JP2007007523A - Classifying apparatus and classifying system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a classifying apparatus and a classifying system wherein inertial force is used for the classification having a highly accurate classifying effect, and a classifying apparatus and a classifying system that can achieve a high yield and a cost reduction by virtue of the highly accurate classifying effect. <P>SOLUTION: The classifying apparatus is equipped with a raw material powder supply pipe from which a solid-gas mixed flow comprising a gas flow and a raw material powder is ejected, an arc-shaped Coanda section disposed so that its tip is placed in the vicinity of the tip of the raw material supply pipe, a classifying edge for classifying the raw material powder, a gas introduction path for introducing a gas flow into a classifying chamber, and a discharge path for discharging the classified powder to the outside of the classifying chamber. The tip of the Coanda section is comprised of a cylindrical classifying rotor having an inner space and the classifying rotor has a plurality of slits on its entire circumference that pass through its circumferential wall toward its inner space. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a classification device and a classification system, and more particularly to a classification device and a classification system used in manufacturing toner used in an electrophotographic development system.

  The toner or colored resin powder used for image formation by electrophotography is currently mainly melt-kneaded a mixture containing at least a binder resin and a colorant, and the melt-kneaded product is cooled to be a cooled product. It is manufactured by pulverizing the obtained cooling product and further classifying the pulverized product.

  On the other hand, various airflow classifiers and airflow classification methods have been proposed for classifying the pulverized product. Among them, there are a classifier using a rotating blade and a classifier having no moving part.

  Among these, there are a fixed-wall centrifugal classifier and an inertial force classifier as classifiers having no moving parts.

As an inertial force classifier, one having a classifier shown in FIG. 5 has been conventionally used (for example, Patent Document 1).
Specific examples include elbow jet classifiers manufactured by Nippon Steel Mining.

  A conventional inertial force classifying classifier will be described with reference to FIG.

  FIG. 5 is a side sectional view of a conventional inertial force classifier.

  101a is a classification chamber, 111 to 115 are walls, 116 and 117 are inlet paths for introducing an air flow into the classification chamber 101a, and 118 to 120 are for discharging the classified powder out of the classification chamber 101a. , 112t is an inlet edge, 114t and 115t are classification edges for classifying the powder raw material, 121 is an arc-shaped Coanda block provided so as to protrude into the classification chamber 101a, and 130 is a powder A powder raw material supply unit including a raw material supply pipe 131 and a hopper 132, 131 is a powder raw material supply pipe for ejecting a solid-gas mixed flow composed of an air flow and a powder raw material, and 132 is for introducing the powder raw material. The hopper 170 a is a classification device including a classification chamber 101 a and a powder raw material supply unit 130.

  The classification chamber 101a includes walls 111 to 115, an inlet edge 112t, classification edges 114t and 115t, and a Coanda block 121.

  The interval between the wall 111 and the wall 112 is an inlet passage 116, the interval between the wall 112 and the wall 113 is an inlet passage 117, the interval between the wall 113 and the wall 114 is an outlet passage 118, and the walls 114 and 115 are The distance between the wall 115 and the Coanda block 121 is used as the discharge path 119.

  A powder raw material supply pipe 131 is inserted between the Coanda block 121 and the wall 111. At this time, the powder raw material supply pipe 131 is arranged so that the tips of the Coanda block 121, the classification edge 114t, and the classification edge 115t are located in the vicinity of the tip.

  The inlet edge 112 t is provided on the wall 112, the classification edge 114 t is provided on the wall 114, and the classification edge 115 t is provided on the wall 115.

  With the above configuration, the powder raw material particles are formed by the arc-shaped Coanda block 121 in which the airflows from the inlet passages 116 and 117 and the solid-gas mixed flow from the powder raw material supply unit 130 merge to turn the solid-gas mixed flow. The centrifugal force of the curved airflow due to the inertia force based on the size of the particle and the Coanda effect is applied, and the powder raw material is divided by the classification edges 114t and 115t into three types of coarse powder group G, medium powder group M, and fine powder group F Classification and discharge to discharge paths 118, 119, 120.

  Next, a conventional classification system will be described with reference to FIG.

  FIG. 6 is a diagram showing a conventional classification system.

  Reference numeral 102 denotes an ejection nozzle for ejecting an air flow into the inlet passages 116 and 117; 200a, classifiers; 300G, 300M, and 300F, three collection cyclones for introducing powder classified by the classifier 200a, respectively. , 400 is a common bag filter for collecting very fine ultrafine powder from the powder in the collection cyclones 300G, 300M, and 300F.

  The classifier 200a includes a jet nozzle 102 and a classifier 170a.

  The powder classified in the classification chamber 101a is classified into the coarse powder group G, the medium powder group M, and the fine powder group F along the arrows shown in FIG. 5, and the coarse powder group G is collected as shown in FIG. The cyclone 300G and the medium powder group M are introduced into the collection cyclone 300M, and the fine powder group F is introduced into the collection cyclone 300F.

  In the collection cyclones 300G, 300M, and 300F, the ultrafine powder is removed by suction from the common bag filter 400, the coarse powder G ′ remaining at 300G, the medium powder M ′ remaining at 300M, and the fine powder F remaining at 300F. 'Get each. The coarse powder G ′ is retransmitted to a pulverizer (not shown), the medium powder M ′ is recovered as a powder having a desired particle size, and the fine powder F ′ is reused for melt kneading.

JP 2002-1225 A

  However, the conventional classification device and classification system have the following problems.

  That is, the conventional classification device and classification system classify only by the Coanda effect, so the classification accuracy between the fine powder and the desired particle size is low, and the accuracy is reduced due to the adhesion of the fine powder to the Coanda block. The problem is that fine powder is mixed into powder of a desired particle size.

  For example, when the toner is classified using a conventional general inertial force classifier, if the Dv50 (volume 50% diameter measured by Coulter Multisizer II) of the desired toner is 5 to 7 μm, Since the powder in the fine powder region of 4.0 μm or less is mixed in 15.0 to 18.0% by number, the amount of powder mixed in the fine powder region of 4.0 μm or less, which is necessary for practical use, is achieved in 12.0% by number or less. That was difficult.

  In addition, a phenomenon in which powder having a desired particle size to be collected as a product enters the fine powder group F also occurred, causing a decrease in yield and high cost.

  The present invention has been made in order to solve such a problem, and an object thereof is a classification device using inertial force, and a classification device and a classification capable of obtaining a highly accurate classification effect. To provide a system.

  Another object of the present invention is to provide a classification device and a classification system capable of realizing a yield increase and cost reduction by a highly accurate classification effect.

The present invention has achieved the above-mentioned object by the following technical configuration.
(1) A powder raw material supply pipe for ejecting a solid-gas mixed flow composed of an air flow and a powder raw material, an arc-shaped Coanda portion arranged so that the tip comes near the tip of the powder raw material supply pipe, A classification device comprising a classification edge for classifying powder raw materials, an inlet path for introducing an air flow into a classification chamber, and a discharge path for discharging the classified powder out of the classification chamber. The classification device is characterized in that the tip of the Coanda portion is a cylindrical classification rotor having an internal space, and the classification rotor has slits penetrating toward the internal space in the entire outer peripheral surface.
(2) The classification device according to (1), which is used for classification of toner for electrophotography.
(3) The coarse powder group G, the medium powder group M, and the fine powder group F classified by the classification device according to (1) are discharged from the discharge paths 118, 119, and 161, respectively, and the collection cyclones 300G, 300M, and A step of introducing into 300F, a step of removing ultrafine powder from the coarse powder group G by the common bag filter 400 in the collection cyclone 300G, and sending the remaining coarse powder G ′ to a pulverizer, and a common bag in the collection cyclone 300M The process of removing the ultrafine powder from the coarse powder group M by the filter 400 and collecting the remaining medium powder M ′ as a powder having a desired particle size, and the ultrafine powder from the fine powder group F by the common bag filter 400 in the collection cyclone 300F A classifying system comprising: a step of removing and collecting the remaining fine powder F ′ and sending it to a kneader.
(4) The coarse powder group G, the medium powder group M, and the fine powder group F classified by the classification device according to (1) are discharged from the discharge paths 118, 119, and 161, respectively, and the collection cyclones 300G, 300M, and A step of introducing into 300F, a step of removing ultrafine powder from the coarse powder group G by the common bag filter 400 in the collection cyclone 300G, and sending the remaining coarse powder G ′ to a pulverizer, and a common bag in the collection cyclone 300M The step of removing ultrafine powder from the coarse powder group M by the filter 400 and collecting the remaining medium powder M ′ as a powder having a desired particle size, and the common bag filter 400 and the dedicated bag filter 500 in the collection cyclone 300F A step of removing ultrafine powder from the fine powder group F, collecting the remaining fine powder F ′ and sending it to a kneader. Grade system.
(5) The classification system according to (3) or (4), which is used for classification of electrophotographic toner.

  ADVANTAGE OF THE INVENTION According to this invention, it is a classification apparatus using inertia force, Comprising: The classification apparatus and classification system which can acquire the highly accurate classification effect can be provided.

  Moreover, according to this invention, the classification apparatus and classification system which can implement | achieve a yield increase and cost reduction by a highly accurate classification effect can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, the structure of the classification apparatus of this invention is demonstrated using FIGS. 1-3.

  FIG. 1 is a side sectional view of the classification device of the present invention, FIG. 2 is a schematic front view of the classification rotor of the present invention and its periphery, and FIG. 3 is a diagram showing an example of the classification rotor of the present invention. (a) is the front schematic which showed only one slit, (b) is the sectional view on the AA line in (a).

  In addition, the same code | symbol is attached | subjected about the structure same as the structure already demonstrated by background art, and the detailed description is abbreviate | omitted.

101b is a classification chamber, 122 is a wall, 123 is an arc-shaped Coanda portion provided so as to protrude into the classification chamber 101b, and 151 is a cylindrical classification rotor having a hollow cylindrical shape, that is, an internal space 154, The classification rotor 151 has a slit 153 penetrating toward the internal space 154 in the entire outer peripheral surface.
In the present invention, the arc-shaped Coanda portion 123 that generates the Coanda effect includes a classification rotor 151 and a wall 122. The classification rotor 151 is disposed at the tip of the wall 122.
The classifying rotor 151 draws a powder material having a particle diameter equal to or smaller than a predetermined diameter into the internal space 154 through the slit 153 as a fine powder group F according to the width, shape, and other conditions of the slit 153, and has a particle diameter larger than the predetermined diameter. Can be classified as a medium powder group M and a coarse powder group G to the outside of the classification rotor 151. The classifying rotor 151 can be rotated by adjusting the speed by the motor 152.

Reference numeral 152 denotes a motor for rotation, 153 denotes a slit, 154 denotes an internal space of the classification rotor 151, 155 denotes a rotation shaft, 161 denotes a discharge path, and 170b denotes a classification device.
An example of the classification rotor 151 will be described with reference to FIG. In FIG. 3A, only one slit 153 is shown for explanation. (B) is the sectional view on the AA line in (a).
In the example of FIG. 3, 34 slits 153 are provided on the circumferential surface of the classification rotor 151 having a diameter of 54 mm. The slit 153 preferably has a width of about 2 to 4 mm, a longitudinal length of about 40 to 50 mm, and a depth of about 7 mm. The classification rotor 151 preferably has a single-supported rotating shaft 155 at the center.
The classifying rotor 151 of the present invention is not limited to this.

The classification chamber 101b includes walls 111 to 114, an inlet edge 112t, a classification edge 114t, and a Coanda portion 123.
The classification device 170b includes a classification chamber 101b, a powder raw material supply unit 130, a motor 152, and a discharge path 161.

  The space between the wall 114 and the wall 122 is used as the discharge path 119.

  The internal space 154 of the classification rotor 151 is communicated with a discharge path 161, and the discharge path 161 is communicated with a dedicated bag filter 500 via a collection cyclone 300F as will be described later.

  Therefore, the internal space 154 can be depressurized by the blower provided in the dedicated bag filter 500, whereby the fine powder group F can be drawn into the internal space 154 through the slit 153 of the classification rotor 151.

  In addition, a powder raw material supply pipe 131 is inserted between the wall 122 and the wall 111. At that time, the powder raw material supply pipe 131 is disposed so that the tip of the powder raw material supply pipe 131 comes close to the classification rotor 151 and the classification edge 114t.

With the above configuration, the classification rotor in a state where the airflow from the inlet passages 116 and 117 and the solid-gas mixed flow from the powder raw material supply pipe 131 are merged and the solid-gas mixed flow is swirled along the classification rotor 151. While rotating 151 in the direction of the arrow in FIG. 1, the internal space 154 is decompressed by a blower provided in the dedicated bag filter 500.
Thus, while preventing the powder raw material from adhering to the classification rotor 151 by rotation, the inertial force based on the size of the powder raw material particles, the centrifugal force of the curved airflow due to the Coanda effect, the acceleration force due to the catapult effect, the classification rotor 151 The suction force to the inner space 154 is applied.
Then, the fine powder group F is drawn into the internal space 154 of the classification rotor 151 to the discharge path 161, the medium powder group M is repelled by the classification rotor 151, the classification edge 114t is used to the discharge path 119, and the coarse powder group G is classified by inertial force or the like. Classification can be made to the discharge path 118 by the edge 114t.

  The classification accuracy at this time includes the position of the classification edge 114t, the rotational speed, position, and size of the classification rotor 151, the position of the intake edge 112t, the flow rate of the airflow from the intake paths 116 and 117, and the powder raw material supply pipe 131. However, in the present invention, the rotational speed of the classifying rotor 151, which has a particularly large effect, can be adjusted by the motor 152 in accordance with the powder raw material, and the classification of the slits 153 is different. By appropriately selecting the rotor 151, highly accurate classification can be performed.

In addition, it is under unified management by the common bag filter 400 that the strength of drawing the fine powder group F into the internal space 154 and the strength of drawing the ultrafine powder into the common bag filter 400 at the same time are appropriate. Although it is difficult, as will be described later, the strength of each pull-in can be freely adjusted by providing a dedicated bag filter 500, so that more accurate classification can be performed by adjusting according to the conditions. Become.
In the present embodiment, the collection cyclone 300F communicates with the common bag filter 400 and the dedicated bag filter 500, but the communication with the common bag filter 400 is disconnected and only the dedicated bag filter 500 communicates. It can also be configured as follows.

  Then, the classified fine powder group F, medium powder group M, and coarse powder group G are discharged from the discharge paths 161, 119, and 118, respectively.

  Next, the classification system of the present invention will be described with reference to FIG.

  FIG. 4 is a diagram showing a classification system of the present invention.

  In addition, the same code | symbol is attached | subjected about the structure same as the structure already demonstrated by background art, and the detailed description is abbreviate | omitted.

  Reference numeral 500 denotes a dedicated bag filter for decompressing the internal space 154 of the classifying rotor 151. The degree of decompression of the internal space 154 can be adjusted by the blower provided in the dedicated bag filter 500.

  The classifier 200b includes a jet nozzle 102 and a classifier 170b.

  Next, the classification operation of the powder raw material by the classification system of the present invention will be described.

  First, as shown in FIG. 4, the coarse powder group G, the medium powder group M, and the fine powder group F classified by the classifier 200b are discharged from the discharge paths 118, 119, 161, and the collection cyclones 300G, 300M, Introduced at 300F.

  In the collection cyclone 300G, the superfine powder is removed from the coarse powder group G by the common bag filter 400, and the remaining coarse powder G 'is collected and sent to a pulverizer (not shown).

  In the pulverizer, after pulverization, the pulverized product is again sent to the classifier 200b as a powder raw material.

  In the collection cyclone 300M, the ultrafine powder is removed from the medium powder group M by the common bag filter 400, and the remaining medium powder M 'is recovered as a powder (product) having a desired particle size.

  In the collection cyclone 300F, the ultrafine powder is removed from the fine powder group F by the common bag filter 400 and the dedicated bag filter 500, and the remaining fine powder F ′ is collected and sent to a kneading machine (not shown). Reuse as raw material by mixing.

In the common bag filter 400 and the dedicated bag filter 500, the ultrafine powder is collected and discarded or reused.
The ultra fine powder is often a small piece of material constituting the outer periphery of the powder raw material, and most of it is, for example, wax of an internal additive.
Therefore, in the case of reuse, it cannot be used as it is with the raw material for melt-kneading, and it is used as a chemical for component adjustment within a certain limit.

Next, a classification system that does not have the dedicated bag filter 500 will be described.
In this case, the degree of decompression of the internal space 154 is adjusted by the common bag filter 400.
Accordingly, the degree of decompression of the internal space 154 is adjusted by the blower provided in the common bag filter 400 together with the strength of drawing in the ultrafine powder, and the dedicated bag filter 500 is provided in terms of high accuracy. Is preferred.
However, since the dedicated bag filter 500 is not provided, the classification system can be simplified, and the cost can be reduced.
As described above, when the dedicated bag filter 500 is provided or not provided, there are advantages in each case, and the bag filter 500 can be properly used depending on the situation.

  The powder raw material to which the classification system of the present invention can be applied is not particularly limited, and examples thereof include electrophotographic toner or colored resin powder used for image formation by electrophotography.

  This toner for electrophotography or colored resin powder is produced mainly by melt-kneading a mixture of a binder resin and a colorant, cooling the melt-kneaded product, and classifying it. The greatest consideration is given to the particle size distribution in order to maintain good results.

  In order to obtain a product having the optimum particle size distribution necessary for such an electrophotographic toner, it is necessary to accurately limit various classification conditions and to remove coarse powder and fine powder with high precision. The classifier is particularly effective for this purpose.

  As described above, according to the present invention, a classifying device using inertial force can obtain a highly accurate classification effect, particularly a highly accurate classification effect in a small particle size (5 to 7 μm), and a sharp particle size. A classification device and a classification system capable of obtaining a powder having a distribution can be provided.

  In addition, by using the classification rotor 151, it is possible to provide a classification device and a classification system that prevent adhesion of fine powder and can obtain a highly accurate classification effect for a long period of time without maintenance.

  Further, according to the present invention, it is possible to provide a classification device and a classification system that can increase the yield due to a highly accurate classification effect and can realize cost reduction in the reuse process.

  Further, according to the present invention, it is possible to provide a classification device and a classification system that do not require repeated classification in order to obtain a sharp particle size distribution and can obtain a stable classification effect.

Side sectional view of the classification device of the present invention Schematic front view of the classification rotor of the present invention and its periphery It is a figure which shows an example of the classification rotor of this invention, Comprising: (a) is the front schematic which showed only one slit, (b) is the sectional view on the AA line in (a). The figure which shows the classification system of this invention Side sectional view of a conventional inertial force classifier Diagram showing a conventional classification system

Explanation of symbols

101a, 101b Classification chamber 111-115 Wall 112t Inlet edge 114t, 115t Classification edge 116, 117 Inlet path 118-120 Discharge path 121 Coanda block 122 Wall 123 Coanda section 130 Powder raw material supply section 131 Powder raw material supply pipe 132 Hopper 151 Classifying rotor 152 Motor 153 Slit 154 Internal space 161 Discharge path 170a, 170b Classifying device 200a, 200b Classifier 300G, 300M, 300F Collection cyclone 400 Common bag filter 500 Dedicated bag filter

Claims (5)

A powder raw material supply pipe for ejecting a solid-gas mixed flow comprising an air flow and a powder raw material;
An arc-shaped Coanda portion arranged so that the tip comes near the tip of the powder raw material supply pipe;
A classification edge for classifying the powder raw material;
An inlet path for introducing airflow into the classification chamber;
A classification device including a discharge path for discharging the classified powder out of the classification chamber;
The classifier is characterized in that the tip of the Coanda part is a cylindrical classifying rotor having an internal space, and the classifying rotor has slits penetrating toward the internal space in the entire outer peripheral surface. The classification device according to claim 1, wherein the classification device is used for classification of toner for electrophotography. The coarse powder group G, the medium powder group M, and the fine powder group F classified by the classification device according to claim 1 are discharged from the discharge passages 118, 119, and 161, respectively, and introduced into the collection cyclones 300G, 300M, and 300F. The process, the step of removing ultrafine powder from the coarse powder group G by the common bag filter 400 in the collection cyclone 300G, and sending the remaining coarse powder G ′ to the pulverizer, and the coarse filter by the common bag filter 400 in the collection cyclone 300M The step of removing the ultrafine powder from the powder group M and recovering the remaining medium powder M ′ as a powder having a desired particle size, and the ultrafine powder from the fine powder group F are removed by the common bag filter 400 in the collection cyclone 300F. A classification system comprising: a step of collecting fine powder F ′ and sending it to a kneader. The coarse powder group G, the medium powder group M, and the fine powder group F classified by the classification device according to claim 1 are discharged from the discharge passages 118, 119, and 161, respectively, and introduced into the collection cyclones 300G, 300M, and 300F. The process, the step of removing ultrafine powder from the coarse powder group G by the common bag filter 400 in the collection cyclone 300G, and sending the remaining coarse powder G ′ to the pulverizer, and the coarse filter by the common bag filter 400 in the collection cyclone 300M The step of removing ultrafine powder from the powder group M and collecting the remaining medium powder M ′ as a powder having a desired particle size, and the common bag filter 400 and the dedicated bag filter 500 in the collection cyclone 300F from the fine powder group F. A step of removing ultrafine powder, collecting the remaining fine powder F ′ and sending it to a kneader. Stem. 5. The classification system according to claim 3, wherein the classification system is used for classification of electrophotographic toner.

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