Composite conductive ink containing mica functional filler and preparation method thereof

Abstract

The invention relates to a composite conductive ink containing a mica functional filler and a preparation method thereof, and relates to the field of conductive inks, the composite conductive ink comprises the following components by weight: 15-25 parts of organic resin, 20-35 parts of a solvent, 15-20 parts of a first conductive filler, 10-15 parts of a second conductive filler, 0.8-2 parts of a coupling agent, and 3-5 parts of an auxiliary agent; the first conductive filler is modified mica powder, and the modified mica powder is obtained by modifying mica powder through carbon dioxide supercritical fluid carrying imidazolium ionic liquid containing long straight chain alkyl. Compared with the prior art, the special modified mica powder and the special modified flaky copper powder are mainly introduced and are matched for use and have a synergistic effect, so that the resistance of the conductive ink is reduced, the bending resistance of a conductive ink coating is remarkably improved, and the use requirements in the field of flexible electronics are met.

Description

Technical Field

[0001] This invention relates to the field of conductive inks, and more particularly to a composite conductive ink containing mica functional filler and its preparation method. Background Technology

[0002] With the rapid development of electronic information technology, flexible electronic devices, due to their unique bendable and foldable characteristics, have shown enormous application potential in many fields such as wearable devices, electronic skin, and flexible displays. Conductive ink, as a key material in flexible electronics manufacturing, directly determines the quality and reliability of flexible electronic products. Conductive ink must possess good conductivity to ensure stable transmission of electronic signals; simultaneously, during the frequent bending and twisting operations of flexible electronic devices, the conductive ink coating must have excellent bending resistance to prevent cracking, peeling, and other problems, thereby ensuring the normal operation of the device. Therefore, developing conductive inks that combine low resistance and high bending resistance has become a critical problem that urgently needs to be solved in the field of flexible electronics.

[0003] Currently, most conductive inks on the market use traditional conductive fillers, such as ordinary metal powders (copper powder, silver powder, etc.) and carbon-based materials (graphite, carbon nanotubes, etc.). While these conductive fillers can impart conductivity to the ink to some extent, they have significant limitations. Taking ordinary copper powder as an example, its dispersion in ink is poor, and it is prone to agglomeration, resulting in discontinuous conductive pathways and high resistance, which cannot meet the low resistance requirements of high-precision electronic devices. In addition, the bending resistance of coatings formed by these conductive inks is generally poor, failing to meet the long-term use requirements of flexible electronic devices. Summary of the Invention

[0004] To address the above problems, this invention provides a composite conductive ink containing mica functional filler and its preparation method.

[0005] In a first aspect, the present invention provides a composite conductive ink containing mica functional filler, comprising the following components in parts by weight: The mixture comprises 15-25 parts organic resin, 20-35 parts solvent, 15-20 parts first conductive filler, 10-15 parts second conductive filler, 0.8-2 parts coupling agent, and 3-5 parts additives. The first conductive filler is modified mica powder, which is obtained by modifying mica powder by carrying imidazole ionic liquid containing long straight-chain alkyl groups with supercritical carbon dioxide fluid. The second conductive filler includes modified flake copper powder, which is obtained by modifying flake copper powder with cage-type polysilsesquioxane.

[0006] Furthermore, by weight, it includes the following components: The composition includes 20 parts of matrix resin, 30 parts of solvent, 18 parts of first conductive filler, 12 parts of second conductive filler, 1.5 parts of coupling agent, and 4.5 parts of additives.

[0007] Furthermore, the preparation of the modified mica powder includes the following process: The mica powder is placed in a sealed device containing the imidazole ionic liquid, with the mica powder and the imidazole ionic liquid not in direct contact. The volume of the imidazole ionic liquid added accounts for 3-7% of the volume of the sealed device. Air is removed and CO2 is introduced. The system temperature is adjusted to 65-70°C and the pressure is 12-15 MPa. The modification treatment is carried out under this supercritical state for 2-4 minutes. The pressure is then released to obtain the modified mica powder.

[0008] Furthermore, the particle size of the mica powder is 5-20 nanometers; The imidazole ionic liquid containing a long straight-chain alkyl group includes at least one of 1-heptyl-3-methylimidazolium bromide, 1-octyl-2,3-dimethylimidazolium bromide, and 1-decyl-3-methylimidazolium bromide.

[0009] Furthermore, the preparation of the modified flake copper powder includes the following process: The flake copper powder and the cage-type polysilsesquioxane were added to an ethanol aqueous solution with a pH of 4.2-4.8, and ultrasonically heated and stirred for 45-60 minutes at an ultrasonic power of 300-400W and a temperature of 50-60°C. The mixture was then filtered and dried to obtain the modified flake copper powder.

[0010] Furthermore, the weight ratio of the cage-shaped polysilsesquioxane, the flake copper powder, and the ethanol aqueous solution is (0.7~1.0):(10~15):(20~25), the ethanol aqueous solution is composed of ethanol and water in a volume ratio of (1~2):(2~3), and the flake copper powder has a diameter of 3~8 micrometers.

[0011] Furthermore, the additives include leveling agents, dispersants, and antioxidants in a weight ratio of (1~2):(1~2):(0.5~1).

[0012] Further, the organic resin includes at least one of acrylic resin and epoxy resin, the solvent includes at least one of diethylene glycol butyl ether acetate and diethylene glycol dibenzoate, the coupling agent includes a silane coupling agent, the silane coupling agent includes γ-aminopropyltriethoxysilane, the leveling agent includes an organosilicon leveling agent, the organosilicon leveling agent includes BYK-306, the dispersant includes at least one of BYK-111 and BYK-190, the antioxidant includes a phenolic antioxidant, the phenolic antioxidant includes butylated hydroxytoluene.

[0013] Secondly, based on the same inventive concept, this invention provides a method for preparing a composite conductive ink containing mica functional filler, the preparation method comprising the following steps: The organic resin, solvent, and additives are stirred and mixed to obtain the first mixture; The first conductive filler and the second conductive filler are stirred and mixed to obtain a second mixture; The second mixture and coupling agent are added to the first mixture and stirred and mixed, and then ground to obtain the composite conductive ink.

[0014] Furthermore, the working conditions for grinding include: a grinding speed of 150~200 rpm and a grinding time of 20~30 min.

[0015] The technical solutions provided in the embodiments of the present invention have at least the following advantages compared with the prior art: This invention provides a composite conductive ink containing mica functional filler and its preparation method. Compared with the prior art, this invention mainly introduces specific modified mica powder and specific modified flake copper powder. The two are used in combination, and their synergistic effect not only reduces the resistance of the conductive ink but also significantly improves the bending resistance of the conductive ink coating, thereby meeting the application requirements in the field of flexible electronics. Specifically: 1) This invention utilizes supercritical carbon dioxide fluid, which possesses a high diffusion coefficient and low surface tension, and carries imidazole ionic liquids containing long-chain alkyl groups to modify mica powder. This reduces surface energy and improves compatibility with organic resins. Simultaneously, the imidazole cations in the ionic liquid provide additional conductive pathways, synergizing with the sheet-like conductive properties of mica itself. This reduces surface energy and improves compatibility with organic resins; the imidazole cations in the ionic liquid provide additional conductive pathways, synergizing with the sheet-like conductive properties of mica itself, forming a layered conductive network in the ink, reducing contact resistance between fillers. Furthermore, its excellent heat resistance and dimensional stability enhance the coating's resistance to bending fatigue.

[0016] 2) This invention utilizes cage-like polysilsesquioxane (POSS) to chemically bond or physically coat the surface of flake copper powder, forming a nanoscale protective layer. The siloxane skeleton of POSS can inhibit the oxidation of copper powder, and its cage-like structure can buffer external stress, improving the oxidation resistance and mechanical strength of copper powder; at the same time, the organic side chains of POSS can form chemical bonds with organic resins, enhancing interfacial adhesion.

[0017] Based on this, the present invention utilizes the layered structure of modified mica powder and the sheet-like structure of modified flake copper powder to form a complementary composite conductive mode of "surface-to-surface" contact and "point-to-surface" contact, thereby constructing a highly efficient three-dimensional conductive network. At the same time, through interface strengthening and dispersion optimization, it achieves excellent performance of low resistance and high bending resistance, meeting the high requirements of the flexible electronics field for conductive inks. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0019] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. Furthermore, unless otherwise specified or detailed, the steps and parameters involved in this invention can be performed according to publicly available preparation processes or directly using existing equipment; these will not be elaborated upon further in this document.

[0020] The technical solution provided by this invention is as follows: In a first aspect, the present invention provides a composite conductive ink containing mica functional filler, comprising the following components in parts by weight: The mixture comprises 15-25 parts organic resin, 20-35 parts solvent, 15-20 parts first conductive filler, 10-15 parts second conductive filler, 0.8-2 parts coupling agent, and 3-5 parts additives. The first conductive filler is modified mica powder, which is obtained by modifying mica powder by carrying imidazole ionic liquid containing long straight-chain alkyl groups with supercritical carbon dioxide fluid. The second conductive filler includes modified flake copper powder, which is obtained by modifying flake copper powder with cage-type polysilsesquioxane.

[0021] Compared to existing technologies, this invention primarily introduces specifically modified mica powder and specifically modified flake copper powder. The two are used in combination, achieving a synergistic effect that not only reduces the resistance of the conductive ink but also significantly improves the bending resistance of the conductive ink coating, thereby meeting the application requirements in the field of flexible electronics. Specifically: 1) This invention utilizes supercritical carbon dioxide fluid, which possesses a high diffusion coefficient and low surface tension, and carries imidazole ionic liquids containing long-chain alkyl groups to modify mica powder. This reduces surface energy and improves compatibility with organic resins. Simultaneously, the imidazole cations in the ionic liquid provide additional conductive pathways, synergizing with the sheet-like conductive properties of mica itself. This reduces surface energy and improves compatibility with organic resins; the imidazole cations in the ionic liquid provide additional conductive pathways, synergizing with the sheet-like conductive properties of mica itself, forming a layered conductive network in the ink, reducing contact resistance between fillers. Furthermore, its excellent heat resistance and dimensional stability enhance the coating's resistance to bending fatigue.

[0022] 2) This invention utilizes cage-like polysilsesquioxanes (POSS) (e.g., commercially available cage-like polysilsesquioxanes such as Q-0153526, specifically CA0298-OctaMaleamic Acid POSS) to chemically bond or physically coat the surface of flake-like copper powder, forming a nanoscale protective layer. The siloxane skeleton of POSS can inhibit the oxidation of copper powder, and its cage-like structure can buffer external stress, improving the oxidation resistance and mechanical strength of copper powder; at the same time, the organic side chains of POSS can form chemical bonds with organic resins, enhancing interfacial adhesion.

[0023] Based on this, the present invention utilizes the layered structure of modified mica powder and the sheet-like structure of modified flake copper powder to form a complementary composite conductive mode of "surface-to-surface" contact and "point-to-surface" contact, thereby constructing a highly efficient three-dimensional conductive network. At the same time, through interface strengthening and dispersion optimization, it achieves excellent performance of low resistance and high bending resistance, meeting the high requirements of the flexible electronics field for conductive inks.

[0024] As one embodiment of the present invention, the components are included in parts by weight as follows: The composition includes 20 parts of matrix resin, 30 parts of solvent, 18 parts of first conductive filler, 12 parts of second conductive filler, 1.5 parts of coupling agent, and 4.5 parts of additives.

[0025] As one embodiment of the present invention, the preparation of the modified mica powder includes the following process: The mica powder is placed in a sealed device containing the imidazole ionic liquid, with the mica powder and the imidazole ionic liquid not in direct contact. The volume of the imidazole ionic liquid added accounts for 3-7% of the volume of the sealed device (for example, 5% of the volume of the sealed device). Air is removed and CO2 is introduced. The system temperature is adjusted to 65-70°C (for example, 68°C) and the pressure is 12-15 MPa (for example, 14 MPa). The modification treatment is carried out under this supercritical state for 2-4 minutes. The pressure is then released to obtain the modified mica powder.

[0026] In one embodiment of the present invention, the particle size of the mica powder is 5-20 nanometers (e.g., 10 nanometers, 15 nanometers, or 18 nanometers). The imidazole ionic liquid containing a long straight-chain alkyl group includes at least one of 1-heptyl-3-methylimidazolium bromide, 1-octyl-2,3-dimethylimidazolium bromide, and 1-decyl-3-methylimidazolium bromide.

[0027] As one embodiment of the present invention, the preparation of the modified flake copper powder includes the following process: The flake copper powder and the cage-like polysilsesquioxane are added to an ethanol aqueous solution with a pH of 4.2-4.8 (e.g., adjusted with acetic acid or dilute hydrochloric acid). The mixture is ultrasonically heated and stirred for 45-60 minutes at an ultrasonic power of 300-400W (e.g., 320W, 350W, or 380W) and a temperature of 50-60°C (e.g., 55°C). The mixture is then filtered and dried to obtain the modified flake copper powder.

[0028] In one embodiment of the present invention, the weight ratio of the cage-shaped polysilsesquioxane, the flake copper powder, and the ethanol aqueous solution is (0.7~1.0):(10~15):(20~25), for example, 0.8:12:23; the ethanol aqueous solution is composed of ethanol and water in a volume ratio of (1~2):(2~3), and the flake copper powder has a diameter of 3~8 micrometers.

[0029] In one embodiment of the present invention, the additives include leveling agents, dispersants and antioxidants in a weight ratio of (1~2):(1~2):(0.5~1).

[0030] In one embodiment of the present invention, the organic resin includes at least one of acrylic resin (such as B-728) and epoxy resin (such as EPOXY METHACRYLATE 97-053), the solvent includes at least one of diethylene glycol butyl ether acetate and diethylene glycol dibenzoate, the coupling agent includes a silane coupling agent, the silane coupling agent includes γ-aminopropyltriethoxysilane, the leveling agent includes an organosilicon leveling agent, the organosilicon leveling agent includes BYK-306, the dispersant includes at least one of BYK-111 and BYK-190, the antioxidant includes a phenolic antioxidant, the phenolic antioxidant includes butylated hydroxytoluene.

[0031] Secondly, based on the same inventive concept, this invention provides a method for preparing a composite conductive ink containing mica functional filler, the preparation method comprising the following steps: The organic resin, solvent, and additives are stirred and mixed to obtain the first mixture; The first conductive filler and the second conductive filler are stirred and mixed to obtain a second mixture; The second mixture and coupling agent are added to the first mixture and stirred and mixed, and then ground to obtain the composite conductive ink.

[0032] As one embodiment of the present invention, the working conditions parameters for grinding include: grinding speed of 150~200 rpm and grinding time of 20~30 min.

[0033] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0034] Example 1 This example provides a composite conductive ink containing mica functional filler, which, by weight, comprises the following components: The matrix resin (specifically composed of acrylic resin and epoxy resin in a 1:1 mass ratio) consists of 20 parts, the solvent consists of diethylene glycol butyl ether acetate and diethylene glycol dibenzoate in a 2:1 volume ratio, the first conductive filler consists of 18 parts, the second conductive filler consists of 12 parts, the coupling agent (specifically γ-aminopropyltriethoxysilane) consists of 1.5 parts, and the additives consist of 4.5 parts. The first conductive filler is modified mica powder, which is obtained by modifying mica powder with a particle size of 15 nanometers by carrying imidazole ionic liquid containing long straight-chain alkyl groups (specifically 1-octyl-2,3-dimethylimidazolium bromide) with supercritical carbon dioxide fluid. The preparation method specifically includes: placing the mica powder in a closed device containing the imidazole ionic liquid, wherein the mica powder and the imidazole ionic liquid do not directly contact each other, the volume of the imidazole ionic liquid added accounts for 5% of the volume of the closed device, removing air and introducing CO2, adjusting the system temperature to 68°C and the pressure to 14 MPa and maintaining this supercritical state for modification treatment for 3 minutes, depressurizing, and obtaining the modified mica powder. The second conductive filler is modified flake copper powder, which is obtained by modifying flake copper powder with a particle size of 5 micrometers with cage-type polysilsesquioxane (specific product model Q-0153526); the preparation method includes: adding the flake copper powder and the cage-type polysilsesquioxane to an ethanol aqueous solution with a pH of 4.5, ultrasonically heating and stirring for 50 min at an ultrasonic power of 350W and a temperature of 55℃, filtering and drying to obtain the modified flake copper powder; The additives consist of a leveling agent (specifically BYK-306), a dispersant (specifically BYK-111), and an antioxidant (specifically butylated hydroxytoluene) in a weight ratio of 1:2:0.8.

[0035] The preparation method of the above-mentioned composite conductive ink includes the following steps: The organic resin, solvent, and additives are stirred and mixed to obtain the first mixture; The first conductive filler and the second conductive filler are stirred and mixed to obtain a second mixture; The second mixture and coupling agent are added to the first mixture and stirred and mixed, and then ground at a speed of 180 rpm for 25 minutes to obtain the composite conductive ink.

[0036] Example 2 This example provides a composite conductive ink containing mica functional filler, which, by weight, comprises the following components: The matrix resin (specifically composed of acrylic resin and epoxy resin in a mass ratio of 1:1) is 15 parts, the solvent is 20 parts (specifically composed of diethylene glycol butyl ether acetate and diethylene glycol dibenzoate in a volume ratio of 2:1), the first conductive filler is 15 parts, the second conductive filler is 10 parts, the coupling agent (specifically γ-aminopropyltriethoxysilane) is 0.8 parts, and the additives are 3 parts. The first conductive filler is modified mica powder, which is obtained by modifying mica powder with a particle size of 15 nanometers by carrying imidazole ionic liquid containing long straight-chain alkyl groups (specifically 1-octyl-2,3-dimethylimidazolium bromide) with supercritical carbon dioxide fluid. The preparation method specifically includes: placing the mica powder in a closed device containing the imidazole ionic liquid, wherein the mica powder and the imidazole ionic liquid do not directly contact each other, the volume of the imidazole ionic liquid added accounts for 5% of the volume of the closed device, removing air and introducing CO2, adjusting the system temperature to 70°C and the pressure to 15 MPa and maintaining this supercritical state for modification treatment for 2 minutes, depressurizing, and obtaining the modified mica powder. The second conductive filler is modified flake copper powder, which is obtained by modifying flake copper powder with a particle size of 5 micrometers with cage-type polysilsesquioxane (specific product model Q-0153526); the preparation method includes: adding the flake copper powder and the cage-type polysilsesquioxane to an ethanol aqueous solution with a pH of 4.5, ultrasonically heating and stirring for 50 min at an ultrasonic power of 350W and a temperature of 55℃, filtering and drying to obtain the modified flake copper powder; The additives consist of a leveling agent (specifically BYK-306), a dispersant (specifically BYK-111), and an antioxidant (specifically butylated hydroxytoluene) in a weight ratio of 1:2:0.8.

[0037] The preparation method of the above-mentioned composite conductive ink includes the following steps: The organic resin, solvent, and additives are stirred and mixed to obtain the first mixture; The first conductive filler and the second conductive filler are stirred and mixed to obtain a second mixture; The second mixture and coupling agent are added to the first mixture and stirred and mixed, and then ground at a speed of 150 rpm for 20 minutes to obtain the composite conductive ink.

[0038] Example 3 This example provides a composite conductive ink containing mica functional filler, which, by weight, comprises the following components: The matrix resin (specifically composed of acrylic resin and epoxy resin in a mass ratio of 1:1) consists of 25 parts, solvent (specifically composed of diethylene glycol butyl ether acetate and diethylene glycol dibenzoate in a volume ratio of 2:1), first conductive filler 20 parts, second conductive filler 15 parts, coupling agent (specifically γ-aminopropyltriethoxysilane) 1.5 parts, and additives 5 parts. The first conductive filler is modified mica powder, which is obtained by modifying mica powder with a particle size of 15 nanometers by supercritical carbon dioxide carrying an imidazole ionic liquid containing long straight-chain alkyl groups (specifically 1-octyl-2,3-dimethylimidazolium bromide). The preparation method specifically includes: placing the mica powder in a closed device containing the imidazole ionic liquid, wherein the mica powder and the imidazole ionic liquid are not in direct contact, the volume of the imidazole ionic liquid added accounts for 5% of the volume of the closed device, removing air and introducing CO2, adjusting the system temperature to 60°C and the pressure to 12 MPa and maintaining this supercritical state for modification treatment for 4 minutes, depressurizing, and obtaining the modified mica powder. The second conductive filler is modified flake copper powder, which is obtained by modifying flake copper powder with a particle size of 5 micrometers with cage-type polysilsesquioxane (specific product model Q-0153526); the preparation method includes: adding the flake copper powder and the cage-type polysilsesquioxane to an ethanol aqueous solution with a pH of 4.5, ultrasonically heating and stirring for 50 min at an ultrasonic power of 350W and a temperature of 55℃, filtering and drying to obtain the modified flake copper powder; The additives consist of a leveling agent (specifically BYK-306), a dispersant (specifically BYK-111), and an antioxidant (specifically butylated hydroxytoluene) in a weight ratio of 1:2:0.8.

[0039] The preparation method of the above-mentioned composite conductive ink includes the following steps: The organic resin, solvent, and additives are stirred and mixed to obtain the first mixture; The first conductive filler and the second conductive filler are stirred and mixed to obtain a second mixture; The second mixture and coupling agent are added to the first mixture and stirred and mixed, and then ground at a speed of 200 rpm for 30 minutes to obtain the composite conductive ink.

[0040] Comparative Example 1 This example provides a composite conductive ink containing mica functional filler and its preparation method, which differs from Example 1 only in that: (1) The mica powder was not modified; that is, the mica powder raw material in Example 1 was used. (2) The flake copper powder was not modified; that is, the flake copper powder raw material in Example 1 was used.

[0041] Comparative Example 2 This example provides a composite conductive ink containing mica functional filler and its preparation method, which differs from Example 1 only in that: (1) The mica powder was not modified; that is, the mica powder raw material in Example 1 was used.

[0042] Comparative Example 3 This example provides a composite conductive ink containing mica functional filler and its preparation method, which differs from Example 1 only in that: (1) The flake copper powder was not modified; that is, the flake copper powder raw material in Example 1 was used.

[0043] Test case In this example, the conductive inks obtained in the above embodiments and comparative examples were screen-printed (300 mesh) onto a PI substrate and cured at 180°C for 30 minutes to form a rectangular coating of 10mm × 50mm × 50μm. Then, conductivity and bending resistance were tested. Conductivity was tested using a four-probe resistivity meter (probe spacing 1mm), and the average volume resistivity (Ω·cm) was calculated. Bending resistance was tested using a cylindrical shaft bending tester (shaft diameter 1mm) with 180° reciprocating bends at a bending speed of 30 times / min. After every 100 bends, the four-probe method was used to test the coating resistivity change. The number of bends at which cracks appeared or a sudden increase in resistivity (100% increase from the initial value) was recorded, and this number was used as an evaluation index of the coating's mechanical toughness.

[0044] The test results are shown in Table 1.

[0045] Table 1 As shown in Table 1, compared with Comparative Examples 1-3, the conductive ink provided by the present invention has better conductivity and bending resistance. The specific modified mica powder and the specific modified flake copper powder exhibit a positive synergistic effect, and the resulting conductive ink can meet the application requirements in the field of flexible electronics.

[0046] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0047] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement 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 present 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 claimed herein.

Claims

1. A composite conductive ink containing mica functional filler, characterized in that, By weight, it comprises the following components: The mixture comprises 15-25 parts organic resin, 20-35 parts solvent, 15-20 parts first conductive filler, 10-15 parts second conductive filler, 0.8-2 parts coupling agent, and 3-5 parts additives. The first conductive filler is modified mica powder, which is obtained by modifying mica powder by carrying imidazole ionic liquid containing long straight-chain alkyl groups with supercritical carbon dioxide fluid. The second conductive filler includes modified flake copper powder, which is obtained by modifying flake copper powder with cage-type polysilsesquioxane.

2. The composite conductive ink containing mica functional filler according to claim 1, characterized in that, By weight, it comprises the following components: The composition includes 20 parts of matrix resin, 30 parts of solvent, 18 parts of first conductive filler, 12 parts of second conductive filler, 1.5 parts of coupling agent, and 4.5 parts of additives.

3. The composite conductive ink containing mica functional filler according to claim 1, characterized in that, The preparation of the modified mica powder includes the following process: The mica powder is placed in a sealed device containing the imidazole ionic liquid, with the mica powder and the imidazole ionic liquid not in direct contact. The volume of the imidazole ionic liquid added accounts for 3-7% of the volume of the sealed device. Air is removed and CO2 is introduced. The system temperature is adjusted to 65-70°C and the pressure is 12-15 MPa. The modification treatment is carried out under this supercritical state for 2-4 minutes. The pressure is then released to obtain the modified mica powder.

4. The composite conductive ink containing mica functional filler according to claim 3, characterized in that, The particle size of the mica powder is 5-20 nanometers; The imidazole ionic liquid containing a long straight-chain alkyl group includes at least one of 1-heptyl-3-methylimidazolium bromide, 1-octyl-2,3-dimethylimidazolium bromide, and 1-decyl-3-methylimidazolium bromide.

5. The composite conductive ink containing mica functional filler according to claim 1, characterized in that, The preparation of the modified flake copper powder includes the following process: The flake copper powder and the cage-type polysilsesquioxane were added to an ethanol aqueous solution with a pH of 4.2-4.8, and ultrasonically heated and stirred for 45-60 minutes at an ultrasonic power of 300-400W and a temperature of 50-60°C. The mixture was then filtered and dried to obtain the modified flake copper powder.

6. The composite conductive ink containing mica functional filler according to claim 5, characterized in that, The weight ratio of the cage-shaped polysilsesquioxane, the flake copper powder, and the ethanol aqueous solution is (0.7~1.0):(10~15):(20~25), the ethanol aqueous solution is composed of ethanol and water in a volume ratio of (1~2):(2~3), and the flake copper powder has a diameter of 3~8 micrometers.

7. The composite conductive ink containing mica functional filler according to claim 1, characterized in that, The additives include leveling agents, dispersants, and antioxidants in a weight ratio of (1~2):(1~2):(0.5~1).

8. The composite conductive ink containing mica functional filler according to claim 7, characterized in that, The organic resin includes at least one of acrylic resin and epoxy resin; the solvent includes at least one of diethylene glycol butyl ether acetate and diethylene glycol dibenzoate; the coupling agent includes a silane coupling agent, specifically γ-aminopropyltriethoxysilane; the leveling agent includes an organosilicon leveling agent, specifically BYK-306; the dispersant includes at least one of BYK-111 and BYK-190; and the antioxidant includes a phenolic antioxidant, specifically butylated hydroxytoluene.

9. A method for preparing a composite conductive ink containing mica functional filler according to any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: The organic resin, solvent, and additives are stirred and mixed to obtain the first mixture; The first conductive filler and the second conductive filler are stirred and mixed to obtain a second mixture; The second mixture and coupling agent are added to the first mixture and stirred and mixed, and then ground to obtain the composite conductive ink.

10. The method for preparing the composite conductive ink containing mica functional filler according to claim 9, characterized in that, The working conditions for grinding include: grinding speed of 150~200 rpm and grinding time of 20~30 min.

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