JPH08294621A - High efficiency coating method - Google Patents

Abstract

PURPOSE: To conduct coating, agitation, and drying with a powder agitation tank kept at reduced pressure in a method in which powder is immersed in a coating resin solution in the agitation tank to be coated or is spray coated with the resin solution. CONSTITUTION: A method enables high efficiency spray coating and liquid immersion coating to obtain high quality products and materializes the following remarkable effects: In spray method, since liquid droplets are small in size and distributed uniformly, the coated surface of particles is smooth and the coating film is uniform so that stable properties such as electrification properties and electric properties are obtained. In liquid immersion method, a smooth, uniform coating film is obtained in a short time to obtain stable quality properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating the surface of powder particles with a resin with high efficiency.

[0002]

2. Description of the Related Art A granulating apparatus has been widely introduced since 1970, mainly in the pharmaceutical and food industries, because it can perform small-quantity multi-product production, mixing, granulation, and drying processes in the same container. In addition, the social environment required for granulated products is such that, for small-quantity, high-mix production, granulated products of particle size, density, shape, etc. can be obtained arbitrarily, and mixing, granulation, coating, and drying can be performed by a single facility. Therefore, there has been a demand for a multifunctional FA automated unmanned system capable of arbitrarily obtaining the above-described quality and a combined operation capable of selecting any process. In response to these demands, each device manufacturer has been developing and commercializing a composite granulating device since about 1980, and a device for treating each granulation method of fluidized bed, stirring, and rolling in the same container has been put into practical use. Was done.

This composite type granulation method is often a combination of granulation methods of fluidized bed granulation, stirring granulation and rolling granulation. For example, the combination is shown in Table 1 below. Shown.

[Table 1] Composite granulation combines or fuses the functions of stirring granulation, tumbling granulation and fluidized bed granulation in the same container,
The ability to freely produce quality such as density and particle size, mixing,
It has the function of unit operation such as granulation, drying, coating, etc., and it can be operated arbitrarily according to the application.

Next, specific examples of various composite granulating apparatuses include the following apparatuses. First, as the stirred fluidized bed type, there are "Super Fine Matrix SMA type" manufactured by Nara Machinery Co., Ltd. and "Multiflex Granulator MP type" manufactured by Paulex. As the rolling fluidized bed type, "Spiracoater SP type" manufactured by Okada Seiko Co., Ltd. may be mentioned. The stirring rolling fluidized bed type includes “Spiral Flow SFC type” manufactured by Freund Sangyo Co., Ltd. and “New Marmerizer NQ type” manufactured by Fuji Paudal. Most of the fluidized bed apparatus is a batch type (batch processing type),
Spray granulation (coating) is performed from the top or side of the fluid plate or stirring blade with a spray gun (spray nozzle). The processed product after the spray granulation process is discharged to the outside from the product discharge port via the discharge valve on the lower side surface. The following proposals have been made for these devices and systems.

As a proposal of the representative example, Japanese Patent Publication No. 2-5
No. 6935, Japanese Examined Patent Publication 3-1063, Japanese Examined Examination 3-420
No. 28, Japanese Examined Patent Publication No. 3-42029, Japanese Examined Japanese Patent Publication No. 3-1354
No. 30, JP-B-5-4128, JP-B-5-49901
No. 5, Japanese Patent Publication 5-11508, Japanese Patent Publication No. 5-192555
And Japanese Patent Publication No. 6-186. These publications do not control atomization droplet diameter, unlike the present invention, so that many split recoil droplets are generated when powder particles collide. Are generated, and these droplets adhere to the inner wall surface of the apparatus, the rotating blades, or other powder particles, and a lot of aggregates are generated.
At the same time, the split recoil liquid droplets are much smaller than the spray liquid droplets, so that some of them solidify instantly, and the solidified coating material is dried and solidified (coat dust) in the powder surface. Adheres to and deteriorates the coat quality.

On the other hand, a dipping method for forming a smooth film on the surface of the substance to be coated has also been introduced. This method is a method of immersing a tablet pill in a coating solution in the field of pharmaceuticals and the like, and pulling it up and drying it, but it was not suitable for coating powder particles having a small particle size. In the case of a powder having a small particle diameter, the particles adhere to each other and agglomerate in the drying step after the immersion to finally become a nodule state, which is difficult in the field where the form of primary particles is required. Further, in a solvent having a solvent boiling point of 100 ° C. or higher in the coating liquid, the temperature in each of the above-mentioned granulating apparatuses is often lower than the boiling point, so that a defective product may be produced. In particular, in a mixing granulation method in which drying is performed by heating with a jacket, a mixer, or the like, the tendency is remarkable, and the particles after coating tend to form block-like lumps. In addition, the residual solvent gas is likely to fill the inside of the device, which poses a problem in terms of environment and safety. On the other hand, each of the granulation methods introduced above is batch processing (batch method), and at the same time, the spraying method and the dipping method have long processing time per batch and poor productivity. Therefore, in order to improve the productivity, it is necessary to install the same model or a large-scale device in parallel to improve the productivity, which leads to an increase in product cost.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional coating method and to coat powder particles with high efficiency, and to provide a high-quality coated product easily. It is to provide a coating method using the obtained granulating apparatus.

[0008]

According to the present invention, firstly, in a coating method in which a powder or granular material to be coated is coated while being immersed in a coating resin solution in a powder or granular material stirring tank, Provided is a high-efficiency coating method characterized in that coating, stirring, and drying are performed in a granular stirring layer under reduced pressure. That is, in this coating method, the substance to be coated (powder or granules) is charged into the powder / granule stirring / granulating device of the coating apparatus, and then the coating resin solution is charged until the substance to be coated is completely immersed. In this state, the stirring layer is closed and the stirring blade and the crushing blade are rotated for 2 to 5 minutes to immerse all the powder and granules. Then, in that state, the internal pressure in the stirring layer is set to 500 mmHg.
Reduce the pressure to the following and coat, stir, and dry. When the water content in the layer becomes 20% or less, the number of rotations of the stirring blade and the crushing blade is increased to obtain a coating powder or granule.

Further, according to the present invention, secondly, in the coating method in which the powdery or granular material to be coated is spray-coated in a state in which the powdery or granular material is kept in a tumbling flow state in the powdery or granular stirring tank, the powdery or granular material is provided. Coat / stir in a reduced pressure inside the stirring layer
A high efficiency coating method characterized by performing drying is provided. That is, this coating method is a coating method in which the granular material is tumbled and fluidized in a granular material agitation granulating device, and the coating resin solution is sprayed onto the granular material in that state, with the agitation granulation at that time. The method is characterized in that the internal pressure of the apparatus is in a reduced pressure state.

According to the present invention, thirdly, in the coating method described in the first or second aspect, the powdery or granular material stirring tank comprises a stirring blade for stirring and a solution for crushing. It is equipped with a crushing blade and has a jacket that can be cooled and heated, and during coating, stirring and drying, the jacket heating temperature is equal to or higher than the boiling point of the solvent in the coating resin solution. A high-efficiency coating method is provided. Fourthly, in the coating method described in the above-mentioned third, the rotation of the stirring blade and the crushing blade provided in the powdery particle stirring tank, when coating, stirring and drying A high-efficiency coating method is provided, which is performed at a rotation speed of 1/2 or less of the rotation speed and is coated in a ratio of rotation of a stirring blade to rotation of a crushing blade of 1: 2 to 1: 4. Ru That is, the third coating method is a powder / granule stirring / granulating apparatus having a stirring blade and a crushing blade for stirring the powder / granular material, and the temperature inside the jacket that allows cooling / heating is the boiling point of the solvent in the coating resin solution. The method is characterized by coating, stirring, and drying at a heating temperature equal to or higher than the temperature, and the fourth coating method is a stirring blade and a crushing blade installed in the powder / granule stirring layer. The method is characterized in that the number of rotations is within the range of 1: 2 to 1: 4, and that the number of rotations during drying is twice or more that during coating and stirring.

Further, according to the present invention, in the coating method described in the second aspect, the spray coating has a spray droplet diameter that is ⅕ or less of the particle diameter of the powder or granular material, and has an average particle diameter of 2 to 2. Provided is a highly efficient coating method, characterized in that it is carried out with a spray droplet of 15 μm, and sixthly,
In the coating method described in the above fifth, the spray droplet diameter is a value measured by a laser type particle size distribution measuring device and is a ratio (90%) of a 10% value and a 90% value of a cumulative volume value.
% Value / 10% value) is less than or equal to 5.00, and seventhly, in the coating method described in the above-mentioned first, the inside of the granular material stirring layer is A high-efficiency coating method is provided, which is characterized by being under a reduced pressure atmosphere having an internal pressure of 500 mmHg or less.

[0012]

In the present invention, as the coating device, for example, a stirring and mixing granulating device as shown in FIG. 1 is used. FIG.
In the above, 1 is a granule agitation granulator, 2 is a granule crushing blade, 3 is a granule agitator blade, 4 is a spray nozzle, 5 is a cooling / heating jacket, 6 is a bag filter, and 7 is for decompression. A vacuum pump, 8 is a coating resin solution supply pump, 9 is a solvent trap device, 10 is a solvent recovery device, and 11 is a recovered solvent. In the granulating step (coating / stirring / drying), the powder / granular material stirring / granulating device 1 is supplied with the powder / granular material stirring blade 3 and the powder / granular material crushing blade 2 are simultaneously rotated to Form a rolling fluidized bed of granules.

Liquid immersion granulation method, which is the first coating method of the present invention (schematically displayed on the right half side of FIG. 1)
Is charged until the powder / particle crushing blade 2 is hidden, and then the coating resin solution 12 is charged until the powder / particle 13 is completely immersed. Then, in this state, the powder / granule stirring / granulating device 1 is closed, and the powder / granular material stirring blade 3 and the powder / granular material are provided for 2 to 5 minutes so that the resin in the coating resin solution adheres to the surfaces of all the particles of the granular material. The crushing blades 2 are rotated simultaneously. afterwards,
Coating, stirring, and drying are performed while depressurizing the inside of the powder-granulate agitation granulator with a vacuum pump 7 for depressurization so that the internal pressure of the layer becomes 500 mmHg or less.

On the other hand, in the spray method (schematically displayed on the left half side of FIG. 1) which is the second coating method of the present invention, the granular material stirring blade 3 and the granular material crushing blade 2 are rotated. Then, the granular material is brought into a rolling fluid state in the apparatus. The coating liquid is supplied to the powder or granular material in that state by the coating resin solution supply pump 8, and the coating resin solution atomized into fine particles is sprayed through the spray nozzle 4. The pressure in the apparatus at that time is the same as in the liquid immersion granulation method, and coating, stirring, and drying are performed.

The exhaust solvent generated during coating, stirring and drying in the reduced pressure atmosphere of the present invention is recovered by the solvent trap device 9, and only hot air gas is exhausted from the exhaust pipe. The coated granular material of the present invention is controlled by a measuring device (moisture meter or solvent gas concentration meter) installed in the granular material agitation granulator, and the water content in the layer is 20%.
When it becomes the following, it is collected and supplied to the next process.

The coating method of the present invention may be either a method of spraying the coating liquid or a method of immersing the powder particles in the coating liquid. In both the spraying method and the dipping method, jacket heating is performed during coating and drying. The heating temperature at that time is set to a temperature higher than the boiling point of the solvent in the coating resin solution. Since this temperature lowers the boiling point of the solvent in the depressurized state in the apparatus, the jacket temperature is set while confirming the depressurized state. Further, the pressure in the apparatus of the present invention is reduced to 500 mmHg or less, and coating /
Drying is performed, but the reduced pressure is weak (500 mmHg to 760
mmHg) and the drying time during the drying operation becomes long, and agglomerated particles frequently occur, resulting in a significant decrease in production efficiency.

Next, each coating method in the present invention will be described. The method of spraying is such that the diameter of the coated droplets to be sprayed is 2 to 15 μm in average particle diameter, and the ratio of the 10% value and the 90% value (90% value / 10% value) of the cumulative volume value is 5.
It is controlled to be 00 or less and spray coating is performed. The spray droplet diameter is preferably 3 to 10 μm. Spray droplet size is 15
If it exceeds μm, coated particles (small particle size particles)
Since the dried film formed on the surface is formed as large irregularities, it becomes a non-uniform coat film. In addition, since the inside of the film is difficult to dry at the protruding part (even if the surface of the film is dried, the inside remains in an undried state), contact with other coating substances (small-sized powder particles after coating) At the time of collision and at the time of collision, they become aggregates. Also, if the droplet diameter is large, the desired coating film thickness cannot be obtained, and when the droplet collides with the particles to be coated, the droplets break up and become fine split recoil droplets, which adhere to the inner wall of the device. Or it is instantly dried and solidified and discharged to the outside of the layer, which causes a decrease in yield. On the other hand, when the diameter of the sprayed droplets is less than 2 μm, the solvent component contained in the sprayed droplets instantly evaporates (due to an increase in dry concentration), and it becomes impossible to form a film. For this reason, the resin component in the coating liquid may become dry solid particles, which may be deposited as scattered matter or resin debris on the inner wall of the apparatus, or fly to the exhaust side to reduce the yield.

In the coating by the spray method of the present invention, since the atomized droplet size is made fine and the coating atmosphere (environment) is in a reduced pressure state, a uniform film can be obtained regardless of whether the coating liquid solvent is a solvent system, an aqueous system or a high solid solution. It can be formed. In particular, in the case of an aqueous system, the boiling point of water is higher than that of a solvent system, so that a film can be formed more effectively (efficiently). In the coating by the spray method of the present invention, the sprayed droplets have a ratio of the 10% value and the 90% value of the cumulative volume value (90% value / 10% value).
However, droplets having a particle size distribution of 5.00 or less are sprayed and coated. However, when the ratio is 5.00 or more, the film thickness and the film uniformity coated with the small particle size droplets and the film thickness and the uniformity coated with the large particle size side droplets in the liquid droplet distribution. to differ greatly. Therefore, the quality variation in the same processed product becomes large, and the desired quality characteristics may not be obtained depending on the sampling.

In the spray coating method of the present invention, spraying is carried out under the above-mentioned spraying method and conditions, but the coating is carried out in the solvent boiling temperature range in the sprayed droplets in the coating apparatus. If the droplets are coated in the solvent boiling temperature range, they will collide with the surface of the powder particles immediately after spraying.
A film is formed, and at that moment, the solvent in the droplets is evaporated and the film is solidified. However, if the temperature environment in the coating apparatus is lower than the boiling temperature range of the solvent in the droplets, the inside of the film tends to exist in a state where it does not solidify even after being formed into a film after coating.
In that case, when the particles contact or collide with other particles, and further contact or collide with the inner wall surface, adhesion, aggregation, sticking, etc. occur.

On the other hand, in the case of the method of immersing the powder or granular material to be coated in the coating resin particles, in the apparatus in which the powder or granular material to be coated is charged with the coating resin solution so that the coating thickness after drying becomes the target thickness. Put in. And
Stir and mix until all the coated particles are soaked. It is sufficient that the stirring and mixing time is 2 to 5 minutes. The agitation and mixing granulation layer of the present invention has a jacket between the inner wall and the outer wall through which cold / hot water can flow, and the inside of the jacket is heated during coating / drying. The jacket heating method and conditions at that time may be substantially the same as the spray method, and the apparatus internal pressure may be the same. However, it is necessary to change [rotation speed of stirring blade and crushing blade during coating] and [rotation speed of stirring blade and crushing blade during drying]. The rotation speeds of the stirring blade and the crushing blade during coating are [200 to 60], respectively.
0 rpm, 700 to 2000 rpm], and the drying is performed at a rotation speed of [1.5 to 3 times] each blade rotation speed during coating. If the number of rotations of the blade during coating is lower than the number of rotations described above, the uniform mixing and stirring action does not work, and it becomes difficult to coat the entire agitated powder or granular material. On the contrary, if the blade rotation speed is high, the stirring and mixing action does not occur, but the coating resin solution jumps up, and the resin adhesion efficiency decreases (during coating).
The coated resin may peel off or the powder particles themselves may be broken (crushed). (When dry)

The coating method of the present invention is a high-efficiency coating method that solves the above-mentioned problems by forming a more uniform film by either a spraying method or a liquid immersion method.

[0022]

EXAMPLES Next, the present invention will be described in more detail by way of examples. The fixed conditions common to each example are as follows. Coating liquid used: 10% water-soluble resin solution (PVA-20
5: Kuraray Co., Ltd.) 20% resin solution (solvent: toluene) Powder particles used: Ferrite carrier having an average particle diameter of 30 to 100 μm Each carrier is adjusted to a target particle size by sieving Treatment amount: 2 kg / batch Others: Liquid The droplet size is determined by measuring with a laser type particle size distribution analyzer (LDSA-2300A). In addition, the calculation method was calculated by the formula of [Rosin-Rammler distribution function], and the SMD (body area diameter) value was used as the droplet average particle diameter. For the volume particle size ratio [D90 / D10], the volume cumulative value obtained by the above calculation method is calculated, and the D90 / D10
Was calculated. For the boiling point of the solvent, the temperature at which each solvent bumps at the time of depressurization was measured, and the temperature at that time was taken as the solvent boiling point, and the jacket heating temperature was set.

Examples 1 to 8 Ferrite carriers were coated with a coating solution under the conditions shown in Table 2 to obtain PVA-coated carriers.

[0024]

[Table 2]

Comparative Example 1 A PVA-coated carrier was obtained under the same conditions as in Example 1, except that the pressure inside the apparatus of Example 1 was changed from [500 mmHg] to [normal pressure (760 mmHg)].

Comparative Example 2 A PVA-coated carrier was obtained under the same conditions as in Example 2, except that the [agitating blade rotation speed] and the [crushing blade rotation speed] of Example 2 were set lower than the proper rotation speed.

Comparative Example 3 A PVA-coated carrier was obtained under the same conditions as in Example 5, except that the [jacket heating temperature] in Example 5 was set lower than the solvent boiling point temperature.

COMPARATIVE EXAMPLE 4 PVA-coated carrier under the same conditions as in Example 6 except that the setting of [rotation speed of stirring blade] and [rotation speed of crushing blade] in Example 6 were set higher than the appropriate speed. Got

Comparative Example 5 A PVA-coated carrier was prepared under the same conditions as in Example 1 except that the pressure inside the apparatus of Example 1 was changed to weak decompression [700 mmHg] and the [jacket heating temperature] was set lower than the solvent boiling point. Obtained.

Comparative Example 6 [Internal pressure] of Example 3 was changed to [normal pressure (760 mmH
g)] was used, and a PVA-coated carrier was obtained under the same conditions as in Example 3.

Comparative Example 7 A PVA-coated carrier was obtained under the same conditions as in Example 4, except that the [spray droplet size] and [volume particle size ratio] of Example 4 were increased.

Comparative Example 8 A PVA-coated carrier was obtained under the same conditions as in Example 4, except that the [agitating blade rotation speed] and the [crushing blade rotation speed] of Example 4 were set higher than the appropriate rotation speed.

Comparative Example 9 A PVA-coated carrier was obtained under the same conditions as in Example 3, except that the [agitating blade rotation speed] and the [crushing blade rotation speed] of Example 3 were set lower than the proper rotation speed.

Comparative Example 10 A PVA-coated carrier was obtained under the same conditions as in Example 7, except that the [sprayed droplet size] of Example 7 was made finer than the proper droplet size.

Comparative Example 11 [Internal pressure] of Example 8 was weakly reduced [700 mmHg].
And the [jacket heating temperature] was set lower than the solvent boiling point to obtain a PVA-coated carrier under the same conditions as in Example 8.

The conditions adopted in the above Comparative Examples 1 to 11 are summarized in Table 3.

[0037]

[Table 3]

Quality evaluation was performed on the PVA-coated carrier thus obtained. The results are shown in Table 4. In addition,
The evaluation method etc. were as follows. 1. The spraying method and the liquid immersion method differ in the set resin solid content, and therefore the coating and drying times are different. 2. The degree of adhesion to the inner wall surface of the apparatus was visually evaluated and ranked into 5 levels. The best one is [◎], and the worst one is [x]. 3. Regarding the degree of cohesion, the total amount of the powder particles before coating coating and the resin solid content when the coating liquid after spraying and liquid immersion was dried was taken as the total amount, and the weight ratio of the weight remaining above the standard mesh was 5 It was divided into ranks and represented by ⊚ to × like the degree of adhesion. 4. The "fine product generation rate" represents a weight ratio obtained by sieving the powder particles after coating with a standard mesh and dividing the passed amount by the total weight after coating. 5. [Coating resin residue generation rate] was observed by observing the particle surface after coating with an electron microscope photograph, and the degree was divided into 5 levels, and those with almost no residue were rated as [◎], and the rank was classified as the inner wall adhesion evaluation. The same method was used. 6. In [Coat film thickness variation], the minimum film thickness and the maximum film thickness were measured, and the rank was classified into 5 stages according to the difference. The evaluation rank was the same as the other five-level evaluation methods. 7. [Surface property] was evaluated as the surface condition at the time of evaluating the degree of coating resin residue generation, and the one having little unevenness was marked with [A]. 8. [Yield] is the ratio (wt%) of the recovered weight after coating to the total input amount. However, the agglomerated powder particles were excluded from the output after coating (because agglomerated products cannot be used as products). 9. The [charging characteristics / electrical characteristics] are classified into five levels by the degree of deviation from the reference value (target value), and those with less deviation are indicated by [⊚], and evaluated according to the degree of deviation. 10. [Comprehensive evaluation] includes product productivity, quality, etc.
The overall superiority was marked with [◎] and stratified into 5 stages.

[0039]

[Table 4]

[0040]

According to the coating method of the present invention, the powder to be coated is coated in a state where the powder or granular material is immersed in the coating resin solution in the powder or granular material stirring tank, or the powder or granular material to be coated is stirred. In a coating method in which spray coating is carried out in a state of being kept in a tumbling flow state in a tank, coating / stirring /
Since the configuration is such that drying is performed, the following remarkable effects can be achieved, and highly efficient spray coating and liquid immersion coating are possible, and a high-quality product can be obtained. (A) In the spray method, since the droplet diameter is small and has a uniform distribution, the surface state of the particles after coating is smooth and a uniform coating film is obtained. Therefore, each quality characteristic value (charging characteristic, electric characteristic, etc.) becomes stable. (B) In the liquid immersion method, a coat film having a smooth particle surface can be formed in a short time and a uniform coat film can be obtained. Therefore, the quality characteristic values are stable as in the spray method. (C) Since the amount of deposits on the inner wall of the coating device is reduced, maintenance is facilitated. (D) Since the aggregation of particles during coating and drying is reduced, quality characteristic values are stable and the yield is improved. In addition, productivity improvement and cost reduction can be achieved. (E) Since coating is performed under a reduced pressure inside the apparatus, even a solvent with a high boiling point such as water that is difficult to dry can be coated and dried in a short time, improving productivity.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a stirring and mixing granulation apparatus used in the present invention, in which the right half side of the powder / granular stirring layer is in the state at the time of liquid immersion granulation, and the left half side is spray granulation. The state at the time of the grain method,
Each is shown schematically.

[Explanation of symbols]

 1 Powder / Granule Stirring Layer 2 Powder / Granule Crushing Blade 3 Powder / Granule Stirring Blade 4 Spray Nozzle 5 Cooling / Heating Jacket 6 Bag Filter 7 Vacuum Pump for Decompression 8 Coating Resin Solution Supply Pump 9 Solvent Trap Device 10 Solvent Recovery Pipe 11 Recovery solvent 12 Coating resin solution 13 Powder and granules 14 Water content detection device

Claims (7)

[Claims] 1. A coating method in which a powder or granular material to be coated is coated while being immersed in a coating resin solution in a powder or granular material stirring tank, wherein the powder or granular material stirring layer is coated, stirred and dried under reduced pressure. A high-efficiency coating method comprising: 2. A coating method in which a powdery or granular material to be coated is spray-coated while being kept in a tumbling flow state in a powdery or granular material stirring tank, wherein the powdery or granular material stirring layer is coated / stirred under reduced pressure.・ A high-efficiency coating method characterized by performing drying. 3. The powder / granule stirring tank comprises a stirring blade for stirring and a crushing blade for crushing and cooling
3. A jacket capable of heating, wherein the jacket heating temperature is equal to or higher than the boiling point of the solvent in the coating resin solution during coating, stirring and drying. High efficiency coating method. 4. The stirring blade and the crushing blade provided in the powder and granular material stirring tank are rotated at a rotational speed of 1/2 or less of the rotational speed at the time of stirring and drying during coating, and the stirring blade is rotated. 4. The high-efficiency coating method according to claim 3, wherein the coating is performed in a ratio of rotation of the crushing blade to 1: 2 to 1: 4. 5. The spray coating has a spray droplet diameter that is ⅕ or less of the particle diameter of the powder or granular material and has an average particle diameter of 2 to 15.
3. Implementation with atomized droplets of μm.
The high-efficiency coating method described. 6. The spray droplet diameter is a value measured by a laser type particle size distribution measuring device, and the ratio of the 10% value and the 90% value of the cumulative volume value (90% value / 10% value) is 5. The high-efficiency coating method according to claim 5, wherein the high-efficiency coating method is 00 or less. 7. An internal pressure of 500 is provided in the powdery particle stirring layer.
The high-efficiency coating method according to claim 1, wherein the high-efficiency coating method is performed under a reduced pressure atmosphere of mmHg or less.