JP7746785B2 - Toner for developing electrostatic images and method of manufacturing the same - Google Patents

Description

The present invention relates to a toner for developing electrostatic images and a method for producing the same. More specifically, the present invention relates to a toner for developing electrostatic images that has excellent low-temperature fixability and fixation separation properties, and that combines good varnish processability with the effects of preventing in-machine contamination and gloss unevenness.

2. Description of the Related Art In recent years, electrophotographic image forming apparatuses have been in demand for toners for developing electrostatic images (hereinafter also simply referred to as "toners") with improved low-temperature fixability.
For such a toner, the binder resin must have a low melting temperature and melt viscosity.
Therefore, it has been proposed to improve low-temperature fixability by using a toner containing a low-melting-point release agent and a crystalline resin, and in such toners, the difference in melting points between the release agent and the crystalline resin is becoming smaller (see, for example, Patent Documents 1 and 2).

Using a toner containing a low-melting release agent and crystalline resin is useful for improving low-temperature fixability, but as mentioned above, when the difference in melting points between the release agent and the crystalline resin becomes too small, mixed crystals of the two are formed, resulting in the problem of the toner's sharp melting properties and fixation separation properties being worse than expected.

Furthermore, when mixed crystals are formed, there is a problem that when varnishing is applied after forming a toner image, the varnish does not easily penetrate into the toner image, resulting in poor varnishing processability.

In order to improve low-temperature fixability, it is useful to use a toner containing a release agent with a low melting point, which has a large difference between the toner softening point and melting point. However, with a toner containing a release agent with a low melting point, the release agent present on the surface of the image remains in a molten state when the image is transported during toner image formation.
When the release agent in the above state comes into contact with a member such as a transport roller, the release agent cools and solidifies at the contact point, causing problems such as poor transport and contamination inside the machine.
The above problem can be solved by using a toner containing a release agent with a high melting point, which has a small difference between the toner softening point and melting point. However, this leads to a problem that the balance between the wetting and spreading of the resin and the melting of the release agent deteriorates, making it difficult to achieve a smooth toner image, resulting in uneven gloss.

Japanese Patent Application Laid-Open No. 2006-251564 Japanese Patent Application Laid-Open No. 2017-21157

The present invention was made in consideration of the above problems and circumstances, and its objective is to provide a toner for developing electrostatic images that has excellent low-temperature fixability and fixation separation properties, and that combines good varnish processability with the effects of preventing in-machine contamination and gloss unevenness, as well as a method for producing the same.

In order to solve the above-mentioned problems, the present inventors have investigated the causes of the above-mentioned problems and have found that the above-mentioned problems can be solved by controlling the endothermic peak temperature derived from the release agent, which is observed during the first temperature rise process in differential scanning calorimetry of a toner for developing electrostatic images, the endothermic peak temperature of the crystalline resin, and the softening point temperature measured by a thermal flow evaluation device, so that they satisfy a relationship within a certain range, thereby arriving at the present invention.
That is, the above-mentioned problems of the present invention are solved by the following means.

1. An electrostatic charge image developing toner comprising toner base particles containing at least a binder resin and a release agent, wherein the binder resin contains at least a crystalline resin, and when the endothermic peak temperature derived from the release agent observed during a first temperature rise process in differential scanning calorimetry of the electrostatic charge image developing toner is W ₍₁₎ p (°C), the endothermic peak temperature of the crystalline resin is C ₍₁₎ p (°C), and the softening point temperature measured by a thermal flow evaluation device is Tf _1/2 (°C),
90≦Tf _1/2 (° C.)≦115
82≦W ₍₁₎ p(℃)
A toner for developing electrostatic images, which satisfies the relationships represented by the following formulas (1a) and (2a):
14 ≦W ₍₁₎ p−C ₍₁₎ p≦ 17 (1a)
5≦Tf _1/2 -W ₍₁₎ p≦36 (2a)

2. The toner for developing electrostatic images according to item 1, wherein the softening point temperature Tf _1/2 (°C) measured by the thermal flow evaluation device and the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin observed during the first temperature rise in the differential scanning calorimetry satisfy the relationship represented by the following formula (3):
Tf _1/2 -C ₍₁₎ p≦48 (3)

3. The toner for developing electrostatic images according to item 1 or 2, wherein the softening point temperature Tf _1/2 (°C) measured by the thermal flow evaluation device and the endothermic peak temperature W ₍₁₎ p (°C) attributable to the release agent observed during the first temperature rise process in the differential scanning calorimetry satisfy the relationship represented by the following formula ( 2b ):
11≦Tf _1/2 -W ₍₁₎ p≦30 (2b)

4. The toner for developing electrostatic images according to any one of items 1 to 3 , wherein the endothermic peak temperature W ₍₁₎ p (°C) derived from the release agent is within the range of 82 to 100 (°C).

5. The toner for developing electrostatic images according to any one of items 1 to 4 , wherein the crystalline resin contains a crystalline polyester.

6. The toner for developing electrostatic images according to any one of items 1 to 5 , wherein the crystalline resin is a hybrid crystalline polyester resin formed by bonding a crystalline polyester polymer segment and a vinyl resin polymer segment.

7. The toner for developing electrostatic images according to any one of items 1 to 6 , wherein the binder resin contains at least a styrene-acrylic resin.

8. A method for producing the toner for developing electrostatic images according to any one of items 1 to 7 , wherein the toner particle production step comprises a step of adding a crystalline resin particle dispersion to an amorphous resin particle dispersion, and growing toner particles at a temperature equal to or higher than the melting point of the crystalline resin.

The above-described means of the present invention can provide a toner for developing electrostatic images that is excellent in low-temperature fixability and fixation separation property, and that is compatible with good varnish processability, the effect of preventing in-machine contamination, and the effect of preventing uneven gloss.
The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

According to the present invention, by controlling the endothermic peak temperature derived from the release agent observed during the first temperature rise process in differential scanning calorimetry of a toner for developing electrostatic images, the endothermic peak temperature of the crystalline resin, and the softening point temperature measured by a thermal flow evaluation device so that they satisfy relationships within a certain range, it is possible to achieve excellent low-temperature fixing properties and fixing separation properties, as well as good varnish processability, prevention of in-machine contamination, and prevention of uneven gloss.

If the temperature obtained by subtracting the endothermic peak temperature of the crystalline resin from the endothermic peak temperature of the release agent observed during the first temperature rise process in differential scanning calorimetry of the toner for developing electrostatic images is lower than 11°C, the release agent and the crystalline resin will form mixed crystals during the toner production, the low-temperature fixability of the toner will deteriorate due to the compatibility of the crystalline resin with the binder resin, the amount of exudation of the release agent onto the image surface will also decrease, and the fixing separation property will be poor.
Furthermore, when the components contained in the toner crystallize on the image, the release agent and the crystalline resin form mixed crystals, which inhibit the penetration of varnish, thereby deteriorating varnish processability.
Therefore, by setting the temperature obtained by subtracting the endothermic peak temperature of the crystalline resin from the endothermic peak temperature of the release agent observed during the first temperature rise process in differential scanning calorimetry measurement of the toner for developing electrostatic images to 11°C or higher, good low-temperature fixing properties, fixing separation properties, and good varnish processability were achieved.

If the temperature obtained by subtracting the endothermic peak temperature of the crystalline resin from the endothermic peak temperature of the release agent observed during the first temperature rise process in differential scanning calorimetry of the toner for developing electrostatic images is higher than 23°C, the crystal growth of each component contained in the toner that was crystallized first during toner production will proceed too quickly, causing the components to bleed out of the toner, resulting in production defects.
Therefore, good toner productivity was ensured by setting the temperature obtained by subtracting the endothermic peak temperature of the crystalline resin from the endothermic peak temperature of the release agent observed during the first temperature rise process in differential scanning calorimetry of the toner for developing electrostatic images to 23°C or less.

If the temperature obtained by subtracting the endothermic peak temperature attributable to the release agent observed in the first temperature rise process in differential scanning calorimetry from the softening point temperature measured by a thermal flow evaluation device of the toner for developing electrostatic images is lower than 5°C, the balance between the wetting and spreading of the resin and the melting of the release agent deteriorates, making it difficult to obtain a smooth image and causing uneven gloss.
Therefore, the effect of preventing uneven gloss was achieved by setting the temperature obtained by subtracting the endothermic peak temperature derived from the release agent observed during the first temperature rise process in differential scanning calorimetry from the softening point temperature measured by a thermal flow evaluation device for the toner for developing electrostatic images to 5°C or higher.

When the temperature obtained by subtracting the endothermic peak temperature derived from the release agent observed in the first temperature rise process in differential scanning calorimetry from the softening point temperature measured by a thermal flow evaluation device of the toner for developing electrostatic images is higher than 36°C, low-temperature fixability can be ensured, but the melting point of the release agent is too low, and in-machine contamination by the release agent worsens.
Therefore, the effect of preventing contamination inside the machine was realized by setting the temperature obtained by subtracting the endothermic peak temperature derived from the release agent observed during the first temperature rise process in differential scanning calorimetry from the softening point temperature measured by a thermal flow evaluation device for the electrostatic image developing toner to 36°C or less.

The toner for developing electrostatic images of the present invention is a toner for developing electrostatic images comprising toner base particles containing at least a binder resin and a release agent, wherein the binder resin contains at least a crystalline resin, and the toner satisfies the relationships represented by the following formulas (1a) and (2a), where W ₍₁₎ p (°C) is the endothermic peak temperature derived from the release agent observed during the first temperature rise process in differential scanning calorimetry of the toner for developing electrostatic images, C ₍₁₎ p (°C) is the endothermic peak temperature of the crystalline resin, and Tf _1/2 (°C) is the softening point temperature measured by a thermal flow evaluation device.
This feature is a technical feature common to or corresponding to each of the following embodiments (aspects).

In an embodiment of the present invention, it is preferable from the viewpoint of the melting balance between the toner for developing electrostatic images and the crystalline resin that the softening point temperature Tf _1/2 (°C) measured by the thermal flow evaluation device and the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin observed during the first heating process in the differential scanning calorimetry satisfy the relationship represented by the formula (3).

It is preferable that the endothermic peak temperature W ₍₁₎ p (°C) derived from the release agent and the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin, which are observed during the first temperature rise in the differential scanning calorimetry, satisfy the relationship represented by the formula (1b), from the viewpoint of preventing the formation of mixed crystals of the release agent and the crystalline resin and improving the melt balance.

From the viewpoint of the melting balance between the toner for developing electrostatic images and the release agent, it is preferable that the softening point temperature Tf _1/2 (°C) measured by the thermal flow evaluation device and the endothermic peak temperature W ₍₁₎ p (°C) derived from the release agent observed during the first temperature rise process in the differential scanning calorimetry satisfy the relationship represented by the formula (2b).

From the viewpoint of productivity of the toner for developing electrostatic images, it is preferable that the endothermic peak temperature W ₍₁₎ p (° C.) derived from the release agent is within the range of 64 to 100 (° C.).

From the viewpoint of the melting property of the toner for developing electrostatic images, it is preferable that the softening point temperature Tf _1/2 (° C.) measured by the thermal flow evaluation device is within the range of 90 to 115 (° C.).

It is preferable that the crystalline resin contains a crystalline polyester, as this promotes crystallization of the release agent in the toner for developing electrostatic images.

It is preferable that the crystalline resin be a hybrid crystalline polyester resin formed by bonding a crystalline polyester polymer segment with a vinyl resin polymer segment, from the viewpoint of suppressing bleed-out of the crystalline polyester in the electrostatic image developing toner.

It is preferable that the binder resin contain at least a styrene-acrylic resin in order to prevent excessive bleeding of the release agent.

The method for producing a toner for developing electrostatic images of the present invention is a method for producing the toner for developing electrostatic images of the present invention, and is characterized in that in the toner particle production process, it includes a step of adding a crystalline resin microparticle dispersion to an amorphous resin microparticle dispersion and growing toner particles at a temperature equal to or higher than the melting point of the crystalline resin.
This makes it possible to obtain a toner having the desired thermal properties described above.

The present invention, its components, and modes and aspects for implementing the invention are described in detail below. Note that in this application, the symbol "to" is used to mean that the numerical values before and after it are included as both the lower limit and upper limit.

[Outline of the toner for developing electrostatic images of the present invention]
The toner for developing electrostatic images of the present invention is a toner for developing electrostatic images comprising toner base particles containing at least a binder resin and a release agent, wherein the binder resin contains at least a crystalline resin, and the toner satisfies the relationships represented by the following formulas (1a) and (2a), where W ₍₁₎ p (°C) is the endothermic peak temperature derived from the release agent observed during the first temperature rise process in differential scanning calorimetry of the toner for developing electrostatic images, C ₍₁₎ p (°C) is the endothermic peak temperature of the crystalline resin, and Tf _1/2 (°C) is the softening point temperature measured by a thermal flow evaluation device.
11≦W ₍₁₎ p−C ₍₁₎ p≦23 (1a)
5≦Tf _1/2 -W ₍₁₎ p≦36 (2a)

1. Characteristics of Thermal Properties of Toner for Developing Electrostatic Images The toner according to the present invention (hereinafter also referred to simply as "toner") has a characteristic that, as properties when heat is applied, i.e., thermal properties, the endothermic temperature measured by differential scanning calorimetry and the softening point temperature measured by a thermal flow evaluation device satisfy the relationships expressed by the above-mentioned formulas (1a) and (2a).
The method and conditions for measuring the thermal properties of the toner of the present invention will be described below.

(1.1) Measurement Method by Differential Scanning Calorimetry In the present invention, the thermal properties of the toner are measured by differential scanning calorimetry (hereinafter also referred to as "DSC") as follows.
In the present invention, the measurement is particularly performed using "heat flux DSC," a measurement method in which the temperature difference between a sample and a reference material is detected while the temperature is changed according to a controlled program, and the temperature difference is converted into heat flow. Specifically, the measurement is performed according to the following procedure.

The measurement sample is placed in a measurement container called a pan.
A pan containing a measurement sample is placed on the sample sensor, and an empty pan is placed on the reference sensor and measurements are taken.

Specifically, 5 mg of the sample to be measured (each release agent and crystalline resin) was sealed in an aluminum pan KIT NO. B0143013 and placed in the sample holder of a thermal analyzer "Diamond DSC (manufactured by PerkinElmer)." The temperature was then changed in the following order: heating (first heating process), cooling, and heating (second heating process).

During the first and second heating (heating process), the temperature was raised from 0°C to 100°C at a rate of 10°C/min and held at 100°C for 1 minute, and during cooling, the temperature was lowered from 100°C to 0°C at a rate of 10°C/min and held at 0°C for 1 minute.
In the endothermic curve obtained during the first heating (temperature rise process), the endothermic peak temperature derived from the release agent is measured as W ₍₁₎ p (°C), and the endothermic peak temperature of the crystalline resin is measured as C ₍₁₎ p (°C).
An empty aluminum pan was used as a reference.

In the present invention, the "endothermic peak temperature" in differential scanning calorimetry refers to the temperature corresponding to the peak in the endothermic curve obtained in the first or second temperature rise process.
Here, the term "peak" refers to a protruding apex (extreme value) portion that indicates an endothermic phenomenon relative to the baseline.

(1.2) Thermal properties observed during the first heating process When the endothermic peak temperature derived from the release agent observed during the first heating process in differential scanning calorimetry of the toner of the present invention is defined as W ₍₁₎ p (°C), the endothermic peak temperature of the crystalline resin is defined as C ₍₁₎ p (°C), and the softening point temperature measured by a thermal flow evaluation device is defined as Tf _1/2 (°C), the toner is characterized by being adjusted so that the relationships represented by the following formulas (1a) and (2a) hold, and the reasons for this will be explained in detail.
11≦W ₍₁₎ p−C ₍₁₎ p≦23 (1a)
5≦Tf _1/2 -W ₍₁₎ p≦36 (2a)

(a) When the temperature difference obtained by subtracting the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin from the endothermic peak temperature W ( ₁ ) p (°C) of the release agent observed during the first temperature rise process in differential scanning calorimetry of the toner is lower than 11 (°C), the release agent and the crystalline resin become mixed crystals during toner production, and the low-temperature fixability deteriorates due to the compatibility of the crystalline resin with the binder resin, and the amount of release agent that seeps out onto the image surface also decreases, thereby worsening fixation separation properties.
(b) Furthermore, when an image is formed using toner, a mixed crystal of the release agent and the crystalline resin is formed when the toner crystallizes on the image, which becomes a factor that hinders the penetration of varnish during varnishing, thereby deteriorating the varnishing processability.

(c) If the temperature difference obtained by subtracting the endothermic peak temperature W ₍₁₎ p (°C) of the crystalline resin from the endothermic peak temperature W (1) p ₍ °C) of the release agent observed during the first heating process in differential scanning calorimetry of the toner is higher than 23 (°C), the crystal growth of the material that crystallized first during toner production will proceed too quickly, causing the crystallized material to bleed out of the toner, which will result in defective toner production.

(d) Furthermore, if the temperature difference obtained by subtracting the endothermic peak temperature W (1) p (°C) derived from the release agent observed during the first heating process in differential scanning calorimetry of the toner from the softening point temperature _{Tf 1/2 (} °C) measured by the thermal flow evaluation device is lower than 5 (°C), the balance between the wetting and spreading of the resin onto the image and the melting of the release agent deteriorates, making it difficult to make the image smooth and causing uneven gloss.

(e) If the temperature difference obtained by subtracting the endothermic peak temperature W (1) p (°C) attributable to the release agent observed during the first temperature rise process in differential scanning calorimetry of the toner from the softening point temperature Tf _{1/2 (} °C) measured by the thermal flow evaluation device is higher than 35 (°C), low-temperature fixability can be ensured, but the melting point of the release agent is too low, which worsens in-machine contamination by the release agent.

Therefore, when the endothermic peak temperature derived from the release agent observed during the first temperature rise process in differential scanning calorimetry of the electrostatic image developing toner is defined as W ₍₁₎ p (°C), the endothermic peak temperature of the crystalline resin is defined as C ₍₁₎ p (°C), and the softening point temperature measured by a thermal flow evaluation device is defined as Tf _1/2 (°C), the problems (a) to (e) above can be solved by satisfying the relationships represented by the formulas (1a) and (2a).

(1.2.1) Endothermic Peak Temperature of the Release Agent The "endothermic peak temperature of the release agent" according to the present invention refers to the endothermic peak temperature of the release agent in the endothermic curve observed during the first or second heating (temperature rise process) in the above-mentioned differential scanning calorimetry. The endothermic peak temperature of the release agent in the endothermic curve obtained during the first heating (temperature rise process) is designated as W ₍₁₎ p (°C).
In the present invention, in the differential scanning calorimetry, the "endothermic peak temperature derived from the release agent" is preferably in the range of 64 to 100°C, and the peak temperature W ₍₁₎ p in the endothermic curve derived from the release agent observed during the first temperature rise is preferably in the range of 64 to 100°C from the viewpoint of productivity of the toner for developing electrostatic images.

(1.2.2) Endothermic peak temperature of crystalline resin The "endothermic peak temperature of crystalline resin" in this invention refers to the endothermic peak temperature of the crystalline resin in the endothermic curve observed during the first or second heating (heating process) in the above-mentioned differential scanning calorimetry, and the endothermic peak temperature of the crystalline resin in the endothermic curve observed during the first heating (heating process) is designated as C ₍₁₎ p (°C).
In the present invention, the "endothermic peak temperature of the crystalline resin" in differential scanning calorimetry, C ₍₁₎ p, is the peak temperature in the endothermic curve of the crystalline resin observed during the first heating process, and is preferably in the range of 60 to 85°C, more preferably in the range of 72 to 82°C.

It is preferable that the endothermic peak temperature W ₍₁₎ p (°C) derived from the release agent and the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin, which are observed during the first temperature rise in the differential scanning calorimetry, satisfy the relationship represented by the following formula (1b), from the viewpoint of preventing the formation of mixed crystals of the release agent and the crystalline resin and improving the melt balance.
14≦W ₍₁₎ p−C ₍₁₎ p≦17 (1b)

By satisfying the relationship expressed by the above formula (1b), the low-temperature fixability can be improved due to the compatibility of the crystalline resin with the binder resin, and the amount of exudation of the release agent onto the image surface can be reduced.
Furthermore, when an image is formed using toner, even if the toner crystallizes on the image, a mixed crystal of the release agent and the crystalline resin is not formed, and factors that inhibit the penetration of varnish during varnishing are eliminated, improving varnish processability.
Furthermore, since the crystal growth of the material that has crystallized earlier can be appropriately suppressed during toner production, the material does not bleed out from the toner, improving the productivity of the toner.

(1.2.3) Softening Point Temperature The "softening point temperature" of the electrostatic image developing toner according to the present invention refers to the temperature at which the toner softens and begins to deform due to an increase in temperature.

The "softening point temperature measured by a thermal flow evaluation device" of the toner for developing electrostatic images according to the present invention is a temperature measured as follows.
(Method for measuring softening point temperature)
In the present invention, the softening point of the toner for developing electrostatic images was measured using a thermal flow evaluation device (also called a "thermal melt viscosity measuring device" or "flow tester") as follows.
Specifically, using a flow tester CFT-500D (manufactured by Shimadzu Corporation), a 1 ^cm3 sample was heated at a temperature increase rate of 6°C/min, while a pressure load of 20 kg/ ^cm2 was applied with a plunger (also referred to as a "piston") to push out a nozzle with a diameter of 1 mm and a length of 1 mm. In this way, a plunger descending amount (flow value)-temperature curve (also referred to as a "softening flow curve") was drawn, and when the height of the S-shaped curve is taken as h, the temperature corresponding to h/2 (the temperature at which half of the toner has flowed out) was taken as the softening point temperature Tf1 _/2 (also referred to as the "1/2 method softening point").

The softening point temperature Tf _1/2 according to the present invention is preferably 90° C. or higher, since the melting property of the toner is not too high and the fixing and separating property is good.
The softening point temperature Tf _1/2 is preferably 115° C. or less, since the melting property of the toner is not too low and the low-temperature fixability is good.

In one embodiment of the present invention, the softening point temperature Tf _1/
From the viewpoint of the melting balance between _{the toner} for developing electrostatic images and the crystalline resin, it is preferable that the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin observed during the first temperature rise in the differential scanning calorimetry measurement satisfy the relationship represented by the following formula (3):
Tf _1/2 -C ₍₁₎ p≦48 (3)

From the viewpoint of the melting balance between the toner for developing electrostatic images and the release agent, it is preferable that the softening point temperature Tf _1/2 (°C) measured by the thermal flow evaluation device and the endothermic peak temperature W ₍₁₎ p (°C) derived from the release agent observed during the first temperature rise process in the differential scanning calorimetry satisfy the relationship represented by the following formula (2b):
11≦Tf _1/2 -W ₍₁₎ p≦30 (2b)

By satisfying the above formulas (3) and (2b), the melt balance between the electrostatic image developing toner, crystalline resin, and release agent is improved, resulting in smooth images with no uneven gloss and no in-machine contamination due to the release agent.

2. Effect of Mixed Crystals of Releasing Agent and Crystalline Resin on Toner Images Mixed crystals of releasing agent and crystalline resin are formed when the difference in melting point between them becomes small.
When the mixed crystals are formed, the sharp melting property and fixation separation property of the toner become worse than expected.
Furthermore, if mixed crystals are formed, when a toner image is formed and then processed with varnish, the varnish does not easily penetrate into the toner image, and the varnish processability deteriorates.

In this specification, "sharp melting properties of a toner" refers to a state in which, for example, in a differential scanning calorimeter measurement at a constant heating rate, the difference between the melting start temperature and the melting end temperature in the DSC curve is small and the peak of the DSC curve is sharp.

(2.1) Method for Confirming the State of Mixed Crystals Whether or not the mixed crystals are formed in the toner was confirmed by observing the cross section of the toner particles under the following conditions.

(conditions)
Equipment: Scanning transmission electron microscope "JSM-7401F" (manufactured by JEOL Ltd.)
Sample: Section of toner particles stained with ruthenium tetroxide (RuO ₄ ) (section thickness: 60 to 100 nm)
Acceleration voltage: 30 kV
Magnification: 10000x (bright field image)

(2.2) Method for Producing Slices of Toner Particles The method for producing slices of toner particles under the above conditions is described below.

(Method for preparing slices of toner particles)
The toner is exposed to a ruthenium tetroxide (RuO ₄ ) vapor atmosphere for 10 minutes, then dispersed in a photocurable resin "D-800" (manufactured by JEOL Ltd.), and then photocured to form a block.
Next, a thin sample having a thickness of 60 to 100 nm is cut out from the block using a microtome equipped with diamond teeth, and placed on a grid with a support film for observation under a transmission electron microscope.
A filter paper is placed on a 5 cm diameter plastic dish, and the grid with the slices placed on it is placed with the slice-side facing up.

(2.3) Ruthenium Tetroxide Staining Conditions The ruthenium tetroxide staining conditions used in the above (method of preparing slices of toner particles) are shown below.

(Ruthenium tetroxide staining conditions)
The staining conditions (time, temperature, concentration and amount of staining agent) are adjusted so that each resin can be distinguished when observed under a transmission electron microscope.
For example, 2 to 3 drops of 0.5% RuO ₄ staining solution are dropped onto two points in a petri dish, the dish is covered, and after 10 minutes, the dish is uncovered and left to stand until the water in the staining solution has evaporated.

3. Constitution of Electrostatic Image Developing Toner The electrostatic image developing toner of the present invention is a toner for electrostatic image development comprising toner base particles containing at least a binder resin and a release agent, wherein the binder resin contains at least a crystalline resin, and the toner satisfies the relationships represented by the following formulas (1a) and (2a), where W ₍₁₎ p (°C) is the endothermic peak temperature derived from the release agent observed during a first temperature rise process in differential scanning calorimetry of the electrostatic image developing toner, C ₍₁ ) p (°C) is the endothermic peak temperature of the crystalline resin, and Tf _1/2 (°C) is the softening point temperature measured by a thermal flow evaluation device.

(3.1) Toner Base Particles The toner base particles according to the present invention may contain other components such as other colorants, charge control agents, and external additives in addition to the binder resin and the release agent.
In the present invention, the term "toner particles" refers to toner base particles to which an external additive has been added, and an aggregate of toner particles is called "toner."
Generally, the toner base particles can be used as they are as toner particles, but in the present invention, the toner base particles to which an external additive is added are used as toner particles.
In the following description, when there is no need to particularly distinguish between toner base particles and toner particles, they are also simply referred to as "toner particles."
Hereinafter, each of the constituent materials of the toner base particles according to the present invention will be described in detail.

(3.2) Binder Resin The binder resin contained in the toner base particles contained in the electrostatic image developing toner of the present invention contains at least a crystalline resin.
The term "binding resin (also referred to as "binder resin")" refers to a resin that is used as a medium or matrix (parent body) for dispersing and retaining internal additives (releasing agents, charge control agents, colorants, etc.) and external additives (silica, titanium oxide, etc.) contained in toner particles, and that has the function of adhering to a recording medium (e.g., paper) during the fixing process of a toner image.
In the toner of the present invention, conventionally known binder resins, such as crystalline resins and amorphous resins, can be used as the binder resin.
The binder resin preferably contains at least a styrene-acrylic resin.
By including the styrene-acrylic resin, excessive bleeding of the release agent during toner fixing can be suppressed, the fixing separation property can be improved, and contamination inside the machine due to the release agent can be suppressed.
Furthermore, other known resins may be contained within the range that does not impair the effects of the present invention.

(3.2.1) Crystalline Resin The crystalline resin according to the present invention refers to a resin that exhibits a clear endothermic peak, rather than a stepwise endothermic change, in the DSC of the crystalline resin or toner particles.
Specifically, a clear endothermic peak means a peak whose half-width is within 15°C when measured by DSC at a temperature rise rate of 10°C/min.

The melting point (Tm) of the crystalline resin is more preferably within the range of 62 to 82° C. in order to obtain sufficient low-temperature fixability and high-temperature storage stability.
In the present invention, the "melting point" refers to the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin observed during the first temperature rise in differential scanning calorimetry.

The crystalline resin is not particularly limited, but examples thereof include polyolefin-based resins, polydiene-based resins, and polyester-based resins.
Among these, crystalline polyester resins are preferred from the viewpoint of ease of use, as they can provide sufficient low-temperature fixability and gloss uniformity.

The number average molecular weight (Mn) of the crystalline resin is preferably in the range of 2,500 to 5,000, and more preferably in the range of 3,000 to 4,500.
From the viewpoint of low-temperature fixability and gloss stability, the number average molecular weight (Mn) of the crystalline resin is preferably in the range of 3,000 to 12,500, and more preferably in the range of 4,000 to 11,000.
The weight average molecular weight (Mw) of the crystalline resin is preferably in the range of 10,000 to 100,000, more preferably in the range of 15,000 to 80,000, and even more preferably in the range of 20,000 to 50,000.

The crystalline resin is preferably a hybrid crystalline polyester resin formed by bonding a crystalline polyester polymer segment and a vinyl resin polymer segment, from the viewpoint of suppressing bleeding out of the crystalline polyester in the toner for developing electrostatic images.
As described above, the suppression of bleed-out improves the productivity of the toner.

The content of the crystalline resin in the toner base particles is preferably within the range of 5 to 20% by mass from the viewpoint of achieving both good low-temperature fixability and good transferability in a high-temperature, high-humidity environment.
When the content is 5% by mass or more, the low-temperature fixability of the formed toner image is sufficient.
If the content is 20% by mass or less, the transferability is sufficient.

(Acid value)
From the viewpoint of productivity, the acid value of the crystalline resin is preferably within the range of 10 to 30 mgKOH/g.
When the concentration is 10 mgKOH/g or more, the amount of carboxyl group is sufficient, and it is possible to avoid the situation where emulsification becomes impossible. When the concentration is 30 mgKOH/g or less, it is possible to avoid the particle size of the latex at the completion of emulsification becoming extremely small, and as a result, it is possible to prevent the generation of residues during production.

[Method for measuring acid value]
The acid value is the mass of potassium hydroxide (KOH) required to neutralize the acid contained in 1 g of a sample, expressed in mg units. The acid value of a resin is measured according to JIS K0070-1966 by the following procedure.

[Preparation of reagents]
Dissolve 1.0 g of phenolphthalein in 90 mL of ethyl alcohol (95% by volume) and add ion-exchanged water to make 100 mL to prepare a phenolphthalein solution. Dissolve 7 g of JIS special grade potassium hydroxide in 5 mL of ion-exchanged water and add ethyl alcohol (95% by volume) to make 1 liter. Place in an alkali-resistant container to avoid contact with carbon dioxide and store for 3 minutes.
After leaving it for 3 days, filter it and prepare a potassium hydroxide solution. Standardization is in accordance with the description of JIS K0070-1966.

[Main test]
2.0 g of the crushed sample is accurately weighed into a 200 mL Erlenmeyer flask, and 100 mL of a toluene/ethanol (2:1) mixed solution is added and dissolved over 5 hours. Next, a few drops of the prepared phenolphthalein solution are added as an indicator, and the sample is titrated with the prepared potassium hydroxide solution. The endpoint of the titration is when the light red color of the indicator persists for approximately 30 seconds.

[Blank test]
The same procedure as in the main test above is carried out except that no sample is used (i.e., only the toluene/ethanol (2:1) mixed solution is used).

The titration results of the main test and the blank test are substituted into the following formula (1) to calculate the acid value.
Formula (1) A=[(B-C)×f×5.6]/S
A: Acid value (mgKOH/g)
B: Amount of potassium hydroxide solution added during blank test (mL)
C: Amount of potassium hydroxide solution added during this test (mL)
f: Factor of 0.1 mol/L potassium hydroxide ethanol solution S: Mass of sample (g)

(3.2.2) Crystalline Polyester Resin The binder resin is preferably a crystalline polyester resin from the viewpoint of promoting crystallization of the release agent in the toner for developing electrostatic images.
As described above, the crystallization is promoted, and thus adhesion of the release agent can be suppressed.
The crystalline polyester resin refers to a polyester resin among the above-mentioned crystalline resins.
The crystalline polyester resin is obtained by a polycondensation reaction between a divalent or higher carboxylic acid (a polycarboxylic acid) and a divalent or higher alcohol (a polyhydric alcohol).

(Polycarboxylic Acid)
Examples of polycarboxylic acids include dicarboxylic acids.
The dicarboxylic acid may be one or more kinds, and is preferably an aliphatic dicarboxylic acid, and may further contain an aromatic dicarboxylic acid.
The aliphatic dicarboxylic acid is preferably a straight chain type from the viewpoint of enhancing the crystallinity of the crystalline polyester resin.

[Aliphatic dicarboxylic acids]
Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (dodecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, lower alkyl esters thereof, and acid anhydrides thereof.
Among these, aliphatic dicarboxylic acids having 6 to 16 carbon atoms are preferred, and aliphatic dicarboxylic acids having 10 to 14 carbon atoms are more preferred, from the viewpoint of easily achieving both low-temperature fixability and transferability.

[Aromatic dicarboxylic acid]
Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid.
Among these, terephthalic acid, isophthalic acid, and t-butylisophthalic acid are preferred from the viewpoints of availability and ease of emulsification.

[Dicarboxylic acid content]
From the viewpoint of ensuring sufficient crystallinity of the crystalline polyester resin, the content of the aliphatic dicarboxylic acid-derived structural units relative to the dicarboxylic acid-derived structural units in the crystalline polyester resin is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%.

(Polyhydric alcohol)
Examples of the polyhydric alcohol component include diols.
The diol may be one or more kinds, and is preferably an aliphatic diol, and may further contain other diols.
The aliphatic diol is preferably a straight-chain type from the viewpoint of increasing the crystallinity of the crystalline polyester resin.

[Aliphatic diol]
Examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol.
Among these, aliphatic diols having 2 to 120 carbon atoms are preferred, and aliphatic diols having 4 to 6 carbon atoms are more preferred, from the viewpoint of easily achieving both low-temperature fixability and transferability.

[Other diols]
Other examples of the diol include a diol having a double bond and a diol having a sulfonic acid group.
Specific examples of diols having a double bond include 2-butene-1,4-diol, 3-hexene-1,6-diol, and 4-octene-1,8-diol.

[Aliphatic diol content]
The content of the aliphatic diol-derived structural units relative to the diol-derived structural units in the crystalline polyester resin is preferably 50 mol % or more, more preferably 70 mol % or more, even more preferably 80 mol % or more, and particularly preferably 100 mol %, from the viewpoint of improving the low-temperature fixability of the toner and the glossiness of the image finally formed.

(Ratio of diol to dicarboxylic acid)
The ratio of the diol to the dicarboxylic acid in the monomer of the crystalline polyester resin is preferably in the range of 2.0/1.0 to 1.0/2.0, more preferably in the range of 1.5/1.0 to 1.0/1.5, and particularly preferably in the range of 1.3/1.0 to 1.0/1.3, in terms of the equivalent ratio [OH]/[COOH] of the hydroxy group [OH] of the diol to the carboxy group [COOH] of the dicarboxylic acid.

(Melting point of crystalline polyester resin)
The melting point (Tm) of the crystalline polyester resin is more preferably within the range of 62 to 82° C. in order to obtain sufficient low-temperature fixability and high-temperature storage stability.

The melting point of the crystalline polyester resin can be measured using the DSC measurement method described above.

(Weight-average molecular weight and number-average molecular weight of crystalline polyester resin)
Furthermore, it is preferable that the weight average molecular weight (Mw) of the crystalline polyester resin is in the range of 5,000 to 50,000 and the number average molecular weight (Mn) is in the range of 2,000 to 10,000 from the viewpoints of low-temperature fixability and stable gloss development in the final image.

The weight average molecular weight (Mw) and number average molecular weight (Mn) can be determined from the molecular weight distribution measured by gel permeation chromatography (GPC) as follows:

The sample is added to tetrahydrofuran (THF) to a concentration of 1 mg/mL, dispersed at room temperature using an ultrasonic disperser for 5 minutes, and then passed through a membrane filter with a pore size of 0.2 μm to prepare the sample solution.

Using a GPC system HLC-8120GPC (manufactured by Tosoh Corporation) and a column "TSKguard column + TSKgel Super HZM-M triple column" (manufactured by Tosoh Corporation), THF was used as a carrier solvent at a flow rate of 0.2 mL/min while maintaining the column temperature at 40°C. 10 μL of the prepared sample solution was injected into the GPC system together with the carrier solvent, and the sample was detected using a refractive index detector (RI detector).
Then, the molecular weight distribution of the sample is calculated using a calibration curve measured using 10 points of monodisperse polystyrene standard particles.

(Synthesis of crystalline polyester resin)
The crystalline polyester resin can be synthesized by polycondensing (esterifying) the polycarboxylic acid and the polyhydric alcohol using a known esterification catalyst.

〔catalyst〕
The catalyst that can be used in the synthesis of the crystalline polyester resin may be one or more types, and examples thereof include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphorous compounds; phosphoric acid compounds; and amine compounds.

Specific examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and salts thereof.
Examples of titanium compounds include titanium alkoxides such as tetra-normal-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolamine.
Examples of germanium compounds include germanium dioxide, and examples of aluminum compounds include oxides such as aluminum polyhydroxide, aluminum alkoxides, and tributylaluminate.
Of the above compounds, tin compounds are preferred.

[Polymerization temperature]
The polymerization temperature for the crystalline polyester resin is preferably within a range of 150 to 250° C. The polymerization time is preferably within a range of 0.5 to 10 hours. During the polymerization, the pressure in the reaction system may be reduced as necessary.

(3.2.3) Amorphous Resin One or more types of amorphous resin may be used, and examples of the amorphous resin include vinyl resins, urethane resins, urea resins, and amorphous polyester resins such as styrene-acrylic modified polyester resins.
Among these, from the viewpoint of easy control of thermoplasticity, it is preferable that the binder resin contains a vinyl resin as the main component, and it is preferable that the vinyl resin accounts for 50% or more of the entire binder resin.

(Weight average molecular weight of amorphous resin)
The weight average molecular weight (Mw) of the amorphous resin is preferably in the range of 5,000 to 150,000, more preferably in the range of 10,000 to 70,000, from the viewpoint of ease of controlling its plasticity.

(3.2.4) Vinyl Resin The vinyl resin is, for example, a polymer of a vinyl compound, and examples thereof include acrylic ester resin, styrene-acrylic ester resin, and ethylene-vinyl acetate resin.
Among these, styrene-acrylic ester resin (styrene-acrylic resin) is preferred from the viewpoint of plasticity during thermal fixing.

(styrene-acrylic resin)
The amorphous resin contained as the binder resin preferably contains at least a styrene-acrylic resin from the viewpoint of suppressing excessive bleeding of the release agent.
By suppressing excessive bleeding of the release agent as described above, the fixing and separating properties of the toner are improved, and the effect of preventing contamination inside the machine is exhibited.

The styrene-acrylic resin is formed by addition polymerization of at least a styrene monomer and a (meth)acrylic acid ester monomer.
Styrene monomers include styrene represented by the structural formula CH ₂ ═CH—C ₆ H ₅ , as well as styrene derivatives having known side chains or functional groups in the styrene structure.

[(Meth)acrylic acid ester monomer]
The (meth)acrylic acid ester monomer includes not only acrylic acid esters and methacrylic acid esters represented by CH(R _a )═CHCOOR _b (R _a represents a hydrogen atom or a methyl group, and R _b represents an alkyl group having 1 to 24 carbon atoms), but also acrylic acid ester derivatives and methacrylic acid ester derivatives having known side chains or functional groups in the structure of these esters.

Examples of the (meth)acrylic acid ester monomer include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate.

In this specification, "(meth)acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer," and means either or both of them.

For example, "methyl (meth)acrylate" means one or both of "methyl acrylate" and "methyl methacrylate."

The (meth)acrylic acid ester monomer may be one or more kinds.
For example, it is possible to form a copolymer using a styrene monomer and two or more acrylic acid ester monomers, to form a copolymer using a styrene monomer and two or more methacrylic acid ester monomers, or to form a copolymer using a styrene monomer in combination with an acrylic acid ester monomer and a methacrylic acid ester monomer.

[Styrene monomer]
Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, and p-n-dodecylstyrene.

[Content]
From the viewpoint of controlling the plasticity of the styrene-acrylic resin, the content of structural units derived from styrene monomers in the styrene-acrylic resin is preferably within the range of 40 to 90% by mass.
The content of the structural units derived from the (meth)acrylic acid ester monomer in the styrene-acrylic resin is preferably within a range of 10 to 60% by mass.

[Other monomers]
The styrene-acrylic resin may further contain structural units derived from other monomers than the styrene monomer and the (meth)acrylic acid ester monomer.
The other monomer is preferably a compound that forms an ester bond with a hydroxy group (—OH) derived from a polyhydric alcohol or a carboxy group (—COOH) derived from a polycarboxylic acid.
That is, the styrene-acrylic resin is preferably a polymer that can be addition-polymerized with the styrene monomer and the (meth)acrylic acid ester monomer, and is further polymerized with a compound having a carboxyl group or a hydroxyl group (an amphoteric compound).

[Amphoteric compounds]
Examples of the amphoteric compound include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl esters, and itaconic acid monoalkyl esters, and compounds having a hydroxy group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[Content of structural units derived from amphoteric compounds]
The content of the structural unit derived from the amphoteric compound in the styrene-acrylic resin is preferably within a range of 0.5 to 20% by mass.

[Synthesis method]
The styrene-acrylic resin can be synthesized by polymerizing monomers using a known oil-soluble or water-soluble polymerization initiator.
Examples of oil-soluble polymerization initiators include azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators.

[Azo or diazo polymerization initiator]
Examples of the azo or diazo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

[Peroxide-based polymerization initiator]
Examples of the peroxide polymerization initiator include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, and tris-(t-butylperoxy)triazine.

[Water-soluble radical polymerization initiator]
When resin particles of styrene-acrylic resin are synthesized by emulsion polymerization, a water-soluble radical polymerization initiator can be used as the polymerization initiator.
Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

(3.2.5) Hybrid Crystalline Polyester Resin The above-mentioned crystalline polyester resin may contain a hybrid crystalline polyester resin (hereinafter also simply referred to as "hybrid resin").

By including the hybrid crystalline resin, the affinity with the amorphous resin used in combination is improved, and therefore the low temperature fixability of the toner is improved.
Furthermore, the dispersibility of the crystalline resin in the toner is improved, so that bleeding out can be suppressed.

The hybrid resin may be one or more types.
The hybrid resin may replace the entire amount of the crystalline polyester resin, or may replace a part of the crystalline polyester resin, or may be used in combination with the hybrid resin.

The hybrid resin is a resin in which a crystalline polyester polymer segment and an amorphous polymer segment are chemically bonded.
The crystalline polyester polymer segment refers to a portion derived from the crystalline polyester resin.
That is, the term "amorphous polymer segment" refers to a molecular chain having the same chemical structure as the molecular chain constituting the crystalline polyester resin described above. The term "amorphous polymer segment" refers to a portion derived from the amorphous resin.
That is, it means a molecular chain having the same chemical structure as the molecular chain constituting the above-mentioned amorphous resin.

(Weight average molecular weight)
The weight average molecular weight (Mw) of the hybrid resin is preferably in the range of 5,000 to 100,000, more preferably in the range of 7,000 to 50,000, and particularly preferably in the range of 8,000 to 20,000, from the viewpoint of reliably achieving both sufficient low-temperature fixability and excellent long-term storage stability.
By adjusting the weight average molecular weight (Mw) of the hybrid resin to 100,000 or less, sufficient low-temperature fixability can be obtained.
On the other hand, by setting the weight average molecular weight (Mw) of the hybrid resin to 5,000 or more, excessive compatibility between the hybrid resin and the amorphous resin during toner storage is suppressed, and image defects due to fusion of toner particles can be effectively suppressed.

(Crystalline polyester polymer segment)
The crystalline polyester polymer segment may be, for example, a resin having a structure in which other components are copolymerized into a main chain of a crystalline polyester polymer segment, or a resin having a structure in which a crystalline polyester polymer segment is copolymerized into a main chain made of other components.
The crystalline polyester polymer segment can be synthesized from the above-mentioned polycarboxylic acid and polyhydric alcohol in the same manner as the above-mentioned crystalline polyester resin.

From the viewpoint of imparting sufficient crystallinity to the hybrid resin, the content of the crystalline polyester polymer segment in the hybrid resin is preferably within a range of 80 to 98 mass%, more preferably within a range of 90 to 95 mass%, and even more preferably within a range of 91 to 93 mass%.
The constituent components and contents of each polymer segment in the hybrid resin (or in the toner) can be identified by using known analytical methods such as nuclear magnetic resonance (NMR) and methylation reaction pyrolysis gas chromatography/mass spectrometry (Py-GC/MS).

It is preferable that the crystalline polyester polymer segment further contains a monomer having an unsaturated bond, from the viewpoint of introducing chemical bonding sites with the amorphous polymer segment into the segment.

Monomers having unsaturated bonds include, for example, polyhydric alcohols having double bonds, and examples thereof include polycarboxylic acids having double bonds such as methylene succinic acid, fumaric acid, maleic acid, 3-hexenedioic acid, and 3-octenedioic acid; 2-butene-1,4-diol, 3-hexene-1,6-diol, and 4-octene-1,8-diol.

The content of the structural units derived from the monomer having an unsaturated bond in the crystalline polyester polymer segment is preferably within the range of 0.5 to 20% by mass.

The hybrid resin may be a block copolymer or a graft copolymer, but a graft copolymer is preferred from the viewpoint of making it easier to control the orientation of the crystalline polyester polymerized segments and imparting sufficient crystallinity to the hybrid resin, and it is more preferred that the crystalline polyester polymerized segments are grafted onto the amorphous polymerized segments as the main chain.
That is, the hybrid resin is preferably a graft copolymer having the amorphous polymer segment as the main chain and the crystalline polyester polymer segment as the side chain.

The hybrid resin may further contain functional groups such as sulfonic acid groups, carboxy groups, and urethane groups.
The functional group may be introduced into the crystalline polyester polymer segment or into the amorphous polymer segment.

(Amorphous polymerized segment)
The amorphous polymer segment enhances the affinity between the amorphous resin constituting the binder resin and the hybrid resin.
This makes it easier for the hybrid resin to be incorporated into the amorphous resin, further improving the charging uniformity of the toner.
The constituent components of the amorphous polymer segment in the hybrid resin (or in the toner) and their content can be identified by using known analytical methods such as NMR or methylation reaction Py-GC/MS.

Similarly to the amorphous resin according to the present invention, the amorphous polymer segment preferably has a glass transition temperature (Tg ₁ ) observed during the first heating step of DSC in the range of 30 to 80°C, more preferably 40 to 65°C.
The glass transition temperature (Tg ₁ ) can be measured by a known method (for example, DSC).

The amorphous polymer segment is preferably composed of the same type of resin as the amorphous resin contained in the binder resin, from the viewpoint of increasing affinity with the binder resin and improving the charging uniformity of the toner.
By adopting such a form, the affinity between the hybrid resin and the amorphous resin is further improved.
The term "same type of resin" means resins having characteristic chemical bonds in the repeating units.

"Characteristic chemical bonds" refer to the "Polymer Classification" listed in the National Institute for Materials Science (NIMS) Materials Database (http://polymer.nims.go.jp/PolyInfo/guide/jp/term_polymer.html). Specifically, "characteristic chemical bonds" refer to the chemical bonds that make up polymers classified into a total of 22 types: polyacrylic, polyamide, polyanhydride, polycarbonate, polydienes, polyesters, polyhaloolefins, polyimides, polyimines, polyketones, polyolefins, polyethers, polyphenylenes, polyphosphazenes, polysiloxanes, polystyrenes, polysulfides, polysulfones, polyurethanes, polyureas, polyvinyls, and other polymers.

Furthermore, when the resin is a copolymer, "same type of resin" means resins that have a characteristic chemical bond in common when the chemical structures of multiple monomer species that make up the copolymer each have a monomer species having the above-mentioned chemical bond as a constituent unit.
Therefore, even if the properties of the resins themselves are different from each other or the molar component ratios of the monomer species that make up the copolymer are different from each other, they are considered to be the same type of resin as long as they have characteristic chemical bonds in common.

For example, a resin (or polymerized segment) formed from styrene, butyl acrylate, and acrylic acid and a resin (or polymerized segment) formed from styrene, butyl acrylate, and methacrylic acid are the same type of resin because they contain at least the chemical bonds that make up polyacrylic.

For example, a resin (or a polymerized segment) formed from styrene, butyl acrylate, and acrylic acid and a resin (or a polymerized segment) formed from styrene, butyl acrylate, acrylic acid, terephthalic acid, and fumaric acid have at least a chemical bond constituting polyacrylic as a common chemical bond.
Therefore, they are the same type of resin.

Examples of the amorphous polymerized segment include a vinyl polymerized segment, a urethane polymerized segment, and a urea polymerized segment.
Among these, a vinyl polymer segment is preferred from the viewpoint of ease of controlling thermoplasticity.
The vinyl polymer segment can be synthesized in the same manner as the vinyl resin according to the present invention.

The content of structural units derived from styrene monomers in the amorphous polymer segment is preferably within the range of 40 to 90% by mass, from the viewpoint of facilitating control of the plasticity of the hybrid resin.
From the same viewpoint, the content of structural units derived from (meth)acrylic acid ester monomers in the amorphous polymer segment is preferably within the range of 10 to 60% by mass.

Furthermore, it is preferable that the amorphous polymer segment further contains the above-mentioned amphoteric compound as a monomer, from the viewpoint of introducing a chemical bonding site with the crystalline polyester polymer segment into the amorphous polymer segment.
The content of the constitutional unit derived from the amphoteric compound in the amorphous polymer segment is preferably within a range of 0.5 to 20% by mass.

From the viewpoint of imparting sufficient crystallinity to the hybrid resin, the content of the amorphous polymer segment in the hybrid resin is preferably within the range of 3 to 15% by mass, more preferably within the range of 5 to 10% by mass, and even more preferably within the range of 7 to 9% by mass.

(Method for producing hybrid resin)
The hybrid resin can be produced, for example, by the following first to third production methods.

[First manufacturing method]
The first production method is a method for producing a hybrid resin by carrying out a polymerization reaction to synthesize a crystalline polyester polymer segment in the presence of a previously synthesized amorphous polymer segment.

In this method, the monomers that make up the amorphous polymerized segment (preferably vinyl monomers such as styrene monomers or (meth)acrylic acid ester monomers) are first subjected to an addition reaction to synthesize the amorphous polymerized segment.

Next, a polycarboxylic acid and a polyhydric alcohol are polymerized in the presence of the amorphous polymer segment to synthesize a crystalline polyester polymer segment.

In this process, a hybrid resin is synthesized by condensing a polycarboxylic acid with a polyhydric alcohol and adding the polycarboxylic acid or polyhydric alcohol to the amorphous polymer segment.

In the first method, it is preferable to incorporate a site into the crystalline polyester polymer segment or the amorphous polymer segment that allows these polymer segments to react with each other.

Specifically, when synthesizing the amorphous polymerized segment, the above-mentioned amphoteric compound is also used in addition to the monomers that constitute the amorphous polymerized segment.
The amphoteric compound reacts with the carboxyl or hydroxyl group in the crystalline polyester polymer segment, whereby the crystalline polyester polymer segment is chemically and quantitatively bonded to the amorphous polymer segment.
Furthermore, when synthesizing the crystalline polyester polymer segment, the monomer may further contain the above-mentioned compound having an unsaturated bond.

The first method described above makes it possible to synthesize a hybrid resin with a structure (graft structure) in which crystalline polyester polymer segments are molecularly bonded to amorphous polymer segments.

[Second manufacturing method]
The second production method is a method in which a crystalline polyester polymer segment and an amorphous polymer segment are formed in advance, and then these are bonded to produce a hybrid resin.

In this method, first, a crystalline polyester polymer segment is synthesized by condensation reaction of a polycarboxylic acid with a polyhydric alcohol.
Separately from the reaction system for synthesizing the crystalline polyester polymer segment, the above-mentioned monomers constituting the amorphous polymer segment are addition polymerized to synthesize the amorphous polymer segment.

In this case, it is preferable to incorporate a site into one or both of the crystalline polyester polymerized segment and the amorphous polymerized segment, which allows the crystalline polyester polymerized segment and the amorphous polymerized segment to react with each other, as described above.

Next, by reacting the synthesized crystalline polyester polymerized segment with an amorphous polymerized segment, a hybrid resin can be synthesized in which the crystalline polyester polymerized segment and the amorphous polymerized segment are molecularly bonded.

Furthermore, when the reactive site is not incorporated into either the crystalline polyester polymerization segment or the amorphous polymerization segment, a method may be adopted in which a compound having a site capable of bonding to both the crystalline polyester polymerization segment and the amorphous polymerization segment is added to a system in which the crystalline polyester polymerization segment and the amorphous polymerization segment coexist.
This makes it possible to synthesize a hybrid resin having a structure in which a crystalline polyester polymer segment and an amorphous polymer segment are molecularly bonded via the compound.

[Third manufacturing method]
The third production method is a method for producing a hybrid resin by carrying out a polymerization reaction to synthesize an amorphous polymer segment in the presence of a crystalline polyester polymer segment.

In this method, a polycarboxylic acid and a polyhydric alcohol are first polymerized through a condensation reaction to synthesize a crystalline polyester polymer segment.

Next, the monomers that make up the amorphous polymer segment are polymerized in the presence of the crystalline polyester polymer segment to synthesize the amorphous polymer segment.

In this case, similarly to the first production method, it is preferable to incorporate into the crystalline polyester polymer segment or the amorphous polymer segment a site that allows these polymer segments to react with each other.

The above-mentioned method makes it possible to synthesize a hybrid resin with a structure (graft structure) in which amorphous polymerized segments are molecularly bonded to crystalline polyester polymerized segments.

Among the first to third manufacturing methods, the first manufacturing method is preferred because it is easy to synthesize a hybrid resin having a structure in which a crystalline polyester resin chain is grafted onto an amorphous resin chain and because it simplifies the production process.
In the first production method, the amorphous polymerized segments are formed in advance and then the crystalline polyester polymerized segments are bonded to them, so that the orientation of the crystalline polyester polymerized segments tends to be uniform.

(3.3) Release agent (wax)
The release agent constituting the toner is not particularly limited, and known release agents can be used.
Specific examples include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, ester waxes such as behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellitate tristearyl, and distearyl maleate, and amide waxes such as ethylenediamine behenylamide and trimellitate tristearylamide.

The melting point of the release agent is preferably in the range of 60 to 100°C, more preferably in the range of 70 to 95°C.
By setting the melting point within the above range, the heat-resistant storage property of the toner is ensured, and even when fixing is performed at a low temperature, a stable toner image can be formed without causing cold offset or the like.
In the present invention, the "melting point" refers to the endothermic peak temperature W ₍₁₎ p (°C) derived from the release agent observed during the first temperature rise in differential scanning calorimetry.
The content of the release agent in the toner is preferably in the range of 1 to 30% by weight, and more preferably in the range of 5 to 20% by weight.

(3.4) Other Components In addition to the above-mentioned essential components, the toner of the present invention may contain, if necessary, internal additives such as colorants, charge control agents, and crystal nucleating agents, and external additives such as inorganic fine particles, organic fine particles, and lubricants.

(Coloring agent)
As colorants that can be used to form the toner, carbon black, magnetic materials, dyes, pigments, etc. can be used arbitrarily. As carbon black, channel black, furnace black, acetylene black, thermal black, lamp black, etc. can be used.
As the magnetic material, ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, ferromagnetic metal compounds such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but exhibit ferromagnetism when heat treated, for example, alloys of the type known as Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide can be used.

Black colorants include carbon blacks such as furnace black, channel black, acetylene black, thermal black, and lamp black, as well as magnetic powders such as magnetite and ferrite.

Examples of magenta or red colorants include C.I. Pigment Red 2, 3, 5, 6, 7, 15, 16, 48:1, 53:1, 57:1, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238, and 269.

Furthermore, examples of colorants for orange or yellow include C.I. Pigment Orange 31 and 43, C.I. Pigment Yellow 12, 14, 15, 17, 74, 83, 93, 94, 138, 155, 162, 180, and 185.

Furthermore, examples of colorants for green or cyan include C.I. Pigment Blue 2, 3, 15, 15:2, 15:3, 15:4, 16, 17, 60, 62, 66, and C.I. Pigment Green 7.

These colorants can be used alone or in combination with two or more selected as needed.

The amount of colorant added is preferably in the range of 1 to 30% by weight, more preferably 2 to 20% by weight, of the total toner. Mixtures of these can also be used. Within these ranges, color reproducibility of the image can be ensured.

Furthermore, the size of the colorant, in terms of volume average particle size, is preferably in the range of 10 to 1000 nm, more preferably in the range of 50 to 500 nm, and even more preferably in the range of 80 to 300 nm.

(Charge control agent)
As the charge control agent, various known compounds can be used, such as nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, and metal salicylate salts.

The amount of charge control agent added is typically within the range of 0.1 to 10% by weight, and preferably within the range of 0.5 to 5% by weight, relative to 100% by weight of the binder resin in the final toner particles.

The size of the charge control agent particles is preferably in the range of 10 to 1000 nm, more preferably 50 to 500 nm, and even more preferably 80 to 300 nm, in terms of number average primary particle diameter.

(Crystal nucleating agent)
A "nucleating agent" is an additive that promotes the crystallization of crystalline polymers. Adding a small amount to a polymer is expected to improve productivity (moldability) and mechanical properties and transparency.
The nucleating agent may be any compound capable of forming a nucleating site, and is preferably an aliphatic monocarboxylic acid having 18 to 30 carbon atoms or an aliphatic monoalcohol having 18 to 30 carbon atoms.
Specific examples include triacontanoic acid, arachidic acid, and arachidyl alcohol.
It is preferable that the crystal nucleating agent is an aliphatic monocarboxylic acid or an aliphatic monoalcohol, since it bonds to the polyester polymer segment in such a way as to cap the end of the polyester polymer segment, thereby forming a crystal nucleating agent moiety at at least one end of the polyester polymer segment.

(External additives)
From the viewpoint of improving the charging performance, fluidity, or cleaning properties of the toner, known inorganic or organic particles or lubricants may be added as external additives to the surface of the toner particles.

Preferred inorganic fine particles include inorganic fine particles made of silica, titania, alumina, strontium titanate, etc.

If necessary, these inorganic fine particles may be hydrophobized.

The organic fine particles used can be spherical organic fine particles with a number-average primary particle diameter in the range of approximately 10 to 2000 nm. Specifically, organic fine particles made from homopolymers such as styrene or methyl methacrylate, or copolymers of these, can be used.

Lubricants are used to further improve cleaning and transferability, and examples of lubricants include metal salts of higher fatty acids such as zinc, aluminum, copper, magnesium, calcium, etc. stearic acid salts; zinc, manganese, iron, copper, magnesium, etc. oleic acid salts; zinc, copper, magnesium, etc. palmitic acid salts; zinc, calcium, etc. linoleic acid salts; zinc, calcium, etc. ricinoleic acid salts; and other salts. Various external additives may be used in combination.

The amount of external additive added is preferably within the range of 0.1 to 10.0% by mass relative to 100% by mass of toner particles.

External additives can be added using various known mixing devices such as a Turbula mixer, Henschel mixer, Nauta mixer, or V-type mixer.

(3.5) Structure and Shape of Toner Particles (3.5.1) Core-shell Structure The toner base particles can be used as they are for toner, but they may also be toner particles with a multilayer structure such as a core-shell structure comprising the toner base particle as a core particle and a shell layer covering the surface of the core particle.
The shell layer does not need to cover the entire surface of the core particle, and the core particle may be partially exposed. The cross section of the core-shell structure can be confirmed by known observation means, for example, a transmission electron microscope (TEM) or a scanning probe microscope (SPM).

In the case of a core-shell structure, the core particle and shell layer can have different properties such as glass transition point, melting point, and hardness, making it possible to design toner particles according to the purpose. For example, a shell layer can be formed by aggregating and fusing a resin with a relatively high glass transition point (Tg) to the surface of a core particle containing a binder resin, colorant, release agent, etc. and having a relatively low glass transition point (Tg). The shell layer preferably contains an amorphous resin.

(3.5.2) Particle Size of Toner Particles The particle size of the toner particles is preferably such that the volume-based median diameter (d ₅₀ ) is in the range of 3 to 10 μm, and more preferably in the range of 5 to 8 μm.
Within the above range, high reproducibility can be obtained even for extremely minute dot images at the 1200 dpi level.
The particle size of the toner particles can be controlled by the concentration of the aggregating agent used during production, the amount of organic solvent added, the fusion time, the composition of the binder resin, and the like.

The volume-based median diameter (d ₅₀ ) of toner particles can be measured using a measuring device in which a computer system equipped with data processing software Software V3.51 is connected to a Multisizer 3 (manufactured by Beckman Coulter, Inc.).
Specifically, the measurement sample (toner) is added to a surfactant solution (a surfactant solution prepared by diluting, for example, a neutral detergent containing a surfactant component 10 times with pure water in order to disperse toner particles) and mixed well, and then ultrasonic dispersion is performed to prepare a toner particle dispersion.
This toner particle dispersion is poured into a beaker containing ISOTON II (manufactured by Beckman Coulter) in a sample stand using a pipette until the concentration indicated on the measuring device reaches 8%.
By using this concentration, reproducible measurement values can be obtained.
Then, in the measuring device, the number of measured particles is set to 25,000, the aperture diameter is set to 100 μm, the measurement range of 2 to 60 μm is divided into 256 parts, and the frequency value is calculated. The particle diameter of the largest 50% of the volume cumulative fraction is obtained as the volume-based median diameter (d ₅₀ ).

(3.5.3) Average Circularity of Toner Particles From the viewpoint of improving the stability of chargeability and low-temperature fixability, the average circularity of the toner particles is preferably in the range of 0.930 to 1.000, and more preferably in the range of 0.950 to 0.995.
If the average circularity is within the above range, the individual toner particles are less likely to be crushed.
This makes it possible to suppress contamination of the frictional charging member, stabilize the charging property of the toner, and improve the quality of the formed image.

The average circularity of the toner particles can be measured using FPIA-2100 (manufactured by Sysmex).
Specifically, the measurement sample (toner) is mixed with an aqueous solution containing a surfactant, and then subjected to ultrasonic dispersion treatment for 1 minute to disperse the toner.
Thereafter, an FPIA-2100 (manufactured by Sysmex) is used to take images under measurement conditions in HPF (high magnification imaging) mode at an appropriate density of 3,000 to 10,000 HPF detection numbers.
If the number of HPF detections is within the above range, reproducible measurement values can be obtained.
From the photographed particle image, the circularity of each toner particle is calculated according to the following formula (I), and the circularity of each toner particle is added up and divided by the total number of toner particles to obtain an average circularity.
Formula (I):
Circularity = (perimeter of a circle having the same projected area as the particle image) / (perimeter of the projected particle image)

4. Method for Producing Toner for Developing Electrostatic Images The method for producing the toner for developing electrostatic images of the present invention is characterized in that the method for producing the toner for developing electrostatic images of the present invention comprises a step of adding a crystalline resin particle dispersion to an amorphous resin particle dispersion and growing toner particles at a temperature equal to or higher than the melting point of the crystalline resin in the toner particle production step.
This makes it possible to obtain a toner having the desired thermal properties described above.
As the above production method, for example, an emulsion polymerization aggregation method or an emulsion aggregation method can be suitably adopted.

The emulsion polymerization aggregation method preferably used in the toner manufacturing method of the present invention is a method of manufacturing toner particles by mixing a dispersion of binder resin fine particles (hereinafter also referred to as "binder resin fine particles") manufactured by emulsion polymerization with a dispersion of colorant fine particles (hereinafter also referred to as "colorant fine particles") and a dispersion of a release agent such as wax, aggregating the toner particles until they reach the desired particle size, and then controlling the shape by fusing the binder resin fine particles together.

Furthermore, the emulsion aggregation method preferably used as the toner manufacturing method according to the present invention is a method for manufacturing toner particles by adding dropwise a binder resin solution dissolved in a solvent to a poor solvent to prepare a resin particle dispersion, mixing this resin particle dispersion with a colorant dispersion and a release agent dispersion such as wax, causing aggregation until the toner particles have a desired diameter, and further controlling the shape by fusing the binder resin particles together.
In the toner of the present invention, either of the manufacturing methods can be applied.

An example of the method for producing the toner of the present invention using the emulsion polymerization aggregation method will be described below.
(1) A step of preparing a dispersion liquid in which fine particles of a colorant are dispersed in an aqueous medium. (2) A step of preparing a dispersion liquid in which fine particles of a binder resin, optionally containing an internal additive, are dispersed in an aqueous medium. (3) A step of preparing a dispersion liquid of fine particles of a binder resin by emulsion polymerization. (4) A step of mixing a dispersion liquid of fine particles of a colorant with a dispersion liquid of fine particles of a binder resin to aggregate, associate, and fuse the fine particles of the colorant and the fine particles of the binder resin to form toner base particles. (5) A step of filtering the toner base particles from the dispersion system (aqueous medium) of the toner base particles to remove surfactants and the like. (6) A step of drying the toner base particles. (7) A step of adding external additives to the toner base particles.

When the toner is produced by the emulsion polymerization aggregation method, the binder resin particles obtained by the emulsion polymerization method may have a multilayer structure of two or more layers made of binder resins having different compositions.
Binder resin microparticles having such a configuration, for example, those having a two-layer structure, can be obtained by a method in which a dispersion of resin particles is prepared by emulsion polymerization treatment (first-stage polymerization) according to a conventional method, a polymerization initiator and a polymerizable monomer are added to this dispersion, and this system is polymerized (second-stage polymerization).

Furthermore, the emulsion polymerization aggregation method can also produce toner particles having a core-shell structure.
Specifically, toner particles having a core-shell structure are first prepared by aggregating, associating, and fusing binder resin particles and colorant particles for the core particles.
Next, binder resin particles for the shell layer are added to the dispersion of core particles, and the binder resin particles for the shell layer are aggregated and fused to the surface of the core particles to form a shell layer that covers the surface of the core particles.

An example of the method for producing the toner of the present invention using a pulverization method will be described below.
(1) A step of mixing a binder resin, a colorant, and, if necessary, internal additives using a Henschel mixer or the like. (2) A step of kneading the resulting mixture while heating using an extrusion kneader or the like. (3) A step of roughly pulverizing the resulting kneaded product using a hammer mill or the like, and then further pulverizing using a turbo mill pulverizer or the like. (4) A step of classifying the resulting pulverized product into fine particles using, for example, an air classifier that utilizes the Coanda effect, to form toner base particles. (5) A step of adding external additives to the toner base particles.

Note that the embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit of the present invention.

5. Developer The toner for developing electrostatic images of the present invention can be used as a magnetic or non-magnetic one-component developer, but may also be mixed with a carrier and used as a two-component developer.
When the toner is used as a two-component developer, magnetic particles made of conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the carrier, and ferrite particles are particularly preferred.

The carrier may be a coated carrier in which the surface of magnetic particles is coated with a coating agent such as resin, or a dispersion type carrier in which magnetic powder is dispersed in a binder resin.
The volume-based median diameter (d ₅₀ ) of the carrier is preferably in the range of 20 to 100 μm, and more preferably in the range of 25 to 80 μm.
The volume-based median diameter (d ₅₀ ) of the carrier can be measured, for example, by a laser diffraction particle size distribution measuring device HELOS (manufactured by SYMPATEC) equipped with a wet disperser.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass."

A. Preparation of crystalline resin particle dispersion (A.1) Preparation of crystalline resin [Preparation of crystalline resin (1a)]
The following raw material monomer (1a-1) for an addition polymerization resin (styrene-acrylic resin) segment containing a bireactive monomer and 4 parts by mass of di-t-butyl peroxide as a radical polymerization initiator were placed in a dropping funnel.

<Starting Material Monomer (1a-1)>
Styrene 20.0 parts by mass n-butyl acrylate 8 parts by mass acrylic acid 1.75 parts by mass

Furthermore, the raw material monomer (1a-2) for the polycondensation resin (crystalline polyester resin) segment below was placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve.

<Raw Material Monomer (1a-2)>
Sebacic acid (acid) 412.6 parts by mass 1,6-hexanediol (alcohol) 152.6 parts by mass

Next, the above monomers (1a-1) and (1a-2) were placed in a reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube, and the atmosphere in the reaction vessel was replaced with dry nitrogen gas to obtain a mixed liquid.

0.4 parts by mass of Ti(O-n-Bu) ₄ was added to the resulting mixture, and the mixture was heated to 235°C and reacted under normal pressure (101.3 kPa) for 5 hours. Then, the mixture was further reacted under reduced pressure (8 kPa) for 1 hour.
A reaction mixture was obtained by reacting for a certain period of time.

The resulting reaction solution was cooled to 200°C and then reacted under reduced pressure (20 kPa) until the acid value, calculated using the above-mentioned measurement method, reached 20.0 mgKOH/g, thereby producing crystalline resin (1a).

[Preparation of crystalline resin (2a)]
The following raw material monomer (2a-1) for an addition polymerization resin (styrene-acrylic resin) segment containing a bireactive monomer and 4 parts by mass of di-t-butyl peroxide as a radical polymerization initiator were placed in a dropping funnel.

<Raw Material Monomer (2a-1)>
Styrene 20.0 parts by mass n-butyl acrylate 8 parts by mass acrylic acid 1.75 parts by mass

Furthermore, the raw material monomer (2a-2) for the polycondensation resin (crystalline polyester resin) unit below was placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve.

<Raw Material Monomer (2a-2)>
Tetradecanoic acid (acid) 412.6 parts by mass 1,4-butanediol (alcohol) 152.6 parts by mass

Next, the above monomers (2a-1) and (2a-2) were placed in a reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube, and the atmosphere in the reaction vessel was replaced with dry nitrogen gas to obtain a mixed liquid.

To the resulting mixture, 0.4 parts by mass of Ti(O-n-Bu) ₄ was added, the temperature was raised to 235°C, and the mixture was reacted for 5 hours under normal pressure (101.3 kPa), and then further reacted for 1 hour under reduced pressure (8 kPa) to obtain a reaction solution.

The resulting reaction solution was cooled to 200°C and then reacted under reduced pressure (20 kPa) until the acid value, calculated using the aforementioned measurement method, reached 20.0 mgKOH/g.

[Preparation of crystalline resin (3a)]
The following raw material monomer (3a-1) of the addition polymerization resin (styrene-acrylic resin) unit containing a bireactive monomer and 4 parts by mass of di-t-butyl peroxide as a radical polymerization initiator were placed in a dropping funnel.

<Raw Material Monomer (3a-1)>
Styrene 20.0 parts by mass n-butyl acrylate 8 parts by mass acrylic acid 1.75 parts by mass

Furthermore, the raw material monomer (3a-2) for the polycondensation resin (crystalline polyester resin) unit below was placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve.

<Raw Material Monomer (3a-2)>
Sebacic acid (acid) 412.6 parts by mass 1,12-dodecanediol (alcohol) 152.6 parts by mass

Next, the above monomers (3a-1) and (3a-2) were placed in a reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube, and the atmosphere in the reaction vessel was replaced with dry nitrogen gas to obtain a mixed liquid.

To the resulting mixture, 0.4 parts by mass of Ti(OBu) ₄ was added, and the mixture was heated to 235° C. and reacted at normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour to obtain a reaction solution.
The resulting reaction solution was cooled to 200° C., and then the reaction was carried out under reduced pressure (20 kPa) until the acid value calculated by the above-mentioned measurement method reached 20.0 mgKOH/g.

[Preparation of crystalline resin (4a)]
A reaction vessel equipped with a stirrer, a thermometer, a condenser and a nitrogen gas inlet tube was charged with the following raw material monomer (4a-1) of a polycondensation resin (crystalline polyester resin) unit, and the atmosphere in the reaction vessel was replaced with dry nitrogen gas.

<Raw Material Monomer (4a-1)>
Tetradecanedioic acid (acid) 280 parts by mass 1,4-butanediol (alcohol) 105 parts by mass

To the resulting mixture, 0.4 parts by mass of Ti(O-n-Bu) ₄ was added, the temperature was raised to 235°C, and the mixture was reacted for 5 hours under normal pressure (101.3 kPa), and then further reacted for 1 hour under reduced pressure (8 kPa) to obtain a reaction solution.

The resulting reaction solution was cooled to 200°C and then reacted under reduced pressure (20 kPa) until the acid value, calculated using the aforementioned measurement method, reached 21.4 mgKOH/g.

Next, the pressure in the reaction vessel was gradually released to return to normal pressure, and then 20.3 parts by mass of stearic acid was added as a crystal nucleating agent, followed by reaction at 200° C. for 1.5 hours under normal pressure.
Thereafter, the reaction vessel was depressurized to 5 kPa or less at 200° C., and the mixture was reacted for 2.5 hours to obtain a crystalline resin (4a).
The crystalline resin (4a) had an acid value of 21.4 mgKOH/g.

[Preparation of crystalline resin (5a)]
The raw material monomer (5a-1) of the polycondensation resin (crystalline polyester resin) unit shown below was placed in a reaction vessel equipped with a stirrer, a thermometer, a condenser and a nitrogen gas inlet tube, and the atmosphere in the reaction vessel was replaced with dry nitrogen gas.

<Raw Material Monomer (5a-1)>
Sebacic acid (acid) 280 parts by mass 1,6-hexanediol (alcohol) 105 parts by mass 1,4-butanediol (alcohol) 105 parts by mass

To the resulting mixture, 0.4 parts by mass of Ti(O-n-Bu) ₄ was added, the temperature was raised to 235°C, and the mixture was reacted for 5 hours under normal pressure (101.3 kPa), and then further reacted for 1 hour under reduced pressure (8 kPa) to obtain a reaction solution.

The resulting reaction solution was cooled to 200° C., and then the reaction was carried out under reduced pressure (20 kPa) until the acid value calculated by the above-mentioned measurement method reached 21.4 mgKOH/g.

Next, the pressure in the reaction vessel was gradually released to return to normal pressure, and then 20.3 parts by mass of stearic acid was added as a crystal nucleating agent, followed by reaction at 200° C. for 1.5 hours under normal pressure.
Thereafter, the pressure in the reaction vessel was reduced to 5 kPa or less at 200° C., and the mixture was reacted for 2.5 hours to obtain a crystalline resin (5a).
The crystalline resin (5a) had an acid value of 21.4 mgKOH/g.

(A.2) Preparation of Crystalline Resin Particle Dispersion [Preparation of Crystalline Resin Particle Dispersion (1A)]
174.3 parts by mass of crystalline resin (1a) and 102 parts by mass of methyl ethyl ketone were placed in a reaction vessel, stirred at 75°C for 30 minutes to dissolve, and 3.1 parts by mass of a 25% by mass aqueous sodium hydroxide solution was added to obtain a solution.

The above solution was placed in a reaction vessel equipped with a stirrer, and 375 parts by mass of water heated to 70° C. was added dropwise to the solution over a period of 70 minutes while stirring.
During the dropping, the liquid in the container became cloudy, and after the entire amount was dropped, a uniformly emulsified liquid (1a) was obtained.

While the above emulsion was kept at 70°C, the pressure was reduced to 15 kPa (150 mbar) using a diaphragm vacuum pump "V-700" (manufactured by Buchi), and the mixture was stirred for 3 hours to distill off methyl ethyl ketone.
Thereafter, the mixture was cooled at a cooling rate of 6° C./min to prepare a crystalline resin particle dispersion (1A) in which particles of the crystalline resin (1a) were dispersed.

The volume average particle size of the crystalline resin (1a) in the crystalline resin microparticle dispersion (1A) was measured using a particle size distribution analyzer (laser diffraction particle size distribution analyzer "LA-750 (manufactured by HORIBA)"), and the volume average particle size of the crystalline resin (1a) was found to be 202 nm.

[Preparation of crystalline resin fine particle dispersions (2A) to (5A)]
Crystalline resin particle dispersions (2A) to (5A) were prepared in the same manner as in the preparation of crystalline resin particle dispersion (1A), except that the crystalline resin (1a) was changed to crystalline resins (2a) to (5a), respectively.

(A.3) Composition Ratio and Melting Point of Styrene-Acrylic Modified Crystalline Polyester Table 1 shows the composition ratio and melting point of the styrene-acrylic modified crystalline polyester in the crystalline resin particle dispersions (1A) to (5A).
The styrene-acrylic-modified crystalline polyester composition ratio in Table I is a value calculated from the total mass (29.75 parts by mass) of the raw material monomer (1a-1) and the total mass (565.2 parts by mass) of the raw material monomer (1a-2) when producing, for example, the crystalline resin (1a), and was calculated similarly for the other crystalline resins (2a) to (5a).
As mentioned above, in the present invention, the above-mentioned "melting point" refers to the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin observed during the first heating process in differential scanning calorimetry, and the "melting point" in Table I refers to the above-mentioned C ₍₁₎ p (°C).

B. Preparation of Amorphous Resin Particle Dispersion [Preparation of Amorphous Resin Particle Dispersion (1)]
(First-stage polymerization)
A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device was charged with 8 parts by mass of sodium dodecyl sulfate and 3,000 parts by mass of ion-exchanged water, and the internal temperature was raised to 80°C while stirring at a stirring speed of 230 rpm under a nitrogen stream.

After the temperature was raised, a solution of 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water was added, the liquid temperature was again brought to 80°C, and a mixed liquid of the following raw material monomer (1b-1) was added dropwise over 1 hour.

<Raw Material Monomer (1b-1)>
Styrene 480.0 parts by mass n-butyl acrylate 250.0 parts by mass Methacrylic acid 68.0 parts by mass

After the mixture was added dropwise, the mixture was heated and stirred at 80°C for 2 hours to polymerize the raw material monomer (1b-1), thereby preparing a vinyl resin microparticle dispersion (S1) as the first-stage polymerization liquid.

(Second-stage polymerization)
A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device was charged with 1,100 parts by mass of ion-exchanged water and 289 parts by mass of the vinyl resin microparticle dispersion (S1) (first-stage polymerization liquid) prepared by the first-stage polymerization, and heated to 87°C.

Thereafter, a mixture obtained by dissolving the following raw material monomer (1b-2), a chain transfer agent, and a release agent at 85°C was subjected to a mixing and dispersion treatment for 10 minutes using a mechanical disperser CLEARMIX (manufactured by M Technique Co., Ltd.) having a circulation path, to prepare a dispersion containing emulsified particles (oil droplets).
The above dispersion was added to the 5 L reaction vessel, and a polymerization initiator solution prepared by dissolving 5.5 parts by mass of potassium persulfate in 103 parts by mass of ion-exchanged water was added. The system was heated and stirred at 87°C for 1 hour to carry out polymerization, thereby preparing a vinyl resin microparticle dispersion (S1').

<Raw Material Monomer (1b-2)>
Styrene 253 parts by mass 2-ethylhexyl acrylate 107.3 parts by mass Methacrylic acid 39.2 parts by mass

<Chain transfer agent>
n-Octyl-3-mercaptopropionate 4.45 parts by mass

<Release Agent>
Behenic acid behenate 120.0 parts by mass

(Third-stage polymerization)
To the vinyl resin particle dispersion (S1') obtained by the second-stage polymerization, a solution prepared by dissolving 7.4 parts by mass of potassium persulfate in 157.9 parts by mass of ion-exchanged water was added.

Furthermore, a mixture of the following raw material monomer (1b-3) and chain transfer agent was added dropwise over 90 minutes at a temperature of 84°C.

<Raw Material Monomer (1b-3)>
Styrene 335.0 parts by mass n-Butyl acrylate 211.0 parts by mass Methacrylic acid 44.0 parts by mass n-Octyl-3-mercaptopropionate 8.1 parts by mass

After the dropwise addition was completed, polymerization was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28°C to obtain amorphous resin microparticle dispersion (1).

[Preparation of Amorphous Resin Particle Dispersions (2) to (12)]
A vinyl resin particle dispersion (S1) was prepared in the same manner as in the preparation of the amorphous resin particle dispersion (1) up to the first polymerization stage.
The second-stage polymerization and subsequent steps were carried out in the same manner as in the preparation of resin fine particle dispersion (1), except that the raw material monomers, chain transfer agent, and release agent were changed to 289 parts by mass of the first-stage polymerization liquid as shown in Table II, to prepare resin fine particle dispersions (2) to (12).

C. Preparation of Colorant Particle Dispersion Liquid 226 parts by mass of sodium dodecyl sulfate was added to 1,600 parts by mass of ion-exchanged water, and while stirring the solution, 420 parts by mass of copper phthalocyanine (C.I. Pigment Blue 15:3) was gradually added thereto.

A colorant particle dispersion (P1) was prepared by dispersing using a Clearmix stirring device (manufactured by M Technique Co., Ltd., "Clearmix" is a registered trademark of the company).

The volume-based median diameter of the colorant particles in the colorant particle dispersion (P1) was measured and found to be 110 nm.

D. Preparation of each toner (D.1) Toner (1)
(D.1.1) Preparation of Toner Particles (1) Into a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, 480 parts by mass (solid content equivalent) of the amorphous resin fine particle dispersion (1) and 350 parts by mass of ion-exchanged water were placed.

At room temperature (25° C.), a 5 mol/L aqueous solution of sodium hydroxide was added to adjust the pH to 10.
Further, 36.4 parts by mass (solid content equivalent) of colorant particle dispersion (P1) was added, and 80 parts by mass of a 50% by mass aqueous magnesium chloride solution was added thereto at 30° C. over 10 minutes with stirring to obtain a dispersion.

The resulting dispersion was allowed to stand for 5 minutes, then heated to 82°C over 60 minutes. After reaching 82°C, 59.3 parts by mass (solids content equivalent) of crystalline resin microparticle dispersion (1A) was added over 20 minutes. The stirring speed was adjusted so that the particle size growth rate was 0.01 μm/min, and the particles were allowed to grow until the volume-based median diameter, as measured using a Coulter Multisizer 3 (manufactured by Coulter Beckman, Inc.), reached 6.0 μm.

Next, an aqueous solution prepared by dissolving 80 parts by mass of sodium chloride in 300 parts by mass of ion-exchanged water was added to stop the growth of particle size.
Next, the mixture was stirred at 82°C to allow the particles to fuse together until the average circularity of the toner particles reached 0.970, and then cooled at a rate of 0.5°C/min or more to lower the liquid temperature to 30°C or lower.
Next, solid-liquid separation was carried out, and the dehydrated toner cake was re-dispersed in ion-exchanged water, and the solid-liquid separation operation was repeated three times for washing.
After washing, the particles were dried at 35° C. for 24 hours to prepare toner particles (1).

(D.1.2) Preparation of Toner (1) 100 parts by mass of the obtained toner particles (1), 0.6 part by mass of hydrophobic silica particles (number average primary particle size: 12 nm, hydrophobicity: 68), 1.0 part by mass of hydrophobic titanium oxide particles (number average primary particle size: 20 nm, hydrophobicity: 63), and 1.0 part by mass of sol-gel silica (number average primary particle size=110 nm) were mixed in a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd.) at a rotor peripheral speed of 35 mm/sec and at 32° C. for 20 minutes.
After mixing, coarse particles were removed using a sieve with 45 μm openings to obtain toner (1).

(D.1.3) Preparation of Two-Component Developer Toner (1) and acrylic resin-coated ferrite carrier having a volume average particle size of 32 μm were added and mixed so that the concentration of toner (1) was 6% by mass.
Through the above steps, a two-component developer containing the toner (1) was prepared.

(D.2) Toners (2), (3), (5) to (11), (13) to (18)
Toners (2), (3), (5) to (11), and (13) to (18) and two-component developers containing them were prepared in the same manner as in the preparation of toner (1) and a two-component developer containing it, except that the compositional ratios of the resin particle dispersion, the crystalline resin particle dispersion, and the amorphous resin and the crystalline resin were changed as shown in Table III.

(D.3) Toner (4)
(D.3.1) Preparation of Amorphous Polyester Resin (1b) A mixed liquid containing the following raw material monomer (1b-1) for the vinyl resin, a raw material monomer having a substituent reactive with both the amorphous polyester resin and the vinyl resin, and 16.0 parts by mass of di-t-butyl peroxide as a polymerization initiator was placed in a dropping funnel.

<Raw Material Monomer (1b-1)>
Styrene 80.0 parts by mass n-butyl acrylate 20.0 parts by mass

<Raw material monomer having a substituent that reacts with both amorphous polyester resin and vinyl resin>
Acrylic acid 10.0 parts by mass

Furthermore, the raw material monomer (1b-2) for the amorphous polyester resin below was placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve.

<Raw Material Monomer (1b-2)>
Bisphenol A ethylene oxide 2-mol adduct 50.2 parts by mass Bisphenol A propylene oxide 2-mol adduct 249.8 parts by mass Terephthalic acid 120.1 parts by mass Dodecenyl succinic acid 46.0 parts by mass

While stirring, the mixture in the dropping funnel was added dropwise to the four-neck flask over 90 minutes, and after aging for 60 minutes, the unreacted raw material monomer was removed under reduced pressure (8 kPa).

Thereafter, 0.4 parts by mass of Ti(OBu) ₄ was added as an esterification catalyst, the temperature was raised to 235°C, and the reaction was carried out under normal pressure (101.3 kPa) for 5 hours, and then under reduced pressure (8 kPa) for 1 hour.

The mixture was then cooled to 200° C. and reacted under reduced pressure (20 kPa), followed by solvent removal treatment to prepare an amorphous polyester resin (1b).
The resulting amorphous polyester resin (1b) had a weight average molecular weight (Mw) of 24,000 and an acid value of 18.2 mgKOH/g.

(D.3.2) Preparation of Amorphous Polyester Resin Microparticle Dispersion (1B) 108 parts by mass of the obtained amorphous polyester resin (1b) and 64 parts by mass of methyl ethyl ketone were placed in a reaction vessel and stirred at 70°C for 30 minutes to dissolve, thereby obtaining a solution.

To the above solution, 3.4 parts by mass of a 25% by mass aqueous solution of sodium hydroxide was added, and the mixture was placed in a reaction vessel equipped with a stirrer. While stirring, 210 parts by mass of water heated to 70°C was added dropwise over 70 minutes.
During the dropping, the liquid in the container became cloudy, and after the entire amount was dropped, a uniformly emulsified liquid was obtained.

The particle size of the oil droplets in the emulsion was measured using a laser diffraction particle size distribution analyzer, LA-750 (HORI
As a result of measurement using a particle size analyzer manufactured by BA, the volume average particle size was found to be 90 nm.

Next, while keeping the emulsion at 70°C, the emulsion was stirred for 3 hours under a reduced pressure of 15 kPa (150 mbar) using a diaphragm vacuum pump "V-700" (manufactured by Buchi Corporation) to distill off the methyl ethyl ketone and prepare amorphous polyester resin microparticle dispersion (1B).

As a result of measurement using the particle size distribution measuring device, the volume average particle size of the amorphous polyester resin (1b) in the amorphous polyester resin microparticle dispersion (1B) was 94 nm.

(D.3.3) Preparation of Toner Particles (4) 486 parts by mass (solid content equivalent) of the resin particle dispersion (6) and 350 parts by mass of ion-exchanged water were placed in a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube.
At room temperature (25° C.), a 5 mol/L aqueous solution of sodium hydroxide was added to adjust the pH to 10.

Furthermore, 36.4 parts by weight (solids content equivalent) of colorant particle dispersion (P1) was added, and 80 parts by weight of a 50% by weight aqueous magnesium chloride solution was added over 10 minutes at 30°C while stirring to obtain a dispersion.

The resulting dispersion was allowed to stand for 5 minutes, then heated to 82°C over 60 minutes. After reaching 82°C, 54 parts by mass (solids content equivalent) of crystalline resin microparticle dispersion (2A) was added over 20 minutes, and the stirring speed was adjusted so that the particle size growth rate was 0.01 μm/min. The particles were allowed to grow until the volume-based median diameter, measured using a Coulter Multisizer 3 (manufactured by Coulter Beckman, Inc.), reached 6.0 μm.

Next, 60 parts by weight (solids equivalent) of amorphous polyester resin microparticle dispersion (1B) was added over 30 minutes, and when the supernatant of the reaction solution became transparent, an aqueous solution of 80 parts by weight of sodium chloride dissolved in 300 parts by weight of ion-exchanged water was added to stop the growth of particle size.

The mixture was then stirred at 82°C to allow the particles to fuse together until the average circularity of the toner particles reached 0.970, after which it was cooled at a rate of 0.5°C/min or more to lower the liquid temperature to 30°C or below.

Next, solid-liquid separation was carried out, and the dehydrated toner cake was re-dispersed in ion-exchanged water, and the solid-liquid separation operation was repeated three times for washing.
After washing, the particles were dried at 35° C. for 24 hours to prepare toner particles (4).

(D.3.4) Preparation of Toner (4) To 100 parts by mass of the obtained toner particles (4), 0.6 parts by mass of hydrophobic silica particles (number average primary particle size: 12 nm, hydrophobicity: 68), 1.0 part by mass of hydrophobic titanium oxide particles (number average primary particle size: 20 nm, hydrophobicity: 63), and 1.0 part by mass of sol-gel silica (number average primary particle size=110 nm) were added, and mixed using a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd.) at a rotor peripheral speed of 35 mm/sec and 32° C. for 20 minutes.
After mixing, coarse particles were removed using a sieve with 45 μm openings to prepare toner (4).

(D.3.5) Preparation of Two-Component Developer Toner (4) and acrylic resin-coated ferrite carrier having a volume average particle size of 32 μm were added and mixed so that the toner particle concentration was 6% by mass.
Through the above steps, a two-component developer containing the toner (4) was prepared.

(D.4) Toner (12)
(D.4.1) Preparation of release agent particle dispersion (W1)

FNP-0090 (mold release agent, melting point 89°C) 100 parts by weight Anionic surfactant (Neogen RK manufactured by Daiichi Kogyo Seiyaku) 10 parts by weight Ion-exchanged water 400 parts by weight

The above materials were mixed and heated to 80° C., and thoroughly dispersed using an Ultra Turrax T50 manufactured by IKA.
Thereafter, the mixture was subjected to a dispersion treatment using a pressure discharge type Gaulin homogenizer, and then ion-exchanged water was added to the dispersion to adjust the solid content to 15%, thereby preparing a release agent particle dispersion (W1).
The volume-based median diameter of the release agent particles in this dispersion was measured using a laser diffraction particle size distribution analyzer LA-750 (manufactured by HORIBA) and was found to be 220 nm.

(D.4.2) Preparation of Toner Particles (12) Into a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, 340.81 parts by mass (in terms of solid content) of the amorphous polyester resin dispersion (1B), 48.44 parts by mass (in terms of solid content) of the release agent dispersion (W1), and 2,000 parts by mass of ion-exchanged water were placed.

At room temperature (25° C.), a 5 mol/L aqueous solution of sodium hydroxide was added to adjust the pH to 10.
Further, 7 parts by mass (solid content equivalent) of colorant particle dispersion (P1) was added, and a solution of 60 parts by mass of magnesium chloride dissolved in 60 parts by mass of ion-exchanged water was added thereto at 30° C. over 10 minutes while stirring.

After leaving it for 3 minutes, the temperature was raised to 80°C over 60 minutes. Once the temperature reached 80°C, 43.25 parts by mass (solids content equivalent) of crystalline resin microparticle dispersion (5A) was added over 20 minutes, and the stirring speed was adjusted so that the particle size growth rate was 0.01 μm/min. The particles were allowed to grow until the volume-based median diameter, measured using a Coulter Multisizer 3 (manufactured by Coulter Beckman, Inc.), reached 6.0 μm.

Next, an aqueous solution of 190 parts by weight of sodium chloride dissolved in 760 parts by weight of ion-exchanged water was added to stop the growth of particle size.

The mixture was then heated to 80°C and stirred to allow the particles to fuse together until the average circularity of the toner particles reached 0.970, after which it was cooled to a liquid temperature of 30°C or below.

Thereafter, the temperature was raised to 50° C. over 30 minutes while stirring, and a heat treatment step was carried out for 3 hours.
Thereafter, the liquid temperature was lowered to 30°C or below by cooling.

Next, solid-liquid separation was carried out, and the dehydrated toner cake was re-dispersed in ion-exchanged water, and the solid-liquid separation operation was repeated three times for washing.
After washing, the particles were dried at 40° C. for 24 hours to obtain toner particles (12).

(D.4.3) Preparation of toner (12) 100 parts by mass of the obtained toner particles (12), 0.6 parts by mass of hydrophobic silica particles (number average primary particle size: 12 nm, hydrophobicity: 68), 0.6 parts by mass of hydrophobic titanium oxide particles (number average primary particle size: 2
1.0 part by mass of sol-gel silica (number average primary particle diameter = 110 nm, hydrophobicity: 63) and 1.0 part by mass of sol-gel silica (number average primary particle diameter = 110 nm) were added, and mixed using a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd.) at a rotor circumferential speed of 35 mm/sec and 32°C for 20 minutes.
Thereafter, coarse particles were removed using a sieve with 45 μm openings to prepare toner (12).

(D.4.4) Preparation of Two-Component Developer Toner (12) and an acrylic resin-coated ferrite carrier having a volume average particle size of 32 μm were added and mixed so that the toner particle concentration was 6% by mass.
Through the above steps, a two-component developer containing toner (12) was prepared.

E. Examples , Reference Examples and Comparative Examples The types of dispersion liquids of amorphous resins and crystalline resins in Toner Nos. (1) to (18) are as shown in Table III.
The evaluation results shown in Table IV were obtained using each of the release agents, crystalline resins and toners shown in Table III.
The evaluation methods and criteria for each are shown below.

(Measurement of thermal properties of each release agent and crystalline resin by differential scanning calorimetry)
The thermal properties of each release agent and crystalline resin were measured by differential scanning calorimetry according to the following procedure.

Five mg of the sample to be measured (each release agent and crystalline resin) was sealed in an aluminum pan KIT NO. B0143013 and set in the sample holder of a thermal analyzer "Diamond DSC (manufactured by PerkinElmer)." During the first heating (heating process), the temperature was raised from 0°C to 100°C at a heating rate of 10°C/min and held at 100°C for one minute. In the endothermic curve obtained at this time, the endothermic peak temperature W ₍₁₎ p (°C) derived from each release agent and the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin were measured.
Thereafter, the temperature was lowered from 100° C. to 0° C. at a rate of 10° C./min, and the temperature was maintained at 0° C. for 1 minute.
Then, during the second heating (temperature rising process), the temperature was raised from 0° C. to 100° C. at a temperature rising rate of 10° C./min and held at 100° C. for 1 minute.
An empty aluminum pan was used as a reference.

(Measurement of softening point temperature using a thermal flow evaluation device)
Using a flow tester CFT-500D (manufactured by Shimadzu Corporation), a 1 ^cm3 sample was heated at a temperature increase rate of 6°C/min, while a pressure load of 20 kg/ ^cm2 was applied with a plunger (also referred to as a "piston") so as to push out a nozzle with a diameter of 1 mm and a length of 1 mm. In this way, a plunger descending amount (flow value)-temperature curve (also referred to as a "softening flow curve") was drawn, and when the height of the S-shaped curve is taken as h, the temperature corresponding to h/2 (the temperature at which half of the toner has flowed out) was taken as the softening point temperature Tf1 _/2 (also referred to as the "1/2 method softening point").

(E.1) Toner Manufacturability After producing the toners (1) to (18) in the Examples , Reference Examples , and Comparative Examples, whether or not the toners had been produced to the desired particle size and circularity was confirmed by observing the surfaces of the toner particles using the method described below, and the manufacturability of the toners was evaluated according to the evaluation criteria described below.

(Method for observing the surface of toner particles)
Toner particles, a small amount of neutral detergent, and pure water are added to a beaker and mixed well, and the mixture is filtered through a 1 μm mesh three times to remove the external additive particles and expose the surfaces of the toner base particles.
Thereafter, the toner is fixed in one layer with carbon tape on a specimen stage for electron microscope observation.
The toner was measured and photographed under the following conditions using a transmission electron microscope "JSM-7401F" (manufactured by JEOL Ltd.), and it was determined whether or not the crystalline material had bled out from the toner.

〔conditions〕
Measurement mode: SE mode, LEI
Acceleration voltage: 1.0 kV
Emission Current: 20μA
Working distance: 8mm
Magnification: ×10000
Datasize: 1280×1024

(Evaluation criteria)
〇 No bleeding of crystalline materials occurs and production can be carried out without any problems.
△ Although there is some bleeding of the crystalline material, production is possible without any problems.
× Bleeding of crystalline material occurs, and the desired particle size and circularity are not achieved, which poses manufacturing issues.

(E.2) Evaluation of Low-Temperature Fixing Property As an image forming apparatus, a commercially available full-color multifunction printer "AccurioPress C3080 (manufactured by Konica Minolta)" modified so that the surface temperatures of the upper fixing belt and the lower fixing roller could be changed was used, and the two-component developers of the above colors were loaded sequentially.
A test was conducted in which a solid image with a toner adhesion amount of 11.3 g/m ² was printed on A4 plain paper (basis weight 90 g/m ² ) at a fixing temperature of 100 to 200° C., and the fixing temperature was changed in 5° C. increments.
The lowest fixing temperature at which image staining due to fixing offset was not visually confirmed was taken as the lowest fixing temperature, and the low-temperature fixability was evaluated according to the following evaluation criteria.

(Evaluation criteria)
⊚: The minimum fixing temperature is less than 135° C. (the low-temperature fixing property of the toner is extremely good).
The minimum fixing temperature is 135° C. or higher and lower than 145° C. (good low-temperature fixing property of the toner).
△: The minimum fixing temperature is 145° C. or higher and lower than 155° C. (good low-temperature fixing property of the toner).
× Minimum fixing temperature: 155°C or higher (the toner has poor low-temperature fixing ability and cannot be used).

(E.3) Evaluation of Fixing Separation Property As an image forming apparatus, a commercially available color multifunction printer AccurioPress C3080 (manufactured by Konica Minolta) was used, which was modified so that the surface temperatures of the upper fixing belt and the lower fixing roller could be changed, and the two-component developers of the above colors were sequentially loaded.
The above-mentioned device was modified so that the fixing temperature, toner adhesion amount, and system speed could be freely set.
The paper used for evaluation was OK Topcoat+85 g/m ² (manufactured by Oji Paper Co., Ltd.).
The temperature of the upper fixing belt was set to a temperature (U.O. avoidance temperature + 25°C) 25°C higher than the temperature at which under-offset does not occur (U.O. avoidance temperature), and the lower fixing roller was set to 90°C.The leading edge margin amount was varied for each full solid image (adhesion amount 8.0 g/ ^m2 ) and the leading edge margin amount immediately before a paper jam occurred was used as a measure of thin paper separation performance.
The smaller the value of the separable leading edge margin, the better the separation performance.
The evaluation was carried out in a normal temperature and humidity environment (NN environment: 25° C., 50% RH).
Furthermore, the smaller the separable leading edge margin, the better the thin paper separability.

(Evaluation criteria)
⊚: The amount of separable leading edge margin is 0 mm or more and 2 mm or less.
◯: The amount of separable leading edge margin is greater than 2 mm and equal to or less than 4 mm.
△: The amount of separable leading edge margin is greater than 4 mm and is 6 mm or less.
x: The amount of separable leading edge margin is greater than 6 mm.

(E.4) Evaluation of Release Agent Adhesion A commercially available color multifunction printer, AccurioPress C3080 (manufactured by Konica Minolta, Inc.), was modified so that the surface temperature of the upper fixing belt could be changed within a range of 140 to 220°C, and the surface temperature of the lower fixing roller could be changed within a range of 120 to 200°C.
Each developer was loaded into this modified machine in turn, and a solid image with a toner adhesion amount of 8.0 g/m ² was formed on A4 (basis weight 157 g/m ² ) gloss coated paper in an environment of normal temperature and humidity (temperature 20°C, humidity 50% RH), and then fixed.
The fixing speed during the fixing process was 460 mm/sec, and the fixing temperature (surface temperature of the upper fixing belt) was set to the under-offset temperature + 35°C.

After printing 100 sheets, the wax adhesion condition on the transport roller was visually evaluated on a 10-point scale according to the following evaluation criteria, with a rank of 5 or higher being considered a pass.

(Evaluation criteria)
Rank 10 to 9: No wax adhesion was observed (passed).
Rank 8 to 7: Some wax adhesion is observed, but it is not a quality problem (pass).
Rank 6 to 5: Wax adhesion is observed, but it is still usable (passed).
Rank 4 to 1: Wax adhesion was confirmed and the level was not practical (failed).

(E.5) Gloss Unevenness A commercially available color multifunction printer, AccurioPress C3080 (manufactured by Konica Minolta, Inc.), was modified so that the pressure in the nip region of the fixing device and the surface temperature of the fixing heat roller (fixing roller) could be changed within a range of 100 to 210°C, and so that the process speed (nip time) could be changed, and developers produced from each toner were loaded therein.

For each developer manufactured from the toner, a fixing experiment was conducted in an environment of normal temperature and humidity (temperature 20°C, humidity 50% RH) to output a gloss memory evaluation image (alphabet output image) with a toner adhesion amount of 8 g/ ^m2 onto A3-size coated paper Esprit C 209 g/ ^m2 (manufactured by Nippon Paper Industries Co., Ltd.) under conditions of a fixing unit nip pressure of 238 kPa and a nip time of 25 milliseconds (process speed 480 mm/s), while repeatedly changing the set fixing temperature from 160°C to 200°C in increments of 10°C.
The gloss unevenness was evaluated according to the following evaluation criteria.
It should be noted that if the evaluation criteria below are rated as "○", the product is suitable for practical use.

(Evaluation criteria)
◯: No uneven gloss occurs (practical).
×: Gloss unevenness occurs (not practical).

(E.6) Evaluation of varnish wetting In a commercially available color multifunction printer AccurioPress C3080 (manufactured by Konica Minolta), coated paper of 157 g/ ^m2 was selected as the paper type, and each developer was loaded sequentially. A solid image with a toner adhesion amount of 8.0 g/ ^m2 was formed on A4 (basis weight 157 g/ ^m2 ) gloss coated paper in an environment of normal temperature and humidity (temperature 20°C, humidity 50% RH), and then fixed.
A varnish coater (Digi UV Coater manufactured by BN Technologies) was used on this image, and the coating conditions were set to a speed of 30 m/min and a coating thickness of approximately 5 μm. UV Clear manufactured by Sakata Inx Corporation was used as the varnish to form an image with a varnish layer.
The varnish layer of each of the obtained evaluation images was visually observed, and the wettability of the varnish was evaluated according to the following evaluation criteria.

(Evaluation criteria)
◎ Zero 0.1mm pinholes in each 10cm x 10cm area.
〇 There are no more than two pinholes of 0.1 mm in size in each 10 cm x 10 cm area.
△ There are 3 to 10 pinholes of 0.1 mm in size in each 10 cm x 10 cm area.
× 10cm × 10cm, there are 11 or fewer pinholes of 0.1mm in size or pinholes of 0.1mm or larger.

[summary]
From the above, it can be seen that the Examples are superior overall to the Comparative Examples in the evaluation results of toner production efficiency, low-temperature fixability, fixation separation property, release agent adhesion, gloss unevenness and varnish coating property.

Claims (8)

A toner for developing electrostatic images, comprising toner base particles containing at least a binder resin and a release agent,
The binder resin contains at least a crystalline resin,
When the endothermic peak temperature derived from the release agent observed during the first temperature rise in differential scanning calorimetry of the electrostatic image developing toner is defined as W ₍₁₎ p (°C), the endothermic peak temperature of the crystalline resin is defined as C ₍₁₎ p (°C), and the softening point temperature measured by a thermal flow evaluation device is defined as Tf _1/2 (°C),
90≦Tf _1/2 (° C.)≦115
82≦W ₍₁₎ p(℃)
A toner for developing electrostatic images, characterized in that the relationships represented by the following formulas (1a) and (2a) are satisfied.
14 ≦W ₍₁₎ p−C ₍₁₎ p≦ 17 (1a)
5≦Tf _1/2 -W ₍₁₎ p≦36 (2a) 2. The toner for developing electrostatic images according to claim 1, wherein the softening point temperature Tf _1/2 (°C) measured by the thermal flow evaluation device and the endothermic peak temperature C ₍₁₎ p (°C) of the crystalline resin observed during the first temperature rise process in the differential scanning calorimetry satisfy the relationship represented by the following formula (3):
Tf _1/2 -C ₍₁₎ p≦48 (3) 3. The toner for developing electrostatic images according to claim 1, wherein the softening point temperature Tf _1/2 (°C) measured by the thermal flow evaluation device and the endothermic peak temperature W ₍₁₎ p (°C) attributable to the release agent observed during a first temperature rise in the differential scanning calorimetry satisfy the relationship represented by the following formula ( 2b ):
11≦Tf _1/2 -W ₍₁₎ p≦30 (2b) The toner for developing electrostatic images according to any one of claims 1 to 3 , wherein the endothermic peak temperature Wp ₍₁₎ (°C) derived from the release agent is within a range of 82 to 100 (°C). The toner for developing electrostatic images according to any one of claims 1 to 4 , wherein the crystalline resin contains a crystalline polyester. 6. The toner for developing electrostatic images according to claim 1 , wherein the crystalline resin is a hybrid crystalline polyester resin formed by bonding a crystalline polyester polymer segment and a vinyl resin polymer segment. 7. The toner for developing electrostatic images according to claim 1 , wherein the binder resin contains at least a styrene-acrylic resin. A method for producing the toner for developing electrostatic images according to any one of claims 1 to 7 , comprising the steps of:
1. A method for producing a toner for developing electrostatic images, comprising the steps of: adding a crystalline resin particle dispersion to an amorphous resin particle dispersion; and growing the toner particles at a temperature equal to or higher than the melting point of the crystalline resin.