Coating device and coating method

Abstract

To provide a coating device and a coating method that can effectively disperse an admixture onto coat-target particles attached with coating liquid in a film-like form, and suppress the re-agglomeration of the dispersed coat-target particles.SOLUTION: In a dispersion unit 11: slurry being an admixture composed of coat-target particles and a coating liquid in which a coating material is dissolved in a solvent flows from a slurry flow path 17 into a dispersion path 21; and dispersion gas heated by a dispersion gas heater 33 flows into the dispersion path 21 from a dispersion gas flow path 32. Then, the slurry is dispersed, through the airflow of the dispersion gas. onto the coat-target particles in each of which a surface thereof is attached with the coating liquid in a film-like form Since the dispersion gas is heated, as well as, the dispersion gas in a flow rate with a weight ratio of the dispersion gas to the weight of the coat-target particles is 3 or greater flows into the dispersion path 21, the slurry can be efficiently dispersed onto the coat-t target particles attached with the coating liquid in the film-like form.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a coating apparatus and a coating method for coating the surfaces of particles to be coated with a coating material. [Background technology]

[0002] In surface modification and composite technology, a coating material, which is a different fine particle, is bonded to the coated particle (parent particle) and the surface of the coated particle is coated with the coating material, thereby imparting various functions to the coated particle. This surface modification and composite technology is widely used in fields such as food, medicine, and cosmetics, and is also used to improve the electrical properties of materials used in electronic components and batteries.

[0003] For example, Patent Document 1 discloses an apparatus for producing a composite powder in which the surface of the coated particles is coated with a coating material. In this apparatus, the nozzle outlet is arranged facing the inside of a dryer. Compressed air is supplied to the nozzle by a compressor, and a mixture of the coated particles and a coating liquid in which the coating material is dissolved in a solvent is supplied. By supplying the compressed air and the mixture to the nozzle, the mixture in the form of droplets is sprayed from the nozzle into the dryer. Meanwhile, hot air is supplied into the dryer from a hot air inlet provided in the dryer. As a result, the mixture in the form of droplets is dried, and a powder in which the surface of the coated particles is coated with a precursor of the coating material is produced. Then, by firing the precursor of the coating material, a composite powder in which the surface of the coated particles is coated with a thin film of the coating material can be obtained. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-93865 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional devices, the particles to be coated have low dispersibility in the dryer, so that agglomerated particles are likely to occur. In addition, the dispersed particles to be coated may re-aggregate due to liquid bridging of the coating liquid adhering to the surface of the particles, resulting in the formation of granulated agglomerated particles.

[0006] An object of the present invention is to provide a coating apparatus and a coating method capable of satisfactorily dispersing a mixed material on coated particles having a coating liquid adhered thereto in the form of a film, and capable of suppressing reagglomeration of the dispersed coated particles. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a coating apparatus according to one aspect of the present invention includes a mixture flow path through which a mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent flows, a dispersion gas source for supplying a dispersion gas, a dispersion gas flow path through which the dispersion gas supplied from the dispersion gas source flows, a dispersion gas heating source for heating the dispersion gas flowing through the dispersion gas flow path, and a dispersion path to which the mixture flow path and the dispersion gas flow path are connected, the mixture flows from the mixture flow path into the dispersion path, and the dispersion gas heated by the dispersion gas heating source flows from the dispersion gas flow path into the dispersion path, and the mixture is dispersed onto the coated particles having the coating liquid adhered thereto in the form of a film by the airflow of the dispersion gas, and a control unit, and the control unit controls the dispersion gas source so that the ratio of the weight of the dispersion gas flowing into the dispersion path to the weight of the particles to be coated flowing into the dispersion path is 3 or more.

[0008] According to this configuration, in the dispersion section, a mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent flows from the mixture flow path into the dispersion path, and a dispersion gas heated by a dispersion gas heating source flows from the dispersion gas flow path into the dispersion path. Then, the mixture is dispersed into the particles to be coated having a film of coating liquid attached to the surface by the airflow of the dispersion gas. Since the dispersion gas is heated and the dispersion gas flows into the dispersion path at a flow rate such that the ratio of the weight of the dispersion gas to the weight of the particles to be coated is 3 or more, the mixture can be well dispersed into the particles to be coated having a film of coating liquid attached to the surface. In addition, since the dispersion gas is heated, it is possible to suppress the temperature drop due to adiabatic expansion when the dispersion gas flows from the dispersion gas flow path into the dispersion path, and the drying of the coating liquid can be promoted, so that the re-aggregation of the particles to be coated due to the liquid bridging of the coating liquid can be suppressed.

[0009] Therefore, by drying the coating liquid adhering to the surfaces of the particles to be coated, a powder having the surfaces of the particles to be coated with a precursor of the coating material with good dispersibility can be produced.

[0010] In addition, in a coating method corresponding to a coating apparatus according to one aspect of the present invention, a mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent is flowed from a mixture flow path into a dispersion path, a dispersion gas is sent from a dispersion gas source to a dispersion gas flow path connected to the dispersion path, the dispersion gas flowing through the dispersion gas flow path is heated by a dispersion gas heating source, and the mixture is dispersed onto the coated particles having the coating liquid adhering thereto in the form of a film by the airflow of the dispersion gas flowing from the dispersion gas flow path into the dispersion path, and the ratio of the weight of the dispersion gas flowing into the dispersion path to the weight of the particles to be coated flowing into the dispersion path is set to 3 or more.

[0011] This method can provide the same advantageous effects as those provided by the configuration of the coating apparatus according to one aspect of the present invention.

[0012] The temperature of the dispersion gas flowing into the dispersion passage is preferably equal to or higher than the boiling point of the solvent.

[0013] This allows the solvent to evaporate from the coating liquid attached to the surface of the coated particles, which in turn accelerates the drying of the coating liquid, thereby further suppressing re-aggregation of the coated particles due to liquid bridging of the coating liquid.

[0014] The heat quantity of the dispersion gas flowing into the dispersion path per unit time is preferably equal to or greater than the heat quantity required to evaporate the solvent from the mixture flowing into the dispersion path per unit time.

[0015] This also allows the solvent to evaporate from the coating liquid attached to the surface of the coated particles, which in turn accelerates the drying of the coating liquid, thereby further suppressing re-aggregation of the coated particles due to liquid bridging of the coating liquid.

[0016] A coating device according to another aspect of the present invention includes a mixture flow path through which a mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent flows, a dispersion gas source for delivering a dispersion gas, a dispersion gas flow path through which the dispersion gas delivered from the dispersion gas source flows, a dispersion gas heating source for heating the dispersion gas flowing through the dispersion gas flow path, and a dispersion path to which the mixture flow path and the dispersion gas flow path are connected, the mixture flows from the mixture flow path into the dispersion path, and the dispersion gas heated by the dispersion gas heating source flows from the dispersion gas flow path into the dispersion path, and the mixture is dispersed onto the particles to be coated having the coating liquid adhered thereto in the form of a film by the airflow of the dispersion gas, and a control unit, and the control unit controls at least one of the dispersion gas source and the dispersion gas heating source so that the heat quantity of the dispersion gas flowing into the dispersion path per unit time is equal to or greater than the heat quantity required to evaporate the solvent from the mixture flowing into the dispersion path per unit time.

[0017] According to this configuration, in the dispersion section, a mixture of coated particles and a coating liquid in which a coating material is dissolved in a solvent flows from the mixture flow path into the dispersion path, and a dispersion gas heated by a dispersion gas heating source flows from the dispersion gas flow path into the dispersion path. Then, the mixture is dispersed into the coated particles having the coating liquid attached to the surface in a film form by the airflow of the dispersion gas. Since the dispersion gas is heated and the heat amount of the dispersion gas flowing into the dispersion path per unit time is equal to or greater than the heat amount required to evaporate the solvent from the mixture flowing into the dispersion path per unit time, the drying of the coating liquid can be promoted, and re-aggregation of the coated particles due to liquid bridging of the coating liquid can be suppressed.

[0018] Therefore, by drying the coating liquid adhering to the surfaces of the particles to be coated, a powder having the surfaces of the particles to be coated with a precursor of the coating material with good dispersibility can be produced.

[0019] In a coating method corresponding to a coating apparatus according to another aspect of the present invention, a mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent is flowed from a mixture flow path into a dispersion path, a dispersion gas is sent from a dispersion gas source to a dispersion gas flow path connected to the dispersion path, the dispersion gas flowing through the dispersion gas flow path is heated by a dispersion gas heating source, the mixture is dispersed onto the particles to be coated having the coating liquid adhering thereto in the form of a film by the airflow of the dispersion gas flowing from the dispersion gas flow path into the dispersion path, and the heat quantity of the dispersion gas flowing into the dispersion path per unit time is set to be equal to or greater than the heat quantity required to evaporate the solvent from the mixture flowing into the dispersion path per unit time.

[0020] This method can provide the same advantageous effects as those provided by the configuration of the coating apparatus according to the other aspects of the present invention.

[0021] The pressure of the dispersion gas delivered by the dispersion gas source is preferably 0.15 MPa or more. Note that the pressure here is a gauge pressure, and atmospheric pressure is taken as 0 Pa.

[0022] This makes it easier to ensure that the ratio of the weight of the dispersion gas to the weight of the particles to be coated is 5 or more.

[0023] The mixture is preferably adjusted so that the solid-liquid ratio (weight of coating material:weight of solvent) is 2:0.5-3.

[0024] This can further suppress re-aggregation of the coated particles caused by liquid bridging of the coating liquid.

[0025] The particles to be coated may be particles having an average particle size in the range of 100 nm to 50 μm.

[0026] The coating apparatus may further include a drying section having a dry gas flow path through which a dry gas flows and a drying path to which the dry gas flow path is connected, and in which the coating liquid adhering to the particles to be coated flowing from the dispersion path into the drying path is dried by the dry gas flowing from the dry gas flow path into the drying path.

[0027] This configuration allows the coating liquid attached to the surface of the coated particles to be dried, and powder in which the surface of the coated particles is covered with a precursor of the coating material can be produced with good dispersibility. In addition, since the drying of the coating liquid is promoted in the dispersion section (dispersion path), the coating liquid can be dried well in the drying path. As a result, the powder (powder including the coated particles) flowing from the dispersion path into the drying path is prevented from adhering to the inner surface of the drying path, and the frequency of cleaning the inside of the drying path can be reduced.

[0028] The coating apparatus may further include a dry gas heating source that heats the dry gas flowing through the dry gas passage.

[0029] By heating the drying gas, the coating liquid adhering to the surfaces of the coated particles can be dried more effectively, and therefore, powder in which the surfaces of the coated particles are covered with the precursor of the coating material can be produced with better dispersibility. Effect of the Invention

[0030] According to the present invention, the mixed material can be well dispersed in the coated particles to which the coating liquid is attached in the form of a film, and the re-aggregation of the dispersed coated particles can be suppressed. As a result, by drying the coating liquid attached to the coated particles, a powder in which the surfaces of the coated particles are covered with a precursor of the coating material can be produced with good dispersibility. [Brief description of the drawings]

[0031] [Figure 1] 1 is a diagram illustrating a configuration of a coating apparatus according to a first embodiment of the present invention. FIG. [Diagram 2] FIG. 4 is a diagram illustrating the configuration of a coating apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0033] First Embodiment FIG. 1 is a diagram illustrating the configuration of a coating apparatus 1 according to a first embodiment of the present invention.

[0034] The coating apparatus 1 is an apparatus used in a coating process for producing a powder in which the surfaces of the particles to be coated (base particles) are coated with a precursor of a coating material, which is made of fine particles. The coating apparatus 1 includes a dispersion section 11, a dispersion gas supply section 12, a drying section 13, and a collection section 14.

[0035] The particles to be coated and the coating material are supplied to the dispersion section 11 in the form of a slurry (mixture) obtained by mixing the particles to be coated with a coating liquid in which the coating material is dissolved in a solvent. The dispersion section 11 has the configuration of a collision type high-speed air current dispersion unit. In the dispersion section 11 having the configuration of a collision type high-speed air current dispersion unit, multiple high-speed air currents collide at a collision position CP, and the slurry receives a shear force from the high-speed air currents at the collision position CP, dispersing the slurry into the particles to be coated with the coating liquid adhering to the surface in the form of a film.

[0036] Specifically, the slurry is prepared in a glove box that is isolated from the outside air. In preparing the slurry, the particles to be coated and the coating liquid are weighed out so that the slurry has a predetermined solid-liquid ratio, for example, a solid-liquid ratio in the range of 2:0.5 to 3. The slurry prepared to a predetermined solid-liquid ratio is stored in a slurry tank 15. In the slurry tank 15, the slurry is stirred by a stirring mechanism 16 such as a magnetic stirrer. One end of a slurry flow path 17 is connected to the slurry tank 15. A slurry pump 18 is installed in the middle of the slurry flow path 17.

[0037] The dispersion section 11 (high-velocity air current dispersion unit) includes a dispersion path 21. The dispersion path 21 includes a slurry inlet path 22 and dispersion gas inlet paths 23, 24. The slurry inlet path 22 extends linearly in the vertical direction. The dispersion gas inlet paths 23, 24 are provided separately on one side and the other side in a direction perpendicular to the vertical direction with respect to the slurry inlet path 22. The dispersion gas inlet paths 23, 24 are inclined at a predetermined angle (for example, 45°) with respect to the vertical direction so as to be positioned lower as they approach the collision position CP set in the slurry inlet path 22. The dispersion gas inlet paths 23, 24 communicate with the slurry inlet path 22, and the lower ends of the dispersion gas inlet paths 23, 24 on the collision position CP side are opened toward the collision position CP.

[0038] The other end of the slurry flow path 17 is connected to the upper end of the slurry inlet path 22. By the action of the slurry pump 18, the slurry is sucked from the slurry tank 15 into the slurry flow path 17, and the slurry flowing through the slurry flow path 17 flows into the slurry inlet path 22. The slurry that has flowed into the slurry inlet path 22 flows toward the lower end of the slurry inlet path 22.

[0039] The dispersion gas supply unit 12 includes a compressor 31 , a dispersion gas passage 32 , and a dispersion gas heater 33 .

[0040] The compressor 31 delivers air as the dispersion gas.

[0041] One end of the dispersion gas flow path 32 is connected to the compressor 31, and air sent out from the compressor 31 flows through the dispersion gas flow path 32. The other end of the dispersion gas flow path 32 branches into branch paths 34 and 35. The tip of the branch path 34 is connected to the upper end of the dispersion gas inlet path 23, and the tip of the branch path 35 is connected to the upper end of the dispersion gas inlet path 24.

[0042] The dispersion gas heater 33 is disposed at a position on the compressor 31 side of the branch point of the branch passages 34 and 35 in the dispersion gas passage 32 , and heats the air flowing through the dispersion gas passage 32 .

[0043] In addition, an on-off valve 36 and a mist separator (dryer) 37 are interposed in this order from the compressor 31 side in the middle of the dispersion gas flow path 32, between the compressor 31 and the dispersion gas heater 33. The on-off valve 36 opens and closes the dispersion gas flow path 32, and switches between allowing and blocking the flow of air in the dispersion gas flow path 32. The mist separator 37 removes moisture from the air flowing through the dispersion gas flow path 32.

[0044] With the on-off valve 36 open, the air sent out from the compressor 31 flows through the dispersion gas flow passage 32 toward the dispersion gas inlet passages 23, 24. While the air flows through the dispersion gas flow passage 32, moisture is removed from the air by the mist separator 37, and the air is heated by the dispersion gas heater 33. As a result, the air flowing through the dispersion gas flow passage 32 becomes dehumidified and heated dry heated air, and the dry heated air flows from the dispersion gas flow passage 32 (branch passages 34, 35) into the dispersion gas inlet passages 23, 24. While the dry heated air flows through the dispersion gas inlet passages 23, 24, the flow velocity of the dry heated air increases significantly, and for example, the flow velocity of the dry heated air reaches or exceeds the speed of sound.

[0045] As a result, high-velocity air currents of dry heated air are ejected from the lower ends of the dispersion gas inflow channels 23, 24 toward the collision position CP, and these high-velocity air currents collide at the collision position CP. The slurry flowing toward the lower end of the slurry inflow channel 22 is dispersed into the coated particles having the coating liquid adhered to their surfaces in the form of a film by the shear force received from the high-velocity air currents at the collision position CP.

[0046] As the dispersion gas, various gases such as nitrogen, carbon dioxide, and inert gases can be used in addition to air.

[0047] The drying section 13 includes a drying container 41. The drying container 41 integrally includes a cylindrical section 42 having a cylindrical peripheral surface, and a conical section 43 that is continuous with the cylindrical section 42 and has a generally conical shape that narrows as it moves away from the cylindrical section 42. The drying container 41 is disposed directly below the dispersion section 11 such that the center line of the cylindrical section 42 extends in the vertical direction. A drying gas inlet 44 is provided on the peripheral surface of the cylindrical section 42. One end of a drying gas flow path 45 is connected to the drying gas inlet 44. The other end of the drying gas flow path 45 is connected to an intake filter 46. A drying gas heater 47 passes through the middle of the drying gas flow path 45.

[0048] The collecting section 14 includes a collecting cyclone 51 and a collecting filter 52. One end of an intake pipe 53 is connected to the collecting cyclone 51. The other end of the intake pipe 53 is connected to a suction port of a drying blower 54. The collecting cyclone 51 is also provided with a powder introduction section 55. One end of a sanitary pipe 56 is connected to the powder introduction section 55. The other end of the sanitary pipe 56 is connected to the lower end of the drying container 41. The collecting filter 52 is disposed in the middle of the intake pipe 53.

[0049] When the drying blower 54 is operated, the air in the collecting cyclone 51 is sucked into the intake pipe 53, and the inside of the collecting cyclone 51 becomes negative pressure. When the inside of the collecting cyclone 51 becomes negative pressure, the inside of the drying container 41 becomes negative pressure via the sanitary pipe 56. Due to the negative pressure in the drying container 41, air (atmospheric air) is sucked into the drying gas flow path 45 through the intake filter 46, and the air flows as dry gas through the drying gas flow path 45 toward the drying container 41. While the air flows through the dry gas flow path 45, the air is heated by the dry gas heater 47. As a result, the air flowing through the dry gas flow path 45 becomes heated air, and the heated air flows from the dry gas flow path 45 through the dry gas inlet part 44 into the drying container 41.

[0050] The drying gas inlet 44 and the drying gas flow path 45 are formed so that the heated air is blown out from the drying gas inlet 44 in the tangential direction of the inner circumferential surface of the cylindrical portion 42 of the drying container 41. Therefore, the heated air introduced from the drying gas inlet 44 into the drying container 41 becomes a vortex air current that flows along the inner circumferential surface of the cylindrical portion 42.

[0051] On the other hand, the inside of the drying container 41 communicates with the slurry inlet 22 of the dispersion section 11 as a drying path. As a result, the coated particles having the coating liquid attached to their surfaces in a film form flow into the drying container 41 from the slurry inlet 22. The powder including the coated particles is carried inside the drying container 41 from the cylindrical section 42 to the conical section 43 by the vortex air current of the heated air generated in the drying container 41. During this transport, the coating liquid attached to the surface of each coated particle dries, thereby generating a powder in which the surface of each coated particle is covered with a precursor of the coating material (hereinafter, this powder is referred to as "dry gel powder"). In addition, the droplets of the coating liquid that are not attached to the surface of the coated particle dry, generating dried pieces of the coating liquid.

[0052] The dry gel powder and dried pieces of coating liquid that reach the bottom end of the drying container 41 flow through the sanitary pipe 56 due to the negative pressure in the collecting cyclone 51 and are sucked into the collecting cyclone 51. In the collecting cyclone 51, the airflow containing the dry gel powder and dried pieces of the coating liquid swirls, and the dry gel powder with a relatively large particle size and mass is separated from the dried pieces of the coating liquid with a relatively small particle size and mass due to the centrifugal force and gravity. The dry gel powder is stored in a collecting box 57 connected to the bottom end of the collecting cyclone 51.

[0053] The dried pieces of the coating liquid separated in the collecting cyclone 51 are sucked into the intake pipe 53 by the air and are captured by the collecting filter 52. Therefore, the collecting filter 52 allows only air to pass through.

[0054] As the drying gas, various gases such as nitrogen, carbon dioxide, and inert gases can be used in addition to air.

[0055] The coating apparatus 1 also includes a control unit 61. The control unit 61 includes a microcomputer (microcontroller). The microcomputer includes a CPU and a memory. The memory includes, for example, a non-volatile memory such as a flash memory or an E2PROM that allows data to be rewritten, and a volatile memory such as a dynamic random access memory (DRAM). The non-volatile memory stores programs for controlling each part of the coating apparatus 1. The CPU executes the programs stored in the non-volatile memory, and uses the volatile memory as a work area when executing the programs. The memory also stores various data necessary for controlling each part.

[0056] The details of the control of each part by the control unit 61 will be described later.

[0057] When the coating apparatus 1 is used to produce a positive electrode active material powder for an all-solid-state battery, the particles to be coated are, for example, lithium metal composite oxide particles having an average particle size of about 2 to 30 μm. Metal elements constituting the powder include Co, Ni, Mn, Ti, Fe, Al, etc., but other elements may also be included to improve electrochemical properties. Specifically, particles constituting the powder include LiCoO2, LiNiO2, LiMn2O4, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, Li4Ti5O 12 , LiFePO4, LiNi 0.8 Co 0.15 Al 0.05 Examples of particles include O2.

[0058] For example, when the coating material bonded to the coated particles is lithium niobate (LiNbO3), the coating liquid can be an alkoxide solution of lithium and niobium, using ethoxylithium (LiOC2H5) as the lithium source, pentaethoxyniobium (Nb(OC2H5)5) as the niobium source, and ethanol as the solvent. When the coating solution is an alkoxide solution of lithium and niobium, the dry gel powder collected in the collection unit 14 of the coating device 1 can be baked at 250°C or higher and lower than 500°C to obtain a positive electrode active material powder in which the coated particles are covered with a lithium niobate thin film.

[0059] <Second embodiment> Fig. 2 is a diagram illustrating the configuration of a coating apparatus 101 according to a second embodiment of the present invention. In Fig. 2, parts corresponding to those shown in Fig. 1 are given the same reference numerals as those parts. In the following, the description of the parts given the same reference numerals will be omitted.

[0060] The coating apparatus 101 includes a dispersion section 111. In the coating apparatus 1 shown in Fig. 1, the dispersion section 111 has the configuration of a collision type high-speed air current dispersion unit, whereas the dispersion section 111 has the configuration of a Laval type high-speed air current dispersion unit. In the dispersion section 111 having the configuration of a Laval type high-speed air current dispersion unit, a high-speed air current having a flow velocity exceeding the speed of sound flows past the slurry, so that the slurry receives a shear force from the high-speed air current, and the slurry is dispersed into the coated particles having the coating liquid attached to the surface in the form of a film.

[0061] Specifically, in the coating apparatus 101, the drying container 41 of the drying section 13 is disposed so that the center line of the drying container 41 extends in a direction perpendicular to the up-down direction. Also, the other end of the dispersion gas flow path 32, i.e., the end opposite to the end of the dispersion gas flow path 32 connected to the compressor 31, is not branched.

[0062] The dispersion section 111 includes a dispersion path 121. The dispersion path 121 extends in the same direction as the center line of the drying container 41. One end of the dispersion path 121 is connected to the end face of the drying container 41 opposite to the cone portion 43 side, and the dispersion path 121 communicates with the inside of the drying container 41 as a drying path. The other end of the dispersion gas flow path 32 is connected to the other end of the dispersion path 121. In addition, the other end of the slurry flow path 17, that is, the end of the slurry flow path 17 opposite to the end connected to the slurry tank 15, is connected to the dispersion path 121 at a position closer to the drying container 41 side than the connection position of the dispersion gas flow path 32. In addition, in the dispersion path 121, a cross section of the flow path contracts and expands in the middle part between the connection position of the dispersion gas flow path 32 and the connection position of the slurry flow path 17, forming a Laval nozzle.

[0063] The slurry flowing from the slurry passage 17 into the dispersion passage 121 flows through the dispersion passage 121 toward the drying vessel 41. On the other hand, the high-speed airflow of the dry heated air flowing from the dispersion gas passage 32 into the dispersion passage 121 increases in flow velocity significantly by passing through the Laval nozzle, and the flow velocity can reach, for example, three times the speed of sound. As the airflow with a flow velocity exceeding the speed of sound flows past the slurry flowing through the dispersion passage 121, the slurry is subjected to a shear force from the high-speed airflow, and is dispersed into the coated particles having the coating liquid attached to their surfaces in the form of a film.

[0064] <Control content> The control unit 61 controls the operation of the compressor 31 so that the ratio of the weight of the dry heated air flowing into the dispersion path 21, 121 to the weight of the particles to be coated flowing into the dispersion path 21, 121 is 3 or more, preferably in the range of 8 or more and 100 or less.

[0065] Furthermore, the control unit 61 controls the operation of at least one of the compressor 31 and the dispersion gas heater 33 so that the temperature of the dry heated air flowing into the dispersion paths 21, 121 becomes equal to or higher than the boiling point of the solvent contained in the coating liquid.

[0066] When the pressure of the air sent out from the compressor 31 is a predetermined value A and the output of the dispersion gas heater 33 is a predetermined value B, the temperature of the dry heated air flowing into the dispersion path 21, 121 becomes a predetermined temperature equal to or higher than the boiling point of the solvent. In this case, if the pressure of the air sent out from the compressor 31 is lowered from the predetermined value A, the flow rate of the air flowing through the dispersion gas path 32 decreases, and the amount of heat imparted from the dispersion gas heater 33 to the air flowing through the dispersion gas path 32 per unit time increases. Therefore, the control unit 61 may lower the output of the dispersion gas heater 33 from the predetermined value B within a range in which the temperature of the dry heated air flowing into the dispersion path 21, 121 is maintained at or higher than the boiling point of the solvent. On the other hand, if the pressure of the air sent out from the compressor 31 is increased from the predetermined value A, the flow rate of the air flowing through the dispersion gas path 32 increases, and the amount of heat imparted from the dispersion gas heater 33 to the air flowing through the dispersion gas path 32 per unit time decreases. Therefore, the control unit 61 may increase the output of the dispersion gas heater 33 from the predetermined value B so that the temperature of the dry heated air flowing into the dispersion paths 21, 121 is maintained at or above the boiling point of the solvent.

[0067] However, the ratio of the weight of the dry heated air flowing into the dispersion path 21, 121 to the weight of the particles to be coated flowing into the dispersion path 21, 121 must be kept at 5 or more. That is, the control unit 61 can control the operation of the compressor 31 and the dispersion gas heater 33 to increase or decrease the pressure of the air sent out from the compressor 31 and increase or decrease the output of the dispersion gas heater 33 within a range in which the ratio of the weight of the dry heated air as dispersion gas flowing into the dispersion path 21, 121 to the weight of the particles to be coated flowing into the dispersion path 21, 121 is kept at 5 or more and the temperature of the dry heated air flowing into the dispersion path 21, 121 is kept at or above the boiling point of the solvent.

[0068] In addition, the control unit 61 controls the operation of at least one of the compressor 31 and the dispersion gas heater 33 so that the heat quantity of the dry heated air flowing into the dispersion path 21, 121 per unit time as a dispersion gas is equal to or greater than the heat quantity required to evaporate the solvent from the coating liquid flowing into the dispersion path 21, 121 per unit time, and preferably, so that the heat quantity of the dry heated air flowing into the dispersion path 21, 121 per unit time as a dispersion gas is within the range of 1.1 to 3 times the heat quantity required to evaporate the solvent from the coating liquid flowing into the dispersion path 21, 121 per unit time.

[0069] The control unit 61 controls the operation of the compressor 31 so that the pressure of the air discharged by the compressor 31 is 0.15 MPa or more, preferably 0.2 to 0.7 MPa, in order to ensure that the ratio of the weight of the dry heated air flowing into the dispersion path 21, 121 to the weight of the particles to be coated flowing into the dispersion path 21, 121 is 5 or more.

[0070] In the above embodiment, the compressor 31 is used as the dispersion gas source for sending out the dispersion gas. However, the dispersion gas source is not limited to the compressor 31 and may be any source that can send out dispersion gas at a pressure of 0.15 MPa or more to the dispersion gas flow path 32.

[0071] <Action and effect> As described above, in the dispersion section 11, 111, the slurry, which is a mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent, flows from the slurry flow path 17 into the dispersion path 21, 121, and the dispersion gas heated by the dispersion gas heater 33 flows from the dispersion gas flow path 32 into the dispersion path 21, 121. Then, the slurry is dispersed into the particles to be coated having the coating liquid attached to the surface in a film form by the airflow of the dispersion gas. Since the dispersion gas is heated and the dispersion gas flows into the dispersion path 21, 121 at a flow rate such that the ratio of the weight of the dispersion gas to the weight of the particles to be coated is 3 or more, the slurry can be well dispersed into the particles to be coated having the coating liquid attached to the surface in a film form. In addition, since the dispersion gas is heated, it is possible to suppress the temperature drop due to adiabatic expansion when the dispersion gas flows from the dispersion gas flow path 32 into the dispersion path 21, 121, and the drying of the coating liquid can be promoted, so that the re-aggregation of the particles to be coated due to the liquid bridging of the coating liquid can be suppressed.

[0072] Therefore, by drying the coating liquid adhering to the particles to be coated, a powder having the surfaces of the particles to be coated covered with a precursor of the coating material with good dispersibility can be produced.

[0073] The temperature of the dispersion gas flowing into the dispersion passage 21, 121 is preferably equal to or higher than the boiling point of the solvent. This allows the solvent to evaporate from the coating liquid adhering to the surface of the coated particles. As a result, the drying of the coating liquid can be further promoted, and the re-agglomeration of the coated particles due to liquid bridging of the coating liquid can be further suppressed.

[0074] The heat quantity of the dispersion gas flowing into the dispersion path 21, 121 per unit time is preferably equal to or greater than the heat quantity required to evaporate the solvent from the slurry flowing into the dispersion path 21, 121 per unit time. This also allows the solvent to evaporate from the coating liquid adhering to the surface of the coated particles. As a result, the drying of the coating liquid can be further promoted, and re-agglomeration of the coated particles due to liquid bridging of the coating liquid can be further suppressed.

[0075] When the heat quantity of the dispersion gas flowing into the dispersion path 21, 121 per unit time is equal to or greater than the heat quantity required to evaporate the solvent from the slurry flowing into the dispersion path 21, 121 per unit time, the ratio of the weight of the dry heated air flowing into the dispersion path 21, 121 to the weight of the particles to be coated flowing into the dispersion path 21, 121 does not necessarily have to be kept at 3 or more, but it is preferable to keep it at 3 or more. By keeping the ratio at 3 or more, the slurry can be well dispersed on the particles to be coated having the coating liquid attached to the surface in the form of a film.

[0076] The pressure of the dispersion gas (air) delivered by the compressor 31 is preferably 0.15 MPa or more, which makes it easier to ensure that the ratio of the weight of the dispersion gas to the weight of the particles to be coated is 3 or more.

[0077] The slurry is preferably adjusted so that the solid-liquid ratio is 2:0.5 to 3. This can further suppress re-aggregation of the coated particles caused by liquid bridging of the coating liquid.

[0078] The coating device 1 includes a drying section 13. Heated air is supplied from a drying gas passage 45 through a drying gas inlet 44 into a drying container 41 of the drying section 13, and powder containing particles to be coated with a coating liquid attached to the surface in a film form flows in from the dispersion section 11. The powder is transported by the air flow of the heated air, and the coating liquid attached to the surface of the particles to be coated dries during the transport. Since the drying of the coating liquid is promoted in the dispersion section 11, the coating liquid can be satisfactorily dried in the drying section 13. As a result, the powder flowing from the dispersion section 11 into the drying section 13 is prevented from adhering to the inner surface of the drying container 41, and the frequency of cleaning the inside of the drying container 41 can be reduced.

[0079] <Modification> Although two embodiments of the present invention have been described above, the present invention can be embodied in further other forms.

[0080] For example, the present invention is not limited to application in the production of positive electrode active material powder for all-solid-state batteries, but may also be applied to the manufacturing processes of foods, medicines, cosmetics, electronic components, etc. In such cases, the particles to be coated may be particles having an average particle size in the range of 100 nm or more and 50 μm or less.

[0081] In addition, various design modifications can be made to the above-described configuration within the scope of the claims. EXAMPLES

[0082] Next, a more specific embodiment will be described, but the present invention is not limited to this embodiment.

[0083] <Adjustment of coating solution> 142.96g of ammonia water with a concentration of 28% by mass and 848.49g of ion-exchanged water were mixed, and the diluted ammonia water was cooled. Meanwhile, in a container, 848.72g of ion-exchanged water and 17.97g of lithium hydroxide monohydrate (LiOH·H2O) were added to 1070.62g of hydrogen peroxide water with a concentration of 30% by mass, and the mixture was stirred to dissolve the lithium hydroxide monohydrate. Then, 71.24g of niobic acid (Nb2O5·4.09H2O (Nb2O5 purity 78.3%)) was added to the solution in the container, and diluted ammonia water was further added to the container, and the solution was thoroughly stirred while cooling the container, to obtain a transparent coating solution. In the following Examples 1 to 3 and Comparative Example, the coating solution prepared in this manner was used.

[0084] <Example 1> 50 g of the coating solution was placed in a 300 ml container, and while stirring using a magnetic stirrer, 100 g of lithium cobalt oxide (LiCoO2) with an average particle size of 5 μm was added as particles to be coated (positive electrode active material), and the mixture was stirred for several minutes to obtain a slurry.

[0085] Using a coating apparatus having the configuration shown in Figure 1, the slurry was dispersed onto coated particles having a film-like coating liquid attached to their surfaces, and the coating liquid attached to the surfaces of each coated particle was dried to obtain a dry gel powder in which the surfaces of each coated particle were covered with a precursor of the coating material.

[0086] Specifically, the pressure of the air (compressed air) sent from the compressor 31 was set to 0.5 MPa, and the air flowing through the dispersion gas passage 32 at a flow rate of 320 L / min was heated to 200°C by the dispersion gas heater 33, and the air was supplied from the dispersion gas passage 32 to the dispersion section 11 (collision type high-speed airflow dispersion unit). Meanwhile, the slurry was introduced from the slurry passage 17 to the dispersion section 11 at a rate of 8 g / min, and the slurry was dispersed on the coated particles having the coating liquid attached to their surfaces in a film shape. Then, the coated particles having the coating liquid attached to their surfaces in a film shape were flowed into the drying container 41 of the drying section 13, and the coating liquid attached to the surface of each coated particle was dried in the drying container 41, thereby obtaining a dry gel powder in which the surface of each coated particle was covered with a precursor of the coating material.

[0087] Thereafter, the dry gel powder was collected in the collection section 14, and the dry gel powder collected in the collection section 14 was baked at a predetermined temperature to obtain a positive electrode active material powder in which the coated particles, that is, lithium cobalt oxide, were coated with a thin film of lithium niobate.

[0088] In Example 1, the ratio of the weight of the air flowing into the dispersion section 11 to the weight of the particles to be coated flowing into the dispersion section 11 (hereinafter simply referred to as the "mixing ratio") was 80, the ratio of the heat quantity of the air flowing into the dispersion section 11 per unit time to the heat quantity required to evaporate the solvent from the coating liquid flowing into the dispersion section 11 per unit time (hereinafter simply referred to as the "heat quantity ratio") was 6, and the solid-liquid ratio of the slurry was 2:1. In Example 1, there was no adhesion of powder to the inner surface of the drying vessel 41 or generation of agglomerated particles, and no re-aggregation of the particles to be coated that had been dispersed was observed.

[0089] <Example 2> 50 g of the coating solution was placed in a 300 ml container, and while stirring using a magnetic stirrer, 100 g of lithium cobalt oxide (LiCoO2) with an average particle size of 5 μm was added as particles to be coated (positive electrode active material), and the mixture was stirred for several minutes to obtain a slurry.

[0090] Using a coating apparatus having the configuration shown in Figure 1, the slurry was dispersed onto coated particles having a film-like coating liquid attached to their surfaces, and the coating liquid attached to the surfaces of each coated particle was dried to obtain a dry gel powder in which the surfaces of each coated particle were covered with a precursor of the coating material.

[0091] Specifically, the pressure of the air (compressed air) sent from the compressor 31 was set to 0.3 MPa, and the air flowing through the dispersion gas passage 32 at a flow rate of 250 L / min was heated to 200°C by the dispersion gas heater 33, and the air was supplied from the dispersion gas passage 32 to the dispersion section 11 (collision type high-speed airflow dispersion unit). Meanwhile, the slurry was introduced from the slurry passage 17 to the dispersion section 11 at a rate of 8 g / min, and the slurry was dispersed on the coated particles having the coating liquid attached to their surfaces in a film-like form. Then, the coated particles having the coating liquid attached to their surfaces in a film-like form were flowed into the drying container 41 of the drying section 13, and the coating liquid attached to the surface of each coated particle was dried in the drying container 41, thereby obtaining a dry gel powder in which the surface of each coated particle was covered with a precursor of the coating material.

[0092] Thereafter, the dry gel powder was collected in the collection section 14, and the dry gel powder collected in the collection section 14 was baked at a predetermined temperature to obtain a positive electrode active material powder in which the coated particles, that is, lithium cobalt oxide, were coated with a thin film of lithium niobate.

[0093] In Example 2, the mixture ratio was 32, the heat ratio was 2.5, and the solid-liquid ratio of the slurry was 2: 1. In Example 2 as well, there was no adhesion of powder to the inner surface of the drying vessel 41, no generation of agglomerated particles, and no re-agglomeration of the coated particles that had been dispersed was observed.

[0094] <Example 3> 2.5 kg of the coating liquid was placed in a 15 L container equipped with an agitator, and while stirring with the agitator, 5 kg of lithium cobalt oxide (LiCoO2) with an average particle size of 5 μm was added as the particles to be coated (positive electrode active material), and the mixture was stirred for several minutes to obtain a slurry.

[0095] Using a coating apparatus having the configuration shown in Figure 2, the slurry was dispersed onto coated particles having a film-like coating liquid attached to their surfaces, and the coating liquid attached to the surfaces of each coated particle was dried to obtain a dry gel powder in which the surfaces of each coated particle were covered with a precursor of the coating material.

[0096] Specifically, the pressure of the air (compressed air) sent from the compressor 31 was set to 0.3 MPa, and the air flowing through the dispersion gas passage 32 at a flow rate of 2000 L / min was heated to 200°C by the dispersion gas heater 33, and the air was supplied from the dispersion gas passage 32 to the dispersion section 111 (Laval type high-speed airflow dispersion unit). Meanwhile, the slurry was introduced from the slurry passage 17 to the dispersion section 111 at a speed of 240 g / min, and the slurry was dispersed on the coated particles having the coating liquid attached to the surface in a film form. Then, the coated particles having the coating liquid attached to the surface in a film form were flowed into the drying container 41 of the drying section 13, and the coating liquid attached to the surface of each coated particle was dried in the drying container 41, thereby obtaining a dry gel powder in which the surface of each coated particle was covered with a precursor of the coating material. Thereafter, the dry gel powder was collected in the collection section 14, and the dry gel powder collected in the collection section 14 was baked at a predetermined temperature to obtain a positive electrode active material powder in which the coated particles, that is, lithium cobalt oxide, were coated with a thin film of lithium niobate.

[0097] In Example 3, the mixture ratio was 15, the heat ratio was 1.3, and the solid-liquid ratio of the slurry was 2: 1. In Example 3, there was no adhesion of powder to the inner surface of the drying vessel 41, no generation of agglomerated particles, and no re-agglomeration of the coated particles that had been dispersed was observed.

[0098] <Comparative Example> 2.3 kg of the coating liquid was placed in a 15 L container equipped with an agitator, and while stirring with the agitator, 5 kg of lithium cobalt oxide (LiCoO2) with an average particle size of 5 μm was added as the particles to be coated (positive electrode active material), and the mixture was stirred for several minutes to obtain a slurry.

[0099] Using a coating apparatus having the configuration shown in Figure 2, the slurry was dispersed onto coated particles having a film-like coating liquid attached to their surfaces, and the coating liquid attached to the surfaces of each coated particle was dried to obtain a dry gel powder in which the surfaces of each coated particle were covered with a precursor of the coating material.

[0100] Specifically, the pressure of the air (compressed air) sent from the compressor 31 was set to 0.2 MPa, and the air flowing through the dispersion gas passage 32 at a flow rate of 1500 L / min was heated to 150°C by the dispersion gas heater 33, and the air was supplied from the dispersion gas passage 32 to the dispersion section 111 (Laval type high-speed airflow dispersion unit). Meanwhile, the slurry was introduced from the slurry passage 17 to the dispersion section 111 at a speed of 240 g / min, and the slurry was dispersed on the coated particles having the coating liquid attached to the surface in a film form. Then, the coated particles having the coating liquid attached to the surface in a film form were flowed into the drying container 41 of the drying section 13, and the coating liquid attached to the surface of each coated particle was dried in the drying container 41, thereby obtaining a dry gel powder in which the surface of each coated particle was covered with a precursor of the coating material. Thereafter, the dry gel powder was collected in the collection section 14, and the dry gel powder collected in the collection section 14 was baked at a predetermined temperature to obtain a positive electrode active material powder in which the coated particles, that is, lithium cobalt oxide, were coated with a thin film of lithium niobate.

[0101] In the comparative example, the mixture ratio was 15, the heat ratio was 0.8, and the solid-liquid ratio of the slurry was 2: 1. In the comparative example, adhesion of powder to the inner surface of the drying vessel 41 and generation of agglomerated particles occurred, and re-agglomeration of the coated particles that had been dispersed was observed.

[0102] <Summary> The contents (numerical values, etc.) of Examples 1 to 3 and Comparative Examples are summarized in Table 1.

[0103] [Table 1]

[0104] By comparing Examples 1 to 3 with the Comparative Example, it can be seen that when the heat ratio is less than 1, i.e., when the heat amount of the air flowing into the dispersion section 11 per unit time is less than the heat amount required to evaporate the solvent from the coating liquid flowing into the dispersion section 11 per unit time, the powder adheres to the inner surface of the drying container 41, agglomerated particles are generated, and re-agglomeration of the coated particles that were once dispersed occurs, resulting in low dispersibility of the dry gel powder. [Explanation of symbols]

[0105] 1,101: Coating equipment 11,111:Dispersion section 13:Drying section 17: Slurry channel (mixture channel) 21,121:Distribution path 31: Compressor (dispersion gas source) 32: Dispersion gas flow path 33: Distributed gas heater (distributed gas heating source) 41: Drying container (drying path) 45: Drying gas flow path 61: Control unit

Claims

1. a mixture flow path through which a mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent flows; a dispersion gas source for delivering a dispersion gas; a dispersion gas flow path through which the dispersion gas delivered from the dispersion gas source flows; a dispersion gas heating source for heating the dispersion gas flowing through the dispersion gas flow passage; a dispersion section having a dispersion path to which the mixture flow path and the dispersion gas flow path are connected, the mixture flows from the mixture flow path into the dispersion path, the dispersion gas heated by the dispersion gas heating source flows from the dispersion gas flow path into the dispersion path, and the mixture is dispersed by an air flow of the dispersion gas onto the coated particles to which the coating liquid is attached in the form of a film; A control unit, The control unit controls the dispersion gas source so that a ratio of a weight of the dispersion gas flowing into the dispersion path to a weight of the particles to be coated flowing into the dispersion path is 3 or more.

2. 2. The coating apparatus according to claim 1, wherein the control unit controls at least one of the dispersion gas source and the dispersion gas heating source so that the temperature of the dispersion gas flowing into the dispersion path is equal to or higher than a boiling point of the solvent.

3. 3. The coating apparatus of claim 2, wherein the control unit controls at least one of the dispersion gas source and the dispersion gas heating source so that the heat quantity of the dispersion gas flowing into the dispersion path per unit time is equal to or greater than the heat quantity required to evaporate the solvent from the mixed material flowing into the dispersion path per unit time.

4. a mixture flow path through which a mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent flows; a dispersion gas source for delivering a dispersion gas; a dispersion gas flow path through which the dispersion gas delivered from the dispersion gas source flows; a dispersion gas heating source for heating the dispersion gas flowing through the dispersion gas flow passage; a dispersion section having a dispersion path to which the mixture flow path and the dispersion gas flow path are connected, the mixture flows from the mixture flow path into the dispersion path, the dispersion gas heated by the dispersion gas heating source flows from the dispersion gas flow path into the dispersion path, and the mixture is dispersed by an air flow of the dispersion gas onto the coated particles to which the coating liquid is attached in the form of a film; A control unit, The control unit controls at least one of the dispersion gas source and the dispersion gas heating source so that the heat quantity of the dispersion gas flowing into the dispersion path per unit time is equal to or greater than the heat quantity required to evaporate the solvent from the mixed material flowing into the dispersion path per unit time.

5. 5. The coating apparatus according to claim 1, wherein the control unit controls the dispersion gas source so that the pressure of the dispersion gas delivered by the dispersion gas source is 0.15 MPa or more.

6. 5. The coating apparatus according to claim 1, wherein the mixture is adjusted to have a solid-liquid ratio of 2:0.5-3.

7. 5. The coating apparatus according to claim 1, wherein the particles to be coated have an average particle size in the range of 100 nm to 50 μm.

8. a dry gas flow path through which a dry gas flows; 5. The coating device according to claim 1, further comprising: a drying section having a drying path to which the dry gas flow path is connected, and drying the coating liquid adhered to the particles to be coated flowing from the dispersion path into the drying path by the dry gas flow path from the dry gas flow path.

9. The coating apparatus of claim 8 , further comprising a drying gas heating source for heating the drying gas flowing through the drying gas passage.

10. A mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent is flowed from the mixture flow path into the dispersion path, A dispersion gas is delivered from a dispersion gas source to a dispersion gas flow path connected to the dispersion path; The dispersion gas flowing through the dispersion gas flow passage is heated by a dispersion gas heating source; The mixture is dispersed onto the coated particles to which the coating liquid is attached in the form of a film by an air flow of the dispersion gas flowing from the dispersion gas flow path into the dispersion path, A coating method, comprising: setting a ratio of a weight of the dispersion gas flowing into the dispersion passage to a weight of the particles to be coated flowing into the dispersion passage to 3 or more.

11. The coating method according to claim 10, wherein the temperature of the dispersion gas flowing into the dispersion passage is set to a boiling point of the solvent or higher.

12. 12. The coating method according to claim 11, wherein the heat quantity of the dispersion gas flowing into the dispersion path per unit time is equal to or greater than the heat quantity required to evaporate the solvent from the mixture flowing into the dispersion path per unit time.

13. A mixture of particles to be coated and a coating liquid in which a coating material is dissolved in a solvent is flowed from the mixture flow path into the dispersion path, A dispersion gas is delivered from a dispersion gas source to a dispersion gas flow path connected to the dispersion path; The dispersion gas flowing through the dispersion gas flow passage is heated by a dispersion gas heating source; The mixture is dispersed onto the coated particles to which the coating liquid is attached in the form of a film by an air flow of the dispersion gas flowing from the dispersion gas flow path into the dispersion path, A coating method, comprising making the heat quantity of the dispersion gas flowing into the dispersion path per unit time equal to or greater than the heat quantity required to evaporate the solvent from the mixture flowing into the dispersion path per unit time.

14. The coating method according to any one of claims 10 to 13, wherein the pressure of the dispersion gas delivered by the dispersion gas source is 0.15 MPa or more.

15. The coating method according to any one of claims 10 to 13, wherein the mixture is adjusted to have a solid-liquid ratio of 2:0.5 to 2:

3.

16. The coating method according to any one of claims 10 to 13, wherein the particles to be coated have an average particle size in the range of 100 nm to 50 µm.

17. The coating method according to any one of claims 10 to 13, wherein the coating liquid adhered to the particles to be coated in the form of a film is dried.

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