JP2023170729A - Toner manufacturing method - Google Patents

Abstract

To provide a toner manufacturing method capable of achieving a smaller particle diameter.SOLUTION: A toner manufacturing method includes: a melting-kneading step of obtaining a melted-kneaded material by melting and kneading a resin composition containing a binder resin and inorganic fine particles; and a pulverizing step of obtaining a pulverized material by pulverizing a cooled solidified material after cooling and solidifying the melted-kneaded material. When the outflow start temperature of the binder resin is T1(°C), the thermal expansion coefficient of the inorganic fine particles is always -0.1×10-6(/K) or less in a temperature range of 30°C or more and T1°C or less.SELECTED DRAWING: None

Description

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

In recent years, electrophotographic full-color copying machines have become widespread, and their application to the printing market is progressing. In the printing market, there is a growing demand for high speed, high image quality, and high productivity while supporting a wide range of media (paper types). In toner, high image quality can be achieved by reducing the particle size.
Toners manufactured through melt-kneading and pulverization processes have the advantage of good pigment dispersibility and a wide color gamut. However, in the mechanical pulverizers (Patent Documents 1, 2, etc.) that are often used as pulverizers, the energy required for pulverization is large, and it is difficult to reduce the particle size compared to polymerized toners.
On the other hand, there has been an attempt to improve the crushability by adding inorganic fine particles to toner particles (Patent Document 3).

Japanese Patent Application Publication No. 2005-21768 JP2011-237816A Japanese Patent Application Publication No. 2015-132645

However, in the technique disclosed in Patent Document 3, the particle size of the toner is too large to achieve even higher image quality, and it is insufficient to reduce the particle size.
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for pulverizing toner that can solve the above-mentioned problems and reduce the particle size.

The present invention provides a melt-kneading process for obtaining a melt-kneaded product by melt-kneading a resin composition containing a binder resin and inorganic fine particles, and a process of cooling and solidifying the melt-kneaded product, and then pulverizing the cooled and solidified product. A method for producing a toner, the method comprising: a pulverizing step to obtain a toner;
When the outflow start temperature of the binder resin is T1 (°C), the inorganic fine particles always have a coefficient of thermal expansion of -0.1×10 ^-6 (/K) or less in the temperature range of 30°C or more and T1°C or less. The present invention relates to a method for manufacturing a toner characterized by the following.

According to the present invention, it is possible to provide a toner pulverization method that can reduce the particle size.

FIG. 2 is a schematic diagram of a mechanical crusher suitable for fine pulverization in the pulverization process of the present invention. 1 is a schematic diagram of a pulverization system suitable for pulverization in the pulverization process of the present invention.

In a toner manufacturing method using mechanical pulverization, pulverization is performed by colliding coarsely pulverized materials with a rotor rotating at high speed, or by causing toner particles to collide with each other using a jet. In the case of a toner to which an internal additive (filler) is added, it is assumed that stress concentration occurs around the filler during pulverization, making the toner more likely to break, that is, improving pulverizability. As a result of the inventors' studies as a manufacturing method to make the particle size smaller, it was found that the grindability was further improved by incorporating inorganic fine particles with a negative coefficient of thermal expansion (linear expansion coefficient) into the coarsely pulverized material. I found out.

Although the mechanism by which particle size can be further reduced by the pulverization method of the present invention is currently not clear, the inventors of the present invention assume the following.

Usually, substances have a positive coefficient of thermal expansion, and have the property of expanding when heated and contracting when cooled. On the other hand, a substance with a negative coefficient of thermal expansion has the property of contracting when heated and expanding when cooled. In the present invention, the inorganic fine particles having a negative coefficient of thermal expansion are dispersed throughout the resin (mainly the binder resin) constituting the toner in the kneading step. When the kneaded material that has reached a high temperature is subsequently cooled, the resin contracts, whereas the inorganic fine particles having a negative coefficient of thermal expansion expand. When the resin has fluidity at high temperatures, there is no difference from the conventional method, but when the temperature decreases and the fluidity of the resin decreases, the difference becomes more noticeable. In particular, the resin loses its fluidity when it is cooled below the temperature at which it begins to flow out in a flow tester, but it continues to shrink as it cools down to room temperature (approximately 30° C.). On the other hand, since inorganic fine particles having a negative coefficient of thermal expansion continue to expand upon cooling, it is assumed that the expanding inorganic fine particles cause minute cracks in the solidified resin. Conventionally, the improvement in crushability was only due to the effect of stress concentration by fillers, but by including inorganic fine particles with a negative coefficient of thermal expansion, which causes cracks to occur, an effect that surpasses conventional crushability was obtained. thinking.

A preferred method for producing toner in the present invention will be described below in detail.

<Inorganic fine particles>
The material with a negative coefficient of thermal expansion is not particularly limited, but since it is necessary to cause cracks in the resin during the cooling process, it is necessary to use inorganic fine particles. For example, a material having rubber properties may have a negative coefficient of thermal expansion, but it is presumed that rubber cannot cause cracks because it has elasticity. Examples of inorganic fine particles having a negative coefficient of thermal expansion include zirconium phosphate, zirconium tungstate phosphate, neoceram, and faujasite. Particularly preferred is hexagonal zirconium phosphate. Although the details are not clear, it is believed that this is because the specific gravity is relatively light and it is easy to increase the number of cracks.

Since the present invention is a toner manufacturing method by pulverization, the inorganic fine particles have a preferable particle size. The number average particle diameter is preferably 0.3 μm or more and 3.0 μm or less, more preferably 0.5 μm or more and 3.0 μm or less. When the size is within this range, the effect of creating cracks due to the difference between the expansion characteristics of the inorganic fine particles and the cooling characteristics of the resin during cooling is likely to occur, and the toner pulverizability is further enhanced.

Furthermore, in order to cause cracks, the viscosity of the resin needs to be high due to the assumed mechanism described above. In the present invention, the effect of having a negative coefficient of thermal expansion is greatest in the range of 30° C. from the outflow start temperature (T1° C.) of the binder resin. In other words, it is necessary that the coefficient of thermal expansion is always -0.1×10 ^-6 (/K) or less in the relevant temperature range, and the coefficient of thermal expansion is greater than -0.1×10 ^-6 (/K). In this case, only the effect of the conventional filler can be obtained, and the crushability does not improve significantly.

Regarding the amount added, it is preferably 0.3 volume % or more and 6.5 volume % or less, and more preferably 1.5 volume % or more and 4.5 volume % or less, based on the resin composition. If the amount is too small, cracks cannot be formed, and if it is too large, agglomeration occurs, so the crushability is not improved and the toner performance is also thought to be affected.

<Toner raw materials>
Next, raw materials for toner particles containing at least a binder resin and a colorant used in the present invention, other than the above-mentioned inorganic fine particles, will be explained.

<Binder resin>
As the binder resin used in the toner used in electrophotography, general resins can be used, such as polyester resin, styrene-acrylic acid copolymer, polyolefin resin, vinyl resin, fluororesin, phenol resin, Examples include silicone resin and epoxy resin. Among these, amorphous polyester resins are used from the viewpoint of improving low-temperature fixing properties, and it is known that low-molecular-weight polyesters and high-molecular-weight polyesters are used in combination from the viewpoint of achieving both low-temperature fixing properties and hot offset resistance. ing. Further, from the viewpoint of further improving low-temperature fixing properties and blocking resistance during storage, crystalline polyester may be used as a plasticizer.

<Colorant>
Examples of the coloring agent that can be contained in the toner include known organic pigments or oil dyes, carbon black, and magnetic materials.

More specifically, cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like.

Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, and the like.

Examples of the yellow colorant include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

Examples of the black colorant include carbon black, a magnetic material, and those toned to black using the yellow colorant, magenta colorant, and cyan colorant described above.

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

<Release agent>
If necessary, a release agent may be used to suppress the occurrence of hot offset during heat fixing of the toner. Examples of the mold release agent generally include low molecular weight polyolefins, silicone waxes, fatty acid amides, ester waxes, carnauba wax, and hydrocarbon waxes.

<Method for manufacturing toner particles>
Next, a procedure for manufacturing toner particles using the manufacturing method of the present invention will be described.

First, in the raw material mixing step, predetermined amounts of at least a binder resin, negative thermally expandable inorganic fine particles, and a colorant are weighed out, blended, and mixed as toner internal additives. 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, and the like 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, a Nauta mixer, and the like.

Furthermore, the toner raw materials blended and mixed above are melt-kneaded to melt the resins and disperse inorganic fine particles with negative thermal expansion, colorants, and the like. In the melt-kneading step, for example, a batch-type kneader such as a pressure kneader or a Banbury mixer, or a continuous-type kneader can be used. In recent years, single-screw or twin-screw extruders have become mainstream due to their superiority in continuous production, such as the KTK-type twin-screw extruder manufactured by Kobe Steel, and the TEM-type twin-screw extruder manufactured by Toshiba Machinery Co., Ltd. , a twin-screw extruder manufactured by K.C.K., a co-kneader manufactured by Buss, etc. are generally used.

Further, the colored resin composition obtained by melt-kneading the toner raw materials is rolled after melt-kneading with two rolls or the like, and is cooled through a cooling step of cooling with water or the like. At this time, it is thought that the inorganic fine particles having negative thermal expansion expand and cause minute cracks in the resin.

The cooled colored resin composition obtained above is then pulverized to a desired particle size in a pulverization step. In the pulverization process, first, the material is coarsely pulverized using a crusher, hammer mill, feather mill, etc. Furthermore, mechanical crushers such as Inomizer (manufactured by Hosokawa Micron), Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.), Super Rotor (manufactured by Nisshin Engineering), Turbo Mill (manufactured by Turbo Kogyo), or Counter Jet Mill (manufactured by Hosokawa Micron) ) is pulverized. In the pulverization step, the toner is pulverized in stages to a predetermined particle size.

Here, FIG. 1 schematically shows a mechanical pulverizer used for pulverization in Examples described later, and a predetermined amount of coarse powder is fed to a powder supply port (powder input port) 101 of the mechanical pulverizer. When the pulverized material (material to be pulverized) is input, the coarsely pulverized material is introduced into the pulverization processing chamber, which is a gap between the rotor 103 and the stator 104 . The particles are instantaneously crushed by the impact generated between the rotor, which rotates at high speed in the pulverization processing chamber, and the stator, which has many grooves on its surface. . Thereafter, the powder passes through the powder discharge port 106 and is discharged.

Further, it is preferable that the mechanical pulverizer is provided with a swirl chamber 102 communicating with the supply port 101, as shown in FIG. The coarsely pulverized material entering from the supply port 101 swirls along the wall of the swirl chamber 102, and as it continues to swirl, it is introduced into the pulverizing chamber according to the particle size of the coarsely pulverized material. In other words, it is thought that the rectifying effect is stronger than in a case without a swirl chamber, and particles can enter from the desired location more easily depending on the particle size.

On the other hand, FIG. 2 schematically shows a pulverization system incorporating another pulverizer (jet mill) used in the examples described later. In this pulverization system, coarsely pulverized material is introduced into a raw material feeder 233, and from the raw material feeder 233 is introduced into an air classifier 232 via a conveying pipe 234. The wind classifier 232 has a center core 240 and a separate core 241 inside a collector 238. In the wind classifier 232, the coarsely pulverized material is classified into finely pulverized material and coarse particles by secondary air introduced from the secondary air supply port 243. The classified finely ground material is discharged from the system via the discharge pipe 242. The classified coarse particles are introduced into the jet mill pulverizer 231 via the main body hopper section 239. In the pulverizer, coarse particles are supplied to a nozzle 235 into which compressed air is introduced, and the coarse particles are transported by high-speed compressed air and collided with a collision plate 236 in a crushing chamber 237 to be pulverized. The finely pulverized particles are introduced into the air classifier 232 via the conveying pipe 234 and classified again.

Methods for measuring various physical properties of toner and raw materials according to the present invention will be described below.

<Method for measuring weight average particle diameter (D4) of toner particles>
The weight average particle diameter (D4) of the toner particles was measured using a precise particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter) equipped with a 50 μm aperture tube using the pore electrical resistance method. Using the included dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting conditions and analyzing measured data, measurements were taken with 25,000 effective measurement channels, and the measured data was Analyze and calculate.

The electrolytic aqueous solution used in the measurement can be one in which special grade sodium chloride is dissolved in ion-exchanged water to have a concentration of about 1% by mass, such as "ISOTON II" (manufactured by Beckman Coulter).

Note that before performing measurement and analysis, the dedicated software is set as follows.

In the "Change standard measurement method (SOM) screen" of the dedicated software, set the total count in control mode to 50,000 particles, set the number of measurements to 1, and set the Kd value to "standard particle 10.0 μm" (Beckman Coulter). Set the value obtained using By pressing the threshold/noise level measurement button, the threshold and noise level are automatically set. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the aperture tube flush after measurement.

On 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) Approximately 200 ml of the above electrolyte aqueous solution is placed in a 250 ml round-bottom glass beaker exclusively for Multisizer 3, set on a sample stand, and stirred with a stirrer rod counterclockwise at 24 revolutions/second. Then, use the analysis software's ``aperture flush'' function to remove dirt and air bubbles from inside the aperture tube.
(2) Pour about 30 ml of the above electrolytic aqueous solution into a 100 ml glass flat-bottomed beaker, and add "Contaminon N" as a dispersant (precision measurement of pH 7 consisting of nonionic surfactant, anionic surfactant, and organic builder). Approximately 0.3 ml of a diluted solution prepared by diluting a 10% by mass aqueous solution of a neutral detergent for cleaning utensils (manufactured by Wako Pure Chemical Industries, Ltd.) by 3 times by mass with ion-exchanged water is added.
(3) Two oscillators with an oscillation frequency of 50 kHz are built in with their phases shifted by 180 degrees, and are installed in the water tank of an ultrasonic dispersion device "Ultrasonic Dispension System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W. A predetermined amount of ion-exchanged water is poured into the water tank, and approximately 2 ml of the contaminon N is added to the water tank.
(4) Set the beaker of (2) above in the beaker fixing hole of the ultrasonic disperser, and operate the ultrasonic disperser. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker is maximized.
(5) While the electrolytic aqueous solution in the beaker of (4) is irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolytic aqueous solution and dispersed. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. In addition, in the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10° C. or more and 40° C. or less.
(6) Using a pipette, drop the aqueous electrolyte solution of (5) in which toner is dispersed into the round bottom beaker of (1) placed in the sample stand, and adjust the measured concentration to approximately 5%. . Then, the measurement is continued until the number of particles to be measured reaches 50,000.
(7) Analyze the measurement data using the dedicated software attached to the device and calculate the weight average particle diameter (D4). 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 diameter (D4).

<Measurement method of outflow start temperature>
The start of outflow is measured using a constant force extrusion type capillary rheometer "Flow Characteristic Evaluation Device Flow Tester CFT-500D" (manufactured by Shimadzu Corporation) according to the manual attached to the device. In this device, a constant load is applied from the top of the measurement sample by a piston, the temperature of the measurement sample filled in the cylinder is raised and melted, and the molten measurement sample is pushed out from the die at the bottom of the cylinder. A flow curve can be obtained that shows the relationship between temperature and temperature.

In the present invention, the outflow start temperature described in the manual attached to "Flow Tester CFT-500D" is adopted. The sample, which has been softened by the temperature rise, passes through the thin tube section, reaching a temperature at which the piston begins to descend continuously.

The measurement sample was obtained by compression molding about 1.0 g of resin at about 10 MPa for about 60 seconds using a tablet molding and compression machine (for example, NT-100H, manufactured by NP Systems, Inc.) in an environment of 25 ° C. A cylinder with a diameter of about 8 mm is used.

The measurement conditions of CFT-500D are as follows.
Test mode: Heating method Starting temperature: 50℃
Achieved temperature: 200℃
Measurement interval: 1.0℃
Temperature increase rate: 4.0℃/min
Piston cross-sectional area: 1.000cm ²
Test load (piston load): 10.0kgf (0.9807MPa)
Preheating time: 300 seconds Die hole diameter: 1.0mm
Die length: 1.0mm

<Method for measuring the thermal expansion coefficient (linear expansion coefficient) of inorganic fine particles>
The thermal expansion coefficient of inorganic fine particles is calculated as follows.

The lattice constant of inorganic fine particles is measured using the following apparatus under the following conditions.
・Measuring device: MiniFlex600 (product name, manufactured by Rigaku Co., Ltd.)
Sample medium temperature attachment Hot plate/X-ray source: Cu-Kα ray/slit system: DS=SS=1.25°, RS=0.3mm
・Detector: Scintillation counter ・Scan method: 2θ-θ continuous scan ・Measurement range (2θ): 5-60°
・Step width (2θ): 0.02°
・Scan speed: 1°/min
・Measurement temperature: 30℃/50℃/70℃/100℃
Measured 10 minutes after reaching the target temperature

Based on the graph obtained and the inorganic material database, the lattice constants of the a-axis, b-axis, and c-axis at each temperature are determined, and the change in volumetric expansion is converted into linear expansion to determine the coefficient of thermal expansion.

<Method for measuring number average particle size of inorganic fine particles>
The number average particle size of the inorganic fine particles is the inorganic fine particles separated from the toner (if the toner contains pigments) taken with a Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Corporation). (mixture with pigment). The image shooting conditions for S-4800 are as follows.

(1) Sample Preparation A conductive paste is applied thinly to a sample stand (aluminum sample stand 15 mm x 6 mm), and inorganic fine particles separated from toner are sprayed onto it. Further, air is blown to remove excess inorganic fine particles from the sample stage and thoroughly dry it. Set the sample stage in the sample holder, and adjust the height of the sample stage to 36 mm using the sample height gauge.

(2) Setting S-4800 observation conditions Calculation of the number average particle diameter is performed using images obtained by backscattered electron image observation of the S-4800. Pour liquid nitrogen into the anti-contamination trap attached to the S-4800 housing until it overflows, and leave it for 30 minutes. Start up the "PC-SEM" of the S-4800 and perform flushing (cleaning of the FE chip, which is the electron source). Click the acceleration voltage display area of the control panel on the screen and press the [Flushing] button to open the flushing execution dialog. Check that the flushing strength is 2 and execute. Confirm that the emission current due to flushing is 20 to 40 μA. Insert the sample holder into the sample chamber of the S-4800 housing. Press [Origin] on the control panel to move the sample holder to the observation position.

Click the acceleration voltage display area to open the HV setting dialog, and set the acceleration voltage to [1.1 kV] and the emission current to [20 μA]. In the [Basic] tab of the operation panel, set the signal selection to [SE], select the SE detector to [Upper (U)] and [+BSE], and select [ in the selection box to the right of [+BSE]. L. A. 100] to set the mode for observation using a backscattered electron image. Similarly, in the [Basics] tab of the operation panel, set the probe current of the electron optical system condition block to [Normal], the focus mode to [UHR], and the WD to [4.5 mm]. Press the [ON] button on the acceleration voltage display section of the control panel to apply acceleration voltage.

(3) Focus adjustment Rotate the focus knob [COARSE] on the operation panel and adjust the aperture alignment when the image is in focus to a certain extent. Click [Align] on the control panel to display the alignment dialog and select [Beam]. Rotate the STIGMA/ALIGNMENT knobs (X, Y) on the operation panel to move the displayed beam to the center of the concentric circles. Next, select [Aperture] and turn the STIGMA/ALIGNMENT knobs (X, Y) one by one to stop or minimize the image movement. Close the aperture dialog and use autofocus to focus. Then, set the magnification to 80,000 (80k) times, adjust the focus using the focus knob and STIGMA/ALIGNMENT knob in the same way as above, and focus again using autofocus. Repeat this operation again to focus. If the angle of inclination of the observation surface is large, the accuracy of measuring the number average particle size tends to decrease, so when adjusting the focus, select a device that allows the entire observation surface to be brought into focus at the same time, so that there is as little surface inclination as possible. Select and analyze.

(4) Image saving Adjust the brightness in ABC mode, take a photo with a size of 640 x 480 pixels, and save it. The following analysis will be performed using this image file. In order to calculate the number average particle size by measuring the particle size of at least 500 inorganic fine particles, in order to obtain the required number of inorganic fine particles, images are taken at multiple locations so as not to photograph the same inorganic fine particle.

(5) Image analysis Measure the particle size of at least 500 inorganic fine particles to determine the number average particle size. In the present invention, image analysis software Image-Pro Plus ver. 5.0, the number average particle diameter is calculated by binarizing the image obtained by the method described above.

If the inorganic fine particles separated from the toner contain pigments, etc., perform elemental analysis using an energy dispersive X-ray spectrometer (EDS) and distinguish them based on particle size and shape, and exclude particles other than the inorganic fine particles to be measured. After that, perform the measurement.

<Method for measuring the content (volume %) of inorganic fine particles>
The number average particle diameter is calculated using the SEM image from which the above number average particle diameter was calculated. The ratio of the total area to the particle area is calculated, and the ratio is raised to the 3/2 power to measure as volume %.

[Configuration included in the embodiment of the present invention]
The disclosure of this embodiment includes the following configurations.
(Structure 1) A melt-kneading step of melt-kneading a resin composition containing a binder resin and inorganic fine particles to obtain a melt-kneaded product, and cooling and solidifying the melt-kneaded product, and then crushing and pulverizing the cooled-solidified product. A method for producing a toner, the method comprising: a pulverizing step to obtain a toner;
When the outflow start temperature of the binder resin is T1 (°C), the inorganic fine particles always have a coefficient of thermal expansion of -0.1×10 ^-6 (/K) or less in the temperature range of 30°C or more and T1°C or less. A method for producing a toner, characterized in that:
(Structure 2) The method for producing a toner according to Structure 1, wherein the inorganic fine particles are hexagonal zirconium phosphate particles.
(Structure 3) The method for producing a toner according to Structure 1 or 2, wherein the content of the inorganic fine particles is 0.3% by volume or more and 6.5% by volume or less with respect to the resin composition.
(Structure 4) The method for producing a toner according to Structure 1 or 2, wherein the content of the inorganic fine particles is 1.5% by volume or more and 4.5% by volume or less based on the resin composition.
(Structure 5) The method for producing a toner according to any one of Structures 1 to 4, wherein the inorganic fine particles have a number average particle diameter of 0.3 μm or more and 3.0 μm or less in the cooled and solidified product.
(Structure 6) The method for producing a toner according to any one of Structures 1 to 4, wherein the inorganic fine particles have a number average particle diameter of 0.5 μm or more and 3.0 μm or less in the cooled and solidified product.

In the following examples, parts are based on parts by weight.

<Production example of binder resin L>
・Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane: 72.0 parts (100.0 mol% based on the total number of moles of polyhydric alcohol)
・Terephthalic acid: 28.0 parts (96.0 mol% based on the total number of moles of polycarboxylic acids)
- Tin 2-ethylhexanoate (esterification catalyst): 0.5 part The above materials were weighed into a reaction tank equipped with a cooling tube, a stirrer, a nitrogen introduction tube, and a thermocouple. Next, after purging the inside of the flask with nitrogen gas, the temperature was gradually raised while stirring, and reaction was carried out for 4 hours while stirring at a temperature of 200°C.

Furthermore, the pressure inside the reaction tank was lowered to 8.3 kPa and maintained for 1 hour, then cooled to 180° C. and returned to atmospheric pressure.
- Trimellitic anhydride: 3 parts (4.0 mol% based on the total number of moles of polycarboxylic acids)
・Tert-butylcatechol (polymerization inhibitor): 0.1 part After that, the above materials were added, the pressure inside the reaction tank was lowered to 8.3 kPa, and the reaction was carried out for 1 hour while maintaining the temperature at 180°C, and ASTM D36- After confirming that the softening point measured in accordance with No. 86 had reached 90° C., the temperature was lowered to stop the reaction, and a binder resin L (weight average molecular weight: 5100) was obtained.

<Production example of binder resin H>
・Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane: 72.3 parts (100.0 mol% based on the total number of moles of polyhydric alcohol)
・Terephthalic acid: 18.3 parts (65.0 mol% based on the total number of moles of polycarboxylic acids)
・Fumaric acid: 2.9 parts (0.03 mol; 15.0 mol% based on the total number of moles of polyhydric carboxylic acids)
- Tin 2-ethylhexanoate (esterification catalyst): 0.5 part The above materials were weighed into a reaction tank equipped with a cooling tube, a stirrer, a nitrogen introduction tube, and a thermocouple. Next, after purging the inside of the flask with nitrogen gas, the temperature was gradually raised while stirring, and the mixture was reacted for 2 hours while stirring at a temperature of 200°C.

Furthermore, the pressure inside the reaction tank was lowered to 8.3 kPa and maintained for 1 hour, then cooled to 180°C and returned to atmospheric pressure.
- Trimellitic anhydride: 6.5 parts (20.0 mol% based on the total number of moles of polycarboxylic acids)
・Tert-butylcatechol (polymerization inhibitor): 0.1 part After that, the above materials were added, the pressure inside the reaction tank was lowered to 8.3 kPa, and the reaction was carried out for 15 hours while maintaining the temperature at 160°C, and ASTM D36- After confirming that the softening point measured according to No. 86 had reached 137° C., the temperature was lowered to stop the reaction, and binder resin H (weight average molecular weight 77,100) was obtained.

<Inorganic fine particles 1 to 9>
Inorganic fine particles 1 used hexagonal zirconium phosphate particles (Ultair WH2; manufactured by Toagosei Co., Ltd.), and inorganic fine particles 2 to 6 used Ultair WH2 whose particle size was changed by classifying it using an air classifier. there was.

As the inorganic fine particles 7, calcium carbonate particles (light calcium carbonate; manufactured by Maruo Calcium Co., Ltd.) were used. As the inorganic fine particles 8, silica particles (Silfil NHM-3N; manufactured by Tokuyama Corporation) were used. As the inorganic fine particles 9, layered zirconium phosphate particles (layered zirconium phosphate; manufactured by Aldrich) were used.

The physical properties of inorganic fine particles 1 to 9 are shown in Table 1. T1 when determining the coefficient of thermal expansion in Table 1 is 85.5° C. for the binder resin (binder resin L+binder resin H) in Example 1, etc. described below. Furthermore, the thermal expansion coefficients of the inorganic fine particles 1 to 6 had the maximum value (-2×10 ^-6 (/K)) in the range of 30° C. to 85.5° C. in the table. In addition, the thermal expansion coefficients of inorganic fine particles 7 to 9 are the values shown in the table (10×10 ^-6 (/K) and 0.55×10 ^-6 (/K), respectively, in the range of 30°C to 85.5°C. ), 0.8×10 ⁻⁶ (/K)) was the minimum value.

[Example 1]
<Manufacture of toner 1>
(melt kneading process/coarse grinding process)
- Binder resin L 80 parts - Binder resin H 20 parts - Fischer-Tropsch wax (hydrocarbon wax, maximum endothermic peak temperature 90°C) 8 parts - C.I. I. Pigment Blue 15:3 7 parts / Inorganic fine particles 1 10 parts The above materials were mixed using a Henschel mixer (model FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 20 s ^-1 and a rotation time of 5 min. The mixture was kneaded using a shaft kneader (PCM-30 model, 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 material was directly measured using a handy type thermometer HA-200E manufactured by Anritsu Keiki Co., Ltd.

The obtained kneaded product was cooled to 30° C. in 1 minute, and coarsely ground using a pin mill to a volume average particle size of 100 μm or less to obtain a coarsely ground product.

(Fine grinding process)
As a configuration of a pulverizer for pulverizing the above-mentioned coarsely crushed material, a mechanical pulverizer (Turbo Mill T250-CRS-rotor shape RS type manufactured by Turbo Kogyo Co., Ltd.) was modified and the apparatus shown in FIG. 1 (apparatus 1) was used. With the configuration of device 1, the feed rate of crushed material is 20 kg/h, the rotation speed of the rotor is 170 m/s, the gap between the rotor and stator is 1.0 mm, the cold air temperature is -10°C, and the cold air flow is 8 m ³ /min. Toner 1 was produced.

[Example 2]
<Manufacture of toner 1'>
(Fine grinding process)
As the configuration of the pulverizer for pulverizing the coarsely crushed material in Example 1, a jet mill pulverizer manufactured by Hosokawa Micron Corporation (PICOJET pulverizer; device 2) shown in FIG. 2 was used. Toner 1' was manufactured by operating apparatus 2 with the configuration of apparatus 2 at an accelerated injection speed of 8.8 m/s of the material to be crushed to the collision plate in the crushing chamber.

[Examples 3 to 13, Comparative Examples 1 to 3]
Crushed products were obtained in the same manner as in Example 1, except that inorganic fine particles 1 were changed to the inorganic fine particles and amounts shown in Table 2, and toners 2 to 16 were obtained using the same apparatus 1 and operating conditions as in Example 1. .

[evaluation]
D4, which is the particle size distribution of the obtained toners 1 to 16, was measured, and D4 was evaluated based on the following evaluation criteria. The evaluation results are shown in Table 3.

<Evaluation criteria>
A: D4 is less than 6.00μm (very excellent)
B: D4 is 6.00 μm or more and less than 6.20 μm (excellent)
C: D4 is 6.20 μm or more and less than 6.40 μm (good)
D: D4 is 6.40 μm or more and less than 6.60 μm (this is a level that poses no problem in the present invention)
E: D4 is 6.60 μm or more (unacceptable according to the present invention)

In Comparative Example 1, calcium carbonate fine particles were added. The effect of the filler improves the crushability somewhat, but the effect of cracking due to negative thermal expansion is not achieved. Therefore, it is presumed that the present invention resulted in unacceptable grindability and increased particle size.

In Comparative Example 2, silica was added. Similar to Comparative Example 1, the effect of the filler improved the crushability somewhat, but the effect of cracking due to negative thermal expansion was not obtained. Therefore, it is presumed that the present invention resulted in unacceptable grindability and increased particle size.

In Comparative Example 3, layered zirconium phosphate was added. Similar to Comparative Example 1, the effect of the filler improved the crushability somewhat, but the effect of cracking due to negative thermal expansion was not achieved. Therefore, it is presumed that the present invention resulted in unacceptable grindability and increased particle size.

In Comparative Example 4, no filler was added. It is presumed that the effect of the filler was not obtained, and the crushability was unacceptable in the present invention, and the particle size also increased.

101: Supply port, 102: Vortex chamber, 103: Rotor, 104: Stator, 105: Rear chamber, 106: Discharge port, 107: Rotating shaft, 108: Cold air generator, 109: Cold water supply port, 110: Cold water outlet, 231: Grinding machine, 232: Classifier, 233: Raw material supply machine, 234: Conveying pipe, 235: Nozzle, 236: Collision plate, 237: Grinding chamber, 238: Collector, 239: Main body hopper section, 240 : Center core, 241: Separate core, 242: Discharge pipe, 243: Secondary air supply port

Claims (6)

A melt-kneading step in which a resin composition containing a binder resin and inorganic fine particles is melt-kneaded to obtain a melt-kneaded product, and a pulverization step in which the melt-kneaded product is cooled and solidified, and then the cooled and solidified product is pulverized to obtain a pulverized product. A method for producing a toner, comprising the steps of:
When the outflow start temperature of the binder resin is T1 (°C), the inorganic fine particles always have a coefficient of thermal expansion of -0.1×10 ^-6 (/K) or less in the temperature range of 30°C or more and T1°C or less. A method for producing a toner, characterized in that: The method for producing a toner according to claim 1, wherein the inorganic fine particles are hexagonal zirconium phosphate particles. 3. The method for producing a toner according to claim 1, wherein the content of the inorganic fine particles is 0.3% by volume or more and 6.5% by volume or less based on the resin composition. 3. The method for producing a toner according to claim 1, wherein the content of the inorganic fine particles is 1.5% by volume or more and 4.5% by volume or less based on the resin composition. 3. The method for producing a toner according to claim 1, wherein the inorganic fine particles have a number average particle diameter of 0.3 μm or more and 3.0 μm or less in the cooled and solidified product. 3. The method for producing a toner according to claim 1, wherein the inorganic fine particles have a number average particle diameter of 0.5 μm or more and 3.0 μm or less in the cooled and solidified product.

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