Conductive silver adhesive for carbon film potentiometer and preparation method of conductive silver adhesive

Abstract

The invention belongs to the technical field of electronic conductive adhesives, and relates to a conductive silver adhesive for a carbon film potentiometer and a preparation method of the conductive silver adhesive. The conductive silver adhesive comprises the following raw materials: matrix resin, a curing agent, an MXene material, spherical silver powder, silver nanowires, a coupling agent, a cross-linking agent and an auxiliary agent. The volume resistivity of the conductive silver adhesive is as low as 1.2 * 10 <-4 > omegacm, the contact resistance fluctuation between a carbon film and an electrode is less than or equal to 0.3%, the shear strength can reach 18-22MPa, the perfectness ratio of a conductive layer is still greater than 98% after 100,000 times of sliding wear tests, and the resistivity amplification of the conductive silver adhesive is less than or equal to 4% after 1000 hours of tests in a severe environment of 50 DEG C / 90% relative humidity and a slight vulcanization atmosphere.

Description

Technical Field

[0001] This invention belongs to the field of electronic conductive adhesive technology, and relates to a conductive silver paste for carbon film potentiometers and its preparation method. Background Technology

[0002] Carbon film potentiometers are fundamental components in electronic devices used to regulate voltage and current. Their working principle involves moving a sliding contact across the surface of a carbon film layer, changing the contact area between the carbon film layer and the electrodes, thereby adjusting the resistance value. Conductive silver paste, as a key material connecting the carbon film layer and the metal electrodes in a carbon film potentiometer, directly determines the adjustment accuracy, stability, and lifespan of the potentiometer. However, existing conductive silver pastes used in carbon film potentiometers generally suffer from the following technical drawbacks: weak interfacial adhesion, easy detachment; large fluctuations in contact resistance, resulting in low adjustment accuracy; poor oxidation and wear resistance, leading to a short lifespan. These shortcomings severely restrict the performance improvement of carbon film potentiometers.

[0003] Patent CN115029096A discloses a method for preparing a low-temperature semi-molten MXene-based composite conductive adhesive, comprising: adding a conductive reinforced organic fiber solution to a single layer or 2-5 layers of MXene nanosheets, and ultrasonically dispersing it to obtain a uniform functionalized MXene-based composite material; preparing an ultraviolet-curable organic carrier, and adding a polyurethane thermoplastic elastomer, and stirring evenly to obtain a modified swelling liquid; compounding the functionalized MXene-based composite material, flake silver powder and a trace amount of thermal initiator, adding them to the modified swelling liquid, and stirring evenly to obtain a low-temperature semi-molten MXene-based composite conductive adhesive. However, the component design and process route of this patent are not optimized for the working characteristics of carbon film potentiometers, resulting in significant deficiencies in its core performance and making it completely unsuitable for applications requiring oxidation resistance and high wear resistance. The cross-linking density of the UV-cured organic carrier used is not specifically optimized, leading to insufficient interfacial bonding strength between the conductive silver paste and the carbon film and metal electrodes, making delamination likely. Simultaneously, the low-temperature semi-melt preparation process fails to address the issue of filler dispersion uniformity, and the combined defects of various components exacerbate contact resistance fluctuations, making it difficult to guarantee the potentiometer's adjustment accuracy. The wear resistance and support of ordinary polyurethane thermoplastic elastomers are limited, and the sheet-like silver powder is prone to slippage and detachment under high-frequency reciprocating friction at the sliding contacts, further aggravating the wear of the conductive layer. These problems collectively result in the conductive adhesive lacking an effective protective mechanism, exhibiting poor environmental stability, and allowing moisture and air to easily penetrate and accelerate silver particle oxidation, causing a rapid decline in conductivity and structural stability. This makes it completely unsuitable for the carbon film potentiometer's requirements for strong interfacial bonding, low contact resistance fluctuations, excellent oxidation resistance, wear resistance, and environmental stability.

[0004] Therefore, there is an urgent need to develop a conductive silver paste that is specifically adapted to the working characteristics of carbon film potentiometers and has strong interfacial bonding, low contact resistance fluctuation, excellent oxidation resistance and wear resistance, and environmental stability, so as to break through the existing technical bottlenecks and promote the performance upgrade of carbon film potentiometers. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a conductive silver paste for carbon film potentiometers and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions: A conductive silver paste for carbon film potentiometers, wherein the raw material of the conductive silver paste comprises the following components and their weight percentages: 22-38 parts of matrix resin, 6-14 parts of hardener MXene material 2.5~7.5 parts, 32-58 parts of spherical silver powder 6-14 parts of silver nanowires Crosslinking agent 2.2~4.8 parts, Coupling agent 1.2~2.8 parts, Additives: 1.5-4.5 parts And deionized water; The solid-liquid ratio of the MXene material to deionized water is 1:110~140 (g:mL).

[0007] Furthermore, the matrix resin is a compound of modified bisphenol A type epoxy resin and phenolic resin; the epoxy value of the modified bisphenol A type epoxy resin is 0.4~0.6 eq / 100g.

[0008] Furthermore, the mass ratio of the modified bisphenol A epoxy resin to the phenolic resin is 2 to 4:1; preferably, the mass ratio of the modified bisphenol A epoxy resin to the phenolic resin is 3:1.

[0009] Furthermore, the curing agent is a modified aliphatic amine curing agent; preferably, the curing agent is a polyether amine.

[0010] Furthermore, the MXene material is selected from Ti3C2T. x Ti2CT x V2CT x Nb2CT x One or more of the following; the sheet thickness of the MXene material is 1~50 μm.

[0011] Preferably, the MXene material is Ti3C2T. x .

[0012] Furthermore, the spherical silver powder has a particle size of 1.5~4μm, a sphericity >95%, and a purity ≥99.9%; the silver nanowires have a diameter of 60~90nm, a length of 12~18μm, and a purity ≥99.9%.

[0013] Furthermore, the crosslinking agent is citric acid, preferably food-grade citric acid with a purity ≥99.5%; The coupling agent is a compound of aminosilane coupling agent and epoxysilane coupling agent; Preferably, the mass ratio of aminosilane coupling agent to epoxysilane coupling agent is 1:1.

[0014] Furthermore, the additives include one or more of dispersants, defoamers, and anti-wear agents; wherein the dispersant is BYK-110; the defoamer is organosilicon defoamer BYK-052; and the anti-wear agent is nano-silica with a particle size of 10~100nm.

[0015] Preferably, the mass ratio of the dispersant, defoamer and anti-wear agent is 4:(1~3):(1~3).

[0016] The present invention also provides a method for preparing conductive silver paste for carbon film potentiometers as described in any of the preceding claims, comprising the following steps: S1. MXene pretreatment: MXene material is added to deionized water and ultrasonically dispersed to obtain an MXene suspension; a coupling agent is added to the MXene suspension and stirred evenly to obtain an MXene dispersion; S2. Preparation of resin premix: At room temperature, add the matrix resin, the remaining coupling agent and the dispersant to the stirred tank in sequence, stir evenly to obtain a low viscosity resin premix. S3. Co-dispersion of conductive fillers: Add the MXene dispersion, spherical silver powder and silver nanowires prepared in step S1 to the resin premix prepared in step S2 in sequence, heat to 40~60℃, and stir at 1100~1300r / min for 60~90min. S4. Crosslinking curing and initial product preparation: After step S3 is completed, add the crosslinking agent and stir at 800~1000 r / min for 30~40 min; then add the curing agent, defoamer and anti-wear agent, and continue to stir at 800~1000 r / min for 20~30 min to obtain the initial product of conductive silver paste. S5. Vacuum degassing and finished product preparation: The conductive silver paste obtained in step S4 is vacuum degassed to obtain conductive silver paste for carbon film potentiometers.

[0017] Further, in step S1, the mass of the coupling agent is 0.3~0.7% of the mass of the MXene material; the ultrasonic dispersion is performed at a power of 300~500W for 30~60min; the stirring is performed at 30~40℃ and a speed of 250~350r / min for 20~40min. In step S2, the stirring is performed at a speed of 500~700 r / min for 20~30 min; wherein the ultrasonic power is 200W.

[0018] In step S3, during the stirring process, high-power ultrasonic-assisted dispersion is activated for 10-15 minutes every 25 minutes. In step S5, the vacuum degassing conditions are -0.09MPa vacuum for 15~30min to remove residual bubbles in the mixture.

[0019] After degassing, the final product, MXene / silver-based high-performance conductive silver paste for carbon film potentiometers, is obtained. It can be stored in a sealed container at 25°C in the dark for ≤6 months.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a conductive silver paste for carbon film potentiometers, which is prepared by using MXene material, spherical silver powder and silver nanowires as core conductive fillers and citric acid as crosslinking agent. The conductive silver paste has low contact resistance fluctuation, high oxidation resistance and wear resistance. It is mainly suitable for conductive connection between the electrodes and carbon film layer of carbon film potentiometers and for surface encapsulation of carbon film layer. At the same time, it can effectively solve the technical problems of reduced adjustment accuracy and shortened service life caused by insufficient performance of conductive silver paste in existing carbon film potentiometers during long-term adjustment. It can also be extended to conductive connection of small electronic components (such as carbon film sensors) with similar structure to carbon film potentiometers.

[0021] (2) MXene material, as a novel two-dimensional transition metal carbide, has high conductivity, large specific surface area and abundant surface functional groups (-OH, -F, =O). Its two-dimensional sheet structure can serve as a "conductive bridge" to fill the gaps between silver particles, significantly optimizing the continuity of the conductive path. The surface functional groups can enhance the interfacial bonding force between the conductive silver paste and the carbon film layer. The cross-linking between citric acid and resin and conductive filler forms a multi-linked network, forming a tight "sheet-sphere-wire" three-dimensional conductive network, which can effectively prevent the intrusion of corrosive media such as water and sulfides in the environment, greatly delaying the oxidation of silver powder, thereby improving many shortcomings of traditional conductive silver paste in carbon film potentiometer applications.

[0022] (3) The conductive silver paste used in the carbon film potentiometer of this invention has low contact resistance fluctuation and stable adjustment accuracy: the three-dimensional conductive network of "MXene sheet-spherical silver powder-silver nanowire" is well adapted to the carbon film micro-nano structure, resulting in a volume resistivity of conductive silver paste as low as 1.2×10 -4 The contact resistance fluctuation between the carbon film and the electrode is ≤0.3% (compared to >1.2% for conventional conductive silver paste), ensuring the stability of the potential adjustment accuracy of the carbon film potentiometer during long-term use, with a potential adjustment accuracy error of ≤0.5%.

[0023] (4) The conductive silver paste used in the carbon film potentiometer of the present invention has a strong interface bond and excellent wear resistance: through the synergistic effect of the complex crosslinking agent and citric acid crosslinking, the interface bonding force between the conductive silver paste and the carbon film layer is significantly strengthened, and its shear strength can reach 18~22MPa; at the same time, the anti-wear agent and the spherical silver powder form a synergistic effect, effectively reducing the friction coefficient. After 100,000 sliding wear tests, the integrity rate of the conductive layer is still greater than 98%, which extends the service life of the potentiometer.

[0024] (5) The conductive silver paste used in the carbon film potentiometer of the present invention has high environmental stability and strong long-term reliability: the tight three-dimensional conductive network can effectively block the intrusion of oxygen and corrosive media. In the harsh environment of 50℃ / 90% relative humidity + slight sulfur atmosphere, the resistivity of the conductive silver paste increased by ≤4% after 1000h, ensuring that the carbon film potentiometer can operate stably for a long time under complex working conditions. Attached Figure Description

[0025] Figure 1 This is a comparison chart of the volume resistivity of the conductive silver paste in Examples 1-2 and Comparative Examples 1-2 of the present invention; Figure 2 This is a comparison diagram of the shear strength of the conductive silver paste in Examples 1-2 and Comparative Examples 1-2 of the present invention; Figure 3 This is a photograph of the conductive silver paste sample prepared in Example 1 of the present invention. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0027] Unless otherwise specified, all raw materials used in this invention are commercially available products, such as those described in the following examples and comparative examples: The modified bisphenol A epoxy resin used is model E-54 from Nan Ya Electronic Materials Co., Ltd. The polyetheramine used is Huntsman's D230; The aminosilane coupling agent selected is Dow Chemical's KH-550; The epoxy silane coupling agent selected is Dow Chemical Company's KH-560; MXene material selected is Ti3C2T from XinXi Technology Co., Ltd. x Purity ≥ 99%; Spherical silver powder: particle size 1.5~4μm, sphericity >95%, purity ≥99.9%; Silver nanowires: Silver nanowires with a diameter of 60~90nm and a length of 20~100μm, with a purity of ≥99.9%; The citric acid used is food-grade citric acid with a purity of ≥99.5%; The dispersant used is BYK-110 from BYK GmbH, Germany; The silicone defoamer selected is BYK-052 from BYK GmbH, Germany; The nano-silica anti-wear agent is a product of Wacker Chemie Ltd., with an average particle size of 10~50nm.

[0028] Example 1 A conductive silver paste for carbon film potentiometers is made from the following components and their weight percentages: The composition includes 30 parts of matrix resin, 10 parts of polyetheramine D230, 2 parts of coupling agent, 5 parts of MXene, 45 parts of spherical silver powder, 10 parts of silver nanowires, 3.5 parts of citric acid, 1.2 parts of dispersant BYK-110, 0.3 parts of silicone defoamer BYK-052, 0.3 parts of nano silica, and deionized water. The matrix resin is composed of modified bisphenol A type epoxy resin E-54 and phenolic resin in a mass ratio of 3:1; the coupling agent is composed of aminosilane coupling agent KH-550 and epoxysilane coupling agent KH-560 in a mass ratio of 1:1; and the solid-liquid ratio of MXene to deionized water is 1:125 (g:mL). The conductive silver paste for the carbon film potentiometer provided in this embodiment is prepared using the following specific steps: S1. MXene pretreatment: Add MXene powder to deionized water and ultrasonically disperse at 400W for 45min to obtain MXene suspension; add coupling agent of 0.5% by mass of MXene powder to the MXene suspension and stir at 350r / min at 30℃ for 40min to obtain MXene dispersion. S2. Preparation of resin premix: At room temperature, the matrix resin, the remaining coupling agent and the dispersant are added sequentially to the resin premix obtained in step S2, and stirred at 500 r / min for 30 min to obtain a low viscosity resin premix. S3. Co-dispersion of conductive fillers: Add the MXene dispersion, spherical silver powder and silver nanowires prepared in step S1 to the resin premix prepared in step S2 in sequence, heat to 40°C and stir at 1300 r / min for 60 min; during the stirring process, turn on the ultrasonic-assisted dispersion for 12 min every 25 min, with an ultrasonic power of 200 W.

[0029] S4. Crosslinking Curing and Initial Product Preparation: After step S3 is completed, add the crosslinking agent and stir at 800 r / min for 40 min; then add polyetheramine D230, organosilicon defoamer BYK-052 and nano silica, and continue stirring at 800 r / min for 30 min to obtain the initial product of conductive silver paste.

[0030] S5. Vacuum degassing and finished product preparation: The conductive silver paste obtained in step S4 is degassed at a vacuum of -0.09MPa for 20 minutes to remove residual bubbles in the mixture, thus obtaining conductive silver paste for carbon film potentiometers.

[0031] Figure 3 The conductive silver paste for carbon film potentiometers prepared in this embodiment is shown. Figure 3 As can be seen, the conductive silver paste is silvery-white with a uniform color and excellent rheological properties, making it suitable for electrode coating processes. This is because the silver paste has good dispersibility, which effectively reduces the formation of pores when coated on the electrode surface, thereby improving the interfacial interaction between the silver paste and the electrode.

[0032] Example 2 A conductive silver paste for carbon film potentiometers is made from the following components and their weight percentages: The composition includes 26 parts of matrix resin, 9 parts of polyetheramine D230, 1.8 parts of coupling agent, 4 parts of MXene, 42 parts of spherical silver powder, 9 parts of silver nanowires, 3 parts of citric acid, 0.8 parts of dispersant BYK-110, 0.6 parts of silicone defoamer BYK-052, 0.6 parts of nano silica, and deionized water. The matrix resin is composed of modified bisphenol A type epoxy resin E-54 and phenolic resin in a mass ratio of 3:1; the coupling agent is composed of aminosilane coupling agent KH-550 and epoxysilane coupling agent KH-560 in a mass ratio of 1:1; and the solid-liquid ratio of MXene to deionized water is 1:125 (g:mL). The conductive silver paste for the carbon film potentiometer provided in this embodiment is prepared using the following specific steps: S1. MXene pretreatment: Add MXene powder to deionized water and ultrasonically disperse at 400W for 45min to obtain MXene suspension; add coupling agent of 0.5% by mass of MXene powder to the MXene suspension and stir at 250r / min at 40℃ for 40min to obtain MXene dispersion. S2. Preparation of resin premix: At room temperature, add the matrix resin, the remaining coupling agent and dispersant to the stirred tank in sequence, and stir at 500 r / min for 30 min to obtain a low viscosity resin premix. S3. Co-dispersion of conductive fillers: Add the MXene dispersion, spherical silver powder and silver nanowires prepared in step S1 to the resin premix prepared in step S2 in sequence, heat to 55°C and stir at 1100 r / min for 90 min; during the stirring process, turn on the ultrasonic-assisted dispersion for 12 min every 25 min, with an ultrasonic power of 200 W.

[0033] S4. Crosslinking Curing and Initial Product Preparation: After step S3 is completed, add the crosslinking agent and stir at 1000 r / min for 30 min; then add polyetheramine D230, organosilicon defoamer BYK-052 and nano silica, and continue stirring at 1000 r / min for 20 min to obtain the initial product of conductive silver paste.

[0034] S5. Vacuum degassing and finished product preparation: The initial conductive silver paste is degassed at a vacuum of -0.09MPa for 20 minutes to remove residual bubbles in the mixture, thus obtaining conductive silver paste for carbon film potentiometers.

[0035] Comparative Example 1 A conductive silver paste is prepared in basically the same way as in Example 1, except that MXene material is not added to the raw materials.

[0036] Comparative Example 2 A conductive silver paste is prepared in basically the same way as in Example 1, except that an equal amount of polyetheramine is used to replace citric acid in Example 1 in the raw materials.

[0037] The conductive silver paste prepared in the embodiments and comparative examples of this invention was printed onto a glass substrate using a 300-mesh screen printing process. The printed pattern was a rectangle of 30 mm × 8 mm, and the squeegee gap was set to 50 μm. The formed conductive layer served as the electrode of the carbon film potentiometer. Subsequently, the samples were cured in an air atmosphere at 150°C for 30 min. After cooling to room temperature, the following performance tests were conducted: Volume resistivity: The sample thickness was measured using a Bruker Dektak XT step profiler, and the average value was calculated from the measurements of 5 different regions. The test was conducted using a Keithley 2400 source meter with a linear four-probe probe (probe spacing d=1mm) at an environment of 23℃ and 50% RH. The sample was required to equilibrate in this environment for 24 hours. The instrument operated in constant current mode with a current of I=5mA applied. Five test points were selected, avoiding the sample edge at a distance of ≥2 mm. The volume resistivity was then calculated using the formula.

[0038] Contact resistance fluctuation: Tested according to GB / T 5095.2-1997.

[0039] Shear strength: The tensile shear strength of the conductive silver paste was determined according to the national standard GB7124-86 "Determination of Tensile Shear Strength of Adhesives (Metal to Metal)". The testing equipment used was a CSS-44100 electronic universal testing machine manufactured by Changchun Testing Machine Research Institute, with the tensile rate set to 1 mm / min; 5 samples were selected for each test group, and the average value was taken as the test result.

[0040] Conductive layer integrity rate after 100,000 wear cycles: The test was performed according to ASTM G133-05 (2018) and IEC 60093:2019 standards. The wear test was conducted on a UMT-3 TriboLab testing machine with the following parameters: the friction head used a SUS304 stainless steel ball (6 mm in diameter), the load was 1.0 ± 0.05 N, the stroke was 10 mm, the frequency was 1 Hz, the number of cycles was 100,000, and the resistance value was recorded once every 1,000 cycles. The test environment was 23℃ and 50% RH, and the samples needed to be equilibrated in this environment for 24 hours in advance.

[0041] 1000h environmental test resistivity increase: The test was conducted in accordance with GB / T 2423.4-2013 "Environmental testing of electrical and electronic products - Part 2: Test methods - Test Db: Alternating damp heat (12h+12h cycle)". The resistivity increase of the conductive silver paste was calculated after the test.

[0042] Potential adjustment accuracy error: Tested in accordance with GB / T 13978-2008 "Verification Procedure for DC Potentiometers".

[0043] Table 1. Comparison of performance tests of embodiments and comparative examples of the present invention. Table 1 is a comparison table of performance tests for the embodiments and comparative examples of the present invention. The test data in the table show that the conductive silver paste prepared in Embodiments 1 and 2 of the present invention exhibits significantly better overall performance in the application of carbon film potentiometer electrode coating than Comparative Examples 1 and 2, specifically as follows: The volume resistivity of Examples 1 and 2 is as low as 1.2 × 10⁻⁶. -4 Ω•cm, 1.4×10 -4 Ω•cm, much lower than Comparative Example 1 (7.2×10⁻⁶). -4 Ω•cm) and Comparative Example 2 (3.5×10 -4 Ω•cm), see Figure 1 This indicates that the conductive silver paste of the present invention can construct a highly efficient conductive network, significantly reducing current transmission loss and ensuring low-loss signal transmission for potentiometers. The mechanism lies in the fact that citric acid increases the crosslinking density of the matrix resin and forms hydrogen bonds with the MXene material surface, improving the dispersibility of MXene and the overall mechanical strength of the paste. Simultaneously, MXene acts as a bonding agent in the conductive network, further enhancing conductivity. Furthermore, the contact resistance fluctuations in Examples 1 and 2 are both less than 0.3%, exhibiting more stable resistance output characteristics. This is attributed to the excellent dispersibility and structural stability of the paste, effectively preventing abnormal resistance fluctuations. In addition, the shear strength of Examples 1 and 2 is higher than that of Comparative Examples 1 and 2, fully meeting the application requirements of carbon film potentiometers. This is the result of the synergistic effect of citric acid and MXene; their interaction effectively enhances the shear strength of the adhesive layer.

[0044] In addition, the conductive layer integrity rates after 100,000 wear cycles in Examples 1 and 2 were excellent, reaching 99% and 98% respectively. This is because a strong interaction force was formed between the citric acid crosslinking agent, the matrix resin, and MXene. At the same time, the addition of nano-silica improved the overall wear resistance of the slurry, thereby enhancing the anti-friction ability of the conductive layer. Moreover, the resistivity increase in Examples 1 and 2 after 1000 hours of environmental testing was not significant, much lower than that in Comparative Example 1 (16%) and Comparative Example 2 (28%). This is because the interaction between citric acid and MXene improved the bonding force between materials, hindering the intrusion of water and air, and thus slowing down the oxidation of silver particles.

[0045] Finally, the potential adjustment accuracy error of Examples 1 and 2 is better than that of Comparative Examples 1 and 2. This is due to the good dispersion uniformity and structural stability of the slurry, which ensures the signal accuracy during the potential adjustment process.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A conductive silver paste for carbon film potentiometers, characterized in that, The conductive silver paste raw material includes the following components and their weight percentages: 22-38 parts of matrix resin, 6-14 parts of hardener MXene material 2.5~7.5 parts, 32-58 parts of spherical silver powder 6-14 parts of silver nanowires Crosslinking agent 2.2~4.8 parts, Coupling agent 1.2~2.8 parts, Additives: 1.5-4.5 parts And deionized water; The solid-liquid ratio of the MXene material to deionized water is 1:110~140.

2. The conductive silver paste for carbon film potentiometers according to claim 1, characterized in that, The matrix resin is a compound of modified bisphenol A type epoxy resin and phenolic resin; the epoxy value of the modified bisphenol A type epoxy resin is 0.4~0.6 eq / 100g.

3. The conductive silver paste for carbon film potentiometers according to claim 2, characterized in that, The mass ratio of the modified bisphenol A epoxy resin to the phenolic resin is 2~4:

1.

4. The conductive silver paste for carbon film potentiometers according to claim 1, characterized in that, The curing agent is a modified fatty amine curing agent.

5. The conductive silver paste for carbon film potentiometers according to claim 1, characterized in that, The MXene material is selected from Ti3C2T. x Ti2CT x V2CT x Nb2CT x One or more of the following; the sheet thickness of the MXene material is 1~50 μm.

6. The conductive silver paste for carbon film potentiometers according to claim 1, characterized in that, The spherical silver powder has a particle size of 1.5~4μm, a sphericity >95%, and a purity ≥99.9%; the silver nanowires have a diameter of 60~90nm, a length of 12~18μm, and a purity ≥99.9%.

7. The conductive silver paste for carbon film potentiometers according to claim 1, characterized in that, The crosslinking agent is citric acid; The coupling agent is a compound of aminosilane coupling agent and epoxysilane coupling agent.

8. The conductive silver paste for carbon film potentiometers according to claim 1, characterized in that, The additives include one or more of dispersants, defoamers, and anti-wear agents.

9. A method for preparing conductive silver paste for carbon film potentiometers as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. MXene pretreatment: MXene material is added to deionized water and ultrasonically dispersed to obtain an MXene suspension; a coupling agent is added to the MXene suspension and stirred evenly to obtain an MXene dispersion; S2. Preparation of resin premix: At room temperature, add the matrix resin, the remaining coupling agent and the dispersant to the stirred tank in sequence, stir evenly to obtain a low viscosity resin premix. S3. Co-dispersion of conductive fillers: Add the MXene dispersion, spherical silver powder and silver nanowires prepared in step S1 to the resin premix prepared in step S2 in sequence, heat to 40~60℃, and stir at 1100~1300r / min for 60~90min. S4. Crosslinking curing and initial product preparation: After step S3 is completed, add the crosslinking agent and stir at 800~1000 r / min for 30~40 min; then add the curing agent, defoamer and anti-wear agent, and continue to stir at 800~1000 r / min for 20~30 min to obtain the initial product of conductive silver paste. S5. Vacuum degassing and finished product preparation: The conductive silver paste obtained in step S4 is vacuum degassed to obtain conductive silver paste for carbon film potentiometers.

10. The method for preparing conductive silver paste for carbon film potentiometers according to claim 9, characterized in that, In step S1, the mass of the coupling agent is 0.3~0.7% of the mass of the MXene material; The ultrasonic dispersion is performed at a power of 300-500W for 30-60 minutes; the stirring is performed at 30-40℃ and a speed of 250-350r / min for 20-40 minutes. In step S2, the stirring is performed at a speed of 500~700 r / min for 20~30 min; In step S3, during the stirring process, high-power ultrasonic-assisted dispersion is activated for 10-15 minutes every 25 minutes. In step S5, the vacuum degassing conditions are as follows: degassing at a vacuum of -0.09 MPa for 15 to 30 minutes.

Images