JPH10310802A - Continuous production equipment for film-coated powder - Google Patents

Abstract

(57) [Problem] To provide an apparatus capable of continuously producing a large amount of powder having a uniform thickness on a surface of the powder and having a plurality of layers of metal oxide films with good reproducibility. A supply pipe for supplying a powder suspension to be coated, a supply pipe for introducing a solution of a hydrolyzable metal compound, and a supply pipe for an inert gas mixture of a hydrolyzing agent are provided. A reaction tank comprising a stirrer having a stirring blade and a high-speed stirrer, a reaction tank for uniformly forming a metal oxide film or a metal film on the powder surface by hydrolysis of the hydrolyzable metal compound, and a powder coated film. Tank, a dryer for the film-coated powder, and a heat treatment machine, and at least one of the reaction tank and the washing tank is provided with a plurality of outlets for the upper solution on a side wall thereof. A continuous apparatus for producing a film-coated powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for continuously producing a powder having a metal oxide film and / or a metal film in a single layer or a multilayer on the surface of the powder, and particularly to a color magnetic toner and a color magnetic ink. Colored powder that can be used for
The present invention relates to a continuous production apparatus capable of producing a large amount of powder having high whiteness that can be widely used in other fields.

[0002]

2. Description of the Related Art First, the present inventor disperses a metal powder or a metal oxide powder in a metal alkoxide solution and hydrolyzes the metal alkoxide to form a first metal on the surface of the core particles. Disclosed is a method of forming an oxide film, and further forming a metal oxide film different from the first metal oxide film on the metal oxide film by the same film forming technique. (JP-A-6-228604). Further, the present inventor further improved the powder having the multilayer metal oxide coating, not only the metal oxide coating, a multilayer coating having a plurality of metal oxide coatings and metal coatings alternately. We have also invented a powder having
-90310).

In the above invention, the present inventors used a magnetic powder such as ferrite or chromium oxide as a core powder, formed a metal oxide coating film on the surface of the magnetic powder, and It has been disclosed that a sufficiently white magnetic powder can be obtained by forming a coating film of metallic cobalt or metallic silver. Furthermore, the present inventors obtain an insulating powder having good thermal conductivity by providing a metal oxide film on a metal powder having good thermal conductivity such as metallic silver or metallic copper as a metal powder, A powder having high functionality was developed by alternately providing a plurality of metal films and metal oxide films on the surface of a metal powder or a metal oxide powder (Japanese Patent Application Laid-Open No. 7-90310). Similarly, when forming a multilayer film of a metal oxide on the surface of a metal or metal compound powder, a more dense and stable metal oxide is obtained by heat-treating the powder coated with the metal oxide film in a multilayer. A powder having a multilayer film can be manufactured. In the multilayer film-coated powder, at least one layer of the multilayer film is a metal oxide film obtained by treating a metal salt with a weak alkaline aqueous solution and hydrolyzing the metal salt. Alternatively, a technology capable of manufacturing a powder having a multilayer film formed as a metal film has been developed.

Further, the present inventor has proposed an organic powder which can be widely applied to powders of materials other than metal powders or metal compound powders, for example, organic powders such as resin powders and glass powders. A technology has been developed that can provide multiple layers of metal films and metal oxide films on glass and glass powder. With the technology developed in this way, powders used in dry color toners for carrier-free one-component development used in electrophotographic copiers, etc., especially in electrophotography etc., images with higher resolution and higher contrast And a powder having a small particle size and a high whiteness can be obtained.

[0005]

The technical reasons why the highly functional metal film or metal compound film-coated powder can be produced by the above-described series of techniques are as follows: metal powder, metal compound powder, metal powder, and the like. Oxide powder, glass powder, magnetic metal powder, organic polymer powder, etc., can form a uniform and dense metal oxide film on the surface of various powders. This is also because a metal oxide film can be formed in a plurality of layers. Thus, it is possible to form a dense metal oxide film having a uniform thickness on the surface of various powders, by dispersing the powders in dehydrated alcohol or a mixture of alcohol and water,
While sufficiently stirring, a solution of a hydrolyzable metal compound such as a metal alkoxide or a metal salt used for forming a coating film is added, and a liquid mixture such as a mixture of alcohol and water or a weakly alkaline aqueous solution is gradually added to the homogeneous mixture. A liquid containing an agent or a hydrolyzing agent is added to hydrolyze a hydrolyzable metal compound such as the metal alkoxide on the surface of the powder to generate a metal hydroxide or the like on the surface of the powder, and the resulting metal It is based on a technique of gelling a hydroxide or the like and forming a film. The layer of gel such as metal hydroxide generated on the powder surface obtained by this technology is uniform and dense, and the metal oxide coating film generated on the powder surface derived from it is This is because the thickness is uniform and dense.

As described above, the surface of not only metal and metal oxide but also powders of various materials, such as organic powders and glass powders, is coated with a plurality of metal oxide coating films or metal coatings. The method for forming the film has already been described in the above-mentioned publication, and very good reproducibility has been obtained in a laboratory scale or small-scale production, but the thickness is uniform in practical use. It is not technically easy to industrially mass-produce a dense coating film on the surface of the powder in a multilayer, uniform and reproducible manner. In actual mass production, in order to form a uniform film, it is necessary to make the hydrolysis reaction uniform, and to separate the powder with the film formed from the reaction solution. It is naturally expected that there are various problems such as how to do it or how to sufficiently prevent the binding of the powders when the powder having the film formed is sent to the dryer. . An object of the present invention is to disperse and suspend powders of various materials for forming the above-described metal oxide coating film or metal coating film in a reaction medium such as dehydrated alcohol, and sufficiently agitate the metal while sufficiently stirring. A solution of a hydrolyzable metal compound such as an alkoxide and a hydrolyzing agent are added to form a metal oxide coating film or a metal coating film on the powder surface, and this operation is repeated to form a plurality of coating films. An object of the present invention is to provide a production apparatus capable of producing a large amount of powder having high reproducibility.

[0007]

The above objects of the present invention have been attained by the following means. (1) a supply pipe for a suspension in which the powder to be coated is uniformly dispersed,
A supply pipe for introducing a solution of a hydrolyzable metal compound, a supply pipe for an inert gas mixture of a hydrolyzing agent, and a stirrer having an irrigated stirring blade and a high-speed stirrer inside the tank; A reaction tank for uniformly forming a metal oxide film or a metal film on the powder surface by hydrolysis of a reactive metal compound, a washing tank for washing the powder coated with the film, and drying of the film-coated powder And a heat treatment machine, wherein at least one of the reaction tank and the washing tank is provided with a plurality of outlets for the upper solution on the side wall thereof. (2) The apparatus for continuous production of film-coated powder according to (1), wherein the reaction tank also serves as the washing tank. (3) The powder to be coated is supplied from a quantitative supply device to a supply pipe of a suspension in which the powder to be coated is uniformly dispersed, and a solvent is supplied and stirred to uniformly disperse the powder to be coated. (1) or (2), wherein a powder feeder for forming a suspension is formed, and the suspension of the powder to be coated is introduced into the reaction tank through the supply pipe. A continuous production apparatus for the film-coated powder according to the above.

(4) A supply pipe for the inert gas mixture of the hydrolyzing agent provided in the reaction tank, and a central pipe having a predetermined amount of the gaseous hydrolyzing agent or (1) to (3), characterized in that the outer tube is a double tube through which an inert gas is passed through which the agent mist passes.
The continuous production apparatus for a film-coated powder according to any one of the above. (5) In any one of the above (1) to (4), in the reaction tank and the washing tank, a plurality of washing liquid supply ports are provided at a level above the level of the liquid in the tank. Continuous production equipment for film-coated powder. (6) In the continuous production apparatus, a device for dissolving a hydrolyzable metal compound, an alcohol-based neutralization tank for neutralizing alcohol or an aqueous-based neutralization tank for neutralizing water, an alcohol recovery apparatus, a recovered alcohol storage tank, and powder. The continuous apparatus for producing a film-coated powder according to any one of the above (1) to (5), wherein a transfer device is provided as an accessory device.

(7) The method according to any of (1) to (6), wherein the hydrolyzing agent supplied from the hydrolyzing agent supply pipe is alcohol, water, a mixture of alcohol and water, or ammonia gas. The continuous production apparatus for a film-coated powder according to claim 1. (8) The film-coated powder according to any one of (1) to (7), wherein the hydrolyzable metal compound supplied from the hydrolyzable metal compound supply pipe is a metal alkoxide. Continuous production equipment. (9) The heat treatment machine heats and heats the dried film-coated powder stored in a sample container comprising a lid and a main body, and the sample container is provided at the center of the lid. The continuity of the film-coated powder according to any one of (1) to (8), wherein the sample is provided with a mesh through which a sample does not pass, and the lid is a sample container bolted to a container body. Manufacturing equipment. (10) At a stage before the powder to be coated is charged into the reaction tank, a detector is provided for detecting a change in characteristics of the powder to be coated when a coating film type is switched as a signal change, and a change in characteristics from the detector is provided. The continuous apparatus for producing a film-coated powder according to the above (1) or (2), further comprising a control device for instructing a change in conditions for supplying various raw materials by a signal.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is suitable for continuously producing a multi-layer film-coated powder. Which can also be used. Hereinafter, a description will be given of a manufacturing procedure for manufacturing a single-layer film-coated powder or a method for continuously manufacturing a multi-layer film-coated powder, and a combination of a single-function manufacturing apparatus and a single-function manufacturing apparatus necessary for the manufacturing thereof . The single-function manufacturing apparatus of the film-coated powder of the present invention, and the combination of the single-function manufacturing apparatus are described below, whereby the manufacturing process described above can be adapted to the stage of mass production means, It has become possible to produce the single-layer or multi-layer film-coated powder of the present invention in large quantities and continuously.

FIG. 9 is a block flow sheet showing a typical embodiment of the production process of the present invention, which is carried out in a large-scale continuous apparatus of the powder coated with a multilayer film. In FIG. 9, the device is shown as a device having a required function, not a specific structure, because it is shown with a basic concept. In FIG. 9, a powder feeding device 61 for feeding a slurry of a powder or a powder and a solvent that dissolves a hydrolyzable metal compound, a metal oxide powder is added to the powder (or a film-coated powder in the case of a multilayer coating). Reaction tank 62 for coating the coating film, cleaning tank 6 for cleaning the film-coated powder
3. A combination of a manufacturing apparatus including a drying apparatus 64 for drying the film-coated powder and a heat treatment apparatus 65 for heat treatment is illustrated. Further, as an example of a preferred embodiment for continuous production, a device in which a powder storage tank 66 and a control device 68 for controlling a process are connected to each other is arranged in front of the charging device 61 so that powder (or film coating) is provided. When the step of coating one layer of film on the (powder) is completed, the function provided by the control device 68 to switch to the next process condition is shown as a dotted block. By giving such a function to the manufacturing process, the conditions of the film forming apparatus can be automatically changed, and continuous manufacturing can be automatically performed. When the reaction tank 62 also serves as the washing tank 63, the washing tank 63 can be omitted.

FIG. 9 further shows, as additional equipment to the above-mentioned various equipment, an equipment for adding various raw materials necessary for the production (not shown), a solvent neutralization tank 69 (the solvent for dissolving the hydrolyzable metal compound is alcohol or When the solvent is a mixed solvent of alcohol and water, the alcohol-based neutralization tank 69 neutralizes the alcohol.
a, in the case of water, an aqueous neutralization tank 69b) for neutralizing water, an alcohol recovery device 71, a recovered alcohol storage tank 72, and a powder transfer path are shown.

Before individually describing the characteristic film coating apparatus, washing apparatus, drying apparatus and heat treatment machine used in the present invention, the continuous production of the multilayer coating film powder of the present invention according to the block flow sheet of FIG. The steps will be described. FIG.
First, a powder (usually a slurry in which the powder is dispersed in a solvent) is transferred from a powder input device 61 to a reaction tank 62. The reaction tank 62 is divided into two types according to the type of reaction, and the reaction tank 62a uses a metal alkoxide, which is a highly reactive hydrolyzable metal compound, with alcohol as a medium, water as a hydrolyzing agent, and powder. A reaction tank for forming a metal oxide coating film on the body surface. The reaction tank 62b uses a metal chloride which is a low-reactive hydrolyzable metal compound, and is made of water or a weakly alkaline aqueous solution (aqueous ammonia solution or mist thereof). Is a reaction tank for forming a metal oxide coating film, and in some cases, a metal coating film on the surface of the powder using the above method. Which of the reaction tanks forms the coating film is stored in the control device in advance, and as described later, for example, the powder storage tank 66 is used.
It is desirable that a powder meter 67 is attached to the apparatus, a signal is issued so as to switch the manufacturing conditions according to the remaining amount, and the control device is operated by the signal to automatically select and set the manufacturing conditions. Of course, selection and switching may be performed manually.

The powder whose surface is coated with the metal oxide film in each reaction tank precipitates in the reaction tank 62a or 62b to form a slurry, is sent to a washing tank 63, and is washed there. The supernatant in the reaction tank and the washing liquid in the washing tank 63 (the supernatant and the washing liquid are also referred to as the upper liquid) are a plurality of washing liquids opened on the inner surface of the reaction tank 62a or the inner surface of the reaction tank 62b described later. It is used to wash the reaction tank by flowing down the wall of the reaction tank from the mouth. Similarly, it is used to wash the cleaning tank 63 by flowing down from the plurality of cleaning ports opened on the inner surface of the cleaning tank 63 along the wall surface of the cleaning tank 63. The surplus cleaning liquid is sent to an alcohol neutralization tank 69a if the liquid is mainly composed of alcohol, and is sent to a water neutralization tank 69b if the liquid is mainly composed of water, to be neutralized. The neutralized alcohol-based liquid is sent to an alcohol recovery device 71, and the recovered alcohol is stored in a recovered alcohol storage tank 72.

The film-coated powder washed in the washing tank 63 is transferred to a drying device 64 and dried. The dried film-coated powder is heat-treated by the heat treatment device 65 and stabilized to be a metal oxide film-coated powder or a metal film-coated powder. In order to obtain a multilayer film-coated powder, the dried metal oxide film-coated powder or the metal film-coated powder (hereinafter abbreviated as metal oxide film-coated powder) is transferred to the powder input device 61 again. Then, a metal oxide film is formed under conditions different from those described above to obtain a multilayer metal oxide film-coated powder. At this time, in a preferred embodiment of the present invention, the remaining amount of the first raw material powder is measured by a powder meter 6.
7 and sends a signal to the control device 68 when the remaining amount is a predetermined amount (for example, zero), and the control device 68 controls the condition of the reaction tank 62 according to the signal in advance in correspondence with the surface reflection spectrum value of the powder. The controller 68 is operated using the measured value of the reflection spectrum as a signal, and the type and amount of the hydrolyzable metal compound supplied to the reaction tank 62, the mist of water supplied from the double pipe to the reaction tank 62, and the like. By changing the supply conditions of the raw materials such as the supply amount of ammonia, etc., and automatically changing the reaction conditions of the film-coated powder,
A multilayer-coated powder can be manufactured continuously. Of course, in the present invention, the manufacturing apparatus may be operated by manually setting the conditions of the reaction tank 42 without installing the reflection spectrum measuring apparatus.

Next, the main individual single-function devices of the present invention will be described below with reference to the drawings. The device shown in FIG.
Powder or slurry input device (hereinafter “powder input device”
2), a membrane coating device (referred to as a film forming device or “reaction tank”) and a washing device.
Is a schematic diagram showing a mode in which upper liquid outlets in a reaction tank are provided in multiple stages, the device shown in FIG. 3 is a schematic diagram showing a stirring device inside the reaction tank, and the device shown in FIG. FIG. 5 shows a state in which a liquid containing powder from a washing tank is concentrated and a solvent vapor is recovered from a dryer. The apparatus shown in FIG. 5 is a spray drying apparatus (an example of a “drying apparatus”). And a classifier, a sieve, and a container for powder heat treatment mounted on a weighing machine. The device shown in FIG. 6 is a heat treatment furnace (an example of a “heat treatment device”), which is arranged in this order. When a single-layer film-coated powder is produced and this step is repeated, a multi-layer film-coated powder can be produced.

In the film coating apparatus used in the present invention, when a metal oxide coating film is formed on the powder surface using a metal alkoxide which is a highly reactive hydrolyzable metal compound and alcohol as a medium, Alternatively, there are two modes in which a metal oxide coating film is formed on the powder surface using water as a medium using a metal chloride or the like, which is a low-hydrolyzable metal compound, and using an alkaline catalyst. . In the block flow sheet of FIG. 9, the former is a metal oxide film alcohol-based reaction tank, and the latter is a metal film water-based reaction tank. If the continuous manufacturing apparatus shown in FIG. 9 is used, a multilayer coating film powder having both a metal oxide coating film and a metal coating film can be manufactured continuously.

FIG. 1 shows a specific apparatus used when a metal oxide coating film is formed on the powder surface using a metal alkoxide and an alcohol as a medium in the film coating apparatus of the present invention. The step of coating the powder surface with a film according to the present invention will be described below with reference to FIG. In FIG. 1, a slurry is prepared by mixing powder and a solvent,
1 shows a combination of a powder feeding machine 1 for charging a metal oxide film, a reaction tank 2 for forming a metal oxide film on the powder surface, and a washing machine 3 for cleaning the metal oxide film-coated powder. First, in the powder charging machine 1 for preparing a slurry of powder to be charged into the reaction tank 2, the solvent 7 is contained in the powder charging machine 1.
(For example, alcohol, preferably ethyl alcohol), and the powder 9 is fed from the feeder 8. As the feeder 8, a fixed amount of powder is fed into a premixer (continuous type) or a high-speed stirrer by a fixed-rate feeder such as a fixed-rate hopper or a vibration feeder so that the powder can be mixed with the solvent. The powder 9 is dispersed in the solvent 7 in the powder input device 1 by the stirrer 6 to form a slurry. The valve is opened, and the slurry in the powder input device 1 is transferred by the supply pipe 10 into the reaction tank 2 provided with the stirrer 11.

Next, in the reaction tank 2 for forming a metal oxide coating film on the surface of the powder, the slurry is transferred from the powder charging machine 1 into the reaction tank 2 and the solution placed in the reaction tank 2 A hydrolyzable metal compound solution 13 (a solution in which a metal alkoxide is dissolved in ethyl alcohol) is supplied from a supply pipe 12, and a hydrolyzing agent ( (Gaseous) 15 is added together with an inert carrier gas to hydrolyze the hydrolyzable metal compound to form a gel-like film made of metal hydroxide on the powder surface.

A double tube 14 provided at the upper part of the reaction tank 2
In the case of a misted hydrolyzing agent, a gaseous hydrolyzing agent 15 is added to the central tube of the double tube 14 together with an inert carrier gas so that the gaseous hydrolyzing agent does not cause clogging in the tube. It is preferable to make the passage so that the inert carrier gas 16 is passed through the outer tube. Further, the double pipe 14 which is a supply pipe for such a gaseous hydrolyzing agent enables the hydrolyzing agent to be exchanged, and is selected by, for example, a control device 68 activated by a signal from the powder meter 67. Gaseous hydrolyzing agent is supplied. Similarly, an appropriate hydrolyzable metal compound solution 13 is supplied to the supply tube 12 by the controller 68 from the illustrated solution supply tube 12.

As described above, the powder,
When a hydrolyzable metal compound and a hydrolyzing agent coexist in a solvent and are reacted for a certain period of time with stirring, a gel-like film made of a metal hydroxide is formed on the surface of the powder. The gel film thus formed can be controlled by, for example, the amount of the hydrolyzing agent, and can be formed as a film having a constant thickness. In addition, in the another metal film water-based reaction tank (another film forming apparatus), when a metal chloride or water to which ammonia is added as a hydrolyzing agent is used instead of the metal alkoxide, powder or metal oxide-coated powder is used. A metal hydroxide gel-like film can be formed on the surface. In addition, the upper part of the reaction vessel 2 is usually filled with nitrogen gas 17,
An inert atmosphere is formed.

As shown in FIG. 3, the reaction vessel 2 is provided therein with a stirrer 22 having squid-type stirring blades and a high-speed stirrer 23 rotating at high speed. The stirrer 22 is
Since the squid-type stirring blade having a shape contacting the inner wall of the reaction tank 2 rotates at a low speed in contact with the inner wall of the reaction tank 2, the reaction is performed while preventing precipitation of powder. At that time, a laminar flow is generated inside the tank, and the powder is rotated together with the rotation of the stirring blade, but at the same time, the powder also settles.
The stirring blades rotate in contact with the bottom so as to prevent the powder from settling, thereby acting to scoop up the settled powder particles. In addition, the rotation of the stirring blade can prevent the film-coated particles from adhering to the wall surface. As described above, the wall of the reaction tank 2 is in contact therewith, and the squirrel-type stirring blades rotate.
It is preferable to use abrasion resistant polytetrafluoroethylene. The high-speed stirrer 23 rotates at a high speed so that the reaction between the metal alkoxide and the like and the hydrolyzing agent is uniformly performed in the reaction tank 2. When chloride or sulfate is used as a reaction raw material, the wall surface of the reaction tank is preferably made of an acid-resistant metal material or coated with an acid-resistant resin such as polytetrafluoroethylene.

Further, the reaction tank 2 is provided with a plurality of outlets 21 on its side wall for taking out an upper solution (hereinafter referred to as "the solution above the solution when the stirring is stopped after the completion of the reaction and left standing"). It is. This is because, in the reaction for coating the film in the reaction tank 2, the height at which the film-coated particles are floating in the liquid at the end of the reaction differs depending on the particle size of the final product. When processing the particles by
It is necessary to provide outlets 21 corresponding to the different heights in several stages. As described above, when the squid-type stirring blade is rotated at a low speed in the reaction tank 2,
The particles are classified by gradually settling while preventing precipitation of the particles forming the film. In addition, depending on the product, when particles having a certain degree of particle size distribution are formed, further, solid phase particles are formed without a part of the metal hydroxide generated by the hydrolysis affecting the film formation. In such a case, the particles can be separated by classification, and the classified particles can be used for respective applications according to the particle size.

For example, a final product having a particle size of 1 to 5 μm can be used for toner, a product having a particle size of 0.5 to 1 μm can be used for ink, and a product having a particle size of 5 to 30 μm can be used for cosmetics. Also, should the solid phase particles of the metal oxide be generated, since the particle size is small and the sedimentation speed is the slowest,
After sedimentation of the membrane-coated particles, the particles are taken out together with the upper solution, dried, and used as a metal oxide powder. As described above, in the classification, the above-mentioned squid-type stirring blades are slowly rotated and stirred so that the particles do not settle on the bottom surface, so that the membrane-coated particles are concentrated on the upper portion by a difference in sedimentation speed, and further classified. can do. At the same time, it is possible to prevent the reaction tank 2 from sticking at the bottom of the vessel. When the discharge ports are provided in multiple stages, the classification of the particles can be performed better by selecting the time and position of the discharge from the discharge ports.

In the reaction in the reaction tank 2, even if solid particles of metal oxide are not formed, unreacted raw materials remain in the liquid. At the time, take out as the upper solution, store it in the remaining liquid separate circuit,
By drying it, it can also be used as a metal oxide powder. Further, as shown in FIG. 1, a washing tank 3 is provided next to the reaction tank 2, and after the reaction in the reaction tank 2 is completed,
When the sedimented and concentrated membrane-coated particles are sent to the washing tank 3, where the membrane-coated particles are washed, the washing tank 3 can be provided with multiple outlets 21 on its side wall for taking out the upper liquid. . When the cleaning is performed by supplying the cleaning liquid from the cleaning liquid opening after the reaction in the reaction tank 2, the cleaning tank 3 may be omitted.

In FIG. 1, as described above, a washing tank 3 is provided below the reaction tank 2 (corresponding to the reaction tank 62 of the film forming apparatus in FIG. 9). The powder (or powder coated with metal oxide) having the metal hydroxide gel film produced in the tank 2 is washed with alcohol or water. In some cases, it may be washed with a mixed solution of alcohol and water. When transferring the slurry-like powder from the reaction tank 2 to the washing tank 3, it is preferable to transfer the powder using a slurry pump so that the slurry does not adhere to the transfer pipe. At this time, it is preferable to transfer the slurry while continuing stirring so that the slurry does not stay in the reaction tank 2. In the case where cleaning of the powder is not required, a drying device may be provided in this portion (the portion where the cleaning tank 3 is provided) to dry the coated powder. The cleaning liquid in the reaction tank 2 and the cleaning tank 3 is carried to the cleaning opening 20 through the cleaning liquid supply pipe 19, and the inner walls of the reaction tank 2 and the cleaning tank 3 are cleaned by the upper liquid 18 flowing out of the cleaning opening 20. . Deposits on the blades and walls after the reaction in the reaction tank 2 can be easily dropped by attaching a solvent injection nozzle to a part or the upper part of the cleaning opening of the container and injecting the solvent with pressure to prevent contamination to the next reaction. be able to.

As shown in FIG. 2, the reaction tank 2 has a side wall.
Is provided with multiple take-out ports 21.
P for tube for mouth 21₁, P_Two, P_Three, P_FourIndicates that
For example, take-out pipe P₁The liquid level when opening is L₁That
Will be. And each pipe P ₁, P_Two, P_Three, P_FourTo
Accordingly, the liquid level is L₁, L_Two, L_Three, L_FourCan be set
Can be. Then, the stirrer 22 is operated in the reaction tank 2.
The particles that have formed a film by rotating them
Since the particles are classified at the position corresponding to the particle size,
Since there are small particles,
The particles become coarser as they come down. This thing
After washing after the reaction is completed, for example, take out pipe P₁To
Open the liquid level L₁To remove fine particles
And then take out pipe P_TwoTo remove relatively fine particles.
And finally take out pipe P_FourTo remove the coarse particles
To separate the classified particles.
You.

FIGS. 2 and 3 show the relationship between the liquid level at the outlet of the reaction tank 2 and the positional relationship between the stirrer 22 and the high-speed stirrer 23. In this reaction tank 2, after taking out the liquid containing the classified particles from each take-out pipe, the last remaining liquid (reaction residual liquid) 24 is taken out from the reaction tank 2, and as shown in FIG. The mixture is concentrated by distillation under reduced pressure, and the concentrated liquid 26, which is a residual liquid after distillation, is led to a dryer 27 and dried to obtain a powder. This powder is a powder of an oxide such as titania or silica produced as a by-product from the reaction raw material, and the obtained powder becomes a pigment, a secondary raw material of a toner, and also a cosmetic. The vapor 29 of the solvent exiting from the concentrator 25 and the dryer 27 is led to a condenser 30 where it is cooled and condensed into a liquid, which is returned to a distillation apparatus or recovered and used again as a solvent for the raw material. This dryer 27 corresponds to the drying device 64 shown in FIG.

A description will be given of a case where the washed coated powder is dried into a metal oxide film-coated powder by using, for example, the spray dryer 4 shown in FIG. 5 as one type of the drying device 64. FIG. 5 shows a pneumatic spray dryer 4 most commonly used in the present invention. In the pneumatic spray dryer 4, a powder having the metal hydroxide gel-like film or a metal oxide-coated powder (hereinafter sometimes simply referred to as “powder”) is supplied to the upper nozzle 31 in a slurry state, Drying is performed by ejecting the air from the nozzle 31 into the spray dryer 4 together with dry air. When transferring the slurry-like powder from the washing device 3 to the drying device, it is preferable that the slurry-like powder is transferred while the stirring of the slurry-like powder is continued in the washing device 3.

The dried powder is supplied to cyclone 32 in the next step.
And classify it here. The classified dry powder is sieved with a mesh, and the powder having the adjusted particle size is stored from a popper 33 into a sample container 34 (a heat treatment container) placed on a weighing machine 35. Transfer to the next heat treatment furnace. In addition, the dried powder may be stored in the sample container 34 via the fixed amount supply device (hopper 33) as shown in FIG. 5, or may be stored directly in the sample container 34. However, at this time, the weight of the dry powder stored in the sample container 34 is
It is preferable that the weight of the dried powder weighed and stored in step 5 is kept constant so that unevenness in baking does not occur when heat treatment is performed in a heat treatment furnace. In addition, when the dry powder is stored in the sample container 34 and heat-treated in a heat treatment furnace, in order to crush the dry powder in the sample container 34, one to three different sizes of crushing media are used. It is desirable to store it together with the dry powder. It is preferable that the crushing medium is also weighed and stored by the weighing hopper 33 so that baking unevenness does not occur when heat-treated.

In order to make the powder coated with the multilayer film of the present invention into a colored magnetic toner or a colored magnetic ink which has good color saturation and excellent resolution, it is necessary to use 30 powders.
0 ° C to 1000 ° C, preferably 400 ° C to 700 ° C
The heat treatment is preferably performed at a temperature within the range described above. For this purpose, it is preferred that the multilayer-coated powder of the present invention be dried and then heat-treated while being crushed if necessary. Therefore, 3
As a preferable heat treatment furnace (in a continuous production apparatus) of the multilayer film powder of the present invention at a high temperature in the range of 00 ° C. to 1000 ° C., the heat treatment is performed by sending the powder to a rotary tube furnace shown in FIG. preferable. Further, as described above, it is preferable that the crushing medium is stored together with the powder in the sample container storing the dry powder, and the powder is crushed during the heat treatment.

FIG. 6 shows the details of the structure of the sample container 34 used for storing the powder and the crushing medium in the heat treatment furnace shown in FIG. 8 and performing the heat treatment while crushing the powder. Although shown in an exploded state in FIG. 6, from above, a sample container 34 provided with a bolt 37 for fixing the lid 36 to the sample container main body 35 and a mesh 38 at the center thereof for preventing powder from flowing out. An example (plan view) of a lid 36, a sample container main body 35 having a bolt hole and a ring 39 at the center thereof for fixing the lid 34 thereon, and a ring 39 below the lid 36 is shown. As can be understood from FIG. 6, two or more upper portions of the sample container 34 are female holes for bolts, holes corresponding to the holes are also opened in the lid 36, and a ring 39 also having a corresponding hole is fitted. These are closed with bolts 37 from outside. The sample container body 35 of the sample container 34 shown in FIG.
9 is fitted. An exhaust port is opened in the center of the lid 36 of the sample container 34, and a wire mesh (mesh) 38 having a finer mesh than preferably 300 mesh is attached to prevent the powder from flowing out.

The cyclone 32 shown in FIG.
After the powder and the crushing medium are quantitatively stored in the sample container 34 through Step 3, the lid 36 of the sample container is closed, and the sample container is moved into the heat treatment furnace by a roller accumulator type conveyor or the like. A guide is attached at the end of the conveyor, and the guide is used to place the sample container 34 sideways so that the opening with the lid 36 faces the exhaust side, and place the sample container 34 in the heat treatment furnace. In FIG. 7, the ring 3
An aspect in which 9 is fixed to a sample container main body 34 having a female hole with a bolt 37 is shown in a cross-sectional view. From this figure,
Since the thickness (t + α) of the ring 39 is thicker than the thickness (t) of the head of the bolt 37, it can be seen that the head of the bolt does not touch the sample container body 34 even when the bolt 37 is closed.

FIG. 8 shows a heat treatment furnace 5 which can be preferably used for heat-treating the dried multilayer-coated powder of the present invention at a high temperature of 300 ° C. or more. The rotary tube furnace 42 in the heat treatment furnace 5 is isolated from the outside world by a shutter 52, and the shutter 52 of the preliminary insertion chamber 48 is opened and closed,
The atmosphere in the rotary tube furnace 42 in the furnace 5 is maintained. The reaction vessel 44 (the sample vessel 34) is inserted into the pre-chamber and the rotary tube furnace for heat treatment.
However, since the inner tube is rotating, the reaction vessel 44 is dropped into the rotating tube furnace 42 using the guide slope and gas pressure such as nitrogen gas. At this time, as described above, the reaction vessel 44 is placed in the heat treatment furnace 5 by laying the reaction vessel 44 sideways so that the opening having the lid 36 is on the exhaust side. Also,
After the heat treatment, the reaction tube 44 is pushed out of the reaction vessel 44 using gas pressure, and the reaction vessel 44 is transferred to the cooling chamber using the slope.

The processing there will be described in more detail with reference to FIG. In FIG. 8, heating elements 43 are attached to at least two places above and below the furnace 42,
(It can also be referred to as a “reaction chamber” 42) and is put into a reaction container 44 containing dried powder, nitrogen gas is passed through the reaction chamber 42, and the reaction chamber 42 is rotated by a motor 45 via a drive chain. Then, the sample is heated by a heating element 43 provided outside the reaction chamber 42, and the sample is heat-treated at a temperature in the range of 300 to 1000 ° C, preferably 400 to 700 ° C. The powder whose heat treatment has stabilized the metal oxide coating layer is supplied to the reaction chamber 4.
2 is drawn into a cooling chamber using a slope, and after cooling, the lid 36 of the reaction vessel 44 is opened, the powder is taken out of the reaction vessel 44 together with the crushing medium, and the crushing medium is sieved with a vibrating sieve to remove the powder. Separation is preferred. The powder requiring film formation is returned to the powder feeder 1 shown in FIG. 1, but the powder currently being formed is completely processed and the production conditions required for the next step are determined by a signal from the powder meter. It is better to do it after it is maintained. The powder, which has been subjected to the film coating into a predetermined layer configuration, is classified into a predetermined particle distribution and then packed in a bag.

In the continuous production process described above, when water vapor is absorbed into the solvent and the water content increases, it is impossible to control the film forming reaction (hydrolysis reaction). Also, if the powder absorbs moisture, the film formation reaction cannot be controlled anymore.
It is necessary to maintain the atmosphere at a constant temperature and humidity.

In order to automatically change the type of the powder coating film described in the above (10), a solvent to be supplied to the powder charging tank, a hydrolyzing agent to be supplied to the reaction tank, and hydrolysis The characteristics used to command the change of the solution of the reactive metal compound include the amount of the powder supplied in the previous stage, the amount of the film-coated powder completed in the previous stage, or the film completed in the previous stage. Examples include the surface reflection spectrum of the coated powder. Thus, by installing a control device operated by a signal obtained from the above or other characteristics, it is possible to selectively supply the various raw materials of the present invention and adjust the supply amount by adjusting a supply pump or a valve. It is possible to automatically and continuously produce a multilayer-coated powder. However, the above object of the present invention can also be achieved by the apparatus for continuously producing a multilayer film powder of the present invention by manually adjusting the type and amount of raw materials.

[0038]

The present invention will be described below in more detail with reference to examples. However, the present invention is not limited to only this embodiment. Example 1 In the block flow sheet shown in FIG. 9, when a metal oxide film alcohol-based reaction tank is used and a single layer of titanium dioxide film is coated on carbonyl iron powder by a method of recovering alcohol by an alcohol-based recovery step. Will be described.
BAS using the feeder 8 in the powder feeder 1 shown in FIG.
While feeding 20 kg of F carbonyl iron powder (average particle size: 1.8 μm), 40 kg of ethanol is fed from the side pipe and stirred by the stirrer 6 to form a slurry. The slurry is transferred from the supply pipe 10 to the reaction tank 2, and 6 kg of deionized water and 47.4 ethanol are used in the reaction tank 2 using dry nitrogen as a carrier gas.
kg of the mixed solution is mist-formed and sent through the double pipe 14. On the other hand, titanium ethoxide 4
of a solution dissolved in 118.7 kg of ethanol, and stirred at 25 ° C. while stirring with a stirrer 11 in a reaction vessel 2.
After reacting for a period of time, a coating film composed of a gel layer of titanium hydroxide was formed on the surface of the carbonyl iron powder.

The carbonyl iron powder on which the titanium hydroxide gel-like coating film is formed is separated by sedimentation, and the sedimented and separated carbonyl iron powder is ejected from the nozzle 31 of the spray dryer 4 shown in FIG. The carbonyl iron powder having the gel coating film of titanium hydroxide is dried. On the other hand, the reaction solution in the reaction tank 2 after sedimentation and separation of the carbonyl iron powder is sent to an alcohol-based neutralization tank shown in FIG. 9 and neutralized by adding a base. The alcohol is collected, the collected alcohol is stored in a collected alcohol storage tank, and if necessary, is sent to the powder input machine 1 as dehydrated alcohol and reused. The titanium oxide-coated carbonyl iron powder stabilized by heat treatment is crushed and classified if necessary, and shipped as a titanium oxide-coated carbonyl iron powder product having a predetermined particle size.

Example 2 (in the case of coating twice) As in the case of Example 1, the alcohol was recovered by the alcohol-based recovery step using a metal oxide film alcohol-based reaction tank in the block flow sheet of FIG. The following describes a case in which the carbonyl iron powder is coated with silica as the first layer and then with a titanium dioxide film as the second layer.

First layer: Silica coating BAS using the feeder 5 in the powder feeder 1 shown in FIG.
While 10 kg of carbonyl iron powder (average particle size: 1.8 μm) made by F is charged, 30 kg of ethanol is fed from the side tube and stirred by the stirrer 6 to form a slurry. The slurry is transferred to the reaction tank 2 and 8 kg of deionized water and 11 k of ammonia water (29% concentration) are supplied to the reaction tank 2 using dry nitrogen as a carrier gas.
The mixed solution composed of g is misted and sent through the double tube 14. On the other hand, silicon ethoxide 6 k
g of ethanol dissolved in 49.3 kg of ethanol.
The reaction was carried out at 25 ° C. for 6 hours while stirring with the stirrer 11 in the reaction tank 2 to form a coating film comprising a gel layer of silicon hydroxide on the surface of the carbonyl iron powder.

The carbonyl iron powder on which the gel coating film of silicon hydroxide is formed is separated by sedimentation. The carbonyl iron powder having the sedimented and separated gel coating film is passed through the nozzle 21 of the spray dryer 4 shown in FIG. The carbonyl iron powder having the gel coating film of the hydroxide of silicon is dried by being blown into the chamber of the dryer. After drying, heat treatment was performed at 650 ° C. for 30 minutes using a rotary tube furnace to obtain silica-coated powder A. After the heat treatment, 10 kg of the obtained silica-coated powder A was dispersed again in 39.7 kg of ethanol, and 3 kg of silicon ethoxide and ammonia water (29%
(Concentration) 5.5 kg, and the mixture was reacted for 5 hours while stirring, and subjected to vacuum drying and heat treatment in the same manner as the first time to obtain silica-coated powder B. Obtained silica-coated powder B
Had good dispersibility and each was a single particle.

Second layer: titanium oxide coating Next, the steps described in the block flow sheet of FIG. 9 will be described.
The weighing device 67 provided between them measures whether the carbonyl iron powder, which is the first raw material, has been used up, and operates the control device 68 in response to a signal from the powder weighing device 67 when there is no remaining amount. According to the method described above, the type of inert gas supplied to the double pipe 14 provided in the reaction tank 2 of FIG. Decomposable solution, the conditions required for the formation of a gel coating film of titanium hydroxide in the next step,
That is, deionized water using dry nitrogen as a carrier gas.
The conditions were changed so that a mist of a mixed solution consisting of 7 kg and 47.4 kg of ethanol was supplied to the double pipe 14, while titanium ethoxide 3.6 was supplied from the solution supply pipe 14.
The conditions are changed so that a solution in which kg is dissolved in 18.7 kg of ethanol is sent.

Accordingly, the silica-coated powder is supplied to the powder input device 1
47.4 kg of ethanol is fed from a side pipe while stirring using a feeder 8 and stirred by a stirrer 8 to form a slurry. When this slurry is transferred to the reaction tank 2, the reaction raw material is automatically supplied to the reaction tank 2 from the double pipe 14 and the solution supply pipe 12, and is stirred in the reaction tank 2 by the stirrer 11.
By reacting at 6 ° C. for 6 hours, a coating film composed of a gel layer of titanium hydroxide is formed on the surface of the silica-coated powder (silica-coated carbonyl iron powder).

The silica-coated powder (titanium hydroxide-coated silica-coated carbonyl iron powder) on which the gel coating film of titanium hydroxide is formed is separated by sedimentation, and the separated gel-coated silica-coated powder of titanium hydroxide is separated. B is ejected from the nozzle 31 of the spray dryer 4 shown in FIG. 5 into the interior of the dryer to dry the silica-coated powder having a gel coating film of titanium hydroxide. The thus-obtained two-layer film-coated carbonyl iron powder is dried and then heat-treated at 650 ° C. for 30 minutes using a rotary tube furnace 5 to obtain stabilized silica-titania powder (titanium oxide-coated carbonyl iron powder). I got Further, 9 kg of the silica / titania powder was immersed in 158.7 ethanol similarly to the first titania coating.
of titanium ethoxide, and further added 5.4 kg of deionized water and 47.000 ethanol.
After dropping 4 kg of the mixed solution over 30 minutes, 25 ° C.
For 5 hours, subjected to vacuum drying and heat treatment,
A stabilized silica-titania powder was obtained. The obtained silica-titania powder is crushed if necessary, classified, and shipped as a product having a predetermined particle size. The peak wavelength of the spectral reflection curve of this powder was 552 nm, the reflectance at the peak wavelength was 40%, and the powder was bright green.

[0046]

According to the production apparatus of the present invention, a multi-layer metal oxide film-coated powder or a multi-layer metal oxide film and a powder coated with a metal film can be continuously and mass-produced with good reproducibility. Can be manufactured. In particular, by using a magnetic powder as a powder, a large amount of colored powder that can be used for a color magnetic toner or a color magnetic ink can be produced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a part in which a powder feeding machine, a reaction tank, and a washing tank are combined in a manufacturing apparatus of the present invention.

FIG. 2 is an explanatory view of a portion of an outlet of a reaction tank in the production apparatus of the present invention.

FIG. 3 is an explanatory view showing the inside of a reaction tank in the production apparatus of the present invention.

FIG. 4 is an explanatory view of a part where a concentrator and a dryer are combined in the production apparatus of the present invention.

FIG. 5 is an explanatory view of a part where a spray dryer and a classifier are combined in the manufacturing apparatus of the present invention.

FIG. 6 is a view showing an overview of a main body and a lid of a sample container used for heat treatment of the powder coated with a multilayer metal oxide film of the present invention.

FIG. 7 is an explanatory view of a method of attaching a belt to a main body of a sample container used for the heat treatment of the present invention.

FIG. 8 is a view showing an overview of a rotary tube furnace used for heat treatment of a metal oxide film-coated powder in the production apparatus of the present invention.

FIG. 9 is a block flow sheet for explaining a process of producing a powder coated with a metal oxide film by the production apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Powder input machine 2 Reaction tank 3 Washing tank 4 Spray dryer 5 Heat treatment furnace 6 Stirrer 7 Solvent 8 Feeder 9 Powder 10 Supply pipe 11 Stirrer 12 Solution supply pipe 13 Hydrolyzable metal compound solution 14 Double pipe 15 Hydrolytic agent Mist + Inert gas 16 Inert gas 17 Nitrogen gas 18 Upper liquid 19 Cleaning liquid supply pipe 20 Cleaning opening 21 Outlet 22 Stirrer 23 High-speed stirrer 24 Reaction residue 25 Concentrator 26 Concentrate 27 Dryer 28 Powder 29 Vapor 30 Condenser 31 Nozzle 32 Cyclone 33 Hopper 34 Sample container 35 Meter 36 Lid 37 Bolt 38 Mesh 39 Ring 42 Reaction chamber 43 Heating element 44 Reaction vessel 45 Motor 46 Insertion rod 47 Gas sealed chamber 48 Insertion spare chamber 49 Extraction chamber 50 Gas supply Device 51 Vacuum pump 52 Shutter

Claims (10)

[Claims] 1. A supply tube for a suspension in which powder to be coated is uniformly dispersed, a supply tube for introducing a solution of a hydrolyzable metal compound, and a supply tube for an inert gas mixture of a hydrolyzing agent. A stirrer having a squid-type stirring blade inside and a high-speed stirrer, and a reaction tank for uniformly forming a metal oxide film or a metal film on the powder surface by hydrolysis of the hydrolyzable metal compound, A washing tank for washing the powder coated with the film, a dryer for the film-coated powder, a heat treatment machine, and at least one of the reaction tank and the washing tank has a multistage discharge port for the upper solution on the side wall thereof. An apparatus for continuously producing a film-coated powder, wherein the apparatus is provided. 2. The continuous production apparatus for a film-coated powder according to claim 1, wherein said reaction tank also serves as said washing tank. 3. The coating target powder is supplied from a constant-quantity supply device to a supply pipe of a suspension in which the coating target powder is uniformly dispersed, a solvent is supplied and agitated, and the coating target powder is uniformly mixed. A powder feeding machine for forming a dispersed suspension is connected, and the suspension of the powder to be coated is introduced into the reaction tank through the supply pipe. 2
A continuous production apparatus for the film-coated powder according to the above. 4. A supply pipe for an inert gas mixture of the hydrolyzing agent provided in the reaction tank, and a central pipe having a predetermined amount of a gaseous hydrolyzing agent or a hydrolyzing agent using an inert gas as a carrier medium. The continuous production apparatus of a film-coated powder according to any one of claims 1 to 3, wherein the apparatus comprises a double pipe through which mist passes and an inert gas passes through an outer pipe. 5. The reaction tank and the cleaning tank, wherein a plurality of cleaning liquid supply ports are provided at a level higher than a water level of the liquid in the tank. A continuous production apparatus for the film-coated powder according to the above. 6. The continuous production apparatus includes a device for dissolving a hydrolyzable metal compound, an alcohol-based neutralization tank for neutralizing alcohol or a water-based neutralization tank for neutralizing water, an alcohol recovery device, a recovered alcohol storage tank, and The apparatus for continuously producing a film-coated powder according to any one of claims 1 to 5, wherein a powder transfer device is provided as an accessory device. 7. The method according to claim 1, wherein the hydrolyzing agent supplied from the hydrolyzing agent supply pipe is alcohol, water, a mixture of alcohol and water, or ammonia gas. Item 15. A continuous production apparatus for a film-coated powder according to item 13. 8. The film-coated powder according to claim 1, wherein the hydrolyzable metal compound supplied from the hydrolyzable metal compound supply pipe is a metal alkoxide. Body continuous production equipment. 9. The heat treatment machine heats and heats the dried film-coated powder stored in a sample container comprising a lid and a main body, wherein the sample container is located at a central portion of the lid. The membrane-coated powder according to any one of claims 1 to 8, further comprising a mesh through which the sample does not pass, and wherein the lid is a sample container bolted to a container body. Continuous production equipment. 10. A detector for detecting, as a signal change, a characteristic change at the time of switching a coating film type of the coating target powder before the charging of the coating target powder into a reaction tank, 3. The continuous production apparatus of a film-coated powder according to claim 1, further comprising a control device for instructing a change in conditions for supplying various raw materials by a characteristic change signal.