KR101147227B1 - manufacturing mathod of conductive coatings with metal oxide-wrapped carbon nanotubes and the conductive coatings thereby - Google Patents

Abstract

The present invention is for coating a metal oxide on the surface of the carbon nanotubes, by uniformly coating the metal oxide on the surface of the carbon nanotubes by adding a metal oxide precursor and a stabilizer to the carbon nanotube (CNT) dispersion and agitated on the substrate The manufacturing method of the conductive coating film using the carbon nanotubes coated with the metal oxide formed thereon and the conductive coating film is a technical gist. Accordingly, by coating a carbon nanotube coating liquid coated with a metal oxide on a substrate to prepare a conductive coating film, not only improves high temperature heat and moisture resistance, but also minimizes bonding resistance in a carbon nanotube network using a semiconducting metal compound. There is an advantage of improving the conductivity by minimizing the increase in resistance as the binder is added.

Carbon Nanotube Metal Oxide Coating Film Functionalized Titanium Oxide

Description

Manufacturing method of conductive coating film using carbon nanotubes coated with metal oxide and its conductive coating film {manufacturing mathod of conductive coatings with metal oxide-wrapped carbon nanotubes and the conductive coatings}

The present invention is to coat the metal oxide on the surface of the carbon nanotubes, in particular, the surface of the carbon nanotubes (CNT) dispersed in the solvent is coated with the metal oxide in a simple solution process and coated on the substrate to improve the high temperature heat and moisture resistance A method of manufacturing a conductive coating film using carbon nanotubes coated with a metal oxide capable of minimizing the resistance increase as a binder is added by minimizing the bonding resistance in a carbon nanotube network using a semiconducting metal compound and a conductive coating film thereof It is about.

Since the transparent conductive film has high conductivity (for example, sheet resistance of ¹ × 10 ³ Ω / sq or less) and high transmittance in the visible region, the transparent conductive film may be used for solar cells, liquid crystal display devices, plasma display panels, other light receiving elements In addition to being used as an electrode, it is used as a transparent electromagnetic shielding material such as an antistatic film and an electromagnetic shielding film used in a window glass of an automobile or a building, and a transparent heating element such as a heat ray reflecting film and a freezing showcase.

Existing doped metal oxide film has a problem of using an expensive process that is inflexible and uses a vacuum deposition method. Recently, techniques for coating carbon nanotubes on top of various substrates have been widely studied in order to solve these problems. The carbon nanotubes have electrical conductivity comparable to that of metals with an electrical resistance of 10 ^-4 Ωcm, and the surface area is more than 1000 times higher than that of the bulk material and is thousands of times longer than the outer diameter, which makes them an ideal material for implementing conductivity. And, there is an advantage that can improve the binding force to the substrate through the surface functionalization. In particular, it is expected that the use of the flexible substrate can be infinite. In this case, in order to improve adhesion to the substrate and secure environmental reliability, a one-component coating solution in which a binder and carbon nanotubes are mixed is used. However, in the case of using a non-conductive binder, the resistance of the coating film can be increased by increasing the bonding resistance of the carbon nanotube network. In addition, if the proper binder is not used, the sheet resistance may increase in an environment of high temperature and high temperature and high humidity.

Therefore, when manufacturing a conductive coating film using such carbon nanotubes, studies to minimize the dispersibility problem and the increase in resistance by a binder that can not be used inevitably is active.

As a conventional technique for minimizing dispersibility problems and resistance increase by using such carbon nanotubes, a polymer material is grown on a surface of a carbon nanotube for dispersibility of carbon nanotubes, or metal particles are used to improve conductivity. Researches such as growing on the tube surface have been conducted.

However, if the nonconducting polymer is grown on the surface of the carbon nanotubes (Korea Patent Office Publication No. 10-2004-0022939), the dispersibility in the solution of the carbon nanotubes can be increased, but the conductivity is significantly reduced, and the conductive polymer is used. In the case of (Korean Patent Application Publication No. 10-2009-0019303), the resistance may increase due to moisture. In addition, when the metal particles are grown on the surface of the carbon nanotubes (Korean Patent Publication No. 10-2003-0036265), there is a disadvantage that the permeability of the coating film using the same rapidly decreases.

Meanwhile, metals such as TiO ₂ , SnO ₂ , ZnO, MgO, V ₂ O ₅ , ZrO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O ₃ , BaTiO ₃ , V ₂ O ₅ , WO ₃ , NiO, etc. Oxide can be manufactured in solution by sol-gel method and exhibits semi-conductivity with band gap through heat treatment after application, minimizing the increase of resistance caused by binder in carbon nanotube network, and its structure is compact. The conductive coating film can be protected from external moisture. Therefore, the use of these metal oxides together in the carbon nanotube network can minimize the increase in resistance and protect the conductive coating layer.

As a conventional technique using such a metal oxide, there is a technique of forming a chemical functional group on the surface of the carbon nanotube and forming a metal oxide film on the carbon nanotube on which the chemical functional group is formed (Korean Patent Office Publication No. 10-2009-0079427). However, this requires a separate chemical functional group formed on the carbon nanotubes and repeated atomic layer deposition to obtain a predetermined thickness is complicated in the manufacturing method, and forming a metal oxide film on the carbon nanotubes on which the chemical functional groups are formed. In this case, there is a problem that the conductivity is lowered, there is a problem that the sheet resistance is lowered in the environment of high temperature, high humidity and durability is lowered.

Accordingly, the present invention has been made to solve the above problems of the prior art, by coating a carbon nanotube (CNT) surface with a metal oxide on a dispersion solution by a simple process and excellent conductivity prepared by coating it on a substrate and It is an object of the present invention to provide a method for producing a conductive coating film using carbon nanotubes coated with metal oxides having improved high temperature heat and moisture resistance and a conductive coating film.

The present invention for achieving the above object, by adding a metal oxide precursor and a stabilizer to the carbon nanotube (CNT) dispersion by stirring and uniformly coating the metal oxide on the surface of the carbon nanotubes and a metal oxide formed by coating it on a substrate Method for producing a conductive coating film using the coated carbon nanotubes and the conductive coating film is a technical gist.

The carbon nanotube dispersion may be prepared by dispersing carbon nanotubes (CNT) in a dispersion solvent using ultrasonic waves, and adding a metal oxide precursor and a stabilizer to the carbon nanotube (CNT) to stir to prepare a coating solution.

In addition, the metal oxide precursor material may be any kind as long as it is dissolved in the solvent used, and may be used without limiting to a specific precursor such as chloride-based, acetate-based or halide. In particular, in order to impart superhydrophilicity to the coating film, it may be performed using titanium tetraethoxide, titanium tetrabutoxide, titanium tetra isopropoxide, zinc acetate, or the like.

In addition, the stabilizer may be used by selecting one or more of triethanolamine, diethanolamine, acetylacetone, diethylene glycol, acetic acid, trifluoroacetic acid, and the stabilizers used are chemically bonded to the metal oxide precursor and carbon It is desirable to have the precursor uniformly coated on the surface of the carbon nanotubes by hydrophobic interaction with the nanotubes. Herein, the stabilizer added during the preparation of the carbon nanotube coating solution is preferably added in an amount of 0.5 to 50 parts by weight based on 100 parts by weight of the carbon nanotubes.

The substrate is one selected from the group consisting of glass, quartz, glass wafers, silicon wafers, and plastics, and the coating layer is sprayed, dip coated, spin coated, screen coated, ink jet printed, pad printed, knife coated, It is made by the method of any one of the key coating and the gravure coating, the solidification is solidified using a heat curing method, and includes a step of heating to remove residual organic matter as necessary. In addition, the carbon nanotubes are preferably made of one selected from single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, and mixtures thereof.

In addition, the carbon nanotube dispersion solvent used in the solvent dispersion step is acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethylene glycol, polyethylene glycol, tetrahydrofuran, dimethylform Amide, dimethylacetamide, N-methyl-2-pyrrolidone, hexane, cyclohexanone, toluene, chloroform, distilled water, dichloro benzene, dimethylbenzene, trimethylbenzene, pyridine, methylnaphthalene, nitromethane, acrylonitrile, octa At least one selected from the group consisting of decylamine, aniline, and dimethyl sulfoxide, wherein the coating liquid is added with a diluting solvent for controlling the concentration of the coating liquid, and the diluting solvent is acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, Isopropyl alcohol, butyl alcohol, ethylene glycol, polyethylene glycol, tetrahydrofuran, dimethylformamide, dimethyl acet Amide, N-methyl-2-pyrrolidone, hexane, cyclohexanone, toluene, chloroform, distilled water, dichlorobenzene, dimethylbenzene, trimethylbenzene, pyridine, methylnaphthalene, nitromethane, acrylonitrile, octadecylamine, aniline , Dimethyl sulfoxide, methylene chloride, and mixtures thereof. The dispersion solvent and dilution solvent are preferably used as a dissolving solvent.

On the other hand, the metal oxide is one selected from TiO ₂ , SnO ₂ , ZnO, MgO, ZrO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O ₃ , BaTiO ₃ , V ₂ O ₅ , WO ₃ , NiO It is preferable to select and use the above, and to add 30-99 weight part with respect to 100 weight part of carbon nanotubes and a metal oxide.

The present invention as described above, the surface of the carbon nanotubes (CNT) dispersed in the solvent is coated with a metal oxide in a simple solution process and coated on the substrate, thereby improving the high temperature heat and moisture resistance as well as the semiconducting metal compound Minimize the bonding resistance in the carbon nanotube network by using, and the effect of improving the conductivity by minimizing the increase in resistance as the binder is added.

In addition, the titanium oxide of the metal oxide can induce super-hydrophilicity by ultraviolet light can be given anti-fog and self-cleaning properties, it has an excellent effect of utilization.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

In the method of manufacturing a conductive coating film using a carbon nanotube coated with a metal oxide according to the present invention, the carbon nanotube dispersion is prepared by mixing a carbon nanotube and a dispersion solvent, and adding a metal oxide precursor and a stabilizer to the dispersed carbon nanotube dispersion to stabilize the mixture. A carbon nanotube coating liquid coated with a metal oxide uniformly on the surface of the carbon nanotubes by hydrophobic interaction between the prepared metal oxide precursor and the carbon nanotubes, coated on the upper surface of the substrate, and solidified to prepare a conductive coating film do.

In addition, the metal oxide precursor material may be any kind as long as it is dissolved in the solvent used, and may be used without limiting to a specific precursor such as chloride-based, acetate-based or halide. In particular, in order to impart superhydrophilicity to the conductive coating film, it may be performed using titanium tetraethoxide, titanium tetrabutoxide, titanium tetraisopropoxide, etc., and zinc acetate hydrate may be used as a precursor of zinc oxide. Can be done.

In addition, the stabilizer may be used by selecting one or more selected from the group consisting of triethanolamine, diethanolamine, acetylacetone, diethylene glycol, acetic acid, trifluoroacetic acid, the stabilizer used is a chemical bond with the metal oxide precursor In addition, the precursor is uniformly coated on the surface of the carbon nanotubes by hydrophobic interaction with the carbon nanotubes. Herein, the stabilizer added during the preparation of the carbon nanotube coating solution is preferably added in an amount of 0.5 to 50 parts by weight based on 100 parts by weight of the carbon nanotubes.

The substrate is one selected from the group consisting of glass, quartz, glass wafers, silicon wafers, and plastics, and the coating layer is sprayed, dip coated, spin coated, screen coated, ink jet printed, pad printed, knife coated, It is made by any one of the key coating and gravure coating, and the solidification is solidified using a thermal curing method, the carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes and their It consists of one selected from the mixture.

In addition, the dispersion solvent in preparing the carbon nanotube dispersion is acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethylene glycol, polyethylene glycol, tetrahydrofuran, dimethylformamide, dimethyl Acetamide, N-methyl-2-pyrrolidone, hexane, cyclohexanone, toluene, chloroform, distilled water, dichlorobenzene, dimethylbenzene, trimethylbenzene, pyridine, methylnaphthalene, nitromethane, acrylonitrile, octadecylamine, At least one selected from the group consisting of aniline and dimethyl sulfoxide, wherein the coating liquid is added with a diluting solvent for controlling the concentration of the coating liquid, and the diluting solvent is acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, isopropyl alcohol. , Butyl alcohol, ethylene glycol, polyethylene glycol, tetrahydrofuran, dimethylformamide, dimethylacetamide, N Methyl-2-pyrrolidone, hexane, cyclohexanone, toluene, chloroform, distilled water, dichlorobenzene, dimethylbenzene, trimethylbenzene, pyridine, methylnaphthalene, nitromethane, acrylonitrile, octadecylamine, aniline, dimethyl sulfoxide It is 1 type selected from the side, methylene chloride, and mixtures thereof, The said dispersion solvent and dilution solvent are used as a dissolving solvent.

On the other hand, the metal oxide is one selected from TiO ₂ , SnO ₂ , ZnO, MgO, V ₂ O ₅ , ZrO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O ₃ , BaTiO ₃ , WO ₃ , NiO It is selected to use the above, and added to 30 to 99 parts by weight based on 100 parts by weight of carbon nanotubes and metal oxides.

Hereinafter, embodiments of the present invention will be described in detail.

≪ Example 1 >

As Example 1 of the present invention, the present invention relates to a technique of forming a conductive coating film having improved conductivity, high temperature heat resistance, and moisture resistance by coating a metal oxide coated carbon nanotube solution on a substrate.

50 mg of the acid-treated carbon nanotubes and 100 ml of ethanol (Ethanol) solvent were mixed in an Erlenmeyer flask and dispersed for 2 hours by an ultrasonic wave to prepare a carbon nanotube dispersion.

50 mg of titanium isopropoxide and 30 mg of acetylacetone as a stabilizer were added to the solution, followed by stirring for 1 hour to prepare a carbon nanotube coating liquid formed by coating a metal oxide, in which titanium oxide was coated on the surface.

The carbon nanotube coating liquid coated with titanium oxide was applied to the glass or the polymer substrate using a spray coater.

1 is a conceptual view of a mechanism in which titanium oxide is uniformly coated on a surface of a carbon nanotube according to Example 1 of the present invention. In FIG. 1a, a titanium oxide precursor is coated on a surface by hydrophobic interaction between a stabilizer and a surface of a carbon nanotube. Figure 1b shows that the titanium oxide is coated on the carbon nanotube surface by removing the stabilizer as it is heated.

Figure 2a shows a photograph of the surface of the conductive coating film according to Example 1 of the present invention observed with an electron scanning microscope, it can be seen that the carbon nanotubes are coated with a metal oxide in the inserted picture.

Figure 3 shows the sheet resistance measurement according to the titanium oxide content and the heat treatment temperature according to Example 1 of the present invention, when the heat treatment at 300 ℃ can be seen that the resistance is reduced by the removal of the stabilizer, the carbon nanotube at 350 ℃ It shows the increase of resistance by oxidation.

4 is a view showing the sheet resistance change with time of the conductive coating film exposed to high temperature and humidity of 80 ℃, 90% relative humidity according to Example 1 of the present invention. As shown, in Example 1 of the present invention, the titanium oxide is uniformly coated on the surface of the carbon nanotubes, thereby minimizing the reduction of sheet resistance caused by the binder, preventing deterioration of the carbon nanotubes at high temperatures, and water adsorption at high temperature and high humidity. The increase in sheet resistance was found to be minimal.

Such a conductive coating film using titanium oxide coated carbon nanotubes can provide supercatalyst properties and organic material decomposition properties by imparting photocatalytic properties to the conductive coating film, which can be utilized in antifogging and self-cleaning fields.

≪ Example 2 >

As Example 2 of the present invention, a titanium oxide was coated in the same manner as in Example 1 of the conductive coating film using a carbon nanotube, was carried out by replacing the oxide precursor with titanium butoxide.

<Comparative Example>

As a comparative example of the present invention, it was prepared in the same manner as in Example 1 of the conductive coating film production technology using a metal oxide-coated carbon nanotube, it was performed without using acetylacetone used as a metal oxide precursor stabilizer.

Figure 2b shows that the road carbon nanotube surface showing the surface morphology of the coating film coated without using acetylacetone is not uniformly coated with titanium oxide. When acetylacetone is not used in FIG. 3, the sheet resistance is rapidly increased by deterioration of carbon nanotubes at 350 ° C., and in the case of not using a stabilizer, moisture resistance is not significantly improved.

Therefore, the present invention is to prepare a carbon nanotube dispersion without the addition of a separate binder, carbon nanotube dispersion process in a simple solution process to the hydrophobic interaction between the stabilizer of the metal oxide precursor and the surface of the carbon nanotubes The metal oxide may be uniformly coated on the surface of the carbon nanotubes, and then coated on the upper surface of the substrate to prepare a conductive coating film. Such a conductive coating film improves transparency, high temperature heat resistance and moisture resistance, and increases conductivity by minimizing resistance increase by a binder.

1-conceptual diagram of a metal oxide coating mechanism according to the present invention.

Fig. 2 shows an electron micrograph of a conductive coating film prepared using (a) a metal oxide coated carbon nanotube according to the present invention, and (b) a conductive coating film using a carbon nanotube coated unevenly with a metal oxide. .

3 is a view showing a sheet resistance change according to the temperature and the metal oxide content according to the present invention.

4-a view showing a sheet resistance change at high temperature and high humidity in accordance with the present invention.

Claims (15)

A first step of preparing a carbon nanotube dispersion by mixing and dispersing carbon nanotubes and a dispersion solvent; A second step of preparing a carbon nanotube coating liquid coated with a metal oxide on the surface of the carbon nanotubes by adding a metal oxide precursor and a stabilizer to the carbon nanotube dispersion by a hydrophobic mutual attraction between the stabilized metal oxide precursor and the carbon nanotubes Wow; And a third step of forming the conductive coating film by applying the carbon nanotube coating solution on a substrate. 2. A method of manufacturing a conductive coating film using carbon nanotubes coated with metal oxides, the method comprising: According to claim 1, The metal oxide contained in the carbon nanotube coating liquid, Method of producing a conductive coating film using a metal oxide coated carbon nanotubes, characterized in that 30 to 99 parts by weight based on 100 parts by weight of carbon nanotubes and metal oxides. According to claim 1, The metal oxide precursor is dissolved in the solvent used, metal oxide coated carbon nano, characterized in that any one or two or more of the chloride-based, acetate-based and halides are used in combination Method for producing a conductive coating film using a tube. The method of claim 3, wherein the metal oxide precursor is one or more selected from the group consisting of titanium tetraethoxide, titanium tetrabutoxide, and titanium tetraisopropoxide, to impart superhydrophilicity to the conductive coating film. Method for producing a conductive coating film using a metal oxide coated carbon nanotubes. The method of claim 1, wherein the metal oxide, Metal oxide, characterized in that at least one of TiO ₂ , SnO ₂ , ZnO, MgO, V ₂ O ₅ , ZrO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O ₃ , BaTiO ₃ , WO ₃ and NiO Method for producing a conductive coating film using the coated carbon nanotubes. The stabilizer of claim 1, wherein the stabilizer is added when the carbon nanotube coating solution is prepared. Method for producing a conductive coating film using a metal oxide coated carbon nanotubes, characterized in that added to 0.5 to 50 parts by weight based on 100 parts by weight of carbon nanotubes. The method of claim 1, wherein the stabilizer, Triethanolamine, diethanolamine, acetylacetone, diethylene glycol, acetic acid, trifluoroacetic acid is a method for producing a conductive coating film using a metal oxide coated carbon nanotubes, characterized in that made of one or more selected from the group consisting of. The method of claim 1, wherein the dispersion solvent, Acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethylene glycol, polyethylene glycol, tetrahydrofuran, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone , Hexane, cyclohexanone, toluene, chloroform, distilled water, dichlorobenzene, dimethylbenzene, trimethylbenzene, pyridine, methylnaphthalene, nitromethane, acrylonitrile, octadecylamine, aniline, and dimethyl sulfoxide Method of producing a conductive coating film using a metal oxide coated carbon nanotubes characterized in that the above. The method of claim 1, wherein the substrate is one selected from the group consisting of glass, quartz, glass wafers, silicon wafers, and plastics. The metal oxide of claim 1, wherein the conductive coating layer is formed by any one of spraying, dip coating, spin coating, screen coating, inkjet printing, pad printing, knife coating, key coating, and gravure coating. Method for producing a conductive coating film using the coated carbon nanotubes. According to claim 1, wherein the carbon nanotube is a metal oxide coated carbon nanotubes, characterized in that consisting of one selected from single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, and mixtures thereof. Method for producing a conductive coating film used. delete delete delete delete

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