JPH09187733A - Air current-utilizing type classifying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a precise classifying point corresponding to the values of characteristic physical properties of a raw material powder and efficiently obtain a classified powder product in a sharp distribution of particle size by whirling and streaming high pressure air and making a Coanda diameter of a Coanda block changeable corresponding to the values of the physical properties of the raw material powder. SOLUTION: High pressure air which becomes a whirling current by leading air out of a leading path 43 is introduced into a raw material supplying nozzle 16 from a high pressure air supplying nozzle 41 and a raw material powder is carried in the raw material supplying nozzle 16 together with the whirling current having high dispersing function and introduced into a classifying region 30. A Coanda ribbon 26 is so installed as to make the powder particles which are led in the vertical direction successively from a lower part of the raw material supplying nozzle 16 draw a long elliptical arc. Since the Coanda ribbon 26 is formed like a kind of a ribbon, it is easy to move the Coanda ribbon 26. Consequently, the Coanda diameter of a Coanda block can be changed optionally, so that the optimum curving current corresponding to the values of characteristic physical properties of a raw material powder of, for example, a toner can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airflow classifier for classifying raw material powders by utilizing the Coanda effect, and a toner manufacturing method using the classifier. In particular, the present invention
In order to efficiently classify fine powder containing particles having a weight average particle diameter of 10 μm or less in an amount of 50% by number or more, carry powder having strong cohesiveness to a swirling airflow having strong dispersive force and carry it to the classification region.
In the classification area, utilizing the Coanda effect, an inertial force according to the particle size of each particle in the powder, an air flow type classification device capable of efficiently classifying into a particle group having a predetermined particle size based on the difference in centrifugal force, etc. The present invention relates to a method for producing a toner for developing an electrostatic charge image using the apparatus.

[0002]

2. Description of the Related Art Conventionally, airflow type classifying devices of various methods have been proposed for classifying powders. Among them, classifiers using rotary blades and classifiers having no moving parts are known. Has been. As a classifier having no moving parts, there are a fixed-wall centrifugal classifier and an inertial force classifier. As a classifier utilizing inertial force, Loffier. F. and K.
Maly: Symphony Powder Techn
D. 2 (1981), an elbow jet classifier commercialized by Nippon Steel Mining Co., Ltd., and Okuda.
S. and Yasukuni. J. Proc. Int
er. Symosium on Powder Tec
The classifier exemplified by hn '81, 771 (1981) is known as an inertial force classifier capable of classifying in a fine powder region.

In these air flow type classifiers, as shown in FIG. 6, powder is jetted into the classifying chamber 32 at high speed from a supply nozzle 116 having an opening in a classifying region 30 of a classifier chamber 32. In the classification chamber 32, for example, the powder is separated into three types of groups of coarse powder, medium powder, and fine powder by the centrifugal force of the curved airflow flowing along the Coanda block 126 in the classification region 30, and the tip becomes thin. Classification edge 117 and 118
Thus, classified products of coarse powder, medium powder and fine powder are obtained.

In the conventional air flow type classifying apparatus 101 described above, when the raw material powder is introduced into the classifying chamber 32 from the pyramidal cylindrical raw material supplying nozzle 116 connected to the raw material introducing nozzle 34, the raw material supplying nozzle 116. The powder that interlocks inside is
It has a tendency to flow with propulsive force in a straight line parallel to the tube wall arranged horizontally. However, as shown in FIG. 6, when the raw material powder is introduced from the upper portion of the raw material accelerating nozzle 34, the powder flow is roughly divided into an upper flow and a lower flow, and the upper flow contains a lot of light fine powder. Contained,
A large amount of heavy coarse powder is likely to be contained in the lower stream, and since each particle flows independently, each particle draws a different trajectory depending on the introduction site into the classifier and the coarse powder traces a fine powder trajectory. Due to the disturbance, the conventional airflow classifying apparatus 101 has a limit in improving the classification accuracy. Especially 20 μm
In the case of classifying the raw material powder containing a large amount of coarse particles, there is a tendency that the classification accuracy is remarkably lowered.

Further, in recent years, in order to improve image quality in copying machines and printers, toner particles used therein tend to be gradually miniaturized. Generally, as the substance becomes finer, the action of interparticle force increases. However, the same applies to resin particles and toner particles, and when the substance has a small size, the cohesiveness between particles increases. When such toner particles having a strong cohesive force are classified by the conventional airflow classifier 101 as described above, sufficient dispersion with respect to the raw material powder cannot be obtained in the raw material supply nozzle 116, resulting in high accuracy. It sometimes happens that a classified product cannot be obtained. That is, there occurs a phenomenon in which particles having a size that should originally be uniform are mixed with particles having a size that should be in another particle group. In particular, since the particles are not sufficiently dispersed in the raw material supply nozzle 116, the particles that should originally be in the fine powder group or the medium powder group are mixed into the coarse powder group, resulting in a decrease in classification efficiency and classification. There was a problem of causing a decrease in accuracy.

Further, in the conventional airflow classifying device 101,
As shown in FIG. 6, since the Coanda diameter of the Coanda block 126 is fixed, a Coanda diameter that is a physical property value specific to the raw material powder, particularly, a Coanda diameter according to the density, particle size, or powder cohesiveness is realized. However, there was a problem that the classification efficiency and the classification accuracy were poor. That is, when classifying particles having a large density and a large inertial force, the Coanda block 12
In the case of classifying powders such as low-density particles and micro-sized particles that are difficult to apply an inertial force, the curved flow is separated from No. 6 and a stable flow cannot be obtained. Since the ejection distance of No. 1 was short, the classification area 30 was extremely narrow, and in any case, it was impossible to perform accurate classification.

In particular, in the classification step of classifying toner fine particles having a high cohesive property, which is carried out when manufacturing a toner for developing an electrostatic charge image used in a copying machine, a printer or the like, such a problem is likely to become apparent. In view of the above points, in particular,
There is a demand for the development of an airflow classifier capable of classifying a fine powder raw material such as toner in a stable, efficient and accurate manner.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an airflow classifying apparatus which solves the above-mentioned problems of the prior art and a toner manufacturing method for manufacturing an electrostatic image developing toner using the apparatus. To do. The object of the present invention is to enable to set an accurate classification point according to the physical property value of the raw material powder, to enable more accurate classification, and to efficiently provide a powder classified product having a sharp particle size distribution. An object of the present invention is to provide an airflow classifier obtained and a method for producing a toner for developing an electrostatic charge image using the apparatus.

[0009]

The above objects are achieved by the present invention described below. That is, the present invention, at least in the classification area formed by the Coanda block and a plurality of classification edges, the raw material powder supplied from the raw material supply nozzle is at least a coarse powder group, a medium powder group and a fine powder group by the Coanda effect. Air flow type classifying device for classifying, a raw material supply nozzle, a raw material powder introduction nozzle and a high pressure air supply nozzle are arranged above the classifying chamber of the device, and the shape of the classification area in the classification chamber can be changed. In such an air flow type classifying device in which the classifying edge is rotatable and the position of the classifying edge block provided with the classifying edge is movable, high pressure air ejected from the high pressure air supply nozzle Is configured to swirl and flow, and the Coanda diameter of the Coanda block can be changed according to the intrinsic physical property value of the raw material powder. Air classifier, and a toner production method which is characterized in that it has a classification step using the device.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. In the airflow-type classification device and the toner manufacturing method of the present invention, a high-pressure air for generating an airflow for carrying the toner particles is prepared so that the raw material powder such as the toner particles which goes to the classification area together with the airflow can be sufficiently dispersed. In order to increase the shearing property and enhance the toner dispersion force, the high-pressure air is made to swirl by means such as providing an inlet passage for swirling the air into the upstream side of the high-pressure air supply nozzle. Thus, in the raw material supply nozzle, by imparting a sufficient dispersive force to the raw material powder such as toner fine particles whose cohesive force has recently increased, it is possible to perform highly accurate classification in a stable state at all times. To do.

Further, in the airflow type classifying apparatus of the present invention having the above-mentioned structure, first, the classifying edge is not only rotatable as in the conventional apparatus, but also the classifying edge provided with this classifying edge. By making the position of the block movable, the shape of the classification area can be changed significantly compared to the conventional apparatus, and the shape of the classification area more suitable for each raw material powder can be realized. In addition to this, the Coanda block is made of an elastic metal such as aluminum or copper and has a thickness of several mm and several c.
The raw material is formed by a kind of ribbon-like band member having a width of m to several tens of cm (hereinafter referred to as a Coanda ribbon), and is configured so that the Coanda diameter of the Coanda block can be appropriately changed. It is possible to form a classification area that can efficiently perform highly accurate classification in a stable state at all times without being affected by the inherent physical properties such as the density, particle size, and powder agglomeration of the powder. . That is, for example, when classifying particles having a large density and a large inertial force, by setting the Coanda diameter larger than the conventional one, it is possible to suppress the separation of the curved air flow from the Coanda arc of these particles and to stabilize particles. On the other hand, when classifying powders that are difficult to apply inertial force such as low density and small size particles, it is possible to obtain a flow by setting the Coanda diameter smaller than before so that the classification range becomes smaller. It spreads to the arc side and enables highly accurate classification in a stable state at all times, and in each case, a high-quality classified product can be obtained.

The present invention will be described below in more detail with reference to the accompanying drawings. As a specific example of the airflow classifying device of the present invention, a device of the type shown in FIGS. 1 to 4 will be cited and explained based on this. FIG. 1 is a schematic sectional view, FIG. 2 is a three-dimensional view of a classifying section, FIG. 3 is a horizontal sectional view of a high-pressure air swirl introducing path section, and FIG. 4 is an enlarged view of a classifying chamber section. Figure 1,
2, 3, and 4, the side walls 22 and 23 form a part of the classification chamber 32, and the tip ends of the classification edge blocks 24 and 25 that also form a part of the classification chamber 32. Sharp classification edges 17 and 18 are provided respectively. In this example, the classification area 30 in the classification chamber 32 is divided into three by the classification edges 17 and 18. The classification edges 17 and 18 are configured to be rotatable around the shafts 17a and 18a, and the tip positions of the classification edges 17 and 18 can be changed at positions along the arc by rotating these. Further, in this example, the set positions of the classification edge blocks 24 and 25 are configured to be slidable vertically with a width of 0 to 50 mm, as shown in FIG. Therefore, the positions of knife-edge type classification edges 17 and 18 provided in the classification edge blocks 24 and 25, respectively, also slide up and down. Therefore, in the airflow type classification device of the present invention, the classification edges 17 and 18
It is possible to significantly change the shape of the classification area 30 formed by the method as compared with the conventional apparatus. The classification edge blocks 24 and 25 may be movable left and right.

Further, a block 33 provided on the left side of the classification chamber 32 is provided with a knife-edge-type rotatable intake air edge 19 toward the classification chamber 32. The position can also be adjusted appropriately. In the air stream classifying apparatus of the present invention, the positions of the air intake edge 19 and the classification edges 17 and 18 described above are appropriately set with a considerable degree of freedom depending on the kind of the toner particles as the raw material to be classified and the desired particle size. Since it is possible to adjust the above, it is possible to form the optimum classification region 30 depending on the raw material powder to be classified.

Above and below the block 33, inlet pipes 14 and 15 which are open to the classification chamber 32 are provided.
Further, these air intake pipes 14 and 15 are provided with a first gas introduction adjusting means 20 and a second gas introduction adjusting means 21 and static pressure gauges 28 and 29, such as dampers. A gas such as air is sent into the classification chamber 32.

Further, on the right side of the classification chamber 32, the coarse powder discharge port 11, the medium powder discharge port 12 and the fine powder discharge port 12 which are opened in the classification chamber 32 are provided corresponding to the respective curved classification regions 30. Exit 1
3, a communication means such as a pipe is connected to the discharge ports 11, 12 and 13, but each of them may be provided with an opening / closing means such as a valve means. In the airflow classifier of the present invention, as shown in FIG. 1, a coarse powder discharge port 11 for discharging the classified coarse powder group is a fine powder discharge port for discharging the classified fine powder group. It is preferable to be installed below the intermediate powder outlet 12 for discharging the intermediate powder group 13 and the intermediate powder group because accurate classification can be performed.

In the airflow type classifying device of the present invention, FIG.
Unlike the conventional classification device shown in FIG. 1, the raw material supply nozzle 16, the raw material powder introduction nozzle 42, and the high-pressure air supply nozzle 41 are arranged above the classification chamber 32 of the device as shown in FIG. The body particles are introduced into the classification chamber 32 from the vertical direction through the raw material supply nozzle 16 together with the air flow. At this time, in order to carry the raw material powder particles on the air stream, it is preferable to dispose the high-pressure air supply nozzle 41 for accelerating the raw material powder on the upstream side of the raw material supply nozzle 16. Furthermore, it is preferable to arrange both the raw material powder introduction nozzle 42 and the high-pressure air supply nozzle 41 on the upstream side of the raw material supply nozzle 16.

Further, in the gas stream type classifying apparatus of the present invention, all of the raw material supply nozzle 16, the raw material powder introduction nozzle 42 and the high pressure air supply nozzle 41 are θ = 4 with respect to the vertical direction.
It is preferable to install at an acute angle of 5 ° or less. Such a configuration is preferable because it is possible to prevent the particle flow from being roughly divided into an upper flow and a lower flow due to gravity as described above.

In the example shown in FIG. 1, the raw material supply port 40 for introducing the raw material powder into the air stream classifier is arranged at the most upstream part of the apparatus, and the raw material supply port 40 and the raw material supply nozzle 1 are provided.
6, a high pressure air supply nozzle 41 and a raw material powder introduction nozzle 42 are provided. And FIG. 1 and FIG.
As shown in FIG. 3, the high pressure air supply nozzle 41 provided at the upstream end of the raw material supply nozzle 16 is arranged in the center of the raw material powder introduction nozzle 42, and the outer wall of the high pressure air supply nozzle 41 and the raw material powder. A raw material introduction port 42 ′ for introducing the raw material powder is provided between the body introducing nozzle 16 and the inner wall of the body introducing nozzle 16.

Further, in the air flow type classifying apparatus of the present invention, it is preferable to provide a high pressure air swirl introduction passage 43 for swirling and injecting high pressure air into the upstream portion of the high pressure air supply nozzle 41. It is preferable that the high-pressure air swirl introduction path 43 is configured so as to be introduced from the tangential direction of the circle drawn when the high-pressure air supply nozzle 41 is horizontally cut as shown in FIG. With the above configuration, the high pressure air ejected from the nozzle 41 is introduced into the raw material supply nozzle 16 while forming a swirling flow.

As a result, the raw material powder supplied from the raw material supply port 40 is supplied from the raw material introduction port 42 'to the raw material supply nozzle 16
The high-pressure air, which has been swirled by the introduction of air from the introduction passage 43, is introduced into the raw material supply nozzle 16 from the high-pressure air supply nozzle 41 at this time. The powder is carried in the raw material supply nozzle 16 by a swirling flow having a strong dispersion force, and is introduced into the classification area 30.

The raw material supply nozzle 16 for carrying the powder raw material to the classification area as described above is provided on the right side of the side wall 22 and has an opening in the classification chamber 32. Then, the raw material powder is introduced together with the air flow from the opening into the classification area. As shown in FIG. 2, the raw material supply nozzle 16 is composed of a lower pyramid cylinder portion 35 having an opening provided in the classification chamber 32 and an upstream right-angled cylinder portion 36 following the pyramid cylinder portion 35. Is preferred. Then, if the ratio of the inner diameter of the right-angled tube portion 36 to the inner diameter of the narrowest part of the pyramidal tube portion 35 is set to 20: 1 to 1: 1, more preferably 10: 1 to 2: 1, a good raw material powder is obtained. The rate of introduction of the body is obtained.

Further, in the gas stream classifier of the present invention, as shown in FIGS. 1 and 2, the powder particles introduced from the vertical direction following the lower part of the raw material supply nozzle 16 as described above. The Coanda ribbon 26 is installed so as to draw a long ellipse. As mentioned above, the Coanda ribbon 26
Is configured like a kind of ribbon using an elastic material such as aluminum or copper having a thickness of several mm.
Therefore, it is easy to move the Coanda ribbon 26, and it is possible to arbitrarily change the Coanda diameter of the Coanda block. Therefore, for example, the intrinsic physical property value of the raw material powder such as toner, particularly density, average particle size,
Alternatively, the Coanda diameter can be changed according to the cohesiveness. Therefore, the Coanda diameter can be arbitrarily adjusted so that the optimum curved flow can be obtained for each raw material powder in the classification region 30.

The classification operation in the multi-division classification area (three divisions in this example) configured as described above is performed as follows, for example. That is, first, the inside of the classification chamber 32 is decompressed through at least one of the coarse powder discharge port 11, the medium powder discharge port 12, and the fine powder discharge port 13. Due to the depressurization, an airflow flows through the raw material supply nozzle 16 having an opening in the classification chamber 32 toward the classification chamber 32. As a result, the raw material powder is ejected into the classification chamber 32 through the raw material supply nozzle 16. At this time, the flow rate of the gas and the raw material powder in the raw material supply nozzle 16 is preferably 50 to 300 m / sec.

The particles in the powder introduced into the classifying chamber 32 have the function of the Coanda effect of the Coanda ribbon 26,
At this time, the raw material supply nozzle 16 and the inlet pipes 14 and 15 move in a curved line by the action of gas such as air flowing in. Then, depending on the particle size of each particle and the magnitude of the inertial force, a large particle (coarse powder) is transferred to the outside of the air flow, that is, to the first fraction below the classification edge 18, and a medium-sized particle. The (medium powder) is classified into the second fraction between the classification edges 18 and 17, and the small particles (fine powder) are classified into the third fraction above the classification edge 17, respectively. Is discharged from the discharge port 11, medium powder is discharged to the outside from the discharge port 12, and fine powder is discharged to the outside from the discharge port 13.

In the classification of the powder according to this example, the classification point is mainly determined by the position where the raw material powder jumps out into the classification chamber 32 and the tip positions of the classification edges 17 and 18 located on the lower right side of the Coanda ribbon 26. To be done. Further, the classification point is affected by the flow rate of the classification airflow, the ejection speed of the raw material powder from the raw material supply nozzle 16, and the like.

Generally, the airflow type classifying apparatus of the present invention is used by being incorporated in a classifying apparatus system in which mutual devices are connected by a communicating means such as a pipe. A preferred example of an integrated classifier system including the airflow classifier of the present invention is shown in FIG.
It was shown to. The classifying device system shown in FIG. 5 includes a three-division classifying device 1 (classifying device shown in FIGS. 1, 2, 3, and 4), a constant quantity feeder 2, a vibrating feeder 3, and a collecting device described above. The cyclones 4, 5 and 6 are connected by communication means.

In this classifier system, the raw material powder is fed to the constant quantity feeder 2 by an appropriate means, and then introduced into the three-division classifier 1 through the vibrating feeder 3 by the raw material supply nozzle 16. At this time, the raw material powder is introduced into the three-division classifier 1 so that the raw material powder and the gas flow through the raw material supply nozzle 16 at a flow rate of 50 to 300 m / sec. Generally, the size of the classifying chamber of the three-division classifying apparatus 1 is usually about [10 to 50 cm] × [10 to 50 cm], so that the raw material powder is classified into three kinds at an instant of 0.1 to 0.01 seconds. It can be classified into particle groups. Then, after being classified into large particles (coarse powder), medium-sized particles (medium powder) and small particles (fine powder) by the three-division classifier 1, the classified coarse powder is discharged. It is discharged to the outside of the system through the conduit 11a and collected by the collection cyclone 6. The medium powder is discharged to the outside of the system via the discharge conduit 12a and collected by the collection cyclone 5, and the fine powder is discharged to the outside of the system via the discharge conduit 13a and collected by the collection cyclone 4. These collection cyclones 4, 5 and 6 can also be made to function as suction pressure reducing means for feeding the raw material powder into the classification chamber 32 through the raw material supply nozzle 16.

The airflow type classifying apparatus of the present invention having the above-mentioned structure is particularly effective for classifying toner or colored resin powder for toner used in the image forming method by electrophotography. In recent years, toner particles have tended to be gradually miniaturized in order to improve image quality in copiers and printers. Getting bigger.

When such toner particles having a strong cohesive force are supplied to a conventional airflow classifier for classification, a sufficient dispersion force cannot be obtained in the raw material supply nozzle, and as a result, accurate classification is performed. In some cases, the product may not be obtained, and in the particle group after classification, which should otherwise be uniform in size, particles of a size that should be in another particle group may be mixed. It was That is, particles that should originally enter the fine powder group or the medium powder group are mixed in the coarse powder group due to insufficient dispersion of the raw material powder particles when being introduced into the classification chamber 32. There were cases.

That is, when minute toner particles having large cohesiveness are supplied to a conventional airflow classifying device for classification, particles having large density and large inertial force are obtained because the radius of the Coanda block is fixed. At the time of classification, the curved airflow is separated from the Coanda block, and a stable flow cannot be obtained. On the other hand, an inertial force such as low density or small-sized particles like toner is applied. When classifying difficult-to-treat powders, since the ejection distance of the powders is short, the classification area 30 becomes extremely narrow, and it is impossible to perform accurate classification.

On the other hand, in the airflow classifying apparatus and the toner manufacturing method of the present invention, since the high pressure air flowing in the raw material supply nozzle is a swirl flow, the airflow increases the shearing property for dispersing the toner particles, and the toner particles Dispersion power increases. For example,
By providing an introduction path 43 for swirling and injecting air into the upper part of the high-pressure air supply nozzle 41 to generate a swirling flow of high-pressure air, the raw material supply nozzle can be used even when the toner fine particles whose cohesive force has increased in recent years are used as the raw material powder. As a result of being able to obtain a sufficient dispersion force inside, it is possible to perform highly accurate classification in a constantly stable state.

Further, in the gas stream classifying apparatus and the toner manufacturing method of the present invention, by using the Coanda ribbon in the Coanda block, the Coanda diameter can be made to be a physical property value peculiar to the raw material powder, particularly the particle diameter of the raw material powder. Since it can be appropriately changed depending on the density and the cohesiveness of the powder, efficient classification can be achieved regardless of the type of the raw material powder. The Coanda ribbon 26 used in the present invention is composed of a kind of ribbon-like member made of an elastic material and having a thickness of several mm and a width of several cm to several tens of cm. As shown, it is arranged below the opening of the raw material supply nozzle 16. As the elastic material used at this time, any material having a certain degree of elasticity can be used so that the diameter of the elliptical arc can be arbitrarily changed, but the particles slide on the surface. It is preferable to use a material having excellent wear resistance and fusion resistance, which does not damage the Coanda ribbon even if it moves and does not cause surface fusion of particles. Examples of such a material include a thin plate of a metal such as aluminum or copper, or a thin film of these materials coated with a synthetic resin. Further, as the thickness of the Coanda ribbon 26 used in the present invention, specifically,
It is preferably 0.3 to 3 mm.

As described above, in the air stream classifier of the present invention,
Since the Coanda ribbon 26 is composed of a member having elasticity, and the Coanda diameter can be changed by moving the member, as shown in FIG. 4, the Coanda diameter is appropriately adjusted to an arbitrary size. It can be adjusted. For example, it is possible to realize the density of the physical properties peculiar to the raw material powder such as the toner, the average particle diameter, or the optimum Coanda diameter according to the powder cohesiveness. As a result, the optimum classification area 30 is formed according to the characteristics of the raw material powder.

For example, by moving the Coanda ribbon 26,
Coanda radius r (mm) and raw material powder density ρ (g / cm
It is preferable to set the Coanda diameter so that the following relationship is established with ³ ). When 1.3 <ρ, when 14 <r ρ ≦ 1.3, r <14 That is, when the density of the raw material powder is as large as 1.3 <ρ and the particle having a large inertial force is classified, the Coanda radius is Is less than 14 mm, the curved airflow is separated from the Coanda block 26, and a stable airflow along the block cannot be obtained, which is not preferable. On the other hand, when classifying particles that have a low density of the raw material powder of ρ ≦ 1.3 and are difficult to be given an inertial force, the ejection distance of such powder becomes short, and the Coanda radius is large at 14 mm or more. If so, the classification area 30 becomes extremely narrow, and accurate classification becomes impossible, which is not preferable.

Further, for example, in the case of classifying particles having a small average particle diameter of raw material particles to which inertial force is hard to be applied, it is preferable to set the Coanda diameter small as in the case of particles having a low density. When classifying particles having a large average particle diameter and a large inertial force, it is preferable to set a large Coanda diameter as in the case of particles having a high density.

[0036]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Example 1 100 parts by weight of styrene-butyl acrylate-divinylbenzene copolymer (monomer polymerization weight ratio 80.0 / 19.0 / 1.0, weight average molecular weight Mw 350,000) 100 parts by weight magnetic iron oxide (average particle size of 0. 18 μm) 100 parts by weight Nigrosine 2 parts by weight Low molecular weight ethylene-propylene copolymer 4 parts by weight After thoroughly mixing the above materials with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Kakoki Co., Ltd.), temperature 150 ° C
The kneading was carried out using a twin-screw kneader (PCM-30 type, manufactured by Ikegai Tekko KK) set to. The obtained kneaded material was cooled and coarsely pulverized with a hammer mill to 1 mm or less to obtain a coarsely crushed material for toner production. This coarsely pulverized product was finely pulverized by a collision type air flow pulverizer to obtain a weight average particle diameter of 6.7 μm and a density of 1.8 [g / c.
m ³ ], and a pulverized raw material having an aggregation degree of 52% was obtained.

Using the obtained pulverized raw material as raw material powder, using the classifying apparatus system shown in FIG. 5, first, 35.0 kg / h is passed through the constant quantity feeder 2, the vibration feeder 3 and the raw material feeding nozzle 16. The raw material powder was introduced into the three-division classifier 1 at a ratio of. As shown in FIGS. 1 to 4, the three-division classifier 1 classifies the raw material powder into three types of coarse powder, medium powder, and fine powder by utilizing the Coanda effect. At the time of introducing the raw material powder, the suction force generated in the system by the suction decompression of the collection cyclones 4, 5 and 6 communicating with the discharge ports 11, 12 and 13 and the inside of the raw material powder introduction nozzle 42 are introduced. The swirling compressed air from the attached high pressure air nozzle 41 was used. The Coanda ribbon has a thickness of 2 mm and a width of 1 c.
Although an aluminum plate of m was used, the Coanda radius was 20.
It was used after adjusting to mm.

The introduced raw material powder was classified in an instant of 0.1 second or less. The classified medium powder has a weight average particle size of 6.
9 μm (containing 22% by number of particles having a particle size of 4.00 μm or less and 1.0 volume% of particles having a particle size of 10.08 μm or more), and the classification yield at this time was 93%.
The obtained intermediate powder had excellent performance for toner. Here, the classification yield means the ratio of the finally obtained intermediate powder to the total amount of the raw material powder charged.

The particle size distribution of the toner used above can be measured by various methods. In the present invention, the particle size distribution was measured using the following measuring device. First, as a measuring device, Coulter Counter TA-II type or Coulter Multisizer II (both manufactured by Coulter Co.)
Was used. Further, as the electrolyte aqueous solution used for the measurement, an about 1% NaCl aqueous solution prepared using primary sodium chloride was used. As such a thing, for example, ISO
TONR-II (manufactured by Coulter Scientific Japan Co.) can be used. As a specific measuring method, first, 100 to 150 ml of the above-mentioned electrolyte aqueous solution
A surfactant, preferably 0.1 to 5 ml of alkylbenzene sulfonate is added as a dispersant, and 2 to 20 mg of a measurement sample is further added. Next, the electrolyte aqueous solution in which this sample was suspended was placed in an ultrasonic disperser to perform dispersion treatment for about 1 to 3 minutes. Then, using the above-described measuring device, the volume and number of toner were measured using a 100 μm aperture as an aperture to calculate the volume distribution and number distribution. Then, the weight-based weight average particle diameter obtained from the volume distribution was obtained.

Further, in the present embodiment, the toner density was measured as follows. Approximately 1 g of the toner is placed in a tablet molding machine for IR measurement, and is pressed at a pressure of approximately 196 × 10 ⁵ Pa for 1 minute to mold. The volume and weight of this sample are measured to determine the density.

In this example, the agglomeration degree of the raw material powder was measured as follows. Place the raw material powder on a 200 mesh sieve and weigh 5 g of the passed powder. 60me in powder tester (Hosokawa Micron Co., Ltd.) from top to bottom
Set the sieves in three layers in the order sh, 100mesh, 200mesh, and place 5 g of the sample weighed on the sieve gently,
Vibration with an amplitude of 1 mm was applied for 65 seconds, the weight of the raw material powder remaining on each sieve was measured, and the degree of aggregation was calculated according to the following formula. Note that W in the formula is the weight of the sample placed on the sieve. Aggregation degree = (weight of residual sample of 60 mesh) / W x 100 +
(Remaining sample weight of 100 mesh × 3/5) / W × 100 +
(Weight of remaining sample of 200 mesh x 1/5) / W x 100

Example 2 Example 1 was the same as Example 1 except that the coarsely pulverized product for toner production was used as the raw material powder and the tip positions of the classification edges 17 and 18 and the setting positions of the classification edge blocks 24 and 25 were changed. In the same manner as above, classification was performed using the classifier system in FIG. Table 1 shows the classification conditions in that case. As a result, as shown in Table 2, a medium powder having a sharp distribution could be efficiently obtained. Moreover, the classified product had excellent performance for toner.

Example 3 As a raw material powder, the coarsely pulverized product for toner production shown in Table 1 obtained by the same method as in Example 1 was used, and the classification apparatus system shown in FIG. 5 was used as in Example 1. I did the classification. The classification conditions are shown in Table 1. Table 1 shows the classification conditions in that case.
As a result, as shown in Table 2, a medium powder having a sharp distribution could be efficiently obtained. Moreover, the classified product had excellent performance for toner.

Example 4 The same as Example 3 except that the same raw material powder as that used in Example 3 was used and the tip positions of the classification edges 17 and 18 and the setting positions of the classification edge blocks 24 and 25 were changed. Then, classification was performed using the classifier system shown in FIG. The classification conditions are shown in Table 1. As a result, as shown in Table 2, a medium powder having a sharp distribution could be efficiently obtained. Further, this intermediate powder had excellent performance for toner.

Example 5 • Unsaturated polyester resin 100 parts by weight • Copper phthalocyanine pigment (CIPigment Blue 15) 4.5 parts by weight • Charge control agent 4.0 parts by weight The above materials were used as a Henschel mixer (FM-75 type, Mitsui Miike). After thoroughly mixing with Kakoki Co., Ltd., a twin-screw kneader (PCM-30 type, Ikegai Iron Works Co., Ltd.) set at a temperature of 100 ° C
Kneaded). The obtained kneaded material was cooled and coarsely pulverized with a hammer mill to 1 mm or less to obtain a coarsely crushed material for toner production. The coarsely pulverized product was finely pulverized by a collision type air flow pulverizer to obtain a raw material powder having a weight average particle diameter of 6.4 μm, a density of 1.1 [g / cm ³ ] and an aggregation degree of 65%.

The raw material powder obtained above is subjected to a multi-division classifying device at a rate of 26.0 kg / h through the quantitative feeder 2, the vibrating feeder 3 and the raw material feeding nozzle 16 of the classifying system shown in FIG. Introduced in 1. The multi-division classifier 1 used in this example is the three-division classifier shown in FIGS. 1 to 4 for classifying into three types of coarse powder, medium powder and fine powder by utilizing the Coanda effect. At the time of introduction, the suction force derived from the system by suction decompression of the collection cyclones 4, 5 and 6 communicating with the discharge ports 11, 12 and 13 and the high pressure air nozzle 41 attached to the raw material powder introduction nozzle 42 The swirling compressed air was used. The thickness of the Coanda ribbon is 2
An aluminum plate with a width of 1 cm and a width of 1 cm was used, but the Coanda radius was adjusted to 10 mm. The classified medium powder has a weight average particle size of 5.6 μm (38% by number of particles having a particle size of 4.00 μm or less and 0.1% by volume of particles having a particle size of 10.08 μm or more are contained). At this time, the classification yield of the medium powder having was 76%. The obtained intermediate powder is
It had excellent performance for toner.

Example 6 The same raw material powder as in Example 5 was used as the raw material powder, and classification edge 1 was used.
Classification was performed under the same conditions and in the same apparatus system as in Examples 5 and 3, except that the tip positions of 7 and 18 and the setting positions of the classification edge blocks 24 and 25 were changed. As a result, the classified intermediate powder had a weight average particle diameter of 5.9 μm (particle diameter of 4.00).
Contains 35% by number of particles of μm or less, and has a particle size of 10.08μ.
0.1% by volume of particles of m or more is contained. ), And the classification yield at this time was 74%. The obtained intermediate powder is
It had excellent performance for toner.

Table 1 Classification conditions in Examples

Table 2 Particle size distribution and classification yield of the intermediate powders obtained in the examples

Comparative Example 1 The same coarsely crushed material as in Examples 1 and 2 was used as a raw material powder, and the raw material powder was used in the classification apparatus system shown in FIG.
Quantitative feeder 2, vibrating feeder 3 and raw material feeding nozzle 1
The raw material powder was introduced into the multi-division classifier 101 at a rate of 31.0 kg / h through 16. The multi-division classifier 101 uses the Coanda effect to classify into three types of coarse powder, medium powder and fine powder, as shown in FIG.
01 was used. At the time of introduction, the suction force derived from the system due to the suction pressure reduction of the collection cyclones 4, 5 and 6 communicating with the discharge ports 11, 12 and 13 and the compression from the injection nozzle 31 attached to the raw material acceleration nozzle 34. I used air. The air flow in the raw material supply nozzle 116 is
The flow was not a swirl flow, but a flow proceeding horizontally to the pipe wall of the raw material supply nozzle 116. In the three-division classifier 101, the Coanda radius of the Coanda block 126 is 14 mm.
It is fixed at. As a result of the above, the classified intermediate powder has a weight average particle size of 6.8 μm (containing 25% by number of particles having a particle size of 4.00 μm or less and 3% by volume of particles having a particle size of 10.08 μm or more). And had a broader distribution than in Examples 1 and 2. In addition, the classification yield at this time was 70%, and
The yield was inferior compared to.

Comparative Example 2 The same crushed material as in Example 3 and Example 4 was used as the raw material powder,
In the same manner as in Comparative Example 1 except that the amount of the raw material powder introduced was set to 26.0 kg / h, the raw material powder was introduced into the conventional three-division classifier 101 shown in FIG. Classified into 3 types of body. As a result, the classified intermediate powder has a weight average particle size of 5.6 μm (40% by number of particles having a particle size of 4.00 μm or less, and 3% by volume of particles having a particle size of 10.08 μm or more).
Content), and had a broader distribution than in Examples 3 and 4. Further, the classification yield at this time was 68%, which was inferior to the yields of Example 3 and Example 4.

Comparative Example 3 The same crushed material as in Example 5 and Example 6 was used as the raw material powder,
In the same manner as in Comparative Example 1 except that the amount of the raw material powder introduced was set to 26.0 kg / h, the raw material powder was introduced into the conventional three-division classifier 101 shown in FIG. Classified into 3 types of body. The classified medium powder has a weight average particle diameter of 5.8.
μm (contains 40% by number of particles having a particle size of 4.00 μm or less and 3% by volume of particles having a particle size of 10.08 μm or more), and has a broader distribution than those of Example 5 and Example 6. I had one. Further, the classification yield at this time was 67%, which was inferior to the yields of Example 5 and Example 6.

Table 3 Classification conditions of comparative example

Table 4 Particle size distribution and classification yield of the obtained intermediate powder

[0055]

As described above, according to the airflow type classification apparatus and the toner manufacturing method of the present invention, even toner particles having an increased cohesive force in recent years can be sufficiently dispersed in the raw material supply nozzle. Therefore, highly accurate classification is possible in a stable state at all times. Further, according to the airflow classifying apparatus and the toner manufacturing method of the present invention, it becomes possible to appropriately change the Coanda diameter by using the Coanda ribbon in the Coanda block, and as a result, various toner particle densities and particles can be obtained. Accurate classification points can be obtained depending on the inherent physical properties such as diameter and the difference in air flow conditions, and highly accurate classification is possible in a stable state at all times. The airflow classifying apparatus and toner manufacturing method of the present invention are particularly effective when classifying toner fine particles having a weight average particle diameter of 10 μm or less.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an airflow type classification device of the present invention.

FIG. 2 is an exploded view showing a classification section of the airflow classification apparatus of the present invention three-dimensionally.

FIG. 3 is a sectional view taken along line A-A 'in FIG.

FIG. 4 is an enlarged view of a classification chamber of the airflow type classification device of the present invention.

FIG. 5 is an explanatory view showing an example of a classification process using the airflow classification device of the present invention.

FIG. 6 is a schematic sectional view of a conventional airflow classifier.

FIG. 7 is an explanatory diagram showing an example of a conventional classification process.

[Explanation of symbols]

 1, 101: Airflow type classifier 2: Fixed amount feeder 3: Vibration feeder 4, 5, 6: Collection cyclone 11, 12, 13: Discharge port 11a, 12a, 13a: Discharge conduit 14, 15: Intake pipe 16, 116: Raw material supply nozzle 17, 18, 117, 118: Classification edge 17a, 18a: Classification edge axis 19: Intake edge 20: First gas introduction adjusting means 21: Second gas introduction adjusting means 22, 23: Side wall 24, 25, 124, 125: Classification edge block 26: Coanda ribbon 27: Upper block 28, 29: Static pressure gauge 30: Classification area 31: Injection nozzle 32: Classification chamber 33: Block 34: Raw material accelerating nozzle 40: Raw material supply port 41 : High-pressure air supply nozzle 42: Raw material powder introduction nozzle 43: High-pressure air swirl introduction path 126: Coanda block

Claims (10)

[Claims] 1. A raw material powder supplied from a raw material supply nozzle is at least a coarse powder group, a medium powder group and a fine powder group by a Coanda effect in a classification area formed by at least a Coanda block and a plurality of classification edges. Air flow type classifying device for classifying, a raw material supply nozzle, a raw material powder introduction nozzle and a high pressure air supply nozzle are arranged above the classifying chamber of the device, and the shape of the classification area in the classification chamber can be changed. In such an air flow type classifying device in which the classifying edge is rotatable and the position of the classifying edge block provided with the classifying edge is movable, high pressure air ejected from the high pressure air supply nozzle Is configured to swirl and flow, and the Coanda diameter of the Coanda block can be changed according to the intrinsic physical property value of the raw material powder. Airflow type classifier. 2. The raw material supply nozzle, the raw material powder introduction nozzle, and the high-pressure air supply nozzle are θ = 45 with respect to the vertical direction.
The airflow classifier according to claim 1, wherein the airflow classifier is installed at an angle of less than or equal to °. 3. A coarse powder discharge port for discharging the classified coarse powder group, a fine powder discharge port for discharging the classified fine powder group, and a discharged medium powder group for classification. The airflow classifier according to claim 1 or 2, which is installed below the medium powder discharge port. 4. The airflow classifier according to claim 1, wherein a high-pressure air supply nozzle for accelerating the raw material powder is installed at the upstream end of the raw material supply nozzle. 5. The air flow according to claim 1, wherein a raw material powder introduction nozzle and a high-pressure air supply nozzle for accelerating the raw material powder are installed at an upstream end of the raw material supply nozzle. Type classifier. 6. A high pressure air supply nozzle provided at an upstream end of the raw material supply nozzle is arranged at the center of the raw material powder introduction nozzle, and an outer wall of the high pressure air supply nozzle and an inner wall of the raw material powder introduction nozzle. An air flow type classification apparatus according to any one of claims 1 to 5, wherein a raw material introduction port for introducing the raw material powder is provided between and. 7. An introduction path for swirling and injecting high-pressure air is provided in an upstream portion of the high-pressure air supply nozzle.
The airflow classifier according to any one of 1 to 6. 8. The Coanda block is formed of a movable member made of a material having elasticity called a Coanda ribbon, and by moving the Coanda ribbon, the density, particle size, or powder cohesiveness of the intrinsic physical properties of the raw material powder. The Coanda diameter of the Coanda block is changed according to
The airflow classifier according to any one of claims 1 to 7. 9. A Coanda radius r (m of the Coanda block
The airflow classification device according to claim 8, wherein m) is set so as to satisfy the following relationship with the density ρ (g / cm ³ ) of the raw material powder. When 1.3 <ρ, 14 <r When ρ ≦ 1.3, r <14 10. A toner manufacturing method having a classifying step of classifying a toner or a colored resin powder for a toner containing a binder resin used for image formation by electrophotography,
A toner manufacturing method, wherein the airflow classifying device according to claim 1 is used.