Toner for electrostatic image development, electrostatic image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method.

Abstract

To provide an electrostatic charge image developing toner which offers low-temperature fixability and a low detachment rate of external additives.SOLUTION: An electrostatic charge image developing toner provided herein comprises: toner parties containing a binder resin containing a crystalline resin and a mold release agent; and an external additive. When defining the volume-average particle diameter of the toner particles as d, the number of domains of the crystalline resin present in a region from a surface to a depth of 0.2d of the toner particle amounts to 30-90%, inclusive, by number with respect to the total number of domains of the crystalline resin.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a toner for electrostatic charge image development, an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method.

Background Art

[0002] Methods for visualizing image information, such as the electrophotographic method, are currently used in various fields. In the electrophotographic method, an electrostatic charge image is formed as image information on the surface of an image carrier by charging and electrostatic charge image formation. Then, a toner image is formed on the surface of the image carrier by a developer containing toner, and after transferring this toner image onto a recording medium, the toner image is fixed to the recording medium. Through these steps, the image information is visualized as an image.

[0003] For example, Patent Document 1 discloses a toner for electrostatic charge image development containing a binder resin, a colorant, a release agent, and a plasticizer, wherein when the average dispersed particle diameter of the domains of the release agent is Dw, the average number of dispersed domains of the release agent is Nw, the average dispersed particle diameter of the domains of the plasticizer is Dc, and the average number of dispersed domains of the plasticizer is Nc, a toner for electrostatic charge image development that satisfies all of the following formulas (1) to (4) is disclosed. Dw / Dc≧3 ··· (1) Nc / Nw≧5 ··· (2) 0.3μm≦Dw≦3.0μm ··· (3) 0.045μm≦Dc≦0.9μm ··· (4)

Prior Art Documents

Patent Documents

[0006] The means for solving the above problems include the following embodiments. <1> The toner particles contain a binder resin containing a crystalline resin and a release agent, and an external additive. A toner for developing electrostatic images, wherein, when the volume-average particle size of the toner particles is d, the number of domains of the crystalline resin present in the region from the surface of the toner particles to a depth of 0.2d is between 30% and 90% of the total number of domains of the crystalline resin.

[0007] <2> The number of domains of the crystalline resin present in the region from the surface of the toner particle to a depth of 0.05d is 2 percent or less of the total number of domains of the crystalline resin. <1> Toner for developing electrostatic images as described above. <3> The number of domains of the release agent located in the region from the surface of the toner particle to a depth of 0.2d or more is 70% or more of the total number of domains of the release agent. <1> or <2> Toner for developing electrostatic images as described above. <4> The domain diameter of the aforementioned release agent is 0.5 μm or more and 1.5 μm or less. <3> Toner for developing electrostatic images as described above. <5> The aspect ratio of the domains of the crystalline resin is 3 or more and 30 or less. <1> ~ <4> A toner for developing electrostatic images, as described in one of the following. <6> The ratio (Y / X) of the aspect ratio Y of the domains of the crystalline resin to the aspect ratio X of the domains of the mold release agent satisfies the relationship 0.2 ≤ Y / X ≤ 30. <1> ~ <5> A toner for developing electrostatic images, as described in one of the following. <7> The electrostatic charge image developing toner according to any one of <1> to <6>, wherein the domain diameter A of the crystalline resin and the domain diameter B of the release agent satisfy the relationship A < B. <8> The electrostatic charge image developing toner according to <7>, wherein the ratio (A / B) of the domain diameter A of the crystalline resin to the domain diameter B of the release agent satisfies the relationship 0.2 ≦ A / B < 1. <9> Toner particles containing a binder resin containing a crystalline resin and a release agent, and an external additive, wherein a domain of the crystalline resin exists within the toner particles, The electrostatic charge image developing toner having a detachment rate of the external additive with respect to the toner particles of less than 50%.

[0008] <10> An electrostatic charge image developer containing the electrostatic charge image developing toner according to any one of <1> to <9>. <11> A toner cartridge that houses the electrostatic charge image developing toner according to any one of <1> to <9> and is detachable from an image forming apparatus. The electrostatic charge image developing toner according to <10>, and a developing unit that develops the electrostatic charge image formed on the surface of the image carrier as a toner image. <12> A process cartridge that houses the electrostatic charge image developer according to <10> and is detachable from an image forming apparatus. The electrostatic charge image developing toner according to <10>, and a developing unit that develops the electrostatic charge image formed on the surface of the image carrier as a toner image. <13> An image carrier, charging means for charging the surface of the image carrier, [[ID=2,7]] electrostatic charge image forming means for forming an electrostatic charge image on the charged surface of the image carrier, <10> An electrostatic charge image developing toner according to <10>, and a developing unit that develops the electrostatic charge image formed on the surface of the image carrier as a toner image. transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, fixing means for fixing the toner image transferred to the surface of the recording medium, An image forming apparatus comprising: <14> A charging step of charging the surface of the image carrier, A step of forming an electrostatic image on the surface of the charged image holder, <10> A developing step in which the electrostatic image formed on the surface of the image holder is developed as a toner image using the electrostatic image developer described above, A transfer step of transferring the toner image formed on the surface of the image holder to the surface of the recording medium, A fixing step for fixing the toner image transferred to the surface of the recording medium, An image forming method having the following characteristics. [Effects of the Invention]

[0009] <1> According to the invention, a toner for developing electrostatic images is provided that has low-temperature fixing properties and a low rate of detachment of the external additive, compared to a case where, when the volume average particle size of the toner particles is d, the number of crystalline resin domains present in the region from the surface of the toner particles to a depth of 0.2d is less than 30% or more than 90% of the total number of crystalline resin domains.

[0010] <2> According to the invention, it is possible to provide a toner for electrostatic image development in which the detachment rate of external additives is lower compared to the case where the number of crystalline resin domains present in the region from the surface of the toner particles to a depth of 0.05d is more than 2 percent of the total number of crystalline resin domains. <3> According to the invention, compared to the case where the number of domains of the release agent located inside the region from the surface of the toner particles to a depth of 0.2d is less than 70 percent of the total number of domains of the release agent, it is possible to provide a toner for electrostatic image development that has low-temperature fixation properties and a low rate of external additive detachment. <4> According to the invention, it is possible to provide a toner for electrostatic image development in which the detachment rate of external additives is lower compared to cases where the domain diameter of the release agent is less than 0.5 μm or greater than 1.5 μm. <5> According to the invention, it is possible to provide a toner for electrostatic image development in which the detachment rate of external additives is lower compared to cases where the aspect ratio of the domains of the crystalline resin is less than 3 or greater than 30. According to the invention related to <6>, it is possible to provide an electrostatic charge image developing toner having a low release rate of external additives as compared with the case where the above ratio (Y / X) is less than 0.2 or more than 30. According to the invention related to <7>, it is possible to provide an electrostatic charge image developing toner having low-temperature fixing properties and a low release rate of external additives as compared with the case where the domain diameter A of the crystalline resin and the domain diameter B of the release agent satisfy the relationship A≧B. According to the invention related to <8>, it is possible to provide an electrostatic charge image developing toner having low-temperature fixing properties and a low release rate of external additives as compared with the case where the above ratio (A / B) is less than 0.2. <9> It has toner particles containing a binder resin containing a crystalline resin and a release agent, and an external additive, and domains of the crystalline resin are present in the toner particles. It is possible to provide an electrostatic charge image developing toner having a low release rate of external additives as compared with the case where the release rate of the external additive with respect to the toner particles is 50% or more.

[0011] According to the inventions related to <10>, <11>, <12>, <13>, or <14>, it has toner particles containing a binder resin containing a crystalline resin and a release agent, and an external additive. When the volume average particle diameter of the toner particles is d, the number of domains of the crystalline resin present in the region from the surface of the toner particles to a depth of 0.2d is less than 30% or more than 90% of the total number of domains of the crystalline resin. An electrostatic charge image developing agent, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method having an electrostatic charge image developing toner having low-temperature fixing properties and a low release rate of external additives is provided.

Brief Description of Drawings

[0012] [Figure 1] It is a schematic configuration diagram showing an example of an image forming apparatus according to the present disclosure. [Figure 2] It is a schematic configuration diagram showing an example of a process cartridge according to the present disclosure. [Figure 3] It is a schematic diagram showing a cross section of toner particles in an electrostatic charge image developing toner according to the present disclosure. [Modes for carrying out the invention]

[0013] An example of one embodiment of the present invention is described in detail below. This description and examples are illustrative of embodiments and do not limit the scope of the embodiments. In this specification, in numerical ranges described in stages, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, within a numerical range, the upper or lower limit of a given numerical range may be replaced with the value shown in the example. In this specification, the amount of each component in a composition means the total amount of any multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that the intended purpose of the process is achieved.

[0014] In this specification, toner for electrostatic image development is also simply referred to as "toner," and electrostatic image developer is also simply referred to as "developer." Furthermore, in this specification, unless otherwise specified, the term "toner relating to this disclosure" refers to both the first and second embodiments described later.

[0015] <First Embodiment of Toner for Electrostatic Image Development> The first embodiment of the electrostatic image developing toner according to the present disclosure (hereinafter also referred to as toner (1) or toner (1)) comprises toner particles containing a binder resin including a crystalline resin and a release agent, and an external additive, wherein when the volume average particle size of the toner particles is d, the number of crystalline resin domains present in the region from the surface of the toner particles to a depth of 0.2d is 30% or more and 90% or less of the total number of crystalline resin domains.

[0016] To achieve low-temperature fixing properties for toner, a method is employed in which crystalline resin is incorporated as a binder resin into the toner particles. However, if a release agent is included in the toner particles along with the crystalline resin, the low-temperature fixing properties may be impaired. This is presumed to be because both the crystalline resin and the release agent have low polarity, causing them to mix within the toner particles and inhibiting the low-temperature fixing effect of the crystalline resin. Therefore, incorporating a large amount of crystalline resin into the toner particles is considered, but in this case, there is a high possibility that the crystalline resin will be exposed on the surface of the toner particles. Since crystalline resin has low resistance and is prone to charge leakage, when the crystalline resin is exposed on the surface of the toner particles, the electrostatic adhesion between the toner particles and the external additive weakens, making it easier for the external additive to detach from the toner particles.

[0017] Therefore, the toner particles of the toner (1) according to this disclosure contain a binder resin containing a crystalline resin and a release agent, and when the volume average particle size of the toner particles is d, the number of crystalline resin domains present in the region from the surface of the toner particles to a depth of 0.2d (hereinafter also referred to as the "outer layer") is between 30% and 90% of the total number of crystalline resin domains. In particular, the presence of 30% to 90% of the total number of crystalline resin domains in the outer layer of such toner particles indicates that while a sufficient amount of crystalline resin domains contributing to low-temperature fixation are present in the outer layer of the toner particles, which is advantageous for the development of low-temperature fixation, the frequency of crystalline resin domains being exposed on the surface of the toner particles is low. Therefore, it is presumed that the toner (1) according to this disclosure, which has such toner particles and an external additive, can keep the detachment rate of the external additive low. Furthermore, the toner (1) according to this disclosure also has excellent low-temperature fixation properties.

[0018] The following describes the domains of the crystalline resin and the release agent in the toner particles. First, referring to the cross-section of the toner particles shown in Figure 3, we will explain the domains of the crystalline resin and the release agent. Figure 3 is a schematic diagram showing a cross-section of toner particles in the toner according to this disclosure. In Figure 3, the symbols TN represent toner particles, Cry represent the crystalline resin domain, Wax represent the release agent domain, Amo represent the binder resin, and Tcg represent the geometric centroid of the toner particle. The region from the solid line showing the surface of the toner particle TN to the dashed line showing a depth of 0.2d from the surface corresponds to the region from the surface to a depth of 0.2d of the toner particle, i.e., the outer layer, when the volume-average particle size of the toner particle is d.

[0019] [Preferred embodiment of toner (1)] In the toner (1) relating to this disclosure, the number of crystalline resin domains present in the outer layer is preferably 30% to 90% of the total number of crystalline resin domains, preferably 50% to 88%, and more preferably 70% to 86%.

[0020] In the toner (1) relating to this disclosure, from the viewpoint of reducing the rate of external additive detachment, the number of crystalline resin domains present in the region from the surface of the toner particle to a depth of 0.05d (hereinafter also referred to as the "surface layer") is preferably 2 percent or less, and more preferably 1 percent or less, relative to the total number of crystalline resin domains. It is particularly preferable that the number of crystalline resin domains present in the surface layer be 0. As described above, from the viewpoint of reducing the rate of external additive detachment, it is preferable for toner particles to have fewer crystalline resin domains present in the surface layer.

[0021] Furthermore, in the toner (1) relating to this disclosure, from the viewpoint of low-temperature fixability and reduction of the detachment rate of external additives, it is preferable that the number of domains of the release agent located inside the region from the surface of the toner particles to a depth of 0.2d (hereinafter also simply referred to as "inside") is 70% or more, more preferably 80% or more, and even more preferably 90% or more, of the total number of domains of the release agent. It is also possible that the number of domains of the release agent located inside is 100% of the total number of domains of the release agent, that is, all of the domains of the release agent are located inside.

[0022] In the toner (1) relating to this disclosure, from the viewpoint of reducing the rate of external additive detachment, the domain diameter of the release agent is preferably 0.5 μm or more and 1.5 μm or less, more preferably 0.6 μm or more and 1.4 μm or less, and even more preferably 0.7 μm or more and 1.3 μm or less. When the domain diameter of the release agent is 0.5 μm or larger, the domains of the crystalline resin are more easily attracted to the domains of the release agent present inside the toner particles, making it difficult for the crystalline resin domains to be exposed on the surface of the toner particles. As a result, the detachment rate of the external additive can be reduced. Furthermore, when the domain diameter of the release agent is 1.5 μm or smaller, low-temperature fixation is also easier to achieve.

[0023] In the toner (1) relating to this disclosure, from the viewpoint of reducing the rate of external additive detachment, the aspect ratio of the domains of the crystalline resin is preferably 3 or more and 30 or less, more preferably 5 or more and 20 or less, and even more preferably . When the aspect ratio of the crystalline resin domains is 30 or less, the crystalline resin domains are less likely to be exposed on the surface of the toner particles, making it easier to reduce the rate of external additive detachment. Furthermore, when the aspect ratio of the crystalline resin domains is 3 or more, it becomes easier to achieve low-temperature fixation.

[0024] In the toner (1) according to the present disclosure, from the viewpoint of reducing the release rate of the external additive, the ratio (Y / X) of the aspect ratio Y of the crystalline resin domain to the aspect ratio X of the mold release agent domain preferably satisfies the relationship of 0.2 ≤ Y / X ≤ 30, more preferably satisfies the relationship of 1.5 ≤ Y / X ≤ 25, and still more preferably satisfies the relationship of 3 ≤ Y / X ≤ 22. When the ratio (Y / X) is 0.2 or more, the variation in the force by which the mold release agent domain inside the toner particles attracts the crystalline resin domain on the surface layer of the toner particles is suppressed, making it difficult for the crystalline resin domain to be exposed on the toner surface and facilitating the reduction of the release rate of the external additive. Also, when the ratio (Y / X) is 30 or less, while suppressing the surface exposure of the crystalline resin domain of the toner particles, it becomes easier to achieve low-temperature fixing properties.

[0025] In the toner (1) according to the present disclosure, from the viewpoint of reducing the release rate of the external additive, it is preferable that the domain diameter A of the crystalline resin and the domain diameter B of the mold release agent satisfy the relationship of A < B. Also, for the same reason, the ratio (A / B) of the domain diameter A of the crystalline resin to the domain diameter B of the mold release agent preferably satisfies the relationship of 0.2 ≤ A / B < 1, more preferably satisfies the relationship of 0.25 ≤ A / B ≤ 0.95, and still more preferably satisfies the relationship of 0.3 ≤ A / B ≤ 0.9. When the domain diameter A of the crystalline resin and the domain diameter B of the mold release agent satisfy the relationship of A < B, it becomes difficult for the crystalline resin domain to be exposed on the surface of the toner particles, and the release rate of the external additive can be reduced.

[0026] Here, the domain diameter of the crystalline resin means the maximum diameter of the crystalline resin domain (that is, the maximum length of a straight line drawn between any two points on the contour line of the crystalline resin domain). Also, the domain diameter of the mold release agent means the maximum diameter of the mold release agent domain (that is, the maximum length of a straight line drawn between any two points on the contour line of the mold release agent domain). The aspect ratio of a crystalline resin domain refers to the ratio of the major axis length to the minor axis length (major axis length / minor axis length). Here, the major axis length of the crystalline resin domain refers to the maximum diameter of the crystalline resin domain, and the minor axis length refers to the maximum length in the direction perpendicular to the maximum diameter. The aspect ratio of a release agent domain refers to the ratio of the major axis length to the minor axis length (major axis length / minor axis length) of the release agent domain. Here, the major axis length of the release agent domain refers to the maximum diameter of the domain, and the minor axis length refers to the maximum length in the direction perpendicular to the maximum diameter. In the region from the surface of the toner particle to a depth of 0.2d or 0.05d, "depth" refers to the distance from the surface of the toner particle in the direction extending from the surface of the toner particle toward its center of gravity.

[0027] The following describes methods for measuring the domain diameter and aspect ratio of domains in crystalline resins and release agents, as well as methods for confirming the location of these domains. These can all be determined by cross-sectional observation of the toner.

[0028] The method for observing the cross-section of toner particles is as follows: Toner particles (or toner particles with external additives attached) are mixed with epoxy resin and embedded, and the epoxy resin is allowed to solidify. The resulting solidified material is cut using an ultramicrotome (Leica UltracutUCT) to prepare thin sections with a thickness of 80 nm to 130 nm. Next, the obtained thin sections are stained with ruthenium tetroxide in a desiccator at 30°C for 3 hours. Then, transmission mode STEM images (acceleration voltage: 30 kV, magnification: 20,000x) of the stained thin sections are obtained using an ultra-high resolution field emission scanning electron microscope (FE-SEM, Hitachi High-Technologies Corporation S-4800). Within the toner particles, the binder resin (crystalline resin and amorphous resin) and release agent are identified based on contrast and shape. In STEM observation images, ruthenium-stained crystalline resins, compared to amorphous resins and release agents, have many double bond regions and are stained by ruthenium tetroxide, thus distinguishing the release agent portion from the other resin portions. More specifically, ruthenium staining stains the release agent lightest, followed by the crystalline resin (e.g., crystalline polyester resin), and then the amorphous resin (e.g., amorphous polyester resin) most intensely. By adjusting the contrast, the release agent appears white, the amorphous resin black, and the crystalline resin light gray. In this way, the domains of the crystalline resin and the domains of the release agent can be distinguished.

[0029] In the STEM observation images, 20 toner particles are extracted using image processing software (e.g., WinROOF2015, Mitani Corporation), and the following measurements are performed on these 20 toner particles. First, identify the locations of all release agent domains and all crystalline resin domains within the toner particles. Then, the number of crystalline resin domains present in the region from the surface of the toner particle to a depth of 0.2d is counted, given that the volume-average particle size of the toner particle is d. In this case, the determination of "present in the region from the surface of the toner particle to a depth of 0.2d" is made based on whether even a part of it is included in the region from the surface of the toner particle to a depth of 0.2d. In other words, crystalline resin domains that are even partially included in the region from the surface of the toner particle to a depth of 0.2d are determined to "present in the region from the surface of the toner particle to a depth of 0.2d". Similarly, the number of crystalline resin domains present in the region from the surface of the toner particle to a depth of 0.05d is counted. Here again, the determination of "present in the region from the surface of the toner particle to a depth of 0.05d" is the same as above; any crystalline resin domain that is even partially contained in the region from the surface of the toner particle to a depth of 0.05d is determined to "present in the region from the surface of the toner particle to a depth of 0.05d". Furthermore, the number of release agent domains located within the region from the surface of the toner particle to a depth of 0.2d is counted. In this case, the determination of "located within the region from the surface of the toner particle to a depth of 0.2d" is made by whether the entire domain is contained within that region. In other words, a release agent domain whose entirety is contained within the region from the surface of the toner particle to a depth of 0.2d is determined to "located within the region from the surface of the toner particle to a depth of 0.2d". The above measurement is performed on 20 toner particles, and the arithmetic mean of the obtained values ​​from these 20 particles is adopted.

[0030] Furthermore, using image processing software (e.g., WinROOF2015, Mitani Corporation) to extract 20 toner particles from the STEM observation images, the domain diameter and aspect ratio of the crystalline resin domain and the release agent domain are measured for each of the 20 toner particles, and the arithmetic mean of the obtained values ​​for each of the 20 particles is calculated. Furthermore, since STEM images contain cross-sections of toner particles of various sizes, we select toner particle cross-sections in which the diameter of the cross-section is 50% or more of the volume-average particle size of the toner particle, and use these as the toner particles to be observed. Here, the diameter of the cross-section of the toner particle refers to the diameter of a circle with the same area as the cross-section of the toner particle (the so-called equivalent circle diameter).

[0031] Furthermore, various average particle sizes, including the volume-average particle size d of the toner particles, and various particle size distribution indices are measured using the Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using the ISOTON-II (manufactured by Beckman Coulter). For measurement, add 0.5 mg to 50 mg of the sample to be measured in 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant. Add this to 100 ml to 150 ml of electrolyte. The electrolyte containing the suspended sample is dispersed in an ultrasonic disperser for 1 minute. The particle size distribution of particles with a diameter of 2 μm to 60 μm is then measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the measured particle size distribution, the cumulative distribution of volume and number is drawn from the smallest diameter side for each divided particle size range (channel). The particle size at which the cumulative total reaches 16% is defined as the volume particle size D16v and the number particle size D16p, the particle size at which the cumulative total reaches 50% is defined as the volume average particle size D50v and the number average particle size D50p, and the particle size at which the cumulative total reaches 84% ​​is defined as the volume particle size D84v and the number particle size D84p. Using these, the volume particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 The GSDp index is (D84p / D16p) 1 / 2 It is calculated as follows.

[0032] The volume-average particle size (d, D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0033] <Second Embodiment of Toner for Electrostatic Image Developing> A second embodiment of the electrostatic image developing toner according to the present disclosure (hereinafter also referred to as toner (2) or toner (2)) comprises toner particles containing a binder resin including a crystalline resin and a release agent, and an external additive, wherein domains of the crystalline resin exist within the toner particles, and the detachment rate of the external additive from the toner particles is less than 50%. As described above, the toner (2) relating to this disclosure has a low rate of external additive removal from toner particles.

[0034] The toner (2) relating to this disclosure preferably has an external additive detachment rate of 40% or less, and more preferably 30% or less. The lower the external additive detachment rate from the toner particles, the better. For example, the lower limit of the external additive detachment rate from the toner particles is 0%, and may also be 10%. Here, the method for measuring the detachment rate of the external additive from the toner particles is the same as the method for measuring the detachment rate of the external additive in the examples.

[0035] In the toner (2) according to this disclosure, when the volume-average particle size of the toner particle is d, it is preferable that the number of crystalline resin domains present in the region from the surface of the toner particle to a depth of 0.2d (i.e., the outer layer) is 30% or more and 90% or less of the total number of crystalline resin domains. In the toner (2) relating to this disclosure, preferred embodiments of the number of crystalline resin domains present in the outer layer of the toner particles, the number of crystalline resin domains present in the surface layer of the toner particles, and the number of release agent domains present inside the toner particles are the same as the preferred embodiments of these items in the toner (1) relating to this disclosure described above. Furthermore, preferred embodiments of the domain diameter of the release agent and the aspect ratio of the domains of the release agent, the domain diameter of the crystalline resin and the aspect ratio of the domains of the crystalline resin, the relationship between the domain diameter of the release agent and the domain diameter of the crystalline resin, and the relationship between the aspect ratio of the domains of the release agent and the aspect ratio of the domains of the crystalline resin in the toner (2) relating to this disclosure are the same as preferred embodiments of these items in the toner (1) relating to this disclosure described above.

[0036] The toner related to this disclosure will be described in detail below. The toner relating to this disclosure comprises toner particles and an external additive.

[0037] (Toner particles) The toner particles contain a binder resin and a release agent. The toner particles may also contain colorants and other additives.

[0038] -Binding resin- The binder resin comprises a crystalline resin, preferably a crystalline resin and an amorphous resin for dispersing the domains of the crystalline resin and the domains of the release agent. The mass ratio of amorphous resin to crystalline resin (crystalline resin / amorphous resin) is preferably 3 / 97 or more and 50 / 50 or less, and more preferably 7 / 93 or more and 30 / 70 or less.

[0039] Here, amorphous resin refers to a material that, in thermal analysis measurements using differential scanning calorimetry (DSC), exhibits only a stepwise endothermic change rather than a clear endothermic peak, is a solid at room temperature, and undergoes thermoplasticization at temperatures above its glass transition temperature. On the other hand, crystalline resins are those that exhibit a clear endothermic peak in differential scanning calorimetry (DSC), rather than a stepwise change in endothermic heat. Specifically, for example, a crystalline resin means that the full width at half maximum (FWHM) of the endothermic peak measured at a heating rate of 10°C / min is within 10°C, while an amorphous resin means a resin whose FWHM exceeds 10°C, or a resin in which no clear endothermic peak is observed.

[0040] Here, amorphous resin refers to a material that, in thermal analysis measurements using differential scanning calorimetry (DSC), exhibits only a stepwise endothermic change rather than a clear endothermic peak, is a solid at room temperature, and undergoes thermoplasticization at temperatures above its glass transition temperature. On the other hand, crystalline resins are those that exhibit a clear endothermic peak in differential scanning calorimetry (DSC), rather than a stepwise change in endothermic heat. Specifically, for example, a crystalline resin means that the full width at half maximum (FWHM) of the endothermic peak measured at a heating rate of 10°C / min is within 10°C, while an amorphous resin means a resin whose FWHM exceeds 10°C, or a resin in which no clear endothermic peak is observed.

[0041] This section will explain amorphous resins. Examples of amorphous resins include known amorphous resins such as amorphous polyester resin, amorphous vinyl resin (e.g., styrene-acrylic resin), epoxy resin, polycarbonate resin, and polyurethane resin. Among these, amorphous polyester resin and amorphous vinyl resin (particularly styrene-acrylic resin) are preferred, and amorphous polyester resin is more preferred. Furthermore, it is also preferable to use amorphous polyester resin and styrene-acrylic resin in combination as the amorphous resin. In addition, it is also preferable to use an amorphous resin having amorphous polyester resin segments and styrene-acrylic resin segments as the amorphous resin. In particular, when an amorphous resin having amorphous polyester resin segments and styrene-acrylic resin segments is used as the amorphous resin, if the aforementioned resins are bonded by ester bonds, it becomes more compatible with ester-based release agents, resulting in superior toner melting properties. Therefore, even when forming images with a large amount of toner at high speed on a recording medium with uneven surfaces, image loss is further suppressed.

[0042] Amorphous polyester resin Examples of amorphous polyester resins include condensation polymers of polycarboxylic acids and polyhydric alcohols. Commercially available amorphous polyester resins may be used, or synthesized ones may be used.

[0043] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., with 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. Polycarboxylic acids may be used in combination with dicarboxylic acids, or with trivalent or higher carboxylic acids that have a cross-linked or branched structure. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). Polycarboxylic acids may be used individually or in combination of two or more.

[0044] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyhydric alcohols, with aromatic diols being more preferred. As for the polyhydric alcohol, a trihydric or higher polyhydric alcohol with a cross-linked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. Polyhydric alcohols may be used individually or in combination of two or more types.

[0045] Amorphous polyester resins can be obtained by known manufacturing methods. Specifically, for example, they can be obtained by a method in which the polymerization temperature is set to 180°C or higher and 230°C or lower, and the reaction system is subjected to reduced pressure as needed, while removing water and alcohol generated during condensation. If the monomers of the raw materials do not dissolve or become miscible at the reaction temperature, a high-boiling point solvent may be added as a solubilizer to dissolve them. In this case, the polycondensation reaction is carried out while distilling off the solubilizer. If there are monomers with poor miscibility in the copolymerization reaction, it is preferable to condense the poorly miscible monomers with the acid or alcohol to be polycondensed with them beforehand, and then polycondense them with the main component.

[0046] In addition to unmodified amorphous polyester resins, modified amorphous polyester resins can also be cited as examples of amorphous polyester resins. Modified amorphous polyester resins are amorphous polyester resins that have bonding groups other than ester bonds, or amorphous polyester resins in which resin components other than polyester are bonded by covalent bonds or ionic bonds. Examples of modified amorphous polyester resins include amorphous polyester resins in which functional groups such as isocyanate groups are introduced at the ends and then reacted with active hydrogen compounds to modify the ends.

[0047] The amorphous polyester resin is preferably present in an amount of 60% to 98% by mass of the total binder resin, more preferably 65% ​​to 95% by mass, and even more preferably 70% to 90% by mass.

[0048] • Styrene acrylic resin Styrene acrylic resin is a copolymer obtained by copolymerizing at least a styrene monomer (a monomer having a styrene skeleton) and a (meth)acrylic monomer (a monomer having (meth)acrylic groups, preferably monomers having (meth)acryloxy groups). Styrene acrylic resin includes, for example, copolymers of styrene monomers and (meth)acrylic acid ester monomers. Furthermore, the acrylic resin portion in styrene-acrylic resin is a substructure formed by polymerizing either an acrylic monomer or a methacrylic monomer, or both. Also, "(meth)acrylic" is an expression that includes both "acrylic" and "methacrylic."

[0049] Examples of styrene monomers include styrene, α-methylstyrene, metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, meta-tert-butoxystyrene, para-tert-butoxystyrene, paravinylbenzoic acid, and paramethyl-α-methylstyrene. Styrene monomers may be used individually or in combination of two or more.

[0050] Examples of (meth)acrylic monomers include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)methacrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. A single (meth)acrylic monomer may be used, or two or more may be used in combination.

[0051] The polymerization ratio of styrene monomers to (meth)acrylic monomers is preferably 70:30 to 95:5 by mass, where styrene monomers : (meth)acrylic monomers are equal.

[0052] Styrene-acrylic resins may have a crosslinked structure. Styrene-acrylic resins having a crosslinked structure can be produced, for example, by copolymerizing a styrene monomer, a (meth)acrylic monomer, and a crosslinkable monomer. The crosslinkable monomer is not particularly limited, but a (meth)acrylate compound with two or more functions is preferred.

[0053] There are no particular restrictions on the method for producing styrene-acrylic resin; for example, solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be used. Known operations (e.g., batch, semi-continuous, continuous, etc.) can be used for the polymerization reaction.

[0054] The proportion of styrene-acrylic resin in the total binder resin is preferably 0% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 2% by mass or more and 10% by mass or less.

[0055] This section explains the properties of amorphous resins. The glass transition temperature (Tg) of amorphous resins is preferably 50°C to 80°C, and more preferably 50°C to 65°C. The glass transition temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, it is determined by the "extracorporeal glass transition onset temperature" described in the method for determining the glass transition temperature in JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics".

[0056] The weight-average molecular weight (Mw) of the amorphous resin is preferably 5,000 to 1,000,000, and more preferably 7,000 to 500,000. The number-average molecular weight (Mn) of the amorphous resin is preferably between 2,000 and 100,000. The molecular weight distribution (Mw / Mn) of the amorphous resin is preferably 1.5 to 100, and more preferably 2 to 60. The weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (GPC). GPC molecular weight measurement is performed using a Tosoh GPC-HLC-8120GPC analyzer, a Tosoh TSKgel SuperHM-M (15cm) column, and THF solvent. The weight-average molecular weight and number-average molecular weight are calculated from these measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0057] This section will explain crystalline resins. Examples of crystalline resins include known crystalline resins such as crystalline polyester resins and crystalline vinyl resins (e.g., polyalkylene resins, long-chain alkyl (meth)acrylate resins, etc.). Among these, crystalline polyester resins are preferred in terms of the mechanical strength of the toner and low-temperature fixability.

[0058] • Crystalline polyester resin Examples of crystalline polyester resins include polycondensates of polycarboxylic acids and polyhydric alcohols. Commercially available crystalline polyester resins may be used, or synthesized resins may be used. For crystalline polyester resins, polycondensates using linear aliphatic polymerizable monomers are preferred over polymerizable monomers having aromatic rings, as they readily form a crystalline structure.

[0059] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., phthalic acid, isophthalic acid, terephthalic acid, dibasic acids such as naphthalene-2,6-dicarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). Polycarboxylic acids may be used in combination with dicarboxylic acids, or with trivalent or higher carboxylic acids that have a crosslinked or branched structure. Examples of trivalent carboxylic acids include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalentricarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). In addition to these dicarboxylic acids, polycarboxylic acids with sulfonic acid groups and dicarboxylic acids with ethylenic double bonds may also be used in combination. Polycarboxylic acids may be used individually or in combination of two or more.

[0060] Examples of polyhydric alcohols include aliphatic diols (for example, linear aliphatic diols with 7 to 20 carbon atoms in the main chain). Examples of aliphatic diols 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 1,14-eicosandecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols. Polyhydric alcohols may be used in combination with diols, including trihydric or higher alcohols that have a cross-linked or branched structure. Examples of trihydric or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. Polyhydric alcohols may be used individually or in combination of two or more types.

[0061] The polyhydric alcohol often contains 80 mol% or more of aliphatic diols, preferably 90 mol% or more.

[0062] Crystalline polyester resins can be obtained, for example, by known manufacturing methods, similar to amorphous polyester resins.

[0063] As the crystalline polyester resin, a polymer of α,ω-linear aliphatic dicarboxylic acid and α,ω-linear aliphatic diol is preferred. Polymers of α,ω-linear aliphatic dicarboxylic acids and α,ω-linear aliphatic diols exhibit high compatibility with amorphous polyester resins. This improves toner melting during fixing and enhances the release agent's leaching, even when forming images with high toner density on uneven recording media at high speeds. As a result, image loss is further suppressed.

[0064] As the α,ω-linear aliphatic dicarboxylic acid, an α,ω-linear aliphatic dicarboxylic acid in which the alkylene group connecting the two carboxyl groups has 3 to 14 carbon atoms is preferred, more preferably the alkylene group has 4 to 12 carbon atoms, and even more preferably the alkylene group has 6 to 10 carbon atoms. Examples of α,ω-linear aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, 1,6-hexanedicarboxylic acid (common name: suberic acid), 1,7-heptanedicarboxylic acid (common name: azelaic acid), 1,8-octanedicarboxylic acid (common name: sebacic acid), 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid. Among these, 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid are preferred. α,ω-linear aliphatic dicarboxylic acids may be used individually or in combination of two or more.

[0065] As the α,ω-linear aliphatic diol, an α,ω-linear aliphatic diol in which the alkylene group connecting the two hydroxyl groups has 3 to 14 carbon atoms is preferred, more preferably the alkylene group has 4 to 12 carbon atoms, and even more preferably the alkylene group has 6 to 10 carbon atoms. Examples of α,ω-linear aliphatic diols 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, 1,12-dodecanediol, 1,14-tetradecanediol, and 1,18-octadecanediol, among which 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred. α,ω-linear aliphatic diols may be used individually or in combination of two or more types.

[0066] As a polymer of α,ω-linear aliphatic dicarboxylic acid and α,ω-linear aliphatic diol, from the viewpoint of suppressing image loss, a polymer of at least one selected from the group consisting of 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid and at least one selected from the group consisting of 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol is preferred, and among these, a polymer of 1,10-decanedicarboxylic acid and 1,6-hexanediol is more preferred.

[0067] The crystalline polyester resin is preferably present in an amount of 1% to 20% by mass of the total binder resin, more preferably 2% to 15% by mass, and even more preferably 3% to 10% by mass.

[0068] This section explains the properties of crystalline resins. The melting temperature of the crystalline resin is preferably 50°C to 100°C, more preferably 55°C to 90°C, and even more preferably 60°C to 85°C. The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in JIS K7121-1987 "Method for determining the transition temperature of plastics".

[0069] The weight-average molecular weight (Mw) of the crystalline resin is preferably between 6,000 and 35,000.

[0070] The binder resin content is preferably 40% to 95% by mass, more preferably 50% to 90% by mass, and even more preferably 60% to 85% by mass, relative to the total toner particles.

[0071] -Release agent- Examples of release agents include hydrocarbon waxes such as paraffin wax; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral / petroleum-based waxes such as montan wax; and ester waxes such as fatty acid esters and montanic acid esters. However, release agents are not limited to these.

[0072] The melting temperature of the release agent is preferably 50°C to 110°C, and more preferably 60°C to 100°C. The melting temperature of the release agent is determined from the DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in JIS K7121:1987 "Method for determining the transition temperature of plastics".

[0073] As a release agent, ester-based waxes are preferred, for example. Ester-based waxes readily form spherical domains of the release agent, resulting in release agent domains with a small aspect ratio. Paraffin wax and Fischer-Tropsch wax may be used as release agents. These waxes promote crystal growth and yield release agent domains with larger aspect ratios compared to ester-based waxes.

[0074] The release agent content is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, relative to the total toner particles.

[0075] -Coloring agent- Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzidine yellow, surene yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, balkan orange, Watch Young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, risole red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, Pigments such as ultramarine blue, chalcioyl blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate; dyes such as acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, and thiazole; are examples. The coloring agent may be used alone or in combination of two or more types.

[0076] The coloring agent may be a surface-treated coloring agent as needed, and may be used in combination with a dispersant. Furthermore, multiple types of coloring agents may be used in combination.

[0077] The colorant content is preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less, relative to the total toner particles.

[0078] -Other additives- Other known additives include, for example, magnetic materials, charge control agents, and inorganic powders. These additives are included in the toner particles as internal additives.

[0079] -Characteristics of toner particles, etc.- The toner particles may be single-layer toner particles, or they may be toner particles with a so-called core-shell structure, consisting of a core (core particle) and a coating layer (shell layer) that covers the core. Here, the core-shell structure of the toner particles may consist of, for example, a core portion comprising a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer comprising a binder resin.

[0080] The volume-average particle size d (also called D50v) of the toner particles is preferably 2 μm or more and 15 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0081] The average circularity of the toner particles is preferably 0.94 to 1.00, and more preferably 0.95 to 0.98.

[0082] The average circularity of toner particles is calculated by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle projection image)]. Specifically, it is a value measured by the following method: First, the toner particles to be measured are collected by suction, a flattened flow is formed, and a still image of the particles is captured by instantaneous strobe flashing. This particle image is then analyzed using a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation). The number of samples used to determine the average circularity is 3500. If the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0083] (External additive) Examples of external additives include inorganic particles. Examples of such inorganic particles include SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2)n, Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, and the like.

[0084] The surface of the inorganic particles used as an external additive should preferably be hydrophobic. Hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic agent. The hydrophobic agent is not particularly limited, but examples include silane-based coupling agents, silicone oil, titanate-based coupling agents, and aluminum-based coupling agents. These may be used individually or in combination of two or more. The amount of hydrophobic treatment agent is typically, for example, 1 to 10 parts by mass per 100 parts by mass of inorganic particles.

[0085] Examples of external additives include resin particles (such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), and cleaning activators (for example, metal salts of higher fatty acids represented by zinc stearate, and fluorine-based high molecular weight particles).

[0086] The amount of external additive is preferably 0.01% to 5% by mass, and more preferably 0.01% to 2.0% by mass, relative to the total mass of toner particles.

[0087] (Toner manufacturing method) Next, the method for manufacturing the toner related to this disclosure will be described. The toner relating to this disclosure is obtained by adding an external additive to toner particles after manufacturing the toner particles.

[0088] Toner particles may be manufactured by either a dry process (e.g., kneading and grinding method) or a wet process (e.g., agglomeration, suspension polymerization, dissolution and suspension method). There are no particular restrictions on the manufacturing method of toner particles, and any well-known method may be used. Among these methods, obtaining toner particles by aggregation and coalescence is preferable because it allows for easier control of the arrangement of domains in the crystalline resin and the arrangement of domain diameters in the release agent.

[0089] Specifically, for example, when manufacturing toner particles by an aggregation and coalescence method, The process involves preparing a resin particle dispersion in which resin particles are dispersed, and a mold release agent particle dispersion in which mold release agent particles are dispersed (particle dispersion preparation process), The process involves a step of forming first aggregated particles by agglomerating resin particles and a release agent particle dispersion in a mixed dispersion of resin particles and a release agent particle dispersion (or, if necessary, in a mixed dispersion after mixing in a colorant dispersion), and After obtaining an aggregated particle dispersion in which the first aggregated particles are dispersed, the process of mixing the aggregated particle dispersion with a resin particle dispersion and agglomerating the first aggregated particles so that resin particles adhere to their surface is called the second aggregated particle formation step (second aggregated particle formation step). After obtaining an aggregate particle dispersion in which the second aggregate particles are dispersed, the aggregate particle dispersion is mixed with the resin particle dispersion to aggregate the second aggregate particles so that the resin particles adhere to the surface of the second aggregate particles, thereby forming third aggregate particles (third aggregate particle formation step). The toner particles are manufactured by heating a dispersion of aggregated particles containing third aggregated particles to fuse and combine the third aggregated particles (fusion and combination step).

[0090] In the above process, a crystalline resin particle dispersion and an amorphous resin particle dispersion are prepared in the particle dispersion preparation step. In the first aggregated particle formation step, it is preferable to use a dispersion of crystalline resin particles and a dispersion of amorphous resin particles. In the second aggregated particle formation step, it is preferable to use an amorphous resin particle dispersion. In the third aggregated particle formation step, it is preferable to use a dispersion of crystalline resin particles and a dispersion of amorphous resin particles.

[0091] In the above process, by using a release agent particle dispersion only in the first aggregated particle formation step, it is possible to form a form in which a large amount of the release agent exists in the first aggregated particles, which correspond to the inside of the toner particles. Subsequently, in the second aggregated particle formation step, the domains of the release agent are grown, and then the third aggregated particle formation step is performed. In the third aggregated particle formation step, by using a larger amount of crystalline resin particle dispersion than used in the first aggregated particle formation step, it is possible to form a form in which a large amount of crystalline resin domains exists in the coating layer formed in the third aggregated particle formation step, which corresponds to the outer layer of the toner particles. In the third aggregated particle formation step, a coating layer containing crystalline resin domains is formed on the outside of the second aggregated particles, which contain domains of the release agent. As previously described, the release agent and the crystalline resin are compatible and attract each other, so if domains of the release agent exist in the second aggregated particles, the domains of the crystalline resin are attracted to the domains of the release agent in the coating layer. As a result, the crystalline resin domains, although present in the coating layer, can suppress their exposure to the surface of the toner particles.

[0092] In the above process, the domain diameter of the release agent can be adjusted by controlling the heating conditions of the aggregated particles (specifically, the heating temperature and heating time) in the second aggregated particle formation step. For example, heating at a high temperature for a long time tends to increase the domain diameter of the release agent. On the other hand, heating at a low temperature for a short time tends to decrease the domain diameter of the release agent. Furthermore, by controlling the cooling conditions (specifically, the cooling rate) during the cooling of high-temperature particles after the fusion and coalescence process (also called the cooling process), the aspect ratio of the crystalline resin domains in the toner particles can be adjusted. A slower cooling rate promotes crystallization of the crystalline resin, which tends to increase the aspect ratio of the crystalline resin domains. Conversely, a faster cooling rate tends to decrease the aspect ratio of the crystalline resin domains.

[0093] The details of each step are explained below. The following explanation describes a method for obtaining toner particles containing a colorant and a mold release agent, but the colorant is used only as needed. Of course, other additives besides colorants may also be used.

[0094] -Resin particle dispersion preparation process- First, along with each resin particle dispersion (amorphous resin particle dispersion and crystalline resin particle dispersion) in which each resin particle that will serve as the binder is dispersed, a colorant particle dispersion in which colorant particles are dispersed and a release agent particle dispersion in which release agent particles are dispersed are prepared.

[0095] Here, the resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium with a surfactant.

[0096] Examples of dispersion media used in resin particle dispersions include aqueous media. Examples of aqueous media include water such as distilled water and deionized water, and alcohols. These may be used individually or in combination of two or more.

[0097] Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycol, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly noteworthy. Nonionic surfactants may be used in combination with anionic or cationic surfactants. Surfactants may be used individually or in combination of two or more types.

[0098] In resin particle dispersions, common dispersion methods for dispersing resin particles in a dispersion medium include, for example, rotary shear homogenizers, ball mills with media, sand mills, and dyno mills. Depending on the type of resin particles, the resin particles may also be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method. Phase inversion emulsification is a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase) to neutralize it, and then an aqueous medium (W phase) is added. This causes a conversion of the resin from W / O to O / W (so-called phase inversion), resulting in a discontinuous phase, and the resin is dispersed in the aqueous medium in particulate form.

[0099] The volume-average particle size of the resin particles dispersed in the resin particle dispersion is preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and even more preferably 0.1 μm or more and 0.6 μm or less. The volume-average particle size of the resin particles is measured using a laser diffraction particle size distribution analyzer (e.g., LA-700, manufactured by Horiba, Ltd.). The particle size distribution is obtained by subtracting the cumulative distribution from the smallest particle size side for each divided particle size range (channel), and the particle size that accounts for 50% of the total particle size is measured as the volume-average particle size D50v. The volume-average particle size of particles in other dispersions is measured in the same manner.

[0100] The resin particle content in the resin particle dispersion is preferably, for example, 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0101] Furthermore, colorant particle dispersions and release agent particle dispersions are prepared in the same manner as resin particle dispersions. In other words, the volume average particle size, dispersion medium, dispersion method, and particle content of the resin particle dispersions are the same for colorant particles dispersed in colorant particle dispersions and release agent particles dispersed in release agent particle dispersions.

[0102] -First agglomerated particle formation process- Next, the resin particle dispersion (preferably a crystalline resin particle dispersion and an amorphous resin particle dispersion), the mold release agent particle dispersion, and the colorant particle dispersion are mixed. Then, in the mixed dispersion, the resin particles, release agent particles, and colorant particles are heteroaggregated to form first aggregated particles containing the resin particles, release agent particles, and colorant particles, which have a diameter close to the diameter of the target toner particles.

[0103] Specifically, for example, after adding a coagulant to a mixed dispersion, the pH of the mixed dispersion is adjusted to be acidic (for example, pH 2 to 5), a dispersion stabilizer is added as needed, and then the mixture is heated to a temperature of the glass transition temperature of the resin particles (specifically, for example, above -30°C to -10°C), causing the particles dispersed in the mixed dispersion to aggregate and form first aggregated particles. In the first agglomerated particle formation step, for example, the mixed dispersion may be stirred in a rotary shear homogenizer, the above-mentioned flocculant may be added at room temperature (e.g., 25°C), the pH of the mixed dispersion may be adjusted to acidic (e.g., pH 2 to 5), a dispersion stabilizer may be added as needed, and then the above-mentioned heating may be performed.

[0104] Examples of flocculants include surfactants with opposite polarity to the surfactant used as a dispersant added to a mixed dispersion, inorganic metal salts, and metal complexes with a valency of 2 or higher. In particular, when a metal complex is used as a flocculant, the amount of surfactant used is reduced and the electrostatic properties are improved. Additives that form complexes or similar bonds with the metal ions of the flocculant may be used as needed. Chelating agents are preferably used as such additives.

[0105] Examples of inorganic metal salts used as flocculants include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. As a chelating agent, a water-soluble chelating agent may be used. Examples of chelating agents include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, as well as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). The amount of chelating agent to be added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of amorphous resin particles, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass.

[0106] -Second agglomerated particle formation process- Next, after obtaining a dispersion of aggregated particles in which the first aggregated particles are dispersed, the dispersion of aggregated particles is mixed with a dispersion of resin particles (preferably a dispersion of crystalline resin particles). Alternatively, the dispersion of aggregated particles may be mixed with a mixture of the dispersion of resin particles and a dispersion of mold release agent resin particles.

[0107] Then, in a dispersion containing the first aggregated particles and resin particles, the resin particles are aggregated onto the surface of the first aggregated particles. Specifically, for example, in the first aggregated particle formation step, when the first aggregated particles reach the desired particle size, a resin particle dispersion is added to the first aggregated particle dispersion, and this dispersion is heated to a temperature below the glass transition temperature of the resin particles. If necessary, this aggregation operation is repeated one or more times to form second aggregated particles. In this case, extending the heating time can promote the growth of the release agent domains in the second aggregated particles.

[0108] -Third agglomerated particle formation process- After obtaining a dispersion of aggregated particles in which the second aggregated particles are dispersed, the dispersion of aggregated particles is mixed with the dispersion of resin particles.

[0109] Then, in a dispersion containing the second aggregated particles and resin particles, the resin particles are aggregated onto the surface of the second aggregated particles. Specifically, for example, in the third aggregated particle formation step, when the second aggregated particles reach the desired particle size, a resin particle dispersion is added to the second aggregated particle dispersion, and this dispersion is heated to a temperature below the glass transition temperature of the resin particles. Then, the pH of the dispersion is adjusted to stop the aggregation process.

[0110] -Fusion / unification process, cooling process- Next, the dispersion of third aggregated particles, in which the third aggregated particles are dispersed, is heated to, for example, a temperature above the glass transition temperature of the resin particles (for example, a temperature 10°C to 30°C higher than the glass transition temperature of the resin particles) to fuse and combine the aggregated particles and form toner particles. Next, the toner particles formed by heating (i.e., toner particles in a high-temperature state) are cooled. Here, when cooling the toner particles formed by heating, the aspect ratio of the domains of the crystalline resin is controlled by controlling the cooling conditions (specifically, the cooling rate) as described above.

[0111] After the fusion and combination process is complete, the toner particles formed in the solution are subjected to known washing, solid-liquid separation, and drying processes to obtain dried toner particles. The washing process should be thoroughly performed using ion-exchanged water for displacement washing, considering the electrostatic charge. The solid-liquid separation process is not particularly restricted, but suction filtration, pressure filtration, etc., are preferable for productivity. The drying process is also not particularly restricted, but freeze-drying, air-flow drying, fluidized bed drying, vibratory fluidized bed drying, etc., are preferable for productivity.

[0112] The toner according to this disclosure is manufactured, for example, by adding an external additive to the obtained dried toner particles and mixing them. Mixing can be performed using, for example, a V-blender, a Henschel mixer, a Redigge mixer, etc. Furthermore, if necessary, coarse particles of the toner may be removed using a vibrating screen separator, a wind screen separator, etc.

[0113] <Electrostatic Image Developer> The electrostatic image developer relating to this disclosure comprises at least the toner relating to this disclosure. The electrostatic image developer relating to this disclosure may be a one-component developer containing only the toner relating to this disclosure, or it may be a two-component developer in which the toner and a carrier are mixed.

[0114] There are no particular restrictions on the carriers, and known carriers can be used. Examples of carriers include coated carriers in which a coating resin is applied to the surface of a core material made of magnetic powder; magnetic powder dispersed carriers in which magnetic powder is dispersed and blended in a matrix resin; and resin-impregnated carriers in which resin is impregnated into porous magnetic powder. Furthermore, magnetic powder dispersed carriers and resin-impregnated carriers may be carriers in which the constituent particles of the carrier are used as a core material and coated with a coating resin.

[0115] Examples of magnetic powders include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0116] Examples of coating resins and matrix resins include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resin or modified thereof containing organosiloxane bonds, fluororesin, polyester, polycarbonate, phenolic resin, epoxy resin, and the like. Furthermore, the coating resin and matrix resin may contain conductive particles or other additives. Examples of conductive particles include metals such as gold, silver, and copper, as well as carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0117] To coat the surface of the core material with a coating resin, one method is to coat it with a coating layer-forming solution in which the coating resin and, if necessary, various additives are dissolved in a suitable solvent. The solvent is not particularly limited and should be selected considering the coating resin used, its suitability for coating, etc. Specific resin coating methods include the immersion method, in which the core material is immersed in a coating layer forming solution; the spray method, in which the coating layer forming solution is sprayed onto the surface of the core material; the fluidized bed method, in which the coating layer forming solution is sprayed onto the core material while it is suspended by fluidized air; and the kneader coater method, in which the carrier core material and the coating layer forming solution are mixed in a kneader coater and the solvent is removed.

[0118] In a two-component developer, the mixing ratio (mass ratio) of toner and carrier is preferably toner:carrier = 1:100 to 30:100, and more preferably 3:100 to 20:100.

[0119] <Image forming device / image forming method> This document describes the image forming apparatus / image forming method related to this disclosure. The image forming apparatus according to this disclosure comprises an image holder, a charging means for charging the surface of the image holder, an electrostatic image forming means for forming an electrostatic image on the charged surface of the image holder, a developing means for containing an electrostatic image developer and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, a transfer means for transferring the toner image formed on the surface of the image holder to the surface of a recording medium, and a fixing means for fixing the toner image transferred to the surface of the recording medium. The electrostatic image developer according to this disclosure is applied as the electrostatic image developer.

[0120] The image forming apparatus according to this disclosure implements an image forming method (image forming method according to this disclosure) comprising: a charging step of charging the surface of an image holder; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image holder; a developing step of developing the electrostatic image formed on the surface of the image holder as a toner image using an electrostatic image developer according to this disclosure; a transfer step of transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0121] The image forming apparatus according to this disclosure includes well-known image forming apparatuses such as: a direct transfer apparatus that directly transfers a toner image formed on the surface of an image holder to a recording medium; an intermediate transfer apparatus that first transfers a toner image formed on the surface of an intermediate transfer body to the surface of an intermediate transfer body, and secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; an apparatus equipped with cleaning means for cleaning the surface of the image holder before charging after the transfer of the toner image; and an apparatus equipped with static elimination means for irradiating the surface of the image holder with static elimination light before charging after the transfer of the toner image. In the case of an intermediate transfer method apparatus, the transfer means may include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer means for primaryly transferring the toner image formed on the surface of the image holder to the surface of the intermediate transfer body; and a secondary transfer means for secondary transferring the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0122] In the image forming apparatus according to this disclosure, for example, the part including the developing means may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with a developing means containing the electrostatic image developer according to this disclosure is preferably used.

[0123] The following is an example of an image forming apparatus related to this disclosure, but is not limited to this example. The main parts shown in the figure will be explained, and other parts will be omitted from the explanation.

[0124] Figure 1 is a schematic diagram showing the image forming apparatus according to this disclosure. The image forming apparatus shown in Figure 1 is equipped with first to fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K (image forming means) that output images of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side at predetermined distances from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may also be process cartridges that can be attached to and detached from the image forming apparatus.

[0125] In the drawings of each unit 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 is extended through each unit as an intermediate transfer body. The intermediate transfer belt 20 is wound around drive rolls 22 and support rolls 24 that are spaced apart from each other from left to right in the drawing and are in contact with the inner surface of the intermediate transfer belt 20, and is configured to travel in the direction from the first unit 10Y to the fourth unit 10K. The support rolls 24 are subjected to a force that moves away from the drive rolls 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around both. In addition, an intermediate transfer body cleaning device 30 is provided on the side of the image holder of the intermediate transfer belt 20, facing the drive rolls 22. Furthermore, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K for each unit 10Y, 10M, 10C, and 10K is supplied with toner containing four colors of toner: yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K.

[0126] Since the first to fourth units 10Y, 10M, 10C, and 10K have equivalent configurations, the first unit 10Y, which forms the yellow image and is located on the upstream side in the direction of travel of the intermediate transfer belt, will be described as a representative example. The descriptions of the second to fourth units 10M, 10C, and 10K will be omitted by assigning reference numerals to parts equivalent to the first unit 10Y, with magenta (M), cyan (C), and black (K) instead of yellow (Y).

[0127] The first unit 10Y has a photoreceptor 1Y that acts as an image holder. Around the photoreceptor 1Y are, in order, a charging roll (an example of a charging means) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, an exposure device (an example of a charge image forming means) 3 that exposes the charged surface with a laser beam 3Y based on a color-separated image signal to form a charge image, a developing device (an example of a developing means) 4Y that supplies charged toner to the charge image to develop the charge image, a primary transfer roll 5Y (an example of a primary transfer means) that transfers the developed toner image onto an intermediate transfer belt 20, and a photoreceptor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoreceptor 1Y after primary transfer. The primary transfer roll 5Y is positioned inside the intermediate transfer belt 20, facing the photoreceptor 1Y. Furthermore, each of the primary transfer rolls 5Y, 5M, 5C, and 5K is connected to a bias power supply (not shown) that applies a primary transfer bias. Each bias power supply varies the transfer bias applied to each primary transfer roll through control by a control unit (not shown).

[0128] The following describes the process of forming the yellow image in the first unit 10Y. First, prior to operation, the surface of the photoreceptor 1Y is charged to a potential of -600V to -800V by the charging roll 2Y. The photoreceptor 1Y is conductive (e.g., volume resistivity at 20°C: 1 × 10⁻⁶). -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate (less than Ωcm). This photosensitive layer normally has high resistance (resistance of general resin), but when irradiated with a laser beam 3Y, the resistivity of the irradiated area changes. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 according to image data for yellow sent from a control unit (not shown). The laser beam 3Y irradiates the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic image of the yellow image pattern on the surface of the photoreceptor 1Y.

[0129] A static charge image is an image formed on the surface of a photoreceptor 1Y due to charging. It is a so-called negative latent image formed when the resistivity of the irradiated portion of the photoreceptor layer decreases due to the laser beam 3Y, causing the charged material on the surface of the photoreceptor 1Y to flow, while the charge remains in the portion not irradiated by the laser beam 3Y. The electrostatic charge image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y moves. At this development position, the electrostatic charge image on the photoreceptor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0130] The developing device 4Y contains, for example, an electrostatic image developer including at least yellow toner and a carrier. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y and is held on the developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the static charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image on the surface of the photoreceptor 1Y, and the latent image is developed by the yellow toner. The photoreceptor 1Y, on which the yellow toner image has been formed, continues to move at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0131] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y acts on the toner image, transferring the toner image on the photoreceptor 1Y onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity opposite to the toner's polarity (-) (+), and in the first unit 10Y, for example, it is controlled to +10 μA by a control unit (not shown). Meanwhile, any toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0132] Furthermore, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K of the second unit from 10M onward is also controlled in accordance with the first unit. Thus, the intermediate transfer belt 20, on which the yellow toner image has been transferred in the first unit 10Y, is sequentially transported through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed and transferred in multiple layers.

[0133] The intermediate transfer belt 20, on which four-color toner images have been multiple-transferred through the first to fourth units, proceeds to a secondary transfer section composed of the intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer means) 26 positioned on the image-holding surface side of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is fed via a supply mechanism into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 at a predetermined timing, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has the same polarity (-) as the toner's polarity (-), and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0134] After this, the recording paper P is fed to the contact area (nip area) of a pair of fixing rolls in a fixing device (an example of fixing means) 28, where the toner image is fixed onto the recording paper P, and a fixed image is formed.

[0135] Examples of recording paper P used to transfer toner images include plain paper used in electrophotographic photocopiers and printers. Other recording media besides recording paper P include OHP sheets. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper, which is plain paper coated with resin or the like, or art paper for printing are preferably used.

[0136] Once the color image has been fixed onto the recording paper P, it is discharged towards the output section, and the series of color image formation operations is completed.

[0137] <Processor Cartridges / Toner Cartridges> This disclosure describes the process cartridge related to this disclosure. The process cartridge according to this disclosure contains an electrostatic image developer according to this disclosure and includes a developing means for developing an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer, and is a process cartridge that can be attached to and detached from an image forming apparatus.

[0138] The process cartridge relating to this disclosure is not limited to the above configuration, and may also include a developing device and, as necessary, at least one selected from, for example, an image holder, a charging means, an electrostatic image forming means, and a transfer means.

[0139] The following is an example of a process cartridge related to this disclosure, but is not limited to this example. The main parts shown in the figure will be explained, and other parts will not be described.

[0140] Figure 2 is a schematic diagram showing the process cartridge related to this disclosure. The process cartridge 200 shown in Figure 2 is constructed by integrally holding a photoreceptor 107 (an example of an image holder), a charging roll 108 (an example of a charging means) provided around the photoreceptor 107, a developing device 111 (an example of a developing means), and a photoreceptor cleaning device 113 (an example of a cleaning means) within a housing 117 equipped with a mounting rail 116 and an opening 118 for exposure, and is then formed into a cartridge. In Figure 2, 109 represents an exposure apparatus (an example of electrostatic image formation means), 112 represents a transfer apparatus (an example of a transfer means), 115 represents a fixing apparatus (an example of a fixing means), and 300 represents recording paper (an example of a recording medium).

[0141] Next, we will describe the toner cartridge related to this disclosure. The toner cartridge relating to this disclosure is a toner cartridge that contains the toner relating to this disclosure and is attached to and detached from an image forming apparatus. The toner cartridge contains replenishment toner for supply to a developing means provided within the image forming apparatus.

[0142] The image forming apparatus shown in Figure 1 is an image forming apparatus with removable toner cartridges 8Y, 8M, 8C, and 8K. The developing units 4Y, 4M, 4C, and 4K are connected to toner cartridges corresponding to each developing unit (color) by toner supply pipes (not shown). When the toner contained in a toner cartridge becomes low, the toner cartridge is replaced. [Examples]

[0143] The embodiment will be described in more detail below with reference to examples and comparative examples, but this embodiment is not limited to these examples. Unless otherwise specified, "parts" and "%" refer to mass.

[0144] [Preparation of resin particle dispersion] <Preparation of amorphous polyester resin particle dispersion (A1)> (Preparation of amorphous polyester resin (A)) Terephthalic acid: 70 parts Fumaric acid: 30 parts • Ethylene glycol: 41 parts • 1,5-Pentanediol: 48 parts The above materials were placed in a 5-liter flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and rectification column. The temperature was raised to 220°C over 1 hour under a nitrogen gas stream, and 1 part titanium tetraethoxide was added for every 100 parts of the above materials. The temperature was raised to 240°C over 0.5 hours while distilling off the generated water, and the dehydration condensation reaction was continued at this temperature for 1 hour, after which the reactants were cooled. In this way, an amorphous polyester resin (A) with a weight-average molecular weight of 96,000 and a glass transition temperature of 61°C was synthesized.

[0145] (Preparation of amorphous polyester resin particle dispersion (A1)) In a container equipped with temperature control and nitrogen purging means, 40 parts of ethyl acetate and 25 parts of 2-butanol were added to form a mixed solvent. Then, 100 parts of amorphous polyester resin (A) were gradually added and dissolved. A 10% aqueous ammonia solution (equivalent to 3 times the molar ratio of the acid value of the resin) was added and stirred for 30 minutes. Next, the container was purged with dry nitrogen, and the temperature was maintained at 40°C. While stirring the mixture, 400 parts of deionized water were added dropwise at a rate of 2 parts / minute to emulsify it. After the dropwise addition was complete, the emulsion was returned to 25°C to obtain a resin particle dispersion in which resin particles with a volume average particle size of 190 nm were dispersed. Deionized water was added to the resin particle dispersion to adjust the solid content to 20% to obtain amorphous polyester resin particle dispersion (A1).

[0146] <Preparation of crystalline polyester resin particle dispersion (B1)> (Preparation of crystalline polyester resin (B)) • 1,10-Decanedicarboxylic acid: 265 parts • 1,6-Hexanediol: 168 parts • Dibutyltin oxide (catalyst): 0.3 parts After placing the above components into a heated and dried three-necked flask, the air inside the container was removed by reducing the pressure to create an inert atmosphere with nitrogen gas, and the mixture was stirred and refluxed at 180°C for 5 hours using mechanical stirring. Subsequently, the temperature was gradually increased to 230°C under reduced pressure and stirred for 2 hours until a viscous state was reached, at which point the reaction was stopped by air cooling. Molecular weight measurement (polystyrene equivalent) showed that the weight-average molecular weight (Mw) of the obtained "crystalline polyester resin (B)" was 12700, and the melting temperature was 73°C.

[0147] (Preparation of crystalline polyester resin particle dispersion (B1)) 90 parts by mass of crystalline polyester resin (B), 1.8 parts by mass of ionic surfactant Neogen RK (Daiichi Kogyo Seiyaku), and 210 parts by mass of ion-exchanged water were heated to 120°C and thoroughly dispersed in an IKA Ultra-Turrax T50. The dispersion was then carried out for 1 hour in a pressure-discharge type Gorin homogenizer to obtain a crystalline polyester resin particle dispersion (B1) with a volume-average particle size of 190 nm and a solid content of 20 parts by mass.

[0148] [Preparation of mold release agent particle dispersion] <Preparation of mold release agent particle dispersion (W1)> 70 parts of ester wax (NOF Corporation, WEP-5, melting point 85°C), 1 part by mass of anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK), and 200 parts by mass of ion-exchanged water were mixed and dispersed for 10 minutes using a homogenizer (IKA Corporation, Ultra-Turrax T50). Ion-exchanged water was added to the dispersion so that the solid content was 20% by mass to obtain a colorant particle dispersion (W1). The volume-average particle size of the colorant particles in the colorant particle dispersion was 195 nm.

[0149] <Preparation of mold release agent particle dispersion (W2)> Release agent particle dispersion (W2) was prepared in the same manner as the release agent particle dispersion (W1), except that the ester-based wax (NOF Corporation, WEP-5, melting temperature 85°C) was replaced with paraffin wax (Nippon Seiro Co., Ltd., HNP-0190, melting temperature 89°C).

[0150] <Preparation of mold release agent particle dispersion (W3)> Release agent particle dispersion (W3) was prepared in the same manner as the release agent particle dispersion (W1), except that the ester-based wax (manufactured by NOF Corporation, WEP-5, melting point 85°C) was replaced with Fischer-Tropsch wax (manufactured by Nippon Seiro Co., Ltd., FT-105).

[0151] [Preparation of a dispersion of coloring agent particles] <Preparation of colorant particle dispersion (C1)> • Carbon black (Cabot Regal 330): 50 units • Ionic surfactant Neogen RK (Daiichi Kogyo Seiyaku): 5 parts • Ion-exchanged water: 193 parts The above components were mixed and treated with an ultimateizer (manufactured by Sugino Machine Co., Ltd.) at 240 MPa for 10 minutes to prepare a colorant particle dispersion (C1) with a solid content of 20%.

[0152] <Example 1> - Toner particle production - • Ion-exchanged water: 200 bottles • Amorphous polyester resin particle dispersion (A1): 180 parts • Crystalline polyester resin particle dispersion (B1): 20 parts • Coloring agent particle dispersion (C1): 25 parts • Release agent particle dispersion (W1): 35 parts Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd.: Neogen RK, 20%): 2.5 parts The above components were placed in a 3-liter reaction vessel equipped with a thermometer, pH meter, and stirrer, and the mixture was stirred at 150 rpm for 20 minutes. Subsequently, a 0.3N nitric acid aqueous solution was added to adjust the pH of the system to 3.5.

[0153] Next, while dispersing in a homogenizer (IKA Japan: Ultra-Turrax T50), an aqueous PAC solution was added, prepared by dissolving 1.2 parts of PAC (Oji Paper Co., Ltd.: 30% powder) in 10 parts of deionized water. Then, while stirring, the temperature was raised to 50°C, and the particle size was measured using a Coulter Multisizer II (aperture diameter: 50 μm, Coulter) until the volume-average particle size reached 5.2 μm (first aggregated particle formation step). Next, 20 parts of amorphous polyester resin dispersion (A1) were added and held for 20 minutes. Then, the pH was adjusted to 6.5 using 1N sodium hydroxide, and subsequently, the mixture was heated to 75°C and held for 60 minutes (second aggregated particle formation step). Subsequently, the mixture was cooled to 50°C, a 0.3N nitric acid aqueous solution was added to adjust the pH of the system to 4.5, and a mixture of 25 parts amorphous polyester resin dispersion (A1) and 65 parts crystalline polyester resin dispersion (B1) was added, followed by holding for 30 minutes. Next, 15 parts of a 10% aqueous solution of metal nitrilotriacetate (Kirest 70: manufactured by Kirest Co., Ltd.) were added, and the pH was further adjusted to 9.5 using 1N sodium hydroxide (third aggregated particle formation step). Subsequently, the particles were heated to 80°C and held for 120 minutes to fuse and coalesce, and then cooled to 30°C at a rate of 2°C / minute (fusion and coalescing step, and cooling step). The obtained toner particles were redispersed in deionized water, repeatedly filtered, and washed until the electrical conductivity of the filtrate was 20 uS / cm or less. Then, the toner particles were obtained by vacuum drying in a 40°C oven for 5 hours.

[0154] -Toner production- For every 100 parts of the obtained toner particles (1), 1.5 parts of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., RY50) and 1.0 part of hydrophobic titanium oxide (manufactured by Nippon Aerosil Co., Ltd., T805) were mixed using a sample mill at 10,000 rpm (revolutions per minute) for 30 seconds. Subsequently, the mixture was sieved using a vibrating sieve with a mesh size of 45 μm to prepare toner (1). The volume-average particle size of the toner particles (1) in the obtained toner (1) was 6.4 μm.

[0155] <Examples 2-27, Comparative Examples 1 and 2> Toner particles (2) to (27) were obtained in the same manner as in Example 1, except that the type and amount (amount charged) of the release agent particle dispersion used in the first aggregated particle formation step, the heating temperature and holding time after pH adjustment in the second aggregated particle formation step, and the cooling rate of the particles that have been fused and combined by heating at 80°C and holding for 120 minutes in the cooling step after the fusion and combination step were appropriately changed according to Table 1. Then, using the obtained toner particles, toners (2) to (27) were obtained in the same manner as in Example 1.

[0156] <Characteristics> For each example of toner, the following characteristics were measured for the toner particles according to the method described above. • The percentage of crystalline resin domains present in the region from the surface of the toner particle to a depth of 0.2d [number of domains] • The percentage of crystalline resin domains present in the region from the surface of the toner particle to a depth of 0.05d [percentage] • The percentage of release agent domains located in the region from the surface of the toner particle to a depth of 0.2d [number of domains] • Domain diameter B of the release agent Domain diameter A of crystalline resin • Aspect ratio X of the domain of the release agent • Aspect ratio Y of the domains in crystalline resin • The ratio (Y / X) of the aspect ratio of the crystalline resin domains to the aspect ratio of the release agent domains X. The ratio of the domain diameter A of the crystalline resin to the domain diameter B of the mold release agent (A / B) The results are shown in Tables 1 and 2.

[0157] <Preparation of electrostatic image developer> The obtained toner was mixed with 8 parts by mass of resin-coated ferrite carrier (average particle size 35 μm) to prepare a two-component developer, thereby obtaining a developer (electrostatic image developer). The resulting developers were each loaded into the developer unit of a DocuPrint C2220 (Fuji Xerox) and seasoned for 24 hours in a low-temperature, low-humidity environment (10°C / 15%RH).

[0158] <Rating> (Low temperature fixation) The developer obtained in each example was loaded into the developer unit of a modified Fuji Xerox Apeosport6-C7771 (with the fuser unit modified to allow for variable fixing temperature), and the fuser roll surface temperature of the fuser unit was changed from 60°C to 200°C in 10°C increments, and the solid portion (toner application amount: 4.5g / m²) was measured at each temperature. 2Images of the solid areas and fine lines were extracted. A fold was made in the center of these solid area fixed images, and the destruction of the fixed image was evaluated visually. The fixing temperature at which a problem level was achieved was defined as the minimum fixing temperature (MFT(°C)), and the images were evaluated according to the following evaluation criteria. A smaller MFT(°C) value indicates better low-temperature fixing performance. The results are shown in Tables 1 and 2.

[0159] -Evaluation Criteria for Low-Temperature Fixation- G1: MFT ≤ 110℃ G2: 110℃ <MFT≦125℃ G3: 125℃ <MFT≦140℃ G4: 140℃ <MFT

[0160] (Transferable) Under conditions of 28°C and 85% humidity, a modified DocuCentreColor400 (Fuji Xerox) was used to print image samples with rectangular patches drawn to achieve an image density of 1% onto embossed paper (Lezac 66, 203gsm, manufactured by Tokushu Tokai Paper Co., Ltd.). The images were then evaluated for image quality (checking for color loss). The transferability grade was determined by visual inspection of the obtained images according to the following criteria. Grades G1 to G3 were considered acceptable for practical use. The results are shown in Tables 1 and 2.

[0161] - Evaluation Criteria for Transcriptional Properties - • G1: No color loss occurs in the recessed areas of the embossed paper. • G2: In the recessed areas of the embossed paper, there are gaps in the image area of ​​10% or less. • G3: In the recessed areas of the embossed paper, there are gaps in the image area of ​​less than 30%. • G4: In the recessed areas of the embossed paper, there are gaps in the image area of ​​30% or more.

[0162] (Withdrawal rate from external additives) In a glass bottle, deionized water and octylphenol ethoxylate (Triton X100 aqueous solution (manufactured by Acros Organics)) are added, and 5g of the toner to be evaluated is added to the mixture. The mixture is stirred 30 times and allowed to stand for at least 1 hour. After that, the mixture is stirred 20 times, and ultrasonic energy is applied for 1 minute using an ultrasonic homogenizer (manufactured by SONICS&MATERIALS Co., Ltd., product name homogenizer, model VCX750, CV33) with the output dial set to 30% under the following conditions. Next, the mixture to which ultrasonic energy has been applied is filtered by suction using filter paper (product name: qualitative filter paper (No. 2, 110mm), manufactured by Advantec Toyo Co., Ltd.), washed twice again with deionized water, and after filtering out the free particles (external additives), the toner is dried. The amount of particles remaining in the toner after particle removal using the above process (hereinafter referred to as the amount of particles after dispersion) and the amount of particles in the toner that has not undergone the above particle removal process (hereinafter referred to as the amount of particles before dispersion) are quantified using X-ray fluorescence. The values ​​of the amount of particles before dispersion and the amount of particles after dispersion are substituted into Equation 1 below, and the calculated value is defined as the particle release rate. Equation 1: Particle (external additive) release rate (mass %) = [(amount of particles before dispersion - amount of particles after dispersion) / amount of particles before dispersion] × 100 The detachment rates of the obtained particles are shown in Tables 1 and 2 as the detachment rates of the external additives.

[0163] [Table 1]

[0164] [Table 2]

[0165] From the above results, it can be seen that this embodiment has low-temperature fixation properties and a low rate of external additive detachment. Furthermore, it was found that this embodiment also exhibits excellent transferability. [Explanation of symbols]

[0166] 1Y, 1M, 1C, 1K Photoreceptor (an example of an image retainer) 2Y, 2M, 2C, 2K Charging Rolls (Example of Charging Method) 3. Exposure apparatus (an example of electrostatic image formation means) 3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing apparatus (an example of a developing method) 5Y, 5M, 5C, 5K Primary Transfer Rolls (Example of Primary Transfer Method) 6Y, 6M, 6C, 6K Photoreceptor Cleaning Device (Example of Cleaning Method) 8Y, 8M, 8C, 8K Toner Cartridges 10Y, 10M, 10C, 10K Image Forming Units 20. Intermediate transfer belt (an example of an intermediate transfer material) 22 Drive Roll 24 Support Rolls 26. Secondary transfer roll (an example of a secondary transfer means) 30 Intermediate Transfer Body Cleaning Apparatus 107 Photoreceptor (an example of an image-retaining element) 108 Charging Roll (Example of Charging Method) 109 Exposure apparatus (an example of a means for forming electrostatic images) 111 Developing apparatus (an example of a developing means) 112 Transfer device (an example of a transfer means) 113 Photoreceptor cleaning device (an example of a cleaning method) 115 Fixing device (an example of a fixing means) 116 Mounting Rail 118 Aperture for exposure 117 cabinets 200 Process Cartridges 300 Recording paper (an example of a recording medium) P Recording paper (an example of a recording medium)

Claims

1. The toner particles contain a binder resin including crystalline resin and amorphous resin, and a release agent, and an external additive. The toner particles have domains of the crystalline resin and domains of the mold release agent dispersed in the amorphous resin, and the mass ratio of the amorphous resin to the crystalline resin (crystalline resin / amorphous resin) is 7 / 93 or more and 30 / 70 or less. When the volume-average particle size of the toner particle is d, the number of domains of the crystalline resin present in the region from the surface of the toner particle to a depth of 0.2d is 70% or more and 90% or less of the total number of domains of the crystalline resin. The number of domains of the crystalline resin present in the region from the surface of the toner particle to a depth of 0.05d is 2 percent or less of the total number of domains of the crystalline resin. The volume-average particle size d of the toner particles is 2 μm or more and 10 μm or less. A toner for developing electrostatic images, wherein the crystalline resin is a crystalline polyester resin and the amorphous resin is an amorphous polyester resin.

2. The toner for developing electrostatic images according to claim 1, wherein the number of domains of the release agent located in the region from the surface of the toner particles to a depth of 0.2d is 70% or more of the total number of domains of the release agent.

3. The toner for developing electrostatic images according to claim 2, wherein the domain diameter of the release agent is 0.5 μm or more and 1.5 μm or less.

4. The electrostatic image developing toner according to any one of claims 1 to 3, wherein the aspect ratio of the domains of the crystalline resin is 3 or more and 30 or less.

5. The electrostatic image developing toner according to any one of claims 1 to 4, wherein the ratio (Y / X) of the aspect ratio Y of the domains of the crystalline resin to the aspect ratio X of the domains of the mold release agent satisfies the relationship 0.2 ≤ Y / X ≤ 30.

6. The electrostatic image developing toner according to any one of claims 1 to 5, wherein the domain diameter A of the crystalline resin and the domain diameter B of the mold release agent satisfy the relationship A < B.

7. The electrostatic image developing toner according to claim 6, wherein the ratio of the domain diameter A of the crystalline resin to the domain diameter B of the mold release agent (A / B) satisfies the relationship 0.2 ≤ A / B < 1.

8. The electrostatic image developing toner according to any one of claims 1 to 7, wherein the detachment rate of the external additive from the toner particles is less than 50%.

9. A electrostatic image developer comprising the electrostatic image developing toner according to any one of claims 1 to 8.

10. A toner for electrostatic image development according to any one of claims 1 to 8 is contained, A toner cartridge that is attached to and detached from an image forming machine.

11. The development means comprises a static charge image developer according to claim 9, and develops a static charge image formed on the surface of an image holder as a toner image using the static charge image developer, A process cartridge that is attached to and detached from an image forming apparatus.

12. Image holder and, A charging means for charging the surface of the image holder, A means for forming an electrostatic image on the surface of the charged image holder, A developing means comprising: containing the electrostatic image developer described in claim 9; and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer; A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, Fixing means for fixing the toner image transferred to the surface of the recording medium, An image forming apparatus equipped with the following features.

13. A charging step in which the surface of the image holder is charged, A step of forming an electrostatic image on the surface of the charged image holder, A developing step of developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer described in claim 9, A transfer step of transferring the toner image formed on the surface of the image holder to the surface of the recording medium, A fixing step for fixing the toner image transferred to the surface of the recording medium, An image forming method having the following characteristics.

Images