A method for preparing highly dispersible submicron silver powder
By preparing silver nitrate and reducing agent in organic solvents, adjusting pH value and stirring centrifugal steps, the problems of agglomeration and cleaning of organic matter in submicron silver powder under alkaline conditions are solved, and high dispersion and low-cost silver powder are achieved Preparation enhances the market competitiveness of the product.
Patent Information
- Application Number
- CN202210129413.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-02-11
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2042-02-11
AI Technical Summary
In the preparation of submicron silver powder, the silver powder particles are agglomerated and the content of organic matter under alkaline conditions, which is difficult to clean, affecting dispersion and product quality.
The reaction between silver nitrate and reducing agent is prepared in organic solvents. By adjusting pH value and stirring centrifugation, the formation and cleaning process of silver powder can be controlled to avoid agglomeration and reduce organic content. Use solvents such as anhydrous ethanol and propanol to reduce dispersion. use of agent.
The preparation of high-dispersible submicron silver powder is achieved, which reduces the organic content, improves the monodispersibility of silver powder, significantly reduces production costs, and enhances market competitiveness.
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Figure CN114472917B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of metal powder technology application, and specifically relates to a method for preparing highly dispersible submicron silver powder. Background Art
[0002] Silver, as the most industrially used precious metal, plays a vital role in the national economy. Submicron silver powder is a common industrial raw material. It is not only a functional material, but also a basic material for composite materials. Silver itself has good electrical conductivity, thermal conductivity, and antibacterial properties, so it is widely used in many high-tech fields. Qualified submicron silver powder products are often required to have good dispersibility, narrow distribution, and high purity.
[0003] The main methods for preparing submicron silver powder are liquid phase method, gas phase method and solid phase method. The gas phase method requires large investment, high energy consumption and low yield; the silver powder prepared by the solid phase method has a larger particle size and a wide particle size distribution range: the liquid phase chemical reduction method is currently a common method for preparing silver powder in small batches at low cost.
[0004] The liquid phase chemical reduction method is to prepare submicron silver powder by reducing silver from its salt or complex aqueous solution (currently the most widely used is silver nitrate inorganic solution) in the presence of a protective agent. In order to prepare silver powder with good dispersibility, the amount of organic matter such as dispersant is often very large, which also causes trouble in the later washing of silver powder, and even leads to excessive high-temperature ignition loss, resulting in unqualified products.
[0005] In addition, when preparing submicron silver powder under alkaline conditions, the reaction rate is accelerated due to alkalinity, and the primary crystal nuclei are very small (generally tens of nanometers), and then aggregate and grow to form submicron particles. During the aggregation and growth process, a large amount of organic matter will be mixed in the silver powder particles, resulting in too high an organic content in the final product. After washing. Secondly, due to the small silver powder particles, it is easy to form a strong agglomeration phenomenon between the particles, reducing the dispersibility of the product.
[0006] In order to solve the above problems, the present invention provides a method for preparing highly dispersible submicron silver powder. Summary of the invention
[0007] An object of the present invention is to solve at least one of the above problems or disadvantages and to provide at least one advantage as will be described below.
[0008] Another object of the present invention is to provide a method for preparing highly dispersible submicron silver powder, which solves the problem of difficulty in cleaning organic matter in preparing silver powder under alkaline conditions and improves the monodispersity of the silver powder.
[0009] In order to achieve these purposes and other advantages according to the present invention, the present invention provides a method for preparing highly dispersible submicron silver powder, comprising the following steps:
[0010] Prepare a reducing agent organic solution for later use;
[0011] Prepare an organic solution of silver nitrate for later use;
[0012] The silver nitrate organic solution is added into the reducing agent organic solution for reaction to obtain silver powder.
[0013] Preferably, preparing the reducing agent organic solution comprises:
[0014] Dissolve 5-10 g of reducing agent in a solvent to prepare a reducing agent organic solution with a concentration of 20-40 g / L, and adjust the pH to 9-12.
[0015] Preferably, the reducing agent is one or more of ascorbic acid, aqueous hydrogen peroxide solution, and hydroquinone.
[0016] Preferably, preparing the silver nitrate organic solution comprises:
[0017] Dissolving 15-50 g of silver nitrate solid in a solvent to prepare a silver nitrate organic solution having a concentration of 60-200 g / L;
[0018] Adjust the pH of the silver nitrate organic solution to 9-12.
[0019] Preferably, the solvent is one or more of anhydrous ethanol, propanol, isopropanol, or one or more of the above organic solvents containing deionized water.
[0020] Preferably, adding the silver nitrate organic solution to the reducing agent organic solution to react to obtain the silver powder comprises:
[0021] The silver nitrate organic solution is added to the reducing agent organic solution, stirred for 10-30 minutes, centrifuged, washed, dried, and then ground to obtain silver powder.
[0022] Preferably, the solvent for adjusting pH is one or more of dilute nitric acid, ammonia water, ethanolamine, and sodium hydroxide.
[0023] Beneficial Effects of the Invention
[0024] 1. The present invention provides a method for preparing highly dispersible submicron silver powder, which avoids the problem of silver powder particle agglomeration under alkaline conditions.
[0025] 2. The present invention provides a method for preparing highly dispersible submicron silver powder, which prepares the silver powder under alkaline conditions, and the cleaning of organic matter is simple and effective, thereby effectively reducing the organic matter content in the silver powder.
[0026] 3. The present invention provides a method for preparing highly dispersible submicron silver powder, which improves the monodispersity of silver and has significant economic benefits and market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a schematic flow chart of the method for preparing highly dispersible submicron silver powder of the present invention;
[0028] Figure 2 This is an electron microscope image of the silver powder obtained in Example 1 of the present invention. DETAILED DESCRIPTION
[0029] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.
[0030] It should be understood that terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.
[0031] The present invention provides a method for preparing highly dispersible submicron silver powder, such as Figure 1 As shown, the following steps are included:
[0032] Step 1, preparing a reducing agent organic solution:
[0033] Dissolve 5-10 g of reducing agent in a solvent to prepare a reducing agent organic solution with a concentration of 20-40 g / L, and adjust the pH to 9-12.
[0034] Wherein, the reducing agent is one or more of ascorbic acid, hydrogen peroxide solution, and hydroquinone.
[0035] Wherein, the solvent is one or more of anhydrous ethanol, propanol, isopropanol, or one or more of the above solutions containing deionized water.
[0036] Step 2, prepare silver nitrate organic solution:
[0037] Dissolving 15-50 g of silver nitrate solid in a solvent to prepare a silver nitrate organic solution having a concentration of 60-200 g / L;
[0038] Adjust the pH of the silver nitrate organic solution to 9-12;
[0039] Step 3, adding the silver nitrate organic solution into the reducing agent organic solution to react and obtain silver powder.
[0040] The silver nitrate organic solution is added to the reducing agent organic solution, stirred for 10-30 minutes, centrifuged, washed, dried, and then ground to obtain silver powder.
[0041] The solvent for adjusting pH is one or more of dilute nitric acid, ammonia water, ethanolamine and sodium hydroxide.
[0042] Advantages of ammonia and ethanolamine: If ammonia and ethanolamine are used to adjust the pH, they can complex with Ag ions, slow down the reduction reaction, and make the prepared silver powder morphology closer to a spherical shape, which can avoid the agglomeration of silver powder particles.
[0043] Sodium hydroxide: If sodium hydroxide is used to adjust the pH, it only plays the role of adjusting the pH. Compared with ammonia and ethanolamine, the reaction speed of preparing silver ions is faster.
[0044] The solvent used is one or more of anhydrous ethanol, propanol, isopropanol, or one or more of the above solutions containing deionized water. The beneficial effect is that silver powder with good dispersibility can be prepared without adding a dispersant, and the dispersing effect is better than that of a dispersant.
[0045] The present invention provides the following embodiments:
[0046] Example 1
[0047] The present invention provides a method for preparing highly dispersible submicron silver powder, comprising the following steps:
[0048] Weigh 21g of silver nitrate and dissolve it in 250ml of a mixture of 95% ethanol and deionized water;
[0049] Add a certain amount of ethanolamine to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 10.8, and control the temperature of the solution at 40°C;
[0050] Weigh 9.38 g of hydroquinone and dissolve it in 250 ml of a mixed solution of 95% ethanol and deionized water. Control the temperature of the solution at 40°C.
[0051] The silver nitrate organic solution was added to the hydroquinone solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0052] The silver powder prepared in this example has a D50 of 0.52 μm and a specific surface area of 2300 m 2 / Kg, bulk density 1.82g / ml, loss on ignition at 550℃ is 0.11%.
[0053] Example 2
[0054] The present invention provides a method for preparing highly dispersible submicron silver powder, comprising the following steps:
[0055] Weigh 21g of silver nitrate and dissolve it in 250ml of a mixed solution of 80% ethanol and deionized water;
[0056] Add a certain amount of ethanolamine to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 10.8, and control the temperature of the solution at 40°C;
[0057] Weigh 4.25 g of hydroquinone and dissolve it in 250 ml of a mixed solution of 80% ethanol and deionized water. Control the temperature of the solution at 40°C.
[0058] The silver nitrate organic solution was added to the hydroquinone solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0059] The silver powder prepared in this example has a D50 of 0.66 μm and a specific surface area of 1900 m 2 / Kg, bulk density 1.71g / ml, loss on ignition at 550℃ is 0.15%.
[0060] Example 3
[0061] The present invention provides a method for preparing highly dispersible submicron silver powder, comprising the following steps:
[0062] Weigh 21g of silver nitrate and dissolve it in 250ml of a mixture of 60% ethanol and deionized water;
[0063] Add a certain amount of ethanolamine to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 10.8, and control the temperature of the solution at 40°C;
[0064] Weigh 4.25 g of hydroquinone and dissolve it in 250 ml of a mixed solution of 60% ethanol and deionized water. Control the temperature of the solution at 40°C.
[0065] The silver nitrate organic solution was added to the hydroquinone solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0066] The silver powder prepared in this example has a D50 of 0.79 μm and a specific surface area of 1200 m 2 / Kg, bulk density 1.53g / ml, loss on ignition at 550℃ is 0.18%.
[0067] Example 4
[0068] Weigh 21g of silver nitrate and dissolve it in 250ml of a mixed solution of 85% ethanol and deionized water;
[0069] Add a certain amount of dilute ammonia water to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 12, and control the temperature of the solution at 30°C;
[0070] Weigh 14.50 g / L ascorbic acid and dissolve it in 250 ml of a mixed solution of 85% ethanol and deionized water. Control the temperature of the solution at 30°C.
[0071] The silver nitrate organic solution was added to the L-ascorbic acid solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain the silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0072] The silver powder prepared in this example has a D50 of 0.38 μm and a specific surface area of 2000 m 2 / Kg, bulk density 1.76g / ml, loss on ignition at 550℃ is 0.18%.
[0073] Example 5
[0074] Weigh 21g of silver nitrate and dissolve it in 250ml of a mixture of 55% ethanol and deionized water;
[0075] Add a certain amount of dilute ammonia water to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 10, and control the temperature of the solution at 60°C;
[0076] Weigh 14.50 g / L ascorbic acid and dissolve it in 250 ml of a mixture of 55% ethanol and deionized water. Control the temperature of the solution at 60°C.
[0077] The silver nitrate organic solution was added to the L-ascorbic acid solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain the silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0078] The silver powder prepared in this example has a D50 of 0.81 μm, a specific surface area of 1880 m2 / Kg, a bulk density of 1.65 g / ml, and a ignition loss at 550°C of 0.55%.
[0079] Example 6
[0080] Weigh 21g of silver nitrate and dissolve it in 250ml of a mixture of 25% ethanol and deionized water;
[0081] Add a certain amount of dilute ammonia water to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 9, and control the temperature of the solution at 60°C;
[0082] Weigh 14.50 g / L ascorbic acid and dissolve it in 250 ml of a mixture of 55% ethanol and deionized water. Control the temperature of the solution at 60°C.
[0083] The silver nitrate organic solution was added to the L-ascorbic acid solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain the silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0084] The silver powder prepared in this example has a D50 of 1.57 μm and a specific surface area of 1360 m 2 / Kg, bulk density 1.33g / ml, loss on ignition at 550℃ is 1.2%.
[0085] Example 7
[0086] Weigh 15g of silver nitrate and dissolve it in 250ml of a mixture of 75% propanol and deionized water;
[0087] Add a certain amount of dilute ammonia water to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 10, and control the temperature of the solution at 60°C;
[0088] Measure 40 ml of hydrogen peroxide solution and dissolve it in 360 ml of a mixture of 75% propanol and deionized water. Control the temperature of the solution at 60°C.
[0089] The silver nitrate organic solution was added to the hydrogen peroxide solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0090] The silver powder prepared in this example has a D50 of 3.08 μm and a specific surface area of 650 m 2 / Kg, bulk density 2.24g / ml, loss on ignition at 550℃ is 0.02%.
[0091] Example 8
[0092] Weigh 30g of silver nitrate and dissolve it in 250ml of a mixture of 75% propanol and deionized water;
[0093] Add a certain amount of ethanolamine to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 10, and control the temperature of the solution at 60°C;
[0094] Measure 40 ml of hydrogen peroxide solution and dissolve it in 360 ml of a mixture of 75% propanol and deionized water. Control the temperature of the solution at 60°C.
[0095] The silver nitrate organic solution was added to the hydrogen peroxide solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0096] The silver powder prepared in this example has a D50 of 2.77 μm and a specific surface area of 705 m 2 / Kg, bulk density 2.26g / ml, loss on ignition at 550℃ is 0.02%.
[0097] Example 9
[0098] Weigh 50g of silver nitrate and dissolve it in 250ml of a mixture of 55% isopropanol and deionized water;
[0099] Add a certain amount of dilute ammonia water to the silver nitrate organic solution, adjust the pH of the silver nitrate organic solution to 10, and control the temperature of the solution at 60°C;
[0100] Measure 20 ml of hydrogen peroxide solution and dissolve it in 380 ml of a mixture of 55% isopropyl alcohol and deionized water. Control the temperature of the solution at 60°C.
[0101] The silver nitrate organic solution was added to the hydrogen peroxide solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0102] The silver powder prepared in this example has a D50 of 2.59 μm and a specific surface area of 780 m 2 / Kg, bulk density 2.31g / ml, loss on ignition at 550℃ is 0.02%.
[0103] The present invention also provides a comparative test as follows:
[0104] Comparative test 1 is a comparative test of Example 1, in which silver nitrate is dissolved in an aqueous solution instead of an organic solvent, and the specific steps are as follows:
[0105] Weigh 21g of silver nitrate and dissolve it in 250ml of deionized water;
[0106] Add a certain amount of ethanolamine to the silver nitrate solution, adjust the pH of the silver nitrate solution to 10.8, and control the temperature of the solution at 40°C;
[0107] Weigh 9.38 g of hydroquinone and dissolve it in 250 ml of deionized water. Control the temperature of the solution at 40°C.
[0108] The silver nitrate solution was added to the hydroquinone solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0109] The silver powder prepared in this example has a D50 of 1.98 μm and a specific surface area of 1480 m 2 / kg, bulk density 2.30g / ml, loss on ignition at 550℃ is 1.98%.
[0110] Comparative experiment 2 is a comparative experiment of Example 1, and the specific steps are as follows:
[0111] Weigh 21g of silver nitrate and dissolve it in 250ml of deionized water;
[0112] Weigh 5.5 g of polyvinyl pyrrolidone and dissolve it in a mixed solution of 60% ethanol and deionized water, and add the ethanol solution containing polyvinyl pyrrolidone into the silver nitrate solution;
[0113] Add a certain amount of ethanolamine to the silver nitrate solution, adjust the pH of the silver nitrate solution to 10.8, and control the temperature of the solution at 40°C;
[0114] Weigh 9.38 g of hydroquinone and dissolve it in 250 ml of deionized water. Control the temperature of the solution at 40°C.
[0115] The silver nitrate solution was added to the hydroquinone solution, and the mixture was stirred at a speed of 800 r / min for 20 minutes. The silver powder mixed solution was centrifuged to obtain the impure silver powder. The impure silver powder was first washed with anhydrous ethanol for 3 times, and then washed with hot water for 3 times. The washed impure silver powder was placed in a drying oven and dried for 6 hours to obtain silver powder. The temperature of the hot water was between 60°C and 90°C, and the drying temperature of the drying oven was 70°C.
[0116] The silver powder prepared in this example has a D50 of 1.40 μm and a specific surface area of 1350 m 2 / Kg, bulk density 1.49g / ml, loss on ignition at 550℃ is 1.75%.
[0117] The data of the silver powder prepared in Examples 1 to 9, and Comparative Experiments 1 and 2 are shown in Table 1:
[0118] Table 1
[0119]
[0120]
[0121] In Examples 1 to 6, as the ratio of solvent ethanol to water decreases, the particle size of the silver powder increases, the specific surface area decreases, the bulk density decreases, and the loss on ignition increases in Examples 1-3; as the ratio of solvent ethanol to water increases, the particle size of the silver powder increases, the specific surface area decreases, the bulk density decreases, and the loss on ignition increases in Examples 4-6; after the reducing agent is changed to hydrogen peroxide in Examples 7-9, the protective agent is increased, the particle size of the silver powder decreases, the specific surface area increases, the bulk density increases, and the loss on ignition remains unchanged; in Comparative Experiment 1, after the solvent is replaced with deionized water, the bulk density increases and the loss on ignition also increases; in Comparative Experiment 2, the solvent is changed to deionized water, and the silver powder particles prepared in the aqueous phase are originally larger than the organic phase. After the protective agent (dispersant) is added, although the silver powder particles are reduced, the residual carbon amount is still higher than the residual carbon amount in Examples 1 to 9 using organic solvents.
[0122] The invention provides a method for preparing highly dispersible submicron silver powder, which is simple to operate, significantly reduces the organic matter content in the silver powder, reduces the washing steps, greatly saves the production cost, has market competitiveness, and also improves the dispersibility between silver powder particles, so that it is suitable for industrial production.
[0123] There are other optional embodiments of the present invention, which will not be described in detail here.
[0124] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.
Claims
1. A method for preparing highly dispersible submicron silver powder, characterized in that: The following steps are involved: Weigh 15 g of silver nitrate and dissolve it in 250 ml of a mixture of 75% propanol and deionized water to obtain an organic silver nitrate solution; Adding dilute ammonia water to the silver nitrate organic solution, adjusting the pH to 10, and controlling the temperature at 60° C. to obtain a first solution; 40 ml of hydrogen peroxide solution was measured and dissolved in 360 ml of a mixed solution of 75% propanol and deionized water, and the temperature was controlled at 60° C. to obtain a second solution; The first solution is added to the second solution, and the mixture is stirred at a speed of 800 r / min for 20 minutes, and the mixture is centrifuged to obtain silver powder containing impurities, and the silver powder containing impurities is washed with anhydrous ethanol for 3 times, and then with hot water for 3 times, and the washed silver powder containing impurities is placed in a drying oven and dried for 6 hours to obtain silver powder; The prepared silver powder has a D50 of 3.08 μm and a specific surface area of 650 m 2 / Kg, bulk density 2.24g / ml, loss on ignition at 550℃ is 0.02%.