JP3210132B2 - Method for producing toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a production method for efficiently pulverizing and classifying solid particles having a binder resin to obtain a toner for developing an electrostatic image having a predetermined particle size.

[0002]

2. Description of the Related Art In image forming methods such as electrophotography, electrostatography and electrostatic printing, toner is used to develop an electrostatic image. In recent years, along with high image quality and high definition of copiers and printers, the performance required for toner as a developer has become even more severe, the particle size of the toner has become smaller, and the toner particle size distribution has Are required to be sharp without any coarse particles and with few fine powders.

[0003] As a general method for producing a toner for developing an electrostatic image, there are a binder resin for fixing to a material to be transferred, various colorants for giving a color as a toner, and a method for giving a charge to particles. In a so-called one-component developing method as described in JP-A-54-42141 and JP-A-55-18656, various magnetic materials for imparting transportability and the like to the toner itself are used. Use, if necessary, dry-mixing release agent, fluidity imparting agent, then melt-kneaded in a general-purpose kneading device such as a roll mill or extruder,
After being cooled and solidified, it is pulverized by various pulverizers such as a jet air pulverizer or a mechanical impact pulverizer, and classified by various air classifiers so as to have a particle size required for the toner.

[0004] If necessary, a fluidizing agent, a lubricant and the like are dry-mixed to form a toner. When used in a two-component development method, various magnetic carriers and a toner are mixed and then used for image formation. As described above, in order to obtain toner particles that are fine particles, the method shown in the flowchart of FIG. 12 has conventionally been generally adopted. The coarsely crushed toner is continuously or sequentially supplied to the coarse powder classifying means and classified, and the coarse powder mainly composed of the classified coarse particles having a particle size equal to or larger than the specified particle size is sent to the crushing means and crushed, and then re-crushed. Circulated to the coarse powder classification means.

[0005] A finely pulverized toner mainly composed of particles within the other specified particle size range and particles smaller than the specified particle size is sent to a fine powder classifying means, and a medium powder mainly composed of particles having a specified particle size is used. It is classified into a body and a fine powder mainly composed of a group of particles having a specified particle size or less. As the pulverizing means, various pulverizing apparatuses are used. For pulverizing a coarsely pulverized toner mainly composed of a binder resin, a jet air flow type pulverizer using a jet air flow as shown in FIGS. An air-flow pulverizer is used.

A collision type air flow pulverizer using a high-pressure gas such as a jet gas stream conveys a powder material by a jet gas stream, injects the powder material from an outlet of an accelerating tube, and opposes an opening surface of an outlet of the accelerating tube. Then, the powder material is crushed by the impact force of the collision member.

For example, in the collision type air flow pulverizer shown in FIGS. 13 to 16, a collision member 43 is provided opposite to an outlet 45 of an acceleration tube 46 to which a high-pressure gas supply nozzle 47 is connected. The high-pressure gas sucks the powder raw material into the acceleration pipe 46 from the powder raw material supply port 40 that is communicated with the acceleration pipe 46 in the middle, and ejects the powder raw material together with the high-pressure gas to collide with the collision surface of the collision member 43. And crushed by the impact.

However, in the collision-type air-flow crusher shown in FIGS. 13 to 16, the supply port 40 for the crushed object is provided in the middle of the acceleration tube 46, so that the crushed object sucked into the acceleration tube 46 is introduced. Immediately after passing through the pulverized material supply port 40, the gas is dispersed in the high-pressure airflow while changing the flow path toward the outlet of the acceleration pipe by the high-pressure airflow ejected from the high-pressure gas supply nozzle 47, and is rapidly accelerated. In this state, the relatively coarse particles of the material to be crushed flow through the underflow in the acceleration tube due to the effect of the inertial force,
In addition, since relatively fine particles flow in the high flow portion in the acceleration tube,
Without being sufficiently uniformly dispersed in the high-pressure air flow, the material to be ground is partially concentrated and collides with the opposing collision member while being separated into a high concentration flow and a low concentration flow,
The pulverization efficiency tends to decrease, and the processing capacity tends to decrease.

In the vicinity of the collision surface 41, a portion having a high dust concentration composed of the material to be ground and the material to be ground is easily generated in the vicinity thereof. Therefore, when the material to be ground contains a low melting point substance such as a resin, Fusing, coarsening, agglomeration, and the like of the material to be ground are likely to occur. In addition, when the object to be ground has abrasion properties, local powder wear is likely to occur on the collision surface of the collision member and the accelerating tube, the frequency of replacement of the collision member increases, and continuous stable production can be said. There was a point to improve in terms of

The tip of the collision surface of the collision member has an apex angle of 11
Conical shape having 0 to 175 ° (JP-A 1-25
No. 4266) and a collision plate shape having a projection on a plane where a collision surface intersects perpendicularly with the extension of the central axis of the collision member (Japanese Utility Model Application Laid-Open No. 1-148740). In these pulverizers, it is possible to suppress the local increase in the dust concentration near the collision surface, so that the pulverized material is fused, coarsened,
Aggregation and the like can be somewhat reduced and the pulverization efficiency is slightly improved, but further improvement is desired.

For example, when obtaining a particle group having a weight average diameter of 8 μm and a coefficient of variation A of the number distribution (to be described later) of 33, a collision equipped with a classification mechanism for removing a coarse powder region is required. The raw material is pulverized to a predetermined average particle size by a pulverizing means such as an air-flow pulverizer and classified, and the pulverized material after removing the coarse powder is subjected to another classifier to remove the fine powder and remove the desired medium powder. Gaining body. In addition, the weight average particle diameter described here is data measured using a 100 μm aperture with a Coulter Counter TA-II manufactured by Coulter Electronics (USA).

In such a conventional production method, in particular, as the weight average particle diameter of the toner is 8 μm or less, and the smaller the weight average particle diameter, the lower the energy efficiency in the pulverizing means and the smaller the fine powder classifying means. The problem of lowering the classification yield occurs.

As a method for improving the yield reduction by the conventional fine powder classifying means, Jiro Nakayama and Kazuhiro Yonezawa;
As described in the monthly issue, p. 45 (1984), latest ultrafine grinding process technology, p. 347 (1985), a method has been proposed in which classification means are provided in multiple stages and a small machine is used on the downstream side. I have. With such a classification means, the yield can be improved to a certain extent, but the main focus is on reducing the reduction in classification accuracy and the reduction in classification yield mainly due to the increase in the capacity of the classification means. It is desired to further improve the classification accuracy and the classification yield.

Further, the smaller the weight average particle diameter of the toner is 8 μm or less, and the smaller the weight average particle diameter is, the more the degree of aggregation of the toner particles is increased and the more fine particles are generated. The technique for removing the ultrafine particles generated by the means becomes very difficult. Actually, as shown in FIG. 12 showing the prior art, when the fine powder classification means is one stage, the mechanism for removing the ultrafine particles is performed only once, and there is a disadvantage that the ultrafine particles cannot be completely removed.

Further, in the above-mentioned known example, the removal of the ultrafine particles can be improved when the fine powder classification means is multi-stage as compared with the case of single-stage classification. However,
The quality of the toner is not sufficient for an image, and further improvement in image quality is desired. Therefore, as a recent need, in order to realize higher definition and higher image quality, it is desired to make the toner finer, and to produce a toner having a smaller amount of ultrafine particles and a weight average particle size of 8 μm or less more efficiently. The way is long-awaited.

[0016]

SUMMARY OF THE INVENTION An object of the present invention is to provide a manufacturing method which solves the above-mentioned various problems in a conventional method for manufacturing a toner for developing an electrostatic image. That is, an object of the present invention is to provide a method for efficiently producing a toner for developing an electrostatic image having a fine particle size distribution. The present invention relates to a method of melting and kneading a mixture containing a binder resin, a colorant and an additive, cooling the melt-kneaded product, and then obtaining a fine particle product having a precise predetermined particle size distribution from a group of solid particles produced by pulverization (as toner). To be used efficiently and in good yield.

Further, the present invention provides a method for producing a powder having a weight average particle size of 3 to 8 μm.
It is an object of the present invention to provide a method for efficiently producing a toner (preferably 3 to 7 μm) for electrostatic image development and an apparatus therefor. Further, the present invention efficiently manufactures a toner for developing an electrostatic charge image having a stable, high image density, excellent durability, and excellent image quality without image defects such as fog and poor cleaning, as compared with the conventional method. It is an object of the present invention to provide a method and an apparatus for performing the method.

[0018]

The above objects are achieved by the present invention described below. That is, the present invention melts and kneads a mixture containing at least a binder resin and a colorant, cools the mixture, pulverizes the cooled material by a pulverizing means to obtain a pulverized product, and obtains a pulverized product. The classification means classifies the coarse powder into fine powder and fine powder, and the classified coarse powder is finely pulverized by an impingement airflow pulverizing means to produce fine powder. The fine powder obtained is introduced into a multi-stage fine powder classification means comprising at least two or more fine powder classification means, and a method for producing a toner for developing an electrostatic image from a powder having a predetermined particle size range obtained by classification. ,

The impingement-type airflow pulverizing means has an accelerating tube for conveying and accelerating the object to be pulverized by a high pressure gas and a pulverizing chamber for pulverizing the object to be pulverized. The object to be crushed is discharged from the acceleration tube outlet into the grinding chamber, and a projecting central portion provided opposite to the opening surface of the outlet of the acceleration tube and
A primary ground in the projecting central portion of the collision member having a periphery collision surface portion provided on the outer periphery of the projecting central portion, and the secondary pulverization primary pulverized product is a primary ground in the outer peripheral colliding part, is secondarily pulverized After the secondary pulverized material is further subjected to tertiary pulverization on the side wall in the pulverizing chamber, the powder is circulated to the coarse powder classification means, and the fine powder classified by the coarse powder classification means is subjected to at least two or more stages of fine powder classification means and to the final powder. A production method to be introduced into a multi-stage fine powder classification means comprising a multi-divided classification means in which the stage fine powder classification means is fractionated into at least three,

The multi-divided classifying means lowers the particle group in a curved line due to the Coanda effect, and separates and collects a fine powder mainly composed of a particle group having a predetermined particle size or less in the first fractionation area. 2
A medium powder mainly composed of particles of a predetermined particle size range is divided and collected in a fractionation area, and a coarse powder mainly composed of particles of a predetermined diameter or more is mainly collected and collected in a third fractionation area. And a method for circulating the coarse powder through the crushing means or the coarse powder classification means, wherein the classification point A of the fine powder classification means constituting the multi-stage fine powder classification means is represented by the following condition: A ₁ ... <A _n-1 <5.0 (2) Equation 1.5 <A _n <7.0 (3) Equation A ₁ <... <A _n-1 <A _n (4) Equation 2 ≦ n ≦ 5 [The classification point A in the formula indicates a particle diameter corresponding to a partial classification efficiency of 50%, which is called a 50% classification diameter D _P50 (μm). The partial classification efficiency was determined by the following equation (A).

[0021]

(Equation 1) D _i : i-th particle size R _c (D _i ): cumulative particle size distribution of coarse powder after classification R ₀ (D _i ): cumulative particle size distribution of raw material η _c : yield of coarse powder η (D): partial Classification efficiency

The cumulative particle size distribution referred to herein is a Coulter Counter TA manufactured by Coulter Electronics (USA).
-It is a volume cumulative particle size distribution measured using an aperture of 100 µm in Form II. Further, η indicates the number of stages of the fine powder classifying means constituting the multi-stage fine powder classifying means, the first-stage classification point of the multi-stage fine powder classification means is A ₁ , the second-stage classification point is A ₂ , and the n-th stage is A
Define _n . Incidentally, classification point of the final stage of the multi-stage fine powder classifying device is a classification point of the first fractionation zone and a second fraction region]
And the medium powder collected by the multi-stage fine powder classification step has a weight average particle diameter D _{4 of 3} to 8 μm and a coefficient of variation B of the number distribution as shown in the following condition (5): 20 ≦ B ≦ 40 [where B is the coefficient of variation (S /
D ₁ ) × 100. Here, S indicates the standard deviation in the number distribution in the medium powder, and D ₁ indicates the number average diameter (μm) in the medium powder. And a method for producing a toner for developing electrostatic images.

Further, in a preferred embodiment of the present invention, the apex angle of a central portion of the collision member projecting from the collision surface is α
(°), and when the inclination angle of the outer peripheral collision surface with respect to the vertical plane of the central axis of the acceleration tube is β (°), α and β are expressed by the following formulas: 0 <α <90, β> 0, 30 ≦ α + 2β The present invention relates to a method for producing an electrostatic image developing toner satisfying ≦ 90.

[0024]

The present invention will be described below in more detail with reference to the accompanying drawings. FIG. 1 is an example of a flowchart showing an outline of the manufacturing method of the present invention. In the present invention, a predetermined amount of the pulverized raw material is supplied to the coarse powder classification means, and is classified into coarse powder and fine powder by the coarse powder classification means. The coarse powder is introduced into the pulverizing means and pulverized, and after the pulverization, is introduced into the coarse powder classification means. The predetermined amount of fine powder is supplied to the multi-stage classification means including at least two or more stages of fine powder classification means, and the final stage of fine powder classification means is a multi-divided classification means, and is converted into at least fine powder, medium powder and coarse powder. Classified.

A predetermined amount of coarse powder is introduced into a crushing means or a coarse powder classification means. The classified medium powder is used as it is as a toner, or is mixed with an additive such as hydrophobic colloidal silica and used later as a toner. The classified fine powder is generally supplied to a melt-kneading process for producing a pulverized raw material and is reused or discarded. In the production method of the present invention, by controlling pulverization and classification conditions, the weight average particle diameter is 3 to 8 μm.
m, preferably 3 to 7 μm, and a toner having a small particle diameter having a number distribution variation coefficient A of 20 to 40 can be efficiently produced.

FIG. 2 shows an example of the apparatus system of the present invention. In this apparatus system, a pulverized raw material serving as a toner powder raw material is supplied to a coarse powder classifier 1 via a first constant feeder 102.
09, and the classified fine powder is collected by the cyclone 10
, And is introduced into the first-stage fines classifier 220 via the fine powder supply injection feeder 202. The coarse powder classified by the coarse powder classifier 109 is sent to the pulverizer 108 to be pulverized, and then re-introduced to the coarse powder classifier 109 together with the newly added raw material.

The fine powder introduced into the first-stage fine powder classifier 220 is classified into primary fine powder and quasi-medium powder, and the primary fine powder is collected by the collecting cyclone 203. Junchuko is through the medium powder supply injection feeder 221 semi further fed to through a collecting cyclone 201 third constant weight feeder 210 and then through the vibration feeder 103, through the semi-middle-powder supply nozzle 116, It is introduced into the second stage fine powder classifier (multi-divider classifier) 101. The quasi-medium powder introduced into the second stage fine powder classifier (multi-divider classifier) 101 is classified into a secondary fine powder, a medium powder and a coarse powder.
After being collected at 06, the pulverizer 108 (or the coarse powder classifier 1)
09). The secondary fine powder and the medium powder are collected by collection cyclones 104 and 105, respectively.

FIG. 4 is a schematic sectional view of a pulverizing means used in the present invention and a flow chart of a pulverizing apparatus combining an impingement type air pulverizer and a coarse powder classifier using the pulverizer. The powder raw material 7 to be ground is
Is supplied to the accelerating tube 3 from the powder material inlet 1 provided in the pulverizer wall 11 above. A compressed gas such as compressed air is introduced into the acceleration tube 3 from the compressed gas supply nozzle 2, and the powder raw material 7 supplied to the acceleration tube 3 is instantaneously accelerated to have a high speed. The powdery raw material 7 discharged from the acceleration pipe outlet 13 into the pulverizing chamber 8 at a high speed collides with the collision surface of the collision member 4 and is pulverized. In the crusher shown in FIG. 4, the collision surface of the collision member has a protruding central portion 1 which is in the form of a cone.
4 and an outer peripheral collision surface 15 around the projecting central portion for further crushing the primary crushed material crushed at the projecting central portion by collision. Further, the pulverizing chamber 8 has a side wall 6 for tertiary pulverizing the secondary pulverized material pulverized at the outer collision surface by collision.

FIG. 5 shows a cross-sectional plan view of FIG. 4 and will be described in more detail. As described above, by providing the conical projection 14 having a central portion protruding on the raw material collision surface, the solid-gas mixed flow of the pulverized raw material and the compressed air ejected from the accelerating tube causes the primary After being pulverized and further pulverized at the outer peripheral collision surface 15, it is pulverized tertiarily at the pulverizing chamber side wall 6. At this time, the vertex angle α (°) of the central portion of the collision member protruding from the collision surface and the inclination angle β (°) of the outer collision surface with respect to the face of the central axis of the acceleration tube are 0 <α <90, β. When> 0 30 ≦ α + 2β ≦ 90, grinding is performed very efficiently.

When α ≧ 90, the reflected flow of the pulverized material pulverized on the projection surface undesirably disturbs the flow of the solid-gas mixed flow ejected from the accelerating tube. When β = 0, that is, when the outer peripheral collision surface 15 is perpendicular to the solid-gas mixed flow as shown in FIG. 13, the reflected flow at the outer peripheral collision surface flows toward the solid-gas mixed flow. Turbulence of the solid-gas mixed flow is not preferred. When β = 0, the powder concentration on the outer peripheral collision surface increases, and when a powder of a thermoplastic resin or a powder containing a thermoplastic resin as a main component is used as a raw material, the powder concentration on the outer peripheral collision surface is increased. Kimonos and agglomerates are easily formed. When such a fusion occurs, stable operation of the apparatus becomes difficult.

When α and β satisfy α + 2β <30,
Since the impact force of the primary pulverization on the projection surface is weakened, the pulverization efficiency is lowered, which is not preferable. Α and β are α + 2
When β> 90, the reflected flow at the outer peripheral collision surface flows downstream of the solid-gas mixed flow, so that the impact force of the tertiary pulverization on the side wall of the pulverization chamber is weakened, and the pulverization efficiency is reduced. As described above, α and β are 0 <α <90, β> 0, 30 ≦ α + 2
β ≦ 90, more preferably 10 <α <80,
When 5 <β <40 is satisfied, as shown in FIG.
The secondary and tertiary pulverization are performed efficiently, and the pulverization efficiency can be improved.

As compared with the conventional crusher, the number of collisions is increased,
The feature of the present invention is to make the collision more effective, and the pulverization efficiency can be improved, and the generation of fused material at the time of pulverization can be prevented, and stable operation can be performed. The configuration of the pulverizer used in the present invention is not limited to the configuration shown in FIG. FIG. 6 is a schematic sectional view of a pulverizer according to another preferred embodiment of the present invention, and a flow chart of a pulverizer that combines a pulverizing step using the pulverizer and a classification step using a classifier, and FIG. A
FIG. 8 is an enlarged cross-sectional view taken along line A-B of FIG. 6.

The pulverizer shown in FIG. 6 will be described. An accelerating tube 21 for conveying and accelerating a material to be pulverized by a high-pressure gas, and a collision member 3 having a collision surface provided opposite to the outlet of the accelerating tube.
0, the acceleration pipe 21 has a Laval nozzle shape, and a high-pressure gas ejection nozzle 23 is disposed upstream of a throat portion of the acceleration pipe 21. The outer wall of the high-pressure gas ejection nozzle 23 and the throat portion 2
An object supply port 24 is provided between the inner walls of the
The grinding chamber provided in connection with the outlet of No. 1 has a circular cross section in the axial direction.

The crushed material supplied from the crushed material supply cylinder 25 is supplied to the inner wall of the acceleration tube throat portion 22 of the acceleration tube 21 having a Laval nozzle shape whose central axis is disposed in a vertical direction, and the center of the acceleration tube 21 is The material reaches a pulverized material supply port 24 formed between the central axis and the outer wall of the high-pressure gas ejection nozzle 23 coaxially. On the other hand, the high-pressure gas is introduced from the high-pressure gas supply port 26, passes through the high-pressure gas chamber 27, passes through one, preferably a plurality of high-pressure gas introduction pipes 28, and moves from the high-pressure gas ejection nozzle 23 toward the acceleration pipe outlet 29. It gushes while expanding rapidly.

At this time, due to the ejector effect generated near the accelerating tube throat portion 22, the object to be ground is directed from the object to be ground supply port 24 toward the acceleration tube outlet 29 while being entrained by the gas coexisting therewith. And accelerates rapidly while being uniformly mixed with the high-pressure airflow in the accelerating tube throat portion 22. The uniform solid-gas mixed airflow is uniformly distributed on the collision surface of the collision member 30 arranged opposite to the acceleration tube outlet 29 without unevenness of the dust concentration. Clash in state. The impact force generated at the time of collision is given to sufficiently dispersed individual particles (objects to be ground), so that very efficient grinding can be performed. The pulverized material pulverized on the collision surface of the collision member 30 further repeats collision between the pulverizing chamber side wall 32 and the surface of the collision member 30 to further increase the pulverization efficiency, and the pulverized material disposed behind the collision member 30 It is discharged from the discharge port 33.

The collision surface of the collision member has a projecting central portion 14 and an outer peripheral collision for further crushing the primary pulverized material crushed at the projecting central portion around the projecting central portion by further collision. It has a surface 15. Further, the pulverizing chamber 34 has a side wall 32 for tertiary pulverization of the secondary pulverized material secondary pulverized on the outer peripheral collision surface by collision. Similar to the pulverizer of FIG. 4, the object to be pulverized is primarily pulverized on the surface of the projection on the collision surface, further pulverized at the outer collision surface 15, and then tertiary pulverized at the pulverizing chamber side wall 32.

In the crusher shown in FIG. 9, the center axis of the accelerating tube is disposed in a vertical direction, and the material to be crushed is supplied from between the inner wall of the accelerating tube and the outer wall of the high-pressure gas jet nozzle. By supplying the same direction of supply, the material to be ground can be dispersed in a high-pressure air stream that is uniformly jetted without deviation due to the dust concentration. Another device used in the present invention is shown in FIGS. Note that FIG.
It is sectional drawing in a line.

The pulverizer shown in FIG. 9 will be described. The pulverizer is provided with an accelerating tube 21 for conveying and accelerating a powdery raw material by a high-pressure gas, and a collision surface for pulverizing the powder ejected from the accelerating tube 21 by a collision force. A thrust portion 36 of a Laval-shaped accelerating tube 21 and an accelerating tube outlet, wherein the impingement member 30 is provided to face the accelerating tube outlet. 37, a powder material supply port 24 in the entire circumferential direction of the accelerating tube is provided, and the crushing chamber has a substantially circular cross section, and the collision member 3
This is a collision type airflow pulverizer provided with a pulverized material discharge port 33 at the rear.

The center axis of the accelerating tube 21 has a vertical direction, and the collision surface of the collision member 30 has a protruding central portion 14 and pulverized around the protruding central portion at the protruding central portion. It has an outer peripheral collision surface 15 for further crushing the primary crushed material by collision. The pulverizing chamber 34 has a side wall 32 for tertiary pulverizing the secondary pulverized material secondary pulverized on the outer peripheral collision surface by collision. The operation of the high-pressure gas will be described. First, the high-pressure gas enters from the high-pressure gas supply ports 27 on the left and right sides of the high-pressure gas chamber 27, and after the arteries are made uniform, such as pressure fluctuations, the central portion of the supply tube 25 for the material to be pulverized. From the Laval nozzle 35 provided to the acceleration tube 21.

The accelerating tube 21 also has a flared Laval shape like the Laval nozzle 35, and the high-pressure gas flowing into the accelerating tube 21 is expanded and accelerated to a supersonic region.
In the process, the high-pressure gas is decompressed, and when the gas exits the acceleration tube 21, the pressure of the gas becomes substantially the same as the pressure of the pulverizing chamber 34. On the other hand, in the circular crushing chamber 34, the crushing chamber 34
When the gas inside is sucked, a suction flow is generated inside the grinding chamber.
Then, the surface of the collision member 30 is reduced in pressure by the action of the suction flow. The shape of the crushing chamber is not limited to this. The jet flow from the accelerating tube 21 is further accelerated by the depressurizing action on the surface of the collision member 30, and the collision member 3
Hit the zero surface. At this time, the object to be pulverized is primarily pulverized on the surface of the protrusion 14 on the collision surface of the collision member 30, further pulverized at the outer collision surface 15, and then tertiarily pulverized at the pulverization chamber side wall 32.

Next, the operation of the supplied powdery raw material will be described. The powder raw material, which is the material to be crushed, is supplied from the material supply tube 25 to be crushed. The supplied powder raw material is sucked and discharged to the acceleration tube 21 from the powder raw material supply port 24 at the lower part of the supply cylinder. The principle of the suction and discharge of the raw material is based on the ejector effect caused by the expansion and decompression of the high-pressure gas in the acceleration tube.
At this time, since the powder material supply port 24 is provided in the entire circumferential direction of the acceleration tube between the throat portion of the acceleration tube having the Laval shape and the exit of the acceleration tube, the powder material is sufficiently dispersed and accelerated by the high-speed airflow.

It is preferable that the powder material supply port 24 is provided in the entire circumferential direction or in a plurality (n ≧ 2). If the powder material supply port is provided at one location, the dispersion state of the material in the accelerating tube becomes uneven, which is not preferable because it lowers the pulverization efficiency. The powdery raw material dispersed and sucked in the accelerating tube 21 in this manner is completely dispersed by the high-speed airflow radiated from the Laval nozzle 35 provided at the center of the crushed object supply cylinder 25. Next, the dispersed raw material is accelerated by a high-speed airflow flowing through the inside of the accelerating tube 21, and becomes a supersonic solid-gas mixed flow. This solid-gas mixed flow is supplied to the accelerating tube 21
After exiting, the jet becomes a solid-gas mixed jet, and collides with the collision member 30 under the same action as the jet described above.

In the pulverizer shown in FIG. 9, the center axis of the accelerating tube is disposed vertically, and a specific raw material supply method is employed. And an excellent pulverization processing ability can be obtained.
Also, by uniformizing the dust concentration by strong dispersion of the material to be ground,
Local fusion and abrasion of the material to be ground in the collision member, the acceleration tube, and the grinding chamber can be significantly reduced as compared with the conventional collision-type airflow pulverizer, and the apparatus can be stably operated.

The pulverizers of FIGS. 6 and 9 differ from the pulverizer of FIG. 4 in the method of charging the raw materials into the accelerating tube, and can disperse the powder raw material in the accelerating tube more uniformly. ,
Therefore, the pulverization efficiency can be further improved. still,
6 and 9, α and β are 0 <α <.
When 90, β> 0, and 30 ≦ α + 2β ≦ 90, the primary, secondary, and tertiary pulverization can be performed efficiently, and the pulverization efficiency can be improved.

In the crusher of the present invention, it is preferable that the inner diameter of the outlet of the acceleration tube has an inner diameter smaller than the diameter b of the collision member. It is preferable that the tip of the central portion of the protrusion protruding from the collision surface of the collision member substantially coincides with the center axis of the accelerating tube from the viewpoint of uniformity of pulverization. The distance a between the accelerator tube outlet and the end of the collision surface of the collision member is 0.1 mm of the diameter of the collision member.
It is preferably from 2.5 to 2.5 times, more preferably from 0.2 to 1.0 times. If it is less than 0.1 times, the dust concentration in the vicinity of the collision surface becomes high, and if it exceeds 2.5 times, the impact force is weakened and the pulverization efficiency tends to decrease.

The shortest distance c between the end of the collision surface of the collision member and the side wall (inner wall) of the pulverizing chamber is equal to 0.1 mm of the diameter b of the collision member.
It is preferably 1 to 2 times or less. If it is less than 0.1 times, the pressure loss during passage of the high-pressure gas is large, not only lowering the pulverization efficiency, but also the flow of the pulverized material tends not to be smooth. In this case, the effect of the tertiary collision of the object to be crushed is reduced, and the crushing efficiency is reduced.
The shape of the crushing chamber is not particularly limited as long as the distance between the end of the collision surface of the collision member and the side wall of the crushing chamber satisfies the above value.

An air flow classifier is used as a coarse powder classification means used in the present invention. For example, a DS type classifier manufactured by Nippon Pneumatic Industries, a micron separator manufactured by Hosokawa Micron Corporation, an ATP type classifier, a turbo classifier manufactured by Nisshin Engineering Co., Ltd. can be used. By using such an airflow classifier in combination with the above-mentioned collision airflow pulverizer, the incorporation of fine powder into the pulverizer is suppressed or prevented well, and excessive pulverization of the pulverized material is prevented. The classified coarse powder is smoothly supplied to the crusher, further uniformly dispersed in the accelerating tube, and satisfactorily crushed in the crushing chamber, so that the yield of the crushed material and the energy efficiency per unit weight can be increased. .

In the fine powder classifying means constituting the multi-stage fine powder classifying means used in the present invention, a means for providing the multi-divided classification area, which is the last-stage fine powder classifying means, is shown in, for example, FIG. A multi-segmentation classifier of the type shown can be exemplified as one of the specific examples. In FIG. 11, the side wall is 1
22 and 124, the lower wall has a shape indicated by 125, and the lower wall 123 and the lower wall 125 are provided with knife edge type classification edges 117 and 118, respectively. , 118, the classification zone is divided into three. A raw material supply nozzle 116 that opens to the classification chamber is provided below the side wall 122, and a Coanda block 126 that is bent downward in the direction of extension of the tangent at the bottom of the nozzle and that draws a long elliptical arc is provided.

The upper wall 127 of the classifying chamber has a knife-edge type inlet edge 119 in the lower part of the classifying chamber, and further, the upper part of the classifying chamber is provided with air inlet pipes 114 and 115 opening to the classifying chamber. The intake pipes 114 and 115 have a first
Gas introduction adjusting means 120, second gas introduction adjusting means 121
And static pressure gauges 128 and 129 are provided. Classification edge 1
The positions of the inlets 17, 118 and the inlet edge 119 differ depending on the type of fine powder and the desired particle size. Discharge ports 111, 112, and 113 that open into the room are provided on the bottom of the classifying chamber corresponding to the respective dividing areas. Outlet 11
Opening / closing means such as valve means may be provided in each of 1, 112 and 113. The fine powder supply nozzle 116 is composed of a right-angled cylindrical portion and a pyramid-shaped cylindrical portion. When the ratio of the inner diameter of the right-angled cylindrical portion to the inner diameter of the narrowest portion of the pyramid-shaped cylindrical portion is set to 20: 1 to 1: 1, good introduction is achieved. Speed is obtained.

The classification operation in the multi-segment classification area configured as described above is performed, for example, as follows. Outlet 11
The pressure in the classification area is reduced through at least one of 1, 112, and 113, and the flow rate of 50 to 30 is generated in the raw material supply nozzle 116 opened in the classification area by the airflow flowing by the reduced pressure.
Fine powder is supplied to the classification area through the fine powder supply nozzle 116 at a speed of 0 m / sec. When the fine powder is supplied to the classification area at a flow rate of less than 50 m / sec, it is difficult to sufficiently disintegrate the fine powder, and the classification yield and the classification accuracy are likely to be lowered. When the fine powder is supplied to the classification region at a flow rate exceeding 300 m / sec, the particles tend to be crushed due to the collision of the particles, and the fine particles are easily generated, so that the classification yield tends to decrease.

The supplied fine powder moves along a curved line 130 due to the action of the Coanda block 126 due to the Coanda effect and the action of a gas such as air flowing in at that time, and the size of each particle size and the size of the weight are increased. Classified according to. Assuming that the specific gravity of the particles is the same, the large particles (coarse powder) are outside the airflow (that is, the first particles on the left side of the classification edge 118).
The intermediate powder (particles having a particle size within the specified range) is classified into a second fractionation area between the classification edges 118 and 117, and the fine powder (particles having a particle size equal to or smaller than the specified particle size) is classified. Edge 117
Is classified into the third fractionation area on the right side of The classified coarse powder is discharged from the pulverized material at the discharge port, the medium powder is discharged from the discharge port 112, and the fine powder is discharged from the discharge port 113.

For the introduction of the fine powder into the classification area, a method of sucking and introducing using the suction force of a cyclone; providing a fine powder supply nozzle with air conveying means such as injection;
There is a method of introducing by a suction force from a cyclone and a force of compressed air from an injection, or a pressurized introduction.
An introduction method using an air conveying means such as suction introduction or injection is preferable because the sealability of the apparatus system is not required as compared with pressurized introduction. FIG. 3 shows an example of an apparatus in which the injection 147 is attached to the fine powder supply nozzle. Examples of the multi-divider classifier that is a fine powder classifier include a classifier having a Coanda block, such as an Elbow Jet manufactured by Nippon Steel Mining Co., and utilizing the Coanda effect.

Since the size of the classification area of the multi-segment classifier 101 is usually [10 to 50 cm] × [10 to 50 cm], three or more types of fine powder can be instantaneously obtained within 0.1 to 0.01 seconds. It can be classified into particles. When the multi-segmentation classifier 101 is fractionated into three, the multi-segmentation classifier 101 converts the fine powder into a coarse powder (particles having a specified particle size or more), a medium powder (particles having a specified particle size), and a fine powder. It is divided into bodies (particles having a specified particle size or less). Thereafter, the coarse powder is returned to the pulverizer 108 through the discharge conduit 111 via the collection cyclone 106.

The coarse powder may be returned to the coarse powder classifier 109 or the first quantitative feeder 102. In order to reduce the load on the first classifier 109 and reliably perform pulverization by the pulverizer 108, it is more preferable to return the coarse powder directly to the pulverizer 108. The intermediate powder is discharged out of the system via the discharge conduit 112, collected by the collection cyclone 105, and collected to become the toner product 151. The fine powder is discharged out of the system via the discharge conduit 113, collected by the collection cyclone 104, and then collected as the fine powder 141 having a specified outside diameter. The collecting cyclones 104, 105 and 106 supply fine powder to the nozzle 11
It also functions as a suction pressure reducing means for sucking and introducing into the classification area via 6.

The number of stages of the fine powder classification means constituting the multi-stage fine powder classification means is preferably from 2 to 5 stages, more preferably from 2 to 4 stages, still more preferably from 2 to 3 stages. In this case, the fine powder classification means at the final stage is preferably a multi-division classification means. When the number of stages of the fine powder classification means constituting the multi-stage fine powder classification means is one,
That is, in the case of the single-stage classification, the chance of removing the ultrafine particles (the number of times) is small, so that the image quality is reduced, particularly the fogging property is reduced. In particular, when the weight average particle diameter of the toner is 8 μm or less,
This tendency is remarkable as the weight average particle size becomes smaller. Further, when the number of fine powder classification means in the multi-stage fine powder classification step is more than five, the image quality (particularly, fogging property) is good, but the apparatus cost is increased, and the production cost is also increased, which is not preferable.

In the fine powder classifying means constituting the multi-stage fine powder classifying means, the combination of classifiers which are fine powder classifying means excluding the fine powder classifying means at the last stage may be either the same model or a combination of different models. As a result of intensive studies, the classification point of fine powder classifying means constituting a multistage fine powder classifying hand stage (1) to (4) very high removal efficiency of Microparticles by setting the classification conditions so as to satisfy the
It has also been found that the classification yield can be improved satisfactorily.

Therefore, ultrafine particles can be efficiently removed,
Improves image quality (especially fogging) and classifies
To improve the yield well, configure multi-stage fine powder classification means
Classification point A of the fine powder classifying means is calculated from the following condition (1).
It is good to set to formula (4). Equation (3) under the following condition
A_n-1> An, the removal efficiency of the ultrafine particles is good
Is not preferred because the classification yield decreases. (1) Formula 1.0 <A ₁…… <A_n-1<5.0 (2) Formula 1.5 <A_n<7.0 (3) Formula A_n-1<A_n (4) Formula 2 ≦ n ≦ 5 [A classification point A in the formula is a particle corresponding to a partial classification efficiency of 50%.
50% classification diameter D_P50(Μm)
Is shown. n is the fine powder constituting the number of stages of the multistage fine powder classification means
Shows the number of stages of classification means. ] This classification point is based on
Depending on the particle diameter, the desired medium powder particle diameter and the true specific gravity of the powder.
Optimal conditions may be adopted.

In the present invention, the pulverizing step shown in the flow chart of FIG. 1 is not limited to this. For example, two pulverizing means and two pulverizing means or one There may be more than one means each. What kind of combination constitutes the pulverizing step may be appropriately set according to a desired particle diameter, a constituent material of toner particles, and the like. In this case, where the coarse powder to be returned to the pulverizing step is to be returned may be appropriately set. The multi-divided classifier as the fine powder classification means at the last stage of the fine powder classification means constituting the multi-stage fine powder classification means is not limited to the shape shown in FIG. An optimum shape may be adopted depending on the particle diameter and the true specific gravity of the powder.

The raw material to be introduced into the coarse powder classification means is 2 m
m or less, preferably 1 mm or less. A material obtained by introducing the pulverized raw material into the medium pulverization step and pulverizing to about 10 to 100 μm may be used as the raw material in the present invention. In the conventional pulverization-classification method, in particular, the toner has a weight average particle diameter of 8 μm.
m or less, the smaller the weight average particle diameter, the lower the energy efficiency in the pulverizing means and the lower the classification yield in the fine powder classification means, and the smaller the weight average particle diameter of the toner. As the degree of agglomeration of toner particles increases and the generation of extra fine particles increases, the extra fine particles generated by the pulverizing means cannot be completely removed by the fine powder classifying means, so that the image quality decreases (particularly, the fogging property). I was invited.

In the conventional pulverization-classification method, as a method for improving the yield of the fine powder classification means, an attempt has been made to use a multi-stage fine powder classification means, but the reduction in classification accuracy is mainly caused by an increase in the capacity of the classification means. The purpose of this method is to reduce the decrease in the classification yield, and although this method can improve the classification yield to some extent, the efficiency of removing ultrafine particles is also reduced by a single-stage fine powder classification means. However, the image quality (especially fogging) was not satisfactory.

Further, in the conventional pulverization-classification method, it is required that a coarse particle group having a certain specified particle size or more is completely removed from the powder at the end of the pulverization. For this reason, the grinding process requires more grinding power than necessary,
As a result, excessive pulverization was caused, resulting in reduction in pulverization efficiency. This development becomes more conspicuous as the particle size of the powder becomes smaller. Particularly, when a medium powder having a weight average particle size of 3 to 8 μm is obtained, the efficiency is significantly reduced.

The method of the present invention uses a highly efficient grinding means
The toner raw material can be pulverized with high energy efficiency, and good production cost can be reduced in the pulverization process. Further, by providing fine powder classification means in multiple stages, constituting a multi-stage fine powder classification means, and controlling the classification point stepwise, a good improvement in the classification yield in the fine powder classification means (multi-stage fine powder classification means) is obtained,
Moreover, the removal efficiency of the ultrafine particles can be extremely increased.

Furthermore, in the method of the present invention, the coarse powder particles and the fine powder particles are simultaneously removed by using the multi-divided classification means at the final stage of the fine powder classification means constituting the multi-stage fine powder classification means. Therefore, even if a coarse particle group having a certain particle size or more is contained in a certain ratio in the particle size of the powder at the end of the pulverization, the fine particles are satisfactorily removed by the multistage classification means in the final stage of the multistage fine powder classification process. Therefore, the restriction in the pulverizing step is reduced, the performance of the pulverizer can be maximized, the pulverization efficiency is improved, and there is little tendency to cause over-pulverization. For that reason,
The removal of fine powder can also be performed very efficiently, and the classification yield can be further improved.

In the conventional classification method for classifying the medium powder and the fine powder, since the residence time during the classification is long, agglomerates of fine particles which cause fogging of the developed image are easily generated. When aggregates are formed, it is generally difficult to remove the aggregates from the medium powder. However, according to the method of the present invention, even if the aggregates are mixed in the pulverized material, the Coanda effect and / or the high-speed movement Agglomerates are crushed by the impact of the crushing and are removed as fine powder, and even if there are agglomerates that have escaped crushing, they can be simultaneously removed to the coarse powder area, making it possible to remove agglomerates efficiently. is there.

The synergistic effect of using the high-efficiency pulverizing means, the multi-stage fine powder classifying means having a controlled classification point, and the multi-stage classifying means in the final stage of the fine powder classifying means constituting the multi-stage fine powder classifying means results in low production cost and extremely low cost. It is possible to produce a toner having an extremely small amount of fine particles and further improved image quality (especially, fogging property). Therefore, the production method of the present invention can be preferably used for producing toner particles used for developing an electrostatic image.

To prepare a toner for developing an electrostatic image, a colorant or magnetic powder, a vinyl-based or non-vinyl-based thermoplastic resin, a charge control agent, and other additives as necessary are added to a Henschel mixer or a ball mill. After thoroughly mixing with a mixer such as, a hot roll, kneader, extruder is melted, kneaded and kneaded using a hot kneader to disperse the pigments or dyes while the resins are mutually compatible. Alternatively, the toner can be obtained by melting, cooling, solidifying, and then pulverizing and classifying.

In the toner production process, the production method of the present invention is used in the pulverization process and the classification process. Next, the constituent materials of the toner will be described. When a heat and pressure fixing device or a heat and pressure roller fixing device having a device for applying oil is used as the binder resin used for the toner, the following binder resins for toner can be used.

For example, homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene and substituted products thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene Copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer; polyvinyl chloride, phenolic resin, natural resin modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane resin, polyamide resin, furan resin, Epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone indene resins, petroleum resins and the like can be used.

In a heat and pressure fixing method or a heat and pressure roller fixing method in which little or no oil is applied, so-called offset development in which a part of a toner image on a toner image support member is transferred to a roller, and An important issue is the adhesion of the toner to the toner image supporting member. Toners that fix with less heat energy tend to block or cake during storage or in a developing unit, and these problems must also be considered at the same time. In these developments, the physical properties of the binder resin in the toner are the most important. However, according to the study of the present inventors, if the content of the magnetic substance in the toner is reduced, the toner image is not supported during fixing. Although the adhesion of the toner to the body is improved, offset tends to occur, and blocking or caking tends to occur. Therefore, in the present invention, when using the heating / pressing roller fixing method in which almost no oil is applied, the selection of the binder resin is more important. Preferred binders include cross-linked styrenic copolymers or cross-linked polyesters.

Examples of comonomers for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.
Duplex such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a bond or a substituted product thereof; for example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like; and a substituted product thereof; for example, vinyl chloride, vinyl acetate Vinyl esters such as vinyl benzoate; ethylene olefins such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl methyl ether; Sulfonyl ethyl ether, vinyl monomers such as such vinyl ethers and vinyl isobutyl ether is used alone or two or more.

As the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene, etc .; for example, ethylene glycol diacrylate, Ethylene glycol dimethacrylate,
Carboxylic esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinylether, divinylsulfide, divinylsulfone; and compounds having three or more vinyl groups Are used alone or as a mixture.

When the pressure fixing method or the light heat pressure fixing method is used, a binder resin for a pressure fixing toner can be used.
Polymethylene, polyurethane elastomer, ethylene-
Ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, paraffin and the like. Further, it is preferable that a charge control agent is mixed (internally added) to the toner particles and used in the toner.

The charge control agent makes it possible to control the amount of charge optimally according to the development system. In particular, in the present invention, it is possible to further stabilize the balance between the particle size distribution and the charge. By using the above, it is possible to further clarify the function separation and the complementarity for higher image quality for each particle size range described above. As the positive charge control agent, denatured products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate alone or Two or more types can be used in combination. Of these, charge control agents such as nigrosine compounds and quaternary ammonium salts are particularly preferably used.

The general formula

Embedded image R ₁ : H, CH ₃ R ₂ , R ₃ : a monopolymer of a monomer represented by a substituted or unsubstituted alkyl group (preferably C _{1 to} C ₄ ) or styrene or acrylate as described above; Copolymers with polymerizable monomers such as methacrylates can be used as positive charge control agents, in which case these charge control agents also act as (all or part of) the binder resin .

As the negative charge control agent, for example, an organometallic complex and a chelate compound are effective. Examples thereof include aluminum acetylacetonate, iron (II) acetylacetonate, chromium 3,5-ditert-butylsalicylate, Zinc and the like are preferable, and an acetylacetone metal complex, a salicylic acid-based metal complex or a salt is particularly preferable, and a salicylic acid-based metal complex or a salicylic acid-based metal salt is particularly preferable.

The above-mentioned charge control agent (having no action as a binder resin) is preferably used in the form of fine particles. In this case, the number average particle size of the charge control agent is
Specifically, it is preferably 4 μm or less (more preferably 3 μm or less). When internally added to the toner, such a charge control agent is preferably used in an amount of 0.1 to 20 parts by weight (more preferably 0.2 to 10 parts by weight) based on 100 parts by weight of the binder resin.

When the toner is magnetic, the magnetic material contained in the magnetic toner may be magnetite, γ-iron oxide,
Ferrite, iron oxides such as iron-rich ferrite; metals such as iron, cobalt, nickel or these metals and aluminum, cobalt, copper, lead, magnesium, tin, zinc,
Examples include alloys with metals such as antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

These ferromagnetic materials have an average particle size of 0.1 to 1
μm, and preferably about 0.1 to 0.5 μm.
The amount is 60 to 110 parts by weight, preferably 65 to 100 parts by weight, per 100 parts by weight of the resin component.
As the colorant used in the toner, conventionally known dyes and / or pigments can be used. For example, carbon black, phthalocyanine blue, peacock blue, permanent red, lake red, rhodamine lake, Hanza yellow, permanent yellow, benzidine yellow and the like can be used. As its content, 0.1 to 20 parts by weight based on 100 parts of the binder resin,
It is preferably 0.5 to 20 parts by weight, more preferably 12 parts by weight or less, more preferably 0.5 to 9 parts by weight, in order to improve the transparency of the OHP film on which the toner image is fixed.

[0079]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Example 1 100 parts by weight of styrene-butyl acrylate-divinylbenzene copolymer (monomer polymerization weight ratio: 80.0 / 19.0 / 1.0, weight average molecular weight Mw: 350,000) Magnetic iron oxide (average particle size: 0,1) 18 μm) 100 parts by weight ・ Nigrosine 2 parts by weight ・ Low molecular weight ethylene-propylene copolymer 4 parts by weight

After the above-mentioned ingredients were mixed well with a Henschel mixer (Model FM-75, manufactured by Mitsui Miike Kakoki), a twin-screw kneader (PCM-30) set at a temperature of 150 ° C.
(Made by Ikegai Iron Works). The obtained kneaded material was cooled and coarsely pulverized with a hammer mill to 1 mm or less to obtain a coarsely crushed material for toner production. The obtained toner pulverized raw material was pulverized and classified by the apparatus system shown in FIG. The collision-type airflow crusher 108 uses an apparatus having a configuration shown in FIG. 4, and the collision-type airflow crusher has a collision surface having an apex angle of 50 ° (α = 50).
°), and the inclination angle of the outer peripheral collision surface with respect to the vertical plane of the center axis of the accelerating tube was 10 ° (β-10 °) (α + 2β = 70 °).

The diameter of the collision member is 90 mm (b = 90
mm) and the distance between the end of the collision surface and the exit of the accelerator is 50 m
m (a = 50 mm), and the shortest distance from the crushing chamber wall is 2
0 mm (c = 20 mm), and the grinding chamber was box-shaped. 30 kg / hr. , And the classified coarse powder was introduced into the impingement type air current pulverizer at a pressure of 6.0 kg / cm.
² (G), using compressed air of 6.0 Nm ³ / min,
After the pulverization, the mixture was circulated again to the classifier to perform closed circuit pulverization.

As a result, a finely pulverized toner product having a weight average diameter of 6.7 μm was obtained as classified fine powder. In addition, this pulverized product did not generate a fused product, could perform a stable pulverizing operation, and had a sharp particle size distribution substantially free of coarse particles of 16 μm or more. 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.

That is, a Coulter Counter TA-II type (manufactured by Coulter Inc.) is used as a measuring device, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting a number distribution and a volume distribution.
And CX-1 personal computer (manufactured by Canon Inc.), and the electrolyte is 1% N using 1 grade sodium chloride.
An aqueous aCl solution is prepared. As a measuring method, a surfactant, preferably an alkylbenzene sulfonate, of 0.1 to 5 m is used as a dispersant in 100 to 150 ml of the electrolytic aqueous solution.
and 2 to 20 mg of the measurement sample. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and by the Coulter counter TA-II,
Using a 100 μm aperture as the aperture, measuring the particle size distribution of particles of 2 to 40 μm based on the number,
Then the values according to the invention were determined.

The obtained primary fine powder is supplied to the second
10 via the primary fines feed injection feeder 202 at 33.4 kg / hr. Of the multi-stage fine powder classification means set at a classification point of 2.9 μm with the ratio of
It was introduced into a stage fines classifier 220. The introduced fine powder was classified into a primary fine powder and a secondary fine powder at a classification point of 2.9 μm.

The classified primary fine powder is collected by the cyclone 2
03, the quasi-medium powder is sent to the third quantitative feeder 210 via the quasi-medium powder supply injection feeder 221 and the collection cyclone 201, and
2 and FIG. 3 for dispersing into three types of coarse powder, medium powder and secondary fine powder utilizing the Coanda effect through the nozzle 03 and the nozzle 116. The classification point of the image area was set to 4.1 μm. It was introduced into a multi-stage classifier 101, which is a second-stage classifier that constitutes a multi-stage classifier. At the time of introduction, the suction force derived from the pressure reduction in the system by the suction pressure reduction of the collection cyclones 104, 105, and 106 communicating with the discharge ports 111, 112, and 113 and the compressed air from the injection attached to the material supply nozzle 116 are used. used.

The quasi-medium powder introduced was classified instantaneously in 0.01 seconds or less. The classified coarse powder is collected by cyclone 10
After being collected in 6, the mixture was again introduced into the pulverizer 108. The classified medium powder and secondary fine powder are collected by the collecting cyclone 10.
Collected at 5,104. Classification point is 50% partial classification efficiency
And a particle size corresponding to 50% classification diameter D _p50 (μm). A TIPLEX ultrafine powder classifier 100ATP (manufactured by Hosokawa Micron Corporation) is used as the first stage fine powder classifier, and an Elbow Jet EJ-15-3 machine (Nippon Steel Mining Co., Ltd.) is used as the second-stage fine powder classifier as a multi-divided classifier. Manufactured).

The classified medium powder had a weight average particle size of 7.2.
μm, the coefficient of variation B of the number distribution is 26.3% (particle size: 4.0
8.4% by number of particles having a particle size of 8.0 μm or less.
(Containing 10.3% by number of the above particles), and had excellent performance for toner. At this time, the ratio of the finally obtained medium powder to the total amount of the supplied pulverized raw materials (that is, the classification yield) was 79.6.
%Met. In addition, when image evaluation was performed using the obtained medium powder, there was almost no fog and the result was good.

Example 2 Using the same toner pulverization raw material as in Example 1, pulverization and classification were carried out in the same apparatus system. Collision type air crusher,
The coarse powder classifier and the second-stage fine powder classifier used the same apparatus as in Example 1, and the first-stage fine powder classifier used was Turbo Classifier TC-40 (manufactured by Nisshin Engineering).

The pulverized raw material was added at 30.0 kg / hr. And obtained a fine powder having a weight average particle size of 7.3 μm. This fine powder was supplied at 33.5 kg / hr. And the first-stage fine powder classifier whose classification point is set to 2.9 μm and the classification point (classification point between the first and second fractionation areas) is set to 4.1 μm. The mixture was introduced into a multi-stage fine classifier comprising a two-stage fine classifier (multi-segment classifier), and had a weight average particle diameter of 7.1 μm and a coefficient of variation B of the number distribution of 26.2 (particles having a particle diameter of 4.0 μm or less were 8 9. Particles containing 0.5% by number and having a particle size of 8.0 μm or more.
(Containing 8% by number) having a sharp distribution of 79.9%. In addition, when image evaluation was performed using the obtained medium powder, there was almost no fog and the result was good.

Example 3 Using the same raw material for toner pulverization as in Example 1, pulverization and classification were carried out in the same apparatus system. The impact-type airflow pulverizer used was an apparatus having the configuration shown in FIG. 6 and the same apparatus as that used in Example 2 was used for the first-stage fine-particle classifier and the second-stage fine-particle classifier. The particles were pulverized by a collision type airflow pulverizer shown in FIG. In the collision type airflow pulverizer, the collision surface has a vertical angle of 55 ° (a =
55 °) conical projection, and the inclination angle of the outer peripheral collision surface with respect to the vertical plane of the central axis of the accelerator tube is 10 ° (β = 10 °)
(Α + 2β = 75 °).

The diameter of the collision member is 100 mm (b = 1
00 mm), the distance between the end of the collision surface and the outlet of the accelerating tube is 50 mm (a = 50 mm), and the shape of the grinding chamber is 1
A 50 mm cylindrical grinding chamber (c = 25 mm) was used. The inclination of the accelerator tube in the major axis direction with respect to the vertical line is substantially zero.
° C. 39.0Kg /
hr. , And the classified coarse powder was introduced into the impingement type air current pulverizer, and the pressure was 6.0 kg.
/ Cm ² (G), pulverized using 6.0 Nm ³ / min compressed air, circulated again to the classifier, and closed circuit pulverized. As a result, a finely pulverized toner product having a weight average diameter of 7.3 μm was obtained as classified fine powder. In addition, there was no generation of fused material, and stable operation was possible.

The pulverized raw material was 39.0 kg / hr. And obtained a fine powder having a weight average particle size of 7.3 μm. This fine powder was supplied at 44.2 kg / hr. And the first-stage fine powder classifier whose classification point is set to 4.1 μm and the classification point (the classification point between the first and second fractionation areas) is set to 4.1 μm. The mixture was introduced into a multi-stage fine powder classifier comprising a two-stage fine powder classifier (multi-segment classifier), and had a weight average particle diameter of 7.0 μm and a coefficient of variation B of the number distribution of 26.1 (particles having a particle diameter of 4.0 μm or less of 8 μm). 9. Particles containing 0.5% by number and having a particle size of 8.0 μm or more.
Contains 8% by number. ) Was obtained with a classification yield of 79.8%. When the image evaluation was performed on the obtained middle powder, there was almost no fog and the result was good.

Example 4 Using the same raw material for toner pulverization as in Example 1, pulverization and classification were carried out in the same apparatus system. The apparatus of the structure shown in FIG. 9 was used for the collision-type airflow pulverizer, and the same apparatus as that of Example 2 was used for the first-stage coarse powder classifier and the second-stage fine powder classifier. The powder was pulverized by a collision type air pulverizer shown in FIG.
In the collision type airflow pulverizer, the collision surface has a vertical angle of 55 ° (a
= 55 °), and the inclination angle of the outer peripheral collision surface with respect to the vertical plane of the center axis of the accelerator tube is 10 ° (β = 10 °).
°) (α + 2β = 75 °).

The diameter of the collision member is 100 mm (b = 1
00 mm), the distance between the end of the collision surface and the outlet of the accelerating tube is 50 mm (a = 50 mm), and the shape of the grinding chamber is 1
A 50 mm cylindrical grinding chamber (c = 25 mm) was used. The inclination of the accelerator tube in the major axis direction with respect to the vertical line is substantially zero.
°, and the raw material supply port used was one that was open in the entire circumferential direction of the acceleration tube. 3 crushed raw materials with fixed quantity feeder
7.0 kg / hr. Is supplied to a forced vortex type classifier, and the classified coarse powder is introduced into the collision type air flow pulverizer, and compressed air having a pressure of 6.0 kg / cm ² (G) and 6.0 Nm ³ / min is supplied. After being crushed using the crusher, the mixture was circulated again through a classifier to perform closed-circuit crushing. As a result, a finely pulverized toner product having a weight average diameter of 7.3 μm was obtained as classified fine powder. In addition, there was no generation of fused material, and stable operation was possible.

[0095] 37.0 Kg / hr. , And a fine powder having a weight average particle size of 7.3 μm was obtained. This fine powder was 42.1 kg / hr. And the first-stage fine powder classifier whose classification point is set to 2.9 μm and the classification point (classification point between the first and second fractionation areas) is set to 4.1 μm. The mixture was introduced into a multi-stage fine classifier comprising a two-stage fine classifier (multi-segment classifier), and had a weight average particle diameter of 7.1 μm and a coefficient of variation B of the number distribution of 26.2 (particles having a particle diameter of 4.0 μm or less were 8 9. Particles containing 0.4% by number and having a particle size of 8.0 μm or more.
Contains 9% by number. ) Was obtained with a classification yield of 79.7%. When the image evaluation was performed on the obtained middle powder, there was almost no fog and the result was good.

Comparative Example 1 Using the same toner pulverization raw material as in Example 1, pulverization and classification were performed according to the flowchart of FIG. The crusher shown in FIG. 13 is used as a collision-type airflow crusher, the same apparatus as in Example 1 is used as a coarse powder classifier, and a dispersion separator DS5UR (manufactured by Nippon Pneumatic Industries, Ltd.) is used as a fine powder classifier. It was used.

The pulverized raw material was added at 18.0 kg / hr. And a coefficient of variation B of the number distribution is 31.0% (particles having a particle diameter of 4.0 μm or less are 19.2%).
12.8% by number of particles having a particle size of 8.0 μm or more. ) Was obtained with a classification yield of 54.3%. When image evaluation was performed using the obtained medium powder, fog was considerably large, and good results could not be obtained. As the impingement-type airflow pulverizer, a plane-shaped impingement surface having a shape perpendicular to the longitudinal direction of the accelerating tube was used.

The diameter of the collision member is 90 mm (b = 90 m
m), and the distance between the end of the collision surface and the outlet of the accelerator is 50 m
m (a = 50 mm), and the shortest distance from the crushing chamber wall is 2
0 mm (c = 20 mm), and the grinding chamber was box-shaped. 13.0 Kg / hr.
In a forced vortex type classifier, and the classified coarse powder is introduced into the impingement type airflow pulverizer at a pressure of 6.0 kg / cm.
² (G), pulverized using 6.0 Nm ³ / min compressed air, circulated again to the classifier, and closed circuit pulverized.
As a result, the weight average diameter was 7.0 μm as the classified fine powder.
Was obtained. The supply amount is 13 kg / hr.
When the volume average diameter of the obtained fine powder increases when the amount is increased as above, fusion of the pulverized material, aggregates and coarse particles start to occur on the collision member, and the fused material clogs the raw material inlet of the acceleration tube. There was no stable operation.

Comparative Example 2 Using the same raw material for toner pulverization as in Example 1, pulverization and classification were carried out in accordance with the flowchart of FIG. The pulverizer shown in FIG. 15 is used as the impinging airflow pulverizer, the same apparatus as in Example 1 is used as the coarse powder classifier, and the dispersion separator DS5UR (manufactured by Nippon Pneumatic Industries, Ltd.) is used as the fine powder classifier. It was used. The collision-type airflow pulverizer used had a collision surface having a conical shape with an apex angle of 160 °. The diameter of the collision member is 90 mm (b = 90 m
m), and the distance between the end of the collision surface and the outlet of the accelerator is 50 m
m (a = 50 mm), and the shortest distance from the crushing chamber wall is 2
0 mm (c = 20 mm), and the grinding chamber was box-shaped.

Using a constant-rate feeder, pulverized raw material is 18 kg / h
r. , And the classified coarse powder is introduced into the impinging airflow pulverizer at a pressure of 6.0 kg /
cm ² (G), using compressed air of 6.0 nm ³ / min, was pulverized, and circulated again classifier was performed a closed circuit pulverization. As a result, the weight average diameter of the classified fine powder is 6.
An 8 μm finely pulverized product for toner was obtained. Supply amount 18.0K
g / hr. With the increase, the weight average diameter of the obtained fine powder was increased. In addition, generation | occurrence | production of the fused material was not recognized.

The pulverized raw material was 23.0 kg / hr. Of particles having a weight average particle size of 6.8 μm and a coefficient of variation B of the number distribution of 26.4% (8.5% or less particles having a particle size of 4.0 μm or less).
(A 10.3% by number of particles having a particle size of 8.0 μm or more) was obtained at a classification yield of 61.8%. In addition, when image evaluation was performed using the obtained medium powder, fog was large and good results were not obtained.

Comparative Example 3 Using the same toner pulverizing raw material as in Example 1, pulverization and classification were performed according to the flowchart of FIG. The crusher shown in FIG. 16 was used as the impingement airflow crusher, the same apparatus as in Example 1 was used as the coarse powder classifier, and the dispersion separator DS5UR (manufactured by Nippon Pneumatic Industries, Ltd.) was used as the fine powder classifier. It was used. In the impingement type air current pulverizer, the material collision surface of the collision member is perpendicular to the axis of the acceleration tube (β = 0 °), and the material collision surface has an apex angle of 50 °.
The one provided with a conical protrusion of ° (α = 50 °) was used. The diameter of the collision member is 90 mm (b = 90 mm), and the distance between the end of the collision surface and the outlet of the acceleration tube is 50 mm (a =
50 mm) and the shortest distance from the crushing chamber wall is 20 mm
(C = 20 mm), and the grinding chamber was box-shaped.

The raw material to be pulverized is measured at 22 kg / h by a quantitative feeder.
r. , And the classified coarse powder is introduced into the impinging airflow pulverizer at a pressure of 6.0 kg /
After pulverization using a compressed air of 6.0 Nm ³ / min at ² cm (G), the mixture was circulated again to a classifier to perform closed-circuit pulverization. As a result, the classified fine powder had a weight average diameter of 6.8.
A μm toner finely pulverized product was obtained. Supply amount of 18.0Kg /
hr. With the increase, the weight average diameter of the obtained fine powder was increased. No occurrence of coarse fused matter was observed, but after one hour of operation, the collision member was inspected. As a result, it was confirmed that a layer of the fused matter of the crushed material was slightly adhered to the material collision surface.

The raw material to be crushed was 23.0 kg / hr. , A weight average particle diameter of 6.8 μm and a coefficient of variation B of the number distribution of 31.2% (particles having a particle diameter of 4.0 μm or less
12.8% by number of particles having a particle size of 8.0 μm or more. ) Was obtained with a classification yield of 51.6%. When image evaluation was performed using the obtained medium powder, fog was considerably large, and good results could not be obtained.

Example 5 100 parts by weight of an unsaturated polyester resin 4.5 parts by weight of a copper phthalocyanine pigment (CI Pigment Blue 15) 4.0 parts by weight of a charge control agent (chromium salicylate complex) 4.0 parts by weight The material was mixed with a Henschel mixer (FM-75).
After mixing well with a mold (manufactured by Mitsui Miike Kakoki Co., Ltd.)
Kneading and dispersing were performed with a twin-screw kneader (PCM-30, manufactured by Ikegai Iron Works) set to ° C. Cool the obtained kneaded material,
The resultant was coarsely pulverized to 1 mm or less by a hammer mill to obtain a coarsely crushed product for toner production.

The obtained toner pulverized raw material was pulverized and classified using the same apparatus system as in Example 1. Collision type air crusher, coarse powder classifier, first stage fine powder classifier and second
The same apparatus as in Example 1 was used for the stage fine powder classifier. 28.0 kg / hr. To obtain a fine powder having a weight average particle size of 7.2 μm.
hr. And the first-stage fine powder classifier whose classification point is set to 2.9 μm and the classification point (classification point between the first fractionation area and the second fractionation area) are set to 4.2 μm. Introduced into a multi-stage fine powder classifier comprising a two-stage fine powder classifier (multi-divider classifier), the weight average particle diameter is 7.0 μm, and the coefficient of variation B of the number distribution is 25.4% (particles having a particle diameter of 4.0 μm or less). 7.9 number%
10.2% by number of particles having a particle size of 8.0 μm or more. ) Was obtained with a classification yield of 73%. In addition, when image evaluation was performed using the obtained medium powder, there was almost no fog and the result was good.

Comparative Example 6 Using the same raw material for toner pulverization as in Example 4, pulverization and classification were carried out according to the flowchart of FIG. As a collision-type airflow pulverizer, a pulverizer shown in FIG.
kg / cm ² (G), using compressed air of 6.0 Nm ³ / min), the same coarse particle classifier as in Example 1 was used, and a dispersion separator DS5UR (Nihon New Japan) was used as a fine powder classifier. (Manufactured by Matic Industrial Co., Ltd.).

[0108] The pulverized raw material was 15.0 kg / hr. , And a fine powder having a weight average particle size of 6.7 μm was obtained. This fine powder was 20.0 kg / hr. And the first-stage fine powder classifier whose classification point is set to 4.5 μm and the classification point (classification point between the first fractionation area and the second fractionation area) is set to 2.9 μm. Introduced to a multi-stage fine powder classifier comprising a two-stage fine powder classifier (multi-divider classifier), the weight average particle diameter is 7.2 μm, and the coefficient of variation B of the number distribution is 31.0% (particles having a particle diameter of 4.0 μm or less). A medium powder having a broad particle size distribution of 20.2% by number and 12.6% by number of particles having a particle size of 8.0 μm or more was obtained with a classification yield of 51%. When image evaluation was performed on the obtained medium powder, fog was considerably large and good results were not obtained as image quality.

[0109]

According to the method for producing a toner of the present invention, a toner having a sharp particle size distribution can be obtained with high pulverization efficiency and a high classification yield, not only for toner particles existing in the world but also for the ultimate fine particles. There is an advantage that generation of fusion, aggregation, and coarsening can be prevented, wear in the apparatus due to toner components can be prevented, and continuous stable production can be performed. Further, by using the toner manufacturing method of the present invention, the image density is stable and high, the durability is good, and the fog,
An electrostatic image developing toner having an excellent predetermined particle size without defects such as poor cleaning can be obtained at low cost. Further, there is an advantage that a toner for developing an electrostatic image having a small particle diameter, particularly 3 to 8 μm, can be effectively obtained.

[0110]

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining a manufacturing method of the present invention.

FIG. 2 is a schematic diagram showing a specific example of an apparatus system for performing the manufacturing method of the present invention.

FIG. 3 is a schematic diagram showing one specific example of an apparatus system for performing the manufacturing method of the present invention.

FIG. 4 is a schematic cross-sectional view of a pulverizing apparatus which is a specific example for implementing a collision type air current pulverizing means in the present invention.

FIG. 5 is an enlarged sectional view of a grinding chamber in FIG.

FIG. 6 is a schematic sectional view of another collision-type airflow pulverizer embodying the present invention.

FIG. 7 is an enlarged sectional view taken along line AA of FIG. 6;

FIG. 8 is an enlarged sectional view taken along line BB of FIG. 6;

[0111]

FIG. 9 is a schematic sectional view of another collision-type airflow pulverizer embodying the present invention.

FIG. 10 is an enlarged sectional view taken along line CC of FIG. 9;

FIG. 11 is a schematic sectional view of a multi-divided classifier, which is a fine powder classifier at the last stage.

FIG. 12 is a flowchart for explaining a conventional manufacturing method.

FIG. 13 is a schematic sectional view showing a conventional pulverizer.

FIG. 14 is a schematic sectional view showing a conventional pulverizer.

FIG. 15 is a schematic sectional view showing a conventional pulverizer.

FIG. 16 is a schematic sectional view showing a conventional pulverizer.

[0112]

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Powder material input port 2 ... Compressed gas supply nozzle 3 ... Accelerator tube 4 ... Collision member 5 ... Discharge port 6 ... Pulverization chamber side wall 7 ... Powder material 8 ... Pulverization chamber 13 ... Accelerator tube outlet 14 Projecting central part 15 Outer peripheral collision surface 21 Accelerator tube 22 Throat part of accelerator tube

23 ... High-pressure gas ejection nozzle 24 ... Pulverized object supply port 25 ... Pulverized object supply cylinder 26 ... High-pressure gas supply port 27 ... High-pressure gas chamber 28 ... High-pressure gas introduction pipe 29 ... Acceleration Pipe outlet 30 Collision member 32 Pulverization chamber side wall 33 Pulverized material discharge port 34 Pulverization chamber 35 Laval nozzle 36 Acceleration pipe throat 37 37 Acceleration pipe outlet

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Kanda 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-6-308767 (JP, A) JP-A-6 JP-A-295098 (JP, A) JP-A-6-230606 (JP, A) JP-A-4-218065 (JP, A) JP-A-4-31873 (JP, A) JP-A-1-84259 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 9/08-9/097 B02C 19/06

Claims (2)

(57) [Claims] 1. A mixture containing at least a binder resin and a colorant is melt-kneaded, the mixture is cooled, and the cooled product is pulverized by a pulverizing means to obtain a pulverized product. Means, classified into coarse powder and fine powder, the classified coarse powder is finely pulverized by an impingement airflow pulverizing means to produce fine powder, and the generated fine powder is circulated to the coarse pulverizing and classifying means to be classified. The fine powder is introduced into a multi-stage fine powder classifying means comprising at least two or more fine powder classifying means, and a method for producing a toner for developing an electrostatic image from a medium powder having a predetermined particle size range obtained by classification. and a grinding chamber for finely grinding the acceleration tube and the object to be crushed for conveying accelerate grinding object by high pressure gas in the collision type air pulverizer means, is supplied to the accelerating tube, accelerated object to be crushed Is discharged from the acceleration tube outlet into the grinding chamber, and the opening of the outlet of the acceleration tube is opened. Facing out projecting and projecting central portion provided in the central portion
A primary ground in the <br/> projecting central portion of the collision member having a periphery collision surface portion provided on the outer periphery, the primary ground material which is primary crushed
After the secondary pulverization at the outer peripheral collision portion , the secondary pulverized secondary pulverized material was further subjected to tertiary pulverization on the side wall in the pulverization chamber, then circulated to the coarse powder classification means, and classified by the coarse powder classification means. The fine powder is a production method which is introduced into a multi-stage fine powder classification means comprising at least two or more stages of fine powder classification means and a multi-divided classification means in which the final stage fine powder classification means is fractionated into at least three, The multi-divided classifying means lowers the particle group in a curved line due to the Coanda effect, divides and collects fine powder mainly composed of particles having a predetermined particle size or less in the first fractionation region, Separately collect medium powder mainly composed of particles in a predetermined particle size range,
A manufacturing method comprising: collecting a coarse powder having a group of particles having a predetermined particle size or more as a main component in a third fractionation area; The classification point A of the fine powder classifying means constituting the multi-stage fine powder classifying means is defined by the following condition (1) Formula 1.0 <A ₁ ... <A _n-1 <5.0 (2) Formula 1.5 <A _n <7 0.0 (3) Formula A ₁ <... <A _n-1 <A _n (4) Formula 2 ≦ n ≦ 5 [The classification point A in the formula is a particle size corresponding to a partial classification efficiency of 50%; % classification diameter D _{P5 0} shows what is referred to as ([mu] m). n indicates the number of stages of the multistage fine powder classification means. Classification point of the final stage of the multi-stage fine powder classifying device is a classification point of the first fractionation zone and a second fraction region. And the weight-average diameter D _{4 of} the middle powder collected in the multi-stage fine powder classification step is 3 to 3.
8 μm, and the variation coefficient B of the number distribution is the following condition (5) Equation 20 ≦ B ≦ 40 [where B is the variation coefficient (S /
D ₁ ) × 100. Here, S indicates the standard deviation in the number distribution in the medium powder, and D ₁ indicates the number average diameter (μm) in the medium powder. ] The method for producing a toner for developing an electrostatic image according to the present invention. 2. The case where the apex angle of the central portion of the collision member projecting from the collision surface is α (°), and the inclination angle of the outer collision portion with respect to the vertical plane of the central axis of the acceleration tube is β (°). , The α
The method according to claim 1, wherein β satisfies the following formula: 0 <α <90, β> 0, 30 ≦ α + 2β ≦ 90.