Conductive material and manufacturing method thereof
Disclosed is a method of manufacturing a conductive coating film having superior chemical resistance or solvent resistance and durability by chemically bonding a resin having an amine group (—NH 2 ) with carbon nanotubes having a carboxyl group (—COOH). The conductive material having high bondability with carbon nanotubes and superior electrical properties includes carbon nanotubes uniformly contained therein, and thus has appropriate surface resistivity, and thereby can be used for antistatic, electrostatic dissipation and electromagnetic shielding purposes and in transparent or opaque electrodes depending on the resistivity value.
1. A conductive material comprising a polymer resin having an amine group (—NH 2 ) and carbon nanotubes having a carboxyl group (—COOH) chemically bonded thereto and having a peel index of 30% or less, as represented by Equation 1 below:
Peel
Index
(
%
)
=
R
0
-
R
1
R
0
×
100
Equation
1
wherein R 0 is surface resistivity of a conductive material not treated, and R 1 is surface resistivity of a surface of the conductive material from which a tape is peeled off after having been adhered to the surface of the conductive material for 10 min.
2. The conductive material according to claim 1 , wherein a chemical resistance index is 10% or less, as represented by Equation 2 below:
Chemical
Resistance
Index
(
%
)
=
R
0
-
R
2
R
0
×
100
Equation
2
wherein R 0 is surface resistivity of the conductive material not treated, and R 2 is surface resistivity of the conductive material after treatment including immersion in ethanol for 1 hour, removal from ethanol, washing with ethanol and then drying.
3. The conductive material according to claim 1 , wherein the carbon nanotubes having a carboxyl group (—COOH) are used in an amount of 0.001˜2 wt % based on solid content of the polymer resin.
4. The conductive material according to claim 1 , wherein the surface resistivity is 10 −2 ˜10 11 Ω/□.
5. A method of manufacturing a conductive material, comprising:
applying a first dispersion including a first solvent and carbon nanotubes having a carboxyl group (—COOH) on a substrate layer;
removing the solvent from the applied first dispersion, thus forming a network layer of carbon nanotubes having a carboxyl group (—COOH);
applying a second dispersion including the first solvent and a resin having an amine group (—NH 2 ) on the network layer of carbon nanotubes having a carboxyl group (—COOH), so that the second dispersion infiltrates the network layer of carbon nanotubes having a carboxyl group (—COOH);
peeling off the substrate layer; and
forming an amide bond between the resin having an amine group (—NH 2 ) and the carbon nanotubes having a carboxyl group (—COOH).
6. The method according to claim 5 , wherein the forming the amide bond between the resin having an amine group (—NH 2 ) and the carbon nanotubes having a carboxyl group (—COOH) is performed by immersing a coating film obtained by peeling off the substrate layer in a coupling solution including a second solvent and an amide coupling agent.
7. The method according to claim 5 , wherein the forming the amide bond between the resin having an amine group (—NH 2 ) and the carbon nanotubes having a carboxyl group (—COOH) is performed through heating in a temperature range of 40˜400° C. at a heating rate of 1˜10° C./min for 0.5 hours or longer.
8. The method according to claim 5 , wherein the first solvent is one or a mixture of two or more selected from among alcohols, water, acetones, ethers, and toluenes.
9. The method according to claim 5 , wherein the carbon nanotubes having a carboxyl group (—COOH) are prepared through acid treatment.
10. The method according to claim 6 , wherein the second solvent is one or a mixture of two or more selected from among N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF), cyclohexanone, ethanol, methanol and chlorobenzene.
11. The method according to claim 6 , wherein the amide coupling agent is a mixture of one or more selected from among 1,3-dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide.HCl and di-n-hexylcarbodiimide, and 1-hydroxybenzotriazole (HOBt).