JPH07295294A - Manufacturing system for fine powder toner for electrostatic charge development - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a system for producing fine powder toner for electrostatic development, which solves the problems that are difficult in the conventional system for producing fine powder toner, unstable in efficiency, and impairing economy. It is what [Structure] First step of pulverizing raw material flakes with a mechanical pulverizer A, second step of classification, third step of re-pulverization with an air flow type pulverizer or mechanical pulverizer, separation of collected powder and air flow The fourth step, the fifth step of collecting the particles in the air stream, the sixth step of classifying the dust collecting powder obtained in the fourth step and the fifth step with a multi-product simultaneous classifier, the classified This system combines the seventh step of returning the collected coarse powder to the third step and the eighth step of collecting the particles in the air stream of the seventh step to take out the intermediate product as fine powder toner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for producing fine powder toner for electrostatic charge development used in copying machines and the like.

[0002]

2. Description of the Related Art Particle size is one of the conditions required for an electrostatic charge developing toner (hereinafter referred to as toner) in order to obtain a good image quality in a copying machine. At the same time, a narrow particle size distribution is required. On the other hand, in order to know the particle size distribution of the toner, an electric detection zone type particle size distribution measuring instrument such as a Coulter counter manufactured by Coulter Electronics Inc. in the United States is generally used. Therefore, in order to express the particle size of the toner, first, as a representative particle size, the particle size of 50% volume passing is defined as the average particle size μm (hereinafter,
It is referred to as d ₅₀ ) and is a representative value indicating the toner particle size. Most of the toners currently manufactured and used are d _50.
It is 12 μm or 10 μm, but for the purpose of improving the image quality of copying, it has a gradually smaller d ₅₀ of about 8 μm (hereinafter, a toner having a d ₅₀ of less than 10 μm is referred to as a fine powder toner).
Has begun to be used, and it is expected that it will shift to 7 μm to 5 μm in the future. Next, in order to show the range of the particle size distribution of the toner, the volume content% of particles larger than a certain particle size (hereinafter, referred to as upper cut value) and the volume content% of particles smaller than a certain particle size (( (Hereinafter, referred to as the lower cut value) is usually used. Table 1 shows an example of the upper cut value and the lower cut value for each d ₅₀ .

[0003]

[Table 1]

As can be seen from this table, as the d ₅₀ becomes smaller, the particle size range becomes narrower, and the conventional toner manufacturing system cannot cope with the current situation. On the other hand, there has been a demand for increasing the copying speed in a copying machine, and the toner has been improved along with the improvement of the copying machine itself. As the toner, high-speed copying is possible if the melting point is low, so that a synthetic resin such as a styrene acrylic acid copolymer having a low molecular weight and a low melting point is used as a toner material. The difference in molecular weight appears as a difference in resistance to crushing, and a high molecular weight synthetic resin is generally hard and difficult to crush, but a low molecular weight one is conversely soft and crushable easily. It is generally said that the best copy image quality is obtained when a somewhat hard toner is used in a low-speed copying machine. However, it is desirable to select a toner that also considers the copying speed. It usually has a hardness range of. In this way, it is important to manufacture an appropriate toner for each type of copying machine, which is now on the market, and pulverization of toner and colorization are progressing with the diversification of toner.

This toner is made by heating and melting and kneading the raw materials to make it homogeneous, and after cooling, it is 3 mm with a cutter mill or the like.
It is crushed to below a certain level to form so-called flakes. The flakes are crushed by a crusher up to a toner d _50, and a classifier removes coarse powder and fine powder other than the upper cut value and the lower cut value to obtain a target toner product. Was there. Then, the coarse powder was returned to the crusher again and repeatedly crushed. For the above-mentioned pulverization, an air flow type pulverizer so-called jet mill, for example, a supersonic jet mill manufactured by Nippon Pneumatic Co., Ltd. was mainly used. For classification, a swivel classifier, for example, a dispersion separator manufactured by Nippon Pneumatic Mfg. Co., Ltd. is preferably used. FIG. 6 shows a toner manufacturing system using such a conventional crusher and classifier.

[0006]

In the conventional toner manufacturing system shown in FIG. 6, raw material flakes are sequentially fed into an air flow type crusher by a feeder and crushed into fine powder I and coarse powder I by a preliminary classifier. Classify. The coarse powder I classified by the preliminary classifier is returned to the air flow type crusher and crushed again. On the other hand, the classified subdivided I is collected by the collection device I and the air stream is exhausted, and the collected powder is sent to the classifier that matches the upper cut value and exhausted, the fine powder II and the coarse powder product II. Classified as and. Of these, the coarse powder product II is larger than the upper cut value and is returned to the air flow type crusher and crushed. The fine powder II is collected by the collecting device II and divided into an air flow component and a collecting component, and the collected powder is exhausted, fine powder III, and coarse powder product III by a second classifier that fits the lower cut value. Be classified into. This coarse powder product III becomes a toner product as a conforming product that is smaller than the upper cut value and larger than the lower cut value.

As shown in FIG. 7, a supersonic jet mill is generally used as the air flow type pulverizer used in the above-described conventional toner manufacturing apparatus system. The supersonic jet mill 50 has a main body tube portion formed of a thin tube portion 51 and a thick tube portion 52, a hopper 54 for feeding a raw material 53 is provided on the thin tube portion 51, and a thick tube portion 52 has an inside. The columnar collision member 55 is provided, and the hopper 54 and the thin tube portion 51 are provided.
A jet nozzle 56 for sucking the raw material 53 by the expansion force of the compressed air and accelerating the particles at a connection position with
Are formed. It should be noted that the thin tube portion 51 and the thick tube portion 52 are
A jet port 57 for compressed air is provided at a position opposite to the connection side with the powder port 58, and a powder outlet port 58 is provided on the side opposite to the jet port 57 and on the thick pipe portion 52 side. In such a supersonic jet mill 50, when the raw material 53 is put into the hopper 54 that blows compressed air into the jet outlet 57, the jet nozzle 56
The raw material 53 is sent from the thin pipe portion 51 to the thick pipe portion 52 by the expansion force of the compressed air in the above, and collides with the colliding member 55 in the thick pipe portion 52 to be crushed. The crushed particles are squeezed out of the powder outlet 58 by the jet stream.

Further, the classifier used in the conventional toner manufacturing system is a swivel type as shown in FIG. 8 and is called a dispersion separator. This dispersion separator 60 has a cylindrical main body portion 61 with a narrowed bottom portion, a secondary air intake hole 62 is provided in the middle, and the rear side thereof has a vertical upper and lower portion in the center portion of the cylindrical body. Two conical classifying tables 63 and 64 are provided. A discharge pipe 65 is provided at the center of the lower sides of the classifying tables 63 and 64, and the other end is led out to one side of the main body 61 and provided with a fine powder outlet 67. On the other hand, a raw material inlet 68 for supplying the primary air and the raw material is provided on the upper portion of the main body 61, and a primary exhaust hole 69 is provided on the upper surface of the main body 61. On the rear surface side of the classifying table 63 of the classifying table, a concave portion having an inclined surface parallel to the inclined surface of the lower classifying table 64 is formed, and is configured to guide the fine powder by the secondary air. .

This dispersion separator 60
When the crushed raw material and the primary air are fed from the raw material inlet 68, the crushed particles fall while swirling along the inner circumference of the main body 61 and along the upper inclined surface of the classification table 63. Then, it falls on the classification table 64 below the end surface of the classification table 63. At this time, the fine powder is blown up by the secondary air and pushed up above the classifying table 64, enters the discharge pipe 65, is taken out from the fine powder take-out port 67, and is collected.
Then, the separation point between the coarse powder and the fine powder is adjusted by the air volume of the secondary air.

[0010]

However, in the conventional toner manufacturing apparatus having the above-mentioned structure, the grinding energy of the ultrasonic jet mill has to be increased in the present day when the fine powder toner is required for the copying machine, and the raw material flakes are required. To pulverize the powder to a predetermined particle size of, for example, 7 μm to 5 μm, too much compressed air power is required,
There is a problem in terms of economy. In addition, part of the fine particles of the classification material finely pulverized with a flat-angle jet mill are lost by the large amount of primary exhaust (hereinafter simply referred to as exhaust) extracted from the upper part of the classifier, resulting in a toner product. However, there was a fatal drawback that the yield of the product was very low and the economic efficiency was lost.

Further, in the dispersion separator,
Since the internal volume of the classifier is large and the powder is placed on the swirling flow for classification, the residence time of the particles in the machine is long, and while the fine particles are swirling inside the machine, the particles agglomerate with each other, The phenomenon of adhesion to the inner wall was observed. The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the problems of the conventional method in the production of fine powder toner, to obtain a fine powder toner product of a predetermined particle size from a raw material flake with good yield and economically. It is intended to provide a manufacturing system for obtaining

[0012]

In order to achieve the above object, a system for producing a fine powder toner for electrostatic charge development of the present invention has the following constitution. (1) In a system for producing a fine powder toner for electrostatic charge development from raw material flakes by pulverizing and classifying, a first step of pulverizing the raw material flakes by a mechanical pulverizer A, and a preliminary classification of the pulverized product obtained from this first step Second step of classifying into coarse powder and fine powder by a machine, a third step of crushing the coarse powder with an air flow type crusher B, a crushed product obtained in the third step, and a fine powder of the second step. After joining, the fourth step of separating the collected powder and the air flow by collection, and the fifth step of completely collecting from the air a very small amount of particles contained in the air flow of the fourth step And a sixth step in which the collected powder obtained in the fourth step and the dust collected in the fifth step are sent to a multi-product simultaneous classifier to classify into three products of coarse powder, medium powder and fine powder, and The 7th step of collecting each of these 3 products, separating each of the collected powders and the air flow, and sending back the collected coarse powders to the 3rd step And the eighth step of collecting extremely small amount of particles contained in the airflow generated in the seventh step and completely removing them from the air, by combining the intermediate powder product with a fine powder toner. A system for producing fine powder toner for electrostatic charge development, characterized by: (2) The system for producing fine powder toner for electrostatic charge development according to item (1), wherein the pulverizer for pulverizing the coarse powder in the third step is a mechanical pulverizer A.

[0013]

In the system for producing a fine powder toner for electrostatic charge development according to the present invention having the above-mentioned constitution, since the mechanical pulverizer is used in the first step, the economical efficiency is improved, and the coarse powder and the fine powder are classified in the second step. Then, the coarse powder is further pulverized by an air flow type or mechanical pulverizer, and the fourth step and the fifth step of adding the dust collecting powder to the supplementary powder are loaded to the sixth step. 3 products of coarse, medium and fine powder are classified by a product simultaneous classifier, and these 3 products are respectively collected, but the collected intermediate powder is stored as fine powder toner, and the coarse powder is collected. In addition to feeding back to the third step, the eighth step was added to add the fine powder collected and the airflow of each collecting device to the dust collecting powder separated from the clean air by the dust collecting device. Whether it is low or high, we can handle it, Is a system that can be economically producing fine toner from.

A system for producing a fine powder toner for electrostatic charge development of the present invention (hereinafter referred to as "a system for producing a fine powder toner") will be described below with reference to FIGS. 1 and 2 show all steps of a fine powder toner manufacturing system characterized by combining the first step to the eighth step necessary for pulverizing and classifying raw material flakes to obtain a toner product. Of these, the system shown in FIG. 1 is suitable when the hardness of the raw material flakes is high, and the pulverization is performed in two stages.
Each is composed of a mechanical crusher A and an airflow crusher B. On the other hand, the system of FIG. 2, on the contrary, is suitable for production from raw material flakes having a low hardness, and is characterized in that the mechanical pulverizer A is used for both pulverization steps.

Each step constituting the fine powder toner manufacturing system of the present invention will be briefly described. In the first step, the raw material flakes are crushed by the mechanical crusher A. In the second step, a preliminary classifier is used to classify into coarse powder and fine powder. In the third step, if the flake hardness is high, the air flow type crusher B is used.
On the contrary, when the hardness is low, it is pulverized by the mechanical pulverizer to the final particle size required for the classification raw material, and merged with the fine powder in the second step. The fourth step is a separation step of air and powder using a cyclone, which can be divided into collected powder and air flow, but the trace amount of powder that escapes with the air flow is collected by the dust collection in the fifth step. It is removed as dust, separated from clean air, and sent to the sixth step together with the collected powder of the fourth step. The sixth step is
It is a process of simultaneous upper and lower cutting by the multi-product simultaneous classifier C, and the obtained coarse powder, medium powder, and fine powder are

In the seventh step, each cyclone is collected to obtain each product. The collected coarse powder product obtained by the coarse powder collection is repeatedly processed in the third step. The target powder product is the fine powder toner product. The very small amount of powder that escapes with the air flow without being collected by each cyclone in the seventh step is removed by the dust collection in the eighth step and separated from the clean air. In addition, in the sixth step and the eighth step,
Each is equipped with a blower. A cyclone having a diameter suitable for the amount of air is usually used for collection, but a dust collector is a filter, and a Sinter Lamellar Filter manufactured by Nittetsu Mining Co., Ltd. is most suitable. Here, an explanation will be given of the experimental results that lead to the conclusion that it is necessary to change the model of the crusher depending on the hardness difference of the toner raw material flakes. As shown in Table 2, the two types of raw material flakes prepared for the crushing test have the same material blending ratio, except that the molecular weights of the styrene-acrylic acid copolymer used as the synthetic resin differ greatly. Is.

[0017]

[Table 2]

Table 3 shows the results of a crushing test performed on these two types of raw material flakes having different hardnesses by the mechanical crusher A and the airflow crusher B.

[0019]

[Table 3]

As shown in Table 3, in the case of flakes 2 having a low hardness and easy to grind, the mechanical grinder A has two stages of 6 μm.
Therefore, it is not always necessary to use an air flow type pulverizer in the second stage, and therefore the two-stage system of the mechanical pulverizer A in FIG. 2 is suitable. In the mechanical crusher A, part of the power applied to rotate the crushing surface is converted into heat, so if the temperature inside the machine rises too much, the toner will melt and adhere to the crushing surface. Therefore, it is necessary to cool the machine and the crushed product using cold air that has been dehumidified, but even if the power is added, the installation power is far greater than the compressor power for the air flow type crusher B. In addition to being small, the amount of treatment is large, so the power consumption per unit weight of the pulverized product can be very small, which is an advantage of high economic efficiency.

On the other hand, flakes 3 having high hardness and difficult to be crushed
Even if the mechanical pulverizer A is passed through two stages, the reached particle size is 10
It is not possible to cut to less than 10 μm for the first time when the first-stage crushed product of mechanical crusher A is applied to airflow crusher B.
I was able to cut. However, it was found that the performance of the air flow type crusher B differs greatly depending on the model, and it is important to select the model from this, and the crusher A, that is, Eye. E. Only the C-made fluidized bed counter-jet mill was able to cut the target 6 μm. Next, Table 4 shows the results obtained by classifying the two types of crushed products thus crushed by an Elbow Jet classifier manufactured by Nittetsu Mining Co., Ltd. as a multi-product simultaneous classifier. Unlike conventional dispersion separators, elbow jet classifiers do not require exhausting the exhaust air from the top of the classifier, so there is no loss of some of the fine particles in the classifying material.
Further, the internal volume of the classifier is small, and the powder blown at high speed is instantaneously separated, so that there is an advantage that aggregation and adhesion do not occur.

[0022]

[Table 4]

FIG. 1 of the present invention obtained by combining the above steps with the flakes 3 having high hardness and difficult to be crushed.
The example using the system of FIG. 6 and the case of using the conventional system shown in FIG. 6 are taken as a comparative example. Shown in the table. Table 6 shows the yield and particle size of the resulting fine powder toner products.

[0024]

[Table 5]

[0025]

[Table 6]

The mechanical crusher A, the air flow crusher B, and the multi-product simultaneous classifier C used in the above-mentioned fine powder toner manufacturing system will be described below. As shown in FIG. 3, the mechanical crusher A is provided with a rotary shaft 1 at the center, and the rotary shaft 1 and a plurality of rotors 2 are rotatably attached. Distributors 3 are provided on one side of the rotors 2, blades 4 are provided at the tips of the rotors, and a partition disk 5 is sandwiched between the blades 4. A cylindrical casing 6 is provided on the outer periphery of the blade with a slight gap, and a liner 7 is arranged on the surface of the casing 6 corresponding to the blade, and the gap between the liner 7 and the blade 4 is crushed. A chamber 8 is formed. An inlet spiral chamber 9 is provided on the end surface of the casing 6 on the side where the distributor 3 is mounted, and an outlet spiral chamber 10 is provided on the opposite end surface. The rotating shaft 1 is provided outside the outlet spiral chamber 10 of the casing 6.
Is extended, and a pulley 11 to which the rotational force from the drive source is transmitted is provided on the end surface of the rotating shaft.

In the mechanical crusher A having the above-described structure, the raw material flakes are put into the inlet spiral chamber 9 and the pulley 11 is rotated to rotate the blades 4 via the rotary shaft 1 and the distributor 3. The raw material flakes are sent into the crushing chamber 8 and crushed. Then, the crushed product which has passed through the crushing chamber 8 and is discharged to the outlet swirl chamber 10 together with the air flow introduced together with the raw material flakes by an unillustrated exhauster connected to the downstream of the crusher is collected in the upper part of the figure. It As shown in FIG. 4, the air flow type crusher B is provided with a box 12 which is closed by a cylindrical vertical type, a plurality of crushing jet nozzles 13 provided in the lower part of the box 12, and is connected to this. A compressed air header 14, a raw material supply port 15 provided in the middle of one side of the box 12, a level detection device 16 attached to the opposite side, and a crushed product fed into the box 12. It is a fluidized bed type counter jet mill formed by a take-out port 17 and a classifier rotor 18 which is disposed so as to face the crushed product take-out port 17 and classifies the crushed product while rotating.

In this air flow type pulverizer B, the raw material particles supplied to the box 12 and forming the fluidized bed collide with each other by the high pressure air streams ejected from the pulverizing jet nozzle 13 to be pulverized, and the classifier rotor 18 is provided. Only the fine powder classified through the crushed product is taken out from the crushed product outlet 17. Further, the classified coarse powder is returned to the box body and pulverized. The raw material fluidized bed inside the box 12 is kept constant by the operation of the level detection device 16.

As the multi-product simultaneous classifier C, an elbow jet classifier shown in FIG. 5 is used. This multi-product simultaneous classifier C is connected to an ejector (not shown), which forms a dispersed air flow of powder by utilizing the expansive force of compressed air, inside the rectangular casing 19 and contacts the lower part of the raw material nozzle 25 so as to contact the conductor. The block 26 is arranged, and the G block 22 is provided facing it. The raw material particles blown from the raw material supply nozzle 25 have a horizontal inertial force according to the particle volume and velocity, but are introduced from the air inlets 20 and 21 by being made negative pressure by an unillustrated exhaust fan. The coarse particles flow closer to the G block and, conversely, the fine particles flow closer to the Coanda block due to the resultant force of the resistance force of the air flow having the vertical velocity. Therefore, the housing 19
By disposing the first classifying edge 28 and the second classifying edge 29 arranged below the No. 3, the fine powder having different particle diameters from the fine powder passage 27, the intermediate powder from the intermediate powder passage 30 and the coarse powder are coarsely divided. Each of the classified products can be obtained by separating from the powder passage 23 by a collecting device (not shown). Also, the first and second
The particle size of the product can be adjusted by adjusting the tip positions of the respective classification edges.

Mechanical crusher A and air flow crusher B described above
As mentioned above, the mechanical crusher A is used in the first step and the air flow crusher B is used in the third step depending on the hardness of the raw material flakes.
Or a mechanical pulverizer A is provided in both the first step and the third step, so that a fine toner powder production system can be obtained efficiently and economically. Table 7 shows the machine names used in this example and the conventional example used for the test for producing the fine powder toner from the raw material flakes. .

[0031]

[Table 7]

[0032]

As described in detail above, in the system for producing electrostatically developing fine powder toner of the present invention, the fine powder toner (d ₅₀ (Less than 10 μm), it is possible to provide a fine toner with a fine particle size and a narrow particle size range in a high yield, and to reduce the power consumption, thereby providing an economically low cost system. is there.

[Brief description of drawings]

FIG. 1 is a flowchart of a fine powder toner manufacturing system showing a first embodiment of the present invention.

FIG. 2 is a flow chart of a fine powder toner manufacturing system showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a mechanical crusher used in the examples of FIGS. 1 and 2.

FIG. 4 is a sectional view of an airflow type crusher used in the embodiment of FIG.

5 is a cross-sectional view of a multi-product simultaneous classifier used in the examples of FIGS. 1 and 2. FIG.

FIG. 6 is a flow chart of a toner manufacturing system in a conventional example.

FIG. 7 is a sectional view of an airflow type crusher used in the embodiment of FIG.

8 is a sectional view of a classifier used in the embodiment of FIG.

[Explanation of symbols]

 A Mechanical crusher B Airflow crusher C Multi-product simultaneous classifier

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[Procedure amendment]

[Submission date] June 13, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

In the conventional toner manufacturing system shown in FIG. 6, raw material flakes are sequentially fed into an air flow type crusher by a feeder and crushed into fine powder I and coarse powder I by a preliminary classifier. Classify. The coarse powder I classified by the preliminary classifier is returned to the air flow type crusher and crushed again. On the other hand, the classified subdivision I is collected by the collection device I and the air stream is exhausted, and the collected powder is sent to the first classifier that matches the upper cut value, and exhausted, fine powder II, and coarse powder product. Classified as II. Of these, the coarse powder product II is larger than the upper cut value and is returned to the air flow type crusher and crushed.
The fine powder II is collected by the collecting device II and is divided into an air stream component and a collected component, and the collected powder is exhausted, fine powder III, and coarse powder product III by a second classifier that fits the lower cut value. Be classified into.
This coarse powder product III becomes a toner product as a conforming product that is smaller than the upper cut value and larger than the lower cut value.

Claims (2)

[Claims] 1. A system for producing a fine powder toner for electrostatic charge development from raw material flakes by pulverizing and classifying, the first step of pulverizing the raw material flakes with a mechanical pulverizer A,
Obtained by the second step of classifying the crushed product obtained from the first step into coarse powder and fine powder by a preliminary classifier, the third step of crushing the coarse powder by the airflow crusher B, and the third step. After combining the pulverized product and the fine powder of the second step, the fourth step of separating the collected powder and the air flow by collection, and the trace amount of particles contained in the air flow of the fourth step are collected. The fifth step of dusting and completely removing from the air, the collected powder obtained in the fourth step and the dust collecting powder obtained in the fifth step are sent to a multi-product simultaneous classifier, coarse powder, medium powder, A sixth step of classifying the fine powder into three products, a seventh step of collecting each of the three products and separating the collected powder and an air stream, and returning the collected coarse powder to the third step, The eighth step, which collects minute amounts of particles contained in the airflow generated in the seventh step and completely removes them from the air, is combined with each other to form a fine powder of the intermediate product. Fine toner manufacturing system for electrostatic charge development, characterized in that the over. 2. The system for producing a fine powder toner for electrostatic charge development according to claim 1, wherein the pulverizer for pulverizing the coarse powder in the third step is a mechanical pulverizer A.