JP3210774B2 - Manufacturing method of toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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 the high image quality and high definition of copiers and printers, the performance required for toner as a developer has become even more severe, and the particle size is smaller, there is no coarse particle, there is less sharp fine powder. Those having a particle size distribution have been required.

[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 disclosed 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. Used, and, if necessary, dry-mixing a releasing agent or a fluidity-imparting agent, and then melt-kneading with a general-purpose kneading device such as a roll mill and an extruder, and after cooling and solidifying, a jet stream type pulverizer. And, it is pulverized by various pulverizing devices such as a mechanical impact type pulverizer, and classified by various air classifiers to make the particle size necessary. The toner thus obtained is dry-mixed with a fluidizing agent, a lubricant and the like, if necessary, to obtain 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.

In order to obtain toner particles which are fine particles as described above, a method shown in a flowchart of FIG. 18 has conventionally been generally employed. The crushed toner material, which is a pulverized raw material, is continuously or sequentially supplied to a coarse powder classifying means and classified, and the coarse powder mainly composed of a group of coarse particles having a specified particle size or more is sent to the pulverizing means and pulverized. After that, it is circulated again to the coarse powder classification means. On the other hand, a finely pulverized toner mainly composed of particles within the other specified particle size range and particles not larger than the specified particle size is sent to fine powder classification 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 apparatuses are used. For pulverizing a coarsely pulverized toner mainly composed of a binder resin, a jet pneumatic pulverization using a jet air flow as shown in FIG. Crushers, in particular impingement airflow crushers, are used. A collision type air flow pulverizer using a high-pressure gas such as a jet stream transports a powder raw material by a jet stream, injects the powder raw material from an outlet of an acceleration tube, and provides the powder raw material facing an opening surface of an outlet of the acceleration tube. The raw material is crushed by the impact force of the colliding member. For example, in the collision type air pulverizer shown in FIG. 19, 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 raw material is sucked into the acceleration pipe 46 from the powder raw material supply port 40 communicated in the middle of the pipe 46, and the powder raw material is ejected together with the high-pressure gas to collide with the collision surface of the collision member 43. are doing.

[0006]

However, in the above-mentioned conventional collision type air-flow pulverizer shown in FIG. 19, the supply port 40 for the material to be pulverized is provided in the middle of the accelerating pipe 46. Immediately after passing through the to-be-pulverized material supply port 40, the to-be-pulverized material to be pulverized is dispersed in the high-pressure gas flow while changing the flow path toward the outlet direction of the accelerating tube by the high-pressure gas flow ejected from the high-pressure gas supply nozzle 47. It is suddenly accelerated. 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 influence of the inertia force, and the relatively fine particles flow through the high flow portion in the acceleration tube. Without being dispersed uniformly, the material to be ground is separated into a high flow and a low flow, and the material to be ground partially collides with the opposing collision member, and the pulverization efficiency is easily reduced. However, there is a problem that the processing capacity is easily lowered.

[0007] 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 material such as a resin. However, there is a problem that fusion, coarse graining, aggregation and the like of the material to be crushed easily occur. Furthermore, if the material to be ground has abrasion properties, local powder abrasion 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 is achieved. Then, there was a problem to be improved.

To solve the above problems, the tip of the collision surface of the collision member has a conical shape having an apex angle of 110 to 175 ° (JP-A-1-254266). (Japanese Utility Model Laid-Open No. 1-148740) has proposed a collision plate shape having a projection on a plane intersecting at right angles to the extension of the central axis of the collision plate. In these pulverizers, since the local increase in dust concentration near the collision surface can be suppressed, the fusing, coarsening, and agglomeration of the pulverized material can be somewhat reduced, and the pulverization efficiency is slightly improved. However, further improvements are desired.

For example, to obtain a particle group having a weight average diameter of 8 μm and a coefficient of variation B of the number distribution (defined below) of 33%, a classification mechanism for removing the coarse powder region. The raw material is pulverized to a predetermined average particle size by a pulverizing means such as an impinging air current pulverizer having a particle size and classified, and the pulverized material after the coarse powder is removed is subjected to another classifier to remove the fine powder. Medium powder is obtained. In addition, the weight average particle diameter described here is data measured using a Coulter Counter TA-II manufactured by Coulter Electronics Co., Ltd. (USA) using an aperture of 100 μm.

As described above, in the conventional manufacturing method, particularly when the weight average particle size of the toner is 8 μm or less, the smaller the weight average particle size, the lower the energy efficiency in the pulverizing means and the classification yield in the fine powder classification means. There is a problem that the rate is lowered. As a method for improving the yield reduction by the fine powder classification means in the conventional method, Jiro Nakayama, Kazuhiro Yonezawa;
As described in Powder and Industry, April, p. 45 (1984), or the latest ultra-fine pulverization process technology, p. 347 (1985), classification means are provided in multiple stages, and a small machine is installed on the downstream side. A method of using is proposed. Although this method can improve the yield to some extent, it is mainly intended to reduce the decrease in the classification accuracy and the classification yield due to the increase in the capacity of the classification means. It is true that an increase in the rate 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 ultrafine particles generated in the pulverizing step. In the case of a single-stage fine powder classifying means as shown in FIG. 18 which is a conventional method, the chance of removing the ultrafine particles is small once, and the ultrafine particles cannot be completely removed. Also, as described in Jiro Nakayama and Kazuhiro Yonezawa; Powder and Industry, April, p. 45 (1984) or the latest ultra-fine pulverizing process technology, p. 347 (1985), a fine powder classification means is used. In the case of multiple stages, the removal of extremely fine particles is considerably improved as compared with the case of one stage. However, the image quality is not yet enough,
There is a strong need for further improvement in image quality.

Further, regarding such a conventional method,
Since the fine particle classifying means for removing the fine powder has to be sent a particle group in which coarse particles having a certain particle size or more are completely removed, the load on the pulverizing means is increased, and the throughput is reduced. In order to completely remove a group of coarse particles having a specific particle size or more, it is apt to be excessively pulverized, and as a result, a phenomenon such as a decrease in yield in a fine powder classification means for removing fine powder in the next step is easily caused. There was a problem.

In the fine powder classification means for removing fine powder, aggregates composed of ultrafine particles may be generated, and it is difficult to remove the aggregates as fine powder. There is a problem that it is difficult to obtain a product having a fine particle size distribution as a result of mixing in the final product. Further, there is a problem that the aggregates are broken down in the toner to become extremely fine particles, which is one of the causes of deteriorating the image quality.

In order to address the above problems, Japanese Patent Application Laid-Open
No. 101858 (corresponding US Pat. No. 4,844,349)
Has proposed a toner manufacturing method and apparatus using a multi-divided classifying means as a coarse powder classifying means, a pulverizing means and a fine powder classifying means. However, there is a need for 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.

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 an electrostatic image developing toner. 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 addition, the present invention provides a particle product having a precise predetermined particle size distribution from a group of solid particles formed by pulverizing after melt-kneading a mixture containing a binder resin, a colorant and an additive, cooling the melt-kneaded material, (Used as a toner) efficiently and with a high yield. Furthermore,
In the present invention, the weight average particle diameter is 3 to 8 μm (preferably 3 to 8 μm).
An object of the present invention is to provide a method for efficiently producing a toner for developing an electrostatic image of 7 μm).

[0016]

The above object is achieved by the present invention described below. That is, in the present invention, a mixture containing at least a binder resin and a colorant is melt-kneaded, the kneaded material is cooled, and the cooled material is pulverized by a pulverizing means to obtain a pulverized product. The coarse powder is classified into coarse powder and fine powder by the coarse powder classifying means, and the classified coarse powder is finely pulverized by the impingement airflow pulverizing means to generate fine powder.The generated fine powder is circulated to the coarse powder classifying means, A method of introducing a classified fine powder into a multi-stage fine powder classifying means comprising at least two or more fine powder classifying means to produce a toner for developing an electrostatic charge image from a medium powder having a predetermined particle size range obtained by classification. In the above, the impingement-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; Has a coarse powder supply port for supplying coarse powder into the accelerating tube; A collision member having a collision surface provided opposite to the opening surface of the outlet; a grinding chamber having a side wall for further grinding the coarse powder pulverized by the collision member by collision; closest distance 1 ₁ between the edge of the side wall and the collision member is shorter than the closest distance 1 ₂ between the grinding chamber front wall facing the impact surface and the edge of the collision member, in the pulverizing chamber, the collision After crushing the coarse powder and further crushing of the crushed powder on the collision surface and the side wall of the member, the fine powder circulated to the coarse powder classifying means is classified into at least two stages by the coarse powder classifying means. A fine powder classifying means, and a final stage fine powder classifying means is a production method which is introduced into a multi-stage fine powder classifying means comprising a multi-divided classifying means obtained by fractionating at least three. The group is lowered in a curve by the Coanda effect, and a predetermined grain is The coarse powder mainly composed of the above-mentioned particle groups is divided and collected, and the medium powder mainly composed of the particle group having a predetermined particle size range is divided and collected in the second fractionation area. A fine powder mainly composed of a group of particles having a particle size equal to or smaller than a predetermined particle size is collected and circulated to the crushing means or the coarse powder classifying means. Therefore, the classification point A of the fine powder classifying means constituting the multi-stage fine powder classifying means has the following condition: 1.0 <A ₁ <‥‥ <A _n-1 <5.0 (1) 1.5 <A _n <7.0 (2) A ₁ <‥‥ <A _n-1 <A _n (3) 2 ≦ n ≦ 5 (4) [The classification point A in the formula is a particle size corresponding to a partial classification efficiency of 50%, and is 50%. What is called a classification diameter D _P50 (μm) is shown. n indicates the number of stages of the multistage fine powder classification means. The classification point of the first stage of a multistage fine powder classifying A _1, classification point of the second stage to define a classification point of A _2, n-th stage and A _n. Incidentally, classification point of the final stage of the multi-stage fine powder classifying means, the first fractionation zone and a second
Classification point of the fractionation area. And the weight average particle diameter D _{4 of} the middle powder collected in the multi-stage fine powder classification step is 3 to 8
μm and the variation coefficient B of the number distribution is as follows: 20 ≦ B ≦ 40 (5) [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. ], And a method for producing a toner for developing an electrostatic image.

[0017]

Preferred embodiments of the present invention will be described below 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 coarse powder classification means,
The coarse powder is classified into coarse powder and fine powder by a coarse powder classification means. The coarse powder is introduced into the pulverizing means, pulverized, and after the pulverization, is again introduced into the coarse powder classification means.

On the other hand, the fine powder having a predetermined amount or less
The fine-powder classification means of more than one stage and the final-stage fine-powder classification means are supplied to a multi-stage classification means comprising a multi-division classification means, and are classified into at least fine powder, medium powder and coarse powder. The classified coarse powder is introduced into a pulverizing means or a coarse powder classifying 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, 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% by controlling the classification and pulverization conditions. A toner having a small particle size of about 40% can be efficiently produced. FIG. 2 shows an example of the device system of the present invention.

In the apparatus system of the present invention, 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. The primary fine powder classified here is sent to the second fixed-quantity feeder 110 via the collection cyclone 107, and is supplied to the first-stage fine powder classifier 22 via the primary fine powder supply injection feeder 202.
Introduced in 0. On the other hand, 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.

The first gas introduced into the first stage fine powder classifier 220
The secondary fine powder is classified into primary fine powder and secondary fine powder, and the primary fine powder is collected by the collecting cyclone 203. The secondary fine powder is 2
After being fed into the third fixed-quantity feeder 210 via the next fine powder supply injection 221 and further via the collection cyclone 201, and then via the vibrating feeder 103 and the fine powder supply nozzle 116, the second-stage fine powder classification is performed. Machine (multi-segmentation classifier) 101.

Second stage fine classifier (multi-divider classifier) 101
The secondary fine powder introduced into the crusher is classified into a secondary fine powder, a medium powder and a coarse powder, and the coarse powder is collected by a collecting cyclone 106, and then crushed by a pulverizer 108 (or a coarse powder classifier). 109). The secondary fine powder and the medium powder are collected by the collecting cyclones 104 and 105, respectively. As the crushing means used in the present invention, for example, a collision type air flow crusher of the type shown in FIGS.

In FIG. 4, the material 80 supplied from the material supply pipe 5 is supplied to the accelerating tube throat 2 of the accelerating tube 1.
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 passes through a plurality of high-pressure gas introduction pipes 8, and sharply moves from the high-pressure gas ejection nozzle 3 toward the acceleration pipe outlet 9. Spouting while expanding.

At this time, the crushed object 80 is accelerated from the crushed object supply port 4 by the ejector effect generated near the acceleration tube throat portion 2 while being accompanied by the gas coexisting with the crushed object 80. The collision surface 1 of the collision member 10 that is rapidly accelerated toward the direction of the tube outlet 9 while being uniformly mixed with the high-pressure gas in the acceleration tube throat portion 2 and faces the acceleration tube outlet 9.
6 collides in a state of a uniform solid-gas mixed flow without deviation of the 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.
As shown in FIG. 7, it is a shape having a conical projection,
This is preferable in that the pulverized material is uniformly dispersed in the pulverization chamber 12 and the secondary collision with the side wall 14 is efficiently performed. Furthermore,
When the pulverized material discharge port 13 is located behind the collision member 10, the pulverized material can be smoothly discharged.

FIG. 5 shows an enlarged view of the grinding chamber. 5, 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.
Also, recently because contact distance 1 ₁ is shorter than the closest distance 1 _2, it is possible to efficiently perform the secondary collision of the pulverized material in the sidewall. Furthermore, in order to uniformly disperse the pulverized material and efficiently perform the secondary collision on the side wall 14, the collision member 10 has a tilt θ ₁ smaller than 90 ° with respect to the long axis of the acceleration tube (more preferably, 5
It is preferable that an inclined surface having an inclination of 5 ° to 87.5 °, more preferably 60 ° to 85 °) is the collision surface.

As shown in FIG. 19, the collision surface 41 is
Compared with the conventional crusher, which is a 90 ° flat collision member, the crusher of the present invention having an inclined collision surface, when crushing a resin or a sticky substance, Does not easily occur, and the 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.

The inclination of the accelerator tube 1 in the major axis direction is preferably within a range of 0 to 45 ° with respect to the vertical direction.
Processing can be performed without the material to be ground 80 being blocked at the material supply port 4 for the material to be ground. If the material to be crushed has poor fluidity, if the crushed material has a cone-shaped member below the supply pipe 5, the crushed material tends to stay in the lower part of the cone-shaped member although the amount is small. The inclination of the pipe 1 is preferably 0 to 20 ° with respect to the vertical direction (more preferably 0 to 20 °).
Within the range of 5 °), the material to be ground can be smoothly supplied to the accelerating tube without stagnation of the material to be ground in the lower cone portion.

FIG. 6 is a sectional view taken along the line AA 'in FIG. It is understood from FIG. 6 that the material to be ground 80 is smoothly supplied to the acceleration tube 1. Intersects the extension at right angles with the acceleration tube central axis, the closest distance 1 ₂ between the absolute end 15 of the impact surface 16 of the collision member 10 to the surface facing the accelerating tube outlet 9, the diameter of the impact member 10 0.2 The range of 2 times to 2.5 times is preferable for efficiency of pulverization, and the range of 0.4 times to 1.0 times is more preferable. The closest distance 1 ₂ is less than 0.2 times, there are cases where dust concentration in the vicinity of the impact surface 16 becomes too addition,
If it exceeds 2.5 times, the impact force is weakened, and as a result, the pulverized material tends to decrease.

The closest distance 1 ₁ between the absolute end 15 and the side wall 14 of the collision member 10 is 0.1 times the diameter of the impact member 10-2
A double range is preferred. 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.
If it exceeds twice, the effect of the secondary collision of the object to be ground on the inner wall 14 of the grinding chamber decreases, and the grinding efficiency tends to decrease.

More specifically, the length of the acceleration tube 1 is 50
Preferably, the diameter of the collision member 10 is 30 to 3 mm.
It preferably has a thickness 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. 7 is a sectional view taken along the line BB 'in FIG. In FIG. 7, the distribution state of the crushed object in a vertical plane with respect to the vertical direction of the crushed object supply port 4 passing through the crushed object supply port 4 is more biased as the inclination of the acceleration tube 1 with respect to the vertical direction is larger. The smaller the inclination, the more uniform. Therefore, it was confirmed that the best inclination of the acceleration tube 1 was within the range of 0 to 5 ° by changing the acceleration tube 1 to a transparent acrylic resin internal observation acceleration tube.

FIG. 8 is a sectional view taken along the line CC 'in FIG. In FIG. 8, the object to be crushed is discharged backward through the crushing chamber 12 between the collision member support 11 and the side wall 14. FIG. 9 is a sectional view taken along the line DD ′ in FIG. FIG.
In the above, two high-pressure gas introduction pipes 8 are arranged, but in some cases, even if the number of the high-pressure gas introduction pipes 8 is one, three
It may be more than books.

FIGS. 10 to 12 are schematic views showing another embodiment of the impinging airflow pulverizer of the present invention. 10, the same numbers as those in FIG. 4 indicate the same members. In the collision type air-flow crusher shown in FIG. 10, the inclination of the acceleration tube 1 in the major axis direction with respect to the vertical line is preferably 0 to 45 ° (more preferably 0 to 20 °, and still more preferably 0 to 5 °). ), And the material to be crushed 80 is
The gas is further supplied to the acceleration tube 1 through the acceleration 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. It has high speed. The crushed material 80 ejected from the acceleration pipe outlet 9 into the crushing chamber 12 at a high speed in this manner is
The powder is crushed by colliding with the collision surface 16 of the collision member 10.

In the collision type air current pulverizer shown in this figure, an object to be pulverized 80 is charged from the center of the throat 4 of the acceleration tube 1 and
The crushed object 80 in the accelerating tube 1 is dispersed, and the crushed object 80 is uniformly ejected from the accelerating tube outlet 9.
By efficiently colliding with the colliding surface 16, the crushing efficiency can be improved as compared with the related art.

The collision surface 16 of the collision member 10 is
In the case of a conical shape as shown in FIG. 16 or a shape having a conical projection on the collision surface as shown in FIGS. 16 and 17, the dispersion of the material to be crushed after the collision becomes good, and No fusing, agglomeration, and coarsening occur, and it is possible to pulverize at a high dust concentration.In the case of abraded materials, the abrasion that occurs on the inner wall of the accelerating tube and the collision surface of the collision member The service life can be extended without local concentration, and stable operation can be achieved.

FIG. 11 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. 12 is a sectional view taken along the line HH 'in FIG. As in the pulverizer shown in FIG. 4, if the inclination of the acceleration tube 1 in the long axis direction is within the range of 0 to 45 °, the material to be pulverized 80
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 portion of the supply pipe 5 for the material to be crushed. Therefore, when a material to be ground having poor fluidity is used, the inclination of the acceleration tube 1 is preferably 0 to 20 ° (more preferably 0 to 5 °).
Within the range, there is no stagnation of the crushed object 80, and the crushed object 80 is smoothly supplied into the acceleration tube 1.

When the crusher shown in FIG. 4 is compared with the crusher shown in FIG. 10, the crusher shown in FIG.
0 was satisfactorily dispersed and supplied into the acceleration tube, so that the pulverization efficiency was good.

As the coarse powder classification means used in the present invention,
An airflow classifier is used. For example, a DS classifier manufactured by Nippon Pneumatic Industries and a micron separator manufactured by Hosokawa Micron Corporation may be used. Preferably, by using the airflow classifier shown in FIGS. 13 and 14, the classification accuracy of fine powder and coarse powder can be improved.

In FIG. 13, reference numeral 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, and the upper part of the classifying chamber 28 has an annular guide chamber 26 attached to the upper part of the main body casing 36 and a conical shape (umbrella shape) in which the center is higher.
Is closed by an upper 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 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 via the supply tube 24 be uniformly distributed to the respective introduction louvers 27 in order to accurately classify them. Introduction louver 2
It is necessary that the flow path to reach 7 has a shape that does not easily cause concentration due to centrifugal force. 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 via the introduction louver 27, and a remarkable improvement in dispersion is obtained in the supply in comparison with the conventional method. or,
The introduction louver 27 is movable, and the introduction louver interval can be adjusted. Classification louvers 37 arranged in the circumferential direction are provided below the main body casing 36, and classification air causing a swirling flow from outside to the classification chamber 28 is taken in through the classification louvers 37.

At the bottom of the classifying chamber 28, a conical (umbrella-shaped) classifying plate 29 having a raised central portion 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 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. Classification room 28 from between the classification louvers 37
The swirling flow required for classification is caused by the suction air flowing into the tank.

The air flow classifier preferably used as the coarse powder classifying means has the above-described 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 the air containing the powdered material and the newly supplied powdered material composed of the pulverized raw material is supplied, the air containing the powdered material passes between the guide chambers 26 and between the louvers 27 and turns into the classification chamber 28. While flowing, it is dispersed at a uniform concentration.

The powder material swirled into the classification chamber 28 is swirled by the suction fan 34 connected to the fine powder discharge pipe 30 along the suction air flow flowing from between the classification louvers 27 below the classification chamber. The coarse powder which is centrifuged into coarse powder and fine powder by the centrifugal force exerted by each particle, and which circulates around the outer circumference in the classification chamber 28 is discharged from the lower hopper 32 through the coarse powder discharge port 38, The material to be ground is supplied to the supply pipe 5. The fine powder which moves to the center along the upper inclined surface of the classification plate 29 is supplied to the fine powder collecting means 33 by the fine powder discharge pipe 30.
After being discharged into the multistage 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 finely distributed powder.

FIG. 14 is a sectional view taken along the line KK 'in FIG. By using the airflow classifier shown in FIG. 13 in combination with the above-mentioned collision airflow pulverizer, mixing of the fine powder into the pulverizer is suppressed or prevented well, and excessive pulverization of the pulverized material is prevented. In addition, the classified coarse powder is smoothly supplied to the pulverizer, further uniformly dispersed in the accelerating tube, and pulverized well in the pulverizing chamber, so that the yield of the pulverized material and the energy efficiency per unit weight can be improved. I can do it.

In 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 as the fine powder classifying means except for the fine powder classifying means in the final stage. For example, Nippon Pneumatic Industrial D
Examples include an S type classifier, a micron separator and an ATP type classifier manufactured by Hosokawa Micron, and a turbo classifier manufactured by Nisshin Engineering.

In the fine powder classifying means constituting the multi-stage fine powder classifying means used in the present invention, as means for providing the multi-divided classification area which is the final stage fine powder classifying means, for example, as shown in FIG. A multi-segment classifier of the system shown will be exemplified as one of the specific examples. In FIG. 15, the side wall is 12
2 and 124, the lower wall has the shape shown by 123 and 125, and the lower walls 123 and 12
5 is a knife-edge type classification edge 117 and 11 respectively.
8, the classification zone is divided into three.

A fine powder supply nozzle 116 that opens into 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 to the bottom of the nozzle and that draws a long elliptical arc is provided. Classification room upper wall 127
Is a knife-edge type inlet edge 11 toward the lower part of the classification chamber.
9 and further, in the upper part of the classification chamber, there are provided air inlet pipes 114 and 115 which open to the classification chamber.

The air inlet pipes 114 and 115 are provided with first gas introduction adjusting means 120 such as a damper, second gas introduction adjusting means 121, and static pressure gauges 128 and 129. The positions of the classification edges 117 and 118 and the inlet edge 119 are as follows.
It depends on the type of fine powder and on the desired particle size. Discharge ports 111, 112, and 113 that open into the room are provided on the bottom surface of the classifying chamber corresponding to the respective dividing areas. The outlets 111, 112 and 113 may be provided with opening / closing means such as valve means, respectively.

The fine powder supply nozzle 116 is composed of a right-angled cylinder and a pyramid-shaped cylinder. When the ratio of the inner diameter of the right-angled cylinder to the innermost diameter of the narrowest part of the pyramid-shaped cylinder is set to 20: 1 to 1: 1, Good introduction speed is obtained. The classification operation in the multi-division classification region configured as described above is performed, for example, as follows. The pressure in the classification area is reduced through at least one of the discharge ports 111, 112 and 113, and the air flow flowing by the reduced pressure in the fine powder supply nozzle 116 opened in the classification area causes a velocity of 50 m / sec to 300 m / sec. Then, the fine powder is supplied to the classification area via the fine powder supply nozzle 116.

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 break up the agglomeration of the fine powder, and the classification yield and the classification accuracy tend to be lowered. Further, 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 gas such as air flowing in at that time, and the size of each particle and the size of the weight are increased. Classified according to. If the specific gravity of the particles is the same, large particles (coarse powder)
Is outside the airflow (ie, the third
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
Are classified into the first segmentation area on the right side of. The coarse powder thus classified is discharged from a discharge port 111, the medium powder is discharged from a discharge port 112, and the fine powder is discharged from a discharge port 113, respectively.

For the introduction of the fine powder into the classification area, a method of sucking and introducing using the suction force of the cyclone, and providing a fine powder supply nozzle with an 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. The suction introduction method or the introduction method using an air conveying means such as injection is preferable because the sealing property of the apparatus system is not required as compared with the pressurized introduction method.

Injection 14 into fine powder supply nozzle
FIG. 3 shows an example of the device when the device 7 is attached. 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. Multi-divider classifier 101
The size of the classification area is usually [10 cm to 50 cm] x
Since it is [10 cm to 50 cm], the fine powder can be classified into three or more particle groups in 0.1 to 0.01 seconds or less.

When the multi-segment classifier 101 is fractionated into three, the fines are divided into coarse powder (particles having a specified particle size or more) and medium powder (particles having a specified particle size) by the multi-segment classifier 101. And fine powder (particles having a specified particle size or less). Thereafter, the coarse powder is returned to the crusher 108 through the discharge port 111 and 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 coarse powder classifier 109 and reliably perform the 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 through the discharge port 112, collected by the collection cyclone 105, and collected as a toner product 151. The fine powder is supplied to the outlet 113
And collected by the collection cyclone 104, and then collected as fine powder 141 having an irregular particle diameter. The collection cyclones 104, 105, and 106 also function as suction pressure reducing means for sucking and introducing fine powder into the classification area via the fine powder supply nozzle 116.

The number of stages of the fine powder classifying means constituting the multi-stage fine powder classifying 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 last stage is preferably a multi-division classification means.

In the case where 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, the chance of removing ultra-fine particles (the number of times) is small, so that the image quality is reduced, especially the fog property is reduced. Led to a decline. In particular, in a region where the weight average particle size of the toner is 8 μm or less, this tendency becomes more 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 except for the fine powder classifying means at the last stage may be either the same model or a combination of different models.

Further, the classification conditions of the fine powder classifying means constituting the multi-stage fine powder classifying means constituting the fine powder classifying means are determined by setting classification conditions so as to satisfy the following equations (1) to (4). The removal efficiency of the fine particles is extremely high, and the classification yield can be improved satisfactorily. Here, the classification point is a particle diameter corresponding to a partial classification efficiency of 50% and is called a 50% classification diameter D _P50 (μm).

That is, in order to efficiently remove the ultrafine particles, improve the image quality (especially, fogging property), and further improve the classification yield, the fine powder classification means constituting the multi-stage fine powder classification means Classification point A of the following condition (1)
It is good to set to formula (4). When the formula (3) under the following condition satisfies An _-1 > An, the efficiency of removing ultrafine particles is good, but the classification yield is undesirably low.

1.0 <A ₁ <‥‥ <A _n−1 <5.0 (1) 1.5 <A _n <7.0 (2) A ₁ <‥‥ <A _{n −1} <A _n (3) 2 ≦ n ≦ 5 (4)

[Classification point A in the formula means 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). 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 as used herein refers to the volume cumulative particle size distribution measured with a Coulter Counter TA-II manufactured by Coulter Electronics (USA) using an aperture of 100 μm. Further, n 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 class classification point is _An is defined. The classification points at the final stage of the multi-stage fine powder classification means are the classification points of the first fractionation area and the second fractionation area. ]

For the classification point, an optimum condition may be adopted 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 flowchart of FIG. 1 is not limited to this. For example, one pulverizing means and two coarse powder classifying means or
The number of pulverizing means and coarse powder classifying means may be two or more. What kind of combination constitutes the pulverizing step may be appropriately set depending on 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 final 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 diameter and the true specific gravity of the powder.

The raw material to be introduced into the coarse powder classification means is 2 mm
Or less, preferably 1 mm or less. Further, the raw material to be pulverized may be introduced into the medium pulverizing step and pulverized to about 10 μm to 100 μm as the raw material in the present invention.

In the conventional pulverization-classification method, in particular, as the weight average particle diameter of the toner is 8 μm or less and the weight average particle diameter becomes smaller, the energy efficiency in the pulverizing means decreases and the classification yield in the fine powder classification means decreases. Further, as the weight average particle size of the toner becomes smaller, the degree of aggregation of the toner particles increases, and moreover, the generation of extra fine particles increases, so that the extra fine particles generated by the pulverizing means cannot be completely removed by the fine powder classification means. In this case, the image quality (especially, the fog property) is lowered.

In the above-mentioned conventional method, in order to improve the yield of the fine powder classification means, an attempt has been made to use a multi-stage fine powder classification means. However, the classification accuracy and the classification yield mainly associated with an increase in the capacity of the classification means have been attempted. The method is intended to reduce the decrease in the particle size, and this method can improve the classification yield to some extent, and the fine powder classification means is also one of the methods for removing ultrafine particles.
Although improved compared to the column, it was still not sufficient, and the image quality (especially fog) was not satisfactory.

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

The method of the present invention uses a highly efficient grinding means
It is possible to pulverize the toner raw material, which has extremely high energy efficiency, and to reduce the production cost in the pulverization process. or,
By providing fine powder classification means in multiple stages, forming 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, and Extremely high removal efficiency of ultrafine particles can be achieved.

Further, 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, restrictions in the pulverization step are reduced, the capacity of the pulverizer can be maximized, the pulverization efficiency is improved, and the tendency to cause over-pulverization is reduced. Therefore, the fine powder can be removed 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 at the time of classification is long, agglomerates of fine particles which cause fogging of a developed image are easily generated. When aggregates of fine particles are generated, it is generally difficult to remove the aggregates from the intermediate 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 Agglomerates are disintegrated and removed as fine powder by the impact of movement, and even if there is any agglomerate that has escaped disintegration, it can be simultaneously removed to the coarse powder area, so it is possible to remove aggregates efficiently Becomes

The synergistic effect of using the high-efficiency pulverizing means, the multistage fine-powder classifying means having a controlled classification point, and the multistage classifying means at the final stage of the fine-powder classifying means constituting the multi-stage fine-powder classifying means, reduces the production cost, It is possible to produce a toner in which the amount of fine particles is extremely small and the image quality (especially, fogging property) is further improved.

The production method and production apparatus 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,
After sufficiently mixing a colorant or magnetic powder and a vinyl-based, non-vinyl-based thermoplastic resin, a charge control agent and other additives as necessary with a mixer such as a Henschel mixer or a ball mill, Melting, kneading and kneading using a hot kneader such as a kneader and an extruder, dispersing or melting the pigment or dye while the resins are mutually compatible, cooling and solidifying, followed by grinding and classification. And a toner can be obtained. The production method of the present invention is used in the pulverizing step and the classifying step.

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.

Specifically, for example, homopolymers of styrene and its substituted substances such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer ,
Styrene-vinyl naphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether Styrene-based copolymers such as copolymers, styrene-vinyl ethyl ether copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers Coalescence: 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, cumarone indene resin, petroleum Resin or the like can be used.

On the other hand, in a heat and pressure fixing method or a heat and pressure roller fixing method in which little or no oil is applied, a so-called offset in which a part of a toner image on a toner image support member is transferred to a roller. The phenomenon and the adhesion of the toner to the toner image supporting member are important issues. Further, a toner which is fixed with less heat energy has a property of easily blocking or caking during storage or in a developing device. Therefore, these problems must be considered at the same time.

The physical properties of the binder resin in the toner are most significantly involved in the above-mentioned phenomenon. According to the study of the present inventors, when the content of the magnetic substance in the toner is reduced, the toner is not fixed at the time of fixing. Although the adhesion of the toner to the toner image support is improved,
Not only does the offset phenomenon easily occur, but also blocking or caking tends to occur. Therefore, when using a heating and pressing roller fixing method in which almost no oil is applied in the present invention, selection of the binder resin becomes more important. Preferred binders include cross-linked styrenic copolymers or cross-linked polyesters.

Specific examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, and acrylic acid-2. Monocarboxylic acid having a double bond such as ethylhexyl, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; Acid, butyl maleate, methyl maleate, dicarboxylic acid having a double bond such as dimethyl maleate and the like; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene, propylene, Spot Vinyl monomers such as vinyl methyl ketone and vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Alternatively, two or more are used.

As the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used. Specific examples thereof include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; Carboxylic acid esters having two double bonds such as glycol diacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and Compounds having two or more vinyl groups are used alone or as a mixture of two or more.

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. Specifically, for example, polyethylene, polypropylene, polymethylene, polyurethane Elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-
Butadiene copolymer, styrene-isoprene copolymer,
There are linear saturated polyester, paraffin and the like.

It is preferable that a charge control agent is blended (internally added) to the toner particles before use. Depending on the charge control agent,
It is possible to control the amount of charge optimally according to the developing system. In particular, in the present invention, it is possible to further stabilize the balance between the particle size distribution and the charge, and to improve the image quality by each of the above-described toner particle size ranges. It is possible to clarify the function separation and mutual complementarity for the purpose.

Specific examples of the positive charge control agent include denatured products such as nigrosine and fatty acid metal salts; tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate and the like. Quaternary ammonium salts can be used alone or in combination of two or more. Among these, charge control agents such as nigrosine compounds and quaternary ammonium salts are particularly preferably used.

The following general formula

Embedded image R ₁ : H, CH ₃ R ₂ , R ₃ : Homopolymer 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, and these charge control agents also have the function of (all or part of) the binder resin at the same time. .

As the negative charge control agent, organometallic complexes,
A chelate compound is effective, and specific examples include aluminum acetylacetonate, iron (II) acetylacetonate, chromium or zinc 3,5-ditert-butylsalicylate, and the like, preferably acetylacetone metal complex, salicylic acid metal It is preferably a complex or a salicylic acid-based metal salt, more preferably a salicylic acid-based metal complex or a salicylic acid-based metal salt.

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

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

These ferromagnetic materials have an average particle diameter of 0.1 to
It is preferably 1 μm, more preferably 0.1 to 0.1 μm.
It is about 5 μm. The amount contained in the magnetic toner is preferably 60 to 100 parts by weight of the resin component.
It is 110 parts by weight, more preferably 65 to 100 parts by weight.

As the colorant used in the toner, conventionally known dyes and / or pigments can be used. Specifically, for example, carbon black, phthalocyanine blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine yellow and the like can be used. The content is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 20 parts by weight, based on 100 parts of the binder resin, and the transparency of the OHP film on which the toner image is fixed is further improved. For this purpose, the content is preferably 12 parts by weight or less, more preferably 0.5 to 9 parts by weight.

[0096]

Hereinafter, the present invention will be described in more detail with reference to 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 Co., Ltd.), a twin-screw kneader (PCM-75) set at 150 ° C.
(Type 30; Ikegai Iron Works Co., Ltd.). The obtained kneaded material was cooled, coarsely pulverized to 1 mm or less with a hammer mill,
A crushed product for toner production was obtained.

The obtained toner pulverized raw material was pulverized and classified by an apparatus system shown in FIG. Collision type air flow crusher 1
Numeral 08 uses the apparatus having the configuration shown in FIG. 4 and inclines the longitudinal direction of the acceleration tube with respect to the vertical line (hereinafter referred to as the acceleration tube inclination).
Is about 0 ° (that is, installed substantially vertically), and the impact member has a conical shape with a vertical angle of 160 ° and an outer mold (diameter).
Using those 100 mm, the closest distance 1 ₂ between the outermost edge of the impact surface of the accelerating tube outlet surface opposite to the collision member intersecting the acceleration tube central axis perpendicular is 50 mm, the shape of the grinding chamber A cylindrical grinding chamber having an inner diameter of 150 mm was used. Therefore, the closest distance ₁₁ is 25 mm.

As the coarse powder classifier 109, a classifier having the structure shown in FIG. 13 was used. A TIPLEX ultrafine classifier 200ATP (manufactured by Hosokawa Micron Corporation) is used as the first stage fine classifier, and an Elbow Jet EJ-15-3 type machine (Nippon Steel Mining Co., Ltd.) is used as the second stage fine classifier. Manufactured). Table type first metering machine 10
In step 2, the pulverized raw material is supplied at a rate of 28 kg / hr to an airflow classifier through a supply pipe 24 by an injection feeder, and the classified coarse powder is subjected to the collision through a coarse powder discharge hopper 32. It is supplied from the supply pipe 5 for the pulverized material of the airflow pulverizer.

Here, the pressure is 6.0 kg / cm ² (G),
After being pulverized using 6.0 Nm ³ / min compressed air, the mixture is circulated again to the airflow classifier while being mixed with the toner pulverization raw material supplied at the raw material introduction section, and is subjected to closed circuit pulverization to perform classification. The primary fine powder thus collected 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.

The weight average diameter of the primary fine powder at this time was 7.
It had a sharp particle size distribution of 2 μm and substantially no coarse powder of 16.0 μm or more. The particle size distribution of the toner can be measured by various methods.
This was performed using a Coulter counter.

The measuring apparatus includes a Coulter counter TA-
Type II (manufactured by Coulter), and an interface (manufactured by Nikkaki) that outputs the number distribution and volume distribution, and CX
-1 Connected to a personal computer (Canon). A 1% aqueous NaCl solution adjusted with primary sodium chloride was used as the electrolyte during the measurement.

The measuring method is as follows.
In 50 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 electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser,
The particle size distribution of 2 to 40 μm particles was measured by the above-mentioned Coulter Counter TA-II using an aperture of 100 μm as an aperture, and the weight average particle diameter and the number average diameter were determined.

The obtained primary fine powder is supplied to the second quantitative feeder 11.
0 and primary fine powder supply injection feeder 202
, A classification point of 2.9 at a rate of 33.6 kg / hr.
It was introduced into a first-stage fine powder classifier 220 constituting a multi-stage fine powder classification means set to μm. 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.

The classified primary fine powder is collected by the cyclone 2
03, and the secondary fine powder is sent to the third quantitative feeder 210 via the secondary fine powder supply injection feeder 221 and the collection cyclone 201, and further the vibration feeder 1
In order to disperse into three types of coarse powder, medium powder and secondary fine powder utilizing the Coanda effect through the fine powder supply nozzle 116 and the fine powder supply nozzle 116, a second-stage fine powder classifier constituting a multi-stage fine powder classification means is used. It was introduced into a multi-segmentation classifier 101. In the multi-segment classification device 101, the classification points of the first and second classification areas shown in FIG. 15 were set to 4.1 μm.

At the time of introduction, the suction force derived from the reduced pressure in the system due to the reduced suction pressure of the collecting cyclones 104, 105 and 106 communicating with the discharge ports 111, 112 and 113 of the multi-divided classifier 101, and the fine powder supply Nozzle 1
Compressed air from the injection attached to 16 was utilized. The introduced secondary fine powder was classified instantaneously in 0.01 seconds or less.

On the other hand, the classified coarse powder was collected by the collecting cyclone 106 and then introduced into the pulverizer 108 again.
The classified medium powder and secondary fine powder were collected by the collecting cyclones 105 and 104. The medium powder classified according to the present invention as described above has a weight average particle diameter of 7.1 μm and a coefficient of variation B of the number distribution of 26.2% (containing 8.6% by number of particles having a particle diameter of 4.0 μm or less). And contained 10.1% by number of particles having a particle size of 8.0 μm or more.) It had a sharp particle size distribution. Further, in this example, the ratio of the finally obtained medium powder to the total amount of the pulverized raw materials charged (that is, the classification yield) was 78%. In addition, when image evaluation was performed on the obtained intermediate powder, good results were obtained with almost no fog and good image quality.

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,
As the coarse powder classifier and the second-stage fine powder classifier, the same apparatus as in Example 1 was used, and as the first-stage fine powder classifier, Turbo Classifier TC-40 (manufactured by Nisshin Engineering) was used.

In this example, the pulverized raw material was 28.0 kg /
hr, to obtain a primary fine powder having a weight average particle size of 7.3 μm, and the primary fine powder has a classification point of 2.9 μm at a rate of 33.6 kg / hr. Fine powder classifier and classification point (classification point between first fractionation area and second fractionation area) is 4.1
Introduced into a multi-stage fine powder classifier comprising a second-stage fine powder classifier (multi-divide classifier) set to μm, the weight average particle diameter is 7.0 μm, and the coefficient of variation B of the number distribution is 26.1% (particle diameter It contains 8.5% by number of particles having a particle size of 4.0 μm or less, and has a particle size of 8.
It contains 9.8% by number of particles of 0 μm or more. ) Was obtained with a classification yield of 79.0%. In addition, when image evaluation was performed using the medium powder obtained in this example, there was almost no fog, and good image quality was obtained.

Example 3 Using the same toner pulverizing raw material as in Example 1, pulverization and classification were carried out in the same apparatus system. The first-stage fine powder classifier and the second-stage fine powder classifier used in the collision-type airflow pulverizer and the coarse powder classifier were the same as those in Example 1. In this embodiment,
The pulverized raw material was supplied at a rate of 22.0 kg / hr to obtain a primary fine powder having a weight average particle size of 6.3 μm.
A first-stage fine powder classifier having a classification point of 2.4 μm at a rate of 6.4 kg / hr and a classification point (the first fractionation area and the second
(Second classification point with the fractionation area) is set to 3.5 μm.
Introduced into a multi-stage fine powder classifier comprising a multi-stage classifier (multi-segment classifier), the weight average particle diameter was 6.1 μm, and the coefficient of variation B of the number distribution was 22.8% (particles having a particle diameter of 4.0 μm or less were 9 .
9% by number, and 1.0% by number of particles having a particle size of 8.0 μm or more. ) Was obtained with a classification yield of 64%. In addition, when image evaluation was performed on the obtained medium powder, there was almost no fog, and good image quality was obtained.

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) 4.0 parts by weight The material was mixed with a Henschel mixer (FM-75).
After mixing well with a mold and a Mitsui Miike Kakoki Co., Ltd.), the mixture was kneaded and dispersed with a twin-screw kneader (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) set at a temperature of 100 ° C. The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill 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. 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.

In this example, the pulverized raw material was 25.0 kg /
hr, to obtain a primary fine powder having a weight average particle size of 7.3 μm, and the primary fine powder has a classification point of 2.9 μm at a rate of 30.0 kg / hr. Fine powder classifier and classification point (classification point between first fractionation area and second fractionation area) is 4.2
Introduced into a multi-stage fine powder classification means comprising a second-stage fine powder classifier (multi-divider classifier) set to μm, the weight average particle diameter is 7.1 μm, and the coefficient of variation B of the number distribution is 25.8% (particle diameter It contains 7.9% by number of particles having a particle size of 4.0 μm or less, and has a particle size of 8.
Contains 10.2% by number of particles of 0 μm or more. ) Was obtained with a classification yield of 73%. In addition, when image evaluation was performed on the obtained medium powder, there was almost no fog, and good image quality was obtained.

Example 5 Using the same raw material for toner pulverization as in Example 4, pulverization and classification were carried out in the same apparatus system. The same apparatus as that in Example 1 was used for the collision type air flow pulverizer, coarse powder classifier, first-stage fine powder classifier, and second-stage fine powder classifier.

In this example, the pulverized raw material was 17.0 kg /
hr, to obtain a primary fine powder having a weight average particle size of 6.2 μm, and the primary fine powder has a classification point of 2.6 μm at a rate of 20.4 kg / hr. Fine powder classifier and classification point (classification point between first fractionation area and second fractionation area) is 3.6
Introduced into a multi-stage fine powder classifying means comprising a second-stage fine powder classifier (multi-divide classifier) set to μm, the weight average particle diameter is 6.0 μm, and the coefficient of variation B of the number distribution is 23.0% (particle size It contains 9.8% by number of particles having a particle diameter of 4.0 μm or less, and has a particle diameter of 8.
It contains 1.2% by number of particles of 0 μm or more. ) Was obtained with a classification yield of 59%.
In addition, when image evaluation was performed on the obtained medium powder, there was almost no fog, and good image quality was obtained.

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. As a collision-type airflow pulverizer, a pulverizer (pressure 6.0) 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 is used, and the fine particle classifier is a dispersion separator DS5UR (Nippon Pneumatic). Industrial Co.) was used.

The pulverized raw material was supplied at a rate of 13.0 kg / hr, the weight average particle size was 6.8 μm, and the coefficient of variation B of the number distribution was B
Is 30.8% (19.5% by number of particles having a particle size of 4.0 μm or less and 12.5% by number of particles having a particle size of 8.0 μm or more). An intermediate powder having a distribution was obtained with a classification yield of 55%. When image evaluation was performed on the obtained medium powder, fog was considerably large, and good image quality was not obtained.

Comparative Example 2 Using the same toner pulverization raw material as in Example 1, pulverization and classification were carried out in the same apparatus system. The same apparatus as in Example 1 was used for the collision type air flow pulverizer, coarse powder classifier, first-stage fine powder classifier, and second-stage fine powder classifier.

Here, the pulverized raw material was 28.0 kg / hr.
And a primary fine powder having a weight average particle size of 6.7 μm is obtained. The primary fine powder has a classification point of 4.5 μm at a rate of 33.6 kg / hr. Classifier and classification point (classification point between first and second fractionation areas) is 2.9 μm
, A second-stage fine-particle classifier (multi-segment classifier) set to a weight average particle size of 7.2 μm and a number distribution coefficient of variation B of 26.3% (particle size of 4.0 μm or less). Particles containing 8.5% by number of particles and having a particle size of 8.0 μm or more.
Contains 0.2% by number. ) Was obtained, but the classification yield was 63%.
Incidentally, when image evaluation was performed on the obtained medium powder,
Good image quality was obtained with almost no fog.

Comparative Example 3 Using the same toner pulverization raw material as in Example 1, pulverization and classification were performed according to the flowchart of FIG. As a collision-type airflow pulverizer, a pulverizer (pressure 6.0) shown in FIG.
kg / cm ² (G), using compressed air of 6.0 Nm ³ / min), the same coarse powder 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.).

Here, the pulverized raw material was 12.0 kg / hr.
With a weight average particle size of 6.7 μm and a number distribution variation coefficient B of 31.0% (20.2% by number of particles having a particle size of 4.0 μm or less, and a particle size of 8.0 μm or more. 1 particle
2.6% by number is contained. ) Was obtained with a classification yield of 51%. When image evaluation was performed on the obtained medium powder, fog was considerably large, and good image quality was not obtained.

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. As a collision-type airflow pulverizer, a pulverizer (pressure 6.0) shown in FIG.
kg / cm ² (G), using compressed air of 6.0 Nm ³ / min), the same coarse powder 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.). In this embodiment, the supply amount of the pulverized raw material is 5.0 kg /
Although the powder was dropped to hr and pulverized, pulverization with a weight average particle diameter of 6 μm or less could not be performed, and a toner having a desired particle diameter could not be obtained. Table 1 summarizes the results of the above Examples and Comparative Examples.

[0123]

Table 1 Table 1 Pulverization results in Examples and Comparative Examples

[0124]

As described above, according to the production method and production apparatus 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. The generation of granulation can be prevented, and the abrasion of the apparatus can be prevented, and continuous and stable production can be performed. Further, by using the manufacturing method and the manufacturing apparatus of the present invention, the static density having a stable and high image density, good durability and excellent predetermined particle size free from image defects such as fog and poor cleaning can be obtained as compared with the conventional method. The charge image developing toner can be obtained at low cost. Furthermore, small particle sizes (especially 3
〜8 μm) can be effectively obtained.

[0125]

[Brief description of the drawings]

FIG. 1 is a flowchart of the production method of the present invention.

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

FIG. 3 is a schematic diagram showing a specific example of an apparatus system of 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 the impingement airflow pulverizing means in the present invention.

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

FIG. 6 is a sectional view taken along the line AA ′ in FIG. 4;

FIG. 7 is a sectional view taken along the line BB 'in FIG.

FIG. 8 is a sectional view taken along the line CC ′ in FIG. 4;

FIG. 9 is a sectional view taken along the line DD ′ in FIG. 4;

FIG. 10 is a schematic cross-sectional view showing another specific example for implementing the impingement airflow pulverizing means in the present invention.

11 is a sectional view taken along the line GG 'in FIG.

FIG. 12 is a sectional view taken along line HH ′ in FIG. 10;

FIG. 13 is a schematic sectional view of a preferred embodiment of a coarse powder classification means used in the production method and apparatus of the present invention.

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

FIG. 15 is a cross-sectional view of a classification device as a specific example for implementing the multi-division classification means in the present invention.

FIG. 16 is a front view of a conical collision member having a projection in the center.

FIG. 17 is a plan view of a conical collision member having a projection at the center.

FIG. 18 is a flowchart for explaining a conventional manufacturing method.

FIG. 19 is a schematic cross-sectional view of a conventional impingement airflow pulverizer.

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

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. The powder is classified into a coarse powder and a fine powder by a powder classification means, and the classified coarse powder is finely pulverized by an impingement airflow pulverization means to produce a 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 collision-type airflow pulverizing means has an accelerating tube for conveying and accelerating coarse powder supplied by high-pressure gas, and a pulverizing chamber for finely pulverizing the coarse powder; Has a coarse powder supply port for supplying coarse powder into the accelerating tube; A crushing member having a colliding surface provided opposite to the opening surface of the mouth; the crushing chamber has a side wall for further crushing the crushed material of the coarse powder crushed by the colliding member by collision; closest distance 1 ₁ between the edge of the side wall and the collision member is shorter than the closest distance 1 ₂ between the grinding chamber front wall facing the impact surface and the edge of the collision member, in the pulverizing chamber, the collision After crushing the coarse powder and further crushing of the crushed material on the collision surface and the side wall of the member, the fine powder circulated to the coarse powder classifying means is classified into at least two stages by the coarse powder classifying means. A fine powder classifying means, and a final stage fine powder classifying means is a production method which is introduced into a multi-stage fine powder classifying means comprising a multi-divided classifying means which is fractionated into at least three. The group is caused to descend in a curved curve by the Coanda effect, and the third fractionation area has a predetermined particle size or less. The coarse powder mainly composed of the above particle group is divided and collected, and the medium powder mainly composed of the particle group of a predetermined particle size range is divided and collected in the second fractionation area, and the first fractionation area is divided. A fine powder mainly composed of a group of particles having a particle diameter equal to or smaller than a predetermined particle size, and collecting the coarse powder divided by the multi-divided classification means to the crushing means or the coarse powder classification means. The fine powder constituting the multi-stage fine powder classification means
The classification point A of the classification means is as follows: 1.0 <A ₁ <‥‥ <A _n-1 <5.0 (1) 1.5 <A _n <7.0 (2) A ₁ <‥‥ <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). Show what you are doing. n indicates the number of stages of the multistage fine powder classification means. The classification point of the first stage of a multistage fine powder classifying A _1, classification point of the second stage to define a classification point of A _2, n-th stage and A _n. Incidentally, classification point of the final stage of the multi-stage fine powder classifying means, the first fractionation zone and a second
Classification point of the fractionation area. And the weight average particle diameter D _{4 of} the middle powder collected in the multi-stage fine powder classification step is 3 to 8
μm and the variation coefficient B of the number distribution is as follows: 20 ≦ B ≦ 40 (5) [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.