JP3155855B2 - 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 process 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, high image quality of copiers and printers,
The performance required for toner as a developer has become more severe with the development of higher definition, and the particle size of the toner has become smaller, and the particle size distribution of the toner has no coarse particles and is sharp with few fine powders. Is being required.

[0004] 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. Charge control agent, and JP-A-54-4214
In the so-called one-component developing method disclosed in JP-A-55-18656, various magnetic materials for imparting transportability and the like to the toner itself are used. Agent, the fluidity imparting agent is dry-mixed, and then roll-milled, melt-kneaded in a general-purpose kneading device such as an extruder, and cooled and solidified.
The particles are pulverized by various pulverizers such as a mechanical impact pulverizer, and classified by various air classifiers, so that the particle diameter required for the toner is made uniform. If necessary, a fluidizing agent, a lubricant and the like are dry-mixed to form a toner. When the toner is used in a two-component developing method, various magnetic carriers and a toner are mixed and then used for image formation.

As described above, in order to obtain toner particles which are fine particles, the method shown in the flowchart of FIG. 16 has conventionally been generally employed.

[0006] The coarsely crushed toner is supplied to a coarse powder classifying means continuously or sequentially and classified, and the classified coarse powder having a coarse particle group of a specified particle size or more as a main component is sent to a crushing means and crushed. Circulated again to the coarse powder classification means.

[0007] The finely pulverized toner mainly composed of particles within the specified particle size range and particles smaller than the specified particle size is sent to fine powder classifying means, and the medium powder mainly composed of particles having the specified particle size is used. And a fine powder mainly composed of a group of particles having a specified particle size or less.

As the pulverizing means, various pulverizing devices 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 FIG. 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 stream, injects the powder material from an outlet of an acceleration tube, and opposes the powder material to an opening surface of an outlet of the acceleration 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 FIG. 17, 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 powder material is sucked into the acceleration tube 46 from the powder material supply port communicating with the acceleration tube 46 by the high-pressure gas supplied to the acceleration tube 46, and the powder material is ejected together with the high-pressure gas to cause collision with the collision member 43.
And crushed by the impact.

However, in the collision type air-flow crusher shown in FIG. 17, since the supply port 40 for the crushed object is provided in the middle of the acceleration tube 46, the crushed object sucked and introduced into the acceleration tube 46 is not crushed. Immediately after passing through the pulverized material supply port 40, the fluid is dispersed in the high-pressure gas flow and rapidly accelerated while changing the flow path toward the outlet of the acceleration tube by the high-pressure gas flow ejected from the high-pressure gas supply nozzle 47. In this state, the relatively coarse particles of the material to be crushed flow through the low flow portion in the acceleration tube due to the effect of the inertial force,
Relatively fine particles flow in the high-flow portion of the accelerating tube, so they are not sufficiently uniformly dispersed in the high-pressure airflow. Collision and partial collision with the member are likely to occur, so that the pulverization efficiency is likely to be reduced and the processing capacity is likely to be reduced.

In the vicinity of the collision surface 41, a portion having a high dust concentration composed of the crushed material and the crushed material is likely to be locally generated. Therefore, when the crushed material 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 material to be ground has abrasion properties, local powder wear is likely to occur on the collision member, the collision surface, and the acceleration tube,
There has been a point to be improved in terms of increasing the frequency of replacing the collision member and continuously producing it stably.

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 crushers, the local increase in the dust concentration near the collision surface can be suppressed, so that the fusion, coarsening, and agglomeration of the crushed material can be somewhat moderated, and the crushing efficiency is slightly improved. However, further improvements are desired.

For example, when a particle group having a weight average diameter of 8 μm and a coefficient of variation A of the number distribution (defined later) of 33 is obtained, a classification mechanism for removing a coarse powder region is provided. The raw material is pulverized to a predetermined average particle size by a pulverizing means such as an impinging air current 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.

Here, the weight average particle diameter is data measured using a Coulter Counter TA-II manufactured by Coulter Electronics (USA) with an aperture of 100 μm.

In such a conventional method, particularly, as the weight average particle diameter of the toner is 8 μm or less and the average weight diameter becomes smaller, the energy efficiency in the pulverizing means decreases and the classification yield in the fine powder classification means. There is a problem that this leads to a decrease in

As a method for improving the yield reduction by the fine powder classification means in the conventional method, Jiro Nakayama, Kazuhiro Yonezawa, Powder and Industry, April, p. 45 (1984), the latest ultrafine pulverization process technology, As described on page 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. By this method, the yield can be improved to some extent, but it is mainly intended to reduce the decrease in the classification accuracy and the decrease in the classification yield due to the increase in the capacity of the classification means, and further improve the classification accuracy. It is also true that improvement in the classification yield is desired.

Further, as the weight average particle diameter of the toner is 8 μm or less and the weight average particle diameter becomes smaller, the degree of aggregation of the toner particles increases, and the generation of extra fine particles increases. It tends to be difficult to remove the extremely fine particles.

As shown in FIG. 16, when the fine powder classifying means of the conventional method has one stage, the chance of removing the ultrafine particles is small once and the ultrafine particles cannot be completely removed. Jiro Nakayama and Kazuhiro Yonezawa, Powder and Industry, April, p. 45 (198
4), latest ultra-fine grinding process technology, 347 pages (198
As described in 5), when the fine powder classification means has multiple stages, the removal of the ultrafine particles is considerably improved as compared with the case of one stage. However, the image quality is not yet sufficient, and further improvement in image quality is eagerly desired. Therefore, a method for efficiently producing a toner having an extremely small number of fine particles and a weight average particle diameter of 8 μm or less has been desired.

[0020]

SUMMARY OF THE INVENTION Accordingly, 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 electrostatic images having a fine particle size distribution.

In the present invention, a mixture containing a binder resin, a colorant and an additive is melt-kneaded, and after cooling the melt-kneaded product,
It is an object of the present invention to provide a method for efficiently producing a fine particle product (used as a toner) having a predetermined particle size distribution from a group of solid particles produced by pulverization with high yield.

An object of the present invention is to provide a method for efficiently producing a toner for developing an electrostatic image having a weight average particle diameter of 3 to 8 μm (preferably 3 to 7 μm).

[0024]

The present invention achieves the above object by the following constitution.

In the present invention, a mixture containing at least a binder resin and a colorant is melt-kneaded, the kneaded product is cooled, and the cooled product is pulverized by a pulverizing means to obtain a pulverized product. The powder is classified into coarse powder and fine powder by the powder classification means, and the classified coarse powder is finely pulverized by the impingement type air current pulverization means to produce fine powder, and the generated fine powder is circulated to the coarse powder classification means and classified. The fine powder obtained is introduced into a multi-stage fine powder classifying means having at least two or more fine powder classifying means, and an electrostatic charge image for producing a toner for developing an electrostatic charge image from a powder having a medium particle size within a predetermined particle size obtained by classification. In the method for producing a developing toner, the collision-type airflow pulverizing means has an accelerating tube for conveying and accelerating coarse powder supplied by a high-pressure gas, and a pulverizing chamber for finely pulverizing the coarse powder; At the rear end of the accelerating tube, coarse powder is supplied to supply coarse powder into the accelerating tube. A crushing member having a collision surface provided opposite to an opening surface of the outlet of the acceleration tube in the crushing chamber; a crushed material of coarse powder crushed by the colliding member; the has side walls for further pulverized by the collision, the closest distance 1 ₁ between the edge of the side wall and the collision member is nearest the grinding chamber front wall facing the impact surface and the edge of the collision member distance 1 shorter than _2, in the pulverizing chamber, after further grinding the ground product of the milling and coarse coarse powder in the collision surface and the side wall of the impact member, and circulated to the coarse powder classifier means, the coarse powder classifier means The fine powder classified in the above is introduced into a multi-stage fine powder classifying means having at least two or more fine powder classifying means, and a fine powder mainly composed of a particle group having a predetermined particle size or less and a particle group having a predetermined particle size range are mainly used. For developing electrostatic images having a multi-stage fine powder classification process for classifying and collecting medium powder as a component A method of manufacturing a chromatography, classification point A of a multi-stage fine powder classifying means following conditions (1)
To (4) 1.0 (μ) <A _n-1 <5.0 (μ) (1) 1.5 (μ) <A _n <7.0 (μ) (2) _An-1 <A _n (3) 2 ≦ n ≦ 5 (4) (wherein the classification point A is a particle diameter corresponding to a partial classification efficiency of 50% and is called a 50% classification diameter D _p50 (μm). N indicates the number of stages of the fine powder classification means constituting the multi-stage fine powder classification means, and the classification point of the first stage of the multi-stage fine powder classification means is A
_1, the second stage of classification points A _2, n-th stage is defined as A _n. ), And the weight-average particle diameter (D ₄ ) is 3 to 8 μm, and the variation coefficient B of the number distribution is the following condition (5) 20 ≦ B ≦ 40 (5) (where, B is a coefficient of variation (S /
D ₁ ) × 100, where S indicates a standard deviation in the number distribution of the intermediate powder, and D ₁ indicates a number average particle size (μm) in the intermediate powder. The present invention relates to a method for producing a toner for developing an electrostatic charge image, characterized by satisfying the condition (1).

Hereinafter, the present invention will be specifically described with reference to the accompanying drawings.

FIG. 1 is an example of a flowchart showing the 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, pulverized, and after pulverization, introduced into the coarse powder classifying means.

A predetermined amount of fine powder is supplied to a multi-stage fine powder classification means comprising at least two or more stages of fine powder classification means and classified into fine powder and medium powder.

The classified medium powder is used as a toner as it is, 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 the classification and pulverization conditions, the weight average particle diameter is 3 to 8 μm (preferably 3 to 7 μm), and the coefficient of variation B of the number distribution is 20 to 40. It is possible to efficiently generate a toner having a small particle size. FIG. 2 shows an example of the device system of the present invention.

In this apparatus system, the pulverized raw material serving as the toner powder raw material is introduced into the coarse powder classifier 109 via the first quantitative feeder 102, and the classified primary fine powder is supplied via the collection cyclone 107. Is sent to the second fixed quantity feeder 110 and the primary fine powder supply injection feeder 1
Introduced into the first-stage fines classifier 101 via 16.
The coarse powder classified by the coarse powder classifier 109 is sent to the pulverizer 108, pulverized, and then re-introduced into the coarse powder classifier 109 together with the newly input pulverized raw material. First
The primary fine powder introduced into the stage fine powder classifier 101 is classified into primary fine powder and secondary fine powder, and the primary fine powder is collected by the collecting cyclone 106. The secondary fine powder is introduced into the second-stage fine powder classifier 161 via the secondary fine powder supply injection feeder 160. The secondary fine powder introduced into the second-stage fine powder classifier 161 is classified into a secondary fine powder and a medium powder, and collected by the collecting cyclones 104 and 105, respectively.

As a pulverizing means used in the present invention, for example, a collision type air flow pulverizer of the type shown in FIGS. 3 to 8 is exemplified.

In FIG. 3, the object 80 supplied from the object supply pipe 5 is supplied to the accelerating tube 1 through the accelerating tube throat 2.
Is supplied to the accelerating tube 1 from a pulverized material supply port 4 (also a throat portion) formed between the inner wall of the nozzle and the outer wall of the high-pressure gas ejection nozzle 3.

It is preferable that the center axis of the high-pressure gas ejection nozzle 3 and the center axis of the acceleration tube 1 are substantially coaxial.

On the other hand, the high-pressure gas is introduced from the high-pressure gas supply port 6, passes through the high-pressure gas chamber 7, preferably through a plurality of high-pressure gas introduction pipes 8, and from the high-pressure gas ejection nozzle 3 toward the acceleration pipe outlet 9. Spouts while expanding rapidly toward. At this time, due to the ejector effect generated in the vicinity of the accelerating tube throat section 2, the crushed object 80 is
While being entrained by the gas coexisting with 0, it is rapidly accelerated from the pulverized material supply port 4 toward the direction of the acceleration pipe outlet 9 while being uniformly mixed with the high-pressure gas in the acceleration pipe throat section 2. Collision surface 16 of collision member 10 facing
Then, the particles collide in a state of a uniform solid-gas mixed flow without unevenness of dust concentration. Since the impact force generated at the time of collision is given to the sufficiently dispersed individual particles (objects to be crushed 80), very efficient crushing can be performed.

The pulverized material pulverized on the collision surface 16 of the collision member 10 further secondary-collides (or tertiary-collides) with the side wall 14 of the pulverizing chamber 12, and the pulverized material disposed behind the collision member 10 It is discharged from the discharge port 13.

The collision surface 16 of the collision member 10 has a cone shape as shown in FIG. 3, or a collision shape as shown in FIGS.
The fact that the collision surface 16 is a collision surface having a conical projection makes the dispersion of the pulverized material in the pulverization chamber 12 uniform,
This is preferable in that the secondary collision with the side wall 14 is efficiently performed. Further, when the pulverized material discharge port 13 is located behind the collision member 10, the pulverized material can be smoothly discharged.

FIG. 4 shows an enlarged view of the grinding chamber. 4, the closest distance 1 ₁ between the edge 15 and the side wall 14 of the collision member 10 may be shorter than the closest distance 1 ₂ between the front wall 17 and the edge 15 of the impact member 10, the acceleration This is important in order not to increase the powder concentration in the grinding chamber near the pipe outlet 9. Furthermore, since the closest distance 1 ₁ is shorter than the closest distance 1 ₂ ,
The secondary collision of the pulverized material on the side wall can be efficiently performed. Further, the collision member 10 is 9
Slope θ ₁ smaller than 0 ° (more preferably, 55 °
87.5 °, more preferably an inclination θ of 60 ° to 85 °
It is preferable to have the slope having the condition ₁ ) as the collision surface in order to uniformly disperse the pulverized material and efficiently perform the secondary collision on the side wall 14.

As shown in FIG. 17, the collision surface 41 is
In contrast to a crusher that is a 90-degree flat collision member, a crusher having an inclined collision surface, when crushing a resin or a sticky substance, fuses and agglomerates the material to be crushed. In addition, coarsening hardly occurs, and pulverization at a high dust concentration becomes possible. In addition, in the case of the abraded material to be crushed, wear generated on the inner wall of the accelerating tube and the collision surface of the collision member is not locally concentrated, so that the life can be extended and stable operation can be performed.

Also, if the inclination of the acceleration tube 1 in the long axis direction is preferably within a range of 0 to 45 ° with respect to the vertical direction, the crushed object 80 is closed at the crushed object supply port 4. And can be processed.

In the case where the material to be ground has poor fluidity, when the material to be ground has a cone-shaped member below the supply pipe 5, although the amount is small, the material tends to stay at the lower part of the cone-shaped member, and the material is accelerated. The inclination of the pipe 1 is 0 to 2 with respect to the vertical direction.
Within the range of 0 ° (more preferably 0 to 5 °), there is no stagnation of the material to be ground in the lower cone portion, and the material to be ground can be smoothly supplied to the acceleration tube.

FIG. 5 is a sectional view taken along the line AA 'in FIG. It is understood from FIG. 5 that the material to be ground 80 is smoothly supplied to the acceleration tube 1.

[0043] intersects the extension at right angles with the acceleration tube central axis, the distance 1 ₂ between the outermost peripheral edge portion 15 of the impact surface 16 of the collision member 10 to the surface facing the accelerating tube outlet 9, 0 diameter of the collision member 10 A range of 2 to 2.5 times is preferable for grinding efficiency,
It is better if it is in the range of 0.4 times to 1.0 times.

If the distance 1 ₂ is less than 0.2 times, the collision surface 16
The dust concentration in the vicinity may be abnormally high,
If it exceeds 2.5 times, the impact force is weakened, and as a result,
Pulverized material tends to decrease.

The outermost peripheral end 15 and the side wall 14 of the collision member 10
The shortest distance 1 ₁ between the range of 0.1 times the diameter of the impact member 10 twice is preferable.

When the pressure is less than 0.1 times, the pressure loss at the time of passage of the high pressure gas is large, the pulverization efficiency tends to decrease, and the flow state of the pulverized material tends not to be smooth. The effect of the secondary collision of the object to be crushed on the indoor wall 14 is reduced, and the crushing efficiency tends to be reduced.

More specifically, the length of the accelerating tube is 50 to
Preferably, the diameter of the collision member 10 is 30 to 3 mm.
Preferably it has a diameter of 00 mm.

Further, it is preferable that the collision surface 16 and the side wall 14 of the collision member 10 are formed of ceramic from the viewpoint of durability.

FIG. 6 is a sectional view taken along line BB 'in FIG. In FIG. 6, the distribution state of the crushed object in the vertical plane with respect to the vertical direction of the crushed object supply port 4 passing through the crushed object supply port 4 is such that the greater the inclination of the acceleration tube 1 with respect to the vertical direction, the more the distribution state. Because of the bias, the smaller the slope, the more uniform the distribution. The best inclination of the accelerating tube 1 in the range of 0 to 5 ° was confirmed by changing the accelerating tube 1 to a transparent acrylic resin accelerating tube for internal observation.

FIG. 7 is a sectional view taken along the line CC 'in FIG. In FIG. 7, the pulverized material is discharged backward through the pulverizing chamber 12 between the collision member support 11 and the side wall 14.

FIG. 8 is a sectional view taken along the line DD 'in FIG. In FIG. 8, two high-pressure gas introduction pipes 8 are provided, but depending on the case, the number of high-pressure gas introduction pipes 8 may be one or three or more.

FIGS. 9 to 11 are schematic views showing other specific examples of the impingement type air current pulverizer of the present invention.

In FIG. 9, the same numbers as those in FIG. 3 indicate the same members.

In the collision-type air-flow crusher shown in FIG. 9, the inclination of the acceleration tube 1 in the major axis direction is preferably 0 to 45 ° (more preferably 0 to 20 °, more preferably 0 to 20 °) with respect to the vertical line. 5 °), the crushed object 80 is supplied to the acceleration tube 1 from the crushed object supply port 20 passing through the accelerating tube throat section 4. Compressed gas such as compressed air is introduced into the accelerating tube 1 from the inner wall of the throat portion and the outer wall of the crushed material supply port, and the crushed material 80 supplied to the accelerating tube 1 is instantaneously accelerated to a high speed. Will have. And
The crushed object 80 ejected from the acceleration pipe outlet 9 into the crushing chamber 12 at a high speed collides with the collision surface 16 of the collision member 10 and is crushed.

An object 80 to be crushed is charged from the center of the throat 4 of the acceleration tube 1 and the object 80 to be crushed in the acceleration tube 1 is dispersed.
By uniformly jetting the object 80 to be crushed from the acceleration tube outlet 9 and efficiently colliding with the colliding surface 16 of the opposing colliding member 10, the crushing efficiency can be improved as compared with the related art.

The collision surface 16 of the collision member 10 is
14 and FIG. 14 and FIG. 15, the shape having conical projections on the collision surface also results in good dispersion after collision and fusion, aggregation, Abrasion does not occur, crushing at high dust concentration is possible, and wear generated on the inner wall of the accelerating tube and the collision surface of the collision member is locally concentrated on the crushed material with abrasion. And a stable operation is possible.

FIG. 10 is a sectional view taken along the line GG 'in FIG. The crushed object 80 is supplied from the crushed object supply nozzle 20 to the acceleration tube 1, and the high-pressure gas is supplied to the acceleration tube 1 through the throat portion 4.

FIG. 11 is a sectional view taken along the line HH 'in FIG. As long as the inclination of the acceleration tube 1 in the long axis direction is in the range of 0 to 45 °, as in the pulverizer shown in FIG.
Can be processed without clogging at the supply port 20 of the material to be crushed, but the material having poor fluidity of the material to be crushed 80 tends to stay at the lower part of the supply pipe 5 for the material to be crushed, As 0 to 20 ° (more preferably 0 to 5 °)
Within the range, the object 80 is smoothly supplied into the acceleration tube 1 without stagnation of the object 80.

When the crusher shown in FIG. 3 is compared with the crusher shown in FIG. 9, the crusher shown in FIG.
0 was satisfactorily dispersed and supplied into the acceleration tube, so that the pulverization efficiency was good.

An air current classifier is used as a coarse pulverizing classifier used in the present invention. For example, a DS classifier manufactured by Nippon Pneumatic Industrial Co., Ltd., a micron separator manufactured by Hosokawa Micron Co., Ltd., and the like can be used.

Preferably, an air flow classifier shown in FIGS. 12 and 13 is used to improve the classification accuracy of fine powder and coarse powder.

In FIG. 12, 36 denotes a cylindrical main body casing, 31 denotes a lower casing, and a hopper 32 for discharging coarse powder is connected to a lower portion thereof. A classifying chamber 28 is formed inside the main body casing 36. An upper part of the classifying chamber 28 has an annular guide chamber 26 attached to an upper part of the main body casing 36 and a conical (umbrella-shaped) upper part whose central part is higher. It is closed by a cover 25.

A plurality of introduction louvers 27 arranged in the circumferential direction are provided on a partition wall between the classifying chamber 28 and the guide chamber 26, and the powder material and the air sent into the guide chamber 26 are supplied from between the introduction louvers 27. It is swirled into the classifying chamber 28 to flow therethrough. It is preferable that the air and the powder material flowing in the guide chamber 26 through the supply tube 24 be uniformly distributed to the introduction louvers 27 in order to accurately classify. Introduction louver 2
It is necessary that the flow path until reaching 7 has a shape in which concentration due to centrifugal force is unlikely to occur. In this embodiment, the supply pipe 24 is connected from the upper direction perpendicular to the horizontal plane of the classification chamber 28. It is not limited to this.

In this way, the air and the pulverized material are supplied to the classifying chamber 28 through the introduction louver 27, and when the air and the pulverized material are supplied to the classification chamber 28 through the introduction louver 27, the dispersion is significantly improved as compared with the conventional method. Is obtained. Further, the introduction louver 27 is movable, and the introduction louver interval can be adjusted.

A classifying louver 37 arranged in the circumferential direction is provided below the main body casing 36, and the classifying chamber 28 is externally provided.
The classification air that generates a swirling flow is introduced through a classification louver 37.

At the bottom of the classifying chamber 28, a conical (umbrella-shaped) classifying plate 29 whose central part is high is provided, and a coarse powder discharge port 38 is formed around the outside of the classifying plate 29. A fine powder discharge pipe 30 having a fine powder discharge port 81 is connected to the center of the classifying plate 29, and the lower end of the fine powder discharge pipe 30 is bent into an L-shape. It is located outside the side wall. Further, the fine powder discharge pipe 30 is connected to a suction fan 34 via a fine powder collecting means 33 such as a cyclone or a dust collector, and the suction fan 34 applies a suction force to the classifying chamber 28, and the classification louver 37 The swirling flow required for classification is caused by the suction air flowing into the classification chamber 28 from between.

The air flow classifier preferably used as the coarse powder classifying means has the above-mentioned structure, and is used for pulverizing the powder material pulverized by the above-mentioned impingement type air flow pulverizer into the guide chamber 26 through the supply pipe 24. When air containing air and a powder material containing a newly supplied pulverized raw material is supplied, the air containing this powder material passes between the guide chambers 26 and between the introduction louvers 27 and turns into the classifying chamber 28. It flows in while being dispersed at a uniform concentration.

The powder material that has swirled into the classifying chamber 28 is swirled by a suction fan 34 connected to the fine powder discharge pipe 30 along a suction air flow flowing from between the classifying louvers 37 below the classifying chamber. The coarse powder which is centrifuged into coarse powder and fine powder by the centrifugal force acting on each particle, and which circulates around the outer circumference in the classification chamber 28 is discharged from the coarse powder discharge port 38 and discharged from the lower hopper 32. Is supplied to the supply pipe 5. The fine powder moving to the center along the upper inclined surface of the classification plate 29 is discharged to the fine powder collection means 33 by the fine powder discharge pipe 30 and then introduced into the multi-stage fine powder classification means.

Since the air flowing into the classifying chamber 28 together with the powder material flows in a swirling flow, the velocity of the particles swirling in the classifying chamber 28 toward the center becomes relatively smaller than the centrifugal force. In the chamber 28, particles having a small particle diameter are satisfactorily classified, and fine powder having a very small particle diameter can be efficiently discharged to the fine powder discharge pipe 30. Moreover, since the powder material flows into the classifying chamber at a substantially uniform concentration, it can be obtained as a powder having a fine distribution.

FIG. 13 is a sectional view taken along the line KK 'in FIG.

By using the airflow classifier shown in FIG. 12 in combination with the above-mentioned impingement airflow pulverizer, the mixing of fine powder into the pulverizer can be suppressed or prevented well, and excessive pulverization of the pulverized material can be prevented. In addition, the classified coarse powder is smoothly supplied to the pulverizer, and further uniformly dispersed in the accelerating tube, and is pulverized well in the pulverizing chamber, thereby improving the yield of the pulverized material and the energy efficiency per unit weight. be able to.

As the fine powder classifying means constituting the multi-stage fine powder classifying means used in the present invention, an air flow classifier is preferably used. For example, DS classifier manufactured by Nippon Pneumatic Co., Ltd., micron separator manufactured by Hosokawa Micron, AT
Examples include a P-type classifier and a turbo classifier manufactured by Nisshin Engineering.

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. Good.

When the number of stages of the fine powder classifying means constituting the multi-stage fine powder classifying means is one, that is, in the case of one-stage classification, there is little chance of removing ultra-fine particles (the number of times), so that the image quality is deteriorated, especially the fog Had been reduced. In particular, in a region where the weight average diameter of the toner is 8 μm or less, this tendency is more remarkable as the weight average diameter becomes smaller. When the number of fine powder classification means in the multi-stage fine powder classification step is more than five, the image quality (especially, fogging property) is good, but the apparatus cost increases.
It is not preferable because the manufacturing cost increases accordingly.

The combination of the classifiers as the fine powder classifying means constituting the multi-stage fine powder classifying means may be either a combination of the same model or a combination of different models.

As a result of intensive studies, the classification conditions of the fine powder classifying means constituting the multi-stage fine powder classifying means are determined by setting the classification conditions so that the following conditions (1) to (4) are satisfied. Extremely high particle removal efficiency,
In addition, it has been found that the classification yield is favorably improved.
Therefore, in order to efficiently remove the ultrafine particles and to improve the image quality (especially fog) and the classification yield more favorably, the classification point A of the fine powder classification means constituting the multi-stage fine powder classification means is as follows: It is preferable to set the following conditions (1) to (4).

When the following condition (3) satisfies A _n-1 > _An , the efficiency of removing ultrafine particles is good, but the classification yield is undesirably low.

1.0 (μ) <A _n-1 <5.0 (μ) (1) 1.5 (μ) <A _n <7.0 (μ) (2) A _n-1 < A _n (3) 2 ≦ n ≦ 5 (4) [The classification point A in the formula is a particle diameter corresponding to a partial classification efficiency of 50%, and is called a 50% classification diameter D _p50 (μm). Value. The partial classification efficiency was determined by the following equation (A).

[0079]

[Outside 1] D _i : i-th particle size R _c (D _i ): cumulative particle size distribution of coarse powder after classification _Ro (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 volume cumulative particle size distribution measured using a Coulter Counter TA-II manufactured by Coulter Electronics Co., Ltd. (USA) with an aperture of 100 μm.

N represents the number of stages of the fine powder classifying means constituting the multi-stage fine powder classifying means. The first class of the multi-stage fine powder classifying means is A ₁ , the second class is A ₂ , and the n-th class is The point is A _n
Is defined. The classification point may be set to an optimum condition depending on the particle size of the pulverized raw material, the desired medium powder particle size, the true specific gravity of the powder, and the like.

In the present invention, the pulverizing step shown in the flow chart of FIG. 1 is not limited to this. For example, one coarse pulverizing means and one coarse pulverizing means may be used. There may be two or more means. What kind of combination constitutes the pulverizing step may be appropriately set depending on a desired particle diameter, a constituent material of the 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 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 smaller 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 pulverization means and the classification yield in the fine powder classification means. Further, as the weight average particle size of the toner becomes smaller,
Since the degree of aggregation of the toner particles is increased and the generation of extra fine particles is increased, the extra fine particles generated by the pulverizing means cannot be completely removed by the fine powder classifying means, resulting in a decrease in image quality (particularly a decrease in fogging). Was.

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. However, the reduction in classification accuracy mainly due to an increase in the capacity of the classification means has been attempted. The purpose of this method is to reduce the decrease in the classification yield, and this method can improve the classification yield to a certain extent, but also has a one-stage fine powder classification means with regard to the removal efficiency of ultrafine particles. Although improved, the image quality was still not sufficient, and the image quality (especially, fogging) was not satisfactory.

The method of the present invention uses a highly efficient grinding means
Extremely energy efficient toner raw material can be ground,
Good production cost reduction in the pulverizing process can be achieved. 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) can be obtained. Moreover, the removal efficiency of the ultrafine particles can be extremely increased.

The synergistic effect of the high-efficiency pulverizing means and the multi-stage fine-powder classifying means having a controlled classification point allows the production cost to be reduced.
In addition, it is possible to manufacture a toner having extremely small amount of ultrafine particles and excellent image quality (especially, fogging property).

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 sufficiently mixing with a mixer such as a heating roll, a kneader, an extruder, the pigment or dye is dispersed or dissolved in a resin mixed with each other by melting, kneading and kneading using a hot kneader. The toner can be obtained by pulverizing and classifying after cooling and solidification.

In the pulverizing step and the classifying step, the production method of the present invention is used.

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 an oil applying device is used as the binder resin used for the toner, the following toner binder resins can be used. is there.

For example, a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene and a substituted product thereof; a styrene-p-chlorostyrene copolymer, a styrene-vinyltoluene copolymer, a 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 Copolymers: polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin , Xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin and the like can be used.

In the heat and pressure fixing method or the heat and pressure roller fixing method in which little or no oil is applied, a so-called offset phenomenon 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. The physical properties of the binder resin in the toner are most significantly involved in these phenomena. However, according to the study of the present inventors, when 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 a heat and pressure roller fixing method in which almost no oil is applied, selection of a binder resin is more important. Preferred binders include crosslinked styrenic copolymers or crosslinked 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. Monocarboxylic acid having a bond or a substituted product thereof; for example, dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like; and substituted products thereof; for example, vinyl chloride, vinyl acetate, Vinyl esters such as vinyl benzoate; ethylene-based olefins such as ethylene, propylene, butylene; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone; vinyl methyl ether Vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether; vinyl monomers are 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 Glycol dimethacrylate,
Carboxylic acid esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; 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. For example, polyethylene, polypropylene, 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.

It is preferable that a charge control agent is mixed (internally added) to the toner particles for use in the toner. The charge control agent makes it possible to control the optimal charge amount 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, and by using the charge control agent The function separation and the complementarity for higher image quality for each particle size range described above can be further clarified. As the positive charge control agent,
Modified products such as nigrosine and fatty acid metal salts; and quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate may be used alone or in combination of two or more. it can. Among these, charge control agents such as nigrosine compounds and quaternary ammonium salts are particularly preferably used.

Further, the general formula

[0099]

[Outside 2] R ₁ : H, CH ₃ R ₂ , R ₃ : 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 And a copolymer with a polymerizable monomer such as methacrylic acid ester can be used as a positive charge control agent. In this case, these charge control agents can also act as (all or part of) the binder resin. Have.

As the negative charge control agent, for example, an organometallic complex and a chelate compound are effective, and examples thereof include aluminum acetylacetonate, iron (II) acetylacetonate, chromium or zinc 3,5-ditert-butylsalicylate. Among them, acetylacetone metal complexes, salicylic acid-based metal complexes or salts are preferred, and salicylic acid-based metal complexes or salicylic acid-based metal salts are particularly preferred.

The above-mentioned charge control agent (having no function 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 a magnetic toner, the magnetic material contained in the magnetic toner includes iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite;
Metals such as iron, cobalt, nickel or these metals and aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth,
Cadmium, calcium, manganese, selenium, titanium,
Alloys with metals such as tungsten and vanadium, and mixtures thereof, and the like can be given.

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 from 60 to 110 parts by weight, preferably from 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, preferably 0.5 to 20 parts by weight, based on 100 parts of the binder resin,
Further, in order to improve the transparency of the OHP film on which the toner image is fixed, the amount is preferably 12 parts by weight or less, more preferably 0.5 to 9 parts by weight.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0107]

EXAMPLES Example 1 100 parts by weight of styrene-butyl acrylate-divinylbenzene copolymer (weight ratio of monomer polymerization: 80.0 / 19.0 / 1.0, weight average molecular weight Mw: 350,000) Magnetic iron oxide (Average particle size 0.18 μm) 100 parts by weight Nigrosine 2 parts by weight Low-molecular-weight ethylene-propylene copolymer 4 parts by weight The above formulation was mixed with a Henschel mixer (FM-75).
The mixture was well mixed with a mold and a Mitsui Miike Koki Co., Ltd.), and then kneaded with a twin-screw kneader (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) set at a temperature of 150 ° C. 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 pulverizer 108 uses an apparatus having the structure shown in FIG. 3 and has a tilt in the major axis direction of the acceleration tube with respect to the vertical line (hereinafter referred to as the acceleration tube inclination) of about 0 ° (that is, the acceleration tube inclination). The collision member is a conical member having a conical shape with an apex angle of 160 ° and an outer diameter (diameter) of 100 mm, and the exit surface of the acceleration tube crossing the acceleration tube central axis at right angles. the shortest distance 1 ₂ between the outermost edge of the impact surface of the opposing impinging member and
Is 50 mm, and the shape of the crushing chamber is 150 mm in inner diameter.
Was used. Therefore, the shortest distance 1 ₁ is a 25mm. As the coarse powder classifier 109, a classifier having a configuration shown in FIG. 12 was used.

The first-stage fine-powder classifier and the second-stage fine-powder classifier may be used as a TIPLEX ultrafine classifier 200.
ATP (manufactured by Hosokawa Micron Corporation) was used.

The ground material is supplied to the airflow classifier through the supply pipe 24 by the injection feeder at a rate of 28 kg / H by the table type first fixed-quantity feeder 102, and the classified coarse powder is separated into a coarse powder discharge hopper. 32, the pressure supplied from the supply pipe 5 of the object to be pulverized is 6.0.
kg / cm ² (G), pulverized using compressed air of 6.0 Nm ³ / min, and then circulated again to the airflow classifier while being mixed with the pulverized raw material supplied at the raw material introduction section. Then, closed-circuit pulverization was performed, and the classified primary fine powder was collected by the cyclone 107 while being entrained by the suction air from the exhaust fan, and introduced into the second quantitative feeder 110. At this time, the fine powder had a weight average diameter of 6.8 μm, and had a sharp particle size distribution substantially not containing 16.0 μm or more.

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

As a measuring device, Coulter Counter T
An interface (manufactured by Nikkaki) that outputs the number distribution and volume distribution using A-II type (manufactured by Coulter) and CX
-1 Connect a personal computer (Canon),
As the electrolytic solution, a 1% NaCl aqueous solution is prepared using primary sodium chloride. The measuring method is 100 to 100
In 150 ml, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the Coulter Counter TA-II was used to form particles of 2 to 40 μ on the basis of the number, using a 100 μ aperture as an aperture. The particle size distribution was measured, and values such as the weight average particle size and the number average particle size were determined therefrom.

The obtained primary fine powder is supplied to the second quantitative feeder 1
10 through the primary fine powder supply injection feeder 116 at a classification point of 2.9 μ at a rate of 28 kg / H.
It was introduced into the first-stage fine-particle classifier 101 constituting the multi-stage fine-particle classification means set to m. The introduced primary fine powder was classified into a primary fine powder and a secondary fine powder at a classification point of 2.9 μm.

Collecting the classified primary fine powder Cyclone 1
The secondary fine powder is collected at step 06 and the second-stage fine powder classifier 161 constituting a multi-stage fine powder classifying means set to a classification point of 4.1 μm via the secondary fine powder supply injection feeder 160.
Was introduced. The introduced secondary fine powder has a classification point of 4.1 μm.
And classified into secondary fine powder and medium powder.

The classified secondary fine powder and medium powder were collected by the collecting cyclones 104 and 106, respectively.

The classification point indicates a particle diameter corresponding to a partial classification efficiency of 50% and a particle diameter called 50% classification diameter D _p50 (μm). The classified medium powder has a weight average particle diameter of 7.2 μm and a coefficient of variation B of the number distribution of 26.3% (8.6% by number of particles having a particle diameter of 4.0 μm or less, and a particle diameter of 8.0 μm). (10.8% by number of the above particles are contained.), And 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 71%. In addition, when the image evaluation was performed on the obtained medium powder, there was almost no fog, and a good result was obtained as the image quality.

(Example 2) Using the same toner pulverization raw material as in Example 1, pulverization and classification were performed by the same apparatus system.

The same type of apparatus as in Example 1 was used for the impingement type airflow crusher and coarse powder classifier, and the first-stage fine powder classifier and the second-stage fine powder classifier were Turbo Classifier TC-40 (Nissin Engineering Co., Ltd.) Manufactured).

The raw material is supplied at a rate of 28 kg / h,
A primary fine powder having a weight average particle size of 6.7 μm was obtained, and a first-stage fine powder classifier in which the classification point was set to 2.9 μm at a rate of 28 kg / h of the primary fine powder was 4.2 μm. Into a multi-stage fine-powder classification means comprising a second-stage fine-powder classifier, which has a weight average particle size of 7.1 μm and a coefficient of variation in number distribution of 26.1% (particles having a particle size of 4.0 μm or less .5 number%
9.9% by number of particles having a particle size of 8.0 μm or more. ) And excellent performance for toner.

At this time, the ratio of the finally obtained medium powder to the total amount of the pulverized raw materials charged (that is, the classification yield) was 72%.

When the image evaluation of the obtained intermediate powder was performed, there was almost no fog, and a good result was obtained as the image quality.

Example 3 Using the same raw material for toner pulverization as in Example 1, pulverization and classification were carried out using the same apparatus system.

The same apparatus as in Example 1 was used for the impingement type air current pulverizer, coarse powder classifier, first stage fine powder classifier and second stage fine powder classifier.

The raw material is supplied at a rate of 22 kg / h,
A primary fine powder having a weight average particle size of 5.8 μm was obtained. The primary fine powder was mixed at a rate of 22 kg / h with a first-stage fine powder classifier having a classification point of 2.5 μm and a classification point of 3 μm. Introduced into a multi-stage fine powder classifying means comprising a second-stage fine powder classifier set at 0.5 μm, a weight average particle diameter of 6.1 μm, and a number distribution coefficient of variation B of 23.0% (particle diameter of 4.0 μm or less). 9.8 particles
Particles having a particle size of 8.0 μm or more containing 1.1% by number
contains. ) And 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 58%. In addition, when the image evaluation was performed on the obtained medium powder, there was almost no fog, and a good result was obtained as the image quality.

Example 4 100 parts by weight of unsaturated polyester resin 4.5 parts by weight of copper phthalocyanine pigment (CI Pigment Blue 15) 4.0 parts by weight of charge control agent (chromium salicylate complex)

The ingredients of the above formulation were mixed with a Henschel mixer (F
M-75, mixed well with Mitsui Miike Kakoki Co., Ltd.), and then a twin-screw kneader (PCM-30) set to a temperature of 100 ° C.
Kneading and dispersing with a mold (Ikegai Iron Works Co., Ltd.). 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 using the same apparatus system as in Example 1.

The same apparatus as in Example 1 was used for an impinging airflow pulverizer, a coarse powder classifier, a first stage fine powder classifier and a second stage fine powder classifier.

The raw material is supplied at a rate of 25 kg / h,
A primary fine powder having an average weight particle size of 6.7 μm was obtained. A first-stage fine powder classifier having a classification point of 2.9 μm at a rate of 25 kg / h of the primary fine powder and a classification point of 4.2 μm. Introduced into a multi-stage fine powder classification means comprising a second-stage fine powder classifier, which has a weight average particle size of 7.1 μm and a number distribution variation coefficient B
Is 25.9% (including 8.0% by number of particles having a particle size of 4.0 μm or less and 10.2% by number of particles having a particle size of 8.0 μm or more).
contains. ) And 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 66%. In addition, when the image evaluation was performed on the obtained medium powder, there was almost no fog, and a good result was obtained as the image quality.

Example 5 Using the same raw material for toner pulverization as in Example 4, pulverization and classification were carried out using the same apparatus system.

The same apparatus as in Example 1 was used for the impingement type air current pulverizer, coarse powder classifier, first-stage fine powder classifier and second-stage fine powder classifier.

The raw material is supplied at a rate of 17 kg / h,
A primary fine powder having a weight average particle size of 5.7 μm was obtained, and the primary fine powder was classified at a rate of 17 kg / h in a first-stage fine powder classifier having a classification point of 2.6 μm and a classification point of 3. Introduced to a multi-stage fine powder classifier comprising a second-stage fine powder classifier set to 6 μm, the weight average particle diameter is 6.0 μm, and the coefficient of variation B of the number distribution is 23.1% (particles having a particle diameter of 4.0 μm or less). 9.9% by number, and 1.1% by number of particles having a particle size of 8.0 μm or more.
contains. ) And 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 53%. In addition, when the image evaluation was performed on the obtained medium powder, there was almost no fog, and a good result was obtained as the image quality.

(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.

A crusher shown in FIG. 17 (pressure 6.0 kg / cm ² (G), 6.0 Nm ³ /
min compressed air) and the same apparatus as in Example 1 was used as a coarse powder classifier, and a dispersion separator DS5UR (manufactured by Nippon Pneumatic Industries, Ltd.) was used as a fine powder classifier.

The pulverized raw material was supplied at a rate of 13 kg / H,
Weight average particle size 6.8 μm, variation coefficient B of number distribution is 3
0.8% (19.5% by number of particles having a particle size of 4.0 μm or less
12.5% by number of particles having a particle size of 8.0 μm or more. ) Was obtained with a classification yield of 55%. When image evaluation was performed on the obtained medium powder, fog was considerably large, and good results were not obtained as image quality.

(Comparative Example 2) Using the same toner pulverization raw material as in Example 1, pulverization and classification were performed by the same apparatus system.

The same apparatus as that used in Example 1 was used for the impingement type air current pulverizer, coarse powder classifier, first-stage fine powder classifier, and second-stage fine powder classifier.

The pulverized raw material is supplied at a rate of 28 kg / h,
A primary fine powder having a weight average particle diameter of 6.8 μm was obtained. The primary fine powder was mixed at a rate of 28 kg / h with a first-stage fine powder classifier having a classification point of 4.6 μm and a classification point of 2 μm. Introduced to a multi-stage fine powder classifying means comprising a second-stage fine powder classifier set to 0.9 μm, the weight average particle diameter was 7.2 μm, and the coefficient of variation B of the number distribution was 26.1% (particle diameter of 4.0 μm or less). 8.6 particles
It contains 10.1% by number of particles having a particle size of 8.0 μm or more. ) Was obtained, but the classification yield was 58%. When the image evaluation was performed on the obtained medium powder, there was almost no fog, and a good image quality was obtained.

(Comparative Example 3) Using the same toner pulverization raw material as in Example 4, pulverization and classification were performed according to the flowchart of FIG.

A crusher shown in FIG. 17 (pressure 6.0 kg / cm ² (G), 6.0 Nm ³ /
min compressed air) and the same apparatus as in Example 1 was used as a coarse powder classifier, and a dispersion separator DS5UR (manufactured by Nippon Pneumatic Industries, Ltd.) was used as a fine powder classifier.

The raw material is supplied at a rate of 12 kg / h,
Weight average particle diameter 7.2 μm, variation coefficient B of number distribution is 3
1.0% (20.2% by number of particles having a particle size of 4.0 μm or less
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.

(Comparative Example 4) Using the same toner pulverization raw material as in Example 4, pulverization and classification were performed according to the flowchart of FIG.

A crusher shown in FIG. 17 (pressure 6.0 kg / cm ² (G), 6.0 Nm ³ /
min compressed air) and the same apparatus as in Example 1 was used as a coarse powder classifier, and a dispersion separator DS5UR (manufactured by Nippon Pneumatic Industries, Ltd.) was used as a fine powder classifier.

The pulverization was carried out by reducing the supply amount of the pulverized raw material to 5 kg / h.
m could not be obtained.

Table 1 summarizes the results of the above Examples and Comparative Examples.

[0151]

[Table 1]

[0152]

According to the method for producing a toner of the present invention, a toner having a sharp particle size distribution can be obtained with a high pulverization efficiency and a high classification yield, and further, the occurrence of fusion, aggregation, and coarsening of the toner can be prevented. There is an advantage that stable and continuous production can be performed by preventing device-like abrasion due to toner components. Also, by using the toner manufacturing method of the present invention, compared with the conventional method, an electrostatic charge having a stable and high image density, excellent durability, and an excellent predetermined particle size without image defects such as fog and poor cleaning. An image developing toner can be obtained at low cost. Further, there is an advantage that a toner for developing an electrostatic charge image having a small particle diameter (particularly 3 to 8 μm) can be effectively obtained.

[Brief description of the drawings]

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

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

FIG. 3 is a schematic cross-sectional view of a pulverizing apparatus which is a specific example for implementing the impingement type air current pulverizing means of the present invention.

FIG. 4 shows a partially enlarged view of FIG. 4;

FIG. 5 is a sectional view taken along line AA ′ of FIG. 4;

FIG. 6 is a sectional view taken along line BB ′ of FIG. 4;

FIG. 7 is a sectional view taken along the line CC ′ of FIG. 4;

FIG. 8 is a sectional view taken along the line DD ′ of FIG. 4;

FIG. 9 is a schematic cross-sectional view of a pulverizing apparatus which is another specific example for implementing the impingement type air current pulverizing means of the present invention.

FIG. 10 is a sectional view taken along line GG ′ of FIG. 9;

FIG. 11 is a sectional view taken along the line HH ′ of FIG. 9;

FIG. 12 is a schematic sectional view of a preferred embodiment of a first classifying means used in the production method of the present invention.

FIG. 13 is a sectional view taken along the line KK 'of FIG.

FIG. 14 shows a front view of a conical collision member having a projection in the center.

FIG. 15 shows a plan view of a conical collision member having a projection in the center.

FIG. 16 is a flowchart for explaining a conventional manufacturing method.

FIG. 17 shows a schematic cross-sectional view of a conventional collision type airflow pulverizer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Acceleration pipe 2 Acceleration pipe throat part 3 High pressure gas ejection nozzle 4 Pulverized material supply port 5 Pulverized substance supply pipe 6 High pressure gas supply port 7 High pressure gas chamber 8 High pressure gas introduction pipe 9 Acceleration pipe outlet 10 Collision member 11 Collision member support Body 12 crushing chamber 13 crushed material discharge port 14 side wall 15 edge of collision member 16 collision surface 17 front wall 80 crushed material

Continued on the front page (72) Inventor Satoshi Mimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc. (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/08- 9/097 B02C 19/06 B07B 7/08

Claims (1)

(57) [Claims] 1. A mixture containing at least a binder resin and a colorant is melt-kneaded, the kneaded product is cooled, and the cooled product is pulverized by a pulverizing means to obtain a pulverized product. Means to classify into coarse powder and fine powder, and the classified coarse powder is finely pulverized by a collision type air current pulverizing means to produce fine powder,
The generated fine powder is circulated to a coarse powder classifying means, and the classified fine powder is introduced into a multi-stage fine powder classifying means having at least two or more stages of fine powder classifying means. In a method for producing a toner for developing an electrostatic image from a body, the collision-type airflow crushing means comprises: an accelerating tube for conveying and accelerating a coarse powder supplied by a high-pressure gas; A pulverizing chamber for finely pulverizing the powder; a coarse powder supply port for supplying coarse powder into the accelerating tube at a rear end of the accelerating tube; A crushing member having a colliding surface provided opposite to the opening surface; the crushing chamber has a side wall for further crushing the crushed material of the coarse powder crushed by the colliding member; the closest distance between the edge of the collision member 1 _1, the milling chamber front wall facing the impact surface Shorter than the closest distance 1 ₂ between the edge of the collision member, in the pulverizing chamber, after further grinding the ground product of the milling and coarse coarse powder in the collision surface and the side wall of the impact member, coarse The fine powder circulated to the classification means and classified by the coarse powder classification means is introduced into a multi-stage fine powder classification means having at least two or more stages of fine powder classification means, and the fine powder mainly composed of a group of particles having a predetermined particle size or less. And a multi-stage fine powder classifying step of classifying and collecting a medium powder mainly composed of a particle group having a predetermined particle size range, wherein the classifying point A of the multi-stage fine classifier is The following conditions (1) to (4): 1.0 (μ) <A _n-1 <5.0 (μ) (1) 1.5 (μ) <A _n <7.0 (μ) (2) _An-1 < _An (3) 2 ≦ n ≦ 5 (4) (wherein the classification point A is a particle size corresponding to a partial classification efficiency of 50%, 50% A value called a classification diameter D _p50 (μm) is shown, n is the number of stages of the fine powder classification means constituting the multi-stage fine powder classification means, and the classification point of the first stage of the multi-stage fine powder classification means is A
_1, the second stage of classification points A _2, n-th stage is defined as A _n. ), And the weight-average particle diameter (D ₄ ) is 3 to 8 μm, and the variation coefficient B of the number distribution is the following condition (5) 20 ≦ B ≦ 40 (5) (where, B is a coefficient of variation (S /
D ₁ ) × 100, where S indicates the standard deviation in the number distribution in the medium powder, and D ₁ indicates the number average particle size (μm) in the medium powder. A method for producing a toner for developing electrostatic images, characterized by satisfying the following.