A highly dispersible micro-nano silver powder and its preparation method and application

Abstract

The present invention discloses a highly dispersible micro-nano silver powder and its preparation method and application. The preparation method comprises the following steps: S1. adding a reducing agent solution I and a nucleating agent solution to a dispersant solution I to obtain a mixed solution; S2. adding a silver nitrate solution I to the heated mixed solution for reaction to obtain a reaction mother liquor; S3. adding the reaction mother liquor to a dispersant solution II, and simultaneously adding the silver nitrate solution II and the reducing agent solution II to obtain a reaction mixture; S4. removing impurities, crushing, and sieving the reaction mixture to obtain highly dispersible micro-nano silver powder; the introduction of a nucleating agent controls the release rate of silver ions during the reaction of the reaction mother liquor, providing a sufficient number of uniformly sized crystal nuclei for the subsequent secondary reaction, thereby enabling the production of silver powder after the secondary reaction. The introduction of the dispersant improves the dispersibility of the silver powder, narrows the particle size distribution, and thereby increases the tap density of the silver powder.

Description

Technical Field

[0001] The present invention belongs to the technical field of precious metal powder materials, and in particular relates to a highly dispersible micro-nano silver powder and a preparation method and application thereof. Background Art

[0002] As industry competition becomes increasingly fierce, the requirements of various paste companies for functional silver powder are becoming increasingly stringent, and the printing line type of silver paste is becoming increasingly narrow. As a key material in the development and production of conductive silver paste for solar cells and electronic components, the properties of micro-nano silver powder directly affect the performance of silver paste in terms of printability, conductivity, weldability and weather resistance.

[0003] Micro-nano silver powder is generally prepared using a liquid-phase reduction method. Chinese Patent Publication No. CN 113290252 A discloses a method for preparing ultrafine silver powder. This involves first adding a polymer protective agent solution to a silver nitrate solution, then adding a strong alkaline solution, and controlling the temperature of the reaction system to prepare reduced silver powder. The resulting silver powder has a small particle size and a high specific surface area, but a low tap density. Chinese Patent Publication No. CN 117680693 A discloses a method for preparing irregular micro-nano silver powder with high surface activity. This method regulates the particle size of the silver powder by introducing a complexing agent during the reaction process. The resulting silver powder has a small particle size and a high specific surface area, but the particle size distribution is less uniform.

[0004] Therefore, it is necessary to provide a micro-nano silver powder with narrow particle size distribution, large specific surface area and high tap density. Summary of the Invention

[0005] In order to solve the problem of how to obtain a micro-nano silver powder with narrow particle size distribution, large specific surface area and high tap density, the present invention provides a highly dispersible micro-nano silver powder and a preparation method and application thereof.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing highly dispersible micro-nano silver powder comprises the following steps:

[0008] S1, adding reducing agent solution I and nucleating agent solution to dispersant solution I to obtain a mixed solution;

[0009] S2. Adding silver nitrate solution I to the mixed solution heated at 30° C.-130° C. to react and obtain a reaction mother solution;

[0010] The mass ratio of dispersant I to silver nitrate I is (0.3-1.5):1; the dispersant I is selected from one of gum arabic, gelatin, guar gum, xanthan gum, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and carboxymethyl cellulose;

[0011] The mass ratio of the nucleating agent to silver nitrate I is (0.001-0.015):1; the nucleating agent is selected from one of trisodium citrate, triethanolamine, sodium bromide, sodium hydroxide, potassium iodide, sodium lauryl sulfate, hexadecyltrimethylammonium bromide, ammonia water, propylene glycol, sodium borohydride, polyvinyl pyrrolidone, and hydrogen peroxide;

[0012] The mass ratio of reducing agent I to silver nitrate I is (75-180):(130-320); the reducing agent is selected from one of diethanolamine, triethanolamine, glucose, hydrazine hydrate, ascorbic acid, glycerol, and propylene glycol;

[0013] S3. Add the reaction mother liquor to the dispersant solution II, and simultaneously add the silver nitrate solution II and the reducing agent solution II to obtain a reaction mixture; the mass ratio of the reaction mother liquor to the silver nitrate II is (0.100-0.150):1; the mass ratio of the dispersant II to the silver nitrate II is (0.3-1.5):1; and the mass ratio of the reducing agent II to the silver nitrate II is (75-180):(130-320);

[0014] The dispersant II is selected from one of gum arabic, gelatin, guar gum, xanthan gum, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and carboxymethyl cellulose;

[0015] The reducing agent II is selected from diethanolamine, triethanolamine, glucose, hydrazine hydrate, ascorbic acid, glycerol, and propylene glycol;

[0016] S4. The reaction mixture obtained in the above step is subjected to solid-liquid separation, and the filter residue is washed with deionized water until the conductivity is ≤10 μs / cm to obtain a wet powder. The wet powder is emulsified, dried, crushed, and passed through a 200-mesh sieve to obtain highly dispersible micro-nano silver powder. The highly dispersible micro-nano silver powder has the following performance parameters: D 50 At 0.3μm-0.5μm, D 90 In the range of 0.5μm-1.0μm, D 100 <2μm, tap density>4.3g / cm 3 , the specific surface area is 1.8m 2 / g-2.3m 2 / g.

[0017] In the present invention:

[0018] In step S1, the release rate of silver ions in the reaction mother solution is controlled by introducing a nucleating agent, so as to provide a sufficient number of uniformly sized crystal nuclei for the subsequent secondary reaction, thereby obtaining silver powder after the secondary reaction.

[0019] In step S1, the dispersant is introduced to improve the dispersibility of the silver powder, narrow the particle size distribution, and thus increase the tap density of the silver powder.

[0020] The reaction of the preparation method of the present invention is carried out in two steps, the first step is to obtain a reaction mother liquid, and the second step is to obtain the final silver powder.

[0021] The present invention also relates to a highly dispersible micro-nano silver powder, which is obtained by using the above-mentioned method for preparing highly dispersible micro-nano silver powder. The highly dispersible micro-nano silver powder has the following performance parameters: 50 At 0.3μm-0.5μm, D 90 In the range of 0.5μm-1.0μm, D 100 <2μm, tap density>4.3g / cm 3 , the specific surface area is 1.8m 2 / g-2.3m 2 / g.

[0022] The present invention also relates to a highly dispersible micro-nano silver powder. The present application provides an application of a highly dispersible micro-nano silver powder in the optoelectronic field, specifically in the optoelectronic field, for the preparation of conductive silver paste for solar cells and electronic components.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The method for preparing highly dispersible micro-nano silver powder of the present invention controls the release rate of silver ions during the entire redox reaction process and the number of silver nuclei formed by introducing a nucleating agent through a secondary reaction, thereby regulating the size of the silver powder particles and increasing the specific surface area.

[0025] 2. The highly dispersible micro-nano silver powder of the present invention improves the dispersibility of the silver powder, narrows the particle size distribution, and thus increases the tap density of the silver powder by introducing a dispersant.

[0026] 3. The method for preparing highly dispersible micro-nano silver powder of the present invention has the characteristics of simple operation, stability and high efficiency. The silver powder obtained has a high yield and is easy to clean, and is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an electron microscope photograph of the highly dispersed micro-nano silver powder prepared in Example 1 of the present invention;

[0028] Figure 2 This is an electron microscope photograph of the highly dispersed micro-nano silver powder prepared in Example 2 of the present invention;

[0029] Figure 3 This is an electron microscope photograph of the highly dispersed micro-nano silver powder prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The present solution is further described below through specific implementation methods.

[0032] Example 1:

[0033] A method for preparing highly dispersible micro-nano silver powder comprises the following steps:

[0034] Raw material preparation:

[0035] Weigh 150 g of analytical grade silver nitrate and dissolve it in 4 L of deionized water to obtain silver nitrate solution I for later use. Weigh 1600 g of analytical grade silver nitrate and dissolve it in 16 L of deionized water to obtain silver nitrate solution II for later use.

[0036] Weigh 110 g of triethanolamine and dissolve it in 1 L of deionized water to obtain reducing agent solution I for later use. Weigh 1200 g of triethanolamine and dissolve it in 16 L of deionized water to obtain reducing agent solution II for later use.

[0037] Weigh 0.15g of trisodium citrate and dissolve it in 50ml of deionized water to obtain a nucleating agent solution for later use;

[0038] 160 g of gum arabic was dissolved in 2 L of deionized water to obtain dispersant solution I for later use. 570 g of gum arabic was dissolved in 16 L of deionized water to obtain dispersant solution II for later use.

[0039] S1. The reducing agent solution I, the nucleating agent solution was added to the dispersant solution I to obtain a mixed solution;

[0040] S2. The mixed solution was transferred to a stirred tank, stirred, heated and maintained at 90 ° C, under stirring at 100 r / min, the silver nitrate solution I was added to the mixed solution in the heated state, and stirring was continued for 15 min after the addition was completed, until the reaction was complete, and the reaction mother liquor was removed for standby;

[0041] S3. Take 2.5L of the reaction mixture was added to a stirred tank containing a dispersant solution II and stirred at a speed of 400r / min, and a silver nitrate solution II and a reducing agent solution II were added to obtain a reaction mixture;

[0042] S4. After standing for 30 minutes, the mixture is discharged into a solid-liquid separator, filtered, and washed with deionized water until the conductivity is below 10 μs / cm. The wet powder is then dried in a forced air drying oven at 65°C for 18 hours. The dried silver powder is crushed and sieved through a 200-mesh screen to obtain highly dispersed micro-nano silver powder.

[0043] The yield of the highly dispersible micro-nano silver powder of this embodiment is 99.90%. The electron microscope image of the prepared silver powder is as follows: Figure 1 As shown in the electron microscope image, it can be seen that the silver powder particle size distribution is uniform and there is no obvious agglomeration, which meets the requirements of highly dispersed micro-nano silver powder.

[0044] Example 2:

[0045] A method for preparing highly dispersible micro-nano silver powder comprises the following steps:

[0046] Prepare raw materials: Weigh 130 g of analytical grade silver nitrate and dissolve it in 3 L of deionized water to obtain silver nitrate solution I. Weigh 1500 g of analytical grade silver nitrate and dissolve it in 16 L of deionized water to obtain silver nitrate solution II.

[0047] Weigh 160 g of glucose and dissolve it in 1.5 L of deionized water to obtain reducing agent solution I for later use. Weigh 1800 g of glucose and dissolve it in 16 L of deionized water to obtain reducing agent solution II for later use.

[0048] Weigh 0.16g of sodium hydroxide and dissolve it in 50ml of deionized water to obtain a nucleating agent solution for later use;

[0049] Weigh 200 g of polyethylene glycol and dissolve it in 2 L of deionized water to obtain dispersant solution I for later use; weigh 800 g of polyethylene glycol and dissolve it in 16 L of deionized water to obtain dispersant solution II for later use.

[0050] S1. The reducing agent solution I, the nucleating agent solution was added to the dispersant solution I to obtain a mixed solution;

[0051] S2. The mixed solution was transferred to a stirred tank, stirred, heated and maintained at 80 ° C, stirred at 250r / min, the silver nitrate solution I was added to the mixed solution in the heated state, and stirring was continued for 30min after the addition was completed, until the reaction was complete, and the reaction mother liquor was removed for standby;

[0052] S3. Take 2.5L of the reaction mixture was added to a stirred tank containing a dispersant solution II and stirred at a speed of 400r / min, and a silver nitrate solution II and a reducing agent solution II were added to obtain a reaction mixture;

[0053] S4. After standing for 20 minutes, the mixture is discharged into a solid-liquid separator, filtered, and washed with deionized water until the conductivity is below 10 μs / cm. The wet powder is then dried in a forced air drying oven at 65°C for 18 hours. The dried silver powder is crushed and sieved through a 200-mesh screen to obtain highly dispersed micro-nano silver powder.

[0054] The yield of the highly dispersible micro-nano silver powder of this embodiment is 99.94%. The electron microscope image of the prepared silver powder is as follows: Figure 2 As shown in the electron microscope image, it can be seen that the silver powder particle size distribution is concentrated, generally distributed in the range of 0.3μm-0.5μm, and there is no adhesion and agglomeration between the particles, which meets the requirements of highly dispersed micro-nano silver powder.

[0055] Example 3:

[0056] A method for preparing highly dispersible micro-nano silver powder comprises the following steps:

[0057] Raw material preparation: Weigh 150 g of analytical grade silver nitrate and dissolve it in 4 L of deionized water to obtain silver nitrate solution I. Weigh 1600 g of analytical grade silver nitrate and dissolve it in 16 L of deionized water to obtain silver nitrate solution II.

[0058] Weigh 60 g of ascorbic acid and dissolve it in 4 L of deionized water to obtain reducing agent solution I. Weigh 640 g of ascorbic acid and dissolve it in 16 L of deionized water to obtain reducing agent solution II.

[0059] Weigh 0.10 g of sodium borohydride and dissolve it in 50 ml of deionized water to obtain a nucleating agent solution for later use;

[0060] Weigh 225 g of polyvinyl pyrrolidone and dissolve it in 2 L of deionized water to obtain a dispersant solution I for later use. Weigh 2400 g of polyvinyl pyrrolidone and dissolve it in 16 L of deionized water to obtain a dispersant solution II for later use.

[0061] S1. The reducing agent solution I, the nucleating agent solution was added to the dispersant solution I to obtain a mixed solution;

[0062] S2. The mixed solution was transferred to a stirred tank, stirred, heated and maintained at 60 ° C, stirred at 250r / min, the silver nitrate solution I was added to the mixed solution in the heated state, and stirring was continued for 15min after the addition was completed, until the reaction was complete, and the reaction mother liquor was removed for standby;

[0063] S3. Take 2.5L of the reaction mixture was added to a stirred tank containing a dispersant solution II and stirred at a speed of 400r / min, and a silver nitrate solution II and a reducing agent solution II were added to obtain a reaction mixture;

[0064] S4. After standing for 30 minutes, the mixture is discharged into a solid-liquid separator, filtered, and washed with deionized water until the conductivity is below 10 μs / cm. The wet powder is then dried in a forced air drying oven at 65°C for 18 hours. The dried silver powder is crushed and sieved through a 200-mesh screen to obtain highly dispersed micro-nano silver powder.

[0065] The yield of the highly dispersible micro-nano silver powder of this embodiment is 99.93%. The electron microscope image of the prepared silver powder is as follows: Figure 3 As shown in the electron microscope image, it can be seen that the silver powder particles are uniform in size and there is no agglomeration between the particles, which meets the requirements of highly dispersed micro-nano silver powder.

[0066] Comparative Example 1:

[0067] A method for preparing micro-nano silver powder is the same as Example 1 except that no nucleating agent is added.

[0068] Comparative Example 2:

[0069] A method for preparing micro-nano silver powder is the same as Example 1 except that no dispersant is added.

[0070] Table 1 Particle size, tap density and specific surface area of ​​the silver powder obtained in the specific embodiment

[0071]

[0072] Results and Discussion

[0073] 1. By comparing Examples 1-3 with Comparative Example 1, it can be seen that the lack of nucleating agent will cause the silver powder particle size to become significantly larger, the distribution is very wide, and the tap density is only 2.67g / cm 3 , does not meet the high compaction requirements.

[0074] 2. By comparing Examples 1-3 with Comparative Example 2, it can be seen that the lack of dispersant will lead to larger silver powder particle size, smaller tap density, and smaller specific surface area.

[0075] 3. It can be seen that the highly dispersible micro-nano silver powder obtained by the preparation method of the highly dispersible micro-nano silver powder of the present invention has the following performance parameters: D 50 At 0.3μm-0.5μm, D 90 In the range of 0.5μm-1.0μm, D 100 <2μm, tap density>4.3g / cm 3 , with a specific surface area of ​​1.8-2.3m 2 / g. The highly dispersible micro-nano silver powder obtained in this application has a narrow particle size distribution, a large specific surface area, and a high tap density, which is conducive to improving its sintering activity and aging resistance. The silver powder prepared in this application is stable in performance and has minimal fluctuation in indicators between batches. The yield of the highly dispersible micro-nano silver powder is 99.90-99.94%.

[0076] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes and substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing highly dispersible micro-nano silver powder, characterized by: The following steps are involved: S1, adding reducing agent solution I and nucleating agent solution to dispersant solution I to obtain a mixed solution; S2. Adding silver nitrate solution I to the mixed solution heated at 30° C.-130° C. to react and obtain a reaction mother solution; The mass ratio of the dispersant I in the dispersant solution I to the silver nitrate I in the silver nitrate solution I is (0.3-1.5):1; The dispersant is selected from one of gum arabic, gelatin, guar gum, xanthan gum, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and carboxymethyl cellulose; The mass ratio of the nucleating agent to silver nitrate I is (0.001-0.015):1; The nucleating agent is selected from one of trisodium citrate, triethanolamine, sodium bromide, sodium hydroxide, potassium iodide, sodium lauryl sulfate, hexadecyltrimethylammonium bromide, ammonia water, propylene glycol, sodium borohydride, polyvinylpyrrolidone, and hydrogen peroxide; The mass ratio of the reducing agent I in the reducing agent solution I to the silver nitrate I in the silver nitrate solution I is (75-180):(130-320); The reducing agent is selected from one of diethanolamine, triethanolamine, glucose, hydrazine hydrate, ascorbic acid, glycerol, and propylene glycol; S3, adding the reaction mother liquor to the dispersant solution II, and simultaneously adding the silver nitrate solution II and the reducing agent solution II to obtain a reaction mixture; The mass ratio of the reaction mother liquor to silver nitrate II is (0.100-0.150):1; The mass ratio of dispersant II in dispersant solution II to silver nitrate II in silver nitrate solution II is (0.3-1.5):1; The mass ratio of reducing agent II to silver nitrate II is (75-180):(130-320); S4. The reaction mixture obtained in the above step is subjected to solid-liquid separation, and the filter residue is washed with deionized water until the conductivity is ≤10 μs / cm to obtain a wet powder. The wet powder is emulsified, dried, crushed, and passed through a 200-mesh sieve to obtain highly dispersible micro-nano silver powder. The highly dispersible micro-nano silver powder has the following performance parameters: D 50 At 0.3μm-0.5μm, D 90 In the range of 0.5μm-1.0μm, D 100 <2μm, tap density>4.3g / cm 3 , the specific surface area is 1.8m 2 / g-2.3m 2 / g.

2. A highly dispersible micro-nano silver powder, characterized by: The highly dispersible micro-nano silver powder prepared by the method of claim 1 has the following performance parameters: 50 At 0.3μm-0.5μm, D 90 In the range of 0.5μm-1.0μm, D 100 <2μm, tap density>4.3g / cm 3 , the specific surface area is 1.8m 2 / g-2.3m 2 / g.

3. The use of a highly dispersible micro-nano silver powder according to claim 2, characterized in that: It is used in the field of optoelectronics.

4. The use of a highly dispersible micro-nano silver powder according to claim 3, characterized in that: The application in the field of optoelectronics is for the preparation of conductive silver paste for solar cells and electronic components.

Images