Controllable preparation method of micro-sized flaky silver powder
By precisely controlling the morphology of silver powder with bio-based dispersants, regular micro-sized flake-shaped silver powder was prepared, solving the problem of morphology control in existing technologies and realizing the application of micro-sized silver powder with high conductivity and environmental friendliness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGYUAN ENGINEERING COLLEGE
- Filing Date
- 2023-11-20
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies make it difficult to precisely control the morphology of flake silver powder, which limits its widespread application in the field of conductive materials.
Bio-based dispersants were prepared using 5-hydroxymethylfurfural, a bio-based platform compound, as a raw material. By controlling the pH value and the ratio of reducing agent, the morphology of silver powder was precisely controlled, resulting in micro-sized flake silver powder with regular morphology and good dispersibility.
The prepared flake silver powder has a large specific surface area and excellent electrical conductivity, is low in cost, conforms to the concept of green chemistry, and is suitable for new energy fields such as solar panels and electronic materials.
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Figure CN117753981B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of new application technology of bio-based products, specifically relating to a micro-sized flake silver powder and its preparation method. Background Technology
[0002] In the field of new energy conductive materials, silver, a precious metal, boasts the highest conductivity among metals and the lowest cost. Furthermore, silver exhibits excellent oxidation resistance, solderability, and adhesion. Flake-shaped micro-sized silver powder, leveraging the nano-effect, significantly enhances surface activity, catalytic performance, and antibacterial capabilities, showing broad application prospects in many fields. However, the precise control and preparation of the morphology of flake-shaped silver powder remains a key factor limiting its significant development. Based on this, by referencing the patent (CN114656431A) on an α,β-unsaturated ketone compound and its preparation method and application, a class of bio-based dispersants using the bio-based platform compound 5-hydroxymethylfurfural as a raw material was developed. After structure-activity relationship studies, a bio-based dispersant capable of precisely controlling the morphology of silver powder into flake-shaped micro-sized silver powder was obtained. The flake-shaped silver powder prepared using this dispersant exhibits uniform particle size, good dispersibility, and a size that can be precisely controlled to around 3.0 μm. This preparation method is simple, uses environmentally friendly and widely available raw materials, fully aligning with the development concept of "green chemistry." Summary of the Invention
[0003] The purpose of this invention is to propose a bio-based dispersant designed and prepared using the bio-based platform compound 5-hydroxymethylfurfural as a raw material. This dispersant can precisely control the morphology of silver powder to form flake-like micro-sized silver powder during the preparation of silver powder. Flake-like silver powder has a large specific surface area and exhibits superior conductivity compared to other morphologies of silver powder. This is because the contact area of the flake surface is larger than that of other morphologies, resulting in relatively lower resistance, better conductivity, and stable chemical properties. Therefore, flake-like silver powder is most conducive to promoting the innovation and development of metallic conductive materials.
[0004] The micro-sized silver material prepared by this invention has high conductivity and can be used as a conductive additive in the preparation of materials such as solar panels and conductive plates for electronic materials. It can also be used as a high-conductivity material in the field of new energy.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0006] A controllable preparation method for micro-sized flake-shaped silver powder includes the following steps:
[0007] (1) Disperse silver nitrate in deionized water and let it dissolve completely. Add solvent to adjust the pH to obtain mixed solution A;
[0008] (2) Mix the reducing agent and the bio-based dispersant and disperse them in deionized water until they are completely dissolved to obtain mixed solution B. Transfer mixed solution A to the obtained mixed solution B and stir the mixture at room temperature for a period of time to obtain mixed solution C.
[0009] (3) The mixed solution C was allowed to stand, washed and dried to finally obtain micro-sized flake silver powder.
[0010] The bio-based dispersant has the structural formula shown in Formula I:
[0011]
[0012] The linear alkyl group R has 3-7 carbon atoms.
[0013] Furthermore, the concentration of silver nitrate in the mixed solution A in step (1) is 0.1-0.2 mol / L.
[0014] Furthermore, the dissolution in step (1) is performed by rapid dissolution using ultrasound; the solvent added to adjust the pH is nitric acid, and the pH is adjusted to 1-4, preferably pH 2.
[0015] Furthermore, the reducing agent in step (2) is selected from ascorbic acid; the molar ratio of the reducing agent to silver nitrate is 2:1-3:1.
[0016] Furthermore, in step (2), the concentration of the reducing agent in the mixed solution B is 0.2-0.3 mol / L.
[0017] Furthermore, in step (2), the bio-based dispersant is 4 wt% of the mass of silver nitrate.
[0018] Furthermore, the dissolution method in step (2) is to use ultrasound to dissolve it quickly; the stirring is magnetic stirring at a speed of 200 rpm; and the reaction time is 20 min.
[0019] Furthermore, in step (3), the washing solvent used in the washing process is selected from one or two of deionized water and ethanol; the filtration and washing operations are repeated 3 times.
[0020] Furthermore, the drying in step (3) is vacuum drying at a temperature of 60°C for 6 hours.
[0021] The micro-sized flake silver powder prepared by the controllable preparation method described in this invention has a flake shape and a size of 3.0-5.0 μm.
[0022] Compared with existing preparation methods, the advantages of the preparation method of this invention are as follows: First, the obtained flake-shaped micro-sized silver powder has a regular shape, good dispersibility, and low cost; Second, the dispersant raw material used is 5-hydroxymethylfurfural, a bio-based platform compound obtained by hydrolysis of biomass resources, which is green and environmentally friendly and conforms to the concept of "green chemistry"; Third, no additional dispersant is used in the preparation of silver powder; Fourth, the preparation of micro-sized flake-shaped silver powder is precise and controllable. This is mainly because at a low pH value, silver ions in the solution successively nucleate and gradually form aggregates. Due to the adsorption and spatial constraint of different long-chain surface dispersants on the surface of silver aggregates, the crystal nuclei can be coated, thereby controlling the growth of the crystal nuclei. When R < 3, the constraint on the crystal nucleus is weak, and the nucleus will grow freely and continuously aggregate to form spherical silver particles. When R > 7, the coating ability of the crystal nucleus is strong enough to coat the silver aggregate and prevent it from growing further, thus forming spherical silver particles. When 3 < R < 7, the dispersant can selectively allow the {111} crystal face to grow and inhibit other crystal faces, gradually forming plate-like silver powder particles. At the same time, the increase in the number of silver nuclei will limit the growth of the crystal nuclei, resulting in a reduction in the size of the silver particles, which can eventually be controlled at around 3.0-5.0 μm. Attached Figure Description
[0023] Figure 1 These are transmission electron microscope (SEM) images of the micro-sized silver particles obtained in Example 3 of this invention;
[0024] Figure 2 These are transmission electron microscope (SEM) images of the micro-sized silver particles obtained in Example 6 of this invention;
[0025] Figure 3 These are transmission electron microscope (SEM) images of the micro-sized silver particles obtained in Example 9 of this invention;
[0026] Figure 4 These are transmission electron microscope (SEM) images of the micro-sized silver particles obtained in Example 12 of this invention. Detailed Implementation
[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0028] The bio-based dispersant involved in this application has the structural formula shown in Formula I:
[0029]
[0030] The linear alkyl group R has 3-7 carbon atoms.
[0031] The preparation method of the bio-based dispersant includes:
[0032] (1) Compound i and compound ii were mixed and condensed in the presence of an alkaline substance and an alcohol solvent to obtain long-chain compound iii;
[0033] Compound i is selected from compounds having the structural formula shown in Formula III;
[0034]
[0035] Compound ii is selected from compounds having the structural formula shown in Formula IV;
[0036]
[0037] The compound iii is selected from compounds having the structural formula shown in formula V;
[0038]
[0039] The straight-chain alkyl group R has 3-7 carbon atoms.
[0040] (2) The long-chain condensation compound obtained in step (1) is mixed with pyridine and pyridine sulfur trioxide complex and stirred at room temperature for 2 hours to obtain the target bio-based dispersant shown in Formula I.
[0041] Furthermore, the equivalent ratio of compound i and compound ii in step (1) is 1:1.2-1:3, preferably 1:1.2.
[0042] Furthermore, the alkaline substance in step (1) is an aqueous solution of sodium hydroxide, and the molar concentration of the aqueous solution of sodium hydroxide is 0.5-2 mol / L; preferably 0.5 mol / L.
[0043] Furthermore, in step (1), the molar ratio of compound i to the basic substance is 1:2.
[0044] Furthermore, the solvent is one of methanol and ethanol; methanol is preferred.
[0045] Furthermore, the reaction temperature in step (1) is room temperature, and the reaction time is 30 min.
[0046] Furthermore, the solvent in step (2) is selected from pyridine, wherein the ratio of the long-chain condensation compound iii obtained in step (1) to pyridine is 25 mg / ml.
[0047] Furthermore, in step (2), the molar ratio of the long-chain condensation compound iii to pyridine sulfur trioxide is 1:1.2-1:3.
[0048] Example 1: Preparation of long-chain condensation products
[0049] Where R = 3.
[0050] Synthesis steps: At room temperature, 0.5 mol / L sodium hydroxide (1.584 mL, 2 equivalents) was added to a methanol (2 mL) mixture of 5-hydroxymethylfurfural (50 mg, 1 equivalent) and 2-pentanone (40.99 mg, 1.2 equivalents), and the mixture was stirred at room temperature for 30 minutes. After the 5-hydroxymethylfurfural reactant disappeared, the reaction system was washed and extracted three times with ethyl acetate and saturated brine. The organic phase was collected, and the aqueous phase was extracted twice with ethyl acetate. The organic phases were combined, dried with anhydrous magnesium sulfate or anhydrous sodium sulfate, filtered to remove the drying agent, and the organic phase was concentrated to obtain the purified long-chain condensation product.
[0051] Example 2: Preparation of Bio-based Dispersants
[0052] Synthesis steps: At room temperature, 2 mL of pyridine was added to the long-chain condensation product (50 mg, 1 equivalent) obtained in Example 1 to prepare a mixed solution. Pyridine sulfur trioxide (45.1 mg, 1.2 equivalent) was then added, and the mixture was stirred for 2 hours. After the long-chain condensation product obtained in Example 1 disappeared, a saturated sodium bicarbonate aqueous solution was added dropwise to quench the reaction. The reaction solution was then concentrated to obtain a purplish-black liquid, which was the target product.
[0053] Example 3
[0054] The preparation steps of the micro-sized silver powder in this embodiment are as follows:
[0055] Step 1: Disperse 0.85g of silver nitrate in 50mL of deionized water and let it dissolve completely. Add 1mol / L dilute nitric acid solution to adjust the pH of the silver nitrate solution to 2 to obtain mixed solution A;
[0056] Step 2: Add 0.0425g of the bio-based dispersant obtained in Example 2 and 0.528g of ascorbic acid to 10mL of water to prepare a mixed solution and make it completely dissolved to obtain mixed solution B. Transfer mixed solution A to the obtained mixed solution B and stir at room temperature for 20 minutes to obtain mixed solution C.
[0057] Step 3: Let the mixed solution C after the reaction stand, pour the supernatant into the waste liquid bucket, repeat the above operation, wash 3 times with deionized water, then wash 3 times with anhydrous ethanol, and dry in a vacuum oven at 60 degrees Celsius for 6 hours to finally obtain micro-sized flake silver powder. Figure 1 ).
[0058] Example 4: Preparation of long-chain condensation products
[0059] Where R = 7.
[0060] Synthesis steps: At room temperature, 0.5 mol / L sodium hydroxide (1.584 mL, 2 equivalents) was added to a mixed solution of 5-hydroxymethylfurfural (50 mg, 1 equivalent) and 2-nonanone (67.67 mg, 1.2 equivalents) in methanol (2 mL), and the mixture was stirred at room temperature for 30 minutes. After the 5-hydroxymethylfurfural reactant disappeared, the reaction system was washed and extracted three times with ethyl acetate and saturated brine. The organic phase was collected, and the aqueous phase was extracted twice with ethyl acetate. The organic phases were combined, dried with anhydrous magnesium sulfate or anhydrous sodium sulfate, filtered to remove the drying agent, and the organic phase was concentrated to obtain the purified long-chain condensation product.
[0061] Example 5: Preparation of Bio-based Dispersants
[0062] Synthesis steps: At room temperature, 2 mL of pyridine was added to the long-chain condensation product (50 mg, 1 equivalent) obtained in Example 4 to prepare a mixed solution. Pyridine sulfur trioxide (34.99 mg, 1.2 equivalent) was then added, and the mixture was stirred for 2 hours. After the long-chain condensation product obtained in Example 4 disappeared, a saturated sodium bicarbonate aqueous solution was added dropwise to quench the reaction. The reaction solution was then concentrated to obtain a purplish-black liquid as the target product.
[0063] Example 6 The preparation steps of the micro-sized silver powder in this example are as follows:
[0064] Step 1: Disperse 0.85g of silver nitrate in 50mL of deionized water and let it dissolve completely. Add 1mol / L dilute nitric acid solution to adjust the pH of the silver nitrate solution to 2 to obtain mixed solution A;
[0065] Step 2: Add 0.0425g of the bio-based dispersant obtained in Example 5 and 0.352g of ascorbic acid to 10mL of water to prepare a mixed solution and make it completely dissolved to obtain mixed solution B. Transfer mixed solution A to the obtained mixed solution B and stir at room temperature for 20 minutes to obtain mixed solution C.
[0066] Step 3: Let the mixed solution C after the reaction stand, pour the supernatant into the waste liquid bucket, repeat the above operation, wash 3 times with deionized water, then wash 3 times with anhydrous ethanol, and dry in a vacuum oven at 60 degrees Celsius for 6 hours to finally obtain micro-sized flake silver powder. Figure 2 ).
[0067] Example 7: Preparation of long-chain condensation products
[0068] Where R = 11.
[0069] Synthesis steps: At room temperature, 2 mol / L sodium hydroxide (0.793 mL, 2 equivalents) was added to a methanol (4 mL) mixture of 5-hydroxymethylfurfural (100 mg, 1 equivalent) and 2-tetridetone (235.64 mg, 3 equivalents), and the mixture was stirred at room temperature for 30 minutes. After the 5-hydroxymethylfurfural reactant disappeared, the reaction system was washed and extracted three times with ethyl acetate and saturated brine. The organic phase was collected, and the aqueous phase was extracted twice with ethyl acetate. The organic phases were combined, dried with anhydrous magnesium sulfate or anhydrous sodium sulfate, filtered to remove the drying agent, and the organic phase was concentrated to obtain the purified long-chain condensation product.
[0070] Example 8: Preparation of Bio-based Dispersants
[0071] Synthesis steps: At room temperature, 2 mL of pyridine was added to the long-chain condensation product (54 mg, 1 equivalent) obtained in Example 7 to prepare a mixed solution. Pyridine sulfur trioxide (84.2 mg, 3 equivalents) was then added to the solution, followed by stirring for 2 hours. After the long-chain condensation product obtained in Example 7 disappeared, a saturated sodium bicarbonate aqueous solution was added dropwise to quench the reaction. The reaction solution was then concentrated to obtain a purplish-black liquid as the target product.
[0072] Example 9
[0073] The preparation steps of the micro-sized silver powder in this embodiment are as follows:
[0074] Step 1: Disperse 0.85g of silver nitrate in 50mL of deionized water and let it dissolve completely. Add 1mol / L dilute nitric acid solution to adjust the pH of the silver nitrate solution to 2 to obtain mixed solution A;
[0075] Step 2: Add 0.0425g of the bio-based dispersant obtained in Example 8 and 0.52g of ascorbic acid to 50mL of water to prepare a mixed solution and make it completely dissolved to obtain mixed solution B. Transfer mixed solution A to the obtained mixed solution B and stir at room temperature for 20 minutes to obtain mixed solution C.
[0076] Step 3: Let the mixed solution C after the reaction stand, pour the supernatant into the waste liquid bucket, repeat the above operation, wash 3 times with deionized water, then wash 3 times with anhydrous ethanol, and dry in a vacuum oven at 60 degrees Celsius for 6 hours to finally obtain micro-sized spherical silver powder. Figure 3 ).
[0077] Example 10 Preparation of long-chain condensation products
[0078] Where R = 1.
[0079] Synthesis steps: At room temperature, 2 mol / L sodium hydroxide (1 mL, 2 equivalents) was added to a mixed solution of 5-hydroxymethylfurfural (126 mg, 1 equivalent), acetone (174.24 mg, 3 equivalents) and methanol (5 mL), and the mixture was stirred at room temperature for 30 minutes. After the 5-hydroxymethylfurfural reactant disappeared, the reaction system was washed and extracted three times with ethyl acetate and saturated brine. The organic phase was collected, and the aqueous phase was extracted twice with ethyl acetate. The organic phases were combined, dried with anhydrous magnesium sulfate or anhydrous sodium sulfate, filtered to remove the drying agent, and the organic phase was concentrated to obtain the purified long-chain condensation product.
[0080] Example 11 Preparation of Bio-based Dispersants
[0081] Synthesis steps: At room temperature, 6 mL of pyridine was added to the long-chain condensation product (155 mg, 1 equivalent) obtained in Example 10 to prepare a mixed solution. Pyridine sulfur trioxide (445.36 mg, 3 equivalents) was then added, and the mixture was stirred for 2 hours. After the long-chain condensation product obtained in Example 10 disappeared, a saturated sodium bicarbonate aqueous solution was added dropwise to quench the reaction. The reaction solution was then concentrated to obtain a purplish-black liquid as the target product.
[0082] Example 12
[0083] The preparation steps of the micro-sized silver powder in this embodiment are as follows:
[0084] Step 1: Disperse 0.85g of silver nitrate in 50mL of deionized water and let it dissolve completely. Add 1mol / L dilute nitric acid solution to adjust the pH of the silver nitrate solution to 4 to obtain mixed solution A;
[0085] Step 2: Add 0.0425g of the bio-based dispersant obtained in Example 11 and 0.528g of ascorbic acid to 10mL of water to prepare a mixed solution and make it completely dissolved to obtain mixed solution B. Transfer mixed solution A to the obtained mixed solution B and stir at room temperature for 20 minutes to obtain mixed solution C.
[0086] Step 3: Let the mixed solution C after the reaction stand, pour the supernatant into the waste liquid bucket, repeat the above operation, wash 3 times with deionized water, then wash 3 times with anhydrous ethanol, and dry in a vacuum oven at 60 degrees Celsius for 6 hours to finally obtain micro-sized spherical silver powder. Figure 4 ).
[0087] The characterization results from the above embodiments show that when the number of carbon atoms in the straight-chain alkyl group R is between 3 and 7, the surface dispersant can precisely control the formation of flake-shaped silver powder. When R < 3, electron microscopy characterization shows that the surface dispersant can control the formation of spherical silver powder instead of flake-shaped powder; when R > 7, experimental electron microscopy characterization shows that the surface dispersant controls the formation of spherical micro-sized silver powder instead of flake-shaped micro-sized silver powder. Therefore, in summary, when R is between 3 and 7, the surface dispersant can precisely control the morphology of the silver powder to be flake-shaped.
[0088] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A controllable preparation method for micro-sized flake-shaped silver powder, characterized in that, Includes the following steps: (1) Disperse silver nitrate in deionized water and let it dissolve completely. Add solvent to adjust the pH to obtain mixed solution A; (2) Mix the reducing agent and the bio-based dispersant and disperse them in deionized water until they are completely dissolved to obtain mixed solution B. Transfer mixed solution A to the obtained mixed solution B and stir the mixture at room temperature for a period of time to obtain mixed solution C. (3) The mixed solution C was allowed to stand, washed and dried to finally obtain micro-sized flake silver powder; The bio-based dispersant has the structural formula shown in Formula I: The linear alkyl group R has 3-7 carbon atoms.
2. The controllable preparation method of micro-sized flake silver powder according to claim 1, characterized in that, The concentration of silver nitrate in the mixed solution A in step (1) is 0.1-0.2 mol / L.
3. The controllable preparation method of micro-sized flake silver powder according to claim 1, characterized in that, The dissolution in step (1) is achieved by using ultrasound for rapid dissolution; the solvent added to adjust the pH is nitric acid, and the pH is adjusted to 1-4.
4. The controllable preparation method of micro-sized flake silver powder according to claim 1, characterized in that, The reducing agent in step (2) is selected from ascorbic acid; the molar ratio of the reducing agent to silver nitrate is 2:1-3:
1.
5. The controllable preparation method of micro-sized flake silver powder according to claim 1, characterized in that, In step (2), the concentration of the reducing agent in the mixed solution B is 0.2-0.3 mol / L.
6. The controllable preparation method of micro-sized flake silver powder according to claim 1, characterized in that, In step (2), the bio-based dispersant is 4 wt% of the mass of silver nitrate.
7. The controllable preparation method of micro-sized flake silver powder according to claim 1, characterized in that, The dissolution method in step (2) is to use ultrasound to dissolve it quickly; the stirring is magnetic stirring at a speed of 200 rpm; and the reaction time is 20 min.
8. The controllable preparation method of micro-sized flake silver powder according to claim 1, characterized in that, In step (3), the washing solvent used in the washing process is selected from one or two of deionized water and ethanol; the filtration and washing operations are repeated 3 times.
9. The controllable preparation method of micro-sized flake silver powder according to claim 1, characterized in that, The drying in step (3) is vacuum drying at a temperature of 60°C for 6 hours.
10. The micro-sized flake silver powder prepared by the controllable preparation method according to any one of claims 1-9, characterized in that, The micro-sized flake silver powder is flake-shaped with a size of 3.0-5.0 μm.