JP6308572B1 - Transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film that makes it difficult to visually recognize a wiring pattern by an ITO layer. SOLUTION: At least a first hard coat layer, an optical adjustment layer, and an inorganic layer are provided on one surface of a base film on a surface opposite to the second hard coat layer lamination surface of the base film. And a transparent conductive layer, the first hard coat layer is made of an ultraviolet curable resin, the second hard coat layer is made of an ultraviolet curable resin, and the inorganic layer is made of silicon oxide. And the refractive index is 1.4 or more and 1.5 or less, and the transparent conductive layer is a transparent conductive film made of crystallization type indium tin oxide (ITO), and the light transmitted through the transparent conductive film The transparent conductive film was characterized in that b * of the transmitted hue was 1.5 or less. [Selection figure] None

Description

  The present invention relates to a transparent conductive film, and more specifically, to a transparent conductive film that can suppress surface color unevenness visibility.

  In recent years, a wide variety of products using touch panels have become widespread in various daily lives. For example, it is used for bank ATMs, railway ticket machines, car navigation display units, office copy machine operation units, etc., and also for image / information display parts in portable small mobile devices such as mobile phones. A touch panel is also used to serve as an operating device portion.

  The touch panel uses a transparent conductive film in which a transparent conductive layer is laminated on a transparent substrate as an electrode, and is used as a touch panel display by being bonded to a display device such as a liquid crystal display. Indium tin composite oxide (ITO) is widely used as the transparent wiring formed in the transparent conductive layer. That is, an ITO layer is patterned into a wiring pattern to form a transparent conductive layer, and a laminate thereof is provided as a transparent conductive film.

  In such a transparent conductive film, the ITO layer and the transparent film used as the base material of the transparent conductive film have different refractive indexes, so that the wiring pattern of the conventional ITO layer is easily visible. There was a problem.

  Therefore, as a countermeasure, for example, as seen in the invention described in Patent Document 1, for example, an optical adjustment layer is provided between the ITO layer and the transparent substrate film. By doing so, there is also an example in which the reflectance of the transparent conductive film is attempted to be low from the viewpoint of visibility.

  Moreover, as seen in the invention described in Patent Document 2, there is an example in which this problem is solved by providing an anti-blocking layer containing particles between the base film and the ITO layer.

JP 2013-025737 A JP2015-005272A

  However, when it is configured as shown in Patent Document 1, since the transparent conductive film is generally not a complete colorless transparent laminate, the surface of the film is inevitably caused by trying to reduce the reflectance of the transparent conductive film obtained. If the configuration of Patent Document 1 is used, the probability of occurrence of color unevenness due to variations in the thickness of the color tone correction layer is increased. At the same time as the color unevenness, there is a problem that if the wiring pattern of the ITO layer is tried to reduce the reflectance, the pattern becomes easy to visually recognize. In particular, when such a film is used for an organic electroluminescence (OLED) panel whose use is expected to be expanded recently, the polarizing plate is positioned on the outermost surface, and thus low retardation is required. In the invention described in the above, it was not possible to sufficiently cope with the problem. Also, in the case of forming a wiring, if it is used for an OLED, a phenomenon in which the wiring is easily seen can be seen unless an effective optical adjustment layer is provided, which can be said to be a problem.

  That is, even with these inventions, it can be said that it has been difficult to avoid the problem that the wiring pattern of the ITO layer is easily visible even when a transparent conductive film is used for the touch panel display.

  Moreover, when it is set as the structure which is seen by patent document 2, the raised part resulting from particle | grains and the flat part which is not so arise in an antiblocking layer, The level | step difference is smooth | smooth required for a transparent conductive film May not be a preferable solution.

  The present invention has been made in view of such problems, and the purpose thereof is even when used in a display such as an OLED, which makes it difficult to visually recognize a wiring pattern by an ITO layer. It is to provide a transparent conductive film in which a wiring pattern is hardly visible.

In order to solve the above problems, in the transparent conductive film according to claim 1 of the present invention, the second hard coat layer is opposite to the second hard coat layer lamination surface of the base film on one side of the base film. A transparent conductive film in which at least a first hard coat layer, an optical adjustment layer, an inorganic layer, and a transparent conductive layer are laminated on the surface in the described order and in a state where each layer is in contact with each other. A transparent conductive film formed by laminating, wherein the first hard coat layer is made of an ultraviolet curable resin, the second hard coat layer is made of an ultraviolet curable resin, and the inorganic layer is made of silicon oxide. The refractive index is 1.4 or more and 1.5 or less, and the transparent conductive layer is a transparent conductive film made of crystallization type indium tin oxide (ITO), and the transparent conductive layer The b * of the transmitted hue of the light transmitted through the film is 1.5 or less, and the second hard coat layer is added to an ultraviolet curable resin with an inorganic filler having an average major axis of 1.5 μm or more and 3.0 μm or less. It is characterized by that.

The transparent conductive film according to claim 2 of the present invention is the transparent conductive film according to claim 2, wherein the inorganic filler is any one of silicon oxide, zirconium oxide, titanium oxide, or niobium oxide. It is characterized by being.

The transparent conductive film according to claim 3 of the present invention is the transparent conductive film according to claim 1 or 2 , wherein the optical adjustment layer is obtained by adding an inorganic filler to an ultraviolet curable resin. It is characterized by.

In the transparent conductive film of Claim 4 of this invention, It is a transparent conductive film of any one of Claim 1 thru | or 3 , Comprising: The said base film is 20 micrometers or more and 100 micrometers or less in thickness. It is a cycloolefin film, the thickness of the first hard coat layer and the second hard coat layer are both 0.5 μm or more and 1.5 μm or less, and the thickness of the optical adjustment layer is 50 nm or more and 150 nm or less. The inorganic layer is a layer made of silicon oxide having a thickness of 2 nm or more and 10 nm or less, the transparent conductive layer is a thickness of 15 nm or more and 50 nm or less, and a resistance value is 50Ω / □ or more and 200Ω / □ or less, Features.

The transparent conductive film according to claim 5 of the present invention is the transparent conductive film according to any one of claims 1 to 4 , wherein the surface of the second hard coat layer is further antistatic. It is characterized in that a protective film having a function is attached.

  If the transparent conductive film according to the present invention includes an optical adjustment layer and an inorganic layer made of silicon oxide in its configuration, these two layers control the hue of the transparent conductive film according to the present invention. Thus, for example, it is possible to solve the problem that the circuit part is lifted and seen halfway during actual use, or the visibility is hindered.

  Embodiments of the present invention will be described below. Note that the embodiment shown here is merely an example, and is not necessarily limited to this embodiment.

(Embodiment 1)
The transparent conductive film according to the present invention will be described as a first embodiment.

  The transparent conductive film according to the present embodiment has a second hard coat layer on one side of the base film, and at least a first hard coat layer on the surface opposite to the second hard coat layer lamination surface of the base film. And an optical adjustment layer, an inorganic layer, and a transparent conductive layer.

  In the following description, the first hard coat layer and the second hard coat layer are made of an ultraviolet curable resin, the inorganic layer is made of silicon oxide, and the refractive index is 1.4 or more and 1.5 or less. Furthermore, the transparent conductive layer is a transparent conductive film that is a crystallized type indium tin oxide (ITO), and b * of the transmission color of light transmitted through the transparent conductive film is 1.5 or less, However, it should be noted in advance that the present invention is not necessarily limited to this.

Hereinafter, the description will be made in order.
First, the base film is a so-called transparent base film. That is, since it is assumed that the transparent conductive film according to the present embodiment is attached to a surface of a liquid crystal display such as a smartphone, for example, it is preferably transparent.

  In addition, when it is assumed to be used for such applications, for example, it is preferable to use a cycloolefin film, particularly a cycloolefin polymer (COP) film, and further a low retardation type COP film. A low retardation type COP film (hereinafter also simply referred to as “COP film”) is used as a base film. This is because the transparent conductive film according to the present embodiment aims to reduce the retardation. That is, if the film used as the substrate is a low retardation film having a small birefringence, it becomes easy to impart the property of low retardation to the transparent conductive film to be obtained.

  If such conditions can be realized, it is possible to use a transparent base film generally used in a conventionally known transparent conductive film, more specifically, a transparent polymer resin film. This is because the transparent conductive film according to the present embodiment can be easily used for various surfaces, planes, and curved surfaces. As such a transparent polymer resin film, in addition to the COP film described above, for example, a polyethylene terephthalate (PET) film, a polycarbonate film, a polyethylene naphthalate film, a norbornene film, and the like can be considered.

  The thickness of the base film (COP film) in the present embodiment is preferably 20 μm or more and 100 μm or less. If the thickness of the substrate film is greater than 100 μm, the number of pieces that can be processed at one time is reduced, workability is deteriorated and costs are increased, and the entire thickness of the transparent conductive film is undesirably increased. However, if the substrate is made thinner than necessary, the substrate itself is damaged when a laminate described later is laminated, or a display or the like is manufactured using the obtained transparent conductive film according to the present embodiment. Since the film is immediately damaged in the scene, that is, the function as the transparent conductive film is damaged, a thickness of 20 μm or more is necessary. Here, in order to make the entire transparent conductive film according to the present embodiment low retardation, it is more preferably 30 μm or more and 50 μm or less. In this embodiment, it is 40 μm.

  The base film according to the present embodiment has no problem even if a layer to be described later is laminated on the surface as it is, for example, when a COP film is used as the base film. In the case of using a film such as a PET film, for example, as a base film, an easy adhesion layer may be provided on either surface or both surfaces. By having an easy-adhesion layer, the adhesive force of a base film and the 1st hard-coat layer and 2nd hard-coat layer which are mentioned later improves, and the fall of durability by delamination etc. can be prevented. At this time, if the easy adhesion layer to be provided is set within a desired and suitable range, interference fringes caused by a difference in refractive index from the first hard coat layer and the second hard coat layer described later can be more reliably prevented. And a better appearance can be obtained.

Next, the first hard coat layer will be described.
The first hard coat layer according to the present embodiment may be made of a resin that has been conventionally used as a hard coat layer in order to improve the hardness of the obtained transparent conductive film and increase the scratch resistance. . For example, a polyfunctional acrylate resin that is an ultraviolet curable resin, a urethane acrylate resin, an inorganic organic hybrid resin, a polyester acrylate resin, a melamine resin that is a thermosetting resin, a urethane resin, and the like. Further, this hard coat layer is preferable if the light refractive index n is 1.45 or more and 1.65 or less. By having a refractive index in such a range, interference fringes caused by the refractive index difference can be prevented, and the visibility of the transparent conductive film obtained can be improved.

  The hard coat layer in this embodiment uses an ultraviolet curable resin. This is laminated | stacked on the surface of a base film by coating, and a hard-coat layer is obtained by performing ultraviolet curing then. The film thickness after curing is preferably 0.5 μm or more and 1.5 μm or less, and is 1.3 μm in the present embodiment. If the thickness is less than 0.5 μm, the scratch resistance necessary for preventing scratches during conveyance or the like cannot be obtained, and the required characteristics cannot be satisfied. When the film thickness is thicker than 1.5 μm, curling occurs due to stress, resulting in poor handling and difficulty in processing.

  The first hard coat layer in the present embodiment may contain other additives. Specific examples include photopolymerization initiators, curing agents, curing accelerators, crosslinking agents, solvents, reactive diluents, photosensitizers, surface conditioners, and slip agents.

  The second hard coat layer in the present embodiment may be equivalent to the first hard coat layer described above. That is, an ultraviolet curable resin is used in the present embodiment, and the thickness after curing is preferably 0.5 μm or more and 1.5 μm or less, and 1.3 μm in this embodiment.

  In the present embodiment, it may be considered that the second hard coat layer contains an inorganic filler. By including it in the second hard coat layer, it is beneficial to make the transportability and winding property of the transparent conductive film according to the present embodiment suitable.

  In this embodiment, it can be said that it is preferable to use, for example, silicon oxide, zirconium oxide, titanium oxide, niobium oxide, or the like as the inorganic filler. Here, a silicon oxide filler is used. Moreover, although it is the magnitude | size, it is preferable that an average major axis is 1.5 to 3.0 micrometer. In the present embodiment, the second hard coat layer is made to contain an inorganic filler having an average major axis of 1.7 μm in consideration of transportability and winding property.

  Furthermore, in order to perform finer optical adjustment, it is conceivable to include the same inorganic filler in the first hard coat layer, but further details are omitted here.

Next, the optical adjustment layer will be described.
The optical adjustment layer in the present embodiment is provided in order to improve interlayer adhesion, and at the same time, in the present embodiment, it is also necessary for exhibiting an important effect of optical adjustment of the entire transparent conductive film. Layer.

  The material used may be a conventionally known material, and an ultraviolet curable resin or the like can be suitably used, and this is also used in this embodiment. This optical adjustment layer is laminated by a so-called wet coating method. The thickness is preferably 50 nm or more and 150 nm or less after the resin is cured as described above, and is 90 nm in the present embodiment.

  This optical adjustment layer is also more preferable by adjusting the light refractive index to obtain a transparent conductive film more suitable for transparency. If it considers simply, it can be said that it will become easy to improve visibility if the b * value of this optical adjustment layer is suppressed.

  That is, by stacking two layers of the optical adjustment layer and the inorganic layer described later, the hue can be controlled more effectively by the correlation between the optical refractive index of the optical adjustment layer and the optical refractive index of the inorganic layer. Therefore, if the optical refractive index of the optical adjustment layer is adjusted so as to be within a desired numerical range, a more preferable transparent conductive film with a uniform transparency up to a level where the presence of color eyes cannot be visually recognized. You can get it. An effective refractive index in the present embodiment is preferably within a range called a so-called medium refractive index.

  Further, in order to more easily achieve the purpose of optical adjustment, it can be considered that zirconia fine particles are contained in this layer, but the detailed description thereof is omitted here.

  Next, in this embodiment, an inorganic layer is provided before the transparent conductive layer is laminated on the surface of the optical adjustment layer. Therefore, this inorganic layer will be described.

  The inorganic layer in the present embodiment uses silicon oxide (SiOx). As a result, interlayer adhesion between the optical adjustment layer and a transparent conductive layer described later can be improved.

  More specifically, this is because the material constituting the inorganic layer is scattered on the surface of the optical adjustment layer, that is, the silicon oxide particles are scattered as an image on the surface of the optical adjustment layer. The silicon oxide particles become nuclei, which are in close contact with the optical adjustment layer. At the same time, a substance that constitutes the transparent conductive layer described later grows around the nucleus, and the substance that grows from each nucleus eventually. By forming a film and eventually connecting them into a series of layers, the interlayer adhesion between the optical adjustment layer and the transparent conductive layer can be improved as a result.

  The preferred thickness of the inorganic layer in this embodiment is 2 nm or more and 10 nm or less, and the light refractive index is preferably 1.4 or more and 1.5 or less. By being within this range, the interlayer adhesion between the optical adjustment layer and the transparent conductive layer described later is suitably improved, and at the same time, coupled with the use of a low retardation type COP film as the base film, this embodiment The low retardation of the transparent conductive film according to the present invention can be obtained more suitably. Furthermore, by providing this inorganic layer, this acts as a base of a transparent conductive layer described later, and contributes to improving the durability of the transparent conductive layer.

Next, the transparent conductive layer laminated on the surface of the inorganic layer will be described.
As the transparent conductive layer, indium tin oxide (ITO), aluminum oxide, indium zinc oxide (IZO), or zinc oxide materials such as aluminum-added zinc oxide (AZO) or gallium-added zinc oxide (GZO) are used. It is possible. In this embodiment, crystallization type ITO is laminated.

  The method for laminating the transparent conductive layer may be a so-called dry coating method such as a conventionally known sputtering method, or may be a reactive film formation performed by introducing oxygen gas. Moreover, it is preferable that the thickness is 15 nm or more and 50 nm or less. If the film thickness is less than 15 nm, the required performance cannot be exhibited. If the film thickness is more than 50 nm, the transmittance is lowered, and the effect obtained for the cost is not high and is not efficient. The resistivity is preferably 50Ω / □ or more and 200Ω / □ or less. In this embodiment, the thickness is 35 nm and the resistivity is 70Ω / □.

As described above, the transparent conductive film according to the present embodiment is the second hard coat layer / (first easy adhesive layer) / base film / (second easy adhesive layer) / first hard coat layer / optical adjustment. Although it has a configuration of layer / inorganic layer / ITO layer, the actual use surface is light incident from the ITO layer side.

  Based on this assumption, the light refractive index of each layer is set to be high or low, that is, by combining so-called high refractive index layer and low refractive index layer, generation of fringes due to interference of light incident on each layer, and This suppresses the visibility of the electrode pattern caused by the above.

  Specifically, if the b * value of the light transmission hue of the transparent conductive film according to the present embodiment is 1.5 or less, the visibility of the electrode pattern can be suppressed.

(Embodiment 2)
Although it is the transparent conductive film according to the present embodiment obtained as described above, when this is actually used in the manufacturing process, it is important to be transparent by being exposed to an environment under high temperature and high pressure at the time of manufacturing. It can be seen that the conductive layer is damaged. Or, if it is attempted to transport without taking any special measures, the transparent conductive film may become defective due to scratches or cracks in the transparent conductive layer during the transport.

  Therefore, in the present embodiment, a transparent conductive film produced in a state in which a protective film protecting the surface of the transparent conductive film obtained in the first embodiment described above is attached in advance to the surface, This will be described as a second embodiment.

First, the transparent conductive film used as the object which sticks a protective film shall have the structure demonstrated in previous 1st Embodiment. That is, the second hard coat layer / (first easy adhesive layer) / base film / (second easy adhesive layer) / first hard coat layer / optical adjustment layer / inorganic layer / ITO layer.

  The protective film is attached to the surface opposite to the ITO layer in consideration of contamination of the ITO layer. That is, it sticks on the surface of a 2nd hard-coat layer.

  This protective film comprises a polymer resin film as a base material and an adhesive layer on the surface thereof. However, when the polymer resin film is originally provided with adhesiveness, the adhesive layer is necessary. do not do.

  Since each layer which comprises the transparent conductive film concerning 2nd Embodiment is the same as that of 1st Embodiment, the description is abbreviate | omitted here.

  In this embodiment, a protective film is attached to the surface of the second hard coat layer of the transparent conductive film having the same configuration as that described in the first embodiment, but the protective film is attached. When processing the transparent conductive film in such a state, it is necessary to give consideration so that the protective film does not have an adverse effect.

  This is because the protective film literally aims to protect the transparent conductive film, but more specifically, it is necessary when processing the transparent conductive film, that is, it can hold the stuck state. On the other hand, when the processing is finished, it must be easily peeled off from the transparent conductive film. Since it has been found that it is preferable to fit, it is within that range in the present embodiment.

  If the processing is taken into consideration, consideration must be given to the thermal contraction rate and thermal aberration. That is, if there is a large difference in the thermal shrinkage rate or thermal aberration between the transparent conductive film and the protective film adhered to the surface due to heating during processing, for example, the protective film can be used without permission during processing. This is because if it peels off or the protective film itself is damaged, the original purpose cannot be achieved.

  In order to satisfy the above conditions, in this embodiment, the adhesive strength is about 150 ° C. or slightly lower after 60 minutes at a peeling speed of 300 mm / min or more and 1000 mm / min or less and 200 N / 25 mm or less. Yes, the 150 ° C. heat shrinkage rate of the protective film and the 150 ° C. heat shrinkage rate of the ITO film were both 0.5% or less for both MD and TD. Under such conditions, as described above, the protective film can be beautifully peeled only when necessary.

  Furthermore, it is necessary to consider the curl in a state where the protective film is attached to the transparent conductive film. That is, it can be considered that the transparent conductive film curls due to the stress of the protective film itself, thereby causing a problem in the processing operation.

  By sticking the protective film described above to the transparent conductive film in advance, for example, it is possible to prevent the surface from being scratched when the transparent conductive film is being transported or to be processed at a high temperature. It becomes possible to prevent the transparent conductive layer from being damaged by the environment under high pressure.

  Although the first and second embodiments have been briefly described above, in either case, the first hard coat layer may be obtained by adding an inorganic filler to an ultraviolet curable resin. However, detailed description is omitted here.

  If it is the transparent conductive film according to the present invention described above, it is a transparent conductive film that realizes a lower retardation than the conventional one. For example, an organic display that is beginning to attract attention by using it for smartphones and the like recently. It becomes possible to obtain a very useful ITO film for the touch panel used.

Claims (5)

A second hard coat layer on one side of the substrate film;
At least on the surface opposite to the second hard coat layer lamination surface of the base film,
A first hard coat layer, an optical adjustment layer, an inorganic layer, a transparent conductive layer,
Is a transparent conductive film formed by laminating the layers in the order of description and in a state where each layer is in contact ,
The first hard coat layer is made of an ultraviolet curable resin,
The second hard coat layer is made of an ultraviolet curable resin,
The inorganic layer is made of silicon oxide and has a refractive index of 1.4 to 1.5.
The transparent conductive layer is a transparent conductive film that is a crystallized type indium tin oxide (ITO),
B * of the transmission hue of the light transmitted through the transparent conductive film is 1.5 or less,
The second hard coat layer is an ultraviolet curable resin to which an inorganic filler having an average major axis of 1.5 μm or more and 3.0 μm or less is added;
A transparent conductive film characterized by
The transparent conductive film according to claim 1,
The inorganic filler is any one of silicon oxide, zirconium oxide, titanium oxide, or niobium oxide;
A transparent conductive film characterized by The transparent conductive film according to claim 1 or 2,
The optical adjustment layer is an ultraviolet curable resin to which an inorganic filler is added,
A transparent conductive film characterized by The transparent conductive film according to any one of claims 1 to 3,
The base film is a cycloolefin film having a thickness of 20 μm or more and 100 μm or less,
The thicknesses of the first hard coat layer and the second hard coat layer are both 0.5 μm or more and 1.5 μm or less,
The thickness of the optical adjustment layer is 50 nm or more and 150 nm or less,
The inorganic layer is a layer made of silicon oxide having a thickness of 2 nm to 10 nm,
The transparent conductive layer has a thickness of 15 nm or more and 50 nm or less, and a resistance value of 50Ω / □ or more and 200Ω / □ or less,
A transparent conductive film characterized by The transparent conductive film according to any one of claims 1 to 4,
A protective film having an antistatic function is attached to the surface of the second hard coat layer;
A transparent conductive film characterized by