JP2018005853A - Writing sheet for touch panel pen, touch panel, display device, and selection method of writing sheet for touch panel pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a writing sheet for a touch panel pen excellent in writing feeling and abrasion resistance.SOLUTION: There is provided a writing sheet for a touch panel, at least one surface of which is a rugged surface satisfying following conditions 1-1 and 1-2. In the condition 1-1, a visible light is radiated to the rugged surface side at an angle of +15 degree from a normal line to measure reflection intensity of reflectance. In measurement of the reflection intensity, a regular reflection direction of the visible light is a reference angle. An angle on a plus direction side from the reference angle which reaches reflection intensity equal to or less than 1/2 of the reflection intensity of the reference angle first is +α, and an angle on a minus direction side from the reference angle which reaches reflection intensity equal to or less than 1/2 of the reflection intensity of the reference angle first is -α. When an average of an absolute value of -αand +αis α, a relation of 4.5 degree≤αis satisfied. In the condition 1-2, a radiation angle of the visible light is changed to an angle of +75 degree from the normal line to measure reflection intensity of the reflectance in a similar manner to the condition 1-1. An angle on a plus direction side from the reference angle which reaches the reflection intensity equal to or less than 1/2 of the reflection intensity of the reference angle first is +α, and an angle on a minus direction side from the reference angle which reaches the reflection intensity equal to or less than the reflection intensity of the reference angle first is -α. When an average of an absolute value of -αand +αis α, αand αsatisfy a relation of α/α≤4.5.SELECTED DRAWING: None

Description

  The present invention relates to a writing sheet for a touch panel pen, a touch panel, a display device, and a method for selecting a writing sheet for a touch panel pen.

  In recent years, touch panels have been installed in many portable information terminals, and the distribution volume has increased. A surface protective sheet may be attached to the surface of the touch panel for various purposes.

Conventionally, the resistance film type touch panel, which has been the mainstream, performs an operation of repeatedly hitting with a finger or a pen, and thus the surface protection sheet is required to have high scratch resistance.
On the other hand, the surface protection sheet of a capacitive touch panel, which is currently the mainstream, is required to have slipperiness when operated with a finger. The conventional resistive film type cannot detect multiple locations at the same time, so it does not move the finger on the screen, but the capacitive touch panel can detect multiple locations simultaneously, and moves the finger on the screen. This is because there are many.
In addition, in common with the resistive film type and the capacitive type, the surface protective sheet for touch panel is required to have the performance of preventing the adhesion of fingerprints when operated with a finger or making the attached fingerprints easy to wipe off. ing.

  For example, Patent Documents 1 and 2 have been proposed as surface protective sheets for touch panels as described above.

JP2015-114939A JP 2014-109712 A JP 2014-097649 A

Since the capacitive touch panel recognizes a touched place by measuring a change in capacitance, the contact object needs to have a certain conductivity. For this reason, at the beginning of the appearance of the capacitive touch panel, only operability with a finger was considered, and writing properties such as drawing characters and pictures with a touch panel pen were not considered. Even in the resistive film type patch panel, the operation when using the touch panel pen is mainly performed by dots, and the writing property when drawing characters and pictures is not considered important.
However, in recent years, touch panel pens that can be input to capacitive touch panels and electromagnetic induction touch panels have begun to be proposed, and the number of applications that support character input and drawing using touch panel pens has increased. The sheet is required to have a good writing feeling with a touch panel pen.
However, as typified by Patent Documents 1 and 2, most of the conventionally proposed surface protective sheets for touch panels have not been examined for writing feeling with a touch panel pen.

On the other hand, Patent Document 3 discloses a surface protective sheet for a touch panel having a surface shape with a rolling circle maximum height waviness of 15 μm or more for the purpose of imparting a writing feeling like a pencil to paper.
As a result of verifying the technique of Patent Document 3 by the present inventors, a predetermined effect was confirmed with respect to writing quality. However, the thing of patent document 3 was a thing with poor abrasion resistance.

  This invention makes it a subject to provide the selection method of the writing sheet for touchscreen pens which was excellent in writing taste and abrasion resistance, a touchscreen, a display apparatus, and the writing sheet for touchscreen pens.

  In order to solve the above-mentioned problems, the present invention provides the following [1] to [4] touch panel pen writing sheet, touch panel, display device, and touch panel pen writing sheet selection method.

[1] A writing sheet for a touch panel, wherein at least one surface is an uneven surface, and the uneven surface satisfies the following conditions 1-1 and 1-2.
<Condition 1-1>
A sample in which a black plate is bonded to the surface of the writing sheet for touch panel opposite to the uneven surface through a transparent adhesive layer is prepared. Visible light is irradiated at an angle of +15 degrees from the normal toward the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the angle of −15 degrees from the normal, which is the normal reflection direction of visible light, is set to a reference angle (0 degree), and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. The angle that is the positive direction side angle from the reference angle and first reaches the reflection intensity that is ½ or less of the reflection intensity of the reference angle is + α ₁₅ , the angle that is the negative direction side from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _15. The absolute value of-.alpha. _15, the average of the + alpha ₁₅ upon the alpha _15, shows the relationship 4.5 ° ≦ alpha _15.
<Condition 1-2>
Visible light is irradiated at an angle of +75 degrees from the normal to the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the angle of −75 degrees from the normal, which is the normal reflection direction of the visible light, is set to a reference angle (0 degree), and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. An angle that is a plus direction side angle from the reference angle and first reaches a reflection intensity that is ½ or less of a reflection intensity of the reference angle is + α ₇₅ , an angle that is a minus direction side angle from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _75. The absolute value of-.alpha. _75, the average of the + alpha ₇₅ upon the alpha _75, and alpha ₇₅ and the alpha ₁₅ indicates the relationship between α ₁₅ / α ₇₅ ≦ 4.5.

[2] A touch panel having a sheet on the surface, wherein the touch panel is configured such that the uneven surface of the writing sheet for a touch panel pen according to [1] faces the surface of the touch panel.
[3] A display device having a touch panel on a display element, wherein the touch panel is the touch panel according to [2].
[4] A method for selecting a writing sheet for a touch panel pen, wherein at least one surface is an uneven surface, and the uneven surface satisfies the above conditions 1-1 and 1-2 as a writing sheet for a touch panel.

  The writing sheet for a touch panel pen, the touch panel, and the display device of the present invention can improve writing quality and wear resistance. Moreover, the method for selecting a writing sheet for a touch panel pen according to the present invention can accurately select a writing sheet for a touch panel pen with good writing taste and wear resistance, and efficiently performs product design and quality control of the writing sheet. can do.

It is sectional drawing which shows one Embodiment of the writing sheet for touchscreen pens of this invention. It is sectional drawing which shows other embodiment of the writing sheet for touchscreen pens of this invention. It is a figure explaining the measuring method of reflection intensity. It is a reflection-intensity distribution figure at the time of irradiating the uneven | corrugated surface of the sample produced from the writing sheet | seat of Example 1 and the comparative example 2 with the visible ray at an angle of +15 degree | times from a normal line. It is a reflection intensity distribution figure at the time of irradiating the concavo-convex surface of the sample produced from the writing sheet of Example 1 with visible light at an angle of +15 degrees from the normal line and an angle of +75 degrees from the normal line. It is a reflection intensity distribution figure at the time of irradiating the uneven | corrugated surface of the sample produced from the writing sheet | seat of the comparative example 3 with the angle of +15 degree | times from a normal line, and the angle | corner of +75 degree | times from a normal line. It is a figure explaining the calculation method of average inclination-angle (theta) a. It is sectional drawing which shows one Embodiment of the touchscreen of this invention. It is sectional drawing which shows other embodiment of the touchscreen of this invention.

  Hereinafter, embodiments of a writing sheet for a touch panel pen, a touch panel, a display device, and a method for selecting a writing sheet for a touch panel pen according to the present invention will be described.

[Writing sheet for touch panel pen]
In the writing sheet for a touch panel pen of the present invention, at least one surface is an uneven surface, and the uneven surface satisfies the following conditions 1-1 and 1-2.
Hereinafter, the writing sheet for a touch panel pen may be referred to as a “writing sheet”.

<Condition 1-1>
A sample in which a black plate is bonded to the surface of the writing sheet for touch panel opposite to the uneven surface through a transparent adhesive layer is prepared. Visible light is irradiated at an angle of +15 degrees from the normal toward the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the direction of −15 degrees from the normal, which is the normal reflection direction of the visible light, is set to the reference angle (0 degree), and the reflection intensity in the direction of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. The angle that is the positive direction side angle from the reference angle and first reaches the reflection intensity that is ½ or less of the reflection intensity of the reference angle is + α ₁₅ , the angle that is the negative direction side from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _15. The absolute value of-.alpha. _15, the average of the + alpha ₁₅ upon the alpha _15, shows the relationship 4.5 ° ≦ alpha _15.

<Condition 1-2>
Visible light is irradiated at an angle of +75 degrees from the normal to the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the angle of −75 degrees from the normal, which is the normal reflection direction of the visible light, is set to a reference angle (0 degree), and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. An angle that is a plus direction side angle from the reference angle and first reaches a reflection intensity that is ½ or less of a reflection intensity of the reference angle is + α ₇₅ , an angle that is a minus direction side angle from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _75. The absolute value of-.alpha. _75, the average of the + alpha ₇₅ upon the alpha _75, and alpha ₇₅ and the alpha ₁₅ indicates the relationship between α ₁₅ / α ₇₅ ≦ 4.5.

<Condition 1-1 and Condition 1-2>
In the writing sheet for a touch panel pen of the present invention, at least one surface is an uneven surface, and the uneven surface satisfies the above conditions 1-1 and 1-2.
First, referring to FIG. 3, a method for measuring the reflection intensity under Condition 1-1 will be described.

First, a sample 100 in which a black plate 30 is bonded to the surface opposite to the uneven surface of the writing sheet for touch panel 10 via the transparent adhesive layer 20 is produced (FIG. 3).
In sample 100, in order to prevent interface reflection, the refractive index difference between the transparent pressure-sensitive adhesive layer 20 and the member (base material, easy-adhesion layer, etc.) in contact with the transparent pressure-sensitive adhesive layer of the writing sheet 10 should be within 0.15. Is preferable, and is preferably within 0.10.
The black plate preferably has a total light transmittance of JIS K7361-1: 1997 of 1% or less, and more preferably 0%.

Next, the visible light is irradiated toward the uneven surface side of the sample 100 at an angle of +15 degrees from the normal direction of the sample, and the reflection intensity of the reflected light is measured. The reference numeral 40 in FIG. 3 corresponds to the normal line of the sample, and the reference numeral 41 corresponds to the visible light irradiated toward the uneven surface side of the sample 100.
In the measurement of the reflection intensity, the angle of −15 degrees from the normal, which is the normal reflection direction of visible light, is set to the reference angle (0 degree), and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is set for each degree. To measure. Reference numeral 42 in FIG. 3 corresponds to the regular reflection direction of visible light (≈reference angle direction), and the range indicated by reference numeral 43 is the measurement range of reflection intensity (≈-12 degrees to +12 degrees including the reference angle). Applicable.

The reflection intensity can be measured, for example, with a goniophotometer. Specifically, the light receiver of the goniophotometer is scanned every 1 degree, and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is measured. When measuring the reflection intensity, the brightness of the light source is constant. Further, when measuring the reflection intensity, the opening angle of the light receiver detected by the stop of the light receiver is set to 1 degree. For this reason, for example, the measurement of the reference angle (0 degree) measures the range of -0.5 degree to +0.5 degree, the measurement of +1 degree measures the range of 0.5 degree to 1.5 degree, In the measurement of -1 degree, the range of -0.5 degree to -1.5 degree is measured.
As a variable angle photometer, for example, trade name GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. (light beam diameter: about 3 mm, light beam tilt angle: within 0.8 degrees, light source: halogen lamp) can be mentioned.
In addition, the reflection intensity of the condition 1-2 is such that the visible light irradiation angle is changed from the normal of the sample to +75 degrees, and the angle of −75 degrees from the normal that is the regular reflection direction of the visible light is changed to the reference angle ( The measurement can be performed in accordance with the above-described method except that it is changed to (0 degree).

Next, the technical significance of Condition 1-1 and Condition 1-2 will be described.
An example of how humans feel good writing is when writing with a pencil on paper. Many fibers are intertwined on the surface of the paper, and when the writing instrument gets over the fibers, moderate friction occurs, and humans feel a pleasant writing taste. For this reason, it is thought that the writing quality of a writing sheet can be made favorable by making the surface shape of a writing sheet moderately uneven | corrugated.
The JIS standard (JIS B0601) concerning the surface shape defines that the surface shape is measured using a contact-type surface shape measuring instrument. However, due to the relationship between the shape of the stylus and the surface shape, the measurement result may not accurately reflect the surface shape. Therefore, the present inventors have found that the surface shape is indirectly represented by the reflection intensity.

Condition 1-1 is a parameter (α ₁₅ ) related to the reflection intensity when the irradiation angle is set to +15 degrees from the normal. When the surface of the writing sheet is substantially smooth, when the sheet is irradiated with visible light at an angle of +15 degrees from the normal, most of the reflected light is directed in the regular reflection direction. On the other hand, when the surface of the writing sheet is an uneven surface, the reflected light is diffused by the inclination of the uneven surface. Moreover, the greater the degree of unevenness, the greater the degree of diffusion.
The solid line in FIG. 4 is a reflection intensity distribution diagram when the concavo-convex surface of the sample produced from the writing sheet of Example 1 is irradiated with visible light at an angle of +15 degrees from the normal, and the broken line in FIG. It is a reflection intensity distribution figure at the time of irradiating the concavo-convex surface of the sample produced from the writing sheet of Example 2 at an angle of +15 degrees from the normal line. In the examples described later, the surface roughness of the writing sheets of Example 1 and Comparative Example 2 is shown. The writing sheet of Example 1 has a higher arithmetic average roughness Ra than the writing sheet of Comparative Example 2. When comparing the solid line in FIG. 4 (Example 1) and the broken line in FIG. 4 (Comparative Example 2), it can be seen that the larger the surface roughness, the larger the ratio of diffusion at a large angle.
Note that the solid line and the broken line in FIG. 4 both standardize the reflection intensity at each angle, with the maximum value of the reflection intensity being 100. In the reflection intensity distribution diagram of FIG. 4, the regular reflection direction of visible light (an angle of −15 degrees from the normal line of the sample) is set as a reference angle (0 degree).

In FIG. 4, the solid line + α ₁₅ is +7.5 degrees, the solid line −α ₁₅ is −8.8 degrees, the broken line + α ₁₅ is +1.7 degrees, and the broken line −α ₁₅ is −2.2 degrees. It can be calculated. Then, “α ₁₅ ”, which is an average value of the absolute value of −α ₁₅ and + α ₁₅ , has a solid line α ₁₅ of 8.2 degrees and a broken line α ₁₅ of 1.9 degrees. That is, when the surface roughness is large reflected light is often the rate of diffusing a large angle, alpha ₁₅ is increased.
+ Α ₁₅ and −α ₁₅ , and + α ₇₅ and −α ₇₅ described later can be read from an intensity distribution diagram created by an approximate curve obtained by linear interpolation of reflection intensity values for each degree.
In the present specification, α ₁₅ and α ₇₅ , S ₁₅ , S ₇₅ and P ₁₂ described later are average values measured ten times.

In condition 1-1 is required to be 4.5 degrees ≦ alpha _15. When α ₁₅ is less than 4.5 degrees, the unevenness is insufficient and the writing quality cannot be improved. If the unevenness is too large, the visibility, wear resistance, and touch of the display element may be reduced, and the touch panel pen may be easily worn. Therefore, α ₁₅ is preferably 4.5 degrees ≦ α ₁₅ ≦ 12.0 degrees, more preferably 6.0 degrees ≦ α ₁₅ ≦ 10.5 degrees, and 7.5 degrees ≦ α. More preferably, ₁₅ ≦ 9.0 degrees.

Condition 1-2 includes a parameter “α ₁₅ ” related to the reflection intensity when the irradiation angle is +15 degrees from the normal line and a parameter “α ₇₅ ” related to the reflection intensity when the irradiation angle is +75 degrees from the normal line. The ratio (α ₁₅ / α ₇₅ ) is a predetermined value.
When the surface of the writing sheet is substantially smooth, the reflection intensity distribution diagram when the writing sheet is irradiated with visible light at an angle of +15 degrees from the normal line, and the writing sheet is irradiated with visible light at an angle of +75 degrees from the normal line. The reflection intensity distribution chart at that time is substantially the same. However, when the surface of the writing sheet is an uneven surface, as the degree of unevenness increases, the reflection intensity distribution diagram of +15 degrees and the reflection intensity distribution chart of +75 degrees are greatly different.

The reason why the shape of the reflection intensity distribution chart of +15 degrees and the reflection intensity distribution chart of +75 degrees is greatly different can be explained as follows.
For example, it is assumed that an appropriate uneven region A exists at an arbitrary position on the uneven surface, and an uneven region B having a steep mountain next to the region A exists. When it is assumed that visible light travels from the region B side, visible light of +15 degrees has a low probability of entering a steep mountain in the region B and a high probability of entering the adjacent region A, The visible light of +75 degrees has a high probability of being incident on a steep mountain in the region B and has a low probability of being incident on the adjacent region A. The visible light incident on the steep mountain is not reflected in the direction of -12 degrees to +12 degrees including the reference angle as a general rule, so that a difference occurs between the reflection intensity distributions.
Therefore, when the shapes of the reflection intensity distribution map of +15 degrees and the reflection intensity distribution chart of +75 degrees are close, it indicates that there are few steep peaks in the unevenness, and the entire structure is gentle unevenness, and conversely +15 When the shape of the reflection intensity distribution chart at a degree and the reflection intensity distribution chart at +75 degrees are greatly different, it indicates that there are many steep peaks in the unevenness.

The solid line in FIG. 5 is a reflection intensity distribution diagram when the concavo-convex surface of the sample prepared from the writing sheet of Example 1 is irradiated with visible light at an angle of +15 degrees from the normal, and the broken line in FIG. It is a reflection intensity distribution figure at the time of irradiating the visible light to the uneven | corrugated surface of the sample produced from the writing sheet | seat of Example 1 at an angle of +75 degree | times from a normal line.
The solid line in FIG. 6 is a reflection intensity distribution diagram when the concavo-convex surface of the sample prepared from the writing sheet of Comparative Example 3 is irradiated with visible light at an angle of +15 degrees from the normal, and the broken line in FIG. It is a reflection intensity distribution figure at the time of irradiating the uneven | corrugated surface of the sample produced from the writing sheet | seat of Example 3 with the visible ray at an angle of +75 degree | times from a normal line.
Note that the solid line and the broken line in FIGS. 5 and 6 both standardize the reflection intensity at each angle, with the maximum value of the reflection intensity being 100. In the reflection intensity distribution diagrams of FIGS. 5 and 6, the regular reflection direction of visible light (an angle of −15 degrees or −75 degrees from the normal line of the sample) is set as a reference angle (0 degree).

  While the arithmetic average roughness Ra of the writing sheet of Example 1 is 0.61 μm, the arithmetic average roughness Ra of the writing sheet of Comparative Example 3 is 0.55 μm, and the degree of roughness of both is similar. is there. However, as shown in the Examples described later, the writing sheet of Comparative Example 3 has a smaller average unevenness interval Sm and local peak average interval S than the writing sheet of Example 1. That is, since the uneven shape of the writing sheet of Comparative Example 3 is given the same height in a shorter cycle than the uneven shape of the writing sheet of Example 1, there are many steep unevenness. For this reason, as shown in FIG. 5, the reflection intensity distribution diagram of Example 1 shows no significant difference in the shape between +15 degree irradiation and +75 degree irradiation, while the reflection intensity distribution diagram of the writing sheet of Comparative Example 3 Therefore, a large difference is confirmed in the shapes of +15 degree irradiation and +75 degree irradiation.

Condition 1-2 requires that α ₁₅ / α ₇₅ is 4.5 or less. When α ₁₅ / α ₇₅ exceeds 4.5, it means that there are many steep peaks in the unevenness. And if there are many steep peaks in the irregularities, when wiping off dust, fingerprints, etc. on the surface of the writing sheet with a cloth, etc. Peeling easily occurs, whitening occurs, and wear resistance cannot be improved. In addition, when there are many steep peaks in the unevenness, the touch panel pen tends to wear out.
α ₁₅ / α ₇₅ is preferably 3.0 or less, more preferably 2.0 or less, further preferably 1.5 or less, and even more preferably 1.3 or less. . Α ₁₅ / α ₇₅ is preferably more than 1.0.

Moreover, it is preferable that the writing sheet of this invention satisfy | fills the following conditions 1-3 further.
<Condition 1-3>
The maximum value of “the reflection intensity of visible light irradiated at an angle of +15 degrees from the normal line of the sample” measured in the condition 1-1 is defined as 100, and the reflection intensity at each angle is normalized. The sum of the reflection intensity of each angle normalized to S _15.
The maximum value of the “reflection intensity of visible light irradiated at an angle of +75 degrees from the normal line of the sample” measured in the condition 1-2 is defined as 100, and the reflection intensity at each angle is normalized. The sum of the reflection intensity of each angle normalized to S _75.
And S ₁₅ and _{S 75 indicates} the relationship between the _S 15 _/ S ₇₅ ≦ 2.0.

By satisfying Condition 1-3, it is possible to improve the wear resistance of the writing sheet and to easily suppress the wear of the touch panel pen.
S ₁₅ / S ₇₅ is more preferably 1.8 or less, further preferably 1.6 or less, and still more preferably 1.4 or less.

The writing sheet of the present invention preferably further satisfies the following conditions 1-4.
<Condition 1-4>
The maximum value of “the reflection intensity of visible light irradiated at an angle of +15 degrees from the normal line of the sample” measured in the condition 1-1 is defined as 100, and the reflection intensity at each angle is normalized. With respect to the reference angle (0 degrees) which is set at the conditions 1-1, the normalized reflection intensity of -12 degrees, +12 degrees average of the normalized reflection intensity to P _12.
P ₁₂ is shows the relationship 10.0 ≦ _{P 12.}

With the P ₁₂ 10.0 or more, unevenness becomes large, it is possible to better the writing feeling. If the unevenness is too large, the visibility, wear resistance, and touch of the display element may be reduced, and the touch panel pen may be easily worn. Therefore, P ₁₂ is more preferably 20.0 ≦ P ₁₂ ≦ 45.0, and further preferably 25.0 ≦ P ₁₂ ≦ 35.0.

Moreover, it is preferable that the writing sheet of this invention satisfy | fills the following conditions 2-1.
<Condition 2-1>
JIS K7136: 2000 haze is 25.0% or more

By setting the haze to 25.0% or more, it is possible to easily suppress glare (a phenomenon in which minute variations in luminance are seen in video light).
From the viewpoint of suppressing glare, the haze is more preferably 35.0% or more, and further preferably 45.0% or more. Further, from the viewpoint of suppressing a decrease in resolution of the display element, the haze is preferably 90.0% or less, more preferably 70.0% or less, and 65.0% or less. More preferably, it is still more preferably 63.0% or less.
When measuring haze and the total light transmittance described later, light is incident from the surface opposite to the concavo-convex surface satisfying the conditions 1-1 and 1-2. When both surfaces of the writing sheet satisfy the conditions 1-1 and 1-2, the light incident surface may be either surface. In addition, let haze and a total light transmittance be the average value at the time of measuring 10 times.

Moreover, it is preferable that the writing sheet of this invention satisfy | fills the following conditions 2-2.
<Condition 2-2>
JIS K7361-1: 1997 has a total light transmittance of 87.0% or more

By setting the total light transmittance to 87.0% or more, a decrease in luminance of the display element can be suppressed.
The total light transmittance is more preferably 88.0% or more, and further preferably 89.0% or more.

Moreover, it is preferable that the writing sheet of this invention satisfy | fills the following conditions 3-1.
<Condition 3-1>
The contact angle of pure water on the uneven surface is 94 degrees or more.

By making the contact angle of pure water on the uneven surface to be 94 degrees or more, it is possible to easily suppress the adhesion of dirt, to improve the wiping property of dust, dust, etc. adhering to the surface, and to touch with a finger. It is possible to easily improve the touch feeling (sliding condition of fingers). In addition, by setting the contact angle of pure water on the uneven surface to 94 degrees or more, it is possible to easily improve wear resistance and to suppress wear of the touch panel pen.
The contact angle of pure water on the uneven surface is more preferably 100 ° or more, and further preferably 105 ° or more.

  The contact angle of pure water and the contact angle of hexadecane, which will be described later, are determined by dropping 1.5 μL of a sample (pure water or hexadecane) on the concavo-convex surface. It can be calculated from the angle of the straight line connecting the end point and the vertex with respect to the uneven surface. The contact angle is an average value measured five times. Moreover, the room temperature at the time of measuring a contact angle shall be 20 degreeC. In calculating the contact angle, both ends of the uneven surface with which the sample is in contact are regarded as straight lines.

Moreover, it is preferable that the writing sheet of this invention satisfy | fills the following conditions 3-2.
<Condition 3-2>
The contact angle of hexadecane on the uneven surface is 40 degrees or more.

By setting the contact angle of hexadecane on the uneven surface to 40 degrees or more, it is possible to easily suppress the adhesion of fingerprints, to improve the wiping property of fingerprints adhering to the surface, and when touching with a finger. Tactile feel can be improved. Moreover, by setting the contact angle of hexadecane on the concavo-convex surface to 40 degrees or more, it is possible to easily improve wear resistance and to suppress wear of the touch panel pen.
The contact angle of hexadecane on the uneven surface is more preferably 50 degrees or more, and further preferably 60 degrees or more.

  In the writing sheet of the present invention, from the viewpoint of improving the scratch resistance of the concavo-convex surface, the pencil hardness of JIS K5600-5-4: 1999 is preferably 2H or higher, and preferably 3H or higher. More preferably, it is more preferably 5H or more.

<Configuration of the entire writing sheet>
The structure of the writing sheet for a touch panel pen of the present invention is not particularly limited as long as at least one surface is an uneven surface and the uneven surface satisfies the conditions 1-1 and 1-2.
FIG.1 and FIG.2 is sectional drawing which shows one Embodiment of the writing sheet 10 for touchscreen pens of this invention. The writing sheet 10 for a touch panel pen in FIG. 1 has a concavo-convex layer 2 on one surface of a substrate 1, and the surface of the concavo-convex layer 2 is an uneven surface. The writing sheet 10 for a touch panel pen in FIG. 2 has a concavo-convex layer 2 and an overcoat layer 3 on one surface of a substrate 1, and the surface of the overcoat layer 3 is a concavo-convex surface.
The writing sheet may have an uneven surface satisfying the conditions 1-1 and 1-2 on both sides of the writing sheet. However, from the viewpoint of handleability and display element visibility, the conditions 1-1 and 1 It is preferable that an uneven surface satisfying −2 is provided on one side, and the other surface is substantially smooth (Ra 0.02 μm or less).
In addition, although not shown in figure, the structure which does not have a base material may be sufficient as the structure of the writing sheet 10 for touchscreen pens of this invention.

  The uneven surface can be formed by “physical or chemical treatment such as embossing, sandblasting, etching”, “molding with a mold”, “coating” or the like. Among these methods, “molding with a mold” is preferable from the viewpoint of reproducibility of the surface shape, and “coating” is preferable from the viewpoint of productivity and compatibility with various products.

In order for the writing sheet to satisfy Condition 1-1, Condition 1-2, and the like, it is preferable that the uneven surface of the writing sheet satisfies the following physical properties (a) to (f). The following physical properties (a) to (f) are average values of 10 measurements.
Note that the cut-off values for calculating Ra, Rz, θa, λa, etc., which will be described later, are all 0.8 mm. The reason for setting the cut-off value to 0.8 mm is that a value close to the diameter (around 1.0 mm) of the pen tip of the touch panel pen is selected from the cut-off specified in JIS B0633.

(A) Arithmetic mean roughness Ra of JIS B0601: 1994 of the uneven surface is 0.25 μm or more and 1.00 μm or less.
(B) The ten-point average roughness Rz of JIS B0601: 1994 of the irregular surface is 2.0 μm or more and 4.0 μm or less.
(C) The average inclination angle θa of the uneven surface is 3.0 degrees or more and 9.5 degrees or less.
(D) The average wavelength λa calculated from the θa and the Ra based on the equation [λa = 2π × (Ra / tan (θa))] is 40 μm or more and 150 μm or less.
(E) Convex / concave surface JIS B0601: 1994 average concavity and convexity interval Sm is 48 μm or more and 150 μm or less.
(F) JIS B0601: 1994 local peak sum average interval S of the uneven surface is 20 μm or more and 80 μm or less.

Of the above physical properties (a) to (f), (a) to (c) represent the degree of unevenness, and (d) to (f) represent the period of unevenness. Therefore, by satisfying the physical properties (a) to (f), it is possible to reduce the ratio of steep peaks in the unevenness while having unevenness of a predetermined size. 2 can be satisfied easily. For this reason, satisfying the physical properties (a) to (f) also leads to good writing quality and wear resistance.
In addition, by satisfying the above physical properties (a) to (f), it is possible to easily improve the anti-fingerprint adhesion to the uneven surface and the touch feeling when touched with a finger, and to reduce glare and wear of the pen tip of the touch panel pen. Can be easily suppressed. For example, if the unevenness is large and the unevenness period is in an appropriate range, the contact area between the finger and the uneven surface is reduced, and the adhesion of fingerprints to the uneven surface and the touch feeling when touching with the finger are good. It is easy to do. However, even if the unevenness is large and the unevenness period is in an appropriate range, if the unevenness is too large, the touch becomes poor. Also, if the size of the unevenness and the period of the unevenness are in an appropriate range, the touch panel pen's nib moves as if sliding on the tip of the convex part, and the wear of the touch panel pen is suppressed while having an appropriate writing quality. can do.

Ra in the above (a) is more preferably 0.40 μm or more and 0.75 μm or less, and further preferably 0.50 μm or more and 0.70 μm or less.
Rz in the above (b) is more preferably 2.5 μm or more and 3.8 μm or less, and further preferably 3.0 μm or more and 3.6 μm or less.
Θa in the above (c) is more preferably 4.5 degrees or more and 9.0 degrees or less, and more preferably 8.5 degrees or more and 7.5 degrees or less.
Λa in the above (d) is more preferably 45 μm or more and 100 μm or less, and further preferably 50 μm or more and 70 μm or less.
The Sm in the above (e) is more preferably 50 μm or more and 100 μm or less, and further preferably 50 μm or more and 70 μm or less.
S in the above (f) is more preferably 22 μm or more and 50 μm or less, and further preferably 24 μm or more and 30 μm or less.

The “average inclination angle θa”, which is the basis for calculating λa in (d) above, is the instruction manual (revised 1995.07.20) of the surface roughness measuring instrument (trade name: SE-3400) manufactured by Kosaka Laboratory. ), And as shown in FIG. 7, the arc tangent θa = tan of the sum of the heights of the convex portions existing in the reference length L (h ₁ + h ₂ + h ₃ +... + H _n ) ⁻¹ {(h ₁ + h ₂ + h ₃ +... + H _n ) / L}.

Formation of the concavo-convex surface by coating is performed by applying a concavo-convex layer forming coating solution containing a resin component, particles and a solvent onto a substrate by a known application method such as gravure coating or bar coating, drying and curing. Can be formed.
In order for the uneven surface formed by coating to easily satisfy the conditions 1-1, 1-2, etc., the average particle diameter of the particles, the content of the particles, the thickness of the uneven layer, and the like may be within the ranges described below. preferable.
Moreover, it is preferable to have an overcoat layer on an uneven | corrugated layer from a viewpoint of making it easy to satisfy | fill conditions 1-2 by reducing the ratio of the steep peak in an unevenness | corrugation. By forming the overcoat layer on the concavo-convex layer, the groove of the concavo-convex layer is partially filled, and the condition 1-2 can be easily satisfied.

Either organic particles or inorganic particles can be used as the particles of the uneven layer.
Examples of the organic particles include particles made of polymethyl methacrylate, polyacryl-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone, fluorine resin, and polyester resin. Can be mentioned.
Examples of the inorganic particles include particles made of silica, alumina, antimony, zirconia, titania and the like. Among inorganic particles, silica having excellent transparency is preferable. The inorganic particles are preferably those whose surfaces have been subjected to a hydrophobic treatment. Hydrophobic treated inorganic particles have good dispersibility in the concavo-convex layer-forming coating solution, are suppressed from agglomeration, and can easily satisfy the conditions 1-1 and 1-2. Moreover, since the hydrophobic treated inorganic particles have good affinity with the resin component, it is possible to easily prevent the particles from falling off the coating film.
The shape of the particles may be either spherical or irregular. Spherical particles are suitable for forming smooth irregularities, and irregular particles are excellent in suppressing glare.
These particles may be used alone or in combination of two or more.

It is preferable that the particles of the concavo-convex layer use organic particles and inorganic particles in combination, and that the average particle size of the organic particles is larger than the average particle size of the inorganic particles. With such a configuration, smooth irregularities can be formed with organic particles having a large particle diameter, while fine irregularities can be formed with inorganic particles to improve the writing quality. In addition, since the inorganic particles are small, it is possible to impart hardness to the coating film with the inorganic particles, while it is possible to suppress wear of the touch panel pen caused by a large number of hard inorganic particles protruding from the coating film.
When organic particles and inorganic particles are used in combination, the shape of the organic particles is preferably spherical from the viewpoint of forming smooth unevenness. When organic particles and inorganic particles are used in combination, the shape of the inorganic particles is not particularly limited, but is preferably indefinite from the viewpoint of suppressing glare.

Although the average particle diameter of the particles in the concavo-convex layer varies depending on the thickness of the concavo-convex layer, it cannot be said unconditionally. However, from the viewpoint of easily satisfying the conditions 1-1 and 1-2, From the viewpoint of suppressing wear of the touch panel pen, 1.0 to 10.0 μm is preferable, 2.0 to 8.0 μm is more preferable, and 3.0 to 6.0 μm is even more preferable. When the particles are aggregated, the average particle diameter of the aggregated particles preferably satisfies the above range.
When organic particles and inorganic particles are used in combination, the average particle size of the organic particles and the average particle size of the inorganic particles are 1.0 <[average particle size of organic particles / average particle size of inorganic particles] ≦ 1. And preferably 1.1 ≦ [average particle diameter of organic particles / average particle diameter of inorganic particles] ≦ 1.4.
The average particle diameter of the particles can be calculated by the following operations (y1) to (y3).
(Y1) A transmission observation image of the writing sheet of the present invention is taken with an optical microscope. The magnification is preferably 500 to 2000 times.
(Y2) Arbitrary 10 particles are extracted from the observation image, and the particle diameter of each particle is calculated. The particle diameter is measured as a distance between straight lines in a combination of two straight lines that maximizes the distance between the two straight lines when the cross section of the particle is sandwiched between two parallel straight lines.
(Y3) The same operation is performed five times on the observation image of another screen of the same sample, and the value obtained from the number average of the particle diameters for a total of 50 particles is taken as the average particle diameter of the particles in the uneven layer.

  Even if the particles have a wide particle size distribution (single particles with a wide particle size distribution, or mixed particles obtained by mixing two or more types of particles having different particle size distributions). However, it is preferable that the particle size distribution is narrow from the viewpoint of suppressing the glare, the viewpoint of suppressing the dropping of the particles, and the viewpoint of suppressing the wear of the touch panel pen. Specifically, the variation coefficient of the particle size distribution of the particles is preferably 25% or less, more preferably 20% or less, and further preferably 15% or less.

The content of the particles in the concavo-convex layer is preferably 10 to 25 parts by mass with respect to 100 parts by mass of the resin component from the viewpoint of easily satisfying the conditions 1-1 and 1-2. More preferably, it is a mass part, and it is still more preferable that it is 15-20 mass part.
When organic particles and inorganic particles are used in combination, the mass ratio of organic particles: inorganic particles is preferably 1: 1 to 1:20, more preferably 1: 3 to 1:15, More preferably, it is 1: 5 to 1:10.

The preferable range of the thickness of the uneven layer is slightly different depending on the embodiment of the uneven layer. For example, the thickness of the concavo-convex layer including particles is 2.0 to 8.8 from the viewpoint of easily satisfying the conditions 1-1 and 1-2, the viewpoint of improving the pencil hardness of the concavo-convex surface, and the suppression of curling. 0 μm is preferable, 2.5 to 6.0 μm is more preferable, and 3.0 to 4.5 μm is more preferable.
Moreover, from the viewpoint of easily satisfying the conditions 1-1 and 1-2, the viewpoint of suppressing the dropout of the particles, and the viewpoint of suppressing the wear of the touch panel pen, the [average particle diameter of particles] / [the uneven layer including particles] The ratio of the film thickness] is preferably 0.7 to 1.8, more preferably 0.8 to 1.7, and still more preferably 0.9 to 1.5.
The film thickness of the concavo-convex layer can be calculated, for example, by measuring the thickness of 20 locations from a cross-sectional image taken using a scanning transmission electron microscope (STEM) and calculating the average value of 20 locations. The STEM acceleration voltage is preferably 10 kv to 30 kV, and the STEM magnification is preferably 1000 to 7000 times.

  The resin component of the concavo-convex layer preferably contains a cured product of a thermosetting resin composition or an ionizing radiation curable resin composition. From the viewpoint of improving the pencil hardness of the concavo-convex surface, the ionizing radiation curable resin composition is cured. It is more preferable that the product contains an ultraviolet 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 remaining photopolymerization initiator sublimates in the manufacturing process of the writing sheet and the transparent conductive film of the touch panel, and the manufacturing apparatus and the transparent conductive film Contamination 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.

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. Since the surface state of the concavo-convex layer after the coating and drying process varies depending on the type of solvent, it is preferable to select the solvent in consideration of the saturated vapor pressure of the solvent, the permeability of the solvent into the transparent substrate, and the like. 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, it becomes difficult to form a surface shape that easily satisfies the conditions 1-1, 1-2, etc., due to excessive leveling of the uneven layer and / or agglomeration of particles. Become. Therefore, the solvent preferably contains 50% by mass or more of a solvent having an evaporation rate (relative evaporation rate when the evaporation rate of n-butyl acetate is 100) of 180 or more, and 60% by mass. More preferably included. An example of the solvent having a relative evaporation rate of 180 or more includes toluene. The relative evaporation rate of toluene is 195.

  Further, from the viewpoint of making the surface shape moderately smooth and making the surface shape of the writing sheet easy to be in the above-described range, it is preferable that the uneven layer forming coating solution contains a leveling agent. Examples of the leveling agent include a fluorine-based leveling agent, a silicone-based leveling agent, and a fluorosilicone copolymer-based leveling agent. The addition amount of the leveling agent is preferably 0.01 to 0.30 mass%, more preferably 0.02 to 0.10 mass%, based on the total solid content of the uneven layer forming coating solution. In addition, the leveling agent leads to good tactile sensation.

<Overcoat layer>
It is preferable that an overcoat layer is provided on the uneven layer, and the surface of the overcoat layer is the uneven surface. By forming the overcoat layer on the concavo-convex layer, the groove of the concavo-convex layer is partially filled, and the condition 1-2 can be easily satisfied.
From the above viewpoint, it is preferable that the overcoat layer does not substantially contain particles having an average particle diameter of 200 nm or more. Specifically, particles having an average particle diameter of 200 nm or more in the total solid content of the overcoat layer are preferably 1.0% by mass or less, more preferably 0.1% by mass or less, and 0% by mass. More preferably.
From the above viewpoint, the thickness of the overcoat layer is preferably 30 to 350 nm, more preferably 130 to 300 nm, and further preferably 150 to 250 nm.
The film thickness of the overcoat layer can be calculated, for example, by measuring the thickness at 20 locations from a cross-sectional image taken using a scanning transmission electron microscope (STEM) and calculating the average value of the 20 locations. The STEM acceleration voltage is preferably 10 kv to 30 kV, and the STEM magnification is preferably 50,000 to 300,000 times.

The overcoat layer is a coating solution for forming an overcoat layer containing a resin component, a solvent, and a functional material to be added as necessary. The overcoat layer is applied onto a substrate by a known application method such as gravure coating or bar coating. It can be formed by drying and curing. Examples of the functional material added as necessary include a low refractive index agent, an antifouling agent, and an antistatic agent.
In the step of forming the overcoat layer, it is preferable that the thermosetting resin composition or ionizing radiation curable resin composition of the concavo-convex layer be in a semi-cured state. By forming the overcoat layer in such a step, the adhesion between the uneven layer and the overcoat layer can be improved.

Here, from the viewpoint of easily satisfying the conditions 1-1 and 1-2, the solid content of the overcoat layer forming coating solution is preferably 1.5 to 5.0% by mass, and 2.0 to 3 It is more preferable to set it as 0.0 mass%, and it is still more preferable to set it as 2.2-2.7 mass%. By setting the solid content of the overcoat layer forming coating solution in the above-described range, the amount of solid content of the overcoat layer on the convex portion of the concave / convex layer is small, while the groove portion of the concave / convex layer (especially a sharp mountain) The amount of solid content of the overcoat layer on the peripheral groove portion) is increased, and the conditions 1-1 and 1-2 can be easily satisfied. Moreover, wear of the touch panel pen can be suppressed by increasing the amount of solid content of the overcoat layer to the groove portion of the uneven layer (particularly, the groove portion around the steep mountain).
When the solid content of the overcoat layer adheres evenly to the surface of the concavo-convex layer, the concavo-convex layer becomes smooth as a whole and the writing quality tends to deteriorate. That is, it is preferable that the solid content of the overcoat layer-forming coating solution is in the above-mentioned range because it leads to suppression of deterioration in writing quality.

  As the resin component of the overcoat layer, the same resin component as that of the uneven layer described above can be used.

As the solvent for the overcoat layer forming coating solution, the same solvents as those exemplified for the uneven layer forming coating solution can be used.
When the drying of the solvent of the overcoat layer forming coating solution is too slow, the overcoat layer forming coating solution excessively flows into the groove portion of the concavo-convex layer to form a surface shape that easily satisfies the conditions 1-1 and 1-2. It becomes difficult. Accordingly, the solvent preferably contains 50% by mass or more of a solvent having an evaporation rate (relative evaporation rate when the evaporation rate of n-butyl acetate is 100) of 150 or more, and 60% by mass. More preferably, it is more preferably 80% by mass or more. Examples of the solvent having a relative evaporation rate of 150 or more include methyl isobutyl ketone. The relative evaporation rate of methyl isobutyl ketone is 160.

The overcoat layer preferably has a refractive index of 1.45 or less, more preferably 1.26 to 1.40, and even more preferably 1.28 to 1.38. By setting the refractive index of the overcoat layer in the above-described range and making the surface of the overcoat layer the uneven surface, reflection on the surface of the writing sheet can be suppressed. When the surface of the writing sheet satisfies the condition 1-1, the whiteness of the writing sheet tends to increase due to the diffusion of reflected light, but the writing quality is improved by forming an overcoat layer having a refractive index of 1.45 or less. While being good, the whiteness of the writing sheet can be suppressed.
In order to make the refractive index of the overcoat layer 1.45 or less, it is preferable to contain a low refractive index agent in the overcoat layer.
The refractive index of the overcoat layer can be calculated, for example, by fitting the reflection spectrum measured with a reflection photometer and the reflection spectrum calculated from the multilayer thin film optical model using the Fresnel coefficient. In the present specification, the refractive index means a refractive index at a wavelength of 550 nm.

Examples of the low refractive index agent include silica and magnesium fluoride. From the viewpoint of reducing the refractive index, a porous low refractive index agent and a hollow low refractive index agent are preferable. As the low refractive index agent, porous silica and hollow silica are suitable, and in order to improve dispersibility in the overcoat layer forming coating solution, hydrophobic treated porous silica and hollow silica are more suitable. .
The content of the low refractive index agent is preferably 20 to 70% by mass and more preferably 30 to 60% by mass in the total solid sentence of the overcoat layer from the viewpoint of the balance between the refractive index and the coating film strength. Preferably, it is more preferable that it is 40-50 mass%.
When the low refractive index agent has a particle shape, the average primary particle size is preferably less than 200 nm, more preferably 10 to 100 nm, and further preferably 20 to 80 nm.

The average primary particle diameter of the particulate low refractive index agent can be calculated by the following operations (z1) to (z3).
(Z1) The cross section of a writing sheet is imaged with TEM or STEM. The acceleration voltage of TEM or STEM is preferably 10 kv to 30 kV, and the magnification is preferably 50,000 to 300,000 times.
(Z2) Arbitrary 10 particles are extracted from the observation image, and the particle diameter of each particle is calculated. The particle diameter is measured as a distance between straight lines in a combination of two straight lines that maximizes the distance between the two straight lines when the cross section of the particle is sandwiched between two parallel straight lines.
(Z3) The same operation is performed five times on the observation image of another screen of the same sample, and the value obtained from the number average of the particle diameters for a total of 50 particles is taken as the average primary particle diameter of the particulate low refractive index agent. .

  The overcoat layer preferably contains an antifouling agent. By including an antifouling agent in the overcoat layer, it is possible to easily suppress the adhesion of dirt, to facilitate the wiping of dirt adhering to the surface, and to feel the touch when touched with a finger. Can be easily improved. In addition, by including an antifouling agent in the overcoat layer, it is possible to easily improve the wear resistance and to easily suppress wear of the touch panel pen.

Examples of the antifouling agent include fluorine-containing compounds, polyorganosiloxane, and polyorganosiloxane containing fluorine in the molecule. Fluorine-containing compounds are preferable from the viewpoint of suppressing the adhesion of dirt and wiping properties of dirt, and polyorganosiloxane is preferable from the viewpoint of tactile sensation (slipperiness) and suppression of wear of the touch panel pen. In addition, polyorganosiloxane containing fluorine in the molecule is preferable in that it is excellent in suppressing adhesion of dirt, wiping of dirt, tactile sensation, and wear control of touch panel pens.
The polyorganosiloxane containing fluorine in the molecule preferably has a structure having a structure having a siloxane bond as a basic skeleton and an organic group containing fluorine in the side chain of the siloxane bond. Moreover, it is preferable that the fluorine is contained in the organic group as a perfluoropolyether group from the viewpoint of suppressing the adhesion of dirt and the wiping property of dirt.
The antifouling agent preferably has an ionizing radiation curable functional group in the molecule in order to maintain the antifouling agent characteristics for a long period of time.

  The most preferred antifouling agent is a polyorganosiloxane containing fluorine and ionizing radiation curable functional groups in the molecule. The structure of the antifouling agent has a structure having a siloxane bond as a basic skeleton, has two or more organic groups in the side chain of the siloxane bond, and has a perfluoropolyether group in at least one organic group. And, it is preferable that the structure has an ionizing radiation-curable functional group in at least one organic group. The organic group containing a perfluoropolyether group and the organic group having an ionizing radiation curable functional group are preferably different organic groups.

  The content of the antifouling agent is preferably 0.25 to 15% by mass in the total solid sentence of the overcoat layer from the viewpoint of imparting characteristics by the antifouling agent and the balance of the coating film strength, and is preferably 1 to 10% by mass. % Is more preferable, and 2.5 to 7% by mass is even more preferable.

<Base material>
As the substrate, a light-transmitting plastic film is suitable.
Light-transmitting plastic films are 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).
Among these plastic films, from the viewpoint of easily satisfying the mechanical strength, dimensional stability, and the above physical property (f), a stretched polyester film, particularly a biaxially stretched polyester film is preferable. Among the polyester films, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferable.
The thickness of the base material is preferably 5 to 200 μm, and more preferably 10 to 150 μm.
An easy-adhesion layer may be formed on the base material in order to improve adhesion such as an uneven layer. In addition, in order to suppress interface reflection, the refractive index difference between the base material and the easy-adhesion layer is preferably within 0.15, and more preferably within 0.10.

[Touch panel]
The touch panel of this invention is a touch panel which has a sheet | seat on the surface, Comprising: As the said sheet | seat, the said uneven surface (uneven surface satisfying the conditions 1-1 and 1-2) of the writing sheet for touch panel pens of this invention is a touch panel. It is arranged so as to face the surface.

  Examples of the touch panel include a resistive touch panel, a capacitive touch panel, an in-cell touch panel, an optical touch panel, an ultrasonic touch panel, and an electromagnetic induction touch panel.

  As shown in FIG. 8, the resistive touch panel 100 is not illustrated in a basic configuration in which a conductive film 300 of a pair of upper and lower transparent substrates 200 having a conductive film 300 is disposed via a spacer 400 so as to face each other. A circuit is connected. In the case of a resistive touch panel, the writing sheet 10 of the present invention is used as the upper transparent substrate 200, and the writing sheet 10 is used so that the uneven surface faces the surface of the touch panel 1000. The upper transparent substrate 200 may have a configuration in which another base material is bonded to a writing sheet.

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 configured by connecting a circuit to a basic configuration in which an X-axis electrode and a Y-axis electrode orthogonal to the X-axis electrode are arranged via an insulator. The basic configuration will be described more specifically. A mode in which X-axis electrodes and Y-axis electrodes are formed on separate surfaces on a single transparent substrate, and an X-axis electrode, an insulator layer, and a Y-axis electrode are formed on the transparent substrate. In this embodiment, as shown in FIG. 9, an X-axis electrode 500 is formed on a transparent substrate 200, a Y-axis electrode 600 is formed on another transparent substrate 200, and an insulating layer such as an adhesive layer The aspect which laminates | stacks through 700, etc. are mentioned. Moreover, the aspect which laminate | stacks another transparent substrate in these basic aspects is mentioned.
In the case of a capacitive touch panel, the writing sheet 10 of the present invention is used as the transparent substrate 200 on the front side, and the uneven surface of the writing sheet 10 faces the surface of the touch panel 1000. The transparent substrate 200 on the front side may have a configuration in which another base material is bonded to a writing sheet.

  An electromagnetic induction touch panel is a touch panel that uses a dedicated pen that generates a magnetic field. The electromagnetic induction touch panel has at least a sensor unit that detects electromagnetic energy generated from the pen, and further includes a transparent substrate on the sensor unit. The transparent substrate may have a multilayer structure. In the case of an electromagnetic induction type touch panel, among the transparent substrates located on the sensor unit, the writing sheet of the present invention is used as the outermost transparent substrate, and the uneven surface of the writing sheet is used so as to face the surface of the touch panel. .

The in-cell touch panel incorporates a touch panel function such as a resistance film type, a capacitance type, and an optical type inside a liquid crystal element in which a liquid crystal is sandwiched between two glass substrates.
In the case of an in-cell touch panel, the indented surface of the writing sheet of the present invention is arranged and used on a glass substrate on the front side so as to face the surface of the touch panel. In addition, you may have other layers, such as a polarizing plate, between the glass substrate of the surface side of an in-cell touch panel, and the writing sheet of this invention.

[Display device with touch panel]
The display device with a touch panel of the present invention is a display device having a touch panel on a display element, and the touch panel is the touch panel of the present invention.

  Examples of the display element include a liquid crystal display element, an EL display element, a plasma display element, and an electronic paper element. When the display element is a liquid crystal display element, an EL display element, a plasma display element, or an electronic paper element, the touch panel of the present invention is placed on these display elements.

[Selection method of writing sheet for touch panel pen]
The method for selecting a writing sheet for a touch panel pen according to the present invention is such that at least one surface is an uneven surface, and the uneven surface satisfies the following conditions 1-1 and 1-2 as a touch panel writing sheet. is there.

<Condition 1-1>
A sample in which a black plate is bonded to the surface of the writing sheet for touch panel opposite to the uneven surface through a transparent adhesive layer is prepared. Visible light is irradiated at an angle of +15 degrees from the normal toward the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the direction of −15 degrees from the normal, which is the normal reflection direction of the visible light, is set to the reference angle (0 degree), and the reflection intensity in the direction of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. The angle that is the positive direction side angle from the reference angle and first reaches the reflection intensity that is ½ or less of the reflection intensity of the reference angle is + α ₁₅ , the angle that is the negative direction side from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _15. The absolute value of-.alpha. _15, the average of the + alpha ₁₅ upon the alpha _15, shows the relationship 4.5 ° ≦ alpha _15.

<Condition 1-2>
Visible light is irradiated at an angle of +75 degrees from the normal to the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the angle of −75 degrees from the normal, which is the normal reflection direction of the visible light, is set to a reference angle (0 degree), and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. An angle that is a plus direction side angle from the reference angle and first reaches a reflection intensity that is ½ or less of a reflection intensity of the reference angle is + α ₇₅ , an angle that is a minus direction side angle from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _75. The absolute value of-.alpha. _75, the average of the + alpha ₇₅ upon the alpha _75, and alpha ₇₅ and the alpha ₁₅ indicates the relationship between α ₁₅ / α ₇₅ ≦ 4.5.

  According to the method for selecting a writing sheet for a touch panel pen of the present invention, it is possible to accurately select a writing sheet for a touch panel pen having good writing taste and wear resistance, and efficient product design and quality control of the writing sheet. can do.

The conditions for selecting the writing sheet are (1-1) 4.5 degrees ≦ α ₁₅ and (1-2) α ₁₅ / α ₇₅ ≦ 4.5 as essential conditions.
The preferable range of α ₁₅ of the selection condition (1-1) and α ₁₅ / α ₇₅ of the selection condition (1-2) is the same as the preferable range shown in the writing sheet of the present invention.

  Moreover, the selection method of the writing sheet for touch-panel pens of this invention is mentioned below from a viewpoint etc. which sort more accurately the writing sheet for touch-panel pens with favorable writing taste and abrasion resistance (1-3), ( It is preferable that one or more selected from the group of 1-4), (2-1), (2-2), (3-1) and (3-2) be an additional selection condition. The additional selection conditions are more preferably two or more of the group, more preferably four or more, and even more preferably all.

<Condition 1-3>
The maximum value of “the reflection intensity of visible light irradiated at an angle of +15 degrees from the normal line of the sample” measured in the condition 1-1 is defined as 100, and the reflection intensity at each angle is normalized. The sum of the reflection intensity of each angle normalized to S _15.
The maximum value of the “reflection intensity of visible light irradiated at an angle of +75 degrees from the normal line of the sample” measured in the condition 1-2 is defined as 100, and the reflection intensity at each angle is normalized. The sum of the reflection intensity of each angle normalized to S _75.
And S ₁₅ and _{S 75 indicates} the relationship between the _S 15 _/ S ₇₅ ≦ 4.5.
<Condition 1-4>
The maximum value of “the reflection intensity of visible light irradiated at an angle of +15 degrees from the normal line of the sample” measured in the condition 1-1 is defined as 100, and the reflection intensity at each angle is normalized. With respect to the reference angle (0 degrees) which is set at the conditions 1-1, the normalized reflection intensity of -12 degrees, +12 degrees average of the normalized reflection intensity to P _12.
P ₁₂ is shows the relationship 10.0 ≦ _{P 12.}
<Condition 2-1>
Writing sheet JIS K7136: 2000 haze is 25.0% or more <Condition 2-2>
The total light transmittance of JIS K7361-1: 1997 of the writing sheet is 87.0% or more <Condition 3-1>
The contact angle of pure water on the uneven surface is 94 degrees or more.
<Condition 3-2>
The contact angle of hexadecane on the uneven surface is 40 degrees or more.

  The preferable range of the additional selection conditions is the same as the preferable range shown in the writing sheet of the present invention.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.

1. Measurement and Evaluation The following measurement and evaluation were performed on the writing sheet for touch panel pen prepared or prepared in the experimental example.

1-1. Reflection intensity 10 cm in length by optically transparent adhesive sheet (refractive index: 1.47, thickness 100 μm) manufactured by Toray Industries, Inc. on the surface opposite to the uneven surface of the writing sheet for touch panel (surface on the base material side) A sample in which a black plate having a width of 10 cm (made by Kuraray Co., Ltd., trade name: Comoglass product number: DFA502K, thickness 2.0 mm) was bonded was prepared.
Visible light was irradiated at an angle of +15 degrees from the normal line toward the uneven surface side of the sample, and the reflection intensity of the reflected light was measured. In the measurement of the reflection intensity, the direction of −15 degrees from the normal, which is the normal reflection direction of visible light, is set to the reference angle (0 degree), and the reflection intensity in the direction of −12 degrees to +12 degrees including the reference angle is measured every degree. Measured.
Further, visible light was irradiated at an angle of +75 degrees from the normal toward the uneven surface side of the sample, and the reflection intensity of the reflected light was measured. In the measurement of the reflection intensity, the direction of −75 degrees from the normal, which is the normal reflection direction of visible light, is set to the reference angle (0 degree), and the reflection intensity in the direction of −12 degrees to +12 degrees including the reference angle is measured every degree. Measured.
Based on the above measurement results, the numerical values related to the conditions 1-1 to 1-4 were calculated based on the description in the specification text. The results are shown in Table 1.

1-2. Haze, total light transmittance Using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory), haze (JIS K-7136: 2000) and total light transmittance (JIS K7361-1: 1997) were measured. . The light incident surface was the substrate side. The results are shown in Table 1.

1-3. Contact angle A 1.5 μL sample (pure water or hexadecane) is dropped on the uneven surface, and the angle of the straight line connecting the left and right end points and the apex of the dropped droplet to the uneven surface 1 second after landing, according to the θ / 2 method From this, the contact angle of the sample (pure water or hexadecane) was calculated. The contact angle was an average value measured five times. Moreover, the room temperature at the time of measuring a contact angle was 20 degreeC. The light incident surface was the substrate side. The results are shown in Table 1.

1-4. Surface shape Using a surface roughness measuring instrument (model number: SE-3400 / manufactured by Kosaka Laboratory Co., Ltd.), the surface shape on the uneven layer side of the writing sheet for a touch panel pen is measured under the following measurement conditions. It was measured. The results are shown in Table 1.
<Measurement conditions>
[Surface probe for surface roughness detection]
Product name SE2555N manufactured by Kosaka Laboratory Ltd. (tip radius of curvature: 2 μm, apex angle: 90 degrees, material: diamond)
[Measurement conditions of surface roughness measuring instrument]
・ Feeding speed of stylus: 0.1 mm / s
・ Vertical magnification: 2000 times ・ Horizontal magnification: 10 times ・ Evaluation length: 4 mm
・ Preliminary length: 0.8mm
<Measurement item>
-Arithmetic average roughness Ra of JIS B0601: 1994 with a cut-off value of 0.8 mm
-JIS B0601: 1994 ten-point average roughness Rz with a cut-off value of 0.8 mm
・ Average inclination angle θa with cut-off value 0.8mm
・ Average wavelength λa with cutoff value 0.8mm
-JIS B0601: 1994 average spacing Sm of cut-off value 0.8mm
-JIS B0601: 1994 local summit average interval S with a cut-off value of 0.8 mm

1-5. Writing taste The surface on the opposite side of the surface of the writing sheet for touch panel pens was bonded to a glass plate, and the writing taste was evaluated using a touch panel pen (trade name “BB-2 accessory pen” manufactured by King Jim). .
Twenty people evaluated that the writing quality was 2 points, the normal one was 1 point, and the unsatisfactory was 0 point. The average score of 20 people was “A” when the score was 1.6 or more, “B” when the score was 1.0 or more and less than 1.6, and “C” when the score was less than 1.0. The results are shown in Table 1.

1-6. Abrasion resistance The steel sheet (trade name: Bonster B-204, grade: # 0000) manufactured by Nippon Steel Wool Co., Ltd. was used for the uneven surface of the writing sheet, and two load conditions (300 g / m ² , 400 g / m rubbing test ²⁾ was performed 10 reciprocating times, those that do not occur whether the was visually evaluated. load 400 g / m ^2, even whitening whitening coating due to dropping of the particles has occurred "a", the load Whitening did not occur at 300 g / m ² , but whitening occurred at a load of 400 g / m ² was designated “B”, and whitening occurred at a load of 300 g / m ² was designated as “C.” The results are shown in Table 1. .

1-7. Pen wear As shown in FIG. 10, a touch panel pen (trade name “BB-2 accessory pen” manufactured by King Jim Co., Ltd.) 51 is brought into contact with the surface on the uneven layer side of the writing sheet 10 for a touch panel pen at an angle of 60 degrees. And fixed with a holder 54. A weight 53 of 100 g was placed on the base 55 above the holder so that a vertical load of 100 gf was applied to the touch panel pen 51. While the load was applied, the movable table 52 to which the writing sheet 10 was fixed was reciprocated at a speed of 14 mm / second and the length of 40 mm one way was repeated 50 times, and a maximum of 4 cycles was repeated.
After completion of each cycle, it was confirmed whether or not the wear of the tip of the touch panel pen could be easily confirmed visually. As a result, “A” indicates that wear cannot be confirmed even after completion of 4 cycles, and “B” indicates that wear cannot be confirmed after completion of 3 cycles, but “B” indicates that wear has been confirmed after completion of 4 cycles. The case where wear was confirmed was designated as “C”. The results are shown in Table 1.
The measuring apparatus used was the trade name “HEIDON-14DR” manufactured by Shinto Kagaku Co., Ltd., the mode was “constant load reciprocating friction measurement mode”, and the temperature during evaluation was 23 ° C.

1-8. Tactile (slippery)
The operation of moving the finger pad against the surface on the uneven layer side of the writing sheet for touch panel pen and moving it up, down, left and right was performed.
Twenty people evaluated the tactile sensation (slidability) as 2 points, the normal one as 1 point, and the unsatisfactory as 0 point. The average score of 20 people was “A” when the score was 1.6 or more, “B” when the score was 1.0 or more and less than 1.6, and “C” when the score was less than 1.0. The results are shown in Table 1.

1-9. Fingerprint Adhesion, Fingerprint Wipeability Fingertips were pressed against the surface of the concavo-convex layer side of the touch panel pen writing sheet, and the fingerprint adhesion was visually evaluated. “A” indicates that the fingerprint is difficult to adhere, and “C” indicates that the fingerprint is likely to adhere. The results are shown in Table 1.
Further, using a non-woven fabric (manufactured by Asahi Kasei Co., Ltd., trade name: Ben Cotton), the attached fingerprint was wiped off, and the number of times until the trace of the fingerprint disappeared was evaluated. “A” indicates that the fingerprint is not visible after wiping up to 3 times, “B” indicates that the fingerprint is not visible after wiping 4 to 7 times, and “C” indicates that the fingerprint is visible after 7 times of wiping. did. The results are shown in Table 1.

1-10. Glitter The touch-panel pen writing sheet was placed on a commercially available ultra-high-definition liquid crystal display device (pixel density 350 ppi), and the glare state was visually evaluated. Twenty people evaluated 20 points where glare was in a level that could not be visually recognized, 1 point where glare was slightly observed but 1 point was not noticeable, and 0 point where glare was severely observed. The average score of 20 people was “A” when the score was 1.6 or more, “B” when the score was 1.0 or more and less than 1.6, and “C” when the score was less than 1.0. The results are shown in Table 1.

1-11. Whitening In a bright room environment with an illuminance of 1000 Lx, irradiation with a 30 W three-wavelength fluorescent lamp was performed at an angle of 45 degrees with respect to the uneven surface side of the sample, and the whitening state was visually evaluated. 15 subjects evaluated, "A" if 10 or more responded good (not white), "B" if 5-9 answered good, 4 or less answered good The thing was set to "C". The results are shown in Table 1.

2. Preparation of writing sheet for touch panel pen [Example 1]
As a base material, a PET film having a thickness of 100 μm (a base material in which an easy-adhesion layer having a refractive index of 1.55 is formed on both surfaces of a PET film having a refractive index of 1.65) is used. The formed coating solution 1 was applied, dried, and irradiated with ultraviolet rays so that the thickness after drying was 4 μm to form an uneven layer.
Next, an overcoat layer (refractive index of 1.37) is formed on the concavo-convex layer by applying an overcoat layer-forming coating solution 2 having the following formulation so that the thickness after drying is 200 nm, drying, and ultraviolet irradiation. The touch panel pen writing sheet was obtained. The ionizing radiation curable resin composition of the uneven layer is in a semi-cured state at the stage of forming the uneven layer, and then the ionizing radiation curable resin composition of the uneven layer and the overcoat layer is formed at the stage of forming the overcoat layer. The product was completely cured.

<Uneven layer forming coating solution 1>
・ Pentaerythritol triacrylate 60 parts ・ Dipentaerythritol hexaacrylate 40 parts ・ Organic particles 2 parts (spherical polystyrene particles, average particle size 5.0 μm)
・ 15 parts of inorganic particles (hydrophobized amorphous silica, average particle size of 4.0 μm)
・ 3.5 parts of photopolymerization initiator (BASF, Irgacure 184)
・ Fuso leveling agent 0.1 parts (manufactured by DIC, MegaFac RS-75)
・ Solvent 1 (toluene) 120 parts ・ Solvent 2 (cyclohexanone) 50 parts

<Overcoat layer forming coating solution 2>
・ 100 parts of polyfunctional acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30) 90 parts of hollow silica particles (average primary particle diameter 60 nm)
-Antifouling agent A 5 parts below-Photopolymerization initiator 7 parts (BASF, Irgacure 127)
・ Solvent 1 (methyl isobutyl ketone) 7500 parts ・ Solvent 2 830 parts (propylene glycol monomethyl ether acetate)

<Anti-fouling agent A>
A compound produced according to Example 1 of JP 2010-53114 A (having a structure having a siloxane bond as a basic skeleton and having two or more organic groups in the side chain of the siloxane bond, and at least one organic group A compound having a perfluoropolyether group in it and an ionizing radiation-curable functional group in at least one organic group)

[Example 2]
A writing sheet for a touch panel pen was obtained in the same manner as in Example 1 except that the thickness of the uneven layer was changed to 3 μm and the addition amount of the antifouling agent A in the overcoat layer coating solution was changed to 10 parts.

[Comparative Example 1]
On the same substrate as in Example 1, the uneven layer forming coating solution 3 having the following formulation was applied, dried, and irradiated with ultraviolet rays so that the thickness after drying was 5 μm to form an uneven layer, and writing for a touch panel pen A sheet was obtained.

<Uneven layer forming coating solution 3>
・ 81 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ 13 parts of organic particles (spherical polyacryl-styrene copolymer, average particle size 3.5 μm)
・ 6 parts of fumed silica (average primary particle size 10 nm)
Photopolymerization initiator 3 parts (BASF, Irgacure 184)
・ 0.001 part of silicone leveling agent (Momentive Performance Materials, TSF4460)
・ Solvent 1 (toluene) 180 parts ・ Solvent 2 (anone) 70 parts ・ Solvent 3 (methyl isobutyl ketone) 2 parts ・ Solvent 4 28 parts (propylene glycol monomethyl ether acetate)

[Comparative Example 2]
On the same base material as in Example 1, a concavo-convex layer forming coating solution 4 having the following formulation was applied, dried, and irradiated with ultraviolet rays so that the thickness after drying was 7 μm to form a concavo-convex layer, and writing for a touch panel pen A sheet was obtained.

<Uneven layer forming coating solution 4>
・ 83 parts of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ 11 parts of organic particles (spherical polystyrene, average particle size 3.5 μm)
・ 7 parts of fumed silica (average primary particle size 10 nm)
Photopolymerization initiator 3 parts (BASF, Irgacure 184)
・ Silicon-based leveling agent 0.125 parts (Momentive Performance Materials, TSF4460)
・ Solvent 1 (toluene) 225 parts ・ Solvent 2 (anone) 3 parts ・ Solvent 3 (methyl isobutyl ketone) 50 parts ・ Solvent 4 (isopropyl alcohol) 28 parts

[Comparative Example 3]
On the same substrate as in Example 1, the uneven layer forming coating solution 5 having the following formulation was applied, dried, and irradiated with ultraviolet rays so that the thickness after drying was 3 μm to form an uneven layer, and writing for a touch panel pen A sheet was obtained.

<Uneven layer forming coating solution 5>
・ Pentaerythritol triacrylate 60 parts ・ Dipentaerythritol hexaacrylate 40 parts ・ Organic particles 2 parts (spherical polystyrene particles, average particle size 5.0 μm)
-15 parts of inorganic particles (hydrophobized amorphous silica, average particle size 3.0 μm)
・ 3.5 parts of photopolymerization initiator (BASF, Irgacure 184)
・ Fuso leveling agent 0.1 parts (manufactured by DIC, MegaFac RS-75)
・ Solvent 1 (toluene) 120 parts ・ Solvent 2 (cyclohexanone) 50 parts

As shown in Table 1, the writing sheets of Examples 1 and 2 satisfying Condition 1-1 and Condition 1-2 are compatible with writing performance and wear resistance, and have other performance such as wear suppression of the touch panel pen. Was also excellent. More specifically referring to the wear resistance and wear control of the touch panel pen, the writing sheet of Example 1 is mainly because the condition 1-2 is in the optimum range (α ₁₅ / α ₇₅ is 1.3 or less). Abrasion resistance and wear control of touch panel pen are good. On the other hand, in the writing sheet of Example 2, Condition 1-2 is not the optimum range, but compared with Example 1, the contact angle is large, so that the wear resistance and the wear suppression of the touch panel pen are good. .
On the other hand, the writing sheets of Comparative Examples 1 and 2 that did not satisfy Condition 1-1 were inferior in writing quality. Moreover, although the writing sheet of the comparative example 3 satisfy | filled the conditions 1-1 and was excellent in writing quality, it did not satisfy | fill the conditions 1-2 but was inferior to abrasion resistance. In the writing sheets of Comparative Examples 1 and 2, Condition 1-2 is not in the optimum range (α ₁₅ / α ₇₅ is 1.3 or less), but wear resistance and wear control of the touch panel pen are good. . This is because the writing sheets of Comparative Examples 1 and 2 have a small value of Condition 1-1 and a small degree of unevenness.

  Moreover, from the results of Table 1, it can be confirmed that selecting a writing sheet satisfying the conditions 1-1 and 1-2 leads to efficiently selecting a writing sheet having excellent writing quality and wear resistance.

3. Production of Touch Panel A conductive film of ITO having a thickness of 20 nm is formed on the surface opposite to the uneven surface of the writing sheet for touch panel pens of Examples 1 and 2 and Comparative Examples 1 to 3 by a sputtering method. The upper electrode plate was formed. 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 1-2 and Comparative Examples 1-3 A resistive film type touch panel was prepared.
Evaluation of writing quality, wear resistance, etc. on the touch panel was the same as in Table 1.

4). Production of display device The writing sheets for touch panel pens of Examples 1 and 2 and Comparative Examples 1 to 3 and a commercially available ultra-high-definition liquid crystal display device (pixel density 350 ppi) were bonded to each other through a transparent adhesive layer. Display devices of Examples 1-2 and Comparative Examples 1-3 were produced. In addition, in the case of bonding, the uneven surface side of the writing sheet for touch panel pens was made to face the surface side (the side opposite to the display element) of the display device.
Evaluation of writing quality, wear resistance, etc. in the display device was the same as in Table 1.

  The writing sheet for a touch panel pen, the touch panel, and the display device of the present invention are useful in that the writing quality and the wear resistance can be improved. Moreover, the method for selecting a writing sheet for a touch panel pen according to the present invention can accurately select a writing sheet for a touch panel pen with good writing taste and wear resistance, and efficiently performs product design and quality control of the writing sheet. Useful in that it can.

1: Substrate 2: Concavity and convexity layer 3: Overcoat layer 10: Writing sheet for touch panel pen 20: Transparent adhesive layer 30: Black plate 100: Sample 200: Transparent substrate 300: Conductive film 400: Spacer 500: X-axis electrode 600 : Y-axis electrode 700: Insulator layer 1000: Touch panel

Claims (8)

A writing sheet for a touch panel, wherein at least one surface is an uneven surface, and the uneven surface satisfies the following conditions 1-1 and 1-2.
<Condition 1-1>
A sample in which a black plate is bonded to the surface of the writing sheet for touch panel opposite to the uneven surface through a transparent adhesive layer is prepared. Visible light is irradiated at an angle of +15 degrees from the normal toward the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the angle of −15 degrees from the normal, which is the normal reflection direction of visible light, is set to a reference angle (0 degree), and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. The angle that is the positive direction side angle from the reference angle and first reaches the reflection intensity that is ½ or less of the reflection intensity of the reference angle is + α ₁₅ , the angle that is the negative direction side from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _15. The absolute value of-.alpha. _15, the average of the + alpha ₁₅ upon the alpha _15, shows the relationship 4.5 ° ≦ alpha _15.
<Condition 1-2>
Visible light is irradiated at an angle of +75 degrees from the normal to the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the angle of −75 degrees from the normal, which is the normal reflection direction of the visible light, is set to a reference angle (0 degree), and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. An angle that is a plus direction side angle from the reference angle and first reaches a reflection intensity that is ½ or less of a reflection intensity of the reference angle is + α ₇₅ , an angle that is a minus direction side angle from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _75. The absolute value of-.alpha. _75, the average of the + alpha ₇₅ upon the alpha _75, and alpha ₇₅ and the alpha ₁₅ indicates the relationship between α ₁₅ / α ₇₅ ≦ 4.5.   The writing sheet for a touch panel according to claim 1, wherein the haze of JIS K7136: 2000 is 25.0% or more.   The writing sheet for a touch panel according to claim 1 or 2, wherein a contact angle of pure water on the uneven surface is 94 degrees or more.   The writing sheet for a touch panel according to any one of claims 1 to 3, wherein a contact angle of hexadecane on the uneven surface is 40 degrees or more.   The writing sheet for a touch panel according to any one of claims 1 to 4, wherein the surface has an overcoat layer having a refractive index of 1.45 or less, and the surface on the overcoat layer side is the uneven surface.   It is a touch panel which has a sheet | seat on the surface, Comprising: The touch panel arrange | positioned as the said sheet | seat so that the said uneven | corrugated surface of the writing sheet for touch-panel pens of any one of Claims 1-5 may face the surface of a touch panel.   A display device having a touch panel on a display element, wherein the touch panel is the touch panel according to claim 6. A method for selecting a writing sheet for a touch panel pen, wherein at least one surface is an uneven surface, and the uneven surface satisfies the following conditions 1-1 and 1-2 as a writing sheet for a touch panel.
<Condition 1-1>
A sample in which a black plate is bonded to the surface of the writing sheet for touch panel opposite to the uneven surface through a transparent adhesive layer is prepared. Visible light is irradiated at an angle of +15 degrees from the normal toward the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the direction of −15 degrees from the normal, which is the normal reflection direction of the visible light, is set to the reference angle (0 degree), and the reflection intensity in the direction of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. The angle that is the positive direction side angle from the reference angle and first reaches the reflection intensity that is ½ or less of the reflection intensity of the reference angle is + α ₁₅ , the angle that is the negative direction side from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _15. The absolute value of-.alpha. _15, the average of the + alpha ₁₅ upon the alpha _15, shows the relationship 4.5 ° ≦ alpha _15.
<Condition 1-2>
Visible light is irradiated at an angle of +75 degrees from the normal to the uneven surface side of the sample, and the reflection intensity of the reflected light is measured. In the measurement of the reflection intensity, the angle of −75 degrees from the normal, which is the normal reflection direction of the visible light, is set to a reference angle (0 degree), and the reflection intensity in the range of −12 degrees to +12 degrees including the reference angle is 1 degree. Measure every time. An angle that is a plus direction side angle from the reference angle and first reaches a reflection intensity that is ½ or less of a reflection intensity of the reference angle is + α ₇₅ , an angle that is a minus direction side angle from the reference angle, and the angle to reach the first reflection intensity of 1/2 or less of the reflection intensity and-.alpha. _75. The absolute value of-.alpha. _75, the average of the + alpha ₇₅ upon the alpha _75, and alpha ₇₅ and the alpha ₁₅ indicates the relationship between α ₁₅ / α ₇₅ ≦ 4.5.