Electrostatic image developing toner, electrostatic image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method

Abstract

The present invention relates to a toner for electrostatic image development, an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method. The toner for electrostatic image development has toner particles including an amorphous resin and a crystalline resin, and at least two crystalline resin domains satisfy the following conditions (A), (B1), (C), and (D) when a cross section of the toner particles is observed. Condition (A): an aspect ratio of the crystalline resin domain is 5 to 40. Condition (B1): a long axis length of the crystalline resin domain is 0.5 to 1.5 μm. Condition (C): an angle formed by an extension line of the long axis of the crystalline resin domain and a tangent line (the tangent line is a tangent line at a point where the extension line and a surface of the toner particle meet) is 60 to 90 degrees. Condition (D): an intersection angle of the extension lines of the long axes of the two crystalline resin domains is 45 to 90 degrees.

Description

Technical Field

[0001] This invention relates to toners for electrostatic image development, electrostatic image developers, toner cartridges, processing cartridges, image forming apparatus, and image forming methods. Background Technology

[0002] Electrophotography and other methods for visualizing image information are currently used in various fields. In electrophotography, an electrostatic image, serving as image information, is formed on the surface of an image holder through charging and electrostatic image formation. Then, a toner image is formed on the surface of the image holder using a developer containing a toner. This toner image is transferred to a recording medium and fixed thereon. Through these steps, the image information is visualized as an image.

[0003] For example, Japanese Patent Application Publication No. 2019-40024 discloses "a colorant comprising a plurality of colorant particles, each colorant particle having a colorant core and a shell covering the surface of the colorant core, wherein the colorant core contains a melt blend of an amorphous resin and a crystalline resin, the shell contains a thermosetting resin, the melt blend contains two or more crystalline resin microregions, and among the two or more crystalline resin microregions contained in the colorant particles, the proportion of microregions satisfying the conditions of a short axis diameter of 50 nm or more and 200 nm or less and an aspect ratio of 4.0 or more and 20.0 or less is 80% or more".

[0004] In addition, Japanese Patent Application Publication No. 2017-003990 discloses "a colorant comprising colorant particles containing an amorphous polyester resin, a crystalline polyester resin, and a wax, characterized in that, in the cross-section of the colorant observed using a transmission electron microscope (TEM), there are micro-regions of the wax and crystals of the crystalline polyester resin, wherein in the cross-sectional area of ​​the colorant, the area occupied by the micro-regions of the wax is 0.5% to 8.0% and the area occupied by the crystals of the crystalline polyester resin is 0.5% to 8.0%, the number average diameter (Dw) of the micro-regions of the wax is 60 nm to 240 nm and the aspect ratio of the crystals of the crystalline polyester resin is 5.0 to 25.0 and the number average diameter (Dc) of the long axis length of the crystals of the crystalline polyester resin is 0.8 times to 2.0 times the number average diameter (Dw) of the micro-regions of the wax". Summary of the Invention

[0005] The technical problem that the invention aims to solve

[0006] The technical problem to be solved by the present invention is to provide a toner for electrostatic image development that, compared with the case where a toner for electrostatic image development containing toner particles comprising amorphous resin and crystalline resin has toner particles in which, when the cross-section of the toner particle is observed, all the crystalline resin micro-regions do not satisfy any one of the following conditions (A), (B1), (C), and (D), respectively; or the case where, when the cross-section of the toner particle is observed, all the crystalline resin micro-regions do not satisfy any one of the following conditions (A), (B2), (C), and (D), respectively, suppresses the degree of uneven gloss in the image when forming an image with a large amount of toner loading.

[0007] Means for solving technical problems

[0008] According to a first aspect of the present invention, a toner for electrostatic image development is provided, which has toner particles comprising an amorphous resin and a crystalline resin, wherein, when the cross-section of the toner particles is observed, at least two of the crystalline resin microregions satisfy the following conditions (A), (B1), (C), and (D) (hereinafter also referred to as first toner particles).

[0009] Condition (A): The aspect ratio of the above-mentioned crystalline resin microregions is 5 or more and 40 or less.

[0010] Condition (B1): The major axis length of the above-mentioned crystalline resin microregions is 0.5 μm or more and 1.5 μm or less.

[0011] Condition (C): The angle formed by the extension of the long axis of the above-mentioned crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the above-mentioned colorant particles) is more than 60 degrees and less than 90 degrees.

[0012] Condition (D): The angle between the extensions of the major axes of the two crystalline resin microregions mentioned above is more than 45 degrees and less than 90 degrees.

[0013] According to a second aspect of the present invention, a toner for electrostatic image development is provided, which has toner particles comprising an amorphous resin and a crystalline resin, wherein, when the cross-section of the toner particles is observed, at least two of the crystalline resin microregions satisfy the following conditions (A), (B2), (C), and (D) (hereinafter also referred to as second toner particles).

[0014] Condition (A): The aspect ratio of the above-mentioned crystalline resin microregions is 5 or more and 40 or less.

[0015] Condition (B2): In at least one of the two crystalline resin microregions described above, the ratio of the long axis length to the maximum diameter of the colorant particles is more than 10% and less than 30%.

[0016] Condition (C): The angle formed by the extension of the long axis of the above-mentioned crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the above-mentioned colorant particles) is more than 60 degrees and less than 90 degrees.

[0017] Condition (D): The angle between the extensions of the major axes of the two crystalline resin microregions mentioned above is more than 45 degrees and less than 90 degrees.

[0018] According to a third aspect of the present invention, the toner particles contain a release agent, and when the cross-section of the toner particles is observed, the micro-regions of the release agent exist inside at a depth of 50 nm or more from the surface of the toner particles.

[0019] According to the fourth embodiment of the present invention, the release agent is an ester-based wax.

[0020] According to the fifth aspect of the present invention, the content of the above-mentioned colorant particles is 40% or more relative to all colorant particles.

[0021] According to the sixth aspect of the present invention, the content of the above-mentioned colorant particles is 70% or more relative to all colorant particles.

[0022] According to a seventh aspect of the present invention, an electrostatic image developer is provided, which comprises the above-mentioned electrostatic image developing toner.

[0023] According to the eighth aspect of the present invention, a toner cartridge that is loaded and unloaded in an image forming apparatus is provided, which stores the aforementioned toner for electrostatic image development.

[0024] According to a ninth aspect of the present invention, a processing cartridge that is loaded and unloaded in an image forming apparatus is provided, which includes a developing mechanism that stores the electrostatic image developer and uses the electrostatic image developer to develop an electrostatic image formed on the surface of an image holder into a toner image.

[0025] According to a tenth aspect of the present invention, an image forming apparatus is provided, comprising: an image holder; a charging mechanism for charging the surface of the image holder; an electrostatic image forming mechanism for forming an electrostatic image on the charged surface of the image holder; a developing mechanism for storing the electrostatic image developer and developing the electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer; a transfer mechanism for transferring the toner image formed on the surface of the image holder to a surface of a recording medium; and a fixing mechanism for fixing the toner image transferred to the surface of the recording medium.

[0026] According to the eleventh aspect of the present invention, an image forming method is provided, comprising the following steps: a charging step, charging the surface of an image holder; an electrostatic image forming step, forming an electrostatic image on the charged surface of the image holder; a developing step, developing the electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer; a transfer step, transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step, fixing the toner image transferred to the surface of the recording medium.

[0027] The effects of the invention

[0028] According to the first embodiment described above, an electrostatic image developing tone agent is provided. Compared with the case where an electrostatic image developing tone agent containing toner particles comprising amorphous resin and crystalline resin has only toner particles in which at least two crystalline resin micro-regions do not satisfy the above conditions (A), (B1), (C), and (D) when the cross-section of the toner particles is observed, the electrostatic image developing tone agent of this embodiment can suppress the degree of uneven gloss of the image generated when forming an image with a large amount of toner loading.

[0029] According to the second embodiment described above, an electrostatic image developing tone agent is provided. Compared with the case where an electrostatic image developing tone agent containing toner particles comprising amorphous resin and crystalline resin has only toner particles in which at least two crystalline resin micro-regions do not satisfy the above conditions (A), (B2), (C), and (D) when the cross-section of the toner particles is observed, the electrostatic image developing tone agent of this embodiment can suppress the degree of uneven gloss of the image generated when forming an image with a large amount of toner loading.

[0030] According to the third scheme described above, an electrostatic image developing toner is provided. Compared with the case where the micro-region of the release agent exists at a depth of less than 50 nm from the surface of the toner particles, the electrostatic image developing toner of this scheme can suppress the degree of uneven gloss of the image when forming an image with a large amount of toner loading.

[0031] According to the fourth embodiment above, a colorant for electrostatic image development is provided. Compared with the case where the release agent is a polyethylene wax or an alkane wax, the colorant for electrostatic image development of this embodiment can suppress the degree of uneven gloss of the image when forming an image with a large amount of colorant loading.

[0032] According to the fifth or sixth embodiment described above, a toner for electrostatic image development is provided. Compared with cases where the content of the first toner particles and the second toner particles is less than 40% or less than 70%, the toner for electrostatic image development of this embodiment can suppress the degree of uneven gloss in the image when forming an image with a large amount of toner loading.

[0033] According to the above-mentioned schemes 7, 8, 9, 10 or 11, an electrostatic image developer, toner cartridge, processing cartridge, image forming apparatus or image forming method is provided. Compared with the case of using the electrostatic image developer toner described below, the electrostatic image developer, toner cartridge, processing cartridge, image forming apparatus or image forming method of the above-mentioned scheme can suppress the degree of uneven gloss of the image when forming an image with a large amount of toner loading. The electrostatic image developer toner used is an electrostatic image developer toner having toner particles containing amorphous resin and crystalline resin, which has toner particles in which at least two crystalline resin micro-regions do not meet the above conditions (A), (B1), (C) and (D) when the cross-section of the toner particles is observed; or an electrostatic image developer toner having toner particles in which at least two crystalline resin micro-regions do not meet the above conditions (A), (B2), (C) and (D) when the cross-section of the toner particles is observed. Attached Figure Description

[0034] Figure 1 This is a schematic configuration diagram illustrating an example of the image forming apparatus of this embodiment.

[0035] Figure 2 This is a schematic configuration diagram illustrating an example of the processing box of this embodiment.

[0036] Figure 3 This is a schematic diagram showing the cross-section of the toner particles in the electrostatic image developing toner of this embodiment. Detailed Implementation

[0037] The following is a detailed description of an embodiment of the present invention.

[0038] It should be noted that, within the numerical range recorded in stages, the upper or lower limit value recorded in a certain numerical range can be replaced with the upper or lower limit value of the numerical range of other stages recorded.

[0039] In addition, within the numerical range, the upper or lower limit value recorded in a certain numerical range can be replaced with the value shown in the embodiment.

[0040] Regarding the amount of each component in the composition, if there are two or more substances that conform to each component in the composition, unless otherwise stated, it refers to the total amount of the two or more substances present in the composition.

[0041] The term "step" includes not only independent steps, but also steps that achieve their intended purpose, even if they cannot be clearly distinguished from other steps.

[0042] <Toning agents for electrostatic image development>

[0043] (First Implementation)

[0044] The electrostatic image developing toner (hereinafter referred to as "toner") of the first embodiment has the following first toner particles:

[0045] The first colorant particle contains amorphous resin and crystalline resin. When the cross-section of the colorant particle is observed, at least two crystalline resin microregions satisfy the following conditions (A), (B1), (C), and (D).

[0046] Condition (A): The aspect ratio of the crystalline resin microregions is 5 or higher and 40 or lower.

[0047] Condition (B1): The major axis length of the crystalline resin microregion is 0.5 μm or more and 1.5 μm or less.

[0048] Condition (C): The angle formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the colorant particles) is more than 60 degrees and less than 90 degrees.

[0049] Condition (D): The angle between the extensions of the major axes of the two crystalline resin microregions is more than 45 degrees and less than 90 degrees.

[0050] The toner in the first embodiment, through the above-described configuration, can suppress the degree of uneven gloss in the image when forming an image with a large amount of toner loading. The reason for this is presumably as follows.

[0051] To impart a three-dimensional texture to an image, a stereoscopic image, sometimes called thick ink printing, is created. Thick ink printing primarily employs multiple printing passes, but the more passes, the more time-consuming it becomes, and the more prone it is to printing errors. Therefore, there is a search for methods to reduce the number of print passes by increasing the amount of toner loaded. One well-known technique involves shaping the crystalline resin micro-regions within the toner particles into elliptical shapes, ensuring compatibility between the amorphous resin and the crystalline resin during toner image fixing, thus facilitating the melting of the toner particles (e.g., Patent Document 1).

[0052] However, in this technology, the crystalline resin micro-regions within the toner particles are all oriented in the same direction. Therefore, the presence of crystalline resin on the surface of the toner particles may be uneven. Consequently, when the toner loading is increased (e.g., increasing the toner loading to 10.0 g / m³), the... 2 When heat is applied evenly throughout the toner particles (as described above), uneven melting of the toner particles may occur during toner image fixing. This can result in uneven gloss in the image.

[0053] In contrast, for the first toner particles that meet the above conditions, heat is easily transferred almost uniformly within the toner particles, and uneven melting of the toner particles is less likely to occur during toner image fixing.

[0054] Here, the first colorant particle satisfying the above conditions means that two crystalline resin microregions with a large aspect ratio, elliptical or needle-shaped, and long major axis length extend from the surface side of the colorant particle inward and are arranged in an intersecting manner (see reference). Figure 3 ).

[0055] Furthermore, when fixing a toner image with first toner particles that satisfy the above conditions, after heat is applied to the first toner particles, heat is easily and rapidly transferred from the surface of the first toner particles to the interior through the melting of the elliptical or needle-shaped crystalline resin. Thus, heat is transferred almost uniformly throughout the toner particles, facilitating melting in a nearly uniform state throughout the toner particles.

[0056] Therefore, even if the toner loading is increased (e.g., even if the toner loading is increased to 10.0 g / m³), 2 (Above), uneven melting of toner particles is less likely to occur during toner image fixing.

[0057] It can be inferred from the above that the toner in the first embodiment can suppress the degree of uneven gloss in the image when forming an image with a large amount of toner loading.

[0058] (Second Implementation)

[0059] The electrostatic image developing toner (hereinafter referred to as "toner") in the second embodiment is an electrostatic image developing toner having the following second toner particles:

[0060] The second colorant particles contain amorphous resin and crystalline resin. When the cross-section of the colorant particles is observed, at least two crystalline resin microregions satisfy the following conditions (A), (B2), (C), and (D).

[0061] Condition (A): The aspect ratio of the crystalline resin microregions is 5 or higher and 40 or lower.

[0062] Condition (B2): In at least one of the two crystalline resin microregions described above, the ratio of the long axis length to the maximum diameter of the colorant particles is more than 10% and less than 30%.

[0063] Condition (C): The angle formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the colorant particles) is more than 60 degrees and less than 90 degrees.

[0064] Condition (D): The angle between the extensions of the major axes of the two crystalline resin microregions is more than 45 degrees and less than 90 degrees.

[0065] The toner in the second embodiment, through the above-described configuration, can suppress the degree of uneven gloss in the image when forming an image with a large amount of toner loading. The reason for this is presumably as follows.

[0066] Regarding the second toner particles that meet the above conditions, heat is easily transferred almost uniformly within the toner particles, and uneven melting of the toner particles is less likely to occur during toner image fixing.

[0067] Here, the second colorant particle satisfying the above conditions, similar to the first colorant particle in the first embodiment, refers to two crystalline resin microregions with a large aspect ratio, elliptical or needle-shaped, and long major axis, extending from the surface side of the colorant particle inward and arranged in an intersecting manner (see reference). Figure 3 ).

[0068] Therefore, the second colorant particles are also similar to the first colorant particles in the first embodiment, even if the colorant loading is increased (e.g., even if the colorant loading is increased to 10.0 g / m³). 2 (Above), uneven melting of toner particles is less likely to occur during toner image fixing.

[0069] Furthermore, when fixing a toner image with second toner particles that meet the above conditions, after heat is applied to the second toner particles, heat is easily and rapidly transferred from the surface of the second toner particles to the interior through the melting of the elliptical or needle-shaped crystalline resin. Thus, heat is uniformly transferred throughout the toner particles, facilitating melting in a near-uniform state across the entire toner particle structure.

[0070] It can be inferred from the above that the toner in the second embodiment can suppress the degree of uneven gloss in the image when forming an image with a large amount of toner loading.

[0071] Here, Figure 3 The symbols shown represent:

[0072] TN: Toning agent particles

[0073] Amo: Amorphous resin

[0074] Cry: Crystalline resin

[0075] L Cry Length of the major axis of the crystalline resin microregion

[0076] L T The maximum diameter of the colorant particles

[0077] θ A The angle formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent being the tangent at the point where the extension intersects the surface of the colorant particle)

[0078] θ B The angle between the extensions of the long axes of the two crystalline resin microregions.

[0079] The following describes in detail a colorant that conforms to both the first embodiment and the second embodiment (hereinafter also referred to as "the colorant of this embodiment"). However, any example of the colorant of the present invention can be a colorant that conforms to either the first or second embodiment. It should be noted that the first colorant particles and the second colorant particles are also referred to as colorant particles in the description.

[0080] The colorant in this embodiment has colorant particles. The colorant may contain additives.

[0081] (Coloring agent granules)

[0082] The colorant particles contain both amorphous and crystalline resins as binding agents. It should be noted that the colorant particles may also contain colorants, release agents, and other additives.

[0083] -Morphology of crystalline resin microdomains in colorant particles-

[0084] When observing the cross-section of the colorant particles, at least two crystalline resin microregions (preferably at least three crystalline resin microregions) must satisfy conditions (A), (B1), (B2), (C), and (D). Specifically, at least two crystalline resin microregions must satisfy at least one of conditions (B1) and (B2).

[0085] Here, from the perspective of suppressing uneven gloss in the image, the toner particles satisfying each condition are preferably 40% or more, more preferably 70% or more, further preferably 80% or more, and particularly preferably 90% or more relative to all toner particles. Ideally, the proportion of toner particles satisfying the above conditions is 100%.

[0086] The more toner particles that meet the above conditions, the easier it is for the toner particles to melt in a nearly uniform state, and the easier it is to suppress uneven gloss in the image.

[0087] It should be noted that, regarding the preferred range of toner particles satisfying the conditions described below, from the perspective of suppressing uneven gloss in the image, similarly to the above, it is preferably 40% or more, more preferably 70% or more, further preferably 80% or more, and particularly preferably 90% or more, relative to all toner particles. Ideally, the proportion of toner particles satisfying the above conditions is 100%.

[0088] The conditions are explained below.

[0089] ·Condition(A)

[0090] The aspect ratio of the crystalline resin microregions is between 5 and 40.

[0091] From the perspective of suppressing uneven gloss in the image, the aspect ratio of the crystalline resin micro-region is preferably 10 or more and 40 or less.

[0092] Here, the aspect ratio of the crystalline resin microregion refers to the ratio of the major axis length to the minor axis length (major axis length / minor axis length) in the crystalline resin microregion.

[0093] The major axis length of a crystalline resin microregion refers to the maximum length of the crystalline resin microregion.

[0094] The short axis length of a crystalline resin microregion refers to the maximum length among the lengths in the direction orthogonal to the extension of the long axis length of the crystalline resin microregion.

[0095] • Condition (B1)

[0096] The major axis length of the crystalline resin microregion (refer to) Figure 3 L in Cry The value is between 0.5μm and 1.5μm.

[0097] From the perspective of suppressing uneven gloss in the image, the long axis length of the crystalline resin micro-region is preferably 0.8 μm or more and 1.5 μm or less.

[0098] • Condition (B2)

[0099] In at least one of the two aforementioned crystalline resin microregions, the major axis length (refer to...) Figure 3 L in Cry ) relative to the maximum diameter of the above-mentioned colorant particles (refer to Figure 3 L in T The proportion is between 10% and 30%.

[0100] From the perspective of suppressing uneven gloss in the image, the ratio of the long axis length of the crystalline resin micro-region to the maximum diameter of the toner particles is preferably 13% to 30%, more preferably 17% to 30%.

[0101] The maximum diameter of a colorant particle refers to the maximum length of a straight line drawn from any two points on the outline of the cross-section of the colorant particle (the so-called major diameter).

[0102] • Condition (C)

[0103] The angle formed by the extension of the long axis of the crystalline resin microregion and the tangent (the tangent being the tangent at the point where the extension intersects the surface of the colorant particle (i.e., the outer edge of the colorant particle) (refer to...) Figure 3 θ A (60 degrees or higher and 90 degrees or lower)

[0104] From the perspective of suppressing uneven gloss in the image, the angle formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the toner particle) is preferably 75 degrees or more and 90 degrees or less.

[0105] ·Condition(D)

[0106] The angle between the extensions of the major axes of the two crystalline resin microregions (refer to...) Figure 3 θ B (45 degrees or higher and 90 degrees or lower)

[0107] From the perspective of suppressing uneven gloss in the image, the intersection angle of the extended lines of the long axes of the two crystalline resin micro-regions (refer to...) Figure 3 θ B The preferred temperature is between 60 degrees and 90 degrees.

[0108] Here, in the colorant particles, even if there are more than three crystalline resin microregions that satisfy conditions (A), (B1), and (C), or conditions (A), (B2), and (C), it is acceptable as long as any two of the crystalline resin microregions satisfy condition (D).

[0109] • Method for observing the cross-section of colorant particles

[0110] The following is a method for observing the cross-section of colorant particles to determine whether they meet conditions (A), (B1), (B2), (C), and (D).

[0111] Toner particles (or toner particles with adhering additives) were mixed and embedded in epoxy resin, which was then cured. The cured material was cut using an ultramicrotome (Leica Ultracut UCT) to prepare thin sections with a thickness of 80 nm to 130 nm. The resulting thin sections were then stained with ruthenium tetroxide in a desiccator at 30 °C for 3 hours. Subsequently, STEM images of the stained thin sections were obtained using a high-resolution field emission scanning electron microscope (FE-SEM, Hitachi High-Tech S-4800) in transmission mode (accelerating voltage: 30 kV, magnification: 20,000x).

[0112] In the colorant particles, the crystalline polyester resin and the release agent are distinguished by contrast and shape. In the SEM image, among the ruthenium-stained crystalline resin, compared with amorphous resin and release agent, the adhesive resin other than the release agent has many double bond sites that are stained by ruthenium tetroxide, thus the release agent part and the resin part other than the release agent can be identified.

[0113] That is, through ruthenium staining, the release agent stains the lightest micro-areas, followed by crystalline resins (such as crystalline polyester resins), and amorphous resins (such as amorphous polyester resins) stain the darkest. After adjusting the contrast, micro-areas that appear white can be identified as release agents, micro-areas that appear black can be identified as amorphous resins, and micro-areas that appear light gray can be identified as crystalline resins.

[0114] Then, image analysis was performed on the micro-regions of the ruthenium-stained crystalline resin to determine whether the toning agent particles met conditions (A), (B1), (B2), (C), and (D).

[0115] In addition, after determining the proportion of toner particles that meet the above conditions, 100 toner particles were observed, and the proportion of toner particles that meet the above conditions was calculated.

[0116] It should be noted that when the SEM image contains cross-sections of toner particles of various sizes, the toner particle cross-sections with a diameter greater than 85% of the volume average particle diameter should be selected as the toner particles to be observed. Here, the diameter of the toner particle cross-section refers to the maximum length of the straight line drawn from any two points on the outline of the toner particle cross-section (the so-called major axis).

[0117] -Adhesive resin-

[0118] The adhesive resins used are amorphous resins and crystalline resins.

[0119] The mass ratio of amorphous resin to crystalline resin (crystalline resin / amorphous resin) is preferably 3 / 97 or more and 50 / 50 or less, more preferably 7 / 93 or more and 30 / 70 or less.

[0120] Here, amorphous resin refers to the following resins: resins that do not have a clear endothermic peak in thermal analysis using differential scanning calorimetry (DSC), only exhibit stepwise endothermic changes, are solid at room temperature, and undergo thermoplasticization at temperatures above the glass transition temperature.

[0121] On the other hand, crystalline resin refers to resin that does not exhibit a step-like change in endothermic heat during differential scanning calorimetry (DSC) and has a distinct endothermic peak.

[0122] Specifically, for example, crystalline resin refers to resin whose half-peak width of the endothermic peak is less than 10°C when measured at a heating rate of 10°C / min, while amorphous resin refers to resin whose half-peak width is greater than 10°C, or resin for which no clear endothermic peak has been identified.

[0123] Amorphous resins will be described.

[0124] Examples of amorphous resins include amorphous polyester resins, amorphous vinyl resins (such as styrene-acrylic resins), epoxy resins, polycarbonate resins, and polyurethane resins. Among these, amorphous polyester resins and amorphous vinyl resins (especially styrene-acrylic resins) are preferred, and amorphous polyester resins are more preferred.

[0125] It should be noted that combining amorphous polyester resin with styrene-acrylic resin as an amorphous resin is also a preferred method.

[0126] Examples of amorphous polyester resins include condensation polymers of polycarboxylic acids and polyols. It should be noted that both commercially available and synthetic amorphous polyester resins can be used.

[0127] Examples of polycarboxylic acids include, for example, aliphatic dicarboxylic acids (such as oxalic acid, malonic acid, maleic acid, fumaric acid, citracic acid, itaconic acid, pentenic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (such as cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or their lower (e.g., alkyl esters with 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids.

[0128] In polycarboxylic acids, dicarboxylic acids may be used in combination with tricarboxylic acids or more carboxylic acids that have a cross-linked or branched structure. Examples of tricarboxylic acids or more carboxylic acids include trimellitic acid, benzopyrene, their anhydrides, or their lower (e.g., 1 to 5 carbon atoms) alkyl esters.

[0129] Polycarboxylic acids can be used alone or in combination of two or more.

[0130] Examples of polyols include aliphatic diols (such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (such as cyclohexanediol, cyclohexanediol, hydrogenated bisphenol A, etc.), and aromatic diols (such as ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyols, and aromatic diols are more preferred.

[0131] As a polyol, the diol can also be used in combination with a tri- or higher polyol that has a cross-linked or branched structure. Examples of tri- or higher polyols include glycerol, trimethylolpropane, and pentaerythritol.

[0132] Polyols can be used alone or in combination of two or more.

[0133] Amorphous polyester resins are obtained by known manufacturing methods. Specifically, for example, they are obtained by means of: setting the polymerization temperature to 180°C or higher and 230°C or lower, and, as needed, reducing the pressure within the reaction system while removing water or alcohol generated during condensation.

[0134] It should be noted that if the raw material monomers are insoluble or incompatible at the reaction temperature, a high-boiling-point solvent can be added as a dissolving agent to dissolve them. In this case, the polycondensation reaction is carried out while the dissolving agent is removed by distillation. In the presence of monomers with poor compatibility, the monomers with poor compatibility can be pre-condensed with the acid or alcohol to which they are to be polycondensed, and then polycondensed together with the main component.

[0135] Here, in addition to the unmodified amorphous polyester resins mentioned above, modified amorphous polyester resins can also be cited as examples of amorphous polyester resins. Modified amorphous polyester resins refer to amorphous polyester resins containing linking groups other than ester bonds, or amorphous polyester resins with resin components different from those of amorphous polyester resins bonded by covalent or ionic bonds. Examples of modified amorphous polyester resins include resins whose ends are modified by reacting an amorphous polyester resin with functional groups such as isocyanate groups that react with acid groups or hydroxyl groups with an active hydrogen compound.

[0136] Styrene-acrylic resins are copolymers formed by copolymerization of styrene monomers (monomers having a styrene backbone) and (meth)acrylic monomers (monomers having (meth)acryloyl groups, preferably monomers having (meth)acryloyloxy groups). Styrene-acrylic resins include, for example, copolymers of styrene monomers and (meth)acrylate monomers.

[0137] It should be noted that the acrylic resin portion in styrene-acrylic resin can be either an acrylic monomer or a methacrylic monomer, or a partial structure formed by the polymerization of these two. Furthermore, the term "(meth)acrylic acid" includes both "acrylic acid" and "methacrylic acid".

[0138] As styrene monomers, examples include styrene, alkyl-substituted styrene (e.g., α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, etc.), halogen-substituted styrene (e.g., 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, etc.), and vinylnaphthalene. Styrene monomers can be used alone or in combination of two or more.

[0139] Among these, styrene is preferred as a styrene monomer in terms of reactivity, ease of reaction control, and availability.

[0140] As monomers of (meth)acrylic acid, examples specifically include (meth)acrylic acid and (meth)acrylates. Examples of (meth)acrylates include alkyl (meth)acrylates (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isoamyl (meth)acrylate, amyl (meth)acrylate, neopentyl (meth)acrylate, etc. (Methacrylic acid) monomers include isohexyl methacrylate, isoheptyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, etc.; aryl methacrylic acid monomers (e.g., phenyl methacrylate, biphenyl methacrylate, diphenyl ethyl methacrylate, tert-butyl phenyl methacrylate, terphenyl methacrylate, etc.); dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methoxyethyl methacrylate, 2-hydroxyethyl methacrylate, β-carboxyethyl methacrylate, and methacrylamide, etc. A single methacrylic acid monomer can be used, or two or more monomers can be used in combination.

[0141] It should be noted that, from the perspective of fixing properties, among the (meth)acrylic monomers, (meth)acrylates having alkyl groups having 2 to 14 carbon atoms (preferably 2 to 10 carbon atoms, more preferably 3 to 8 carbon atoms) are preferred.

[0142] Preferred of the mixture is n-butyl methacrylate, and particularly preferred is n-butyl acrylate.

[0143] There are no particular restrictions on the copolymerization ratio of styrene monomers to (meth)acrylic monomers (by mass, styrene monomer / (meth)acrylic monomer), but it is preferably 85 / 15 to 70 / 30.

[0144] Styrene-acrylic resins can also have a cross-linked structure. Examples of preferred cross-linked styrene-acrylic resins include resins copolymerized from styrene monomers, (meth)acrylic monomers, and cross-linking monomers.

[0145] Examples of crosslinking monomers include crosslinking agents with two or more functions.

[0146] Examples of difunctional crosslinking agents include divinylbenzene, divinylnaphthalene, di(meth)acrylate compounds (e.g., diethylene glycol di(meth)acrylate, methylene bis(meth)acrylamide, decanediol diacrylate, glycidyl (meth)acrylate, etc.), polyester-type di(meth)acrylate, 2-([1'-methylpropyleneamino]carboxyamino)ethyl methacrylate, etc.

[0147] Examples of multifunctional crosslinking agents include tri(meth)acrylate compounds (such as pentaerythritol tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc.), tetra(meth)acrylate compounds (such as pentaerythritol tetra(meth)acrylate, low polyester (meth)acrylate, etc.), 2,2-bis(4-methacryloyloxy, polyethoxyphenyl)propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl chloroxylate, etc.

[0148] Among them, as a crosslinking monomer, from the perspective of suppressing the occurrence of image density reduction, suppressing the occurrence of image density unevenness, and fixing, a (meth)acrylate compound with two or more functions is preferred, a (meth)acrylate compound with two functions is more preferred, a (meth)acrylate compound with two functions having alkylene groups having 6 to 20 carbon atoms is even more preferred, and a (meth)acrylate compound with two functions having straight-chain alkylene groups having 6 to 20 carbon atoms is particularly preferred.

[0149] There are no particular limitations on the copolymerization ratio of crosslinking monomer to all monomers (by mass, crosslinking monomer / all monomers), but it is preferably 2 / 1,000 to 20 / 1,000.

[0150] There are no particular restrictions on the production method of styrene-acrylic resin; various polymerization methods can be used (e.g., solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc.). Furthermore, the polymerization reaction should employ well-known operating procedures (e.g., batch, semi-continuous, continuous, etc.).

[0151] The properties of amorphous resins are explained.

[0152] The glass transition temperature (Tg) of the amorphous resin is preferably 50°C or higher and 80°C or lower, more preferably 50°C or higher and 65°C or lower.

[0153] It should be noted that the glass transition temperature is determined by the DSC curve obtained by differential scanning calorimetry (DSC), or more specifically, by the "extrapolation of the glass transition onset temperature" described in the method for determining the glass transition temperature of plastics in JIS K 7121-1987 "Method for determination of transition temperature of plastics".

[0154] The weight-average molecular weight (Mw) of the amorphous resin is preferably 5,000 to 1,000,000, more preferably 7,000 to 500,000.

[0155] The number average molecular weight (Mn) of the amorphous resin is preferably between 2,000 and 100,000.

[0156] The molecular weight distribution of the amorphous resin, Mw / Mn, is preferably 1.5 to 100, more preferably 2 to 60.

[0157] It should be noted that the weight-average molecular weight and number-average molecular weight were determined by gel permeation chromatography (GPC). For the molecular weight determination using GPC, a Tosoh GPC·HLC-8120 GPC was used as the measuring apparatus, a Tosoh TSKgelSuperHM-M (15 cm) column was used, and THF solvent was employed. The weight-average molecular weight and number-average molecular weight were calculated from these results using a molecular weight calibration curve prepared from monodisperse polystyrene standard samples.

[0158] The crystalline resin is described.

[0159] Examples of crystalline resins include crystalline polyester resins and crystalline vinyl resins (such as polyalkylene resins, long-chain (meth)acrylate resins, etc.). Among these, crystalline polyester resins are preferred from the perspective of the mechanical strength and low-temperature fixing properties of the colorant.

[0160] Examples of crystalline polyester resins include condensation polymers of polycarboxylic acids and polyols. It should be noted that commercially available products or synthetic compounds can be used as crystalline polyester resins.

[0161] Here, in order to facilitate the formation of a crystalline structure in the crystalline polyester resin, the crystalline polyester preferably uses a condensation polymer obtained from a linear aliphatic polymer, compared to a condensation polymer obtained using a polymer with aromatic polymers.

[0162] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (such as oxalic acid, succinic acid, glutaric acid, adipic acid, octanoic 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 (such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, etc.), their anhydrides, or their lower (e.g., alkyl esters with 1 to 5 carbon atoms).

[0163] In polycarboxylic acids, dicarboxylic acids may also be used in combination with tricarboxylic acids or more that have a cross-linked or branched structure. Examples of tricarboxylic acids include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, or their lower (e.g., alkyl esters with 1 to 5 carbon atoms).

[0164] As polycarboxylic acids, these dicarboxylic acids can be used in combination with dicarboxylic acids having sulfonic acid groups or dicarboxylic acids having olefinic double bonds.

[0165] Polycarboxylic acids can be used alone or in combination of two or more.

[0166] Examples of polyols include aliphatic diols (e.g., straight-chain 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-eicosenediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols.

[0167] In polyols, diols can also be used in combination with tri- or higher alcohols that have cross-linked or branched structures. Examples of tri- or higher alcohols include glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0168] Polyols can be used alone or in combination of two or more.

[0169] Here, the content of aliphatic diols in the polyol can be 80 mol% or more, preferably 90 mol% or more.

[0170] Crystalline polyester resins are obtained, for example, by known manufacturing methods, similar to amorphous polyesters.

[0171] The characteristics of crystalline resins are explained.

[0172] 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.

[0173] It should be noted that the melting temperature is determined based on the DSC curve obtained by differential scanning calorimetry (DSC) according to the "melting peak temperature" recorded in the method for determining the melting temperature of plastics in JISK 7121:1987 "Method for determination of the transition temperature of plastics".

[0174] The weight-average molecular weight (Mw) of the crystalline resin is preferably 6,000 or more and 35,000 or less.

[0175] The content of the adhesive resin is preferably 40% to 95% by mass or less, more preferably 50% to 90% by mass or less, and even more preferably 60% to 85% by mass or less, relative to the total amount of colorant particles.

[0176] -Coloring agents-

[0177] Examples of coloring agents include carbon black, chrome yellow, Hansa yellow, benzidine yellow, vat yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, sulfur-resistant orange, Voochug red, permanent red, bright carmine 3B, bright carmine 6B, DuPont oil red, pyrazolone red, litho red, rhodamine B lake, lake red C, pigment red, rose red, aniline blue, cyanine blue, oil-soluble blue, methylene chloride blue, phthalocyanine blue, pigment blue, phthalocyanine green, malachite green oxalate, and various other pigments, or dyes based on acridine, xanthine, azo, benzoquinone, azazine, anthraquinone, thioindigo, dioxazine, thiazine, azomethyl alkali, indigo, phthalocyanine, aniline black, polyacetylenes, triphenylmethane, diphenylmethane, thiazole, etc.

[0178] Colorants can be used alone or in combination of two or more.

[0179] Colorants can be surface-treated as needed, or they can be used in combination with dispersants. Additionally, two or more colorants can be used together.

[0180] The content of the colorant is preferably 1% to 30% by mass or less, more preferably 3% to 15% by mass or less, relative to the total amount of colorant particles.

[0181] -Release agent-

[0182] Examples of release agents include: hydrocarbon waxes; natural waxes such as carnauba wax, rice bran wax, and candelilla wax; synthetic or mineral / petroleum-based waxes such as lignite wax; ester waxes such as fatty acid esters and lignite esters; and so on.

[0183] The melting temperature of the release agent is preferably 50°C to 110°C, more preferably 60°C to 100°C.

[0184] It should be noted that the melting temperature is determined by the "melting peak temperature" described in JISK 7121-1987 "Method for determination of the transformation temperature of plastics" based on the DSC curve obtained by differential scanning calorimetry (DSC).

[0185] In particular, when ester-based waxes are used as release agents, they are preferred from the perspective of suppressing uneven gloss in images.

[0186] Ester waxes are waxes containing ester bonds. As ester waxes, they can be any of monoesters, diesters, triesters, and tetraesters, and can be well-known natural or synthetic ester waxes.

[0187] Examples of ester-based waxes include ester compounds formed between higher fatty acids (fatty acids with 10 or more carbon atoms, etc.) and mono- or poly-aliphatic alcohols (aliphatic alcohols with 8 or more carbon atoms, etc.) with a melting temperature of 60°C to 110°C (preferably 65°C to 100°C, more preferably 70°C to 95°C).

[0188] Examples of ester waxes include ester compounds formed between higher fatty acids (octanoic acid, capric acid, lauric acid, tetradecanoic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, etc.) and alcohols (methanol, ethanol, propanol, isopropanol, butanol, octanol, lauryl alcohol, myristol, cetyl alcohol, stearyl alcohol, oleyl alcohol, etc. monohydric alcohols; glycerol, ethylene glycol, propylene glycol, sorbitol, pentaerythritol, etc. polyhydric alcohols). Specifically, examples include carnauba wax, rice bran wax, candelilla wax, jojoba oil, wood wax, beeswax, insect wax, lanolin, and lignite ester wax.

[0189] In colorant particles where at least two crystalline resin microregions satisfy conditions (A), (B1), (B2), (C), and (D), when observing the cross-section of the colorant particle, the release agent microregion preferably exists within a depth of 50 nm or more from the surface of the colorant particle. That is, when observing the cross-section of the colorant particle, the shortest distance between the release agent microregion present in the colorant particle and the surface (i.e., the outer edge) of the colorant particle is 50 nm or more.

[0190] The release agent's micro-regions existing at a depth of more than 50 nm from the surface of the toner particles mean that these micro-regions are not exposed on the surface of the toner particles. Once these micro-regions are exposed, the additives will preferentially adhere to the exposed areas. Therefore, if the release agent's micro-regions exist at a depth of more than 50 nm from the surface of the toner particles, the additives tend to adhere more uniformly, easily suppressing uneven melting of the toner particles during fixing. This, in turn, easily suppresses uneven gloss in the image.

[0191] The confirmation that the release agent micro-regions exist within a depth of more than 50 nm from the surface of the colorant particles is carried out by the cross-sectional observation method of the colorant particles described above.

[0192] It should be noted that, from the perspective of suppressing uneven gloss in the image, the proportion of toner particles in which at least two crystalline resin micro-regions satisfy the above conditions, and where the release agent micro-regions exist at a depth of 50 nm or more from the surface of the toner particles, is preferably 40% or more, more preferably 70% or more, further preferably 80% or more, and particularly preferably 90% or more, relative to all toner particles. Ideally, the proportion of toner particles satisfying the above conditions is 100%.

[0193] The content of the release agent is preferably 1% to 20% by mass and more preferably 5% to 15% by mass relative to the total amount of colorant particles.

[0194] -Other Additives-

[0195] Other known additives include, for example, magnetic materials, charge control agents, and inorganic powders. These additives are contained in the colorant particles as internal additives.

[0196] -Characteristics of colorant particles, etc.-

[0197] Toner particles can be monolayer toner particles or so-called core / shell toner particles consisting of a core (core particle) and a coating layer (shell) covering the core.

[0198] Here, the core / shell structured colorant particles can, for example, consist of a core and a coating layer, the core being formed by including an adhesive resin and, if necessary, other additives such as colorants and release agents, and the coating layer being formed by including an adhesive resin.

[0199] The volume average particle size (D50v) of the colorant particles is preferably 2 μm or more and 15 μm or less, more preferably 4 μm or more and 8 μm or less.

[0200] It should be noted that the various average particle sizes and particle size distribution parameters of the colorant particles were measured using a Coulter Multisizer II (manufactured by Beckman Coulter) and the electrolyte was measured using ISOTON-II (manufactured by Beckman Coulter).

[0201] During the determination, 0.5 mg to 50 mg of the test sample is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant. This is then added to 100 ml to 150 ml of electrolyte.

[0202] The electrolyte containing the suspended sample was dispersed using an ultrasonic disperser for 1 minute. The particle size distribution of particles ranging from 2 μm to 60 μm was measured using a Coulter Multisizer II with 100 μm pores. It should be noted that 50,000 particles were sampled.

[0203] For the particle size range (interval) divided based on the measured particle size distribution, the cumulative distribution of volume and number is plotted from the small diameter side. The particle size at the cumulative 16% point is defined as the volumetric particle size D16v and the number particle size D16p. The particle size at the cumulative 50% point is defined as the volume average particle size D50v and the cumulative number average particle size D50p. The particle size at the cumulative 84% point is defined as the volumetric particle size D84v and the number particle size D84p.

[0204] Using these values, the volumetric granularity distribution index (GSDv) is expressed as (D84v / D16v). 1 / 2 Calculate the number granularity distribution index (GSDp) as (D84p / D16p). 1 / 2 Calculated.

[0205] The average roundness of the colorant particles is preferably 0.94 or more and 1.00 or less, more preferably 0.95 or more and 0.98 or less.

[0206] The roundness of the toner particles is determined by (equivalent circle circumference) / (circumference) [(circumference of a circle with the same projected area as the particle image) / (circumference of the particle projection image)]. Specifically, it is the value obtained by measuring using the method described below.

[0207] First, toner particles, the object of measurement, are attracted and collected to form a flattened flow. A still image of the particles is obtained by momentarily flashing the particle image. The average roundness is then calculated using a flow cytometry particle image analyzer (Sysmex FPIA-3000). The number of samples used to calculate the average roundness is set to 3500.

[0208] It should be noted that when the colorant contains additives, the colorant (developer) to be measured is dispersed in water containing a surfactant, and then subjected to ultrasonic treatment to obtain colorant particles with additives removed.

[0209] (Additives)

[0210] Examples of 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, and MgSO4.

[0211] The surface of inorganic particles used as additives can be hydrophobically treated. Hydrophobic treatment can be performed, for example, by impregnating the inorganic particles with a hydrophobic agent. There are no particular limitations on the hydrophobic agent; examples include silane-based coupling agents, silicone oils, titanate-based coupling agents, and aluminum-based coupling agents. They can be used alone or in combination of two or more.

[0212] The amount of the hydrophobic treatment agent is typically, for example, more than 1 part by mass and less than 10 parts by mass relative to 100 parts by mass of inorganic particles.

[0213] Other examples of additives include resin particles (such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin particles), cleaning and activating agents (such as metal salts of higher fatty acids, such as zinc stearate, and particles of fluorine-based high molecular weight substances).

[0214] The amount of additive used as an external additive is preferably 0.01% to 5% by mass, more preferably 0.01% to 2.0% by mass, relative to the colorant particles.

[0215] (Characteristics of colorants)

[0216] In this embodiment, the maximum endothermic peak temperature of the toner during the first heating, as measured by differential scanning calorimetry (DSC), is preferably 58°C or higher and 75°C or lower. By setting the maximum endothermic peak temperature of the toner to 58°C or higher and 75°C or lower, the low-temperature fixing properties of the toner become good.

[0217] The maximum endothermic peak temperature during the first heating was determined using a differential scanning calorimeter (DSC) as follows.

[0218] A Perkin Elmer differential scanning calorimeter (DSC-7) was used. Temperature calibration of the detector section utilized the melting points of indium and zinc, while thermal calibration utilized the heat of fusion of indium. An aluminum pan was used as the sample, with an empty pan set as a reference. The temperature was increased from room temperature to 150°C at a rate of 10°C / min. The temperature at which the maximum endothermic peak occurred was then determined from the resulting endothermic curve.

[0219] (Method for manufacturing colorants)

[0220] Next, the method for manufacturing the colorant in this embodiment will be described.

[0221] The colorant in this embodiment is obtained by adding an additive to the colorant particles after the colorant particles are manufactured.

[0222] Colorant particles can be manufactured by any of the following methods: dry manufacturing (e.g., mixing and pulverizing) or wet manufacturing (e.g., agglomeration and coagulation, suspension polymerization, dissolution suspension). The manufacturing method of colorant particles is not particularly limited to these methods and can employ well-known methods.

[0223] Among these, from the perspective of ensuring that the micro-regions of crystalline resin meet the above conditions, colorant particles can be obtained by agglomeration and merging.

[0224] Specifically, for example, in the case of manufacturing colorant particles by agglomeration and merging, the colorant particles are manufactured through the following steps:

[0225] Steps for preparing amorphous resin particle dispersions containing amorphous resin particles and crystalline resin particle dispersions containing crystalline resin particles (resin particle dispersion preparation steps).

[0226] The step of agglomerating amorphous resin particles (with colorant, release agent, etc. if necessary) in an amorphous resin particle dispersion (or in a dispersion after mixing colorant dispersion and release agent dispersion as needed) to form the first aggregated particles (the first aggregated particle forming step).

[0227] After obtaining the agglomerated particle dispersion containing the first agglomerated particles, the agglomerated particle dispersion is mixed with an amorphous resin particle dispersion and a crystalline resin particle dispersion (or the agglomerated particle dispersion is mixed with a mixture of an amorphous resin particle dispersion and a crystalline resin particle dispersion), and agglomerated particles are further attached to the surface of the first agglomerated particles. This operation is repeated more than twice to form the second agglomerated particles (the second agglomerated particle formation step).

[0228] After obtaining the agglomerated particle dispersion containing the second agglomerated particle, the agglomerated particle dispersion is mixed with an amorphous resin particle dispersion, and agglomerated in such a way that the amorphous resin particles adhere to the surface of the second agglomerated particle to form the third agglomerated particle (the third agglomerated particle formation step); and

[0229] The dispersion of agglomerated particles containing the third agglomerated particle is heated to fuse / merge the agglomerated particles, followed by a series of steps including rapid cooling, reheating, and slow cooling to form colorant particles (fusion / merging step).

[0230] The following details each step.

[0231] It should be noted that the following description focuses on the method for obtaining colorant particles containing colorant and release agent, but the colorant and release agent are additives used as needed. Of course, other additives besides colorant and release agent can also be used.

[0232] -Preparation steps for resin particle dispersion-

[0233] First, prepare a dispersion of each resin particle (amorphous resin particle dispersion and crystalline resin particle dispersion) containing each resin particle as an adhesive resin, and prepare, for example, a dispersion of colorant particles containing colorant particles and a dispersion of release agent particles containing release agent particles.

[0234] Here, the resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

[0235] Examples of dispersion media used in resin particle dispersions include aqueous media.

[0236] Examples of aqueous media include distilled water, ion-exchanged water, and alcohols. These media can be used individually or in combination.

[0237] Examples of surfactants include: anionic surfactants such as sulfate esters, sulfonates, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyols. Among these, anionic and cationic surfactants are particularly noteworthy. Nonionic surfactants can also be used in combination with anionic or cationic surfactants.

[0238] Surfactants can be used alone or in combination of two or more.

[0239] In resin particle dispersions, common methods for dispersing resin particles in a dispersion medium include using a rotary shear homogenizer or a ball mill, sand mill, or bead mill with a media. Alternatively, depending on the type of resin particles, methods such as phase inversion emulsification can also be used to disperse resin particles in the resin particle dispersion.

[0240] It should be noted that the phase inversion emulsification method is as follows: the resin to be dispersed is dissolved in a hydrophobic organic solvent that can dissolve the resin, an alkali is added to the organic continuous phase (O phase) for neutralization, and then an aqueous medium (W phase) is introduced, thereby converting the resin from W / O to O / W (so-called phase inversion) to make it discontinuous, so that the resin is dispersed in the aqueous medium in particulate form.

[0241] 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.

[0242] It should be noted that the volume average particle size of the resin particles was determined using a particle size distribution measured by a laser diffraction particle size distribution measuring device (e.g., the LA-700 manufactured by Horiba Manufacturing Co., Ltd.). For the defined particle size range (segment), a cumulative volume distribution was plotted from the smallest particle size side, and the particle size at the cumulative 50% point relative to all particles was measured and taken as the volume average particle size D50v. It should also be noted that the volume average particle size of particles in other dispersions was measured in the same manner.

[0243] The content of resin particles in the resin particle dispersion is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less.

[0244] It should be noted that colorant particle dispersions and release agent particle dispersions are prepared in the same manner as resin particle dispersions. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion are the same as those of the colorant particles dispersed in the colorant particle dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0245] -Step 1: Formation of Aggregated Particles-

[0246] Next, the amorphous resin particle dispersion is mixed with the colorant particle dispersion and the release agent particle dispersion.

[0247] Subsequently, amorphous resin particles, colorant particles, and release agent particles are heterogeneously aggregated in the mixed dispersion to form the first aggregated particles with a diameter similar to that of the target colorant particles and containing amorphous resin particles, colorant particles, and release agent particles.

[0248] Specifically, for example, a flocculant is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to acidic (e.g., pH 2 or higher than 5). A dispersing stabilizer is added as needed, and then the mixture is heated to the glass transition temperature of the resin particles (specifically, for example, the glass transition temperature of the resin particles -30°C to -10°C), causing the particles dispersed in the mixed dispersion to agglomerate and form the first agglomerated particles.

[0249] In the first step of forming aggregated particles, for example, the above-mentioned agglomerant can be added at room temperature (e.g., 25°C) while the mixed dispersion is stirred using a rotary shear homogenizer, the pH of the mixed dispersion is adjusted to acidic (e.g., pH 2 or higher than 5), and the above-mentioned heating is performed after adding a dispersion stabilizer as needed.

[0250] Examples of flocculants include surfactants with polarity opposite to that of the surfactants used as dispersants added to the mixed dispersion, inorganic metal salts, and metal complexes with a polarity of two or higher. In particular, when metal complexes are used as flocculants, the amount of surfactant required is reduced, and the charging characteristics are improved.

[0251] Additives that form complexes or similar bonds with the metal ions of the flocculant can be used as needed. Chelating agents are suitable as such additives.

[0252] Examples of inorganic metal salts include calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.

[0253] Water-soluble chelating agents can be used as chelating agents. Examples of chelating agents include tartaric acid, citric acid, gluconic acid and other hydroxycarboxylic acids, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), etc.

[0254] The amount of chelating agent added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less, more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, relative to 100 parts by mass of amorphous resin particles.

[0255] -Step 2 of Aggregate Particle Formation-

[0256] Next, after obtaining the agglomerated particle dispersion containing the first agglomerated particles, the agglomerated particle dispersion is mixed with both an amorphous resin particle dispersion and a crystalline resin particle dispersion. Alternatively, the agglomerated particle dispersion can be mixed with a mixture of the amorphous resin particle dispersion and the crystalline resin particle dispersion.

[0257] Subsequently, the amorphous resin particles and crystalline resin particles are agglomerated on the surface of the first aggregated particles in a dispersion containing the first aggregated particles, amorphous resin particles, and crystalline resin particles.

[0258] Specifically, for example, in the first aggregated particle forming step, after the first aggregated particles reach the target particle size, an amorphous resin particle dispersion and a crystalline resin particle dispersion are added to the first aggregated particle dispersion, and the dispersion is heated below the glass transition temperature of the amorphous resin particles.

[0259] Repeat the agglomeration operation more than twice to form a second agglomerated particle.

[0260] -Step 3: Formation of Aggregated Particles-

[0261] After obtaining the agglomerated particle dispersion containing the second agglomerated particle, the agglomerated particle dispersion is mixed with the amorphous resin particle dispersion.

[0262] Subsequently, the amorphous resin particles are agglomerated on the surface of the second agglomerated particles in a dispersion containing the second agglomerated particles and amorphous resin particles.

[0263] Specifically, for example, in the second aggregated particle formation step, after the second aggregated particles reach the target particle size, an amorphous resin particle dispersion is added to the second aggregated particle dispersion, and the dispersion is heated below the glass transition temperature of the amorphous resin particles.

[0264] Then adjust the pH of the dispersion to stop the aggregation process.

[0265] -Merge / merge steps-

[0266] Next, the dispersion of the third aggregated particles, in which the third aggregated particles are dispersed, is heated, for example, to a temperature above the glass transition temperature of the amorphous resin particles (e.g., a temperature 10°C to 30°C higher than the glass transition temperature of the amorphous resin particles), causing the aggregated particles to fuse / merge and form colorant particles.

[0267] Here, after fusing / merging the agglomerated particles using heating, the temperature can be cooled to 30°C at a rate of 5°C / min to 40°C / min. By subjecting the particles to quenching after the third agglomerated particle formation step, shrinkage of the toner particle surface easily occurs, making them prone to cracking. It is presumed that by performing the quenching step under the above conditions, cracks are likely to form from the interior of the toner particles toward the toner surface.

[0268] Next, the temperature is raised again at a rate of 0.1°C / min to 2°C / min, and held at a temperature above the melting temperature of the crystalline resin (-5°C) for at least 10 minutes. Then, the temperature is slowly cooled at a rate of 0.1°C / min to 1°C / min, thereby causing the crystalline resin microdomains to grow along the crack direction. The crystalline resin microdomains grow from the inside of the colorant particles toward the surface, thus satisfying the above conditions.

[0269] Furthermore, for example, when heating to above the melting temperature of the release agent during reheating, the likelihood of release agent micro-regions growing near the surface of the colorant particles increases. Therefore, the heating temperature during reheating is preferably raised to at least 5°C above the melting temperature of the crystalline resin and below the melting temperature of the release agent.

[0270] After the above steps, colorant particles are obtained.

[0271] It should be noted that, in addition to the manufacturing method of colorant particles based on the above-mentioned agglomeration method, if the above-mentioned rapid cooling, reheating and slow cooling are performed after the colorant particles are made, the crystalline resin microregions will also meet the above conditions.

[0272] Here, after the fusion / merging step is completed, the toner particles formed in the solution are subjected to a known washing step, a solid-liquid separation step, and a drying step to obtain toner particles in a dry state.

[0273] Regarding the cleaning process, from a rechargeability perspective, displacement cleaning using ion-exchange water can be fully implemented. Furthermore, there are no particular limitations on the solid-liquid separation process; from a productivity perspective, methods such as vacuum filtration and pressure filtration can be employed. Additionally, there are no particular limitations on the drying method; from a productivity perspective, methods such as freeze drying, airflow drying, fluidized bed drying, and vibrating fluidized bed drying can be implemented.

[0274] Then, for example, an additive is added to the obtained dried colorant particles and mixed, thereby producing the colorant of this embodiment. Mixing can be performed using, for example, a V-type mixer, a Henschel mixer, a Rodier mixer, etc. Furthermore, coarse particles of the colorant can be removed as needed using a vibrating screen, a pneumatic screen, etc.

[0275] <Electrostatic Image Developer>

[0276] The electrostatic image developer of this embodiment includes at least the toning agent of this embodiment.

[0277] The electrostatic image developer of this embodiment can be a single-component developer containing only the toner of this embodiment, or it can be a two-component developer formed by mixing the toner with a carrier.

[0278] There are no particular limitations on the carrier, and well-known carriers can be cited as examples. Examples of carriers include: coated carriers in which a core material formed of magnetic powder is coated with a coating resin; magnetic powder dispersion carriers in which magnetic powder is dispersed and mixed in a matrix resin; resin impregnated carriers in which porous magnetic powder is impregnated with resin; and so on.

[0279] It should be noted that magnetic powder dispersion carriers and resin impregnation carriers can also be carriers made by using the constituent particles of the carrier as core material and coating them with coating resin.

[0280] Examples of magnetic powders include magnetic metals such as iron, nickel, and cobalt, as well as magnetic oxides such as ferrite and magnetite.

[0281] 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-acrylate copolymer, pure silicone resins or their modifications comprising organosiloxane bonds, fluoropolymers, polyesters, polycarbonates, phenolic resins, epoxy resins, etc.

[0282] It should be noted that conductive particles and other additives may also be included in the coating resin and the matrix resin.

[0283] Examples of conductive particles include metals such as gold, silver, and copper, as well as carbon black, titanium dioxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0284] Here, in order to coat the core material with a coating resin, methods such as dissolving the coating resin and, if necessary, various additives in a suitable solvent and using the resulting coating layer forming solution for coating can be cited. There are no particular limitations on the solvent; it can be selected considering the coating resin used, its coating suitability, etc.

[0285] Specific resin coating methods include: impregnation, in which the core material is impregnated in a coating layer forming solution; spraying, in which the coating layer forming solution is sprayed onto the surface of the core material; fluidized bed method, in which the coating layer forming solution is sprayed while the core material is suspended by flowing air; kneading coating machine method, in which the core material of the carrier is mixed with the coating layer forming solution in a kneading coating machine, and then the solvent is removed; and so on.

[0286] The mixing ratio (mass ratio) of the toner and carrier in the two-component developer is preferably toner:carrier = 1:100 to 30:100, more preferably 3:100 to 20:100.

[0287] <Image forming apparatus / Image forming method>

[0288] The image forming apparatus / image forming method of this embodiment will be described.

[0289] The image forming apparatus of this embodiment includes: an image holder; a charging mechanism that charges the surface of the image holder; an electrostatic image forming mechanism that forms an electrostatic image on the charged surface of the image holder; a developing mechanism that stores an electrostatic image developer and develops the electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer; a transfer mechanism that transfers the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing mechanism that fixes the toner image transferred to the surface of the recording medium. Furthermore, the electrostatic image developer of this embodiment is used as the electrostatic image developer.

[0290] An image forming method (the image forming method of this embodiment) is performed using the image forming apparatus of this embodiment. The method includes the following steps: a charging step, in which the surface of an image holder is charged; an electrostatic image forming step, in which an electrostatic image is formed on the charged surface of the image holder; a developing step, in which the electrostatic image formed on the surface of the image holder is developed into a toner image using the electrostatic image developer of this embodiment; a transfer step, in which the toner image formed on the surface of the image holder is transferred to the surface of a recording medium; and a fixing step, in which the toner image transferred to the surface of the recording medium is fixed.

[0291] The image forming apparatus of this embodiment is applicable to the following known image forming apparatuses: a direct transfer method apparatus that directly transfers a toner image formed on the surface of an image holder to a recording medium; an intermediate transfer method apparatus that first transfers a toner image formed on the surface of an image holder to the surface of an intermediate transfer body, and then transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium a second time; an apparatus equipped with a cleaning mechanism for cleaning the surface of the image holder after the toner image is transferred but before charging; an apparatus equipped with a de-energizing mechanism for irradiating the surface of the image holder with de-energizing light to de-energize it after the toner image is transferred but before charging; and so on.

[0292] In the case of an intermediate transfer method apparatus, the transfer mechanism may, for example, employ a configuration having the following components: an intermediate transfer body that transfers a toner image to a surface; a primary transfer mechanism that transfers a toner image formed on the surface of an image holder to the surface of the intermediate transfer body in one step; and a secondary transfer mechanism that transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium in a second step.

[0293] It should be noted that, in the image forming apparatus of this embodiment, the portion including the developing mechanism may also be a cartridge structure (processing cartridge) that is installed and removed from the image forming apparatus. As a processing cartridge, for example, a processing cartridge having a developing mechanism that stores the electrostatic image developer of this embodiment is suitable.

[0294] The following shows an example of the image forming apparatus of this embodiment, but it is not limited thereto. It should be noted that only the main parts shown in the figures are described, and the description of other parts is omitted.

[0295] Figure 1 This is a schematic configuration diagram of the image forming apparatus according to this embodiment.

[0296] Figure 1 The image forming apparatus shown includes four image forming units 10Y, 10M, 10C, and 10K (image forming mechanisms) of an electrophotographic method that outputs images of yellow (Y), magenta (M), cyan (C), and black (K) based on color image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side-by-side at a predetermined distance from each other in the horizontal direction. It should be noted that these units 10Y, 10M, 10C, and 10K can also be processing boxes that are mounted and removed from the image forming apparatus.

[0297] Above each of the attached figures for units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20, serving as an intermediate transfer body, extends through each unit. The intermediate transfer belt 20 is wound around a drive roller 22, which is arranged separately from each other in the left-to-right direction shown in the figures, and a support roller 24, which is in contact with the inner surface of the intermediate transfer belt 20, causing it to move in the direction from the first unit 10Y to the fourth unit 10K. It should be noted that the support roller 24 applies force in a direction separate from the drive roller 22 via a spring (not shown), applying tension to the intermediate transfer belt 20 wound around both. Furthermore, an intermediate transfer body cleaning device 30, opposite to the drive roller 22, is provided on the image holding side of the intermediate transfer belt 20.

[0298] In addition, the four color toners—yellow, magenta, cyan, and black—stored in the toner cartridges 8Y, 8M, 8C, and 8K are supplied to the developing units (developing mechanisms) 4Y, 4M, 4C, and 4K of each unit 10Y, 10M, 10C, and 10K, respectively.

[0299] Units 1 through 4, 10Y, 10M, 10C, and 10K, have the same configuration. Therefore, this description will focus on unit 10Y, which forms the yellow image and is located upstream of the intermediate transfer belt in the direction of travel. It should be noted that for parts that are equivalent to unit 10Y, reference symbols with magenta (M), cyan (C), and black (K) are used instead of yellow (Y), thus the description of units 2 through 4, 10M, 10C, and 10K, is omitted.

[0300] Unit 10Y has a photoreceptor 1Y that functions as an image holder. Around the photoreceptor 1Y are arranged in sequence: a charging roller (an example of a charging mechanism) 2Y, which charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic image forming mechanism) 3, which uses a laser line 3Y to expose the charged surface based on a color separation image signal to form an electrostatic image; a developing device (an example of a developing mechanism) 4Y, which supplies the charged toner to the electrostatic image to develop the electrostatic image; a primary transfer roller 5Y (an example of a primary transfer mechanism), which transfers the developed toner image onto an intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning mechanism) 6Y, which removes the toner remaining on the surface of the photoreceptor 1Y after the primary transfer.

[0301] It should be noted that the primary transfer roller 5Y is positioned inside the intermediate transfer belt 20, opposite to the photosensitive element 1Y. Furthermore, each of the primary transfer rollers 5Y, 5M, 5C, and 5K is connected to a bias power supply (not shown) that applies a primary transfer bias voltage. The transfer bias voltage applied to each primary transfer roller is changed by a control unit (not shown).

[0302] The following explains the action of forming the yellow image in Unit 1, 10Y.

[0303] First, before the operation, the surface of the photoreceptor 1Y is charged to a potential of -600V to -800V using the charging roller 2Y.

[0304] Photoreceptor 1Y has a high conductivity (e.g., a volume resistivity of 1×10⁻⁶ at 20°C). -6 A photosensitive layer is deposited on a substrate (Ωcm or less). This photosensitive layer typically has high resistance (the resistance of common resins), but it has the property that the resistivity of the portion irradiated by the laser line 3Y changes when the laser line 3Y is irradiated. Therefore, based on the yellow image data sent by the control unit (not shown), the laser line 3Y is output to the surface of the charged photoreceptor 1Y by the exposure apparatus 3. The laser line 3Y irradiates the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic image of a yellow image pattern on the surface of the photoreceptor 1Y.

[0305] An electrostatic image is an image formed on the surface of a photoreceptor 1Y by charging. It is a so-called negative latent image, which is formed as follows: the resistivity of the irradiated part of the photosensitive layer is reduced by using a laser line 3Y, causing the charged charge on the surface of the photoreceptor 1Y to flow; on the other hand, the charge remains in the part that is not irradiated by the laser line 3Y, thereby forming the negative latent image.

[0306] The electrostatic image formed on the photoreceptor 1Y rotates to a predetermined developing position as the photoreceptor 1Y rotates. At this developing position, the electrostatic image on the photoreceptor 1Y is visualized (developed) into a toner image by the developing device 4Y.

[0307] The developing apparatus 4Y stores an electrostatic image developer, for example, containing at least a yellow toner and a carrier. The yellow toner, inside the developing apparatus 4Y, becomes triboelectrically charged through agitation, acquiring a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y, and is held on a developer roller (an example of a developer holder). The surface of the photoreceptor 1Y then passes through the developing apparatus 4Y, whereby the yellow toner electrostatically adheres to the de-charged latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed using the yellow toner. The photoreceptor 1Y, with the yellow toner image formed, continues to rotate at a preset speed, conveying the developed toner image on the photoreceptor 1Y to a preset primary transfer position.

[0308] When the yellow toner image on the photoreceptor 1Y is transferred to the primary transfer position, a primary transfer bias is applied to the primary transfer roller 5Y. The electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image, transferring the toner image on the photoreceptor 1Y onto the intermediate transfer belt 20. The applied transfer bias at this time has a polarity (+) opposite to the polarity (-) of the toner, for example, it is controlled to +10μA by a control unit (not shown) in the first unit 10Y.

[0309] On the other hand, the toner remaining on the photoreceptor 1Y is removed and recycled using the photoreceptor cleaning device 6Y.

[0310] In addition, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K after 10M in Unit 2 is also controlled according to Unit 1.

[0311] In this way, the intermediate transfer belt 20, which has transferred the yellow toner image using the first unit 10Y, is sequentially transmitted through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are transferred multiple times in an overlay manner.

[0312] The intermediate transfer belt 20, which has undergone multiple transfer of four toner images via units 1 to 4, reaches the secondary transfer section. This secondary transfer section consists of the intermediate transfer belt 20, a support roller 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roller (an example of a secondary transfer mechanism) 26 disposed on the image holding side of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is fed to the gap between the secondary transfer roller 26 and the intermediate transfer belt 20 at a predetermined time by a supply member, and a secondary transfer bias is applied to the support roller 24. The applied transfer bias is of the same polarity (-) as the toner, and the electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image from the intermediate transfer belt 20 to the recording paper P. It should be noted that the secondary transfer bias is determined based on the resistance detected by a resistance detection mechanism (not shown) that detects the resistance of the secondary transfer section, and the voltage is controlled.

[0313] Then, the recording paper P is fed into the pressing part (engaging part) of a pair of fixing rollers in the fixing device (an example of a fixing mechanism) 28, and the toner image is fixed on the recording paper P to form a fixed image.

[0314] Recording paper P used for transferring toner images can include, for example, ordinary paper used in photocopiers and printers for electrophotographic methods. Regarding recording media, in addition to recording paper P, examples include OHP transparent film.

[0315] 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, such as coated paper or art paper for printing, which are obtained by coating the surface of ordinary paper with resin or the like.

[0316] The recording paper P, which has been fixed with a color image, is sent to the discharge section, thus ending a series of color imaging actions.

[0317] <Treatment Box / Toner Box>

[0318] The processing box of this embodiment will be described.

[0319] The processing box of this embodiment is a processing box that is installed and removed from the image forming apparatus. It has a developing mechanism that stores the electrostatic image developer of this embodiment and uses the electrostatic image developer to develop the electrostatic image formed on the surface of the image holder into a toner image.

[0320] It should be noted that the processing box of this embodiment is not limited to the above configuration, and may also be configured to include a developing device and, if necessary, at least one of other mechanisms selected from an image holder, a charging mechanism, an electrostatic image forming mechanism, and a transfer mechanism.

[0321] The following shows an example of the processing box of this embodiment, but it is not limited thereto. It should be noted that only the main parts shown in the figure are described, and the description of other parts is omitted.

[0322] Figure 2 This is a schematic configuration diagram showing the processing box of this embodiment.

[0323] Figure 2 The processing cartridge 200 shown is constructed, for example, by using a housing 117 having a mounting rail 116 and an opening 118 for exposure to integrally combine and hold the photosensitive element 107 (an example of an image holder) with the charging roller 108 (an example of a charging mechanism), the developing device 111 (an example of a developing mechanism), and the photosensitive element cleaning device 113 (an example of a cleaning unit) surrounding the photosensitive element 107, thus forming an ink cartridge.

[0324] It should be noted that, Figure 2 In the diagram, 109 represents an exposure device (an example of an electrostatic image forming mechanism), 112 represents a transfer device (an example of a transfer mechanism), 115 represents a fixing device (an example of a fixing mechanism), and 300 represents recording paper (an example of a recording medium).

[0325] Next, the colorant box of this embodiment will be described.

[0326] The toner cartridge in this embodiment is a toner cartridge that stores the toner of this embodiment and is attached to and removed from the image forming apparatus. The toner cartridge stores replenishment toner for supplying to the developing unit provided within the image forming apparatus.

[0327] It should be noted that, Figure 1 The image forming apparatus shown is configured with toner cartridges 8Y, 8M, 8C, and 8K for loading and unloading. The developing units 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to each developing unit (color) via toner supply tubes (not shown). Furthermore, if the toner stored in the toner cartridge is insufficient, the toner cartridge is replaced.

[0328] Example

[0329] The following examples and comparative examples illustrate this embodiment in more detail, but this embodiment is not limited to these examples. It should be noted that, unless otherwise stated, "parts" and "%" are used as a basis for measuring quantity.

[0330] <Preparation of Amorphous Resins>

[0331] (Preparation of amorphous polyester resin (A))

[0332] ·Terephthalic acid: 70 parts

[0333] Fumaric acid: 30 parts

[0334] Ethylene glycol: 41 parts

[0335] ·1,5-Pentanediol: 48 parts

[0336] The above materials were added to a 5-liter flask equipped with a stirrer, a nitrogen inlet pipe, a temperature sensor, and a distillation column. The temperature was raised to 220°C over 1 hour under a nitrogen flow. One part tetraethoxytitanium was added for every 100 parts of the above materials. While distilling to remove the generated water, the temperature was raised to 240°C over 0.5 hours. The dehydration condensation reaction was continued at this temperature for 1 hour, after which the reactants were cooled. This process synthesized an amorphous polyester resin (A) with a weight-average molecular weight of 96,000 and a glass transition temperature of 61°C.

[0337] <Preparation of Amorphous Resin Particle Dispersions>

[0338] (Preparation of amorphous polyester resin particle dispersion (A1))

[0339] 40 parts of ethyl acetate and 25 parts of 2-butanol were added to a container equipped with a temperature control mechanism and a nitrogen purging mechanism to prepare a mixed solvent. Then, 100 parts of amorphous polyester resin (A) were slowly added to dissolve it. A 10% ammonia solution (equivalent to 3 times the amount of the resin in molar ratio relative to the acid value) was added, and the mixture was stirred for 30 minutes. Next, the container was purged with dry nitrogen to maintain the temperature at 40°C. While stirring the mixture, 400 parts of ion-exchanged water were added dropwise at a rate of 2 parts / minute to emulsify the mixture. After the addition was complete, the emulsion was returned to 25°C to obtain a resin particle dispersion containing resin particles with a volume average particle size of 190 nm. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20%, thus preparing an amorphous polyester resin particle dispersion (A1).

[0340] <Preparation of Crystalline Resins>

[0341] (Preparation of crystalline polyester resin (B))

[0342] ·1,10-decanedicarboxylic acid: 265 parts

[0343] ·1,6-Hexanediol: 168 parts

[0344] • Dibutyltin oxide (catalyst): 0.3 parts by weight

[0345] The above-mentioned components were added to a heated and dried three-necked flask. The air inside the flask was then purged with nitrogen under reduced pressure to create an inert atmosphere. The mixture was mechanically stirred and refluxed at 180°C for 5 hours. Subsequently, the temperature was slowly increased to 230°C under reduced pressure and stirred for 2 hours until a viscous consistency was achieved. The reaction was then stopped by air cooling. Molecular weight determination (converted from polystyrene) revealed that the obtained "crystalline polyester resin (B)" had a weight-average molecular weight (Mw) of 12700 and a melting temperature of 73°C.

[0346] <Preparation of Crystalline Polyester Resin Particle Dispersion>

[0347] (Preparation of crystalline polyester resin particle dispersion (B1))

[0348] Using 90 parts by weight of crystalline polyester resin (B), 1.8 parts by weight of ionic surfactant NEOGEN RK (Daiichi Kogyo Pharmaceutical), and 210 parts by weight of ion-exchanged water, the mixture was heated to 120°C and thoroughly dispersed using an IKA-made ULTRA-TURRAX T50 homogenizer. Then, the dispersion was carried out for 1 hour using a pressure-dispensing Gaulin homogenizer to prepare a crystalline polyester resin particle dispersion (B1) with a volume average particle size of 190 nm and a solid content of 20 parts by weight.

[0349] (Preparation of colorant particle dispersion)

[0350] • Carbon black (manufactured by Cabot, Regal 330): 50 parts

[0351] • Ionic surfactant NEOGEN RK (Daiichi Kogyo Pharmaceutical): 5 parts

[0352] • Ion-exchanged water: 193 samples

[0353] The above components were mixed and treated with Ultimaizer (manufactured by Sugino Machine) at 240 MPa for 10 minutes to prepare a colorant particle dispersion (solid component concentration: 20%).

[0354] <Preparation of Release Agent Particle Dispersion>

[0355] (Preparation of release agent particle dispersion (W1))

[0356] • Ester-based wax (WEP-5 manufactured by Nippon Yu Co., Ltd., melting temperature 82°C): 100 parts

[0357] • Anionic surfactant (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., NEOGEN RK): 1 part

[0358] • Ion-exchanged water: 350 parts

[0359] The above materials were mixed, heated to 100°C, dispersed using a homogenizer (ULTRA-TURRAXT50 manufactured by IKA), and then dispersed using a Manton Gaulin high-pressure homogenizer (manufactured by Gaulin) to obtain a release agent particle dispersion (W1) (20% solid content) containing release agent particles with a volume average particle size of 220 nm.

[0360] (Preparation of release agent particulate dispersion (W2))

[0361] • Solid paraffin wax (HNP-0190, manufactured by Nippon Seika Co., Ltd., melting temperature 89°C): 100 parts

[0362] • Anionic surfactant (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., NEOGEN RK): 1 part

[0363] • Ion-exchanged water: 350 parts

[0364] The above materials were mixed, heated to 100°C, dispersed using a homogenizer (ULTRA-TURRAX T50 manufactured by IKA), and then dispersed using a Manton Gaulin high-pressure homogenizer (manufactured by Gaulin) to obtain a release agent particle dispersion (W2) containing release agent particles with a volume average particle size of 220 nm (solid content 20%).

[0365] (Preparation of release agent particulate dispersion (W3))

[0366] • Polyethylene wax (manufactured by Toyo ADL Co., Ltd., PW600, melting point 91℃: 100 parts)

[0367] • Anionic surfactant (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., NEOGEN RK): 1 part

[0368] • Ion-exchanged water: 350 parts

[0369] The above materials were mixed, heated to 100°C, dispersed using a homogenizer (ULTRA-TURRAX T50 manufactured by IKA), and then dispersed using a Manton Gaulin high-pressure homogenizer (manufactured by Gaulin) to obtain a release agent particle dispersion (W3) containing release agent particles with a volume average particle size of 220 nm (solid content 20%).

[0370] <Example 1>

[0371] -Production of Toner Particles-

[0372] • Ion-exchanged water: 215 parts

[0373] • Amorphous polyester resin particle dispersion (A1): 167 parts

[0374] • Crystalline polyester resin particle dispersion (B1): 27 parts

[0375] • Release agent dispersion (W1): 40 parts

[0376] • Colorant dispersion: 20 parts

[0377] • Anionic surfactant (Daiichi Kogyo Pharmaceutical Co., Ltd.: NEOGEN RK, 20%): 2.8 parts

[0378] The above components were added to a 3-liter reaction vessel equipped with a thermometer, pH meter, and stirrer. The temperature was controlled externally using a heating mantle, and maintained at 30°C and 150 rpm for 30 minutes. Subsequently, 0.3N nitric acid aqueous solution was added to adjust the pH to 3.0 for the coagulation step.

[0379] While dispersing using a homogenizer (ULTRA-TURRAX T50, manufactured by IKA Japan), an aqueous solution of PAC (30% powder, manufactured by Oji Paper Co., Ltd.) was added, consisting of 0.7 parts dissolved in 7 parts of deionized water. The mixture was then heated to 50°C while stirring to produce agglomerated particles forming the core (hereinafter referred to as "core agglomerated particles"). The particle size of the core agglomerated particles was measured using a Coulter Multisizer II (pore size: 50 μm, manufactured by Coulter), and the volume average particle size (D50v) was 4.9 μm. Subsequently, a mixture of 10 parts amorphous polyester resin particle dispersion (A1) and 10 parts crystalline polyester resin particle dispersion (B1) was added. After 30 minutes, a further mixture of 10 parts amorphous polyester resin dispersion (A1) and 10 parts crystalline polyester resin particle dispersion (B1) was added.

[0380] It should be noted that this additional addition was repeated a total of 4 times. That is, the mixture of 10 parts of amorphous polyester resin particle dispersion (A1) and 10 parts of crystalline polyester resin particle dispersion (B1) was added 4 times.

[0381] Finally, 20 parts of amorphous polyester resin particle dispersion (A1) are added to allow the amorphous polyester resin particles to adhere to the surface of the aggregated particles.

[0382] Next, 20 parts of a 10% aqueous solution of NTA (nitrotriacetic acid) metal salt (Chelest70: manufactured by Chelest Co., Ltd.) were added, and the pH was adjusted to 9.0 using a 1N sodium hydroxide aqueous solution. The temperature was then increased to 90°C at a rate of 0.05°C / min, held at 90°C for 3 hours, and then cooled to 30°C at a rate of 15°C / min (first cooling). The temperature was then increased to 80°C at a rate of 0.2°C / min (this temperature is above the melting temperature of the crystalline resin -5°C) (reheating), held for 30 minutes, and then slowly cooled to 30°C at a rate of 0.5°C / min (second cooling). The mixture was then filtered to obtain coarse colorant particles. The mixture was further subjected to repeated redispersion and filtration using ion-exchange water. After washing until the conductivity of the filtrate reached below 20 μS / cm, it was vacuum dried in an oven at 40°C for 5 hours to obtain colorant particles with a volume average particle size (D50v) of 5.8 μm.

[0383] -Making of Toners-

[0384] For every 100 parts of the obtained colorant particles, 1.5 parts of hydrophobic silica (manufactured by NIPPONAEROSIL, RY50) were mixed at 10,000 rpm for 30 seconds using a sample mill. The mixture was then sieved using a vibrating sieve with a mesh size of 45 μm to obtain the colorant.

[0385] <Examples 2-27>

[0386] When the core aggregated particles reach the particle size listed in Table 1, additional amorphous polyester resin particle dispersion (A1) and crystalline polyester resin particle dispersion (B1) are added, and the colorant particles are prepared in the same manner as in Example 1.

[0387] The cooling rate for the first cooling, the holding temperature after reheating, and the cooling rate for the second cooling are implemented as shown in Table 1.

[0388] It should be noted that in Example 3, release agent particle dispersion (W2) was used instead of release agent particle dispersion (W1) used in Example 1 to prepare colorant particles.

[0389] In addition, in Example 4, release agent particle dispersion (W3) was used instead of release agent particle dispersion (W1) used in Example 1 to prepare colorant particles.

[0390] <Example 28>

[0391] 680 parts of amorphous polyester resin (A), 200 parts of crystalline polyester resin (B), 40 parts of carbon black (Regal 330), and 80 parts of ester wax (WEP-5) were premixed thoroughly using a Henschel mixer, melt-mixed using a two-roll mill, cooled, and then micronized using a jet mill. The mixture was further classified twice using an air classifier to obtain colorant particles.

[0392] The colorant particles were heated to 70°C (a temperature above the melting temperature of crystalline resin by 5°C) and held for 20 minutes. They were then rapidly cooled to 30°C by air cooling at a rate of 15°C / min. The mixture was then reheated to 70°C, held for 30 minutes, and then slowly cooled to 30°C by air cooling at a rate of 0.5°C / min to obtain the colorant particles.

[0393] <Example 29>

[0394] (Preparation of polyester prepolymer)

[0395] Bisphenol A-ethylene oxide adduct: 182 parts

[0396] Bisphenol A-propylene oxide adduct: 21 parts

[0397] ·Terephthalic acid: 7 parts

[0398] • Isophthalic acid: 85 parts

[0399] The monomers were added to a well-dried, nitrogen-replaced three-necked flask and heated to 180°C under nitrogen atmosphere to dissolve them, followed by thorough mixing. After adding 0.4 parts of dibutyltin oxide, the temperature was raised to 205°C and maintained at this temperature while the reaction proceeded. Small samples were taken midway through the reaction to determine the molecular weight, and the reaction was controlled by adjusting the temperature or recovering moisture under reduced pressure to obtain the desired condensate. Then, after cooling to 175°C, 8 parts of phthalic anhydride were added, and the reaction was carried out with stirring under reduced pressure for 3 hours.

[0400] In another three-necked flask that has been well dried and substituted with N2, 200 parts of the condensate obtained above, 15 parts of isophorone diisocyanate, and 285 parts of ethyl acetate were added to the container. The mixture was heated at 70°C for 5 hours while being purged with N2 to obtain an isocyanate-based polyester prepolymer (hereinafter referred to as "isocyanate-modified polyester prepolymer") (solids concentration 43%), which is used as an amorphous resin.

[0401] (Preparation of ketoimine compounds)

[0402] · Methyl ethyl ketone: 20 parts

[0403] • Isophorone diamine: 15 parts

[0404] The above materials were added to a container and stirred while heated at 58°C to obtain a ketimine compound.

[0405] (Preparation of black pigment dispersion for oil phase liquid)

[0406] • Carbon black (manufactured by Cabot, Regal 330): 15 parts

[0407] Ethyl acetate: 65 parts

[0408] Solsperse 5000 (manufactured by Zeneca): 1.2 parts

[0409] The above components are mixed and dissolved / dispersed using a sand mill to obtain a black pigment dispersion for oil phase liquid.

[0410] (Preparation of release agent dispersion for oil phase liquid)

[0411] • Ester-based wax (manufactured by Nippon Yu Co., Ltd., WEP-5 melting temperature 82°C): 20 parts

[0412] Ethyl acetate: 220 parts

[0413] The above components were wet-milled using a microsphere disperser (DCP mill) at a temperature of 18°C ​​to obtain an oil phase liquid release agent dispersion.

[0414] (Preparation of oil-phase liquids)

[0415] • Black pigment dispersion for oil phase liquid: 32 parts

[0416] • Bentonite (manufactured by Wako Pure Chemical Industries, Ltd.): 8 parts

[0417] Ethyl acetate: 58 parts

[0418] Add the above ingredients and mix thoroughly. Add the following to the resulting mixture:

[0419] • Amorphous polyester resin A: 112 parts

[0420] • Crystalline polyester resin B: 28 parts

[0421] • Release agent dispersion for oil phase liquid: 75 parts

[0422] Stir thoroughly to prepare the oil phase liquid.

[0423] (Preparation of styrene-acrylic resin particle dispersion (1))

[0424] Styrene: 75 parts

[0425] • n-Butyl acrylate: 115 parts

[0426] • Methacrylic acid: 75 parts

[0427] • Polyoxyethylene methacrylate sulfate Na (Eleminol RS-30, manufactured by Sanyo Chemical Industry Co., Ltd.): 8 parts

[0428] • Dodecanethiol: 4 parts

[0429] Add the above components to a refluxing reaction vessel and mix thoroughly. Quickly add 800 parts of ion-exchanged water and 1.2 parts of ammonium persulfate to the mixture, and disperse and emulsify using a homogenizer (IKA ULTRA-TURRAX T50) while maintaining the mixture below room temperature to form a white emulsion. While supplying nitrogen gas, raise the temperature of the system to 70°C with stirring, and maintain this temperature for 5 hours to continue emulsion polymerization. Then, slowly add 18 parts of a 1% ammonium persulfate aqueous solution, and maintain the temperature at 70°C for 2 hours to complete the polymerization.

[0430] (Preparation of aqueous solution)

[0431] • Styrene-acrylic resin particle dispersion (1): 50 parts

[0432] • 2% aqueous solution of Cellogen BS-H (CMC, Daiichi Kogyo Pharmaceutical Co., Ltd.): 170 parts

[0433] • Anionic surfactant (Dowfax 2A1, manufactured by Dow): 3 parts

[0434] • Ion-exchanged water: 230 parts

[0435] The above components are thoroughly mixed to form an aqueous phase solution.

[0436] • Oil phase liquid: 370 parts

[0437] • Isocyanate-modified polyester prepolymer: 25 parts

[0438] • Ketoimine compounds: 1.5 parts

[0439] The above components were added to a round-bottom stainless steel flask and stirred for 2 minutes using a homogenizer (ULTRA-TURRAX: manufactured by IKA) to prepare a mixed oil phase. Then, 900 parts of an aqueous phase were added to the flask, and the mixture was rapidly emulsified using a homogenizer (8500 rpm) for approximately 2 minutes. Next, the emulsion was stirred for about 15 minutes at ambient temperature and atmospheric pressure (1 atmosphere) using an impeller-type stirrer to induce particle formation and urea modification of the polyester resin. Subsequently, the mixture was stirred at a speed of 2 m... 3Nitrogen is blown into the suspension at a rate of / h while the solvent is removed by distillation under reduced pressure or by removal under normal pressure. At the same time, the mixture is stirred at 75°C for 8 hours to complete the urea modification reaction.

[0440] It was then rapidly cooled to 30°C at a rate of 15°C / min, and then reheated to 90°C and held for 30 min. After that, it was slowly cooled to 30°C at a rate of 0.5°C / min.

[0441] After cooling, the suspension of generated particles was removed and thoroughly washed with ion-exchanged water. Solid-liquid separation was then performed using a Buchner funnel filter. The particles were then re-dispersed in ion-exchanged water at 35°C and washed for 15 minutes with stirring. This washing process was repeated several times, followed by solid-liquid separation using a Buchner funnel filter. The resulting product was then freeze-dried under vacuum to obtain the colorant particles.

[0442] For every 100 parts by weight of the obtained colorant particles, 1.5 parts by weight of hydrophobic silica (NIPPONAEROSIL, RY50) and 1.0 parts by weight of hydrophobic titanium dioxide (NIPPONAEROSIL, T805) were mixed at 10,000 rpm for 30 seconds using a sample mill. The mixture was then sieved using a vibrating screen with a 45 μm mesh to produce colorant particles.

[0443] <Comparative Example 1: Conventional Toning Agent>

[0444] -Production of Toner Particles-

[0445] • Ion-exchanged water: 215 parts

[0446] • Amorphous polyester resin particle dispersion (A1): 127 parts

[0447] • Crystalline polyester resin particle dispersion (B1): 67 parts

[0448] • Release agent dispersion (W1): 40 parts

[0449] • Colorant dispersion: 20 parts

[0450] • Anionic surfactant (Daiichi Kogyo Pharmaceutical Co., Ltd.: NEOGEN RK, 20%): 2.8 parts

[0451] The above components were added to a 3-liter reaction vessel equipped with a thermometer, pH meter, and stirrer. The temperature was controlled externally using a heating mantle, and maintained at 30°C and 150 rpm for 30 minutes. Subsequently, 0.3N nitric acid aqueous solution was added to adjust the pH to 3.0 for the coagulation step.

[0452] While dispersing using a homogenizer (ULTRA-TURRAX T50, manufactured by IKA Japan), an aqueous solution of PAC (30% powder, manufactured by Oji Paper Co., Ltd.) was added, dissolved in 7 parts of deionized water. The mixture was then heated to 50°C while stirring, and the particle size was measured using a Coulter Multisizer II (50 μm pore size, manufactured by Coulter), resulting in a volume average particle size of 4.9 μm. Subsequently, 100 parts of an amorphous polyester resin particle dispersion (A1) were added to adhere the amorphous polyester resin particles to the surface of the aggregated particles.

[0453] Next, 20 parts of a 10% aqueous solution of NTA (nitrotriacetic acid) metal salt (Chelest70: manufactured by Chelest Co., Ltd.) were added, and the pH was adjusted to 9.0 using a 1N sodium hydroxide aqueous solution. The temperature was then increased to 90°C at a rate of 0.05°C / min, held at 90°C for 3 hours, and then cooled to 30°C at a rate of 15°C / min. Subsequently, the temperature was increased to 80°C at a rate of 0.2°C / min (this temperature is above the melting temperature of the crystalline resin by 5°C), held for 30 minutes, and then rapidly cooled to 30°C at a rate of 15°C / min. The mixture was then filtered to obtain coarse colorant particles. These particles were further redispersed and filtered repeatedly using deionized water, and washed until the conductivity of the filtrate reached below 20 μS / cm. Finally, the mixture was vacuum dried in an oven at 40°C for 5 hours to obtain colorant particles with a volume average particle size of 5.8 μm.

[0454] -Making of Toners-

[0455] For every 100 parts of the obtained colorant particles, 1.5 parts of hydrophobic silica (manufactured by NIPPONAEROSIL, RY50) were mixed at 10,000 rpm for 30 seconds using a sample mill. The mixture was then sieved using a vibrating sieve with a mesh size of 45 μm to obtain the colorant.

[0456] <Comparative Example 2>

[0457] 680 parts of amorphous polyester resin (A), 200 parts of crystalline polyester resin (B), 40 parts of carbon black (Regal 330), and 80 parts of ester wax (WEP-5) were premixed thoroughly using a Henschel mixer, and then melt-mixed using a two-roll mill. The melt-mixed mixture was then discharged through a twin-screw extruder, and sheet-like melt-mixed material was produced by passing it through calendering rolls located near the twin-screw extruder, and cooled at a rate of 1°C / min.

[0458] The flaky molten compound is micronized using a jet mill and further classified twice using a wind classifier to obtain colorant particles.

[0459] <Characteristics>

[0460] For each example of a colorant, the following properties were determined according to the method described above.

[0461] • Aspect ratio of crystalline resin microregions (denoted as aspect ratio AR in the table)

[0462] • The major axis length of the crystalline resin microregions (denoted as major axis length L in the table) Cry )

[0463] • The major axis length of the crystalline resin microregions (denoted as L in the table) Cry The ratio relative to the maximum diameter of the colorant particles

[0464] • The angle formed by the extension of the major axis of the crystalline resin micro-region and the tangent (the tangent being the tangent at the point where the extension intersects the surface of the colorant particle) (denoted as θ in the table). A )

[0465] • The angle between the extensions of the major axes of the two crystalline resin microregions (denoted as the angle θ in the table) B )

[0466] • The shortest distance between the micro-regions of the release agent present in the colorant particles and the surface (i.e., the outer edge) of the colorant particles (referred to in the table as the shortest distance between the micro-regions and the surface of the colorant particles).

[0467] • The proportion (number %) of the first colorant particle A relative to all colorant particles that meets the following conditions.

[0468] Condition (A): The aspect ratio of the crystalline resin microregions is 5 or higher and 40 or lower.

[0469] Condition (B1): The major axis length of the crystalline resin microregion is 0.5 μm or more and 1.5 μm or less.

[0470] Condition (C): The angle formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the colorant particles) is more than 60 degrees and less than 90 degrees.

[0471] Condition (D): The angle between the extensions of the major axes of the two crystalline resin microregions is more than 45 degrees and less than 90 degrees.

[0472] • Further satisfying the following condition (E): the proportion (number %) of the first colorant particle A relative to all colorant particles.

[0473] Condition (E): The micro-regions of the release agent exist at a depth of more than 50 nm inside the surface of the colorant particles.

[0474] • The proportion (number %) of the first colorant particle B relative to all colorant particles that meets the following conditions.

[0475] Condition (A'): The aspect ratio of the crystalline resin microregions is 10 or higher and 40 or lower.

[0476] Condition (B1'): The major axis length of the crystalline resin microregion is 0.8 μm or more and 1.5 μm or less.

[0477] Condition (C'): The angle formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the colorant particles) is more than 75 degrees and less than 90 degrees.

[0478] Condition (D'): The angle between the extensions of the major axes of the two crystalline resin microregions is more than 60 degrees and less than 90 degrees.

[0479] • Further satisfying the following condition (E): the proportion (number %) of the first colorant particle B relative to all colorant particles.

[0480] Condition (E): The micro-regions of the release agent exist at a depth of more than 50 nm inside the surface of the colorant particles.

[0481] • The proportion (number %) of second colorant particles A relative to all colorant particles that meet the following conditions.

[0482] Condition (A): The aspect ratio of the crystalline resin microregions is 5 or higher and 40 or lower.

[0483] Condition (B2): In at least one of the two crystalline resin microregions described above, the ratio of the long axis length to the maximum diameter of the colorant particles is more than 10% and less than 30%.

[0484] Condition (C): The angle formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the colorant particles) is more than 60 degrees and less than 90 degrees.

[0485] Condition (D): The angle between the extensions of the major axes of the two crystalline resin microregions is more than 45 degrees and less than 90 degrees.

[0486] • The proportion (number %) of the second colorant particles A relative to all colorant particles that further satisfy the following condition (E).

[0487] Condition (E): The micro-regions of the release agent exist at a depth of more than 50 nm inside the surface of the colorant particles.

[0488] • The proportion (number %) of second colorant particles B relative to all colorant particles that meet the following conditions.

[0489] Condition (A'): The aspect ratio of the crystalline resin microregions is 10 or higher and 40 or lower.

[0490] Condition (B2'): In at least one of the two crystalline resin microregions described above, the ratio of the long axis length to the maximum diameter of the colorant particles is more than 13% and less than 30%.

[0491] Condition (C'): The angle formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the colorant particles) is more than 75 degrees and less than 90 degrees.

[0492] Condition (D'): The angle between the extensions of the major axes of the two crystalline resin microregions is more than 60 degrees and less than 90 degrees.

[0493] • The proportion (number %) of the second colorant particles B relative to all colorant particles that further satisfy the following condition (E).

[0494] Condition (E): The micro-regions of the release agent exist at a depth of more than 50 nm inside the surface of the colorant particles.

[0495] It should be noted that the morphology of the crystalline resin microregions A and B of the representative colorant particles (hereinafter referred to as the representative colorant) and the microregions of the release agent are shown in Table 2. Details are as follows.

[0496] One hundred toner particles from each case were observed. Among the 100 toner particles observed, the toner particle with the largest angle (condition (C)) formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the junction where the extension meets the surface of the toner particle) was taken as the representative toner particle.

[0497] The crystalline resin micro-region with the largest angle (condition (C)) formed by the extension of the long axis of the crystalline resin micro-region and the tangent (the tangent is the tangent at the point where the extension meets the surface of the crystalline resin micro-region) in the representative toner particles is designated as crystalline resin micro-region A (refer to...). Figure 3 The morphology of the crystalline resin microregion A is shown in Table 2.

[0498] The crystalline resin microregion with the largest intersection angle (condition (D)) relative to the extension of the major axis of the representative toner particle of crystalline resin microregion A is designated as crystalline resin microregion B (refer to...). Figure 3 The morphology of the crystalline resin microregion B is shown in Table 2.

[0499] The intersection angle of the extended lines of the major axes of crystalline resin microregions A and B in representative colorant particles is shown in Table 2.

[0500] The morphology of the release agent micro-regions in representative colorant particles is shown in Table 2.

[0501] <Evaluation>

[0502] (Developing the developer)

[0503] Using the toning agents in each example, prepare the developer as follows.

[0504] Spherical magnetite powder particles (volume average particle size: 0.55 μm): 500 parts were thoroughly stirred using a Henschel mixer, and 5.0 parts of titanate coupling agent were added. The mixture was heated to 100°C and stirred for 30 minutes to obtain spherical magnetite particles coated with titanate coupling agent.

[0505] Next, 6.25 parts of phenol, 9.25 parts of 35% formaldehyde, 500 parts of the above-mentioned magnetite particles, 6.25 parts of 25% ammonia, and 425 parts of water were placed in a four-necked flask and mixed with stirring. Then, the mixture was reacted at 85°C for 120 minutes with stirring, cooled to 25°C, and 500 parts of water were added. The supernatant was removed, and the precipitate was washed with water. It was then dried under reduced pressure at a temperature between 150°C and 180°C to obtain a carrier with an average particle size of 35 μm.

[0506] Next, the toners from each example and the obtained carrier were added to a V-type mixer at a toner:carrier ratio of 5:95 (mass ratio) and stirred for 20 minutes to obtain the developer.

[0507] (Uneven gloss)

[0508] Using the obtained developer, the gloss unevenness was evaluated as follows.

[0509] The developer obtained in each embodiment and comparative example was filled into the developing chamber of the image forming apparatus "DocuCentrecolor 400, manufactured by Fuji Xerox Co., Ltd." Using this image forming apparatus, at an environment of 28°C and 85% RH, the (Japan) Electrophotographic Society Test Chart No. 5-1 was processed at a speed of 228 mm / s on OS coated paper (manufactured by Fuji Xerox InterField Co., Ltd., trade name: OS coated paper W 127 g / m²). 2 Output 1,000 solid images with 100% density (Toner loading (TMA) 10.0 g / m²). 2(Image). Subsequently, 1,000 solid images with a density of 100% were output on OS coated paper at a fixing temperature of 190℃ and a processing speed of 90m / s (toner loading (TMA) 14.4g / m). 2 (Image).

[0510] For the (Japan) Electrophotographic Society Test Chart No. 5-1 when outputting the 1001st OS coated paper sheet, and the (Japan) Electrophotographic Society Test Chart No. 5-1 after outputting 1500 and 2000 sheets, the gloss of the black parts was measured using the following method.

[0511] In the gloss measurement, a portable gloss meter (BYK Gardner Micro-Tri-Gloss, manufactured by Toyo Seiki Co., Ltd.) was used to measure the gloss at 60 degrees on 5 parts.

[0512] The difference is calculated from the measured gloss value and evaluated using the following evaluation criteria.

[0513] A: The gloss difference between the maximum and minimum gloss values ​​for 1,001, 1,500, and 2,000 output images is less than 3°.

[0514] B: The gloss difference between the maximum and minimum gloss values ​​for 1,001, 1,500, and 2,000 output images is less than 4°.

[0515] C: The gloss difference between the maximum and minimum gloss values ​​of the 1,001, 1,500, and 2,000 output images is less than 6°.

[0516] D: The gloss difference between the maximum and minimum gloss values ​​for 1,001, 1,500, and 2,000 output images is less than 8°.

[0517] E: The gloss difference between the maximum and minimum gloss values ​​of the 1,001, 1,500, and 2,000 output images is less than 10°.

[0518] F: The gloss difference between the maximum and minimum gloss values ​​for 1,001, 1,500, and 2,000 output images is greater than 10°.

[0519] [Table 1]

[0520]

[0521]

[0522] [Table 3]

[0523]

[0524] As can be seen from the above results, compared with the comparative example, this embodiment suppresses the degree of uneven gloss in the image when forming an image with a large amount of toner loading.

Claims

1. A toner for electrostatic image development, comprising toner particles containing both amorphous and crystalline resins. The content of the aforementioned colorant particles is more than 70% relative to all colorant particles. Furthermore, when observing the cross-section of the colorant particles, at least two of the aforementioned crystalline resin microregions satisfy the following conditions (A), (B1), (C), and (D). Condition (A): The aspect ratio of the above-mentioned crystalline resin microregions is 5 or more and 40 or less. Condition (B1): The major axis length of the above-mentioned crystalline resin microregions is 0.5 μm to 1.5 μm. Condition (C): The angle formed by the extension of the long axis of the above-mentioned crystalline resin micro-region and the tangent described below is 60 degrees or more and 90 degrees or less. This tangent is the tangent at the junction where the extension line meets the surface of the colorant particles. Condition (D): The angle between the extensions of the major axes of the two crystalline resin microregions mentioned above is more than 45 degrees and less than 90 degrees.

2. A toner for electrostatic image development, comprising toner particles containing both amorphous and crystalline resins. The content of the aforementioned colorant particles is more than 70% relative to all colorant particles. Furthermore, when observing the cross-section of the colorant particles, at least two of the aforementioned crystalline resin microregions satisfy the following conditions (A), (B2), (C), and (D). Condition (A): The aspect ratio of the above-mentioned crystalline resin microregions is 5 or more and 40 or less. Condition (B2): In at least one of the two aforementioned crystalline resin microregions, the ratio of the major axis length to the maximum diameter of the aforementioned colorant particles is 10% to 30%. Condition (C): The angle formed by the extension of the long axis of the above-mentioned crystalline resin micro-region and the tangent described below is 60 degrees or more and 90 degrees or less. This tangent is the tangent at the junction where the extension line meets the surface of the colorant particles. Condition (D): The angle between the extensions of the major axes of the two crystalline resin microregions mentioned above is more than 45 degrees and less than 90 degrees.

3. The toner for electrostatic image development as described in claim 1 or 2, wherein, The aforementioned colorant particles contain a release agent, and when the cross-section of the aforementioned colorant particles is observed, the micro-regions of the release agent exist within the interior at a depth of 50 nm or more from the surface of the aforementioned colorant particles.

4. The toner for electrostatic image development as described in claim 3, wherein, The release agent mentioned above is an ester-based wax.

5. The toner for electrostatic image development as described in claim 1 or 2, wherein, The content of the aforementioned colorant particles is more than 80% relative to all colorant particles.

6. An electrostatic image developer comprising the toner for electrostatic image development according to any one of claims 1 to 5.

7. A toner cartridge that is loaded and unloaded in an image forming apparatus, wherein the toner for electrostatic image development according to any one of claims 1 to 5 is stored.

8. A processing cartridge that is loaded and unloaded in an image forming apparatus, comprising a developing mechanism that stores the electrostatic image developer of claim 6, and using the electrostatic image developer to develop an electrostatic image formed on the surface of an image holder into a toner image.

9. An image forming apparatus comprising: Image holding volume; A charging mechanism that charges the surface of the image holder; An electrostatic image forming mechanism that forms an electrostatic image on the surface of the charged image holder; A developing mechanism that stores the electrostatic image developer of claim 6, and uses the electrostatic image developer to develop an electrostatic image formed on the surface of the image holder into a toner image. A transfer mechanism that transfers the toner image formed on the surface of the image holder to the surface of the recording medium; as well as A fixing mechanism fixes the toner image transferred to the surface of the recording medium.

10. An image forming method comprising the following steps: The charging step involves charging the surface of the image holder. The electrostatic image forming step involves forming an electrostatic image on the surface of the charged image holder. The developing step involves developing the electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer according to claim 6. The transfer step transfers the toner image formed on the surface of the image holder to the surface of the recording medium; as well as The fixing step involves fixing the toner image transferred to the surface of the recording medium.

Images