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

Abstract

To provide a toner for developing electrostatic images that exhibits excellent suppression of density unevenness in high-humidity environments. [Solution] A toner for developing electrostatic images, comprising toner particles containing a binder resin, a release agent, and resin particles forming domains inside the toner particles, wherein the binder resin contains a polyester resin, the average ester group concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less, and when the ester group concentration of the resin particles is c2, the value of c2 / c1 is 0.30 or more and 0.70 or less.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a method for producing a toner (Z) containing a colorant, a crystalline resin (A), and a vinyl resin (B) having an ester group, wherein the vinyl resin (B) has at least one peak in the molecular weight range of 3,000 to 60,000 in the molecular weight distribution obtained by gel permeation chromatography, the ester group concentration of the vinyl resin (B) is 14 to 55% by weight based on the weight of (B), the content of the vinyl resin (B) is 50 to 90% by weight based on the weight of the toner (Z), and first, an aggregate (Y) obtained by aggregating a dispersion (X) in a dispersion (W) containing a colorant, a crystalline resin (A), and a vinyl resin (B) is heated and fused to obtain resin particles (Z'). A method for producing the toner (Z) is disclosed, which includes this step.

[0003] Patent Document 2 discloses an electrostatic charge image developing toner having toner particles containing a polyester resin composed of a polycondensate of a polyvalent carboxylic acid and a polyvalent alcohol, the polyvalent alcohol containing ethylene glycol, and the mass ratio of the ethylene glycol to all the polyvalent alcohols being 40% by mass or more and 90% by mass or less, and an external additive containing silica particles having a product of the volume average particle diameter D50 (μm) and the BET specific surface area SA (m 2 / g) of 1.4×10 3 or more and 5.0×10 3 or less.

[0004] Patent Document 3 discloses a toner for electrostatic latent image development, comprising a plurality of toner particles having a sea-like domain substantially composed of a plurality of resins, each containing at least a polyester resin with an alcohol component having 2 to 6 carbon atoms, and a plurality of island-like domains distributed in an island-like manner relative to the sea-like domain, wherein the island-like domains are substantially composed of a resin containing a nigrosine dye, the dispersion diameter of the island-like domains is 0.1 μm to 1.0 μm, the sea-like domains contain the polyester resin with the alcohol component having 2 to 6 carbon atoms in a ratio of 5% to 50% by mass relative to the total amount of the plurality of resins, and the ratio of the SP value of the resin constituting the sea-like domains to the SP value of the resin constituting the island-like domains is 0.98 or less or 1.20 or more.

[0005] Patent Document 4 discloses an electrostatic latent image developing toner containing a binder resin, a colorant, and a release agent, characterized in that it contains less than 3% by weight of a styrene copolymer having a weight-average molecular weight (Mw) in the range of 70,000 to 300,000 and an acid value (AV) in the range of 70 mg KOH / g to 220 mg KOH / g. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-74761 [Patent Document 2] Japanese Patent Publication No. 2018-163200 [Patent Document 3] Japanese Patent Publication No. 2017-142409 [Patent Document 4] Japanese Patent Publication No. 2008-15023 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This embodiment aims to provide a toner for electrostatic image development that has superior suppression of density unevenness under high humidity conditions (25°C 80%RH) compared to cases where the binder resin includes a polyester resin, the average ester group concentration c1 of the binder resin is less than 25% by mass or greater than 48% by mass, or where the c2 / c1 value is less than 0.30 or greater than 0.70 when the ester group concentration of the resin particles is c2. [Means for solving the problem]

[0008] The following embodiments are included as specific means for solving the aforementioned problems. <1> A toner for developing electrostatic images, comprising toner particles containing a binder resin, a release agent, and resin particles forming domains within the toner particles, wherein the binder resin contains a polyester resin, the average ester group concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less, and when the ester group concentration of the resin particles is c2, the value of c2 / c1 is 0.30 or more and 0.70 or less. <2> The content of the release agent is 1% by mass or more and 10% by mass or less, relative to the total mass of the toner particles. <1> Toner for developing electrostatic images as described above. <3> When the content of the mold release agent in the toner particles is Ww and the content of the resin particles is Wb, the value of Wb / Ww is 0.3 or more and 5.0 or less. <1> or <2> Toner for developing electrostatic images as described above. <4> The average circular equivalent diameter of the domains formed by the resin particles is between 50 nm and 300 nm. <1> ~ <3> A toner for developing electrostatic images, as described in one of the following. <5> The melting point of the aforementioned release agent is 60°C or higher and 120°C or lower. <1> ~ <4> A toner for developing electrostatic images, as described in one of the following. <6> The resin particles are styrene (meth)acrylic resin particles. <1> ~ <5> A toner for developing electrostatic images, as described in one of the following. <7> The resin particles are crosslinked resin particles. <1> ~ <6> A toner for developing electrostatic images, as described in one of the following. <8> The tetrahydrofuran-insoluble content of the resin particles is 80% by mass or more. <1> ~ <7> A toner for developing electrostatic images, as described in one of the following. <9> The mold release agent comprises at least one selected from the group consisting of hydrocarbon waxes and ester waxes. <1> ~ <8> A toner for developing electrostatic images, as described in one of the following. <10> The ester group concentration c3 of the aforementioned release agent is 15% by mass or less. <1> ~ <9> A toner for developing electrostatic images, as described in one of the following. <11> <1> ~ <10> A electrostatic image developer containing an electrostatic image developing toner as described in any one of the following. <12> <1> ~ <10> A toner cartridge that contains the electrostatic image developing toner described in any one of the above, and is attached to and detached from an image forming apparatus. <13> <11> A process cartridge that is attached to and detached from an image forming apparatus, comprising a developing device that contains the electrostatic image developer described above and develops an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer. <14> An image holder, a charging device for charging the surface of the image holder, and an electrostatic image forming device for forming an electrostatic image on the charged surface of the image holder, <11> An image forming apparatus comprising: a developing device that contains the electrostatic image developer described in [reference] and develops the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer; a transferring device that transfers the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing device that fixes the toner image transferred to the surface of the recording medium. <15> A charging step of charging the surface of the image holder, and a static charge image forming step of forming a static charge image on the charged surface of the image holder, <11> An image forming method comprising: a developing step of developing an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer described in [reference]; a transfer step of transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium. [Effects of the Invention]

[0009] <1> or <9> According to the present invention, a toner for developing electrostatic images is provided that has toner particles comprising a binder resin, a release agent, and resin particles forming domains inside the toner particles, wherein the binder resin includes a polyester resin, and the average ester group concentration c1 of the binder resin is less than 25% by mass or greater than 48% by mass, or, when the ester group concentration of the resin particles is c2, the c2 / c1 value is less than 0.30 or greater than 0.70, compared to the case where the binder resin includes a polyester resin and the average ester group concentration c1 of the binder resin is less than 25% by mass or greater than 48% by mass, or the c2 / c1 value is less than 0.30 or greater than 0.70. <2> According to the invention, a toner for developing electrostatic images is provided that exhibits superior ability to suppress density unevenness in a high-humidity environment compared to cases where the release agent content is less than 1% by mass or more than 10% by mass relative to the total mass of the toner particles. <3> According to the invention, when the content of the mold release agent in the toner particles is Ww and the content of the resin particles is Wb, a toner for electrostatic image development is provided that is superior in suppressing density unevenness in a high humidity environment compared to cases where the Wb / Ww value is less than 0.3 or greater than 5.0. <4> According to the invention, a toner for developing electrostatic images is provided that exhibits superior suppression of density unevenness in high humidity environments compared to cases where the average equivalent circle diameter of the domains formed by the resin particles is less than 50 nm or greater than 300 nm. <5> According to the invention, a toner for developing electrostatic images is provided that exhibits superior ability to suppress density unevenness in a high-humidity environment compared to cases where the melting point of the release agent is less than 60°C or more than 120°C. <6> According to the invention, a toner for developing electrostatic images is provided that is superior in suppressing density unevenness in a high-humidity environment compared to the case where the resin particles are polyester resin particles. <7> According to the invention, a toner for developing electrostatic images is provided that is superior in suppressing density unevenness in a high-humidity environment compared to the case where the resin particles are resin particles that do not have a crosslinking structure. According to the invention related to <8>, there is provided an electrostatic charge image developing toner that is more excellent in density unevenness suppression in a high-humidity environment than when the tetrahydrofuran-insoluble content of the resin particles is less than 80% by mass. According to the invention related to <10>, there is provided an electrostatic charge image developing toner that is more excellent in density unevenness suppression in a high-humidity environment than when the ester group concentration c3 of the release agent is more than 15% by mass. According to the inventions related to <11>, <12>, <13>, <14> or <15>, there are provided an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method that have toner particles containing a binder resin, a release agent, and resin particles forming domains inside the toner particles, the binder resin contains a polyester resin, the average ester group concentration c1 of the binder resin is less than 25% by mass or more than 48% by mass, or when the ester group concentration of the resin particles is c2, the value of c2 / c1 is less than 0.30 or more than 0.70, and that are more excellent in density unevenness suppression in a high-humidity environment than when using an electrostatic charge image developing toner.

Brief Description of the Drawings

[0010] [Figure 1] It is a schematic configuration diagram showing an image forming apparatus according to the present embodiment. [Figure 2] It is a schematic configuration diagram showing a process cartridge according to the present embodiment.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the embodiments of the present embodiment will be described. These descriptions and examples are illustrative of the embodiment and do not limit the scope of the embodiment.

[0012] In the present embodiment, the numerical range indicated using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described in stages within this embodiment, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described within this embodiment, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0013] In this embodiment, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their objective is achieved.

[0014] In this embodiment, each component may contain multiple types of the corresponding substance. In this embodiment, when referring to the amount of each component in the composition, if there are multiple types of the substance corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple types of substances present in the composition. In this embodiment, each component may contain multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for a mixture of such multiple types of particles present in the composition, unless otherwise specified.

[0015] In this embodiment, "(meth)acrylic" is an expression that includes both acrylic and methacrylic, and "(meth)acrylate" is an expression that includes both acrylate and methacrylate. In this embodiment, "electrostatic image developing toner" is also referred to as "toner."

[0016] (Toner for developing electrostatic images) The electrostatic image developing toner according to this embodiment has toner particles comprising a binder resin, a release agent, and resin particles forming domains inside the toner particles, wherein the binder resin comprises a polyester resin, the average ester group concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less, and when the ester group concentration of the resin particles is c2, the value of c2 / c1 is 0.30 or more and 0.70 or less.

[0017] Conventional toners, when printed in high-humidity environments, can cause problems such as poor fixing because the moisture absorbed by the paper draws heat away from the toner. While it is possible to improve fixing performance by controlling the hygroscopicity of the binder resin, this can also lead to the binder resin becoming more prone to softening, resulting in excessive seepage of the release agent onto the particle surface and causing uneven image density due to the release agent's offset. In the electrostatic image developing toner according to this embodiment, the average ester group concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less, and when the ester group concentration of the resin particles is c2, the value of c2 / c1 is 0.30 or more and 0.70 or less, which leads to the following estimation. First, it can be appropriately plasticized in a high humidity environment and ensure fixing performance to moisture-absorbing paper. Furthermore, when the binder resin begins to melt, the resin particles tend to aggregate, and at that time, the aggregates incorporate wax into the aggregates, thus suppressing the growth of the release agent. As a result, the amount of release agent seeping out is stable regardless of humidity, and the occurrence of density unevenness in the image can be suppressed even in a high humidity environment.

[0018] The configuration of the electrostatic image developing toner according to this embodiment will be described in detail below.

[0019] [Toner particles] The toner particles consist of a binder resin and resin particles, and optionally include colorants, release agents, and other additives.

[0020] <Ester group concentration> In the electrostatic image developing toner according to this embodiment, the average ester group concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less, and when the ester group concentration of the resin particles is c2, the value of c2 / c1 is 0.30 or more and 0.70 or less. The average ester group concentration c1 of the binder resin is preferably 28% by mass or more and 47% by mass or less, more preferably 30% by mass or more and 45% by mass or less, and particularly preferably 35% by mass or more and 43% by mass or less, from the viewpoint of suppressing concentration unevenness in a high humidity environment.

[0021] From the viewpoint of suppressing concentration unevenness in a high-humidity environment, the value of c2 / c1 is preferably, for example, 0.32 or more and 0.68 or less, more preferably 0.35 or more and 0.65 or less, and particularly preferably 0.40 or more and 0.60 or less.

[0022] From the viewpoint of suppressing concentration unevenness in a high-humidity environment, the ester group concentration c2 of the resin particles is preferably, for example, 7% by mass or more and 30% by mass or less, more preferably 10% by mass or more and 25% by mass or less, and particularly preferably 12% by mass or more and 21% by mass or less.

[0023] From the viewpoint of better demonstrating the effects of this embodiment, the ester group concentration c3 of the mold release agent is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, and particularly preferably 0% by mass.

[0024] The ester group concentration can be calculated from the number of ester groups [-C(=O)O-] in the resin or compound, and is specifically expressed by the following formula. Ester group concentration (mass%) = [(N x 44) / number average molecular weight] x 100 Here, N is the average number of ester groups per molecule, and 44 is the formula weight of the ester group [-C(=O)O-]. The chemical structure of a resin or compound is calculated by determining the monomer composition or chemical structure and the number of ester groups using nuclear magnetic resonance (NMR) spectroscopy or similar methods.

[0025] <Resin particles> The toner particles include resin particles that form domains within the toner particles. Examples of resin particles include polyolefin resins (polyethylene, polypropylene, etc.), styrene resins (polystyrene, α-polymethylstyrene, etc.), (meth)acrylic resins (polymethyl methacrylate, polyacrylonitrile, etc.), epoxy resins, polyurethane resins, polyurea resins, polyamide resins, polycarbonate resins, polyether resins, polyester resins, and copolymer resins thereof. As for the resin particles, styrene-(meth)acrylic resin particles are preferred, for example, from the viewpoint of suppressing concentration unevenness in high humidity environments.

[0026] -Average equivalent circular diameter of domains formed by resin particles- The average equivalent diameter of the domains formed by the resin particles is preferably 50 nm to 300 nm, more preferably 100 nm to 250 nm, and particularly preferably 120 nm to 190 nm, from the viewpoint of suppressing uneven concentration in a high-humidity environment.

[0027] The average equivalent diameter of the domains formed by resin particles is a value measured using a transmission electron microscope (TEM). For example, the JEM-2100plus, manufactured by JEOL Ltd., can be used as a transmission electron microscope. Specifically, the method for measuring the average equivalent diameter of the domains formed by resin particles is as follows: Toner particles are mixed with epoxy resin and embedded, and the epoxy resin is allowed to solidify. The resulting solidified material is cut into sections approximately 0.1 μm thick using a microtome. The obtained thin sections are stained with ruthenium tetroxide in a desiccator at 30°C. The stained thin sections are photographed at 10,000x magnification using a transmission electron microscope, and the equivalent circle diameter is calculated from the cross-sectional area of ​​100 internal resin particles dispersed within the toner particles. The arithmetic mean of these values ​​is then used as the average equivalent circle diameter.

[0028] -Insoluble matter of tetrahydrofuran- From the viewpoint of suppressing concentration unevenness in a high-humidity environment, the tetrahydrofuran-insoluble content of the resin particles is preferably 80% by mass or more, more preferably 85% by mass or more, and particularly preferably 90% by mass or more.

[0029] The method for measuring THF-insoluble content in this embodiment will be described below. (1) Weigh 0.25 g of the sample, add 40 mL of tetrahydrofuran to it, and mix and stir for 3 hours. (2) Subsequently, the mixture obtained in (1) is separated using a centrifuge at 2,000 rpm (revolutions per minute) for 30 minutes. (3) Weigh 5 mL of the supernatant obtained in (2) after centrifugation, transfer it to an aluminum dish, and evaporate and dry the tetrahydrofuran in a vacuum dryer heated to 50°C. (4) The THF-insoluble portion is calculated from the difference in mass of the aluminum tray before and after drying using the following formula. THF insoluble content [%] = {0.25 - [(mass of supernatant liquid and aluminum dish) - (mass of aluminum dish after drying)] × 8} / 0.25 × 100

[0030] -Monomer composition of styrene-(meth)acrylic resin particles- The styrene-(meth)acrylic resin particles in this embodiment include, for example, resin particles obtained by polymerizing styrene monomers and (meth)acrylic monomers such as (meth)acrylate monomers by radical polymerization.

[0031] Examples of styrene monomers include styrene, α-methylstyrene, vinylnaphthalene, alkyl-substituted styrenes having alkyl chains such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene, halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene, and fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene. Among these, styrene or α-methylstyrene is preferred, for example.

[0032] Examples of (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, and (meth)acrylic acid Examples include amyl, neopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, biphenyl (meth)acrylate, diphenylethyl (meth)acrylate, t-butylphenyl (meth)acrylate, terphenyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-carboxyethyl (meth)acrylate.

[0033] As for (meth)acrylate monomers, from the viewpoint of ease of adjusting the ester group concentration of styrene-(meth)acrylic resin, for example, (meth)acrylate compounds having an alkyl group with 2 to 12 carbon atoms (also called "number of carbon atoms") are preferred, (meth)acrylate compounds having an alkyl group with 2 to 10 carbon atoms are more preferred, and (meth)acrylate compounds having an alkyl group with 4 to 8 carbon atoms are particularly preferred. Among the (meth)acrylate monomers, n-butyl (meth)acrylate from styrene-(meth)acrylic resin is particularly preferred.

[0034] Furthermore, from the viewpoint of suppressing concentration unevenness in high-humidity environments, the resin particles are preferably, for example, cross-linked resin particles. Examples of crosslinking agents that form crosslinked structures include: aromatic polyfunctional vinyl compounds such as divinylbenzene and divinylnaphthalene; polyvinyl esters of aromatic polycarboxylic acids such as divinyl phthalate, divinyl isophthalate, divinyl terephthalate, divinyl homophthalate, divinyl trimesicate, trivinyl trimesicate, divinyl naphthalenedicarboxylate, and divinyl biphenylcarboxylate; divinyl esters of nitrogen-containing aromatic compounds such as divinyl pyridinedicarboxylate; vinyl esters of unsaturated heterocyclic carboxylic acid compounds such as vinyl pyromutinate, vinyl furanate, vinyl pyrrole-2-carboxylate, and vinyl thiophenecarboxylate; butanediol diacrylate, butanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, octanediol diacrylate, octanediol dimethacrylate, nonanediol diacrylate, nonanediol dimethacrylate, decanediol diacrylate, decanediol dimethacrylate Examples include (meth)acrylic acid esters of linear polyhydric alcohols such as thacrylate, dodecanediol diacrylate, and dodecanediol dimethacrylate; (meth)acrylic acid esters of branched and substituted polyhydric alcohols such as neopentyl glycol dimethacrylate and 2-hydroxy,1,3-diacryloxypropane; and polyfunctional vinyl esters of polycarboxylic acids such as polyethylene glycol di(meth)acrylate, polypropylene polyethylene glycol di(meth)acrylate, divinyl succinate, divinyl fumarate, vinyl maleate, divinyl maleate, divinyl diglycolate, vinyl itaconate, divinyl itaconate, divinyl acetonedicarboxylic acid, divinyl glutarate, divinyl 3,3'-thiodipropionate, divinyl trans-aconitate, trivinyl trans-aconitate, divinyl adipic acid, divinyl pimephosphate, divinyl suberate, divinyl azelaate, divinyl sebacate, divinyl dodecanediate, and divinyl brassylate. Crosslinking agents may be used individually or in combination of two or more types.

[0035] Among these, it is preferable to use alkylene glycol diacrylate having alkylene chains with 6 or more carbon atoms as the crosslinking agent. In other words, the resin particles have constituent units derived from alkylene glycol diacrylate, and it is preferable that the alkylene chains in the alkylene glycol diacrylate have 6 or more carbon atoms.

[0036] From the viewpoint of adjusting the crosslinking density to an appropriate range, the number of carbon atoms in the alkylene chain of alkylene glycol diacrylate is preferably 6 or more, more preferably 6 to 12, and even more preferably 8 to 12. More specific examples of alkylene glycol diacrylate include 1,6-hexanediol acrylate, 1,6-hexanediol methacrylate, 1,8-octanediol diacrylate, 1,8-octanediol dimethacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, 1,12-dodecanediol diacrylate, and 1,12-dodecanediol dimethacrylate, among which 1,10-decanediol diacrylate and 1,10-decanediol dimethacrylate are preferred.

[0037] The crosslinking agent content in the resin particle forming composition is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, more preferably 0.2 parts by mass or more and 3.0 parts by mass or less, and even more preferably 0.3 parts by mass or more and 2.5 parts by mass or less, based on 100 parts by mass of the total amount of monomers used.

[0038] The resin particle content is preferably, for example, 1% to 30% by mass, more preferably 3% to 25% by mass, and even more preferably 4% to 16% by mass, relative to the toner particles, from the viewpoint of suppressing density unevenness in a high-humidity environment.

[0039] <Release agent> The toner particles contain a release agent. Examples of release agents include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral / petroleum-based waxes such as montan wax; and ester waxes such as fatty acid esters and montanic acid esters. However, the release agents are not limited to these. In particular, from the viewpoint of further demonstrating the effects of this embodiment, it is preferable to include at least one selected from the group consisting of hydrocarbon waxes and ester waxes.

[0040] From the viewpoint of suppressing concentration unevenness in high humidity environments, the melting point of the release agent is preferably, for example, 60°C to 120°C, more preferably 63°C to 110°C, and particularly preferably 75°C to 100°C. The melting point is determined from the DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in JIS K 7121-1987 "Method for determining the transition temperature of plastics".

[0041] From the viewpoint of suppressing uneven concentration in a high-humidity environment, the release agent content is preferably 1% to 10% by mass, more preferably 2% to 9% by mass, and particularly preferably 3% to 8% by mass, based on the total mass of the toner particles.

[0042] Furthermore, when the content of the mold release agent in the toner particles is Ww and the content of the resin particles is Wb, the Wb / Ww value is preferably, for example, 0.3 or more and 5.0 or less, more preferably 0.5 or more and 4.0 or less, and particularly preferably greater than 1.0 and 3.0 or less, from the viewpoint of suppressing unevenness in concentration under high humidity conditions. Furthermore, from the viewpoint of suppressing uneven concentration in a high-humidity environment, it is preferable that the content Wb of the resin particles in the toner particles be greater than, for example, the content Ww of the release agent.

[0043] <Binding resin> The toner particles contain an amorphous polyester resin as a binder. Furthermore, the toner particles may contain a binder resin other than amorphous polyester resin. Examples of binder resins include vinyl resins consisting 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 binder 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 aforementioned vinyl resins; and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These binding resins may be used individually or in combination of two or more types.

[0044] For example, polyester resin is preferred as the binder resin. Examples of polyester resins include known amorphous polyester resins. In addition to amorphous polyester resins, crystalline polyester resins may also be used in combination.

[0045] Furthermore, the "crystalline nature" of a resin refers to the presence of a clear endothermic peak rather than a stepwise change in endothermic quantity in differential scanning calorimetry (DSC). Specifically, it means that the full width at half maximum of the endothermic peak measured at a heating rate of 10°C / min is within 10°C. On the other hand, "amorphous" resins refer to those with a full width at half maximum exceeding 10°C, exhibiting a stepwise change in endothermic capacity, or lacking a clear endothermic peak.

[0046] Amorphous polyester resin Examples of amorphous polyester resins include condensation polymers of polycarboxylic acids and polyhydric alcohols. The amorphous polyester resin may be a commercially available product or a synthesized one.

[0047] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid (hexenyl succinic acid, octenyl succinic acid, dodecenyl succinic acid, pentadecenyl succinic acid, etc.), adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., with 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. Polycarboxylic acids may be used in combination with dicarboxylic acids, or with trivalent or higher carboxylic acids that have a cross-linked or branched structure. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). Polycarboxylic acids may be used individually or in combination of two or more.

[0048] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyhydric alcohols, and aromatic diols are more preferred. As for the polyhydric alcohol, a trihydric or higher polyhydric alcohol with a cross-linked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. Polyhydric alcohols may be used individually or in combination of two or more types.

[0049] The glass transition temperature (Tg) of amorphous polyester resin is preferably, for example, 50°C to 80°C, and more preferably 50°C to 70°C. The glass transition temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, it is determined by the "extracorporeal glass transition onset temperature" described in the method for determining the glass transition temperature in JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics".

[0050] The weight-average molecular weight (Mw) of the amorphous polyester resin is preferably, for example, 5,000 to 1,000,000, and more preferably 7,000 to 500,000. The number-average molecular weight (Mn) of the amorphous polyester resin is preferably, for example, 2,000 to 100,000. The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 to 100, and more preferably 2 to 60. The weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (GPC). GPC molecular weight measurement is performed using a Tosoh Corporation GPC-HLC-8320GPC analyzer, a Tosoh Corporation TSKgel SuperHM-M (15cm) column, and tetrahydrofuran (THF) solvent. The weight-average molecular weight and number-average molecular weight are calculated from these measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0051] Amorphous polyester resins may be used individually or in combination of two or more types. When using two or more types in combination, for example, a high molecular weight resin and a low molecular weight resin may be used together.

[0052] Amorphous polyester resins can be obtained by well-known manufacturing methods. Specifically, for example, they can be obtained by a method in which the polymerization temperature is set to 180°C or higher and 230°C or lower, and the reaction system is subjected to reduced pressure as needed, while removing water and alcohol generated during condensation. If the monomers of the raw materials do not dissolve or become miscible at the reaction temperature, a high-boiling point solvent may be added as a solubilizer to dissolve them. In this case, the polycondensation reaction should be carried out while distilling off the solubilizer. If there are monomers with poor miscibility, for example, it is advisable to condense the poorly miscible monomers with the acid or alcohol to be polycondensed with them beforehand, and then polycondense them together with the main component.

[0053] • Crystalline polyester resin Crystalline polyester resins include, for example, polycondensates of polycarboxylic acids and polyhydric alcohols. Commercially available crystalline polyester resins may be used, or synthesized resins may be used. Here, since the crystalline polyester resin easily forms a crystalline structure, a polycondensate using a polymerizable monomer having linear aliphatic structures is preferred over a polymerizable monomer having aromatic structures, for example.

[0054] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., phthalic acid, isophthalic acid, terephthalic acid, dibasic acids such as naphthalene-2,6-dicarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). Polycarboxylic acids may be used in combination with dicarboxylic acids, or with trivalent or higher carboxylic acids that have a crosslinked or branched structure. Examples of trivalent carboxylic acids include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalentricarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). In addition to these dicarboxylic acids, polycarboxylic acids with sulfonic acid groups and dicarboxylic acids with ethylenic double bonds may also be used in combination. Polycarboxylic acids may be used individually or in combination of two or more.

[0055] Examples of polyhydric alcohols include aliphatic diols (for example, linear aliphatic diols with 2 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 1,20-eicosanediol. Among these, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols. Polyhydric alcohols may be used in combination with diols, including trihydric or higher alcohols that have a cross-linked or branched structure. Examples of trihydric or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. Polyhydric alcohols may be used individually or in combination of two or more types.

[0056] Here, the polyhydric alcohol often contains, for example, an aliphatic diol of 80 mol% or more, preferably 90 mol% or more.

[0057] The melting temperature of the crystalline polyester resin is preferably, for example, 50°C to 100°C, more preferably 55°C to 90°C, and even more preferably 60°C to 85°C. The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in JIS K7121-1987 "Method for determining the transition temperature of plastics".

[0058] The weight-average molecular weight (Mw) of the crystalline polyester resin is preferably, for example, 6,000 or more and 50,000 or less.

[0059] Crystalline polyester resins can be obtained, for example, by well-known manufacturing methods, similar to amorphous polyesters.

[0060] Furthermore, the polyester resin may be a hybrid resin having a polyester resin segment and a styrene-acrylic copolymer segment.

[0061] The binder resin content is preferably 40% to 95% by mass, more preferably 50% to 92% by mass, and even more preferably 55% to 90% by mass, relative to the total toner particles.

[0062] <Coloring agent> Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzidine yellow, surene yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, balkan orange, Watch Young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, risole red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, ultramarine blue, and calco oil blue. Examples include various pigments such as methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate; inorganic pigments such as titanium compounds, silica, aluminum, and mica; and various dyes such as acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindigo, dioxazine, thiazine, azomethine, indigo, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, and thiazole. The colorant is not limited to substances that absorb in the visible light region. For example, the colorant may be a substance that absorbs in the near-infrared region, a fluorescent colorant, or a colorant that exhibits luminescence. Colorants may be used individually or in combination of two or more types.

[0063] The coloring agent may be a surface-treated coloring agent as needed, and may be used in combination with a dispersant. Furthermore, multiple types of coloring agents may be used in combination.

[0064] The colorant content is preferably 1% to 30% by mass, and more preferably 3% to 15% by mass, relative to the total toner particles.

[0065] <Other additives> Other additives include well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are included in the toner particles as internal additives.

[0066] <Characteristics of toner particles, etc.> The toner particles may be single-layer toner particles, or they may be toner particles with a so-called core-shell structure, consisting of a core (core particle) and a coating layer (shell layer) that covers the core.

[0067] The volume-average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0068] The average particle size and particle size distribution indices of the toner particles are measured using a Coulter Multisizer 3 (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For 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 alkylbenzenesulfonate) as a dispersant. This is then added to 100 ml to 150 ml of electrolyte. The electrolyte containing the suspended sample is dispersed in an ultrasonic disperser for 1 minute. The particle size distribution of particles with a diameter of 2 μm to 60 μm is then measured using a Coulter Multisizer 3 with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the measured particle size distribution, a cumulative distribution of volume and number is drawn for each divided particle size range (channel) from the smallest diameter side. The particle size at which the cumulative total reaches 16% is defined as the volume particle size D16v and the number particle size D16p, the particle size at which the cumulative total reaches 50% is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size at which the cumulative total reaches 84% ​​is defined as the volume particle size D84v and the number particle size D84p. Using these, the volume particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 The GSDp index is (D84p / D16p) 1 / 2 It is calculated as follows.

[0069] The average circularity of the toner particles is preferably 0.90 or more and 1.00 or less, and more preferably 0.92 or more and 0.98 or less.

[0070] The average circularity of toner particles is determined by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle projection image)]. Specifically, it is a value measured by the following method. First, the toner particles to be measured are collected by suction, a flattened flow is formed, and a strobe flash is instantaneously activated to capture a still image of the particles. This particle image is then analyzed using a flow-type particle image analyzer (Paasche analyzer PAS, manufactured by Hosokawa Micron Corporation). The number of samples used to determine the average circularity is 10,000. If the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0071] [External additives] Examples of external additives include inorganic particles. These inorganic particles include SiO2, TiO2, Al2O3, SrTiO3, CaTiO3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, and K2O·(TiO2). n Examples include Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4.

[0072] The surface of the inorganic particles used as an external additive should preferably be subjected to a hydrophobic treatment, for example. The hydrophobic treatment is carried out by immersing the inorganic particles in a hydrophobic treatment agent, for example. The hydrophobic treatment agent is not particularly limited, but examples include silane-based coupling agents, silicone oil, titanate-based coupling agents, and aluminum-based coupling agents. These may be used individually or in combination of two or more. The amount of hydrophobic treatment agent is typically, for example, 1 to 10 parts by mass per 100 parts by mass of inorganic particles.

[0073] Examples of external additives include resin particles (such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), and cleaning lubricants (for example, metal salts of higher fatty acids represented by zinc stearate, and particles of higher alcohols).

[0074] The amount of external additive added is preferably 0.01% by mass or more and 10% by mass or less relative to the toner particles, and more preferably 0.01% by mass or more and 6.0% by mass or less.

[0075] [Method for manufacturing toner for electrostatic image development] The electrostatic image developing toner according to this embodiment is obtained by manufacturing toner particles and then adding an external additive to the toner particles.

[0076] Toner particles may be manufactured by either a dry method (e.g., kneading and grinding method) or a wet method (e.g., agglomeration, suspension polymerization, dissolution and suspension method). There are no particular restrictions on these manufacturing methods, and known methods can be used. Among these, for example, obtaining toner particles by agglomeration is preferable.

[0077] Specifically, for example, when manufacturing toner particles by an aggregation and coalescence method, for example, The process involves mixing a zero-grade resin particle dispersion containing zero-grade resin particles that form domains, a first-grade resin particle dispersion containing first-grade resin particles that become binder resins, a colorant dispersion containing a colorant, and a release agent particle dispersion containing release agent particles (hereinafter also referred to as "release agent particles"), and then agglomerating each particle and the colorant in the resulting dispersion to form first aggregated particles (first aggregated particle formation step), After obtaining a first aggregate particle dispersion in which the first aggregate particles are dispersed, a second resin particle, which will become a binder resin, is added to the first aggregate particle dispersion to aggregate the second resin particle on the surface of the first aggregate particles, thereby forming second aggregate particles (second aggregate particle formation step). The process involves heating the second aggregate particle dispersion, in which the second aggregate particles are dispersed, to fuse and combine the second aggregate particles and form toner particles (fusion and combination process), The toner particles are manufactured through this process. This aggregation and coalescence method is described as a method for producing toner particles containing a binder resin, a colorant, and a release agent; however, the colorant and release agent are components included in the toner particles as needed.

[0078] The details of each step are explained below.

[0079] -Each dispersion preparation process- First, prepare each dispersion used in the agglomeration and coalescence method. Specifically, prepare a zero-grade resin particle dispersion containing zero-grade resin particles that form domains, a first-grade resin particle dispersion containing first-grade resin particles that act as binders, a colorant dispersion containing colorants, a second-grade resin particle dispersion containing second-grade resin particles that act as binders, and a release agent particle dispersion containing release agent particles. In each dispersion preparation step, the 0th resin particle, the 1st resin particle, and the 2nd resin particle will be referred to as "resin particles" in the explanation.

[0080] Here, the resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium with a surfactant.

[0081] Examples of dispersion media used in resin particle dispersions include aqueous media. Examples of aqueous media include water such as distilled water and deionized water, and alcohols. These may be used individually or in combination of two or more.

[0082] Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycol, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly noteworthy. Nonionic surfactants may be used in combination with anionic or cationic surfactants. Surfactants may be used individually or in combination of two or more types.

[0083] In resin particle dispersions, common dispersion methods for dispersing resin particles in a dispersion medium include, for example, rotary shear homogenizers, ball mills with media, sand mills, and dyno mills. Depending on the type of resin particles, the resin particles may also be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method. Phase inversion emulsification is a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase) to neutralize it, and then an aqueous medium (W phase) is added. This causes a conversion of the resin from W / O to O / W (so-called phase inversion), resulting in a discontinuous phase, and the resin is dispersed in the aqueous medium in particulate form.

[0084] The volume-average particle size of the resin particles dispersed in the resin particle dispersion is preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and even more preferably 0.1 μm or more and 0.6 μm or less. The volume-average particle size of the resin particles is measured using a laser diffraction particle size distribution analyzer (e.g., LA-960, manufactured by Horiba, Ltd.). The particle size distribution is obtained by subtracting the cumulative distribution from the smallest particle size side for each divided particle size range (channel), and the particle size that accounts for 50% of the total particle size is measured as the volume-average particle size D50v. The volume-average particle size of particles in other dispersions is measured in the same manner.

[0085] The resin particle content in the resin particle dispersion is preferably, for example, 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0086] In addition, colorant dispersions and mold release agent particle dispersions are prepared in the same manner as the resin particle dispersions. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the resin particle dispersions are the same for the colorant dispersed in the colorant dispersion and the mold release agent particles dispersed in the mold release agent particle dispersion.

[0087] -First agglomerated particle formation process- Next, the 0th resin particle dispersion, the 1st resin particle dispersion, the colorant dispersion, and the mold release agent particle dispersion are mixed together. Then, in this mixed dispersion, the 0th resin particles, the 1st resin particles, the colorant, and the release agent particles are heteroaggregated to form the 1st aggregated particles containing the 0th resin particles, the 1st resin particles, the colorant, and the release agent particles.

[0088] Specifically, for example, a flocculant is added to a dispersion obtained by mixing a 0th resin particle dispersion, a 1st resin particle dispersion, a colorant dispersion, and a mold release agent particle dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, pH 2 to 5), a dispersion stabilizer is added as needed, and then the temperature is set to a range of 20°C to 50°C to flocce the particles dispersed in the mixed dispersion and form 1st flocculated particles. In the first agglomerated particle formation step, for example, the mixed dispersion may be stirred with a rotary shear homogenizer, the above-mentioned flocculant may be added at room temperature (e.g., 25°C), the pH of the mixed dispersion may be adjusted to acidic (e.g., pH 2 to 5), a dispersion stabilizer may be added as needed, and then the above-mentioned heating may be performed.

[0089] Examples of flocculants include surfactants with opposite polarity to the surfactant used as a dispersant added to a mixed dispersion, inorganic metal salts, and metal complexes with a valency of 2 or higher. In particular, when a metal complex is used as a flocculant, the amount of surfactant used is reduced and the electrostatic properties are improved. Additives that form complexes or similar bonds with the metal ions of the flocculant may be used as needed. Chelating agents are used as such additives.

[0090] 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. As a chelating agent, a water-soluble chelating agent may be used. Examples of chelating agents include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, as well as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). The amount of chelating agent to be added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the first resin particles, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass. Additionally, alkali may be added to adjust the pH of the system in order to control the effect of the chelating agent.

[0091] -Second agglomerated particle formation process- Next, after obtaining a first aggregate particle dispersion containing the first aggregate particles, a second resin particle dispersion containing the second resin particles is added to the first aggregate particle dispersion. The second resin particles may be of the same type as the first resin particles, or they may be of a different type.

[0092] Then, in a dispersion of first aggregated particles and second resin particles, the second resin particles are aggregated on the surface of the first aggregated particles. At this time, a release agent particle dispersion may also be added to aggregate the second resin particles and release agent particles on the surface of the first aggregated particles. Specifically, for example, in the first aggregated particle formation step, when the first aggregated particles reach the desired particle size, the second resin particle dispersion is added to the first aggregated particle dispersion, and heating is performed at a temperature below the glass transition temperature of the second resin particles. Then, by adjusting the pH of the dispersion to a range of, for example, between 6.5 and 8.5, the progression of aggregation is stopped. In this way, a second aggregated particle is obtained by agglomerating the first aggregated particle so that the second resin particle adheres to its surface.

[0093] -Fusion / coalescence process- Next, the second aggregate particle dispersion, in which the second aggregate particles are dispersed, is heated to a temperature above the glass transition temperature of the first and second resin particles (for example, 10 to 30°C higher than the glass transition temperature of the first and second resin particles) to fuse and combine the second aggregate particles and form toner particles. Additionally, the pH of the system may be adjusted by adding acid as needed to control the shape.

[0094] Toner particles are obtained through the above process. Furthermore, in the agglomeration and coalescence method described above, the second agglomeration particle formation step may be omitted, and the first agglomeration particles may be fused and coalesced to form toner particles. Alternatively, the second agglomeration particle formation step may be repeated multiple times.

[0095] Here, after the fusion and combination process is completed, the toner particles in the dispersion are subjected to known washing, solid-liquid separation, and drying processes to obtain dried toner particles. There are no particular restrictions on the washing process, but it is preferable to perform thorough displacement washing with deionized water from the standpoint of electrostatic charge. There are no particular restrictions on the solid-liquid separation process, but from the standpoint of productivity, it is preferable to perform suction filtration, pressure filtration, etc. There are no particular restrictions on the drying process, but from the standpoint of productivity, it is preferable to perform freeze-drying, air-flow drying, fluidized bed drying, vibratory fluidized bed drying, etc.

[0096] The toner according to this embodiment is manufactured, for example, by adding an external additive to the obtained dried toner particles and mixing them. Mixing can be performed using, for example, a V-blender, a Henschel mixer, a Redigge mixer, etc. The external additive may be mixed with the toner particles all at once, or the external additive may be added to the toner particles in stages and mixed multiple times. Furthermore, if necessary, coarse particles of toner may be removed using a vibrating screen separator, a wind screen separator, etc.

[0097] (Electrostatic image developer) The electrostatic image developer according to this embodiment includes at least the electrostatic image developing toner according to this embodiment. The electrostatic image developer according to this embodiment may be a one-component developer containing only the electrostatic image developing toner according to this embodiment, or it may be a two-component developer in which the electrostatic image developing toner and a carrier are mixed.

[0098] There are no particular restrictions on the carriers, and known carriers can be used. Examples of carriers include coated carriers in which a resin is coated on the surface of a core material made of magnetic powder; magnetic powder dispersed carriers in which magnetic powder is dispersed in a matrix resin; and resin-impregnated carriers in which resin is impregnated into porous magnetic powder. Magnetic powder dispersion carriers and resin-impregnated carriers may be carriers in which the constituent particles of the carrier are used as a core material and the surface thereof is coated with resin.

[0099] Examples of magnetic powders include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0100] In particular, magnetite and ferrite are preferred as magnetic powders. The magnetic powder may also be used as particles in which the magnetic powder is dispersed in a resin.

[0101] Examples of coating resins and matrix resins include styrene-(meth)acrylic acid resin; polyolefin resins such as polyethylene resin and polypropylene resin; polyvinyl or polyvinylidene resins such as polystyrene, (meth)acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylcarbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; straight silicone resins or modified products thereof consisting of organosiloxane bonds; fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate; amino resins such as urea-formaldehyde resin; epoxy resin; and the like. The coating resin and matrix resin preferably contain, for example, a (meth)acrylic resin, and more preferably a (meth)acrylic resin having an alicyclic structure. The coating resin and matrix resin may also contain nitrogen-containing (meth)acrylic resin. It is more preferable that the (meth)acrylic resin is contained in an amount of, for example, 50% by mass or more relative to the total mass of the coating resin and the matrix resin, and even more preferable that the (meth)acrylic resin is contained in an amount of 80% by mass or more relative to the total mass of the coating resin and the matrix resin. In particular, the coating resin and the matrix resin preferably include, for example, an alicyclic (meth)acrylic resin as the (meth)acrylic resin. The coating resin and matrix resin may contain conductive particles and other additives. Examples of conductive particles include metals such as gold, silver, and copper, as well as carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate. Other additives include metal oxide particles such as silica, titanium oxide, zinc oxide, and tin oxide; metal compound particles such as barium sulfate, aluminum borate, and potassium titanate; and metal particles such as gold, silver, and copper. Among these, silica particles are preferred, for example. The above particles are preferably contained in an amount of, for example, 10% to 60% by mass relative to the total mass of the resin layer.

[0102] To coat the surface of the core material with resin, one method is to coat it with a coating layer-forming solution prepared by dissolving the coating resin and various additives (used as needed) in a suitable solvent. The solvent is not particularly limited and should be selected considering the type of resin used and its suitability for coating. Specific resin coating methods include the immersion method, in which the core material is immersed in a coating layer forming solution; the spray method, in which the coating layer forming solution is sprayed onto the surface of the core material; the fluidized bed method, in which the coating layer forming solution is sprayed onto the core material while it is suspended by fluidized air; and the kneader coater method, in which the carrier core material and the coating layer forming solution are mixed in a kneader coater, and then the solvent is removed.

[0103] The mixing ratio (mass ratio) of toner and carrier in a two-component developer is preferably, for example, toner:carrier = 1:100 to 30:100, and more preferably 3:100 to 20:100.

[0104] (Image forming device, image forming method) The image forming apparatus and image forming method according to this embodiment will be described below. The image forming apparatus according to this embodiment comprises an image holder, a charging device for charging the surface of the image holder, an electrostatic image forming apparatus for forming an electrostatic image on the charged surface of the image holder, a developing apparatus for containing an electrostatic image developer and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, a transfer apparatus for transferring the toner image formed on the surface of the image holder to the surface of a recording medium, and a fixing apparatus for fixing the toner image transferred to the surface of the recording medium. The electrostatic image developer according to this embodiment is used as the electrostatic image developer.

[0105] The image forming apparatus according to this embodiment implements an image forming method (image forming method according to this embodiment) comprising: a charging step of charging the surface of an image holder; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image holder; a developing step of developing the electrostatic image formed on the surface of the image holder as a toner image using an electrostatic image developer according to this embodiment; a transfer step of transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0106] The image forming apparatus according to this embodiment may be a known image forming apparatus such as: a direct transfer apparatus that directly transfers a toner image formed on the surface of an image holder to a recording medium; an intermediate transfer apparatus that first transfers a toner image formed on the surface of an intermediate transfer body to the surface of an intermediate transfer body, and secondly transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; an apparatus equipped with a cleaning device that cleans the surface of the image holder after the transfer of the toner image and before charging, or an apparatus equipped with a static elimination device that irradiates the surface of the image holder with static elimination light to eliminate static charge after the transfer of the toner image and before charging; etc. In the case of an intermediate transfer method apparatus, the transfer apparatus may include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer apparatus that first transfers the toner image formed on the surface of the image holder to the surface of the intermediate transfer body; and a secondary transfer apparatus that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0107] In the image forming apparatus according to this embodiment, for example, the part including the developing device may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with a developing device that contains the electrostatic image developer according to this embodiment is preferably used.

[0108] The following is an example of an image forming apparatus according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will be omitted from the explanation.

[0109] Figure 1 is a schematic diagram showing the image forming apparatus according to this embodiment. The image forming apparatus shown in Figure 1 is equipped with first to fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K that output images of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side at predetermined distances from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may also be process cartridges that can be attached to and detached from the image forming apparatus.

[0110] In the drawings of each unit 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 is extended through each unit as an intermediate transfer body. The intermediate transfer belt 20 is wound around drive rolls 22 and support rolls 24 that are spaced apart from each other from left to right in the drawing and are in contact with the inner surface of the intermediate transfer belt 20, and is configured to travel in the direction from the first unit 10Y to the fourth unit 10K. The support rolls 24 are subjected to a force that moves away from the drive rolls 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around both. An intermediate transfer body cleaning device 30 is provided on the outer surface of the intermediate transfer belt 20, facing the drive rolls 22. Furthermore, each of the developing units (examples of developing units) 4Y, 4M, 4C, and 4K for each unit 10Y, 10M, 10C, and 10K is supplied with toner containing the four colors of toner: yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K.

[0111] Since the first to fourth units 10Y, 10M, 10C, and 10K have equivalent configurations, the first unit 10Y, which forms the yellow image and is located on the upstream side in the direction of travel of the intermediate transfer belt, will be described as a representative example. The descriptions of the second to fourth units 10M, 10C, and 10K will be omitted by assigning reference numerals to parts equivalent to the first unit 10Y, with magenta (M), cyan (C), and black (K) instead of yellow (Y).

[0112] The first unit 10Y has a photoreceptor 1Y that acts as an image holder. Surrounding the photoreceptor 1Y are a charging roll (an example of a charging device) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, an exposure device (an example of an electrostatic image forming device) 3 that exposes the charged surface with a laser beam 3Y based on a color-separated image signal to form an electrostatic image, a developing device (an example of a developing device) 4Y that supplies charged toner to the electrostatic image to develop the electrostatic image, a primary transfer roll 5Y (an example of a primary transfer device) that transfers the developed toner image onto an intermediate transfer belt 20, and a photoreceptor cleaning device that removes toner remaining on the surface of the photoreceptor 1Y after primary transfer. (Example of a cleaning device) 6Y are arranged in order. The primary transfer roll 5Y is positioned inside the intermediate transfer belt 20, facing the photoreceptor 1Y. Furthermore, each of the primary transfer rolls 5Y, 5M, 5C, and 5K is connected to a bias power supply (not shown) that applies a primary transfer bias. Each bias power supply varies the transfer bias applied to each primary transfer roll through control by a control unit (not shown).

[0113] The following describes the process of forming the yellow image in the first unit 10Y. First, prior to operation, the surface of the photoreceptor 1Y is charged to a potential of -600V to -800V by the charging roll 2Y. The photoreceptor 1Y is conductive (e.g., volume resistivity at 20°C: 1 × 10⁻⁶). -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate (less than Ωcm). This photosensitive layer normally has high resistance (resistance of general resin), but when irradiated with a laser beam 3Y, the resistivity of the irradiated area changes. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 according to image data for yellow sent from a control unit (not shown). The laser beam 3Y irradiates the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic image of the yellow image pattern on the surface of the photoreceptor 1Y.

[0114] A static charge image is an image formed on the surface of a photoreceptor 1Y due to charging. It is a so-called negative latent image formed when the resistivity of the irradiated portion of the photoreceptor layer decreases due to the laser beam 3Y, causing the charged material on the surface of the photoreceptor 1Y to flow, while the charge remains in the portion not irradiated by the laser beam 3Y. The electrostatic charge image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y moves. At this development position, the electrostatic charge image on the photoreceptor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0115] The developing device 4Y contains, for example, an electrostatic image developer including at least yellow toner and a carrier. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y and is held on the developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the static charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image on the surface of the photoreceptor 1Y, and the latent image is developed by the yellow toner. The photoreceptor 1Y, on which the yellow toner image has been formed, continues to move at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0116] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y acts on the toner image, transferring the toner image on the photoreceptor 1Y onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity opposite to the toner's polarity (-) (+), and for example, in the first unit 10Y, it is controlled to +10 μA by a control unit (not shown). Meanwhile, any toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0117] Furthermore, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K of the second unit from 10M onward is also controlled in accordance with the first unit. Thus, the intermediate transfer belt 20, on which the yellow toner image has been transferred in the first unit 10Y, is sequentially transported through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed and transferred in multiple layers.

[0118] Intermediate transfer belt 2 through which four-color toner images are multi-transferred via units 1 to 4. The process leads to a secondary transfer section, which consists of an 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 device) 26 positioned on the outer circumferential surface of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is fed via a supply mechanism into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 at a predetermined timing, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has the same polarity (-) as the toner's polarity (-), and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection device (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0119] After this, the recording paper P is fed to the contact area (nip area) of a pair of fixing rolls in a fixing device (an example of a fixing device) 28, where the toner image is fixed onto the recording paper P, and a fixed image is formed.

[0120] Examples of recording paper P used to transfer toner images include plain paper used in electrophotographic photocopiers and printers. Other recording media besides recording paper P include OHP sheets. To further improve the smoothness of the image surface after fixing, for example, the surface of the recording paper P is also preferably smooth. For example, coated paper, which is plain paper coated with resin or the like, or art paper for printing are preferably used.

[0121] Once the color image has been fixed onto the recording paper P, it is discharged towards the output section, and the series of color image formation operations is completed.

[0122] <Processor Cartridges / Toner Cartridges> The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment contains the electrostatic image developer according to this embodiment, and is equipped with a developing device that develops the electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer, and is a process cartridge that can be attached to and detached from an image forming apparatus.

[0123] The process cartridge according to this embodiment is not limited to the above configuration, and may also include a developing device and, as necessary, at least one other device selected from, for example, an image holder, a charging device, an electrostatic image forming device, and a transfer device.

[0124] The following shows an example of a process cartridge according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will not be explained.

[0125] Figure 2 is a schematic diagram showing the process cartridge according to this embodiment. The process cartridge 200 shown in Figure 2 is constructed by integrally holding a photoreceptor 107 (an example of an image holder), a charging roll 108 (an example of a charging device), a developing device 111 (an example of a developing device), and a photoreceptor cleaning device 113 (an example of a cleaning device) provided around the photoreceptor 107, using a housing 117 equipped with a mounting rail 116 and an opening 118 for exposure, and is then formed into a cartridge. In Figure 2, 109 represents an exposure apparatus (an example of an electrostatic image forming apparatus), 112 represents a transfer apparatus (an example of a transfer apparatus), 115 represents a fixing apparatus (an example of a fixing apparatus), and 300 represents recording paper (an example of a recording medium).

[0126] Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to this embodiment contains the toner according to this embodiment and forms an image. This is a toner cartridge that is attached to and detached from the device. The toner cartridge contains replenishment toner for supply to the developing device located within the image forming apparatus.

[0127] The image forming apparatus shown in Figure 1 is an image forming apparatus with removable toner cartridges 8Y, 8M, 8C, and 8K. The developing units 4Y, 4M, 4C, and 4K are connected to toner cartridges corresponding to each developing unit (color) by toner supply pipes (not shown). When the toner contained in a toner cartridge becomes low, the toner cartridge is replaced. [Examples]

[0128] The embodiments of the invention will be described in detail below with reference to examples, but the embodiments of the invention are not limited to these examples. In the following explanation, unless otherwise specified, "parts" and "%" refer to mass. Synthesis, processing, and manufacturing were carried out at room temperature (25°C ± 3°C) unless otherwise specified.

[0129] (Example 1) <Preparation of toner particles (1)> [Preparation of amorphous polyester resin dispersion (1) (PES1)] Terephthalic acid: 100 moles • Ethylene glycol: 60 moles • Propylene glycol: 30 moles • Bisphenol A propylene oxide 2 molar adduct: 10 moles The above materials were placed in a reaction vessel equipped with a stirrer, nitrogen inlet tube, temperature sensor, and rectification column, and the temperature was raised to 190°C over 1 hour. 1.2 parts of dibutyltin oxide were added for every 100 parts of the above materials. The temperature was raised to 240°C over 6 hours while distilling off the generated water, and then the dehydration condensation reaction was continued at 240°C for 3 hours. After cooling, amorphous polyester resin (1) was obtained. The ester group concentration of the obtained amorphous polyester resin (1) was 38.9% by mass.

[0130] Amorphous polyester resin (1): 100 parts • Methyl ethyl ketone: 60 parts Isopropanol: 15 parts • 10% ammonia aqueous solution: 3.6 parts The above materials were placed in a jacketed reaction vessel equipped with a condenser, thermometer, water dropper, and anchor blades, and the amorphous polyester resin (1) was dissolved while being stirred at 100 rpm in a water-circulating constant temperature bath while maintaining the liquid temperature at 50°C. Next, the water-circulating constant temperature bath was set to 40°C, and a total of 300 parts of ion-exchanged water, which had been kept at 40°C, were added dropwise at a rate of 3 parts / minute to invert the phase and form an emulsion. The resulting emulsion was placed in a round-bottom flask and set in an evaporator equipped with a vacuum control unit via a trap bulb. The round-bottom flask was heated in a 60°C water bath while rotating, and the pressure was reduced to 7 kPa while taking care to prevent bumping to remove the solvent. After returning to atmospheric pressure, the round-bottom flask was cooled with water to obtain a dispersion. Deionized water was added to the obtained dispersion to obtain an amorphous polyester resin dispersion (1) with a solid content of 20% by mass.

[0131] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (1)(B1)] -Preparation of emulsified solution (1)- <<Emulsion (1)>> • Styrene: 40 units n-butyl acrylate: 58.5 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified solution (1). In a reaction vessel equipped with a stirrer and a nitrogen inlet tube, the inside of the vessel was purged with nitrogen, and then 0.4 parts of anionic surfactant (Eleminol MON-2) and 100 parts of deionized water were added. The reaction solution was heated in an oil bath while stirring until the temperature of the reaction solution reached 70°C. 5 parts of emulsion (1) were added, and then 10 parts of an aqueous solution of ammonium persulfate adjusted to a concentration of 10% by mass was added, and the mixture was held for 30 minutes. Subsequently, while maintaining the temperature of the reaction solution at 70°C, 195 parts of emulsion (1) were gradually added to the reaction vessel by pump over a period of 60 minutes. After the dropwise addition was complete, the mixture was held for 60 minutes, then 1 part of 10% by mass ammonium persulfate was added, and the mixture was held for a further 3 hours before being cooled to room temperature. Subsequently, deionized water and nitric acid were added to achieve a solid content concentration of 20% by mass, to obtain styrene-(meth)acrylate copolymer particle dispersion (1). The ester group concentration of the obtained resin particles was 17.0% by mass.

[0132] [Preparation of mold release agent particle dispersion (1)] • Paraffin wax w1 (HNP9, manufactured by Nippon Seiro Co., Ltd.): 100 pieces • Anionic surfactant (Neoperex G-65, manufactured by Kao Corporation): 5 parts • Ion-exchanged water: 300 bottles The above materials were mixed and heated to 100°C, then dispersed using a homogenizer (Ultra-Turrax T50). Further dispersion was performed using a Manton-Gorin high-pressure homogenizer (Gorin Co., Ltd.), and deionized water was added to the dispersion to obtain a release agent particle dispersion (1) with a solid content of 20% by mass. The concentration of ester groups in the release agent particles in the release agent particle dispersion (1) was 0% by mass.

[0133] [Preparation of colorant particle dispersion] • Carbon black (Regel 330, manufactured by Cabot Corporation): 110 units • Anionic surfactant (Neoperex G-65, manufactured by Kao Corporation): 6 parts • Ion-exchanged water: 300 bottles The above materials were mixed and dispersed for 10 minutes using a homogenizer (Ultra-Turrax T50, IKA). Deionized water was added to the dispersion to obtain a colorant particle dispersion with a solid content of 20% by mass. The volume-average particle size of the colorant particles in the colorant particle dispersion was 220 nm.

[0134] <Preparation of toner (1)> Amorphous polyester resin dispersion (1) (solid content 20% by mass): 51 parts • Styrene-(meth)acrylate copolymer particle dispersion (1) (solid content 20% by mass): 8 parts • Coloring agent particle dispersion (solid content 20% by mass): 8 parts • Release agent particle dispersion (1) (solid content 20% by mass): 7 parts Anionic surfactant (Eleminol MON-2): 0.7 parts • Ion-exchanged water: 50 units The above materials were placed in a reaction vessel equipped with a thermometer, pH meter, and stirrer. The temperature of the reaction vessel was maintained at 20°C and stirred at 150 rpm for 30 minutes. Then, a 0.3N nitric acid aqueous solution was added to adjust the pH to 5.0, and a 2% aluminum sulfate aqueous solution was added while dispersing it in a homogenizer (Ultra-Turrax T50). Next, the temperature was raised to 45°C at a rate of 0.4°C / min while stirring and held for 30 minutes. Next, 26 parts of amorphous polyester resin particle dispersion (1) were added and held for 30 minutes. Then, a 1.0 N (= 1.0 mol / L) sodium hydroxide aqueous solution was added to adjust the pH to 8.5 and held for 15 minutes. After that, the temperature was raised to 80°C at a rate of 1°C / min while continuing to stir, and held at 80°C for 5 hours. Next, the mixture was cooled, solid-liquid separation was performed, and the solids were washed with deionized water. Finally, the mixture was dried in a freeze vacuum dryer for 24 hours to obtain toner particles (1) with a volume average particle size of 5.4 μm. Toner (1) was obtained by mixing 100 parts of toner particles (1) and 2.0 parts of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., product name: RY200) in a Henschel mixer. The C2 / C1 value for toner (1) was 0.44.

[0135] (Examples 2 to 27, and Comparative Examples 1 and 2) Toners were prepared in the same manner as in Example 1, except that the type and amount of amorphous polyester resin, resin particles, and release agent were changed to those listed in Table 1. The following describes the preparation methods for each amorphous polyester resin, the preparation methods for resin particles, and the types of release agents used.

[0136] [Preparation of amorphous polyester resin dispersion (2) (PES2)] In the preparation of amorphous polyester (1), amorphous polyester resin (2) was obtained in the same manner as described below, except that the preparation of the materials was changed. Terephthalic acid: 70 moles Fumaric acid: 30 moles • Ethylene glycol: 65 moles • Propylene glycol: 35 moles The ester group concentration of the obtained amorphous polyester resin (2) was 48.0% by mass.

[0137] In the preparation of amorphous polyester resin dispersion (1), amorphous polyester resin dispersion (2) with a solid content of 20% by mass was obtained in the same manner as in the preparation of amorphous polyester resin dispersion (1), except that amorphous polyester resin (1) was replaced with amorphous polyester resin (2).

[0138] [Preparation of amorphous polyester resin dispersion (3) (PES3)] In the preparation of amorphous polyester (1), amorphous polyester resin (3) was obtained in the same manner as described below, except that the preparation of the materials was changed. Terephthalic acid: 80 moles Isophthalic acid: 10 moles Fumaric acid: 10 moles Ethylene glycol: 50 moles • Propylene glycol: 50 moles The ester group concentration of the obtained amorphous polyester resin (3) was 45.0% by mass.

[0139] In the preparation of amorphous polyester resin dispersion (1), amorphous polyester resin dispersion (3) with a solid content of 20% by mass was obtained in the same manner as in the preparation of amorphous polyester resin dispersion (1), except that amorphous polyester resin (1) was replaced with amorphous polyester resin (3).

[0140] [Preparation of amorphous polyester resin dispersion (4) (PES4)] In the preparation of amorphous polyester (1), amorphous polyester resin (4) was obtained in the same manner as described below, except that the preparation of the materials was changed. Terephthalic acid: 100 moles • Ethylene glycol: 60 moles • Propylene glycol: 5 moles • Bisphenol A propylene oxide 2 molar adduct: 35 molar parts The ester group concentration of the obtained amorphous polyester resin (4) was 30.0% by mass.

[0141] In the preparation of amorphous polyester resin dispersion (1), amorphous polyester resin dispersion (4) with a solid content of 20% by mass was obtained in the same manner as in the preparation of amorphous polyester resin dispersion (1), except that amorphous polyester resin (1) was replaced with amorphous polyester resin (4).

[0142] [Preparation of amorphous polyester resin dispersion (5) (PES5)] In the preparation of amorphous polyester (1), amorphous polyester resin (5) was obtained in the same manner as described below, except that the preparation of the materials was changed. Terephthalic acid: 100 moles • Ethylene glycol: 5 moles • Propylene glycol: 5 moles • Neopentyl glycol: 40 moles • Bisphenol A propylene oxide 2 molar adduct: 50 molar parts The ester group concentration of the obtained amorphous polyester resin (5) was 25.0% by mass.

[0143] In the preparation of amorphous polyester resin dispersion (1), an amorphous polyester resin dispersion (5) with a solid content of 20% by mass was obtained in the same manner as in the preparation of amorphous polyester resin dispersion (1), except that amorphous polyester resin (1) was replaced with amorphous polyester resin (5).

[0144] [Preparation of amorphous polyester resin dispersion (6) (PES6)] In the preparation of amorphous polyester (1), amorphous polyester resin (6) was obtained in the same manner as described below, except that the preparation of the materials was changed. Terephthalic acid: 70 moles • Adipic acid: 25 moles Fumaric acid: 5 moles • Ethylene glycol: 35 moles • Propylene glycol: 30 moles • Bisphenol A propylene oxide 2 molar adduct: 15 moles • Bisphenol A ethylene oxide 2 molar adduct: 20 moles The ester group concentration of the obtained amorphous polyester resin (6) was 31.0% by mass.

[0145] In the preparation of amorphous polyester resin dispersion (1), amorphous polyester resin dispersion (6) with a solid content of 20% by mass was obtained in the same manner as in the preparation of amorphous polyester resin dispersion (1), except that amorphous polyester resin (1) was replaced with amorphous polyester resin (6).

[0146] [Preparation of amorphous polyester resin dispersion (7) (PES7)] In the preparation of amorphous polyester (1), amorphous polyester resin (7) was obtained in the same manner as described below, except that the preparation of the materials was changed. Terephthalic acid: 68 molar parts Isophthalic acid: 20 moles • Adipic acid: 12 moles • Ethylene glycol: 40 moles • Propylene glycol: 40 moles • Neopentyl glycol: 20 moles The ester group concentration of the obtained amorphous polyester resin (7) was 43.0% by mass.

[0147] In the preparation of amorphous polyester resin dispersion (1), an amorphous polyester resin dispersion (7) with a solid content of 20% by mass was obtained in the same manner as in the preparation of amorphous polyester resin dispersion (1), except that amorphous polyester resin (1) was replaced with amorphous polyester resin (7).

[0148] [Preparation of amorphous polyester resin dispersion (X)] Terephthalic acid: 80 moles Dodecenyl succinate: 20 moles • Propylene glycol: 10 moles • Bisphenol A propylene oxide 2 molar adduct: 80 molar parts • Bisphenol A ethylene oxide 2 molar adduct: 10 moles The above materials were placed in a reaction vessel equipped with a stirrer, nitrogen inlet tube, temperature sensor, and rectification column, and the temperature was raised to 190°C over 1 hour. 1.2 parts of dibutyltin oxide were added for every 100 parts of the above materials. The temperature was raised to 240°C over 6 hours while distilling off the generated water, and then the dehydration condensation reaction was continued at 240°C for 3 hours. After cooling, amorphous polyester resin (X) was obtained. The ester group concentration of amorphous polyester resin (X) was 18.7% by mass.

[0149] In the preparation of amorphous polyester resin dispersion (1), an amorphous polyester resin dispersion (X) with a solid content of 20% by mass was obtained in the same manner as in the preparation of amorphous polyester resin dispersion (1), except that amorphous polyester resin (1) was replaced with amorphous polyester resin (X).

[0150] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B2)] <<Emulsion (2)>> • Styrene: 40 units n-butyl acrylate: 21.5 parts Ethyl acrylate: 37 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare the emulsified liquid (2). In the preparation of styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (2) with a solid content concentration of 20% by mass was obtained in the same manner as in the preparation of emulsion (1), except that emulsion (2) was replaced with emulsion (1). The ester group concentration of the obtained resin particles was 20.0% by mass.

[0151] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B3)] <<Emulsion (3)>> • Styrene: 50 units n-butyl acrylate: 36 parts • 2-ethylhexyl acrylate: 12.5 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare the emulsified liquid (3). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (3) with a solid content of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (3). The ester group concentration of the obtained resin particles was 13.0% by mass.

[0152] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B4)] <<Emulsion (4)>> Styrene: 40.6 parts n-butyl acrylate: 58.5 parts • Divinylbenzene: 0.9 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified liquid (4). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (4) with a solid content concentration of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (4). The ester group concentration of the obtained resin particles was 17.0% by mass.

[0153] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B5)] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the amount of anionic surfactant (eleminol MON-2) added to the reaction vessel was changed from 0.4 parts to 1.2 parts, except that the procedure was the same to obtain a styrene-(meth)acrylate copolymer particle dispersion (5) with a solid content of 20% by mass. The ester group concentration of the obtained resin particles was 17.0% by mass.

[0154] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B6)] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the amount of anionic surfactant (eleminol MON-2) added to the reaction vessel was changed from 0.4 parts to 0.1 parts, except that the procedure was the same to obtain a styrene-(meth)acrylate copolymer particle dispersion (6) with a solid content of 20% by mass. The ester group concentration of the obtained resin particles was 17.0% by mass.

[0155] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B7)] <<Emulsion (7)>> • Styrene: 45 units n-butyl acrylate: 10 parts • 2-ethylhexyl acrylate: 43.5 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified solution (7). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (7) with a solid content of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (7). The ester group concentration of the obtained resin particles was 11.7% by mass.

[0156] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B8)] <<Emulsion (8)>> Styrene: 48.5 parts n-butyl acrylate: 39 parts • 2-ethylhexyl acrylate: 11 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified liquid (8). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (8) with a solid content concentration of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (8). The ester group concentration of the obtained resin particles was 13.6% by mass.

[0157] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B9)] <<Emulsion (9)>> • Styrene: 40 units n-butyl acrylate: 20.5 parts Ethyl acrylate: 38 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified solution (9). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (9) with a solid content concentration of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (9). The ester group concentration of the obtained resin particles was 20.1% by mass.

[0158] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B10)] <<Emulsion (10)>> • Styrene: 37 parts n-butyl acrylate: 15 parts Ethyl acrylate: 46.5 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified solution (10). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (10) with a solid content concentration of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (10). The ester group concentration of the obtained resin particles was 21.7% by mass.

[0159] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B11)] <<Emulsion (11)>> Styrene: 41.5 parts n-butyl acrylate: 58.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified liquid (11). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (11) with a solid content concentration of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (11). The ester group concentration of the obtained resin particles was 17.0% by mass.

[0160] [Preparation of (meth)acrylate resin particle dispersion (B12)] <<Emulsion (12)>> Dodecyl acrylate: 98.5 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified solution (12). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), an (meth)acrylate copolymer particle dispersion (12) with a solid content concentration of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (12). The ester group concentration of the obtained resin particles was 15.3% by mass.

[0161] [Preparation of Styrene-(meth)acrylate copolymer particle dispersion (B13)] <<Emulsion (13)>> • Styrene: 61 parts • n-butyl acrylate: 37.5 parts • Divinylbenzene: 1.5 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts • Ion-exchanged water: 98.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified solution (13). In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), a styrene-(meth)acrylate copolymer particle dispersion (13) with a solid content concentration of 20% by mass was obtained in the same manner as in the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), except that emulsion (1) was replaced with emulsion (13). The ester group concentration of the obtained resin particles was 10.9.

[0162] [Preparation of release agent particle dispersion (2)] In the preparation of the mold release agent particle dispersion (1), the paraffin wax w1 was replaced with ester wax w2 (product name: WEP-3, manufactured by NOF Corporation, ester group concentration: 6.6% by mass, melting point: 72°C), except that the same procedure was followed to obtain a mold release agent particle dispersion (2) with a solid content of 20% by mass.

[0163] [Preparation of mold release agent particle dispersion (3)] In the preparation of the release agent particle dispersion (1), the paraffin wax w1 was replaced with ester wax w3 (product name: WEP-6, manufactured by NOF Corporation, ester group concentration: 14.4% by mass, melting point: 77°C), and the same procedure was followed to obtain a release agent particle dispersion (3) with a solid content of 20% by mass.

[0164] [Preparation of mold release agent particle dispersion (4)] In the preparation of the mold release agent particle dispersion (1), a mold release agent particle dispersion (4) with a solid content of 20% by mass was obtained in the same manner as in the preparation of the mold release agent particle dispersion (1), except that paraffin wax w1 was replaced with paraffin wax w4 (product name: SP-1039, manufactured by Nippon Seiro Co., Ltd., ester group concentration: 0% by mass, melting point: 60°C).

[0165] [Preparation of mold release agent particle dispersion (5)] In the preparation of the release agent particle dispersion (1), the paraffin wax w1 was replaced with polyethylene wax w5 (product name: High Wax 420P, manufactured by Mitsui Chemicals, Inc., ester group concentration: 0% by mass, melting point: 116°C), except that the same procedure was followed to obtain a release agent particle dispersion (5) with a solid content of 20% by mass.

[0166] [Preparation of Release Agent Particle Dispersion (6)] In the preparation of the release agent particle dispersion (1), except that paraffin wax w1 was changed to fatty acid amide wax w6 (trade name: Fatty Acid Amide S, manufactured by Kao Corporation, ester group concentration: 0% by mass, melting point: 100 °C), a release agent particle dispersion (6) with a solid content of 20% by mass was obtained in the same manner.

[0167] [Preparation of Release Agent Particle Dispersion (7)] In the preparation of the release agent particle dispersion (1), except that paraffin wax w1 was changed to polyethylene wax w7 (trade name: Polywax 625, manufactured by NuCera Solutions, ester group concentration: 0% by mass, melting point: 99 °C), a release agent particle dispersion (7) with a solid content of 20% by mass was obtained in the same manner.

[0168] <Method for Measuring Ester Group Concentration> The ester group concentration can be calculated from the number of ester groups [-C(=O)O-] in the resin or compound, and specifically, it is represented by the following formula. Ester group concentration (% by mass) = [(N × 44) / number average molecular weight] × 100 Here, N is the average number of ester groups per molecule, and 44 is the formula weight of the ester group [-C(=O)O-]. It was calculated by determining the monomer composition or chemical structure of the compound and the number of ester groups by nuclear magnetic resonance spectrum (NMR), etc.

[0169] <Evaluation of Fixing Property and Concentration Unevenness Suppression Property under High Humidity Environment> In an environment of 25 °C / 80% RH, evaluation was performed using Apeos C7070 (manufactured by Fujifilm Business Innovation Corp.) with paper (GR100; manufactured by Fujifilm Business Innovation Corp.) left standing for one week after opening. Specifically, 100 consecutive prints of a 20 mm × 20 mm solid image were made, and the presence or absence of poor fixing was visually judged. A: No poor fixing occurred in all 100 sheets B: Minor poor fixing occurred in 3 sheets or less out of 100 sheets C: Fixing failure occurred on 4 out of 100 sheets.

[0170] Furthermore, for image defects, 10,000 image patterns were printed in a vertical A4 size, with solid strips of image material arranged in an environment of 25°C / 80%RH. The subsequent full-blend halftone (30%) images were then evaluated. In the full-blend halftone (30%) images, the difference between the average of five points of image density measured at locations corresponding to the previously printed strips and the average of five points of image density measured at locations corresponding to the non-image areas of the strips was evaluated. Image density was measured using an X-Rite 404 (manufactured by X-Rite Corporation). A: The density difference between the image area and the non-image area is less than 0.02, indicating that a uniform image has been obtained. B: The density difference between the image area and the non-image area is between 0.02 and 0.05, meaning the unevenness is barely noticeable. C: The density difference between the image area and the non-image area is between 0.05 and 0.10, which is within an acceptable level. D: The density difference between the image area and the non-image area is 0.10 or greater, which is an unacceptable level.

[0171] [Table 1]

[0172] As shown in Table 1, the electrostatic image developing toner of the example demonstrated superior suppression of density unevenness in high-humidity environments compared to the electrostatic image developing toner of the comparative example.

[0173] (((1))) A toner for developing electrostatic images, comprising toner particles containing a binder resin, a release agent, and resin particles forming domains inside the toner particles, wherein the binder resin contains a polyester resin, the average ester group concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less, and when the ester group concentration of the resin particles is c2, the value of c2 / c1 is 0.30 or more and 0.70 or less. (((2))) The toner for developing electrostatic images according to (((1))), wherein the content of the release agent is 1% by mass or more and 10% by mass or less with respect to the total mass of the toner particles. (((3))) The electrostatic image developing toner according to (((1))) or (((2))), wherein when the content of the mold release agent in the toner particles is Ww and the content of the resin particles is Wb, the value of Wb / Ww is 0.3 or more and 5.0 or less. (((4))) The toner for developing electrostatic images according to any one of (((1))) to (((3))), wherein the average equivalent circle diameter of the domains formed by the resin particles is 50 nm or more and 300 nm or less. (((5))) The toner for developing electrostatic images according to any one of (((1))) to (((4))), wherein the melting point of the release agent is 60°C or more and 120°C or less. (((6))) The electrostatic image developing toner according to any one of (((1))) to (((5))) wherein the resin particles are styrene (meth)acrylic resin particles. (((7))) The electrostatic image developing toner according to any one of (((1))) to (((6))) wherein the resin particles are crosslinked resin particles. (((8))) The toner for developing electrostatic images according to any one of (((1))) to (((7))), wherein the tetrahydrofuran insoluble content of the resin particles is 80% by mass or more. (((9))) The toner for developing electrostatic images according to any one of (((1))) to (((8))) wherein the release agent comprises at least one selected from the group consisting of hydrocarbon waxes and ester waxes. (((10))) The electrostatic image developing toner according to any one of (((1))) to (((9))), wherein the ester group concentration c3 of the release agent is 15% by mass or less. A electrostatic image developer containing a toner for developing electrostatic images as described in any one of (((11))) (((1))) to (((10))). A toner cartridge that contains the electrostatic image developing toner described in any one of (((12))) (((1))) to (((10))) and is attached to and detached from an image forming apparatus. A process cartridge that is attached to and detached from an image forming apparatus, comprising a developing device that contains the electrostatic image developer described in (((13))) (((11))) and develops an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer. (((14))) An image forming apparatus comprising: an image holder; a charging device for charging the surface of the image holder; an electrostatic image forming device for forming an electrostatic image on the charged surface of the image holder; a developing device for containing the electrostatic image developer described in (((11))) and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer; a transfer device for transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing device for fixing the toner image transferred to the surface of the recording medium. (((15))) An image forming method comprising: a charging step of charging the surface of an image holder; a static charge image forming step of forming a static charge image on the charged surface of the image holder; a developing step of developing the static charge image formed on the surface of the image holder as a toner image using the static charge image developer described in (((11))); a transfer step of transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0174] According to the invention of (((1))) or (((9))), a toner for developing electrostatic images is provided that has toner particles comprising a binder resin, a release agent, and resin particles forming domains inside the toner particles, wherein the binder resin comprises a polyester resin, and the average ester group concentration c1 of the binder resin is less than 25% by mass or greater than 48% by mass, or, when the ester group concentration of the resin particles is c2, the value of c2 / c1 is less than 0.30 or greater than 0.70, compared to the case where the binder resin comprises a polyester resin, and the average ester group concentration c1 of the binder resin is less than 25% by mass or greater than 48% by mass, or the value of c2 / c1 is less than 0.30 or greater than 0.70. According to the invention of (((2))), a toner for developing electrostatic images is provided that is superior in suppressing density unevenness in a high-humidity environment compared to cases where the content of the release agent is less than 1% by mass or more than 10% by mass relative to the total mass of the toner particles. According to the invention of (((3))), when the content of the mold release agent in the toner particles is Ww and the content of the resin particles is Wb, a toner for electrostatic image development is provided that is superior in suppressing density unevenness in a high humidity environment compared to cases where the value of Wb / Ww is less than 0.3 or greater than 5.0. According to the invention of (((4))), a toner for developing electrostatic images is provided that is superior in suppressing density unevenness in a high-humidity environment compared to cases where the average equivalent circle diameter of the domains formed by the resin particles is less than 50 nm or greater than 300 nm. According to the invention of (((5))), a toner for electrostatic image development is provided that is superior in suppressing density unevenness in a high humidity environment compared to cases where the melting point of the release agent is less than 60°C or more than 120°C. According to the invention of (((6))), a toner for developing electrostatic images is provided that is superior in suppressing density unevenness in a high-humidity environment compared to the case in which the resin particles are polyester resin particles. According to the invention of (((7))), a toner for developing electrostatic images is provided that is superior in suppressing density unevenness in a high-humidity environment compared to the case in which the resin particles are resin particles that do not have a crosslinking structure. According to the invention of (((8))), a toner for developing electrostatic images is provided that is superior in suppressing density unevenness in a high-humidity environment compared to the case in which the tetrahydrofuran insoluble content of the resin particles is less than 80% by mass. According to the invention of (((10))), a toner for developing electrostatic images is provided that is superior in suppressing density unevenness in a high humidity environment compared to the case in which the ester group concentration c3 of the release agent is greater than 15% by mass. According to the invention according to ((11)), ((12)), ((13)), ((14)) or ((15)), there are toner particles containing a binder resin, a release agent, and resin particles forming domains inside the toner particles, the binder resin contains a polyester resin, the average ester group concentration c1 of the binder resin is less than 25% by mass or more than 48% by mass, or when the ester group concentration of the resin particles is c2, the value of c2 / c1 is less than 0.30 or more than 0.70. Compared with the case of using an electrostatic charge image developing toner, an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus or an image forming method excellent in density unevenness suppression in a high humidity environment is provided.

Explanation of Signs

[0175] 1Y, 1M, 1C, 1K Photoconductor (an example of an image holding member) 2Y, 2M, 2C, 2K Charging roll (an example of a charging device) 3 Exposure device (an example of an electrostatic charge image forming device) 3Y, 3M, 3C, 3K Laser beam 4Y, 4M, 4C, 4K Developing device (an example of a developing device) 5Y, 5M, 5C, 5K Primary transfer roll (an example of a primary transfer device) 6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of a cleaning device) 8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt (an example of an intermediate transfer member) 22 Driving roll 24 Support roll 26 Secondary transfer roll (an example of a secondary transfer device) 28 Fixing device (an example of a fixing device) 30 Intermediate transfer member cleaning device 107 Photoconductor (an example of an image holding member) 108 Charging roll (an example of a charging device) 109 Exposure device (an example of an electrostatic charge image forming device) 111 Developing device (an example of a developing device) 112 Transfer device (an example of a transfer device) 113 Photoconductor Cleaning Device (Example of a cleaning device) 115 Fixing device (an example of a fixing device) 116 Mounting Rail 118 Aperture for exposure 117 cabinets 200 Process Cartridges 300 Recording paper (an example of a recording medium) P Recording paper (an example of a recording medium)

Claims

1. The toner particles include a binder resin, a release agent, and resin particles that form domains within the toner particles. The aforementioned binder resin includes a polyester resin, The average ester group concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less. When the ester group concentration of the resin particles is c2, the value of c2 / c1 is 0.30 or more and 0.70 or less. Toner for developing electrostatic images.

2. The toner for developing electrostatic images according to claim 1, wherein the content of the release agent is 1% by mass or more and 10% by mass or less with respect to the total mass of the toner particles.

3. The electrostatic image developing toner according to claim 1, wherein, when the content of the mold release agent in the toner particles is Ww and the content of the resin particles is Wb, the value of Wb / Ww is 0.3 or more and 5.0 or less.

4. The toner for developing electrostatic images according to claim 1, wherein the average circular equivalent diameter of the domains formed by the resin particles is 50 nm or more and 300 nm or less.

5. The toner for developing electrostatic images according to claim 1, wherein the melting point of the release agent is 60°C or higher and 120°C or lower.

6. The electrostatic image developing toner according to claim 1, wherein the resin particles are styrene (meth)acrylic resin particles.

7. The electrostatic image developing toner according to claim 1, wherein the resin particles are crosslinked resin particles.

8. The toner for developing electrostatic images according to claim 1, wherein the tetrahydrofuran-insoluble portion of the resin particles is 80% by mass or more.

9. The toner for developing electrostatic images according to claim 1, wherein the release agent comprises at least one selected from the group consisting of hydrocarbon waxes and ester waxes.

10. The toner for developing electrostatic images according to claim 1, wherein the ester group concentration c3 of the release agent is 15% by mass or less.

11. A electrostatic image developer comprising the electrostatic image developing toner according to any one of claims 1 to 10.

12. A toner cartridge for containing the electrostatic image developing toner according to any one of claims 1 to 10, which is attached to and detached from an image forming apparatus.

13. A process cartridge that is attached to and detached from an image forming apparatus, comprising a developing apparatus that contains the electrostatic image developer described in claim 11 and develops an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer.

14. Image holder and, A charging device for charging the surface of the image holder, A static charge image forming apparatus for forming a static charge image on the surface of the charged image holder, A developing apparatus comprising: containing the electrostatic image developer described in claim 11, and developing an electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer; A transfer device for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, The system includes a fixing device for fixing the toner image transferred to the surface of the recording medium. Image forming apparatus.

15. A charging step in which the surface of the image holder is charged, A step of forming an electrostatic image on the surface of the charged image holder, A developing step of developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer according to claim 11, A transfer step of transferring the toner image formed on the surface of the image holder to the surface of the recording medium, The process includes fixing the toner image transferred to the surface of the recording medium. Image forming method.

Images