KR20180035570A - Method of Producing Transparent Conductive Film - Google Patents

Abstract

The present invention relates to a transparent conductive film, which softens a hard coating layer formed by a thermosetting composition to improve the durability and high permeability of the transparent conductive film and simultaneously improve the adhesive force between the metal nanowire and the substrate, And then hard curing is introduced to improve the adhesion between the conductive material and the substrate.

Description

TECHNICAL FIELD [0001] The present invention relates to a transparent conductive film,

The present invention relates to a process for producing a transparent conductive film.

Transparent conductive thin films are widely used for devices that simultaneously require both light transmission and conductivity, such as touch screen panels (TSP), image sensors, solar cells, and various displays (PDP, LCD, flexible) It is widely used material.

Indium tin oxide (ITO) has been extensively studied as a transparent electrode for a display. However, in order to manufacture a thin film of ITO, a vacuum process is basically required and thus an expensive process ratio is required. In addition, Is expected to be depleted by rare metals, and the price of raw materials itself is high. Further, when the flexible display device is bent or folded, the lifetime of the display device is shortened due to the breakage of the thin film.

In order to replace ITO, technologies using carbon nanotubes, graphenes, metal nanowires, and metal mesh grids as conductive materials for transparent conductive films are being developed.

Transparent conductive films for the replacement of ITO should ensure electrical conductivity, optical properties and environmental stability corresponding to ITO films. Among the conductive materials for replacing the ITO, metal nanowires are attracting attention as materials capable of realizing low resistance, high transparency and flexibility.

When a metal having excellent electrical conductivity has a one-dimensional structure of nanowire shape, an electrically conductive film can be produced by forming a film and forming an electrical network of these. The application to nanowires using metals with excellent electrical conductivity, such as copper, may have an electrically favorable result. Further, since the diameter is several tens nm, when the film is made into a film having excellent dispersibility of nanowires, a transmittance of 85% or more can be obtained in the visible light region. Therefore, a transparent conductive film using metal nanowires, particularly silver or copper nanowires as a conductive material, is a nano material capable of realizing low resistance and high transparency.

When a transparent conductive film is produced, a substrate coated with a hard coating is generally used to impart high durability, high transmittance, and high visibility. In addition, a surface treatment or a primer layer is introduced to improve the adhesion between the conductive material and the substrate.

In order to improve the durability and high permeability of the transparent conductive film and simultaneously improve the adhesive force between the metal nanowire and the substrate, a hard coating layer made of a thermosetting composition is soft-cured, a metal nanowire is coated, So as to improve the adhesion between the conductive material and the substrate.

According to a preferred embodiment of the present invention, there is provided a method for manufacturing a hard coat layer, comprising: S1) preparing a hard coat layer by coating a thermosetting composition on a substrate; Soft-curing the prepared hard coat layer at a temperature of 50 to 150 캜 for 5 to 15 minutes (S2); Coating the soft hardened hard coat layer with a metal nanowire solution to form a conductive layer (S3); And hard curing the conductive layer at a temperature of 50 to 150 DEG C for 20 to 60 minutes after forming the conductive layer (S4).

Wherein the thermosetting composition comprises 3 to 20% by weight of an organosilane coupling agent, 0.5 to 3% by weight of a curing agent, 5 to 15% by weight of an inorganic nanocolloidal silica sol, and 62 to 91.5% by weight of a solvent .

In the step S3, the metal nanowire solution is characterized in that the metal nanowires are dispersed in a solvent in a solid content of 0.1 to 1.5% by weight.

The metal nanowires may be at least one selected from the group consisting of silver, gold, platinum, copper, aluminum, and titanium.

The metal nanowires have an average diameter of 10 to 50 nm and an average length of 10 to 50 μm.

According to the present invention, the durability and permeability of the base material can be improved, and the adhesion between the metal nanowire and the substrate on which the hard coating layer is formed can be improved, thereby improving product quality and process characteristics.

According to an embodiment of the present invention, there is provided a method of manufacturing a hard coat layer, comprising: (S1) coating a thermosetting composition on a substrate to form a hard coat layer; Soft-curing the prepared hard coat layer at a temperature of 50 to 150 캜 for 5 to 15 minutes (S2); Coating the soft hardened hard coat layer with a metal nanowire solution to form a conductive layer (S3); And hard curing the conductive layer at a temperature of 50 to 150 DEG C for 20 to 60 minutes after forming the conductive layer (S4).

First, a thermosetting composition is coated on a substrate to prepare a hard coat layer (S1).

The substrate may be a commonly used material, for example, a silicon substrate, a glass substrate, a polymer substrate, or the like, preferably a transparent material. Examples of the transparent material include glass substrates such as single silicon, p-Si, alkali silicate glass, alkali-free glass and quartz glass, silicon substrates, polyimide, polyethersulfone, polyetheretherketone, polyethylene terephthalate , A polybutylene terephthalate, a polycarbonate, a polyacrylate, and a polyurethane.

The thermosetting composition preferably comprises 3 to 20% by weight of an organosilane coupling agent, 0.5 to 3% by weight of a curing agent, 5 to 15% by weight of an inorganic nano colloidal silica sol and 62 to 91.5% by weight of a solvent.

The organosilane coupling agent is a silane which can be cured at a relatively low temperature by a sol-gel method. The silane coupling agent is glycidoxypropyl trimethoxysilane (GPTMS), methacryloxypropyltrimethoxysilane (MPTMS), glycidoxypropyl trimethoxysilane (GPTMS), phenyl trimethoxysilane (PTMS), vinyltriethoxysilane methyltriethoxysilane (MTES), tetraethoxy orthosilicate (or silicone tetraethoxide, TEOS), tetramethoxy orthosilicate (or silicone tetramethoxide, TMOS), methyl triethoxy silane (MTES), methyl trimethoxy silane (MTMS), ethyl triethoxy silane PTES). ≪ / RTI > The content of the organosilane coupling agent is preferably 3 to 20% by weight, and when it is less than 3% by weight, it may exhibit low hardness. When the content of the organosilane coupling agent is more than 20% by weight, coating becomes impossible due to gelation.

Examples of the curing agent include amine compounds such as ethylene diamine (EDA), diethylene triamine (DETA), diethylene tetraamine, triethylene tetramine (TETA), methane diamine (MDA), N, N-diethylenediamine -DEDA), tetraethylenepentaamine (TEPA), and hexamethylenediamine may be used, but the present invention is not limited thereto. The content of the curing agent is preferably from 0.5 to 3% by weight, and if it is less than 0.5% by weight, there is a problem of uncured. If it exceeds 3% by weight, an excess amount of the curing agent may deteriorate the adhesion to the substrate.

In addition, the curing agent is contained in a molar ratio of 1: 1.5: 0.5 to 1 with the organosilane coupling agent, so that the components in the thermosetting composition can be uniformed because no unreacted components remain.

The thermosetting compositions of the present invention include nanoscale inorganic nanocolloidal silica sol to improve pencil hardness, abrasion resistance, and transmittance of the hardcoat sheet. The inorganic nano-colloidal silica sol serves to collect incident light after formation of the coating film so as not to scatter, thereby improving the transmittance of the coating film. The inorganic nano-colloidal silica sol used in the present invention preferably has a solid content of 10 to 50% by weight of silica having an average particle diameter of 3 to 50 nm, preferably 5 to 20 nm, dispersed in a solvent. The solvent is the same as the following solvent types. The inorganic nanocolloidal silica sol may be obtained commercially, for example, Ludox product of Aldrich Corp. may be used. The content of the inorganic nanocolloidal silica sol is 5 to 15% by weight, preferably 2 to 10% by weight. When the content is less than 5% by weight, the improvement of the permeability is insignificant. When the content is more than 15% by weight, .

The solvent is selected from the group consisting of water (H ₂ O) methanol, ethanol, isopropanol, n-propanol, butanol, isobutanol, ethyl cellosolve, methyl cellosolve, butyl cellosolve, butyl acetate, diacetone alcohol, Glycol isopropyl alcohol and ethylene glycol isopropyl alcohol. The content of the solvent is preferably 62 to 91.5% by weight, and when it is less than 62% by weight, gelation may occur, and 91.5 If it exceeds the weight percent, it can exhibit a low degree of curing with a low solids content.

The process of coating the above-described thermosetting composition onto a substrate may be carried out by a method selected from a commonly used spray coating, bar coating, dip coating, spin coating, slit die coating, curtain coating, gravure coating, reverse gravure coating, roll coating and impregnation Can be used.

Then, the hard coat layer is soft-cured (S2).

The soft curing process is preferably performed at a temperature of 50 to 150 ° C for 5 to 15 minutes, and the hard curing process may be partially cured by performing a soft curing process under the above conditions. When the soft curing is performed under the above conditions, when the metal nanowires are formed in a state in which the metal nanowires are not completely cured, additional curing is performed to improve the adhesion between the hard coating and the metal nanowires.

Subsequently, a metal nanowire solution is coated on the soft hardened coating layer to form a conductive layer (S3).

In the metal nanowire solution, it is preferable that the metal nanowires are dispersed in the solvent in a solid content of 0.1 to 1.5% by weight. The solvent is selected from the group consisting of water (H ₂ O) methanol, ethanol, isopropanol, n-propanol, butanol, isobutanol, ethyl cellosolve, methyl cellosolve, butyl cellosolve, butyl acetate, diacetone alcohol, Glycol isopropyl alcohol, ethylene glycol isopropyl alcohol, and the like.

If the solid content of the metal nanowires is less than 0.1 wt%, a sufficient network can not be formed after coating, resulting in no surface resistance. If the solid content is more than 1.5 wt%, a large amount of metal nanowires are formed in the solution, There is a problem that agglomeration occurs to deteriorate optical properties.

The metal nanowires may be at least one selected from the group consisting of silver, gold, platinum, copper, aluminum, and titanium.

The metal nanowires have an average diameter of 10 to 50 nm and an average length of 10 to 50 μm.

The thickness of the conductive layer is preferably 10 to 500 nm. If the thickness is more than 500 nm, the resistance is low, but the transmittance is decreased and the optical characteristics such as Hz and YI are increased. The thickness of the conductive layer is preferably 30 to 300 nm.

The process of coating the above-mentioned metal nanowire solution on the soft hardened hard coat layer may be carried out by a commonly used spray coating, bar coating, dip coating, spin coating, slit die coating, curtain coating, gravure coating, reverse gravure coating, Coating and impregnation methods may be used.

Subsequently, after the conductive layer is formed, the conductive layer is hard-cured at a temperature of 50 to 150 DEG C for 20 to 60 minutes (S4). Hard hardening may be performed under the above conditions to completely harden the hard coating layer formed in the previous step.

The method for producing a transparent conductive film according to the present invention is characterized in that a soft curing process, a conductive layer formation, and a hard curing process are sequentially performed under the above-mentioned conditions to form metal nanowires in a completely cured state, There is an effect of improving the adhesion between the hard coating and the metal nanowire without further processing.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for the purpose of illustrating the present invention more specifically, and the present invention is not limited thereto.

Example 1

First, a thermosetting composition is prepared to form a hard coat layer on a substrate.

The thermosetting composition was prepared by mixing inorganic nanocolloidal silica sol (Ludox, Sigma-Aldrich Co., Ltd.) containing 30% by weight of ethanol (EtOH) and 30% by weight of water and a silica having an average particle size of 12 nm in a solid content of 30% ) Was added thereto, followed by stirring for 1 hour. Thereafter, a certain amount of nitric acid (HNO ₃ ) was added during stirring to adjust the pH of the solution to 6. After adding GPTMS (98%, Aldrich Chemical) as an organosilane coupling agent in an amount of 9 wt% The mixture was stirred for 24 hours while maintaining the temperature at 30 占 폚. Ethylene diamine (99%, Aldrich Chemical) as a curing agent was added to the stirred solution in an amount of 1 wt% and stirred for 1 hour to prepare a final thermosetting composition.

The thermosetting composition prepared above was bar-coated on a PET substrate and soft cured at 80 ° C for 10 minutes.

Meanwhile, a metal nanowire solution was prepared to form a conductive layer.

The metal nanowire solution was prepared by adding silver nanowires having an average diameter of 10 to 40 nm and an average length of 10 to 30 占 퐉 in water to a solid content of 0.25% by weight and then staining the silver nanowires on the solvent for 30 minutes. Lt; / RTI >

The prepared metal nanowire solution was bar-coated on the hard-cured hard coating layer to form a conductive layer. Next, after the conductive layer was formed, a hard curing process was performed at a temperature of 80 ° C for 30 minutes to prepare a transparent conductive film.

Example 2

The same procedure as in Example 1 was carried out except that the time in the soft curing step was 15 minutes and the time in the hard curing step was 30 minutes.

Example 3

Was carried out in the same manner as in Example 2 except that MPTMS (97%, Esung Materials), an organosilane coupling agent, was added in an amount of 9 wt%.

Example 4

The same procedure as in Example 1 was carried out except that the temperature in the soft curing process was 100 ° C and the temperature in the hard curing process was 120 ° C.

Example 5

The same procedure as in Example 1 was carried out except that the temperature in the soft curing process was 120 ° C and the temperature in the hard curing process was 150 ° C.

Comparative Example 1

First, a metal nanowire solution is prepared. Silver nanowires having an average diameter of 10 to 40 nm and an average length of 10 to 30 占 퐉 were added to water in a solid content of 0.25% by weight and then stitched for 30 minutes. The silver nanowire-dispersed metal nanowire solution was bar coated onto a commercially available UV curable hard coating film (DCH-225, KOLON). Then, a hard curing process was performed at a temperature of 80 캜 for 30 minutes to prepare a transparent conductive film.

Comparative Example 2

The same procedure as in Example 1 was carried out except that the time in the soft curing step was 3 minutes.

Comparative Example 3

The same procedure as in Example 1 was carried out except that the time in the soft curing step was 30 minutes and the time in the hard curing step was 90 minutes.

Comparative Example 4

The same procedure as in Example 1 was carried out except that the temperature in the soft curing step was 40 占 폚.

Comparative Example 5

The same procedure as in Example 1 was carried out except that the temperature in the soft curing process was 200 ° C and the temperature in the hard curing process was 200 ° C.

Comparative Example 6

First, a thermosetting composition is prepared to form a hard coat layer on a substrate.

The thermosetting composition was prepared by mixing inorganic nanocolloidal silica sol (Ludox, Sigma-Aldrich Co., Ltd.) containing 30% by weight of ethanol (EtOH) and 30% by weight of water and a silica having an average particle size of 12 nm in a solid content of 30% ) Was added thereto, followed by stirring for 1 hour. Thereafter, a certain amount of nitric acid (HNO ₃ ) was added during stirring to adjust the pH of the solution to 6. After adding GPTMS (98%, Aldrich Chemical) as an organosilane coupling agent in an amount of 9 wt% The mixture was stirred for 24 hours while maintaining the temperature at 30 占 폚. Ethylene diamine (99%, Aldrich Chemical) as a curing agent was added to the stirred solution in an amount of 1 wt% and stirred for 1 hour to prepare a final thermosetting composition. The thermosetting composition prepared above was bar-coated on a PET substrate and soft cured at 80 ° C for 5 minutes. Then, a hard curing process was performed at a temperature of 80 캜 for 40 minutes.

The metal nanowire solution was prepared by adding silver nanowires having an average diameter of 10 to 40 nm and an average length of 10 to 30 占 퐉 in water to a solid content of 0.25% by weight and then staining the silver nanowires on the solvent for 30 minutes. Lt; / RTI >

The metal nanowire solution prepared above was bar coated on the hard cured hard coating layer to form a conductive layer and thermally cured at 100 ° C for 5 minutes to prepare a transparent conductive film.

How to measure

The properties of the transparent conductive films prepared according to Examples 1 to 5 and Comparative Examples 1 to 6 were measured by the following methods. The measured physical properties are shown in Table 1 below.

(1) Surface resistance and resistance uniformity

The surface resistance was measured at 9 points using a low resistance meter (loresta-GP MCP-T610 (Mitsuibishi Chemical Corporation)) and the average value of the surface resistance was measured. And the uniformity of the sheet resistance was calculated by using the standard deviation value.

(2) Transmittance

The transmittance was measured three times at 550 nm using a UV spectrometer (Nippon Denshoko, NDH2000), and the average value was determined. Visible light transmittance and haze were measured.

(3) Hayes

Were measured using Hazemeter (NDH2000, nippon denshoku).

(4) Surface resistance after adhesion evaluation (Ω / □)

Tape (104-MN1, 3M) was attached to the transparent conductive films obtained in the above Examples and Comparative Examples, and the surface resistance was measured ten times by using a low resistance meter (loresta-GP MCP-T610 (Mitsuibishi Chemical Corporation) And the average value of the surface resistance was measured.

division Hard coating
Exterior
(After soft curing) Surface resistance
(Ω / □) Resistance Uniformity (%) Permeability (%) Haze (%) Surface resistance after adhesion evaluation
(Ω / □) Example 1 Good 65 6 91 1.4 64 Example 2 Good 62 5 91 1.4 61 Example 3 Good 61 5 91 1.4 63 Example 4 Good 60 5 92 1.4 65 Example 5 Good 62 6 91 1.4 72 Comparative Example 1 Good 61 6 91 1.4 144 Comparative Example 2 Unformed Not measurable Not measurable Not measurable Not measurable Not measurable Comparative Example 3 Good 63 5 91 1.4 137 Comparative Example 4 Unformed Not measurable Not measurable Not measurable Not measurable Not measurable Comparative Example 5 Good 62 6 91 1.4 151 Comparative Example 6 Good 60 5 91 1.4 141

However, when the curing temperature and the curing time were shortened as in Comparative Examples 2 and 4, it was found that the hard coating It is difficult to form a conductive layer thereon. If the temperature and time of curing are excessive as in Comparative Examples 3 and 5, the hard coating is completely cured and does not affect the adhesion improvement.

Also, as in Comparative Example 6, adhesion hardening was not affected in the same manner when the hard curing was performed before the conductive formation.

Claims (5)

(S1) coating a thermosetting composition on a substrate to produce a hard coat layer;
Soft-curing the prepared hard coat layer at a temperature of 50 to 150 캜 for 5 to 15 minutes (S2);
Coating the soft hardened hard coat layer with a metal nanowire solution to form a conductive layer (S3); And
(S4) hard-curing the conductive layer at a temperature of 50 to 150 DEG C for 20 to 60 minutes after forming the conductive layer.
The method of claim 1, wherein the thermosetting composition comprises 3 to 20 wt% of an organosilane coupling agent, 0.5 to 3 wt% of a curing agent, 5 to 15 wt% of an inorganic nanocolloidal silica sol, and 62 to 91.5 wt% of a solvent Wherein the transparent conductive film is a transparent conductive film.
The method of claim 1, wherein the metal nanowire solution is dispersed in the solvent in a solid content of 0.1 to 1.5% by weight in the step S3.
The method of claim 3, wherein the metal nanowires are at least one selected from the group consisting of silver, gold, platinum, copper, aluminum, and titanium.
4. The method for manufacturing a transparent conductive film according to claim 3, wherein the metal nanowires have an average diameter of 10 to 50 nm and an average length of 10 to 50 mu m.