KR20200070240A - Transparent conductive film and method for manufacturing the same - Google Patents

Abstract

The transparent conductive film 1 is provided with a transparent substrate 2 and a transparent conductive layer 6 in order. The transparent substrate 2 contains a resin having a glass transition temperature of 130°C or higher. The transparent conductive layer 6 is amorphous. The difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction in the transparent conductive film 1 after heating at 150° C. for 90 minutes is 0.05% or less.

Description

Transparent conductive film and method for manufacturing the same

The present invention relates to a transparent conductive film and its manufacturing method.

It is known that a transparent conductive film is provided with a transparent resin film and a transparent conductive film in order.

For example, a method of obtaining a transparent conductive film in which an amorphous transparent conductive film is formed on a transparent resin film and heating it to crystallize the transparent conductive film has been proposed (for example, see Patent Document 1).

In Patent Document 1, it is proposed to anneal the transparent resin film at 150°C for 3 minutes in advance in order to suppress the occurrence of curl (winding or warping) in the transparent resin film during the aforementioned heating of the amorphous transparent conductive film. (For example, see Patent Document 1).

In Patent Document 1, an amorphous transparent conductive film is formed on an annealed transparent resin film to produce a transparent conductive film, and curling when heated at 130° C. for 90 minutes is suppressed in the transparent conductive film.

Japanese Patent Publication No. 2016-124106

Recently, heat resistance at a higher temperature (more severe conditions) is required for the transparent conductive film. The transparent conductive film described in Patent Literature 1 has a problem that the above-mentioned requirements cannot be satisfied.

On the other hand, when the transparent conductive film is heated immediately after being produced (just after the transparent conductive film is formed on the surface of the transparent resin film), the transparent resin film is stretched by heating, and the relatively flexible amorphous transparent conductive film is stretched to the stretch of the transparent resin film. To follow. Then, the transparent conductive film is crystallized on the basis of heating.

However, usually, after the transparent conductive film is produced (after the transparent conductive film is formed on the surface of the transparent resin film), a predetermined period (time) inevitably exists until crystallization of the transparent conductive film. Therefore, a part of the amorphous transparent conductive film is crystallized (so-called natural crystallization) in the above period, and as a result, the transparent conductive film becomes harder than the transparent conductive film immediately after production.

Thereafter, when the transparent conductive film is to be crystallized by heating, the transparent conductive film cannot follow the elongation due to heating of the transparent resin film due to the hardness based on the partially crystallized portion, and as a result, the transparent conductive completely crystallized There is a problem that cracks (cracks) are generated in the film.

The present invention provides a transparent conductive film which is excellent in heat resistance and capable of suppressing damage to the transparent conductive layer even when a period until crystallization is present.

The present invention (1) is provided with a transparent substrate and a transparent conductive layer in order, the transparent substrate contains a resin having a glass transition temperature of 130° C. or higher, and the transparent conductive layer is amorphous, and is 90 at 150° C. After heating for a minute, the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction includes a transparent conductive film having 0.05% or less.

The present invention (2) includes the transparent conductive film according to (1), wherein the resin has a linear expansion coefficient of 5.5×10 ⁻⁵ /°C or higher and 8.0×10 ^-5 /°C or lower.

The present invention (3) includes the transparent conductive film according to (1) or (2), wherein the resin is at least one member selected from the group consisting of cycloolefin-based resins and polycarbonate resins.

In this invention (4), the said transparent conductive layer contains the transparent conductive film in any one of (1)-(3) containing an indium tin composite oxide.

The present invention (5) includes the transparent conductive film according to any one of (1) to (4), which has a thickness of 20 µm or more and 100 µm or less.

The present invention (6) further comprises an anti-blocking layer, a hard coat layer and an optical adjustment layer, in which the anti-blocking layer, the transparent substrate, the hard coat layer, the optical adjustment layer and the transparent conductive layer are in order. The transparent electroconductive film in any one of (1)-(5) arrange|positioned is included.

In the present invention (7), a first step of preparing a transparent substrate, a second step of annealing the transparent substrate, and an amorphous transparent conductive layer are disposed on the transparent substrate, and the transparent substrate and the transparent conductive layer are sequentially ordered. A third step of manufacturing a transparent conductive film provided as it is, and in the second step, the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction after heating the transparent conductive film at 150° C. for 90 minutes. And a method for producing a transparent conductive film, which anneals the transparent substrate so as to be 0.05% or less.

In the second step, the present invention (8) includes a method for producing the transparent conductive film according to (7), wherein the transparent substrate is heated at less than 145° C. for 1 minute or more and 5 minutes or less.

In the transparent conductive film of the present invention produced by the method for producing the transparent conductive film of the present invention, the transparent base material contains a resin having a glass transition temperature of 130°C or higher, and thus excellent heat resistance.

In addition, since the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction after heating the transparent conductive film at 150° C. for 90 minutes is 0.05% or less, even if a period until crystallization exists, damage to the transparent conductive layer is prevented. Can be suppressed.

1A to 1D are process cross-sectional views showing a manufacturing method of an embodiment of the transparent conductive film of the present invention, in which FIG. 1A is a first step of preparing a substrate laminate, and a second step of annealing the substrate laminate , FIG. 1B shows a third step of arranging the amorphous transparent conductive layer, FIG. 1C shows a state in which a part of the transparent conductive layer is crystallized with time, and FIG. 1D shows a step of crystallizing the transparent conductive layer. .
2A to 2D are process cross-sectional views showing a modification of the manufacturing method shown in FIGS. 1A to 1D (a transparent conductive film without a hard coat layer, an optical adjustment layer and an anti-blocking layer), and FIG. 2A is transparent The first step of preparing the substrate, and the second step of annealing the transparent substrate, FIG. 2B, a third process of arranging the amorphous transparent conductive layer, FIG. 2C, a part of the transparent conductive layer due to change over time 2D shows the process of crystallizing the transparent conductive layer.

<one embodiment>

An embodiment of the transparent conductive film of the present invention will be described below with reference to Figs. 1A to 1D. 1A to 1D, the vertical direction of the paper surface is the vertical direction (thickness direction, the first direction), the upper paper surface is the upper side (one side of the thickness direction, the first direction one side), and the lower paper surface is the lower side (thickness) Direction other side, first direction other side). In addition, the left and right directions of the paper and the depth direction are surface directions perpendicular to the vertical direction. Specifically, it conforms to the direction arrows in each drawing. By the definition of this direction, there is no intention to limit the direction at the time of manufacture and use of the substrate laminate 7, the transparent conductive film 1 and the crystallized transparent conductive film 10, which will be described later.

As shown in Fig. 1B, the transparent conductive film 1 has a film shape having a predetermined thickness, extends in the plane direction, and has a flat upper surface and a flat lower surface. The transparent conductive film 1 is a part of, for example, a base material for a touch panel provided in an image display device, that is, it is not an image display device. That is, the transparent conductive film 1 is a component for manufacturing an image display device or the like, and does not include an image display element such as an LCD module, and is a component that is distributed alone and is an industrially available device.

For the transparent conductive film 1, for example, the anti-blocking layer 4, the transparent substrate 2, the hard coat layer 3, the optical adjustment layer 5, and the transparent conductive layer 6 are ordered upwards. As it is. Preferably, the transparent conductive film 1 consists of only the anti-blocking layer 4, the transparent substrate 2, the hard coat layer 3, the optical adjustment layer 5, and the transparent conductive layer 6. Moreover, the anti-blocking layer 4, the transparent base material 2, the hard coat layer 3, and the optical adjustment layer 5 are provided in the base material laminated body 7 mentioned later.

The transparent substrate 2 is a transparent substrate for ensuring the mechanical strength of the transparent conductive film 1. Moreover, the transparent base material 2 supports the transparent conductive layer 6 together with the hard coat layer 3 and the optical adjustment layer 5.

The transparent substrate 2 has a film shape, extends in the plane direction, and has a flat upper surface and a flat lower surface.

The material of the transparent base material 2 includes a resin having flexibility, and more specifically, a resin (high glass transition temperature resin) that satisfies the glass transition temperature to be described later. The resin is selected from, for example, cycloolefin resins, polycarbonate resins, polyethersulfone resins, polyimide resins, polyarylate resins, polyphenylene sulfide resins, and the like. The resin can be used alone or in combination of two or more.

As the resin, from the viewpoint of securing excellent heat resistance, preferably, a cycloolefin-based resin or a polycarbonate-based resin is selected, and more preferably a cycloolefin-based resin is selected from a viewpoint of ensuring low birefringence.

The cycloolefin-based resin is not particularly limited as long as it is a resin having a unit of a monomer composed of a cyclic olefin (cycloolefin). Examples of the cycloolefin-based resin include cycloolefin polymer (COP) and cycloolefin copolymer (COC). Cycloolefin polymer is a polymer of cyclic olefin. The cycloolefin copolymer is a copolymer of a cyclic olefin and an olefin such as ethylene.

Cyclic olefins include, for example, polycyclic cyclic olefins and monocyclic cyclic olefins. As the polycyclic cyclic olefin, for example, norbornene, methylnorbornene, dimethylnorbornene, ethylnorbornene, ethylidenenorbornene, butylnorbornene, dicyclopentadiene, dihydro Dicyclic pentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, and other bicyclic dienes, such as tricyclopentadiene tricyclic diene, such as tetracyclopentadiene, tetracyclodode And four cyclic dienes such as sen, methyltetracyclododecene, and dimethylcyclotetradodecene. As a monocyclic cyclic olefin, cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctatriene, cyclododecatriene, etc. are mentioned, for example.

As a cycloolefin type resin, COP is mentioned preferably from a viewpoint of reducing birefringence.

Examples of the polycarbonate-based resin include aliphatic polycarbonate, aromatic polycarbonate, and aliphatic-aromatic polycarbonate. Specifically, as the polycarbonate-based resin, for example, polycarbonate (PC) using bisphenols such as bisphenol A polycarbonate, branched bisphenol A polycarbonate, and further expanded polycarbonate, copolycarbonate, block copolycarbonate , Polyester carbonate, polyphosphonate carbonate, diethylene glycol bisallyl carbonate (CR-39), and the like. Polycarbonate resins include, for example, blends with other components such as bisphenol A polycarbonate blends, polyester blends, ABS blends, polyolefin blends, and styrene-maleic anhydride copolymer blends.

The glass transition temperature of the resin is 130°C or higher, preferably 135°C or higher, preferably 140°C or higher, and for example, 175°C or lower, preferably 160°C or lower. When the glass transition temperature of the resin is less than the above-mentioned lower limit, the heat resistance of the transparent substrate 2 is lowered. In other words, when the glass transition temperature of the resin exceeds the above-mentioned lower limit, the transparent base material 2 is excellent in heat resistance.

On the other hand, if the glass transition temperature of the resin is less than the above upper limit, the moldability at the time of manufacturing the transparent base material 2 (specifically, during extrusion molding) is excellent. The glass transition temperature is determined by differential scanning calorimetry (DSC) described in JIS K 7121 (1987).

The linear expansion coefficient of the resin is, for example, 2.0 × 10 ^-5 / ℃ or more, and further 4.0 × 10 ^-5 / ℃ or more, and further 5.0 × 10 ^-5 / ℃ or more, and further 5.5 × 10 ^{- 5} /℃ or higher. When the linear expansion coefficient of the resin is equal to or greater than the above-mentioned lower limit, in the fourth step (the step of crystallizing the transparent conductive layer 6, which will be described later), the transparent base material 2 is excessively stretched, so that the transparent conductive layer 6 ) It becomes difficult to follow the elongation of the transparent substrate 2, and thus tends to cause damage (task) of the transparent conductive layer 6. However, although this transparent conductive film 1 will be described later, the above-described problem is solved because the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction is 0.05% or less.

Further, the coefficient of linear expansion of the resin is, for example, 20 × 10 ^-5 /°C or less, preferably 15 × 10 ^-5 /°C or less, more preferably 10 × 10 ^-5 /°C or less, and more preferably Is 8.0 x 10 ^-5 /°C or less. When the linear expansion coefficient of the resin is equal to or less than the above-described upper limit, excessive stretching of the transparent substrate 2 is suppressed in the fourth step (the step of crystallizing the transparent conductive layer 6, which will be described later), and therefore the transparent conductive layer (6) The elongation of this transparent base material 2 can be reliably followed, thereby preventing damage to the transparent conductive layer 6.

The coefficient of linear expansion of the resin is determined by a linear expansion measuring device based on ASTM E831.

The hard coat layer 3 is a scratch protective layer for preventing the scratch from being easily generated on the transparent conductive film 1. The hard coat layer 3 has a film shape, and is disposed, for example, on the entire upper surface of the transparent substrate 2 so as to contact the upper surface of the transparent substrate 2. The material of the hard coat layer 3 is, for example, a hard coat composition. As a hard coat composition, the mixture etc. of Unexamined-Japanese-Patent No. 2016-179686 etc. are mentioned, for example. The mixture contains, for example, resins (binder resins) such as acrylic resins and urethane resins. The thickness of the hard coat layer 3 is, for example, 0.1 μm or more, preferably 0.5 μm or more, and for example, 10 μm or less, preferably 5 μm or less.

The optical adjustment layer 5 has the optical properties of the transparent conductive film 1 in order to ensure excellent transparency to the transparent conductive film 1 while suppressing the visibility of the transparent electrode pattern in the transparent conductive layer 6 ( For example, it is a layer that adjusts the refractive index). The optical adjustment layer 5 has a film shape, and is disposed so as to contact the upper surface of the hard coat layer 3 on the entire front surface of the hard coat layer 3, for example. More specifically, the optical adjustment layer 5 is disposed between the hard coat layer 3 and the transparent conductive layer 6 so as to contact the upper surface of the hard coat layer 3 and the lower surface of the transparent conductive layer 6. It is. The material of the optical adjustment layer 5 is, for example, an optical adjustment composition. As an optical adjustment composition, the mixture etc. which were described in Unexamined-Japanese-Patent No. 2016-179686 etc. are mentioned, for example. The mixture contains, for example, a resin (binder resin) such as an acrylic resin, and inorganic or organic particles (preferably inorganic particles such as zirconia). The thickness of the optical adjustment layer 5 is, for example, 50 nm or more, preferably 100 nm or more, and for example, 800 nm or less, preferably 300 nm or less.

The anti-blocking layer 4 imparts blocking resistance to the surfaces of the plurality of transparent conductive films 1 that are in contact with each other, such as when a plurality of the transparent conductive films 1 are laminated in the thickness direction. The anti-blocking layer 4 forms the lowest surface in the transparent conductive film 1. Specifically, the anti-blocking layer 4 is arranged to contact the lower surface of the transparent substrate 2 on the entire lower surface of the transparent substrate 2. The material of the anti-blocking layer 4 is, for example, an anti-blocking composition. As an anti-blocking composition, the mixture etc. of Unexamined-Japanese-Patent No. 2016-179686 etc. are mentioned, for example. The mixture contains, for example, a resin such as an acrylic resin (binder resin), and inorganic or organic particles (preferably organic particles such as styrene). The thickness of the anti-blocking layer 4 is, for example, 0.1 μm or more, preferably 0.5 μm or more, and for example, 10 μm or less, preferably 5 μm or less.

The transparent conductive layer 6 is amorphous. When the transparent conductive layer 6 is amorphous, it is immersed in hydrochloric acid (concentration 5 mass%) at 20 DEG C for 15 minutes, washed with water and dried, and identified as having a resistance between terminals of about 15 mm greater than 10 kΩ (definition) ) do.

The transparent conductive layer 6 is a transparent conductive layer before complete crystallization in order to become a crystallized transparent conductive layer 6C (described later) in the fourth step (described later, heating step, see FIG. 1D ). The transparent conductive layer 6 is included in the "transparent conductive layer" of the present invention, and the amorphous transparent conductive layer 6A immediately after production shown in Fig. 1B (to be described later) and the amorphous transparent conductive layer shown in Fig. 1C ( Both of the partially crystallized transparent conductive layer 6B (to be described later) after a predetermined period has elapsed immediately after the production of 6A).

In addition, the transparent conductive layer 6 is finally formed by a transparent electrode pattern by etching.

The transparent conductive layer 6 is a top layer of the transparent conductive film 1, has a film shape, and is disposed on the entire front surface of the optical adjustment layer 5 so as to contact the upper surface of the optical adjustment layer 5.

The material of the transparent conductive layer 6 is, for example, an indium-containing oxide such as indium-tin composite oxide (ITO), for example, an antimony-containing oxide such as antimony-tin composite oxide (ATO), and the like. , Preferably indium-containing oxide, More preferably, ITO is mentioned. When the material of the transparent conductive layer 6 is ITO, the transparent conductive layer 6 can achieve both excellent transparency and excellent conductivity.

When ITO is used as the material of the transparent conductive layer 6, the tin oxide (SnO ₂ ) content is, for example, 0.5% by mass or more with respect to the total amount of tin oxide and indium oxide (In ₂ O ₃ ). It is 3 mass% or more, and is 15 mass% or less, for example, Preferably it is 13 mass% or less.

"ITO" may be a complex oxide containing at least indium (In) and tin (Sn), and may contain additional components other than these. Examples of the additional component include metal elements other than In and Sn, and specifically, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, and W , Fe, Pb, Ni, Nb, Cr, Ga, and the like.

The thickness of the transparent conductive layer 6 is, for example, 10 nm or more, preferably 20 nm or more, and for example, 100 nm or less, preferably 35 nm or less.

The surface resistance of the transparent conductive layer 6 is, for example, more than 200 Ω/□, more preferably 250 Ω/□ or more, and, for example, 500 Ω/□ or less, and more preferably 400 Ω/□ or less. .

Next, the manufacturing method of the transparent conductive film 1 and crystallization of the transparent conductive layer 6 of the transparent conductive film 1 obtained by it are demonstrated.

The manufacturing method of the transparent conductive film 1 includes the first process of preparing the substrate laminate 7 (see FIG. 1A ), the second process of annealing the substrate laminate 7 (see FIG. 1A ), and transparent conductivity. A third process (see Fig. 1B) of arranging the layer 6 on the substrate laminate 7 is provided. In this manufacturing method, the 1st process, 2nd process, and 3rd process are performed in order.

Moreover, this manufacturing method is implemented by a roll-to-roll system, for example. In other words, the substrate laminate 7 to be prepared and the transparent conductive film 1 to be produced have MD directions (machine direction or conveying direction) and TD directions (orthogonal direction or width direction).

As shown in FIG. 1A, in the first step, a substrate laminate 7 including the transparent substrate 2 is prepared.

Specifically, the substrate laminate 7 includes an anti-blocking layer 4, a transparent substrate 2, a hard coat layer 3, and an optical adjustment layer 5. Preferably, the substrate laminate 7 is composed of only the anti-blocking layer 4, the transparent substrate 2, the hard coat layer 3, and the optical adjustment layer 5. The base layered product 7 has a film shape having a predetermined thickness, extends in the plane direction, and has a flat upper surface and a flat lower surface. Moreover, the base material laminated body 7 has a long shape wound on the roll.

To prepare the substrate laminate 7, for example, first, a transparent substrate 2 having a long shape is prepared.

Next, with respect to the transparent substrate 2, the hard coat layer 3, the anti-blocking layer 4, and the optical adjustment layer 5 are sequentially arranged in a roll-to-roll manner. Specifically, the diluent of the hard coat composition and the diluent of the anti-blocking composition are applied to each of the upper and lower surfaces of the transparent substrate 2, and after drying, each of the hard coat composition and the anti-blocking composition is cured by ultraviolet irradiation. . Thereby, each of the hard coat layer 3 and the anti-blocking layer 4 is formed on each of the upper and lower surfaces of the transparent substrate 2. Thereafter, a diluent of the optical adjustment composition is applied to the upper surface of the hard coat layer 3, and after drying, the optical adjustment composition is cured by ultraviolet irradiation. Thereby, the optical adjustment layer 5 is formed.

As shown in Fig. 1A, in the second step, the substrate laminate 7 is annealed.

For example, in the second step, at least the transparent substrate 2 may be annealed, and specifically, the substrate laminate 7 is heated.

To heat the substrate laminate 7, for example, the substrate laminate 7 is placed in the heating furnace 8. As a heating furnace, a vacuum heating apparatus etc. are mentioned, for example. Specifically, in the roll-to-roll system, the substrate laminate 7 is passed through the heating furnace 8.

As for the heating conditions, after the second step, the transparent conductive layer 6 was heated at 150° C. for 90 minutes (detailed later, after the heat resistance test A in Example 1), the thermal shrinkage in the MD direction and TD It is adjusted so that the difference in the heat shrinkage rate in the direction is 0.05% or less. Specifically, the heating temperature of the heating furnace 8 is, for example, less than 145°C, preferably 140°C or less, more preferably 135°C or less, still more preferably 130°C or less, particularly preferably 120 ℃ or less, most preferably 110 ℃ or less. When the heating temperature is lower than the above-described upper limit, the difference in the heat shrinkage rate described above can be reliably set to 0.05% or less.

Moreover, the heating temperature of the heating furnace 8 is, for example, 70°C or higher, preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 95°C or higher. When the heating temperature exceeds the above-mentioned lower limit, it is possible to control the respective heat shrinkage rates in the MD direction and the TD direction after heating the transparent conductive layer 6 at 150° C. for 90 minutes after the second step.

The heating time is, for example, 0.1 minutes or more, preferably 0.5 minutes or more, and for example, 5 minutes or less, preferably 3 minutes or less. When the heating time is within the above-described range, the difference in the above-described heat shrinkage rate can be reliably set to 0.05% or less.

In addition, when this manufacturing method is implemented in a roll-to-roll system, the heating time is the passage speed of the substrate laminate 7 in the heating furnace 8 and the length in the MD direction of the heating furnace 8 (no Length).

Moreover, when this manufacturing method is implemented by a roll-to-roll system, the tension in the conveyance direction of the base material laminated body 7 in a 2nd process is not specifically limited, For example, 10 N or more, It is preferably 25 N or more, and for example, 300 N or less, preferably 150 N or less, more preferably 100 N or less. When the tension is equal to or more than the above-mentioned lower limit, the substrate laminate 7 can be conveyed with excellent workability. If the tension is equal to or less than the above-described upper limit, the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction, which will be described later, can be reliably set within a desired range.

Next, as shown in FIG. 1B, in the third step, the transparent conductive layer 6 is disposed on the substrate laminate 7.

The transparent conductive layer 6 is formed on the upper surface of the optical adjustment layer 5 by, for example, sputtering. Specifically, in the roll-to-roll system, the annealed substrate stack 7 is passed through a sputtering device (not shown).

Thereby, the transparent conductive layer 6 is formed on the upper surface of the substrate laminate 7 as the amorphous transparent conductive layer 6A. The amorphous transparent conductive layer 6A is a layer immediately after being formed, and is an amorphous layer in which crystallization does not substantially proceed.

Thereby, the transparent conductive film 1 provided with the base material laminated body 7 and the transparent conductive layer 6 (amorphous transparent conductive layer 6A) in order toward the thickness direction upper side is obtained. The transparent conductive film 1 is preferably composed of only the substrate laminate 7 and the transparent conductive film 1.

The thickness of the transparent conductive film 1 is, for example, 10 μm or more, preferably 20 μm or more, and for example, 200 μm or less, preferably 100 μm or less. When the thickness is equal to or less than the above-described upper limit, the thickness of the transparent conductive film 1 can be reduced. When the thickness is more than the above upper limit, the transparent conductive film 1 has excellent handling properties and excellent mechanical strength.

In this transparent conductive film 1, since the surface resistance of the transparent conductive layer 6 is relatively high, it is still difficult to act as a transparent electrode pattern. That is, the transparent conductive layer 6 is not yet a crystallized transparent conductive layer 6C (described later). Therefore, the transparent conductive film 1 is a preparation film for producing a crystallized transparent conductive film 10 (see below, see Fig. 1D) having a crystallized transparent conductive layer 6C, and the crystallized transparent conductive film 10 is no. On the other hand, the transparent conductive film 1 is distributed alone in the film.

After this transparent conductive film 1 (that is, the laminated film comprising the substrate laminate 7 and the transparent conductive layer 6) was heated at 150° C. for 90 minutes (heat resistance test A in the example described below) , The difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction is 0.05% or less, preferably less than 0.05%, more preferably 0.3% or less, still more preferably 0.2% or less, and particularly preferably less than 0.2%.

When the difference between the thermal contraction rate in the MD direction and the thermal contraction rate in the TD direction in the transparent conductive film 1 after heating (heat resistance test A) exceeds the above upper limit, damage to the transparent conductive layer 6 cannot be suppressed.

To find the above-described method for measuring the heat shrinkage rate in each direction and the difference between them, the transparent conductive film 1 before heating is marked with a predetermined interval in each of the TD direction and the TD direction, and the intervals are measured. Then, after that, the transparent conductive film 1 is heated, and the above-described intervals are measured again, and the above-described difference is obtained from the results. Details will be described in the following examples. Moreover, it can also be obtained by a method using a CNC three-dimensional measuring machine as described in Japanese Patent Application Laid-Open No. 2016-124106.

1C and 1D, after that, the transparent conductive film 1 crystallizes the transparent conductive layer 6 of the transparent conductive film 1 after a predetermined period of time, thereby crystallizing the transparent conductive layer ( It becomes the crystallization transparent conductive film 10 provided with 6C).

The above-described period is a time from immediately after production of the transparent conductive film 1 (more specifically, immediately after the amorphous transparent conductive layer 6A is formed) to immediately before crystallizing the transparent conductive layer 6 completely. In the above period, for example, the transparent conductive film 1 is stored (stored) in a warehouse possessed by the manufacturer of the transparent conductive film 1 and/or the crystallized transparent conductive film 10, and furthermore, crystallized transparent conductive The manufacturer of the film 10 is waited until the amorphous transparent conductive layer 6A is passed through a heating device, or the amorphous transparent conductive layer 6A is conveyed.

Specifically, the above-described period is, for example, 10 hours or more, 1 day or more, further 10 days or more, further 100 days or more, and, for example, within 10 years.

The transparent conductive film 1 in the above-described period is stored (for example, atmospheric or conveyed) under an atmospheric atmosphere, an inert gas atmosphere, and the like, and is usually stored under an atmospheric atmosphere.

As shown in Fig. 1C, when the transparent conductive film 1 is stored in the above-described environment for a predetermined period, a part of the amorphous transparent conductive layer 6A is crystallized. That is, crystallization in the amorphous transparent conductive layer 6A partially proceeds (so-called natural crystallization partially occurs). However, the transparent conductive layer 6 is not completely crystallized, and the amorphous transparent conductive layer 6A reaches the partially crystallized transparent conductive layer 6B, but does not reach the crystallized transparent conductive layer 6C.

In addition, this partially crystallized transparent conductive layer 6B is not completely crystallized, and is still included in the "transparent conductive layer" of the "amorphous" of the present invention, since it has an amorphous state.

The conditions under which the amorphous transparent conductive layer 6A is naturally crystallized are conditions when the amorphous transparent conductive layer 6A is stored for the above-described period, and an accelerated test in the heat resistance test C described later (for example, 50°C, 150 hours or more, and 200 hours or less).

On the other hand, if the above period does not exist, that is, if the amorphous transparent conductive layer 6A immediately after being produced is crystallized by heating to form a crystallized transparent conductive layer 6C, the transparent substrate 2 is elongated by heating In addition, the relatively flexible amorphous transparent conductive layer 6A can follow the elongation of the transparent substrate 2.

However, since the above-described period inevitably exists and it is virtually inevitable that the amorphous transparent conductive layer 6A is stored for the above-described period, the amorphous transparent conductive layer 6A inevitably becomes the partially crystallized transparent conductive layer 6B. And, since the partially crystallized transparent conductive layer 6B is harder than the amorphous transparent conductive layer 6A, when the partially crystallized transparent conductive layer 6B is heated in a subsequent fourth step (heating step), the partially crystallized transparent The conductive layer 6B does not sufficiently follow the elongation due to heating of the transparent substrate 2, and therefore, there is a possibility that cracks (cracks) occur in the crystallized transparent conductive layer 6C.

However, since the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction of the transparent conductive film 1 is 0.05% or less, cracks (cracks) described above can be suppressed.

Thereafter, as shown in Fig. 1D, the transparent conductive layer 6 is crystallized. Specifically, the partially crystallized transparent conductive layer 6B is completely crystallized. Thereby, the crystallized transparent conductive layer 6C is formed.

To crystallize the partially crystallized transparent conductive layer 6B, the partially crystallized transparent conductive layer 6B is heated, for example, in an atmosphere. The heating temperature is, for example, 110°C or higher, preferably 120°C or higher, and for example, 150°C or lower, preferably 130°C or lower. Heating time is 15 minutes or more, for example, 120 minutes or less.

Thereby, the crystallized transparent conductive layer 6C is formed. The crystallized transparent conductive layer 6C is crystalline, immersed in hydrochloric acid (concentration 5% by mass) at 20°C for 15 minutes, washed with water and dried, and identified as having a resistance between terminals of about 15 mm to 10 kΩ or less (definition) ) do.

The surface resistance of the crystallized transparent conductive layer 6C is lower than that of the amorphous transparent conductive layer 6A and the partially crystallized transparent conductive layer 6B, specifically, for example, 200 Ω/□ or less, preferably It is 150 Ω/□ or less, and 10 Ω/□ or more, for example.

In the crystallized transparent conductive layer 6C, damage such as cracks is suppressed as described above.

Thereby, the crystallized transparent conductive film 10 which has the base layer laminated body 7 and the crystallized transparent conductive layer 6C (crystallized transparent conductive layer 6) sequentially in the thickness direction upward is obtained. The crystallized transparent conductive film 10 preferably consists of only the base layered product 7 and the crystallized transparent conductive layer 6C.

And the transparent conductive film obtained by the manufacturing method of this transparent conductive film 1, and comprises an amorphous transparent conductive layer 6 (amorphous transparent conductive layer 6A and partially crystallized transparent conductive layer 6B) In 1), since the transparent substrate 2 contains a resin having a glass transition temperature of 130°C or higher, it is excellent in heat resistance.

In addition, the heat shrinkage in the MD direction and the heat shrinkage in the TD direction after heating the transparent conductive film 1 (a laminated film comprising the substrate laminate 7 and the transparent conductive layer 6) at 150°C for 90 minutes. Since the difference is 0.05% or less, even if a period until the transparent conductive layer 6 crystallizes by heating, damage to the crystallized transparent conductive layer 6C can be suppressed.

Specifically, the partially crystallized transparent conductive layer 6B is harder than the amorphous transparent conductive layer 6A as described above, and thus extends to the elongation of the transparent substrate 2 based on heating in the fourth step. This transparent conductive film 1 has a tendency to generate cracks (cracks) in the crystallized transparent conductive layer 6C shown in FIG. 1D because it cannot follow, and this transparent conductive film 1 has a heat shrinkage in the MD direction and a TD direction Since the difference in the heat shrinkage ratio of is 0.05% or less, the balance between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction can be adjusted. Therefore, generation|occurrence|production of a crack (crack) in the crystallized transparent conductive layer 6C in the crystallized transparent conductive film 10 shown in FIG. 1D can be suppressed (prevented).

In addition, the crystallized transparent conductive film 10 including the crystallized transparent conductive layer 6C that is completely crystallized has a crystallized transparent conductive layer 6C, an amorphous transparent conductive layer 6 (amorphous transparent conductive layer 6A), and a part Since it is neither a crystallized transparent conductive layer 6B), it is not included in the "transparent conductive film" of the present invention.

<Modification>

In a modified example, the same reference numerals are assigned to the same members and processes as those in the above-described embodiment, and detailed descriptions thereof are omitted.

Moreover, each modification can exhibit the same effect as that of the above-described embodiment.

In this modified example, as shown in Fig. 2B, the transparent conductive film 1 has a hard coat layer 3 (see Fig. 1B), an anti-blocking layer 4 (see Fig. 1B), and an optical adjustment layer 5. (See FIG. 1B) is not provided. The transparent conductive film 1 comprises a transparent substrate 2 and an amorphous transparent conductive layer 6A (transparent conductive layer 6) in order. The transparent conductive film 1 is preferably composed of only the transparent substrate 2 and the amorphous transparent conductive layer 6A.

In order to obtain the transparent conductive film 1 shown in Fig. 2B, as shown in Fig. 2A, in the first step, the transparent base material 2 is prepared.

Subsequently, in the second step, the transparent substrate 2 is annealed using a heating furnace 8.

Next, as shown in FIG. 2B, in the third step, the amorphous transparent conductive layer 6A is disposed on the transparent substrate 2. Specifically, the amorphous transparent conductive layer 6 is directly formed on the upper surface of the annealed transparent substrate 2.

Thereby, the transparent conductive film 1 provided with the transparent base material 2 and the amorphous transparent conductive layer 6A in order is obtained.

The heat shrinkage in the MD direction and the heat shrinkage in the TD direction after heating the transparent conductive film 1 (that is, a laminated film comprising the transparent substrate 2 and the transparent conductive layer 6) at 150°C for 90 minutes. The difference is 0.05% or less.

Moreover, although not shown, the amorphous transparent conductive layer 6A may be formed on both the upper and lower sides of the transparent substrate 2 in the transparent conductive film 1. The transparent conductive layer 6 may be formed on both the upper and lower sides of the transparent substrate 2 in the transparent conductive film 1.

Example

Examples and comparative examples are shown below, and the present invention will be described in more detail. In addition, this invention is not limited to an Example and a comparative example at all. The specific ratios such as the blending ratio (content ratio), physical property values, and parameters used in the following description are those described in the "Specific Contents for Carrying Out the Invention" above, and the corresponding blending ratio (content ratio). , It can be replaced with the upper limit (value defined as "below", "less than") or lower limit (value defined as "above", "excess") of the description, such as physical property values and parameters. In addition, in each example, part and% are all based on mass.

Example 1

As shown in Fig. 1A, first, a transparent substrate 2 was prepared. Specifically, the transparent base material 2 made of COP (glass transition temperature 145°C, linear expansion coefficient 6-7 x 10 ^-5 /°C, thickness 40 µm, in-plane birefringence 0.0001, manufactured by Nippon Zeon Co., Ltd., "ZEONOR" (Registered trademark)) was prepared as a long substrate wound in a roll shape.

Subsequently, the hard coat layer 3, the anti-blocking layer 4, and the optical adjustment layer 5 were formed in a roll-to-roll manner with respect to the transparent substrate 2 in order.

First, on the upper surface of the transparent film base 2, a diluent of a hard coat composition made of a binder resin (urethane-based polyfunctional polyacrylate, trade name "UNIDIC", manufactured by DIC) is also included, and the transparent film base 2 On the lower surface, a binder resin (urethane-based polyfunctional polyacrylate, trade name "UNIDIC", manufactured by DIC) and particles (cross-linked acrylic/styrene-based resin particle, trade name "SSX105", diameter: 3 µm, manufactured by Sekisui Resin) A diluent of the containing anti-blocking composition was applied, and then, after drying them, ultraviolet rays were irradiated on both sides of the transparent film substrate 2 to cure the hard coat composition and the anti-blocking composition. As a result, a hard coat layer 3 having a thickness of 1 µm was formed on the upper surface of the transparent film base 2 and an anti-blocking layer 4 having a thickness of 1 µm was formed on the lower surface of the transparent film base 2.

Subsequently, on the upper surface of the hard coat layer 3, a diluent ("off-star Z7412" made by JSR Co., Ltd., refractive index 1.62) of an optical adjustment composition containing zirconia particles and an ultraviolet curable resin (acrylic resin) was applied, and the temperature was 80 deg. After drying for 3 minutes, ultraviolet rays were irradiated. Thereby, the optical adjustment layer 5 of 0.1 micrometer thickness was formed on the upper surface of the hard-coat layer 3.

As shown in Fig. 1A, thereby, a substrate laminate 7 comprising an anti-blocking layer 4, a transparent film substrate 2, a hard coat layer 3, and an optical adjustment layer 5 was obtained.

Subsequently, in the second step, the substrate laminate 7 was annealed using a heating furnace (vacuum heating device) 8. The furnace length of the heating furnace 8 was 30 m, and the conveyance speed of the substrate laminate 7 in the heating furnace 8 was 15 m/min. The tension in the conveyance direction of the substrate laminate 7 was 40 N. That is, in the second step, the substrate laminate 7 is formed so that the difference between the heat shrinkage in the MD direction and the TD direction after the heat resistance test A (to be described later) of heating the transparent conductive film 1 at 150° C. for 90 minutes is 0.05% or less. Annealed.

Thereafter, as shown in Fig. 1B, in the third step, an amorphous transparent conductive layer 6A having a thickness of 25 nm was formed on the upper surface of the optical adjustment layer 5 by sputtering. Specifically, first, a sintered body target containing indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) in a weight ratio of 70:30 is mounted on a parallel-plate wound-type magnetron sputtering device, and the substrate laminate ( While conveying 7), it was evacuated by vacuum evacuation until the partial pressure of water became 5×10 ^-4 Pa. Thereafter, the introduction amount of argon gas and oxygen gas was adjusted, and an amorphous transparent conductive layer 6A having a thickness of 25 nm was formed by DC sputtering at an output of 12.5 kW on the upper surface of the optical adjustment layer 5. Moreover, as a result of measuring the surface resistance of the amorphous transparent conductive layer 6A, it was 340 Ω/□.

As a result, as shown in Fig. 1B, a transparent conductive film 1 was prepared having the substrate laminate 7 and the amorphous transparent conductive layer 6A in order.

Examples 2 and 3 and Comparative Examples 1 to 4

The transparent conductive film 1 was manufactured by processing similarly to Example 1 except having changed the heating conditions (anneal conditions) of a 2nd process according to description of Table 1.

In addition, in each of Comparative Examples 1 to 4, it was described so that the difference between the heat shrinkage in the MD direction and the TD direction after the heat resistance test A (to be described later) of heating the transparent conductive film 1 at 150°C for 90 minutes was more than 0.05%. The laminate 7 was annealed.

(evaluation)

Each of the following items was evaluated. Table 1 shows the results.

1. Measurement of heat shrinkage difference

(Difference in heat shrinkage after heat test A)

<150°C and 90-minute heating in the present invention>

As shown by the virtual line in Fig. 1C, the transparent conductive film 1 immediately after production is heated at 150°C for 90 minutes using a heating furnace 8, and in the MD direction and TD direction before and after heating. The heat shrinkage in each was obtained, and their difference was calculated.

Specifically, first, the transparent conductive film 1 having the amorphous transparent conductive layer 6A is cut out to a width of 100 mm and a length of 100 mm (test piece), every 80 mm in each of the MD direction and the TD direction. Each of the lengths (mm) in the MD direction and the lengths (mm) in the TD direction were accurately measured using an Olympus digital small measuring microscope STM5 (manufactured by Olympus Optical Industry Co., Ltd.). Thereafter, the transparent conductive film 1 having the amorphous transparent conductive layer 6A was heated at 150°C for 90 minutes.

Thereafter, the transparent conductive film 1 was allowed to stand at 25°C (at room temperature) for 1 hour, and then the lengths of the MD and TD directions of the transparent conductive film 1 were measured again.

And based on the following formula, each of the thermal contraction rate (MD) in MD direction and the thermal contraction rate (TD) in TD direction was computed.

Heat shrinkage (MD) (%) = [[MD direction length between marks before heating (mm)-MD direction between marks after heating (mm)]/MD direction between marks before heating (mm)] × 100

Heat shrinkage (TD) (%) = [[TD length between marks before heating (mm)-TD direction between marks after heating (mm)]/TD direction between marks before heating (mm)] × 100

And the difference was calculated|required from the thermal contraction rate (MD) (%) and the thermal contraction rate (TD) (%).

(The difference of the heat shrinkage rate after the heat resistance test B)

<Heating at 130°C and 90 minutes in Patent Document 1>

The heat shrinkage rate difference of the transparent conductive film 1 was calculated|required by processing similarly to the heat resistance test A except having changed the heating temperature from 150 degreeC to 130 degreeC (heat resistance test B). In addition, the object of the heat resistance test B was made into comparative example 1 only.

2. Crack Evaluation

(The presence or absence of cracks after the heat resistance test C)

<Crystalization of partially crystallized transparent conductive layer after passing through an accelerated test (50°C, 150 hours, see Fig. 1C) assuming storage of a transparent conductive film>

(i) Acceleration test (formation of partially crystallized transparent conductive layer)

As shown in Fig. 1C, the transparent conductive film 1 immediately after the production shown in Fig. 1B (the transparent conductive film 1 immediately after the amorphous transparent conductive layer 6A was formed) was placed in a heating furnace 8 at 50°C. 150 hours was added. Thereby, the amorphous transparent conductive layer 6A was partially partially crystallized to obtain a partially crystallized transparent conductive layer 6B. In addition, the surface resistance of the partially crystallized transparent conductive layer 6B was 95 Ω/□.

(ii) Complete crystallization (complete crystallization of partially crystallized transparent conductive layer)

Thereafter, as shown in FIG. 1D, the transparent conductive film 1 is heated under the same conditions as the heat resistance test A (at 150°C for 90 minutes) to completely crystallize the partially crystallized transparent conductive layer 6B, thereby making crystallized transparent conductive It was set as the layer 6C (implementation of a 4th process).

Thus, a crystallized transparent conductive film 10 having a substrate laminate 7 and a crystallized transparent conductive layer 6C was produced.

And the crack in the crystallized transparent conductive layer 6C was confirmed with the optical microscope (magnification 20).

(The presence or absence of cracks after the heat resistance test D)

<Crystallization of the amorphous transparent conductive layer 6A of the transparent conductive film immediately after production (non-acceleration test performed)>

As shown in Fig. 1D, the transparent conductive film 1 immediately after the production shown in Fig. 1B (the transparent conductive film 1 immediately after the amorphous transparent conductive layer 6A is formed) is the same as the heat resistance test A (150°C). (90 minutes), the transparent conductive film 1 was heated, and the amorphous transparent conductive layer 6A was completely crystallized to obtain a crystallized transparent conductive layer 6C. That is, the amorphous transparent conductive layer 6A became the crystallized transparent conductive layer 6C without passing through the partially crystallized transparent conductive layer 6B (implementation of the fourth step).

Thus, a crystallized transparent conductive film 10 having a substrate laminate 7 and a crystallized transparent conductive layer 6C was produced.

And the crack in the crystallized transparent conductive layer 6C was confirmed with the optical microscope (magnification 20).

(Review)

1) About heat test A and B

The heating temperature 130°C of the heat resistance test B corresponds to the heating temperature described in Patent Document 1, and is lower than the heating temperature 150°C of the heat resistance test A corresponding to the heating test of the present invention (heating conditions are mild).

In Comparative Example 1, in the heat resistance test B (130°C), the difference between the heat shrinkage rate in the MD direction and the heat shrinkage rate in the TD direction was 0.01%, which was within the range of 0.05% or less, but in the heat resistance test A (150°C), the The difference is 0.08%, which is outside the range of 0.05% or less.

That is, the difference in the heat shrinkage rate of Comparative Example 1 measured in the heat resistance test A (150°C), which is more severe than the condition (130°C) described in Patent Document 1, falls outside the scope of the present invention. Therefore, as can be seen from the results of the heat resistance test C, the occurrence of cracks in the crystallized transparent conductive layer 6C of Comparative Example 1 was confirmed.

On the other hand, the difference in the heat shrinkage rates of Examples 1 to 3 measured in the heat resistance test A (150° C.) is 0.01%, 0.02%, and 0.05%, respectively, all of which fall within the scope of the present invention. As can be seen from the results, in any of Examples 1 to 3, no crack was observed in the crystallized transparent conductive layer 6C.

2) About heat resistance test C and D

Heat resistance test D (each example and each comparative example):

In the heat resistance test D, the amorphous transparent conductive layer 6A of the transparent conductive film immediately after production was crystallized without passing through the partially crystallized transparent conductive layer 6B without performing an accelerated test assuming storage. It is a test made of a crystallized transparent conductive layer (6C).

The crystallized transparent conductive layer 6C produced in this heat resistance test D, while the transparent substrate 2 is stretched by heating, the relatively flexible amorphous transparent conductive layer 6A follows the stretching of the transparent substrate 2. . Therefore, in any of Examples 1 to 3 and Comparative Examples 1 to 4, no crack was observed in the crystallized transparent conductive layer 6C.

Heat resistance test C (each comparative example):

On the other hand, in the heat resistance test C, the partially crystallized transparent conductive layer 6B is passed. Then, in each comparative example in the heat resistance test C, if the partially crystallized transparent conductive layer 6B is crystallized by heating, the partially crystallized transparent conductive layer 6B does not follow elongation by heating the transparent substrate 2. Therefore, cracks were confirmed in the crystallized transparent conductive layer 6C.

Heat resistance test C (each example):

On the other hand, in each example in the heat resistance test C, even if the partially crystallized transparent conductive layer 6B is crystallized by heating, the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction after heating at 150°C for 90 minutes. Since it is 0.05% or less, it is excellent in heat resistance, and generation of cracks in the crystallized transparent conductive layer 6C was not observed.

In addition, although the said invention was provided as embodiment of the illustration of this invention, this is only a mere illustration and it should not interpret it limitedly. Modifications of the present invention that are apparent by those skilled in the art are included in the claims hereinafter described.

Industrial availability

The transparent conductive film is used for various optical applications.

1: Transparent conductive film
2: Transparent substrate
3: Hard coat layer
4: Anti-blocking layer
5: optical adjustment layer
6: transparent conductive layer
6A: amorphous transparent conductive layer
6B: partially crystallized transparent conductive layer

Claims (8)

A transparent substrate and a transparent conductive layer are provided in order,
The transparent substrate contains a resin having a glass transition temperature of 130°C or higher,
The transparent conductive layer is amorphous,
The transparent conductive film characterized in that the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction after heating at 150° C. for 90 minutes is 0.05% or less. According to claim 1,
The resin has a linear expansion coefficient of 5.5 × 10 ^-5 /°C or higher and 8.0 × 10 ^-5 /°C or lower. The method according to claim 1 or 2,
The resin is a transparent conductive film, characterized in that at least one member selected from the group consisting of cycloolefin-based resins and polycarbonate resins. The method according to claim 1 or 2,
The transparent conductive layer is a transparent conductive film, characterized in that it contains an indium tin composite oxide. The method according to claim 1 or 2,
A transparent conductive film having a thickness of 20 µm or more and 100 µm or less. The method according to claim 1 or 2,
An anti-blocking layer, a hard coat layer and an optical adjustment layer are additionally provided,
A transparent conductive film, characterized in that the anti-blocking layer, the transparent substrate, the hard coat layer, the optical adjustment layer and the transparent conductive layer are arranged in order. The first step of preparing a transparent substrate,
A second step of annealing the transparent substrate, and
A third step of manufacturing a transparent conductive film having an amorphous transparent conductive layer on the transparent substrate and sequentially comprising the transparent substrate and the transparent conductive layer is provided.
In the second step, the transparent base material is annealed such that the difference between the heat shrinkage in the MD direction and the heat shrinkage in the TD direction after heating the transparent conductive film at 150° C. for 90 minutes is 0.05% or less. The manufacturing method of the transparent conductive film mentioned above. The method of claim 7,
In the second step, the method for producing a transparent conductive film is characterized in that the transparent substrate is heated at less than 145°C for 1 minute or more and 5 minutes or less.

Images