JP2023038265A - Transparent electroconductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent electroconductive film that exhibits pleasant operability and exceptional pen sliding durability when used in a touch panel.

SOLUTION: A transparent electroconductive film has a transparent electroconductive membrane of an indium-tin composite oxide layered on at least one side of a biaxially-oriented transparent PET film substrate. A curable resin layer including UV-curable resin and one or more particles selected from inorganic particles and organic particles is formed on at least one side of the laminate. The curable resin layer has a thickness of 0.1-15 μm.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention provides a transparent conductive film obtained by laminating a transparent conductive film of an indium-tin composite oxide on a transparent plastic film substrate, and in particular, when used in a resistive touch panel, it provides light operability and excellent pen sliding. The present invention relates to a durable transparent conductive film.

Transparent conductive films, which are made by laminating a transparent and low-resistance thin film on a transparent plastic substrate, are used in applications that make use of their conductivity, such as flat panel displays such as liquid crystal displays and electroluminescence (EL) displays. It is widely used in the electrical and electronic fields as a transparent electrode for touch panels, etc.

A resistive touch panel is a combination of a fixed electrode made by coating a transparent conductive thin film on a glass or plastic substrate and a movable electrode (= film electrode) made by coating a transparent conductive thin film on a plastic film. It is used overlaid on top. Pressing the film electrode with a finger or a pen to bring the transparent conductive thin films of the fixed electrode and the film electrode into contact with each other serves as an input for recognizing the position of the touch panel. Especially when inputting with a pen, pen sliding durability is required.
In addition, since capacitive touch panels have become common in recent years, there is also a demand for resistive touch panels that can be input even with a light touch in the same manner as capacitive touch panels. For example, it is considered that people who have weak finger pressing force or weak writing pressure due to age, illness, or other reasons strongly desire to be able to input even with a light touch.
However, with a resistive touch panel, a certain amount of input load is required to press the film electrode with a finger or pen to bring the transparent conductive thin films of the fixed electrode and the film electrode into contact with each other. There is no such light operation feeling. In order to solve these problems, a transparent conductive film having light operability is desired.

Japanese Patent Application Laid-Open No. 2004-071171

A conventional transparent conductive film disclosed in Patent Document 1 attempts to improve pen sliding durability by controlling the crystallinity of an indium-tin composite oxide. However, conventional transparent conductive films had insufficient operability when subjected to an input load test described later.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transparent conductive film having light operability and excellent pen sliding durability in view of the conventional problems described above.

The present invention has been made in view of the above circumstances, and the transparent conductive film of the present invention, which has solved the above problems, has the following configuration.
[1] A transparent conductive film of indium-tin composite oxide is laminated on at least one side of a biaxially oriented transparent PET film substrate,
A curable resin layer containing an ultraviolet curable resin and one or more particles selected from inorganic particles and organic particles is formed on at least one side of the laminate,
A transparent conductive film, wherein the curable resin layer has a thickness of 0.1 to 15 μm.
[2] The transparent conductive film according to [1], wherein the curable resin layer is provided between the transparent conductive film and the biaxially oriented transparent PET film substrate.
[3] The transparent conductive film according to [1] or [2], wherein the transparent conductive film has a thickness of 10 nm or more and 100 nm or less.
[4] The transparent conductive film according to any one of [1] to [3], wherein the concentration of tin oxide contained in the transparent conductive film is 0.5% by mass or more and 40% by mass or less.
[5] The transparent conductive film according to any one of [1] to [4], further comprising a functional layer on the side of the biaxially oriented transparent PET film base opposite to the transparent conductive film.
[6] The transparent conductive film according to any one of [1] to [5], which has an easily adhesive layer on at least one side of the biaxially oriented transparent PET film substrate.
[7] The easily adhesive layer is positioned at least one between the biaxially oriented transparent PET film substrate and the curable resin layer, or between the biaxially oriented transparent PET film substrate and the functional layer. The transparent conductive film according to [6], which is arranged in
[8] In the adhesion test according to JIS K5600-5-6:1999 on the surface of the transparent conductive film, the residual area ratio of the transparent conductive film is 95% or more, [1] to [7]. The transparent conductive film according to any one.

Moreover, the transparent conductive film of the present invention has the following structure.
1. A transparent conductive film in which a transparent conductive film of indium-tin composite oxide is laminated on at least one surface side of a transparent plastic film substrate,
A transparent conductive film having an input starting load of 3 g or more and 15 g or less in the following input load test.
(Input load test method)
A transparent conductive film (size: 220 mm × 135 mm) is used as one panel plate, and an indium-tin composite oxide thin film having a thickness of 20 nm is formed by sputtering on a glass substrate (size: 232 mm × 151 mm) as the other panel plate. (Tin oxide content: 10% by mass) A transparent conductive thin film A is used.
On the side of the transparent conductive thin film A of the glass substrate with an indium-tin composite oxide thin film, hereinafter also referred to as ITO glass, epoxy resin (length 60 μm × width 60 μm × height 5 μm) was applied as dot spacers in a square grid pattern with a 4 mm pitch. to be placed.
Next, a double-sided tape (thickness: 105 μm, width: 6 mm) is attached to the transparent conductive thin film A side of the ITO glass so as to form a rectangle of 190 mm×135 mm starting from one of the four corners of the ITO glass.
Next, the transparent conductive film B side of the transparent conductive film is pasted on the double-sided tape pasted on the ITO glass, and the transparent conductive thin film A and the transparent conductive film B are laminated so as to face each other.
At this time, one short side of the transparent conductive film protrudes from the ITO glass.
Next, the ITO glass and the transparent conductive film are connected with a tester.
Next, a load is applied from the transparent conductive film side with a polyacetal pen (tip shape: 0.8 mmR), and the load value when the resistance value measured by the tester stabilizes is taken as the input start load.
The position where the load is applied with the pen is the central area surrounded by the four dot spacers, and the average value of the input start load at the three points is calculated.
For example, it is preferable to measure the input start load at arbitrary three points at a distance of 50 mm or more from the double-sided tape and take the average value. Also, the decimal point may be rounded off.
Also, the position where the load is applied by the pen is the center area of the four dot spacers as shown in FIG. In FIG. 6, each symbol indicates the ITO glass 10, the dot spacer 11, and the position 12 where the load is applied by the pen.
2. The bending resistance of the film bending resistance test below is 0.23 N cm or more and 0.90 N cm or less, and the following average maximum peak height of the conductive surface of the transparent conductive film is the following formula (2-1 ) and the above transparent conductive film satisfying formula (2-2).
(Film bending resistance test method)
A test piece of 20 mm×250 mm is taken from the transparent conductive film, and the test piece is placed on a horizontal platform with a smooth surface so that the transparent conductive layer faces upward. At this time, only the 20 mm×20 mm portion of the test piece is placed on the horizontal table, and the 20 mm×230 mm portion is placed outside the horizontal table. Also, a weight is placed on a 20 mm×20 mm portion of the test piece. At this time, the weight and size of the weight are selected so that there is no gap between the test piece and the horizontal table.
Next, read the difference between the height of the horizontal stage and the height of the leading edge of the film, hereinafter .delta., on the scale. Next, the bending resistance is calculated by substituting numerical values into the following equation (1).
Formula (1) (g×a×b×L ⁴ )/8δ (N cm)
g = gravitational acceleration, a = length of the short side of the test piece, b = specific gravity of the test piece, L = length of the test piece, δ = difference between the height of the horizontal stage and the height of the tip of the film

(Average maximum peak height evaluation)
The average maximum peak height is the average of the maximum peak heights at five points. As for how to select five points, an arbitrary one point A is first selected. Next, two points in total, one point each 1 cm upstream and downstream of A in the longitudinal (MD) direction of the film, are selected. Next, two points in total, one point on each side of 1 cm in the width (TD) direction of the film with respect to A, are selected. The maximum peak height is specified in ISO 25178, and the three-dimensional surface profile measuring device Vertscan (manufactured by Ryoka Systems Co., Ltd., R5500H-M100 (measurement conditions: wave mode, measurement wavelength 560 nm, objective lens 10 times)) was used to obtain the maximum peak height. Values less than 1 nm were rounded off.

Formula (2-1) Average maximum peak height (μm) ≥ 4.7 × bending resistance -1.8
Formula (2-2) 0.005 (μm) ≤ average maximum peak height (μm) ≤ 12.000 (μm)
3. The maximum value of the maximum peak height in the average maximum peak height evaluation is more than 1.0 times and 1.4 times or less than the average maximum peak height, and
The above transparent conductive film, wherein the minimum value of the maximum peak height in the average maximum peak height evaluation is 0.6 to 1.0 times the average maximum peak height.
4. The above transparent conductive film, wherein the transparent conductive film has a thickness of 10 to 100 nm.
5. The above transparent conductive film, wherein the concentration of tin oxide contained in the transparent conductive film is 0.5 to 40% by mass.
6. Having a curable resin layer between the transparent conductive film and the transparent plastic film substrate,
The above transparent conductive film, further comprising a functional layer on the opposite side of the transparent plastic substrate to the transparent conductive film.
7. The above transparent conductive film having an easy-adhesion layer on at least one side of the transparent plastic film substrate.
8. The above-mentioned transparent conductive film, wherein the easy-adhesion layer is arranged at least one position between the transparent plastic film substrate and the curable resin layer or between the transparent plastic substrate and the functional layer.
9. The above-mentioned transparent conductive film, wherein the ON resistance of the transparent conductive film of the transparent conductive film is 10 kΩ or less in the following pen sliding durability test.
(Pen sliding durability test)
A transparent conductive film is used as one panel plate, and the other panel plate is a transparent conductive film made of an indium-tin composite oxide thin film (tin oxide content: 10% by mass) having a thickness of 20 nm on a glass substrate by sputtering. A thin film is used. A touch panel was produced by arranging these two panel plates so that the transparent conductive thin films faced each other with epoxy beads having a diameter of 30 μm interposed therebetween. Next, a linear sliding test of 50,000 reciprocations is performed on the touch panel by applying a load of 2.5 N to a pen made of polyacetal (tip shape: 0.8 mmR). The sliding distance at this time is 30 mm, and the sliding speed is 180 mm/sec. After this sliding durability test, the ON resistance (resistance value when the movable electrode (film electrode) and the fixed electrode are in contact) is measured when the sliding portion is pressed with a pen load of 0.8N.
10. The transparent conductive film having a residual area ratio of 95% or more in an adhesion test according to JIS K5600-5-6:1999 on the surface of the transparent conductive film.

ADVANTAGE OF THE INVENTION According to this invention, provision of the transparent conductive film which has light operability and excellent pen sliding durability is attained.

FIG. 2 is a schematic diagram for explaining the position of a center roll of an example of a sputtering apparatus preferably used in the present invention; 1 is a schematic diagram showing a configuration in one embodiment of the present invention; FIG. 1 is a schematic diagram showing a configuration in one embodiment of the present invention; FIG. 1 is a schematic diagram showing a configuration in one embodiment of the present invention; FIG. 1 is a schematic diagram showing a configuration in one embodiment of the present invention; FIG. It is a schematic diagram which illustrates the measurement position in an input load test method.

The transparent conductive film of the present invention is a transparent conductive film in which a transparent conductive film of indium-tin composite oxide is laminated on at least one side of a transparent plastic film substrate, and is subjected to the following input load test. The transparent conductive film has an input starting load of 3 g or more and 15 g or less.
(Input load test method)
A transparent conductive film (size: 220 mm × 135 mm) is used as one panel plate, and an indium-tin composite oxide thin film having a thickness of 20 nm is formed by sputtering on a glass substrate (size: 232 mm × 151 mm) as the other panel plate. (Tin oxide content: 10% by mass) A transparent conductive thin film A is used.
On the side of the transparent conductive thin film A of the glass substrate with an indium-tin composite oxide thin film, hereinafter also referred to as ITO glass, epoxy resin (length 60 μm × width 60 μm × height 5 μm) was applied as dot spacers in a square grid pattern with a 4 mm pitch. to be placed.
Next, a double-sided tape (thickness: 105 μm, width: 6 mm) is attached to the transparent conductive thin film A side of the ITO glass so as to form a rectangle of 190 mm×135 mm starting from one of the four corners of the ITO glass.
Next, the transparent conductive film B side of the transparent conductive film is pasted on the double-sided tape pasted on the ITO glass, and the transparent conductive thin film A and the transparent conductive film B are laminated so as to face each other.
At this time, one short side of the transparent conductive film protrudes from the ITO glass.
Next, the ITO glass and the transparent conductive film are connected with a tester.
Next, a load is applied from the transparent conductive film side with a polyacetal pen (tip shape: 0.8 mmR), and the load value when the resistance value measured by the tester stabilizes is taken as the input start load.
The position where the load is applied with the pen is the central area surrounded by the four dot spacers, and the average value of the input start load at the three points is calculated.
For example, it is preferable to measure the input start load at arbitrary three points at a distance of 50 mm or more from the double-sided tape and take the average value. Also, the decimal point may be rounded off.
Also, the position where the load is applied by the pen is the center area of the four dot spacers as shown in FIG.

Here, in the present invention, when measuring with a tester, it is preferable that the resistance value fluctuates within a range of ±5%, for example, for determination of "stable resistance value" depending on external factors such as the environment to be measured. .

The present invention having such characteristics can provide a transparent conductive film having light operability and excellent pen sliding durability. The obtained transparent conductive film is extremely useful for applications such as resistive touch panels.

The transparent conductive film of the present invention has light operability. In the transparent conductive film of indium-tin composite oxide, which has excellent operability, the maximum peak height of the surface on the transparent conductive film side is in an appropriate range with respect to the height of the dot spacers in the ITO glass for touch panels, It was found that the film has a low bending resistance in a bending resistance test, and that the tin oxide concentration of the transparent conductive film is close to that of the ITO glass for touch panels.

Light operability will be explained. Light operability means that input can be made to the resistive touch panel even if the transparent conductive film side of the resistive touch panel is pressed with a pen or finger with a light force. Light operability was evaluated by an input load test in the present invention. In the present invention, if the input starting load of the transparent conductive film in the input load test is 3 g or more and 15 g or less, it has light operability.
The present invention having such an input start load can be applied to people who have a weak finger pressing force due to age, illness, or other reasons, or who have a weak writing pressure, even if it is a transparent conductive film used for applications such as a resistive touch panel. A weak person can input by touching lightly.
An input start load of 15 g or less is preferable because it provides light operability. More preferably, it is 13 g or less. More preferably, it is 11 g or less. On the other hand, if the input start load is 3 g or more, an erroneous reaction of the touch panel can be prevented, which is preferable. More preferably 5 g or more, still more preferably 8 g or more.

In the present invention, the bending resistance of the following film bending resistance test is 0.23 N cm or more and 0.90 N cm or less, and the following average maximum crest height of the transparent conductive film side surface of the transparent conductive film It is preferred that the following formulas (2-1) and (2-2) be satisfied.
First, the bending resistance by the film bending resistance test will be explained. In the film bending resistance test, the test piece is placed on a smooth horizontal table with the transparent conductive layer facing up. This is to align the direction in which the transparent conductive film is deformed when the transparent conductive film is pressed from the non-transparent conductive layer side with a pen or a finger. Even with the same transparent conductive film, the bending resistance value changes depending on whether the transparent conductive layer is on the top or the bottom in the film bending resistance test, so care must be taken when evaluating.
Further, when a curable resin layer is arranged between the transparent plastic substrate and the transparent conductive film, the thickness and hardness of the curable resin layer also affect the bending resistance. Further, when curable resin layers are arranged on both sides of the transparent plastic base material, the balance of thickness and hardness of the curable resin layers on each side affects the bending resistance.

If the bending resistance of the transparent conductive film is 0.23 N cm or more, the transparent conductive film is unlikely to be deformed when the transparent conductive film is unintentionally touched with a very light force. Electrical contact between the transparent conductive film of the film and the transparent conductive film of the ITO glass for a touch panel is unlikely to occur, and erroneous input can be easily prevented, which is preferable. Moreover, it is preferable because it is excellent in pen sliding durability. More preferably, it is 0.27 N·cm or more. More preferably, it is 0.30 N·cm or more.
On the other hand, if the bending resistance of the transparent conductive film is 0.90 N cm or less, the transparent conductive film is easily deformed even when pressed with a pen or finger from the transparent conductive film side with a low input load. Since the transparent conductive film of the conductive film and the transparent conductive film of the ITO glass are easily brought into electrical contact with each other, it is preferable because of light operability. More preferably, it is 0.80 N·cm or less. More preferably, it is 0.70 N·cm or less. Particularly preferably, it is 0.60 N·cm or less.

(Film bending resistance test method)
A test piece of 20 mm×250 mm is taken from the transparent conductive film, and the test piece is placed on a horizontal platform with a smooth surface so that the transparent conductive layer faces upward. At this time, only the 20 mm×20 mm portion of the test piece is placed on the horizontal table, and the 20 mm×230 mm portion is placed outside the horizontal table. Also, a weight is placed on a 20 mm×20 mm portion of the test piece. At this time, the weight and size of the weight are selected so that there is no gap between the test piece and the horizontal table.
Next, read the difference (=.delta.) between the height of the horizontal stage and the height of the leading edge of the film on the scale. Next, the bending resistance is calculated by substituting numerical values into the following equation (1).
Formula (1) (g×a×b×L ⁴ )/8δ (N cm)
g = gravitational acceleration, a = length of the short side of the test piece, b = specific gravity of the test piece, L = length of the test piece, δ = difference between the height of the horizontal stage and the height of the tip of the film

In the present invention, when the film bending resistance test is performed, the bending resistance of the film bending resistance test is 0.23 N cm or more and 0.90 N cm or less, and the transparent conductive film side of the transparent conductive film It is preferable that the following average maximum peak height of the surface satisfies the following formulas (2-1) and (2-2).
(Average maximum peak height evaluation)
The average maximum peak height is the average of the maximum peak heights at five points. As for how to select five points, an arbitrary one point A is first selected. Next, two points in total, one point each 1 cm upstream and downstream of A in the longitudinal (MD) direction of the film, are selected. Next, two points in total, one point on each side of 1 cm in the width (TD) direction of the film with respect to A, are selected. The maximum peak height is specified in ISO 25178, and the three-dimensional surface profile measuring device Vertscan (manufactured by Ryoka Systems Co., Ltd., R5500H-M100 (measurement conditions: wave mode, measurement wavelength 560 nm, objective lens 10 times)) was used to obtain the maximum peak height. Values less than 1 nm were rounded off.

Formula (2-1) Average maximum peak height ≥ 4.7 x bending resistance -1.8
Formula (2-2) 0.005 (μm) ≤ average maximum peak height (μm) ≤ 12.000 (μm)

If the maximum peak height of the surface on the transparent conductive film side satisfies the formulas (2-1) and (2-2), even if the transparent conductive film side is pressed with a pen or a finger with a low input load, the transparent conductive film will remain flat. Since the transparent conductive film arranged on the projection on the transparent conductive film side can be electrically contacted with the transparent conductive film of the ITO glass for the touch panel, it is preferable because of light operability.
More preferably, the y-intercept of formula (2-1), ie, the value indicated by "-1.8" in formula (2-1) above, is -1.7 or more. More preferably, the y-intercept of formula (2-1) is -1.6 or more.
Moreover, when the average maximum peak height is 0.005 (μm) or more, the transparent conductive film can be wound into a roll without any trouble, which is preferable. More preferably, it is 0.010 (μm) or more. More preferably, it is 0.020 (μm) or more. In addition, if the average maximum peak height is 12.000 (μm) or less, the transparent conductive film disposed on the transparent conductive film side protrusion of the transparent conductive film and the transparent conductive film of the ITO glass for touch panel are not intended. Since electrical contact is unlikely to occur, it is easy to prevent erroneous input, which is preferable. More preferably, it is 11.000 (μm) or less. More preferably, it is 10.000 (μm) or less. From the above, it was found that a moderate balance between bending resistance and average maximum peak height satisfies light operability.

The maximum value of the maximum peak height in the average maximum peak height evaluation described below in the present invention is more than 1.0 times and 1.4 times or less than the average maximum peak height, and
The minimum value of the maximum peak height in the average maximum peak height evaluation is 0.6 times or more and 1.0 times or less of the average maximum peak height. Within the above range, the variation in input start load is less than ±5%, which is preferable.
If the minimum value of the maximum peak height in the average maximum peak height evaluation is 0.6 times or more of the average maximum peak height, the in-plane of the high protrusions on the transparent conductive film side of the transparent conductive film that is involved in light operability Since the distribution is uniform, it is possible to perform input on the touch panel with the same input load at any position when pressing from the transparent conductive film side with a pen or finger, which is preferable. More preferably, it is 0.7 times or more. More preferably, it is 0.8 times or more.
On the other hand, if the maximum value of the maximum peak height in the average maximum peak height evaluation is 1.4 times or less than the average maximum peak height, the transparent conductive film side of the transparent conductive film involved in light operability is a high protrusion. Since the in-plane distribution of is uniform, when pressing from the transparent conductive film side with a pen or a finger, it is possible to input on the touch panel with the same input load at any place, which is preferable. More preferably, it is 1.3 times or less. More preferably, it is 1.2 times or less.

(Average maximum peak height evaluation)
The average maximum peak height is the average of the maximum peak heights at five points. As for how to select five points, an arbitrary one point A is first selected. Next, two points in total, one point each 1 cm upstream and downstream of A in the longitudinal (MD) direction of the film, are selected. Next, two points in total, one point on each side of 1 cm in the width (TD) direction of the film with respect to A, are selected. The maximum peak height is specified in ISO 25178, and the three-dimensional surface profile measuring device Vertscan (manufactured by Ryoka Systems Co., Ltd., R5500H-M100 (measurement conditions: wave mode, measurement wavelength 560 nm, objective lens 10 times)) was used to obtain the maximum peak height. Values less than 1 nm were rounded off.

The transparent conductive film in the present invention is made of indium-tin composite oxide. The transparent conductive film of the present invention preferably has a surface resistance of 50 to 900 Ω/□, more preferably 50 to 700 Ω/□. Further, the transparent conductive film of the present invention preferably has a total light transmittance of 70 to 95%.

In the present invention, the thickness of the transparent conductive film is preferably 10 nm or more and 100 nm or less. When the thickness of the transparent conductive film is 10 nm or more, the transparent conductive film adheres entirely to the transparent film substrate or the curable resin layer, and the film quality of the transparent conductive film is stabilized, resulting in a stable surface resistance value. It is preferable because it falls within a preferable range. More preferably, the thickness of the transparent conductive film is 13 nm or more, more preferably 16 nm or more. Further, when the thickness of the transparent conductive film is 100 nm or less, the crystal grain size and crystallinity of the transparent conductive film are appropriate, and the total light transmittance is at a practical level, which is preferable. It is more preferably 50 nm or less, still more preferably 30 nm or less, and particularly preferably 25 nm or less.

In the present invention, the tin oxide concentration contained in the transparent conductive film of the transparent conductive film is preferably 0.5 to 40% by mass. The closer the concentration of tin oxide contained in the transparent conductive film of the transparent conductive film to the concentration of tin oxide contained in the ITO glass for touch panel, the more electrically the transparent conductive film of the transparent conductive film and the transparent conductive film of the ITO glass become. It was found that it has light operability because it becomes easy to contact with. The concentration of tin oxide contained in ITO glass for touch panels is generally 10% by mass.
In the present invention, if the difference between the tin oxide concentration contained in the transparent conductive film of the transparent conductive film and the tin oxide concentration contained in the ITO glass for touch panel is 30% by mass or less, the transparent conductive film of the transparent conductive film and Since the transparent conductive film of the ITO glass is easy to electrically contact, it is preferable because it has light operability.
The concentration of tin oxide contained in ITO glass for touch panels is often 10% by mass. Therefore, in the present invention, the tin oxide concentration of the transparent conductive film is preferably 40% by mass or less. More preferably, it is 25% by mass or less. More preferably, it is 20% by mass or less. Particularly preferably, it is 2% by mass or more and 18% by mass. Further, when the tin oxide content is 0.5% by mass or more, the surface resistance of the transparent conductive film is at a practical level, which is preferable. More preferably, the content of tin oxide is 1% by mass or more, and particularly preferably 2% by mass or more.

In one aspect, the transparent conductive film in the invention has a curable resin layer between the transparent conductive film and the transparent plastic film substrate.
Furthermore, it is preferable to have a functional layer on the opposite side of the transparent plastic substrate to the transparent conductive film.
As shown in a configuration example in FIG. 2, it can have a transparent conductive film 5, a curable resin layer 6, a transparent plastic film substrate 7, and a functional layer 8 in this order.
If the transparent conductive film is heated in the touch panel processing step and the monomers and oligomers generated from the transparent plastic film base are precipitated on the transparent conductive film at that time, there is a risk of impairing the smooth operability of the touch panel.
Therefore, the presence of the curable resin layer between the transparent conductive film and the transparent plastic film substrate is preferable because it can block the precipitation of monomers and oligomers on the transparent conductive film.

In addition, since the monomers and oligomers deposited from the transparent plastic substrate may reduce the visibility of the transparent conductive film, it is preferable that the transparent plastic film substrate has a curable resin layer and a functional layer.
Moreover, by having a curable resin layer and a functional layer, the bending resistance of the transparent conductive film can be adjusted to a more preferable range in the present invention.
The curable resin layer and functional layer according to the present invention can more effectively exhibit various properties such as pen sliding durability. In particular, in the present invention, by having a curable resin layer and a functional layer, the bending resistance of the transparent conductive film of the present invention can be adjusted, and the input start load can be adjusted within a predetermined range. , excellent visibility can be achieved.
Although it should not be interpreted as being limited to a specific theory, in the present invention, by having both a curable resin layer and a functional layer, the resistive touch panel exhibits a light operability and more accurate input performance. be able to.
In addition, by having a curable resin layer on the transparent plastic film substrate, in addition to increasing the adhesive strength of the transparent conductive film, it is possible to disperse the force applied to the transparent conductive film. It is preferable because it suppresses cracks, peeling, abrasion, etc. of the conductive film. In addition, it is preferable that the transparent plastic film base material has a functional layer, because it is less likely to be scratched due to input with a pen or the like.

In one embodiment, the transparent conductive film of the present invention has an easy-adhesion layer laminated on at least one side of a transparent plastic film substrate.
For example, the transparent conductive film in the present invention may contain an easy-adhesion layer either or both between the transparent plastic film substrate and the curable resin layer or between the transparent plastic film substrate and the functional layer. is preferred. 3, 4, and 5 show configuration examples. In these figures, an easy adhesion layer 9 is arranged. Other symbols have the same meaning as in FIG.
The easy-adhesion layer allows the curable resin layer and the functional layer to firmly adhere to the transparent plastic film substrate, so that peeling of the curable resin layer and the functional layer due to external force can be more effectively suppressed, which is preferable.

The transparent conductive film of the present invention is a transparent conductive film in which a transparent conductive film of indium-tin composite oxide is laminated on at least one surface of a transparent plastic film substrate, and has the following pen sliding durability: It is preferable that the ON resistance of the transparent conductive film of the transparent conductive film by the test is 10 kΩ or less.
(Pen sliding durability test)
Using the transparent conductive film according to the present invention as one panel plate, and as the other panel plate, an indium-tin composite oxide thin film having a thickness of 20 nm (tin oxide content: 10% by mass) was formed on a glass substrate by a sputtering method. A transparent conductive thin film consisting of was used. The two panel plates were arranged so that the transparent conductive thin films faced each other with epoxy beads having a diameter of 30 μm interposed therebetween, and the panel plate on the film side and the panel plate on the glass side were attached with double-sided tape having a thickness of 170 μm. , to fabricate a touch panel. Next, a linear sliding test of 50,000 reciprocations was performed on the touch panel by applying a load of 2.5 N to a pen made of polyacetal (tip shape: 0.8 mmR). In this test, a pen load is applied to the surface of the transparent conductive film according to the present invention. The sliding distance at this time was 30 mm, and the sliding speed was 180 mm/sec. After this sliding durability test, the ON resistance (the resistance value when the movable electrode (film electrode) and the fixed electrode are in contact) was measured when the sliding portion was pressed with a pen load of 0.8N.

In the present invention, if the ON resistance of the transparent conductive film of the transparent conductive film in the pen sliding durability test is 10 kΩ or less, cracks, peeling, abrasion, etc. of the transparent conductive film can be suppressed even if continuous input is made with a pen on the touch panel. preferred because it is In one aspect, the ON resistance may be 9.5 kΩ or less, more preferably 5 kΩ or less. For example, the ON resistance is 3 kΩ or less, may be 1.5 kΩ or less, and preferably is 1 kΩ or less.
The ON resistance is, for example, 5 kΩ or more, may be 3 kΩ or more, and is preferably 0 kΩ or more.
When the ON resistance is within such a range, cracks, peeling, abrasion, etc. of the transparent conductive film can be suppressed even when continuous input is made to the touch panel with a pen.
In one aspect, these upper and lower limits may be combined as appropriate.

For example, the transparent conductive film of the present invention has a remaining area ratio of the transparent conductive film of 95% or more in an adhesion test according to JIS K5600-5-6:1999 on the surface of the transparent conductive film. The transparent conductive film in the present invention preferably has a residual area ratio of 95% or more of the transparent conductive film even when an adhesion test (JIS K5600-5-6: 1999) is performed on the transparent conductive film surface. Preferably, the peeling area of the transparent conductive film is 99% or more, and particularly preferably 99.5% or more. When the residual area ratio of the transparent conductive film is within the above range in the adhesion test, the transparent conductive film is in contact with the transparent conductive film, such as a transparent plastic film substrate or a curable resin layer. Because it is in close contact with the touch panel, cracks, peeling, and abrasion of the transparent conductive film are suppressed even if the pen is continuously used to input data to the touch panel. On the other hand, it is preferable because cracks, peeling, etc. can be suppressed.

For example, the transparent conductive film of the present invention has a residual area ratio of the functional layer of 95% or more in an adhesion test according to JIS K5600-5-6:1999 on the surface of the functional layer. The transparent conductive film in the present invention preferably has a residual area ratio of 95% or more on the functional layer surface even when an adhesion test (JIS K5600-5-6: 1999) is performed on the functional layer surface, and more preferably, The residual area ratio of the functional layer surface is 99% or more, particularly preferably 99.5% or more.
The transparent conductive film, whose functional layer does not peel off in the adhesion test, adheres to the transparent plastic film substrate and the functional layer. Defects in appearance are suppressed, and even if a force stronger than expected for normal use is applied, the functional layer mitigates the strong force, so that the transparent conductive film can be prevented from cracking, peeling, etc., which is preferable.

The production method for obtaining the transparent conductive film of the present invention is not particularly limited, but for example, the following production methods can be preferably exemplified.
A sputtering method is preferably used as a method for forming a transparent conductive film of an indium-tin composite oxide on at least one surface of a transparent plastic film substrate. In order to produce a transparent conductive film with high productivity, it is preferable to use a so-called roll-type sputtering apparatus that feeds a film roll and winds up the film in the form of a film roll after film formation. Using a mass flow controller in the film formation atmosphere, flowing inert gas and oxygen gas, and using a sintering target of indium-tin composite oxide, the thickness of the transparent conductive film of indium-tin composite oxide becomes 10 to 100 nm. It can be preferably adopted to form a transparent conductive film on a transparent plastic film by adjusting as follows. In order to improve production efficiency, a plurality of sintering targets of indium-tin composite oxide may be placed in the direction of film flow. In addition, using a mass flow controller in the film forming atmosphere, any hydrogen atom-containing gas (such as hydrogen, ammonia, hydrogen + argon mixed gas, etc.) is not particularly limited as long as it contains hydrogen atoms. However, water is excluded. ) can be passed. If there is a large amount of water in the film formation atmosphere, the film quality of the transparent conductive film deteriorates, resulting in deterioration of the film quality of the transparent conductive film, such as the surface resistance value deviating from the preferable range or the transparent conductive film that is originally crystallized does not crystallize. The amount of water in the deposition atmosphere is also an important factor, as it is known to have an adverse effect. By controlling the central value (the middle value between the maximum value and the minimum value) of the ratio of the water pressure to the inert gas in the film formation atmosphere during sputtering on the film roll to 7.00 × 10 ^-3 or less, transparent conductive It is preferable because deterioration of the film quality of the film can be suppressed. In addition to rotary pumps, turbomolecular pumps, and cryopumps, which are often used as exhaust devices for sputtering machines, to control the amount of moisture in the film deposition atmosphere, the bombardment process described below and the unevenness of the film roll end surface described below are used. It is preferable to attach a protective film having a low water absorption rate to the surface opposite to the surface on which the transparent conductive film is formed, because the amount of water released from the film during the formation of the transparent conductive film is reduced. Moreover, it is preferable to form the transparent conductive film on the transparent plastic film by setting the film temperature at the time of sputtering to 0° C. or lower. The film temperature during film formation is substituted by the set temperature of a temperature controller that adjusts the temperature of the center roll with which the running film is in contact. Here, FIG. 1 shows a schematic diagram of an example of a sputtering apparatus preferably used in the present invention. An indium-tin sputtering target 4 is placed through a chimney 3 , and a thin film of indium-tin composite oxide is deposited and laminated on the surface of the film 1 running on the center roll 2 . The temperature of the center roll 2 is controlled by a temperature controller (not shown). If the film temperature is 0° C. or lower, it is possible to suppress release of impurity gases such as water and organic gases from the film, which deteriorate the film quality of the transparent conductive film, which is preferable. In addition, in order to bring the surface resistance and total light transmittance of the transparent conductive film to a practical level, it is desirable to add oxygen gas during sputtering.

In order to control the water content when forming an indium-tin composite oxide film on a plastic film, it is better to actually observe the water content during film formation than to observe the ultimate vacuum. desirable for two reasons.

The first reason is that when a film is formed on a plastic film by sputtering, the film is heated and moisture is released from the film, so the amount of moisture in the film-forming atmosphere increases, and the ultimate vacuum was measured. It is more accurate to express the moisture content at the time of film formation rather than the ultimate degree of vacuum, since the moisture content increases more than the moisture content at the time of film formation.

The second reason for this is the case of an apparatus into which a large amount of transparent plastic film is fed. In such devices the film is input in the form of film rolls. When the film is rolled and placed in a vacuum chamber, the outer layer of the roll is easy to drain, but the inner layer of the roll is difficult to drain. When the ultimate vacuum is measured, the film roll is stopped, but since the film roll is running during film formation, the inner layer part of the film roll containing a lot of water is unwound, so the moisture in the film formation atmosphere This is because the amount of water increases, and the amount of water increases more than the amount of water when the degree of ultimate vacuum is measured. In the present invention, the control of the water content in the film-forming atmosphere can be preferably handled by observing the ratio of the water pressure to the inert gas in the film-forming atmosphere during sputtering.

Prior to depositing the transparent conductive film, it is desirable to pass the film through a bombardment process. The bombardment process is to generate plasma by applying a voltage to generate a discharge while only an inert gas such as argon gas or a mixed gas of a reactive gas such as oxygen and an inert gas is flowing. . Specifically, it is desirable to bombard the film by RF sputtering with a SUS target or the like. Since the film is exposed to plasma in the bombardment process, water and organic components are released from the film, and the amount of water and organic components released from the film during formation of the transparent conductive film is reduced, resulting in good film quality of the transparent conductive film. It is preferable because In addition, since the layer in contact with the transparent conductive film is activated by the bombardment process, the adhesion of the transparent conductive film is improved, which is desirable because the pen sliding durability is improved.

A film roll for forming a transparent conductive film preferably has a height difference of 10 mm or less between the most convex part and the most concave part on the end surface of the roll. If the thickness is 10 mm or less, water and organic components are less likely to be released from the end surface of the film when the film roll is put into the sputtering apparatus, and the film quality of the transparent conductive film is improved, which is preferable.

In the film (transparent plastic film substrate) on which the transparent conductive film is to be formed, it is desirable to attach a protective film having a low water absorption rate to the surface opposite to the surface on which the transparent conductive film is to be formed. By attaching a protective film having a low water absorption rate, gases such as water are less likely to be released from the film substrate, and the film quality of the transparent conductive film is improved, which is preferable. Polyethylene, polypropylene, cycloolefin and the like are preferable as the base material of the protective film having a low water absorption rate.

In the method of forming a transparent conductive film of crystalline indium-tin composite oxide on at least one surface of a transparent plastic film substrate, it is desirable to introduce oxygen gas during sputtering. When oxygen gas is introduced during sputtering, problems due to lack of oxygen in the transparent conductive film of the indium-tin composite oxide do not occur, and the transparent conductive film has a low surface resistance and a high total light transmittance, which is preferable. Therefore, in order to bring the surface resistance and total light transmittance of the transparent conductive film to a practical level, it is desirable to introduce oxygen gas during sputtering. The total light transmittance of the transparent conductive film of the invention is preferably 70 to 95%.

The transparent conductive film of the present invention is produced by laminating a transparent conductive film of an indium-tin composite oxide on a transparent plastic film substrate, and then heating it at 80 to 200° C. at 0.1 to 0.1 in an oxygen-containing atmosphere. It is desirable to be heat-treated for 12 hours. When the temperature is 80° C. or higher, it is preferable when the crystallinity of the transparent conductive film needs to be enhanced for the purpose of improving pen sliding durability. When the temperature is 200° C. or lower, the flatness of the transparent plastic film is secured, which is preferable.

<Transparent plastic film substrate>
The transparent plastic film substrate used in the present invention is a film obtained by melt-extrusion or solution-extrusion of an organic polymer into a film, and if necessary, stretching in the longitudinal direction and/or the width direction, cooling, and heat setting. and the organic polymers include polyethylene, polypropylene, polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polybutylene terephthalate, nylon 6, nylon 4, nylon 66, nylon 12, polyimide, polyamideimide, polyether Sulfan, polyether ether ketone, polycarbonate, polyarylate, cellulose propionate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyetherimide, polyphenylene sulfide, polyphenylene oxide, polystyrene, syndiotactic polystyrene, norbornene polymer, etc. is mentioned.

Among these organic polymers, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, syndiotactic polystyrene, norbornene-based polymer, polycarbonate, polyarylate and the like are suitable. Further, these organic polymers may be copolymerized with a small amount of monomers of other organic polymers, or may be blended with other organic polymers.

The transparent plastic film substrate used in the present invention may be subjected to surface activation treatment such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, ozone treatment, etc., within the scope not impairing the object of the invention. It may be subjected to a hardening treatment.

In the transparent conductive film of the present invention, the thickness of the transparent plastic film substrate is preferably in the range of 100 µm to 240 µm, more preferably 120 µm to 220 µm. When the thickness of the plastic film is 100 μm or more, the mechanical strength is maintained, and deformation due to pen input when used in a touch panel is small, and pen sliding durability is excellent, which is preferable. On the other hand, when the thickness is 240 μm or less, it is preferable because it maintains light operability when used in a touch panel.

When a curable resin layer is laminated on a transparent plastic film substrate, it is possible to block the precipitation of monomers and oligomers generated from the transparent plastic film substrate onto the transparent conductive film, which is preferable because it does not hinder the light operability of the touch panel. . In addition, since the transparent conductive film strongly adheres to the curable resin layer and the force applied to the transparent conductive film can be dispersed, cracks, peeling, abrasion, etc. is suppressed, which is preferable. In order to improve the adhesion between the transparent plastic film substrate and the curable resin layer, it is preferable to provide an easy-adhesion layer between the transparent plastic film substrate and the curable resin layer.

When the functional layer is laminated on the transparent plastic film substrate, it is possible to block the precipitation of monomers and oligomers generated from the transparent plastic film substrate, which is preferable because it suppresses deterioration of the visibility of the transparent conductive film. In order to adjust the bending resistance of the transparent conductive film, the transparent plastic film substrate preferably has a functional layer. In addition, it is preferable that the transparent plastic film base material has a functional layer, because it is less likely to be scratched due to input with a pen or the like.

In addition, the resin contained in the curable resin layer and the functional layer preferably used in the present invention is not particularly limited as long as it is a resin that is cured by applying energy such as heating, ultraviolet irradiation, electron beam irradiation, etc. Silicone resin, Examples include acrylic resins, methacrylic resins, epoxy resins, melamine resins, polyester resins, urethane resins, and the like. From the viewpoint of productivity, it is preferable to use an ultraviolet curable resin as a main component.
The resin contained in the curable resin layer and the functional layer may be the same resin or different resins.

Such UV-curable resins include, for example, polyfunctional acrylate resins such as acrylic or methacrylic acid esters of polyhydric alcohols, diisocyanates, polyhydric alcohols, and hydroxyalkyl esters of acrylic acid or methacrylic acid. Polyfunctional urethane acrylate resins such as those described above can be mentioned. If necessary, a monofunctional monomer such as vinylpyrrolidone, methyl methacrylate, or styrene can be added to these polyfunctional resins for copolymerization.

Moreover, in order to improve the adhesion between the transparent conductive thin film and the curable resin layer, it is effective to treat the surface of the curable resin layer by the method described below. Specific methods include a discharge treatment method in which glow or corona discharge is applied to increase carbonyl groups, carboxyl groups, and hydroxyl groups, and an acid or alkali treatment method to increase polar groups such as amino groups, hydroxyl groups, and carbonyl groups. A chemical treatment method, etc., to be treated can be mentioned.

UV-curable resins are usually used by adding a photopolymerization initiator. As the photopolymerization initiator, any known compound that absorbs ultraviolet rays and generates radicals can be used without particular limitation. etc. can be mentioned. The amount of the photopolymerization initiator to be added is preferably 1 to 5 parts by mass per 100 parts by mass of the ultraviolet curable resin.

Moreover, in the present invention, the curable resin layer and the functional layer preferably use inorganic particles and organic particles in combination with the curable resin, which is the main component. By dispersing inorganic particles or organic particles in the curable resin, unevenness is formed on the surfaces of the curable resin layer and the functional layer, and surface roughness in a wide area can be improved.
In the present invention, by improving the surface roughness of the curable resin layer, the bending resistance of the transparent conductive film can be adjusted to a more preferable range in the present invention. In addition, various properties such as pen sliding durability, anti-Newton ring properties, and film windability can be more effectively exhibited.
In the present invention, by improving the surface roughness of the functional layer, the bending resistance of the transparent conductive film can be adjusted to a more preferable range in the present invention. In addition, various properties such as film windability, writing comfort with a pen, and finger touch can be more effectively exhibited.

Silica etc. are illustrated as said inorganic particle. Examples of the organic particles include polyester resins, polyolefin resins, polystyrene resins, polyamide resins, and the like. The particles contained in the curable resin layer and the functional layer may be the same particles or different particles.

In addition to inorganic particles and organic particles, it is also preferable to use a resin that is incompatible with the curable resin, in addition to the curable resin that is the main component. By using a small amount of an incompatible resin together with the matrix curable resin, phase separation occurs in the curable resin and the incompatible resin can be dispersed in the form of particles. The dispersed particles of the immiscible resin can form irregularities on the surfaces of the curable resin layer and the functional layer, thereby improving the surface roughness in a wide area.

Examples of non-compatible resins include polyester resins, polyolefin resins, polystyrene resins, polyamide resins, and the like.

Here, as an example, the mixing ratio when inorganic particles are used in the curable resin layer is shown. The amount of the inorganic particles is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 25 parts by mass, and particularly preferably 0.1 to 20 parts by mass per 100 parts by mass of the ultraviolet curable resin. Part by mass or less. When the blending amount of the inorganic particles is 0.1 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the ultraviolet curable resin, the protrusions formed on the surface of the curable resin layer are not too small, and the effective average maximum It is preferable because it can provide a crest height, has light operability to the touch panel, and can maintain the film windability because the transparent conductive film has some surface protrusions. When inorganic particles are used in the curable resin layer, the higher the blending ratio within the above range, the higher the average maximum peak height of the curable resin layer tends to be.
Further, when inorganic particles are used in the curable resin layer, the bending resistance of the transparent conductive film tends to increase when the mixing ratio is higher within the above range.

Here, as an example, the mixing ratio when inorganic particles are used in the functional layer is shown. It is preferable that the amount of the inorganic particles is 0.1 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the ultraviolet curable resin.
When inorganic particles are used in the functional layer, the higher the blending ratio within the above range, the lower the bending resistance of the transparent conductive film. When the blending amount of the inorganic particles is 0.1 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the ultraviolet curable resin, the bending resistance of the transparent conductive film is adjusted to an appropriate value according to the present invention. is possible and preferable. In addition, since surface projections can be formed on the functional layer within a range that does not impair the effects of the present invention, film windability can be maintained, which is preferable.

The UV-curable resin, the photopolymerization initiator, and the resin incompatible with the inorganic particles, organic particles, and UV-curable resin are dissolved in a common solvent to prepare a coating liquid. The solvent to be used is not particularly limited, and examples thereof include alcohol solvents such as ethyl alcohol and isopropyl alcohol, ester solvents such as ethyl acetate and butyl acetate, and dibutyl ether and ethylene glycol monoethyl ether. Ether-based solvents, ketone-based solvents such as methyl isobutyl ketone and cyclohexanone, and aromatic hydrocarbon-based solvents such as toluene, xylene, solvent naphtha, and the like can be used singly or in combination.

The concentration of the resin component (that is, solid content concentration) in the coating liquid can be appropriately selected in consideration of the viscosity and the like according to the coating method. For example, the ratio of the total amount of the UV-curable resin, the photopolymerization initiator and the high-molecular-weight polyester resin in the coating liquid is usually 20 to 80% by mass. The higher the concentration of the resin component, the higher the average maximum peak height of the curable resin layer. If necessary, other known additives such as a silicone leveling agent may be added to the coating liquid.

In the present invention, the prepared coating liquid is coated on a transparent plastic film substrate. The coating method is not particularly limited, and conventionally known methods such as bar coating, gravure coating and reverse coating can be used.

In the coating liquid coated, the solvent is removed by evaporation in the next drying step. In this step, the high-molecular-weight polyester resin uniformly dissolved in the coating solution is precipitated in the UV-curable resin as particles. After the coating film is dried, the plastic film is irradiated with ultraviolet rays to crosslink and cure the ultraviolet curable resin to form a curable resin layer and a functional layer. In this curing step, the particles of the high-molecular-weight polyester resin are fixed in the hard coat layer, and projections are formed on the surfaces of the curable resin layer and the functional layer to improve surface roughness over a wide area.

Moreover, the thickness of the curable resin layer is preferably in the range of 0.1 μm or more and 15 μm or less. It is more preferably in the range of 0.5 μm or more and 10 μm or less, and particularly preferably in the range of 1 μm or more and 8 μm or less. When the thickness of the curable resin layer is 0.1 μm or more, sufficient projections are formed, which is preferable. On the other hand, if the thickness is 15 μm or less, the productivity is good and it is preferable. In addition, when the curable resin layer is thick, it tends to increase the bending resistance of the transparent conductive film.

Moreover, the thickness of the functional layer is preferably in the range of 0.1 μm or more and 15 μm or less. It is more preferably in the range of 0.5 μm or more and 15 μm or less, and particularly preferably in the range of 1 μm or more and 10 μm. A thick functional layer tends to lower the bending resistance of the transparent conductive film. When the thickness of the functional layer is 0.1 μm or more, sufficient projections are formed, which is preferable. On the other hand, if the thickness is 15 μm or less, the productivity is good and it is preferable.

The amount of inorganic particles, organic particles, and incompatible resins contained in the curable resin layer and the thickness of the curable resin layer affect the bending resistance of the transparent conductive film. By appropriately selecting the amount of particles, organic particles, and incompatible resin to be added, and the thickness of the functional layer, the bending resistance of the transparent conductive film can be adjusted to the above appropriate value.
Therefore, in the present invention, the effects of the present invention cannot be obtained simply by providing a functional layer, but by having the features of the present invention, it is possible to effectively contribute to the bending resistance of the transparent conductive film. .

In one aspect, the thickness of the cured resin layer and the thickness of the functional layer may be the same. In another aspect, for example, the absolute value of the difference between the thickness of the cured resin layer and the thickness of the functional layer has the following relationship.
0.1 μm≦|Thickness of cured resin layer−Thickness of functional layer|≦3 μm
Thus, in the present invention, the bending resistance of the transparent conductive film can be adjusted to a more preferable range in the present invention by providing a difference between the thickness of the cured resin layer and the thickness of the functional layer. In addition, it is possible to more effectively exhibit various properties such as durability against sliding with a pen, and to obtain a transparent conductive film having light operability.
Moreover, it is preferable that the particle mass per unit volume of the cured resin layer and the particle mass per unit volume of the functional layer are different.

The easy-adhesion layer according to the present invention is preferably formed from a composition containing a urethane resin, a cross-linking agent, and a polyester resin. The cross-linking agent is preferably a blocked isocyanate, more preferably a tri- or more functional blocked isocyanate, and particularly preferably a tetra- or more functional blocked isocyanate. The thickness of the easy-adhesion layer is preferably 0.001 μm or more and 2.00 μm or less.

In one aspect, the present invention provides a resistive touch panel comprising the transparent conductive film of the present invention. The touch panel can have known components in addition to the transparent conductive film of the present invention. With the transparent conductive film for a resistive touch panel of the present invention, the various effects described above can be exhibited more satisfactorily in the touch panel.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Various measurement evaluations in the examples were performed by the following methods.
(1) Total light transmittance Based on JIS-K7361-1:1997, the total light transmittance was measured using NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd.

(2) Surface resistance value Measured by the four-probe method in accordance with JIS-K7194:1994. Lotesta AX MCP-T370 manufactured by Mitsubishi Chemical Analytech Co., Ltd. was used as the measuring instrument.

(3) Evaluation of average maximum peak height The average maximum peak height is the average of five maximum peak heights. As for how to select five points, an arbitrary one point A is first selected. Next, two points in total, one point each 1 cm upstream and downstream of A in the longitudinal (MD) direction of the film, are selected. Next, two points in total, one point on each side of 1 cm in the width (TD) direction of the film with respect to A, are selected. The maximum peak height is specified in ISO 25178, and the three-dimensional surface profile measuring device Vertscan (manufactured by Ryoka Systems Co., Ltd., R5500H-M100 (measurement conditions: wave mode, measurement wavelength 560 nm, objective lens 10 times)) was used to obtain the maximum peak height. Values less than 1 nm were rounded off.

(4) Crystallinity of transparent conductive film A film sample piece laminated with a transparent conductive thin film layer was cut into a size of 1 mm × 10 mm, and was attached to the upper surface of a suitable resin block with the conductive thin film surface facing outward. . After trimming it, an ultrathin section almost parallel to the film surface was made by a common ultramicrotome technique.
This section was observed with a transmission electron microscope (JEM-2010, manufactured by JEOL), and the conductive thin film surface portion without significant damage was selected and photographed at an acceleration voltage of 200 kV and a direct magnification of 40,000.
As the crystallinity evaluation of the transparent conductive film, the ratio of crystal grains observed under a transmission electron microscope, that is, the degree of crystallinity was observed.

(5) Thickness of transparent conductive film (film thickness)
A film sample piece laminated with a transparent conductive thin film layer was cut into a size of 1 mm×10 mm and embedded in an epoxy resin for electron microscopes. This was fixed to a sample holder of an ultramicrotome, and a cross-sectional slice parallel to the short side of the embedded sample piece was produced. Then, a transmission electron microscope (manufactured by JEOL, JEM-2010) is used to photograph a portion of the section where the thin film is not significantly damaged at an acceleration voltage of 200 kV and a bright field with an observation magnification of 10,000 times. The film thickness was obtained from the obtained photograph.

(6) Pen sliding durability test Using a transparent conductive film as one panel plate, as the other panel plate, a 20 nm thick indium-tin composite oxide thin film (tin oxide content : 10% by mass) was used. A touch panel was produced by arranging these two panel plates so that the transparent conductive thin films faced each other with epoxy beads having a diameter of 30 μm interposed therebetween. Next, a linear sliding test of 50,000 reciprocations was performed on the touch panel by applying a load of 2.5 N to a pen made of polyacetal (tip shape: 0.8 mmR). The sliding distance at this time was 30 mm, and the sliding speed was 180 mm/sec. After this sliding durability test, the ON resistance (the resistance value when the movable electrode (film electrode) and the fixed electrode are in contact) was measured when the sliding portion was pressed with a pen load of 0.8N. It is desirable that the ON resistance is 10 kΩ or less.

(7) Measurement of Tin Oxide Content in Transparent Conductive Film Cut a sample (approximately 15 cm ² ) and put it in a quartz Erlenmeyer flask, add 20 ml of 6 mol/l hydrochloric acid, and seal with a film to prevent volatilization of the acid. Did. The transparent conductive film was dissolved by allowing it to stand at room temperature for 9 days with occasional shaking. The remaining film was taken out, and hydrochloric acid in which the transparent conductive film was dissolved was used as a measuring solution. In and Sn in the solution were determined by calibration curve method using an ICP emission spectrometer (manufacturer: Rigaku, device type: CIROS-120 EOP). As the measurement wavelength for each element, a wavelength with no interference and high sensitivity was selected. In addition, standard solutions of commercially available In and Sn were diluted and used.

(8) Input load test method A transparent conductive film (size: 220 mm × 135 mm) is used as one panel plate, and a glass substrate (size: 232 mm × 151 mm) is used as the other panel plate to a thickness of 20 nm by sputtering. A transparent conductive thin film A composed of an indium-tin composite oxide thin film (tin oxide content: 10% by mass) was used.
On the side of the transparent conductive thin film A of the glass substrate with an indium-tin composite oxide thin film, hereinafter also referred to as ITO glass, epoxy resin (length 60 μm × width 60 μm × height 5 μm) was applied as dot spacers in a square grid pattern with a 4 mm pitch. placed in
Next, a double-sided tape (thickness: 105 μm, width 6 mm) was attached to the transparent conductive thin film A side of the ITO glass so that a rectangle of 190 mm × 135 mm was formed starting from one of the four corners of the ITO glass. .
Next, the transparent conductive film B side of the transparent conductive film is pasted on the double-sided tape pasted on the ITO glass, and the transparent conductive thin film A and the transparent conductive film B are laminated so as to face each other.
At this time, one short side of the transparent conductive film protrudes from the ITO glass.
Next, the ITO glass and the transparent conductive film are connected with a tester.
Next, a load is applied from the transparent conductive film side with a polyacetal pen (tip shape: 0.8 mmR), and the load value when the resistance value measured by the tester stabilizes is taken as the input start load.
The position where the load is applied with the pen is the central area surrounded by the four dot spacers, and the average value of the input start load at the three points is calculated.
The position where the load was applied by the pen was the center area of the four dot spacers as shown in FIG. Also, the input start load was measured at arbitrary three points at a distance of 50 mm or more from the double-sided tape, and the average value was taken. Decimals are rounded off.

(9) Film bending resistance test method A test piece of 20 mm x 250 mm is taken from the transparent conductive film, and the test piece is placed on a horizontal table with a smooth surface so that the transparent conductive layer faces upward. . At this time, only the 20 mm×20 mm portion of the test piece is placed on the horizontal table, and the 20 mm×230 mm portion is placed outside the horizontal table. Also, a weight is placed on a 20 mm×20 mm portion of the test piece. At this time, the weight and size of the weight are selected so that there is no gap between the test piece and the horizontal table. Next, read the difference (=.delta.) between the height of the horizontal stage and the height of the leading edge of the film on the scale. Next, the bending resistance is calculated by substituting numerical values into the following equation (1).
Formula (1) (g×a×b×L ⁴ )/8δ (N cm)
g = gravitational acceleration, a = length of the short side of the test piece, b = specific gravity of the test piece, L = length of the test piece, δ = difference between the height of the horizontal stage and the height of the tip of the film

(10) Evaluation of the maximum value of the maximum peak height and the minimum value of the maximum peak height with respect to the average maximum peak height Divide by mountain height.

(11) Adhesion test It was carried out in accordance with JIS K5600-5-6:1999.
The results in the table below show the adhesiveness in terms of residual area ratio. The maximum value of the residual area ratio is 100%. The closer the residual area ratio in the adhesion test in the table is to 100%, the smaller the peeled area.

The transparent plastic film substrate used in Examples and Comparative Examples was a biaxially oriented transparent PET film (A4380 manufactured by Toyobo Co., Ltd., the thickness is shown in Tables 1 and 2) having an easily adhesive layer on both sides. As a curable resin layer, silica particles (manufactured by Nissan Chemical Co., Ltd., Snowtex ZL) are added to 100 parts by mass of an acrylic resin containing a photopolymerization initiator (manufactured by Dainichiseika Kogyo Co., Ltd., Seika Beam (registered trademark) EXF-01J). 1. Blend the amount shown in Table 2, add a mixed solvent of toluene/MEK (8/2: mass ratio) as a solvent so that the solid content concentration becomes the value shown in Table 1 and Table 2, and stir. and uniformly dissolved to prepare a coating liquid (this coating liquid is hereinafter referred to as coating liquid A). The prepared coating solution was applied using a Meyer bar so that the thickness of the coating film would be the value shown in Tables 1 and 2. After drying at 80° C. for 1 minute, the coating film was cured by irradiating ultraviolet rays (light amount: 300 mJ/cm ² ) using an ultraviolet irradiation device (manufactured by Eye Graphics, UB042-5AM-W type). .
Further, under the conditions shown in Tables 1 to 4, a functional layer was formed on the surface of the transparent plastic substrate opposite to the curable resin layer.

(Examples 1 to 7)
Each example level was carried out as follows under the conditions shown in Table 1.
The film was placed in a vacuum chamber and evacuated to 1.5×10 ⁻⁴ Pa. Next, after oxygen was introduced, argon was introduced as an inert gas to make the total pressure 0.6 Pa.
A sintered target of indium-tin composite oxide or a sintered target of indium oxide containing no tin oxide was supplied with power at a power density of 3 W/cm ² to form a transparent conductive film by DC magnetron sputtering. The film thickness was controlled by changing the speed at which the film passed over the target. Also, the ratio of the water pressure to the inert gas in the film formation atmosphere during sputtering was measured using a gas analyzer (Transpector XPR3, manufactured by INFICON). In each example level, as shown in Table 1, in order to adjust the ratio of water pressure to inert gas in the film formation atmosphere during sputtering, the presence or absence of the bombardment process, the uneven height difference of the film roll end face, and the film The temperature of the heating medium of the temperature controller that controls the temperature of the center roll that is running in contact was adjusted. Table 1 shows the center value of the temperature that is right in the middle between the maximum and minimum temperatures from the start of film formation on the film roll to the end of film formation.
The film formed by laminating the transparent conductive film was subjected to the heat treatment shown in Table 1, and then measured. The measurement results are shown in Tables 1, 3 and 4.

(Comparative Examples 1 to 7)
A transparent conductive film was produced and evaluated in the same manner as in Example 1 under the conditions shown in Table 2. The results are shown in Tables 2-4.

As shown in Tables 1 to 4, the transparent conductive films described in Examples 1 to 7 have an input start load within the range of the present invention, so that they have light operability when used in a resistive touch panel. It is excellent in pen sliding durability, and has both characteristics. However, Comparative Examples 1 to 7 cannot achieve both light operability and pen sliding durability.

As described above, according to the present invention, it is possible to provide a transparent conductive film having light operability and excellent pen sliding resistance, which is extremely useful for applications such as resistive touch panels.

1. film 2 . Center roll 3 . Chimney 4. Indium-tin composite oxide target5. Transparent conductive film 6 . Curable resin layer 7 . 7. Transparent plastic film substrate; Functional layer 9 . Easy adhesion layer 10 . ITO glass 11 . Dot spacer 12 . Position to apply load with pen

Claims (8)

A transparent conductive film of indium-tin composite oxide is laminated on at least one side of a biaxially oriented transparent PET film substrate,
A curable resin layer containing an ultraviolet curable resin and one or more particles selected from inorganic particles and organic particles is formed on at least one side of the laminate,
A transparent conductive film, wherein the curable resin layer has a thickness of 0.1 to 15 μm. The transparent conductive film according to claim 1, wherein the curable resin layer is provided between the transparent conductive film and the biaxially oriented transparent PET film substrate. 3. The transparent conductive film according to claim 1, wherein the transparent conductive film has a thickness of 10 nm or more and 100 nm or less. The transparent conductive film according to any one of claims 1 to 3, wherein the concentration of tin oxide contained in the transparent conductive film is 0.5% by mass or more and 40% by mass or less. The transparent conductive film according to any one of claims 1 to 4, further comprising a functional layer on the side of the biaxially oriented transparent PET film base opposite to the transparent conductive film. 6. The transparent conductive film according to any one of claims 1 to 5, having an easily adhesive layer on at least one side of the biaxially oriented transparent PET film substrate. The easy adhesion layer is arranged at least one position between the biaxially oriented transparent PET film substrate and the curable resin layer, or between the biaxially oriented transparent PET film substrate and the functional layer. 7. The transparent conductive film according to claim 6. According to any one of claims 1 to 7, the remaining area ratio of the transparent conductive film is 95% or more in an adhesion test according to JIS K5600-5-6:1999 on the surface of the transparent conductive film. The transparent conductive film described.

Images