JPWO2019130842A1 - Light-transmitting conductive film, its manufacturing method, dimming film, and dimming member - Google Patents

Abstract

The light-transmitting conductive film extends in a first direction and a second direction orthogonal to the first direction, and includes a base film and a light-transmitting conductive layer. When the thermomechanical analysis step of heating the light-transmitting conductive film from 20 ° C. to 160 ° C. and then lowering the temperature to 20 ° C. is carried out, the in-plane dimensional change rate R represented by the following formula is 0.55% or less. Is. R = (ΔL12 + ΔL22) 1/2 However, ΔL1 indicates the dimensional change rate (%) before and after the analysis step in the first direction, and ΔL2 is the dimensional change rate (%) before and after the analysis step in the second direction. ) Is shown.

Description

The present invention relates to a light transmissive conductive film, a method for producing the same, and a light control film and a light control member provided with the same.

In recent years, there has been an increasing demand for dimming devices such as smart windows due to the reduction of heating / cooling load and design. The dimmer is used for various purposes such as window glass of buildings and vehicles, partitions, and interiors.

As a light control film used in a light control device, for example, Patent Document 1 proposes a film having two transparent conductive resin base materials and a light control layer sandwiched between two transparent conductive resin base materials. (See, for example, Patent Document 1).

The dimming film of Patent Document 1 enables dimming by adjusting the absorption and scattering of light passing through the dimming layer by applying an electric field. As the transparent conductive resin base material of such a light control film, a film in which a transparent electrode made of indium tin oxide composite oxide (ITO) is laminated on a supporting base material such as a polyester film is adopted.

WO2008 / 075773

The light control film may be used by being attached to a large glass (for example, a window glass of 1 to 10 m ² ). Specifically, a light control film having substantially the same size as the glass is placed on the glass via a thermosetting or heat meltable adhesive, and the light control film is formed by heat curing or heat melting. Stick it on the glass.

However, since the light control film after sticking is heated, there is a problem that it shrinks more than the state before heating. As a result, there are places where the light control film is not attached to the glass (particularly the peripheral end). This non-attached portion becomes more conspicuous as the area of the target glass increases.

An object of the present invention is to provide a light transmissive conductive film capable of reducing the area not attached to an object, a method for producing the same, a light control film, and a light control member.

The present invention [1] is a light-transmitting conductive film extending in a first direction and a second direction orthogonal to the first direction, comprising a base film and a light-transmitting conductive layer, and the light. When the thermomechanical analysis step of heating the transmissive conductive film from 20 ° C. to 160 ° C. and then lowering the temperature to 20 ° C. was carried out, the in-plane dimensional change rate R represented by the following formula was 0.55% or less. Includes a light-transmitting conductive film.

R = (ΔL ₁ ² + ΔL ₂ ² ) ^1/2
(However, ΔL ₁ indicates the dimensional change rate (%) before and after the analysis step in the first direction, and ΔL ₂ indicates the dimensional change rate (%) before and after the analysis step in the second direction.)
The present invention [2] includes the light-transmitting conductive film according to [1], wherein both the absolute value of ΔL _{1 and} the absolute value of ΔL ₂ are 0.50 or less.

The present invention [3] includes the light-transmitting conductive film according to [1] or [2], wherein at least one of ΔL ₁ and ΔL ₂ has a positive value.

The present invention [4] includes the light-transmitting conductive film according to [3], wherein ΔL ₁ and ΔL ₂ are both positive values.

In the present invention [5], the base film contains the light-transmitting conductive film according to any one of [1] to [4], which is a film that has been heat-treated in an air environment. ..

In the present invention [6], the base film includes the light-transmitting conductive film according to any one of [1] to [5], which is a polyester-based film.

The present invention [7] comprises, in order, a first light-transmitting conductive film, a dimming functional layer, and a second light-transmitting conductive film, the first light-transmitting conductive film and / or the first. The light transmissive conductive film of No. 2 includes a light control film which is the light transmissive conductive film according to any one of [1] to [6].

The present invention [8] includes a dimming member including a protective member and the dimming film according to [7] attached to the protective member.

The present invention [9] is a method for producing a light-transmitting conductive film according to any one of [1] to [6], wherein the base film is heated in an air environment, and then The present invention includes a method for producing a light-transmitting conductive film, comprising a step of providing a light-transmitting conductive layer on the base film in a state where the base film is below 40 ° C.

The light-transmitting conductive film of the present invention has an in-plane dimensional change rate R of 0.55% or less when a thermomechanical analysis step of 20 ° C.-160 ° C.-20 ° C. is carried out.

Therefore, even if the light-transmitting conductive film of the present invention is attached to an object by heating, the light-transmitting conductive film can maintain a size close to that before heating. Therefore, the area that is not attached to the object can be reduced, and a light-transmitting conductive film of a desired size can be attached to the object.

Since the light control film and the light control member of the present invention include the light transmissive conductive film of the present invention, the area where the light transmissive conductive film is not attached to the object can be reduced.

The manufacturing method of the present invention can obtain a light-transmitting conductive film capable of reducing the area that is not attached to an object.

1A-B show an embodiment of the light-transmitting conductive film of the present invention, FIG. 1A shows a cross-sectional view, and FIG. 1B shows a perspective view. FIG. 2 shows a perspective view of a process of manufacturing the light-transmitting conductive film shown in FIG. 1A. FIG. 3 shows a cross-sectional view of a light control film including the light transmissive conductive film shown in FIG. 1A. 4A-D are process diagrams for manufacturing a dimming member using the dimming film shown in FIG. 2, FIG. 4A is a process for preparing a protective member, and FIG. 4B is thermosetting the protective member. A step of providing the adhesive layer, FIG. 4C shows a step of arranging the light control film on the thermosetting adhesive layer, and FIG. 4D shows a step of heat-curing the thermosetting adhesive layer.

In FIG. 1A, the paper thickness direction is the front-rear direction (first direction), the front side of the paper surface is the front side (one side of the first direction), and the back side of the paper surface is the rear side (the other side of the first direction). In FIG. 1A, the left-right direction of the paper surface is the left-right direction (width direction, the second direction orthogonal to the first direction), the left side of the paper surface is the left side (one side of the second direction), and the right side of the paper surface is the right side (the other side of the second direction). ). In FIG. 1A, the vertical direction of the paper surface is the vertical direction (thickness direction, the third direction orthogonal to the first direction and the second direction), and the upper side of the paper surface is the upper side (one side in the thickness direction, one side in the third direction). The lower side of the paper surface is the lower side (the other side in the thickness direction, the other side in the third direction). Specifically, it conforms to the direction arrows in each figure.

<One Embodiment>
1. 1. Light-transmitting conductive film The light-transmitting conductive film 1 according to an embodiment of the present invention is, for example, a film used for a light control film, a light control member, a light control device, etc. Light-transmitting conductive film for light). As shown in FIG. 1, the light-transmitting conductive film 1 has a film shape (including a sheet shape) having a predetermined thickness, and has a predetermined direction (front-back direction and left-right direction, that is, a direction perpendicular to the vertical direction (thickness direction)). , Has a flat upper surface (one surface in the thickness direction) and a flat lower surface (the other surface in the thickness direction). The light transmissive conductive film 1 is, for example, one component of a light control film 4 (described later, see FIG. 3), a light control member 6 (described later, see FIG. 4D), and a light control device (described later), that is, adjusting. It is not an optical film 4. That is, the light transmissive conductive film 1 is a component for manufacturing a dimming film 4 or the like, and is a device that does not include the dimming function layer 5 or the like, is distributed as a single component, and can be industrially used.

Specifically, the light-transmitting conductive film 1 includes a base film 2 and a light-transmitting conductive layer 3 in this order. That is, the light-transmitting conductive film 1 includes a base film 2 and a light-transmitting conductive layer 3 arranged on the upper side of the base film 2. Preferably, the light-transmitting conductive film 1 is composed of only the base film 2 and the light-transmitting conductive layer 3. Hereinafter, each layer will be described in detail.

2. 2. Base film The base film 2 is the lowermost layer of the light-transmitting conductive film 1 and is a support material for ensuring the mechanical strength of the light-transmitting conductive film 1. Further, the base film 2 is a support material having light transmission and flexibility. The base film 2 supports the light-transmitting conductive layer 3.

The base film 2 has a film shape (including a sheet shape).

The base film 2 is made of, for example, a polymer film. Examples of the material of the polymer film include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate and polyethylene naphthalate, and (meth) acrylic resins (acrylic resin and / or methacrylic resin) such as polymethacrylate. , Polyethylene, polypropylene, cycloolefin polymer and other olefin resins, such as polycarbonate resin, polyether sulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, polystyrene resin, norbornene resin and the like. These polymer films can be used alone or in combination of two or more. The base film 2 is preferably a polyester-based film formed of a polyester resin, and more preferably a polyethylene terephthalate film, from the viewpoints of light transmission, heat resistance, mechanical strength and the like.

The base film 2 is preferably a stretched film, and more preferably a biaxially stretched film, from the viewpoint of further excellent heat resistance and mechanical strength.

The base film 2 is preferably a film heat-treated in an air environment, and more preferably a biaxially stretched film heat-treated in an air environment, as will be described later. When such a base film 2 is used, the stress existing inside the base film 2 is relaxed. Therefore, when the light transmissive conductive film 1 is attached to an object by heating, the light transmissive conductive film 1 Excessive contraction can be suppressed.

The total light transmittance (JIS K-7105) of the base film 2 is, for example, 80% or more, preferably 85% or more, and for example, 100% or less, preferably 95% or less.

The haze (JIS K-7105) of the base film 2 is, for example, 2.0% or less, preferably 1.8% or less, more preferably 1.5% or less, still more preferably 1.2% or less. And, for example, 0.1% or more.

The thickness of the base film 2 is, for example, 2 μm or more, preferably 50 μm or more, more preferably 100 μm or more, and for example, 300 μm or less, preferably 250 μm or less. When the thickness of the base film 2 is equal to or greater than the above lower limit, more water contained in the polymer film can be imparted to the light-transmitting conductive layer 3 when the light-transmitting conductive layer 3 is formed. The crystallization of 3 can be suppressed. Therefore, the amorphous property of the light-transmitting conductive layer 3 can be maintained. Further, when the thickness of the base film 2 is at least the above lower limit, the strength of the light-transmitting conductive film 1 is excellent.

The thickness of the base film 2 can be measured using, for example, a film thickness meter.

A separator or the like may be provided on the lower surface of the base film 2.

3. 3. Light-transmitting conductive layer The light-transmitting conductive layer 3 is a transparent conductive layer that can be patterned by etching in a later step if necessary.

The light-transmitting conductive layer 3 has a film shape (including a sheet shape), and is arranged on the entire upper surface of the base film 2 so as to be in contact with the upper surface of the base film 2.

As the material of the light transmissive conductive layer 3, for example, at least selected from the group consisting of In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, and W. Examples include metal oxides containing one type of metal. The metal oxide may be further doped with the metal atoms shown in the above group, if necessary.

Examples of the light-transmitting conductive layer 3 include indium-based conductive oxides such as indium tin oxide composite oxide (ITO), and antimony-based conductive oxides such as antimony tin composite oxide (ATO). .. The light-transmitting conductive layer 3 contains an indium-based conductive oxide, and more preferably an indium tin oxide composite oxide (ITO), from the viewpoint of ensuring excellent conductivity and light transmission. That is, the light-transmitting conductive layer 3 is preferably an indium-based conductive oxide layer, and more preferably an ITO layer.

When ITO is used as the material of the light transmissive conductive layer 3, 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 preferably 3% by mass or more, more preferably 8% by mass or more, further preferably more than 10% by mass, and for example, 25% by mass or less, preferably 15% by mass or less, more preferably. It is 13% by mass or less. When the content of tin oxide is at least the above lower limit, crystallization can be more reliably suppressed while realizing excellent conductivity of the light-transmitting conductive layer 3. Further, when the tin oxide content is not more than the above upper limit, the stability of light transmission and conductivity can be improved.

The term "ITO" in the present specification may be any composite 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, W and Fe. , Pb, Ni, Nb, Cr, Ga and the like.

The light-transmitting conductive layer 3 may be either crystalline or amorphous, but is preferably amorphous, and more specifically, preferably an amorphous ITO layer. is there. When the light-transmitting conductive layer 3 is amorphous, it is excellent in crack resistance and scratch resistance, and thus is excellent in processability. That is, when the light-transmitting conductive film 1 is attached to an object to be attached (for example, a protective member such as glass described later), cracks and scratches generated in the light-transmitting conductive film 1 are suppressed. can do. Therefore, the appearance and characteristics of the attached light-transmitting conductive film 1 can be maintained satisfactorily.

The fact that the light-transmitting conductive layer 3 is amorphous or crystalline means that, for example, when the light-transmitting conductive layer 3 is an ITO layer, it is immersed in hydrochloric acid (concentration 5% by mass) at 20 ° C. for 15 minutes. It can be judged by washing and drying with water and measuring the resistance between terminals between about 15 mm. In the present specification, after the light-transmitting conductive film 1 is immersed in hydrochloric acid (20 ° C., concentration: 5% by mass), washed with water, and dried, the resistance between terminals of the light-transmitting conductive layer between 15 mm is 10 kΩ or more. In this case, it is assumed that the light-transmitting conductive layer is amorphous.

The surface resistance value of the light transmissive conductive layer 3 is, for example, 1Ω / □ or more, preferably 10Ω / □ or more, and for example, 200Ω / □ or less, preferably 100Ω / □ or less, more preferably. It is 85Ω / □ or less. If the surface resistance value of the light transmissive conductive layer 3 is within the above range, good electric drive can be realized even when used as a large-scale dimming device.

The specific resistance value of the light transmissive conductive layer 3 is, for example, 6 × 10 ^-4 Ω · cm or less, preferably 5.5 × 10 ^-4 Ω · cm or less, more preferably 5 × 10 ^-4 Ω · cm. Cm or less, more preferably 4.8 × 10 ^-4 Ω · cm or less, and for example, 3 × 10 ^-4 Ω · cm or more, preferably 3.5 × 10 ^-4 Ω · cm or more. More preferably, it is 4.0 × 10 ^-4 Ω · cm or more. When the specific resistance value of the light transmissive conductive layer 3 is not more than the above upper limit, good electric drive can be realized even when used as a large-scale dimming device. Further, when the specific resistance value is at least the above lower limit, the amorphous property of the light transmissive conductive layer 3 can be more reliably maintained.

The thickness of the light-transmitting conductive layer 3 is, for example, 10 nm or more, preferably 30 nm or more, more preferably 50 nm or more, and for example, 200 nm or less, preferably 150 nm or less, more preferably 100 nm or less. is there. The thickness of the light-transmitting conductive layer 3 can be measured, for example, by observing a cross section using a transmission electron microscope.

4. Method for Producing Light Transmissive Conductive Film Next, a method for manufacturing the light transmissive conductive film 1 will be described.

The method for producing the light-transmitting conductive film 1 is, for example, a preheating step of heating the base film 2 in an air environment, and then light transmission to the base film 2 in a state where the base film 2 is lower than 40 ° C. The present invention includes a conductive layer arranging step of providing the conductive conductive layer 3. The method for producing the light-transmitting conductive film 1 is preferably carried out by a roll-to-roll method as referred to in FIG.

In the preheating step, first, the base film 2 is prepared. For example, in the case of the roll-to-roll method, a base film 2 that is long in the transport direction (for example, the first direction) and is wound in a roll shape is used.

Preferably, the biaxially stretched base film 2 is prepared from the viewpoint of mechanical strength, heat resistance, and light transmission.

Subsequently, the base film 2 is heated in an air environment. That is, the base film 2 is heated before the light-transmitting conductive layer 3 is provided. The base film 2 is preferably heated by a roll-to-roll method. For example, in an air environment, the base film 2 wound in a long roll shape is unwound, transported while being heated, and then transported. Wind it into a long roll again.

By this heat treatment, the stress inherent in the base film 2 can be released, and the heat shrinkage at the time of attaching the light-transmitting conductive film 1 can be suppressed. In particular, since a strong internal stress is applied to the biaxially stretched film by stretching during its production, the thermal shrinkage of the biaxially stretched film as the base film 2 can be more reliably suppressed.

Further, since the film is heated in an atmospheric environment, it is possible to suppress wrinkles and scratches generated on the base film 2 and maintain a good appearance of the light-transmitting conductive film 1 as compared with heating under a vacuum. it can. That is, when the roll-shaped base film 2 is unwound from the roll or wound up, the atmosphere can be interposed between the laminated base films 2, so that adhesion and friction of the base film 2 can be suppressed. , Wrinkles and scratches can be suppressed. Further, when the base film 2 is transported, the air can be interposed between the transport roll (for example, the guide roll) and the base film 2, so that excessive adhesion with the transport roll can be suppressed. It can also suppress wrinkles and scratches. These suppressions are particularly effective for appearance in dimmers, which are often used in large areas.

The heating temperature is, for example, 100 ° C. or higher, preferably 130 ° C. or higher, more preferably 150 ° C. or higher, and for example, 220 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower. is there. The heating temperature is a set temperature of a heating facility (for example, an IR heater or a heating roll) for heating the base film 2.

The heating time is, for example, 0.3 minutes or more, preferably 0.5 minutes or more, more preferably 1 minute or more, and for example, 10 minutes or less, preferably 5 minutes or less. When the heating time is not more than the above upper limit, it is possible to suppress the generation of excess precipitates (oligomers, etc.) from the base film 2 and suppress the decrease in transparency and the increase in haze of the base film 2. it can. Further, when the heating time is not more than the above lower limit, the residual stress of the base film 2 can be sufficiently released, and the heat shrinkage at the time of attaching the light transmissive conductive film 1 can be more reliably suppressed. ..

In the conductive layer arranging step, for example, the light-transmitting conductive layer 3 is formed on the upper surface of the base film 2 by a dry method.

Examples of the dry method include a vacuum deposition method, a sputtering method, and an ion plating method. Preferably, a sputtering method is used.

In the sputtering method, the target and the adherend (base film 2) are placed facing each other in the chamber (deposition chamber) of the vacuum apparatus, and the gas ion is accelerated by applying a voltage while supplying gas to irradiate the target. Then, the target material is ejected from the target surface, and the target material is laminated on the surface of the adherend.

Examples of the sputtering method include a bipolar sputtering method, an ECR (electron cyclotron resonance) sputtering method, a magnetron sputtering method, and an ion beam sputtering method. Preferred is the magnetron sputtering method.

The power source used in the sputtering method may be, for example, a direct current (DC) power source, an alternating current medium frequency (AC / MF) power source, a high frequency (RF) power source, or a high frequency power source on which a direct current power source is superimposed.

Examples of the target include the above-mentioned metal oxides constituting the light-transmitting conductive layer 3. For example, when ITO is used as the material of the light transmissive conductive layer 3, a target made of ITO is used. The tin oxide (SnO ₂ ) content in the target is, for example, 0.5% by mass or more, preferably 3% by mass or more, more preferably 3% by mass or more, based on the total amount of tin oxide and indium oxide (In ₂ O ₃ ). , 8% by mass or more, more preferably more than 10% by mass, and for example, 25% by mass or less, preferably 15% by mass or less, more preferably 13% by mass or less.

Sputtering is preferably carried out under vacuum and its atmospheric pressure is, for example, 1.0 Pa or less, preferably 0.5 Pa or less, more preferably 0.2 Pa or less, and for example 0.01 Pa. That is all.

Examples of the gas introduced during sputtering include an inert gas such as Ar. Further, in this method, a reactive gas such as oxygen gas is used in combination. The ratio of the flow rate of the reactive gas to the flow rate of the inert gas (flow rate of the reactive gas (sccm) / flow rate of the inert gas (sccm)) is, for example, 0.1/100 or more and 5/100 or less.

The temperature of the base film 2 when forming the light-transmitting conductive layer 3 is less than 40 ° C., preferably 20 ° C. or lower, more preferably 10 ° C. or lower, still more preferably 5 ° C. or lower, and particularly preferably. Is less than 0 ° C., most preferably -3 ° C. or lower, and for example, −40 ° C. or higher, preferably −20 ° C. or higher. If the temperature of the base film 2 exceeds the above upper limit, the base film 2 is stretched in the transport direction due to the tension in the transport direction, and a large amount of stress remains in the base film 2 of the obtained light transmissive conductive film 1. To do. As a result, when the light-transmitting conductive film 1 is attached to the object, there is a risk of significant heat shrinkage.

To cool the base film 2, for example, the lower surface of the base film 2 is brought into contact with a cooling device (for example, a cooling roll).

In the roll-to-roll method, for example, the film-forming roll or the nip roll can be cooled to form a cooling roll. The temperature of the base film 2 is set to the set temperature of the cooling device.

The atmosphere during sputtering (inside the chamber) is preferably water-containing, and the ratio of water gas to the sputtering pressure (total pressure) (partial pressure of water gas (Pa) / sputtering pressure (Pa)) is, for example, 0.006 or more, preferably 0.008 or more, more preferably 0.01 or more, and for example, 0.3 or less, preferably 0.1 or less, more preferably 0.07 or less, More preferably, it is 0.05 or less. When the water content is within the above range, the light-transmitting conductive layer 3 can contain a small amount of water, and the crystallization of the light-transmitting conductive layer 3 can be suppressed.

As a result, the light-transmitting conductive film 1 including the base film 2 and the light-transmitting conductive layer 3 is obtained. The light-transmitting conductive layer 3 at this time is amorphous.

The total thickness of the obtained light-transmitting conductive film 1 is, for example, 2 μm or more, preferably 20 μm or more, and for example, 300 μm or less, preferably 200 μm or less.

The in-plane dimensional change rate R of the light-transmitting conductive film 1 is 0.55% or less, preferably 0.30% or less.

The in-plane dimensional change rate R is a thermomechanical analysis step of heating the light transmissive conductive film 1 from 20 ° C. to 160 ° C. and then lowering the temperature to 20 ° C. (the analysis step, hereinafter also abbreviated as "TMA"). It is the dimensional change rate in the diagonal direction (the direction intersecting both the first direction and the second direction) when the above is carried out, and is specifically represented by the following formula.

R = (ΔL ₁ ² + ΔL ₂ ² ) ^1/2
In the formula, ΔL ₁ indicates the dimensional change rate (%) before and after TMA in the front-back direction (first direction), and is specifically shown by the following formula.

ΔL ₁ = {(L ₁ ^′ −L ₁ ) / L ₁ } × 100 (%)
L ₁ indicates the anteroposterior length at 20 ° C. before TMA is performed, and L ₁ ′ indicates the anteroposterior length at 20 ° C. after TMA is performed.

In the formula, ΔL ₂ indicates the dimensional change rate (%) before and after TMA in the left-right direction (second direction), and is specifically represented by the following formula.

^{_{ΔL 2 = {(L 2 '}} -L 2) / L 2} × 100 (%)
L ₂ indicates the left-right length at 20 ° C. before TMA is performed, and L ₂ ′ indicates the left-right length at 20 ° C. after TMA is performed.

The absolute value of the dimensional change rate ΔL ₁ is, for example, 0.50 or less, preferably 0.30 or less. The dimensional change rate ΔL ₁ is, for example, −0.50 or more, preferably more than 0, and for example, 0.50 or less, preferably 0.30 or less.

The absolute value of the dimensional change rate ΔL ₂ is, for example, 0.50 or less, preferably 0.30 or less. Further, the dimensional change rate ΔL ₂ exceeds 0, preferably 0.10 or more, and is, for example, 0.50 or less, preferably 0.30 or less.

When the absolute value of the dimensional change rate ΔL _{1 and} the absolute value of the dimensional change rate ΔL ₂ are in the above ranges, the light transmissive when the light transmissive conductive film 1 is attached to the object by heating is light transmissive. Excessive shrinkage of the conductive film 1 can be prevented, and the size close to the state before heating can be maintained. In particular, if the absolute value of the dimensional change rate ΔL _{1 and} the absolute value of the dimensional change rate ΔL ₂ are both in the above range, the attached light-transmitting conductive film 1 is close to the state before heating. The size can be more reliably maintained or larger.

Further, the dimensional change rate ΔL ₁ and the dimensional change rate ΔL ₂ may be either a positive value or a negative value, but preferably at least one of the dimensional change rate ΔL ₁ and the dimensional change rate ΔL ₂ is It is a positive value, and more preferably, the dimensional change rate ΔL ₁ and the dimensional change rate ΔL ₂ are both positive values. When the dimensional change rate is a positive value, the dimensional change of the light-transmitting conductive film 1 after TMA indicates expansion.

If at least one of the dimensional change rates is a positive value, when the light-transmitting conductive film 1 is attached to the object by heating, the attached light-transmitting conductive film 1 is in a state before heating. It is possible to more reliably maintain a size close to. In particular, if both of the dimensional change rates are positive values, the attached light-transmitting conductive film 1 can be expanded by heating to a size larger than the size before heating. Therefore, the light-transmitting conductive film 1 can be reliably attached to the entire surface of one surface of the object.

In TMA, the load applied to the light-transmitting conductive film 1 is 19.6 mN, and the size of the light-transmitting conductive film 1 (measurement sample) at the time of measurement is 20 mm on the long side (direction in which the load is applied). The short side is 3 mm. Other conditions are the same as in the examples.

In the case of the roll-to-roll method, for example, the transport direction (MD direction) for transporting the base film 2 is the front-rear direction (first direction), and the orthogonal direction (TD direction) orthogonal to the transport direction is the left-right direction (first direction). (Two directions) (see Fig. 2).

Further, a heating step (hereinafter, also simply referred to as “the heating step”) is carried out in which the light transmissive conductive film 1 is heated from 20 ° C. to 150 ° C. and then lowered to 20 ° C. according to JIS C 2151. The absolute value of the dimensional change rate ΔM ₁ before and after heating in the front-rear direction is, for example, 0.50% or less, preferably less than 0.30%. The dimensional change rate ΔM ₁ is, for example, −0.50% or more, preferably −0.30% or more, and for example, 0.50% or less, preferably less than 0%. ..

Dimensional change .DELTA.M ₁ is, M ₁ a front-rear length at 20 ° C. before carrying out said heating _step, the front-rear length at 20 ° C. after performing the heating step as M _{1 ',} the following formula Is shown.

ΔM ₁ = {(M ₁ ^′ −M ₁ ) / M ₁ } × 100 (%)
Further, when the heating step is performed, the absolute value of the dimensional change rate ΔM ₂ before and after heating in the left-right direction is, for example, 0.50% or less, preferably less than 0.30%, more preferably 0. It is 10% or less. The dimensional change rate ΔM ₂ is, for example, −0.50% or more, preferably −0.30% or more, and for example, 0.50% or less, preferably less than 0%.

Dimensional change .DELTA.M ₂ is, M ₂ in the lateral direction length in 20 ° C. before carrying out said heating _step, the lateral direction length in 20 ° C. after performing the heating step as M _{2 ',} the following formula Is shown.

ΔM ₂ = {(M ₂ ^′ −M ₂ ) / M ₂ } × 100 (%)
Further, at least one of the absolute values of the dimensional change rate ΔM ₁ and the dimensional change rate ΔM ₂ is preferably less than 0.30%. More preferably, the absolute value of ΔM _{1 and} the absolute value of ΔM ₂ are both less than 0.30%.

The method according to JIS C 2151 is a method of heating the light-transmitting conductive film 1 without applying a load such as a tensile load to the light-transmitting conductive film 1.

The dimensional change rate ΔM ₁ and the dimensional change rate ΔM ₂ may be either positive or negative values, but preferably at least one of the dimensional change rate ΔM ₁ and the dimensional change rate ΔM ₂ is negative. It is a value, and more preferably, the dimensional change rate ΔM ₁ and the dimensional change rate ΔM ₂ are both negative values. When the dimensional change rate is a negative value, the dimensional change of the light-transmitting conductive film 1 after the heating step indicates shrinkage.

The haze (JIS K-7105) of the light transmissive conductive film 1 is, for example, 2.0% or less, preferably 1.8% or less, more preferably 1.5% or less, still more preferably 1.2. % Or less, and for example, 0.1% or more. When the haze of the light-transmitting conductive film 1 is within the above range, it can be suitably used as a light-transmitting conductive film for dimming.

The light-transmitting conductive film 1 can be etched as necessary to pattern the light-transmitting conductive layer 3 in a predetermined shape.

5. Method for manufacturing a light control film Next, a method for manufacturing a light control film 4 using the light transmissive conductive film 1 will be described with reference to FIG.

The method for manufacturing the light control film 4 includes, for example, a step of manufacturing two light transmissive conductive films 1 and then a step of sandwiching the light control functional layer 5 between the two light transmissive conductive films 1.

First, two light-transmitting conductive films 1 are manufactured. It is also possible to prepare two light-transmitting conductive films 1 by cutting one light-transmitting conductive film 1.

The two light-transmitting conductive films 1 are a first light-transmitting conductive film 1A and a second light-transmitting conductive film 1B.

Next, for example, the dimming function layer 5 is formed on the upper surface (surface) of the light transmitting conductive layer 3 in the first light transmitting conductive film 1A by wet treatment.

For example, the liquid crystal composition or a solution thereof is applied to the upper surface of the light-transmitting conductive layer 3 in the first light-transmitting conductive film 1A to form a coating film. The liquid crystal composition is not limited as long as it can be used for dimming, and examples thereof include known ones, and examples thereof include the liquid crystal dispersion resin described in JP-A-8-194209.

Subsequently, the second light-transmitting conductive film 1B is laminated on the upper surface of the coating film so that the light-transmitting conductive layer 3 of the second light-transmitting conductive film 1B and the coating film are in contact with each other. As a result, the coating film is sandwiched between the two light-transmitting conductive films 1, that is, the first light-transmitting conductive film 1A and the second light-transmitting conductive film 1B.

After that, the coating film is subjected to an appropriate treatment (for example, heat drying treatment, photocuring treatment) as necessary to form the dimming functional layer 5. The dimming function layer 5 is arranged between the light transmitting conductive layer 3 of the first light transmitting conductive film 1A and the light transmitting conductive layer 3 of the second light transmitting conductive film 1B.

As a result, a light control film 4 including the first light transmissive conductive film 1A, the dimming function layer 5, and the second light transmissive conductive film 1B in this order is obtained.

6. Method for Manufacturing Dimming Member Next, a method for manufacturing the dimming member 6 using the dimming film 4 will be described with reference to FIGS. 4A-D.

The method for manufacturing the light control member 6 includes, for example, a step of forming a thermosetting adhesive layer 8 on the protective member 7, a step of arranging a light control film 4 on the thermosetting adhesive layer 8, and heat curable adhesion. It includes a step of heating and curing the agent layer 8.

First, as shown in FIG. 4A, the protective member 7 is prepared. The protective member 7 is an object to which the light control film 4 is attached, and examples thereof include a window glass, a partition, and an interior. Specifically, as the protective member 7, a rigid transparent plate having an appropriate mechanical strength and thickness is used, and examples thereof include a glass plate and a reinforced plastic plate (for example, a polycarbonate resin).

Subsequently, as shown in FIG. 4B, the thermosetting adhesive layer 8 is formed on the protective member 7. For example, a liquid thermosetting adhesive composition is applied to the entire upper surface (surface) of the protective member 7.

Examples of the thermosetting adhesive composition include an epoxy-based thermosetting adhesive composition and an acrylic-based thermosetting adhesive composition. As the thermosetting adhesive composition, any resin can be used as long as the adhesion between the light control film 4 and the protective member 7 can be maintained after the thermosetting, and the present invention is not limited to the above examples.

Examples of the coating method include a method using an applicator, potting, cast coating, spin coating, roll coating and the like.

Next, as shown in FIG. 4C, the light control film 4 is arranged on the thermosetting adhesive layer 8. That is, the light control film 4 is arranged on the upper surface of the protective member 7 via the thermosetting adhesive layer 8.

At this time, the light control film 4 is arranged so as to have substantially the same size as the protective member 7. Specifically, the light control film 4 is cut so as to have substantially the same size as the protective member 7 (same front-rear direction length and same left-right direction length), and subsequently adjusted with the peripheral edge of the protective member 7. The light control film 4 is arranged on the upper surface of the thermosetting adhesive layer 8 so that the peripheral edge of the optical film 4 coincides with the peripheral edge of the optical film 4 when projected in the vertical direction.

Next, as shown in FIG. 4D, the thermosetting adhesive layer 8 is heat-cured.

The heating temperature is, for example, 80 ° C. or higher, preferably 100 ° C. or higher, and for example, 180 ° C. or lower, preferably 160 ° C. or lower.

The heating time is, for example, 5 minutes or more, preferably 20 minutes or more, more preferably 30 minutes or more, and for example, 600 minutes or less, preferably 300 minutes or less.

The heat curing may be carried out in an air environment or a vacuum environment, or an appropriate pressure may be applied.

Then, the light control film 4 attached to the protective member 7 is cooled to room temperature (5 to 35 ° C.).

As a result, the thermosetting adhesive layer 8 is thermally cured to form the adhesive layer 8a. As a result, the light control film 4 is attached (fixed) to the protective member 7 via the adhesive layer 8a.

At this time, the light-transmitting conductive film 1 and, by extension, the light control film 4 maintain or expand in a plan view size close to the state before heating. When the light control film 4 expands, as shown by a virtual line, the end portion (protruding portion 9) of the light control film 4 protrudes laterally from the edge of the protective member 7 in the surface direction. That is, the peripheral edge of the light control film 4 is located on the outer side of the peripheral edge of the protective member 7.

As a result, as shown in FIG. 4D, a dimming member 6 including a protective member 7, an adhesive layer 8a provided on the upper surface thereof, and a dimming film 4 arranged on the upper surface of the adhesive layer 8a is obtained.

After that, when the light control film 4 expands, the light control film 4 is cut, if necessary, as shown by the virtual line in FIG. 4D. That is, the end portion of the light control film 4 is cut in the vertical direction to remove the protruding portion 9 of the light control film 4. As a result, a dimming member 6 in which the protective member 7 and the dimming film 4 have substantially the same size can be obtained.

The dimming member 6 is used, for example, as an electrically driven dimming device (not shown) by mounting a wiring (not shown), a power supply (not shown), and a control device (not shown). .. Examples of the electric drive type include an electric field drive type and a current drive type. As an example, in an electric field-driven dimmer, the light-transmitting conductive layer 3 in the first light-transmitting conductive film 1A and the light-transmitting conductive layer in the second light-transmitting conductive film 1B are provided by wiring and a power source. A voltage is applied to 3 and thereby an electric field is generated between them. Then, by controlling the above-mentioned electric fields based on the control device, the dimming function layer 5 located between them is in an oriented state or an irregular state to transmit or block light (). Or scatter).

The light transmissive conductive film 1 and the light control film 4 have an in-plane dimensional change rate R of 0.55% or less when a thermomechanical analysis step (TMA) of 20 ° C.-160 ° C.-20 ° C. is performed. is there. Therefore, even if the light-transmitting conductive film 1 is attached to the protective member 7 (object) by heating, the light-transmitting conductive film 1 can maintain a size close to the state before heating. Therefore, the area that is not attached to the protective member 7 can be reduced, and the light-transmitting conductive film 1 of a desired size can be attached to the object.

Although this mechanism is not clear, when the light-transmitting conductive film 1 is attached to the protective member 7 by heating via a heat-curable adhesive, and when a tensile load is applied to the light-transmitting conductive film 1. It is presumed that the expansion and contraction of the light-transmitting conductive film 1 exhibits the same behavior as in the case where the TMA is heated.

In the dimming member 6 using the dimming film 4, the area where the dimming film 4 is not attached is reduced on the upper surface (attached surface) of the protective member 7. Therefore, it is possible to have a dimming function (particularly at the end portion) in a large area of the protective member 7.

7. Modification Example In the embodiment shown in FIG. 1, the light-transmitting conductive layer 3 is directly arranged on the upper surface of the base film 2, but for example, although not shown, the function is on the upper surface and / or the lower surface of the base film 2. Layers can be provided.

That is, for example, the light-transmitting conductive film 1 includes a base film 2, a functional layer arranged on the upper surface of the base film 2, and a light-transmitting conductive layer 3 arranged on the upper surface of the functional layer. Can be done. Further, for example, the light-transmitting conductive film 1 includes a base film 2, a light-transmitting conductive layer 3 arranged on the upper surface of the base film 2, and a functional layer arranged on the lower surface of the base film 2. Can be prepared. Further, for example, the functional layer and the light-transmitting conductive layer 3 may be provided in this order on the upper side and the lower side of the base film 2.

Examples of the functional layer include an easy-adhesion layer, an undercoat layer, and a hardcoat layer. The easy-adhesion layer is a layer provided to improve the adhesion between the base film 2 and the light-transmitting conductive layer 3. The undercoat layer is a layer provided for adjusting the reflectance and optical hue of the light-transmitting conductive film 1. The hard coat layer is a layer provided to improve the scratch resistance of the light-transmitting conductive film 1. These functional layers may be used alone or in combination of two or more.

In the embodiment shown in FIG. 4D, the dimming member 6 having the adhesive layer 8a and the dimming film 4 on the upper surface of the protective member 7 is shown. For example, although not shown, the upper surface of the dimming film 4 is shown. Further, the adhesive layer 8a and the protective member 7 may be provided in this order.

Further, before attaching the light control film 4 to the protective member 7, wiring may be arranged in advance on the outer peripheral portion of the light transmissive conductive layer 3 of the light control film 4.

Further, in FIGS. 4A-D, in the method of manufacturing the light control member 6, the light control film 4 is attached to the protective member 7 by using the thermosetting adhesive layer 8, but the adhesive layer is heated. It is not limited to the thermosetting adhesive layer as long as it can be adhered by. For example, although not shown, the light control film 4 may be attached to the protective member 7 using a heat-meltable adhesive. That is, the method for manufacturing the light control member 6 includes, for example, a step of forming a heat-meltable adhesive layer on the protective member 7, a step of arranging the light control film 4 on the heat-meltable adhesive layer, and heat-meltable adhesion. It may include a step of heating and melting the agent layer.

As a method of forming the heat-meltable adhesive layer, for example, a sheet made of the heat-meltable adhesive composition is laminated on the entire upper surface of the protective member 7.

Examples of the heat-meltable adhesive composition include thermoplastic resin compositions such as ethylene-vinyl acetate-based compositions, polyolefin-based compositions, polyamide-based compositions, polyester-based compositions, polypropylene-based compositions, and polyurethane-based compositions. Can be mentioned. These may be used alone or in combination of two or more. Such a heat-meltable adhesive composition is used, for example, as a hot-melt adhesive.

The heating temperature of the thermosetting adhesive layer is, for example, the same as the heating temperature of the thermosetting adhesive layer 8 described above.

<Other Embodiments>
In the above-described embodiment, the light-transmitting conductive film 1 is exemplified as the light-transmitting conductive film for dimming), but for example, the light-transmitting conductive film can be applied to applications other than dimming. it can.

Specifically, the light-transmitting conductive film is provided in, for example, an optical device such as an image display device (LCD, organic EL). Preferably, the light-transmitting conductive film is used as a base material for a touch panel. Examples of the touch panel type include various methods such as an optical method, an ultrasonic method, a capacitance method, and a resistance film method, and are particularly preferably used for a capacitance type touch panel.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples as long as the gist of the present invention is not exceeded, and various modifications and modifications are made based on the technical idea of the present invention. Is possible. In addition, specific numerical values such as the compounding ratio (content ratio), physical property values, and parameters used in the following description are the compounding ratios corresponding to those described in the above-mentioned "Form for carrying out the invention". Content ratio), physical property values, parameters, etc. can be replaced with the upper limit (numerical value defined as "less than or equal to" or "less than") or lower limit (numerical value defined as "greater than or equal to" or "excess"). it can.

Example 1
As a light-transmitting base film, a long polyethylene terephthalate (PET) film (thickness 188 μm, biaxially stretched film) was prepared in the first direction (conveyance direction, MD).

The PET film was heated in the air at 170 ° C. for 1 minute by a roll-to-roll method (preheating).

Next, the heated PET film was placed in a roll-to-roll sputtering apparatus, and a light-transmitting conductive layer made of amorphous ITO having a thickness of 65 nm was formed by a DC magnetron sputtering method. As a sputtering condition, the temperature of the PET film was set to −5 ° C. The atmosphere during sputtering was a vacuum atmosphere (flow rate ratio: Ar: O ₂ = 100: 3.3) with an atmospheric pressure of 0.2 Pa in which Ar and O ₂ were introduced, and the water content (moisture gas / total pressure) was It was set to 0.05. As a target, a sintered body of 12% by mass of tin oxide and 88% by mass of indium oxide was used.

Example 2
The thickness of the PET film was 50 μm, the temperature of the PET film in sputtering was set to 0 ° C., and the atmosphere during sputtering was a vacuum atmosphere with Ar and O ₂ introduced at a pressure of 0.4 Pa (flow ratio is Ar: O ₂ =). 100: 3.0), and the same as in Example 1 except that a sintered body of 10% by mass of tin oxide and 90% by mass of indium oxide was used as a target and the thickness of the light-transmitting conductive layer was 25 nm. In the same manner, a light-transmitting conductive film was produced.

Comparative Example 1
A light-transmitting conductive film was produced in the same manner as in Example 1 except that the PET film was not preheated.

Comparative Example 2
Except that the temperature of the PET film in sputtering was set to 140 ° C., the water content was set to 0.005, and after the formation of the light-transmitting conductive layer, post-heating was further carried out in the atmosphere at 170 ° C. for 2 minutes. , A light-transmitting conductive film was produced in the same manner as in Example 2.

(Evaluation)
(1) Thickness The thickness of the PET film (base film) was measured using a film thickness meter (manufactured by Ozaki Seisakusho Co., Ltd., device name "Digital Dial Gauge DG-205"). The thickness of the ITO layer (light transmissive conductive layer) was measured by cross-sectional observation using a transmission electron microscope (manufactured by Hitachi, Ltd., device name "HF-2000").

(2) Measurement of Dimensional Change by Thermomechanical Analysis (TMA) The light-transmitting conductive films of each Example and each Comparative Example were cut into strips having a long side of 20 mm and a short side of 3 mm and used as measurement samples. When measuring the dimensional change in the MD direction (first direction), the MD direction is the long side, the TD direction (the direction orthogonal to the MD direction, the second direction) is the short side, and the TD direction. When measuring the dimensional change of, the cut was made so that the TD direction was the long side and the MD direction was the short side. As a result, a measurement sample for measuring the dimensional change in each direction was prepared.

The measurement sample is set in a thermomechanical analyzer (“TMA / SS71000” manufactured by SII Technology Co., Ltd.), the temperature is raised from 20 ° C to 160 ° C in each of the MD direction and the TD direction, and the temperature is further lowered to 20 ° C. The dimensional change rate at that time was measured.

That is, the MD direction length at 20 ° C. before the temperature rise is L ₁ , the MD direction length at 20 ° C. after the temperature rise is L ₁ ^′ , and the dimensional change rate ΔL ₁ (%) in the MD direction is “{(L). was calculated by the equation of ^{_{1 '-L 1) / L 1}} } × 100 (%) ". Further, the TD direction length at 20 ° C. before the temperature rise is M ₂ , the TD direction length at 20 ° C. after the temperature rise is L ₂ ^′ , and the dimensional change rate ΔL ₂ (%) in the TD direction is “{(L). ^{_{2 '-L 2) / L 2}} } was calculated by the equation of × 100 (%) ". Further, the in-plane dimensional change rate R of the entire measurement sample was calculated by the formula "{(ΔL ₁ ) ² + (ΔL ₂ ) ² } ^1/2 ".

The conditions for thermomechanical analysis were as follows.

Measurement mode: Tension method Load: 19.6mN
Temperature rise rate: 10 ° C / min
Measurement atmosphere: Air (flow rate 200 ml / min)
Chucking distance: 10 mm
(3) Measurement of Dimensional Change Rate by JIS C 2151 The light-transmitting conductive film of each Example and each Comparative Example is 10 cm in the MD direction (first direction) and in the TD direction (direction orthogonal to the MD direction, second direction). A sample was prepared by cutting into 10 cm. The temperature at this time was 20 ° C.

According to JIS C 2151, the sample was heated in a hot air oven at 150 ° C. for 30 minutes and then lowered to 20 ° C. The dimensional change rate after this high temperature treatment was measured in each of the MD direction and the TD direction.

That is, the length in the MD direction at 20 ° C. before the temperature rise is M ₁ , the length in the MD direction at 20 ° C. after the temperature rise is M ₁ ^′ , and the dimensional change rate ΔM ₁ (%) in the MD direction is “{(. It was calculated by the equation of ^{_{M 1 '-M 1) / M}} 1} × 100 (%) ". Further, the TD direction length at 20 ° C. before the temperature rise is M ₂ , the TD direction length at 20 ° C. after the temperature rise is M ₂ ^′ , and the dimensional change rate ΔM ₂ (%) in the TD direction is “{(M). ^{_{2 '-M 2) / M 2}} } was calculated by the equation of × 100 (%) ".

(4) Adhesion test to glass A thermosetting resin (acrylic adhesive) was applied to the entire surface of a commercially available glass plate (length 30 cm in the front-rear direction x length 25 cm in the left-right direction). Next, the light-transmitting conductive films of Examples and Comparative Examples having the same size as the glass plate are prepared, and each light-transmitting conductive film has a peripheral edge of the glass plate and a peripheral edge of the light-transmitting conductive film. They were placed on top of the thermocurable adhesive so that they match, and then heated at 150 ° C. for 60 minutes in an air environment. As a result, the light-transmitting conductive film was attached to the glass plate.

The case where the entire surface of one surface of the glass is completely covered with the light-transmitting conductive film 1 and the protrusion of the edge of the light-transmitting conductive film is at a level that does not hinder practical use is evaluated as 〇. However, the edge of one side of the glass was slightly exposed, but when it was at a level that did not hinder practical use, it was evaluated as Δ, and the edge of one side of the glass was largely exposed for practical use. The case where there was a problem was evaluated as x.

In Example 1, the attached light-transmitting conductive film was slightly expanded in the vertical direction and the horizontal direction as compared with the glass plate. Therefore, by cutting the expanded film end, the entire glass plate was covered. , It can be seen that a light-transmitting conductive film having the same size as the glass plate can be attached.

(5) Amorphous The light-transmitting conductive films of Examples and Comparative Examples were heated at 80 ° C. for 20 hours in an air environment. Then, the heated light-transmitting conductive film was immersed in hydrochloric acid (concentration: 5% by mass) for 15 minutes, washed with water and dried, and the resistance between the two terminals between about 15 mm of each conductive layer was measured. When the resistance between the two terminals between 15 mm exceeded 10 kΩ, it was judged to be amorphous and evaluated as 〇. When it did not exceed 10 kΩ, it was judged to be crystalline and evaluated as x. The results are shown in Table 1.

(6) Appearance The surface of the light-transmitting conductive film of each Example and each Comparative Example was observed with the naked eye. When wrinkles and streaks were not completely observed on the film surface, it was evaluated as ◎, and when wrinkles and streaks were slightly observed, it was evaluated as 〇 when it was at a level that did not cause any trouble as a dimming device. , Slightly large wrinkles and streaks were observed, but the case where the level did not cause a big problem as a dimming device was evaluated as △, and the case where wrinkles and streaks at a level that could not be used as a dimming device were observed was ×. I evaluated it. The results are shown in Table 1.

The above invention has been provided as an exemplary embodiment of the present invention, but this is merely an example and should not be construed in a limited manner. Modifications of the present invention that will be apparent to those skilled in the art are included in the claims below.

The light-transmitting conductive film of the present invention can be applied to various industrial products, and is preferably used, for example, as a light control film provided in a light control member, a touch panel base material provided in an image display device, or the like. ..

1 Light-transmitting conductive film 2 Base film 3 Light-transmitting conductive layer 4 Dimming film 5 Dimming functional layer 6 Dimming member 7 Protective member

Claims (9)

A light-transmitting conductive film extending in a first direction and a second direction orthogonal to the first direction.
A base film and a light-transmitting conductive layer are provided.
When the thermomechanical analysis step of heating the light-transmitting conductive film from 20 ° C. to 160 ° C. and then lowering the temperature to 20 ° C. was carried out, the in-plane dimensional change rate R represented by the following formula was 0.55%. A light-transmitting conductive film characterized by the following.
R = (ΔL ₁ ² + ΔL ₂ ² ) ^1/2
(However, ΔL ₁ indicates the dimensional change rate (%) before and after the analysis step in the first direction, and ΔL ₂ indicates the dimensional change rate (%) before and after the analysis step in the second direction.) The light-transmitting conductive film according to claim 1, wherein both the absolute value of ΔL _{1 and} the absolute value of ΔL ₂ are 0.50 or less. The light-transmitting conductive film according to claim 1 or 2, wherein at least one of ΔL ₁ and ΔL ₂ has a positive value. The light-transmitting conductive film according to claim 3, wherein both ΔL ₁ and ΔL ₂ have positive values. The light-transmitting conductive film according to claim 1 or 2, wherein the base film is a film that has been heat-treated in an air environment. The light-transmitting conductive film according to claim 1 or 2, wherein the base film is a polyester-based film. A first light-transmitting conductive film, a dimming function layer, and a second light-transmitting conductive film are provided in this order.
The adjustment, wherein the first light-transmitting conductive film and / or the second light-transmitting conductive film is the light-transmitting conductive film according to any one of claims 1 to 6. Optical film. Protective material and
A dimming member comprising the dimming film according to claim 7, which is attached to the protective member. The method for producing a light-transmitting conductive film according to any one of claims 1 to 6.
The process of heating the base film in an air environment, and
Next, a method for producing a light-transmitting conductive film, which comprises a step of providing a light-transmitting conductive layer on the base material film in a state where the base film is below 40 ° C.

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