JP2017224269A - Transparent conductive film and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film having excellent moisture/heat resistance, and a touch panel equipped with the transparent conductive film.SOLUTION: A transparent conductive film includes, on a transparent resin film, a curable resin layer and a transparent conductive membrane in this order. In the transparent conductive film, the curable resin layer is 100 nm thick or less, and the transparent conductive film is formed into a pattern. In the transparent conductive film, the rate of change of the surface resistance value is 1.5 or less before and after left to stand in an atmosphere at a temperature of 85°C and a humidity of 85% for 240 hours.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transparent conductive film and a touch panel.

  In recent years, in a touch panel display device that has been rapidly spread, a transparent electrode made of a transparent conductive layer such as indium-tin composite oxide (ITO) is used. The conductor with a transparent electrode used for touch panels basically uses glass or plastic film as a substrate, but smartphones and tablets that require portability use plastic film from the viewpoint of thinness and weight. A transparent conductive film is preferably used.

  For the touch panel application, for example, a transparent conductive film having a transparent conductive film patterned on at least one cured resin layer on one surface of a transparent resin film has been proposed (Patent Document 1). .

JP 2009-76432 A

  For touch panel applications installed in smartphones, car navigation systems, etc. that may be placed under high temperature and high humidity, there is no problem in operation even under harsher conditions such as 85 ° C and 85% RH. There is a strong demand for high wet heat durability. However, when the transparent conductive film according to the above technology is subjected to a heat and humidity resistance test at 85 ° C. and 85% RH, cracks are generated in the patterned transparent conductive film, and it is newly found that the electrical characteristics are deteriorated. ing.

  An object of this invention is to provide the touchscreen provided with the transparent conductive film which has the outstanding heat-and-moisture resistance, and the said transparent conductive film.

  As a result of intensive studies to solve the above problems, the inventors of the present application have found that when a transparent conductive film patterned with a transparent conductive film is placed in a high temperature and high humidity environment, the transparent resin film expands due to moisture absorption. It was found that the transparent conductive film could not follow the expansion and cracks in the transparent conductive film were generated. The inventors of the present application have further studied and found that the object can be achieved by adopting the following configuration, and have completed the present invention.

That is, the present invention is a transparent conductive film having a cured resin layer and a transparent conductive film in this order on a transparent resin film,
The cured resin layer is a cured product film obtained by curing a resin composition containing an epoxy resin having a weight average molecular weight of 1500 or more,
The thickness of the cured resin layer is 150 nm or less,
The cured resin layer has a surface elastic modulus of 4 GPa or more and 12 GPa or less.

  In the transparent conductive film, a cured resin layer is formed using a resin composition containing an epoxy resin having a weight average molecular weight of 1500 or more, and the surface elastic modulus of the cured resin layer is 4 GPa or more and 12 GPa or less. And a cured product film having a three-dimensional crosslinked structure can be formed, and the film strength of the cured resin layer is high. Thereby, the water resistance and expansion resistance of the cured resin layer can be improved, and as a result, the moisture and heat resistance of the transparent conductive film when the transparent conductive film is patterned can be improved. If the weight average molecular weight of the epoxy resin is less than 1500 or the surface elastic modulus of the cured resin layer is less than 4 GPa, the film strength of the cured resin layer becomes insufficient, and the moisture and heat resistance of the transparent conductive film decreases. There is a risk. When the surface elastic modulus of the cured resin layer exceeds 12 GPa, the flexibility of the cured resin layer is lowered, and there is a possibility that whitening or cracking may occur when the transparent conductive film is bent.

  The gelation time when the mixture of the resin composition and the epoxy resin curing accelerator is heated at 170 ° C. is preferably 50 seconds or less. The gelation time is generally an indicator of the reactivity of the target composition or the like, particularly the curing reactivity, and the shorter the gelling time, the higher the curing reactivity. By setting the gelation time of the resin composition to which the curing accelerator is added to 50 seconds or less, the curing reaction of the resin composition can be rapidly and sufficiently advanced to form a stronger cured product film. .

  The curing accelerator preferably contains antimony. Since the curing accelerator containing antimony has high reactivity, the curing reaction of the resin composition can be advanced rapidly and sufficiently, and a stronger cured product film can be efficiently formed.

  The epoxy resin is preferably a rubber-modified epoxy resin. Thereby, toughness and impact resistance can be suitably imparted to the cured resin layer.

  It is preferable that the saturation expansion coefficient of the cured resin layer in an atmosphere of 85 ° C. and 85% humidity is 0.5% or less. By setting the saturation expansion coefficient of the cured resin layer in such a range, the moisture and heat resistance of the transparent conductive film is increased, and the stability and certainty of the output of electrical characteristics can be improved.

  The transparent conductive film is patterned, and the change rate of the surface resistance value before and after the transparent conductive film is placed in an atmosphere at a temperature of 85 ° C. and a humidity of 85% for 240 hours is preferably 1.5 or less. . By making the rate of change of the surface resistance value before and after exposure to a high-temperature and high-humidity atmosphere within the above range, even when placed in a harsh environment, the desired electrical characteristics can be exhibited, As a result, various applications can be developed.

  The present invention also relates to a touch panel including the transparent conductive film. Since the said touch panel uses the transparent conductive film with high heat-and-moisture resistance, it can exhibit the outstanding durability and a weather resistance.

It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention. It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention. It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention. It is sectional drawing which shows the transparent conductive film which concerns on one Embodiment of this invention. It is a top view which shows an example of the pattern of the transparent conductive film of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. It should be noted that parts not necessary for the description are omitted, and some parts are illustrated in an enlarged or reduced form for easy explanation.

<First Embodiment>
(Transparent conductive film)
FIG. 1 is a cross-sectional view showing an example of the transparent conductive film of the present embodiment. The transparent conductive film in FIG. 1 has a transparent conductive film 3 on one side of a transparent resin film 1 with a cured resin layer 2 interposed therebetween. The transparent conductive film 3 is patterned. In each figure, the patterning of the transparent conductive film 3 is indicated by having a pattern part a having the transparent conductive film 3 and a non-pattern part b not having the transparent conductive film 3. The non-pattern part b has the cured resin layer 2.

(Transparent resin film)
The transparent resin film 1 is not particularly limited, but various plastic films having transparency are used. For example, the materials include polyester resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, polycycloolefin resin, (meth) acrylic resin, poly Examples thereof include a vinyl chloride resin, a polyvinylidene chloride resin, a polystyrene resin, a polyvinyl alcohol resin, a polyarylate resin, and a polyphenylene sulfide resin. Of these, polyester resins, polycarbonate resins, and polyolefin resins are particularly preferable.

  Although the thickness of the transparent resin film 1 is not particularly limited, it may be in the range of 5 μm to 200 μm, may be in the range of 20 μm to 130 μm, and may be in the range of 40 μm to 130 μm. . In general, the thicker the transparent resin film 1, the higher the hygroscopicity and the easier the expansion, but by adopting the following specific cured resin layer, the transparent conductive film of the transparent conductive film can be used even if the transparent resin film has a thickness in the above range. Cracks can be prevented and the desired electrical characteristics can be exhibited.

  The transparent resin film 1 is subjected to etching or undercoating treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc. on the surface in advance, and the cured resin layer 2 provided thereon You may make it improve the adhesiveness with respect to the transparent resin film 1. FIG. Further, before providing the cured resin layer 2, dust may be removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like, if necessary.

(Cured resin layer)
The cured resin layer 2 is a cured product film obtained by curing a resin composition containing an epoxy resin having a weight average molecular weight of 1500 or more (hereinafter also referred to as “high molecular weight epoxy resin” for convenience). The high molecular weight epoxy resin is preferably the main component of the resin composition. The main component means a component having the maximum content among the components contained in the resin composition, and the content is preferably 20% by weight or more, and 40% by weight or more based on the total amount of the resin composition. More preferred.

  As the high molecular weight epoxy resin, those generally used can be used, and one or more epoxy groups such as a glycidyl group, an alicyclic epoxy group, and an aliphatic epoxy group are preferably included in the molecule. Can use an epoxy group-containing compound having two or more. Specifically, for example, epichlorohydrin-bisphenol A type epoxy resin, epichlorohydrin-bisphenol F type epoxy resin, flame retardant epoxy resin such as glycidyl ether of tetrabromobisphenol A, novolac type epoxy resin, phenol novolac type epoxy resin, water Bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, glycidyl ether type epoxy resin of bisphenol A propylene oxide adduct, p-oxybenzoic acid-glycidyl ether ester type epoxy resin, III-aminophenol type epoxy resin, diamino Diphenylmethane epoxy resin, various alicyclic epoxy resins, N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine, triglycidyl isocyanur Epoxy resins such as glycidyl ethers of polyhydric alcohols such as silicate, polyalkylene glycol diglycidyl ether, glycerin, etc., epoxidized products of unsaturated polymers such as hydantoin type epoxy resins, polysiloxanes having epoxy groups, petroleum resins, etc. An epoxy resin having a weight average molecular weight of 1500 or more is exemplified. A high molecular weight epoxy resin may be used independently and may use 2 or more types together.

  Among them, as the high molecular weight epoxy resin, a hydrogenated bisphenol A type epoxy resin or a hydrogenated bisphenol F type epoxy resin having a weight average molecular weight of 1500 or more is preferable from the viewpoint of the strength, flexibility, and weather resistance of the resulting cured film. .

  Along with the high molecular weight epoxy resin, an epoxy resin having a weight average molecular weight of less than 1500 (hereinafter, also referred to as “low molecular weight epoxy resin” for convenience) among the above listed epoxy resins can be used. As the low molecular weight epoxy resin, an alicyclic epoxy resin is preferable. As the alicyclic epoxy resin, known ones can be suitably used. For example, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, ε-caprolactone-modified 3 ′, 4′-epoxy Cyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexane-1-carboxylate allyl, hydrogenated bisphenol A type epoxy resin having a weight average molecular weight of less than 1500, etc. Is mentioned. A low molecular weight epoxy resin may be used independently and may use 2 or more types together.

  The high molecular weight epoxy resin may have a weight average molecular weight of 1500 or more, preferably 1700 or more, and more preferably 1800 or more. The upper limit of the weight average molecular weight is preferably 5000, more preferably 2000, from the viewpoint of suppressing embrittlement due to excessive curing of the resulting cured resin layer. By setting the weight average molecular weight of the epoxy resin within the above range, a cured resin layer having high crystallinity and excellent film strength can be formed.

  In addition, in this specification, a weight average molecular weight is the value calculated by GPC (gel permeation chromatography, HLC-8320GPC made from TOSOH), and polystyrene conversion. The measurement conditions are as follows. Column: SHODEX GPC KF-802.5 / GPC KF-G, column size: 6.0 mm inner diameter × 150 mm, solvent: tetrahydrofuran (THF), solution concentration: 0.05 wt%, flow rate: 1 mL / min, detector: differential Refractometer (RI), column temperature: 40 ° C., injection amount: 2 mL

  The high molecular weight epoxy resin is preferably a rubber-modified epoxy resin. Thereby, toughness and impact resistance can be suitably imparted to the cured resin layer. The rubber component for modifying the epoxy resin is not particularly limited. Butadiene rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, butyl rubber, nitrile rubber, natural rubber, isoprene rubber, chloroprene rubber, ethylene-propylene rubber, urethane rubber, silicone Examples thereof include rubber, fluororubber, ethylene-vinyl acetate rubber, epichlorohydrin rubber and the like. Of these, butadiene rubber is preferable in terms of toughness and chemical resistance. The rubber-modified epoxy resin may be used alone or in combination of two or more.

  A conventionally known method can be adopted as a method for preparing the rubber-modified epoxy resin. For example, a carboxyl group is introduced into the terminal of the polymer main chain of the rubber component, and this carboxyl group and the epoxy group of the epoxy resin are converted into a phosphorus catalyst. And a method of reacting in the presence of a catalyst such as an amine catalyst.

  The resin composition preferably contains a curing accelerator. Thereby, the hardening reaction of an epoxy resin can be advanced rapidly and fully, and a hardened | cured material film | membrane with high film | membrane intensity | strength can be formed. The curing accelerator is not particularly limited, and examples thereof include organic metal salts of organic acids such as octanoic acid, stearic acid, acetylacetonate, naphthenic acid and salicylic acid, such as zinc, copper, iron and antimony; metal chelates and the like. . Especially, it is preferable that a hardening accelerator contains antimony. The antimony-containing curing accelerator can rapidly and sufficiently advance the curing reaction of the resin composition and can efficiently form a stronger cured product film. In addition, a hardening accelerator can be used individually or in combination of 2 or more types.

  Although content of a hardening accelerator is not specifically limited, 0.005-5 weight part is preferable with respect to the whole quantity (100 weight part) of the compound which has an epoxy group contained in a resin composition, More preferably, it is 0. 0.01 to 4 parts by weight, more preferably 0.01 to 1 part by weight. If the content of the curing accelerator is below the lower limit, the curing acceleration effect may be insufficient. On the other hand, when content of a hardening accelerator exceeds the said upper limit, hardened | cured material may color and a hue may deteriorate.

  The gelation time when the mixture of the resin composition and the epoxy resin curing accelerator is heated at 170 ° C. is preferably 50 seconds or shorter, and more preferably 20 seconds or shorter. By setting the gelation time of the resin composition to which the curing accelerator is added to 50 seconds or less, the curing reaction of the resin composition can be rapidly and sufficiently advanced to form a stronger cured product film. . Although the gelation time is preferably short, it is preferably 10 seconds or longer from the viewpoint of the stability and handling properties of the mixture.

  In addition to the epoxy resin, an acrylic resin, a urethane resin, an amide resin, a silicone resin, or the like may be appropriately blended in the resin composition. Furthermore, various additives can also be added to the resin composition. As the additive, for example, a leveling agent, a pigment, a filler, a dispersant, a plasticizer, an ultraviolet absorber, a surfactant, an antioxidant, a thixotropic agent, and the like can be used.

(Physical properties of cured resin layer)
The surface elastic modulus of the cured resin layer may be 4 GPa or more and 12 GPa or less. Furthermore, the surface elastic modulus is preferably 4.5 GPa or more, and more preferably 5 GPa or more. The surface elastic modulus is preferably 10 GPa or less, and more preferably 9 GPa or less. When the surface elastic modulus of the cured resin layer is less than the above lower limit, the film strength of the cured resin layer becomes insufficient, and the heat and moisture resistance of the transparent conductive film may be lowered. On the other hand, if the surface elastic modulus of the cured resin layer exceeds the above upper limit, the flexibility of the cured resin layer is lowered, and whitening or cracking may occur when the transparent conductive film is folded.

  The saturation expansion coefficient of the cured resin layer under an atmosphere of 85 ° C. and 85% humidity is preferably 0.5% or less, and more preferably 0.4% or less. By setting the saturation expansion coefficient of the cured resin layer in such a range, the moisture and heat resistance of the transparent conductive film is increased, and the stability and certainty of the output of electrical characteristics can be improved. In addition, although the said saturation expansion coefficient is so preferable that it is low, it is preferable that it is 0.05% or more from the point of the softness | flexibility of a cured resin layer. The saturation expansion coefficient can be obtained by using a thermomechanical measurement apparatus (TMA) and by putting a film in an atmosphere at a temperature of 85 ° C. and a humidity of 85% and obtaining a dimensional change when the film is saturated.

The cured resin layer 2 is provided between the transparent resin film 1 and the transparent conductive film 3 and does not have a function as a conductor layer. That is, the cured resin layer 2 is provided as a dielectric layer so that it can be insulated between the patterned transparent conductive films 3. Therefore, the cured resin layer 2 usually has a surface resistance of 1 × 10 ⁶ Ω / □ or more, preferably 1 × 10 ⁷ Ω / □ or more, and more preferably 1 × 10 ⁸ Ω / □ or more. There is no particular upper limit on the surface resistance of the cured resin layer 2. Generally, the upper limit of the surface resistance of the cured resin layer 2 is about 1 × 10 ¹³ Ω / □, which is a measurement limit, but may exceed 1 × 10 ¹³ Ω / □.

  The thickness of the cured resin layer 2 is not particularly limited, but is 150 nm or less, preferably about 20 to 100 nm, from the viewpoints of heat and humidity resistance, the effect of preventing oligomer generation from the transparent resin film 1 and optical properties. Yes, more preferably 30 to 50 nm. In addition, when providing two or more cured resin layers 2, the thickness of each layer is about 20-60 nm, Preferably it is 25-55 nm.

  In this embodiment, what has a good appearance as a display element is obtained by having the patterned transparent conductive film 3 and the cured resin layer 2. From this viewpoint, the refractive index of the cured resin layer 2 is preferably such that the difference between the refractive index of the transparent conductive film 3 and the refractive index of the cured resin layer is 0.1 or more. The difference between the refractive index of the transparent conductive film 3 and the refractive index of the cured resin layer is preferably from 0.1 to 0.9, and more preferably from 0.1 to 0.6. In addition, it is preferable that the refractive index of the cured resin layer 2 is 1.3-2.5 normally, Furthermore, 1.38-2.3, Furthermore, it is preferable that it is 1.4-2.3.

  As described above, the transparent conductive film 3 preferably has a refractive index difference of 0.1 or more from the cured resin layer 2. The refractive index of the transparent conductive film 3 is usually about 1.95 to 2.05.

  The method for forming the cured resin layer is not particularly limited, but is preferably by coating. First, a resin composition containing the above components is uniformly dissolved and dispersed in a solvent to prepare a coating solution. The solvent is not particularly limited. For example, aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, acetone, methyl isobutyl ketone and cyclohexanone; diethyl ether, isopropyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene Ether solvents such as glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, anisole, phenetol; ester solvents such as ethyl acetate, butyl acetate, isopropyl acetate, ethylene glycol diacetate; dimethylformamide, diethylformamide, Amide solvents such as N-methylpyrrolidone; methyl cellosolve, Chiruserosorubu, cellosolve-based solvents such as butyl cellosolve; methanol, ethanol, alcohol solvents such as propanol; and the like; dichloromethane, halogenated solvents such as chloroform. These solvents may be used alone or in combination of two or more.

  The solid concentration of the coating solution is preferably 0.5% by weight to 2.5% by weight, more preferably 1.0% by weight to 2.0% by weight, and particularly preferably 1.5% by weight to 1.9% by weight. preferable.

  The cured resin layer is formed by applying the above coating solution on a transparent resin film and curing it. In addition, the coating solution may be performed directly on the transparent resin film 1 or may be performed on an undercoat layer or the like formed on the transparent resin film 1.

  The application method of the coating solution can be appropriately selected according to the state of the coating solution and the painting process. For example, dip coating method, air knife coating method, curtain coating method, roller coating method, wire bar coating method, gravure coating method It can be applied by a die coating method or an extrusion coating method.

  Finally, a cured resin layer can be formed by heat-curing the obtained coating film. As a heating method, heating by a hot air dryer, an infrared dryer, a vacuum dryer, a microwave heating dryer or the like can be employed. As heating temperature, it is 100-200 degreeC, for example, and 120-180 degreeC is preferable. The heating time is, for example, 0.5 to 10 minutes, and preferably 1 to 5 minutes.

(Transparent conductive film)
The constituent material of the transparent conductive film 3 is not particularly limited, and is selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, and tungsten. A metal oxide of at least one metal is used. The metal oxide may further contain a metal atom shown in the above group, if necessary. For example, indium oxide containing tin oxide and tin oxide containing antimony are preferably used.

The thickness of the transparent conductive film 3 is not particularly limited, but it is preferably 10 nm or more in order to obtain a continuous film having good surface resistance of 1 × 10 ³ Ω / □ or less. When the film thickness becomes too thick, the transparency is lowered, and it is preferably 15 to 35 nm, more preferably in the range of 20 to 30 nm. When the thickness is less than 15 nm, the surface electrical resistance increases and it becomes difficult to form a continuous film. Moreover, when it exceeds 35 nm, transparency will fall.

  It does not specifically limit as a formation method of the transparent conductive film 3, A conventionally well-known method is employable. Specifically, for example, a vacuum deposition method, a sputtering method, and an ion plating method can be exemplified. In addition, an appropriate method can be adopted depending on the required film thickness. In addition, after forming the transparent conductive film 3, it can crystallize by giving an annealing process within the range of 100-150 degreeC as needed. For this reason, it is preferable that the transparent resin film 1 has a heat resistance of 100 ° C. or higher, more preferably 150 ° C. or higher. In the present embodiment, the transparent conductive film 3 is patterned by etching. Since the etching may be difficult when the transparent conductive film 3 is crystallized, the annealing treatment of the transparent conductive film 3 is preferably performed after the transparent conductive film 3 is patterned. Furthermore, when the cured resin layer 2 is etched, it is preferable that the transparent conductive film 3 is annealed after the cured resin layer 2 is etched.

  The transparent conductive film 3 may be patterned on the cured resin layer 2. The patterning can form various patterns according to the application to which the transparent conductive film is applied. In addition, although the pattern part and the non-pattern part are formed by patterning the transparent conductive film 3, examples of the shape of the pattern part include a stripe shape. FIG. 5 relates to a top view of the transparent conductive film of the present embodiment, and is an example in the case where the transparent conductive film 3 is formed in a stripe shape, and the pattern portion a and the non-pattern portion b of the transparent conductive film 3 are in a stripe shape. Is formed. In FIG. 5, the width of the pattern portion a is larger than the width of the non-pattern portion b, but is not limited to this range.

  The rate of change of the surface resistance value of the transparent conductive film before and after the patterned transparent conductive film is placed in an atmosphere of 85 ° C. and 85% humidity for 240 hours is preferably 1.5 or less, and 1.3 or less. It is more preferable that As a result, even when the transparent conductive film is placed in a harsh environment, the desired electrical characteristics can be exhibited, and thereby various applications can be developed.

(Other configurations)
A hard coat layer, an easy-adhesion layer, an anti-blocking layer, and the like may be provided on the surface of the transparent resin film 1 opposite to the surface on which the transparent conductive film 3 is formed, as necessary.

(Method for producing transparent conductive film)
The manufacturing method of the transparent conductive film of this embodiment will not be restrict | limited especially if the cured resin layer and the transparent conductive film have the said structure on the single side | surface or both surfaces of a transparent resin film. For example, according to usual, after preparing a transparent conductive film having a transparent conductive film on at least one cured resin layer from the transparent resin film side on one side or both sides of the transparent resin film, It can be manufactured by etching and patterning. In the etching, the transparent conductive film is covered with a mask for forming a pattern, and the transparent conductive film is etched with an etching solution.

  As the transparent conductive film, indium oxide containing tin oxide and tin oxide containing antimony are suitably used, so that an acid is suitably used as the etching solution. Examples of the acid include inorganic acids such as hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid, phosphoric acid, organic acids such as acetic acid, mixtures thereof, and aqueous solutions thereof.

  In addition, a transparent pressure-sensitive adhesive layer is disposed on one side of the transparent conductive film of the present embodiment so that the patterned transparent conductive film 3 is disposed on one side of the transparent conductive film on which the transparent substrate 5 is bonded. The transparent substrate 5 can be bonded via 4. 4 shows a transparent conductive film having a structure in which a transparent substrate 5 is bonded to a transparent resin film 1 (a surface on which a transparent conductive film 3 is not provided) of the transparent conductive film of FIG. It is a film. The transparent substrate 5 may have a composite structure in which at least two transparent substrate films are bonded together with a transparent adhesive layer. In addition, patterning of the said transparent conductive film 3 can also be given with respect to the transparent conductive film made into this structure.

  In general, the thickness of the transparent substrate 5 is preferably 90 to 300 μm, and more preferably 100 to 250 μm. Moreover, when forming with the several base film which forms the transparent base | substrate 5, the thickness of each base | substrate film is 10-200 micrometers, Furthermore, it is 20-150 micrometers, The transparent base | substrate 5 including the transparent adhesive layer in these base | substrate films The total thickness is controlled so as to fall within the above range. As a base film, the thing similar to the above-mentioned transparent resin film 1 is mentioned.

  The transparent conductive film (for example, the transparent resin film 1) and the transparent substrate 5 are bonded together by providing the pressure-sensitive adhesive layer 4 on the transparent substrate 5 side and bonding the transparent resin film 1 to the adhesive layer 4. Alternatively, conversely, the pressure-sensitive adhesive layer 4 may be provided on the transparent resin film 1 side, and the transparent substrate 5 may be bonded thereto. The latter method is more advantageous in terms of productivity because the pressure-sensitive adhesive layer 4 can be continuously formed with the transparent resin film 1 in a roll shape. The transparent substrate 5 can also be laminated on the transparent resin film 1 by sequentially bonding a plurality of substrate films with an adhesive layer. In addition, the thing similar to the following transparent adhesive layer 4 can be used for the transparent adhesive layer used for lamination | stacking of a base film. In addition, when the transparent conductive films are bonded to each other, the transparent conductive films can be bonded to each other by appropriately selecting a laminated surface of the transparent conductive films on which the pressure-sensitive adhesive layer 4 is stacked.

  The pressure-sensitive adhesive layer 4 can be used without particular limitation as long as it has transparency. Specifically, for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy systems, fluorine systems, natural rubbers, rubbers such as synthetic rubbers, etc. Those having the above polymer as a base polymer can be appropriately selected and used. In particular, an acrylic pressure-sensitive adhesive is preferably used from the viewpoint that it is excellent in optical transparency, exhibits adhesive properties such as appropriate wettability, cohesiveness and adhesiveness, and is excellent in weather resistance and heat resistance.

  Depending on the type of the pressure-sensitive adhesive that is a constituent material of the pressure-sensitive adhesive layer 4, there is one that can improve the anchoring force by using an appropriate pressure-sensitive adhesive primer. Accordingly, when such an adhesive is used, it is preferable to use an adhesive primer.

  The adhesive undercoat is not particularly limited as long as it is a layer that can improve the anchoring force of the adhesive. Specifically, for example, a silane coupling agent having a reactive functional group such as amino group, vinyl group, epoxy group, mercapto group, chloro group and hydrolyzable alkoxysilyl group in the same molecule, the same molecule Titanate coupling agent having hydrolyzable hydrophilic group and organic functional group containing titanium in the inside, and aluminum having hydrolyzable hydrophilic group and organic functional group containing aluminum in the same molecule A resin having an organic reactive group such as a so-called coupling agent such as an nate coupling agent, an epoxy resin, an isocyanate resin, a urethane resin, or an ester urethane resin can be used. From the viewpoint of easy industrial handling, a layer containing a silane coupling agent is particularly preferred.

  The pressure-sensitive adhesive layer 4 can contain a cross-linking agent according to the base polymer. Further, the pressure-sensitive adhesive layer 4 may be made of, for example, a natural or synthetic resin, a glass fiber or glass bead, a filler made of metal powder or other inorganic powder, a pigment, a colorant, an antioxidant, or the like. These appropriate additives can also be blended. Moreover, it can also be set as the adhesive layer 4 to which light diffusivity was provided by containing transparent fine particles.

  The transparent fine particles include, for example, conductive inorganic fine particles such as silica, calcium oxide, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle size of 0.5 to 20 μm. Alternatively, one or two or more suitable ones such as crosslinked or uncrosslinked organic fine particles made of a suitable polymer such as polymethyl methacrylate and polyurethane can be used.

  The pressure-sensitive adhesive layer 4 is usually used as a pressure-sensitive adhesive solution having a solid content concentration of about 10 to 50% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent. As the solvent, an organic solvent such as toluene or ethyl acetate or an adhesive such as water can be appropriately selected and used.

  Moreover, since the cushioning effect cannot be expected when the thickness of the pressure-sensitive adhesive layer 4 is less than 1 μm, it is difficult to improve the scratch resistance of the transparent conductive film 3, pen input durability and surface pressure durability for touch panels. Tend to be. On the other hand, if it is too thick, the transparency is impaired, and it is difficult to obtain good results in terms of the formation of the pressure-sensitive adhesive layer 4, the bonding workability of the transparent substrate 5, and the cost.

  The transparent substrate 5 bonded via the pressure-sensitive adhesive layer 4 gives good mechanical strength to the transparent resin film 1 and, in addition to pen input durability and surface pressure durability, in particular, curl. It contributes to the prevention of such occurrences.

  When the pressure-sensitive adhesive layer 4 is transferred using the release film S, as such a release film S, for example, a transition prevention layer and / or a release layer is provided on the surface of the polyester film that adheres to at least the pressure-sensitive adhesive layer 4. It is preferable to use a laminated polyester film or the like.

  The total thickness of the release film S is preferably 30 μm or more, and more preferably in the range of 60 to 100 μm. This is to suppress deformation (dentation) of the pressure-sensitive adhesive layer 4 that is assumed to be generated by foreign matter or the like that has entered between the rolls when the pressure-sensitive adhesive layer 4 is formed and stored in a roll state.

(Touch panel)
The transparent conductive film of the present embodiment can be suitably applied to, for example, an optical method, an ultrasonic method, a capacitance method, a resistance film method, or the like. In particular, it is suitable for a capacitive touch panel. In addition, the transparent conductive film of the present embodiment includes, for example, an electrophoresis method, a twist ball method, a thermal rewritable method, an optical writing liquid crystal method, a polymer dispersed liquid crystal method, a guest / host liquid crystal method, a toner display method, and a chromism. It can be suitably used for flexible display elements such as a method and an electric field deposition method.

Second Embodiment
In the first embodiment, one cured resin layer is formed, whereas in the present embodiment, two layers are provided. FIG. 2 shows a case where there are two cured resin layers 2. In FIG. 2, the cured resin layers 21 and 22 are provided in this order from the transparent resin film 1 side. FIG. 2 shows a case where the cured resin layers 21 and 22 are provided in the non-pattern part b. The cured resin layer 22 above the first layer may be patterned or may not be patterned.

In addition to the material for forming the cured resin layer in the first embodiment, an inorganic material can be suitably used in the present embodiment. For example, NaF (1.3), Na ₃ AlF ₆ (1.35), LiF (1.36), MgF ₂ (1.38), CaF ₂ (1.4), BaF ₂ (1. 3), inorganic substances such as SiO ₂ (1.46), LaF ₃ (1.55), CeF ₃ (1.63), Al ₂ O ₃ (1.63) Is the refractive index of Of these, SiO ₂ , MgF ₂ , A1 ₂ O _{3 and the} like are preferably used. In particular, SiO ₂ is suitable. In addition to the above, a composite oxide containing about 10 to 40 parts by weight of cerium oxide and about 0 to 20 parts by weight of tin oxide with respect to indium oxide can be used.

The cured resin layer formed of an inorganic material can be formed as a dry process such as a vacuum deposition method, a sputtering method, or an ion plating method, or by a wet method (coating method). As the inorganic material forming the cured resin layer, SiO ₂ is preferable as described above. In the wet method, a SiO ₂ film can be formed by applying silica sol or the like.

  In this embodiment, as a material for forming the cured resin layers 21 and 22, the resin in the first embodiment, the inorganic material, and the like may be used in appropriate combination.

<Other embodiments>
Although FIG. 2 illustrates the case where the cured resin layer 2 has two layers, the cured resin layer 2 may have three or more layers. Even when the cured resin layer 2 has three or more layers, the non-pattern part b has at least the first cured resin layer 21 from the transparent resin film 1 side. The cured resin layer above the first layer may be patterned or may not be patterned.

  FIG. 3 is also a cross-sectional view showing an example of the transparent conductive film of the present embodiment. In FIG. 3, the description is made with the same configuration as that of FIG. 1, but naturally, the same configuration as that described with reference to FIG. The transparent conductive film of FIG. 3 is a case where it has the transparent conductive film 3 patterned on both surfaces of the transparent resin film 1 through the cured resin layer 2. In addition, although the transparent conductive film of FIG. 3 has the transparent conductive film 3 patterned on both sides, only one side may be patterned. Further, in the transparent conductive film of FIG. 3, the pattern part a and the non-pattern part b of the patterned transparent conductive film 3 on both sides coincide with each other. Can be appropriately patterned on both sides. The same applies to the other drawings.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to a following example, unless the summary is exceeded. In each example, both parts and% are based on weight.

Example 1
(Formation of cured resin layer)
10 parts of Adekafilterra BUR-12A mainly composed of rubber-modified epoxy resin (weight average molecular weight of epoxy resin skeleton part: 2000) and 0.001 part of Adekafilterra BUR-12B which is an antimony curing accelerator Then, 90 parts of methyl isobutyl ketone was added to the mixture to prepare a coating solution. The gelation time when the mixture was heated at 170 ° C. was 10 seconds. The coating solution is applied to one surface of a transparent resin film made of a polyethylene terephthalate film (hereinafter referred to as PET film) having a thickness of 50 μm, and the coating film is dried (at 195 ° C. for 1 minute), whereby the thickness is 30 nm. A cured resin layer was formed.

  The gelation time of the mixture was measured according to “JIS C 6521 5.7 Curing time” except that the amount of the mixture was 2 g and the specified temperature was set to 170 ° C. That is, 2 g of the mixture was placed on a hot plate adjusted to 170 ° C., and time measurement was started. Immediately the contact circle motion was repeated with a spatula and the time until gelation was measured. During contact circle movement, the mixture should be within a range of 25 mm in diameter, and spatula should not be lifted while the viscosity of the mixture is low. This up-and-down movement was repeated until the time expired. The curing time was from when the mixture was placed on the hot plate until when the thread was broken when the spatula was lifted. The contact circle motion was set to a speed of about 1 second per rotation. The measurement was repeated three times, and the average value was taken as the curing time (gelation time).

(Formation of transparent conductive film)
Next, the reactivity using a sintered body material of 90 wt% indium oxide and 10 wt% tin oxide in an atmosphere of 0.4 Pa composed of 98% argon gas and 2% oxygen gas on the cured resin layer. An ITO film with a thickness of 20 nm (light refractive index of 2.00) was formed by sputtering to obtain a transparent conductive film.

(Patterning of ITO film)
After the cellophane tape was pasted onto the ITO film so as to be patterned in stripes, this was immersed in 50 wt. C., 10 wt% hydrochloric acid (hydrogen chloride aqueous solution) for 10 minutes to etch the ITO film. went. The obtained ITO film had a pattern width of 6 mm and a pattern pitch of 6 mm. Thereafter, the cellophane tape was removed, and the ITO film was patterned.

(Crystalization of ITO film)
After etching the ITO film, heat treatment was performed at 140 ° C. for 90 minutes to crystallize the ITO film, thereby producing a transparent conductive film in which the ITO film was patterned.

Example 2
In the formation of the cured resin layer, 10 parts of Adekafilterra CRX-11 mainly composed of rubber-modified epoxy resin (weight average molecular weight of epoxy resin skeleton part: 2000), Adekafilterra BUR-, which is an antimony-based curing accelerator, A transparent conductive film was produced in the same manner as in Example 1 except that a mixture obtained by mixing 0.001 part of 12B was used. The gel time of this mixture was 32 seconds.

Example 3
In the formation of the cured resin layer, 10 parts of Adekafilterra CRX-10 mainly composed of rubber-modified epoxy resin (weight average molecular weight of epoxy resin skeleton part: 2000), Adekafilterra BU-, which is an antimony-based curing accelerator A transparent conductive film was produced in the same manner as in Example 1 except that a mixture obtained by mixing 0.001 part of 12B was used. The gel time of this mixture was 28 seconds.

<< Comparative Example 1 >>
In the formation of the cured resin layer, 10 parts of Adekafilterra CRX-6 mainly composed of acrylic-modified epoxy resin (weight average molecular weight of epoxy resin skeleton part: 500), 0.5% of zinc-based curing accelerator (Adeka Stub) A transparent conductive film was produced in the same manner as in Example 1 except that a partially mixed mixture was used. The gel time of this mixture was 240 seconds.

<< Comparative Example 2 >>
In the formation of the cured resin layer, 10 parts of Adekafilterra CRX-5 mainly composed of an acrylic-modified epoxy resin (weight average molecular weight of epoxy resin skeleton part: 500) and 0.5 of a zinc-based curing accelerator (Adeka Stub) A transparent conductive film was produced in the same manner as in Example 1 except that a partially mixed mixture was used. The gel time of this mixture was 99 seconds.

<< Comparative Example 3 >>
In the formation of the cured resin layer, 10 parts of Adekafilterra CRX-4 whose main component is an unmodified epoxy resin (weight average molecular weight: 500) and 0.5 part of a zinc-based curing accelerator (Adeka Stub) A transparent conductive film was produced in the same manner as in Example 1 except that the mixed mixture was used. The gel time of this mixture was 102 seconds.

<< Comparative Example 4 >>
In the formation of the cured resin layer, 10 parts of Adekafilterra CRX-3 whose main component is an unmodified epoxy resin (weight average molecular weight: 500), and 0.5 part of a zinc-based curing accelerator (Adeka Stub) A transparent conductive film was produced in the same manner as in Example 1 except that the mixed mixture was used. The gel time of this mixture was 67 seconds.

  The following evaluation was performed about the transparent conductive film (sample) of an Example and a comparative example. The results are shown in Table 1 or the text.

(1) Thickness of each layer About what has thickness of 1 micrometer or more, such as a transparent resin film, it measured with the micro gauge type thickness meter by Mitutoyo. The thickness of the cured resin layer, the ITO film, etc. was calculated based on the waveform from the interference spectrum using MCPD2000 (trade name) which is an instantaneous multi-photometry system manufactured by Otsuka Electronics Co., Ltd.

(2) Surface Elastic Modulus of Cured Resin Layer The transparent conductive film was immersed in hydrochloric acid (aqueous hydrogen chloride) at 50 ° C. and 10% by weight for 10 minutes to remove the ITO film, and the cured resin layer was exposed. The surface elastic modulus of this cured resin layer was measured by the following procedure. Hysitron Inc. Measurement was carried out at a temperature of 25 ° C. and an indentation amount of 20 nm by a single indentation method using a manufactured product, Tribodenter device, indenter used: Berkovich (triangular pyramid type).

(3) Moisture and heat resistance characteristics The surface resistance value (Ω / □) of the obtained crystalline transparent conductive layer was measured by a four-terminal method according to JIS K7194 (1994), and this was determined as the initial surface resistance value R0. did. Next, the surface resistance value R240 was measured after leaving for 240 hours in a thermo-hygrostat (manufactured by Espec Corp., LHL-113) set to 85 ° C. and 85% RH. R240 / R0 was calculated | required from these as resistance change rate. The case where the resistance change rate was 1.5 or less was evaluated as “◯”, and the case where the resistance change rate exceeded 1.5 was evaluated as “×”.

(4) Solvent resistance The prepared transparent conductive film was immersed in isopropanol at 25 ° C. for 10 minutes, then taken out, washed with pure water, and dried, and the surface of the cured resin layer was visually observed. The case where there was no change in appearance was evaluated as “◯”, and the case where there was a change in appearance such as roughening or discoloration was evaluated as “x”.

(5) Alkali durability The produced transparent conductive film was immersed in an alkali solution (5 wt%) at 50 ° C. for 5 minutes, taken out, washed with pure water, and dried, and the surface of the cured resin layer was visually observed. . The case where there was no change in appearance was evaluated as “◯”, and the case where there was a change in appearance such as roughening or discoloration was evaluated as “x”.

(6) Existence of oligomer exudation The produced transparent conductive film was heat-treated at 160 ° C. for 2 hours, and the oligomer exudation from the cured resin layer at that time was visually confirmed. Evaluation was made according to the following criteria.
○: No oligomer exudation was confirmed.
Δ: Slight oligomer exudation was confirmed.
X: Exudation of the oligomer was extensive.

  From Table 1, it is recognized that the transparent conductive films of the examples have excellent heat and moisture resistance and can withstand use under high temperature and high humidity conditions.

DESCRIPTION OF SYMBOLS 1 Transparent resin film 2 Cured resin layer 3 Transparent electrically conductive film 4 Adhesive layer 5 Transparent base | substrate 6 Hard coat layer a Pattern part b Non-pattern part

Claims (7)

A transparent conductive film having a cured resin layer and a transparent conductive film in this order on the transparent resin film,
The cured resin layer is a cured product film obtained by curing a resin composition containing an epoxy resin having a weight average molecular weight of 1500 or more,
The thickness of the cured resin layer is 150 nm or less,
The transparent conductive film whose surface elastic modulus of the said cured resin layer is 4 GPa or more and 12 GPa or less.   The transparent conductive film according to claim 1, wherein the gelation time when the mixture of the resin composition and the epoxy resin curing accelerator is heated at 170 ° C. is 50 seconds or less.   The transparent conductive film according to claim 2, wherein the curing accelerator contains antimony.   The transparent conductive film according to claim 1, wherein the epoxy resin is a rubber-modified epoxy resin.   The transparent conductive film according to any one of claims 1 to 4, wherein the cured resin layer has a saturation expansion coefficient of 0.5% or less in an atmosphere at a temperature of 85 ° C and a humidity of 85%. The transparent conductive film is patterned,
The transparent conductive property according to any one of claims 1 to 5, wherein a rate of change of the surface resistance value is 1.5 or less before and after the transparent conductive film is placed in an atmosphere at a temperature of 85 ° C and a humidity of 85% for 240 hours. the film. The touch panel containing the transparent conductive film of any one of Claims 1-6.

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