JP2007134293A - Transparent conductive film and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive film excellent in transparency and abrasion resistant property, with less change of resistance even at high temperature of 90°C or high temperature/high humidity of 85°C/85%. <P>SOLUTION: The transparent conductive film is constituted by forming a conductive film on a base body containing at least polyethylene naphthalate film. A total light beam transmission rate of the base body is 88% or higher, and contraction rate in longitudinal direction (MD) and lateral direction (TD) of the transparent conductive film on the base body after thermal decomposition at 50°C for 30 minutes is 0.3% or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transparent conductive film used for a display such as a touch panel and a manufacturing method thereof. Specifically, by using a specific plastic film, it is excellent in heat resistance, environmental resistance at high temperature and high humidity, and is a transparent conductive film excellent in transparency and sliding resistance, which are necessary characteristics as a touch panel. It relates to the manufacturing method.

  The transparent conductive film is used as an electrode of an optical display such as an electrode of a touch panel (hereinafter sometimes referred to as TP), an electrode of a liquid crystal display, an electrode of an electroluminescence display. For example, in a resistive film type touch panel, generally, a transparent conductive glass plate and a polyethylene terephthalate film (hereinafter referred to as PET film) to which indium tin oxide (hereinafter sometimes referred to as ITO) is attached by a method such as sputtering are used. A transparent conductive film in which ITO is attached to a plastic film by a method such as sputtering is used as an electrode, facing each other through a spacer.

  2. Description of the Related Art A touch panel that is arranged on a display device such as a CRT or an LCD and can input data, instructions, and commands by pressing with a finger or a pen while watching the display is widely used.

A transparent conductive film used as an electrode for TP is generally manufactured by attaching a transparent conductive material such as ITO (indium tin oxide) to a PET film by a technique such as sputtering. Yes. However, GPS TPs mounted on automobiles that have become widespread in recent years are required to have characteristics that do not change even in harsh environments such as heat, cold, and high humidity. Therefore, in the transparent conductive film using a PET film, since the glass transition temperature of the PET film is 70 ° C. or less, the required high temperature and high temperature and high humidity cannot be satisfied. In many cases, a thin glass plate having a thickness of about 0.2 mm is used. However, this thin glass plate has a problem that it is easily broken during processing and use and is expensive.
In addition, a transparent conductive film using a heat-resistant plastic film has been studied. For example, as a plastic film, a norbornene-based film (trade name: Arton) of JSR Corporation, a norbornene-based film (trade name: ZEONOR and ZEONEX) of ZEON CORPORATION, polycarbonate (PC), and polyethersulfone (PES) are available. Can be mentioned.
However, norbornene-based and PC films are thermoplastic films in the severe high-temperature and high-humidity and high-temperature environments required for automobile TP after ITO is deposited. There was a problem of warping. In addition, the heat resistance is not always sufficient, and the ITO peels off from the plastic surface at high temperature or high temperature and high humidity, or the resistance value is greatly increased due to the occurrence of fine cracks. There was a problem. In addition, when used as a TP, there is a problem that a large increase in resistance value occurs even when a finger or a pen is used for input.
The PES film also had the same problem, although the heat resistance problem was small compared to the above film. Further, PES has a problem in the characteristics of the material itself as a film for TP that is colored yellow and has low transmittance. In addition, there is a problem of being expensive.
Polyethylene naphthalate film (hereinafter referred to as PEN film) is sold as Teonex of Teijin Limited or SKYNEX of SKC of South Korea. Its total light transmittance is as low as about 82% and haze value is about 14%. In addition, the transparent conductive film substrate for TP has not been put into practical use because of unsatisfactory optical characteristics. In recent years, PEN films with transparency improved to about 88% have been developed. However, when TP is manufactured, there is a problem that ITO is peeled off at the interface between the PEN film and ITO, or fine cracks are generated in the ITO. was there.
In addition, when used as an electrode for TP, the PEN film expands or is exposed to high temperature, low temperature, high temperature and high humidity in order to rub or push the surface of the transparent conductive film with a pen or a finger. When shrunk, peeling from the ITO film and fine cracks are further increased, resulting in a significant increase in resistance value, resulting in a fatal defect as a TP electrode. In other words, there was a problem of poor sliding resistance.

  On the other hand, there is an attempt to make the ITO dense and high strength in order to improve the sliding characteristics. (For example, refer to Patent Document 1) In this method, amorphous ITO is applied to a PET film by a sputtering method, and then annealing is performed at a temperature of about 150 ° C. for several hours to several tens of hours. Crystallized ITO. The transparent conductive film to which crystallized ITO is attached is superior in sliding characteristics to the transparent conductive film to which amorphous ITO is attached, but is not satisfactory as a pen input TP. Met. In addition, since annealing for a long time is required, there is a problem that transparency is impaired, yellow is colored, and expensive. Also, after the ITO layer is formed on the PET film, annealing treatment is performed at a temperature around 150 ° C., so that the final heat shrinkage rate of the ITO film in the MD and TD directions is 0.3%. In such a conductive film, the ITO layer may be peeled off from the PET film due to repeated sliding and environmental changes when used as TP, and in some cases, fine cracks are increased, There is a problem that the resistance value is not increased or the resistance value is significantly increased and the TP electrode does not function.

  As described above, various studies have been made on transparent conductive films that are transparent and have excellent heat resistance, stability at high temperatures and high humidity, and excellent sliding resistance. Is not always satisfied, but the structure is complicated and the manufacturing process is complicated, which causes other defects such as sacrificing other optical characteristics and increasing costs. It was.

  Furthermore, when used as an electrode for TP, anti-glare coat (AG coat) for improving visibility, anti-Newton ring property, and prevention of scratches on the touch surface are also required. There has been a strong demand for an ITO film having both of the above.

  JP-A-8-064034

  An object of the present invention is to solve all the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a transparent conductive film excellent in transparency, having a small change in resistance value even at a high temperature of 90 ° C. and a high temperature and high humidity of 85 ° C. and 85%, and having excellent sliding resistance. It is said. Moreover, it aims at providing the structure of the transparent conductive film which was excellent in visibility and suppressed the damage of a touch surface, having said characteristic.

The inventors of the present invention have found that peeling of the conductive film and fine cracks that occur during production of the transparent conductive film using the conventional plastic film are mainly caused by the film and the conductive film that is an inorganic substance in the heating process during production. It was assumed that it occurs due to the difference in expansion coefficient. Furthermore, the variation in resistance value after being used as TP, and slidability are also related to stress due to the difference between the fine cracks and the expansion coefficient, particularly in a high temperature environment or a high temperature and high humidity environment, As the plastic film repeatedly expands and contracts, the cracks increase, so that it is assumed that the resistance value fluctuates and the slidability deteriorates significantly. That is, in the case of the conventional PEN film with improved transparency, the shrinkage after holding at 150 ° C. for 30 minutes is relatively 0.5 to 0.6% in the flow direction (MD) at the time of film production. In order to greatly shrink, the transparent conductive film based on the PEN film needs to be cured with a silver paste at a temperature of around 150 ° C. at the time of TP production. At this point, the film is biaxially stretched. Since the PEN film contracted and ITO, which is an inorganic substance, hardly contracted, it was considered that peeling or cracking occurred.
In addition, the problem of a decrease in the resistance value of the crystallized ITO under high temperature and high humidity is that the ITO layer itself becomes crystalline and high in strength, but the thermal contraction rate of the substrate remains large and the crystallization is The heat treatment of about 150 ° C is performed, and due to the large shrinkage of the PEN film and the non-shrinkage of the ITO, large stress remains at the interface between the PEN film and the ITO, causing the ITO layer to peel off or crack I thought it was one.

  As a result of intensive studies to solve the above-mentioned problems, it is a transparent conductive film formed by forming a conductive film on a substrate including at least a polyethylene naphthalate film, and the total light transmittance of the substrate is 88% or more. The transparent conductive film in which the shrinkage in the longitudinal direction (MD) and the transverse direction (TD) after heating at 150 ° C. for 30 minutes is 0.3% or less is transparent, environmental resistance, The inventors have found that it has both mobility and is excellent, and has reached the present invention. Moreover, the structure of the transparent conductive film which was excellent in visibility and suppressed the damage was also discovered.

That is, the means for solving the above problems are as follows.
<1> A transparent conductive film formed by forming a conductive film on a substrate containing at least a polyethylene naphthalate film, wherein the substrate has a total light transmittance of 88% or more and is 30 minutes at 150 ° C. of the substrate. A transparent conductive film, wherein the shrinkage in the longitudinal direction (MD) and the transverse direction (TD) after heating is 0.3% or less.
<2> The transparent conductive film according to <1>, wherein the substrate has a cured layer on at least one surface of the polyethylene naphthalate film.
<3> The transparent conductive film according to <1>, wherein the substrate has a cured layer in which a thermally crosslinkable substance is cured and formed as a cured layer.
<4> The transparent conductive film according to <2> or <3>, wherein the substrate has a cured layer in which a crosslinkable substance by light or electron beam is cured and formed.
<5> The transparent conductive film according to <4>, wherein the substrate has a cured layer on which a crosslinkable substance by light or electron beam is cured and formed on both sides of the polyethylene naphthalate film.
<6> The transparent conductive film according to any one of <1> to <5>, wherein the conductive film is ITO (indium tin oxide).
<7> A substrate having at least a polyethylene naphthalate film and a cured layer on which a crosslinkable substance is cured and formed, the longitudinal direction (MD) and the transverse direction (TD) after heating at 150 ° C. for 30 minutes A substrate preparation step of preparing a substrate having a shrinkage ratio of 0.3% or less, and a conductive film attachment step of attaching a conductive film to the substrate prepared in the substrate preparation step, the substrate preparation step In addition, at least one cured layer is heat-treated at a temperature between 100 ° C. and 200 ° C. for the polyethylene naphthalate film, or at a temperature between 100 ° C. and 200 ° C. at the same time for the polyethylene naphthalate film. After that, a crosslinkable substance is cured on at least one surface of the polyethylene naphthalate film to form a cured film. The manufacturing method of the transparent conductive film characterized by these.

Hereinafter, embodiments of the present invention will be described.
The transparent conductive film of the present invention is a transparent conductive film formed by forming a conductive film on a substrate containing at least a polyethylene naphthalate film, and the total light transmittance of the substrate is 88% or more, and 150 ° C. The transparent conductive film is characterized in that the shrinkage in the longitudinal direction (MD) and the transverse direction (TD) after heating for 30 minutes is 0.3% or less.

The substrate of the transparent conductive film of the present invention includes at least a polyethylene naphthalate film. For example, the PEN resin used for the PEN film can be synthesized from 2,6-dimethylnaphthalenedicarboxylate and ethylene glycol through an ester exchange reaction and a condensation reaction. Moreover, although a well-known method can be used about the manufacturing method of a PEN film, if the example is shown, PEN resin will be shape | molded into the film of an unstretched state through a melt compressor and T-die, and also if needed. In general, the film is stretched in the MD and TD directions by a biaxial stretching machine. Although an unstretched film can be used as the PEN film used in the present invention, it is desirable to use a stretched film in terms of strength, surface properties, and thickness uniformity. However, if this stretched PEN film is heated as it is at 150 ° C. for 30 minutes, shrinkage of about 0.6% in the MD direction and about 0.4% in the TD direction are recognized.
The substrate used in the present invention requires that the shrinkage after 30 minutes at 150 ° C. be 0.3% or less for both MD and TD. For TP used in harsh environments such as automobiles, it is preferably 0.2% or less. More preferably, it is 0.1% or less. Here, “the shrinkage ratio in the longitudinal direction (MD) and the transverse direction (TD) after heating at 150 ° C. for 30 minutes” means that the substrate is measured at room temperature, heated to 150 ° C. and kept for 30 minutes, and then until room temperature. It is the shrinkage rate measured by returning and measuring again.

  The method for reducing the shrinkage of the substrate is not particularly limited, but it is necessary to reduce the shrinkage of the substrate before the conductive film is attached. After depositing the ITO layer, it is well known to anneal at a temperature around 150 ° C. in order to crystallize the ITO. In this case, the thermal characteristics of the conductive film such as ITO and the organic material such as PEN film are known. Due to the difference, this annealing treatment may leave stress between the ITO layer and the organic interface, and the ITO layer may be peeled off by sliding with a pen or the like, or the layer may be cracked.

  By subjecting the stretched PEN film to a high temperature treatment that keeps the stretched PEN film at a temperature of 100 ° C. to 250 ° C. for several minutes to several hours in advance, the shrinkage after 30 minutes at 150 ° C. can be reduced to 0.3% or less for both MD and TD. . This high temperature treatment may be performed by leaving a roll of a PEN film in a temperature control chamber, or may be performed by continuously supplying the film to a chamber where the temperature is set. The continuous method is preferable from the viewpoint of workability, uniformity, winding tightening, and the like. The temperature and time of the high-temperature treatment are appropriately selected while observing the shrinkage rate of the film, and preferable conditions are conditions where the temperature is maintained at 130 ° C. to 200 ° C. for about 10 minutes to 24 hours. In the low shrinkage treatment of the substrate, as will be described later, at least one of the cured layers is subjected to heat treatment of the PEN film at a temperature between 100 ° C. and 250 ° C., or the PEN film is heated at 100 ° C. to 250 ° C. It is preferable to cure the crosslinkable substance on at least one surface of the PEN film after heat treatment at a temperature between 0 ° C. in order to suppress and stabilize the shrinkage rate of the PEN film.

The PEN film has a glass transition temperature (Tg) as low as about 75 ° C., whereas the PET film is as high as 120 ° C. to 150 ° C., has excellent high-temperature stability, and has sufficient resistance even when used in automobiles. Have.
In addition, the PEN film has a water absorption rate, moisture permeability, and temperature expansion coefficient (40 ° C. to 150 ° C.) of 0.5%, 5.8 g / m ² / day, and 31 to 34 ppm / C, respectively, of the PET film. PEN film is 0.4%, 1.4g / m ² / day, 19-20ppm / C, excellent humidity stability and temperature stability, important for finding transparent conductive film with excellent environmental resistance It is an important point.
From the viewpoint of transparency required for TP, the total light transmittance of the substrate is required to be 88% or more. A normal PEN film has a high total light transmittance of about 82% and a haze value of about 14%, and is not suitable as a base material for TP. In recent years, a PEN film with improved transmittance has been developed, but this also has a transmittance of 86.3% (Teijin's Q65 grade, etc.) and has been conventionally used as a TP substrate. Compared to about 90%, the light transmittance was insufficient for use as TP. This is because the PET film has a refractive index of about 1.65, whereas the PEN film has a refractive index of about 1.75, and the PEN film has a higher light reflectance on the film surface. ing. In order to keep this reflectance small, coating of the surface of the PEN film with a thermosetting resin or a photocurable resin described later is extremely effective and is an important item in the present invention.

  The PEN film may be modified so as not to impair the properties such as transparency and heat resistance. The PEN film may contain additives added for various purposes such as antioxidants, ultraviolet absorbers, colorants, lubricants and the like. Moreover, in order to raise the adhesiveness of the electrically conductive films, such as a sclerosing | hardenable substance and ITO adhering to the surface, an easily bonding process may be made into single side | surface or both surfaces. As the easy adhesion treatment, known methods such as corona discharge, ultraviolet irradiation, plasma treatment, sputter etching treatment, and primer treatment can be used. The coating agent for the easy adhesion layer in the primer treatment is not particularly limited as long as it has the effect. For example, it is known to apply a polyester polymer, an acrylic polymer, or a urethane polymer. ing. It is also possible to include fine particles such as silica as a lubricant in this layer.

  The thickness of the PEN film is not particularly limited, but when used for TP, a film having a thickness of 50 to 400 μm is preferable, particularly a film having a thickness of 75 to 250 μm in view of workability and waist strength. Is preferred. Two PENs can be bonded together to further improve the slidability by utilizing the cushioning property of the adhesive material. In this case, the total thickness of the two PEN films is preferably the above thickness. In this case, another transparent film such as a PET film can be used as one of the film substrates.

The substrate has a cured layer in which a crosslinkable substance is cured and formed on at least one side of the PEN film, so that the substrate can be easily reduced in shrinkage and stable in a severe environment of high temperature and high humidity. It is preferable from the viewpoint. When it has a hardened layer, it may have a single hardened layer, and may have a plurality of hardened layers. Moreover, the hardened layer may be laminated | stacked on the electrically conductive film side of the PEN film, may be laminated | stacked on the opposite side to the electrically conductive film, and may be laminated | stacked on both sides.
The cured layer on which the crosslinkable substance is cured is formed on the surface of the PEN film, stabilizes the PEN film against heat, and adheres ITO to the film at a temperature of about 150 ° C. Since the dimensional change is small even when the paste is cured, the sliding resistance of the transparent conductive film is remarkably improved.

  The crosslinkable substance is not particularly limited, and a known substance can be used. However, a heat crosslinkable substance, a light crosslinkable substance such as an ultraviolet ray crosslinkable substance, a crosslinkable substance by an electron beam, or the like may be used. it can. For example, thermal crosslinkable substances, light crosslinkable substances and electron beam crosslinkable substances include melanin resins, urethane resins, urethane acrylic resins, alkyd resins, acrylic resins, silicon resins, epoxy resins, etc. Mold resins and the like, and two or more of these may be mixed, or a hybrid of two or more of the structures may be used. Initiators and molecular weight regulators are prepared for curing.

  An example of the crosslinkable substance used in the present invention will be given. For example, a crosslinkable monomer having two or more acrylic or methacrylic double bonds in the molecule, a crosslinkable monomer having two or more allyl groups in the molecule, or two or more in the molecule And a crosslinkable monomer having an aromatic vinyl double bond, or an oligomer or polymer thereof.

  Examples of commercially available crosslinkable monomers having two or more acrylic or methacrylic double bonds in the molecule include Biscoat 700 (Osaka Organic Chemical Co., Ltd.), KAYARAD R-551 (Japan) Kayaku Co., Ltd.), Aronix M-315 (Toa Gosei Co., Ltd.), Aronix M-210 (Same), BP-4PA (Kyoeisha Yushi Co., Ltd.), BP-4EA (same), Ubimer UVSA -1002 (manufactured by Mitsubishi Yuka Co., Ltd.), Ubimer UVSA-2006 (same), and the like.

  Examples of the crosslinkable monomer having two or more allyl groups in the molecule include diallyl phthalate, diallyl terephthalate, diallyl isophthalate, triallyl isocyanurate, triallyl cyanurate, and diethylene glycol bisallyl carbonate. Can do.

  Furthermore, as a crosslinkable monomer having two or more aromatic vinyl double bonds in the molecule, for example, divinylbenzene, diisopropenylbenzene, divinyltoluene, trivinylbenzene, diisopropenyltoluene, divinyl Naphthalene, diisopropenylnaphthalene, 4,4′-divinylbiphenyl, 4,4′-diisopropenylbiphenyl and the like can be mentioned.

Furthermore, among the crosslinkable substances, examples of the oligomer include oligomers of the crosslinkable monomer, and the degree of polymerization is usually about 2 to 1,000, preferably about 2 to 100.
Furthermore, among the crosslinkable substances, examples of the polymer include polyether polyurethanes, polyester polyurethanes, polycaprolactone polyurethanes and the like having an ethylenically unsaturated group derived from an acrylic or methacrylic double bond at the molecular end.
Furthermore, what added the silane coupling agent to the epoxy acrylate prepolymer can also be used, and the addition amount of the silane coupling agent is generally 0.5 to 1% by weight, epoxy group, amino group Those having a mercapton group are preferable.
As the urethane-based resin, those obtained by curing a polyol compound having two or more hydroxyl groups in one molecule with a polyfunctional isocyanate compound are suitably used. Examples of the polyol compound include polyether polyols such as ethylene glycol and diethylene glycol, epoxy resin-modified polyols, polyester polyols, saponified ethylene vinyl alcohol copolymers, and phenoxy resins.

In addition, when a crosslinkable substance is used as a heat crosslinkable substance, the other monomer, oligomer, or polymer which has thermopolymerization may be added.
In this case, if the proportion of the heat-crosslinkable substance is reduced, a strong coating film cannot be obtained. Therefore, the proportion is at least 20 wt% or more, preferably 30 wt% or more, more preferably 50 wt% or more. It is necessary.
Moreover, when using as a heat-crosslinkable substance, you may add a radical polymerization initiator.
Examples of the radical polymerization initiator include peroxides and azo compounds, and more specifically, benzoyl peroxide, L-butylperoxybenzoate, azobisisobutyronitrile, and the like. . These radical polymerization initiators can be used alone or in combination of two or more.
The addition amount of the radical polymerization initiator is 0 to 2 parts by weight, preferably 0.001 to 1 part by weight based on 100 parts by weight of the thermally crosslinkable substance.

On the other hand, when the crosslinkable substance is used as a photocrosslinkable substance such as ultraviolet rays, other monomers, oligomers or polymers having photopolymerization may be added. In this case, if the proportion of the photocrosslinkable substance is reduced, a strong coating film cannot be obtained. Therefore, the proportion is at least 20% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more. It is necessary.
Moreover, when using as a photocrosslinkable substance, you may add a photoinitiator.
Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3- Methyl acetophenone, 4-chlorobenzophenone, 4-4′-dimethoxybenzophenone, 4-4′-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy 2-methylpropan-1-one, 2-hydroxy-2-methyl-phenylpropan-1-one, thioxanthone compounds, 2-methyl-1- [4- (methyl Thio) phenyl] -2-morpholinophenyl no-1-one, 2,4,6-trimethylbenzoyl diphenyl - phosphine oxide. These photopolymerization initiators can be used alone or in combination of two or more.
The addition amount of a photoinitiator is 0-5 weight part with respect to 100 weight part of photocrosslinkable substances, Preferably it is 0.1-3 weight part, More preferably, it is 0.2-3 weight part. The photopolymerization initiator can be used in combination with a photosensitizer (polymerization accelerator) such as an amine compound as necessary.

  In addition to the solvent added as necessary, the crosslinkable substance used in the present invention may contain a reactive diluent, an antioxidant, a polymerization inhibitor, a leveling agent, a surfactant and the like.

These curable resins can also be used in combination, and several layers such as laminating a cured layer by light such as ultraviolet rays on a thermally cured layer can be applied. From the viewpoint of transparency and the like, an acrylic resin, a urethane acrylic resin, or a silicon resin is preferably used. A composition obtained by adding various additives such as an antistatic agent and a polymerization initiator is usually diluted with a solution and adjusted so that the solid content of the crosslinkable resin is 20 to 80% by weight.
The thickness of these cured layers is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.3 μm or more, from the viewpoint of thermal stability and sliding resistance. More preferably, it is 5 μm or more, and most preferably 1 μm or more. Further, from the viewpoint of productivity, one layer is preferably 10 μm or less, more preferably 7 μm or less, particularly in the case of a thermosetting cured layer, 7 μm or less from the viewpoint of productivity required for curing. It is particularly preferred that
In addition, the acrylic, urethane, urethane acrylic, and silicon polymers generally have a refractive index of about 1.5, and the refractive index of the PEN film is less than about 1.75. By applying to the surface, the reflectance can be reduced, and the total light transmittance of the PEN film can be increased.

FIG. 1 illustrates a preferred configuration of the transparent conductive film of the present invention. FIG. 1A shows a transparent conductive film having a base 1 and a conductive film 2, wherein the base 1 has a cured layer 4 in which a crosslinkable substance is cured and formed on one side of a PEN film 3. It is an example which has the electrically conductive film 2 on. FIG. 1B is an example in which the substrate 1 has a cured layer 4 in which a crosslinkable substance is cured and formed on one side of the PEN film 3, and the conductive film 2 is formed on the opposite surface of the PEN film 3. . In the present invention, a cured layer is not essential, but in the case of an embodiment having a cured layer in this way, the cured layer may be provided on the conductive film side of the PEN film, or provided on the opposite side of the conductive film. It may be provided on both sides. In any case, as the cured layer, a cured layer in which a thermally crosslinkable substance is cured and formed, a cured layer in which a crosslinkable substance by light is cured and a crosslinkable substance by electron beam is cured and formed. A layer appropriately selected from the cured layers and the like can be used. As a pre-cured layer, the PEN film 3 has a cured layer in which a crosslinkable substance is cured and formed by heat. As described in detail later, the PEN film 3 can be manufactured in a simplified process and has excellent sliding resistance. It is preferable at the point which can obtain property.
1C, D, E, and F are examples in which there are a plurality of hardened layers 4. For example, in FIGS. 1C and 1D, the hardened layer 4a includes a hardened layer on which a thermally crosslinkable substance is hardened. Examples of the cured layer 4b include a configuration having a cured layer in which a light or electron beam crosslinkable substance is cured and formed.

  In a preferred embodiment of the transparent conductive film of the present invention, the substrate includes a cured layer in which a thermally crosslinkable substance is cured and formed, and at least one crosslinkable substance by light or electron beam is cured. A transparent conductive film having a cured layer formed thereon can be mentioned. As the cured layer, it is preferable to use a cured layer in which a crosslinkable material is cured and formed by heat in that the process can be simplified and excellent sliding resistance can be obtained. In applications where scratch prevention is required, it is insufficient in hardness to have the scratch-preventing effect of the transparent conductive film for the TP touch surface with only a thermosetting resin. In general, when used as a TP electrode, it is touched with a finger or a pen or rubbed with a pen, so that the opposite surface (touch surface) of the conductive film such as an ITO layer is not easily damaged. In addition, a high hardness of 3H or more is required. Thermally crosslinkable substances usually have a limit of hardness H or 2H at a thickness of 5 μm or less, and a hardness higher than this is required unless long-term curing is economically disadvantageous or the film thickness is increased. It is difficult to put out. On the other hand, the hardened layer cross-linked by light or electron beam can obtain 3H hardness in a short time.

  Therefore, for example, in the configuration of FIGS. 1C and 1D, as a cured layer mainly for low shrinkage and thermal stabilization, the cured layer 4a is a thermosetting resin layer having a thickness of 5 μm or less, and a scratch preventing layer for obtaining surface hardness is obtained. As a hardened layer that also serves as a role, a hardened layer (in particular, an ultraviolet curable resin layer or an electron beam curable resin layer) in which a hardened layer 4b is cured with a light-curing or electron beam crosslinkable substance having a high curing speed and sufficient hardness. Is preferable in that both productivity and large hardness can be achieved, and thermal stability and sliding resistance are also excellent. From the viewpoint of preventing scratches, it is preferable that the cured layer on which the crosslinkable substance by light or electron beam is cured and formed is provided at least on the side opposite to the conductive film 2 of the PEN film 3 to be a touch surface.

  In the present invention, it is preferable to form the cured layer 4a that is crosslinked by heat on one side of the PEN film 3 first, stabilize against heat, and then form a layer that is crosslinked and cured by light or electron beam. In FIG. 1C, the thermosetting layer 4 a and the light or electron beam curing layer 4 b are formed to overlap on the touch surface, and the conductive film is directly formed on the PEN film 3. In FIG. 1D, the thermosetting layer 4a and the light or electron beam curing layer 4b are formed on both sides of the PEN 3, and the conductive film 2 is formed on the thermosetting layer 4a. FIG. 1D shows that a hardened layer is formed at least on both sides, and that it is difficult to warp when used as an electrode. This is a preferable configuration in that it is difficult for the above to occur. Further, the hardened layer of 4a or 4b can be a hardened layer having an antiglare effect in order to enhance the visibility of the TP used outside.

  The hardened layer that is crosslinked by heat is not used for the conventional resin layer provided on the touch surface opposite to the ITO surface for the purpose of preventing scratches because the hardness is slightly insufficient as described above. Currently used TP electrodes often have a cured layer that is cross-linked by light on the TP touch surface.

It is also preferable to further provide a hardened layer from the viewpoint of further improving the sliding resistance. For example, in FIGS. 1E and 1F, the cured layer 4a has a cured layer on which a thermally crosslinkable substance is cured, and the cured layers 4b and 4c are cured with a light or electron beam crosslinkable substance. And the like having a cured layer formed. 4b and 4c layers are present on both sides of the PEN film, the touch surface has a hardness of 3H or higher, can provide anti-Newton ring performance, and has a hardened layer on both sides to achieve a mechanical strength balance. It is the most preferable configuration because it is difficult to warp, and by making the both surfaces 3H or more, it is difficult to generate scratches or the like in the process or handling. In FIG. 1E and FIG. 1F, first, a cured layer 4a that is crosslinked by heat is applied to the PEN film 3, and dried and cured at 100 ° C. to 250 ° C. After this, a hardened layer that can be cross-linked by light or electron beam can be formed either on the 4a layer or on the non-coated surface of the 4a layer, and then the hardened layer can be similarly formed on the opposite surface. . In this case, it is desirable to select the type, thickness, and degree of crosslinking of the resin so that the touch surface of TP is 3H or more. The hardness of the surface to which the conductive film such as ITO is applied is not necessarily 3H, but it is possible to suppress the generation of scratches in the process and handling, and considering the balance of mechanical strength on both sides, the type of resin , Thickness, degree of crosslinking, etc. can be selected.
In addition, when providing a hardened layer on both sides, selecting one with the same degree of thermal expansion coefficient on both sides can balance the strength and cause wrinkles or cracks when exposed to high heat. It is preferable in terms of difficulty. 1E and 1F are the most preferable configurations from the viewpoint of practical use for TP.
When laminating a cured layer on which a thermally crosslinkable substance is cured and a cured layer on which a crosslinkable substance by light or electron beam is cured, the overall thickness of the overcoated layer depends on the required hardness. However, if it is about 3H which is generally required, 2 μm to 10 μm is preferable. Judging comprehensively from productivity, low shrinkage, its stability, hardness, etc., the thermosetting resin layer is 0.5 μm to 5 μm, and the ultraviolet curable layer applied on this is 1 to 6 μm. Is preferred.

In addition, the cured layer (at least one of the cured layers in the case where there are a plurality of cured layers) is used for the processing necessary for the transparent conductive film for TP, such as image glare prevention, reflection prevention, and Newton ring generation prevention. ) Various additives or treatments can be added. For these purposes, the substrate may be further coated with heat or ultraviolet curable resin.
The anti-Newton ring effect can be imparted to the hardened layer below the surface on which the conductive film is formed, for example, the 4c layer in FIG. 1E and the 4b layer in FIG. 1F. Specifically, organic particles such as acrylic particles and inorganic particles such as silica particles are included in the resin component that is cross-linked by light or electron beam so that the haze value is 0.5 to 3%. Can be cured. When blended so that the haze value is small, the anti-Newton ring effect is small, and when it is large, glare may occur in the image. The haze value of this layer is between 0.5% and 3%, It is preferable to adjust. These particles are preferably mixed with particles having different diameters than those having a uniform particle diameter from the viewpoint of achieving a balance between anti-Newton ring property and prevention of image glare. Specifically, a mixture of particles having different diameters in the range of 1 to 6 μm is preferable, and a mixture of particles having different diameters in the range of 2 to 5 μm is more preferable.

  Anti-glare is preferred for displays used externally such as TP used in automobiles. Also in the case of providing the antiglare effect, for example, the layers 4a, 4b, and 4c in FIGS. E and F can be selected by controlling the haze value and selecting the total haze value. Generally, the haze value is selected between 2% and 20%. The haze value can be obtained by curing a resin component that is cross-linked with acrylic particles or silica particles mixed therein. In order to obtain a target haze value, it is preferable to adjust 4b and 4c obtained by curing a resin that crosslinks with light or an electron beam as the same haze value from the viewpoint of reducing the number of types of resin for obtaining a cured layer. Further, an embodiment in which at least one of the cured layers is a layer having an antiglare function having a haze value of 1 to 20% is preferable.

Further, it is preferable that the cured layer on the opposite side of the PEN film to the conductive film also has an antiglare and Newton ring preventing effect by including silica particles or the like.
In the case of a clear coat, it is preferable that none of the hardened layers contain particles such as silica or acrylic, and the overall haze value is preferably suppressed to 2% or less. Also in this case, generation of Newton rings may be avoided, silica particles and acrylic particles can be included in the cured layer below the ITO layer, and it is preferable to adjust the haze value to 2% or less.
Silica particles are amorphous and porous, and a typical example is silica gel. A typical example of organic particles is acrylic particles. The average particle diameter is usually 30 μm or less, preferably about 2 to 15 μm, and the blending ratio is such that the particles are 0.1 to 10 parts by weight with respect to 100 parts by weight of the curable resin. Is preferred. Further, when the layer in contact with the conductive film of the substrate is an antiglare layer or an anti-Newton ring layer containing particles, the sliding resistance can be further improved. In other words, when a hardened layer containing particles such as silica is attached to give an effect of preventing Newton's ring, a conductive substance is formed on top of this, and the hardened layer containing particles becomes conductive. Since it is possible to improve the sliding resistance when it is at the lower part of the film, it is a preferable configuration.

  About the aspect which is a transparent conductive film of this invention and has a hardened layer, although the PEN film by which the low shrinkage process was carried out by the above methods was prepared previously, a hardened layer may be laminated | stacked on this PEN film. In this method, a long process is required, and a great deal of labor is required in the process, which causes a cost problem. Using raw material of biaxially stretched film that has a low shrinkage of about 0.5% at 150 ° C for 30 minutes as a material, the process of laminating the low shrinkage and the thermosetting layer in-line is performed simultaneously or continuously. It is preferable from the viewpoint of improving the sliding resistance when a conductive film is obtained because the cost and stability of the film can be stabilized.

In a preferred embodiment of the present invention, the cured layer crosslinkable material is cured film formation, the roll of PEN film, is continuously fed while applying a stress of 2 kg / cm ² to 50 kg / cm ² PEN A crosslinkable substance is applied to the film by a method such as a die coater, reverse coater, gravure coater, micro gravure coater, spray coater, slot orifice coater, roll coater, or screen printing. In the case of a substance, the temperature of the furnace can be set from the viewpoint of the degree of cross-linking, the thermal stability of the film, and the time kept in the furnace. Generally, it can be produced by a method of passing through a furnace set at 100 ° C. to 250 ° C., curing and winding. At this time, curing of the crosslinkable substance and heat treatment of the PEN film are simultaneously performed at a temperature of 100 ° C. to 250 ° C. Usually, it is preferable in terms of productivity that the furnace is cured for 1 to 60 minutes. The furnace may be a single chamber, but by dividing the chamber into several chambers and adjusting the temperature, the generation of bubbles can be suppressed, the curing speed can be adjusted, and the smoothness of the cured film can be increased. This method is preferable in that it is not necessary to heat-treat the PEN film in advance to reduce the shrinkage, and the process can be simplified. In addition, the substrate on which the heat treatment of the PEN film and the cured layer are simultaneously cured has good sliding resistance.

  When the crosslinkable material to be applied is to first cure a photocrosslinkable material (for example, UV crosslinkable) or an electron beam crosslinkable material instead of a heat crosslinkable material to increase the thermal stability of the PEN film. Apply the crosslinkable substance before passing through the furnace as in the case of the heat crosslinkable substance, pass through the furnace set at 100 ° C. to 250 ° C., and then cure by applying ultraviolet rays or the like, After passing through a furnace set at 100 ° C. to 250 ° C., it is cooled and coated with a crosslinkable substance, dried through a furnace set at about 20 ° C. to 130 ° C., and then cured by applying ultraviolet light or the like. . For the purpose other than stabilization of the PEN film, for example, to increase the hardness to 3H, a known method can be used for coating and curing a substance that crosslinks with light or an electron beam. For example, an ultraviolet curable resin can be applied to a PEN film with a gravure coater, dried and then irradiated with ultraviolet rays to be cured.

The conditions for curing the photocrosslinkable substance can be appropriately selected from the viewpoints of the substance used, the curing speed, the curing condition, and the like. For example, irradiation with ultraviolet rays having a wavelength in the range of 200 to 500 nm is performed for 0.1 seconds or longer, preferably 0.5 to 60 seconds.
Here, the integrated amount of irradiation is usually from 30 to 5.000 mj / cm ² , and as a light source, a low pressure mercury lamp, a high pressure mercury lamp, a carbon arc, a metal halide lamp, a mercury discharge tube, a tungsten lamp, A halogen lamp, a sodium discharge tube, a neon discharge tube, or the like can be used.

  The shrinkage rate can be controlled by the tension of the PEN film, the furnace temperature, the curing rate, and the like when the curable resin is applied.

A transparent conductive film having a low shrinkage PEN film as a base material can be obtained by attaching a conductive substance to the thus obtained base having a low shrinkage rate to form a conductive film. In the case of a configuration having a cured layer on one side of the PEN film, the conductive substance may be attached to either the surface on the side where the cured layer is provided or the surface on the side where the cured layer is not provided. Good. As the transparent conductive material, a known material such as ITO, ZnO, SnO ₂ , Cu, or Ag is used, and ITO is preferably used from the viewpoint of a balance between transparency and conductivity. As a method for adhering to the PEN film, known methods such as sputtering, CVD, ion plating, and coating can be applied, but sputtering is performed from the viewpoint of adhesion of conductive materials, ease of control of conductivity, low resistance, and the like. The method of attaching by the method is preferred. The transparent conductive material may be attached using a batch-type apparatus or a roll-to-roll continuous method, but a continuous method is preferable from the viewpoint of ease of control and productivity. ITO is sputtered in an atmosphere of argon gas and oxygen gas using an ITO (indium tin oxide) target or an indium-tin alloy target.

The temperature at which sputtering is performed is not particularly limited as long as a resistance value suitable for TP can be imparted, but can be performed at room temperature to 200 ° C. When the conductive film is ITO, the temperature is preferably 60 ° C. or higher, more preferably 100 ° C. or higher, in order to sufficiently oxidize the ITO film and improve the adhesion of the ITO film. When the temperature is 200 ° C. or higher, the oligomer remaining in the PEN film may be precipitated and become cloudy, and the PEN film may be deformed, which is not preferable. Sputtering at as high a temperature as possible, for example, 100 ° C. to 280 ° C. within the range where the above-mentioned problems do not occur during sputtering is preferable because the adhesion of ITO to the substrate is excellent and partial crystallization of ITO proceeds. The PEN film of the present invention can thus enable sputtering at high temperatures.
The thickness of the conductive thin film is not particularly limited as long as conductivity can be imparted, but it is preferably 50 mm or more, and if it is too thin, the surface resistance value becomes high, and when used as a TP electrode, It becomes 1000Ω / □ or more, and it is difficult to form a continuous thin film having good conductivity. On the other hand, if the thickness is too large, the transparency is lowered, sputtering time is required, an expensive conductive film material is required, and this is not preferable from the viewpoint of cost. From such a viewpoint, the preferred thickness is 100 to 2000 mm.

Normally, ITO deposited after sputtering is amorphous, but it can also be crystallized at a temperature around 150 ° C. Here, the manufacturing method of crystallized ITO is demonstrated in detail. As a method for forming ITO on the polymer film, a known method such as a DC magnetron sputtering method, an RF magnetron sputtering method, an ion plating method, or a vacuum deposition method can be used. From the viewpoint of film uniformity, the DC magnetron sputtering method is preferred. As a target for sputtering, a mixed sintered target of In ₂ O ₃ and SnO ₂ can be used. Alternatively, reactive sputtering may be performed using a metal target of In and Sn. From the viewpoint of productivity, it is preferable to use a mixed sintered target.

The concentration of SnO ₂ in the In—Sn—O material is not particularly limited, but is preferably 2 to 20 wt%, and In—Sn— having 4 to 13 wt% SnO ₂ from the viewpoint of reducing the resistance value. O-based materials are preferred.
It is possible to deposit ITO on the polymer film by sputtering using the In—Sn—O target thus selected. ITO formed by sputtering is generally amorphous. The method for crystallizing this is not particularly limited, and a known method can be used as appropriate. It is considered that the influence on the generation of crystal nuclei in the ITO film is largely due to the atmosphere during sputtering and the partial pressure of oxygen to be added. In general, when the oxygen partial pressure to be added is increased, indium oxide is stoichiometrically close to In ₂ O ₃ , and thus tends to be a crystal nucleus. In order to avoid the influence of residual gas as much as possible in the film forming atmosphere, the degree of vacuum is preferably 10 ⁻⁶ Torr or less. It is preferable to introduce oxygen together with an inert gas such as argon gas after controlling the residual gas in the vacuum chamber, and the partial pressure of oxygen is preferably 1 to 10 × 10 ⁻⁵ Torr. Nitrogen, water, etc. may be added.

The conversion to crystalline ITO is usually carried out by keeping it in a bath set at a temperature between 100 ° C. and 250 ° C. for several minutes or more. In the PEN film of this invention, it is preferable to carry out in the range of 100 to 200 degreeC from a deformability, efficiency, etc. Especially preferably, it is 120 to 170 degreeC. It can be carried out while continuously feeding the film or batchwise. The atmosphere during the overheat treatment is preferably air, but there is no problem even if nitrogen or the like is mixed. The crystal particle diameter is preferably 0.5 μm or less because disconnection is likely to occur if the crystal particle diameter is large from the viewpoint of bending resistance.
In the present invention, amorphous ITO or crystalline ITO may be used, but TP used in automobiles is required to have a small change in resistance value even under severe conditions of temperature 85 ° C. and humidity 85%. From the viewpoint, crystallized ITO is preferably used.
The plastic film used in the present invention has a thermal shrinkage rate of 0.3% or less, and the shrinkage rate of the film is small because the shrinkage rate of the film is small at the time of high-temperature treatment required for crystallization of ITO. It is difficult for the ITO layer to peel or crack from the ITO film due to the difference from the non-shrinkage of the ITO, and even when these peelings and cracks do not occur, large stress remains at the interface between the ITO and the film. However, a large change in resistance value may occur due to mechanical stimulation when used as a TP or dimensional change of the film in a harsh environment, but it also works beneficially in that these changes can be kept small. .

  When a high refractive material is attached under this conductive film or on the opposite surface of the PEN film and a low refractive material is attached thereon, a transparent conductive film with low reflection can be obtained. The high refractive material can be deposited by attaching titanium oxide or zirconium oxide by a technique such as vapor deposition or sputtering, or by containing these particles in a material that is cured by ultraviolet rays or heat. The low refractive material can be deposited by depositing SiOx (x = 1 to 2) or the like, which is a dielectric shown below, by vapor deposition or sputtering, or by curing a fluorine-based resin with heat or ultraviolet rays. This layer for low reflection may be applied to either side of the PEN film, or may be applied to both sides for further low reflection. In recent years, the demand for TP having a high transmittance has increased, and an antireflection layer can be preferably used.

It may be preferable to form a transparent dielectric thin film on the conductive thin film because the transparency and scratch resistance may be further improved. The dielectric thin film is preferably smaller than the refractive index of the conductive thin film, usually having a refractive index of 1.3 to 1.8. For example, CaF ₂ , MgF ₂ , Al ₂ O _3, SiOx (x = 1-2) and the like are used, and among these, SiOx is inexpensive and preferable. These materials can be used in combination of two or more. The film thickness of the dielectric is not particularly limited, but is usually 100 to 3000 mm, preferably 200 to 1500 mm. When it is thin, it is difficult to obtain a continuous thin film. When it is too thick, conductivity and transparency are deteriorated and cracks are likely to occur.

  Further, when the transparent conductive film is used in a display device or the like, fingerprints or dirt may be generated on the surface thereof during processing or use. In order to solve this problem, a water repellent or antifouling layer can be attached to the outermost layer surface opposite to the surface on which the conductive film is formed. Examples of the material having such an effect include a fluorine-containing resin such as a silicon-containing compound, polytetrafluoroethylene, polychlorotrifluoroethylene, or the like, which is a combination of a dimethylpolysiloxane containing a hydroxyl group or a vinyl group and a methylhydropolysiloxane. In addition, molybdenum sulfide or the like may be used alone or in combination, and known substances such as alkyd resins may be used. These formation methods are not particularly limited, and a coating method, a spray method, a vacuum deposition method, a sputtering method, a baking method, or the like can be used depending on the material to be used. The thickness of the treatment layer is not particularly limited, but is usually about 100 to 50 μm. This treatment can be carried out in combination of two or more, and is efficient when used in combination with a curable resin.

The transparent conductive film of the present invention has good sliding resistance in the above configuration, but the above-mentioned base is the first base, and an adhesive layer is provided on the surface of the first base opposite to the conductive film. A second substrate may further be provided. Here, not only the first substrate but also the second substrate can be further improved in sliding resistance by setting the thermal shrinkage rate to 0.5% or less by the method already described. Only the first substrate may have a low shrinkage, but it is preferable that both the substrates have a low shrinkage using the method of the present invention because the effect of sliding resistance is increased.
As a configuration having such a second substrate, for example, a transparent substrate may be bonded to the other surface of the low-shrinkable substrate on which the conductive thin film is formed via a transparent adhesive layer. For this bonding, a pressure-sensitive adhesive layer may be provided on a transparent substrate, and a low-shrinkage substrate on which the conductive thin film is formed may be bonded to the transparent substrate. A pressure-sensitive adhesive layer may be provided on the shrinkable substrate, and a transparent substrate may be bonded thereto. From the viewpoint that the pressure-sensitive adhesive layer can be continuously formed with the film base as a roll, it is advantageous in terms of productivity to provide the pressure-sensitive adhesive layer on the low-shrinkage substrate.

In addition, for example, a second transparent substrate is bonded to the first substrate with low shrinkage via a transparent adhesive layer, and the total thickness is 40 to 300 μm. A conductive thin film may be provided.
The pressure-sensitive adhesive layer can be used without particular limitation as long as it has transparency, and examples thereof include an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a rubber-based pressure-sensitive adhesive. From the viewpoint of improving the scratch resistance and hit point characteristics of the transparent conductive film, the elastic modulus is in the range of 1 × 10 ⁵ to 1 × 10 ⁷ dyn / cm ² , and the thickness is in the range of 1 μm or more, usually in the range of ⁵ to 100 μm. It is desirable to set. When the above elastic modulus is less than 1 × 10 ⁵ dyn / cm ² , the pressure-sensitive adhesive layer becomes inelastic. Therefore, it is easily deformed by pressurization, causing irregularities in the substrate and the conductive thin film, and the processed cut surface. The pressure-sensitive adhesive sticks out easily from the surface, and the effect of improving the scratch resistance and the spot characteristics is reduced. On the other hand, if the elastic modulus exceeds 1 × 10 ⁷ dyn / cm ² , the pressure-sensitive adhesive layer becomes hard and the cushioning effect cannot be expected, so the scratch resistance and the hitting point characteristics cannot be improved, and the effect of bonding cannot be expected. . Further, when the thickness of the pressure-sensitive adhesive layer is less than 1 μm, the cushioning effect cannot be expected, so that the scratch resistance and the hit point characteristics cannot be improved, and the effect of bonding cannot be expected. If it is too thick, the transparency is impaired, and it is difficult to obtain good results in terms of forming an adhesive layer, bonding workability of a transparent substrate, and cost.

  When the second transparent substrate bonded through the pressure-sensitive adhesive layer in the configuration having the second substrate is required to be flexible even after bonding, the plastic film is When flexibility is not particularly required, a glass plate or a film-like or plate-like plastic is used. When the transparent substrate is a plastic film, the aforementioned low-shrinkage PEN film or another plastic film may be used. Specific examples of the film material include polyimide, polyethersulfone, polyetheretherketone, polycarbonate, polypropylene, polyamide, polyacryl, acetylcellulose, polyarylate, polysulfone, and norbornene-based polymers. The norbornene-based polymer includes a polymer obtained by ring-opening polymerization or addition polymerization of a monomer having a norbornene structure and another polymerizable monomer added as necessary. Trade names ZEONEX and ZEONOR, which are non-polar norbornene polymers, trade names Arton, which is a polar norbornene polymer from JSR Corporation, and trade names, Appell, and Hoechst, developed by Mitsui Chemicals, Inc. Examples thereof include, but are not limited to those listed here, and polymers containing norbornene-based structures are included.

  In the configuration having the second substrate, the thickness of the second transparent substrate bonded via the pressure-sensitive adhesive layer is preferably in the range of 2 to 300 μm. If it is thinner than 2 μm, the mechanical strength is not obtained and the significance of making a laminated structure is scarce, and it is difficult to apply a pressure-sensitive adhesive layer in the form of a roll or to perform a continuous operation such as a hard coating process described later. In addition to this, wrinkles or the like may occur in pasting. From such a viewpoint, the thickness is preferably 10 μm or more, and particularly preferably 20 μm or more. When the thickness is 300 μm or more, the roll shape causes a curl, and not only continuous work is difficult, but also the curl remains and cannot be used. From such a viewpoint, the preferable thickness is 250 μm or less, and particularly preferably 230 μm or less.

  As described above, the present invention is applicable to the case where the substrate including the PEN film is used as a TP electrode by setting the thermal shrinkage ratio after heating at 150 ° C. for 30 minutes to 0.3% or less for both MD and TD. Thus, there was no warpage even when exposed to high temperatures in the production process, and a transparent conductive film with little deviation in electrode position and extremely improved sliding resistance could be obtained. In particular, a transparent conductive film obtained by adhering a conductive film to a substrate obtained by curing a crosslinkable resin to a PEN film while being heat-treated at 100 to 250 ° C. was extremely excellent in the sliding resistance.

  The method for producing a transparent conductive film of the present invention is a substrate having at least a PEN film and a cured layer on which a crosslinkable substance is cured and formed, and the longitudinal direction (MD) after heating at 150 ° C. for 30 minutes And a substrate preparation step for preparing a substrate having a shrinkage rate in the transverse direction (TD) of 0.3% or less, and a conductive film attachment step for attaching a conductive film to the substrate prepared by the substrate preparation step. In the substrate preparation step, at least one cured layer is heat-treated at a temperature between 100 ° C. and 250 ° C. at the same time as the PEN film, or at a temperature between 100 ° C. and 250 ° C. Then, a crosslinkable substance is cured on at least one surface of the PEN film to form a cured film. According to the manufacturing method of the present invention, there is no warpage even when exposed to high temperatures in the manufacturing process, the electrode position is small, transparency, environmental resistance (high temperature, high humidity and high temperature durability), and sliding resistance A transparent conductive film having extremely improved properties can be obtained.

  The most effective method is a method in which a heat-crosslinking type resin is first applied to a PEN film, and is then dried and cured at a temperature of 100 ° C. to 250 ° C. for several minutes to several hours. According to this method, the dimensional stability and thermal stability of the PEN film can be performed simultaneously in one step, and the transparent conductive film having excellent transparency, environmental resistance and sliding resistance. Can be manufactured. Although the process is two steps, the PEN film can be heat-treated in advance at 100 ° C. to 250 ° C., and a resin that is crosslinked with heat, light, or electron beam can be applied and cured. The PEN film obtained by curing the crosslinkable material thus obtained is further laminated with a crosslinkable cured layer according to the purpose. A conductive layer such as ITO is attached to the PEN film on which the cured layer is laminated. In the present invention, before the conductive layer such as inorganic ITO is attached, it is necessary that the PEN film has a reduced shrinkage with respect to heat and is stabilized.

In the substrate preparation step, at least one cured layer is crosslinked after the PEN film is heat-treated at a temperature between 100 ° C. and 250 ° C. and before the PEN film is cooled to room temperature. According to the method of curing the above substance on at least one surface of the PEN film and forming a cured film, a transparent conductive film having good sliding resistance can be easily produced.
In particular, using a biaxially stretched PEN film that has not been subjected to low shrinkage treatment, a cured layer that has been crosslinked and cured by heat is subjected to heat treatment at a temperature between 100 ° C. and 250 ° C. and at least one of the PEN films. A transparent conductive film that can be made of an inexpensive material, can be used inexpensively, eliminates the need for a heat treatment of the PEN film in advance, and has excellent sliding resistance. Can do.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
A thermosetting acrylic with a gravure coater while continuously feeding on one side of a 188μm thick highly transparent biaxially stretched PEN film (SK20 TK20) on a roll at a tension of 10kg / cm ² A solution obtained by dissolving 100 parts by weight of a resin (U-230 manufactured by Soken Chemical Co., Ltd.) and 30 parts by weight of a curing agent (Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.) in 100 parts by weight of toluene so that the coating thickness after drying is 3 μm. Applied. This was cured at the same time as drying while being continuously fed at a rate of 2 m / min to a drying furnace consisting of 4 chambers each having a length of 5 m set at 120 ° C., 145 ° C., 155 ° C. and 130 ° C. . Let the obtained film be A1. When the shrinkage of the A1 film after 1 hour at 150 ° C. was measured, it was 0.16% in the MD direction and 0.05% in the TD direction, and the pencil hardness of the coated layer was 2H. An indium-tin alloy (tin) in a 0.30 Pa atmosphere composed of 80% argon gas and 20% oxygen by a direct current sputtering apparatus while continuously supplying in roll form on the surface opposite to the coated surface of the A1 film. A transparent conductive thin film made of a composite oxide (ITO) of indium oxide and tin oxide having a thickness of 28 nm is attached by reactive sputtering using a target made of 6 wt%) to obtain a transparent conductive film B1. It was. The total light transmittance of this B1 film was 87.9%, and the surface resistance value was 400Ω / □. Table 1 shows the characteristics when this film B1 was used as an electrode for TP.

(Example 2)
The highly transparent biaxially stretched PEN film used in Example 1 was left in a constant temperature bath set at 150 ° C. for 24 hours, and heat treatment was performed in advance. A solution obtained by adding Aurex 344 (100 parts by weight) made of Chinese paint and Irgacure 184 (5 parts by weight) to 100 parts by weight of toluene was continuously applied to one surface with a die coater so as to have a thickness of 4 μm. Then, it consists of the same four chambers as in Example 1 and is supplied to a drying furnace set at 70 ° C., 100 ° C., 110 ° C., and 90 ° C. at 20 m / min, dried, and then turned into a 120 W / cm high-pressure mercury lamp. The film A2 coated with a UV curable resin was obtained by irradiating it with ultraviolet rays. When the thermal contraction rate of this A2 film was measured in the same manner as in Example 1, it was 0.18% in the MD direction and 0.06% in the TD direction, and the pencil hardness of the coated surface was 3H. ITO was attached to the surface opposite to the coated surface of the A2 film in the same manner as in Example 1 to obtain a transparent conductive film B2. The total light transmittance of this film B2 film was 88.0%, and the surface resistance value was 410Ω / □. Table 1 shows the characteristics when used as the TP electrode of the B2 film.

(Example 3)
In the same manner as in Example 2, a UV curable resin was further applied to the application surface of the A1 film on which the thermosetting resin obtained in Example 1 was applied. Further, a solution (AG coating solution) obtained by adding 7 parts by weight of silica particles having an average particle size of 4 μm to the UV curable coating solution of Example 2 and mixing it uniformly on the surface opposite to the coated surface of this film. In the same manner as in Example 2, coating, drying and curing were performed to obtain a UV cured layer of antiglare (AG) having a thickness of 3 μm, and a film A3 coated on both sides was obtained. The A3 film was measured for heat shrinkage and pencil hardness in the same manner as in Example 1. As a result, it was 0.12% in the MD direction, 0.03% in the TD direction, and the pencil hardness was 3H on both sides. ITO was adhered to the AG surface of this A3 film in the same manner as in Example 1 to obtain a film B3. The haze value of this film was 2%, the total light transmittance was 88.5%, and the surface resistance value was 420Ω / □. Table 1 shows the characteristics of the B3 film as the TP electrode.

Example 4
The film B3 obtained in Example 3 was subjected to a heat treatment for 24 hours with a hot air dryer maintained at 150 ° C. to crystallize most of the ITO to obtain a film B4. The haze value of B4 was 2.2%, the total light transmittance was 86.8%, and the surface resistance value was 320Ω / □. Table 1 shows the characteristic values of the film B4 as a TP electrode.

(Example 5)
The AG coating solution of Example 3 was applied, dried and cured in the same manner as in Example 3 on the coated surface of the A1 film obtained in Example 1 to obtain a coating layer having a thickness of 4 μm. Further, an AG coating layer having a thickness of 3 μm was obtained on the opposite surface in the same manner as in Example 3, and a film A4 having a double-sided AG coating layer was obtained. When the thermal shrinkage and pencil hardness of this A4 film were measured in the same manner as in Example 1, it was 0.11% in the MD direction, 0.03% in the TD direction, and the pencil hardness was 3H on both sides. In the same manner as in Example 1, ITO was attached to the surface of only one AG coat layer of this A4 film to obtain a film B5. The haze value of the B5 film was 9.0%, the total light transmittance was 88.3%, and the surface resistance value was 410Ω / □. Table 1 shows the characteristics of the B5 film as a TP electrode.

(Example 6)
The film B5 obtained in Example 5 was heat-treated in the same manner as in Example 4 to crystallize most of ITO to obtain a film B6. The haze value of B6 was 9.5%, the total light transmittance was 86.5%, and the surface resistance value was 315Ω / □. Table 1 shows the characteristic values of the film B6 as a TP electrode.

(Comparative Example 1)
A film A5 was obtained in the same manner as the film A2 of Example 2 except that the highly transparent biaxially stretched PEN film was not subjected to heat treatment for 24 hours in a thermostat set at 150 ° C. When the thermal shrinkage and hardness of this A5 film were measured in the same manner as in Example 1, it was 0.52% in the MD direction, 0.22% in the TD direction, and the pencil hardness of the UV cured layer was 3H. ITO was adhered to the A5 film in the same manner as in Example 1 to obtain a film B7. The total light transmittance of B7 was 87.7%, and the surface resistance value was 435Ω / □. Table 1 shows the characteristics of the B7 film as a TP electrode.

(Comparative Example 2)
In Example 3, except that the thermosetting resin coating was omitted, UV coating with a thickness of 3 μm was performed on both sides in the same manner as in Example 3 to obtain a film A6. When the thermal shrinkage of this film A5 was measured in the same manner as in Example 3, it was 0.5% in the MD direction and 0.2% in the TD direction, and the pencil hardness was 3H on both sides. ITO was adhered to the surface on which the AG coat layer was applied in the same manner as in Example 1 to obtain a film B8. The haze value of the film B8 was 2.1%, the total light transmittance was 88.4%, and the surface resistance value was 420Ω / □. The characteristics of the film B8 as a TP electrode are shown in Table 1.

(Comparative Example 3)
Film B8 obtained in Comparative Example 2 was heat-treated in exactly the same manner as in Example 4 to crystallize most of ITO to obtain Film B9. This film B9 had a haze value of 2.4%, a total light transmittance of 86.3%, and a surface resistance value of 315Ω / □. The characteristics of this film B9 as a TP electrode are shown in Table 1.

(Comparative Example 4)
A film A7 was obtained in exactly the same manner as the film A5 of Comparative Example 1 except that a 188 µ PET film (A4300 manufactured by Toyobo Co., Ltd.) was used instead of the PEN film. When the thermal contraction rate and surface hardness of the film A7 were measured in the same manner as in Comparative Example 1, it was 1.0% in the MD direction, 0.5% in the TD direction, and the surface hardness of the coat layer was 3H. To this, ITO was adhered in the same manner as in Comparative Example 1 to obtain a film B10. Film B10 had a total light transmittance of 88.2% and a surface resistance value of 415Ω / □. The characteristics of the film B10 as a TP electrode are shown in Table 1.

In addition, the 10 cm square film B was left to stand for 60 minutes in the electric furnace set to 150 degreeC, and the lift of the edge part was measured.
For linear sliding, a TP module is made through glass ITO and a spacer, reciprocated 150,000 times with a 0.8R polyacetal pen under a load of 500 g, the resistance value of that part is measured, and the resistance from the initial value The percentage change in value was calculated.
The resistance value change after 85 hours at 85 ° C. is measured for 240 hours after placing a 210 mm square film B in a high-temperature and high-humidity tank maintained at a temperature of 85 ° C. and a humidity of 85% and then cooling to room temperature. The rate of change from the initial value was calculated.
The total light transmittance and haze value were measured with a turbidimeter (NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS-K7105.

  As shown in the above examples, the transparent conductive film of the present invention has a small warp after heat treatment at 150 ° C. for 1 hour, and has been subjected to a linear and character sliding test when used as an electrode of TP. However, it can be seen that the resistance value change is small, and the TP electrode has extremely excellent environmental resistance and durability.

  The transparent conductive film of the present invention can be used as a transparent electrode for displays such as TP.

FIG. 1A is a diagram showing an example of the transparent conductive film of the present invention. FIG. 1B is a diagram showing another example of the transparent conductive film of the present invention. FIG. 1C is a diagram showing another example of the transparent conductive film of the present invention. FIG. 1D is a diagram showing another example of the transparent conductive film of the present invention. FIG. 1E is a diagram showing another example of the transparent conductive film of the present invention. FIG. 1F is a diagram showing another example of the transparent conductive film of the present invention.

Claims (7)

A transparent conductive film formed by forming a conductive film on a substrate containing at least a polyethylene naphthalate film, wherein the substrate has a total light transmittance of 88% or more, and after heating the substrate at 150 ° C. for 30 minutes A transparent conductive film, wherein the shrinkage in the longitudinal direction (MD) and the transverse direction (TD) is 0.3% or less. The transparent conductive film according to claim 1, wherein the substrate has a cured layer on at least one side of the polyethylene naphthalate film. The transparent conductive film according to claim 1, wherein the substrate has a cured layer in which a thermally crosslinkable substance is cured and formed as a cured layer. The transparent conductive film according to claim 2 or 3, wherein the substrate has a cured layer in which a crosslinkable substance by light or electron beam is cured. The transparent conductive film according to claim 4, wherein the base has a cured layer on which a crosslinkable substance by light or electron beam is cured and formed on both sides of the polyethylene naphthalate film. The transparent conductive film according to claim 1, wherein the conductive film is indium tin oxide. A substrate having at least a polyethylene naphthalate film and a cured layer on which a crosslinkable substance is cured, and shrinkage in the longitudinal direction (MD) and the transverse direction (TD) after heating at 150 ° C. for 30 minutes Each of which has a substrate preparation step of preparing a substrate of 0.3% or less, and a conductive film attachment step of attaching a conductive film to the substrate prepared by the substrate preparation step. One layer of the cured layer is subjected to heat treatment of the polyethylene naphthalate film at a temperature between 100 ° C. and 200 ° C. or after heat treatment of the polyethylene naphthalate film at a temperature between 100 ° C. and 200 ° C. A crosslinkable substance is cured on at least one surface of the polyethylene naphthalate film and formed by curing film formation. The method for producing a transparent conductive film to be.

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