Porous spherical silver powder and preparation method thereof

Abstract

The present application relates to a porous spherical silver powder and a preparation method thereof. The preparation method comprises: preparing a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution; adding the silver nitrate solution and the reducing agent solution to the neutralizer solution, and then adding the first modifier solution for a first modification treatment to obtain a first modified silver powder suspension; separating the first modified silver powder from the first modified silver powder suspension; adding the first modified silver powder to a dispersing solvent, and then adding the second modifier solution for a second modification treatment to obtain a second modified silver powder suspension; separating the second modified silver powder from the second modified silver powder suspension, wherein the second modified silver powder is a porous spherical silver powder, thereby preparing a porous spherical silver powder with good comprehensive electrical properties, which has good application prospects in conductive slurries, conductive coatings and other fields.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic conductive material preparation, and in particular to a porous spherical silver powder and a preparation method thereof. Background Art

[0002] With the development of the times, clean energy has gradually attracted people's attention. The country has promoted a new energy security strategy, which has rapidly promoted the development of wind power and photovoltaic related industries. The photovoltaic power generation field is the top priority. Among them, silver powder, as the most important and largest component of conductive paste, is naturally the focus of development. Silver powder is also the main raw material that determines the comprehensive electrical properties of conductive paste.

[0003] In order to meet the needs of industry development, the requirements for silver powder in the conductive paste used in photovoltaic power generation are becoming higher and higher, requiring the control of silver powder morphology, particle size, particle size distribution, tap density, specific surface area, burn loss, etc. Moreover, with the development of the industry, the requirements for silver powder are not only limited to the characterization data of the silver powder itself, but also require it to have better comprehensive electrical properties, higher filling rate, better printability, etc.

[0004] However, the silver powder in the prior art has the problem of poor comprehensive electrical properties. Summary of the invention

[0005] The purpose of the present application is to provide a porous spherical silver powder and a preparation method thereof, so as to prepare a porous spherical silver powder with good comprehensive electrical properties, so that it can have good application prospects in multiple fields such as conductive pastes and conductive coatings.

[0006] The present application provides a method for preparing porous spherical silver powder, and the method for preparing porous spherical silver powder comprises:

[0007] preparing a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizing agent solution;

[0008] After adding the silver nitrate solution and the reducing agent solution to the neutralizing agent solution, the first modifier solution is added to perform a first modification treatment to obtain a first modified silver powder suspension;

[0009] Separating the primary modified silver powder from the primary modified silver powder suspension;

[0010] After adding the first modified silver powder to the dispersion solvent, a second modifier solution is added to perform a second modification treatment to obtain a second modified silver powder suspension;

[0011] The secondary modified silver powder is separated from the secondary modified silver powder suspension, and the secondary modified silver powder is porous spherical silver powder.

[0012] Among them, the first modifier solution is a modifier solution with a first concentration and a first volume, and the second modifier solution is a modifier solution with a second concentration and a second volume, and the second concentration is greater than or equal to the first concentration, and the second volume is greater than or equal to the first volume.

[0013] Wherein, the modifier solution is an anhydrous ethanol solution of octanoic acid.

[0014] Among them, the first concentration is 5.08~6.5g / L.

[0015] The ratio of the mass of silver nitrate in the silver nitrate solution to the mass of the modifier in the first modifier solution is 196.85 to 153.8.

[0016] The method of separating the first modified silver powder from the first modified silver powder suspension comprises: performing solid-liquid separation after settling the first modified silver powder suspension, and washing, drying and sieving the separated solid to obtain the first modified silver powder.

[0017] Among them, after adding the first modified silver powder to the dispersion solvent, a second modifier solution is added for a second modification treatment to obtain a second modified silver powder suspension, including: stirring the dispersion solvent, and during the stirring process, after adding the first modified silver powder to the dispersion solvent, a second modifier solution is added for a second modification treatment to obtain a second modified silver powder suspension.

[0018] The method of separating the secondary modified silver powder from the secondary modified silver powder suspension comprises: centrifuging and drying the secondary modified silver powder suspension, and drying and grinding the solid obtained by centrifugation to obtain the secondary modified silver powder.

[0019] Among them, after adding silver nitrate solution and reducing agent solution to the neutralizer solution, adding the first modifier solution for the first modification treatment to obtain a first modified silver powder suspension, including: stirring the neutralizer solution, and during the stirring process, after adding silver nitrate solution and reducing agent solution to the neutralizer solution, adding the first modifier solution within a preset addition time for the first modification treatment to obtain a first modified silver powder suspension, wherein the preset addition time is less than or equal to 1 minute.

[0020] The embodiment of the present application also provides a porous spherical silver powder, which is prepared by any of the above-mentioned methods for preparing porous spherical silver powder.

[0021] The porous spherical silver powder and the preparation method thereof provided by the present application are prepared by preparing a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution, and adding the silver nitrate solution and the reducing agent solution to the neutralizer solution, and then adding the first modifier solution to perform a first modification treatment to obtain a first modified silver powder suspension, and then separating the first modified silver powder from the first modified silver powder suspension, and adding the first modified silver powder to a dispersing solvent, and then adding the second modifier solution to perform a second modification treatment to obtain a second modified silver powder suspension, and then Secondary modified silver powder is separated from the secondary modified silver powder suspension. The secondary modified silver powder is a porous spherical silver powder, so that porous spherical silver powder with advantages such as lower burn-in loss, higher tap density, better particle size distribution, and better printability can be prepared. Silver powders with different particle sizes, different specific surface areas, and different conductive properties can be obtained according to different application scenarios. The porous structure of the silver powder particles has higher activity, which ensures that the porous spherical silver powder has better comprehensive electrical properties and can have good application prospects in conductive slurries, conductive coatings and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0023] Figure 1 It is a schematic flow chart of a method for preparing porous quasi-spherical silver powder provided in an embodiment of the present application;

[0024] Figure 2 is a scanning electron microscope image of the porous spherical silver powder prepared by the method for preparing the porous spherical silver powder provided in Example 1 of the present application;

[0025] Figure 3 This is a scanning electron microscope image of the porous spherical silver powder prepared by the method for preparing the porous spherical silver powder provided in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0026] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0027] In the following description of the present application, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0028] In the following description of the present application, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described here can be implemented in an order other than that illustrated or described here.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0030] The following is a detailed description with reference to specific embodiments. It should be noted that the serial numbers of the following embodiments are not intended to limit the preferred order of the embodiments.

[0031] See also Figure 1 , Figure 1 : is a schematic diagram of a process for preparing a porous spherical silver powder provided in an embodiment of the present application. The specific process of the method for preparing the porous spherical silver powder can be as follows:

[0032] Step S11. Prepare a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizing agent solution.

[0033] In this embodiment, the first modifier solution may be a modifier solution having a first concentration and a first volume, and the second modifier solution may be a modifier solution having a second concentration and a second volume. The modifier in the modifier solution may be a surfactant (e.g., octanoic acid) capable of modifying the surface of silver particles. In some examples, the modifier solution may be an anhydrous ethanol solution of octanoic acid.

[0034] Specifically, the second concentration can be greater than or equal to the first concentration, and the second volume can be greater than or equal to the first volume of the first modifier solution, wherein the first volume can be 25 to 150 mL, for example, 50 mL or 100 mL, and the first concentration can be 5.08 to 6.5 g / L, for example, 6.3 g / L.

[0035] In some examples, the second concentration may be equal to the first concentration, and the second volume may be equal to the first volume. For example, the second concentration and the first concentration may both be 6.3 g / L, the second volume and the first volume may both be 50 mL, or may both be 100 mL, in other words, the first modifier solution and the second modifier solution may both be 50 mL of a 6.3 g / L modifier solution, or may both be 100 mL of a 6.3 g / L modifier solution.

[0036] In other examples, the second concentration may be greater than the first concentration, for example, may be twice the first concentration, and the second volume may be equal to the first volume. For example, the second concentration and the first concentration may be 6.3 g / L and 12.6 g / L, respectively, and the second volume and the first volume may both be 100 mL, in other words, the first modifier solution and the second modifier solution may be 100 mL of the 6.3 g / L modifier solution and 100 mL of the 12.6 g / L modifier solution, respectively.

[0037] In this embodiment, the mass ratio of silver nitrate in the silver nitrate solution to the mass ratio of the modifier in the first modifier solution can be 196.85 to 153.8, for example, 158.73. The mass ratio of silver nitrate in the silver nitrate solution to the mass ratio of the reducing agent in the reducing agent solution can be 1.8 to 1.95, for example, 1.82. The mass ratio of silver nitrate in the silver nitrate solution to the mass ratio of the neutralizer in the neutralizer solution can be 6.2 to 7.2, for example, 6.7.

[0038] Specifically, the neutralizer in the neutralizer solution may include one or more of polyvinyl pyrrolidone, polyacrylic acid, polyvinyl alcohol and methyl acrylate, for example, polyvinyl pyrrolidone. The reducing agent in the reducing agent solution may include one or more of L-ascorbic acid, glucose, sodium borohydride, formaldehyde, hydrazine hydrate, hydroquinone, alkanolamine and hydrogen peroxide, for example, L-ascorbic acid.

[0039] In some embodiments, preparing a silver nitrate solution, a reducing agent solution, and a neutralizing agent solution may include: dissolving silver nitrate in deionized water to obtain a silver nitrate solution with a concentration of 80 to 120 g / L; dissolving L-ascorbic acid as a reducing agent in deionized water to obtain a reducing agent solution with a concentration of 55 to 82.5 g / L; and dissolving polyvinyl pyrrolidone as a neutralizing agent in deionized water to obtain a neutralizing agent solution with a concentration of 12 to 18 g / L.

[0040] Wherein, the conductivity of the deionized water used to prepare the above-mentioned silver nitrate solution, reducing agent solution and neutralizing agent solution may be less than or equal to 2 μS / cm.

[0041] In some embodiments, preparing the first modifier solution and the second modifier solution may include: dissolving octanoic acid as a modifier in anhydrous ethanol to obtain a modifier solution with a concentration of 5.08 to 6.5 g / L, and evenly dividing the modifier solvent into two parts to obtain the first modifier solution and the second modifier solution; or, it may include: dissolving two parts of octanoic acid as a modifier in anhydrous ethanol respectively to obtain the first modifier solution and the second modifier solution.

[0042] Furthermore, it should be noted that in this embodiment, by changing the concentration and volume of the first modifier solution and the second modifier solution, the modification effect of the silver powder particles can be adjusted to meet different requirements of the organic phase.

[0043] Step S12: After adding the silver nitrate solution and the reducing agent solution to the neutralizer solution, the first modifier solution is added to perform a first modification treatment to obtain a first modified silver powder suspension.

[0044] In this embodiment, step S12 may include: stirring the neutralizer solution, and during the stirring process, after adding the silver nitrate solution and the reducing agent solution to the neutralizer solution, adding the first modifier solution within a preset addition time for a first modification treatment to obtain a first modified silver powder suspension. The preset addition time may be less than or equal to 1 minute, for example, may be 1 minute, so that the first modifying solution is added immediately after the silver nitrate solution and the reducing agent solution are added, so that during the redox reaction, the surface of the silver powder particles generated by the redox reaction can be modified to obtain a first modified silver powder suspension to ensure the modification effect.

[0045] Moreover, in the specific implementation, the neutralizer solution can be used as the base liquid, and the base liquid is stirred at a high speed, and the stirring speed can be 1000-1500rmp, and the above-mentioned silver nitrate solution and reducing agent solution are added to the base liquid stirred at a high speed. After the above-mentioned silver nitrate solution and reducing agent solution are added, the above-mentioned first modification solution is immediately added to perform the first modification treatment to obtain a first modified silver powder suspension.

[0046] Specifically, the addition time of the silver nitrate solution and the reducing agent solution can be controlled to be 3 to 4 minutes (for example, 3 minutes), that is, the silver nitrate solution and the reducing agent solution can be added to the bottom solution within 3 to 4 minutes. The reaction temperature of the first modification treatment can be 30 to 45°C, for example, 30°C, 35°C, 40°C or 45°C.

[0047] Step S13: separating the primary modified silver powder from the primary modified silver powder suspension.

[0048] In this embodiment, step S13 may include: performing solid-liquid separation after settling the primary modified silver powder suspension, and washing, drying and sieving the separated solid to obtain the primary modified silver powder.

[0049] Furthermore, in a specific implementation, the first modified silver powder suspension can be settled and then solid-liquid separated, and the separated solid can be washed by a centrifuge, the frequency of which is controlled at 15-25 Hz, and the washing includes: washing with deionized water and washing with anhydrous ethanol 1-2 times. Then, the washed solid is dried, the drying temperature can be 75-85°C, the drying time can be 3 hours, and the dried solid can be sieved with a preset mesh to obtain a first modified silver powder, wherein the preset mesh can be greater than or equal to 30 meshes.

[0050] Step S14: After adding the first modified silver powder to the dispersion solvent, add the second modifier solution to perform a second modification treatment to obtain a second modified silver powder suspension.

[0051] In this embodiment, step S14 may include: stirring the dispersion solvent, and during the stirring process, after adding the first modified silver powder to the dispersion solvent, adding the second modifier solution to perform a second modification treatment to obtain a second modified silver powder suspension.

[0052] Moreover, in the specific implementation, the dispersion solvent (for example, anhydrous ethanol) can be stirred at a high speed of 1000-1500 rpm for 1 hour, and the first modified silver powder is added to the dispersion solvent stirred at a high speed. After the first modified silver powder is added, the second modified solution is added for a second modification to obtain a second modified silver powder suspension.

[0053] The primary modified silver powder may be insoluble in the dispersion solvent, or its solubility in the dispersion solvent is very small and can be ignored. In addition, the mass ratio of the primary modified silver powder to the dispersion solvent may be 0.4 to 0.66. In some examples, the dispersion solvent may be 158 g of anhydrous ethanol.

[0054] In addition, it should be noted that, compared with the once-modified silver powder, the second-modified silver powder obtained by modifying the once-modified silver powder again in this embodiment has the advantages of higher tap density, lower burn-in loss, normal particle size distribution, better dispersion in organic carriers, better printability, and higher filling rate.

[0055] Step S15: separating the secondary modified silver powder from the secondary modified silver powder suspension, wherein the secondary modified silver powder is porous spherical silver powder.

[0056] In this embodiment, step S15 may include: centrifuging the secondary modified silver powder suspension to dry it, and drying and grinding the solid obtained by centrifugal drying to obtain the secondary modified silver powder.

[0057] Moreover, in the specific implementation, the above-mentioned secondary modified silver powder suspension can be dried using a centrifuge, and the solid obtained by drying can be dried. The drying temperature can be controlled at 75-85°C, and the drying time can be 3 hours. The dried solid is then ground to obtain the target product (that is, the above-mentioned secondary modified silver powder).

[0058] It should be noted that the porous spherical silver powder obtained after the completion of the above step 15 can improve the printability of the conductive paste due to its spherical shape, and has a higher specific surface area. Moreover, due to its porous structure, it has higher activity, so it has better comprehensive electrical properties.

[0059] In some embodiments, the porous spherical silver powder (i.e., secondary modified silver powder) obtained after the above step 15 is completed may have a particle size of 2.0 to 3.0 μm and a specific surface area of ​​0.2 to 0.4 m 2 / g, for example, it can be 0.35m 2 / g.

[0060] Furthermore, for ease of understanding, the present application is further described in detail below through three specific embodiments (ie, embodiment 1, embodiment 2 and embodiment 3), and comparative examples 1, 2 and 3 are used as controls.

[0061] Example 1

[0062] In Example 1, the specific process of the preparation method of porous quasi-spherical silver powder can be as follows:

[0063] Step S21. Prepare a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution, including: dissolving 55g of ascorbic acid as a reducing agent in deionized water and adjusting the volume to 1L to obtain a reducing agent solution; dissolving 100g of silver nitrate in deionized water and adjusting the volume to 1L to obtain a silver nitrate solution; dissolving 15g of polyvinyl pyrrolidone as a neutralizing agent in deionized water and adjusting the volume to 1L to obtain a neutralizer solution; dissolving 0.63g of octanoic acid in anhydrous ethanol, adjusting the volume to 100ml and then evenly dividing into two parts to obtain a first modifier solution and a second modifier solution.

[0064] Step S22. Reaction stage, including: stirring the above-mentioned neutralizer solution at a high speed of 1000rpm, and during the stirring process, adding the above-mentioned silver nitrate solution and the reducing agent solution to the above-mentioned neutralizer solution at the same time, the adding time of the above-mentioned silver nitrate solution and the reducing agent solution is 3min, after the above-mentioned silver nitrate solution and the reducing agent solution are added, immediately add the above-mentioned first modifying solution for the first modification treatment to obtain a first modified silver powder suspension; after the first modified silver powder suspension is settled, solid-liquid separation is performed, and the separated solid is centrifuged and washed at a frequency of 15Hz and a washing time of 30min, the centrifugal washing includes adding 1L of ethanol and centrifuging for 5min, and then transferring the solid after centrifugal washing to an oven for drying, the drying temperature is 80℃, and the drying time is 3h. After the drying is completed, a 30-mesh sieve is selected to sieve to obtain a first modified silver powder.

[0065] Step S23. secondary modification, comprising: stirring 158 g of anhydrous ethanol at a high speed of 1000 rpm for 1 h, and during the stirring process, sequentially adding the above-mentioned once-modified silver powder and the second modifier solution to 158 g of anhydrous ethanol for a second modification to obtain a secondary modified silver powder suspension; using a centrifuge to spin dry the above-mentioned secondary modified silver powder suspension at a centrifugal frequency of 15 Hz for 30 min, and transferring the dried solid to an oven for drying, the drying temperature is set to 80°C, the drying time is set to 3 h, and then grinding the dried solid to obtain silver powder A1 which is a porous spherical silver powder.

[0066] Example 2

[0067] In Example 2, the specific process of the preparation method of porous quasi-spherical silver powder can be as follows:

[0068] Step S31. Prepare a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution, including: dissolving 55g of ascorbic acid as a reducing agent in deionized water and adjusting the volume to 1L to obtain a reducing agent solution; dissolving 100g of silver nitrate in deionized water and adjusting the volume to 1L to obtain a silver nitrate solution; dissolving 15g of polyvinyl pyrrolidone as a neutralizing agent in deionized water and adjusting the volume to 1L to obtain a neutralizer solution; dissolving 1.26g of octanoic acid in anhydrous ethanol, adjusting the volume to 200ml and then evenly dividing into two portions to obtain a first modifier solution and a second modifier solution.

[0069] Step S32. Reaction stage, including: stirring the above-mentioned neutralizer solution at a high speed of 1000rpm, and during the stirring process, adding the above-mentioned silver nitrate solution and the reducing agent solution to the above-mentioned neutralizer solution at the same time, the adding time of the above-mentioned silver nitrate solution and the reducing agent solution is 3min, after the above-mentioned silver nitrate solution and the reducing agent solution are added, immediately add the above-mentioned first modification solution for the first modification treatment to obtain a first modified silver powder suspension; after the first modified silver powder suspension is settled, solid-liquid separation is performed, and the separated solid is centrifuged and washed at a frequency of 15Hz and a washing time of 30min, the centrifugal washing includes adding 1L of ethanol and centrifuging for 5min, and then transferring the solid after centrifugal washing to an oven for drying, the drying temperature is 80℃, and the drying time is 3h. After the drying is completed, a 30-mesh sieve is selected to sieve to obtain a first modified silver powder.

[0070] Step S33. secondary modification, comprising: stirring 158g of anhydrous ethanol at a high speed of 1000rpm for 1h, and during the stirring process, sequentially adding the above-mentioned once-modified silver powder and the second modifier solution to 158g of anhydrous ethanol for a second modification to obtain a secondary modified silver powder suspension; using a centrifuge to spin dry the above-mentioned secondary modified silver powder suspension at a centrifugal frequency of 15hz for 30min, and transferring the dried solid to an oven for drying, the drying temperature is set to 80°C, the drying time is set to 3h, and then grinding the dried solid to obtain silver powder A2 which is a porous spherical silver powder.

[0071] Example 3

[0072] In Example 3, the specific process of the preparation method of porous spherical silver powder can be as follows:

[0073] Step S41. Prepare a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution, including: dissolving 55g of ascorbic acid as a reducing agent in deionized water and adjusting the volume to 1L to obtain a reducing agent solution; dissolving 100g of silver nitrate in deionized water and adjusting the volume to 1L to obtain a silver nitrate solution: dissolving 15g of polyvinyl pyrrolidone as a neutralizing agent in deionized water and adjusting the volume to 1L to obtain a neutralizer solution; dissolving 0.63g of octanoic acid in anhydrous ethanol and adjusting the volume to 100ml to obtain a first modifier solution; dissolving 1.26g of octanoic acid in anhydrous ethanol and adjusting the volume to 100ml to obtain a second modifier solution.

[0074] Step S42. Reaction stage, including: stirring the above-mentioned neutralizer solution at a high speed of 1000rpm, and during the stirring process, adding the above-mentioned silver nitrate solution and the reducing agent solution to the above-mentioned neutralizer solution at the same time, the adding time of the above-mentioned silver nitrate solution and the reducing agent solution is 3min, after the above-mentioned silver nitrate solution and the reducing agent solution are added, immediately add the above-mentioned first modification solution for the first modification treatment to obtain a first modified silver powder suspension; after the first modified silver powder suspension is settled, solid-liquid separation is carried out, and the separated solid is centrifuged and washed at a frequency of 15Hz and a washing time of 30min, the centrifugal washing includes adding 1L of ethanol and centrifuging for 5min, and then transferring the solid after centrifugal washing to an oven for drying, the drying temperature is 80℃, and the drying time is 3h. After the drying is completed, a 30-mesh sieve is selected to sieve to obtain a first modified silver powder.

[0075] Step S43. secondary modification, comprising: stirring 158 g of anhydrous ethanol at a high speed of 1000 rpm for 1 h, and during the stirring process, sequentially adding the above-mentioned once-modified silver powder and the second modifier solution to 158 g of anhydrous ethanol for a second modification to obtain a secondary modified silver powder suspension; using a centrifuge to spin dry the above-mentioned secondary modified silver powder suspension at a centrifugal frequency of 15 Hz for 30 min, and transferring the dried solid to an oven for drying, the drying temperature is set to 80°C, the drying time is set to 3 h, and then grinding the dried solid to obtain silver powder A3 which is a porous spherical silver powder.

[0076] Comparative Example 1

[0077] In Comparative Example 1, the specific process of the preparation method of porous spherical silver powder can be as follows:

[0078] Step S51. Prepare a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution, including: dissolving 55g of ascorbic acid as a reducing agent in deionized water and adjusting the volume to 1L to obtain a reducing agent solution; dissolving 100g of silver nitrate in deionized water and adjusting the volume to 1L to obtain a silver nitrate solution; dissolving 7.5g of polyvinyl pyrrolidone as a neutralizer in deionized water and adjusting the volume to 1L to obtain a neutralizer solution; dissolving 1.26g of octanoic acid in anhydrous ethanol, adjusting the volume to 200ml and then evenly dividing into two portions to obtain a first modifier solution and a second modifier solution.

[0079] Step S52. Reaction stage, including: stirring the above-mentioned neutralizer solution at a high speed of 1000rpm, and during the stirring process, adding the above-mentioned silver nitrate solution and the reducing agent solution to the above-mentioned neutralizer solution at the same time, the adding time of the above-mentioned silver nitrate solution and the reducing agent solution is 3min, after the above-mentioned silver nitrate solution and the reducing agent solution are added, immediately add the above-mentioned first modification solution for the first modification treatment to obtain a first modified silver powder suspension; after the first modified silver powder suspension is settled, solid-liquid separation is carried out, and the separated solid is centrifuged and washed at a frequency of 15Hz and a washing time of 30min, the centrifugal washing includes adding 1L of ethanol and centrifuging for 5min, and then transferring the solid after centrifugal washing to an oven for drying, the drying temperature is 80℃, and the drying time is 3h. After the drying is completed, a 30-mesh sieve is selected to sieve to obtain a first modified silver powder.

[0080] Step S53. secondary modification, including: high-speed stirring of 158g of anhydrous ethanol, the stirring speed is 1000rpm, the stirring time is 1h, and during the stirring process, the above-mentioned primary modified silver powder and the second modifier solution are sequentially added to 158g of anhydrous ethanol for a second modification treatment to obtain a secondary modified silver powder suspension; the secondary modified silver powder suspension is dried using a centrifuge, the centrifugal frequency is 15hz, the time is 30min, and the dried solid is transferred to an oven for drying, the drying temperature is set to 80°C, the drying time is set to 3h, and then the dried solid is ground to obtain silver powder B1.

[0081] Comparative Example 2

[0082] In Comparative Example 2, the specific process of the preparation method of porous spherical silver powder can be as follows:

[0083] Step S61. Prepare a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution, including: dissolving 55g of ascorbic acid as a reducing agent in deionized water and adjusting the volume to 1L to obtain a reducing agent solution; dissolving 100g of silver nitrate in deionized water and adjusting the volume to 1L to obtain a silver nitrate solution: dissolving 15g of polyvinyl pyrrolidone as a neutralizing agent in deionized water and adjusting the volume to 1L to obtain a neutralizer solution; dissolving 0.63g of octanoic acid in anhydrous ethanol and adjusting the volume to 100ml to obtain a first modifier solution.

[0084] Step S62. Reaction stage, including: stirring the above-mentioned neutralizer solution at a high speed of 1000rpm, and during the stirring process, adding the above-mentioned silver nitrate solution and the reducing agent solution to the above-mentioned neutralizer solution at the same time, the adding time of the above-mentioned silver nitrate solution and the reducing agent solution is 3min, after the above-mentioned silver nitrate solution and the reducing agent solution are added, immediately add the above-mentioned first modifying solution for the first modification treatment to obtain a first modified silver powder suspension; after the first modified silver powder suspension is settled, solid-liquid separation is carried out, and the separated solid is centrifuged and washed at a frequency of 15Hz and a washing time of 30min, the centrifugal washing includes adding 1L of ethanol and centrifuging for 5min, and then transferring the solid after centrifugal washing to an oven for drying, the drying temperature is 80℃, and the drying time is 3h. After the drying is completed, a 30-mesh sieve is selected to sieve to obtain a first modified silver powder.

[0085] Step S63. Other treatments, including: high-speed stirring of 158 g of anhydrous ethanol, the stirring speed is 1000 rpm, the stirring time is 1 hour, and during the stirring process, the above-mentioned once-modified silver powder is added to 158 g of anhydrous ethanol to obtain a solid-liquid mixture; the solid-liquid mixture is dried using a centrifuge, the centrifugal frequency is 15 Hz, the time is 30 minutes, and the dried solid is transferred to an oven for drying, the drying temperature is set to 80°C, the drying time is set to 3 hours, and then the dried solid is ground to obtain silver powder B2.

[0086] Comparative Example 3

[0087] In Comparative Example 3, the specific process of the preparation method of porous spherical silver powder can be as follows:

[0088] Step S71. Prepare a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution, including: dissolving 55g of ascorbic acid as a reducing agent in deionized water and adjusting the volume to 1L to obtain a reducing agent solution; dissolving 100g of silver nitrate in deionized water and adjusting the volume to 1L to obtain a silver nitrate solution: dissolving 15g of polyvinyl pyrrolidone as a neutralizing agent in deionized water and adjusting the volume to 1L to obtain a neutralizer solution; dissolving 0.63g of caprylic acid in anhydrous ethanol and adjusting the volume to 100ml to obtain a first modifier solution.

[0089] Step S72. Reaction stage, including: stirring the above-mentioned neutralizer solution at a high speed of 1000rpm, and during the stirring process, adding the above-mentioned silver nitrate solution and the reducing agent solution to the above-mentioned neutralizer solution at the same time, the adding time of the above-mentioned silver nitrate solution and the reducing agent solution is 3min, after the above-mentioned silver nitrate solution and the reducing agent solution are added, immediately add the above-mentioned first modification solution for the first modification treatment to obtain a modified silver powder suspension; after the first modified silver powder suspension is settled, solid-liquid separation is carried out, and the separated solid is centrifuged and washed at a frequency of 15Hz and a washing time of 30min, the centrifugal washing includes adding 1L of ethanol and centrifuging for 5min, and then transferring the solid after centrifugal washing to an oven for drying, the drying temperature is 80°C, and the drying time is 3h, and then the dried solid is ground to obtain silver powder B3.

[0090] Specifically, by testing the silver powder A1, silver powder A2 and silver powder A3 prepared in the above-mentioned Example 1, Example 2 and Example 3, and the silver powder B1, silver powder B2 and silver powder B3 prepared in the above-mentioned Comparative Example 1, Comparative Example 2 and Comparative Example 3, the parameter results of each silver powder A1 / A2 / A3 / B1 / B2 / B3 are shown in Table 1 below.

[0091] Table 1

[0092]

[0093] And, according to Table 1, Figure 2 and Figure 3 , it can be seen from the comparison between Example 1 and Comparative Example 1 that the difference between Comparative Example 1 and Example 1 is that the amount of polyvinyl pyrrolidone used as a neutralizer is adjusted from 15g to 7.5g, and compared with the silver powder A1 prepared in Example 1, the morphology of the silver powder B1 prepared in Comparative Example 1 has changed significantly, no longer having a porous structure, and its sphericity has also decreased significantly, and the porous structure of the silver powder A1 has obvious advantages in comprehensive electrical properties; it can be seen from the comparison between Example 1 and Comparative Example 2 that the difference between Comparative Example 2 and Example 1 is that no polyvinyl pyrrolidone is used. The second modifier solution performs a second modification treatment on the first modified silver powder, and compared with the silver powder A1 obtained in Example 1, the tap density of the silver powder B2 obtained in Comparative Example 2 is significantly lower; by comparing Example 1 and Comparative Example 3, it can be seen that the difference between Comparative Example 3 and Example 1 is that the second modifier solution is not used to perform a second modification treatment on the first modified silver powder, and a second drying is also performed, and compared with the silver powder A1 obtained in Example 1, the particle size distribution of the silver powder B3 obtained in Comparative Example 3 changes, and its particle size distribution is wider. It can be seen that the second modified silver powder obtained in the embodiment of the present application has a higher tap density and a narrower particle size distribution of particle size D10 / D50 / D90.

[0094] Furthermore, by dispersing the silver powder A1, silver powder A2 and silver powder A3 prepared in the above-mentioned Example 1, Example 2 and Example 3, and the silver powder B1, silver powder B2 and silver powder B3 prepared in the above-mentioned Comparative Example 1, Comparative Example 2 and Comparative Example 3 in the organic phase, different conductive silver pastes (i.e., paste A1, paste A2, paste A3, paste B1, paste B2 and paste B3) were obtained accordingly, and each conductive silver paste was tested, and the test results were shown in Table 2 below.

[0095] Table 2

[0096]

[0097] Moreover, it can be seen from Table 2 that, compared with Comparative Example 1, Comparative Example 2 and Comparative Example 3, the viscosity of the slurry A1 corresponding to Example 1 is lower, and its fineness is less than 4, which means that it has better advantages in terms of printability and its filling rate is higher; compared with Comparative Example 2, the slurry A1 corresponding to Example 1 has certain advantages in filling rate. At the same time, because Comparative Example 2 does not use the second modifier solution to perform a second modification treatment on the first modified silver powder, the surface of the silver powder B2 particles prepared in Comparative Example 2 is not sufficiently in contact with the organic, which affects the distribution in the organic, resulting in the fineness and viscosity of the slurry B2 corresponding to Comparative Example 2 being too large, which will reduce its printing performance. Comparing Comparative Example 3 and Example 3, because Comparative Example 3 does not use the second modifier solution to perform a second modification treatment on the first modified silver powder, and also performs a second drying, the fineness of the slurry B3 corresponding to Example 3 is too large, which seriously affects printing and is difficult to have a better application at the slurry end.

[0098] As can be seen from the above, the method for preparing the porous spherical silver powder provided in this embodiment comprises preparing a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizer solution, adding the silver nitrate solution and the reducing agent solution to the neutralizer solution, and then adding the first modifier solution to perform a first modification treatment to obtain a first modified silver powder suspension, and then separating the first modified silver powder from the first modified silver powder suspension, and adding the first modified silver powder to a dispersing solvent, and then adding the second modifier solution to perform a second modification treatment to obtain a second modified silver powder suspension. , and then the secondary modified silver powder is separated from the secondary modified silver powder suspension. The secondary modified silver powder is a porous spherical silver powder, so that a porous spherical silver powder with advantages such as lower burn-in loss, higher tap density, better particle size distribution, and better printability can be prepared. Silver powders with different particle sizes, different specific surface areas, and different conductive properties can be obtained according to different application scenarios, and the porous structure of the silver powder particles has higher activity, ensuring that the porous spherical silver powder has better comprehensive electrical properties and can have good application prospects in conductive slurries, conductive coatings, and other fields.

[0099] In order to better implement the method for preparing the porous spherical silver powder provided in the embodiment of the present application, the embodiment of the present application also provides a porous spherical silver powder (such as Figure 2 As shown), the porous spherical silver powder is prepared by the preparation method of the porous spherical silver powder provided by any of the above embodiments.

[0100] Furthermore, it should be noted that the porous spherical silver powder in the embodiment of the present application is prepared by adopting the preparation method of the porous spherical silver powder provided by any of the above embodiments, and therefore has all the same beneficial effects, which will not be described in detail in this embodiment.

[0101] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0102] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing porous spherical silver powder, characterized in that: include: Prepare a first modifier solution, a second modifier solution, a silver nitrate solution, a reducing agent solution and a neutralizing agent solution, wherein the first modifier solution is a modifier solution having a first concentration and a first volume, the second modifier solution is a modifier solution having a second concentration and a second volume, and the second concentration is greater than or equal to the first concentration, the second volume is greater than or equal to the first volume, the first concentration is 5.08 to 6.5 g / L, the concentration of the silver nitrate solution is 80 to 120 g / L, the concentration of the reducing agent solution is 55 to 82.5 g / L, and the concentration of the neutralizing agent solution is 12 to 18 g / L; After adding the silver nitrate solution and the reducing agent solution to the neutralizing agent solution, adding the first modifier solution to perform a first modification treatment to obtain a first modified silver powder suspension; Separating the primary modified silver powder from the primary modified silver powder suspension; After adding the first modified silver powder to the dispersion solvent, adding the second modifier solution to perform a second modification treatment to obtain a second modified silver powder suspension; Secondary modified silver powder is separated from the secondary modified silver powder suspension, and the secondary modified silver powder is porous spherical silver powder.

2. The preparation method according to claim 1, characterized in that: The modifier solution is an absolute ethanol solution of octanoic acid.

3. The preparation method according to claim 1, characterized in that: The ratio of the mass of silver nitrate in the silver nitrate solution to the mass of the modifier in the first modifier solution is 196.85 to 153.

8.

4. The preparation method according to claim 1, characterized in that: The step of separating the primary modified silver powder from the primary modified silver powder suspension comprises: The first modified silver powder suspension is settled and then solid-liquid separation is performed, and the separated solid is washed, dried and sieved to obtain the first modified silver powder.

5. The preparation method according to claim 1, characterized in that: After adding the first modified silver powder to the dispersion solvent, adding the second modifier solution to perform a second modification treatment to obtain a second modified silver powder suspension, comprising: The dispersion solvent is stirred, and during the stirring process, after the first modified silver powder is added to the dispersion solvent, the second modifier solution is added to perform a second modification treatment to obtain a second modified silver powder suspension.

6. The preparation method according to claim 1, characterized in that: The step of separating the secondary modified silver powder from the secondary modified silver powder suspension comprises: The secondary modified silver powder suspension is centrifuged and dried, and the solid obtained by centrifugal drying is dried and ground to obtain the secondary modified silver powder.

7. The preparation method according to claim 1, characterized in that: After adding the silver nitrate solution and the reducing agent solution to the neutralizer solution, adding the first modifier solution to perform a first modification treatment to obtain a first modified silver powder suspension, comprising: The neutralizer solution is stirred, and during the stirring process, the silver nitrate solution and the reducing agent solution are added to the neutralizer solution, and then the first modifier solution is added within a preset addition time for a first modification treatment to obtain a first modified silver powder suspension, wherein the preset addition time is less than or equal to 1 min.

8. A porous spherical silver powder, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 7.

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