Method for preparing low-apparent-density flaky silver powder through turbo type sand mill

Abstract

The invention discloses a method for preparing low-apparent-density flaky silver powder through a turbo type sand mill, and relates to the technical field of flaky silver powder. The method comprises the following steps: preparing an anti-settling agent solution; adding the anti-settling agent solution into absolute ethyl alcohol, and stirring to obtain an anti-settling agent-ethyl alcohol dispersion liquid; adding spherical silver powder into the anti-settling agent-ethanol dispersion liquid, and stirring to obtain a spherical silver powder-ethanol dispersion liquid subjected to anti-settling pretreatment; adding a dispersing agent into the spherical silver powder-ethanol dispersion liquid subjected to anti-settling pretreatment, and stirring to obtain a to-be-ground material; and a turbo type sand mill is adopted for grinding the to-be-ground material to obtain flake silver powder-ethanol dispersion liquid, then the flake silver powder-ethanol dispersion liquid is dried and screened, and the flake silver powder is obtained. The flaky silver powder prepared through the method has the advantages of being low in apparent density, good in oxidation resistance and good in matching performance with a silver paste organic system.

Description

Technical Field

[0001] The invention belongs to the technical field of flaky silver powder, and in particular relates to a method for preparing flaky silver powder with low bulk density using a turbine sand mill. Background Art

[0002] When flaky silver powder is used as a conductive filler to form a conductive path, it has a relatively low resistance because its particles are in surface contact or line contact, the contact surface is larger, and the silver flake structure forms repeated superposition of upper and lower layers to form a dense conductive circuit. At the same time, the specific surface area of ​​flaky silver powder is larger than that of spherical silver powder, and the surface activation energy is lower than that of spherical or quasi-spherical silver powder, so its oxidation tendency is lower. Flaky silver powder can greatly improve the reliability of electronic components because of its wide deflection range and anti-fracture and elongation characteristics. The silver paste coating made of flaky silver powder has a larger area, so it can maintain good conductivity while reducing the silver content of the silver paste and the thickness of the coating.

[0003] Flake silver powder with a larger diameter-to-thickness ratio often exhibits a lower bulk density, a larger number of silver powder particles per unit volume, and excellent conductivity at a lower silver content. The printed coating is also thinner, which not only effectively reduces the amount of silver used, but also effectively increases the volatilization rate of the silver paste solvent during low-temperature curing, which can meet the needs of quick-drying processes. After curing, the low-temperature silver paste prepared with silver powder with low bulk density has a dense conductive network and good conductive properties, while spherical silver powder with a large bulk density has better conductivity after sintering.

[0004] The mainstream preparation methods of flaky silver powder include mechanical ball milling, chemical reduction, photoinduction, etc. Among them, mechanical ball milling is the most widely used. This method usually uses AgNO3 or Ag2O as the silver source, and uses a chemical precipitation method to reduce it to spherical silver particles of different particle sizes using a reducing agent under the protection of an additive or dispersant. Then, by controlling the ball-to-material ratio, ball milling aid, ball milling speed, ball milling time and other parameters, the spherical silver particles are ball milled by mechanical ball milling to obtain flaky silver powder. The ball milling process is actually a "beating and smashing" effect exerted on the spherical silver powder below the tank body by the movement of the grinding ball in the tank body and when it falls from the highest point of the tank body, the spherical silver powder is deformed into flaky silver powder.

[0005] The most commonly used mechanical ball mill is the drum ball mill, which has low ball milling efficiency and long grinding time. The sand mill is a high-speed stirring ball mill newly developed from the mechanical ball mill. Compared with the traditional ball mill, the sand mill has stronger shear force and impact force, and the grinding efficiency is increased by 2-3 times.

[0006] However, how to ensure that the material circulates smoothly and is evenly ground in the turbine sand mill to obtain flaky silver powder with low bulk density is an urgent problem to be solved. Summary of the invention

[0007] In order to solve the above technical problems, the present invention proposes a method for preparing low bulk density flaky silver powder by a turbine sand mill. By controlling the solid-liquid ratio of the wet abrasive, a spherical silver powder-ethanol dispersion with good fluidity and uniform dispersion is obtained as a slurry, which can not only meet the smooth circulation of materials under the action of the pneumatic diaphragm pump of the turbine sand mill, but also improve the grinding efficiency. In addition, pretreatment of the low-solid content wet abrasive with an anti-settling agent and a silane coupling agent can effectively prevent settling, ensure that the spherical silver powder particles are evenly ground during the cyclic grinding process, make the degree of flaking more uniform, and thus reduce the bulk density of the flaky silver powder.

[0008] The present invention provides a method for preparing low bulk density flaky silver powder using a turbine sand mill, the method comprising the following steps:

[0009] Step S1, mixing an anti-settling agent and a silane coupling agent to obtain an anti-settling agent solution;

[0010] Step S2, adding the anti-precipitation agent solution into anhydrous ethanol and stirring at a first speed for a first preset time to obtain an anti-precipitation agent-ethanol dispersion;

[0011] Step S3, adding the spherical silver powder into the anti-precipitation agent-ethanol dispersion and stirring at a second speed for a second preset time to obtain the spherical silver powder-ethanol dispersion after anti-precipitation pretreatment;

[0012] Step S4, adding a dispersant to the spherical silver powder-ethanol dispersion after the anti-precipitation pretreatment and stirring at a third speed for a third preset time to obtain a material to be ground;

[0013] Step S5, grinding the material to be ground by a turbine sand mill to obtain a flaky silver powder-ethanol dispersion, and then drying and sieving the flaky silver powder-ethanol dispersion to obtain flaky silver powder;

[0014] Among them, the mass of the anti-settling agent is 0.2%-1% of the mass of the spherical silver powder, the mass ratio of the anti-settling agent to the silane coupling agent is 1:10 to 1:2, the mass ratio of the spherical silver powder to anhydrous ethanol is 1:4 to 2:3, and the mass of the dispersant is 0.05%-0.15% of the mass of the spherical silver powder.

[0015] According to the method for preparing low bulk density flaky silver powder by a turbine sand mill of the present invention, in the step S1, the anti-settling agent is one or more of fumed silica, hydrogenated castor oil, and polyamide wax.

[0016] According to the method for preparing low bulk density flaky silver powder by a turbine sand mill of the present invention, in the step S1, the silane coupling agent is one or more of KH-550, KH-560, and KH-570.

[0017] According to the method for preparing low bulk density flaky silver powder by a turbine sand mill of the present invention, in the step S2, the first rotation speed is 800-1200 rpm, and the first preset time is 10-20 min.

[0018] According to the method for preparing low bulk density flaky silver powder by a turbine sand mill of the present invention, in step S3, the particle size of the spherical silver powder is 0.5-1.5 μm, and the purity is >99.99%.

[0019] According to the method for preparing low bulk density flaky silver powder by a turbine sand mill of the present invention, in the step S3, the second rotation speed is 500-1000 rpm, and the second preset time is 10-20 min.

[0020] According to the method for preparing low bulk density flaky silver powder with a turbine sand mill of the present invention, in step S4, the dispersant is one or more of oleic acid, stearic acid, hexadecanoic acid, tetradecanol, and monoglyceride.

[0021] According to the method for preparing low bulk density flaky silver powder by a turbine sand mill of the present invention, in the step S4, the third rotation speed is 500-1000 rpm, and the third preset time is 10-20 min.

[0022] According to the method for preparing low bulk density flaky silver powder by a turbine sand mill of the present invention, in the step S5, the grinding speed is 1000-3000 rpm, and the grinding time is 1-3 hours.

[0023] According to the method for preparing low bulk density flaky silver powder by a turbine sand mill of the present invention, in the step S5, the grinding beads used for grinding are zirconia beads with a diameter of 1 mm.

[0024] The solution proposed by the present invention has the following technical effects:

[0025] The present invention controls the solid-liquid ratio of the wet abrasive to obtain a spherical silver powder-ethanol dispersion with good fluidity and uniform dispersion as a slurry, which can not only meet the smooth circulation of materials under the action of the pneumatic diaphragm pump of the turbine sand mill, but also improve the grinding efficiency. In addition, the pretreatment of the low-solid content wet abrasive with an anti-settling agent and a silane coupling agent can effectively prevent settling, ensure that the spherical silver powder particles are uniformly ground during the cyclic grinding process, make the flaking degree more uniform, and thus reduce the loose density of the flaky silver powder.

[0026] In addition, the turbine sand mill used in the present invention greatly improves the grinding efficiency compared with the traditional drum ball mill, and the flaking process is fast, and the grinding time is controlled within 1-3 hours; on the other hand, compared with the pin-type sand mill, the material can be ground more gently and finely in the grinding chamber, and the rotation of the turbine drives the grinding medium to produce swirl and axial movement, generating uniform and strong shear force, allowing the material to flow in the annular gap and be better dispersed, and the loss of the grinding medium is lower.

[0027] In addition, the flaky silver powder prepared by the method of the present invention has the characteristics of low bulk density, good oxidation resistance and good matching with the organic system of silver paste. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The present invention is a schematic flow chart of a method for preparing low bulk density flaky silver powder using a turbine sand mill in one embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] This embodiment provides a method for preparing low bulk density flaky silver powder using a turbine sand mill. Figure 1 The method comprises the following steps:

[0032] Step S1, mixing an anti-settling agent and a silane coupling agent to obtain an anti-settling agent solution.

[0033] Step S2, adding the anti-precipitation agent solution into anhydrous ethanol and stirring at a first speed for a first preset time to obtain an anti-precipitation agent-ethanol dispersion.

[0034] Step S3, adding the spherical silver powder into the anti-precipitation agent-ethanol dispersion and stirring at a second speed for a second preset time to obtain the spherical silver powder-ethanol dispersion after anti-precipitation pretreatment.

[0035] Step S4, adding a dispersant to the spherical silver powder-ethanol dispersion after the anti-precipitation pretreatment and stirring at a third speed for a third preset time to obtain a material to be ground.

[0036] Step S5, grinding the material to be ground with a turbine sand mill to obtain a flaky silver powder-ethanol dispersion, and then drying and sieving the flaky silver powder-ethanol dispersion to obtain flaky silver powder.

[0037] Among them, the mass of the anti-settling agent is 0.2%-1% of the mass of the spherical silver powder, the mass ratio of the anti-settling agent to the silane coupling agent is 1:10 to 1:2, the mass ratio of the spherical silver powder to anhydrous ethanol is 1:4 to 2:3, and the mass of the dispersant is 0.05%-0.15% of the mass of the spherical silver powder.

[0038] Preferably, the mass of the anti-settling agent is 0.5%-0.7% of the mass of the spherical silver powder, the mass ratio of the anti-settling agent to the silane coupling agent is 1:8 to 1:5, the mass ratio of the spherical silver powder to anhydrous ethanol is 1:3 to 1:2, and the mass of the dispersant is 0.09%-0.11% of the mass of the spherical silver powder.

[0039] Further preferably, the mass of the anti-settling agent is 0.5% of the mass of the spherical silver powder, the mass ratio of the anti-settling agent to the silane coupling agent is 1:5, the mass ratio of the spherical silver powder to anhydrous ethanol is 1:2, and the mass of the dispersant is 0.1% of the mass of the spherical silver powder.

[0040] In this embodiment, by controlling the solid-liquid ratio of the wet abrasive, a spherical silver powder-ethanol dispersion with good fluidity and uniform dispersion is obtained as a slurry, which can not only meet the smooth circulation of materials under the action of the pneumatic diaphragm pump of the turbine sand mill, but also improve the grinding efficiency.

[0041] It should be noted that the order of adding the raw materials in this embodiment is irreplaceable, and the spherical silver powder, anti-settling agent, silane coupling agent, anhydrous ethanol and dispersant cannot be mixed simultaneously, for the following reasons:

[0042] On the one hand, by pre-mixing the anti-settling agent and the silane coupling agent and then mixing them with ethanol to prepare a dispersion to pretreat the low-solid content wet abrasive (spherical silver powder), it can effectively prevent settling and form a suspended solution for the spherical silver powder, ensuring that the spherical silver powder particles are evenly ground during the cyclic grinding process, making the degree of flaking more uniform, and thereby reducing the loose density of the flaky silver powder.

[0043] On the other hand, the silane coupling agent can modify the anti-settling agent, thereby improving the oxidation resistance of the flaky silver powder.

[0044] On the other hand, when the spherical silver powder, the anti-settling agent, the silane coupling agent, the anhydrous ethanol and the dispersant are directly mixed simultaneously, the anti-settling agent cannot be completely dissolved and evenly dispersed.

[0045] In addition, the turbine sand mill used in this embodiment greatly improves the grinding efficiency compared with the traditional drum ball mill, the flaking process is fast, and the grinding time is short; on the other hand, compared with the pin-type sand mill, the material can be ground more gently and finely in the grinding chamber. The rotation of the turbine drives the grinding medium to produce swirl and axial movement, generating uniform and strong shear force, allowing the material to flow in the annular gap and be better dispersed, and the loss of the grinding medium is lower.

[0046] In step S1, an anti-precipitation agent and a silane coupling agent are mixed to obtain an anti-precipitation agent solution.

[0047] In some embodiments, in step S1, the anti-settling agent is one or more of fumed silica, hydrogenated castor oil, and polyamide wax.

[0048] In some embodiments, in step S1, the silane coupling agent is one or more of KH-550, KH-560, and KH-570.

[0049] In step S2, the anti-precipitation agent solution is added into anhydrous ethanol and stirred at a first speed for a first preset time to obtain an anti-precipitation agent-ethanol dispersion.

[0050] In some embodiments, in step S2, the first rotation speed is 800-1200 rpm, and the first preset time is 10-20 min.

[0051] Preferably, the first rotation speed is 900-1100 rpm, and the first preset time is 13-17 min.

[0052] In step S3, spherical silver powder is added to the anti-precipitation agent-ethanol dispersion and stirred at a second speed for a second preset time to obtain the spherical silver powder-ethanol dispersion after anti-precipitation pretreatment.

[0053] In some embodiments, in step S3, the particle size of the spherical silver powder is 0.5-1.5 μm, and the purity is >99.99%.

[0054] Specifically, the spherical silver powder is prepared by a chemical reduction method.

[0055] In some embodiments, in step S3, the second rotation speed is 500-1000 rpm, and the second preset time is 10-20 min.

[0056] Preferably, the first rotation speed is 700-800 rpm, and the first preset time is 13-17 min.

[0057] In step S4, a dispersant is added to the spherical silver powder-ethanol dispersion after the anti-precipitation pretreatment and stirred at a third speed for a third preset time to obtain a material to be ground.

[0058] In some embodiments, in step S4, the dispersant is one or more of oleic acid, stearic acid, hexadecanoic acid, tetradecanol, and monoglyceride.

[0059] In some embodiments, in step S4, the third rotation speed is 500-1000 rpm, and the third preset time is 10-20 min.

[0060] Preferably, the first rotation speed is 700-800 rpm, and the first preset time is 13-17 min.

[0061] In step S5, the material to be ground is ground by a turbine sand mill to obtain a flaky silver powder-ethanol dispersion, and then the flaky silver powder-ethanol dispersion is dried and sieved to obtain flaky silver powder.

[0062] In some embodiments, in step S5, the grinding speed is 1000-3000 rpm, and the grinding time is 1-3 h.

[0063] Preferably, the grinding speed is 1500-2500 rpm, and the grinding time is 1.5-2.5 h.

[0064] Further preferably, the grinding speed is 2000 rpm and the grinding time is 2 h.

[0065] In some embodiments, in step S5, the grinding beads are zirconia beads with a diameter of 1 mm.

[0066] In some embodiments, in step S5, the drying temperature is 65-75° C., and the drying time is 8-12 hours.

[0067] Preferably, the drying temperature is 70° C., and the drying time is 10 h.

[0068] In some embodiments, in step S5, the screening is ultrasonic vibration screening, and the mesh size of the sieve used for screening is 200-350 meshes.

[0069] Preferably, the mesh size of the sieve used for screening is 250-300 meshes.

[0070] Example 1

[0071] In the first step, the anti-settling agent hydrogenated castor oil and the silane coupling agent KH-560 are mixed to obtain an anti-settling agent solution.

[0072] In the second step, the anti-precipitation agent solution was added into anhydrous ethanol and stirred at a rotation speed of 1000 rpm for 15 min to obtain an anti-precipitation agent-ethanol dispersion.

[0073] In the third step, the spherical silver powder is added into the anti-precipitation agent-ethanol dispersion and stirred at a rotation speed of 800 rpm for 15 minutes to obtain the spherical silver powder-ethanol dispersion after anti-precipitation pretreatment.

[0074] Among them, the mass of the anti-settling agent is 0.5% of the mass of the spherical silver powder, the mass ratio of the anti-settling agent to the silane coupling agent is 1:5, the mass ratio of the spherical silver powder to anhydrous ethanol is 1:2, and the particle size of the spherical silver powder prepared by the chemical reduction method is 0.96μm, and the purity is>99.99%.

[0075] The fourth step is to add the dispersant hexadecanoic acid into the spherical silver powder-ethanol dispersion after the anti-precipitation pretreatment and stir at a speed of 800 rpm for 15 minutes to obtain a material to be ground; wherein the mass of the dispersant is 0.1% of the mass of the spherical silver powder.

[0076] The fifth step is to grind the material to be ground at a rotation speed of 2000 rpm for 2 hours using a turbine sand mill to obtain a flaky silver powder-ethanol dispersion, and then dry the flaky silver powder-ethanol dispersion and perform ultrasonic vibration screening to obtain flaky silver powder; wherein, the grinding beads used for grinding are zirconia beads with a diameter of 1 mm, the drying temperature is 70°C, the drying time is 10 hours, and the mesh size of the sieve used for screening is 250-300 meshes.

[0077] Example 2

[0078] In the first step, the anti-settling agent fumed silica and the silane coupling agent KH-550 are mixed to obtain an anti-settling agent solution.

[0079] In the second step, the anti-precipitation agent solution was added into anhydrous ethanol and stirred at 800 rpm for 20 min to obtain an anti-precipitation agent-ethanol dispersion.

[0080] In the third step, the spherical silver powder is added into the anti-precipitation agent-ethanol dispersion and stirred at a rotation speed of 500 rpm for 20 minutes to obtain the spherical silver powder-ethanol dispersion after anti-precipitation pretreatment.

[0081] Among them, the mass of the anti-settling agent is 0.2% of the mass of the spherical silver powder, the mass ratio of the anti-settling agent to the silane coupling agent is 1:10, the mass ratio of the spherical silver powder to anhydrous ethanol is 2:3, the particle size of the spherical silver powder prepared by the chemical reduction method is 1.5μm, and the purity is>99.99%.

[0082] The fourth step is to add the dispersant oleic acid into the spherical silver powder-ethanol dispersion after the anti-precipitation pretreatment and stir at a speed of 500 rpm for 20 minutes to obtain a material to be ground; wherein the mass of the dispersant is 0.15% of the mass of the spherical silver powder.

[0083] The fifth step is to grind the material to be ground at a rotation speed of 3000 rpm for 1 hour using a turbine sand mill to obtain a flaky silver powder-ethanol dispersion, and then dry the flaky silver powder-ethanol dispersion and screen it by ultrasonic vibration to obtain flaky silver powder; wherein, the grinding beads used for grinding are zirconia beads with a diameter of 1 mm, the drying temperature is 75°C, the drying time is 8 hours, and the mesh size of the sieve used for screening is 200-250 meshes.

[0084] Example 3

[0085] In the first step, the anti-settling agent polyamide wax and the silane coupling agent KH-570 are mixed to obtain an anti-settling agent solution.

[0086] In the second step, the anti-precipitation agent solution was added into anhydrous ethanol and stirred at a rotation speed of 1200 rpm for 10 min to obtain an anti-precipitation agent-ethanol dispersion.

[0087] In the third step, the spherical silver powder is added into the anti-precipitation agent-ethanol dispersion and stirred at a rotation speed of 1000 rpm for 10 minutes to obtain the spherical silver powder-ethanol dispersion after anti-precipitation pretreatment.

[0088] Among them, the mass of the anti-settling agent is 0.1% of the mass of the spherical silver powder, the mass ratio of the anti-settling agent to the silane coupling agent is 1:2, the mass ratio of the spherical silver powder to anhydrous ethanol is 1:4, the particle size of the spherical silver powder prepared by the chemical reduction method is 0.5μm, and the purity is>99.99%.

[0089] In the fourth step, stearic acid as a dispersant is added into the spherical silver powder-ethanol dispersion after the anti-precipitation pretreatment and stirred at a speed of 1000 rpm for 10 minutes to obtain a material to be ground; wherein the mass of the dispersant is 0.05% of the mass of the spherical silver powder.

[0090] The fifth step is to grind the material to be ground at a rotation speed of 1000 rpm for 3 hours using a turbine sand mill to obtain a flaky silver powder-ethanol dispersion, and then dry the flaky silver powder-ethanol dispersion and screen it by ultrasonic vibration to obtain flaky silver powder; wherein, the grinding beads used for grinding are zirconia beads with a diameter of 1 mm, the drying temperature is 65°C, the drying time is 12 hours, and the mesh size of the sieve used for screening is 300-350 meshes.

[0091] The flaky silver powders prepared in Examples 1-3 were respectively formulated into silver pastes with a silver content of 32% using a vinyl chloride vinyl acetate resin system. The performance parameters of the flaky silver powders prepared in Examples 1-3 and the formulated silver pastes are shown in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] As can be seen from Table 1, the flaky silver powder prepared by the method of the present invention has the characteristics of low bulk density and high specific surface area. After being prepared into silver paste, the silver paste has a viscosity suitable for printing, and has good electrical conductivity and oxidation resistance.

[0096] In summary, the solution proposed by the present invention has the following technical effects:

[0097] The present invention controls the solid-liquid ratio of the wet abrasive to obtain a spherical silver powder-ethanol dispersion with good fluidity and uniform dispersion as a slurry, which can not only meet the smooth circulation of materials under the action of the pneumatic diaphragm pump of the turbine sand mill, but also improve the grinding efficiency. In addition, the pretreatment of the low-solid content wet abrasive with an anti-settling agent and a silane coupling agent can effectively prevent settling, ensure that the spherical silver powder particles are uniformly ground during the cyclic grinding process, make the flaking degree more uniform, and thus reduce the loose density of the flaky silver powder.

[0098] In addition, the turbine sand mill used in the present invention greatly improves the grinding efficiency compared with the traditional drum ball mill, and the flaking process is fast, and the grinding time is controlled within 1-3 hours; on the other hand, compared with the pin-type sand mill, the material can be ground more gently and finely in the grinding chamber, and the rotation of the turbine drives the grinding medium to produce swirl and axial movement, generating uniform and strong shear force, allowing the material to flow in the annular gap and be better dispersed, and the loss of the grinding medium is lower.

[0099] In addition, the flaky silver powder prepared by the method of the present invention has the characteristics of low bulk density, good oxidation resistance and good matching with the organic system of silver paste.

[0100] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A method for preparing low bulk density flaky silver powder using a turbine sand mill, characterized in that: The method comprises the following steps: Step S1, mixing an anti-settling agent and a silane coupling agent to obtain an anti-settling agent solution; Step S2, adding the anti-precipitation agent solution into anhydrous ethanol and stirring at a first speed for a first preset time to obtain an anti-precipitation agent-ethanol dispersion; Step S3, adding the spherical silver powder into the anti-precipitation agent-ethanol dispersion and stirring at a second speed for a second preset time to obtain the spherical silver powder-ethanol dispersion after anti-precipitation pretreatment; Step S4, adding a dispersant to the spherical silver powder-ethanol dispersion after the anti-precipitation pretreatment and stirring at a third speed for a third preset time to obtain a material to be ground; Step S5, grinding the material to be ground by a turbine sand mill to obtain a flaky silver powder-ethanol dispersion, and then drying and sieving the flaky silver powder-ethanol dispersion to obtain flaky silver powder; Among them, the mass of the anti-settling agent is 0.2%-1% of the mass of the spherical silver powder, the mass ratio of the anti-settling agent to the silane coupling agent is 1:10 to 1:2, the mass ratio of the spherical silver powder to anhydrous ethanol is 1:4 to 2:3, and the mass of the dispersant is 0.05%-0.15% of the mass of the spherical silver powder.

2. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In the step S1, the anti-settling agent is one or more of fumed silica, hydrogenated castor oil, and polyamide wax.

3. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In the step S1, the silane coupling agent is one or more of KH-550, KH-560, and KH-570.

4. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In the step S2, the first rotation speed is 800-1200 rpm, and the first preset time is 10-20 min.

5. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In the step S3, the particle size of the spherical silver powder is 0.5-1.5 μm, and the purity is >99.99%.

6. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In the step S3, the second rotation speed is 500-1000 rpm, and the second preset time is 10-20 min.

7. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In step S4, the dispersant is one or more of oleic acid, stearic acid, hexadecanoic acid, tetradecanol, and monoglyceride.

8. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In the step S4, the third rotation speed is 500-1000 rpm, and the third preset time is 10-20 min.

9. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In the step S5, the grinding speed is 1000-3000 rpm, and the grinding time is 1-3 hours.

10. The method for preparing low bulk density flaky silver powder by a turbine sand mill according to claim 1, characterized in that: In the step S5, the grinding beads are zirconia beads with a diameter of 1 mm.

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