JP7580966B2 - Grinding machine for toner production and manufacturing method - Google Patents

Description

The present invention relates to a pulverizer and a manufacturing method for producing toner used in electrophotography, an image forming method for visualizing electrostatic images, and a toner jet.

In electrophotography and image forming methods for visualizing electrostatic images, toners are used to develop electrostatic images. Toner manufacturing methods are roughly divided into pulverization and polymerization, and pulverization is a simple manufacturing method. In a general manufacturing method using the pulverization method, a binder resin and a colorant, and optionally a charge control agent, a release agent, a fluidity imparting agent, and a magnetic material are added and mixed, melted and kneaded, cooled and solidified, and then the kneaded material is pulverized by a pulverizing means. Thereafter, if necessary, a process of classifying the particles to a desired particle size distribution and a process of adding a fluidizing agent are carried out to obtain a toner to be used for image formation. In the case of a toner used in a two-component development method, the toner is mixed with various magnetic carriers and then used for image formation.
As the pulverizing means, various pulverizing devices are used, but in recent years, energy saving of the device is required in response to the reduction of _CO2 emissions, and mechanical pulverizers with low power consumption are often used.For example, a mechanical pulverizer is known that includes a rotor supported by a central rotating shaft and having a plurality of convex parts and concave parts on its outer circumferential surface in a casing having an inlet and an outlet of the material to be pulverized, and a stator disposed on the outside of the rotor with a predetermined gap from the outer circumferential surface of the rotor and having a plurality of convex parts and concave parts on its inner circumferential surface, and when the material to be pulverized passes through a processing section where the rotor and the stator face each other on the air flow flowing from the inlet to the outlet, it collides with the convex parts or concave parts of the rotor or the stator to pulverize the material to be pulverized.
In recent years, there has been a demand for smaller toner particles to improve image quality. In order to achieve this, it is effective to rotate the rotor at high speed in the mechanical grinding machine. For this purpose, Patent Document 1 proposes to lubricate the bearings at both ends of the central rotating shaft using an oil-air system.

JP 2002-1142 A

However, it has been found that the mechanical crusher described in Patent Document 1 has room for improvement in terms of stability of the bearing function in the high rotation speed range.
There are two types of lubrication for bearings: grease lubrication and oil lubrication, but oil lubrication is more advantageous for high-speed rotation. Oil circulation can withstand high speeds and certain temperatures, and is also effective in reducing bearing vibration and noise, so it is used in many situations where grease lubrication cannot solve the problem.
There are various types of oil lubrication, including oil bath lubrication, drop lubrication, splash lubrication, forced circulation lubrication, jet lubrication, oil mist lubrication (spray lubrication), oil/air lubrication, etc. Among these, forced circulation lubrication and jet lubrication are suitable for rotating heavy objects such as the rotors of crushers at high speeds because of the large amount of oil supplied and the high cooling capacity.
In the configuration of Patent Document 1, the amount of oil applied is so small that it does not exhibit a sufficient function of suppressing the rise in bearing temperature under high speed rotation conditions.
The present invention has been made to solve the above-mentioned problems. In other words, to produce small particle toner particles, it is necessary to rotate the rotor at high speed, but in conventional mechanical crushers, the lubricating function of the bearings is insufficient, and the device cannot operate stably for a long period of time. The present invention solves the above-mentioned problems and provides a crushing device necessary for producing small particle toner.

The present invention relates to a powder feeder having a powder inlet and a powder outlet,
A stator having a plurality of protrusions and recesses on an inner circumferential surface thereof;
a rotor attached to a central rotating shaft and having a plurality of protrusions and recesses on an outer circumferential surface;
A pulverizer for producing toner, comprising:
The stator contains the rotor, and the rotor is disposed so that a surface of the stator and a surface of the rotor face each other with a predetermined gap therebetween;
Both ends of the central rotating shaft protrude from the opening of the casing, and both ends of the protruding central rotating shaft are supported by bearing members present in a bearing portion in a bearing case provided so as to close the opening,
A lubricating oil supply means is connected to the bearing portions at both ends to supply lubricating oil to the bearing portions,
The present invention relates to a pulverizer for producing toner, characterized in that the lubricating oil supplying means includes an oil circulating chamber .
The present invention also relates to a method for producing a coloring agent, comprising the steps of: melt-kneading a mixture containing a binder resin and a colorant;
A step of cooling the obtained kneaded product;
a step of coarsely pulverizing the cooled product after cooling; and a step of finely pulverizing the obtained coarsely pulverized product by a fine pulverizing means.
A method for producing a toner comprising the steps of:
The present invention also relates to a method for producing a toner, characterized in that the fine pulverizing means is a pulverizer for producing a toner having the above-mentioned configuration.

According to the present invention, the rotor of a mechanical grinder can be operated stably at high speed for a long period of time.

FIG. 2 is a schematic diagram of a mechanical pulverizer used in the present invention. FIG. 2 is a schematic view of the inside of a bearing case of a mechanical crusher used in the present invention. FIG. 2 is a schematic view of the inside of a bearing case of a mechanical crusher used in the present invention. FIG. 2 is a schematic view of the inside of a bearing case of a mechanical crusher used in the present invention.

In the present invention, the expressions "xx or more and xx or less" or "xx to xx" that express a numerical range refer to a numerical range including the lower and upper limit endpoints, unless otherwise specified.

The present invention provides a pulverizer for producing toner, the pulverizer including a stator having a plurality of convex portions and concave portions on an inner peripheral surface thereof, and a rotor attached to a central rotating shaft and having a plurality of convex portions and concave portions on an outer peripheral surface thereof, the stator being disposed within a casing having a powder inlet and a powder outlet,
The stator contains the rotor, and the rotor is disposed so that a surface of the stator and a surface of the rotor face each other with a predetermined gap therebetween;
Both ends of the central rotating shaft protrude from the opening of the casing, and both ends of the protruding central rotating shaft are supported by bearing members present in a bearing portion in a bearing case provided so as to close the opening,
The present invention relates to a pulverizer for producing toner, characterized in that a lubricating oil supplying means for supplying lubricating oil to the bearings at both ends in a circulating manner is connected to the bearings.

According to the inventors' research, the above manufacturing method can provide a toner particle crushing device that can maintain the lubrication required for the bearings when crushing toner particles at high peripheral speeds, and does not impair toner productivity.

When a predetermined amount of coarsely pulverized material (material to be pulverized) is fed into the powder supply port 101 of the mechanical fine grinding machine shown in FIG. 1, the coarsely pulverized material is introduced into the grinding chamber, which is the gap between the rotor 103 and the stator 104. The material is then instantaneously pulverized by the impact generated between the rotor, which rotates at high speed in the grinding chamber and the stator, which also has many grooves on its surface. The material is then discharged through the powder discharge port 106.

Normally, the bearings 108-3 on the powder discharge side of a mechanical crusher are lubricated with grease. The finely ground product is sucked in from the powder discharge port 106 by a blower (not shown) and collected by a cyclone (not shown). The rear chamber 105 on the crushed discharge side is pulled with high pressure by the blower, so it is in a high negative pressure state. For this reason, if the bearings on the discharge side were oil lubricated, there would be a risk that the oil would be drawn into the rear chamber 105 of the crusher due to its high permeability, and that the oil would be mixed into the device, and so it could not be used until now. On the other hand, for the powder input side, the pressure loss caused by the rotor 103 works to significantly reduce the negative pressure inside the device, so the oil circulation system can be used.

Lubrication is a major factor in determining the performance of bearings. The role of lubrication is to lubricate each part of the bearing and reduce friction and wear.
・Removes heat generated inside the bearing due to friction and other causes,
・By constantly forming an appropriate oil film on the rolling contact surface of the bearing, the fatigue life of the bearing is extended.
・Anti-rust and dust-proofing of bearings are some of the functions that are important when rotating at high speeds, but the function of removing heat is also important.

The rotational speed of a bearing is limited by the temperature rise caused by frictional heat inside the bearing, and if it reaches a certain speed, the bearing will seize and will no longer be able to continue operating. Seizure occurs when the bearing heats up and becomes unable to rotate.

The allowable rotational speed of a bearing is the allowable value of the rotational speed at which it can continue to operate without generating heat that would lead to seizure. This allowable rotational speed varies depending on the type, dimensions, and tolerances of the bearing, the lubrication method, the quality and amount of lubricant, the shape and material of the cage, the load conditions, etc.

As the rotational speed of the bearing increases, the frictional heat generated inside the bearing causes the temperature of the bearing to rise, and once a certain limit is exceeded, the performance of the lubricant deteriorates significantly, causing abnormal temperature rise and seizure. The causes of seizure include:
・Poor heat dissipation for heat generated by bearings
- Insufficient lubrication or inappropriate lubricant may be the cause.

In the present invention, even though the mechanical crusher has the above configuration, the bearing on the discharge side is oil lubricated to realize high-speed rotation of the rotor 103. Figure 2 shows the bearing mechanism on the discharge side of the present invention. In the present invention, oil is sprayed by a jet nozzle (not shown) to provide a sufficient amount of oil to the bearing 108. The jet pressure is preferably 0.15 MPa or more and 0.60 MPa or less to satisfy the high-speed rotation range required in the present invention with the crusher specifications of this invention. In addition, oil is discharged from the oil circulation chamber (lubricating oil supply means) 111, and forced circulation oil supply is performed by a circulation tank and a pump (not shown). The oil circulation chamber 111 is installed between the second seal member 113 and the third seal member 114. It is preferable for the present invention that the circulating oil is cooled by a cooling means to maintain an appropriate temperature. In addition, in the present invention, a space 115 is provided between the first seal member 112 and the second seal member 113, and this space is connected to the atmosphere outside the bearing case by an atmosphere communication pipe 116. By doing this, even if the sealing ability of the first seal member weakens, the presence of space 115 communicating with the atmosphere prevents the negative pressure in the rear chamber 105 of the crusher from affecting the oil circulation chamber, eliminating the risk of oil being drawn into the crusher.

Oil seals are used as sealing materials, and oil is also applied to these oil seals, but the amount of oil is very small and disappears quickly during break-in after installation, so there is no need to worry about the oil getting mixed into the finely ground material.

As the bearing 108 of the present invention, a ball bearing or a cylindrical roller bearing is preferably used. By using the oil lubrication method of the present invention for these bearings, it is possible to rotate the rotor of the mechanical crusher stably at high speed for a long period of time.

In addition, in the present invention, the safety against oil being mixed into the device is further increased by having a pipe (118 in FIG. 3) extending downward from the space between the first seal member 112 and the second seal member 113 to the outside of the bearing case. With this configuration, even if the sealing ability of the seal member is reduced, the risk of space 115 becoming negative pressure can be further prevented by having two pipes that communicate with the atmosphere, one above and one below. Furthermore, even if lubricating oil passes through the second seal member and enters space 115, the oil is discharged outside the bearing case by the oil discharge pipe 118 installed facing downward, further eliminating the risk of oil being mixed into the crusher.

In addition, the present invention further enhances safety against lubricating oil getting into the grinding device by providing a means (117 in FIG. 4) for detecting the air pressure in the space between the first sealing member and the second sealing member. The air pressure detector tube 117 makes it possible to check the air pressure in the space 115, so the device can be stopped when it is confirmed that negative pressure has been reached.

Furthermore, it is possible to provide a separate means for sending airflow when negative pressure is detected, and to use this means to control the direction of releasing the negative pressure in space 115. Using such a means further increases the safety of the device against oil contamination.

Next, we will explain the procedure for producing toner particles using the manufacturing method of the present invention.

First, in the raw material mixing process, at least the binder resin and colorant are weighed out in predetermined amounts as toner internal additives, and then mixed. If necessary, a release agent that suppresses the occurrence of hot offset during heat fixing of the toner, a dispersant that disperses the release agent, a charge control agent, etc. may be mixed. Examples of mixing devices include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauta mixer.

The toner raw materials blended and mixed as described above are then melted and kneaded to melt the resins and disperse the colorants therein. In the melt-kneading process, for example, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. In recent years, single-screw or twin-screw extruders have become mainstream due to their advantages such as continuous production, and for example, a KTK twin-screw extruder manufactured by Kobe Steel, Ltd., a TEM twin-screw extruder manufactured by Toshiba Machine Co., Ltd., a twin-screw extruder manufactured by KCK Corporation, and a Co-Kneader manufactured by Buss Co., Ltd. are commonly used. Furthermore, the colored resin composition obtained by melt-kneading the toner raw materials is rolled with a twin roll or the like after melt-kneading, and cooled through a cooling process in which it is cooled with water or the like.

The cooled colored resin composition obtained above is coarsely pulverized to the desired particle size in the coarse pulverization process. In the coarse pulverization process, a pulverizer such as a crusher, hammer mill, or feather mill is usually used, but in the toner manufacturing method of the present invention, the particle size of the coarsely pulverized product supplied to the fine pulverization process is preferably 20 μm or more and 300 μm or less, and more preferably 20 μm or more and 200 μm or less.

If the particle size of the coarsely pulverized product supplied to the fine pulverization process exceeds 300 μm, there may be no productivity improvement effect for fine particle production. This is because if the particle size of the coarsely pulverized product is too large, the load applied locally to the fine pulverization device becomes too large, and even if the trajectory of the coarsely pulverized product within the device is changed as in the present invention, there may be a risk of fusion. On the other hand, if the particle size of the coarsely pulverized product is less than 20 μm, there is little impact on the fine pulverization process, but stable production in the coarse pulverization process becomes difficult, which is undesirable for toner production.

The coarse grinding machine used in the coarse grinding step in the toner manufacturing method of the present invention has two or more grinding zones equipped with a rotor consisting of a rotor with irregularities attached to at least the central rotating shaft for secondary grinding via a plurality of rotating hammers arranged on the same axis for primary grinding and a baffle plate for controlling the powder flow, and a stator with irregularities arranged around the rotor (rotor) with a fixed distance from the rotor surface, and the grinding zones are contained within one unit. It is more preferable to use a coarse grinding machine operated at the same rotation speed by the same power source. When using this coarse grinding machine, the desired coarse grinding particle size can be obtained by changing the rotation speed, making it suitable for controlling the coarse grinding particle size.

Next, we will explain the raw materials of the toner particles used in the present invention, which contain at least the binder resin and colorant.

<Binder resin>
As the binder resin used in the toner used in electrophotography, a general resin can be used. For example, polyester resin, styrene-acrylic acid copolymer, polyolefin resin, vinyl resin, fluororesin, phenol resin, silicone resin, epoxy resin, etc. Among these, from the viewpoint of improving low-temperature fixing property, amorphous polyester resin is used, and from the viewpoint of achieving both low-temperature fixing property and hot offset resistance, it is known to use a low-molecular-weight polyester and a high-molecular-weight polyester in combination. In addition, from the viewpoint of further improving low-temperature fixing property and blocking resistance during storage, a crystalline polyester may be used as a plasticizer.

<Coloring Agent>
Colorants that can be contained in the toner include the following.

The colorant may be a known organic pigment or oil-based dye, carbon black, or a magnetic material.

Cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds.

Magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.

Yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

Black colorants include carbon black, magnetic materials, or those toned to black using the above-mentioned yellow colorants, magenta colorants, and cyan colorants.

The colorants can be used alone or in combination of two or more.

<Release Agent>
If necessary, a release agent for suppressing the occurrence of hot offset during the heat fixing of the toner may be used. Typical examples of the release agent include low molecular weight polyolefins, silicone wax, fatty acid amides, ester waxes, carnauba wax, and hydrocarbon waxes.

[Method for measuring particle size distribution of finely pulverized particles]
The particle size distribution of the finely ground product was measured as follows.

The measuring device used is a precision particle size distribution measuring device using the pore electrical resistance method, "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), equipped with a 50 μm aperture tube. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.). The measurement is performed using an effective measurement channel count of 25,000 channels.

The electrolyte solution used for the measurements is one in which special grade sodium chloride is dissolved in ion-exchanged water to give a concentration of approximately 1% by mass, for example "ISOTON II" (manufactured by Beckman Coulter).

Before performing measurements and analysis, configure the dedicated software as follows:

In the "Change Standard Measurement Method (SOM)" screen of the dedicated software, set the total count number in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particles 10.0 μm" (manufactured by Beckman Coulter).

Press the "Threshold/Noise Level Measurement Button" to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement."

In the dedicated software's "Pulse to particle size conversion setting" screen, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 1 μm to 30 μm.

The specific measurement method is as follows.
(1) Pour about 200 mL of the electrolyte solution into a 250 mL round-bottom glass beaker made exclusively for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, remove dirt and air bubbles from inside the aperture tube using the "aperture flush" function of the dedicated software.
(2) About 30 mL of the aqueous electrolyte solution is placed in a 100 mL flat-bottom glass beaker, and about 0.3 mL of a dilution obtained by diluting "Contaminon N" (a 10% aqueous solution of a neutral detergent for cleaning precision measuring instruments, pH 7, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) about 3 times by mass with ion-exchanged water is added thereto as a dispersant.
(3) Prepare an ultrasonic disperser "Ultrasonic Dispersion System Tetorara 150" (manufactured by Nikkaki Bios Co., Ltd.) that has two built-in oscillators with an oscillation frequency of 50 kHz and a phase shift of 180 degrees and an electrical output of 120 W. Place about 3.3 L of ion-exchanged water in the water tank of the ultrasonic disperser, and add about 2 mL of Contaminon N to this water tank.
(4) The beaker from (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid surface of the electrolyte solution in the beaker is maximized.
(5) In a state where the electrolyte solution in the beaker in (4) is irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolyte solution and dispersed. Then, ultrasonic dispersion treatment is continued for another 60 seconds. During ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted so as to be 10°C or higher and 40°C or lower.
(6) The electrolytic solution (5) in which the toner is dispersed is dropped using a pipette into the round-bottom beaker (1) placed in the sample stand, and the measurement concentration is adjusted to about 5%. Then, the measurement is continued until the number of particles measured reaches 50,000.
(7) The measurement data is analyzed using the dedicated software that comes with the device, and the weight-average particle size (D4) is calculated. Note that when the dedicated software is set to Graph/Volume %, the "Average diameter" on the "Analysis/Volume Statistics (Arithmetic Mean)" screen is the weight-average particle size (D4).

[Method for measuring particle size distribution of coarsely ground particles]
The particle size distribution of the coarsely ground material was measured using a particle size distribution measuring device LA-950V2 (manufactured by Horiba, Ltd.). This device uses a laser scattering method to measure particle sizes from 0.01 μm to 3000 μm. The particle size of the coarsely ground material was measured by wet measurement using this device. For the wet measurement method, the coarsely ground material was mixed with an aqueous medium, and ultrasonically dispersed using "Contaminon N" as a dispersant in the same manner as with the Coulter Counter, and the mixture was introduced into the device.

The measurements were performed using a refractive index of 1.53 for the sample (coarsely ground material) and 1.33 for the dispersion medium.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

<Production Example of Polyester Resin L>
Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane: 72.0 parts by mass (0.20 moles; 100.0 mol% based on the total number of moles of polyhydric alcohol)
・Terephthalic acid:
28.0 parts by mass (0.17 moles; 100.0 mol% based on the total number of moles of polyvalent carboxylic acids)
Tin 2-ethylhexanoate (esterification catalyst): 0.5 parts by mass The above materials were weighed and placed in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen inlet tube, and a thermocouple. The atmosphere in the flask was then replaced with nitrogen gas, and the temperature was gradually raised with stirring, and the mixture was allowed to react for 4 hours at 200°C with stirring.

The pressure inside the reaction vessel was then reduced to 8.3 kPa and maintained for 1 hour, after which the vessel was cooled to 180° C. and returned to atmospheric pressure.
・Trimellitic anhydride:
3 parts by mass (0.01 mole; 4.0 mol% based on the total number of moles of polycarboxylic acids)
tert-Butylcatechol (polymerization inhibitor): 0.1 part by mass Thereafter, the above materials were added, the pressure in the reaction tank was reduced to 8.3 kPa, and the reaction was carried out for 1 hour while maintaining the temperature at 180° C. After it was confirmed that the softening point measured in accordance with ASTM D36-86 reached 90° C., the temperature was reduced to stop the reaction, and an amorphous polyester resin L, which was a binder resin, was obtained.

<Production Example of Polyester Resin H>
Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane: 72.3 parts by mass (0.20 moles; 100.0 mol% based on the total number of moles of polyhydric alcohol)
・Terephthalic acid:
18.3 parts by mass (0.11 moles; 65.0 mol% based on the total number of moles of polyvalent carboxylic acids)
Fumaric acid:
2.9 parts by mass (0.03 moles; 15.0 mol% based on the total number of moles of polyvalent carboxylic acids)
Tin 2-ethylhexanoate (esterification catalyst): 0.5 parts by mass The above materials were weighed and placed in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen inlet tube, and a thermocouple. The atmosphere in the flask was then replaced with nitrogen gas, and the temperature was gradually raised with stirring, and the mixture was allowed to react for 2 hours at 200°C while stirring.

The pressure in the reaction vessel was then reduced to 8.3 kPa and maintained for 1 hour, after which it was cooled to 180 and returned to atmospheric pressure.
・Trimellitic anhydride:
6.5 parts by mass (0.03 moles; 20.0 mol% based on the total number of moles of polyvalent carboxylic acids)
tert-Butylcatechol (polymerization inhibitor): 0.1 part by mass Thereafter, the above materials were added, the pressure in the reaction tank was reduced to 8.3 kPa, and the reaction was carried out for 15 hours while maintaining the temperature at 160° C. After it was confirmed that the softening point measured in accordance with ASTM D36-86 reached 137° C., the temperature was reduced to stop the reaction, and an amorphous polyester resin H, which was a binder resin, was obtained.

<Crystalline Polyester Resin>
1,6-Hexanediol:
34.5 parts by mass (0.29 moles; 100.0 mol% based on the total number of moles of polyhydric alcohol)
・Dodecanedioic acid:
65.5 parts by mass (0.28 moles; 100.0 mol% based on the total number of moles of polycarboxylic acids)
The above materials were weighed and placed in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen inlet tube, and a thermocouple. After replacing the atmosphere in the flask with nitrogen gas, the temperature was gradually raised with stirring, and the reaction was carried out for 3 hours at 140° C. with stirring.

Next, the above materials were added, the pressure in the reaction vessel was reduced to 8.3 kPa, and the reaction was carried out for 4 hours while maintaining the temperature at 200°C.

The pressure in the reaction vessel was gradually released to return to normal pressure, and then 7.0 mol % of one or more aliphatic compounds selected from the group consisting of aliphatic monocarboxylic acids and aliphatic monoalcohols was added to 100.0 mol % of the raw material monomer, and the mixture was reacted at 200°C for 2 hours under normal pressure.

After that, the pressure in the reaction tank was reduced again to 5 kPa or less, and the reaction was carried out at 200°C for 3 hours to obtain a crystalline polyester resin.

<Toner Production Example>
Amorphous polyester resin L 75 parts by mass Amorphous polyester resin H 25 parts by mass Crystalline polyester resin 3 parts by mass Fischer-Tropsch wax (hydrocarbon wax, maximum endothermic peak temperature 90 ° C.) 5 parts by mass C.I. Pigment Blue 15:3 7 parts by mass The above materials were mixed using a Henschel mixer (FM-300L) at a rotation speed of 1200 rpm for a rotation time of 5 min, and then kneaded with a twin-screw kneader (PCM-92 type, manufactured by Ikegai Corporation). The barrel temperature during kneading was set so that the outlet temperature of the kneaded product was 120 ° C. The outlet temperature of the kneaded product was directly measured using a handheld thermometer HA-200E manufactured by Anritsu Keiki Co., Ltd. The kneaded product obtained was then cooled.

Then, coarsely ground material A with a particle size of 60 μm was obtained using a coarse grinding machine.

Example 1
In this embodiment, the rotor 103 of the pulverizer shown in Fig. 1 had a diameter of 800 mm. The minimum gap with the stator 104 was set to 1.0 mm, and the temperature of the air introduced into the mechanical fine pulverizer was -20°C. The rotor 103 used was equipped with a refrigerant flow path for cooling inside, as described in Japanese Patent No. 5094088, with the refrigerant temperature: -10°C and flow rate: 10 ^m3 /min. The suction blower specifications were 55 kW, ³⁵ Nm3/min, and -31 kPa.

As the bearing 108-3 on the discharge side shown in FIG. 2, a cylindrical roller bearing NU217EA from the ULTAGE series manufactured by NTN Corporation was used. This ULTAGE series uses a resin cage to increase speed and load capacity. In this embodiment, oil is sprayed onto this bearing 108-3 using a jet nozzle (not shown). The jet pressure was set to 0.55 MPa. The sprayed oil is discharged from a discharge pipe (not shown) to the outside of the oil circulation chamber 111. The discharged oil returns to the tank, and immediately after being released from the tank again, it is cooled through a heat exchanger and supplied to the bearing section. The oil circulation flow rate was set to 0.85 L/min. The amount of oil supplied (circulation amount) varies depending on the bearing diameter, bearing load, rotation speed, etc., so the amount of oil described in this embodiment will naturally vary if the scale of the device changes. In general, the amount of oil required increases in proportion to the bearing diameter, load, and rotation speed.

In this embodiment, as shown in FIG. 2, a space 115 and an air communication pipe 116 are provided on the pulverizer side with respect to the oil circulation chamber 111. On the other hand, the powder inlet side is provided with two bearings as shown in FIG. 1, 108-1 being a four-point contact ball bearing and 108-2 being a cylindrical roller bearing. The bearings on the powder inlet side are also of the oil jet type circulation specification, as with the discharge outlet side. The oil supply amount is the same as that of the powder discharge side bearing 108-3. Also, the bearing part on the powder inlet side does not have the space 115 provided on the discharge side. This is because, as mentioned above, the negative pressure inside the pulverizer is weak on the powder inlet side, so there is almost no risk of oil being drawn into the pulverizer and mixed in. On the other hand, the negative pressure inside the device is strong on the discharge outlet side, so a space 115 and an air communication pipe 116 are provided to prevent oil from being drawn in.

The rotation speed of the rotor 103 was set as follows, and the supply rate of the coarsely pulverized material A from the powder inlet 101 was set to 150 kg/hr.
Condition 1: The peripheral speed of the conventional upper limit rotor 103 was set to 172 m/sec.
Condition 2: The peripheral speed of the high-speed rotor 103, which is faster than the conventional one, was set to 180 m/sec.
Condition 3: The peripheral speed of the high-speed rotor 103, which exceeds the conventional speed, was set to 193 m/sec.
Condition 4: The peripheral speed of the rotor 103, which rotates at a higher speed than in the past, was set to 205 m/sec.
Condition 5: The peripheral speed of the high-speed rotor 103, which exceeds the conventional speed, was set to 215 m/sec.

The static pressure at the powder inlet and outlet sides of the grinder and the blower air volume under each condition are shown in Table 1.

The unit was operated continuously for one hour under the above conditions, and the temperature of the area close to the bearings in the bearing case was measured to evaluate the temperature rise of the bearings. It was determined that the allowable temperature for the bearings was room temperature + 40°C or less, which was a safe operating level. Since the room temperature at the time of this evaluation was approximately 23°C, it could be determined that a temperature of 63°C or less meant that the bearings were designed to withstand high-speed rotation.

The evaluation results for this example are shown in Table 1. The temperature inside the circulating oil tank and the temperature after cooling of the circulating oil are also shown along with the bearing case temperature. The bearing temperature is lower than the lubricating oil temperature, but this is thought to be because the temperature inside the crusher is cooled by the cold air and the cooling of the rotor 103, and the bearing 108 is also cooled through the rotating shaft 107. Also, as evaluation results, Table 2 shows only the temperature of the bearing 108-3 on the discharge port side, but this is the pulley 110 side (the side where the load is applied) and the bearing temperature rise on the input port side also showed the same trend as the discharge port side, so only the discharge port side is shown as a representative. (The same applies to the following examples.)

In this example, the temperature rise was not a problem even under the most severe condition 5.

After operation was completed, the crusher was opened and the oil seal 112 was observed from the crusher side, but no oil was found to be leaking out.

The particle size of the ground material obtained under each of the conditions was as follows:
Condition 1: 5.0 μm
Condition 2: 4.7 μm
Condition 3: 4.3 μm
Condition 4: 4.0 μm
Condition 5: 3.8 μm

Example 2
The oil jet pressure was 0.30 MPa. The oil circulation flow rate was 0.70 L/min. The other conditions were the same as in Example 1, and the same evaluation was performed.

The static pressure and blower air volume inside the crusher are shown in Table 1, and the evaluation results of the bearing temperature are shown in Table 2. The oil supply and circulation amounts were reduced compared to Example 1, so the bearing temperature rose, but the temperature was still at a level that was not problematic.

After the operation was completed, the crusher was opened and the oil seal 112 was observed from the crusher side, but no oil was seen to be blowing out. The crushed particle size was also the same as in Example 1.

Example 3
The oil jet pressure was 0.15 MPa. The oil circulation flow rate was 0.60 L/min. The other conditions were the same as in Example 1, and the same evaluation was performed.

The static pressure and blower air volume inside the crusher are shown in Table 1, and the evaluation results of the bearing temperature are shown in Table 2. The oil supply and circulation amounts were reduced compared to Example 2, so the bearing temperature rose, but the temperature was still at a level that was not problematic.

After the operation was completed, the crusher was opened and the oil seal 112 was observed from the crusher side, but no oil was seen to be blowing out. The crushed particle size was also the same as in Example 1.

Example 4
In this example, the suction blower had specifications of 75 kW, 45 Nm ³ /min, and -31 kPa. The other conditions were the same as in Example 1, and the same evaluation was performed.

Table 1 shows the static pressure and blower air volume inside the pulverizer, and Table 2 shows the evaluation results of the bearing temperature. Compared to Example 1, the bearing temperature was slightly lower under all conditions. The air volume increased due to an increase in the blower specifications. The crushed particle size was also coarser by about 0.1 μm under all conditions compared to Example 1. This is thought to be because the increased air volume shortened the time the particles stayed in the device, resulting in a slightly coarser crushed particle size. The decrease in bearing temperature is thought to be due to the fact that the crushed particle size worsened, reducing the amount of work the device was required to do, and the increased air volume caused the temperature inside the device to drop slightly.

The evaluation was also performed under conditions where the blower suction was increased and negative pressure was strong on the pulverizer outlet side, but by using the configuration of the present invention, no oil was observed spraying out into the device.

Example 5
In this embodiment, a normal cylindrical roller bearing NU217E that does not use a resin cage was used as the bearing 108-3 on the discharge side. The other conditions were the same as in Example 1, and the same evaluation was performed.

The static pressure inside the grinder and the blower air volume are shown in Table 1, and the evaluation results are shown in Table 2. The bearing temperature increased compared to Example 1, but was still at a level that did not pose a problem.

After the operation was completed, the crusher was opened and the oil seal 112 was observed from the crusher side, but no oil was seen to be blowing out. The crushed particle size was also the same as in Example 1.

Example 6
In this embodiment, a rotor 103 that does not have a cooling medium passage therein is used. The other conditions are the same as in the first embodiment, and a similar evaluation is performed.

The static pressure and blower air volume inside the crusher are shown in Table 1, and the evaluation results of the bearing temperature are shown in Table 2. The bearing temperature rose compared to Example 1. Under conditions 4 and 5, the bearing temperature rose to room temperature +40°C or more, which was an insufficient level for use in long-run production. Under conditions 1 to 3, the temperature was below room temperature +40°C, so it can be determined that they are suitable for use in production. The reason the bearing temperature rose compared to Example 1 is thought to be because the cooling effect through the rotating shaft 107 was weakened by eliminating cooling of the rotor 103.

After operation was completed, the crusher was opened and the oil seal 112 was observed from the crusher side, but no oil was found to be leaking out.

Comparative Example 1
In this example, the bearing 108-3 on the powder outlet side was lubricated with grease. The other conditions were the same as in Example 1, and the same evaluation was performed.

The static pressure inside the grinder and the blower air volume are shown in Table 1, and the evaluation results of the bearing temperature are shown in Table 2.

Under condition 1, the temperature was not a problem, but under condition 2, the bearing temperature rose to 75°C, an insufficient level for long-run production use.

In addition, under condition 3, the device stopped operating about 30 minutes after it started. This was because the bearings had burned out.

Comparative Example 2
In this example, the bearing 108 on the powder outlet side is lubricated by oil-air lubrication. Since it is supplied by the oil-air method, a small amount of lubricating oil is continuously supplied at required intervals using compressed air. It consists of a fixed-volume piston-type distributor that discharges the lubricating oil supplied from an oil tank (not shown) in small amounts at a time, and a compressed air source that continuously supplies compressed air to the small amount of lubricating oil discharged by this distributor. The discharge amount of the piston-type distributor can be adjusted by the length of the fixed-volume nipple, etc., but is generally in the range of 0.01 to 1.5 ^cm3 . In this example, a piston-type distributor with a discharge amount of 1.5 ^cm3 was used. The amount of oil supplied to the bearing was about 0.05 mL/min.

Other conditions were the same as in Example 1, and a similar evaluation was performed.

The static pressure inside the grinder and the blower air volume are shown in Table 1, and the evaluation results of the bearing temperature are shown in Table 2.

Under condition 1, the temperature was not a problem, but under condition 2, the temperature rose to 65°C. Although the temperature was lower than in comparative example 1, it was more than 40°C above room temperature, which was not at a level acceptable for the present invention. Under condition 3, the temperature rose to 80°C, which was an insufficient level for use in long-run production.

In addition, under condition 4, the device stopped about 30 minutes after starting operation. This was because the bearings had burned out. In this example, the amount of oil supplied was less than in examples 1 to 3, so the bearings could not keep up with the temperature rise in the higher-speed rotation range than in the past, which is thought to have caused the bearings to burn out.

Comparative Example 3
In this example, as in Comparative Example 2, the discharge amount of the piston type distributor using the oil-air lubrication method was 0.5 cm ³ , and the amount of oil applied to the bearings was approximately 0.02 mL/min.

Other conditions were the same as in Comparative Example 2, and a similar evaluation was performed.

The static pressure inside the grinder and the blower air volume are shown in Table 1, and the evaluation results of the bearing temperature are shown in Table 2.

Under condition 1, the temperature was not a problem, but under condition 2, the bearing temperature rose to 73.5°C, an insufficient level for long-run production use.

In addition, under condition 3, the device stopped operating about 40 minutes after it started. This was because the bearings had burned out.

[Reference Example 1]
In this example, as shown in Fig. 3, a pipe was provided downward from space 115 as oil discharge pipe 118. The other configuration was the same as in Example 4. The specifications of the suction blower used were 75 kW, 45 ^Nm3 /min, -31 kPa, and the peripheral speed of rotor 103 was 215 m/sec.

The static pressure on the input side was 2.5 kPa, the static pressure on the discharge side was 34 kPa, and the air volume was 30 m ³ /min. The supply rate of the coarsely pulverized material A from the powder input port 101 was set to 150 kg/hr, and continuous operation was performed for 1 hour.

In this example, although it was an irregular procedure, 10 ml of oil was placed in space 115 before starting operation and an evaluation was performed.

After the operation was completed, the crusher was opened and the oil seal 112 was observed from the crusher side. No oil was found to be blowing out. This is because the oil was discharged outside the bearing case through the oil discharge pipe 118, and the space 115 did not become negative pressure due to the air communication pipe 116.

[Reference Example 2]
In this example, as shown in Fig. 4, an air pressure detector tube 117 is provided from space 115. When the air pressure detector tube detects that space 115 is under negative pressure, feedback control is performed to bring the device to an emergency stop. Other conditions were the same as in Example 4. The suction blower specifications were 75 kW, 45 ^Nm3 /min, -31 kPa, and the peripheral speed of rotor 103 was 215 m/sec.

The static pressure on the input side was 2.6 kPa, the static pressure on the discharge side was 33.8 kPa, and the air volume was 30 m ³ /min.

In this example, although it was an irregular procedure, an oil seal 112 was used in which the part that slides against the rotating shaft 107 was already worn down.

In this example, the operation was carried out without adding any coarsely ground material.

Shortly after starting operation, the air pressure detector 117 detected negative pressure and the device stopped. When the crusher was opened and the oil seal 112 was observed from the crusher side, no oil was seen to be leaking.

101: Grinding supply port, 103: Rotor, 104: Stator, 105: Rear chamber, 106: Powder discharge port, 107: Rotating shaft, 108: Bearing, 109: Bearing case, 110: Pulley, 111: Oil circulation chamber (lubricating oil supply means), 112: First seal member, 113: Second seal member, 114: Third seal member, 115: Space, 116: Atmospheric communication pipe, 117: Air pressure detection tube, 118: Oil discharge pipe

Claims (7)

A casing having a powder inlet and a powder outlet is provided therein.
A stator having a plurality of protrusions and recesses on an inner circumferential surface thereof;
a rotor attached to a central rotating shaft and having a plurality of protrusions and recesses on an outer circumferential surface;
A pulverizer for producing toner, comprising:
The stator contains the rotor, and the rotor is disposed so that a surface of the stator and a surface of the rotor face each other with a predetermined gap therebetween;
Both ends of the central rotating shaft protrude from the opening of the casing, and both ends of the protruding central rotating shaft are supported by bearing members present in a bearing portion in a bearing case provided so as to close the opening,
A lubricating oil supply means is connected to the bearings at both ends to supply lubricating oil to the bearings in a circulating manner,
The pulverizer for producing toner, wherein the lubricating oil supplying means includes an oil circulating chamber . A first seal member is provided in the bearing case at each end of the bearing, the first seal member being disposed on the rotor side, a second seal member being disposed farther away from the rotor than the first seal member, and a third seal member being disposed farther away from the rotor than the second seal member.
the bearing portion is provided between the second seal member and the third seal member,
2. The pulverizer for producing toner according to claim 1, wherein an atmosphere communication pipe is connected to a space between said first seal member and said second seal member. The toner production pulverizer according to claim 1 or 2, wherein the bearing is a ball bearing or a roller bearing. The toner production pulverizer according to any one of claims 1 to 3, further comprising a tube extending downward from the space between the first seal member and the second seal member to the outside of the bearing case. The toner production pulverizer according to any one of claims 1 to 4, further comprising a means for detecting the air pressure in the space between the first seal member and the second seal member. The toner production pulverizer according to claim 5, further comprising a means for controlling the pulverizer in a direction to release the negative pressure in the space when the means for detecting the air pressure in the space detects a negative pressure. A step of melt-kneading a mixture containing a binder resin and a colorant;
A step of cooling the obtained kneaded product;
a step of coarsely pulverizing the cooled product after cooling; and a step of finely pulverizing the obtained coarsely pulverized product by a fine pulverizing means.
A method for producing a toner comprising the steps of:
A method for producing a toner, comprising using a pulverizer for producing a toner according to any one of claims 1 to 6 as said fine pulverizing means.

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