TWI873361B - Transparent conductive film - Google Patents

Abstract

[Topic] To provide a transparent conductive film having light operability for use in a touch panel and excellent pen sliding durability. [Solution] A transparent conductive film having a transparent conductive film of an indium-tin composite oxide laminated on at least one side of a transparent plastic film substrate, wherein the input starting load of the transparent conductive film based on a specific input load test method is 3 g or more and 15 g or less.

Description

Transparent conductive film

The present invention relates to a transparent conductive film having a transparent conductive film of an indium-tin composite oxide laminated on a transparent plastic film substrate, and more particularly to a transparent conductive film having light operability and excellent pen sliding durability when used in a resistive film touch panel.

Transparent conductive films, which are thin films with low electrical resistance and are laminated on transparent plastic substrates, are widely used for applications that utilize their electrical conductivity. For example, they are widely used in the electrical and electronic fields as transparent electrodes for flat-panel displays such as liquid crystal displays and electroluminescent (EL) displays, and touch panels.

The resistive film touch panel is a combination of a fixed electrode coated with a transparent conductive film on a glass or plastic substrate and a movable electrode (= thin film electrode) coated with a transparent conductive film on a plastic film, which are superimposed on the upper side of the display. The thin film electrode is pressed with a finger or a pen to make the transparent conductive film of the fixed electrode and the thin film electrode contact each other, which becomes an input for identifying the position of the touch panel. In particular, when inputting with a pen, the pen sliding durability is required. In addition, in recent years, electrostatic capacitive touch panels have gradually become popular, so in terms of resistive film touch panels, as in electrostatic capacitive touch panels, it is also required that input can be performed even with a light touch. For example, there is a strong demand that people who have weak finger pressure or pen pressure due to age, illness, or other reasons can input even with a light touch. However, in the case of a resistive film touch panel, a certain degree of input load is required in order to press the thin film electrode with a finger or a pen so that the fixed electrode and the transparent conductive film of the thin film electrode come into contact with each other, so there is no light operation feeling like an electrostatic capacitance touch panel. In order to solve these problems, a transparent conductive film with light operability is expected. [Prior art literature] [Patent literature]

[Patent Document 1] Japanese Patent Application Publication No. 2004-071171

The conventional transparent conductive film shown in Patent Document 1 attempts to improve the pen sliding durability by controlling the crystallinity of the indium-tin composite oxide. However, the conventional transparent conductive film has insufficient operability when subjected to the input load test described below.

[Problems to be solved by the invention]

The purpose of the present invention is to provide a transparent conductive film with light operability and excellent pen sliding durability in view of the above-mentioned existing problems. [Means for solving the problem]

The present invention was completed in view of the above situation, and the transparent conductive film of the present invention that can solve the above problem is composed of the following structures. 1. A transparent conductive film, wherein a transparent conductive film of indium-tin composite oxide is laminated on at least one side of a transparent plastic film substrate, and the input starting load of the transparent conductive film based on the following input load test is 3g or more and 15g or less. (Input load test method) A transparent conductive film (size: 220 mm × 135 mm) was used as a panel sheet on one side, and a transparent conductive film A including a 20 nm thick indium-tin composite oxide film (tin oxide content: 10 mass %) formed by sputtering on a glass substrate (size: 232 mm × 151 mm) was used as a panel sheet on the other side. On the transparent conductive film A side of the glass substrate with the indium-tin composite oxide film (hereinafter also referred to as ITO glass), epoxy resin (60 μm in length × 60 μm in width × 5 μm in height) was arranged as a dot spacer in a square lattice with a pitch of 4 mm. Next, a double-sided tape (thickness: 105μm, width 6mm) is attached to the transparent conductive film A side of the ITO glass in a 190mm×135mm rectangle, starting from any of the four corners of the ITO glass. Next, the transparent conductive film B side of the transparent conductive film is attached to the double-sided tape attached to the ITO glass, and the transparent conductive film A and the transparent conductive film B are laminated in a face-to-face manner. At this time, one short side of the transparent conductive film is exposed from the ITO glass. Next, the ITO glass and the transparent conductive film are connected with a tester. Next, load is applied gradually from the transparent conductive film side using a polyacetal pen (tip shape: 0.8 mmR), and the load value when the resistance value measured by the test machine stabilizes is set as the input start load. The position where the load is applied with the pen is the central area surrounded by 4 point-shaped spacers, and the average value of the input start load at 3 points is calculated. For example, the input start load is preferably measured at any 3 points more than 50 mm away from the double-sided tape and the average value is taken. In addition, decimal points can be rounded off. In addition, the position where the load is applied with the pen is the central area of 4 point-shaped spacers as shown in FIG6. In FIG6, the symbols 10 represent ITO glass, 11 represent point-shaped spacers, and 12 represent the position where the load is applied with the pen. 2. The transparent conductive film as described above, wherein the soft hardness of the film soft hardness test described below is not less than 0.23N‧cm and not more than 0.90N‧cm, and further, the following average maximum height of the conductive surface of the transparent conductive film satisfies the following formula (2-1) and formula (2-2). (Thin film soft hardness test method) Take a 20mm×250mm test piece from the transparent conductive film, and place the test piece on a horizontal platform with a smooth surface with the transparent conductive layer facing upward. At this time, only the 20mm×20mm part of the test piece is placed on the horizontal platform, and the 20mm×230mm is placed in a manner exposed outside the horizontal platform. In addition, a weight is placed on the 20mm×20mm part of the test piece. At this time, the weight and size of the weight are selected in a manner that no gap is formed between the test piece and the horizontal platform. Next, use a scale to read the difference between the height of the horizontal platform and the height of the front end of the film (hereinafter referred to as δ). Next, substitute the value into the following formula (1) to calculate the hardness. 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 platform and the height of the front end of the film (average maximum height evaluation) The average maximum height is the average of the maximum heights of the 5 points. The 5 points are selected by first selecting any point A. Next, select one point each at 1 cm upstream and downstream of A in the length (MD) direction of the film, for a total of 2 points. Next, select one point each at 1 cm to the left and right of A in the width (TD) direction of the film, for a total of 2 points. The maximum height is defined in ISO 25178 and was determined using a 3D surface profile measuring device, VertScan (R5500H-M100, manufactured by Ryoka System Co., Ltd. (measurement conditions: wave mode, measurement wavelength 560nm, objective 10x)). Values less than 1nm were rounded off for simplification. Formula (2-1) Average maximum mountain height (μm) ≧ 4.7 × soft hardness - 1.8 Formula (2-2) 0.005 (μm) ≦ Average maximum mountain height (μm) ≦ 12.000 (μm) 3. The transparent conductive film as described above, wherein the maximum value of the maximum mountain height in the aforementioned average maximum mountain height evaluation is more than 1.0 times and less than 1.4 times the aforementioned average maximum mountain height, and the minimum value of the maximum mountain height in the aforementioned average maximum mountain height evaluation is more than 0.6 times and less than 1.0 times the aforementioned average maximum mountain height. 4. The transparent conductive film as described above, wherein the thickness of the transparent conductive film is 10 to 100 nm. 5. The transparent conductive film as described above, wherein the concentration of tin oxide contained in the transparent conductive film is 0.5 to 40 mass %. 6. The transparent conductive film as described above, wherein a hardening resin layer is provided between the transparent conductive film and the transparent plastic film substrate, and further a functional layer is provided on the side of the transparent plastic substrate opposite to the transparent conductive film. 7. The transparent conductive film as described above, wherein an easy-adhesion layer is provided on at least one side of the transparent plastic film substrate. 8. The transparent conductive film as described above, wherein the easy-adhesion layer is provided at least at one position between the transparent plastic film substrate and the hardening resin layer, or between the transparent plastic substrate and the functional layer. 9. The transparent conductive film as described above, wherein the ON resistance of the transparent conductive film based on the pen sliding durability test described below is 10 kΩ or less. (Pen sliding durability test) A transparent conductive film is used as a panel sheet on one side, and a transparent conductive film containing a 20nm thick indium-tin composite oxide film (tin oxide content: 10 mass %) formed by sputtering on a glass substrate is used as a panel sheet on the other side. The two panel sheets are arranged face to face with the transparent conductive films, with epoxy beads of 30μm in diameter between them, to produce a touch panel. Then, a load of 2.5N is applied to a polyacetal pen (tip shape: 0.8mmR), and the touch panel is subjected to a straight line sliding test of 50,000 back and forth. The sliding distance at this time is set to 30mm, and the sliding speed is set to 180mm/second. After the sliding durability test, the ON resistance (resistance value when the movable electrode (thin film electrode) and the fixed electrode are in contact) when the sliding part is pressed with a pen load of 0.8N is measured. 10. The transparent conductive film as described above, wherein 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. [Effects of the invention]

According to the present invention, a transparent conductive film having light operability and excellent pen sliding durability can be provided.

[Form used to implement the invention]

The transparent conductive film of the present invention is a transparent conductive film having an indium-tin complex oxide layered on at least one side of a transparent plastic film substrate, and the input starting load of the transparent conductive film based on the following input load test is 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 a panel sheet on one side, and a transparent conductive film A including an indium-tin complex oxide thin film (tin oxide content: 10 mass %) with a thickness of 20 nm formed by sputtering on a glass substrate (size: 232 mm × 151 mm) is used as a panel sheet on the other side. On the transparent conductive film A side of a glass substrate with an indium-tin composite oxide thin film (hereinafter also referred to as ITO glass), epoxy resin (60μm in length × 60μm in width × 5μm in height) as dot spacers was arranged in a square grid with a pitch of 4mm. Then, starting from any of the four corners of the ITO glass, a double-sided tape (thickness: 105μm, width 6mm) was attached to the transparent conductive film A side of the ITO glass in a manner that formed a rectangle of 190mm × 135mm. Then, the transparent conductive film B side of the transparent conductive film was attached to the double-sided tape attached to the ITO glass, and the transparent conductive film A and the transparent conductive film B were laminated in a manner that the transparent conductive film A and the transparent conductive film B faced each other. At this time, one short side of the transparent conductive film is exposed from the ITO glass. Then, the ITO glass and the transparent conductive film are connected with a tester. Then, 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 is stable is set as the input start load. The position where the load is applied with the pen is the center area surrounded by 4 dot-shaped spacers, and the average value of the input start load at 3 points is calculated. For example, the input start load is preferably measured at any 3 points more than 50 mm away from the double-sided tape and the average value is taken. In addition, decimal points can be rounded off. In addition, the position where the load is applied with the pen is the center area of 4 dot-shaped spacers as shown in Figure 6.

Here, in the present invention, when measuring with a tester, the "stable resistance value" is preferably judged as a state in which the resistance value varies within a range of, for example, ±5% depending on external factors such as the environment in which the measurement is performed.

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 in applications such as resistive film touch panels.

The transparent conductive film of the present invention has easy handling. The transparent conductive film of indium-tin composite oxide with excellent handling is found to have the following conditions: the maximum height of the side surface of the transparent conductive film is within a suitable range relative to the height of the dot-shaped spacers located on the ITO glass for touch panels; the film has a low hardness based on a hardness test; and the tin oxide concentration of the transparent conductive film is close to the tin oxide concentration of the ITO glass for touch panels.

The light operability is explained. The so-called light operability means that even if the resistive film touch panel is pressed lightly with a pen or a finger from the transparent conductive film side, input can be performed on the resistive film touch panel. In the present invention, the light operability is evaluated by an input load test. In the present invention, if the input start load of the transparent conductive film based on the input load test is 3g or more and 15g or less, it has light operability. The present invention having such an input start load is a transparent conductive film used for resistive film touch panels, etc., and even for people who have weak finger pressing force or pen pressure due to age, illness, or other reasons, input can be performed by light touch. If the input start load is 15g or less, it is preferred to have light operability. It is more preferred to be 13g or less. It is still more preferred to be 11g or less. On the other hand, if the input start load is 3g or more, it is preferred to prevent erroneous response of the touch panel. It is more preferred to be 5g or more, and still more preferred to be 8g or more.

In the present invention, the hardness of the film hardness test is preferably 0.23N‧cm or more and 0.90N‧cm or less, and the average maximum height of the transparent conductive film side of the transparent conductive film satisfies the following formula (2-1) and formula (2-2). First, the hardness based on the film hardness test is explained. In the film hardness test, the test piece is placed on a flat surface with a transparent conductive layer facing up. This is because: from the non-transparent conductive layer side, the transparent conductive film is pressed with a pen or finger to make the direction of deformation of the transparent conductive film consistent. Even for the same transparent conductive film, the hardness value in the film hardness test will change depending on whether the transparent conductive layer is facing up or down, so it is necessary to pay attention when evaluating. In addition, when the curing resin layer is arranged between the transparent plastic substrate and the transparent conductive film, the thickness and hardness of the curing resin layer will also affect the softness and hardness. In addition, when the curing resin layer is arranged on both sides of the transparent plastic substrate, the balance of the thickness and hardness of the curing resin layer on each side will affect the softness and hardness.

If the soft hardness of the transparent conductive film is 0.23N‧cm or more, it is difficult for the transparent conductive film to deform when it is accidentally touched with very light force, so it is difficult to cause electrical contact between the transparent conductive film of the transparent conductive film and the transparent conductive film of the ITO glass for the touch panel, which is easy to prevent erroneous input. In addition, the pen sliding durability is also excellent, so it is better. More preferably, it is 0.27N‧cm or more. More preferably, it is 0.30N‧cm or more. On the other hand, if the soft hardness of the transparent conductive film is 0.90N‧cm or less, the transparent conductive film becomes easily deformed even when pressed with a pen or finger with a low input load from the transparent conductive film side, so that the transparent conductive film of the transparent conductive film and the transparent conductive film of the ITO glass become easily electrically contacted, so it is better to have light operability. More preferably, it is 0.80N‧cm or less. More preferably, it is 0.70N‧cm or less. Particularly preferably, it is 0.60N‧cm or less.

(Thin film hardness test method) Take a 20mm×250mm test piece from a transparent conductive film, and place the test piece on a smooth horizontal platform with the transparent conductive layer facing upward. At this time, only the 20mm×20mm part of the test piece is placed on the horizontal platform, and the 20mm×230mm is placed in a manner that is exposed outside the horizontal platform. In addition, place a weight on the 20mm×20mm part of the test piece. At this time, select the weight and size of the weight so that there is no gap between the test piece and the horizontal platform. Then, use a ruler to read the difference (=δ) between the height of the horizontal platform and the height of the front end of the film. Then, substitute the value into the following formula (1) to calculate the hardness. 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 platform and the height of the front end of the film

In the present invention, it is preferred that when performing a film hardness test, the hardness of the film hardness test is 0.23N‧cm or more and 0.90N‧cm or less, and the average maximum height below the transparent conductive film side of the transparent conductive film satisfies the following formula (2-1) and formula (2-2). (Average maximum height evaluation) The average maximum height is the average of the maximum heights of 5 points. The 5 points are selected by first selecting any point A. Then, select one point each at 1 cm upstream and downstream relative to A in the length (MD) direction of the film, for a total of 2 points. Then, select one point each at 1 cm to the left and right of A in the width (TD) direction of the film, for a total of 2 points. The maximum height is specified in ISO 25178 and is obtained using the 3D surface shape measuring device VertScan (R5500H-M100 manufactured by Ryoka System Co., Ltd. (measurement conditions: wave mode, measurement wavelength 560nm, objective 10x)). In addition, values less than 1nm are rounded off for simplification. Formula (2-1)    Average maximum height (μm) ≧ 4.7 × hardness - 1.8 Formula (2-2)    0.005 (μm) ≦ Average maximum height (μm) ≦ 12.000 (μm)

If the maximum height of the surface on the transparent conductive film side satisfies formula (2-1) and formula (2-2), the transparent conductive film disposed on the projection on the transparent conductive film side of the transparent conductive film and the transparent conductive film of the ITO glass for the touch panel can be electrically contacted even when the transparent conductive film side is pressed with a pen or a finger with a low input load, so it is preferably easy to operate. It is more preferable that the y intercept of formula (2-1), that is, the value represented by "-1.8" in the above formula (2-1) is greater than -1.7. It is even more preferable that the y intercept of formula (2-1) is greater than -1.6. In addition, if the average maximum height is greater than 0.005 (μm), the transparent conductive film can be rolled into a roll without hindrance, which is more preferable. It is more preferably 0.010 (μm) or more. It is even more preferably 0.020 (μm) or more. In addition, if the average maximum height is 12.000 (μm) or less, it is difficult for the transparent conductive film disposed on the transparent conductive film side of the transparent conductive film and the transparent conductive film of the ITO glass for the touch panel to have accidental electrical contact, so it is easy to prevent erroneous input. It is more preferably 11.000 (μm) or less. It is even more preferably 10.000 (μm) or less. From the above content, it is found that the light operability, etc. are satisfied by the appropriate balance between softness and hardness and the average maximum height.

In the present invention, the maximum value of the maximum height in the average maximum height evaluation described below is more than 1.0 times and less than 1.4 times the above average maximum height, and The minimum value of the maximum height in the average maximum height evaluation is more than 0.6 times and less than 1.0 times the above average maximum height. If it is within the above range, the deviation of the input start load becomes less than ±5%, which is preferred. If the minimum value of the maximum height in the average maximum height evaluation is more than 0.6 times the average maximum height, the high protrusions on the transparent conductive film side of the transparent conductive film related to light operability are uniformly distributed in the surface, so when pressing with a pen or a finger from the transparent conductive film side, the touch panel can be input with the same input load regardless of the position, which is preferred. More preferably, it is more than 0.7 times. More preferably, it is more than 0.8 times. On the other hand, if the maximum value of the maximum peak height in the average maximum peak height evaluation is less than 1.4 times the average maximum peak height, the high protrusions on the transparent conductive film side of the transparent conductive film related to light operability are evenly distributed in the surface, so when pressing with a pen or a finger from the transparent conductive film side, the touch panel can be input with the same input load regardless of the position, which is better. More preferably, it is less than 1.3 times. More preferably, it is less than 1.2 times.

(Average maximum height evaluation) The average maximum height is the average of the maximum heights of the five points. The five points are selected by first selecting any point A. Then, one point is selected 1 cm upstream and downstream of A in the length (MD) direction of the film, for a total of two points. Then, one point is selected 1 cm to the left and right of A in the width (TD) direction of the film, for a total of two points. The maximum height is specified in ISO 25178, and the maximum height is obtained using the 3D surface shape measuring device VertScan (R5500H-M100 manufactured by Ryoka System Co., Ltd. (measurement conditions: wave mode, measurement wavelength 560nm, objective 10x)). In addition, values less than 1nm are rounded off for simplification.

The transparent conductive film of the present invention comprises an indium-tin composite oxide. The surface resistance of the transparent conductive film of the present invention is preferably 50 to 900 Ω/□, more preferably 50 to 700 Ω/□. In addition, the total light transmittance of the transparent conductive film of the present invention is preferably 70 to 95%.

In the present invention, the thickness of the transparent conductive film is preferably not less than 10nm and not more than 100nm. If the thickness of the transparent conductive film is not less than 10nm, the transparent conductive film is entirely attached to the transparent film substrate or the hardened resin layer, and the film quality of the transparent conductive film is stable, so as a result, the surface resistance value is stably within a preferred range, which is preferred. It is more preferred that the thickness of the transparent conductive film is not less than 13nm, and more preferably not less than 16nm. In addition, if the thickness of the transparent conductive film is not more than 100nm, the crystal grain size and degree of crystallization of the transparent conductive film are appropriate, and further the total light transmittance reaches a practical level, which is preferred. It is more preferred to be not more than 50nm, more preferably not more than 30nm, and particularly preferably not more than 25nm.

In the present invention, the concentration of tin oxide contained in the transparent conductive film of the transparent conductive film is preferably 0.5 to 40% by mass. It is found that if the concentration of tin oxide contained in the transparent conductive film of the transparent conductive film is closer to the concentration of tin oxide contained in the ITO glass for touch panels, the transparent conductive film of the transparent conductive film and the transparent conductive film of the ITO glass are more easily in electrical contact, thus having light operability. Generally speaking, the concentration of tin oxide contained in the ITO glass for touch panels is 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 the touch panel is 30 mass % or less, the transparent conductive film of the transparent conductive film and the transparent conductive film of the ITO glass become easily in electrical contact, thus having light operability and being preferred.

The concentration of tin oxide contained in ITO glass for touch panels is mostly 10 mass%. Therefore, in the present invention, the tin oxide concentration of the transparent conductive film is preferably 40 mass% or less. More preferably, it is 25 mass% or less. More preferably, it is 20 mass% or less. Particularly preferably, it is 2 mass% or more and 18 mass% or less. In addition, if it contains 0.5 mass% or more of tin oxide, the surface resistance of the transparent conductive film reaches a practical level and is better. More preferably, the content of tin oxide is 1 mass% or more, and particularly preferably, it is 2 mass% or more.

In one embodiment, the transparent conductive film of the present invention has a hardened resin layer between the transparent conductive film and the transparent plastic film substrate.

It is preferred that a functional layer is further provided on the side of the transparent plastic substrate opposite to the transparent conductive film.

As shown in FIG2 , the structure example can sequentially include a transparent conductive film 5, a hardening resin layer 6, a transparent plastic film substrate 7, and a functional layer 8.

During the touch panel processing step, the transparent conductive film is heated. At this time, if monomers and oligomers generated from the transparent plastic film substrate are precipitated onto the transparent conductive film, there is a risk of hindering the smooth operability of the touch panel.

Therefore, it is better to have a hardened resin layer between the transparent conductive film and the transparent plastic film substrate to prevent monomers and oligomers from precipitating onto the transparent conductive film.

In addition, since there is a concern that monomers and oligomers precipitated from the transparent plastic substrate may reduce the visibility of the transparent conductive film, it is preferable to have a hardened resin layer and a functional layer on the transparent plastic film substrate. In addition, by having a hardened resin layer and a functional layer, the hardness of the transparent conductive film can be adjusted within a more optimal range in the present invention. The hardened resin layer and the functional layer of the present invention can more effectively exhibit various characteristics such as pen sliding durability. In particular, in the present invention, by having a hardened resin layer and a functional layer, the hardness of the transparent conductive film of the present invention can be adjusted, the input starting load can be adjusted within a predetermined range, and excellent visibility can be produced. Although it should not be construed as being limited to a specific theory, in the present invention, by having both a hardened resin layer and a functional layer, it is possible to display light operability and more accurate input in a resistive film touch panel. In addition, by having a hardened resin layer on the transparent plastic film substrate, in addition to increasing the adhesion of the transparent conductive film, the force applied to the transparent conductive film can be dispersed, so that cracking, peeling, and abrasion of the transparent conductive film under the pen sliding durability test can be suppressed, which is preferable. In addition, by having a functional layer on the transparent plastic film substrate, it becomes difficult to scratch due to input with a pen, etc., which is preferable.

In one embodiment, the transparent conductive film of the present invention is a transparent plastic film substrate on which an easy-to-adhesive layer is laminated. For example, the transparent conductive film of the present invention preferably includes an easy-to-adhesive layer between the transparent plastic film substrate and the curable resin layer, between the transparent plastic film substrate and the functional layer, or both. The configuration examples are shown in FIG3, FIG4, and FIG5. In these figures, an easy-to-adhesive layer 9 is configured. Other symbols are synonymous with FIG2. By having an easy-to-adhesive layer, the curable resin layer and the functional layer can be firmly adhered to the transparent plastic film substrate, so that the peeling of the curable resin layer and the functional layer caused by external force can be more effectively suppressed.

The transparent conductive film of the present invention is a transparent conductive film having an indium-tin composite oxide layered on at least one surface of a transparent plastic film substrate, and the transparent conductive film has an ON resistance of 10 kΩ or less based on the following pen sliding durability test. (Pen sliding durability test) The transparent conductive film of the present invention is used as a panel sheet on one side, and a transparent conductive film including an indium-tin composite oxide thin film (tin oxide content: 10 mass %) with a thickness of 20 nm formed by sputtering on a glass substrate is used as a panel sheet on the other side. The two panels are placed face to face with transparent conductive films, separated by epoxy beads of 30μm in diameter, and the panel sheets on the film side and the panel sheets on the glass side are attached with double-sided tape of 170μm thickness to make a touch panel. Then, a load of 2.5N is applied to a polyacetal pen (tip shape: 0.8mmR), and the touch panel is subjected to a straight line sliding test 50,000 times back and forth. In this test, the load of the pen is applied to the transparent conductive film surface of the present invention. The sliding distance at this time is set to 30mm, and the sliding speed is set to 180mm/second. After this sliding durability test, the ON resistance (resistance value when the movable electrode (thin film electrode) and the fixed electrode are in contact) is measured when the sliding part is 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 based on the pen sliding durability test is 10kΩ or less, then even if the touch panel is continuously input with a pen, the transparent conductive film can still be suppressed from cracking, peeling, and abrasion, which is preferred. In one embodiment, the ON resistance can be 9.5kΩ or less, and preferably 5kΩ or less. For example, the ON resistance is 3kΩ or less, and can be 1.5kΩ or less, and preferably 1kΩ or less.

The ON resistance is, for example, 5kΩ or more, 3kΩ or more, and preferably 0kΩ or more.

By keeping the ON resistance within this range, the transparent conductive film can be prevented from cracking, peeling, and wearing even if the touch panel is continuously input with a pen.

In one embodiment, these upper and lower limits can be combined as appropriate.

For example, the transparent conductive film of the present invention has 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. The transparent conductive film of the present invention preferably has a residual area ratio of 95% or more even when the adhesion test (JIS K5600-5-6:1999) is performed on the surface of the transparent conductive film, more preferably has a residual area ratio of 99% or more, and particularly preferably has a residual area ratio of 99.5% or more. By making the residual area ratio of the transparent conductive film in the adhesion test within the above range, the transparent conductive film is closely attached to the transparent plastic film substrate, the hardened resin layer, etc., which are in contact with the transparent conductive film. Therefore, even if the touch panel is continuously input with a pen, the transparent conductive film can be suppressed from cracking, peeling, and abrasion. In addition, even if a force greater than that assumed in normal use is applied, the transparent conductive film can still be suppressed from cracking, peeling, etc., which is preferable.

For example, in the transparent conductive film of the present invention, the residual area rate of the functional layer on the surface of the functional layer in the adhesion test according to JIS K5600-5-6:1999 is 95% or more. The transparent conductive film of the present invention preferably has a residual area rate of 95% or more on the functional layer even when the adhesion test (JIS K5600-5-6:1999) is performed on the functional layer, more preferably has a residual area rate of 99% or more on the functional layer, and particularly preferably has a residual area rate of 99.5% or more. The transparent conductive film whose functional layer does not peel off in the adhesion test is a transparent plastic film substrate and a functional layer that are closely attached. Therefore, even if the touch panel is continuously input with a pen, the appearance defects such as cracking, peeling, and abrasion of the functional layer can be suppressed. In addition, even if a force greater than that assumed in normal use is applied, the functional layer mitigates the strong force, so the transparent conductive film can still be suppressed from cracking, peeling, etc., which is better.

The manufacturing method for obtaining the transparent conductive film of the present invention is not particularly limited, and for example, the following manufacturing method can be preferably exemplified. As a method for forming a transparent conductive film of indium-tin complex oxide on at least one side of a transparent plastic film substrate, a sputtering method can be preferably used. In order to manufacture a transparent conductive film with high productivity, it is preferably to use the following roller sputtering device: supplying a film roll, and after film formation, rolling it into the shape of a film roll. It can be preferably adopted: using a mass flow controller in the film-forming gas environment, flowing inert gas and oxygen, using a sintered target of indium-tin complex oxide, adjusting the thickness of the transparent conductive film of indium-tin complex oxide to 10 to 100 nm, and forming a transparent conductive film on a transparent plastic film. In order to improve production efficiency, multiple indium-tin composite oxide sintering targets can be set in the flow direction of the film. In addition, a mass flow controller can be used in the film-forming gas environment to flow a gas containing hydrogen atoms (if it is a gas containing hydrogen atoms such as hydrogen, ammonia, hydrogen + argon mixed gas, there is no special limitation. However, water is excluded.). It is known that if there is too much water in the film-forming gas environment, the film quality of the transparent conductive film will be reduced, the surface resistance value will exceed the optimal range, and the originally crystallized transparent conductive film will not be crystallized, etc., which will have an adverse effect on the film quality of the transparent conductive film. Therefore, the amount of water in the film-forming gas environment is also an important factor. By controlling the central value (the middle value between the maximum and minimum values) of the partial pressure ratio of water to inert gas in the film-forming gas environment during sputter coating of the film roll to 7.00×10 ^-3 or less, it is possible to suppress the degradation of the film quality of the transparent conductive film, which is preferred. In order to control the amount of water in the film-forming gas environment, in addition to the rotary pump, turbomolecular pump, and cryopump that are often used as exhaust devices for sputter coating machines, there are also the bombardment step described below, the limitation of the height difference of the concave and convex end surface of the film roll described below, and the attachment of a protective film with low water absorption to the opposite side of the surface on which the transparent conductive film is formed. It is preferred that the amount of water released from the film when the transparent conductive film is formed is reduced. In addition, it is preferred to make the film temperature during sputtering below 0°C to form a transparent conductive film on a transparent plastic film. The film temperature during film formation is replaced by the set temperature of a temperature controller that adjusts the temperature of the center roller that contacts the traveling film. Here, FIG1 shows a schematic diagram of an example of a sputtering device suitable for use in the present invention, in which the traveling film 1 travels in partial contact with the surface of the center roller 2. An indium-tin sputtering target 4 is set through a mask (chimney) 3, and a thin film of indium-tin composite oxide is deposited on the surface of the film 1 traveling on the center roller 2. The center roller 2 is temperature-controlled by a temperature controller not shown. If the film temperature is below 0°C, the release of impurities such as water and organic gas from the film that degrade the film quality of the transparent conductive film can be suppressed, which is preferred. In addition, in order to make the surface resistance and total light transmittance of the transparent conductive film reach practical levels, it is ideal to add oxygen during sputtering.

In terms of controlling the amount of water when forming an indium-tin composite oxide film on a plastic film, it is more ideal to observe the amount of water during actual film formation rather than the degree of vacuum achieved, for the following two reasons.

The first reason is that when sputtering is used to form a film on a plastic film, the film is heated and water is released from the film. Therefore, the amount of water in the film-forming gas environment increases, and the increase is greater than the amount of water measured when the vacuum degree is reached. Therefore, it is more accurate to express it in terms of the amount of water when the film is formed rather than in terms of the vacuum degree reached.

The second reason is the case of a device that throws in a large amount of transparent plastic film. Such a device throws in the film in the form of a film roll. If the film is rolled up and thrown into a vacuum tank, the water will easily escape from the outer layer of the roll, but it will be difficult for the water to escape from the inner layer of the roll. This is because: when the vacuum degree is measured, the film roll is stopped, and when the film is formed, the film roll is moving, so the inner layer of the film roll containing a lot of water is rolled out one after another, so the moisture content in the film-forming gas environment increases, and the increase is greater than the moisture content when the vacuum degree is measured. In the present invention, when it is desired to control the amount of water in the film-forming gas environment, the partial pressure ratio of water to inert gas in the film-forming gas environment during sputtering is observed, thereby enabling a better response.

It is ideal to subject the film to a bombardment step before forming the transparent conductive film. The bombardment step refers to the process of applying a voltage to discharge the film while only an inert gas such as argon is flowing in, or a mixed gas of a reactive gas such as oxygen and an inert gas is flowing in, so that plasma is generated. Specifically, it is ideal to bombard the film by RF sputtering using a SUS target or the like. The film is exposed to plasma by the bombardment step, so that water and organic components are released from the film. When the transparent conductive film is formed, the amount of water and organic components released from the film is reduced, so that the film quality of the transparent conductive film is improved, which is better. In addition, the layer that the transparent conductive film contacts is activated by the bombardment step, so that the adhesion of the transparent conductive film is improved, and thus the pen sliding durability is improved, which is more ideal.

The height difference between the most convex part and the most concave part of the film roll for forming the transparent conductive film is preferably 10 mm or less at the end surface of the film roll. If it is 10 mm or less, when the film roll is put into the sputtering device, water and organic components from the end surface of the film become difficult to release, so the film quality of the transparent conductive film is improved, which is preferred.

In the film (transparent plastic film substrate) forming the transparent conductive film, it is desirable to attach a protective film with low water absorption to the opposite side of the surface forming the transparent conductive film. By attaching the protective film with low water absorption, it becomes difficult to release gas such as water from the film substrate, and the film quality of the transparent conductive film is improved, which is preferable. As the substrate of the protective film with low water absorption, polyethylene, polypropylene, cycloolefin, etc. are preferable.

In a method in which a transparent conductive film of a crystalline indium-tin composite oxide is formed on at least one side of a transparent plastic film substrate, it is desirable to introduce oxygen during sputtering. If oxygen is introduced during sputtering, there will be no defects caused by lack of oxygen in the transparent conductive film of the indium-tin composite oxide, and the surface resistance of the transparent conductive film will be lower and the total light transmittance will be higher, which is preferred. Therefore, in order to make the surface resistance and total light transmittance of the transparent conductive film reach a practical level, it is desirable to introduce oxygen during sputtering. In addition, the total light transmittance of the transparent conductive film of the present invention is preferably 70 to 95%.

The transparent conductive film of the present invention is preferably formed by forming and laminating a transparent conductive film of an indium-tin composite oxide on a transparent plastic film substrate, and then applying a heat treatment at 80 to 200°C for 0.1 to 12 hours in a gas environment containing oxygen. If it is 80°C or higher, it is preferable when the crystallinity of the transparent conductive film must be improved for the purpose of improving the sliding durability of the pen. If it is 200°C or lower, it is preferable because the planarity of the transparent plastic film can be ensured.

<Transparent plastic film substrate> The transparent plastic film substrate used in the present invention refers to a film obtained by melt extrusion or solution extrusion of an organic polymer, and stretched, cooled, or heat-fixed in the length direction and/or width direction as required. Examples of the organic polymer include polyethylene, polypropylene, polyethylene terephthalate, polyethylene 2,6-naphthalate, polytrimethylene terephthalate, polybutylene terephthalate, nylon 6, nylon 4, nylon 66, nylon 12, polyimide, polyamide imide, polyether sulfide, polyether ether ketone, polycarbonate, polyarylate, cellulose propionate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyether imide, polyphenylene sulfide, polyphenylene ether, polystyrene, para-polystyrene, and norbornene polymers.

Among these organic polymers, suitable ones are polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate, para-polystyrene, norbornene polymers, polycarbonate, polyarylate, etc. In addition, these organic polymers can also be copolymerized with a small amount of monomers of other organic polymers or 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, fluorescence discharge treatment, flame treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, ozone treatment, etc. within the scope that does not impair the purpose of the present invention.

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

If a hardening resin layer is laminated on a transparent plastic film substrate, it is possible to prevent monomers and oligomers generated from the transparent plastic film substrate from precipitating onto the transparent conductive film, so that the smooth operability of the touch panel is not hindered, which is preferred. In addition, since the transparent conductive film can be strongly adhered to the hardening resin layer and the force applied to the transparent conductive film can be dispersed, it is possible to suppress cracking, peeling, and abrasion of the transparent conductive film under a pen sliding durability test, which is preferred. In order to improve the adhesion between the transparent plastic film substrate and the hardening resin layer, it is preferred to set an easy-adhesion layer between the transparent plastic film substrate and the hardening resin layer.

If the functional layer is laminated on the transparent plastic film substrate, the monomers and oligomers generated from the transparent plastic film substrate can be blocked from precipitating, thereby suppressing the visibility of the transparent conductive film from decreasing, which is preferred. In order to adjust the softness and hardness of the transparent conductive film, it is preferred to have the functional layer on the transparent plastic film substrate. In addition, by having the functional layer on the transparent plastic film substrate, it is difficult to scratch it due to input with a pen, etc., which is preferred.

In addition, the resin contained in the aforementioned hardening resin layer and the functional layer that can be preferably used in the present invention is not particularly limited if it is a resin that is hardened by energy application such as heating, ultraviolet irradiation, electron beam irradiation, etc., and can be cited as: silicone resin, acrylic resin, methacrylic resin, epoxy resin, melamine resin, polyester resin, urethane resin, etc. From the perspective of productivity, it is preferred to use ultraviolet curing resin as the main component. The resin contained in the hardening resin layer and the functional layer may be the same resin or different resins.

Examples of such UV-curable resins include polyfunctional acrylate resins such as acrylic acid or methacrylic acid esters of polyols, and polyfunctional urethane acrylate resins synthesized from diisocyanate, polyols, and hydroxyalkyl esters of acrylic acid or methacrylic acid. If necessary, monofunctional monomers such as vinyl pyrrolidone, methyl methacrylate, and styrene may be added to these polyfunctional resins to allow copolymerization.

Furthermore, in order to improve the adhesion between the transparent conductive film and the curing resin layer, it is effective to treat the surface of the curing resin layer by the following methods. Specific methods include: discharge treatment by irradiation with light or corona discharge to increase carbonyl, carboxyl, and hydroxyl groups; chemical treatment by treatment with acid or alkali to increase polar groups such as amine, hydroxyl, and carbonyl groups.

UV-curable resins are usually used by adding a photopolymerization initiator. As the photopolymerization initiator, a known compound that absorbs ultraviolet light to generate free radicals can be used without particular limitation. Examples of such photopolymerization initiators include various benzoins, phenyl ketones, and benzophenones. The amount of the photopolymerization initiator added is preferably 1 to 5 parts by mass per 100 parts by mass of the UV-curable resin.

In addition, in the present invention, the hardening resin layer and the functional layer preferably use inorganic particles and organic particles in addition to the hardening resin as the main component. By dispersing the inorganic particles and the organic particles in the hardening resin, the surface of the hardening resin layer and the functional layer can be formed with unevenness, and the surface roughness of a wide area can be improved. In the present invention, by improving the surface roughness of the hardening resin layer, the hardness of the transparent conductive film can be adjusted within a better range in the present invention. In addition, various characteristics such as pen sliding durability, anti-Newton ring, and film rollability can be more effectively demonstrated. In the present invention, by increasing the surface roughness of the functional layer, the hardness and softness of the transparent conductive film can be adjusted within a more optimal range in the present invention. In addition, various characteristics such as the film's rollability, the writing feel of a pen, etc., and the touch of fingers can be more effectively demonstrated.

Examples of the inorganic particles include silicon oxide, etc. Examples of the inorganic particles include polyester resins, polyolefin resins, polystyrene resins, polyamide resins, etc. The particles contained in the curing 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 preferred to use a resin that is incompatible with the hardening resin in addition to the hardening resin as the main component. By using a small amount of a resin that is incompatible with the hardening resin of the matrix, phase separation can be caused in the hardening resin, and the incompatible resin can be dispersed into particles. The dispersed particles of the incompatible resin can form irregularities on the surface of the hardening resin layer and the functional layer, thereby improving the surface roughness of a wide area.

Examples of the incompatible resin include polyester resins, polyolefin resins, polystyrene resins, and polyamide resins.

Here, as an example, the blending ratio of the case where inorganic particles are used in the curing resin layer is shown. For every 100 parts by mass of the UV curing resin, the inorganic particles are preferably in the range of 0.1 to 30 parts by mass, more preferably in the range of 0.1 to 25 parts by mass, and particularly preferably in the range of 0.1 to 20 parts by mass. If the blending amount of the aforementioned inorganic particles is in the range of 0.1 to 30 parts by mass per 100 parts by mass of the UV curing resin, the convex portions formed on the surface of the curing resin layer will not be too small, and an effective average maximum height can be given, which provides light operability for the touch panel. In addition, since there are slight surface protrusions on the transparent conductive film, the film rollability can be maintained, which is preferred. In addition, when inorganic particles are used in the hardening resin layer, the higher the blending ratio is within the above range, the higher the average maximum peak height of the hardening resin layer tends to be. In addition, when inorganic particles are used in the hardening resin layer, the higher the blending ratio is within the above range, the higher the softness and hardness of the transparent conductive film tends to be increased.

Here, as an example, the blending ratio of inorganic particles in the functional layer is shown. For every 100 parts by mass of the UV-curable resin, the inorganic particles are preferably 0.1 parts by mass or more and 60 parts by mass or less. When the inorganic particles are used in the functional layer, the higher the blending ratio within the above range, the lower the softness and hardness of the transparent conductive film tends to be. If the blending amount of the aforementioned inorganic particles is 0.1 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the UV-curable resin, the softness and hardness of the transparent conductive film can be adjusted to the appropriate value of the present invention, which is preferred. In addition, since the surface protrusions are formed on the functional layer within the range that does not impair the effect of the present invention, the film rollability can be maintained, which is preferable.

The aforementioned UV-curable resin, photopolymerization initiator, and resin incompatible with inorganic particles, organic particles, and UV-curable resin are dissolved in a common solvent to prepare a coating solution. There is no particular limitation on the solvent used, for example, alcohol solvents such as ethanol and isopropyl alcohol; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as dibutyl ether and ethylene glycol monoethyl ether; ketone solvents such as methyl isobutyl ketone and cyclohexanone; aromatic hydrocarbon solvents such as toluene, xylene, and solvent naphtha can be used alone or in combination.

The concentration of the resin component in the coating liquid (i.e., the solid component concentration) can be appropriately selected in consideration of the viscosity corresponding to the coating method. For example, 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 tends to be. In addition, other known additives, such as silicone-based leveling agents, can also be added to the coating liquid as needed.

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

The coating liquid is a solvent that is evaporated and removed in the subsequent drying step. In this step, the high molecular weight polyester resin uniformly dissolved in the coating liquid becomes particles and precipitates in the UV curing resin. After the coating is dried, the UV curing resin is crosslinked and cured by irradiating the plastic film with ultraviolet rays to form a curing resin layer and a functional layer. In this curing step, the particles of the high molecular weight polyester resin are fixed in the hard coating layer, and protrusions are formed on the surface of the curing resin layer and the functional layer, thereby increasing the surface roughness of a wide area.

In addition, the thickness of the hardening resin layer is preferably within the range of 0.1 μm to 15 μm. It is more preferably within the range of 0.5 μm to 10 μm, and particularly preferably within the range of 1 μm to 8 μm. When the thickness of the hardening resin layer is 0.1 μm or more, sufficient protrusions can be formed, which is preferred. On the other hand, if it is 15 μm or less, productivity is better. In addition, if the hardening resin layer is thick, the softness and hardness of the transparent conductive film tend to increase.

In addition, the thickness of the functional layer is preferably within the range of 0.1 μm to 15 μm. It is more preferably within the range of 0.5 μm to 15 μm, and particularly preferably within the range of 1 μm to 10 μm. If the functional layer is thick, the softness and hardness of the transparent conductive film tend to be reduced. When the thickness of the functional layer is 0.1 μm or more, sufficient protrusions can be formed, which is preferred. On the other hand, if it is 15 μm or less, productivity is better.

The amount of inorganic particles, organic particles, and incompatible resins added to the curing resin layer and the thickness of the curing resin layer affect the hardness and softness of the transparent conductive film. By appropriately selecting the amount of inorganic particles, organic particles, and incompatible resins added to the functional layer and the thickness of the functional layer, the hardness and softness of the transparent conductive film can be made the above-mentioned appropriate value. Therefore, in the present invention, if only the functional layer is provided, the effect of the present invention cannot be obtained. By having the characteristics of the present invention, the hardness and softness of the transparent conductive film can be effectively contributed.

In one embodiment, the thickness of the hardened resin layer and the thickness of the functional layer may be the same. In another embodiment, the absolute value of the difference between the thickness of the hardened resin layer and the thickness of the functional layer has the following relationship. 0.1μm≦∣Thickness of hardened resin layer-Thickness of functional layer∣≦3μm In this way, in the present invention, by setting a difference between the thickness of the hardened resin layer and the thickness of the functional layer, the softness and hardness of the transparent conductive film can be adjusted within a better range in the present invention. In addition, a transparent conductive film that can more effectively exhibit various characteristics such as pen sliding durability and has light operability can be obtained. Furthermore, it is preferred that the particle mass per unit volume of the hardened resin layer and the particle mass per unit volume of the functional layer are different.

The easy-bonding layer of the present invention is preferably formed of a composition containing a urethane resin, a crosslinking agent, and a polyester resin. The crosslinking agent is preferably a blocked isocyanate, more preferably a trifunctional or higher blocked isocyanate, and particularly preferably a tetrafunctional or higher blocked isocyanate. The thickness of the easy-bonding layer is preferably 0.001 μm or more and 2.00 μm or less.

In one embodiment, the present invention provides a resistive film touch panel having the transparent conductive film of the present invention. The touch panel can have known parts in addition to the transparent conductive film of the present invention. If the resistive film touch panel of the present invention uses a transparent conductive film, the above-mentioned various effects can be better exerted in the touch panel. [Example]

The present invention is further described in detail below by way of examples, but the present invention is not limited to these examples. In addition, various measurements and evaluations in the examples are performed by the following methods. (1) Total light transmittance The total light transmittance was measured using NDH-2000 manufactured by Nippon Denshoku Industries, Ltd. in accordance with JIS-K7361-1:1997.

(2) Surface resistance value Measured by the 4-terminal method in accordance with JIS-K7194:1994. The measuring machine used was Lotesta AX MCP-T370 manufactured by Mitsubishi Chemical Analytech Co., Ltd.

(3) Evaluation of average maximum height The average maximum height is the average of the maximum heights of the five points. The five points are selected by first selecting any point A. Then, one point is selected 1 cm upstream and downstream of A in the length (MD) direction of the film, for a total of two points. Then, one point is selected 1 cm to the left and right of A in the width (TD) direction of the film, for a total of two points. The maximum height is specified in ISO 25178 and is obtained using a 3D surface shape measuring device VertScan (R5500H-M100 manufactured by Ryoka System Co., Ltd. (measurement conditions: wave mode, measurement wavelength 560nm, objective 10x)). In addition, values less than 1nm are rounded off for simplification.

(4) Crystallization degree of transparent conductive film The thin film sample sheet with the transparent conductive thin film layer laminated was cut into 1mm×10mm size and attached to a suitable resin block with the conductive film facing outward. After trimming, ultrathin slices almost parallel to the film surface were made using the technique of a general ultramicrotome. The slices were observed using a transmission electron microscope (JEM-2010, manufactured by JEOL Corporation), and the surface of the conductive film without obvious damage was selected and photographed at an accelerating voltage of 200kV and a direct magnification of 40,000 times. As an evaluation of the crystallinity of the transparent conductive film, the ratio of crystal grains observed under the transmission electron microscope, i.e., the crystallization degree, was observed.

(5) Thickness of transparent conductive film (film thickness) A thin film sample sheet with a laminated transparent conductive thin film layer was cut into a size of 1 mm × 10 mm and buried in an electron microscope epoxy resin. It was fixed to the sample holder of an ultramicrotome, and a cross-sectional thin section parallel to the short side of the buried sample sheet was made. Then, the film thickness was determined from the photographs taken at an accelerating voltage of 200 kV, in a bright field, and at an observation magnification of 10,000 times in the area of the sliced film without obvious damage using a transmission electron microscope (JEOL, JEM-2010).

(6) Pen sliding durability test A transparent conductive film was used as a panel sheet on one side, and a transparent conductive film containing a 20nm thick indium-tin composite oxide film (tin oxide content: 10 mass %) formed by sputtering on a glass substrate was used as a panel sheet on the other side. The two panel sheets were arranged face to face with the transparent conductive films, with epoxy beads of 30μm in diameter interposed therebetween, to produce a touch panel. Next, a load of 2.5N was applied to a polyacetal pen (tip shape: 0.8mmR), and the touch panel was subjected to a straight line sliding test of 50,000 back and forth. The sliding distance at this time was set to 30mm, and the sliding speed was set to 180mm/sec. After this sliding durability test, measure the ON resistance (resistance value when the movable electrode (thin film electrode) and the fixed electrode are in contact) when the sliding part is pressed with a pen load of 0.8N. Ideally, the ON resistance is 10kΩ or less.

(7) Determination of the content of tin oxide in the transparent conductive film. Cut a sample (about 15 ^cm2 ) and put it in a quartz Erlenmeyer flask. Add 20 ml of 6 mol/l hydrochloric acid and seal it with a film to prevent the acid from evaporating. Leave it at room temperature for 9 days while shaking it from time to time to dissolve the transparent conductive film. Take out the remaining film and use the hydrochloric acid that has dissolved the transparent conductive film as the measurement solution. In and Sn in the solution are determined by the calibration curve method using an ICP luminescence analyzer (manufacturer name: Rigaku, device type: CIROS-120 EOP). The measurement wavelength of each element is a wavelength with no interference and high sensitivity. In addition, the standard solution is a diluted commercially available In and Sn standard solution.

(8) Input load test method A transparent conductive film (size: 220 mm × 135 mm) was used as a panel sheet on one side, and a transparent conductive film A including a 20 nm thick indium-tin composite oxide film (tin oxide content: 10 mass %) formed by sputtering on a glass substrate (size: 232 mm × 151 mm) was used as a panel sheet on the other side. On the transparent conductive film A side of the glass substrate with the indium-tin composite oxide film (hereinafter also referred to as ITO glass), epoxy resin (60 μm in length × 60 μm in width × 5 μm in height) was arranged as a dot spacer in a square lattice with a pitch of 4 mm. Next, a double-sided tape (thickness: 105μm, width 6mm) is attached to the transparent conductive film A side of the ITO glass to form a 190mm×135mm rectangle starting from any of the four corners of the ITO glass. Next, the transparent conductive film B side of the transparent conductive film is attached to the double-sided tape attached to the ITO glass, and the transparent conductive film A and the transparent conductive film B are laminated face to face. At this time, one short side of the transparent conductive film is exposed from the ITO glass. Next, the ITO glass and the transparent conductive film are connected with a tester. Next, a load is applied gradually from the transparent conductive film side using a polyacetal pen (tip shape: 0.8 mmR), and the load value when the resistance value measured by the tester is stable is set as the input start load. The position where the load is applied by the pen is the center area surrounded by 4 dot-shaped gaps, and the average value of the input start load at 3 points is calculated. The position where the load is applied by the pen is the center area of 4 dot-shaped gaps as shown in Figure 6. In addition, the input start load is measured at any 3 points more than 50 mm from the double-sided tape and the average value is taken. Decimal points are rounded off.

(9) Film hardness test method Take a 20mm×250mm test piece from a transparent conductive film and place the test piece on a smooth horizontal platform with the transparent conductive layer facing upward. At this time, only the 20mm×20mm part of the test piece is placed on the horizontal platform, and the 20mm×230mm is placed in a manner that is exposed outside the horizontal platform. In addition, a weight is placed on the 20mm×20mm part of the test piece. At this time, the weight and size of the weight are selected in a manner that no gap is formed between the test piece and the horizontal platform. Then, use a ruler to read the difference (=δ) between the height of the horizontal platform and the height of the front end of the film. Then, substitute the value into the following formula (1) to calculate the hardness. 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 platform and the height of the front end of the film

(10) Evaluation of the maximum value of the maximum mountain height and the minimum value of the maximum mountain height relative to the average maximum mountain height The maximum value and the minimum value of the maximum mountain height at the five points measured in the average maximum mountain height evaluation are divided by the average maximum mountain height for calculation.

(11) Adhesion test Implemented in accordance with JIS K5600-5-6:1999. The results in the following table express adhesion in terms of the residual area ratio. The maximum value of the residual area ratio is 100%. The closer the residual area ratio of the adhesion test in the table is to 100%, the smaller the peeling area.

The transparent plastic film substrate used in the Examples and Comparative Examples is a biaxially oriented transparent PET film having an easy-adhesion layer on both sides (manufactured by Toyobo Co., Ltd., A4380, thickness is shown in Table 1 and Table 2). 100 parts by mass of an acrylic resin containing a photopolymerization initiator (SEIKABEAM (registered trademark) EXF-01J manufactured by Dainichi Seika Industries Co., Ltd.) as a curing resin layer was mixed with silicon oxide particles (Snowtex ZL manufactured by Nissan Chemical Co., Ltd.) in the amounts listed in Tables 1 and 2, and a mixed solvent of toluene/MEK (8/2: mass ratio) was added as a solvent so that the solid content concentration became the values listed in Tables 1 and 2, and the mixture was stirred to uniformly dissolve to prepare a coating liquid (hereinafter referred to as coating liquid A). The prepared coating liquid was applied using a Meyer bar so that the coating film thickness became the values listed in Tables 1 and 2. After drying at 80°C for 1 minute, the coating was cured by irradiating with ultraviolet light (light intensity: 300 mJ/cm ² ) using an ultraviolet irradiation device (Eyegraphics, UB042-5AM-W). In addition, under the conditions shown in Tables 1 to 4, a functional layer was provided on the side of the transparent plastic substrate opposite to the curable resin layer.

(Examples 1 to 7) Each example level is implemented in the following manner according to the conditions shown in Table 1. The film is placed in a vacuum chamber and evacuated to 1.5×10 ^-4 Pa. Then, after introducing oxygen, argon is introduced as an inert gas to make the total pressure 0.6 Pa. Electricity is applied to a sintered target of an indium-tin composite oxide or a sintered target of indium oxide without tin oxide at an electric density of 3 W/cm ² to form a transparent conductive film by DC magnetron sputtering. The film thickness is controlled by changing the speed at which the film passes over the target. In addition, the partial pressure ratio of water to inert gas in the film-forming gas environment during sputtering is measured using a gas analyzer (Transpector XPR3, manufactured by Inficon). In each embodiment level, in order to adjust the partial pressure ratio of water to inert gas in the film forming gas environment during sputtering, the presence or absence of the impact step, the height difference of the end surface of the film roll, and the temperature of the temperature medium of the temperature regulating machine that controls the temperature of the center roller on which the film is in contact are adjusted as shown in Table 1. The temperature corresponding to the middle of the maximum and minimum values from the start of film formation to the end of film formation on the film roll is recorded in Table 1 as the center value. The film on which the transparent conductive film is formed and laminated is measured after the heat treatment described in Table 1. The measurement results are shown in Table 1, Table 3 to Table 4.

(Comparative Examples 1 to 7) Using the conditions listed in Table 2, a transparent conductive film was prepared and evaluated in the same manner as in Example 1. The results are shown in Tables 2 to 4.

[Table 1] The center value of (water partial pressure/argon partial pressure) during transparent conductive film formation × 10 ^-3 Oxygen flow/argon flow Temperature control machine center temperature (℃) Bombing steps (*2) Protective film (*3) Height difference of the film roll end surface (mm) Content of tin oxide in transparent conductive film (mass %) Transparent conductive film thickness (nm) Heat treatment conditions Total light transmittance(%) Surface resistance (Ω/□) Embodiment 1 1.40 0.04917 -12 have have 2 3 twenty three 150℃ 60min 87 450 Embodiment 2 1.40 0.04917 -12 have have 2 3 twenty three 150℃ 60min 87 450 Embodiment 3 1.40 0.04917 -12 have have 2 3 twenty three 150℃ 60min 87 450 Embodiment 4 1.40 0.04083 -12 have have 2 36 twenty two 150℃ 60min 86 480 Embodiment 5 1.30 0.04625 -12 have have 2 10 twenty one 150℃ 60min 86.9 250 Embodiment 6 6.90 0.04083 0 have have 9 36 90 150℃ 60min 81 110 Embodiment 7 0.55 0.04167 -12 have have 5 1 13 165℃ 75min 87.5 570 (*1) Hydrogen concentration is calculated as hydrogen ÷ (hydrogen + hydrogen) × 100. (*2) In the blasting step, RF sputtering was performed at 0.5 W/ ^cm2 using SUS (stainless steel) as a target. The amount of gas introduced into the RF sputtering was the same as that introduced into the vacuum apparatus described in the embodiment. (*3) The protective film used was a polyethylene film with a thickness of 65 μm. An acrylic adhesive was applied to one side of the protective film. A protective film is attached to the surface of the film opposite to the surface on which the transparent conductive film is formed.

[Table 2] The center value of (water partial pressure/argon partial pressure) during transparent conductive film formation × 10 ^-3 Oxygen flow/argon flow Temperature control machine center temperature (℃) Bombing steps (*2) Protective film (*3) Height difference of the film roll end surface (mm) Content of tin oxide in transparent conductive film (mass %) Transparent conductive film thickness (nm) Heat treatment conditions Total light transmittance(%) Surface resistance (Ω/□) Comparison Example 1 1.40 0.0408 -12 have have 2 36 twenty three 150℃ 60min 87 450 Comparison Example 2 1.10 0.0492 -12 have have 2 3 twenty three 150℃ 60min 87 450 Comparison Example 3 1.70 0.0492 -12 have have 2 3 twenty three 150℃ 60min 87 450 Comparison Example 4 1.80 0.0492 -12 have have 2 3 twenty three 150℃ 60min 87 450 Comparison Example 5 8.20 0.0492 2 without without 11 45 8 150℃ 60min 88 1400 Comparative Example 6 1.40 0.0083 -12 have have 2 0 110 80℃ 20min 68 1700 Comparison Example 7 1.40 0.0492 -12 have have 2 3 twenty three 150℃ 60min 87 450 (*1) Hydrogen concentration is calculated as hydrogen ÷ (hydrogen + hydrogen) × 100. (*2) In the blasting step, RF sputtering was performed at 0.5 W/ ^cm2 using SUS (stainless steel) as a target. The amount of gas introduced into the RF sputtering was the same as that introduced into the vacuum apparatus described in the embodiment. (*3) The protective film used was a polyethylene film with a thickness of 65 μm. An acrylic adhesive was applied to one side of the protective film. A protective film is attached to the surface of the film opposite to the surface on which the transparent conductive film is formed.

[Table 3] Enter the starting load (g) Average maximum mountain height (μm) Hardness(N‧cm) Formula (2-1) (μm) Maximum value of maximum mountain height/average maximum mountain height Minimum maximum mountain height/average maximum mountain height Thickness of transparent plastic substrate (μm) Presence of hardened resin layer Whether there is a functional layer Inorganic particle addition amount of hardening resin layer (wt%) Solid content concentration of hardened resin layer (%) Embodiment 1 10 4.604 0.57 0.879 1.18 0.83 188 have have twenty three 60 Embodiment 2 5 9.204 0.6 1.020 1.37 0.65 188 have have 29 75 Embodiment 3 15 1.348 0.64 1.208 1.06 0.95 188 have have 15 50 Embodiment 4 14 0.950 0.52 0.644 1.10 0.93 188 have have 10 50 Embodiment 5 12 0.010 0.27 -0.531 1.20 0.90 100 have have 0.1 50 Embodiment 6 15 2.103 0.81 2.007 1.05 0.96 188 have have 18 55 Embodiment 7 11 4.604 0.57 0.879 1.18 0.83 188 have have twenty three 60 Comparison Example 1 17 0.694 0.581 0.931 1.08 0.95 188 have have 27 45 Comparison Example 2 2 0.694 0.158 -1.057 1.08 0.95 50 have have 27 45 Comparison Example 3 34 0.004 0.91 2.477 1.25 0.75 250 without without - - Comparison Example 4 27 0.010 1.12 3.464 1.20 0.90 250 have without 0.1 50 Comparison Example 5 19～21 There is a deviation 0.736 0.56 0.832 1.42 0.59 188 have have 27 55 Comparative Example 6 18 0.694 0.592 0.982 1.07 0.96 188 have have 27 45 Comparison Example 7 0 12.072 0.6 1.020 1.38 0.64 188 have have 30 80

[Table 4] Thickness of hardened resin (μm) Inorganic particle addition amount of functional layer (wt%) Solid content concentration of functional layer (%) Thickness of functional layer (μm) Whether there is an adhesive layer under the hardening resin layer Whether there is an easy-to-attach layer under the functional layer Adhesion test of transparent conductive layer (%) Adhesion test of functional layer (%) Degree of crystallization (%) Pen sliding durability test ON resistance (kΩ) Embodiment 1 5 15 50 6 have have 100 100 100 0.1 Embodiment 2 3 10 60 2 have have 100 100 100 0.1 Embodiment 3 6 20 50 4 have have 100 100 100 0.1 Embodiment 4 5 1 50 6 have have 100 100 0 9 Embodiment 5 5 5 50 6 have have 100 100 0 8 Embodiment 6 13 30 50 15 have have 100 100 0 2 Embodiment 7 5 15 50 6 have have 100 100 70 0.3 Comparison Example 1 5 28 50 6 have have 100 100 0 8 Comparison Example 2 5 27 45 5 have have 100 100 100 13 Comparison Example 3 - - - - without without 10 - 100 ∞ Comparison Example 4 5 - - - have without 100 - 100 0.1 Comparison Example 5 1 15 50 1.5 have have 100 100 0 15 Comparative Example 6 6 27 45 7 have have 100 100 0 0 Comparison Example 7 3 10 60 2 have have 100 100 100 0.1

According to the descriptions in Tables 1 to 4, the input starting load of the transparent conductive film described in Examples 1 to 7 is within the range of the present invention, so it has excellent light operability when used in a resistive film touch panel and excellent pen sliding durability, combining both characteristics. However, Comparative Examples 1 to 7 cannot take into account both light operability and pen sliding durability. [Possibility of industrial use]

As described above, according to the present invention, a transparent conductive film having light operability and excellent pen sliding durability can be provided, which is extremely useful in applications such as resistive film touch panels.

1: Film 2: Center roller 3: Mask 4: Indium-tin composite oxide target 5: Transparent conductive film 6: Curable resin layer 7: Transparent plastic film substrate 8: Functional layer 9: Easy-to-bond layer 10: ITO glass 11: Dot spacer 12: Position where the load is applied with a pen

FIG. 1 is a schematic diagram for explaining the position of a center roll of an example of a sputtering device suitable for use in the present invention. FIG. 2 is a schematic diagram showing a configuration in one embodiment of the present invention. FIG. 3 is a schematic diagram showing a configuration in one embodiment of the present invention. FIG. 4 is a schematic diagram showing a configuration in one embodiment of the present invention. FIG. 5 is a schematic diagram showing a configuration in one embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a measurement position in an input load test method.

without.

Claims (10)

A transparent conductive film is a transparent conductive film having a transparent conductive film of an indium-tin composite oxide laminated on at least one side of a transparent plastic film substrate, wherein the input starting load of the transparent conductive film according to the following input load test is 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 a panel sheet on one side and a transparent conductive film (size: 232 mm×15 An ITO glass having an indium-tin composite oxide film (tin oxide content: 10 mass %) formed by sputtering and having a thickness of 20 nm was used as the panel sheet on the other side. On the indium-tin composite oxide film side of the ITO glass, epoxy resin (length 60 μm × width 60 μm × height 5 μm) was arranged as a square lattice with a pitch of 4 mm. Then, starting from any of the four corners of the ITO glass, a dotted spacer was formed in the shape of a square lattice with a pitch of 4 mm. A double-sided adhesive tape (thickness: 105 μm, width: 6 mm) was attached to the indium-tin composite oxide film side of the ITO glass in a rectangular shape of 190 mm × 135 mm. Next, the transparent conductive film side of the transparent conductive film was attached to the double-sided adhesive tape attached to the ITO glass. The indium-tin composite oxide film of the ITO glass and the transparent conductive film of the transparent conductive film were laminated in a face-to-face manner. At this time, one short side of the transparent conductive film was The ITO glass is exposed from the side. Then, the ITO glass and the transparent conductive film are connected with a tester. Then, a load is applied from the transparent conductive film side with a polyacetal pen with a tip shape of 0.8 mmR. The load value when the resistance value measured by the tester is stable is set as the input start load. The position where the load is applied by the pen is the central area surrounded by 4 dot-shaped gaps. The average value of the input start load at the three points is calculated. The transparent conductive film of claim 1, wherein the softness hardness of the film in the softness hardness test is not less than 0.23 N‧cm and not more than 0.90 N‧cm, and the average maximum height of the conductive surface of the transparent conductive film satisfies the following formula (2-1) and formula (2-2), (film softness hardness test method) A 20 mm × 250 mm test piece is taken from the transparent conductive film, and the test piece is arranged on a flat surface with a transparent conductive layer facing upward. At this time, the test piece is only 20 mm The 20 mm × 20 mm portion of the test piece is placed on the horizontal platform, and the 20 mm × 230 mm portion is placed so as to be exposed outside the horizontal platform. In addition, a weight is placed on the 20 mm × 20 mm portion of the test piece. At this time, the weight and size of the weight are selected so as not to form a gap between the test piece and the horizontal platform. Next, the difference between the height of the horizontal platform and the height of the front end of the film is read using a scale, which is denoted as δ below. Next, the value is substituted into the following formula (1) to calculate the hardness. 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 platform and the height of the front end of the film (average maximum height evaluation)The average maximum height is the average of the maximum heights of the 5 points. The 5 points are selected by first selecting any point as point A, then selecting one point each at 1 cm upstream and downstream of the A point in the length (MD) direction of the film, for a total of 2 points, then selecting one point each at 1 cm to the left and right of the A point in the width (TD) direction of the film, for a total of 2 points, and the maximum height is ISO 25178, the maximum mountain height is determined using a 3D surface shape measuring device VertScan (manufactured by Ryoka System Co., Ltd., R5500H-M100 (measurement conditions: wave mode, measurement wavelength 560nm, objective 10x)). In addition, values less than 1nm are rounded off for simplification. Formula (2-1) Average maximum mountain height (μm) ≧ 4.7 × hardness - 1.8 Formula (2-2) 0.005 (μm) ≦ Average maximum mountain height (μm) ≦ 12.000 (μm). As in claim 2, the maximum value of the maximum mountain height in the average maximum mountain height evaluation is more than 1.0 times and less than 1.4 times the average maximum mountain height, and the minimum value of the maximum mountain height in the average maximum mountain height evaluation is more than 0.6 times and less than 1.0 times the average maximum mountain height. A transparent conductive film as claimed in any one of claims 1 to 3, wherein the thickness of the transparent conductive film is greater than 10 nm and less than 100 nm. A transparent conductive film as claimed in any one of claims 1 to 3, wherein the concentration of tin oxide contained in the transparent conductive film is greater than 0.5 mass % and less than 40 mass %. A transparent conductive film as claimed in any one of claims 1 to 3, wherein a hardened resin layer is provided between the transparent conductive film and the transparent plastic film substrate, and further a functional layer is provided on the side of the transparent plastic substrate opposite to the transparent conductive film. A transparent conductive film as claimed in any one of claims 1 to 3, wherein at least one side of the transparent plastic film substrate has an easy-to-bond layer. As in claim 6, the transparent conductive film, wherein the easy-to-bond layer is disposed at at least one position between the transparent plastic film substrate and the curing resin layer, or between the transparent plastic substrate and the functional layer. A transparent conductive film as claimed in any one of claims 1 to 3, wherein the ON resistance of the transparent conductive film of the transparent conductive film based on the following pen sliding durability test is 10 kΩ or less, (pen sliding durability test) the transparent conductive film is used as a panel sheet on one side, and an ITO glass including an indium-tin composite oxide film (tin oxide content: 10 mass %) with a thickness of 20 nm formed on a glass substrate by sputtering is used as a panel sheet on the other side, and the indium-tin composite oxide film of the ITO glass and the transparent conductive film are transparent. The touch panel was made by placing these two panels face to face with the conductive films interposed between epoxy beads of 30μm in diameter. Then, a load of 2.5N was applied to a polyacetal pen (tip shape: 0.8mmR) and the touch panel was subjected to a straight-line sliding test 50,000 times back and forth. The sliding distance was set to 30mm and the sliding speed was set to 180mm/second. After this sliding durability test, the ON resistance (resistance value when the movable electrode (thin film electrode) and the fixed electrode are in contact) was measured when the sliding part was pressed with a pen load of 0.8N. A transparent conductive film as claimed in any one of claims 1 to 3, wherein the residual area ratio of the transparent conductive film on the surface of the transparent conductive film in the adhesion test according to JIS K5600-5-6:1999 is 95% or more.