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

Abstract

To provide an electrostatic charge image development toner which offers high fine-line reproducibility.SOLUTION: An electrostatic charge image development toner provided herein comprises toner particles comprising core particles comprising large particles with a number-average particle diameter of 1 μm or greater, and shell layers consisting of two or more resin layers containing an amorphous resin and covering surfaces of the core particles, where an outermost layer of the two or more resin layers is a resin layer formed of the amorphous resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a toner for developing electrostatic images, a method for producing a toner for developing electrostatic images, an electrostatic image developer, a toner cartridge, a process cartridge, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses an electrostatic latent image developing toner including a plurality of toner particles each having a core containing a binder resin and a release agent and a multilayered shell layer partially covering the surface of the core, wherein the multilayered shell layer includes a first shell layer containing a first polymer containing a repeating unit having an oxazoline group, a second shell layer containing a second polymer containing a repeating unit having a carboxyl group, and a third shell layer containing a third polymer containing a repeating unit having an oxazoline group, and the first, second, and third shell layers have a laminated structure in which, from the core side, the first shell layer, the second shell layer, and the third shell layer are laminated in this order, and the second shell layer is in contact with a surface region of the core that is not covered by the first shell layer.

[0003] Patent Document 2 discloses a toner for developing electrostatic images, which comprises toner particles having a multilayer structure in which an intermediate layer is formed on the surface of a core particle and a shell layer is laminated on this intermediate layer, and the core particles are formed by dispersing a crystalline polyester resin as a domain phase in a matrix phase made of a vinyl polymer A, the average diameter of the domain phase being 300 nm or less, the intermediate layer containing a vinyl polymer B, and the shell layer containing an amorphous resin in which a vinyl polymer segment and a polyester polymer segment are chemically bonded.

[0004] Patent Document 3 discloses a toner for developing electrostatic latent images having a core-shell structure in which core particles containing at least a resin and a colorant are coated with a shell layer, the shell layer being free of wax, and the difference (ΔSP) between the solubility parameter values ​​(SP values) of the core particle and the shell layer being 0.2 to 0.7. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-097052 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-206610 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-163026 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been an increasing demand for anti-counterfeiting technology, such as printing using "special colors" on coupons, discount vouchers, certificates, etc., and for creating lines, illustrations, etc. by arranging minute micro-characters that are unreadable to the naked eye. However, when a toner containing large particles such as scaly pigments or large luminescent particles is used as a coloring material for a special color, it is difficult to obtain good electrical properties and powder flowability, and it may be difficult to obtain fine line reproducibility.

[0007] The present invention aims to provide a toner for developing electrostatic images, which contains toner particles having a shell layer and core particles with large diameter particles having a number average particle diameter of 1 μm or more, and which has high fine line reproducibility compared to a toner in which the shell layer consists of only one resin layer or a toner in which the shell layer consists of two or more resin layers and the outermost layer contains a release agent. [Means for solving the problem]

[0008] Specific means for solving the above problems include the following aspects.

[0009] <1> core particles having a number average particle size of 1 μm or more; a shell layer that covers the surface of the core particle and is composed of two or more resin layers containing an amorphous resin, wherein the outermost layer of the two or more resin layers is a resin layer made of the amorphous resin; and A toner for developing electrostatic images, comprising toner particles having the formula: <2> the shell layer is composed of three or more resin layers containing an amorphous resin, the innermost layer of the three or more resin layers is a resin layer made of the amorphous resin, an intermediate layer, which is a layer other than the outermost layer and the innermost layer among the three or more resin layers, containing the amorphous resin and at least one selected from the group consisting of a release agent, a crystalline resin, and a colorant; <1> 2. The toner for developing electrostatic images according to claim 1.

[0010] <3> The large particles include scaly particles. <1> or <2> 2. The toner for developing electrostatic images according to claim 1. <4> The large particles include luminescent particles. <1> or <2> 2. The toner for developing electrostatic images according to claim 1. <5> One of the core particles is composed of one of the large particle. <1> ~ <4> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <6> One core particle contains two or more of the large particles and an amorphous resin. <1> ~ <4> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <7> The content of the large diameter particles relative to the total amount of the core particles is 50% by mass or more. <6> 2. The toner for developing electrostatic images according to claim 1. <8> the toner contains no resin particles alone that contain an amorphous resin but do not contain the large-diameter particles, or the content of the resin particles alone is 80% by number or less of the entire toner for developing electrostatic images; <1> ~ <7> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images.

[0011] <9> a core particle dispersion preparation step of preparing a core particle dispersion in which core particles having a number average particle diameter of 1 μm or more are dispersed; a resin particle layer forming step of adding amorphous resin particles to the core particle dispersion and aggregating the amorphous resin particles so that the amorphous resin particles adhere to the core particles, thereby forming a resin particle layer on the surfaces of the core particles; a repeating step of repeating the above operation one or more times, in which the particles added in the final step are only the amorphous resin particles, thereby forming aggregated particles having two or more resin particle layers on the surface of the core particle, the outermost layer of which is made of the amorphous resin particles; a fusion / coalescence step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles; A method for producing a toner for developing electrostatic images, comprising: <10> the particles added in the resin particle layer forming step are the amorphous resin particles alone, The repeating step is a step of repeating the above operation two or more times, and the particles added in one or more of the operations excluding the last one contain the amorphous resin particles and at least one particle selected from the group consisting of release agent particles, crystalline resin particles, and colorant particles, thereby forming aggregated particles having three or more resin particle layers on the surface of the core particle, the innermost layer of the three or more resin particle layers being made of the amorphous resin particles, and an intermediate layer, which is a layer other than the outermost and innermost layers of the three or more resin particle layers, containing the amorphous resin particles and at least one particle selected from the group consisting of the release agent particles, the crystalline resin particles, and the colorant particles. <9> 10. A method for producing the toner for developing electrostatic images according to claim 9.

[0012] <11> The large-diameter particles include at least one type selected from the group consisting of scale-like particles and luminescent particles. <9> or <10> 10. A method for producing the toner for developing electrostatic images according to claim 9. <12> One of the core particles is composed of one of the large particle. <9> ~ <11> 10. A method for producing the toner for developing electrostatic images according to any one of claims 1 to 9. <13> One core particle contains two or more of the large particles and an amorphous resin. <9> ~ <12> 10. A method for producing the toner for developing electrostatic images according to any one of claims 1 to 9. <14> The content of the large diameter particles relative to the total amount of the core particles is 50% by mass or more. <13> 10. A method for producing the toner for developing electrostatic images according to claim 9.

[0013] <15> In all operations of the resin particle layer forming step and the repeating step, an aggregating agent is added to the core particle dispersion in addition to the amorphous resin particles. <9> ~ <14> 10. The method for producing the toner for developing electrostatic images according to claim 9. <16> the aggregation temperature in each operation of the repeating step is higher than the aggregation temperature in the immediately preceding operation; <9> ~ <15> 10. A method for producing the toner for developing electrostatic images according to any one of claims 1 to 9. <17> the amount of the amorphous resin particles added in each operation of the repeating step is greater than the amount of the amorphous resin particles added in the operation immediately before the operation; <9> ~ <16> 10. A method for producing the toner for developing electrostatic images according to any one of claims 1 to 9.

[0014] <18> <9> ~ <17> 10. A toner for developing electrostatic images, which is obtained by the method for producing a toner for developing electrostatic images according to any one of 1 to 8.

[0015] <19> <1> ~ <8> and <18> 10. An electrostatic image developer comprising the toner for developing electrostatic images according to any one of claims 1 to 9. <20> <1> ~ <8> and <18> The toner for developing electrostatic images according to any one of the above items is contained, A toner cartridge that is detachably attached to an image forming device. <21> <19> and a developing means for developing an electrostatic image formed on the surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge is detachably mounted in an image forming apparatus. <22> an image carrier; a charging means for charging the surface of the image carrier; an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; <19> a developing means for developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing means for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising: [Effects of the Invention]

[0016] <1> According to the invention, there is provided a toner for developing electrostatic images, which includes toner particles having a shell layer and core particles which are large particles having a number average particle size of 1 μm or more, and which has high fine line reproducibility compared to a case where the shell layer is made of only one resin layer or a case where the shell layer is made of two or more resin layers and the outermost layer contains a release agent. <2> According to the invention related to (1), a toner for developing electrostatic images is provided which has high fine line reproducibility compared to when the innermost layer contains a release agent.

[0017] <3> According to the invention, even if the large-diameter particles contain scaly particles, an electrostatic image developing toner having high fine line reproducibility is provided compared to a case in which the shell layer is made of only one resin layer or a case in which the shell layer is made of two or more resin layers and the outermost layer contains a release agent. <4> According to the invention, even if the large diameter particles contain luminescent particles, a toner for developing electrostatic images is provided which has high fine line reproducibility compared to a case where the shell layer consists of only one resin layer or a case where the shell layer consists of two or more resin layers and the outermost layer contains a release agent. <5> According to the invention, a toner for developing electrostatic images is provided in which the function of the large diameter particles is more easily exhibited than when one core particle contains two or more large diameter particles and an amorphous resin. <6> According to the invention, there is provided a toner for developing electrostatic images which has good smoothness of a fixed toner image compared to when one core particle is composed of one large particle. <7> According to the invention, there is provided a toner for developing electrostatic images in which the functions of the large diameter particles are more easily exhibited than when the content of the large diameter particles is less than 50% by mass. <8> According to the invention, there is provided a toner for developing electrostatic images that can provide fixed images with good graininess compared to when the content of resin particles alone exceeds 80% by number.

[0018] <9> , <11> , <12> , <13> , or <14> According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which does not have a repeating process and can produce a toner for developing electrostatic images with high fine line reproducibility compared to a case in which a resin particle layer is formed only once. <10> According to the invention, there is provided a method for producing a toner for developing electrostatic images, which can produce a toner for developing electrostatic images with high fine line reproducibility compared to when the innermost layer of the resin particle layer contains a release agent. <15> According to the invention, there is provided a method for producing a toner for developing electrostatic images, which can produce a toner for developing electrostatic images with high fine line reproducibility compared to when a coagulant is not added in the repeating steps. <16> According to the invention related to (1), there is provided a method for producing a toner for developing electrostatic images, which can produce a toner for developing electrostatic images with high fine line reproducibility compared to when the aggregation temperature in the repeated step is equal to or lower than the aggregation temperature in the immediately preceding operation. <17> According to the invention related to the above, there is provided a method for producing a toner for developing electrostatic images, which can produce a toner for developing electrostatic images with excellent thin line reproducibility, compared to a case where the amount of amorphous resin particles added in the repeated step is equal to or less than the amount of amorphous resin particles added in the immediately preceding operation.

[0019] <18> According to the invention, there is provided a toner for developing electrostatic images that has high fine line reproducibility compared to a case where a resin particle layer is formed only once without using a repeating process.

[0020] <19> , <20> , <21> , or <22> According to the invention, there is provided an electrostatic image developer, a toner cartridge, a process cartridge, or an image forming apparatus, which includes a toner for developing electrostatic images that has high fine line reproducibility compared to a toner containing toner particles having a shell layer and core particles with large diameter particles having a number average particle diameter of 1 μm or more, wherein the shell layer consists of only one resin layer, or a shell layer consisting of two or more resin layers with the outermost layer containing a release agent, or a case where a resin particle layer is formed only once without a repeating process. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of a process cartridge according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described. These descriptions and examples are intended to illustrate the embodiment and are not intended to limit the scope of the invention. In the present specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range. In addition, in the present specification, the upper or lower limit of a numerical range may be replaced with a value shown in the examples.

[0023] Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0024] [Electrostatic image developing toner] The electrostatic image developing toner according to this embodiment (hereinafter, the electrostatic image developing toner may be referred to as "toner") includes toner particles having core particles with large diameter particles (hereinafter, sometimes simply referred to as "large diameter particles") having a number average particle diameter of 1 μm or more, and a shell layer that comprises two or more resin layers containing an amorphous resin and covers the surface of the core particle. The shell layer includes a resin layer made of an amorphous resin as the outermost layer of the two or more resin layers. The toner according to the present embodiment has the above-described structure, and therefore exhibits high thin line reproducibility. The reason for this is presumed to be as follows.

[0025] When a resin layer is formed by adhering amorphous resin particles to core particles having large diameter particles with a number average particle size of 1 μm or more, it may be difficult for the amorphous resin particles to adhere to the surfaces of the core particles. In particular, when the core particles have large diameters, it is necessary to attach a larger amount of resin than when the core particles do not have large diameters. Therefore, for example, when amorphous resin particles are added to a dispersion of core particles, the addition of a large amount of amorphous resin particles increases the concentration of amorphous resin particles in the dispersion, making the amorphous resin particles more likely to aggregate. This can result in the formation of resin-only particles that do not contain core particles, and toner particles in which the surfaces of the core particles are not completely covered with the resin layer and are exposed. Toner particles with exposed core particle surfaces have low chargeability, so if the coverage rate of the resin layer on the core particle surface varies, the charge distribution will become wider, causing toner scattering and resulting in poor fine line reproducibility (e.g., microcharacter distortion).

[0026] In contrast to this, in this embodiment, a shell layer made up of two or more resin layers is provided, and the outermost layer of the shell layer is made of an amorphous resin. In other words, the toner particles in this embodiment are obtained by coating core particles with a resin layer through two or more steps. For example, when a resin layer is formed on the surface of core particles by adding amorphous resin particles to a dispersion of core particles, the concentration of amorphous resin particles in the dispersion is lower by two or more steps than when a resin layer of the same mass is formed on the surface of core particles in a single step. Therefore, it is thought that adhesion of amorphous resin particles to the surface of core particles is more likely to occur than aggregation of amorphous resin particles, thereby suppressing the formation of resin particles alone and increasing the coverage of the resin layer on the surface of core particles. Furthermore, a high coverage of the resin layer on the surface of core particles suppresses a decrease in chargeability due to exposed core particle surfaces, thereby improving fine line reproducibility.

[0027] On the other hand, even in the case of a shell layer composed of two or more resin layers, if the outermost shell layer contains a release agent, aggregation of toner particles occurs, broadening the particle size distribution and causing variations in electrical properties, which may result in a decrease in fine line reproducibility. Similarly, if the outermost shell layer contains a crystalline resin, aggregation of toner particles may also result in a decrease in fine line reproducibility. In contrast, in this embodiment, the toner has a shell layer made up of two or more resin layers, and the outermost layer of the shell layer is made of an amorphous resin, which is thought to suppress the deterioration of fine line reproducibility caused by the aggregation of toner particles. For the above reasons, it is presumed that the toner according to this embodiment has high thin line reproducibility.

[0028] The toner according to this embodiment will be described in detail below.

[0029] The toner according to this embodiment contains toner particles and, if necessary, an external additive.

[0030] <Toner particles> The toner particles have a core particle having a large particle diameter with a number average particle diameter of 1 μm or more, and a shell layer made of two or more resin layers that covers the surface of the core particle.

[0031] (core particle) The core particle may include, for example, a core particle consisting of a single large particle (hereinafter also referred to as a "single core particle"), a core particle containing two or more large particles and an amorphous resin (hereinafter also referred to as a "composite core particle"), and the like.

[0032] -Single core particle- One single core particle consists of one large particle. When a single core particle is used as the core particle, the function of a large particle is more easily exhibited than when a composite core particle is used. For example, when a luster pigment described below is used as the large particle, using a single core particle as the core particle makes it easier to obtain an image with high luster. Specifically, when one core particle contains two or more luster pigments, the luster of the obtained image may decrease due to the orientation planes of the two or more luster pigments being different from each other, but using a single core particle makes it easier to suppress the decrease in luster.

[0033] -Composite core particle- The composite core particle is not limited as long as it contains two or more large particles and an amorphous resin. The use of composite core particles as core particles has the advantage of improving the smoothness of the toner fixed image compared to the use of single core particles. Although the reason for this is unclear, it is presumed that the composite core particles have a relatively small size per large particle compared to the size of the toner particle, and the core particles themselves contain an amorphous resin, which makes it difficult for surface irregularities to occur during fixing. The number of large-diameter particles contained in the composite core particle is 2 or more, and can be in the range of 2 to 10. From the viewpoint of achieving both low-temperature fixability and image bending strength, the number is preferably in the range of 3 to 8, and more preferably in the range of 3 to 6.

[0034] The content of the large particles relative to the total composite core particles is preferably 50% by mass or more, more preferably 50% by mass to 90% by mass, and even more preferably 50% by mass to 70% by mass. When the content of the large particles is within the above range, the functions of the large particles are more easily exhibited than when the content is less than the above range. For example, when a glitter pigment, as described below, is used as the large particles, when the content of the large particles is within the above range, images with high glitter are more easily obtained. Furthermore, when the content of the large particles is within the above range, deterioration of charging characteristics due to exposure of the large particles due to loads such as stirring in the developing unit is suppressed, compared to when the content is greater than the above range, resulting in better charge retention.

[0035] The composite core particle may contain other components in addition to the large particle and the amorphous resin, as necessary, such as a release agent, a crystalline resin, a colorant, and other additives. In addition to the large-diameter particle and the amorphous resin, the composite core particle preferably contains at least one selected from the group consisting of a release agent, a crystalline resin, and a colorant, more preferably at least one selected from the group consisting of a release agent and a crystalline resin, and even more preferably contains a release agent.

[0036] When composite core particles containing a releasing agent are used as core particles, the toner can more easily achieve low-temperature fixability compared to when no releasing agent is contained. When the composite core particles contain a release agent, the content of the release agent relative to the entire composite core particle is, for example, in the range of 2% by mass or more and 20% by mass or less, and from the viewpoint of low-temperature fixability and suppression of release agent offset (i.e., suppression of part of the release agent remaining on the fixing belt due to too much release agent), it is preferably in the range of 5% by mass or more and 15% by mass or less.

[0037] Furthermore, when composite core particles containing a crystalline resin are used as core particles, the toner can more easily achieve low-temperature fixability compared to when no crystalline resin is contained. When the composite core particle contains a crystalline resin, the content of the crystalline resin relative to the entire composite core particle is, for example, in the range of 2% by mass to 40% by mass, and from the viewpoint of improving low-temperature fixability and charging properties (for example, suppressing charge leakage due to a large amount of crystalline resin, suppressing environmental differences between high-temperature, high-humidity environments and low-temperature, low-humidity environments), it is preferably in the range of 5% by mass to 25% by mass.

[0038] Furthermore, when composite core particles containing a colorant are used as core particles, a toner having a color closer to the desired color can be more easily obtained than when no colorant is contained. When the composite core particle contains a colorant, the content of the colorant relative to the entire composite core particle is, for example, in the range of 0.05% by mass to 10% by mass. Each component contained in the core particle will be described below.

[0039] -Large particles- Large particles are particles with a number average particle size of 1 μm or more. The number average particle size of the large particles is, for example, in the range of 1 μm or more and 10 μm or less, and from the viewpoint of color characteristics (e.g., brilliance, phosphorescence, etc.) and fine line reproducibility, it is preferably in the range of 2 μm or more and 9 μm or less, and more preferably in the range of 3 μm or more and 8 μm or less.

[0040] The number average particle size of the large particles is a value measured using a Coulter Multisizer II (manufactured by Beckman Coulter) and an ISOTON-II (manufactured by Beckman Coulter) electrolyte. For the measurement, 0.5 mg to 50 mg of the sample to be measured is added to 2 ml of a 5 mass % aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is then added to 100 ml to 150 ml of the electrolyte. The electrolyte solution containing the suspended sample is dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the particle size distribution measured, a cumulative distribution is drawn for each divided particle size range (channel) from the smallest diameter side, and the particle size at which the cumulative 50% is reached is the number-average particle size. The number average particle size of the large particles in the toner may be a value measured by the above method after removing components other than the large particles.

[0041] Specific examples of large-diameter particles include scaly particles such as glittering pigments, and luminescent particles containing luminescent materials. When scaly particles are used as the large particles, toner particles having exposed core particle surfaces are more likely to be obtained than when spherical particles are used as the large particles. However, in this embodiment, the coverage of the resin layer on the core particle surfaces is increased, so that the deterioration of fine line reproducibility caused by the exposed core particle surfaces is suppressed.

[0042] --Scaly particles-- Examples of scaly particles include particles having a ratio of the average length in the major axis direction to the average length in the thickness direction of 1 (hereinafter also referred to as "aspect ratio") of 5 or more, such as glitter pigments. Examples of luster pigments, which are scaly particles, include metal powders such as aluminum (metallic aluminum), brass, bronze, nickel, stainless steel, and zinc; mica coated with titanium oxide, yellow iron oxide, and the like; flaky inorganic crystalline substrates coated with barium sulfate, layered silicates, layered aluminum silicates, and the like; single-crystal plate-like titanium oxide; basic carbonates; bismuth oxychloride; natural guanine; flaky glass powder; and flaky glass powder with metal vapor deposition. Among the bright pigments, metal powders are preferred from the viewpoint of specular reflection intensity, and among these, aluminum is most preferred.

[0043] The average length in the major axis direction of the bright pigment is preferably 1 μm or more and 30 μm or less, more preferably 3 μm or more and 20 μm or less, and even more preferably 5 μm or more and 15 μm or less. The ratio (aspect ratio) of the average length in the major axis direction to the average length in the thickness direction of the luster pigment, which is taken as 1, is preferably 5 or more and 200 or less, more preferably 10 or more and 100 or less, and even more preferably 30 or more and 70 or less.

[0044] The average length and aspect ratio of each of the bright pigment particles are measured by the following method: Using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation), photographs of pigment particles are taken at a measurable magnification (300 to 100,000 times), and the resulting images of the pigment particles are converted into two-dimensional images, and the length in the major axis direction and the length in the thickness direction of each particle are measured to calculate the average length in the major axis direction and the aspect ratio of the bright pigment.

[0045] --Luminous particles-- The luminescent particles include particles that absorb irradiated light and emit light. The luminescent particles are particles containing a luminescent material that absorbs irradiated light and emits light, and may be particles made of the luminescent material or particles in which the luminescent material is dispersed in a resin or the like. Examples of the light-emitting material include fluorescent materials that emit the energy of absorbed light as fluorescence, and phosphorescent materials that store the energy of absorbed light inside and emit it as phosphorescence in the dark.

[0046] The fluorescent material may be an inorganic fluorescent material or an organic fluorescent material. Examples of inorganic fluorescent materials include those that contain crystals of oxides, sulfides, silicates, phosphates, tungstates, etc. of Ca, Ba, Mg, Zn, Cd, etc. as the main component, to which metal elements such as Mn, Zn, Ag, Cu, Sb, Pb, etc. or rare earth elements such as lanthanoids are added as an activator and then fired. Examples of organic fluorescent materials include fluorescent brighteners, derivatives of diaminostilbene, imidazole, coumarin, triazole, carbazole, pyridine, naphthalic acid, imidazolone, and the like, fluorescein, mineral oil, thioflavin, eosin, todamine, anthracene, terphenyl, brilliant sulfotravine, basic yellow, eolen, and organic pigment dyes (trade names: Lumorgen Color (BASF), FZ6014 (Shin-Roi-Chino)).

[0047] Examples of phosphorescent materials include inorganic pigments such as zinc sulfide (ZnS), zinc silicate (Zn2SiO4), zinc cadmium sulfide [(Zn,Cd)S], calcium sulfide (CaS), strontium sulfide (SrS), calcium tungstate (CaWO4), strontium aluminate (SrAl2O4), phosphorescent zinc sulfide, and zinc hexasulfide, as well as organic pigments such as Lumogen L Yellow, Lumogen Yellow Orange, and Lumogen L Red Orange. Rare earth elements, particularly Eu and Dy, may also be added to the inorganic pigments.

[0048] The fluorescent material and the phosphorescent material may be surface-treated with a surface treatment agent for the purpose of improving dispersibility in the resin. As the surface treatment agent, various known surface treatment agents such as coupling agents or dispersibility improvers can be used, and specific examples of the surface treatment agent include silane-based coupling agents, titanate-based coupling agents, aluminate-based coupling agents, and zirconate-based coupling agents.

[0049] Examples of resins in which the light-emitting material can be dispersed include polyvinyl resins such as polyolefin, polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, vinyl chloride, and polyvinyl butyral; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of organosiloxane bonds and modified versions thereof; fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, and polyvinylidene fluoride; polyester, polyurethane, polycarbonate; amino resin; and epoxy resin. These resins may be used alone or in combination. These resins may be crosslinked. Further, examples of the resin in which the light-emitting material is dispersed include the amorphous resin used in the toner of this embodiment, which will be described later.

[0050] When the luminescent particles are particles in which a luminescent material is dispersed in a resin, the content of the luminescent material relative to the entire luminescent particles is, for example, in the range of 5% by mass or more and 40% by mass or less, and may also be in the range of 10% by mass or more and 20% by mass or less. The luminescent particles may be particles in which a fluorescent material is dispersed in a resin, particles in which a phosphorescent material is dispersed in a resin, or particles in which both a fluorescent material and a phosphorescent material are dispersed in a resin.

[0051] -Amorphous resin- Examples of amorphous resins include vinyl resins made 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.), and olefins (e.g., ethylene, propylene, butadiene, etc.), or copolymers of two or more of these monomers. Examples of amorphous resins include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin, mixtures of these with the vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These amorphous resins may be used alone or in combination of two or more.

[0052] The "crystalline" nature of a resin refers to the presence of a clear endothermic peak rather than a stepwise change in endothermic heat in differential scanning calorimetry (DSC). Specifically, this refers to the half-width of the endothermic peak being within 10°C when measured at a heating rate of 10°C / min. On the other hand, the term "amorphous" for a resin means that the half-width exceeds 10°C, that the endothermic amount exhibits a stepwise change, or that no clear endothermic peak is observed.

[0053] As the amorphous resin, a polyester resin is preferable. Examples of the amorphous polyester resin include a condensation polymer of a polycarboxylic acid and a polyhydric alcohol. Note that, as the amorphous polyester resin, a commercially available product or a synthesized product may be used.

[0054] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (such as cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. The polycarboxylic acid may be a trivalent or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acids may be used alone or in combination of two or more.

[0055] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, preferred polyhydric alcohols are aromatic diols and alicyclic diols, and more preferred are aromatic diols. As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more.

[0056] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 65°C or lower. The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, from the "extrapolated glass transition onset temperature" described in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0057] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less. The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less. The molecular weight distribution Mw / Mn of the amorphous polyester 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 number-average molecular weight are measured by gel permeation chromatography (GPC). Molecular weight measurements by GPC are performed using a Tosoh GPC HLC-8120GPC measuring device and a Tosoh TSKgel SuperHM-M (15 cm) column in THF solvent. The weight-average molecular weight and number-average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0058] The amorphous polyester resin can be obtained by a known manufacturing method, for example, by carrying out the reaction at a polymerization temperature of 180°C or higher and 230°C or lower, reducing the pressure in the reaction system as necessary, and removing water and alcohol generated during the condensation. If the raw material monomer is not soluble or compatible at the reaction temperature, a high-boiling solvent may be added as a solubilizer to dissolve it. In this case, the polycondensation reaction is carried out while distilling off the solubilizer. If a monomer with poor compatibility is present, it is advisable to first condense the poorly compatible monomer with the acid or alcohol to be polycondensed, and then polycondense the monomer with the main component.

[0059] -Mold release agent- Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but are not limited thereto.

[0060] The melting temperature of the release agent is preferably 50°C or higher and 110°C or lower, and more preferably 60°C or higher and 100°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" as described in the method for determining the melting temperature in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0061] -Crystalline resin- Examples of the crystalline resin include crystalline polyester resin. The crystalline polyester resin may be, for example, a polycondensate of a polycarboxylic acid and a polyhydric alcohol. Note that, as the crystalline polyester resin, a commercially available product or a synthesized product may be used. Here, the crystalline polyester resin is preferably a polycondensate using a polymerizable monomer having a linear aliphatic group rather than a polymerizable monomer having an aromatic group, since it easily forms a crystalline structure.

[0062] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acid may be a tricarboxylic or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the tricarboxylic 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, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids. The polycarboxylic acids may be used alone or in combination of two or more.

[0063] Examples of polyhydric alcohols include aliphatic diols (for example, straight-chain aliphatic diols having 7 to 20 carbon atoms in the main chain). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols. The polyhydric alcohol may be a trihydric or higher alcohol having a crosslinked or branched structure, such as glycerin, trimethylolethane, trimethylolpropane, or pentaerythritol, in combination with the diol. The polyhydric alcohols may be used alone or in combination of two or more.

[0064] Here, the polyhydric alcohol preferably has an aliphatic diol content of 80 mol % or more, and more preferably 90 mol % or more.

[0065] The melting temperature of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 90°C or lower, and even more preferably 60°C or higher and 85°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121-1987 "Method for measuring transition temperatures of plastics."

[0066] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0067] The crystalline polyester resin can be obtained by a known manufacturing method, for example, in the same manner as the amorphous polyester resin.

[0068] -Coloring agent- Examples of colorants include carbon black, chrome yellow, Hansa Yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Balkan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, ultramarine blue, and the like. Examples of the dye include various pigments such as phosphorus blue, chalco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate, and various 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, and thiazole-based dyes. The colorant may be used alone or in combination of two or more kinds.

[0069] The colorant may be surface-treated as needed, or may be used in combination with a dispersant. Furthermore, a plurality of colorants may be used in combination.

[0070] -Other additives- Examples of other additives include well-known additives such as magnetic materials, charge control agents, inorganic powders, etc. These additives are contained in the composite core particles as internal additives.

[0071] (shell layer) The shell layer is made up of two or more resin layers, and includes a resin layer made of an amorphous resin as the outermost layer of the two or more resin layers. Here, the "outermost layer" is a layer that constitutes the surface of a toner particle, the "innermost layer" is a layer that contacts the core particle, and the "intermediate layer" is a layer other than the outermost layer and the innermost layer. The number of resin layers constituting the shell layer should be at least two or more, for example, in the range of 2 to 20. From the viewpoint of fine line reproducibility and ease of production, it is preferably 3 to 15 or less, and more preferably 3 to 10 or less. When the number of resin layers constituting the shell layer is two, the shell layer is composed of two resin layers arranged in the order of the innermost layer and the outermost layer from the core particle side. When the number of resin layers constituting the shell layer is three, the shell layer is composed of three resin layers arranged in the order of the innermost layer, the intermediate layer, and the outermost layer from the core particle side. When the number of resin layers constituting the shell layer is four, the shell layer is composed of four resin layers arranged in the order of the innermost layer, the first intermediate layer, the second intermediate layer, and the outermost layer from the core particle side.

[0072] Of the two or more resin layers, the outermost layer is a resin layer made of an amorphous resin, while the innermost layer and the intermediate layer contain at least an amorphous resin and may contain a release agent, a crystalline resin, a colorant, other additives, etc., as needed. Specific examples of the amorphous resin, release agent, crystalline resin, and colorant contained in the shell layer are the same as the specific examples of the amorphous resin, release agent, crystalline resin, and colorant described as components contained in the composite core particle. Here, the resin layer made of an amorphous resin is a resin layer to which no release agent, crystalline resin, or release agent, which are toner constituent materials other than the amorphous resin, have been intentionally added, and may contain components (e.g., aggregating agents, dispersion media, etc.) that are inevitably mixed in during the manufacturing process.

[0073] When the core particle contains components other than the large particle, the types of components contained in the shell layer may be the same as or different from the types of components contained in the core particle. Specifically, for example, when the core particle contains an amorphous polyester resin, the amorphous resin contained in the shell layer may be the same resin as the amorphous polyester resin contained in the core particle, may be a different amorphous polyester resin, or may be an amorphous resin other than a polyester resin.

[0074] The resin layers constituting the shell layer may have the same composition or different compositions, but it is preferable that adjacent resin layers constituting the shell layer have different compositions. Here, examples of two resin layers with different compositions include two resin layers that contain different types of components, two resin layers that contain the same types of components but in different ratios, and two resin layers in which some of the components contained in one resin layer are not contained in the other resin layer.

[0075] From the viewpoint of suppressing uneven gloss of the fixed image, the shell layer preferably includes a resin layer containing a release agent. When the number of resin layers constituting the shell layer is two, from the viewpoint of suppressing uneven gloss of the fixed image, it is preferable that the innermost layer contains a release agent. When the number of resin layers constituting the shell layer is three or more, it is preferable that at least one resin layer selected from the innermost layer and the intermediate layer contains a release agent, from the viewpoint of suppressing uneven gloss of the fixed image.

[0076] On the other hand, when the core particles contain a release agent, it is preferable that the innermost layer of the shell layer does not contain a release agent, from the viewpoint of suppressing deterioration of the particle size distribution due to aggregation caused by hydrophobic interactions during the production process. In other words, from the viewpoint of simultaneously suppressing uneven gloss of the fixed image and suppressing deterioration of the particle size distribution, it is preferable that the shell layer contains three or more resin layers, the innermost layer does not contain a release agent, and the intermediate layer contains a resin layer that contains a release agent.

[0077] From the viewpoint of fine line reproducibility, the shell layer preferably comprises three or more resin layers, the innermost layer being made of an amorphous resin, and at least one of the intermediate layers preferably containing an amorphous resin and at least one selected from the group consisting of a release agent, a crystalline resin, and a colorant. By including a resin layer containing at least one selected from the group consisting of a release agent, a crystalline resin, and a colorant as the intermediate layer, electrostatic repulsion is suppressed, and the coverage of the shell layer on the surface of the core particle is likely to be increased.

[0078] From the viewpoint of achieving both improved thermal properties and low-temperature fixability of the toner, the outermost shell layer preferably contains an amorphous resin having a higher glass transition temperature than the amorphous resins contained in the other resin layers. The difference Tg1-Tg2 between the glass transition temperature Tg1 of the amorphous resin contained in the outermost shell layer and the glass transition temperature Tg2 of the amorphous resin contained in the other resin layers is, for example, in the range of 0°C or higher and 15°C or lower. From the viewpoint of achieving both improved thermal properties and low-temperature fixability of the toner, the difference Tg1-Tg2 is preferably in the range of 0°C or higher and 12°C or lower, and more preferably in the range of 0°C or higher and 10°C or lower. Furthermore, the Tg1 may be, for example, in the range of 45°C or higher and 65°C or lower, and from the viewpoint of achieving both improved thermal properties and low-temperature fixability of the toner, the range of 50°C or higher and 63°C or lower is preferred, and the range of 55°C or higher and 61°C or lower is more preferred.

[0079] The mass of the entire shell layer is, for example, in the range of 100 to 450 parts by mass relative to 100 parts by mass of the core particle, preferably in the range of 150 to 400 parts by mass, and more preferably in the range of 200 to 350 parts by mass. Having the mass of the entire shell layer within this range results in a higher coverage of the surface of the core particle with the shell layer and improved fine line reproducibility compared to when the mass of the entire shell layer is less than this range. Furthermore, having the mass of the entire shell layer within this range has the advantage that the function of the large-diameter particles is more easily exhibited compared to when the mass of the entire shell layer is greater than this range. In this embodiment, since the core particle contains large-diameter particles, it is preferable to make the overall mass larger than that of a shell layer that covers a core particle that does not contain large-diameter particles.

[0080] The thickness of the entire shell layer can be, for example, in the range of 0.5 μm to 4 μm, preferably in the range of 0.8 μm to 3 μm, and more preferably in the range of 1.2 μm to 2.5 μm. Having the thickness of the entire shell layer within this range improves fine line reproducibility compared to when the thickness is smaller than this range. In addition, having the thickness of the entire shell layer within this range has the advantage that the function of the large-diameter particles is more easily exhibited compared to when the thickness is larger than this range. The thickness of the entire shell layer is determined by observing the cross section of the toner using STEM and calculating the distance from the toner surface to the pigment. For example, in a glitter toner using a glitter pigment as the large particle, the thickness of the entire shell layer is measured as follows. Specifically, the glitter toner is embedded in a bisphenol A liquid epoxy resin and a curing agent, and then a cutting sample is prepared. The cutting sample is then cut at -100°C using a diamond knife cutting machine (e.g., a LEICA Ultramicrotome (manufactured by Hitachi Technologies)) to prepare an observation sample. The cross section of this observation sample is observed under a transmission electron microscope (TEM) at a magnification of approximately 5000x. For the 1000 glitter toner particles observed, the distance between the toner surface and the large particles in the cross section of the glitter toner particle is calculated using image analysis software.

[0081] (Characteristics of toner particles, etc.) The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 12 μm or less, and more preferably 4 μm or more and 11 μm or less.

[0082] The various average particle sizes and particle size distribution indices of the toner particles are measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For the measurement, 0.5 mg to 50 mg of the sample to be measured is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is then added to 100 ml to 150 ml of the electrolyte. The electrolyte solution containing the suspended sample is dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the particle size distribution measured, cumulative distributions of volume and number are drawn for each divided particle size range (channel) from the smallest diameter side, and the particle size at 16% of the cumulative total is defined as the volume particle size D16v, the number particle size D16p, the particle size at 50% of the cumulative total as the volume average particle size D50v, the cumulative number average particle size D50p, and the particle size at 84% of the cumulative total as the volume particle size D84v and the number particle size D84p. Using these, the volumetric particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 , the number particle size distribution index (GSDp) is (D84p / D16p) 1 / 2 It is calculated as:

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

[0084] The surfaces of inorganic particles as external additives are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is usually, for example, 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the inorganic particles.

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

[0086] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less, based on the toner particles.

[0087] <Resin single particles> The toner of this embodiment preferably does not contain resin particles alone, or the content of resin particles alone is 80% by number or less of the total toner. Resin particles alone are particles that contain an amorphous resin and do not contain large particles. Resin particles alone are formed by aggregation of amorphous resin particles during the process of coating the surface of a core particle with a resin layer. By keeping the content of the resin particles within the above range, compared to when the content is greater than the above range, the occurrence of regions in the fixed image where the function of the large-diameter particles is not exhibited due to the presence of the resin particles alone, which would otherwise cause a decrease in granularity, is suppressed, and a fixed image with good granularity is obtained.Furthermore, by keeping the content of the resin particles within the above range, compared to when the content is greater than the above range, toner particles with a high resin layer coverage relative to the surface of the core particles are more likely to be obtained, and fine line reproducibility is improved.

[0088] The resin particles alone more preferably account for 50% by number or less of the total toner, even more preferably 40% by number or less, and it is particularly preferable that the toner is free of resin particles. The content of resin particles alone is measured as follows. Specifically, toner particles are first embedded using a bisphenol A liquid epoxy resin and a curing agent, and then a cutting sample is prepared. Next, the cutting sample is cut at -100°C using a cutting machine with a diamond knife, such as a LEICA Ultramicrotome (manufactured by Hitachi Technologies), to prepare a sample for observation. The observation sample is observed using a TEM at a magnification of around 5000x. Large particles can be distinguished from the difference in density of the observed image due to the difference in composition with the binder resin. In this manner, the cross sections of 5,000 toner particles are observed, and the proportion of the number of toner particles that do not contain large-diameter particles is calculated.

[0089] <Toner manufacturing method> Next, a method for producing the toner according to this embodiment will be described. The toner according to this exemplary embodiment is obtained by producing toner particles and then externally adding an external additive to the toner particles.

[0090] Toner particles can be obtained by coating core particles with a shell layer. Specifically, the toner particles are obtained through the following steps: a core particle dispersion preparation step of preparing a core particle dispersion in which core particles having large diameter particles with a number-average particle diameter of 1 μm or more are dispersed; a resin particle layer formation step of adding amorphous resin particles to the core particle dispersion and aggregating the amorphous resin particles so that the amorphous resin particles adhere to the core particles, thereby forming a resin particle layer on the surface of the core particles; a repetition step of repeating the above step one or more times, whereby the particles added in the final step are only the amorphous resin particles, thereby forming aggregated particles having two or more resin particle layers on the surface of the core particles, the outermost layer of which is made of the amorphous resin particles; and a fusion and coalescence step of heating the aggregated particle dispersion in which the aggregated particles are dispersed, thereby fusing and coalescing the aggregated particles to form toner particles.

[0091] By obtaining toner particles by the above method, a toner can be produced that can produce images with high fine line reproducibility compared to when toner particles are obtained by forming a resin particle layer only once without going through the above repeated steps. Specifically, as described above, when the core particles have large diameter particles, it is required to attach a large amount of resin, so the concentration of amorphous resin particles in the dispersion of the core particles becomes high, and the amorphous resin particles tend to aggregate with each other. As described above, when resin particles alone are easily formed and many toner particles with exposed core particle surfaces are formed, fine line reproducibility tends to decrease, and the formation of many resin particles alone tends to deteriorate granularity.

[0092] In contrast, in the above-mentioned production method, the shell layer is formed through a resin particle layer forming step and a repeating step. In other words, because the shell layer is coated on the surface of the core particles through two or more steps, the concentration of amorphous resin particles in the dispersion is lower than when a resin layer of the same mass is formed on the surface of the core particles in a single step. Therefore, adhesion of the amorphous resin particles to the surface of the core particles is more likely to occur than aggregation of the amorphous resin particles themselves, which is thought to suppress the formation of particles made of resin alone, increase the coverage of the resin layer on the surface of the core particles, and suppress deterioration of fine line reproducibility and graininess.

[0093] Furthermore, in the repeating process, since the particles added in the final operation are only amorphous resin particles, the outermost layer of the shell layer is a resin layer made of amorphous resin without containing a release agent or the like, and it is thought that a toner can be obtained in which the deterioration of fine line reproducibility due to aggregation of toner particles is suppressed.

[0094] In the resin particle layer forming step and the repeating step, it is preferred that the particles added in the resin particle layer forming step are only amorphous resin particles, and that the repeating step is a step of repeating the above operation two or more times, and that the particles added in one or more of the operations in the repeating step except for the last one contain amorphous resin particles and at least one particle selected from the group consisting of release agent particles, crystalline resin particles, and colorant particles, thereby forming aggregated particles having three or more resin particle layers on the surface of a core particle, the innermost layer of the three or more resin particle layers being made of amorphous resin particles, and the intermediate layer of the three or more resin particle layers being made of amorphous resin particles and at least one particle selected from the group consisting of release agent particles, crystalline resin particles, and colorant particles.

[0095] By undergoing the resin particle layer forming step and the repeating step, a toner is obtained in which the shell layer is made of three or more resin layers containing an amorphous resin, the innermost layer of the three or more resin layers is made of an amorphous resin, and the intermediate layer of the three or more resin layers is made of a resin layer containing an amorphous resin and at least one selected from the group consisting of a release agent, a crystalline resin, and a colorant.

[0096] The amorphous resin particles may be added by adding an amorphous resin particle dispersion in which the amorphous resin particles are dispersed. Details of the amorphous resin particle dispersion are the same as those of the amorphous resin particle dispersion used in the production of composite core particles, which will be described later. Each step will be described below.

[0097] (Core particle dispersion preparation process) -Preparation of single core particle dispersion- When the core particles are single-core particles, the single-core particle dispersion is prepared, for example, by dispersing the single-core particles in a dispersion medium using a surfactant. The dispersion medium, surfactant, dispersion method, and content of core particles used in the preparation of the single-core particle dispersion are the same as the dispersion medium, surfactant, dispersion method, and content of amorphous resin particles used in the preparation of the amorphous resin particle dispersion described below.

[0098] -Preparation of composite core particle dispersion- When the core particles are composite core particles, the composite core particles may be produced by either a dry production method (e.g., a kneading and grinding method) or a wet production method (e.g., an aggregation-coalescence method, a suspension polymerization method, a dissolution-suspension method, etc.) There are no particular limitations on the production method for the composite core particles, and well-known production methods may be used. Among these, it is preferable to obtain composite core particles by the aggregation and coalescence method.

[0099] Specifically, for example, when the composite core particles are produced by the aggregation-coalescence method, The composite core particle dispersion is obtained by manufacturing composite core particles through a step of preparing an amorphous resin particle dispersion in which amorphous resin particles are dispersed (amorphous resin particle dispersion preparation step), and a step of aggregating the amorphous resin particles (and other particles, if necessary) in the amorphous resin particle dispersion (in a dispersion after mixing other particle dispersions, if necessary) to form composite core aggregated particles (aggregation step).

[0100] The composite core particles may be obtained by, in addition to the amorphous resin particle dispersion preparation step and the aggregation step, a step of heating the composite core aggregate particle dispersion in which the composite core aggregate particles are dispersed to fuse and coalesce the composite core aggregate particles. Details of the above-mentioned step of fusing and coalescing the composite core aggregate particles are the same as those of the fusion and coalescence step described below. Furthermore, the composite core particle dispersion may be a dispersion of composite core particles obtained in the process of producing the composite core particles, or a composite core particle dispersion obtained by obtaining composite core particles in a dry state and then dispersing them in a dispersion medium.

[0101] Each step will be described in detail below. In the following description, a method for obtaining composite core particles containing a colorant and a release agent will be described, but the colorant and the release agent are used as needed. Of course, other additives, such as a crystalline resin, may also be used in addition to the colorant and the release agent.

[0102] --Amorphous resin particle dispersion preparation process-- First, an amorphous resin particle dispersion liquid in which amorphous resin particles are dispersed, as well as, 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 amorphous resin particle dispersion liquid is prepared, for example, by dispersing amorphous resin particles in a dispersion medium using a surfactant.

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

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

[0106] In the amorphous resin particle dispersion, examples of a method for dispersing the amorphous resin particles in a dispersion medium include general dispersion methods using a rotary shear homogenizer, a ball mill with media, a sand mill, a dyno mill, etc. Depending on the type of amorphous resin particles, the amorphous resin particles may be dispersed in the amorphous resin particle dispersion using, for example, a phase inversion emulsification method. The phase inversion emulsification method involves dissolving the resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, adding a base to the organic continuous phase (O phase) to neutralize it, and then adding an aqueous medium (W phase), thereby converting the resin from W / O to O / W (so-called phase inversion) and forming a discontinuous phase, and dispersing the resin in particulate form in the aqueous medium.

[0107] The volume average particle size of the amorphous resin particles dispersed in the amorphous resin particle dispersion is, for example, preferably from 0.01 μm to 1 μm, more preferably from 0.08 μm to 0.8 μm, and even more preferably from 0.1 μm to 0.6 μm. The volume average particle size of the amorphous resin particles is measured using a particle size distribution obtained by measurement using a laser diffraction particle size distribution analyzer (e.g., LA-700 manufactured by Horiba, Ltd.), and the cumulative distribution for the volume of the divided particle size range (channel) is calculated from the smallest particle size side, and the particle size at which the cumulative distribution of all particles is 50% is defined as the volume average particle size D50v. The volume average particle sizes of particles in other dispersions are also measured in the same manner.

[0108] The content of the amorphous resin particles in the amorphous resin particle dispersion is, for example, preferably 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] Note that, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared in the same manner as the amorphous resin particle dispersion. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the amorphous resin particle dispersion are the same for the colorant particles dispersed in the colorant particle dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0110] --Agglomeration process-- Next, the colorant particle dispersion and the release agent particle dispersion are mixed together with the amorphous resin particle dispersion. Then, in the mixed dispersion, the amorphous resin particles, the colorant particles, and the release agent particles are hetero-aggregated to form composite core aggregate particles containing the amorphous resin particles, the colorant particles, and the release agent particles and having a diameter close to that of the target toner particles.

[0111] Specifically, for example, an aggregating agent is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to an acidic value (for example, a pH of 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. Thereafter, the mixed dispersion is heated to a temperature equal to or higher than the glass transition temperature of the amorphous resin particles (specifically, for example, a temperature equal to or higher than the glass transition temperature of the amorphous resin particles −30° C. and equal to or lower than the glass transition temperature −10° C.), causing the particles dispersed in the mixed dispersion to aggregate, thereby forming composite core aggregated particles. In the aggregation, for example, the above-mentioned aggregating agent may be added to the mixed dispersion at room temperature (e.g., 25°C) while stirring with a rotary shear homogenizer, the pH of the mixed dispersion may be adjusted to an acidic value (e.g., pH 2 or more and 5 or less), and a dispersion stabilizer may be added as necessary, followed by the above-mentioned heating.

[0112] Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. In particular, when a metal complex is used as the flocculant, the amount of surfactant used can be reduced and the charging characteristics can be improved. If necessary, an additive that forms a complex or a similar bond with the metal ions of the flocculant may be used, and a chelating agent is preferably used as this additive.

[0113] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. The chelating agent may be a water-soluble chelating agent, such as hydroxycarboxylic acid (e.g., tartaric acid, citric acid, gluconic acid), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), etc. The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, per 100 parts by mass of the resin particles. Composite core particles are obtained through the above steps.

[0114] (Resin particle layer forming process and repeating process) In the resin particle layer forming step, amorphous resin particles are added to the core particle dispersion and aggregated so that the amorphous resin particles adhere to the core particles, thereby forming a resin particle layer on the surface of the core particles. In the repeating step, the operation of adding amorphous resin particles to the core particle dispersion and aggregating the amorphous resin particles so that they adhere to the core particles is repeated one or more times. Then, in the final operation, only amorphous resin particles are added to the core particle dispersion to obtain aggregated particles. The aggregated particles have two or more resin particle layers on at least the surface of the core particle, and the outermost layer of the two or more resin particle layers is a resin particle layer made of amorphous resin particles.

[0115] The addition of the amorphous resin particles in each operation of the resin particle layer forming step and the repeating step is carried out, for example, by adding an amorphous resin particle dispersion in which the amorphous resin particles are dispersed. The details of the amorphous resin particle dispersion are the same as those of the amorphous resin particle dispersion used in the production of the composite core particles described above.

[0116] When the above operation is an operation for forming a resin particle layer made of amorphous resin particles, that is, when forming a resin layer made of an amorphous resin among the resin layers in the shell layer of the toner particles, for example, the dispersion liquid to be added is made up of only the amorphous resin particle dispersion liquid. Furthermore, when the above operation is an operation for forming a resin particle layer containing release agent particles, that is, when forming a resin layer containing a release agent among the resin layers in the shell layer of the toner particles, for example, a release agent particle dispersion is added in addition to an amorphous resin particle dispersion. Similarly, when the above operation is an operation for forming a resin particle layer containing crystalline resin particles, that is, when forming a resin layer containing a crystalline resin among the resin layers in the shell layer of the toner particles, for example, a crystalline resin particle dispersion is added in addition to an amorphous resin particle dispersion. Furthermore, when the above operation is an operation for forming a resin particle layer containing colorant particles, that is, when forming a resin layer containing a colorant among the resin layers in the shell layer of the toner particles, for example, a colorant particle dispersion is added in addition to the amorphous resin particle dispersion. The details of the release agent particle dispersion, the crystalline resin particle dispersion, and the colorant particle dispersion used in the above-mentioned operations are the same as the details of the release agent particle dispersion, the crystalline resin particle dispersion, and the colorant particle dispersion used in the production of the composite core particles described above.

[0117] The amount of amorphous resin particles added in each operation of the repeating process is preferably greater than the amount of amorphous resin particles added in the immediately preceding operation. Since the area to be covered by the resin particle layer increases toward the outside, the amount of amorphous resin particles required to form a resin particle layer of the same thickness is thought to increase. Therefore, by increasing the amount of amorphous resin particles added, aggregated particles with a high coverage rate by the resin particle layer can be obtained, resulting in a toner with excellent thin-line reproducibility. The rate of increase in the amount of amorphous resin particles added is not particularly limited. For example, when the amount of amorphous resin particles added when forming the innermost layer is A parts by mass and the amount of amorphous resin particles added when forming the outermost layer is B parts by mass, the ratio B / A is preferably greater than 1, more preferably 1.2 or more and 10 or less, and even more preferably 1.5 or more and 8 or less.

[0118] In the above operation, amorphous resin particles are added to a core particle dispersion, and then the core particles and the amorphous resin particles are hetero-aggregated in the core particle dispersion to which the amorphous resin particle dispersion has been added, thereby forming a resin particle layer on the surface of the core particles. Specifically, for example, an aggregating agent is added to a core particle dispersion to which an amorphous resin particle dispersion has been added, and the pH of the dispersion is adjusted to an acidic value (for example, a pH of 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. After that, the dispersion is heated to a temperature (hereinafter also referred to as the "aggregation temperature") that is equal to or higher than the glass transition temperature of the amorphous resin particles (specifically, for example, a temperature that is equal to or higher than the glass transition temperature of the amorphous resin particles -30°C and equal to or lower than the glass transition temperature -10°C), causing the particles dispersed in the dispersion to aggregate and forming a resin particle layer on the surface of the core particles. In the resin particle layer formation process, for example, the core particle dispersion to which the amorphous resin particle dispersion has been added may be stirred with a rotary shear homogenizer, and the above-mentioned aggregating agent may be added at room temperature (e.g., 25°C), the pH of the mixed dispersion may be adjusted to an acidic value (e.g., a pH of 2 or more and 5 or less), and a dispersion stabilizer may be added as necessary, followed by the heating.

[0119] Details of the flocculant used in the resin particle layer forming step and the additives that may be used as needed are the same as those of the flocculant and additives used in the aggregating step in the production of the composite core particles described above.

[0120] In all operations of the resin particle layer forming step and the repeating step, it is preferable to add an aggregating agent to the core particle dispersion in addition to the amorphous resin particles. For example, in the repeating step, if the core particle dispersion to which the amorphous resin particle dispersion has been added already contains an aggregating agent, the resin particle layer may be formed without adding an aggregating agent. On the other hand, by adding an aggregating agent in the resin particle layer forming step and all operations in the repeating step, an appropriate aggregating agent concentration is maintained throughout all operations, and the coverage rate by the resin particle layer is likely to be high.

[0121] The aggregation temperature in each operation of the repeating process is preferably higher than the aggregation temperature in the immediately preceding operation. Because the resin particle layer tends to become unstable toward the outer periphery, increasing the aggregation temperature makes it easier to obtain stable aggregated particles in the resin particle layer. The degree of temperature increase of the aggregation temperature is not particularly limited. For example, when the aggregation temperature during formation of the innermost layer is E°C and the aggregation temperature during formation of the outermost layer is F°C, the difference (F°C - E°C) is preferably 2°C or more, more preferably 4°C or more and 15°C or less, and even more preferably 6°C or more and 12°C or less.

[0122] (fusion / unification process) Next, the aggregated particle dispersion liquid in which the aggregated particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the amorphous resin particles (for example, a temperature 10 to 30°C higher than the glass transition temperature of the amorphous resin particles), to fuse and coalesce the aggregated particles and form toner particles.

[0123] Through the above steps, toner particles are obtained.

[0124] After the fusion and coalescence process, the toner particles formed in the solution are subjected to a known washing process, a solid-liquid separation process, and a drying process to obtain dry toner particles. In the washing step, it is preferable to carry out sufficient replacement washing with ion-exchanged water from the viewpoint of electrostatic chargeability. Furthermore, the solid-liquid separation step is not particularly limited, but from the viewpoint of productivity, it is preferable to carry out suction filtration, pressure filtration, etc. Furthermore, in the drying step, there is no particular limitation on the method, but from the viewpoint of productivity, it is preferable to carry out freeze drying, flash drying, fluidized drying, vibration-type fluidized drying, etc.

[0125] The toner according to this embodiment is produced by, for example, adding an external additive to the obtained dry toner particles and mixing them. The mixing can be carried out using, for example, a V blender, a Henschel mixer, a Loedige mixer, or the like. Furthermore, if necessary, coarse particles may be removed from the toner using a vibrating sieve, an air sieve, or the like.

[0126] [Electrostatic image developer] The electrostatic image developer according to this embodiment contains at least the toner according to this embodiment. The electrostatic image developer according to this embodiment may be a one-component developer containing only the toner according to this embodiment, or may be a two-component developer containing the toner mixed with a carrier.

[0127] The carrier is not particularly limited, and examples thereof include known carriers, such as coated carriers in which the surface of a core material made of magnetic powder is coated with a coating resin, magnetic powder dispersion carriers in which magnetic powder is dispersed and blended in a matrix resin, and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin. The magnetic powder dispersion type carrier and the resin impregnated type carrier may be a carrier in which the constituent particles of the carrier are used as a core material and are coated with a coating resin.

[0128] Examples of magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0129] Examples of coating resins and matrix resins include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resins containing organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenolic resins, and epoxy resins. The coating resin and the matrix resin may contain other additives such as conductive particles. Examples of conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0130] Here, the method of coating the surface of the core material with a coating resin includes a method of coating with a solution for forming a coating layer in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be selected taking into consideration the coating resin to be used, its applicability, etc. Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer, a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material, a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air, and a kneader coater method in which the core material of the carrier and the solution for forming a coating layer are mixed in a kneader coater and the solvent is removed.

[0131] In the two-component developer, the mixing ratio (mass ratio) of toner to carrier is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0132] [Image forming device / image forming method] An image forming apparatus and an image forming method according to this embodiment will be described. The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the surface of the image carrier, an electrostatic image forming unit that forms an electrostatic image on the surface of the charged image carrier, a developing unit that contains an electrostatic image developer and develops the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic 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. The electrostatic image developer according to the present embodiment is used as the electrostatic image developer.

[0133] The image forming apparatus according to this embodiment carries out an image forming method (the image forming method according to this embodiment) that includes a charging step of charging the surface of an image carrier, an electrostatic image forming step of forming an electrostatic image on the surface of the charged image carrier, a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic 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.

[0134] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as 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 primarily transfers a toner image formed on the surface of an image carrier to the surface of an intermediate transfer medium, and then secondarily transfers the toner image transferred to the surface of the intermediate transfer medium to the surface of a recording medium; an apparatus equipped with a cleaning means that cleans the surface of the image carrier after the transfer of the toner image but before charging; and an apparatus equipped with a discharging means that irradiates the surface of the image carrier with discharging light to discharge it after the transfer of the toner image but before charging. In the case of an intermediate transfer type device, the transfer means is configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means which primarily transfers the toner image formed on the surface of the image carrier onto the surface of the intermediate transfer body, and a secondary transfer means which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of the recording medium.

[0135] In the image forming apparatus according to the present embodiment, for example, a portion including the developing means may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with developing means that accommodates the electrostatic image developer according to the present embodiment is preferably used.

[0136] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. Note that only the main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0137] FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to this embodiment. The image forming apparatus shown in Figure 1 includes first through fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K (image forming means) that output images in the colors yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side horizontally spaced a predetermined distance apart from one another. Note that these units 10Y, 10M, 10C, and 10K may also be process cartridges that are detachable from the image forming apparatus.

[0138] Above each of the units 10Y, 10M, 10C, and 10K in the drawing, an intermediate transfer belt 20 serving as an intermediate transfer body extends through each unit. The intermediate transfer belt 20 is wound around a drive roll 22 and a support roll 24 that are spaced apart from each other and arranged from left to right in the drawing, and is configured to run in a direction from the first unit 10Y to the fourth unit 10K. A force is applied to the support roll 24 in a direction away from the drive roll 22 by a spring or the like (not shown), thereby applying tension to the intermediate transfer belt 20 wound around them. In addition, an intermediate transfer body cleaning device 30 is provided on the image carrier side of the intermediate transfer belt 20, facing the drive roll 22. In addition, the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K are supplied with toner including four colors of toner, yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K, respectively.

[0139] Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, the first unit 10Y, which forms a yellow image and is disposed upstream in the direction of travel of the intermediate transfer belt, will be described here as a representative. Note that parts equivalent to those of the first unit 10Y are given reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y), and descriptions of the second to fourth units 10M, 10C, and 10K will be omitted.

[0140] The first unit 10Y has a photoreceptor 1Y that acts as an image carrier. Around the photoreceptor 1Y, there are arranged in this order: a charging roll (an example of a charging means) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic image forming means) 3 that exposes the charged surface to a laser beam 3Y based on a color-separated image signal to form an electrostatic image; a developing device (an example of a developing means) 4Y that supplies charged toner to the electrostatic image to develop it; a primary transfer roll 5Y (an example of a primary transfer means) that transfers the developed toner image onto an intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer. The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20 and is positioned opposite the photoreceptor 1Y. Furthermore, a bias power supply (not shown) that applies a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power supply varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

[0141] The operation of forming a yellow image in first unit 10Y will be described below. First, prior to operation, the surface of the photosensitive member 1Y is charged to a potential of −600V to −800V by the charging roll 2Y. The photoconductor 1Y has conductivity (for example, volume resistivity at 20°C: 1×10 -6The photosensitive layer is formed by laminating a photosensitive layer on a substrate with a resistivity of Ωcm or less. This photosensitive layer normally has a high resistance (the resistance of ordinary resins), but when irradiated with a laser beam 3Y, the resistivity of the irradiated portion changes. Therefore, a laser beam 3Y is output to the charged surface of the photosensitive element 1Y via an exposure device 3 in accordance with image data for yellow sent from a control unit (not shown). The laser beam 3Y is irradiated onto the photosensitive layer on the surface of the photosensitive element 1Y, thereby forming an electrostatic charge image of a yellow image pattern on the surface of the photosensitive element 1Y.

[0142] An electrostatic image is an image formed on the surface of the photosensitive element 1Y by charging it; the laser beam 3Y reduces the resistivity of the irradiated portion of the photosensitive layer, causing the charged charges on the surface of the photosensitive element 1Y to flow, while the charges remain in the portions not irradiated by the laser beam 3Y, forming a so-called negative latent image. The electrostatic image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic image on the photoreceptor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0143] The developing device 4Y contains an electrostatic image developer containing, for example, at least yellow toner and a carrier. The yellow toner is frictionally charged by being stirred inside the developing device 4Y, and is held on a developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. The photoreceptor 1Y on which the yellow toner image has been formed continues to travel at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0144] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y to the primary transfer roll 5Y acts on the toner image, causing the toner image on the photoreceptor 1Y to be transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the (-) polarity of the toner, and in the first unit 10Y, for example, it is controlled to +10 μA by a control unit (not shown). On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

[0145] Furthermore, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K of the second unit 10M and subsequent units is also controlled in accordance with the first unit. In this way, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is conveyed sequentially through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are transferred onto the intermediate transfer belt 20 in a superimposed manner.

[0146] The intermediate transfer belt 20, onto which the four-color toner images have been multiplex-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 a secondary transfer means) 26 arranged on the image bearing surface side of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is fed via a supply mechanism into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 at a predetermined timing, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has a negative polarity, the same as the negative polarity of the toner. Electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. The secondary transfer bias at this time is determined according to resistance detected by resistance detection means (not shown) that detects resistance in the secondary transfer section, and is voltage-controlled.

[0147] Thereafter, the recording paper P is sent to the pressure contact portion (nip portion) of a pair of fixing rolls in a fixing device (an example of fixing means) 28, where the toner image is fixed onto the recording paper P, forming a fixed image.

[0148] Examples of the recording paper P onto which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, etc. In addition to the recording paper P, examples of the recording medium include overhead projector sheets and the like. 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 in which the surface of plain paper is coated with resin or the like, or art paper for printing, is preferably used.

[0149] The recording paper P on which the color image has been fixed is conveyed toward the discharge section, and the series of color image forming operations is completed.

[0150] [Process cartridge / toner cartridge] The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment is a process cartridge that is detachably attached to an image forming apparatus and that contains the electrostatic image developer according to this embodiment and is equipped with a developing means that develops an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image.

[0151] The process cartridge according to this embodiment is not limited to the above configuration, but may also be configured to include a developing device and, if necessary, at least one other means selected from an image carrier, a charging means, an electrostatic image forming means, and a transfer means.

[0152] An example of a process cartridge according to the present embodiment will be described below, but the present invention is not limited to this. Note that only the main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0153] FIG. 2 is a schematic diagram showing the configuration of the process cartridge according to the present embodiment. The process cartridge 200 shown in FIG. 2 is configured to integrally combine and hold a photosensitive member 107 (an example of an image carrier), a charging roll 108 (an example of a charging means) provided around the photosensitive member 107, a developing device 111 (an example of a developing means), and a photosensitive member cleaning device 113 (an example of a cleaning means), which are held by a housing 117 provided with, for example, mounting rails 116 and an opening 118 for exposure, and is made into a cartridge. In FIG. 2, 109 denotes an exposure device (an example of an electrostatic image forming means), 112 denotes a transfer device (an example of a transfer means), 115 denotes a fixing device (an example of a fixing means), and 300 denotes recording paper (an example of a recording medium).

[0154] Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to the present embodiment is a toner cartridge that contains the toner according to the present embodiment and is detachably attached to an image forming apparatus. The toner cartridge contains replenishment toner to be supplied to a developing unit provided in the image forming apparatus.

[0155] 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to each developing device (color) by toner supply pipes (not shown). When the toner stored in a toner cartridge runs low, the toner cartridge is replaced. [Example]

[0156] Examples will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, all "parts" and "%" are by mass.

[0157] [Preparation of each particle dispersion] <Preparation of glitter pigment dispersion> Brilliant pigment (aluminum pigment paste, Toyo Aluminum 2173EA, number average particle size 6.3 μm, average length in the major axis direction 5.8 μm, aspect ratio 52): 100 parts Anionic surfactant (Daiichi Kogyo Seiyaku's Neogen R): 1.5 parts Ion-exchanged water: 900 parts After removing the solvent from the aluminum pigment paste, the above materials were mixed and dispersed for 1 hour using an emulsifying disperser (Pacific Machinery Co., Ltd., Cavitron CR1010) to obtain a brilliant pigment dispersion (solid concentration 10% by mass).

[0158] <Preparation of luminescent particle dispersion> Luminous particles (luminous pigment, manufactured by Nemoto Specialty Chemicals, product number LumiNova Effect Green N-FF, volume average particle size 3.2 μm, number average particle size 2.9 μm): 100 parts Anionic surfactant (Daiichi Kogyo Seiyaku's Neogen R): 1.5 parts Ion-exchanged water: 900 parts The above materials were mixed and dispersed for 1 hour using an emulsifying disperser (Cavitron CR1010 manufactured by Pacific Machinery Co., Ltd.) to obtain a luminescent particle dispersion (solid concentration: 10% by mass).

[0159] <Preparation of Amorphous Polyester Resin Particle Dispersion (1)> A reactor equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube was charged with 80 moles of polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane, 10 moles of ethylene glycol, 10 moles of cyclohexanediol, 80 moles of terephthalic acid, 10 moles of isophthalic acid, and 10 moles of n-dodecenylsuccinic acid, and the atmosphere in the reactor was purged with dry nitrogen gas. Then, 0.25 parts by mass of titanium tetrabutoxide was added as a catalyst per 100 parts by mass of the monomer components. After stirring and reacting for 3 hours under a nitrogen gas stream at 170°C, the temperature was further increased to 210°C over 1 hour, the pressure in the reactor was reduced to 3 kPa, and the reaction was continued under reduced pressure for 13 hours with stirring to obtain amorphous polyester resin (1) with a weight-average molecular weight of 5,320 and a glass transition temperature of 60.1°C.

[0160] Next, 200 parts by mass of amorphous polyester resin (1), 100 parts by mass of methyl ethyl ketone, and 70 parts by mass of isopropyl alcohol were placed in a jacketed 3-liter reactor (Tokyo Rikakikai Co., Ltd.: BJ-30N) equipped with a condenser, a thermometer, a water dripping device, and an anchor blade. The resin was dissolved by stirring and mixing at 100 rpm while maintaining the temperature at 70 ° C. in a water-circulating thermostatic bath. The stirring speed was then increased to 150 rpm, the water-circulating thermostatic bath was set to 66 ° C., and 10 parts by mass of 10% ammonia water (reagent) was added over 10 minutes. After that, a total of 600 parts by mass of ion-exchanged water maintained at 66 ° C. was added dropwise at a rate of 5 parts by mass / min to cause phase inversion, resulting in an emulsion. 600 parts of the resulting emulsion and 525 parts by mass of ion-exchanged water were placed in a 2-liter recovery flask and placed in an evaporator (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. While rotating the recovery flask, the pressure was increased to 60°C in a hot water bath, and the pressure was reduced to 7 kPa, taking care to prevent bumping, to remove the solvent. When the amount of recovered solvent reached 825 parts by mass, the pressure was returned to normal, and the recovery flask was cooled with water to obtain a dispersion containing resin particles with a volume average particle size of 160 nm. Ion-exchanged water was added to obtain an amorphous polyester resin particle dispersion (1) with a solids concentration of 20% by mass.

[0161] <Preparation of Amorphous Polyester Resin Particle Dispersion (2)> A reactor equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube was charged with 30 moles of polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane, 70 moles of ethylene glycol, 20 moles of cyclohexanediol, 80 moles of terephthalic acid, 20 moles of isophthalic acid, and 20 moles of n-dodecenylsuccinic acid, and the atmosphere in the reactor was purged with dry nitrogen gas. Then, 0.25 parts by mass of titanium tetrabutoxide was added as a catalyst per 100 parts by mass of the monomer components. After stirring and reacting for 3 hours at 170°C under a nitrogen gas stream, the temperature was further increased to 210°C over 1 hour, the pressure in the reactor was reduced to 3 kPa, and the reaction was continued under reduced pressure for 13 hours with stirring to obtain amorphous polyester resin (2) with a weight-average molecular weight of 8,130 and a glass transition temperature of 56.1°C.

[0162] Next, 200 parts by mass of amorphous polyester resin (2), 100 parts by mass of methyl ethyl ketone, and 70 parts by mass of isopropyl alcohol were placed in a jacketed 3-liter reactor (Tokyo Rikakikai Co., Ltd.: BJ-30N) equipped with a condenser, a thermometer, a water dripping device, and an anchor blade. The resin was dissolved by stirring and mixing at 100 rpm while maintaining the temperature at 70 ° C. in a water-circulating thermostatic bath. The stirring speed was then increased to 150 rpm, the water-circulating thermostatic bath was set to 66 ° C., and 10 parts by mass of 10% ammonia water (reagent) was added over 10 minutes. After that, a total of 600 parts by mass of ion-exchanged water maintained at 66 ° C. was added dropwise at a rate of 5 parts by mass / min to cause phase inversion, resulting in an emulsion. 600 parts of the resulting emulsion and 525 parts by mass of ion-exchanged water were placed in a 2-liter recovery flask and placed in an evaporator (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. While rotating the recovery flask, the pressure was increased to 60°C in a hot water bath, and the pressure was reduced to 7 kPa, taking care to prevent bumping, to remove the solvent. When the amount of recovered solvent reached 825 parts by mass, the pressure was returned to normal, and the recovery flask was cooled with water to obtain a dispersion containing resin particles with a volume average particle size of 165 nm. Ion-exchanged water was added to obtain an amorphous polyester resin particle dispersion (2) with a solids concentration of 20% by mass.

[0163] <Preparation of Amorphous Polyester Resin Particle Dispersion (3)> Bisphenol A ethylene oxide 2 mole adduct: 20 mole% Bisphenol A propylene oxide 2 mole adduct: 30 mole% Terephthalic acid: 30 mol% Dodecenyl succinic anhydride: 10 mol% Trimellitic anhydride: 10 mol% The above monomer components were charged into a reaction vessel equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet tube. After the atmosphere in the reaction vessel was replaced with dry nitrogen gas, 1.0% of dibutyltin oxide relative to the total amount of the above monomer components was added as a catalyst, and the mixture was stirred and reacted at about 190°C for 6 hours under a nitrogen gas stream. The temperature was then raised to 240°C and the mixture was stirred and reacted for 6 hours. After that, the pressure inside the reaction vessel was reduced to 10.0 mmHg, and the mixture was stirred and reacted under reduced pressure for 0.5 hours, thereby obtaining an amorphous polyester resin (3) having a weight average molecular weight of 9,430 and a glass transition temperature of 65°C.

[0164] Next, 200 parts by mass of amorphous polyester resin (3), 100 parts by mass of methyl ethyl ketone, and 70 parts by mass of isopropyl alcohol were placed in a jacketed 3-liter reactor (Tokyo Rikakikai Co., Ltd.: BJ-30N) equipped with a condenser, thermometer, water dripping device, and anchor blades, and the resin was dissolved by stirring and mixing at 100 rpm while maintaining the temperature at 70 ° C. in a water-circulating thermostatic bath. The stirring speed was then increased to 150 rpm, the water-circulating thermostatic bath was set to 66 ° C., and 10 parts by mass of 10% ammonia water (reagent) was added over 10 minutes. After that, a total of 600 parts by mass of ion-exchanged water maintained at 66 ° C. was added dropwise at a rate of 5 parts by mass / min to cause phase inversion, resulting in an emulsion. 600 parts of the resulting emulsion and 525 parts by mass of ion-exchanged water were placed in a 2-liter recovery flask and placed in an evaporator (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. While rotating the recovery flask, the pressure was increased to 60°C in a hot water bath, and the pressure was reduced to 7 kPa, taking care to prevent bumping, to remove the solvent. When the amount of recovered solvent reached 825 parts by mass, the pressure was returned to normal, and the recovery flask was cooled with water to obtain a dispersion containing resin particles with a volume average particle size of 163 nm. Ion-exchanged water was added to obtain an amorphous polyester resin particle dispersion (3) with a solids concentration of 20% by mass.

[0165] <Preparation of Crystalline Polyester Resin Particle Dispersion> 1,10-decanedicarboxylic acid: 260 parts by mass 1,6-Hexanediol: 167 parts by mass Dibutyltin oxide (catalyst): 0.3 parts by mass The above materials were placed in a heated and dried three-necked flask, the air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed at 180°C for 5 hours using mechanical stirring. The temperature was then gradually increased to 230°C under reduced pressure and stirred for 2 hours. When the mixture became viscous, it was air-cooled to stop the reaction. This yielded a crystalline polyester resin with a weight-average molecular weight of 12,600 and a melting temperature of 73°C.

[0166] 90 parts of crystalline polyester resin, 1.8 parts of anionic surfactant (TaycaPower, manufactured by Tayca Corporation), and 210 parts of ion-exchanged water were mixed, heated to 120°C, and dispersed using a homogenizer (Ultra Turrax T50 manufactured by IKA Corporation), followed by dispersion treatment using a pressure-discharge Gaulin homogenizer for 1 hour to obtain a resin particle dispersion containing dispersed resin particles with a volume average particle size of 160 nm. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20 mass%, thereby obtaining a crystalline polyester resin particle dispersion.

[0167] <Preparation of Release Agent Particle Dispersion> Paraffin wax (manufactured by Nippon Seiro Co., Ltd., FNP92, endothermic peak onset 81°C): 45 parts by mass Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts by mass Ion-exchanged water: 200 parts by weight The above ingredients were mixed and heated to 95°C, and dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA). After that, a dispersion treatment was carried out using a Manton-Gaulin high-pressure homogenizer (Gaulin), and a release agent particle dispersion liquid (solid content concentration: 20% by mass) in which the release agent particles were dispersed was prepared. The volume average particle size of the release agent particles was 0.19 μm.

[0168] <Preparation of Colorant Particle Dispersion> Yellow pigment (BASF, HANSA BRILLIANT YELLOW 5GX 03 (Pigment Yellow 74)): 98 parts by weight Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen R): 2 parts by mass Ion-exchanged water: 400 parts by weight The above ingredients were mixed and dissolved, and dispersed for 10 minutes using a homogenizer (IKA Ultra Turrax), to obtain a colorant particle dispersion having a median particle size of 0.16 μm and a solid content of 20% by mass.

[0169] [Toner production] Example 1 (Preparation of core particle dispersion) Amorphous polyester resin particle dispersion (1): 40 parts Amorphous polyester resin particle dispersion (2): 40 parts Crystalline polyester resin particle dispersion: 100 parts Brilliant pigment dispersion: 500 parts Release agent particle dispersion: 60 parts Nonionic surfactant (Igepal CA897): 1.40 parts The raw materials were placed in a 2 L cylindrical stainless steel container (diameter 30 cm) and dispersed for 10 minutes using a homogenizer (IKA Ultra Turrax T50) at 4000 rpm while applying shear force. Next, 0.56 parts of a 10% by mass aqueous solution of polyaluminum chloride was gradually added dropwise, and the homogenizer was rotated at 5000 rpm for 15 minutes to obtain a raw material dispersion. The raw material dispersion was then transferred to a polymerization kettle equipped with a stirrer with two paddles and a thermometer, and heating was started with a mantle heater while stirring at a rotation speed of 200 rpm, and the mixture was maintained at 54°C for 2 hours to form composite core particles, thereby obtaining a composite core particle dispersion in which the composite core particles were dispersed. During this process, the pH of the dispersion was controlled to 2.2 to 3.5 with 0.3N nitric acid and 1N aqueous sodium hydroxide solution.

[0170] (Resin particle layer formation process) Next, 100 parts of amorphous polyester resin particle dispersion (1) and 100 parts of amorphous polyester resin particle dispersion (2) were added to the composite core particle dispersion, and 0.47 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surfaces of the composite core particles and form a resin particle layer. The mixture was then heated to 54°C and held for 0.5 hours while checking the shape and size of the composite core particles with the resin particle layer using an optical microscope and a Multisizer II (Beckman Coulter).

[0171] (Repeat process) Next, 155 parts of amorphous polyester resin particle dispersion (1) and 155 parts of amorphous polyester resin particle dispersion (2) were added to the composite core particle dispersion with one resin particle layer formed, and 0.72 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 60°C and held for 0.5 hours while checking the shape and size of the composite core particles with the resin particle layer formed using an optical microscope and a Multisizer II (Beckman Coulter). This yielded an aggregated particle dispersion with dispersed aggregated particles.

[0172] (fusion / unification process) The pH was then raised to 8.0, and the temperature was then raised to 80.0°C to fuse the aggregated particles. While maintaining the temperature at 80.0°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (1). The volume average particle size of the toner particles (1) was 10.0 μm.

[0173] The obtained toner particles (1) are toner particles in which a shell layer composed of two resin layers, an innermost layer made of an amorphous resin and an outermost layer made of an amorphous resin, is formed on the surface of a composite core particle. The total mass of the shell layer is 105 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.3 μm. The number of bright pigment particles contained in one composite core particle was 3.4 on average, and the content of bright pigment particles relative to the entire composite core particle was 51% by mass.

[0174] (Preparation of externally added toner) 100 parts of the obtained toner particles (1) and 1.5 parts of hydrophobic silica (RY50 manufactured by Nippon Aerosil) were mixed in a Henschel mixer at a peripheral speed of 33 m / s for 2 minutes, and then sieved through a vibrating sieve with 45 μm openings to obtain toner (1) with external additives.

[0175] <Example 2> (Preparation of core particle dispersion) The above-mentioned bright pigment dispersion was used as it was as the single core particle dispersion.

[0176] (Resin particle layer formation process) To 500 parts of the single-core particle dispersion, 100 parts of the amorphous polyester resin particle dispersion (1), 100 parts of the amorphous polyester resin particle dispersion (2), 60 parts of the release agent particle dispersion, and 100 parts of the crystalline polyester resin particle dispersion were added. 0.84 parts of a 10% by weight aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to deposit the amorphous resin particles, release agent particles, and crystalline resin particles onto the surfaces of the single-core particles, forming a resin particle layer. The mixture was then heated to 54°C and held for 0.5 hours while observing the shape and size of the single-core particles with a resin particle layer using an optical microscope and a Multisizer II (Beckman Coulter).

[0177] (Repeat process) Next, 195 parts of amorphous polyester resin particle dispersion (1) and 195 parts of amorphous polyester resin particle dispersion (2) were added to the dispersion of single core particles with one resin particle layer formed, and 0.91 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 60°C and held for 0.5 hours while checking the shape and size of the single core particles with the resin particle layer formed using an optical microscope and a Multisizer II (Beckman Coulter). This yielded a dispersion of aggregated particles.

[0178] (fusion / unification process) Next, the pH was raised to 8.0, and the temperature was raised to 80.0°C to fuse the aggregated particles. While maintaining the temperature at 80.0°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (2). The volume average particle size of the toner particles (2) was 10.2 μm.

[0179] The obtained toner particles (2) are toner particles in which a shell layer composed of two resin layers, namely, an innermost layer composed of an amorphous resin, a release agent, and a crystalline resin, and an outermost layer composed of an amorphous resin, is formed on the surface of a single core particle. The total mass of the shell layer is 300 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.5 μm.

[0180] (Preparation of externally added toner) Toner (2) was obtained in the same manner as toner (1), except that toner particles (2) were used instead of toner particles (1).

[0181] Example 3 (Preparation of core particle dispersion) The above-mentioned bright pigment dispersion was used as it was as the single core particle dispersion.

[0182] (Resin particle layer formation process) To 500 parts of the single-core particle dispersion, 90 parts of amorphous polyester resin particle dispersion (1) and 90 parts of amorphous polyester resin particle dispersion (2) were added, and 0.42 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surface of the single-core particles, forming a resin particle layer. The mixture was then heated to 54°C and held for 0.5 hours while checking the shape and size of the single-core particles on which the resin particle layer was formed using an optical microscope and a Multisizer II (Beckman Coulter).

[0183] (Repeat process) Next, 100 parts of amorphous polyester resin particle dispersion (1), 100 parts of amorphous polyester resin particle dispersion (2), and 60 parts of release agent particle dispersion were added to the dispersion of single core particles with one resin particle layer formed, and 0.61 parts of a 10% by mass aqueous solution of polyaluminum chloride as a flocculant was gradually added dropwise to form a resin particle layer that would become an intermediate layer. The mixture was then heated to 56°C and held for 0.5 hours while the shape and size of the single core particles with the resin particle layer formed were confirmed using an optical microscope and a Multisizer II (Beckman Coulter). Next, 155 parts of amorphous polyester resin particle dispersion (1) and 155 parts of amorphous polyester resin particle dispersion (2) were added to the dispersion of single core particles with two resin particle layers, and 0.72 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 58°C and held for 0.5 hours while checking the shape and size of the single core particles with the resin particle layers using an optical microscope and a Multisizer II (Beckman Coulter). This yielded a dispersion of aggregated particles.

[0184] (fusion / unification process) Next, the pH was raised to 8.0, and the temperature was raised to 80.0°C to fuse the aggregated particles. While maintaining the temperature at 80.0°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (3). The volume average particle size of the toner particles (3) was 10.1 μm.

[0185] The obtained toner particles (3) are toner particles in which a shell layer composed of three resin layers, namely, an innermost layer made of an amorphous resin, a middle layer made of an amorphous resin and a release agent, and an outermost layer made of an amorphous resin, is formed on the surface of a single core particle. The total mass of the shell layer is 300 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.4 μm.

[0186] (Preparation of externally added toner) Toner (3) was obtained in the same manner as toner (1), except that toner particles (3) were used instead of toner particles (1).

[0187] Example 4 (Preparation of core particle dispersion) The above-mentioned bright pigment dispersion was used as it was as the single core particle dispersion.

[0188] (Resin particle layer formation process) To 500 parts of the single-core particle dispersion, 90 parts of amorphous polyester resin particle dispersion (1) and 90 parts of amorphous polyester resin particle dispersion (2) were added, and 0.42 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surface of the single-core particles, forming a resin particle layer. The mixture was then heated to 54°C and held for 0.5 hours while checking the shape and size of the single-core particles on which the resin particle layer was formed using an optical microscope and a Multisizer II (Beckman Coulter).

[0189] (Repeat process) Next, 50 parts of amorphous polyester resin particle dispersion (1), 50 parts of amorphous polyester resin particle dispersion (2), 60 parts of release agent particle dispersion, and 100 parts of crystalline polyester resin particle dispersion were added to the dispersion of single core particles with one resin particle layer formed, and 0.61 parts of a 10% by weight aqueous solution of polyaluminum chloride was gradually added dropwise as a flocculant to form a resin particle layer that would become an intermediate layer. The mixture was then heated to 56°C and held for 0.5 hours while the shape and size of the single core particles with the resin particle layer formed were confirmed using an optical microscope and a Multisizer II (Beckman Coulter). Next, 155 parts of amorphous polyester resin particle dispersion (1) and 155 parts of amorphous polyester resin particle dispersion (2) were added to the dispersion of single core particles with two resin particle layers, and 0.72 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 58°C and held for 0.5 hours while checking the shape and size of the single core particles with the resin particle layers using an optical microscope and a Multisizer II (Beckman Coulter). This yielded a dispersion of aggregated particles.

[0190] (fusion / unification process) Next, the pH was raised to 8.0, and the temperature was raised to 67.5°C to fuse the aggregated particles. While maintaining the temperature at 67.5°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (4). The volume average particle size of the toner particles (4) was 10.3 μm.

[0191] The obtained toner particles (4) are toner particles in which a shell layer composed of three resin layers, namely, an innermost layer made of an amorphous resin, a middle layer made of an amorphous resin, a release agent, and a crystalline resin, and an outermost layer made of an amorphous resin, is formed on the surface of a single core particle. The total mass of the shell layer is 300 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.3 μm.

[0192] (Preparation of externally added toner) Toner (4) was obtained in the same manner as toner (1), except that toner particles (4) were used instead of toner particles (1).

[0193] <Example 5> (Preparation of core particle dispersion) The above-mentioned bright pigment dispersion was used as it was as the single core particle dispersion.

[0194] (Resin particle layer formation process) To 500 parts of the single-core particle dispersion, 90 parts of amorphous polyester resin particle dispersion (1) and 90 parts of amorphous polyester resin particle dispersion (2) were added, and 0.42 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surface of the single-core particles, forming a resin particle layer. The mixture was then heated to 54°C and held for 0.5 hours while checking the shape and size of the single-core particles on which the resin particle layer was formed using an optical microscope and a Multisizer II (Beckman Coulter).

[0195] (Repeat process) Next, 25 parts of amorphous polyester resin particle dispersion (1), 25 parts of amorphous polyester resin particle dispersion (2), 60 parts of release agent particle dispersion, 100 parts of crystalline polyester resin particle dispersion, and 50 parts of colorant particle dispersion were added to the dispersion of single core particles with one resin particle layer formed. 0.61 parts of a 10% by weight aqueous solution of polyaluminum chloride was gradually added dropwise as a flocculant to form a resin particle layer that would become an intermediate layer. The mixture was then heated to 56°C and held for 0.5 hours while the shape and size of the single core particles with the resin particle layer formed were confirmed using an optical microscope and a Multisizer II (Beckman Coulter). Next, 155 parts of amorphous polyester resin particle dispersion (1) and 155 parts of amorphous polyester resin particle dispersion (2) were added to the dispersion of single core particles with two resin particle layers, and 0.72 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 58°C and held for 0.5 hours while checking the shape and size of the single core particles with the resin particle layers using an optical microscope and a Multisizer II (Beckman Coulter). This yielded a dispersion of aggregated particles.

[0196] (fusion / unification process) Next, the pH was raised to 8.0, and the temperature was raised to 80.0°C to fuse the aggregated particles. While maintaining the temperature at 80.0°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (5). The volume average particle size of the toner particles (5) was 10.2 μm.

[0197] The obtained toner particles (5) are toner particles in which a shell layer composed of three resin layers, namely, an innermost layer made of an amorphous resin, an intermediate layer made of an amorphous resin, a release agent, a crystalline resin, and a colorant, and an outermost layer made of an amorphous resin, is formed on the surface of a single core particle. The total mass of the shell layer is 300 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.7 μm.

[0198] (Preparation of externally added toner) Toner (5) was obtained in the same manner as toner (1), except that toner particles (5) were used instead of toner particles (1).

[0199] Example 6 (Preparation of core particle dispersion) The above-mentioned bright pigment dispersion was used as it was as the single core particle dispersion.

[0200] (Resin particle layer formation process) To 500 parts of the single-core particle dispersion, 50 parts of amorphous polyester resin particle dispersion (1) and 50 parts of amorphous polyester resin particle dispersion (2) were added, and 0.23 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surface of the single-core particles, forming a resin particle layer. The mixture was then heated to 52°C and held for 0.5 hours while checking the shape and size of the single-core particles on which the resin particle layer was formed using an optical microscope and a Multisizer II (Beckman Coulter).

[0201] (Repeat process) Next, 25 parts of amorphous polyester resin particle dispersion (1), 25 parts of amorphous polyester resin particle dispersion (2), 20 parts of release agent particle dispersion, 40 parts of crystalline polyester resin particle dispersion, and 20 parts of colorant particle dispersion were added to the dispersion of single core particles with one resin particle layer formed. 0.30 parts of a 10% by weight aqueous solution of polyaluminum chloride was gradually added dropwise as a flocculant to form a resin particle layer that would become the first intermediate layer. The mixture was then heated to 54°C and held for 0.5 hours while the shape and size of the single core particles with the resin particle layer formed were confirmed using an optical microscope and a Multisizer II (Beckman Coulter). Next, 40 parts of amorphous polyester resin particle dispersion (1), 40 parts of amorphous polyester resin particle dispersion (2), 40 parts of release agent particle dispersion, 60 parts of crystalline polyester resin particle dispersion, and 30 parts of colorant particle dispersion were added to the dispersion of single core particles with two resin particle layers formed. 0.49 parts of a 10% by weight aqueous solution of polyaluminum chloride was gradually added dropwise as a flocculant to form a second intermediate layer. The mixture was then heated to 56°C and held for 0.5 hours while the shape and size of the single core particles with the resin particle layers formed were confirmed using an optical microscope and a Multisizer II (Beckman Coulter). Next, 155 parts of amorphous polyester resin particle dispersion (1) and 155 parts of amorphous polyester resin particle dispersion (2) were added to the dispersion of single core particles with three resin particle layers, and 0.72 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 58°C and held for 0.5 hours while checking the shape and size of the single core particles with the resin particle layers using an optical microscope and a Multisizer II (Beckman Coulter). This yielded a dispersion of aggregated particles.

[0202] (fusion / unification process) Next, the pH was raised to 8.0, and the temperature was raised to 80·0°C to fuse the aggregated particles. While maintaining the temperature at 80·0°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (6). The volume average particle size of the toner particles (6) was 10.1 μm.

[0203] The obtained toner particles (6) are toner particles in which a shell layer composed of four resin layers is formed on the surface of a single core particle: an innermost layer made of an amorphous resin, a first intermediate layer made of an amorphous resin, a release agent, a crystalline resin, and a colorant, a second intermediate layer made of an amorphous resin, a release agent, a crystalline resin, and a colorant, and an outermost layer made of an amorphous resin. The total mass of the shell layer is 300 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.5 μm.

[0204] (Preparation of externally added toner) Toner (6) was obtained in the same manner as toner (1), except that toner particles (6) were used instead of toner particles (1).

[0205] Example 7 (Preparation of core particle dispersion) The above-mentioned bright pigment dispersion was used as it was as the single core particle dispersion.

[0206] (Resin particle layer formation process) To 500 parts of the single-core particle dispersion, 90 parts of amorphous polyester resin particle dispersion (1) and 90 parts of amorphous polyester resin particle dispersion (2) were added, and 0.42 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surface of the single-core particles, forming a resin particle layer. The mixture was then heated to 54°C and held for 0.5 hours while checking the shape and size of the single-core particles on which the resin particle layer was formed using an optical microscope and a Multisizer II (Beckman Coulter).

[0207] (Repeat process) Next, 50 parts of amorphous polyester resin particle dispersion (1), 50 parts of amorphous polyester resin particle dispersion (2), 60 parts of release agent particle dispersion, and 100 parts of crystalline polyester resin particle dispersion were added to the dispersion of single core particles with one resin particle layer formed, and 0.61 parts of a 10% by weight aqueous solution of polyaluminum chloride was gradually added dropwise as a flocculant to form a resin particle layer that would become an intermediate layer. The mixture was then heated to 56°C and held for 0.5 hours while the shape and size of the single core particles with the resin particle layer formed were confirmed using an optical microscope and a Multisizer II (Beckman Coulter). Next, 310 parts of amorphous polyester resin particle dispersion (3) was added to the dispersion of single core particles with two resin particle layers, and 0.72 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 58°C and held for 0.5 hours while checking the shape and size of the single core particles with the resin particle layers using an optical microscope and a Multisizer II (Beckman Coulter). This yielded a dispersion of aggregated particles.

[0208] (fusion / unification process) Next, the pH was raised to 8.0, and the temperature was raised to 80.0°C to fuse the aggregated particles. While maintaining the temperature at 80.0°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (7). The volume average particle size of the toner particles (7) was 10.2 μm.

[0209] The obtained toner particles (7) are toner particles in which a shell layer composed of three resin layers, namely, an innermost layer made of an amorphous resin, a middle layer made of an amorphous resin, a release agent, and a crystalline resin, and an outermost layer made of an amorphous resin, is formed on the surface of a single core particle. The total mass of the shell layer is 300 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.3 μm.

[0210] (Preparation of externally added toner) Toner (7) was obtained in the same manner as toner (1), except that toner particles (7) were used instead of toner particles (1).

[0211] Example 8 (Preparation of core particle dispersion) The light-emitting particle dispersion liquid was used as it was as the single core particle dispersion liquid.

[0212] (Resin particle layer formation process) To 500 parts of the luminescent particle dispersion (single-core particle dispersion), 90 parts of amorphous polyester resin particle dispersion (1) and 90 parts of amorphous polyester resin particle dispersion (2) were added, and 0.42 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surface of the single-core particles, forming a resin particle layer. The mixture was then heated to 54°C and held for 0.5 hours while observing the shape and size of the single-core particles on which the resin particle layer was formed using an optical microscope and a Multisizer II (Beckman Coulter).

[0213] (Repeat process) Next, 50 parts of amorphous polyester resin particle dispersion (1), 50 parts of amorphous polyester resin particle dispersion (2), 60 parts of release agent particle dispersion, and 100 parts of crystalline polyester resin particle dispersion were added to the dispersion of single core particles with one resin particle layer formed, and 0.61 parts of a 10% by weight aqueous solution of polyaluminum chloride was gradually added dropwise as a flocculant to form a resin particle layer that would become an intermediate layer. The mixture was then heated to 56°C and held for 0.5 hours while the shape and size of the single core particles with the resin particle layer formed were confirmed using an optical microscope and a Multisizer II (Beckman Coulter). Next, 155 parts of amorphous polyester resin particle dispersion (1) and 155 parts of amorphous polyester resin particle dispersion (2) were added to the dispersion of single core particles with two resin particle layers, and 0.72 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 58°C and held for 0.5 hours while checking the shape and size of the single core particles with the resin particle layers using an optical microscope and a Multisizer II (Beckman Coulter). This yielded a dispersion of aggregated particles.

[0214] (fusion / unification process) Next, the pH was raised to 8.0, and the temperature was raised to 80.0°C to fuse the aggregated particles. While maintaining the temperature at 80.0°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (8). The volume average particle size of the toner particles (8) was 9.9 μm.

[0215] The obtained toner particles (8) are toner particles in which a shell layer composed of three resin layers, namely, an innermost layer made of an amorphous resin, a middle layer made of an amorphous resin, a release agent, and a crystalline resin, and an outermost layer made of an amorphous resin, is formed on the surface of a single core particle. The total mass of the shell layer is 300 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.1 μm.

[0216] (Preparation of externally added toner) Toner (8) was obtained in the same manner as toner (1), except that toner particles (8) were used instead of toner particles (1).

[0217] <Comparative Example 1> (Preparation of core particle dispersion) In the same manner as in Example 1, a composite core particle dispersion liquid in which composite core particles were dispersed was obtained.

[0218] (Resin particle layer formation process) Next, 255 parts of amorphous polyester resin particle dispersion (1) and 255 parts of amorphous polyester resin particle dispersion (2) were added to the composite core particle dispersion, and 1.19 parts of a 10% by weight aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surfaces of the composite core particles and form a resin particle layer. The mixture was then heated to 58°C and held for 1.0 hour while checking the shape and size of the composite core particles with the resin particle layer formed using an optical microscope and a Multisizer II (Beckman Coulter). This yielded an aggregated particle dispersion containing dispersed aggregated particles.

[0219] (fusion / unification process) The pH was then raised to 8.0, and the temperature was then raised to 80.0°C to fuse the aggregated particles. While maintaining the temperature at 80.0°C, the pH was lowered to 6.0. After 1 hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (C1). The volume average particle size of the toner particles (C1) was 9.9 μm.

[0220] The obtained toner particles (C1) are toner particles in which a shell layer consisting of only one resin layer made of an amorphous resin is formed on the surface of a composite core particle. The total mass of the shell layer is 105 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.1 μm. The number of bright pigment particles contained in one composite core particle was 3.7 on average, and the content of bright pigment particles relative to the entire composite core particle was 51% by mass.

[0221] (Preparation of externally added toner) Toner (C1) was obtained in the same manner as toner (1), except that toner particles (C1) were used instead of toner particles (1).

[0222] <Comparative Example 2> (Preparation of core particle dispersion) The above-mentioned bright pigment dispersion was used as it was as the single core particle dispersion.

[0223] (Resin particle layer formation process) To 500 parts of the single-core particle dispersion, 140 parts of amorphous polyester resin particle dispersion (1) and 140 parts of amorphous polyester resin particle dispersion (2) were added, and 0.65 parts of a 10% by mass aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to adhere the amorphous resin particles to the surface of the single-core particles, forming a resin particle layer. The mixture was then heated to 54°C and held for 0.5 hours while checking the shape and size of the single-core particles on which the resin particle layer was formed using an optical microscope and a Multisizer II (Beckman Coulter).

[0224] (Repeat process) Next, 155 parts of amorphous polyester resin particle dispersion (1), 155 parts of amorphous polyester resin particle dispersion (2), 60 parts of release agent particle dispersion, and 100 parts of crystalline polyester resin particle dispersion were added to the dispersion of single core particles with one resin particle layer formed. 1.10 parts of a 10% by weight aqueous solution of polyaluminum chloride was slowly added dropwise as a flocculant to form the outermost resin particle layer. The mixture was then heated to 57°C and held for 0.5 hours while observing the shape and size of the single core particles with the resin particle layer formed using an optical microscope and a Multisizer II (Beckman Coulter). This yielded a dispersion of aggregated particles.

[0225] (fusion / unification process) The pH was then raised to 8.0, and the temperature was raised to 80.0°C to fuse the aggregated particles. While maintaining the temperature at 80.0°C, the pH was lowered to 6.0. After one hour, heating was stopped and the mixture was cooled at a rate of 0.1°C / min. The mixture was then sieved through a 20μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (C2). The volume average particle size of the toner particles (C2) was 10.2μm.

[0226] The obtained toner particles (C2) are toner particles in which a shell layer consisting of two resin layers, namely, an innermost layer made of an amorphous resin and an outermost layer made of an amorphous resin, a release agent, and a crystalline resin, is formed on the surface of a single core particle. The total mass of the shell layer is 300 parts by mass per 100 parts by mass of the core particle, and the total thickness of the shell layer is 1.9 μm.

[0227] (Preparation of externally added toner) Toner (C2) was obtained in the same manner as toner (1), except that toner particles (C2) were used instead of toner particles (1).

[0228] The compositions of the toners obtained in the above examples and comparative examples are shown in Table 1. The content (mass %) of resin particles alone relative to the total toner particles obtained in the above examples and comparative examples is also shown in Table 1. In Table 1, "Composite" indicates composite core particles, "Single" indicates single core particles, "Amo" indicates amorphous resin, "WAX" indicates release agent, and "Cry" indicates crystalline resin.

[0229] [evaluation] <Creating the carrier> 100 parts by mass of ferrite particles (manufactured by Powder Tech Co., Ltd., average particle size 50 μm) and 1.5 parts by mass of polymethyl methacrylate resin (manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 95,000, the proportion of components with a weight average molecular weight of 10,000 or less is 5% by mass) were placed in a pressure kneader together with 500 parts by mass of toluene, stirred and mixed at room temperature (25°C) for 15 minutes, and then heated to 70°C while mixing under reduced pressure to distill off the toluene, then cooled and classified using a 105 μm sieve to obtain a resin-coated ferrite carrier.

[0230] <Preparation of developer> The obtained toner was mixed with a resin-coated ferrite carrier to prepare a developer with a toner concentration of 7% by mass.

[0231] <Evaluation of fine line reproducibility> A Fuji Xerox "700 Digital Color Press" was prepared, and the developer obtained in each Example and Comparative Example was loaded into its developing unit. After leaving the press for 12 hours in a 5°C, 20% RH environment, 100,000 1% print charts were printed on A4 paper in the same environment. A 1-on-1-off image (an image in which one-dot lines are arranged in parallel at one-dot intervals) with a resolution of 2,400 dpi (dots per inch) was printed as a 5 cm x 5 cm chart perpendicular to the development direction at the top left, center, and bottom right of the A4 paper for the initial (10th sheet), 1,000th, 10,000th, 50,000th, and 100,000th sheets, as well as after leaving the press for 72 hours after printing the 100,000th sheet. The line spacing of each chart printed on the obtained sample was observed using a 100x magnifying glass with a scale to see if there were any areas that had narrowed due to toner scattering or any areas that had widened due to thin lines becoming thinner. Based on the observation results and the line spacing of the observed areas, a grade was evaluated according to the following criteria. The results are shown in Table 2.

[0232] -Evaluation criteria- G1: In all charts, there is no decrease in line spacing due to scattering or increase in line spacing due to thinning. G2: There is a decrease or increase in line spacing, but there is at least one chart with visible thin lines. G3: There is at least one chart where the spacing between thin lines is indistinguishable or where thin lines are missing. G4: There are two or more charts where the spacing between thin lines cannot be determined or where thin lines are missing.

[0233] <Evaluation of graininess> The obtained developer was filled into a developing device of a "modified color 800 press" manufactured by Fuji Xerox Co., Ltd. After filling the developer, it was left to stand in an environment of 35°C and 80% RH for 72 hours. Using this modified machine, in an environment of 35°C and 80% RH, a toner load of 4.0 g / m2 was applied to J paper (basis weight 82 g / m2: manufactured by Fuji Xerox Co., Ltd.). 2Patch images of 20 mm x 20 mm in size were formed with an image density of 10% to 100% in 10% increments, and the roughness was visually evaluated according to the following criteria. The results are shown in Table 2.

[0234] -standard- G1: No noticeable graininess at all. G2: Slight graininess is noticeable. G3: Graininess is noticeable, but not a problem. G4: Graininess is noticeable and it feels unnatural. G5: Graininess is strongly felt.

[0235] <Evaluation of gloss unevenness> In an environment with a temperature of 28.5°C and humidity of 85%, a modified DocuCentreColor400 (manufactured by Fuji Xerox Co., Ltd.) was used to print A4 size recording paper (manufactured by Fuji Xerox Co., Ltd., basis weight 64 g / m 2 An image with 100% image density was formed on the surface of the paper, and the 60-degree gloss was measured at 10 points using a gloss meter (BYK Micro Trigloss Gloss Meter (20+60+85°), manufactured by Gardner). Gloss unevenness was evaluated from the difference in gloss (maximum value - minimum value) and standard deviation at the 10 points. The evaluation criteria were as follows. The results are shown in Table 2.

[0236] -Evaluation criteria- G1: The difference in gloss is less than 5% and the standard deviation of 10 gloss measurements is 2 or less G2: The difference in gloss is less than 5% and the standard deviation of 10 gloss measurements is more than 2. G3: Gloss difference is 5% or more but less than 7.5% G4: Gloss difference is 7.5% or more and less than 10% G5: Gloss difference is 10% or more

[0237] [Table 1]

[0238] [Table 2]

[0239] From the above results, it can be seen that the toner of this example has higher fine line reproducibility than the toner of the comparative example. [Explanation of symbols]

[0240] 1Y, 1M, 1C, 1K Photoconductor (an example of an image carrier) 2Y, 2M, 2C, 2K Charging roll (an example of charging means) 3. Exposure device (an example of an electrostatic image forming means) 3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing device (an example of 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 cartridges 10Y, 10M, 10C, 10K image forming units 20 Intermediate transfer belt (an example of an intermediate transfer body) 22 Drive Roll 24 Support Roll 26 Secondary transfer roll (an example of a secondary transfer means) 30 Intermediate transfer body cleaning device 107 Photosensitive body (an example of an image carrier) 108 Charging roll (an example of charging means) 109 Exposure device (an example of electrostatic image forming means) 111 Developing device (an example of developing means) 112 Transfer device (an example of transfer means) 113 Photosensitive drum cleaning device (an example of cleaning means) 115 Fixing device (an example of fixing means) 116 Mounting Rail 117 Cabinet 118 Exposure opening 200 Process Cartridge 300 Recording paper (an example of a recording medium) P Recording paper (an example of a recording medium)

Claims

1. core particles having a number average particle size of 1 μm or more; a shell layer comprising two or more resin layers containing an amorphous resin and covering the surface of the core particle, wherein the outermost layer of the two or more resin layers is a resin layer made of the amorphous resin; and and toner particles having the shell layer is composed of three or more resin layers containing an amorphous resin, the innermost layer of the three or more resin layers is a resin layer made of the amorphous resin, an intermediate layer, which is a layer other than the outermost layer and the innermost layer among the three or more resin layers, includes a resin layer containing the amorphous resin and at least one selected from the group consisting of a release agent, a crystalline resin, and a colorant; The toner for developing electrostatic images, wherein the large particles include scaly particles.

2. 2. The toner for developing electrostatic images according to claim 1, wherein one of said core particles is composed of one of said large-diameter particles.

3. 2. The toner for developing electrostatic images according to claim 1, wherein one core particle contains two or more of the large-diameter particles and an amorphous resin.

4. 4. The toner for developing electrostatic images according to claim 3, wherein the content of the large diameter particles relative to the total amount of the core particles is 50% by mass or more.

5. 5. The electrostatic image developing toner according to claim 1, wherein the toner does not contain resin particles alone that contain an amorphous resin and do not contain the large-diameter particles, or the content of the resin particles alone is 80% by number or less of the entire toner for developing electrostatic images.

6. a core particle dispersion preparation step of preparing a core particle dispersion in which core particles having a number average particle diameter of 1 μm or more are dispersed; a resin particle layer forming step of adding amorphous resin particles to the core particle dispersion and aggregating the amorphous resin particles so that the amorphous resin particles adhere to the core particles, thereby forming a resin particle layer on the surfaces of the core particles; a repeating step of repeating the above operation one or more times, in which the particles added in the final step are only the amorphous resin particles, thereby forming aggregated particles having two or more resin particle layers on the surface of the core particle, the outermost layer of which is made of the amorphous resin particles; a fusion / coalescence step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles; and the particles added in the resin particle layer forming step are the amorphous resin particles alone, The repeating step is a step of repeating the above operation two or more times, in which the particles added in one or more of the operations excluding the last one contain the amorphous resin particles and at least one particle selected from the group consisting of release agent particles, crystalline resin particles, and colorant particles, thereby forming aggregated particles having three or more resin particle layers on the surface of the core particle, the innermost layer of the three or more resin particle layers being made of the amorphous resin particles, and intermediate layers, which are layers other than the outermost and innermost layers of the three or more resin particle layers, containing the amorphous resin particles and at least one particle selected from the group consisting of the release agent particles, the crystalline resin particles, and the colorant particles, The method for producing a toner for developing electrostatic images, wherein the large-diameter particles include scaly particles.

7. 7. The method for producing a toner for developing electrostatic images according to claim 6, wherein one core particle is composed of one large particle.

8. 7. The method for producing a toner for developing electrostatic images according to claim 6, wherein one core particle contains two or more of the large diameter particles and an amorphous resin.

9. The method for producing a toner for developing electrostatic images according to claim 8 , wherein the content of the large diameter particles relative to the total amount of the core particles is 50% by mass or more.

10. 10. The method for producing a toner for developing an electrostatic image according to claim 6, wherein an aggregating agent is added to the core particle dispersion in addition to the amorphous resin particles in all operations of the resin particle layer forming step and the repeating step.

11. The method for producing a toner for developing electrostatic images according to any one of claims 6 to 10, wherein the aggregation temperature in each operation of the repeating steps is higher than the aggregation temperature in the operation immediately before.

12. 12. The method for producing a toner for developing electrostatic images according to claim 6, wherein an amount of the amorphous resin particles added in each operation of the repeating step is greater than an amount of the amorphous resin particles added in an operation immediately before the operation.

13. An electrostatic image developer comprising the toner for developing electrostatic images according to any one of claims 1 to 5.

14. A toner for developing electrostatic images according to any one of claims 1 to 5 is contained therein, A toner cartridge that is detachably attached to an image forming device.

15. a developing unit containing the electrostatic image developer according to claim 13 and developing an electrostatic image formed on the surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge is detachably mounted in an image forming apparatus.

16. an image carrier; a charging means for charging the surface of the image carrier; an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; a developing unit containing the electrostatic image developer according to claim 13 and developing the electrostatic image formed on the surface of the image carrier into a toner image by the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing means for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising:

Images