TW201712512A - Transparent conductive film and touch panel comprising same - Google Patents

Abstract

The purpose of the present invention is to provide: a transparent conductive film which has a sufficient material strength by using, as the base, a polyester having a low retardation, and which achieves sufficient iridescent irregularity suppression effect, while being produced with high productivity from low-cost starting materials; and a touch panel which comprises this transparent conductive film. The present invention is a transparent conductive film which comprises a transparent resin film and a transparent conductive film, and which is characterized in that the transparent resin film is a biaxially stretched polyester resin film having an in-plane retardation of 150 nm or less and a retardation in the thickness direction of 1,000 nm or less.

Description

Transparent conductive film and touch panel containing the same

The present invention relates to a transparent conductive film having a transparent resin film and a transparent conductive film, and a touch panel including the transparent conductive film.

Background Art In recent years, with the spread of tablets, smart phones, and PCs with touch panels, the opportunities for operating electronic devices outdoors have increased dramatically. When viewing the display outdoors, the situation of wearing polarized sunglasses is also increased. In this case, if a transparent conductive film using a polyethylene terephthalate (PET) film is used, there is a face of the PET film itself. The internal phase difference (generally 1000~2000nm) produces rainbow lines, which greatly reduces the visibility of the display.

Therefore, development of a transparent conductive film using a substrate having a small retardation value (a cyclic olefin resin or the like) has been developed. However, cyclic olefin resins and the like have disadvantages such as weak material strength and high price of the material itself, so studies have been conducted on materials having low cost and high strength.

For the above reasons, Patent Document 1 proposes a transparent conductive film having a transparent resin film formed of an extended polyester or the like having an in-plane retardation of 4000 nm or more as a base material. With this transparent conductive film, rainbow stripes are not generated even when viewed by polarized sunglasses.

Advance Technical Literature Patent Literature Patent Document 1: Japanese Patent Laid-Open Publication No. 2004-214069

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, such a polyester film or the like having a large in-plane retardation value has a weak material strength for uniaxial stretching, and a thick film for increasing a phase difference, so that material cost increases. Disadvantages such as poor productivity, as a general material, there are problems that are difficult to deal with.

Accordingly, an object of the present invention is to provide a transparent conductive film which has sufficient material strength by using a polyester having a low phase difference as a substrate, is inexpensive in material cost, is excellent in productivity, and can sufficiently suppress the effect of rainbow lines. A touch panel containing it.

The present inventors have intensively studied to solve the above problems, and as a result, found that a biaxially stretched polyester resin film is used in a specific range by using an in-plane phase difference value and a thickness direction retardation value. The above object can be attained as a substrate, and the present invention has been completed.

In other words, the transparent conductive film of the present invention has a transparent resin film and a transparent conductive film, and the transparent resin film is a biaxially stretched polyester resin film having an in-plane retardation value of 150 nm or less and a thickness direction. The phase difference is 1000 nm or less. Further, various physical properties in the present invention are values measured by the methods used in the examples and the like.

In general, the biaxially stretched polyester resin film has sufficient material strength and is inexpensive, but the in-plane retardation is about 1000 to 2000 nm, and if it is used for a substrate of a transparent conductive film, wavelength is utilized. Dispersion has insufficient effect of polarizing non-polarization, resulting in rainbow lines. On the other hand, as shown in the present invention, when a polyester resin film having an in-plane retardation value of 150 nm or less and a thickness direction retardation of 1000 nm or less is used, as shown by the results of the examples, a sufficient rainbow pattern can be obtained. The suppression effect.

The detailed reasons are not clear, but they are considered as follows. In other words, when a polyester resin film having an in-plane retardation of 150 nm or less is used, it is effective to polarize a linearly polarized circle (including elliptically polarized light), and the effect is that the thickness difference in the thickness direction is 1000 nm. In the following, it is possible to suppress the change in the color tone from the viewing direction, so that a sufficient rainbow pattern suppressing effect can be obtained.

As a result, when the transparent conductive film of the present invention is used, by using a polyester having a low phase difference as a substrate, it is possible to provide a material having sufficient material strength, a low material cost, good productivity, and sufficient suppression of rainbow stripes. The effect of a transparent conductive film.

In the above, it is preferable that at least one optical adjustment layer is provided between the transparent resin film and the transparent conductive film. Since the refractive index can be controlled by the optical adjustment layer, the difference in reflectance between the pattern forming portion and the pattern opening portion when the transparent conductive film is patterned can be reduced, and the transparent conductive film pattern is less likely to be seen, and is displayed in a display device such as a touch panel. Visual recognition has become good.

Further, the thickness of the transparent resin film is preferably 5 to 50 μm. When the thickness is in this range, a biaxially stretched polyester resin film having an in-plane retardation of 150 nm or less and a thickness direction retardation of 1000 nm or less can be easily produced at low cost.

Further, the transparent resin film is preferably an elongated body or a rectangular monolith, and the alignment axis has an angle of 10 to 45 with respect to the long side or the short side. The transparent conductive film is often laminated on a rectangular optical display device such as a liquid crystal element, and the light from the optical display device is mostly polarized in parallel or perpendicular to the long side thereof. Therefore, in the present invention, by having the alignment axis at an angle of 10 to 45° with respect to the long side or the short side, it is easy to arrange the slow phase axis at an angle of 10 to 45° with respect to the polarized light, by the transparent resin film. The effect of polarizing the polarizing circle becomes large, and the effect of suppressing the rainbow pattern can be easily obtained.

It is preferable that at least one surface of the transparent resin film has a hardened resin layer. The hardened resin layer functions as a hard coat layer for preventing injury or the like during transportation, and functions as an anti-adhesion layer by causing irregularities on the surface.

In the surface of the transparent resin film on which the transparent conductive film is not provided, it is preferable to have an adhesive layer and a protective film in this order. The transparent conductive film of the present invention can be made into an adhesive type by improving the handleability of the protective film and forming the protective film as a separator.

On the other hand, the touch panel of the present invention is characterized in that it is obtained by using the transparent conductive film of the present invention. By using the transparent conductive film of the present invention, it is possible to provide a touch panel having sufficient material strength, low material cost, good productivity, and sufficient effect of suppressing rainbow lines.

In the form of the invention, the laminated structure of the transparent conductive film is as shown in FIGS. 1 to 3, and the transparent conductive film 20 of the present invention has the transparent resin film 4 and the transparent conductive film 6, and is formed in the transparent resin film 4 and Preferably, at least one optical adjustment layer 7 is provided between the transparent conductive films 6. Further, as shown in FIGS. 2 to 3, at least one surface of the transparent resin film 4 may have a cured resin layer such as the anti-adhesion layer 3 or the hard coat layer 5. Further, as shown in FIGS. 4 to 6, the transparent conductive film 20 may be provided on the side of the transparent resin film 4 on which the transparent conductive film 6 is not provided, and the adhesive layer 2 and the protective film 1 are sequentially provided. The agent layer 2 and the protective film 1 constitute a carrier film 10.

(Transparent Resin Film) As the transparent resin film, a biaxially stretched polyester resin film can be used. The term "biaxially extending" means that the film is stretched in at least two directions, and the two directions can be simultaneously or sequentially performed.

The polyester-based resin may, for example, be a polyester-based resin selected from the group consisting of polyesters, modified polyesters, and the like. As the polyester resin, for example, a condensation polymerization of a carboxylic acid component and a polyvalent ester component can be used.

Examples of the carboxylic acid component include an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, and an alicyclic dicarboxylic acid. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, benzylmalonic acid, 1,4-naphthalene dicarboxylic acid, dibenzoic acid, 4,4'-oxybenzoic acid, and 2 , 5-naphthalenedicarboxylic acid. Examples of the aliphatic dicarboxylic acid include malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, trimethyl adipate, pimelic acid, and 2,2-dimethyl A glutaric acid, azelaic acid, azelaic acid, fumaric acid, maleic acid, itaconic acid, thiodipropionic acid, diglycolic acid. Examples of the alicyclic dicarboxylic acid include 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, and 1,4-ring. Hexanedicarboxylic acid, 2,5-norbornane dicarboxylic acid, adamantane dicarboxylic acid. The carboxylic acid component may be a derivative such as an ester, a chloride or an acid anhydride, and includes, for example, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 2,6-naphthalene dicarboxylate, and dimethyl isophthalate. , dimethyl terephthalate and diphenyl terephthalate. The carboxylic acid component may be used singly or in combination of two or more.

As a polyhydric alcohol, a diol is mentioned typically. Examples of the glycol include an aliphatic diol, an alicyclic diol, and an aromatic diol. Examples of the aliphatic diol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, and 2,4-dimethyl-2-ethylhexane. -1,3-diol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2 -isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1, 5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol. Examples of the alicyclic diol include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroethylene glycol, and tricyclic guanidine. Dimethanol, adamantanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Examples of the aromatic diol include 4,4'-thiodiphenol, 4,4'-methylene diphenol, 4,4'-(2-norbornyl) diphenol, and 4,4'. -dihydroxybisphenol, o-, m- and hydroquinone, 4,4'-isopropylidene phenol, 4,4'-isopropylidene bis(2,6-dichlorophenol) 2,5-naphthalene Glycol and terephthalic acid. The polyol component may be used singly or in combination of two or more.

Preferred examples of the carboxylic acid component include terephthalic acid, isophthalic acid, and 2,5-naphthalene dicarboxylic acid. Preferred examples of the polyol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexane. Methanol.

The structure of the polyester is determined according to the combination of the monomers as described above. Therefore, preferred examples of the polyester-based resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polypair. Copolymers, blends and modified bodies of cyclohexyl phthalate and the like.

By applying the polyester resin as described above and including the obliquely extending manufacturing method, a transparent resin film having a preferable in-plane retardation and the direction of the alignment axis and having more excellent axial precision can be obtained.

In the present invention, the polyester resin may be a modified PET containing a repeating unit derived from cyclohexanedimethanol. In this case, the ratio of the cyclohexanedimethanol in the polyol component is preferably more than 0 mol% and 10 mol% or less, more preferably more than 0 mol% and 3 mol% or less. Further, the polyester resin may be a modified PET containing a repeating unit derived from isophthalic acid. In this case, the ratio of the phthalic acid in the carboxylic acid component is preferably more than 0 mol% and 20 mol% or less, more preferably more than 0 mol% and 10 mol% or less. Further, of course, these embodiments can be combined.

The transparent resin film is produced in the form of a strip-shaped film (long strip) which is biaxially stretched. In the present specification, the term "long strip" means an elongated shape having a ratio of length to width of 10 or more. The ratio of the length of the transparent resin film to the width is preferably 30 or more, more preferably 100 or more. In one embodiment, the transparent resin film is an elongated body wound in a roll shape, and in another embodiment, the transparent resin film is a rectangular single piece.

The transparent resin film preferably has an alignment axis having an angle of 10 to 45° with respect to the long side or the short side, more preferably an angle of 20 to 45°, and most preferably an angle of 30 to 45°. Further, in the transparent conductive film of the present invention, the alignment axis of the transparent resin film is preferably disposed at an angle of 10 to 80° with respect to the direction of the linearly polarized light emitted from the display device, preferably 20 to 70°. The angle configuration is preferably configured at an angle of 30 to 60 degrees.

Therefore, the direction of the slow axis of the elongated film is in the range of 30° to 60°, preferably 38° to 52°, and more preferably 43 in the entire width direction of the film. The range of °~47° is preferably an angle of about 45° with respect to the longitudinal direction of the slow axis direction. The transparent resin film can obtain a transparent resin film having excellent axial precision and a retardation axis in the oblique direction by applying a manufacturing method including oblique stretching.

The in-plane retardation R0 of the transparent resin film is from 0 to 150 nm, and from the viewpoint of further enhancing the effect of suppressing rainbow stripes, it is preferably from 10 to 130 nm, more preferably from 20 to 110 nm.

Here, the in-plane phase difference R0 is an in-plane phase difference of a film measured by light having a wavelength of 590 nm at 23 ° C. When the thickness of the film is d (nm), R0 is obtained by the formula: R0 = (nx - ny) × d. Here, nx is a refractive index in which the refractive index in the plane becomes the largest (ie, the direction of the slow axis), and ny is the refractive index in the direction orthogonal to the axis of the late phase.

The thickness direction Rth of the transparent resin film is 1000 nm or less, and is preferably from 350 to 950 nm, more preferably from 400 to 900 nm, from the viewpoint of further improving the effect of suppressing rainbow lines and obtaining sufficient strength.

Here, the thickness direction phase difference Rth is a phase difference in the thickness direction of the film measured by light having a wavelength of 590 nm at 23 ° C. When the thickness of the film is d (nm), Rth is obtained by the formula: Rth = (nx - nz) × d. Here, nx is a refractive index in which the refractive index in the plane becomes the largest (ie, the direction of the slow axis), and nz is the refractive index in the thickness direction.

In the present invention, the phase difference ratio R0/Rth is also important, and the phase difference ratio R0/Rth is preferably 0.01 to 0.5, from the viewpoint of further improving the effect of suppressing rainbow lines and obtaining sufficient strength. 0.02~0.47, more preferably 0.04~0.45.

The dimensional shrinkage ratio of the transparent resin film after heating at 80 ° C for 240 hours is preferably 2.0% or less, more preferably 1.0% or less.

The crystallinity of the transparent resin film measured by X-ray diffraction (XRD) is preferably 25% or more, preferably 30% or more. The upper limit of crystallinity is, for example, 70%. When the degree of crystallinity is in this range, there is an advantage that the film does not shrink when the film is stretched and the optical characteristics such as the phase difference and the alignment angle are not easily changed.

The thickness of the transparent resin film is preferably from 5 to 50 μm, preferably from 7 μm to 40 μm, more preferably from 10 to 30 μm, from the viewpoint of obtaining the above-described in-plane retardation and thickness direction retardation and improving workability.

The glass transition temperature of the polyester resin is preferably from 65 ° C to 80 ° C, more preferably from 70 ° C to 75 ° C. If the glass transition temperature is too low, there is a case where the desired dimensional shrinkage cannot be obtained. If the glass transition temperature is too high, the molding stability at the time of film formation may be deteriorated, and the transparency of the film may be impaired. Further, the glass transition temperature was determined in accordance with JIS K 7121 (1987).

The weight average molecular weight of the polyester resin is preferably from 10,000 to 100,000, preferably from 15,000 to 50,000. If the weight average molecular weight is used for this purpose, a film which is easy to handle and has excellent mechanical strength at the time of molding can be obtained.

The polyester resin can be formed into a film by any appropriate method. The obtained polyester-based resin film can be used as a biaxially stretched film by a method of extending the longitudinal and transverse directions. In this case, as disclosed in Japanese Laid-Open Patent Publication No. 2015-72376, a transparent resin film having an alignment axis in the oblique direction can be suitably obtained by providing a manufacturing method including oblique stretching.

That is, the transparent resin film used in the present invention can be suitably produced by a manufacturing method including oblique stretching, which comprises the following steps: the left and right jig clamping of the variable pitch type which can be changed by the longitudinal jig pitch Extending the left and right ends of the film of the object (step A: holding step); preheating the film (step B: preheating step); changing the jig spacing of the left and right jigs independently, and tilting the film Extension (step C: extension step); heat-treating the film to be crystallized in a state where the jig pitch of the left and right jigs is fixed as needed (step D: crystallization step); Film clamp (step E: release step).

In the transparent resin film, an etching treatment such as sputtering, corona discharge, fire spraying, ultraviolet irradiation, electron beam irradiation, chemical change, oxidation, or a primer coating treatment may be performed on the surface to form a transparent resin film thereon. The adhesion between the optical adjustment layer, the cured resin layer, and the transparent conductive film is improved. Further, before the formation of the optical adjustment layer or the like, the surface of the transparent resin film may be degreased and cleaned by solvent washing or ultrasonic cleaning.

(Cured Resin Layer) The cured resin layer includes a first cured resin layer provided on one of the first main surface sides of the transparent resin film, and a second cured resin layer provided on the second main surface side on the opposite side. Since the transparent resin film is easily damaged in the formation of the transparent conductive film, the patterning of the transparent conductive film, or the mounting of the electronic device, it is preferable to form the first cured resin layer and the second surface on both surfaces of the transparent resin film as described above. Hardened resin layer.

The hardened resin layer is a layer obtained by hardening a hardening type resin. The resin to be used is not particularly limited, and the film obtained by forming the cured resin layer may have sufficient strength and transparency, and examples thereof include a thermosetting resin, an ultraviolet curable resin, and an electron beam curing resin. Two-liquid mixed resin and the like. Among them, it is preferable to form an ultraviolet curable resin which can efficiently form a cured resin layer by a simple processing operation by a hardening treatment by ultraviolet irradiation.

Examples of the ultraviolet curable resin include various resins such as polyester-based, acrylic-based, urethane-based, guanamine-based, polyfluorene-based, and epoxy-based resins, and include ultraviolet curable monomers and oligomers. Polymers, etc. The ultraviolet curable resin to be preferably used is an acrylic resin or an epoxy resin, and more preferably an acrylic resin.

The hardened resin layer may also contain particles. By arranging the particles in the cured resin layer, ridges can be formed on the surface of the cured resin layer, and the transparent conductive film can be appropriately provided with anti-adhesion.

As the particles, any of metal oxides, glass, plastics, and the like having transparency can be used without particular limitation. Examples thereof include inorganic particles such as cerium oxide, aluminum oxide, titanium oxide, zirconium oxide, and calcium oxide, and polymethyl methacrylate, polystyrene, polyurethane, acrylic resin, and acrylic acid-styrene. Crosslinked or uncrosslinked organic particles or polyoxynoid particles formed by various polymers such as copolymers, benzoguanamine, melamine, and polycarbonate. The particles may be used singly or in combination of two or more kinds, but organic particles are preferred. From the viewpoint of the refractive index, the organic particles are preferably an acrylic resin.

The particle size of the particles is appropriately set in consideration of the relationship between the protrusion degree of the cured resin layer and the thickness of the flat region other than the ridge, and is not particularly limited. In addition, from the viewpoint of sufficiently imparting anti-adhesion to the transparent conductive film and sufficiently suppressing an increase in haze, the particle size of the particles is preferably 0.1 to 3 μm, preferably 0.5 to 2.5 μm. In the present specification, the "quantity particle diameter" is a particle diameter indicating the maximum value of the particle distribution, and is specified by using a flow type particle image analyzer (product name "FPTA-3000S", manufactured by Sysmex Corporation). The conditions were determined by measuring (Sheath solution: ethyl acetate, measurement mode: HPF measurement, measurement method: total count). For the measurement sample, a sample obtained by diluting the particles with ethyl acetate to 1.0% by weight and uniformly dispersing the mixture using an ultrasonic cleaner was used.

The content of the particles is preferably 0.05 to 1.0 part by weight, preferably 0.1 to 0.5 part by weight, more preferably 0.1 to 0.2 part by weight, per 100 parts by weight of the solid content of the resin composition. When the content of the particles in the cured resin layer is small, it is difficult to form a sufficient ridge to impart anti-adhesion and slipperiness to the surface of the cured resin layer. On the other hand, when the content of the particles is too large, the haze of the transparent conductive film is increased due to light scattering by the particles, and the visibility is lowered. In addition, when the content of the particles is too large, there are cases where lines are formed during the formation of the cured resin layer (during application of the solution), and the visibility or the electrical properties of the transparent conductive film are not uniform.

The cured resin layer can be obtained by coating a resin composition containing each of the curable resin and optionally added particles, a crosslinking agent, a starter, a sensitizer, or the like on the transparent resin film. When the resin composition contains a solvent, the solvent is dried and hardened by applying heat, an active energy ray or both. As the heat, an well-known mechanism such as an air circulation type oven or an IR heater can be used, but the method is not limited thereto. Examples of the active energy ray include ultraviolet rays, electron beams, gamma rays, and the like, but are not particularly limited.

The hardened resin layer can be formed into a film by a wet coating method (coating method) or the like using the above materials. For example, when indium oxide (ITO) containing tin oxide is formed as a transparent conductive film, the surface of the cured resin layer as the underlayer is smooth, and the crystallization time of the transparent conductive film can be shortened. From this point of view, the cured resin layer is preferably formed by a wet coating method.

The thickness of the cured resin layer is preferably from 0.5 μm to 5 μm, preferably from 0.7 μm to 3 μm, and most preferably from 0.8 μm to 2 μm. When the thickness of the cured resin layer is within the above range, it is possible to prevent damage or prevent film wrinkles in hardening and shrinkage of the cured resin layer, and it is possible to prevent deterioration of visibility of a touch panel or the like.

(Transparent Conductive Film) The transparent conductive film may be provided on the transparent resin film, and is preferably provided on the first hardened resin layer provided on one of the first main surface sides of the transparent resin film. The constituent material of the transparent conductive film is not particularly limited as long as it contains an inorganic substance, and may be suitably selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, cerium, zirconium, magnesium, aluminum, gold, silver, copper, and palladium. a metal oxide of at least one metal of the group consisting of tungsten. Further, in the metal oxide, a metal atom represented by the above group may be further contained as needed. For example, indium oxide (ITO) containing tin oxide, tin oxide containing bismuth (ATO), or the like is preferably used. When indium oxide containing tin oxide is used, the content of tin oxide is preferably 1 to 20% by weight, preferably 3 to 15% by weight, based on the transparent conductive film.

The thickness of the transparent conductive film is not particularly limited, but a continuous film having a surface resistance of 1 × 10 ³ Ω/□ or less and having good conductivity is preferably 10 nm or more. If the film thickness is too large, the transparency is lowered, and the like, and it is preferably in the range of 15 to 35 nm, preferably 20 to 30 nm. When the thickness of the transparent conductive film is less than 10 nm, the electric resistance of the surface of the film becomes high and it is difficult to form a continuous film. Further, when the thickness of the transparent conductive film exceeds 35 nm, the transparency may be lowered.

The method for forming the transparent conductive film is not particularly limited, and a conventionally known method can be employed. Specifically, for example, a dry process such as a vacuum deposition method, a sputtering method, or an ion plating method can be exemplified. Further, an appropriate method can be employed depending on the film thickness required. In the case where the transparent conductive film is formed on the first cured resin layer, the surface of the transparent conductive film substantially maintains the surface shape of the first hardened resin layer as the underlayer thereof by forming a transparent conductive film by a dry process such as sputtering. . Therefore, in the case where the first cured resin layer is embossed, the surface of the transparent conductive film is appropriately imparted with adhesion resistance and smoothness.

The transparent conductive film may be crystallized by heat annealing treatment (for example, at 80 to 150 ° C for 30 to 90 minutes in an atmosphere). By crystallizing the transparent conductive film, in addition to lowering the resistance of the transparent conductive film, transparency and durability are also improved. The method of converting the amorphous transparent conductive film into a crystalline substance is not particularly limited, and an air circulating oven, an IR heater, or the like can be used.

The definition of "crystalline" is a transparent conductive film in which a transparent conductive film is formed on a transparent resin film, and immersed in hydrochloric acid at a concentration of 5 wt% for 15 minutes at 20 ° C, and then washed with water and dried to measure 15 mm. The resistance between the terminals was measured. When the resistance between the terminals did not exceed 10 kΩ, the conversion of the ITO film toward the crystal was completed.

Further, the transparent conductive film may be patterned by etching or the like. The patterning of the transparent conductive film can be carried out using a technique known from the conventional photolithography method. As the etching solution, an acid is preferably used. Examples of the acid include inorganic acids such as hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid, and phosphoric acid; organic acids such as acetic acid; and mixtures thereof; and aqueous solutions thereof. For example, in a transparent conductive film used for a capacitive touch panel or a matrix resistive touch panel, the transparent conductive film is preferably patterned into stripes. Further, when the transparent conductive film is patterned by etching, if the crystallization of the transparent conductive film is performed first, it may be difficult to pattern by etching. Therefore, the annealing treatment of the transparent conductive film is preferably performed after patterning the transparent conductive film.

The transparent conductive film may be amorphous or crystalline when the carrier film described later is laminated. For example, the transparent conductive film in which the transparent conductive film is in an amorphous state can be bonded to the crystalline film after being bonded to the protective film via the adhesive layer.

The aforementioned transparent conductive film may comprise a metal nanowire. The metal nanowire refers to a conductive material whose material is a metal, has a needle shape or a linear shape, and has a diameter of a nanometer. The metal nanowires may be linear or curved. If a transparent conductive layer made of a metal nanowire is used, the metal nanowire becomes a mesh shape, and even a small amount of the metal nanowire can form a good electrical conduction path, and a transparent conductive having a small electrical resistance can be obtained. Film. Further, by forming the metal nanowire into a mesh shape, an opening can be formed in the gap of the mesh, and a transparent conductive film having a high light transmittance can be obtained.

As the metal constituting the metal nanowire, any metal having a high conductivity may be used, and any appropriate metal may be used. Examples of the metal constituting the metal nanowire include silver, gold, copper, nickel, and the like. Further, a material which is plated with such a metal (for example, gold plating treatment) may also be used. Among them, from the viewpoint of conductivity, silver, copper or gold is preferred, and silver is more preferred.

(Optical Adjustment Layer) In the present invention, one or more optical adjustment layers may be further included between the transparent resin film or the first cured resin layer and the transparent conductive film. When the transmittance of the transparent conductive film is increased or the transparent conductive film is patterned, the optical adjustment layer can reduce the difference in transmittance or the difference in reflectance between the pattern portion where the pattern remains and the opening portion where the pattern is not left. A transparent conductive film excellent in visibility is obtained.

The refractive index of the optical adjustment layer is preferably from 1.5 to 1.8, preferably from 1.51 to 1.78, more preferably from 1.52 to 1.75. Thereby, the difference in transmittance or the difference in reflectance can be reduced, and a transparent conductive film excellent in visibility can be obtained.

The optical adjustment layer is formed by an inorganic substance, an organic substance, or a mixture of an inorganic substance and an organic substance. Examples of the material for forming the optical adjustment layer include NaF, Na ₃ AlF ₆ , LiF, MgF ₂ , CaF ₂ , SiO ₂ , LaF ₃ , CeF ₃ , Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , and ZrO _{2 .} , inorganic substances such as ZnO, ZnS, SiO _x (x is 1.5 or more, less than 2), or organic substances such as acrylic resin, epoxy resin, urethane resin, melamine resin, alkyd resin, and decane-based polymer. . In particular, as the organic substance, a thermosetting resin containing a mixture of a melamine resin, an alkyd resin and an organic decane condensate is preferably used. The optical adjustment layer can be formed by a coating method such as a wet method, a gravure coating method, or a bar coating method, a vacuum deposition method, a sputtering method, an ion plating method, or the like using the above materials.

The optical adjustment layer may also have nano fine particles having an average particle diameter of 1 nm to 500 nm. The content of the nanoparticles in the optical adjustment layer is preferably from 0.1% by weight to 90% by weight. The average particle diameter of the nanoparticles used in the optical adjustment layer is preferably in the range of 1 nm to 500 nm, preferably 5 nm to 300 nm, as described above. Further, the content of the nanoparticles in the optical adjustment layer is preferably from 10% by weight to 80% by weight, more preferably from 20% by weight to 70% by weight. The adjustment of the refractive index of the optical adjustment layer itself can be easily performed by containing the nanoparticles in the optical adjustment layer.

Examples of the inorganic oxide forming the nanoparticles include fine particles such as cerium oxide (cerium oxide), hollow nano cerium oxide, titanium oxide, aluminum oxide, zinc oxide, tin oxide, zirconium oxide, and cerium oxide. Among these, fine particles of cerium oxide (cerium oxide), titanium oxide, aluminum oxide, zinc oxide, tin oxide, zirconium oxide, and cerium oxide are preferable. These may be used alone or in combination of two or more.

The thickness of the optical adjustment layer is preferably from 10 nm to 200 nm, preferably from 20 nm to 150 nm, more preferably from 30 nm to 130 nm. If the thickness of the optical adjustment layer is too small, it is difficult to form a continuous film. Further, when the thickness of the optical adjustment layer is too large, the transparency of the transparent conductive film is lowered or cracking tends to occur.

(Metal Layer, Metal Wiring) In the present invention, a metal layer or a metal wiring may be provided on the transparent conductive film. Although the metal wiring may be formed by etching after forming a metal layer on the transparent conductive film, it is preferably formed by using a photosensitive metal paste as follows. In other words, after patterning the transparent conductive film, a metal conductive paste is applied onto the transparent resin film or the transparent conductive film to form a photosensitive metal paste layer, and the mask is laminated or close thereto. The photoreceptor exposes the photosensitive metal paste layer, and then develops and forms a pattern, which is obtained through a drying step. That is, the pattern of the metal wiring can be formed by a well-known photolithography method or the like.

The photosensitive conductive paste preferably contains conductive particles such as metal powder and a photosensitive organic component. The material of the conductive particles of the metal powder is preferably a material containing at least one selected from the group consisting of Ag, Au, Pd, Ni, Cu, Al, and Pt, and more preferably Ag. The volume average particle diameter of the conductive particles of the metal powder is preferably from 0.1 μm to 2.5 μm.

The conductive particles other than the metal powder may be metal-coated resin particles coated with metal on the surface of the resin particles. The material of the resin particles may include the above-mentioned particles, but an acrylic resin is preferred. The metal-coated resin particles can be obtained by reacting a decane coupling agent with the surface of the resin particles and further coating the surface with a metal. By using a decane coupling agent, the dispersion of the resin component can be stabilized to form uniform metal-coated resin particles.

The photosensitive conductive paste may further contain a glass frit. The glass frit preferably has a volume average particle diameter of 0.1 μm to 1.4 μm, a 90% particle diameter of preferably 1 to 2 μm, and a maximum size of 4.5 μm or less. The composition of the glass frit is not particularly limited, but it is preferable to mix Bi ₂ O _{3 in a} range of 30% by weight to 70% by weight based on the whole. The oxide which may be contained other than Bi ₂ O ₃ may include SiO ₂ , B ₂ O ₃ , ZrO ₂ , and Al ₂ O ₃ . Preferably, the alkali-free glass frit is substantially not contained in Na ₂ O, K ₂ O, and Li ₂ O.

The photosensitive organic component preferably contains a photosensitive polymer and/or a photosensitive monomer. As the photosensitive polymer, a polymer containing a component selected from a compound having a carbon-carbon double bond such as methyl (meth)acrylate or ethyl (meth)acrylate or a copolymer thereof is preferably used for the acrylic resin. A photoreactive group or the like is added to a side chain or a molecular end. The photoreactive group is preferably an ethylenically unsaturated group such as a vinyl group, an allyl group, an acryl group or a methacryl group. The content of the photosensitive polymer is preferably from 1 to 30% by weight and from 2 to 30% by weight.

Examples of the photosensitive monomer include (meth)acrylate monomers such as methacryl acrylate and ethyl acrylate, or γ-methacryloxypropyltrimethoxydecane and 1-vinyl-2. - Pyrrolidone or the like may be used alone or in combination of two or more.

In the photosensitive conductive paste, the photosensitive organic component is preferably contained in an amount of 5 to 40% by weight based on 100 parts by weight of the metal powder, and preferably 10 parts by weight to 30 parts by weight. Moreover, it is preferable to use a photopolymerization initiator, a sensitizer, a polymerization inhibitor, and an organic solvent as the photosensitive conductive paste of this invention.

The thickness of the metal layer is not particularly limited. For example, when a pattern wiring is formed by removing one portion of the metal layer by etching or the like, the thickness of the metal layer is appropriately set so that the pattern wiring after formation has a desired resistance value. Therefore, the thickness of the metal layer is preferably from 0.01 to 200 μm, preferably from 0.05 to 100 μm. If the thickness of the metal layer is within the above range, the resistance of the pattern wiring does not become too high, and the power consumption of the device is not excessively large. Further, the production efficiency of the film formation of the metal layer is improved, and the accumulated heat at the time of film formation becomes small, and heat wrinkles are less likely to occur in the film.

When the transparent conductive film is a transparent conductive film for a touch panel used in combination with a display, a portion corresponding to the display portion is formed by a patterned transparent conductive film, and a metal wiring made of a photosensitive conductive paste is used for non- The wiring portion of the display portion (for example, the peripheral portion). The transparent conductive film can also be used for the non-display portion, in which case the metal wiring can be formed on the transparent conductive film.

<Carrier Film> In the present invention, the transparent conductive film may have a carrier film. The carrier film has an adhesive layer on at least one side of the protective film. The carrier film is peelably bonded to the second main surface side of the transparent conductive film via the adhesive layer and the transparent conductive film to form a transparent conductive film. When the carrier film is peeled off from the transparent conductive film, the adhesive layer may be peeled off together with the protective film, or only the protective film may be peeled off.

(Protective Film) As the material for forming the protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, and isotropic properties is preferable. As the protective film, a film formed of a crystalline resin or an amorphous resin can be used.

The crystalline resin may, for example, be a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, or a polyolefin resin such as polyethylene or polypropylene, and is preferably a polyester resin.

The amorphous resin may, for example, be a cycloolefin resin or a polycarbonate resin. From the viewpoint of having excellent light transmittance, scratch resistance, water resistance and good mechanical properties, polycarbonate is preferred. Resin. Examples of the polycarbonate resin include an aliphatic polycarbonate, an aromatic polycarbonate, and an aliphatic-aromatic polycarbonate.

The protective film is the same as the transparent resin film, and may be previously subjected to etching, corona discharge, fire blasting, ultraviolet ray irradiation, electron beam irradiation, chemical change, oxidation, or the like on the surface to adhere to the protective film. The adhesion of the agent layer or the like is improved. Further, before the formation of the adhesive layer, the surface of the protective film may be dedusted and purified by solvent washing or ultrasonic cleaning.

The thickness of the protective film is preferably from 20 to 150 μm, preferably from 30 to 100 μm, more preferably from 40 to 80 μm, from the viewpoint of improving workability and the like.

(Adhesive Layer) The adhesive layer may be any one as long as it has transparency, and can be used without particular limitation. Specifically, for example, a material using a polymer as a base polymer, that is, an acrylic polymer, a polyoxymethylene polymer, a polyester, a polyurethane, a polyamide, a poly A polymer such as a vinyl ether, a vinyl acetate/vinyl chloride copolymer, a modified polyolefin, an epoxy-based, a fluorine-based, a natural rubber, or a synthetic rubber. In particular, an acrylic pressure-sensitive adhesive is preferably used because it is excellent in optical transparency, moisture permeability, cohesiveness and adhesion, and weather resistance and heat resistance.

The method for forming the adhesive layer is not particularly limited, and examples thereof include a method in which a release liner is applied to an adhesive composition, and after drying, transfer to a base film (transfer method), and an adhesive composition is directly applied to the protective film. A method of drying it (direct printing method) or a method of co-extrusion. Further, in the adhesive, an adhesive agent, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a decane coupling agent, or the like may be appropriately used as needed. The thickness of the adhesive layer is preferably from 5 μm to 100 μm, preferably from 10 μm to 50 μm, more preferably from 15 μm to 35 μm.

<Characteristics of Transparent Conductive Film> The transparent conductive film of the present invention preferably has a Δx of 0.15 or less and a Δy of 0.20 or less, more preferably Δx, as a variation in the xy color of the rainbow pattern in the examples. It is 0.13 or less, and Δy is 0.17 or less.

In the case where the above-mentioned characteristics are used, when the transparent resin film is used alone, the variation in the xy color is preferably Δx of 0.15 or less, Δy of 0.20 or less, more preferably Δx of 0.13 or less, and Δy of 0.17. the following.

<Touch Panel> A transparent conductive film obtained by peeling a carrier film or a protective film from a transparent conductive film can be suitably used as a transparent electrode of an electronic device such as a touch panel such as a capacitive or resistive film.

When the touch panel is formed, another substrate such as glass or polymer film may be bonded to one or both main surfaces of the transparent conductive film via a transparent adhesive layer. For example, a laminate in which a transparent substrate is bonded to a surface of the transparent conductive film on the side where the transparent conductive film is not formed via a transparent adhesive layer may be formed. The transparent substrate may be formed of a single base film, or may be a laminate of two or more base films (for example, laminated via a transparent adhesive). Further, a hard coat layer may be provided on the outer surface of the transparent substrate bonded to the transparent conductive film. As the adhesive layer for bonding the transparent conductive film and the substrate, as long as it has transparency, it can be used without particular limitation.

When the transparent conductive film of the present invention is used for forming a touch panel, by using a polyester having a low phase difference as a substrate, it is possible to provide a material having sufficient material strength, a low material cost, good productivity, and sufficient availability. A touch panel having a transparent conductive film that suppresses the effect of rainbow lines. For applications other than touch panels, it can be used to shield electromagnetic waves or noise from electronic devices. [Examples]

Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to the following examples. In addition, the physical properties and the like in the examples and the like were measured as described below.

(Phase Difference) The in-plane retardation of the transparent resin film was measured at a measurement wavelength of 590 nm in an environment of 23 ° C using a polarization/phase difference measurement system (product name "AxoScan"). Further, by the same method, the phase difference when the film was tilted by 40° with the slow axis direction and the phase axis direction as the center of rotation was measured. In addition, the number of times of the measured value of the phase difference is determined so as to be dispersed in accordance with the wavelength difference of the phase difference of the transparent resin film obtained in advance. From the measured values, the in-plane retardation value (R0) of the transparent resin film and the thickness direction retardation value (Rth) were calculated.

(Measurement of Thickness) For the thickness of 1 μm or more, the thickness was measured by a microgauge type thickness meter (manufactured by Mitutoyo Co., Ltd.). Further, the thickness was less than 1 μm or the thickness of the optical adjustment layer was measured by an instantaneous multi-time measuring system (MCPD2000 manufactured by Otsuka Electronics Co., Ltd.). For the thickness of the nanometer, such as the thickness of the ITO film, a sample for cross-section observation was prepared by FB-2000A (manufactured by Hitachi High-Technologies Co., Ltd.), and HF-2000 (manufactured by Hitachi High-Technologies Co., Ltd.) was used for the cross-sectional TEM observation. The film thickness was measured. The evaluation results are shown in Table 1.

(Evaluation of Rainbow Pattern) The evaluation method of the rainbow pattern is based on the xy color and the four-stage evaluation (◎~×). The evaluation of the deviation of the xy color was carried out using a conopolar polarimeter (Conoscope manufactured by Autronic-Melchers Co., Ltd.), and was used for a high-intensity backlight in which a commercially available polarizing plate was disposed. The transparent conductive film is placed on the slow axis of the substrate (ie, the alignment axis) so as to be 45° with respect to the absorption axis of the first polarizing plate, and the absorption axis is opposite to the transparent conductive film. The second polarizing plate is further placed on the absorption axis of the first polarizing plate in an orthogonal manner, and the x value is measured from the omnidirectional (polar angle 0° to 80°, azimuth angle 0° to 360°) by a cone polarizer. The value of y is used to evaluate the deviation of the xy color at this time. The smaller the Δx and Δy, the more the rainbow pattern is suppressed, and Δx is 0.15 or less, and Δy is 0.20 or less, which is a good standard for suppressing rainbow stripes.

Moreover, the four-stage evaluation by visual observation, ×: the hue changes significantly with respect to the angle change, Δ: the angle range in which the hue changes significantly is approximately the range of the polar angle of 40 to 60°, which is narrower than the above 1, ○: the hue changes significantly. The angular range is approximately in the range of the polar angle of 40 to 50°, which is narrower than the above 2, and ◎: almost no change in hue is observed with respect to the change in angle.

[Examples 1 to 7] Various polyethylene terephthalate having an in-plane retardation value (R0), a thickness direction retardation value (Rth), and a thickness shown in Table 1 were prepared by changing the conditions of the biaxial stretching. A diester (PET) is used as a transparent resin film.

The transparent resin film was used as a substrate, and an ultraviolet curable composition containing a zirconia particle having a refractive index of 1.62 (manufactured by JSR Corporation, trade name "OPSTAR Z7412") was applied as an optical adjustment layer on one surface thereof to form a coating layer. . Next, the coating layer was irradiated with ultraviolet rays from the side on which the coating layer was formed, and the optical adjustment layer was formed so as to have a thickness of 100 nm.

Next, the PET film on which the optical adjustment layer was formed was placed in a take-up sputtering apparatus, and an amorphous indium tin oxide layer (composition: SnO ₂ : 10 wt%) having a thickness of 27 nm was formed on the surface of the optical adjustment layer to form a transparent film. Conductive film. A transparent conductive film was produced in this manner.

[Comparative Examples 1 to 11] In Example 1, except for using various in-plane retardation (R0), thickness direction retardation (Rth) and thickness of various polyethylene terephthalate shown in Table 1, A transparent conductive film was produced under the same conditions as in Example 1 except that (PET) was used as the substrate.

The evaluation results of the above transparent conductive film are shown in Table 1.

[Table 1]

As shown in the results of Table 1, the transparent conductive films of Examples 1 to 7 had an in-plane retardation value of 150 nm or less and a thickness direction retardation of 1000 nm or less. Therefore, Δx was 0.15 or less and Δy was 0.20 or less, and visual observation was carried out. The evaluation is also a good result, and the rainbow pattern can be sufficiently suppressed. This means that the rainbow pattern when the display is viewed through the polarized sunglasses can be suppressed. On the other hand, in Comparative Examples 1 to 11 in which the in-plane retardation value exceeded 150 nm or the thickness direction retardation value exceeded 1000 nm, at least one of Δx and Δy was large, and the result of the squint evaluation was also poor, and the rainbow pattern was suppressed. Insufficient effect.

[Example 8] A transparent conductive film was produced in the same manner as in Example 1 except that the PET film was formed with a cured resin layer as described below.

First, a curable resin composition containing spherical particles is contained, and the curable resin composition contains 100 parts by weight of an ultraviolet curable resin composition (trade name "UNIDIC (registered trademark) RS29-120" manufactured by DIC Corporation), and 0.2 parts by weight of acrylic spherical particles having a mode diameter of 1.9 μm (manufactured by Soken Chemical Co., Ltd., trade name "MX-180TA").

The prepared curable resin composition containing spherical particles was applied to one surface of a PET substrate at a thickness of 50 μm to form a coating layer. Next, the coating layer was irradiated with ultraviolet rays from the side on which the coating layer was formed, and the second cured resin layer was formed so as to have a thickness of 1.0 μm. The first cured resin layer was formed on the other surface of the PET substrate so that the thickness became 1.0 μm by the same method except that the spherical particles were not added. Further, the optical adjustment layer and the transparent conductive film are formed on the surface of the first cured resin layer.

The obtained transparent conductive film was evaluated for rainbow pattern, and as a result, Δx and Δy which were substantially the same as those of Example 1 were obtained, and the visual evaluation was also good, and the rainbow pattern was sufficiently suppressed.

1‧‧‧Protective film
2‧‧‧Adhesive layer
3‧‧‧2nd hardened resin layer (anti-adhesive layer)
4‧‧‧Transparent resin film
5‧‧‧1st hardened resin layer (hard coating)
6‧‧‧Transparent conductive film
7‧‧‧Optical adjustment layer
10‧‧‧ Carrier film
20‧‧‧Transparent conductive film

Fig. 1 is a schematic cross-sectional view showing a transparent conductive film according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing a transparent conductive film according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing a transparent conductive film according to an embodiment of the present invention. Fig. 4 is a schematic cross-sectional view showing a transparent conductive film according to an embodiment of the present invention. Fig. 5 is a schematic cross-sectional view showing a transparent conductive film according to an embodiment of the present invention. Fig. 6 is a schematic cross-sectional view showing a transparent conductive film according to an embodiment of the present invention.

4‧‧‧Transparent resin film

6‧‧‧Transparent conductive film

7‧‧‧Optical adjustment layer

20‧‧‧Transparent conductive film

Claims (7)

A transparent conductive film having a transparent resin film and a transparent conductive film; wherein the transparent resin film is a biaxially stretched polyester resin film having an in-plane retardation value of 150 nm or less and a thickness direction retardation of 1000 nm or less . The transparent conductive film of claim 1, wherein the transparent resin film and the transparent conductive film have at least one optical adjustment layer. The transparent conductive film of claim 1, wherein the transparent resin film has a thickness of 5 to 50 μm. The transparent conductive film of claim 1, wherein the transparent resin film is an elongated body or a rectangular monolith, and the alignment axis has an angle of 10 to 45 with respect to the long side or the short side. The transparent conductive film of claim 1, wherein at least one surface of the transparent resin film has a hardened resin layer. The transparent conductive film according to any one of claims 1 to 5, wherein an adhesive layer and a protective film are sequentially provided on a side of the transparent resin film on which the transparent conductive film is not provided. A touch panel obtained by using the transparent conductive film according to any one of claims 1 to 6.