JP2016090963A - Color tone correction film, and transparent conductive film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film that suppresses coloring of transmitted light and has a high total ray transmittance, and to provide a color tone correction film for a base of the same.SOLUTION: A color tone correction film is formed by laminating a first color tone correction layer and a second color tone correction layer on one surface of a polyester film base material. A functional layer is, as necessary, laminated on the other surface of the polyester film base material. The first color tone correction layer contains titanium oxide fine particles and an active energy ray-curable resin, has a refractive index to light at a wavelength of 400 nm of 1.75-1.83, and has a film thickness of 32-70 nm. The second color tone correction layer has a refractive index to light at a wavelength of 400 nm of 1.33-1.53, and has a film thickness of 10-40 nm. A transparent conductive film is formed by laminating a tin-doped indium oxide layer having a refractive index to light at a wavelength of 400 nm of 1.85-2.35 and a film thickness of 5-50 nm, on the second color tone correction layer of the color tone correction film.SELECTED DRAWING: None

Description

  The present disclosure relates to a color correction film for a touch panel and a transparent conductive film in which a transparent conductive layer is laminated on the color correction film.

  Currently, touch panels are widely used as devices capable of inputting information by directly touching an image display unit. A touch panel has an input device that transmits light placed on a display screen such as a liquid crystal display device. As a typical form, a touch panel uses a change in capacitance that occurs between a transparent electrode and a finger. There is a touch panel.

  As a transparent conductive film for a touch panel, a transparent conductive film made of metal oxide such as indium oxide containing tin oxide (tin-doped indium oxide, ITO) or zinc oxide is laminated on a transparent base film. Commonly used. Such a transparent conductive film often has a yellow coloration at the same time that the total light transmittance is reduced due to a reduction in the transmittance in the short wavelength region of visible light derived from reflection and absorption in the transparent conductive layer. . For this reason, there is a problem that it is difficult to accurately express the color of the display device arranged under the touch panel.

  In order to solve this problem, Patent Document 1 proposes a transparent conductive film in which a transparent conductive layer is combined with a multilayer optical film. The transparent conductive film described in Patent Document 1 has a configuration in which a hard coat layer, a color tone correction layer 1, a color tone correction layer 2, and a tin-doped indium oxide layer are laminated on both sides of a transparent substrate film. The hard coat layer has a refractive index of 1.51 to 1.61 and a film thickness of 1 to 10 μm at a light wavelength of 400 nm. The color tone correction layer 1 includes metal oxide fine particles and an active energy ray-curable resin, and has a refractive index of 1.63-1.86 and a film thickness of 25-95 nm at a light wavelength of 400 nm. The color tone correction layer 2 includes silica fine particles and an active energy ray-curable resin, and has a refractive index of 1.33 to 1.53 and a film thickness of 10 to 55 nm at a light wavelength of 400 nm. The tin-doped indium oxide layer has a refractive index of 1.85 to 2.35 at a light wavelength of 400 nm and a film thickness of 5 to 50 nm. With such a configuration, an effect of reducing transmitted light coloring and a high transmittance are realized.

JP2013-99924A

  However, in the above-mentioned Patent Document 1, since a rigid hard coat layer is laminated on the side on which the tin-doped indium oxide layer is laminated on the transparent base film, the transparent conductive layer is applied to the transparent conductive layer due to stress caused by pressing during film handling. There was a problem that cracks occurred and the conductivity decreased.

  Therefore, the object of the present invention is to provide a transparent conductive film that suppresses coloring of transmitted light, has a high total light transmittance, and suppresses cracks during film handling, and a color tone correction film used as a base film thereof. Is to provide.

As means for that purpose, the present invention takes the following means.
(1) A color tone correction preliminary film in which a first color tone correction layer is laminated on one surface of a polyester film substrate, the first color tone correction layer comprising titanium oxide fine particles, an active energy ray-curable resin, A color correction preliminary film having a refractive index of 1.75 to 1.83 and a film thickness of 32 to 70 nm with respect to light having a wavelength of 400 nm.
(2) A second color tone correction layer is laminated on the first color tone correction layer of the color tone correction preliminary film according to (1), and the second color tone correction layer has a refractive index with respect to light having a wavelength of 400 nm. A color correction film having a thickness of 1.33 to 1.53 and a thickness of 10 to 40 nm.
(3) The color tone correction film according to (2), wherein the second color tone correction layer includes silica fine particles and an active energy ray-curable resin, and is formed by a wet film forming method.
(4) The color tone correction film according to (2), wherein the second color tone correction layer is made of silicon oxide and is formed by a dry film forming method.
(5) A tin-doped indium oxide layer is laminated on the second color tone correction layer of the color tone correction film according to any one of (2) to (4), and the tin-doped indium oxide layer is A transparent conductive film having a refractive index of 1.85 to 2.35 and a film thickness of 5 to 50 nm with respect to light having a wavelength of 400 nm.
(6) The color tone correction preliminary film according to (1), wherein a functional layer is laminated on the other surface of the polyester film substrate.
(7) The color correction film according to any one of (2) to (4), wherein a functional layer is laminated on the other surface of the polyester film substrate.
(8) The transparent conductive film according to (5), wherein a functional layer is laminated on the other surface of the polyester film substrate.
(9) The color correction preliminary film according to (6), wherein the functional layer is one or both of a hard coat layer and a transmittance improving layer.
(10) The color correction film according to (7), wherein the functional layer is one or both of a hard coat layer and a transmittance improving layer.
(11) The transparent conductive film according to (8), wherein the functional layer is one or both of a hard coat layer and a transmittance improving layer.

  In this specification, “XX to XX” indicating a numerical range means “XX or more and XX or less” unless otherwise specified.

  In the color tone correction film or transparent conductive film of the present invention, the first color tone correction layer, the second color tone correction layer, and the tin-doped indium oxide layer laminated on the polyester film substrate are made of materials, refractive index and film thickness for light having a wavelength of 400 nm. By setting appropriately, it is possible to suppress the coloring of transmitted light and to increase the total light transmittance while suppressing cracks.

It is a schematic diagram explaining the definition of the curvature after heat processing.

≪Color tone correction film≫
In the color tone correction film, a first color tone correction layer and a second color tone correction layer are laminated in this order on one surface of a polyester film substrate, and a functional layer is appropriately laminated on the other surface of the polyester film substrate. This color tone correction film can be used as a base film of a transparent conductive film as described later. Below, the component of this color tone correction film is demonstrated in order.

<Polyester film substrate>
A polyester film base material consists of a polyester film, for example, can use a polyethylene terephthalate (PET) resin. The thickness of the polyester film is preferably 25 to 400 μm, more preferably 25 to 188 μm. When the thickness of the polyester film is less than 25 μm or thicker than 400 μm, the handleability at the time of manufacturing and using the color tone correction film is unfavorable. The total light transmittance of the polyester film is preferably 88% or more. When it is less than 88%, the total light transmittance of the transparent conductive film is lowered, which is not preferable. The polyester film may contain various additives as long as the total light transmittance is not less than 88%. Examples of such additives include ultraviolet absorbers, antistatic agents, stabilizers, plasticizers, lubricants, flame retardants, and the like. In addition, the polyester film substrate has a known easy-adhesion layer having a refractive index of 1.50 to 1.80 in light having a wavelength of 400 nm in order to improve adhesion to the layer processed on the polyester film and reduce interference fringes. It may be provided.

<First color tone correction layer>
The first color tone correction layer is provided on the polyester film substrate, and can suppress coloring of the transparent color of the transparent conductive film by adjusting the refractive index and the film thickness within a predetermined range (details will be described later). it can. The first color tone correction layer includes titanium oxide fine particles and an active energy ray-curable resin. The first color tone correction layer is obtained by curing a coating solution for a first color tone correction layer containing titanium oxide fine particles, an active energy ray-curable resin, and a photopolymerization initiator with active energy rays (for example, ultraviolet rays and electron beams). It can be formed by a cured product.

  The active energy ray curable resin serves as a binder for the first color tone correction layer. As the active energy ray curable resin, one or more kinds selected from a monofunctional monomer and a polyfunctional monomer of (meth) acrylate are used. Specifically, (meth) acrylic acid alkyl ester, (meth) acrylic acid (poly) ethylene glycol group-containing (meth) acrylic acid ester and the like are preferable as the monofunctional monomer. Examples of the polyfunctional monomer include ester compounds of polyhydric alcohol and (meth) acrylic acid, polyfunctional polymerizable compounds containing two or more (meth) acryloyl groups such as urethane-modified acrylate, and the like. In the present specification, “(meth) acrylate” means acrylate or methacrylate. The same applies to “(meth) acrylic acid” and “(meth) acryloyl group”. The active energy ray-curable resin preferably has a refractive index of 1.4 to 1.7 with respect to light having a wavelength of 400 nm.

  The active energy ray-curable resin is preferably contained in the first color tone correction layer in an amount of 10 to 63 wt% (10 to 60 parts by weight in 100 parts by weight of the first color tone correction layer coating solution excluding the solvent). When the content of the active energy ray-curable resin is less than 10 wt%, the relative amount of the active energy ray-curable resin with respect to the coating film is small and the coating film becomes brittle. On the other hand, if the content of the active energy ray-curable resin exceeds 63 wt%, the refractive index of the first color tone correction layer is outside the predetermined range, which is not preferable.

  The titanium oxide fine particles are preferably blended to adjust the refractive index of the first color tone correction layer. The refractive index of titanium oxide with respect to light having a wavelength of 400 nm is 2.2 to 3.0, although it varies depending on the production method.

  Titanium oxide fine particles are contained in the first color tone correction layer in an amount of 35 to 85 wt% (35 to 85 parts by weight in 100 parts by weight of the first color tone correction layer coating solution excluding the solvent). If the content of the titanium oxide fine particles is less than 35 wt%, the refractive index of the first color tone correction layer is outside the predetermined range, which is not preferable. On the other hand, when the content of the titanium oxide fine particles exceeds 85 wt%, the relative amount of the titanium oxide fine particles with respect to the coating film increases, and the coating film becomes brittle.

  The photopolymerization initiator is used as a polymerization initiator when the first color tone correction layer coating liquid is cured by an active energy ray such as ultraviolet (UV) to form a coating film. The photopolymerization initiator is not particularly limited as long as it initiates polymerization upon irradiation with active energy rays, and known compounds can be used. For example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 -One, acetophenone polymerization initiators such as 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one, benzoin, 2,2-dimethoxy 1,2 -Benzoin polymerization initiators such as diphenylethane-1-one, benzophenone, [4- (methylphenylthio) phenyl] phenylmethanone, 4-hydroxybenzophenone, 4-phenylbenzophenone, 3,3 ', 4,4' -Benzophenone polymerization initiators such as tetra (t-butylperoxycarbonyl) benzophenone, 2-chlorothio Xanthone, such thioxanthone type polymerization initiators such as 2,4-diethyl thioxanthone, and the like.

  The photopolymerization initiator is preferably contained in 1 to 10 parts by weight in 100 parts by weight of the first color tone correction layer coating solution excluding the solvent. When the content of the photopolymerization initiator is less than 1 part by weight, the active energy ray curable resin is not sufficiently cured. On the other hand, if the content of the photopolymerization initiator exceeds 10 parts by weight, the photopolymerization initiator is unnecessarily increased, which is not preferable.

  The coating solution for the first color tone correction layer may contain other additives so long as the refractive index does not deviate from the range described later. Examples of other additives include fluorine-based and silicon-based leveling agents, anti-blocking agents such as silica fine particles and acrylic fine particles.

  The solvent of the coating solution for the first color tone correction layer is not particularly limited as long as it is a known one that has been conventionally used for the coating solution for forming each layer in this type of color tone correction film. An ester solvent can be selected in a timely manner.

The first color tone correction layer is formed so that the refractive index with respect to light having a wavelength of 400 nm is 1.75 to 1.83 by including the titanium oxide fine particles and the active energy ray-curable resin in the above ranges. When the refractive index of the first color tone correction layer is outside this range, the total light transmittance becomes low, or the value of b ^* of the transmitted color in the L ^* a ^* b ^* color system defined in JIS Z 8729. Becomes larger, and the yellow color of the transparent color of the transparent conductive film is clearly recognized. The film thickness of the first color tone correction layer needs to be 32 to 70 nm. If the film thickness of the first color tone correction layer is outside this range, the total light transmittance will be low, or the value of b ^* will be large, and the transparent yellow color of the transparent conductive film will be clear. Be recognized.

  The first color tone correction layer is formed by applying a coating solution for the first color tone correction layer to the polyester film base material and then curing it by irradiation with active energy rays. The application method of the coating solution for the first color tone correction layer is not particularly limited. For example, roll coating method, spin coating method, dip coating method, spray coating method, bar coating method, knife coating method, die coating method, ink jet method, gravure coating A known wet coating method such as a method can be employed. The type of active energy ray is not particularly limited, but it is preferable to use ultraviolet rays from the viewpoint of convenience and the like. In addition, in order to improve the adhesiveness of a 1st color tone correction layer, it is also possible to give pretreatments, such as a corona discharge process, to the surface of a polyester film base material previously.

<Second color tone correction layer>
The second color tone correction layer is provided on the first color tone correction layer, and corrects the color tone of the transparent conductive film by adjusting the refractive index and the film thickness within a predetermined range (details will be described later) (transparent coloration). It is a layer that suppresses).

  The second color tone correction layer is formed by a wet film forming method in which a coating solution for the second color tone correction layer containing silica fine particles and an active energy ray-curable resin is cured with active energy rays (for example, ultraviolet rays and electron beams). be able to.

  Silica fine particles are blended in order to actively lower the refractive index. As such silica fine particles, colloidal silica and hollow silica fine particles are preferable. The refractive indexes of colloidal silica and hollow silica fine particles with respect to light having a wavelength of 400 nm differ depending on the production method, but are preferably 1.23-1.50. The silica fine particles are preferably contained in the second color tone correction layer in an amount of 20 to 90 wt% (20 to 85 parts by weight in 100 parts by weight of the second color tone correction layer coating solution excluding the solvent). When the content of the silica fine particles is less than 20 wt%, the refractive index of the second color tone correction layer cannot be in a predetermined range (details will be described later). On the other hand, when the content of silica fine particles is more than 90 wt%, the coating film strength becomes weak.

  The active energy ray-curable resin used as the binder preferably has a refractive index of 1.40 to 1.70 with respect to light having a wavelength of 400 nm. As the active energy ray-curable resin, the same type as the active energy ray-curable resin used in the first color tone correction layer can be used. The content of the active energy ray-curable resin in the second color tone correction layer is about 10 to 79 wt% (10 to 75 parts by weight in 100 parts by weight of the second color tone correction layer coating solution excluding the solvent). Here, the surface of the silica fine particles may be modified with a silane coupling agent having a (meth) acryloyl group. By modifying the surface of the silica fine particles with a silane coupling agent having a (meth) acryloyl group or the like, a covalent bond with the active energy ray-curable resin is generated, and a tendency that the coating film strength is increased is observed.

  The coating solution for the second color tone correction layer also contains a photopolymerization initiator. The photopolymerization initiator may be the same type as the photopolymerization initiator used in the first color tone correction layer coating solution. The photopolymerization initiator is preferably contained in 1 to 10 parts by weight in 100 parts by weight of the second color tone correction layer coating solution excluding the solvent. If the content of the photopolymerization initiator in the coating solution for the second color tone correction layer is less than 1 part by weight, the active energy ray-curable resin is not sufficiently cured, and if it exceeds 10 parts by weight, it is undesirably increased.

  The coating solution for the second color tone correction layer may contain other additives as long as the refractive index does not deviate from the range described later. Other additives include surface conditioners, antifouling agents, slip agents and the like.

The second color tone correction layer is formed by blending the silica fine particles and the active energy ray-curable resin such that the refractive index with respect to light having a wavelength of 400 nm is 1.33 to 1.53. When the refractive index of the second color tone correction layer is outside this range, the total light transmittance becomes low, or the value of b ^* of the transmitted color in the L ^* a ^* b ^* color system defined in JIS Z 8729. Becomes larger, and the yellow color of the transparent color of the transparent conductive film is clearly recognized. The film thickness of the second color tone correction layer needs to be 10 to 40 nm. If the film thickness of the second color tone correction layer is outside this range, the total light transmittance will be low, or the value of b ^* will be large, and the transparent yellow color of the transparent conductive film will be clear. Be recognized.

  The second color tone correction layer is formed by applying the second color tone correction layer coating liquid on the formed first color tone correction layer and then curing it by irradiation with active energy rays. The application method of the coating solution for the second color tone correction layer is not particularly limited. For example, roll coating method, spin coating method, dip coating method, spray coating method, bar coating method, knife coating method, die coating method, ink jet method, gravure coating A known wet coating method such as a method can be employed. The type of active energy ray is not particularly limited, but it is preferable to use ultraviolet rays from the viewpoint of convenience and the like.

Further, the second color tone correction layer may be formed on the formed first color tone correction layer by a dry film forming method using silicon oxide (refractive index for light having a wavelength of 400 nm: 1.47) which is an inorganic substance. I can do it. The film thickness formed by dry film formation needs to be 10 to 40 nm, as in the case of wet film formation. When the film thickness is outside this range, the value of b ^* becomes large, and the yellowish coloring of the transparent color of the transparent conductive film is clearly recognized. As a dry film forming method, a known film forming method such as a vacuum deposition method, a sputtering method, an ion spraying method, a CVD method, or the like can be employed.

<Functional layer>
If necessary, a functional layer can be provided on the other surface opposite to the one surface on which the first color tone correction layer of the polyester film substrate is laminated. As this functional layer, any functional layer that can impart a predetermined function to the transparent conductive film can be applied. Typical examples of the functional layer include a hard coat layer and a transmittance improving layer, but other examples include an ultraviolet absorbing layer, an antistatic layer, and an antiblocking layer. In other words, the hard coat function that increases hardness, the transmittance improvement function that improves the transmittance, the ultraviolet absorption function that absorbs ultraviolet rays, the antistatic function that suppresses the accumulation of static electricity, and the adhesion between films. Examples thereof include an anti-blocking function to suppress. The functional layer has these functions singly or in combination. Only one functional layer may be provided, or a plurality of functional layers may be provided.

  A hard-coat layer is a layer which improves the hardness and scratch resistance of the film surface by providing on a polyester film base material. As long as the surface hardness and scratch resistance can be improved, all known resins used for the hard coat layer in this type of film can be used.

  As resin used for a hard-coat layer, the same kind as active energy ray hardening-type resin used with a 1st color tone correction layer can be used. The hard coat layer can be formed of a cured product obtained by curing a hard coat layer coating liquid containing an active energy ray-curable resin and a photopolymerization initiator with active energy rays (for example, ultraviolet rays and electron beams). The photopolymerization initiator may be the same as the photopolymerization initiator used in the first color tone correction layer coating solution.

  The solvent of the coating solution is not particularly limited as long as it is a known one that has been conventionally used for the coating solution for forming each layer in this kind of color tone correction film. For example, alcohol-based, ketone-based, and ester-based solvents may be used. Can be selected in a timely manner.

  The hard coat layer may contain translucent fine particles. The light-transmitting fine particles form irregularities on the surface of the hard coat layer and improve the winding property in the manufacturing process. Arbitrary materials can be used for the translucent fine particles. Examples of such translucent fine particles include silica, a polymer obtained by polymerizing at least one monomer selected from vinyl chloride, (meth) acrylic monomer, styrene, and ethylene. It is formed.

  Furthermore, the hard coat layer may contain metal oxide fine particles for adjusting the refractive index. Examples of the metal oxide include ITO (indium-tin composite oxide, refractive index 2.0), ATO (antimony-tin composite oxide, refractive index 2.1), antimony oxide (refractive index 2.1), and oxidation. At least one selected from the group consisting of zinc (refractive index 2.1), zirconium oxide (refractive index 2.1), and titanium oxide (refractive index 2.4) is preferable.

  Furthermore, the hard coat layer may contain other additives. Examples of other additives include surface conditioners and slip agents.

  The hard coat layer preferably has a refractive index of 1.49 to 1.68 for light having a wavelength of 589 nm. When the refractive index is out of the above range, the difference in refractive index between the polyester film substrate and the hard coat layer becomes large and interference jima occurs, which is not preferable. Moreover, it is preferable that the film thickness of a hard-coat layer is 0.4-3.5 micrometers. When the film thickness is thinner than 0.4 μm, the pencil hardness is less than H, which is not preferable. When the film thickness is thicker than 3.5 μm, curling due to curing shrinkage becomes strong and becomes unnecessarily thick, which is not preferable because productivity and workability are lowered.

  The transmittance improving layer is provided on the polyester film base material or the hard coat layer laminated on the polyester film base material, and the transmittance is reduced by reducing the reflection depending on the relative relationship with the polyester film base material or the hard coat layer. It is a layer that improves The transmittance improving layer is made of a cured product obtained by curing a coating solution for a transmittance improving layer obtained by mixing silica fine particles and an active energy ray-curable resin with active energy rays (for example, ultraviolet rays or electron beams).

  The silica fine particles are blended to actively reduce the refractive index of the transmittance improving layer. The silica fine particles may be the same type as the silica fine particles used in the second color tone correction layer. The silica fine particles are preferably contained in the transmittance improving layer in an amount of 20 to 90 wt% (20 to 85 parts by weight in 100 parts by weight of the coating solution for the transmittance improving layer excluding the solvent). When the content of the silica fine particles is less than 20 wt%, the refractive index of the transmittance improving layer cannot be in a predetermined range (details will be described later). On the other hand, when the content of the silica fine particles is more than 90 wt%, the coating film strength becomes weak.

  The active energy ray-curable resin used as the binder preferably has a refractive index of 1.38 to 1.67 with respect to light having a wavelength of 589 nm. As the active energy ray-curable resin, the same type as the active energy ray-curable resin used in the transmittance improving layer can be used. The content of the active energy ray-curable resin in the transmittance improving layer is about 10 to 79 wt% (10 to 75 parts by weight in 100 parts by weight of the coating solution for the transmittance improving layer excluding the solvent). Here, the surface of the silica fine particles may be modified with a silane coupling agent having a (meth) acryloyl group. By modifying the surface of the silica fine particles with a silane coupling agent having a (meth) acryloyl group or the like, a covalent bond with the active energy ray-curable resin is generated, and a tendency that the coating film strength is increased is observed.

  Further, the transmittance improving layer coating solution also contains a photopolymerization initiator. The photopolymerization initiator may be the same type as the photopolymerization initiator used in the first color tone correction layer coating solution. It is preferable that 1-10 weight part of photoinitiators are contained in 100 weight part of coating liquid for transmittance | permeability improvement layers except a solvent. If the content of the photopolymerization initiator in the coating solution for the transmittance improving layer is less than 1 part by weight, the curing of the active energy ray-curable resin is insufficient, and if it exceeds 10 parts by weight, it is undesirably increased.

  The coating liquid for transmittance improving layer may contain other additives as long as the refractive index does not deviate from the range described later. Other additives include surface conditioners, antifouling agents, slip agents and the like.

The transmittance improving layer is formed by blending silica fine particles and an active energy ray-curable resin so that the refractive index with respect to light having a wavelength of 589 nm is 1.31 to 1.51. When the refractive index of the transmittance improving layer is less than 1.31, the ratio of particles in the coating film increases and the haze value increases, so that the total light transmittance decreases. On the other hand, when the refractive index of the transmittance improving layer is larger than 1.51, the total light transmittance is lowered because the reflection reducing function is lowered. The value of b ^* of the transmitted color in the L ^* a ^* b ^* color system specified in JIS Z 8729 becomes large, and the yellowness of the transmitted color of the transparent conductive film is clearly recognized. . Moreover, it is preferable that the film thickness after drying hardening of the transmittance | permeability improvement layer is 60-100 nm. When the film thickness of the transmittance improving layer is less than 60 nm, the total light transmittance is lowered because the reflection reducing function is lowered. Moreover, when the film thickness of the transmittance improving layer is thicker than 100 nm, the value of b ^* increases, and the yellowish coloring of the transparent color of the transparent conductive film is clearly recognized.

  The color tone correction film is basically manufactured by laminating a first color tone correction layer, a second color tone correction layer, and an appropriate functional layer on a polyester film substrate. In some cases, the first color tone correction layer alone is circulated as a color tone correction preliminary film, and then the remaining layers are laminated.

≪Transparent conductive film≫
The transparent conductive film has a tin-doped indium oxide layer on the second color correction layer of the color correction film. The color of transmitted light of the transparent conductive film can be evaluated by b ^* in the Lab color system defined in JIS Z 8729, and preferably -1 ≦ b ^* ≦ 1. In the case of b ^* > 1, the transparent conductive film appears to be colored yellow, which is not preferable. On the other hand, when b ^* <-1, the transparent conductive film appears to be colored blue, which is not preferable.

  The total light transmittance of the transparent conductive film is preferably 89.0% or more. When the total light transmittance is less than 89.0%, the visibility deteriorates, which is not preferable.

<Tin-doped indium oxide layer>
The tin-doped indium oxide layer (ITO layer) is a transparent conductive layer, and has a refractive index of 1.85 to 2.35 and a film thickness of 5 to 50 nm with respect to light having a wavelength of 400 nm. If the refractive index is out of this range, the optical interference with other layers such as the second color tone correction layer does not work properly, so that the transparent conductive film is colored and the total light transmittance is also reduced. . When the thickness of the ITO layer is less than 5 nm, it is difficult to form the ITO layer to a uniform thickness, and a stable resistance cannot be obtained, which is not preferable. In addition, when the thickness of the ITO layer is greater than 50 nm, the absorption of light by the ITO layer itself is strong, and the effect of reducing the coloring of the transmitted color is diminished, and the total light transmittance tends to be small.

<Formation of tin-doped indium oxide layer>
The method for forming the tin-doped indium oxide layer is not particularly limited, and for example, a vapor deposition method, a sputtering method, an ion plating method, and a CVD method can be employed. Among these, the vapor deposition method and the sputtering method are particularly preferable from the viewpoint of controlling the layer thickness. In addition, after forming a tin dope indium oxide layer, it anneals within the range of 100 to 200 degreeC, and crystallizes. Specifically, when crystallization is performed at a high temperature, the refractive index of the tin-doped indium oxide layer tends to decrease. Accordingly, the refractive index of the tin-doped indium oxide layer can be adjusted by controlling the annealing temperature and time.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the scope of these examples. Further, the refractive index, transmitted color, total light transmittance, warpage after heat treatment, and crack resistance in each example were measured by the following methods.

<Refractive index (first color tone correction layer, second color tone correction layer, hard coat layer, transmittance improving layer)>
(1) A coating solution for each layer is formed on a PET film (trade name “A4100”, manufactured by Toyobo Co., Ltd.) having a refractive index of 1.72 with respect to light having a wavelength of 400 nm by a dip coater (produced by Sugiyama Motochemical Co., Ltd.). Each of the films was applied by adjusting the thickness of the layer so that the film thickness after drying and curing was about 100 to 500 nm.
(2) After drying, a sample for refractive index measurement was prepared by irradiating with an ultraviolet ray of 400 mJ using a 120 W high pressure mercury lamp in a nitrogen atmosphere by an ultraviolet irradiation device (manufactured by Iwasaki Electric Co., Ltd.) and curing. The back surface of the cured PET film was roughened with sandpaper, and the reflection spectrum was measured with a reflection spectral film thickness meter (“FE-3000”, manufactured by Otsuka Electronics Co., Ltd.).
(3) From the reflectance read from the reflection spectrum, the constant of the n-Cauchy wavelength dispersion formula (Equation 1) shown below was determined to determine the refractive index.
N (λ) = a / λ ⁴ + b / λ ² + c (Formula 1)
(N: refractive index, λ: wavelength, a, b, c: chromatic dispersion constant)

<Refractive index (ITO layer)>
(1) Sputtering was performed on a PET film (trade name “A4100” manufactured by Toyobo Co., Ltd.) having a refractive index with respect to light having a wavelength of 400 nm using an ITO target of indium: tin = 10: 1. A tin-doped indium oxide layer (ITO layer) as a transparent conductive layer having a thickness of 20 nm was formed and annealed under the conditions of the following examples and comparative examples to prepare a sample for measuring the refractive index of a transparent conductive film. .
(2) The reflection spectrum was measured with a reflection spectral film thickness meter (“FE-3000”, manufactured by Otsuka Electronics Co., Ltd.) after roughening the back surface of the transparent conductive film with sandpaper and painting with a black paint.
(3) From the reflectance read from the reflection spectrum, the refractive index at a wavelength of 400 nm of light was obtained using the above (Equation 1).

  In addition, the refractive index of each layer described in each table (described later) is a refractive index obtained from the sample for refractive index measurement.

<Transparent color>
Using a color difference meter (“SQ-2000”, manufactured by Nippon Denshoku Industries Co., Ltd.), the transmitted color, b ^* , of the transparent conductive film was measured. This b ^* is a value in the L ^* a ^* b ^* color system defined in JIS Z 8729.

<Total light transmittance>
The total light transmittance (%) of the transparent conductive film was measured with a haze meter (“NDH2000”, manufactured by Nippon Denshoku Industries Co., Ltd.).

<Warpage after heat treatment>
A transparent conductive film cut to a length of 50 mm and a width of 100 mm is left in a thermostatic bath at 150 ° C. for 1 hour to perform heat treatment. After that, as shown in FIG. 1, the transparent conductive film is placed on the flat surface with the ITO layer facing upward, and the amount of warping at the four corners (1), (2), (3) and (4) is measured. Measure the average value (warp average value). The average value of warpage was determined to be less than 10 mm, and the average value of warpage was determined to be 10 mm or more.

<Evaluation of crack resistance>
Place the transparent conductive film on the flat surface with the ITO layer on top, place an iron ball with a diameter of 1 mm on it, apply a load of 100 g from the top of the iron ball, and confirm that the transparent conductive film is cracked visually. To do. The case where there was no crack was judged as ◯, and the case where there was a crack was judged as x.

(Preparation of first color correction layer)
The following raw materials were used as the first color tone correction layer coating liquid, and the respective raw materials were mixed in the composition described in Table 1 below to prepare first color tone correction layer coating liquids B-1 to B-6. The refractive index of the 1st color tone correction layer formed using the obtained coating liquids B-1 to B-6 for the 1st color tone correction layer was measured. The results are also shown in Table 1.

  As the metal oxide fine particles, a titanium oxide fine particle dispersion (CIRM Kasei Co., Ltd. ZRMEK25% -F47) or a zirconium oxide fine particle dispersion (Cii Kasei Co., Ltd. RTTMIBK15WT% -N24) was used. In addition, hexafunctional urethane acrylate (purple UV-7600B manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used as the active energy ray curable resin. The metal oxide fine particles and the active energy ray curable resin, the photopolymerization initiator, and the solvent were mixed at a weight ratio of 95: 5: 1000. IRGACURE184 (I-184) manufactured by Ciba Specialty Chemicals Co., Ltd. was used as a photopolymerization initiator. Further, methyl isobutyl ketone was used as a solvent.

[Preparation of coating solution for second color tone correction layer]
The following raw materials were used as the second color tone correction layer coating liquid, and the respective raw materials were mixed in the composition described in Table 2 below to prepare second color tone correction layer coating liquids C-1 to C-5. The refractive index of the second color tone correction layer formed using the obtained second color tone correction layer coating liquids C-1 to C-5 was measured. The results are shown in Table 2.

  As silica fine particles, “PL-1” manufactured by Fuso Chemical Industry Co., Ltd. or acrylic modified hollow silica fine particles “Thruria NAU” manufactured by JGC Catalysts & Chemicals Co., Ltd. were used. Further, a zirconium oxide fine particle dispersion (ZRMEK 25% -F47, manufactured by CI Kasei Co., Ltd.) was used as the metal oxide fine particles. Further, dipentaerythritol hexaacrylate (DPHA manufactured by Nippon Kayaku Co., Ltd.) was used as the active energy ray curable resin. IRGACURE907 (I-907) manufactured by Ciba Specialty Chemicals Co., Ltd. was used as a photopolymerization initiator. Isopropyl alcohol was used as a solvent. The fine particle component (silica fine particles or metal oxide fine particles), the active energy ray-curable resin, the photopolymerization initiator, and the solvent were mixed at a weight ratio of 95: 5: 4000.

[Preparation of coating liquid for hard coat layer]
The following raw materials were used as the hard coat layer coating liquid, and the respective raw materials were mixed in the composition described in Table 3 below to prepare hard coat layer coating liquids D-1 to D-2. The refractive index with respect to the wavelength of 589 nm of the light of the hard coat layer formed using the obtained coating liquids D-1 to D-2 for hard coat layer was measured. The results are also shown in Table 3.

As organic fine particles, acrylic organic fine particles (MX-80H3wT manufactured by Soken Chemical Co., Ltd.) were used. As the metal oxide fine particles, a zirconium oxide fine particle dispersion (ZRMEK 25% -F47, manufactured by CI Kasei Co., Ltd.) was used. In addition, hexafunctional urethane acrylate (purple UV-7600B manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used as the active energy ray curable resin. Organic fine particles or metal oxide fine particles and an active energy ray-curable resin, a photopolymerization initiator, and a solvent were mixed at a weight ratio of 95: 5: 100. IRGACURE184 (I-184) manufactured by Ciba Specialty Chemicals Co., Ltd. was used as a photopolymerization initiator. Further, methyl isobutyl ketone was used as a solvent.

(Preparation of coating solution for transmittance improving layer)
The following raw materials are used as the coating liquid for the transmittance improving layer, and each raw material has the composition described in Table 4 below, and the fine particle component (silica fine particles or metal oxide fine particles) and the active energy ray-curable resin, and photopolymerization start. The agent and the solvent were mixed at a weight ratio of 95: 5: 4000 to prepare transmittance improving layer coating liquids E-1 to E-2. The refractive index with respect to the wavelength 589 nm of the light of the transmittance improving layer formed using the obtained coating liquids E-1 to E-2 for the transmittance improving layer was measured. The results are shown in Table 4.

  As silica fine particles, “PL-1” manufactured by Fuso Chemical Industry Co., Ltd. or acrylic modified hollow silica fine particles “Thruria NAU” manufactured by JGC Catalysts & Chemicals Co., Ltd. were used. Further, dipentaerythritol hexaacrylate (DPHA manufactured by Nippon Kayaku Co., Ltd.) was used as the active energy ray curable resin. IRGACURE907 (I-907) manufactured by Ciba Specialty Chemicals Co., Ltd. was used as a photopolymerization initiator. Isopropyl alcohol was used as a solvent.

(Example 1-1)
By coating the first color tone correction layer coating liquid (B-1) on one side of a transparent PET film with a thickness of 50 μm with a bar coater, and irradiating it with 400 mJ ultraviolet rays with a 120 W high-pressure mercury lamp and curing it. A first color correction layer was formed. Further, the color tone correction is carried out by applying the coating solution (C-1) for the second color tone correction layer on the first color tone correction layer with a bar coater and irradiating with 400 mJ ultraviolet rays with a 120 W high pressure mercury lamp. A film was prepared (see Table 5 below).

(Example 1-2)
The hard coat layer coating liquid (D-1) was applied to the other side (the opposite side of the first color tone correction layer) of the PET film of the color tone correction film produced in Example 1-1 with a bar coater. A hard coat layer was formed by irradiating and curing ultraviolet rays of 400 mJ with a high-pressure mercury lamp to produce a color tone correction film (see Table 5 below).

(Example 1-3 to Example 1-10)
A color tone correction film was produced in the same manner as Example 1-2 except that the first color tone correction layer and the second color tone correction layer were made of the materials and film thicknesses shown in Table 5 below (see Table 5 below). .

(Example 1-11)
The transmittance improving layer coating liquid (E-1) was applied to the other side (the opposite side of the first color tone correction layer) of the PET film of the color tone correction film prepared in Example 1-1 with a bar coater, A transmittance improving layer was formed by irradiating and curing an ultraviolet ray of 400 mJ with a 120 W high-pressure mercury lamp, and a color tone correction film was produced (see Table 5 below).

(Example 1-12)
The transmittance improving layer coating liquid (E-2) was applied to the other surface (opposite surface of the first color correction layer) of the PET film of the color correction film produced in Example 1-1 with a bar coater, A transmittance improving layer was formed by irradiating and curing an ultraviolet ray of 400 mJ with a 120 W high-pressure mercury lamp, and a color tone correction film was produced (see Table 5 below).

(Example 1-13)
The hard coat layer coating liquid (D-1) was applied to the other side (the opposite side of the first color tone correction layer) of the PET film of the color tone correction film produced in Example 1-1 with a bar coater. A hard coat layer was formed by curing by irradiating 400 mJ ultraviolet rays with a high-pressure mercury lamp. Subsequently, a transmittance improving layer coating solution (E-1) is applied onto the hard coat layer with a bar coater, and cured by irradiating with 400 mJ ultraviolet rays with a 120 W high pressure mercury lamp. To prepare a color tone correction film (see Table 5 below).

(Example 1-14)
The hard coat layer coating liquid (D-1) was applied to the other side (the opposite side of the first color tone correction layer) of the PET film of the color tone correction film produced in Example 1-1 with a bar coater. A hard coat layer was formed by curing by irradiating 400 mJ ultraviolet rays with a high-pressure mercury lamp. Subsequently, the transmittance improving layer coating solution (E-2) is applied on the hard coat layer with a bar coater, and cured by irradiating with 400 mJ ultraviolet rays with a 120 W high pressure mercury lamp. To prepare a color tone correction film (see Table 5 below).

(Example 1-15)
The hard coat layer coating liquid (D-2) was applied to the other side of the PET film of the color tone correction film produced in Example 1-1 (the opposite side of the first color tone correction layer) with a bar coater, and 120 W A hard coat layer was formed by curing by irradiating 400 mJ ultraviolet rays with a high-pressure mercury lamp. Subsequently, a transmittance improving layer coating solution (E-1) is applied onto the hard coat layer with a bar coater, and cured by irradiating with 400 mJ ultraviolet rays with a 120 W high pressure mercury lamp. To prepare a color tone correction film (see Table 5 below).

(Example 1-16)
The hard coat layer coating liquid (D-2) was applied to the other side of the PET film of the color tone correction film produced in Example 1-1 (the opposite side of the first color tone correction layer) with a bar coater, and 120 W A hard coat layer was formed by curing by irradiating 400 mJ ultraviolet rays with a high-pressure mercury lamp. Subsequently, the transmittance improving layer coating solution (E-2) is applied on the hard coat layer with a bar coater, and cured by irradiating with 400 mJ ultraviolet rays with a 120 W high pressure mercury lamp. To prepare a color tone correction film (see Table 5 below).

(Example 2-1)
By coating the first color tone correction layer coating liquid (B-1) on one side of a transparent PET film with a thickness of 50 μm with a bar coater, and irradiating it with 400 mJ ultraviolet rays with a 120 W high-pressure mercury lamp and curing it. A first color correction layer was formed. Subsequently, a second color tone correction layer was formed on the first color tone correction layer by vacuum deposition of SiO ₂ . Further, the hard coat layer coating liquid (D-1) was applied to the other side of the PET film (opposite side of the first color tone correction layer) with a bar coater, and irradiated with 400 mJ ultraviolet rays with a 120 W high-pressure mercury lamp. A hard coat layer was formed by curing to produce a color correction film (see Table 6 below).

(Example 2-2)
By coating the first color tone correction layer coating liquid (B-1) on one side of a transparent PET film with a thickness of 50 μm with a bar coater, and irradiating it with 400 mJ ultraviolet rays with a 120 W high-pressure mercury lamp and curing it. A first color correction layer was formed. Subsequently, a second color tone correction layer was formed on the first color tone correction layer by vacuum deposition of SiO ₂ . Further, the transmittance improving layer coating liquid (E-1) was applied to the other side of the PET film (opposite side of the first color tone correction layer) with a bar coater, and irradiated with 400 mJ of ultraviolet light with a 120 W high pressure mercury lamp. Then, a transmittance improving layer was formed by curing, and a color tone correction film was produced (see Table 6 below).

(Example 2-3)
By coating the first color tone correction layer coating liquid (B-1) on one side of a transparent PET film with a thickness of 50 μm with a bar coater, and irradiating it with 400 mJ ultraviolet rays with a 120 W high-pressure mercury lamp and curing it. A first color correction layer was formed. Subsequently, a second color tone correction layer was formed on the first color tone correction layer by vacuum deposition of SiO ₂ . Further, the hard coat layer coating liquid (D-2) was applied to the other side of the PET film (opposite side of the first color correction layer) with a bar coater, and irradiated with 400 mJ of ultraviolet light with a 120 W high-pressure mercury lamp. A hard coat layer was formed by curing. Subsequently, a transmittance improving layer coating solution (E-1) is applied onto the hard coat layer with a bar coater, and cured by irradiating with 400 mJ ultraviolet rays with a 120 W high pressure mercury lamp. To prepare a color tone correction film (see Table 6 below).

(Example 3-1)
Sputtering is performed on the second color correction layer of the color correction film of Example 1-1 using an ITO target of indium: tin = 10: 1, thereby forming a tin-doped indium oxide layer (ITO layer having a thickness of 25 nm). ) And an annealing treatment at 150 ° C. for 30 minutes to produce a transparent conductive film. With respect to the obtained transparent conductive film, the transmission color b ^* , the total light transmittance, the warp after heat treatment, and the crack resistance were measured by the above methods. The results are shown in Table 7 below.

(Example 3-2 to Example 3-13, Example 3-19 to Example 3-21)
A transparent conductive film was produced in the same manner as in Example 3-1 except that the color tone correction film shown in Table 5 was used (see Table 7 below).

(Example 3-17)
On the second color correction layer of the color correction film of Example 1-2, sputtering was performed using an ITO target of indium: tin = 10: 1, thereby forming a tin-doped indium oxide layer (ITO layer having a thickness of 40 nm). And annealed at 150 ° C. for 100 minutes to produce a transparent conductive film (see Table 7 below).

(Example 3-18)
On the second color correction layer of the color correction film of Example 1-2, by sputtering using an ITO target of indium: tin = 10: 1, a tin-doped indium oxide layer (ITO layer having a thickness of 20 nm) ) And annealed at 120 ° C. for 60 minutes to produce a transparent conductive film (see Table 7 below).

(Comparative Example 1-1, Comparative Example 1-3, Comparative Example 1-10)
A color tone correction film was produced in the same manner as Example 1-2 except that the first color tone correction layer and the second color tone correction layer were made of the materials and film thicknesses shown in Table 8 below (see Table 8 below). .
(Comparative Example 1-2)
A hard coat layer was formed on one surface of the PET film by irradiating and curing 400 mJ of ultraviolet light with a coating liquid for hard coat layer (D-1) and a 120 W high pressure mercury lamp. Further, the first color tone correction layer coating liquid (B-1) is applied on the hard coat layer with a bar coater and cured by irradiating with 400 mJ ultraviolet rays with a 120 W high pressure mercury lamp. A layer was formed. Further, the color tone correction is carried out by applying the coating solution (C-1) for the second color tone correction layer on the first color tone correction layer with a bar coater and irradiating with 400 mJ ultraviolet rays with a 120 W high pressure mercury lamp. A film was prepared (see Table 8 below).

(Comparative Example 2-1 to Comparative Example 2-10)
A transparent conductive film was produced in the same manner as in Example 3-1, except that the color tone correction film shown in Table 9 was used. With respect to the obtained transparent conductive film, the transmission color b ^* , the total light transmittance, the warp after heat treatment, and the crack resistance were measured by the above methods. The results are shown in Table 9 below.

(Comparative Example 2-11)
On the second color correction layer of the color correction film of Example 1-2, sputtering was performed using an ITO target of indium: tin = 10: 1, thereby forming a tin-doped indium oxide layer (ITO layer having a thickness of 70 nm). ) And annealed at 100 ° C. for 60 minutes to produce a transparent conductive film (see Table 9 below).

(Comparative Example 2-12)
On the second color correction layer of the color correction film of Example 1-2, by sputtering using an ITO target of indium: tin = 10: 1, a tin-doped indium oxide layer (ITO layer having a thickness of 20 nm) ) And annealed at 150 ° C. for 30 minutes to produce a transparent conductive film (see Table 9 below).

(Results and Discussion)
In Examples 3-1 to 3-18, the first color tone correction layer includes titanium oxide fine particles and an active energy ray-curable resin, and has a refractive index of 1.75 to 1.83 and a film thickness of 400 nm. The second color tone correction layer has a refractive index of 1.33 to 1.53 and a film thickness of 10 to 40 nm, and the tin-doped indium oxide layer has a refractive index of 400 nm. Is 1.85 to 2.35, and the film thickness is 5 to 50 nm, the value of the transmitted color b ^* is small, coloring is sufficiently suppressed, and excellent total light transmittance is realized, and warpage after heat treatment And a transparent conductive film having good crack resistance.

On the other hand, in Comparative Example 2-1, the metal oxide fine particles used in the first color tone correction layer were zirconium oxide, and the transparent color b ^* was large, resulting in the transparent conductive film being colored.

  In Comparative Example 2-2, since the hard coat layer was laminated on the surface of the polyester film base on which the ITO layer was formed, the result was that the film cracked due to the load. Referring to the results of Examples 1-2 to 1-10 and Examples 1-13 to 1-16 together, when the hard coat layer is provided, it is opposite to the side on which the ITO layer of the polyester film base is formed. It turns out that it can suppress that a crack arises by forming in the side.

In Comparative Examples 2-3 to 2-12, since the relative balance of any of the refractive index and film thickness of the first color tone correction layer, the second color tone correction layer, and the tin-doped indium oxide layer is poor, the transmitted color b ^* The value was large and the transparent conductive film was colored, or the total light transmittance was low.

Claims (11)

A color correction preliminary film in which a first color correction layer is laminated on one side of a polyester film substrate,
The first color tone correction layer includes titanium oxide fine particles and an active energy ray-curable resin, and has a refractive index of 1.75 to 1.83 and a film thickness of 32 to 70 nm with respect to light having a wavelength of 400 nm. . A second color correction layer is laminated on the first color correction layer of the color correction preliminary film according to claim 1,
The second color tone correction layer is a color tone correction film having a refractive index of 1.33 to 1.53 and a film thickness of 10 to 40 nm with respect to light having a wavelength of 400 nm.   The color tone correction film according to claim 2, wherein the second color tone correction layer includes silica fine particles and an active energy ray-curable resin, and is formed by a wet film forming method.   The color tone correction film according to claim 2, wherein the second color tone correction layer is made of silicon oxide and is formed by a dry film forming method. A tin-doped indium oxide layer is laminated on the second color correction layer of the color correction film according to any one of claims 2 to 4,
The tin-doped indium oxide layer is a transparent conductive film having a refractive index of 1.85 to 2.35 and a film thickness of 5 to 50 nm with respect to light having a wavelength of 400 nm.   The color tone correction preliminary film according to claim 1, wherein a functional layer is laminated on the other surface of the polyester film substrate.   The color correction film as described in any one of Claims 2-4 by which the functional layer is laminated | stacked on the other surface of the said polyester film base material.   The transparent conductive film according to claim 5, wherein a functional layer is laminated on the other surface of the polyester film substrate.   The color correction preliminary film according to claim 6, wherein the functional layer is one or both of a hard coat layer and a transmittance improving layer.   The color correction film according to claim 7, wherein the functional layer is one or both of a hard coat layer and a transmittance improving layer.   The transparent conductive film according to claim 8, wherein the functional layer is one or both of a hard coat layer and a transmittance improving layer.

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