JPH0651129B2 - Collision type airflow crusher and crushing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a collision type air flow pulverizer and a pulverization method using a jet air flow (high pressure gas).

The present invention also relates to a collision type airflow crusher and a crushing method for efficiently generating a toner or a colored resin powder for a toner used in an image forming method by electrophotography.

[Prior Art] A collision-type air flow crusher using a jet airflow conveys a powder raw material by a jet airflow, collides the powder raw material with a collision member, and pulverizes the powder raw material by the impact force.

The details will be described below with reference to FIG.

A collision member 4 is provided so as to face the outlet 13 of the accelerating tube 3 to which the compressed gas supply nozzle 2 is connected, and the flow of the high-pressure gas supplied to the accelerating tube 3 causes the powder raw material to be connected to the middle of the accelerating tube 3. The powder raw material is sucked into the inside of the accelerating tube 3 through the mouth 1, and is injected together with the high-pressure gas to collide with the collision member 4,
It is crushed by the impact. When the powder raw material is used for pulverizing to a desired particle size, a classifier is placed between the powder raw material input port 1 and the discharge port 5 to form a closed circuit, and the powder raw material is loaded into the classifier. Then, the coarse powder is supplied from the powder raw material charging port 1, the powder is crushed, and the crushed product is returned to the classifier from the discharge port 5 to be classified again. It becomes a finely pulverized product of particle size.

However, in the above-mentioned conventional example, it is difficult to sufficiently disperse the powder raw material sucked and introduced into the accelerating pipe in the high-pressure air flow. Therefore, the powder flow ejected from the accelerating pipe outlet is a thin dust flow. It separates into streams.

Therefore, the powder flow that hits the opposing collision plates becomes a partial (local) flow, the efficiency is reduced, and the processing capacity is reduced. In addition, if the treatment capacity is increased in such a state, the dust concentration is further increased locally, so that the efficiency is further reduced, and particularly in the resin-containing material, a fusion product is generated on the collision plate surface, which is preferable. Absent.

In order to improve the efficiency of pulverizing particles inside the accelerating tube, a pulverizing tube provided with a high-pressure gas feed tube for ejecting secondary high-pressure gas in front of the accelerating tube outlet is proposed in Japanese Patent Publication No. 46-22778. ing. This is intended to promote collision inside the acceleration tube and is a useful means for a crusher that crushes only inside the acceleration tube. With a crusher it is not a useful method. This is because if the secondary high-pressure gas is introduced to accelerate the collision in the acceleration tube, the carrier air flow due to the high-pressure gas introduced from the compressed gas supply nozzle is obstructed, and the velocity of the powder flow ejected from the acceleration tube outlet decreases. Resulting in. Therefore, the impact force that collides with the collision member decreases, and the pulverization efficiency decreases, which is not preferable.

Therefore, a crusher and a crushing method with good crushing efficiency are desired.

On the other hand, a toner or a colored resin powder for a toner used in an image forming method by electrophotography usually contains at least a binder resin and a colorant or magnetic powder. The 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 a plastic film, and then heated fixing means, pressure roller fixing means or heating pressure roller. The toner image on the transfer material is fixed to the transfer material by a fixing device such as fixing means. Therefore, the binder resin used for the toner has a characteristic of being plastically deformed when heat and / or pressure is applied.

Currently, a toner or a colored resin powder for a toner is melt-kneaded with a mixture containing at least a binder resin and a colorant or a magnetic powder (and optionally a third component), and the melt-kneaded product is cooled and cooled. It is prepared by crushing the product and classifying the crushed product. Generally, the crushed product is roughly crushed (or medium crushed) by a mechanical impact crusher, and then the crushed coarse powder is finely crushed by a collision type air flow crusher using a jet stream. is there.

In such a case, in the conventional collision type air flow crusher and crushing method as shown in FIG. 4, if it is attempted to further improve the processing capacity, a fusion product is generated on the surface of the collision plate, and stable production cannot be performed. Therefore, there is a demand for an efficient collision type airflow pulverizer and a pulverization method that solve the above problems in order to more efficiently generate a toner or a colored resin powder for a toner used in an image forming method by electrophotography. .

[Problems to be Solved by the Invention] An object of the present invention is to provide an efficient collision type airflow crusher and a crushing method in which the above problems are solved.

An object of the present invention is to provide a collision type airflow crusher and a crushing method for efficiently crushing powder mainly composed of a thermoplastic resin.

Another object of the present invention is to provide a collision type airflow crusher capable of efficiently producing toner or colored resin particles for toner used in a copying machine and a printer having a heating and pressure roller fixing means.

An object of the present invention is to provide a collision type airflow crusher capable of efficiently pulverizing resin particles having an average particle size of 20 to 2000 μm to an average particle size of 3 to 15 μm.

SUMMARY OF THE INVENTION The present invention comprises an accelerating tube for accelerating the powder by high-pressure gas, a crushing chamber, and a collision member for crushing the powder ejected from the accelerating tube by a collision force. In a collision type airflow crusher in which the collision member is provided in the crushing chamber so as to face the accelerating pipe outlet, a powder raw material inlet is provided in the accelerating pipe, and a secondary material is provided between the powder raw material supply port and the accelerating pipe outlet. The present invention relates to a collision type air flow crusher having an air inlet.

The present invention relates to a pulverization method in which powder is accelerated and conveyed by a high-pressure gas in an accelerating tube, the powder is discharged from an accelerating tube outlet into a crushing chamber, and the powder collides against an opposing collision member to crush the powder. The present invention relates to a method for pulverizing powder, characterized in that secondary air is introduced into the powder.

The collision type airflow pulverizer of the present invention can efficiently pulverize powder, which is a raw material to be pulverized, to the order of several μm using a high-speed airflow.

In particular, the collision type airflow crusher of the present invention efficiently uses a powder of a thermoplastic resin or a powder containing a thermoplastic resin as a main component,
It is possible to pulverize to the order of several μm using a high-speed air stream.

The present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic cross-sectional view of an airflow type crusher of the present invention and a flowchart of a crushing method in which a crushing process using the crusher and a classifying process by a classifier are combined. The powder raw material 7 to be crushed is supplied to the acceleration tube 3 through the powder raw material charging port 1 provided in the acceleration tube 3. Compressed gas such as compressed air is introduced into the accelerating tube 3 from the compressed gas supply nozzle 2, and the powder raw material 7 supplied to the accelerating tube 3 is instantaneously accelerated to have a high speed. The powder raw material 7 discharged from the accelerating pipe outlet 13 into the crushing chamber 8 at high speed is
It collides with the collision surface 14 of the collision member 4 and is crushed.

In the present invention, in FIG.
The secondary air introducing port 10 is provided between the accelerating tube outlet 13 and the accelerating tube outlet 13, and the secondary air is introduced into the accelerating tube to disperse the powder in the accelerating tube and eject the powder more uniformly from the accelerating tube outlet. Then, the crushing efficiency can be improved as compared with the conventional case by efficiently colliding with the facing collision surface. The secondary air introduced loosens the agglomeration of the powder that moves at high speed in the acceleration tube,
It contributes to disperse the powder.

FIG. 2 shows an enlarged cross-sectional view of the acceleration tube, which will be described in more detail. As a result of extensive studies on the method of introducing the secondary air to be introduced, the following conclusion was reached.

That is, regarding the position of the secondary air introduction, the distance between the powder raw material inlet 1 and the accelerating pipe outlet 13 is x, and the distance between the powder raw material inlet 1 and the secondary air inlet 10 is shown in FIG. If y, then x and y are More preferably Good results were obtained when

Regarding the introduction angle of the secondary air inlet, ψ is 10 ° when the angle with respect to the axial direction of the acceleration tube is ψ (Fig. 2).
Good grinding results were obtained when the condition of ≦ ψ ≦ 80 °, more preferably 20 ° ≦ ψ ≦ 80 ° was satisfied.

Regarding the air volume of the secondary air introduced, the air volume of the carrier air flow by the high pressure gas introduced from the compressed gas supply nozzle 2 is aNm ³ / min, and the total air volume of the secondary air introduced from the secondary air inlet is bNm. ^{When 3} / min, a and b are More preferably Good results were obtained when pulverization was carried out under the conditions satisfying

The technical idea in the present invention is to put the powder raw material into the carrier air flow by the high pressure gas introduced from the compressed gas supply nozzle,
In a collision-type airflow crusher that ejects from the accelerating tube outlet and collides the powder against the opposing collision plate for pulverization, the idea that the dispersion state of the powder in the accelerating tube may affect the pulverization efficiency Is based on. That is, since the powder raw material supplied from the accelerating tube flows into the accelerating tube in an agglomerated state, the dispersion in the accelerating tube becomes insufficient, and therefore, when ejected from the accelerating tube outlet, the dust concentration varies,
It was thought that the collision plate surface could not be used effectively and the crushing efficiency would decrease. This phenomenon becomes more remarkable as the crushing amount increases.

Therefore, in order to solve this, we have considered the introduction of secondary air. The present invention has been accomplished based on the idea that the secondary air is introduced into the accelerating tube so as to disperse the raw material powder without disturbing the carrier air flow of the high-pressure gas. As the secondary air, either a highly compressed gas or a normal pressure gas may be used. It is very preferable to install an opening / closing device such as a valve on the secondary air inlet to control the amount of introduced air. The number of inlets to be attached at which position in the circumferential direction of the accelerating tube may be appropriately set depending on the raw material to be crushed, the target particle size, and the like. As an example, FIG. 3 shows a sectional view taken along the line AA ′ in the case where eight secondary air inlets are attached in the circumferential direction of the acceleration tube. In this case, the distribution of the secondary air from the eight locations may be appropriately set. Further, the cross section of the acceleration tube is not limited to the circular shape.

The inner diameter of the accelerating tube outlet 13 is usually 10 to 100 mm, preferably smaller than the diameter of the collision member 4.

The distance between the acceleration tube outlet 13 and the tip of the collision member 4 is preferably 0.3 to 3 times the diameter of the collision member 4. If it is less than 0.3 times, over-milling tends to occur, and if it exceeds 3 times,
Crushing efficiency tends to decrease.

The crushing chamber of the collision type airflow crusher according to the present invention has the first
The shape is not limited to the box shape shown in the figure. The collision surface of the collision member is not limited to be perpendicular to the axial direction of the accelerating tube as shown in FIG. 1, but the powder ejected from the accelerating tube outlet can be efficiently reflected to the crushing chamber wall. More preferably, the shape is such that the next collision occurs.

As described above, according to the device and method of the present invention,
Since the powder raw material is well dispersed in the accelerating tube, it efficiently collides with the collision plate surface, and the pulverization efficiency is improved. That is, compared with the conventional pulverizer, the processing capacity is improved, and the particle size of the obtained product can be made smaller with the same processing capacity.

Further, in the conventional example, since the powder collides with the collision plate in a state where the powder is agglomerated, a fused substance is likely to be generated particularly when powder mainly containing a thermoplastic resin is used as a raw material. On the other hand, according to the present invention, since the colliding plate collides with the colliding plate in a dispersed state, it is difficult to generate a fused substance.

Further, in the conventional example, since the powder is agglomerated, there is a problem that over-pulverization is likely to occur, and the resulting pulverized product has a wide particle size distribution. On the other hand, according to the present invention, it is possible to prevent excessive pulverization and obtain a pulverized product having a sharp particle size distribution.

Further, according to the present invention, by efficiently introducing the secondary air, the suction capacity of air at the raw material inlet is improved, and therefore, the conveying ability of the pulverized raw material in the accelerating pipe is improved and the pulverization processing amount is improved. It can be higher than before. The effect of the apparatus and method of the present invention becomes more remarkable as the particle size becomes smaller.

[Examples] The present invention will be described in detail below based on examples.

Example 1 The toner raw material comprising the mixture of the above formulation is heated and kneaded, cooled and solidified, and then coarsely pulverized into particles of 100 to 1000 μm by a hammer mill as raw material to be pulverized, and the pulverizer and flow shown in FIG. 1 are used. It was crushed. A fixed wall type air classifier was used as a classifying means for classifying the crushed powder into fine powder and coarse powder.

The acceleration tube of the collision type airflow crusher is x = 80m / m, y = 45m / m in Fig. 2. ψ = 60 ° As the secondary air inlet, we used an accelerating tube that satisfied the conditions of 8 locations in the circumferential direction (Fig. 3).

Compressed air of a = 6.4Nm ^{3 /} min (6.0kg / cm ² ) is introduced from the compressed gas supply nozzle, and the secondary air is A, C,
0.1N each from 4 locations of E and G (B, D, F and H are fully closed)
Compressed air of m ^{3 /} min (6.0 kg / cm ² ) was introduced.

The raw material to be ground was supplied from the powder raw material inlet 1 at a rate of 15 kg / hour. The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As fine powder, pulverized powder having a weight average particle diameter of 6.0 μm (measured by a Coulter counter) was collected at a rate of 15 kg / hour.

Example 2 In Example 1, the same raw material to be pulverized was pulverized by the pulverizer and the flow shown in FIG.

A fixed wall type air classifier was used as a classifying means for classifying the crushed powder into fine powder and coarse powder.

The acceleration tube of the collision type airflow crusher is x = 80m / m, y = 45m / m in Fig. 2. ψ = 45 ° As the secondary air inlet, we used an accelerating tube that satisfied the conditions of 8 locations in the circumferential direction (Fig. 3).

Compressed air of a = 6.4Nm ^{3 /} min (6.0kg / cm ² ) is introduced from the compressed gas supply nozzle, and the secondary air is A, C,
0.1N each from 4 locations of E and G (B, D, F and H are fully closed)
Compressed air of m ^{3 /} min (6.0 kg / cm ² ) was introduced.

The raw material to be ground was fed from the powder raw material inlet 1 at a rate of 16 kg / hour. The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As fine powder, pulverized powder having a weight average particle diameter of 6.0 μm (measured by a Coulter counter) was collected at a rate of 16 kg / hour.

Example 3 The same raw material to be ground as in Example 1 was ground with the grinder and flow shown in FIG.

A fixed wall type air classifier was used as a classifying means for classifying the crushed powder into fine powder and coarse powder.

The acceleration tube of the collision type airflow crusher is x = 80m / m, y = 45m / m in Fig. 2. ψ = 45 ° As the secondary air inlet, we used an accelerating tube that satisfied the conditions of 8 locations in the circumferential direction (Fig. 3).

Compressed air of a = 6.4 Nm ^{3 /} min (6.0 kg / cm ² ) was introduced from the compressed gas supply nozzle, and the secondary air was A, B,
From 6 places of C, E, H and G (D and F are fully closed), 0.1N each
Compressed air of m ^{3 /} min (6.0 kg / cm ² ) was introduced.

The raw material to be ground was supplied from the powder raw material inlet 1 at a rate of 19 kg / hour. The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As fine powder, pulverized powder having a weight average particle diameter of 6.0 μm (measured by a Coulter counter) was collected at a rate of 19 kg / hour.

Comparative Example 1 The same material to be ground as in Example 1 was ground with the grinder and flow shown in FIG.

A fixed wall type air classifier was used as a classifying means for classifying the crushed powder into fine powder and coarse powder.

Compressed air of 6.8 Nm ^{3 /} min (6.0 kg / cm ² ) was introduced from the compressed gas supply nozzle into the acceleration tube of the collision type air flow pulverizer, and the powder material feed port 1 to 12 kg / hour pulverized. The raw material was supplied. The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As fine powder, pulverized powder having a weight average particle diameter of 6.0 μm (measured by Coulter counter) was collected at a rate of 12 kg / hour.

Example 4 The same raw material to be crushed as in Example 1 was mixed with the powder raw material inlets 1 to 20 under the same configuration and conditions of the collision type air flow pulverizer as in Example 1.
The raw material to be ground was supplied at a rate of kg / hour.

The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As the fine powder, pulverized powder having a weight average particle diameter of 7.5 μm (measured by a Coulter counter) was collected at a rate of 20 kg / hour.

Example 5 The same raw material to be ground as in Example 1 was mixed with the powder raw material inlets 1 to 24 under the same structure and conditions as in the collision type air flow pulverizer as in Example 3.
The raw material to be ground was supplied at a rate of kg / hour.

The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As the fine powder, pulverized powder having a weight average particle diameter of 7.5 μm (measured by a Coulter counter) was collected at a rate of 24 kg / hour.

Comparative Example 2 The same raw material to be ground as in Example 1 was mixed with the powder raw material inlets 1 to 1 under the same configuration and conditions of the collision type air flow mill as in Comparative Example 1.
The raw material to be ground was supplied at a rate of 6.5 kg / hour.

The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As fine powder, pulverized powder having a weight average particle diameter of 7.5 μm (measured by a Coulter counter) was collected at a rate of 16.5 kg / hour.

Example 6 The same raw material to be ground as in Example 1 was mixed with the powder raw material inlets 1 to 32 under the same configuration and conditions as in the collision type air flow pulverizer as in Example 1.
The raw material to be ground was supplied at a rate of kg / hour.

The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As the fine powder, pulverized powder having a weight average particle diameter of 11.0 μm (measured by a Coulter counter) was collected at a rate of 32 kg / hour.

Example 7 The same raw material to be pulverized as in Example 1 was mixed with the powder raw material inlets 1 to 35 under the same configuration and conditions of the collision type air flow pulverizer as in Example 3.
The raw material to be ground was supplied at a rate of kg / hour.

The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As the fine powder, pulverized powder having a weight average particle diameter of 11.0 μm (measured by a Coulter counter) was collected at a rate of 35 kg / hour.

Comparative Example 3 The same raw material to be crushed as in Example 1 was mixed with the powder raw material inlets 1 to 28 under the same configuration and conditions of the collision type air flow pulverizer as in Comparative Example 1.
The raw material to be ground was supplied at a rate of kg / hour.

The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As the fine powder, pulverized powder having a weight average particle diameter of 11.0 μm (measured by a Coulter counter) was collected at a rate of 28 kg / hour.

The results of Examples 1 to 7 and Comparative Examples 1 to 3 are shown in Table 1.

Example 8 The same material to be ground as in Example 1 was ground with the grinder and flow shown in FIG.

A fixed wall type air classifier was used as a classifying means for classifying the crushed powder into fine powder and coarse powder.

The acceleration tube of the collision type air flow crusher is shown in Fig. 2 as x = 80m / m, y = 55m / m ψ = 45 ° As the secondary air inlet, we used an accelerating tube that satisfied the conditions of 8 locations in the circumferential direction (Fig. 3).

Compressed air of a = 6.4 Nm ^{3 /} min (6.0 kg / cm ² ) was introduced from the compressed gas supply nozzle, and the secondary air was A, B,
From 6 places of C, E, H and G (D and F are fully closed), 0.1N each
Compressed air of m ^{3 /} min (6.0 kg / cm ² ) was introduced.

The raw material to be ground was supplied from the powder raw material inlet 1 at a rate of 18.0 kg / hour. The crushed powder raw material is conveyed to the classifier,
The fine powder was removed as a classified powder, and the coarse powder was again charged into the acceleration tube through the charging port 1 together with the powder material.

As the fine powder, pulverized powder having a weight average particle diameter of 6.0 μm (measured by a Coulter counter) was collected at a rate of 18.0 kg / hour.

Example 9 The same material to be ground as in Example 1 was ground with the grinder and flow shown in FIG.

A fixed wall type air classifier was used as a classifying means for classifying the crushed powder into fine powder and coarse powder.

The acceleration tube of the collision type airflow crusher is x = 80m / m, y = 36m / m in Fig. 2. ψ = 45 ° As the secondary air inlet, we used an accelerating tube that satisfied the conditions of 8 locations in the circumferential direction (Fig. 3).

Compressed air of a = 6.4 Nm ^{3 /} min (6.0 kg / cm ² ) was introduced from the compressed gas supply nozzle, and the secondary air was A, B,
From 6 places of C, E, H and G (D and F are fully closed), 0.1N each
Compressed air of m ^{3 /} min (6.0 kg / cm ² ) was introduced.

The raw material to be ground was supplied from the powder raw material inlet 1 at a rate of 17.0 kg / hour. The crushed powder raw material is conveyed to the classifier,
The fine powder was removed as a classified powder, and the coarse powder was again charged into the acceleration tube through the charging port 1 together with the powder material.

As the fine powder, pulverized powder having a weight average particle diameter of 6.0 μm (measured by a Coulter counter) was collected at a rate of 17.0 kg / hour.

Example 10 The same raw material to be ground as in Example 1 was ground with the grinder and flow shown in FIG.

A fixed wall type air classifier was used as a classifying means for classifying the crushed powder into fine powder and coarse powder.

The acceleration tube of the collision type airflow crusher is x = 80m / m, y = 45m / m in Fig. 2. ψ = 45 ° As the secondary air inlet, we used an accelerating tube that satisfied the conditions of 8 locations in the circumferential direction (Fig. 3).

Compressed air of a = 6.4Nm ^{3 /} min (6.0kg / cm ² ) is introduced from the compressed gas supply nozzle, and the secondary air is A, C,
The four places of E and G (B, D, F and H are fully closed) were made into an open system, and normal pressure air was introduced.

The raw material to be ground was supplied from the powder raw material inlet 1 at a rate of 13 kg / hour. The pulverized powder raw material was conveyed to a classifier, fine powder was removed as a classified powder, and coarse powder was again charged into the accelerating tube together with the powder raw material through the charging port 1.

As fine powder, crushed powder having a weight average particle diameter of 6.0 μm (measured by a Coulter counter) was collected at a rate of 13 kg / hour, and the crushing amount was large as compared with Comparative Example 1.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a collision type airflow crusher of the present invention and a flow chart of a crushing method in which a crushing process using the crusher and a classifying process by a classifier are combined, and FIG. FIG. 4 is a cross-sectional view of an acceleration tube of the collision type airflow crusher of the present invention, FIG. 3 is a view showing one specific example of a cross section taken along the line AA ′ in FIG. 2, and FIG. FIG. 1 is a schematic cross-sectional view of a conventional collision type airflow crusher and a flowchart of a crushing method in which a crushing process using the crusher and a classifying process by a classifier are combined. 1 ... Powder raw material inlet, 2 ... Compressed gas supply nozzle 3 ... Accelerator tube, 4 ... Collision member 5 ... Discharge port, 7 ... Powder raw material 8 ... Grinding chamber, 10 ... Secondary Air inlet 13 ... Accelerator outlet, 14 ... Collision surface

Claims (5)

[Claims] 1. A collision member, comprising: an accelerating tube for accelerating the powder by high-pressure gas, a crushing chamber, and a collision member for crushing the powder ejected from the accelerating tube by a collision force. In a collision type air flow crusher provided in the crushing chamber opposite to the acceleration tube outlet, the acceleration tube is provided with a powder raw material inlet,
A collision-type airflow crusher having a secondary air inlet between a powder raw material supply port and an acceleration pipe outlet. 2. When x is the distance between the powder raw material charging port provided in the acceleration tube and the acceleration tube outlet, and y is the distance between the powder raw material charging port and the secondary air inlet, then x and y are The collision type airflow crusher according to claim 1, characterized in that 3. The method according to claim 1, wherein the introduction angle ψ of the secondary air inlet provided in the acceleration tube satisfies 10 ° ≦ ψ ≦ 80 ° with respect to the axial direction of the acceleration tube. (2) The collision type airflow crusher described in the above. 4. A pulverizing method in which powder is conveyed and accelerated by a high-pressure gas in an accelerating tube, the powder is discharged into the crushing chamber from an accelerating tube outlet, and the powder collides against an opposing collision member to pulverize. A method of pulverizing powder, characterized in that secondary air is introduced into the acceleration tube. 5. The flow rate of high-pressure gas for accelerating the powder introduced into the acceleration tube is aNm ³ / min, and the flow rate of the secondary air introduced into the acceleration tube is bNm ³ / min. The crushing is carried out under the condition satisfying
(4) The method for pulverizing the powder according to the above.