JP4076159B2 - Classification device and developer production method - Google Patents

Description

  In the present invention, a powder material is supplied together with carrier air from a powder material supply port, and the powder material is dispersed by a swirling flow formed by the carrier air, and continuously provided below the dispersion chamber. A classification chamber for applying a centrifugal force to the powder material flowing from the dispersion chamber, a conical member for separating the dispersion chamber and the classification chamber, and a powder to which a centrifugal force is applied below the conical member The present invention relates to a classification device having a classification plate for classifying materials into fine powder and coarse powder, and a method for producing a developer produced by the classification device.

  Conventionally, a classification apparatus for separating a micron-order powder material into coarse powder and fine powder is constituted by a cylindrical dispersion chamber and a classification chamber. A conical member is provided between the dispersion chamber and the classification chamber, and the powder material is supplied from the mouth of one end of the upper outer surface of the dispersion chamber, and receives a dispersing action by the swirling flow formed in the dispersion chamber. Further, it is guided to the classification chamber and is discharged to the fine powder outlet or the coarse powder outlet by centrifugal separation, so that the powder material is separated into coarse powder and fine powder.

  FIG. 9 is a cross-sectional view showing a configuration of a conventional classification device. The conventional classifier shown in FIG. 1 includes a supply pipe 11 to which inflow air as primary carrier air and a powder material are supplied, an exhaust pipe 12 from which ultrafine powder is discharged together with air, a dispersion chamber 13, An air inlet 14 that is secondary transport air fed into the dispersion chamber 13, a fine powder discharge port 15 that discharges fine powder together with air, a coarse powder discharge port 16 that discharges coarse powder together with air, and a lower portion of the dispersion chamber 13 The conical member 17 for increasing the swirling flow field in the dispersion chamber 13, the classification plate 18 provided at the lower portion thereof, and the dispersion chamber 13 are partitioned by the conical member 17 and the classification plate 18. And a classifying chamber 19. In addition, the whole classification apparatus main body consists of a substantially cylindrical housing | casing.

Next, the operation of this classifier will be described.
First, air is supplied from the supply pipe 11 and the air inflow port 14, and at the same time, air is discharged from the exhaust pipe 12, the fine powder discharge port 15 and the coarse powder discharge port 16, whereby each inside of the dispersion chamber 13 and the classification chamber 19. A swirl flow field is formed in the. The powder material is supplied together with air from the supply pipe 11 and guided into the dispersion chamber 13, and the powder material falls while rotating while receiving the centrifugal separation action by the swirling flow field of air.

  At this time, the ultrafine powder having a very small particle size is guided to the center of the dispersion chamber 13 and is discharged from the exhaust pipe 12 communicating with a suction device (not shown) such as a suction fan. Become. The powder material that has fallen while rotating in the dispersion chamber 13 passes through the annular gap A and is guided to the classification chamber 19, and here, too, by being subjected to a centrifugal separation action, large coarse powder among the powder material is subjected to centrifugal force. From the center of the classification chamber 19, passing through an annular gap B between the classification plate 18 and each inner wall surface of the classification chamber 19, and from a coarse powder outlet 16 communicating with a suction device (not shown) such as a suction fan. Discharged. On the other hand, the fine powder is guided to the center of the classification chamber 19 by centripetal force and discharged from the fine powder discharge port 15 communicating with a suction device (not shown) such as a suction fan.

In the conventional classification device having such a configuration, there is a problem that the variation in the particle size of the classified powder becomes large. On the other hand, the apparatus which comprises the fine powder suction tube of the classification chamber center part in a classification apparatus with a multiple tube is disclosed (for example, patent document 1). According to this, a large powder material having a desired particle diameter or larger is not sucked by the fine powder suction tube constituted by multiple tubes, and is guided to the lower part of the apparatus main body, while a powder material having a desired particle diameter or smaller is guided by this. The powder is sucked into a fine powder suction tube made up of multiple tubes, and in a powder material having a desired particle size or less, the powder material having a large particle size is sucked into an outer suction tube made up of multiple tubes and collected. On the other hand, solid particles with a small particle size are sucked and collected by an inner suction tube consisting of multiple tubes, and powder materials with different particle sizes are individually sucked through the respective suction tubes composed of multiple tubes. And recovered.
JP 2000-107698 A

  However, by making the powder suction tube into multiple tubes, there is a possibility that powder materials having different particle diameters will be individually sucked and collected through each suction tube, but were recovered to the desired particle size or more. Since the amount of the powder material having a particle size equal to or smaller than the desired particle size contained in the powder material, that is, the amount of fine powder does not change greatly, the variation in the particle size of the collected powder material does not become small.

  Further, by providing a guide plate in the classification chamber, even if a powder material having a particle size larger than the powder material having a particle size corresponding to each suction tube constituted by multiple tubes is introduced, the desired particle size can be obtained. Larger powder is guided downward along the guide plate, and powder material larger than the desired particle size can be prevented from being sucked and collected by each suction tube. If a certain guide plate is provided, the speed toward the fine powder suction tube along the guide plate wall surface increases, and therefore, there is a possibility that large particles having a particle size larger than the desired particle size may be collected into the fine powder suction tube. Therefore, there is a problem that the variation in the particle size of the recovered powder material does not become small.

  Therefore, the problem of such a classification device is to improve classification accuracy in the classification chamber. Solid particles are guided from the dispersion chamber to the classification chamber. The ideal classification is that all powder materials with a desired particle size or more are on the coarse powder collection side, and powder materials with a desired particle size or less are on the fine powder collection side. To be recovered. However, in an actual classification device, there is a classification error that a powder material having a desired particle size or more is collected to the fine powder collection side and a powder material having a desired particle size or less is collected to the coarse powder collection side. There's a problem.

  In addition, as shown by the arrows in FIG. 10, a flow having a distribution is formed inside the classification chamber 19 of the classifier, and the speed is particularly high near the center of the lower surface 17b of the conical member 17 as compared with the others. Therefore, the powder material introduced into the classification chamber 19 is easily guided to the central part of the classification device without being classified, and there is a problem that the classification accuracy is lowered.

Therefore, there is a need for a classification device that can obtain a sharp distribution with little classification error.
In order to solve these problems, the present invention achieves an improvement in classification accuracy in the classification chamber of the classification device, separates particles in a required size range with high efficiency, and improves the classification accuracy. The purpose is to provide.

The invention according to claim 1 is a dispersion chamber for supplying powder material together with carrier air from a powder material supply port, and dispersing the powder material in a swirl flow formed by the carrier air;
An exhaust pipe for exhausting a part of the carrier air;
A classification chamber that is provided continuously below the dispersion chamber and that imparts centrifugal force to the powder material flowing from the dispersion chamber;
A conical member separating the classification chamber and the dispersion chamber;
A classification plate disposed at a lower portion of the classification chamber and classifying the powder material to which centrifugal force is applied;
The powder material is swirled and dispersed by the swirl flow formed in the dispersion chamber to discharge ultra fine powder from the exhaust pipe, and the powder material is classified into fine powder and coarse powder by the classification plate. In the classification device,
A fine powder collection promoting means for promoting fine powder collection is provided on the upper surface side of the classification plate.

According to the first aspect of the present invention, since the fine powder collection promoting means for promoting the fine powder collection is provided on the upper surface side of the classification plate, the velocity distribution in the classification chamber is changed, and the unclassified powder material is mixed with the fine powder. This makes it possible to collect fine powder of the powder material with high accuracy.
Therefore, it is possible to improve the classification accuracy in the classification chamber of the classification device, separate particles in a required size range with high efficiency, and provide a classification device with improved classification accuracy.

Further, in the classification device according to the first aspect of the present invention, in the classification device, the fine powder collection promoting means is a disk having a predetermined thickness with a cavity in the center, and the outer periphery of the upper surface of the disk is the outer periphery of the lower surface. It is characterized by being smaller.

According to the invention of claim 1 , the fine powder recovery promoting means is a disk having a predetermined thickness having a cavity in the center, and the outer periphery of the upper surface of the disk is smaller than the outer periphery of the lower surface. By changing the velocity distribution in the classification chamber, it is possible to accurately collect the fine powder of the powder material.

Moreover, the classification apparatus of Claim 1 WHEREIN: The thickness and the magnitude | size of the said disk can be changed according to the classification conditions of the said powder material .

According to the above, the thickness and size of the disk, so was that varied according to the classification condition of the powder material, can flexibly correspond to the classification conditions, to improve the recovery of the desired powder material It becomes possible.

According to a second aspect of the invention, the classification device according to claim 1, wherein the providing a plurality of the fine particle collection promoting means.

According to the second aspect of the present invention, since a plurality of fine powder collection promoting means are provided, the velocity distribution inside the classification chamber is further changed, further preventing the unclassified powder material from being mixed with the fine powder, and collecting the fine powder with high accuracy. It can be done well. In particular, providing a plurality of fine powder collecting members is effective when the height of the classification chamber is higher.

The invention according to claim 3 is characterized in that, in the classification device according to claim 1 or 2 , the fine powder collection promoting means is detachable from the classification plate.

According to the invention of claim 3 , since the fine powder collection promoting means is detachable from the classification plate, it can easily cope with a change in conditions such as the processing amount of the powder material, the average particle diameter, etc., and the switching time is shortened. Can also be achieved.

According to a fourth aspect of the present invention, in the classifying device according to any one of the first to third aspects, a circle having a predetermined thickness and diameter is formed on the lower surface of the conical member provided above the fine powder recovery promoting means. An annular ring-shaped member is provided.

According to the fourth aspect of the present invention, since the annular ring-shaped member having a predetermined thickness and diameter is provided on the lower surface of the conical member, the flow in the lower part of the conical member is changed, and the center of the conical member is changed. Therefore, the flow rate to the other place becomes faster and the powder material is easily guided to the center of the classification chamber, thereby reducing the deterioration of classification.

According to a fifth aspect of the present invention, in the classification device according to the fourth aspect , a plurality of the ring-shaped members are provided.

According to the invention of claim 5 , since a plurality of ring-shaped members are provided, the deterioration of the classification property is further reduced.

Moreover, the classification apparatus of Claim 4 or 5 WHEREIN: The thickness and diameter of the said ring-shaped member are good also as what was changed according to the classification conditions of the said powder material .

According to this, by the thickness and diameter of the ring-shaped member is varied in accordance with the classification condition of the powder material, can flexibly correspond to the classification conditions, possible to improve the recovery of the desired powder material Become.

A sixth aspect of the present invention is the classification apparatus according to the fourth or fifth aspect , wherein the ring-shaped member is detachable from the conical member.

According to the invention of claim 6 , since the ring-shaped member is detachable from the conical member, it is possible to easily cope with a change in conditions such as adjustment of the height and thickness of the ring-shaped member and a change in classification. Thus, the switching time can be shortened.

A seventh aspect of the present invention is the classifying device according to any one of the fourth to sixth aspects, wherein an upper portion of the ring-shaped member has a curved surface shape.

According to the seventh aspect of the present invention, since the upper part of the ring-shaped member has a curved surface shape, it is possible to prevent the powder material from adhering to the upper part of the ring-shaped member.

According to an eighth aspect of the present invention, in the developer manufacturing method for visualizing a latent image used in an electrophotographic image forming apparatus, the powder material is pulverized, and then any one of the first to seventh aspects. The developer is classified by the classifying apparatus described in 1.

According to the eighth aspect of the present invention, the developer can be produced by the classifying apparatus having the characteristics of any one of the first to seventh aspects.

According to the first aspect of the present invention, since the fine powder collection promoting means for promoting the fine powder collection is provided on the upper surface side of the classification plate, the velocity distribution in the classification chamber is changed, and the unclassified powder material is mixed with the fine powder. This can be prevented and fine powder of the powder material can be collected with high accuracy.
Therefore, it is possible to improve the classification accuracy in the classification chamber of the classification device, to separate particles in a required size range with high efficiency, and to provide a classification device with improved classification accuracy.

Further , according to the invention of claim 1 , the fine powder recovery promoting means is a disk having a predetermined thickness having a cavity in the center, and the outer periphery of the upper surface of the disk is smaller than the outer periphery of the lower surface. By changing the velocity distribution in the classification chamber with a simple structure, fine powder of powder material can be collected with high accuracy.

Further, by changing the thickness and size of the disk according to the classification conditions of the powder material, it is possible to flexibly cope with the classification conditions and improve the recovery rate of the desired powder material.

According to the second aspect of the present invention, since a plurality of fine powder collection promoting means are provided, the velocity distribution in the classification chamber is further changed, and the unclassified powder material is further prevented from being mixed with the fine powder. Recovery can be performed with higher accuracy. In particular, providing a plurality of fine powder collecting members can be effective when the height of the classification chamber is higher.

According to the third aspect of the present invention, since the fine powder recovery promoting means is detachable from the classification plate, it can easily cope with a change in conditions such as the processing amount of the powder material, the average particle diameter, and the switching time. Can be shortened.

According to the invention described in claim 4, since the annular ring-shaped member having a predetermined thickness and diameter is provided on the lower surface of the conical member provided above the fine powder recovery promoting means , By changing the flow in the lower part, the flow to the center of the conical member is faster than other places, and the powder material is easily guided to the center of the classification chamber, so that the deterioration of the classification property can be reduced.

According to the invention described in claim 5 , since a plurality of ring-shaped members are provided, the deterioration of classification can be further reduced.

Also, the thickness and diameter of the ring-shaped member by varied depending on the classification condition of the powder material, can flexibly correspond to the classification conditions, it is possible to improve the recovery of the desired powder material.

According to invention of Claim 6 , since a ring-shaped member is detachable from the said cone-shaped member, it is easy with respect to condition changes, such as adjustment of the height and thickness of a ring-shaped member, and a change of classification property. It is possible to cope with this, and the switching time can be shortened.

According to the seventh aspect of the invention, since the upper part of the ring-shaped member has a curved surface shape, it is possible to prevent the powder material from adhering to the upper part of the ring-shaped member.

According to the eighth aspect of the present invention, the developer can be produced by the classifying apparatus having the feature according to any one of the first to seventh aspects.

  In the classifying device of the present invention, the powder material supplied from the powder material supply port provided in the upper part of the dispersion chamber is subjected to a swirling and dispersing action by a swirling flow formed in the dispersion chamber, and discharges ultrafine powder. Further, the powder material is guided to a classification chamber and classified into coarse powder and fine powder by centrifugation. And the fine powder collection | recovery acceleration | stimulation means provided in the classification chamber changes the velocity distribution in a classification chamber, and collect | recovers fine powder of a powder material accurately.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration of a classification device according to an embodiment of the present invention.
In this example, the classifying device having a substantially cylindrical casing includes a supply pipe (powder material supply port) 1 for supplying powder material together with carrier air, and a swirl flow formed by the carrier air. Dispersion chamber 3 that disperses body material, exhaust pipe 2 that exhausts a part of the carrier air, and a continuous lower portion of the dispersion chamber 3, and imparts centrifugal force to the powder material flowing from the dispersion chamber 3 A classifying chamber 9, a conical member 7 separating the classifying chamber 9 and the dispersion chamber 3, a classifying plate 8 disposed under the classifying chamber 9 and classifying the powder material to which centrifugal force is applied, An air inlet 4 for feeding the secondary carrier air into the dispersion chamber 3, a fine powder outlet 5 for discharging fine powder, and a coarse powder outlet 6 for discharging coarse powder are provided below.

  Furthermore, fine powder collection promoting means 11 for promoting the collection of fine powder is provided on the upper surface 8 a side of the classification plate 8. As shown in detail in FIG. 2, the fine powder collection promoting means 11 is a disk having a predetermined thickness having a cylindrical cavity in the center portion 11c, and the outer periphery 11a on the upper surface of the disk is the outer periphery 11b on the lower surface. It has a smaller structure. The thickness and size of this disk are changed according to the classification conditions of the powder material. Moreover, the cavity of the center part 11c is not limited to a cylindrical shape.

  And the fine powder collection | recovery promotion means 11 may fix the fine powder collection | recovery promotion means 11 to the classification board 8 using the volt | bolt 13 and connection member AT, as shown in FIG. If it does in this way, it will become removable from the classification board 8, the fine powder collection | recovery acceleration | stimulation means 11 can be easily provided in the upper part of the classification board 8, and it is easy to change conditions, such as the processing amount of a powder material, an average particle diameter, etc. It is possible to cope with it and shorten the switching time.

  Therefore, the fine powder content in the powder material recovered from the coarse powder outlet 6 is reduced, and a sharp distribution with little classification error is obtained. Note that the fine powder collection promoting means 11 is preferably formed of SUS or SS.

  The classifier configured in this way supplies the powder material together with the carrier air from the supply pipe 1, and disperses the powder material by the swirling and dispersing action in the dispersion chamber 3 by the swirling flow formed by the carrier air. Then, the super fine powder is discharged from the exhaust pipe 2 together with a part of the carrier air. The powder material supplied to the dispersion chamber 3 descends while swirling the dispersion chamber 3 and is guided to the classification chamber 9. The powder material is promoted by the fine powder collection promoting means 11 provided on the classification plate 8 inside the classification chamber 9. Collect fine powder and coarse powder of body materials with high accuracy. That is, by providing the fine powder collection promoting means 11, the velocity distribution in the classification chamber 9 is changed, a flow guided to the fine powder discharge pipe 5 is generated, and the fine powder is accurately collected to the fine powder discharge port 5.

As shown in FIG. 4, the fine powder collection promoting means 11 </ b> A and 11 </ b> B may be divided into two stages (plural) on the upper surface of the classification plate 8 and provided at a constant interval. In this case, a mounting portion (not shown) may be provided in the middle stage of the connecting member AT shown in FIG. 3 and the fine powder collection promoting means 11A, 11B may be attached to the connecting member AT with the bolts 13.
In this way, the fine powder can be collected to the fine powder discharge port 5 with higher accuracy.

  Furthermore, as shown in FIG. 5, by providing an annular ring-shaped member 12 having a predetermined thickness d and diameter b on the lower surface 7b of the conical member 7 provided at the upper part of the classification chamber 9, the lower surface 7b By changing the flow along, it is possible to prevent the powder material to be collected to the coarse powder collection side from being guided to the fine powder collection side, and improve the classification accuracy. The ring-shaped member 12 is not particularly limited to a perfect circular ring.

  In addition, the diameter b of the ring-shaped member 12 is equal to or larger than the diameter c of the lower convex portion of the conical member 7. This is because the flow along the wall surface does not change greatly even if it is set to the diameter c or less of the lower convex part of the conical member 7, and as a result, the movement of the powder material hardly changes. This is because the powder material having a particle size to be guided to the coarse powder collection side cannot obtain an effect that prevents the action to be guided to the fine powder collection side.

In addition, the thickness d of the ring-shaped member 12 is 30% or less of the lower radius a of the conical member 7. This is because if the thickness of the ring-shaped member 12 is too thick, the flow in the classification chamber changes greatly, causing problems such as a reduction in the recovery rate of the powder material. The thickness d and the diameter b of the ring-shaped member 12 is varied according to the classification conditions of the powder material.

  In addition, as shown in FIG. 6, by providing two ring-shaped members 121 and 122 on the lower surface 7b of the conical member 7 provided in the upper part of the classification chamber 9, the flow along the wall surface further changes, and the coarse powder The action of the powder material having a particle size to be guided to the collection side can be further prevented from being guided to the fine powder collection side. The ring-shaped members 121 and 122 are not limited to two, and two or more ring-shaped members 121 and 122 may be provided. By doing so, the flow along the wall surface can be further changed, and the action of the powder material being guided to the fine powder collection side can be further prevented.

  In addition, as shown in FIG. 7, the height h of the ring-shaped member 12 is set to ½ or less of the height H of the classification chamber 9 (see FIG. 1). If the height h of the ring-shaped member 12 is too high, the flow inside the classification chamber 9 will change greatly, causing problems such as a reduction in the recovery rate of the powder material. The height h of the ring-shaped member 12 can be varied according to the classification conditions.

  And the outer surface 12A and the inner surface 12B of the upper part 12c of the ring-shaped member 12 were made into the curved surface shape. As a result, the flow tends to stagnate in the portion where the ring-shaped member 12 is provided on the lower surface 7b of the conical member 7, and in continuous operation, the powder material is likely to accumulate, the recovery rate decreases, and the cleaning property It is possible to prevent problems such as deterioration. Note that the above-described effects can be obtained even if the curved surface shape is applied to either the outer surface 12A or the inner surface 12B.

  Furthermore, as shown in FIG. 8, the ring-shaped member 12 may be detachable from the conical member 7. A groove 7a for attaching the ring-shaped member 12 is formed on the back surface 7b of the conical member 7, and the ring-shaped member 12 formed by bending the tip 12t into an L-shape in the groove 7a is, for example, a detaching mechanism such as a screw 14. Tighten with and attach. Accordingly, it becomes easy to provide the ring-shaped member 12 on the lower surface 7b of the conical member 7 provided at the upper part of the classification chamber 9, and the height can be easily adjusted by exchanging with the ring-shaped member 12 having a different height. Yes. In addition, since the ring-shaped member 12 can be detached, the switching operation of the ring-shaped member 12 can be shortened.

  Next, regarding a method for producing a developer that visualizes a latent image used in an electrophotographic image forming apparatus, the powder material is pulverized and then classified by a classifier shown in FIG. 1 to produce the developer. How to do will be described.

  A mixture of 85 parts by weight of a styrene-acrylic copolymer resin and 15 parts by weight of carbon black is melt-kneaded and cooled, coarsely pulverized with a hammer mill, and then finely pulverized with a jet mill. Examples 1 to 8 classified by the classifying apparatus shown in FIG.

Example 1
As shown in FIG. 1, in a classification device in which fine powder collection promoting means 11 is installed on the upper part of the classification plate 8, the powder material having the above composition is supplied and set to an exhaust blower pressure of 1620 mmAq. When the diameter was set to φ63 mm, outer diameter φ96 mm, height 35 mm, and volume average particle size 7.5 μm (measured with a Coulter Counter), the volume average for a feed rate of 10.5 kg / h Particle size of 7.31 μm, fine powder content of 4 μm or less (wt%) 6.59, coarse powder content of 12.7 μm or more (wt%) 2.05%, sharp particle size compared to the comparative example shown below A distribution was obtained.

(Example 2)
Two fine powder collection promoting means 11 were installed in the classification chamber 9, the height was set to 23 mm, and the others were processed under the same conditions as in Example 1. As a result, for a feed rate of 10.5 kg / h, a volume average particle size of 7.44 μm, a fine powder content of 4 μm or less (wt%) 5.17, a coarse powder content of 12.7 μm or more (wt%) 2 A sharp particle size distribution was obtained with respect to the comparative example.

(Example 3)
In a classification apparatus in which a ring-shaped member 12 is provided at the lower part of a conical member 7 provided at the upper part of the classification chamber 9, a powder material having the above composition is supplied, an exhaust blower pressure of 1620 mmAq, a height h of the ring-shaped member 12 is provided. Was set to about 1/20 of the height H of the classifying chamber 9, the thickness d of the ring-shaped member 12 was set to 1.5 mm, and the diameter b was set to 170 mm. When classification was performed so that the volume average particle size was 7.5 μm (measured with a Coulter counter), the content of fine powder having a volume average particle size of 7.52 μm and 4 μm or less (weight) with respect to a feed amount of 10.5 kg / h. %) 4.47, 12.7 μm or more of coarse powder content (% by weight) was 2.51%, and a sharp particle size distribution was obtained with respect to the comparative example.

Example 4
A powder material having the same composition as in Example 1 was supplied, and two ring-shaped members 12 having a diameter b of 170 mm and 150 mm were provided, and the others were processed under the same conditions as in Example 1. As a result, for a feed rate of 10.5 kg / h, a volume average particle size of 7.63 μm, a fine powder content of 4 μm or less (wt%) 4.05, a coarse powder content of 12.7 μm or more (wt%) 2 A sharp particle size distribution was obtained with respect to the comparative example.

(Example 5)
A powder material having the same composition as in Example 1 was supplied, and the upper outer side of the ring-shaped member 12 was formed into a curved surface shape, and the others were processed under the same conditions as in Example 1. As a result, the accumulation of the powder material at the conical member lower mounting portion is reduced, and the cleaning property is improved.

(Example 6)
A powder material having the same composition as in Example 1 was supplied, and the upper inner side of the ring-shaped member 12 was formed into a curved shape, and the others were processed under the same conditions as in Example 1. As a result, the accumulation of the powder material at the conical member lower mounting portion is reduced, and the cleaning property is improved.

(Example 7)
A powder material having the same composition as in Example 1 was supplied to make it possible to detach the fine powder recovery promoting means 11, and the others were processed under the same conditions as in Example 1 and then cleaning switching was performed. As a result, the cleaning switching time can be reduced by about 10% compared to the specific example 1.

(Example 8)
A powder material having the same composition as in Example 1 was supplied so that the ring-shaped member 12 could be removed, and the others were processed under the same conditions as in Example 1, and then cleaning switching was performed. As a result, the cleaning switching time can be reduced by about 15% compared to the specific example 1.

(Comparative example)
The powder material having the above composition is supplied, and classification is performed using the conventional classifier shown in FIG. 8 so that the volume average particle size is 7.5 μm (measured by a Coulter counter) under the condition of an exhaust blower pressure of 1620 mmAq. Was processed. As a result, for a feed rate of 10.5 kg / h, a volume average particle size of 7.15 μm, a fine powder content of 4 μm or less (wt%) 10.87, a coarse powder content of 12.7 μm or more (wt%) 1 30%.

  In addition, this invention is not limited to the said Example, It cannot be overemphasized that various deformation | transformation and substitution are possible if it is description in a claim.

It is sectional drawing which shows the structure of the classification apparatus based on one Example of this invention. It is upper surface sectional drawing of a fine powder collection | recovery acceleration | stimulation means. It is sectional drawing which shows the structure of the classification apparatus based on another Example of this invention. It is a fragmentary perspective view which shows the example which attaches a fine powder collection | recovery acceleration | stimulation means to a classification board. It is sectional drawing which shows the example which attached the ring member to the conical member. It is sectional drawing which shows the example which attached two ring members to the conical member. It is principal part sectional drawing which shows the example which attached the upper part of the ring-shaped member to the cone-shaped member as the curved surface shape. It is principal part sectional drawing which shows the example which attached the ring-shaped member to the cone-shaped member so that attachment or detachment was possible. It is a schematic sectional drawing of the conventional classification apparatus. It is a figure for demonstrating the flow of the lower surface vicinity of the conical member with which FIG. 9 is equipped.

Explanation of symbols

1 Supply pipe (powder material supply port)
2 exhaust pipe 3 dispersion chamber 4 air inlet 5 fine powder outlet 6 coarse powder outlet 7 conical member 7a groove 7b back surface 8 classification plate 8a upper surface 9 classification chamber 11, 11A, 11B 11b outer periphery of the lower surface of the disk 11c center part of the disk 12, 121, 122 ring-shaped member 12A outer surface 12B inner surface 12c upper part 12t tip 14 screw AT connecting member

Claims (8)

A dispersion chamber for supplying powder material together with carrier air from a powder material supply port, and dispersing the powder material in a swirling flow formed by the carrier air;
An exhaust pipe for exhausting a part of the carrier air;
A classification chamber that is provided continuously below the dispersion chamber and that imparts centrifugal force to the powder material flowing from the dispersion chamber;
A conical member separating the classification chamber and the dispersion chamber;
A classification plate disposed at a lower portion of the classification chamber and classifying the powder material to which centrifugal force is applied;
The powder material is swirled and dispersed by the swirl flow formed in the dispersion chamber to discharge ultra fine powder from the exhaust pipe, and the powder material is classified into fine powder and coarse powder by the classification plate. In the classification device,
Having fine powder collection promoting means for promoting the collection of fine powder on the upper surface side of the classification plate;
The fine powder recovery promoting means is a disc having a predetermined thickness with a cavity in the center, and the outer periphery of the upper surface of the disc is smaller than the outer periphery of the lower surface.   The classification apparatus according to claim 1, wherein a plurality of the fine powder collection promoting means are provided.   The classification apparatus according to claim 1 or 2, wherein the fine powder collection promoting means is detachable from the classification plate. 4. The annular ring-shaped member having a predetermined thickness and diameter is provided on the lower surface of the conical member provided above the fine powder collection promoting means. 5. The classifier described.    The classification device according to claim 4, wherein a plurality of the ring-shaped members are provided.   The classification device according to claim 4 or 5, wherein the ring-shaped member is detachable from the conical member.   The classification device according to any one of claims 4 to 6, wherein an upper portion of the ring-shaped member has a curved shape. In a method for producing a developer that visualizes a latent image used in an electrophotographic image forming apparatus,
A method for producing a developer, comprising: pulverizing a powder material and then classifying the powder material with a classifier according to any one of claims 1 to 7 to produce the developer.

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