KR20160076047A - electrically conductive coating composition and manufacture method thereof - Google Patents

Abstract

The present invention relates to an electrically conductive coating composition and a preparation method thereof, wherein the electrically conductive coating composition is prepared from dispersing expanded graphite having excellent electrical conductivity in resin to produce a binder resin, and combining silver powder and carbon powder with the binder resin. The present invention provides a composition for a coating agent having excellent electrical conductivity that is prepared from dispersing expanded graphite in a synthetic resin or solvent, and mixing this expanded graphite dispersion with silver powder and carbon powder.

Description

[0001] The present invention relates to a coating composition having excellent electrical conductivity and an electrically conductive coating composition and manufacture method thereof.

The present invention relates to a coating composition having excellent electrical conductivity and a method for producing the coating composition. More specifically, it relates to an electrically conductive resin composition which is capable of dispersing an expanded graphite having excellent electrical conductivity in a resin to form a binder resin, and mixing the binder resin with a silver powder and a carbon powder to produce a coating composition having a better electrical conductivity Excellent coating composition and a process for producing the same.

Conductive polymer complexes are composed of organic compounds and conductive materials It is possible to provide a variety of processability, light weight, and mass production capability, as well as functions such as electrostatic elimination by electroconductive properties, shielding and absorption of harmful electromagnetic waves and electrochromism, And is widely applied to various industrial fields such as alignment films, sensors, photovoltaic cells, catalyst aids, electronic parts, electromagnetic wave shielding agents, functional clothes, and functional shoes.

Conductive materials for synthesizing conductive polymer complexes include various materials such as nano-carbon materials, carbon nanotubes (CNT), graphene, and graphite. Research on techniques for synthesizing conductive polymer complexes It is actively proceeding.

Currently, carbon nanotubes are applied as field emission devices to parts such as semiconductor parts and displays (LEDs). In the field of electrical and electronic engineering, precision machinery industry, fine chemical industry, etc., Carbon nanotube technology has been actively used for the purpose of lowering production efficiency and preventing defective rate.

Carbon nanotubes (CNTs) consist of single-walled carbon nanotubes (SWNTs) with hollow cylinders in the form of cylindrically sealed two-dimensional grapheme sheets, And multi-walled carbon nanotubes (MWNTs) overlapping one another. Due to its quasi-one-dimensional quantum structure, these quantum phenomena have been observed. The carbon nanotubes have a field emission effect with a stronger electric field than other materials due to their long lengths of about 1000 times the diameters, And has a high electric conductivity similar to that of the above.

And graphite is a crystal belonging to the hexagonal system with a crystal structure such as crystal, and it is also called "kaolin". It has a black color and metallic luster. It is also used as an electric conductor, a pencil lead, a crucible, an electric arc furnace, an arc electrode and the like, and is also used as a sliding material. Graphite is more resistant to heat than other materials, has a very low coefficient of thermal expansion, and is characterized by its excellent thermal conductivity and electrical conductivity. Its shape, color, gloss, hardness, specific gravity, heat and electricity Conductivity and various physical properties.

Natural graphite has carbon as its component, and most of the crystals are hexagonal and partly triplet. Carbon is connected in a hexagon like a benzene ring, and these hexagons form a continuous layer forming a plate. The carbon atoms have three strong covalent bonds in the plane and the remaining one is bound to the upper and lower layers. The height of one layer on the hexagonal plate is 3.40 ANGSTROM, and the distance between the closest carbons in the hexagonal ring is 1.42 ANGSTROM. The distance between the upper and lower layers of the plate is much larger than the center distance of two carbon atoms. For this reason, graphite has good electrical conductivity because the electrons above the hexagonal plate can move somewhat freely. Diamond, which is homogenous with graphite, is a perfect insulator because all four electrons have strong covalent bonds.

Expanded graphite means that crystalline graphite is oxidized into chromic acid and dilute sulfuric acid solution and, when heated rapidly, water contacts between the layers of graphite and is expanded to 100 to 700% of the initial volume. Such expanded graphite is used in insulating materials for steel casting, as a cover for covering ingot, for high-elasticity refractory of furniture and mattresses. In recent years, it has been actively used as a heat dissipation material, a heat conduction sheet, a flame retardant, a conductive filler, a semiconductor part, a display (LED) In the case of carbon nanotubes (CNTs) similar to those of graphite, the yield is very low when they are subjected to purification after synthesis. Therefore, even if synthesized using cheap materials, the final product is expensive, while graphite is very cheap In the case of single-wall carbon nanotubes (SWNTs), metal and semiconductor characteristics are different not only depending on the chirality and diameter of SWNTs but also because they have different band gaps even though they have the same semiconductor characteristics. In order to take advantage of the properties or metallic properties, it is necessary to separate all the SWNTs, which is known to be very difficult.

Patent Literatures on Electroconductive Polymeric Composites The conductive polyurethane resin in which graphene is mixed after thermoplastic elastomers are synthesized in Examples 1 to 5 of Korean Patent Registration No. 919611 and thermoplastic There is known a conductive polyurethane resin which mixes expanded graphite after synthesizing an elastomer. However, in the case of the above-mentioned patents, a conductive resin such as graphene or expanded graphite is simply mixed with a polymer resin already synthesized to impart conductivity to the polymer resin The graphene or expanded graphite is not uniformly dispersed uniformly in the polymer resin due to the cohesive property of the fine powder, and thus there is a possibility that the electroconductive property can not be exhibited properly.

Also disclosed in Korean Patent Publication No. 2010-136079 is a conductive foamed resin composition comprising 0.1 to 5 parts by weight of carbon nanotubes surface-modified with a thermoplastic resin. However, even in the above-mentioned patent, There is a possibility that the above-mentioned problems may occur as a conductive foamed resin mixture in which nanotubes are mixed and foamed.

Korean Patent Registration No. 10-0965106

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems described above, and it is an object of the present invention to provide a coating composition which is excellent in electrical conductivity by dispersing expanded graphite having excellent electrical conductivity into a binder resin and mixing the binder resin with silver powder and carbon powder And to provide a method for producing the same.

According to the present invention, it is possible to provide a coating material having excellent electrical conductivity, which is prepared by dispersing expanded graphite in a synthetic resin and a solvent, mixing silver powder and carbon powder in the dispersed expanded graphite dispersion, Lt; / RTI >

Meanwhile, the synthetic resin is cellulose acetate butyrate (cellulose acetate butyrate).

On the other hand, the solvent is dimethylformamide (dimethylformamide, DMF).

On the other hand, the expanded graphite is 10 to 40 parts by weight, the silver powder is 50 to 70 parts by weight, and the carbon powder is 10 to 30 parts by weight based on 100 parts by weight of the total amount of the synthetic resin and the solvent.

According to another aspect of the present invention, there is provided a method for producing a graphite sheet, comprising: a first dispersion step of uniformly dispersing expanded graphite in a synthetic resin and a solvent by ultrasonic waves; And a second dispersion step of mixing a silver powder and a carbon powder into an expanded graphite dispersion dispersed by the first dispersion step and then dispersing the mixture through a roll mill, A method for preparing a composition is provided.

Meanwhile, the synthetic resin is cellulose acetate butyrate, and the solvent is dimethylformamide (dimethylformamide, DMF).

Meanwhile, in the first dispersion step and the second dispersion step, expanded graphite is contained in an amount of 10 to 40 parts by weight, the silver powder is contained in an amount of 50 to 70 parts by weight, and the carbon powder is dispersed in 10 to 40 parts by weight based on 100 parts by weight of the total amount of the synthetic resin and the solvent. 30 parts by weight.

The present invention has the effect of producing a coating composition having better electrical conductivity by dispersing expanded graphite having excellent electrical conductivity in a resin to form a binder resin, and mixing silver powder and carbon powder with the binder resin.

FIG. 1 is a photograph showing the surface morphology (SEM) after mixing only expandable graphite with resins and solvents (Comparative Examples 1 to 3) in a method of manufacturing a coating composition excellent in electrical conductivity according to an embodiment of the present invention.
FIG. 2 is a graph showing the surface morphology (SEM) of carbon powders mixed with resin and solvent (Examples 1 to 3) in addition to expanded graphite in the method of producing a coating composition having excellent electrical conductivity according to an embodiment of the present invention This is the picture shown.
FIG. 3 is a graph showing the surface morphology (SEM) of the resin and the solvent after mixing the silver powder together with the expanded graphite in the method of manufacturing the coating composition excellent in electrical conductivity according to the embodiment of the present invention (Examples 4 to 6) This is the picture shown.
FIG. 4 is a test report showing the surface resistance value of a resin and a solvent mixed with silver powder in addition to expanded graphite (Example 5) in a method of manufacturing a coating composition excellent in electrical conductivity according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The coating composition having excellent electrical conductivity according to the present invention can be prepared by dispersing expanded graphite in a synthetic resin and a solvent and then mixing silver powder and carbon powder into the dispersed expanded graphite dispersion do. Since the expanded graphite is expanded graphite and is manufactured in the same manner as expanded graphite generally produced, a description thereof will be omitted.

In particular, the synthetic resin is preferably cellulose acetate butyrate (cellulose acetate butyrate). A variety of resins can be used for the synthetic resin, but cellulose acetate butyrate (cellulose acetate butyrate) is more advantageous in terms of dispersion and viscosity.

Particularly, the solvent is preferably dimethylformamide (dimethylformamide, DMF). Although various solvents can be used, dimethylformamide (dimethylformamide, DMF) is more advantageous in terms of dispersion and viscosity.

The expanded graphite preferably contains 10 to 40 parts by weight of the graphite powder, 50 to 70 parts by weight of the silver powder, and 10 to 30 parts by weight of the carbon powder, based on 100 parts by weight of the synthetic resin and the solvent. In particular, when the expanded graphite is used in an amount less than the above-mentioned amount, there is a possibility that the electrical conductivity is deteriorated. When the expanded graphite is used in an amount exceeding the above amount, there is a fear that the viscosity becomes high and dispersion is not good. In addition, in the case of silver powder and carbon powder, it is more preferable to use them within the respective weight parts for the same reason as expanded graphite.

Hereinafter, a method for preparing a coating composition having excellent electrical conductivity according to the present invention will be described.

The first dispersion step is a step of uniformly dispersing expanded graphite in a synthetic resin and a solvent by ultrasonic waves. Meanwhile, the synthetic resin is cellulose acetate butyrate, and the solvent is preferably dimethylformamide (dimethylformamide, DMF). Particularly, in the first dispersion step, when the ultrasonic generator is used, the dispersion time is saved and the maximum particle size of the dispersion can be minimized as compared with the case of using a general stirrer or a high-speed dispersion machine, and it is more preferable to disperse the dispersion using the ultrasonic generator .

The second dispersion step is a step of mixing Silver powder and Carbon powder into the expanded graphite dispersion dispersed by the first dispersion step and then dispersing it through a roll mill. In particular, when the second dispersion step is carried out using a roll mill (especially a three-roll mill), the maximum particle size of the dispersion can be minimized and the degree of dispersion can be evenly distributed.

Meanwhile, in the first dispersion step and the second dispersion step, expanded graphite is contained in an amount of 10 to 40 parts by weight, the silver powder is contained in an amount of 50 to 70 parts by weight, and the carbon powder is dispersed in 10 to 40 parts by weight based on 100 parts by weight of the total amount of the synthetic resin and the solvent. 30 parts by weight. The reason is the same as the above.

[Table 1] shows the case where only the expanded graphite is mixed with the resin and the solvent (Comparative Examples 1 to 3), the case where carbon powder is mixed with the resin and the solvent other than the expanded graphite (Examples 1 to 3) And examples in which silver powder other than expanded graphite was mixed in the solvent (Examples 4 to 6). The resin used was cellulose acetate butyrate (CAB-551-0.01) manufactured by EASTMAN. Dimethylformamide (DMF) having excellent affinity was used as a solvent. The size of expanded graphite dispersed by ultrasonic waves was 5 to 10 μm and the thickness was 80 nm , Carbon powder EC600JD manufactured by MITSUBISH CHEMICAL Co., Ltd., and silver powder 0.5 to 7.5 mu m in diameter were used. The weight ratios are shown in Table 1 below.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Expanded graphite-1 Expanded Graphite-2 Expanded graphite-3 Expanded Graphite / Conductive Carbon-1 Expanded Graphite / Conductive Carbon-2 Expanded Graphite / Conductive Carbon-3 Expansion Graphite / Silver-1 Expansion Graphite / Silver-2 Expanded Graphite / Silver-3 Suzy CAB (Cellulose acetate butyrate) 60 50 40 50 50 50 50 50 50 menstruum DMF 50 50 50 50 50 50 50 50 50 Conductive powder Expanded graphite 40 50 60 20 30 40 10 20 30 Conductive carbon 20 20 20 silver 60 60 60

/sq)Surface resistance

/ sq) 70 50 40 40 20 10 5 0.5 0.01

Therefore, the surface resistance values of the coating compositions prepared according to Comparative Examples 1 to 6 are well shown in Table 1 above. In particular, when carbon powder and silver powder are mixed as in Examples 1 to 6 It was found that the surface resistance value was lower than that of Comparative Example 1 and thus the electric conductivity was excellent. FIGS. 1 to 3 show photographs of the surface shape (SEM) for each of the comparative examples and the embodiments. Particularly, FIG. 4 shows the test results of Example 5, Ω / sq), indicating that the electrical conductivity is excellent.

Accordingly, when the coating composition according to the present invention is used, it has excellent electrical conductivity and can be used in a wide variety of fields such as electrode materials, liquid crystal alignment layers of liquid crystal display devices, sensors, photovoltaics, catalyst aids, electronic components, electromagnetic shielding agents, functional clothes, There is an advantage that it can be widely used as a coating agent.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Therefore, the embodiments disclosed in the present specification are intended to illustrate rather than limit the present invention, and the scope and spirit of the present invention are not limited by these embodiments. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of the present invention should be construed as being included in the scope of the present invention.

Claims (7)

A coating composition having excellent electrical conductivity, prepared by dispersing expanded graphite in a synthetic resin and a solvent, and then mixing silver powder and carbon powder into the dispersed expanded graphite dispersion.
The method according to claim 1,
Wherein the synthetic resin is cellulose acetate butyrate (cellulose acetate butyrate).
3. The method of claim 2,
Wherein the solvent is dimethylformamide (dimethylformamide, DMF).
The method of claim 3,
Characterized in that it comprises 10 to 40 parts by weight of expanded graphite, 50 to 70 parts by weight of silver powder, and 10 to 30 parts by weight of carbon powder, based on 100 parts by weight of the total amount of the synthetic resin and the solvent. Composition.
A first dispersion step of uniformly dispersing expanded graphite in a synthetic resin and a solvent by ultrasonic waves; And
And a second dispersion step of mixing silver powder and carbon powder into the expanded graphite dispersion dispersed by the first dispersion step and then dispersing the mixture through a roll mill. ≪ / RTI >
6. The method of claim 5,
Wherein the synthetic resin is cellulose acetate butyrate (cellulose acetate butyrate), and the solvent is dimethylformamide (dimethylformamide, DMF).
The method according to claim 6,
The first dispersing step and the second dispersing step may include 10 to 40 parts by weight of expanded graphite, 50 to 70 parts by weight of silver powder and 10 to 30 parts by weight of carbon powder based on 100 parts by weight of the total amount of the synthetic resin and the solvent Wherein the coating composition has an excellent electrical conductivity.

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