JP2004057843A - Classifier and production method of toner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a classifier which enhances the efficiency of dispersion in its dispersion chamber, highly efficiently separates particles in the range of required sizes and enhances the recovery of a product, and to provide a production method using the classifier. <P>SOLUTION: A deposition prevention means 11 having a rugged shape is disposed on the upper part of a conical member 7 and a ring-like member 12 is disposed on the lower part of the conical member 7. The ring-like member 12 can be disposed in a plurality of number and the thickness and diameter can be changed in accordance with classification conditions. A deposition preventing means 11 and the ring-like member 12 are attachable and detachable with respect to the conical member 7. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a classifier used for producing a dry toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, and relates to a particle sieve for obtaining a desired particle size. The present invention relates to a classification device for performing classification and a method for producing a toner using the classification device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a classifier for separating a micron-order powder material into a coarse powder and a fine powder includes a cylindrical dispersion chamber and a classification chamber. A conical member is provided between the dispersion chamber and the classifying chamber, and the powder material is supplied from an opening at one end of the upper outer surface of the dispersion chamber, and is subjected to a dispersion action by a swirling flow formed inside the dispersion chamber. Further, the powder is guided to the classifying chamber and discharged to a fine powder discharge port or a coarse powder discharge port by centrifugal separation, whereby the powder material is separated into coarse powder and fine powder.
[0003]
FIG. 8 is a cross-sectional view showing a configuration of a conventional classification device. The classifier shown in FIG. 8 includes a supply pipe 1 through which inflow air as primary transport air and a powder material are supplied, an exhaust pipe 2 through which ultrafine powder is discharged together with air, a dispersion chamber 3, and a dispersion chamber 3. An air inlet 4, which is a secondary conveying air fed to the air, a fine powder outlet 5 for discharging fine powder with air, a coarse powder outlet 6 for discharging coarse powder with air, and a lower portion of the dispersion chamber 3. A conical member 7 for increasing the swirling flow field in the dispersion chamber 3, a classifying plate 8 provided below the conical member 7, and a classifying chamber 9 defined by the conical member 7 and the classifying plate 8. ing. In addition, the whole classification apparatus main body consists of a substantially cylindrical housing.
[0004]
Next, the operation of the conventional classifier shown in FIG. 8 will be described.
First, air is supplied from the supply pipe 1 and the air inlet 4, and at the same time, air is discharged from the exhaust pipe 2, the fine powder discharge port 5, and the coarse powder discharge port 6. , A swirling flow field is formed. There, the powder material is supplied together with air from the supply pipe 1, guided into the dispersion chamber 3, and falls while rotating while undergoing centrifugal action by the swirling flow field of air. At this time, the ultrafine powder having a very small particle size among the powder materials is guided toward the center of the dispersion chamber 3 and discharged from the exhaust pipe 2 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 3 passes through the annular gap A and is guided to the classification chamber 9, where the powder material is also subjected to the centrifugal separation operation. From the center of the classifying chamber 9, passing through the annular gap B between the classifying plate 8 and each inner wall surface of the classifying chamber 9, from the coarse powder discharge port 6 communicating with a suction device (not shown) such as a suction fan or the like. Is discharged. On the other hand, the fine powder is guided to the center of the classification chamber 9 by centripetal force, and is discharged from the fine powder discharge port 5 communicating with a suction device (not shown) such as a suction fan.
[0005]
[Problems to be solved by the invention]
However, in the conventional classifier as described above, when the classifier is operated continuously, the supplied powder material is supplied to the upper surface of the conical member provided between the dispersion chamber and the classifier. May accumulate. This is one of the causes for lowering the product recovery rate for the supplied powder material. Further, the accumulation of the powder material on the upper surface of the conical member may disturb the airflow in the dispersion chamber or narrow the gap between the dispersion chamber and the classification chamber, thereby lowering the classification accuracy. There is also a problem that this will happen.
In addition, a flow with distribution is formed inside the classification chamber of the classification device, and the speed is particularly high near the lower wall surface of the conical member compared to other places, so it is collected to the coarse powder collection side. There is also a problem that the powder material to be performed is guided to the fine powder collecting side in the center of the classification device, and the classification accuracy is reduced.
[0006]
In order to solve these problems, the present inventors disclose a technique in which a step is provided on a conical member, for example, in Japanese Patent Application Laid-Open No. 2000-218236.
[0007]
The present invention is intended to solve these problems, and achieves improved dispersion efficiency in the dispersion chamber of the classifier, separates particles in a required size range with high efficiency, and improves the product recovery rate. An object of the present invention is to provide an improved classifier and a method for producing a toner using the same.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention according to claim 1 provides a dispersion chamber for dispersing a powder material, and a powder material provided continuously below the dispersion chamber and flowing from the dispersion chamber by centrifugal classification. Classifying chamber, a conical member for dividing the classifying chamber and the classifying chamber, and a classifying plate for classifying the classifying chamber, and are supplied together with carrier air from a powder material supply port provided in the upper part of the classifying chamber. The powder material is classified into ultrafine powder and fine powder by the swirling flow inside the dispersion chamber, the ultrafine powder is discharged, and the powder material guided to the classification chamber is classified into coarse powder and fine powder by centrifugal separation. In a classifier for discharging coarse powder, the classifier is provided with a deposition preventing means above the conical member.
According to a second aspect of the present invention, there is provided the classification device according to the first aspect, wherein the accumulation preventing means has an uneven shape on an upper portion.
According to a third aspect of the present invention, there is provided the classification device according to the first or second aspect, wherein the accumulation preventing unit is detachable from the conical member.
[0009]
The present invention according to claim 4 is the classification device according to any one of claims 1 to 3, wherein the classification device includes a ring-shaped member below the conical member.
According to a fifth aspect of the present invention, there is provided the classification device according to the fourth aspect, wherein a plurality of the ring-shaped members are provided.
According to a sixth aspect of the present invention, there is provided the classification device according to the fourth or fifth aspect, wherein the ring-shaped member varies a thickness and a diameter according to a classification condition.
The present invention according to claim 7 is the classification device according to any one of claims 4 to 6, wherein the ring-shaped member is detachable from the conical member.
[0010]
According to an eighth aspect of the present invention, in the method for producing a toner used in an electrophotographic image forming apparatus, after the powder material is pulverized, the classification is performed by the classification apparatus according to any one of the first to seventh aspects. And a method for producing a toner.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The classifier 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 dispersion action by a swirling flow formed inside the dispersion chamber to discharge ultrafine powder, Further, the powder material is guided to a classification room, and the powder material is classified into coarse powder and fine powder by centrifugal separation. The accumulation preventing means provided in the dispersion chamber can change the velocity distribution of the upper part of the conical member, thereby making it difficult for the powder material to accumulate on the upper part of the conical member, thereby improving the dispersion efficiency in the dispersion chamber. can do.
[0012]
FIG. 1 is a cross-sectional view illustrating a configuration of a classification device according to an embodiment of the present invention. The classifier according to the present invention has the accumulation preventing means 11 at the upper part of the conical member 7 and the ring-shaped member 12 at the lower part. As shown in FIG. 1, the accumulation preventing means 11 is installed above the conical member 7 so as to be rotated by a swirling flow formed inside the dispersion chamber 3. With this setting, when the powder material supplied to the dispersion chamber 3 descends while rotating in the dispersion chamber 3 and is guided to the classification chamber 9, the accumulation preventing means 11 is disposed inside the dispersion chamber 3. This prevents the powder material from being deposited on the upper part of the conical member 7. That is, the provision of the accumulation preventing means 11 causes the accumulation preventing means 11 to rotate, the velocity distribution in the upper part of the conical member 7 changes, the flow in the rotational direction becomes stronger, and the powder Material is less likely to deposit. Therefore, the dispersion efficiency in the dispersion chamber 3 is improved, and classification with high accuracy is possible.
[0013]
FIG. 2 is a plan view of the accumulation preventing means 11, and FIG. 3 is a side sectional view of the conical member 7.
The deposition preventing means 11 is detachable from the conical member 7 by a detachment mechanism 13. Accordingly, it is possible to easily cope with a change in conditions such as the processing amount of the powder material and the average particle diameter, and it is possible to shorten the switching time. Although the shape of the accumulation preventing means 11 is not particularly limited, a blade shape in which the unevenness portion 10 receives a flow in the turning direction and the accumulation preventing means 11 rotates is preferable.
In addition, since the speed near the lower wall surface of the conical member 7 is higher than that of other places, as shown in FIG. 3, by providing the ring-shaped member 12 below the conical member 7, (7) The flow along the lower wall surface is changed to prevent the powder material to be recovered to the coarse powder recovery side from being guided to the fine powder recovery side and to reduce the classification accuracy. The shape of the ring-shaped member 12 is not particularly limited, but is preferably a perfect circle.
[0014]
As shown in FIG. 4, by providing a plurality of ring-shaped members 12, the flow along the wall surface is further changed, and the powder material having a particle diameter to be guided to the coarse powder collection side is guided to the fine powder collection side. The effect can be further prevented.
[0015]
FIG. 5 is a diagram illustrating the height h of the ring-shaped member 12 with respect to the classification chamber 9. As shown in FIG. 5, the height h of the ring-shaped member 12 is preferably equal to or less than の of the height H of the classifying chamber 9. This is because if the height h of the ring-shaped member 12 is too high, the flow inside the classification chamber 9 changes greatly, and a problem such as a reduction in the recovery rate of the powder material occurs. is there. In addition, the height h of the ring-shaped member 12 can be changed according to classification conditions.
[0016]
FIG. 6 is a diagram showing a configuration of the ring-shaped member 12 with respect to the conical member 7. As shown in FIG. 6, the thickness d of the ring-shaped member 12 is preferably 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 large, as in the case of the height condition, the flow inside the classification chamber 9 greatly changes, and a problem such as a reduction in the recovery rate of the powder material occurs. This is to prevent this. In addition, the thickness d of the ring-shaped member 12 can be changed according to classification conditions.
Further, the diameter b of the ring-shaped member 12 is preferably equal to or larger than the diameter c of the lower convex portion of the conical member 7. This is because, even if the diameter is set to be equal to or less than the diameter c of the lower convex portion of the conical member 7, the flow along the wall surface does not change significantly, and as a result, the movement of the powder material hardly changes. This is because a powder material having a particle diameter to be guided cannot obtain an effect of preventing an action guided to the fine powder recovery side.
[0017]
Further, as shown by an arrow e in the figure, it is preferable that the outer side and / or the inner side of the upper part of the ring-shaped member 12 is a curved part. This is because the flow tends to stagnate at the mounting portion where the ring-shaped member 12 is provided below the conical member 7, and the powder material is easily deposited in continuous operation, the recovery rate is reduced, and the cleaning property is poor. This is for preventing such troubles as becoming.
[0018]
Furthermore, by attaching the ring-shaped member 12 shown in FIG. 7 to the conical member 7 by the detachment mechanism 14, for example, screwing, the attachment becomes easy, and the switching work of the ring-shaped member 12 can be shortened. Adjustment of height and width becomes easy.
[0019]
Furthermore, by classifying and manufacturing the toner using the above-described classifier, the classification accuracy of the obtained toner is improved, and the quality of the toner can be improved.
[0020]
【Example】
Next, a specific example according to an example of the present embodiment will be described. It should be noted that the present invention is not limited to the following embodiments, and it goes without saying that various modifications and substitutions can be made within the scope of the claims.
A mixture of 85 parts by weight of a styrene-acrylic copolymer resin and 15 parts by weight of carbon black was melt-kneaded, cooled, coarsely ground with a hammer mill, and then finely ground with a jet mill. Classification was performed by a classification device having the configuration shown.
[0021]
Classification accuracy test (Example 1)
The powder material having the above composition is supplied to a classifier having a deposition preventing means provided above the conical member, the exhaust blower pressure is set to 15.9 kPa (1620 mmAq), and the number of the convex blades of the deposition preventing means is set to eight. The powder was classified so that a powder having a volume average particle diameter of 7.5 μm (measured by a Coulter counter) could be recovered, and the volume average particle diameter was 7.30 μm and 4 μm or less for a feed amount of 10.5 kg / h. The fine powder content (% by weight) was 6.61%, and the coarse powder content (% by weight) of 12.7 μm or more was 2.05%, and a sharp particle size distribution was obtained.
[0022]
(Example 2)
The powder material having the above composition is supplied to a classification device having a ring-shaped member provided below the conical member, the exhaust blower pressure is 15.9 kPa (1620 mmAq), and the height h of the ring-shaped member is set to the classification chamber height H. About 1/20, the thickness d of the ring-shaped member was set to 1.5 mm, and the diameter b was set to 170 mm. As a result, with respect to the feed amount of 10.5 kg / h, the content of fine powder having a volume average particle size of 7.50 μm and 4 μm or less (% by weight) 4.50%, and the content of coarse powder having a volume average particle size of 12.7 μm or more (% by weight) 2.52%, and a sharp particle size distribution was obtained.
[0023]
(Example 3)
The powder material having the above composition was supplied to a classifier having two ring members provided below the conical member, and the diameter b of the ring members was set to 170 mm and 150 mm, and the other conditions were the same as in Example 1. did. As a result, with respect to the feed amount of 10.5 kg / h, the content of fine powder having a volume average particle size of 7.55 μm and 4 μm or less (% by weight) 4.07, and the content of coarse powder having a content of 12.7 μm or more (% by weight) 2 .60%, and a sharp particle size distribution was obtained.
[0024]
(Comparative example)
The powder material having the above composition is supplied, the exhaust blower pressure is set to 15.9 kPa (1620 mmAq) using a conventional classifier having the configuration shown in FIG. 8, and the volume average particle size is 7.5 μm (measured by a Coulter counter). Classification was performed so that the powder of the above could be recovered. As a result, for a feed amount of 10.5 kg / h, the content of fine powder having a volume average particle size of 7.15 μm and 4 μm or less (% by weight) 10.87%, and the content of coarse powder having a volume average particle size of 12.7 μm or more (% by weight) 1.30%, and a sharper particle size distribution was not obtained as compared with Examples 1 to 3.
[0025]
Cleanability by the Shape of the Ring Member The powder material having the above composition was supplied to a classifier provided with a ring member below the conical member, and the upper outside of the ring member was formed into a curved surface. It processed on the same conditions as. As a result, the accumulation of the powder material in the lower attachment portion of the conical member was reduced, and the cleaning property was also improved.
[0026]
The powder material having the above composition was supplied to a classification device having a ring-shaped member provided below the conical member, and the inside of the upper portion of the ring-shaped member was formed into a curved surface. As a result, the accumulation of the powder material in the lower attachment portion of the conical member was reduced, and the cleaning property was also improved.
[0027]
The powder material having the above composition is supplied to a classifying apparatus in which the deposition preventing means is provided on the upper part of the conical member having a cleaning property by detaching the member, and the deposition preventing means 11 is detachable. After processing, a cleaning switch was performed. As a result, the cleaning switching time can be reduced by about 10% as compared with the first embodiment.
[0028]
The powdery material having the above composition is supplied to a classifier having a ring-shaped member provided below the conical member, and the ring-shaped member 12 is detachable. Was carried out. As a result, the cleaning switching time can be reduced by about 15% as compared with the first embodiment.
[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the powder material from being deposited on the upper portion of the conical member by providing the upper portion of the conical member with the deposition prevention unit that rotates by the swirling flow, A classifier with improved classification accuracy can be provided.
Further, by providing the ring-shaped member below the conical member, the flow in the lower part of the conical member can be changed, and a classifier having improved classification can be provided.
Further, by varying the thickness and the diameter of the ring-shaped member according to the classification conditions, it is possible to provide a classification device that can flexibly respond to the classification conditions.
Further, by making the deposition preventing means and the ring-shaped member detachable, it is possible to easily cope with a change in conditions such as a processing amount of powder material, an average particle diameter, etc., thereby improving cleanability and reducing switching time. It is possible to provide a classifying device that can be used.
Further, by using the classifier for the production of a toner, it is possible to provide a toner production method capable of obtaining a high quality toner having a sharp particle size distribution.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a classification device according to an embodiment of the present invention.
FIG. 2 is a plan view of a deposition preventing unit.
FIG. 3 is a side sectional view showing a configuration of a conical member.
FIG. 4 is a side sectional view showing a configuration of a plurality of ring-shaped members.
FIG. 5 is a view showing a height h of a ring-shaped member with respect to a classifying chamber 9;
FIG. 6 is a diagram showing a configuration of a ring-shaped member with respect to a conical member.
FIG. 7 is a partial cross-sectional view showing a mounting portion of a ring-shaped member.
FIG. 8 is a cross-sectional view showing a configuration of a conventional classification device.
FIG. 9 is a cross-sectional view showing a configuration of a conical member in a conventional classifier.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Supply pipe 2 Exhaust pipe 3 Dispersion chamber 4 Air inflow port 5 Fine powder discharge port 6 Coarse powder discharge port 7 Conical member 8 Classification plate 9 Classification chamber 10 Convex part (recess)
DESCRIPTION OF SYMBOLS 11 Deposition prevention means 12 Ring-shaped members 13 and 14 Detachment mechanism

Claims (8)

A dispersion chamber for dispersing the powder material, a classification chamber that is provided continuously below the dispersion chamber and classifies the powder material flowing from the dispersion chamber by centrifugal classification, and a conical member that partitions the dispersion chamber and the classification chamber. , Having a classification plate for partitioning the classification room,
The powder material supplied along with the carrier air from the powder material supply port provided in the upper part of the dispersion chamber is classified into ultrafine powder and fine powder by the swirling flow inside the dispersion chamber, and the ultrafine powder is discharged. In a classifier that classifies the guided powder material into coarse powder and fine powder by centrifugation and discharges the coarse powder,
The classifier is characterized in that the classifier is provided with a deposition preventing means above the conical member. 2. The classification device according to claim 1, wherein the accumulation preventing means has an uneven shape on an upper part. The classification device according to claim 1, wherein the accumulation preventing unit is detachable from the conical member. The classification device according to any one of claims 1 to 3, wherein the classification device includes a ring-shaped member below the conical member. The classifier according to claim 4, wherein a plurality of the ring-shaped members are provided. The classifier according to claim 4, wherein the ring-shaped member has a thickness and a diameter that are variable according to a classification condition. The classifier according to any one of claims 4 to 6, wherein the ring-shaped member is detachable from the conical member. In a method for producing a toner used in an electrophotographic image forming apparatus,
A method for producing a toner, comprising: pulverizing a powder material; and then classifying the powder material with the classifier according to claim 1 to produce a toner.

Images