KR102622684B1 - Overcoating composition and conductive layer manufactured using the same - Google Patents

Abstract

The present invention relates to an overcoating composition that can increase the ultraviolet ray stability of a conductive film used as a transparent electrode included in a large-area display.

Description

Overcoating composition and conductive film manufactured using the same {OVERCOATING COMPOSITION AND CONDUCTIVE LAYER MANUFACTURED USING THE SAME}

The present invention relates to an overcoating composition used to manufacture a transparent conductive film in the manufacturing process of a large-area display.

In large-area displays, a transparent conductive film (i.e., transparent electrode) that transmits light to transmit images and generates current is one of the key components. The transparent conductive film must be chemically stable, have excellent smoothness and conductivity, and have high transmittance. It is required to have. Materials for such transparent conductive films include oxides such as indium tin oxide (ITO) and fluorine-doped tin oxide, conductive polymers, and metal nanowires.

The indium tin oxide (ITO) has high transmittance and excellent conductivity, so it is most widely used in manufacturing transparent conductive films. However, indium tin oxide has a problem in that the manufacturing cost of a transparent conductive film increases due to limited reserves.

The conductive polymer is a material that can replace indium tin oxide, but the manufacturing process of a transparent conductive film using it is difficult due to its low solubility, and because the energy band gap is 3 eV or less and it is colored, there is a problem in that the transmittance of the transparent conductive film is low.

The transparent conductive film manufactured using the metal nanowire can exhibit surface resistance similar to that of the transparent conductive film made of indium tin oxide, but it is very vulnerable to ultraviolet rays and has a problem in that the surface resistance increases rapidly during use. That is, when forming a transparent conductive film with metal nanowires, a polymer compound is used as a binder material. As the polymer compound is photodissociated by ultraviolet rays, oxygen is generated, and the metal nanowire is oxidized by the generated oxygen, making it transparent. The surface resistance of the conductive film increases rapidly.

Republic of Korea Patent Publication No. 2007-0096941

The present invention seeks to provide an overcoating composition that can increase the ultraviolet ray stability of a conductive film.

Additionally, the present invention seeks to provide a conductive film including a coating layer formed from the overcoating composition.

In order to solve the above problem, the present invention includes an organometallic compound in which a metal element and a ligand are combined, and the ligand is trans-1,2-Diaminocyclohexanetetraacetic acid. , or an overcoating composition that is bis-(Aminoethyl)glycolether-N,N,N',N'-tetraacetic acid. provides.

Additionally, the present invention provides a conductive layer; and a coating layer provided on the conductive layer and formed of the overcoating composition.

Since the overcoating composition of the present invention contains an organometallic compound to which a specific ligand is bound, when a conductive film is manufactured using it, it provides a conductive film that has high stability against ultraviolet rays, can maintain low surface resistance, and can exhibit high transmittance. You can.

The present invention will be described below.

1. Overcoating composition

The overcoating composition of the present invention includes an organometallic compound.

The organometallic compound included in the overcoating composition of the present invention serves to increase the ultraviolet ray stability of the conductive film and is a complex compound in which a metal element and a ligand are combined. Here, the ligand is trans-1,2-Diaminocyclohexanetetraacetic acid (DCTA), or bis-(aminoethyl)glycol ether-N,N,N',N'- Tetraacetic acid (bis-(Aminoethyl)glycolether-N,N,N',N'-tetraacetic acid, EGTA). By using this ligand, the present invention can further increase the ultraviolet ray stability of the conductive film.

Specifically, the organometallic compound combines with oxygen radicals generated by photodissociation of a polymer compound (e.g., PET or polymer additive) included in the conductive layer, which will be described later, by ultraviolet rays, thereby forming the metal nanowire included in the conductive layer. Oxidation can be prevented. At this time, since the organometallic compound is a complex compound to which the ligand (DCTA or EGTA) is bound, it can bind to more oxygen radicals than a complex compound to which other ligands are bound, thereby reducing the oxidation of the metal nanowires included in the conductive layer. It can be controlled efficiently, which can increase the ultraviolet ray stability of the conductive film and lower the sheet resistance.

The metal element bound to the ligand is not particularly limited, but is preferably at least one selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.

The content of this organometallic compound is not particularly limited, but is preferably 0.005 to 0.1 parts by weight based on 100 parts by weight of the overcoating composition. If the content of the organometallic compound is less than 0.005 parts by weight, the ultraviolet ray stability of the conductive film may decrease, and if it exceeds 0.1 part by weight, the optical characteristics of the conductive film may decrease.

Meanwhile, the overcoating composition of the present invention may further include an acrylic resin and a photoinitiator.

The acrylic resin further included in the overcoating composition of the present invention serves to increase heat resistance, adhesion, etc. of the coating layer formed by the overcoating composition. These acrylic resins are not particularly limited as long as they are known in the art.

The content of the acrylic resin is not particularly limited, but is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the overcoating composition. If the content of the acrylic resin is less than 0.1 parts by weight, the heat resistance and adhesiveness of the coating layer may decrease, and if it exceeds 5 parts by weight, the cured density of the coating layer increases, which may decrease crack resistance and durability.

The photoinitiator further included in the overcoating composition of the present invention serves to mediate the curing reaction of the acrylic resin. This photoinitiator is not particularly limited, but includes 1-hydroxycyclohexylphenylketone, 2,4,6-trimethyl benzoyl-diphenyl phosphine oxide, 2-hydroxy-2-methyl-1-phenylpropane-1-phenone, 2-Hydroxy-2-methyl-1-phenyl-1-propanone, 1-(4-isopropylphenyl)-2-hydroxy-2-methyl-1-one, 1-[4-(2-hyde oxyethoxy)phenyl]-2-hydroxy-2-methyl-propan-1-one, 2,2-diethoxy-1-phenyl-ethanone, trimethylbenzophenone, or 4-methylbenzophenone, etc. there is.

The content of the photoinitiator is not particularly limited, but is preferably 0.1 to 1 part by weight based on 100 parts by weight of the overcoating composition. If the content of the photoinitiator is less than 0.1 part by weight, uncured overcoating composition may cause poor appearance and deterioration of physical properties of the coating layer, and if it exceeds 1 part by weight, unreacted photoinitiator may remain, resulting in cracking of the coating layer. Performance, adhesion, etc. may decrease.

Additionally, the overcoating composition of the present invention may further include a solvent that adjusts viscosity. At this time, the solvent is not particularly limited as long as it is known in the art.

In addition, the overcoating composition of the present invention may further include additives (first additives) known in the art (e.g., anti-foaming agents, dispersants, adhesion promoters, etc.) to the extent that they do not affect the physical properties.

2. conductive film

The present invention provides a conductive film including a conductive layer and a coating layer.

The conductive layer included in the conductive film of the present invention is a layer that conducts heat or electricity. This conductive layer may be formed of a composition known in the art, but when considering conductivity, it is preferably formed of a conductive composition containing metal nanowires and a binder.

The metal nanowires included in the conductive composition serve to provide conductivity to the conductive composition. These metal nanowires are not particularly limited, but are preferably at least one selected from the group consisting of silver nanowires, gold nanowires, and platinum nanowires, which have excellent conductivity and high electrical stability.

The diameter of the metal nanowire is not particularly limited, but is preferably 20 nm or less, and more preferably 10 to 20 nm. If the diameter of the metal nanowire exceeds 20 nm, a milky phenomenon may occur, which may reduce the visibility of the display to which the conductive film is applied.

The content of these metal nanowires is not particularly limited, but is preferably 0.05 to 0.2 parts by weight based on 100 parts by weight of the conductive composition. If the content of the metal nanowire is less than 0.05 parts by weight, the conductivity of the conductive composition may decrease, and if it exceeds 0.2 parts by weight, it may be used more than necessary, reducing economic efficiency .

The binder included in the conductive composition serves as a matrix that fixes the metal nanowires in a dispersed and interconnected state. This binder is not particularly limited, but is preferably a cellulose-based polymer. When the cellulose-based polymer is used as a binder, it can maintain a certain viscosity and serve as a fixing matrix within the range where the conductive film maintains high permeability .

The cellulose-based polymer is not particularly limited, but is preferably at least one selected from the group consisting of methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, nitrocellulose, and carboxymethylcellulose.

The content of this binder is not particularly limited, but is preferably 0.05 to 1 part by weight based on 100 parts by weight of the conductive composition. If the content of the binder is less than 0.05 parts by weight, the dispersion and interconnectivity of the metal nanowires may be reduced, and if it exceeds 1 part by weight, the yellow index value of the conductive film may increase and reduce the visibility of the display to which the conductive film is applied. there is .

Meanwhile, the conductive composition may further include at least one additive (second additive) selected from the group consisting of a thickener, a surface tension control agent, and an adhesion promoter in order to increase its physical properties. The content of these additives is not particularly limited, but is preferably 0.005 to 0.1 parts by weight based on 100 parts by weight of the conductive composition.

Specifically, the thickener serves to increase the coatability of the conductive composition by increasing the viscosity of the conductive composition. These thickeners may be those known in the art.

The surface tension control agent serves to increase the moldability of the conductive layer by increasing the coating properties of the conductive composition. These surface tension regulators are not particularly limited, but include fluorinated compounds (fluorinated surfactants) such as perfluoroalkyl carboxylate, perfluorinated sulfonate, perfluorinated sulfate, and perfluorinated phosphate.

The content of the surface tension regulator is not particularly limited, but is preferably 0.001 to 0.01 parts by weight based on 100 parts by weight of the conductive composition. If the content of the surface tension regulator is less than 0.001 part by weight, the surface tension of the conductive composition is high and the formability of the conductive layer may be reduced, and if it exceeds 0.01 part by weight, the bubble generation control effect of the conductive composition is reduced and economic feasibility is reduced. It can be.

The adhesion promoter serves to increase the adhesion between the substrate and the conductive layer when forming a conductive layer by coating the conductive composition on the substrate. These adhesion promoters are not particularly limited, but include epoxy resins, acrylic resins, and urethane resins.

The content of the adhesion promoter is not particularly limited, but is preferably 0.005 to 0.1 parts by weight based on 100 parts by weight of the conductive composition. If the content of the adhesion promoter is less than 0.005 parts by weight, the adhesion between the substrate and the conductive layer may decrease, and if it exceeds 0.1 part by weight, the conductive layer may act as an insulating layer and increase the sheet resistance of the conductive film.

In addition, the conductive composition may further include solvents, stabilizers, dispersants, reducing agents, wetting agents, anti-foaming agents, coupling agents, etc. known in the art to the extent that they do not affect the physical properties.

The coating layer included in the conductive film of the present invention is a layer provided on the conductive layer to increase the ultraviolet ray stability of the conductive layer. As this coating layer is formed with the above-described overcoating composition, it can prevent oxidation of the metal nanowires included in the conductive layer, thereby increasing the ultraviolet ray stability of the conductive film containing it and lowering the sheet resistance.

Meanwhile, the conductive film of the present invention may further include a base layer provided under the conductive layer. The base layer is a layer that serves as a base for the conductive film, and its components may be composed of components known in the art. Specifically, the base layer is polyimide (PI), polyethylene terephthalate (PET), polyethersulfone (PES), nylon, polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), and polycarbonate ( Transparent resin films such as PC), polyarylate (PAR), etc.; Alternatively, it may be made of a glass substrate, etc.

The method of manufacturing the conductive film of the present invention described above is not particularly limited, but after coating the above-described conductive composition on a substrate and drying it to form a conductive layer, the above-described overcoating composition is coated on the formed conductive layer, dried, and cured. It can be manufactured through a process of forming a coating layer.

The method of coating the conductive composition and the overcoating composition is not particularly limited, but includes spin coating, roll coating, bar coating, spray coating, dip coating, inkjet printing, and offset printing. , screen printing, pad printing, gravure printing, flexography printing, stencil printing, imprinting, etc.

Conditions for drying after coating the conductive composition are not particularly limited, but the drying temperature may be 100 to 120° C. and the drying time may be 3 to 10 minutes. In addition, the conditions for drying and curing after coating the overcoating composition are not particularly limited, but the drying temperature is 100 to 120 ℃, the drying time is 3 to 10 minutes, and the amount of light (ultraviolet rays) irradiation during curing is 400 to 600 mJ. You can.

The thickness of the conductive film manufactured in this way is not particularly limited, but is preferably 100 to 200 nm.

Since the conductive film according to the present invention has excellent conductivity and transparency as well as stability against ultraviolet rays, it can be applied to various electrical and electronic devices. In particular, it can be usefully applied as a transparent electrode included in a large-area display used outdoors. You can.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited by the following examples.

[ Example 1, 2 and Comparative example 1 to 3] conductive film manufacturing

a) conductive layer formation

#12 A conductive composition was coated on a PET substrate using a bar coater and dried at 120° C. for 5 minutes to form a conductive layer. At this time, the conductive composition was used as a conductive composition consisting of 0.2% by weight of silver nanowires (particle diameter: 15 nm), 0.2% by weight of hydroxypropylmethylcellulose, 0.05% by weight of a fluorine-based surface tension regulator, and the remaining amount of ionized water.

b) Formation of coating layer

The overcoating composition was coated on the formed conductive layer using a #10 bar coater and dried at 100°C for 3 minutes. Afterwards, a coating layer was formed by curing by irradiating 500 mJ of ultraviolet rays. At this time, the overcoating composition used is shown in Table 1 below.

ingredient Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 organometallic compounds Fe+DCTA 0.05 - - - - Fe+EGTA - 0.05 - - - Fe+NTA - - - - 0.05 UV stabilizer HALS - - - 0.05 - Acrylic resin NATCO company
AA-401 1.0 1.0 1.0 1.0 1.0 photoinitiator a-hydroxy ketone 0.1 0.1 0.1 0.1 0.1 menstruum IPA Bal. Bal. Bal. Bal. Bal. Total (parts by weight) 100 100 100 100 100 DCTA: trans-1,2-Diaminocyclohexanetetraacetic acid
EGTA: bis-(Aminoethyl)glycolether-N,N,N',N'-tetraacetic acid
NTA: Nitrilotriacetic acid
HALS: Hindered Amine Light Stabilizer
IPA: Isopropyl alcohol

[ Experiment example ]

The physical properties of the manufactured conductive film were evaluated by the following method, and the results are shown in Table 2 below.

1. Sheet resistance (Resistivity): Measured using a R-CHEK model RC2175 surface resistivity meter from Electronic Design To Market, Inc. (Toledo, OH).

2. Transmittance and Haze: Measured using NDH5000 from NIPPON DENSHUKU.

division Sheet resistance (ohm/sq.) Transmittance Haze Before UV irradiation After UV irradiation (480h) Sheet resistance increase rate (%) Example 1 35 57 62 89.0 1.0 Example 2 37 44 18 89.0 1.0 Comparative Example 1 29 2050 6968 89.0 1.0 Comparative Example 2 30 126 320 88.5 1.2 Comparative Example 3 36 96 166 88.9 1.1

Referring to Table 2, it can be seen that the conductive film according to the present invention has a low increase rate in sheet resistance and excellent transmittance and haze as it includes a coating layer containing an organometallic compound bound to a specific ligand (DCTA or EGTA).

Claims (14)

Contains an organometallic compound in which a metal element and a ligand are combined,
The ligand is bis-(Aminoethyl)glycolether-N,N,N',N'-tetraacetic acid,
An overcoating composition wherein the metal element is one or more selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn. delete In claim 1,
An overcoating composition further comprising an acrylic resin and a photoinitiator. In claim 1,
An overcoating composition in which the content of the organometallic compound is 0.005 to 0.1 parts by weight based on 100 parts by weight of the overcoating composition. conductive layer; and
A conductive film provided on the conductive layer and including a coating layer formed of the overcoating composition of any one of claims 1, 3, and 4 . In claim 5,
The conductive layer is a conductive film formed of a conductive composition containing metal nanowires and a binder. In claim 6,
A conductive film wherein the metal nanowire is one or more selected from the group consisting of silver nanowires, gold nanowires, and platinum nanowires. In claim 6,
A conductive film wherein the diameter of the metal nanowire is 20 nm or less. In claim 6,
A conductive film wherein the binder is a cellulose-based polymer. In claim 9,
A conductive film wherein the cellulose polymer is at least one selected from the group consisting of methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, nitrocellulose, and carboxymethylcellulose. In claim 6,
A conductive film wherein the conductive composition further includes at least one additive selected from the group consisting of a thickener, a surface tension regulator, and an adhesion promoter. In claim 11,
A conductive film wherein the surface tension control agent is a fluorine-based compound. In claim 5,
A conductive film further comprising a base layer provided under the conductive layer. In claim 5,
A conductive film that is a transparent electrode included in the display.