JP2006206831A - Transparent conductive film and touch panel using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive film which has excellent transparency and excellent interference fringe (iris-like color)-inhibiting property, and is not curled, even when thermally treated in a process for producing a touch panel, and to provide a touch panel using the film. <P>SOLUTION: This transparent conductive film comprising a substrate film having a coating layer, a hard coat layer laminated to the coating layer of the substrate film, and a transparent conductive thin film laminated to the other side of the substrate film is characterized in that the substrate film is a coating layer-having biaxially oriented polyester film prepared by coating a polyester film with a water-based coating liquid containing an aqueous polyester resin (A) and at least one compound (B) selected from water-soluble titanium chelate compounds, water-soluble titanium acylate compounds, water-soluble zirconium chelate compounds and water-soluble zirconium acylate compounds as main constituents in a (A)/(B) mass ratio of 10/90 to 95/5, drying the coated film, and then orienting the dried film in at least one direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transparent conductive film obtained by laminating a transparent conductive thin film on the other side of a coating layer surface of a biaxially stretched polyester film on which an interference fringe improving coating layer is laminated, and a touch panel using the same. It is. In particular, a transparent conductive film that is excellent in transparency when used in a touch panel, suppresses interference fringes (iris-like colors), and can suppress film curl due to heat treatment during touch panel manufacture, and these. This relates to the touch panel used.

  A transparent conductive film in which a transparent thin film with low resistance is laminated on a substrate made of a transparent plastic film is used for applications utilizing the conductivity, for example, a flat such as a liquid crystal display or an electroluminescence (EL) display. Widely used in electrical and electronic fields such as panel displays and transparent electrodes for touch panels.

  In particular, touch panels have rapidly become popular in recent years as input devices that replace key switches. The touch panel includes a fixed electrode (film, sheet, or glass electrode) and a movable electrode (film electrode), and is disposed on the front surface of a display medium such as a liquid crystal display. For this reason, a transparent conductive film in which a hard coat layer is laminated is generally used for the outermost layer of the film electrode used for the movable electrode of the touch panel to prevent scratches.

  However, in recent years, with the further enlargement of screen (larger area) and higher quality, the level of demand for suppression of iris-like colors (interference fringes) under fluorescent lamps has increased. In addition, fluorescent lamps are mainly in the three-wavelength form for daylight color reproducibility, and interference fringes are more easily observed. Therefore, it has been demanded to suppress interference fringes in a transparent conductive film for a touch panel disposed in front of a liquid crystal display element such as a liquid crystal display or a PDA.

  However, when a hard coat layer is provided on the surface of the transparent substrate film, light interference occurs due to a difference in refractive index between the transparent substrate film and the hard coat layer, and interference fringes are generated. For example, in the case of a hard coat film, the difference between the refractive index of the hard coat layer (for example, 1.49 for acrylic resin) and the refractive index of the polyester film for the base material (for example, 1.62 for PET) is large. Iridescent colors (interference fringes) are generated by the interference between the reflected light at the hard coat layer surface (ie, air / hard coat layer interface) and the reflected light at the hard coat layer / polyester film interface. It is considered to be.

  In order to prevent the occurrence of interference fringes, metal oxide fine particles are contained in the hard coat layer to increase the refractive index of the hard coat layer and reduce the difference in refractive index between the hard coat layer and the polyester film of the substrate. A method is disclosed (for example, see Patent Document 1). However, by including metal oxide fine particles in the hard coat layer, the original functions of the hard coat layer, such as transparency, chemical resistance, scratch resistance, and antifouling property, are lowered.

  Furthermore, in the case of a transparent conductive film in which a transparent conductive thin film is provided on the opposite side of the hard coat film of the hard coat film in which metal oxide fine particles are added to the hard coat layer, the transparent conductive property is obtained by heat treatment in the touch panel manufacturing process. Curling occurs in the film, and problems are likely to occur in printing accuracy in the subsequent silver electrode printing process.

  In addition, as another method for suppressing interference fringes in the hard coat layer, paying attention to the variation in the local thickness of the film, after manufacturing an easy-adhesive film, the film is subjected to a calendering treatment to determine the local thickness of the film. A method for reducing the variation in the above has been disclosed (for example, see Patent Document 2). However, the above method evaluates the interference fringes by the film alone, and no investigation is made on the interference fringes based on the difference in the refractive index of the interface when the hard coat layer is laminated, and the production increases because the number of processes increases. There is a problem in terms of sex.

  Moreover, the invention which prescribed | regulated the area ratio of the interference fringe paying attention to the thickness unevenness of the layer which comprises a hard-coat film is disclosed (for example, refer patent document 3). However, the level of thickness spots and the reduction method are not specifically described in the specification. For example, in order to reduce the thickness unevenness of each layer, it is necessary to strictly control the thickness of each layer, which is problematic in terms of productivity or yield.

  Furthermore, focusing on the back surface reflectance of the film itself, a method of laminating a hard coat layer having a specific hardness while suppressing the back surface reflectance is also disclosed (see, for example, Patent Document 4). However, in the method described in Patent Document 4, a coat layer having a specific refractive index and a specific thickness is provided on the opposite surface of the hard coat layer of the hard coat film, and the back surface reflectance is controlled to be 0.1% or less. Must. Therefore, it is necessary to design the film including the back side. In addition, when the film is manufactured, the back surface reflectivity is always controlled to 0.1% or less, and the back surface reflectivity is controlled such as changing the condition when the back surface reflectivity is out of the range while measuring the back surface reflectivity. It is complicated.

JP-A-7-151902 JP 2001-71439 A JP 2002-241527 A JP 2002-210906 A

  In view of the above-mentioned conventional problems, the object of the present invention is excellent in transparency and suppression of interference fringes (iris color) when used in a touch panel, and the film is curled even during heat treatment in the touch panel manufacturing process. It is in providing a transparent conductive film and a touch panel using these.

  In the present invention, paying attention to the refractive index of the intermediate coating layer of the biaxially stretched polyester film used for the hard coat layer and the substrate, the difference in refractive index between the polyester film constituting the substrate and the coating layer, the coating layer and the hard coat The initial adhesion between the base film and the hard coat layer is controlled by controlling the refractive index of the coating layer with the type and content of the resin and additives that make up the coating layer so that the difference in refractive index between the layers is reduced. It has been found that the iris-like color under a fluorescent lamp can be suppressed while maintaining the property and the adhesion (humidity heat resistance) under high temperature and high humidity.

  That is, the transparent conductive film of the present invention comprises a base film having a coating layer, a transparent conductive film formed by laminating a hard coat layer on the surface of the coating layer of the base film and a transparent conductive thin film on the other surface. The base film is a water-based polyester resin (A), a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound After applying and drying an aqueous coating solution having a mixing ratio (mass ratio) of (A) / (B) of 10/90 to 95/5 as at least one of (B) as a main constituent component, at least one It is a biaxially stretched polyester film having a coating layer stretched in the direction.

  Further, the touch panel of the present invention is a touch panel in which a pair of panel plates having the transparent conductive thin film is arranged via a spacer so that the transparent conductive thin film faces each other, and at least one panel plate is the transparent panel It is characterized by comprising a conductive film.

  Since the transparent conductive film of the present invention is excellent in transparency and suppression of iris color and has little film curl even by heat treatment in the touch panel manufacturing process, a touch panel excellent in appearance quality can be manufactured with high yield.

(Base film)
<Biaxially oriented polyester film>
The biaxially stretched polyester film used as a substrate in the present invention is a film composed of a polyester resin, and mainly contains at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate as a constituent component. Among these polyester resins, polyethylene terephthalate is most preferable from the balance between physical properties and cost. Moreover, a polyester film can improve chemical resistance, heat resistance, mechanical strength, etc. by biaxially stretching.

  The biaxially stretched polyester film may be a single layer or a multilayer. These layers can contain various additives in the polyester resin as necessary. Examples of the additive include an antioxidant, a light-resistant agent, an anti-gelling agent, an organic lubricant, an antistatic agent, an ultraviolet absorber, and a surfactant.

  In addition, in order to improve the handling properties such as film slipperiness, rollability and blocking resistance, and wear characteristics such as abrasion resistance and scratch resistance, inert particles are generally added to the polyester film of the base material. It is included. However, since the film is used as a base film of a transparent conductive film, it is required to have excellent handling properties while maintaining high transparency. Specifically, the base film is made highly transparent so that the total light transmittance of the transparent conductive film is preferably 85% or more, particularly preferably 90% or more. The higher the total light transmittance is, the better the transparency is (100% is ideal), but the handling property is lowered and the production at the industrial level becomes difficult. Therefore, the upper limit of the total light transmittance is preferably 96%.

  Therefore, the content of the inert particles in the base film is preferably as small as possible. Therefore, it is preferable to make a multilayer structure in which particles are contained only in the surface layer of the film, or to contain fine particles only in the coating layer without substantially containing particles in the film.

  In particular, from the viewpoint of transparency, when inert particles are not substantially contained in the polyester film, inorganic and / or heat-resistant polymer particles are contained in the aqueous coating solution in order to improve the handleability of the film. It is important to form irregularities on the surface of the coating layer. Note that “substantially no inert particles” means, for example, in the case of inorganic particles, a content which is below the detection limit when quantitatively analyzing the elements derived from the particles by fluorescent X-ray analysis. Means.

<Coating layer>
The transparent conductive film of the present invention is a transparent conductive film formed by laminating a base film having a coating layer, a hard coat layer on the surface of the coating layer of the base film, and a transparent conductive thin film on the other surface. The base film is composed of at least one of the water-based polyester resin (A) and a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound. One type (B) is the main component, and after applying and drying an aqueous coating solution having a mixing ratio (mass ratio) of (A) / (B) of 10/90 to 95/5, at least in one direction It is important that it is a biaxially stretched polyester film having a stretched coating layer. The composition ratio (A / B; mass ratio) of the constituent components (A) and (B) of the coating layer is more preferably 15/85 to 90/10.

  The coating layer is heated with heat during the stretching process of the polyester film, so that at least one of a titanium chelate compound, a titanium acylate compound, a zirconium chelate compound, or a zirconium acylate compound (B) is in contact with the polyester resin. A uniform film is formed by a crosslinking reaction. That is, since the metal chelate compound or metal acylate compound is decomposed by heat treatment, the compound is not present in the coating layer after the heat treatment in a state added to the coating solution.

Therefore, the content of the metal chelate compound or metal acylate compound in the coating solution is calculated from the content of the metal element (Ti or Zr) in the coating layer after the heat treatment as follows.
(1) First, the type of chelate or acylate contained in the coating solution is identified from the chelate or acylate residue in the coating layer.
(2) Next, the content of the metal chelate compound or metal acylate compound in the coating solution is calculated from the content of the metal element (Ti or Zr) in the coating layer.

  The refractive index of the coating layer is higher than that of the polyester resin (A) alone by increasing the composition ratio of at least one of the titanium chelate compound, the titanium acylate compound, the zirconium chelate compound, or the zirconium acylate compound (B). Can also be high. In order to increase the refractive index of the coating layer, it can also be achieved by including metal fine particles in the coating layer. However, by including metal fine particles, the stretchability of the coating layer and the adhesion between the hard coat layer and the substrate film are lowered.

  The polyester resin (A) constituting the coating layer of the base film may have an active site such as a hydroxyl group or a carboxyl group introduced into its molecular chain, but the ester bond site is reversible at high temperatures without any particular introduction. As a result, a cross-linking reaction takes place at an arbitrary location, resulting in a dense film.

  Moreover, in order to give the same crosslinkability with an acrylic resin, it is necessary to introduce a crosslinkable functional group. However, since the refractive index of the acrylic resin itself is low, even when a titanium chelate compound, a titanium acylate compound, a zirconium chelate compound, or a zirconium acylate compound is used in combination, the refractive index is controlled to be the same as that of the coating layer of the present invention. It is difficult.

  Furthermore, since the polyester resin (A), which is a constituent component of the coating layer, is involved in adhesion to the polyester film, the composition ratio (A / B) of the aqueous polyester resin (A) and the compound (B) is 10 When the ratio is less than / 90, the adhesion with the base film is lowered, and the stretchability as a coating layer is lowered, and it is not uniform during stretching. Therefore, the transparency required for optical use decreases, and the adhesion with the hard coat layer formed on the coating layer becomes a problem. On the other hand, when the composition ratio (A / B) between the aqueous polyester resin (A) and the compound (B) exceeds 95/5, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble Crosslinking by the zirconium acylate compound (B) becomes poor, and the refractive index also decreases. For this reason, the adhesion (humidity and heat resistance) under high temperature and high humidity is lowered, and the effect of suppressing iris-like colors under a fluorescent lamp is insufficient.

  The aqueous polyester resin (A) is dissolved or dispersed in water or a water-soluble organic solvent (for example, an aqueous solution containing less than 50% by mass of alcohol, alkyl cellosolve, ketone, or ether). It means a possible polyester resin. In order to impart water resistance to the polyester resin, it is important to introduce a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, or an ether group into the molecular chain of the polyester resin. Among the hydrophilic groups, sulfonic acid groups are preferable from the viewpoint of coating film properties and adhesion.

  When the sulfonic acid group is introduced into the polyester, the sulfonic acid compound is more preferably 1 to 10 mol% in the total acid component of the polyester. When the amount of the sulfonic acid group is less than 1 mol%, the polyester resin does not exhibit water, and a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound Since the compatibility with at least one of (B) also decreases, it becomes difficult to obtain a uniform and transparent coating layer. Moreover, when the amount of sulfonic acid group exceeds 10 mol%, it becomes easy to be inferior to the adhesiveness (humidity heat resistance) under high temperature and high humidity.

  Further, the aqueous polyester resin (A) preferably has a glass transition temperature of 40 ° C. or higher. For this reason, the acid component of the polyester resin (A) is preferably composed mainly of an aromatic group such as terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid. The glycol component is preferably a glycol having a relatively small carbon number such as ethylene glycol, propane glycol, 1,4-butanediol, or neopentyl glycol, or an aromatic system such as an ethylene oxide adduct of bisphenol A. Further, as a raw material of the polyester resin (A), a rigid component such as biphenyl or a dicarboxylic acid component or diol component having a high refractive index atom such as bromine or sulfur may be used within a range in which the physical properties of the film do not deteriorate. Good. When the glass transition temperature of the polyester resin (A) is less than 40 ° C., the adhesiveness (humidity heat resistance) under high temperature and high humidity tends to be insufficient. Furthermore, since the refractive index of the polyester resin (A) also decreases, the refractive index of the coating layer also decreases. As a result, the suppression of iris color under fluorescent lamps tends to be insufficient.

  The other main component of the coating layer is at least one (B) of a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble zirconium acylate compound. The above water-soluble means to dissolve in water or an aqueous solution containing less than 50% by mass of a water-soluble organic solvent.

  Examples of water-soluble titanium chelate compounds include diisopropoxybis (acetylacetonato) titanium, isopropoxy (2-ethyl-1,3-hexanediolato) titanium, diisopropoxybis (triethanolaminato) titanium, di -N-butoxybis (triethanolaminato) titanium, hydroxybis (lactato) titanium, ammonium salt of hydroxybis (lactato) titanium, ammonium beloxocitrate ammonium salt and the like.

  Examples of the water-soluble titanium acylate compound include oxotitanium bis (monoammonium oxalate), and examples of the water-soluble zirconium compound include zirconium tetraacetylacetonate and zirconium acetate.

  In the coating layer, a resin other than the main component, for example, an acrylic resin, a polyurethane resin, a polyester resin, an alkyd resin, a vinyl resin such as polyvinyl alcohol, etc. is used in a range that does not affect the effect of the present invention. It doesn't matter. Further, the combined use of the crosslinking agent is not particularly limited as long as the effect of the present invention is not affected. Examples of crosslinking agents that can be used include adducts of urea, melamine, benzoguanamine, and the like with formaldehyde, amino resins such as alkyl ether compounds composed of these adducts and alcohols having 1 to 6 carbon atoms, polyfunctional epoxy compounds, Examples thereof include a polyfunctional isocyanate compound, a blocked isocyanate compound, a polyfunctional aziridine compound, and an oxazoline compound.

  In the present invention, the coating liquid used for forming the coating layer includes an aqueous polyester resin (A), a water-soluble titanium chelate compound, a water-soluble titanium acylate compound, a water-soluble zirconium chelate compound, or a water-soluble It is an aqueous coating liquid mainly composed of at least one zirconium acylate compound (B) and an aqueous solvent. When applying the above aqueous coating solution to the surface of the polyester film, an appropriate amount of a known anionic surfactant or nonionic surfactant is added to improve the wettability of the film and coat the coating solution uniformly. It is preferable to do.

  In addition, in the aqueous coating solution, inorganic and / or heat-resistant polymer particles, antistatic agents, ultraviolet absorbers, etc. in order to impart other functions such as handling properties, antistatic properties and antibacterial properties to the film. Additives such as organic lubricants, antibacterial agents, and photo-oxidation catalysts can be included.

  As the solvent used in the coating solution, alcohols such as ethanol, isopropyl alcohol, and benzyl alcohol may be mixed in addition to water in a range of less than 50% by mass with respect to the total coating solution. Furthermore, if it is less than 10 mass%, you may mix in the range which can melt | dissolve organic solvents other than alcohol. However, the total amount of alcohols and other organic solvents in the coating solution is preferably less than 50% by mass.

<Manufacture of base film>
The method for producing an easily-adhesive polyester film that becomes the base material of the transparent conductive film of the present invention will be described by taking a polyethylene terephthalate (hereinafter sometimes abbreviated as PET) film as an example, but it is naturally limited to this. It is not a thing.

  After sufficiently drying the PET resin in a vacuum, it is supplied to an extruder, melted and extruded at about 280 ° C. from a T-die into a rotating cooling roll into a sheet, cooled and solidified by an electrostatic application method, and unstretched PET. Get a sheet. The unstretched PET sheet may have a single layer structure or a multilayer structure by a coextrusion method. As described above, the polyester film constituting the base film is a multi-layer structure composed of at least three layers, and only the base intermediate layer contains an ultraviolet absorber, and the ultraviolet absorber in both surface layers is not substantially contained. Is preferred. Moreover, it is preferable not to contain an inert particle substantially in PET resin.

  The obtained unstretched PET sheet is stretched 2.5 to 5.0 times in the longitudinal direction with a roll heated to 80 to 120 ° C. to obtain a uniaxially stretched PET film. Furthermore, the edge part of a film is hold | gripped with a clip, it guide | induces to the hot air zone heated at 70-140 degreeC, and is extended | stretched 2.5 to 5.0 times in the width direction. Then, it guide | induces to the heat processing zone of 160-240 degreeC, and heat-processes for 1 to 60 seconds, and completes crystal orientation.

  In any stage of the film production process, the aqueous coating solution is applied to at least one surface of the PET film. The coating layer may be formed on both sides of the PET film. The solid content concentration of the resin composition in the aqueous coating solution is preferably 2 to 35% by mass, particularly preferably 4 to 15% by mass.

  As a method for applying this aqueous coating solution to a PET film, any known method can be used. For example, reverse roll coating method, gravure coating method, kiss coating method, die coater method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, curtain coating method, etc. These methods are applied alone or in combination.

  In the present invention, it is important that the coating layer is formed by applying the aqueous coating solution to an unstretched or uniaxially stretched PET film, drying it, stretching it at least uniaxially, and then performing a heat treatment. The film coated with the coating solution is guided to a tenter and heated for transverse stretching and heat treatment. At that time, the chelate compound or the acylate compound can form a stable crosslinked coating layer by a thermal crosslinking reaction. On the other hand, in the case of a coating layer obtained by applying and drying the coating solution on a biaxially stretched PET film, the heat amount is suppressed in order to reduce the deterioration of the transparency of the polyester film due to heat treatment and the change in physical properties. I must. Therefore, the amount of heat is insufficient to perform the thermal crosslinking reaction, and a uniform crosslinked coating layer cannot be formed.

In the present invention, the coating amount of the finally obtained coating layer is preferably 0.02 to 0.5 g / m ² . If the coating amount of the coating layer is less than 0.02 g / m ² , not only the effect on adhesiveness is almost lost, but also the effect of suppressing iris-like colors under a fluorescent lamp tends to be insufficient. On the other hand, when the coating amount exceeds 0.5 g / m ² , the effect of suppressing the iris color under a fluorescent lamp tends to be insufficient.

  In the present invention, the coating layer is formed by the so-called in-line coating method in which the coating layer is formed in the production process of the polyester film in order to develop the adhesion layer and the function of suppressing interference fringes in the coating layer. is important. The in-line coating method can be processed at a higher temperature than the off-line coating method, improves durability adhesion with the hard coat layer, and is advantageous in terms of economy. In addition, since it is an in-line coating method, after coating, the coating film is stretched to reduce the thickness of the coating film, so there is an advantage that variation in coating film thickness due to variation in coating amount is suppressed compared to the offline coating method. . In the present invention, the effect of reducing interference fringes greatly varies due to variations in the thickness of the coating film. Therefore, there is an advantage that interference fringes can be stably reduced by suppressing the thickness variation of the coating film by the in-line coating method.

(Hard coat layer)
The transparent conductive film of the present invention has a laminated structure consisting of hard coat layer / intermediate coating layer 1 / biaxially stretched polyester film / transparent conductive thin film. Also, hard coat layer / intermediate coating layer 1 / biaxially stretched polyester film / cured product layer / transparent conductive thin film, or hard coat layer / intermediate coating layer 1 / biaxially stretched polyester film / intermediate coating layer 2 / cured product layer / Laminated conductive thin film may be used. The constituent components of the intermediate coating layer 2 may be the same as those of the intermediate coating layer 1, or other resins having an easy adhesion layer may be used. A functional layer such as an antireflection layer or an antifouling layer may be laminated on the surface of the hard coat layer.

  The hard coat layer is provided to improve the scratch resistance of the outermost layer (pen input surface) when a touch panel is used. In the present invention, a hard coat layer is provided on the coating layer surface of the base film on the surface opposite to the surface on which the transparent conductive thin film of the biaxially stretched polyester film is formed (the outermost pen input surface when used as a touch panel). Is preferred. The hard coat layer preferably has a pencil hardness of 2H or more. When the hardness is less than 2H, the hard coat layer of the transparent conductive film is insufficient in terms of scratch resistance.

  The thickness of the hard coat layer is preferably 0.5 to 10 μm. If the thickness is less than 0.5 μm, the scratch resistance tends to be insufficient, and if it is thicker than 10 μm, it is not preferable from the viewpoint of productivity.

  The curable resin used for the hard coat layer is preferably a resin having an acrylate functional group, for example, a relatively low molecular weight polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin. And oligomers or prepolymers such as (meth) acrylates of polyfunctional compounds such as spiroacetal resins, polybutadiene resins, polythiol polyene resins and polyhydric alcohols.

  Reactive diluents include monofunctional monomers such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone, and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate. , Hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) ) Those containing a relatively large amount of acrylate, neopentyl glycol di (meth) acrylate, etc. can be used.

  In the present invention, it is preferable to mix urethane acrylate as an oligomer and dipentaerythritol hexa (meth) acrylate as a monomer.

  As the curable resin used for the hard coat layer, a mixture of polyester acrylate and polyurethane acrylate is particularly suitable. Polyester acrylate is suitable as a constituent resin for the hard coat layer because the coating film is very hard. However, a coating film made of a resin of polyester acrylate alone has a problem that it has a low impact resistance and tends to become brittle. Therefore, in order to give impact resistance and flexibility to the coating film, it is preferable to use polyurethane acrylate together. That is, by using polyurethane acrylate together with polyester acrylate, the coating film can have functions of impact resistance and flexibility while maintaining the hardness as a hard coat layer.

  The blending ratio of both is preferably 30 parts by mass or less of the polyurethane acrylate resin with respect to 100 parts by mass of the polyester acrylate resin. When the blending ratio of the polyurethane acrylate resin exceeds 30 parts by mass, the coating film becomes too soft and the impact resistance tends to be insufficient.

  The curing method of the curable resin composition may be a normal curing method, that is, a method of curing by heating, electron beam or ultraviolet irradiation. For example, in the case of electron beam curing, 50 to 1000 keV emitted from various electron beam accelerators such as Cockloft Walton type, handicograph type, resonance transformation type, insulation core transformer type, linear type, dynamitron type, and high frequency type. Preferably, an electron beam having an energy of 100 to 300 keV is used. In the case of ultraviolet curing, ultraviolet rays emitted from light rays such as an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp can be used.

  Furthermore, in the case of ionizing radiation curing, it is preferable to include a photopolymerization initiator or a photosensitizer in the curable resin composition. Examples of the photopolymerization initiator include acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetramethylthiuram monosulfide, and thioxanthones. Moreover, as a photosensitizer, n-butylamine, triethylamine, tri-n-butylphosphine, etc. are preferable.

(Anti-glare treatment of hard coat layer)
In order to impart antiglare properties to the hard coat layer, it is generally performed to form an uneven shape on the surface of the hard coat layer by dispersing inorganic particles such as CaCO ₃ and SiO ₂ in a curable resin. Is called. However, in such a hard coat layer containing inorganic particles, film curl is likely to occur due to heat treatment in the touch panel manufacturing process, as in the case of containing particles for the purpose of improving the refractive index. In order to impart antiglare properties to the hard coat layer while suppressing curling of the film, it is preferable to laminate and form a shaped film having a convex shape on the surface. For example, after applying a coating liquid containing a curable resin composition, a shaped film having a convex shape is laminated on the surface, and after irradiating ultraviolet rays on the shaped film to cure the curable resin, shaping is performed. The method of peeling only a film is mentioned.

  The moldable film has a desired convex shape on a base film such as polyethylene terephthalate (hereinafter abbreviated as PET) having releasability, or a fine film on a base film such as PET. What formed the convex layer etc. can be used. Formation of the convex layer can be obtained, for example, by coating on a base film using a resin composition comprising inorganic particles and a binder resin.

As the binder resin, for example, an acrylic polyol cross-linked with polyisocyanate can be used, and as the inorganic particles, CaCO ₃ , SiO ₂ or the like can be used. In addition, mat-type PET in which inorganic particles such as SiO ₂ are kneaded at the time of PET production can also be used.

  When this shaped film is laminated on a coating film of an ultraviolet curable resin and then the coating film is cured by irradiating with ultraviolet rays, when the shaping film is a PET-based film, the ultraviolet light has a short wavelength side. There is a drawback that the UV curable resin is absorbed and insufficiently cured. Therefore, it is necessary to use a moldable film that is laminated on the UV curable resin coating film having a total light transmittance of 20% or more.

(Transparent conductive thin film)
The transparent conductive thin film used in the present invention is not particularly limited as long as it is a material having both transparency and conductivity, but indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide. And those having a single layer or a laminated structure of two or more layers, such as an oxide, a zinc-aluminum complex oxide, an indium-zinc complex oxide, silver and a silver alloy, copper and a copper alloy, and gold. Of these, indium-tin composite oxide or tin-antimony composite oxide is preferable from the viewpoint of environmental stability and circuit processability.

  The thickness of the transparent conductive thin film is preferably in the range of 4 to 800 nm, particularly preferably 5 to 500 nm. When the thickness of the transparent conductive thin film is less than 4 nm, it tends to be difficult to form a continuous thin film and to exhibit good conductivity. On the other hand, when it is thicker than 800 nm, the transparency tends to decrease.

  As a method for forming a transparent conductive thin film in the present invention, a vacuum vapor deposition method, a sputtering method, a CVD method, an ion plating method, a spray method, and the like are known. Can be used as appropriate.

  For example, in the case of the sputtering method, a normal sputtering method using an oxide target, a reactive sputtering method using a metal target, or the like is used. At this time, oxygen, nitrogen, or the like may be introduced as a reactive gas, or means such as ozone addition, plasma irradiation, or ion assist may be used in combination. In addition, a bias such as direct current, alternating current, and high frequency may be applied to the substrate as long as the object of the present invention is not impaired.

(Underlayer)
Moreover, in order to improve the adhesiveness of a transparent conductive thin film and a film base material, it is preferable to provide the hard material layer which consists of curable resin between a transparent conductive thin film and a film base material. The curable resin is not particularly limited as long as it is a resin that is cured by application of energy such as heating, ultraviolet irradiation, electron beam irradiation, etc., such as silicone resin, acrylic resin, methacrylic resin, epoxy resin, melamine resin, polyester resin, urethane resin, etc. Is mentioned. From the viewpoint of productivity, it is preferable to use an ultraviolet curable resin as a main component.

  Examples of such ultraviolet curable resins are synthesized from polyfunctional acrylate resins such as acrylic acid or methacrylic acid ester of polyhydric alcohol, diisocyanate, polyhydric alcohol and hydroxyalkyl ester of acrylic acid or methacrylic acid. Such polyfunctional urethane acrylate resins can be mentioned. If necessary, a monofunctional monomer such as vinyl pyrrolidone, methyl methacrylate, or styrene can be added to these polyfunctional resins for copolymerization.

  In order to improve the adhesion between the transparent conductive thin film and the cured product layer, it is effective to surface-treat the cured product layer. As a specific method, using a discharge treatment method irradiating glow or corona discharge, a method for increasing carbonyl group, carboxyl group, hydroxyl group, a chemical treatment method using acid or alkali treatment, an amino group, And a method of increasing polar groups such as a hydroxyl group and a carbonyl group.

  The ultraviolet curable resin is usually used by adding a photopolymerization initiator. As the photopolymerization initiator, known compounds that absorb ultraviolet rays and generate radicals can be used without particular limitation. Examples of such photopolymerization initiators include various benzoins, phenyl ketones, and benzophenones. And the like. The addition amount of the photopolymerization initiator is preferably 1 to 5 parts by mass per 100 parts by mass of the ultraviolet curable resin.

  Moreover, it is preferable that the hardened | cured material layer used by this invention uses together incompatible polymer resin with curable resin other than curable resin which is a main component. By using a small amount of an incompatible resin together with the matrix curable resin, phase separation occurs in the curable resin, and the incompatible resin can be dispersed in the form of particles. By forming irregularities due to the dispersed particles of this incompatible resin on the surface of the cured product layer, irregularities can be given to the transparent conductive thin film surface, and slipperiness between the glass surface and the transparent conductive thin film surface during pen input Is improved. As a result, pen sliding durability can be improved.

  When the curable resin is the ultraviolet curable resin, examples of the incompatible resin include polyester resin, polyolefin resin, polystyrene resin, and polyamide resin.

  The polyester resin preferably has a high molecular weight of 5,000 to 50,000 in terms of weight average molecular weight. The lower limit value of the average molecular weight is particularly preferably 8,000, and the upper limit value is particularly preferably 30,000. If the weight average molecular weight of the polyester resin is less than 5,000, the polyester resin tends to be difficult to disperse as particles of an appropriate size in the cured product layer. On the other hand, when the weight average molecular weight of the polyester resin exceeds 50,000, it is not preferable because the solubility in a solvent is lowered when a coating solution is prepared.

  The high molecular weight polyester resin is an amorphous saturated polyester resin obtained by polymerizing a dihydric alcohol and a divalent carboxylic acid, and can be dissolved in the same solvent as the ultraviolet curable resin. Is.

  Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, and 1,4-cyclohexanedimethanol. And hydrogenated bisphenol A.

  Examples of the divalent carboxylic acid include isophthalic acid, terephthalic acid, adipic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and the like.

  In addition, trivalent or higher alcohols such as trimethylolpropane or pentaerythritol, and trivalent or higher carboxylic acids such as trimellitic anhydride or pyromellitic anhydride, as long as the solubility in the solvent does not become insufficient. Can be copolymerized.

  In the present invention, when an ultraviolet curable resin is used as a curable resin that is a main component of the cured product layer, and a high molecular weight polyester resin is used as a non-compatible polymer resin for the curable resin, the blending ratio thereof is The polyester resin is preferably 0.1 to 20 parts by mass per 100 parts by mass of the ultraviolet curable resin. The upper limit of the compounding ratio of the polyester resin is more preferably 10 parts by mass, particularly preferably 5 parts by mass. Further, the lower limit of the compounding ratio of the polyester resin is more preferably 0.2 parts by mass, particularly preferably 0.5 parts by mass.

  When the blending ratio of the polyester resin is less than 0.1 parts by mass per 100 parts by mass of the ultraviolet curable resin, the protrusions formed on the surface of the cured product layer are reduced or the protrusions tend to decrease, and the pen sliding The effect of further improving durability is not exhibited, which is not preferable. On the other hand, when the compounding amount of the polyester resin exceeds 20 parts by mass per 100 parts by mass of the ultraviolet curable resin, the strength of the cured product layer is lowered and the chemical resistance tends to be deteriorated.

  However, since the refractive index of the polyester resin is different from that of the ultraviolet curable resin, it is not preferable because it tends to increase the haze value of the cured product layer and deteriorate the transparency. On the contrary, it can be used as an antiglare film having a high haze value and an antiglare function by actively utilizing the deterioration of transparency caused by dispersed particles of a high molecular weight polyester resin.

  The UV curable resin, photopolymerization initiator and high molecular weight polyester resin are dissolved in a common solvent to prepare a coating solution. The solvent to be used is not particularly limited, and examples thereof include alcohol solvents such as ethyl alcohol and isopropyl alcohol, ester solvents such as ethyl acetate and butyl acetate, dibutyl ether, and ethylene glycol monoethyl ether. Ether solvents, ketone solvents such as methyl isobutyl ketone and cyclohexanone, and aromatic hydrocarbon solvents such as toluene, xylene and solvent naphtha can be used alone or in combination.

  The concentration of the resin component in the coating solution can be appropriately selected in consideration of the viscosity according to the coating method. For example, the ratio of the total amount of the ultraviolet curable resin, the photopolymerization initiator and the high molecular weight polyester resin in the coating solution is usually 20 to 80% by mass. Moreover, you may add another well-known additive, for example, a silicone type leveling agent, etc. to this coating liquid as needed.

  In the present invention, the prepared coating solution is coated on a biaxially stretched polyester film substrate. The coating method is not particularly limited, and conventionally known methods such as a bar coating method, a gravure coating method, and a reverse coating method can be used.

  In the coated coating solution, the solvent is removed by evaporation in the next drying step. In this step, the high molecular weight polyester resin that has been uniformly dissolved in the coating solution becomes fine particles and precipitates in the ultraviolet curable resin. After drying the coating film, the plastic film is irradiated with ultraviolet rays, whereby the ultraviolet curable resin is crosslinked and cured to form a cured product layer. In this curing step, fine particles of the high molecular weight polyester resin are fixed in the hard coat layer, and protrusions are formed on the surface of the cured product layer.

  Moreover, it is preferable that the thickness of a hardened | cured material layer is the range of 0.1-15 micrometers. The lower limit of the thickness of the cured product layer is more preferably 0.5 μm, and particularly preferably 1 μm. Further, the upper limit value of the thickness of the cured product layer is more preferably 10 μm, and particularly preferably 8 μm. When the thickness of the cured product layer is less than 0.1 μm, the protrusions are not easily formed. On the other hand, when it exceeds 15 μm, it is not preferable from the viewpoint of productivity.

(Optical interference layer)
In order to change the transmittance, color, and reflectance of the transparent conductive film, it is preferable to provide at least two layers having different refractive indexes between the transparent conductive thin film and the transparent plastic film. For example, when two layers having different refractive indexes are provided, a high refractive index layer having a refractive index of 1.60 to 2.5 and a low refractive index layer having a refractive index of 1.3 to 1.6 from the transparent plastic film side. Are laminated.

The high refractive index layer having a refractive index of 1.60 or more and 2.5 or less is composed of an inorganic material or a mixture of an organic material and an inorganic material. As the inorganic material, transparent metal oxides such as In ₂ O ₃ , TiO ₂ , and Nb ₂ O ₅ are generally used.

  The layer made of a mixture of an organic substance and an inorganic substance contains a cured resin and a metal oxide by ionizing radiation and has a refractive index in the range of 1.60 to 1.80 (hereinafter, this layer is referred to as a high refractive layer). If the refractive index is less than 1.60, it is difficult to obtain a transparent conductive film excellent in antireflection performance, and the object of the present invention cannot be achieved. Moreover, it is difficult to form a layer having a refractive index exceeding 1.80. A preferred refractive index is in the range of 1.70 to 1.80.

  The metal oxide is not particularly limited as long as a layer having a refractive index in the range of 1.60 to 1.80 can be obtained. In order to further improve the transmittance of the transparent conductive film, It is preferable that the adhesiveness with the layer provided on it is excellent. From this point, the metal oxide is not particularly limited as long as the above conditions are satisfied. For example, when the low refractive layer is a siloxane polymer, antimony-doped tin oxide (ATO), tin oxide Etc. can be mentioned preferably. These metal oxides may be used individually by 1 type, and may be used in combination of 2 or more type.

The low refractive index layer having a refractive index of 1.3 or more and 1.6 or less is also composed of an organic substance, an inorganic substance, or a mixture of an organic substance and an inorganic substance. In general, transparent metal oxides such as SiO ₂ and Al ₂ O ₃ are used as the inorganic substance.

  The organic material includes at least one of siloxane-based polymer, polyurethane, polyester, and acrylic from the viewpoint of adhesion to the transparent conductive thin film, and has a refractive index in the range of 1.30 to 1.55. is there. When deviating from the refractive index, it is difficult to obtain a transparent conductive film excellent in transparency.

  In order to further improve the transmittance of visible light, an optical interference layer may be provided on the hard coat layer. The optical interference layer is preferably formed by laminating a material having a refractive index different from that of the hard coat layer in a single layer or two or more layers.

In the case of providing a single layer structure, it is preferable to use a material having a refractive index smaller than that of the hard coat layer. In the case of a multilayer structure of two or more layers, a material having a higher refractive index than that of the hard coat layer is used for the layer adjacent to the hard coat layer, and the upper layer has a lower refractive index. It is better to choose the material. The material constituting such a low reflection treatment is not particularly limited as long as the above refractive index relationship is satisfied, whether it is an organic material or an inorganic material. For example, it is preferable to use _{CaF 2, MgF 2, NaAlF 4} , SiO 2, ThF 4, ZrO 2, Nd 2 O 3, SnO 2, TiO 2, CeO 2, ZnS, In 2 O 3, a dielectric such as .

  The optical interference layer may be a dry coating process such as a vacuum deposition method, a sputtering method, a CVD method, or an ion plating method, or a wet coating process such as a gravure method, a reverse method, or a die method.

  Further, prior to the lamination of the optical interference layer, known surface treatments such as corona discharge treatment, plasma treatment, sputter etching treatment, electron beam irradiation treatment, ultraviolet ray irradiation treatment, primer treatment, and easy adhesion treatment are performed as pretreatment. You may give to a coat layer.

  EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. The performance of the transparent conductive film was measured by the following method.

(1) Surface resistivity It measured by the 4-terminal method based on JIS-K7194. As a measuring machine, Lotest AMCP-T400 manufactured by Mitsubishi Yuka Co., Ltd. was used.

(2) Light transmittance and haze Based on JIS-K7105, light transmittance and haze were measured using NDH-1001DP by Nippon Denshoku Industries Co., Ltd.

(3) Glass transition temperature In accordance with JIS K7121, using a differential scanning calorimeter (DSC6200, manufactured by Seiko Instruments Inc.), the temperature was raised at a rate of 20 ° C / min over a temperature range of 25 to 300 ° C. The obtained extrapolated glass transition start temperature was defined as the glass transition temperature.

(4) Color (a value, b value)
In accordance with JIS-K7105, color a and b values were measured with a standard light C / 2 using a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., ZE-2000).

(5) Curling by heat treatment The transparent conductive film was cut into an area of 40 cm × 40 cm to prepare a sample film. The obtained sample film was heat-treated in an oven at 135 ± 3 ° C. for 30 minutes with the transparent conductive thin film side up. After the heat treatment, the film was taken out from the oven and allowed to cool at room temperature for 30 minutes with the transparent conductive thin film surface facing up. Then, the height of the maximum curled portion of the film was measured and used as the curl value.

(6) Interference fringe improvement (iris color)
The transparent conductive film was cut into an area of 10 cm (film width direction) × 15 cm (film longitudinal direction) to prepare a sample film. A black glossy tape (manufactured by Nitto Denko Corporation, vinyl tape No21; black) was bonded to the transparent conductive thin film surface of the obtained sample film. With the hard coat surface of the sample film as the top surface, the positional relationship where the reflection is the strongest visually observed from diagonally above using a three-wavelength daylight white color (National Palook, FL 15EX-N 15W) as a light source (distance 40 to distance from the light source) (60 cm, angle of 15 to 45 °).

The results of visual observation are ranked according to the following criteria. The observation is performed by five people who are familiar with the evaluation, and the highest rank is the evaluation rank. If two ranks have the same number, the center of the rank divided into three is adopted. For example, ◎ and ○ are 2 people each and △ is 1 person, ○ is ◎, ◎ is 1 person and ○ and △ are 2 people each, ○, ◎ and △ are 2 people each and ○ is 1 In the case of names, ○ is adopted.
◎: Iridescent colors are not observed even when observed from any angle ○: Some iris colors are observed depending on the angle △: Slightly iris colors are observed ×: Obvious iris colors are observed Be done

(7) Adhesive force measurement A 40 μm thick ionomer film was laminated to a 75 μm thick polyethylene terephthalate film with a polyester adhesive to prepare a laminate for measuring an adhesive force. The ionomer surface of this laminate for measuring adhesive force and the transparent conductive thin film surface of the transparent conductive film were opposed to each other and heat sealed at 130 ° C. The laminate was peeled from the laminate for measuring adhesive force and the transparent conductive film by a 180 ° peeling method, and this peeling force was defined as the adhesive force. The peeling speed at this time was 1000 mm / min.

(8) Pen sliding durability test A 5.0 N load was applied to a polyacetal pen (tip shape: 0.8 mmR), and a linear sliding test was performed 200,000 times (100,000 reciprocations) on the touch panel. . The sliding distance at this time was 30 mm, and the sliding speed was 60 mm / second. After this sliding durability test, first, it was visually observed whether the sliding portion was whitened. Furthermore, a symbol “o” of 20 mmφ was written so as to be applied to the sliding portion with a pen load of 0.5 N, and it was evaluated whether the touch panel could be read accurately. Furthermore, the ON resistance (resistance value when the movable electrode (film electrode) and the fixed electrode were in contact) when the sliding portion was pressed with a pen load of 0.5 N was measured.

(Polyester resin polymerization)
In a stainless steel autoclave equipped with a stirrer, a thermometer, and a partial reflux condenser, 186 parts by mass of dimethyl terephthalate, 186 parts by mass of dimethyl isophthalate, 23.7 parts by mass of dimethyl 5-sodium sulfoisophthalate, neopentyl glycol 137 parts by mass, 191 parts by mass of ethylene glycol, and 0.5 parts by mass of tetra-n-butyl titanate were charged, and a transesterification reaction was performed from 160 ° C to 220 ° C over 4 hours. Next, the temperature was raised to 255 ° C., and the pressure of the reaction system was gradually reduced, followed by reaction for 1 hour 30 minutes under a reduced pressure of 29 Pa to obtain a copolymerized polyester resin (A-1). The obtained copolyester resin was light yellow and transparent.

  In the same manner, a copolyester resin (A-2) having another composition was obtained. Table 1 shows the results of the composition and weight average molecular weight measured by NMR for these copolyester resins.

Example 1
(1) Preparation of polyester aqueous dispersion In a reactor equipped with a stirrer, a thermometer and a reflux device, 20 parts by mass of polyester resin (A-1) and 15 parts by mass of ethylene glycol monobutyl ether are added and heated at 100 ° C. , Stirred to dissolve the resin. After the resin was completely dissolved, 65 parts by mass of water was gradually added to the polyester solution while stirring. After the addition, the solution was cooled to room temperature while stirring to prepare an aqueous dispersion (B-1) of milky white polyester having a solid content of 20% by mass. Similarly, a polyester resin (A-2) was used instead of the polyester resin (A-1) to prepare an aqueous dispersion, which was used as an aqueous dispersion (B-2).

(2) Preparation of coating liquid 40 parts by mass of the obtained polyester aqueous dispersion (B-1), 44 parts by mass of hydroxybis (lactato) titanium (manufactured by Matsumoto Pharmaceutical Co., Ltd., TC310) 18 parts by mass, water 150 1 part by mass of spherical anionic surfactant (Neopelex No6F powder; dodecylbenzenesulfonate) manufactured by Kao Corporation and 1 part by mass of the coating solution, respectively. (Catalyst Kasei Kogyo Co., Ltd., Cataloid SI80P; average particle size 80 nm) An aqueous dispersion was added in an amount of 2% by mass as silica to the resin solids to prepare a coating solution (hereinafter abbreviated as coating solution (C-1)). .

(3) Manufacture of an easily adhesive polyester film (base film) having a coating layer As a film raw material polymer, an intrinsic viscosity of 0.62 dl / g and PET resin pellets substantially free of particles are 133 Pa. It dried for 6 hours at 135 degreeC under pressure reduction. Thereafter, it is supplied to a twin-screw extruder, melted and extruded into a sheet form at about 280 ° C., rapidly cooled and solidified by an electrostatic application method on a rotating cooling metal roll maintained at a surface temperature of 20 ° C. A stretched PET sheet was obtained.

  This unstretched PET sheet was heated to 100 ° C. with a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction with a roll group having a difference in peripheral speed to obtain a uniaxially stretched PET film.

Next, the coating solution (C-1) was coated on one side of the PET film by a reverse roll method so that the coating amount after drying was 0.5 g / m ^2, and then dried at 80 ° C. for 20 seconds. After drying, the film was stretched 4.0 times in the width direction at 120 ° C with a tenter, and heated at 230 ° C for 0.5 seconds with the length in the width direction fixed, and further at 230 ° C. A relaxation treatment in the width direction of 3% was performed for 10 seconds to obtain a biaxially stretched PET film having a coating layer on one side having a thickness of 188 μm.

(4) Production of hard coat film To 100 parts by mass of photopolymerization initiator-containing acrylic resin (manufactured by Dainichi Seika Kogyo Co., Ltd., Seika Beam EXF-01J), a mixed solvent of toluene / MEK (8/2: mass ratio) as a solvent. The solution was added so that the solid concentration was 50% by mass, and stirred to dissolve uniformly to prepare a coating solution.

The prepared coating solution was applied to the coating surface of the base film using a Mayer bar so that the thickness of the coating film was 5 μm. After drying at 80 ° C. for 1 minute, the coating film was cured by irradiating with ultraviolet rays (light quantity: 300 mJ / cm ² ) using an ultraviolet irradiation device (manufactured by Eye Graphics, UB042-5AM-W type).

(Method for producing transparent conductive film)
In a hard coat film formed by laminating a hard coat layer on one side, a transparent conductive thin film made of indium-tin composite oxide was formed on the opposite side of the hard coat layer by the following method. The pressure before sputtering was 0.0001 Pa, and a DC power of ² W / cm ² was applied to indium oxide containing 5% by mass of tin oxide as a target (Mitsui Metal Mining Co., Ltd., density 7.1 g / cm ³ ). . Further, Ar gas was flowed at 130 sccm and O ₂ gas was flowed at a flow rate of 10 sccm, and a film was formed by DC magnetron sputtering in an atmosphere of 0.4 Pa. However, in order to prevent arc discharge instead of normal DC, a pulse with a width of 5 μs was applied at a frequency of 50 kHz using an RPG-100 manufactured by Nippon NI. The center roll temperature was 50 ° C. and sputtering was performed.

  In addition, while constantly monitoring the oxygen partial pressure of the atmosphere with a sputter process monitor (manufactured by Hakuto, SPM200), an oxygen gas flow meter and a DC power source are used so that the degree of oxidation in the indium-tin composite oxide thin film becomes constant. I'm back. As described above, a transparent conductive thin film made of an indium-tin composite oxide having a thickness of 22 nm was deposited.

<Production of touch panel>
This transparent conductive film is used as one panel plate, and the other panel plate is composed of an indium-tin composite oxide thin film (tin oxide content: 10% by mass) having a thickness of 20 nm by plasma CVD on a glass substrate. A transparent conductive thin film (Nippon Soda, S500) was used. The two panel plates were arranged through epoxy beads having a diameter of 30 μm so that the transparent conductive thin film faced to prepare a touch panel.

Example 2
48 parts by mass of polyester aqueous dispersion (B-2), 44 parts by mass of hydroxybis (lactato) titanium (manufactured by Matsumoto Pharmaceutical Co., Ltd., TC310) 15 parts by mass, 150 parts by mass of water and 100 parts by mass of isopropyl alcohol Furthermore, 1% by mass of an anionic surfactant (Neopelex No6F powder; dodecylbenzenesulfonate; manufactured by Kao Corporation) and spherical colloidal silica fine particles (catalyst chemical industry, Cataloid SI80P; average) (A particle size of 80 nm) An aqueous dispersion was added in an amount of 2% by mass as silica with respect to the resin solid content to prepare a coating solution (hereinafter abbreviated as coating solution (C-2)).
In Example 1, except that only the coating solution is changed to the coating solution (C-2), a biaxially stretched PET film having a coating layer on one side, a hard coat film, and a transparent conductive material are the same as in Example 1. A characteristic film was obtained.

Example 3
A hard coat film having a hard cord layer on one side was obtained by the following method on the coating layer of the base film obtained in the same manner as in Example 1.
As a hard coat layer resin, an ultraviolet curable resin (EXG, manufactured by Dainichi Seika Kogyo Co., Ltd.) made of a mixture of polyester acrylate and polyurethane acrylate is applied by a gravure reverse method so that the film thickness after drying is 5 μm. Dried. Next, a mat-shaped shaped film (X, manufactured by Toray, Inc.), a PET film having a fine convex shape formed on the surface, was laminated so that the mat surface was in contact with the ultraviolet curable resin. The surface shape of this mat shaped film is an average surface roughness of 0.40 μm, an average crest distance of 160 μm and a maximum surface roughness of 25 μm.

  The laminated film was passed under a 160 W ultraviolet irradiation device at a speed of 10 m / min to cure the ultraviolet curable resin. Next, the mat-shaped film was peeled off to form a hard coat layer having a concave shape on the surface and having an antiglare effect.

  In the hard coat film in which the antiglare hard coat layer is provided on one surface of the base film via the coating layer, the indium-tin composite oxide is formed on the opposite surface of the hard coat layer in the same manner as in Example 1. The physical thin film was formed as a transparent conductive thin film. Furthermore, a touch panel was produced in the same manner as in Example 1 using this transparent conductive film as one panel plate.

Example 4
In Example 1, a hard coat film composed of a hard coat layer / base film (coating layer / biaxially oriented transparent PET film) was coated with polyester acrylate and polyurethane acrylate as a cured layer resin on the opposite side of the hard coat layer surface. An ultraviolet curable resin (EXG, manufactured by Dainichi Seika Kogyo Co., Ltd.) made of a mixture was applied by a gravure reverse method so that the film thickness after drying was 5 μm, and the solvent was dried. Then, it passed under the 160 W ultraviolet irradiation device at a speed of 10 m / min to cure the ultraviolet curable resin and form a cured product layer. Next, heat treatment was performed at 180 ° C. for 1 minute to reduce volatile components.

  An indium-tin composite oxide thin film was formed on the cured product layer of the laminate composed of this hard coat layer / base film (coating layer / biaxially oriented transparent PET film) / cured product layer in the same manner as in Example 1. Filmed. Furthermore, using this transparent conductive film, a touch panel was produced in the same manner as in Example 1.

Example 5
In the same manner as in Example 1, a transparent conductive film comprising a hard coat layer / base material film (coating layer / biaxially oriented transparent PET film) / transparent conductive thin film layer was produced. Next, a TiO ₂ thin film layer (refractive index: 2.30, film thickness 15 nm), SiO ₂ thin film layer (refractive index: 1.46, film thickness 29 nm), TiO ₂ thin film layer (refractive) are sequentially formed on the hard coat layer. An antireflection layer formed by laminating SiO ₂ thin film layers (refractive index: 1.46, film thickness 87 nm) was formed.

The TiO ₂ thin film layer was formed by direct current magnetron sputtering using titanium as a target, with a degree of vacuum of 0.27 Pa, and by flowing Ar gas at a flow rate of 500 sccm and O ₂ gas at a flow rate of 80 sccm. Note that a cooling roll having a surface temperature of 0 ° C. was provided on the back surface of the substrate to cool the transparent plastic film. Further, 7.8 W / cm ² of electric power was supplied to the target, and the dynamic rate was set to 23 nm · m / min.

The SiO ₂ thin film was formed by direct current magnetron sputtering using silicon as a target, with a degree of vacuum of 0.27 Pa, an Ar gas of 500 sccm as a gas, and an O ₂ gas of 80 sccm. In addition, the 0 degreeC cooling roll was provided in the back surface of the board | substrate, and the transparent plastic film was cooled. Further, 7.8 W / cm ² of electric power was supplied to the target, and the dynamic rate was set to 23 nm · m / min. Furthermore, a touch panel was produced in the same manner as in Example 1 using this transparent conductive film as one panel plate.

Example 6
TiO ₂ -containing acrylic hard coating agent (manufactured by JSR, Desolite Z7252D, solid content concentration: 45% by mass, TiO ₂ : acrylic resin = 75: 25 (mass ratio)) so that the solid content concentration becomes 3% by mass A coating agent was prepared by diluting with a mixed solvent of methyl isobutyl ketone and isopropyl alcohol in a mass ratio of 1: 1.

After completely curing this coating agent on a cured product layer of a laminate comprising a hard coat / substrate film (coating layer / biaxially oriented transparent PET film) / cured product layer produced in the same manner as in Example 4 The film was applied to a thickness of 70 nm and dried at 80 ° C. for 1 minute. Subsequently, this was irradiated with ultraviolet rays at a light amount of 80 mJ / cm ² to be cured in a half-cured state, thereby forming a high refractive layer.

Furthermore, a fluorine-containing siloxane-based coating agent (Shin-Etsu Chemical Co., Ltd., X-12-2138H, solid content concentration: 3% by mass) and a photopolymerization initiator-containing acrylic resin (Daiichi Seika Kogyo, Seika Beam EXF-01J) Was added so that the total solid concentration was 6% by mass to obtain a coating solution for forming a hard coat layer. Next, the coating solution was applied on the high refractive index layer so that the thickness after the heat treatment was 20 nm, and dried at 80 ° C. for 1 minute. Subsequently, ultraviolet rays were irradiated (light quantity: 300 mJ / cm ² ) using an ultraviolet ray irradiation device (UB042-5AM-W type, manufactured by Eye Graphics), and further heat-treated at 150 ° C. for 1 minute to have a refractive index of 1.48. The low refractive index layer was formed. Further, a transparent conductive thin film layer was formed in the same manner as in Example 1 to obtain a transparent conductive film.

Example 7
In Example 1, a transparent conductive film was obtained in the same manner as in Example 1 except that the film thicknesses of the high refractive index layer and the low refractive index layer were 90 nm and 45 nm, respectively.

Comparative Example 1
A metal oxide sol composed of SnO ₂ and WO ₃ (manufactured by Nissan Chemical Co., AMT-130S, solid content concentration: 30% by mass) and xylene of an ultraviolet curable siloxane-based acrylate resin (manufactured by Shin-Etsu Chemical Co., Ltd., X-12-2400) With respect to resin of a dilution liquid (solid content concentration: 30 mass%), it mix | blended so that the total amount of a metal oxide might be 60 mass%, and it was set as the coating liquid for hard-coat layer formation. Next, on the easy-adhesion layer of a biaxially oriented transparent PET film (Toyobo, A4140, thickness 188 μm) having an easy-adhesion layer on one side, the above-mentioned coating solution is added to the Meyer so that the thickness of the coating film becomes 5 μm. It apply | coated using the bar | burr and dried for 1 minute at 80 degreeC. Furthermore, ultraviolet rays were irradiated (light quantity: 300 mJ / cm ² ) using an ultraviolet irradiation device (manufactured by Eye Graphics, UB042-5AM-W type), and the coating film was cured to obtain a hard coat film. Further, a transparent conductive layer was formed on the surface opposite to the hard coat layer side by the same method as in Example 1 to obtain a transparent conductive film.

Comparative Example 2
On the easy-adhesion layer of a biaxially oriented transparent PET film (Toyobo, A4140, thickness 188 μm) having an easy-adhesion layer on one side, a hard coat layer is formed in the same manner as in Example 1 to obtain a hard-coat film. It was. Furthermore, a transparent conductive layer was formed on the surface opposite to the hard coat layer by the same method as in Example 1 to obtain a transparent conductive film.

Comparative Example 3
A hard coat layer is formed on both sides of a biaxially stretched PET film (Toyobo Co., Ltd., A4340, thickness 188 μm) having an easy-adhesion layer on both sides produced by the same method as in Example 1 in the same manner as in Comparative Example 1. Formed. Furthermore, a transparent conductive thin film was formed on one side of the hard coat film by the same method as in Example 1 to obtain a transparent conductive film.

  From the results of Table 2, the touch panel using the transparent conductive film described in Examples 1 to 8 satisfying the scope of the present invention is excellent in transparency and has improved interference fringes under a fluorescent lamp. Furthermore, curling of the film due to heat treatment could be suppressed.

  On the other hand, in the configuration in which the metal oxide fine particles were added to the hard coat layer (Comparative Example 1), although there was an effect of suppressing interference fringes, the film was curled by heat treatment. In the configuration (Comparative Example 3) in which hard coat layers containing metal oxide fine particles are provided on both sides in order to suppress curling of the film due to heat treatment, the transparent conductive film can prevent curling due to heat treatment, but surface resistivity. Increased. Furthermore, a touch panel was produced, and the input symbol “◯” was not accurately recognized, so that practically sufficient performance could not be satisfied. Moreover, when the specific coating layer described in the present invention was not provided as the coating layer of the base film (Comparative Example 2), the interference fringe reduction effect was not observed.

  The transparent conductive film of the present invention is excellent in transparency, particularly when used for a touch panel, can suppress interference fringes (iris-like colors), and can suppress film curl due to heat treatment during touch panel manufacture. Therefore, it is useful as a transparent electrode of a touch panel used for a liquid crystal display element such as a liquid crystal display or a PDA, particularly as a movable electrode (film electrode) used on the front surface.

Claims (4)

  A base film having a coating layer, a transparent conductive film formed by laminating a hard coat layer on the surface of the coating layer of the base film and a transparent conductive thin film on the other surface, wherein the base film is , Water polyester resin (A), water-soluble titanium chelate compound, water-soluble titanium acylate compound, water-soluble zirconium chelate compound, or water-soluble zirconium acylate compound (B) Biaxially having a coating layer stretched in at least one direction after applying and drying an aqueous coating solution having a mixing ratio (mass ratio) of (A) / (B) of 10/90 to 95/5 as a component A transparent conductive film film, which is a stretched polyester film.   The transparent conductive film according to claim 1, wherein the transparent conductive film has a total light transmittance of 80% or more.   3. The transparent conductive film according to claim 1, wherein the transparent conductive thin film is an indium-tin composite oxide or a tin-antimony composite oxide.   The transparent touch panel according to any one of claims 1 to 3, wherein a pair of panel plates having the transparent conductive thin film are arranged via a spacer so that the transparent conductive thin film faces each other. A touch panel comprising a conductive film.