Method for producing toner for developing electrostatic images

Abstract

A method for producing a toner for developing electrostatic images that suppresses the occurrence of uneven image density is provided. [Solution] A method for producing a toner for developing electrostatic images includes the steps of: aggregating amorphous resin particles (1) in a resin particle dispersion containing amorphous resin particles (1) obtained by melt-mixing an amorphous resin and adding an aqueous medium to granulate the particles, thereby forming first aggregated particles; adhering amorphous resin particles (2) to the surfaces of the first aggregated particles in a resin particle dispersion containing the first aggregated particles and amorphous resin particles (2) obtained by dissolving and mixing an amorphous resin and an organic solvent, and adding an aqueous medium to granulate the particles; and heating the dispersion containing the second aggregated particles to fuse and coalesce the second aggregated particles to form toner particles, wherein the toner particles contain sulfur element, and the content of sulfur element contained in the toner particles is 0.05% by mass or more and 0.20% by mass or less relative to the mass of the toner particles.

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a toner for developing electrostatic images. [Background technology]

[0002] Patent Document 1 discloses a method for producing a toner for electrophotography, which includes a step (1) of aggregating resin particles in a resin particle dispersion to obtain a dispersion of aggregated particles, a step (2) of adding a resin microparticle dispersion to the dispersion of aggregated particles to obtain a dispersion of aggregated particles with resin microparticles attached thereto, and a step (3) of coalescing the aggregated particles with resin microparticles attached thereto in the dispersion of aggregated particles with resin microparticles attached thereto, wherein the resin particle dispersion is obtained by a method including a step of dispersing a resin containing an amorphous polyester and a crystalline polyester in an aqueous medium in one reaction vessel, and the resin microparticle dispersion is obtained by a method including a step of mixing a resin containing 80% by weight or more of amorphous polyester with an organic solvent, and then adding an aqueous medium to disperse the mixture.

[0003] Patent Document 2 discloses a toner having core particles containing at least a binder resin, a colorant, and a release agent, and a coating layer that coats the core particles, wherein the coating layer is formed by adhering resin fine particles to the surface of the core particles, wherein the difference (Tg2-Tg1) between the glass transition temperature Tg1 of the core particles and the glass transition temperature Tg2 of the resin fine particles is 5°C to 40°C, the resin fine particles are composed of a resin that contains at least a carboxyl group and a sulfonic acid group, and the sulfur element contained in the coating layer is 0.005% by mass to 0.050% by mass of the toner particles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-081241 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-181802 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a method for producing a toner for developing electrostatic images that suppresses the occurrence of uneven image density. [Means for solving the problem]

[0006] Specific means for solving the above problems include the following aspects. <1> a step of aggregating the amorphous resin particles (1) in a resin particle dispersion liquid containing amorphous resin particles (1) obtained by melt-mixing an amorphous resin and adding an aqueous medium to the amorphous resin to form first aggregated particles; forming second aggregated particles by adhering the amorphous resin particles (2) to the surfaces of the first aggregated particles in a resin particle dispersion containing the first aggregated particles and amorphous resin particles (2) obtained by dissolving and mixing an amorphous resin and an organic solvent, and adding an aqueous medium to the amorphous resin particles (2) to granulate the particles; and heating the dispersion liquid containing the second aggregated particles to fuse and coalesce the second aggregated particles to form toner particles, the toner particles contain sulfur element, and the content of the sulfur element contained in the toner particles is 0.05% by mass or more and 0.20% by mass or less with respect to the mass of the toner particles; A method for producing a toner for developing electrostatic images. <2> the amorphous resin particles (1) contain elemental sulfur, the value obtained by dividing the content of the sulfur element contained in the toner particles (mass ratio to the mass of the toner particles) by the content of the sulfur element contained in the amorphous resin particles (1) (mass ratio of the amorphous resin particles (1) to the mass of the amorphous resin) is 1 or less; <1> 10. A method for producing the toner for developing electrostatic images according to claim 9. <3> the toner particles contain a nitrogen element, the value (ppm / mass%) obtained by dividing the nitrogen element content (ppm) on the surface of the toner particles by the sulfur element content (mass%) contained in the toner particles is 50 or less; <1> or <2> 10. A method for producing the toner for developing electrostatic images according to claim 9. <4> <1> ~ <3> 10. A toner for developing electrostatic images, which is produced by the method for producing a toner for developing electrostatic images according to any one of claims 1 to 9. <5> <4> 10. An electrostatic image developer comprising the toner for developing electrostatic images according to claim 1. <6> <4> The toner for developing electrostatic images according to claim 1 is contained in the container. A toner cartridge that is detachably attached to an image forming device. <7> <5> a developing device that contains the electrostatic image developer according to claim 1 and develops an electrostatic image formed on the surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge is detachably mounted in an image forming apparatus. <8> an image carrier; a charging device that charges the surface of the image carrier; an electrostatic image forming device for forming an electrostatic image on the charged surface of the image carrier; <5> a developing device that contains the electrostatic image developer according to claim 1 and develops the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer; a transfer device that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing device for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising: <9> a charging step of charging the surface of the image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; <5> a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to claim 1; a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; An image forming method comprising the steps of: [Effects of the Invention]

[0007] <1> According to the present invention, a manufacturing method for manufacturing a toner for developing electrostatic images is provided that suppresses the occurrence of image density unevenness compared to manufacturing methods in which the content of sulfur element contained in the toner particles is less than 0.05% by mass or more than 0.20% by mass relative to the mass of the toner particles. <2> According to the present invention, a method for producing a toner for developing electrostatic images is provided that suppresses the occurrence of uneven image density compared to a production method in which the value obtained by dividing the content of sulfur element contained in the toner particles by the content of sulfur element contained in the amorphous resin particles (1) exceeds 1. <3> According to the present invention, a manufacturing method for manufacturing a toner for developing electrostatic images is provided that suppresses the occurrence of uneven image density compared to a manufacturing method in which the value (ppm / mass%) obtained by dividing the nitrogen element content (ppm) on the surface of the toner particles by the sulfur element content (mass%) contained in the toner particles exceeds 50. <4> According to the present invention, a toner for developing electrostatic images is provided which suppresses the occurrence of uneven image density compared to a toner for developing electrostatic images in which the content of sulfur element contained in the toner particles is less than 0.05% by mass or more than 0.20% by mass relative to the mass of the toner particles. <5> According to the present invention, an electrostatic image developer is provided which suppresses the occurrence of image density unevenness compared to an electrostatic image developer containing an electrostatic image developing toner in which the content of sulfur element contained in the toner particles is less than 0.05% by mass or more than 0.20% by mass relative to the mass of the toner particles. <6> According to the present invention, a toner cartridge is provided that suppresses the occurrence of image density unevenness compared to a toner cartridge that contains electrostatic image developing toner in which the content of sulfur element contained in the toner particles is less than 0.05% by mass or more than 0.20% by mass relative to the mass of the toner particles. <7> According to the present invention, a process cartridge is provided that suppresses the occurrence of uneven image density compared to a process cartridge that accommodates an electrostatic image developer containing a toner for developing electrostatic images, the toner particles of which contain less than 0.05% by mass or more than 0.20% by mass of sulfur element relative to the mass of the toner particles. <8> According to the present invention, an image forming apparatus is provided that suppresses the occurrence of image density unevenness compared to an image forming apparatus that contains an electrostatic image developer containing a toner for developing electrostatic images, the toner particles of which contain less than 0.05% by mass or more than 0.20% by mass of sulfur element, relative to the mass of the toner particles. <9> According to the present invention, an image forming method is provided which suppresses the occurrence of image density unevenness compared to an image forming method using an electrostatic image developer containing an electrostatic image developing toner in which the content of sulfur element contained in the toner particles is less than 0.05 mass % or more than 0.20 mass % relative to the mass of the toner particles. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram illustrating an example of a process cartridge that is detachably mounted to an image forming apparatus according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes embodiments of the present disclosure. These descriptions and examples are intended to illustrate the embodiments and are not intended to limit the scope of the embodiments.

[0010] In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

[0011] In the present disclosure, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" means that it may be only A, only B, or a combination of A and B.

[0012] In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0013] When embodiments of the present disclosure are described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these.

[0014] In the present disclosure, each component may contain multiple corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the composition may contain multiple types of particles corresponding to each component. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0015] In the present disclosure, "(meth)acrylic" is an expression that includes both acrylic and methacrylic, and "(meth)acrylate" is an expression that includes both acrylate and methacrylate.

[0016] In this disclosure, "developer" refers to "electrostatic image developer," "carrier" refers to "electrostatic image developing carrier," and "toner" refers to "electrostatic image developing toner."

[0017] In the present disclosure, a method for producing toner particles by aggregating and coalescing material particles in a dispersion medium is referred to as an EA (Emulsion Aggregation) method.

[0018] <Method of manufacturing toner for developing electrostatic images> The toner manufacturing method of the present disclosure is a toner manufacturing method that includes manufacturing toner particles by the EA method, and includes the following first aggregation step, second aggregation step, and coalescence step.

[0019] First aggregation step: A step of forming first aggregated particles by aggregating amorphous resin particles (1) in a resin particle dispersion containing amorphous resin particles (1) obtained by melt-mixing an amorphous resin and adding an aqueous medium to granulate the amorphous resin. Second aggregation step: A step of forming second aggregated particles by adhering amorphous resin particles (2) to the surfaces of the first aggregated particles in a resin particle dispersion liquid containing the first aggregated particles and amorphous resin particles (2) obtained by dissolving and mixing an amorphous resin and an organic solvent, and adding an aqueous medium to the mixture to granulate the particles. Coalescence step: A step of heating the dispersion liquid containing the second aggregated particles to fuse and coalesce the second aggregated particles to form toner particles.

[0020] The first aggregation step is a step for forming the core of the toner particles having a core-shell structure. The second aggregation step is a step for forming the shell of the toner particles having a core-shell structure. By going through the first aggregation step, the second aggregation step, and the coalescence step, the toner particles having a core-shell structure can be produced.

[0021] Granulation of the amorphous resin particles (1) is carried out in the absence of an organic solvent, i.e., substantially no organic solvent is used, or in the presence of an organic solvent in an amount of 10% by mass or less based on the resin. Granulation of the amorphous resin particles (1) is preferably carried out in the absence of an organic solvent. An organic solvent is used for granulating the amorphous resin particles (2).

[0022] The toner manufacturing method according to this embodiment includes a first aggregation step and a second aggregation step, and the sulfur content of the toner particles is 0.05% by mass or more and 0.20% by mass or less relative to the mass of the toner particles. When an image is formed using a toner containing sulfur, image density unevenness occurs due to charge injection in a high-temperature, high-humidity environment. However, the toner manufacturing method according to this embodiment produces a toner that suppresses the occurrence of image density unevenness. The mechanism behind this is presumed to be as follows.

[0023] Resin particle dispersions used in chemical toner production methods such as the EA method are generally resin particle dispersions containing resin particles obtained by dissolving and mixing a resin and an organic solvent and then adding an aqueous medium to granulate the mixture (i.e., resin particle dispersions produced by a phase inversion emulsification method using an organic solvent), or resin particle dispersions containing resin particles obtained by melt-mixing a resin and then adding an aqueous medium to granulate the mixture (i.e., resin particle dispersions produced by a forced emulsification method under high-pressure, high-temperature conditions). In the granulation of the amorphous resin particles (2), since the organic solvent is hydrophobic, the dissolved mixture of the amorphous resin and the organic solvent tends to be hydrophobic, and hydrophilic groups tend to be present on the surface of the amorphous resin particles (2) in the resin particle dispersion granulated by adding an aqueous medium. On the other hand, in the granulation of the amorphous resin particles (1) in this embodiment, since no organic solvent is present, the molten mixture of the amorphous resin is less likely to become hydrophobic, and hydrophilic groups are more likely to be present inside the amorphous resin particles (1) in the resin particle dispersion granulated by adding an aqueous medium. Therefore, toner particles with a core-shell structure, in which amorphous resin particles (1) are used to form the core and amorphous resin particles (2) to form the shell, tend to have hydrophilic groups on the surface and inside the toner particles. When these toner particles are placed in a high-temperature, high-humidity environment, it is presumed that moisture adhering to the surface of the toner particles migrates and remains inside the toner via the hydrophilic groups of the amorphous resin particles (2), the sulfur elements in the toner particles, and the hydrophilic groups of the amorphous resin particles (1) inside the toner particles. As a result, it is presumed that charge injection into the toner is suppressed, and image density unevenness is suppressed.

[0024] If the content of elemental sulfur contained in the toner particles is less than 0.05% by mass relative to the mass of the toner particles, moisture is less likely to migrate into the toner particles, and the amount of moisture adsorbed on the surface of the toner particles increases relatively, which may lead to uneven image density due to charge injection. From the viewpoint of suppressing this phenomenon, the content of elemental sulfur contained in the toner particles is 0.05% by mass or more, preferably 0.08% by mass or more, and more preferably 0.10% by mass or more. If the content of elemental sulfur contained in the toner particles exceeds 0.20% by mass relative to the mass of the toner particles, excess moisture remains inside the toner particles, making it difficult to suppress charge injection into the toner. From the viewpoint of suppressing this phenomenon, the content of elemental sulfur contained in the toner particles is 0.20% by mass or less, preferably 0.18% by mass or less, and more preferably 0.15% by mass or less.

[0025] The sulfur content of the toner particles can be controlled by using an appropriate amount of a material containing sulfur when granulating the raw material particles of the toner particles and / or when granulating the toner particles. Examples of materials containing sulfur include surfactants, binder resins, and other components that themselves contain sulfur as chain transfer agents for resins, and surfactants containing sulfur are preferred. Examples of surfactants containing sulfur atoms include sulfonate surfactants.

[0026] The content of the sulfur element contained in the toner particles is determined by the following measurement method. When the toner contains an external additive, the external additive is removed from the toner particles by ultrasonic treatment. Specifically, 1% by mass of the toner is added to a 10% by mass aqueous solution of ethanol, and ultrasonic vibrations at a power of 20 W and a frequency of 20 kHz are applied for 30 minutes to remove the external additive from the toner particles, followed by centrifugal separation and drying to obtain toner particles. 0.130 g of toner particles are precisely weighed and molded into a disk shape. The molded product is used as a sample for qualitative and quantitative total elemental analysis using X-ray fluorescence analysis to determine the sulfur element content (mass%). X-ray fluorescence analysis is performed using the following equipment and conditions. Scanning X-ray fluorescence analyzer: ZSX Primus II, Rigaku Corporation X-ray output: 40mA~70mA ·Measurement area: diameter 10mm Measurement time: 15 minutes When the peak of elemental sulfur overlaps with the peak of other elements, further analysis is carried out by ICP emission spectroscopy and / or atomic absorption spectroscopy to determine the content (mass %) of elemental sulfur.

[0027] In the toner manufacturing method of the present disclosure, it is preferable that the amorphous resin particles (1) contain sulfur element, and the content of sulfur element contained in the amorphous resin particles (1) is 0.10 mass % or more and 0.25 mass % or less, relative to the mass of the amorphous resin of the amorphous resin particles (1). When the content of elemental sulfur contained in the amorphous resin particles (1) is 0.10% by mass or more, it is presumed that when the amorphous resin is melt-mixed and an aqueous medium is added to granulate the particles, the elemental sulfur is kneaded into the interior of the amorphous resin particles (1) together with hydrophilic groups, which makes it easier for moisture to remain inside the toner particles and makes it easier to suppress charge injection into the toner. From this viewpoint, the content of elemental sulfur contained in the amorphous resin particles (1) is more preferably 0.11% by mass or more, and even more preferably 0.12% by mass or more. When the content of elemental sulfur contained in the amorphous resin particles (1) is 0.25% by mass or less, an appropriate amount of elemental sulfur is kneaded into the interior of the amorphous resin particles (1) together with hydrophilic groups, which is presumably to facilitate retention of moisture inside the toner particles and facilitate suppression of charge injection into the toner. From this viewpoint, the content of elemental sulfur contained in the amorphous resin particles (1) is more preferably 0.20% by mass or less, and even more preferably 0.16% by mass or less.

[0028] The content of elemental sulfur contained in the amorphous resin particles 1 can be controlled by using an appropriate amount of a material containing elemental sulfur when granulating the amorphous resin particles 1. Examples of the material containing elemental sulfur include surfactants, such as sulfonate surfactants.

[0029] In the toner manufacturing method of the present disclosure, the content of sulfur element contained in the amorphous resin particles (2) is preferably 0.10 mass % or less relative to the mass of the amorphous resin of the amorphous resin particles (2), from the viewpoint of facilitating retention of moisture inside the toner. The lower the content, the better, and ideally 0 mass %.

[0030] The sulfur element content in the amorphous resin particles (2) can be reduced to 0.10% by mass or less by not using any material containing sulfur element when granulating the amorphous resin particles (2), or by removing any used material by washing, etc. Examples of materials containing sulfur element include sulfonate surfactants.

[0031] The content of elemental sulfur contained in the amorphous resin particles (1) and the content of elemental sulfur contained in the amorphous resin particles (2) are each determined by the following measurement method. 5 mL of the resin particle dispersion is subjected to solid-liquid separation. The separated resin particles are washed with 200 mL of deionized water and dried in a freeze dryer for 24 hours to obtain a resin particle powder. 0.130 g of resin particle powder is weighed out and molded into a disk shape. The molded product is used as a sample for qualitative and quantitative total elemental analysis using X-ray fluorescence analysis to determine the sulfur element content (mass%). X-ray fluorescence analysis is performed using the following equipment and conditions. Scanning X-ray fluorescence analyzer: ZSX Primus II, Rigaku Corporation X-ray output: 40mA~70mA ·Measurement area: diameter 10mm Measurement time: 15 minutes When the peak of elemental sulfur overlaps with the peak of other elements, further analysis is carried out by ICP emission spectroscopy and / or atomic absorption spectroscopy to determine the content (mass %) of elemental sulfur.

[0032] In the toner manufacturing method of the present disclosure, from the viewpoint of manufacturing a toner that suppresses the occurrence of image density unevenness, the value obtained by dividing the content of sulfur element contained in the toner particles (mass ratio to the mass of the toner particles) by the content of sulfur element contained in the amorphous resin particles (1) (mass ratio of the amorphous resin particles (1) to the mass of the amorphous resin) is preferably 1 or less, more preferably 0.9 or less, and even more preferably 0.8 or less. From the viewpoint of making it easier for moisture to remain inside the toner, the above-mentioned division value is preferably 0.4 or more, more preferably 0.6 or more, and even more preferably 0.7 or more.

[0033] In the toner manufacturing method of the present disclosure, from the viewpoint of manufacturing a toner that suppresses the occurrence of image density unevenness, the toner particles contain nitrogen element, and the value (ppm / mass%) obtained by dividing the nitrogen element content (ppm) on the surface of the toner particles by the sulfur element content (mass ratio to the mass of the toner particles, mass%) contained in the toner particles is preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less. It is presumed that the presence of nitrogen element, which has a higher electronegativity than sulfur element, on the toner surface can further promote the movement of moisture from the toner surface to the inside of the toner. The above division value is preferably 3 or more, more preferably 6 or more, and even more preferably 10 or more, from the viewpoint of facilitating retention of moisture inside the toner.

[0034] In the toner manufacturing method of the present disclosure, the nitrogen element content on the surface of the toner particles is preferably 0.3 ppm to 10 ppm, more preferably 0.5 ppm to 8 ppm, and even more preferably 0.7 ppm to 5 ppm.

[0035] The nitrogen content on the surface of toner particles can be controlled by using an appropriate amount of a material containing a nitrogen element when granulating the raw particles of the toner particles and / or when granulating the toner particles. Examples of materials containing a nitrogen element include surfactants, binder resins, chain transfer agents for resins, and pH adjusters, and pH adjusters containing a nitrogen element are preferred. Examples include counter ions of anionic surfactants, nitric acid, ammonium nitrate, and ammonium sulfate.

[0036] The nitrogen element content on the surface of the toner particles is determined by the following measurement method. When the toner contains an external additive, the external additive is removed from the toner particles by ultrasonic treatment. Specifically, 1% by mass of the toner is added to a 10% by mass aqueous solution of ethanol, and ultrasonic vibrations at a power of 20 W and a frequency of 20 kHz are applied for 30 minutes to remove the external additive from the toner particles, followed by centrifugal separation and drying to obtain toner particles. 0.5 g of toner particles were precisely weighed, 1 g of a 10% by weight nonionic surfactant and 98.5 ml of ultrapure water were added, and the toner particles were dispersed in a thermostatic chamber controlled at 30°C ± 1°C for 30 minutes by applying ultrasonic waves. The toner particles were filtered from the dispersion, and the cationic and anionic components of the filtrate were quantified using ion chromatography (ICS-2000, Nippon Dionex Co., Ltd.). The nitrogen content (ppm) was quantified by integrating the amount of nitrogen in ions containing nitrogen (e.g., ammonium ions, nitrate ions) among the cationic and anionic components.

[0037] The amorphous resin particles (1) and the amorphous resin particles (2) will be described in detail below.

[0038] [Amorphous resin particles (1)] The amorphous resin particles (1) are resin particles obtained by melt-mixing an amorphous resin, adding an aqueous medium, and granulating the mixture.

[0039] Examples of a method for granulating the amorphous resin particles (1) include a method in which an amorphous resin and, if necessary, a basic compound and a surfactant are mixed by applying heat and shear force, and then an aqueous medium is added while applying shear force to granulate the mixture.

[0040] The apparatus used for granulating the amorphous resin particles (1) is not particularly limited and can be appropriately selected depending on the purpose. Examples of the apparatus include a batch kneader and a kneading extruder, with a kneading extruder being preferred. A kneading extruder is an apparatus that applies heat and shear force to a material to be treated while continuously conveying the material. The structure of a kneading extruder is generally broadly divided into a material inlet, a barrel, and a die, from upstream to downstream. A screw is provided inside the barrel. A heater is provided around the barrel to heat the inside of the barrel. The screw may be a single-screw type or a twin-screw type, with a twin-screw type being preferred.

[0041] The basic compound is preferably sodium hydroxide or potassium hydroxide. From the viewpoint of uniformity in kneading, sodium hydroxide or potassium hydroxide is preferably used in the form of an aqueous solution (i.e., an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution).

[0042] The amount of the basic compound used is an amount that allows the mixture to be dispersed in an aqueous medium, and specifically, the amount of the basic compound used is preferably an amount that results in a neutralization rate of 30% or more and 60% or less according to the following formula (1): Formula (1): Neutralization rate (%) = mb×n×56.1÷Mwb÷AV×1000, mb is the amount (g) of basic compound used per 1 g of resin, n is the valence of the basic compound, Mwb is the molecular weight of the basic compound, AV is the acid value of the resin (mg KOH / g).

[0043] The surfactant may be any of anionic surfactants, cationic surfactants, and nonionic surfactants. Examples include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. One surfactant may be used alone, or two or more surfactants may be used in combination. A nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant. The amount of surfactant used is an amount that allows the particles dispersed in the aqueous medium to remain dispersed.

[0044] As the surfactant, it is preferable to use an appropriate amount of a sulfonate surfactant from the viewpoint of controlling the content of elemental sulfur contained in the amorphous resin particles (1) to a desired value.

[0045] The aqueous medium is preferably water with a reduced ion content, such as distilled water or ion-exchanged water. The aqueous medium is preferably used by adjusting its temperature to a range of 35°C or higher and 100°C or lower, more preferably within ±5°C of the internal barrel temperature of the kneading extruder.

[0046] The temperature inside the barrel of the kneading extruder is preferably 80°C or higher and 110°C or lower, more preferably 85°C or higher and 105°C or lower, and even more preferably 90°C or higher and 100°C or lower.

[0047] The amorphous resin constituting the amorphous resin particles (1) is preferably an amorphous polyester resin. The amorphous polyester resin may be a commercially available product or a synthetic product. Examples of amorphous polyester resins include condensation polymers of polycarboxylic acids and polyhydric alcohols.

[0048] Examples of polycarboxylic acids that are polymerization components of amorphous polyester resins include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, orthophthalic acid, and naphthalenedicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. The polycarboxylic acid may be a trivalent or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (e.g., carbon number 1 to 5) alkyl esters thereof. The polycarboxylic acids may be used alone or in combination of two or more.

[0049] Examples of polyhydric alcohols that are polymerization components of amorphous polyester resins include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl 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, 1,1 Examples of the polyhydric alcohol include 1-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol, alicyclic diols (for example, cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A), and aromatic diols (for example, an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A). Among these, aliphatic diols are preferred as the polyhydric alcohol. As the polyhydric alcohol which is a polymerization component of the amorphous polyester resin, a trihydric or higher polyhydric alcohol having a crosslinked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more.

[0050] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 70°C or lower, more preferably 52°C or higher and 65°C or lower, and even more preferably 54°C or higher and 60°C or lower. The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, from the "extrapolated glass transition onset temperature" described in the method for determining glass transition temperature in JIS K7121-1987 "Method for measuring transition temperature of plastics."

[0051] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less. The number average molecular weight (Mn) of the amorphous polyester resin is preferably 1,500 or more and 100,000 or less, and more preferably 2,000 or more and 95,000 or less. The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

[0052] The weight average molecular weight and number average molecular weight are measured by gel permeation chromatography (GPC). Molecular weight measurement by GPC is performed using a measuring device HLC-8120GPC (Tosoh Corporation) and a column TSKgel SuperHM-M (diameter 15 cm, Tosoh Corporation) with a solvent of tetrahydrofuran. The weight average molecular weight and number average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0053] [Amorphous resin particles (2)] The amorphous resin particles (2) are resin particles obtained by dissolving and mixing an amorphous resin and an organic solvent, and then adding an aqueous medium to the mixture to granulate the mixture.

[0054] Examples of methods for granulating the amorphous resin particles (2) include a method in which an amorphous resin and an organic solvent in which the amorphous resin is soluble are mixed while applying heat to dissolve the amorphous resin in the organic solvent, followed by mixing with a basic compound, and then adding an aqueous medium while applying shear force to granulate the mixture.

[0055] Granulation of the amorphous resin particles (2) is preferably carried out in a stirring tank equipped with a stirring means and a heating / cooling means. The stirring means is preferably a stirring means having a rotating shaft and a stirring blade. The heating / cooling means is preferably a means for applying and / or removing heat from the wall surface of the stirring tank.

[0056] When the amorphous resin is an amorphous polyester resin, examples of organic solvents that can dissolve the amorphous polyester resin include ethyl acetate, isopropanol, 2-butanol, methyl ethyl ketone, and mixed solvents thereof. Among these, organic solvents or mixed solvents having a boiling point of 60°C or higher and lower than 100°C are preferred.

[0057] Ammonia water is suitable as the basic compound.

[0058] The amount of the basic compound used is an amount that allows the mixture to be dispersed in an aqueous medium, and specifically, the amount of the basic compound used is preferably an amount that results in a neutralization rate of 50% or more and 100% or less according to the following formula (1): Formula (1): Neutralization rate (%) = mb×n×56.1÷Mwb÷AV×1000, mb is the amount (g) of basic compound used per 1 g of resin, n is the valence of the basic compound, Mwb is the molecular weight of the basic compound, AV is the acid value of the resin (mg KOH / g).

[0059] The aqueous medium is preferably water with a reduced ion content, such as distilled water or ion-exchanged water. The aqueous medium is preferably used at a temperature adjusted to a range of 35°C or higher and 100°C or lower (preferably a range of 35°C or higher and 55°C or lower).

[0060] The temperature of the material to be treated contained in the stirring tank is preferably 25°C or higher and 60°C or lower, more preferably 30°C or higher and 55°C or lower, and even more preferably 35°C or higher and 50°C or lower.

[0061] The aqueous medium is preferably added dropwise. The time for adding a specified amount of aqueous medium (twice the amount of resin) is preferably from 10 to 150 minutes, more preferably from 20 to 140 minutes, and even more preferably from 30 to 130 minutes.

[0062] After the addition of the aqueous medium is completed, it is preferable to remove the organic solvent by reducing the pressure inside the stirring tank and / or bubbling the dispersion. Thereafter, a surfactant may be added to improve the dispersion stability of the particles. When a surfactant is added, the amount added is an amount that allows the particles dispersed in the aqueous medium to maintain their dispersion. From the viewpoint of suppressing the content of elemental sulfur contained in the amorphous resin particles (2), it is preferable not to use a sulfonate surfactant.

[0063] The amorphous resin constituting the amorphous resin particles (2) is preferably an amorphous polyester resin. The specific and preferred forms of the amorphous polyester resin constituting the amorphous resin particles (2) are the same as the specific and preferred forms of the amorphous polyester resin constituting the amorphous resin particles (1) described above.

[0064] Each step and material of the EA method will be explained in detail below.

[0065] [First flocculation step] The first aggregation step is a step of forming cores of a toner having a core-shell structure, in which at least amorphous resin particles (1) are aggregated in a dispersion containing at least amorphous resin particles (1) to form first aggregated particles.

[0066] The dispersion liquid to be subjected to the first aggregation step contains at least amorphous resin particles (1). The dispersion liquid to be subjected to the first aggregation step may further contain crystalline resin particles. The dispersion liquid to be subjected to the first aggregation step may further contain release agent particles. The dispersion liquid to be subjected to the first aggregation step may further contain colorant particles.

[0067] The dispersion liquid to be subjected to the first aggregation step is prepared, for example, by preparing a dispersion liquid of amorphous resin particles (1), a dispersion liquid of crystalline resin particles, a dispersion liquid of release agent particles, and a dispersion liquid of colorant particles, and then mixing these particle dispersion liquids. The order in which these particle dispersion liquids are mixed is not limited.

[0068] The crystalline resin particles contained in the crystalline resin particle dispersion are preferably crystalline resin particles obtained by dissolving and mixing a crystalline resin and an organic solvent, adding an aqueous medium, and granulating the mixture. That is, the crystalline resin particle dispersion is preferably a crystalline resin particle dispersion produced by dissolving and mixing an organic solvent and adding an aqueous medium.

[0069] The specific and preferred forms of granulation of the crystalline resin particles are the same as the specific and preferred forms of granulation of the amorphous resin particles (2) described above.

[0070] When the crystalline resin is a crystalline polyester resin, examples of organic solvents that can dissolve the crystalline polyester resin include ethyl acetate, isopropanol, 2-butanol, methyl ethyl ketone, and mixed solvents thereof. Among these, organic solvents or mixed solvents having a boiling point of 60°C or higher and lower than 100°C are preferred.

[0071] -Crystalline polyester resin- The crystalline polyester resin may be a commercially available product or a synthetic product. Examples of the crystalline polyester resin include a polycondensation product of a polycarboxylic acid and a polyhydric alcohol. The crystalline polyester resin is preferably a polycondensation product using a linear aliphatic polymerizable monomer rather than a polymerizable monomer having an aromatic ring, since it easily forms a crystalline structure.

[0072] Examples of polycarboxylic acids that are polymerization components of crystalline polyester resins include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid), anhydrides thereof, and lower (e.g., having 1 to 5 carbon atoms) alkyl esters thereof. The polycarboxylic acid may be a tricarboxylic or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the tricarboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids. The polycarboxylic acids may be used alone or in combination of two or more.

[0073] Examples of polyhydric alcohols that are polymerization components of crystalline polyester resins include aliphatic diols (for example, straight-chain aliphatic diols having 7 to 20 carbon atoms in the main chain). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol. As the polyhydric alcohol, which is a polymerization component of the crystalline polyester resin, a trihydric or higher alcohol having a crosslinked or branched structure may be used in combination with the diol. Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more.

[0074] The melting temperature of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 90°C or lower, and even more preferably 60°C or higher and 85°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121-1987 "Method for measuring transition temperatures of plastics."

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

[0076] Next, the release agent particle dispersion liquid and the release agent, and the colorant particle dispersion liquid and the colorant will be described. In the following description, the release agent particle dispersion liquid and the colorant particle dispersion liquid will be collectively referred to as "particle dispersion liquid" when describing what is common to both the release agent particle dispersion liquid and the colorant particle dispersion liquid.

[0077] An example of an embodiment of the particle dispersion is a dispersion in which a material is dispersed in the form of particles in a dispersion medium by a surfactant.

[0078] The dispersion medium for the particle dispersion is preferably an aqueous medium. Examples of aqueous media include water and alcohol. The water is preferably water with a reduced ion content, such as distilled water or ion-exchanged water. These aqueous media may be used alone or in combination of two or more.

[0079] The surfactant used to disperse the material in the dispersion medium may be any of anionic surfactants, cationic surfactants, and nonionic surfactants. Examples include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soap-based surfactants; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. One surfactant may be used alone, or two or more surfactants may be used in combination. A nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant.

[0080] Methods for dispersing a material in a particulate form in a dispersion medium include known dispersion methods such as a rotary shear homogenizer, a ball mill having media, a sand mill, and a dyno mill.

[0081] The volume average particle size of the particles dispersed in the particle dispersion is preferably 30 nm or more and 300 nm or less, more preferably 50 nm or more and 250 nm or less, and even more preferably 80 nm or more and 200 nm or less. The volume average particle size of particles in a particle dispersion refers to the particle size that is the cumulative 50% particle size from the smallest diameter side in the particle size distribution measured using a laser diffraction particle size analyzer. The number of particles measured was 10,000.

[0082] The content of particles contained in the particle dispersion is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 40% by mass, and even more preferably 15% by mass to 30% by mass.

[0083] -Mold release agent- Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but are not limited thereto.

[0084] The melting temperature of the release agent is preferably 50°C or higher and 110°C or lower, and more preferably 60°C or higher and 100°C or lower. The melting temperature of the release agent is determined from a DSC curve obtained by differential scanning calorimetry (DSC) in accordance with the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121:1987 "Method for measuring transition temperatures of plastics."

[0085] -Coloring agent- Examples of colorants include carbon black, chrome yellow, Hansa Yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Balkan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, and ultramarine blue. pigments such as phthalocyanine blue, chalco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate; dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, aniline black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based; and inorganic pigments such as titanium compounds and silica. The colorant may be used alone or in combination of two or more kinds.

[0086] The colorant is not limited to a substance that absorbs light in the visible light region, but may be, for example, a substance that absorbs light in the near-infrared region, or may be a fluorescent colorant. Examples of colorants that have absorption in the near-infrared region include aminium salt compounds, naphthalocyanine compounds, squarylium compounds, and croconium compounds. Examples of fluorescent colorants include the fluorescent colorants described in paragraph 0027 of JP 2021-127431 A.

[0087] The colorant may be a colorant having luster. Examples of the luster colorant include metal powders such as aluminum, brass, bronze, nickel, stainless steel, and zinc; mica coated with titanium oxide or yellow iron oxide; coated flaky inorganic crystal substrates such as barium sulfate, layered silicates, and layered aluminum silicates; single-crystal plate-like titanium oxide, basic carbonates, bismuth oxychloride, natural guanine, flaky glass powder, and metal-deposited flaky glass powder.

[0088] The colorant may be used alone or in combination of two or more kinds. The colorant may be surface-treated as needed, and may be used in combination with a dispersant.

[0089] The toner particles may contain a colorant or may not contain a colorant. The toner may be a toner that does not contain a colorant in the toner particles, that is, a so-called transparent toner.

[0090] Hereinafter, a dispersion obtained by mixing a plurality of types of material dispersions will be referred to as a "mixed dispersion."

[0091] The mass ratio of the particles contained in the mixed dispersion is preferably in the following range. When the mixed dispersion contains release agent particles, the mass ratio of the binder resin particles to the release agent particles (binder resin particles:release agent particles) is preferably 100:1 to 100:40, more preferably 100:2 to 100:30, and even more preferably 100:5 to 100:20. When the mixed dispersion contains colorant particles, the mass ratio of the binder resin particles to the colorant particles (binder resin particles:colorant particles) is preferably 100:1 to 100:100, more preferably 100:2 to 100:40, and even more preferably 100:5 to 100:20.

[0092] After mixing the multiple material dispersions, it is preferable to adjust the pH of the mixed dispersion to a range of 3 to 4. Examples of a means for adjusting the pH of the mixed dispersion include adding an acidic aqueous solution such as a nitric acid aqueous solution, a hydrochloric acid aqueous solution, or a sulfuric acid aqueous solution.

[0093] The aggregation step may be carried out, for example, by adding a flocculant to the mixed dispersion while stirring the mixed dispersion; After adding the aggregating agent to the mixed dispersion, the mixed dispersion is heated while being stirred to increase the temperature of the mixed dispersion.

[0094] Examples of the flocculant include a surfactant having an opposite polarity to the surfactant contained in the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. One type of flocculant may be used alone, or two or more types may be used in combination.

[0095] 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; and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.

[0096] The flocculant is preferably a divalent or higher metal salt compound, more preferably a trivalent metal salt compound, and even more preferably a trivalent inorganic aluminum salt compound, such as aluminum chloride, aluminum sulfate, polyaluminum chloride, or polyaluminum hydroxide.

[0097] The amount of the flocculant to be added is not limited. When a trivalent metal salt compound is used as the flocculant, the amount of the trivalent metal salt compound to be added is preferably 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.05 parts by mass or more and 5 parts by mass or less, and even more preferably 0.1 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0098] The temperature that the mixed dispersion reaches when heated is preferably a temperature based on the glass transition temperature (Tg) of the binder resin particles, for example, (Tg-30°C) or higher and (Tg°C) or lower of the binder resin particles. When the mixed dispersion contains a plurality of types of binder resin particles having different Tg's, the lowest temperature among the Tg's is set as the Tg in the aggregation step.

[0099] [Second flocculation step] The second aggregation step is a step of forming second aggregated particles by adhering amorphous resin particles (2) to the surfaces of the first aggregated particles, i.e., the second aggregation step is a step of forming the shell of the toner having a core-shell structure.

[0100] The second aggregation step may be, for example, adding a dispersion containing amorphous resin particles (2) to form shells to the dispersion containing the first aggregated particles while stirring the dispersion, and mixing the two dispersions; and heating the mixed dispersion while stirring.

[0101] The temperature to which the mixed dispersion liquid is heated is preferably a temperature based on the glass transition temperature (Tg) of the amorphous resin particles (2) that form the shell, for example, a temperature not lower than (Tg-30°C) and not higher than (Tg-10°C) of the amorphous resin particles (2).

[0102] After the second aggregated particles have grown to a predetermined size, a chelating agent for the aggregating agent used in the aggregation step may be added to the dispersion containing the second aggregated particles in order to stop the growth of the second aggregated particles before the heating step of the coalescence step. Examples of chelating agents include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; and aminocarboxylic acids such as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). The amount of the chelating agent added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, relative to 100 parts by mass of the binder resin particles.

[0103] After the second aggregated particles have grown to a predetermined size, the pH of the dispersion containing the second aggregated particles may be increased to stop the growth of the second aggregated particles before the heating step of the coalescence step is performed. The pH of the dispersion containing the second aggregated particles is preferably 8 or more and 10 or less. The pH of the dispersion containing the second aggregated particles can be increased by adding at least one solution selected from the group consisting of an aqueous solution of an alkali metal hydroxide and an aqueous solution of an alkaline earth metal hydroxide.

[0104] [Uniting process] The coalescence step is a step in which the dispersion liquid containing the second aggregated particles is heated to fuse and coalesce the aggregated particles to form toner particles.

[0105] The temperature reached by the dispersion containing the second aggregated particles is preferably equal to or higher than the glass transition temperature (Tg) of the binder resin, and specifically, is preferably 10° C. to 30° C. higher than the Tg of the binder resin. When the aggregated particles contain a plurality of binder resins having different Tg's, the highest temperature among the Tg's is taken as the glass transition temperature in the coalescence step.

[0106] After the coalescence step, the toner particles in the dispersion are subjected to a known washing step, solid-liquid separation step, and drying step to obtain dried toner particles. In the washing step, from the viewpoint of chargeability, it is preferable to perform sufficient substitution washing with ion-exchanged water. In the solid-liquid separation step, it is preferable to perform suction filtration, pressure filtration, etc., from the viewpoint of productivity. In the drying step, it is preferable to perform freeze drying, flash drying, fluidized drying, vibration-type fluidized drying, etc., from the viewpoint of productivity.

[0107] [Step of adding external additives] The method for producing the toner of the present disclosure preferably includes a step of externally adding an external additive to the toner particles. The external additive is added to the toner particles by mixing the dry toner particles with the external additive. The mixing can be performed using, for example, a V blender, a Henschel mixer, a Loedige mixer, etc. Furthermore, if necessary, coarse particles of the toner can be removed using a vibrating sieve, an air sieve, etc.

[0108] Examples of external additives include inorganic particles, such as SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, and K2O·(TiO2). n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, SrTiO3, etc.

[0109] The surfaces of inorganic particles as external additives are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is usually, for example, 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the inorganic particles.

[0110] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate, and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based polymers).

[0111] The amount of the external additive added is preferably 0.01% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass, based on the mass of the toner particles.

[0112] <Toner for developing electrostatic images> The toner of the present disclosure is produced by the toner production method of the present disclosure. The toner of the present disclosure contains at least toner particles. The toner according to this embodiment preferably contains toner particles and an external additive. The form of the external additive is as described above.

[0113] The toner particles constituting the toner of the present disclosure are toner particles with a core-shell structure having a core containing an amorphous resin (1) and a shell that coats the core and contains an amorphous resin (2). The amorphous resin (1) has the same meaning as the amorphous resin constituting the amorphous resin particles (1), and the preferred form is also the same. The amorphous resin (2) has the same meaning as the amorphous resin constituting the amorphous resin particles (2), and the preferred form is also the same.

[0114] The toner particles have a core-shell structure having a core containing at least an amorphous resin (1) and a shell containing at least an amorphous resin (2). The toner particles may contain a crystalline resin in the core. The toner particles may contain a release agent in the core. The toner particles may contain a colorant in the core. The toner particles may contain a crystalline resin, a release agent, and a colorant in the shell. The shell may have a multi-layer structure. The type of resin, physical properties such as glass transition temperature (Tg) and SP value, and the presence and type of colorant and release agent may be different for each core and shell layer.

[0115] The amorphous resin (1) is preferably an amorphous polyester resin, and the amorphous resin (2) is preferably an amorphous polyester resin. The total content of the amorphous polyester resin is preferably 40% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and even more preferably 60% by mass to 85% by mass, based on the total amount of the toner particles.

[0116] When the toner particles contain a crystalline resin, the crystalline resin is preferably a crystalline polyester resin. The content of the crystalline polyester resin is preferably 3% by mass or more and 30% by mass or less, and more preferably 8% by mass or more and 20% by mass or less, of the total binder resin of the toner particles.

[0117] When the toner particles contain a release agent, the content of the release agent is preferably from 1% by mass to 20% by mass, and more preferably from 5% by mass to 15% by mass, based on the total mass of the toner particles.

[0118] When the toner particles contain a colorant, the content of the colorant is preferably from 1% by mass to 30% by mass, and more preferably from 3% by mass to 15% by mass, based on the total mass of the toner particles.

[0119] The volume average particle size 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. The volume average particle size of the toner is measured by the following method. The particle size distribution of the toner was measured using a Coulter Multisizer 4e (manufactured by Beckman Coulter) and an ISOTON-II (manufactured by Beckman Coulter) electrolyte. For the measurement, 0.5 mg to 50 mg of the sample to be measured was added to 2 ml of a 5% by weight aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant. This was then added to 100 ml to 150 ml of electrolyte. The electrolyte containing the suspended sample was dispersed in an ultrasonic disperser for 1 minute, and the particle size distribution of particles ranging from 2 μm to 60 μm was measured using a Coulter Multisizer 4e with an aperture diameter of 100 μm. 50,000 particles were sampled. The particle size distribution was plotted from the smallest diameter end, and the particle size at 50% of the cumulative size was taken as the volume average particle size D50v.

[0120] The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less. The average circularity of toner particles is calculated by dividing the perimeter of a circle having the same area as the projected image of a particle by the perimeter of the projected image of the particle. This is determined by sampling 3,500 particles using a flow particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation).

[0121] <Electrostatic image developer> The electrostatic image developer according to the present embodiment contains at least the toner according to the present embodiment. The electrostatic image developer according to the present embodiment may be a one-component developer containing only the toner, or may be a two-component developer in which the toner and a carrier are mixed.

[0122] The carrier is not particularly limited, and examples thereof include known carriers, such as coated carriers in which the surface of a core material made of magnetic powder is coated with a coating resin, magnetic powder dispersion carriers in which magnetic powder is dispersed and blended in a matrix resin, and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin. The magnetic powder dispersion type carrier and the resin impregnated type carrier may be a carrier in which the constituent particles of the carrier are used as a core material and are coated with a coating resin.

[0123] Examples of magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0124] Examples of coating resins and matrix resins include styrene-(meth)acrylic acid resins; polyolefin resins such as polyethylene resins and polypropylene resins; polyvinyl or polyvinylidene resins such as polystyrene, (meth)acrylic resins, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymers; straight silicone resins or modified silicone resins consisting of organosiloxane bonds; fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; and epoxy resins.

[0125] The coating resin and the matrix resin preferably contain a (meth)acrylic resin, more preferably contain 50% by mass or more, and even more preferably contain 80% by mass or more of a (meth)acrylic resin relative to the total mass of the resin. The coating resin and the matrix resin preferably contain an alicyclic (meth)acrylic resin as the (meth)acrylic resin.

[0126] The coating resin and the matrix resin may contain other additives such as conductive particles. Examples of conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0127] Examples of methods for forming a coating resin on the surface of a core material include a method of coating with a solution for forming a coating layer in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be selected taking into consideration the coating resin to be used, its applicability, etc. Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer, a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material, a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air, and a kneader coater method in which the core material of the carrier and the solution for forming a coating layer are mixed in a kneader coater and the solvent is removed.

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

[0129] <Image forming apparatus and image forming method> The image forming apparatus according to the present embodiment includes an image carrier, a charging device that charges the surface of the image carrier, an electrostatic image forming device that forms an electrostatic image on the surface of the charged image carrier, a developing device that contains an electrostatic image developer and develops the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer, a transfer device that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing device that fixes the toner image transferred to the surface of the recording medium. The electrostatic image developer according to the present embodiment is used as the electrostatic image developer.

[0130] The image forming apparatus according to this embodiment carries out an image forming method (the image forming method according to this embodiment) that includes a charging step of charging the surface of an image carrier, an electrostatic image forming step of forming an electrostatic image on the surface of the charged image carrier, a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to this embodiment, a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0131] The image forming apparatus according to the present embodiment may be a known image forming apparatus such as a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image carrier to a recording medium; an intermediate transfer type apparatus that primarily transfers a toner image formed on the surface of an image carrier to the surface of an intermediate transfer medium, and then secondarily transfers the toner image transferred to the surface of the intermediate transfer medium to the surface of a recording medium; an apparatus equipped with a cleaning device that cleans the surface of the image carrier after the transfer of the toner image but before charging; or an apparatus equipped with a static elimination device that irradiates the surface of the image carrier with static elimination light to eliminate static after the transfer of the toner image but before charging. In the case of an intermediate transfer type device, the transfer device is configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer device that performs primary transfer of the toner image formed on the surface of the image carrier onto the surface of the intermediate transfer body, and a secondary transfer device that performs secondary transfer of the toner image transferred onto the surface of the intermediate transfer body onto the surface of the recording medium.

[0132] In the image forming apparatus according to the present embodiment, for example, a portion including the developing device may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with a developing device that accommodates the electrostatic image developer according to the present embodiment is preferably used.

[0133] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. The main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0134] FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to this embodiment. The image forming apparatus shown in Figure 1 includes first through fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K that output images in the colors yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side horizontally spaced a predetermined distance apart from one another. Each of units 10Y, 10M, 10C, and 10K may be a process cartridge that is detachably attached to the image forming apparatus.

[0135] Above each of the units 10Y, 10M, 10C, and 10K in the drawing, an intermediate transfer belt 20 serving as an intermediate transfer body extends through each unit. The intermediate transfer belt 20 is wound around a drive roll 22 and a support roll 24 that contact the inner surface of the intermediate transfer belt 20, which are arranged spaced apart from each other from left to right in the drawing, and runs in a direction from the first unit 10Y to the fourth unit 10K. A force is applied to the support roll 24 by a spring or the like (not shown) in a direction away from the drive roll 22, thereby applying tension to the intermediate transfer belt 20 wound around them. An intermediate transfer body cleaning device 30 is provided on the outer circumferential surface of the intermediate transfer belt 20, facing the drive roll 22. The developing devices (examples of developing devices) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K are supplied with toner, including four colors of toner: yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K.

[0136] Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, the first unit 10Y, which forms a yellow image and is disposed upstream in the direction of travel of the intermediate transfer belt, will be described here as a representative. By assigning magenta (M), cyan (C), and black (K) reference numerals instead of yellow (Y) to parts equivalent to those of the first unit 10Y, descriptions of the second to fourth units 10M, 10C, and 10K will be omitted.

[0137] The first unit 10Y has a photoreceptor 1Y that acts as an image carrier. Around the photoreceptor 1Y, there are arranged in this order: a charging roll (an example of a charging 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 to a laser beam 3Y based on a color-separated image signal to form an electrostatic image; a developing device (an example of a developing device) 4Y that supplies charged toner to the electrostatic image to develop it; a primary transfer roll (an example of a primary transfer device) 5Y that transfers the developed toner image onto the intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning device) 6Y that removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer. The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20 and is provided at a position facing the photoreceptor 1Y. A bias power supply (not shown) that applies a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power supply varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

[0138] The operation of forming a yellow image in first unit 10Y will be described below. Prior to operation, the surface of the photoreceptor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y. The photoconductor 1Y has conductivity (for example, volume resistivity at 20°C: 1×10 -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate with a resistivity of Ωcm or less. This photosensitive layer normally has a high resistance (the resistance of ordinary resins), but when irradiated with a laser beam 3Y, the resistivity of the irradiated portion changes. Therefore, a laser beam 3Y is output to the charged surface of the photosensitive element 1Y via an exposure device 3 in accordance with image data for yellow sent from a control unit (not shown). The laser beam 3Y is irradiated onto the photosensitive layer on the surface of the photosensitive element 1Y, thereby forming an electrostatic charge image of a yellow image pattern on the surface of the photosensitive element 1Y.

[0139] An electrostatic image is an image formed on the surface of the photosensitive element 1Y by charging it; it is a so-called negative latent image formed when the resistivity of the irradiated portion of the photosensitive layer is reduced by the laser beam 3Y, causing the charged charges on the surface of the photosensitive element 1Y to flow, and the charges remaining in the portions not irradiated by the laser beam 3Y. The electrostatic image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y travels, and at this development position, the electrostatic image on the photoreceptor 1Y is visualized (developed) as a toner image by the developing device 4Y.

[0140] The developing device 4Y contains an electrostatic image developer containing, for example, at least yellow toner and a carrier. The yellow toner is frictionally charged by being stirred inside the developing device 4Y, and is held on a developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. The photoreceptor 1Y on which the yellow toner image has been formed continues to travel at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0141] 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 to the primary transfer roll 5Y acts on the toner image, causing the toner image on the photoreceptor 1Y to be transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the (-) polarity of the toner, and in the first unit 10Y, for example, it is controlled to +10 μA by a control unit (not shown). The toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

[0142] The primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K of the second unit 10M and subsequent units is also controlled in accordance with the first unit. In this way, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is conveyed sequentially through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are transferred onto the intermediate transfer belt 20 in a superimposed manner.

[0143] The intermediate transfer belt 20, onto which the four-color toner images have been multiplex-transferred through the first to fourth units, reaches a secondary transfer section consisting of the intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer device) 26 located on the outer circumferential surface of the intermediate transfer belt 20. Recording paper (an example of a recording medium) P is fed via a supply mechanism into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 at a predetermined timing, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has a negative polarity, the same as the negative polarity of the toner. Electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. The secondary transfer bias at this time is determined based on the resistance detected by a resistance detection device (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0144] Thereafter, the recording paper P is sent to the pressure contact portion (nip portion) of a pair of fixing rolls in a fixing device (an example of a fixing device) 28, where the toner image is fixed onto the recording paper P, forming a fixed image.

[0145] Examples of the recording paper P onto which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, etc. In addition to the recording paper P, examples of the recording medium include overhead projector sheets and the like. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper in which the surface of plain paper is coated with resin or the like, or art paper for printing, is preferably used.

[0146] The recording paper P on which the color image has been fixed is conveyed toward the discharge section, and the series of color image forming operations is completed.

[0147] <Process cartridges and toner cartridges> The process cartridge according to this embodiment is a process cartridge that is detachably attached to an image forming apparatus and that contains the electrostatic image developer according to this embodiment and is equipped with a developing device that develops an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image.

[0148] The process cartridge according to this embodiment is not limited to the above configuration, and may be configured to include a developing device and, if necessary, at least one other device selected from, for example, an image carrier, a charging device, an electrostatic image forming device, a transfer device, etc.

[0149] An example of a process cartridge according to this embodiment will be described below, but the present invention is not limited to this. The main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0150] FIG. 2 is a schematic diagram showing the configuration of the process cartridge according to the present embodiment. The process cartridge 200 shown in FIG. 2 is configured to integrally combine and hold a photosensitive member 107 (an example of an image carrier), a charging roll 108 (an example of a charging device) provided around the photosensitive member 107, a developing device 111 (an example of a developing device), and a photosensitive member cleaning device 113 (an example of a cleaning device), all of which are held by a housing 117 provided with, for example, mounting rails 116 and an opening 118 for exposure, and is formed into a cartridge. In FIG. 2, 109 denotes an exposure device (an example of an electrostatic image forming device), 112 denotes a transfer device (an example of a transfer device), 115 denotes a fixing device (an example of a fixing device), and 300 denotes recording paper (an example of a recording medium).

[0151] The toner cartridge according to the present embodiment is a toner cartridge that contains the toner according to the present embodiment and is detachably attached to an image forming apparatus. The toner cartridge contains replenishment toner to be supplied to a developing device provided in the image forming apparatus.

[0152] 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to each developing device (color) by toner supply pipes (not shown). When the toner contained in a toner cartridge runs low, the toner cartridge is replaced. [Example]

[0153] Hereinafter, the embodiments will be described in detail with reference to examples, but the embodiments are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are by mass. In the following description, unless otherwise specified, synthesis, production, treatment, measurement, etc. were carried out at room temperature (25°C ± 3°C).

[0154] <Preparation of amorphous polyester resin (a)> Terephthalic acid: 90 parts Fumaric acid: 10 parts Bisphenol A propylene oxide 2 mole adduct: 95 parts Neopentyl glycol: 5 parts The above materials were placed in a flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and distillation column, and the temperature was raised to 210°C over 1 hour. Then, 1 part of titanium tetraethoxide was added for every 100 parts of the above materials. The temperature was raised to 230°C over 0.5 hours while distilling off the resulting water. The dehydration condensation reaction was continued at that temperature for 1 hour, and then the reaction mixture was cooled. Thus, an amorphous polyester resin (a) was obtained with a weight-average molecular weight (Mw) of 18,000, a glass transition temperature of 60°C, and an acid value of 12.0 mgKOH / g.

[0155] <Preparation of Crystalline Polyester Resin (b)> Sebacic acid: 279 parts 1,6-Hexanediol: 163 parts Dibutyltin oxide (catalyst): 0.7 parts The above materials were placed in a heated and dried three-necked flask, the air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed with mechanical stirring at 180°C for 6 hours, yielding a crystalline polyester resin (b) with a weight-average molecular weight (Mw) of 29,000 and an acid value of 8.8 mgKOH / g.

[0156] <Preparation of Amorphous Polyester Resin Particle Dispersion (1)> [Amorphous polyester resin particle dispersion (1-1)] The following materials were prepared: Amorphous polyester resin (a) (weight average molecular weight 18,000, glass transition temperature 60°C, acid value 12.0 mgKOH / g): 500 parts Basic compound: 25% aqueous solution of sodium hydroxide: 7.7 parts Surfactant: 48.5% sodium dodecyldiphenyletherdisulfonate aqueous solution (trade name: Eleminol MON-7, Sanyo Chemical Industries, Ltd.): 17.0 parts Ion-exchanged water (1): 125 parts of ion-exchanged water at 85°C Ion-exchanged water (2): 125 parts of ion-exchanged water at 85°C Ion-exchanged water (3): 125 parts of ion-exchanged water at 85°C

[0157] A twin-screw kneading extruder (model number: TEM26SS, Toshiba Machine Co., Ltd.) was prepared. The barrel of the twin-screw kneading extruder used in this example was formed by connecting a plurality of barrel blocks.

[0158] -Melting process- The barrel temperature of the twin-screw kneading extruder was set to 85°C, and the screw rotation speed was set to 400 rpm. The amorphous polyester resin and basic compound were fed into the raw material inlet of the twin-screw kneading extruder, and the twin-screw kneading extruder was started. The surfactant was fed from the fourth barrel block, and the mixture was kneaded and mixed to melt the resin, producing a mixture.

[0159] -Dispersion process- While operating the twin-screw kneading extruder so that the average feed rate of the mixture was 12 kg / h, ion-exchanged water (1) was added from the barrel of the fifth block, ion-exchanged water (2) was added from the barrel of the seventh block, and ion-exchanged water (3) was added from the barrel of the ninth block, and the mixture was dispersed in an aqueous medium to obtain an amorphous polyester resin particle dispersion (1-1). The solids concentration of the amorphous polyester resin particle dispersion (1-1) was 30%.

[0160] The particle size distribution of the particles in the resin particle dispersion was measured using a laser diffraction particle size distribution analyzer (model number: LS13-320, Beckman Coulter, Inc.). The volume average particle size D50v, which is the cumulative 50% from the smallest diameter side in the volume-based particle size distribution, was calculated. D16v, which is the cumulative 16% from the smallest diameter side, and D84v, which is the cumulative 84% from the smallest diameter side, were calculated, and the particle size distribution index GSDv was calculated using the following formula (2). The measurement results are shown in Table 1. Formula (2): GSDv=(D84v / D16v) 1 / 2

[0161] The sulfur element content (mass ratio relative to the mass of the amorphous polyester resin) contained in the amorphous polyester resin particles (1-1) was determined by the aforementioned measurement method using fluorescent X-ray analysis. The sulfur element content is shown in Table 1.

[0162] [Amorphous polyester resin particle dispersions (1-2) to (1-4)] Amorphous polyester resin particle dispersions of each example were prepared in the same manner as in the production of amorphous polyester resin particle dispersion (1-1), except that the amounts of materials used were changed as shown in Table 1.

[0163] [Table 1]

[0164] <Preparation of Amorphous Polyester Resin Particle Dispersion (2)> [Amorphous polyester resin particle dispersion (2-1)] The following materials were prepared: Organic solvent (1): Ethyl acetate: 60 parts Organic solvent (2): Isopropanol: 24 parts Amorphous polyester resin (a) (weight average molecular weight 18,000, glass transition temperature 60°C, acid value 12.0 mgKOH / g): 100 parts Basic compound: 10% ammonia water: 3.3 parts Ion-exchanged water (4): 500 parts of ion-exchanged water at 40°C

[0165] -Process (1)- Organic solvent (1) and organic solvent (2) were charged into a stirring vessel equipped with a stirrer, a condenser, a heater, and a thermometer to prepare a mixed solvent. The temperature inside the stirring vessel was kept at 50°C and the amorphous polyester resin was charged while stirring, and the mixture was stirred for 30 minutes to dissolve the resin in the organic solvent.

[0166] -Dispersion process- While maintaining the temperature inside the stirring tank and continuing stirring, 10% ammonia water was added, and then ion-exchanged water (4) was added dropwise to disperse the contents into the aqueous medium. Heating of the stirring tank was stopped, and the temperature of the dispersion was lowered to room temperature, and then the pressure inside the stirring tank was reduced to remove the organic solvent from the dispersion. The dispersion was passed through a sieve to obtain amorphous polyester resin particle dispersion (2-1). The solids concentration of amorphous polyester resin particle dispersion (2-1) was 30%.

[0167] The particle size distribution of the particles in the amorphous polyester resin particle dispersion (2-1) was measured using a laser diffraction particle size distribution analyzer (model number: LS13-320, Beckman Coulter, Inc.). The volume average particle size D50v and particle size distribution index GSDv are shown in Table 2.

[0168] The sulfur element content (mass ratio relative to the mass of the amorphous polyester resin) contained in the amorphous polyester resin particles (2-1) was determined by the aforementioned measurement method using fluorescent X-ray analysis. The sulfur element content is shown in Table 2.

[0169] [Amorphous polyester resin particle dispersion (2-2)] 0.8 parts of a surfactant 48.5% sodium dodecyldiphenyletherdisulfonate aqueous solution (trade name: Eleminol MON-7, Sanyo Chemical Industries, Ltd.) was added to the amorphous polyester resin particle dispersion liquid (2-1), and the mixture was kept at 60°C for 1 hour to prepare the amorphous polyester resin particle dispersion liquid (2-2) shown in Table 2.

[0170] [Table 2]

[0171] <Preparation of Crystalline Polyester Resin Particle Dispersion (1)> Crystalline polyester resin (b) (weight average molecular weight 29,000, acid value 8.8 mg KOH / g): 100 parts Methyl ethyl ketone: 70 parts Isopropanol: 12 parts 10% aqueous ammonia solution: 3 parts The above materials were placed in a jacketed reactor equipped with a condenser, thermometer, water dripper, and anchor blade. The liquid temperature was maintained at 80°C in a water-circulating thermostatic bath while stirring and mixing at 100 rpm to dissolve the crystalline polyester resin. The water-circulating thermostatic bath was then set to 60°C, and a total of 300 parts of ion-exchanged water maintained at 60°C was added dropwise at a rate of 3 parts / min to induce phase inversion, resulting in a dispersion. The dispersion was placed in an eggplant flask and attached to an evaporator equipped with a vacuum control unit via a trap bulb. The eggplant flask was heated in a hot water bath at 60°C while rotating. The pressure was reduced to 7 kPa while taking care to prevent bumping, and the solvent was removed. The pressure was then returned to normal, and the eggplant flask was water-cooled to obtain a dispersion. Ion-exchanged water was added to the dispersion to obtain a crystalline polyester resin particle dispersion (1) with a solids content of 20% by mass. The volume average particle size of the crystalline polyester resin particles was 160 nm.

[0172] <Preparation of Release Agent Particle Dispersion (1)> Paraffin wax (HNP-9, Nippon Seiro Co., Ltd.): 20 parts Ion-exchanged water: 80 parts Anionic surfactant (20% aqueous solution of dodecylbenzenesulfonic acid, Neogen RK, Daiichi Kogyo Seiyaku Co., Ltd.): 1 part The above materials were mixed and heated to 100°C, and dispersed using a homogenizer (Ultra Turrax T50, IKA), followed by a pressure discharge homogenizer (Manton-Gaulin high-pressure homogenizer, Gaulin). The particles were collected when the volume average particle size reached 200 nm. An appropriate amount of ion-exchanged water was added to obtain a release agent particle dispersion (1) with a solids concentration of 20%.

[0173] <Preparation of Colorant Particle Dispersion (1)> Cyan pigment (CI Pigment Blue 15:3, Dainichiseika Color & Chemicals Mfg. Co., Ltd.): 20 parts Ion-exchanged water: 80 parts Anionic surfactant (20% aqueous solution of dodecylbenzenesulfonic acid, Neogen RK, Daiichi Kogyo Seiyaku Co., Ltd.): 1 part The above materials were mixed and dispersed for 1 hour using a high-pressure impact disperser (Ultimizer HJP30006, manufactured by Sugino Machine Co., Ltd.), and the mixture was collected when the volume average particle size reached 180 nm. An appropriate amount of ion-exchanged water was added to obtain a colorant particle dispersion (1) with a solids concentration of 20%.

[0174] Example 1: Production of toner and developer [Toner particle production] -First coagulation process- Ion-exchanged water: 50 parts Amorphous polyester resin particle dispersion (1-1): 30 parts Crystalline polyester resin particle dispersion (1): 13 parts Release agent particle dispersion (1): 10 parts Colorant particle dispersion (1): 11 parts Anionic surfactant (20% aqueous solution of dodecylbenzenesulfonic acid, Neogen RK, Daiichi Kogyo Seiyaku Co., Ltd.): 1 part 1% ammonium sulfate solution: 1.8 parts The above materials were placed in a round stainless steel flask, and 0.1 N nitric acid was added to adjust the pH to 3.5. 30 parts of a nitric acid aqueous solution containing 10% polyaluminum chloride was then added. The liquid temperature was adjusted to 30°C using an oil bath, and the mixture was dispersed using a homogenizer (Ultra-Turrax T50, IKA). The liquid temperature was then raised to 45°C and maintained for 160 minutes to form primary aggregate particles.

[0175] -Second coagulation process- While maintaining the temperature of the dispersion containing the first aggregated particles at 45° C., 20 parts of the amorphous polyester resin particle dispersion (2-1) was added and the mixture was held for 10 minutes to form second aggregated particles.

[0176] -Combining process- A 0.1 N aqueous solution of sodium hydroxide was added to the dispersion containing the second aggregated particles to adjust the pH to 8.7, and the liquid temperature was raised to 84°C and maintained for 80 minutes. The liquid was then cooled to 20°C at a rate of 20°C / min, and the solid content was filtered, washed with ion-exchanged water, and dried. The dried product was sieved to obtain toner particles (1).

[0177] [Preparation of externally added toner] 1.5 parts of hydrophobic silica particles (product number: RY50, Nippon Aerosil Co., Ltd.) were added to 100 parts of the toner particles (1), and mixed using a sample mill at 10,000 rpm for 30 seconds. After that, the mixture was sieved using a vibrating sieve with 45 μm openings to obtain an externally added toner.

[0178] [Preparation of carrier (1)] A dispersion was prepared by dispersing 14 parts of toluene, 5 parts of a cyclohexyl methacrylate-monoethylaminoethyl methacrylate copolymer (mass ratio 95:5, weight average molecular weight 60,000), and 0.2 parts of carbon black (product number: VXC-72, Cabot Japan Co., Ltd.) in a sand mill. The dispersion and 100 parts of ferrite particles (average particle size 35 μm) were placed in a vacuum degassing kneader, and the mixture was stirred under reduced pressure and dried to obtain carrier (1).

[0179] [Preparation of developer] 8 parts of the externally added toner and 92 parts of the carrier (1) were placed in a V-blender and stirred for 20 minutes, after which the mixture was sieved through a sieve with 212 μm openings to obtain a developer.

[0180] <Examples 2 to 18, Comparative Examples 1 and 2> Toner particles of each example were prepared in the same manner as in Example 1, except that the type of amorphous polyester resin particle dispersion (1) and the type of amorphous polyester resin particle dispersion (2) were changed as shown in Table 3, and the amounts of anionic surfactant and ammonium sulfate aqueous solution added and the pH in the coalescence step were changed as shown in Table 3. Externally added toner and developer were produced in the same manner as in Example 1 using the toner particles of each example.

[0181] <Evaluation> [Toner particle size distribution] The particle size distribution of the toner particles was measured using a Coulter Multisizer 4e (Beckman Coulter, Inc.). The volume average particle size D50v, which is the cumulative 50% from the smallest diameter side in the volume-based particle size distribution, was calculated. D16v, which is the cumulative 16% from the smallest diameter side, and D84v, which is the cumulative 84% from the smallest diameter side, were calculated, and the particle size distribution index GSDv was calculated using the following formula (2). The measurement results are shown in Table 3. Formula (2): GSDv=(D84v / D16v) 1 / 2

[0182] [Analysis of sulfur element] The toner particles before external addition were used as a sample to carry out the above-mentioned fluorescent X-ray analysis to determine the content (mass %) of sulfur element. The measurement results are shown in Table 3.

[0183] [Evaluation of image density unevenness] A4-sized plain paper (Fujifilm Business Innovation Co., Ltd., C2 paper) was placed in an environment with a temperature of 25°C and a relative humidity of 50% for one week to regulate the temperature and humidity. The developer was filled into the developing unit of a modified image forming device "700 Digital Color Press" (Fujifilm Business Innovation Co., Ltd.) and seasoned overnight in an environment of 25°C temperature and 50% relative humidity. Next, a 20cm x 20cm patch image with an image density of 1.6 was formed on temperature and humidity-controlled plain paper, and the image formation conditions were stored in the image forming device. The image density was measured using an X-Rite 939 reflection spectrodensitometer (aperture 4mm, X-Rite Corporation). After seasoning the image forming device for one day in an environment at a temperature of 28°C and a relative humidity of 90%, the transfer voltage was set to 1200V in an environment at a temperature of 28°C and a relative humidity of 90%, and a 20cm x 20cm patch image was printed on temperature- and humidity-controlled plain paper. The image density was measured at five points, and the difference between the maximum and minimum image density (Δimage density) was classified as follows. The evaluation results are shown in Table 3.

[0184] A:Δ image density 0.05 or less B+:Δ image density more than 0.05, less than 0.10 B:Δ image density over 0.10, 0.15 or less B-:Δ image density more than 0.15, less than 0.20 C:Δ image density more than 0.20, less than 0.25 D:Δ image density over 0.25

[0185] [Table 3]

[0186] The manufacturing method of the toner for developing electrostatic images, the toner for developing electrostatic images, the electrostatic image developer, the toner cartridge, the process cartridge, the image forming apparatus, and the image forming method of the present disclosure include the following aspects.

[0187] (((1))) a step of aggregating the amorphous resin particles (1) in a resin particle dispersion liquid containing amorphous resin particles (1) obtained by melt-mixing an amorphous resin and adding an aqueous medium to the amorphous resin to form first aggregated particles; forming second aggregated particles by adhering the amorphous resin particles (2) to the surfaces of the first aggregated particles in a resin particle dispersion containing the first aggregated particles and amorphous resin particles (2) obtained by dissolving and mixing an amorphous resin and an organic solvent, and adding an aqueous medium to the amorphous resin particles (2) to granulate the particles; and heating the dispersion liquid containing the second aggregated particles to fuse and coalesce the second aggregated particles to form toner particles, the toner particles contain sulfur element, and the content of the sulfur element contained in the toner particles is 0.05% by mass or more and 0.20% by mass or less with respect to the mass of the toner particles; A method for producing a toner for developing electrostatic images. (((2))) the amorphous resin particles (1) contain elemental sulfur, the value obtained by dividing the content of the sulfur element contained in the toner particles (mass ratio to the mass of the toner particles) by the content of the sulfur element contained in the amorphous resin particles (1) (mass ratio of the amorphous resin particles (1) to the mass of the amorphous resin) is 1 or less; A method for producing the toner for developing electrostatic images according to (((1))). (((3))) the toner particles contain a nitrogen element, the value (ppm / mass%) obtained by dividing the nitrogen element content (ppm) on the surface of the toner particles by the sulfur element content (mass%) contained in the toner particles is 50 or less; The method for producing a toner for developing electrostatic images according to (((1))) or (((2))). (((4))) A toner for developing electrostatic images, produced by the method for producing a toner for developing electrostatic images according to any one of (((1))) to (((3))). (((5))) An electrostatic image developer comprising the toner for developing electrostatic images according to (((4))). (((6))) (((4))) is contained in the electrostatic image developing toner, A toner cartridge that is detachably attached to an image forming device. (((7))) a developing device that contains the electrostatic image developer according to (((5))) and develops an electrostatic image formed on the surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge is detachably mounted in an image forming apparatus. (((8))) an image carrier; a charging device that charges the surface of the image carrier; an electrostatic image forming device for forming an electrostatic image on the charged surface of the image carrier; a developing device that contains the electrostatic image developer according to (((5))) and develops the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer; a transfer device that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing device for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising: (((9))) a charging step of charging the surface of the image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to (((5))); a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; An image forming method comprising the steps of:

[0188] According to (((1))), a manufacturing method for manufacturing a toner for developing electrostatic images is provided that suppresses the occurrence of image density unevenness compared to manufacturing methods in which the content of sulfur element contained in the toner particles is less than 0.05% by mass or more than 0.20% by mass relative to the mass of the toner particles. According to (((2))), a production method for producing a toner for developing electrostatic images is provided that suppresses the occurrence of uneven image density, compared to a production method in which the value obtained by dividing the content of elemental sulfur contained in the toner particles by the content of elemental sulfur contained in the amorphous resin particles (1) exceeds 1. According to (((3))), a manufacturing method for manufacturing a toner for developing electrostatic images is provided that suppresses the occurrence of uneven image density, compared to a manufacturing method in which the value (ppm / mass%) obtained by dividing the nitrogen element content (ppm) on the surface of the toner particles by the sulfur element content (mass%) contained in the toner particles exceeds 50. According to (((4))), an electrostatic image developing toner is provided which suppresses the occurrence of image density unevenness compared to an electrostatic image developing toner in which the content of sulfur element contained in the toner particles is less than 0.05 mass % or more than 0.20 mass % relative to the mass of the toner particles. According to (((5))), an electrostatic image developer is provided which suppresses the occurrence of image density unevenness compared to an electrostatic image developer containing an electrostatic image developing toner in which the content of sulfur element contained in the toner particles is less than 0.05 mass % or more than 0.20 mass % relative to the mass of the toner particles. According to (((6))), a toner cartridge is provided which suppresses the occurrence of uneven image density compared to a toner cartridge containing electrostatic image developing toner in which the content of sulfur element contained in the toner particles is less than 0.05% by mass or more than 0.20% by mass relative to the mass of the toner particles. According to (((7))), a process cartridge is provided which suppresses the occurrence of uneven image density compared to a process cartridge containing an electrostatic image developer including a toner for developing electrostatic images, the content of sulfur element contained in the toner particles being less than 0.05% by mass or more than 0.20% by mass relative to the mass of the toner particles. According to (((8))), an image forming apparatus is provided which suppresses the occurrence of uneven image density compared to an image forming apparatus containing an electrostatic image developer including a toner for developing electrostatic images, the toner particles of which contain less than 0.05% by mass or more than 0.20% by mass of sulfur element, relative to the mass of the toner particles. According to (((9))), an image forming method is provided which suppresses the occurrence of image density unevenness compared to an image forming method using an electrostatic image developer containing an electrostatic image developing toner in which the content of sulfur element contained in the toner particles is less than 0.05 mass % or more than 0.20 mass % relative to the mass of the toner particles. [Explanation of symbols]

[0189] 1Y, 1M, 1C, 1K Photoconductor (an example of an image carrier) 2Y, 2M, 2C, 2K Charging roll (example of charging device) 3. Exposure device (an example of an electrostatic image forming device) 3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing device (example of developing device) 5Y, 5M, 5C, 5K Primary transfer roll (an example of a primary transfer device) 6Y, 6M, 6C, 6K Photoconductor cleaning device (example of cleaning device) 8Y, 8M, 8C, 8K toner cartridges 10Y, 10M, 10C, 10K image forming units 20 Intermediate transfer belt (an example of an intermediate transfer body) 22 Drive Roll 24 Support Roll 26 Secondary transfer roll (an example of a secondary transfer device) 28 Fixing device (example of fixing device) 30 Intermediate transfer body cleaning device P Recording paper (an example of a recording medium)

[0190] 107 Photosensitive body (an example of an image carrier) 108 Charging roll (an example of a charging device) 109 Exposure device (an example of an electrostatic image forming device) 111 Developing device (an example of a developing device) 112 Transcription device (an example of a transcription device) 113 Photosensitive drum cleaning device (an example of a cleaning device) 115 Fixing device (an example of a fixing device) 116 Mounting Rail 117 Cabinet 118 Exposure opening 200 Process Cartridge 300 Recording paper (an example of a recording medium) P Recording paper (an example of a recording medium)

Claims

1. a step of aggregating the amorphous resin particles (1) in a resin particle dispersion liquid containing amorphous resin particles (1) obtained by melt-mixing an amorphous resin and adding an aqueous medium to the amorphous resin to form first aggregated particles; forming second aggregated particles by adhering the amorphous resin particles (2) to surfaces of the first aggregated particles in a resin particle dispersion containing the first aggregated particles and amorphous resin particles (2) obtained by dissolving and mixing an amorphous resin and an organic solvent, and adding an aqueous medium to the amorphous resin particles (2) to granulate the particles; and heating the dispersion liquid containing the second aggregated particles to fuse and coalesce the second aggregated particles to form toner particles, the toner particles contain sulfur element, and the content of the sulfur element contained in the toner particles is 0.05% by mass or more and 0.20% by mass or less with respect to the mass of the toner particles; A method for producing a toner for developing electrostatic images.

2. The amorphous resin particles (1) contain sulfur element, the value obtained by dividing the content of the sulfur element contained in the toner particles (mass ratio to the mass of the toner particles) by the content of the sulfur element contained in the amorphous resin particles (1) (mass ratio of the amorphous resin particles (1) to the mass of the amorphous resin) is 1 or less; A method for producing the toner for developing electrostatic images according to claim 1.

3. the toner particles contain a nitrogen element, a value (ppm / mass%) obtained by dividing the nitrogen element content (ppm) on the surface of the toner particles by the sulfur element content (mass%) contained in the toner particles is 50 or less; 3. A method for producing the toner for developing electrostatic images according to claim 1 or 2.

Images