JP7492405B2 - 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 image forming methods for visualizing electrophotography and electrostatic images, toner is used to develop electrophotography and electrostatic images. In recent years, full-color electrophotographic copiers have become widespread, and the printing market is now demanding high speed, high image quality, and high productivity while being compatible with a wide range of media (paper types), and the performance required of toner is also increasing.

Toner manufacturing methods are broadly divided into pulverization and polymerization methods, with pulverization being a simple manufacturing method. In the pulverization method, in order to achieve high developability and transferability, heat treatment of the toner particles obtained by pulverizing the mixed raw materials is effective (Patent Document 1). This is because the fine particles of external additives are fixed to the surface of the toner particles by heat treatment, creating a spacer effect between the toner particles.

When the toner particles obtained by pulverizing the mixed raw materials are heat-treated to obtain high adhesion of the external additives to the toner and high circularity of the toner, high thermal energy is applied to the toner. This tends to result in adverse effects such as an increase in particle size due to particle coalescence and a broadening of the particle distribution.

To address this issue, there is a method of adding a small-particle external additive before heat treatment to improve the fluidity of the toner particles and prevent the coalescence of the toner particles. There is also a method of transporting the toner particles at a high air speed to break up the agglomerations and prevent the coalescence of the toner particles.

JP 2013-20244 A

However, toner particles obtained by pulverizing the mixed raw materials have minute irregularities on the surface of the toner particles. Therefore, when small-particle-sized external additives are added as fluidizing agents or spacer agents before heat treatment, the external additives tend to be biased toward the recesses on the toner surface, making it difficult to achieve the effect of suppressing the coalescence of toner particles. Furthermore, when the toner particles are transported at high air speeds, the external additives may come off the toner particles, reducing their adhesion to the toner surface.

These issues become more pronounced when the production feed is increased in order to achieve high productivity. Thus, there is room for further improvement in terms of the increase in particle size and broadening of distribution due to the coalescence of toner particles during the toner heat treatment process, as well as the adhesion of external additives to the toner surface.

The object of the present invention is to solve the above problems, provide a method for producing a toner that is highly productive, suppresses particle size increase during heat treatment, and has a high rate of external additive adhesion.

a first heat treatment step for obtaining first heat-treated toner particles by heat-treating toner particles using a thermal sphering treatment device, the toner particles containing a binder resin and a release agent;
a mixing step of mixing the first heat-treated toner particles with inorganic fine particles to obtain a first heat-treated toner particle mixture;
a second heat-treating step of heat-treating the first heat-treated toner particle mixture using the thermal sphering processor to obtain second heat-treated toner particles;
A method for producing a toner comprising the steps of:
The thermal sphering treatment device comprises:
a treatment chamber for heat treating the toner particles or the first heat treated toner particle mixture;
a toner particle supply means for supplying said toner particles or said first heat-treated toner particle mixture to said treatment chamber;
hot air supplying means for supplying hot air for heat-treating the toner particles or the first heat-treated toner particle mixture supplied from the toner particle supplying means;
a recovery means for recovering the first heat-treated toner particles or the second heat-treated toner particles by discharging them to the outside of the treatment chamber through a discharge port provided at one end of the treatment chamber,
In the first heat treatment step, the speed of the toner particles supplied from the supply means is 25 m/sec or more and 100 m/sec or less,
The average circularity of the toner particles is C ₁ ,
The average circularity of the first heat-treated toner particles is C ₂ ,
When the average circularity of the second heat-treated toner particles is _C3 ,
The _C1 is 0.935 or more and 0.960 or less,
The _C3 is 0.960 or more and 0.980 or less,
A method for producing a toner, wherein C ₁ , C ₂ and C ₃ satisfy the relationships represented by the following formulas (1) and (2):
0.20≦ _C2 − _C1 / _C3 − _C1 ≦0.50 (1)
0.010≦ _C3 − _C1 (2)

The present invention provides a method for producing toner that is highly productive, suppresses particle size increase during heat treatment, and has a high rate of external additive adhesion.

FIG. 2 is a diagram of a thermal sphering treatment device used in the present invention.

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

The method for producing a toner according to the present invention comprises the steps of:
a first heat treatment step for obtaining first heat-treated toner particles by heat-treating toner particles using a thermal sphering treatment device, the toner particles containing a binder resin and a release agent;
a mixing step of mixing the first heat-treated toner particles with inorganic fine particles to obtain a first heat-treated toner particle mixture;
a second heat-treating step of heat-treating the first heat-treated toner particle mixture using the thermal sphering device to obtain second heat-treated toner particles,
The thermal sphering treatment device comprises:
a treatment chamber for heat treating the toner particles or the first heat treated toner particle mixture;
a toner particle supply means for supplying said toner particles or said first heat-treated toner particle mixture to said treatment chamber;
hot air supplying means for supplying hot air for heat-treating the toner particles or the first heat-treated toner particle mixture supplied from the toner particle supplying means;
a recovery means for recovering the first heat-treated toner particles or the second heat-treated toner particles by discharging them to the outside of the treatment chamber through a discharge port provided at one end of the treatment chamber,
In the first heat treatment step, the speed of the toner particles supplied from the toner particle supplying means is 25 m/sec or more and 100 m/sec or less,
The average circularity of the toner particles is C ₁ ,
The average circularity of the first heat-treated toner particles is C ₂ ,
When the average circularity of the second heat-treated toner particles is _C3 ,
The _C1 is 0.935 or more and 0.960 or less,
The _C3 is 0.960 or more and 0.980 or less,
The C ₁ , C ₂ and C ₃ satisfy the relationships shown in the following formulas (1) and (2).
0.20≦ _C2 − _C1 / _C3 − _C1 ≦0.50 (1)
0.010≦ _C3 − _C1 (2)

According to the inventors' research, the above manufacturing method can suppress the increase in particle size during heat treatment and produce a toner with a high rate of external additive adhesion.

The reasons why the toner manufacturing method according to the present invention can achieve superior effects not previously achieved are believed to be as follows:

In the toner manufacturing method according to the present invention, the average circularity _C1 of the toner particles before the heat treatment is 0.935 or more and 0.960 or less, and the average circularity _C3 of the second heat-treated toner particles after two heat treatments is 0.960 or more and 0.980 or less. Furthermore, the difference between the average circularity _C3 of the second heat-treated toner particles after two heat treatments and the average circularity _C1 of the toner particles before the heat treatment is 0.010 or more. This means that the change in circularity of the toner due to the heat treatment is large.

The toner particles obtained by grinding the mixed raw materials have a low degree of circularity, and in order to obtain a high degree of circularity, a large amount of thermal energy must be applied. In this case, the toner particles tend to aggregate together, and when heat-treated, the toner particles may coalesce, resulting in an increase in particle size and a broadening of the distribution.

The present invention is characterized in that the heat treatment is carried out in two steps.
The amount of change in the average circularity of the toner particles in the first heat treatment step, i.e., the value obtained by _C2 - _C1 , is 20% to 50% of the amount of change in the average circularity of the toner particles after the first heat treatment step and the second heat treatment step, i.e., the value obtained by _C3 - _C1 . In other words, the rate of change in the average circularity in the first heat treatment step is small. In the first heat treatment step, it is important to reduce the number of recesses on the particle surface of the toner particles obtained by pulverizing the mixed raw material, and the thermal energy applied to the toner particles is reduced, thereby suppressing the coalescence of the toner particles.

In the first heat treatment step, it is important that the speed of the toner particles before heat treatment, which are supplied into the device using gas from the toner particle supply means, is 25 m/sec or more and 100 m/sec or less. By keeping the toner particle speed within the above range, the agglomerations of the toner particles before heat treatment are broken down, and it is possible to suppress an increase in particle size and a broadening of the distribution due to coalescence during heat treatment.

The toner manufacturing method according to the present invention includes a mixing step between the first heat treatment step and the second heat treatment step, in which inorganic fine particles as an external additive are mixed with the first heat-treated toner particles to obtain a first heat-treated toner particle mixture. The toner particles before the heat treatment are made spherical by the first heat treatment step, and the number of recesses on the surface of the toner particles is reduced in the first heat-treated toner particles. This makes it possible to prevent the external additive from concentrating in the recesses when the external additive is added to the first heat-treated toner particles in the mixing step. Therefore, the external additive is uniformly added to the surface of the first heat-treated toner particles, and in the second heat treatment step, the fluidity of the toner and the spacer effect of the external additive can be increased, and the coalescence of the first heat-treated toner particles can be suppressed.

In addition, when there are minute protrusions on the surface of toner particles obtained by pulverizing the mixed raw materials, the external additive has difficulty adhering to the protrusions on the toner particle surface, and the external additive that cannot adhere is liberated from the toner surface, which may result in poor adhesion of the external additive. In the toner manufacturing method according to the present invention, the unevenness of the toner particle surface is reduced in the first heat treatment step, and then a process of mixing with the external additive is carried out in the mixing step, and then the second heat treatment step is carried out. This makes it possible to increase the adhesion rate of the external additive to the toner particle surface.

In the toner manufacturing method according to the present invention, the speed of the first heat-treated toner particle mixture supplied from the toner particle supply means in the second heat treatment step is preferably 5 m/sec or more and 20 m/sec or less. By having the speed of the first heat-treated toner particle mixture supplied from the toner particle supply means in the second heat treatment step within the above range, it is possible to highly effectively break up the agglomerations of the first heat-treated toner particle mixture and maintain the external additives during heat treatment. Therefore, it is possible to further suppress the increase in particle size during heat treatment, and toner with a higher adhesion rate of the external additives can be manufactured.

In the toner manufacturing method according to the present invention, it is preferable that the above-mentioned mixing step is a second mixing step, and that a first mixing step of mixing the toner particles with inorganic fine particles is further provided before the first heat treatment step. By mixing the toner particles with inorganic fine particles in the first mixing step before the first heat treatment step, the fluidity of the toner particles can be increased in the first heat treatment step, and the spacer effect of the external additive can be enhanced, so that the increase in particle size during heat treatment can be further suppressed.

The inorganic fine particles used in the first mixing step and the inorganic fine particles used in the second mixing step may be the same type or different types.

<Toner Manufacturing Method>
Next, a procedure for producing the toner according to the production method of the present invention will be described.
First, in the raw material mixing process, at least a binder resin and a release agent are weighed out in a predetermined amount as toner internal additives, and then mixed. The release agent suppresses the occurrence of hot offset during heat fixing of the toner. If necessary, a colorant, a dispersant for dispersing 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 melted and kneaded to melt the resins and disperse the release agent 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. For this reason, for example, a KTK twin-screw extruder manufactured by Kobe Steel, Ltd., a TEM twin-screw extruder manufactured by Toshiba Machine Co., Ltd., a PCM twin-screw extruder manufactured by Ikegai Corporation, a twin-screw extruder manufactured by KCK Corporation, and a Co-Kneader manufactured by Buss Co., Ltd. are commonly used. Furthermore, the resin composition obtained by melt-kneading the toner raw materials is rolled with a two-roller or the like after melt-kneading, and cooled through a cooling process in which it is cooled with water or the like.

The cooled resin composition obtained above is then pulverized to the desired particle size in a pulverization process to produce toner particles. In the pulverization process, the resin composition is first coarsely pulverized using a crusher, hammer mill, feather mill, or the like. It is then finely pulverized using a mechanical pulverizer such as an Innomizer (manufactured by Hosokawa Micron Corporation), a Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.), a Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), or a Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.). In this way, the resin composition is pulverized stepwise to the desired particle size in the pulverization process.

The toner particles obtained above may be subjected to classification processing such as removing fine particles and removing coarse particles as necessary.

Next, in the heat treatment process, the obtained toner particles are heat-treated using a thermal sphering treatment device, an example of which is shown in Figure 1.

The thermal sphering device has a processing chamber 6 for thermally processing the toner particles or the first heat-treated toner particle mixture, a toner particle supplying means for supplying the toner particles or the first heat-treated toner particle mixture to the processing chamber 6, a hot air supplying means 7 for supplying hot air for thermally processing the toner particles or the first heat-treated toner particle mixture supplied from the toner particle supplying means, and a recovery means 10 for discharging the first heat-treated toner particles or the second heat-treated toner particles from the processing chamber 6 through an outlet provided in the processing chamber 6 and recovering them.

The thermal sphering treatment device shown in FIG. 1 further has a regulating means 9 as a cylindrical member, and the treatment chamber 6 has a cylindrical shape that covers the outer peripheral surface of the regulating means 9.

The hot air supply means 7 is provided at one end of the cylindrical treatment chamber 6 so that the hot air flows while rotating inside the cylindrical treatment chamber 6.

The toner particle supply means is composed of multiple supply pipes 5 provided on the outer periphery of the processing chamber 6.

Furthermore, the discharge outlet provided in the treatment chamber 6 is provided on the outer periphery of the end of the treatment chamber 6 opposite the side where the hot air supply means 7 is provided, so as to be on an extension of the rotation direction of the toner particles or the first heat-treated toner particle mixture.

The heat treatment using the thermal sphering treatment device having the above-mentioned configuration will be described below.
The mixture supplied by the raw material constant-quantity supplying means 1 is introduced into an inlet pipe 3, which is installed on the extension line of the raw material constant-quantity supplying means 1, by compressed gas adjusted by a compressed gas flow rate adjusting means 2. The mixture passing through the inlet pipe 3 is uniformly dispersed by a conical protruding member 4 provided in the center of the inlet pipe 3, and is introduced into eight supply pipes 5 that radiate outward, and is introduced into a treatment chamber 6 where heat treatment is carried out.

At this time, the flow of the mixture supplied to the processing chamber 6 is regulated by a regulating means 9 for regulating the flow of the mixture provided in the processing chamber 6. Therefore, the mixture supplied to the processing chamber is heat-treated while swirling inside the processing chamber 6, and then cooled.

The heat for heat-treating the supplied mixture is supplied from the hot air supply means 7, distributed by the distribution member 12, and introduced into the treatment chamber 6 by the swirling member 13 for swirling the hot air in a spiral shape. The swirling member 13 for swirling the hot air has multiple blades, and the swirling of the hot air can be controlled by the number and angle of the blades. The hot air is supplied from the hot air supply means outlet 11.

The heat-treated toner particles are cooled by cold air supplied from cold air supply means 8 (cold air supply means 8-1, cold air supply means 8-2, and cold air supply means 8-3).

The cooled toner particles are then collected by the collection means 10 at the bottom of the processing chamber. A blower (not shown) is provided beyond the collection means, which transports the toner particles by suction.

The powder particle supply port 14 is arranged so that the swirling direction of the supplied mixture and the swirling direction of the hot air are the same, and the recovery means 10 of the thermal sphering treatment device is arranged on the outer periphery of the treatment chamber so as to maintain the swirling direction of the swirled powder particles. The cold air supplied from the cold air supply means 8 is configured to be supplied horizontally and tangentially from the outer periphery of the device to the circumferential surface inside the treatment chamber.

In the toner manufacturing method according to the present invention, inorganic fine particles are added to the first heat-treated toner particles in a mixing step between the first heat-treatment step and the second heat-treatment step. It is also preferable to add inorganic fine particles to the toner particles before the first heat-treatment step. The following method can be used to add inorganic fine particles to the first heat-treated toner particles or toner particles before heat treatment. That is, first, the first heat-treated toner particles or toner particles before heat treatment are mixed with a predetermined amount of various known external additives. Next, the resulting mixture is stirred and mixed using a high-speed mixer that applies shear force to powders, such as a Henschel mixer, Mechano Hybrid (manufactured by Nippon Coke Corporation), a Super Mixer, or a Nobilta (manufactured by Hosokawa Micron Corporation), as an external adder.

<Toner raw materials>
Next, the raw materials used in the production of the toner will be described.

<Binder resin>
As the binder resin used in the toner, 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 preferably used, and from the viewpoint of achieving both low-temperature fixing property and hot offset resistance, low-molecular-weight polyester and high-molecular-weight polyester may be used in combination. Furthermore, from the viewpoint of further improving low-temperature fixing property and blocking resistance during storage, crystalline polyester may be used as a plasticizer.

<Release Agent>
Examples of the release agent used in the toner include low molecular weight polyolefins, silicone wax, fatty acid amides, ester waxes, carnauba wax, hydrocarbon waxes, etc. These release agents may be used alone or in combination of two or more.
The release agent may be mixed with the synthetic raw materials of the binder resin when synthesizing the binder resin used in the production of toner particles, or may be added in a raw material mixing step during the production of the toner. The content of the release agent in the toner is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin.

<Inorganic fine particles>
As described above, in the toner manufacturing method according to the present invention, inorganic fine particles are added to the first heat-treated toner particles in the mixing step between the first heat-treatment step and the second heat-treatment step. It is also preferable to add inorganic fine particles to the toner particles before the first heat-treatment step. The inorganic fine particles are mixed as an external additive with the toner particles before the heat treatment or the first heat-treated toner particles. As the inorganic fine particles, silica, titanium oxide, aluminum oxide or strontium titanate are preferred. It is preferable that the inorganic fine particles are hydrophobized with a hydrophobizing agent such as a silane compound, silicone oil or a mixture thereof.

The number-average particle size of the inorganic microparticles is preferably 10 nm or more and 300 nm or less. In order to simultaneously improve fluidity and stabilize durability, multiple types of inorganic microparticles with number-average particle sizes in the above ranges may be used in combination.

The content of inorganic fine particles is preferably 0.01 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the first heat-treated toner particle mixture.

<Coloring Agent>
Examples of colorants that can be used in the method for producing the toner according to the present invention include the following.
That is, examples of the colorant include known organic pigments or oil-based dyes, carbon black, and magnetic materials.
Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds.
Examples of 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.
Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.
Examples of black colorants include carbon black, magnetic materials, and those toned to black using the above-mentioned yellow colorants, magenta colorants, and cyan colorants.
The colorants may be used alone or in combination of two or more.

The methods for measuring various physical properties of the toner particles will be described below.
<Method of measuring weight average particle size (D4) of toner particles>
The weight average particle diameter (D4) of the toner particles can be calculated by measuring with an effective number of measuring channels of 25,000 channels using the following device and software, and analyzing the measurement data.
- "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), a precision particle size distribution measuring device using the narrow hole electrical resistance method equipped with a 50 μm aperture tube
- Dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) included with the above device for setting measurement conditions and analyzing measurement data

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

Before carrying out the measurements and analyses, the dedicated software is set up as follows.
In the "Change Standard Measurement Method (SOM) Screen" of the dedicated software, the total count number in the control mode is set to 50,000 particles, the number of measurements is set to 1, and the Kd value is set to the value obtained using "Standard Particle 10.0 μm" (manufactured by Beckman Coulter). The threshold and noise level are automatically set by pressing the threshold/noise level measurement button. In addition, the current is set to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and the aperture tube flush after measurement is checked.
In the "Pulse to particle size conversion setting screen" of the dedicated software, 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 made specifically for the "Multisizer 3," set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture flush" function of the analysis software to remove dirt and air bubbles from inside the aperture tube.

(2) Place about 30 ml of the aqueous electrolyte solution in a 100 ml flat-bottom glass beaker. Add about 0.3 ml of a solution of "Contaminon N" (a 10% aqueous solution of a neutral detergent for cleaning precision measuring instruments with a pH of 7, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted 3 times by mass with ion-exchanged water 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 a specified amount of ion-exchanged water in a water tank equipped with this ultrasonic disperser, and add approximately 2 ml of the Contaminon N to this water tank.

(4) Set the beaker from (2) in the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the electrolyte solution surface in the beaker is maximized.

(5) While the electrolyte solution in the beaker in (4) is being irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolyte solution and dispersed. Then, ultrasonic dispersion processing is continued for another 60 seconds. During ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted so that it is between 10°C and 40°C.

(6) Using a pipette, add the electrolyte aqueous solution (5) containing dispersed toner to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to approximately 5%. Then, measurements are 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 average circularity>
The average circularity of the toner particles can be measured using a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions at the time of calibration work.

The specific measurement method is as follows.
First, about 20 ml of ion-exchanged water from which impurities such as solids have been removed is placed in a glass container, and about 0.2 ml of a solution 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 as a dispersant.

Add approximately 0.02 g of the measurement sample and disperse it for 2 minutes using an ultrasonic disperser to obtain a dispersion for measurement. At this time, cool the dispersion appropriately so that the temperature is between 10°C and 40°C. As the ultrasonic disperser, use a tabletop ultrasonic cleaner disperser (VS-150 (Velvoclear)) with an oscillation frequency of 50 kHz and an electrical output of 150 W. A specified amount of ion-exchanged water is placed in the water tank, and approximately 2 ml of the Contaminon N is added to this water tank.

The measurements were performed using the flow-type particle image analyzer equipped with a standard objective lens (10x), and the sheath liquid used was the particle sheath "PSE-900A" (manufactured by Sysmex Corporation).

The dispersion liquid prepared according to the above procedure is introduced into the flow type particle image analyzer, and 3,000 toner particles are measured in HPF measurement mode and total count mode. The binarization threshold for particle analysis is set to 85%, and the analyzed particle size is limited to a circle equivalent diameter of 1.985 μm or more and less than 39.69 μm, and the average circularity of the toner particles is calculated.

When performing measurements, automatic focus adjustment is performed using standard latex particles before the start of the measurement. Standard latex particles are used (Duke Scientific's "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A" diluted with ion-exchanged water). After that, it is preferable to perform focus adjustment every two hours from the start of the measurement.

In the examples of this application, a flow-type particle image analyzer was used that had been calibrated by Sysmex Corporation and had a calibration certificate issued by Sysmex Corporation. Measurements were performed under the same measurement and analysis conditions as when the calibration certificate was received, except that the particle size analyzed was limited to a circle equivalent diameter of 1.985 μm or more and less than 39.69 μm.

<Method for measuring adhesion rate of inorganic fine particles>
1) Method of Water Washing Treatment Water washing treatment can be carried out as follows.
First, prepare the following materials:
- A sucrose solution prepared by dissolving 20.7 g of sucrose (Kishida Chemical Co., Ltd.) in 10.3 g of ion-exchanged water - 6 mL of Contaminon N (a neutral detergent for cleaning precision measuring instruments with a pH of 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.)
These are placed in a 30 mL glass vial (for example, VCV-30, manufactured by Nichiden Rika Glass Co., Ltd., outer diameter: 35 mm, height: 70 mm) and thoroughly mixed to prepare a dispersion. 1.0 g of toner particles are added to this vial, and the toner is left to stand until it naturally settles to prepare a pre-treatment dispersion. This dispersion is shaken with a shaker (YS-8D type: manufactured by Yayoi Co., Ltd.) at a shaking speed of 200 rpm for 5 minutes to detach the inorganic fine particles from the toner particle surface. The inorganic fine particles detached here are inorganic fine particles that are not adhered to the toner particles. Separation of the inorganic fine particles adhered to the toner particles and the inorganic fine particles detached from the toner particle surface is performed using a centrifuge. The centrifugation process is performed, for example, under conditions of 3700 rpm for 30 minutes. Next, the toner particles to which the inorganic fine particles are adhered are collected by suction filtration, and dried to obtain toner particles after washing with water.

2) Method for measuring the adhesion rate of inorganic fine particles The method for measuring the adhesion rate of silica fine particles is shown below as an example. First, the amount of silica contained in the toner particles before the water washing treatment is quantified. This is done by measuring the Si element strength in the toner particles using a wavelength dispersive X-ray fluorescence analyzer Axios advanced (manufactured by PANalytical). Next, in the same manner, the Si element strength in the toner particles after the water washing treatment is measured. The adhesion rate (%) is calculated as follows:
(Si element intensity in toner particles after water washing treatment/Si element intensity in toner particles before water washing treatment)×100
It can be calculated as follows.

In the following examples, the parts are based on parts by weight.
<Production Example of Amorphous Polyester Resin L>
Polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane: 72.0 parts by mass (0.200 moles; 100.0 mol% based on the total number of moles of polyhydric alcohol)
Terephthalic acid: 28.0 parts by mass (0.169 moles; 96.0 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 while stirring.
The pressure inside the reaction vessel was then reduced to 8.3 kPa and maintained at that level for 1 hour, after which the vessel was cooled to 180° C. and returned to atmospheric pressure.
Trimellitic anhydride: 1.3 parts by mass (0.007 moles; 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 was obtained.

<Production Example of Amorphous Polyester Resin H>
Polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane: 72.3 parts by mass (0.200 moles; 100.0 mol% based on the total number of moles of polyhydric alcohol)
Terephthalic acid: 18.3 parts by mass (0.110 moles; 65.0 mol% based on the total number of moles of polycarboxylic acids)
Fumaric acid: 2.9 parts by mass (0.025 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 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 (0.034 moles; 20.0 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 15 hours while maintaining the temperature at 160°C. After it was confirmed that the softening point measured in accordance with ASTM D36-86 had reached 137°C, the temperature was reduced to stop the reaction, and an amorphous polyester resin H 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 the atmosphere in the flask was replaced with nitrogen gas, the temperature was gradually raised with stirring, and the mixture was reacted for 3 hours at 140° C. with stirring.
Next, the above materials were added, the pressure inside the reaction vessel was reduced to 8.3 kPa, and the temperature was maintained at 200° C. while allowing the reaction to proceed for 4 hours.
Furthermore, the pressure in the reaction vessel was gradually released to return to normal pressure, and then 7.0 mol % of stearic acid was added relative to 100.0 mol % of the raw material monomer, and the mixture was reacted at 200° C. for 2 hours under normal pressure.
Thereafter, the pressure inside the reaction vessel was reduced again to 5 kPa or less, and the mixture was reacted at 200° C. for 3 hours to obtain a crystalline polyester resin.

[Production Example of Inorganic Fine Particles]
Silica fine particles were used as the inorganic fine particles.
A double-tube structured hydrocarbon-oxygen mixed burner capable of forming an inner flame and an outer flame was used as the combustion furnace for producing silica microparticles. A two-fluid nozzle for injecting slurry was grounded at the center of the burner, and the raw material silicon compound was introduced. A flammable hydrocarbon-oxygen gas was injected from around the two-fluid nozzle, forming an inner flame and an outer flame, which are a reducing atmosphere. The size, temperature, and flame length of the reducing atmosphere were adjusted by controlling the amount and flow rate of the flammable gas and oxygen. Silica microparticles were formed from the silicon compound in the flame, and were then fused until the desired particle size was reached. The silica microparticles were then cooled and collected using a bag filter or the like to obtain silica microparticles.
Silica microparticles were produced using hexamethylcyclotrisiloxane as the raw silicon compound, and 100 parts by mass of the obtained silica microparticles were surface-treated with 4% by mass of hexamethyldisilazane. The obtained silica microparticles were designated as inorganic microparticles 1, and the average particle size of inorganic microparticles 1 is shown in Table 1.

[Production Example of Inorganic Fine Particles 2]
Inorganic fine particles 2 were produced in the same manner as inorganic fine particles 1, except that the production conditions were changed so that the average particle size would be the value shown in Table 1.

<Production Example of Toner Particles 1 before Heat Treatment>
Amorphous polyester resin L 70 parts by mass Amorphous polyester resin H 30 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 20 s ^-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 kneaded product obtained was cooled and coarsely pulverized with a pin mill to a weight average particle size of 100 μm or less to obtain a coarsely pulverized product. The obtained coarsely pulverized product was finely pulverized with a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.). The resulting finely pulverized material was classified in a classifier (Faculty F-300, manufactured by Hosokawa Micron Corporation) by adjusting the rotation speed of the classification rotor and the dispersion rotor so as to obtain the target particle size and circularity, thereby obtaining toner particles. 2.00 parts by mass of inorganic fine particles 1 were added to 100 parts by mass of the obtained toner particles, and mixed in a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) under conditions of a rotation speed of 15 s ^-1 and a rotation time of 3 min, thereby obtaining pre-heat-treated toner particles 1. Table 2 shows the weight-average particle size and average circularity C ₁ of the obtained pre-heat-treated toner particles 1.

<Production Examples of Toner Particles 2 to 18 before Heat Treatment>
The use or non-use of inorganic fine particles or the type of inorganic fine particles used was changed as shown in Table 2, and further, the production conditions were appropriately changed so that the weight average particle size and average circularity _C1 of the obtained toner particles were the values shown in Table 2. Except for that, pre-heat-treated toner particles 2 to 18 were produced in the same manner as pre-heat-treated toner particles 1, to obtain pre-heat-treated toner particles 2 to 18.

<Production Example of First Heat-Treated Toner Particles 1>
Using the toner particles 1 before heat treatment, a heat treatment was carried out as a first heat treatment step by the thermal sphering treatment device shown in Fig. 1 to obtain first heat-treated toner particles 1. The feed amount was carried out under two conditions of 10.0 kg/h and 20 kg/h. The treatment conditions were as follows, and the hot air temperature was adjusted so as to obtain a desired circularity.
Air supply volume to the treatment chamber: 1.0 ^m3 /min
Wind speed in supply flow path: 40 m/sec
Hot air flow rate: 6.7 ^m3 /min
・Cool air temperature E: -5℃
Cold air flow rate: 3.5 ^m3 /min
・ Absolute moisture content of cold air: 3g/ ^m3
Blower air volume: 13 ^m3 /min
Here, the wind speed in the supply flow passage is the speed of the pre-heat-treated toner particles 1 supplied to the treatment chamber. Table 3 shows the weight-average particle size and average circularity _C2 of the obtained first heat-treated toner particles 1.

<Production Examples of First Heat-Treated Toner Particles 2 to 18>
The type of pre-heat-treated toner particles used and the heat treatment conditions were changed as shown in Table 3. Except for that, first heat-treated toner particles 2 to 18 were produced in the same manner as first heat-treated toner particles 1, and the weight average particle diameter and average circularity _C1 of the obtained first heat-treated toner particles 2 to 18 are shown in Table 3.
The first heat-treated toner particles 14 and 16 were treated by narrowing the diameter of the supply pipe in order to increase the maximum wind speed in the supply passage.

<Production Example of First Heat-Treated Toner Particle Mixture 1>
100 parts by mass of the first heat-treated toner particles 1 were prepared, and 1.00 parts by mass of the inorganic fine particles 2 were added thereto. Thereafter, the mixture was mixed using a Henschel mixer (FM-75 type, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed ^{of 15} s for a rotation time of 2 min to obtain a first heat-treated toner particle mixture 1.

<Production Examples of First Heat-Treated Toner Particle Mixtures 2 to 17>
Except for changing the type of the first heat-treated toner particles used as shown in Table 4, the first heat-treated toner particle mixtures 2 to 17 were produced in the same manner as in the production example of the first heat-treated toner particle mixture 1, to obtain first heat-treated toner particle mixtures 2 to 17.

<Production Example of Second Heat-Treated Toner Particles 1>
The first heat-treated toner particle mixture 1 was used and heat-treated as a second heat-treatment step by the thermal sphering treatment device shown in Fig. 1 to obtain second heat-treated toner particles 1. The feed rate was 10 kg/h. The other heat-treatment conditions were as follows, and the hot air temperature was adjusted to obtain the desired circularity.
Air supply volume to the treatment chamber: 0.2 ^m3 /min
Maximum wind speed in supply flow path: 10 m/sec
Hot air flow rate: 6.7 ^m3 /min
・Cool air temperature E: -5℃
Cold air flow rate: 3.5 ^m3 /min
・ Absolute moisture content of cold air: 3g/ ^m3
Blower air volume: 12 ^m3 /min
The weight average particle diameter and average circularity _C3 of the obtained second heat-treated toner particles 1 are shown in Table 5.

<Production Examples of Second Heat-Treated Toner Particles 2 to 17>
Second heat-treated toner particles 2 to 17 were obtained in the same manner as for second heat-treated toner particles 1, except that the materials and conditions were changed as shown in Table 5. The weight average particle diameter and average circularity _C3 of the obtained second heat-treated toner particles 2 to 17 are shown in Table 5.

<Examples 1 to 14 and Comparative Examples 1 to 4>
The change in the weight average particle size of the pre-heat-treated toner particles due to the heat treatment and the adhesion rate of the external additive in the second heat-treated toner particles 1 were measured. The types of the pre-heat-treated toner particles and the types of the second heat-treated toner particles used in each Example and Comparative Example are as shown in Table 6.

<Change in weight average particle size of toner particles before and after heat treatment>
When the weight average particle diameter of the toner particles before the heat treatment is _D1 and the weight average particle diameter of the second heat treated toner particles is _D2 , the change in particle diameter _D2 - _D1 was evaluated according to the following evaluation criteria. However, in Comparative Example 4, the weight average particle diameter of the first heat treated toner particles was set to _D2 . It was determined that the effects of the present invention were obtained when the particle diameter was C or higher. The evaluation results are shown in Table 6.
(Evaluation criteria)
A: _D2 - _D1 is 0.1 μm or less (very excellent)
B: _D2 - _D1 is greater than 0.1 μm and is 0.3 μm or less (good)
C: _D2 - _D1 is greater than 0.3 μm and is 0.5 μm or less (this is not a problem in the present invention).
D: _D2 - _D1 is greater than 0.5 (not acceptable in the present invention)

<Adhesion rate of external additives>
The adhesion rate of the external additive in the second heat-treated toner particles was evaluated by the method described above. However, in Comparative Example 4, the adhesion rate of the external additive in the first heat-treated toner particles was evaluated. It was determined that the effect of the present invention was obtained when the result was C or higher. The evaluation results are shown in Table 6.
(Evaluation criteria)
A: Adhesion rate is 85% or more (very good)
B: Adhesion rate is 80% or more and less than 85% (good)
C: Adhesion rate is 75% or more and less than 80% (this is a level that does not cause problems in the present invention)
D: Sticking rate is less than 75% (not acceptable in the present invention)

1. Means for quantitatively supplying raw material 2. Means for adjusting compressed gas flow rate 3. Introduction pipe 4. Projecting member 5. Supply pipe 6. Treatment chamber 7. Means for supplying hot air 8. Means for supplying cold air 9. Restricting means 10. Recovery means 11. Outlet of means for supplying hot air 12. Distribution member 13. Swirling member 14. Powder particle supply port

Claims (4)

a first heat treatment step for obtaining first heat-treated toner particles by heat-treating toner particles using a thermal sphering treatment device, the toner particles containing a binder resin and a release agent;
a mixing step of mixing the first heat-treated toner particles with inorganic fine particles to obtain a first heat-treated toner particle mixture;
a second heat-treating step of heat-treating the first heat-treated toner particle mixture using the thermal sphering processor to obtain second heat-treated toner particles;
A method for producing a toner comprising the steps of:
The thermal sphering treatment device comprises:
a treatment chamber for heat treating the toner particles or the first heat treated toner particle mixture;
a toner particle supply means for supplying said toner particles or said first heat-treated toner particle mixture to said treatment chamber;
hot air supplying means for supplying hot air for heat-treating the toner particles or the first heat-treated toner particle mixture supplied from the toner particle supplying means;
a recovery means for recovering the first heat-treated toner particles or the second heat-treated toner particles by discharging them to the outside of the treatment chamber through a discharge port provided in the treatment chamber,
In the first heat treatment step, the speed of the toner particles supplied from the toner particle supplying means is 25 m/sec or more and 100 m/sec or less,
The average circularity of the toner particles is C ₁ ,
The average circularity of the first heat-treated toner particles is C ₂ ,
When the average circularity of the second heat-treated toner particles is _C3 ,
The _C1 is 0.935 or more and 0.960 or less,
The _C3 is 0.960 or more and 0.980 or less,
A method for producing a toner, wherein C ₁ , C ₂ and C ₃ satisfy the relationships represented by the following formulas (1) and (2):
0.20≦ _C2 − _C1 / _C3 − _C1 ≦0.50 (1)
0.010≦ _C3 − _C1 (2) The method for producing toner according to claim 1, wherein the speed of the first heat-treated toner particle mixture supplied from the toner particle supply means is 5 m/sec or more and 20 m/sec or less. The mixing step is a second mixing step,
3. The method for producing a toner according to claim 1, further comprising a first mixing step of mixing the toner particles with inorganic fine particles before the first heat treatment step. The thermal sphering treatment device further includes a cylindrical member,
the processing chamber has a cylindrical shape surrounding the outer circumferential surface of the cylindrical member,
the hot air supplying means is provided on one end side of the cylindrical shape of the processing chamber so that the hot air flows while rotating inside the cylindrical processing chamber;
the toner particle supply means is composed of a plurality of particle supply ports provided on the outer periphery of the processing chamber,
4. The method for producing a toner according to claim 1, wherein the discharge outlet is provided on an outer periphery of an end of the treatment chamber on a side opposite to the side where the hot air supply means is provided, so as to be on an extension line of a rotation direction of the toner particles or the first heat-treated toner particle mixture.

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