Powder coating apparatus and powder dispersion apparatus

Abstract

To provide a device and a method for coating powder and a device and a method for dispersing powder capable of improving the dispersibility of powder and the efficiency of coating treatment.SOLUTION: A coating device 1 comprises a dispersing / mixing part 2, a conveying part 3, and a collecting part 4. A raw material powder and a coating liquid are supplied to the dispersing / mixing part 2 in the form of a slurry. In the dispersing / mixing part 2, the slurry (mixture) in which the raw material powder and the coating liquid have been mixed is dispersed by an air flow of a high pressure fluid into a powder having a film of the coating liquid adhering to its surface. The powder is introduced from the dispersing / mixing part 2 to the conveying part 3 and is conveyed through the conveying part 3 toward the collecting part 4. During this conveyance, the coating liquid adhering to the particle surfaces dries, producing a powder in which the particle surfaces are coated with a precursor. A powder flow introduced into the collecting part 4 passes through a bag filter 54. This causes the powder to be captured by the bag filter 54.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a powder coating apparatus and Powder dispersion equipment to

Background Art

[0002] }In the technology of surface modification and compounding, different fine particles can be bonded to particles, and by coating the surface of the particles with the fine particles, various functionalities can be imparted to the powder. This technology of surface modification and compounding is widely used in fields such as food, pharmaceuticals, and cosmetics, and is also used for materials used in electronic components and batteries to improve their electrical properties.

[0003] As a method of powder coating, a coating liquid in which fine powder as a coating material is dispersed in a solvent is adhered to raw material powder as a main raw material, and the coating liquid is dried to form a coating layer of fine powder on the surface of the raw material powder (particles).

[0004] For example, Patent Document 1 discloses an apparatus for performing a coating process in which a fluidizing gas is introduced into a container containing raw material powder, and a coating liquid is sprayed onto the raw material powder fluidized by the fluidizing gas to form a coating layer on the raw material powder. In such an apparatus, in the coating process, when the coating liquid is atomized and adhered, if the spraying speed is high, it will aggregate due to the liquid bridging force, so it may take time for coating, and since the coating process is a batch process, the entire process also takes a long time.

[0005] On the other hand, Patent Document 2 discloses an apparatus in which air is swirled in a cyclone-shaped container, and powder and spraying of a coating liquid are mixed into the swirling air flow, a coating layer is formed on the powder on the transport path following the container, and the powder after the coating process is collected.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2011-56348 [Patent Document 2] Japanese Patent Application Publication No. 2-107366 [Overview of the project] [Problems that the invention aims to solve]

[0007] The raw material powders are currently trending towards finer particle size, and this finer particle size increases the cohesiveness of the raw material powders. Therefore, higher dispersibility is desired in coating equipment. Furthermore, in all prior art equipment, there is a problem that it takes a considerable amount of time to form a uniform coating layer on the surface of the raw material powders while maintaining a state where the raw material powders do not cohesive. In addition, recovery loss due to powder adhering around the spray nozzles that spray the coating liquid is also a challenge in production.

[0008] The object of the present invention is to provide a powder coating apparatus and that can improve the dispersibility of powders and the efficiency of the coating process. Powder dispersion equipment The objective is to provide. [Means for solving the problem]

[0009] This describes the modes for carrying out the invention. The powder coating apparatus includes a dispersion section that uses a high-pressure fluid airflow to disperse a mixture of raw material powder and a coating liquid containing a coating material, while attaching a film of the coating liquid to the surface of the raw material powder; a conveying section that transports the raw material powder with the coating liquid film attached, carried by the airflow, and dries the coating liquid during transport; and a collection section that collects the composite powder generated by the drying of the coating liquid in the conveying section.

[0010] In this configuration, in the dispersion section, the mixture of raw material powder and coating liquid is dispersed by a high-pressure fluid airflow, such as supersonic air, into a powder where a film of the coating liquid adheres to the surface of the raw material powder. Therefore, powder aggregation can be suppressed and dispersibility can be improved. This allows the coating process to be carried out in a continuous process. Furthermore, since the dispersion section does not have a spray nozzle for injecting the coating liquid, there is no recovery loss due to powder adhering around the spray nozzle, and the efficiency of the coating process (powder recovery efficiency) can be improved.

[0011] Furthermore, by introducing the mixed material into the dispersion section in slurry form, the adhesion rate of the coating material to the main raw material particles can be increased.

[0012] It is preferable that the high-pressure fluid is preheated to a predetermined temperature.

[0013] This configuration suppresses the temperature drop caused by adiabatic expansion when the high-pressure fluid is injected, allowing for efficient drying without reducing the drying speed.

[0014] The dispersion unit may be configured to include a flow path through which the mixed material flows, and a first nozzle and a second nozzle that respectively blow out a stream of high-pressure fluid toward the impact point.

[0015] With this configuration, as the mixed material flowing through the channel passes through the collision point, it receives a shear force from the airflow colliding with it at the collision point, thereby enabling good dispersion of the mixed material into powder.

[0016] The airflow from the first and second nozzles preferably has a maximum Mach number of 1 or greater. In other words, the flow velocity of the airflow from the first and second nozzles preferably is greater than or equal to the speed of sound.

[0017] This allows for the application of a large shear force to the mixture through a supersonic airflow, effectively suppressing powder aggregation and further improving dispersibility.

[0018] The flow path, the first injection port, and the second injection port are formed such that the flow of the admixture toward the collision position and the center lines of the airflows from the first injection port and the second injection port are located in the same plane, and a plurality of the flow paths may be arranged side by side in a direction orthogonal to each center line.

[0019] Thereby, the throughput per unit time in the coating apparatus can be increased.

[0020] Further, the dispersion part may have a configuration including a flow path, an air flow inlet for introducing an air flow of high-pressure fluid into the flow path, and an admixture inlet provided on the downstream side in the flow direction of the air flow from the air flow inlet for introducing the admixture into the flow path.

[0021] According to this configuration, the admixture can be satisfactorily dispersed into powder by the admixture receiving a shearing force from the air flow in the flow path.

[0022] Further, in this configuration, the flow path may be in the form of a Laval nozzle in which a middle part extending downstream in the flow direction from the air flow inlet narrows.

[0023] In this configuration, the air flow introduced into the flow path from the air flow inlet can be accelerated by passing through the narrowed middle part.

[0024] The admixture inlet is preferably provided at a position on the downstream side in the flow direction from the narrowed middle part in the flow path.

[0025] Thereby, a large shearing force can be applied to the admixture from the air flow.

[0026] Preferably, the maximum Mach number of the air flow when passing through the admixture inlet is 1 or more. In other words, the flow velocity of the air flow when passing through the admixture inlet is preferably equal to or higher than the speed of sound.

[0027] This allows for the application of a large shear force to the mixture through a supersonic airflow, effectively suppressing powder aggregation and further improving dispersibility.

[0028] The coating apparatus may further include a gas introduction section for introducing a heated drying gas into the conveying section. The temperature of the heated drying gas is in the range of room temperature to 300°C, may be in the range of 40°C to 300°C, and is preferably in the range of 60°C to 200°C depending on the temperature characteristics of the solvent of the coating material.

[0029] This allows for faster drying of the coating liquid in the transport section.

[0030] The conveying section may have a cylindrical inner surface, and the gas introduction section may be configured to introduce heated drying gas into the conveying section so that the heated drying gas flows along the inner surface.

[0031] This configuration suppresses the adhesion of powder to the inner surface of the conveying section, further improving the efficiency of powder recovery.

[0032] The conveying section may be equipped with an introduction passage for introducing powder from the dispersion section, and the gas introduction section may be configured to introduce heated drying gas into the conveying section from a position opposite the pipe wall forming the introduction passage.

[0033] This configuration suppresses collisions between the powder flow introduced from the dispersion section to the conveying section and the heated drying gas introduced from the gas introduction section to the conveying section from directions perpendicular to each other, thereby suppressing the generation of turbulence within the conveying section. As a result, powder adhesion around the gas introduction section on the inner surface of the conveying section can be suppressed, further improving the powder recovery efficiency.

[0034] It is preferable that the dispersion unit, conveying unit, and collection unit are arranged in a straight line.

[0035] This allows for rapid transport of the powder, thereby increasing the speed of the coating process.

[0036] The dispersion section may be configured such that the mixed material flows vertically toward the conveying section.

[0037] This configuration allows the force of gravity acting on the mixture to be used for its flow, thereby reducing the energy required to pump the mixture. Furthermore, it prevents the mixture from becoming unevenly distributed in the direction of gravity, ensuring even distribution.

[0038] This describes the modes for carrying out the invention. The powder coating method involves using a high-pressure fluid airflow to disperse a mixture of raw material powder and a coating liquid containing a coating material, while attaching a film of the coating liquid to the surface of the raw material powder. The raw material powder with the coating liquid film attached is then transported by the airflow, the coating liquid dries during transport, and the composite powder generated by the drying of the coating liquid is collected.

[0039] This method can produce effects similar to those of the coating device described above.

[0040] This describes the modes for carrying out the invention. The powder dispersion apparatus comprises a flow path through which a slurry prepared by pre-mixing raw material powder and a coating liquid containing a coating material flows, and an injection nozzle that blows a stream of high-pressure fluid toward the collision point. As the slurry flows through the flow path and passes the collision point, a shear force is applied to the slurry by the airflow, thereby dispersing the slurry onto the raw material powder on which a film of coating liquid adheres to the surface.

[0041] This configuration allows for good dispersion of the raw material powder and coating liquid slurry onto the raw material powder, with the coating liquid film adhering to the surface, due to shear forces from an airflow such as supersonic air. This suppresses powder aggregation and improves dispersibility. Furthermore, since the dispersion unit does not have a spray nozzle for injecting the coating liquid, there is no recovery loss due to powder adhering around the spray nozzle, improving the efficiency of the coating process (powder recovery efficiency). In addition, introducing the mixture in slurry form increases the adhesion rate of the coating material to the main raw material particles.

[0042] The powder dispersion method corresponding to this powder dispersion apparatus involves pre-mixing raw material powder with a coating liquid containing a coating material to prepare a slurry, which is then circulated through a flow path. A high-pressure fluid airflow is blown from a nozzle towards the impact point, and as the slurry circulating through the flow path passes the impact point, a shear force is applied to the slurry by the airflow, thereby dispersing the slurry onto the raw material powder on which a coating liquid film adheres to the surface.

[0043] This method can produce effects similar to those of the corresponding powder dispersion device.

[0044] This describes the modes for carrying out the invention. The powder dispersion apparatus comprises a flow channel, an airflow inlet for introducing a high-pressure fluid airflow into the flow channel, and a slurry inlet located downstream of the airflow inlet in the direction of airflow flow, for introducing a slurry prepared by pre-mixing raw material powder and a coating liquid containing a coating material into the flow channel. By applying a shear force to the slurry by the airflow within the flow channel, the slurry is dispersed onto the raw material powder on which a coating liquid film adheres to the surface.

[0045] This configuration allows for good dispersion of the raw material powder and coating liquid slurry onto the raw material powder, with the coating liquid film adhering to the surface, due to shear forces from an airflow such as supersonic air. This suppresses powder aggregation and improves dispersibility. Furthermore, since the dispersion unit does not have a spray nozzle for injecting the coating liquid, there is no recovery loss due to powder adhering around the spray nozzle, improving the efficiency of the coating process (powder recovery efficiency). In addition, introducing the mixture in slurry form increases the adhesion rate of the coating material to the main raw material particles.

[0046] The powder dispersion method corresponding to this powder dispersion apparatus involves introducing a high-pressure fluid airflow into the flow path from an airflow inlet, introducing a slurry prepared by pre-mixing raw material powder and a coating liquid containing a coating material into the flow path from a slurry inlet located downstream of the airflow inlet in the direction of airflow, and dispersing the slurry onto the raw material powder on which a coating liquid film adheres to the surface by applying a shear force to the slurry within the flow path.

[0047] This method can produce effects similar to those of the corresponding powder dispersion device. [Effects of the Invention]

[0048] According to the present invention, the dispersibility of powders and the efficiency of coating processes can be improved. [Brief explanation of the drawing]

[0049] [Figure 1] This is a cross-sectional view illustrating the configuration of a coating apparatus according to the first embodiment of the present invention. [Figure 2] This is a top view of the dispersion mixing section. [Figure 3] This is a side view of the dispersion mixing section. [Figure 4] This is a cross-sectional view illustrating the configuration of a coating apparatus according to a second embodiment of the present invention. [Figure 5] This is a cross-sectional view illustrating the configuration of a coating apparatus according to a third embodiment of the present invention. [Figure 6] Figure 5 shows the dispersion mixing section viewed from below. [Figure 7] This is a cross-sectional diagram illustrating the configuration of a coating apparatus employing a classification unit. [Figure 8] This is a cross-sectional view illustrating the configuration of a coating apparatus according to a fourth embodiment of the present invention. [Figure 9] Figure 8 is an exploded perspective view of the dispersion mixing section. [Figure 10] This is a perspective view showing a modified example of the dispersion and mixing section. [Figure 11] This table shows the relationship between the number of units provided in the dispersion mixing section, the total injection volume, the amount of assist air, and the amount of air in the cylindrical section. [Figure 12] This is a perspective view showing other variations of the dispersion and mixing section. [Figure 13] Figure 12 shows an example of the cross-sectional shape of the slurry flow pipe in the dispersion mixing section. [Figure 14] Figure 12 shows another example of the cross-sectional shape of the slurry flow pipe in the dispersion mixing section. [Modes for carrying out the invention]

[0050] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0051] <First Embodiment> Figure 1 is a cross-sectional view illustrating the configuration of a coating apparatus 1 according to the first embodiment of the present invention.

[0052] The coating apparatus 1 is a device that performs a coating process to produce composite powder (particles) in which a coating layer is formed on the surface by bonding fine particles, which are the coating material, to the particles of the raw material powder. The coating apparatus 1 comprises a dispersion and mixing section 2, a conveying section 3, and a collection section 4. The dispersion and mixing section 2, the conveying section 3, and the collection section 4 are arranged in a straight line.

[0053] Figure 2 is a top view of the dispersion mixing unit 2. Figure 3 is a side view of the dispersion mixing unit 2. Below, the configuration of the dispersion mixing unit 2 will be described based on the state in which the dispersion mixing unit 2 is installed on a horizontal surface.

[0054] The dispersion mixing section 2 has a rectangular parallelepiped shape. A slurry inlet 11, a first airflow inlet 12, and a second airflow inlet 13 are formed on the upper surface of the dispersion mixing section 2. The slurry inlet 11, the first airflow inlet 12, and the second airflow inlet 13 are aligned in a straight line (hereinafter, the direction in which the slurry inlet 11, the first airflow inlet 12, and the second airflow inlet 13 are aligned is referred to as the "first horizontal direction"), and the first airflow inlet 12 and the second airflow inlet 13 are located on both sides of the slurry inlet 11 in the first horizontal direction. A powder flow outlet 14 is formed on one side of the dispersion mixing section 2 that extends in the first horizontal direction.

[0055] Inside the dispersion mixing section 2, a slurry flow path 15 is formed that connects the slurry inlet 11 and the powder flow outlet 14. The slurry flow path 15 extends downward from the slurry inlet 11, bends in a horizontal direction perpendicular to the first horizontal direction (hereinafter referred to as the "second horizontal direction"), and extends linearly toward the powder flow outlet 14. The portion of the slurry flow path 15 extending in the second horizontal direction has a narrow section 16 with a relatively small vertical dimension, a widening section 17 that is continuous with the narrow section 16 and whose vertical dimension increases as it approaches the powder flow outlet 14, and a wide section 18 that is continuous with the widening section 17 and whose vertical dimension is relatively large. The wide section 18 opens on the side of the dispersion mixing section 2, and this opening is formed as the powder flow outlet 14.

[0056] Furthermore, within the dispersion mixing section 2, a first flow path 21 that communicates with the first airflow inlet 12 and a second flow path 22 that communicates with the second airflow inlet 13 are formed.

[0057] The first flow path 21 extends downward from the first airflow inlet 12, bends horizontally, and extends toward the narrow section 16 of the slurry flow path 15. A first airflow nozzle 23 is formed on the side of the narrow section 16, and the first flow path 21 communicates with the first airflow nozzle 23. The first airflow nozzle 23 is formed as a slit-shaped opening whose vertical opening length is longer than its horizontal opening width, and the flow path cross-section of the first flow path 21 narrows as it approaches the first airflow nozzle 23.

[0058] The second flow path 22 is formed symmetrically with respect to the first flow path 21 with respect to a straight line that passes through the center of the slurry inlet 11 and extends in the second horizontal direction. Specifically, the second flow path 22 extends downward from the second airflow inlet 13, bends horizontally, and extends toward the narrow section 16 of the slurry flow path 15. A second airflow nozzle 24 is formed on the side of the narrow section 16, and the second flow path 22 is in communication with the second airflow nozzle 24. The second airflow nozzle 24 is formed as a slit-shaped opening whose vertical opening length is longer than its horizontal opening width, and the flow path cross-section of the second flow path 22 narrows as it approaches the second airflow nozzle 24.

[0059] One end of a slurry supply pipe 31 is connected to the slurry inlet 11. The other end of the slurry supply pipe 31 is connected to a slurry tank 32. The slurry tank 32 stores a mixture of raw material powder and a coating liquid containing the coating material in a slurry state.

[0060] In the following example, we will consider the case where coating apparatus 1 is used to produce positive electrode active material powder for all-solid-state batteries.

[0061] The raw material powder is a lithium metal composite oxide, with an average particle size of approximately 2-30 μm. The metal elements constituting the raw material powder include Co, Ni, Mn, Ti, Fe, and Al, but other elements may also be included to improve electrochemical properties. Specifically, the raw material powders include LiCoO2, LiNiO2, LiMn2O4, and LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, Li4Ti5O12 LiFePO4, LiNi 0.8 Co 0.15 Al 0.05 Examples of particles include O2.

[0062] The coating material is lithium niobate (LiNbO3), and the coating solution is an alkoxide solution that serves as a precursor to lithium niobate. In coating apparatus 1, the alkoxide solution is applied to the surface of the raw material powder particles, and the alkoxide solution is dried to produce powder in which the surface of the particles is coated with the precursor. Then, by calcining the precursor at a temperature of 250°C to less than 500°C, a composite powder, which is a positive electrode active material powder coated with a thin film of lithium niobate, can be obtained.

[0063] The coating material is not limited to lithium niobate; any lithium-ion conductive material with similar insulating properties and lithium composite oxides, such as lithium silicate, lithium borate, lithium titanate, lithium aluminate, lithium phosphate, or composite compounds thereof, is acceptable.

[0064] As alkoxides, in addition to ethoxides such as ethoxylithium, methoxides such as methoxylithium, propoxides such as various propoxylithium and butoxylithium, and butoxides can be used. As solvents, in addition to alcohols such as ethanol, methanol, various propanols, and butanol, organic solvents can be used depending on the purpose.

[0065] While organic solvents are preferable for the coating solution, aqueous solutions or mixed solvents of aqueous solutions and organic solvents can also be used by employing precursors that are highly stable in water. In addition to the sol-gel method, various methods can be used for precursor synthesis to form lithium-containing oxide thin films, such as methods utilizing water-soluble metal complexes like peroxyniobate complexes, polyol synthesis methods such as glycol modification, MOD (Metal Organic Decomposition) using organic acids, gelation methods using polysaccharides, LPD (Liquid Phase Deposition), and CSD (Chemical Solution Deposition).

[0066] Referring again to Figure 1, for example, slurry is supplied from the slurry tank 32 to the slurry inlet 11 through the slurry supply pipe 31 by the action of a pump or ejector (not shown). The slurry introduced from the slurry inlet 11 into the slurry flow path 15 flows through the slurry flow path 15 toward the powder flow outlet 14.

[0067] Meanwhile, high-pressure fluid is supplied to the first airflow inlet 12 and the second airflow inlet 13 through the first supply pipe 33 and the second supply pipe 34, respectively. The high-pressure fluid flows through the first channel 21 and the second channel 22 and is injected into the narrow section 16 of the slurry channel 15 from the first airflow nozzle 23 and the second airflow nozzle 24. The airflow injected from the first airflow nozzle 23 and the second airflow nozzle 24 is accelerated to a maximum speed of over the speed of sound, i.e., a maximum Mach number of 1 or more, and collides at a collision position P set within the narrow section 16. As the slurry passes through the collision position P, it receives a shear force from the airflow with a velocity exceeding the speed of sound that collides at the collision position P, and as a result, the slurry is dispersed into powder with a coating liquid attached to the surface of the particles. As the high-pressure fluid, inert gases such as nitrogen, carbon dioxide, and argon, or air in a high-pressure gas state can be used. The high-pressure fluid may also be supplied in a supercritical state. The maximum velocity of the ejected airflow is preferably between Mach 1 and 4, but it may be less than the speed of sound or greater than Mach 4.

[0068] The conveying section 3 includes a cylindrical section 41 having a cylindrical circumferential surface, a frustoconical section 42 that is continuous with the cylindrical section 41 and narrows as it moves away from the cylindrical section 41, and a tubular section 43 extending from the frustoconical section 42. The tubular section 43 may be a straight pipe, a spiral pipe, a cyclone pipe, or a combination thereof.

[0069] An assist air inlet 44 is formed on the circumferential surface of the cylindrical portion 41. Assist air is supplied to the assist air inlet 44 from an air supply source 45 through an assist air supply pipe 46. Examples of the air supply source 45 include a blower, pump, air compressor, and compressed gas cylinder. A mist separator (dryer) 47 for removing moisture from the air from the air supply source 45 and a heater 48 for heating the air from which moisture has been removed by the mist separator 47 are interposed in the middle of the assist air supply pipe 46. As a result, heated and dried air is introduced into the cylindrical portion 41 as assist air from the assist air inlet 44. The temperature of the heated and dried air is set within a temperature range of 60°C to 120°C, for example, when the solvent of the coating liquid is ethanol. Furthermore, since drying can be promoted by raising the temperature above the boiling point of the solvent, it is preferable that the temperature be 78°C or higher, which is the boiling point of ethanol. In addition to air, various gases such as nitrogen, carbon dioxide, and argon can be used as assist air. The temperature of the heated air can also be changed according to the solvent, and it is preferable that it be above the boiling point. However, it is not limited to the above range, and any temperature is acceptable as long as it can supply the amount of heat necessary for drying.

[0070] An airflow control member 51 is provided on the inner surface of the cylindrical section 41, facing the assist air inlet 44. The assist air introduced into the cylindrical section 41 from the assist air inlet 44 is transformed by the action of the airflow control member 51 into a swirling airflow that flows along the inner circumferential surface of the cylindrical section 41, passing through the cylindrical section 41, the frustoconical section 42, and the pipe section 43 in that order.

[0071] A powder inlet 52 is formed on the end face of the cylindrical portion 41. One end of a powder inlet passage 53 is connected to the powder inlet 52. The other end of the powder inlet passage 53 is connected to the powder flow outlet 14 of the dispersion mixing portion 2, and the powder flow outlet 14 and the powder inlet 52 are in communication via the powder inlet passage 53.

[0072] The powder generated in the dispersion and mixing section 2 is discharged from the powder flow outlet 14, flows through the powder inlet 53, and is introduced into the cylindrical section 41 of the conveying section 3 through the powder inlet 52. The powder introduced into the cylindrical section 41 is then transported by the airflow of assist air formed within the cylindrical section 41 towards the pipe section 43 of the conveying section 3. During this transport, the coating liquid adhering to the surface of the particles dries, generating powder in which the surface of the particles is coated with a precursor of the coating material. To promote drying, the conveying section 3 may be heated with a heater or the like.

[0073] The pipe section 43 of the conveying section 3 is connected to the collection section 4, and the inside of the conveying section 3 and the inside of the collection section 4 are in communication with each other. The airflow carrying the powder (powder flow) flowing through the conveying section 3 is introduced into the collection section 4. A bag filter 54 is provided inside the collection section 4. The powder flow introduced into the collection section 4 passes through the bag filter 54. As a result, the powder is captured by the bag filter 54, and only the airflow from which the powder has been removed passes through the bag filter 54.

[0074] Furthermore, the method of collecting powder by the collection unit 4 is not limited to using a bag filter 54; it may also be a cyclone method, or a combination of both. In addition, a blower 55 may be connected to the collection unit 4, and the function of the blower 55 may assist in the discharge of airflow from the collection unit 4.

[0075] <Effects and Effects> As described above, in the dispersion mixing unit 2, the slurry (mixture) formed by mixing the raw material powder and the coating liquid is dispersed onto the powder on which the coating liquid film adheres to the surface by the airflow of a high-pressure fluid. Therefore, aggregation of the raw material powder can be suppressed and dispersibility can be improved. As a result, the coating process on the powder can be carried out in a continuous process. Furthermore, since the dispersion mixing unit 2 is not equipped with a spray nozzle for spraying the coating liquid, there is no recovery loss due to powder adhering around the spray nozzle, and the efficiency of the coating process (powder recovery efficiency) can be improved.

[0076] Furthermore, by supplying the raw material powder and coating liquid to the dispersion mixing unit 2 in a slurry state, the adhesion rate of the coating material to the main raw material particles can be increased.

[0077] The dispersion and mixing unit 2 includes a slurry channel 15 through which the slurry flows, and a first airflow nozzle 23 and a second airflow nozzle 24, which blow out a stream of high-pressure fluid toward a collision position P set within the slurry channel 15. As the slurry flowing through the slurry channel 15 passes through the collision position P, it receives a shear force from the airflow colliding with it at the collision position P, thereby enabling good dispersion of the slurry into powder.

[0078] The conveying section 3 has an assist air inlet 44 for introducing assist gas, which is a heating and drying gas. By supplying assist gas to the conveying section 3, the powder can be efficiently conveyed toward the collection section 4 while simultaneously promoting the drying of the coating liquid in the conveying section 3.

[0079] The assist gas introduced into the conveying section 3 from the assist air inlet 44 is introduced so as to flow along the inner circumferential surface of the conveying section 3. This suppresses the adhesion of powder to the inner circumferential surface of the conveying section 3, further improving the powder recovery efficiency.

[0080] Furthermore, the dispersion and mixing unit 2, the conveying unit 3, and the collection unit 4 are arranged in a straight line. This allows for rapid conveyance of the powder, thereby increasing the speed of the coating process.

[0081] <Second Embodiment> Figure 4 is a schematic cross-sectional view illustrating the configuration of a coating apparatus 101 according to a second embodiment of the present invention. In Figure 4, parts corresponding to the parts shown in Figure 1 are denoted by the same reference numerals as those parts. Furthermore, the following description of the parts denoted by the same reference numerals will be omitted.

[0082] The coating apparatus 101 differs from the coating apparatus 1's coating apparatus 1 in the configuration of its conveying section 102. The conveying section 102 comprises a cylindrical body 103 and a circular tubular powder introduction passage 104 inserted through one end of the body 103. One end of the powder introduction passage 104 is open within the body 103 as a powder inlet 105. The other end of the powder introduction passage 104 is connected to the powder flow outlet 14 of the dispersion mixing section 2, and the powder flow outlet 14 and the powder inlet 105 are in communication via the powder introduction passage 104.

[0083] Furthermore, in the conveying section 102, the assist air inlet 44 faces the pipe wall of the powder introduction passage 104 and the main body 103 from the radial direction (a direction perpendicular to the centerline direction).

[0084] This configuration suppresses collisions between the flow of powder introduced from the dispersion mixing section 2 through the powder introduction path 104 into the conveying section 102 (main body 103) and the assist air introduced into the conveying section 102 from the assist air inlet 44, which are perpendicular to each other, thereby suppressing the generation of turbulence within the conveying section 102. As a result, it is possible to suppress the adhesion of powder around the assist air inlet 44 on the inner surface of the conveying section 102, further improving the powder recovery efficiency.

[0085] In addition, the same effects and advantages as those of the coating apparatus 1 shown in Figure 1 can be achieved by the configuration of the coating apparatus 101.

[0086] <Third Embodiment> Figure 5 is a schematic cross-sectional view illustrating the configuration of a coating apparatus 201 according to a third embodiment of the present invention. In Figure 5, parts corresponding to those shown in Figure 1 are denoted by the same reference numerals as those parts. Furthermore, the following description of the parts denoted by the same reference numerals will be omitted.

[0087] In the coating apparatus 201, a dispersion mixing unit 202 is used instead of the dispersion mixing unit 2.

[0088] Figure 6 is a view of the dispersion mixing section 202 from below.

[0089] The dispersion mixing section 202 is formed to be short in the first horizontal direction and long in the second horizontal direction. A flow path 203 extending in the second horizontal direction is formed within the dispersion mixing section 202. One end of the flow path 203 is open as a powder flow outlet 204 on the side of the dispersion mixing section 202 extending in the first horizontal direction. On the upper surface of the dispersion mixing section 202, there is an airflow inlet 205 for supplying a high-pressure fluid airflow into the flow path 203, and a slurry inlet 206 provided downstream of the airflow inlet 205 in the direction of airflow flow for introducing slurry into the flow path 203. In the flow path 203, between the airflow inlet 205 and the slurry inlet 206, a Laval nozzle 207 is formed by the contraction and expansion of the flow path cross-section.

[0090] As shown in Figure 5, a slurry supply pipe 31 extending from the slurry tank 32 is connected to the slurry inlet 206. The slurry supplied from the slurry tank 32 to the slurry inlet 206 through the slurry supply pipe 31 is introduced into the flow path 203 from the slurry inlet 206 and flows through the flow path 203 toward the powder flow outlet 204. Meanwhile, a supply pipe 208 is connected to the airflow inlet 205, and compressed gas (an example of a high-pressure fluid, such as an inert gas like nitrogen, carbon dioxide, or argon, or air in a high-pressure gas state) is supplied through this supply pipe 208. As the compressed gas passes through the Laval nozzle 207, its flow velocity increases significantly, reaching, for example, three times the speed of sound. As this airflow with a velocity exceeding the speed of sound overtakes the slurry introduced into the flow path 203, the slurry is subjected to shear force from the airflow and dispersed into powder particles on which the coating liquid adheres.

[0091] One end of the powder inlet 209 is connected to the powder flow outlet 204. The powder inlet 209 penetrates the end face of the cylindrical portion 41 of the conveying section 3, and the other end is located inside the cylindrical portion 41. The powder inlet 209 is formed such that the flow path cross-section gradually increases from one end to the other end (conveying section 3 side). The powder inlet 209 may be heated by a heater to promote the drying of the powder. For the same reason, the compressed gas supplied to the dispersion mixing section 202 may be heated by a heater 211. In this case, the temperature of the compressed gas should be set to be the same as the temperature of the heated drying air. It is also preferable that the temperature of the compressed gas be set higher than the boiling point of the solvent of the coating liquid. The powder generated in the dispersion mixing section 202 is discharged from the powder flow outlet 204, flows through the powder inlet 209, and is introduced into the cylindrical portion 41 of the conveying section 3. The powder introduced into the cylindrical section 41 is then transported by the airflow of assist air formed within the cylindrical section 41 towards the pipe section 43 via the transport section 3. During this transport, the coating liquid adhering to the surface of the particles dries, generating powder in which the surface of the particles is coated with a precursor. To promote the drying of the powder, the pipe section 43 of the transport section 3 may be heated by the heater 212.

[0092] The configuration of the coating apparatus 201 shown in Figure 5 can achieve the same effects and advantages as the configuration of the coating apparatus 1 shown in Figure 1.

[0093] Furthermore, by heating the compressed gas with the heater 211, the temperature drop due to adiabatic expansion when the compressed gas is injected is suppressed, allowing for efficient drying without reducing the drying speed.

[0094] <Classifier> Figure 7 is a schematic cross-sectional view illustrating the configuration of the coating apparatus 1 in which the classification unit 301 is employed. In Figure 7, parts corresponding to those shown in Figure 1 are given the same reference numerals. Furthermore, the following explanation of the parts with the same reference numerals will be omitted.

[0095] The aforementioned coating apparatus 1 may also employ a classification unit 301 to selectively collect composite powders on which a coating layer has been formed on the surface. The classification unit 301 consists of a classifier and is installed between the conveying unit 3 and the collection unit 4. The airflow (powder flow) carrying the powder flowing through the conveying unit 3 is introduced into the classification unit 301. The classification unit 301 then collects composite powders with relatively large particle sizes, while powders with relatively small particle sizes, such as precursors of coating materials that have not been compounded, pass through the classification unit 301 and flow into the collection unit 4, where they are collected.

[0096] In Figure 7, a cyclone is shown as the classification unit 301. However, the type of classifier used in the classification unit 301 should be appropriately determined according to the specific gravity and particle size of the powder to be collected in the classification unit 301. Furthermore, multiple classification units may be provided to perform multi-stage separation, allowing for separation into multiple stages according to particle size levels. For example, unwanted coarse particles, such as agglomerated powder, can be preemptively separated. Moreover, it goes without saying that classifiers may be used not only in the coating apparatus 1, but also in the aforementioned coating apparatuses 101 and 201.

[0097] <Fourth Embodiment> Figure 8 is a schematic cross-sectional view illustrating the configuration of a coating apparatus 401 according to a fourth embodiment of the present invention.

[0098] The coating apparatus 401 includes a dispersion and mixing section 402, a conveying section 403, a classification section 404, and a collection section 405.

[0099] Figure 9 is an exploded perspective view of the dispersion mixing unit 402. The dispersion mixing section 402 has a configuration in which a slurry flow pipe 411, a first airflow injection body 412, and a second airflow injection body 413 are sandwiched between two rectangular flat clamping plates 414.

[0100] The slurry flow tube 411 is a straight, cylindrical tube from which a slurry-like coating liquid is discharged. The slurry flow tube 411 is movable relative to the first airflow injection body 412 and the second airflow injection body 413 in the longitudinal direction. The tip opening of the slurry flow tube does not have to be a straight tube; for example, it may be formed in a substantially conical shape that narrows towards the tip opening. Chamfers, curved surfaces, or edges may be formed on the opening as appropriate.

[0101] The first airflow injector 412 and the second airflow injector 413 are positioned 180° symmetrically with respect to the centerline of the slurry flow pipe 411.

[0102] The first airflow injector 412 is formed in a rectangular plate shape with two corners on the slurry flow pipe 411 side cut off in a triangular shape. The lower part of the end face on the slurry flow pipe 411 side has an inclined surface 421 that slopes away from the slurry flow pipe 411 as it approaches the slurry flow pipe 411. A pressure boosting chamber 422 is formed in the first airflow injector 412, penetrating it in the thickness direction. The pressure boosting chamber 422 extends from the middle of the first airflow injector 412 in the direction opposite to the slurry flow pipe 411 toward the slurry flow pipe 411, bends diagonally downward, and slopes downward as it approaches the slurry flow pipe 411, extending toward the inclined surface 421. A slit-shaped first airflow nozzle 423 extending in the thickness direction is formed in the inclined surface 421, and the cross-sectional area of ​​the pressure boosting chamber 422 decreases as it approaches the inclined surface 421, connecting to the first airflow nozzle 423. Furthermore, a first airflow introduction passage 424 is formed in the first airflow injection body 412. One end of the first airflow introduction passage 424 is connected to the boost chamber 422, and the other end is open on the end face of the first airflow injection body 412 opposite to the slurry flow pipe 411 side.

[0103] The second airflow injector 413 is formed symmetrically with respect to the first airflow injector 412 with respect to the centerline of the slurry flow pipe 411. Specifically, the second airflow injector 413 is formed in a rectangular plate shape with two corners on the slurry flow pipe 411 side cut off in a triangular shape, and has an inclined surface 431 at the lower part of the end face on the slurry flow pipe 411 side, which slopes away from the slurry flow pipe 411 as it approaches the slurry flow pipe 411. In addition, a pressure boosting chamber 432 is formed through the second airflow injector 413 in the thickness direction. The pressure boosting chamber 432 extends from the middle of the second airflow injector 413 in the direction opposite to the slurry flow pipe 411 toward the slurry flow pipe 411, bends diagonally downward, and slopes so that it is located lower as it approaches the slurry flow pipe 411, extending toward the inclined surface 431. A slit-shaped second airflow nozzle 433 extending in the thickness direction is formed on the inclined surface 431, and the pressurizing chamber 432 has a decreasing cross-sectional area as it approaches the inclined surface 431 and is connected to the second airflow nozzle 433. In addition, a second airflow introduction passage 434 is formed on the second airflow injector 413. One end of the second airflow introduction passage 434 is connected to the pressurizing chamber 432, and the other end is open on the end face of the second airflow injector 413 opposite to the slurry flow pipe 411 side.

[0104] The two clamping plates 414 sandwich the slurry flow tube 411, the first airflow injection body 412, and the second airflow injection body 413 together between them. Both ends in the thickness direction of the pressure boosting chamber 422 of the first airflow injection body 412 are closed by the clamping plates 414. Similarly, both ends in the thickness direction of the pressure boosting chamber 432 of the second airflow injection body 413 are closed by the clamping plates 414.

[0105] As shown in Figure 8, one end of the slurry supply pipe 441 is connected to the upper end of the slurry flow pipe 411. The other end of the slurry supply pipe 441 is connected to the slurry tank 442. The slurry tank 442 stores a mixture of raw material powder and a coating liquid containing the coating material in a slurry state.

[0106] For example, a pump or ejector is used to supply slurry from the slurry tank 442 to the slurry flow pipe 411 through the slurry supply pipe 441. The slurry supplied to the slurry flow pipe 411 flows through the slurry flow pipe 411 and is discharged downward from the lower end of the slurry flow pipe 411.

[0107] Meanwhile, compressed gas (an example of a high-pressure fluid, such as inert gases like nitrogen, carbon dioxide, or argon, or air in a high-pressure gas state), is supplied to the first airflow inlet 424 and the second airflow inlet 434, respectively, through the first supply pipe 443 and the second supply pipe 444. The compressed gas flows through the first airflow inlet 424 and the second airflow inlet 434 and flows into the booster chambers 422 and 432, respectively. As a result, the air pressure in the booster chambers 422 and 432 increases, and airflow is forcefully ejected from the first airflow nozzle 423 and the second airflow nozzle 433. The airflow ejected from the first airflow nozzle 423 and the second airflow nozzle 433 collides at the collision position P below the slurry flow pipe 411. As the slurry discharged from the lower end of the slurry flow pipe 411 passes through the impact point P, it receives a shear force from the airflow impacting it at P, and is dispersed into the powder on which the coating liquid adheres to the surface of the particles. At this time, the discharge position of the slurry supply pipe 411 can be adjusted vertically, and can be finely adjusted to the position most suitable for dispersion relative to the impact point P.

[0108] The conveying section 403 integrally comprises a cylindrical section 451 having a cylindrical circumferential surface, a frustoconical section 452 that is continuous with the cylindrical section 451 and narrows as it moves away from the cylindrical section 451, and a tubular section 453 extending from the frustoconical section 452. The tubular section 453 may be a straight pipe, a spiral pipe, or a cyclone pipe. The conveying section 403 is positioned directly below the dispersion and mixing section 402, such that the centerline of the cylindrical section 451 extends in the vertical direction.

[0109] An assist air inlet 454 is formed on the circumferential surface of the cylindrical section 451. Assist air is supplied to the assist air inlet 454 from an air supply source 455 through an assist air supply pipe 456. Examples of the air supply source 455 include a blower, pump, air compressor, and compressed gas cylinder. A mist separator (dryer) 457, which removes moisture from the air from the air supply source 455, and a heater 458, which heats the air from which moisture has been removed by the mist separator 457, are interposed in the middle of the assist air supply pipe 456. As a result, heated and dry air is introduced into the cylindrical section 451 as assist air from the assist air inlet 454. In addition to atmospheric air, various gases such as nitrogen, carbon dioxide, and argon can be used as assist air.

[0110] The assist air inlet 454 and the assist air supply pipe 456 are formed so that assist air is blown out from the assist air inlet 454 in a tangential direction to the inner surface of the cylindrical section 451. Therefore, the assist air introduced into the cylindrical section 451 from the assist air inlet 454 becomes a swirling airflow that flows along the inner surface of the cylindrical section 451 and passes from the cylindrical section 451 to the frustoconical section 452 and then to the pipe section 453 in that order.

[0111] A powder inlet 459 is formed on the upper surface of the cylindrical section 451. The powder generated in the dispersion mixing section 402 is introduced into the cylindrical section 451 of the conveying section 403 through the powder inlet 459. The powder introduced into the cylindrical section 451 is then transported by the airflow of assist air formed inside the cylindrical section 451 towards the pipe section 453 of the conveying section 403. During this transport, the coating liquid adhering to the surface of the particles dries, generating powder in which the surface of the particles is coated with a precursor of the coating material. To promote the drying of the powder, the conveying section 403 may be heated by a heater 461. For the same reason, the compressed gas supplied to the first airflow inlet 424 and the second airflow inlet 434 of the dispersion mixing section 402 may be heated by a heater 462.

[0112] The classification unit 404 consists of a classifier and is located between the conveying unit 403 and the collection unit 405. The airflow (powder flow) carrying the powder flowing through the conveying unit 403 is introduced into the classification unit 404. The classification unit 404 then collects the composite powder with relatively large particle sizes, while the powder with relatively small particle sizes, such as a precursor for a coating material that does not contain raw material powder, passes through the classification unit 404 and flows into the collection unit 405.

[0113] A bag filter 463 is provided inside the collection unit 405. The powder flowing into the collection unit 405 is captured by the bag filter 463, and only the airflow from which the powder has been removed passes through the bag filter 463.

[0114] The configuration of the coating apparatus 401 shown in Figure 8 can achieve the same effects and advantages as the configuration of the coating apparatus 1 shown in Figure 1.

[0115] Furthermore, the configuration of the coating apparatus 401 allows for easy increase or decrease in the flow rate of the powder supplied from the dispersion mixing section 402 to the conveying section 403. Specifically, as shown in Figure 10, units U (modules) including a slurry flow pipe 411, a first airflow injection body 412, and a second airflow injection body 413 can be alternately stacked with clamping plates 414. By increasing or decreasing the number of these stacks, the number of units, which is the number of units U provided in the dispersion mixing section 402, can be increased or decreased, and the flow rate of the powder supplied from the dispersion mixing section 402 to the conveying section 403 can be increased or decreased according to the number of units. In the stack of units U and clamping plates 414, clamping plates 414 are provided at both ends.

[0116] As shown in Figure 11, it is preferable that the total flow rate (total injection amount) of the airflow injected from the first airflow nozzle 423 and the second airflow nozzle 433 be increased or decreased in proportion to the number of units. It is also preferable that the flow rate (assist air amount) of the assist air be increased or decreased in proportion to the number of units. In such a case, the flow rate (air amount) of air in the cylindrical portion 451 of the conveying section 403 will increase or decrease in proportion to the number of units.

[0117] Furthermore, as shown in Figure 12, even if there is only one unit U in the dispersion mixing section 402, the flow rate of the powder supplied from the dispersion mixing section 402 to the conveying section 403 can be increased by increasing the thickness of the unit U (slurry flow pipe 411, first airflow injection body 412, and second airflow injection body 413). In this case, in order to ensure uniformity of powder dispersion, the slurry flow pipe 411 may be formed with an elliptical cross-sectional shape, as shown in Figure 13, or multiple pipes with circular cross-sections may be formed, as shown in Figure 14.

[0118] <Variation> Although several embodiments of the present invention have been described above, the present invention can be implemented in yet other forms.

[0119] For example, in the dispersion mixing section 2, a slurry inlet 11 may be formed on the side surface, and a slurry flow path 15 connecting the slurry inlet 11 and the powder flow outlet 14 may extend in a straight line. The slurry flow pipe 411 does not have to be tubular, and the flow path may be formed integrally with other members of the dispersion mixing section 2.

[0120] Furthermore, the present invention is not limited to applications in the production of positive electrode active material powder for all-solid-state batteries, but may also be applied to manufacturing processes for food, pharmaceuticals, cosmetics, electronic components, and the like. Similarly, the particles targeted are not limited to those used in battery materials, and the average particle size may be other than 2 to 30 μm.

[0121] Furthermore, various design modifications can be made to the aforementioned configuration within the scope of the matters described in the patent claims. [Explanation of symbols]

[0122] 1,101,201,401: Coating equipment 2,202,402:Dispersion mixing section (dispersion section, powder dispersion device) 3,102: Conveying section 4,404: Collection Unit 11,206: Slurry inlet 12: First airflow inlet 13: Second airflow inlet 14: Powder flow outlet 15: Slurry channel (channel) 23,423: First airflow nozzle (first nozzle) 24,433: Second airflow nozzle (second nozzle) 44,454: Assist air inlet (gas inlet) 104: Powder introduction path 111: Flow channel 113: Airflow Inlet 114: Slurry inlet (mixture inlet) 411: Slurry flow pipe (flow channel) P: Collision position

Claims

1. A dispersion unit comprising: an airflow inlet for introducing a high-pressure fluid airflow; a slurry inlet provided downstream of the airflow inlet in the flow direction of the high-pressure fluid airflow for introducing a slurry obtained by mixing raw material powder and a coating liquid containing a coating material; and a dispersion unit that disperses the slurry introduced from the slurry inlet into the raw material powder on which a coating liquid film is attached to the surface by applying a shear force to the slurry introduced from the slurry inlet using the airflow of the high-pressure fluid airflow introduced from the airflow inlet; A powder coating apparatus comprising: an external supply of assist air; an introduction of the raw material powder with a coating liquid film attached from the dispersion unit; a conveying unit that carries the raw material powder with the coating liquid film attached on the airflow of the assist air and dries the coating liquid attached to the surface of the raw material powder during conveying.

2. A dispersion unit comprising an airflow inlet for introducing a high-pressure fluid airflow, and a slurry inlet for introducing a slurry obtained by mixing raw material powder and a coating liquid containing a coating material, wherein the slurry introduced from the slurry inlet is subjected to a shear force by the airflow of the high-pressure fluid introduced from the airflow inlet, thereby dispersing the slurry onto the raw material powder on which a film of the coating liquid adheres to the surface, The system includes a conveying unit to which assist air is supplied from the outside, the raw material powder with the coating liquid film attached is introduced from the dispersion unit, the raw material powder with the coating liquid film attached is transported on the airflow of the assist air, and the coating liquid attached to the surface of the raw material powder is dried during transport. A powder coating apparatus in which the position of the slurry inlet can be adjusted vertically.

3. The powder coating apparatus according to claim 2, wherein the slurry inlet is provided downstream of the airflow inlet in the direction of flow of the high-pressure fluid.

4. The powder coating apparatus according to any one of claims 1 to 3, further comprising a heater for heating the high-pressure fluid supplied to the airflow inlet.

5. The dispersion unit is provided with a first nozzle and a second nozzle as airflow inlets, which each blow out a stream of the high-pressure fluid toward the collision position, and further comprises a first flow path communicating with the first nozzle and through which the stream of the high-pressure fluid flows toward the first nozzle, and a second flow path communicating with the second nozzle and through which the stream of the high-pressure fluid flows toward the second nozzle, wherein the stream of the high-pressure fluid blown out from the first nozzle and the second nozzle collide with the slurry passing through the collision position, thereby applying a shear force to the slurry from the stream of the high-pressure fluid and dispersing the slurry onto the raw material powder on which a film of the coating liquid adheres to the surface, as described in any one of claims 1 to 4.

6. The powder coating apparatus according to claim 5, wherein the cross-sectional area of ​​the first flow path and the second flow path decreases as they approach the first injection port and the second injection port, respectively.

7. The powder coating apparatus according to claim 6, wherein the first nozzle and the second nozzle are each formed as slit-shaped openings extending parallel to each other.

8. The dispersion unit further comprises a slurry channel that communicates with the slurry inlet and through which the slurry flows toward the slurry inlet, The powder coating apparatus according to claim 7, wherein the slurry flow path, the first nozzle, and the second nozzle are formed such that the centerlines of the slurry flow toward the collision position, the airflow of the high-pressure fluid from the first nozzle, and the airflow of the high-pressure fluid from the second nozzle are located in the same plane.

9. The powder coating apparatus according to claim 8, wherein the slurry flow paths are arranged in a plurality of directions perpendicular to each center line.

10. The dispersion unit further comprises a flow path through which the slurry introduced from the slurry inlet flows, The powder coating apparatus according to claim 1, wherein the flow path has the form of a Laval nozzle that narrows in the middle section extending downstream from the airflow inlet in the flow direction.

11. The powder coating apparatus according to claim 10, wherein the slurry inlet is located downstream in the flow direction from the narrowed intermediate portion in the flow path.

12. The conveying section has a cylindrical inner circumferential surface, The powder coating apparatus according to any one of claims 1 to 11, further comprising an assist air introduction unit for introducing the assist air to the conveying unit so that the assist air flows along the inner circumferential surface.

13. The transport unit is equipped with an introduction path for introducing the raw material powder from the dispersion unit. The powder coating apparatus according to any one of claims 1 to 11, further comprising an assist air introduction section for introducing the assist air into the conveying section from a position opposite to the pipe wall forming the introduction passage.

14. The powder coating apparatus according to claim 12 or 13, further comprising a heater for heating the assist air supplied to the assist air introduction section.

15. The powder coating apparatus according to any one of claims 1 to 14, wherein the raw material powder is an electrode active material for a battery.

16. The powder coating apparatus according to any one of claims 1 to 15, wherein the dispersion unit is configured such that the slurry flows vertically toward the conveying unit.

17. A channel through which a slurry prepared by pre-mixing raw material powder and a coating liquid containing a coating material is supplied, A first nozzle and a second nozzle that blow out a stream of high-pressure fluid toward a collision position set within the flow path, It comprises a first flow path and a second flow path that communicate with the first injection port and the second injection port, respectively. A flow of the high-pressure fluid flows through the first and second flow channels toward the first and second injection ports, respectively. The cross-sectional area of ​​the first and second flow paths decreases as they approach the first and second injection ports, respectively. At the collision position, the airflow of the high-pressure fluid ejected from the first nozzle and the airflow of the high-pressure fluid ejected from the second nozzle collide. A powder dispersion apparatus that disperses the slurry onto the raw material powder on which a coating liquid film is attached to the surface by applying a shear force to the slurry from the airflow of the high-pressure fluid that collides with the slurry at the collision position as the slurry flows through the aforementioned flow path passes through the collision position.

18. The powder dispersion apparatus according to claim 17, wherein the first nozzle and the second nozzle are each formed as slit-shaped openings extending parallel to each other.

19. The powder dispersion apparatus according to claim 17 or 18, wherein the flow path, the first nozzle and the second nozzle are formed such that the centerlines of the slurry flow toward the impact position, the airflow of the high-pressure fluid from the first nozzle and the airflow of the high-pressure fluid from the second nozzle are located in the same plane.

20. Flow channels and An airflow inlet for introducing a high-pressure fluid airflow into the aforementioned flow path, The system includes a slurry inlet provided downstream of the airflow inlet in the direction of the flow of the high-pressure fluid, for introducing a slurry prepared by pre-mixing a raw material powder and a coating liquid containing a coating material into the flow path, The flow path has the form of a Laval nozzle, which narrows in the middle section extending downstream from the airflow inlet in the flow direction. A powder dispersion apparatus in which the slurry inlet is located downstream in the flow direction from the narrowed intermediate portion of the flow path.

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