KR20210121726A - Highly dispersed nano-carbon coating composition - Google Patents

Abstract

The present invention relates to a nano-carbon coating composition having excellent dispersibility of a nano-carbon material and a small amount of a dispersant. In addition, the nano-carbon coating composition comprises a phthalocyanine compound comprising: a nano-carbon material; a thermosetting binder; a dispersant; and sulfate, and a solvent. The nano-carbon material can be at least one selected from a group consisting of graphene nanoplatelet (GNP), reduced graphene oxide (rGO), CNT, and carbon black.

Description

Highly dispersed nano-carbon coating composition

The present invention relates to a coating solution in which a nano-carbon material is uniformly dispersed, and more particularly, to a nano-carbon coating composition comprising a nano-carbon material such as graphene, CNT, and carbon black, a dispersant, a thermosetting binder, an additive, and a solvent.

Graphite carbon materials such as CNT and graphene are all ^{composed of two-dimensionally conjugated SP 2} hybrid carbon. This unique chemical bond gives graphitic carbon materials excellent properties such as high charge mobility, high charge storage capacity, and mechanical flexibility, thereby providing the possibility to overcome the fundamental limitations of existing silicon-based nanodevices. do. Due to the ideal two-dimensional crystalline properties, graphite carbon material has high mechanical properties of inorganic materials, strong chemical/heat resistance, low density of organic materials, and mechanical flexibility at the same time. In addition, the electrical conductivity can be variously adjusted according to doping, spiral properties, the number of graphite plates, side dimensions, and the like. Due to these excellent properties, nano-carbon materials such as graphene are expected as major candidates for next-generation electronic devices, displays, sensors, and energy conversion/storage. However, in order for the nano-carbon material to be applied to the above-mentioned application fields, it is essential not only to align molecular units, but also to disperse them in macroscopic units to the extent that they can be seen with the naked eye. Therefore, in the coating composition for coating by applying such a nano-carbon material, it is necessary to maintain a very good dispersion state of the nano-carbon material.

Conventionally, a dispersant or a dispersion-type polymer is used for a nano-carbon coating solution such as graphene in a highly dispersed state, but a very large amount of a dispersant is required to maintain the nano-carbon material having a high specific surface area in a highly dispersed state. . As a result, there is a problem in that electrical properties and chemical resistance of the coating layer are deteriorated after curing of the coating solution.

Korean Patent Laid-Open Publication No. 10-2010-0133075 Japanese Patent Publication No. 5169277

It is an object of the present invention to provide a nano-carbon coating composition having excellent dispersibility of the nano-carbon material and at the same time not having a large amount of dispersant.

In order to achieve the above object, in the present invention, it is possible to provide a nano-carbon coating composition comprising a nano-carbon material, a thermosetting binder, a dispersant, a phthalocyanine compound including sulfate, and a solvent.

The nano-carbon material may be at least one selected from the group consisting of graphene nano platelet (GNP), reduced graphene oxide (rGO), CNT, and carbon black.

In addition, the phthalocyanine compound including sulfate is copper phthalocyanine-tetrasulfonic acid tetrasodium salt, nickel phthalocyanine-tetrasulfonic acid tetrasodium salt, and phthalocyanine tetrasulfonic acid tetrasodium salt. It may be at least one selected from the group consisting of tetrasulfonate hydrate).

In addition, the size of the phthalocyanine compound may be 1 ~ 100nm.

In addition, the nano-carbon coating composition may include 0.001 to 5.0% by weight of the phthalocyanine compound based on the total composition.

In addition, the solvent is MEK (Methyl Ethyl Ketone), n-butyl acetate (n-Butyl Acetate), EA (Ethyl Acetate), IPA (Isopropyl Acetate), MIBK (Metyl Isobutyl Ketone), DMF (Dimethyl Formamide), PGMEA ( Propylene Glycol Methyl Ether Acetate), ethanol, and water may be at least one selected from the group consisting of.

In addition, the nano-carbon coating composition may include 0.01 to 40.0 wt % of the nano-carbon material based on the total composition.

In addition, the nano-carbon coating composition may include 0.001 to 10.0% by weight of the dispersant based on the total composition.

In addition, the dispersant includes a polymer block copolymer having a pigment affinity group, and the pigment affinity group may be any one of cationic, anionic, nonionic, salt-like.

In addition, the present invention may provide a conductive ink comprising the various nano-carbon coating compositions described above.

Since the nano-carbon coating composition provided through the present invention can maintain a highly dispersed state of the nano-carbon material even if the amount of the dispersant is not large, the flowability and TI (Thixotropy Index) properties of the coating composition can be improved and cured after application The electrical properties and chemical resistance of the film can be improved.

1 is a diagram showing a state in which a phthalocyanine compound containing sulfate is adsorbed on the surface of graphene powder.
2 shows the structural formula of copper phthalocyanine tetrasulfonic acid tetrasodium salt.

Hereinafter, the configuration and operation of the embodiment of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, when a part 'includes' a certain component, this means that other components may be further included rather than excluding other components unless otherwise stated.

The present invention provides a nano-carbon coating composition comprising a nano-carbon material, a thermosetting binder, a dispersant, a phthalocyanine compound including sulfate, and a solvent.

The nano-carbon material refers to a carbon material having a thickness or diameter of 100 nm or less. Representative examples of such nano-carbon materials include graphene nano platelet (GNP), reduced graphene oxide (rGO), carbon nanotubes (CNT), and carbon black. The nano-carbon material itself has excellent electrical conductivity and can form a transparent film when it is evenly dispersed and applied in a solution due to its nano-scale size. It can be used in various fields such as a film-forming coating solution. As such a nano-carbon material, GNP, CNT, rGO, carbon black, etc. may be used, which may be selected according to price and desired characteristics. At this time, only one type of these nano-carbon materials may be included in the coating composition, and several types of nano-carbon materials are mixed and used, such as not only one type, but a combination of GNP and CNT depending on the desired properties, so that conductivity or transparency can be controlled. do. Among the nano-carbons used, CNTs can be either SWNT (Single Walled Carbon Nanotubes) or MWNT (Multi Walled Carbon Nanotubes).

On the other hand, it is difficult to maintain a stable dispersion state in solution because the nano-carbon material has a very large specific surface area and no functional groups on the surface, so they strongly attract each other and aggregate. Conventionally, it was necessary to increase the amount of the dispersant to compensate for the large specific surface area and insufficient electrostatic force in order to disperse the nano-carbon material in the coating composition containing the solvent. If the amount of the dispersant is increased in this way, the dispersed state can be maintained, but due to the dispersant remaining after curing of the coating solution, there is a problem in that the electrical conductivity is lowered and the chemical resistance of the cured film is deteriorated. In the present invention, this problem can be solved by reducing the amount of the dispersant by providing a composition containing a small amount of the phthalocyanine compound, and furthermore, the flowability and TI (Thixotropy Index) of the coating solution are improved by improving the dispersibility despite the reduced dispersant. was able to do

The phthalocyanine compound containing sulfate is a nano-grade powder, and as shown in FIG. 1, it is easily attached to the surface of the hydrophobic nano-carbon material by van der Waals force. The smaller the size of the phthalocyanine compound than the nano-carbon material that requires dispersion It is easily adsorbed to the surface of the carbon material. Although some dimensions of nano-carbon materials are only several to tens of nanometers, the overall size can reach several microns. Therefore, considering the size of such a nano-carbon material, the size of the phthalocyanine compound is preferably 1 ~ 100nm. This is because, if it is too large, the van der Waals force becomes difficult to act, and a phthalocyanine compound that is too small is difficult to synthesize.

The phthalocyanine compound containing sulfate can make the nano-carbon material to be easily dispersed in an aqueous solution by modifying the surface of the nano-carbon material, and in particular, including a sulfate, which is a hydrophilic group, can further increase the dispersibility in the aqueous solution.

More specifically, examples of the phthalocyanine compound containing sulfate include copper phthalocyanine-tetrasulfonic acid tetrasodium salt, nickel phthalocyanine-tetrasulfonic acid tetrasodium salt, and phthalocyanine tetrasulfonic acid tetrasodium salt. (Phthalocyanine tetrasulfonate hydrate) any one or a combination thereof may be used. The structural formula of copper phthalocyanine tetrasulfonic acid tetrasodium salt is shown in FIG.

The content of the phthalocyanine compound is preferably 0.001 to 5.0% by weight, more preferably 0.01 to 4.0% by weight, based on the total composition. If the phthalocyanine compound is too much, the conductivity of the nano-carbon material may be reduced, and if it is less than 0.001 wt %, it is difficult to maintain satisfactory dispersion properties through surface modification.

In addition, the solvent used in the composition is MEK (Methyl Ethyl Ketone), n-butyl acetate (n-Butyl Acetate), EA (Ethyl Acetate), IPA (Isopropyl Acetate), MIBK (Metyl Isobutyl Ketone), DMF (Dimethyl Formamide) , PGMEA (Propylene Glycol Methyl Ether Acetate), ethanol, water may be any one or a mixture thereof. In particular, as the phthalocyanine compound containing sulfate is used, the surface of the nano-carbon material, which is originally hydrophobic, becomes hydrophilic, so that water can be used as a solvent, thereby making it possible to make an eco-friendly coating composition.

The content of the solvent in the composition may be the remainder except for the phthalocyanine compound including the nano-carbon material, the thermosetting binder, the dispersant and the sulfate.

In addition, the nano-carbon material in the composition may include 0.01 to 40.0 wt%, more preferably 0.1 to 30.0 wt%, based on the total composition. If the content of the nano-carbon material is too high, the viscosity increases due to the high specific surface area of the nano-carbon material, and mixing becomes difficult, making the dispersion process difficult. In addition, if it is too low, there is no contact between the nano-carbon materials, so that desired conductivity, heat dissipation, and barrier properties (properties that block gas or liquid) cannot be obtained.

The thermosetting binder included in the composition may be used by dissolving an epoxy resin, a polyester resin, a polyurethane resin, etc. in an appropriate solvent. At this time, the preferred content of the thermosetting binder is 0.1 to 40 wt%. If it is too low, physical properties such as hardness are not maintained in the final coating layer, and if it is too high, conductivity and fairness are poor, making it difficult to use.

The dispersant may include 0.001 to 10.0 wt% based on the total composition, and more preferably 0.01 to 8.0 wt%. A minimum amount of dispersant is required to maintain the dispersibility of the composition, because it is difficult to impart electrostatic repulsion and steric stabilization to the nano-carbon material. On the other hand, if too much, the electrical conductivity and chemical resistance of the coating film formed by the composition may be reduced.

In addition, the dispersant may include a polymer block copolymer having a pigment affinity group, wherein the pigment affinity group may be any one of cationic, anionic, nonionic, salt-like. These dispersants can help maintain a stable dispersion state of the nano-carbon material through electrostatic repulsion and steric stabilization.

The specific composition of the above-described composition is 0.01 to 40% by weight of the nano-carbon material, 0.1 to 40% by weight of the thermosetting binder, 0.001 to 10% by weight of the dispersant, 0.001 to 5% by weight of the phthalocyanine compound containing sulfate, and the remainder is the solvent and other unavoidable impurities can be done with

The above-described nano-carbon composition can be used as a conductive ink for forming conductivity on the coating surface. In particular, when graphene is used as a nano-carbon material, it is possible to secure all of the conductivity, heat dissipation, and barrier properties. When CNT or carbon black is used, conductivity can be obtained.

(Example)

[Manufacture of binder]

800 g of MEK (manufactured by Samchun Chemical) was put into the flask, and after raising to 80 °C, 200 g of polyester resin (manufactured by SK Chemical) was divided into three portions and stirred for 2 hours.

[Production of composition]

After adding the prepared binder and copper phthalocyanine tetrasulfonic acid tetrasodium salt (Sigma-Aldrich) to MEK (manufactured by Samchun Chemical) as a solvent, BYK-163 of BYK Corporation containing a polymer copolymer having a pigment affinity group as a dispersant Or a nonionic surfactant, Pluronic's F127 was added. Then, graphene powder (Six Element) or MWNT (nanocyl) was added as a nano-carbon material and stirred for 20 minutes. After stirring, the stirred solution was mixed with zirconia beads and dispersed for 80 minutes using a mixer to prepare a composition. The content of each component is shown in the table below.

Nano carbon (wt%) MEK (wt%) Binder (wt%) Dispersant (wt%) Copper phthalocyanine tetrasulfonic acid tetrasodium salt (wt%) Example 1 2.0 (graphene) 67.1 30.0 0.3 (BYK-163) 0.6 Example 2 2.0 (graphene) 66.8 30.0 0.6 (BYK-163) 0.6 Example 3 2.0 (graphene) 63.8 30.0 3.6 (BYK-163) 0.6 Example 4 2.0 (graphene) 65.4 30.0 0.6 (BYK-163) 2.0 Example 5 2.0 (MWNT) 66.8 30.0 0.6 (BYK-163) 0.6 Comparative Example 1 2.0 (graphene) 68.0 30.0 - - Comparative Example 2 2.0 (graphene) 60.8 30.0 7.2 (F127) - Comparative Example 3 2.0 (graphene) 60.8 30.0 7.2 (BYK-163) - Comparative Example 4 2.0 (graphene) 64.4 30.0 3.6 (BYK-163) - Comparative Example 5 2.0 (graphene) 66.2 30.0 1.8 (BYK-163) - Comparative Example 6 2.0 (graphene) 62.0 30.0 - 6.0 Comparative Example 7 2.0 (graphene) 66.0 30.0 - 2.0 Comparative Example 8 2.0 (graphene) 67.4 30.0 - 0.6

(Evaluation of properties of nano-carbon coating composition)

The prepared composition was printed on PET film with an automatic coater and a bar-coater, dried in a hot air oven at 80° C. for 1 minute, and then the sheet resistance was measured using a sheet resistance measuring instrument (SIMCO, ST-4).

For the chemical resistance test, after soaking for 5 minutes using isopropyl alcohol, a 1 kg weight was placed on it, and the change in sheet resistance was observed after 20 rubbing tests.

For dispersion stability, which is a property that the composition can be maintained without sedimentation of internal solids even during long-term storage, the composition is laid down horizontally and centrifugal force is applied to induce sedimentation. It was evaluated through an analyzer (Dispersion Analyzer, Lumisizer LS610). The higher the permeability, the more severe sedimentation of the nano-carbon material occurred, so it could be determined that the dispersion stability was not good.

In addition, in order to evaluate the flowability and dispersibility of the composition, the viscosity at 50 rpm was measured using a viscometer, and T.I (Thixotropic Index) was analyzed.

sheet resistance
(log,Ω/□) Chemical resistance evaluation
(log,Ω/□) dispersion stability
Transmittance (%) Viscosity
(50rpm) T.I. Example 1 3.6 10 ^3.6 70 51 2.9 Example 2 3.6 10 ^3.7 70 51 2.9 Example 3 3.6 10 ^4.0 70 48 2.8 Example 4 4.0 10 ^4.0 70 49 2.8 Example 5 4.3 10 ^4.3 72 40 2.0 Comparative Example 1 Characterization impossible due to solid-liquid separation Comparative Example 2 Characterization impossible due to the presence of a large amount of aggregates Comparative Example 3 5.3 10 ^13.5 87 125 5.2 Comparative Example 4 6.5 10 ^9.5 95 185 7.1 Comparative Example 5 7.1 10 ^8.4 100 320 10.9 Comparative Example 6 3.6 10 ^3.8 75 78 3.9 Comparative Example 7 4.0 10 ^4.2 77 82 3.6 Comparative Example 8 5.2 10 ^5.5 79 83 3.6

In the case of not adding a dispersing agent and a phthalocyanine compound (Comparative Example 1), solid-liquid separation occurred after the dispersion process, making characteristic evaluation impossible, and when F127 of Pluronic, a nonionic surfactant, was used as a dispersant (Comparative Example) 2) was impossible to characterize because there were many undispersed aggregates.

Comparative Examples 3 to 5 used BYK-163, a polyurethane-based dispersant including a polymer copolymer having a pigment affinity group as a dispersant.

In Comparative Examples 6 to 8, only the phthalocyanine compound was used without a dispersing agent. Although the sheet resistance and chemical resistance were excellent, the viscosity and T.I were maintained at high levels, and the permeability was somewhat high, resulting in poor dispersion stability and poor process applicability.

Examples 1 to 4 are cases in which a dispersing agent and a phthalocyanine compound are used together. It shows excellent sheet resistance and chemical resistance compared to Comparative Examples, and is judged to have excellent dispersion stability due to low transmittance. In addition, the viscosity and T.I were also maintained at low levels, indicating excellent process applicability.

Example 5 is a result of applying MWNT instead of graphene as a nano-carbon material. As in Examples 1 to 4, excellent sheet resistance, chemical resistance, and dispersion stability were exhibited, and the viscosity and TI were maintained at lower levels. This was thought to be because the specific surface area of the MWNT 300m ² / g to yes lower than the pin surface area 400m ² / g of.

Claims (10)

A nano-carbon coating composition comprising a nano-carbon material, a thermosetting binder, a dispersant, a phthalocyanine compound including sulfate, and a solvent. According to claim 1,
The nano-carbon material is at least one selected from the group consisting of graphene nano platelet (GNP), reduced graphene oxide (rGO), CNT, and carbon black, nano-carbon coating composition. 3. The method of claim 2,
The phthalocyanine compound containing the sulfate is copper phthalocyanine-tetrasulfonic acid tetrasodium salt, nickel phthalocyanine-tetrasulfonic acid tetrasodium salt, phthalocyanine tetrasulfonate tetrasodium salt ) at least one selected from the group consisting of, a nano-carbon coating composition. According to claim 1,
The size of the phthalocyanine compound is 1 ~ 100nm, nano-carbon coating composition. According to claim 1,
A nano-carbon coating composition comprising 0.001 to 5.0% by weight of the phthalocyanine compound based on the total composition. According to claim 1,
The solvent is MEK (Methyl Ethyl Ketone), n-butyl acetate (n-Butyl Acetate), EA (Ethyl Acetate), IPA (Isopropyl Acetate), MIBK (Metyl Isobutyl Ketone), DMF (Dimethyl Formamide), PGMEA (Propylene Glycol) Methyl Ether Acetate), ethanol, at least one selected from the group consisting of water, nano-carbon coating composition. According to claim 1,
A nano-carbon coating composition comprising 0.01 to 40.0 wt % of the nano-carbon material based on the total composition. According to claim 1,
The dispersing agent includes a polymer block copolymer having a pigment affinity group, and the pigment affinity group is any one of cationic, anionic, nonionic, salt-like, nano-carbon coating composition. According to claim 1,
A nano-carbon coating composition comprising 0.001 to 10.0% by weight of the dispersant based on the total composition. A conductive ink comprising the nano-carbon coating composition according to any one of claims 1 to 8.

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