Wool ball-shaped silver powder and preparation method thereof

Abstract

The present application relates to a woolen ball-shaped silver powder and a preparation method thereof. The preparation method of the woolen ball-shaped silver powder comprises: adding a crystal cell regulator and a dispersant to a reducing agent solution to prepare a first solution; adding a silver nitrate solution to the first solution in a static state to react and obtain a silver powder suspension; separating the woolen ball-shaped silver powder from the silver powder suspension, wherein the woolen ball-shaped silver powder is formed by the aggregation and entanglement of linear silver powders, thereby preparing a woolen ball-shaped silver powder with a large specific surface area; the morphology and size of the woolen ball-shaped silver powder can be effectively regulated by changing the reaction temperature and / or the amount and type of the crystal cell regulator; and the woolen ball-shaped structure can effectively avoid agglomeration and bridging effects, thereby ensuring good dispersibility and uniformity of the woolen ball-shaped silver powder, and having good application prospects in conductive pastes, conductive coatings and other fields.

Description

Technical Field

[0001] The present application relates to the technical field of preparation of new precious metal materials, and in particular to a woolen ball-shaped silver powder and a preparation method thereof. Background Art

[0002] Silver has unique catalytic, antibacterial, nonlinear optical, and electrical and thermal conductivity properties, and has broad prospects in the fields of sterile antibacterial agents, catalytic materials, and conductive pastes. The properties and applications of silver powder depend on the size and morphology of silver particles.

[0003] However, the specific surface area of ​​nano-metal particles is limited due to their aggregation and bridging phenomena. Therefore, how to prepare silver particles with a higher specific surface area is a problem that needs to be solved at present and in the future. Summary of the invention

[0004] The purpose of the present application is to provide a woolen ball-shaped silver powder and a preparation method thereof, so as to prepare woolen ball-shaped silver powder with a large specific surface area, thereby having good application prospects in multiple fields such as conductive pastes and conductive coatings.

[0005] The present application provides a method for preparing a wool ball-shaped silver powder, and the method for preparing a wool ball-shaped silver powder comprises:

[0006] Adding a unit cell regulator and a dispersant to a reducing agent solution to prepare a first solution;

[0007] In a static state, adding a silver nitrate solution into the first solution to react and obtain a silver powder suspension;

[0008] The woolen ball-shaped silver powder is separated from the silver powder suspension, and the woolen ball-shaped silver powder is formed by the aggregation and entanglement of the thread-shaped silver powder.

[0009] Wherein, the unit cell regulator includes at least one of ammonia water, sodium citrate, potassium citrate, citric acid, potassium sulfate, sodium carbonate and nitric acid.

[0010] The ratio of the mass of the unit cell regulator to the mass of silver nitrate in the silver nitrate solution is 1-20%.

[0011] The method of adding the silver nitrate solution to the first solution for reaction to obtain the silver powder suspension comprises: adding the silver nitrate solution to the first solution for reaction under a preset reaction temperature condition to obtain the silver powder suspension, wherein the preset reaction temperature is 0-30°C.

[0012] The step of adding the silver nitrate solution into the first solution for reaction to obtain the silver powder suspension comprises: adding the silver nitrate solution into the first solution for reaction within a preset adding time to obtain the silver powder suspension, wherein the preset adding time is less than 4 seconds.

[0013] The method of separating woolen ball-shaped silver powder from a silver powder suspension comprises: performing solid-liquid separation on the silver powder suspension, washing the separated solid, and drying the washed solid at a preset drying temperature and a preset drying time to obtain woolen ball-shaped silver powder, wherein the preset drying temperature is 50-90°C, and the preset drying time is 20-60min.

[0014] Among them, the diameter of the linear silver powder is nanometer level.

[0015] The particle size D50 of the wool ball-shaped silver powder is 0.5 to 4.0 μm, and the tap density of the wool ball-shaped silver powder is greater than or equal to 5.5 g / cm 3 .

[0016] The pH value of the reducing agent solution is 1-5, the pH value of the first solution is 0.1-6, and the pH value of the silver nitrate solution is 2-6.

[0017] The embodiment of the present application also provides a woolen ball-shaped silver powder, which is prepared by any of the above-mentioned methods for preparing woolen ball-shaped silver powder.

[0018] The woolen ball-shaped silver powder and the preparation method thereof provided in the present application are as follows: a first solution is prepared by adding a unit cell regulator and a dispersant to a reducing agent solution, and then a silver nitrate solution is added to the first solution in a static state for reaction to obtain a silver powder suspension, and the woolen ball-shaped silver powder is separated from the silver powder suspension. The woolen ball-shaped silver powder is formed by the aggregation and entanglement of linear silver powders, so that a woolen ball-shaped silver powder with a large specific surface area can be prepared by a liquid phase one-step reduction method. The woolen ball-shaped silver powder has the advantages of fewer influencing factors in the reaction process, simple preparation process, and high feasibility of mass production. The woolen ball-shaped structure can effectively avoid agglomeration and bridging effects, thereby ensuring good dispersion and uniformity of the woolen ball-shaped silver powder, and has good application prospects in conductive slurries, conductive coatings and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figure 1 It is a schematic diagram of the process of preparing wool ball-shaped silver powder provided in an embodiment of the present application;

[0021] Figure 2 is a scanning electron microscope image of the wool ball-shaped silver powder prepared by the method for preparing the wool ball-shaped silver powder provided in Example 1 of the present application;

[0022] Figure 3 is a scanning electron microscope image of the wool ball-shaped silver powder prepared by the method for preparing wool ball-shaped silver powder provided in Example 2 of the present application;

[0023] Figure 4 is a scanning electron microscope image of the wool ball-shaped silver powder prepared by the method for preparing wool ball-shaped silver powder provided in Example 3 of the present application;

[0024] Figure 5 This is a scanning electron microscope image of the woolen ball-shaped silver powder prepared by the method for preparing woolen ball-shaped silver powder provided in Example 4 of the present application. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Silver has unique catalytic, antibacterial, nonlinear optical, and electrical and thermal conductivity properties, and has broad prospects in the fields of sterile antibacterial agents, catalytic materials, and conductive pastes. The properties and applications of silver powder depend on the size and morphology of silver particles.

[0030] However, due to the agglomeration and bridging phenomena of nano-metal particles, their nano-effect and specific surface area are limited. Therefore, how to prepare silver particles with better nano-effect and higher specific surface area is a problem that needs to be solved at present and in the future.

[0031] In response to the above problems, Chinese patent CN104985190B discloses a method for synthesizing flower-shaped silver micron particles, which prepares micron-sized silver powder with a flower-shaped structure by separately preparing an oxidizing solution and a reducing solution, then adding the reducing solution to the oxidizing solution, and immediately adding a stainless steel sheet and starting to stir. However, this synthesis method has specific requirements for the size and morphology of the stainless steel sheet, and air needs to be introduced during the process, which has the problems of poor experimental stability and large morphological differences between batches.

[0032] In view of the above problems, Chinese patent CN101579746B discloses a method for preparing pine cone-shaped micron-sized silver powder, in which a reducing solution is poured into an oxidizing solution under stirring to prepare pine cone-shaped silver powder. The preparation method of this method is simple, but the pine cone-shaped silver powder has high crystallinity and small specific surface area, which has great limitations for use in conductive slurries or catalytic materials.

[0033] In response to the above problems, an embodiment of the present application provides a woolen ball-shaped silver powder and a preparation method thereof, wherein a first solution is prepared by adding a crystal cell regulator and a dispersant to a reducing agent solution, and then a silver nitrate solution is added to the first solution under static conditions to react to obtain a silver powder suspension, and the woolen ball-shaped silver powder is separated from the silver powder suspension. The woolen ball-shaped silver powder is formed by the aggregation and entanglement of linear silver powders, thereby preparing a woolen ball-shaped silver powder with a large specific surface area, and the woolen ball-shaped structure can effectively avoid agglomeration and bridging effects, thereby ensuring good dispersibility and uniformity of the woolen ball-shaped silver powder, and has good application prospects in conductive pastes, conductive coatings and other fields.

[0034] 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.

[0035] See also Figure 1 , Figure 1 : is a schematic diagram of a method for preparing a wool ball-shaped silver powder provided in an embodiment of the present application. The specific process of the method for preparing a wool ball-shaped silver powder can be as follows:

[0036] Step S11. Adding a unit cell regulator and a dispersant into a reducing agent solution to prepare a first solution.

[0037] Step S12: In a static state, add the silver nitrate solution into the first solution to react and obtain a silver powder suspension.

[0038] In this embodiment, adding the silver nitrate solution into the first solution for reaction in a static state may refer to: adding the silver nitrate solution into the first solution for reaction without stirring.

[0039] In some embodiments, the unit cell regulator may include at least one of aqueous ammonia, sodium citrate, potassium citrate, citric acid, potassium sulfate, sodium carbonate and nitric acid.

[0040] In some examples, the unit cell regulator may be nitric acid, for example, 50 mL of nitric acid, or 150 mL. In other examples, the unit cell regulator may be ammonia water, for example, 50 mL of ammonia water.

[0041] In addition, it should be noted that in this embodiment, by adding a crystal cell regulator to the reducing agent solution, the crystal cell regulator can affect the speed of the redox reaction occurring in the above step S12. Therefore, in this embodiment, by adjusting the amount and type of the crystal cell regulator added to the reducing agent solution, it is possible to control the speed of the redox reaction occurring in the above step S12, so as to effectively regulate the size and morphology of the silver powder crystal cells generated by the redox reaction.

[0042] In some embodiments, the dispersant may include at least one of polyethylene glycol, polyvinyl alcohol, gelatin, sodium dodecylbenzene sulfonate, Tween 80, polyvinyl pyrrolidone and gum arabic.

[0043] In some examples, the dispersant may be polyvinyl pyrrolidone, for example, 0.1 kg of polyvinyl pyrrolidone.

[0044] In some embodiments, the reducing agent in the reducing agent solution may include at least one of glucose, sodium borohydride, formaldehyde, ascorbic acid, hydrazine hydrate, hydroquinone, alkanolamine and hydrogen peroxide.

[0045] In some examples, the reducing agent in the reducing agent solution may be ascorbic acid.

[0046] In some examples, the mass fraction of the reducing agent in the reducing agent solution may be 4.6%. In addition, in order to obtain a reducing agent solution with a mass fraction of 4.6%, before the above step S11, the method for preparing the wool ball-shaped silver powder may further include: weighing 0.86 kg of ascorbic acid as a reducing agent and dissolving it in deionized water to prepare a reducing agent solution with a mass fraction of 4.6%.

[0047] In some embodiments, the mass fraction of silver nitrate in the above silver nitrate solution can be 3% to 25%, for example, 3%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23% or 25%, etc.

[0048] In some examples, the mass fraction of silver nitrate in the silver nitrate solution may be 8%. In addition, in order to obtain a silver nitrate solution with a mass fraction of 8%, before the above step S11, the above method for preparing wool ball-shaped silver powder may further include: weighing 1.6 kg of silver nitrate solid and dissolving it in deionized water to prepare a silver nitrate solution with a mass fraction of 8%.

[0049] In some embodiments, the ratio of the mass of the unit cell regulator to the mass of silver nitrate in the silver nitrate solution may be 1-20%, for example, 1%, 5%, 10%, 15% or 20%.

[0050] In some embodiments, the ratio of the mass of the above-mentioned dispersant to the mass of silver nitrate in the silver nitrate solution can be 1-30%, for example, it can be 1%, 6.25%, 10%, 15%, 20%, 25% or 30%, etc.

[0051] In some embodiments, the ratio of the mass of the reducing agent in the reducing agent solution to the mass of the silver nitrate in the silver nitrate solution can be 5-60%, for example, 5, 15%, 25%, 35%, 45%, 53.75% or 60%, etc.

[0052] In some embodiments, the pH value of the reducing agent solution may be 1 to 5. The pH value of the first solution may be 0.1 to 6. The pH value of the silver nitrate solution may be 2 to 6.

[0053] In some embodiments, the step of adding the silver nitrate solution to the first solution to react to obtain the silver powder suspension may specifically include: adding the silver nitrate solution to the first solution to react under a preset reaction temperature to obtain the silver powder suspension. The preset reaction temperature may be 0 to 30°C, for example, 5°C, 10°C, 15°C, or 20°C.

[0054] Furthermore, it should be noted that, in this embodiment, by controlling the reaction temperature of step S12, the morphology of the desired silver powder can be controlled. Specifically, the reaction temperature of step S12 affects the morphology of the silver powder obtained, and the higher the reaction temperature of step S12, the looser the aggregation of the corresponding microcrystalline silver powder.

[0055] In some embodiments, the above-mentioned adding the silver nitrate solution into the first solution for reaction to obtain the silver powder suspension may specifically include: adding the silver nitrate solution into the first solution for reaction within a preset addition time to obtain the silver powder suspension, wherein the preset addition time may be less than 4 seconds, for example, may be 1 second, 2 seconds, 3 seconds or 4 seconds, etc., so as to achieve the goal of quickly pouring the silver nitrate solution into the first solution.

[0056] Step S13. Separate the woolen ball-shaped silver powder from the silver powder suspension, where the woolen ball-shaped silver powder is formed by the aggregation and entanglement of the linear silver powder.

[0057] In this embodiment, the diameter of the above-mentioned linear silver powder can be nanoscale, that is, the above-mentioned woolen spherical silver powder can be formed by the aggregation and winding of linear silver powder with a diameter of nanoscale, for example, it can be formed by the aggregation and winding of linear silver powder with a diameter of about 100nm, thereby ensuring that the prepared woolen spherical silver powder can have both good nano effect and high specific surface area.

[0058] Specifically, after the step S13 is completed, the wool ball-shaped silver powder obtained can be micron-sized, with a particle size D50 of 0.5 to 4.0 μm and a tap density greater than or equal to 5.5 g / cm 3 , thus having good application prospects in many fields such as conductive pastes and conductive coatings.

[0059] In some embodiments, the above step S13 may specifically include: performing solid-liquid separation on the silver powder suspension, washing the separated solid, and drying the washed solid at a preset drying temperature and a preset drying time to obtain woolen ball-shaped silver powder. The preset drying temperature may be 50-90° C., and the preset drying time may be 20-60 min.

[0060] Specifically, after obtaining the above-mentioned silver powder suspension, the above-mentioned silver powder suspension can be separated into solid and liquid, and the separated solid can be washed with deionized water and ethanol and the supernatant can be extracted. The washed solid is then dried at 60°C for 30 minutes and passed through a 500-mesh sieve to obtain the above-mentioned woolen ball-shaped silver powder formed by the aggregation and winding of linear silver powder.

[0061] Furthermore, for ease of understanding, the present application is further described in detail below through four specific embodiments (ie, Embodiment 1, Embodiment 2, Embodiment 3 and Embodiment 4):

[0062] (1) Example 1

[0063] In Example 1, the specific process of the preparation method of wool ball-shaped silver powder can be as follows:

[0064] Step S21. Weigh 1.6 kg of silver nitrate solid and prepare a silver nitrate solution with a mass fraction of 8%.

[0065] Step S22. Weigh 0.86 kg of ascorbic acid as a reducing agent to prepare a reducing agent solution with a mass concentration of 4.6%, and weigh 0.1 kg of polyvinyl pyrrolidone as a dispersant and 50 ml of nitric acid as a unit cell regulator, and add them to the reducing agent solution to prepare a first solution.

[0066] Step S23. Maintain the temperature of the reaction solution at 5°C, and pour the silver nitrate solution into the first solution for reaction in a static state, with the pouring time being 1 s.

[0067] Step S24. Separate the woolen ball-shaped silver powder from the silver powder suspension, where the woolen ball-shaped silver powder is formed by the aggregation and entanglement of the linear silver powder.

[0068] Specifically, the silver powder suspension can be subjected to solid-liquid separation, and the separated solid can be washed with deionized water and ethanol, and then the washed solid can be dried at 60° C. for 30 minutes and then passed through a 500-mesh sieve to obtain silver powder.

[0069] Furthermore, the silver powder obtained after the completion of step S24 is a woolen ball-shaped silver powder formed by the aggregation and winding of linear silver powders, and its particle size D50 is about 1.6 μm and its specific surface area is about 0.8 m 2 / g, and its scanning electron microscope image (such as Figure 2 As shown in the figure, it has uniform morphology and good dispersion.

[0070] (2) Example 2

[0071] The method for preparing the wool ball-shaped silver powder provided in Example 2 is basically the same as the method for preparing the wool ball-shaped silver powder provided in Example 1, and the difference between the two is that the unit cell regulator is adjusted from 50 ml of nitric acid to 150 ml of nitric acid. Accordingly, in Example 2, the specific process of the method for preparing the wool ball-shaped silver powder can be as follows:

[0072] Step S31. Weigh 1.6 kg of silver nitrate solid and prepare a silver nitrate solution with a mass fraction of 8%.

[0073] Step S32. Weigh 0.86 kg of ascorbic acid as a reducing agent to prepare a reducing agent solution with a mass concentration of 4.6%, and weigh 0.1 kg of polyvinyl pyrrolidone as a dispersant and 150 ml of nitric acid as a unit cell regulator, and add them to the reducing agent solution to prepare a first solution.

[0074] Step S33. Maintain the temperature of the reaction solution at 5°C, and pour the silver nitrate solution into the first solution for reaction in a static state, with the pouring time being 1 s.

[0075] Step S34. Separate the woolen ball-shaped silver powder from the silver powder suspension, where the woolen ball-shaped silver powder is formed by the aggregation and entanglement of the linear silver powder.

[0076] Specifically, the silver powder suspension can be subjected to solid-liquid separation, and the separated solid can be washed with deionized water and ethanol, and then the washed solid can be dried at 60° C. for 30 minutes and then passed through a 500-mesh sieve to obtain silver powder.

[0077] Furthermore, the silver powder obtained after the completion of step S34 is a wool ball-shaped silver powder formed by the aggregation and winding of linear silver powders, and its particle size D50 is about 1.7 μm, and its specific surface area is about 1.0 m 2 / g, and its scanning electron microscope image (such as Figure 3 As shown, compared with the silver powder prepared in Example 1, its crystallite is larger, the crystallinity is reduced, and the specific surface area is increased.

[0078] (3) Example 3

[0079] The method for preparing the wool ball-shaped silver powder provided in Example 3 is basically the same as the method for preparing the wool ball-shaped silver powder provided in Example 1, and the difference between the two is that the unit cell regulator is adjusted from 50 ml of nitric acid to 50 ml of ammonia water. Accordingly, in Example 3, the specific process of the method for preparing the wool ball-shaped silver powder can be as follows:

[0080] Step S41. Weigh 1.6 kg of silver nitrate solid and prepare a silver nitrate solution with a mass fraction of 8%.

[0081] Step S42. Weigh 0.86 kg of ascorbic acid as a reducing agent to prepare a reducing agent solution with a mass concentration of 4.6%, and weigh 0.1 kg of polyvinyl pyrrolidone as a dispersant and 50 ml of ammonia water as a cell regulator, and add them to the reducing agent solution to prepare a first solution.

[0082] Step S43. Maintain the temperature of the reaction solution at 5°C, and pour the silver nitrate solution into the first solution for reaction in a static state, with the pouring time being 1 s.

[0083] Step S44. Separate the woolen ball-shaped silver powder from the silver powder suspension, where the woolen ball-shaped silver powder is formed by the aggregation and entanglement of the linear silver powder.

[0084] Specifically, the silver powder suspension can be subjected to solid-liquid separation, and the separated solid can be washed with deionized water and ethanol, and then the washed solid can be dried at 60° C. for 30 minutes and then passed through a 500-mesh sieve to obtain silver powder.

[0085] Furthermore, the silver powder obtained after the completion of step S44 is a woolen ball-shaped silver powder formed by the aggregation and winding of linear silver powders, and its particle size D50 is about 1.4 μm and the specific surface area is about 0.4 m 2 / g, and its scanning electron microscope image (such as Figure 4 As shown, compared with the silver powder prepared in Example 1, its crystallite is smaller, the crystallinity is increased, and the specific surface area is reduced.

[0086] (4) Example 4

[0087] The method for preparing the wool ball-shaped silver powder provided in Example 4 is basically the same as the method for preparing the wool ball-shaped silver powder provided in Example 1, and the difference between the two is that the temperature of the reaction liquid is adjusted from 5° C. to 20° C. Accordingly, in Example 4, the specific process of the method for preparing the wool ball-shaped silver powder can be as follows:

[0088] Step S51. Weigh 1.6 kg of silver nitrate solid and prepare a silver nitrate solution with a mass fraction of 8%.

[0089] Step S52. Weigh 0.86 kg of ascorbic acid as a reducing agent to prepare a reducing agent solution with a mass concentration of 4.6%, and weigh 0.1 kg of polyvinyl pyrrolidone as a dispersant and 50 ml of nitric acid as a unit cell regulator, and add them to the reducing agent solution to prepare a first solution.

[0090] Step S53. Maintain the temperature of the reaction solution at 20°C, and pour the silver nitrate solution into the first solution for reaction in a static state, with the pouring time being 1 s.

[0091] Step S54. Separate the woolen ball-shaped silver powder from the silver powder suspension, where the woolen ball-shaped silver powder is formed by the aggregation and entanglement of the linear silver powder.

[0092] Specifically, the silver powder suspension can be subjected to solid-liquid separation, and the separated solid can be washed with deionized water and ethanol, and then the washed solid can be dried at 60° C. for 30 minutes and then passed through a 500-mesh sieve to obtain silver powder.

[0093] Furthermore, the silver powder obtained after the completion of the above step S54 is a wool ball-shaped silver powder formed by the aggregation and winding of linear silver powders, and its particle size D50 is about 1.4 μm and the specific surface area is about 0.9 m 2 / g, and its scanning electron microscope image (such as Figure 5 As shown in FIG. 1 , it can be seen that compared with the silver powder prepared in Example 1, its crystallinity is reduced and its specific surface area is increased.

[0094] From the above, it can be seen that the preparation method of woolen ball-shaped silver powder provided in this embodiment is to prepare a first solution by adding a crystal cell regulator and a dispersant to a reducing agent solution, and then add a silver nitrate solution to the first solution in a static state to react to obtain a silver powder suspension, and separate the woolen ball-shaped silver powder from the silver powder suspension. The woolen ball-shaped silver powder is formed by the aggregation and entanglement of linear silver powder, so that woolen ball-shaped silver powder with a large specific surface area can be prepared. The morphology and size of the woolen ball-shaped silver powder can be effectively controlled by changing the reaction temperature and / or the amount and type of the crystal cell regulator, and the woolen ball-shaped structure can effectively avoid agglomeration and bridging effects, thereby ensuring good dispersibility and uniformity of the woolen ball-shaped silver powder, and has good application prospects in conductive pastes, conductive coatings and other fields.

[0095] In order to better implement the method for preparing the wool ball-shaped silver powder provided in the embodiment of the present application, the embodiment of the present application also provides a wool ball-shaped silver powder (such as Figure 2 , Figure 3 , Figure 4 or Figure 5 As shown), the woolen ball-shaped silver powder is prepared by the preparation method of the woolen ball-shaped silver powder provided by any of the above embodiments.

[0096] Specifically, the wool ball-shaped silver powder is formed by the aggregation and winding of linear silver powder, wherein the diameter of the linear silver powder can be nanometer-level. That is, the wool ball-shaped silver powder can be formed by the aggregation and winding of linear silver powder with a diameter of nanometer-level, for example, it can be formed by the aggregation and winding of linear silver powder with a diameter of about 100nm, thereby ensuring that the wool ball-shaped silver powder can have both good nano effect and high specific surface area.

[0097] In some embodiments, the particle size of the wool ball-shaped silver powder may be 0.5 to 4.0 μm. The tap density of the wool ball-shaped silver powder may be greater than or equal to 5.5 g / cm 3 The woolen ball-shaped silver powder may have the advantages of uniform morphology, narrow particle size distribution, large specific surface area, and the like.

[0098] Furthermore, the wool ball-shaped silver powder in the embodiment of the present application is prepared by adopting the preparation method of the wool ball-shaped 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.

[0099] 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.

[0100] 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 woolen ball-shaped silver powder, characterized in that: include: Adding a unit cell regulator and a dispersant to a reducing agent solution to prepare a first solution; In a static state, adding a silver nitrate solution to the first solution for reaction to obtain a silver powder suspension; Separating woolen ball-shaped silver powder from the silver powder suspension, wherein the woolen ball-shaped silver powder is formed by the aggregation and winding of linear silver powder; Wherein, the step of adding the unit cell regulator and the dispersant to the reducing agent solution to prepare the first solution comprises: Weigh 0.86 kg of ascorbic acid as a reducing agent to prepare a reducing agent solution with a mass concentration of 4.6%, and weigh 0.1 kg of polyvinyl pyrrolidone as a dispersant and 50 ml of nitric acid as a unit cell regulator, and add them to the reducing agent solution to prepare a first solution; The step of adding a silver nitrate solution to the first solution to react in a static state to obtain a silver powder suspension comprises: Weigh 1.6 kg of silver nitrate solid and prepare a silver nitrate solution with a mass fraction of 8%; The temperature of the reaction solution was maintained at 5° C., and the silver nitrate solution was poured into the first solution in a static state for reaction. The pouring time was 1 s to obtain a silver powder suspension.

2. The preparation method according to claim 1, characterized in that: The method of separating the wool ball-shaped silver powder from the silver powder suspension comprises: The silver powder suspension is subjected to solid-liquid separation, the separated solid is washed, and the washed solid is dried at a preset drying temperature and a preset drying time to obtain woolen ball-shaped silver powder, wherein the preset drying temperature is 50-90° C., and the preset drying time is 20-60 min.

3. The preparation method according to claim 1, characterized in that: The diameter of the linear silver powder is nanometer level.

4. A wool ball-shaped silver powder, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 3.

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