A high-performance water-based carbon-based conductive ink, its preparation method and application

Abstract

This invention belongs to the field of printed electronics technology, and relates to a high-performance water-based carbon-based conductive ink, its preparation method, and its application. The raw materials for the high-performance water-based carbon-based conductive ink include: 10-30 parts of conductive filler, 18-30 parts of binder, 32-69 parts of solvent, and 3-8 parts of additives, wherein the conductive filler is composed of graphite and carbon black. Through a simple dispersion and ball milling process, an effective three-dimensional structure of "carbon black-few-carbon black" is constructed, resulting in an ink with low cost, high stability, high conductivity, excellent mechanical flexibility, and environmental friendliness, showing great potential in the field of flexible electronics.

Description

Technical Field

[0001] This invention belongs to the field of printed electronics technology, and more specifically relates to a high-performance water-based carbon-based conductive ink, its preparation method, and its application. Background Technology

[0002] In an era of rapid technological and IoT development, fields such as artificial intelligence, biomedicine, flexible electronics, and new energy are advancing rapidly. The public's demand for lightweight, intelligent, and flexible microelectronic products is constantly increasing, leading to significant achievements in printed electronics technology. Currently, this technology has been applied to the development and use of many electronic products, such as flexible conductive circuits, RFID tags, sensors, wearable devices, and nanorobots. Conductive ink, as a core component of printed electronics technology, can print designed patterns onto various substrates using printing techniques, assembling them into various functional devices, demonstrating immense scientific and commercial value.

[0003] Currently, metal nanomaterial inks are common conductive inks and have been extensively studied due to their high conductivity. However, they suffer from high cost and instability issues, such as metal oxidation and silver electron migration. Therefore, replacing metal materials with stable, inexpensive, chemically inert, and non-toxic carbon materials for large-scale production is of great significance. Although novel carbon nanotubes and graphene have been extensively studied in the ink field due to their excellent mechanical and photoelectric properties, their relatively high price, complex preparation process, and low yield limit their large-scale application in the ink industry. In contrast, traditional graphite and carbon black remain highly attractive to both the scientific and industrial communities due to their practicality and economic advantages.

[0004] In recent years, with the continuous and in-depth implementation of the concept of green development, environmentally friendly materials have received increasing attention from researchers. There is an urgent need to develop a cost-effective, environmentally friendly, high-performance conductive ink that can be mass-produced. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance water-based carbon-based conductive ink, its preparation method, and its application, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions of this invention is to provide a high-performance water-based carbon-based conductive ink, wherein the raw materials, by weight, include:

[0008] The mixture contains 10-30 parts of conductive filler, 18-30 parts of binder, 32-69 parts of solvent, and 3-8 parts of additives.

[0009] Furthermore, the conductive filler is composed of graphite and carbon black in a mass ratio of 10:1 to 3.

[0010] Preferably, the average particle size of the graphite is 1000 to 3000 mesh.

[0011] Preferably, the average particle size of the carbon black is 10–18 nm.

[0012] The beneficial effects of the above-mentioned further and preferred solutions are as follows: the selection of large-size graphite sheets can effectively reduce the contact resistance between graphite sheets, and the addition of small-particle-size carbon black can be more uniformly dispersed on the graphite sheets. While preventing the graphite sheets from agglomerating and stacking, it provides more longitudinal conductive paths, thereby improving the overall conductivity of the material.

[0013] Furthermore, the adhesive is water-based polyurethane.

[0014] Preferably, the waterborne polyurethane includes F0407 type waterborne polyurethane and / or F0410 type waterborne polyurethane, more preferably F0407 type waterborne polyurethane.

[0015] Furthermore, the solvent is deionized water;

[0016] Furthermore, the additives include at least two of the following: aqueous defoamer, aqueous carbon black dispersant, sodium carboxymethyl cellulose, and ethylene glycol.

[0017] Preferably, the aqueous defoamer includes one of BYK028, BYK022 and BYK011, more preferably BYK028.

[0018] Preferably, the aqueous carbon black dispersant includes one of DS-W72H, AKN-2076 and T-859, more preferably T-859.

[0019] The second technical solution of this invention provides a method for preparing a high-performance water-based carbon-based conductive ink, comprising the following steps:

[0020] The high-performance water-based carbon-based conductive ink is obtained by mixing, stirring and dispersing conductive fillers, binders, solvents and additives, followed by ball milling.

[0021] Furthermore, the stirring and dispersion speed is 1000-4000 r / min, and the time is 3-8 h.

[0022] Furthermore, the ball milling speed is 300-800 r / min, and the time is 3-8 h.

[0023] The third technical solution of the present invention provides an application of the above-mentioned high-performance water-based carbon-based conductive ink in the field of flexible electronics.

[0024] Furthermore, the method of application includes: printing circuits or electrodes on the high-performance water-based carbon-based conductive ink on a substrate and then drying it at 25–180°C for 2–12 hours.

[0025] Preferably, the substrate comprises a paper substrate or a polyethylene terephthalate substrate.

[0026] Preferably, the method also includes assembling the dried electrodes into an all-solid-state micro supercapacitor.

[0027] As can be seen from the above technical solution, compared with the existing technology, it has the following beneficial effects:

[0028] This invention constructs a three-dimensional structure of "carbon black-few-carbon black" through a simple dispersion and ball milling process. Using inexpensive graphite and carbon black as conductive fillers, and water and water-soluble components (binders and additives) as the liquid phase, a low-cost, high-stability, high-conductivity, excellent mechanical flexibility, and environmentally friendly ink is prepared.

[0029] The gradient conductive filler used in this invention is composed of graphite and carbon black. Graphite is dispersed at high speed, and the shear force generated by ball milling peels it into thinner few-layer graphite flakes. The addition of carbon black increases the ink viscosity while effectively preventing the agglomeration of the few-layer graphite flakes. A stirring and dispersion process ensures that the ink components are initially uniformly mixed and dispersed. A subsequent ball milling process ensures that the ink components are fully and uniformly mixed and dispersed, with the carbon black adhering more evenly to the few-layer graphite flakes, thereby improving the overall stability and conductivity of the ink material. Subsequently, combined with screen printing technology, the ink can be printed into highly conductive, highly mechanically flexible conductive circuits. These printed conductive circuits can replace some traditional metal wires, enabling circuit assembly. Simultaneously, electrodes with interdigitated structures can also be printed, assembling them into all-solid-state flexible micro supercapacitors for energy storage, demonstrating enormous potential in the field of flexible electronics. Attached Figure Description

[0030] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0031] Figure 1 The surface morphology (a) and (b) observed under a low-power electron microscope after the conductive ink of Example 1 has dried are shown in Figure 1.

[0032] Figure 2 The conductivity change trend of the dried rectangular circuit in Example 2 during 5000 bending-release cycles is shown.

[0033] Figure 3Optical photographs showing that the conductive wire loop assembled in Example 2 can light up a small light bulb after being laid flat (a) and bent 180° (b).

[0034] Figure 4 Optical photograph of the aqueous carbon-based conductive ink prepared in Example 3 after standing for 2 months.

[0035] Figure 5 The conductivity change curve of the water-based carbon-based conductive ink prepared in Example 3 during a 2-month standing period.

[0036] Figure 6 The images show the cyclic voltammetry (a) and constant current charge-discharge diagram (b) of the all-solid-state micro supercapacitor assembled in Example 3.

[0037] Figure 7 The capacitance retention rate of the all-solid-state micro supercapacitor assembled in Example 3 after being repeatedly bent at 120° for 5000 cycles is measured.

[0038] Figure 8 An optical photograph showing how the all-solid-state micro supercapacitor assembled in Example 3 successfully lit up a small light bulb after storing energy.

[0039] Figure 9 The scanned micrographs are for comparative examples 1, 2, 3, 4 and 5, where a) and b) are scanned micrographs for comparative example 1, c) and d) are scanned micrographs for comparative example 2, e) and f) are scanned micrographs for comparative example 3, g) and h) are scanned micrographs for comparative example 4, and i) and j) are scanned micrographs for comparative example 5. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the embodiments of the present invention, the graphite particle size is between 1000 and 3000 mesh, and the carbon black particle size is 15 nm.

[0042] Example 1

[0043] Preparation of water-based carbon-based conductive ink:

[0044] S1. Weigh 22.7g graphite, 2.3g carbon black, 0.3g sodium carboxymethyl cellulose, 2g water-based carbon black dispersant (T-859), 1g water-based defoamer (BYK028), 28.5g water-based polyurethane (F0407 type) and 43.2g deionized water, and add them sequentially to a mixer and disperse at 3500r / min for 4h to obtain a preliminarily mixed ink.

[0045] S2. Place the preliminarily mixed ink into a ball mill jar and ball mill it in an all-around planetary ball mill at a speed of 500 r / min for 3 hours to obtain water-based carbon-based conductive ink.

[0046] Appearance morphology analysis:

[0047] A circular pattern was designed using CAD software, and a 100-mesh screen printing template was created. The pattern was then printed onto a polyethylene terephthalate (PET) substrate using screen printing technology. The printed pattern was placed in an oven and dried at 180°C for 2 hours, allowing the ink to adhere to the PET substrate. The surface morphology was then analyzed using a scanning electron microscope. Figure 1 As shown.

[0048] Figure 1 The images show the surface morphology (a) observed under a low-magnification electron microscope and the surface morphology (b) observed under a high-magnification electron microscope after the conductive ink of Example 1 has dried. Figure 1 (a) It can be seen that the conductive ink prepared in Example 1 has a dense and continuous surface morphology after drying; Figure 1 (b) It can be seen that carbon black acts as a spacer between graphite layers, distributed on the surface of graphite sheets, forming a three-dimensional conductive network structure of carbon black-few-layer graphite-carbon black. This allows for better contact between conductive fillers and the formation of more conductive paths, improving the overall conductivity of the material. Conductivity was tested using an M-3 handheld digital four-probe tester, and the conductivity was 1.40 × 10⁻⁶. 3 S / m exhibits excellent mechanical flexibility.

[0049] Example 2

[0050] Preparation of water-based carbon-based conductive ink:

[0051] S1. Weigh 19.23g graphite, 5.77g carbon black, 0.1g sodium carboxymethyl cellulose, 3g water-based carbon black dispersant (T-859), 1g water-based defoamer (BYK028), 28.69g water-based polyurethane (F0407 type) and 42.21g deionized water, and add them sequentially to a mixer and disperse at 2000r / min for 6h to obtain a preliminarily mixed ink.

[0052] S2. Place the preliminarily mixed ink into a ball mill jar and ball mill it in an all-around planetary ball mill at a speed of 600 r / min for 6 hours to obtain water-based carbon-based conductive ink.

[0053] Mechanical flexibility testing:

[0054] A rectangular circuit pattern was designed using CAD software, and a 200-mesh screen printing template was created. The pattern was then printed onto a polyethylene terephthalate (PET) substrate using screen printing technology. The printed rectangular circuit pattern was placed in an oven and dried at 100°C for 6 hours to allow the ink to adhere to the PET substrate. Mechanical flexibility testing was performed on the dried rectangular circuit pattern using a bend-release method. The conductivity was tested using an M-3 handheld digital four-probe tester, and the conductivity was found to be 1.51 × 10⁻⁶. 3 S / m, the result is as follows Figure 2 As shown.

[0055] Figure 2 The diagram shows the conductivity change trend of the dried rectangular circuit in Example 2 during 5000 bending-releasing cycles. Figure 2 It can be seen that the conductivity of the dried rectangular circuit in Example 2 remained essentially unchanged during 5000 bending-releasing cycles, indicating that the conductive ink of the present invention has excellent stability and mechanical flexibility in circuit printing applications.

[0056] After the circuit is dried, connect the power supply and the light bulb. Assemble the conductive wire circuit and test whether the light bulb can light up under both flat and 180° bending conditions. The results are as follows. Figure 3 As shown.

[0057] Figure 3 Optical photographs showing that the conductive wire loop assembled in Example 2 can light up a small light bulb after being laid flat (a) and bent 180° (b). Figure 3 It can be seen that the circuit printed with the conductive ink of the present invention has excellent mechanical flexibility, which further demonstrates the excellent synergistic effect of the conductive ink formulation design and preparation method of the present invention, showing great potential in the field of flexible electronics.

[0058] Example 3

[0059] Preparation of water-based carbon-based conductive ink:

[0060] S1. Weigh 20.85g graphite, 4.15g carbon black, 0.2g sodium carboxymethyl cellulose, 2g water-based carbon black dispersant (T-859), 1g water-based defoamer (BYK028), 28.37g water-based polyurethane (F0407 type), 4.34g ethylene glycol and 39.08g deionized water, and add them sequentially to a mixer and disperse at 3000r / min for 6h to obtain a preliminarily mixed ink.

[0061] S2. Place the preliminarily mixed ink into a ball mill jar and ball mill it in an all-around planetary ball mill at a speed of 500 r / min for 4 hours to obtain water-based carbon-based conductive ink.

[0062] At room temperature, an anti-settling experiment was conducted on the water-based carbon-based conductive ink prepared in Example 3 using a 25 mL transparent glass bottle. The results are as follows: Figure 4 and Figure 5 As shown.

[0063] Figure 4 Optical photograph of the water-based carbon-based conductive ink prepared in Example 3 after standing for 2 months. Figure 4 It can be seen that the conductive ink prepared by the present invention does not exhibit stratification after standing for 2 months, indicating that the conductive ink prepared by the present invention has excellent stability.

[0064] Figure 5 The conductivity change curve of the water-based carbon-based conductive ink prepared in Example 3 during a two-month standing period. Figure 5 It can be seen that the conductivity of the conductive ink prepared by the present invention does not change significantly during the two-month standing period, which further demonstrates that the conductive ink prepared by the present invention has high stability.

[0065] Interdigitated electrode patterns were designed using CAD software, and a 100-mesh screen printing template was fabricated. The water-based carbon-based conductive ink prepared in Example 3 was used as the printing ink, and the electrodes were printed on a polyethylene terephthalate (PET) substrate using screen printing technology. The printed electrodes were then placed in an oven and dried at 60°C for 8 hours to allow the ink to adhere to the PET substrate. After drying, the electrodes were assembled into an all-solid-state micro supercapacitor, and electrochemical tests were performed. The results are as follows: Figures 6-8 As shown.

[0066] Figure 6 The images show the cyclic voltammogram (a) and galvanostatic charge-discharge diagram (b) of the all-solid-state micro supercapacitor assembled in Example 3. Figure 6 (a) It can be seen that the all-solid-state micro supercapacitor assembled in Example 3 exhibits typical double-layer capacitance characteristics in its cyclic voltammogram within a scan rate range of 5–100 mV / s; Figure 6(b) It can be seen that the all-solid-state micro supercapacitor assembled in Example 3 has an efficiency of 0.05–0.40 mA / cm². 2 The constant current charge-discharge curves within the current density range exhibit an approximately symmetrical triangular shape, further demonstrating the excellent electrochemical capacitance behavior of the assembled all-solid-state micro supercapacitor. Carbon black, adhering to the few-layer graphite sheets and acting as a spacer, effectively prevents graphite aggregation, forming a three-dimensional conductive network structure of "carbon black-few-layer graphite-carbon black" while simultaneously creating more ion channels. This promotes the transport of electrolyte ions in the electrodes, enabling the micro supercapacitor to achieve a capacitance of 0.05 mA / cm². 2 At current density, it has 10.64 mF / cm. 2 Surface capacitance.

[0067] Figure 7 The capacitance retention rate of the all-solid-state micro supercapacitor assembled in Example 3 after 5000 cycles of repeated bending at 120° is given. Figure 7 It can be seen that the all-solid-state micro supercapacitor assembled in Example 3 only degraded by 2.98% after being repeatedly bent at 120° and released 5000 times. This fully demonstrates that the micro supercapacitor prepared by the conductive ink of the present invention has good mechanical flexibility and excellent charge storage capacity under long-term bending cycle. It further shows that the excellent formulation design of the conductive ink of the present invention has great potential in the field of flexible electronics.

[0068] Figure 8 An optical photograph showing how the all-solid-state micro supercapacitor assembled in Example 3 successfully lit up a small light bulb after storing energy.

[0069] Comparative Example 1

[0070] The only difference from Example 1 is that the mass ratio of graphite to carbon black in the conductive filler is 10:0.

[0071] Appearance morphology analysis:

[0072] Figure 9 (a) and (b) are electron microscope images of the conductive ink in Comparative Example 1 after drying. Figure (a) shows that the conductive ink prepared in Comparative Example 1 has a dense and continuous surface morphology after drying. Figure (b) shows that the few-layer graphite sheets form a conductive network by stacking sheets together, but its longitudinal conductivity is poor and it has a large number of voids. The conductivity was measured using an M-3 handheld digital four-probe tester, and the conductivity was 3.12 × 10⁻⁶. 2 S / m.

[0073] Comparative Example 2

[0074] Appearance morphology analysis:

[0075] The only difference from Example 1 is that the graphite in the conductive filler has a particle size of 10,000 mesh.

[0076] Figure 9 (c) and (d) are electron microscope images of the conductive ink in Comparative Example 3 after drying. Compared with Example 1, the film has a denser microstructure under low magnification (image c), and under high magnification, carbon black is observed to fill the material voids and form a conductive network by distributing on the graphite sheet surface (image d). However, the microstructure shows many voids, and the number of contact points between graphite sheets increases (due to the smaller graphite sheet size), resulting in high contact resistance and a decrease in material conductivity. Conductivity was tested using an M-3 handheld digital four-probe tester, and the conductivity was 4.31 × 10⁻⁶. 2 S / m.

[0077] Comparative Example 3

[0078] Appearance morphology analysis:

[0079] The only difference from Example 1 is that the carbon black in the conductive filler has a particle size of 30 nm.

[0080] Figure 9 (e) and (f) are electron microscope images of the conductive ink in Comparative Example 3 after drying. At low magnification, the material exhibits a dense microstructure (e), but due to the increased carbon black particle size, the corresponding amount of carbon black distributed on the graphite sheet decreases (f). Compared to Example 1, the longitudinal conductive path of the material is reduced, resulting in lower conductivity. Conductivity was tested using an M-3 handheld digital four-probe tester, and the conductivity was 4.75 × 10⁻⁶. 2 S / m.

[0081] Comparative Example 4

[0082] Appearance morphology analysis:

[0083] Compared with Example 1, the only difference is that the ball milling step is omitted in the preparation method.

[0084] Figure 9 (g) and (h) are electron micrographs of the conductive ink in Comparative Example 4 after drying. Without the shear force generated by the ball milling process, the graphite flakes show relatively large and thick dimensions, and the material as a whole exhibits a less dense microstructure. The conductivity was measured using an M-3 handheld digital four-probe tester, and the conductivity was 5.37 × 10⁻⁶. 2 S / m.

[0085] Comparative Example 5

[0086] Appearance morphology analysis:

[0087] The only difference from Example 1 is that the mass ratio of conductive filler, binder, solvent and additives is 30:29:37:4.

[0088] Figure 9 Figures (i) and (j) are electron microscope images of the conductive ink after drying in Comparative Example 5. When the specific gravity of the conductive filler increased to 30%, protrusions were observed under low magnification (Figure i). This may be due to oversaturation of the conductive filler, affecting the formation of conductive paths, while the construction of the three-dimensional structure remained largely unaffected (Figure f). Conductivity was tested using an M-3 handheld digital four-probe tester, and the conductivity was 9.83 × 10⁻⁶. 2 S / m.

[0089] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-performance water-based carbon-based conductive ink with a three-dimensional structure of carbon black-few-carbon black flakes, characterized in that, By weight, the raw materials include: Conductive filler 10-30 parts, binder 18-30 parts, solvent 32-69 parts, additives 3-8 parts; The conductive filler is composed of graphite and carbon black; The adhesive is water-based polyurethane; The solvent is deionized water; The additives include at least two of the following: aqueous defoamer, aqueous carbon black dispersant, sodium carboxymethyl cellulose, and ethylene glycol; The mass ratio of graphite to carbon black is 10:1~3; the average particle size of the graphite is 1000~3000 mesh; the average particle size of the carbon black is 10~18 nm; The preparation steps of the high-performance water-based carbon-based conductive ink include: The high-performance water-based carbon-based conductive ink is obtained by mixing, stirring and dispersing conductive fillers, binders, solvents and additives, followed by ball milling. The stirring and dispersing speed is 1000~4000 r / min, and the time is 3~8 h; The ball milling speed is 300~800 r / min, and the time is 3~8 h.

2. The high-performance water-based carbon-based conductive ink according to claim 1, characterized in that, The waterborne polyurethane includes F0407 type waterborne polyurethane and / or F0410 type waterborne polyurethane; the waterborne defoamer includes one of BYK028, BYK022 and BYK011; the waterborne carbon black dispersant includes one of DS-W72H, AKN-2076 and T-859.

3. A method for preparing a high-performance water-based carbon-based conductive ink as described in any one of claims 1 to 2, characterized in that the step... include: The high-performance water-based carbon-based conductive ink is obtained by mixing, stirring and dispersing conductive fillers, binders, solvents and additives, followed by ball milling.

4. The preparation method according to claim 3, characterized in that, The stirring and dispersion speed is 1000~4000 r / min, and the time is 3~8 h.

5. The preparation method according to claim 3, characterized in that, The ball milling speed is 300~800 r / min, and the time is 3~8 h.

6. The application of a high-performance water-based carbon-based conductive ink as described in any one of claims 1 to 2 in the field of flexible electronics.

7. The application according to claim 6, characterized in that, The method of application includes: printing circuits or electrodes on a substrate using the high-performance water-based carbon-based conductive ink, and then drying it at 25~180℃ for 2~12 hours.

8. The application according to claim 7, characterized in that, The substrate includes a paper substrate or a polyethylene terephthalate substrate.

9. The application according to claim 7, characterized in that, It also includes assembling the dried electrodes into an all-solid-state micro supercapacitor.

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