JP2784477B2 - Liquid coating equipment for powder - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an apparatus for coating powder surfaces with a liquid, such as is used for coating constarches with aqueous solutions of vitamins and the like.

(Prior Art) In general, surface modification is often performed, for example, by coating a substance having low adherence for the purpose of improving the handleability of a substance having poor fluidity with fine powder and improving the fluidity thereof. .

Conventionally, for such a surface modification, various devices have been provided which are used to coat a desired liquid on a powder surface.For example, a powder is fluidized by air, and a liquid is supplied from an upper portion. There are known a type in which coating is performed by spraying, and a type in which a liquid is mixed with powder agitated by high-speed rotating blades (super turbo type).

(Problems to be solved by the invention) However, in the above-described liquid coating method,
The powder to be coated is fine powder (for example, <30μ
It is known that in the case of m), there is a disadvantage that the coating cannot be properly performed. This is because, in such fine powder, the powder tends to agglomerate to form secondary particles.For example, even if the powder is floated and fluidized by air, the aggregated secondary particles are present in the powder in the floating state. This is usually due to a significant percentage, which makes it impossible for the primary particles forming the secondary aggregated particles to have a suitable surface coating.

The inventor of the present invention has solved the problems of the conventional apparatus, and has made intensive studies on the development of an apparatus capable of suitably realizing the surface coating of fine powder that easily forms secondary particles by aggregation. It has been reached.

That is, the present invention provides a coating apparatus capable of suitably realizing coating of a powder surface by sufficiently dispersing powder in a state of primary particles in an air stream and mixing a coating liquid in a mist state into the air stream. It is intended to provide.

(Means for Solving the Problems) The liquid coating apparatus for powder according to the present invention which achieves the above object is characterized by a cyclone that slowly drops the powder by using a swirling air flow, and a cyclone of the cyclone. A mixing unit including a powder input device for inputting the powder in a dispersed state from the top, a coating liquid supply device for mixing the coating liquid to be attached to the powder surface into the swirling air flow in a mist state, and the mixing unit. And a coating unit for externally heating or cooling through the cyclone cylinder wall while maintaining the swirling flow of the powder in the cyclone connected to the air conditioner.

As the powder charging device in the above configuration, an airflow type disperser of a type in which high-speed air flow is blown into the narrow passage to disperse the powder while passing the powder into the narrow passage is used. A preferred example is a configuration in which the contained air flow is introduced into the upper part of the cyclone.

As a method of mixing the coating liquid in the mist state into the swirling flow of the cyclone, a method in which the liquid is previously contained in a mist state in a high-speed air stream blown into the air-flow type disperser, or a spray nozzle inside the cyclone A method of spraying can be exemplified.

The coating apparatus according to the present invention is typically used in the pharmaceutical industry and the like to coat a liquid in which a medicinal substance is dissolved in an excipient such as constarch and heat and evaporate the liquid to coat the excipient with the drug. In addition to this, it can be used as a coating device for modifying the surface of a powder requiring complex properties. Further, it can be used in such a manner that a material to be protected and a liquid protective agent (eg, gelatin) are brought into contact with each other and cooled after coating to form a protective film.

According to the present invention, the surface coating of the desired liquid can be appropriately performed on the surface of the primary particles of the fine powder, which easily forms the secondary particles, by employing the above-described configuration.

(Examples) Hereinafter, the present invention will be described based on examples shown in the drawings.

FIG. 1 shows an overall outline of a liquid coating apparatus for powder, and this apparatus of this embodiment is composed of the following three main parts. That is, the first part is a liquid-powder mixing part constituted by using the mixing cyclone 1 as a core, and the second part is a coating part comprising a coating cyclone (tube) 2 for completely coating the liquid on the powder surface. The third part is a collecting part for collecting and collecting the dried powder by the cyclone 3.

The liquid-powder mixing section blows the powder conveying airflow from the blower 12 into the upper part of the mixing cyclone tower 1 from the tangential direction of the outer circumference of the pipe (see FIG. 1 (b)). In addition, a gas flow type dispersing machine 50 shown in FIG. 2 is mounted on the upper part of the mixing cyclone tower 1, and the powder is dispersed by a high-speed air flow containing the coating liquid in a mist state. The dispersed air flow is introduced from the upper part of the mixing cyclone through the introduction cylinder 13.

The air-flow type disperser 50 of this embodiment can be configured by applying, for example, the one described in JP-A-59-213464. An example of the air-flow type disperser 50 will be described in detail with reference to FIG. Then, at the upper end position of the introduction cylinder 13 above the mixing cyclone 1,
The lower body 51 of the disperser 50 is fixed by bolts or the like (not shown). The lower body 51 has a projection 52 in the center of which is formed a vertical cylindrical through hole 53, and the through hole 53 in the projection 52 has the smallest diameter at an intermediate position in the vertical direction. A crack portion is provided, and an upper portion is formed with an upper tapered tubular portion 53a having a tapered shape that opens upward in the upper portion, while a taper shape that opens downward is formed in the lower portion. A lower tapered cylindrical portion 53b is formed.

On the lower body 51, an upper body 54 is fixed by screwing a screw portion 55, and a concave portion 56 provided at the bottom of the upper body 54 is airtightly fitted to the projection 52 of the lower body 51. The space 5 in which the upper opening of the upper tapered cylindrical portion 53a surrounded by the concave portion 56 and the projecting portion 52 faces
8 is formed. The upper body 54
The upper tapered tubular portion 53 of the lower body 51
There is provided a nozzle projection 57 that fits into a and forms a passage as a narrow annular gap with the wall surface of the cylindrical portion 53a.

In the air-flow type disperser 50 having the above configuration, the upper body 54
Is formed with a hopper portion 59 which is gradually opened to a large diameter toward the upper side. In this hopper portion 59, powder is supplied from a powder storage tank 60 by a screw feeder 61 as shown in FIG. It is supplied in a fixed amount. The bottom of the hopper portion 59 of the present example is located at a position close to the concave portion from an intermediate position of the upper tapered tube portion 53a through a powder passage 59a vertically penetrating the nozzle projection 57. It is in open communication with 53a.

On the other hand, compressed air from the compressor 70 is piped into the space 58 through a port 58a as shown in FIG.
It is supplied through 71. In the middle of the pipe 71 from the compressor 70, a liquid sending pipe 82 for sending a liquid from a coating liquid storage tank 80 by a pump 61 is connected so as to merge with each other. It is introduced into the space 58 of the disperser 50 and is ventilated to the mixing cyclone 1 side through the annular narrow passage formed between the through hole 53 of the lower body 51 and the nozzle projection 57 of the upper body 54. It has become so.

In the air-flow type dispersing machine 50 having such a configuration, when the powder is supplied from the screw conveyor 61 to the hopper portion 59 and the air flow containing the coating liquid is passed through the cavity 58 at a high speed, the air flow becomes Nozzle protrusion from void 58 to through hole 53
The powder is sucked and dropped from the opening of the nozzle projection 57 by the ejector effect of the high-speed air flow when passing through the annular narrow passage between the 57 and the mixing cyclone 1 side. As a result, even if the powder is generally a fine powder that easily forms secondary aggregated particles, the proportion of the fine powder dispersed in the state of primary particles is significantly increased. Further, when the air flow containing the coating liquid is jetted from the space 58 to the through hole 53 at a high speed, the coating liquid is in a mist state. The fine powder in the dispersed state, and the high-speed air stream containing the coating liquid in the mist state move into the mixing cyclone 1 as described above, and the powder slowly descends downward while swirling due to the swirling flow of the cyclone. During a predetermined residence time in the cyclone required for the descent, the coating liquid and the powder in the gas are mixed, and the liquid mist adheres to the powder in the state of the primary particles.

The speed of the swirling air flow for swirling the gas and the powder introduced into the mixing cyclone 1 from the upper portion is too high, and the loss is large if the swirling speed is too low. ， Because powder adheres easily,
It is necessary to determine the speed of the swirling flow in consideration of the powder transport force and transport time in the entire system.

Thus, the first liquid-powder mixing unit is configured.

The powder having a predetermined liquid adhered to the surface thereof in the mixed cyclone 1 passes through a duct 14 connected to the bottom of the mixed cyclone 1 and, due to the transport force of the swirling air flow, forms the coating of the second part. It is transported to the upper part of the coating cyclone 2.

The coating cyclone 2 includes an inner pipe 21 and an outer pipe 22, and a low-temperature or high-temperature liquid flows in a space between the inner pipe 21 and the outer pipe 22. Further, as shown in FIG. 1 (b), the duct 14 is connected to the upper part of the tower so as to form a semicircular blow, thereby generating a swirling air flow and required for cooling or drying. A predetermined residence time is obtained.

In this coating cyclone, the powder to which the liquid has adhered moves downward while rolling on the inner pipe wall surface by the swirling air flow, so that the liquid uniformly covers the surface of the powder particles, and further heat is given from the wall, Alternatively, heat is deprived by the wall, and a stable coating film is formed on the particles.

Next, the powder that has reached the lower part of the coating cyclone 2 passes through the duct 24 connected to the bottom and is transported by the above-described swirling air flow to the collection cyclone 3 in the powder recovery part, which is the third part. Transported to the top.

The third part is connected to the upper part of the cyclone 3 so that the duct 24 forms a semicircular blow at the upper part of the cyclone tower as shown in FIG. A collection container 31 is arranged, and an exhaust duct 32 for discharging transport air upward from the upper portion is connected to reach a bag filter 33.

According to the above configuration, the desired liquid can be coated on the surface of the fine powder dispersed in the state of the primary particles while being transported by air.

The present invention is not limited to the above embodiment.

For example, in the above-mentioned embodiment, the surface of the powder that descends while swirling for a predetermined time in the first liquid-powder mixing section and stays in the cyclone should be coated on the surface. Although the liquid is contained in the high-speed air passing through the air flow disperser in a mist state, it is also preferable to use a form in which the liquid is directly sprayed into the mixing cyclone 1.

FIGS. 3 and 4 show an outline of the structure of this type of mixing cyclone. In the example of FIG. 3, the spray nozzle 90 is located at a position slightly lower than the position where the swirling air flow of the tower of the mixing cyclone 1 is blown. Is arranged so that the coating liquid can be sprayed. In this case, the supply path of the high-pressure gas for powder dispersion to be introduced into the gas flow type dispersion device 50 may be partially branched, and the high-pressure gas may be supplied to the liquid supply pipe 91 of the spray nozzle 90.

In the example of FIG. 4, in order to prevent the powder from adhering to the cyclone wall just below the spray nozzle 90 in the example of FIG. 3, a truncated cone 92 is arranged so that the speed of the cyclone swirling air flow can be adjusted. This is shown. By controlling the speed of the swirling air flow (for example, increasing the speed of the swirling speed), it is possible to reduce the tendency of the powder and the like to stay and adhere at a position close to the cyclone wall surface.

In addition to these examples, by blowing high-temperature air or dry air into the first part of the mixed cyclone 1, the powder transport gas can also serve as a drying action. In this case, the second part may be configured as a cooling zone for cooling the high-temperature air.

(Effects of the Invention) According to the present invention, a coating process can be performed by contacting a coating liquid while rotating a fine powder dispersed in a state of primary particles and staying inside a cyclone tower for a predetermined time. In addition, there is an effect that the coating of the surface of the primary particles can be efficiently performed even on the powder which easily forms the secondary aggregated particles.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an example of a schematic configuration of a powder liquid coating apparatus according to the present invention, and FIG. 2 is an enlarged view of the configuration of an air flow type dispersion machine used in FIG. FIGS. 3 and 4 show other examples of the mixed cyclone. 1 mixed cyclone 2 coating cyclone 3 collection cyclone 11 blow duct 12 blower 14 duct 21 inner pipe 22 outer pipe 24 duct 31 recovery Vessel 32 32 Duct 33 Bag filter 50 Air flow disperser 51 Lower body 52 Projection 53 Through hole 53a Upper tapered tube 53b Lower tapered tube 54 ... Upper body, 55 ... Screw part 56 ... Recessed part, 57 ... Nozzle protrusion 58 ... Void, 58a ... Port 59 ... Hopper part

Continuation of the front page (72) Inventor Rikuo Kokubu 3-15-11 Baba, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture (56) References JP-A-61-178058 (JP, A) JP-A-63-4871 (JP, A) JP-A-60-64647 (JP, A) JP-A-50-22037 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B05C 3/00-3/109 A61J 3 / 02

Claims (4)

(57) [Claims] A cyclone for slowly dropping the powder on a swirling air flow, a powder feeding device for feeding the powder in a dispersed state from the top of the cyclone, and a mist state for a coating liquid adhering to the powder surface. A mixing unit comprising a coating liquid supply device to be mixed into the swirling air flow, and externally heating or cooling through the cyclone cylinder wall while maintaining the swirling flow of the powder in the cyclone connected to the mixing unit. A liquid coating apparatus for powder, comprising: a coating section for performing coating. 2. The above-mentioned powder feeding device introduces an air flow containing a dispersed powder in which a high-speed air flow is blown into the narrow passage while the powder is passed through the narrow passage to disperse the powder into the upper part of the cyclone. The liquid coating apparatus for powder according to claim 1, wherein the coating is performed. 3. The liquid coating of powder according to claim 1, wherein the air blown into the powder input device for dispersion of the powder contains the coating liquid in the mist state. apparatus. 4. The powder coating apparatus according to claim 1, wherein the coating liquid is mixed into the swirling air flow by a spray nozzle disposed inside the cyclone.