JP7618396B2 - Toner manufacturing method - Google Patents

Description

The present invention relates to a method for producing toner used in electrophotography, electrostatic recording, electrostatic printing, and toner jet methods.

In recent years, full-color electrophotographic copiers have become widespread and are beginning to be applied to the printing market, where there is a demand for high-quality prints at high speed while supporting a wide range of media (paper types).
As a specific measure for achieving high image quality, in order to improve dot reproducibility, there is a demand for a toner having a small toner particle size and a uniform particle size distribution that does not contain coarse particles or fine particles.
One method for dry toner production is the following. First, a binder resin for fixing to a transfer material, various colorants for imparting color as a toner, and additives such as a release agent and a flowability agent are added and mixed in a dry state. Next, the mixture is melted and mixed in a general-purpose kneading device such as a roll mill or an extruder, cooled and solidified, and then the kneaded mixture is pulverized in various grinding devices, and the resulting coarsely ground product is introduced into various air classifiers for classification to obtain a classified product with a particle size required for a toner. Furthermore, a flowability agent, a lubricant, and the like are externally added as necessary, and the mixture is dry mixed to obtain a toner for use in image formation.
One example of a device for finely pulverizing a kneaded material is a mechanical pulverizer that pulverizes the material between a rotor that rotates at high speed and a stator that is arranged around the rotor (Patent Document 1). In this method, the material to be pulverized moves at high speed between the rotor and the stator due to the rotor rotating at high speed, and is pulverized by the collisions that occur at that time.
It is possible to obtain toner having a desired particle size by controlling the rotation speed of the rotor. However, there is a limit to the rotation speed of the rotor in the grinding machine, and therefore there is also a limit to the achievable toner particle size.
As a toner micronization device different from a mechanical pulverizer, there is an airflow pulverizer, which uses high-pressure air to move the material to be pulverized at high speed and pulverizes the material by the collision energy generated at that time (Patent Document 2). This method makes it possible to impart higher collision energy to the material to be pulverized, but it is known that the particle size distribution of the obtained toner particles is broader than that of a mechanical pulverizer.

JP 2011-237816 A JP 2006-051496 A

As mentioned above, in order to improve the image quality of printed matter, there is a demand for toner particles with small diameters and a uniform particle size distribution that does not contain coarse or fine particles. The sharper the particle size distribution in the toner micronization process, the smaller the amount of fine and coarse powder that needs to be removed in the subsequent classification process, which is preferable from the standpoint of productivity. The object of the present invention is to provide a method for producing toner particles with small particle diameters and a sharp particle size distribution in the toner micronization process.

In order to solve the above problems of the conventional technology, the present inventors conducted research and discovered that the method of supplying raw materials in a mechanical grinder is related to the particle size and particle size distribution of the obtained toner particles, and thus arrived at the present invention.
That is, the present invention provides a method for producing a toner, comprising a step of finely pulverizing a material to be pulverized, the material containing a binder resin and a colorant, by a pulverizing means,
The crushing means is
A powder supply mechanism for supplying the material to be pulverized;
a stator having a plurality of protrusions and recesses on an inner circumferential surface;
a rotor attached to a central rotating shaft and having a plurality of protrusions and recesses on an outer circumferential surface;
A powder discharge port for discharging the finely pulverized material;
having
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;
The convex portions and concave portions present on the inner peripheral surface of the stator and the outer peripheral surface of the rotor are formed along the axial direction of the central rotation shaft,
The protruding portion of the stator and the protruding portion of the rotor face each other with a gap of 0.8 mm or more and 1.4 mm or less between them,
The material to be pulverized is accelerated and sprayed by the powder supply mechanism, and is supplied from a supply port so as to collide directly with the outer circumferential surface of the rotor. In a pulverization region formed by a gap between the stator and the rotor, the material is pulverized by the rotation of the rotor.
When the rotor is divided into four equal parts along the central rotation axis, and each of the four equal parts is designated as a first region to a fourth region along the flow of the material to be crushed,
(i) a position where the material to be pulverized is accelerated and jetted by the powder supply mechanism and collides with the rotor is a first region;
(ii) the powder discharge port is provided downstream of the flow of the material to be ground ;
The accelerated air velocity when the material to be pulverized is accelerated and sprayed is 10 m/sec or more and 50 m/sec or less when passing through the supply port.
The present invention relates to a method for producing a toner.

The present invention makes it possible to provide toner with a small particle size while maintaining high productivity.

FIG. 1 is a diagram of a typical grinding device. FIG. 2 is a diagram of a grinding device used in the present invention. FIG. 2 is a diagram illustrating a raw material supply position in the grinding device used in the present invention. 4A and 4B are diagrams illustrating the uneven shapes of a stator and a rotor. FIG. 1 is a diagram of an interlocking tooth grinding device.

The present invention differs from conventional mechanical grinding devices in that it uses high-pressure air to accelerate and inject the material to be ground into the grinding chamber, where it collides directly with the rotor that rotates at high speed. The following is an overview of the mechanical grinder used to implement the present invention.

- Apparatus Figure 1 shows a schematic cross-sectional view of a conventional general mechanical grinding apparatus. The illustrated figure shows a horizontal type apparatus, but it may be a vertical type apparatus. It is composed of a supply port 101 for supplying the material to be ground and cold air, a rotor 103 having a number of irregularities on its outer circumferential surface attached to a central rotating shaft 107, a stator 104 having a number of irregularities on its inner circumferential surface arranged at a certain interval on the outer circumferential surface of the rotor 103, a cold water supply port 109 for circulating cooling water around the outer circumferential surface of the stator, a cold water discharge port 110, and a discharge port 106 for discharging the powder (finely ground material) and cold air after processing.

In the mechanical grinding machine configured as above, when a predetermined amount of powder raw material is fed into the supply port 101, the raw material is introduced into the grinding processing chamber via the front chamber 102. In the grinding processing chamber, the rotor 103, which has many irregularities on its surface, rotates at high speed, and the stator 104, which also has many irregularities on its surface. The rotor 103 and the stator 104 are instantly ground by the impact between them, which generates many ultra-high speed vortexes behind them, and the high-frequency pressure vibrations generated by them. The raw material is then discharged through the discharge port 106. The air carrying the particles passes through the grinding processing chamber and is discharged from the discharge port 106. In order to collect the powder after processing, a cyclone connected to the discharge port 106 using piping or the like can be used to separate the powder in the airflow.

Examples of such mechanical grinding machines include the Innomizer (manufactured by Hosokawa Micron Corporation), Cryptoline (manufactured by Kawasaki Heavy Industries, Ltd.), Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.), and Tornado Mill (manufactured by Nikkiso Co., Ltd.). These can be used as is or with appropriate modifications.

Carbon steel such as S45C or chrome-molybdenum steel such as SCM material is often used as the base material for the rotors and stators in mechanical crushers. By coating the surface of these base materials with a chrome alloy and then carrying out a mechanical surface treatment, the surface hardness and wear resistance of the crushed surface are increased, resulting in rotors and stators with long life, enabling long runs.

In particular, coating the surface of a chromium alloy containing chromium carbide on the base material surface can be finished uniformly and smoothly by plating, reducing the coefficient of friction and improving wear resistance. After plating, polishing such as buffing or blasting such as shot blasting can be performed to smooth the surface roughness of the rotor and stator.

In the present invention, the method of feeding the material to be crushed is changed as described above, and the material is supplied directly to the rotor 103, which rotates at high speed, using compressed air from the material supply port 201, as shown on the right side of Figure 2. At this time, the material to be crushed is accelerated and ejected, colliding directly with the outer periphery of the rotor 103 and being crushed.

The left side of Figure 2 shows a schematic cross-sectional view taken along the D-D' plane in the right side of Figure 2. The multiple convex and concave portions on the surfaces of the rotor and stator are formed along the axial direction of the central rotation shaft of the rotor. In the present invention, fine grinding is carried out in the grinding region formed by the gap between the stator and rotor, and it is important that the material to be ground is supplied from the supply port so that it collides directly with the outer circumferential surface of the rotor. It is believed that this makes it possible to impart higher collision energy to the material to be ground.

The air speed when the compressed air is accelerated and sprayed also has a large effect on the particle size of the toner particles. The air speed must be between 10 m/sec and 50 m/sec when passing through the supply port. If the air speed is below 10 m/sec, the effect of reducing the particle size of the toner particles cannot be obtained. Furthermore, if the air speed exceeds 50 m/sec, excessive collision energy is imparted, and the particle size distribution of the toner particles becomes broad due to over-pulverization.

Figure 4 is a schematic diagram of the uneven shape present on the rotor and stator. The distance Db between the convex parts of the rotor and stator is preferably 0.8 mm to 1.4 mm, and more preferably 0.8 mm to 1.2 mm. The distance Da between the convex parts of the rotor and stator is preferably 1.0 mm to 1.5 mm. When Da and Db are in this range, the rotor rotates at high speed, generating a high-speed vortex between the rotor and the stator. This allows the material to be crushed to be efficiently repeatedly collided with the rotor and stator, allowing for further fine grinding. In addition, when the material to be crushed in the crushing chamber after the collision is finer to a certain particle size, it is quickly discharged from the raw material discharge port due to the influence of the air flow in the processing chamber. This makes it possible to suppress the broadening of the particle size distribution due to over-crushing.

In order to enhance the effect of the present invention, the angle at which the material to be pulverized is introduced by accelerated injection is also important. The material to be pulverized is supplied so as to face the direction of rotation of the rotor, and the angle θ between the direction of introduction of the material to be pulverized in the left diagram in FIG. 2 and the tangent direction at the raw material inlet in a plane perpendicular to the rotation axis of the rotor is preferably 20° or more and 80° or less, more preferably 30° or more and 70° or less. The smaller the value of θ, the higher the relative speed at the time of collision between the material to be pulverized and the rotor can be. However, when the collision speed exceeds a certain value, the material to be pulverized tends to be over-pulverized, and the particle size distribution of the resulting toner particles becomes broad. Also, when θ is large, the relative speed between the material to be pulverized and the rotor does not increase, and therefore toner particles of the desired particle size cannot be obtained. For the above reasons, θ is preferably in the above range.

As with the angle of the raw material supply port, the raw material supply position also affects the particle size of the resulting toner particles. That is, if the rotor is divided into four equal parts along the central rotation axis, and each of the four equal parts is designated as the first to fourth regions along the flow of the ground material, (i) the position where the ground material is accelerated and sprayed by the powder supply mechanism and collides with the rotor is the first region, and (ii) the powder discharge port must be provided within the region of the stator facing the fourth region. If this aspect is not met, the grounding in the grinding processing chamber after the airflow collision will not be sufficient, and toner particles of the desired particle size will not be obtained.

Figure 3 specifically explains the above embodiment, and the ratio Lj/Lr of the distance Lj from the end of the rotor on the supply port 101 side to the raw material supply port 201 to the total length Lr of the rotor in Figure 3 must be 0 or more and 0.25 or less, and is preferably 0 or more and 0.15 or less.

(Toner Manufacturing Procedure)
Next, a procedure for producing a toner using the production method and production apparatus of the present invention will be described.

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 then pulverized to the desired particle size in a pulverization process. In the pulverization process, the colored resin composition is first coarsely pulverized using a crusher, hammer mill, feather mill, or the like. It is then finely pulverized using the mechanical pulverizer of the present invention. In this way, the colored resin composition is pulverized stepwise to the desired toner particle size in the pulverization process.

(Toner raw materials)
Next, the raw materials of the toner, which contains at least the binder resin and the colorant used in the present invention, will be described.

<Binder resin>
As the binder resin used in the toner used in electrophotography, a general resin can be used, and examples thereof include polyester resin, styrene-acrylic acid copolymer, polyolefin resin, vinyl resin, fluororesin, phenol resin, silicone resin, and epoxy resin. 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.

Next, we will explain how to measure the characteristic values related to the present invention and the examples described below.

<Calculation of accelerated injection speed>
The speed of the accelerated jet of the material to be pulverized was calculated from the following formula 1. The volumetric flow rate used was a value obtained by measuring with a flow meter.
(Velocity) = (Volumetric flow rate) / (Effective cross-sectional area of the pipe) (Equation 1)

(Measurement of Toner Particle Size Distribution)
<Method of Measuring Weight Average Particle Size (D4) of Toner>
The weight average particle diameter (D4) of the toner is measured using a precision particle size distribution measuring device using a pore electrical resistance method equipped with a 50 μm aperture tube, “Coulter Counter Multisizer 3” (registered trademark, manufactured by Beckman Coulter, Inc.), and the accompanying dedicated software for setting measurement conditions and analyzing measurement data, “Beckman Coulter Multisizer 3 Version 3.51” (manufactured by Beckman Coulter, Inc.), with an effective measurement channel count of 25,000, and the measurement data is analyzed and calculated.

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 Particle 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 the aperture tube flush 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 or more and 30 μm or less.

The specific measurement method is as follows.
(1) Pour about 200 ml of the electrolyte solution into a 250 ml round-bottom glass beaker for use with 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 analysis software.
(2) Approximately 30 ml of the aqueous electrolyte solution is placed in a 100 ml flat-bottom glass beaker, and approximately 0.3 ml of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, having a pH of 7, manufactured by Wako Pure Chemical Industries, Ltd.) three times by weight with ion-exchanged water is added as a dispersant.
(3) A predetermined amount of ion-exchanged water is placed in the water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.) having 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, and about 2 ml of the Contaminon N is added to this water tank.
(4) The beaker of (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 electrolytic 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) Using a pipette, the electrolyte aqueous solution (5) in which the toner is dispersed is dropped 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 of Measuring Number Average Particle Size (D1) of Toner>
In step (7) of the method for measuring the weight average particle diameter (D4) of a toner, when the dedicated software is set to Graph/Number %, the “Average diameter” on the Analysis/Number statistics (arithmetic mean) screen is the number average particle diameter (D1).

<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 polycarboxylic 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 in the reactor was then reduced to 8.3 kPa and maintained for 1 hour, after which it 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 polyester resin L, which is a binder resin component, 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 polycarboxylic 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 reactor 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 a polyester resin H, which is a binder resin component, 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 one or more aliphatic compounds selected from the group consisting of aliphatic monocarboxylic acids and aliphatic monoalcohols shown in Table 2 were added in an amount of 7.0 mol% per 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.

<Production of Crushed Material for Toner>
Amorphous polyester resin L 80 parts by mass Amorphous polyester resin H 20 parts by mass Crystalline polyester resin 5 parts by mass Fischer-Tropsch wax (hydrocarbon wax, maximum endothermic peak temperature 90°C) 8 parts by mass C.I. Pigment Blue 15:3 7 parts by mass The above materials were mixed using a Henschel mixer (FM-75 type, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 20s ^-1 and a rotation time of 5 min, and then kneaded with a twin-screw kneader (PCM-30 type, manufactured by Ikegai Co., Ltd.). 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 Meter Co., Ltd. The kneaded product obtained was cooled and coarsely pulverized with a pin mill to a volume average particle size of 100 μm or less to obtain a coarsely pulverized product.

<Manufacturing Apparatus 1>
As the configuration of the pulverizing device, a mechanical pulverizer (Turbo Mill T250-CRS manufactured by Turbo Kogyo Co., Ltd., rotor shape RS type) was modified to provide a supply mechanism that can supply raw materials by accelerated injection and can freely adjust the supply direction. In other words, it is possible to change the speed of accelerated injection when supplying raw materials and the angle θ between the introduction direction of the material to be pulverized in the left diagram in FIG. 2 and the tangent direction at the raw material inlet. The ratio Lj/Lr of the distance Lj from the end of the rotor on the supply port 101 side to the raw material supply port 201 to the total length Lr of the rotor in FIG. 3 was set to 0.1. The configuration is shown in Table 1. The tooth configuration in Table 1 represents the shape of the rotor and the stator. In the parallel teeth, the interval Da between the concave and convex parts of the rotor and the stator was 1.3 mm, and the interval Db between the convex parts of the rotor and the stator was 1.0 mm.

<Manufacturing Apparatus 2>
The milling equipment was a modified mechanical mill (Turbo Mill T250-CRS, rotor type RS, manufactured by Turbo Kogyo Co., Ltd.), which could supply the raw material by accelerated injection and had a supply mechanism that could freely adjust the supply direction. The ratio of Lj/Lr was set to 0.3. The configuration is shown in Table 1.

<Manufacturing Equipment 3>
The mill used was a mechanical mill (Turbo Mill T250-CRS, rotor shape RS type, manufactured by Turbo Kogyo Co., Ltd.). The configuration is shown in Table 1.

<Manufacturing Apparatus 4>
The milling device was a modified mechanical mill (Turbo Mill T250-CRS, rotor shape RS type, manufactured by Turbo Kogyo Co., Ltd.), with the same raw material supply method as accelerated injection as in the manufacturing device 1, and with the rotor and stator having uneven teeth that mesh with each other as shown in Figure 5. The configuration is shown in Table 1.

<Toner Production Method 1>
The device 1 was operated with θ set to 55°, the feed rate of the crushed material set to 10 kg/h, the rotor speed set to 170 m/s, the cold air temperature set to -10°C, and the cold air volume set to 8 ^m3 /min. The conditions for accelerated injection were a nozzle diameter of 21.6 mm, a pressure of 0.5 MPa, and a flow rate of 0.5 L/min. The accelerated injection speed at this time was 22.7 m/s.

<Production Examples of Toner Production Methods 2 to 12>
In the toner production methods 2 to 12, the device configuration, the speed at which the material to be pulverized (coarsely pulverized material) is accelerated and sprayed, and θ were changed as shown in Table 2. The other operating conditions were the same as those in the production method 1.

Example 1
The pulverizer was operated in the same manner as in toner production method 1, the average particle sizes D4 and D1 were measured, and D4 and the particle size distribution index D4/D1 were evaluated.

[Evaluation of D4]
The particle size of the toner particles after the pulverization process was evaluated according to the following criteria.
A: D4 is less than 4.2 μm (very excellent)
B: D4 is 4.2 μm or more and less than 4.4 μm (excellent)
C: D4 is 4.4 μm or more and less than 4.6 μm (this is not a problem in the present invention)
D: D4 is 4.6 μm or more (not acceptable in the present invention)

[Evaluation of D4/D1]
The particle size distribution of the toner particles after the pulverization process was evaluated. The smaller the particle size distribution index D4/D1, the sharper the distribution. As described above, when the particle size distribution is sharp, there are fewer unnecessary particle size components to be removed in the classification process after the fine pulverization process. Therefore, it is possible to maintain high productivity. The evaluation criteria are as follows.
A: D4/D1 is less than 1.57 (very good)
B: D4/D1 is 1.57 or more and less than 1.59 (excellent)
C: D4/D1 is 1.59 or more and less than 1.62 (this is not a problem in the present invention)
D: D4/D1 is 1.62 or more (not acceptable in the present invention)

<Examples 2 to 7 and Comparative Examples 1 to 5>
Except for changing the production method, evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 3.

In Comparative Example 1, accelerated grinding was not performed for the material to be ground, and the material was fed in the normal manner. It is presumed that the poor evaluation of D4 was due to the lack of grinding effect caused by collisions during feeding.

In Comparative Example 2, the grinding teeth are interlocking teeth. The accelerated injected material collides directly with the rotor, but it is presumed that the poor evaluation of D4 was due to insufficient grinding in the subsequent grinding chamber.

Comparative example 3 is an example in which the raw material supply position is shifted toward the discharge port. The accelerated injected material collides directly with the rotor, but it is presumed that the poor evaluation of D4 was due to insufficient grinding in the subsequent grinding chamber.

Comparative Example 4 is an example in which the accelerated jet speed of compressed air was increased to 51.9 m/sec. It is presumed that the collision energy caused by the accelerated jet became excessive, resulting in over-pulverized toner particles, which resulted in a poor evaluation of D4/D1.

Comparative example 5 is an example in which the accelerated jet speed of compressed air was lowered to 8.8 m/sec. It is presumed that the collision energy was not sufficient for pulverization, resulting in a poor evaluation of D4.

101: supply port, 102: volute, 103: rotor, 104: stator, 105: rear chamber, 106: exhaust port, 107: central rotating shaft (rotating shaft), 108: cold air generator, 109: cold water supply port, 110: cold water exhaust port, 201: raw material supply port

Claims (2)

A method for producing a toner, comprising a step of finely pulverizing a material to be pulverized, the material containing a binder resin and a colorant, by a pulverizing means,
The crushing means is
A powder supply mechanism for supplying the material to be pulverized;
a stator having a plurality of protrusions and recesses on an inner circumferential surface;
a rotor attached to a central rotating shaft and having a plurality of protrusions and recesses on an outer circumferential surface;
A powder discharge port for discharging the finely pulverized material;
having
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;
The convex portions and concave portions present on the inner peripheral surface of the stator and the outer peripheral surface of the rotor are formed along the axial direction of the central rotation shaft,
The protruding portion of the stator and the protruding portion of the rotor face each other with a gap of 0.8 mm or more and 1.4 mm or less between them,
The material to be pulverized is accelerated and sprayed by the powder supply mechanism, and is supplied from a supply port so as to collide directly with the outer circumferential surface of the rotor. In a pulverization region formed by a gap between the stator and the rotor, the material is pulverized by the rotation of the rotor.
When the rotor is divided into four equal parts along the central rotation axis, and each of the four equal parts is designated as a first region to a fourth region along the flow of the material to be crushed,
(i) a position where the material to be pulverized is accelerated and jetted by the powder supply mechanism and collides with the rotor is a first region;
(ii) the powder discharge port is provided downstream of the flow of the material to be ground ;
The accelerated air velocity when the material to be pulverized is accelerated and sprayed is 10 m/sec or more and 50 m/sec or less when passing through the supply port.
A method for producing a toner comprising the steps of: The method for producing toner according to claim 1, wherein the powder supply mechanism supplies the material to be pulverized in a direction opposite to the direction of rotation of the rotor, and the angle θ between the introduction direction of the material to be pulverized, the powder supply mechanism, and the stator in a plane perpendicular to the rotation axis of the rotor is 20° or more and 80° or less.

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