JPH0359674A - Manufacture of toner for electrostatic charge image development - Google Patents

Abstract

PURPOSE:To produce the toner for electrostatic charge image development with a fine grain size distribution efficiently by supplying a raw material of toner powder to a classification zone at a specific speed through a supply nozzle opening, adjusting the absolute value of static pressure nearby the upper ends of a 1st and a 2nd air intake and classifying the raw material under constant conditions. CONSTITUTION:In a multiple-division classification area, the classification area is evacuated through at least one of discharge ports 31 - 33 and the raw material of toner powder is supplied to the classification zone at a flow-side speed of 50 - 300 m/second with air flowing in the raw material supply nozzle 36 by the evacuation. Then the absolute value of static pressure P1 nearly the upper part of an intake 34 is adjusted by the gas introduction adjusting means 20 to >=150 mmaq and the absolute value of static pressure P2 nearby the upper part of an intake 35 is adjusted by the 2nd gas introduction adjusting means 21 to >=40 mmaq so that ¦P1¦-¦P2¦ >= 100, where ¦P1¦ is the absolute value of the static pressure P1 and ¦P2¦ is the absolute value of the static pressure P2. Consequently, a toner product which is particles of a uniform component and has a fine particle size distribution is obtained efficiently.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a manufacturing method for efficiently pulverizing and classifying solid particles having a binder resin to obtain a toner for developing an electrostatic image having a predetermined particle size. Regarding.

[Conventional technology]

In image forming methods such as electrophotography, electrostatography, and electrostatic printing, toners are used to develop electrostatic images.

The process of pulverizing and classifying raw material solid particles to obtain the final product in the production of electrostatic image developing toner, which requires the final product to be fine particles, has conventionally been shown in the flowchart of FIG. method is commonly adopted. The method involves melting and kneading predetermined materials such as a binder resin, coloring agent (dye, pigment, magnetic material, etc.), cooling and solidifying them, and then crushing them.The crushed solid particles are used as the crushed raw material. There is.

The pulverized material is continuously or sequentially supplied to the first classification means and classified, and the classified coarse powder mainly composed of coarse particles having a specified particle size or more is sent to the pulverization means and pulverized again. 1
It is circulated to the classification means.

Other powders whose main components are particles within the specified particle size range and particles whose particle size is less than the specified particle size are sent to the second classification means, where they are divided into medium powder whose main components are particles with the specified particle size and smaller than the specified particle size. It is classified into coarse and fine powder whose main components are particles of For example, if you want to obtain a particle group with a weight average particle size of 10 to 15 μm and 1% or less of particles of 5 μm or less, use an impact crusher or jet crusher equipped with a classification mechanism to remove coarse particles. The raw material is crushed and classified to a predetermined average particle size using a crushing means such as the above, and after removing the coarse powder, the crushed product is passed through another classifier to remove the fine powder to obtain the desired medium powder. There is. The weight average particle diameter is determined by, for example, Coulter Electronics (
This is a method of expressing measurement results using a Coulter counter manufactured in the United States. Hereinafter, the weight average particle diameter will be simply referred to as "average particle diameter."

The problem with such conventional methods is that particles from which coarse particles of a certain particle size or more have been completely removed must be sent to the second classification means for the purpose of removing fine powder; The load on the means increases and the amount of processing decreases. In addition, in order to completely remove coarse particles of a certain particle size or more, over-pulverization is inevitable, resulting in phenomena such as a decrease in yield in the second classification means for removing fine powder in the next step. There is a problem.

As the first classification means, a type of classifier that generates a high-speed swirling vortex flow in the powder supplied to the classification chamber and centrifugally separates the powder into a fine powder group and a coarse powder part is widely and generally used. In such a classifier, when the powder raw material flowing into the classification chamber flows in a swirling manner in the classification chamber, centrifugal force and inward air resistance force act on each particle of the powder raw material, The classification point is determined by the balance between this centrifugal force and air resistance force.

Large particles swirl on the outside of the classification chamber, and small particles swirl on the inside. By forming powder discharge ports at each of the bottom center and the outer periphery of the classification chamber, it is possible to separate and collect (classify) fine powder and coarse powder.

In such an air classifier, it is important for the powder raw material to be sufficiently dispersed and turned into secondary particles in the classification chamber in order to improve the classification accuracy.

As this type of classifier, the Iitani classifier and Classiflon have been proposed. However, with this type of classifier, there were problems in that it was extremely difficult to control the classification point, poor dispersion, and poor classification accuracy at Takamatsu dust concentrations. Various proposals have been made to improve this problem. For example, there are proposals described in JP-A-54-48378 and JP-A-54-79870. An example of a classifier that has been put into practical use is a classifier commercially available under the name of DS separator. In this type of classifier, it has become possible to control the classification point, but since the powder is supplied to the classification chamber via the cyclone section, the powder is concentrated before entering the classification chamber.
There was a tendency for the powder to be insufficiently dispersed. This caused a decrease in classification efficiency. No. 10 in the attached drawings
The conventional device will be further explained with reference to the drawings and FIG.

FIG. 1O is a schematic diagram of the outer surface of the conventional device, and FIG. 11 is a schematic sectional view of the conventional device.

In FIGS. 10 and 11, 1 is a main casing, 2 is a lower casing connected to the lower part of the casing 1, and the lower part is equipped with a hopper 3,
A classification chamber 4 is formed inside the main casing l. A guide tube 10 stands up on the upper part of the main body casing l, and a supply tube 9 is connected to the upper outer peripheral surface of the guide tube 10. A conical (umbrella-shaped) discharge guide plate 15 with a high center is attached to the lower part of the guide tube 10.
An annular supply groove 11 is formed around the outer periphery of the lower edge of 5.

The bottom of the classification chamber 4 is equipped with a conical (umbrella-shaped) classification plate 5 with a high central portion, and an annular coarse powder discharge groove 6 is formed around the lower edge of this classification plate 5. Further, a fine powder discharge lower is formed in the center of the classification plate 5.

A gas inlet 8 for air to flow is provided around the outer circumference of the lower peripheral wall of the classification chamber 4, and this air inlet 8 is normally formed by a gap between a plurality of blade-shaped classification loopers 14. It is configured. The direction of the air introduced from the gas inlet 8 is set by the classification looper 14 so that the air is ejected in the swirling direction of the powder material that descends while swirling in the classification chamber 4.
The rotation speed is adjusted to disperse the powder material and accelerate the rotation speed.

FIG. 5b shows a sectional view taken along line mm in FIGS. 1O and 11. The airflow inlet 8 shown in FIG. 5 is a specific example, and it is also possible to change the shape of the classification looper. The interval between the classification loopers 14 can be adjusted, and by changing this interval, the rotation speed of the powder in the classification chamber 4 can be changed and the classification point can be changed. Further, the height of the classification chamber 4 can also be adjusted. In such a conventional air classifier, the powder raw material is pressure-fed from the supply tube 9 to the guide tube 10 by the airflow, descends while swirling around the inside and outside of the guide tube 10, and enters the classification chamber through the annular supply groove 11. 4. In the classification chamber 4, each particle is centrifugally separated into a coarse powder group and a fine powder group by centrifugal force acting on each particle. However, in conventional devices, the raw material powder is supplied into the classification chamber 4 while being concentrated on the inner wall of the guide cylinder due to centrifugal force, so the dispersion of the powder particles is insufficient, and the powder is similar to the cyclone. Since the material descends in a spiral strip inside the guide tube, the concentration supplied to the classification chamber is uneven depending on the location, and sufficient classification accuracy cannot be obtained. That is, when fine powder forms aggregates or when fine powder is attached to coarse powder, if dispersion is insufficient, the tendency of fine powder to mix into the coarse powder group increases. Furthermore, if the dispersion is insufficient, the dust concentration within the classification chamber 4 will become non-uniform, the classification accuracy itself will deteriorate, and the resulting classified product will have a wide particle size distribution. This tendency becomes more pronounced as the particle size of the powder raw material becomes finer.

Regarding the second classification means for the purpose of removing fine powder, aggregates composed of extremely fine particles may be formed, and it is difficult to remove the aggregates as fine powder. In that case,
The aggregates are mixed into the final product, making it difficult to obtain a product with a precise particle size distribution, and the aggregates disintegrate in the toner to become extremely fine particles, causing deterioration in image quality.

Even if it is possible to obtain a desired product with a precise particle size distribution using the conventional method, the process becomes complicated, causing a decrease in classification yield, resulting in poor production efficiency and high costs. is unavoidable. This tendency becomes more pronounced as the predetermined particle size becomes smaller.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a manufacturing method that solves the various problems described above in conventional methods of manufacturing toner for developing electrostatic images. An object of the present invention is to provide a manufacturing method for efficiently producing an electrostatic image developing toner having a precise particle size distribution.

Another object of the present invention is to provide a method for efficiently producing a high quality toner having a small particle size (for example, 2 to 8 μm).

The purpose of the present invention is to melt-knead a mixture consisting of a binder resin, a coloring agent, and various additives, cool the molten mixture, and then pulverize the resulting solid particles. An object of the present invention is to provide a method for efficiently producing toner (used as a toner) with good yield.

[Summary of the invention]

The method of the present invention uses pulverized material as a raw material, and FIG. 1 is a flow chart showing an overview of the method. In the method of the present invention, the pulverized raw material is supplied to a first classification means for the purpose of removing a coarse powder region, and the classified coarse particles are sent to an appropriate pulverization means, and after being pulverized, they are sent to the first classification means again. be returned. The fine powder from which the coarse particles have been removed is sent to a multi-division classification area where it is classified into at least large particle size classification (coarse powder mainly composed of particles with a specified particle size or more), medium particle size classification (coarse powder whose main component is particles with a specified particle size or more), It is classified into three particle size categories: medium-sized powder (mainly composed of particles), and small particle-sized (fine powder mainly composed of particles with a specified particle size or less). The particles in the large particle size category may be introduced into the first classifying means together with the pulverized raw material, and then pulverized again by the pulverizing means. Further, the particles in the large particle size category and the particle groups in the small particle size category may be recycled to the melting process and reused.

Particle groups of each particle size classification are respectively taken out from the multi-division classification area by appropriate taking out means.

The particles from the medium particle size category have a suitable particle size distribution and can be used as is as a toner.

In view of classification efficiency, the true specific gravity of the powder to be classified is approximately 0.5 to 2.0, preferably 0.6 to 1.7.

For example, as a medium powder, the weight average diameter is 11 μ (particle size 5.04
To obtain a toner powder containing 0.5% by weight of particles with a particle diameter of 20.2μ or more and 0.1% by weight or less of particles with a particle size of 20.2μ or more, which can be considered to be substantially free of particles. In this case, the particle size of the particle group introduced into the multi-division classification means is 20
．． It is preferable to perform the pulverization so that the content of particles of 2μ or more is 15% by weight or less, preferably 3 to 10% by weight, in order to improve the pulverization efficiency and increase the classification yield.

Examples of the first classification means include those shown in FIG. 2 (showing the outer surface of the device) and FIG. 3 (showing a longitudinal sectional front view of the device).

In FIGS. 2 and 3, 1 indicates a main casing, 2 is a lower casing connected to the lower part of the casing l, which is equipped with a hopper 3 at the lower part, and the main casing l has a casing for classification. A chamber 4 is formed. A guide tube 10 stands up on the upper part of the main body casing l, and this guide tube 1
A supply tube 9 is connected to the upper outer periphery of 0. Guide tube 1
A conical (umbrella-shaped) discharge guide plate 15 with a high central portion is attached to the lower part of the discharge guide plate 15, and an annular supply groove ti is formed around the lower edge of the discharge guide plate 15. The bottom of the classification chamber 4 is equipped with a conical (umbrella-shaped) classification plate 5 with a high center. Coarse powder is distributed around the lower edge of the classification plate 5 to discharge an annular group of coarse particles. A discharge groove 6 is formed, and a fine powder discharge lower is formed in the center of the classification plate 5 for discharging the fine powder group. A gas inlet 12 is provided on the outer periphery of the upper peripheral wall of the classification chamber 4 as an air flow inlet means. The means for constructing the gas inlet 12 is not limited, but a preferred example is one constructed by a gap between a plurality of vane-shaped dispersion loopers 13. FIG. 4 shows a sectional view taken along line II in FIGS. 2 and 3. As shown in FIG. 4, the air 16 introduced from the gas inlet 12 descends while swirling around the inside and outside of the guide tube 10, and swirls into the classification chamber 4 through the annular supply groove 11. It is adjusted by the dispersion looper 13 so that it is ejected in the swirling direction of the powder material. The air flow inlet means formed by the looper 13 plays the role of actively dispersing the powder immediately after it has entered the classification chamber 4, reducing the amount of powder aggregates, and further accelerating the powder. This significantly improves the classification accuracy of powder. A gas inlet 8 for introducing air is provided around the outer circumference of the lower peripheral wall of the classification chamber 4. The gas inlet 8 is constituted by a gap between a plurality of blade-shaped classification loopers 14, as shown in FIG. 5a.

The direction of the air 17 introduced from the gas inlet 8 is adjusted by the classification looper 14 so that it is ejected in the swirling direction of the powder material descending while swirling in the classification chamber 4, thereby redispersing the powder material and It is designed to accelerate turning speed.

The intervals between the classification loopers 14 and the intervals between the dispersion loopers 13 can be adjusted, and the heights of the classification loopers 14 and the dispersion loopers 13 can also be set appropriately.

According to the configuration of the present invention, the powder material that is concentrated by centrifugal force on the inner wall of the guide tube 10 and swirls into the classification chamber 4 through the annular supply groove 11 is supplied with air 1 that flows in through the gas inlet 12.
6, the swirling force is accelerated and the swirling force falls to the lower part of the classification chamber, where the swirling force is further accelerated by the air 17 flowing in from the airflow inlet 8.
It is efficiently classified into coarse powder group and fine powder group. This classification room 4
The dispersion state of the powder raw materials inside the container greatly affects the classification performance. In conventional air classifiers, this dispersion is insufficient for highly accurate classification, and the present invention solves this problem by providing a gas inlet 12 at the top of the classification chamber. . The gas inlet 12 provided in the upper part of the classification chamber is preferably provided above the center of the overall height of the classification chamber 4, and is preferably provided below the annular supply groove 11. It is preferable that the wind speed of the air 16 flowing in from the air inlet 12 is adjusted to be equal to or slower than the wind speed of the air 17 flowing in from the air flow inlet 8 at the lower part of the classification chamber.

This is because the main purpose of the air 16 flowing in from the gas inlet 12 is to disperse particles constituting the powder.
On the other hand, the air 17 flowing in from the gas inlet 8 is based on the technical idea that it imparts a strong swirling force to the particles and is introduced in order to classify them into coarse particles and fine particles based on the difference in centrifugal force.

Let A (crtf) be the total opening area of the air inlets 12, and B (crtf) be the total opening area of the air inlets 8, then set the opening area to 1≦−≦20 so that A and B satisfy the following formula. Adjustment is preferable in terms of improving classification performance.

The classifier of the present invention is characterized by having an air inlet in the upper part of the classification chamber, and the configuration of the lower part of the air inlet is not limited to the configuration illustrated in FIGS. 2 and 3.

In the apparatus of the present invention, each particle has a very high tendency to be sufficiently dispersed down to the primary particles in the classification chamber, so the classification efficiency is high, and the particle group classified by the apparatus of the present invention has a precise particle size distribution. There is. Furthermore, in the apparatus of the present invention, it is also possible to make the target separated particle size smaller than in conventional apparatuses.

The air classifier as the first classification means of the present invention is used by being connected to a pulverizer as shown in the flowchart of Fig. 1. In this case, the air classifier of the present invention is supplied with pulverized raw material, and a certain specified particle size is The above coarse powder is introduced into a pulverizer, and after being pulverized, it is circulated through the air classifier again. Particles pulverized to a specified particle size or less are taken out from the air classifier by an appropriate take-out means and sent to a multi-division classification means. In such grinding systems, conventional air classifiers do not fully disperse the powder in the classification chamber, so they completely remove aggregates made up of ultrafine particles or fine particles attached to coarse powder. It is difficult to loosen the aggregates, and such aggregates enter the coarse pigeon group during classification and are circulated back to the crusher, which tends to cause over-grinding and reduce the crushing efficiency.

In order to solve this problem, in the active flow classification device of the present invention, the particles in the dispersion chamber are sufficiently dispersed, so that such aggregates can be loosened, preventing them from being mixed into the coarse powder group, and forming fine particles. Since the particles are removed as fine powder, the pulverization efficiency can be further improved.

The effect of the classification device of the present invention is more pronounced as the particle size of the powder becomes smaller and as the dust concentration in the classification chamber becomes higher.
It is effective in the following areas, as in the present invention.

It is more effective when combined with a crusher.

As the means for providing the multi-divided classification area, for example, the sixth
A multi-division classifier of the type shown in FIG. 7 (cross-sectional view) and FIG. 7 (stereoscopic view) can be exemplified as one specific example. In FIGS. 6 and 7, the side wall has the shape shown at 22.24, the bottom wall has the shape shown at 25, and the side wall 23 and the bottom wall 25 each have a knife-etched classification edge 37. ，
18, and this classification edge 37. 18, the classification zone is divided into three parts. A raw material supply nozzle 36 opening into the classification chamber is provided below the side wall 22, and a Coanda block 26 is provided which is bent downward in the direction of extension of the bottom tangent of the nozzle to draw an elongated arc. Classification room upper wall 2
7 is the popular knife-etched edge 1 towards the bottom of the classification chamber.
9, and the upper part of the classification chamber is provided with popular pipes 34 and 35 that open into the classification chamber. In addition, the popular pipes 34 and 35 have first dampers like dampers. Second gas introduction adjustment means 20.21
and static pressure gauges 28 and 29 are provided. Classification edge 37.
The positions of 18 and the popular edge 19 vary depending on the type of raw material to be classified and the desired particle size. Further, on the bottom of the classification chamber, there are discharge ports 31 that open into the chamber corresponding to each fractionation area. 32°33 is provided. Discharge port 31
, 32 and 33 may each be provided with opening/closing means such as valve means.

The raw material supply nozzle 36 has a right-angled cylinder part and a square cylinder part,
The ratio of the inner diameter of the right-angled cylinder part to the inner diameter of the narrowest part of the square cylinder part is 20:1 to 1:11, preferably 1o:1 to 2=1.
Setting it to gives good introduction speed.

The classification operation in the multi-division classification area configured as described above is performed as follows. i.e. outlet 31.32.3
The pressure inside the classification zone is reduced through at least one of the following:
The toner powder raw material is supplied to the classification area through the raw material supply nozzle 36 at a speed of 7 seconds, and the absolute value of the static pressure PI near the upper part of the inlet port 34 is 150 m m a 4 or more, preferably 20 m m a 4 or more.
The absolute value of the static pressure P2 near the upper part of the popular port 35 is adjusted by the first gas introduction adjusting means 20 so that it is 0 mm a 4 or more, and preferably 45 to 7.
It is adjusted by the second gas introduction adjustment means 21 so that it becomes 0 mm a p, and it is adjusted so that the absolute value 1p+1 of the static pressure P and the absolute value IP21 of the static pressure P2 are expressed by the following formula 1. The absolute value of static pressure P2 is 45 to 7
A range of 0 m m aq is preferable because fine powder and coarse powder are dispersed more widely within the classification area, making it easier to adjust the classification point.

When Pl and P2 become IF 11 1P 21 < 100, the classification accuracy decreases, it becomes impossible to precisely remove the fine powder region, and the resulting product becomes a classified product with a wide particle size distribution. Furthermore, if the toner powder raw material is supplied to the classification zone at a flow rate of 50 m/sec or less, the agglomeration of the toner powder raw material cannot be sufficiently loosened, resulting in a decrease in classification yield and classification accuracy. Furthermore, if the toner powder raw material is supplied to the classification zone at a flow rate of 300 m/sec or more, the particles will be crushed due to collisions between the powders, producing fine particles, which tends to cause a decrease in the classification yield.

The supplied toner powder raw material moves in a curved line 30 due to the Coanda effect, due to the action of the Coanda block 26 and the action of gas such as air flowing in, and moves according to the size and weight of each particle. and are classified. Assuming that the specific gravity of the particles is the same, large particles (coarse particles) are classified into the first fraction outside the airflow, that is, on the left side of the classification edge 18, and intermediate particles (particles with a particle size within the specified range) are classified into the classification edge 18. They are classified into the second fraction between 18 and 37, and small particles (particles with a specified particle size or less) are classified into the third fraction on the right side of the classification edge 37.
It is classified into fractions. The classified large particles are discharged from the outlet 3I.
intermediate particles are discharged from the discharge port 32,
Small particles are discharged from the discharge ports 33, respectively. Second
It is preferable to adjust the classification conditions so that the average particle size of the particles classified into the fractionation area is about 1-15 μm.

In order to carry out the above-mentioned method, it is usual to use an integrated device system in which mutual devices are connected through communication means such as pipes, and a preferred example of such a device is shown in Section 8.
As shown in the figure. The integrated device shown in FIG. 8 is a three-part classifier 10.
1 (of the type shown in FIGS. 6 and 7. Details are as explained above), quantitative feeder 102, quantitative feeder 110, vibration feeder 103, collection cyclone 1
04, collection cyclone 105, collection cyclone lO6,
Collection cyclone 107, crusher 108, first classifier 1 (
The type shown in FIGS. 2 and 3) is connected to a communication means.

In this device, the so-called toner powder raw material is introduced into the first classifier 1 via a quantitative feeder 102, and the fine powder from which the coarse powder region has been removed is sent to the quantitative feeder 110 via a collection cyclone 107. Next, the vibration feeder 103
3-divided classifier 101 via raw material supply nozzle 36
be introduced within. The coarse powder particles classified by the first classifier 1 are sent to the crusher IO8, where they are crushed, and then introduced into the first classifier 1 again together with the newly introduced crushed raw material. When introducing the pulverized material into the three-part classifier 101, the suction force of the collection cyclones 104, 105 and/or 106 is used to suction and introduce the pulverized material at a flow rate of 50 to 300 m for 7 seconds.

・i The size of the classification area of the classifier 101 is usually (10~
50cm] x [10~50cm], so the crushed material is 0.
It is possible to instantly classify particles into three or more types of particle groups within 1 to 0.01 seconds. Then, the three-part classifier 101 divides the particles into large particles (particles with a specified particle size or more), intermediate particles (particles with a particle size within the specified range), and small particles (particles with a specified particle size or less). Thereafter, the large particles may be returned in this flow through the discharge conduit 31 via the collection cyclone 106 to the metering machine 102 holding the ground material.

The intermediate particles are discharged out of the system via discharge conduit 32 and collected by collection cyclone 105 to be recovered as toner product 51. The small particles are discharged out of the system via the discharge conduit 33, collected by the collection cyclone 104, and then collected as microparticles 41 having an irregular particle size. Collection cyclone 104. 105. 106 is the nozzle 3 for the pulverized raw material.
It functions as a suction pressure reducing means for suctioning and introducing the liquid into the classification area via the tube 6.

As the crusher 108, crushing means such as an impact crusher or a jet crusher can be used. Examples of impact type crushers include Turbo Mill manufactured by Turbo Kogyo Co., Ltd., and examples of crushers using jets include supersonic jet mill PJM-1 manufactured by Japan Pneumatic Industries, Micron Jet manufactured by Hosokawa Micron Co., Ltd., and the like.

The multi-division classifier in the method of the present invention has a Coanda block such as the Elbow Jet manufactured by 8 Iron Mining Co., Ltd.
One example is a classification method using the Coanda effect.

In the conventional pulverization-classification method that uses a classifier for the purpose of removing only fine particles as the second classification means, coarse particles having a specified particle size or more are completely removed at the particle size of the powder at the end of pulverization. It was required to be there. Therefore, a grinding capacity higher than necessary is required in the grinding process, resulting in over-pulverization and a decrease in grinding efficiency.

However, as explained above, the method of the present invention can simultaneously remove coarse powder particles and fine powder particles using a specific multi-division classification means.

Therefore, even if the particle size of the powder at the end of grinding contains a certain proportion of coarse particles with a specified particle size or higher, they will be completely removed by the multi-division classification means in the next step, so there are no restrictions in the grinding process. As a result, the capacity of the pulverizer can be maximized, resulting in better pulverization efficiency and less tendency to cause over-pulverization.

Therefore, the fine powder region can be removed very efficiently, and the classification yield can be favorably improved.

Conventional classification methods for classifying medium-powder areas and fine-powder areas tend to produce agglomerates of fine particles that cause fogging in developed images. When aggregates occur, it has been difficult to remove them from the medium-sized powder region, but according to the method of the present invention, even if aggregates are mixed into the pulverized material, the Coanda effect and/or the impact caused by high-speed movement can be avoided. The aggregates are broken up and removed as fine powder, and even if there are aggregates that have escaped disintegration, they can be simultaneously removed to the coarse powder region, making it possible to efficiently remove the aggregates.

Furthermore, according to the method of the present invention, the powder is sufficiently dispersed in the first classification means, and the resulting pulverized product has a fine particle size distribution, so that the final medium powder can be obtained with a high yield. be able to.

Usually, toner for developing electrostatic images is styrene-based resin.

Binder resin such as styrene-acrylic acid ester resin, styrene-methacrylic acid ester resin, polyester resin, colorant (or/and magnetic material), anti-offset agent,
After melting and kneading raw materials such as a charge control agent, cooling and pulverization 9
Manufactured by classification. At this time, since it is difficult to obtain a melt in which each raw material is uniformly dispersed in the kneading process, the crushed material may contain particles unsuitable as toner particles (for example, containing colorants or magnetic particles). There are some particles that do not exist or individual particles of various raw materials). In the conventional pulverization and classification method, the residence time of the particles is long during the pulverization and classification process, which makes it easy for unsuitable particles to aggregate, and it is difficult to remove the resulting agglomerates. As a result, the characteristics of the toner have deteriorated.

Since the method of the present invention instantly classifies into 3 or more fractions after pulverization, it is difficult to produce the above-mentioned aggregates, and even if they occur, it is possible to remove the aggregates to the coarse powder region, so that particles with uniform components can be obtained. It is possible to obtain a toner product with a precise particle size distribution.

The toner obtained by the method of the present invention has a stable amount of triboelectric charge between toner particles or between a toner and a toner carrier such as a sleeve or a toner and a carrier. Therefore, development fog and toner scattering around the etch of the latent image are extremely reduced, high image density is obtained, and halftone reproducibility is improved.

Furthermore, even when the developer is used continuously for a long period of time, the initial characteristics can be maintained and high quality images can be provided for a long period of time. Furthermore, even when used under environmental conditions of high temperature and high humidity, the amount of triboelectric charge of the developer is stable because there are few ultrafine particles and their aggregates, and there is almost no change compared to normal temperature and humidity, so there is no fogging. Development that is faithful to the latent image can be performed with little decrease in image density. Furthermore, the obtained toner image has excellent transfer efficiency to a transfer material such as paper. Even when used under low-temperature conditions, the triboelectric charge distribution is almost the same as that at room temperature and humidity, and because the ultrafine particle components of the toner, which have an extremely large charge amount, have been removed, there is no decrease in image density or fog, and there is no roughness. The toner obtained by the method of the present invention has the characteristic that there is almost no scattering during transfer.

When producing a medium powder with a small particle size (for example, an average particle size of 3 to 7 microns), the present invention can be carried out more efficiently than conventional methods.

Hereinafter, the present invention will be described in detail based on Examples.

Incidentally, the particle size distribution shown in the examples was measured using a Coulter counter.

[Example 1] A toner raw material consisting of a mixture of the above formulation was melted and mixed in a roll mill at about 180° C. for about 1.0 hours, and then cooled and solidified.
It was ground to particles of 100-1000μ in a hammer mill.

The obtained pulverized material was introduced into the classifier shown in FIGS. 2 and 3, and classified based on the classifier system shown in FIG. 8.

The crusher used was a supersonic jet mill model I-5 manufactured by Nippon Pneumatic Kogyo Co., Ltd., and the air classifier 1 was of the type shown in Figures 2 and 3. / m
Suction is carried out at an air volume of t
x0.2 I made it 12cm. 20k per hour
The raw materials were supplied at a ratio of 1.5 g, and the raw materials were pulverized to a specified particle size or less and sent to the cyclone 107 as fine powder.

Sampling was carried out at the bottom of cyclone 107, and the particle size of the fine powder was measured. The weight average diameter was 11.2 μm (containing 5.0% by weight of particles with a particle size of 5.04 μm or less, and particles with a particle size of 20.2 μm or more). The coarse powder (containing 0.5% by weight) was finely classified.

This fine powder is fed to a quantitative feeder 110 and a vibration feeder 10.
Figure 6 through 3 at a rate of 20 kg per hour.

It was introduced into a multi-division classification apparatus 101 shown in FIG. Elbow jet EJ-5-3 type machine (8
(manufactured by Iron Mining Co., Ltd.) was used.

At the time of introduction, a collection cyclone 104. The pulverized material is introduced into the supply nozzle 36 at a flow rate of about 100 m/sec by the suction force derived from the reduced pressure in the system due to the suction reduced pressure of 105 and 106, and the static pressure P1 above the popular port 34 is reduced to -290 m m aq %.
The static pressure P2 above the popular port 35 was adjusted to -70 mm aq. The introduced pulverized material was instantly classified within 0.01 seconds. The collection cyclone 105 that collects the classified medium powder has a weight average diameter of 12.0 μm (particle size of 5.04 μm).
A medium powder suitable as a toner containing 0.3% by weight of the following particles, and the content of particles with a particle size of 20.2 μm or more is 0.1% by weight or less and can be considered to be substantially free of particles. The fraction was obtained with a classification yield of 85% by weight.

The classification yield here refers to the ratio of the amount of the finally obtained medium powder (product) to the total amount of the supplied pulverized raw material. When the obtained medium powder was observed under an electron microscope, substantially no aggregates of about 5 μm or more, which were ultrafine particles aggregated, were found.

The classified coarse powder was collected by a collection cyclone 6 and then introduced into a quantitative feeder 2.

The obtained medium powder was used as a toner, and hydrophobic silica 0
．． A developer was prepared by mixing 3% by weight, and the developer was transferred to the copier NP-2.
When a copying test was carried out using a developer adjusted to 70RE (manufactured by Canon), a copy image with no fog and good fine line developability was obtained.

[Example 2] A toner raw material consisting of a mixture of the above formulation was melt-kneaded at about 180° C. for about 1.0 hours in a roll mill, and then cooled and solidified.
It was ground to particles of 100-1000μ in a hammer mill.

The obtained pulverized material was introduced into the classifier shown in FIGS. 2 and 3, and classified based on the classifier system shown in FIG. 8.

The crusher used was a supersonic jet mill model I-5 manufactured by Nippon Pneumatic Kogyo Co., Ltd., and the air classifier l was of the type shown in Figures 2 and 3, and the crusher was 1 Orrr/m.
The gas inlet at the top of the classification chamber has two vertical air inlets.
cm and 0.2 cm wide (total opening area 2 x 0.2 Total opening area 2X0.I X20=4c
rrf), and the height of the classification chamber was 12 cm. 1
Cyclone 107 supplies raw materials at a rate of 15 kg per hour and pulverizes them to below the specified particle size as fine powder.
Sent to.

Sampling was performed at the bottom of cyclone 107, and the particle size of the fine powder was measured. The weight average diameter was 7.4 μm (containing 15.0% by weight of particles with a particle size of 5.04 μm or less, and particles with a particle size of 12.7 μm or more). The coarse powder (containing 1.4% by weight) was finely classified.

This fine powder is fed to a quantitative feeder 110 and a vibration feeder 10.
Figure 6 through 3 at a rate of 15 kg per hour.

It was introduced into a multi-division classification apparatus 101 shown in FIG. Elbow jet EJ-5-3 type machine (8
(manufactured by Iron Mining Co., Ltd.) was used.

When introducing the outlet 31. The pulverized material is introduced into the supply nozzle 36 at a flow rate of about 100 m/sec by the suction force derived from the reduced pressure in the system due to the suction reduced pressure of the collection cyclones 104, 105, and 106 communicating with 32. The static pressure P1 at the top is -290 m m aq.

The static pressure P2 above the popular port 35 was adjusted to -70 mmaq. The introduced pulverized material was instantly classified within 0.01 seconds. Collection cyclone 105 that collects classified medium powder
has a weight average diameter of 8.0 μm (contains 6.5% by weight of particles with a particle size of 5.04 μm or less, and the content of particles with a particle size of 12.7 μm or more is 0.1% by weight or less, and substantially A medium powder suitable as a toner was obtained with a classification yield of 80% by weight.

The classification yield here refers to the ratio of the amount of the finally obtained medium powder (product) to the total amount of the supplied pulverized raw material. When the obtained medium powder was observed under an electron microscope, substantially no aggregates of about 5 μm or more, which were ultrafine particles aggregated, were found.

The classified coarse powder was collected by a collection cyclolon 6 and then introduced into a quantitative feeder 2.

[Comparative Example 1] A pulverized product obtained in the same manner as in Example 1 was classified using a pulverization and classification system configured as shown in FIG.

The crusher used was a supersonic jet mill model I-5 manufactured by Nippon Pneumatic Industries Co., Ltd., and the type shown in Figures 10 and 11 was used as the first classification means, and the crusher was 10rd/m i
Suction is carried out at an air volume of n, and the gas inlet at the bottom of the classification chamber is vertically 2c.
The classification chamber was set at 20 locations with a width of 0.2 cm and a height of 8 cm.

Raw materials were fed at a rate of 20 kg per hour. When the particle size of the obtained fine powder was measured, the weight average diameter was 12.0μ.
m (contains 7.0% by weight of particles with a particle size of 5.04 μm or less and 4.0% by weight of particles with a particle size of 20.2 μm or more) with a wide distribution on the coarse powder side. .

This fine powder was introduced into a second classification means and classified into medium powder and fine powder. As the second classification means, DS5UR manufactured by Nippon Pneumatic Kogyo Co., Ltd. was used.

The obtained medium powder had a weight average diameter of 12.8μ (particle size 5.04μ).
Contains 0.5% by weight of particles smaller than μm, particle size 20.2μ
This sample contained 5.0% by weight of particles with a particle size of m or more) and was obtained with a classification yield of 70% by weight, and was inferior to Example 1 in terms of production efficiency.

In addition, when viewed with an electron microscope, it was found that the ultrafine particles were aggregated.
Scattered aggregates larger than μ were found.

The obtained medium powder was used as a toner, and hydrophobic silica 0
．． A developer was prepared by mixing 3% by weight with the toner, and a copying test was conducted by supplying the prepared developer to a copying machine NP-270RE (manufactured by Canon). There was also a lot of fog, and the image was rough.

[Comparative Example 2] A pulverized product obtained in the same manner as in Example 2 was classified using a pulverization and classification system configured as shown in FIG.

The crusher used was a supersonic jet mill model I-5 manufactured by Nippon Pneumatic Kogyo Co., Ltd., and the type shown in FIGS. 10 and 11 was used as the first classification means. / m
The gas inlet at the bottom of the classification chamber has two vertical
The classification chamber was set at 20 locations, each measuring 0.1 cm wide and 0.1 cm wide, and the height of the classification chamber was 8 cm.

Raw materials were fed at a rate of 15 kg per hour. When the particle size of the obtained fine powder was measured, the weight average diameter was 8.3 μm.
(Containing 17.0% by weight of particles with a particle size of 5.04 μm or less and 6.2% by weight of particles having a particle size of 12.7 μm or more) had a wide distribution on the coarse powder side.

This fine powder was introduced into a second classification means and classified into medium powder and fine powder. As the second classification means, DS5UR manufactured by Nippon Pneumatic Kogyo Co., Ltd. was used.

The obtained medium powder had a weight average diameter of 8.5μ (particle size 5.04μ).
(contains 9.8% by weight of particles with a particle diameter of 12.7 μm or less and 7.5% by weight of particles with a particle size of 12.7μ or more) and has a classification yield of 68
% by weight, and the production efficiency was inferior to that of Example 2.

In addition, when viewed with an electron microscope, it was found that the ultrafine particles were aggregated.
Scattered aggregates larger than μ were found.

[Brief explanation of drawings]

In the accompanying drawings, FIG. 1 is a flowchart for explaining the manufacturing method of the present invention, and FIGS. 2 and 3 are diagrams showing the outside of the classification device, which is an example of an integrated body for implementing the first classification means of the present invention. Showing a schematic diagram of the surface and a schematic vertical front view,
Figure 4 shows the knee I cross section in Figure 3, and Figure 5a.
The figure is a sectional view taken along ■--■ in FIG. 3, FIG. 5b is a cross-sectional view taken along ■--■ in FIG. 11, and FIGS. 8 is a schematic diagram showing a classifier system for implementing the manufacturing method of the present invention, and FIG. 9 is a schematic diagram showing a classification device system for carrying out the manufacturing method of the present invention. A flowchart for explanation is shown, and FIGS. 10 and 1
FIG. 1 shows a schematic diagram of the outer surface and a schematic longitudinal sectional front view of a conventional air classifier. 1...Body casing 2...
・・・・・・・・・Lower casing 3・・・・・・・・・
・・・・・・・・・Hopper 4・・・・・・・・・・・・
・・・・・・・・・Classification room 5・・・・・・・・・・・・・・・
・・・・・・Classifying plate 6・Pa・・・・・・・Coarse powder discharge groove 7・・・・・・・・・・・Fine powder discharge chute 8・・・・・・・・・...Gas inlet 9...
・・・・・・・・・・・・・Supply cylinder 10・・・・・・
・・・・・・・・・Guide tube 11・・・・・・・・・・
...... Supply groove 12 ......
・Gas inlet 13...Dispersion looper 14...Classification looper 15...
・・・・・・・・・・・・・・・ Information board 18, 37...
・・・・・・・・・Classification Edge 19・・・・・・
...Inlet edge 22゜28゜31゜34゜First gas introduction adjustment means Second gas introduction adjustment means 23, 24...Side wall lower wall Coanda block upper part Wall 29... Static pressure gauge Solid particle scattering direction 32, 33... Outlet port 35...
・・・・・・・・・・・・Inlet raw material supply nozzle・・・・・・・・・・・・Three division classifier Quantitative feeder Vibration feeder Collection Cyclone collection Cyclone collection Cyclone collection Cyclone crusher quantitative feeder 2

Claims (1)

[Claims] (1) Melt and knead a composition containing at least a binder resin and a colorant, cool and solidify the kneaded material, crush the solidified material to generate a pulverized raw material, and classify the generated pulverized raw material to produce toner powder. In the manufacturing method, the pulverized raw material is introduced into the first classification means to be classified into coarse powder and fine powder, and the classified coarse powder is introduced into the pulverization means and pulverized, and then circulated to the first classification means and classified. The resulting fine powder is introduced into a multi-division classification means in which it is divided into at least three parts by a fractionation means, and the particle group is caused to descend in a curved line due to the Coanda effect, and particles with a predetermined particle size or more are introduced into the first fractionation area. Coarse powder mainly composed of particle groups is divided and collected, medium powder mainly composed of particles within a predetermined particle size range is divided and collected in a second fractionation area, and a predetermined amount is collected in a third fractionation area. In a method for producing toner powder by dividing and collecting fine powder mainly composed of particles having a particle size or smaller, the first classifying means forms a supply port in an upper part of the classification chamber for supplying the powder. The lower part of the classification chamber is equipped with a conical classification plate with a high central part, and a coarse powder outlet for discharging coarse powder is provided around the lower edge of the classification plate. A fine powder outlet for discharging the fine powder group is provided in the center of the classification plate, and a gas inflow means is provided for dispersing the powder around the upper outer periphery of the classification chamber by a swirling flow of gas. This air classifier is equipped with a gas inlet at the bottom of the classification chamber to generate a swirling flow of gas for classifying powder, and the multi-division classification means is used to classify coarse powder. A first discharge port for discharging the classified coarse powder into the medium powder region, a second discharge port for discharging the classified medium powder into the medium powder region, and a third discharge port for discharging the classified fine powder into the fine powder region. The pressure inside the classification zone is reduced through at least one of the discharge ports, and the toner powder is produced at a flow rate of 50 m/s to 300 m/s by the air flow caused by the reduced pressure in a supply pipe having a supply nozzle opening opening into the classification region. The raw material is supplied to the classification zone through the supply nozzle port, and a first opening to the classification zone is provided on the side closer to the supply nozzle port.
The first gas introduction adjusting means adjusts the absolute value of the static pressure P_1 near the upper part of the first gas introduction port in the first gas introduction pipe having the gas introduction port to be 150 mmaq or more, and the first gas is supplied from the supply nozzle port. The second gas is introduced so that the absolute value of the static pressure P_2 near the upper part of the second gas inlet in the second gas inlet pipe having the second gas inlet opening into the classification area on the side farther from the inlet is 40 mmaq or more. The absolute value of static pressure P_1 |P_1| and the absolute value of static pressure P_2|
A method for producing a toner for developing an electrostatic image, characterized in that the classification is carried out under conditions where P_2| satisfies the following formula |P_1|-|P_2|≧100.