Preparation equipment and preparation method of porous silver powder with high sintering activity

Abstract

The invention discloses preparation equipment and a preparation method of porous silver powder with high sintering activity. The preparation equipment comprises a group of raw material preparation devices and a continuous mixing reaction device, the continuous mixing reaction device comprises a primary mixing cavity, the upper end of which is connected in parallel with a pump through a feeding guide pipe and is connected to the discharging end of one group of raw material preparation device; the retractable pipe fitting is connected to the lower end part of the feeding guide pipe, a liquid distribution container is hermetically and rotatably mounted on the bottom side of the retractable pipe fitting, and a plurality of corresponding liquid outlet pipes are uniformly distributed on the liquid distribution container; the upper end part of the secondary material mixing cavity is communicated and connected to the lower end part of the primary material mixing cavity through a plurality of uniformly distributed material guide pipes, and the discharge ends of the material guide pipes are respectively and movably screwed with corresponding material distribution pipes downwards through spiral grooves. According to the method, continuous preparation and processing of the silver powder can be achieved, so that oxidation liquid and reduction liquid are rapidly mixed, full reaction is achieved, and the porous silver powder with high sintering activity is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation and processing of highly sinterable porous silver powder, and specifically refers to a preparation device and a preparation method for highly sinterable porous silver powder. Background Art

[0002] Silver paste is widely used in semiconductor metallization, especially in silicon solar cells. Silver powder is the material with the highest content in silver paste, and its morphology and structure determine its properties, especially the sintering activity. With the development of the industry, the requirements for the conversion efficiency of solar cells are getting higher and higher. Currently, laser-assisted sintering technology (Laser-enhanced contact optimization, LECO) is generally used in silicon solar cells to improve the contact between metal electrodes and silicon wafers in solar cells, so that higher current can be obtained under the same line width, or finer lines can be obtained under the same current, to improve the conversion efficiency of solar cells. LECO requires silver powder to have higher sintering activity to match a larger sintering temperature window.

[0003] In the existing silver powder preparation process, due to the limitation of processing equipment, the synthesis reaction of silver powder can only be carried out through an intermittent reaction kettle, and a large amount of polyvinylpyrrolidone (PVP) is added as a surfactant to ensure the dispersion and uniformity of silver powder. It not only has low preparation efficiency, but also the silver powder obtained has coarse grains and high crystallinity, resulting in low sintering activity of the silver powder. The solar cells made of this silver powder have a lower open voltage and a higher series resistance, and ultimately a lower photoelectric conversion efficiency.

[0004] Therefore, the research purpose of the present invention is to design a preparation device and a preparation method for highly sinterable porous silver powder that can realize the continuous preparation and processing of silver powder, facilitate the rapid mixing of oxidation liquid and reduction liquid, and achieve full reaction, so as to effectively improve the preparation efficiency of products and obtain highly sinterable porous silver powder with high sintering activity. Summary of the Invention

[0005] In view of the above technical problems existing in the prior art, the present invention provides a preparation device and a preparation method for highly sinterable porous silver powder, which can effectively solve the above technical problems existing in the prior art.

[0006] The technical solution of the present invention is as follows: A preparation device for highly sinterable porous silver powder, comprising: a set of raw material preparation devices and a continuous mixing and reaction device, and the continuous mixing and reaction device includes: A primary mixing chamber, with a corresponding feed conduit installed through the upper end, and the upper end of the feed conduit is connected in parallel by a pump to the discharge ends of the set of raw material preparation devices; A collapsible pipe fitting is connected to the lower end of the feed conduit. A liquid distribution container communicating with the collapsible pipe fitting is rotatably and sealingly installed on the bottom side of the collapsible pipe fitting. A plurality of corresponding liquid outlet pipes are evenly arranged in the radial direction of the liquid distribution container. The lengths between adjacent two liquid outlet pipes are set differently, and the liquid outlet ends of the liquid outlet pipes are respectively arranged in a constricted shape and are horizontally folded backward in an arc shape. A secondary mixing chamber, the upper end of which is connected to the lower end of the primary mixing chamber through a plurality of evenly arranged guide pipes. The discharge ends of the guide pipes are respectively threadedly connected with corresponding cloth pipes that can move downward through spiral grooves. The discharge ends of the cloth pipes are respectively fixedly connected with a corresponding fixed flange. A plurality of corresponding installation grooves are respectively arranged on the fixed flange, and corresponding stirring rods are respectively swingably installed in the installation grooves. Spiral springs sleeved around the cloth pipes are respectively fixedly connected between the fixed flange and the guide pipes.

[0007] The raw material preparation device respectively includes a raw material preparation tank. In the raw material preparation tank, a stirring shaft driven by a corresponding driving motor is rotatably installed. A group of corresponding first stirring plates are swingably installed up and down in the middle of the stirring shaft. One end of the first stirring plate not connected to the stirring shaft is inclined downward, and a corresponding second stirring plate is fixedly connected upward in the middle of the first stirring plate. A corresponding third stirring plate is respectively swingably installed at the upper end of the second stirring plate. A corresponding buffer spring is respectively fixedly connected between the third stirring plate and the corresponding second stirring plate.

[0008] Corresponding feeding ports are respectively arranged on the upper parts of the raw material preparation tanks, and corresponding discharge pipes are respectively arranged at the bottoms of the raw material preparation tanks. The upper ends of the feed conduits are connected in parallel by pumps to the discharge ends of the discharge pipes.

[0009] The collapsible pipe fitting is made of a metal bellows. The liquid distribution container includes a cloth container body arranged in a barrel shape. The upper end of the cloth container body is connected inward in a stepped shape with a connecting sleeve having a diameter smaller than that of the cloth container body. The connecting sleeve is rotatably installed on the bottom side of the collapsible pipe fitting through a sealing bearing.

[0010] On the outer side of the end of the stirring rod not installed on the fixed flange, there is a pressure-receiving slope surface with the same helix direction as the spiral groove; on the inner side of the other end of the stirring rod not installed on the fixed flange, there is a blocking slope surface with the same helix direction as the spiral groove.

[0011] A preparation method of high-sintering-activity porous silver powder, based on the above-mentioned preparation equipment for high-sintering-activity porous silver powder, includes the following specific steps: S1. Feed silver nitrate and an aqueous solution into a raw material preparation tank of a raw material preparation device, stir to dissolve silver nitrate in the aqueous solution to form a silver nitrate solution, then add ammonia water, and stir evenly to form a silver ammonia solution; S2. Feed a reducing agent and an aqueous solution into a raw material preparation tank of another raw material preparation device, stir to dissolve the reducing agent in the aqueous solution, then add surfactant A and surfactant B, and stir evenly to form a reducing agent solution; S3. By means of pumping, mix and transport the silver ammonia solution and the reducing agent solution in proportion through the primary mixing chamber and the secondary mixing chamber of the continuous mixing reaction device for continuous mixing reaction. The highly sinterable active porous silver powder obtained by the reaction is collected after being output from the secondary mixing chamber.

[0012] The concentration of the silver nitrate solution in step S1 is 0.05 - 0.3 mol / L, and the molar ratio of ammonia water to silver nitrate is 2:1 - 3:1.

[0013] The concentration of the reducing agent in step S2 is 0.075 - 0.45 mol / L, the concentration of surfactant A is 0.2 - 2%, and the concentration of surfactant B is 1 - 5%.

[0014] The reducing agent is one or two of ascorbic acid, formaldehyde, glucose, and hydrogen peroxide.

[0015] The surfactant A is one of isododecanol, isotetradecanol, and isohexadecanol; the surfactant B is one of cetyltrimethylammonium bromide, sodium dodecyl sulfate, dodecyldimethylbetaine, and sodium dodecylaminopropionate.

[0016] Advantages of the present invention: 1) When preparing silver powder in the present invention, an oxidation solution (silver ammonia solution) and a reduction solution (reducing agent solution) are respectively prepared by a set of raw material preparation devices, and then the prepared oxidation solution and reduction solution are pumped to the feed conduit and output through the liquid outlet pipes in the radial direction of the liquid distribution container. Since the liquid outlet ends of the liquid outlet pipes are respectively arranged in a constricted shape and are horizontally turned backward in an arc shape, when the oxidation solution and the reduction solution are output and enter the primary mixing chamber, a horizontal forward thrust can be formed, thereby driving the liquid distribution container to rotate to stir the materials in the primary mixing chamber, and the scouring force formed by the materials ejected from different positions can also significantly enhance the stirring effect on the materials in the primary mixing chamber, so as to realize the continuous preparation of silver powder, greatly improve the production capacity, and thus solve the problems of limited single-batch output of traditional batch reactors and unstable quality during scale-up production.

[0017] 2) The driving liquid distribution container of the present invention is connected to the feeding conduit through a collapsible pipe fitting. Therefore, the flow pressure of the material can be controlled by controlling the pumping amounts of the oxidation liquid and the reduction liquid. When the material flow pressure increases, the collapsible pipe fitting is compressed and elongated, and the liquid distribution container descends and the rotation speed increases; when the material flow pressure decreases, the collapsible pipe fitting retracts, and the liquid distribution container ascends and the rotation speed decreases. Thus, the liquid distribution container during rotation can be effectively lifted and the rotation speed adjusted to further ensure the mixing effect of the material entering the primary mixing chamber, thereby further realizing the continuous preparation of silver powder.

[0018] 3) On the basis of the primary mixing chamber, the present invention further has a secondary mixing chamber, the upper end of which is connected to the lower end of the primary mixing chamber through a plurality of uniformly arranged guide pipes. The discharge ends of the guide pipes are respectively screwed downwardly and movably along spiral grooves with corresponding cloth pipes. The discharge ends of the cloth pipes are respectively fixedly connected with a ring of fixed flanges. Stirring rods are respectively swingably mounted on the fixed flanges, and spiral springs sleeved around the cloth pipes are respectively fixedly connected between the fixed flanges and the guide pipes. When the material flow pressure in the primary mixing chamber increases, the material pressure flowing through the cloth pipe also increases. At this time, the cloth pipe is compressed and spirally descends, and the spiral spring is stretched and wound; when the material flow pressure in the primary mixing chamber decreases, the material pressure flowing through the cloth pipe also decreases. At this time, the cloth pipe rotates upward and resets under the drive of the spiral spring, thereby driving the stirring rods to rotate at different heights to ensure the mixing effect of the material entering the secondary mixing chamber, thereby further realizing the continuous preparation of silver powder.

[0019] 4) When the material flow pressure increases and the cloth pipe is compressed and spirally descends, it is necessary to form a tensile force and a winding force on the spiral spring. At this time, if it is also necessary to provide the stirring force of the stirring rod on the material, it is difficult to achieve; for this reason, the stirring rod of the present invention is provided with a compression slope surface on the outer side of the end not installed on the fixed flange, and the spiral direction of which is the same as that of the spiral groove. When the cloth pipe spirally descends, the stirring rod is formed with an internal thrust by the material and does not swing downward, thereby reducing the resistance when the cloth pipe spirally descends to ensure the practical effect of the present invention.

[0020] 5) The inner side of the other end of the stirring rod of the present invention not installed on the fixed flange is provided with a blocking and pushing slope surface with the same spiral direction as the spiral groove, so that when the cloth pipe rotates upward and resets under the drive of the spiral spring, the stirring rod can be formed with an external thrust by the material and swing downward to ensure that the stirring rod can form a mixing effect on the material during the upward rotation process of the cloth pipe, thereby further ensuring the practical effect of the present invention.

[0021] 6) Under the combined action of various surfactants, the product of the present invention forms submicron and nanoscale bubbles, providing a soft template, enabling the synthesized spherical silver powder to have a porous structure inside, thereby affecting Ostwald ripening, reducing the grain size of silver particles, and at the same time further increasing the specific surface area of the silver powder and improving its sintering activity. After testing, the silver powder prepared by the preparation method of the present invention has its grain size reduced to 21 nm, the series resistance reduced to 0.002 Ω, and the conversion efficiency increased to 21%; and it can be clearly seen from the comparison of the SEM electron microscope images that the porosity of the silver powder prepared by the preparation method of the present invention is significantly increased and the sintering activity of the silver powder is improved.

[0022] 7) The raw material preparation device of the present invention includes a raw material preparation tank. In the middle of the stirring shaft arranged in the raw material preparation tank, a group of first stirring plates are swingably installed up and down. One end of the first stirring plate that is not connected to the stirring shaft is inclined downward, and a second stirring plate is fixedly connected upward at the middle of the first stirring plate. Third stirring plates are respectively swingably installed back and forth at the upper ends of the second stirring plates, and buffer springs are fixedly connected between the third stirring plates and the second stirring plates. During the raw material preparation process, the mixing effect can be improved by controlling the driving speed of the stirring shaft. When the speed of the stirring shaft increases, the pressure on the third stirring plates increases and they swing backward, thereby forming a force-receiving slope to drive the second stirring plate and the first stirring plate to swing upward as a whole; when the speed of the stirring shaft decreases, the third stirring plates reset under the action of the buffer springs, and the second stirring plate and the first stirring plate as a whole drop to the original height. In this way, the mixing effect during the raw material preparation process can be effectively improved by controlling the driving speed of the stirring shaft, thereby further improving the use effect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of the present invention.

[0024] Figure 2 is a cross-sectional view of the raw material preparation device.

[0025] Figure 3 is an assembly schematic diagram of the stirring shaft, the first stirring plate, the second stirring plate and the third stirring plate.

[0026] Figure 4 is a cross-sectional view of the continuous mixing reaction device.

[0027] Figure 5 is an assembly schematic diagram of the liquid distribution container, the collapsible pipe fitting and the feed conduit.

[0028] Figure 6 is a structural schematic diagram of the cloth pipe installed with stirring rods through fixed convex edges.

[0029] Figure 7 is a SEM electron microscope image of the silver powder prepared by the present invention.

[0030] In the attached drawings: raw material preparation device 1, raw material preparation tank 101, drive motor 102, stirring shaft 103, first stirring plate 104, second stirring plate 105, third stirring plate 106, buffer spring 107, continuous mixing reaction device 2, primary mixing chamber 201, feed conduit 202, collapsible pipe fitting 203, liquid distribution container 204, liquid distribution container body 2041, connecting sleeve 2042, liquid outlet pipe 205, secondary mixing chamber 206, material guiding pipe 207, cloth distributing pipe 208, stirring rod member 209, spiral spring 2010, fixed flange 3, mounting groove 301, feeding port 4, discharging pipe 5, sealing bearing 6, pressure receiving slope 7, pushing slope 8. Specific Embodiment

[0031] For the convenience of those skilled in the art to understand, the embodiments will now be further described in detail in conjunction with the attached drawings for the structure of the present invention: Embodiment 1: Reference Figure 1-6 , a preparation device for highly sinterable porous silver powder, comprising: a set of raw material preparation devices 1 and a continuous mixing reaction device 2, and the continuous mixing reaction device 2 includes: A primary mixing chamber 201 is installed through the upper end with a corresponding feed conduit 202, and the upper end of the feed conduit 202 is connected in parallel by a pump to the discharge end of the set of raw material preparation devices 1; A collapsible pipe fitting 203 is connected to the lower end of the feed conduit 202, and a liquid distribution container 204 communicating with the collapsible pipe fitting 203 is hermetically and rotatably installed on the bottom side of the collapsible pipe fitting 203. A plurality of corresponding liquid outlet pipes 205 are evenly arranged in the radial direction of the liquid distribution container 204. The lengths between adjacent two liquid outlet pipes 205 are set differently, and the liquid outlet ends of the liquid outlet pipes 205 are respectively arranged in a constricted shape and horizontally folded backward in an arc shape; A secondary mixing chamber 206 has its upper end connected to the lower end of the primary mixing chamber 201 through a plurality of evenly arranged material guiding pipes 207. The discharge ends of the material guiding pipes 207 are respectively screwed downwardly and movably through spiral grooves with corresponding cloth distributing pipes 208. The discharge ends of the cloth distributing pipes 208 are respectively fixedly connected with a corresponding fixed flange 3 in a circle. A plurality of corresponding mounting grooves 301 are respectively arranged on the fixed flange 3, and corresponding stirring rod members 209 are respectively swingably installed in the mounting grooves 301. A spiral spring 2010 sleeved on the outer periphery of the cloth distributing pipe 208 is respectively fixedly connected between the fixed flange 3 and the material guiding pipe 207.

[0032] When preparing silver powder in the present invention, an oxidation solution (silver ammonia solution) and a reduction solution (reductant solution) are respectively prepared by a set of raw material preparation devices 1, and then the prepared oxidation solution and reduction solution are pumped to the feed conduit 202 and output through the liquid outlet pipe 205 in the radial direction of the liquid distribution container 204. Since the liquid outlet ends of the liquid outlet pipes 205 are respectively arranged in a constricted shape and horizontally folded backward in an arc shape, during the process of the oxidation solution and the reduction solution being output and entering the primary mixing chamber 201, a horizontal forward thrust can be formed, thereby driving the liquid distribution container 204 to rotate, so as to stir the materials in the primary mixing chamber 201, and the scouring force formed by the materials ejected from different positions can also significantly enhance the stirring effect on the materials in the primary mixing chamber 201, thereby realizing the continuous preparation of silver powder, greatly improving the production capacity, and further solving the problems such as the limited single-batch output of traditional batch reactors and the unstable quality during scale-up production.

[0033] Moreover, the driving liquid distribution container 204 and the feed conduit 202 of the present invention are connected through a collapsible pipe fitting 203. Therefore, the flow pressure of the materials can be controlled by controlling the pumping amounts of the oxidation solution and the reduction solution. When the material flow pressure increases, the collapsible pipe fitting 203 is compressed and elongated, the liquid distribution container 204 descends and the rotation speed increases; when the material flow pressure decreases, the collapsible pipe fitting 203 retracts, the liquid distribution container 204 ascends and the rotation speed decreases. Thus, the lifting drive and speed adjustment of the rotating liquid distribution container 204 can be effectively carried out to further ensure the mixing effect of the materials entering the primary mixing chamber 201, and further realize the continuous preparation of silver powder.

[0034] Based on the primary mixing chamber 201, the present invention is further provided with a secondary mixing chamber 206. Its upper end is connected to the lower end of the primary mixing chamber 201 through a plurality of uniformly arranged guide pipes 207. The discharge ends of the guide pipes 207 are respectively screwed downward movably along spiral grooves with corresponding cloth pipes 208. The discharge ends of the cloth pipes 208 are respectively fixedly connected with a circle of fixed flanges 3. Stirring rods 209 are respectively swingably installed on the fixed flanges 3, and spiral springs 2010 sleeved on the periphery of the cloth pipes are respectively fixedly connected between the fixed flanges 3 and the guide pipes 207. When the material flow pressure in the primary mixing chamber 201 increases, the material pressure flowing through the cloth pipe 208 will also increase. At this time, the cloth pipe 208 is pressed and spirally descends, and the spiral spring 2010 is stretched and wound; when the material flow pressure in the primary mixing chamber 201 decreases, the material pressure flowing through the cloth pipe 208 will also decrease. At this time, the cloth pipe 208 rotates and ascends to reset under the drive of the spiral spring 2010, thereby driving the stirring rods 209 to rotate at different heights to ensure the mixing effect of the materials entering the secondary mixing chamber 206, and further realizing the continuous preparation of silver powder.

[0035] The raw material preparation device 1 respectively includes a raw material preparation tank 101. A stirring shaft 103 driven by a corresponding driving motor 102 is rotatably installed in the raw material preparation tank 101. A group of corresponding first stirring plates 104 are swingably installed up and down in the middle of the stirring shaft 103. One end of the first stirring plate 104 not connected to the stirring shaft 103 is inclined downward, and a corresponding second stirring plate 105 is fixedly connected upward in the middle of the first stirring plate 104. Corresponding third stirring plates 106 are swingably installed back and forth at the upper ends of the second stirring plates 105. Corresponding buffer springs 107 are fixedly connected between the third stirring plates 106 and the corresponding second stirring plates 105.

[0036] During the raw material preparation process, the mixing effect can be improved by controlling the driving speed of the stirring shaft 103. When the rotation speed of the stirring shaft 103 increases, the pressure on the third stirring plate 106 increases and it swings backward, thus forming a force-receiving slope to drive the second stirring plate 105 and the first stirring plate 104 to swing upward as a whole; when the rotation speed of the stirring shaft 103 decreases, the third stirring plate 106 resets under the action of the buffer spring 107, and the second stirring plate 105 and the first stirring plate 104 descend as a whole to the original height. In this way, the mixing effect during the raw material preparation process can be effectively improved by controlling the driving speed of the stirring shaft 103, thereby further improving the use effect of the present invention.

[0037] Corresponding feeding ports 4 are respectively arranged at the upper parts of the raw material preparation tanks 101, and corresponding discharge pipes 5 are respectively arranged at the bottoms of the raw material preparation tanks 101. The upper ends of the feed conduits 202 are connected in parallel to the discharge ends of the discharge pipes 5 by pumps.

[0038] The collapsible pipe fitting 203 is made of a metal bellows. The liquid distribution container 204 includes a cloth container body 2041 arranged in a barrel shape. A stepped connection sleeve 2042 with a diameter smaller than that of the cloth container body 2041 is connected inward in a stepped manner at the upper end of the cloth container body 2041. The connection sleeve 2042 is rotatably installed on the bottom side of the collapsible pipe fitting 203 through a sealing bearing 6.

[0039] A pressure-receiving slope 7 with the same helix direction as the spiral groove is arranged on the outer side of one end of the stirring rod 209 not installed on the fixed flange 2; a blocking and pushing slope 8 with the same helix direction as the spiral groove is arranged on the inner side of the other end of the stirring rod 209 not installed on the fixed flange 3.

[0040] When the material flow pressure increases and the cloth tube 208 is pressed and spirally descends, it is necessary to form a tensile force and a winding force on the spiral spring 1010. At this time, if it is also necessary to provide the mixing force of the mixing rod 209 on the material, it is difficult to achieve. For this reason, on the outer side of one end of the mixing rod 209 of the present invention that is not installed on the fixed flange 3, a compression slope 7 with the same spiral direction as the spiral groove is provided. When the cloth tube 208 spirally descends, the mixing rod 209 is formed with an internal thrust by the material and does not swing downward, thereby reducing the resistance when the cloth tube 208 spirally descends to ensure the practical effect of the present invention. When the cloth tube 208 rotates upward and resets under the drive of the spiral spring 2010, the blocking and pushing slope 8 of the mixing rod 209 can be formed with an external thrust by the material and swing downward to ensure that the mixing rod 209 can form a mixing effect on the material during the upward rotation process of the cloth tube 208, thereby further ensuring the practical effect of the present invention.

[0041] Embodiment 2: A preparation method of highly sinterable active porous silver powder, based on the preparation equipment of highly sinterable active porous silver powder described in the above-mentioned Embodiment 1, includes the following specific steps: S1, Feed silver nitrate and aqueous solution into the raw material preparation tank 101 of a raw material preparation device 1, stir to dissolve silver nitrate in the aqueous solution to form a silver nitrate solution, and then add ammonia water. After stirring evenly, a silver ammonia solution is formed. Among them, the concentration of the silver nitrate solution is 0.15 mol / L, and the molar ratio of ammonia water to silver nitrate is 2.5:1; S2, Feed the reducing agent and aqueous solution into the raw material preparation tank 101 of another raw material preparation device 1, stir to dissolve the reducing agent in the aqueous solution, and then add surfactant A and surfactant B. After stirring evenly, a reducing agent solution is formed. Among them, the concentration of the reducing agent is 0.25 mol / L, the concentration of surfactant A is 0.15%, and the concentration of surfactant B is 3.5%; S3, Through a pumping method, mix and transport the silver ammonia solution and the reducing agent solution in a ratio of 1:1 through the primary mixing chamber 201 and the secondary mixing chamber 206 of the continuous mixing reaction device 2 for continuous mixing reaction. The highly sinterable active porous silver powder obtained by the reaction is collected after being output from the secondary mixing chamber 206.

[0042] The reducing agent is ascorbic acid and formaldehyde. The surfactant A is isocetyl alcohol; the surfactant B is dodecyl dimethyl betaine.

[0043] The product of the present invention forms sub-micron and nano-scale bubbles under the combined action of various surfactants, providing a soft template, so that the synthesized spherical silver powder has a porous structure inside, thereby affecting Ostwald ripening, reducing the grain size of silver particles, and at the same time further increasing the specific surface area of the silver powder and improving its sintering activity. After testing, the silver powder prepared by the preparation method of the present invention has a grain size reduced to 21 nm, a series resistance reduced to 0.002 Ω, and a conversion efficiency increased to 21%. Refer to Figure 7 , it can be seen from the SEM electron microscope image that: the porosity of the silver powder prepared by the preparation method of the present invention is significantly increased, and the sintering activity of the silver powder is improved.

[0044] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. An apparatus for preparing highly sinterable porous silver powder, comprising: A set of raw material preparation devices (1) and a continuous mixing and reaction device (2), characterized in that the continuous mixing and reaction device (2) includes: A primary mixing chamber (201), with a corresponding feed conduit (202) installed through the upper end. The upper end of the feed conduit (202) is connected in parallel by a pump to the discharge end of a set of the raw material preparation devices (1). A collapsible pipe fitting (203), connected to the lower end of the feed conduit (202). A liquid distribution container (204) communicating with the collapsible pipe fitting (203) is hermetically and rotatably installed on the bottom side of the collapsible pipe fitting (203). A number of corresponding liquid outlet pipes (205) are evenly distributed in the radial direction of the liquid distribution container (204). The lengths between adjacent two liquid outlet pipes (205) are set differently, and the liquid outlet ends of the liquid outlet pipes (205) are respectively set in a constricted shape and are horizontally turned backward in an arc shape. A secondary mixing chamber (206), with its upper end connected to the lower end of the primary mixing chamber (201) through a number of evenly distributed guide pipes (207). The discharge ends of the guide pipes (207) are respectively screwed downwardly and movably through spiral grooves with corresponding cloth pipes (208). The discharge ends of the cloth pipes (208) are respectively fixedly connected with a corresponding fixed flange (3) in a circle. A number of corresponding installation grooves (301) are respectively arranged on the fixed flange (3). Corresponding stirring rods (209) are respectively swingably installed in the installation grooves (301). A spiral spring (2010) sleeved on the periphery of the cloth pipe (208) is respectively fixedly connected between the fixed flange (3) and the guide pipe (207).

2. The preparation equipment of a highly sinterable active porous silver powder according to claim 1, characterized in that, The raw material preparation devices (1) respectively include raw material preparation tanks (101). Stirring shafts (103) driven by corresponding drive motors (102) are respectively rotatably installed in the raw material preparation tanks (101). A set of corresponding first stirring plates (104) are swingably installed up and down in the middle of the stirring shafts (103). One end of the first stirring plate (104) not connected to the stirring shaft (103) is inclined downward. A corresponding second stirring plate (105) is fixedly connected upwardly and obliquely in the middle of the first stirring plate (104). Corresponding third stirring plates (106) are respectively swingably installed back and forth at the upper end of the second stirring plate (105). A corresponding buffer spring (107) is respectively fixedly connected between the third stirring plate (106) and the corresponding second stirring plate (105).

3. The preparation equipment of a highly sinterable porous silver powder according to claim 2, characterized in that, Corresponding feeding ports (4) are respectively arranged on the upper parts of the raw material preparation tanks (101), and corresponding discharge pipes (5) are respectively arranged on the bottoms of the raw material preparation tanks (101). The upper end of the feed conduit (202) is connected in parallel by a pump to the discharge end of the discharge pipe (5).

4. The preparation equipment of a highly sinterable active porous silver powder according to claim 1, characterized in that, The collapsible pipe fitting (203) adopts a metal bellows. The liquid distribution container (204) includes a cloth container body (2041) arranged in a barrel shape. An adapter sleeve (2042) with a diameter smaller than that of the cloth container body (2041) is connected inward in a stepped manner at the upper end of the cloth container body (2041). The adapter sleeve (2042) is rotatably mounted on the bottom side of the collapsible pipe fitting (203) through a sealed bearing (6).

5. The preparation equipment of a highly sinterable active porous silver powder according to claim 1, characterized in that, On the outer side of one end of the fixed flange (3) where the stirring rod member (209) is not installed, there is a pressure-receiving slope surface (7) with the same spiral direction as the spiral groove; on the inner side of the other end of the fixed flange (3) where the stirring rod member (209) is not installed, there is a blocking slope surface (8) with the same spiral direction as the spiral groove.

6. A preparation method of highly sinterable porous silver powder, based on the preparation equipment of highly sinterable porous silver powder described in any one of the above claims 1-5, characterized in that, It includes the following specific steps: S1, Feed silver nitrate and an aqueous solution into the raw material preparation tank (101) of a raw material preparation device (1), stir to dissolve silver nitrate in the aqueous solution to form a silver nitrate solution, and then add ammonia water. After stirring evenly, a silver ammonia solution is formed; S2, Feed a reducing agent and an aqueous solution into the raw material preparation tank (101) of another raw material preparation device (1), stir to dissolve the reducing agent in the aqueous solution, and then add surfactant A and surfactant B. After stirring evenly, a reducing agent solution is formed; S3, Through a pumping method, mix and transport the silver ammonia solution and the reducing agent solution in proportion through the primary mixing chamber (201) and the secondary mixing chamber (206) of the continuous mixing reaction device (2) for continuous mixing reaction. The highly sinterable active porous silver powder obtained from the reaction is collected after being output from the secondary mixing chamber (206).

7. The preparation method of a highly sinterable porous silver powder according to claim 6, characterized in that, The concentration of the silver nitrate solution in step S1 is 0.05 - 0.3 mol / L, and the molar ratio of ammonia water to silver nitrate is 2:1 - 3:

1.

8. The preparation method of a highly sinterable porous silver powder according to claim 7, characterized in that, The concentration of the reducing agent in step S2 is 0.075 - 0.45 mol / L, the concentration of surfactant A is 0.2 - 2%, and the concentration of surfactant B is 1 - 5%.

9. The preparation method of a highly sinterable active porous silver powder according to claim 8, characterized in that, The reducing agent is one or two of ascorbic acid, formaldehyde, glucose, and hydrogen peroxide.

10. The preparation method of a highly sinterable active porous silver powder according to claim 9, characterized in that, The surfactant A is one of isododecanol, isotetradecanol, and isohexadecanol; the surfactant B is one of cetyltrimethylammonium bromide, sodium dodecyl sulfate, dodecyldimethylbetaine, and sodium dodecylaminopropionate.

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