Silver particles and preparation method and application thereof

Abstract

The invention discloses silver particles and a preparation method and application thereof, and the preparation method comprises the following steps: S1, dispersing a silver source in an alcohol amine solution, and adding a dispersing agent to form a base solution; the molar ratio of silver ions in the silver source to an alcohol amine compound in the alcohol amine solution is 1: (0.05-5); s2, the base solution and an organic amine solution are subjected to a hydrothermal reaction, and the silver particles are prepared; the molar ratio of silver ions in the silver source to the organic amine compound in the organic amine solution is 1: (0.005-0.15). The proportion of the large-particle-size silver particles and the small-particle-size silver particles is regulated and controlled by controlling the dosage of the alcohol amine solution and the organic amine solution, so that gaps of the large-particle-size silver particles are filled with the small-particle-size silver particles, and the tap density of the silver powder is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal powder preparation, and in particular to silver particles and a preparation method and application thereof. Background Art

[0002] Silver paste prepared from quasi-spherical silver powder has the advantages of good fluidity, easy printing, small sintering shrinkage, and dense film, and is widely used in various fields. The most commonly used method for preparing quasi-spherical silver powder is liquid phase chemical reduction, which usually involves mixing a reducing solution and an oxidizing solution, and reducing silver ions to elemental silver through an oxidation-reduction reaction. In this synthesis process, researchers mainly control the oxidation-reduction rate and the growth direction of the silver powder by controlling the type of reducing agent, the amount of dispersant, the pH of the reaction process, the reaction temperature and other conditions to control the particle size and morphology of the silver powder. However, in the actual research process, it was found that this method has limited control over the particle size, especially it is difficult to synthesize small-particle-size and uniformly dispersed silver powder (≤3μm), and the particle size and morphology of the silver powder synthesized based on this method are uneven.

[0003] In the existing synthesis technology, many of them adjust the particle size of silver powder through three processes: preparation of seed crystals, preparation of silver-containing precursor precipitation and oxidation-reduction preparation of nanosilver colloid particles. In addition, different solutions such as oxidizing solution, reducing solution, dispersant solution, complexing agent and precipitating agent need to be prepared in multiple steps. The synthesis process is complicated and time-consuming, which leads to increased production costs. Summary of the invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the object of the present invention is to provide a silver particle and a preparation method and application thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The first aspect of the present invention provides a method for preparing silver particles, comprising the following steps:

[0007] S1: dispersing a silver source in an alcoholamine solution, and adding a dispersant to form a base solution; the molar ratio of silver ions in the silver source to the alcoholamine compound in the alcoholamine solution is 1:0.05-5;

[0008] S2: subjecting the base liquid to a hydrothermal reaction with an organic amine solution to obtain the silver particles; the molar ratio of the silver ions in the silver source to the organic amine compound in the organic amine solution is 1:0.005-0.15.

[0009] In the present invention, the amount of silver particles of different sizes can be adjusted by controlling the amount of different reducing agents used in the preparation process. The silver source reacts with the alcohol amine solution to generate small-diameter silver particles, and the silver source reacts with the organic amine solution to generate large-diameter silver particles. The dispersant is added before the large-diameter silver particles are generated, which is beneficial to improve the dispersion of the small-diameter silver particles, so that they can be effectively filled into the gaps between the large-diameter silver particles during the generation of the large-diameter silver particles. The ratio of large-diameter to small-diameter silver particles in the product can be coordinated with each other, and the tap density after the silver particles are piled up is improved. If the amount of the bottom liquid alcohol amine solution used in the preparation process is too much, the product will agglomerate, and when the amount of organic amine added is too large, the maximum diameter (D100) of the silver particles will increase significantly, which is not conducive to improving the tap density of the silver particles.

[0010] In some embodiments of the present invention, the molar ratio of silver ions in the silver source to the alcoholamine compound in the alcoholamine solution is 1:0.5-5, such as 1:1-4.5, 1:1-4.0, 1:1-3.5, 1:1-3.0.

[0011] In some embodiments of the present invention, the molar ratio of silver ions in the silver source to the organic amine compound in the organic amine solution is 1:0.01-0.15, such as 1:0.02-0.13, 1:0.03-0.12, 1:0.04-0.11, 1:0.05-0.10, 1:0.06-0.09, etc.

[0012] In some embodiments of the present invention, the mass ratio of silver atoms in the silver source to the dispersant is 1:0.01-10, such as 1:0.05-8, 1:0.1-7, 1:0.5-6, 1:1-5, etc.

[0013] In some embodiments of the present invention, the molar concentration of the silver source in the base solution is 0.008-5 mol / L, such as 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L, and 4.5 mol / L.

[0014] In some embodiments of the present invention, the pH of the organic amine solution is 9-14, such as 10-13, 10.5, 11, 11.5, 12, 12.5, etc.

[0015] In some embodiments of the present invention, the pH of the organic amine solution may be adjusted by using a pH adjuster such as at least one of sodium carbonate, sodium hydroxide, ammonia water, monoethanolamine, and triethanolamine.

[0016] In some embodiments of the present invention, the silver source is a soluble silver salt, including at least one of silver nitrate, silver perchlorate, silver acetate, silver oxalate, silver chlorate, silver hexafluorophosphate, silver tetrafluoroborate, silver hexafluoroarsenate, and silver sulfate.

[0017] In some embodiments of the present invention, the alcoholamine compound in the alcoholamine solution is selected from at least one of diethanolamine, methyldiethanolamine, ethanolamine, dimethylethanolamine, diglycolamine, isopropanolamine, triisopropanolamine, oleic acid diethanolamide, stearic acid diethanolamide, lauric acid diethanolamide and octadecyl diethanolamine.

[0018] In some embodiments of the present invention, the dispersant includes at least one of polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, sodium citrate, sodium lauryl sulfate, hexadecyltrimethylammonium bromide, gelatin, methylcellulose, citric acid, Tween 60, propionic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, acrylic acid, oleic acid, linoleic acid, arachidonic acid, and ricinoleic acid.

[0019] In some embodiments of the present invention, the organic amine compound in the organic amine solution is selected from at least one of triethylamine, N-ethyldiisopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, cyclohexylamine, dimethyloctylamine, dimethyldecylamine, tri(3,6-dioxaheptyl)amine and octylamine.

[0020] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 70-240°C, such as 90-210°C, 90-155°C, 100-200°C, etc.; the time of the hydrothermal reaction is 0.5-12h, such as 1-10h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, etc. The hydrothermal reaction can be temperature controlled by methods known in the art, and a common method is to place the hydrothermal reaction kettle in an oven for temperature control; to improve the uniformity of the reaction, the hydrothermal reaction can be carried out under stirring or after sufficient stirring, and the stirring rate can be controlled at 200-500rpm.

[0021] In some embodiments of the present invention, the method for preparing silver particles further comprises purifying the hydrothermal reaction product, wherein the purification comprises washing, drying, etc. As drying conditions, for example, the drying temperature may be 73° C. for 10 hours. Through the drying, a dry powder is obtained.

[0022] The second aspect of the present invention provides silver particles prepared by the method for preparing silver particles.

[0023] In some embodiments of the present invention, the average particle size of the silver particles is 1.00 to 2.20 μm, such as 1.10 to 2.15 μm, as measured by a laser diffraction particle size distribution measuring device.

[0024] In some embodiments of the present invention, the particle size distribution of the silver particles is determined by a laser diffraction particle size distribution measuring device to satisfy the following relationship: D50 is between 0.9 and 1.7 μm, D100 is between 3.5 and 8.5 μm, and Span is between 1.8 and 2.0.

[0025] In some embodiments of the present invention, as measured by field emission scanning electron microscopy (SEM), in the silver particles, the number of silver particles with an average particle size greater than 0.2 μm / the number of silver particles with an average particle size less than 0.2 μm is 0.25 to 0.65.

[0026] In some embodiments of the present invention, the tap density of the silver particles is 6.60 g / m 3 Above, such as 6.60~7.10g / m 3 .

[0027] The third aspect of the present invention provides a conductive silver paste, comprising a conductive phase, a binder phase and a solvent, wherein the conductive phase is the above-mentioned silver particles.

[0028] In some embodiments of the present invention, the adhesive phase is at least one of tributyl citrate and diethylene glycol butyl ether acetate. Any adhesive phase commonly used in the art can be selected.

[0029] In some embodiments of the present invention, the solvent is selected from at least one of DBE and dimethyl silicone oil, and any solvent commonly used in the art can be selected.

[0030] According to a fifth aspect of the present invention, the use of the above-mentioned silver particles or conductive silver paste in the preparation of solar cells or electronic components is proposed.

[0031] In some embodiments of the present invention, the solar cell further comprises panel glass, on which a coating made of the above conductive silver paste is provided. The conductive silver paste of the present invention can be preferably coated on a substrate such as panel glass by a printing process such as a screen.

[0032] In some embodiments of the present invention, the electronic components include at least one of a membrane switch, a flexible printed circuit board, an electromagnetic shield, a potentiometer, or a wireless radio frequency identification system, etc. The conductive silver paste of the present invention has good application prospects in various electronic components.

[0033] The beneficial effects of the present invention are:

[0034] The preparation method of the present invention controls the ratio of large and small silver particles by controlling the amount of the alcohol amine solution and the organic amine solution, controls the morphology of the silver powder such as the particle size distribution, and fills the small-size silver particles into the gaps between the large-size silver particles, thereby improving the tap density of the silver powder. By optimizing the use ratio of the alcohol amine solution and the organic amine solution, the yield and purity of the silver powder can also be improved, and the occurrence of side reactions can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a SEM image of the silver powder obtained in Example 1 of the present invention.

[0036] Figure 2 This is a SEM image of the silver powder ruler obtained in Example 1 of the present invention.

[0037] Figure 3 This is a SEM image of the silver powder obtained in Example 2 of the present invention.

[0038] Figure 4 This is a SEM image of the silver powder ruler obtained in Example 2 of the present invention.

[0039] Figure 5 This is a SEM image of the silver powder obtained in Example 3 of the present invention.

[0040] Figure 6 This is a SEM image of the silver powder ruler obtained in Example 3 of the present invention.

[0041] Figure 7 This is a SEM image of the silver powder obtained in Example 4 of the present invention.

[0042] Figure 8 This is a SEM image of the silver powder ruler obtained in Example 4 of the present invention.

[0043] Fig. 9 This is a SEM image of the silver powder obtained in Comparative Example 1 of the present invention.

[0044] Fig.10 This is a SEM image of the silver powder ruler obtained in Comparative Example 1 of the present invention.

[0045] Fig.11 This is a SEM image of the silver powder obtained in Comparative Example 2 of the present invention.

[0046] Fig.12 This is a SEM image of the silver powder ruler obtained in Comparative Example 2 of the present invention.

[0047] Fig.13 This is a SEM image of the silver powder obtained in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0049] In the following examples or comparative examples, the materials are prepared as follows:

[0050] Preparation of alcohol amine solution: Use dimethylethanolamine with an active ingredient content of 98%;

[0051] Preparation of organic amine solution: Select octylamine with an active ingredient content of 98%;

[0052] Dispersant preparation: Use 98.5% oleic acid.

[0053] Preparation of pH adjuster solution: Sodium hydroxide solution mass fraction 40%.

[0054] Example 1

[0055] This embodiment prepares a silver particle, and the specific process is as follows:

[0056] 2 g of silver carbonate (silver ion molar amount is 0.0145 mol) is added to the inner tank of the hydrothermal reactor, and 2.468 g of dimethylethanolamine (the molar ratio of dimethylethanolamine to Ag is 2.25:1) and 0.1246 g of oleic acid are added thereto successively, and the inner tank is placed on a magnetic stirrer and stirred at 300 rpm to obtain a base liquid;

[0057] Add 0.0084 g of sodium hydroxide solution to 0.152 g of octylamine, and adjust the pH value of the octylamine to 12 to obtain a reducing agent solution;

[0058] Pour the reducing agent solution into the inner container of the hydrothermal reactor and mix it with the base liquid (the molar ratio of octylamine to Ag is 0.0798:1), turn on the magnetic stirring at 300 rpm for 10 minutes, then put the inner container into the hydrothermal reactor and place it in a 105°C oven for 3 hours;

[0059] After the reaction, the hydrothermal kettle was cooled to room temperature (25°C), and deionized water and alcohol were added to the inner tank of the hydrothermal kettle after the reaction in sequence for washing and drying (drying temperature was 55°C, drying time was 2.5h) to obtain silver particles with a silver powder purity of 99.99% and a yield of 78%.

[0060] The obtained silver powder was characterized by scanning electron microscopy (SEM). Figure 1 shown.

[0061] In this embodiment, the silver particles were tested for particle size distribution, with an average particle size of 1.332 μm, a D50 of 1.12 μm, a D100 of 5.3 μm, and a Span of 1.84. At the same time, the tap density was also tested, and the results showed that the tap density of the silver particles was 6.95 g / m 3 .

[0062] Example 2

[0063] This embodiment prepares a silver particle, and the specific process is as follows:

[0064] 2 g of silver carbonate (silver ion molar amount is 0.0145 mol) is added to the inner tank of the hydrothermal reactor, and 4.388 g of dimethylethanolamine (the molar ratio of dimethylethanolamine to Ag is 4:1) and 0.1246 g of oleic acid are added thereto successively, and the inner tank is placed on a magnetic stirrer and stirred at 300 rpm to obtain a base liquid;

[0065] Add 0.0084 g of sodium hydroxide solution to 0.152 g of octylamine, and adjust the pH value of the octylamine to 12 to obtain a reducing agent solution;

[0066] Pour the reducing agent solution into the inner container of the hydrothermal reactor and mix it with the base liquid (the molar ratio of octylamine to Ag is 0.0798:1), turn on the magnetic stirring at 300 rpm for 10 minutes, then put the inner container into the hydrothermal reactor and place it in a 105°C oven for 3 hours;

[0067] After the reaction, the hydrothermal kettle was cooled to room temperature (25°C), and deionized water and alcohol were added to the inner tank of the hydrothermal kettle after the reaction in sequence for washing and drying (drying temperature was 55°C, drying time was 2.5h) to obtain silver particles with a silver powder purity of 99.99% and a yield of 76.60%.

[0068] The obtained silver powder was characterized by scanning electron microscopy (SEM). Figure 2 shown.

[0069] In this embodiment, the silver particles were tested for particle size distribution, with an average particle size of 1.13 μm, a D50 of 0.9962 μm, a D100 of 4.0 μm, and a Span of 1.852. At the same time, the tap density was also tested, and the results showed that the tap density of the silver particles was 6.92 g / m 3 .

[0070] Example 3

[0071] This embodiment prepares a silver particle, and the specific process is as follows:

[0072] 2 g of silver carbonate (silver ion molar amount is 0.0145 mol) is added to the inner tank of the hydrothermal reactor, and 2.468 g of dimethylethanolamine (the molar ratio of dimethylethanolamine to Ag is 2.25:1) and 0.0365 g of oleic acid are added thereto successively, and the inner tank is placed on a magnetic stirrer and stirred at 300 rpm to obtain a base liquid;

[0073] Add 0.0084 g of sodium hydroxide solution to 0.152 g of octylamine, and adjust the pH value of the octylamine to 12 to obtain a reducing agent solution;

[0074] Pour the reducing agent solution into the inner container of the hydrothermal reactor and mix it with the base liquid (the molar ratio of octylamine to Ag is 0.0798:1), turn on the magnetic stirring at 300 rpm for 10 minutes, then put the inner container into the hydrothermal reactor and place it in a 105°C oven for 3 hours;

[0075] After the reaction, the hydrothermal kettle was cooled to room temperature (25°C), and deionized water and alcohol were added to the inner tank of the hydrothermal kettle after the reaction in sequence for washing and drying (drying temperature was 55°C, drying time was 2.5h) to obtain silver particles with a silver powder purity of 99.99% and a yield of 77.80%.

[0076] The obtained silver powder was characterized by scanning electron microscopy (SEM). Figure 3 shown.

[0077] In this embodiment, the silver particles were tested for particle size distribution, with an average particle size of 1.87 μm, a D50 of 1.41 μm, a D100 of 8.0 μm, and a Span of 1.997. At the same time, the tap density was also tested, and the results showed that the tap density of the silver particles was 6.85 g / m 3 .

[0078] Example 4

[0079] This embodiment prepares a silver particle, and the specific process is as follows:

[0080] 2 g of silver carbonate (silver ion molar amount is 0.0145 mol) is added to the inner tank of the hydrothermal reactor, and 2.468 g of dimethylethanolamine (the molar ratio of dimethylethanolamine to Ag is 2.25:1) and 0.1246 g of oleic acid are added thereto successively, and the inner tank is placed on a magnetic stirrer and stirred at 300 rpm to obtain a base liquid;

[0081] Add 0.0084 g of sodium hydroxide solution to 0.152 g of octylamine, and adjust the pH value of the octylamine to 12 to obtain a reducing agent solution;

[0082] Pour the reducing agent solution into the inner tank of the hydrothermal reactor and mix it with the base liquid (the molar ratio of octylamine to Ag is 0.12:1), turn on the magnetic stirring at 300 rpm for 10 minutes, then put the inner tank into the hydrothermal reactor and place it in a 105°C oven for 3 hours;

[0083] After the reaction, the hydrothermal kettle was cooled to room temperature (25°C), and deionized water and alcohol were added to the inner tank of the hydrothermal kettle after the reaction in sequence for washing and drying (drying temperature was 55°C and drying time was 2.5h) to obtain silver particles with a silver powder purity of 99.99% and a yield of 76.8%.

[0084] The obtained silver powder was characterized by scanning electron microscopy (SEM). Figure 4 shown.

[0085] In this embodiment, the silver particles were tested for particle size distribution, with an average particle size of 2.11 μm, a D50 of 1.63 μm, a D100 of 8.0 μm, and a Span of 1.95. At the same time, the tap density was also tested, and the results showed that the tap density of the silver particles was 6.62 g / m 3 .

[0086] Comparative Example 1

[0087] This comparative example prepared a silver particle, which differed from Example 1 in that the molar ratio of dimethylethanolamine to Ag was 8: 1. The purity of the silver powder was 92.40%, and the yield was 72%.

[0088] The obtained silver powder was characterized by scanning electron microscopy (SEM). Figure 5 shown.

[0089] In this embodiment, the silver particles were tested for particle size distribution, with an average particle size of 3.06 μm, a D50 of 2.426 μm, a D100 of 15.0 μm, and a Span of 2.13. At the same time, the tap density was also tested, and the results showed that the tap density of the silver particles was 5.89 g / m 3 .

[0090] It can be seen that too high an amount of the amine solution will cause obvious agglomeration of the product.

[0091] Comparative Example 2

[0092] This comparative example prepared a silver particle, which differed from Example 1 in that the molar ratio of octylamine to Ag was 0.3:1. The purity of the silver powder was 89.60%, and the yield was 68%.

[0093] The obtained silver powder was characterized by scanning electron microscopy (SEM). Figure 6 shown.

[0094] In this embodiment, the silver particles were tested for particle size distribution, with an average particle size of 4.83 μm, a D50 of 3.298 μm, a D100 of 27.0 μm, and a Span of 2.45. At the same time, the tap density was also tested, and the results showed that the tap density of the silver particles was 5.71 g / m 3 .

[0095] It can be seen that excessive use of organic amine solution will lead to a significant increase in the D100 of the drink particles.

[0096] Comparative Example 3

[0097] This comparative example prepared a silver particle, which differed from Example 1 in that the molar ratio of dimethylethanolamine to Ag was 6:1, and the molar ratio of octylamine to Ag was 0.25:1. The purity of the silver powder was 93.30%, and the yield was 69.60%.

[0098] The obtained silver powder was characterized by scanning electron microscopy (SEM). Figure 7 shown.

[0099] In this embodiment, the silver particles were tested for particle size distribution, with an average particle size of 11.23 μm, a D50 of 8.1 μm, a D100 of 35.0 μm, and a Span of 2.81. At the same time, the tap density was also tested, and the results showed that the tap density of the silver particles was 5.32 g / m 3 .

[0100] It can be seen that when the dosage of alcohol amine solution and organic amine solution is too high, the silver powder will be obviously agglomerated and the dispersion will be extremely poor. The average particle size, D50 and D100 of the silver particles will increase significantly.

[0101] Test Case

[0102] The silver particles obtained in the embodiments and comparative examples were statistically analyzed. The statistical method was as follows: 1 um was used as a scale to analyze the silver particles obtained in the embodiments and comparative examples. The statistical method was as follows: 9% to 15% of the area of ​​the silver powder SEM image was selected as the statistical object to ensure that the number of particles selected in each image remained consistent, and the number of silver particles with a particle size of 0.2 μm or more (inclusive) and 0.2 μm or less was counted. The test graph is shown in FIG. Figure 2 , 4 , 6, 8, 10, 12, and the results are shown in Table 1.

[0103] Table 1

[0104]

[0105] Among them, the particle condition of Comparative Example 3 could not be determined due to severe agglomeration.

[0106] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing silver particles, characterized in that: S1: dispersing a silver source in an alcoholamine solution, and adding a dispersant to form a base solution; the molar ratio of silver ions in the silver source to the alcoholamine compound in the alcoholamine solution is 1:0.05-5; S2: subjecting the base liquid to a hydrothermal reaction with an organic amine solution to obtain the silver particles; the molar ratio of the silver ions in the silver source to the organic amine compound in the organic amine solution is 1:0.005-0.

15.

2. The method for preparing silver particles according to claim 1, characterized in that: The pH of the organic amine solution is 9-14.

3. The method for preparing silver particles according to claim 1, characterized in that: The mass ratio of silver atoms in the silver source to the dispersant is 1:0.01-10.

4. The method for preparing silver particles according to claim 1, characterized in that: In the base solution, the molar concentration of the silver source is 0.008-5 mol / L.

5. The method for preparing silver particles according to claim 1, characterized in that: The alcoholamine compound in the alcoholamine solution is selected from at least one of diethanolamine, methyldiethanolamine, ethanolamine, dimethylethanolamine, diglycolamine, isopropanolamine, triisopropanolamine, oleic acid diethanolamide, stearic acid diethanolamide, lauric acid diethanolamide and octadecyl diethanolamine.

6. The method for preparing silver particles according to claim 1, characterized in that: The organic amine compound in the organic amine solution is selected from at least one of triethylamine, N-ethyldiisopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, cyclohexylamine, dimethyloctylamine, dimethyldecylamine, tri(3,6-dioxaheptyl)amine and octylamine.

7. Silver particles obtained by the method for preparing silver particles according to any one of claims 1 to 6.

8. The silver particles according to claim 7, characterized in that: The particle size distribution of the silver particles satisfies the following relationship: D50 is between 0.9 and 1.7 μm, D100 is between 3.5 and 8.5 μm, and Span is between 1.8 and 2.

0.

9. A conductive silver paste comprising a conductive phase, a binder phase and a solvent, wherein the conductive phase is the silver particles according to any one of claims 1 to 6.

10. Use of the silver particles according to any one of claims 1 to 6 or the conductive silver paste according to claim 9 in the preparation of solar cells or electronic components.

Images