JP4287173B2 - Counter jet mill type pulverizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a counter jet mill type pulverization classifier used in a fine pulverization step after mixing, kneading, cooling, and coarse pulverization of toner raw materials in the production process of an electrophotographic toner. The counter jet mill type pulverization classifier is not limited to the process for producing electrophotographic toner, but is not limited to the toner production process. Mineral raw materials such as talc, lime, ceramic, resin, cosmetics, dyes, herbal medicine, and chemical products. It can be applied to a grinding system for materials such as chemicals.
[0002]
[Prior art]
[Patent Document 1]
JP 2000-107626 A [Patent Document 2]
JP 2000-117137 A [Patent Document 3]
Japanese Patent No. 2528348 gazette
A fluidized bed jet crusher comprising at least a crushing chamber having a central axis, a collision member installed in the crushing chamber, and a nozzle for injecting high-speed gas toward the collision member, wherein the nozzles are installed in multiple stages In addition, there has been proposed a fluidized bed jet pulverizer characterized in that the upper nozzle and the lower nozzle do not overlap when the nozzle is viewed from directly above (Patent Document 1).
[0004]
A fluidized bed jet pulverizer comprising at least a pulverization chamber having a central axis, a collision member installed in the pulverization chamber and having a center on the central axis of the pulverization chamber, and a nozzle for injecting high-speed gas toward the collision member 6 or more nozzles having an S / N of 5000 to 15000 when the cross-sectional area of the crushing chamber is S (mm ² ) and the cross-sectional area of the nozzle is N (mm ² ) are installed. A fluidized bed jet pulverizer is proposed (Patent Document 2).
[0005]
In an airflow type pulverizer provided with a raw material supply pipe on the side wall of the pulverization chamber and provided with a plurality of pulverization nozzles below the supply pipe, the pulverization nozzle is disposed in a substantially central direction in the horizontal plane of the pulverization chamber. In addition, a center core having a large mass is erected at the center position of the pulverizing chamber, and the raw material in the pulverizing chamber is accelerated by the jet air current ejected from the pulverizing nozzle and collides with the center core to be pulverized. Has been proposed (Patent Literature 3).
[0006]
[Problems to be solved by the invention]
The conventional counter-jet mill type pulverization classifier accelerates along with the objects to be pulverized around the nozzles when discharging the jet stream from the nozzles facing each other in the lower part of the fluidized bed. The pulverized material to be crushed is discharged outside the machine by the centrifugal classification mechanism arranged at the top, and the large sized object remains in the machine. Thus, the structure is re-pulverized again by the lower pulverizing section. However, in the current pulverized classification air, the pulverized material that has been pulverized in the lower part and reduced in particle size is not efficiently moved to the classification part due to turbulence in the fluidized bed, and does not reach the classification part. For this reason, even when the particle size to be discharged to the outside of the machine is reached, it cannot be discharged properly. As a result, the production capacity is reduced and the yield of the appropriate particle size is reduced.
[0007]
[Means for Solving the Problems]
The present invention provides a counter jet mill type pulverizing and classifying machine configured to have at least a pulverizing jet nozzle and a classifying rotor that are disposed opposite to each other in the pulverizing chamber. I was able to solve it.
That is, by providing the inner cylinder in the pulverization chamber, the inner cylinder can prevent the turbulence of the airflow in the fluidized bed and exert the effect of convection, so that the object to be pulverized can be efficiently classified. Since it can move and undergo classification processing, it can reduce over-pulverization and improve production efficiency.
[0008]
As the pulverizing jet nozzle and the classifying rotor, those conventionally used in counter jet mill type pulverizing and classifying machines are used.
Further, in the counter jet mill type pulverizing / classifying machine, by providing the inner cylinder as described above, the object to be crushed is more forcibly conveyed to the classifying unit, whereby the object to be crushed enters the classification rotor at an initial speed. A lot of things will cause the classification accuracy to deteriorate. For this reason, it is preferable to install a shielding plate under the classification rotor. By installing the shielding plate, the flow from the convection at the lower part of the fluidized bed toward the center of the classification rotor is reduced, and as a result, the classification accuracy is improved and the discharge of unmilled particle size (large particle size) powder is reduced. Production efficiency can be improved.
The shielding plate is installed in the lower part of the classification rotor, but it is preferable to provide the shielding plate corresponding to each rotor. For example, the shielding plate is four for a four-rotor type pulverizing and classifying machine and three for a three-rotor type pulverizing and classifying machine.
Further, in order to simplify the structure of the counter jet mill type pulverizing / classifying machine, it is preferable that the shielding plate also serves as a holder installed in the inner cylinder.
[0009]
Furthermore, it is preferable that the counter jet mill type pulverization classifier satisfies the requirements of the following formulas (1) to (5).
1stly, the said inner cylinder is installed in the said nozzle upper part, and the length H2 of this inner cylinder satisfies the requirements of the following Formula (1).
1/3 H1 ≦ H2 ≦ 2/3 H1 (1)
(H1: Height between classification rotor center line CD and grinding nozzle center line AB)
The counter jet mill type pulverizing and classifying machine of the present invention can satisfy the above requirement (1), thereby allowing the pulverized material to reach the classification part more accurately and efficiently undergo the classification process. The effect of reducing pulverization and improving production efficiency is achieved.
[0010]
Second, the distance H3 from the lower part of the inner cylinder to the center line AB of the pulverizing nozzle satisfies the requirement of the following expression (2).
50mm ≤ H3 ≤ 150mm ... (2)
The counter jet mill type pulverizing and classifying machine of the present invention can satisfy the above requirement (2), thereby allowing the pulverized material to reach the classification part more accurately and efficiently performing the classification process. The effect of reducing pulverization and improving production efficiency is achieved.
[0011]
Thirdly, the diameter H5 of the inner cylinder satisfies the requirement of the following formula (3).
1/3 H4 ≦ H5 ≦ 2/3 H4 (3)
(H4: Inner diameter of pulverizer body)
The counter jet mill type pulverizing and classifying machine of the present invention satisfies the requirement (3), so that the pulverized material to be pulverized can reach the classification part more accurately and can be subjected to an efficient classification process. The effect of reducing pulverization and improving production efficiency is achieved.
[0012]
Fourth, the counter jet mill type pulverizing and classifying machine, wherein the width H6 of the shielding plate satisfies the requirement of the following formula (4).
1/3 H7 ≦ H6 ≦ H7 (4)
(H7: Diameter of classification rotor)
By satisfying the requirement (4), the counter jet mill type pulverization classifier of the present invention reduces the rush flow toward the center of the classification rotor, improves the classification accuracy, and improves the accuracy of the unmilled particle size (large particle size) powder. The effect of reducing emissions and improving production efficiency is achieved.
[0013]
Fifth, a counter jet mill type pulverizing and classifying machine characterized in that a distance H8 between the lower limit of the classifying rotor and the shielding plate satisfies the requirement of the following formula (5).
1/4 H7 ≦ H8 ≦ H7 (5)
(H7: Diameter of classification rotor)
The counter jet mill type pulverizing / classifying machine according to the present invention has the effect that the structure of the counter jet mill type pulverizing / classifying machine can be simplified by satisfying the requirement (5) so that the shielding plate also serves as a holder for the inner cylinder. Is played.
[0014]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
Reference example 1
A mixture of 75% by weight of a polyester resin, 10% by weight of a styrene acrylic copolymer resin and 15% by weight of carbon black is melt-kneaded in a twin-screw kneader, cooled and solidified, and then roughly pulverized with a hammer mill . In a counter jet mill type pulverizing / classifying machine having at least a pulverizing jet nozzle, a classifying rotor, and an inner cylinder, which are arranged to face each other, compressed air pressure supplied to the pulverizing nozzle: 0.5 Mpa, classifying rotor peripheral speed: 40 m / s, flow As a result of pulverization under conditions of in-layer pressure: −5 kpa, weight average particle size: 6.5 μm, 4 μm or less Fine powder content (number average): 58 pop. %, 16 μm or more coarse powder content (weight average): 1.2 wt. % Toner could be obtained with a production capacity of 13 kg / h. A multisizer manufactured by Coulter Counter was used for the particle size measurement.
[0015]
Comparative Example 1
Using the same kneaded product and pulverization classification conditions as in Example 1, pulverization was performed by the conventional counter jet mill type pulverization classification shown in FIG. 6. As a result, the weight average particle size: 6.5 μm, 4 μm or less Fine powder content (Number average): 61 pop. %, 16 μm or more coarse powder content (weight average): 1.2 wt. % Toner could be obtained with a production capacity of 10 kg / h.
[0016]
Reference example 2
Using the same kneaded product and pulverization classification conditions as in Reference Example 1 , the inner cylinder length H2 shown in FIG. 2 is set to the height H1 between the classification rotor center line CD and the pulverization nozzle center line AB. As a result of grinding with a counter jet mill type grinding classifier equipped with H2 = 1 / 2H1, weight average particle size: 6.5 μm, 4 μm or less Fine powder content (number average): 59 pop. %, 16 μm or more coarse powder content (weight average): 1.2 wt. % Toner could be obtained with a production capacity of 12 kg / h.
[0017]
Reference example 3
Using the same kneaded product and pulverization classification conditions as in Reference Example 1 , pulverization was performed with a counter jet mill pulverization classifier equipped with a distance H3 between the lower part of the inner cylinder and the pulverization nozzle center line AB shown in FIG. As a result, weight average particle diameter: 6.5 μm, 4 μm or less Fine powder content (number average): 59 pop. %, 16 μm or more coarse powder content (weight average): 1.2 wt. % Toner could be obtained with a production capacity of 13 kg / h.
[0018]
Reference example 4
Using the same kneaded product and pulverization classification conditions as in Reference Example 1 , the inner cylinder diameter H5 shown in FIG. 2 was pulverized by a counter jet mill type pulverization classifier in which H5 = 1 / 2H4 with respect to the pulverizer body inner diameter H4. Results, weight average particle size: 6.5 μm, 4 μm or less Fine powder content (number average): 58 pop. %, 16 μm or more coarse powder content (weight average): 1.2 wt. % Toner could be obtained with a production capacity of 13 kg / h.
[0019]
Example 5
Using the same kneaded product and pulverization classification conditions as in Example 1, pulverization was carried out with a counter jet mill type pulverization classifier equipped with a shielding plate shown in FIG. 3. As a result, weight average particle size: 6.5 μm, containing 4 μm or less fine powder Rate (number average): 57 pop. %, 16 μm or more coarse powder content (weight average): 0.8 wt. % Toner could be obtained with a production capacity of 14 kg / h.
[0020]
Example 6
Using the same kneaded product and pulverization classification conditions as in Example 1, pulverization was performed with a counter jet mill type pulverization classifier in which the shielding plate width H6 shown in FIG. 4 was set to H6 = 1 / 2H7 with respect to the diameter H7 of the classification rotor. Results, weight average particle diameter: 6.5 μm, 4 μm or less Fine powder content (number average): 57 pop. %, 16 μm or more coarse powder content (weight average): 0.9 wt. % Toner could be obtained with a production capacity of 14 kg / h.
[0021]
Example 7
Using the same kneaded product and pulverization classification conditions as in Example 1, a counter-jet mill type pulverization in which the lower limit of the classification rotor and the distance H8 between the shielding plates shown in FIG. 4 are set to H8 = 1 / 2H7 with respect to the diameter H7 of the classification rotor. As a result of grinding with a classifier, the weight average particle size: 6.5 μm, 4 μm or less Fine powder content (number average): 57 pop. %, 16 μm or more coarse powder content (weight average): 0.8 wt. % Toner could be obtained with a production capacity of 15 kg / h.
[0022]
Example 8
Using the same kneaded product and pulverization classification conditions as in Example 1, the inner cylinder shown in FIG. 5 was pulverized by a counter jet mill type pulverization classifier held by a shielding plate, and the weight average particle size: 6.5 μm, 4 μm Fine powder content (number average): 57 pop. %, 16 μm or more coarse powder content (weight average): 0.8 wt. % Toner could be obtained with a production capacity of 15 kg / h.
[0023]
【The invention's effect】
The counter jet mill type pulverizing and classifying machine of the present invention allows the pulverized material to reach the classification part more accurately and can be efficiently subjected to the classification process. We were able to provide a counter jet mill type pulverization classifier that could be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a counter jet mill type pulverizing and classifying machine of the present invention.
FIG. 2 is a cross-sectional view of a counter jet mill type pulverizing and classifying machine, explaining H1, H2 and H3 which are constituent requirements of the counter jet mill type pulverizing and classifying machine of the present invention.
FIG. 3 is a cross-sectional view of a counter jet mill type pulverizing / classifying machine provided with a shielding plate of the present invention.
FIG. 4 is a cross-sectional view illustrating H6 and H7, which are constituent requirements of the counter jet mill type pulverizing and classifying machine of the present invention.
FIG. 5 is a cross-sectional view illustrating a correspondence relationship between a shielding plate and a rotor of a classification rotor, which is a constituent requirement of the counter jet mill type pulverization classifier of the present invention.
FIG. 6 is a cross-sectional view of a conventional counter jet mill type pulverization classification without an inner cylinder.
[Explanation of symbols]
H1 Height between classification rotor center line CD and grinding nozzle center line AB H2 Inner cylinder length H3 Distance between lower part of inner cylinder and grinding nozzle center line AB H4 Inner diameter of grinding machine main body H5 Inner cylinder diameter H6 Shield plate width H7 Classification rotor diameter H8 Distance between lower limit of classification rotor and shield plate

Claims (4)

The pulverization chamber is configured to have at least a pulverization jet nozzle installed facing the lower part of the pulverization chamber, an inner cylinder installed at the upper part of the jet nozzle, and a classification rotor installed at the upper part of the inner cylinder. A counter jet mill type pulverizing and classifying machine, wherein a shielding plate is installed below the classification rotor and above the inner cylinder. 2. The counter jet mill type pulverizing / classifying machine according to claim 1, wherein the diameter H5 of the inner cylinder and the inner diameter H4 of the pulverizing machine main body satisfy the requirements of the following formula.
1 / 3H4 ≦ H5 ≦ 2 / 3H4 3. The counter according to claim 1, wherein a distance H <b> 3 between the lower portion of the inner cylinder and the center line A-B of the inner cylinder satisfies the following formula. Jet mill type pulverizer.
50mm ≦ H3 ≦ 150mm The counter jet mill type pulverizing / classifying machine according to any one of claims 1 to 3, wherein the shielding plate also serves as a holder for installing the inner cylinder.

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