JPH0330845A - Method for pulverizing powder - Google Patents

Abstract

PURPOSE:To improve the pulverizing capacity of a pulverizer by forming a collision face of collision member into a shape which has a specified angle with a direction of acceleration tube and by making a divergent angle of the acceleration tube a specified angle. CONSTITUTION:A raw material of powder supplied through a charge port 1 is accelerated by compressed air ejected from a nozzle 2 and blown out of the outlet 13 of an acceleration tube into a pulverizing chamber 8, wherein the raw material 7 is thrown onto a collision face 14, pulverized by an impulse force, dispersed all around the periphery by the collision face 14 which has an angle of 55 deg. or larger and smaller than 90 deg. with the direction of acceleration tube, made to collide secondarily with the wall 6 of the pulverizing chamber and further pulverized there. The pulverized raw material of powder is carried out of a discharge port 5 to a classifier 24, fine powder is removed as a classified powder and coarse powder is thrown into the charge port 1 together with the law material so as to be processed once again. It is possible to improve a capacity of pulverizer by this method.

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, as shown in FIGS. 7 and 8, the collision surface 14 of the collision member in such crushing and pounding is perpendicular or inclined (for example, 45°) have been used (Japanese Unexamined Patent Publications No. 57-50554 and No. 58)
(Refer to Publication No.-143853).

In the crusher of Fig. 7, the powder raw material having a coarse particle size is
The powder raw material is supplied to the accelerator tube 3 from the input port 1, 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, and is crushed by the impact force, and is discharged from the discharge port 5 to the outside of the crushing chamber. is discharged. However, when the collision surface 14 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 near the collision surface 14, and as a result, the powder concentration near the collision surface 14 is high, resulting in poor pulverization efficiency.Furthermore, the primary The collision is the main one, and the secondary collision with the crushing chamber wall 6 cannot be said to be effectively utilized.Furthermore, in a crusher where the angle of the collision surface is perpendicular to the acceleration tube 3, the powder raw material is heated. When crushing materials that are plastic resins, fusion and agglomerates are likely to occur due to local heat generation during collision, making stable operation of the equipment difficult. It is no longer possible to use highly compressed gas of .5 kg/cm'' 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 the electrostatic charge image formed on the 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 and pressure application. 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, toners or colored resin powders for toners are produced by melt-kneading a mixture containing a small amount of a binder resin and a colorant or magnetic powder (if necessary, further containing a third component), and then cooling the molten mixture. It is prepared by pulverizing the cooled material and classifying the pulverized material.Usually, the pulverization of the cooled material is performed through a process of coarse (or medium) pulverization using a mechanical impact pulverizer. The resulting coarse powder is finely pulverized using a collision-type airflow pulverizer using a jet stream.
Therefore, it was difficult to pulverize the powder using highly compressed gas of 6.5 kg/cm2 or more.

In the crusher shown in FIG. 8, since the collision surface 14 is inclined with respect to the axial direction of the acceleration tube 3, the powder concentration near the collision surface 14 is lower (lower) than in the crusher shown in FIG. However, the crushing pressure is dispersed and lowered.Furthermore, it cannot be said that the secondary collision with the crushing chamber wall 6 is effectively utilized.

As shown in FIGS. 8 and 9, when the angle of the collision surface 14 is inclined at 45 degrees with respect to the acceleration tube, the above-mentioned problems occur less when crushing thermoplastic resin. however,
The impact force used for crushing during collision is small, and there is less crushing due to secondary collision with the crushing chamber wall 6, so the crushing is 1/2 to 1/1.5 compared to the crusher shown in Fig. 7. ability decreases.

Therefore, the pulverization efficiency is good when pulverizing raw materials to be pulverized, especially materials containing thermoplastic resins, and the
There is a long-awaited pulverization method that can improve the pulverization ability even when using a highly compressed gas of 10 m or more.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above problems, and furthermore, in the conventional example, the expansion angle θ of the accelerating tube is 6.5 degrees or less, which is narrow, so the flow rate of high-pressure gas is increased. In this case, pressure loss occurs in the accelerating tube, and the desired improvement in pulverization processing capacity cannot be achieved. The object of the present invention is to provide a pulverization method that eliminates such drawbacks.

In other words, we provide 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. It's about doing.

Another object of the present invention is to provide a method for pulverizing powder that does not generate fusion, agglomerates, coarse particles, etc. during pulverization and enables stable operation of the 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 collision surface of the colliding member is 55° or more and 90° with respect to the direction of the accelerating tube.
A straight pyramid, a right pyramid, or an oblique pyramid having an inclination 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 of pulverizing powder to 5 kg/cm''.

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 has an acceleration tube that conveys and accelerates the material to be crushed by high-pressure gas of 6.5 kg/cm or more, and a mixed air flow of the high-pressure gas and particles of the material to be crushed that is injected from the outlet of the acceleration tube. , in a collision type air flow crusher configured to collide with the collision surface of a collision member provided opposite the outlet of the acceleration tube to crush the particles, by setting the expansion angle θ of the acceleration tube to 7 degrees or more and 9 degrees or less, In order to avoid reducing the velocity of the airflow (and reduce the pressure loss within the accelerating tube, as shown in Figures 1 to 5, the collision surface should be tilted at an angle of 55° or more and less than 90° with respect to the accelerating tube. By providing a collision member having a collision surface in the shape of a right pyramid, a right pyramid, or an oblique pyramid, the material to be crushed that collides with the collision surface is dispersed in the entire circumferential direction, thereby preventing secondary collision with the opposing crushing chamber wall. This improves the pulverization processing capacity, and even if high-pressure gas of 6.5 kg/cm or more is injected from the accelerator tube, the fusion of the thermoplastic resin material and the pulverized powder is suppressed, and no aggregates are formed. This also makes it possible to provide a pulverization method that generates fewer coarse particles.

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

1 to 6 are schematic diagrams showing one embodiment of the present invention, and FIG. 2 is an enlarged view of the main part of FIG. Similar to the conventional example of collision-type gas pulverization shown in the figure, a high-pressure gas supply nozzle 2 is connected, and an acceleration pipe 3
A collision member 4 is provided opposite the outlet 13 of the engine. The accelerator tube 3 is a monotonically expanding tube with an expansion angle θ of 7 degrees or more and 9 degrees or less. Furthermore, if the spreading angle θ is in the range of 7.5 degrees or more and 8.5 degrees 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 spread angle θ of 7°, as in a conventional collision type airflow crusher, a pressure loss occurs in 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 accelerator tube whose expansion angle θ exceeds 9 degrees, as the angle of the acceleration tube expands,
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 degrees or more and 9 degrees 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.

Example 1 Example 2 Powder was pulverized using an impact type air flow pulverizer shown in FIGS. 1, 2, 3, and 6 of the attached 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 prismatic collision member 4 made of aluminum oxide ceramic having a dimension (b) of 60 mm.
The tip of the collision member 4 is at a distance of 55 mm with respect to the acceleration tube.
Two types of right pyramid shapes were used, one with an inclination of 80° and the other with an inclination of 80°. The inner wall of the crushing chamber 8 was coated with ceramic. The inner diameter of the acceleration tube outlet 13 was 25 mm, and the central axis of the acceleration tube 3 and the tip of the collision member 4 coincided. Accelerator tube outlet 13
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 0m+++. The cross section of the impingement type air flow crusher along the plane AA' was 1' shown in FIG. 6, and had a U-shape.

The distance between the collision member 4 and the left and right and lower crushing chamber walls 6 is 2.
It was 0 to about 40 mm.

Furthermore, the inner diameter (dl) 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 accelerating tube had a divergence angle (θ) of 7.7°.

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

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, then cooled and solidified, and the cooled mixture is coarsely ground into particles of 100 to 1000 gm using a hammer mill. It was used as a body 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.
gf/cm"), the powder raw material is accelerated in the acceleration tube 3 and discharged from the acceleration tube outlet 13 into the crushing chamber 8. The powder raw material 7 is struck against the collision surface 14 and is crushed by the impact force. At the same time, the colliding powder raw material is dispersed in the entire circumferential direction by each of the collision surfaces 14 in the shape of a right pyramid inclined at the above-mentioned angle, and causes a secondary collision with the opposing crushing chamber wall 6.
There it was further shattered.

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 kg of pulverized powder with a weight average particle size of 12 pm was obtained as fine powder.
Collected at a rate of g/Hr.

In this way, since the collision surface of each collision member 4 has a right pyramidal shape with an inclination of 55° and 80° with respect to the acceleration tube, the collided powder raw material is dispersed in the entire circumferential direction. death,
There was a secondary collision with the opposing crushing wall.

As a result, there is no fusion, agglomerates, or coarse particles near the collision member, and no increase in powder concentration (furthermore, due to secondary collisions, it has been confirmed that the crushing capacity is much higher than before. .

The same powder raw material as in Example 1 was used as shown in FIG. 4 using a collision member having two types of right pyramidal collision surfaces inclined at 55° and 80° with respect to the accelerator tube. When pulverization was performed in the same manner as in Example 1, the dust concentration near the collision member during pulverization did not increase and secondary collisions occurred, so as in Example 1, it was confirmed that the pulverization capacity was much higher than before. The amount of powder raw material input was adjusted according to the amount to be processed.

The same powder raw material as in Example 1 was used as shown in FIG. When pulverization was performed in the same manner as in Example 1, it was confirmed that the dust concentration near the collision surface during pulverization did not increase, and because of secondary collisions, the pulverization ability was much higher than before.

A powder raw material similar to that in 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 (dl) of the high-pressure gas supply nozzle is 9 mm, and the inner diameter (dl) of the acceleration tube outlet 13 is 9 mm.
) is 2411101, and the total length (L) of the accelerator tube 3 is 1
53mm, and the expansion angle (θ) of the accelerator tube is 5.6°.
The compressed air blown out from the acceleration tube 3 has the shape of
6.0 kgf/cm''.The powder raw material that collided with the collision surface 14 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 of body raw materials exceeds 10 kg/Hr, fusion, aggregates, and coarse particles begin to occur on the collision member.
There were cases where the fused material clogged the accelerator tube outlet 13 and the classifier. Therefore, it was necessary to reduce the pulverization throughput to 100 kg per hour, which became the limit of the pulverization capacity.

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 (dl) of the high-pressure gas supply nozzle is 11 mm, and the inner diameter (dl) of the acceleration tube outlet 13 is 11 mm.
2) is 24+nm, and the total length (L) of the accelerator tube 3 is 13
3 mm, and the expansion angle (θ) of the accelerating tube is 5.6°, and the compressed air blown out from the accelerating tube 3 is 8 mm.
, 0 kgf/cm''.The powder raw material that collided with the collision surface 14 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 Thick (because of this, fusion, agglomerates,
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.

L Comparison 51 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 (dl) of the high-pressure gas supply nozzle is 9 mm, and the inner diameter (dl) of the acceleration tube outlet 13 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°, and the compressed air blown out from the acceleration tube 3 is 8.0°.
It was pulverized at kgf/cm2. The powder raw material that collided with the collision surface 14 is reflected in the direction opposite to the discharge direction, so the powder concentration near the collision surface becomes extremely high (furthermore, because the impact force becomes large, it melts on the collision member). Agglomerates, aggregates, and coarse particles began to form, and the fused substances clogged the accelerating tube outlet 13 and the classifier, making it impossible to achieve the pulverizing function.

Miku IL The same powder raw material as in Example 1 was pulverized using the collision type air flow pulverizer shown in FIGS. 8 and 9. When pulverization was performed in the same manner as in Comparative Example 2 using a collision member having a 45-degree collision surface in the pulverizer, the powder raw material that collided with the collision surface moved in a direction away from the acceleration tube outlet 13 compared to Comparative Example 2. No fusion or agglomeration occurred because the light was reflected to 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 pa+ can be obtained per hour.

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

Real JJ vomit 1 The following materials were used as powder raw materials.

A toner raw material consisting of a mixture of the above formulation was melted and mixed at about 180°C for about 1.0 hours, then cooled and solidified, and the solid was coarsely ground into particles of 100 to 1100 Jt using a hammer mill, which was used as a powder raw material. .

Powder raw material is supplied from the input port 1 at a rate of 15.8 kg/Hr, compressed air of 8.0 kgf/cm2 is introduced from the nozzle 2, and the inner diameter (dl) of the high-pressure gas supply nozzle is 11 m.
m, the inner diameter (d, ) of the acceleration tube outlet 13 is 29 mm, the total length (L) is 133 mm, and the expansion angle (θ) is 7.7°, and the acceleration tube shown in FIG. Fig. 1 and Note 1 The throughput of the crusher of Comparative Example 1 was 1. And so.

The powder was pulverized using each collision type air flow pulverizer shown in FIG. 2, and the pulverized powder was classified into fine powder and coarse powder using a classifier 24. As a result, as a fine powder, both had a weight average particle size of 12ILITl.
of powder was collected at a rate of 14.5 Kg per hour.

Powder raw material similar to that in Example 4 was used with respect to the acceleration tube shown in Fig. 4, which had two types of right pyramid-shaped collision surfaces with inclinations of (ψ) 55° and 80°. When pulverization was carried out in the same manner as in Example 4 using each of the collision type air flow pulverizers shown in FIG. 1 equipped with collision members, fine powder with a weight average particle size of 12H
Collected at a rate of 15.8 Kg per hour. The amount of powder raw material input was adjusted depending on the amount to be processed.

11 ■ Balls The same powder raw material as in Example 4 was applied to the acceleration tube shown in Fig. 5 into collision members having two types of oblique pyramid-shaped collision surfaces with inclinations of (ψ) 55° and 80°. When pulverization was carried out in the same manner as in Example 4 using each of the collision type air flow pulverizers shown in FIG. 1 equipped with It was done.

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. 7, 7 kg of fine powder with a weight average particle size of 12 gm was produced per hour. only was collected.

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 powder material collided with the collision surface is reflected in the direction opposite to the discharge direction, so the powder concentration near the collision surface is extremely high (becomes
Furthermore, as the impact force became larger, fusion occurred on the collision member.
Agglomerates and coarse particles begin to form, and the fused materials reach the acceleration tube outlet 13.
It clogged the classifier and made it impossible to achieve the crushing function.

When the same powder raw material as in Example 4 was crushed in the same manner as in Comparative Example 3 using the collision type air flow crusher shown in FIG. 7, the collision surface 14
The powder material collided with the collision surface is reflected in the direction opposite to the discharge direction, so the powder concentration near the collision surface is extremely high (becomes
Furthermore, as the impact force became larger, fusion occurred on the collision member.
Agglomerates and coarse particles begin to form, and the fused materials reach the acceleration tube outlet 13.
It clogged the classifier and made it impossible to achieve the crushing function.

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. 8 and 9, fine powder with a weight average particle size of 12#Lm is 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) Note 1: The processing capacity of the pulverizer in Comparative Example 5 was set to 1.

[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 tip of the collision surface is in the shape of a right pyramid, a right pyramid, or an oblique pyramid with an inclination of 55 degrees or more and less than 90 degrees with respect to the acceleration tube, and contains thermoplastic resin. The powder raw material does not generate fusion, agglomerates, coarse particles, etc. during pulverization even when highly compressed gas of 6.5 kg/c+n'' or more is input, allowing stable operation of the equipment, and furthermore,
The conventional crushing capacity can be significantly improved without increasing the size of the equipment.

[Brief explanation of drawings]

FIGS. 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 the shape of a right pyramid, a right pyramid, or an oblique pyramid. 3, 4, and 5 are diagrams showing the tips of each of the collision members in the shape of a right pyramid, a right pyramid, and an oblique pyramid used in the present invention. FIG. 6 is a diagram schematically showing a cross section of the crusher shown in FIG. 1 along the plane AA'. FIG. 7 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. FIG. 8 schematically shows the cross section and crushing/classifying process of a collision type air flow 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. 9 is a diagram showing B of the collision type air flow crusher shown in Fig. 8.
It is a diagram schematically showing a cross section in the -B' plane. 1... Powder raw material input port 2... Compressed gas supply nozzle 3... Accelerator tube 4... Collision member 5... Outlet port 6... Grinding chamber wall 7... Powder raw material 8 ...Crushing chamber 13...Acceleration tube outlet 14...Collision surface 24...Classifier ψ...Angle θ between the collision surface and the acceleration tube direction...Acceleration tube expansion angle dl...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 pulverization using an air flow pulverizer, the collision surface of the collision member is in the shape of any one of a right pyramid, a right pyramid, and an oblique pyramid with an inclination of 55° or more and less than 90° with respect to the direction of the accelerating tube. , the expansion angle of the acceleration tube is 7° or more and 9° or less, and the pressure of the high-pressure gas is 6.5 kg/c.
A method for pulverizing powder, characterized by pulverizing it to m^2 or more. (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.