JPH09299885A - Air current classifying device for manufacture of toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to set a correct classification point and thereby enable high accuracy classification by using at least, part of a raw material feed pipe, a classifying edge and an air intake edge formed of a resin molding composed mainly of polybenzoimidazole, in a classifying device for classifying a pulverized raw material by the centrifugal force of a curved air current. SOLUTION: An air current classifying device for classifying powder into a particle by an air current is equipped with knife edge-type classifying edges 17, 18 on a lateral wall 23 and a lower wall 25 respectively. In addition, a coanda block 26 is installed at the lower part of a raw material feed pipe 16 with an open part in a classifying chamber 32, and the knife edge-type air intake edge 19 is provided toward the lower part of a classifying chamber 32 in the upper block 27 of the classifying chamber 32. In this case, this inner wall face of the raw material feed pipe 16, the classifying edges 17, 18 and further, the outer wall face of the air intake edge 19 are formed in resin composed mainly of plastic polybenzoimidazole. Thus the lubricity of a streaming particle is improved and the wear resistance of these parts in enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airflow classifying device used for producing a toner for developing an electrostatic charge image by utilizing the Coanda effect. More specifically, the present invention relates to an airflow classifier for efficiently classifying a powder raw material containing 50 number% or more of particles having a weight average particle diameter of 20 μm or less, and particularly to a powder raw material having a weight average particle diameter of 8 μm or less. The particles having a predetermined particle size based on the difference between the Coanda effect, the inertial force according to the particle size of each particle in the powder, the centrifugal force, etc. can be efficiently classified. The present invention relates to an airflow classifier for efficiently classifying toner for electrostatic image development.

[0002]

2. Description of the Related Art Toner or colored resin powder used for image formation by electrophotography usually contains at least a binder resin and a colorant or magnetic powder. With such a toner, the electrostatic charge image formed on the latent image carrier is developed into a toner image, and then the image is transferred to a transfer material such as plain paper or a plastic film, and further,
The obtained transferred image is fixed by a fixing device such as heat fixing means, pressure roller fixing means, or heat pressure roller fixing means to form an image. Therefore, as the binder resin forming the toner, a resin having a characteristic of being plastically deformed when heat and / or pressure is applied is used. Further, the toner or the colored resin powder for toner used for the image formation as described above is currently a mixture mainly containing at least a binder resin and a colorant or a magnetic powder (and, if necessary, a third component). Is melted and kneaded, the melt-kneaded product is cooled to obtain a cooled product, the obtained cooled product is pulverized, and the pulverized product is further classified.

On the other hand, for classifying powders, various airflow classifiers and airflow classifying methods have been proposed. Among them, there are classifiers using rotary blades and classifiers having no moving parts. Among them, a classifier without a movable part includes a fixed wall centrifugal classifier and an inertial force classifier. As a classifier utilizing inertial force, Loffier F. and K. Maly: Symposi
um on Powder Technology D-2 (1981), the elbow jet classifier commercialized by Nippon Steel Mining Co., Ltd., and Okuda S. and Yasukuni J .: Proc. Inter. Symposi
A classifier exemplified by um on Powder Technology '81, 771 (1981) has been proposed.

FIG. 5 and FIG. 6 show cross-sectional views of a conventional airflow classifying apparatus utilizing inertial force. This airflow type classifier ejects the powder raw material at high speed into the classification area together with the airflow from a raw material supply pipe 116 having an opening that is opened in the classification area in the classification apparatus, and the powder in the ejected airflow is discharged. The body material is classified by the inertial force of the particles and the centrifugal force of the curved air flow due to the Coanda effect. That is, as shown in FIGS. 5 and 6, a Coanda block 126 is provided in the classification chamber 132 of the airflow classifier, and the Coanda block 126 is introduced to introduce the airflow whose angle intersects with the airflow to be jetted. The coarse powder and the fine powder are separated by the centrifugal force of the curved air stream flowing along the block 126, and the fine powder is classified by the classifying edges 117 and 118 having a thin tip.
Alternatively, the coarse powder, the medium powder, and the fine powder are classified. At this time, the tip positions of the classification edges 117 and 118 and the air intake edge 119 are adjusted, and the flow rate of the air flow for classification is adjusted accordingly, so that the classification point (that is, the boundary of the size of the classified particles and Point) was set at a predetermined position. Further, the tip position of the classification edge corresponding to the specific gravity of the powder raw material and the desired classification point is detected and moved, and the air flow is controlled so as to have a predetermined flow rate accordingly.

However, in recent years, as a need for a toner for developing an electrostatic image, it has been particularly required in recent years to melt the binder resin at a lower temperature from the viewpoint of energy saving. Therefore, the binder resin having a low melting temperature is required. Have been used. When the powder raw material containing such a resin is introduced into the air stream classifying apparatus as described above for classification, the raw material supply pipe 116 and the classification edges 117 and 11 are used.
The minute frictional heat or collision heat generated at 8 or the air inlet edge 119 causes a fused substance or an adhered substance at these portions. Then, during continuous operation, if these adhesion and peeling are repeated, coarse particles may be mixed into the classified product, and it may not be possible to obtain an accurate classified product. In some cases, particles having a size that should be included in another particle group are mixed into the particle group that must be. There is also a problem to be improved such as a decrease in classification accuracy.

In particular, the phenomenon of toner fusion is likely to occur at the raw material supply pipe 116, the classification edges 117 and 118, and the air intake edge 119, which are locations where the powder material for toner production comes into heavy contact during classification. In such a case,
Usually, the raw material supply pipe 116 and the classification edges 117 and 11
It has been considered that the material of No. 8 has a good slipperiness, for example, it is made of fluororesin, or the surface is coated with fluororesin. However, magnetic powder is sometimes contained in the powder material for toner production, and in such a case, a problem of abrasion occurs, and a member made of fluororesin or a member whose surface is coated with fluororesin has abrasion resistance. Inferior,
I couldn't use it. In particular, such a problem was remarkable in the classification for producing the electrostatic charge image developing toner used in a copying machine, a printer or the like. Therefore, it is desired to develop a classifying device that can satisfy both fusion resistance and wear resistance.

Generally, toners are required to have many different properties, and in order to obtain such required properties, not only the powder raw material used but also the properties of the toner are often influenced by the manufacturing method. For example, in a classification process for producing a toner, classified particle groups are required to have a sharp particle size distribution. Further, it is desired to efficiently and stably produce high-quality toner at low cost.

Further, in recent years, for example, as an energy saving measure for a copying machine, a soft binder such as wax is used as a binder resin of toner in order to fix a toner image on a transfer material by pressure, or a heat fixing method is used. Even in the case of, in order to increase the fixing speed or to fix at a low temperature with low power consumption required for fixing, a low glass transition point, or
Binder resins having a low softening point and a low melting point have been used for toners. When the powder raw material of the toner containing such a resin is introduced into the above-described conventional classifying device and classified, adhesion and fusion are particularly likely to occur in the classifying device.

Further, in recent years, in order to improve image quality in copying machines and printers, toner particles are gradually becoming finer. Generally, as the substance becomes finer, the action of interparticle force increases, but the same applies to resin particles and toner particles, and when the substance has a small size, the cohesiveness of the particles increases, and aggregates are likely to occur. Further, the mass difference between the particles also becomes smaller. When an external force such as an impact force or a frictional force at the time of classification acts on such an agglomerate, the particles are easily fused in the classifier. In particular, fusion is likely to occur at the tip of the classification edge, and if such a phenomenon occurs, the classification accuracy will deteriorate and the classifier will not operate in a stable state, so a stable, high-quality classified product can be obtained over a long period of time. Becomes difficult.

In particular, when a toner having a sharp particle size distribution is to be obtained from a powder raw material for producing a toner having a weight average particle diameter of 10 μm or less, a conventional apparatus causes a reduction in classification yield. Furthermore, the weight average particle size is 8μ.
When a toner having a sharp particle size distribution is to be obtained from a powder raw material for producing a toner having a particle size of m or less, it becomes more remarkable that the conventional apparatus causes a decrease in classification yield.
From this point of view, there is a demand for an airflow classifying apparatus for producing a toner for developing an electrostatic charge image, which classifies fine powder, particularly resin fine powder such as toner, stably and efficiently. In particular, an airflow type classifying device for stably and efficiently classifying a toner having a weight average particle diameter of 8 μm or less is desired.

[0011]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an air flow type classifying apparatus capable of producing an electrostatic charge image developing toner in which the above-mentioned various problems are solved. That is, an object of the present invention is to set an accurate classification point and hold it to enable more accurate classification, and electrostatic charge image development capable of efficiently producing powder having a fine particle size distribution. Air flow type classifying device for producing toner for use, in particular, by effectively preventing the fusion of the powder raw material and the wear of the members in the device, the fluctuation of the classification point in the device is suppressed,
An object of the present invention is to provide an air flow type classification device for producing a toner for developing an electrostatic charge image that enables stable classification.

Still another object of the present invention is to provide an air flow type classifying apparatus for producing a toner for developing an electrostatic charge image which does not cause deposits in the classifying apparatus even when operated for a long time. It is in. Further, an object of the present invention is that the weight average particle diameter is 1
An air flow that can efficiently obtain a toner for electrostatic image development having a sharp particle size distribution from a powder raw material for toner production having a particle size of 0 μm or less, particularly a powder raw material for toner production having a weight average particle size of 8 μm or less. The purpose is to provide a classifier.

[0013]

The above object is achieved by the present invention described below. That is, the present invention is an air flow type classification device for classifying a powder raw material for toner production by an air flow, which is provided with at least a Coanda block, individual wall blocks and a classification area formed by a plurality of classification edges. The powder raw material is jetted by an air flow flowing in a raw material supply pipe having an opening in the classifying device in the classification area, and the powder raw material in the jetted air flow is curved air flow due to the inertial force of the particles and the Coanda effect. In the airflow type classifying device for classifying into a plurality of particle groups having different particle sizes by the centrifugal force of, at least the specific gravity of the powder raw material, the target classification point and the raw material supply speed, the raw material supply pipe, the classification edge and the intake edge A part is a resin molded product whose main component is plastic-based polybenzimidazole, or a resin whose main component is plastic-based polybenzimidazole Air classifier, characterized by being constituted by a ring has been member.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The airflow classifying apparatus for producing toner according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a sectional view of a classifying device in the case of dividing into three parts as an example of the airflow type classifying device of the present invention, and FIG. 2 shows a perspective view thereof. As can be seen from these figures, the basic structure of the airflow type classification apparatus for toner production of the present invention is the same as the conventional one described above.

In FIGS. 1 and 2, the side walls are 22, 2
3 and 24, the lower wall has a shape shown by 25, and the side wall 23 and the lower wall 25 are provided with knife-edge type classification edges 17 and 18, respectively. 17 and 18, the classification zone of the classification chamber 32 is divided into three. A raw material supply pipe 16 having an opening in a classification chamber 32 is provided at a lower portion of the side wall 22, and a lower portion of the raw material supply pipe 16 is bent downward in a direction in which a bottom tangent line extends and is long. A Coanda block 26 that draws an elliptic arc is installed. The upper block 27 above the classification chamber 32 is provided with a knife-edge type air intake edge 19 toward the lower part of the classification chamber 32.
Further, at the upper part of the classification chamber 32, an intake pipe 1 opening to the classification chamber
4 and 15 are provided. Also, the air inlets 14 and 15
The first and second gas introduction adjusting means 20 and 21 such as dampers and the static pressure gauges 28 and 29 are provided in the.
The positions of the classification edges 17 and 18 depend on the type of powder raw material that is the raw material to be classified and the desired particle size.
It is adjusted appropriately by rotating the shafts 17a and 18a of the respective edges.

The bottoms of the classification chamber 32 are provided with discharge ports 11, 12 and 13 which are opened in the classification chamber 32 so as to correspond to the respective fractionation areas. A communication means such as a pipe is connected to the discharge ports 11, 12 and 13, and each of these communication means may be provided with an opening / closing means such as a valve means. The raw material supply pipe 16 is composed of a straight pipe cylinder portion 36 and a pyramidal cylinder portion 35. The inner diameter of the straight pipe cylinder portion 36 and the pyramidal cylinder portion 3 are formed.
When the ratio of the inner diameter of the narrowest part of 5 to 20: 1 to 1: 1, preferably 10: 1 to 2: 1 is set, a good introduction speed can be obtained. These shapes and installation methods may be determined according to the properties of the powder raw material to be treated, and are not limited. The airflow classifier of the present invention as described above is effective in classifying powder raw materials for toner production, when the weight particle size of the powder raw materials is 10 μm or less,
Particularly, it is more effective when the thickness is 8 μm or less.

Further, the raw material supply pipe 16 is used together with the powder raw material for the air flow.
As a means for feeding into the air, a method of sending by applying a pressure of 0.1 to 3 kg / cm ² and an air blower on the downstream side of the classification zone are enlarged to increase the negative pressure in the classification zone to increase the outside air and powder. There is a method of naturally sucking the raw material, or a method of attaching an injection feeder to the powder raw material input port to suck the powder raw material and the outside air and sending it to the classification chamber 32 through the raw material supply pipe 16. . In the present invention, among the above-mentioned three powder raw material charging means, the method of increasing the negative pressure in the classification chamber 32 to naturally suck the outside air and the powder raw material, and the method using the injection feeder are This is preferable because it has a particularly favorable influence on the operating conditions.

The classification operation in the multi-division classification zone of the airflow type classification device having the above-mentioned structure is carried out, for example, as follows. First, the inside of the classifying chamber 32 is decompressed through at least one of the outlets 11, 12 and 13, and it is preferable that the air flow flowing in the raw material supply pipe 16 opening in the classifying chamber 32 caused by this depressurization causes Flow velocity 50-300m /
The powder material is classified at a rate of 2 seconds through the material supply pipe 16
Supply within 2. Next, the supplied powder raw material moves along the curved line 30 by the Coanda effect due to the action of the Coanda block 26 and the action of gas such as air flowing in at that time, and the particle diameter and the inertia of the particles are respectively generated. Depending on the magnitude of the force, large particles (coarse particles) are on the outside of the air flow, that is, on the first fraction on the left side of the classification edge 18, and particles of intermediate size (particles with a standard particle size) are on the classification edge 17. In the second fraction between No. 18 and 18, small particles (particles having a standard particle size or less) are respectively divided into the third fraction on the right side of the classification edge 17, and large particles have an intermediate size from the outlet 11. Particles are discharged from the outlet 12
The smaller and smaller particles are discharged from the discharge port 13, respectively.

In the classification of the powder raw material according to this example, the classification points are the tip positions of the classification edges 17 and 18 and the air intake edge 19 with respect to the left end portion of the Coanda block 26 where the powder jumps out into the classification chamber 32. It is mainly determined by the tip position. Further, the classification point is also affected by the flow rate of the classification air flow, the ejection speed of the powder raw material from the raw material supply pipe 16, and the like.

In the gas stream classifier of the present invention, when the powder raw material is introduced into the classifying chamber 32, a particle flow is formed by being dispersed according to the size of the particles in the powder. By changing the position of the classification edge 18 that separates the coarse powder group consisting of coarse particles and the medium powder group consisting of particles having the standard particle size along the line, it is possible to set a predetermined classification point. I can.
That is, by moving the classification edges 17 and 18 so that the orientations of the classification edges 17 and 18 are aligned with the flow direction of the particle group flying along the Coanda block 26,
It enables accurate classification.

FIG. 4 shows an enlarged view of the classification area of the airflow type classification apparatus of FIG. 1, which will be described below. For example, when a point O in the Coanda block 26 corresponding to the lower portion of the tip opening of the raw material supply pipe 16 is connected as a base point, and the point O is connected to the tip of each edge,
First, the distance a between the tip of the classification edge 17 and the wall surface of the Coanda block 26 can be adjusted by rotating the tip of the classification edge 17 around the shaft 17a. Similarly, the distance b between the tip of the classification edge 18 and the wall surface of the Coanda block 26 can be adjusted by rotating the tip of the classification edge 18 about the shaft 18a. Further, the distance c between the tip of the air intake edge 19 and the side surface of the Coanda block 26 can be adjusted by rotating the tip of the air intake edge 19 about the shaft 19a. As a result of these, by accurately changing the shape of the classification area of the classification chamber 32 and adjusting the classification point, accurate classification can be performed.

However, since the powder raw material moves at a high speed in the classifying device having the above-mentioned classification area, the surface which the powder raw material comes into contact with is instantaneously heated to a high temperature, causing a problem of toner fusion. . In particular, the wall surface of the raw material supply pipe 16 and the classification edge 17 on the trajectory of the toner particles flowing.
The problem is more remarkable in the wall surface portions of Nos. 18 and 18, and further in the wall surface portion of the intake edge 19.

Therefore, in order to solve the problem of toner fusion to these wall surfaces, the air flow classifying apparatus for toner production according to the present invention, in particular, the inner wall surface of the raw material supply pipe 16, the classification edges 17 and 18, and further includes The outer wall surface of the air edge 19 is made of a resin containing plastic-based polybenzimidazole as a main component to solve the above problem. That is, by configuring these members with a resin molded product containing plastic-based polybenzimidazole as a main component, or with a member whose surface is coated with a resin containing plastic-based polybenzimidazole as a main component, The problem is solved. That is, by adopting such a configuration,
Excellent sliding characteristics are obtained on the inner surface of the raw material supply pipe 16, the classification edges 17 and 18 and the surface of the air intake edge 19,
Sliding property of flowing particles is improved, and abrasion resistance can be satisfied. In particular, in the case of producing a powder raw material for toner, it is possible to suppress the generation of toner fusion products on the wall surfaces of these members, and it is possible to reduce the wear of the members constituting the apparatus.

In the present invention, a resin molded product containing a plastic polybenzimidazole resin as a main component may be used as the constituent members of the raw material supply pipe 16, the classification edges 17 and 18, and the air intake edge 19. Further, a member in which the surface of a metal material or the like is coated with a resin containing a plastic polybenzimidazole resin as a main component may be used. This may be appropriately selected depending on the situation of use.

As the resin containing the above-mentioned plastic-based polybenzimidazole resin as a main component, the resin may be used alone. For example, it depends on the material characteristics of the powder raw material for toner production to be used. Therefore, other materials may be appropriately blended with the plastic-based polybenzimidazole resin and used. The polybenzimidazole resin used in the present invention is a general term for heat-resistant polymers having a benzimidazole ring, and examples thereof include poly-p-phenylenebenzimidazole and polyalkylenebenzimidazole. Further, there are various methods for coating the above-mentioned member with a resin containing a plastic-based polybenzimidazole resin as a main component, for example, a method of dissolving the resin in an appropriate solvent and applying it on the surface of the member,
A publicly known method such as directly heat-melting and adhering a resin to the surface of a member or attaching a plastic resin-containing tape to a corresponding portion of the member may be used.

Further, in the present invention, the discharge ports 11, 1 are
By adjusting the flow rate of the suction flow due to the reduced pressure via 2 and 13, the flight speed of particles is increased to improve the dispersion of powder in the classification area, and good classification accuracy is obtained even at higher dust concentrations. Therefore, it is possible not only to prevent the product yield from decreasing but also to improve the product yield with better classification accuracy when the dust concentration is the same.

The airflow classifying apparatus of the present invention is not limited to the above-mentioned constitution, its shape and constituent materials, the apparatus system using the same, etc., and may be appropriately selected depending on the properties of the powder raw material to be treated. You can decide to. Further, the airflow classifying apparatus of the present invention has a weight particle size of 1 when the powder raw material for toner production is classified.
It is effective when it is 0 μm or less, and is more effective when the weight particle size of the powder raw material is 8 μm or less.

The airflow classifier according to the present invention is usually used as an integrated device system by connecting mutual devices by a communicating means such as a pipe. A preferred example of such an integrated device system is shown in FIG. The integrated device system shown in FIG. 3 is a three-division classifier 1 which is an example of the airflow classifier of the present invention.
(Shown in FIGS. 1 and 2; details have already been described). The constant quantity feeder 2, the vibration feeder 3, and the collecting cyclones 4, 5 and 6 are connected by an appropriate communicating means. is there.

In this integrated device system, first, the powder raw material is fed to the constant quantity feeder 2 by an appropriate means,
Then, the raw material supply pipe 16 is introduced into the three-division classifier 1 through the vibrating feeder 3. At this time, the powder raw material is introduced into the three-division classifier 1 at a flow rate of about 50 to 300 m / sec. The size of the classification chamber 32 of the three-division classification device 1 is usually [10 to 50 cm] × [10 to 50 cm].
The powder raw material is instantly divided into three or more kinds of particle groups for 0.1 seconds or less, or 0.01 seconds or less. For example, in the example shown in FIG. 3, the three-division classifier 1 converts the particles into large particles (coarse particles), intermediate particles (particles having a prescribed particle diameter), and small particles (particles having a prescribed particle diameter or less). Each is divided. After that, the large particles are discharged to the outside of the system through the discharge port 11 and recovered as coarse powder by the collecting cyclone 6. Particles of medium size are outlet 1
It is discharged to the outside of the system through 2 and is collected as much as a product (toner) by the collecting cyclone 5. The small particles are discharged out of the system through the discharge port 13 and are collected as fine powder by the collection cyclone 4. In the example described above, the collection cyclones 4, 5 and 6 function as suction decompression means for sucking and introducing the powder raw material into the classification chamber 32 via the raw material supply pipe 16.

The airflow classifier of the present invention is effectively used especially for classifying toner or colored resin powder used for image formation by electrophotography. In particular, it is effective when classifying a toner composition composed of a binder resin having a low melting point, a low softening point, or a low glass transition point. When a powder raw material for toner production using such a resin is classified by a conventional classifying device, a fused substance is easily generated at the tip of the classification edge, and the classification point is out of an appropriate range due to the generation of the fused substance. There is a tendency. In this case, even if the flow rate is adjusted by suction decompression, it is difficult to obtain the required particle size distribution of the powder, and the classification efficiency may be significantly reduced.
In addition, there is a problem that fused materials are mixed in the classified powder, and it becomes impossible to obtain high-quality products. With conventional classification equipment, stable operation for a long time is required to obtain products of constant quality. It was difficult to get me to do it.

On the other hand, by using the airflow classifier of the present invention, fusion at the tip of the classification edge and in the vicinity thereof is prevented or suppressed, so that the classification yield is improved and highly accurate classification is achieved. I can. Further, the airflow type classification device of the present invention,
Almost no fused substances or deposits are generated in the classifying device, so that it is possible to operate for a long time, and the classification process can be stably performed for a long time.

For example, when the powder raw material is classified by using the gas stream classifier of the present invention, the weight average particle diameter is particularly 10 μm.
A toner having a sharp particle size distribution can be obtained from the following powder raw materials for toner production, and classification can be performed more efficiently than in the past. In particular, if the airflow classifier of the present invention is used, a toner having a sharp particle size distribution can be obtained from a powder raw material for producing a toner having a weight average particle size of 8 μm or less. Therefore, a remarkable effect can be expected in the case of increasing the amount of the powder raw material to be crushed by the jet mill or in the case of obtaining a crushed product having a small particle size.

[0033]

EXAMPLES The present invention will be described in more detail with reference to Examples of the present invention. A specific example in which a product (toner) is actually obtained by using a powder raw material for toner production will be shown. Example 1 -Styrene-butyl acrylate-divinylbenzene copolymer (monomer polymerization weight ratio 80.0 / 19.0 / 1.0, weight average molecular weight = 350,000) 100 parts by weight-Magnetic iron oxide (average particle size 0 .18 μm) 100 parts by weight Nigrosine 2 parts by weight Low molecular weight ethylene-propylene copolymer 4 parts by weight A material of the above formulation was applied to a Henschel mixer (FM-75).
Type, well mixed by Mitsui Miike Chemical Industry Co., Ltd., and then kneaded by a twin-screw kneader (PCM-30 type, manufactured by Ikegai Iron Works Co., Ltd.) set at a temperature of 150 ° C. The obtained kneaded product was cooled, coarsely pulverized with a hammer mill to 1 mm or less, and a 1 mm screen passing product was finely pulverized with a jet mill of a collision type airflow pulverizer to obtain a powder raw material.

The toner raw material obtained as described above was classified as follows using the apparatus system shown in FIG.
First, the powder raw material obtained above is categorized into three types, that is, a coarse powder, a medium powder and a fine powder by utilizing the Coanda effect through the constant quantity feeder 2, the vibration feeder 3 and the raw material supply pipe 16. In order to carry out classification, it was introduced into the three-division classification device 1 shown in FIG. At the time of introduction, the suction force derived from the reduced pressure in the system by the suction of the collection cyclones 4, 5 and 6 communicating with the discharge ports 11, 12 and 13 and the ink injection feeder 31 attached to the raw material supply pipe 16 Of compressed air was used. In the present embodiment, an apparatus in which a plastic polybenzimidazole resin molded product was used for the members of the raw material supply pipe 16, the classification edges 17 and 18, and the air intake edge 19 was used.

After carrying out continuous operation for one month using the apparatus system having the above-mentioned constitution, the air flow type classifying apparatus is disassembled and the state of the raw material supply pipe 16, the classifying edges 17 and 18, and further the state of the intake edge 19 are changed. As a result of observation, neither wear of the member nor fusion phenomenon to the member was observed at all. The particle size of the classified product obtained during the continuous operation for one month was stable.

Comparative Example 1 Using the same powder raw material for toner production as in Example 1, FIG.
The classification was performed by the conventional integrated device system shown in. That is,
The powder raw material is supplied in a constant quantity by a feeder 102 and a vibration feeder 103.
Then, it was introduced through the raw material supply pipe 116, and was introduced into the three-division classification device 101 shown in FIG. 5 in order to classify into three types of coarse powder, medium powder and fine powder by utilizing the Coanda effect. At the time of introduction, as in the first embodiment, the discharge ports 111, 11
Collection cyclones 104, 1 communicating with 2 and 113
The suction force derived from the reduced pressure in the system by the suction of 05 and 106 and the compressed air from the ink injection feeder 131 attached to the raw material supply pipe 116 were used. In the comparative example, a fluororesin molded product was used as the material for the raw material supply pipe 116, the classification edges 117 and 118, and the air inlet edge 119.

In the same manner as in Example 1, in order to classify the raw material powder into three particle groups, continuous operation was carried out, and after 2 days, the particle size of the classified product became very coarse. Then, the airflow classifier 101 was disassembled, and the state of the inner surface of the raw material supply pipe 116, the classification edges 117 and 118, and the surface of the air intake edge 119 were observed, and the inner wall surface of the raw material supply pipe 116 and the air intake edge 119 were observed. Almost no fusion was observed at the tip portion, but the fusion material was stuck to the surfaces of the classification edges 117 and 118. Therefore, to continue driving, classification edge 1
Both members 17 and 118 had to be replaced.

Comparative Example 2 The same powder raw material for toner production as used in Example 1 was used to perform classification using a conventional integrated device system shown in FIG. In this embodiment, the raw material supply pipe 1 of the three-division classifier
16, classification edges 117 and 118, and intake edge 1
19 constituent members formed of SUS304 were used. When continuous operation was performed in the same manner as in Example 1, an abnormality was found in the particle size of the classified product obtained after 2 days. Therefore, the operation was stopped, the airflow classification device 101 was disassembled, and the raw material supply pipe 116, The states of the classification edges 117 and 118 and the air intake edge 119 were visually observed. As a result, on the surfaces of the classification edges 117 and 118, and further on the surface of the air inlet edge 119, a fused substance of the toner was stuck as a layer, and the inside of the raw material supply pipe 116 was considerably worn.
Therefore, it was impossible to continue driving any further.

[0039]

As described above, according to the airflow classifying apparatus for producing an electrostatic image toner of the present invention, a raw material supply pipe,
By appropriately selecting the materials of the classification edge and the air intake edge, the fusion of the toner component into the classification device is reduced, and the wear of the members in the device is prevented,
Accurate classification points can be obtained according to the specific gravity and classification airflow conditions of various powder raw materials, toners with a sharp particle size distribution can be obtained with high classification yield, and continuous stable toner product production can be achieved. Is possible. Furthermore, the raw material supply pipe in the classifier, no fusion material is generated on the classification edge and the air intake edge,
In addition, wear inside the device can be prevented. As a result, the frequency of replacement of these can be reduced, and the cost can be reduced according to the present invention. Further, the toner manufacturing apparatus system in which the airflow classifying apparatus of the present invention is used, the image density is stable and high as compared with the conventional apparatus, the durability is high, and there is no image defect such as fog or cleaning failure. An excellent electrostatic image developing toner having a particle size of

Particularly, according to the airflow type classification apparatus of the present invention,
It is possible to efficiently obtain a toner having a sharp particle size distribution from a powder raw material for producing a toner having a weight average particle diameter of 10 μm or less, and further, a weight average particle diameter of 8 μm.
A toner having a sharp particle size distribution can be efficiently obtained from the following powder raw materials for toner production.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an airflow classification device of the present invention.

2A and 2B are a side view and a perspective view of the airflow classification device of FIG.

FIG. 3 is a diagram showing an apparatus system using the airflow classifier shown in FIG.

FIG. 4 is an enlarged view of a classification area portion of the airflow classification device of FIG.

FIG. 5 is a cross-sectional view showing an example of a conventional airflow classifier.

6A and 6B are a side view and a perspective view of the airflow classification device of FIG.

7 is a diagram showing an apparatus system using the airflow type classification apparatus shown in FIG.

[Explanation of symbols]

1, 101: Air flow type three-division classifier 2: Fixed amount feeder 3: Vibratory feeder 4, 5, 6, 104, 105, 106: Collection cyclone 11, 12, 13, 111, 112, 113: Discharge port 14, 15, 114, 115: Inlet port 16, 116: Raw material supply pipe 16a: Opening of raw material supply pipe 17, 117: Classification edge for separating a medium powder group and a fine powder group 18, 118: Coarse powder Classifying edge 17a: axis of classifying edge 17 18a: axis of classifying edge 18, 19: 119: inlet edge 19a: axis of inlet edge 20, 120: first gas introduction control Means 21, 121: Second gas introduction adjusting means 22, 122: Air inlet side wall 23, 24, 123, 124: Side wall 25, 125: Lower wall 26, 126: Coanda block 27, 127: Upper wall 28, 9,128,129: static pressure meter 30: particles scattering trajectory (curved line) 31, 131: Injection feeder 32, 132: classifying chamber

Claims (1)

[Claims] 1. An airflow type classifying device for classifying a powder raw material for toner production by an airflow, comprising a classification area formed by at least a Coanda block, individual wall blocks and a plurality of classification edges, The powder raw material is jetted by an air flow flowing in a raw material supply pipe having an opening in the classifying device in the classification area, and the powder raw material in the jetted air flow is converted into a curved air flow due to the inertia force of the particles and the Coanda effect. At least one of a raw material supply pipe, a classification edge and an air intake edge is selected in accordance with the specific gravity of the powder raw material, the target classification point and the raw material supply speed in an air flow type classification device for classifying into a plurality of particle groups having different particle sizes by centrifugal force. Part is a resin molded product containing plastic-based polybenzimidazole as a main component, or the surface is coated with a resin containing plastic-based polybenzimidazole as a main component An airflow classifier characterized by being constituted by a bent member.