Hollow silver-coated copper particle and preparation method and application thereof

Abstract

The invention discloses hollow silver-coated copper particles and a preparation method and application thereof, and belongs to the technical field of conductive material preparation. Through the unique hollow silver-coated copper particle structure design and the optimized preparation method, the use amount of silver is effectively reduced, and the cost is reduced; meanwhile, the compact silver layer and the surface modification layer can achieve a synergistic effect, so that the oxidation resistance, the conductivity and the dispersity of the hollow silver-coated copper particles are remarkably improved, the hollow silver-coated copper particles have more excellent application performance, the prepared conductive paste is endowed with excellent performance, and the conductive paste is suitable for various curing modes and has good application prospects. The method has a wide application prospect in the fields of photovoltaics, flexible electronics and the like, and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive material preparation, and in particular to a hollow silver-coated copper particle and a preparation method and application thereof. Background Art

[0002] Amidst the rapid development of electronic information, new energy, and other fields, conductive materials, as key foundational materials, have a direct impact on the quality and application of related products. Conductive pastes, as an important form of conductive material, are widely used in photovoltaic cells, flexible electronic devices, and other fields, placing higher demands on their conductivity, stability, and cost.

[0003] Traditional silver-coated copper powders are mostly solid structures, with high silver usage, high costs, and poor slurry rheological properties, making it difficult to meet the needs of high-performance conductive slurries. The solid structure results in high silver usage, significantly increasing production costs. At the same time, the poor rheological properties make it difficult to evenly distribute the slurry during coating, printing, and other processing processes, affecting the conductivity and quality stability of the final product, limiting its application in the field of high-end conductive slurries. For example, Chinese patent publication number CN119480205A discloses a silver skeleton pore structure design that improves conductivity through a porous silver layer, but does not involve a hollow copper core design. The silver layer has a high porosity and insufficient oxidation resistance. Summary of the Invention

[0004] Based on this, in order to solve one of the above problems, the present invention provides a preparation method and application of hollow silver-coated copper particles, and the specific technical solution is as follows:

[0005] A hollow silver-coated copper particle comprises a hollow copper core, a silver layer wrapped around the hollow copper core, and a surface modification layer. The silver layer has a thickness of 10 nm to 50 nm and a coverage of ≥90%. The surface modification layer is one of a benzotriazole passivation layer, a silane coupling agent layer, and a polymer coating layer.

[0006] Furthermore, the thickness of the hollow copper core is 10 nm to 100 nm, and the porosity is 30% to 50%;

[0007] The hollow copper core is in at least one of a tubular, spherical, and ellipsoidal shape.

[0008] In addition, the present invention also provides a method for preparing hollow silver-coated copper particles, the preparation method comprising the following steps:

[0009] The hollow copper core was prepared by hydrothermal method;

[0010] The hollow copper core is activated and then silver-plated to form a silver layer on the surface of the hollow copper core;

[0011] The hollow copper core with a silver layer formed on the surface is added into a surface modification treatment solution and immersed to obtain hollow silver-coated copper particles.

[0012] Furthermore, the hydrothermal method for preparing the hollow copper core is as follows: sodium lauryl sulfate, glucose, sodium hydroxide and copper sulfate are used as raw materials, water is used as solution, and the reaction is carried out in a reactor at 150-170° C. for 20 hours.

[0013] Furthermore, the activation treatment uses at least one of a PdCl2 solution, a SnCl2 solution, and an Au nanoparticle solution.

[0014] Furthermore, the silver plating process uses a silver plating solution, which includes

[0015] AgNO3, a complexing agent and a reducing agent, the pH is controlled at 10-12, the reaction temperature is 30°C-50°C, the time is 20min-60min, and ultrasonic-assisted dispersion is used.

[0016] Furthermore, the complexing agent is at least one of ammonia water and citric acid;

[0017] The reducing agent is at least one of glucose and ascorbic acid.

[0018] Furthermore, the raw materials for preparing the benzotriazole passivation layer include benzotriazole; the raw materials for preparing the silane coupling agent layer include at least one of KH550 silane coupling agent and KH560 silane coupling agent; and the raw materials for preparing the polymer coating layer include polyvinyl pyrrolidone and polyethylene glycol.

[0019] In addition, the present invention also provides an application of hollow silver-coated copper particles, wherein the application of the hollow silver-coated copper particles is used in preparing a conductive paste, and in the preparation of the conductive paste, the mass percentage content of the hollow silver-coated copper particles is 20wt%-80wt%.

[0020] Furthermore, the conductive paste is used in the preparation of photovoltaic back electrodes, flexible circuits and touch devices.

[0021] Compared with the prior art, the present invention also has the following beneficial effects:

[0022] The present invention effectively reduces the amount of silver used and reduces costs through the unique structural design of the hollow silver-coated copper particles and the optimized preparation method. At the same time, the dense silver layer and the surface modification layer can work synergistically to significantly improve the oxidation resistance, conductivity and dispersibility of the hollow silver-coated copper particles, so that the hollow silver-coated copper particles have more excellent application performance and impart excellent performance to the prepared conductive paste. The conductive paste is suitable for various curing methods, has broad application prospects in the fields of photovoltaics, flexible electronics, and is suitable for large-scale production. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] A hollow silver-coated copper particle in one embodiment of the present invention comprises a hollow copper core, a silver layer wrapped around the hollow copper core, and a surface modification layer, wherein the thickness of the silver layer is 10 nm to 50 nm, and the coverage is ≥90%, and the surface modification layer is one of a benzotriazole passivation layer, a silane coupling agent layer, and a polymer coating layer.

[0026] In one embodiment, the thickness of the hollow copper core is 10 nm to 100 nm, and the porosity is 30% to 50%;

[0027] The hollow copper core is in at least one of a tubular, spherical, and ellipsoidal shape.

[0028] In one embodiment, the hollow copper core is obtained by mixing a tubular hollow copper core and a spherical hollow copper core in a mass ratio of (1-3):(1-2).

[0029] In addition, the present invention also provides a method for preparing hollow silver-coated copper particles, the preparation method comprising the following steps:

[0030] The hollow copper core was prepared by hydrothermal method;

[0031] The hollow copper core is activated and then silver-plated to form a silver layer on the surface of the hollow copper core;

[0032] The hollow copper core with a silver layer formed on the surface is added into a surface modification treatment solution and immersed to obtain hollow silver-coated copper particles.

[0033] In one embodiment, the hydrothermal method for preparing the hollow copper core is as follows: sodium lauryl sulfate, glucose, sodium hydroxide and copper sulfate are used as raw materials, water is used as solution, and the reaction is carried out in a reactor at 150-170° C. for 20 hours.

[0034] In one embodiment, the activation treatment uses at least one of a PdCl2 solution, a SnCl2 solution, and an Au nanoparticle solution.

[0035] In one embodiment, the concentrations of the PdCl2 solution, SnCl2 solution, and Au nanoparticle solution are all 0.01M to 0.05M.

[0036] In one embodiment, according to the solid-liquid ratio, during the activation treatment, the ratio of the hollow copper core to the PdCl2 solution or SnCl2 solution or Au nanoparticle solution is 1 g: (10-50) mL.

[0037] In one embodiment, the activation treatment lasts for 5 to 10 minutes, and a reducing activation layer is formed on the surface of the hollow copper core.

[0038] In one embodiment, the silver plating process uses a silver plating solution, which includes AgNO3, a complexing agent and a reducing agent, with a pH controlled at 10 to 12, a reaction temperature of 30°C to 50°C, a reaction time of 20 min to 60 min, and ultrasonic assisted dispersion.

[0039] In one embodiment, the complexing agent is at least one of ammonia and citric acid;

[0040] The reducing agent is at least one of glucose and ascorbic acid.

[0041] In one embodiment, the concentration of AgNO3 in the silver plating solution is 0.05-0.2M.

[0042] In one embodiment, the concentration of the reducing agent is 0.05-0.2M.

[0043] In one embodiment, the silver plating process has a reaction temperature of 30°C to 50°C and a reaction time of 20 minutes to 60 minutes. Super-precision assisted dispersion is used to ensure uniform and compact deposition of the silver layer.

[0044] In one embodiment, the raw materials for preparing the benzotriazole passivation layer include benzotriazole; the raw materials for preparing the silane coupling agent layer include at least one of KH550 silane coupling agent and KH560 silane coupling agent; and the raw materials for preparing the polymer coating layer include polyvinyl pyrrolidone and polyethylene glycol.

[0045] In one embodiment, the surface modification treatment solution is an ethanol solution of benzotriazole, and the concentration of the benzotriazole is 0.05-0.2M.

[0046] In one embodiment, the immersion time is 5 minutes to 15 minutes. Benzotriazole can react chemically with the silver surface to form a passivation film, thereby enhancing the anti-oxidation performance of the particles.

[0047] In addition, the present invention also provides an application of hollow silver-coated copper particles, wherein the application of the hollow silver-coated copper particles is used in preparing a conductive paste, and in the preparation of the conductive paste, the mass percentage content of the hollow silver-coated copper particles is 20wt%-80wt%.

[0048] In one embodiment, the conductive paste further includes an organic vehicle and additives.

[0049] In one embodiment, the organic carrier is terpineol and ethyl cellulose.

[0050] In one embodiment, the additive is at least one of a leveling agent and a defoaming agent.

[0051] In one embodiment, the conductive paste is used in the preparation of photovoltaic back electrodes, flexible circuits, and touch devices.

[0052] The hollow silver-coated copper particles prepared in the above scheme have excellent oxidation resistance, electrical conductivity and dispersibility, and can be used to prepare conductive paste, giving the conductive paste excellent performance.

[0053] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0054] Example 1:

[0055] A method for preparing hollow silver-coated copper particles comprises the following steps:

[0056] 8mmol of sodium dodecyl sulfate, 12mmol of glucose, and 20mmol of sodium hydroxide were dissolved in 80mL of deionized water, and then 25mmol of copper sulfate pentahydrate was added and stirred to form a homogeneous solution. The solution was transferred to a reactor and reacted at 165℃ for 20h. The powder collected by centrifugation was a tubular hollow copper core.

[0057] The hollow copper core was activated with a 0.02 mol / L SnCl solution at a solid-liquid ratio of 1 g:30 mL and immersed for 10 min to form a reducing activation layer on the surface of the hollow copper core.

[0058] A 0.1 mol / L AgNO solution was prepared, citric acid was added for complexation, the pH of the silver plating solution was adjusted to 11, and 0.1 mol / L ascorbic acid was added as a reducing agent; the reaction temperature was 30° C., the reaction time was 30 minutes, and ultrasonic-assisted dispersion was used to improve the deposition uniformity and density of the silver layer, thereby forming a silver layer on the surface of the hollow copper core;

[0059] 3 g of benzotriazole was added to 100 g of 3% ethanol solution, and then the hollow copper core with a silver layer formed on the surface was added, immersed for 1 minute, filtered and washed to obtain hollow silver-coated copper particles.

[0060] The hollow silver-coated copper particles prepared in Example 1 were used in the preparation of a conductive paste. The specific preparation method is as follows:

[0061] The modified hollow silver-coated copper particles, epoxy resin, curing agent, and KH550 were mixed in a mass ratio of 60:35:4:1, and after three-roll grinding (gap of 10 μm), cured at a temperature of 130° C. to obtain a conductive silver paste cured film.

[0062] Example 2:

[0063] A method for preparing hollow silver-coated copper particles comprises the following steps:

[0064] 8 mmol of sodium dodecyl sulfate, 25 mmol of glucose, and 22 mmol of sodium hydroxide were dissolved in 80 mL of deionized water, and then 25 mmol of copper sulfate pentahydrate was added. The mixture was stirred to form a homogeneous solution, which was transferred to a reactor and reacted at 160°C for 20 h. The solution was collected by centrifugation to obtain a spherical hollow copper core.

[0065] The hollow copper core was activated with a 0.015 mol / L SnCl solution according to a solid-liquid ratio of the hollow copper core to the solution of 1 g:30 mL, and immersed for 10 min to form a reducing activation layer on the surface of the hollow copper core;

[0066] A 0.15 mol / L AgNO solution was prepared, citric acid was added for complexation, the pH of the silver plating solution was adjusted to 11, and 0.1 mol / L ascorbic acid was added as a reducing agent. The reaction temperature was 30° C., the reaction time was 30 min, and ultrasound-assisted dispersion was used to improve the deposition uniformity and density of the silver layer, thereby forming a silver layer on the surface of the hollow copper core.

[0067] 3 g of benzotriazole was added to 100 g of 3% ethanol solution, and then the hollow copper core with a silver layer formed on the surface was added, immersed for 1 min, filtered and washed to obtain hollow silver-coated copper particles.

[0068] The hollow silver-coated copper particles prepared in Example 2 were applied to the preparation of a conductive paste. The specific preparation method is as follows:

[0069] The hollow silver-coated copper particles prepared in Example 2, epoxy resin, curing agent, and KH550 were mixed in a mass ratio of 60:35:4:1, and after three-roll grinding (gap of 10 μm), cured at a temperature of 130° C. to obtain a conductive silver paste cured film.

[0070] Example 3:

[0071] 8mmol of sodium dodecyl sulfate, 12mmol of glucose, and 20mmol of sodium hydroxide were dissolved in 80mL of deionized water, and then 25mmol of copper sulfate pentahydrate was added and stirred to form a homogeneous solution. The solution was transferred to a reactor and reacted at 165℃ for 20h. The powder collected by centrifugation was a tubular hollow copper core.

[0072] 8 mmol of sodium dodecyl sulfate, 25 mmol of glucose, and 22 mmol of sodium hydroxide were dissolved in 80 mL of deionized water, and then 25 mmol of copper sulfate pentahydrate was added. The mixture was stirred to form a homogeneous solution, which was transferred to a reactor and reacted at 160°C for 20 h. The solution was collected by centrifugation to obtain a spherical hollow copper core.

[0073] The tubular hollow copper core and the spherical hollow copper core are mixed in a mass ratio of 2:1 to obtain composite hollow copper particles, and mechanical stirring is used in the mixing process to ensure that the two forms of copper powder are evenly dispersed;

[0074] A 0.15 mol / L AgNO solution was prepared, citric acid was added for complexation, the pH of the silver plating solution was adjusted to 11, and 0.1 mol / L ascorbic acid was added as a reducing agent. The reaction temperature was 30° C., the reaction time was 30 min, and ultrasonic-assisted dispersion was used to improve the deposition uniformity and density of the silver layer, thereby forming a silver layer on the surface of the composite hollow copper core.

[0075] 3 g of benzotriazole was added to 100 g of 3% ethanol solution, and then the composite hollow copper core with a silver layer formed on the surface was added, immersed for 1 min, filtered and washed to obtain hollow silver-coated copper particles.

[0076] The hollow silver-coated copper particles prepared in Example 3 were used to prepare a conductive paste. The preparation method of the conductive paste is as follows:

[0077] The modified hollow silver-coated copper powder, epoxy resin, curing agent, KH550 and fumed silica were mixed in a mass ratio of 60:35:3.5:1:0.5, subjected to three-roll grinding (gap 10 μm), and cured at a temperature of 130° C. to obtain a conductive silver paste cured film.

[0078] Comparative Example 1:

[0079] Compared with Example 3, the hollow silver-coated copper particles in Comparative Example 1 do not include a surface modification layer, and the rest are the same as Example 3.

[0080] Comparative Example 2:

[0081] Compared with Example 3, the main raw material for preparing the surface modification layer of the hollow silver-coated copper particles in Comparative Example 2 is replaced by chitosan, and the rest is the same as Example 3.

[0082] Specifically, 3g of chitosan was added to 100g of 3% acetic acid solution, and then the composite hollow copper core with a silver layer formed on the surface was added, immersed for 1min, filtered and washed to obtain hollow silver-coated copper particles.

[0083] Comparative Example 3:

[0084] Compared with Example 3, the hollow silver-coated copper particles in Comparative Example 3 are replaced with solid silver-coated copper particles, and the rest are the same as in Example 3.

[0085] The sheet resistance of the conductive silver paste cured films in Examples 1 to 3 and the conductive silver paste cured films in Comparative Examples 1 to 3 were measured using a four-probe method, as shown in Table 1.

[0086] Table 1: Test results

[0087]

[0088]

[0089] Analysis of the data in Table 1 demonstrates that the hollow silver-coated copper particles prepared in this application exhibit excellent electrical conductivity. The composite hollow silver-coated copper particles of Example 3, in particular, are capable of constructing a three-dimensional conductive network, effectively reducing contact resistance. Therefore, this application aims to optimize the composition and provide a method for preparing hollow silver-coated copper particles. Furthermore, the present application relates to composite hollow silver-coated copper particles obtained by compounding hollow silver-coated copper particles from a slurry, which achieve overall superior electrical conductivity.

[0090] Comparing Comparative Example 1 with Example 3, the hollow copper core particles in Comparative Example 1 did not include a surface modification layer, and otherwise remained the same as Example 3. The results showed that the conductivity in Comparative Example 1 was inferior to that in Example 3. The hollow copper core was exposed, increasing the interface resistance. While the silver layer provided a conductive path, copper oxidation caused increased silver-copper contact resistance.

[0091] Comparative Example 2 is compared with Example 3. In Comparative Example 2, the main raw material for preparing the surface modification layer of the hollow copper core particles is replaced with chitosan. All other preparation methods are the same as in Example 3. Although chitosan can physically isolate oxygen, the chitosan material itself has insulating properties and also increases the interfacial resistance, resulting in a significant decrease in electrical conductivity. This shows that the preferred surface modification layer material of this application can not only effectively solve the problem of anti-oxidation, but also ensure the excellent electrical conductivity of the hollow silver-coated copper particles.

[0092] Comparative Example 3 is similar to Example 3 except that the hollow silver-coated copper particles in Comparative Example 3 are replaced with solid silver-coated copper particles. Although solid silver-coated copper particles have certain electrical conductivity, their preparation cost is relatively high. Furthermore, when used in the preparation of conductive pastes, their solidity leads to accelerated sedimentation rates and agglomeration, which affects their application.

[0093] In summary, this application ensures the application performance of the prepared hollow silver-coated copper particles at a lower production cost by optimizing the ingredients, and can be quantified and have high application value.

[0094] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A hollow silver-coated copper particle, characterized in that: The hollow silver-coated copper particles include a hollow copper core, a silver layer wrapped around the hollow copper core, and a surface modification layer. The thickness of the silver layer is 10nm to 50nm, and the coverage is ≥90%. The surface modification layer is one of a benzotriazole passivation layer, a silane coupling agent layer, and a polymer coating layer.

2. The hollow silver-coated copper particles according to claim 1, characterized in that The thickness of the hollow copper core is 10nm to 100nm, and the porosity is 30% to 50%; The hollow copper core is in at least one of a tubular, spherical, and ellipsoidal shape.

3. A method for preparing hollow silver-coated copper particles, characterized in that: The preparation method is used to prepare the hollow silver-coated copper particles according to claim 1 or 2, and the preparation method comprises the following steps: The hollow copper core was prepared by hydrothermal method; The hollow copper core is activated and then silver-plated to form a silver layer on the surface of the hollow copper core; The hollow copper core with a silver layer formed on the surface is added into a surface modification treatment solution and immersed to obtain hollow silver-coated copper particles.

4. The preparation method according to claim 3, characterized in that The hydrothermal method for preparing the hollow copper core comprises the following steps: using sodium lauryl sulfate, glucose, sodium hydroxide and copper sulfate as raw materials, using water as solution, and reacting in a reactor at 150-170° C. for 20 hours.

5. The preparation method according to claim 3, characterized in that The activation treatment uses at least one of a PdCl2 solution, a SnCl2 solution, and an Au nanoparticle solution.

6. The preparation method according to claim 3, characterized in that The silver plating process uses a silver plating solution, which includes AgNO3, a complexing agent and a reducing agent, with a pH controlled at 10-12, a reaction temperature of 30°C-50°C, a reaction time of 20min-60min, and ultrasonic-assisted dispersion.

7. The preparation method according to claim 6, characterized in that The complexing agent is at least one of ammonia water and citric acid; The reducing agent is at least one of glucose and ascorbic acid.

8. The preparation method according to claim 3, characterized in that The raw materials for preparing the benzotriazole passivation layer include benzotriazole; the raw materials for preparing the silane coupling agent layer include at least one of KH550 silane coupling agent and KH560 silane coupling agent; and the raw materials for preparing the polymer coating layer include polyvinyl pyrrolidone and polyethylene glycol.

9. An application of hollow silver-coated copper particles, characterized in that: The application is the application of the hollow silver-coated copper particles according to claim 1 in preparing a conductive paste, and in the preparation of the conductive paste, the mass percentage content of the hollow silver-coated copper particles is 20wt%-80wt%.

10. The use according to claim 9, characterized in that The conductive paste is used in the preparation of photovoltaic back electrodes, flexible circuits and touch devices.

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