti-glare layer is calculated by selecting 20 arbitrary points from cross-sectional photographs of the optical film taken with a scanning transmission electron microscope and using the average value. The acceleration voltage of the STEM is 10 kV to 30 kV, and the magnification of the STEM is 1000x to 7000x.

[0068] - Components - The anti-glare layer preferably contains a binder component and particles. The particles include organic particles and inorganic particles, with inorganic particles being preferred. In other words, the anti-glare layer preferably contains a binder component and inorganic particles. Furthermore, it is more preferable that the anti-glare layer contains a binder component, inorganic particles and organic particles. In addition, the anti-glare layer may optionally contain additives such as nanoparticles on the nanometer scale, refractive index adjusters, antistatic agents, leveling agents, ultraviolet absorbers, light stabilizers, antioxidants, viscosity modifiers and thermal polymerization initiators.

[0069] —Particles— Examples of inorganic particles include silica, alumina, zirconia, and titania, with silica being preferred. Among inorganic particles, amorphous inorganic particles are preferred, and amorphous silica is more preferred. Examples of organic particles include particles containing one or more resins selected from polymethyl methacrylate, polyacrylic-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone, fluororesin, and polyester resin.

[0070] Shapeless inorganic particles refer to inorganic particles that do not have a specific shape. Methods for producing shapeless inorganic particles include "a method of crushing large-particle inorganic particles and then classifying them as needed" and "a sedimentation method."

[0071] The particles preferably include inorganic particles. More preferably, the particles include amorphous inorganic particles, and even more preferably, amorphous inorganic particles and organic particles. Amorphous silica is preferred as the amorphous inorganic particles.

[0072] Inorganic particles such as amorphous inorganic particles preferably include two types of inorganic particles with different volume-based cumulative distributions d50 of particle size. Including two types of inorganic particles with different d50 makes it easier to impart randomness to the surface shape, thereby making it easier to increase the average height and average slope, as well as the coefficient of variation of height and the coefficient of variation of slope. To make it easier to increase the average height, average slope, coefficient of variation of height and coefficient of variation of slope, it is more preferable to include amorphous inorganic particles as the two types of inorganic particles with different d50. There may be two or more types of inorganic particles with different d50, or three or more types.

[0073] Among two types of inorganic particles with different d50s, the d50 of one inorganic particle is defined as D1, and the d50 of the other inorganic particle is defined as D2, and D1 < D2. In this case, D2-D1 is preferably 0.5 μm or more and 3.5 μm or less, more preferably 0.7 μm or more and 3.0 μm or less, and even more preferably 0.9 μm or more and 2.5 μm or less. By setting D2-D1 to 0.5 μm or more, it is possible to easily increase the height mean and slope mean, and also to easily increase the height coefficient of variation and slope coefficient of variation. By setting D2-D1 to 3.5 μm or less, it is possible to easily suppress the height mean, slope mean, height coefficient of variation and slope coefficient of variation from becoming too large.

[0074] Inorganic particles such as amorphous inorganic particles preferably have a volume-based cumulative distribution d50 of particle size of 2.0 μm or more and 6.0 μm or less, more preferably 2.3 μm or more and 5.5 μm or less, and even more preferably 2.5 μm or more and 5.3 μm or less. If the inorganic particles include two or more types of inorganic particles with different d50s, it is preferable that the d50 of all inorganic particles is within the above range.

[0075] The ratio of the thickness T of the anti-glare layer to the d50 of inorganic particles such as amorphous inorganic particles is preferably such that d50 / T is 0.35 or more and 1.00 or less, more preferably 0.40 or more and 0.90 or less, and even more preferably 0.45 or more and 0.87 or less. Setting d50 / T to 0.35 or more makes it easier to impart anti-glare properties to the anti-glare layer, and setting d50 / T to 1.00 or less makes it easier to suppress the shedding of inorganic particles from the anti-glare layer.

[0076] The content of inorganic particles, such as amorphous inorganic particles, is preferably 3 parts by mass or more and 30 parts by mass or less, more preferably 4 parts by mass or more and 25 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of binder resin. By setting the content of inorganic particles, such as amorphous inorganic particles, to 3 parts by mass or more, it is possible to easily impart anti-glare properties to the anti-glare layer. By setting the content of inorganic particles, such as amorphous inorganic particles, to 30 parts by mass or less, it is possible to suppress the Height coefficient of variation and the Slope coefficient of variation from becoming too small. In particular, when d50 contains a large amount of one type of inorganic particle, uniform irregularities are easily formed, so the Height coefficient of variation and the Slope coefficient of variation tend to become small.

[0077] Among two types of inorganic particles with different d50 values, the content of inorganic particles with a smaller d50 is defined as M1, and the content of inorganic particles with a larger d50 is defined as M2. In this case, M1 / M2 is preferably 0.07 or more and 10.00 or less, more preferably 0.10 or more and 6.00 or less, and even more preferably 0.12 or more and 4.00 or less. By setting M1 / M2 within the above range, it becomes easier to set the Height coefficient of variation and the Slope coefficient of variation within the above range.

[0078] The anti-glare layer may contain organic particles. Including organic particles makes it easier to suppress the aggregation of inorganic particles. Also, organic particles have a relatively uniform particle size. Therefore, by including organic particles in addition to inorganic particles, it is easier to adjust the coefficient of variation of the roughness parameter to a desired range. For example, when the inorganic particle content is fixed and the organic particle content is varied, the coefficient of variation of the roughness parameter tends to decrease as the organic particle content increases. The organic particle content is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 3 to 12 parts by mass per 100 parts by mass of binder resin. By including 1 part by mass or more of organic particles, it is easier to impart anti-glare properties to the anti-glare layer. By including 20 parts by mass or less of organic particles, it is easier to suppress the shedding of organic particles from the anti-glare layer.

[0079] The average particle diameter of the organic particles is preferably 1.0 μm or more and 5.0 μm or less, more preferably 1.2 μm or more and 3.0 μm or less, and even more preferably 1.3 μm or more and 2.5 μm or less. By setting the average particle diameter of the organic particles to 1.0 μm or more, it is easier to impart anti-glare properties to the anti-glare layer. By setting the average particle diameter of the organic particles to 5.0 μm or less, it is easier to suppress the shedding of organic particles from the anti-glare layer. In this specification, the average particle diameter of the organic particles refers to the value obtained as the volume average value d50 in the laser diffraction method.

[0080] Examples of organic particle shapes include spherical, disc-shaped, rugby ball-shaped, and irregular shapes. Among these shapes, spherical organic particles are preferred. By using spherical organic particles, it is easier to suppress defects caused by organic particles flying out of the coating film, and the occurrence of areas where the physical properties of the coating film differ locally.

[0081] The average particle diameter of organic particles relative to the thickness of the anti-glare layer (average particle diameter of organic particles / thickness of the anti-glare layer) is preferably 0.20 or more and 0.70 or less, more preferably 0.23 or more and 0.50 or less, and even more preferably 0.25 or more and 0.35 or less. Setting the average particle diameter of organic particles / thickness of the anti-glare layer to 0.20 or more makes it easier to impart anti-glare properties to the anti-glare layer. Setting the average particle diameter of organic particles / thickness of the anti-glare layer to 0.70 or less makes it easier to suppress the shedding of organic particles from the anti-glare layer.

[0082] —Inorganic Fine Particles— The anti-glare layer may further contain inorganic fine particles in addition to the binder resin and particles. In this specification, inorganic fine particles and the particles described above can be distinguished by their average particle size. By including inorganic fine particles in the anti-glare layer, the difference between the refractive index of the particles and the refractive index of the composition other than the particles in the anti-glare layer becomes smaller, making it easier to reduce internal haze.

[0083] Examples of inorganic fine particles include those made of silica, alumina, zirconia, and titania. Among these, silica is preferred because it is easier to suppress the generation of internal haze.

[0084] The average particle size of the inorganic fine particles is preferably 1 nm to 200 nm, more preferably 2 nm to 100 nm, and even more preferably 5 nm to 50 nm.

[0085] The average particle diameter of inorganic microparticles is calculated by the following steps (E1) to (E3): (E1) Image the cross-section of the optical film with a TEM or STEM. The accelerating voltage of the TEM or STEM should be between 10kV and 30kV, and the magnification should be between 50,000x and 300,000x. (E2) Extract any 10 particles from the observed image and calculate the particle diameter of each individual particle. The particle diameter of each individual particle is defined as the distance between two parallel lines that maximizes the distance between the lines when the cross-section of the particle is enclosed by those two lines. (E3) Perform the same procedure five times on observation images of the same sample from different screens, and the average value obtained from the number average of the particle diameters of a total of 50 particles is taken as the average primary particle diameter of the particles.

[0086] —Binder Components— Examples of binder components include organic binder components and inorganic binder components such as silica-based matrices, with organic binder components being preferred. In other words, the binder component of the anti-glare layer of this disclosure is preferably an organic binder resin.

[0087] The binder resin preferably contains a cured product of a curable resin composition, such as a cured product of a thermosetting resin composition or a cured product of an ionizing radiation-curable resin composition, in order to improve scratch resistance, and more preferably contains a cured product of an ionizing radiation-curable resin composition. The binder resin may also contain a thermoplastic resin to the extent that it does not impair the effects of this disclosure.

[0088] The ratio of the cured product of the curable resin composition to the total amount of binder resin is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass, in order to easily improve scratch resistance.

[0089] A thermosetting resin composition is a composition containing at least a thermosetting resin, which hardens upon heating. Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea-melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. A curing agent is added to these curable resins as needed in the thermosetting resin composition.

[0090] Ionizing radiation-curable resin compositions are compositions containing compounds having ionizing radiation-curable functional groups (hereinafter also referred to as "ionizing radiation-curable compounds"). Examples of ionizing radiation-curable functional groups include ethylenically unsaturated bonding groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, as well as epoxy groups and oxetanyl groups. As ionizing radiation-curable compounds, compounds having ethylenically unsaturated bonding groups are preferred, compounds having two or more ethylenically unsaturated bonding groups are more preferred, and among these, polyfunctional (meth)acrylate compounds having two or more ethylenically unsaturated bonding groups are even more preferred. Both monomers and oligomers can be used as polyfunctional (meth)acrylate compounds. Ionizing radiation refers to electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or crosslinking molecules. Typically, ultraviolet (UV) or electron beams (EB) are used, but other electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams can also be used.

[0091] Among polyfunctional (meth)acrylate compounds, examples of difunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, and 1,6-hexanediol diacrylate. Examples of trifunctional or more (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid-modified tri(meth)acrylate. The above (meth)acrylate monomers may also have a modified molecular skeleton. For example, the above (meth)acrylate monomers can also be used in which part of the molecular skeleton has been modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, etc.

[0092] Examples of polyfunctional (meth)acrylate oligomers include acrylate polymers such as urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate. Urethane (meth)acrylate can be obtained, for example, by the reaction of a polyhydric alcohol and an organic diisocyanate with hydroxy (meth)acrylate. Preferred epoxy (meth)acrylates are (meth)acrylates obtained by reacting a trifunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. with (meth)acrylic acid, (meth)acrylates obtained by reacting a bifunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. with a polybasic acid and (meth)acrylic acid, and (meth)acrylates obtained by reacting a bifunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. with phenols and (meth)acrylic acid.

[0093] The weight-average molecular weight of the polyfunctional (meth)acrylate oligomer is preferably 500 to 3000, and more preferably 700 to 2500. In this specification, the weight-average molecular weight is the average molecular weight measured by GPC analysis and converted to standard polystyrene.

[0094] Furthermore, monofunctional (meth)acrylates may be used in combination as ionizing radiation-curable compounds for purposes such as adjusting the viscosity of the anti-glare coating solution. Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isobornyl (meth)acrylate. The above ionizing radiation-curable compounds can be used individually or in combination of two or more.

[0095] When the ionizing radiation-curable compound is an ultraviolet-curable compound, the ionizing radiation-curable composition preferably contains additives such as photopolymerization initiators and photopolymerization accelerators. Examples of photopolymerization initiators include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler ketone, benzoin, benzyldimethyl ketal, benzoylbenzoate, α-acyloxime esters, thioxanthones, etc. Photopolymerization accelerators can reduce polymerization inhibition by air during curing and accelerate the curing rate. Examples of accelerators include p-dimethylaminobenzoate isoamyl ester and p-dimethylaminobenzoate ethyl ester.

[0096] When the binder resin contains a cured product of an ionizing radiation-curable resin composition, the ionizing radiation-curable resin composition preferably contains a polyfunctional (meth)acrylate monomer and a polyfunctional (meth)acrylate oligomer. The mass ratio of the polyfunctional (meth)acrylate monomer to the polyfunctional (meth)acrylate oligomer (mass of polyfunctional (meth)acrylate monomer:mass of polyfunctional (meth)acrylate oligomer) is preferably 20:80 to 99:1, more preferably 40:60 to 95:5, and even more preferably 60:40 to 90:10. By including a predetermined proportion or more of the polyfunctional (meth)acrylate monomer, the scratch resistance of the anti-glare layer can be easily improved. By including a predetermined proportion or more of the polyfunctional (meth)acrylate oligomer, the viscosity of the coating liquid for the anti-glare layer can be increased, making it easier to suppress particles from settling below the anti-glare layer, and also making it easier to suppress the binder resin from flowing down between the protrusions based on the particles. Therefore, the randomness effect described above can be easily exerted by two types of inorganic particles with different d50 values. On the other hand, if the proportion of polyfunctional (meth)acrylate oligomers becomes too high, the strength of the anti-glare layer may decrease. Also, if the viscosity of the coating liquid for the anti-glare layer is too high, the randomness effect described above may become too strong, and the Height coefficient of variation and the Slope coefficient of variation may become too large. For this reason, it is preferable that the ionizing radiation-curable resin composition contains a predetermined amount of polyfunctional (meth)acrylate oligomer and a predetermined amount of polyfunctional (meth)acrylate monomer.

[0097] —Solvents and Drying Conditions—The coating liquid for the anti-glare layer preferably contains a solvent to adjust the viscosity or to dissolve or disperse each component. Since the surface shape of the anti-glare layer after coating and drying differs depending on the type of solvent, it is preferable to select a solvent considering the saturated vapor pressure of the solvent, the penetration of the solvent into the substrate, etc. Examples of solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers such as dioxane and tetrahydrofuran; aliphatic hydrocarbons such as hexane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated carbons such as dichloromethane and dichloroethane; esters such as methyl acetate, ethyl acetate, and butyl acetate; alcohols such as isopropanol, butanol, and cyclohexanol; cellosolves such as methyl cellosolve and ethyl cellosolve; glycol ethers such as propylene glycol monomethyl ether acetate; cellosolve acetates; sulfoxides such as dimethyl sulfoxide; and amides such as dimethylformamide and dimethylacetamide. The solvent may be used alone or as a mixture of two or more. The proportion of the solvent in the anti-glare coating solution is preferably 40% by mass or more and 85% by mass or less, more preferably 50% by mass or more and 80% by mass or less, and even more preferably 60% by mass or more and 75% by mass or less.

[0098] In the coating solution for the anti-glare layer, it is preferable to use a solvent with a fast evaporation rate and a solvent with a slow evaporation rate as described below. In this specification, a solvent with a fast evaporation rate means a solvent with an evaporation rate of 100 or more when the evaporation rate of butyl acetate is set to 100, and a solvent with a slow evaporation rate means a solvent with an evaporation rate of less than 100 when the evaporation rate of butyl acetate is set to 100. Examples of solvents with a fast evaporation rate include methyl isobutyl ketone (evaporation rate 160), toluene (evaporation rate 200), and methyl ethyl ketone (evaporation rate 370). Examples of solvents with a slow evaporation rate of less than 100 include cyclohexanone (evaporation rate 32) and propylene glycol monomethyl ether acetate (evaporation rate 44). It is preferable that the solvent in the coating solution for the anti-glare layer be mainly composed of a solvent with a fast evaporation rate. By increasing the evaporation rate of the solvent, it is possible to suppress the sinking of particles to the bottom of the anti-glare layer, and furthermore, to suppress the flow of the binder resin between the protrusions based on the particles. Therefore, the randomness effect described above, due to two types of inorganic particles with different d50 values, can be easily achieved. The main component means that it accounts for 50% or more by mass of the total amount of the solvent, preferably 70% or more by mass, more preferably 80% or more by mass, and even more preferably 85% or more by mass. On the other hand, if the entire amount of the solvent is a solvent with a fast evaporation rate, the solvent will volatilize rapidly, making it difficult to control the surface shape. For this reason, it is preferable to include 1 to 20 parts by mass of a solvent with a slow drying rate, and more preferably 2 to 12 parts by mass, per 100 parts by mass of a solvent with a fast evaporation rate.

[0099] When forming an anti-glare layer from an anti-glare coating liquid, it is preferable to control the drying conditions. The drying conditions can be controlled by the drying temperature and the wind speed in the dryer. The drying temperature is preferably 30°C to 120°C, and the drying wind speed is preferably 0.2 m / s to 50 m / s. In addition, in order to control the surface shape of the anti-glare layer through drying, it is preferable to irradiate with ionizing radiation after the coating liquid has dried. It is preferable to carry out two drying stages within the above temperature and wind speed ranges. In addition, it is preferable to use a higher drying temperature and a stronger wind speed in the second drying stage compared to the first drying stage. By drying slowly in the first stage, it is possible to make it easier for the shape of the amorphous inorganic particles to be reflected on the surface of the binder resin when the binder resin covers the surface of the amorphous inorganic particles. Also, by using a higher drying temperature and a stronger wind speed in the second drying stage than in the first drying stage, it is possible to suppress particle aggregation. Therefore, by using a two-stage drying process, the randomness effect described above, caused by two types of inorganic particles with different d50 values, can be more easily achieved. For the first stage of drying, it is preferable to set the drying temperature to 30°C or higher and less than 60°C, and the drying air velocity to 0.2 m / s or higher and less than 7 m / s. For the second stage of drying, it is preferable to set the drying temperature to 60°C or higher and 120°C or lower, and the drying air velocity to 7 m / s or higher and 50 m / s or lower.

[0100] Anti-reflective layer The anti-reflective layer is preferably located on the outermost surface of the first surface. Examples of anti-reflective layers include a single-layer structure of a low refractive index layer; a two-layer structure of a high refractive index layer and a low refractive index layer; and a multilayer structure of three or more layers. The low refractive index layer and the high refractive index layer can be formed by a general-purpose wet method or dry method. In the case of the wet method, the single-layer or two-layer structure is preferred, and in the case of the dry method, the multilayer structure is preferred. The wet method is superior to the dry method in terms of production efficiency and chemical resistance. In the optical film of this disclosure, the anti-reflective layer is preferably a single-layer structure of a low refractive index layer in order to easily maintain the uneven shape of the anti-glare layer.

[0101] ―In the case of a single-layer or two-layer structure― A single-layer structure is a single layer of low refractive index, and a two-layer structure is formed from a high refractive index layer and a low refractive index layer. Single-layer or two-layer structures are preferably formed by a wet method. Methods for forming an anti-reflective layer by a wet method include forming it by a sol-gel method using metal alkoxides, forming it by coating it with a low refractive index resin such as fluororesin, and forming it by coating a binder resin composition with a coating solution containing low refractive index particles or high refractive index particles. Among the wet methods, it is preferable to form the anti-reflective layer with a binder resin composition and a coating solution containing low refractive index particles or high refractive index particles for adhesion and scratch resistance. That is, it is preferable that the low refractive index layer contains a binder resin and low refractive index particles. It is also preferable that the high refractive index layer contains a binder resin and high refractive index particles.

[0102] The refractive index of the low refractive index layer is preferably 1.10 or higher at the lower limit, more preferably 1.20 or higher, more preferably 1.26 or higher, more preferably 1.28 or higher, and more preferably 1.30 or higher. The upper limit is preferably 1.48 or lower, more preferably 1.45 or lower, more preferably 1.40 or lower, more preferably 1.38 or lower, and more preferably 1.32 or lower. In this specification, the refractive index refers to the value at a wavelength of 550 nm.

[0103] The thickness of the low refractive index layer is preferably 80 nm or more at the lower limit, more preferably 85 nm or more, and more preferably 90 nm or more. The upper limit is preferably 150 nm or less, more preferably 110 nm or less, and more preferably 105 nm or less.

[0104] The binder resin of the low refractive index layer preferably contains a cured product of a curable resin composition, such as a cured product of a thermosetting resin composition or a cured product of an ionizing radiation-curable resin composition, in order to improve scratch resistance, and more preferably contains a cured product of an ionizing radiation-curable resin composition. The binder resin of the low refractive index layer may also contain a thermoplastic resin to the extent that it does not impair the effects of this disclosure.

[0105] Examples of cured products of the curable resin composition for the low refractive index layer include those similar to the cured products of the curable resin composition exemplified for the anti-glare layer. The ratio of the cured product of the curable resin composition to the total amount of binder resin for the low refractive index layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 97% by mass or more.

[0106] The binder resin for the low refractive index layer may contain a thermoplastic resin to adjust the viscosity of the coating solution for the low refractive index layer. The thermoplastic resin content is preferably 10% by mass or less of the total amount of the binder resin, more preferably 7% by mass or less, and even more preferably 5% by mass or less, for the above-mentioned effects and coating film strength.

[0107] Examples of thermoplastic resins include polystyrene resins, polyolefin resins, ABS resins (including heat-resistant ABS resins), AS resins, AN resins, polyphenylene oxide resins, polycarbonate resins, polyacetal resins, acrylic resins, polyethylene terephthalate resins, polybutylene terephthalate resins, polysulfone resins, and polyphenylene sulfide resins, with acrylic resins being preferred from the viewpoint of transparency. The weight-average molecular weight of the thermoplastic resin is preferably 20,000 to 200,000, more preferably 30,000 to 150,000, and even more preferably 50,000 to 100,000.

[0108] Low refractive index particles include hollow particles and solid particles. The low refractive index particles may consist of only one of the two, but it is preferable to include hollow particles in order to lower the refractive index. In order to suppress the decrease in the strength of the coating film of the low refractive index layer, solid particles may be included in addition to hollow particles. The material of the hollow particles and solid particles may be any inorganic compound such as silica and magnesium fluoride, or an organic compound, but silica is preferred for lower refractive index and strength. In other words, it is preferable for the low refractive index layer to contain hollow silica particles. Furthermore, it is also preferable for the low refractive index layer to contain solid silica particles in addition to hollow silica particles.

[0109] The average primary particle diameter of hollow particles is preferably smaller than the thickness of the low refractive index layer, for example, 1 nm to 150 nm. The average primary particle diameter of hollow particles is preferably 35 nm to 130 nm, more preferably 50 nm to 120 nm, and even more preferably 60 nm to 100 nm. The average primary particle diameter of solid particles is preferably smaller than the thickness of the low refractive index layer, for example, 0.5 nm to 100 nm. The average primary particle diameter of solid particles is preferably 1 nm to 30 nm, more preferably 5 nm to 20 nm, and even more preferably 10 nm to 15 nm.

[0110] The average primary particle diameter of hollow particles, solid particles (described later), and high-refractive-index particles (described later) is calculated by the following steps (F1) to (F3). (F1) The cross-section of the optical film is imaged using a TEM or STEM. The acceleration voltage of the TEM or STEM is set to 10kV to 30kV, and the magnification to 50,000 to 300,000 times. (F2) Ten arbitrary particles are extracted from the observed image, and the particle diameter of each particle is calculated. The particle diameter of each particle is defined as the distance at which the distance between two arbitrary parallel lines is maximized when the cross-section of the particle is enclosed by these two lines. (F3) The same procedure is performed five times on observation images of the same sample from different screens, and the average value obtained from the number average of the particle diameters of a total of 50 particles is taken as the average primary particle diameter of the particles.

[0111] The higher the content of hollow particles, the higher the filling rate of hollow particles in the binder resin, and the lower the refractive index of the low refractive index layer. For this reason, the content of hollow particles is preferably 80 parts by mass or more, and more preferably 100 parts by mass or more, per 100 parts by mass of binder resin. On the other hand, if the content of hollow particles is too high, the hollow particles tend to be damaged or fall off easily, and the mechanical strength, such as scratch resistance, of the low refractive index layer tends to decrease. For this reason, the content of hollow particles is preferably 300 parts by mass or less, and more preferably 200 parts by mass or less, per 100 parts by mass of binder resin.

[0112] The content of solid particles is preferably 10 parts by mass or more, and more preferably 20 parts by mass or more, per 100 parts by mass of binder resin, in order to improve the scratch resistance of the low refractive index layer. On the other hand, if the content of solid particles is too high, the solid particles tend to aggregate. For this reason, the content of solid particles is preferably 80 parts by mass or less, and more preferably 40 parts by mass or less, per 100 parts by mass of binder resin.

[0113] The low refractive index layer and the high refractive index layer may contain additives such as antistatic agents, leveling agents, ultraviolet absorbers, light stabilizers, antioxidants, viscosity modifiers, and thermal polymerization initiators, as needed.

[0114] It is preferable to place the high refractive index layer on the anti-glare layer side rather than the low refractive index layer. The refractive index of the high refractive index layer is preferably 1.53 or higher at the lower limit, more preferably 1.54 or higher, more preferably 1.55 or higher, and more preferably 1.56 or higher, and the upper limit is preferably 1.85 or lower, more preferably 1.80 or lower, more preferably 1.75 or lower, and more preferably 1.70 or lower.

[0115] The upper limit of the high refractive index layer is preferably 200 nm or less, more preferably 180 nm or less, and even more preferably 150 nm or less. The lower limit is preferably 50 nm or more, and more preferably 70 nm or more.

[0116] Examples of binder resins for high refractive index layers include those similar to those used for low refractive index layers.

[0117] Examples of high refractive index particles include antimony pentoxide, zinc oxide, titanium oxide, cerium oxide, tin-doped indium oxide, antimony-doped tin oxide, yttrium oxide, and zirconium oxide. The average primary particle diameter of the high refractive index particles is preferably 2 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. Furthermore, from the viewpoint of suppressing whitening and transparency, the average primary particle diameter of the high refractive index particles is preferably 200 nm or less, more preferably 100 nm or less, more preferably 80 nm or less, more preferably 60 nm or less, and more preferably 30 nm or less. The content of high refractive index particles should be such that the refractive index of the high refractive index layer falls within the above-mentioned range.

[0118] When forming anti-reflective layers such as low-refractive-index layers and high-refractive-index layers by a wet method, it is preferable to lower the viscosity of the coating solution for the anti-reflective layer. Lowering the viscosity of the coating solution for the anti-reflective layer makes it easier for the coating solution to level with the surface shape of the anti-glare layer. Therefore, even when an anti-reflective layer is formed on an anti-glare layer, the surface shape of the anti-glare layer can be easily reflected in the surface shape of the first surface of the optical film. For example, the viscosity of the coating solution for the anti-reflective layer can be lowered by increasing the proportion of monomers in the ionizing radiation-curable resin composition, increasing the proportion of solvent in the coating solution, or selecting a solvent with low viscosity as the solvent for the coating solution.

[0119] The solvent for the anti-reflective coating solution is the same as that exemplified for the anti-glare coating solution. The proportion of the solvent in the anti-reflective coating solution is preferably 90.0% by mass or more and 99.5% by mass or less, more preferably 92.0% by mass or more and 99.3% by mass or less, and even more preferably 94.0% by mass or more and 99.0% by mass or less.

[0120] When forming an anti-reflective layer from an anti-reflective coating solution, it is preferable to control the drying conditions. The drying conditions can be controlled by the drying temperature and the airflow velocity in the dryer. The drying temperature is preferably 30°C to 70°C, and the drying airflow velocity is preferably 10 m / s to 30 m / s. By lowering the drying temperature, a rapid increase in the viscosity of the anti-reflective coating solution can be suppressed. Also, by lowering the airflow velocity, the viscosity of the anti-reflective coating solution can be increased gradually. Therefore, by drying the anti-reflective coating solution at a relatively low temperature and with a low airflow velocity, it is possible to maintain the surface shape of the anti-glare layer. Ionizing radiation irradiation is preferably performed after the anti-reflective coating solution has dried.

[0121] —In the case of a multilayer structure with three or more layers— A multilayer structure preferably formed by the dry method is one in which high refractive index layers and low refractive index layers are alternately stacked in a total of three or more layers. Even in a multilayer structure, it is preferable to place the low refractive index layer on the outermost surface of the optical film.

[0122] The high refractive index layer preferably has a thickness of 10 nm to 200 nm and a refractive index of 2.10 to 2.40. More preferably, the thickness of the high refractive index layer is 20 nm to 70 nm. The low refractive index layer preferably has a thickness of 5 nm to 200 nm and a refractive index of 1.33 to 1.53. More preferably, the thickness of the low refractive index layer is 20 nm to 120 nm.

[0123] <Optical Properties> The optical film of this disclosure preferably has a haze of 20% or more and 75% or less according to JIS K7136:2000. The lower limit of the haze is more preferably 30% or more, even more preferably 40% or more, even more preferably 50% or more, and the upper limit is more preferably 70% or less, and even more preferably 65% ​​or less. Setting the haze to 20% or more makes it easier to improve anti-glare properties. Also, setting the haze to 75% or less makes it easier to suppress a decrease in image resolution. The light incident surface when measuring haze, total light transmittance, and transmitted image clarity is the second surface side of the optical film.

[0124] The optical film of this disclosure preferably has an internal haze of 35% or less, more preferably 20% or less, even more preferably 15% or less, and even more preferably 10% or less, in order to facilitate the improvement of image resolution and contrast.

[0125] In this specification, internal haze is measured by the following means (1) to (3): (1) A sample is prepared in which the irregularities of the first surface of an optical film are flattened by laminating a transparent sheet to the first surface side of the optical film via an adhesive layer. (2) The haze of the sample is measured. (3) The measurement value in (2) is taken as the internal haze of the optical film. However, if the transparent sheet and the adhesive layer have haze, the value obtained by subtracting the haze of the transparent sheet and the adhesive layer from the measurement value in (2) is taken as the internal haze of the optical film. In (3) above, the haze of the transparent sheet and the adhesive layer is measured by the following means (3-1) to (3-2): (3-1) A laminate is prepared in which the transparent sheet is laminated to a sheet with known haze via an adhesive layer. (3-2) The value obtained by subtracting the haze of the sheet with known haze from the haze of the laminate is taken as the haze of the transparent sheet and the adhesive layer.

[0126] In (1) above, the difference between the refractive index of the adhesive layer of the sample and the refractive index of the binder resin of the first surface layer of the optical film shall be 0.05 or less. Preferably, the difference shall be 0.03 or less, and more preferably, 0.01 or less. In (1) above, the difference between the refractive index of the adhesive layer of the sample and the refractive index of the transparent sheet shall be 0.05 or less. Preferably, the difference shall be 0.03 or less, and more preferably, 0.01 or less. In (3-1) above, the difference between the refractive index of the adhesive layer and the refractive index of the sheet with known haze shall be 0.05 or less. Preferably, the difference shall be 0.03 or less, and more preferably, 0.01 or less.

[0127] The optical film of this disclosure preferably has a total light transmittance of 80% or more, more preferably 85% or more, and even more preferably 90% or more, according to JIS K7361-1:1997.

[0128] The optical film disclosed herein has a transmission image clarity measured in accordance with JIS K7374:2007, with respect to the transmission image clarity of an optical comb width of 0.125 mm, which is C 0.125 The optical comb width is 0.25 mm, and the transmitted image clarity is C 0.25The optical comb width is 0.5 mm, and the transmitted image clarity is C 0.5 The optical comb width is 1.0 mm, and the transmitted image clarity is C 1.0 The optical comb width is 2.0 mm, and the transmitted image clarity is C 2.0 When defined as C 0.125 , C 0.25 , C 0.5 , C 1.0 and C 2.0 The value of is preferably within the following range.

[0129] C 0.125 To improve anti-glare properties, the concentration is preferably 50% or less, more preferably 40% or less, more preferably 30% or less, and more preferably 20% or less. 0.125 To improve resolution, a value of 1.0% or higher is preferable. 0.25 To improve anti-glare properties, the concentration is preferably 50% or less, more preferably 40% or less, more preferably 30% or less, and more preferably 20% or less. 0.25 To improve resolution, a value of 1.0% or higher is preferable. 0.5 To improve anti-glare properties, the concentration is preferably 50% or less, more preferably 40% or less, more preferably 30% or less, and more preferably 20% or less. 0.5 To improve resolution, a value of 1.0% or higher is preferable. 1.0 To improve anti-glare properties, the concentration is preferably 50% or less, more preferably 40% or less, more preferably 30% or less, and more preferably 20% or less. 1.0 To improve resolution, a value of 1.0% or higher is preferable. 2.0 To improve anti-glare properties, the concentration is preferably 60% or less, more preferably 40% or less, more preferably 30% or less, and more preferably 20% or less. 2.0 To improve resolution, a concentration of 5.0% or more is preferable. The optical film of this disclosure has a concentration of C to improve anti-glare properties. 0.125 , C 0.5 , C 1.0 and C 2.0The sum of these values ​​is preferably 200% or less, more preferably 150% or less, more preferably 130% or less, more preferably 100% or less, and more preferably 80% or less. The sum of these values ​​is preferably 10.0% or more in order to improve resolution.

[0130] In the optical film disclosed herein, a sample for gloss measurement is prepared by adhering a black plate to the second surface side of the optical film using an air suction method, and it is preferable that the 60-degree specular gloss measured from the first surface side of the sample is 5.0% or more and 80.0% or less. More preferably, the 60-degree specular gloss is 10.0% or more and 50.0% or less, and even more preferably 20.0% or more and 35.0% or less. By setting the 60-degree specular gloss to 5.0% or more, it is easier to prevent the resolution from becoming too low. By setting the 60-degree specular gloss to 80.0% or less, it is easier to improve the anti-glare properties. In this specification, the 60-degree specular gloss means the value measured by method 3 of JIS Z8741:1997.

[0131] The optical film of this disclosure preferably has a reflectance of 0.30% or more and 3.00% or less, as measured by the SCI method from the first surface side of the first sample. More preferably, the reflectance measured by the SCI method is 0.60% or more and 2.00% or less, and even more preferably 1.00% or more and 1.50% or less. By setting the reflectance measured by the SCI method to 0.30% or more, it is easier to suppress ΔEab from becoming too large. By setting the reflectance measured by the SCI method to 3.00% or less, it is easier to enhance the blackness of the black display area in an environment where strong light does not incident on the first surface, thereby making it easier to improve contrast.

[0132] SCI is an abbreviation for Specular Component Include, and refers to reflected light that contains a component that is specularly reflected from the sample. In this specification, SCI shall be measured in accordance with geometric condition c of JIS Z8722:2009. <Geometric condition c of JIS Z8722:2009> The sample is irradiated uniformly from all directions, and reflected light is received in directions where the angle with the normal to the sample surface is 10° or less. In this case, the received light beam shall not contain rays that are tilted at an angle of 5° or more with respect to its center line. Furthermore, it is desirable that the direction of reception does not coincide with the normal to the sample.

[0133] The optical film of this disclosure preferably has a reflectance of 0.15% or more and 2.00% or less, measured by the SCE method from the first surface side of the first sample. More preferably, the reflectance measured by the SCE method is 0.33% or more and 2.00% or less, more preferably 0.40% or more and 1.70% or less, and even more preferably 0.60% or more and 1.40% or less. By setting the reflectance measured by the SCE method to 0.15% or more, it is easier to suppress ΔEab from becoming too large. By setting the reflectance measured by the SCE method to 2.00% or less, it is easier to suppress the screen from becoming whitish.

[0134] SCE is an abbreviation for Specular Component Exclude, and it is the reflected light obtained by removing the specular reflection component from the sample from the received reflected light. In this specification, SCE shall be measured in accordance with geometric condition c of JIS Z8722:2009.

[0135] The optical film of this disclosure preferably has a reflectance of 0.10 or more and 0.99 or less when measured by the SCE method / reflectance when measured by the SCI method, more preferably 0.30 or more and 0.90 or less, and even more preferably 0.50 or more and 0.80 or less.

[0136] <Size, Shape, etc.> The optical film may be in the form of a single sheet cut to a predetermined size, or in the form of a roll wound from a long sheet. The size of the sheet is not particularly limited, but the maximum diameter is approximately 2 inches to 500 inches. "Maximum diameter" refers to the maximum length when connecting any two points on the optical film. For example, if the optical film is rectangular, the diagonal of the rectangle is the maximum diameter. If the optical film is circular, the diameter of the circle is the maximum diameter. The width and length of the roll are not particularly limited, but generally the width is approximately 500 mm to 3000 mm, and the length is approximately 500 m to 5000 m. The optical film in roll form can be cut into single sheets to match the size of an image display device, etc. When cutting, it is preferable to exclude the roll ends, which have unstable physical properties. The shape of the sheet is also not particularly limited, and examples include polygons such as triangles, squares, and pentagons, circles, and random irregular shapes. More specifically, if the optical film is rectangular, the aspect ratio is not particularly limited as long as it does not pose a problem as a display screen. For example, aspect ratios such as width:height = 1:1, 4:3, 16:10, 16:9, 2:1 are possible, but in automotive applications and digital signage where design is important, the aspect ratio is not limited to these.

[0137] The surface shape of the second surface of the optical film is not particularly limited, but it is preferably substantially smooth. Substantially smooth means that the arithmetic mean roughness Ra of JIS B0601:1994 at a cutoff value of 0.8 mm is less than 0.03 μm, and preferably 0.02 μm or less.

[0138] [Polarizing plate] The polarizing plate of the present disclosure is a polarizing plate having a polarizer, a first transparent protective plate disposed on one side of the polarizer, and a second transparent protective plate disposed on the other side of the polarizer, wherein at least one of the first transparent protective plate and the second transparent protective plate is the optical film of the present disclosure described above, and the second surface of the optical film and the polarizer are disposed opposite each other.

[0139] <Polarizers> Examples of polarizers include sheet-type polarizers such as polyvinyl alcohol film, polyvinyl formal film, polyvinyl acetal film, and ethylene-vinyl acetate copolymer saponified film, which are dyed with iodine or the like and stretched; wire grid-type polarizers consisting of numerous parallel metal wires; coated polarizers coated with lyotropic liquid crystal or dichroic guest-host materials; and multilayer thin-film polarizers. These polarizers may also be reflective polarizers that have the function of reflecting polarization components that do not transmit through them.

[0140] <Transparent protective plate> A first transparent protective plate is placed on one side of the polarizer, and a second transparent protective plate is placed on the other side. At least one of the first transparent protective plate and the second transparent protective plate is the optical film of the present disclosure as described above. In the polarizer of the present disclosure, one of the first transparent protective plate and the second transparent protective plate may be the optical film of the present disclosure as described above, or both the first transparent protective plate and the second transparent protective plate may be the optical film of the present disclosure as described above.

[0141] Of the first and second transparent protective plates, the transparent protective plate that is not the optical film of this disclosure can be a general-purpose plastic film, glass, or the like.

[0142] It is preferable to bond the polarizer and the transparent protective plate together using an adhesive. A general-purpose adhesive can be used, and a PVA-based adhesive is preferred.

[0143] [Surface plate for image display device] The surface plate for an image display device according to the present disclosure is a surface plate for an image display device in which a protective film is bonded to a resin plate or a glass plate, wherein the protective film is the optical film according to the present disclosure described above, and the second surface of the optical film and the resin plate or glass plate are arranged facing each other.

[0144] As the resin plate or glass plate, a resin plate or glass plate commonly used as a surface plate for image display devices can be used.

[0145] The thickness of the resin or glass plate is preferably 10 μm or more to ensure good strength. The upper limit of the thickness of the resin or glass plate is usually 5000 μm or less. For thinning, the upper limit of the thickness of the resin or glass plate is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 100 μm or less. Embodiments of the thickness range of the resin or glass plate include 10 μm to 5000 μm, 10 μm to 1000 μm, 10 μm to 500 μm, and 10 μm to 100 μm.

[0146] [Image Display Panel] The image display panel of the present disclosure is an image display panel having a display element and an optical film disposed on the light-emitting surface side of the display element, wherein the optical film includes the optical film of the present disclosure described above (see Figure 2).

[0147] Within the image display panel, it is preferable that the optical film of this disclosure is arranged such that its second surface faces the display element. Within the image display panel, it is preferable that the optical film of this disclosure is placed on the outermost surface on the light-emitting surface side of the display element.

[0148] Examples of display elements include EL display elements such as organic EL display elements and inorganic EL display elements, liquid crystal display elements, plasma display elements, and LED display elements such as micro LED display elements. These display elements may have a touch panel function inside the display element. Examples of liquid crystal display methods for liquid crystal display elements include IPS method, VA method, multi-domain method, OCB method, STN method, TSTN method, etc.

[0149] An image display panel in which the display element is a micro-LED display element has a configuration in which multiple small panels, each approximately 10 cm x 10 cm in size, are arranged without gaps. Therefore, in an image display panel using micro-LED display elements, if there are slight differences in quality among the panels, the boundaries between the panels may be visible as lines. However, the image display panel disclosed herein can suppress the visibility of the boundaries between the panels as lines, even if the display element is a micro-LED display element.

[0150] Furthermore, the image display panel of this disclosure may also be an image display panel with a touch panel, having a touch panel between the display element and the optical film.

[0151] The size of the image display panel is not particularly limited, but the maximum diameter is approximately 2 inches to 500 inches. The maximum diameter refers to the maximum length when connecting any two points within the surface of the image display panel.

[0152] [Image Display Device] The image display device of this disclosure includes the image display panel of this disclosure.

[0153] The image display device of the present disclosure is not particularly limited as long as it includes the image display panel of the present disclosure. Preferably, the image display device of the present disclosure comprises the image display panel of the present disclosure, a drive control unit electrically connected to the image display panel, and a housing housing the same. If the display element is a liquid crystal display element, the image display device of the present disclosure requires a backlight. The backlight is positioned on the side opposite to the light-emitting surface of the liquid crystal display element.

[0154] The size of the image display device is not particularly limited, but the maximum diameter of the effective display area is approximately 2 inches to 500 inches. The effective display area of ​​an image display device is the area in which an image can be displayed. For example, if the image display device has a housing that surrounds the display element, the area inside the housing becomes the effective image area. The maximum diameter of the effective image area refers to the maximum length when connecting any two points within the effective image area. For example, if the effective image area is rectangular, the diagonal of the rectangle becomes the maximum diameter. If the effective image area is circular, the diameter of that area becomes the maximum diameter.

[0155] This disclosure includes the following <1> to <19>. <1> An optical film having a first surface and a second surface which is opposite to the first surface, wherein the optical film has an anti-reflective layer and an anti-glare layer in that order from the first surface to the second surface, the first surface has an uneven shape, and the maximum value of six Δab calculated by the following formula 1 is 0.20 or more and 2.50 or less. <Formula 1> Δab = {(a ｎ -a ｎ＋１ ) ２ + (bｎ -b ｎ＋１ ) ２} １／２ (In Equation 1, a ｎ This is the a of the Lab color system calculated from the reflected light in the nth measurement direction in the first measurement described below. ＊ The value is shown, a ｎ＋１ This is the a of the Lab color system calculated from the reflected light in the (n+1)th measurement direction in the first measurement described below. ＊ The value is shown, b ｎ This is the b of the Lab color system calculated from the reflected light in the nth measurement direction in the first measurement described below. ＊ The value is shown, b ｎ＋１ This is the b of the Lab color system calculated from the reflected light in the (n+1)th measurement direction in the first measurement described below. ＊ The value is shown. In Equation 1, n is an integer between 1 and 6.) <First Measurement> A first sample is prepared by bonding a black plate to the second surface side of the optical film via an adhesive layer. One side of the first sample is the first surface of the optical film. The normal direction of the first surface of the first sample is set to 0 degrees. Using a bending-angle spectrophotometer, parallel light rays are shone from the +45 degree direction on the first surface side of the first sample, and the reflected light of the parallel light rays is measured in seven directions: -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, and -60 degrees. With -30 degrees as the first measurement direction and -60 degrees as the seventh measurement direction, the L of the Lab color system is measured from the reflected light of the first to seventh measurement directions. ＊ Value, a ＊ Value and b ＊ Calculate the value. <2> The optical film according to <1>, wherein the minimum value of the six Δab calculated by formula 1 is 0.02 or more and 0.50 or less. <3> In the first measurement, the a of the Lab color system calculated from the reflected light of the first to seventh measurement directions. ＊ The maximum value of a ＊ MAX and a ＊ The minimum value of a ＊The optical film according to <1> or <2>, wherein the absolute value of the difference from MIN is 0.25 or more and 3.00 or less. <4> In the first measurement, the b of the Lab color system calculated from the reflected light of the 1st to 7th measurement directions, respectively. ＊ The maximum value is b ＊ MAX and b ＊ The minimum value of b ＊ An optical film according to any of <1> to <3>, wherein the absolute value of the difference from MIN is 0.30 or more and 3.50 or less. <5> In the first measurement, the L of the Lab color system calculated from the reflected light of the 1st to 7th measurement directions, respectively. ＊ The maximum value is L ＊ An optical film according to any of <1> to <4>, wherein the product of MAX and the haze of the optical film according to JIS K7136:2000 is 850 or less. <6> An optical film according to any of <1> to <5>, wherein ΔEab in the following formula 2 is 4.80 or more and 20.00 or less. <Formula 2> ΔEab = {(L ５ -L ６０ ) ２ + (a ５ -a ６０ ) ２ + (b ５ -b ６０ ) ２} １／２ (However, in Equation 2, L ５ a ５ , b ５ , L ６０ a ６０ and b ６０ This refers to the value obtained in the second measurement described below.) <Second Measurement> The normal direction of the first surface of the first sample is set to 0 degrees. Using a bending spectrophotometer, parallel light rays are shone onto the first sample from a direction of +5 degrees on the first surface side, and the reflected light of the parallel light rays is measured at a direction of -5 degrees. The L of the Lab color system is calculated from the measured reflected light at -5 degrees. ＊ Value, a ＊ Value and b ＊ The values ​​are L ５ a ５ , b ５The first sample is irradiated with parallel light rays from the +60-degree direction on the first surface side using the bending angle spectrophotometer, and the reflected light of the parallel rays is measured in the -60-degree direction. The L of the Lab color system is calculated from the measured reflected light at -60 degrees. ＊ Value, a ＊ Value and b ＊ The values ​​are L ６０ a ６０ and b ６０The following applies: <7> An optical film according to any of <1> to <6>, wherein the haze of JIS K7136:2000 is 20% or more and 75% or less. <8> An optical film according to any of <1> to <7>, wherein a sample for gloss measurement is prepared by adhering a black plate to the second surface side of the optical film by the air suction method, and the 60-degree specular gloss measured from the first surface side of the sample is 5.0% or more and 80.0% or less. <9> An optical film according to any of <1> to <8>, wherein the reflectance measured from the first surface side of the first sample by the SCI method is 0.30% or more and 3.00% or less. <10> An optical film according to any of <1> to <9>, wherein the reflectance measured from the first surface side of the first sample by the SCE method is 0.15% or more and 2.00% or less. <11> The optical film according to any one of <1> to <10>, wherein the first surface has a height average of 0.03 μm or more and a height coefficient of variation of 0.50 or more. <12> The optical film according to any one of <1> to <11>, wherein the first surface has a slope average of 25.0 μm / mm or more and a slope coefficient of variation of 0.30 or more. <13> The optical film according to any one of <1> to <12>, wherein the anti-glare layer contains a binder component and particles. <14> The optical film according to any one of <1> to <13>, further comprising a substrate, wherein the anti-reflective layer, the anti-glare layer and the substrate are arranged in this order from the first surface to the second surface. <15> A polarizing plate having a polarizer, a first transparent protective plate disposed on one side of the polarizer, and a second transparent protective plate disposed on the other side of the polarizer, wherein at least one of the first transparent protective plate and the second transparent protective plate is an optical film according to any of <1> to <14>, and the second surface of the optical film and the polarizer are arranged facing each other. <16> A surface plate for an image display device having a protective film laminated on a resin plate or a glass plate, wherein the protective film is an optical film according to any of <1> to <14>, and the second surface of the optical film and the resin plate or the glass plate are arranged facing each other.<17> An image display panel having a display element and an optical film disposed on the light-emitting surface side of the display element, wherein the optical film includes the optical film described in any of <1> to <14>. <18> The image display panel according to <17>, wherein the display element is a microLED display element. <19> An image display device including the image display panel according to <17> or <18>.

[0156] Next, the present disclosure will be described in more detail by examples, but the present disclosure is not limited in any way by these examples. Unless otherwise specified, "parts" and "%" refer to mass.

[0157] 1. Measurement and Evaluation The optical films of the examples and comparative examples were measured and evaluated as follows. The atmosphere during each measurement and evaluation was set to a temperature of 23°C and a relative humidity of 40% to 65%. In addition, before starting each measurement and evaluation, the target sample was exposed to the above atmosphere for 30 minutes before measurement and evaluation.

[0158] 1-1. The optical films of the first measurement, the second measurement example, and the comparative example were cut into 5 cm x 5 cm pieces. The cutting locations were selected randomly after visually confirming that there were no abnormalities such as dust or scratches. The first sample was prepared by attaching the substrate side of the cut optical film to a black board measuring 5 cm x 5 cm (Nitto Resin Industry Co., Ltd., product name: Clarex N-885 (black), thickness 1 mm) via a transparent optical adhesive sheet from Panac Co., Ltd. (product name: Panaclean PD-S1, thickness 25 μm).

[0159] <First Measurement> Using a variable-angle spectrophotometer (manufactured by JASCO Corporation, main unit: V-780DS, accessory: automatic absolute reflectance measurement unit ARMN-921i, light source: D65, field of view: 2 degrees), parallel light rays were shone from a direction of +45 degrees on the first surface side of the first sample, and the reflected light of the parallel light rays was measured in seven directions: -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, and -60 degrees. The two light beam masks inside the sample chamber of the main unit were removed. The reflected light was measured at an aperture angle of 10 degrees. The setting conditions for the variable-angle spectrophotometer are shown below. With -30 degrees as the first measurement direction and -60 degrees as the seventh measurement direction, the L of the Lab color system was measured from the reflected light of the first to seventh measurement directions. ＊ Value, a ＊ Value and b ＊ The values ​​were calculated. From the above measurement results, the maximum value of Δab, the minimum value of Δab, and a ＊ MAX, a ＊ MIN, b ＊ MAX, b ＊ MIN, L ＊ MAX and ΔEab were calculated. The software used for the analysis was version 2 of "Spectra Manager" (product name) manufactured by JASCO Corporation.

[0160] <Second Measurement> Using a variable-angle spectrophotometer (manufactured by JASCO Corporation, main unit: V-780DS, accessory: automatic absolute reflectance measurement unit ARMN-921i, light source: D65, field of view: 2 degrees), parallel light rays were irradiated onto the first surface of the first sample from a direction of +5 degrees, and the reflected light of the parallel rays was measured at a direction of -5 degrees. The two light beam masks inside the sample chamber of the main unit were removed. The reflected light was measured at an aperture angle of 10 degrees. The settings for the variable-angle spectrophotometer are shown below. Using the variable-angle spectrophotometer, parallel light rays were irradiated onto the first surface of the first sample from a direction of +60 degrees, and the reflected light of the parallel rays was measured at a direction of -60 degrees. The reflected light was measured at an aperture angle of 10 degrees. ΔEab was calculated from the above measurement results. Version 2 of "Spectra Manager" (product name) from JASCO Corporation was used for the analysis software.

[0161] <Parameter Settings> <Absolute Reflection Settings Tab> - Placement: Reflection - Measurement Position Setting: Arbitrary - Detection Angle Setting: Select "Asynchronous" for the first measurement. Select "Synchronized" for the second measurement.・Polarizer: N polarization 《Basic Tab》 ・Photometric mode: %R ・UV / Vis bandwidth: 5.0nm ・NIR bandwidth: 10.0nm ・UV / Vis response: 0.24sec ・NIR response: 0.24sec ・Start wavelength: 780nm ・End wavelength: 380nm ・Data acquisition interval: 0.5nm ・Scanning mode: Continuous ・Scanning speed: 1000nm / min ・Vertical axis scale: Automatic ・Number of integrations: 1 《Correction Tab》 ・Correction: Baseline / Dark 《Control Tab》 ・Switching wavelength: Light source 340nm, Detector / Diffraction grating 850nm ・Light source: Automatic (Both D2 lamp and WI lamp are lit) ・Filter switching: Stop scanning at the filter switching wavelength <Ingress space> ・None <Exit space> ・None <Observation conditions> ・Color system: Lab ・Light source: D65 ・Standard: JIS Z8781-1:2012, JIS Z8701:1999 • Field of view: 2 degrees • Calculation range: 380–780 nm • Data interval: 5 nm

[0162] Prior to the first and second measurements described above, the following operations m1 to m3 were performed. m1: Select absolute reflectance spectrum measurement on the screen of the analysis software for the bending-angle spectrophotometer (product name: Spectra Manager version 2, manufactured by JASCO Corporation). m2: Place the attached black metal plate in the sample holder of the bending-angle spectrophotometer and perform a dark measurement. Remove the black metal plate after performing the dark measurement. m3: Perform a baseline measurement with nothing placed in the sample holder.

[0163] 1-2. Total light transmittance, haze, internal haze. The optical films of the examples and comparative examples were cut into 10 cm squares. The cutting locations were selected randomly after visually confirming that there were no abnormalities such as dust or scratches. Using a haze meter (HM-150, manufactured by Murakami Color Technology Laboratory), the total light transmittance of each sample according to JIS K7361-1:1997 and the haze according to JIS K7136:2000 were measured under the following conditions. Next, samples were prepared in which the uneven shape was flattened by attaching an 80 μm thick TAC film (manufactured by Fujifilm Corporation, TD80UL) to the surface of the low refractive index layer side of the optical films of the examples and comparative examples via a transparent adhesive (manufactured by Panac Co., Ltd., PD-S1, thickness 25 μm) to eliminate the influence of haze caused by the surface shape. The haze of the samples according to JIS K7136:2000 was measured, and the obtained value was defined as the internal haze. <Conditions> To stabilize the light source, the device was calibrated after waiting at least 15 minutes after turning on the power switch, with nothing placed in the inlet opening where the measurement sample would be placed. After that, the measurement sample was placed in the inlet opening and the haze was measured. The light incident surface during measurement was the substrate side.

[0164] 1-3. Transmitted Image Clarity Samples for measurement were prepared by cutting the optical films of the examples and comparative examples into 10 cm squares. The cutting locations were selected randomly after visually confirming that there were no abnormalities such as dust or scratches. The transmitted image clarity of each sample according to JIS K7374:2007 was measured using a Suga Test Instruments Co., Ltd. image clarity meter (product name: ICM-1T). The light incident surface was the substrate side. Transmitted image clarity (C) with an optical comb width of 0.125 mm 0.125 ), the transmitted image clarity (C) of the optical comb width is 0.25 mm 0.25 ), the transmitted image clarity (C) of the optical comb with a width of 0.5 mm 0.5 ), the transmitted image clarity (C) of the optical comb width is 1.0 mm 1.0 ), the transmitted image clarity (C) of the optical comb width is 2.0 mm 2.0 ) was measured. Also, C 0.125 , C 0.5 , C 1.0 and C 2.0 The sum of the four transmission clarity values ​​was calculated.

[0165] 1-4. 10 cm x 5 cm samples were cut from the optical films of the 60-degree specular gloss examples and comparative examples. The samples were visually inspected to ensure there were no abnormalities such as dust or scratches. The 60-degree specular gloss of each sample was measured with a black plate in close contact with the second surface of the sample using the air suction method. A gloss meter "Model No.: GM-26PRO" manufactured by Murakami Color Technology Research Institute was used to measure the specular gloss. The black plate was an accessory included with the gloss meter. The light incident surface when measuring the specular gloss was the first surface side of the optical film constituting each sample.

[0166] 1-5. Reflectance The reflectance measured by the SCI method and the SCE method were measured from the first surface of the first sample prepared in 1-1. The measuring device used was a spectrophotometer manufactured by Konica Minolta (product name: CM-600d). The measuring device conforms to geometric condition c of JIS Z8722:2009. <Measurement conditions> Main light source: D65 Light source 2: None Field of view: 2 degrees Color system: Yxy Color difference formula: ΔE ＊ ab

[0167] 1-6. Measurement of Surface Shape The optical films of the example and comparative example were cut into 10 cm x 10 cm sections. The cutting locations were selected randomly after visually confirming that there were no abnormalities such as dust or scratches. A second sample was prepared by attaching the substrate side of the cut optical film to a glass plate (thickness 2.0 mm) measuring 10 cm x 10 cm via a transparent optical adhesive sheet from Panac Co., Ltd. (product name: Panaclean PD-S1, thickness 25 μm). The second sample was set on the measurement stage using a white light interference microscope (New View 7300, Zygo Co., Ltd.) so that it was fixed and in close contact with the surface. Next, the surface shape of the first surface of the second sample was measured and analyzed under the following conditions. The measurement and analysis software used was the Microscope Application of MetroPro ver 9.0.10 (64-bit).

[0168] (Measurement conditions) ・Objective lens: 50x ・ImageZoom: 1x ・Measurement area: 218μm x 218μm ・Resolution (spacing per point): 0.22μm ・Instrument: NewView7000 Id 0 SN 073395 ・Acquisition Mode: Scan ・Scan Type: Bipolar ・Camera Mode: 992x992 48 Hz ・Subtract SysErr: Off ・SysErr File: SysErr. dat ・AGC: Off ・Phase Res: High ・Connection Order: Location ・Discon Action: Filter ・Min Mod (%): 0.01 ・Min Area Size: 7・Remove Fringes: Off ・Number of Averages: 0 ・FDA Noise Threshold: 10 ・Scan Length: 15um bipolar (6 sec) ・Extended Scan Length: 1000 μm ・FDA Res: High 2G

[0169] (Analysis conditions) ・Removed: None ・Data Fill: On ・Data Fill Max: 10000 ・Filter: HighPass ・Filter Type: GaussSpline ・Filter Window Size: 3 ・Filter Trim: Off ・Filter Low wavelength: 800 μm ・Min Area Size: 0 ・Remove spikes: On ・Spike Height (xRMS): 2.5 Note that Low wavelength corresponds to the cutoff value λc in the roughness parameter.

[0170] Next, the "Save Data" button was displayed on the Surface Map screen to save the 3D surface roughness data after analysis. Then, the saved data was loaded into the Advanced Texture Application and the following analysis conditions were applied. (Analysis conditions) - High FFT Filter: off - Low FFT Filter: off - Calc High Frequency: On - Calc Low Frequency: On - Filter Trim: On・Remove spikes: Off ・Spike Height (xRMS): 5.00 ・Noise Filter Size: 0 ・Noise Filter Type: 2 Sigma ・Fill Data: Off ・Data Fill Max: 25 ・Trim: 0 ・Trim Mode: All ・Remove: Plane ・Reference Band: 0 μm ・Mim Peaks / Valleys Area: 0 μm ２ ・Max Peaks / Valleys Area: 0μm ２

[0171] Next, in the Advanced Texture Application, "Peaks / Valleys" was selected to display the "Peaks / Valleys" screen. On the "Peaks / Valleys" screen, "Peaks Stats" was selected to display the Height and Slope values ​​for each peak. The multiple Height values ​​displayed on the screen correspond to the maximum height (Hmax) within one peak region of j2 in the specification text. The multiple Slope values ​​displayed on the screen correspond to the Slope within one peak region of k2 in the specification text. Based on these displayed values, the mean Height, standard deviation of Height, mean Slope, and standard deviation of Slope for one measurement location were calculated. The same procedure was performed at 15 locations, and the mean height, standard deviation of height, mean slope, and standard deviation of slope were calculated for 16 locations. Then, the average of the 14 locations, excluding the maximum and minimum values, was used as the mean height, standard deviation of height, mean slope, and standard deviation of slope for each example and comparative example.

[0172] 1-7. The optical films of the anti-glare examples and comparative examples were cut into 10 cm x 10 cm sections. The cutting locations were selected randomly after visual inspection to ensure there were no abnormalities such as dust or scratches. A third sample was prepared by attaching the substrate side of the cut optical film to a 10 cm x 10 cm black board (Kuraray Co., Ltd., product name: Comoglass DFA2CG 502K (black) series, thickness 2 mm) via a Panac Co., Ltd. optical transparent adhesive sheet (product name: Panaclean PD-S1, thickness 25 μm). In a brightly lit room, the third sample was placed on a horizontal stand 70 cm high with the uneven surface facing upwards. The sample was positioned so that it was approximately directly below the illumination light. The sample was observed from the front (however, the observer was not obstructed by the illumination light), and the reflection of the illumination light onto the uneven surface was evaluated according to the following evaluation criteria. The lighting used was an Hf32 type straight tube tri-wavelength daylight white fluorescent lamp, positioned 2m vertically above the horizontal platform. The illuminance on the uneven surface of the sample was evaluated within the range of 500 lux to 1000 lux. The observer's line of sight was approximately 120cm from the floor. The observer was a healthy person in their 30s with visual acuity of 0.7 or better. <Evaluation Criteria> A: No outline of the light source, and its position is not discernible B: No outline of the light source, but its position is vaguely discernible B-: Both the outline and position of the light source are vaguely discernible C: The outline of the light source is not very blurred, and its position is clearly discernible

[0173] 1-8. The substrate side of the optical films of the color examples and comparative examples was fixed to the surface of an image display device via a transparent optical adhesive sheet from Panac Corporation (product name: Panaclean PD-S1, thickness 25 μm). The image display device used was an Apple iPad® Pro 6th generation 12.9-inch size. The image display device was held in the hand, and the color was observed from all angles from +60 degrees to -60 degrees, with the normal direction of the image display device as the reference, in a bright room environment with an illuminance of 500 lux to 1000 lux. The distance between the observer's eye and the display surface of the image display device was approximately 50 cm. The color was observed at a position where the lighting was reflected on the surface of the image display device. Thirty healthy subjects observed the color in two states: with the screen displaying black and with the screen displaying white, and evaluated according to the following criteria. <Evaluation Criteria> A: Fewer than 5 people answered that the color was bothersome in either the black display or the white display. B: Six to fifteen people answered that they were concerned about the color of either the black or white display. C: Sixteen to twenty-five people answered that they were concerned about the color of either the black or white display. D: Twenty-six or more people answered that they were concerned about the color of either the black or white display.

[0174] 1-9. Visibility of Seams Four 7cm x 7cm squares were cut from the optical films of the examples and comparative examples at random positions. The substrate side of the cut optical films was fixed to the surface of the image display device without gaps, in a 2x2 arrangement, using Panac's optical transparent adhesive sheet (product name: Panaclean PD-S1, thickness 25μm). The image display device used was an Apple iPad® Pro 6th generation 12.9-inch model. The image display device was held in the hand, and the color was observed from all angles from +60° to -60° relative to the normal direction of the image display device in a bright room environment with an illuminance of 500 lux to 1000 lux. The distance between the observer's eye and the display surface of the image display device was approximately 50 cm. Thirty healthy subjects evaluated the visibility of the seams of the optical films in two states: with the screen displaying black and with the screen displaying white. The evaluation point was whether or not the boundary line between adjacent optical films was visible as a line. <Evaluation Criteria> A: Fewer than 5 people answered that they were concerned about the boundary line in either the black or white area. B: 6 to 15 people answered that they were concerned about the boundary line in either the black or white area. C: 16 to 25 people answered that they were concerned about the boundary line in either the black or white area. D: 26 or more people answered that they were concerned about the boundary line in either the black or white area.

[0175] 1-10. Overall Evaluation of Color and Seam Visibility An overall evaluation of color and seam visibility was conducted according to the following criteria. <Evaluation Criteria> AA: Both evaluations are A. A: One of the two evaluations is A and the other is B. B: Both of the two evaluations are B. C: At least one of the two evaluations is C or D.

[0176] 1-11. The optical films of the examples and comparative examples of whitishness were fixed to the surface of an image display device. The image display device used was an Apple iPad® Pro 6th generation 12.9-inch size. The image display device was held in the hand, and the whitishness was observed from the normal direction of the image display device in a bright room environment with an illuminance of 500 lux to 1000 lux. The distance between the observer's eye and the display surface of the image display device was approximately 50 cm. The whitishness was observed at a position where the lighting was not reflected on the surface of the image display device. Thirty healthy subjects observed the color in two states: with the screen displaying black and with the screen displaying green, and evaluated according to the following criteria. <Evaluation Criteria> A: Fewer than 5 people answered that the whiteness of the screen was noticeable in either the black display or the green display. B: Six to 15 people answered that the whiteness of the screen was noticeable in either the black display or the green display. － : 16 to 20 people answered that they were bothered by the whiteness of the screen when either black or green was displayed. C: 21 or more people answered that they were bothered by the whiteness of the screen when either black or green was displayed.

[0177] 2. Preparation of Optical Films [Example 1] A coating solution for the anti-glare layer with the composition shown in Table 1 was applied to a substrate (triacetylcellulose resin film with a thickness of 80 μm, Fujifilm Corporation). Then, it was dried at 50°C and a wind speed of 2 m / s for 40 seconds, and then dried again at 70°C and a wind speed of 15 m / s for 45 seconds. Next, the integrated light intensity was set to 50 mJ / cm² under a nitrogen atmosphere with an oxygen concentration of 200 ppm or less. ２ A 6.0 μm thick anti-glare layer was formed by irradiating it with ultraviolet light to achieve the desired result. Next, a low refractive index coating solution with the composition shown in Table 2 was applied to the anti-glare layer. Then, it was dried at 40°C and a wind speed of 20 m / s for 15 seconds, and further dried at 70°C and a wind speed of 15 m / s for 30 seconds. Finally, it was subjected to an integrated light intensity of 150 mJ / cm² in a nitrogen atmosphere with an oxygen concentration of 200 ppm or less. ２ By irradiating with ultraviolet light in such a manner, a low refractive index layer with a thickness of 0.10 μm was formed, and the optical film of Example 1 was obtained.

[0178] [Examples 2-7], [Comparative Examples 1-5] Optical films of Examples 2-7 and Comparative Examples 1-5 were obtained in the same manner as in Example 1, except that the composition of the coating solution for the anti-glare layer, the thickness of the anti-glare layer, and the composition of the coating solution for the low refractive index layer were changed to the conditions shown in Tables 1 and 2.

[0179] [Comparative Example 6] A coating solution for an anti-glare layer with the composition shown in Table 1 was applied to a substrate (triacetylcellulose resin film with a thickness of 80 μm, Fujifilm Corporation). It was then dried at 50°C and a wind speed of 5 m / s for 30 seconds, and further dried at 70°C and a wind speed of 10 m / s for 45 seconds. Finally, the integrated light intensity was measured at 50 mJ / cm² under a nitrogen atmosphere with an oxygen concentration of 200 ppm or less. ２ A 4.8 μm thick anti-glare layer was formed by irradiating it with ultraviolet light to achieve the desired result. Next, a low refractive index coating solution with the composition shown in Table 2 was applied to the anti-glare layer. Then, it was dried at 50°C and a wind speed of 20 m / s for 30 seconds. Next, it was dried in a nitrogen atmosphere with an oxygen concentration of 200 ppm or less until the integrated light intensity reached 150 mJ / cm². ２ By irradiating with ultraviolet light in such a manner, a low refractive index layer with a thickness of 0.10 μm was formed, and the optical film of Comparative Example 6 was obtained.

[0180]

[0181] The materials for the anti-glare coating liquid in Table 1 are as follows: • Silica particles A (surface-treated amorphous silica, d10: 0.8 μm, d50: 2.8 μm, d90: 4.5 μm) • Silica particles B (surface-treated amorphous silica, d10: 1.6 μm, d50: 3.7 μm, d90: 6.2 μm) • Silica particles C (surface-treated amorphous silica, d10: 2.3 μm, d50: 5.1 μm, d90: 7.4 μm) • Silica particles D (surface-treated amorphous silica, d10: 1.0 μm, d50: 3.0 μm, d90: 4.8 μm) • Silica particles E (surface-treated amorphous silica, d10: 1.3 μm, d50: 2.8 μm, d90: 4.8 μm) • Organic particles A • Organic particle B (Spherical polyacrylic-styrene copolymer, average particle size 1.5 μm, refractive index 1.515) • Organic particle C (Spherical polyacrylic-styrene copolymer, average particle size 1.5 μm, refractive index 1.59) • Organic particle D (Spherical polyacrylic-styrene copolymer, average particle size 3.0 μm, refractive index 1.59) • Inorganic ultrafine particles (Silica with average primary particle size of 10 nm) • DPHA (Dipentaerythritol hexaacrylate, Nippon Kayaku Co., Ltd., product name: KAYARAD DPHA) • PETA (Pentaerythritol triacrylate, Toagosei Co., Ltd., product name: M-305) • Urethane acrylate oligomer A (Mitsubishi Chemical Corporation, product name: UV-6300B: weight-average molecular weight 3,700, number of functional groups 7) ・Urethane acrylate oligomer B (Shin Nakamura Chemical Industry Co., Ltd., product name: UA-33H: weight-average molecular weight 1,400, number of functional groups 9) ・Urethane acrylate oligomer C (Shin Nakamura Chemical Industry Co., Ltd., product name: U-15HA: weight-average molecular weight 2,300, number of functional groups 15) ・Urethane acrylate oligomer D (Mitsubishi Chemical Corporation, product name: UV-1700B: weight-average molecular weight 2,000, 10 functional groups) ・Urethane acrylate oligomer E (Shin Nakamura Chemical Industry Co., Ltd., product name: UA-1100H: weight-average molecular weight 800, 6 functional groups) ・Photopolymerization initiator A (IGM Resins B.V., product name: Omnirad 184) ・Photopolymerization initiator B (IGM Resins B.V., product name: Omnirad 907) ・Leveling agent (silicone-based leveling agent, Momentive Performance Materials, product name: TSF4460),

[0182]

[0183] The materials for the coating solution for the low refractive index layer in Table 2 are as follows: • Polyfunctional acrylate A (manufactured by Toagosei Co., Ltd., product name "Aronics M-400") • Polyfunctional acrylate B (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name "New Frontier MF-001") • Thermoplastic resin A (acrylic polymer, weight-average molecular weight: 40,000) • Thermoplastic resin B (acrylic polymer, weight-average molecular weight: 50,000) • Hollow silica particles A (average primary particle diameter 75 nm, particles surface-treated with a silane coupling agent having methacryloyl groups) • Hollow silica particles B (average primary particle diameter 100 nm, particles surface-treated with a silane coupling agent having methacryloyl groups) • Solid silica particles A (average primary particle diameter 13 nm, particles surface-treated with a silane coupling agent having methacryloyl groups) • Solid silica particles B (average primary particle diameter 12.5 nm, particles surface-treated with a silane coupling agent having methacryloyl groups) • Leveling agent A (Fluorine-based leveling agent) (Daikin Corporation, product name "Optoul DAC-200", solids content: 20%, solvent: 1-methoxy-2-propyl acetate, methyl ethyl ketone) (Note: The amount of leveling agent in Table 2 is converted to solids content.) • Leveling agent B (Fluorosilicone-based leveling agent) (Shin-Etsu Chemical Co., Ltd., product name "KY-1203", solids content: 20%, solvent: methyl isobutyl ketone) (Note: The amount of leveling agent in Table 2 is converted to solids content.) • Leveling agent C (Silicone-based leveling agent) (Shin-Etsu Chemical Co., Ltd., product name "X-22-164E") • Photopolymerization initiator C (IGM Resins B.V., product name: Omnirad127)

[0184]

[0185]

[0186]

[0187] The results in Tables 3-5 confirm that the optical film of the example can suppress variations in color depending on the viewing angle and the visibility of seams or other lines within the image.

[0188] 10: Substrate 20: Anti-glare layer 30: Anti-reflective layer 100: Optical film 110: Display element 120: Image display panel 200: Adhesive layer 300: Black board 400: First sample 500: Variable angle spectrophotometer 501: Light source 502: Photodetector S1: First surface S2: Second surface

Claims

1. An optical film having a first surface and a second surface which is a surface opposite to the first surface, wherein the optical film has an antireflection layer and an antiglare layer in this order from the first surface toward the second surface, the first surface has an uneven shape, and the maximum value of six Δab calculated by the following Formula 1 is 0.20 or more and 2.50 or less.<Formula 1>Δab = {(a ＊ −a ｎ＋１ ) ２ + (b ｎ −b ｎ＋１ ) ２} １／２ (In Formula 1, a ｎ represents the a of the Lab color system calculated from the reflected light in the n-th measurement direction in the first measurement described below ＊ value, a ｎ＋１ represents the a of the Lab color system calculated from the reflected light in the (n+1)-th measurement direction in the first measurement described below ＊ value, b ｎ represents the b of the Lab color system calculated from the reflected light in the n-th measurement direction in the first measurement described below ＊ value, b ｎ＋１ represents the b of the Lab color system calculated from the reflected light in the (n+1)-th measurement direction in the first measurement described below ＊ value. In Formula 1, n represents an integer of 1 or more and 6 or less.)<First Measurement>A first sample is produced by bonding a black plate to the surface on the second surface side of the optical film via an adhesive layer. One surface of the first sample is the first surface of the optical film. The normal direction of the first surface of the first sample is defined as 0 degrees. Using a variable-angle spectrophotometer, parallel light is irradiated from the +45 degree direction on the first surface side of the first sample, and the reflected light of the parallel light is measured in seven directions of -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -55 degrees, and -60 degrees respectively. With -30 degrees as the first measurement direction and -60 degrees as the seventh measurement direction, L of the Lab color system is obtained from the reflected light in each of the first to seventh measurement directions ＊ value, a ＊ value and b ＊ value are calculated.

2. The optical film according to claim 1, wherein the minimum value of the six Δab calculated by formula 1 is 0.02 or more and 0.50 or less.

3. In the first measurement, the a of the Lab color system calculated from the reflected light in the first to seventh measurement directions, respectively. ＊ The maximum value of a ＊ MAX and a ＊ a is the minimum value of the value. ＊ The optical film according to claim 1, wherein the absolute value of the difference from MIN is 0.25 or more and 3.00 or less.

4. In the first measurement, the b of the Lab color system calculated from the reflected light in the first to seventh measurement directions. ＊ The maximum value is b ＊ MAX and b ＊ The minimum value of b ＊ The optical film according to claim 1, wherein the absolute value of the difference from MIN is 0.30 or more and 3.50 or less.

5. In the first measurement, the L of the Lab color system calculated from the reflected light in the first to seventh measurement directions, respectively. ＊ The maximum value is L ＊ The optical film according to claim 1, wherein the product of MAX and the haze of the optical film according to JIS K7136:2000 is 850 or less.

6. The optical film according to claim 1, wherein ΔEab in the following formula 2 is 4.80 or more and 20.00 or less. 《Formula 2》 ΔEab = {(L ５ -L ６０ ) ２ + (a ５ -a ６０ ) ２ + (b ５ -b ６０ ) ２ } １／２ (However, in Equation 2, L ５ a ５ , b ５ , L ６０ a ６０ and b ６０ This refers to the value obtained in the second measurement described below.) <Second Measurement> The normal direction of the first surface of the first sample is set to 0 degrees. Using a bending spectrophotometer, parallel light rays are shone onto the first sample from a direction of +5 degrees on the first surface side, and the reflected light of the parallel light rays is measured at a direction of -5 degrees. The L of the Lab color system is calculated from the measured reflected light at -5 degrees. ＊ Value, a ＊ Value and b ＊ The values ​​are L ５ a ５ , b ５ The first sample is irradiated with parallel light rays from the +60-degree direction on the first surface side using the bending angle spectrophotometer, and the reflected light of the parallel rays is measured in the -60-degree direction. The L of the Lab color system is calculated from the measured reflected light at -60 degrees. ＊ Value, a ＊ Value and b ＊ The values ​​are L ６０ a ６０ and b ６０ Let's assume that.

7. The optical film according to claim 1, wherein the haze according to JIS K7136:2000 is 20% or more and 75% or less.

8. The optical film according to claim 1, wherein a sample for gloss measurement is prepared by adhering a black plate to the second surface side of the optical film by air suction, and the 60-degree specular gloss measured from the first surface side of the sample is 5.0% or more and 80.0% or less.

9. The optical film according to claim 1, wherein the reflectance measured by the SCI method from the first surface side of the first sample is 0.30% or more and 3.00% or less.

10. The optical film according to claim 1, wherein the reflectance measured by the SCE method from the first surface side of the first sample is 0.15% or more and 2.00% or less.

11. The optical film according to claim 1, wherein the first surface has a height average of 0.03 μm or more and a height coefficient of variation of 0.50 or more.

12. The optical film according to claim 1, wherein the first surface has a slope average of 25.0 μm / mm or more and a slope coefficient of variation of 0.30 or more.

13. The optical film according to claim 1, wherein the anti-glare layer comprises a binder component and particles.

14. The optical film according to claim 1, further comprising a substrate, wherein the anti-reflective layer, the anti-glare layer, and the substrate are arranged in this order from the first surface to the second surface.

15. A polarizing plate having a polarizer, a first transparent protective plate disposed on one side of the polarizer, and a second transparent protective plate disposed on the other side of the polarizer, wherein at least one of the first transparent protective plate and the second transparent protective plate is the optical film described in claim 1, and the second surface of the optical film and the polarizer are disposed opposite each other.

16. A surface plate for an image display device, comprising a protective film laminated onto a resin plate or a glass plate, wherein the protective film is the optical film described in claim 1, and the second surface of the optical film and the resin plate or glass plate are arranged facing each other.

17. An image display panel having a display element and an optical film disposed on the light-emitting surface side of the display element, wherein the optical film includes the optical film described in claim 1.

18. The image display panel according to claim 17, wherein the display element is a micro LED display element.

19. An image display device comprising the image display panel described in claim 17 or 18.

Images