JP2014225405A - Transparent conductive film and resistance film-type touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film that improves decrease in visibility caused by an interference color (i.e., a mottled rainbow) when viewing an image display device through a polarization film such as sunglasses.SOLUTION: A transparent conductive film has a transparent conductive membrane put on at least one face of a transparent plastic film base material, the transparent plastic film base material having a retardation of 3000 nm-30000 nm.

Description

  The present invention relates to a transparent conductive film in which a transparent conductive film is laminated on a transparent plastic film substrate, in particular, a transparent conductive film and a resistance film type that are excellent in visibility even through sunglasses when used for a touch panel used outdoors or the like. It relates to a touch panel. In particular, when used in a resistive touch panel for pen input, it has excellent pen sliding durability.

  A transparent conductive film obtained by laminating a transparent thin film with low resistance on a transparent plastic substrate is used for applications utilizing the conductivity, for example, flat panel displays such as liquid crystal displays and electroluminescence (EL) displays, As a transparent electrode of a touch panel, it is widely used for applications in the electric / electronic field.

  With the spread of portable information terminals, notebook computers with touch panels, and car navigation systems, displays with touch panels used outdoors have increased. For this reason, the opportunity to visually recognize a liquid crystal display through polarizing filters, such as sunglasses, is increasing. When a commercially available general-purpose film that is generally distributed is incorporated into a liquid crystal display as a base film for a transparent conductive film, strong interference colors may appear when the screen of the liquid crystal display is observed through sunglasses. It was.

Moreover, in the touch panel used for such a display, the touch panel excellent in pen sliding durability is requested | required. When a pen is input to the touch panel, the transparent conductive thin film on the fixed electrode side and the transparent conductive thin film on the movable electrode (film electrode) side come into contact with each other. At this time, the transparent conductive thin film is cracked or peeled off by the pen load. There is a demand for a transparent conductive film having excellent pen sliding durability that does not break.
As means for improving pen sliding durability, there is a method in which the transparent conductive thin film on the movable electrode (film electrode) side is made crystalline (Patent Documents 1 to 11).

However, the conventional transparent conductive film has the following problems.
Patent Documents 1 to 7 are transparent conductive films in which a base layer generated by hydrolysis of an organic silicon compound is provided on a transparent plastic film substrate, and a crystalline transparent conductive thin film is further formed. However, these transparent conductive films use the polyacetal pen described in the pen sliding durability test described later, and after 300,000 linear sliding tests at a load of 5.0 N, the transparent conductive thin film As a result of peeling, the whitening occurred and the durability against pen sliding was insufficient.

  Patent Documents 8 to 11 are transparent conductive films characterized in that a crystalline transparent conductive thin film is formed by extremely reducing water in a film forming atmosphere during sputtering. However, in order to produce these transparent conductive films, it is necessary to perform evacuation for a long time or a vacuum pump having a very high capacity, which is not suitable for industrial use. Moreover, the transparent conductive film of patent document 11 uses the pen made from polyacetal as described in the below-mentioned pen sliding durability test, and after 300,000 linear sliding tests with a load of 5.0 N, the transparent conductive film As a result of peeling of the conductive thin film, it was whitened, and the durability against pen sliding was insufficient.

JP 60-131711 A JP-A 61-79647 JP-A-61-183809 Japanese Patent Laid-Open No. 2-194943 JP-A-2-276630 JP-A-8-64034 Japanese Patent Laid-Open No. 11-286078 Japanese Unexamined Patent Publication No. 2000-144379 JP 2000-238178 A JP 2004-71171 A International Publication WO2000 / 051139

  In view of the above-described conventional problems, an object of the present invention is to provide a transparent conductive material that improves a decrease in visibility due to an interference color (that is, rainbow spots) when an image display device is viewed through a polarizing film such as sunglasses. To provide a film. In addition, it has excellent pen sliding durability when used for touch panels, especially using a polyacetal pen, and transparent conductive film that does not break the transparent conductive thin film even after 300,000 sliding tests at a load of 5.0 N To provide a film.

This invention is made | formed in view of the above situations, Comprising: The transparent conductive film of this invention which was able to solve said subject consists of the following structures.
Item 1.
A transparent conductive film having a transparent conductive film laminated on at least one surface on a transparent plastic film substrate, wherein the retardation of the transparent plastic film substrate is 3000 nm to 30000 nm.
Item 2.
The transparent conductive film is made of indium oxide, the crystal grain size of the indium oxide is 30 to 1000 nm, and the ratio of the amorphous part to the crystalline part of the transparent conductive film is 0.00 to 0.50. Item 2. The transparent conductive film according to Item 1, wherein:
Item 3.
Item 3. The transparent conductive film according to Item 2, wherein the transparent conductive film further contains 0.5 to 8% by mass of tin oxide.
Item 4.
Item 4. The transparent conductive film according to any one of Items 1 to 3, wherein the transparent conductive film has a thickness of 10 to 100 nm.
Item 5.
Item 5. A resistive touch panel using the transparent conductive film according to any one of Items 1 to 4.

ADVANTAGE OF THE INVENTION According to this invention, the fall of the image quality represented by the rainbow when it visually recognizes through a polarizing filter is reduced, and the visibility of layer display apparatuses, such as a liquid crystal display, is improved. In this document, “rainbow spot” is a concept including “color spot”, “color shift”, and “interference color”. Moreover, according to a preferable aspect, a transparent conductive film having very excellent pen sliding durability is obtained, which is extremely useful for applications such as a touch panel for pen input.

It is the figure which showed the example (the 1) regarding the longest part of the crystal grain of this invention. It is the figure which showed the example (the 2) regarding the longest part of the crystal grain of this invention. It is the figure which showed the example (the 3) regarding the longest part of the crystal grain of this invention. It is the figure which showed the example (the 4) regarding the longest part of the crystal grain of this invention.

  The transparent conductive film of the present invention is a transparent conductive film in which a transparent conductive film is laminated on at least one surface on a transparent plastic film substrate, and the retardation of the transparent plastic film substrate is 3000 nm to 30000 nm.

<Transparent plastic film substrate>
The transparent plastic film substrate used in the present invention is preferably a high retardation oriented film.

<Retardation of oriented film>
The retardation of the high retardation oriented film is preferably 3000 nm or more and 30000 nm or less from the viewpoint of reducing rainbow spots. The lower limit value of the retardation of the high retardation oriented film is preferably 4500 nm or more, preferably 6000 nm or more, preferably 8000 nm or more, preferably 10,000 nm or more. On the other hand, the upper limit of the retardation of the high retardation oriented film is that even if an oriented film having a retardation higher than that is used, the effect of improving the visibility is not substantially obtained, and the orientation depends on the height of the retardation. Since the thickness of the film also tends to increase, it is set to 30000 nm from the viewpoint that it may be contrary to the demand for thinning, but it can be set to a higher value. When the image display device has two or more high retardation alignment films, the retardations may be the same or different.

  From the standpoint of more effectively suppressing rainbow spots, the high retardation oriented film has a ratio (Re / Rth) of the retardation (Re) and thickness direction retardation (Rth) of preferably 0.2 or more, Preferably it is 0.5 or more, preferably 0.6 or more. Thickness direction retardation means an average value of retardation obtained by multiplying two birefringences ΔNxz and ΔNyz by film thickness d when viewed from a cross section in the film thickness direction. As Re / Rth is larger, the birefringence action is more isotropic, and the generation of rainbow spots on the screen can be more effectively suppressed. In this document, when simply described as “retardation”, it means in-plane retardation.

  The maximum value of Re / Rth is 2.0 (that is, a perfect uniaxial symmetry film), but the mechanical strength in the direction perpendicular to the orientation direction tends to decrease as the perfect uniaxial symmetry film is approached. is there. Therefore, the upper limit of Re / Rth of the polyester film is preferably 1.2 or less, and preferably 1.0 or less. Even if the ratio is 1.0 or less, it is possible to satisfy the viewing angle characteristics (180 degrees left and right, 120 degrees up and down) required for the image display device.

  The retardation of the oriented film can be measured according to a known method. Specifically, it can be determined by measuring the refractive index and thickness in the biaxial direction. Moreover, it can also obtain | require using the commercially available automatic birefringence measuring apparatus (For example, KOBRA-21ADH: Oji Scientific Instruments Co., Ltd. make).

  When a high retardation alignment film is used by incorporating it in an image display device such as a liquid crystal display, the angle formed by the alignment principal axis of the high retardation alignment film and the polarization axis of the viewing side polarizer (the high retardation alignment film and the polarizer are Is assumed to be on the same plane), but is not particularly limited, but is preferably close to 45 degrees from the viewpoint of reducing the rainbow. For example, the angle is preferably 45 ° ± 25 ° or less, and preferably 45 ° ± 20 ° or less. In particular, the angle is preferably 45 ° ± 15 from the viewpoint of reducing rainbow spots when the image display device is observed from an oblique direction through a polarizing film such as sunglasses, and making the angle dependency of the low retardation alignment film smaller. Or less, preferably 45 ° ± 10 ° or less, preferably 45 ° ± 5 ° or less, preferably 45 ° ± 3 ° or less, 45 ° ± 2 ° or less, 45 ° ± 1 ° or less, 45 °. In this document, the term “below” means that only the value following “±” is applied. That is, “45 degrees ± 15 degrees or less” means that a fluctuation in the range of 15 degrees above and below 45 degrees is allowed.

  Arranging the high retardation alignment film so as to satisfy the above conditions is, for example, a method of arranging the cut high retardation alignment film such that the alignment main axis is at a specific angle with the polarizer, or high retardation. It can be performed by a method of arranging the alignment film so as to be at a specific angle with the polarizer by obliquely stretching.

The high retardation alignment film can be produced by appropriately selecting a known method. For example, high retardation alignment films include polyester resins, polycarbonate resins, polystyrene resins, syndiotactic polystyrene resins, polyether ether ketone resins, polyphenylene sulfide resins, cycloolefin resins, liquid crystalline polymer resins, and cellulosic resins. It can be produced using one or more selected from the group consisting of added resins. Therefore, high retardation alignment film is a polyester film, polycarbonate film, polystyrene film, syndiotactic polystyrene film, polyetheretherketone film, polyphenylene sulfide film, cycloolefin film, liquid crystalline film, and liquid crystal compound added to cellulose resin. Film.

The preferred raw material resin for the high retardation oriented film is polycarbonate, polyester or syndiotactic polystyrene. These resins are excellent in transparency and excellent in thermal and mechanical properties, and the retardation can be easily controlled by stretching. Polyesters typified by polyethylene terephthalate and polyethylene naphthalate are preferable because they have a large intrinsic birefringence, and relatively large retardation can be obtained even when the film thickness is thin. In particular, polyethylene naphthalate has a large intrinsic birefringence among polyesters, and therefore is suitable for a case where it is desired to make the retardation particularly high or a case where it is desired to reduce the film thickness while keeping the retardation high. A more specific method for producing a high retardation oriented film will be described later using a polyester resin as a representative example.

<Method for producing high retardation oriented film>
Below, the manufacturing method of a highly retardation orientation film is demonstrated to a polyester film as an example. The polyester film can be obtained by condensing an arbitrary dicarboxylic acid and a diol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and diphenylcarboxylic acid. Acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalate Acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, Dimer , It may be mentioned sebacic acid, suberic acid, dodecamethylene dicarboxylic acid.

  Examples of the diol include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1,3-propanediol, 1,4 -Butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone and the like can be mentioned.

  Each of the dicarboxylic acid component and the diol component constituting the polyester film may be used alone or in combination of two or more. Specific polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc., preferably polyethylene terephthalate and polyethylene naphthalate, preferably polyethylene terephthalate. . The polyester resin may contain other copolymer components. From the viewpoint of mechanical strength, the proportion of the copolymer components is preferably 3 mol% or less, preferably 2 mol% or less, more preferably 1.5 mol% or less. . These resins are excellent in transparency and excellent in thermal and mechanical properties. Moreover, retardation of these resins can be easily controlled by stretching.

  The polyester film can be obtained according to a general production method. Specifically, the polyester resin is melted and the non-oriented polyester extruded and formed into a sheet shape is stretched in the longitudinal direction by utilizing the speed difference of the roll at a temperature equal to or higher than the glass transition temperature, and then in the transverse direction by a tenter. An oriented polyester film is mentioned by extending | stretching and heat-processing. The polyester film may be a uniaxially stretched film or a biaxially stretched film. The high retardation oriented film may be stretched at an angle of 45 degrees.

  Manufacturing conditions for obtaining a polyester film can be appropriately set according to a known method. For example, the longitudinal stretching temperature and the transverse stretching temperature are usually 80 to 130 ° C, preferably 90 to 120 ° C. The longitudinal draw ratio is usually 1.0 to 3.5 times, preferably 1.0 to 3.0 times. The transverse draw ratio is usually 2.5 to 6.0 times, preferably 3.0 to 5.5 times.

  Controlling the retardation within a specific range can be performed by appropriately setting the stretching ratio, stretching temperature, and film thickness. For example, it becomes easier to obtain a higher retardation as the stretching ratio between the longitudinal stretching and the lateral stretching is higher, the stretching temperature is lower, and the film is thicker. On the contrary, it becomes easier to obtain a lower retardation as the stretching ratio between the longitudinal stretching and the lateral stretching is lower, the stretching temperature is higher, and the film thickness is thinner. Moreover, the higher the stretching temperature and the lower the total stretching ratio, the easier it is to obtain a film having a lower ratio of retardation to thickness direction (Re / Rth). Conversely, a film having a higher ratio of retardation to thickness direction retardation (Re / Rth) can be obtained as the stretching temperature is lower and the total stretching ratio is higher. Furthermore, the heat treatment temperature is usually preferably 140 to 240 ° C, and preferably 180 to 240 ° C.

  In order to suppress the fluctuation of the retardation in the polyester film, it is preferable that the thickness unevenness of the film is small. If the longitudinal stretching ratio is lowered to make a retardation difference, the value of the longitudinal thickness unevenness may be increased. Since there is a region where the value of the vertical thickness unevenness becomes very high in a specific range of the draw ratio, it is desirable to set the film forming conditions so as to exclude such a range.

The thickness unevenness of the oriented polyester film is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and 3.0% or less. It is particularly preferred. The thickness unevenness of the film can be measured by any means. For example, a tape-like sample (length 3 m) continuous in the film flow direction is collected, and 100 cm at a 1 cm pitch using a commercially available measuring instrument (for example, an electronic micrometer Millitron 1240 manufactured by Seiko EM Co., Ltd.). The thickness of the point is measured, the maximum value (dmax), the minimum value (dmin), and the average value (d) of the thickness are obtained, and the thickness unevenness (%) can be calculated by the following formula.
Thickness unevenness (%) = ((dmax−dmin) / d) × 100

  The thickness of the transparent plastic film substrate used in the present invention is preferably in the range of 15 to 300 μm, more preferably 20 to 260 μm, and particularly preferably 70 to 260 μm. Even in the case of a film having a thickness of less than 15 μm, a retardation of 3000 nm or more can be obtained in principle. However, in that case, the anisotropy of the mechanical properties of the film becomes remarkable, and it becomes easy to cause tearing, tearing, etc., and the practicality as an industrial material is remarkably lowered. On the other hand, when the thickness exceeds 300 μm, the pen load for deforming the film tends to increase when used for a touch panel, which is not preferable.

  The transparent plastic film substrate used in the present invention has a surface activity such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, ozone treatment, etc., as long as the object of the present invention is not impaired. The treatment may be performed.

  When a curable resin layer is applied to a transparent plastic film substrate and the surface of the curable resin layer is made uneven, and a transparent conductive film is formed thereon, an improvement in pen sliding durability can be expected. There are two main effects. The first point is that the adhesion between the transparent conductive thin film and the curable resin layer is increased, so that the transparent conductive film can be prevented from being peeled off by the sliding of the pen, and the pen sliding durability is improved. The second point is that the true contact area when the transparent conductive thin film comes into contact with the glass is reduced by sliding the pen, and the sliding property between the glass surface and the transparent conductive film is improved, so that the pen sliding durability is improved. It is. Details of the curable resin layer are described below.

<Curable resin layer>
In addition, the curable resin used in the present invention 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, and the like. Silicone resin, acrylic resin, methacrylic resin, epoxy resin, melamine resin , Polyester resin, urethane resin and the like. 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 a polyfunctional urethane acrylate resin can be used. If necessary, a monofunctional monomer such as vinyl pyrrolidone, methyl methacrylate, styrene or the like can be added to these polyfunctional resins for copolymerization.

  In order to improve the adhesion between the transparent conductive thin film and the curable resin layer, it is effective to surface-treat the surface of the curable resin layer. Specific methods include a discharge treatment method in which glow or corona discharge is applied to increase carbonyl groups, carboxyl groups, and hydroxyl groups, and acids or alkalis to increase polar groups such as amino groups, hydroxyl groups, and carbonyl groups. The chemical treatment method etc. to process are mentioned.

  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.

  In the present invention, it is preferable to use a resin that is incompatible with the curable resin in addition to the curable resin, which is the main component, in the curable resin layer. 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. With the dispersed particles of the incompatible resin, irregularities can be formed on the surface of the curable resin, and the surface roughness in a wide region can be improved.

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

  In the present invention, when an ultraviolet curable resin is used as a curable resin which is a main component of the curable resin layer, and a high molecular weight polyester resin is used as a polymer resin incompatible with the curable resin, the blending ratio thereof Is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 10 parts by weight, and particularly preferably 0.5 to 5 parts by weight per 100 parts by weight of the ultraviolet curable resin.

  When the blending amount of the polyester resin is less than 0.1 parts by mass per 100 parts by mass of the ultraviolet curable resin, the convex part formed on the surface of the curable resin layer tends to be small or the convex part tends to decrease. The roughness is not improved, and a further improvement effect of pen sliding 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 curable resin layer is lowered and the chemical resistance is easily deteriorated.

  However, since the polyester resin has a difference in refractive index from that of the ultraviolet curable resin, the haze value of the curable resin layer tends to increase and the transparency tends to be deteriorated, so that it needs to be used with caution. 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 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, 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 and the like 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 transparent plastic 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 curable resin 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 curable resin layer to improve the surface roughness in a wide region.

  The thickness of the curable resin layer is preferably in the range of 0.1 to 15 μm. More preferably, it is the range of 0.5-10 micrometers, Most preferably, it is the range of 1-8 micrometers. When the thickness of the curable resin 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.

(Transparent conductive film)
The transparent conductive film in the present invention is made of an inorganic material such as indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, indium-zinc composite oxide. And conductive polymers such as polyaniline, polypyrrole, polyacetylene, polythiophene, PEDOT: poly (3,4-ethylenedioxythiophene), or ultrafine conductive carbon fibers such as carbon nanotubes, carbon nanohorns, and carbon nanowires are dispersed in the polymer. And graphene. Of these, indium-tin composite oxides are preferable from the viewpoints of environmental stability and circuit processability.

The transparent conductive film is a transparent conductive film mainly composed of crystalline indium oxide, the crystal grain size of indium oxide is 30 to 1000 nm, and the ratio of the amorphous part to the crystalline part of the transparent conductive film Is preferably 0.00 to 0.50.

Here, the definition of the crystal grain size of indium oxide in the transparent conductive film is as follows.
For the crystal grains of indium oxide observed in the transparent conductive film layer under a transmission electron microscope, the longest part of all the crystal grains is measured, and the average value of the measured values is taken as the crystal grain size. Here, the example regarding the longest part of a crystal grain is shown in FIGS.
Further, a method for estimating the ratio of the amorphous part to the crystalline part is calculated from the area ratio of the crystalline part and the amorphous part when observed under a transmission electron microscope.

  The crystal grain size of indium oxide in the transparent conductive film of the present invention is preferably 30 to 1000 nm. Especially preferably, it is 35-800 nm. When the crystal grain size is smaller than 30 nm, the pen sliding durability is deteriorated because the bonding force between the crystal grains is weak. On the contrary, when the crystal grain size exceeds 1000 nm, the bending resistance deteriorates, so that the flexibility is lowered and the meaning of forming a transparent conductive film on the plastic film substrate is remarkably lost.

The ratio of the amorphous part to the crystalline part of indium oxide in the transparent conductive film of the present invention is preferably 0.00 to 0.50, more preferably 0.00 to 0.45. When the ratio is larger than 0.50, the crystal grains are in an island shape in the amorphous part. In such a state, when the pen sliding durability test is performed, the amorphous part is first peeled off, and the crystal grain is also peeled off by using the part as a trigger, thereby destroying the transparent conductive film.
If the ratio is 0.50 or less, the crystal grains are not floating in the form of islands in the amorphous part, and the crystal grains are all connected. In such a state, even if the pen sliding durability test is performed, the crystal grains support each other, so that a pen sliding durability is extremely high.

  In the manufacturing method of the transparent conductive film of this invention, it is desirable to heat-process at 80-150 degreeC for 0.1 to 12 hours in the atmosphere containing oxygen. The significance of the heat treatment is to control the size of crystal grains. When the heating temperature and time are increased, crystal grains grow. Since the crystal grains do not grow at a temperature lower than 80 ° C., it does not contribute to improvement of pen sliding durability. If the temperature is higher than 200 ° C., it becomes difficult to maintain the flatness of the transparent plastic film, and further, the crystal grains grow too much, and a large stress is generated between the crystal grains, so that the pen sliding durability is deteriorated.

In order to obtain the transparent conductive film of the present invention, the following methods [1], [2], and [3] are desirable.
[1] In a method for forming a transparent conductive film mainly composed of crystalline indium oxide on at least one surface on a transparent plastic film substrate, the ratio of moisture pressure to inert gas in the film forming atmosphere during sputtering is 8.0 × 10 ^{−4 to} 3.0 × 10 ⁻³ , oxygen partial pressure is set to 8.0 × 10 ⁻³ to 30 × 10 ⁻³ Pa, and the film temperature is set to 80 ° C. or less during film formation. It is desirable to hold and form a transparent conductive film on the transparent plastic film.

It is known that when water is contained in the film formation atmosphere, the crystallization of the transparent conductive film is hindered. Therefore, the amount of moisture in the film formation atmosphere is an important factor. In order to control the amount of water when forming a film on a plastic film, it is desirable to actually observe the amount of water during film formation. Using the ultimate vacuum to control the amount of water in the film formation atmosphere is inappropriate as described below.
First, when a film is formed on a plastic film by sputtering, the film is heated and the amount of water in the film forming atmosphere increases, which is higher than the amount of water when the ultimate vacuum is measured.

  The second point is the case of an apparatus that puts a large amount of transparent plastic film. In such an apparatus, the film is loaded by a roll. When a film is rolled and put into a vacuum chamber, water easily escapes from the outside of the roll, but water does not easily escape from the inside of the roll. When the ultimate vacuum is measured, the film roll is stopped, but the film roll travels during film formation, so that the inner part of the roll containing a lot of water is unwound, so moisture in the film formation atmosphere The amount increases and exceeds the amount of water when the ultimate vacuum is measured. In the present invention, in controlling the amount of moisture in the film forming atmosphere, the ratio of the water pressure to the inert gas in the film forming atmosphere during sputtering is measured.

The ratio of the moisture pressure to the inert gas in the film formation atmosphere during sputtering is desirably as low as possible. However, in an apparatus in which a large amount of transparent plastic film is introduced into the film formation chamber, the ratio to the inert gas as described in Patent Document 11 is used. In order to make the water pressure ratio 2.5 × 10 ^{−6 to} 7.0 × 10 ⁻⁴ , it is necessary to carry out a vacuum for a long time or a highly efficient vacuum pump is required, which is economical. Implementation becomes difficult.

The present invention has a crystalline part in the ratio of moisture pressure to inert gas that can be easily realized even in an apparatus that puts a large amount of transparent plastic film into a film forming chamber, and has excellent pen sliding durability. I found a manufacturing method. The ratio of the moisture pressure to the inert gas is 8.0 × 10 ^{−4 to} 3.0 × 10 ⁻³ that can be easily realized. In this state, when the film is formed with an oxygen partial pressure of 8.0 × 10 ⁻³ to 30 × 10 ⁻³ Pa, a transparent conductive film having a crystalline part can be formed, and the pen sliding durability is excellent. A transparent conductive film can be obtained.

The range of the oxygen partial pressure is very unique. In general, a transparent conductive film is produced at an oxygen partial pressure at which the resistance value is the lowest. However, the present invention is characterized in that the film is formed at an oxygen partial pressure higher than that at which the resistance value is the lowest. .
The intention of increasing the oxygen partial pressure is as follows. When the film is formed with a high oxygen partial pressure, the oxygen deficient portion of indium oxide is compensated, so that a film having a crystal structure that is very energetically stable can be obtained.
As a result, the probability of generation of crystal grains on the transparent plastic substrate is increased, and further, crystal growth is facilitated, so that very excellent pen sliding durability is exhibited. However, if the oxygen partial pressure is higher than 30 × 10 ⁻³ Pa, the surface resistance exceeds a practical level, which is not desirable. Here, a practical level of surface resistance is about 50 to 1000 Ω / □.

  Further, it is desirable to form a transparent conductive film on the substrate while keeping the substrate temperature at 80 ° C. or lower during film formation. When the temperature exceeds 80 ° C., a large amount of impurity gas such as water and organic gas is generated from the film. Therefore, a transparent conductive film having a crystalline part, that is, a transparent conductive film having excellent pen sliding durability is formed. Inhibit.

[2] In order to form a transparent conductive film mainly composed of crystalline indium oxide on at least one surface of a transparent plastic film substrate, an activation support method such as an ion assist method or an ion plating method or a high It is desirable to form a transparent conductive film on the film using a power impulse magnetron sputtering method. In order to form crystal grains, the energy of evaporated atoms is necessary.

In the above method, the energy of the evaporated atom is larger than that of the normal film formation method, so the probability of crystal grain generation and the crystal growth are facilitated. To do. The film formation conditions were as follows: oxygen was introduced at 4.0 × 10 ^{−3 to} 6.0 × 10 ⁻² Pa, argon gas was introduced to bring the film formation pressure to 0.15 Pa, discharge voltage 80 V, Hearth potential It is desirable to perform arc discharge at + 40V and a discharge current of 120A.

[3] When a transparent conductive film mainly composed of crystalline indium oxide is formed on at least one surface of a transparent plastic film substrate by sputtering or the like, the transparent conductive film is formed on the side where the transparent conductive film is formed. It is desirable to apply a coat layer containing fine particles with a diameter of 20 to 500 nm having the same composition as the conductive film. Since the fine particles serve as the nucleus of crystal growth of the transparent conductive film, the growth of crystal grains is promoted, and very excellent pen sliding durability is exhibited. Fine particles having a diameter smaller than 20 nm are difficult to produce and obtain.
Further, when fine particles having a diameter larger than 500 nm are used, crystal grains grow excessively, and thus protrusions are likely to occur when a transparent conductive film is formed. In some cases, the crystal grains are peeled off by the projections, and the transparent conductive thin film is destroyed. The fine particles are desirably used by being dispersed in a curable resin layer applied to a transparent plastic film. However, it is desirable that the fine particles are contained in a proportion of 1 to 30% by mass with respect to the total amount of organic components such as the curable resin layer.

The transparent conductive film of the present invention is mainly composed of indium oxide and desirably contains 0.5 to 8% by mass of tin oxide. Tin oxide is equivalent to impurity addition to indium oxide. Due to the addition of tin oxide impurities, the melting point of indium oxide containing tin oxide increases. That is, the addition of tin oxide impurities acts in the direction of inhibiting crystallization. As for tin oxide, it is desirable to contain 0.5-8 mass%. When tin oxide is less than 0.5%, crystallization occurs, but the total light transmittance is lower than a practical level, and the surface resistance is higher than a practical level, which is not desirable. When tin oxide is larger than 8% by mass, crystallization is difficult and pen sliding durability is deteriorated.
The total light transmittance of the transparent conductive film of the present invention is preferably 70 to 95%, and the surface resistance is preferably 50 to 1000Ω / □.

  In the present invention, the thickness of the transparent conductive film is preferably 10 to 100 nm. When the thickness of the transparent conductive film is less than 10 nm, the film becomes non-uniform, and the pen sliding durability is weakened. Moreover, since the total light transmittance will become lower than a practical level when the thickness of a transparent conductive film becomes thicker than 100 nm, it is not desirable.

(Image display devices such as liquid crystal displays)
The transparent conductive film of the present invention can be suitably used as a transparent conductive film for a touch panel, particularly a transparent conductive film for a resistive film type touch panel. The image display device typically includes a viewing side polarizing plate, an image display cell (liquid crystal cell), a light source side polarizing plate, and a backlight light source in order from the viewing side. Although the touch panel using the transparent conductive film of this invention can be arrange | positioned in the arbitrary places in an image display apparatus, it can arrange | position to the visual recognition side rather than the visual recognition side polarizing plate, for example.

(Backlight light source)
Moreover, it is preferable that an image display apparatus has a white light source which has a continuous and broad emission spectrum as a backlight light source from a viewpoint of suppressing a rainbow spot. The method and structure of the light source having a continuous and broad emission spectrum are not particularly limited, and may be, for example, an edge light method or a direct type. “Continuous and broad emission spectrum” means an emission spectrum in which there is no wavelength region where the light intensity becomes zero in the wavelength region of at least 450 to 650 nm, preferably in the visible light region. The visible light region is, for example, a wavelength region of 400 to 760 nm, and may be 360 to 760 nm, 400 to 830 nm, or 360 to 830 nm.

  As a white light source having a continuous and broad emission spectrum, for example, a white light emitting diode (white LED) can be exemplified. White LEDs include phosphor-type LEDs (that is, elements that emit white light by combining a light emitting diode that emits blue light or ultraviolet light using a compound semiconductor and a phosphor) and organic light emitting diodes (Organic light-emitting diodes). : OLED). A white light-emitting element that combines a blue light-emitting diode using a compound semiconductor with a yttrium, aluminum, and garnet-based yellow phosphor from the viewpoint of having a continuous and broad emission spectrum and excellent luminous efficiency. Light emitting diodes are preferred.

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. In addition, various measurement evaluation in an Example was performed with the following method.
(1) Total light transmittance Based on JIS-K7105, the total light transmittance was measured using NDH-1001DP by Nippon Denshoku Industries Co., Ltd.

(2) Surface resistance value Based on JIS-K7194, it measured by the 4-terminal method. As a measuring machine, Lotest AMCP-T400 manufactured by Mitsubishi Yuka Co., Ltd. was used.

(3) Crystal grain size A film sample piece laminated with a transparent conductive thin film layer was cut into a size of 1 mm × 10 mm, and attached to the upper surface of an appropriate resin block with the conductive thin film surface facing outward. After trimming this, an ultrathin section approximately parallel to the film surface was prepared by a general ultramicrotome technique.
This section was observed with a transmission electron microscope (JEOL, JEM-2010), a conductive thin film surface portion having no significant damage was selected, and a photograph was taken at an acceleration voltage of 200 kV and a direct magnification of 40000 times.
In the crystal grains observed under a transmission electron microscope, the longest part of all the crystal grains is measured, and the average value of these measured values is defined as the crystal grain diameter. Here, the example regarding the longest part of a crystal grain is shown in FIGS.

(4) Ratio of amorphous part to crystalline part It was calculated from the area ratio of the crystalline part and the amorphous part when observed under a transmission electron microscope.

(5) Thickness (film thickness) of transparent conductive film
A film sample piece laminated with a transparent conductive thin film layer was cut into a size of 1 mm × 10 mm and embedded in an epoxy resin for an electron microscope. This was fixed to a sample holder of an ultramicrotome, and a cross-sectional thin section parallel to the short side of the embedded sample piece was produced. Next, in a section where the thin film of this section is not significantly damaged, a transmission electron microscope (manufactured by JEOL, JEM-2010) is used to obtain a photograph at an acceleration voltage of 200 kV and a bright field at an observation magnification of 10,000 times. The film thickness was determined from the photograph taken.

(6) Pen sliding durability test A transparent conductive film is used as one panel plate, and the other panel plate is an indium-tin composite oxide thin film (containing tin oxide) having a thickness of 20 nm by plasma CVD on a glass substrate. A transparent conductive thin film (Nippon Soda Co., Ltd., S500) comprising 10% by mass) 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. Next, a 5.0 N load was applied to a polyacetal pen (tip shape: 0.8 mmR), and a linear sliding test was performed 300,000 times (150,000 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, 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. The ON resistance is desirably 10 kΩ or less.

(7) Evaluation of rainbow spots An image display device provided with a transparent conductive film having the following constitution was produced according to a conventional method. The change in the visibility of the image was observed by wearing polarized sunglasses (polarizing film) and tilting the neck left and right.

<Evaluation criteria>
○: No rainbow spots were observed, and the visibility was good.
X: Iridescence occurred and visibility was poor.

<Configuration of image display device>
・ Backlight light source: White LED
-Image display cell: Liquid crystal cell-Polarizing plate: A polarizing plate using a TAC film as a polarizer protective film for a polarizer composed of PVA and iodine.
Touch panel: a transparent conductive film (viewing side) formed with a transparent conductive thin film obtained later, and a transparent conductive glass (light source side) formed with a transparent conductive thin film on a glass substrate, spacer A resistive film type touch panel having a structure arranged through a touch panel. In addition, it arrange | positioned so that the angle | corner which the orientation principal axis of a transparent plastic film and the polarization axis of a visual recognition side polarizer form may become 45 degree | times.

(8) Evaluation of retardation Retardation (Re) was measured as follows. That is, using two polarizing plates, the orientation principal axis direction of the film was obtained, and a 4 cm × 2 cm rectangle was cut out so that the orientation principal axis directions were orthogonal to each other, and used as a measurement sample. For this sample, the biaxial refractive index (Nx, Ny) perpendicular to each other and the refractive index (Nz) in the thickness direction were determined by an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.). The absolute value of the difference (| Nx−Ny |) was determined as the anisotropy (ΔNxy) of the refractive index. The thickness d (nm) of the film was measured using an electric micrometer (manufactured by Fine Reef, Millitron 1245D), and the unit was converted to nm. Retardation (Re) was determined from the product (ΔNxy × d) of refractive index anisotropy (ΔNxy) and film thickness d (nm).

  Further, Nx, Ny, Nz and film thickness d (nm) are obtained by the same method as the measurement of retardation, and the average value of (ΔNxz × d) and (ΔNyz × d) is calculated to obtain a thickness direction retardation ( Rth) was determined.

(Production Example 1-transparent plastic film 1)
PET resin pellets having an intrinsic viscosity of 0.62 dl / g were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours, then supplied to an extruder and dissolved at 285 ° C. This polymer is filtered with a filter material of stainless sintered body (nominal filtration accuracy 10 μm particles 95% cut), extruded into a sheet form from the die, and then applied to a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method. It was wound and solidified by cooling to make an unstretched film.

Next, after applying the following adhesive modification coating solution on both sides of the unstretched PET film by a reverse roll method so that the coating amount after drying was 0.08 g / m ² , the coating was dried at 80 ° C. for 20 seconds. .

  The unstretched film on which this coating layer was formed was guided to a tenter stretching machine, and the film was guided to a hot air zone at a temperature of 125 ° C. while being gripped by a clip, and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, the film was processed at a temperature of 225 ° C. for 30 seconds, and further subjected to a relaxation treatment of 3% in the width direction to obtain a uniaxially oriented transparent plastic film 1 having a film thickness of about 100 μm. Obtained. The retardation value was 10200 nm. Rth was 13233 nm and Re / Rth ratio was 0.771.

(Preparation of adhesive modification coating solution)
A transesterification reaction and a polycondensation reaction are carried out by a conventional method, and as a dicarboxylic acid component (based on the whole dicarboxylic acid component) 46 mol% terephthalic acid, 46 mol% isophthalic acid and 8 mol% sodium 5-sulfonatoisophthalate, A water-dispersible sulfonic acid metal base-containing copolymer polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol as a glycol component (based on the entire glycol component) was prepared. Next, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cellosolve, 0.06 parts by mass of nonionic surfactant were mixed and then heated and stirred. After adding 5 parts by mass of a water-dispersible sulfonic acid metal base-containing copolymer polyester resin and continuing to stir until the resin is no longer agglomerated, the resin water dispersion is cooled to room temperature to obtain a solid content concentration of 5.0% by mass. A uniform water-dispersible copolymerized polyester resin liquid was obtained. Furthermore, after dispersing 3 parts by mass of aggregated silica particles (Silicia 310, manufactured by Fuji Silysia Co., Ltd.) in 50 parts by mass of water, 99.46 parts by mass of the water-dispersible copolyester resin liquid was mixed with 0.54 parts by mass of the aqueous dispersion was added, and 20 parts by mass of water was added with stirring to obtain an adhesive modified coating solution.
(Production Example 2-transparent plastic film 2)
PET resin pellets having an intrinsic viscosity of 0.62 dl / g were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours, then supplied to an extruder and dissolved at 285 ° C. This polymer is filtered with a filter material of stainless sintered body (nominal filtration accuracy 10 μm particles 95% cut), extruded into a sheet form from the die, and then applied to a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method. It was wound and solidified by cooling to make an unstretched film.

  The unstretched film was heated to 100 ° C. with a heated roll group and an infrared heater, and then stretched 3.6 times in the longitudinal direction with a roll group having a peripheral speed difference to obtain a uniaxially oriented polyethylene terephthalate film.

Next, the adhesive modified coating solution was applied on both sides of the uniaxially oriented polyethylene terephthalate film by a reverse roll method so that the coating amount after drying was 0.08 g / m ^2, and then dried at 80 ° C. for 20 seconds. did.

The uniaxially stretched film was guided to a tenter stretching machine, and the end of the film was held by a clip while being guided to a hot air zone at a temperature of 125 ° C. and stretched 3.8 times in the width direction. Next, while maintaining the width stretched in the width direction, the film was treated at a temperature of 225 ° C. for 30 seconds, and further subjected to a relaxation treatment of 3% in the width direction to obtain a polyethylene terephthalate film having a film thickness of about 100 μm ) The retardation value was 2250 nm.

The transparent plastic film substrate used in the transparent conductive films 1 to 15 and 17 to 32 is the transparent plastic film 1 having easy-adhesion layers on both sides. As a curable resin layer, 100 parts by mass of a photopolymerization initiator-containing acrylic resin (Daiichi Seika Kogyo Co., Ltd., Seika Beam EXF-01J) and a copolymerized polyester resin (Toyobo Co., Ltd., Byron 200, weight average molecular weight 18, 000) 3 parts by mass, and a solvent mixture of toluene / MEK (8/2: mass ratio) as a solvent is added so that the solid content concentration is 50% by mass and stirred to dissolve uniformly. This coating solution was prepared (hereinafter referred to as coating solution A). The prepared coating solution was applied 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 ray irradiation device (UB042-5AM-W type, manufactured by Eye Graphics Co., Ltd.). .

(Transparent conductive film 1-14)
As a method for obtaining a transparent conductive film, the above method [1] is adopted. The transparent conductive films 1-14 were implemented as follows under the conditions shown in Table 1.
The film was put into a vacuum chamber and evacuated. The longer the evacuation time, the lower the water pressure during film formation during sputtering. Therefore, the ratio of the water pressure to the inert gas in the film formation atmosphere during sputtering was controlled by changing the evacuation time.
After introducing oxygen, argon was introduced as an inert gas to bring the total pressure to 0.5 Pa.
Electric power was applied at a power density of 1 W / cm ^{2 to} an indium oxide sintered target containing tin oxide or an indium oxide sintered target not containing tin oxide, and a transparent conductive film was formed by DC magnetron sputtering. The film thickness was controlled by changing the speed at which the film passed over the target. In addition, the ratio of the moisture pressure to the inert gas in the film formation atmosphere during sputtering was measured using a gas analyzer (manufactured by Inficon, Transpector XPR3).
The film on which the transparent conductive film was formed was heat-treated and then subjected to the measurements shown in Table 1 (however, some were measured without heat treatment). The measurement results are shown in Table 1.

(Transparent conductive film 15)
After the ultimate vacuum was set to 5.0 × 10 ⁻⁴ Pa, oxygen was introduced to 4.0 × 10 ⁻² Pa, and then argon was introduced as an inert gas to bring the total pressure to 0.15 Pa. A transparent conductive film was formed by an ion plating method. The film formation conditions were as follows. Indium oxide containing 5% by mass of tin oxide was used as a deposition material, arc discharge was performed at a discharge voltage of 80 V, a Hearth potential of +40 V, and a discharge current of 120 A, and a transparent conductive film was formed to a thickness of 20 nm. This transparent conductive film was heat-treated at 150 ° C. for 1 hour under atmospheric pressure. The surface resistance after the heat treatment was 410Ω / □, and the total light transmittance was 89%. When observed with a transmission electron microscope, the crystal grain size was 500 nm, and the ratio of the amorphous part to the crystalline part was 0.33. The pen sliding part was transparent and the ON resistance was 0.4 kΩ. Moreover, when the said rainbow-like evaluation was performed using this transparent conductive film, the erythema was not observed but the visibility was favorable.

(Transparent conductive film 16)
A coating solution prepared so that the coating solution A contains 15% by mass of fine particles of indium oxide containing 5% by mass of tin oxide and having a particle size of 30 nm and the thickness of the coating film on the transparent plastic film 1 is 5 μm. It applied using a Meyer bar. After drying at 80 ° C. for 1 minute, UV irradiation (light quantity: 300 mJ / cm ² ) is applied using an UV irradiation device (UB042-5AM-W, manufactured by Eye Graphics Co., Ltd.) to cure and cure the coating film. A mold resin layer was formed. The film having the curable resin layer is put into a vacuum chamber and the ultimate vacuum is 5.0 × 10 ⁻⁴ Pa, then oxygen is introduced to 5.0 × 10 ⁻³ Pa, and then argon is used as an inert gas. The total pressure was 0.5 Pa. Electric power was applied at a power density of 1 W / cm ^{2 to} an indium oxide sintered target containing 5% by mass of tin oxide, and a 20 nm thick transparent conductive film was formed on the coating layer side by a DC magnetron sputtering method. This transparent conductive film was heat-treated at 150 ° C. for 1 hour under atmospheric pressure. The surface resistance after the heat treatment was 200Ω / □, and the total light transmittance was 89%. When observed with a transmission electron microscope, the crystal grain size was 150 nm, and the ratio of the amorphous part to the crystalline part was 0.35. The pen sliding part was transparent and the ON resistance was 0.4 kΩ. Moreover, when the said rainbow-like evaluation was performed using this transparent conductive film, the erythema was not observed but the visibility was favorable.

(Transparent conductive film 17-32)
A transparent conductive film was prepared and evaluated in the same manner as the transparent conductive film 1 under the conditions described in Table 1. The results are shown in Table 1.
(Transparent conductive film 33)
The prepared coating solution was applied to the transparent plastic film 1 using a Mayer bar so that the coating solution A had a thickness of 5 μm. After drying at 80 ° C. for 1 minute, UV irradiation (light quantity: 300 mJ / cm ² ) is applied using an UV irradiation device (UB042-5AM-W, manufactured by Eye Graphics Co., Ltd.) to cure and cure the coating film. A mold resin layer was formed. The film having the curable resin layer is put into a vacuum chamber and the ultimate vacuum is 5.0 × 10 ⁻⁴ Pa, then oxygen is introduced to 5.0 × 10 ⁻³ Pa, and then argon is used as an inert gas. The total pressure was 0.5 Pa. Electric power was applied at a power density of 1 W / cm ^{2 to} an indium oxide sintered target containing 5% by mass of tin oxide, and a 20 nm thick transparent conductive film was formed on the coating layer side by a DC magnetron sputtering method. This transparent conductive film was heat-treated at 150 ° C. for 1 hour under atmospheric pressure. The surface resistance after the heat treatment was 205Ω / □, and the total light transmittance was 88%. When observed with a transmission electron microscope, the crystal grain size was 100 nm, and the ratio of the amorphous part to the crystalline part was 1.5. The pen sliding portion was whitened, and the ON resistance was 900 kΩ. Moreover, when the said rainbow-like evaluation was performed using this transparent conductive film, the erythema was not observed but the visibility was favorable.

(Transparent conductive film 34)
A coating solution prepared so that the coating solution A contains 15% by mass of particles having a particle size of 600 nm composed of indium oxide containing 5% by mass of tin oxide and the transparent plastic film 1 has a coating thickness of 5 μm. It applied using a Meyer bar. After drying at 80 ° C. for 1 minute, UV irradiation (light quantity: 300 mJ / cm ² ) is applied using an UV irradiation device (UB042-5AM-W, manufactured by Eye Graphics Co., Ltd.) to cure and cure the coating film. A mold resin layer was formed. The film having the curable resin layer is put into a vacuum chamber and the ultimate vacuum is 5.0 × 10 ⁻⁴ Pa, then oxygen is introduced to 5.0 × 10 ⁻³ Pa, and then argon is used as an inert gas. The total pressure was 0.5 Pa. Electric power was applied at a power density of 1 W / cm ^{2 to} an indium oxide sintered target containing 5% by mass of tin oxide, and a 20 nm thick transparent conductive film was formed on the coating layer side by a DC magnetron sputtering method. This transparent conductive film was heat-treated at 150 ° C. for 1 hour under atmospheric pressure. The surface resistance after the heat treatment was 195Ω / □, and the total light transmittance was 89%. When observed with a transmission electron microscope, the crystal grain size was 1200 nm, and the ratio of the amorphous part to the crystalline part was 0.25. The pen sliding portion was whitened, and the ON resistance was 900 kΩ. Moreover, when the said rainbow-like evaluation was performed using this transparent conductive film, the erythema was not observed but the visibility was favorable.

(Transparent conductive film 35)
A transparent conductive laminated film was produced in the same manner as the transparent conductive film 1 except that the transparent plastic film 1 was replaced with the transparent plastic film 2. Moreover, when the said rainbow-like evaluation was performed using this transparent conductive film, the erythema produced and it was inferior in visibility. The surface resistance was 260Ω / □, and the total light transmittance was 88%. When observed with a transmission electron microscope, the crystal grain size was 100 nm, and the ratio of the amorphous part to the crystalline part was 0.05. The pen sliding part was transparent and the ON resistance was 0.3 kΩ.

Since the transparent conductive films 1-34 use the polyester film with high retardation, the iridescence was not observed but the visibility was favorable. On the other hand, since the transparent conductive film 35 uses a film having a retardation of less than 3000 nm, rainbow spots were observed and visibility was poor.
The transparent conductive films 1 to 16 were transparent in the sliding portion even after the pen sliding durability test, the ON resistance was 10 kΩ or less, and very excellent pen sliding durability was obtained.
The transparent conductive films 20, 23, 25, 27, 28, and 29 were excellent in pen sliding durability test, but were inferior in other characteristics. The transparent conductive films 20, 23, 28, and 29 resulted in higher surface resistance values than practical levels. The transparent conductive film 25 has a lower total light transmittance than a practical level. In Table 1, the evacuation time was 2 to 7 hours for the transparent conductive films 1 to 14, 17 to 26, and 28 to 32, but it took 24 hours for the transparent conductive film 27, and the evacuation time was extremely high. It was long.

ADVANTAGE OF THE INVENTION According to this invention, the fall of the image quality represented by the rainbow when it visually recognizes through a polarizing filter is reduced, and the visibility of layer display apparatuses, such as a liquid crystal display, is improved. Moreover, according to a preferable aspect, a transparent conductive film having very excellent pen sliding durability is obtained, which is extremely useful for applications such as a touch panel for pen input.

Claims (5)

  A transparent conductive film having a transparent conductive film laminated on at least one surface on a transparent plastic film substrate, wherein the retardation of the transparent plastic film substrate is 3000 nm to 30000 nm. The transparent conductive film is made of indium oxide, the crystal grain size of the indium oxide is 30 to 1000 nm, and the ratio of the amorphous part to the crystalline part of the transparent conductive film is 0.00 to 0.50. The transparent conductive film according to claim 1.   The transparent conductive film according to claim 2, wherein the transparent conductive film further contains 0.5 to 8 mass% of tin oxide.   The transparent conductive film according to claim 1, wherein the transparent conductive film has a thickness of 10 to 100 nm.   A resistive touch panel using the transparent conductive film according to claim 1.