JP2001205069A - Mixer for powder and granular material and method for producing toner for developing electrostatic image using mixer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of large-size particles caused by pressing with a discharge valve in the vicinity of the discharge opening of a mixer for powder and granular material by preventing the adhesion of the material near the discharge opening when the discharge opening is opened and closed. SOLUTION: In the mixer having the discharge opening with a part of the bottom part of a mixing tank made the openable/closable discharge valve and a discharge mechanism which makes the valve attach/detach to/from the inner wall of the discharge opening or the bottom part of the mixing tank for opening/closing operation, a mechanism which cleans the valve or a part to be pressed on the periphery of the discharge opening of the mixing tank which is engaged with the valve when the valve is pressed by compressed air synchronously with the opening/closing operation is provided. In a method for producing a toner for developing an electrostatic image, the mixer is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a powder such as an electrostatic image developing toner used for developing an electrostatic latent image formed by an electrophotographic system or an electrostatic recording system.

[0002]

2. Description of the Related Art Conventionally, a method for producing a toner used in electrophotography such as electrophotography and electrostatic recording is to mix, melt and knead materials such as a binder resin and a colorant, and to use a compressed gas after cooling. After crushing finely with a crusher such as a jet mill, the particles are sized to the desired size using a classifier that uses the flow of airflow, and additives are added as necessary, and filled into containers such as bottles and cartridges. Is done.

[0003] Among these steps, in the external addition step of adding an additive close to the final step, it is inevitable to adopt a batch method. Therefore, the discharge valve is operated for each batch to perform the external addition step. After the contents are discharged, it is repeatedly performed to close the outlet and prepare for the next processing.

[0004] After the completion of this one batch, the powder particles remaining at the discharge port of the mixer are sandwiched between the discharge port and the minute space of the discharge valve when the discharge valve is closed and adhered, and peeled off during repeated processing several times. They are mixed into the mixture to form coarse particles. Therefore, it is necessary to periodically clean the fitting portion between the discharge valve and the discharge port.

Usually, it is preferable that the discharge channel including the discharge port of the mixing tank and the driving path of the cylinder are collectively enclosed in a box in one room in order to prevent scattering of powder.

For this reason, it is necessary to open the inspection port at the upper part of the discharge valve box and clean the discharge valve and the discharge port, and the cleaning work involves danger, and the cleaning operation is performed by opening and closing the inspection port each time. Work is reducing production efficiency.

[0007]

The powder particles slightly remaining at the discharge port, the bottom of the mixing tank and the discharge valve of the powder / particle mixer for batch processing as described above are discharged by opening / closing the discharge valve between batches. It is unavoidable that the inner wall of the outlet or the bottom of the mixing tank is interposed and fixed between the minute space of the discharge valve, and a mechanism for preventing the powder particles from being fixed at the discharge portion is required.

Particularly in the field of toner production, the incorporation of coarse particles greatly affects quality problems and must be avoided. On the other hand, it takes enormous time and effort to remove the coarse particles once mixed.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a mixer for powder and granules capable of suppressing generation of coarse particles.

Further, an object of the present invention is to solve the above-mentioned problems of the prior art, to greatly reduce the frequency of cleaning the discharge portion of the powder-granule mixer and to avoid danger, thereby reducing the electrostatic charge image. An object of the present invention is to provide a method for efficiently producing a developing toner.

[0011]

That is, the present invention relates to a process for producing a powder such as an electrostatic image developing toner used for developing an electrostatic latent image formed by an electrophotographic system or an electrostatic recording system. A powder-fluid mixer having a mixing tank used for stirring and mixing, wherein a part of the bottom of the mixing tank is a discharge valve that can be opened and closed by an external cylinder, and the discharge valve is press-fitted and detached. A powder-fluid mixer having a discharge mechanism for performing an opening / closing operation, preferably having a structure in which a discharge port thereof is connected to a discharge valve box, and an inner wall of the discharge port and the mixing tank when the discharge valve is crimped; The present invention relates to a powder-fluid mixer for cleaning a bottom portion to be pressed with compressed gas, and further relates to a method for producing a toner for developing an electrostatic image using the mixer.

More preferably, the compressed gas is supplied to an annular hollow pipe provided in the vicinity of the outlet opening, and the compressed gas is ejected from an outlet provided on the outer wall of the annular pipe. And a method of manufacturing a toner for developing an electrostatic charge image using the same, wherein the inner wall of the discharge opening, the bottom of the mixing tank and the discharge valve are fitted in a clean state.

[0013]

The powder fluid mixer described in the present invention is a mixer having a mixing means such as a mixing tank and a stirring blade, and is used for stirring and mixing of powder and granules.

The discharge port is provided at the bottom of the mixing vessel. The discharge port is formed by cutting out a part of the inner wall of the mixing vessel, and the discharge port is closed as it is. In the closed state, it functions as a part of the inner wall of the mixing vessel. With this discharge valve, the powder fluid in the mixing tank is dropped and discharged mainly by gravity. Since the discharge valve functions as the inner wall of the mixing tank during operation of the powder-fluid mixer, it is preferable that the discharge valve be pressurized tightly to the opening of the discharge port or the bottom of the mixing tank with a compressed gas or the like.

The compressed gas jet nozzle formed by the annular pipe has an inner diameter of the ring larger than an outer diameter of the discharge valve and a size that does not hinder the opening / closing operation of the discharge valve. Is preferred. With such a size, when the discharge valve is driven in a direction parallel to the discharge port opening axis to perform the opening / closing operation, it is necessary to perform the crimping and demounting operation of the discharge valve through the ring. It is possible to efficiently clean the discharge valve during the closing operation of the discharge valve.

[0017] The annular pipe is in a cylinder path,
It is installed near the bottom of the mixing tank and the opening of the discharge port so that the axial direction of the opening substantially coincides with the opening of the discharge port. Preferably, the compressed gas to be ejected is ejected substantially in the axial direction of the annular pipe, preferably in both directions, so that both the ejection opening and the open discharge valve can be cleaned simultaneously.

[0018] For this purpose, the spouts installed on the outer wall of the annular pipe should be installed at appropriate intervals and in appropriate directions around the axis of the annular pipe along the circumference of the annular shape. However, the outlet may be provided in a continuous slit shape. Furthermore, since the annular pipe is larger than the discharge valve, it is preferable to install the compressed gas so that the compressed gas is ejected in a direction converging on the center axis of the annular pipe.

Further, using such a compressed gas ejection mechanism, a compressed gas is introduced from the outside and ejected from the ejection port until the closing operation is completed in synchronization with the closing operation of the discharge valve. While the closing operation is completed in synchronization with the closing operation, the powder adhering to the discharge valve, the discharge port, and the portion to be pressed on the bottom of the mixing tank is cleaned and removed. In addition, the timing of the compressed gas ejection may be performed before the closing operation of the discharge valve starts,
When the discharge valve is operated, the compressed gas is ejected to the discharge valve from different directions, so that more effective cleaning can be performed.

That is, the compressed gas ejected from the outlet of the annular pipe is sprayed on one side to the inner wall of the outlet and the portion to be pressed on the bottom of the mixing tank to clean this portion, and on the other hand, the exhaust gas which has started the closing operation It is sprayed on the crimped part of the valve to clean this part.

The gas to be ejected is generally air, but may be nitrogen gas or other inert gas.
If necessary, the temperature of the ejected gas can be controlled in advance according to the characteristics of the powder fluid mixed and stirred.

As described above, the powder-granule mixer according to the present invention shifts to the next mixing operation after the powder-granules are agitated and mixed and the mixture is discharged, and before the discharge valve is fitted to the discharge port again. As a preparation, the compressed gas can be ejected from a compressed gas ejection nozzle installed very close to the discharge port, so that the discharge valve and the discharge port can be fitted together while being cleaned at the same time. Therefore, unlike the conventional case where the discharge port and the discharge valve are fitted with the particulate matter remaining in the discharge port and the discharge valve, the discharge port and the discharge valve can always be fitted in a clean state. There is no biting of the body and no sticking matter. Therefore, when the same powder and granules are continuously mixed, there is no need for cleaning work with the opening of the inspection port of the discharge valve box as in the prior art, so there is almost no danger and further continuous work is possible. Therefore, production efficiency is also improved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following inventions and embodiments of the present invention are included. In particular, the invention includes the following.

1. In a powder fluid mixer for the purpose of stirring and mixing powder fluid, an outlet as a discharge valve capable of opening and closing a part of the bottom of the mixing tank of the mixer, and the discharge valve being press-fitted to and detached from the bottom of the mixing tank. It has a discharge mechanism that opens and closes at least,
A powder-fluid mixer wherein the discharge valve, the inner wall of the discharge port, and a portion to be pressed at the bottom of the mixing tank are cleaned with a compressed gas at the time of pressing in conjunction with the closing operation of the discharge valve.

2. The discharge mechanism is characterized in that the discharge valve is driven by a cylinder in the axial direction of the opening of the discharge port, and the opening and closing operation is performed by pressing and detaching the discharge valve on the inner wall of the discharge port or the bottom of the mixing tank. 2. The powder-fluid mixer according to the above 1, wherein

3. A compressed gas ejection nozzle having an ejection port or an ejection slit installed on the outer wall of a hollow ring whose inner diameter is larger than the outer diameter of the discharge valve is connected to a compressed portion or a mixing tank of the discharge port inner wall in the middle of the drive path of the discharge valve. 3. The powder-fluid mixer according to the above item 2, wherein the powder-fluid mixer is installed close to a portion to be pressed on the bottom.

4. The spout provided on the outer wall of the hollow ring has a circumference centered on the axis of the ring, and the axis of the ring is set on a circumference coinciding with the axis of the circumference. 4. The powder-fluid mixer according to the above item 3, wherein

5. A mixture containing at least a binder resin and a colorant is melt-kneaded, the kneaded product is cooled and solidified, the solidified product is pulverized, the pulverized product is classified, and an additive is externally added to the classified powder to electrostatic charge. A method for producing a toner for developing an electrostatic image, comprising using the powder / particle mixer according to the above 1, 2, 3, or 4 in the external addition step.

One embodiment of the present invention will be described below.

The powder-granule mixer of the present invention has a mixing tank for the purpose of stirring and mixing, and a discharge tank provided at the bottom of the mixing tank with a discharge valve which is a part of the bottom and can be opened and closed by an external cylinder. Having an outlet, preferably the outlet is a powder discharge path,
A particulate mixer having a structure connected to a discharge valve box, which is a box-shaped enclosure that covers the entire drive path of the discharge valve, wherein an opening / closing of the discharge valve is larger than the discharge valve in the vicinity of the discharge port. Provide a compressed gas ejection nozzle consisting of an annular hollow pipe with an ejection port on the periphery of the extent that does not hinder the operation, and synchronize with the closing operation of the discharge valve, while the closing operation is completed, from the outside This is a powder fluid mixer having a function of introducing a compressed gas and ejecting it from an ejection port, and fitting the exhaust gas and the exhaust valve in a clean state.

FIG. 1 is a schematic structural view of an example of such a powder-particle mixer, FIG. 2 is a partial view of a discharge section, and FIGS. 3 to 6 show a compressed gas ejection nozzle. Was.

Here, the compressed gas outlet can be a small-diameter outlet (FIG. 3) or a slit-shaped outlet (FIG. 4, FIG. 5, or FIG. 6). Can be used.

The details of the operation of the toner external addition step using the powder-fluid mixer according to the present invention are as follows. That is, a predetermined amount of the classified granules is charged from the main material input port 1 and the lid is fixed, and a predetermined amount of the additive is charged at once or dividedly from the additive input port 2 and the lid is fixed. The stirring and mixing process is performed at a preset rotation speed and stirring time. afterwards,
After the stirring blade has stopped, the discharge valve driving air cylinder 11 is operated to open the discharge valve, and the mixture is discharged from the mixing tank 3 through the discharge valve box 5 in the direction of the external arrow. The powder particles remaining in the mixing tank 3 are discharged to the outside by rotating the stirring blade at a low speed with the discharge valve 12 being open. When the discharge operation is completed and it is confirmed that the stirring blade has stopped, the discharge valve driving air cylinder 11 is operated to close the discharge valve. In the meantime, a hollow annular compressed gas jetting annular nozzle 1
4, the compressed gas is ejected from the exhaust port 13 and the exhaust valve 12.
To clean.

On the other hand, the discharge valve is driven in a direction parallel to the axis of the discharge port, passes through an annular compressed gas jet nozzle, and is pressed against the inner wall of the discharge port or the bottom of the mixing tank.

In the case where the annular compressed gas ejection nozzle disposed in the vicinity of the discharge port has a small-diameter ejection port, the normal of the ejection port installed in the annular compressed gas ejection nozzle and the axis of the annular ring. And preferably has an angle of 10 to 80 degrees, and has a diameter of 0.2 mm to 3.0 mm, preferably 0.5 mm to 2.0 mm, A portion close to the gas introduction portion is small, and preferably four to sixteen small diameter nozzles are provided on one side of the ring as the distance increases. On the other hand, in the case of a slit-shaped jet port, the opening position is not unique due to the shape of the slit, but compressed gas is jetted in both directions with respect to the annular surface axis as in the case of the small diameter jet port, and the discharge port and An outlet is provided so that both discharge valves passing through the annular nozzle can be cleaned.

With respect to such a compressed gas ejection nozzle, the compressed gas introduced from the compressed gas generation source 10 is opened from the time when the closing start signal is received by the solenoid valve 9 to the time when the closing completion signal is received. The pressure is adjusted from 0.1 MPa to 0.6 MPa, preferably from 0.3 MPa to 0.5 MPa by the pressure control valve 8, introduced into the annular compressed gas ejection nozzle 14 through the compressed gas introduction unit 7, and discharged from the ejection port. The powder is sprayed in both directions of the outlet opening, the bottom of the mixing tank and the discharge valve to be closed, and the powder remaining at the discharge port, the bottom of the mixing tank and the portion to be pressed of the discharge valve is cleaned.

Since the thus-cleaned discharge port and the discharge valve are fitted to each other, there is no generation of a press-bonded material due to the fine particles being sandwiched in the minute space between the discharge port and the discharge valve.
In addition, since the cleaning work by opening the inspection port 6 of the discharge valve box is eliminated, dangerous work can be eliminated. Furthermore, since the mixing operation can be performed continuously, the production efficiency can be improved.

In the toner and the production method using the mixer according to the present invention, the constitutions other than those specified in the present invention or the steps in the production method are not particularly limited, and known constitutions and methods are used. . The mixing step is, for example, a mixing step of mixing auxiliary agents such as a charge control agent and a release agent in addition to a binder resin and a colorant. A kneading step of melt-kneading the mixture.
After cooling the melt-kneaded material, coarsely pulverized by appropriate means as necessary,
A pulverizing step of finely pulverizing with a pulverizer such as a jet mill using a compressed gas. A classifying step in which the pulverized toner is further adjusted to particles of a desired size by a classifier or the like utilizing an air flow. The method further includes an external addition step of adding an additive to the toner as needed, and a filling step of filling the container such as a bottle or a cartridge with the toner.

The mixer according to the present invention can be used in a pre-mixing step of mixing a binder resin, a colorant, an antistatic agent, a release agent, and the like, or an external addition step of mixing additives. It is particularly useful when used as a mixer.

The toner used in the present invention is not particularly limited and may be a known toner. Examples of the binder resin include polystyrene, styrene-acrylate copolymer, polyester resin, epoxy resin, butyral resin, and the like. Xylene resin, coumaroindene resin, and the like. As the colorant, for example, as a black pigment, carbon black, furnace black, aniline black, etc.
Benzidine pigments (CI291090, CI291095) and the like as yellow pigments for full-color toners, xanthene pigments (astrakunoxin) as red pigments,
Blue pigments include phthalocyanine pigments (CI Pigment Blue 15, CI Solvent Blue 70), and thioindigo pigments (CI78865) and azo lake pigments (CI15850).

Nigrosine dyes, quaternary ammonium salts, triphenylmethane dyes and the like are known as charge control agents for the purpose of imparting a positive charge. Used are acid dyes containing a heavy metal such as Cr.

Further, in heat roll fixing applications, various waxes are used as necessary as an anti-offset auxiliary agent for enhancing the releasing effect, for the purpose of preventing troubles due to toner adhesion to the heat roll. Natural waxes such as ester waxes, polyolefin waxes such as high pressure polyethylene and polypropylene can be used.

The mixing ratio may be, for example, 100 parts by weight of the binder resin as described above and 100 parts by weight of the coloring agent.
15 parts by weight, 0.1 to 5 parts by weight of a charge control agent, and 0.5 to 10 parts by weight of an anti-offset agent can be used.

Further, if necessary, 0.01 to 10 parts by weight of inorganic fine particles as a fluidity additive can be used.

The powder / particle mixer of the present invention and a method for producing a toner for electrostatic charge development using the same will be described with reference to the following Examples, but the present invention is not limited thereto.

Example 1 Styrene-acrylic copolymer 100 parts by weight (softening point; 110 ° C., glass point transfer; 60 ° C.) Carbon black 10 parts by weight Polypropylene 4 parts by weight Cr-containing dye 2 parts by weight

The above components were mixed, melt-kneaded in a twin-screw extruder, cooled immediately, crushed to 1 mm to 2 mm by a coarse crusher, and then subjected to fine crushing, classification, and external addition to 10 μm. The toner was created. In this step, a powder / granule mixer according to the present invention was used as a mixer in the external addition step.

In the powder-granule mixer, a pipe having a diameter of 10 mm as shown in FIG. 3 is formed into an annular shape so as not to hinder the driving of the discharge valve. Installed in On the side facing the outlet opening of the annular compressed gas ejection nozzle, around the axis of the ring, on the circumference around the axis, the normal of the injection port is 30 degrees to the axis of the ring. The ejection port is formed so as to have an angle of .ANG., And the ejection port is formed on the opposite surface of the discharge port so as to have an angle of 45.degree. 1mm in diameter near the compressed gas introduction side
An annular compressed gas jet nozzle having a total of 12 small-diameter jet ports 1.5 mm in diameter opened on one side was installed at a position far from the discharge port as shown in FIG.

The conditions for using the powder and particle mixer are as follows:
In addition to the normal mixing-discharging work cycle, the solenoid valve 9 is connected between the time when the discharge valve enters the closing operation and the time when the discharge valve is fitted with the discharge port.
Was set to be open, and the compressed gas with the original pressure of 0.8 MPa was used after being reduced to 0.4 MPa by the pressure control valve 8.

When the thus-prepared mixer was used, the discharge port and the discharge valve were visually observed from the inspection port of the discharge valve box every two batches from the start of the external addition process.
Even after the 50 batch processing, no generation of crimped material was observed at the discharge port and the discharge valve.

(Comparative Example 1) Except for using the powder / particle mixer of the present invention in the external addition step and changing the solenoid valve 9 so as not to operate to prevent compressed gas from entering the compressed gas ejection nozzle. In the same manner as in Example 1, an electrostatic image developing toner was manufactured. Visual observation from the inspection port of the discharge valve box in the external addition step revealed that, in the second batch, a press-bonded product of the toner was already detected in the discharge port and the discharge valve.

[0052]

According to the present invention, the use of the powder / granule mixer having the function of cleaning the powder with the compressed gas described in the present invention as a mixer for the externally adding step of the toner for developing the electrostatic image and the like enables the use of the discharge valve. The generation of coarse particles due to the pressing of the powder can be suppressed. In addition, there is no need to clean the discharge port and the discharge valve when the inspection port 6 is opened in the production of the same product, and it is possible to eliminate the operational danger associated with cleaning.

[Brief description of the drawings]

FIG. 1 is a schematic overall view of a mixer according to the present invention.

FIG. 2 is a view showing a positional relationship of an annular nozzle for ejecting compressed gas with respect to a discharge portion of the mixer according to the present invention.

FIG. 3 is an annular compressed gas ejection nozzle according to the present invention;
It is a figure showing an example which has a spout.

FIG. 4 is an annular compressed gas ejection nozzle according to the present invention;
It is the figure which showed an example which has an ejection slit.

FIG. 5 is an annular compressed gas ejection nozzle according to the present invention;
It is the figure which showed an example which has an ejection slit.

FIG. 6 is an annular compressed gas ejection nozzle according to the present invention;
It is the figure which showed an example which has an ejection slit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main raw material inlet 2 Additive inlet 3 Mixing tank 4 Motor 5 Discharge valve box 6 Inspection port 7 Compressed gas introduction part 8 Pressure control valve 9 Solenoid valve 10 Compressed gas generation source 11 Air cylinder for discharge valve drive 12 Discharge valve 13 Discharge port 14 Annular compressed gas jet nozzle

Claims (5)

[Claims] 1. A powder-fluid mixer for agitating and mixing powder-fluid, wherein a discharge port having an openable / closable discharge valve at a part of the bottom of the mixing tank of the mixer, and the discharge valve is connected to the mixing tank. It has a discharge mechanism that presses and attaches and detaches to the bottom and performs opening and closing operations, and in conjunction with the closing operation of the discharge valve, pressurizes the discharge valve, the inner wall of the discharge port, and the portion to be pressed on the bottom of the mixing tank at the time of pressing. A powder-fluid mixer, characterized in that it is cleaned with a liquid. 2. A discharge mechanism, wherein a discharge valve is driven by a cylinder in the axial direction of an opening of a discharge port, and the discharge valve is press-fitted to and detached from an inner wall of the discharge port or a bottom of a mixing tank to perform an opening / closing operation. The powder-fluid mixer according to claim 1, wherein: 3. A compressed gas ejection nozzle having an ejection port or an ejection slit installed on an outer wall of a hollow annular ring having an inner diameter larger than the outer diameter of the discharge valve is provided on an inner wall of the discharge port in the middle of a drive path of the discharge valve. 3. The powder-fluid mixer according to claim 2, wherein the pressure-fluid mixer is installed close to a crimping portion or a portion to be crimped at the bottom of the mixing tank. 4. A jet port installed on an outer wall of a hollow ring,
4. The circumference according to claim 3, wherein the circumference has a center on the axis of the ring, and the axis of the ring is set on a circumference coinciding with the axis of the circumference. Powder fluid mixer. 5. A mixture containing at least a binder resin and a colorant is melt-kneaded, the kneaded product is cooled and solidified, the solidified product is pulverized, the pulverized product is classified, and the additive is added to the classified powder. In a method for producing a toner for developing an electrostatic charge image by adding
5. A method for producing a toner for developing an electrostatic image, comprising using the powder / particle mixer according to claim 1, 2 or 3 in the external addition step.