JP6705678B2 - Light-transmissive conductive film - Google Patents

Description

The present invention relates to a light-transmitting conductive film having light-transmitting property and conductivity.

In recent years, touch panel type liquid crystal display devices have been widely used in electronic devices such as smartphones, mobile phones, notebook computers, tablet PCs, copiers and car navigation systems. In such a liquid crystal display device, a light-transmissive conductive film in which a transparent conductive layer is laminated on a base material is used.

The following Patent Document 1 discloses a light transmissive conductive film including a support, a polymer layer having a specific refractive index, and a conductive layer. Patent Document 1 describes that, as an effect of the invention described in Patent Document 1, generation of rainbow spots is prevented without impairing transparency, and no oligomer is precipitated.

WO2009/116363A1

In the light-transmissive conductive film, there may be a problem of rainbow-colored interference unevenness in which light reflects and reflected lights interfere with each other. This iridescent interference unevenness is called rainbow unevenness.

The light-transmissive conductive film described in Patent Document 1 can suppress rainbow unevenness to some extent. However, even the light-transmissive conductive film described in Patent Document 1 may not have a sufficient effect of suppressing rainbow unevenness.

An object of the present invention is to provide a light transmissive conductive film in which rainbow unevenness is hard to be visually recognized.

According to a wide aspect of the present invention, a conductive layer having light transmissivity and conductivity, a base film disposed on one surface side of the conductive layer, and the conductive layer side of the base film is With a hard coat layer disposed on the opposite side, in a state in which reflected light from the conductive layer of the light-transmitting conductive film is blocked, on the side opposite to the base film side of the hard coat layer. Provided is a light-transmissive conductive film in which the amplitude of an interference wave of the reflectance of light at a wavelength of 500 nm or 600 nm on the surface is less than 0.5%.

In a particular aspect of the light-transmitting conductive film according to the present invention, the light-transmitting conductive film comprises an undercoat layer, the undercoat layer is arranged on the side opposite to the conductive layer side of the base film. The hard coat layer is disposed on the opposite side of the undercoat layer from the base film side.

In a specific aspect of the light-transmitting conductive film according to the present invention, the refractive index of the undercoat layer is between the refractive index of the base film and the refractive index of the hard coat layer.

In a specific aspect of the light-transmitting conductive film according to the present invention, the optical thickness of the undercoat layer is 125 nm or more and 150 nm or less.

The light-transmitting conductive film according to the present invention is a conductive layer having light-transmitting property and conductivity, a base film disposed on one surface side of the conductive layer, and the conductive layer side of the base film. And a hard coat layer disposed on the opposite side, and in a state where the reflected light from the conductive layer of the light-transmitting conductive film is blocked, the hard coat layer is opposite to the base film side. Since the amplitude of the interference wave of the reflectance of light at the wavelength of 500 nm or 600 nm on the side surface is less than 0.5%, it is possible to make the rainbow unevenness less visible.

FIG. 1 is a sectional view showing a light-transmitting conductive film according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a state in which the conductive layer of the light-transmitting conductive film according to the embodiment of the present invention is a patterned conductive layer. FIG. 3 is a diagram showing measurement results of amplitudes of interference waves of light reflectance at wavelengths of 250 nm or more and 800 nm or less on the surface of the hard coat layer on the side opposite to the base film side in Examples and Comparative Examples. .. FIG. 4 is a diagram for explaining the amplitude of an interference wave of light reflectance.

Hereinafter, the details of the present invention will be described.

The light-transmitting conductive film according to the present invention includes a conductive layer and a base material. The conductive layer has optical transparency and conductivity. The base material is arranged on one surface side of the conductive layer. The light transmissive conductive film according to the present invention includes a substrate film and a hard coat layer as the whole or a part of the substrate.

The base film is arranged on one surface side of the conductive layer. The hard coat layer is arranged on the side of the base film opposite to the side of the conductive layer.

In the light-transmitting conductive film, the conductive layer, (other layers (optional)), the base film, (other layers such as an undercoat layer (optional)), and the hard coat layer are arranged in this order. ing.

In the state where the reflected light from the conductive layer of the light-transmitting conductive film according to the present invention is blocked, the light of wavelength 500 nm or 600 nm on the surface of the hard coat layer opposite to the base film side is The amplitude of the interference wave of reflectance is less than 0.5%. In order to make the reflected light from the conductive layer of the light-transmissive conductive film blocked, for example, a light non-transmissive member may be arranged on the side opposite to the base film side of the conductive layer.

In the present invention, since the above configuration is provided, it is possible to make rainbow spots less visible. Further, even if the thickness of the hard coat layer varies, it is possible to make rainbow unevenness less visible. In the present invention, since the amplitude of the interference wave of the reflectance of light at the wavelength of 500 nm or 600 nm is less than the above upper limit, the amplitude of the interference wave of the reflectance of light at the wavelength with high visibility (for example, near 550 nm) is suppressed. Therefore, it is possible to make the rainbow unevenness less visible.

The wavelength of light and the reflectance of light show the relationship as shown in FIG. 3, for example. As the wavelength of light increases, the reflectance of light repeatedly decreases and increases. As shown in FIG. 4 by enlarging a part of FIG. 3, the reflectance of the light at the first point where the reflectance of the light changes from an increase to a decrease, and the reflectance changes from an increase to a decrease and then to an increase. The absolute value of the difference from the reflectance of the light at the second point is the amplitude of one interference wave. As shown in FIG. 3, there are a plurality of amplitudes (amplitudes connecting the first point and the second point) of the interference wave having the light reflectance. Among a plurality of amplitudes of interference waves of light reflectance (a plurality of amplitudes connecting a first point and a second point), an amplitude including a wavelength 500nm portion is an amplitude at a wavelength 500nm. Among the plurality of amplitudes of the interference wave of the light reflectance (the plurality of amplitudes connecting the first point and the second point), the amplitude including the wavelength 600nm portion is the amplitude at the wavelength 600nm.

In the present invention, only the amplitude of the interference wave of the reflectance of light at the wavelength of 500 nm may be less than 0.5%, and only the amplitude of the interference wave of the reflectance of light at the wavelength of 600 nm is less than 0.5%. It is also possible that both the amplitude of the interference wave of the reflectance of light at the wavelength of 500 nm and the amplitude of the interference wave of the reflectance of the light at wavelength of 600 nm are less than 0.5%.

The base material includes a base film and a hard coat layer. The base material preferably includes an undercoat layer. From the viewpoint of further suppressing rainbow unevenness, it is preferable that the light-transmitting conductive film has an undercoat layer. The undercoat layer is preferably arranged on the side of the base film opposite to the side of the conductive layer. The hard coat layer is preferably arranged on the side of the undercoat layer opposite to the side of the base film. The undercoat layer is preferably arranged between the base film and the hard coat layer.

The light-transmissive conductive film is preferably an annealed light-transmissive conductive film.

When the light-transmissive conductive film according to the present invention is used in a liquid crystal display device, it is possible to make rainbow unevenness less visible and improve display quality. Therefore, the light transmissive conductive film according to the present invention can be suitably used for a liquid crystal display device and can be more suitably used for a touch panel.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a light-transmitting conductive film according to an embodiment of the present invention.

The light-transmitting conductive film 1 shown in FIG. 1 includes a base material 2, a conductive layer 3 and a protective film 4.

The base material 2 has a first surface 2a and a second surface 2b. The first surface 2a and the second surface 2b face each other. The conductive layer 3 is laminated on the first surface 2 a of the base material 2. The first surface 2a is a surface on the side where the conductive layer 3 is laminated. The base material 2 is a member arranged between the conductive layer 3 and the protective film 4, and is a support member for the conductive layer 3.

The protective film 4 is laminated on the second surface 2b of the base material 2. The second surface 2b is a surface on which the protective film 4 is laminated. By providing the protective film 4, the second surface 2b of the base material 2 can be protected.

The substrate 2 has a substrate film 11, first and second hard coat layers 12, 13 and first, second and third undercoat layers 14, 15, 16. The base film 11 is made of a material having high light transmittance. The second undercoat layer 15, the second hard coat layer 13, and the third undercoat layer 16 are laminated in this order on the surface of the base film 11 on the conductive layer 3 side. A first undercoat layer 14 and a first hard coat layer 12 are laminated in this order on the surface of the base film 11 opposite to the conductive layer 3 side.

Therefore, as a whole, the light-transmissive conductive film 1 includes the conductive layer 3, the third undercoat layer 16, the second hard coat layer 13, the second undercoat layer 15, the base film 11, and the first undercoat layer. It has a structure in which the coat layer 14, the first hard coat layer 12, and the protective film 4 are laminated in this order.

The third undercoat layer 16 is in contact with the conductive layer 3. The second hard coat layer 13 is in contact with the third undercoat layer 16 and the second undercoat layer 15. The second undercoat layer 15 is in contact with the second hard coat layer 13 and the base film 11. The base film 11 is in contact with the second undercoat layer 15 and the first undercoat layer 14. The first hard coat layer 12 is in contact with the first undercoat layer 14 and the protective film 4. The protective film 4 is in contact with the first hard coat layer 12.

The conductive layer 3 is made of a material having high light transmittance and high conductivity.

The protective film may be laminated on the second surface 2b of the base material with an adhesive layer. The second surface 2b of the base material is preferably in contact with the pressure-sensitive adhesive layer of the protective film.

The third undercoat layer 16 may be omitted. The second hard coat layer 13 may be omitted. The second undercoat layer 15 may be omitted. The first undercoat layer 14 may be omitted, but it is preferable to have the first undercoat layer 14.

Next, a method for manufacturing the light-transmitting conductive film 1 shown in FIG. 1 will be described.

The light-transmissive conductive film 1 can be produced, for example, by the following method.

The first undercoat layer 14 is formed on one surface of the base film 11. Specifically, when SiO ₂ is used, the first undercoat layer 14 is formed on the base film 11 by vapor deposition or sputtering, and when an ultraviolet curable resin is used, a coating liquid is applied. can do.

Next, the first hard coat layer 12 is formed on the surface of the first undercoat layer 14 opposite to the base film 11. Specifically, when an ultraviolet curable resin is used as the resin for forming the first hard coat layer 12, the photocurable monomer and the photoinitiator are stirred in a diluent to prepare a coating liquid. The obtained coating liquid is applied onto the base film 11, and the resin is cured by irradiating with ultraviolet rays to form the first hard coat layer 12.

Then, the protective film 4 is formed on the first hard coat layer 12. When a protective film having a pressure-sensitive adhesive layer provided on a base material sheet is used as the protective film 4, the pressure-sensitive adhesive surface is attached to the surface of the first hard coat layer 12, and the first hard coat layer 12 is formed. The protective film 4 can be formed.

Next, the second undercoat layer 15 is formed on the surface of the base film 11 opposite to the first hard coat layer 12. Like the first undercoat layer 14, the second undercoat layer 15 can be formed using SiO ₂ or an ultraviolet curable resin.

Next, the second hard coat layer 13 is formed on the surface of the second undercoat layer 15 opposite to the base film 11. The second hard coat layer 13 can be formed using an ultraviolet curable resin or the like in the same manner as the first hard coat layer 12.

Next, the third undercoat layer 16 is formed on the surface of the second hard coat layer 13 opposite to the second undercoat layer 15. Like the first undercoat layer 14, the third undercoat layer 16 can be formed using SiO _{2, an} ultraviolet curable resin, or the like.

Next, the light transmissive conductive film 1 can be produced by forming the conductive layer 3 on the surface of the third undercoat layer 16 opposite to the second hard coat layer 13.

The method for forming the conductive layer is not particularly limited. For example, a conductive metal oxide film is formed by vapor deposition or sputtering. The formed conductive layer can be enhanced in crystallinity by annealing.

As shown in FIG. 2, the light-transmissive conductive film 1 is formed by using various printing methods such as screen printing or inkjet printing, and a known patterning method such as a photolithography method using a resist and the like. By forming the patterned conductive layer 3X in 1), it can be used as the light transmissive conductive film 1X. A patterned conductive layer 3X can be formed by partially forming a resist layer on the surface of the conductive layer 3 opposite to the base material 2 and performing an etching treatment. After the etching process, washing with water is performed.

The light-transmissive conductive film 1X has a patterned conductive layer 3X. The patterned conductive layer 3X is partially laminated on the first surface 2a of the base material 2. The light-transmissive conductive film 1X has, on the first surface 2a of the base material 2, a portion having the patterned conductive layer 3X and a portion having no patterned conductive layer 3X. The third undercoat layer 16 has a function of making the colors of the portion having the patterned conductive layer 3X and the portion having no patterned conductive layer 3X closer to each other, and makes the pattern of the conductive layer 3X inconspicuous.

The annealing temperature is preferably 120° C. or higher, more preferably 140° C. or higher, preferably 170° C. or lower, more preferably 160° C. or lower.

The annealing time is preferably 5 minutes or longer, more preferably 10 minutes or longer, preferably 60 minutes or shorter, and more preferably 30 minutes or shorter.

The light-transmissive conductive film 1X may be used while the protective film 4 is laminated, or may be used after the protective film 4 is peeled off.

Hereinafter, details of each layer constituting the light-transmitting conductive film will be described.

(Base material)
The total thickness of the substrate is preferably 23 μm or more, more preferably 50 μm or more, preferably 300 μm or less, more preferably 200 μm or less.

(Base film);
The base film preferably has high light transmittance. Therefore, the material of the substrate film is not particularly limited, but for example, polyolefin, polyether sulfone, polysulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene na. Examples thereof include phthalate, triacetyl cellulose, and cellulose nanofiber. The material of the substrate film may be used alone or in combination of two or more.

The thickness of the base film is preferably 5 μm or more, more preferably 20 μm or more, preferably 190 μm or less, more preferably 125 μm or less. When the thickness of the base film is not less than the above lower limit and not more than the above upper limit, the pattern of the conductive layer can be made more difficult to be visually recognized.

Regarding the light transmittance of the substrate film, the average transmittance in the visible light region of wavelength 380 to 780 nm is preferably 85% or more, more preferably 90% or more.

Further, the base film may contain various stabilizers, ultraviolet absorbers, plasticizers, lubricants or colorants.

(Undercoat layer arranged on the side opposite to the conductive layer side of the base film);
From the viewpoint of further suppressing rainbow unevenness, the undercoat layer (first undercoat layer) is preferably disposed on the side of the base film opposite to the side of the conductive layer, and the undercoat layer ( It is preferable that the hard coat layer (first hard coat layer) is disposed on the side opposite to the base film side of the first undercoat layer).

When polyethylene terephthalate, for example, is used as the base film, the surface of the film is highly crystallographically oriented, so that the adhesion to the hard coat layer or the like is poor. Therefore, an undercoat layer is applied so that the coating agent can be applied easily.

The material forming the undercoat layer is not particularly limited, and examples thereof include organic materials such as polyester resin, acrylic resin, urethane resin, melamine resin, alkyd resin, and siloxane polymer.

As a method for applying the undercoat layer to the base film, any known method can be used. Examples of this method include a reverse roll coating method, a gravure coating method, a kiss coating method, a die coater method, a roll brush method, a spray coating method, an air knife coating method, a wire bar coating method, a pipe doctor method, an impregnation coating method, and a curtain. A coating method and the like can be mentioned. Coating is performed by using these methods alone or in combination.

From the viewpoint of further suppressing rainbow unevenness, the refractive index of the undercoat layer (first undercoat layer) arranged on the side opposite to the conductive layer side of the base film is equal to the refractive index of the base film. And the refractive index of the hard coat layer (first hard coat layer) arranged on the side opposite to the base film side of the undercoat layer (first undercoat layer).

From the viewpoint of further suppressing rainbow unevenness, the optical thickness of the undercoat layer arranged on the side opposite to the conductive layer side of the base film, that is, the product of the refractive index and the thickness is preferably 125 nm or more, and more preferably 130 nm. The above is more preferably 135 nm or more, preferably 150 nm or less, more preferably 145 nm or less, still more preferably 140 nm or less.

(First and second hard coat layers);
Each of the first and second hard coat layers is preferably composed of a binder resin. The binder resin is preferably a cured resin. As the curable resin, a thermosetting resin, an active energy ray curable resin, or the like can be used. From the viewpoint of improving productivity and economy, the curable resin is preferably an ultraviolet curable resin.

Examples of the photocurable monomer for forming the ultraviolet curable resin include 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, and tetraethylene glycol diacrylate. , Tripropylene glycol diacrylate, neopentyl glycol diacrylate, 1,4-butanediol dimethacrylate, poly(butanediol) diacrylate, tetraethylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, triethylene glycol diacrylate Diacrylate compounds such as, triisopropylene glycol diacrylate, polyethylene glycol diacrylate and bisphenol A dimethacrylate; trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol monohydroxytriacrylate and trimethylolpropane triethoxytriacrylate. And triacrylate compounds such as pentaerythritol tetraacrylate and di-trimethylolpropane tetraacrylate; and pentaacrylate compounds such as dipentaerythritol (monohydroxy) pentaacrylate. As the ultraviolet curable resin, a polyfunctional acrylate having a functionality of 5 or more may be used. The polyfunctional acrylates may be used alone or in combination of two or more. Moreover, you may add a photoinitiator, a photosensitizer, a leveling agent, a diluent etc. to the said polyfunctional acrylate compound.

Further, the second hard coat layer may be composed of a resin portion and a filler. When the second hard coat layer contains a filler, the pattern of the conductive layer can be made more difficult to be visually recognized. When the second hard coat layer contains a filler, cloudiness may occur due to surface roughness, and when used in a liquid crystal display device, display light may be difficult to see. Therefore, from the viewpoint of making the yuzu skin less likely to occur, it is desirable that the second hard coat layer does not contain a filler and is composed of only the resin portion. Alternatively, the average particle diameter of the filler is preferably smaller than the thickness of the second hard coat layer and does not protrude on the surface of the second hard coat layer.

The filler is not particularly limited, for example, silica, iron oxide, aluminum oxide, zinc oxide, titanium oxide, silicon dioxide, antimony oxide, zirconium oxide, tin oxide, cerium oxide, metal oxide such as indium-tin oxide. Material particles; resin particles such as silicone, (meth)acrylic, styrene and melamine. More specifically, resin particles such as crosslinked poly(meth)acrylate can be used. The fillers may be used alone or in combination of two or more.

Further, the first and second hard coat layers may each contain various stabilizers, ultraviolet absorbers, plasticizers, lubricants or colorants.

(Undercoat layer disposed on the conductive layer side of the base film);
The second undercoat layer arranged on the conductive layer side of the base film is preferably, for example, a refractive index adjusting layer. By providing the second undercoat layer, it is possible to reduce the difference in the refractive index between the conductive layer and the second hard coat layer or the base film. Can be further enhanced.

The material forming the undercoat layer is not particularly limited as long as it has a refractive index adjusting function, and includes inorganic materials such as SiO ₂ , MgF ₂ , and Al ₂ O ₃ , acrylic resins, urethane resins, melamine resins, alkyd resins, and Organic materials such as siloxane polymers may be mentioned.

The undercoat layer can be formed by a vacuum vapor deposition method, a sputtering method, an ion plating method or a coating method.

From the viewpoint of further suppressing the pattern appearance of the conductive layer, the refractive index of the third undercoat layer arranged on the conductive layer side of the base film is the refractive index of the base film, and the second hard coat layer. It is preferable that the refractive index is lower than that of the conductive layer.

From the viewpoint of further suppressing the pattern appearance of the conductive layer, the thickness of the third undercoat layer arranged on the conductive layer side of the base film is preferably 5 nm or more, more preferably 10 nm or more, preferably 50 nm or less, More preferably, it is 30 nm or less.

(Conductive layer);
The conductive layer is formed of a light-transmitting conductive material. The conductive material is not particularly limited, but examples thereof include In-based oxides such as IZO (indium zinc oxide) and ITO (indium tin oxide), SnO ₂ and Sn such as FTO (fluorine-doped tin oxide). -Based oxides, Zn-based oxides such as AZO (aluminum zinc oxide) and GZO (gallium zinc oxide), sodium, sodium-potassium alloy, lithium, magnesium, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum - lithium alloy, Al / _Al 2 _{O 3} mixture, Al / LiF mixture, a metal such as gold, CuI, Ag nanowire (AgNW), such as carbon nanotubes (CNT) or conductive transparent polymers. The above conductive materials may be used alone or in combination of two or more.

From the viewpoint of further increasing the conductivity and further increasing the light transmittance, the conductive material is an In-based oxide such as IZO (indium zinc oxide) or ITO (indium tin oxide), SnO ₂ , or FTO. Sn-based oxides such as (fluorine-doped tin oxide), Zn-based oxides such as AZO (aluminum zinc oxide) and GZO (gallium zinc oxide) are preferable, and ITO (indium tin oxide) is preferable. Is more preferable.

The thickness of the conductive layer is preferably 12 nm or more, more preferably 16 nm or more, further preferably 17 nm or more, preferably 50 nm or less, more preferably 30 nm or less, still more preferably 19.9 nm or less.

When the thickness of the conductive layer is at least the above lower limit, the resistance value of the light-transmitting conductive film can be effectively lowered, and the conductivity can be further enhanced. When the thickness of the conductive layer is less than or equal to the above upper limit, the pattern of the conductive layer can be made more difficult to be visually recognized, and the light transmissive conductive film can be made even thinner.

Regarding the light transmittance of the conductive layer, the average transmittance in the visible light region is preferably 85% or more, more preferably 90% or more.

(Protective film);
The protective film is preferably composed of a base sheet and an adhesive layer.

The substrate sheet preferably has high light transmittance. The material of the base sheet is not particularly limited, but includes, for example, polyolefin, polyether sulfone, polysulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethylmethacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate. , Triacetyl cellulose, and cellulose nanofibers.

The pressure-sensitive adhesive layer may be composed of a (meth)acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a urethane-based adhesive or an epoxy-based adhesive. From the viewpoint of suppressing an increase in adhesive strength due to heat treatment, the adhesive layer is preferably composed of a (meth)acrylic adhesive.

The (meth)acrylic pressure-sensitive adhesive is a pressure-sensitive adhesive obtained by adding a cross-linking agent, a tackifying resin, various stabilizers, etc. to the (meth)acrylic polymer as needed.

The (meth)acrylic polymer is not particularly limited, but is a (meth)acrylic copolymer obtained by copolymerizing a mixed monomer containing a (meth)acrylic acid ester monomer and another copolymerizable polymerizable monomer. It is preferably a polymer.

The (meth)acrylic acid ester monomer is not particularly limited, but is obtained by an esterification reaction between a primary or secondary alkyl alcohol having an alkyl group having 1 to 12 carbon atoms and (meth)acrylic acid ( A (meth)acrylic acid ester monomer is preferable, and specific examples thereof include ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. The (meth)acrylic acid ester monomers may be used alone or in combination of two or more.

Examples of the other polymerizable monomer that can be copolymerized include 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate such as hydroxybutyl (meth)acrylate; Isobornyl (meth)acrylate, hydroxyalkyl (meth)acrylate, glycerin dimethacrylate, glycidyl (meth)acrylate, 2-methacryloyloxyethyl isocyanate, (meth)acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid Functional acids such as acids and fumaric acid are mentioned. The other copolymerizable polymerizable monomer may be used alone or in combination of two or more.

The cross-linking agent is not particularly limited, for example, isocyanate cross-linking agent, epoxy cross-linking agent, melamine cross-linking agent, peroxide cross-linking agent, urea cross-linking agent, metal alkoxide cross-linking agent, metal chelate cross-linking agent. Agents, metal salt crosslinking agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, amine crosslinking agents, polyfunctional acrylates and the like. The above crosslinking agents may be used alone or in combination of two or more.

The tackifying resin is not particularly limited, and examples thereof include petroleum-based resins such as aliphatic copolymers, aromatic copolymers, aliphatic/aromatic copolymers and alicyclic copolymers. Coumarone-indene type resin; terpene type resin; terpene phenol type resin; rosin type resin such as polymerized rosin; phenol type resin; xylene type resin. The tackifying resin may be a hydrogenated resin. The above tackifier resins may be used alone or in combination.

The thickness of the protective film is preferably 25 μm or more, more preferably 50 μm or more, preferably 300 μm or less, more preferably 200 μm or less. When the thickness of the protective film is not less than the above lower limit and not more than the above upper limit, the pattern of the conductive layer can be made more difficult to be visually recognized.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the examples below.

(Example 1)
A light-transmitting conductive film was obtained as follows. The following refractive indices are values at a wavelength of 550 nm.

A first undercoat layer (thickness 82.06 nm, refractive index 1.5809) is formed on the surface on one side, and a second undercoat layer (thickness 85.5 nm, refractive index 1. A PET resin base material (thickness 125 μm, refractive index 1.66) on which 6533) was formed was prepared.

A first hard coat layer (thickness 1370 nm, refractive index 1.5032) is formed by applying a photoreactive coating solution containing an acrylate resin on the first undercoat layer, heating and drying, and then irradiating with ultraviolet rays. Formed.

Next, on the second undercoat layer, as the optical interference layer, a second hard coat layer (thickness: 955 nm, refractive index: 1.661) made of an acrylate resin containing zirconia particles, and an acrylate resin made a third layer. Undercoat layer (thickness: 25 nm, refractive index: 1.51) was formed. Further, ITO (indium tin oxide, thickness 18.5 nm, refractive index 1.93) was formed as a conductive layer on the third undercoat layer via a SiO _x layer for improving adhesion. A transparent conductive film was obtained. Specifically, as a target material, a sintered body material containing 95% by weight of indium oxide and 5% by weight of tin oxide is used to form a SiO _x layer by a DC magnetron sputtering method, and an ITO layer is formed thereon. Formed.

The obtained transparent conductive film was heated in an oven at 140° C. for 30 minutes to obtain a transparent conductive film having a predetermined resistance value (150 Ω/□).

(Example 2)
Changing the first undercoat layer (thickness 82.06 nm, refractive index 1.5809) to the first undercoat layer (thickness 84.39 nm, refractive index 1.5987), and the first hard coat layer A light-transmissive conductive film was obtained in the same manner as in Example 1 except that (thickness 1370 nm, refractive index 1.5032) was changed to the first hard coat layer (thickness 880 nm, refractive index 1.5526). ..

(Example 3)
Changing the first undercoat layer (thickness 82.06 nm, refractive index 1.5809) to the first undercoat layer (thickness 86.69 nm, refractive index 1.5688), and the first hard coat layer A light-transmissive conductive film was obtained in the same manner as in Example 1 except that (thickness 1370 nm, refractive index 1.5032) was changed to the first hard coat layer (thickness 1290 nm, refractive index 1.4832). ..

(Comparative example)
Changing the first undercoat layer (thickness 82.06 nm, refractive index 1.5809) to the first undercoat layer (thickness 99.37 nm, refractive index 1.5708), and the first hard coat layer A light transmissive conductive film was obtained in the same manner as in Example 1 except that (thickness 1370 nm, refractive index 1.5032) was changed to the first hard coat layer (thickness 1315 nm, refractive index 1.5395). ..

(Evaluation)
(1) Measurement of amplitude of interference wave As for reflectance, specular photometer (V-670 manufactured by JASCO Corporation) was used to measure 5 degree regular reflection. The measurement conditions are as follows.

Wavelength range: 800nm to 250nm
Scanning speed: 400 nm/min Data acquisition interval: 1 nm

In addition, the thickness and refractive index of each layer were calculated from the obtained reflectance spectrum. The calculation was performed with WVASE32 (manufactured by JA Woollam).

The outer surface of the conductive layer of the resulting light-transmitting conductive film was ground with a sandpaper No. 400 (manufactured by Sankyo Rikagaku Co., Ltd.) to roughen the surface, and then a black tape (Eslon Tape #360 manufactured by Sekisui Chemical Co., Ltd.) Pasted.

In this way, the relationship between the wavelength of light and the reflectance of the surface of the first hard coat layer on the side opposite to the side of the base film is obtained with the reflected light from the conductive layer of the light transmissive conductive film blocked. Was measured, and the amplitude of the interference wave of the reflectance of light at wavelengths of 500 nm and 600 nm was evaluated.

(2) Rainbow unevenness The obtained light-transmissive conductive film was placed on white paper and visually observed under daylight three-wavelength fluorescent lamp illumination to evaluate the rainbow unevenness. Rainbow unevenness was judged according to the following criteria.

[Rainbow Judgment Criteria]
○○…I don't care about rainbow spots ○…I don't care about rainbow spots △…I'm worried about rainbow spots ×…I see rainbow spots like an oil film clearly

Details and results are shown in Table 1 below.

Further, FIG. 3 shows the measurement results of the amplitude of the interference wave of the reflectance of light at the wavelength of 250 nm or more and 800 nm or less on the surface of the first hard coat layer on the side opposite to the base film side in Examples and Comparative Examples. showed that.

1, 1X... Light transmissive conductive film 2... Base material 2a... First surface 2b... Second surface 3... Conductive layer 3X... Patterned conductive layer 4... Protective film 11... Base film 12... First Hard coat layer 13...Second hard coat layer 14...First undercoat layer 15...Second undercoat layer 16...Third undercoat layer

Claims (3)

A conductive layer having optical transparency and conductivity,
A base film arranged on one surface side of the conductive layer,
An undercoat layer arranged on the side opposite to the conductive layer side of the base film,
A hard coat layer arranged on the side opposite to the base film side of the undercoat layer,
The optical thickness of the undercoat layer is 125 nm or more and 150 nm or less,
The optical thickness of the hard coat layer is 1366.3 nm or more and 2059.4 nm or less,
Interference of light reflectance at a wavelength of 500 nm or 600 nm on the surface of the hard coat layer opposite to the side of the base material film in a state where the reflected light from the conductive layer of the light transmissive conductive film is blocked. A light-transmissive conductive film having a wave amplitude of less than 0.5%. The light-transmissive conductive film according to claim 1, wherein the hard coat layer has a thickness of 880 nm or more and 1370 nm or less. The light transmissive conductive film according to claim 1, wherein the refractive index of the undercoat layer is between the refractive index of the base film and the refractive index of the hard coat layer.

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