Graphene-modified copper-based flexible electronic ink material and preparation method thereof

Abstract

The application discloses a graphene modified copper-based flexible electronic ink material and a preparation method thereof, and belongs to the field of nanomaterials. The method is characterized in that: graphene is modified on nano copper powder, the graphene modified copper powder is mixed with terpineol, centrifuged to prepare graphene-spherical copper powder particles, and then the graphene modified copper-based flexible electronic ink material is prepared by mixing the graphene-spherical copper powder particles with an adhesive, a solvent and a diluent through a specific dispersion technique. The graphene modified copper-based flexible electronic printing ink prepared by the method has greatly improved conductive and heat conductive performance, and even exceeds ordinary silver-based electronic printing ink. The graphene modified copper-based flexible electronic printing ink greatly reduces pollution generated during preparation of traditional PCB and FPC circuit films, and suppresses oxidation of a conductor surface in a circuit. The graphene modified copper-based flexible electronic printing ink saves a large amount of metal conductive materials and other preparation materials, and is suitable for large-scale production due to simple production equipment, short production period and simple process.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials, specifically relating to a graphene-modified copper-based flexible electronic ink material and its preparation method. Background Technology

[0002] Once a high-performance chip is manufactured, it cannot be used independently in any device. It must be mounted on a circuit board (PCB) along with other components and installed in a device (computer, mobile phone, instrument, etc.) to be used. Traditional PCB manufacturing involves 20 to 30 steps, from material preparation, drilling, copper plating, lamination, exposure, development, etching, and finally surface treatment and packaging. This process has the following drawbacks: 1. Complex process: Too many steps affect product yield and performance stability; complex equipment and heavy asset investment; complex material management; 2. Acid in the etching process is difficult to recover and wastes a large amount of metal material, causing serious environmental pollution; 3. Difficult to form multi-layer circuit stacking; 4. The etching process accelerates the oxidation of metals exposed to air in the circuit, thus necessitating a surface treatment step in the process, increasing costs; 5. The etching process wastes a large amount of circuit metal material (approximately 80%), and the tin stripping process also wastes material.

[0003] Meanwhile, with the continuous development of electronic products, flexible printed circuit boards (FPCs) have been increasingly used in mobile phones, computers, televisions, medical devices, and other applications in recent years. This has amplified the shortcomings of traditional circuit board manufacturing processes.

[0004] In recent years, with the development of nanomaterials, electronic ink printing technology is gradually being introduced into PCB manufacturing processes. Electronic ink is a conductive ink that conducts current through conductive materials dispersed within an ink carrier. It mainly consists of conductive materials, binders (organic carriers), additives, and solvents. Currently, conductive inks primarily use micro / nano gold powder, silver powder, copper powder, and conductive carbon black as conductive fillers. Gold and silver powder conductive inks have good chemical stability and excellent conductivity, but their cost is too high. Silver powder conductive inks also suffer from poor resistance to solder erosion, silver ion migration, and sulfidation. Copper powder conductive inks are easily oxidized, resulting in unstable conductivity; therefore, 45%–65% silver powder is still required, leading to high costs. Defect-free graphene is currently the material with the best electrical and thermal conductivity in the world. Graphene conductive ink can be flexible and its formulation ratio can be adjusted to allow it to cure and conduct electricity at room temperature, which is not possible with conventional conductive silver ink. It can be widely used in flexible printed circuit board (FPC) printing. However, it is precisely because of these superior properties that the super strong van der Waals forces between its molecules make it difficult to disperse and thus difficult to apply. Summary of the Invention

[0005] This invention addresses the shortcomings of traditional PCB manufacturing techniques and the deficiencies of current electronic inks by providing a graphene-modified copper-based flexible electronic ink material and its preparation method. This material exhibits higher conductivity than currently used silver-based electronic printing inks and is also cost-effective.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A method for preparing a graphene-modified copper-based flexible electronic ink material, such as... Figure 1 As shown, the specific steps include:

[0008] S1: Dissolve carboxymethyl cellulose or polyvinylpyrrolidone in N-methylpyrrolidone at a ratio of 1 mg / 1 ml, then add nano copper powder to the above mixture and stir until homogeneous. Add graphene and stir mechanically to obtain mixture 1.

[0009] S2: Take 10% of the weight of terpineol in mixture 1 and dissolve it in anhydrous ethanol at room temperature to prepare a solution containing 15% terpineol by weight, thus obtaining mixture 2.

[0010] S3: Place the three-necked flask in an oil bath, then add mixture 1 into the flask. Attach an electric stirrer, thermometer, and constant-pressure dropping funnel. Heat the oil bath to 75–85°C and maintain the temperature. While stirring, add mixture 2 dropwise through the constant-pressure dropping funnel. After the addition is complete, continue stirring for 5–8 hours. Pour the reaction mixture from the flask and centrifuge at 1500–3000 rpm in a high-speed centrifuge to obtain graphene-spherical copper powder particles.

[0011] S4: Graphene-spherical copper powder particles, binder, solvent, and diluent are mixed in a three-roll mixer or high-shear pulper at a speed of 3000-8000 rpm for 5-10 hours to obtain graphene-modified copper-based flexible electronic ink material.

[0012] Preferably, carboxymethyl cellulose or polyvinylpyrrolidone, nano copper powder, and graphene are fed in a weight ratio of (0.05-0.5):(1-5):(1-3).

[0013] Preferably, the stirring time in step S1 is 4 to 24 hours, and the stirring speed is 100 to 800 rpm.

[0014] Preferably, the graphene-spherical copper powder particles, binder, solvent, and diluent are fed in a weight ratio of (10-50):(1-10):(10-40):(10-20).

[0015] Preferably, the adhesive in step S4 includes wood glue, wood glue, cyanoacrylate, contact cement, latex, mortar, glue, methylcellulose, resorcinol resin, starch, methyl ethyl ketone, dichloromethane acrylic acid, ethylene-vinyl alcohol, phenolic resin, polyamide, polyester, polyethylene, polypropylene, polysulfide, polyurethane, polyvinyl acetate, aliphatic, polyvinyl alcohol, polyvinyl chloride, polyvinyl chloride emulsion, silicone, styrene acrylate, epichlorohydrin, epoxide, or any combination thereof, and the adhesive diluent includes butyl acetate, varnish diluent, acetone, naphtha, mineral oil, xylene, or any combination thereof.

[0016] Preferably, the solvent in step S4 has the ability to dissolve resin, disperse fillers and dissolve diluents in the ink, improve the printability of the ink, and adjust viscosity and drying speed. It includes, but is not limited to, at least one of water, aliphatic hydrocarbon solvents (such as heptane), alcohol solvents (such as ethanol), ketone solvents (such as acetone), aromatic hydrocarbon solvents (such as toluene), ester solvents (such as ethyl acetate), alcohol ether solvents (such as ethylene glycol methyl ether), animal and vegetable oils, and mineral oils.

[0017] Preferably, the diluent in step S4 is a commonly used additive in ink preparation processes, which can improve the conductivity, stability, surface properties of printed products, and printability of inks. It includes, but is not limited to, at least one of dispersants, stabilizers, antioxidants, lubricants, defoamers, coupling agents, leveling agents, ultraviolet absorbers, film-forming aids, crosslinking agents, and metal powders.

[0018] This invention utilizes defect-free graphene to modify copper-based electronic printing inks with flexible graphene, which is effective not only for PCB printing and fabrication, overcoming all the shortcomings of traditional PCB manufacturing processes, but also for FPC printing and fabrication. The defect-free graphene has a purity of over 99%, with a single-layer graphene proportion of 95%, and possesses a large specific surface area (700m²). 2 / g, with a single particle plane diameter reaching tens of micrometers), and good electrical conductivity (conductivity measured by the four-probe method ≥1.315×10 6 S / m, i.e., resistivity ≤ 7.6 × 10 -7 Graphene possesses excellent properties such as high thermal conductivity (≥4700 W / m·K), antistatic and electromagnetic shielding properties, and corrosion resistance. Its ultra-large diameter / thickness ratio allows for easy and uniform composite formation with other materials, such as polymers, creating a favorable interface. This enhances the mechanical strength of the cured cross-linked conductive ink, making it particularly suitable for printing inks. This invention utilizes graphene with a sheet-like structure as the conductive filler in conductive inks. The high contact probability between the sheets and the low percolation threshold allow for easy formation of a conductive network within the matrix at a low filling ratio (0.5–2% by weight). This reduces the amount of conductive filler required in the conductive ink, thus lowering costs.

[0019] The copper-based graphene flexible electronic printing ink material prepared by the method of this invention has the following beneficial effects:

[0020] 1. The conductivity is significantly improved, even surpassing that of ordinary silver-based electronic printing inks;

[0021] 2. The manufacturing process of PCB circuit boards and FPC circuit films is simplified, saving a large amount of materials used in the preparation of PCB circuit boards and FPC circuit films, especially metallic conductive materials;

[0022] 3. Significantly reduces pollution generated during the preparation of traditional PCB circuit boards and FPC circuit films, and can inhibit the oxidation of conductor surfaces in PCB circuit boards or FPC circuit film circuits;

[0023] 4. The production equipment is simple, the production cycle is short, and the process is simple, making it suitable for large-scale production. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the preparation process of the copper-based graphene flexible electronic printing ink of the present invention. Detailed Implementation

[0025] Example 1:

[0026] S1: Dissolve carboxymethyl cellulose in N-methylpyrrolidone at a ratio of 1 mg / 1 ml, then add nano copper powder to the above mixture and mix well, then add graphene. The solid components are placed in a mixer at a weight ratio of CMC: nano copper powder: graphene = 0.1:2:1 and mechanically stirred at 200 rpm for 6 hours to obtain mixture 1.

[0027] S2: Dissolve 10% by weight of the solids in the mixture in step 1) in anhydrous ethanol at room temperature to prepare a solution containing 15% by weight of terpineol, thus obtaining mixture 2.

[0028] S3: Place the three-necked flask in an oil bath, then add mixture 1 into the flask, attach an electric stirrer, a thermometer, and a constant-pressure dropping funnel, heat the oil bath to 80°C and maintain the temperature, then add mixture 2 dropwise through the constant-pressure dropping funnel while stirring. The reaction ends after 4 hours. Pour the reaction mixture out of the flask and centrifuge at 1500 rpm in a high-speed centrifuge to obtain graphene-spherical copper powder particles.

[0029] S4: Ink composition formulation and dosage by weight ratio: The graphene-spherical copper powder particles obtained in step 3), binder (CMC), solvent (NMP), and diluent (butyl acetate) are mixed in a ratio of 10:2:10:10 in a three-roll mixer or high-shear pulping machine at 3000 rpm for 6 hours to obtain copper-based graphene flexible electronic printing ink.

[0030] Example 2:

[0031] S1: Dissolve carboxymethyl cellulose (CMC) in NMP at a ratio of 1 mg / 1 ml, then add nano copper powder to the above mixture and mix well, then add graphene. The composition is CMC: copper powder: graphene = 0.5: 5: 1 by weight. Put the mixture into a mixer and mechanically stir at 800 rpm for 20 hours to obtain mixture 1.

[0032] S2: Dissolve 10% by weight of the solids in the mixture in step 1) in anhydrous ethanol at room temperature to prepare a solution containing 15% by weight of terpineol, thus obtaining mixture 2.

[0033] S3: Place the three-necked flask in an oil bath, then add mixture 1 into the flask, attach an electric stirrer, a thermometer, and a constant-pressure dropping funnel, heat the oil bath to 80°C and maintain the temperature, then add mixture 2 dropwise through the constant-pressure dropping funnel while stirring. The process ends after 8 hours. Pour the system out of the flask and centrifuge at 3000 rpm in a high-speed centrifuge to obtain graphene-spherical copper powder particles.

[0034] S4: Ink composition formulation and dosage by weight ratio: The graphene-spherical copper powder particles, binder, solvent and diluent obtained in step 3) are mixed in a ratio of 50:10:40:20 in a three-roll mixer or high-shear pulping machine at 8000 rpm for 10 hours to obtain copper-based graphene flexible electronic printing ink.

[0035] Example 3:

[0036] S1: Dissolve carboxymethyl cellulose (CMC) in NMP at a ratio of 1 mg / 1 ml, then add nano copper powder to the above mixture and mix well, then add graphene. The composition is CMC: copper powder: graphene = 0.25: 2.5: 1 by weight. Put the mixture into a mixer and mechanically stir at 500 rpm for 12 hours to obtain mixture 1.

[0037] S2: Dissolve 10% by weight of the solids in the mixture in step 1) in anhydrous ethanol at room temperature to prepare a solution containing 15% by weight of terpineol, thus obtaining mixture 2.

[0038] S3: Place the three-necked flask in an oil bath, then add mixture 1 into the flask, attach an electric stirrer, a thermometer, and a constant-pressure dropping funnel, heat the oil bath to 80°C and maintain the temperature, then add mixture 2 dropwise through the constant-pressure dropping funnel while stirring. The addition is completed after 6 hours; pour the system out of the flask and centrifuge at 2000 rpm in a high-speed centrifuge to obtain graphene-spherical copper powder particles;

[0039] S4: Ink composition formulation and dosage by weight ratio: The graphene-spherical copper powder particles, binder, solvent and diluent obtained in step 3) are mixed in a ratio of 30:5:25:15 in a three-roll mixer or high-shear pulping machine at 5000 rpm for 8 hours to obtain copper-based graphene flexible electronic printing ink.

[0040] Example 4:

[0041] S1: Dissolve carboxymethyl cellulose (CMC) in NMP at a ratio of 1 mg / 1 ml, then add nano copper powder to the above mixture and mix well, then add graphene. The composition is CMC: copper powder: graphene = 0.25: 2.5: 2 by weight. Put the mixture into a mixer and mechanically stir at 500 rpm for 12 hours to obtain mixture 1.

[0042] S2: Dissolve 10% by weight of the solids in the mixture in step 1) in anhydrous ethanol at room temperature to prepare a solution containing 15% by weight of terpineol, thus obtaining mixture 2.

[0043] S3: Place the three-necked flask in an oil bath, then add mixture 1 into the flask, attach an electric stirrer, a thermometer, and a constant-pressure dropping funnel, heat the oil bath to 80°C and maintain the temperature, then add mixture 2 dropwise through the constant-pressure dropping funnel while stirring. The addition is completed after 6 hours; pour the system out of the flask and centrifuge at 2000 rpm in a high-speed centrifuge to obtain graphene-spherical copper powder particles;

[0044] S4: Ink composition formulation and dosage by weight ratio: The graphene-spherical copper powder particles, binder, solvent and diluent obtained in step 3) are mixed in a ratio of 30:5:25:15 in a three-roll mixer or high-shear pulping machine at 5000 rpm for 8 hours to obtain copper-based graphene flexible electronic printing ink.

[0045] Example 5:

[0046] S1: Dissolve carboxymethyl cellulose (CMC) in NMP at a ratio of 1 mg / 1 ml, then add nano copper powder to the above mixture and mix well, then add graphene. The composition is CMC: copper powder: graphene = 0.25: 2.5: 3 by weight. Put the mixture into a mixer and mechanically stir at 500 rpm for 12 hours to obtain mixture 1.

[0047] S2: Dissolve 10% by weight of the solids in the mixture in step 1) in anhydrous ethanol at room temperature to prepare a solution containing 15% by weight of terpineol, thus obtaining mixture 2.

[0048] S3: Place the three-necked flask in an oil bath, then add mixture 1 into the flask, attach an electric stirrer, a thermometer, and a constant-pressure dropping funnel, heat the oil bath to 80°C and maintain the temperature, then add mixture 2 dropwise through the constant-pressure dropping funnel while stirring. The addition is completed after 6 hours; pour the system out of the flask and centrifuge at 2000 rpm in a high-speed centrifuge to obtain graphene-spherical copper powder particles;

[0049] S4: Ink composition formulation and dosage by weight ratio: The graphene-spherical copper powder particles, binder, solvent and diluent obtained in step 3) are mixed in a ratio of 30:5:25:15 in a three-roll mixer or high-shear pulping machine at 5000 rpm for 8 hours to obtain copper-based graphene flexible electronic printing ink.

[0050] Table 1 lists the relevant properties of the copper-based graphene flexible electronic printing inks prepared in Examples 1-5. As can be seen from the table, the present invention has the following characteristics: the graphene content has the greatest impact on the conductivity of the ink; the more graphene added, the better the conductivity of the ink; when the graphene content by weight reaches 1.5%, its conductivity exceeds that of silver-based electronic printing ink; other components and process parameters have little impact on the technical parameters of the printing ink.

[0051] Table 1 Performance of Copper-Based Graphene Electronic Printing Ink Samples

[0052]

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. The present invention refers to GB / T36650-2018.

Claims

1. A method for preparing a graphene-modified copper-based flexible electronic ink material, characterized in that, Includes the following steps: S1: Dissolve carboxymethyl cellulose or polyvinylpyrrolidone in N-methylpyrrolidone at a ratio of 1 mg / 1 ml, then add nano copper powder to the mixture and stir until homogeneous. Add graphene and stir mechanically to obtain mixture 1. S2: Take 10% of the weight of terpineol from the solids in mixture 1 of step S1 and dissolve it in anhydrous ethanol at room temperature to prepare a terpineol-containing solution, wherein the mass percentage of terpineol is 15%, to obtain mixture 2. S3: Place the three-necked flask in an oil bath, then add mixture 1 into the flask. Attach an electric stirrer, thermometer, and constant-pressure dropping funnel. Heat the oil bath to 75–85°C and maintain the temperature. While stirring, add mixture 2 dropwise through the constant-pressure dropping funnel. After the addition is complete, continue stirring for 5–8 hours. Pour the reacted mixture from the flask and centrifuge at 1500–3000 rpm to obtain graphene-spherical copper powder particles. S4: Graphene-spherical copper powder particles, binder, solvent, and diluent are mixed in a three-roll mixer or high-shear pulper at a speed of 3000-8000 rpm for 5-10 hours to obtain graphene-modified copper-based flexible electronic ink material.

2. The method for preparing a graphene-modified copper-based flexible electronic ink material according to claim 1, characterized in that, In step S1, carboxymethyl cellulose or polyvinylpyrrolidone, nano copper powder, and graphene are fed in a weight ratio of (0.05-0.5):(1-5):(1-3).

3. The method for preparing a graphene-modified copper-based flexible electronic ink material according to claim 1, characterized in that, The stirring time in step S1 is 4 to 24 hours, and the stirring speed is 100 to 800 rpm.

4. The method for preparing a graphene-modified copper-based flexible electronic ink material according to claim 1, characterized in that, In step S4, the graphene-spherical copper powder particles, binder, solvent, and diluent are added in a weight ratio of (10-50):(1-10):(10-40):(10-20).

5. The method for preparing a graphene-modified copper-based flexible electronic ink material according to claim 1, characterized in that, The adhesive is one or more of the following: wood glue, cyanoacrylate, methylcellulose, resorcinol resin, starch, phenolic resin, polyamide, polyester, polyethylene, polypropylene, polysulfide, polyurethane, polyvinyl alcohol, polyvinyl chloride, and styrene acrylate, and any combination thereof with the adhesive diluent, including butyl acetate, acetone, naphtha, mineral oil, and xylene.

6. The method for preparing a graphene-modified copper-based flexible electronic ink material according to claim 1, characterized in that, The solvent includes at least one of water, aliphatic hydrocarbon solvents, alcohol solvents, ketone solvents, aromatic hydrocarbon solvents, ester solvents, alcohol ether solvents, animal and vegetable oils, and mineral oils.

7. A graphene-modified copper-based flexible electronic ink material, characterized in that, The material is prepared by any one of the preparation methods described in claims 1-6.

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