A kind of high temperature resistant graphene conductive ink and preparation method thereof

Abstract

The present invention relates to a high-temperature resistant graphene conductive ink, which is composed of graphene-coated glass powder, a water-soluble resin, a dispersant, a leveling agent, a defoaming agent, and water. The graphene in the graphene-coated glass powder has a thickness of 1 nm to 10 nm, a graphene flake diameter of 1 μm to 40 μm, and a mass proportion of graphene of 5 to 20%. The particle size of the glass powder is 1 μm to 20 μm. Compared with traditional graphene conductive inks, the present invention adopts the graphene-coated glass powder as a conductive filler, so that the ink has smaller square resistance, better conductivity, forms a good conductive network, and is not easy to agglomerate.

Description

Technical Field

[0001] The present invention relates to the technical field of graphene conductive inks, and in particular to a water-based, high-temperature-resistant graphene conductive ink. Background Art

[0002] Currently, conductive inks on the market are generally categorized into low-temperature, medium-temperature, and high-temperature conductive inks. Low- and medium-temperature conductive inks typically consist of conductive composites composed of conductive particles (gold, silver, copper, and carbon black) uniformly dispersed in a polymer binder. These conductive inks have a maximum temperature resistance of no more than 200°C, making them unsuitable for many high-temperature applications.

[0003] High-temperature conductive inks are typically made from precious metals like gold, silver, and platinum, and glass powder, sintered at high temperatures to form a conductive composite material. However, precious metals are expensive and subject to significant price fluctuations in the international market. Another common method for preparing high-temperature conductive inks is to mix glass powder with an inorganic binder to create a conductive paste. However, while this conductive ink is heat-resistant, its sheet resistance is too high, significantly compromising its conductivity. Therefore, there is a need to develop a low-cost, environmentally friendly conductive oil ink that can be sintered onto substrates like stainless steel and ceramics, capable of long-term use below 600°C, with high heat generation, low energy consumption, and minimal degradation over time.

[0004] Graphene has excellent electrical and thermal conductivity and stability, making it a promising filler for high-temperature conductive inks. However, due to its large surface area, graphene easily aggregates and is difficult to disperse within the system. This prevents the full utilization of its excellent electrical conductivity, affecting the physical properties and printability of the conductive ink.

[0005] Therefore, how to improve the conductivity of graphene in conductive ink and make it easy to disperse evenly in the resin system is a key issue in the current field of graphene conductive ink. Summary of the Invention

[0006] To address the above technical issues, the first objective of the present invention is to provide a high-temperature resistant graphene conductive ink comprising graphene-coated glass powder, a water-soluble resin, a dispersant, a leveling agent, a defoaming agent, and water. The graphene in the graphene-coated glass powder has a thickness of 1 nm to 10 nm, a flake diameter of 1 μm to 40 μm, and a mass fraction of 5 to 20%. The glass powder has a particle size of 1 μm to 20 μm. The graphene flake diameter is larger than the particle size of the glass powder, enabling complete coverage of the glass powder by the graphene.

[0007] Furthermore, the glass frit comprises the following components by mass: 30-55% SiO2, 10-35% Al2O3, 5-15% ZnO, 3-5% MgO, and 1-5% SnO2. The melting range of the glass frit is 500-700°C. The doping of Al2O3, ZnO, MgO, and SnO2 is intended to form an amorphous phase eutectic, thereby adjusting the melting range. The 500-700°C melting range of the glass frit is selected to ensure the quality of subsequent high-temperature-resistant conductive ink products. If the ink fails to sinter, melt, and then solidify at temperatures above 700°C, the graphene may oxidize in air, causing product degradation.

[0008] Furthermore, the mass ratio of the graphene-coated glass powder, water-soluble resin, dispersant, leveling agent, defoaming agent and pure water is (200-500):(100-300):(1-10):(20-70):(0.2-3):(100-300).

[0009] Furthermore, the water-soluble resin is one or more of a water-based acrylic resin, a water-based polyester resin, or a water-based polyurethane resin; the dispersant is one or more of a carboxylate dispersant, an aliphatic amide dispersant, and an ester dispersant; the leveling agent is one or more of polyacrylic acid and polyether-modified polysiloxane; and the defoaming agent is one or more of mineral oil and silicone. The water-soluble resin, dispersant, and leveling agent are added to ensure that the high-temperature-resistant conductive ink can be coated into a film.

[0010] The second object of the present invention is to provide a method for preparing high-temperature resistant graphene conductive ink.

[0011] Graphene-coated glass powder is prepared, and the graphene-coated glass powder, a water-soluble resin, a dispersant, a leveling agent, a defoaming agent, and water are mixed and stirred uniformly, and then ground to obtain a water-based, high-temperature-resistant graphene conductive ink.

[0012] Furthermore, the graphene-coated glass powder is prepared in the following steps: S1: mixing glycogen, graphene oxide and water; S2: adding glass powder to the glycogen and graphene oxide aqueous solution and stirring evenly; S3: adding the above substances to a hydrothermal reactor, performing a reduction reaction at a temperature of 200-400°C and a pressure of 123KPa-309KPa for 4h-12h, filtering through a 100-400 mesh filter, and baking at 100-200°C for 30-120min to obtain graphene-coated glass powder.

[0013] Furthermore, the glycogen includes at least one of glucose, fructose, lactose, sucrose, and starch, and the mass ratio of glycogen, graphene oxide, and water in step S1 is (5-20):(0.5-4):100.

[0014] Furthermore, in step S2, the mass ratio of the glycogen and graphene oxide aqueous solution to the glass powder is 100:(10-30).

[0015] Furthermore, the grinding process is as follows: grinding 3 to 5 times using a three-roll grinder, and the slurry fineness is controlled to be below 20 μm.

[0016] The third object of the present invention is to provide an application method of high temperature resistant graphene conductive ink.

[0017] After coating the aforementioned high-temperature-resistant graphene conductive ink or the high-temperature-resistant graphene conductive ink prepared by the aforementioned method, the ink is sintered and cured in stages. The first stage is sintered at a temperature of 80-150°C for 10-30 minutes; the second stage is sintered at a temperature of 200-350°C for 10-30 minutes; and the third stage is sintered at a temperature of 400-650°C for 10-30 minutes. The ink is then cooled to room temperature to complete the curing process. The reasons for using the staged sintering method are as follows: the first sintering stage removes water from the conductive ink; the second sintering stage removes non-practical substances such as resin from the ink, as residual resin and other substances will ultimately weaken the ink's conductivity; the third sintering stage melts the glass powder, which then re-solidifies on a substrate such as stainless steel or ceramic after cooling.

[0018] The beneficial effects of the present invention are:

[0019] 1. In the present invention, a glycogen substance is added during the graphene-coated glass powder process. The glycogen substance contains hydroxyl groups that can form hydrogen bonds with the glass powder. This not only facilitates the dispersion of the glass powder, but also creates steric hindrance by binding to the glass powder, thereby adjusting the ratio of graphene oxide to the glass powder, thereby regulating the degree of graphene coating and the thickness of the glass powder. Furthermore, the glycogen substance can also serve as a carbon source, synergistically interacting with the graphene oxide to enhance the graphene coating of the glass powder. The present invention prepares the graphene-coated glass powder via a hydrothermal method. The glycogen substance and graphene oxide bind to the glass powder via hydrogen bonding, allowing the carbon source to uniformly coat the glass powder, thereby forming a graphene layer of uniform thickness on the surface of the glass powder. Specifically, the graphene layer has a thickness of 1 nm to 10 nm and a flake diameter of 1 μm to 40 μm. The graphene layer is structurally complete and defect-free. Compared to graphene-coated glass powder prepared by BCVD, the present invention's preparation method is simpler and results in more uniform graphene coating.

[0020] 2. Compared with traditional high-temperature resistant graphene conductive ink, the present invention uses graphene-coated glass powder as a conductive filler, which makes the ink have smaller square resistance, better conductivity, forms a good conductive network, and is not easy to agglomerate.

[0021] 3. Compared with traditional conductive inks, the conductive ink provided by the present invention has the characteristic of high temperature resistance. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solution in conjunction with the embodiments of the present invention. Obviously, the embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention. Example 1

[0023] This embodiment provides a high-temperature resistant graphene conductive ink, the preparation method of which is as follows:

[0024] (1) Preparation of graphene-coated glass powder. The preparation steps are as follows: S1: Mix glycogen, graphene oxide, and water in a certain proportion; S2: Add a certain proportion of glass powder to the glycogen and graphene oxide aqueous solution and stir evenly; S3: Add the above substances into a hydrothermal reactor, perform a reduction reaction at a temperature of 230°C and a pressure of 200 kPa for 8 hours, filter through a 200-mesh filter, and bake at 100°C for 60 minutes to obtain graphene-coated glass powder, wherein the graphene in the graphene-coated glass powder has a thickness of 1 nm to 10 nm, a graphene sheet diameter of 1 μm to 40 μm, and a mass proportion of graphene of 10%.

[0025] The glycogen is starch; the sheet diameter of the graphene oxide is 1 μm to 40 μm, the thickness is 1 nm to 5 nm, and the ratio of carbon to oxygen substances is 1.5:1; the mass ratio of the glycogen, graphene oxide and water is 10:0.8:100.

[0026] The melting range of the glass powder is 500~700℃; the glass powder includes the following components in mass percentage: 50% SiO2, 28% Al2O3, 13% ZnO, 5% MgO, and 4% SnO2; the particle size of the glass powder is 10μm; the mass ratio of the glycogen and graphene oxide aqueous solution to the glass powder is 100:20.

[0027] (2) Add 200 parts of pure water and 5 parts of dispersant into the dispersion tank in the order of mass ratio, and stir at 800 r / min for 10 min using a planetary mixer;

[0028] Then, 400 parts of the prepared graphene-coated glass powder was added and stirred at 1000 r / min for 15 min;

[0029] Then add 300 parts of water-soluble resin and 50 parts of leveling agent, and stir at 2000 r / min for 25 minutes;

[0030] Finally, 0.5 parts of defoaming agent was added and stirred at 1000 r / min for 10 minutes.

[0031] The water-soluble resin is a water-based acrylic resin.

[0032] The dispersant is sodium carboxymethyl cellulose.

[0033] The leveling agent is polyether-modified polysiloxane.

[0034] The defoaming agent is selected from mineral oil.

[0035] (3) Grinding the mixed slurry prepared in step (2) using a three-roll grinder for 5 times, and controlling the slurry fineness to be below 20 μm, thereby obtaining a water-based, high-temperature resistant graphene conductive ink.

[0036] The water-based, high-temperature-resistant graphene conductive ink prepared by the above steps can be used by screen printing.

[0037] The graphene conductive ink prepared by the above steps is sintered in stages when used. The first stage is sintered at a temperature of 100°C for 15 minutes; the second stage is sintered at a temperature of 300°C for 30 minutes; the third stage is sintered at a temperature of 600°C for 15 minutes; and then cooled to room temperature to complete the solidification. Example 2

[0038] The difference between Example 2 and Example 1 is that in step (1), the mass ratio of the glycogen and graphene oxide aqueous solution to the glass powder is 100:25, and the other steps are consistent with Example 1. Example 3

[0039] The difference between Example 3 and Example 1 is that the mass ratio of glycogen, graphene oxide and water in step (1) is 5:1:100, and the other steps are consistent with Example 1. Example 4

[0040] The difference between Example 4 and Example 1 is that step (2) is as follows:

[0041] Add 200 parts of pure water and 5 parts of dispersant to the dispersion tank in the order of mass ratio, and stir at 800 r / min for 10 minutes using a planetary mixer;

[0042] Then, 500 parts of the prepared graphene-coated glass powder was added and stirred at 1000 r / min for 15 min;

[0043] Then add 300 parts of water-soluble resin and 50 parts of leveling agent, and stir at 2000 r / min for 25 minutes;

[0044] Finally, 0.5 parts of defoaming agent was added and stirred at 1000 r / min for 10 minutes.

[0045] The water-soluble resin is a water-based acrylic resin.

[0046] The dispersant is sodium carboxymethyl cellulose.

[0047] The leveling agent is polyether-modified polysiloxane.

[0048] The defoaming agent is selected from mineral oil.

[0049] That is, 500 parts of graphene-coated glass powder were added, and the remaining steps were the same as those in Example (1). Comparative Example 1

[0050] The difference between this comparative example and Example 1 is that no glycogen is added during the process of graphene-coated glass powder:

[0051] (1) Preparation of graphene-coated glass powder. The preparation steps are as follows: S1: Mixing graphene oxide and water in a certain proportion; S2: Adding a certain proportion of glass powder to the graphene oxide aqueous solution and stirring evenly; S3: Adding the above substances into a hydrothermal reactor, reducing the reaction at a temperature of 230°C and a pressure of 200 kPa for 8 hours, filtering through a 200-mesh filter, and drying at 100°C for 60 minutes to obtain graphene-coated glass powder, wherein the graphene in the graphene-coated glass powder has a thickness of 30-50 nm, a sheet diameter of 1 μm-40 μm, and a mass proportion of graphene of 30%.

[0052] The graphene oxide has a sheet diameter of 1 μm to 40 μm, a thickness of 1 nm to 5 nm, a carbon-oxygen mass ratio of 1.5:1, and a mass ratio of the graphene oxide to water of 0.8:100.

[0053] The glass powder includes the following components in mass percentage: 50% SiO2, 28% Al2O3, 13% ZnO, 5% MgO, and 4% SnO2; the particle size of the glass powder is 10 μm; the mass ratio of the glycogen and graphene oxide aqueous solution to the glass powder is 100:20.

[0054] (2) Add 200 parts of pure water and 5 parts of dispersant into the dispersion tank in the order of mass ratio, and stir at 800 r / min for 10 min using a planetary mixer;

[0055] Then, 400 parts of the prepared graphene-coated glass powder was added and stirred at 1000 r / min for 15 min;

[0056] Then add 300 parts of water-soluble resin and 50 parts of leveling agent, and stir at 2000 r / min for 25 minutes;

[0057] Finally, 0.5 parts of defoaming agent was added and stirred at 1000 r / min for 10 minutes.

[0058] The water-soluble resin is a water-based acrylic resin.

[0059] The dispersant is sodium carboxymethyl cellulose.

[0060] The leveling agent is polyether-modified polysiloxane.

[0061] The defoaming agent is selected from mineral oil.

[0062] The mixed slurry prepared in step (2) is ground 5 times using a three-roll grinder, and the slurry fineness is controlled to be below 20 μm, thereby obtaining a water-based, high-temperature resistant graphene conductive ink. Comparative Example 2

[0063] The difference between this comparative example and the embodiment is that the graphene-coated glass powder in Example 1 is replaced with reduced graphene oxide and glass powder, that is, the glass powder is not subjected to graphene coating treatment.

[0064] (1) Add 200 parts of pure water and 5 parts of dispersant in the dispersion tank in the order of mass ratio, and stir at 800 r / min for 10 min using a planetary mixer;

[0065] Then, 40 parts of the prepared reduced graphene oxide and 360 parts of glass powder were added and stirred at 1000 r / min for 15 min;

[0066] Then add 300 parts of water-soluble resin and 50 parts of leveling agent, and stir at 2000 r / min for 25 minutes;

[0067] Finally, 0.5 parts of defoaming agent was added and stirred at 1000 r / min for 10 minutes.

[0068] The water-soluble resin is a water-based acrylic resin.

[0069] The dispersant is sodium carboxymethyl cellulose.

[0070] The leveling agent is polyether-modified polysiloxane.

[0071] The defoaming agent is selected from mineral oil.

[0072] The mixed slurry prepared in step (1) was ground 5 times using a three-roll grinder, and the slurry fineness was controlled to be below 20 μm, thereby obtaining graphene conductive ink.

[0073] The viscosity of the conductive inks in the above examples and comparative examples was tested according to JIS Z8803:2011. The coatings were cured on the same stainless steel substrate and then tested using a four-probe method with a 25 μm film thickness. The test indicators are shown in the following table:

[0074] Experimental groups Viscosity (dPa·S) Square resistance (Ω / □) Example 1 120 0.3 Example 2 110 0.5 Example 3 130 1.5 Example 4 160 2 Comparative Example 1 250 90 Comparative Example 2 400 600

[0075] From the comparison between Comparative Example 1 and Example 1, it can be seen that by removing the glycogen substance in the process of preparing the graphene-coated glass powder, the thickness of the graphene in the graphene-coated glass powder prepared in this way is increased, and the mass proportion of the graphene is increased, thereby making the viscosity higher and the square resistance also increased accordingly.

[0076] From the comparison between Comparative Example 2 and Example 1, it can be seen that the viscosity and square resistance of the conductive ink prepared by separating reduced graphene oxide and glass powder as conductive fillers are much greater than those of the conductive ink prepared by using graphene-coated glass powder as the conductive filler. The reason is that graphene as a conductive filler is difficult to disperse evenly in the system, the system viscosity is high, the square resistance is also high, and the conductivity is poor.

[0077] From the above comparison, it can be seen that the use of graphene-coated glass powder as conductive filler can solve the problem of graphene being easily dispersed and agglomerated in the system. The prepared graphene conductive ink has moderate viscosity and low sheet resistance.

[0078] The above description is a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A high temperature resistant graphene conductive ink, characterized in that: The invention relates to a graphene-coated glass powder, a water-soluble resin, a dispersant, a leveling agent, a defoaming agent and water. The graphene in the graphene-coated glass powder has a thickness of 1 nm to 10 nm, a sheet diameter of 1 μm to 40 μm, a mass proportion of graphene of 5 to 20%, and a particle size of 1 μm to 20 μm. The preparation method of the graphene-coated glass powder is as follows: S1: Mix glycogen, graphene oxide and water; S2: Add glass powder to the glycogen and graphene oxide aqueous solution and stir evenly; S3: Add the above substances into a hydrothermal reactor, carry out reduction reaction at a temperature of 200-400°C and a pressure of 123KPa-309KPa for 4h-12h, filter through a 100-400 mesh filter, and bake at 100-200°C for 30-120min to obtain graphene-coated glass powder.

2. A high temperature resistant graphene conductive ink according to claim 1, characterized in that: The glass powder includes the following components in percentage by mass: 30-55% SiO2, 10-35% Al2O3, 5-15% ZnO, 3-5% MgO, and 1-5% SnO2. The melting range of the glass powder is 500-700°C.

3. A high temperature resistant graphene conductive ink according to claim 1, characterized in that: The mass ratio of the graphene-coated glass powder, water-soluble resin, dispersant, leveling agent, defoaming agent and pure water is (200-500): (100-300): (1-10): (20-70): (0.2-3): (100-300).

4. A high temperature resistant graphene conductive ink according to claim 1, characterized in that: The water-soluble resin is one or more of water-based acrylic resin, water-based polyester resin, and water-based polyurethane resin; the dispersant is one or more of carboxylate dispersants, aliphatic amide dispersants, and ester dispersants; the leveling agent is one or more of polyacrylic acid and polyether-modified polysiloxane; and the defoaming agent is selected from one or more of mineral oil and silicone.

5. A method for preparing the high temperature resistant graphene conductive ink according to any one of claims 1 to 4, characterized in that: The following steps are involved: Graphene-coated glass powder is prepared, and the graphene-coated glass powder, a water-soluble resin, a dispersant, a leveling agent, a defoaming agent, and water are mixed and stirred uniformly, and then ground to obtain a water-based, high-temperature-resistant graphene conductive ink.

6. A method for preparing the high temperature resistant graphene conductive ink according to claim 5, characterized in that: The glycogen includes at least one of glucose, fructose, lactose, sucrose, and starch. In step S1, the mass ratio of glycogen, graphene oxide, and water is (5-20): (0.5-4):

100.

7. A method for preparing the high temperature resistant graphene conductive ink according to claim 5, characterized in that: In step S2, the mass ratio of the glycogen and graphene oxide aqueous solution to the glass powder is 100:(10-30).

8. A method for preparing the high temperature resistant graphene conductive ink according to claim 5, characterized in that: The grinding process includes grinding the slurry 3 to 5 times using a three-roll grinder, and controlling the slurry fineness to be below 20 μm.

9. A use of the high temperature resistant graphene conductive ink according to any one of claims 1 to 4 or the high temperature resistant graphene conductive ink prepared by the method according to any one of claims 5 to 8, characterized in that: After coating, the high-temperature resistant graphene conductive ink is sintered and cured in stages. The first stage is sintered at a temperature of 80-150°C for 10-30 minutes; the second stage is sintered at a temperature of 200-350°C for 10-30 minutes; the third stage is sintered at a temperature of 400-650°C for 10-30 minutes; and then cooled to room temperature to complete curing.