JP6681726B2 - Transparent conductive film - Google Patents

Description

  The present invention relates to a transparent conductive film.

  Conventionally, there has been proposed a transparent conductive laminate in which an anti-blocking layer, a color difference adjusting layer and a transparent conductive layer are sequentially laminated on a transparent polymer substrate (for example, refer to Patent Document 1).

  In the transparent conductive laminate described in Patent Document 1, the transparent conductive layer is formed in a pattern having a predetermined shape.

  In Patent Document 1, while the anti-blocking property is ensured by the anti-blocking layer, the difference in pattern visibility is suppressed by the color difference adjusting layer, and the optical properties are ensured.

JP2012-66477A

  However, in Patent Document 1, it is necessary to provide the two layers of the anti-blocking layer and the color difference adjusting layer, which causes a problem that the layer structure becomes complicated. In addition, there is a problem that the device cannot be made thin.

  An object of the present invention is to provide a transparent conductive film having excellent blocking resistance and optical characteristics while simplifying the layer structure and achieving a thin structure.

The present invention (1) includes a transparent substrate, an intermediate layer, and a transparent conductive layer in order, the intermediate layer having a first inorganic particle having an average particle diameter of 30 nm or more and less than 70 nm, and 70 nm or more, A second inorganic particle having an average particle diameter of 140 nm or less, the intermediate layer has a thickness of Dμm, the content ratio of the first inorganic particle in the intermediate layer is 50 mass% or more, 85 The content ratio of the second inorganic particles in the intermediate layer is B mass% or less, the thickness D of the intermediate layer and the content ratio B of the second inorganic particles are the following relational expression (1). (D-82.63) /7.89 <B <(D-55) / 6 (1), which is a transparent conductive film.

  The present invention (2) includes the transparent conductive film according to (1), in which the content B of the second inorganic particles in the intermediate layer is 0.5% by mass or more and 6% by mass or less.

  The present invention (3) includes the transparent conductive film according to (1) or (2), wherein the second inorganic particles have an average particle diameter of 100 nm or less.

  The present invention (4) includes the transparent conductive film according to any one of (1) to (3), wherein the intermediate layer is an anti-blocking optical adjustment layer.

  The present invention (5) includes the transparent conductive film according to any one of (1) to (4), further including a hard coat layer interposed between the transparent substrate and the intermediate layer.

In the present invention (6), the hard coat layer has a plurality of protrusions on its surface, and the maximum protrusion length of the protrusions per cm ^{2 of the} hard coat layer is 200 nm or less. Including a transparent conductive film.

  The present invention (7) includes the transparent conductive film according to any one of (1) to (6), wherein the first inorganic particles are zirconia particles.

  The present invention (8) includes the transparent conductive film according to any one of (1) to (7), wherein the second inorganic particles are silica particles.

  INDUSTRIAL APPLICABILITY The transparent conductive film of the present invention is excellent in blocking resistance and optical properties while simplifying the layer structure and making it thinner.

FIG. 1 shows a cross-sectional view of one embodiment (a mode in which a hard coat layer, an intermediate layer and a transparent conductive layer are provided on a transparent substrate) of the transparent conductive film of the present invention. FIG. 2 shows a modified example of the transparent conductive film shown in FIG. 1 (a mode in which a hard coat layer, an intermediate layer, and a transparent conductive layer are provided above and below a transparent substrate). FIG. 3 shows a modification of the transparent conductive film shown in FIG. 1 (a mode in which an intermediate layer and a transparent conductive layer are provided on a transparent substrate). FIG. 4 shows a modification of the transparent conductive film shown in FIG. 1 (a mode in which an intermediate layer and a transparent conductive layer are provided above and below a transparent substrate). FIG. 5 is a graph showing the relationship between the content B (% by mass) of the second inorganic particles in the intermediate layer and the thickness D (μm) of the intermediate layer in the transparent conductive films of Examples and Comparative Examples. .

  One embodiment of the transparent conductive film of the present invention will be described with reference to FIGS. 1 and 5.

1. Transparent Conductive Film As shown in FIG. 1, the transparent conductive film 1 has a film shape (including a sheet shape) having a predetermined thickness, extends in a predetermined direction (plane direction) orthogonal to the thickness direction, and is flat. An upper surface and a flat lower surface (two main surfaces).

  Specifically, the transparent conductive film 1 includes a transparent base material 2, a hard coat layer 3, an intermediate layer 4, and a transparent conductive layer 5 in order. That is, the transparent conductive film 1 is formed on the transparent base material 2, the hard coat layer 3 provided on the transparent base material 2, the intermediate layer 4 provided on the hard coat layer 3, and the intermediate layer 4. And a transparent conductive layer 5 provided. Preferably, the transparent conductive film 1 is composed only of the transparent substrate 2, the hard coat layer 3, the intermediate layer 4 and the transparent conductive layer 5. Hereinafter, each layer will be described in detail.

2. Transparent Substrate The transparent substrate 2 is a lower layer of the transparent conductive film 1 and is a support layer (support material) that secures the mechanical strength of the transparent conductive film 1. The transparent substrate 2 has a film shape extending in the surface direction and has a flat plane surface and a flat lower surface (two main surfaces).

  The transparent substrate 2 is made of a polymer film. The polymer film has transparency. Examples of the material for the polymer film include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and (meth) acrylic resins (acrylic resin and / or methacrylic resin) such as polymethacrylate, for example, polyethylene, Olefin resin such as polypropylene and cycloolefin polymer (COP), for example, polycarbonate resin, for example, polyether sulfone resin, for example, polyarylate resin, for example, melamine resin, for example, polyamide resin, for example, polyimide resin, for example, cellulose resin Examples include polystyrene resins such as norbornene resins. These polymer films can be used alone or in combination of two or more kinds. From the viewpoint of transparency, mechanical properties, etc., an olefin resin is preferable, and COP is more preferable.

  The thickness of the transparent substrate 2 is, for example, 2 μm or more, preferably 20 μm or more, and for example, 300 μm or less, preferably 200 μm or less.

3. Hard coat layer The hard coat layer 3 is a layer that enhances the scratch resistance of the transparent conductive film 1, and is a layer interposed between the transparent substrate 2 and the intermediate layer 4 described below. The hard coat layer 3 has a film shape extending in the surface direction and has a substantially flat upper surface and a flat lower surface (two main surfaces).

  The hard coat layer 3 has a film shape (including a sheet shape) and is in direct contact with the entire upper surface of the transparent substrate 2.

  The hard coat layer 3 is made of, for example, a known resin composition. Further, the resin composition can also contain particles (particles containing organic particles or inorganic particles) described below in an appropriate ratio.

The hard coat layer 3 may have a plurality of protrusions (not shown) on its upper surface, and the maximum protrusion length of such protrusions per 1 cm ² of the hard coat layer 3 is, for example, 200 nm or less. It is preferably 100 nm or less, more preferably 10 nm or less, and for example, 1 nm or more. When the maximum protrusion length of the protrusion is equal to or less than the above upper limit, the upper surface of the hard coat layer 3 can be made substantially smooth. Therefore, haze can be suppressed.

  The roughness (surface roughness) of the upper surface of the hard coat layer 3 is, for example, 10 nm or less, preferably 5 nm or less, and for example, 0.1 nm or more. The method for measuring the surface roughness of the hard coat layer 3 will be described in Examples below.

  The hard coat layer 3 has a thickness of, for example, 0.1 μm or more, preferably 0.5 μm or more, and for example, 10 μm or less, preferably 5 μm or less.

4. Intermediate Layer The intermediate layer 4 is provided on the upper surface of the hard coat layer 3. The intermediate layer 4 is a layer provided between the hard coat layer 3 and the transparent conductive layer 5 described below. The intermediate layer 4 is a functional layer that imparts functionality according to the purpose. Specifically, the intermediate layer 4 imparts blocking resistance to the transparent conductive film 1, and after the transparent conductive layer 5 is formed into a pattern in a later step, the difference between the non-patterned portion and the patterned portion is different. It is an anti-blocking optical adjustment layer that adjusts the optical properties of the transparent conductive layer 5 so as not to be recognized (that is, to suppress the visual recognition of the pattern).

  The intermediate layer 4 is in direct contact with the entire upper surface of the hard coat layer 3. The intermediate layer 4 has a film shape extending in the plane direction. The intermediate layer 4 has an uneven upper surface (not shown in FIG. 1) caused by the second inorganic particles, which will be described later, and a substantially flat lower surface corresponding to the upper surface of the hard coat layer 3 (two Main surface).

  The mid layer 4 contains first inorganic particles and second inorganic particles.

  Specifically, the mid layer 4 is made of a particle composition containing first inorganic particles and second inorganic particles.

  The particle composition preferably contains the first inorganic particles, the second inorganic particles, and the resin. More preferably, the particle composition comprises only the first inorganic particles, the second inorganic particles, and the resin.

4-1. First Inorganic Particle The first inorganic particle is a small particle having a relatively small average particle diameter among the inorganic particles. The first inorganic particles are optical particles that improve the optical characteristics of the transparent conductive film 1, specifically, optical particles that suppress pattern visibility of the transparent conductive layer 5.

  Examples of the first inorganic particles include silicon oxide (silica) particles such as zirconium oxide (zirconia), titanium oxide (titania), zinc oxide, tin oxide, and other metal oxide particles such as calcium carbonate. Inorganic particles such as salt particles may be mentioned. The first inorganic particles can be used alone or in combination of two or more. The particles are preferably metal oxide particles, more preferably zirconium oxide particles. Zirconium oxide particles are suitable as the first inorganic particles because the refractive index of the film can be easily changed depending on the added amount.

  The first inorganic particles have an average particle size of 30 nm or more and less than 70 nm.

  The first inorganic particles preferably have an average particle size of 35 nm or more, and preferably 60 nm or less, more preferably 50 nm or less.

  When the average particle diameter of the first inorganic particles exceeds the above lower limit, the transparent conductive film 1 becomes a film having excellent adhesion between the transparent conductive layer and the intermediate layer. When the average particle diameter of the first inorganic particles is below the above upper limit, the transparent conductive film 1 can have an excellent appearance.

  The average particle size of the first inorganic particles is the average particle size of the primary particles of the first inorganic particles. Further, preferably, the first inorganic particles are monodisperse particles having a standard deviation of particle size distribution within 10%. Furthermore, the average particle diameter of the first inorganic particles is a volume average particle diameter measured by the BET method.

  The content ratio of the first inorganic particles is 50 mass% or more, preferably 52 mass% or more, and 85 mass% or less, preferably 85 mass% or less with respect to the intermediate layer 4 (that is, the solid content of the particle composition). , 80 mass% or less.

  When the particle composition contains a resin, the content ratio of the first inorganic particles is, for example, 100 parts by mass or more, and preferably 125 parts by mass or more with respect to 100 parts by mass of the resin. For example, it is 800 parts by mass or less, preferably 700 parts by mass or less.

  If the content ratio of the first inorganic particles is less than the above lower limit, the difference in reflectance (ΔR, which will be described later) between the pattern and the non-pattern formed from the transparent conductive layer 5 cannot be reduced, and the transparent conductive layer The pattern visibility of the layer 5 cannot be suppressed.

  When the content ratio of the first inorganic particles exceeds the above upper limit, the reflectance R1 of the transparent conductive layer 5 becomes excessively high, and it is not possible to suppress the pattern visibility of the transparent conductive layer 5.

  On the other hand, when the content ratio of the first inorganic particles is not less than the above lower limit and not more than the above upper limit, it is possible to suppress the pattern visibility of the transparent conductive layer 5.

4-2. Second Inorganic Particle The second inorganic particle is a large particle having a larger average particle diameter than the first inorganic particle among the inorganic particles. The second inorganic particles are blocking resistant particles that impart excellent blocking resistance to the transparent conductive film 1.

  Examples of the second inorganic particles include the inorganic particles exemplified as the first inorganic particles, and preferably silicon oxide particles. Since the silicon oxide particles are low in price and excellent in mechanical strength, it is possible to obtain the high quality transparent conductive film 1 while reducing the manufacturing cost of the transparent conductive film 1.

  The second inorganic particles have an average particle diameter of 70 nm or more and 140 nm or less. The second inorganic particles preferably have an average particle size of more than 70 nm, preferably less than 140 nm, more preferably 130 nm or less, still more preferably 120 nm or less, particularly preferably 110 nm or less, most preferably 100 nm or less. Have a diameter.

  When the average particle diameter of the second inorganic particles exceeds the above lower limit, the transparent conductive film 1 can have excellent blocking resistance. When the average particle diameter of the second inorganic particles is less than the above upper limit, the transparent conductive film 1 can have an excellent appearance.

  The average particle size of the second inorganic particles is the average particle size of the primary particles of the second inorganic particles. Also, preferably, the second inorganic particles are monodisperse particles having a standard deviation of particle size distribution within 10%. Further, the average particle diameter of the second inorganic particles is a volume average particle diameter measured by the BET method.

  The content ratio B of the second inorganic particles in the intermediate layer 4 is set to a ratio that satisfies the relational expression (1) with the thickness D of the intermediate layer 4 described later.

  Specifically, the content ratio B (% by mass) of the second inorganic particles in the intermediate layer 4 and the thickness D (μm) of the intermediate layer 4 satisfy the following relational expression (1).

(D-82.63) /7.89 <B <(D-55) / 6 (1)
On the other hand, when (D-82.63) /7.89≧B is satisfied, the blocking resistance of the transparent conductive film 1 is lowered.

  On the other hand, when B ≧ (D−55) / 6 is satisfied, the haze of the transparent conductive film 1 increases.

  On the other hand, if the content ratio B (% by mass) of the second inorganic particles in the intermediate layer 4 and the thickness D (μm) of the intermediate layer 4 satisfy the above relational expression (1), the transparent conductive film 1 The haze of the transparent conductive film 1 can be reduced while improving the blocking resistance of the.

  As shown in FIG. 5, the content ratio B of the transparent base material 2 increases as the thickness D of the intermediate layer 4 increases. In addition, a range in which the content ratio B of the transparent substrate 2 is allowed (a range surrounded by a straight line showing B = (D-82.63) /7.89 and a line showing B = (D-55) / 6 ) Becomes wider as the thickness D of the intermediate layer 4 increases. Specifically, it is as follows.

(1) If the thickness D of the intermediate layer 4 is 70 μm or more and less than 90 μm , the content ratio B of the second inorganic particles in the intermediate layer 4 is, for example, 0.25% by mass or more, preferably, It is 0.3 mass% or more, more preferably 0.5 mass% or more, still more preferably 0.75 mass% or more, and for example, 4 mass% or less, preferably 2 mass% or less.

(2) If the thickness D of the intermediate layer 4 is 90 μm or more and less than 110 μm , the content ratio B of the second inorganic particles in the intermediate layer 4 is, for example, 1% by mass or more, preferably 3% by mass. % Or more and, for example, 8% by mass or less, preferably 6% by mass or less.

(3) If the thickness D of the intermediate layer 4 is 110 μm or more and 140 μm or less, the content ratio B of the second inorganic particles in the intermediate layer 4 is, for example, 5% by mass or more, preferably 6% by mass. % Or more, more preferably 8% by mass or more, and for example, 12% by mass or less, preferably 10% by mass or less.

  When the content ratio B of the second inorganic particles in (1) to (3) is equal to or more than the above lower limit and is equal to or less than the above upper limit, the transparent conductive film 1 has excellent optical characteristics and blocking resistance. Excel.

  The mixing ratio (ratio) of the second inorganic particles to 100 parts by mass of the first inorganic particles is, for example, 0.1 part by mass or more, preferably 1 part by mass or more, more preferably 3 parts by mass or more, It is preferably 6 parts by mass or more, and for example, 15 parts by mass or less, preferably 10 parts by mass or less.

  Furthermore, when the particle composition contains a resin, the content ratio of the second inorganic particles is, for example, 1 part by mass or more, preferably 5 parts by mass or more, and more preferably 100 parts by mass of the resin. It is 10 parts by mass or more, and is, for example, 86 parts by mass or less, preferably 83 parts by mass or less.

  Furthermore, when the particle composition contains a resin, the content ratio of the total amount of the first inorganic particles and the second inorganic particles (that is, the total content ratio of the inorganic particles) is equal to that of the intermediate layer 4 (that is, the particle composition. Solid content), for example, 55% by mass or more, preferably 57% by mass or more, more preferably 58% by mass or more, still more preferably 59% by mass or more, and particularly preferably 60% by mass or more. And is, for example, 70% by mass or less, preferably 50% by mass or less.

4-3. Resin As the resin, a curable resin, a thermoplastic resin (for example, a polyolefin resin) and the like can be mentioned, and preferably a curable resin can be mentioned.

  Examples of the curable resin include an active energy ray-curable resin that is cured by irradiation with an active energy ray (specifically, an ultraviolet ray or an electron beam), for example, a thermosetting resin that is cured by heating. Preferably, an active energy ray curable resin is used.

  As the active energy ray curable resin, specifically, for example, urethane acrylate, (meth) acrylic ultraviolet curable resin such as epoxy acrylate, for example, urethane resin, for example, melamine resin, for example, alkyd resin, for example, Examples thereof include siloxane-based polymers such as organic silane condensates. A (meth) acrylic UV-curable resin is preferable, and a urethane acrylate is more preferable.

  These resins can be used alone or in combination of two or more kinds.

  The resin content ratio is the balance of the content ratios of the first inorganic particles and the second inorganic particles. Specifically, the content ratio of the resin is, for example, 30% by mass or more, preferably 50% by mass or more, relative to the intermediate layer 4 (that is, the solid content of the particle composition), and, for example, 45%. The amount is not more than 40% by mass, preferably not more than 43% by mass, more preferably not more than 42% by mass, further preferably not more than 41% by mass, particularly preferably not more than 40% by mass.

4-4. Roughness of Intermediate Layer The roughness (surface roughness) of the upper surface of the intermediate layer 4 is, for example, 10 nm or less, preferably 6 nm or less, and for example, 0.5 nm or more, preferably 1 nm or more.

4-5. Thickness of the intermediate layer D
The thickness D of the mid layer 4 is set to a thickness that satisfies the above relational expression (1) together with the content ratio B of the second inorganic particles.

The thickness D of the intermediate layer 4 is, for example, 55 μm or more, preferably 80 μm or more, and for example, 140 μm or less, preferably while satisfying the above relational expression (1). , 120 μm or less, and more preferably 105 μm or less.

  When the thickness D of the intermediate layer 4 exceeds the above lower limit, the reflectance difference (ΔR) between the pattern formed from the transparent conductive layer 5 and the non-pattern can be reduced, and the pattern visibility of the transparent conductive layer 5 can be suppressed. can do. When the thickness D of the mid layer 4 is less than the above upper limit, the reflection tint can be made closer to neutral.

  A method for measuring the thickness of the mid layer 4 will be described in Examples below.

4-6. Physical Properties of Intermediate Layer The haze of the intermediate layer 4 is, for example, less than 0.4, preferably 0.3 or less, more preferably 0.25 or less, still more preferably 0.2 or less, and particularly preferably 0. If the haze of the intermediate layer 4 is less than the above upper limit, the transparent conductive film 1 has excellent optical characteristics.

  The method for measuring the haze of the mid layer 4 will be described in Examples below.

4-7. Method for Producing Intermediate Layer To produce the intermediate layer 4, for example, first, the particle composition described above is prepared. Preferably, the first inorganic particles, the second inorganic particles, the resin and the solvent are mixed to prepare a particle composition solution (coating liquid, intermediate layer forming coating liquid).

  Examples of the solvent include organic solvents, and such organic solvents are not particularly limited, and examples thereof include alcohol solvents such as methanol, isopropyl alcohol, butanol, ethylene glycol, ethylene glycol monopropyl ether, and propylene glycol monomethyl ether. Examples thereof include ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, and aromatic solvents such as xylene and toluene.

  To prepare the particle composition solution (coating solution), for example, a particle resin mixture in which a resin and one of the first inorganic particles and the second inorganic particles are mixed in advance is prepared, and the particle resin mixture is prepared. , And the other (inorganic particles). At this time, the solvent may be blended with any of the above-mentioned raw materials (either the resin, the first inorganic particles, or the second inorganic particles).

  Alternatively, first, a resin and a solvent are mixed to prepare a resin solution, and then the resin solution is mixed with the first inorganic particles and the second inorganic particles. Further, the resin is blended with the first inorganic particles, the second inorganic particles and the solvent.

  Preferably, a particle resin mixture (particle composition solution) in which a resin, first inorganic particles, and a solvent are mixed in advance is prepared, and then the particle resin mixture (particle composition solution) is mixed with the second inorganic particles. To do.

  In addition, as the particle resin mixture (particle composition solution) in which the first inorganic particles are preliminarily blended, a commercially available product can be used, and specifically, OPSTAR series (manufactured by JSR Corporation) or the like is used.

  Further, known additives (including organic particles such as crosslinked acrylic resin particles) can be added to the particle composition solution at an appropriate ratio, for example, as long as the effects of the present invention are not impaired.

  Then, the particle composition solution is applied to the entire upper surface of the hard coat layer 3.

  Then, the solvent is removed by heating. The heating temperature is, for example, 50 ° C. or higher, preferably 55 ° C. or higher, and for example, 100 ° C. or lower, preferably 80 ° C. or lower. The heating time is, for example, 10 seconds or more, preferably 20 seconds or more, and is, for example, 5 minutes or less, preferably 3 minutes or less.

  As a result, a coating film made of the particle composition is formed.

  Then, when the particle composition contains an active energy ray-curable resin, the coating film is irradiated with active energy rays. This cures the resin.

  Thereby, the intermediate layer 4 is formed on the upper surface of the hard coat layer 3.

  The first inorganic particles and the second inorganic particles contained in the mid layer 4 are qualitatively analyzed (identified) by, for example, burning the mid layer 4 and then elementally analyzing the obtained ash. The first inorganic particles and the second inorganic particles are quantitatively analyzed by measuring the particle size of the first inorganic particles and the second inorganic particles with a laser diffraction type particle size distribution measuring device or the like. In the above-mentioned quantitative analysis, a particle size distribution curve having two peaks based on two average particle diameters (median diameters) of the first inorganic particles and the second inorganic particles is obtained, and from the peaks, the first inorganic particles and the second inorganic particles can be obtained. The average particle size and blending ratio of the second inorganic particles are obtained, respectively.

5. Transparent Conductive Layer The transparent conductive layer 5 is an upper layer of the transparent conductive film 1 and is a conductive layer for forming a pattern portion (not shown) in a pattern in a later step. The transparent conductive layer 5 has a film shape (including a sheet shape) extending in the surface direction, and has a flat lower surface and a flat upper surface. The transparent conductive layer 5 is in direct contact with the entire upper surface of the intermediate layer 4.

  The material for forming the transparent conductive layer 5 is, for example, at least selected from the group consisting of In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, and W. A metal oxide containing one kind of metal may be mentioned. If necessary, the metal oxide can be further doped with a metal atom shown in the above group.

  The material is preferably indium tin composite oxide (ITO), antimony tin composite oxide (ATO), and the like, and more preferably ITO.

  The transparent conductive layer 5 has a thickness of, for example, 10 nm or more, preferably 20 nm or more, and for example, 35 nm or less, preferably 30 nm or less.

  The transparent conductive layer 5 is formed on the entire upper surface of the intermediate layer 4 by a known method.

  Thereby, the transparent conductive film 1 including the transparent substrate 2, the hard coat layer 3, the intermediate layer 4, and the transparent conductive layer 5 in order is obtained.

6. Manufacturing Method and Physical Properties of Transparent Conductive Film This transparent conductive film 1 is obtained by sequentially disposing the hard coat layer 3, the intermediate layer 4 and the transparent conductive layer 5 on the upper side of the transparent substrate 2. The method for producing the transparent conductive film 1 is performed by a roll-to-roll method. Further, a part or the whole can be carried out in a batch system.

  The reflectance R1 of the transparent conductive layer 5 of the transparent conductive film 1 is, for example, 10% or less, preferably 9% or less, more preferably 8% or less, further preferably 7% or less, and particularly preferably 6%. % Or less, and for example, exceeds 0%.

  When the reflectance R1 in the transparent conductive layer 5 of the transparent conductive film 1 is below the above-mentioned upper limit, the visibility of the display when commercialized can be improved, and the transparent conductive film 1 has excellent optical characteristics.

  The thickness of the transparent conductive film 1 is, for example, 200 μm or less, preferably 150 μm or less, and for example, 20 μm or more, preferably 30 μm or more.

5. Use of transparent conductive film Such a transparent conductive film 1 is provided, for example, in an image display device.

  In particular, this transparent conductive film 1 is used, for example, as a base material for a touch panel. As the format of the touch panel, various systems such as an optical system, an ultrasonic system, an electrostatic capacitance system, and a resistive film system can be mentioned. The transparent conductive film 1 is particularly preferably used for a capacitive touch panel.

  Specifically, first, the transparent conductive layer 5 of the transparent conductive film 1 is removed by, for example, etching to form a pattern portion (not shown) and a non-pattern portion (not shown). .

  The reflectance difference ΔR between the patterned portion and the non-patterned portion of the transparent conductive film 1 is an absolute value thereof, for example, 2 or less, preferably 1.5 or less, more preferably 1.0 or less, and further preferably , 0.5 or less. When the reflectance difference ΔR is equal to or less than the above upper limit, it is possible to suppress visual recognition in the pattern portion of the transparent conductive layer 5.

  The reflectance difference ΔR in the transparent conductive film 1 is a value obtained by subtracting the reflectance R2 of the non-patterned portion from the reflectance R1 of the patterned portion, and, for example, by the method described in JP-A-2005-166184 or the like. Desired.

  Then, the transparent conductive film 1 is provided in the image display device described above.

6. Function and Effect In this transparent conductive film 1, the content ratio of the first inorganic particles in the intermediate layer 4 is 50% by mass or more and 85% by mass or less, and the thickness D of the intermediate layer 4 and the content of the second inorganic particles are contained. The ratio B satisfies the following relational expression (1).

(D-82.63) /7.89 <B <(D-55) / 6 (1)
Therefore, it has excellent blocking resistance and optical characteristics.

  On the other hand, in Patent Document 1, it is necessary to provide two layers, an anti-blocking layer and a color difference adjusting layer, which causes a problem that the layer structure becomes complicated.

  However, in this transparent conductive film 1, since the intermediate layer 4 is a blocking-resistant optical adjustment layer, while reliably imparting blocking resistance to the transparent conductive film 1, it is possible to ensure visual recognition of the pattern in the transparent conductive layer 5. Can be suppressed.

  As a result, the layer structure is simplified, the thickness is reduced, and the blocking resistance and the optical characteristics are excellent.

  Further, in this transparent conductive film 1, if the content ratio B of the second inorganic particles is 0.3% by mass or more, and further 0.5% by mass or more and 3% by mass or less, the transparent conductive film 1 Has even better optical properties.

  Further, in this transparent conductive film 1, if the average particle size of the second inorganic particles is 100 nm or less, the transparent conductive film 1 can have an excellent appearance.

  Moreover, since the transparent conductive film 1 includes the hard coat layer 3, the scratch resistance of the transparent conductive film 1 can be enhanced.

Further, in this transparent conductive film 1, the hard coat layer 3 has a plurality of protrusions on its surface, and if the maximum protrusion length of the protrusions per 1 cm ² of the hard coat layer is 200 nm or less, the hard coat layer 3 The smoothness of the layer 3 can be ensured.

  On the other hand, in that case, the transparent conductive film 1 is easily blocked due to the smoothness of the hard coat layer 3. That is, the blocking resistance of the transparent conductive film 1 is reduced.

  However, in this transparent conductive film 1, the intermediate layer 4 has the second inorganic particles having an average particle diameter of 70 nm or more and 140 nm or less, the relationship between the content ratio B of the second inorganic particles and the thickness D of the intermediate layer 4. Since it is contained so as to satisfy the formula (1), blocking resistance can be secured.

  In addition, in the transparent conductive film 1, if the first inorganic particles are zirconia particles, optical adjustment can be easily performed.

  Further, in this transparent conductive film 1, if the second inorganic particles are silica particles, it is possible to obtain a high quality transparent conductive film 1 while reducing the manufacturing cost of the transparent conductive film 1.

7. Modified Example In the embodiment shown in FIG. 1, the transparent conductive film 1 includes the hard coat layer 3, the intermediate layer 4, and the transparent conductive layer 5 which are arranged only on the upper side of the transparent substrate 2. However, the arrangement of the hard coat layer 3, the intermediate layer 4 and the transparent conductive layer 5 is not limited to the above, and for example, as shown in FIG. The coat layer 3, the intermediate layer 4, and the transparent conductive layer 5 may be provided.

  The modification shown in FIG. 2 can also achieve the same effects as those of the embodiment shown in FIG.

  Moreover, in the embodiment shown in FIG. 1, the transparent conductive film 1 includes a hard coat layer 3. However, as shown in FIG. 3, the transparent conductive film 1 may not include the hard coat layer 3 and may include only the transparent substrate 2, the intermediate layer 4, and the transparent conductive layer 5 in order. In this modification, the transparent conductive film 1 is preferably composed of only the transparent substrate 2, the intermediate layer 4 and the transparent conductive layer 5. The intermediate layer 4 is arranged on the upper surface of the transparent substrate 2. Specifically, the intermediate layer 4 is in direct contact with the entire upper surface of the transparent substrate 2.

  The modified example shown in FIG. 3 can also achieve the same effect as that of the embodiment shown in FIG.

  Further, as shown in FIG. 4, the transparent conductive film 1 may include an intermediate layer 4 and a transparent conductive layer 5 which are sequentially arranged on the upper and lower sides of the transparent substrate 2.

  The modification shown in FIG. 4 can also achieve the same effects as the embodiment shown in FIG.

  It is also possible to combine the modifications described above as appropriate.

  For example, as shown in FIG. 1, a hard coat layer 3, an intermediate layer 4 and a transparent conductive layer 5 are provided on the upper side of the transparent substrate 2, while as shown in FIG. It is also possible to provide only the intermediate layer 4 and the transparent conductive layer 5 on the lower side.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the examples and comparative examples. Further, specific numerical values such as a mixing ratio (content ratio), a physical property value, and a parameter used in the following description are described in the above-mentioned “Mode for carrying out the invention”, and a corresponding mixing ratio ( Substitute the upper limit (value defined as "below" or "less than") or the lower limit (value defined as "greater than or equal to" or "exceeded") of the corresponding description such as content ratio), physical property value, parameter, etc. be able to.

(Preparation of coating liquid)
Preparation example 1
A particle resin mixture in which urethane acrylate as an ultraviolet curable resin and zirconia particles having an average particle diameter of 60 nm as a first inorganic particle are pre-blended (manufactured by JSR, product name "OPSTAR KZ6732", content ratio of first inorganic particle: 57 mass). %) And an organosilica sol (manufactured by Nissan Kagaku Co., Ltd., product name “MEK-ST-ZL”) in which silica particles having an average particle diameter of 70 to 100 nm as second inorganic particles are dispersed in methyl ethyl ketone. The coating solutions (coating solutions for forming the intermediate layer) were prepared by mixing in the proportions.

Preparation Example 2 to Comparative Preparation Example 7
A coating liquid (coating liquid for forming an intermediate layer) was prepared in the same manner as in Preparation Example 1 except that the blending ratio was changed as described in Table 1.

Example 1
As a transparent substrate 2, a 100 μm-thick COP film (ZEONOR ZF-16, manufactured by Zeon Corporation) was provided with a 1 μm-thick hard coat layer 3 made of an organic-inorganic hybrid resin (KZ6506 JSR) on the upper surface.

Then, the coating liquid of Preparation Example 1 was applied on the upper surface of the hard coat layer 3 with a spin coater at 2000 rpm for 10 seconds, and dried in a drying oven at 60 ° C. for 30 seconds to volatilize the solvent (methyl ethyl ketone). To form a coating film. Thereafter, a coating film, using an oxygen concentration 2500ppm atmosphere at 160 W / cm ² of air-cooled mercury lamp (manufactured by Eye Graphics Co., Ltd.), ultraviolet illuminance 60 mW / cm ^2, was irradiated with irradiation dose 280 mJ / cm ² , The coating was cured.

Thereby, the intermediate layer 4 having a thickness D of 85 μm was formed on the upper surface of the hard coat layer 3.

  Then, a transparent conductive layer 5 made of ITO having a thickness of 25 nm was formed on the upper surface of the intermediate layer 4.

(Evaluation)
The following items were measured. Table 1 shows the results.

(Thickness of the intermediate layer)
The thickness D of the intermediate layer 4 was obtained from the peak wavelength of the reflection spectrum obtained by a spectrophotometer (model number “U4100”, manufactured by Hitachi High-Technologies Corporation).

(Blocking resistance)
A COP film (ZEONOR film ZF-16, manufactured by Nippon Zeon Co., Ltd.) was pressed against the intermediate layer 4 with a finger, the degree of sticking was observed, and the blocking resistance was evaluated according to the following criteria.
◯: No sticking of the COP film occurs.
Δ: COP film sticking occurs once, but after 10 seconds, the COP film separates from the mid layer 4.
X: Sticking of the COP film occurred, and the COP film did not separate from the mid layer 4 even after 10 seconds had elapsed.

(Haze of the middle layer)
The haze of the transparent conductive film 1 before the formation of the intermediate layer 4 and the transparent conductive layer 5 was measured by a haze meter (HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.).

  Then, a value obtained by subtracting the haze values of the transparent substrate 2 and the hard coat layer 3 from the haze value was determined as the haze of the intermediate layer.

(Surface roughness of hard coat layer and intermediate layer)
The surface roughness of each of the hard coat layer 3 and the intermediate layer 4 was determined by AFM (manufactured by Digital Instruments).

(Difference in reflectance of transparent conductive layer)
The transparent conductive layer 5 was etched to form a pattern portion and a non-pattern portion.

  After that, using an integrating sphere measurement mode of a spectrophotometer (“U-4100”, manufactured by Hitachi High-Tech Co., Ltd.), the incident angle to the transparent conductive layer 5 was set to 2 degrees, and the pattern portion and non-pattern area in the wavelength range of 380 to 780 nm were used. The reflectance with the pattern portion was measured at 5 nm intervals. Next, the average reflectance R1 of the pattern portion and the average reflectance R2 of the non-pattern portion are calculated, and the pattern portion (the transparent base material 2, the hard coat layer 3, the intermediate layer 4 and the transparent conductive layer is calculated from these average reflectance values. 5) and the reflectance difference ΔR (= R1-R2) between the non-patterned portion (the transparent substrate 2, the hard coat layer 3, and the intermediate layer 4) were calculated.

1 Transparent Conductive Film 2 Transparent Substrate 3 Hard Coat Layer 4 Intermediate Layer 5 Transparent Conductive Layer

Claims (8)

A transparent substrate, an intermediate layer, and a transparent conductive layer are sequentially provided,
The intermediate layer is
First inorganic particles having an average particle diameter of 30 nm or more and less than 70 nm,
Including second inorganic particles having an average particle diameter of 70 nm or more and 140 nm or less,
The intermediate layer has a thickness of D μm,
The content ratio of the first inorganic particles in the intermediate layer is 50% by mass or more and 85% by mass or less,
The content ratio of the second inorganic particles in the intermediate layer is B mass%,
The transparent conductive film (D-82.63) /7.89 <B, wherein the thickness D of the intermediate layer and the content B of the second inorganic particles satisfy the following relational expression (1). <(D-55) / 6 (1).   Content ratio B of the said 2nd inorganic particle in the said intermediate | middle layer is 0.5 mass% or more and 6 mass% or less, The transparent conductive film of Claim 1 characterized by the above-mentioned.   The transparent conductive film according to claim 1 or 2, wherein the average particle diameter of the second inorganic particles is 100 nm or less.   The transparent conductive film according to any one of claims 1 to 3, wherein the intermediate layer is an anti-blocking optical adjustment layer.   The transparent conductive film according to any one of claims 1 to 4, further comprising a hard coat layer interposed between the transparent base material and the intermediate layer. The hard coat layer has a plurality of protrusions on its surface,
The transparent conductive film according to claim 5, wherein the maximum protrusion length of the protrusion per cm ^{2 of the} hard coat layer is 200 nm or less.   The said 1st inorganic particle is a zirconia particle, The transparent conductive film as described in any one of Claims 1-6 characterized by the above-mentioned.   The said 2nd inorganic particle is a silica particle, The transparent conductive film as described in any one of Claims 1-7 characterized by the above-mentioned.

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