JP2704787B2 - Powder material grinding method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for pulverizing a powder raw material using a jet stream (high-pressure gas), and more particularly, the present invention relates to a method for forming an image by electrophotography. The present invention relates to a method of pulverizing a powder raw material for efficiently producing a toner or a colored resin powder for a toner.

[Related Art] A collision-type airflow pulverizer using a jet airflow conveys a powdery raw material by a jet airflow, collides the powdery raw material with a collision member, and pulverizes the powdery raw material by the impact force.

 The details will be described below with reference to FIG.

A collision member 4 is provided opposite to the outlet 13 of the acceleration tube 3 to which the compressed gas supply nozzle 2 is connected, and the supply of the powder raw material communicated to the middle of the acceleration tube 3 by the flow of the high-pressure gas supplied to the acceleration tube 3 The powder raw material 7 is sucked from the port 1 into the accelerating tube 3 and injected together with a high-pressure gas to collide with the collision surface 14 of the collision member 4 and to be pulverized by the impact. When the powder raw material 7 is used to pulverize the powder raw material to a desired particle size, a classifier is disposed between the powder raw material supply port 1 and the discharge port 5 to form a closed circuit. 7, and the coarse powder is supplied from the powder material supply port 1,
Pulverization is performed, and the pulverized material is returned to the classifier through the discharge port 5 to be classified again, and the fine powder becomes a finely pulverized material having a desired particle size.

However, in the above conventional example, since it is difficult to sufficiently disperse the powder raw material 7 sucked and introduced into the acceleration tube 3 in a high-pressure airflow, the powder flow ejected from the acceleration tube outlet 13 has a low dust concentration. It separates into a thick stream and a pale stream.

Therefore, the powder flow hitting the opposing collision surface 14 becomes partial (local), the efficiency is reduced, and the processing capacity is reduced. Further, if the processing capacity is to be increased in such a state, the dust concentration is further increased partially, so that the efficiency is further reduced.
A fused material is generated on the surface, which is not preferable.

Therefore, a pulverizer and a pulverization method with good pulverization efficiency are expected.

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

At present, the toner or the colored resin powder for the toner is prepared by melt-kneading a mixture containing at least a binder resin and a colorant or a magnetic powder (containing a third component, if necessary),
It is prepared by cooling the melt-kneaded product, pulverizing the cooled product, and classifying the pulverized product. The crushing of the cooled product is generally performed by coarse pulverization (or medium pulverization) by a mechanical impact pulverizer, and then finely pulverized by a collision type air pulverizer using a jet stream. is there.

In such a case, in the conventional collision-type airflow pulverizer and the pulverization method as shown in FIG. 5, if the processing capacity is to be further improved, a fusion product is generated on the collision surface 14 and stable production cannot be performed. Therefore, in order to more efficiently generate a toner or a colored resin powder for a toner used in an image forming method by an electrophotographic method, an efficient method of pulverizing a powder raw material that solves the above-mentioned problems is desired.

[Problems to be Solved by the Invention] In view of the above-mentioned problems of the related art, the objects of the present invention are as follows. Providing a method of pulverizing a powder raw material for efficiently pulverizing a powder mainly composed of a thermoplastic resin; A method for pulverizing a powder raw material capable of efficiently producing toner or colored resin particles for toner used in a copying machine and a printer having a heating and pressing roller fixing means; An object of the present invention is to provide a method for pulverizing a powdery raw material 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.

[Means and Actions for Solving the Problems] The present invention conveys and accelerates powder by a high-pressure gas in an accelerating tube, ejects the powder from an accelerating tube outlet into a pulverizing chamber, and connects the accelerating tube outlet into the pulverizing chamber. In the method of pulverizing a powder raw material in which the powder collides with and crushes a collision member provided in opposition, a plurality of powder raw material supply ports provided on a side surface of the acceleration tube are used in combination to form the plurality of powders. The present invention relates to a method of pulverizing a powder raw material, which comprises introducing a powder raw material into the acceleration tube from a raw material supply port.

According to the powder raw material pulverization method of the present invention, powder as a raw material to be pulverized can be efficiently pulverized to the order of several μm by utilizing a high-speed air flow. In particular, a powder of a thermoplastic resin or a powder mainly composed of a thermoplastic resin is efficiently used,
It is possible to pulverize to the order of several μm using high-speed airflow.

Here, the configuration and operation of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view of an example of an impinging airflow pulverizer used in the present invention, and a diagram showing a flowchart of a pulverizing method in which a pulverizing step using the pulverizer and a classifying step using a classifier are combined. The powder raw material 7 to be ground is supplied to the powder raw material supply port 1 provided in the acceleration tube 3.
(See FIG. 2). Accelerator tube 3
A compressed gas such as compressed air is introduced from a compressed gas supply nozzle 2 into the
Are instantaneously accelerated to have a high speed. The powdery raw material 7 ejected from the acceleration tube outlet 13 into the grinding chamber 8 at high speed
Is crushed by colliding with the collision surface 14 of the collision member 4.

In this example, as shown in FIG. 1 and FIG.
By providing seven powder material supply ports 1 and feeding the powder material, the powder is efficiently fed into the acceleration tube 3, the powder material 7 in the acceleration tube 3 is dispersed, and the acceleration tube outlet 13 is provided. The powder material 7 is more uniformly ejected from the crusher, and the powder material 7 collides with the opposing collision surface 14 efficiently, so that the pulverization efficiency can be improved more than before. The seven powder material supply ports 1 provided disperse and supply the powder material into the acceleration tube 3 and contribute to accelerate the dispersion of the powder in the acceleration tube.

Although seven supply ports are provided here, the number of supply ports is not limited to seven, and it is preferable to provide them as appropriate in consideration of powder characteristics, high-speed airflow, and the like.

The technical idea of the present invention is that the powder raw material 7 is injected into the carrier gas stream of the high-pressure gas introduced from the compressed gas supply nozzle 2, ejected from the acceleration tube outlet 13, and
In a collision-type air-flow crusher that crushes the powder material 7 by colliding the powder material 7 with the collision surface 14 of the powder, the idea that the dispersion state of the powder material 7 in the acceleration tube 3 may affect the crushing efficiency. Is based on That is, since the powder raw material 7 supplied from the powder raw material supply port 1 flows into the accelerating tube 3 in an agglomerated state, the dispersion in the accelerating tube 3 becomes insufficient. Non-uniformity in dust concentration occurs,
It was considered that the collision surface 14 could not be used effectively, and the crushing efficiency was reduced. This phenomenon becomes more conspicuous as the amount of pulverization increases.

Therefore, in order to solve this, a method of providing a plurality of powder material supply ports 1 has been devised. This is based on the idea that a plurality of powder material supply ports 1 are provided on the circumference of the acceleration tube, and the input material is dispersed and introduced into the acceleration tube 3 using the ejector effect of the acceleration tube. It is.

As another example, a cross-sectional view in which two and four powder material supply ports are provided in the acceleration tube 3 shown in FIGS. 3 and 4 (A-
A ′ section). The cross section of the acceleration tube 3 is not limited to a circular shape.

On the other hand, the inner diameter of the acceleration tube outlet 13 usually has a diameter of 10 to 100 mm, and preferably has an inner diameter 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-pulverization tends to occur, and if it exceeds 3 times,
The grinding efficiency tends to decrease.

The crushing chamber 8 of the impingement airflow crusher used in the present invention is not limited to the box type shown in FIG. Further, the collision surface 14 of the collision member 4 is not limited to be perpendicular to the axial direction of the acceleration tube 3 as shown in FIG.
It is more preferable to make the shape such that the powder ejected from 13 is efficiently reflected and makes secondary collision with the wall of the pulverizing chamber.

As described above, according to the method of the present invention, the powder material 7 can be dispersed and supplied from the plurality of powder material supply ports 1 into the acceleration tube 3, so that the powder material 7 can efficiently collide with the collision surface 14. And the crushing efficiency is improved. That is, compared to the conventional crusher,
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 raw material 7 collides with the collision surface 14 in an agglomerated state, particularly when a powder mainly composed of a thermoplastic resin is used as a raw material, a fused material is easily generated.
According to the present invention, since the particles collide with the collision surface 14 in a dispersed state, a fused material is not easily generated.

Further, in the conventional example, since the powder raw material 7 is agglomerated, excessive pulverization is liable to occur, and there is a problem that the particle size distribution of the obtained pulverized product is wide. On the other hand, according to the present invention, excessive pulverization can be prevented and a pulverized product having a sharp particle size distribution can be obtained.

[Example] Hereinafter, in order to confirm the effect of the present invention, a detailed description will be given based on an example.

Example 1 The above-mentioned raw materials were mixed with a hesh shell mixer to obtain a mixture. Next, the mixture is extruded at about 180 ° C.
And then cooled and solidified, and the cooled melt-kneaded product was roughly pulverized into particles of 100 to 1000 μm with a hammer mill. This coarsely pulverized product was used as a powder raw material 7 and pulverized by a pulverizer and a flow shown in FIG. As a classification means for classifying the pulverized powder into fine powder and coarse powder, a fixed wall type air classifier was used.

Flow rate 6.4N from compressed gas supply nozzle of impingement type air flow crusher
Compressed air of m ³ / min (pressure 6.0 kg / cm ² ) was introduced, and powder raw material 7 was supplied at a rate of 39 kg / hour from the powder raw material supply port 1 shown in FIG. The pulverized powder material 7 was conveyed to a classifier, the fine powder was removed as a classified powder, and the coarse powder was again fed into the acceleration tube 3 together with the powder material 7 from the powder material supply port 1.

As a result, pulverized powder having a volume average particle size of 7.5 μm (measured by a Coulter counter) was collected as fine powder at a rate of 39 kg / hour. Further, even after the continuous operation for 6 hours, no fused product was generated.

The particle size distribution of the toner can be measured by various methods. In the present embodiment, the measurement was performed using a Coulter counter.

In other words, the Coulter Counter TA is used as a measuring device.
-Type II (manufactured by Coulter, Inc.) is connected to an interface (manufactured by Nikkaki) that outputs the number distribution and volume distribution, and a CX-1 personal computer (manufactured by Canon). Prepare a% NaCl aqueous solution. As a measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the Coulter Counter TA-II is used, and a 100 μm aperture is used as an aperture, and particles of 2 to 40 μm are counted based on the number. The particle size distribution was measured and then the values according to this example were determined.

Example 2 The same powder raw material 7 as in Example 1 was pulverized by a pulverizer and a flow shown in FIG.

As a classification means for classifying the pulverized powder into fine powder and coarse powder, a fixed wall type air classifier was used.

Flow rate 6.4N from compressed gas supply nozzle of impingement type air flow crusher
Compressed air at m ³ / min (pressure 6.0 kg / cm ² ) was introduced, and powder raw material 7 was supplied at a rate of 34 kg / hour from the powder raw material supply port 1 shown in FIG. The pulverized powder material 7 was conveyed to a classifier, the fine powder was removed as a classified powder, and the coarse powder was again fed into the acceleration tube 3 together with the powder material 7 from the powder material supply port 1.

As a result, pulverized powder having a volume average particle diameter of 7.5 μm (measured by a Coulter counter) was collected as fine powder at a rate of 34 kg / hour. Further, even after the continuous operation for 6 hours, no fused product was generated.

Example 3 The same powder raw material 7 as in Example 1 was pulverized by a pulverizer and a flow shown in FIG.

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

Flow rate 6.4N from compressed gas supply nozzle of impingement type air flow crusher
Compressed air at m ³ / min (pressure 6.0 kg / cm ² ) was introduced, and powder material 7 was supplied at a rate of 36 kg / hour from the powder material supply port 1 shown in FIG. The pulverized powder material 7 was conveyed to a classifier, the fine powder was removed as a classified powder, and the coarse powder was again fed into the acceleration tube 3 together with the powder material 7 from the powder material supply port 1.

As a result, pulverized powder having a volume average particle diameter of 7.5 μm (measured by a Coulter counter) was collected as fine powder at a rate of 36 kg / hour. Further, even after the continuous operation for 6 hours, no fused product was generated.

Comparative Example 1 The same powder raw material 7 as in Example 1 was pulverized by a pulverizer and a flow shown in FIG.

As a classification means for classifying the pulverized powder into fine powder and coarse powder, a fixed wall type air classifier was used.

Compressed air having a flow rate of 6.4 Nm ³ / min (pressure 6.0 kg / cm ² ) is introduced from the compressed gas supply nozzle 2 into the acceleration tube 3 of the collision type air flow crusher, and 26 kg / hour is supplied from the powder material supply port 1. Powder material 7 was supplied at a ratio. The pulverized powder material 7 was conveyed to a classifier, the fine powder was removed as a classified powder, and the coarse powder was again fed into the acceleration tube 3 together with the powder material 7 from the powder material supply port 1.

As a result, ground powder having a volume average particle size of 7.5 μm (measured by a Coulter counter) was collected as fine powder at a rate of 26 kg / hour.

Table 1 shows the results of Examples 1 to 3 and Comparative Example 1 obtained as described above.

[Effects of the Invention] As described above, according to the powder raw material pulverization method of the present invention, in the method of pulverizing the powder raw material using the collision-type airflow pulverizer, the plurality of powders provided on the side surfaces of the acceleration tube are provided. The raw material supply port is used in combination, and the powder raw material is introduced into the acceleration pipe from the plurality of powder raw material supply ports, so that the powder raw material is dispersed and supplied into the acceleration pipe. And the powder material collides with the collision surface efficiently, and the pulverization efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an impinging airflow pulverizer used in the present invention and a flow chart of a pulverizing method in which a pulverizing step using the pulverizer and a classification step using a classifier are combined. FIG. 2, FIG. 3, and FIG. 4 are views showing specific examples of the cross section taken along the line AA 'in FIG. FIG. 5 is a schematic cross-sectional view of a conventional collision type airflow pulverizer,
FIG. 3 is a diagram showing a flowchart of a pulverizing method in which a pulverizing step using the pulverizer and a classifying step using a classifier are combined. DESCRIPTION OF SYMBOLS 1 ... Powder raw material supply port 2 ... Compressed gas supply nozzle 3 ... Acceleration pipe 4 ... Collision member 5 ... Discharge port 7 ... Powder raw material 8 ... Crushing chamber 13 ... Acceleration pipe Outlet 14: Impact surface 15: Powder material supply hopper tube

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhide Goseki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

(57) [Claims] The powder is conveyed and accelerated by a high-pressure gas in an accelerating tube, and the powder is ejected from an outlet of the accelerating tube into a pulverizing chamber. In a method of pulverizing a powder raw material in which powder is collided and pulverized, a plurality of powder raw material supply ports provided on a side surface of the acceleration tube are used in combination, and the powder raw material is supplied from the plurality of powder raw material supply ports. A method for pulverizing a powder raw material, wherein the method is charged into an acceleration tube. 2. The method according to claim 1, wherein the powder material is a colored resin powder material for toner.