KR20180048801A - A transparent conductive film, and a touch panel - Google Patents

Abstract

It is an object of the present invention to provide a transparent conductive film which has sufficient material strength, low material cost, good productivity, and sufficient anti-iridescence suppression effect by using a low-phase-difference polyester as a substrate, Panel. A transparent conductive film (20) having a transparent resin film (4) and a transparent conductive film (6), wherein the transparent resin film (4) is a biaxially stretched polyester resin film and has an in- Nm or less in thickness direction retardation value and 1000 nm or less in thickness direction retardation value.

Description

A transparent conductive film, and a touch panel

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.

Recently, with the spread of PCs with tablets, smart phones, and touch panels, opportunities for handling electronic devices in the open are increasing. When a transparent conductive film using a polyethylene terephthalate (PET) film is used at that time, the in-plane retardation (generally 1000 to 2000 Nm), which causes a problem that the visibility of the display is significantly lowered.

For this reason, development of a transparent conductive film using a substrate (cyclic olefin resin or the like) having a small retardation value has been underway. However, the cyclic olefin resin or the like has such a demerit that the material strength is low and the material itself is high, and the use of low-cost and high-strength materials is being studied.

For these reasons, 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 irregularity is less likely to occur even when viewed through polarized sunglasses.

Japanese Patent Application Laid-Open No. 2004-214069

However, such a polyester film or the like having a large in-plane retardation value has such a demerit that the material strength is weak for uniaxial stretching and the film is thick to increase the retardation, resulting in an increase in material cost and a poor productivity. There are some aspects that are difficult to handle with materials.

Therefore, an object of the present invention is to provide a transparent conductive film which has sufficient material strength, low material cost, good productivity, and sufficient anti-irritation suppression effect by using a low-phase-difference polyester as a substrate, And a touch panel.

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that by using a biaxially stretched polyester resin film having an in-plane retardation value and a thickness retardation value in a predetermined range as a substrate, And 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, wherein the transparent resin film is a biaxially stretched polyester resin film having an in-plane retardation value of 150 nm or less, And the retardation value is 1000 nm or less. The various physical property values in the present invention are values measured by the method employed in Examples and the like.

In general, a biaxially stretched polyester-based resin film has a sufficient material strength and is inexpensive, but when the in-plane retardation is in the range of 1000 to 2000 nm and used in a substrate of a transparent conductive film, polarization is depolarized And the iridescence spots occur. On the other hand, when a polyester-based 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, sufficient suppression of iridescence is obtained as shown in the results of Examples .

The reason for this is not clear, but it is thought as follows. That is, when a polyester resin film having an in-plane retardation value of 150 nm or less is used, linearly polarized light is circularly polarized (including elliptically polarized light). This is because the retardation value in the thickness direction is 1000 nm or less , It is possible to suppress the change in color tone with respect to the expansion of the viewing direction, and therefore, it is considered that sufficient rainbow stain suppressing effect is obtained.

As a result, according to the transparent conductive film of the present invention, it is possible to obtain a transparent conductive film having sufficient material strength, low material cost, good productivity, Can be provided.

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 adjusting layer, the difference in the 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 can hardly be seen, The visibility is improved.

The transparent resin film preferably has a thickness of 5 to 50 mu m. A biaxially stretched polyester-based resin film having an in-plane retardation value of 150 nm or less and a thickness direction retardation value of 1000 nm or less can be produced at low cost with such a thickness in such a range.

It is preferable that the transparent resin film is an elongated body or rectangular shaped wafers and the orientation axis has an angle of 10 to 45 degrees with respect to a long side or a short side. The transparent conductive film is often used by being laminated on a quadrangular 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. Therefore, in the present invention, since the orientation axis has an angle of 10 to 45 degrees with respect to the long side or short side, it is easy to arrange the slow axis at an angle of 10 to 45 degrees with respect to the polarized light, The action of polarizing is increased, and it is easy to obtain a suppressing effect of sufficient rainbow stains.

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 and the like during transportation, and can function as an anti-blocking layer by generating irregularities on the surface.

It is preferable that the transparent resin film has a pressure-sensitive adhesive layer and a protective film in this order on the side where the transparent conductive film is not formed. The transparent conductive film of the present invention can be made into a sticky type by increasing the handling property by the protective film and constituting the protective film as a separator.

On the other hand, the touch panel of the present invention is characterized by being 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 which has sufficient material strength, is inexpensive in materials cost, has good productivity, and is capable of obtaining sufficient suppression of rainbow stains.

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

<Laminated Structure of Transparent Conductive Film>

The transparent conductive film 20 of the present invention has a transparent resin film 4 and a transparent conductive film 6 as shown in Figs. 1 to 3 and includes a transparent resin film 4 and a transparent conductive film 6 It is preferable that at least one layer of the optical adjustment layer 7 be provided. 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 and the hard coat layer 5. 4 to 6, the transparent conductive film 20 is provided on the side of the transparent resin film 4 on which the transparent conductive film 6 is not formed, the adhesive layer 2 and the protective film 1 In this case, the carrier film 10 is composed of the pressure-sensitive adhesive layer 2 and the protective film 1. In this case,

(Transparent resin film)

As the transparent resin film, a biaxially stretched polyester resin film is used. The term &quot; biaxially stretched &quot; means that the film is stretched in at least two directions, and the two-direction stretching may be simultaneous or recursive.

Examples of the polyester-based resin include a polyester-based resin selected from a polyester, a modified polyester, and blends thereof. As the polyester, for example, those 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 aromatic dicarboxylic acids such as 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, dimethyl malonic acid, succinic acid, glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, Sebacic acid, fumaric acid, maleic acid, itaconic acid, thiodipropionic acid and diglycolic acid. Examples of the alicyclic dicarboxylic acid include 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4- Cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, and adamantanedicarboxylic acid. The carboxylic acid component may be a derivative such as an ester, a chloride or an acid anhydride, and examples thereof include dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, terephthalic acid Dimethyl and terephthalic acid diphenyl. The carboxylic acid component may be used alone, or two or more kinds may be used in combination.

Representative examples of the polyol component include divalent alcohols. Examples of dihydric alcohols include aliphatic diols, alicyclic diols and aromatic diols. The aliphatic diol includes, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4- Propylene diol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl- Butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexane Diols. The alicyclic diols include, for example, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol , And 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'- (2, 6-cyclophenol) 2,5-naphthalene, 4,4'-isopropylidene phenol, 4,4'-isopropylidenebis Diol and p-xylene diol. The polyol component may be used alone or in combination of two or more.

Preferred examples of the carboxylic acid component include terephthalic acid, isophthalic acid and 2,5-naphthalenedicarboxylic acid. Preferable examples of the polyol component 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 a combination of the above-mentioned monomers. Therefore, preferable examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexylene terephthalate, and copolymers thereof , Blends and modified bodies.

By using such a polyester resin and further applying a manufacturing method including a tilt stretching, it is possible to obtain a transparent resin film having a desired in-plane retardation and direction of the orientation axis and having better axial precision.

In the present invention, the polyester resin may be a modified PET containing a repeating unit derived from cyclohexane dimethanol. In this case, the proportion of cyclohexane dimethanol in the polyol component is preferably more than 0 mol% and 10 mol% or less, more preferably 0 mol% or more and 3 mol% or less. The polyester resin may be a modified PET containing a repeating unit derived from isophthalic acid. In this case, the ratio of isophthalic acid in the carboxylic acid component is preferably more than 0 mol% and 20 mol% or less, more preferably 0 mol% or more and 10 mol% or less. Needless to say, these embodiments may be combined.

The transparent resin film is produced as a biaxially stretched elongated film (elongated body). As used herein, the term &quot; elongated shape &quot; refers to a thin and long 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, and more preferably 100 or more. In one embodiment, the transparent resin film is an elongated body rolled in the form of a roll, and in another embodiment, the transparent resin film is a rectangular body.

The transparent resin film preferably has an orientation axis at an angle of 10 to 45 degrees with respect to a long side or a short side, more preferably an angle of 20 to 45 degrees, and most preferably an angle of 30 to 45 degrees. In the transparent conductive film of the present invention, the orientation axis of the transparent resin film is preferably arranged at an angle of 10 to 80 degrees with respect to the vibration direction of the linearly polarized light emitted from the display device, More preferably, 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 in the range of 38 ° to 52 °, more preferably in the range of 43 ° to 47 ° with respect to the longitudinal direction over the entire width direction of the film. Deg., And more preferably, the slow axis direction is at an angle of about 45 DEG with respect to the long direction. By applying the manufacturing method including the tilt stretching, the transparent resin film can obtain a transparent resin film having the slow axis in the tilting direction with excellent axial precision.

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

Herein, the in-plane retardation R0 is the in-plane retardation of the film measured at a wavelength of 590 nm at 23 deg. R0 is obtained by the formula: R0 = (nx-ny) xd, where d (nm) is the thickness of the film. Here, nx is a refractive index in the direction in which the in-plane refractive index is the maximum (i.e., the slow axis direction), and ny is the refractive index in the plane perpendicular to the slow axis.

The retardation in the thickness direction (Rth) of the transparent resin film in the thickness direction is 1000 nm or less, preferably 350 to 950 nm, more preferably 400 to 900 nm, from the viewpoint of achieving a sufficient suppressing effect of rainbow stains and obtaining sufficient strength. Nm.

Here, the retardation in the thickness direction (Rth) is the retardation in the thickness direction of the film measured at a wavelength of 590 nm at 23 캜. Rth is obtained by the formula: Rth = (nx - nz) xd, 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 the maximum (i.e., the slow axis direction), and nz is the refractive index in the thickness direction.

In the present invention, the ratio of retardation (R0 / Rth) is also important. From the viewpoint of further enhancing the suppression effect of rainbow stains and obtaining sufficient strength, the retardation ratio (R0 / Rth) is preferably 0.01 to 0.5, More preferably 0.02 to 0.47, and still more preferably 0.04 to 0.45.

The transparent resin film is preferably 2.0% or less in dimensional shrinkage percentage after heating at 80 DEG C for 240 hours, and more preferably 1.0% or less.

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

The thickness of the transparent resin film is preferably 5 to 50 占 퐉, more preferably 7 占 퐉 to 40 占 퐉, and more preferably 10 to 30 占 퐉, from the viewpoint of obtaining the retardation in the in- Is more preferable.

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

The weight average molecular weight of the polyester-based resin is preferably 10,000 to 100,000, and more preferably 15,000 to 50,000. With such a weight average molecular weight, it is easy to handle during molding, and a film having excellent mechanical strength can be obtained.

The polyester-based resin can be formed into a film by any suitable method. The obtained polyester-based resin film can be biaxially stretched in a longitudinal and transverse direction by biaxial stretching. At that time, as disclosed in Japanese Laid-Open Patent Publication No. 2015-72376, a transparent resin film having an orientation axis in a tilting direction can be preferably obtained by providing it to a manufacturing method including a tilt elongation.

That is, the left and right ends of the film to be stretched are gripped by the left and right clips of variable pitch type in which the clip pitch in the longitudinal direction changes (step A: gripping step); Preheating the film (Process B: preheating process); The clip pitch of the right and left clips is independently varied to tilt and stretch the film (Step C: stretching step); Crystallizing the film by heat treatment in a state where the clip pitch of the left and right clips is kept constant as needed (Process D: crystallization process); And releasing the clip holding the film (Process E: releasing step), the transparent resin film used in the present invention can be preferably manufactured by a manufacturing method including inclination stretching.

The surface of the transparent resin film is subjected to an etching treatment or undercoating treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion and oxidation in advance to form an optical adjustment layer, a cured resin layer, The adhesion with the conductive film or the like may be improved. Before the formation of the optical adjustment layer or the like, the surface of the transparent resin film may be damped or cleaned by solvent cleaning or ultrasonic cleaning as necessary.

(Cured resin layer)

The cured resin layer includes a first cured resin layer formed on one side of the first main surface of the transparent resin film and a second cured resin layer formed on the second main side opposite to the first cured resin layer. Since the transparent resin film is prone to scratches in each process such as formation of a transparent conductive film, patterning of a transparent conductive film, mounting on an electronic device, and the like, the first cured resin layer and the second It is preferable to form a cured resin layer.

The cured resin layer is a layer obtained by curing the curable resin. As the resin to be used, a thermosetting resin, an ultraviolet-curable resin, an electron beam-curable resin, a two-liquid mixed resin, and the like can be used as the resin having sufficient strength as a film after formation of a cured resin layer and having transparency without particular limitation . Among them, an ultraviolet curable resin which can efficiently form a cured resin layer by a simple processing operation in a curing treatment by ultraviolet irradiation is preferable.

Examples of the ultraviolet curable resin include various types such as a polyester type, an acrylic type, a urethane type, an amide type, a silicone type and an epoxy type, and include ultraviolet curable type 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, it is possible to form ridges on the surface of the cured resin layer, and the anti-blocking property can be preferably imparted to the transparent conductive film.

As the above-mentioned particles, those having transparency such as various metal oxides, glass, and plastic can be used without particular limitation. For example, inorganic particles such as silica, alumina, titania, zirconia and calcium oxide, and various polymers such as polymethyl methacrylate, polystyrene, polyurethane, acrylic resin, acryl-styrene copolymer, benzoguanamine, melamine and polycarbonate Based organic particles and silicon-based particles, which are crosslinked or uncrosslinked. One or more of these particles can be appropriately selected and used, but organic particles are preferred. As the organic particles, an acrylic resin is preferable from the viewpoint of the refractive index.

The optimum particle diameter of the particles can be suitably set in consideration of the relationship between the protrusion of the ridge of the cured resin layer and the thickness of the flat region other than the ridge, and the like, and is not particularly limited. From the viewpoint of sufficiently imparting blocking resistance to the transparent conductive film and sufficiently suppressing the rise of haze, the particle size of the particles is preferably from 0.1 to 3 mu m, more preferably from 0.5 to 2.5 mu m. In the present specification, the term &quot; minimum particle diameter &quot; refers to particle diameter indicating the maximum value of the particle distribution, and is measured under a predetermined condition (Sheath Solution: ethyl acetate, measurement mode: HPF measurement, measurement method: total count). The sample to be measured is prepared by diluting the particles with 1.0% by weight of ethyl acetate and uniformly dispersing them 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, and even more preferably 0.1 to 0.2 part by weight based on 100 parts by weight of the solid content of the resin composition. If the content of the particles in the cured resin layer is small, it is likely that ridges sufficient to impart anti-blocking property and slippery property to the surface of the cured resin layer become difficult to be formed. On the other hand, if the content of the particles is too large, the haze of the transparent conductive film tends to increase due to light scattering caused by the particles, and the visibility tends to decrease. If the content of the particles is too large, streaks may be generated at the time of forming the cured resin layer (at the time of applying the solution), thereby impairing the visibility and uneven electrical characteristics of the transparent conductive film.

The cured resin layer is formed by applying a resin composition containing each curable resin and particles, a crosslinking agent, an initiator, a sensitizer, and the like as needed, on a transparent resin film, and when the resin composition contains a solvent, And curing it by application of heat, active energy rays or both. The heat may be a known means such as an air circulating oven or an IR heater, but is not limited to these methods. Examples of the active energy ray include, but are not limited to, ultraviolet ray, electron ray, gamma ray and the like.

The cured resin layer can be formed 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, crystallization time of the transparent conductive film can be shortened if the surface of the cured resin layer as a ground layer is smooth. From this viewpoint, it is preferable that the cured resin layer is formed by a wet coating method.

The thickness of the cured resin layer is preferably 0.5 탆 to 5 탆, more preferably 0.7 탆 to 3 탆, and most preferably 0.8 탆 to 2 탆. When the thickness of the cured resin layer is within the above range, it is possible to prevent film wrinkles in prevention of scratches and curing shrinkage of the cured resin layer, thereby preventing the visibility of the touch panel and the like from deteriorating.

(Transparent conductive film)

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

Although the thickness of the transparent conductive film is not particularly limited, it is preferable that the thickness of the transparent conductive film is 10 nm or more in order to form a continuous film having good conductivity with a surface resistance of 1 x 10 &lt; ³ &gt; If the film thickness is excessively increased, transparency deteriorates. Therefore, the thickness is preferably 15 to 35 nm, more preferably 20 to 30 nm. If the thickness of the transparent conductive film is less than 10 nm, the electrical resistance of the film surface becomes high and it becomes difficult to form a continuous film. If the thickness of the transparent conductive film exceeds 35 nm, the transparency may be lowered.

The method of forming the transparent conductive film is not particularly limited, and conventionally known methods can be employed. Specifically, for example, a dry process such as a vacuum deposition method, a sputtering method, and an ion plating method can be exemplified. An appropriate method may be employed depending on the required film thickness. When a transparent conductive film is formed on the first cured resin layer by a dry process such as a sputtering method, the surface of the transparent conductive film substantially retains the surface shape of the first cured resin layer as the underlayer . Therefore, when ridges are present in the first cured resin layer, anti-blocking properties and slipperiness can be favorably imparted to the surface of the transparent conductive film.

The transparent conductive film can be crystallized by a thermal annealing treatment (for example, at 80 to 150 DEG C for about 30 to 90 minutes in an atmospheric environment) if necessary. By crystallizing the transparent conductive film, the transparency and durability of the transparent conductive film are improved in addition to the low resistance. The means for making the amorphous transparent conductive film into crystalline is not particularly limited, but an air circulating oven or IR heater is used.

For the definition of "crystalline", a transparent conductive film having a transparent conductive film formed on a transparent resin film was immersed in hydrochloric acid having a concentration of 5% by weight at 20 ° C. for 15 minutes, washed with water and dried, , And when the resistance between terminals is not more than 10 k ?, it is assumed that the telephone to the crystalline of the ITO film is completed.

The transparent conductive film may be patterned by etching or the like. The patterning of the transparent conductive film can be carried out by using a conventionally known technique of photolithography. As the etchant, 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 in a capacitive touch panel or a matrix type resistive touch panel, it is preferable that the transparent conductive film is patterned in a stripe shape. Further, when the transparent conductive film is patterned by etching, if crystallization of the transparent conductive film is performed first, patterning by etching may become difficult. Therefore, the annealing of the transparent conductive film is preferably performed after patterning the transparent conductive film.

The transparent conductive film may be amorphous or crystalline when laminating a carrier film to be described later. For example, after a transparent conductive film is bonded to a transparent conductive film having an amorphous state with a pressure-sensitive adhesive layer interposed therebetween, the film can be annealed to be crystalline.

The transparent conductive film may include metal nanowires. The metal nanowire refers to a conductive material whose material is metal, shape is needle-like or thread-like, and has a diameter of nanometer size. The metal nanowires may be linear or curved. When a transparent conductive layer composed of metal nanowires is used, the metal nanowires are in the form of a mesh, so that even a small amount of metal nanowires can form a good electrical conduction path and a transparent conductive film having a small electrical resistance can be obtained. Further, since the metal nanowires are in the form of meshes, openings are formed in the gaps of the mesh, and a transparent conductive film having a high light transmittance can be obtained.

As the metal constituting the metal nanowire, any appropriate metal may be used as long as it is a metal having high conductivity. Examples of the metal constituting the metal nanowire include silver, gold, copper, and nickel. In addition, a material obtained by subjecting these metals to a plating treatment (for example, a gold plating treatment) may be used. Among them, silver is preferably copper or gold, and more preferably silver, from the viewpoint of conductivity.

(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 difference in transmittance difference or reflectance between the pattern portion where the pattern remains and the opening portion where the pattern is not formed can be reduced, And is used to obtain a conductive film.

The refractive index of the optical adjusting layer is preferably 1.5 to 1.8, more preferably 1.51 to 1.78, and further preferably 1.52 to 1.75. Thereby, the difference in transmittance and the difference in reflectance can be reduced, and a transparent conductive film having excellent 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. Material in forming an 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, ZnO, ZnS, and SiO _x (x is 1.5 or more and less than 2), organic materials such as acrylic resin, epoxy resin, urethane resin, melamine resin, alkyd resin and siloxane polymer. Particularly, as the organic material, it is preferable to use a thermosetting resin comprising a mixture of a melamine resin, an alkyd resin and an organosilane condensate. 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 vapor 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 nano-particles in the optical adjustment layer is preferably 0.1 wt% to 90 wt%. The average particle diameter of the nano-particles used in the optical adjustment layer is preferably in the range of 1 nm to 500 nm, more preferably in the range of 5 nm to 300 nm as described above. The content of the nano-particles in the optical adjusting layer is more preferably 10 wt% to 80 wt%, and still more preferably 20 wt% to 70 wt%. By containing nanoparticles in the optical adjustment layer, it is possible to easily adjust the refractive index of the optical adjustment layer itself.

Examples of the inorganic oxide for forming the nano-particle include fine particles such as silicon oxide (silica), hollow nanosilica, 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 singly or in combination of two or more kinds.

The thickness of the optical adjusting layer is preferably from 10 nm to 200 nm, more preferably from 20 nm to 150 nm, even more preferably from 30 nm to 130 nm. If the thickness of the optical adjustment layer is excessively small, it is difficult to form a continuous coating. In addition, if the thickness of the optical adjustment layer is excessively large, the transparency of the transparent conductive film tends to be lowered or cracks tend to occur.

(Metal layer, metal wiring)

In the present invention, it is also possible to form a metal layer or a metal wiring on the transparent conductive film. The metal wiring can be formed by forming a metal layer on the transparent conductive film and then etching, but it is preferable that the metal wiring is formed by using a photosensitive metal paste as follows. That is, after the transparent conductive film is patterned, the metal wiring is formed by coating a photosensitive conductive paste described later on the transparent resin film or the transparent conductive film to form a photosensitive metal paste layer, A photosensitive metal paste layer is exposed through a mask, and then a development is performed to form a pattern, followed by a drying step. That is, it is possible to form a metal wiring pattern by a known photolithography method or the like.

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

The conductive particles other than the metal powder may be metal coated resin particles in which the surface of the resin particle is coated with a metal. As the material of the resin particles, the above-mentioned particles are contained, 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 a 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 diameter of 0.1 mu m to 1.4 mu m, a 90% particle diameter of 1 to 2 mu m, and a top size of 4.5 mu m or less. The composition of the glass frit is not particularly limited, but it is preferable that Bi ₂ O ₃ is blended in the range of 30 wt% to 70 wt% with respect to the whole glass frit. The oxides that may be contained in other than Bi ₂ O ₃ may include SiO ₂ , B ₂ O ₃ , ZrO ₂ , and Al ₂ O ₃ . It is preferable that the glass frit is an alkali-free glass frit substantially containing no Na ₂ O, K ₂ O, or Li ₂ O.

The photosensitive organic component preferably contains a photosensitive polymer and / or a photosensitive monomer. Examples of the photosensitive polymer include a polymer having a carbon-carbon double bond-containing polymer such as methyl (meth) acrylate and ethyl (meth) acrylate, or a polymer having a polymerizable unsaturated group at the side chain or molecular end of an acrylic resin A reactive group is added, and the like are preferably used. Preferred examples of the photoreactive group include ethylenic unsaturated groups such as vinyl, allyl, acryl, and methacryl 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,? -Methacryloxypropyltrimethoxysilane and 1-vinyl-2-pyrrolidone, One or more of them may be used.

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 from the viewpoint of light sensitivity, more preferably 10 to 30 parts by weight. In the photosensitive conductive paste of the present invention, a photo polymerization initiator, a sensitizer, a polymerization inhibitor, and an organic solvent are preferably used, if necessary.

The thickness of the metal layer is not particularly limited. For example, when a part of the surface of the metal layer is removed by etching or the like to form a pattern wiring, 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 탆, more preferably 0.05 to 100 탆. When the thickness of the metal layer is within the above range, the resistance of the pattern wiring is not excessively increased and the power consumption of the device is not increased. In addition, the production efficiency of the film formation of the metal layer increases, the amount of heat accumulated 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 formed on a non- For example, a peripheral portion. The transparent conductive film may be used in a non-display portion, and in this case, a 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 a pressure-sensitive adhesive layer on at least one side of the protective film. The carrier film forms a transparent conductive film by bonding a second main surface side of the transparent conductive film and a peelable transparent conductive film via a pressure-sensitive adhesive layer. When the carrier film is peeled from the transparent conductive film, the pressure-sensitive adhesive layer may be peeled together with the protective film, or only the protective film may be peeled off.

(Protective film)

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

Examples of the crystalline resin include a polyester-based resin such as polyethylene terephthalate and polyethylene naphthalate; and a polyolefin-based resin such as polyethylene and polypropylene. A polyester-based resin is preferable.

Examples of the amorphous resin include a cycloolefin resin and a polycarbonate resin. From the viewpoints of excellent light transmission, scratch resistance and water resistance, and good mechanical properties, a polycarbonate resin is preferable. Examples of the polycarbonate resin include an aliphatic polycarbonate, an aromatic polycarbonate, an aliphatic-aromatic polycarbonate, and the like.

As with the transparent resin film, the surface of the protective film is subjected to an etching treatment or a priming treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion and oxidation in advance to improve the adhesion with the pressure- . Before the pressure-sensitive adhesive layer is formed, the surface of the protective film may be damped and cleaned by solvent cleaning or ultrasonic cleaning as necessary.

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

(Pressure-sensitive adhesive layer)

The pressure-sensitive adhesive layer can be used without particular limitation as long as it has transparency. Specific examples thereof include polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy based, fluorine based, natural rubber, Rubber, or the like as a base polymer can be appropriately selected and used. In particular, an acrylic pressure-sensitive adhesive is preferably used because it has excellent optical transparency, exhibits adhesive properties such as appropriate wettability, cohesiveness and adhesiveness, and is also excellent in weather resistance and heat resistance.

The method of forming the pressure-sensitive adhesive layer is not particularly limited, and a method of applying a pressure-sensitive adhesive composition to a release liner, drying and then transferring the pressure-sensitive adhesive composition onto a base film (transfer method), a method of directly applying a pressure- ) Or a method by coextrusion. Further, a tackifier, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a silane coupling agent and the like may be suitably used for the pressure-sensitive adhesive, if necessary. The preferable thickness of the pressure-sensitive adhesive layer is 5 占 퐉 to 100 占 퐉, more preferably 10 占 퐉 to 50 占 퐉, and still more preferably 15 占 퐉 to 35 占 퐉.

&Lt; Properties of transparent conductive film &

The transparent conductive film of the present invention preferably has deviation Δx in the xy coloring of the evaluation of rainbow stains in the examples of not more than 0.15 and Δy of not more than 0.20, more preferably Δy of not more than 0.13 and Δy of not more than 0.17 Do.

In order to accomplish this, when the transparent resin film is used singly, it is preferable that Δx is not more than 0.15 and Δy is not more than 0.20, and Δx is not more than 0.13 and Δy is not more than 0.17 Do.

<Touch panel>

The transparent conductive film obtained by peeling the carrier film or the protective film from the transparent conductive film can be preferably applied as a transparent electrode of an electronic device such as a touch panel such as a capacitive type or a resistive film type.

At the time of forming the touch panel, other materials such as glass or polymer film can be bonded to one or both of the main surfaces of the above-mentioned transparent conductive film with a transparent pressure-sensitive adhesive layer interposed therebetween. For example, a laminate in which a transparent substrate is bonded to the surface of the transparent conductive film on the side where the transparent conductive film is not formed, via a transparent pressure-sensitive adhesive layer, may be formed. The transparent substrate may be a single substrate film or a laminate of two or more substrates (for example, a substrate laminated with a transparent pressure-sensitive adhesive layer interposed therebetween). The hard coat layer may be formed on the outer surface of the transparent substrate to be bonded to the transparent conductive film. The pressure-sensitive adhesive layer used for bonding the transparent conductive film to the substrate can be used without particular limitation as long as it has transparency as described above.

When the transparent conductive film of the present invention is used for the formation of a touch panel, by using a polyester having a low phase difference as a substrate, it is possible to obtain a film having sufficient material strength, low material cost, good productivity, A touch panel having a transparent conductive film can be provided. And can be used as a shielding application for shielding electromagnetic waves and noise emitted from electronic devices, other than the use of a touch panel.

Example

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples. The physical properties and the like in the examples and the like were measured as follows.

(Phase difference)

The in-plane retardation of the transparent resin film was measured at a measurement wavelength of 590 nm under an environment of 23 캜 using a polarization / phase difference measurement system (AxoScan, manufactured by Axometrics). Similarly, the phase difference was measured when the film was inclined by 40 DEG with the slow axis direction and the fast axis direction as rotation centers. The order of the measured values of the retardation was determined so as to coincide with the wavelength dispersion of the retardation of the previously obtained transparent resin film. From these measured values, the in-plane retardation value (R0) and the thickness direction retardation value (Rth) of the transparent resin film were calculated.

(Measurement of thickness)

With respect to the thickness having a thickness of 1 占 퐉 or more, the measurement was carried out with a micro-gauge thickness meter (manufactured by Mitsutoyo Corporation). The thickness of less than 1 mu m and the thickness of the optical adjustment layer were measured with an instant multi-photometry system (MCPD2000 manufactured by OTSUKA ELECTRONICS CO., LTD.). The thickness of the nano-size such as the thickness of the ITO film and the like was measured by using FB-2000A (manufactured by Hitachi High-Technologies Corporation), and cross-sectional TEM observation was performed using HF-2000 (manufactured by Hitachi High Technologies Corporation) And the film thickness was measured. The evaluation results are shown in Table 1.

(Evaluation of rainbow stains)

As a method of evaluating the rainbow stains, a deviation evaluation in the xy coloring and a four-step evaluation (⊚ to Х) by implication were conducted.

The deviation in the xy color was evaluated by using a Konoskop (Conronic, manufactured by Autronic-Melchers), and a commercially available polarizer was disposed on a high-luminance backlight. A transparent conductive film was placed on the absorption axis of the first polarizing plate such that the direction of the slow axis of the substrate (that is, the alignment axis) was 45 °. On the transparent conductive film, , The second polarizing plate is further placed on the second polarizer plate so that the absorption axis is orthogonal so that the x value and the y value are measured from the omnidirectional angle (0 deg. To 80 deg. Polarizations and 0 deg. To 360 deg. Azimuthal angle) The deviation in the color was evaluated. The smaller the values of? X and? Y are, the less iridescent speckles are suppressed. The? X is 0.15 or less and the? Y is 0.20 or less.

In the four-step evaluation by implication, the hue significantly changes with respect to the angular change, and the angular range in which the hue changes significantly is generally in the range of 40 to 60 degrees from the polar angle, , &Amp; cir &amp;: The angle range in which the hue changes remarkably is generally in the range of 40 to 50 DEG polar angles, narrower than the above 2, and &amp;

[Examples 1 to 7]

Various polyethylene terephthalate (PET) films having an in-plane retardation value (R0) and a thickness direction retardation value (Rth) and thickness as shown in Table 1 were prepared as a transparent resin film by changing the conditions of biaxial stretching.

An ultraviolet curable composition containing zirconia particles having a refractive index of 1.62 (manufactured by JSR Corporation, trade name &quot; Obstar Z7412 &quot;) as an optical adjustment layer was coated on one side thereof to form a coating layer. Subsequently, the coating layer was irradiated with ultraviolet rays on the side where 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 was formed was placed in a winding type sputtering apparatus, and an amorphous indium tin oxide layer (composition: SnO ₂ : 10 wt%) having a thickness of 27 nm was deposited on the surface of the optical adjustment layer To form a transparent conductive film. Thus, a transparent conductive film was produced.

[Comparative Examples 1 to 11]

Examples 1 and 2 were obtained in the same manner as in Example 1 except that various polyethylene terephthalate (PET) having in-plane retardation value (R0) and thickness direction retardation value (Rth) Under the completely same conditions, a transparent conductive film was produced.

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

As shown in the results of Table 1, the transparent conductive films of Examples 1 to 7 have an in-plane retardation value of 150 nm or less and a retardation value in the thickness direction of 1000 nm or less, so? X is 0.15 or less and? Y is 0.20 or less , And also good results in the implied evaluation, and sufficient rainbow stain suppression was possible. This means that rainbow stains are suppressed when the display is viewed through polarized sunglasses. 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? X and? Y was large and the result was worse even in the implied evaluation, Was insufficient.

[Example 8]

A transparent conductive film was produced in the same manner as in Example 1 except that a cured resin layer was formed on the PET film in the following manner.

First, 100 parts by weight of an ultraviolet ray-curable resin composition (trade name "UNIDIC (registered trademark) RS29-120", trade name, manufactured by DIC) and acrylic spherical particles (trade name "MX-180TA" And 0.2 part by weight of a curable resin composition containing spherical particles.

The curable resin composition containing the prepared spherical particles was coated on one side of the PET base material with a thickness of 50 占 퐉 to form a coating layer. Then, the coating layer was irradiated with ultraviolet rays at the side where the coating layer was formed, and a second cured resin layer was formed so as to have a thickness of 1.0 탆. A first cured resin layer was formed on the other surface of the PET substrate so that the thickness was 1.0 占 퐉, in the same manner as in the above, except that spherical particles were not added to the above. The formation of the optical adjusting layer and the transparent conductive film was performed on the surface of the first cured resin layer.

As a result of evaluating the iridescent smear of the obtained transparent conductive film, it was found that it had substantially the same? X and? Y as in Example 1, and the iridescent smear evaluation was satisfactory and sufficient iridescent smear suppression was possible.

1: Protective film
2: Pressure-sensitive adhesive layer
3: Second 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 having an in-plane retardation value of 150 nm or less and a retardation value in the thickness direction of 350 to 1000 nm. The method according to claim 1,
And at least one optical adjustment layer is provided between the transparent resin film and the transparent conductive film. 3. The method according to claim 1 or 2,
Wherein the transparent resin film has a thickness of 5 to 50 占 퐉. 4. The method according to any one of claims 1 to 3,
Wherein the transparent resin film is an elongated body or a rectangular shaped sheet, and the orientation axis has an angle of 10 to 45 degrees with respect to a long side or a short side. 5. The method according to any one of claims 1 to 4,
Wherein the transparent resin film has a cured resin layer on at least one surface of the transparent resin film. 6. The method according to any one of claims 1 to 5,
Wherein the transparent resin film has a pressure-sensitive adhesive layer and a protective film in this order on the side where the transparent conductive film is not formed. A touch panel obtained using the transparent conductive film according to any one of claims 1 to 6.

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