JP6484847B2 - Touch panel, display device, optical sheet, optical sheet sorting method, and optical sheet manufacturing method - Google Patents

Description

  The present invention relates to a touch panel, a display device, an optical sheet, an optical sheet sorting method, and an optical sheet manufacturing method.

In recent years, mobile information terminal devices equipped with a transparent touch panel for information display and information input, which have bidirectional communication functions such as tablet PCs and smartphones, have begun to spread widely not only in Japan but around the world. Came.
A transparent touch panel has a resistive film method that is excellent in terms of cost, but it has electrostatic capacity in that gesture operations such as multi-touch are possible, and it is difficult to impair the image quality of ultra-high-definition display elements. There is an increasing demand for touch panel touch panels, particularly projection capacitive touch panels.

An anti-glare sheet having a concavo-convex structure may be provided on the surface of the touch panel for the purpose of preventing reflection of external light.
Furthermore, for the prevention of adhesion and interference fringes between members constituting the touch panel, and prevention of adhesion and interference fringes between the touch panel and the display element, the outermost surface base material, the inner base material and the rearmost surface of the touch panel An optical sheet having a concavo-convex structure may be used as a substrate or the like.

However, when an optical sheet having a concavo-convex structure such as an antiglare film is used, a phenomenon (glare) in which minute variations in luminance are seen in the image light occurs due to the concavo-convex structure, which reduces display quality. There's a problem. In particular, glare tends to increase in recent ultra-high-definition display elements (pixel density of 300 ppi or more), and the problem of glare is becoming more serious.
As techniques for preventing glare due to surface irregularities, techniques of Patent Documents 1 to 9 have been proposed.

Japanese Patent Laid-Open No. 11-305010 JP 2002-267818 A JP 2009-288650 A JP 2009-86410 A JP 2009-128393 A JP 2002-196117 A International Patent Publication No. 2007/11126 JP 2008-158536 A JP 2011-253106 A

Patent documents 1 and 2 improve glare by giving internal haze. However, an ultra-high-definition display element with a pixel density of 300 ppi or more tends to be more glaring. If an attempt is made to suppress the glaring only by the internal noise, the internal noise must be further increased. Also, when the internal haze is large, the resolution tends to deteriorate, but this tendency is greater in the ultra-high definition display element. Therefore, Patent Documents 1 and 2 cannot simultaneously prevent glare and a decrease in resolution in an ultrahigh-definition display element having a pixel density of 300 ppi or more.
Patent Documents 3 to 9 provide anti-glare properties and improve glare by designing the surface shape of the optical sheet into a specific shape. However, even the techniques of Patent Documents 3 to 9 cannot prevent glare in an ultra-high-definition display element having a pixel density of 300 ppi or more.

  The present invention has been made under such circumstances, and even in the case of having an uneven structure, it is possible to prevent glare of image light of an ultra-high-definition display element having a pixel density of 300 ppi or more and to prevent a reduction in resolution. An object of the present invention is to provide a touch panel, a display device, and an optical sheet that can be used. It is another object of the present invention to provide an optical sheet selection method and manufacturing method that can prevent a decrease in resolution while preventing glare of image light from an ultra-high-definition display element having a pixel density of 300 ppi or more.

In order to solve the above-described problems, the present inventors have intensively studied an optical sheet that prevents glare. First, it is considered that the glare is caused by distortion of the transmitted light due to the uneven shape when the image light passes through the optical sheet having surface unevenness. For this reason, conventionally, in order to prevent glare, as in Patent Documents 3 to 9, a design to increase the smooth surface by reducing the inclination angle of the unevenness (design to reduce the degree of unevenness) has been performed.
However, as described above, in a design that reduces the degree of unevenness, even if it was possible to prevent glare of a display element having a low pixel density, glare of an ultra-high-definition display element having a pixel density of 300 ppi or more could not be prevented. In addition, in recent years, portable information terminals represented by smartphones are required to have high anti-glare properties because touch panel operations are performed outdoors. However, in a design that prevents glare by increasing the proportion of smooth surfaces, It was not possible to satisfy the high antiglare property.
Further, as described above, it is not possible to simultaneously prevent glare and a decrease in resolution of an ultra-high-definition display element having a pixel density of 300 ppi or more only by giving a noise to the inside.
As a result of diligent research, the present inventors have found that glare is caused by local unevenness such as luminance due to the relationship between pixel density and uneven shape, and that internal noise is a role that makes glare difficult to see due to diffusion. The knowledge that it has was acquired. And, as a result of earnest research on preventing glare without relying on internal noise that may lead to a decrease in resolution, the present inventors have obtained a formula (I), which will be described later, indicating the ratio of surface irregularities, and It has been found that by setting the surface haze indicating a region having an inclination angle of 5 degrees or more to a specific range, it is possible to prevent glare and to prevent the resolution of the ultra-high-definition display element from being lowered, and the present invention has been completed. .

That is, the present invention provides the following touch panel, display device, and optical sheet of [1] to [11], an optical sheet selection method, and an optical sheet manufacturing method.
[1] A touch panel having an optical sheet as a constituent member, the optical sheet having an uneven shape on one surface, having a surface haze of 22 to 40%, and the unevenness of the optical sheet. Irradiate visible light perpendicularly to the optical sheet from the surface direction opposite to the surface having the shape, and measure the intensity of a certain angle range from the surface side having the concavo-convex shape with respect to the transmitted light. The line connecting the intensity at +2 degrees and the intensity at +1 degree extrapolated to the normal transmission angle, and the line connecting the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction A touch panel used on the front surface of a display element having a pixel density of 300 ppi or more that satisfies the relationship of the following formula (I) when the average value of the intensity extrapolated to the normal transmission angle is “virtual intensity in the normal transmission direction” .
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)
[2] The touch panel according to [1], in which a diffusion angle indicating a luminance of ½ of the virtual intensity in the regular transmission direction is “α”, and an absolute value of α is 1.4 to 3.0 degrees.
[3] Described in [1] or [2], in which a diffusion angle indicating a luminance of 1/3 of the virtual intensity in the regular transmission direction is “β”, and an absolute value of β is 1.9 to 5.0 degrees. Touch panel.
[4] In the above [1] to [3], a diffusion angle indicating a luminance of 1/10 of the virtual intensity in the regular transmission direction is “γ”, and an absolute value of γ is 3.5 to 8.0 degrees. The touch panel as described in any one.
[5] A display device having an optical sheet on the front surface of a display element having a pixel density of 300 ppi or more, wherein the optical sheet has a concavo-convex shape on one surface and has an internal noise of 5 to 30. %, And visible light is irradiated perpendicularly to the optical sheet from a surface direction opposite to the surface having the concavo-convex shape of the optical sheet. The intensity obtained by extrapolating the straight line connecting the intensity at +2 degrees and the intensity at +1 degree with respect to the normal transmission direction to the normal transmission angle and the intensity at -2 degrees with respect to the normal transmission direction A display device that satisfies the relationship of the following formula (I) when the average value of the intensity obtained by extrapolating the straight line connecting the intensity at -1 degree to the normal transmission angle is “virtual intensity in the normal transmission direction” .
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)

[6] An optical sheet having a concavo-convex shape on one surface, the optical sheet having a surface haze of 22 to 40%, and a surface opposite to the surface having the concavo-convex shape of the optical sheet Irradiate visible light perpendicularly to the optical sheet from the direction, and measure the intensity of a certain angle range from the surface side having the concavo-convex shape with respect to the transmitted light. The intensity obtained by extrapolating the straight line connecting the intensity of the light to the normal transmission angle, and the intensity extrapolating the straight line connecting the intensity at -2 degrees and the intensity at -1 degree to the normal transmission angle An optical sheet used on the front surface of a display element having a pixel density of 300 ppi or more, satisfying the relationship of the following formula (I), when the average value is “virtual intensity in the normal transmission direction”.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)
[7] The optical sheet according to the above [6], wherein a diffusion angle indicating half the virtual intensity in the regular transmission direction is “α”, and an absolute value of α is 1.4 to 3.0 degrees. .
[8] In the above [6] or [7], a diffusion angle indicating an intensity of 1/3 of the virtual intensity in the normal transmission direction is “β”, and an absolute value of β is 1.9 to 5.0 degrees. The optical sheet described.
[9] The diffusion angle indicating the intensity of 1/10 of the virtual intensity in the regular transmission direction is “γ”, and the absolute value of γ is 3.5 to 8.0 degrees above [6] to [8] The optical sheet according to any one of the above.

[10] A method for selecting an optical sheet having a concavo-convex shape on one surface, wherein (a) the surface haze of the optical sheet satisfies 22 to 40%, and (b) the concavo-convex shape of the optical sheet is provided. The optical sheet is irradiated with visible light perpendicularly from the surface direction opposite to the surface, and the intensity of a certain angle range is measured from the surface side having the concavo-convex shape with respect to the transmitted light, and +2 degrees with respect to the normal transmission direction The straight line connecting the intensity connecting the intensity at +1 degree and the intensity at +1 degree to the normal transmission angle, and the straight line connecting the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction. When the average value with the intensity extrapolated to the angle is set as the “virtual intensity in the normal transmission direction”, the one satisfying the following formula (I) is selected as an optical sheet and used for the front surface of a display element having a pixel density of 300 ppi or more. Optical sheet sorting method.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)
[11] A method for producing an optical sheet having a concavo-convex shape on one surface, wherein (a) the surface haze of the optical sheet satisfies 22 to 40%, and (b) the concavo-convex shape of the optical sheet is provided. The optical sheet is irradiated with visible light perpendicularly from the surface direction opposite to the surface, and the intensity of a certain angle range is measured from the surface side having the concavo-convex shape with respect to the transmitted light, and +2 degrees with respect to the normal transmission direction The straight line connecting the intensity connecting the intensity at +1 degree and the intensity at +1 degree to the normal transmission angle, and the straight line connecting the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction. An optical sheet used for the front surface of a display element having a pixel density of 300 ppi or more, manufactured so as to satisfy the following formula (I) when the average value of the intensity extrapolated to the angle is set to “virtual intensity in the normal transmission direction” Manufacturing method.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)

The touch panel, display device, and optical sheet of the present invention can prevent glare of an ultra-high-definition display element having a pixel density of 300 ppi or more while imparting various characteristics such as anti-glare properties, and further, the resolution of the ultra-high-definition display element. Can be prevented. In particular, when the uneven surface of the optical sheet is used facing the viewer side, reflection of external light can be suppressed even in a bright outdoor environment, and high antiglare properties can be imparted.
In addition, the optical sheet evaluation method of the present invention can guarantee the performance of preventing a decrease in resolution while preventing glare without incorporating an optical sheet in a display device, and efficiently controls the quality of the optical sheet. it can. In addition, the optical sheet manufacturing method of the present invention can efficiently manufacture an optical sheet that can prevent glare of image light without reducing the resolution of an ultra-high-definition display element having a pixel density of 300 ppi or more.

It is sectional drawing which shows one Embodiment of the resistive film type touch panel of this invention. It is sectional drawing which shows one Embodiment of the capacitive touch panel of this invention. FIG. 4 is a diagram illustrating an intensity distribution of transmitted light of the optical sheet of Example 1. FIG. 6 is a diagram illustrating an intensity distribution of transmitted light of the optical sheet of Example 2. FIG. 6 is a diagram showing an intensity distribution of transmitted light of the optical sheet of Example 3. 6 is a diagram illustrating an intensity distribution of transmitted light of an optical sheet of Comparative Example 1. FIG. It is a figure which shows intensity distribution of the transmitted light of the optical sheet of the comparative example 2. It is a figure which shows intensity distribution of the transmitted light of the optical sheet of the comparative example 3. It is a figure which shows intensity distribution of the transmitted light of the optical sheet of the comparative example 4. 2 is a scanning transmission electron micrograph (STEM) showing a cross section of the optical sheet of Example 1. FIG.

Embodiments of the present invention will be described below.
[Touch panel]
The touch panel of the present invention is a touch panel having an optical sheet as a constituent member, and the optical sheet has an uneven shape on one surface, the surface haze is 22 to 40%, and the optical Irradiate visible light perpendicularly to the optical sheet from the surface direction opposite to the surface having the uneven shape of the sheet, and measure the intensity of a certain angle range from the surface side having the uneven shape with respect to the transmitted light. An intensity obtained by extrapolating a straight line connecting the intensity at +2 degrees and the intensity at +1 degree to the normal transmission angle, an intensity at -2 degrees and an intensity at -1 degree with respect to the normal transmission direction When the average value of the intensity obtained by extrapolating the straight line connecting to the normal transmission angle is “virtual intensity in the normal transmission direction”, the relationship of the following formula (I) is satisfied, and the pixel density is 300 ppi or more on the front surface of the display element. It is used.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)

Examples of the touch panel include a capacitive touch panel, a resistive touch panel, an optical touch panel, an ultrasonic touch panel, and an electromagnetic induction touch panel. These touch panels have a base material such as a glass base material and a plastic film base material, and the surface on the base material has an uneven shape for imparting various characteristics such as antiglare property, adhesion prevention and interference fringe prevention. May be formed. The touch panel of the present invention uses an optical sheet to be described later as a substrate having an uneven shape on such a surface.
In addition, the optical sheet described later can impart good anti-glare properties even in a bright environment outdoors, and can also prevent glare and a decrease in resolution. Therefore, the touch panel of the present invention is preferably used so that the uneven surface of the optical sheet described later faces the operator side (the side opposite to the display element). A portable information terminal typified by a smartphone in recent years has an ultra-high-definition display element and performs a touch panel operation outdoors, so that the uneven surface of an optical sheet, which will be described later, faces the operator side. Is very useful.

  As shown in FIG. 1, the resistive touch panel has a basic configuration in which a conductive film 12 of a pair of upper and lower transparent substrates 11 having a conductive film 12 is arranged through a spacer 13 so as to face each other. A circuit that is not connected is connected. In the case of a resistive film type touch panel, it is preferable to use an optical sheet described later as the upper transparent substrate and / or the lower transparent substrate. In addition, the upper transparent substrate and the lower transparent substrate may use an optical sheet described later as one base material as a multilayer structure including two or more base materials.

The optical sheet in the resistive film type touch panel, for example, uses an optical sheet, which will be described later, as the upper transparent substrate, and if the concave and convex surface of the optical sheet faces away from the lower transparent substrate, it is highly advanced in the resistive film type touch panel. Anti-glare properties can be imparted, glare of an ultra-high-definition display element can be prevented, and further, a decrease in resolution of the ultra-high-definition display element can be prevented. In addition, this method is preferable in that it can make it difficult to see the scratches on the surface of the touch panel, the conductive film, etc., and can contribute to the improvement of the yield.
In addition, by using an optical sheet, which will be described later, as the lower transparent substrate of the resistive touch panel, and by making the uneven surface of the optical sheet face the upper transparent substrate side, the reflection of the surface of the lower electrode is suppressed, and the The glare of the fine display element can be prevented. Further, in the case of this usage, it is possible to prevent the upper and lower conductive films from adhering to each other at the time of operation, and it is possible to prevent the occurrence of interference fringes due to the proximity of the upper and lower conductive films.
In addition, when an optical sheet described later is used as the upper transparent substrate and / or the lower transparent substrate so that the concavo-convex surface faces the side opposite to the upper electrode, it is preferable in that adhesion and interference fringes can be prevented.

The capacitive touch panel includes a surface type and a projection type, and a projection type is often used. A projected capacitive touch panel is formed by connecting a circuit to a basic configuration in which an X-axis electrode and a Y-axis electrode orthogonal to the X electrode are arranged via an insulator. The basic structure will be described more specifically. A mode in which X electrodes and Y electrodes are formed on separate surfaces of a single transparent substrate, and an X electrode, an insulator layer, and a Y electrode are formed in this order on the transparent substrate. As shown in FIG. 2, an X electrode 22 is formed on a transparent substrate 21, a Y electrode 23 is formed on another transparent substrate 21, and the layers are laminated via an adhesive layer 24 or the like. It is done. Moreover, the aspect which laminate | stacks another transparent substrate in these basic aspects is mentioned.
In the case of a capacitive touch panel, it is preferable to use an optical sheet described later for at least one of the transparent substrates. In addition, the transparent substrate may use an optical sheet to be described later as one base material as a multilayer structure including two or more base materials.

In the case where the capacitive touch panel has another transparent substrate on the basic aspect described above, an optical sheet to be described later is used as the other transparent substrate, and the uneven surface of the optical sheet is opposite to the basic aspect side. When the concave-convex surface is directed to the operator side, it is possible to impart a high degree of antiglare to the capacitive touch panel and to prevent glare of the ultra-high-definition display element. Further, it is possible to prevent a decrease in resolution of the ultra-high definition display element. In addition, this usage is preferable in that it is difficult to see the scratches on the surface of the touch panel, the conductive film, and the like, and the shape of the electrode pattern.
Further, in the case where the capacitive touch panel has a configuration in which an X electrode is formed on a transparent substrate, a Y electrode is formed on another transparent substrate, and laminated via an adhesive or the like, it will be described later as at least one transparent substrate. The same effect as described above can be obtained even when the optical sheet including the optical sheet is used and the concave / convex surface of the optical sheet faces the side opposite to the basic aspect side and the concave / convex surface is directed to the operator side. Can do.
In addition, when the optical sheet mentioned later is used as a transparent substrate of an electrostatic capacitance type touch panel so that an uneven surface may face the opposite side to an operator, it is suitable at the point which can prevent adhesion and an interference fringe.

(Optical sheet)
The optical sheet used in the touch panel of the present invention has a concavo-convex shape on one surface, the surface haze is 22 to 40%, and the side opposite to the surface having the concavo-convex shape of the optical sheet. Irradiate visible light perpendicularly to the optical sheet from the surface direction, and measure the intensity of a certain angle range from the surface side having the concavo-convex shape for the transmitted light, and the intensity at +2 degrees and +1 degree with respect to the normal transmission direction Intensity obtained by extrapolating the straight line connecting the intensity at the normal transmission angle and extrapolating the straight line connecting the intensity at -2 degrees and the intensity at -1 degree to the normal transmission angle with respect to the normal transmission direction. When the average value is “virtual intensity in the normal transmission direction”, the relationship of the following formula (I) is satisfied.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)

  The optical sheet used for the touch panel of the present invention has a surface haze and a ratio of [intensity in the normal transmission direction / virtual intensity in the normal transmission direction] (hereinafter, sometimes referred to as “intensity ratio”) within a certain range. Accordingly, it is possible to prevent glare of image light of an ultra-high-definition display element having a pixel density of 300 ppi or more and to prevent a decrease in resolution. Even if only one of the surface haze and the intensity ratio satisfies the scope of the present invention, it is impossible to achieve both glare prevention and resolution reduction prevention. Hereinafter, the reason will be described.

First, it is considered that the glare is caused by distortion of the transmitted light due to the uneven shape when the image light passes through the optical sheet having surface unevenness. For this reason, conventionally, in order to prevent glare, a design in which the inclination angle is lowered to reduce the degree of unevenness as in Patent Documents 3 to 9, or a glaze is imparted to the interior as in Patent Documents 1 and 2. Design to reduce the feeling was done.
However, glare of image light of an ultra-high-definition display element having a pixel density of 300 ppi or more cannot be prevented only by a design that weakens the degree of unevenness or only applying noise to the inside.
As a result of diligent research, the present inventors have found that when the inclination angle is lowered and the degree of unevenness is reduced as in the prior art, the ratio of substantially smooth portions that are not uneven increases, and the boundary between the smooth portion and the uneven surface (In other words, a place where a sudden angle change occurs) was found to be a cause of glare. In addition, the JIS standard (JIS B0601) regarding the surface shape stipulates that a contact-type surface shape measuring device is used, but the measurement result cannot accurately reflect the surface shape because of the relationship between the shape of the stylus and the surface shape. There is a case.

Accordingly, the present inventors pay attention to the ratio (intensity ratio) of [intensity in the normal transmission direction / virtual intensity in the normal transmission direction] that indirectly represents the uneven shape, and indirectly in the uneven shape with the intensity ratio being in a certain range. In addition, the surface haze is set within a certain range, and the uneven shape is made more specific, thereby making it possible to prevent a decrease in resolution while preventing glare of an ultra-high-definition display element.
The intensity ratio is approximated to the ratio of light impinging on the diffusing element (the total of the internal diffusing element and the surface diffusing element), which will be described later in detail. In other words, if the intensity ratio is close to 1, it can be said that the ratio of light transmitted through the optical sheet collides with the diffusing element is high, and as the intensity ratio moves away from 1, the ratio of light transmitted through the optical sheet collides with the diffusing element. It can be said that there is little (in other words, “the ratio of light that can be passed through is large”). Also, the effect on the intensity ratio is much greater for the surface diffusing element than for the internal diffusing element. Therefore, the degree of unevenness (surface diffusion element) can be indirectly expressed by defining the intensity ratio.

The optical sheet used in the touch panel of the present invention has an intensity ratio close to 1. For this reason, the optical sheet shows that there are many surface diffusing elements among diffusing elements, in other words, the uneven surface has few surfaces that are almost smooth, and almost the entire surface is uneven. That is, the optical sheet is completely different from the design of the optical sheets of Patent Documents 3 to 9 having many substantially smooth portions.
On the other hand, according to JIS K7136: 2000 and ISO 14782: 1999, the haze is “of the transmitted light passing through the test piece by 0.044 rad (2.5 degrees) or more from the incident light due to forward scattering. It is defined as “percentage”. That is, haze indicates the ratio of scattered light in which incident light is scattered ± 2.5 degrees or more. Further, as a physical property of light, it is known that the angle of light transmitted through the uneven surface is approximately ½ times the tilt angle. In other words, light that passes through a location where the tilt angle exceeds 5 degrees is reflected in haze, but light that passes through a location where the tilt angle is less than 5 degrees is not reflected in haze.
The optical sheet used in the touch panel of the present invention has an intensity ratio close to 1 and almost the entire surface is uneven, but the surface haze is not extremely large. This means that the optical sheet used in the touch panel of the present invention includes many irregularities with a small inclination angle (unevenness with an inclination angle of less than 5 degrees) that are not reflected in the surface haze. Moreover, since the optical sheet used in the touch panel of the present invention does not have a small surface haze, it means that the optical sheet includes many irregularities having a large inclination angle (an irregularity having an inclination angle of 5 degrees or more) reflected in the surface haze.

Since the optical sheet used in the touch panel of the present invention has a substantially smooth surface with an intensity ratio close to 1, and the entire surface is uneven, the boundary between the uneven portion and the substantially smooth portion on the surface of the optical sheet is reduced, It is thought that glare can be easily prevented. Furthermore, since the optical sheet has a surface haze in a range where the intensity ratio is close to 1, and is not too large and not too small, the optical sheet has unevenness with a small inclination angle (unevenness with an inclination angle of less than 5 degrees). ) And unevenness with a large inclination angle (unevenness with an inclination angle of 5 degrees or more) are mixed. As described above, the presence of various inclination angles in the unevenness makes it easier to prevent glare (exactly, it is considered that some glare is also generated in the present invention. It is thought that the glare is averaged and made inconspicuous by reducing the boundary between the uneven part and the substantially smooth part on the surface of the sheet and by making various inclination angles exist.
In addition, since the optical sheet has a substantially smooth surface on the uneven surface and has various inclination angles, it can provide high antiglare properties that can withstand bright outdoor environments. In addition, the optical sheet is substantially uneven on the entire surface, while there are many unevenness with a small inclination angle that is not reflected in haze, so that when the optical sheet is used as an antiglare sheet, the resolution is prevented from decreasing. Therefore, it is possible to prevent a decrease in contrast.

As described above, in the present invention, various characteristics such as anti-glare property are imparted by using an optical sheet having a surface haze of 22 to 40% and an intensity ratio of 1.0 to 4.0. However, it is possible to prevent glare and resolution reduction of the ultra-high definition display element.
If the surface haze is less than 22% or the strength ratio exceeds 4.0, glare cannot be prevented. Further, when the surface haze exceeds 40%, the resolution is lowered.
In addition, when the intensity ratio exceeds 4.0, the ratio of the portion having the diffusing element decreases, and it becomes difficult to provide high antiglare properties that can withstand the bright outdoor environment, and on the surface of the optical sheet. There are many places where an abrupt angle change occurs, and glare tends to occur.
The surface haze is preferably 25 to 40%, more preferably 25 to 35%. The surface haze can be obtained by the method described in Examples.
The intensity ratio is preferably 1.0 or more and 3.5 or less, more preferably 1.0 or more and 2.0 or less, and further preferably 1.0 or more and 1.5 or less.

(Calculation method of ratio of [strength in regular transmission direction / virtual intensity in regular transmission direction])
First, the strength of the optical sheet is measured as follows.
Visible rays (parallel rays) are irradiated perpendicularly to the optical sheet from the surface direction opposite to the surface having the irregular shape of the optical sheet. It is preferable that the surface opposite to the surface having the uneven shape is substantially smooth. When the surface opposite to the surface having the irregular shape is not substantially smooth, a substrate having a substantially smooth surface is bonded via an adhesive layer tape, and visible light is incident on the optical sheet perpendicularly from the substantially smoothed surface direction. And measure the strength. In addition, a substantially smooth surface means that Ra is 0.02 μm or less. Then, with respect to the transmitted light, the light receiver is scanned every 1 degree within a certain angle range from the surface side having the uneven shape, and the intensity (luminous intensity) at each angle is measured. The measurement range may be measured in a range of about ± 20 degrees with the vertical direction being 0 degrees (regular transmission direction). When measuring the intensity, the brightness of the light source is constant. When measuring the intensity (luminous intensity), the aperture angle of the light receiver detected by the diaphragm of the light receiver is set to 1 degree. For this reason, for example, a range of ± 0.5 degrees is measured for measurement of 0 degree (regular transmission direction), a range of 0.5 to 1.5 degrees is measured for measurement of 1 degree, and a measurement of -1 degree is performed. Then, the range of -0.5 to -1.5 degrees is measured. There is no restriction | limiting in particular about the apparatus which measures intensity | strength, A general purpose goniophotometer (goniophotometer) can be used. In the present invention, a trade name GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. (light beam diameter: about 3 mm, tilt angle within the light beam: within 0.8 degrees, receiver opening angle: 1 degree) is used as the goniophotometer. did.
3-9 is a figure which shows intensity distribution of the transmitted light of the optical sheet of Examples 1-3 and Comparative Examples 1-4.

As described above, after measuring the intensity every degree within a certain range, as shown in FIG. 3, a straight line connecting the intensity at +2 degrees and the intensity at +1 degree with respect to the normal transmission direction is normal transmission. The intensity extrapolated to the angle and the intensity extrapolated to the normal transmission angle from the straight line connecting the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction, and calculated two intensities Is the “virtual intensity in the normal transmission direction”. Based on the “virtual intensity in the normal transmission direction” calculated in this way and the intensity in the normal transmission direction (original intensity in the normal transmission direction), the ratio (intensity ratio in the normal transmission direction / virtual intensity in the normal transmission direction) (intensity ratio) ) Can be calculated.
The intensity distribution diagrams of FIGS. 3 to 9 are approximate curves obtained by linear interpolation of the intensity values for each degree. However, the extrapolation of the straight line to the normal transmission angle when calculating the intensity ratio is an actually measured value. Based on.

Next, what the intensity ratio means will be described.
The optical sheet has a part having a diffusing element (a part having an uneven surface and a part having a diffusing particle inside) and a part having no diffusing element (a part having a substantially smooth surface and no diffusing particle inside). And exist. For this reason, the diffusely transmitted light is a combination of light that does not collide with the diffusing element and “impacts” and light that collides with the diffusing element. In other words, the intensity distribution measured as described above is a combination of “light” light and light impinging on the diffusing element. Therefore, the original intensity in the normal transmission direction shown in FIGS. 3 to 9 is also a combined intensity of the light that passes through and the light that collides with the diffusing element.
On the other hand, glare is thought to be caused by distortion in the transmitted light due to the surface diffusing element of the diffusing elements, so first of all, the diffusion of light that collides with the diffusing element out of the intensity in the normal transmission direction Need to know the characteristics. The virtual intensity in the normal transmission direction can be approximated to the normal transmission of light colliding with the diffusing element.
Therefore, the ratio of [intensity in the normal transmission direction / virtual intensity in the normal transmission direction] is approximated to the ratio of light impinging on the diffusing element. That is, if the intensity ratio is close to 1, it can be said that the ratio of light that passes through the optical sheet collides with the diffusing element is high, and the ratio that the light that transmits through the optical sheet collides with the diffusing element as the intensity ratio becomes larger than 1. It can be said that there is little (in other words, “the ratio of light that can be passed through is large”).
And as above-mentioned, while specifying intensity | strength ratio and defining a surface haze, the grade (surface diffusion element) of an unevenness | corrugation can be represented more concretely.
In addition, since the intensity | strength of a transmission and the intensity | strength of reflection show the substantially same behavior, it can be said that the ratio with which the light which permeate | transmits an optical sheet collides with a diffusion element is high has the high ratio with which external light collides with a diffusion element. . That is, the evaluation of the intensity ratio described above also leads to the evaluation of anti-glare properties.

(Α, β and γ)
α, β and γ are all parameters based on the “virtual intensity” in the normal transmission direction. That is, α, β, and γ are parameters indicating the magnitude of diffusion only in the diffusing element existing portion (the original intensity in the normal transmission direction includes light transmitted through a substantially smooth portion). α is a diffusion angle indicating 1/2 of the virtual intensity in the normal transmission direction, β is a diffusion angle indicating 1/3 of the virtual intensity in the normal transmission direction, and γ is a diffusion angle indicating 1/10 of the virtual intensity in the normal transmission direction. It is. α, β, and γ can be calculated based on an intensity distribution diagram created by an approximate curve by linear interpolation of intensity values for each degree and the virtual intensity in the normal transmission direction calculated as described above.

α means an angle at which a difference from the virtual intensity in the normal transmission direction is not recognized when the display device is visually evaluated. In addition, diffusion elements (internal diffusion elements and surface diffusion elements) that can determine α have a low degree of diffusion. Therefore, when α is large, it means that there are many diffusion elements having a low degree of diffusion, and in the surface diffusion element, there are many irregularities having a small inclination angle.
The optical sheet used for the touch panel of the present invention preferably has an absolute value of α of 1.4 to 3.0 degrees, more preferably 1.5 to 3.0 degrees, and 1.7 to 2. More preferably, it is 5 degrees. By setting the absolute value of α in the above range, unevenness with a small inclination angle exists in a well-balanced manner, and various inclination angles exist within the unevenness, and glare can be more easily prevented. In addition, by setting the absolute value of α in the above range, it is possible to impart antiglare properties and to easily prevent a decrease in resolution due to excessive diffusion. Note that the absolute value of α, the absolute value of β and the absolute value of γ, which will be described later, are average values in the plus direction and the minus direction.

β means a diffusion angle in a range in which a difference from the virtual intensity in the normal transmission direction can be recognized when the display device is visually evaluated. In addition, diffusion elements (internal diffusion elements and surface diffusion elements) that can determine β have a moderate degree of diffusion. Therefore, a large β means that there are many diffusion elements with a medium degree of diffusion, and that there are many irregularities with a medium inclination angle in the surface diffusion elements.
The optical sheet used for the touch panel of the present invention preferably has an absolute value of β of 1.9 to 5.0 degrees, more preferably 2.0 to 4.5 degrees, and 2.3 to 4. More preferably, it is 0 degrees. By setting the absolute value of β in the above range, unevenness with a medium inclination angle exists in a well-balanced manner, and various inclination angles exist within the unevenness, so that glare can be more easily prevented. In addition, by setting the absolute value of β in the above range, it is possible to impart antiglare properties and to easily prevent a decrease in resolution due to excessive diffusion.

γ is an index indicating the bottom of diffusion, that is, how much strong diffusion exists among the diffusion elements. Therefore, a large γ means that there are many diffusing elements having a large degree of diffusion. γ is greatly influenced by the internal diffusion element, but the surface diffusion element means that there are many irregularities with a large inclination angle.
In the optical sheet used in the touch panel of the present invention, the absolute value of γ is preferably 3.5 to 8.0 degrees, more preferably 4.0 to 7.5 degrees, and 4.5 to 6. More preferably, it is 5 degrees. By setting the absolute value of γ to 3.5 degrees or more, various inclination angles are present in the unevenness due to the presence of the unevenness having a large inclination angle, and glare can be more easily prevented. Further, by setting the absolute value of γ to 8.0 degrees or less, it is possible to prevent the optical sheet from being whitened due to excessive unevenness having a large inclination angle, and the optical sheet is used as an antiglare sheet. When used, it is possible to prevent a decrease in contrast.

Further, from the viewpoint of making it easier to obtain the above-described effects of α, β and γ, it is preferable that the absolute values of α, β and γ satisfy one or more of the conditions of the following formulas (II) to (IV), It is more preferable to satisfy two or more of the above, and it is more preferable to satisfy all of the conditions.
2.0 degrees ≦ | γ | − | α | ≦ 5.0 degrees (II)
1.5 degrees ≦ | γ | − | β | ≦ 4.0 degrees (III)
0.5 degrees ≦ | β | − | α | ≦ 2.0 degrees (IV)
| Γ | − | α | is more preferably 2.5 degrees or more and 4.0 degrees or less. Further, | γ | − | β | is more preferably 2.0 degrees or more and 3.5 degrees or less. Furthermore, | β | − | α | is more preferably not less than 0.6 degrees and not more than 1.5 degrees.

The optical sheet preferably has a total light transmittance (JIS K7361-1: 1997) of 80% or more, more preferably 85% or more, and further preferably 90% or more.
The optical sheet preferably has a haze (JIS K7136: 2000) of 25 to 60%, more preferably 30 to 60%, and still more preferably 30 to 50%. By setting the haze to 25% or more, it is possible to impart antiglare properties and make it difficult to see the shape and scratches of the electrode. Further, by setting the haze to 60% or less, it is possible to prevent a decrease in resolution of an ultra-high-definition display element and to easily prevent a decrease in contrast.
Further, the internal haze is preferably 5 to 30%, more preferably 5 to 25%, and further preferably 10 to 18%. By setting the internal haze to 5% or more, glare can be easily prevented by a synergistic effect with the surface irregularities, and by setting the internal haze to 30% or less, it is possible to prevent the resolution of the ultra-high-definition display element from being lowered.
Further, the ratio (Hs / Hi) of the surface haze (Hs) to the internal haze (Hi) is 1.0 to 5.0 from the viewpoint of the balance between the above-described surface haze and the internal haze effect. Is more preferable, 2.0 to 5.0 is more preferable, and 2.5 to 4.5 is still more preferable.

  The optical sheet has a width of 2 mm, 1 mm, 0.5 mm, and 0.125 mm using an image sharpness measuring device defined in JIS K7105: 1981 from the viewpoint of resolution and making it difficult to see the shape and scratches of the electrodes. The sum of the four types of transmitted image clarity through the optical comb is preferably 100% or less, more preferably more than 20% and 80% or less.

  The arithmetic average roughness Ra of the uneven shape of the optical sheet is preferably 0.20 to 0.70 μm, and more preferably 0.25 to 0.50 μm. When Ra is 0.20 μm or more, glare can be easily prevented, antiglare property, adhesion prevention property and interference fringe prevention property can be easily improved, and the shape and scratches of the electrode can be made difficult to see. . In addition, when Ra is set to 0.70 μm or less, it is possible to easily prevent a decrease in resolution and contrast. Ra and Rz and Smp described later are values with a cutoff value of 0.8 mm.

In the present invention, Ra is a two-dimensional roughness parameter Ra described in JIS B0601: 1994, and is expanded three-dimensionally. Orthogonal coordinate axes X and Y axes are placed on a reference plane, and a roughness curved surface is obtained. When Z (x, y) and the size of the reference plane are Lx and Ly, the following formula (1) is used.
A = Lx × Ly
Further, when the above-mentioned Z _{i, j} is used, it is calculated by the following formula (2).
N: All points

The ten-point average roughness Rz of the irregular shape of the optical sheet is preferably 1.00 to 3.50 μm, and more preferably 1.20 to 3.00 μm. By making Rz 1.00 μm or more, it is possible to easily prevent glare, to easily improve antiglare property, adhesion prevention property and interference fringe prevention property, and to make it difficult to see the shape and scratches of the electrode. . Further, by setting Rz to 3.50 μm or less, there is no convex portion having an extremely high altitude, so that it is possible to easily prevent a decrease in resolution and contrast.
Moreover, from the viewpoint of making it easier to obtain the above-described effects of Ra and Rz, the ratio [Rz / Ra] of Rz and Ra is preferably 6.0 or less, and preferably 4.0 to 6.0. Is more preferable, and it is further more preferable that it is 4.5-5.7.

  In the present invention, Rz is obtained by extending Rz, which is a two-dimensional roughness parameter described in JIS B0601: 1994, to three dimensions. A large number of straight lines that pass through the center of the reference surface are placed on the reference surface in a 360-degree radial pattern so as to cover the entire area, and a cross-sectional curve that is cut based on each straight line is obtained from a three-dimensional roughness surface. The point average roughness (the sum of the average of the mountain heights up to the fifth highest from the highest peak and the average of the valley depths up to the fifth deepest from the deepest valley bottom) is obtained. It is calculated by averaging the top 50% of the large number of ten-point average roughness thus obtained.

  The average interval Smp between the concave and convex portions of the optical sheet is preferably 25 to 100 μm, more preferably 30 to 80 μm, and further preferably 30 to 70 μm. By making Smp within the above range, it is possible to make the uneven shape not too loose and not too steep, making it easy to prevent glare, anti-glare property, adhesion prevention, interference fringe prevention, electrode shape and invisibility of scratches It is possible to easily exhibit various performances such as resolution reduction and whitening prevention.

Smp is obtained as follows. Smp, where Ps is the number of ridges of a three-dimensional roughness curved surface that is higher than the reference plane and surrounded by one area, and A is the area of the entire measurement area (reference plane) Is calculated by the following equation (3).
The Ra, Rz and Smp can be calculated by the measurement / analysis application software “MetroPro” attached to the above-described interference microscope “New View” series.

The uneven three-dimensional average inclination angle (θa _3D ) of the optical sheet is preferably 3.0 to 9.0 degrees, more preferably 4.0 to 8.0 degrees, and 4.5 to More preferably, it is 7.0 degrees. By setting θa _3D to 3.0 degrees or more, it is possible to easily impart various characteristics such as anti-glare properties. Further, by setting θa _3D to 9.0 degrees or less, whitening, a reduction in resolution, and a reduction in contrast can be easily prevented. The three-dimensional average inclination angle (θa _3D ) can be calculated by the method described in the examples.

The above-mentioned optical sheet can be used without any particular limitation as long as it has a concavo-convex shape on one surface and has optical transparency.
In addition, the optical sheet may be a single layer of a concavo-convex layer or a multilayer having a concavo-convex layer on a transparent substrate. From the viewpoint of ease of handling and manufacturing, a configuration having an uneven layer on a transparent substrate is preferable.
The optical sheet may have a functional layer such as an antireflection layer, an antifouling layer, or an antistatic layer on the uneven shape and / or on the surface opposite to the uneven shape. Moreover, in the case of a structure having a concavo-convex layer on a transparent base material, a functional layer may be provided between the transparent base material and the concavo-convex layer in addition to the above location.
It is preferable that the surface of the optical sheet opposite to the side having the concavo-convex shape is substantially smooth. For example, when the optical sheet is a single layer of a concavo-convex layer, the surface opposite to the concavo-convex surface is preferably substantially smooth. In the case where the optical sheet has a concavo-convex layer on the transparent substrate, the surface of the transparent substrate opposite to the surface having the concavo-convex layer is preferably substantially smooth. Moreover, when an optical sheet has a functional layer on the surface on the opposite side to an uneven | corrugated shape, it is preferable that the surface of a functional layer is substantially smooth. Here, “substantially smooth” means that Ra is 0.02 μm or less.
In addition, when Ra of the surface on the opposite side to the side having the concavo-convex shape of the optical sheet exceeds 0.02 μm, the surface on the opposite side is substantially smoothed to measure the strength ratio and the surface haze. In order to smooth the surface on the opposite side, a transparent plastic film having a substantially smooth surface can be bonded to the surface on the opposite side through an adhesive layer tape as in the method for measuring haze in the examples. That's fine.

  In order to reduce the noise on the surface of the optical sheet to 22 to 40%, the surface diffusion element may be adjusted. Specifically, the concavo-convex layer is formed from a binder resin and translucent particles, and the surface is controlled by controlling the shape of the translucent particles, the dispersed state of the particles, the particle diameter, the amount of particles added, the thickness of the concavo-convex layer, and the like. The diffusing element can be adjusted. Furthermore, the surface diffusion element preferably takes into account the inclination angle of the unevenness, and the inclination angle of the unevenness can be adjusted by the method described later.

In order to set the intensity ratio of the optical sheet to 1.0 or more and 4.0 or less, it is preferable to increase the ratio of the diffusing elements of the concavo-convex layer and reduce the ratio of light that passes through. For this purpose, it is preferable that the uneven layer has a substantially smooth portion as much as possible, and the entire uneven layer has a slope.
In addition, in order to make α, β and γ (especially β and γ) of the optical sheet within the above-mentioned range, the uneven surface of the optical sheet is not simply made to have a gentle inclination, but an inclination with a large inclination angle is used. It is preferable to mix various included inclination angles.

  Examples of the method for forming irregularities include 1) a method using an embossing roll, 2) an etching treatment, 3) molding by a mold, 4) formation of a coating film by coating, and the like. Among these methods, the molding by the mold 3) is preferable from the viewpoint of reproducibility of the uneven shape, and the formation of the coating film by the coating of 4) is preferable from the viewpoint of productivity and a variety of products.

  Molding with a mold is performed by producing a mold having a shape complementary to the concave and convex surface, pouring a material constituting the concave and convex layer such as a polymer resin or glass into the mold and curing it, and then removing the mold from the mold. be able to. When a transparent substrate is used, a polymer resin or the like is poured into a mold, and after overlaying the transparent substrate on the mold, the polymer resin or the like is cured, and the entire transparent substrate is taken out from the mold. be able to. In addition, when internal diffusion is imparted by translucent particles, additives, or the like, translucent particles, additives, or the like may be poured when the polymer resin or the like is poured into the mold.

The coating film is formed by coating by applying a coating solution for forming a concavo-convex layer containing a resin component and translucent particles onto a transparent substrate by a known coating method such as gravure coating or bar coating. It can be formed by drying and curing. In order to make the strength ratio easily within the range of the present invention, it is preferable to contain inorganic ultrafine particles in the uneven layer forming coating solution.
FIG. 10 is a scanning-type transmission showing a cross-section of the concavo-convex layer of the optical sheet of Example 1 formed by coating a concavo-convex layer-forming coating liquid containing a binder resin, translucent particles and inorganic ultrafine particles. It is an electron micrograph (STEM).
Usually, the surface of the concavo-convex layer is substantially smooth at the places where the light-transmitting particles are not present, but the concavo-convex layer of FIG. 10 has a gentle slope at the places where the translucent particles are not present. This is presumably because the inorganic ultrafine particles affect the thixotropy of the coating solution and the drying characteristics of the solvent, and normal leveling does not occur. As described above, it is considered that a gentle slope is formed even in a portion where the light-transmitting particles are not present, so that a substantially smooth portion is eliminated as much as possible in the concavo-convex layer and the strength ratio is easily within the range of the present invention.

Further, the uneven layer of FIG. 10 has the surface haze and α, β, and γ described above by reducing the reason for the following (1) to (3) and by reducing the number of substantially smooth portions in the uneven layer as described above. It is thought that it can be easily made within the range.
(1) A slightly steep slope where the translucent particles are present and a gentle slope where the translucent particles are not present are mixed to form an uneven shape with random slopes.
(2) Normally, the shape of the concavo-convex layer of the translucent particle existing near the surface of the concavo-convex layer is a convex shape along the shape of the translucent particle. The shape is not in line with the shape of the light-sensitive particles. As described above, the shape of the translucent particles existing in the vicinity of the surface of the uneven layer is not sufficiently reflected in the surface shape of the uneven layer, so that there are few steep unevenness.
(3) In the concavo-convex layer in FIG. 10, the translucent particles are both dispersed and aggregated. This is probably because the inorganic ultrafine particles have an effect on the thixotropic properties of the coating solution and the affinity between the translucent particles. Thus, the presence of both dispersion and agglomeration results in a random surface shape with many variations in the concavo-convex shape.

As the translucent particles, both translucent organic particles and translucent inorganic particles can be used. The translucent particles include shapes such as a spherical shape, a disc shape, a rugby ball shape, and an indeterminate shape, and also include hollow particles, porous particles, solid particles, and the like having these shapes. Among these, spherical solid particles are preferable from the viewpoint of preventing glare.
As translucent organic particles, polymethyl methacrylate, polyacryl-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone, fluorine resin, polyester resin, etc. The particle | grains which become are mentioned.
Examples of the translucent inorganic particles include particles made of silica, alumina, zirconia, titania and the like.
Among the above-described translucent particles, translucent organic particles are preferable from the viewpoint of ease of dispersion control, and among them, polyacryl-styrene copolymer particles are preferable. Since the polyacryl-styrene copolymer particles can easily control the refractive index and the degree of hydrophilicity / hydrophobicity, they are good in that the internal haze and the aggregation / dispersion can be easily controlled. Further, from the viewpoint of making the inside haze the scope of the present invention, the difference in refractive index between the translucent particles and the binder resin is preferably 0.01 to 0.10.

The average particle diameter of the translucent particles is preferably 2 to 10 μm, and more preferably 3 to 8 μm, from the viewpoint of easily making the intensity ratio within the range of the present invention. The average particle diameter of the translucent particles can be calculated by the Coulter counter method.
The ratio of the average particle diameter of the translucent particles to the thickness of the concavo-convex layer (the average particle diameter of the translucent particles / the thickness of the concavo-convex layer) is the intensity ratio, surface haze, α, β and γ of the present invention. From the viewpoint of making the range easy, it is preferably 0.5 to 1.0, and more preferably 0.6 to 0.9.

  The content of the translucent particles is 2 to 25% by mass in the total solid content forming the concavo-convex layer from the viewpoint of making the surface haze, the intensity ratio, and α, β and γ easily within the scope of the present invention. Preferably, it is 5-20 mass%.

Examples of the inorganic ultrafine particles include ultrafine particles made of silica, alumina, zirconia, titania and the like. Among these, silica ultrafine particles are preferable from the viewpoint of transparency.
The inorganic ultrafine particles preferably have an average particle diameter of 1 to 25 nm, more preferably 5 to 20 nm, from the viewpoint of easily making the strength ratio, surface haze, and α, β and γ within the scope of the present invention. The average particle size of the inorganic ultrafine particles can be calculated by converting from the specific surface area measured by the BET nitrogen adsorption method (according to JIS Z8830).

The inorganic ultrafine particles are preferably reactive inorganic ultrafine particles into which a reactive group has been introduced by surface treatment. By introducing a reactive group, a large amount of inorganic ultrafine particles can be contained in the concavo-convex layer, and the strength ratio, surface haze, and α, β, and γ can be easily within the scope of the present invention.
As the reactive group, a polymerizable unsaturated group is suitably used, preferably a photocurable unsaturated group, and particularly preferably an ionizing radiation curable unsaturated group. Specific examples thereof include (meth) acryloyl groups, (meth) acryloyloxy groups, ethylenically unsaturated bonds such as vinyl groups and allyl groups, and epoxy groups.
Examples of such reactive inorganic ultrafine particles include inorganic ultrafine particles surface-treated with a silane coupling agent. In order to treat the surface of the inorganic ultrafine particles with a silane coupling agent, the inorganic ultrafine particles are sprayed with a silane coupling agent, or after the inorganic ultrafine particles are dispersed in a solvent, the silane coupling agent is added and reacted. Examples include a wet method.

The content of the inorganic ultrafine particles is preferably 10 to 90% by mass, more preferably 20 to 70% by mass, and more preferably 35 to 50% by mass in the total solid content forming the uneven layer. Further preferred. By setting it as the said range, intensity ratio, surface haze, and (alpha), (beta), and (gamma) can be easily made into the range of this invention by control of leveling property and suppression of the polymerization shrinkage of an uneven | corrugated layer.
In addition, the ratio of the content of translucent particles and inorganic ultrafine particles in the concavo-convex layer (the content of translucent particles / the content of inorganic ultrafine particles) includes the intensity ratio, the surface haze, and α, β and γ. From the viewpoint of facilitating the range of the invention, it is preferably 0.1 to 0.4, and more preferably 0.2 to 0.3.

  The resin component of the uneven layer preferably includes a thermosetting resin composition or an ionizing radiation curable resin composition, and more preferably includes an ionizing radiation curable resin composition from the viewpoint of improving mechanical strength. Of these, it is more preferable to include an electron beam curable resin composition.

The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating.
Examples of the thermosetting resin include acrylic resin, urethane resin, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin. In the thermosetting resin composition, a curing agent is added to these curable resins as necessary.

The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as “ionizing radiation curable compound”). Examples of the ionizing radiation curable functional group include an ethylenically unsaturated bond group such as a (meth) acryloyl group, a vinyl group, and an allyl group, an epoxy group, and an oxetanyl group. As the ionizing radiation curable compound, a compound having an ethylenically unsaturated bond group is preferable, a compound having two or more ethylenic unsaturated bond groups is more preferable, and among them, having two or more ethylenically unsaturated bond groups, Polyfunctional (meth) acrylate compounds are more preferred. As the polyfunctional (meth) acrylate compound, any of a monomer and an oligomer can be used.
The ionizing radiation means an electromagnetic wave or a charged particle beam having an energy quantum capable of polymerizing or cross-linking molecules, and usually ultraviolet (UV) or electron beam (EB) is used. Electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion beams can also be used.

Among the polyfunctional (meth) acrylate compounds, bifunctional (meth) acrylate monomers include ethylene glycol di (meth) acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, 1,6-hexane. Examples thereof include diol diacrylate.
Examples of the tri- or higher functional (meth) acrylate monomer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, di Examples include pentaerythritol tetra (meth) acrylate and isocyanuric acid-modified tri (meth) acrylate.
The (meth) acrylate-based monomer may be modified by partially modifying the molecular skeleton, and is modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, or the like. Can also be used.

Moreover, examples of the polyfunctional (meth) acrylate oligomer include acrylate polymers such as urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and polyether (meth) acrylate.
Urethane (meth) acrylate is obtained by reaction of polyhydric alcohol and organic diisocyanate with hydroxy (meth) acrylate, for example.
A preferable epoxy (meth) acrylate is a (meth) acrylate obtained by reacting (meth) acrylic acid with a tri- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin or the like. (Meth) acrylates obtained by reacting the above aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins and the like with polybasic acids and (meth) acrylic acid, and bifunctional or higher functional aromatic epoxy resins, It is a (meth) acrylate obtained by reacting an alicyclic epoxy resin, an aliphatic epoxy resin or the like with a phenol and (meth) acrylic acid.
The ionizing radiation curable compounds can be used alone or in combination of two or more.

When the ionizing radiation curable compound is an ultraviolet curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator.
Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzylmethyl ketal, benzoylbenzoate, α-acyloxime ester, thioxanthones, and the like.
These photopolymerization initiators preferably have a melting point of 100 ° C. or higher. By setting the melting point of the photopolymerization initiator to 100 ° C. or higher, the photopolymerization initiator remaining during the formation of the transparent conductive film of the touch panel or the heat of the crystallization process is sublimated, and the low resistance of the transparent conductive film is impaired. Can be prevented.
The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing speed. For example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. One or more selected may be mentioned.

  The thickness of the concavo-convex layer is preferably 2 to 10 μm and more preferably 4 to 8 μm from the viewpoint of balance between curling suppression, mechanical strength, hardness and toughness. The thickness of the concavo-convex layer can be calculated from an average value obtained by selecting 10 points in the cross-sectional photograph of the optical sheet using a scanning transmission electron microscope (STEM).

In the concavo-convex layer forming coating solution, a solvent is usually used in order to adjust the viscosity and to dissolve or disperse each component. Depending on the type of solvent, the surface state of the concavo-convex layer after the coating and drying process is different (in other words, the strength ratio, surface haze and α, β and γ values are different), so the saturated vapor pressure of the solvent, the transparent substrate It is preferable to select the solvent in consideration of the permeability of the solvent to the solvent.
Specifically, the solvent is, for example, ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons. (Cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (butanol, cyclohexanol, etc.) ), Cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.), etc., and mixtures thereof may be used.
When the drying of the solvent is too slow or too fast, it becomes difficult to adjust the strength ratio, the surface haze, and the values of α, β, and γ to the above-described ranges due to excessive or insufficient leveling properties of the uneven layer. Therefore, as a solvent, it is preferable to contain 50 mass% or more of the solvent whose relative evaporation rate (relative evaporation rate when the evaporation rate of n-butyl acetate is 100) is 100 to 180% in the total solvent. As the solvent of 50% by mass or more in the total solvent, those having a relative evaporation rate of 100 to 150 are more preferable.
As examples of the relative evaporation rate, toluene is 195, methyl ethyl ketone (MEK) is 465, methyl isobutyl ketone (MIBK) is 118, and propylene glycol monomethyl ether (PGME) is 68.
The type of solvent also affects the dispersibility of inorganic ultrafine particles typified by silica ultrafine particles. For example, MIBK is suitable in that it has excellent dispersibility of inorganic ultrafine particles, and can easily adjust the strength ratio, surface haze, and α, β, and γ within the above-described ranges.

  Further, from the viewpoint of easily making the intensity ratio, surface haze, and α, β, and γ within the above ranges, it is preferable to control the drying conditions when forming the uneven layer. The drying conditions can be controlled by the drying temperature and the wind speed in the dryer. The specific drying temperature is preferably 30 to 120 ° C. and the drying air speed is preferably 0.2 to 50 m / s. In order to control the leveling of the concavo-convex layer according to the drying conditions, it is preferable that the irradiation with ionizing radiation is performed after drying.

  Further, from the viewpoint of making the surface irregularities moderately smooth so that the strength ratio, surface haze, and α, β, and γ are easily in the above ranges, it is preferable that the irregularity layer forming coating solution contains a leveling agent. Examples of the leveling agent include a fluorine-based or silicone-based one, and a silicone-based leveling agent is preferable. The amount of the leveling agent added is preferably 0.01 to 0.5% by weight, more preferably 0.05 to 0.2% by weight, based on the total solid content of the uneven layer forming coating solution.

The transparent base material of the optical sheet is preferably provided with light transmittance, smoothness, heat resistance and excellent mechanical strength. Such transparent substrates include polyester, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal. , Polyether ketone, polymethyl methacrylate, polycarbonate, polyurethane, and amorphous olefin (Cyclo-Olefin-Polymer: COP). The transparent substrate may be a laminate of two or more plastic films.
Among the above, from the viewpoint of mechanical strength and dimensional stability, polyester (polyethylene terephthalate, polyethylene naphthalate) that has been stretched, particularly biaxially stretched, is preferable. Further, TAC and acrylic are suitable from the viewpoint of light transmitting optical isotropy. Moreover, COP and polyester are suitable in that they are excellent in weather resistance. In addition, a plastic film having a retardation value of 3000 to 30000 nm or a plastic film having a quarter wavelength retardation can prevent unevenness of different colors from being observed on the display screen when an image on a liquid crystal display is observed through polarized sunglasses. This is preferable in terms of points.

The thickness of the transparent substrate is preferably 5 to 300 μm, and more preferably 30 to 200 μm.
In order to improve adhesion, the surface of the transparent substrate may be preliminarily coated with a coating called an anchor agent or a primer in addition to physical treatment such as corona discharge treatment and oxidation treatment.

  The optical sheet may have a functional layer such as an antireflection layer, an antifouling layer, or an antistatic layer on the uneven shape and / or on the surface opposite to the uneven shape. Moreover, in the case of a structure having a concavo-convex layer on a transparent base material, a functional layer may be provided between the transparent base material and the concavo-convex layer in addition to the above location.

[Display device]
The display device of the present invention is a display device having an optical sheet on the front surface of a display element having a pixel density of 300 ppi or more, and the optical sheet has a concavo-convex shape on one surface, and has a surface haze. Is a surface side having a concavo-convex shape with respect to transmitted light that is irradiated with visible light perpendicularly to the optical sheet from a surface direction opposite to the surface having the concavo-convex shape of the optical sheet. The intensity in a certain angle range is measured, and the intensity obtained by extrapolating the straight line connecting the intensity at +2 degrees and the intensity at +1 degree with respect to the normal transmission direction to the normal transmission angle, and -2 with respect to the normal transmission direction. When the average value of the intensity obtained by extrapolating the straight line connecting the intensity at degrees and the intensity at −1 degree to the normal transmission angle is defined as “virtual intensity in the normal transmission direction”, the relationship of the following formula (I) is obtained: To meet.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)

An ultra-high-definition display element having a pixel density of 300 ppi or more is likely to cause glare as described above, but in the present invention, various characteristics such as anti-glare properties can be obtained by using a specific optical sheet as the optical sheet having an uneven shape. In addition, it is possible to prevent glare of image light and a decrease in resolution of an ultra-high-definition display element.
As the optical sheet used for the display device of the present invention, the same optical sheet as used for the touch panel of the present invention described above can be used.

Examples of the display element include a liquid crystal display element, an in-cell touch panel liquid crystal display element, an EL display element, and a plasma display element.
The in-cell touch panel liquid crystal element is a liquid crystal element in which a liquid crystal is sandwiched between two glass substrates, and a touch panel function such as a resistive film type, a capacitance type, and an optical type is incorporated therein. Examples of the liquid crystal display method of the in-cell touch panel liquid crystal element include an IPS method, a VA method, a multi-domain method, an OCB method, an STN method, and a TSTN method. In-cell touch panel liquid crystal elements are described in, for example, Japanese Patent Application Laid-Open Nos. 2011-76602 and 2011-222009.

The optical sheet can be installed on the front surface of the display element in the following order, for example.
(1) Display element / surface protective plate / optical sheet (2) display element / optical sheet (3) display element / optical sheet / surface protective plate (4) touch panel having display element / optical sheet as constituent members (1) and In the case of (2), by arranging the uneven surface of the optical sheet to face the surface (so that the uneven surface faces the side opposite to the display element), it is possible to provide high anti-glare properties and prevent glare. Further, it is possible to prevent a decrease in resolution. In this case, it is also possible to make it difficult to see the scratches on the surface and the display element.
In the case of (3), glare can be prevented while providing various properties such as anti-glare properties by disposing the optical sheet as in the embodiment of the touch panel of the present invention described above.
In the case of (2) and (4), if the concave and convex surface of the optical sheet is arranged through the air layer so as to face the display element side, adhesion and interference fringes can be prevented and scratches generated in the display element can be prevented. It can be difficult to see.
The optical sheet used in the display device of the present invention can suppress reflection of external light even in a bright outdoor environment, and can impart high antiglare properties. Since portable information terminals represented by recent smartphones are often used outdoors, the display device of the present invention uses an optical sheet so that the uneven surface faces the viewer side (the side opposite to the display element). It is preferable.

[Optical sheet]
The optical sheet of the present invention is an optical sheet having a concavo-convex shape on one surface, and the optical sheet has a surface haze of 22 to 40% and the surface having the concavo-convex shape of the optical sheet. Irradiate visible light perpendicularly to the optical sheet from the opposite surface direction, and measure the intensity of a certain angle range from the surface side having the concavo-convex shape for the transmitted light, and the intensity at +2 degrees with respect to the normal transmission direction And the straight line connecting the intensity at +1 degree with the normal transmission angle and the straight line connecting the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction outside the normal transmission angle. When the average value of the inserted intensity is “virtual intensity in the normal transmission direction”, it is used on the front surface of a display element having a pixel density of 300 ppi or more that satisfies the relationship of the following formula (I).
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)

Examples of the optical sheet of the present invention include the same optical sheets used for the touch panel of the present invention described above.
The optical sheet of the present invention is used on the front surface of a display element having a pixel density of 300 ppi or more to prevent glare of image light and a decrease in resolution of an ultra-high-definition display element while providing various properties such as anti-glare properties. It is preferable in that it can be performed.
In addition, the optical sheet of the present invention can suppress reflection of external light even in a bright outdoor environment, and can impart high antiglare properties. Since portable information terminals typified by recent smartphones are often used outdoors, the optical sheet of the present invention has an uneven surface on the outermost surface of the touch panel or display device on the viewer side (the side opposite to the display element). It is preferable to use so that it faces.

[Optical sheet sorting method]
The optical sheet sorting method of the present invention is a method for sorting an optical sheet having a concavo-convex shape on one surface, wherein (a) the surface haze of the optical sheet satisfies 22 to 40%, and (b) the above The optical sheet is irradiated with visible light perpendicularly from the surface opposite to the surface having the concavo-convex shape of the optical sheet, and the intensity of a certain angle range is measured for the transmitted light from the surface side having the concavo-convex shape. Intensity obtained by extrapolating a straight line connecting the intensity at +2 degrees and the intensity at +1 degree to the transmission direction to the normal transmission angle, the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction When the average value of the intensity obtained by extrapolating the straight line connecting to the normal transmission angle is “virtual intensity in the normal transmission direction”, a sheet satisfying the following formula (I) is selected as an optical sheet. Of optical sheets used on the front of display elements It is the law.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)

  The optical sheet sorting method of the present invention sorts an optical sheet that can prevent glare and a decrease in resolution when used in an ultra-high-definition display element having a pixel density of 300 ppi or more without incorporating an optical sheet into a display device. Therefore, the quality control of the optical sheet can be performed efficiently.

The determination conditions for selecting the optical sheet are (a) that the surface haze of the optical sheet satisfies 22 to 40% and (b) that the following formula (I) is satisfied.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)
In the determination condition (a), the haze on the surface of the optical sheet is preferably 25 to 40%, more preferably 25 to 35%. Determination condition (b) is preferably 1.0 ≦ strength ratio ≦ 3.5, more preferably 1.0 ≦ strength ratio ≦ 2.0, and 1.0 ≦ strength ratio ≦ 1.5. More preferably.

Furthermore, by setting one or more selected from the following conditions (c) to (e) as determination conditions, it is possible to more accurately select an optical sheet that can prevent glare and a decrease in resolution. The conditions (c) to (e) are preferably two or more, more preferably all three.
(C) The diffusion angle indicating the half of the virtual intensity in the normal transmission direction is “α”, and the absolute value of α is 1.4 to 3.0 degrees.
(D) The diffusion angle indicating the intensity of 1/3 of the virtual intensity in the normal transmission direction is “β”, and the absolute value of β is 1.9 to 5.0 degrees. (E) 1 / of the virtual intensity in the normal transmission direction. The diffusion angle indicating the intensity of 10 is “γ”, and the absolute value of γ is 3.5 to 8.0 degrees. In the condition (c), the absolute value of α is more preferably 1.5 to 3.0 degrees. Preferably, it is 1.7 to 2.5 degrees.
In the condition (d), the absolute value of β is more preferably 2.0 to 4.5 degrees, and further preferably 2.3 to 4.0 degrees.
In the condition (e), the absolute value of γ is more preferably 4.0 to 7.5 degrees, and further preferably 4.5 to 6.5 degrees.

Furthermore, by using one or more conditions selected from the following conditions (f) to (h) as determination conditions, it is possible to more accurately select an optical sheet that can prevent glare and a decrease in resolution. The conditions (f) to (h) are preferably two or more, and more preferably all three are the determination conditions.
(F) 2.0 degrees ≦ | γ | − | α | ≦ 5.0 degrees (II)
(G) 1.5 degrees ≦ | γ | − | β | ≦ 4.0 degrees (III)
(H) 0.5 degrees ≦ | β | − | α | ≦ 2.0 degrees (IV)
In the condition (f), | γ | − | α | is more preferably 2.5 degrees or more and 4.0 degrees or less. In the condition (g), | γ | − | β | is more preferably 2.0 degrees or more and 3.5 degrees or less. Furthermore, in the condition (h), | β | − | α | is more preferably not less than 0.6 degrees and not more than 1.5 degrees.

[Optical sheet manufacturing method]
The method for producing an optical sheet of the present invention is a method for producing an optical sheet having a concavo-convex shape on one surface, wherein (a) the surface haze of the optical sheet satisfies 22 to 40%, and (b) the above The optical sheet is irradiated with visible light perpendicularly from the surface opposite to the surface having the concavo-convex shape of the optical sheet, and the intensity of a certain angle range is measured for the transmitted light from the surface side having the concavo-convex shape. Intensity obtained by extrapolating a straight line connecting the intensity at +2 degrees and the intensity at +1 degree with respect to the transmission direction to the normal transmission angle, and the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction A display with a pixel density of 300 ppi or more manufactured so as to satisfy the following formula (I) when the average value of the intensity obtained by extrapolating the straight line connecting to the regular transmission angle is “virtual intensity in the provisional regular transmission direction” It is a manufacturing method of the optical sheet used for the front surface of an element.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)

The manufacturing method of the optical sheet of this invention makes it essential to control manufacturing conditions so that the conditions of (a) and (b) may be satisfied. The suitable range of conditions (a) and (b) is the same as that of the selection method of the optical sheet mentioned above. In the optical sheet manufacturing method of the present invention, it is preferable to control the manufacturing conditions so as to satisfy the conditions (c) to (h) of the optical sheet selection method described above as additional conditions.
In the method for producing an optical sheet of the present invention, an optical sheet capable of imparting various properties such as anti-glare properties and efficiently preventing glare of image light and a decrease in resolution of an ultra-high-definition display element having a pixel density of 300 ppi or more is efficiently obtained. Can be manufactured.

The manufacturing condition (a) can be controlled by adjusting the surface diffusing element as described above. Further, in adjusting the surface diffusing element, it is preferable to mix various inclination angles, and for this purpose, it is preferable to incorporate a control means for manufacturing conditions (b) described later.
The production condition (b) can be controlled by increasing the ratio of the diffusing elements in the uneven layer and decreasing the ratio of light that passes through. For this purpose, it is preferable that the uneven layer has a substantially smooth portion as much as possible, and the entire uneven layer has a slope. As a specific means for controlling the manufacturing condition (b), the shape of the mold may be controlled when the uneven layer is formed by a mold. In addition, as described above, the specific means for controlling the production condition (b) when forming the uneven layer by coating is to use an appropriate amount of inorganic ultrafine particles and a solvent having a relative evaporation rate in a specific range. Adjusting drying conditions such as drying temperature and wind speed, and using an appropriate amount of leveling agent.
The manufacturing conditions (c) to (h) can be controlled by mixing various inclination angles including an inclination with a large inclination angle, instead of simply making the concavo-convex surface of the optical sheet have a gentle inclination. Specific means for controlling the production conditions (c) to (h) include the same means as the means exemplified for the means for controlling the production conditions (b).

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples. “Part” and “%” are based on mass unless otherwise specified.

1. Measurement and Evaluation of Physical Properties of Optical Sheets Physical property measurements and evaluations of optical sheets of Examples and Comparative Examples were performed as follows. The results are shown in Table 1.

[Haze]
First, haze (overall haze) was measured according to JIS K-7136: 2000 using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory). In addition, the concavo-convex shape is crushed and flattened by attaching a TAC film of 80 μm thickness (manufactured by FUJIFILM Corporation, TD80UL) to the surface of the optical sheet via a transparent adhesive, eliminating the influence of haze caused by the surface shape. Then, the haze was measured to determine the internal haze (Hi). Then, the surface haze (Hs) was obtained by subtracting the internal haze value from the overall haze value. The light incident surface was the substrate side.
[Strength ratio]
A sample was affixed to a glass plate through a transparent adhesive on the surface opposite to the surface on which the antiglare layer (uneven layer) of each optical sheet obtained in Examples and Comparative Examples was formed. . By using the goniophotometer (GC-5000L, manufactured by Nippon Denshoku Industries Co., Ltd.) by the method described in the specification text, the light source angle is set to 0 degree and the sensitivity is set to 1000 times in the transmission measurement, and the glass surface is set. Install the sample on the light source side, measure the intensity of the transmitted light of the optical sheet every time, create an intensity distribution map of the transmitted light by linear interpolation, and select [Intensity in the normal transmission direction / Virtual in the normal transmission direction] Intensity] ratio (intensity ratio), α, β and γ were calculated. The intensity was measured in a range of ± 20 degrees in the normal transmission direction. The intensity value is a value when the intensity of specularly transmitted light (light receiving angle 0 degree) when a sample is not set as a reference value is 100,000.

[Three-dimensional average inclination angle of optical sheet]
On the surface opposite to the surface on which the antiglare layer (unevenness layer) of each optical sheet obtained in Examples and Comparative Examples is formed, a sample is attached to a glass plate via a transparent adhesive, Using a white interference microscope (New View 7300, manufactured by Zygo), the surface shape of the optical sheet was measured and analyzed under the following conditions. In addition, Microscope Application 8.3.2 Microscope Application was used as measurement / analysis software.
(Measurement condition)
Objective lens: 50 × Zoom: 1 × Measurement area: 414 μm × 414 μm
Resolution (interval per point): 0.44 μm
(Analysis conditions)
Removed: None
Filter: BandPass
FilterType: GaussSpline
Low wavelength: 800 μm
High wavelength: 3 μm
Remove spikes: on
Spike Height (xRMS): 2.5
Note that Low wavelength corresponds to the cutoff value λc in the roughness parameter.
Next, the above-mentioned analysis software (MetroPro ver. 8.3.2-Microscope Application) displays a Slope Map Map screen, and the histogram is displayed as nBins = 100 in the screen, and the histogram data of the three-dimensional surface inclination angle distribution is displayed. Obtained. The section width of each class angle in the histogram was 0.5 degrees or less.
When _i Representative angle of the i-th class of the histogram data theta, the frequency and f _i, the three-dimensional average inclination angle m is calculated by the following formula (4).
Here, N is the total number of data and is calculated by the following equation (5).

[Ra, Rz, Smp of optical sheet]
“Ra” and “SRz” are displayed on the Surface Map screen using the surface shape data obtained when calculating the above-described surface inclination angle distribution and the same analysis conditions, and the numerical values of the optical sheet Ra, Rz.
Next, a “Save Data” button was displayed in the Surface Map screen, and the analyzed three-dimensional curved surface roughness data was saved. Then, the saved data was read by Advanced Texture Application, and the following analysis conditions were applied.
(Analysis conditions)
・ High FFT Filter: off
・ Low FFT Filter: off
・ Remove: Plane
Next, the Peak / Valleys screen was displayed, and the number of peaks was counted from “Peaks Stats”. However, in order to remove a fine peak, a peak whose area is 1 / 10,000 or more of the total measurement area (414 × 414 μm ² ) and whose height is 1/10 or more of Rtm was counted. Rtm can be read from the “Roughness / Waviness Map” screen, and represents the average of the maximum height for each section when the entire measurement area is divided into 3 × 3. And Smp was computed based on the said Formula (3).

[Glitter]
In each of the optical sheets obtained in Examples and Comparative Examples, the surface of the optical sheet on which the antiglare layer is not formed and the glass surface on which the black matrix (glass thickness 0.7 mm) is not formed are transparently adhered. It stuck together with the agent. For the sample thus obtained, a white surface light source (manufactured by HAKUBA, LIGHTBOX, average luminance of 1000 cd / m ² ) was placed on the black matrix side, thereby generating pseudo glare. This was photographed from the optical sheet side with a CCD camera (KP-M1, C mount adapter, close-up ring; PK-11A Nikon, camera lens; 50 mm, F1.4s NIKOR). The distance between the CCD camera and the optical sheet was 250 mm, and the focus of the CCD camera was adjusted to match the optical sheet. Images taken with a CCD camera were taken into a personal computer and analyzed with image processing software (ImagePro Plus ver. 6.2; manufactured by Media Cybernetics) as follows.
First, an evaluation location of 200 × 160 pixels was selected from the captured image, and converted to a 16-bit gray scale at the evaluation location. Next, the low-pass filter was selected from the enhancement tab of the filter command, and the filter was applied under the conditions of “3 × 3, number of times 3, strength 10”. As a result, components derived from the black matrix pattern were removed. Next, flattening was selected, and shading correction was performed under the condition of “background: dark, object width 10”. Next, contrast enhancement was performed with “contrast: 96, brightness: 48” using a contrast enhancement command. The obtained image was converted to an 8-bit gray scale, and the variation in the value for each pixel was calculated as a standard deviation value for 150 × 110 pixels in the image, thereby glaring was digitized. It can be said that the smaller the numerical value of the glare value, the less the glare. Note that the evaluation was performed with the black matrix having a pixel density of 350 ppi or the pixel density of 200 ppi.

[Anti-glare]
An evaluation sample in which a black acrylic plate is bonded to a substrate side of the obtained optical sheet via a transparent adhesive is placed on a horizontal plane, and a fluorescent lamp is placed 1.5 m above the evaluation sample for evaluation. A visual sensory evaluation was performed from various angles in an environment in which a fluorescent lamp was transferred onto the sample and the illuminance on the sample for evaluation was 800 to 1200 Lx, and evaluation was performed according to the following criteria.
○: An image of a fluorescent lamp cannot be recognized from any angle.
Δ: An image of a fluorescent lamp is reflected, but the outline of the fluorescent lamp is blurred and the boundary portion of the outline cannot be recognized.
X: An image of a fluorescent lamp is reflected like a mirror surface, and the outline (boundary boundary) of the fluorescent lamp can be clearly recognized.
[Contrast (dark room)]
In the measurement of contrast ratio, when using a cold cathode tube light source with a diffusion plate installed as a backlight unit, two polarizing plates (AMN-3244TP manufactured by Samsung) were used, and the polarizing plates were installed in parallel Nicols. By dividing L _max of the luminance of light passing through the light by L _min of the luminance of light passing through when installed in crossed Nicol, the antiglare film (light transmissive substrate + antiglare layer) is made the outermost surface. The contrast (L ₁ ) when placed and the contrast (L ₂ ) when only the light-transmitting substrate is placed on the outermost surface are calculated, and (L ₁ / L ₂ ) × 100 (%) is calculated. Thus, the contrast ratio was calculated.
The luminance was measured using a color luminance meter (BM-5A manufactured by Topcon Corporation) in a dark room environment with an illuminance of 5 Lx or less. The measurement angle of the color luminance meter was set to 1 °, and measurement was performed with a visual field of 5 mm from the vertical direction on the sample. The light quantity of the backlight was set such that the luminance when the two polarizing plates were set in parallel Nicol was 3600 cd / m ² without the sample being set.

[Total light transmittance]
The total light transmittance of the optical sheet was measured according to JIS K7361-1: 1997 using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory). The light incident surface was the substrate side.
[Transparent image clarity]
4 types through optical combs having widths of 2 mm, 1 mm, 0.5 mm and 0.125 mm in accordance with JIS K7105: 1981 using image clarity measuring device (trade name: ICM-1T) manufactured by Suga Test Instruments Co., Ltd. The transmitted image definition was measured and the sum of these was calculated.

[Whitening]
A sample in which the surface of the optical sheet on the transparent substrate side and a black acrylic plate were bonded together via a transparent adhesive was prepared. About the produced sample, the cloudiness feeling was observed on the following references | standards in the dark room under the desk stand which uses a 3 wavelength fluorescent lamp tube as a light source.
A: Whiteness was not observed.
C: Whiteness was observed.
[Visibility of scratches]
The concavo-convex surface of the sample optical sheet prepared by the whitening evaluation was rubbed once with # 0000 steel wool at a load of about 100 g / cm ² , and the scratches on the surface were visually evaluated. As a result, “O” indicates that the scratches are not noticeable, and “X” indicates that the scratches are conspicuous.
[Interference fringes]
The two optical sheets were overlapped so that the uneven surface side of one optical sheet and the transparent substrate side of the other optical sheet face each other. As a result, “O” indicates that no interference fringes occurred, and “X” indicates that interference fringes occurred.

2. Production of optical sheet [Example 1]
On a transparent substrate (80 μm thick triacetylcellulose resin film (TAC), manufactured by Fuji Film, TD80UL), the antiglare layer coating solution 1 having the following formulation was applied and dried at 70 ° C. and a wind speed of 5 m / s for 30 seconds. Then, ultraviolet rays were irradiated under a nitrogen atmosphere (oxygen concentration of 200 ppm or less) so that the integrated light amount was 100 mJ / cm ² to form an antiglare layer (concave / convex layer) to obtain an optical sheet. The film thickness of the antiglare layer was 7.5 μm. In addition, Ra on the opposite side to the uneven | corrugated layer of an optical sheet was 0.02 micrometer.

<Anti-glare coating solution 1>
Pentaerythritol triacrylate 10 parts (Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ 45 parts of urethane acrylate (Nippon Gosei Co., Ltd., UV1700B) ・ 3 parts of photopolymerization initiator (Irgacure 184, manufactured by BASF)
・ 0.2 parts of silicone leveling agent (Momentive Performance Materials, TSF4460)
・ Translucent particles 12 parts (Sekisui Plastics Co., Ltd., spherical polyacryl-styrene copolymer)
(Average particle size 6 μm, refractive index 1.535)
・ Inorganic ultrafine particles 160 parts (manufactured by Nissan Chemical Co., Ltd., silica with reactive functional groups introduced on the surface, solvent MIBK, solid content 30%)
(Average primary particle size 12 nm)
・ Solvent 1 (MIBK) 110 parts

[Example 2]
An optical sheet was obtained in the same manner as in Example 1 except that 10 parts of the translucent particles of Example 1 and 170 parts of the inorganic ultrafine particles were changed.

[Example 3]
An optical sheet was obtained in the same manner as in Example 1 except that the light-transmitting particles in Example 1 were changed to 15 parts and the inorganic ultrafine particles were changed to 150 parts.

[Comparative Example 1]
In the same manner as in Example 1, except that the antiglare layer coating solution 1 of Example 1 was changed to the antiglare layer coating solution 2 of the following formulation and the film thickness of the antiglare layer (uneven layer) was 2 μm. A sheet was obtained.
<Anti-glare coating solution 2>
・ 100 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ 14 parts of inorganic fine particles (manufactured by Fuji Silysia Chemical Ltd., gel method amorphous silica)
(Hydrophobic treatment, average particle size (laser diffraction scattering method) 4.1 μm)
-Photopolymerization initiator 5 parts (BASF, Irgacure 184)
・ 0.2 parts of silicone leveling agent (TSF4460 manufactured by Momentive Performance Materials)
・ Solvent 1 (toluene) 150 parts ・ Solvent 2 (MIBK) 35 parts

[Comparative Example 2]
The antiglare layer coating solution 1 of Example 1 was changed to the antiglare layer coating solution 3 of the following formulation, and the film thickness of the antiglare layer (uneven layer) was 4.5 μm, as in Example 1. An optical sheet was obtained.
<Anti-glare layer coating solution 3>
・ 90 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ Acrylic polymer (Mitsubishi Rayon Co., Ltd., molecular weight 75,000) 10 parts ・ Photopolymerization initiator 3 parts (BASF Co., Ltd., Irgacure 184)
・ Silicon-based leveling agent 0.1 part (TSF4460 manufactured by Momentive Performance Materials)
・ 12 parts of translucent particles (manufactured by Soken Chemical Co., Ltd., spherical polystyrene particles)
(Particle size 3.5μ, refractive index 1.59)
・ Solvent 1 (toluene) 145 parts ・ Solvent 2 (cyclohexanone) 60 parts

[Comparative Example 3]
The antiglare layer coating solution 1 of Example 1 was changed to the antiglare layer coating solution 4 having the following formulation, and the film thickness of the antiglare layer (concave / convex layer) was 7.0 μm. An optical sheet was obtained.
<Anti-glare layer coating solution 4>
・ 38 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
Isocyanuric acid EO-modified triacrylate (manufactured by Toa Gosei Co., Ltd., M-313) 22 parts Photopolymerization initiator 5 parts (manufactured by BASF, Irgacure 184)
・ Silicon-based leveling agent 0.1 part (Momentive Performance Materials, TSF4460)
・ Translucent particles 20 parts (Sekisui Plastics Co., Ltd., spherical polyacryl-styrene copolymer)
(Particle size 5μ, refractive index 1.525)
・ Inorganic ultrafine particles 120 parts (manufactured by Nissan Chemical Industries, silica with reactive functional groups introduced on the surface, solvent MIBK, solid content 30%)
(Average primary particle size 12 nm)
・ Solvent 1 (toluene) 135 parts

[Comparative Example 4]
The antiglare layer coating solution 1 of Example 1 was changed to the antiglare layer coating solution 5 of the following formulation, and the film thickness of the antiglare layer (uneven layer) was 5.0 μm, as in Example 1. An optical sheet was obtained.
<Anti-glare layer coating solution 5>
・ 38 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
Isocyanuric acid EO-modified triacrylate (M-313 manufactured by Toa Gosei Co., Ltd.) 22 parts Photopolymerization initiator 5 parts (BASF, Irgacure 184)
・ Silicon-based leveling agent 0.1 part (TSF4460 manufactured by Momentive Performance Materials)
・ Translucent particles 12 parts (Sekisui Plastics Co., Ltd., spherical polyacryl-styrene copolymer)
(Particle size 3.5μ, refractive index 1.545)
・ Inorganic ultrafine particles 120 parts (manufactured by Nissan Chemical Industries, silica with reactive functional groups introduced on the surface, solvent MIBK, solid content 30%)
(Average primary particle size 12 nm)
・ Solvent 1 (toluene) 135 parts

  As is clear from the results in Table 1, the optical sheets of Examples 1 to 3 can impart various properties such as anti-glare properties, and can prevent glare in ultra-high-definition display elements having a pixel density of 300 ppi or more. It was also excellent in contrast. In addition, the optical sheets of Examples 1 to 3 have a much better effect than the optical sheets of Comparative Examples 1 to 4 in terms of antiglare properties of display elements having a pixel density of 350 ppi, but display with a pixel density of 200 ppi. About the glare prevention performance of an element, the difference of an effect with the optical sheet of Comparative Examples 1-4 is small. From this, it can be seen that the optical sheets of Examples 1 to 3 are extremely useful for an ultra-high-definition display element having a pixel density of 300 ppi or more. In addition, although the above-mentioned evaluation of anti-glare property was performed in an environment with an illuminance of 800 to 1200 Lx, the optical sheets of Examples 1 to 3 have good anti-glare properties even in an outdoor environment with an illuminance of 10,000 Lx or more. there were.

3. Production of Touch Panel On the transparent substrate side of the optical sheets of Examples 1 to 3 and Comparative Examples 1 to 4, an ITO conductive film having a thickness of 20 nm was formed by a sputtering method to obtain an upper electrode plate. Next, an ITO conductive film having a thickness of about 20 nm was formed by sputtering on one surface of a 1 mm thick tempered glass plate to obtain a lower electrode plate. Next, ionizing radiation curable resin (Dot Cure TR5903: Taiyo Ink Co., Ltd.) is printed on the surface of the lower electrode plate having the conductive film as a coating solution for spacers in the form of dots by the screen printing method. Irradiation was performed, and spacers having a diameter of 50 μm and a height of 8 μm were arranged at intervals of 1 mm.
Next, the upper electrode plate and the lower electrode plate are arranged so that the conductive films face each other, and the edges are bonded with a double-sided adhesive tape having a thickness of 30 μm and a width of 3 mm. Examples 1-3 and Comparative Examples 1-4 A resistive film type touch panel was prepared.
When the obtained resistive touch panel was placed on a commercially available ultra-high-definition liquid crystal display device (pixel density 350 ppi) and the presence or absence of glare was visually evaluated, glare was suppressed in the touch panels of Examples 1 to 3. Also, there was little transfer of outside light, and visibility was good. In addition, the touch panels of Examples 1 to 3 did not impair the resolution of ultra-high-definition images and had good contrast in a bright room environment. On the other hand, the touch panels of Comparative Examples 1 to 4 were conspicuous. Moreover, since the touch panel of Comparative Example 2 has a relatively high noise inside the optical sheet, the resolution of the ultra-high definition video is slightly impaired.

4). Production of Display Device The optical sheets of Examples 1 to 3 and Comparative Examples 1 to 4 and a commercially available ultra-high-definition liquid crystal display device (pixel density 350 ppi) are bonded together via a transparent adhesive, and Examples 1 to 3 are bonded. And the display apparatus of Comparative Examples 1-4 was produced. In addition, when bonding, the uneven surface of the optical sheet was made to face the side opposite to the display element.
When the presence or absence of glare of the obtained display device was visually evaluated, the display devices of Examples 1 to 3 were suppressed in glare, had little external light, and had good visibility. In addition, the display devices of Examples 1 to 3 did not lose the resolution of the ultra-high-definition video and had good contrast in the bright room environment. On the other hand, the display devices of Comparative Examples 1 to 4 were conspicuous. Further, the display device of Comparative Example 2 has a relatively high noise inside the optical sheet, so that the resolution of the ultra-high definition image is slightly impaired.

1: resistive film type touch panel, 11: transparent substrate, 12: transparent conductive film, 13: spacer 2: capacitive touch panel, 21: transparent substrate, 22: transparent conductive film (X electrode), 23: transparent conductive film ( Y electrode), 24: Adhesive layer

Claims (11)

A touch panel having an optical sheet as a constituent member, the optical sheet having an uneven shape on one surface, having a surface haze of 22 to 40%, and having the uneven shape of the optical sheet. The optical sheet is irradiated with visible light perpendicularly from the surface direction opposite to the surface, and the intensity of a certain angle range is measured from the surface side having the concavo-convex shape with respect to the transmitted light, and +2 degrees with respect to the normal transmission direction The straight line connecting the intensity connecting the intensity at +1 degree and the intensity at +1 degree to the normal transmission angle, and the straight line connecting the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction. When the average value with the intensity extrapolated to the angle is set as the “virtual intensity in the normal transmission direction”, it is used on the front surface of the display element having a pixel density of 300 ppi or more that satisfies the relationship of the following formula (I):
The optical sheet is a single phase of a concavo-convex layer, or a multilayer having a concavo-convex layer on a transparent substrate,
In the uneven layer, containing inorganic ultrafine particles having an average particle diameter of 1 to 25 nm,
The touch panel whose content of the said inorganic ultrafine particle is 35-50 mass% in the total solid which forms the said uneven | corrugated layer.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)   The touch panel according to claim 1, wherein a diffusion angle indicating a luminance of ½ of the virtual intensity in the regular transmission direction is “α”, and an absolute value of α is 1.4 to 3.0 degrees.   The touch panel according to claim 1 or 2, wherein a diffusion angle indicating a luminance of １ ／ of the virtual intensity in the normal transmission direction is “β”, and an absolute value of β is 1.9 to 5.0 degrees.   4. The touch panel according to claim 1, wherein a diffusion angle indicating a luminance of 1/10 of the virtual intensity in the normal transmission direction is “γ”, and an absolute value of γ is 3.5 to 8.0 degrees. . A display device having an optical sheet on the front surface of a display element having a pixel density of 300 ppi or more, wherein the optical sheet has a concavo-convex shape on one surface, and the surface haze is 22 to 40%. In addition, the optical sheet is irradiated with visible light perpendicularly from the surface direction opposite to the surface having the concavo-convex shape of the optical sheet, and the transmitted light has a certain angle range intensity from the surface side having the concavo-convex shape. Measured, the intensity obtained by extrapolating the straight line connecting the intensity at +2 degrees and the intensity at +1 degree with respect to the normal transmission direction to the normal transmission angle, and the intensity at -2 degrees with respect to the normal transmission direction and −1 When the average value of the intensity obtained by extrapolating the straight line connecting the intensity in degrees to the normal transmission angle is “virtual intensity in the normal transmission direction”, the relationship of the following formula (I) is satisfied:
The optical sheet is a single phase of a concavo-convex layer, or a multilayer having a concavo-convex layer on a transparent substrate,
In the uneven layer, containing inorganic ultrafine particles having an average particle diameter of 1 to 25 nm,
The display apparatus whose content of the said inorganic ultrafine particle is 35-50 mass% in the total solid which forms the said uneven | corrugated layer.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I) An optical sheet having a concavo-convex shape on one surface, the optical sheet having a surface haze of 22 to 40%, and the surface direction opposite to the surface having the concavo-convex shape of the optical sheet The optical sheet is irradiated with visible light perpendicularly, and the intensity of the transmitted light is measured within a certain angle range from the surface side having the concavo-convex shape. The intensity at +2 degrees and the intensity at +1 degree with respect to the normal transmission direction The average value of the intensity obtained by extrapolating the straight line connecting the normal transmission angle and the intensity extrapolating the straight line connecting the intensity at -2 degrees and the intensity at -1 degree to the normal transmission angle with respect to the normal transmission angle. Is used for the front surface of a display element having a pixel density of 300 ppi or more, which satisfies the relationship of the following formula (I):
The optical sheet is a single phase of a concavo-convex layer, or a multilayer having a concavo-convex layer on a transparent substrate,
In the uneven layer, containing inorganic ultrafine particles having an average particle diameter of 1 to 25 nm,
The optical sheet whose content of the said inorganic ultrafine particle is 35-50 mass% in the total solid which forms the said uneven | corrugated layer.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)   The optical sheet according to claim 6, wherein a diffusion angle indicating an intensity of ½ of the virtual intensity in the normal transmission direction is “α”, and an absolute value of α is 1.4 to 3.0 degrees.   The optical sheet according to claim 6 or 7, wherein a diffusion angle indicating an intensity of 1/3 of the virtual intensity in the normal transmission direction is "β", and an absolute value of β is 1.9 to 5.0 degrees.   The optical according to any one of claims 6 to 8, wherein a diffusion angle indicating an intensity of 1/10 of the virtual intensity in the normal transmission direction is "γ", and an absolute value of γ is 3.5 to 8.0 degrees. Sheet. A method for selecting an optical sheet having a concavo-convex shape on one surface, wherein (a) the surface haze of the optical sheet satisfies 22 to 40%, and (b) the surface having the concavo-convex shape of the optical sheet. Irradiate visible light perpendicularly to the optical sheet from the opposite surface direction, and measure the intensity of a certain angle range from the surface side having the concavo-convex shape for the transmitted light, and the intensity at +2 degrees with respect to the normal transmission direction And the straight line connecting the intensity at +1 degree with the normal transmission angle and the straight line connecting the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction outside the normal transmission angle. When the average value with the inserted intensity is set as “virtual intensity in the normal transmission direction”, the optical sheet is selected to satisfy the following formula (I), and used for the front surface of the display element having a pixel density of 300 ppi or more.
The optical sheet is a single phase of a concavo-convex layer, or a multilayer having a concavo-convex layer on a transparent substrate,
In the uneven layer, containing inorganic ultrafine particles having an average particle diameter of 1 to 25 nm,
The optical sheet selection method, wherein the content of the inorganic ultrafine particles is 35 to 50 % by mass in the total solid content forming the uneven layer.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I) A method for producing an optical sheet having a concavo-convex shape on one surface, wherein (a) the surface haze of the optical sheet satisfies 22 to 40%, and (b) the surface having the concavo-convex shape of the optical sheet. Irradiate visible light perpendicularly to the optical sheet from the opposite surface direction, and measure the intensity of a certain angle range from the surface side having the concavo-convex shape for the transmitted light, and the intensity at +2 degrees with respect to the normal transmission direction And the straight line connecting the intensity at +1 degree with the normal transmission angle and the straight line connecting the intensity at -2 degrees and the intensity at -1 degree with respect to the normal transmission direction outside the normal transmission angle. When the average value with the inserted intensity is “virtual intensity in the normal transmission direction”, it is used for the front surface of a display element having a pixel density of 300 ppi or more, which is manufactured so as to satisfy the following formula (I):
The optical sheet is a single phase of a concavo-convex layer, or a multilayer having a concavo-convex layer on a transparent substrate,
In the uneven layer, containing inorganic ultrafine particles having an average particle diameter of 1 to 25 nm,
The manufacturing method of the optical sheet whose content of the said inorganic ultrafine particle is 35-50 mass% in the total solid which forms the said uneven | corrugated layer.
1.0 ≦ Intensity in the normal transmission direction / Virtual intensity in the normal transmission direction ≦ 4.0 (I)