JPH0461688B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention uses a mechanical method to wrap the surface of powder (hereinafter referred to as mother particle) with fine powder, modifying the surface, and imparting new functionality. The present invention relates to a powder surface modification method and apparatus for the same.

[Conventional technology]

Conventionally, various surface improvement measures have been attempted in order to prevent caking, discoloration, and deterioration of the base particles, or to improve physical and chemical properties such as dispersibility. As one of the methods, a fine powder as a coating material is dissolved in a solvent and mixed with base particles by stirring or spraying, other electrostatic deposition methods, vacuum evaporation methods, etc. are used.

[Problems to be Solved by the Invention] The method of dissolving the fine powder in a solvent and attaching it (wet attachment method) has problems such as requiring time and effort for drying. Furthermore, the electrostatic adhesion method and the vacuum evaporation method require expensive equipment and are limited by the properties of the fine powder to be deposited.
Furthermore, in either method, the fine powder is merely attached to the surface of the base particles and has poor adhesion, so that it may peel off in the next step, resulting in variations in quality.

In view of the above, an object of the present invention is to eliminate the above-mentioned conventional drawbacks and mechanically reliably attach fine powder to base particles.

[Means to solve the problem]

The method of the present invention for achieving the above object includes a stirrer that stirs a base particle and a fine powder to be impregnated and coated on the surface of the base particle to adhere the fine powder to the surface of the base particle; The base particles are made to collide with the collision plate by the pressure air flow, and the fine powder is pressed against the base particles, and the mixture is returned to the stirrer again, and the mixing with the fine powder and the collision against the collision plate by the pressure air flow are repeated. The purpose is to make the base particles encapsulated by the fine powder.

The second invention relates to an apparatus for carrying out the upward method, and includes a hopper for supplying mother particles and fine powder to be attached and coated thereto, and a stirring device for mixing and stirring the mother particles and fine powder supplied from the hopper. The air flow pump is connected to the stirrer through a delivery passage, and the discharge passage of the air flow pump communicates with the stirrer, and a collision plate is provided at a suitable position in the discharge passage to prevent the mother particles and fine powder from being removed by the stirrer. The process involves repeating the process of adhering the fine powder to the surface of the base particles by mixing with the base particles, spraying the mixture of the base particles and the fine powder onto the collision plate using an air pump, and returning the mixture to the stirrer.

The agitator has a sufficient volume to store a predetermined amount of powder, and the delivery passage is equipped with a flow rate adjustment valve, which regulates the flow of powder, maintains the stirring time, and controls the air flow pump. It is preferable to regulate the amount of supply.

Further, it is preferable that the collision plate constitutes a switching valve attached to the discharge port, and acts as a collision plate when the valve is closed.

Furthermore, the stirrer may be equipped with a liquid injection nozzle.

[Effect]

The base particles and fine powder are mixed by a stirrer, and the fine powder is attached to the surface of the base particles. Then, the powder is collided with a collision plate together with pressurized air to embed the fine powder on the surface of the base particles. By repeating this process, the fine powder can be pressed onto the entire surface of the base particles.

〔Example〕

The figure shows an embodiment of the invention. In addition, FIG. 1 is an explanatory diagram of the operation, FIG. 2 is a longitudinal sectional view of the powder surface modification device 1, FIG. 3 is a plan view with the lid 3 removed, and FIG. 4 is an inside plan view of the lid. It is. This powder surface modification device 1 includes a casing 2 and a lid 3.

The housing 2 is provided with an agitator 4 and an airflow pump 5. The agitator 4 has, for example, a single blade 6 on each of the upper and lower sides.
a, 6b (hereinafter collectively referred to as stirring blades 6)
are arranged at intervals in the shape of a cross. A stirring chamber 7 formed in the housing 2 has a size that accommodates a predetermined amount of powder, and a drive shaft 8 is connected to a variable speed drive motor 9 (FIG. 1).

The airflow pump 5 is, for example, a centrifugal pump, and the drive shaft 10 is connected to a variable speed drive motor 11 (FIG. 1). In addition, an intake pipe 13 is attached to the pump chamber 12 of the airflow pump 5, and a discharge passage 15 is attached to the housing 2.
is formed tangentially, and its tip communicates with the stirring chamber 7.

Further, a collision plate 20 is provided oppositely to this discharge passage 15. In the illustrated example, two examples of the collision plates are used as shielding plates for a switching valve 21 and communicate with a discharge port 22. That is, when the collision plate 20 is in the illustrated position, the powder sent through the discharge passage 15 collides with the collision plate 20,
The powder is guided by the agitator 4 and rotated to the position indicated by the chain line, and the powder is guided from the discharge port 22 to a gas-fixed separator 23 such as a cyclone, as shown in FIG.

25 is a stirrer 4 and an air flow pump 5 on the top of the housing 2.
It is a guide plate attached between the air flow pump 5 and the air flow pump 5. One end is in contact with the stirring chamber 7, and the other end extends to the vicinity of the center of the air flow pump 5.

Further, 26 is a jacket formed in the housing 2 as necessary to supply hot or cold water, and is a jacket for supplying hot water or cold water to the stirring chamber 7.
and the pump chamber 12 is heated or cooled. 27 and 28 are an injection pipe and a discharge pipe, respectively.

Furthermore, 30 is a liquid injection nozzle provided as necessary, and is provided to open into the stirring chamber 7.

Further, a powder supply port 40 for supplying powder to the agitator 4 is formed in the housing 3, and this powder supply port 40
is supplied to the hopper 4 via a supply pipe 41 as shown in FIG.
It is connected to 2. 43 is an on-off valve provided at the bottom of the hopper. This supply pipe 41 is also connected with a delivery air supply pipe 44 .

As shown in FIG. 4, the lid body 3 is provided with a concave groove 45 that sandwiches the guide plate 25 attached to the housing 2, and a delivery passage 46 is provided between the top surface of the guide plate 25 and the guide plate 25.
A flow rate regulating valve 47 is provided in the passage 46. Although this valve 47 is shown as a manually operated valve in the illustrated example, it can of course be a remotely operated valve that uses electromagnetic force, hydraulic pressure, or the like.

In addition, in FIG. 1, 50 and 51 are a gas concentration meter and a thermometer provided in the powder supply pipe 41, respectively.

Examples of powders (base particles) that can be applied to the present invention include pharmaceuticals, foods, fine chemical powders, cosmetics, dyes, printing inks, toners, ceramics, powder metallurgy, catalysts, electronic materials, biochemical powders, and interfaces. Various powders such as activators, etc., preferably have a particle size of 100 μm or less. Further, it is preferable that the particle surface has irregularities or grooves to facilitate the attachment of the fine particles to be attached, but the particle surface is not necessarily limited to this.

The procedure for surface modification of the base particles in the above configuration will be explained based on FIG. 1.

First, predetermined amounts of the base particles and the fine powder to be attached are charged into the hopper 42, either separately or in a mixed manner, and then supplied to the stirrer 4 together with conveying air from the air supply pipe 44. In this case, the flow rate adjustment valve 4
7, the delivery passage 46 is closed. After the above-mentioned supply, the stirrer 4 is operated to stir the supplied powder and make the fine powder adhere to the surface of the mother particles.

After stirring for a predetermined time, the flow rate regulating valve 47 is opened, and the mixed powder is supplied to the air flow pump 5 while regulating the flow rate. The airflow pump 5 sends out the air at high speed by centrifugal force, and the airflow pump 5 sends out the air at high speed through the discharge passage 15 to the collision plate 2.
Hit 0.

As a result, the fine powder that had simply adhered to the surface of the base particle is bitten into the surface of the base particle and is pressed. In this case, loose fine powder is also sent out at the same time, and a part of it is pressed against the base particles on the collision surface.

Next, the mother particles with the fine powder pressed onto a part of their surfaces and the free fine powder are fed into the stirrer 4 and stirred again, so that the fine powder is attached to the surface of the mother particles. I will send this back below.

The above processing time is stored in the computer in advance, and after a predetermined time has elapsed, the switching valve 21 is rotated, the collision plate 20 is moved to the chain line position, and the mother particles and free fine powder are transferred to the separator 23. It is separated from the conveying air and discharged downward.

The intake pipe 13 provided opposite to the airflow pump 5 is used to introduce outside air when a sufficient flow rate cannot be obtained during rotation of the airflow pump 5 and during the above-mentioned exhaustion. Further, it may be preferable to soften the base particles and fine powder by heating. In this case, hot water or steam is supplied to the jacket 26 to control the inside of the housing to a desired temperature. This allows the fine powder to be easily bitten into the surface of the base material upon collision. Temperature control in this case is performed by a temperature sensor, although not shown.

Alternatively, the hopper 42 may be provided with a heating means to heat the powder, particularly the base particles, or heated air may be supplied from the air supply pipe 44. The temperature in this case is measured by a thermometer 51.

Furthermore, depending on the surface condition of the base particles or the properties of the fine powder, it may be preferable to apply a temperature. In this case, water vapor, water, or a suitable solvent is injected into the stirrer 4 in the form of a spray from the liquid injection nozzle 30. This makes it easy to attach the fine powder to the base particles.

〔Effect of the invention〕

According to the present invention, the base particles and fine powder are stirred by a stirrer, the fine powder is attached to the base particle surface, and then the fine powder is applied to the base particle surface by colliding with a collision plate with a flow of pressurized air. By pressing and repeating this process, the entire surface of the base particle can be tightly covered with the fine powder.

In particular, according to the present invention, the steps of mixing the base particles and the fine powder and adhering the fine powder to the base particles are performed using a stirrer, and then the step of crimping and coating the base particles with the fine powder is performed by blowing the fine powder onto the collision plate using a pressurized air flow. Since both steps are carried out separately, such as by dipping, the fine powder can be adhered to the base particles uniformly and reliably, and the fine powder can be pressure-coated onto the base particles effectively.

Further, when using the apparatus of the present invention, a stirrer and an airflow pump are provided in one housing, a collision plate is provided on the discharge side of the airflow pump, and the above-mentioned base particles and fine powder are mixed and deposited by the agitator, Next, a mixed powder of base particles and fine powder is blown onto the collision plate by a pressurized air flow, and the collision causes compression bonding, and this process is repeated by circulating the mixture. It is possible to omit a means for mixing the powder and the fine powder, and it is also possible to uniformly adhere the fine powder to the base particles and reliably cover the base particles with the fine powder.

Furthermore, since the agitator is provided with a sufficient volume to store a predetermined amount of powder, and a flow rate regulating valve is provided in the delivery passage to regulate the delivery, processing can be performed as a so-called batch method.

Further, by forming the collision plate as a switching valve provided at the exhaust port, it is possible to easily switch between the collision action and the discharge action by opening and closing the valve.

Furthermore, by providing a liquid jet nozzle opposite to the stirrer, moisture can be applied and the fine powder can be effectively attached to the base particles.

[Brief explanation of drawings]

The figures relate to embodiments of the present invention; FIG. 1 is an explanatory diagram of the operation of the present invention, FIG. 2 is a vertical cross-sectional view of the powder surface modification device, and FIG. 3 is a plan view of the casing with the lid removed. FIG. 4 is an inside plan view of the lid. 1 is a powder surface modification device, 4 is an agitator, 5 is an airflow pump, 15 is a discharge passage, 20 is a collision plate, 21 is a switching valve, 22 is an outlet, 30 is a liquid injection nozzle,
42 is a hopper, 46 is a delivery passage, and 47 is a flow rate regulating valve.

Claims (1)

[Scope of Claims] 1. A stirrer that stirs a base particle and a fine powder to be impregnated and coated on the surface of the base particle to adhere the fine powder to the surface of the base particle; The attached base particles are sent to the air flow pump chamber via the delivery passage, and the base particles with the fine powder attached are collided with a collision plate by a pressurized air flow, and the fine powder is pressed against the base particles, and is returned to the agitator again. A method for modifying the surface of a powder, comprising repeating the mixing of the base particles and the fine powder and the collision of the base particles with the collision plate by the pressure air flow, so that the base particles are wrapped in the fine powder. 2. A hopper for supplying mother particles and fine powder to be attached and coated thereto, a stirrer for mixing and stirring the mother particles and fine powder supplied from the hopper, and a hopper connected to the stirrer via a delivery passage. Equipped with an air flow pump, the discharge passage of the air flow pump communicates with a stirrer, and a collision plate is provided at an appropriate position in the discharge passage to prevent adhesion of the fine powder to the surface of the mother particles due to mixing of the mother particles and fine powder by the stirrer. A powder surface modification device characterized in that the mother particles having the fine powder adhered thereto are repeatedly crimped onto the mother particles by blowing the fine powder onto a collision plate using an air flow pump, and refluxing the fine powder to a stirrer. 3. The agitator has a sufficient volume to store a predetermined amount of powder, and a flow rate adjustment valve is provided in the delivery passage.
3. The powder surface modification apparatus according to claim 2, wherein the valve regulates the flow of the powder, maintains the stirring time, and regulates the amount of supply to the air pump. 4. The powder surface modification device according to claim 2, wherein the collision plate constitutes a switching valve attached to the discharge port, and acts as a collision plate when the valve is closed. 5. The powder surface modification device according to claim 2, wherein the agitator is equipped with a liquid jet nozzle.