JPH01205172A - Production of toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To efficiently and rapidly obtain particle groups having a fine grain size distribution in a prescribed grain size region by simultaneously removing coarse particle groups and fine particle groups by a specific classifying means as a 2nd classifying means. CONSTITUTION:A 1st classified fine particle obtd. by classification is captured through a conduit 102 into a capturing cyclone 5. This powder is taken out of the cyclone by an injection feeder 103 and is introduced through a conduit 104 and a capturing cyclone 105 into the 2nd classifying means 2, by which the powder is classified. The 2nd classified coarse powder classified in such a manner is captured in a capturing cyclone 6 and is ground by a 2nd grinder 4. The 2nd ground powder is introduced together with the 1st classified fine powder through a conduit 114 and a capturing cyclone 105 into the 2nd classifying means 2. On the other hand, the 2nd classified middle powder is captured by a capturing cyclone 8 and is discharged from a finished powder discharge port 81. The toner for electrostatic development having the uniform and fine grain size distribution is thereby efficiently obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently producing an electrostatic image developing toner having a sharp particle size distribution.

[Conventional technology]

Conventionally, as a method of finely pulverizing toner, a combination of one classifier and one pulverizer, or a combination of two classifiers and one pulverizer is known. Using a so-called jet mill, raw material particles are ejected from a nozzle, the jet stream entrains them, and the particles collide with each other or with a wall or other colliding body to proceed with pulverization.
One pulverizing means and one or two classifying means are combined for pulverization. FIGS. 2 and 3 are examples of conventional methods, respectively. In FIG. 2, the raw material is supplied through a raw material supply pipe 1, and the raw material together with the pulverized material is introduced into a classification means and separated into coarse powder and fine powder. The coarse powder is pulverized through the pulverizing means and introduced into the classifying means again. On the other hand, fine powder is discharged outside the system as a product.

However, in this system, the powder supplied to the classification means is not only the raw material powder but also toner particles of various particle sizes that are in the process of being pulverized, which are circulated between the pulverization means and the classification means. The particle size is very broad, and it is operated under a very heavy load. Therefore, the classified fine powder, that is, the pulverized product, contains many coarse particles that have an adverse effect on quality.

On the other hand, the coarse powder that is returned to the grinding process is mixed with many fine particles that do not need to be crushed any further, and as these fine particles are further crushed, the proportion of fine particles in the crushed product increases. Therefore, aggregates of fine powder may be generated, and even if the desired particle size is obtained by removing fine powder in the next classification step, the yield is low. In addition, as mentioned earlier, since the proportion of coarse powder and fine powder increases, images obtained using the developer made in this way have low density and have white spots with a lot of fog. It has its drawbacks. In addition, due to the poor performance of the classifier,
The problem is that the energy efficiency of crushing is poor.

As a means for improving the above, as shown in FIG. 3, a second classification means is provided, the first classification means removes fine powder at a relatively coarse classification point, and the third classification means further removes fine powder. Attempts have been made to improve the classification accuracy of classifiers attached to crushers. Although this has improved the above-mentioned problems,
However, due to the increase in the number of classification means and transportation means 5 from the first classification means to the third classification means, etc.
The process becomes complicated, the investment amount nearly doubles, and the first
There have been problems such as an increase in running costs due to the energy required to operate the classification means, transportation means, etc.

[Problem that the invention seeks to solve]

The present invention is intended to solve the various problems mentioned above in the conventional toner pulverization method, and its purpose is to provide a manufacturing method that can efficiently obtain toner for electrostatic development with a uniform and fine particle size distribution. It is in.

[Means for solving problems]

An object of the present invention is to 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 produce a pulverized raw material, and classify the generated pulverized raw material. In a method for producing toner powder, a pulverized raw material is introduced into a first classification means to be classified into a first coarse powder and a first classified fine powder, and the classified first coarse powder is introduced into a first pulverization means and pulverized. Then, the obtained pulverized first coarse powder is introduced into the first classification means together with the pulverized raw material and classified, and the classified first classified fine powder is passed through the second classified means consisting of the multi-divided classification means.
The second coarse powder is introduced into a classification means and classified into a second coarse powder, a second classified medium powder, and a second classified fine powder, and the classified second coarse powder is introduced into a second crushing means and crushed. 2. The pulverized material of coarse powder is introduced into a second classification means, the second classification means is composed of a multi-divided classification area divided into at least three by a classification fence,
A crushed product of the classified fine powder and the second coarse powder is introduced and lowered in a curved line, and the second coarse powder mainly composed of coarse particles is collected in the first fractionation area, and the second coarse powder is divided into the second fraction. The second classified powder, which is mainly composed of particles within a predetermined particle size range, is divided and collected in the divided area, and the second classified fine powder, which is mainly composed of particles with a predetermined particle size or less, is divided into the third fractionated area. An object of the present invention is to provide a method for producing a toner for developing an electrostatic image, which is characterized by collecting the toner.

The method of the present invention is for pulverizing a melt-kneaded coarse powder, and FIG. 1 is a flowchart showing an overview of the method. That is, in the method of the present invention, the crushed material crushed in the first crushing means is sent to the raw material and the first classifying means,
The first classification means classifies the powder into coarse powder and fine powder. The coarse powder classified by the first classification means is introduced into the first crushing means and is crushed. The fine powder classified by the first classifying means is further classified into three parts by the second classifying means, and the second classified coarse powder is crushed by the second crushing means and further sent to the second classifying means. On the other hand, a group of particles having a predetermined internal particle diameter of the second classified intermediate powder is taken out from outside the system as a finished product. Further, the second classified fine powder having a predetermined particle size or less is also taken out from outside the system.

The multi-division classification means used as the second classification means is disclosed in US Patent No. 4,132,6.
There are devices and means described in No. 34. For example, a multi-division classifier of the type shown in FIG. 4 (cross-sectional view) and FIG. 5 (stereoscopic view) can be exemplified as one specific example. In FIGS. 4 and 5, the side walls are 22. 23. 24, the lower wall has the shape 25, and the side wall 23 and the lower wall 25 are provided with knife-etched classification edges 17, 18, respectively, and the classification etch 17. 1
8, the classification zone is divided into three parts. A raw material supply nozzle 16 that opens into the classification chamber is provided at the lower part of the side wall 22,
A Coanda block 26 is provided which is bent downward in the direction of extension of the tangent to the bottom of the nozzle to draw an elongated arc. The upper wall 27 of the classification chamber is provided with a knife-etched edge 19 toward the bottom of the classification chamber, and furthermore, at the top of the classification chamber, there is a tube 14 that opens into the classification chamber. 15 is provided. In addition, the popular tubes 14 and 15 have a first tube like a Daipa. A second gas introduction regulating means 20.21 and a static pressure gauge 28.29 are provided.

Classification edge 17. The positions of 18 and popular edge 19 are
It varies depending on the type of raw material to be classified and the desired particle size. In addition, on the bottom of the classification chamber, there are discharge ports 11 that open into the chamber corresponding to each fractionation area. 12°13 is provided. Discharge port 11. 12. 13 may each be provided with an opening/closing means such as a valve means.

The raw material supply nozzle 16 consists of 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 1:1, preferably 10:1 to 2:1.
When set to 1, good introduction speeds (flow rates of 50 m/s to 300 m/s) are obtained.

Due to the Coanda effect, the supplied raw material moves in a curved line 30 due to the action of the Coanda block 26 and the action of gas such as air flowing in at that time, and depending on the size of each particle, large particles (coarse particles) are formed. Particles) are the fraction outside the airflow, that is, outside the classification edge 18, intermediate particles (particles within the specified particle size) are the fraction between classification edges 18 and 17, and small particles (particles below the specified particle size). The particles are divided into fractions inside the classification edge 17, and large particles are discharged from the discharge port 11, intermediate particles are discharged from the discharge port 12, and small particles are discharged from the discharge port 13.

In order to carry out the above-described method, it is usual to use an integrated equipment system comprising interconnected equipment by means of pipes or the like, and a preferred example of such equipment is shown in FIG.

The integrated apparatus shown in FIG. 6 includes a first crusher 3. 1st classifier 1
．． First classification cyclone 5° transportation injection feeder 103. Collection cyclone 105. 2nd classifier body 2. The second pulverizer 4° is constructed by connecting a second coarse powder cyclone 6 for classification, a second classification medium powder cyclone 7, and a second classification fine powder cyclone 8 through pipe means.

In this device, the so-called pulverized raw material is passed through a raw material inlet 100 and through a raw material supply conduit 101 to a first classifier.
The first classified coarse powder is introduced into the first pulverizer 3, is pulverized, and is again introduced into the first classifier 1 via the conduit 101.

On the other hand, the first classified fine powder obtained by classification passes through a conduit 102, is collected in a collection cyclone 5, is taken out from the cyclone by an injection feeder 103, and is taken out through a conduit 104,
It passes through the collection cyclone 105 and is introduced into the second classification means 2 where it is classified. The second classified coarse powder is collected by a collection cyclone 6 and crushed by a second crusher 4, and the second crushed product is passed through a conduit 114 and a collection cyclone 105 to the second classification means 2 for first classification. Introduced with fine powder. On the other hand, the second classified intermediate powder is collected by the collection cyclone 7 and discharged from the finished product discharge lower 1. Further, the second classified fine powder is collected by the collecting cyclone 8 and discharged from the fine powder outlet 81. Here, in the collection cyclone 105, the air volume control valve 1
09 and the tightening means 16 at the inlet of the first classifying means to control the wind m to introduce the powder and air into the second classifying means.

As the crushers 3 and 4, impact crushers, jet crushers, etc. can be used, but each must be capable of crushing to the desired particle size by itself. Micron's MVM crusher Turbo Kogyo's Turbo Mill, etc. Pulverizers that use jets include Nippon Pneumatics Industry's PJM-1, Micron's Micron Jet for wires, Jet-0-Mizer, and Blaw-K.
nox, Trost JetM i l 1,
Others are available. Further, as the first classifier 1, a DS separator manufactured by Nippon Pneumatics Industries, a turbo classifier manufactured by Nisshin Engineering, an MS separator manufactured by Micron for wires, and other classifiers can be used.

As the second classification means 2, a classification means having a Coanda block such as Nippon Steel Mining's Elbow Jet and utilizing the Coanda effect may be used.

〔Effect of the invention〕

As explained above, in the method of the present invention, when the second classification means is pulverized by the second pulverization means, only fine particles close to the retoner particle size are pulverized and sent to the classification, which is different from the conventional method. As a result, the generation of ultrafine powder of 2 μm or less and fine powder aggregates can be prevented, and a pulverized product with a sharp particle size distribution can be obtained. Furthermore, as the second classification means uses a specific classification means to remove coarse particles and fine particles at the same time, the classification step that was conventionally performed in the next step is no longer necessary, and particles within a predetermined particle size range can be quickly removed. Therefore, it is possible to efficiently obtain a particle group having a precise particle size distribution.

Furthermore, in the above-mentioned conventional classification process, the classification methods such as fixed wall classifiers and rotary classifiers used for the purpose of classifying medium-powder areas and fine-powder areas are the cause of fogging of developed images composed of fine particles. It is easy to form aggregates (if they occur, it is difficult to remove them from the medium-sized powder area), but according to the method of the present invention, even if aggregates are mixed in, the aggregates can be broken down by the Coanda effect and/or high-speed movement. In addition to being broken and removed as fine powder, even if there are aggregates that have escaped disintegration, they can be simultaneously removed to the coarse or fine powder area, making it possible to efficiently (remove) the aggregates and classify them. The yield can be improved satisfactorily.

Another effect of the present invention is that the impact force during crushing by the second crushing means is controlled to be weaker than the impact force during crushing by the first crushing means. The air pressure of the crushing air of the crushing means is 5 to 10K.
g/crrr, and the second crushing means has a crushing air pressure of 2 to 6 kg/crrr, which is lower than the air pressure of the crushing air of the first crushing means.
By pulverizing at a lower level compared to the above, it is possible to obtain a pulverized product with a sharper particle size distribution and less generation of fine powder or ultra-fine powder. In addition, products obtained by further processing the crushed products obtained by this method have good fluidity and image quality, which is higher in density than those made by conventional processes, and there is no burr in the ground or around the letters. You can get something with less dust.

Also, medium powder with small particle size (for example, average particle size 3 to 7μ)
The present invention can be carried out more efficiently than conventional methods when manufacturing.

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

Example 1 FIG. 6 shows an example in which the present invention was implemented, and the raw material used was a melt-kneaded cooled material for toner that was coarsely crushed using a hammer mill with a 3 mm screen. The first pulverizer 3 is a 1-10 type jet mill made by Nippon Pneumatic Industries, and the crushing pressure is set to 6 kg 1 crd, and the second pulverizer 4 is a 1-5 type jet mill, manufactured by Nippon Pneumatic Industries, with a crushing pressure of 4.5 kg. /ct+? It was set to . As the first classifier 1, DS-10 manufactured by Nippon Pneumatics Industry Co., Ltd.
Using a UR classifier, the particle size of the first classified fine powder is determined by a coulter.
The volume average diameter was set to 12 to 18 μm as measured by a counter.

As the second classification means 2, an Elbow Jet EJ-45-B type machine manufactured by Nippon Steel Mining Co., Ltd. is used, and the particle size of the second classified medium powder (toner powder) is set to 10 to 12 μm in volume average particle size by Coulter counter. I set it like this. The results are shown in Table 1.

Example 2 The same apparatus as in Example 1 was used, and as a raw material, a melt-kneaded cooled material for toner was coarsely crushed using a hammer mill with a 3 mm screen. The l-10 type jet mill of the first crusher 3 has a crushing pressure of 6 kg/crrr, and the I-5 type jet mill of the second crusher 4 has a crushing pressure of 5 kg/crrr.
It was set to . The particle size of the first classified fine powder of the DS-10UR type classifier of the first classifier 1 was set to be 10 to 14 μm in terms of volume average diameter measured by a Coulter counter.

The particle size of the powder during the second classification of the EJ-45-3 classifier, which is the second classification means, is 7 to 7 in terms of the volume average diameter measured by a Coulter counter.
The thickness was set to 9 μm. Table 2 shows the results.

Comparative Example 1 The same melt-kneaded coolant for toner as in Example 1 was used as the raw material for 3
Using coarsely crushed powder using a hammer mill with a mm screen,
Grinding and classification were carried out using a grinding-classifying system configured as shown in FIG. As a crushing means, a 1-10 type jet mill made by Nippon Pneumatic Kogyo was used with a crushing pressure of 6 kg/c.
It was used by setting it to rd. As the first classification means, a DS-IOUR classifier manufactured by Nippon Pneumatics Industries is used, and as the third and second classification means, a DS-5UR classifier manufactured by Nippon Pneumatics Industries is used. The particle size is 9 to 1 in volume average diameter by Coulter counter.
The particle size of the second classified coarse powder was set to 10 to 128 m in terms of volume average diameter measured by a Coulter counter. The results are shown in Table 1.

Comparative Example 2 The same melt-kneaded coolant for toner as in Example 2 was used as the raw material for 3
Using coarsely crushed powder using a hammer mill with a mm screen,
Using the same apparatus as in Comparative Example 1, pulverization and 9 classifications were performed. The L-10 type jet mill used as the crushing means has a crushing pressure of 6 kg/c.
It was used by setting it to rd. In the DS-5UR type classifier with the third classification means and the second classification means, the particle size of the third classification fine powder and the particle size of the second classification coarse powder are 6 to 8 μm and 7 to 9 μm in volume average particle size by Coulter counter, respectively. I set it to be. The results are shown in Table 2.

Table 1 *l) Based on Coulter counter.

*2) Ratio of the amount of finally obtained classified product to the total amount of raw materials supplied.

*3) Using the obtained classified product as a toner, a developer was prepared by mixing 0.3% by weight of hydrophobic silica, and the developer was supplied to a copying machine NP-1502 (manufactured by Canon) for a copying test. result.

Table 2 *l) Based on Coulter Counter *2) Ratio of the amount of finally obtained classified product to the total amount of supplied raw materials.

[Brief explanation of the drawing]

Fig. 1 is a flowchart of the present invention, Figs. 2 and 3 are flowcharts showing a conventional example, and Fig. 4 is a flowchart of the present invention.
5 and 5 are sectional views of an apparatus which is a specific example for carrying out the multi-division classification means of the present invention, respectively. Shows an elevation. FIG. 6 is a schematic diagram showing a crushing and classifying apparatus system for carrying out the method of the present invention.

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, a pulverized raw material is introduced into a first classification means to be classified into a first coarse powder and a first classified fine powder, and the classified first coarse powder is introduced into a first pulverization means and pulverized, and the obtained The pulverized first coarse powder is introduced into the first classification means together with the pulverized raw material and classified, and the first classified fine powder is passed through the second classification means, which is composed of a multi-divided classification means.
The second coarse powder is introduced into a classification means and classified into a second coarse powder, a second classified medium powder, and a second classified fine powder, and the classified second coarse powder is introduced into a second crushing means and crushed. 2. The pulverized material of coarse powder is introduced into a second classification means, the second classification means is composed of a multi-divided classification zone divided into at least three by a classification fence,
A crushed product of the classified fine powder and the second coarse powder is introduced and lowered in a curved line, and the second coarse powder mainly composed of coarse particles is collected in the first fractionation area, and the second coarse powder is divided into the second fraction. The second classified powder, which is mainly composed of particles within a predetermined particle size range, is divided and collected in the divided area, and the second classified fine powder, which is mainly composed of particles with a predetermined particle size or less, is divided into the third fractionated area. A method for producing a toner for developing an electrostatic image, characterized by collecting the toner.