JP2021144102A - Method for manufacturing toner - Google Patents

Abstract

To provide a method for manufacturing a toner having a sharp particle size distribution.SOLUTION: A method for manufacturing a toner comprises: a mixing step of mixing inorganic fine particles with toner particles to obtain a mixture; and a heating step of heating the mixture by the hot air to obtain the heated toner particles. The toner particles have a weight average particle diameter of 3.0 μm or more and 5.0 μm or less; the ratio of particles having a particle size of 2.0 μm or less is 0.2 vol.% or more and 0.5 vol.% or less; when setting the average circularity of the toner particles to C1 and the average circularity of the heated toner particles to C2, C1 and C2 satisfy the following formula (1), 0.010≤C2-C1 the formula (1); and when setting the weight average particle diameter of the toner particles to D (μm) and the number average particle size of the primary particles of the inorganic fine particles to d (μm), d/D satisfies the following formula (2), 0.015≤d/D≤0.075 the formula (2).SELECTED DRAWING: None

Description

The present invention relates to a toner manufacturing method used in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and a toner jet method.

In recent years, electrophotographic full-color copiers have become widespread and have begun to be applied to the printing market. In the printing market, high speed, high image quality, and high productivity are required while supporting a wide range of media (paper types). In order to achieve high developability and transferability, a thermospherical treatment of toner particles is effective (Patent Document 1). This is because the large particle size fine particles adhere to the surface of the toner particles by heat treatment, so that a spacer effect is exhibited between the toners.
Further, in toner, the image quality is being improved by reducing the particle size. There are merits such as improvement in reproducibility of fine lines by reducing the particle size. Since the adhesive force is increased by reducing the particle size, the thermal spheroidizing treatment is becoming more important, such as the fixing of the external additive such as the spacer effect by the external additive and the increase in circularity. However, when the thermal spheroidizing treatment of the toner having a small particle size is performed, there is a tendency that adverse effects such as an increase in the particle size and a broadening of the distribution due to the coalescence of the toner particles become large. There is room for further improvement in that it is necessary to suppress the increase in particle size and the broadening due to the coalescence of toner particles in order to achieve thermal spheroidization during the production of small particle size toner.

Japanese Unexamined Patent Publication No. 2013-20244

An object of the present invention is to solve the above-mentioned problems, suppress an increase in particle size during the thermal spheroidization treatment, and provide a toner having a sharp particle size distribution by selectively coalescing the particles. be.

The present invention is a method for producing a toner, which comprises a mixing step of mixing inorganic fine particles with toner particles to obtain a mixture, and a heat treatment step of heat-treating the mixture with hot air to obtain toner particles after the heat treatment.
The toner particles have a weight average particle size of 3.0 μm or more and 5.0 μm or less, and the proportion of particles having a particle size of 2.0 μm or less is 0.2% by volume or more and 0.5% by volume or less.
When the average circularity of the toner particles is C1 and the average circularity of the toner particles after the heat treatment is C2, the C1 and the C2 satisfy the following formula (1).
0.010 ≤ C2-C1 equation (1)
When the weight average particle size of the toner particles is D (μm) and the number average particle size of the primary particles of the inorganic fine particles is d (μm), d / D satisfies the following formula (2). Regarding the method of manufacturing toner.
0.015 ≤ d / D ≤ 0.075 Equation (2)

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a toner manufacturing method that suppresses an increase in particle size during a thermal spheroidizing treatment and sharpens the particle size distribution of a small particle size toner.

It is a figure which shows an example of the thermal spheroidizing apparatus preferably used for this invention.

The toner particles according to the present invention have a weight average particle size of 3.0 μm or more and 5.0 μm or less, and undergo a thermal spheroidization treatment to become a small particle size toner. Such a small particle size toner has merits such as improved reproducibility of fine wires.

However, when the above-mentioned small particle size toner is subjected to the thermal spheroidization treatment, the toner particles tend to coalesce easily, and adverse effects such as an increase in particle size and a broadening of the distribution tend to increase. As a result of studies to improve this point by the present inventors, by devising the ratio of the toner particle size and the particle size of the large particle size external additive, the small particle size toner can be made into a thermal sphere without the above-mentioned adverse effects. I succeeded in doing it.

Although the mechanism by which the small particle size toner can be formed into a thermal sphere without any harmful effect in the present invention has not been determined at present, the present inventors assume as follows.

In the present invention, the weight average particle size D (μm) of the toner particles and the number average particle size d (μm) of the primary particles of the inorganic fine particles are set to 0.015 ≦ d / D ≦ 0.075 equation (2).
It is important to be in the range of. When each particle size is in this range, it is considered that the large particle size external additive is too large for the toner particles, so that it is difficult to adhere to the surface of the toner particles. In particular, this effect is likely to be exhibited at the particle size on the fine particle side, and the external additive is particularly difficult to adhere to the toner particles on the fine particle side. As a result, it is presumed that the fine particles of the toner particles are selectively united during the thermal spheroidization treatment, and only the fine particles can be reduced. It is speculated that the selective reduction of only the fine particles led to the sharpening of the particle size distribution. However, if the amount of fine particles is too large, it will be difficult to reduce the amount of fine particles by coalescence, or the particle size will become too large as a result of coalescence. It is necessary that the proportion of particles having a particle size of 2.0 μm or less is 0.2% by volume or more and 0.5% by volume or less.

<Manufacturing method of toner particles>
Next, a procedure for producing toner particles by the production method of the present invention will be described.

First, in the raw material mixing step, at least a binder resin and a colorant are weighed and mixed in a predetermined amount as the toner internalizing agent and mixed. If necessary, a mold release agent that suppresses the occurrence of hot offset during heating and fixing of the toner, a dispersant that disperses the mold release agent, a charge control agent, and the like may be mixed. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauter mixer and the like.

Further, the toner raw materials blended and mixed as described above are melt-kneaded to melt the resins and disperse the colorants and the like therein. In the melt-kneading step, for example, a batch-type kneader such as a pressure kneader or a Bambary mixer, or a continuous-type kneader can be used. In recent years, single-screw or twin-screw extruders have become the mainstream because of their superiority such as continuous production. For example, KTK type twin-screw extruder manufactured by Kobe Steel Co., Ltd. and 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 material is melt-kneaded, rolled by two rolls or the like, and cooled through a cooling step of cooling by water cooling or the like.

The cooled product of the colored resin composition obtained above is then pulverized to a desired particle size in a pulverization step. In the crushing step, first, coarse crushing is performed with a crusher, a hammer mill, a feather mill or the like. Further, it is finely pulverized by a mechanical crusher such as an innomizer (manufactured by Hosokawa Micron Co., Ltd.), a cryptron (manufactured by Kawasaki Heavy Industries, Ltd.), a super rotor (manufactured by Nisshin Engineering Co., Ltd.), and a turbo mill (manufactured by Turbo Industries Co., Ltd.). In the pulverization step, the toner is pulverized to a predetermined toner particle size step by step in this way. After pulverization, classification is performed as necessary to obtain toner particles.

<Mixing process>
In the mixing step, the toner particles and the inorganic fine particles are mixed. As the mixing device, a high-speed stirrer for applying a shearing force to powder such as Henshell mixer, Mechanohybrid (manufactured by Nippon Coke Co., Ltd.), Supermixer, Nobilta (manufactured by Hosokawa Micron Co., Ltd.) can be used.

In the particle mixture that has undergone the mixing step, the coverage of the inorganic fine particles on the surface of the toner particles is preferably in the following range. It is preferable that the coverage of the inorganic fine particles on the toner particles having a particle size of less than 2.0 μm is 10% or less, and the coverage of the inorganic fine particles on the toner particles having a particle size of 2.0 μm or more is 30% or more. These coverage can be adjusted by the number of revolutions and the mixing time. In order to increase the coverage, methods such as increasing the number of revolutions and extending the mixing time are preferable.

<Heat treatment process>
Subsequently, the obtained particle mixture is spheroidized in a heat treatment step. For the heat treatment, for example, a heat treatment apparatus as shown in FIG. 1 can be used.

Hereinafter, the heat treatment using the heat treatment apparatus shown in FIG. 1 will be described.

The mixture (mixture of toner particles and inorganic fine particles) quantitatively supplied by the raw material quantitative supply means 1 is supplied to the introduction pipe 3 installed on the vertical line of the raw material supply means by the compressed gas prepared by the compressed gas adjusting means 2. Be guided. The mixture that has passed through the introduction pipe is uniformly dispersed by the conical protruding member 4 provided in the central portion of the raw material supply means, and is guided to the supply pipe 5 in eight directions that spread radially to perform heat treatment. Guided to.

At this time, the flow of the mixture supplied to the treatment chamber is regulated by the regulating means 9 for regulating the flow of the mixture provided in the treatment chamber. Therefore, the mixture supplied to the treatment chamber is heat-treated while swirling in the treatment chamber, 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 by spirally swirling the hot air into the processing chamber by the swirling member 13 for swirling the hot air. Will be done. As its configuration, the swirling member 13 for swirling the hot air has a plurality of blades, and the swirling of the hot air can be controlled by the number and angles thereof. The temperature at the outlet of the hot air supply means 7 is preferably 100 ° C. or higher and 300 ° C. or lower, and more preferably 130 ° C. or higher and 170 ° C. or lower. When the temperature at the outlet of the hot air supply means is within the above range, it is possible to uniformly spheroidize the mixture while preventing fusion and coalescence of toner particles due to overheating of the mixture. The average circularity at this time is preferably 0.955 or more and 0.980 or less. Hot air is supplied from the hot air supply means outlet 11.

Further, the heat-treated particles are cooled by the cold air supplied from the cold air supply means 8. The temperature supplied from the cold air supply means 8 is preferably −20 ° C. to + 30 ° C. When the temperature of the cold air is within the above range, the heat-treated particles can be efficiently cooled, and the fusion and excessive coalescence of the particles are prevented without interfering with the uniform spheroidizing treatment of the mixture. can do. The absolute water content of the cold air ^{is preferably 0.5 g / m 3} or more and 15.0 g / m ³ or less.

Next, the cooled heat-treated toner particles are recovered by the recovery means 10 at the lower end of the processing chamber. A blower (not shown) is provided at the tip of the collecting means, and the suction is conveyed by the blower (not shown).

Further, the powder particle supply port 14 is provided so that the swirling direction of the supplied mixture and the swirling direction of the hot air are in the same direction, and the recovery means 10 of the surface treatment device is a swirling powder particle. It is provided on the outer peripheral portion of the processing chamber so as to maintain the turning direction. Further, the cold air supplied from the cold air supply means 8 is configured to be supplied horizontally and tangentially from the outer peripheral portion of the apparatus to the peripheral surface of the processing chamber. The swirling direction of the mixture supplied from the powder supply port, the swirling direction of the cold air supplied from the cold air supply means, and the swirling direction of the hot air supplied from the hot air supply means are all in the same direction. Therefore, turbulent flow does not occur in the processing chamber, the swirling flow in the device is strengthened, a strong centrifugal force is applied to the mixture, and the dispersibility is further improved. Particles can be obtained.

In the present invention, when the average circularity of the toner particles is C1 and the average circularity of the toner particles after the heat treatment is C2, it is necessary that the C1 and the C2 satisfy the following formula (1).
0.010 ≤ C2-C1 equation (1)

The range of change in average circularity reflects the degree of heat treatment. When the treatment is performed so that the change width of the average circularity satisfies the equation (1), the coalescence of the fine particles proceeds sufficiently, and the reduction of the fine particles is sufficiently achieved. As a result, a sharp particle size distribution is achieved in the small particle size toner.

<Raw material for toner particles>
Next, the raw materials of the toner particles containing at least the binder resin and the colorant used in the present invention will be described.

<Bundling resin>
As the binder resin used for the toner used for electrophotographic, a general resin can be used, and a polyester resin, a styrene-acrylic acid ester copolymer, a polyolefin resin, a vinyl resin, a fluororesin, and a phenol resin can be used. , Silicone resin, epoxy resin and the like can be exemplified. Among these, amorphous polyester resin is used from the viewpoint of improving low temperature fixability, and it is known that low molecular weight polyester and high molecular weight polyester are used in combination from the viewpoint of achieving both low temperature fixability and hot offset resistance. ing. In addition, crystalline polyester may be used as a plasticizer from the viewpoint of further improving low-temperature fixability and blocking resistance during storage.

<Colorant>
Examples of the colorant that can be contained in the toner include the following.

Examples of the colorant include known organic pigments or oil dyes, carbon black, magnetic substances and the like.

Examples of the cyanide colorant include a copper phthalocyanine compound and its derivative, an anthraquinone compound, and a basic dye lake compound. 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, or a color toned black using the yellow colorant, magenta colorant, and cyan colorant.

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

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

<Inorganic fine particles mixed with toner particles>
As the inorganic fine particles, inorganic fine particles such as silica fine particles, titanium oxide fine particles, and aluminum oxide fine particles are preferable. These are preferably hydrophobized with hydrophobizing agents such as silane compounds, silicone oils or mixtures thereof.

As for the inorganic fine particles, the number average particle size d of the primary particles is preferably 50 nm or more and 350 nm or less. When it is in this range, it is possible to achieve both improvement of fluidity and stabilization of durability.

The inorganic fine particles are preferably used in an amount of 3.0 parts by mass or more and 7.0 parts by mass or less with respect to 100 parts by mass of the toner particles.

The methods for measuring various physical properties will be described below.

<Measuring method of weight average particle size (D4) of toner particles>
The weight average particle size (D4) of the toner particles is measured with a precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter) equipped with a 50 μm aperture tube by the pore electric resistance method. Using the attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting conditions and analyzing measurement data, the measurement data is measured with 25,000 effective measurement channels. Is analyzed and calculated.

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

Before performing measurement and analysis, the dedicated software is set as follows.

In the "Standard measurement method (SOM) change screen" of the dedicated software, the total count number in the control mode is set to 50,000 particles, the number of measurements is one, and the Kd value is "Standard particle 10.0 μm" (Beckman Coulter). Set the value obtained using (manufactured by the company). 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, and the electrolyte to ISOTON II, and check the flush of the aperture tube after measurement.

In the "pulse to particle size conversion setting screen" of the dedicated software, the bin spacing is set to logarithmic particle size, the particle size bin is set to 256 particle size bins, and the particle size range is set to 1 μm or more and 30 μm or less.

The specific measurement method is as follows.
(1) Approximately 200 ml of the electrolytic aqueous solution is placed in a glass 250 ml round bottom beaker dedicated to Multisizer 3 and set on a sample stand, and the stirrer rod is stirred counterclockwise at 24 rpm. Then, the dirt and air bubbles in the aperture tube are removed by the "aperture flash" function of the analysis software.
(2) Approximately 30 ml of the electrolytic aqueous solution is placed in a 100 ml flat-bottomed beaker made of glass, and "Contaminone N" (nonionic surfactant, anionic surfactant, and organic builder) as a dispersant is used as a dispersant for precise measurement of pH 7. Add about 0.3 ml of a diluted solution obtained by diluting a 10% by mass aqueous solution of a neutral detergent for cleaning a vessel, manufactured by Wako Pure Chemical Industries, Ltd.) with ion-exchanged water 3 times by mass.
(3) Two oscillators with an oscillation frequency of 50 kHz are built in with the phase shifted by 180 degrees, and are installed in the water tank of the ultrasonic disperser "Ultrasonic Dispension System Tetora 150" (manufactured by Nikkaki Bios) with an electrical output of 120 W. A predetermined amount of ion-exchanged water is added, and about 2 ml of the Contaminone N is added into the water tank.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker is maximized.
(5) With the electrolytic aqueous solution in the beaker of (4) being 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 processing is continued for another 60 seconds. In ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10 ° C. or higher and 40 ° C. or lower.
(6) Using a pipette, the aqueous electrolyte solution of (5) in which toner is dispersed is dropped onto the round-bottom beaker of (1) installed in the sample stand, and the measured concentration is adjusted to about 5%. .. Then, the measurement is performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed by the dedicated software attached to the device, and the weight average particle size (D4) is calculated. The "average diameter" of the analysis / volume statistical value (arithmetic mean) screen when the graph / volume% is set by the dedicated software is the weight average particle diameter (D4).

<Measuring method of number average particle size (D1) of toner particles>
In step (7) of the method for measuring the weight average particle size (D4) of toner particles, the "average diameter" of the analysis / number statistical value (arithmetic mean) screen when graph / number% is set with the dedicated software The number average particle size (D1).

<Measuring method of average circularity>
The average circularity is measured by the 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 impure solids and the like have been removed in advance is placed in a glass container. Among them, as a dispersant, "Contaminone N" (a 10% by mass aqueous solution of a neutral detergent for cleaning a precision measuring instrument with a pH of 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd. ) Is diluted about 3 times by mass with ion-exchanged water, and about 0.2 ml of the diluted solution is added. Further, about 0.02 g of the measurement sample is added, and the dispersion treatment is performed for 2 minutes using an ultrasonic disperser to prepare a dispersion liquid for measurement. At that time, the dispersion liquid is appropriately cooled so that the temperature is 10 ° C. or higher and 40 ° C. or lower. As the ultrasonic disperser, a desktop ultrasonic cleaner disperser (“VS-150” (manufactured by Vervocreer)) with an oscillation frequency of 50 kHz and an electrical output of 150 W is used, and a predetermined amount of ions are contained in the water tank. Exchange water is added, and about 2 ml of the Contaminone N is added into the water tank.

For the measurement, the flow type particle image analyzer equipped with a standard objective lens (10 times) was used, and a particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion liquid adjusted according to the above procedure is introduced into the flow type particle image analyzer, and 3000 toner particles are measured in the total count mode in the HPF measurement mode. Then, the binarization threshold value at the time of particle analysis is set to 85%, the diameter of the analyzed particle is limited to 1.985 μm or more and less than 39.69 μm, and the average circularity of the toner particles is obtained.

In the measurement, automatic focus adjustment is performed using standard latex particles (“RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A” manufactured by Duke Scientific) diluted with ion-exchanged water before the start of the measurement. After that, it is preferable to perform focus adjustment every 2 hours from the start of measurement.

In the examples, a flow-type particle image analyzer for which a calibration work was performed by Sysmex Corporation and a calibration certificate issued by Sysmex Corporation was issued was used. The measurement was performed under the measurement and analysis conditions when the calibration certificate was obtained, except that the particle size of the analysis particle was limited to 1.985 μm or more and less than 39.69 μm in equivalent circle diameter.

<particle size of inorganic fine particles>
The number average particle size of the external additive is measured using a transmission electron microscope (TEM) "JEM2800" (manufactured by JEOL Ltd.).

First, a measurement sample is prepared. To about 5 mg of the external additive, 1 ml of isopropanol is added and dispersed with an ultrasonic disperser (ultrasonic cleaner) for 5 minutes. Next, one drop of the above dispersion was added to a microgrid (150 mesh) with a support film for TEM, and the mixture was dried to prepare a measurement sample.

Next, a transmission electron microscope (TEM) is used to acquire an image under the condition of an acceleration voltage of 200 kV at a magnification (for example, 200,000 to 1,000,000 times) that allows the external additive in the visual field to be sufficiently length-measured. , The major axis of the primary particles of 100 external additives is randomly measured to obtain the number average particle size. The particle size may be measured manually or by using a measuring tool.

<Calculation of coverage>
The coverage is based on the image analysis software Image-Pro, which is an image of the surface of toner particles with inorganic fine particles attached to the surface, taken with a Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Corporation). Plus ver. Calculated by analyzing with 5.0 (Nippon Roper Co., Ltd.). The image capturing conditions of S-4800 are as follows.

(1) Sample preparation A thin layer of conductive paste is applied to a sample table (aluminum sample table 15 mm × 6 mm), and a measurement sample is sprayed on the sample table. Further air blow to remove excess measurement sample from the sample table and allow it to dry sufficiently. Set the sample table in the sample holder and adjust the sample table height to 36 mm with the sample height gauge.

(2) Setting of observation conditions for S-4800 The coverage X is calculated using the image obtained by observing the reflected electron image of S-4800. Since the backscattered electron image has less charge-up of the inorganic fine particles than the secondary electron image, the coverage X can be measured with high accuracy.

Inject liquid nitrogen into the anti-contamination trap attached to the mirror body of S-4800 until it overflows, and leave it for 30 minutes. Start up "PC-SEM" of S-4800 and perform flushing (cleaning of FE chip which is an electron source). Click the acceleration voltage display part of the control panel on the screen and press the [Flushing] button to open the flushing execution dialog. Confirm that the flushing intensity 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 mirror. Press [Origin] on the control panel to move the sample holder to the observation position.

Click the acceleration voltage display to open the HV setting dialog, and set the acceleration voltage to [0.8 kV] and the emission current to [20 μA]. In the [Basic] tab of the operation panel, set the signal selection to [SE], select [Up (U)] and [+ BSE] for the SE detector, and select [+ BSE] in the selection box to the right of [+ BSE]. L. A. 100] is selected to set the mode for observing with a reflected electron image. Similarly, in the [Basic] tab of the operation panel, set the probe current of the electro-optical system condition block to [Normal], the focus mode to [UHR], and the WD to [3.0 mm]. Press the [ON] button on the acceleration voltage display of the control panel to apply the acceleration voltage.

(3) Focus adjustment Rotate the focus knob [COARSE] on the operation panel and adjust the aperture alignment when the focus is reached to some 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 the movement of the image or adjust it to the minimum movement. Close the aperture dialog and focus with autofocus. After that, the magnification is set to 50,000 (50k) times, the focus is adjusted using the focus knob and the STIGMA / ALIGNMENT knob in the same manner as above, and the focus is adjusted again by autofocus. Repeat this operation again to focus. Here, if the inclination angle of the observation surface is large, the measurement accuracy of the coverage tends to be low, so by selecting the one that focuses on the entire observation surface at the same time when adjusting the focus, select the one with the least inclination of the surface. And analyze.

(4) Image saving Perform brightness adjustment in ABC mode, take a picture with a size of 640 x 480 pixels, and save it. The following analysis is performed using this image file. One photograph is taken for each mother particle to which the particles are attached, and an image is obtained for at least 30 mother particles.

(5) Image analysis Using the following analysis software, the coverage X is calculated by binarizing the image obtained by the above method. At this time, the above screen is divided into 12 squares and each is analyzed. Image analysis software Image-Pro Plus ver. The analysis conditions for 5.0 are as follows.

Soft Image-ProPlus 5.1J
Select "Measurement"->"Count / Size"-"Options" on the toolbar and set the binarization conditions. Select 8 concatenations in the object extraction options and set the smoothing to 0. In addition, pre-sort, fill holes, do not select envelopes, and set "exclude borders" to "none". Select "Measurement item" from "Measurement" on the toolbar, and enter 2 to 107 in the area selection range.

The coverage is calculated by enclosing a square area. At this time, the area (C) of the area is set to 24,000 to 26000 pixels. "Treatment" -The value is automatically binarized by binarization, and the total area (D) of the area without the inorganic fine particles to be measured is calculated.

From the area C of the square area and the total area D of the area without the inorganic fine particles to be measured, the coverage can be obtained by the following formula.
Coverage (%) = 100- (D / C x 100)

The average value of all the obtained data is used as the coverage in the present invention.

<Production example of amorphous polyester resin L>
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane: 72.0 parts by mass (0.20 mol; 100.0 mol% based on the total number of moles of polyhydric alcohol)
-Terephthalic acid: 28.0 parts by mass (0.17 mol; 100.0 mol% with respect to the total number of moles of polyvalent carboxylic acid)
-Tin 2-ethylhexanoate (esterification catalyst): 0.5 parts by mass The above materials were weighed in a cooling tube, a stirrer, a nitrogen introduction tube, and a reaction vessel equipped with a thermocouple. Next, the inside of the flask was replaced with nitrogen gas, the temperature was gradually raised while stirring, and the reaction was carried out for 4 hours while stirring at a temperature of 200 ° C.

Further, the pressure in the reaction vessel was lowered to 8.3 kPa, maintained for 1 hour, cooled to 180 ° C., and returned to atmospheric pressure.

Trimellitic anhydride: 3 parts by mass (0.01 mol; 4.0 mol% based on the total number of moles of polyvalent carboxylic acid)
-Tert-Butylcatechol (polymerization inhibitor): 0.1 parts by mass Then, the above material was added, the pressure in the reaction vessel was lowered to 8.3 kPa, and the reaction was carried out for 1 hour while maintaining the temperature at 180 ° C., ASTM D36. After confirming that the softening point measured according to −86 reached 90 ° C., the temperature was lowered 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 (0.20 mol; 100.0 mol% based on the total number of moles of polyhydric alcohol)
-Terephthalic acid: 18.3 parts by mass (0.11 mol; 65.0 mol% with respect to the total number of moles of polyvalent carboxylic acid)
Fumaric acid: 2.9 parts by mass (0.03 mol; 15.0 mol% based on the total number of moles of polyvalent carboxylic acid)
-Tin 2-ethylhexanoate (esterification catalyst): 0.5 parts by mass The above materials were weighed in a cooling tube, a stirrer, a nitrogen introduction tube, and a reaction vessel equipped with a thermocouple. Next, the inside of the flask was replaced with nitrogen gas, the temperature was gradually raised while stirring, and the reaction was carried out for 2 hours while stirring at a temperature of 200 ° C.

Further, the pressure in the reaction vessel was lowered to 8.3 kPa, maintained for 1 hour, cooled to 180, and returned to atmospheric pressure.

Trimellitic anhydride: 6.5 parts by mass (0.03 mol; 20.0 mol% based on the total number of moles of polyvalent carboxylic acid)
-Tert-Butylcatechol (polymerization inhibitor): 0.1 parts by mass Then, the above material was added, the pressure in the reaction vessel was lowered to 8.3 kPa, and the reaction was carried out for 15 hours while maintaining the temperature at 160 ° C., ASTM D36. After confirming that the softening point measured according to −86 reached 137 ° C., the temperature was lowered 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 mol; 100.0 mol% based on the total number of moles of polyhydric alcohol)
Dodecanedioic acid: 65.5 parts by mass (0.28 mol; 100.0 mol% based on the total number of moles of polyvalent carboxylic acid)
-Tin 2-ethylhexanoate: 0.5 parts by mass The above materials were weighed in a cooling tube, a stirrer, a nitrogen introduction tube, and a reaction vessel equipped with a thermocouple. After replacing the inside of the flask with nitrogen gas, the temperature was gradually raised while stirring, and the reaction was carried out for 3 hours while stirring at a temperature of 140 ° C.

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

Further, after gradually releasing the pressure in the reaction vessel to return to normal pressure, 7.0 parts by mass of stearic acid was added to 100.0 parts by mass of the raw material monomer, and the reaction was carried out at 200 ° C. for 2 hours under normal pressure. I let you.

Then, the inside of the reaction vessel was reduced to 5 kPa or less and reacted at 200 ° C. for 3 hours to obtain a crystalline polyester resin.

[Inorganic fine particles 1 to 6]
Commercially available silica fine particles having different particle sizes were surface-treated with 4% by mass of hexamethyldisilazane and used as the inorganic fine particles. The particle size of the obtained inorganic fine particles is shown in Table 1.

<Production example of toner particles 1 after heat treatment>
・ 80 parts by mass of the amorphous polyester resin L ・ 20 parts by mass of the amorphous polyester resin H ・ 5 parts by mass of the crystalline polyester resin ・ Fishertroph wax (hydrocarbon wax, peak temperature of maximum heat absorption peak 90 ° C.) 8 Parts by mass ・ C.I. I. Pigment Blue 15:37 parts by mass The above materials are mixed using a Henshell mixer (FM-75 type, manufactured by Mitsui Mine Co., Ltd.) at a rotation speed of 20 s ^-1 and a rotation time of 5 min, and then a twin-screw kneader (PCM). Kneaded with -30 type, manufactured by Ikekai Co., Ltd.). The barrel temperature at the time of kneading was set so that the outlet temperature of the kneaded product was 120 ° C. The outlet temperature of the kneaded product was directly measured using a handy type thermometer HA-200E manufactured by Anritsu Meter Co., Ltd. The obtained kneaded product was cooled and coarsely pulverized with a pin mill to a volume average particle size of 100 μm or less to obtain a coarsely crushed product. The obtained coarse crushed product was finely pulverized with a mechanical crusher (T-250, manufactured by Turbo Industries, Ltd.). Further, a rotary classifier (200 TSP, manufactured by Hosokawa Micron Co., Ltd.) was used for classification to obtain toner particles. As for the operating conditions of the rotary classifier (200TSP, manufactured by Hosokawa Micron Co., Ltd.), the classification was performed at a ^{classification rotor rotation speed of 50.0 s -1.}

To 100 parts by mass of the obtained toner particles, 5.0 parts by mass of inorganic fine particles 1 was added, and a Henschel mixer (FM-75 type, manufactured by Mitsui Mine Co., Ltd.) was used at a rotation speed of 30 s ^-1 and a rotation time of 10 min. The mixture was mixed to obtain a particle mixture 1 before heat treatment. The physical characteristics are listed in Table 2.

The obtained pre-heat treatment particle mixture 1 was heat-treated by the surface treatment apparatus shown in FIG. 1 to obtain toner particles 1 after the heat treatment. The operating conditions are feed amount = 5 kg / hr, hot air temperature C = 240 ° C., hot air flow rate = 6 m ³ / min. , Cold air temperature E = 5 ° C., Cold air flow rate = 4 m ³ / min. , Cold air absolute moisture content = 3 g / m ³ , blower air volume = 20 m ³ / min. , Injection air flow rate = 1 m ³ / min. And said. The physical characteristics of the obtained heat-treated toner particles 1 are listed in Table 3.

<Production example of toner particles 2 to 13 after heat treatment>
The post-heat treatment toner particles 2 to 13 shown in Table 3 were produced in the same manner as the post-heat treatment toner particles 1 except that the pre-heat treatment particle mixture 1 was changed to the pre-heat treatment particle mixture 2 to 13 shown in Table 2. ..

[Example 1]
The weight average particle size D4 and the number average particle size D1 which are the particle size distributions of the obtained heat-treated toner 1 were measured, and D4 / D1 and the particle size difference were evaluated.

<Evaluation 1; D4 / D1>
Evaluation was performed as an index of particle size distribution. The smaller the value, the sharper the distribution. The evaluation results are shown in Table 4.
(Evaluation criteria)
A: D4 / D1 is less than 1.40 (very good)
B: D4 / D1 is 1.40 or more and less than 1.45 (good)
C: D4 / D1 is 1.45 or more and less than 1.50 (a level that is not a problem in the present invention)
D: D4 / D1 is 1.50 or more (not acceptable in the present invention)

<Evaluation 2; particle size difference>
It is important in the present invention to suppress the increase in particle size by performing heat treatment. Therefore, the evaluation of the particle size increase was performed as (weight average particle size of toner particles after heat treatment)-(weight average particle size of toner particles). The evaluation results are shown in Table 4.
A: (Weight average particle size of toner particles after heat treatment)-(Weight average particle size of toner particles) is less than 0.30 (very excellent)
B: (Weight average particle size of toner particles after heat treatment)-(Weight average particle size of toner particles) is 0.30 or more and less than 0.40 (good)
C: (Weight average particle size of toner particles after heat treatment)-(Weight average particle size of toner particles) is 0.40 or more and less than 0.50 (a level that is not a problem in the present invention).
D: (Weight average particle size of toner particles after heat treatment)-(Weight average particle size of toner particles) is 0.50 or more (not acceptable in the present invention)

[Examples 2 to 9 and Comparative Examples 1 to 4]
The evaluation was carried out in the same manner as in Example 1 except that the toner particles 2 to 13 were used after the heat treatment. The evaluation results are shown in Table 4.

Comparative Example 1 uses inorganic fine particles having a small particle size. Inorganic fine particles also adhere to the fine particles of the toner particles, so that coalescence does not proceed. The distribution will be broad.

Comparative Example 2 uses inorganic fine particles having a large particle size. Inorganic fine particles are less likely to adhere to the central particle size of the toner particles, and not only the fine particles of the toner particles but also the overall coalescence progresses. As a result, the toner particle size becomes large after the heat treatment.

In Comparative Example 3, the toner particles are large and inorganic fine particles having a small particle size are used. Inorganic fine particles also adhere to the fine particles of the toner particles, so that coalescence does not proceed. The distribution will be broad.

In Comparative Example 4, the toner particles are small and inorganic fine particles having a large particle size are used. Inorganic fine particles are less likely to adhere to the central particle size of the toner particles, and not only the fine particles of the toner particles but also the overall coalescence progresses. As a result, the toner particle size becomes large after the heat treatment.

1. 1. Raw material quantitative supply means, 2. Compressed gas flow rate adjusting means, 3. Introductory tube, 4. Protruding member, 5. Supply pipe, 6. Processing room, 7. Hot air supply means, 8. Cold air supply means, 9. Regulatory means, 10. Recovery means, 11. Hot air supply means outlet, 12. Distributor, 13. Swivel member, 14. Powder particle supply port

Claims (2)

A method for producing a toner, which comprises a mixing step of mixing inorganic fine particles with toner particles to obtain a mixture, and a heat treatment step of heat-treating the mixture with hot air to obtain toner particles after heat treatment.
The toner particles have a weight average particle size of 3.0 μm or more and 5.0 μm or less, and the proportion of particles having a particle size of 2.0 μm or less is 0.2% by volume or more and 0.5% by volume or less.
When the average circularity of the toner particles is C1 and the average circularity of the toner particles after the heat treatment is C2, the C1 and the C2 satisfy the following formula (1).
0.010 ≤ C2-C1 equation (1)
When the weight average particle size of the toner particles is D (μm) and the number average particle size of the primary particles of the inorganic fine particles is d (μm), d / D satisfies the following formula (2). Toner manufacturing method.
0.015 ≤ d / D ≤ 0.075 Equation (2) The coverage of the inorganic fine particles with respect to the toner particles having a particle size of less than 2.0 μm is 10% or less.
The method for producing a toner according to claim 1, wherein the coverage of the inorganic fine particles with respect to the toner particles having a particle size of 2.0 μm or more is 30% or more.

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