JP2017170893A - Optically transparent conductive film, and method for producing the optically transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optically transparent conductive film in which the pattern of a conductive layer is hard to be visible.SOLUTION: There is provided an optically transparent conductive film 1 comprising: a conductive layer 3 including optical transparency and conductivity and a base material film 11 arranged at either surface side of the conductive layer, in which the base material film 11 has an MD direction and a TD direction, and the ratio of the linear expansion coefficient at 110 to 140°C of the optically transparent conductive film 1 in the TD direction of the base material film 11 to the linear expansion coefficient at 110 to 140°C of the optically transparent conductive film 1 in the MD direction of the base material film 11 is 1.3 or higher, preferably, 1.8 or higher, and the linear expansion rate at 110 to 140°C of the optically transparent conductive film 1 in the TD direction of the base material film 11 is 100 ppm/°C or lower.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light-transmitting conductive film having light transmittance and conductivity and a method for producing the light-transmitting conductive film.

  In recent years, touch panel 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 substrate is used.

  The following Patent Document 1 discloses a transparent conductive film having a transparent conductive film, a plastic film, and a protective film in this stacking order, and a plastic film with a protective film (light transmissive conductive film). The protective film has a linear expansion coefficient of the first film whose thermal shrinkage after heating at 150 ° C. and 30 minutes is 0.5% or less in both the MD and TD directions, and the plastic film with the transparent conductive film and the protective film. And a second film having a linear expansion coefficient that is 40 ppm / ° C. or less. On the surface of the plastic film, the first film and the second film are provided in this stacking order.

JP-A-11-268168

  An electrode used in a liquid crystal display device is formed by patterning a conductive layer, and the reflection intensity due to external light differs between a portion where the conductive layer is present and a portion where the conductive layer is not present. Therefore, there is a problem that the pattern of the conductive layer is visually recognized (problem of bone appearance). Further, in the conventional light-transmitting conductive film, particularly when the conductive layer is patterned, the film is likely to deform (warp) along the pattern due to internal stress of the ITO film, and the angle of reflected light changes due to the deformation. Therefore, there is a problem that the pattern is more easily visually recognized.

  An object of the present invention is to provide a light transmissive conductive film in which a pattern of a conductive layer is hardly visually recognized and a method for producing the light transmissive conductive film.

  According to a wide aspect of the present invention, it comprises a conductive layer having optical transparency and conductivity, and a base film disposed on one surface side of the conductive layer, and the base film is in the MD direction. The linear expansion coefficient at 110 ° C. to 140 ° C. of the light-transmitting conductive film in the TD direction of the base film, and 110 ° C. of the light-transmitting conductive film in the MD direction of the base film. A light-transmitting conductive film having a ratio of the linear expansion coefficient at 140 ° C. or lower of 1.3 or higher is provided.

  On the specific situation with the transparent conductive film which concerns on this invention, the MD direction of the said base film of the linear expansion coefficient in 110 to 140 degreeC of the transparent conductive film in the TD direction of the said base film The ratio with respect to the linear expansion coefficient in 110 degreeC or more and 140 degrees C or less of the transparent conductive film in is 1.8 or more.

  On the specific situation with the transparent conductive film which concerns on this invention, the linear expansion coefficient in 110 to 140 degreeC of the transparent conductive film in the TD direction of the said base film is 100 ppm / degrees C or less.

  According to a wide aspect of the present invention, there is provided a method for producing the above-described light-transmissive conductive film, the step of obtaining a base film having an MD direction and a TD direction, and one surface of the obtained base film A step of forming a conductive layer on the side, and after the step of obtaining the base film and before the step of forming the conductive layer, the base film is not heated to a temperature exceeding 100 ° C. A method for producing a conductive film is provided.

  The light-transmitting conductive film according to the present invention includes a light-transmitting and conductive conductive layer and a base film disposed on one surface side of the conductive layer, and the base film is , Having a MD direction and a TD direction, and having a linear expansion coefficient of 110 to 140 ° C. of the light-transmitting conductive film in the TD direction of the base film, the light-transmitting conductivity in the MD direction of the base film Since the ratio of the film to the linear expansion coefficient at 110 ° C. or more and 140 ° C. or less is 1.3 or more, the pattern of the conductive layer can be made difficult to be visually recognized.

FIG. 1 is a cross-sectional view showing a light-transmitting conductive film according to the first embodiment of the present invention. FIG. 2 is a sectional view showing a light transmissive conductive film according to the second embodiment of the present invention. FIG. 3 is a cross-sectional view showing a state where the conductive layer of the light transmissive conductive film according to the first embodiment of the present invention is a patterned conductive layer. FIG. 4 is a perspective view showing a state where the light transmissive conductive film according to the first embodiment of the present invention is wound in a roll shape.

  Details of the present invention will be described below.

  The light transmissive conductive film according to the present invention includes a conductive layer and a base material. The conductive layer has light transmittance and conductivity. The base material is disposed on one surface side of the conductive layer. The light transmissive conductive film according to the present invention includes a base film as the whole or a part of the base. The base film is disposed on one surface side of the conductive layer. The base film may be disposed so as to be in direct contact with one surface of the conductive layer, or may be disposed on one surface of the conductive layer with another layer interposed therebetween.

  In the light-transmitting conductive film according to the present invention, the base film has an MD direction and a TD direction. For example, when a base film such as a resin film is produced by a melt extrusion method and is a melt extrusion film, the base film has an MD direction and a TD direction. The MD direction is the flow direction, for example, the length direction. The TD direction is a direction orthogonal to the flow direction, for example, the width direction.

  In the light transmissive conductive film according to the present invention, the linear expansion coefficient (ppm / ° C.) of the light transmissive conductive film in the TD direction of the base film at 110 ° C. or higher and 140 ° C. or lower in the MD direction of the base film. The ratio (linear expansion coefficient in the TD direction / linear expansion coefficient in the MD direction) to the linear expansion coefficient (ppm / ° C.) at 110 ° C. or more and 140 ° C. or less of the light-transmitting conductive film at 1.3 is 1.3 or more.

  In this invention, since said structure is provided, the pattern of a conductive layer can be made difficult to visually recognize. In addition, the light-transmitting conductive film may be cut into a predetermined size when used. In the present invention, the pattern of the conductive layer can be made difficult to be visually recognized no matter which direction the side of the light transmissive conductive film is cut. Moreover, in this invention, when patterning a conductive layer, it is hard to deform | transform. This also makes it difficult to visually recognize the pattern of the conductive layer. In general, from the viewpoint of film uniformity, it is expected that the difference between the linear expansion coefficient in the MD direction and the linear expansion coefficient in the TD direction should be small, but in the present invention, the linear expansion coefficient in the MD direction is By making the difference in the linear expansion coefficient with the TD direction comparatively large and making the ratio (linear expansion coefficient in the TD direction / linear expansion coefficient in the MD direction) equal to or higher than the above lower limit, the pattern of the conductive layer is hardly visually recognized. Was found to be.

  From the viewpoint of making the pattern of the conductive layer more difficult to visually recognize, the above ratio (linear expansion coefficient in the TD direction / linear expansion coefficient in the MD direction) is preferably 1.8 or more. The upper limit of the ratio (linear expansion coefficient in the TD direction / linear expansion coefficient in the MD direction) is not particularly limited. The ratio (linear expansion coefficient in the TD direction / linear expansion coefficient in the MD direction) may be 3.0 or less.

  From the viewpoint of making the pattern of the conductive layer more difficult to visually recognize, the linear expansion coefficient of the light-transmitting conductive film in the TD direction of the substrate film at 110 ° C. or higher and 140 ° C. or lower is preferably 80 ppm / ° C. or higher. Also, it is preferably 120 ppm / ° C. or less, more preferably 100 ppm / ° C. or less.

  The linear expansion coefficient can be evaluated by measuring the light-transmitting conductive film to a predetermined temperature using a thermomechanical analyzer (TMA).

  The substrate includes a substrate film, preferably includes a hard coat layer, and preferably includes an undercoat layer. The light-transmitting conductive film according to the present invention includes a protective film, the conductive layer is disposed on the first surface of the base material, and the second opposite to the first surface of the base material. It is preferable that the said protective film is arrange | positioned on the surface of this.

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

  When the light-transmitting conductive film according to the present invention is used in a liquid crystal display device, the pattern of the conductive layer can be made difficult to be visually recognized, and the display quality can be improved. Therefore, the light-transmitting conductive film according to the present invention can be suitably used for a liquid crystal display device and can be 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 cross-sectional view showing a light-transmitting conductive film according to the first embodiment of the present invention.

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

  The substrate 2 has a first surface 2a and a second surface 2b. The first surface 2a and the second surface 2b are opposed to each other. A conductive layer 3 is laminated on the first surface 2 a of the substrate 2. The first surface 2a is a surface on the side where the conductive layer 3 is laminated. The substrate 2 is a member disposed between the conductive layer 3 and the protective film 4 and is a support member for the conductive layer 3.

  A protective film 4 is laminated on the second surface 2 b of the substrate 2. The second surface 2b is a surface on the side where the protective film 4 is laminated. By providing the protective film 4, the second surface 2 b of the substrate 2 can be protected.

  The substrate 2 includes a substrate film 11, first and second hard coat layers 12 and 13, and an undercoat layer 14. The base film 11 is made of a material having high light transmittance. On the surface of the base film 11 on the conductive layer 3 side, a second hard coat layer 13 and an undercoat layer 14 are laminated in this order. The undercoat layer 14 is in contact with the conductive layer 3.

  A first hard coat layer 12 is laminated on the surface of the base film 11 on the protective film 4 side. The first hard coat layer 12 is in contact with the protective film 4.

  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 of the base material by an adhesive layer. It is preferable that the 2nd surface of a base material is in contact with the said adhesive layer of a protective film.

  In this embodiment, the base film 11 has an MD direction and a TD direction, and the above ratio of the light-transmissive conductive film 1 (linear expansion coefficient in the TD direction / linear expansion coefficient in the MD direction) has a specific lower limit. Satisfied.

  FIG. 2 is a sectional view showing a light transmissive conductive film according to the second embodiment of the present invention.

  A light transmissive conductive film 1A shown in FIG. 2 is a light transmissive conductive film before annealing. In the light transmissive conductive film 1A, the first hard coat layer is not provided. The light transmissive conductive film 1A has a base 2A in which an undercoat layer 14, a second hard coat layer 13, and a base film 11 are laminated in this order. In the light transmissive conductive film 1 </ b> A, the protective film 4 is laminated directly on the surface of the base film 11 opposite to the conductive layer 3.

  In the light transmissive conductive film according to the present invention, the first hard coat layer may not be provided like the light transmissive conductive film 1A. A protective film may be directly laminated on the surface of the base film. Further, at least one of the second hard coat layer and the undercoat layer may not be provided. On the surface of the base film on the conductive layer side, the undercoat layer and the conductive layer may be laminated in this order, or the conductive layer may be laminated directly on the base film. The undercoat layer may be a single layer or a multilayer.

  The method for producing a light-transmitting conductive film according to the present invention includes a step of obtaining a base film having an MD direction and a TD direction, and a step of forming a conductive layer on one surface side of the obtained base film. Prepare. Since it is easy to control the ratio (linear expansion coefficient in the TD direction / linear expansion coefficient in the MD direction) within a suitable range, in the method for producing a light-transmissive conductive film according to the present invention, the base film is It is preferable not to heat the base film to a temperature exceeding 100 ° C. after the obtaining step and before the step of forming the conductive layer.

  After the step of obtaining the base film, the step of forming the first hard coat layer may be performed before the step of forming the conductive layer. When the first hard coat layer is provided, in the step of forming the first hard coat layer, it is preferable not to heat the base film to a temperature exceeding 100 ° C. After the step of obtaining the base film, the step of forming the second hard coat layer may be performed before the step of forming the conductive layer. When the second hard coat layer is provided, in the step of forming the second hard coat layer, it is preferable not to heat the base film to a temperature exceeding 100 ° C. A step of forming the undercoat layer may be performed after the step of obtaining the base film and before the step of forming the conductive layer. When the undercoat layer is provided, it is preferable that the base film is not heated to a temperature exceeding 100 ° C. in the step of forming the undercoat layer.

  Next, a method for manufacturing the light transmissive 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.

  A first hard coat layer 12 is formed on one surface of the base film 11. Specifically, when an ultraviolet curable resin is used as the resin, a photocurable monomer and a photoinitiator are stirred in a diluent to prepare a coating solution. 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.

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

  Next, the second hard coat layer 13 is formed on the surface of the base film 11 opposite to the first hard coat layer 12. Specifically, when an ultraviolet curable resin is used as the resin, a photocurable monomer and a photoinitiator are stirred in a diluent to prepare a coating solution. The obtained coating liquid is applied on the surface of the base film 11 opposite to the first hard coat layer 12 side, and the resin is cured by irradiating with ultraviolet rays to form the second hard coat layer 13. To do.

Next, the undercoat layer 14 is formed on the second hard coat layer 13. Specifically, when SiO ₂ is used, the undercoat layer 14 can be formed on the second hard coat layer 13 by vapor deposition or sputtering.

  As described above, the first and second hard coat layers 12 and 13 and the undercoat layer 14 are formed on the base film 11. In the present invention, the first and second hard coat layers 12 and 13 and the undercoat layer 14 may not be provided. In this case, the surface of the base film 11 on the conductive layer 3 side is the first surface 2 a of the base material 2, and the surface of the base film 11 on the protective film 4 side is the second surface of the base material 2. It is the surface 2b.

  Next, the light-transmitting conductive film 1 can be produced by forming the conductive layer 3 on the undercoat layer 14.

  The method for forming the conductive layer is not particularly limited. For example, a method of etching a metal film formed by vapor deposition or sputtering, various printing methods such as screen printing or inkjet printing, and a known patterning method such as a photolithography method using a resist can be used. The formed conductive layer can be improved in crystallinity by annealing.

  As shown in FIG. 3, the light transmissive conductive film 1 can be used as the light transmissive conductive film 1X by making the conductive layer 3 (FIG. 1) a patterned conductive layer 3X. 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 film 11 side and performing an etching process. 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 3 </ b> X is partially stacked on the first surface 2 a of the substrate 2. The light transmissive conductive film 1 </ b> X has, on the first surface 2 a of the substrate 2, a portion with the patterned conductive layer 3 </ b> X and a portion without the patterned conductive layer 3 </ b> X.

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

  The treatment time for the annealing treatment is preferably 5 minutes or more, more preferably 10 minutes or more, preferably 60 minutes or less, more preferably 30 minutes or less.

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

  Moreover, the light-transmitting conductive films 1, 1 </ b> A, 1 </ b> X shown in FIGS. 1 to 3 may be wound in a roll shape.

  A roll body 51 (light transmissive conductive film) shown in FIG. 4 includes a winding core 61 and a light transmissive conductive film 1. The light transmissive conductive film 1 is wound in a roll shape on the outer periphery of the winding core 61. Thus, the light transmissive conductive film may be wound in a roll shape in the MD direction of the base film.

  Hereinafter, the detail of each layer which comprises a translucent conductive film is demonstrated.

(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. Accordingly, the material of the base film is not particularly limited. For example, polyolefin, polyethersulfone, polysulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate. Examples include phthalate, triacetylcellulose, and cellulose nanofiber. The material for the base film may be used alone or in combination.

  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 even less visible.

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

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

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 Such as triisopropylene glycol diacrylate, polyethylene glycol diacrylate and bisphenol A dimethacrylate Triacrylate compounds such as trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol monohydroxytriacrylate and trimethylolpropane triethoxytriacrylate; of pentaerythritol tetraacrylate and di-trimethylolpropane tetraacrylate And tetraacrylate compounds such as dipentaerythritol (monohydroxy) pentaacrylate. As the ultraviolet curable resin, a polyfunctional acrylate compound may be used, and as the polyfunctional acrylate compound, a polyfunctional acrylate compound having five or more functions may be used. The said polyfunctional acrylate compound may be used independently and may use multiple together. Moreover, you may add a photoinitiator, a photosensitizer, a leveling agent, a diluent, etc. to the said polyfunctional acrylate compound.

  Moreover, the 1st hard-coat layer may be comprised with the resin part and the filler. When the first hard coat layer contains a filler, the pattern of the conductive layer can be made even less visible. Note that when the first hard coat layer contains a filler, fogging due to surface roughness may occur, and when used in a liquid crystal display device, display light may be difficult to see. Therefore, from the viewpoint of making it difficult to cause fogging, it is desirable that the first hard coat layer is composed of only the resin portion without containing the filler. Or it is preferable that the average particle diameter of a filler is smaller than the thickness of a 1st hard-coat layer, and the said filler does not protrude in the surface of a 1st hard-coat layer.

  Examples of the filler include, but are not limited to, metal oxides such as silica, iron oxide, aluminum oxide, zinc oxide, titanium oxide, silicon dioxide, antimony oxide, zirconium oxide, tin oxide, cerium oxide, and indium-tin oxide. Product particles; resin particles such as silicone, (meth) acryl, styrene, melamine, and the like. More specifically, resin particles such as crosslinked poly (meth) methyl acrylate can be used as the filler. The said filler may be used independently and may use multiple together.

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

Undercoat layer;
The undercoat layer is, for example, a refractive index adjustment layer. By providing the undercoat layer, the difference in refractive index between the conductive layer and the second hard coat layer or substrate film can be reduced, so that the light transmissive conductive film can be made more transparent. Can be increased.

The material constituting the undercoat layer is not particularly limited as long as it has a refractive index adjustment function, inorganic materials such as SiO ₂ , MgF ₂ , Al ₂ O ₃ , acrylic resin, urethane resin, melamine resin, alkyd resin, and the like Organic materials such as siloxane polymers can be mentioned.

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

(Conductive layer)
The conductive layer is made of a light-transmitting conductive material. As the conductive material is not particularly limited, for example, IZO (indium zinc oxide) or, In-based oxides such as ITO (indium tin _oxide), Sn, such as SnO 2, FTO (fluorine-doped tin oxide) Oxide, AZO (aluminum zinc oxide), Zn oxide such as 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 said electroconductive material may be used independently and may use multiple together.

From the viewpoint of further increasing the conductivity and further increasing the light transmittance, the conductive material is selected from In-based oxides such as IZO (indium zinc oxide) and ITO (indium tin oxide), SnO ₂ , 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, still more preferably 17 nm or more, preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 19.9 nm or less.

  When the thickness of the conductive layer is not less than the above lower limit, the resistance value of the light transmissive conductive film can be effectively reduced, and the conductivity can be further increased. 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 less visible 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)
It is preferable that the protective film is comprised by the base material sheet and the adhesive layer.

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

  The pressure-sensitive adhesive layer can 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 force 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 in which a crosslinking agent, a tackifier resin, various stabilizers, and the like are added to a (meth) acrylic polymer as necessary.

  The (meth) acrylic polymer is not particularly limited, but the (meth) acrylic copolymer obtained by copolymerizing a mixed monomer containing a (meth) acrylic acid ester monomer and another polymerizable monomer capable of copolymerization. A polymer is preferred.

  Although it does not specifically limit as said (meth) acrylic acid ester monomer, It is obtained by esterification reaction of the primary or secondary alkyl alcohol whose carbon number of an alkyl group is 1-12, and (meth) acrylic acid ( A (meth) acrylate monomer is preferable, and specific examples include ethyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylate-2-ethylhexyl. The said (meth) acrylic acid ester monomer may be used independently and may use multiple together.

  Examples of other polymerizable monomers that can be copolymerized include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and 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, malein Examples thereof include functional monomers such as acid and fumaric acid. The said other polymerizable monomer which can be copolymerized may be used independently, and may use multiple together.

  The crosslinking agent is not particularly limited, and for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, a melamine crosslinking agent, a peroxide crosslinking agent, a urea crosslinking agent, a metal alkoxide crosslinking agent, a metal chelate crosslinking 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.

  The tackifying resin is not particularly limited, and examples thereof include petroleum resins such as aliphatic copolymers, aromatic copolymers, aliphatic / aromatic copolymers, and alicyclic copolymers. Coumarone-indene resin; terpene resin; terpene phenol resin; rosin resin such as polymerized rosin; phenol resin; xylene resin. The tackifying resin may be a hydrogenated resin. The tackifying 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 even less visible.

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

Example 1
A PET film (“Diafoil” manufactured by Mitsubishi Plastics, thickness 50 μm) was prepared as a base film. 5 parts by weight of urethane acrylate oligomer (Arakawa Chemical Industries “Beam Set 575”), 3 parts by weight of photopolymerization initiator (Ciba Specialty Chemicals “Irgacure 184”), and MIBK / MEK mixed solvent (methyl isobutyl) A liquid first hard coat layer material (solid content concentration: 30 wt%) was prepared using ketone (MIBK) and methyl ethyl ketone (MEK) in a ratio of 5: 5 (weight ratio).

The first hard coat layer material is coated on the surface of the base film using a bar coater, and the coating film is dried at 100 ° C. for 2 minutes using a dryer oven (drying conditions). And dried with heat. Next, the first hard coat layer having a thickness of 1.5 μm was provided on the base film by irradiating the dried coating film with ultraviolet rays (irradiation amount: 300 mJ / cm ² ).

  100 parts by weight of zirconium oxide having an average particle size of 30 nm, 50 parts by weight of a photopolymerizer-containing urethane acrylate oligomer (“KAYANOVA FOP4000” manufactured by Nippon Kayaku Co., Ltd.), a MIBK / MEK mixed solvent (methyl isobutyl ketone (MIBK)) A liquid second hard coat layer material (solid content concentration: 5% by weight) was prepared using methyl ethyl ketone (MEK) in a ratio of 5: 5 (weight ratio).

The second hard coat layer material is coated on the surface opposite to the first hard coat layer side of the base film provided with the first hard coat layer, using a bar coater. The membrane was heated and dried using a dryer oven at 100 ° C. for 1 minute (drying conditions). Next, the coated film after drying was irradiated with ultraviolet rays (irradiation amount: 400 mJ / cm ² ) to provide a second hard coat layer having a thickness of 0.8 μm on the base film.

On the outer surface of the second hard coat layer of the base film provided with the first and second hard coat layers, a SiO ₂ layer is formed by reactive sputtering using a Si target material using a magnetron sputtering apparatus. A film was formed to form an undercoat layer. Specifically, after evacuating the inside of the chamber to 5 × 10 ⁻⁴ Pa or less, a mixed gas (Ar gas: oxygen gas = 2: 1) is introduced into the chamber, and the pressure in the chamber is set to 0.4 Pa. Sputtering was performed. The obtained undercoat layer had a refractive index of 1.49 and a thickness of 20 nm.

Next, on the undercoat layer, a transparent conductive material covering the entire surface of the undercoat layer by a DC magnetron sputtering method using a sintered body material of indium oxide: 93 wt% and tin oxide: 7 wt% as a target material. A layer was formed. Specifically, after evacuating the inside of the chamber to 5 × 10 ⁻⁴ Pa or less, a mixed gas (Ar gas: oxygen gas = 95: 5) is introduced into the chamber, and the pressure in the chamber is set to 0.2. Sputtering was performed at ˜0.3 Pa. Sputtering was performed so that the finally obtained transparent conductive layer had a thickness of 18 nm. In order to crystallize the transparent conductive layer (ITO film), reduce resistance, and make it transparent, heat treatment was performed at 150 ° C. for 1 hour in a hot-air circulating oven to obtain a light-transmitting conductive film.

(Example 2)
A light-transmitting conductive film was obtained in the same manner as in Example 1 except that the thickness of the second hard coat layer was changed to 1.5 μm.

(Example 3)
A PET film (“Lumirror” manufactured by Toray Industries Inc., thickness 50 μm) was prepared as a base film.

  Except for changing the base film to the above PET film, changing the thickness of the second hard coat layer to 1.0 μm, and changing the thickness of the first hard coat layer to 2.5 μm. In the same manner as in Example 1, a light transmissive conductive film was obtained.

Example 4
The same as in Example 1 except that the drying conditions after coating the first hard coat layer material were changed to 80 ° C. and 5 minutes, and the second hard coat layer was not formed. A light transmissive conductive film was obtained.

(Comparative Example 1)
A light transmissive conductive film was obtained in the same manner as in Example 1 except that the second hard coat layer was not formed.

(Comparative Example 2)
A light-transmitting conductive film was obtained in the same manner as in Example 3 except that the thickness of the first hard coat layer was changed to 1.5 μm.

(Comparative Example 3)
The substrate film provided with the first and second hard coat layers before sputtering was heated at 150 ° C. for 10 minutes, and then the SiO ₂ layer was formed by sputtering. A transparent conductive film was obtained.

(Comparative Example 4)
The drying conditions after coating the first hard coat layer material were changed to 120 ° C. and 2 minutes, and the drying conditions after coating the second hard coat layer material were 120 ° C. and 1 minute. A light-transmissive conductive film was obtained in the same manner as in Example 1 except that the conditions were changed.

(Evaluation)
(1) Linear expansion coefficient of light transmissive conductive film The linear expansion coefficient of the light transmissive conductive film was measured under the following conditions using a thermomechanical analyzer (“TMA / SS120C” manufactured by Seiko Instruments Inc.). The light-transmitting conductive film after the heat treatment was cut into a size of 3 mm × 25 mm. By measuring from 25 ° C. to 150 ° C. under conditions of a tensile load of 2.94 × 10 ⁻² N and a rate of temperature increase of 5 ° C./min, the cut light transmissive conductive film from 110 ° C. to 140 ° C. The average linear expansion coefficient was measured. The average linear expansion coefficient was calculated by dividing the expansion coefficient when heated from 110 ° C. to 140 ° C. by the temperature difference of 30 ° C. In Table 1, the linear expansion coefficient of the light-transmitting conductive film in the TD direction of the base film at 110 to 140 ° C. is Ct, and the light-transmitting conductive film in the MD direction of the base film is 110 to 140 ° C. The linear expansion coefficient was described as Cm.

(2) Evaluation of bone appearance About the obtained light-transmitting conductive film, bone appearance was evaluated according to the following criteria.

[How to create a bone appearance evaluation sample]
A light transmissive conductive film is cut into 5 cm square, a 200 μm wide line and space resist pattern is exposed and developed on the conductive layer, and immersed in an ITO etching solution (“ITO-06N” manufactured by Kanto Chemical Co., Ltd.) for 1 minute. After rinsing and drying, the resist pattern was removed to obtain a light-transmitting conductive film having a patterned conductive layer.

  As the light source, an LED, a fluorescent lamp, and a white lamp were used, and the arrangement of the light transmissive conductive film patterned with the electric lamp was adjusted so that the patterned conductive layer side was directly under each electric lamp. The light transmissive conductive film was observed from an angle of 45 degrees with respect to the surface of the light transmissive conductive film, and a reflection image of the lamp was observed when the light received from the front of the lamp was reflected by the light transmissive conductive film. . The observed reflected image (the image of the electric lamp by the reflected light reflected from the front of the electric lamp) was judged according to the following evaluation criteria.

[Judgment criteria for bone appearance evaluation]
○○: The pattern of the conductive layer is not visually recognized when irradiated with any of the LED light, the fluorescent lamp, and the white lamp. ○ ... When the LED light is irradiated, the conductive layer pattern is visually recognized. When the fluorescent lamp is irradiated, the pattern of the conductive layer is not visually recognized. X: When the LED light or the fluorescent lamp is irradiated, the conductive layer pattern is visually recognized.

  The results are shown in Table 1 below.

  In Comparative Example 1, the linear expansion coefficient in the MD direction was increased because the second hard coat layer was not formed.

  In Comparative Example 3, the linear expansion coefficient in the TD direction was small because the heating was performed before sputtering, and in Comparative Example 4, the drying temperature was high.

DESCRIPTION OF SYMBOLS 1,1A, 1X ... Light-transmissive conductive film 2, 2A ... Base material 2a ... 1st surface 2b ... 2nd surface 3 ... Conductive layer 3X ... Patterned conductive layer 4 ... Protective film 11 ... Base film 12 ... 1st hard coat layer 13 ... 2nd hard coat layer 14 ... Undercoat layer 51 ... Roll body (light transmissive conductive film)
61 ... winding core

Claims (4)

A conductive layer having optical transparency and conductivity, and a base film disposed on one surface side of the conductive layer,
The base film has an MD direction and a TD direction,
The linear expansion coefficient at 110 ° C. or higher and 140 ° C. or lower of the light-transmitting conductive film in the TD direction of the base film, and the line at 110 ° C. or higher and 140 ° C. or lower of the light-transmitting conductive film in the MD direction of the base film. A light transmissive conductive film having a ratio to an expansion coefficient of 1.3 or more.   The linear expansion coefficient at 110 ° C. or higher and 140 ° C. or lower of the light-transmitting conductive film in the TD direction of the base film is the line at 110 ° C. or higher and 140 ° C. or lower of the light-transmitting conductive film in the MD direction of the base film. The light-transmitting conductive film according to claim 1, wherein the ratio to the expansion coefficient is 1.8 or more.   The light transmissive conductive film of Claim 1 or 2 whose linear expansion coefficient in 110 to 140 degreeC of the light transmissive conductive film in the TD direction of the said base film is 100 ppm / degrees C or less. It is a manufacturing method of the transparent conductive film given in any 1 paragraph of Claims 1-3,
Obtaining a base film having an MD direction and a TD direction;
Comprising a step of forming a conductive layer on one surface side of the obtained base film,
A method for producing a light-transmissive conductive film, wherein the base film is not heated to a temperature exceeding 100 ° C. after the step of obtaining the base film and before the step of forming the conductive layer.

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