KR20150027336A - Transparent conductors - Google Patents

Abstract

The present invention relates to a transparent conductor and, more specifically, to the transparent conductor comprising a conductive layer laminated on a transparent support member. The conductive layer is composed of a metal nanowire, a metal chelate-based crosslinker, and a binder resin. The binder resin has at least one functional group selected from a group consisting of -OH, -NRH (R is hydrogen, aliphatic hydrogen group of C_1-C_12, or aliphatic hydrogen group of C_1-C_12 having a carbonyl group), -COOH, -CO-NRH (R is hydrogen or aliphatic hydrogen group of C_1-C_12), -SO_3H, and -PO_3H. Conductivity, transparency, and endurance of the transparent conductor can be improved simultaneously.

Description

Transparent conductors {TRANSPARENT CONDUCTORS}

The present invention relates to a transparent conductor having excellent conductivity, transparency and durability.

Transparent conductors refer to high-transmittance insulating surfaces or thin conductive films coated on substrates. Transparent conductors can be fabricated to have surface conductivity while maintaining adequate optical transparency.

These transparent conductors are widely used as transparent electrodes in flat liquid crystal displays, touch panels, electroluminescent devices, and thin film photovoltaic cells. And is widely used as anti-static layers and electromagnetic wave shielding layers.

Currently, vacuum deposited metal oxides such as indium tin oxide (ITO) are used as industry standard materials to provide transparency and electrical conductivity to dielectric surfaces such as glass and polymer membranes.

However, the metal oxide film is liable to be damaged by weak, bending, or other physical stresses, requires high deposition and annealing temperatures, and expensive processes such as vacuum deposition require special equipment.

To improve this, a transparent electroconductive film coated with a composition containing an electroconductive oxide and an electroconductive polymer is proposed (Japanese Patent Laid-Open No. 2008-95015). However, it has a disadvantage that it is difficult to obtain sufficient electric conductivity, and in particular, it is difficult to satisfy both electric conductivity and light transmittance.

Also disclosed is a method of forming a conductive layer on a support using metal nanowires and transferring the conductive layer onto another support (U.S. Patent Application Publication No. 2007-74016). However, there is a disadvantage in that it is difficult to completely transfer the adhesive used in the transfer, the adhesion between the support and the conductive layer, and the adjustment of the peelability. In addition, there is a problem in that the cost increases due to the application of the adhesive layer, the curing, the bonding between the supports, and the peeling.

An object of the present invention is to provide a transparent conductor including a conductive layer in which metal nanowires are fixed by a crosslinkable polymer resin and a crosslinking agent, and which is excellent in conductivity, transparency and durability at the same time.

In order to achieve the above object, the present invention has a C on a transparent support, metal nanowires, metal chelate-based crosslinking agent, and -OH, -NRH (R is hydrogen, an aliphatic hydrocarbon group or a group of C ₁ -C _{12 1} - aliphatic hydrocarbon group of _{C 12), -COOH, -CO-} NRH (R is at least one functional group selected from the group consisting of aliphatic hydrocarbons being hydrogen or _{C 1 -C 12), -SO 3} H or -PO ₃ H And a conductive layer made of a binder resin having the above-mentioned binder resin is laminated.

Preferably, the binder resin may be at least one selected from the group consisting of polyvinyl alcohol, polyallylamine, and polyacrylate.

The metal nanowires may be silver nanowires.

The binder resin may contain 10 to 90% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Wherein the metal chelate-based crosslinking agent comprises at least one metal cation selected from the group consisting of Al, Zn, Zr, Fe, Ti, Mg, Ca and Sn; A halogen, an alkoxide, and a carboxylic acid.

The conductive layer may further include an electrically conductive polymer layer.

The transparent conductor according to the present invention is excellent in conductivity, transparency and durability, and has high brightness when used as an electrode of an organic electroluminescent device or the like, minimizes corrosion of metal by an acid, There is an advantage.

The present invention relates to a transparent conductor having excellent conductivity, transparency and durability.

Hereinafter, the present invention will be described in detail.

The transparent conductor of the present invention is a transparent conductor comprising a metal nanowire, a metal chelating cross-linking agent and -OH, -NRH (wherein R is hydrogen, a C ₁ -C ₁₂ alicyclic hydrocarbon group having a C ₁ -C ₁₂ aliphatic hydrocarbon group or a carbonyl group, An aliphatic hydrocarbon group), -COOH, -CO-NRH (R is hydrogen or a C ₁ -C ₁₂ aliphatic hydrocarbon), -SO ₃ H or -PO ₃ H, and a binder resin having at least one functional group selected from the group consisting of Are stacked.

The transparent support may be composed of a rigid or flexible material generally used in the art. For example, it is possible to use glass, polyacrylate, polyolefin, polyvinyl chloride, fluoropolymer, polyamide, polyimide, polysulfone, silicone, glass resin, polyetheretherketone, polynorbornene, polyester, polyvinyl, acrylonite Butadiene-styrene copolymer, polycarbonate, or a mixture of these materials may be used.

The transparent support preferably has excellent surface smoothness, and the surface smoothness preferably has an arithmetic average roughness Ra of 5 nm or less and a maximum height average roughness Rz of 50 nm or less. Preferably, Ra is 2 nm or less and Rz is 30 nm or less, more preferably Ra is 1 nm or less and Rz is 20 nm or less.

The surface smoothness can be improved by laminating a primer layer such as a thermosetting resin, an ultraviolet ray hardening resin, an electron beam hardening resin, a radiation setting resin, etc. on the surface of the transparent support, or by machining such as polishing, , A corona, a surface treatment with plasma, or the like.

In general, the surface smoothness can be measured by an atomic force microscope (AFM) according to the surface preparation standard (JIS B 0601-2001).

In the present invention, a conductive layer containing a metal nanowire, a metal chelate crosslinking agent and a binder resin having an active hydrogen functional group is laminated on the transparent support layer to form a transparent conductive layer.

The active hydrogen functional group forms a three-dimensional structure by structurally stabilizing the coating layer by coordination bonding with silver nanowires, and bonding with a crosslinking agent.

The active hydrogen functional group is -OH, -NRH (R is hydrogen, an aliphatic hydrocarbon group of C ₁ -C ₁₂ aliphatic hydrocarbon group having a carbonyl group or a _{C 1 -C 12), -COOH,} -CO-NRH (R is hydrogen Or a C ₁ -C ₁₂ aliphatic hydrocarbon), -SO ₃ H, or -PO ₃ H.

The binder resin having an active hydrogen functional group may be at least one selected from the group consisting of polyvinyl alcohol, polyacrylic acid, and polyallylamine. Among these, polyarylamine-based resins are preferable because they can prevent the corrosion of the nanowires and are structurally more stable because of the strong bond between the binder resin and silver nanowires.

The binder resin may be 10 to 90% by weight based on 100% by weight of the solid content of the conductive layer after drying. When the content is less than 10% by weight, transparency and durability may be insufficient. When the content is more than 90% by weight, conductivity may be insufficient.

The metal nanowire may be formed of a metal selected from the group consisting of gold, platinum, silver, palladium, rhodium, lithium, ruthenium, osmium, iron, cobalt, copper, and tin. desirable. In consideration of electric conductivity and stability, it is preferable to use a mixture of silver and one kind of noble metal (except silver).

The metal nanowires preferably have an average length of 3 탆 or more, preferably 3 to 500 탆, more preferably 3 to 300 탆, in order to form a long electrically conductive path with one metal nanowire. The average diameter is preferably small in consideration of transparency, and is preferably large in consideration of electrical conductivity. In consideration of these factors, the present invention preferably has an average diameter of 10 to 300 nm, more preferably 30 to 200 nm.

The metal nanowires can be manufactured by a method commonly used in the art such as a liquid phase method and a vapor phase method. Silver nanowires, for example, are described in Adv. Mater., 2002, 14, 833-837; Chem.Mater., 2002, 14, 4736-4745; The gold nanowires are disclosed in Japanese Patent Laid-Open Nos. 2006-233252; Copper nanowires are disclosed in Japanese Patent Application Laid-Open No. 2002-266007; Cobalt nanowires can be produced by using, for example, Japanese Patent Application Laid-Open No. 2004-149871.

In addition, the conductive layer may further contain additives commonly used in the art. The additive may specifically include a crosslinking agent, a plasticizer, an antioxidant, a surfactant, a polymerization inhibitor, a coloring agent (fuel and pigment), a solvent, and the like.

The metal chelate crosslinking agent plays a role of restraining the deterioration of conductivity due to the bunching or dropping of silver nanowires by structurally stabilizing the coating layer by connecting the binder resin three-dimensionally.

Wherein the metal chelate crosslinking agent comprises at least one metal cation selected from the group consisting of Al, Zn, Zr, Fe, Ti, Mg, Ca and Sn; But are not limited to, compounds composed of one or more anions selected from the group consisting of halogens, alkoxides, and carboxylic acids. It is preferable to use a coordination compound having Al and Zn as cations in view of easiness and cost of double crosslinking.

Such a metal chelate crosslinking agent may be 5 to 30% by weight based on 100% by weight of the binder resin of the conductive layer. When the content is less than 5% by weight, durability may be insufficient, and when it is more than 30% by weight, flexibility may be insufficient.

Such a conductive layer can be produced by a liquid phase film forming method in which a conductive layer forming composition containing a metal nanowire, a metal chelate crosslinking agent and a binder resin having an active hydrogen functional group is applied and dried, A dip coating method, a dip coating method, a die coating method, a blade coating method, a bar coating method, a gravure coating method, a spray coating method, a doctor coating method and the like can be used. Further, a direct pattern forming method using an inkjet printing method gravure printing method, a screen printing method, or the like can be used.

In the present invention, an electrically conductive polymer layer may be further laminated on the conductive layer. The electrically conductive polymer is generally used in the art, and examples thereof include polypyrrole; Polyaniline; Polyacetylene type such as trans polyacetylene and cis-polyacetylene; Polythiophene, polyisothionaphthalene, polythienylene vinylene, poly 3-alkylthiophene, poly 3,4-ethylenedioxythiophene (poly 3, 4-ethylenedioxythiophene); Polyphenylene type materials such as poly p-phenylene, polyphenylene sulfide and polyphenylene vinylene; Polytetrafluoroethylene, polytoludine, polyazine, polyacene, polyfuran, polyazulene, and the like. In consideration of electrical conductivity and transparency, polyethylene dioxythiophene, polyaniline and the like are preferable.

The transparent conductor prepared by the above method has excellent conductivity, transparency and durability, and can be used as a transparent electrode.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example  One

40 parts by weight of silver nanowire, 10 parts by weight of a metal chelate crosslinking agent (aluminum citrate, Aldrich) and 10 parts by weight of a polyallylamine-based resin (Nitobo, PAA03) was spin-coated to form a conductive layer. The conductive layer was then laminated by heating at 120 DEG C for 30 minutes to spin coat the silver nanowire to a concentration of 0.005 g / m < 2 & . At this time, the polyallylamine resin was contained in an amount of 50% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  2

A transparent conductor was produced in the same manner as in Example 1 except that a polyvinyl alcohol resin (product of Nippon Synthetic Chemical Industry Co., Ltd., P2000) was used in place of the polyallylamine resin. At this time, the polyvinyl alcohol resin was contained in an amount of 50% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  3

A transparent conductor was prepared in the same manner as in Example 1 except that a polyacrylic acid resin (Aldrich, molecular weight 1800) was used in place of the polyallylamine resin. At this time, the polyacrylic acid resin was contained in an amount of 50% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  4

25 parts by weight of a polyallylamine resin (product of NITO BOSA, PAA03) and 25 parts by weight of a polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., P2000) were used in the same manner as in Example 1, . At this time, the polyallylamine and the polyvinyl alcohol resin were contained in an amount of 50 wt% based on 100 wt% of the solid content of the conductive layer after the drying.

Example  5

A transparent conductor was prepared in the same manner as in Example 1 except that zinc acetate [Zn (OAc) ₂ ] crosslinking agent was used instead of aluminum citrate. At this time, the polyallylamine-based resin was contained in an amount of 50% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  6

A transparent conductor was prepared in the same manner as in Example 1, except that instead of aluminum citrate, iron oxalate crosslinking agent was used. At this time, the polyallylamine resin was contained in an amount of 50% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  7

A transparent conductor was prepared in the same manner as in Example 1 except that zirconium acetate [Zr acetate] crosslinking agent was used instead of aluminum citrate. At this time, the polyallylamine resin was contained in an amount of 50% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  8

Except that 20 parts by weight of silver nanowire, 10 parts by weight of a metal chelate crosslinking agent (aluminum citrate, Aldrich) and 70 parts by weight of a polyallylamine resin (product of Nitto Bosch Co., PAA03) A transparent conductor was prepared using the conductive layer forming composition. At this time, the polyallyl alcohol resin was contained in an amount of 70% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  9

Except that 10 parts by weight of silver nanowire, 10 parts by weight of a metal chelate crosslinking agent (aluminum citrate, Aldrich) and 80 parts by weight of a polyallylamine resin (product of Nitto Bosch Co., PAA03) A transparent conductor was prepared using the conductive layer forming composition. At this time, the polyallyl alcohol resin was contained in an amount of 80% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  10

A conductive layer containing 70 parts by weight of silver nanowire, 5 parts by weight of a metal chelate crosslinking agent (aluminum citrate, Aldrich), and 25 parts by weight of a polyallylamine resin (manufactured by Nitto Bosch Co., PAA03) was formed in the same manner as in Example 1 A transparent conductor was prepared using the composition. At this time, the polyallyl alcohol resin was contained in an amount of 25% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  11

A conductive layer containing 95 parts by weight of silver nanowire, 1 part by weight of a metal chelate crosslinking agent (aluminum citrate, Aldrich), and 4 parts by weight of a polyallylamine resin (product of Nitto Bosch Co., PAA03) was formed in the same manner as in Example 1 A transparent conductor was prepared using the composition. At this time, the polyallylamine resin was contained in an amount of 4% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Example  12

40 parts by weight of silver nanowire, 10 parts by weight of a metal chelate crosslinking agent (aluminum citrate, Aldrich), and 100 parts by weight of a polysulfonic acid resin ( Aldrich Co., polyvinylsulfonic acid) was spin-coated to form a conductive layer. The conductive layer was then laminated by heating at 120 DEG C for 30 minutes to spin coat the silver nanowire to 0.005 g / m < 2 > Conductor. At this time, polysulfone acid storage was contained in an amount of 50% by weight based on 100% by weight of the solid content of the conductive layer after drying.

Comparative Example  One

A transparent conductor was prepared in the same manner as in Example 1 except that a methyl cellulose resin was used instead of the polyallylamine resin.

Comparative Example  2

A transparent conductor was prepared in the same manner as in Example 1 except that a polypyrrolidone resin was used in place of the polyallylamine resin.

Comparative Example  3

A transparent conductor was prepared in the same manner as in Example 1 except that polytrimethylammonium ethyl acrylate resin was used instead of polyallylamine resin.

Test Example

The properties of the transparent electrode prepared in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1 below.

1. Transparency

The transmittance at a wavelength of 500 nm was measured using a UV-3100PC instrument manufactured by Shimadzu Corporation.

<Evaluation method>

Transmittance 90% or more: ○

Transmittance less than 90%: x

2. Conductivity

The surface resistance of the conductive coating film was measured by a four-terminal method using Loresta GP TCP-T250 (manufactured by Mitsubishi Chemical Corporation), and the conductivity was calculated from the obtained surface resistance value and film thickness by the following formula .

[Equation 1]

Conductivity (S / cm) = 1 / {film thickness (cm) x surface resistance (? /?)}

<Evaluation method>

Conductivity 100 (S / cm) or more: ○

Conductivity 50 (S / cm) to less than 100 (S / cm):?

Conductivity Less than 50 (S / cm): x

3. Durability

The conductive coating film in which the surface resistance was measured in the &quot; Measurement of Conductivity of Coating Film &quot; was continuously heated in a constant temperature drier at 125 DEG C for 240 hours. After heating, the mixture was allowed to cool to room temperature, and the surface resistance value after heating was measured by the above-mentioned method to calculate the conductivity. The durability was calculated from the retention of conductivity before and after the heat resistance test.

<Evaluation method>

Conductivity retention rate 90% or more: ○

Conductivity retention rate: 70% or more and less than 90%: △

Conductivity retention rate less than 70%: x

division Transparency conductivity durability Example 1 ○ ○ ○ Example 2 ○ ○ △ Example 3 ○ ○ △ Example 4 ○ ○ ○ Example 5 ○ ○ ○ Example 6 △ ○ ○ Example 7 ○ ○ ○ Example 8 ○ △ ○ Example 9 ○ △ ○ Example 10 △ ○ ○ Example 11 △ ○ △ Implementation 12 △ △ ○ Comparative Example 1 ○ ○ × Comparative Example 2 ○ ○ × Comparative Example 3 ○ ○ ×

As shown in Table 1, the transparent conductors of Examples 1 to 12 in which a conductive layer made of a binder resin having a metal nanowire, a metal chelate crosslinking agent and an active hydrogen functional group were laminated on a transparent support according to the present invention, It was confirmed that transparency, conductivity, and durability were both superior to those of Examples 1 to 3.

Claims (6)

On the transparent support,
Metal nanowires, metal chelate-based crosslinking agent, and -OH, -NRH (R is hydrogen, an aliphatic hydrocarbon group of C ₁ -C ₁₂ aliphatic hydrocarbon group having a carbonyl group or a _{C 1 -C 12), -COOH,} -CO-NRH (Wherein R is hydrogen or a C ₁ -C ₁₂ aliphatic hydrocarbon), -SO ₃ H, or -PO ₃ H, is laminated on the transparent conductor.
The transparent conductor according to claim 1, wherein the binder resin is at least one selected from the group consisting of polyvinyl alcohol-based, polyallylamine-based, and polyacrylic acid-based resins.
The transparent conductor according to claim 1, wherein the metal nanowire is a silver nanowire.
The transparent conductor according to claim 1, wherein the binder resin contains 10 to 90% by weight based on 100% by weight of the solid content of the conductive layer after drying.
[4] The method of claim 1, wherein the metal chelate is at least one metal cation selected from the group consisting of Al, Zn, Zr, Fe, Ti, Mg, Ca and Sn; Wherein the compound is a compound comprising at least one anion selected from the group consisting of a halogen, an alkoxide, and a carboxylic acid.
The transparent conductor according to claim 1, wherein the conductive layer is further laminated with an electrically conductive polymer layer.