JP2017062609A - Transparent conductive film and touch panel including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film using a polyester with low phase difference as a substrate, enabling a sufficient material strength, a lower material cost, and excellent productivity, as well as a sufficient restrictive effect on iridescent irregularity, and also to provide a touch panel including the same.SOLUTION: A transparent conductive film 20 includes a transparent resin film 4 and a transparent conductive membrane 6. The transparent resin film 4 is a biaxially-drawn polyester resin film, and has an in-plane phase difference value of 150 nm or less and a thickness direction phase difference value of 1000 nm or less.SELECTED DRAWING: Figure 1

Description

  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 same.

  Recently, with the spread of tablets, smartphones, and PCs with touch panels, opportunities to handle electronic devices outdoors have increased. When viewing the display outdoors, it is often viewed with polarized sunglasses. If a transparent conductive film using a polyethylene terephthalate (PET) film is used, the in-plane position of the PET film itself There is a problem that rainbow unevenness occurs due to the phase difference (generally 1000 to 2000 nm), and the visibility of the display is greatly reduced.

  For this reason, development of a transparent conductive film using a substrate (such as a cyclic olefin resin) having a small retardation value has been advanced. However, the cyclic olefin resin has a demerit that the material strength is weak and the material itself is expensive, and the use of an inexpensive and high strength material is being studied.

  For this reason, Patent Document 1 proposes a transparent conductive film based on a transparent resin film made of stretched polyester or the like having an in-plane retardation value of 4000 nm or more. According to this transparent conductive film, color unevenness is less likely to occur even when viewed through polarized sunglasses.

Japanese Patent Laid-Open No. 2004-214069

  However, such a polyester film having a large in-plane retardation value has a low material strength due to uniaxial stretching, and a thick film for increasing the retardation, resulting in an increase in material cost and poor productivity. There are disadvantages and it is difficult to handle as a general-purpose material.

  Therefore, the object of the present invention is to use a low retardation polyester as a base material, which has sufficient material strength, low material cost, good productivity, and sufficient rainbow unevenness suppression effect. An object of the present invention is to provide a transparent conductive film and a touch panel including the transparent conductive film.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors use a biaxially stretched polyester resin film in which the in-plane retardation value and the thickness direction retardation value are in a predetermined range as a base material. Thus, the inventors have found that the above object can be achieved, and have reached the present invention.

  That is, the transparent conductive film of the present invention is a transparent conductive film having a transparent resin film and a transparent conductive film, and the transparent resin film is a biaxially stretched polyester-based resin film and has an in-plane position. The phase difference value is 150 nm or less, and the thickness direction retardation value is 1000 nm or less. In addition, the various physical property values in the present invention are values measured by a method employed in Examples and the like.

  In general, a biaxially stretched polyester-based resin film has sufficient material strength and is inexpensive, but has an in-plane retardation of about 1000 to 2000 nm, and this is used as a substrate for a transparent conductive film. If used, the effect of depolarizing polarized light by wavelength dispersion becomes insufficient, and rainbow unevenness occurs. In contrast, when a polyester resin film having an in-plane retardation value of 150 nm or less and a thickness direction retardation value of 1000 nm or less is used as in the present invention, a sufficient rainbow is obtained as shown in the results of the examples. The effect of suppressing unevenness is obtained.

  The details of the reason are not clear, but are considered as follows. That is, when a polyester-based resin film having an in-plane retardation value of 150 nm or less is used, an action of circularly polarizing linearly polarized light (including elliptical polarization) occurs. This is because the thickness direction retardation value is 1000 nm or less. Coupled with the fact that it is possible to suppress a change in color tone with respect to the spread in the viewing direction, it is considered that a sufficient effect of suppressing rainbow unevenness can be obtained.

  As a result, according to the transparent conductive film of the present invention, by using a low retardation polyester as a base material, it has sufficient material strength, low material cost, good productivity, and sufficient rainbow unevenness. The transparent conductive film from which the inhibitory effect is acquired can be provided.

  In the above, it is preferable to have at least one optical adjustment layer 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 part and the pattern opening when the transparent conductive film is patterned can be reduced, and the transparent conductive film pattern is difficult to see, such as a touch panel. Visibility is improved in the display device.

  Moreover, it is preferable that the thickness of the said transparent resin film is 5-50 micrometers. When the thickness is in such a range, a biaxially stretched polyester resin film having an in-plane retardation value of 150 nm or less and a thickness direction retardation value of 1000 nm or less is easily produced at low cost.

  In addition, the transparent resin film is a long or rectangular sheet, and the orientation axis is preferably 10 to 45 ° with respect to the long side or the short side. The transparent conductive film is often used by being laminated on a rectangular optical display device such as a liquid crystal cell, and the light from the optical display device is often polarized parallel or perpendicular to its long side. For this reason, in this invention, it becomes easy to arrange | position a slow axis at an angle of 10-45 degrees with respect to polarization | polarized-light because an orientation axis has an angle of 10-45 degrees with respect to a long side or a short side, and is transparent. The action of circularly polarizing polarized light is increased by the resin film, and a sufficient rainbow unevenness suppressing effect is easily obtained.

  It is preferable to have a cured resin layer on at least one surface of the transparent resin film. The cured resin layer functions as a hard coat layer for preventing scratches during transportation, and can also function as an anti-blocking layer by generating irregularities on the surface.

  It is preferable to have an adhesive layer and a protective film in this order on the side of the transparent resin film where the transparent conductive film is not provided. With the protective film, the handleability is enhanced, and the transparent conductive film of the present invention can be made an adhesive type by configuring the protective film as a separator.

  On the other hand, the touch panel of the present invention is obtained 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 rainbow unevenness suppression effect.

It is typical sectional drawing of the transparent conductive film which concerns on one Embodiment of this invention. It is typical sectional drawing of the transparent conductive film which concerns on one Embodiment of this invention. It is typical sectional drawing of the transparent conductive film which concerns on one Embodiment of this invention. It is typical sectional drawing of the transparent conductive film which concerns on one Embodiment of this invention. It is typical sectional drawing of the transparent conductive film which concerns on one Embodiment of this invention. It is typical sectional drawing of the transparent conductive film which concerns on one Embodiment of this invention.

<Laminated structure of transparent conductive film>
As shown in FIGS. 1 to 3, the transparent conductive film 20 of the present invention includes a transparent resin film 4 and a transparent conductive film 6, and between the transparent resin film 4 and the transparent conductive film 6. It is preferable to have at least one optical adjustment layer 7. Moreover, 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-blocking layer 3 or the hard coat layer 5. Further, as shown in FIGS. 4 to 6, the transparent conductive film 20 has the adhesive layer 2 and the protective film 1 in this order on the side of the transparent resin film 4 where the transparent conductive film 6 is not provided. In this case, the carrier film 10 is composed of the pressure-sensitive adhesive layer 2 and the protective film 1.

(Transparent resin film)
As the transparent resin film, a biaxially stretched polyester resin film is used. “Biaxially stretched” means that the film is stretched in at least two directions, and the bi-directional stretching may be simultaneous or sequential.

  Examples of the polyester resin include polyester resins selected from polyester, modified polyester, and blends thereof. As the polyester, for example, a polyester obtained by condensation polymerization of a carboxylic acid component and a polyol component can be used.

  Examples of the carboxylic acid component include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, benzylmalonic acid, 1,4-naphthalic acid, diphenic 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, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, zebacic acid, fumaric acid, Maleic acid, itaconic acid, thiodipropionic acid, diglycolic acid are mentioned. Examples of the alicyclic dicarboxylic acid include 1,3-cyclopentane dicarboxylic acid, 1,2-cyclohexane dicarboxylic acid, 1,3-cyclopentane dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, and 2,5-norbornane dicarboxylic acid. Examples include acids and adamantane dicarboxylic acids. The carboxylic acid component may be a derivative such as ester, chloride, or acid anhydride. For example, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, dimethyl terephthalate And diphenyl terephthalate. A carboxylic acid component may be used independently and may use 2 or more types together.

  A typical example of the polyol component is a dihydric alcohol. Examples of the dihydric alcohol include aliphatic diols, alicyclic diols, and aromatic diols. Examples of the aliphatic diol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 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- Examples include butadiol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol. It is done. Examples of the alicyclic diol include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, 2,2,4 , 4-tetramethyl-1,3-cyclobutanediol. Examples of the aromatic diol include 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4 '-(2-norbornylidene) diphenol, 4,4'-dihydroxybiphenol, o-, m- and p-dihydroxybenzene, 4,4'-isopropylidenephenol, 4,4'-isopropylidenebis (2,6-cyclophenol) 2,5-naphthalenediol and p-xylenediol. A polyol component may be used independently and may use 2 or more types together.

  Preferred carboxylic acid components include terephthalic acid, isophthalic acid, and 2,5-naphthalenedicarboxylic acid. Preferred polyol components include ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol.

  The structure of the polyester is determined by the combination of monomers as described above. Accordingly, preferred polyester resins include, for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexylene terephthalate, and copolymers, blends and modified products thereof. It is done.

  By using such a polyester-based resin and applying a production method including oblique stretching, a transparent resin film having a preferable in-plane retardation and orientation axis direction, and having better axial accuracy. 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 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. The polyester-based resin may be a modified PET containing a repeating unit derived from isophthalic acid. In this case, the proportion of isophthalic 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. Needless to say, these embodiments may be combined.

  The transparent resin film is produced as a biaxially stretched long film (long body). In the present specification, the “long shape” refers to an elongated shape having a ratio of length to width of 10 or more. The ratio of the length to the width of the transparent resin film is preferably 30 or more, more preferably 100 or more. In one embodiment, the transparent resin film is a long body wound in a roll shape, and in another embodiment, the transparent resin film is a rectangular sheet.

  The orientation axis of the transparent resin film preferably has an angle of 10 to 45 ° with respect to the long side or the short side, more preferably 20 to 45 °, and most preferably 30 to 45 °. In the transparent conductive film of the present invention, the orientation axis of the transparent resin film is preferably disposed at an angle of 10 to 80 ° with respect to the vibration direction of the linearly polarized light emitted from the display device. More preferably, it is arranged at an angle of 70 °, more preferably at an angle of 30-60 °.

  For this reason, the direction of the slow axis of the long film is in the range of 30 ° to 60 °, preferably in the range of 38 ° to 52 °, more preferably 43 over the entire width direction of the film. More preferably, the slow axis direction forms an angle of about 45 ° with respect to the longitudinal direction. The transparent resin film can obtain a transparent resin film having a slow axis in an oblique direction with excellent axial accuracy by applying a production method including oblique stretching.

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

  Here, the in-plane retardation R0 is an in-plane retardation of the film measured with light having a wavelength of 590 nm at 23 ° C. R0 is determined by the formula: R0 = (nx−ny) × d, where d (nm) is the thickness of the film. Here, nx is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction), and ny is the refractive index in the direction perpendicular to the slow axis in the plane.

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

  Here, the thickness direction retardation Rth is the thickness direction retardation of the film measured with light having a wavelength of 590 nm at 23 ° C. Rth is determined by the formula: Rth = (nx−nz) × d, where d (nm) is the thickness of the film. Here, nx is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction), and nz is the refractive index in the thickness direction.

  In the present invention, the phase difference ratio R0 / Rth is also important. From the viewpoint of enhancing the effect of suppressing rainbow unevenness and obtaining sufficient strength, the phase difference ratio R0 / Rth is 0.01 to 0.5. Is preferable, 0.02-0.47 is more preferable, and 0.04-0.45 is still more preferable.

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

  The transparent resin film preferably has a crystallinity measured by X-ray diffraction (XRD) of 25% or more, more preferably 30% or more. The upper limit of the crystallinity is, for example, 70%. When the crystallinity is in such a range, there is an advantage that the film does not shrink when the stretched film is heated, and optical properties such as retardation and orientation angle are hardly changed.

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

  The glass transition temperature of the polyester resin is preferably 65 ° C to 80 ° C, more preferably 70 ° C to 75 ° C. If the glass transition temperature is too low, the desired dimensional shrinkage rate may not be obtained. If the glass transition temperature is excessively high, the molding stability at the time of film molding may deteriorate, and the transparency of the film may be impaired. The glass transition temperature is determined according to JIS K 7121 (1987).

  The weight average molecular weight of the polyester resin is preferably 10,000 to 100,000, more preferably 15,000 to 50,000. If it is such a weight average molecular weight, the handling at the time of shaping | molding is easy, and the film which has the outstanding mechanical strength can be obtained.

  The polyester resin can be formed into a film by any appropriate method. The obtained polyester resin film can be made into a biaxially stretched film by a method of stretching biaxially and horizontally. At that time, as disclosed in JP-A-2015-72376, a transparent resin film having an orientation axis in an oblique direction can be suitably obtained by subjecting it to a production method including oblique stretching.

  That is, the left and right end portions of the film to be stretched are each gripped by variable pitch type left and right clips whose longitudinal clip pitches change (step A: gripping step); the film is preheated (step B) : Preheating step); changing the clip pitch of the left and right clips independently and stretching the film diagonally (step C: stretching step); if necessary, the clip pitch of the left and right clips is constant In this state, the film is heat-treated to be crystallized (step D: crystallization step); and a clip that holds the film is released (step E: release step); The transparent resin film used by this invention can be suitably manufactured with the manufacturing method containing.

  The transparent resin film is subjected to an etching process such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, and undercoating treatment on the surface, and an optical adjustment layer formed on the transparent resin film, cured. You may make it improve adhesiveness with a resin layer, a transparent conductive film, etc. Moreover, before forming an optical adjustment layer etc., you may remove and clean the surface of a transparent resin film by solvent washing | cleaning, ultrasonic washing | cleaning, etc. as needed.

(Cured resin layer)
The cured resin layer includes a first cured resin layer provided on one first main surface side of the transparent resin film and a second cured resin layer provided on the opposite second main surface side. Since the transparent resin film is easily scratched in each process such as formation of a transparent conductive film, patterning of the transparent conductive film, or mounting on an electronic device, the first cured resin is formed on both sides of the transparent resin film as described above. It is preferable to form a layer and a second cured resin layer.

  The cured resin layer is a layer obtained by curing a curable resin. As the resin to be used, those having sufficient strength as a film after forming the cured resin layer and having transparency can be used without particular limitation, but thermosetting resin, ultraviolet curable resin, electron beam curable resin, two-component Examples thereof include mixed resins. Among these, an ultraviolet curable resin that can efficiently form a cured resin layer by a simple processing operation by a curing treatment by ultraviolet irradiation is preferable.

  Examples of the ultraviolet curable resin include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based resins, and include ultraviolet curable monomers, oligomers, polymers, and the like. The ultraviolet curable resin preferably used is an acrylic resin or an epoxy resin, more preferably an acrylic resin.

  The cured resin layer may contain particles. By blending the particles in the cured resin layer, ridges can be formed on the surface of the cured resin layer, and blocking resistance can be suitably imparted to the transparent conductive film.

  As said particle | grains, what has transparency, such as various metal oxides, glass, a plastics, can be especially used without a restriction | limiting. For example, inorganic particles such as silica, alumina, titania, zirconia, calcium oxide, polymethyl methacrylate, polystyrene, polyurethane, acrylic resin, acrylic-styrene copolymer, benzoguanamine, melamine, polycarbonate, and other cross-linked or uncrosslinked polymers. Examples include crosslinked organic particles and silicone particles. The particles can be used by appropriately selecting one type or two or more types, but organic particles are preferable. The organic particles are preferably acrylic resins from the viewpoint of refractive index.

  The mode particle diameter of the particles can be appropriately set in consideration of the degree of protrusion of the cured resin layer and the thickness of a flat region other than the protrusion, and is not particularly limited. In addition, from the viewpoint of sufficiently imparting blocking resistance to the transparent conductive film and sufficiently suppressing increase in haze, the mode particle diameter of the particles is preferably 0.1 to 3 μm, and preferably 0.5 to 2. 5 μm is more preferable. In the present specification, “mode particle size” refers to a particle size showing the maximum value of particle distribution, using a flow type particle image analyzer (product name “FPTA-3000S” manufactured by Sysmex). , By measuring under predetermined conditions (Sheath solution: ethyl acetate, measurement mode: HPF measurement, measurement method: total count). The measurement sample is prepared by diluting the particles to 1.0% by weight with ethyl acetate and uniformly dispersing the particles using an ultrasonic cleaner.

  The content of the particles is preferably 0.05 to 1.0 part by weight, more preferably 0.1 to 0.5 part by weight, based on 100 parts by weight of the solid content of the resin composition. More preferably, it is 1 to 0.2 parts by weight. When the content of the particles in the cured resin layer is small, there is a tendency that bulges sufficient to impart blocking resistance and slipperiness to the surface of the cured resin layer are hardly formed. On the other hand, if the content of the particles is too large, the haze of the transparent conductive film increases due to light scattering by the particles, and the visibility tends to decrease. On the other hand, when the content of the particles is too large, streaks are generated during the formation of the cured resin layer (at the time of application of the solution), and the visibility may be impaired, or the electrical characteristics of the transparent conductive film may be uneven. There is a case.

  The cured resin layer is formed by applying a resin composition containing particles, a crosslinking agent, an initiator, a sensitizer and the like to be added to each curable resin as necessary on a transparent resin film, and the resin composition contains a solvent. Is obtained by drying the solvent and curing by application of either heat, active energy rays or both. For the heat, known means such as an air circulation oven or an IR heater can be used, but it is not limited to these methods. Examples of active energy rays include, but are not limited to, ultraviolet rays, electron beams, and gamma rays.

  The cured resin layer can be formed by the wet coating method (coating method) using the above materials. For example, in the case of forming indium oxide (ITO) containing tin oxide as the transparent conductive film, the crystallization time of the transparent conductive film can be shortened if the surface of the cured resin layer that is the base layer is smooth. 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 0.5 μm to 5 μm, more preferably 0.7 μm to 3 μm, and most preferably 0.8 μm to 2 μm. When the thickness of the cured resin layer is within the above range, it is possible to prevent scratches and film wrinkles in the cured shrinkage of the cured resin layer, and it is possible to prevent the visibility of a touch panel and the like from being deteriorated.

(Transparent conductive film)
The transparent conductive film can be provided on the transparent resin film, but is preferably provided on the first cured resin layer provided on the first main surface side 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. From the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, tungsten A metal oxide of at least one selected metal is preferably used. The metal oxide may further contain a metal atom shown in the above group, if necessary. For example, indium oxide (ITO) containing tin oxide and tin oxide (ATO) containing antimony are preferably used. When using indium oxide containing tin oxide, the content of tin oxide is preferably 1 to 20% by weight, more preferably 3 to 15% by weight in the transparent conductive film.

The thickness of the transparent conductive film is not particularly limited, but the thickness is preferably 10 nm or more in order to obtain a continuous film having good conductivity with a 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 of the transparent conductive film is less than 10 nm, the electrical resistance of the film surface increases and it becomes difficult to form a continuous film. Further, when the thickness of the transparent conductive film exceeds 35 nm, the transparency may be lowered.

  The formation method of a transparent conductive film is not specifically limited, A conventionally well-known method is employable. Specific examples include dry processes such as vacuum deposition, sputtering, and ion plating. In addition, an appropriate method can be adopted depending on the required film thickness. In addition, when forming a transparent conductive film on the 1st hardening resin layer, if the transparent conductive film is formed by dry processes, such as sputtering method, the surface of a transparent conductive film is the 1st hardening which is the foundation layer The surface shape of the resin layer is substantially maintained. Therefore, when a protrusion exists in the 1st cured resin layer, blocking resistance and slipperiness can be suitably given also to the transparent conductive film surface.

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

  Regarding the definition of “crystalline”, a transparent conductive film in which a transparent conductive film is formed on a transparent resin film is immersed in hydrochloric acid having a concentration of 5% by weight at 20 ° C. for 15 minutes, then washed with water and dried for 15 mm. When the inter-terminal resistance is measured with a tester and the inter-terminal resistance does not exceed 10 kΩ, it is assumed that the conversion of the ITO film to crystalline is completed.

  The transparent conductive film may be patterned by etching or the like. The patterning of the transparent conductive film can be performed using a conventionally known photolithography technique. An acid is preferably 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. 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 in a stripe shape. Note that, when the transparent conductive film is patterned by etching, if the transparent conductive film is first crystallized, patterning by etching may be difficult. Therefore, it is preferable to perform the annealing treatment of the transparent conductive film after patterning the transparent conductive film.

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

  The transparent conductive film may include metal nanowires. A metal nanowire is a conductive material having a metal material, a needle shape or a thread shape, and a diameter of nanometer. The metal nanowire may be linear or curved. If a transparent conductive layer composed of metal nanowires is used, the metal nanowires can be formed into a mesh shape, so that even with a small amount of metal nanowires, a good electrical conduction path can be formed, and transparent with low electrical resistance. A conductive film can be obtained. Furthermore, when the metal nanowire has a mesh shape, an opening is formed in the mesh space, and a transparent conductive film having high light transmittance can be obtained.

  Any appropriate metal can be used as the metal constituting the metal nanowire as long as it is a highly conductive metal. As a metal which comprises the said metal nanowire, silver, gold | metal | money, copper, nickel etc. are mentioned, for example. Moreover, you may use the material which performed the plating process (for example, gold plating process) to these metals. Among these, silver, copper, or gold is preferable from the viewpoint of conductivity, and silver is more preferable.

(Optical adjustment layer)
In the present invention, one or more optical adjustment layers can be further included between the transparent resin film or the first cured resin layer and the transparent conductive film. The optical adjustment layer increases the transmittance of the transparent conductive film, or when the transparent conductive film is patterned, the transmittance difference or reflectance difference between the pattern part where the pattern remains and the opening part where the pattern does not remain. Is used to obtain a transparent conductive film excellent in visibility.

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

The optical adjustment layer is formed of an inorganic material, an organic material, or a mixture of an inorganic material and an organic material. As a material for forming the optical adjustment layer, 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 , ZrO ₂ , Examples thereof include inorganic substances such as ZnO, ZnS, and SiO _x (x is 1.5 or more and less than 2), and organic substances such as acrylic resins, epoxy resins, urethane resins, melamine resins, alkyd resins, and siloxane polymers. In particular, it is preferable to use a thermosetting resin made of a mixture of a melamine resin, an alkyd resin, and an organic silane condensate as the organic substance. The optical adjustment layer can be formed using the above materials 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.

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

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

  The thickness of the optical adjustment layer is preferably 10 nm to 200 nm, more preferably 20 nm to 150 nm, and further preferably 30 nm to 130 nm. If the thickness of the optical adjustment layer is too small, it is difficult to form a continuous film. Moreover, when the thickness of the optical adjustment layer is excessively large, the transparency of the transparent conductive film tends to be reduced or cracks tend to occur.

(Metal layer, metal wiring)
In the present invention, it is also possible to provide a metal layer or a metal wiring on the transparent conductive film. The metal wiring can be formed by etching after forming the metal layer on the transparent conductive film, but is preferably formed using a photosensitive metal paste as follows. That is, after the transparent conductive film is patterned, the metal wiring is formed by applying a photosensitive conductive paste described later on the transparent resin film or the transparent conductive film, forming a photosensitive metal paste layer, and forming a photomask. The photosensitive metal paste layer is exposed through a photomask after being laminated or brought close to each other, then developed and patterned to obtain a drying process. That is, the metal wiring pattern can be formed by a known photolithography method or the like.

  The photosensitive conductive paste preferably includes conductive particles such as metal powder and a photosensitive organic component. The material of the conductive particles of the metal powder preferably contains 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 0.1 μm to 2.5 μm.

  The conductive particles other than the metal powder may be metal-coated resin particles in which the resin particle surfaces are coated with metal. As the material of the resin particles, the above-mentioned particles are included, but an acrylic resin is preferable. The metal-coated resin particles are obtained by reacting the surface of the resin particles with a silane coupling agent and coating the surface with metal. By using the silane coupling agent, the dispersion of the resin component is stabilized, and uniform metal-coated resin particles can be formed.

The photosensitive conductive paste may further contain glass frit. The glass frit preferably has a volume average particle size of 0.1 μm to 1.4 μm, a 90% particle size of 1 to 2 μm, and a top size of 4.5 μm or less. As the composition of the glass frit is not particularly limited, Bi ₂ O ₃ is are preferably blended in a range of 30% to 70% by weight relative to the total. Examples of the oxide that may be contained in addition to Bi ₂ O ₃ may include SiO ₂ , B ₂ O ₃ , ZrO ₂ , and Al ₂ O ₃ . Na ₂ O, K ₂ O, and Li ₂ O are preferably alkali-free glass frit that is substantially free of them.

  The photosensitive organic component preferably contains a photosensitive polymer and / or a photosensitive monomer. As the photosensitive polymer, a polymer of a component selected from a compound having a carbon-carbon double bond such as methyl (meth) acrylate, ethyl (meth) acrylate, or a side chain or molecule of an acrylic resin comprising these copolymers. Those having a photoreactive group added to the terminal are preferably used. Preferred photoreactive groups include ethylenically unsaturated groups such as vinyl, allyl, acrylic and methacrylic groups. The content of the photosensitive polymer is preferably 1 to 30% by weight and 2 to 30% by weight.

  Examples of the photosensitive monomer include (meth) acrylate monomers such as methacryl acrylate and ethyl acrylate, γ-methacryloxypropyltrimethoxysilane, 1-vinyl-2-pyrrolidone and the like, and one or more are used. can do.

  In the photosensitive conductive paste, the photosensitive organic component is preferably contained in an amount of 5 to 40% by weight with respect to 100 parts by weight of the metal powder in terms of light sensitivity, and more preferably 10 to 30 parts by weight. The photosensitive conductive paste of the present invention preferably uses a photopolymerization initiator, a sensitizer, a polymerization inhibitor, and an organic solvent as necessary.

  The thickness of the metal layer is not particularly limited. For example, when the pattern wiring is formed by removing a part of the surface of the metal layer by etching or the like, the thickness of the metal layer is appropriately set so that the formed pattern wiring has a desired resistance value. Therefore, the thickness of the metal layer is preferably 0.01 to 200 μm, and more preferably 0.05 to 100 μm. When 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 does not increase. In addition, the production efficiency of the metal layer is increased, the integrated heat amount during the film formation is reduced, and the film is less likely to be thermally wrinkled.

  When the transparent conductive film is a transparent conductive film for a touch panel used in combination with a display, the portion corresponding to the display portion is formed by a patterned transparent conductive film, and a metal wiring made from a photosensitive conductive paste Is used for the wiring part of the non-display part (for example, the peripheral part). The transparent conductive film may be used even in a non-display portion, and in that case, metal wiring may 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 surface side of the protective film. A carrier film bonds a transparent conductive film which can be peeled off through an adhesive layer, and the 2nd main surface side of a transparent conductive film, and forms a transparent conductive film. When peeling the carrier film from the transparent conductive film, the pressure-sensitive adhesive layer may be peeled off together with the protective film, or only the protective film may be peeled off.

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

  Examples of the crystalline resin include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, and polyolefin resins such as polyethylene and polypropylene. Polyester resins are preferred.

  Examples of the amorphous resin include cycloolefin resins and polycarbonate resins, and polycarbonate resins are preferable from the viewpoint of excellent light transmittance, scratch resistance, water resistance, and good mechanical properties. Examples of the polycarbonate-based resin include aliphatic polycarbonate, aromatic polycarbonate, and aliphatic-aromatic polycarbonate.

  Like the transparent resin film, the protective film is subjected to an etching process such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, and undercoating on the surface, and a pressure-sensitive adhesive layer on the protective film, etc. You may make it improve adhesiveness. In addition, before forming the pressure-sensitive adhesive layer, the surface of the protective film may be removed and cleaned by solvent cleaning or ultrasonic cleaning as necessary.

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

(Adhesive layer)
The pressure-sensitive adhesive layer 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.

  The method for forming the pressure-sensitive adhesive layer is not particularly limited. The pressure-sensitive adhesive composition is applied to a release liner, dried and then transferred to a base film (transfer method), and the pressure-sensitive adhesive composition is directly applied to a protective film. And a drying method (direct copying method) and a co-extrusion method. In addition, a tackifier, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a silane coupling agent, and the like can be appropriately used as the pressure-sensitive adhesive. The preferable thickness of the pressure-sensitive adhesive layer is 5 μm to 100 μm, more preferably 10 μm to 50 μm, and more preferably 15 μm to 35 μm.

<Characteristics of transparent conductive film>
In the transparent conductive film of the present invention, Δx is 0.15 or less, Δy is preferably 0.20 or less, and Δx is 0.13 or less, as variations in xy color of evaluation of rainbow unevenness in Examples. , Δy is more preferably 0.17 or less.

  Further, in order to achieve this, when a transparent resin film is used alone, Δx is preferably 0.15 or less and Δy is 0.20 or less, and Δx is 0 or less, as variations in xy color specification. .13 or less and Δy is more preferably 0.17 or less.

<Touch panel>
A transparent conductive film obtained by peeling a carrier film or a protective film from a transparent conductive film can be suitably applied as a transparent electrode of an electronic device such as a touch panel such as a capacitance method or a resistance film method.

  In forming the touch panel, another substrate such as glass or a polymer film can be bonded to one or both principal surfaces of the transparent conductive film described above via a transparent adhesive layer. For example, you may form the laminated body by which the transparent base | substrate was bonded together through the transparent adhesive layer on the surface by which the transparent conductive film of the transparent conductive film is not formed. The transparent substrate may be composed of a single substrate film or may be a laminate of two or more substrate films (for example, laminated via a transparent adhesive layer). A hard coat layer can also be provided on the outer surface of the transparent substrate to be bonded to the transparent conductive film. As described above, the pressure-sensitive adhesive layer used for bonding the transparent conductive film and the substrate can be used without particular limitation as long as it has transparency.

  When the transparent conductive film of the present invention is used for the formation of a touch panel, by using a low retardation polyester as a base material, it has sufficient material strength, low material cost, good productivity, and sufficient It is possible to provide a touch panel having a transparent conductive film capable of obtaining a rainbow unevenness suppressing effect. If it is other than a touch panel use, it can be used for the shield use which shields the electromagnetic waves and noise emitted from an electronic device.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to a following example. In addition, the physical property etc. in an Example etc. were measured as follows.

(Phase difference)
The in-plane retardation of the transparent resin film was measured at a measurement wavelength of 590 nm in a 23 ° C. environment using a polarization / phase difference measurement system (product name “AxoScan” manufactured by Axometrics). Similarly, the phase difference was measured when the film was tilted by 40 ° with the slow axis direction and the fast axis direction as the center of rotation. In addition, the order of the measured value of the phase difference was determined so as to coincide with the wavelength dispersion of the phase difference of the transparent resin film obtained in advance. From these measured values, an in-plane retardation value (R0) and a thickness direction retardation value (Rth) of the transparent resin film were calculated.

(Measurement of thickness)
Thickness was measured with a micro gauge thickness gauge (manufactured by Mitutoyo Corporation) for those having a thickness of 1 μm or more. The thickness of less than 1 μm and the thickness of the optical adjustment layer were measured with an instantaneous multi-photometry system (MCPD2000 manufactured by Otsuka Electronics Co., Ltd.). For nano-sized thickness like the thickness of ITO film etc., FB-2000A (manufactured by Hitachi High-Technologies Co., Ltd.) is used to prepare a sample for cross-sectional observation, and cross-sectional TEM observation is HF-2000 (manufactured by Hitachi High-Technologies Corporation). Was used to measure the film thickness. The evaluation results are shown in Table 1.

(Evaluation of rainbow unevenness)
As a method for evaluating the rainbow unevenness, a variation evaluation with an xy color specification and a four-stage evaluation (◎ to ×) by silent vision were performed.
The xy color variation was evaluated using a conoscope (manufactured by Autronic-Melchers, Conoscope), and a commercially available polarizing plate was placed on a high-luminance backlight. A transparent conductive film is placed so that the direction of the slow axis (that is, the orientation axis) of the substrate is 45 ° with respect to the absorption axis of the first polarizing plate, and further, A second polarizing plate is further placed on the first polarizing plate so that the absorption axis is perpendicular to the absorption axis of the first polarizing plate, and all directions (polar angle 0 ° to 80 °, azimuth angle 0 ° to 360 °). ), The x value and the y value were measured with a conoscope, and the variation in the xy color at that time was evaluated. As Δx and Δy are smaller, the rainbow unevenness is suppressed, and Δx is 0.15 or less and Δy is 0.20 or less, which is a good rainbow unevenness suppression standard.

  In addition, the four-level evaluation by silent vision is that x: the hue changes significantly with respect to the angle change, Δ: the angle range where the hue changes significantly is a range of approximately polar angle 40-60 °, ◯: The angle range in which the hue changes remarkably is in the range of approximately 40 to 50 ° polar angle, and is narrower than the above 2. A: The hue changes with respect to the angle change Almost no confirmation was made.

[Examples 1-7]
By changing the biaxial stretching conditions, various polyethylene terephthalates (PET) having in-plane retardation values (R0), thickness direction retardation values (Rth) and thicknesses as shown in Table 1 can be used as transparent resin films. Got ready.

  Using this as a base material, a zirconia particle-containing UV curable composition having a refractive index of 1.62 (manufactured by JSR Corporation, trade name “OPSTA Z7412”) was applied as an optical adjustment layer on one surface thereof to form a coating layer. Subsequently, the coating layer was irradiated with ultraviolet rays from the side on which the coating layer was formed, and an optical adjustment layer was formed so as to have a thickness of 100 nm.

Next, the PET film on which the optical adjustment layer is formed is put into a take-up sputtering apparatus, and an amorphous indium tin oxide layer (composition: SnO ₂ : 27 nm thick) is formed on the surface of the optical adjustment layer. 10 wt%) to form a transparent conductive film. In this way, a transparent conductive film was produced.

[Comparative Examples 1 to 11]
In Example 1, except that various polyethylene terephthalates (PET) having in-plane retardation values (R0), thickness direction retardation values (Rth) and thicknesses as shown in Table 1 were used as substrates, A transparent conductive film was produced under exactly the same conditions as in Example 1.

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

  As the results of Table 1 show, the transparent conductive films of Examples 1 to 7 have an in-plane retardation value of 150 nm or less and a thickness direction retardation value of 1000 nm or less, so Δx is 0.15 or less, Δy Was 0.20 or less, and it was a good result even in the silent evaluation, and sufficient rainbow unevenness suppression was possible. This means that rainbow unevenness when the display is viewed through polarized sunglasses can be suppressed. On the other hand, in Comparative Examples 1 to 11 in which the in-plane retardation value exceeds 150 nm or the thickness direction retardation value exceeds 1000 nm, at least one of Δx and Δy is large, and the result is poor even in the silent evaluation. The effect of suppressing was insufficient.

[Example 8]
In Example 1, a transparent conductive film was produced under exactly the same conditions as in Example 1 except that a PET film having a cured resin layer formed thereon was used as follows.

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

  The prepared curable resin composition containing spherical particles was applied to one surface of a PET substrate having 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 a second cured resin layer was formed so as to have a thickness of 1.0 μm. A first cured resin layer was formed on the other surface of the PET substrate by the same method except that spherical particles were not added, so that the thickness was 1.0 μm. The optical adjustment layer and the transparent conductive film were formed on the surface of the first cured resin layer.

  As a result of evaluating the rainbow unevenness of the transparent conductive film obtained, it has substantially the same Δx and Δy as in Example 1, and is also a good result in the silent evaluation, and sufficiently suppresses the rainbow unevenness. Was possible.

DESCRIPTION OF SYMBOLS 1 Protective film 2 Adhesive layer 3 2nd cured resin layer (anti-blocking layer)
4 Transparent resin film 5 First cured resin layer (hard coat layer)
6 Transparent conductive film 7 Optical adjustment layer 10 Carrier film 20 Transparent conductive film

Claims (7)

A transparent conductive film having a transparent resin film and a transparent conductive film,
The transparent resin film is a biaxially stretched polyester resin film, and has an in-plane retardation value of 150 nm or less and a thickness direction retardation value of 1000 nm or less.   The transparent conductive film of Claim 1 which has an at least 1 layer of optical adjustment layer between the said transparent resin film and the said transparent conductive film.   The transparent conductive film according to claim 1, wherein the transparent resin film has a thickness of 5 to 50 μm.   The said transparent resin film is an elongate body or a rectangular sheet, The orientation axis has an angle of 10-45 degrees with respect to a long side or a short side, The any one of Claims 1-3. Transparent conductive film.   The transparent conductive film of any one of Claims 1-4 which has a cured resin layer in the at least one surface of the said transparent resin film.   The transparent conductive film of any one of Claims 1-5 which has an adhesive layer and a protective film in this order in the surface side in which the said transparent conductive film of the said transparent resin film is not provided.   The touch panel obtained using the transparent conductive film of any one of Claims 1-6.