JP2023154610A - Transparent conductive film with protective film - Google Patents

Abstract

To provide a transparent conductive film with a protective film which has excellent conductivity of a transparent conductive film while the protective film can be peeled off.SOLUTION: There is provided a transparent conductive film with a protective film which comprises a protective film having a first base material and an adhesive layer disposed on at least one surface of the first base material and a transparent conductive film having a second base material and a transparent conductive layer disposed on at least one surface of the second base material, the protective film and the transparent conductive film are disposed so that the adhesive layer and the transparent conductive layer are faced each other, the acrylic acid content in 1 g of the adhesive layer is 0.01 μg/g to 0.2 μg/g, the transparent conductive layer contains metal nanowires and the rate of increase in resistance of the transparent conductive film after 14 days at an ambient temperature of 50°C is 4% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a transparent conductive film with a protective film.

Conventionally, a transparent conductive film in which a metal oxide layer such as an indium-tin composite oxide layer (ITO layer) is formed on a transparent resin film has been frequently used as a transparent conductive film used for electrodes of touch sensors, etc. There is. However, since the transparent conductive film on which the metal oxide layer is formed has insufficient flexibility, it is difficult to use it for applications that require flexibility, such as flexible displays. Therefore, in recent years, a transparent conductive film including a conductive layer containing metal nanowires has been proposed as a transparent conductive film having excellent flexibility.

In a transparent conductive film including a conductive layer containing metal nanowires, a protective film may be laminated on the conductive layer for protection. Generally, the protective film includes an adhesive layer, and may be arranged such that the adhesive layer and the transparent conductive layer face each other. At this time, an increase in resistance value may occur due to components in the adhesive layer. Further, the above-mentioned protective film is required to be removable, and is required to be able to achieve both removability and suppression of increase in resistance value.

Patent No. 3325560 Special Publication No. 2009-505358

An object of the present invention is to provide a transparent conductive film with a protective film that is removable and has excellent conductivity.

The transparent conductive film with a protective film of the present invention includes a protective film comprising a first base material, an adhesive layer disposed on at least one surface of the first base material, and a second base material. , a transparent conductive film having a transparent conductive layer disposed on at least one surface of the second base material, the protective film and the transparent conductive film comprising: is arranged so that the adhesive layer and the transparent conductive layer face each other, the acrylic acid content in 1 g of the adhesive layer is 0.01 μg/g to 0.2 μg/g, and the transparent conductive layer The transparent conductive film contains metal nanowires, and the rate of increase in resistance of the transparent conductive film after 14 days at an environmental temperature of 50° C. is 4% or less.
In one embodiment, the peel strength of the protective film against the transparent conductive film after 14 days at an environmental temperature of 50° C. immediately after laminating the protective film and the transparent conductive film, It is 0.15N or less.
In one embodiment, the metal nanowires are silver nanowires.
In one embodiment, the transparent conductive layer further includes a polymer matrix.
In one embodiment, the first base material is formed from a thermoplastic resin.
In one embodiment, the thickness of the adhesive layer is 20 μm or less.

According to an embodiment of the present invention, there is provided a transparent conductive film with a protective film that is removable and has excellent conductivity. I can do it.

1 is a schematic cross-sectional view of a transparent conductive film with a protective film according to one embodiment of the present invention.

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

A. Overall configuration of transparent conductive film with protective film FIG. 1 is a schematic cross-sectional view of a transparent conductive film with protective film according to one embodiment of the present invention. The transparent conductive film with a protective film 100 includes a protective film 10 and a transparent conductive film 20. The protective film 10 includes a first base material 11 and an adhesive layer 12 disposed on at least one surface of the first base material 11. The transparent conductive film 20 includes a second base material 21 and a transparent conductive layer 22 disposed on at least one surface of the second base material 21. The protective film 10 and the transparent conductive film 20 are arranged so that the adhesive layer 12 and the transparent conductive layer 22 face each other. Typically, the adhesive layer 12 and the transparent conductive layer 22 are placed in contact with each other. The transparent conductive layer includes metal nanowires (not shown). In this specification, the adhesive layer refers to a substance that has adhesive properties at room temperature and adheres to an adherend with light pressure. Therefore, the adhesive layer can be peeled off from the adherend, and even when peeled off, the adhesive can maintain practical adhesive strength. Typically, a protective film is laminated for the purpose of temporarily protecting a transparent conductive film.

The present invention is characterized in that the rate of increase in resistance of the transparent conductive film after 14 days at an environmental temperature of 50° C. is 4% or less. If such a transparent conductive film is used, it is possible to obtain a transparent conductive film with a protective film that can maintain excellent conductivity even though it includes a removably laminated protective film. In addition, in this specification, "resistance increase rate of a transparent conductive film after 14 days at an environmental temperature of 50° C." refers to the rate of increase in resistance of a transparent conductive film after 14 days at an environmental temperature of 50°C. Resistance value R0 (Ω/□) of the transparent conductive layer before lamination on the transparent conductive layer and transparent conductive layer after 14 days have passed at an environmental temperature of 50 ° C. immediately after lamination so that the adhesive layer and the transparent conductive layer are in contact with each other. It can be determined by measuring the resistance value R1 (Ω/□) of the layer and using the formula ((R1-R0)/R0)×100. A method for measuring the resistance value will be described later.

The resistance increase rate of the transparent conductive film after 14 days at an environmental temperature of 50° C. is preferably 3% or less, more preferably 2% or less. Within this range, the above effect becomes significant. The lower the resistance increase rate of the transparent conductive film after 14 days at an environmental temperature of 50° C., the lower the lower limit is, for example, 1% (preferably 0.8%, more preferably 0.5%, even more preferably is 0.3%).

The transparent conductive film with a protective film as described above can be obtained, for example, by controlling the content of acrylic acid in the adhesive layer to a predetermined amount or less. By adjusting the acrylic acid content in the adhesive layer, corrosion of the metal nanowires in the transparent conductive layer can be prevented, resulting in a transparent conductive film with a protective film that can maintain excellent conductivity. Obtainable.

The acrylic acid content in 1 g of the adhesive layer is 0.2 μg/g or less. Within this range, when the protective film is laminated onto the conductive film, an increase in the resistance value of the transparent conductive layer can be prevented.
In this specification, the amount of acrylic acid in the adhesive layer means the amount of acrylic acid extracted from the adhesive layer using pure water at 100° C. for 45 minutes. Details of the method for measuring the amount of acrylic acid will be described later.

Moreover, the acrylic acid content in 1 g of the adhesive layer is 0.01 μg/g or more. Within this range, it is possible to obtain a transparent conductive film with a protective film that has particularly excellent releasability of the protective film and can significantly prevent an increase in the resistance value of the transparent conductive layer. One of the major achievements of the present invention is that by setting the acrylic acid content of the adhesive layer within a specific range, it was possible to achieve both the easy releasability of the protective film and the maintenance of the conductivity of the transparent conductive film. .

The transparent conductive film with a protective film may be in the form of a product or an intermediate in the manufacturing process.

B. Protective Film As described above, the protective film includes a first base material and an adhesive layer.

The peel strength of the protective film against the transparent conductive film immediately after laminating the protective film and the transparent conductive film is preferably 0.15 N/15 mm or less, more preferably 0.01 N/15 mm to 0.14 N/ 15 mm, more preferably 0.07 N/15 mm to 0.13 N/15 mm. Within this range, a protective film suitable for protecting transparent conductive films can be obtained. The peel strength of a protective film with respect to a transparent conductive film is defined as the peel strength of a transparent conductive film with a protective film configured such that the adhesive layer of the protective film and the transparent conductive layer of the transparent conductive film face each other. It means the strength when peeling from a transparent conductive film. Peel strength was measured using a transparent conductive film with a protective film (width: 15 mm, length: 160 mm) as a sample, at a peel angle of 90°, peel speed (tensile speed): 3 mm/min, and measurement temperature: 23 ° C. be done.

The peel strength of the protective film against the transparent conductive film is preferably 0.15 N/15 mm or less after 14 days at an environmental temperature of 50 ° C. immediately after laminating the protective film and the transparent conductive film, More preferably 0.01N/15mm to 0.14N/15mm, still more preferably 0.07N/15mm to 0.13N/15mm. The transparent conductive film with a protective film of the present invention is useful in that it can exhibit excellent releasability even over time. The above protective film can be obtained, for example, by adjusting the acrylic acid content in the adhesive layer.

(First base material)
Any suitable material may be used as the material constituting the first base material. Specifically, for example, a polymer base material such as a film or a plastic base material is preferably used.

In one embodiment, the first base material is formed from a thermoplastic resin. By using a thermoplastic resin, a protective film with excellent toughness, processability, etc. can be obtained. Examples of the thermoplastic resin include polyester resins; cycloolefin resins such as polynorbornene; acrylic resins; polycarbonate resins; cellulose resins, and the like. Among these, preferred are polyester resins, cycloolefin resins, and acrylic resins, particularly preferred are polyester resins, and most preferred are polyethylene terephthalate. These resins have excellent mechanical strength, thermal stability, moisture shielding properties, and the like. In particular, transparent conductive films with protective films are often subjected to high-temperature processes, and the above resins are advantageous in that they have excellent thermal stability. The above thermoplastic resins may be used alone or in combination of two or more.

The thickness of the first base material is preferably 5 μm to 500 μm, more preferably 25 μm to 300 μm, and even more preferably 50 μm to 200 μm.

The first base material may be surface-treated. Examples of the surface treatment include corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage electric shock exposure, ionizing radiation treatment, and coating treatment with an undercoat.

(Adhesive layer)
As mentioned above, the acrylic acid content in 1 g of the adhesive layer is 0.01 μg/g to 0.2 μg/g. The amount of acrylic acid per gram of the adhesive layer is preferably 0.01 μg/g to 0.18 μg/g, more preferably 0.01 μg/g to 0.15 μg/g, even more preferably It is 0.01 μg/g to 0.15 μg/g. Within this range, the above effect becomes significant.

The acrylic acid in the adhesive layer may be, for example, the acrylic acid in the adhesive preparation composition that was not polymerized during polymerization of the base polymer constituting the adhesive. The acrylic acid content of the adhesive layer can be adjusted by the composition of the adhesive preparation composition (eg, acrylic acid content, amount of crosslinking agent), and the like.

The adhesive layer may be formed of any suitable adhesive. The adhesive includes any suitable base polymer. Examples of base polymers include (meth)acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate/vinyl chloride copolymers, modified polyolefin polymers, and epoxy polymers. , fluorine-based polymers, rubber-based polymers, and the like.

In one embodiment, the pressure-sensitive adhesive includes a (meth)acrylic polymer as a base polymer. The (meth)acrylic polymer may be a polymer (homopolymer or copolymer) using one or more types of (meth)acrylic acid alkyl esters as a monomer component. Such an adhesive can be obtained by polymerizing a monomer in a composition for preparing an adhesive containing the monomer component. The polymerization method is not particularly limited, and the polymerization can be performed by any known method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. Solution polymerization is more preferable from the viewpoint of workability and the like. Further, the obtained polymer may be any of homopolymers, random copolymers, block copolymers, etc. In the adhesive preparation composition, the content of the (meth)acrylic acid alkyl ester is preferably 70 parts by weight or more, more preferably 90 parts by weight, based on 100 parts by weight of the monomer in the adhesive preparation composition. parts by weight or more, more preferably 95 parts by weight or more.

Specific examples of the above (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, ( Isobutyl meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, (meth)acrylic acid Octyl, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, (meth)acrylate Undecyl acid, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, (meth)acrylic acid Examples include alkyl (meth)acrylates such as octadecyl, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, (meth)acrylic acid having a linear or branched alkyl group having 2 to 20 carbon atoms (more preferably 4 to 14 carbon atoms, still more preferably 6 to 14 carbon atoms, particularly preferably 6 to 9 carbon atoms) It is an alkyl ester. In one embodiment, 2-ethylhexyl (meth)acrylate is preferably used.

In one embodiment, a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 6 to 14 carbon atoms is used. If such an alkyl (meth)acrylate ester is used, a protective film with excellent easy releasability can be obtained. In the adhesive preparation composition, the content of the (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 6 to 14 carbon atoms is based on the total amount of (meth)acrylic acid alkyl ester 100 parts by weight. On the other hand, it is preferably 50 parts by weight or more, more preferably 60 parts by weight or more, still more preferably 80 parts by weight or more, and particularly preferably 90 parts by weight or more. Within this range, a protective film particularly excellent in easy releasability can be obtained.

In one embodiment, the base polymer (preferably a (meth)acrylic polymer) contains a structural unit derived from a hydroxyl group-containing monomer. Such a base polymer can be obtained by polymerizing a composition for preparing an adhesive containing an alkyl (meth)acrylic acid ester and a hydroxyl group-containing monomer as monomer components. The hydroxyl group-containing monomer may have a hydroxyl group and a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group. The hydroxyl group may be capable of reacting with an isocyanate crosslinker. Specific examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxy Butyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, [4-(hydroxymethyl)cyclohexyl ] Examples include hydroxyalkyl (meth)acrylates such as methyl acrylate.

In addition, examples of hydroxyl group-containing monomers include N-methylol acrylamide, N-methylol methacrylamide, N-(2-hydroxyethyl) acrylamide, N-(2-hydroxyethyl) methacrylamide, N-(2-hydroxypropyl) acrylamide, N- -(2-hydroxypropyl)methacrylamide, N-(1-hydroxypropyl)acrylamide, N-(1-hydroxypropyl)methacrylamide, N-(3-hydroxypropyl)acrylamide, N-(3-hydroxypropyl)methacryl Amide, N-(2-hydroxybutyl)acrylamide, N-(2-hydroxybutyl)methacrylamide, N-(3-hydroxybutyl)acrylamide, N-(3-hydroxybutyl)methacrylamide, N-(4-hydroxy butyl) acrylamide, N-hydroxyalkyl (meth)acrylamide such as N-(4-hydroxybutyl)methacrylamide; and the like.

Among these hydroxyl group-containing monomers, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred in terms of their polymerizability and reactivity with isocyanate crosslinking agents. Preferred, particularly 4-hydroxybutyl acrylate. These hydroxyl group-containing monomers may be used alone or in combination.

In the adhesive preparation composition, the content of the hydroxyl group-containing monomer is preferably 1 to 25 parts by weight, more preferably 3 parts by weight, based on 100 parts by weight of the monomer in the adhesive preparation composition. 20 parts by weight, more preferably 6 parts by weight to 17 parts by weight, particularly preferably 8 parts by weight to 15 parts by weight.

In one embodiment, the base polymer (preferably a (meth)acrylic polymer) contains a structural unit derived from a carboxyl group-containing monomer. Such a base polymer can be obtained by polymerizing a composition for preparing an adhesive containing an alkyl (meth)acrylate ester and a ruboxy group-containing monomer as monomer components. If a base polymer containing a structural unit derived from a carboxyl group-containing monomer is used, a protective film with excellent releasability can be obtained. Specific examples of carboxyl group-containing monomers include (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and the like. Among them, acrylic acid is preferably used.

In the adhesive preparation composition, the content ratio of the carboxyl group-containing monomer is preferably more than 0 parts by weight and 5 parts by weight or less, and more preferably, based on 100 parts by weight of the monomer in the adhesive preparation composition. is from 0.005 parts by weight to 2 parts by weight, more preferably from 0.01 parts by weight to 1 part by weight, particularly preferably from 0.01 parts by weight to 0.1 parts by weight. Within this range, a protective film with particularly excellent releasability can be obtained. In addition, when the carboxyl group-containing monomer is acrylic acid, by setting its content within the above range, the acrylic acid content in the adhesive layer can be adjusted preferably, and when the protective film is laminated on the conductive film. In addition, an increase in the resistance value of the transparent conductive layer can be prevented.

The above-mentioned (meth)acrylic polymer is compatible with other monomer components copolymerizable with the above-mentioned (meth)acrylic acid alkyl ester, as necessary, for the purpose of modifying cohesive force, heat resistance, crosslinkability, etc. May contain structural units. Such monomer components include, for example, acid anhydride monomers such as maleic anhydride and icotanoic anhydride; hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and (meth)acrylate. Hydroxyl group-containing monomers such as hydroxyhexyl acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl methacrylate; styrene sulfonic acid, allyl Sulfonic acid group-containing monomers such as sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl(meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid; ) Acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, and other (N-substituted)amide monomers; ) Aminoalkyl (meth)acrylate monomers such as aminoethyl acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate; Methoxyethyl (meth)acrylate, ( Alkoxyalkyl (meth)acrylate monomers such as ethoxyethyl meth)acrylate; Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; N-methylitaconimide, N - Itaconimide monomers such as ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexy itaconimide, N-lauryl itaconimide; N-(meth)acryloyloxymethylene Succinimide monomers such as succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyoctamethylene succinimide; vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone , vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, N-vinylcaprolactam, etc. Monomers: Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxy (meth)acrylate Glycol-based acrylic ester monomers such as ethylene glycol, methoxypolypropylene glycol (meth)acrylate; heterocycles such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, halogen atoms, silicon atoms, etc. Acrylic acid ester monomer having: hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate Multifunctional monomers such as (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate; isoprene, butadiene, isobutylene and vinyl ether monomers such as vinyl ether. These monomer components may be used alone or in combination of two or more.

The weight average molecular weight of the (meth)acrylic polymer is preferably 200,000 to 5,000,000, more preferably 400,000 to 2,000,000, and even more preferably 500,000 to 1,000,000. Within this range, a pressure-sensitive adhesive layer with appropriately adjusted adhesive force can be formed. The weight average molecular weight can be measured by GPC (solvent: THF).

The above-mentioned pressure-sensitive adhesive and pressure-sensitive adhesive preparation composition may contain any appropriate additives, if necessary. Examples of the additives include crosslinking agents, catalysts (e.g., catalysts with iron as the active center, platinum catalysts), tackifiers, plasticizers, pigments, dyes, fillers, anti-aging agents, conductive materials, and ultraviolet absorbers. agents, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, solvents (for example, toluene), and the like.

In one embodiment, the pressure-sensitive adhesive further includes a crosslinking agent. Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, and chelate crosslinking agents. Among them, isocyanate-based crosslinking agents are preferred.

Specific examples of the isocyanate-based crosslinking agents include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; 2,4- Aromatic isocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane / isocyanate adducts such as hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate HL"), isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate HX"); etc. Can be mentioned. The content of the isocyanate crosslinking agent can be set to any appropriate amount depending on the desired adhesive strength, and is typically 0.1 parts by weight to 30 parts by weight based on 100 parts by weight of the base polymer. It is more preferably 0.5 parts by weight to 30 parts by weight, still more preferably 3 parts by weight to 20 parts by weight, and particularly preferably 6 parts by weight to 15 parts by weight. Within this range, a preferably crosslinked adhesive layer can be formed. Moreover, the acrylic acid content in the adhesive layer can be adjusted appropriately.

The thickness of the adhesive layer is preferably 1 μm to 100 μm, more preferably 3 μm to 70 μm, even more preferably 5 μm to 40 μm, particularly preferably 5 μm to 20 μm. In one embodiment, the thickness of the adhesive layer is 20 μm or less, preferably 15 μm or less, and more preferably 10 μm or less. With such a thickness, the acrylic acid content contained in the adhesive layer can be reduced, and as a result, when the protective film is laminated to the conductive film, the increase in resistance of the transparent conductive layer can be prevented. It can be prevented.

The above-mentioned protective film can be manufactured by any suitable method. The protective film can be obtained, for example, by coating the above adhesive on the first base material. Coating methods include bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexo printing, screen printing, etc. Various methods can be adopted. Alternatively, a protective film may be formed by forming an adhesive layer on a release liner and transferring this to the first base material.

C. Transparent Conductive Film As described above, the transparent conductive film includes a transparent conductive layer and a second base material.

(transparent conductive layer)
In one embodiment, the transparent conductive layer includes metal nanowires and optionally further includes a polymer matrix. By forming a transparent conductive layer containing metal nanowires, a transparent conductive film with excellent flexibility and light transmittance can be obtained. The polymer matrix can act as an overcoat layer, ie, the metal nanowires can be protected by the polymer matrix. As a result, corrosion of the metal nanowires is prevented, and a transparent conductive film with superior durability can be obtained.

The thickness of the transparent conductive layer is preferably 10 nm to 1000 nm, more preferably 20 nm to 500 nm.

The total light transmittance of the transparent conductive layer is preferably 85% or more, more preferably 90% or more, and still more preferably 95% or more.

The sheet resistance value of the transparent conductive layer is preferably 200 Ω/□ or less, more preferably 150 Ω/□ or less, and even more preferably 100 Ω/□ or less. The lower the sheet resistance value of the transparent conductive film is, the more preferable it is, but the lower limit thereof is, for example, 1 Ω/□ (preferably 0.5 Ω/□, more preferably 0.1 Ω/□).

(metal nanowire)
A metal nanowire refers to a conductive substance that is made of metal, has a needle-like or thread-like shape, and has a diameter of nanometers. The metal nanowires may be linear or curved. If a transparent conductive layer made of metal nanowires is used, the metal nanowires form a network, and even a small amount of metal nanowires can form a good electrical conduction path, making it possible to create a transparent conductive layer with low electrical resistance. A conductive film can be obtained. Furthermore, since the metal nanowires form a mesh, openings can be formed in the gaps between the meshes, thereby making it possible to obtain a transparent conductive film with high light transmittance.

The ratio of the thickness d to the length L (aspect ratio: L/d) of the metal nanowire is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100 to 100,000. 10,000. If metal nanowires with such a large aspect ratio are used, the metal nanowires intersect well and a small amount of metal nanowires can exhibit high conductivity. As a result, a transparent conductive film with high light transmittance can be obtained. In addition, in this specification, the "thickness of a metal nanowire" means the diameter when the cross section of the metal nanowire is circular, the short axis when it is elliptical, and the thickness of the metal nanowire when the cross section is circular. If there is, it means the longest diagonal. The thickness and length of metal nanowires can be confirmed using a scanning electron microscope or a transmission electron microscope.

The thickness of the metal nanowire is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably 10 nm to 100 nm, and most preferably 10 nm to 50 nm. Within this range, a transparent conductive layer with high light transmittance can be formed.

The length of the metal nanowire is preferably 1 μm to 1000 μm, more preferably 10 μm to 500 μm, particularly preferably 10 μm to 100 μm. Within this range, a transparent conductive film with high conductivity can be obtained.

As the metal constituting the metal nanowire, any appropriate metal may be used as long as it is a conductive metal. Examples of the metal constituting the metal nanowire include silver, gold, copper, and nickel. Furthermore, materials obtained by plating these metals (for example, gold plating) may be used. Among these, from the viewpoint of conductivity, silver, copper, or gold is preferred, and silver is more preferred.

Any suitable method may be employed as the method for producing the metal nanowires. Examples include a method of reducing silver nitrate in a solution, a method of applying voltage or current to the precursor surface from the tip of a probe, drawing out metal nanowires at the tip of the probe, and continuously forming the metal nanowires. . In the method of reducing silver nitrate in a solution, silver nanowires can be synthesized by liquid phase reduction of a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone. Uniformly sized silver nanowires have been described, for example, by Xia, Y.; etal. , Chem. Mater. (2002), 14, 4736-4745, Xia, Y. etal. Mass production is possible according to the method described in , Nano letters (2003) 3(7), 955-960.

The transparent conductive layer containing the metal nanowires can be formed by applying a dispersion in which the metal nanowires are dispersed in a solvent onto the second base material, and then drying the applied layer.

Examples of the solvent include water, alcohol solvents, ketone solvents, ether solvents, hydrocarbon solvents, aromatic solvents, and the like. From the viewpoint of reducing environmental load, it is preferable to use water.

The dispersion concentration of metal nanowires in the metal nanowire dispersion is preferably 0.1% by weight to 1% by weight. Within this range, a transparent conductive layer with excellent conductivity and light transmittance can be formed.

The metal nanowire dispersion liquid may further contain any suitable additive depending on the purpose. Examples of the additive include a corrosion inhibitor that prevents corrosion of metal nanowires, a surfactant that prevents agglomeration of metal nanowires, and the like. The type, number and amount of additives used can be appropriately set depending on the purpose.

Any suitable method may be employed as a method for applying the metal nanowire dispersion. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, letterpress printing, intaglio printing, and gravure printing. Any suitable drying method (for example, natural drying, blow drying, heating drying) may be employed as a drying method for the coating layer. For example, in the case of heat drying, the drying temperature is typically 50°C to 200°C, and the drying time is typically 1 to 10 minutes.

The content of metal nanowires in the transparent conductive layer is preferably 30% to 90% by weight, more preferably 45% to 80% by weight, based on the total weight of the transparent conductive layer. Within this range, a transparent conductive film with excellent conductivity and light transmittance can be obtained.

When the metal nanowires are silver nanowires, the density of the transparent conductive layer is preferably 1.3 g/cm ³ to 10.5 g/cm ³ , more preferably 1.5 g/cm ³ to 3.0 g/cm 3 It is ³ . Within this range, a transparent conductive film with excellent conductivity and light transmittance can be obtained.

In one embodiment, the transparent conductive layer is patterned. As the patterning method, any appropriate method can be adopted depending on the form of the transparent conductive layer. The shape of the pattern of the transparent conductive layer may be any suitable shape depending on the application. Examples include patterns described in Japanese Patent Publication No. 2011-511357, Japanese Patent Application Laid-open No. 2010-164938, Japanese Patent Application Publication No. 2008-310550, Japanese Patent Application Publication No. 2003-511799, and Japanese Patent Application Publication No. 2010-541109. After the transparent conductive layer is formed on the second substrate, it can be patterned using any suitable method depending on the form of the transparent conductive layer.

In one embodiment, the metal nanowires in the transparent conductive layer have a fused network structure. Metal nanowires having a fused network structure are in a state in which metal nanowires are fused together at contact points. By forming a transparent conductive layer containing metal nanowires having a fused network structure, a transparent conductive film with higher conductivity can be obtained without impairing transparency.

The transparent conductive layer containing the metal nanowires having the above-mentioned fusion network structure can be formed, for example, by adding an additive for promoting fusion to the metal nanowire dispersion. Examples of such additives include metal halides (e.g., LiCl, CsCl, NaF, NaCl, NaBr, NaI, KCl, MgCl ₂ , CaCl ₂ , AlCl ₃ , AgF, etc.), inorganic acids (e.g., nitric acid, nitrous acid, etc.). , sulfuric acid, etc.), organic acids (e.g. oxalic acid, citric acid, formic acid, acetic acid, lactic acid, propionic acid, butyric acid, acrylic acid, pyruvic acid, trichloroacetic acid, trifluoroacetic acid, hexanoic acid, octanoic acid, decanoic acid, dodecane) (lauric) acid, tetradecanoic (myristic) acid, hexadecanoic (palmitic) acid, octadecanoic (stearic) acid, 2-ethylbutyric acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, 2-propylpentanoic acid, pivalic acid, neoheptane acids, neononanoic acid, neodecanoic acid, etc.), silver salts (e.g., silver nitrate, silver nitrite, silver lactate, silver chloride, silver sulfate, silver oxide, silver acetate, silver chlorate, silver sulfide, etc.), silver formate, silver hexanoate, silver octoate, silver decanoate, silver dodecanoate, silver tetradecanoate, silver hexadecanoate, silver octadecanoate, silver pentanoate, silver pivalate, silver neoheptanoate, silver neononanoate, silver neodecanoate, etc.), forming silver salts. Examples include compounds (hydrogen chloride, sodium chloride, etc.) containing elements (chlorine, sulfur, etc.) that can be used. Among them, metal halides are preferred, and NaCl, AgF, LiF, Nabr, or NaF are more preferred. In one embodiment, the transparent conductive layer containing metal nanowires having the above-mentioned fused network structure is obtained by applying a metal nanowire dispersion containing the above-mentioned additive and then subjecting it to heat treatment and/or pressure treatment. can be formed. The temperature of the heat treatment is, for example, 50°C to 200°C.

The transparent conductive layer containing metal nanowires having the fused network structure may be formed by exposing a coated layer of a metal nanowire dispersion to acid halide vapor. Acid halide vapors include vapors such as HCl, HBr, HI, or mixtures thereof.

Metal nanowires having a fused network structure and a method for producing the same are described in, for example, Japanese Patent Publication No. 2015-530693. The description of the publication is incorporated herein by reference.

(polymer matrix)
Any suitable polymer may be used as the polymer constituting the polymer matrix. Examples of such polymers include acrylic polymers; polyester polymers such as polyethylene terephthalate; aromatic polymers such as polystyrene, polyvinyltoluene, polyvinylxylene, polyimide, polyamide, and polyamideimide; polyurethane polymers; epoxy polymers; and polyolefin polymers. Polymers; acrylonitrile-butadiene-styrene copolymer (ABS); cellulose; silicone polymers; polyvinyl chloride; polyacetate; polynorbornene; synthetic rubber; fluorine polymers and the like. Preferably, polyfunctional compounds such as pentaerythritol triacrylate (PETA), neopentyl glycol diacrylate (NPGDA), dipentaerythritol hexaacrylate (DPHA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane triacrylate (TMPTA), etc. A curable resin (preferably an ultraviolet curable resin) composed of acrylate is used.

A transparent conductive layer containing a polymer matrix may be formed by any suitable method. For example, the polymer matrix can be formed by forming a layer of metal nanowires on the second substrate, then applying a polymer solution onto the layer, and then drying or curing the applied layer. This operation forms a transparent conductive layer in which metal nanowires are present in a polymer matrix. Alternatively, a transparent conductive layer may be formed by mixing metal nanowires and a polymer solution and applying the mixed solution.

The polymer solution contains a polymer constituting the polymer matrix or a precursor of the polymer (a monomer constituting the polymer).

The polymer solution may include a solvent. Examples of the solvent contained in the polymer solution include alcohol solvents, ketone solvents, tetrahydrofuran, hydrocarbon solvents, and aromatic solvents. Preferably the solvent is volatile. The boiling point of the solvent is preferably 200°C or lower, more preferably 150°C or lower, and still more preferably 100°C or lower.

(Second base material)
The thickness of the second base material is preferably 8 μm to 500 μm, more preferably 10 μm to 250 μm, even more preferably 10 μm to 150 μm, particularly preferably 15 μm to 100 μm.

The total light transmittance of the second base material is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. Within this range, a transparent conductive film suitable for use in a touch panel or the like can be obtained.

As the resin constituting the second base material, any suitable resin may be used as long as the effects of the present invention can be obtained. Examples of the resin constituting the second base material include cycloolefin resin, polyimide resin, polyvinylidene chloride resin, polyvinyl chloride resin, polyethylene terephthalate resin, polyethylene naphthalate resin, and the like. Preferably, it is a cycloolefin resin. If a cycloolefin resin is used, a second base material having high moisture barrier properties can be obtained at low cost.

As the cycloolefin resin, for example, polynorbornene can be preferably used. Polynorbornene refers to a (co)polymer obtained by using a norbornene monomer having a norbornene ring as part or all of the starting materials (monomers).

Various products are commercially available as the polynorbornene. Specific examples include the product names "ZEONEX" and "ZEONOR" manufactured by Nippon Zeon, the product name "Arton" manufactured by JSR, the product name "Topas" manufactured by TICONA, and the product name manufactured by Mitsui Chemicals. One example is "APEL".

The glass transition temperature of the resin constituting the second base material is preferably 50°C to 200°C, more preferably 60°C to 180°C, even more preferably 70°C to 160°C. If the second base material has a glass transition temperature within this range, deterioration during formation of the transparent conductive layer can be prevented.

The second base material may further contain any suitable additives as necessary. Examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinkers, and thickeners. etc. The type and amount of the additive used can be appropriately set depending on the purpose.

Any suitable molding method can be used to obtain the second base material, such as compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, and FRP molding. An appropriate method may be selected from among molding methods, solvent casting methods, and the like. Among these manufacturing methods, extrusion molding method or solvent casting method is preferably used. This is because the smoothness of the second base material obtained can be improved and good optical uniformity can be obtained. Molding conditions can be set as appropriate depending on the composition, type, etc. of the resin used.

If necessary, the second base material may be subjected to various surface treatments. Any appropriate method may be used for surface treatment depending on the purpose. Examples include low-pressure plasma treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, and acid or alkali treatment. In one embodiment, the second substrate is surface treated to make the second substrate surface hydrophilic.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. The method for measuring each characteristic is as follows. Note that unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight.
(1) Resistance increase rate of transparent conductive film after 14 days under an environmental temperature of 50°C Resistance value R0 (Ω/□) of the transparent conductive layer of the transparent conductive film before laminating on the protective film and the adhesive layer The resistance value R1 (Ω/□) of the transparent conductive layer was measured after 14 days had elapsed under an environmental temperature of 50° C. immediately after laminating the transparent conductive layer so as to be in contact with the transparent conductive layer.
From the obtained measurement values, the rate of increase in resistance of the transparent conductive film after 14 days at an environmental temperature of 50° C. was determined using the formula ((R1−R0)/R0)×100.
The resistance value was measured using a non-contact resistance measuring device EC-80 (manufactured by Napson).

(2) Acrylic acid content in adhesive layer A 10 cm square adhesive layer was placed in a polypropylene container and weighed. Next, 50 mL of ultrapure water (temperature: 100°C) was added to the polypropylene container. Next, the adhesive layer was left for 45 minutes in the ultrapure water maintained at 100°C to perform heating extraction. Thereafter, the solution (extract liquid) containing extracted components of the adhesive layer was filtered through a membrane filter with a pore size of 0.2 μm, and the acrylic acid ions in the filtrate were quantitatively analyzed by ion chromatography. Acrylic acid content was measured.
The measurement conditions were as follows.
・Analyzer: Thermo Fisher Scientific ICS 6000
・Separation column: Dionex Ion Pac AS18 2mm x 250mm
・Guard column: Dionex Ion Pac AG18 2mm x 50mm
・Removal system: AERS 500 (external mode)
・Detector: Electric conductivity detector ・Eluent: Potassium hydroxide aqueous solution ・Eluent flow rate: 0.25mL/min
・Sample sample injection amount: 25μL

(3) Peel strength of protective film against transparent conductive film (peel strength between adhesive layer/conductive layer) A1
Peel strength A1 (peel strength between adhesive layer/conductive layer) was measured after 14 days had passed at an environmental temperature of 50° C. immediately after laminating the adhesive layer and the transparent conductive layer so that they were in contact with each other.
Peel strength was measured using a variable angle peel measuring machine (VPA2, Kyowa Interface Science) using a transparent conductive film with a protective film (width: 15 mm, length: 160 mm) as a sample, at a peel angle of 90° and a peel speed (tensile speed). ): Measured under the condition of 3 mm/min. The value obtained by dividing the maximum load at this time (the maximum value of the load excluding the peak top at the initial stage of measurement) by the sample width was defined as the peel strength (N/15 mm width). The peel strength was measured in an atmosphere at a temperature of 23°C.

[Production Example 1] Production of transparent conductive film I A composition for forming a transparent conductive layer (PN) having a solid content concentration of 0.05% by weight was prepared by diluting with 25 parts by weight of the above silver nanowire dispersion and 75 parts by weight of pure water. Prepared.
The above composition for forming a transparent conductive layer (PN) was applied to one side of the second base material (cycloolefin film (manufactured by Nippon Zeon Co., Ltd., product name "ZEONOR (registered trademark)", thickness 55 μm), and dried. In this way, a transparent conductive layer was formed.

[Production Example 2] Production of transparent conductive film II (preparation of transparent conductive layer forming composition (PN))
A composition for forming a transparent conductive layer (PN) was prepared in the same manner as in Production Example 1.
(Preparation of monomer composition)
1 part by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat #300"), 0.2 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 907"), and 80 parts by weight of isopropyl alcohol. 1% by weight, and diluted with 19 parts by weight of diacetone alcohol to obtain a monomer composition having a solid content concentration of 1% by weight.
(Preparation of transparent conductive film)
The above composition for forming a transparent conductive layer (PN) was applied to one side of the second base material (cycloolefin film (manufactured by Nippon Zeon Co., Ltd., product name "ZEONOR (registered trademark)", thickness 55 μm), and dried. Furthermore, the above monomer composition was applied onto the transparent conductive layer forming composition (PN) coating layer, dried at 80° C. for 1 minute, and then irradiated with ultraviolet light at 450 mJ/cm ² to form the transparent conductive layer. was formed.

[Production Example 3] Preparation of Adhesive I In a four-bottle flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 100 parts by weight of 2-ethylhexyl acrylate (2EHA) and 4-hydroxybutyl acrylate (HBA) were added. 10 parts by weight of acrylic acid, 0.02 parts by weight of acrylic acid, 0.2 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 205 parts by weight of ethyl acetate, and nitrogen gas was introduced while stirring gently. Then, a polymerization reaction was carried out for about 4 hours while maintaining the liquid temperature in the flask at around 63° C. to prepare an acrylic polymer (A1) solution (about 35% by weight). The weight average molecular weight of the acrylic polymer (A1) was 600,000, and the Tg was -67°C.
The above acrylic polymer (A1) solution (about 35% by weight) was diluted to 29% by weight with ethyl acetate, and an isocyanate crosslinking agent (trimethylolpropane) was added to 100 parts by weight (solid content) of the acrylic polymer in this solution. / tolylene diisocyanate trimer adduct, manufactured by Nippon Polyurethane Industries Co., Ltd., trade name "Coronate L") 12 parts by weight, iron catalyst: tris(acetylacetonate) iron (manufactured by Nippon Kagaku Sangyo Co., Ltd., trade name "Naseem Daini") Adhesive I was prepared by adding 0.01 part by weight of "iron") and 0.69 part by weight of acetylacetone as a compound that causes keto-enol tautomerism, and mixing and stirring for about 1 minute while keeping the temperature around 25°C.

[Production Example 4] Preparation of Adhesive II In a four-bottle flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 100 parts by weight of 2-ethylhexyl acrylate (2EHA), 80 parts by weight of vinyl acetate, and acrylic acid were added. 5 parts by weight, 0.3 parts by weight of benzoyl peroxide (Nipper BW, manufactured by NOF Corporation) as a polymerization initiator, and 279 parts by weight of toluene, and nitrogen gas was introduced while stirring gently to lower the temperature of the liquid in the flask. The polymerization reaction was carried out at around 60° C. for about 7 hours to prepare an acrylic polymer (A2) solution (about 35% by weight).
The above acrylic polymer (A2) solution (approximately 35% by weight) was diluted to 18% by weight with methyl ethyl ketone, and an epoxy crosslinking agent (Mitsubishi 2 parts by weight of TETRAD-C (manufactured by Gas Kagaku Co., Ltd.) was added thereto, and the mixture was mixed and stirred for about 1 minute at a temperature around 25° C. to prepare acrylic pressure-sensitive adhesive II.

[Production Example 5] Preparation of Adhesive III In a four-loaf flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser, 90 parts by weight of butyl acrylate (BA), 10 parts by weight of acrylic acid, and as a polymerization initiator were added. 0.2 parts by weight of 2,2'-azobisisobutyronitrile and 234 parts by weight of ethyl acetate were charged, nitrogen gas was introduced while stirring gently, and the temperature of the liquid in the flask was maintained at around 63°C until about 7 A time polymerization reaction was performed to prepare an acrylic polymer (A3) solution (30% by weight). The weight average molecular weight of the acrylic polymer (A3) was 750,000, and the Tg was -45°C.
The above acrylic polymer (A3) solution (30% by weight) was diluted to 20% by weight with ethyl acetate, and an epoxy crosslinking agent (Mitsubishi 11 parts by weight of TETRAD-C (manufactured by Gas Kagaku Co., Ltd.) were added thereto, and the mixture was mixed and stirred for about 1 minute at a temperature around 25° C. to prepare an acrylic pressure-sensitive adhesive III.

[Production Example 6] Preparation of Adhesive IV Acrylic adhesive IV was prepared in the same manner as in Production Example 4, except that the adhesive layer was formed using 10 parts by weight of the epoxy crosslinking agent.

[Example 1]
Adhesive I was applied to one side of the first base material (polyethylene terephthalate base material, thickness: 125 μm), and then heated at 150° C. for 90 seconds to form an adhesive layer with a thickness of 20 μm. , a protective film was obtained.
The obtained protective film and transparent conductive film I were laminated so that the adhesive layer and the transparent conductive layer faced each other and were in contact with each other to obtain a transparent conductive film with a protective film.
The obtained transparent conductive film with a protective film was subjected to the above evaluation. The results are shown in Table 1.

[Example 2]
A transparent conductive film with a protective film was obtained in the same manner as in Example 1, except that transparent conductive film II was used instead of transparent conductive film I. The obtained transparent conductive film with a protective film was subjected to the above evaluation. The results are shown in Table 1.

[Comparative example 1]
Adhesive II was applied to one side of the first base material (polyethylene terephthalate base material, thickness: 38 μm), and then heated at 130° C. for 60 seconds to form an adhesive layer with a thickness of 5 μm. , a protective film was obtained.
The obtained protective film and transparent conductive film I were laminated so that the adhesive layer and the transparent conductive layer faced each other and were in contact with each other to obtain a transparent conductive film with a protective film.
The obtained transparent conductive film with a protective film was subjected to the above evaluation. The results are shown in Table 1.

[Comparative example 2]
Adhesive III was applied to one side of the first base material (polyethylene terephthalate base material, thickness: 125 μm), and then heated at 150° C. for 90 seconds to form an adhesive layer with a thickness of 20 μm. , a protective film was obtained.
The obtained protective film and transparent conductive film I were laminated so that the adhesive layer and the transparent conductive layer faced each other and were in contact with each other to obtain a transparent conductive film with a protective film.
The obtained transparent conductive film with a protective film was subjected to the above evaluation. The results are shown in Table 1.

[Comparative example 3]
A transparent conductive film with a protective film was obtained in the same manner as in Comparative Example 1, except that transparent conductive film II was used instead of transparent conductive film I. The obtained transparent conductive film with a protective film was subjected to the above evaluation. The results are shown in Table 1.

[Comparative example 4]
A transparent conductive film with a protective film was obtained in the same manner as in Comparative Example 2, except that transparent conductive film II was used instead of transparent conductive film I. The obtained transparent conductive film with a protective film was subjected to the above evaluation. The results are shown in Table 1.

[Comparative example 5]
Adhesive IV was applied to one side of the first base material (polyethylene terephthalate base material, thickness: 38 μm), and then heated at 130° C. for 60 seconds to form an adhesive layer with a thickness of 13 μm. , a protective film was obtained.
The obtained protective film and transparent conductive film I were laminated so that the adhesive layer and the transparent conductive layer faced each other and were in contact with each other to obtain a transparent conductive film with a protective film.
The obtained transparent conductive film with a protective film was subjected to the above evaluation. The results are shown in Table 1.

As is clear from Table 1, according to the present invention, by setting the acrylic acid content in the adhesive layer to an appropriate range, the protective film has excellent removability, and the conductivity of the transparent conductive film is improved. A transparent conductive film with an excellent protective film can be provided. On the other hand, in Comparative Examples 1 to 4, the acrylic acid content in the adhesive layer was high, and therefore the resistance of the transparent conductive film increased significantly. In addition, Comparative Example 5 is an experimental example in which the content of acrylic acid in the adhesive layer was set to be below the measurement limit (at least less than 0.01 μg/g) by changing the amount of crosslinking agent. Peelability is poor.

10 Protective film 11 First base material 12 Adhesive layer 20 Transparent conductive film 21 Second base material 22 Transparent conductive layer 100 Transparent conductive film with protective film

Claims (6)

A protective film comprising a first base material and an adhesive layer disposed on at least one surface of the first base material;
A transparent conductive film with a protective film, comprising a second base material and a transparent conductive layer disposed on at least one surface of the second base material,
The protective film and the transparent conductive film are arranged such that the adhesive layer and the transparent conductive layer face each other,
The acrylic acid content in 1 g of the adhesive layer is 0.01 μg/g to 0.2 μg/g,
the transparent conductive layer includes metal nanowires,
The rate of increase in resistance of the transparent conductive film after 14 days at an environmental temperature of 50° C. is 4% or less,
Transparent conductive film with protective film. The peel strength of the protective film with respect to the transparent conductive film is 0.15 N or less after 14 days at an environmental temperature of 50 ° C. immediately after laminating the protective film and the transparent conductive film. The transparent conductive film with a protective film according to claim 1. The transparent conductive film with a protective film according to claim 1, wherein the metal nanowires are silver nanowires. The transparent conductive film with a protective film according to claim 1, wherein the transparent conductive layer further includes a polymer matrix. The transparent conductive film with a protective film according to claim 1, wherein the first base material is formed from a thermoplastic resin. The transparent conductive film with a protective film according to claim 1, wherein the adhesive layer has a thickness of 20 μm or less.