KR20130086772A - Manufacturing method for coating layer having graphene - Google Patents

Abstract

PURPOSE: A manufacturing method of a graphene-containing coating film is provided to manufacture a high hardness coating film by steadily support a graphene by a network which is formed by the interaction between a polymethylsilsesquioxane and a polydimethylsiloxane terminated by an epoxypropoxy propyl. CONSTITUTION: A manufacturing method of a coating film comprises a step of preparing a graphene, a polymethylsilsesquioxane, and a polydimethylsiloxane terminated by an epoxypropoxy propyl; a step of preparing a first solution by injecting the graphene into a first solvent; a step of preparing a second solution by dissolving the polymethylsilsesquioxane and the polydimethylsiloxane terminated by an epoxypropoxy propyl into a second solvent; a step of simultaneously spraying the first solution and second solution on a substrate; and a step of obtaining the coating film by drying the first solution and the second solution on the substrate. [Reference numerals] (AA) Prepare solid raw material; (BB) Prepare a first solvent and a second solvent; (CC) Manufacture a first solution and a second solution; (DD) Manufacture a coating/coating film

Description

Manufacturing method for coating layer containing graphene {Manufacturing method for coating layer having graphene}

The present invention relates to a method for producing a coating film containing graphene, and more particularly, to a method for producing a coating film containing graphene capable of forming a conductive coating film of high hardness.

Graphene is produced by the exfoliation of graphite, and is composed of sp2 hybrid bonds of carbon as a continuous chemical bond of carbon atoms. The production price is relatively lower than that of carbon nanotubes. On the other hand, graphene has high electrical and thermal conductivity and high mechanical properties, so it is expected to be a representative nanomaterial that can replace carbon nanotubes.

Meanwhile, in order to take advantage of various materials, there is a growing interest in composite materials in which materials are composited. New composite applications require easy fabrication of composites. For example, in order to utilize the composite material in the form of a film, a method for easily manufacturing the same is required.

In order to commercialize a composite having various advantages, it is urgent to develop a manufacturing method that can grasp the characteristics of the composite and express it efficiently, and can easily prepare a composite material exhibiting various physical properties corresponding to user requirements.

However, when various materials are combined to produce composites that exhibit the desired physical properties, interactions between the materials, such as unwanted side reactions, can often occur. In this case, there is a problem in that it is difficult to manufacture a film having desired physical properties using a single composite material.

In the following prior art document (Patent Document 1: KR2011-0016289A1), a graphene oxide or graphene carbon nanopane is used as a material, and chemically and physically dispersed therein, which is prepared by complexing a composite material using a dispersion. A carbon nanoplatelet composite is disclosed.

KR2011-0016289 A1

The present invention provides a method for producing a coating film containing graphene, which can produce a coating film having desired physical properties.

The present invention provides a method for producing a coating film containing graphene that can improve the thermal conductivity and electrical conductivity of the coating film.

The present invention provides a method for producing a coating film containing graphene that can improve the mechanical properties of the coating film.

A method for producing a coating film containing graphene according to an embodiment of the present invention, as a method for producing a coating film, polydimethylsiloxane (terminated with graphene, polymethylsilsesquioxane (PMSSQ) and epoxypropoxypropyl ( preparing an epoxypropoxypropyl-terminated polydimethylsiloxane; Dissolving the graphene in a first solvent to prepare a first solution; Preparing a second solution by dissolving the polymethyl siloxane terminated with ploymethylsilsesquioxane (PMSSQ) and epoxy propoxypropyl in a second solvent; Simultaneously spraying the first solution and the second solution onto a substrate; And obtaining a coating film by drying the first solution and the second solution sprayed on the substrate.

In this case, the graphene may be included in the range of 1 to 10% based on the total weight of the polydimethylsiloxane terminated with the polymethylsilsesquioxane and epoxypropoxypropyl.

The first solvent may contain graphene which is at least one of isopropyl alcohol (IPA), methyl isobutyl ketone (MethylIsoButylKetone), and ethanol.

The polymethylsilsesquioxane may contain graphene included in the range of 70 to 95% relative to the total weight of the polymethylsilsesquioxane and polydimethylsiloxane terminated with the epoxypropoxypropyl.

The second solvent is ethyl acetate, n-butyl acetate, n-buthy acetate, cyclohexanone, 1-pentanol, n-propanol, and It may also include at least one of 2-Ethoxyethyl acetate.

In the process of spraying the first solution and the second solution, the substrate may be heated.

The drying of the first solution and the second solution may be performed at the same temperature as that of the substrate in the process of spraying the first solution and the second solution.

Further drying after the drying of the first solution and the second solution may be further included. In this case, the additional drying process may be performed at a higher temperature than the drying of the first solution and the second solution.

According to the embodiment of the present invention, a graphene-containing coating film having excellent hardness can be produced. The coating film of high hardness can be manufactured by firmly supporting graphene through a network formed by the interaction of polymethylsilsesquioxane and polydimethylsiloxane terminated with epoxy propoxypropyl.

In addition, according to the embodiment of the present invention, the conductive coating film having excellent durability can be manufactured using the mechanical properties of the polydimethylsiloxane terminated with polymethylsilsesquioxane and epoxypropoxypropyl. This can improve the durability of the product applying the coating film prepared by the present invention.

1 is a process flow diagram of manufacturing a coating film by a method for producing a coating film containing graphene according to an embodiment of the present invention.
Figure 2 is an electron micrograph of the coating film prepared according to the experimental example of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know.

1 is a process flowchart of a composite material manufacturing method according to an embodiment of the present invention.

Referring to Figure 1, the method for producing a coating film containing graphene according to an embodiment of the present invention, polydimethylsiloxane terminated with graphene, polysilsesquioxane and epoxy propoxypropyl (polydimethylsiloxane, hereinafter E- PDMS), preparing the first and second solvents, dissolving graphene in the first solvent to prepare a first solution, polysilsesquioxane and E-PDMS The process includes preparing a second solution by dissolving in a solvent, forming a coating film by coating the first solution and the second solution on a substrate, and drying the coating film.

First, prepare raw materials. That is, graphene, polysilsesquioxane and E-PDMS, and a solvent to dissolve them are prepared, respectively.

Graphene is a carbon nanomaterial with one layer of graphite stripped off. In other words, graphite has a structure in which carbon layers are stacked in a hexagonal honeycomb shape, and graphene may be regarded as the thinnest layer of graphite. Graphene, a carbon allotrope, is a nanomaterial composed of carbon number 6, such as carbon nanotubes and fullerenes. It has a two-dimensional planar shape, and its thickness is 0.2nm (1nm is 1m / 1 billion) or 2m / 10 billion, which is extremely thin and has high physical and chemical stability. It is 100 times more electricity than copper, and can transfer electrons 100 times faster than single crystal silicon, which is mainly used as a semiconductor. The strength is more than 200 times stronger than steel, and more than twice the thermal conductivity of diamond, which boasts the highest thermal conductivity. In addition, it has excellent elasticity and does not lose its electrical properties even when stretched or bent. Due to these characteristics, graphene is being evaluated as a material that exceeds carbon nanotubes, which is emerging as a next-generation new material, and is more likely to be applied industrially because it has a uniform metallicity than carbon nanotubes. In addition, graphene is attracting attention as a future new material in the electronic information industry that can make bendable displays, electronic paper, wearable computers and the like. In the present embodiment, the graphene was prepared by releasing graphite into discrete graphene by ultrasonic treatment after loosening the interlayer bond with strong acid. In addition, the graphene may also be prepared as exfoliated graphene by thermal expansion at a high temperature.

The production of graphene in the present embodiment was performed by modifying the method of Hummers (Hummers).

First, the graphite is heat-treated in an argon atmosphere at 500 ° C. to remove impurities.

Next, 5 g of powdered flake graphite and 2.5 g of sodium nitrate (NaNO ₃ ) are added to a container containing 100 ml of sulfuric acid (H ₂ SO ₄ ), and then the mixed solution is stirred for 20 to 40 minutes. At this time, it is preferable to put the vessel in a reaction tank of about 0 ℃ for safe reaction.

While the mixture is stirred, 15 g of potassium permanganate (KMnO ₄ ) is added to the vessel. At this time, potassium permanganate is added in small amounts of about 0.1g over several dozen turns. As a result, the temperature rise can be suppressed by the mixed liquid in the container reacting rapidly with potassium permanganate.

Then, the reaction tank is removed, and when the temperature of the mixed liquid reaches 32 ° C to 38 ° C, it is maintained in this state for 30 minutes. At this time, after 20 minutes, the gas and bubbles generated while the mixed solution reacts are removed to form a viscous reactant. The reactant thus formed reaches a paste state and is grayish brown. After 30 minutes, 250 ml of distilled water is added into the vessel containing the reaction and stirred slowly. At this time, vigorous boiling and temperature increase up to 98 ° C. are accompanied, and the reactant becomes brown. The reaction is held for 15 minutes after stirring.

Thereafter, 700 ml of distilled water at 40 ° C. is further added to the vessel and diluted, and a small amount of 30% hydrogen peroxide is added to reduce permanganate and manganese dioxide generated during the reaction. The reaction turns bright yellow due to the addition of hydrogen peroxide. The diluted reactant was filtered using a filter having a pore size of 5 μm to obtain a yellowish-brown cake-like result, that is, graphite oxide.

The resulting product is washed at least three times with 250 ml of distilled water. At this time, when the pH of the waste water reaches neutral around 7, the washing process is completed.

Thereafter, the graphite oxide is diluted in distilled water at a concentration of 1 g / L, and sonicated for 1 to 2 hours to break the weakened interlayer bonding layer of graphite oxide into a graphene oxide state. Then, 1 ml of hydrazine hydrate per 100 mg of graphite oxide was further added and refluxed for 24 hours to obtain reduced graphene. Subsequently, the reduced graphene is washed with distilled water and methanol, followed by drying to obtain graphene in powder form. The method for producing graphene is not particularly limited to the method presented herein, and may be prepared by various methods.

Polymethylsilsesquioxane (PMSSQ) and E-PDMS are materials used as a support for supporting graphene in the coating film. Polymethyl silsesquioxane has the following structure _{(H 3 CSiO 1 .5) n} [ Formula 1] below and the empirical formula of the.

Polymethylsilsesquioxane has been studied as an electrical insulator at high temperatures since the first commercialization of silicone polymers. In particular, polymethylsilsesquioxane has a low dielectric constant of about 2.7 to 2.9, and is well known as an electrical insulator because of its low water absorption, high thermal stability and relatively high mechanical properties that can withstand high temperatures of 450 ° C or higher. . In addition, the polysilsesquioxane may affect the electrical insulating properties and mechanical properties of the insulator thin film obtained through the reaction of hydroxyl group (-OH) with other materials at the end.

Since E-PDMS is homogeneous and isotropic, it is optically transparent up to a thickness of 300 nm. Therefore, this property can be used to make an optical device. In addition, PDMS is a very durable elastomer and has adhesion to the substrate. In addition, PDMS is transparent and chemically stable, excellent in chemical resistance and excellent in heat resistance, making it easy to use for high hardness thin film coating. E-PDMS has a structure as shown in [Formula 2]. E-PDMS has a structure as shown in [Formula 2].

In an embodiment of the present invention, the hydroxyl group (-OH) at the end of the polymethylsilsesquioxane and the ring-opened epoxide at the end of the E-PDMS react with each other and crosslinked to form a network. Through such a structure, the graphene can be firmly supported to form a conductive coating film of high hardness.

The first solvent may be at least one of isopropyl alcohol (IPA), methyl isobutyl ketone (MethylIsoButylKetone) and ethanol (ethanol) having solubility in graphene. These solvents may be used alone or in a proportion of the mixed solution.

As the second solvent, a material having solubility in polymethylsilsesquioxane and E-PDMS may be used, and ethyl acetate, n-butyl acetate, cyclohexanone, At least one of 1-pentanol, n-propanol, and 2-Ethoxyethyl acetate may be used.

Once the raw materials are prepared, each solid raw material (graphene, polymethylsilsesquioxane, E-PDMS) is completely dissolved in each solvent to bring it into solution. Graphene is added to the first solvent and completely dissolved to prepare a first solution. At this time, the first solution is added to the desired amount of powdered graphene in a first solvent, that is, a first solvent having solubility in the graphene presented above and completely dissolved to form a first solution. In addition, the desired amount of polymethylsilsesquioxane and E-PDMS is added to a second solvent, ie the second solvent set forth above, and completely dissolved to form a second solution. At this time, each solution may be prepared by stirring or applying ultrasonic waves for a sufficient time so that each solid raw material is completely dissolved in each solvent and sufficiently sprayed.

The solid weight in the first solution and the second solution thus formed may be changed in various ways depending on the intended use and required physical properties. For example, in order to increase the electrical conductivity of the coating film, the content of graphene may be increased to prepare a first solution. In addition, the second solution may be prepared by increasing the content of polymethylsilsesquioxane in order to increase the mechanical properties of the coating film, that is, the strength, and increasing the content of E-PDMS in order to improve the adhesion of the coating film.

In addition, the ratio of graphene to polymethylsilsesquioxane and E-PDMS in each solution can be variously changed according to required physical properties. For example, graphene may be in a range of 1 to 10% with respect to the total weight of polymethylsilsesquioxane and E-PDMS when the total weight of polymethylsilsesquioxane and E-PDMS is 100%. If the amount of graphene is too small, the characteristics of graphene, such as conductivity, are not expressed. If the amount of graphene is too large, the characteristics of graphene, such as conductivity, are no longer improved, and polymethylsilsesquioxane and E-PDMS Excellent characteristics, such as thermal conductivity and high hardness, which have, are reduced.

In addition, the ratio of polymethylsilsesquioxane and E-PDMS can be variously changed according to required physical properties. For example, when the total weight of polymethylsilsesquioxane and E-PDMS is 100%, the polymethylsilsesquioxane is preferably in the range of 70 to 95% by weight. When the amount of polymethylsilsesquioxane is too small, the adhesion of the formed coating film is increased while the surface strength is low. When the amount of polymethylsilsesquioxane is too high, the surface strength of the coating film is high while the adhesion of the coating film is high. Will be lowered. In addition, when the amount of polymethylsilsesquioxane is too large, the hardness is high, there is also a problem that is easily damaged by external impact and stress.

The first solution and the second solution are used for spray coating. When the content of the solid raw material added to each solvent is too low, the drying process performed after the spray coating, that is, the time required to remove the solvent, takes a long time. It becomes long, and thus there is a problem that the process efficiency is lowered. In addition, when the content of the solid raw material is too high, the viscosity of the solution is increased to cause clogging of the fine nozzle, the spray coating process itself is interrupted or the opening and closing of the nozzle irregularly during the process may cause a problem of uneven film quality It may be. Therefore, in the case of the first solution, the graphene content is 0.1 to 5% by weight, and in the case of the second solution, the polymethylsilsesquioxane and E-PDMS are 1 to 20% by weight. It is advantageous to apply.

Using the first solution and the second solution prepared as described above to prepare a high hardness conductive coating film. A substrate is prepared, and the first solution and the second solution are sprayed onto the substrate by spraying the substrate while heating the substrate at about 80 to 100 ° C. to prepare a coating film or a coating film. In this case, when the temperature is too high, the solvent may be rapidly evaporated, bubbles may occur in the coating film, and the quality of the coating film may be lowered, and the first and second solutions may not be homogeneously mixed, thereby reducing the quality of the coating film. In addition, when the temperature is too low, the solvent is not evaporated smoothly so that the solution sprayed onto the substrate forms droplets on the substrate, and the solid raw materials dispersed in the droplets move to the edge of the droplets to each other. As a result, there is a problem in that the distribution of solid raw materials in the coating film is uneven.

In this case, when the adhesion property between the substrate and the coating film is required, a metal material such as aluminum, steel, stainless steel, brass, titanium, or the like may be used as the substrate. In the case of using as a support, a glass or the like may be used that can easily peel off the coating film due to poor adhesion characteristics with the coating film. If necessary, the adhesion between the coating film and the substrate may be improved by surface treatment of the glass.

Subsequently, the coating film formed on the substrate is dried to obtain a high hardness conductive coating film. At this time, it is good to dry for 24 hours in a vacuum oven of about 80 to 100 ℃. There is a problem that the drying time is increased when the coating film is dried at a temperature lower than the suggested range, and when the coating film is dried at an excessively high temperature, there is a problem that the coating film may be deformed during the drying process. In addition, if necessary, it may be further vacuum-dried for 1 to 3 hours in a vacuum oven of about 100 to 200 ℃. In this way, the drying process may further reduce the surface roughness of the coating film or realign the coating film such as removing residual solvent in the coating film, and increase the hardness of the coating film to improve mechanical properties. When the additional drying process is performed for a time shorter than the suggested range, the above-mentioned effects cannot be realized, and when the time is performed for a longer time than the suggested range, the above-mentioned effects are insignificant. Therefore, it is better to manufacture a high quality coating film efficiently by performing an additional drying process within the suggested range.

In the following, specific experimental examples will be described. The coating film was formed using the method described above.

First, the first solution was prepared in four types so that the graphene concentration was 0%, 1%, 3%, and 5%, respectively. At this time, ethanol was used as the first solvent, the graphene concentration of 0% in the first solution was not added to the graphene.

The second solution was prepared to have a polymethylsilsesquioxane and E-PDMS concentration of 10%. At this time, ethyl acetate was used as the second solvent, and polymethylsilsesquioxane to E-PDMS was used in a weight ratio of 70:30.

Thereafter, 16 substrates were prepared, 0 wt% of the first solution and the second solution (samples 1 to 4) were prepared on four substrates, and 1 wt% of the first solution and the second solution (sample 5 were prepared on the four substrates). 8), 3 wt% of the first solution and the second solution (samples 9 to 12) on the four substrates, and 5 wt% of the first solution and the second solution (samples 13 to 16) on the remaining four substrates. 4 types of samples were prepared by spraying. At this time, the spray of the solution may be used by any method of pneumatic and electrospray, in this experiment, the first solution and the second solution were sprayed using the electrospray. In this experiment, a glass substrate was used as a substrate, but substrates of various materials such as polymer, metal, ceramic, and the like may be used. At this time, the distance between the nozzle and the glass substrate to which the first solution and the second solution are injected is 5 cm, and a voltage of 5 kV was applied to the spray coating system. In addition, the first solution and the second solution were sprayed at a rate of 100 μl / min, and the total injection amount of the first solution and the second solution was adjusted to form a 0.5 μm coating film on the substrate. The substrate was heated to 80 ° C. while spraying the first and second solutions. After spraying the first solution and the second solution to form a coating film, the coating film was dried for 24 hours while maintaining the same temperature as when the substrate is sprayed with the first solution and the second solution.

Thereafter, three samples were further dried at 100 ° C. for 3 hours, 6 hours and 12 hours except for one of the samples prepared under the same conditions (the same graphene concentration of the first solution).

2 is an electron micrograph of the coating film prepared according to the experimental example of the present invention.

Looking at the picture of Figure 2 it can be seen that the graphene is evenly distributed to form a network.

The hardness and sheet resistance of the coating film thus prepared were investigated.

The hardness of the coating film was measured by a nanoindentation method, and the average value of the measured values at a total of 12 points is shown in [Table 1]. Here, nanoindentation is a method of evaluating mechanical properties such as hardness, modulus of elasticity, etc. by injecting an indenter with an attachment into a thin film with a load of several mN and deforming the thin film to a nanometer scale. The elastic modulus and hardness of the thin film can be calculated by measuring the load, the indentation depth of the indenter, and the time.

Additional drying time (hr) 0 3 6 12
Concentration of the first solution 0% by weight 1.11 1.75 1.75 1.80 1 wt% 1.02 1.40 1.53 1.55 3 wt% 0.85 1.44 1.45 1.46 5 wt% 0.77 1.12 1.20 1.21

Looking at [Table 1], it can be seen that the hardness of the coating film is lowered as the graphene content increases. This is because the hardness of the coating film is lowered because the content of polymethylsilsesquioxane and E-PDMS in the coating film decreases as the graphene content increases. In addition to the additional drying time, the additional drying time is shown to increase the hardness of the coating film significantly up to 3 hours, it can be seen that the increase in hardness is less than 3 hours.

Table 2 below shows the measurement results of the sheet resistance of the coating film.

Additional drying time (hr) 0 3 6 12 Concentration of the first solution One% 15.0 16.2 16.1 16.2 3% 9.7 10.0 9.9 10.0 5% 3.9 4.2 4.2 4.2

Referring to [Table 2], it can be seen that the higher the graphene concentration in the coating film, the lower the sheet resistance. This means that the higher the graphene concentration, the higher the conductivity of the coating layer. Further, when the coating film is further dried up to 3 hours, the sheet resistance is significantly increased. However, when the coating layer is further dried, the sheet resistance is insignificant. This is determined by the change in the distance between the graphene before and after the coating film is completely dried, and almost no change in the sheet resistance after the coating film is completely dried.

As mentioned above, although this invention was demonstrated with reference to the above-mentioned embodiment and an accompanying drawing, this invention is not limited to this, It is limited by the following claims. Therefore, it will be apparent to those skilled in the art that the present invention may be variously modified and modified without departing from the technical spirit of the following claims.

Claims (9)

As a manufacturing method of the coating film,
Preparing an epoxypropoxypropyl-terminated polydimethylsiloxane terminated with graphene, polymethylsilsesquioxane (PMSSQ) and epoxypropoxypropyl;
Dissolving the graphene in a first solvent to prepare a first solution;
Preparing a second solution by dissolving the polymethyl siloxane terminated with ploymethylsilsesquioxane (PMSSQ) and epoxy propoxypropyl in a second solvent;
Simultaneously spraying the first solution and the second solution onto a substrate; And
Obtaining a coating film by drying the first solution and the second solution sprayed on the substrate;
Method for producing a coating film containing a graphene containing a. The method according to claim 1,
The graphene is a method for producing a coating film containing graphene contained in the range of 1 to 10% based on the total weight of the polydimethylsilsesquioxane and polydimethylsiloxane terminated with epoxy propoxypropyl. The method according to claim 1,
The first solvent is isopropyl alcohol (IsoPropyl Alcohol; IPA), methyl isobutyl ketone (MethylIsoButylKetone) and ethanol (ethanol) at least any one of the manufacturing method of the coating film containing a graphene. The method according to claim 1,
The polymethylsilsesquioxane is a graphene-containing coating film prepared in the range of 70 to 95% based on the total weight of the polymethylsilsesquioxane and polydimethylsiloxane terminated with the epoxy propoxypropyl. Way. The method according to claim 2,
The second solvent is ethyl acetate, n-butyl acetate, n-buthy acetate, cyclohexanone, 1-pentanol, n-propanol, and A method for producing a coating film containing graphene containing at least one of 2-ethoxyethyl acetate. The method according to claim 1 or 2,
In the process of spraying the first solution and the second solution,
Method for producing a coating film containing graphene for heating the substrate. The method according to claim 3,
Drying of the first solution and the second solution,
A method of manufacturing a coating film containing graphene is carried out at the same temperature as the temperature of the substrate in the process of spraying the first solution and the second solution. The method according to claim 3,
Method of producing a coating film containing a graphene further comprising a further drying process after the drying of the first solution and the second solution. The method according to claim 8,
The further drying process is a method for producing a coating film containing graphene is carried out at a higher temperature than the drying of the first solution and the second solution.

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