JPH0326349A - Grinding method for powder - Google Patents

Abstract

PURPOSE:To desirably enhance the grinding and treating capacity by specifying the apex angle of the tip part in the collision face of a collision member and also regulating the spreading angle of an acceleration pipe to a specified region. CONSTITUTION:When a powdery raw material is supplied from a charging port 1, it is accelerated by compressed air blown out through a nozzle 2 and discharged into a grinding chamber 8 from the outlet 13 of an acceleration pipe and furthermore struck on a collision face 14. The ground powdery raw material is smoothly carried to a classifier 24 from a discharge port 5. Fine powder is removed as classified powder and coarse powder is charged together with the powdery raw material form the charging port 1 again. The collision faces of respective collision members 4 are formed into an oblique conical shape which has a constant apex angle phi not smaller than 110 deg. and smaller than 180 deg.. Thereby the collided powdery raw material is dispersed to the whole circumferential direction and allowed to secondarily collide against the opposite grinding wall and thereby grinding capacity is enhanced.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a method for pulverizing powder raw materials with an impact-type air-flow pulverizer using a jet stream (high-pressure gas). The present invention relates to a powder pulverization method for efficiently producing toner or colored resin powder for toner used in a forming method.

[Prior Art] A collision-type air current pulverizer using a jet stream conveys a powder raw material by a jet stream, collides the powder raw material with a collision member, and crushes it by the impact force.

Conventionally, the collision surface l4 of the collision member in such a crusher is
As shown in Figures 6 and 7, a flat type that is perpendicular or inclined (for example, 45 degrees) to the direction of the jet stream carrying the powder raw material (the axial direction of the accelerator tube) has been used. (JP-A-57-50554 and JP-A-58-
(See Publication No. 143853).

In the crusher shown in Figure 6, the powdered raw material with a coarse thread diameter is
The powder raw material is supplied to the accelerating tube 3 from above the input port, and is struck by the jet air stream blown out from the jet nozzle 2 against the collision surface 14 of the collision member 4, is crushed by the impact force, and is discharged from the discharge port 5 to the outside of the crushing chamber. be discharged. However, when the collision surface l4 is perpendicular to the axial direction of the acceleration tube 3, the raw material powder blown out from the jet nozzle 2 and the collision surface 14
There is a high proportion of the powder reflected by the collision surface 14 coexisting in the vicinity of the collision surface 14, and as a result, the powder concentration near the collision surface 14 becomes high, resulting in poor pulverization efficiency. Furthermore, the primary collision is mainly at the collision surface 14, and it cannot be said that the secondary collision with the crushing chamber wall 6 is effectively utilized. Furthermore, in a crusher where the angle of the collision surface is perpendicular to the acceleration tube 3, when crushing a material whose powder raw material is a thermoplastic resin, fusion and agglomerates are likely to occur due to local heat generation at the time of collision. Stable operation of the equipment becomes difficult6. Therefore, even if you try to improve the crushing impact force, 6. It becomes impossible to use highly compressed gas of 5 kg/cm2 or more.

Incidentally, toner or colored resin powder for toner used in an electrophotographic image forming method usually contains at least a binder resin and a colorant or magnetic powder. Such toner develops an electrostatic charge image formed on a latent image carrier, and the formed toner image is transferred to a transfer material such as plain paper or plastic film, and is then transferred to a transfer material such as a heat fixing means, a pressure roller fixing means, or a heat pressure roller fixing means. The toner image on the transfer material is fixed to the transfer material by a fixing device such as a roller fixing means.

Therefore, the binder resin used in the toner has the property of being plastically deformed when heat and/or pressure is applied. Currently, toner or colored resin powder for toner is produced by melt-kneading a mixture containing at least a binder resin and a colorant or magnetic powder (further containing a third component if necessary), cooling the molten mixture, and then cooling it. It is prepared by crushing a substance and classifying the crushed substance. The pulverization of cooled materials usually involves coarse pulverization (or medium pulverization) using a mechanical impact pulverizer, and then the coarse powder obtained by this pulverization is finely pulverized using an impact type airflow pulverizer that uses a jet stream. do. However, it has been difficult to increase the concentration of the material to be pulverized and to perform pulverization using highly compressed gas of 7.0 kg/cm2 or more.

In the crusher shown in FIG. 7, since the collision surface l4 is inclined with respect to the axial direction of the acceleration tube 3, the powder concentration near the collision surface l4 is lower than that in the crusher shown in FIG. The crushing pressure is dispersed and reduced. Furthermore, it cannot be said that the secondary collision with the crushing chamber wall 6 is effectively utilized.

As shown in FIGS. 7 and 8, when the collision surface 14 is inclined at an angle of 45 degrees with respect to the acceleration tube, the above-mentioned problems occur less when crushing thermoplastic resin. however,
Since the impact force used for pulverization during collision is small, and there is less pulverization due to secondary collision with the pulverizing chamber wall 6, the crusher is 1/2 to 1/1 as large as the pulverizer shown in FIG. The crushing ability drops to 5.

Therefore, the pulverization efficiency is good when pulverizing raw materials to be pulverized, especially materials containing thermoplastic resins, and 6. 5kg/
There is a long-awaited pulverization method that can improve the pulverization ability even when using highly compressed gas of 1.5 cm or more.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems, and furthermore, in the conventional example, since the accelerator tube has a narrow divergence angle θ of 6.5° or less, it is possible to increase the high-pressure gas flow rate. It is an object of the present invention to provide a pulverization method that eliminates the drawback that the desired pulverization processing capacity cannot be improved due to pressure loss occurring in the acceleration tube.

In other words, the present invention provides a method for pulverizing powder that can be pulverized using highly compressed gas (for example, 6.5 kg/cm" or more) without reducing the concentration of the material to be pulverized, even when pulverizing materials containing thermoplastic resin or the like. There is a particular thing.

Also, fusion during crushing. The object of the present invention is to provide a method for pulverizing powder that does not generate aggregates, coarse particles, etc. and enables stable operation of an apparatus.

[Means and effects for solving the problems] The present invention is characterized by an acceleration tube that conveys and accelerates powder using high-pressure gas, and a collision that uses impact force to crush the powder ejected from the acceleration tube. In pulverization using a collision type airflow pulverizer in which a member is provided in a pulverizer chamber facing the outlet of an accelerating tube, the apex angle of the tip portion of the collision surface of the collision member is 110° or more and 180°.
An oblique cone or an oblique conical shape with a diameter of less than 6 degrees is used, the expansion angle of the acceleration tube is set to 7 degrees or more and 9 degrees or less, and the pressure of the high-pressure gas is set to 6. There is a method for pulverizing powder to a particle size of 5 kg/cm2 or more.

The present invention also provides a method of pulverizing powder using a material containing a thermoplastic resin as a raw material for the powder.

That is, the present invention provides 6. It has an acceleration tube that conveys and accelerates the material to be crushed by high pressure gas of 5 kg/cm2 or more, and a mixed air flow of the high pressure gas and particles of the material to be crushed is injected from the outlet of the acceleration tube and is provided opposite to the outlet of the acceleration tube. In the collision type airflow crusher, which crushes the collision member by colliding with the collision surface of the collision member, by setting the expansion angle θ of the acceleration tube to 7° or more and 9° or less, acceleration can be achieved without reducing the speed of the airflow. The pressure loss within the pipe is reduced, and as shown in Figs. 6. Improving the pulverization capacity by dispersing the object to be crushed that collided with the collision surface in the circumferential direction and causing a secondary collision with the opposing crushing chamber wall; 6. It is possible to provide a pulverization method in which fusion of the thermoplastic resin material and the pulverized powder is suppressed even when high-pressure gas of 5 kg/cm2 or more is injected from the accelerator tube, and the generation of aggregates and coarse particles is small. This is what I did.

Hereinafter, the present invention will be explained based on the drawings.

1 to 5 are schematic diagrams showing one embodiment of the present invention. FIG. 2 is an enlarged view of the main part of FIG. 1, and the accelerating tube 3 in the figure is shown in FIGS. Similar to the conventional impingement type air flow crusher shown in the figure,
A high-pressure gas supply nozzle 2 is connected thereto, and a collision member 4 is provided opposite the outlet 13 of the acceleration tube 3. The acceleration tube 3 is
It is a monotonically expanding tube with an expansion angle θ of 7° or more and 9° or less.

Furthermore, if the spreading angle θ is in the range of 7.5° or more and 8.5° or less, it is optimal because it improves the pulverization processing capacity. Next, the operation of the above embodiment will be explained. In order to improve the pulverization processing capacity of an impingement type air flow pulverizer, it is effective to increase the flow rate of compressed gas that provides the impact force for pulverization and to increase the pressure of the gas flow. However, in the case of an accelerator tube with a non-vortex spread angle θ of 7°, such as in a conventional impingement type air flow crusher, pressure loss occurs within the accelerator tube, and the ability to increase the compressed gas flow rate and pressure is slightly reduced. Unable to improve crushing ability. On the other hand, in the case of an accelerating tube whose divergence angle θ exceeds 96, as the angle of the accelerating tube widens,
The cross-sectional area of the accelerating tube outlet 13 increases, and conversely, the speed of the particle mixture air flow injected from the accelerating tube decreases, so it is impossible to improve the pulverization ability to the extent that the pressure of the compressed gas increases. Can not. Therefore, an accelerating tube having a divergence angle θ of 7° or more and 9° or less, excluding the above-mentioned range, is most suitable for improving the pulverization processing capacity.

[Example] The present invention will be explained in detail below using Examples and Comparative Examples.

The powder was pulverized using an impact type air flow pulverizer shown in FIGS. 1 to 3 and 5 of the accompanying drawings.

A fixed wall type wind classifier was used as a classification means for classifying the pulverized powder into fine powder and coarse powder.

The collision type air flow crusher has a cylindrical collision member 4 made of aluminum oxide ceramic with a diameter (b) of 60 mm.
The tip of the collision member 4 has an apex angle (ψ)
Two types of oblique conical shapes having angles of 110° and 160° were used. The inner wall of the crushing chamber 8 was coated with ceramic. The inner diameter of the acceleration tube outlet 13 is 25 mm, and the acceleration tube outlet l3
The closest distance (a) from the collision surface 14 to the collision surface 14 is 60 mm, and the closest distance (c) between the collision member 4 and the crushing chamber wall 6 is 2.
It was 0 mm. The cross section of the impingement type air flow crusher along the plane AA' had a U-shape as shown in FIG. The distance between the collision member 4 and the left and right and lower crushing chamber walls 6 is from 20 to about 4
It was 0 mm.

Furthermore, the inner diameter (d1) of the high pressure gas supply nozzle is 11 mm.
The acceleration tube outlet 13 had an inner diameter (d2) of 29 mm, the overall length (L) of the acceleration tube 3 was 133 mm, and the acceleration tube had a divergence angle (θ) of 7.7°.

On the other hand, as the raw material 7, the following was used.

The toner raw material consisting of the mixture of the above formulation is melted and mixed at about 180°C for about 1.0 hours, then cooled and solidified to a temperature of 910, and the cooled mixture of the melted and mixed mixture is heated in a hammer mill to a temperature of 100 to 100.
The powder material was coarsely ground into particles of 00 μm and used as a powder raw material.

When the powder raw material is supplied from the input port 1 at a rate of 43 kg/Hr, compressed air (8.0 kg/Hr) is blown out from the nozzle 2.
kgf/cm2), the powder raw material is accelerated in the acceleration tube 3 and discharged from the acceleration tube outlet 13 into the crushing chamber 8, and the powder raw material 7 is struck against the collision surface 14 and crushed by the impact force. . At the same time, the colliding powder raw material was dispersed in the entire circumferential direction by the oblique cone-shaped collision surface l4 and secondly collided with the opposing crushing chamber wall 6, where it was further crushed.

The crushed powder raw material is smoothly transferred to the classifier 2 from the discharge port 5.
4, the fine powder was removed as classified powder, and the coarse powder was again input from the input port 1 together with the powder raw material. As a result, 44 pieces of crushed powder with a weight average particle size of 12 pm were used as fine powder.
Collected at the rate of kg/Hr.

In this way, the collision surface of each collision member 4 has a constant apex angle.
Since it has an oblique conical shape with (ψ), the colliding powder raw material is dispersed in the entire circumferential direction and causes a secondary collision with the opposing crushing wall. Therefore, it has been confirmed that fusion, agglomerates, and coarse particles do not occur near the collision member, and there is no increase in powder concentration, and furthermore, because of secondary collision, the crushing capacity is much higher than before.

The apex angle (ψ) of the same powder raw material as in Example 1 is shown in Fig. 4.
When pulverization was performed in the same manner as in Example 1 using a collision member having two types of oblique cone-shaped collision surfaces with inclinations of 110° and 160°, the dust concentration near the collision surface during pulverization was as follows. As in Example 1, it was confirmed that the crushing capacity was much higher than that of the conventional method because of the secondary collision without rising. The amount of powder raw material input was adjusted according to the amount to be processed.

The apex angle (ψ) 1 of the same powder raw material as in Example 1 shown in FIG.
When pulverization was performed in the same manner as in Example 1 using a collision member having an oblique cone-shaped collision surface with an inclination of 70°, the dust concentration near the collision surface during pulverization did not increase, and secondary collisions occurred. Therefore, it was confirmed that the crushing capacity was much higher than that of the conventional method.

A powder raw material similar to that in Example 1 was pulverized using a conventional impingement type air flow pulverizer shown in FIG. In this pulverizer, the material was pulverized in the same manner as in Example 1 using the collision member 4 having a planar collision surface 14 perpendicular to the acceleration tube 3.

In this collision type air flow crusher, the inner diameter (dI) of the high-pressure gas supply nozzle is 9 mm, and the inner diameter (d2) of the acceleration tube outlet l3 is 9 mm.
) is 24 mm, and the total length (L) of the accelerator tube 3 is 153 m.
m, the expansion angle (θ) of the acceleration tube is 5.6 degrees, and the compressed air blown out from the acceleration tube 3 is 6.
0 kgf/cm''. The powder material that collided with the collision surface l4 was reflected in the direction opposite to the discharge direction, so the powder concentration near the collision surface became extremely high. When the supply rate exceeds 100 kg/Hr, fusion, agglomerates, and coarse particles begin to occur on the collision member, and the fused substances sometimes clog the accelerator tube outlet 13 and the classifier. The amount had to be reduced to 10 kg per hour, which was the limit of the grinding capacity.

Comparative Example 1 A powder raw material similar to that of Example 1 was pulverized using a conventional impingement air flow pulverizer shown in FIG. In this pulverizer, the material was pulverized in the same manner as in Example 1 using the collision member 4 having a planar collision surface 14 perpendicular to the acceleration tube 3.

In this collision type air flow crusher, the inner diameter (d,) of the high-pressure gas supply nozzle is 11 mm, and the inner diameter (d,) of the acceleration tube outlet 13 is 11 mm.
2) is 24 mm, and the total length (L) of the accelerator tube 3 is 133 mm.
mm, the expansion angle (θ) of the accelerating tube is 5.6°, and the compressed air blown out from the accelerating tube 3 is 8.6 mm.
It was pulverized at 0 kgf/cm2. The powder raw material that collided with the collision surface l4 is reflected in the direction opposite to the discharge direction, so the powder concentration near the collision surface becomes significantly high.Furthermore, the impact force becomes large, so that it fuses on the collision member. , aggregate,
Coarse particles began to form, and the fused materials clogged the accelerator tube outlet 13 and the classifier, making it impossible to achieve the pulverizing function.

Comparative Plate 13 1 4 The same powder raw material as in Example 1 was pulverized using a conventional impingement type air flow pulverizer shown in FIG. In the crusher, the material was crushed in the same manner as in Example 1 using the collision member 4 having a planar collision surface 14 perpendicular to the acceleration tube 3.

In this collision type air flow crusher, the inner diameter (d1) of the high-pressure gas supply nozzle is 9 mm, and the inner diameter (d2) of the acceleration tube outlet 13 is 9 mm.
) is 24 mm, and the total length of the accelerator tube 3 (Ll is 1531
IllI1, and the expansion angle (θ) of the accelerator tube is 5.6
The compressed air blown out from the acceleration tube 3 has a shape of 8. The powder raw material that collided with the collision surface l4 is reflected in the direction opposite to the discharge direction, so the powder concentration near the collision surface becomes extremely high, and furthermore, the impact force is large. fused on the collision member due to
Agglomerates and coarse particles begin to form, and fused materials reach the acceleration tube outlet 13.
It clogged the machine and classifier, making it unable to perform its pulverizing function.

L powder 1 A powder raw material similar to that in Example 1 was pulverized using a conventional impingement type air flow pulverizer shown in FIGS. 7 and 8.

When pulverization was performed in the same manner as in Comparative Example 2 using a collision member having a collision surface of 45° in the crusher, the powder raw material that collided with the collision surface moved in the direction away from the acceleration tube outlet l3 compared to Comparative Example 2. Since it was reflected, no fusion or agglomeration occurred. However, since the impact force becomes weak during the collision, the pulverization efficiency is poor, and only about 9 kg of fine powder with a weight average particle size of 12 pm can be obtained per hour.

The results of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table I below.

(Margin below) l5 1 6 Real W The following materials were used as raw materials.

A toner raw material consisting of a mixture of the above formulation is melted and mixed at about 180°C for about 1.0 hours, cooled and solidified, and the solid material is coarsely ground into particles of 100 to 1000 #Lm using a hammer mill as a powder raw material. And so.

14. Powder raw material from input port 1. 5 kg/Hr, compressed air of 8.0 kgf/cm" was introduced from nozzle 2, and the inner diameter (d1) of the high pressure gas supply nozzle was 1 1
mm, and the inner diameter (d2) of the acceleration tube outlet l3 is 29 mm.
, total length (L) is 133mm 1 spread angle (θ)
is 7. r-shaped accelerator tube and apex angle (ψ) 1l shown in Fig. 3
Figures 1 and 2 are equipped with collision members having two types of oblique cone-shaped collision surfaces with inclinations of 0° and 160°.
Note 1: The processing capacity of the pulverizer of Comparative Example 1 was set to 1.

The powder was pulverized using a collision type air flow pulverizer 18, and the pulverized powder was classified into fine powder and coarse powder using a classifier 24. Fine powder with a weight average particle size of 12 ILm was collected at a rate of 15.8 kg per hour.

The same powder raw material as in Example 4 was prepared at the apex angle (ψ
) Grinding was performed in the same manner as in Example 4 using the collision type air flow mill shown in Fig. 1, which was equipped with a collision member having two types of oblique cone-shaped collision surfaces with inclinations of 110° and 160°, respectively. , fine powder with a weight average particle size of about 12 pm per hour
They were collected at a rate of 5.8 kg.

The amount of powder raw material input was adjusted depending on the amount to be processed.

The same powder raw material as in Example 4 was prepared at the apex angle (ψ
) When pulverization was performed in the same manner as in Example 4 using the impingement type air flow pulverizer shown in FIG. 12pm fine powder per hour. Collected at the rate of 7Kg.

When the same powder raw material as in Example 4 was pulverized in the same manner as in Comparative Example 1 using the impingement air flow pulverizer shown in Fig. 6, a fine powder with a weight average particle size of about 12 pm was produced per hour. Only 7 kg was collected.

Comparison 1 When the same powder raw material as in Example 4 was pulverized in the same manner as in Comparative Example 2 using the collision type air flow pulverizer shown in FIG.
The powdered material that collides with the powder is reflected in the direction opposite to the discharge direction, so the powder concentration near the collision surface becomes significantly high.
Furthermore, as the impact force became larger, fusion occurred on the collision member.
Agglomerates and coarse particles begin to form, and fused materials reach the acceleration tube outlet 13.
It clogged the classifier and made it impossible to achieve the crushing function.

Ratio (l) When the same powder raw material as in Example 4 was pulverized in the same manner as in Comparative Example 3 using the collision type air flow pulverizer shown in FIG.
The powder raw material collided with the collided member is reflected in the direction opposite to the discharge direction, so the concentration of powder 1920 near the collided surface becomes significantly high, and the impact force increases, causing fusion on the collided member. , aggregates, and coarse particles began to form, and the fused materials clogged the accelerating tube outlet 13 and the classifier, making it impossible to achieve the pulverizing function.

Ratio 10 When the same powder raw material as in Example 4 was pulverized in the same manner as in Comparative Example 4 using the collision type air flow pulverizer shown in FIGS. 7 and 8, fine powder with a weight average particle size of about 12 pm was 6kg L per hour,
or not collected.

The results of Examples 4 to 6 and Comparative Examples 5 to 8 are summarized in the second section below.
Shown in the table.

(Margin below) 2l -Note 1: The processing capacity of the crusher in Comparative Example 5 was set to 1.

22 [Effect of the invention] As explained above, when the divergence angle θ of the accelerator tube is set to 7° or more, 9
'' or less, and the apex angle of the tip of the collision plate surface is 110
By forming the powder raw material containing a thermoplastic resin into an oblique conical shape or an oblique conical shape with an angle of at least 180°, 6. 5kg
Even if a highly compressed gas of 1/cm" or more is injected, no fusion, agglomerates, or coarse particles are generated during pulverization, allowing stable operation of the equipment.Furthermore, the equipment can be operated stably without increasing the size of the equipment.
The conventional crushing capacity can be significantly improved.

[Brief explanation of drawings]

1 and 2 are diagrams schematically showing the cross section and the crushing/classifying process of the collision type air flow crusher used in the present invention, in which the collision member has an oblique conical shape or a conical conical shape, and FIG. 4 and 4 are diagrams showing the oblique conical shape and the tip of the oblique conical collision member used in the present invention. FIG. 5 is a diagram schematically showing a cross section of the crusher shown in FIG. 1 taken along the line AA'. FIG. 6 is a diagram schematically showing a cross section and a crushing/classifying process of a collision type air flow crusher as a comparative example in which the collision surface of the collision member is perpendicular to the axial direction of the accelerator tube. Figure 7 schematically shows the cross section and crushing/classifying process of a collision type airflow crusher as a comparative example, in which the collision surface of the collision member is inclined upward at 45 degrees with respect to the axial direction of the accelerator tube. FIG. 8 is a diagram showing the B-
It is a figure which schematically showed the cross section in B' plane. l...Powder raw material input port 2...Compressed gas supply nozzle 3...Acceleration tube 4...Collision member 5...Outlet port 6...Crushing chamber wall 7...Powder raw material 8 ...Crushing chamber l3...Acceleration tube outlet 14...Collision surface 23 2 4 24...Classifier ψ...Collision member apex angle θ...Acceleration tube expansion angle d,...High pressure gas Supply nozzle inner diameter d2...Acceleration tube outlet inner diameter L...Acceleration tube total length

Claims (2)

[Claims] (1) Collision type consisting of an acceleration tube that conveys and accelerates powder using high-pressure gas, and a collision member that crushes the powder ejected from the acceleration tube by impact force in the crushing chamber opposite the acceleration tube outlet. In the pulverization using an air flow pulverizer, the colliding member has an oblique conical or oblique conical shape with an apex angle of 110° or more and less than 180° at the tip of the colliding surface, and the accelerator tube has a spreading angle of 7°. A method for pulverizing powder, characterized in that the pulverization is carried out at a pressure of 6.5 kg/cm^2 or more, with the angle being 9° or less. (2) The method for pulverizing powder according to claim 1, characterized in that a material containing a thermoplastic resin is used as a raw material for the powder.