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

Abstract

To provide an electrostatic charge image development toner which suppresses image gloss unevenness that may occur when an image is formed on a thin recording medium at high speed through low-temperature fixing.SOLUTION: An electrostatic charge image development toner provided herein comprises toner particles containing an amorphous resin, a crystalline resin, and a mold release agent and satisfying the following condition (A1) and the following condition (B1) when a cross-section of a toner particle is observed. Condition (A1): one or more domains of the crystalline resin with a domain diameter corresponding to 10-40%, inclusive, of the maximum diameter of the toner particles are present. Condition (B1): one or more domains of the mold release agent with a domain diameter corresponding to 10-40%, inclusive, of the maximum diameter of the toner particles are present.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Methods for visualizing image information, such as the electrophotographic method, are currently used in various fields. In the electrophotographic method, an electrostatic latent image is formed as image information on the surface of an image carrier by charging and electrostatic charge image formation. Then, a toner image is formed on the surface of the image carrier by a developer containing toner, and after transferring this toner image to a recording medium, the toner image is fixed to the recording medium. Through these steps, the image information is visualized as an image.

[0002] For example, Patent Document 1 discloses "An electrostatic latent image developing toner containing toner base particles containing at least a binder resin containing an amorphous polyester resin and a crystalline resin, and a release agent, wherein the amorphous polyester resin is the main component of the binder resin, and the toner base particles contain a region (A) containing a structure in which the crystalline resin and the release agent are in contact, a region (B) containing a crystalline resin forming a filamentous crystal structure existing independently without contacting the release agent, and a region (C) containing a crystalline resin forming a lamellar crystal structure existing independently without contacting the release agent."

[0003] Also, Patent Document 2 discloses "A toner containing at least a binder resin, a crystalline polyester resin, a colorant, and a release agent, wherein the volume average particle diameter of the toner is in the range of 4 to 8 μm, a release agent domain exists in a toner cross-sectional image in which the equivalent circle diameter of the toner cross-section is in the range of 4 to 8 μm, and when the ratio (distance A / equivalent circle diameter) of the distance A between the center of gravity of the release agent domain and the center of gravity of the toner cross-section to the equivalent circle diameter of the toner cross-section is divided into regions at intervals of 0.05 from 0, the number frequency of the release agent domain is the highest in the region where the ratio (distance A / equivalent circle diameter) is 0.25 or more and 0.3 or less, and the toner in which the number frequency of the release agent domain in the region where the ratio (distance A / equivalent circle diameter) is 0.25 or more and 0.3 or less is 20% or more."

[0004] Further, Patent Document 3 proposes "a toner containing toner particles containing a binder resin and a wax, and organosilicon polymer particles, wherein the wax is an ester wax, the average major axis of the domain of the wax is 0.03 μm or more and 2.00 μm or less, and the SP value SPw of the wax is 8.59 or more and 9.01 or less."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem of the present invention is that, compared with an electrostatic charge image developing toner having only toner particles that do not satisfy the following condition (A1) and the following condition (B1) when observing the cross-section of the toner particles, which contains an amorphous resin, a crystalline resin, and a release agent, to suppress the gloss difference between the first and tenth images that occurs when forming an image on a thin recording medium with high-speed and low-temperature fixing. That is to provide an electrostatic charge image developing toner.

Means for Solving the Problems

[0007] The means for solving the above problems include the following aspects. <1> An electrostatic charge image developing toner containing an amorphous resin, a crystalline resin, and a release agent, having toner particles that satisfy the following condition (A1) and the following condition (B1) when observing the cross-section of the toner particles. Condition (A1): There is one or more domains of the crystalline resin in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. Condition (B1): There is one or more domains of the mold release agent in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. <2> The electrostatic charge image developing toner according to <1>, wherein when the cross section of the toner particles is observed, the toner particles satisfy the following condition (A2) and the following condition (B2). Condition (A2): There are a plurality of domains of the crystalline resin in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. Condition (B2): There are a plurality of domains of the mold release agent in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. <3> The electrostatic charge image developing toner according to <1> or <2>, wherein when the cross section of the toner particles is observed, the toner particles satisfy the following condition (C1). Condition (C1): The domain of the crystalline resin is needle-shaped or plate-shaped, and the domain of the mold release agent is circular. <4> The electrostatic charge image developing toner according to <1> or <2>, wherein when the cross section of the toner particles is observed, the toner particles satisfy the following condition (C2). Condition (C2): The domain of the crystalline resin is circular, and the domain of the mold release agent is needle-shaped or plate-shaped. <5> The electrostatic charge image developing toner according to <3> or <4>, wherein the aspect ratio of the needle-shaped or plate-shaped domain is 5 or more and 40 or less, and the circularity of the circular domain is 0.92 or more and 1.00. <6> The electrostatic charge image developing toner according to any one of <1> to <5>, wherein the melting temperature of the mold release agent is 65°C or higher and 95°C or lower. <7> The electrostatic charge image developing toner according to <6>, wherein the mold release agent having a melting temperature of 65°C or higher and 95°C or lower is an ester wax. <8> The electrostatic charge image developing toner according to any one of <1> to <7>, wherein the content of the toner particles is 30% by number or more based on all the toner particles. <9> The electrostatic charge image developing toner according to <8>, wherein the content of the toner particles is 70% by number or more based on all the toner particles. An electrostatic charge image developing agent containing the toner for electrostatic charge image development according to any one of <1> to <9>. <11> Accommodating the toner for electrostatic charge image development according to any one of <1> to <9>, A toner cartridge detachable from an image forming apparatus. <12> An image forming apparatus including a developing unit that accommodates the electrostatic charge image developing agent according to <10> and develops an electrostatic charge image formed on the surface of an image carrier as a toner image by using the electrostatic charge image developing agent, A process cartridge detachable from an image forming apparatus. <13> An image carrier, A charging unit that charges the surface of the image carrier, An electrostatic charge image forming unit that forms an electrostatic charge image on the charged surface of the image carrier, <10> A developing unit that accommodates the electrostatic charge image developing agent according to <10> and develops an electrostatic charge image formed on the surface of the image carrier as a toner image by using the electrostatic charge image developing agent, A transfer unit that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium, A fixing unit that fixes the toner image transferred to the surface of the recording medium, An image forming apparatus including the above components. <14> A charging step of charging the surface of an image carrier, An electrostatic charge image forming step of forming an electrostatic charge image on the charged surface of the image carrier, <10> A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image by using the electrostatic charge image developing agent according to <10>, A transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, A fixing step of fixing the toner image transferred to the surface of the recording medium, An image forming method including the above steps.

Advantages of the Invention

[0008] According to the invention according to <1>, compared with an electrostatic charge image developing toner having only toner particles that do not satisfy the above conditions (A1) and (B1) when observing the cross section of the toner particles, which contains an amorphous resin, a crystalline resin, and a release agent, there is provided an electrostatic charge image developing toner that suppresses uneven gloss of an image when forming an image on a thin recording medium at high speed and low temperature. According to the invention according to <2>, compared with an electrostatic charge image developing toner having only toner particles that satisfy the above conditions (A1) and (B1) but do not satisfy the above conditions (A2) and (B2), there is provided an electrostatic charge image developing toner that suppresses the gloss difference between the first and tenth images when forming an image on a thin recording medium at high speed and low temperature.

[0009] According to the invention according to <3> or <4>, compared with an electrostatic charge image developing toner having only toner particles that satisfy the above conditions (A1) and (B1) or conditions (A2) and (B2), but satisfy the condition (D) "both the domain of the crystalline resin and the domain of the release agent are needle-shaped or plate-shaped, or both are circular", there is provided an electrostatic charge image developing toner that suppresses the gloss difference between the first and tenth images when forming an image on a thin recording medium at high speed and low temperature. According to the invention according to <5>, compared with the case where the aspect ratio of the needle-shaped or plate-shaped domain is less than 5, or the circularity of the circular domain is less than 0.92, there is provided an electrostatic charge image developing toner that suppresses the gloss difference between the first and tenth images when forming an image on a thin recording medium at high speed and low temperature.

[0010] According to the invention according to <6>, compared with the case where the melting temperature of the release agent exceeds 95°C, there is provided an electrostatic charge image developing toner that suppresses the gloss difference between the first and tenth images when forming an image on a thin recording medium at high speed and low temperature. According to the invention according to <7>, compared with the case where the release agent having a melting temperature of 65°C or higher and 95°C or lower is a release agent other than an ester wax, there is provided an electrostatic charge image developing toner that suppresses the gloss difference between the first and tenth images when forming an image on a thin recording medium at high speed and low temperature.

[0011] According to the invention according to <8> or <9>, when the content of toner particles satisfying the above condition (A1) and condition (B1) or condition (A2) and condition (B2) is less than 30% by number or less than 70% by number, compared with the case where an image is formed on a thin recording medium by high-speed and low-temperature fixing, there is provided an electrostatic charge image developing toner that suppresses the gloss difference between the first and tenth images generated.

[0012] According to the invention according to <10>, <11>, <12>, <13> or <14>, including an amorphous resin, a crystalline resin, and a release agent, when observing the cross-section of toner particles, compared with the case of applying to an electrostatic charge image developing toner having only toner particles that do not satisfy the above condition (A1) and condition (B1), there is provided an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method that suppresses the gloss difference between the first and tenth images generated when an image is formed on a thin recording medium by high-speed and low-temperature fixing.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments which are examples of the present invention will be described in detail. In the numerical ranges described step by step, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical range, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. When there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, the amount of each component in the composition means the total amount of the plurality of substances present in the composition. The term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step is achieved.

[0015] <Electrostatic charge image developing toner> The electrostatic charge image developing toner according to this embodiment (hereinafter referred to as "toner") contains an amorphous resin, a crystalline resin, and a release agent, and has toner particles that satisfy the following conditions (A1) and (B1) when observing the cross-section of the toner particles. Condition (A1): There is one or more domains of the crystalline resin in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. Condition (B1): There is one or more domains of the release agent in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less.

[0016] Due to the above configuration, the toner according to this embodiment suppresses the gloss difference between the first and tenth images that occurs when forming an image on a thin recording medium with high-speed and low-temperature fixing. The reason is speculated as follows.

[0017] When forming a solid image of TMA 4.0 g / m up to 5 mm from the leading edge of the paper on a thin recording medium (for example, paper with a basis weight of 60 g / m 2 of the following paper) and forming a fixed image at high speed (for example, a high speed of 300 mm / sec or more for the conveyance speed of the recording medium) and low-temperature fixing (for example, low-temperature fixing at a fixing temperature of 150°C or less), uneven gloss of the image may occur. 2 When forming a solid image of TMA 4.0 g / m up to 5 mm from the leading edge of the paper on a thin recording medium (for example, paper with a basis weight of 60 g / m This is because, in the case of high-speed and low-temperature fixing, it is difficult for heat to be transferred to the toner during fixing, making it difficult for the toner to melt sufficiently. Also, it becomes difficult for the release agent to bleed out, resulting in low releasability with respect to the fixing member. In particular, when performing high-speed and low-temperature fixing on a thin recording medium, since the heat of the fixing roll is not sufficiently heated, heat is not sufficiently transferred to the first sheet of the recording medium, making it difficult for the release agent to bleed out and causing the recording medium to easily wrap around the fixing member. On the other hand, after the tenth sheet, since the heat of the fixing member warms up, heat is transferred to the paper, and the bleed-out property of the release agent becomes good. As a result, the way heat is transferred is different between the first sheet and the tenth sheet, and since the meltability of the toner is also different, an image gloss difference is likely to occur.

[0018] Therefore, in the toner according to this embodiment, toner particles that satisfy condition (A1) and condition (B1) are employed. Condition (A1) indicates that a domain of a large crystalline resin is present in the toner particles. When a domain of a large crystalline resin is present in the toner particles, the meltability of the toner particles during fixing is enhanced. Condition (B1) indicates that a domain of a large release agent is present in the toner particles. When a domain of a large release agent is present in the toner particles, the bleed-out property of the release agent from the toner particles during fixing is enhanced.

[0019] That is, toner particles that satisfy condition (A1) and the following condition (B1) have both a domain of a large crystalline resin and a domain of a large release agent present therein (see FIG. 3). During fixing, both the meltability of the toner particles and the bleed-out property of the release agent from the toner particles are enhanced. Thereby, even when forming an image for high-speed and low-temperature fixing on a thin recording medium, the toner particles melt sufficiently during fixing, and the release agent easily bleeds out, and the releasability with respect to the fixing member also increases. As a result, unevenness in image gloss is suppressed. In particular, when the domain of the crystalline resin in the toner particles is large, it quickly dissolves to the inside of the toner particles, making it easier for the entire toner to melt. As a result, the release agent with a large diameter also melts and easily bleeds out from the toner particles. As a result, the toner melts sufficiently and the release agent easily bleeds out on the first sheet where the fixing member is not sufficiently warmed up. As a result, an image gloss difference between the first sheet and the tenth sheet is less likely to occur.

[0020] From the above, it is presumed that the toner according to the present embodiment suppresses the gloss difference between the first and tenth images that occurs when forming an image on a thin recording medium with high-speed and low-temperature fixing.

[0021] Note that the crystalline resin and the release agent are the same crystalline component, and during the granulation of toner particles, it is easy to form domains near each other, and if both are made larger, the probability of contact between their domains increases. Therefore, in the prior art, it has been difficult to manufacture toner particles in which both a large domain of the crystalline resin and a large domain of the release agent exist.

[0022] Here, each reference sign shown in FIG. 3 is TN: Toner particle Amo: Amorphous resin Cry: Crystalline resin L T : Maximum diameter of toner particle L cry : Maximum diameter of crystalline resin Lw: Maximum diameter of toner particle

[0023] Hereinafter, the toner according to the present embodiment will be described in detail.

[0024] The toner according to the present embodiment has toner particles. The toner may have an external additive.

[0025] (Toner particle) The toner particles contain an amorphous resin and a crystalline resin as binder resins. Note that the toner particles may contain a colorant, a release agent, and other additives.

[0026] -(Morphology of domains of crystalline resin and release agent in toner particles)- When observing the cross section of the toner particles, the domains of the crystalline resin and the release agent satisfy conditions (A1) and (B1). From the viewpoint of suppressing the gloss difference between the first and tenth images, it is preferable that the domains of the crystalline resin and the release agent satisfy conditions (A2) and (B2). From the viewpoint of suppressing the gloss difference between the first and tenth images, it is further preferable that the domains of the crystalline resin and the release agent satisfy condition (C1) or (C2).

[0027] Here, toner particles satisfying condition (A1) and condition (B1), or condition (A2) and condition (B2) are preferably 30% or more, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more, based on all the toner particles, from the viewpoint of suppressing the gloss difference between the first and tenth images. Ideally, the proportion of toner particles satisfying each of the above conditions is 100%. The more toner particles satisfy each of the above conditions, the easier it is to suppress the gloss difference between the first and tenth images.

[0028] In addition to condition (A1) and condition (B1), or condition (A2) and condition (B2), the proportion of toner particles satisfying condition (C1) or condition (C2) described later is also preferably 30% or more, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more, based on all the toner particles, from the viewpoint of suppressing the gloss difference between the first and tenth images. Ideally, the proportion of toner particles satisfying each of the above conditions is 100%.

[0029] · Condition (A1) and the following condition (B1) Condition (A1): There is one or more domains of the crystalline resin in which the domain diameter with respect to the maximum diameter of the toner particle is 10% or more and 40% or less. Condition (B1): There is one or more domains of the release agent in which the domain diameter with respect to the maximum diameter of the toner particle is 10% or more and 40% or less.

[0030] · Condition (A2) and condition (B2) Condition (A2): There are a plurality of domains of the crystalline resin in which the domain diameter is 10% or more and 40% or less with respect to the maximum diameter of the toner particles. Condition (B2): There are a plurality of domains of the mold release agent in which the domain diameter is 10% or more and 40% or less with respect to the maximum diameter of the toner particles.

[0031] Here, specifically, the domain diameter of the crystalline resin is, for example, 0.5 μm or more and 2.0 μm or less. Specifically, the domain diameter of the mold release agent is, for example, 0.5 μm or more and 2.0 μm or less. The domain diameters of the crystalline resin and the mold release agent mean the maximum diameters of the domains of the crystalline resin and the mold release agent (that is, the maximum length of a straight line drawn between any two points on the contour line of the cross-section of the crystalline resin and the mold release agent). The maximum diameter of the toner particles means the maximum length of a straight line drawn between any two points on the contour line of the cross-section of the toner particles.

[0032] · Condition (C1) The domain of the crystalline resin is needle-shaped or plate-shaped, and the domain of the mold release agent is circular. · Condition (C2) The domain of the crystalline resin is circular, and the domain of the mold release agent is needle-shaped or plate-shaped.

[0033] When one of the domains of the crystalline resin and the mold release agent is needle-shaped or plate-shaped and the other is circular, the domains of both are likely to increase in size, and the gloss difference between the first and tenth images is likely to be suppressed. In particular, when the domain of the crystalline resin is large and needle-shaped or plate-shaped, the toner particles are likely to melt to the inside during fixing. The exudability of the mold release agent is enhanced by the large and circular domain of the mold release agent. Therefore, when condition (C1) is satisfied, the gloss difference between the first and tenth images is more likely to be suppressed. On the other hand, when the domain of the crystalline resin is large-diameter and circular, and the domain of the release agent is large-diameter and needle-shaped or plate-shaped, the crystalline resin in the toner particles melts during fixing, and the toner particles are likely to be crushed. At this time, when the domain of the release agent is large-diameter and needle-shaped or plate-shaped, the release agent is likely to ooze out in the major axis direction from the crushed toner particles, so it becomes easier to satisfy the condition (C2) and the gloss difference between the first and tenth images is likely to be suppressed.

[0034] Here, the aspect ratio of the needle-shaped or plate-shaped domain (particularly, the aspect ratio of the domain of the crystalline resin) is preferably 5 or more and 40 or less, more preferably 15 or more and 40 or less, from the viewpoint of suppressing the gloss difference between the first and tenth images. The aspect ratio of the needle-shaped or plate-shaped domain means the ratio (major axis length / minor axis length) of the major axis length (that is, the maximum diameter) and the minor axis length in the domain. The major axis length of the needle-shaped or plate-shaped domain means the maximum diameter of the needle-shaped or plate-shaped domain (that is, the maximum length of a straight line drawn between any two points on the contour line of the cross-section of the domain). The minor axis length of the needle-shaped or plate-shaped domain means the maximum length among the lengths in the direction orthogonal to the extension line of the major axis length of the domain.

[0035] The circularity of the circular domain (particularly, the circularity of the domain of the release agent) is preferably 0.92 or more and 1.00, more preferably 0.95 or more and 1.00 or less, from the viewpoint of suppressing the gloss difference between the first and tenth images. The circularity of the domain is the circularity defined by the following formula. Formula: Circularity (100 / SF2) = 4π × (A / I 2 ) Formula (1) In Formula (1), I represents the perimeter of the domain, and A represents the area of the domain.

[0036] · Observation method of the cross-section of toner particles The observation method of the cross-section of toner particles for determining whether the toner particles satisfy each condition is as follows. Mix toner particles (or toner particles with an external additive attached) with an epoxy resin and embed them, then solidify the epoxy resin. Cut the obtained solidified product with an ultramicrotome (Leica Ultracut UCT) to prepare a thin sample with a thickness of 80 nm or more and 130 nm or less. Next, stain the obtained thin sample with ruthenium tetroxide in a desiccator at 30 °C for 3 hours. Then, obtain a STEM observation image in the transmission image mode (acceleration voltage: 30 kV, magnification: 20,000 times) of the stained thin sample with a high-resolution field emission scanning electron microscope (FE-SEM, Hitachi High-Technologies S-4800). In the toner particles, determine the crystalline polyester resin and the release agent from the contrast and shape. In the SEM image, the ruthenium-stained crystalline resin has more double bond parts than the amorphous resin, release agent, etc., and is stained by ruthenium tetroxide, so the release agent part and the resin part other than the release agent can be distinguished. That is, by ruthenium staining, it is the domain where the release agent is stained the thinnest, and then the crystalline resin (for example, crystalline polyester resin) is stained, and the amorphous resin (for example, amorphous polyester resin) is stained the darkest. By adjusting the contrast, the release agent can be judged as a domain observed as white, the amorphous resin as black, and the crystalline resin as light gray.

[0037] Then, image-analyze the region of the ruthenium-stained crystalline resin to judge whether the toner particles meet each condition. Also, when obtaining the ratio of toner particles that meet each of the above conditions, observe 100 toner particles and calculate the ratio of toner particles that meet each of the above conditions.

[0038] Note that since the SEM image contains toner particle cross-sections of various sizes, select a toner particle cross-section whose diameter is 85% or more of the volume average particle diameter of the toner particles as the toner particles to be observed. Here, the diameter of the toner particle cross-section refers to the maximum length of a straight line drawn between any two points on the contour line of the toner particle cross-section (so-called major axis).

[0039] -Binder resin- Examples of the binder resin include vinyl resins composed of homopolymers of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (e.g., ethylene, propylene, butadiene, etc.), or copolymers obtained by combining two or more of these monomers. Examples of the binder resin also include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, modified rosin, mixtures of these and the vinyl resins, or graft polymers obtained by polymerizing vinyl monomers in the coexistence of these. These binder resins may be used alone or in combination of two or more.

[0040] In particular, it is preferable to apply an amorphous resin and a crystalline resin as the binder resin. However, the mass ratio of the crystalline resin to the amorphous 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.

[0041] Here, the amorphous resin refers to a material that has only a stepwise endothermic change rather than a distinct endothermic peak in thermal analysis measurement using differential scanning calorimetry (DSC), is a solid at room temperature, and is thermoplastified at a temperature above the glass transition temperature. On the one hand, a crystalline resin refers to a resin that has a distinct endothermic peak rather than a step-like change in the endothermic quantity in differential scanning calorimetry (DSC). Specifically, for example, a crystalline resin means that the half-width of the endothermic peak measured at a heating rate of 10 °C / min is within 10 °C, and an amorphous resin means a resin with a half-width exceeding 10 °C or a resin for which no distinct endothermic peak is observed.

[0042] An amorphous resin will be described. Examples of amorphous resins include known amorphous resins such as amorphous polyester resins, amorphous vinyl resins (e.g., styrene-acrylic resins, etc.), 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. In addition, it is also a preferred embodiment to use an amorphous polyester resin and a styrene-acrylic resin in combination as the amorphous resin. Further, it is also a preferred embodiment to apply an amorphous resin having an amorphous polyester resin segment and a styrene-acrylic resin segment as the amorphous resin.

[0043] · Amorphous polyester resin Examples of amorphous polyester resins include condensation polymers of polyvalent carboxylic acids and polyhydric alcohols. As the amorphous polyester resin, commercially available products may be used, or synthesized products may be used.

[0044] Examples of polyvalent carboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), anhydrides thereof, or lower (e.g., having 1 to 5 carbon atoms) alkyl esters thereof. Among these, aromatic dicarboxylic acids are preferred as the polyvalent carboxylic acid. The polyvalent carboxylic acid may be used in combination with a carboxylic acid having a trivalent or higher valence that forms a crosslinked structure or a branched structure together with the dicarboxylic acid. Examples of the carboxylic acid having a trivalent or higher valence include trimellitic acid, pyromellitic acid, their anhydrides, or their lower (e.g., having 1 to 5 carbon atoms) alkyl esters. The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0045] Examples of the polyhydric alcohol include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, etc.). Among these, as the polyhydric alcohol, aromatic diols and alicyclic diols are preferred, and aromatic diols are more preferred. The polyhydric alcohol may be used in combination with a polyhydric alcohol having a trivalent or higher valence that forms a crosslinked structure or a branched structure together with the diol. Examples of the polyhydric alcohol having a trivalent or higher valence include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohol may be used alone or in combination of two or more.

[0046] The amorphous polyester resin is obtained by a known production method. Specifically, for example, it is obtained by a method in which the polymerization temperature is set to 180°C or higher and 230°C or lower, the inside of the reaction system is depressurized as necessary, and the reaction is carried out while removing water or alcohol generated during condensation. When the monomer of the raw material is not soluble or compatible at the reaction temperature, a high-boiling solvent may be added as a dissolution aid to dissolve it. In this case, the polycondensation reaction is carried out while distilling off the dissolution aid. When there is a monomer with poor compatibility in the copolymerization reaction, it is advisable to first condense the monomer with poor compatibility with the acid or alcohol intended for polycondensation and then carry out polycondensation with the main component.

[0047] Examples of the amorphous polyester resin include not only the unmodified amorphous polyester resin but also the modified amorphous polyester resin. The modified amorphous polyester resin is an amorphous polyester resin having a bonding group other than an ester bond or an amorphous polyester resin in which a resin component different from polyester is bonded by a covalent bond, an ionic bond, or the like. Examples of the modified amorphous polyester resin include a resin obtained by reacting an amorphous polyester resin having a functional group such as an isocyanate group introduced at the terminal with an active hydrogen compound to modify the terminal.

[0048] The proportion of the amorphous polyester resin in the total binder resin is preferably 60% by mass or more and 98% by mass or less, more preferably 65% by mass or more and 95% by mass or less, and still more preferably 70% by mass or more and 90% by mass or less.

[0049] · Styrene acrylic resin The styrene acrylic resin is a copolymer obtained by copolymerizing at least a styrene monomer (a monomer having a styrene skeleton) and a (meth)acrylic monomer (a monomer having a (meth)acrylic group, preferably a monomer having a (meth)acryloxy group). The styrene acrylic resin includes, for example, a copolymer of a styrene monomer and a (meth)acrylate monomer. Note that the acrylic resin portion in the styrene acrylic resin is a partial structure formed by polymerizing either an acrylic monomer or a methacrylic monomer, or both. The expression “(meth)acrylic” includes both “acrylic” and “methacrylic”.

[0050] Examples of the styrene monomer include styrene, α-methylstyrene, metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, meta-tert-butoxystyrene, para-tert-butoxystyrene, parabenzene vinyl benzoic acid, paramethyl-α-methylstyrene, and the like. The styrene monomer may be used alone or in combination of two or more.

[0051] Examples of the (meth)acrylic monomer include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. The (meth)acrylic monomer may be used alone or in combination of two or more.

[0052] The polymerization ratio of the styrene monomer to the (meth)acrylic monomer is preferably 70:30 to 95:5 on a mass basis, i.e., styrene monomer:(meth)acrylic monomer.

[0053] The styrene acrylic resin may have a crosslinked structure. The styrene acrylic resin having a crosslinked structure can be produced, for example, by copolymerizing a styrene monomer, a (meth)acrylic monomer, and a crosslinkable monomer. The crosslinkable monomer is not particularly limited, but a bifunctional or higher (meth)acrylate compound is preferred.

[0054] The method for producing the styrene acrylic resin is not particularly limited, and for example, solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization are applicable. Known operations (for example, batchwise, semi-continuous, continuous, etc.) are applicable to the polymerization reaction.

[0055] The proportion of the styrene acrylic resin in the total binder resin is preferably 0% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and still more preferably 2% by mass or more and 10% by mass or less.

[0056] · An amorphous resin having an amorphous polyester resin segment and a styrene acrylic resin segment (hereinafter also referred to as "hybrid amorphous resin") The hybrid amorphous resin is an amorphous resin in which an amorphous polyester resin segment and a styrene acrylic resin segment are chemically bonded. The hybrid amorphous resin includes: a resin having a main chain made of a polyester resin and a side chain made of a styrene acrylic resin chemically bonded to the main chain; a resin having a main chain made of a styrene acrylic resin and a side chain made of a polyester resin chemically bonded to the main chain; a resin having a main chain formed by chemical bonding of a polyester resin and a styrene acrylic resin; a resin having a main chain formed by chemical bonding of a polyester resin and a styrene acrylic resin, and at least one of a side chain made of a polyester resin chemically bonded to the main chain and a side chain made of a styrene acrylic resin chemically bonded to the main chain; etc.

[0057] The amorphous polyester resin and the styrene acrylic resin of each segment are as described above, and the description is omitted.

[0058] The total amount of the polyester resin segment and the styrene acrylic resin segment in the hybrid amorphous resin is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably 100% by mass.

[0059] In the hybrid amorphous resin, the proportion of the styrene acrylic resin segment in the total amount of the polyester resin segment and the styrene acrylic resin segment is preferably 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 55% by mass or less, and still more preferably 30% by mass or more and 50% by mass or less.

[0060] The hybrid amorphous resin is preferably produced by any one of the following methods (i) to (iii). (i) After producing a polyester resin segment by polycondensation of a polyhydric alcohol and a polycarboxylic acid, monomers constituting a styrene acrylic resin segment are addition-polymerized. (ii) After producing a styrene acrylic resin segment by addition polymerization of an addition-polymerizable monomer, a polyhydric alcohol and a polycarboxylic acid are polycondensed. (iii) Polycondensation of a polyhydric alcohol and a polycarboxylic acid and addition polymerization of an addition-polymerizable monomer are carried out in parallel.

[0061] The proportion of the hybrid amorphous resin in all the binder resins is preferably 60% by mass or more and 98% by mass or less, more preferably 65% by mass or more and 95% by mass or less, and still more preferably 70% by mass or more and 90% by mass or less.

[0062] The properties of the amorphous resin will be described. The glass transition temperature (Tg) of the amorphous resin is preferably 50°C or more and 80°C or less, and more preferably 50°C or more and 65°C or less. The glass transition temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC). More specifically, it is determined by the "extrapolated onset temperature of glass transition" described in the method for determining the glass transition temperature in JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics".

[0063] The weight average molecular weight (Mw) of the amorphous resin is preferably 5000 or more and 1000000 or less, and more preferably 7000 or more and 500000 or less. The number average molecular weight (Mn) of the amorphous resin is preferably 2000 or more and 100000 or less. The molecular weight distribution Mw / Mn of the amorphous resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less. The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed using Tosoh's GPC·HLC-8120GPC as the measurement device, Tosoh's column·TSKgel SuperHM-M (15 cm), and THF solvent. The weight average molecular weight and the number average molecular weight are calculated using the molecular weight calibration curve prepared from the measurement results with a monodisperse polystyrene standard sample.

[0064] The crystalline resin will be described. Examples of the crystalline resin include known crystalline resins such as crystalline polyester resins and crystalline vinyl resins (for example, polyalkylene resins, long-chain alkyl (meth)acrylate resins, etc.). Among these, crystalline polyester resins are preferred from the viewpoints of the mechanical strength and low-temperature fixability of the toner.

[0065] ·Crystalline polyester resin Examples of the crystalline polyester resin include polycondensates of polyvalent carboxylic acids and polyhydric alcohols. As the crystalline polyester resin, commercially available products may be used, or synthesized ones may be used. Since the crystalline polyester resin easily forms a crystal structure, a polycondensate using a linear aliphatic polymerizable monomer rather than an aromatic-ring-containing polymerizable monomer is preferred.

[0066] Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (for example, oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (for example, dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, etc.), anhydrides thereof, or lower (for example, having 1 to 5 carbon atoms) alkyl esters thereof. The polyvalent carboxylic acid may be used in combination with a carboxylic acid having a trivalent or higher valence that forms a crosslinked structure or a branched structure together with the dicarboxylic acid. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), anhydrides thereof, or lower (e.g., having 1 to 5 carbon atoms) alkyl esters thereof. As the polyvalent carboxylic acid, a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids. The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0067] Examples of the polyhydric alcohol include aliphatic diols (e.g., linear aliphatic diols having 7 to 20 carbon atoms in the main chain portion). Examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,14-eicosandecanediol, etc. Among these, as the aliphatic diol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable. The polyhydric alcohol may be used in combination with an alcohol having a trivalent or higher valence that forms a crosslinked structure or a branched structure together with the diol. Examples of the alcohol having a trivalent or higher valence include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc. The polyhydric alcohol may be used alone or in combination of two or more.

[0068] The content of the aliphatic diol in the polyhydric alcohol is preferably 80 mol% or more, more preferably 90 mol% or more.

[0069] The crystalline polyester resin can be obtained by a known production method, for example, in the same manner as the amorphous polyester resin.

[0070] As the crystalline polyester resin, a polymer of an α,ω-linear aliphatic dicarboxylic acid and an α,ω-linear aliphatic diol is preferable. Since the polymer of an α,ω-linear aliphatic dicarboxylic acid and an α,ω-linear aliphatic diol has high compatibility with the amorphous polyester resin, it is easier to suppress the gloss difference between the first and tenth images.

[0071] As the α,ω-linear aliphatic dicarboxylic acid, an α,ω-linear aliphatic dicarboxylic acid in which the number of carbon atoms of the alkylene group connecting two carboxy groups is 3 or more and 14 or less is preferable, the number of carbon atoms of the alkylene group is more preferably 4 or more and 12 or less, and the number of carbon atoms of the alkylene group is even more preferably 6 or more and 10 or less. Examples of the α,ω-linear aliphatic dicarboxylic acid include succinic acid, glutaric acid, adipic acid, 1,6-hexanedicarboxylic acid (common name suberic acid), 1,7-heptanedicarboxylic acid (common name azelaic acid), 1,8-octanedicarboxylic acid (common name sebacic acid), 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc. Among them, 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid are preferable. The α,ω-linear aliphatic dicarboxylic acid may be used alone or in combination of two or more.

[0072] As the α,ω-linear aliphatic diol, an α,ω-linear aliphatic diol in which the number of carbon atoms of the alkylene group connecting two hydroxy groups is 3 or more and 14 or less is preferable, the number of carbon atoms of the alkylene group is more preferably 4 or more and 12 or less, and the number of carbon atoms of the alkylene group is even more preferably 6 or more and 10 or less. Examples of the α,ω-linear aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, etc. Among them, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred. The α,ω-linear aliphatic diol may be used alone or in combination of two or more.

[0073] From the viewpoint of suppressing the gloss difference between the first and tenth images, the polymer of the α,ω-linear aliphatic dicarboxylic acid and the α,ω-linear aliphatic diol is preferably a polymer of at least one selected from the group consisting of 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid and at least one selected from the group consisting of 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol. Among them, the polymer of 1,10-decanedicarboxylic acid and 1,6-hexanediol is more preferred.

[0074] The proportion of the crystalline polyester resin in all the binder resins is preferably 1% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 15% by mass or less, and still more preferably 3% by mass or more and 10% by mass or less. The properties of the crystalline resin will be described. The melting temperature of the crystalline resin is preferably 50°C or more and 100°C or less, more preferably 55°C or more and 90°C or less, and still more preferably 60°C or more and 85°C or less. The melting temperature is determined by the "melting peak temperature" described in the method for determining the melting temperature of JIS K7121-1987 "Method for Measuring the Transition Temperature of Plastics" from the DSC curve obtained by differential scanning calorimetry (DSC).

[0075] The weight average molecular weight (Mw) of the crystalline resin is preferably 6,000 or more and 35,000 or less.

[0076] The content of the binder resin is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and still more preferably 60% by mass or more and 85% by mass or less with respect to the total toner particles.

[0077] - Colorant - Examples of the colorant include pigments such as carbon black, chrome yellow, Hansa yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watchung red, permanent red, brilliant carmine 3B, brilliant carmine 6B, duPont oil red, pyrazolone red, resorcin red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, malachite green oxalate; dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, aniline black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, thiazole-based dyes. The colorant may be used alone or in combination of two or more.

[0078] The colorant may be a surface-treated colorant used as necessary, or may be used in combination with a dispersant. Also, a plurality of types of colorants may be used in combination.

[0079] The content of the colorant is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 15% by mass or less, based on the total toner particles.

[0080] -Release agent- Examples of the release agent include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, candelilla wax, etc.; synthetic or mineral / petroleum waxes such as montan wax; ester waxes such as fatty acid esters, montanic acid esters, etc. The release agent is not limited thereto.

[0081] The melting temperature of the release agent is preferably 50°C or more and 110°C or less, more preferably 60°C or more and 100°C or less. The melting temperature of the release agent is determined by the "melting peak temperature" described in the method for obtaining the melting temperature in JIS K7121:1987 "Method for Measuring the Transition Temperature of Plastics" from the DSC curve obtained by differential scanning calorimetry (DSC).

[0082] In particular, the melting temperature of the release agent is preferably 65°C or more and 95°C or less, more preferably 67°C or more and 91°C or more. When a release agent with a melting temperature of 65°C or more and 95°C or less is applied, the release agent is likely to increase in diameter and become spherical, and the toner particles are likely to satisfy the above conditions (B1), (B2), and (C1).

[0083] Also, as the release agent with a melting temperature of 65°C or more and 95°C or less, an ester wax is preferable. The ester wax also makes it easier for the release agent to increase in diameter and become spherical, and the toner particles are likely to satisfy the above conditions (B1), (B2), and (C1).

[0084] Furthermore, when using a paraffin wax (especially an ethylene wax) as the release agent with a melting temperature of 65°C or more and 95°C or less, the domain of the release agent is likely to increase in diameter and become needle-like or plate-like, and the toner particles are likely to satisfy the above condition (C2).

[0085] Ester waxes are waxes having an ester bond. As the ester waxes, any of monoester, diester, triester, and tetraester may be used, and known natural or synthetic ester waxes can be adopted. Examples of the ester waxes include ester compounds of higher fatty acids (such as fatty acids having 10 or more carbon atoms) and monohydric or polyhydric aliphatic alcohols (such as aliphatic alcohols having 8 or more carbon atoms). Examples of the ester waxes include ester compounds of higher fatty acids (such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, etc.) and alcohols (monohydric alcohols such as methanol, ethanol, propanol, isopropanol, butanol, capryl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, etc.; polyhydric alcohols such as glycerin, ethylene glycol, propylene glycol, sorbitol, pentaerythritol, etc.). Specifically, carnauba wax, rice wax, candelilla wax, jojoba oil, wood wax, beeswax, ibota wax, lanolin, montanic acid ester wax, etc. can be mentioned.

[0086] Examples of the paraffin waxes include polyethylene waxes, polypropylene waxes, and the like.

[0087] The content of the release agent is preferably 4% by mass or more and 20% by mass or less, more preferably 6% by mass or more and 15% by mass or less, based on the total toner particles.

[0088] -Other Additives- Examples of the other additives include known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in the toner particles as internal additives.

[0089] -Properties of Toner Particles, etc.- The toner particles may be single-layer structured toner particles, or may be so-called core-shell structured toner particles composed of a core part (core particles) and a coating layer (shell layer) that coats the core part. Here, the core-shell structured toner particles may preferably be composed of a core part containing a binder resin and other additives such as a colorant and a release agent as necessary, and a coating layer containing a binder resin.

[0090] As the volume average particle diameter (D50v) of the toner particles, 2 μm or more and 15 μm or less is preferable, and 4 μm or more and 8 μm or less is more preferable.

[0091] In addition, various average particle diameters and various particle size distribution indexes of the toner particles are measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolytic solution is ISOTON-II (manufactured by Beckman Coulter). At the time of measurement, as a dispersant, 0.5 mg or more and 50 mg or less of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant (sodium alkylbenzene sulfonate is preferable). This is added to 100 ml or more and 150 ml or less of the electrolytic solution. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a particle diameter in the range of 2 μm or more and 60 μm or less is measured using an aperture having an aperture diameter of 100 μm by a Coulter Multisizer II. The number of particles to be sampled is 50,000. Based on the measured particle size distribution, cumulative distributions of volume and number are drawn for the particle size ranges (channels) divided, and the particle diameter at which the cumulative value becomes 16% is defined as the volume particle diameter D16v, the number particle diameter D16p, the particle diameter at which the cumulative value becomes 50% is defined as the volume average particle diameter D50v, the cumulative number average particle diameter D50p, and the particle diameter at which the cumulative value becomes 84% is defined as the volume particle diameter D84v and the number particle diameter D84p. Using these, the volume particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 , and the number particle size distribution index (GSDp) is (D84p / D16p) 1 / 2 and is calculated as such.

[0092] The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, more preferably 0.95 or more and 0.98 or less.

[0093] The average circularity of the toner particles is obtained by (equivalent circumference of a circle) / (circumference) [(circumference of a circle having the same projected area as the particle image) / (circumference of the particle projection image)]. Specifically, it is a value measured by the following method. First, the toner particles to be measured are aspirated and collected, a flat flow is formed, and stroboscopic light emission is instantaneously performed to capture the particle image as a still image, and the particle image is obtained by a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation) for image analysis. The number of samplings when obtaining the average circularity is set to 3500. When the toner has an external additive, toner particles from which the external additive has been removed are obtained by dispersing the toner (developer) to be measured in water containing a surfactant and then performing ultrasonic treatment.

[0094] (External additive) Examples of the external additive include inorganic particles. Examples of the inorganic particles include SiO 2 , TiO 2 , Al 2 O 3 , CuO, ZnO, SnO 2 , CeO 2 , Fe 2 O 3 , MgO, BaO, CaO, K 2 O, Na 2 O, ZrO 2 , CaO·SiO 2 , K 2 O·(TiO 2 )n, Al 2 O 3 ·2SiO 2 , CaCO 3 , MgCO 3 , BaSO 4 , MgSO 4 and the like.

[0095] The surface of the inorganic particles as an external additive is preferably subjected to a hydrophobization treatment. The hydrophobization treatment is performed, for example, by immersing the inorganic particles in a hydrophobization treatment agent. The hydrophobization treatment agent is not particularly limited, and examples thereof include silane-based coupling agents, silicone oils, titanate-based coupling agents, aluminum-based coupling agents, and the like. These may be used alone or in combination of two or more. As the amount of the hydrophobization treatment agent, usually, for example, it is 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the inorganic particles.

[0096] Examples of the external additive also include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning agents (for example, metal salts of higher fatty acids represented by zinc stearate, particles of fluorine-based high molecular weight substances), and the like.

[0097] As the addition amount of the external additive, for example, with respect to the toner particles, 0.01% by mass or more and 5% by mass or less is preferable, and 0.01% by mass or more and 2.0% by mass or less is more preferable.

[0098] (Method for manufacturing toner) Next, the method for manufacturing the toner according to the present embodiment will be described. The toner according to the present embodiment is obtained by adding an external additive to the toner particles after manufacturing the toner particles.

[0099] The toner particles may be manufactured by any of a dry method (for example, a kneading and pulverizing method, etc.) or a wet method (for example, an aggregation and coagulation method, a suspension polymerization method, a dissolution and suspension method, etc.). The manufacturing method of the toner particles is not particularly limited to these methods, and well-known manufacturing methods are adopted. Among these, from the viewpoint of making the domain of the crystalline resin satisfy the above conditions, it is preferable to obtain the toner particles by the aggregation and coagulation method.

[0100] Specifically, for example, when manufacturing the toner particles by the aggregation and coagulation method, A step of preparing an amorphous resin particle dispersion in which amorphous resin particles are dispersed, a crystalline resin particle dispersion in which crystalline resin particles are dispersed, and a release agent particle dispersion in which release agent particles are dispersed (particle dispersion preparation step); In a dispersion obtained by mixing the amorphous resin particle dispersion, the crystalline resin particle dispersion, and the release agent particle dispersion (in the dispersion after mixing a colorant dispersion as necessary), aggregating the amorphous resin particles, the crystalline resin particles, and the release agent particles (colorant, etc. as necessary) to form first aggregated particles (first aggregated particle formation step); After obtaining an aggregated particle dispersion in which the first aggregated particles are dispersed, mixing the aggregated particle dispersion with the amorphous resin particle dispersion and the crystalline resin particle dispersion (or mixing the aggregated particle dispersion with a mixture of the amorphous resin particle dispersion and the crystalline resin particle dispersion), and repeating the operation of aggregating so that amorphous resin particles and crystalline resin particles further adhere to the surface of the first aggregated particles one or more times to form second aggregated particles (second aggregated particle step); After obtaining an aggregated particle dispersion in which the second aggregated particles are dispersed, mixing the aggregated particle dispersion with the amorphous resin particle dispersion, aggregating so that amorphous resin particles adhere to the surface of the second aggregated particles, and forming third aggregated particles (third aggregated particle step); Heating the aggregated particle dispersion in which the third aggregated particles are dispersed, fusing and uniting the aggregated particles (first united particles), and then sequentially performing rapid cooling, reheating, and slow cooling (first cooled particles) to form particles in which the toner particles are fused and united (second united particles); After passing through the above steps, cooling again (second cooled particles) to produce toner particles.

[0101] Hereinafter, the details of each step will be described. In the following description, a method for obtaining toner particles containing a colorant and a release agent will be described, but the colorant is used as necessary. Of course, other additives other than the colorant may be used.

[0102] - Resin Particle Dispersion Preparation Step - First, together with each resin particle dispersion liquid (an amorphous resin particle dispersion liquid and a crystalline resin particle dispersion liquid) in which each resin particle serving as a binder resin is dispersed, for example, a colorant particle dispersion liquid in which colorant particles are dispersed and a release agent particle dispersion liquid in which release agent particles are dispersed are prepared.

[0103] Here, the resin particle dispersion liquid is prepared, for example, by dispersing resin particles in a dispersion medium with a surfactant.

[0104] Examples of the dispersion medium used for the resin particle dispersion liquid include aqueous media. Examples of the aqueous medium include water such as distilled water and ion-exchanged water, and alcohols. These may be used alone or in combination of two or more.

[0105] Examples of the surfactant include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, particularly, anionic surfactants and cationic surfactants are mentioned. The nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant. The surfactant may be used alone or in combination of two or more.

[0106] In the resin particle dispersion liquid, examples of the method for dispersing resin particles in a dispersion medium include general dispersion methods such as a rotary shear type homogenizer and a ball mill, a sand mill, a dyno mill, etc. having media. Also, depending on the type of resin particles, for example, the phase inversion emulsification method may be used to disperse the resin particles in the resin particle dispersion liquid. The phase inversion emulsification method is a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase), and after neutralization, an aqueous medium (W phase) is introduced, whereby the conversion of the resin from W / O to O / W (so-called phase inversion) occurs to form a discontinuous phase, and the resin is dispersed in the aqueous medium in the form of particles.

[0107] The volume average particle diameter of the resin particles dispersed in the resin particle dispersion is preferably, for example, 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and even more preferably 0.1 μm or more and 0.6 μm or less. The volume average particle diameter of the resin particles is measured as the volume average particle diameter D50v by using the particle size distribution obtained by measurement with a laser diffraction particle size distribution measuring device (for example, LA-700 manufactured by Horiba, Ltd.), subtracting the cumulative distribution from the small particle size side with respect to the volume for the divided particle size ranges (channels), and taking the particle diameter at which the cumulative percentage is 50% with respect to all the particles. The volume average particle diameter of the particles in other dispersions is also measured in the same manner.

[0108] The content of the resin particles contained in the resin particle dispersion is preferably, for example, 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0109] In the same manner as the resin particle dispersion, for example, a colorant particle dispersion and a mold release agent particle dispersion are also prepared. That is, regarding the volume average particle diameter, dispersion medium, dispersion method, and content of the particles in the resin particle dispersion, the same applies to the colorant particles dispersed in the colorant particle dispersion and the mold release agent particles dispersed in the mold release agent particle dispersion.

[0110] -First Agglomerated Particle Formation Step- Next, the colorant particle dispersion and the mold release agent particle dispersion are mixed together with the amorphous resin particle dispersion and the crystalline resin particle dispersion. Then, in the mixed dispersion liquid, hetero-aggregation of amorphous resin particles, crystalline resin particles, colorant particles, and release agent particles is performed to form first aggregated particles containing amorphous resin particles, crystalline resin particles, colorant particles, and release agent particles, which have a diameter close to the diameter of the target toner particles.

[0111] Specifically, for example, a flocculant is added to the mixed dispersion liquid, the pH of the mixed dispersion liquid is adjusted to be acidic (for example, the pH is 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. Then, after heating to the temperature of the glass transition temperature of the amorphous resin particles (specifically, for example, the glass transition temperature of the amorphous resin particles is -30°C or more and -10°C or less), the particles dispersed in the mixed dispersion liquid are aggregated to form first aggregated particles. In the first aggregated particle forming step, for example, while stirring the mixed dispersion liquid with a rotary shear homogenizer, the above-mentioned flocculant is added at room temperature (for example, 25°C), the pH of the mixed dispersion liquid is adjusted to be acidic (for example, the pH is 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. Then, the above-mentioned heating may be performed.

[0112] Examples of the flocculant include surfactants with opposite polarities to the surfactants used as dispersants added to the mixed dispersion liquid, inorganic metal salts, and metal complexes with a valence of 2 or more. In particular, when a metal complex is used as the flocculant, the amount of surfactant used is reduced, and the charging characteristics are improved. An additive that forms a complex or a similar bond with the metal ions of the flocculant may be used as necessary. As this additive, a chelating agent is preferably used.

[0113] Examples of the inorganic metal salts include metal salts such as 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. As the chelating agent, a water-soluble chelating agent may be used. Examples of the chelating agent include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). As the addition amount of the chelating agent, for example, 0.01 part by mass or more and 5.0 parts by mass or less, preferably 0.1 part by mass or more and less than 3.0 parts by mass, per 100 parts by mass of the amorphous resin particles is preferable.

[0114] -Second Agglomerated Particle Formation Step- Next, after obtaining an agglomerated particle dispersion in which the first agglomerated particles are dispersed, the agglomerated particle dispersion is mixed with the amorphous resin particle dispersion and the crystalline resin particle dispersion. The agglomerated particle dispersion may be mixed with a mixture of the amorphous resin particle dispersion and the crystalline resin particle dispersion.

[0115] Then, in the dispersion in which the first agglomerated particles, the amorphous resin particles, and the crystalline resin particles are dispersed, the amorphous resin particles and the crystalline resin particles are agglomerated on the surface of the first agglomerated particles. Specifically, for example, in the first agglomerated particle formation step, when the first agglomerated particles reach the target particle size, the amorphous resin particle dispersion and the crystalline resin particle dispersion are added to the second agglomerated particle dispersion, and this dispersion is heated below the glass transition temperature of the amorphous resin particles. This agglomeration operation is repeated one or more times to form the second agglomerated particles.

[0116] -Third Agglomerated Particle Formation Step- After obtaining an agglomerated particle dispersion in which the second agglomerated particles are dispersed, the agglomerated particle dispersion is mixed with the amorphous resin particle dispersion.

[0117] Then, in the dispersion in which the second agglomerated particles and the amorphous resin particles are dispersed, the amorphous resin particles are agglomerated on the surface of the second agglomerated particles. Specifically, for example, in the second agglomerated particle formation step, when the second agglomerated particles reach the target particle size, the amorphous resin particle dispersion is added to the second agglomerated particle dispersion, and this dispersion is heated below the glass transition temperature of the amorphous resin particles. Then, the pH of the dispersion is adjusted to stop the progress of agglomeration.

[0118] -Fusion and Unification Step- Next, with respect to the third aggregated particle dispersion liquid in which the third aggregated particles are dispersed, for example, it is heated to a temperature equal to or higher than the glass transition temperature of the amorphous resin particles (for example, a temperature equal to or higher than 10 to 30 °C higher than the glass transition temperature of the amorphous resin particles), and the aggregated particles are fused and united to form toner particles.

[0119] Here, when fusing and uniting the aggregated particles by heating, first, the temperature is raised to a range from the melting temperature of the crystalline resin to the melting temperature + 20 °C, and then held. While maintaining the state in which the mold release agent particles in the third aggregated particles are dispersed, the crystalline resin particles are fused to obtain first united particles. Next, after gradually cooling (for example, gradually cooling at a cooling rate of 0.7 °C / min or less) to a range from (melting temperature - 50 °C) to (melting temperature - 5 °C) of the crystalline resin and then holding, the domain of the crystalline resin is grown to obtain first cooled particles. Next, after raising the temperature to the fusion and unification temperature (a temperature equal to or higher than the glass transition temperature of the amorphous resin) and then holding, the mold release agent particles are fused to obtain second united particles. By performing these operations, the fused portion of the crystalline resin particles and the fused portion of the mold release agent particles can be separated. Next, by gradually cooling (for example, gradually cooling at a cooling rate of 0.7 °C / min or less) to a temperature of 40 °C or lower, the domains of the crystalline resin and the mold release agent are grown without contacting each other to obtain second cooled particles.

[0120] Through the above steps, toner particles satisfying condition (A1) and condition (B1) or condition (A2) and condition (B2) are obtained. In particular, when performing the above operations, toner particles satisfying condition (C1) in which the domain of the crystalline resin is needle-shaped or plate-shaped and the domain of the mold release agent is circular are easily obtained. Note that toner particles satisfying condition (C2) in which the domain of the crystalline resin is circular and the domain of the mold release agent is needle-shaped or plate-shaped can be obtained, for example, by performing the following operations. When fusing and uniting the aggregated particles by heating, first, the temperature is raised to a range from the melting temperature of the crystalline resin to the melting temperature + 20 °C, and then held. While maintaining the state in which the mold release agent particles in the third aggregated particles are dispersed, the crystalline resin particles are fused. Next, the crystalline resin is rapidly cooled (for example, cooled at a cooling rate of 1°C / min or more and 4°C / min or less) to the range from (melting temperature - 50°C) to (melting temperature - 10°C) to put the crystalline resin in a supercooled state. After the supercooled state is achieved, the crystalline resin is held at a temperature of melting temperature - 50 or more and - 10°C or less so that the crystalline resin can form a lamellar structure, thereby forming a lamellar structure of the crystalline resin and making it possible to make the domains of the crystalline resin circular. And by the above operation, the domains of the release agent become needle-shaped or plate-shaped. Note that if supercooling is performed at an excessive cooling rate, the diameters of the domains of the release agent become smaller and the diameters are reduced.

[0121] Here, after the fusion and coalescence step is completed, the toner particles formed in the solution are dried through known cleaning steps, solid-liquid separation steps, and drying steps to obtain toner particles in a dried state. In the cleaning step, it is preferable to perform substitution cleaning sufficiently with ion-exchanged water from the viewpoint of chargeability. Also, in the solid-liquid separation step, although there is no particular limitation, it is preferable to perform suction filtration, pressure filtration, etc. from the viewpoint of productivity. Also, in the drying step, although there is no particular limitation on the method, it is preferable to perform freeze drying, airflow drying, fluidized drying, vibration type fluidized drying, etc. from the viewpoint of productivity.

[0122] And the toner according to the present embodiment is manufactured, for example, by adding and mixing an external additive to the obtained toner particles in a dried state. The mixing is preferably performed by, for example, a V blender, a Henschel mixer, a Lodige mixer, etc. Further, if necessary, coarse particles of the toner may be removed using a vibration sieve, an air classifier, etc.

[0123] <Electrostatic charge image developer> The electrostatic charge image developer according to the present embodiment includes at least the toner according to the present embodiment. The electrostatic charge image developer according to the present embodiment may be a one-component developer containing only the toner according to the present embodiment, or may be a two-component developer in which the toner and a carrier are mixed.

[0124] The carrier is not particularly limited, and known carriers can be mentioned. Examples of the carrier include a coated carrier in which a coating resin is coated on the surface of a core material made of magnetic powder; a magnetic powder-dispersed carrier in which magnetic powder is dispersed and blended in a matrix resin; a resin-impregnated carrier in which porous magnetic powder is impregnated with resin; and the like. Note that the magnetic powder-dispersed carrier and the resin-impregnated carrier may be carriers in which the constituent particles of the carrier are used as the core material and coated with a coating resin.

[0125] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0126] Examples of the coating resin and the matrix resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic ester copolymer, straight silicone resin or its modified product composed of an organosiloxane bond, fluororesin, polyester, polycarbonate, phenol resin, epoxy resin, and the like. Note that the coating resin and the matrix resin may contain other additives such as conductive particles. Examples of the conductive particles include metals such as gold, silver, and copper, and particles such as carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0127] Here, to coat the surface of the core material with a coating resin, methods such as coating with a coating layer-forming solution in which the coating resin and various additives as required are dissolved in an appropriate solvent can be mentioned. The solvent is not particularly limited and may be selected in consideration of the coating resin to be used, coating suitability, and the like. Specific resin coating methods include an immersion method in which the core material is immersed in a coating layer forming solution, a spray method in which the coating layer forming solution is sprayed onto the surface of the core material, a fluidized bed method in which the coating layer forming solution is sprayed while the core material is suspended by flowing air, a kneader coater method in which the core material of the carrier and the coating layer forming solution are mixed in a kneader coater and the solvent is removed, and the like.

[0128] In the two-component developer, the mixing ratio (mass ratio) of the toner and the carrier is preferably toner:carrier = 1:100 to 30:100, and more preferably 3:100 to 20:100.

[0129] <Image forming apparatus / Image forming method> The image forming apparatus / image forming method according to this embodiment will be described. The image forming apparatus according to this embodiment includes an image carrier, a charging unit that charges the surface of the image carrier, an electrostatic charge image forming unit that forms an electrostatic charge image on the charged surface of the image carrier, a developing unit that stores an electrostatic charge image developer and develops the electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer, a transfer unit that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing unit that fixes the toner image transferred to the surface of the recording medium. And, as the electrostatic charge image developer, the electrostatic charge image developer according to this embodiment is applied.

[0130] In the image forming apparatus according to this embodiment, an image forming method (the image forming method according to this embodiment) including a charging step of charging the surface of the image carrier, an electrostatic charge image forming step of forming an electrostatic charge image on the charged surface of the image carrier, a developing step of developing the electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to this embodiment, a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium is performed.

[0131] The image forming apparatus according to the present embodiment is a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image carrier to a recording medium; an intermediate transfer type apparatus that first transfers a toner image formed on the surface of an image carrier to the surface of an intermediate transfer member and then secondarily transfers the toner image transferred to the surface of the intermediate transfer member to the surface of a recording medium; an apparatus provided with cleaning means for cleaning the surface of the image carrier before charging after the transfer of the toner image; an apparatus provided with charge elimination means for irradiating the surface of the image carrier with charge elimination light for charge elimination before charging after the transfer of the toner image, etc. Well-known image forming apparatuses are applicable. In the case of an intermediate transfer type apparatus, the transfer means has, for example, a configuration including an intermediate transfer member on which a toner image is transferred to the surface, a primary transfer means for primarily transferring the toner image formed on the surface of the image carrier to the surface of the intermediate transfer member, and a secondary transfer means for secondarily transferring the toner image transferred to the surface of the intermediate transfer member to the surface of the recording medium.

[0132] In the image forming apparatus according to the present embodiment, for example, a portion including the developing means may be a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge including developing means that stores the electrostatic charge image developer according to the present embodiment is preferably used.

[0133] Hereinafter, an example of the image forming apparatus according to the present embodiment is shown, but it is not necessarily limited thereto. Note that the main parts shown in the drawings are described, and the description of the others is omitted.

[0134] FIG. 1 is a schematic configuration diagram showing the image forming apparatus according to the present embodiment. The image forming apparatus shown in Fig. 1 includes electrophotographic first to fourth image forming units 10Y, 10M, 10C, 10K (image forming means) that output images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter may be simply referred to as "units") 10Y, 10M, 10C, 10K are arranged side by side at a predetermined distance from each other in the horizontal direction. Note that these units 10Y, 10M, 10C, 10K may be process cartridges that are detachable from the image forming apparatus.

[0135] Above each of the units 10Y, 10M, 10C, 10K in the drawing, an intermediate transfer belt 20 as an intermediate transfer member extends through each unit. The intermediate transfer belt 20 is provided by being wound around a driving roll 22 and a support roll 24 that is in contact with the inner surface of the intermediate transfer belt 20 and is arranged at a distance from each other in the left-to-right direction in the drawing, and is configured to travel in the direction from the first unit 10Y to the fourth unit 10K. Note that a force is applied to the support roll 24 in a direction away from the driving roll 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around both of them. Further, an intermediate transfer member cleaning device 30 is provided on the side surface of the image holding body of the intermediate transfer belt 20 so as to face the driving roll 22. In addition, each of the developing devices (developing means) 4Y, 4M, 4C, 4K of the units 10Y, 10M, 10C, 10K is supplied with toner including four colors of toner of yellow, magenta, cyan, and black stored in toner cartridges 8Y, 8M, 8C, 8K.

[0136] Since the first to fourth units 10Y, 10M, 10C, 10K have the same configuration, here, the first unit 10Y that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction will be described as a representative. Note that the description of the second to fourth units 10M, 10C, 10K is omitted by attaching reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) to the parts equivalent to the first unit 10Y.

[0137] The first unit 10Y has a photoreceptor 1Y that acts as an image holding member. Around the photoreceptor 1Y, there are arranged in order a charging roll (an example of charging means) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, an exposure device (an example of electrostatic charge image forming means) 3 that exposes the charged surface with a laser beam 3Y based on a color-separated image signal to form an electrostatic charge image, a developing device (an example of developing means) 4Y that supplies toner charged to the electrostatic charge image to develop the electrostatic charge image, a primary transfer roll (an example of primary transfer means) 5Y that transfers the developed toner image onto an intermediate transfer belt 20, and a photoreceptor cleaning device (an example of cleaning means) 6Y that removes the toner remaining on the surface of the photoreceptor 1Y after primary transfer. Note that the primary transfer roll 5Y is disposed inside the intermediate transfer belt 20 and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

[0138] Hereinafter, the operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the photoreceptor 1Y is charged to a potential of -600 V to -800 V by the charging roll 2Y. The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (for example, volume resistivity at 20°C: 1×10 -6 Ωcm or less). This photosensitive layer is usually of high resistance (resistance of a general resin), but has the property that the specific resistance of the portion irradiated with the laser beam 3Y changes when irradiated with the laser beam 3Y. Therefore, the laser beam 3Y is output through the exposure device 3 in accordance with the yellow image data sent from a control unit (not shown) to the charged surface of the photoreceptor 1Y. The laser beam 3Y is irradiated onto the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic charge image of the yellow image pattern is formed on the surface of the photoreceptor 1Y.

[0139] The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y due to charging. By the laser beam 3Y, the specific resistance of the irradiated portion of the photosensitive layer decreases, and the charged charges on the surface of the photoreceptor 1Y flow. On the other hand, it is a so-called negative latent image formed by the remaining charges in the portion not irradiated by the laser beam 3Y. The electrostatic charge image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y travels. And at this development position, the electrostatic charge image on the photoreceptor 1Y is visualized as a toner image (developed image) by the developing device 4Y.

[0140] In the developing device 4Y, for example, an electrostatic charge image developer containing at least yellow toner and carrier is accommodated. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y and has the same polarity (negative polarity) as the charged charges on the photoreceptor 1Y and is held on the developer roll (an example of a developer holding member). And as the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed by the yellow toner. The photoreceptor 1Y on which the yellow toner image is formed continues to travel at a predetermined speed, and the toner image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer position.

[0141] When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and the electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y acts on the toner image, and the toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has the opposite polarity (+) to the polarity (-) of the toner. For example, in the first unit 10Y, it is controlled to +10 μA by the control unit (not shown). On the other hand, the toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0142] Also, the primary transfer biases applied to the primary transfer rolls 5M, 5C, 5K after the second unit 10M are also controlled according to the first unit. In this way, the intermediate transfer belt 20 onto which the yellow toner image has been transferred in the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and toner images of each color are overlaid and multi-transferred.

[0143] The intermediate transfer belt 20 onto which four-color toner images have been multi-transferred through the first to fourth units reaches a secondary transfer section composed of the intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of secondary transfer means) 26 disposed on the image holding surface side of the intermediate transfer belt 20. On the other hand, a recording paper (an example of a recording medium) P is fed at a predetermined timing into the gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact via a supply mechanism, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has a (-) polarity that is the same polarity as the polarity of the toner (-), and an electrostatic force directed from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, and the toner image on the intermediate transfer belt 20 is transferred onto the recording paper P. Note that the secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer section and is voltage-controlled.

[0144] Thereafter, the recording paper P is fed into the pressure contact section (nip section) of a pair of fixing rolls in a fixing device (an example of fixing means) 28, and the toner image is fixed onto the recording paper P, forming a fixed image.

[0145] Examples of the recording paper P for transferring the toner image include plain paper used in electrophotographic copiers, printers, etc. Examples of the recording medium other than the recording paper P also include OHP sheets. In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper obtained by coating the surface of plain paper with resin or the like, art paper for printing, etc. are preferably used.

[0146] The recording paper P on which the fixing of the color image has been completed is carried out toward the discharge section, and a series of color image forming operations are completed.

[0147] <Process cartridge / Toner cartridge> A process cartridge according to the present embodiment will be described. The process cartridge according to the present embodiment contains the electrostatic charge image developer according to the present embodiment, and includes developing means for developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer, and is a process cartridge that is detachable from the image forming apparatus.

[0148] Note that the process cartridge according to the present embodiment is not limited to the above configuration, and may be configured to include a developing device and at least one selected from other means such as, for example, an image carrier, charging means, electrostatic charge image forming means, and transfer means as necessary.

[0149] Hereinafter, an example of the process cartridge according to the present embodiment is shown, but it is not limited thereto. Note that the main parts shown in the drawings will be described, and the description of the others will be omitted.

[0150] FIG. 2 is a schematic configuration diagram showing the process cartridge according to the present embodiment. The process cartridge 200 shown in FIG. 2 is configured by integrally combining and holding, for example, a photosensitive member 107 (an example of an image carrier), a charging roll 108 (an example of charging means) provided around the photosensitive member 107, a developing device 111 (an example of developing means), and a photosensitive member cleaning device 113 (an example of cleaning means) with a housing 117 provided with an attachment rail 116 and an opening 118 for exposure, and is made into a cartridge. Note that in FIG. 2, 109 indicates an exposure device (an example of electrostatic charge image forming means), 112 indicates a transfer device (an example of transfer means), 115 indicates a fixing device (an example of fixing means), and 300 indicates a recording paper (an example of a recording medium).

[0151] Next, the toner cartridge according to the present embodiment will be described. The toner cartridge according to this embodiment is a toner cartridge that houses the toner according to this embodiment and is detachable from the image forming apparatus. The toner cartridge houses replenishing toner for supplying the developing means provided in the image forming apparatus.

[0152] Note that the image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K are detachable, and the developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to the respective developing devices (colors) by toner supply pipes (not shown). Further, when the amount of toner housed in the toner cartridge decreases, the toner cartridge is replaced.

Example

[0153] Hereinafter, examples and comparative examples will be given to describe this embodiment in more specific detail, but this embodiment is not limited to these examples at all. Note that "parts" and "%" indicating amounts are based on mass unless otherwise specified.

[0154] <Production of amorphous resin> (Production of amorphous polyester resin (A)) ·Terephthalic acid: 70 parts ·Fumaric acid: 30 parts ·Ethylene glycol: 41 parts ·1,5-Pentanediol: 48 parts The above materials were charged into a 5-liter flask equipped with a stirring device, a nitrogen introduction tube, a temperature sensor, and a rectification column, and the temperature was raised to 220°C over 1 hour under a nitrogen gas stream. 1 part of titanium tetraethoxide was added to 100 parts of the above materials. The temperature was raised to 240°C over 0.5 hour while distilling off the generated water, and the dehydration condensation reaction was continued at this temperature for 1 hour, and then the reaction product was cooled. Thus, an amorphous polyester resin (A) having a weight average molecular weight of 96000 and a glass transition temperature of 61°C was synthesized.

[0155] <Production of amorphous resin particle dispersion> (Preparation of Amorphous Polyester Resin Particles Dispersion (A1)) Into a container equipped with a temperature control means and a nitrogen replacement means, 40 parts of ethyl acetate and 25 parts of 2-butanol were charged to obtain a mixed solvent. Then, 100 parts of an amorphous polyester resin (A) was gradually charged and dissolved. Here, a 10% aqueous ammonia solution (equivalent to 3 times the molar ratio based on the acid value of the resin) was added and stirred for 30 minutes. Next, the inside of the container was replaced with dry nitrogen, the temperature was maintained at 40 °C, and while stirring the mixed solution, 400 parts of ion-exchanged water was added dropwise at a rate of 2 parts / minute to perform emulsification. After the completion of the dropping, the emulsion was returned to 25 °C to obtain a resin particles dispersion in which resin particles with a volume average particle diameter of 190 nm were dispersed. Ion-exchanged water was added to the resin particles dispersion to adjust the solid content to 20% to obtain an amorphous polyester resin particles dispersion (A1).

[0156] <Preparation of Crystalline Resin> (Preparation of Crystalline Polyester Resin (B)) ·1,10-Decanedicarboxylic acid: 265 parts ·1,6-Hexanediol: 168 parts ·Dibutyltin oxide (catalyst): 0.3 parts by mass After putting the above components into a heated and dried three-necked flask, the air inside the container was made into an inert atmosphere with nitrogen gas by a vacuum operation, and stirring and refluxing were carried out at 180 °C for 5 hours with mechanical stirring. Then, the temperature was gradually raised to 230 °C under reduced pressure and stirred for 2 hours. When it became viscous, it was air-cooled to stop the reaction. By molecular weight measurement (polystyrene conversion), the weight average molecular weight (Mw) of the obtained "crystalline polyester resin (B)" was 12700, and the melting temperature was 73 °C.

[0157] <Preparation of Crystalline Polyester Resin Particles Dispersion> (Preparation of Crystalline Polyester Resin Particles Dispersion (B1)) 90 parts by mass of crystalline polyester resin (B), 1.8 parts by mass of ionic surfactant Neogen RK (Daiichi Kogyo Seiyaku Co., Ltd.), and 210 parts by mass of ion-exchanged water were used. After heating to 120 °C and sufficiently dispersing with an Ultra Turrax T50 manufactured by IKA, a dispersion treatment was performed for 1 hour with a pressure discharge type Gorin homogenizer to obtain a crystalline polyester resin particle dispersion (B1) having a volume average particle diameter of 190 nm and a solid content of 20 parts by mass.

[0158] (Preparation of colorant particle dispersion) · Carbon black (Regal 330, manufactured by Cabot Corporation): 50 parts · Ionic surfactant Neogen RK (Daiichi Kogyo Seiyaku Co., Ltd.): 5 parts · Ion-exchanged water: 193 parts The above components were mixed and treated at 240 MPa for 10 minutes with an Altimizer (manufactured by Sugino Machine Limited) to prepare a colorant particle dispersion (solid content concentration: 20%).

[0159] <Preparation of release agent particle dispersion> (Preparation of release agent particle dispersion (W1)) · Ester wax (WEP-5, manufactured by NOF Corporation, melting temperature 85 °C): 100 parts · Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part · Ion-exchanged water: 350 parts The above materials were mixed, heated to 100 °C, dispersed using a homogenizer (Ultra Turrax T50 manufactured by IKA), and then dispersed with a Manton Gorin high-pressure homogenizer (manufactured by Gorin Corporation) to obtain a release agent particle dispersion (W1) (solid content 20%) in which release agent particles having a volume average particle diameter of 220 nm were dispersed.

[0160] (Preparation of release agent particle dispersion (W2)) · Ester wax (WEP-9, manufactured by NOF Corporation, melting temperature 67 °C): 100 parts · Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part · Ion-exchanged water: 350 parts 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 Gorin high-pressure homogenizer (manufactured by Gorin) to obtain a mold release agent particle dispersion (W2) (solid content: 20%) in which mold release agent particles with a volume average particle diameter of 220 nm were dispersed.

[0161] (Preparation of mold release agent particle dispersion (W3)) · Ester wax (WEP-2 manufactured by NOF Corporation, melting point: 60 °C): 100 parts · Anionic surfactant (Neogen RK manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 1 part · Ion-exchanged water: 350 parts 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 Gorin high-pressure homogenizer (manufactured by Gorin) to obtain a mold release agent particle dispersion (W3) (solid content: 20%) in which mold release agent particles with a volume average particle diameter of 220 nm were dispersed.

[0162] (Preparation of mold release agent particle dispersion (W4)) · Paraffin wax (HNP-9 manufactured by Nippon Seiro Co., Ltd., melting point: 75 °C): 100 parts · Anionic surfactant (Neogen RK manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 1 part · Ion-exchanged water: 350 parts 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 Gorin high-pressure homogenizer (manufactured by Gorin) to obtain a mold release agent particle dispersion (W4) (solid content: 20%) in which mold release agent particles with a volume average particle diameter of 220 nm were dispersed.

[0163] (Preparation of mold release agent particle dispersion (W5)) · Polyethylene wax (PW600 manufactured by Toyo Adres Co., Ltd., melting point: 91 °C): 100 parts · Anionic surfactant (Neogen RK manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 1 part · Ion-exchanged water: 350 parts 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 mold release agent particle dispersion (W5) (solid content: 20%) in which mold release agent particles with a volume average particle diameter of 220 nm were dispersed.

[0164] (Preparation of mold release agent particle dispersion (W6)) · Paraffin wax (FT-100, melting temperature 98 °C, manufactured by Nippon Seiro Co., Ltd.): 100 parts · Anionic surfactant (Neogen RK, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 1 part · Ion-exchanged water: 350 parts 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 mold release agent particle dispersion (W5) (solid content: 20%) in which mold release agent particles with a volume average particle diameter of 220 nm were dispersed.

[0165] <Example 1> - Preparation of toner particles - · Amorphous polyester resin particle dispersion (A1): 240 parts (solid content: 20%) · Crystalline polyester resin particle dispersion (B1): 50 parts (solid content: 20%) · Colorant particle dispersion: 20 parts (solid content: 20%) · Mold release agent particle dispersion (W1): 40 parts (solid content: 20%) · Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd.: Neogen RK, 20%): 2.8 parts · Ion-exchanged water: 215 parts The above components were placed in a 3-liter reaction vessel equipped with a thermometer, a pH meter, and a stirrer, and maintained at a temperature of 30 °C and a stirring speed of 150 rpm for 30 minutes while controlling the temperature with an external mantle heater. Then, a 0.3N nitric acid aqueous solution was added to adjust the pH to 3.0 in the aggregation step.

[0166] While dispersing with a homogenizer (manufactured by IKA Japan Co., Ltd.: ULTRA-TURRAX T50), an aqueous PAC solution in which 0.7 part of PAC (manufactured by Oji Paper Co., Ltd.: 30% powder product) was dissolved in 7 parts of ion-exchanged water was added. Then, while stirring, the temperature was raised to 50°C, and the particle size was measured with a Coulter Multisizer II (aperture diameter: 50 μm, manufactured by Coulter), and the volume average particle size was set to 4.6 μm. In this way, the first aggregated particles were obtained. Thereafter, 45 parts of the amorphous polyester resin particle dispersion (A1) and 30 parts of the crystalline polyester resin particle dispersion were additionally added to obtain second aggregated particles. After holding for 30 minutes, 75 parts of the amorphous polyester resin particle dispersion (A1) was further added to obtain third aggregated particles. Subsequently, 20 parts of a 10% NTA (nitrilotriacetic acid) metal salt aqueous solution (Kirest 70: manufactured by Kirest Co., Ltd.) was added, and then the pH was adjusted to 9.0 using 1N sodium hydroxide aqueous solution. Thereafter, the temperature was raised to the first coalescence temperature of 70°C, held at the first coalescence temperature for 30 minutes to obtain first coalesced particles, then slowly cooled to the first final cooling temperature of 63°C at a first cooling rate of 0.7°C / min to obtain first cooled particles, and then held for 30 minutes. Next, the temperature was raised to the second coalescence temperature of 87°C, held at the second coalescence time of 20 minutes to obtain second coalesced particles, then slowly cooled to the second final cooling temperature of 35°C at a second cooling rate of 0.7°C / min, and further maintained at 35°C for 30 minutes of the temperature after the second cooling to obtain second cooled particles. Thereafter, filtration was performed to obtain coarse toner particles. The coarse toner particles were further redispersed in ion-exchanged water and filtered repeatedly until the electrical conductivity of the filtrate became 20 μS / cm or less, and then vacuum dried in an oven at 40°C for 5 hours to obtain toner particles.

[0167] - Preparation of Toner - To 100 parts of the obtained toner particles, 1.5 parts of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., RY50) was mixed at 10,000 rpm for 30 seconds using a sample mill. Thereafter, sieving was performed with a vibrating sieve having a mesh opening of 45 μm to obtain toner.

[0168] <Examples 2 to 32, Comparative Examples 1 to 2> Toner particles were obtained in the same manner as in Example 1, except that the amount and type of the dispersion liquid, and the conditions of the first coalescing particles, the first cooling particles, the second coalescing particles, and the second cooling particles were changed according to Table 1.

[0169] <Comparative Example 3> · Amorphous polyester resin particle dispersion (A1): 240 parts (solid content 20%) · Crystalline polyester resin particle dispersion (B1): 80 parts (solid content 20%) · Release agent particle dispersion (W1): 40 parts (solid content 20%) · Colorant dispersion: 20 parts (solid content 20%) · Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd.: Neogen RK, 20%): 2.8 parts · Ion-exchanged water: 215 parts The above components were placed in a 3-liter reaction vessel equipped with a thermometer, a pH meter, and a stirrer, and while controlling the temperature with an external mantle heater, they were held at a temperature of 30°C and a stirring rotation speed of 150 rpm for 30 minutes. Then, a 0.3N nitric acid aqueous solution was added to adjust the pH to 3.0 in the aggregation step.

[0170] While dispersing with a homogenizer (Ultra Turrax T50 manufactured by IKA Japan), an aqueous PAC solution in which 0.7 part of PAC (powder product, 30% manufactured by Oji Paper Co., Ltd.) was dissolved in 7 parts of ion-exchanged water was added. Then, while stirring, the temperature was raised to 50°C, the particle size was measured with a Coulter Multisizer II (aperture diameter: 50 μm, manufactured by Coulter), and the volume average particle size was set to 4.6 μm. Then, 120 parts of the amorphous polyester resin particle dispersion (A1) was additionally added. Subsequently, 20 parts of a 10% aqueous solution of an NTA (nitrilotriacetic acid) metal salt (Krest 70: manufactured by Krest Co., Ltd.) was added, and then the pH was adjusted to 9.0 using a 1N aqueous sodium hydroxide solution. Thereafter, the temperature was raised to 87°C, held for 2 hours, then gradually cooled to 30°C at a cooling rate of 0.5°C / min, and filtered to obtain crude toner particles. The coarse toner particles were redispersed in ion-exchanged water and filtered repeatedly until the electric conductivity of the filtrate reached 20 μS / cm or less. After washing, the particles were vacuum-dried in an oven at 40 °C for 5 hours to obtain toner particles.

[0171] <Comparative Example 4> Toner particles were obtained in the same manner as in Comparative Example 3, except that the release agent particle dispersion (W1) used in Comparative Example 3 was changed to a release agent particle dispersion (W5).

[0172] <Properties> For the toner of each example, the following properties were measured according to the method described above. · Maximum diameter of toner particles · Domain diameter of crystalline resin · Aspect ratio or circularity of the domain of crystalline resin · Number of domains of crystalline resin with a domain diameter of 10% or more and 40% or less relative to the maximum diameter of toner particles (denoted as "number of large domains" in the table) · Domain diameter of release agent · Aspect ratio or circularity of the domain of release agent · Number of domains of release agent with a domain diameter of 10% or more and 40% or less relative to the maximum diameter of toner particles (denoted as "number of large domains" in the table)

[0173] · Ratio (number %) of toner particles A1 satisfying conditions (A1) and (B1) to all toner particles (100 particles measured) · Ratio (number %) of toner particles B1 satisfying conditions (A1), (B1), and (C11) to all toner particles (100 particles measured) · Ratio (number %) of toner particles C1 satisfying conditions (A1), (B1), and (C21) to all toner particles (100 particles measured) · Ratio (number %) of toner particles D1 satisfying conditions (A1), (B1), and (C12) to all toner particles (100 particles measured) · Ratio (number %) of toner particles E1 satisfying conditions (A1), (B1), and (C22) to all toner particles (100 particles measured)

[0174] · The ratio (number %) of toner particles A2 satisfying condition (A2) and condition (B2) to all toner particles (number of measurements: 100 particles) · The ratio (number %) of toner particles B2 satisfying condition (A2), condition (B2), and condition (C11) to all toner particles (number of measurements: 100 particles) · The ratio (number %) of toner particles C2 satisfying condition (A2), condition (B2), and condition (C21) to all toner particles (number of measurements: 100 particles) · The ratio (number %) of toner particles D2 satisfying condition (A2), condition (B2), and condition (C12) to all toner particles (number of measurements: 100 particles) · The ratio (number %) of toner particles E2 satisfying condition (A2), condition (B2), and condition (C22) to all toner particles (number of measurements: 100 particles)

[0175] Each condition is as follows. Condition (A1): There is one or more crystalline resin domains with a domain diameter of 10% or more and 40% or less with respect to the maximum diameter of the toner particles. Condition (B1): There is one or more release agent domains with a domain diameter of 10% or more and 40% or less with respect to the maximum diameter of the toner particles.

[0176] Condition (A2): There are a plurality of crystalline resin domains with a domain diameter of 10% or more and 40% or less with respect to the maximum diameter of the toner particles. Condition (B2): There are a plurality of release agent domains with a domain diameter of 10% or more and 40% or less with respect to the maximum diameter of the toner particles.

[0177] Condition (C11): The crystalline resin domain is needle-shaped or plate-shaped with an aspect ratio of 5 or more and 40 or less, and the release agent domain is circular with a circularity of 0.92 or more and 1.00. Condition (C21): The crystalline resin domain is circular with a circularity of 0.92 or more and 1.00, and the release agent domain is needle-shaped or plate-shaped with an aspect ratio of 5 or more and 40 or less.

[0178] Condition (C12): The domain of the crystalline resin is needle-shaped or plate-shaped with an aspect ratio of 15 or more and 40 or less, and the domain of the release agent is circular with a roundness of 0.95 or more and 1.00. Condition (C22): The domain of the crystalline resin is circular with a roundness of 0.92 or more and 1.00, and the domain of the release agent is needle-shaped or plate-shaped with an aspect ratio of 15 or more and 40 or less.

[0179] Table 1 shows the forms of the domains of the crystalline resin and the release agent in typical toner particles. Specifically, it is as follows.

[0180] <Evaluation> (Preparation of developer) Using the toner of each example, a developer was obtained as follows. 500 parts of spherical magnetite powder particles (volume average particle diameter: 0.55 μm) were sufficiently stirred in a Henschel mixer, then 5.0 parts of a titanate coupling agent were added, the temperature was raised to 100 °C, and the mixture was stirred for 30 minutes to obtain titanate coupling agent-coated spherical magnetite particles. Subsequently, 6.25 parts of phenol, 9.25 parts of 35% formalin, 500 parts of the above magnetite particles, 6.25 parts of 25% aqueous ammonia, and 425 parts of water were put into a four-necked flask and mixed and stirred. Next, after reacting at 85 °C for 120 minutes while stirring, it was cooled to 25 °C, 500 parts of water were added, the supernatant was removed, and the precipitate was washed with water. This was dried under reduced pressure at 150 °C or more and 180 °C or less to obtain a carrier with an average particle diameter of 35 μm. Then, the toner of each example and the obtained carrier were put into a V blender at a ratio of toner:carrier = 5:95 (mass ratio) and stirred for 20 minutes to obtain a developer.

[0181] (Gloss difference of image) Using the obtained developer, the gloss difference of the image was evaluated as follows. The developers obtained in each of the examples and comparative examples were respectively filled into the developing unit of the image forming apparatus "DocuCentre color 400 manufactured by Fuji Xerox Co., Ltd.". Using this image forming apparatus, 50 sheets of plain paper (manufactured by Canon Inc., product name: CS-520 A3) were output in a blank state at a process speed of 308 mm / s and a fixing temperature of 150°C in an environment of 28°C and 85% RH. Subsequently, 10 solid images (toner loading amount (TMA) 10.0 g / m 2 of the image) with a vertical length of 50 mm and a horizontal length of 280 mm were output at the tip of A3 with an image density of 100%. Regarding the first sheet of plain paper output and the solid image after 10 sheets were output, gloss was measured by the following method. For the measurement of gloss, using a portable gloss meter (BYK Gardner Microtri-Gloss, manufactured by Toyo Seiki Seisakusho Co., Ltd.), the measurement of 60-degree gloss was carried out at 5 locations. The difference was obtained from the measured values of gloss, and evaluation was carried out according to the following evaluation criteria. A: The gloss difference between the maximum value and the minimum value of gloss of the first and tenth output images is less than 3°. B: The gloss difference between the maximum value and the minimum value of gloss of the first and tenth output images is less than 4°. C: The gloss difference between the maximum value and the minimum value of gloss of the first and tenth output images is less than 6°. D: The gloss difference between the maximum value and the minimum value of gloss of the first and tenth output images is less than 8°. E: The gloss difference between the maximum value and the minimum value of gloss of the first and tenth output images is less than 10°. F: The gloss difference between the maximum value and the minimum value of gloss of the first and tenth output images is 10° or more.

[0182]

Table 1-1

[0183]

Table 1-2

[0184]

Table 1-3

[0185]

Table 1-4

[0186]

Table 1-5

[0187] From the above results, it can be seen that in this example, compared with the comparative example, when forming an image on a thin recording medium with high-speed and low-temperature fixing, the gloss difference between the first and the tenth images is suppressed.

Explanation of Signs

[0188] 1Y, 1M, 1C, 1K Photoconductor (an example of an image holding member) 2Y, 2M, 2C, 2K Charging roll (an example of a charging means) 3 Exposure device (an example of an electrostatic charge image forming means) 3Y, 3M, 3C, 3K Laser beam 4Y, 4M, 4C, 4K Developing device (an example of a developing means) 5Y, 5M, 5C, 5K Primary transfer roll (an example of a primary transfer means) 6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of a cleaning means) 8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt (an example of an intermediate transfer member) 22 Driving roll 24 Support roll 26 Secondary transfer roll (an example of a secondary transfer means) 30 Intermediate transfer member cleaning device 107 Photoconductor (an example of an image holding member) 108 Charging roll (an example of a charging means) 109 Exposure device (an example of an electrostatic charge image forming means) 111 Developing device (an example of a developing means) 112 Transfer device (an example of transfer means) 113 Photoconductor cleaning device (an example of cleaning means) 115 Fixing device (an example of fixing means) 116 Mounting rail 118 Opening for exposure 117 Housing 200 Process cartridge 300 Recording paper (an example of a recording medium) P Recording paper (an example of a recording medium)

Claims

A toner for electrostatic charge image development, comprising an amorphous resin, a crystalline resin, and a release agent, all containing a polyester resin, having toner particles that satisfy the following conditions (A1), (B1), and (D) when observing a cross-section of the toner particles, wherein the content of the toner particles is 30% by number or more based on all the toner particles. Condition (A1): There is one or more domains of the crystalline resin in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. Condition (B1): There is one or more domains of the release agent in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. Condition (D): All the domains of the crystalline resin and the release agent present in the toner particles exist in a state where they do not contact each other. **Claim 2** The toner for electrostatic charge image development according to claim 1, wherein when observing a cross-section of the toner particles, the toner particles satisfy the following conditions (A2), (B2), and (D). Condition (A2): There are a plurality of domains of the crystalline resin in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. Condition (B2): There are a plurality of domains of the release agent in which the domain diameter with respect to the maximum diameter of the toner particles is 10% or more and 40% or less. Condition (D): All the domains of the crystalline resin and the release agent present in the toner particles exist in a state where they do not contact each other. **Claim 3** The toner for electrostatic charge image development according to claim 1 or claim 2, wherein when observing a cross-section of the toner particles, the toner particles satisfy the following condition (C1). Condition (C1): The domain of the crystalline resin is needle-shaped or plate-shaped, and the domain of the release agent is circular. **Claim 4** The toner for electrostatic charge image development according to claim 1 or claim 2, wherein when observing a cross-section of the toner particles, the toner particles satisfy the following condition (C2). Condition (C2): The domain of the crystalline resin is circular, and the domain of the release agent is needle-shaped or plate-shaped. **Claim 5** The toner for electrostatic charge image development according to claim 3 or claim 4, wherein the aspect ratio of the needle-shaped or plate-shaped domain is 5 or more and 40 or less, and the circularity of the circular domain is 0.92 or more and 1.

00. **Claim 6** The toner for electrostatic charge image development according to any one of claims 1 to 5, wherein the melting temperature of the release agent is 65°C or more and 95°C or less. **Claim 7** The toner for electrostatic charge image development according to claim 6, wherein the release agent having a melting temperature of 65°C or higher and 95°C or lower is an ester wax.

8. The toner for electrostatic charge image development according to any one of claims 1 to 7, wherein the content of the toner particles is 70% by number or more based on all the toner particles.

9. An electrostatic charge image developer containing the toner for electrostatic charge image development according to any one of claims 1 to 8.

10. A toner cartridge that houses the toner for electrostatic charge image development according to any one of claims 1 to 8, and is detachable from an image forming apparatus.

11. A process cartridge that houses the electrostatic charge image developer according to claim 9 and includes developing means for developing an electrostatic charge image formed on the surface of an image carrier as a toner image with the electrostatic charge image developer, and is detachable from an image forming apparatus.

12. An image carrier, charging means for charging the surface of the image carrier, electrostatic charge image forming means for forming an electrostatic charge image on the charged surface of the image carrier, developing means for developing an electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to claim 9, transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, fixing means for fixing the toner image transferred to the surface of the recording medium, and an image forming apparatus comprising the above.

13. A charging step of charging the surface of an image carrier, an electrostatic charge image forming step of forming an electrostatic charge image on the charged surface of the image carrier, a developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to claim 9, a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, a fixing step of fixing the toner image transferred to the surface of the recording medium, and an image forming method having the above.

Images