JPS63112626A - Production of toner powder - Google Patents

Abstract

PURPOSE:To obtain a toner powder of a sharp particle size distribution in good efficiency, by feeding grinding feeds to 1st and 2nd classification means and to 1st and 2nd grinding means through specified routes and feeding the ground product of the coarse powder from the 2nd grinding means to the 1st classification means. CONSTITUTION:A powder feed is fed from a feed hopper 1 through a feed supply pipe 2 to a 1st classifier 3, and the classified coarse powder from the 1st classifier 3 is fed to a grinder 4, ground, and re-fed through the pipe 2 to the 1st classifier 3. On the other hand, the classified fine powder from the 1st classifier 3 is fed to a collection cyclone 6 and collected, withdrawn from the cyclone with an injection feeder 7, fed through a pipe 8 to a 2nd classifier 9 and classified. The classified coarse powder from the 2nd classifier 9 is reground in a 2nd grinder 13, and the ground product from the 2nd grinder is fed through a pipe 14 to the 1st classifier 3 together with the feed and the ground product from the 1st grinder. The coarse powder from the 2nd classifier 9 is ground with a 2nd grinder and is fed to the 1st classifier 3 together with the feed and the ground product from the 1st grinder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for efficiently producing toner powder with 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 passes through the crushing means, is pulverized, and is again introduced into the classification means. On the other hand, the fine powder is discharged out of the system as a δ′1 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 drawbacks.

Furthermore, due to the poor performance of the classifier, there is a problem that the energy efficiency of pulverization 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 second 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 second classification means,
There were problems such as the process became complicated, the investment doubled, and the running cost for the energy required to operate the first classification means, transportation means, etc. increased.

[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.

[Failure to solve the problem]

In the present invention, a composition containing at least a binder resin and a colorant is melt-kneaded, the kneaded material is cooled and solidified, the solidified material is pulverized to produce a pulverized raw material, and the produced pulverized raw material is mixed to produce toner powder. In the method for manufacturing, a pulverized raw material is introduced into a first classification means to be classified into a first coarse powder and a first divided powder, and the classified first coarse powder is introduced into a first pulverization means and pulverized. ,
The obtained pulverized first coarse powder is introduced into a first classification means together with the pulverized raw material and classified, and the classified first powder is introduced into a second classification means to form a second coarse powder and a second classified fine powder. The classified second flour is introduced into a second crushing means and crushed,
The method for producing toner powder is characterized in that the obtained pulverized second coarse powder is introduced into a first classification means.

The method of the present invention is for pulverizing a melt-kneaded coarse material, and FIG. 1 is a flowchart showing an overview of the method.

That is, in the method of the present invention, the pulverized material and the raw material crushed in the first crushing means and the second crushing means are sent to the first classifying means, and the coarse powder classified by the first classifying means is sent to the first crushing means. introduced and crushed.

The fine powder classified by the first classification means is further classified by the second classification means, the second classified coarse powder is crushed by the second crushing means, and is further sent to the first classification means together with the raw material and the crushed product of the first crushing means. be introduced.

On the other hand, the second classified fine powder is discharged out of the system as a pulverized product.

To carry out the above-mentioned method, it is usual to use an integrated device system in which devices are connected to each other by vibrating means or the like, and a preferred example of such a device is shown in FIG. The integrated device shown in FIG. 4 includes a first crusher 4, a first crusher 3,
A first classification cyclone 6, an injection feeder 7 for transportation, a second classifier 9, a second crusher 13, and a second classification cyclone 11 are connected by pipe means.

In this device, a so-called powder raw material is introduced into a first classifier 3 through a raw material inlet 1 and a raw material supply conduit 2, and the first classified coarse powder is introduced into a crusher 4. It is crushed and introduced into the first classifier 3 via the conduit 2 again.

On the other hand, the first classified fine powder obtained by classification passes through a conduit 5, is collected into a collection cyclone 6, is taken out from the cyclone by an injection feeder 7, is introduced into a second classification means 9 via a conduit 8, and is classified. Ru. The second classified coarse powder is pulverized by the second pulverizer 13, and the second pulverized product is passed through the conduit 14.
It is then introduced into the first classifier 3 together with the raw material and the first pulverized product.

On the other hand, the second classified fine powder is collected by a conduit 10 and collected by a cyclone 1.
1 and discharged from the pulverized product outlet 12.

As the crushers 4 and 13, an impact crusher, a jet crusher, etc. can be used, but each must be capable of crushing to the target particle size by itself. MVM crusher made by Enmicron, and crushers using jets include Shiraki Pneumatic Kogyo and PJ.
Micron jet or Jet-0 made by Micron for M-1° line
-Mizer, Blaw-Knox, TrostJet
Mill, and others are available.

As the classifications 8a3 and 9, DS separator manufactured by Shiraki Pneumatic Industries, turbo classifier manufactured by Nisshin Engineering, MS separator manufactured by Micron for wires, and other classifiers can be used.

According to the present invention, compared to conventional equipment, the investment cost is only the addition of a small crusher (about 10%).
It is possible to significantly increase processing capacity by 50% to 100%. In terms of power, the electric power of the second crushing means 5 is increased compared to the conventional example (FIG. 3), but the electric power of the classifying means, etc., which uses a large amount of electric power, does not change, so the developer is mixed up. In terms of power consumption per unit weight, significant energy savings of 15% to 30% are possible.

Another effect of the present invention is that when the toner is crushed by the second crushing means from the second classification means, unlike the conventional method, only fine particles close to the toner particle size are crushed and sent to the classification. , over-pulverization is prevented, 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. In the next step, classification is performed and 7 to 8μ
The yield of the classified product when removing fine powder of m or less is also improved by 3 to 5%, and the presence of ultrafine powder and fine powder in the classified product is also small.

Further, in the present invention, it is necessary that the second classifying means and the second crushing means use devices having a processing capacity equal to or lower than that of the first classifying means and the second crushing means, respectively. That is, the second classification means and the second crushing means are usually 1/1 to 1/1 compared to the first classification means and the second crushing means.
It is preferable to use a device with a processing capacity of 1/3, and using a large device is not advantageous in terms of energy efficiency and results in a broad particle size distribution.

Another effect of the present invention is that the turbidity force during crushing of the second crushing means is weaker and controlled than the impact force during crushing of the first crushing means. The air pressure of the crushing air of the first crushing means is set to 5 to 1
0 kg/cm2, and the second crushing means uses 2 to 6 kg/cm2, which is lower than the air pressure of the crushing air of the first crushing means.
By pulverizing at a lower level than cm 2 , 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, the products obtained by further processing the crushed products obtained by this method have good fluidity, image quality, and density are higher than those made by conventional processes, and they have less soil burr, You can also get one with less clutter around the letters.

In addition, in order to make the present invention more effective, it is important to use means for preventing pulsation of the powder sent to the second classification means. As shown in the figure, the discharge double damper 21 discharges the fine powder under the first classification cyclone 6, and the feeder 15 receives and supplies the discharged first class fine powder in a fixed quantity. A method of dispersing and sending the particles to the second classification means 9 will be exemplified.

Here, the feed amount of the feeder 15 is set to 1.0 to 1.5 times, preferably 1.1 to 1.3 times, the amount of powder sent through the first classification cyclone 6, and the level meter 16
Accordingly, when the first classified fine powder in the feeder 15 is not detected, the feeder 15 is stopped, and when it is detected, the feeder 15 is operated. Further, as a further example of means for preventing pulsation, as shown in Fig. 6, a restricting means is provided at the supply ports of the powder supplied to the first and second crushing means, so that a large amount of powder can flow. It is also effective to use this as a means to prevent this.

The present invention will be explained in detail in Examples below.

[Example 1] FIG. 5 shows an example in which the present invention was carried out, and the raw material used was a developer mixture coarsely crushed using a hammer mill with a 3 mm screen. The crusher 4 is a type l-10 jet mill made by Nippon Pneumatic Industries, and the crushing pressure is 6 k.
g/cm', and the crusher 13 used was a type I-5 jet mill manufactured by Nippon Pneumatic Industries, with the crushing pressure set at 4.5 kg/am2. The classifier 3 is manufactured by Nippon Pneumatic Kogyo, DS-10 type
Using a L machine, the amount of classification air is 20 m3/m, and the particle sizes of the first classified coarse powder and the first classified fine powder are 30 to 50 μm and 15 to 30 μm, respectively, as volume average diameters measured by a coulter counter.
For the 0 classification m9 set to be μm, a DS-5 classifier manufactured by Nippon Pneumatic Kogyo was used, the classification air amount was 10 m'/m, the second classification coarse powder and the second classification fine powder (pulverized product) particle size were set to have an average deposition diameter of 20 to 35 μm and 10 to 12 μm, respectively, as measured by a Coulter counter, and the results shown in Table 1 were obtained.

3 Cohesion Degree The method for measuring the cohesion degree used in the present invention is to place toner on a sieve, apply vibrations, and measure the proportion of toner remaining on the sieve.

According to this method, the greater the proportion of toner remaining on the sieve, the greater the degree of toner aggregation, indicating that toner particles tend to aggregate and behave. Specifically (temperature 25 ± 1 using a powder tester manufactured by Micrometix Laboratory for
Measured under the conditions of ℃ and humidity of 60 degrees and 5%.

Line up sieves of 60 mesh, 100 mesh, and 200 mesh in this order from above and set them on a shaking table. 2 g of toner was set on a 60-mesh sieve, and a voltage of 47 V was applied to a vibration meter to give vibration for 40 seconds.

After finishing, measure it of the toner remaining on each sieve, add weights of 0.5, 0.3, 0.1 to each,
The degree of aggregation is expressed as a percentage.

(Example 2) Figure 4 shows an example of implementing the present invention, and the raw materials are:
The developer kneaded material was coarsely crushed using a hammer mill with a 3 mm screen. The crusher 4 is a type L-10 jet mill made by Nippon Pneumatic Industries, and the crushing pressure is 6 kg.
/cm2, and the crusher 13 is a type I-5 jet mill manufactured by Nippon Pneumatics Industries, and the crushing pressure is set to 5.
kg/cm". As the classifier 3, a wire type Micron MS-3 classifier was used, and the particle size of the first classified coarse powder and the first classified fine powder was , respectively, were set to have a volume average diameter of 30 to 50 μm and 115 to 30 μm as determined by a coulter counter.The classifier 9 used was a wire type Micron MSS-1 classifier, the amount of classification air was 15 m3/m, and the second coarse classification The particle size of the powder and the second classified fine powder (pulverized product) was determined to be 20 to 35μ by volume average diameter by Coulter counter.
The results shown in Table 2 were obtained by setting the thickness to 10 to 12 μm.

[Brief explanation of the drawing]

Fig. 1 is a flowchart of the present invention, Fig. 2 is an example of a conventional example (Fig. , 19 is a double damper 20 for taking out and discharging the coarse powder from the second classification means 9, and a chute for sending the second classified coarse powder to the crusher. In FIG. 6, 22 is the main body of the crusher, 23 is the hopper of the crusher, 24 is a conical throttle valve attached to the powder supply port, and 25 is an air ejector 126 that accelerates the powder with high-pressure air. causes accelerated powder to collide,
The collision plate 27 for crushing powder is a discharge port for powder and air.

Claims (1)

[Scope of Claims] A composition containing at least a binder resin and a colorant is melt-kneaded, the kneaded material is cooled and solidified, the solidified material is pulverized to produce a pulverized raw material, and the produced pulverized raw material is classified. 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 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 powder is introduced into the second classification means and divided into the second coarse powder and the second coarse powder. The method is characterized by: classifying the classified second coarse powder into a classified fine powder, introducing the classified second coarse powder into a second crushing means and pulverizing it, and introducing the obtained crushed second coarse powder into the first classifying means. Method of manufacturing toner powder.