JP6744140B2 - Transparent conductive film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transparent conductive film, specifically, a transparent conductive film suitably used for optical applications.

Conventionally, a transparent conductive film having a transparent conductor layer made of indium tin composite oxide (ITO) or the like has been used for optical applications such as a touch panel.

For example, a transparent conductive layer is patterned, and a transparent conductive film having an undercoat layer on a non-patterned portion having no transparent conductive layer is disclosed (for example, see Patent Document 1). The transparent conductive film of Patent Document 1 suppresses the reflectance difference between the patterned portion and the non-patterned portion of the transparent conductor layer to be small and has a good appearance.

JP, 2009-76432, A

By the way, in recent years, along with the versatility of the touch panel, there has been a demand for wet heat durability in which the performance of the transparent conductive film is unlikely to deteriorate when used in a high temperature and high humidity environment. For example, it is required that cracks do not occur even when left in an environment of 85°C and 85%RH for a long time.

Therefore, in the transparent conductive film of Patent Document 1, it is considered to improve the wet heat durability by hardening the undercoat layer. However, if the undercoat layer is hard, it tends to become brittle. Therefore, when the transparent conductive film is bent at the time of production or use, cracks occur in stripes, and only the cracked portions appear white and stripes. As a result, there occurs a problem that the transparent conductive film has a poor appearance.

An object of the present invention is to provide a transparent conductive film that has good wet heat durability and can suppress appearance defects due to bending.

The present invention [1] includes a transparent resin substrate, an adhesive layer, an optical adjustment layer, and a transparent conductive layer in this order, and the optical adjustment layer has a hardness according to JIS Z 2255 of 0.5 GPa or more. The optical adjustment layer includes a transparent conductive film arranged on one side in the thickness direction of the adhesive layer so as to contact one side in the thickness direction of the adhesive layer.

The present invention [2] includes the transparent conductive film according to [1], wherein the adhesive layer has a refractive index of 1.50 or more and 1.70 or less.

The present invention [3] includes the transparent conductive film according to [1] or [2], wherein the thickness of the adhesive layer is 10 nm or more and 100 nm or less.

In the present invention [4], the adhesive layer includes the transparent conductive film according to any one of [1] to [3] including an adhesive composition containing an aromatic dicarboxylic acid ester.

The present invention [5] includes the transparent conductive film according to [4], wherein the aromatic dicarboxylic acid ester is a reaction product of an aromatic dicarboxylic acid and glycol, and the glycol contains propylene glycol. I'm out.

The present invention [6] includes the transparent conductive film according to any one of [1] to [5], in which the optical adjustment layer is made of a resin composition containing a polymer having a saturated hydrocarbon ring. There is.

According to the transparent conductive film of the present invention, the wet heat durability is good, and the poor appearance due to bending can be suppressed.

FIG. 1 shows a cross-sectional view of a transparent conductive film according to an embodiment of the present invention. FIG. 2 shows a cross-sectional view of a mode in which the transparent conductive film shown in FIG. 1 is patterned. FIG. 3 shows a schematic diagram when a wet heat durability test is performed on a transparent conductive film.

With reference to FIG. 1, the transparent conductive film 1 of one Embodiment of this invention is demonstrated.

In FIG. 1, the vertical direction of the paper is the vertical direction (thickness direction, first direction), the upper side of the paper is the upper side (one side in the thickness direction, one side in the first direction), and the lower side of the paper is the lower side (thickness direction). The other side, the other side in the first direction). In FIG. 1, the left-right direction of the paper is the left-right direction (width direction, a second direction orthogonal to the first direction), the left side of the paper is the left side (one side in the second direction), and the right side of the paper is the right side (the other side in the second direction). ). In FIG. 1, the paper thickness direction is the front-back direction (third direction orthogonal to the first direction and the second direction), the front side of the paper is the front side (one side of the third direction), and the back side of the paper is the rear side (the third direction). The other side). Specifically, it conforms to the directional arrow in each figure. The other drawings are also based on FIG. 1.

1. Transparent Conductive Film The transparent conductive film 1 has a film shape (including a sheet shape) having a predetermined thickness, extends in a predetermined direction (plane direction) orthogonal to the thickness direction, and has a flat upper surface and a flat lower surface. Have. The transparent conductive film 1 is, for example, one component such as 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, does not include an image display element such as an LCD module, and includes a transparent resin substrate 2, an adhesive layer 3, and an optical adjustment layer 4, which will be described later. It is a device that is composed of the transparent conductive layer 5 and is distributed industrially as a component and is industrially usable.

Specifically, as shown in FIG. 1, the transparent conductive film 1 includes a transparent resin substrate 2, an adhesive layer 3, an optical adjustment layer 4, and a transparent conductive layer 5 in this order. More specifically, the transparent conductive film 1 is arranged on the transparent resin base material 2, the adhesive layer 3 arranged on the upper surface of the transparent resin base material 2 (one surface in the thickness direction), and on the upper surface of the adhesive layer 3. The optical adjustment layer 4 and the transparent conductive layer 5 disposed on the upper surface of the optical adjustment layer 4. The transparent conductive film 1 preferably comprises a transparent resin substrate 2, an adhesive layer 3, an optical adjustment layer 4, and a transparent conductive layer 5.

2. Transparent Resin Base Material The transparent resin base material 2 is a transparent base material for ensuring the mechanical strength of the transparent conductive film 1. That is, the transparent resin substrate 2 supports the transparent conductive layer 5 together with the adhesive layer 3 and the optical adjustment layer 4.

The transparent resin substrate 2 is, for example, a polymer film having transparency. Examples of the material of the transparent resin substrate 2 include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate and polyethylene naphthalate, and (meth)acrylic resins such as polymethacrylate (acrylic resin and/or methacrylic resin). For example, olefin resin such as polyethylene, polypropylene, cycloolefin polymer (COP), for example, polycarbonate resin, polyether sulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, polystyrene resin, norbornene resin, etc. Is mentioned. The transparent resin substrate 2 can be used alone or in combination of two or more kinds.

From the viewpoints of transparency, wet heat durability, mechanical strength, and the like, polyester resin is preferable, and PET is more preferable.

The total light transmittance (JIS K 7375-2008) of the transparent resin substrate 2 is, for example, 80% or more, preferably 85% or more.

The thickness of the transparent resin substrate 2 is, for example, 2 μm or more, and preferably 20 μm or more, from the viewpoint of mechanical strength, scratch resistance, and dot properties when the transparent conductive film 1 is used as a touch panel film. Further, for example, it is 300 μm or less, preferably 150 μm or less. The thickness of the transparent resin substrate 2 can be measured using, for example, a micro gauge type thickness gauge.

In addition, an antiblocking layer, a hard coat layer and the like may be provided on the upper surface and/or the lower surface of the transparent resin substrate 2 if necessary.

3. Adhesive Layer The adhesive layer 3 is a layer for reducing a defective appearance that occurs when the transparent conductive film 1 is bent. It is also a layer for improving the adhesiveness between the transparent resin substrate 2 and the optical adjustment layer 4.

The adhesive layer 3 has a film shape (including a sheet shape), and is arranged, for example, on the entire upper surface of the transparent resin base material 2 so as to contact the upper surface of the transparent resin base material 2. More specifically, the adhesive layer 3 is arranged between the transparent resin base material 2 and the optical adjustment layer 4 so as to contact the upper surface of the transparent resin base material 2 and the lower surface of the optical adjustment layer 4. ..

The adhesive layer 3 is formed of an adhesive composition.

The adhesive composition contains, for example, an aromatic dicarboxylic acid ester. The aromatic dicarboxylic acid ester is a reaction product of an aromatic dicarboxylic acid and an alcohol such as glycol.

The aromatic dicarboxylic acid is preferably phthalic acid.

Examples of glycols include ethylene glycol (EG) and propylene glycol (PG). The glycol preferably contains at least propylene glycol, and more preferably has both ethylene glycol and propylene glycol, from the viewpoint of suppressing appearance failure due to bending.

The aromatic dicarboxylic acid ester is preferably a phthalic acid ester which is a reaction product of phthalic acid and glycol, and more preferably a reaction of phthalic acid and glycol, from the viewpoint of suppressing poor appearance due to bending. Products.

The adhesive composition may contain an organic component such as a (meth)acrylic acid component, an oxazoline component, a melamine component, and a glycol component, in addition to the aromatic dicarboxylic acid ester.

Further, the adhesive composition may contain an inorganic component in addition to the above organic component.

As the inorganic component, a suitable material can be selected according to the refractive index required for the adhesive layer 3, and for example, a SiOx component (such as silica), for example, a metal oxide composed of zirconium oxide, titanium oxide, zinc oxide, or the like. Examples include carbonates such as calcium carbonate. Preferred are metal oxides, more preferred are zirconium oxide and titanium oxide, and further preferred are zirconium oxide.

The refractive index of the adhesive layer 3 is, for example, 1.50 or more, preferably 1.55 or more, more preferably 1.60 or more, and, for example, 1.70 or less, preferably 1.65 or less. Is. By setting the refractive index of the adhesive layer 3 in the above range, the visibility of the wiring pattern can be further suppressed. Further, it is possible to further suppress the appearance defect due to the bending of the transparent conductive film 1. The refractive index is measured by an Abbe refractometer.

The thickness of the adhesive layer 3 is, for example, 10 nm or more, preferably 20 nm or more, more preferably 25 nm or more, and for example, 100 nm or less, preferably 80 nm or less, more preferably 70 nm or less. By setting the thickness of the adhesive layer 3 in the above range, the adhesiveness between the transparent resin substrate 2 and the optical adjustment layer 4 can be improved, and the fluctuation of the optical characteristics with these layers can be reduced to reduce the appearance. It is possible to further suppress defects. The thickness of the adhesive layer 3 can be measured using, for example, an instant multi-photometry system.

4. Optical Adjustment Layer The optical adjustment layer 4, together with the adhesive layer 3, suppresses the visibility of the wiring pattern in the transparent conductive layer 5 and, in order to ensure the excellent transparency of the transparent conductive film 1, the optical adjustment layer 4 is It is a layer for adjusting optical properties (for example, refractive index).

The optical adjustment layer 4 has a film shape (including a sheet shape), and is arranged, for example, on the entire upper surface of the adhesive layer 3 so as to contact the upper surface of the adhesive layer 3. More specifically, the optical adjustment layer 4 is arranged between the adhesive layer 3 and the transparent conductive layer 5 so as to contact the upper surface of the adhesive layer 3 and the lower surface of the transparent conductive layer 5.

The optical adjustment layer 4 is formed of an optical adjustment composition.

The optical adjustment composition may have a hardness of 0.5 GPa or more in the optical adjustment layer 4 described later, but from the viewpoint of the hardness of the optical adjustment layer 4, (1) saturated hydrocarbon ring is preferable. And a resin composition containing a polymer having (2) a polymer having an aromatic ring. More preferred is a resin composition containing a polymer having a saturated hydrocarbon ring.

The (1) polymer having a saturated hydrocarbon ring is preferably an epoxy resin.

Examples of the saturated hydrocarbon ring include a cyclohexane ring and a norbornene ring.

Examples of the monomer that constitutes the epoxy resin include a monomer having a saturated hydrocarbon ring. Specific examples thereof include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate and hydrogenated bisphenol A diglycyl ether.

Further, as a monomer constituting the epoxy resin, in addition to the monomer having a saturated hydrocarbon ring, a monomer having no saturated hydrocarbon ring may be contained. Examples of such a monomer include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, naphthalene-type diglycidyl ether, biphenyl-type diglycidyl ether, and triglycidyl isocyanurate.

The epoxy resin is preferably rubber-modified. That is, preferably, a rubber-modified epoxy resin is used.

Examples of the rubber include polybutadiene (1,2-polybutadiene, 1,4-polybutadiene, etc.), styrene-butadiene rubber, butyl rubber, polyisobutylene rubber, chloroprene rubber, nitrile rubber, acrylic rubber and the like. Preferably, polybutadiene is used.

The weight average molecular weight of the polymer having a saturated hydrocarbon ring is, for example, 1000 or more, preferably 1500 or more, and for example, 10000 or less, preferably 5000 or less. The molecular weight is measured by gel permeation chromatography (GPC) and is determined by standard polystyrene conversion value.

From the viewpoint of hardness, the resin composition containing a polymer having a saturated hydrocarbon ring preferably contains a curing agent in addition to the above polymer.

Examples of the curing agent include antimony trioxide, benzylmethyl p-methoxycarbonyloxyphenylsulfonium hexafluoroantimonate, hexafluoroantimonate, and other antimony-based curing agents, such as p-methylthiophenol and naphthol-based compounds. ..

When the optical adjustment composition contains a curing agent, the content ratio of the curing agent to 100 parts by mass of the polymer having a saturated hydrocarbon ring is, for example, 0.005 parts by mass or more, preferably 0.01 parts by mass or more. Further, for example, it is 0.5 parts by mass or less, preferably 0.1 parts by mass or less.

(2) Examples of the resin composition containing a polymer having an aromatic ring include a polyphenylene ether-based composition, an acrylic composition, and a polysiloxane-based composition.

Examples of the aromatic ring include a benzene ring and a naphthalene ring.

The polyphenylene ether-based composition contains polyphenylene ether.

Examples of the polyphenylene ether include a polymer having a phenylene ether unit represented by the following formula (1).

In the formula (1), R ^1's each independently represent a halogen atom or an optionally substituted alkyl group, phenyl group or alkoxy group. R ¹ preferably independently represents an alkyl group or a phenyl group, more preferably an alkyl group, and further preferably an alkyl group having 7 or less carbon atoms.

R ^2's each independently represent a hydrogen atom, a halogen atom, or an optionally substituted alkyl group, phenyl group or alkoxy group. R ² preferably represents a hydrogen atom.

Examples of the substituent represented by R ¹ and R ² include a halogen atom and an amino group.

Examples of the phenylene ether unit include a 2,6-dimethyl-1,4-phenylene ether unit and a 2,3,6-trimethyl-1,4-phenylene ether unit.

The polyphenylene ether may have a glycidyl ether skeleton as a main chain terminal or a side chain.

The acrylic composition contains a polymer of a monomer (acrylic polymer) whose main component is a (meth)acrylic acid ester.

The (meth)acrylic acid ester is a methacrylic acid ester and/or an acrylic acid ester, and specifically, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, ( Isopropyl methacrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, (meth)acrylic acid Hexyl, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, etc., having a linear or branched carbon number of 1 to 14( Preferable examples include (meth)acrylic acid alkyl ester having an alkyl moiety of 1 to 4).

Examples of the (meth)acrylic acid ester also include hydroxyl group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylic acid and 2-hydroxybutyl (meth)acrylic acid.

As the monomer component, in addition to the (meth)acrylic acid ester, a monomer copolymerizable with the (meth)acrylic acid ester having an aromatic ring is contained. Examples of such a monomer include alkenyl aromatic monomers such as styrene, α-methylstyrene, vinyltoluene, and divinylbenzene.

As a monomer component, in addition to the above, for example, acrylic acid, methacrylic acid, for example, α,β-ethylenically unsaturated carboxylic acid esters such as dimethyl fumarate, dibutyl fumarate and dimethyl maleate, for example, crotonic acid, maleic acid. Acids, fumaric acid and other α, β-ethylenically unsaturated carboxylic acids, for example, dienes such as 1,3-butadiene and 1,4-hexadiene, for example, olefins such as ethylene and propylene Good.

The polysiloxane composition contains a polysiloxane having an aromatic ring in its side chain.

Examples of such a polysiloxane include a reaction product obtained by hydrosilylating a siloxane having a hydrosilyl group and an organic compound having an alkenyl group.

Examples of the siloxane having a hydrosilyl group include polysiloxane having a methylhydrogensiloxane unit and a dimethylsiloxane unit, polysiloxane having a methylhydrogensiloxane unit and a methylphenylsiloxane unit, and the like.

Examples of the organic compound having an alkenyl group include aromatic hydrocarbon compounds having an alkenyl group, and specific examples thereof include divinylbenzene.

The resin composition containing a polymer having an aromatic ring may contain an isocyanate compound in addition to the above components from the viewpoint of heat resistance and expansion resistance. Examples of the isocyanate compound include hexamethylene diisocyanate, tolylene diisocyanate, bis(4-cyanatephenyl)methane, 2,2-bis(4-cyanatephenyl)propane, and allyl isocyanate. Further, cyanate resins made from these materials, trimethylolpropane adducts, isocyanurates, and the like are also included.

The optical adjustment composition may also contain particles in addition to the above components. As the particles, a suitable material can be selected according to the refractive index required for the optical adjustment layer 4, and examples thereof include inorganic particles and organic particles. Examples of the inorganic particles include silica particles, for example, metal oxide particles made of zirconium oxide, titanium oxide, zinc oxide and the like, carbonate particles such as calcium carbonate and the like. Examples of the organic particles include crosslinked acrylic resin particles.

The gelling time of the optical adjustment composition is, for example, 30 seconds or more, preferably 50 seconds or more when heated to 90° C., and, for example, 100 seconds or less, preferably 80 seconds or less. .. By setting the gelling time within the above range, the processing speed can be improved. The gelation time is, for example, by using a gelation tester, placing the optical adjustment composition on a plate whose surface temperature is set to 90° C., and measuring the time until the optical adjustment composition cures, You can ask.

The hardness of the optical adjustment layer 4 is 0.5 GPa or more. It is preferably 0.6 GPa or more, more preferably 0.7 GPa or more, and for example, 1.0 GPa or less, preferably 0.9 GPa or less. By setting the hardness of the optical adjustment layer 4 in the above range, the wet heat durability of the transparent conductive film 1 is excellent. In particular, even when left for a long time in a high-humidity and high-temperature environment, it is possible to suppress the occurrence of cracks and further suppress a large increase in the surface resistance value after the standing.

The hardness of the optical adjustment layer 4 is, for example, the hardness of the optical adjustment layer 4 when the optical adjustment layer 4 having a thickness of 30 nm is arranged on a PET film having a thickness of 50 μm, and the hardness is defined by JIS Z 2255 (2003, ultrafine). It can be measured according to the small load hardness test method).

The refractive index of the optical adjustment layer 4 is, for example, 1.20 or more, preferably 1.30 or more, and for example, 1.60 or less, preferably 1.55 or less.

The refractive index of the optical adjustment layer 4 is preferably lower than the refractive index of the adhesive layer 3, and the difference between the refractive index of the adhesive layer 3 and the refractive index of the optical adjustment layer 4 is, for example, 0.05 or more, It is preferably 0.10 or more, more preferably 0.12 or more, and for example, 0.60 or less, preferably 0.50 or less, more preferably 0.30 or less.

By setting the refractive index of the optical adjustment layer 4 in the above range, the visibility of the wiring pattern can be further suppressed. Further, it is possible to further suppress the appearance defect due to the bending of the transparent conductive film 1.

The thickness of the optical adjustment layer 4 is, for example, 1 nm or more, preferably 5 nm or more, more preferably 20 nm or more, and for example, 100 nm or less, preferably 50 nm or less, more preferably 40 nm or less. The thickness of the optical adjustment layer 4 can be measured using, for example, an instant multi-photometry system.

The ratio of the thickness of the optical adjustment layer 4 to the thickness of the adhesive layer 3 (optical adjustment layer 4/adhesive layer 3) is, for example, 0.7 or more, preferably 0.8 or more, and, for example, 1. It is 1 or less, preferably 1.0 or less.

5. Transparent Conductive Layer The transparent conductive layer 5 is a conductive layer for forming a pattern portion 7 by forming it on a wiring pattern in a later step.

The transparent conductive layer 5 is the uppermost layer of the transparent conductive film 1, has a film shape (including a sheet shape), and contacts the entire upper surface of the optical adjustment layer 4 with the upper surface of the optical adjustment layer 4. So that they are arranged.

The material of the transparent conductive layer 5 is, for example, at least one selected from the group consisting of In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, and W. The metal oxide containing the metal of is mentioned. The metal oxide may be further doped with a metal atom shown in the above group, if necessary.

Examples of the material of the transparent conductive layer 5 include indium-containing oxides such as indium tin composite oxide (ITO), antimony-containing oxides such as antimony tin composite oxide (ATO), and preferably indium. A contained oxide, more preferably ITO is mentioned.

When ITO is used as the material of the transparent conductive layer 5, the tin oxide (SnO ₂ ) content is, for example, 0.5% by mass or more, preferably the total amount of tin oxide and indium oxide (In ₂ O ₃ ). Is 3% by mass or more, and is, for example, 15% by mass or less, preferably 13% by mass or less. By setting the content of tin oxide to the above lower limit or more, the durability of the ITO layer can be further improved. By setting the content of tin oxide to the upper limit or less, crystal conversion of the ITO layer can be facilitated and stability of transparency and surface resistance can be improved.

The “ITO” in the present specification may be a 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, Fe. , Pb, Ni, Nb, Cr, Ga and the like.

The refractive index of the transparent conductive layer 5 is, for example, 1.85 or more, preferably 1.95 or more, and for example, 2.20 or less, preferably 2.10 or less.

The thickness of the transparent conductive layer 5 is, for example, 10 nm or more, preferably 15 nm or more, and for example, 30 nm or less, preferably 25 nm or less. The thickness of the transparent conductive layer 5 can be measured using, for example, an instant multi-photometry system.

The transparent conductive layer 5 may be either crystalline or amorphous, or may be a mixture of crystalline and amorphous. The transparent conductive layer 5 is preferably made of a crystalline material, and more specifically, a crystalline ITO layer. Thereby, the transparency of the transparent conductive layer 5 can be improved, and the surface resistance of the transparent conductive layer 5 can be further reduced.

When the transparent conductive layer 5 is a crystalline film, for example, when the transparent conductive layer 5 is an ITO layer, the transparent conductive layer 5 is immersed in hydrochloric acid (concentration: 5% by mass) at 20° C. for 15 minutes, washed with water, and dried to 15 mm. It can be judged by measuring the terminal resistance between the degrees. In the present specification, when the resistance between terminals is 15 kΩ or less after immersion in hydrochloric acid (20° C., concentration: 5% by mass), washing with water, and drying, the ITO layer is assumed to be crystalline.

6. Method for Manufacturing Transparent Conductive Film Next, a method for manufacturing the transparent conductive film 1 will be described.

To manufacture the transparent conductive film 1, for example, the adhesive layer 3, the optical adjustment layer 4, and the transparent conductive layer 5 are provided in this order on one surface of the transparent resin substrate 2. That is, the adhesive layer 3 is provided on the upper surface of the transparent resin substrate 2, then the optical adjustment layer 4 is provided on the upper surface of the adhesive layer 3, and then the transparent conductive layer 5 is provided on the upper surface of the optical adjustment layer 4. The details will be described below.

First, a known or commercially available transparent resin substrate 2 is prepared.

Then, if necessary, from the viewpoint of the adhesion between the transparent resin substrate 2 and the adhesive layer 3, the surface of the transparent resin substrate 2 is, for example, sputtered, corona discharge, flame, ultraviolet ray irradiation, electron beam irradiation, chemical conversion. Etching treatment such as oxidation or undercoating treatment can be performed. Further, the transparent resin base material 2 can be removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like.

Next, the adhesive layer 3 is provided on the upper surface of the transparent resin substrate 2. For example, the adhesive layer 3 is formed on the upper surface of the transparent resin substrate 2 by wet-coating the adhesive composition on the upper surface of the transparent resin substrate 2.

Specifically, for example, a liquid adhesive composition is prepared, and subsequently, the adhesive composition is applied to the upper surface of the transparent resin substrate 2 and dried.

The coating method can be appropriately selected depending on the transparent substrate. Examples thereof include a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method and an extrusion coating method.

The drying temperature is, for example, 50° C. or higher, preferably 60° C. or higher, more preferably 70° C. or higher, for example, 200° C. or lower, preferably 150° C. or lower, more preferably 100° C. or lower.

The drying time is, for example, 0.5 minutes or more, preferably 1 minute or more, and for example, 60 minutes or less, preferably 20 minutes or less.

By the above-mentioned application and drying, the adhesive composition is formed into a film shape on the upper surface of the transparent resin substrate 2.

Next, the optical adjustment layer 4 is provided on the upper surface of the adhesive layer 3. For example, the optical adjustment composition is wet-coated on the upper surface of the adhesive layer 3 to form the optical adjustment layer 4 on the upper surface of the adhesive layer 3.

Specifically, for example, a diluting solution (varnish) is prepared by diluting the optical adjustment composition with a solvent, if necessary, and then the diluting solution is applied on the upper surface of the adhesive layer 3 and the diluting solution is dried. ..

Examples of the solvent include organic solvents and water-based solvents (specifically, water), and preferably organic solvents. Examples of the organic solvent include alcohol compounds such as methanol, ethanol and isopropyl alcohol, ketone compounds such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester compounds such as ethyl acetate and butyl acetate, and propylene glycol monomethyl ether (PGME). ) And other ether compounds, for example, aromatic compounds such as toluene and xylene. These solvents can be used alone or in combination of two or more. Preferably, a ketone compound is used.

The solid content concentration in the diluent is, for example, 1% by mass or more, preferably 10% by mass or more, and for example, 30% by mass or less, preferably 20% by mass or less.

The conditions such as preparation, coating and drying of the optical adjustment composition are the same as those exemplified for the adhesive composition such as preparation, coating and drying.

When the resin of the resin composition contains an active energy ray-curable resin, the active energy ray-curable resin is cured by irradiating with an active energy ray after drying the diluting liquid.

Next, the transparent conductive layer 5 is provided on the upper surface of the optical adjustment layer 4. For example, the transparent conductive layer 5 is formed on the upper surface of the optical adjustment layer 4 by a dry method.

Examples of the dry method include a vacuum vapor deposition method, a sputtering method, an ion plating method and the like. Preferable is a sputtering method. By this method, the thin transparent conductive layer 5 can be formed.

When the sputtering method is adopted, the target material may be the above-mentioned inorganic material forming the transparent conductive layer 5, and preferably ITO. The tin oxide concentration of ITO is, for example, 0.5% by mass or more, preferably 3% by mass or more, and for example, 15% by mass or less, preferably from the viewpoint of the durability and crystallization of the ITO layer. , 13 mass% or less.

Examples of the sputtering gas include an inert gas such as Ar. Further, if necessary, a reactive gas such as oxygen gas can be used together. When using a reactive gas together, the flow rate ratio of the reactive gas is not particularly limited, but is, for example, 0.1 flow% or more and 5 flow% or less with respect to the total flow rate ratio of the sputtering gas and the reactive gas.

The atmospheric pressure at the time of sputtering is, for example, 1 Pa or less, and preferably 0.1 Pa or more and 0.7 Pa or less, from the viewpoint of suppressing a decrease in sputtering rate, discharge stability, and the like.

The power source used for the sputtering method may be, for example, a DC power source, an AC power source, an MF power source, an RF power source, or a combination thereof.

Further, in order to form the transparent conductive layer 5 having a desired thickness, the target material and the sputtering conditions may be appropriately set and the sputtering may be performed a plurality of times.

Thereby, the transparent conductive film 1 is obtained.

Next, if necessary, the crystal conversion treatment is performed on the transparent conductive layer 5 of the transparent conductive film 1.

Specifically, the transparent conductive film 1 is heat-treated in the atmosphere.

The heat treatment can be performed using, for example, an infrared heater or an oven.

The heating temperature is, for example, 100° C. or higher, preferably 120° C. or higher, and for example, 200° C. or lower, preferably 160° C. or lower. By setting the heating temperature within the above range, crystal conversion can be ensured while suppressing heat damage to the transparent resin substrate 2 and impurities generated from the transparent resin substrate 2.

The heating time is appropriately determined according to the heating temperature, but is, for example, 10 minutes or more, preferably 30 minutes or more, and for example, 5 hours or less, preferably 3 hours or less.

Thereby, the transparent conductive film 1 including the crystallized transparent conductive layer 5 is obtained.

If necessary, the transparent conductive layer 5 may be formed into a wiring pattern such as a stripe pattern by a known etching method before or after the crystal conversion process, as shown in FIG.

In the etching, for example, the covering portion (masking tape or the like) is arranged on the transparent conductive layer 5 so as to correspond to the non-patterned portion 6 and the patterned portion 7, and the transparent conductive layer 5 (non-patterned portion) exposed from the covering portion is exposed. 6) is etched using an etching solution. Examples of the etching solution include acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, oxalic acid, phosphoric acid, and mixed acids thereof. Then, the covering portion is removed from the upper surface of the transparent conductive layer 5 by, for example, peeling.

Further, in the above-described manufacturing method, the adhesive layer 3, the optical adjustment layer 4, and the transparent conductive layer 5 are provided in this order on the upper surface of the transparent resin substrate 2 while the transparent resin substrate 2 is being transported by the roll-to-roll method. They may be formed, or part or all of these layers may be formed by a batch method (single wafer method).

The total thickness of the resulting transparent conductive film 1 is, for example, 2 μm or more, preferably 20 μm or more, and for example, 300 μm or less, preferably 150 μm or less.

(Action effect)
The transparent conductive film 1 includes a transparent resin substrate 2, an adhesive layer 3, an optical adjustment layer 4, and a transparent conductive layer 5 in this order, and the hardness of the optical adjustment layer 4 is 0.5 GPa or more. .. Therefore, even when used in a high temperature and high humidity environment, the performance of the transparent conductive film 1 can be suppressed from deteriorating and the durability against heat and humidity is excellent. Specifically, the generation of cracks can be suppressed even when left in an environment of 85° C. and 85% RH for a long time.

The optical adjustment layer 4 is arranged above the adhesive layer 3 so as to come into contact with the upper surface of the adhesive layer 3. Therefore, it is possible to suppress the appearance defect due to bending.

Particularly, in the conventional transparent conductive film composed of a transparent resin substrate/optical adjustment layer/transparent conductive layer, when the optical adjustment layer 4 is hardened from the viewpoint of wet heat durability, the optical adjustment layer 4 is cracked by bending. Alternatively, only the optical adjustment layer 4 remains bent without recovering the state before bending. As a result, a void (air layer) is formed between the optical adjustment layer 4 and the transparent resin substrate 2 below it, and due to the difference in refractive index between the air layer and the optical adjustment layer 4, white portions (white stripes, etc.) ) Is observed on the transparent film. On the other hand, in the transparent conductive film 1 of the present embodiment, the transparent conductive film 1 is arranged above the adhesive layer 3 so as to come into contact with the upper surface of the adhesive layer 3. Therefore, due to the bending of the transparent conductive film 1, even if the optical adjustment layer 4 is cracked or only the optical adjustment layer 4 is bent, the adhesive layer 3 is bent and deformed to the optical adjustment layer 4. Can follow. Therefore, it is possible to suppress the generation of voids (air layer) or to reduce the voids between the optical adjustment layer 4 and the adhesive layer 3 therebelow. As a result, appearance defects due to bending can be suppressed.

Further, the adhesive layer 3 is arranged on the entire upper surface of the transparent resin base material 2 so as to contact the upper surface of the transparent resin base material 2. Therefore, the generation of voids between the adhesive layer 3 and the transparent resin substrate 2 due to bending can be suppressed. As a result, it is possible to more reliably suppress the appearance defect due to bending.

The transparent conductive film 1 is provided in, for example, an optical device. Examples of the optical device include an image display device. When the transparent conductive film 1 is provided in an image display device (specifically, an image display device having an image display element such as an LCD module), the transparent conductive film 1 is used as a base material for a touch panel, for example. .. Examples of the touch panel type include various types such as an optical type, an ultrasonic type, an electrostatic capacitance type, and a resistive film type, and are particularly preferably used for an electrostatic capacitance type touch panel.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the examples and comparative examples. Further, the compounding ratios (content ratios) used in the following description, specific numerical values such as physical property values, parameters, etc. are described in the above “Modes for carrying out the invention”, and the corresponding compounding ratios ( Substitute the upper limit (value defined as "below" or "less than") or the lower limit (value defined as "greater than or equal to" "excess") such as content ratio), physical property value, parameter etc. be able to.

Example 1
An adhesive composition containing phthalic acid ester (reaction product of phthalic acid/ethylene glycol/propylene glycol), methacrylic acid, oxazoline, ethylene glycol, propylene glycol, melamine, and zirconium oxide was prepared, and a polyethylene terephthalate film (PET) having a thickness of 50 μm was prepared. By coating and drying on one surface of a transparent resin substrate composed of a film), an adhesive layer having a thickness of 35 nm was formed. The refractive index of the adhesive layer was 1.65.

Then, 10 parts by mass of a rubber-modified epoxy resin (“ADEKA FILTERA BUR-12A”, manufactured by ADEKA, weight average molecular weight 2000) and an antimony-based curing agent (“ADEKA FILTERRA BUR-12B”, manufactured by ADEKA) 0.001 An optical adjustment composition was prepared by mixing parts by mass. The gelling time at 90° C. of the optical adjustment composition was 60 seconds.

90 parts by mass of methyl isobutyl ketone was mixed with this optical adjustment composition to prepare a varnish of the optical adjustment composition. A varnish of the optical adjustment composition was applied onto the adhesive layer and then dried to form an optical adjustment layer having a thickness of 30 nm. The refractive index of the optical adjustment layer was 1.53.

Then, an ITO layer (transparent conductive layer) having a thickness of 20 nm was formed on the upper surface of the optical adjustment layer by sputtering. Specifically, an ITO target made of a sintered body of 90% by mass of indium oxide and 10% by mass of tin oxide is sputtered under a vacuum atmosphere of an atmosphere of 0.4 Pa in which an argon gas of 98% and an oxygen gas of 2% are introduced. did. The refractive index of the ITO layer was 2.00.

This produced the transparent conductive film.

Example 2
A transparent resin composed of a polyethylene terephthalate film (PET film) having a thickness of 50 μm prepared by preparing an adhesive composition containing phthalic acid ester (reactant of phthalic acid/ethylene glycol), methacrylic acid, oxazoline, ethylene glycol, melamine, and titanium oxide. By coating and drying on one surface of the base material, an adhesive layer having a thickness of 35 nm was formed. The refractive index of the adhesive layer was 1.65.

A transparent conductive film was produced in the same manner as in Example 1 except that this adhesive layer was formed.

Comparative Example 1
A transparent conductive film was produced in the same manner as in Example 1 except that the adhesive layer was not provided.

Comparative example 2
An optical adjustment composition was prepared by mixing a methoxylated methylol melamine resin, a polyester having an isophthalic acid unit, a maleic acid ester, and a silicone. 90 parts by mass of methyl isobutyl ketone was mixed with this optical adjustment composition to prepare a varnish of the optical adjustment composition. A varnish of the optical adjustment composition was applied to one surface of a transparent resin substrate made of a PET film having a thickness of 50 μm and dried to form an optical adjustment layer having a thickness of 30 nm. The refractive index of the optical adjustment layer was 1.53.

Then, in the same manner as in Example 1, an ITO layer having a thickness of 20 nm was formed on the optical adjustment layer to manufacture a transparent conductive film.

(1) Thickness The PET film was measured using a micro gauge type thickness meter (manufactured by Mitutoyo).

The adhesive layer, the optical adjustment layer, and the transparent conductive layer were calculated based on the waveform of the interference spectrum by using an instantaneous multi-photometry system (“MCPD2000”, manufactured by Otsuka Electronics Co., Ltd.).

(2) Refractive index The refractive index of each layer is specified by an Abbe refractometer (manufactured by Atago Co., Ltd.) so that the measurement light is incident on the measurement surface under the condition of 25° C. The measurement was carried out by the measuring method of.

(3) Hardness of Optical Adjustment Layer The hardness of the optical adjustment layer was measured according to JIS Z 2255 (2003, ultra-small load hardness test method).

Specifically, a hardness measurement sample was prepared in which an optical adjustment layer having a thickness of 30 nm described in Examples or Comparative Examples was provided on the upper surface of a PET film having a thickness of 50 μm. The microscopic load hardness (HTL) was measured by pressing a triangular cone indenter against the upper surface of the optical adjustment layer of these samples. The indentation depth of the indenter was 20 nm. The results are shown in Table 1.

(4) Wet-heat durability The ITO layer was crystallized by heating the transparent conductive film of each Example and each comparative example at 150 degreeC for 1 hour.

Then, a masking tape having a width of 2 mm was adhered at intervals of 10 mm, and then the ITO layer on the non-adhered portion of the masking tape was etched to form a stripe-shaped (width 10 mm) ITO layer (see FIG. 3 ). The masking tape was peeled off, and the transparent conductive film 1 was further heated at 150° C. for 30 minutes.

Next, the glass plate 9 was arranged on the ITO layer 5 of the transparent conductive film 1 with the adhesive 8 interposed (see FIG. 3 ). This transparent conductive film with a glass plate was placed in a high temperature and humidity machine (“LHL-113”, manufactured by ESPEC Corp.) and left for 240 hours in an environment of 85° C. and 85% RH (high temperature and high humidity test). Then, the adhesive 8 and the glass plate 9 were peeled off.

The surface of the transparent conductive film after the test was visually observed. The case where white spots were clearly observed was evaluated as x, and the case where white spots were hardly observed was evaluated as o. The results are shown in Table 1.

(5) Bending test According to JIS K 5600, a mandrel test (type I, mandrel diameter 16 mm or 12 mm) was carried out, and the transparent conductive films of Examples and Comparative Examples were bent at 180 degrees. The surface (appearance) of the transparent conductive film after the test was visually observed.

When both the mandrel diameters of 16 mm and 12 mm, white streaks were observed in the bent portion, the evaluation was evaluated as x. When a mandrel having a diameter of 16 mm was used, white streaks were not observed in the bent portion, but when a mandrel having a diameter of 12 mm was used, white streaks were observed. When both the mandrel diameters of 16 mm and 12 mm, no white streak was observed, it was evaluated as ◯. The results are shown in Table 1.

In addition, in the transparent conductive film of Comparative Example 1 evaluated as x, when the cross section of the white streak portion was observed by SEM, the optical adjustment layer was bent to be convex upward, and the optical adjustment layer and the PET film were bent. Generation of large voids (air layer) was observed between them.

On the other hand, in the transparent conductive films of Examples 1 and 2 which were evaluated as ◯, the cross section of the white streak portion was observed by SEM, and the optical adjustment layer was bent so as to be convex upward. However, since the adhesion layer followed the optical adjustment layer, almost no void was generated between the optical adjustment layer and the PET film.

1 Transparent Conductive Film 2 Transparent Resin Substrate 3 Adhesive Layer 4 Optical Adjustment Layer 5 Transparent Conductive Layer

Claims (5)

A transparent resin substrate, an adhesive layer, an optical adjustment layer, and a transparent conductive layer are provided in this order,
The hardness of the optical adjustment layer according to JIS Z 2255 is 0.5 GPa or more,
The optical adjustment layer is formed of a resin composition containing a rubber-modified epoxy resin, and is arranged on one side in the thickness direction of the adhesive layer so as to come into contact with one side in the thickness direction of the adhesive layer. A transparent conductive film characterized by: The transparent conductive film according to claim 1, wherein the adhesive layer has a refractive index of 1.50 or more and 1.70 or less. The transparent conductive film according to claim 1 or 2, wherein the adhesive layer has a thickness of 10 nm or more and 100 nm or less. The transparent conductive film according to claim 1, wherein the adhesive layer is made of an adhesive composition containing an aromatic dicarboxylic acid ester. The transparent conductive film according to claim 4, wherein the aromatic dicarboxylic acid ester is a reaction product of an aromatic dicarboxylic acid and glycol, and the glycol contains propylene glycol.

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