KR20100043755A - Primer composition for carbon nanotube conductive film and carbon nanotube conductive film with the same - Google Patents

Abstract

PURPOSE: A primer composition for a carbon nanotube conductive film is provided to ensure excellent adhesion stability between a substrate and a carbon nanotube, and to improve heat resistance and moisture resistance. CONSTITUTION: A primer composition for a carbon nanotube conductive film comprises a solution consisting of a urethane-based main material and a silicide-based side material. The solvent of the primer is water. 5-75% thermoplastic polyurethane is included per the primer. A carbon nanotube conductive film(100) comprises a substrate(10), a binder layer(20) which is coated on the substrate and comprises a urethane-based main material and a silicide-based side material, and a transparent conductive layer(30) containing carbon nanotubes.

Description

Primer composition for carbon nanotube conductive film and carbon nanotube conductive film having same {Primer composition for carbon nanotube conductive film and carbon nanotube conductive film with the same}

The present invention relates to a primer composition for a carbon nanotube conductive film and a carbon nanotube conductive film having the same, and more particularly, to improve adhesion stability to a substrate to be coated when preparing a carbon nanotube transparent conductive film, The present invention relates to a primer composition for a carbon nanotube conductive film which improves heat resistance and moisture resistance, and a carbon nanotube conductive film having the same.

In general, carbon nanotubes (CNT) form a tube in which one carbon is combined with another carbon atom in a hexagonal honeycomb pattern to form a tube, and the diameter of the tube is extremely small, such as nanometers (nm), so that the specific electrochemical Characteristics.

The carbon nanotubes have excellent mechanical, electrical, and excellent field emission characteristics. In addition, since the shape of the semiconductor has the characteristics of the semiconductor and the energy gap varies depending on the diameter, it is attracting attention in the electronics, biotechnology, and medicine. In addition, the electrical properties of carbon nanotubes are so dramatic that they are not comparable to other materials currently known.

When the carbon nanotubes are formed in a thin conductive film on a plastic or glass substrate, they can be used as transparent electrodes because they exhibit high transmittance and conductivity in the visible light region. Accordingly, carbon nanotube conductive film is an alternative to ITO (Indium Tin Oxide) transparent electrode, which is currently used as a transparent electrode such as a field emission display (FED), a flat panel display (FPD), and a touch panel. I am attracting attention.

In particular, the carbon nanotube conductive film coated on the plastic substrate is attracting attention as a next-generation display because it has a merit that the electrical property does not change even when the film is folded or bent because it is stable to external impact or stress, compared to the metal oxide thin film ITO transparent electrode. It is being researched as a transparent electrode for flexible display.

The carbon nanotube conductive film should satisfy the high transparency and flexibility while having excellent adhesion stability. However, the conventional carbon nanotube conductive film has poor adhesion stability between the substrate and the carbon nanotubes.

In addition, the carbon nanotube conductive film should have a small change rate of the sheet resistance in a weak environment of high temperature and high humidity. However, the conventional carbon nanotubes were unstable, such as a rapid change in sheet resistance in a specific environment for high temperature and high humidity. Such instability has become a major cause of lowering the reliability as a transparent electrode.

The present invention was created in order to solve the conventional problems as described above, to improve the adhesion stability between the substrate and the carbon nanotubes and to improve the heat resistance and moisture resistance, a physical and electrical very stable primer for carbon nanotube conductive film Its purpose is to provide a composition and a carbon nanotube conductive film having the same.

In order to achieve the above object, the present invention provides a primer composition for a carbon nanotube conductive film made of a solution containing a urethane-based address material and a silicon compound-based sub-material.

In this case, the solvent of the primer is water and preferably comprises 5% to 75% of the thermoplastic polyurethane per primer.

In this case, the primer may include 1% to 30% alcohol solvent.

In addition, the sub-material is contained 1% to 10% per primer, and the silicon compound is preferably a silane (SiH ₄ ) material including tetraethylolsosilgate (TEOS).

On the other hand, the present invention; A binder layer coated on the substrate and including a urethane-based address material and a silicon compound-based sub-material; And a transparent conductive layer including carbon nanotubes to be coated on the binder layer.

In this case, it is preferable that the base material includes at least one of a transparent polymer film, sheet, and glass sheet.

In this case, the substrate may include at least one of polyethylene terephthalate (PET), polyether sulfone (PES), polycarbonate (PC).

In this case, it is preferable that the thickness of the film is 10 µm to 1000 µm, and the thickness of the glass sheet is 0.5 mm to 10 mm.

In addition, the binder layer preferably has a thickness of 5 nm to 500 nm.

Primer composition for a carbon nanotube conductive film and a carbon nanotube conductive film having the same according to the present invention has a strong adhesive force to suppress the peeling of the carbon nanotube layer by an external force.

In addition, the primer composition for the carbon nanotube conductive film and the carbon nanotube conductive film having the same according to the present invention have excellent electrical characteristics because the change rate of the sheet resistance is high at high temperature and high temperature and high humidity, thereby greatly improving the reliability as a transparent electrode. Let's do it.

Primer composition for a carbon nanotube conductive film according to the present invention consists of a solution containing a urethane-based addressing material and a silicon compound-based sub-material.

Hereinafter, the technical configuration of the present invention according to the accompanying drawings in detail.

1 is a cross-sectional view showing a schematic configuration of a conductive film according to an embodiment of the present invention.

As shown in FIG. 1, the carbon nanotube conductive film 100 includes a substrate 10, a binder layer 20, and a transparent conductive layer 30.

The base material 10 becomes a base material of a conductive film.

The binder layer 20 is applied to the surface of the substrate 10. The binder layer 20 may be formed on the substrate 10 through various coating methods. The binder layer 20 may be formed by coating a primer solution including an address material and a sub-material on the substrate 10.

The addressing material is made of urethane series. The urethane-based addressing material is coated on the substrate 10 with high adhesive force, and at the same time, the transparent conductive layer 30 to be described later is coated with high adhesive force. Therefore, the address material greatly improves the adhesive force between the substrate 10 and the transparent conductive layer 30.

The secondary material is an adhesion stabilizer and is composed of silicon compounds. The secondary material serves to improve physical and electrical properties, such as reducing the sheet resistance change rate of the carbon nanotube conductive film 100. That is, the sub-materials help to cure the address material and make it excellent in heat resistance and moisture resistance. In addition, the sub-material improves the adhesion between the substrate 10 and the transparent conductive layer 30 to suppress the peeling of the transparent conductive layer 30 by external force after curing and to form a hard coating layer.

After all, since the secondary material is made of a silicon compound-based adhesion stabilizer, when the silicon compound is added to the urethane-based primer solution, it helps to cure the transparent conductive layer 30 and has the least effect on temperature and humidity after coating. Because it is the best effect.

The transparent conductive layer 30 is applied to the binder layer 20 and includes a carbon nanotube (CNT) which is a conductive material. The transparent conductive layer 30 has excellent transparency and conductivity, which are characteristics of a conductive film. Therefore, the transparent conductive layer 30 is preferably carbon nanotubes are connected without breaking each other and as thinly coated as possible. The transparent conductive layer 30 may be made of a single wall carbon nanotube, a double wall carbon nanotube, a multiwall carbon nanotube, a bundle carbon nanotube, or a combination thereof, but is not limited thereto.

As described above, the carbon nanotube conductive film 100 according to the present invention contains a urethane-based addressing material and a silicon oxide-based adhesive stabilizer in the binder layer 20, and the base material 10 and the transparent conductive layer. Maximizing the adhesive force between the (30) and at the same time to reduce the sheet resistance change rate makes the electrical characteristics as a transparent electrode very excellent.

On the other hand, the solvent of the primer is water, preferably containing 5% to 75% of the thermoplastic polyurethane per primer.

The thermoplastic polyurethane is preferably contained 5% to 75% in the primer solution, more preferably 10% to 50%. When the thermoplastic polyurethane is 5% or less, the adhesion between the substrate 10 and the transparent conductive layer 30 is inferior. In addition, when the thermoplastic polyurethane is contained in 75% or more, the coating thickness is increased, and after coating the transparent conductive layer 30, the binder layer 20 coated with microfluidic flow of the coating layer by heat forms the transparent conductive layer 30. The surface resistance will increase remarkably.

In this case, the primer solution may further include 1% to 30% alcohol solvent.

Alcohol solvents serve to improve the smoothness in the coating. When the content of the alcohol solvent is 1% or less, it is not expected to improve the smoothness, and when the content of the alcohol solvent is 30% or more, the dispersibility of the thermoplastic polyurethane solution is lowered to aggregate the thermoplastic polyurethane. More preferably, the content of the alcohol solvent is 5% to 20%.

On the other hand, the silicon compound is preferably a silane (SiH ₄ ) material containing tetraethylolsosilgate (TEOS). Silane material is one of the silicon hydride series, so it is easily mixed with alcohol, it is suitable to be applied to a primer solution containing an alcohol solvent.

In addition, the sub-material is preferably added 1% to 10% per primer. When the adhesion stabilizer is contained in an amount of 1% or less, it is not possible to expect an improvement in adhesion and heat resistance and moisture resistance are not improved. If the adhesive stabilizer is contained in more than 10%, the flexibility of the transparent conductive layer 30 may be impaired.

As such, the primer solution to which the adhesive stabilizer is added is a great factor that can maximize the characteristics of the carbon nanotube conductive film as a transparent electrode according to the change of the composition. That is, the properties that appear after the coating of the transparent conductive layer 30 may vary significantly depending on the composition of the binder layer 20 coated on the substrate 10. Therefore, in order to coat the transparent conductive layer 30 to have an appropriate sheet resistance value and adhesion, the physical properties of the composition of the binder layer 20 to be coated are very important. The present invention proposes a composition of an adhesive stabilizer and a primer solution most suitable for a carbon nanotube conductive film, thereby maximizing the characteristics of the carbon nanotube conductive film as a transparent electrode.

On the other hand, the substrate 10 is preferably at least one of a transparent polymer film (Film), a sheet (Sheet), and a glass sheet.

In addition, the substrate 10 may include at least one of polyethylene terephthalate (PET), polyether sulfone (PES), and polycarbonate (PC). The substrate 10 used for the transparent electrode is preferably a high transmittance film having a total light transmittance of 90% or more and a haze of 1% or less for optical purposes.

In this case, it is preferable that the substrate 10 adopt a film having a thickness of 10 μm to 1000 μm. When the thickness of the film is formed to 10 μm or less, the structural strength decreases, and when the thickness of the film is formed to 1000 μm or more, the transmittance decreases. In addition, it is preferable that the substrate 10 adopts a glass sheet having a thickness of 0.5 mm to 10 mm. If the thickness of the glass sheet is 0.5 mm or less, structural strength cannot be expected. If the thickness of the glass sheet is 10 mm or more, the transmittance is lowered.

On the other hand, the thickness of the binder layer 20 is preferably 5nm to 500nm.

When the coating thickness of the binder layer 20 is formed to 5 nm or less, properties related to the adhesion stability are reduced. In addition, when the coating thickness of the binder layer 20 is formed to be 500 nm or more, the carbon nanotubes are buried in the binder layer 20 when the transparent conductive layer 30 is coated, and the electrical properties thereof are deteriorated. The transmittance of is also lowered.

In addition, the coating method may be used, such as bar coating, roll coating, dip coating, spin coating method, preferably using a gravure coating (Gravure) coating. The gravure coating is generally using a gravure roll (Roll), the gravure roll is placed on the bearing and partially disappeared as it is rotated on the coating pan, the roll scooped by the flexible steel braid floating the coating liquid to return to the contact surface of the substrate Indeed. The gravure coating is advantageous to form a uniform coating film.

In addition, the transparent conductive layer 30 may improve durability and optical characteristics by using various optical coatings. Examples include hard coating and anti-reflection.

In addition, the thermoplastic polyurethane dispersion solution may adopt a transparent liquid, milky or light yellowish color, it is preferable to use a transparent or milky dispersion solution if possible.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited only to the following examples.

Example 1

50 ml of a dispersion of 40% thermoplastic polyurethane and 10 ml of methanol were added to a stirrer and stirred for 10 minutes. 1 mL of tetraethylolsosilgate (TEOS) was added as an adhesive stabilizer to the prepared urethane-based dispersion solution, and stirred well to prepare a primer solution for CNT coating. The primer solution was coated on a transparent PET substrate with a bar coder to form a binder layer. Thereafter, 1 wt% or less of CNT dispersion solution was uniformly coated on the PET substrate coated with a binder layer by spray to form a transparent conductive layer. The sheet resistance, which is an electrical property of the CNT film thus prepared, was measured using a thin film 4-point probe.

Example 2

50 ml of the thermoplastic polyurethane 50% dispersion solution and 20 ml of alcohol mixed with methanol and ethanol 1: 1 were put in a stirrer and stirred for 10 minutes. 1 mL of tetraethylolsosilgate (TEOS) was added as an adhesive stabilizer to the prepared urethane-based dispersion solution, and stirred well to prepare a primer solution for CNT coating. The primer solution was coated on a transparent PET substrate with a bar coder to form a binder layer. Thereafter, 1 wt% or less of CNT dispersion solution was uniformly coated on the PET substrate coated with a binder layer by spray to form a transparent conductive layer. The sheet resistance, which is an electrical property of the CNT film thus prepared, was measured using a thin film 4-point probe.

Comparative Example 1

A transparent conductive layer was formed by uniformly coating a CNT dispersion solution of 1wt% or less with a spray on a transparent PET substrate. The sheet resistance, which is an electrical property of the CNT film thus prepared, was measured using a thin film 4-point probe.

Comparative Example 2

50 mL of a dispersion solution containing 40% of thermoplastic polyurethane and 10 mL of methanol were added to a stirrer and stirred for 10 minutes to prepare a primer solution for CNT coating. The primer solution was coated on a transparent PET substrate with a bar coder to form a binder layer. Thereafter, 1 wt% or less of CNT dispersion solution was uniformly coated on the PET substrate coated with a binder layer by spray to form a transparent conductive layer. The sheet resistance, which is an electrical property of the CNT film thus prepared, was measured using a thin film 4-point probe.

Comparative Example 3

50 ml of a thermoplastic acrylic 40% dispersion solution and 10 ml of methanol were added to a stirrer and stirred for 10 minutes to prepare a primer solution for CNT coating. The primer solution was coated on a transparent PET substrate with a bar coder to form a binder layer. Thereafter, 1 wt% or less of CNT dispersion solution was uniformly coated on the PET substrate coated with a binder layer by spray to form a transparent conductive layer. The sheet resistance, which is an electrical property of the CNT film thus prepared, was measured using a thin film 4-point probe.

Comparative Example 4

50 ml of the thermosetting melamine resin 50% dispersion solution, methanol 10ml and butyl cellosolve 10ml into a stirrer was stirred for 10 minutes to prepare a primer solution for CNT coating. The primer solution was coated on a transparent PET substrate with a bar coder to form a binder layer. Thereafter, 1 wt% or less of CNT dispersion solution was uniformly coated on the PET substrate coated with a binder layer by spray to form a transparent conductive layer. The sheet resistance, which is an electrical property of the CNT film thus prepared, was measured using a thin film 4-point probe.

The CNT film prepared as described above was evaluated for electrical properties as a transparent electrode by high temperature, high humidity, high temperature and high humidity, and thermal shock test based on the transparent electrode reliability evaluation criteria for the touch panel, and the results are shown in Table 1.

Reliability evaluation criteria have a rate of change of sheet resistance within ± 10% and the evaluation method is as follows.

The high temperature test was left for 240 hours in an 80 ° C chamber.

The low temperature test was left for 240 hours in a -40 ° C chamber.

The high temperature and high humidity test was left for 240 hours in a 65 degreeC, 95% relative humidity chamber.

Thermal shock test was measured 10 times, 30 minutes at -40 ℃, 30 minutes at 80 ℃.

 division  Coating substrate  Primer Type  additive  Initial sheet resistance (Ω / □)  Reliability item (R1 / R2) High temperature (80 ℃, 240 hours) Low temperature (-40 ℃, 240 hours) High Temperature & Humidity (65 ℃, 95%, 240hours) Thermal Shock (-40 ~ 80 ℃ for 30 minutes, 10 times) Example 1 PET Urethane 40% Methanol TEOS 500 0.90 0.90 0.94 0.96 Example 2 PET Urethane 50% Alcohol TEOS 500 0.90 0.88 1.04 0.90 Comparative Example 1 PET none none 500 0.88 0.88 1.92 1.02 Comparative Example 2 PET Urethane 40% Methanol none 500 0.88 0.86 1.80 1.10 Comparative Example 3 PET Acrylic 40% Methanol none 500 0.85 0.85 2.40 1.20 Comparative Example 4 PET Melamine 50% Methanol Butyl Cellosolve none 500 0.84 0.84 1.90 1.21

(Where R1 is initial sheet resistance and R2 is final sheet resistance)

According to Examples 1 and 2, tetraethylolsosilgate, an adhesion stabilizer, was added as an additive to the urethane-based primer solution. As a result, the adhesion between the substrate and the transparent conductive layer was significantly increased. This was shown to prevent the influence of temperature or humidity in the reliability evaluation. The urethane-based primer was well coated on the PET substrate, it was confirmed that the binder effective for CNT properties.

However, according to Comparative Example 1, both the primer and the adhesive stabilizer were not used for the general PET substrate, and as a result, the adhesive strength between the substrate and the transparent conductive layer was lowered, and the change in the sheet resistance in the environment of high temperature and high humidity was greatly affected by the temperature and humidity. Increased by more than 10%.

In addition, according to Comparative Example 2, only the urethane-based primer solution was coated on the PET substrate, and the adhesive stabilizer was not used. As a result, the adhesion between the substrate and the transparent conductive layer was excellent, but the sheet resistance change rate was 1.80 in the high temperature and high humidity test.

In addition, according to Comparative Examples 3 and 4, only the primer solution of the acrylic-based, melamine-based was coated on the PET substrate, and no adhesive stabilizer was used. As a result, the adhesion between the substrate and the transparent conductive layer was excellent, but the sheet resistance change rate was 2.4 and 1.9 in the high temperature and high humidity test, respectively.

As such, when the coating was performed using both a urethane-based primer and an adhesive stabilizer, all sheet resistance change rates were less than 10% in the reliability test. However, when only urethane series is used alone or not, or when only another primer solution is coated, the sheet resistance change rate is 10% or higher in the high temperature, low temperature, and high temperature and high humidity tests, and thus the reliability as a CNT transparent electrode is significantly reduced. It became.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and any person skilled in the art to which the present invention pertains may have various modifications and equivalent other embodiments. Will understand. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a cross-sectional view showing a schematic configuration of a conductive film according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: base material 20: binder layer

30: transparent conductive layer 100: carbon nanotube conductive film

Claims (9)

Primer composition for a carbon nanotube conductive film consisting of a solution containing a urethane-based addressing material and a silicon compound-based sub-material. The method of claim 1, The solvent of the primer is water, primer composition for a carbon nanotube conductive film, characterized in that it comprises 5% to 75% of the thermoplastic polyurethane per primer. The method of claim 2, The primer is a primer composition for a carbon nanotube conductive film, characterized in that it comprises an alcohol solvent of 1% to 30%. The method of claim 1, The sub-material is contained 1% to 10% per primer, the silicon compound is a primer composition for carbon nanotube conductive film, characterized in that the silane (SiH ₄ ) material containing tetraethylolsosilicide (TEOS). materials; A binder layer coated on the substrate and including a urethane-based address material and a silicon compound-based sub-material; And Carbon nanotube conductive film comprising a; a transparent conductive layer including carbon nanotubes to be applied to the binder layer. The method of claim 5, The substrate is a carbon nanotube conductive film, characterized in that it comprises at least one of a transparent polymer film, sheet, glass sheet. The method of claim 6, The substrate is a carbon nanotube conductive film comprising at least one of polyethylene terephthalate (PET), polyether sulfone (PES), polycarbonate (PC). The method of claim 6, The thickness of the film is 10㎛ to 1000㎛, carbon nanotube conductive film, characterized in that the thickness of the glass sheet is 0.5mm to 10mm. The method of claim 5, The binder layer is carbon nanotube conductive film, characterized in that the thickness of 5nm to 500nm.

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