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

Abstract

To provide a toner for electrostatic image development that exhibits excellent fogging suppression and low-temperature fixing properties. [Solution] A toner for developing electrostatic images, comprising toner particles containing amorphous polyester resin and styrene (meth)acrylic resin, wherein the toner particles have spherical domains A of styrene (meth)acrylic resin that are insoluble in tetrahydrofuran and spherical domains B of styrene (meth)acrylic resin that are soluble in tetrahydrofuran, the glass transition temperature Tg1 of the spherical domain A of styrene (meth)acrylic resin being 0°C or more and 35°C or less, and when the glass transition temperature of the spherical domain B of styrene (meth)acrylic resin is Tg2, the value of Tg2-Tg1 is 20°C or more and 55°C or less.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses toner particles containing a binder resin containing a polyester resin, a release agent containing a hydrocarbon wax, and a styrene (meth) acrylic resin, wherein 70% or more of the total release agent is present within 800 nm from the surface of the toner particles, the styrene (meth) acrylic resin forms domains having an average diameter of 0.3 μm or more and 0.8 μm or less in the toner particles, and the number ratio of the domains contained in the range of the average diameter ± 0.1 μm is 65% or more. A toner for electrostatic charge image development is disclosed.

[0003] Patent Document 2 discloses a toner for electrostatic charge image development containing toner base particles containing at least a binder resin, wherein the toner base particles are toner base particles formed by aggregation and fusion of fine particles of the binder resin and seed polymerization fine particles, the seed polymerization fine particles have an outer shell and a seed part, the difference (Tg2 - Tg1) between the glass transition temperature Tg1 of the seed part and the glass transition temperature Tg2 of the outer shell is 50°C or more, the binder resin contains, as a main component, an amorphous resin having a glass transition temperature of Tgm, and the Tgm is higher than the Tg1. A toner for electrostatic charge image development is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] This embodiment aims to provide a toner for electrostatic image development that exhibits superior fogging suppression and low-temperature fixing properties compared to cases where the toner particles have spherical domains A of styrene(meth)acrylic resin that are insoluble in tetrahydrofuran and spherical domains B of styrene(meth)acrylic resin that are soluble in tetrahydrofuran, and the glass transition temperature Tg1 of the spherical domains A of styrene(meth)acrylic resin is less than 0°C or greater than 35°C, or where the glass transition temperature Tg2 of the spherical domains B of styrene(meth)acrylic resin is Tg2, and the value of Tg2-Tg1 is less than 20°C or greater than 55°C. [Means for solving the problem]

[0006] The following embodiments are included as specific means for solving the aforementioned problems. <1> A toner for developing electrostatic images, comprising toner particles containing an amorphous polyester resin and a styrene (meth)acrylic resin, wherein the toner particles have a spherical domain A of styrene (meth)acrylic resin that is insoluble in tetrahydrofuran and a spherical domain B of styrene (meth)acrylic resin that is soluble in tetrahydrofuran, the glass transition temperature Tg1 of the spherical domain A of styrene (meth)acrylic resin is 0°C or more and 35°C or less, and when the glass transition temperature of the spherical domain B of styrene (meth)acrylic resin is Tg2, the value of Tg2-Tg1 is 20°C or more and 55°C or less. <2> When the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is W1 by mass, and the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin is W2 by mass, the following conditions must be met: 0.3 ≤ W1 / W2 ≤ 3.0 <1> Toner for developing electrostatic images as described above. <3> When the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is W1 by mass, and the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin is W2 by mass, the value of 5 ≤ W1 + W2 ≤ 40 is satisfied. <1> or <2> Toner for developing electrostatic images as described above. <4> The toner particles contain styrene(meth)acrylic resin that constitutes the spherical domain A of the styrene(meth)acrylic resin, which is 1.5% by mass or more and 30% by mass or less. <1> ~ <3> A toner for developing electrostatic images, as described in one of the following. <5> The toner particles contain styrene(meth)acrylic resin that constitutes the spherical domain B of the styrene(meth)acrylic resin, which is 1.5% by mass or more and 25% by mass or less. <1> ~ <4> A toner for developing electrostatic images, as described in one of the following. <6> The domain diameter of the spherical domain A of the styrene(meth)acrylic resin is 50 nm or more and 300 nm or less. <1> ~ <5> A toner for developing electrostatic images, as described in one of the following. <7> The domain diameter of the spherical domain B of the styrene(meth)acrylic resin is 300 nm or more and 800 nm or less. <1> ~ <6> A toner for developing electrostatic images, as described in one of the following. <8> The domain diameter of the spherical domain A of the styrene(meth)acrylic resin is smaller than the domain diameter of the styrene(meth)acrylic resin B. <1> ~ <7> A toner for developing electrostatic images, as described in one of the following. <9> The acid value of the amorphous polyester resin is 6 mg KOH / g or more and 16 mg KOH / g or less. <1> ~ <8> A toner for developing electrostatic images, as described in one of the following. <10> <1> ~ <9> A electrostatic image developer containing an electrostatic image developing toner as described in any one of the following. <11> <1> ~ <9> A toner cartridge that contains the electrostatic image developing toner described in any one of the above, and is attached to and detached from an image forming apparatus. <12> <10> A process cartridge that is attached to and detached from an image forming apparatus, comprising a developing device that contains the electrostatic image developer described above and develops an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer. <13> An image holder, a charging device for charging the surface of the image holder, and an electrostatic image forming device for forming an electrostatic image on the charged surface of the image holder, <10> An image forming apparatus comprising: a developing device that contains the electrostatic image developer described in [reference] and develops the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer; a transferring device that transfers the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing device that fixes the toner image transferred to the surface of the recording medium. <14> A charging step of charging the surface of the image holder, and a static charge image forming step of forming a static charge image on the charged surface of the image holder, <10> An image forming method comprising: a developing step of developing an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer described in [reference]; a transfer step of transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium. [Effects of the Invention]

[0007] <1> According to the present invention, a toner for electrostatic image development is provided in which the toner particles have spherical domains A of styrene(meth)acrylic resin that are insoluble in tetrahydrofuran and spherical domains B of styrene(meth)acrylic resin that are soluble in tetrahydrofuran, and the Tg1 of the spherical domains A of styrene(meth)acrylic resin is less than 0°C or greater than 35°C, or the value of Tg2-Tg1 is less than 20°C or greater than 55°C when the glass transition temperature of the spherical domains B of styrene(meth)acrylic resin is Tg2, and the fogging suppression and low-temperature fixing properties are superior to those of the present invention. <2> According to the invention, a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the value of W1 / W2 is less than 0.3 or greater than 3.0. <3> According to the invention, a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the value of W1 + W2 is less than 5 or greater than 40. <4> According to the invention, a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing properties compared to cases where the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is less than 1.5% by mass or more than 30% by mass. <5> According to the invention, a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing properties compared to cases where the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin in the toner particles is less than 1.5% by mass or more than 25% by mass. <6> According to the invention, a toner for developing electrostatic images is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the domain diameter of the spherical domain A of the styrene (meth)acrylic resin is less than 50 nm or greater than 300 nm. <7> According to the invention, a toner for developing electrostatic images is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the domain diameter of the spherical domain B of the styrene (meth)acrylic resin is less than 300 nm or greater than 800 nm. <8> According to the invention, a toner for developing electrostatic images is provided that is superior in terms of fogging suppression and low-temperature fixing performance compared to the case where the domain diameter of the spherical domain A of the styrene (meth)acrylic resin is equal to or greater than the domain diameter of the spherical domain B of the styrene (meth)acrylic resin. <9> According to the invention, a toner for developing electrostatic images is provided that is superior in fogging suppression and low-temperature fixing properties compared to cases where the acid value of the amorphous polyester resin is less than 6 mg KOH / g or greater than 16 mg KOH / g. According to the invention related to <10>, <11>, <12>, <13> or <14>, the toner particles have a spherical domain A of a styrene (meth)acrylic resin having a crosslinked structure and insoluble in tetrahydrofuran, and a spherical domain B of a styrene (meth)acrylic resin soluble in tetrahydrofuran. When the glass transition temperature Tg1 of the spherical domain A of the styrene (meth)acrylic resin is less than 0°C or more than 35°C, or when the glass transition temperature of the spherical domain B of the styrene (meth)acrylic resin is Tg2, and the value of Tg2 - Tg1 is less than 20°C or more than 55°C, compared with the case of using an electrostatic charge image developing toner, an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus or an image forming method excellent in fog suppression property and low temperature fixing property is provided.

Brief Description of Drawings

[0008] [Figure 1] It is a schematic configuration diagram showing an image forming apparatus according to this embodiment. [Figure 2] It is a schematic configuration diagram showing a process cartridge according to this embodiment.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of this embodiment will be described. These descriptions and examples are illustrative of the embodiment and do not limit the scope of the embodiment.

[0010] In this embodiment, the numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described step by step in this embodiment, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in this embodiment, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0011] In this embodiment, the term "step" includes not only an independent step but also a step whose purpose can be achieved even if it cannot be clearly distinguished from other steps.

[0012] In this embodiment, each component may contain a plurality of corresponding substances. When referring to the amount of each component in the composition, if there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition. In this embodiment, the particles corresponding to each component may contain a plurality of types. When there are a plurality of types of particles corresponding to each component in the composition, the particle diameter of each component means a value for the mixture of the plurality of types of particles present in the composition, unless otherwise specified.

[0013] In this embodiment, "(meth)acryl" is an expression that includes both acryl and methacryl, and "(meth)acrylate" is an expression that includes both acrylate and methacrylate. In this embodiment, the "toner for electrostatic charge image development" is also referred to as "toner".

[0014] <Toner for electrostatic charge image development> The toner for electrostatic charge image development according to this embodiment has toner particles containing an amorphous polyester resin and a styrene (meth)acrylic resin, and the toner particles have a spherical domain A of a styrene (meth)acrylic resin that is insoluble in tetrahydrofuran and a spherical domain B of a styrene (meth)acrylic resin that is soluble in tetrahydrofuran. The glass transition temperature Tg1 of the spherical domain A of the styrene (meth)acrylic resin is 0°C or higher and 35°C or lower, and when the glass transition temperature of the spherical domain B of the styrene (meth)acrylic resin is Tg2, the value of Tg2 - Tg1 is 20°C or higher and 55°C or lower.

[0015] Conventional toners have used polyester resin as a binder to ensure low-temperature fixation, but polyester resin is highly absorbent, and when printed after being left in a high-humidity environment for a long period of time, fogging occurs. "Fogging" is a phenomenon in which unintended dot-like images appear on the image-forming surface of the recording medium. While incorporating styrene (meth)acrylic resin particles into polyester resin toner can suppress fogging, the low affinity between polyester resin and styrene (meth)acrylic resin causes styrene (meth)acrylic resin domains to form in the toner. These styrene (meth)acrylic resin domains are also present in the image after fixing, and when the fixed image is folded, cracks are likely to occur at the interface between the styrene (meth)acrylic resin domains and the polyester resin, making it difficult to ensure low-temperature fixing. Therefore, achieving both fogging suppression and low-temperature fixing was challenging.

[0016] In the electrostatic image developing toner according to this embodiment, the toner particles have spherical domains A of styrene(meth)acrylic resin that are insoluble in tetrahydrofuran and spherical domains B of styrene(meth)acrylic resin that are soluble in tetrahydrofuran. The Tg1 of the spherical domains A of styrene(meth)acrylic resin is 0°C to 35°C, and when the glass transition temperature of the spherical domains B of styrene(meth)acrylic resin is Tg2, the value of Tg2-Tg1 is 20°C to 55°C. As a result, a portion of the spherical domains B of styrene(meth)acrylic resin are exposed on the surface of the toner particles, the toner's charge does not decrease easily, and fogging is suppressed. During fixing, the molten spherical domains B of styrene(meth)acrylic resin are incorporated into the network structure of the spherical domains A of styrene(meth)acrylic resin which have a cross-linked structure, so that the styrene(meth)acrylic resin domains B are less likely to be present in the fixed image. Furthermore, because the spherical domains A of styrene(meth)acrylic resin themselves are flexible, excellent low-temperature fixing properties are achieved and fogging is suppressed.

[0017] The configuration of the electrostatic image developing toner according to this embodiment will be described in detail below.

[0018] [Toner particles] The toner particles consist of a binder resin and, if necessary, a colorant, a release agent, and other additives.

[0019] (Spherical domains A and B of styrene(meth)acrylic resin) The toner particles contain styrene (meth)acrylic resin. Furthermore, the toner particles have spherical domains A of styrene(meth)acrylic resin that are insoluble in tetrahydrofuran, and spherical domains B of styrene(meth)acrylic resin that are soluble in tetrahydrofuran, the glass transition temperature Tg1 of spherical domain A of styrene(meth)acrylic resin is 0°C or higher and 35°C or lower, and when the glass transition temperature Tg2 of spherical domain B of styrene(meth)acrylic resin is taken as Tg2, the value of Tg2-Tg1 is 20°C or higher and 55°C or lower.

[0020] -Extraction of spherical domain A of styrene(meth)acrylic resin, which is insoluble in tetrahydrofuran- (1) Weigh 0.25 g of toner, add 40 mL of tetrahydrofuran (THF) to it, and mix and stir for 3 hours. (2) The mixture obtained in (1) is separated using a centrifuge at 2,000 rpm for 30 minutes. (3) Remove the precipitate obtained after centrifugation in (2), wash it with methanol, and remove the THF. (4) Transfer the washed precipitate to an aluminum dish or similar container and evaporate and dry the methanol component in a vacuum dryer heated to 50°C. (5) Add 40 mL of THF to the dried substance and mix and stir for 1 hour while heating to 85°C. (6) The mixture obtained in (5) is filtered without cooling to remove the THF-insoluble components. The THF-insoluble components are transferred to an aluminum dish or the like, and the THF components are evaporated and dried in a vacuum dryer heated to 50°C to obtain spherical domains A of styrene(meth)acrylic resin isolated from the toner.

[0021] -Glass transition temperatures Tg1 and Tg2- The glass transition temperature Tg1 of the spherical domain A of the styrene(meth)acrylic resin is 0°C or higher and 35°C or lower. From the viewpoint of suppressing clouding and low-temperature fixing, it is preferably 10°C or higher and 35°C or lower, more preferably 14°C or higher and 30°C or lower, and particularly preferably 16°C or higher and 25°C or lower.

[0022] The glass transition temperature Tg2 of the spherical domain B of the styrene(meth)acrylic resin is preferably 35°C to 70°C, more preferably 40°C to 65°C, and particularly preferably 50°C to 60°C, from the viewpoint of suppressing fogging and low-temperature fixing.

[0023] In the toner particles of this embodiment, the Tg2-Tg1 value is 20°C to 55°C, preferably 25°C to 55°C, more preferably 30°C to 50°C, and particularly preferably 35°C to 45°C, from the viewpoint of fogging suppression and low-temperature fixing properties.

[0024] Furthermore, the fact that spherical domains A and B are made of styrene (meth)acrylic resin can be determined by nuclear magnetic resonance (NMR) measurement of the toner particles. In this embodiment, the method for measuring the Tg1 of spherical domain A of styrene (meth)acrylic resin is to measure the tetrahydrofuran (THF) insoluble content of toner particles using a differential thermal analysis (DSC) device and then measure the Tg1. Furthermore, in this embodiment, the method for measuring the Tg2 of the spherical domain B of the styrene(meth)acrylic resin involves calculating the monomer composition ratio by nuclear magnetic resonance (NMR) measurement of toner particles and then calculating Tg2 using the FOX formula. That is, the measurement and calculation are performed by the following method.

[0025] First, the ratio of constituent monomers in styrene(meth)acrylic resin is quantified using NMR analysis. Then, the glass transition temperature Tg2 is calculated using the Fox equation from the ratio of each constituent monomer determined above. Specifically, it is as follows: The glass transition temperature of a (meth)acrylate monomer homopolymer is TgA(K), the (meth)acrylate monomer ratio (mass percentage: mass%) is WA, the glass transition temperature of a styrene monomer homopolymer is TgS(K), the styrene monomer ratio (mass percentage: mass%) is WA, and the target glass transition temperature Tg0(K) is given by the following FOX equation. FOX formula: 1 / Tg0=(WA / TgA)+(WS / TgS) Using the Fox formula, substitute the glass transition temperatures and ratios of each (meth)acrylate monomer and the styrene monomer in the entire resin particle or on the surface of the resin particle, and calculate Tg0 = "the target glass transition temperature Tg1 or Tg2" using the Fox formula. Furthermore, the glass transition temperatures of (meth)acrylate monomer homopolymers and styrene monomer homopolymers may be based on measured values ​​or catalog values.

[0026] The adjustment of Tg1, Tg2, etc., in the spherical domains A and B of styrene (meth)acrylic resin can be achieved by adjusting the monomer composition of the copolymer and the amount of crosslinking agent.

[0027] -Styrene (meth)acrylic resin content- The content W1 of styrene(meth)acrylic resin constituting the spherical domain A of the styrene(meth)acrylic resin is preferably 1.5% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and particularly preferably 5% by mass or more and 15% by mass or less, based on the total mass of the toner particles, from the viewpoint of suppressing fogging and low-temperature fixing properties. The content W2 of styrene(meth)acrylic resin constituting the spherical domain B of the styrene(meth)acrylic resin is preferably 1.5% to 25% by mass, more preferably 3% to 18% by mass, and particularly preferably 5% to 12% by mass, based on the total mass of the toner particles, from the viewpoint of suppressing fogging and low-temperature fixing properties. Further, the content W1 of the styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin is preferably more than the content W2 of the styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin from the viewpoints of fogging suppression and low-temperature fixing property.

[0028] Also, from the viewpoints of fogging suppression and low-temperature fixing property, the value of W1 / W2 is preferably 0.3 or more and 3.0 or less, more preferably 0.8 or more and 2.5 or less, and particularly preferably more than 1.0 and 2.0 or less. In other words, from the viewpoints of fogging suppression and low-temperature fixing property, the value of W1 / W2 preferably satisfies formula A-1, more preferably satisfies formula A-2, and particularly preferably satisfies formula A-3. 0.3 ≦ W1 / W2 ≦ 3.0 Formula A-1 0.8 ≦ W1 / W2 ≦ 2.5 Formula A-2 1.0 < W1 / W2 ≦ 2.0 Formula A-3

[0029] Also, from the viewpoints of fogging suppression and low-temperature fixing property, the value of W1 + W2 is preferably 5 mass% or more and 40 mass% or less, more preferably 10 mass% or more and 30 mass% or less, and particularly preferably 15 mass% or more and 25 mass% or less. In other words, from the viewpoints of fogging suppression and low-temperature fixing property, the value of W1 + W2 preferably satisfies formula B-1, more preferably satisfies formula B-2, and particularly preferably satisfies formula B-3. The unit of the numerical value in the following formula is mass%. 5 ≦ W1 + W2 ≦ 40 Formula B-1 10 ≦ W1 + W2 ≦ 30 Formula B-2 15 ≦ W1 + W2 ≦ 25 Formula B-3

[0030] -Domain diameters of the spherical domains A and B of the styrene (meth)acrylic resin- The toner particles have a spherical domain A of a styrene (meth)acrylic resin and a spherical domain B of the styrene (meth)acrylic resin. The shape of the domain may be spherical, and may be a perfect sphere, ellipsoid, barrel-shaped, oval-shaped, irregularly shaped sphere, or the like. The domain diameter distribution of the aforementioned domains has two peaks, one in the range of 50 nm to 300 nm and the other in the range of 300 nm to 800 nm. The domain diameter of the spherical domain A of the styrene(meth)acrylic resin is preferably 50 nm to 300 nm, more preferably 80 nm to 280 nm, and particularly preferably 100 nm to 250 nm, from the viewpoint of suppressing cover and low-temperature fixing properties. The domain diameter of the spherical domain B of the styrene(meth)acrylic resin is preferably 300 nm to 800 nm, more preferably 300 nm to 700 nm, and particularly preferably 350 nm to 600 nm, from the viewpoint of suppressing cover and low-temperature fixing properties. Furthermore, from the viewpoint of suppressing clouding and low-temperature fixing properties, it is preferable that the domain diameter of spherical domain A of the styrene(meth)acrylic resin is smaller than the domain diameter of spherical domain B of the styrene(meth)acrylic resin.

[0031] In this embodiment, the method for measuring the domain diameter involves observing 50 low-Tg domains A and 50 high-Tg domains B in the cross-section of a toner particle using atomic force microscopy-infrared spectroscopy (AFM-IR), and measuring the maximum length of each domain. The arithmetic mean of these maximum lengths is defined as the domain diameter. Furthermore, to prepare cross-sectional samples of toner particles, the toner particles are embedded in a bisphenol A type liquid epoxy resin and a hardening agent, and then a cutting sample is prepared. Next, the cutting sample is cut at -100°C using a cutting machine with a diamond knife, such as a LEICA ultramicrotome (manufactured by Hitachi High-Technologies Corporation), to prepare a sample for cross-sectional observation.

[0032] -Monomer composition of styrene(meth)acrylic resin- The styrene (meth)acrylic resin in this embodiment includes, for example, resins obtained by polymerizing styrene monomers and (meth)acrylic monomers such as (meth)acrylate monomers by radical polymerization.

[0033] Examples of styrene monomers include styrene, α-methylstyrene, vinylnaphthalene, alkyl-substituted styrenes having alkyl chains such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene, halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene, and fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene. Among these, styrene or α-methylstyrene is preferred.

[0034] Examples of (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, and (meth)acrylic acid Examples include amyl, neopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, biphenyl (meth)acrylate, diphenylethyl (meth)acrylate, t-butylphenyl (meth)acrylate, terphenyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-carboxyethyl (meth)acrylate.

[0035] As for (meth)acrylate monomers, from the viewpoint of ease of adjusting the Tg1 and Tg2 of styrene (meth)acrylic resin, (meth)acrylate compounds having an alkyl group with 2 to 12 carbon atoms (also called "number of carbon atoms") are preferred, (meth)acrylate compounds having an alkyl group with 2 to 10 carbon atoms are more preferred, and (meth)acrylate compounds having an alkyl group with 4 to 7 carbon atoms are particularly preferred. Among the (meth)acrylate monomers, n-butyl (meth)acrylate is particularly preferred from the viewpoint of the ease of adjusting the Tg1 and Tg2 of the styrene (meth)acrylic resin. Furthermore, from the viewpoint of ease of adjusting Tg1 and Tg2, it is preferable that the proportion of (meth)acrylate monomers in all monomers constituting spherical domain A of the styrene (meth)acrylic resin is greater than the proportion of (meth)acrylate monomers in all monomers constituting spherical domain B of the styrene (meth)acrylic resin.

[0036] The styrene(meth)acrylic resin constituting the spherical domain A of the styrene(meth)acrylic resin preferably has a cross-linked structure. Furthermore, the styrene(meth)acrylic resin constituting the spherical domain B of the styrene(meth)acrylic resin may have a cross-linked structure. Examples of crosslinking agents that form crosslinked structures include: aromatic polyfunctional vinyl compounds such as divinylbenzene and divinylnaphthalene; polyvinyl esters of aromatic polycarboxylic acids such as divinyl phthalate, divinyl isophthalate, divinyl terephthalate, divinyl homophthalate, divinyl trimesicate, trivinyl trimesicate, divinyl naphthalenedicarboxylate, and divinyl biphenylcarboxylate; divinyl esters of nitrogen-containing aromatic compounds such as divinyl pyridinedicarboxylate; vinyl esters of unsaturated heterocyclic carboxylic acid compounds such as vinyl pyromutinate, vinyl furanate, vinyl pyrrole-2-carboxylate, and vinyl thiophenecarboxylate; butanediol diacrylate, butanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, octanediol diacrylate, octanediol dimethacrylate, nonanediol diacrylate, nonanediol dimethacrylate, decanediol diacrylate, decanediol dimethacrylate Examples include (meth)acrylic acid esters of linear polyhydric alcohols such as thacrylate, dodecanediol diacrylate, and dodecanediol dimethacrylate; (meth)acrylic acid esters of branched and substituted polyhydric alcohols such as neopentyl glycol dimethacrylate and 2-hydroxy,1,3-diacryloxypropane; and polyfunctional vinyl esters of polycarboxylic acids such as polyethylene glycol di(meth)acrylate, polypropylene polyethylene glycol di(meth)acrylate, divinyl succinate, divinyl fumarate, vinyl maleate, divinyl maleate, divinyl diglycolate, vinyl itaconate, divinyl itaconate, divinyl acetonedicarboxylic acid, divinyl glutarate, divinyl 3,3'-thiodipropionate, divinyl trans-aconitate, trivinyl trans-aconitate, divinyl adipic acid, divinyl pimephosphate, divinyl suberate, divinyl azelaate, divinyl sebacate, divinyl dodecanediate, and divinyl brassylate. Crosslinking agents may be used individually or in combination of two or more types.

[0037] Among these, it is preferable to use alkylene glycol diacrylate having alkylene chains with 6 or more carbon atoms as the crosslinking agent. In other words, the resin particles have constituent units derived from alkylene glycol diacrylate, and it is preferable that the alkylene chains in the alkylene glycol diacrylate have 6 or more carbon atoms. By using a resin that has constituent units derived from alkylene glycol diacrylate and whose alkylene chain has 6 or more carbon atoms, the crosslinking density becomes low (i.e., the distance between crosslinking points becomes long), which can suppress the resin from becoming excessively elastic.

[0038] From the viewpoint of adjusting the crosslinking density to an appropriate range, the number of carbon atoms in the alkylene chain of alkylene glycol diacrylate is preferably 6 or more, more preferably 6 to 12, and even more preferably 8 to 12. More specific examples of alkylene glycol diacrylate include 1,6-hexanediol acrylate, 1,6-hexanediol methacrylate, 1,8-octanediol diacrylate, 1,8-octanediol dimethacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, 1,12-dodecanediol diacrylate, and 1,12-dodecanediol dimethacrylate, among which 1,10-decanediol diacrylate and 1,10-decanediol dimethacrylate are preferred. Other crosslinking agents include 2-carboxyethyl acrylate, and it is preferable to use at least one of the aforementioned bifunctional alkyl acrylates.

[0039] The crosslinking agent content is preferably 0.3 parts by mass or more and 5.0 parts by mass or less, more preferably 0.4 parts by mass or more and 3.0 parts by mass or less, and even more preferably 0.5 parts by mass or more and 2.5 parts by mass or less, based on 100 parts by mass of the total of the styrene monomer and (meth)acrylate monomer used to form the styrene (meth)acrylic resin.

[0040] The toner particles may also contain internally added resin particles other than the styrene (meth)acrylic resin particles that constitute the spherical domains A and B of the styrene (meth)acrylic resin.

[0041] <Binding resin> In addition to the styrene (meth)acrylic resin that constitutes the spherical domains A and B of the styrene (meth)acrylic resin, the toner particles also contain an amorphous polyester resin as a binder resin. Furthermore, the toner particles may also contain amorphous polyester resin and binder resins other than styrene(meth)acrylic resin that constitute the spherical domains A and B of the styrene(meth)acrylic resin. Examples of binder resins include vinyl resins consisting of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), or copolymers of two or more of these monomers. Examples of binder resins include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin; mixtures of these with the aforementioned vinyl resins; and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These binding resins may be used individually or in combination of two or more types.

[0042] Polyester resin is preferred as the binder resin. Examples of polyester resins include known amorphous polyester resins. In addition to amorphous polyester resins, crystalline polyester resins may also be used in combination. However, the crystalline polyester resin should be used in an amount of 2% to 40% by mass (preferably 5% to 30% by mass) relative to the total binding resin. Furthermore, from the viewpoint of low-temperature fixation and thermal storage properties, the binder resin preferably contains a crystalline resin, and more preferably contains a crystalline polyester resin.

[0043] Furthermore, the "crystalline nature" of a resin refers to the presence of a clear endothermic peak rather than a stepwise change in endothermic quantity in differential scanning calorimetry (DSC). Specifically, it means that the full width at half maximum of the endothermic peak measured at a heating rate of 10°C / min is within 10°C. On the other hand, "amorphous" resins refer to those with a full width at half maximum exceeding 10°C, exhibiting a stepwise change in endothermic capacity, or lacking a clear endothermic peak.

[0044] Amorphous polyester resin Examples of amorphous polyester resins include condensation polymers of polycarboxylic acids and polyhydric alcohols. The amorphous polyester resin may be a commercially available product or a synthesized one.

[0045] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid (hexenyl succinic acid, octenyl succinic acid, dodecenyl succinic acid, pentadecenyl succinic acid, etc.), adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., with 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. Polycarboxylic acids may be used in combination with dicarboxylic acids, or with trivalent or higher carboxylic acids that have a cross-linked or branched structure. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). Polycarboxylic acids may be used individually or in combination of two or more.

[0046] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyhydric alcohols, and aromatic diols are more preferred. As for the polyhydric alcohol, a trihydric or higher polyhydric alcohol with a cross-linked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. Polyhydric alcohols may be used individually or in combination of two or more types.

[0047] From the viewpoint of suppressing blot formation and low-temperature fixing properties, the acid value of the amorphous polyester resin is preferably 3 mg KOH / g or more and 30 mg KOH / g or less, more preferably 6 mg KOH / g or more and 16 mg KOH / g or less, and particularly preferably 8 mg KOH / g or more and 12 mg KOH / g or less. The acid value of amorphous polyester resin is determined by using an appropriate amount of amorphous polyester resin as a sample and employing the neutralization titration method specified in JIS K0070-1992.

[0048] The glass transition temperature (Tg) of amorphous polyester resin is preferably 50°C to 80°C, and more preferably 50°C to 65°C. The glass transition temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, it is determined by the "extracorporeal glass transition onset temperature" described in the method for determining the glass transition temperature in JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics".

[0049] The weight-average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 to 1,000,000, and more preferably 7,000 to 500,000. The number-average molecular weight (Mn) of the amorphous polyester resin is preferably between 2,000 and 100,000. The molecular weight distribution (Mw / Mn) of the amorphous polyester resin is preferably 1.5 to 100, and more preferably 2 to 60. The weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (GPC). GPC molecular weight measurement is performed using a Tosoh Corporation GPC-HLC-8320GPC analyzer, a Tosoh Corporation TSKgel SuperHM-M (15cm) column, and tetrahydrofuran (THF) solvent. The weight-average molecular weight and number-average molecular weight are calculated from these measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0050] Amorphous polyester resins may be used individually or in combination of two or more types. When using two or more types in combination, for example, a high molecular weight resin and a low molecular weight resin may be used together.

[0051] Amorphous polyester resins can be obtained by well-known manufacturing methods. Specifically, for example, they can be obtained by a method in which the polymerization temperature is set to 180°C or higher and 230°C or lower, and the reaction system is subjected to reduced pressure as needed, while removing water and alcohol generated during condensation. If the monomers of the raw materials do not dissolve or become miscible at the reaction temperature, a high-boiling point solvent may be added as a solubilizer to dissolve them. In this case, the polycondensation reaction should be carried out while distilling off the solubilizer. If there are monomers with poor miscibility, it is advisable to condense the poorly miscible monomers with the acid or alcohol to be polycondensed with them beforehand, and then polycondense them together with the main component.

[0052] • Crystalline polyester resin Crystalline polyester resins include, for example, polycondensates of polycarboxylic acids and polyhydric alcohols. Commercially available crystalline polyester resins may be used, or synthesized resins may be used. Here, in order to easily form a crystalline structure, polycondensates using polymerizable monomers having linear aliphatic structures are preferred over polymerizable monomers having aromatic structures.

[0053] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., phthalic acid, isophthalic acid, terephthalic acid, dibasic acids such as naphthalene-2,6-dicarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). Polycarboxylic acids may be used in combination with dicarboxylic acids, or with trivalent or higher carboxylic acids that have a cross-linked or branched structure. Examples of trivalent carboxylic acids include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2 Examples include 4-naphthalentricarboxylic acid, their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). In addition to these dicarboxylic acids, polycarboxylic acids with sulfonic acid groups and dicarboxylic acids with ethylenic double bonds may also be used in combination. Polycarboxylic acids may be used individually or in combination of two or more.

[0054] Examples of polyhydric alcohols include aliphatic diols (for example, linear aliphatic diols with 2 to 20 carbon atoms in the main chain). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol. Among these, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols. Polyhydric alcohols may be used in combination with diols, including trihydric or higher alcohols that have a cross-linked or branched structure. Examples of trihydric or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. Polyhydric alcohols may be used individually or in combination of two or more types.

[0055] Here, the polyhydric alcohol is preferably composed of 80 mol% or more of aliphatic diols, and more preferably 90 mol% or more.

[0056] The melting temperature of the crystalline polyester resin is preferably 50°C to 100°C, more preferably 55°C to 90°C, and even more preferably 60°C to 85°C. The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in JIS K7121-1987 "Method for determining the transition temperature of plastics".

[0057] The weight-average molecular weight (Mw) of the crystalline polyester resin is preferably between 6,000 and 50,000.

[0058] Crystalline polyester resins can be obtained, for example, by well-known manufacturing methods, similar to amorphous polyesters.

[0059] Furthermore, the polyester resin may be a hybrid resin having a polyester resin segment and a styrene-acrylic copolymer segment.

[0060] The binder resin content is preferably 40% to 95% by mass, more preferably 50% to 90% by mass, and even more preferably 60% to 90% by mass, relative to the total toner particles.

[0061] <Coloring agent> Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzidine yellow, surene yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, balkan orange, Watch Young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, risole red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, ultramarine blue, and calco oil blue. Examples include various pigments such as methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate; inorganic pigments such as titanium compounds, silica, aluminum, and mica; and various dyes such as acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindigo, dioxazine, thiazine, azomethine, indigo, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, and thiazole. The colorant is not limited to substances that absorb in the visible light region. For example, the colorant may be a substance that absorbs in the near-infrared region, a fluorescent colorant, or a colorant that exhibits luminescence. Colorants may be used individually or in combination of two or more types.

[0062] The coloring agent may be a surface-treated coloring agent as needed, and may be used in combination with a dispersant. Furthermore, multiple types of coloring agents may be used in combination.

[0063] The colorant content is preferably 1% to 30% by mass, and more preferably 3% to 15% by mass, relative to the total toner particles.

[0064] <Release agent> Examples of release agents include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral / petroleum-based waxes such as montan wax; and ester waxes such as fatty acid esters and montanic acid esters. However, the release agents are not limited to these.

[0065] The melting temperature of the release agent is preferably 50°C to 110°C, and more preferably 60°C to 100°C. The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in JIS K 7121-1987 "Method for determining the transition temperature of plastics".

[0066] The release agent content is preferably 1% to 20% by mass, and more preferably 4% to 15% by mass, relative to the total toner particles.

[0067] <Other additives> Other additives include well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are included in the toner particles as internal additives.

[0068] <Characteristics of toner particles, etc.> The toner particles may be single-layer toner particles, or they may be toner particles with a so-called core-shell structure, consisting of a core (core particle) and a coating layer (shell layer) that covers the core.

[0069] The volume-average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0070] The average particle size and particle size distribution indices of the toner particles are measured using the Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using the ISOTON-II (manufactured by Beckman Coulter). For measurement, add 0.5 mg to 50 mg of the sample to be measured in 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant. Add this to 100 ml to 150 ml of electrolyte. The electrolyte containing the suspended sample is dispersed in an ultrasonic disperser for 1 minute. The particle size distribution of particles with a diameter of 2 μm to 60 μm is then measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the measured particle size distribution, a cumulative distribution of volume and number is drawn for each divided particle size range (channel) from the smallest diameter side. The particle size at which the cumulative total reaches 16% is defined as the volume particle size D16v and the number particle size D16p, the particle size at which the cumulative total reaches 50% is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size at which the cumulative total reaches 84% ​​is defined as the volume particle size D84v and the number particle size D84p. Using these, the volume particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 The GSDp index is (D84p / D16p) 1 / 2 It is calculated as follows.

[0071] The average circularity of the toner particles is preferably 0.90 or more and 1.00 or less, and more preferably 0.92 or more and 0.98 or less.

[0072] The average circularity of toner particles is determined by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle projection image)]. Specifically, it is a value measured by the following method. First, the toner particles to be measured are collected by suction, a flattened flow is formed, and a strobe flash is instantaneously activated to capture a still image of the particles. This particle image is then analyzed using a flow-type particle image analyzer (Paasche analyzer PAS, manufactured by Hosokawa Micron Corporation). The number of samples used to determine the average circularity is 10,000. If the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0073] [External additives] Examples of external additives include inorganic particles. These inorganic particles include SiO2, TiO2, Al2O3, SrTiO3, CaTiO3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, and K2O·(TiO2). n Examples include Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4.

[0074] The surface of the inorganic particles used as an external additive should preferably be hydrophobic. Hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic agent. The hydrophobic agent is not particularly limited, but examples include silane-based coupling agents, silicone oil, titanate-based coupling agents, and aluminum-based coupling agents. These may be used individually or in combination of two or more. The amount of hydrophobic treatment agent is typically, for example, 1 to 10 parts by mass per 100 parts by mass of inorganic particles.

[0075] Examples of external additives include resin particles (such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), and cleaning lubricants (for example, metal salts of higher fatty acids represented by zinc stearate, and particles of higher alcohols).

[0076] The amount of external additive added is preferably 0.01% by mass or more and 10% by mass or less relative to the toner particles, and more preferably 0.01% by mass or more and 6.0% by mass or less.

[0077] [Method for manufacturing toner for electrostatic image development] The electrostatic image developing toner according to this embodiment is obtained by manufacturing toner particles and then adding an external additive to the toner particles.

[0078] Toner particles may be manufactured by either a dry process (e.g., kneading and grinding) or a wet process (e.g., agglomeration, suspension polymerization, dissolution and suspension). There are no particular restrictions on these methods, and known methods can be used. Among these, obtaining toner particles by agglomeration is preferable.

[0079] Specifically, for example, when manufacturing toner particles by an aggregation and coalescence method, for example, The process involves mixing a first resin particle dispersion containing first resin particles that will serve as a binder, a colorant dispersion containing a colorant, and a release agent particle dispersion containing release agent particles (hereinafter also referred to as "release agent particles"), and then agglomerating each particle and the colorant in the resulting dispersion to form first aggregated particles (first aggregated particle formation process). After obtaining a first aggregate particle dispersion in which the first aggregate particles are dispersed, a second resin particle, which will become a binder resin, is added to the first aggregate particle dispersion to aggregate the second resin particle on the surface of the first aggregate particles, thereby forming second aggregate particles (second aggregate particle formation step). The process involves heating the second aggregate particle dispersion, in which the second aggregate particles are dispersed, to fuse and combine the second aggregate particles and form toner particles (fusion and combination process), The toner particles are manufactured through this process. This aggregation and coalescence method is described as a method for producing toner particles containing a binder resin, a colorant, and a release agent; however, the colorant and release agent are components included in the toner particles as needed.

[0080] The details of each step are explained below.

[0081] -Each dispersion preparation process- First, prepare each dispersion used in the agglomeration method. Specifically, prepare a first resin particle dispersion containing first resin particles that will act as the binder, a colorant dispersion containing a colorant, a second resin particle dispersion containing second resin particles that will act as the binder, and a release agent particle dispersion containing release agent particles. In each dispersion preparation step, the first resin particles and the second resin particles will be referred to as "resin particles" in the explanation.

[0082] Here, the resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium with a surfactant.

[0083] Examples of dispersion media used in resin particle dispersions include aqueous media. Examples of aqueous media include water such as distilled water and deionized water, and alcohols. These may be used individually or in combination of two or more.

[0084] Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycol, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly noteworthy. Nonionic surfactants may be used in combination with anionic or cationic surfactants. Surfactants may be used individually or in combination of two or more types.

[0085] In resin particle dispersions, common dispersion methods for dispersing resin particles in a dispersion medium include, for example, rotary shear homogenizers, ball mills with media, sand mills, and dyno mills. Depending on the type of resin particles, the resin particles may also be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method. Phase inversion emulsification is a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase) to neutralize it, and then an aqueous medium (W phase) is added. This causes a conversion of the resin from W / O to O / W (so-called phase inversion), resulting in a discontinuous phase, and the resin is dispersed in the aqueous medium in particulate form.

[0086] The volume-average particle size of the resin particles dispersed in the resin particle dispersion is preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and even more preferably 0.1 μm or more and 0.6 μm or less. The volume-average particle size of the resin particles is measured using a laser diffraction particle size distribution analyzer (e.g., LA-960, manufactured by Horiba, Ltd.). The particle size distribution is obtained by subtracting the cumulative distribution from the smallest particle size side for each divided particle size range (channel), and the particle size that accounts for 50% of the total particle size is measured as the volume-average particle size D50v. The volume-average particle size of particles in other dispersions is measured in the same manner.

[0087] The resin particle content in the resin particle dispersion is preferably, for example, 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0088] In addition, colorant dispersions and mold release agent particle dispersions are prepared in the same manner as the resin particle dispersions. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the resin particle dispersions are the same for the colorant dispersed in the colorant dispersion and the mold release agent particles dispersed in the mold release agent particle dispersion.

[0089] -First agglomerated particle formation process- Next, the first resin particle dispersion, the colorant dispersion, and the mold release agent particle dispersion are mixed together. Then, in this mixed dispersion, the first resin particles, colorant, and release agent particles are heteroaggregated to form first aggregated particles containing the first resin particles, colorant, and release agent particles.

[0090] Specifically, for example, a flocculant is added to a dispersion obtained by mixing a first resin particle dispersion, a colorant dispersion, and a mold release agent particle dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, pH 2 to 5). After adding a dispersion stabilizer as needed, the temperature is set to a range of 20°C to 50°C to flocce the particles dispersed in the mixed dispersion and form first flocculated particles. In the first agglomerated particle formation step, for example, the mixed dispersion may be stirred with a rotary shear homogenizer, the above-mentioned flocculant may be added at room temperature (e.g., 25°C), the pH of the mixed dispersion may be adjusted to acidic (e.g., pH 2 to 5), a dispersion stabilizer may be added as needed, and then the above-mentioned heating may be performed.

[0091] Examples of flocculants include surfactants with opposite polarity to the surfactant used as a dispersant added to a mixed dispersion, inorganic metal salts, and metal complexes with a valency of 2 or higher. In particular, when a metal complex is used as a flocculant, the amount of surfactant used is reduced and the electrostatic properties are improved. Additives that form complexes or similar bonds with the metal ions of the flocculant may be used as needed. Chelating agents are preferably used as such additives.

[0092] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. As a chelating agent, a water-soluble chelating agent may be used. Examples of chelating agents include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, as well as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). The amount of chelating agent to be added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the first resin particles, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass. Additionally, alkali may be added to adjust the pH of the system in order to control the effect of the chelating agent.

[0093] -Second agglomerated particle formation process- Next, after obtaining a first aggregate particle dispersion containing the first aggregate particles, a second resin particle dispersion containing the second resin particles is added to the first aggregate particle dispersion. The second resin particles may be of the same type as the first resin particles, or they may be of a different type.

[0094] Then, in a dispersion of first aggregated particles and second resin particles, the second resin particles are aggregated on the surface of the first aggregated particles. At this time, a release agent particle dispersion may also be added to aggregate the second resin particles and release agent particles on the surface of the first aggregated particles. Specifically, for example, in the first aggregated particle formation step, when the first aggregated particles reach the desired particle size, the second resin particle dispersion is added to the first aggregated particle dispersion, and heating is performed at a temperature below the glass transition temperature of the second resin particles. Then, by adjusting the pH of the dispersion to a range of, for example, between 6.5 and 8.5, the progression of aggregation is stopped. In this way, a second aggregated particle is obtained by agglomerating the first aggregated particle so that the second resin particle adheres to its surface.

[0095] -Fusion / unification process- Next, the second aggregate particle dispersion, in which the second aggregate particles are dispersed, is heated to a temperature above the glass transition temperature of the first and second resin particles (for example, 10 to 30°C higher than the glass transition temperature of the first and second resin particles) to fuse and combine the second aggregate particles and form toner particles. Additionally, the pH of the system may be adjusted by adding acid as needed to control the shape.

[0096] Toner particles are obtained through the above process. Furthermore, in the agglomeration and coalescence method described above, the second agglomeration particle formation step may be omitted, and the first agglomeration particles may be fused and coalesced to form toner particles. Alternatively, the second agglomeration particle formation step may be repeated multiple times.

[0097] Here, after the fusion and combination process is completed, the toner particles in the dispersion are subjected to known washing, solid-liquid separation, and drying processes to obtain dried toner particles. The washing process should be thoroughly performed using ion-exchanged water for displacement washing, considering the electrostatic charge. The solid-liquid separation process is not particularly restricted, but suction filtration, pressure filtration, etc., are preferable for productivity. The drying process is also not particularly restricted, but freeze-drying, air-flow drying, fluidized bed drying, vibratory fluidized bed drying, etc., are preferable for productivity.

[0098] The toner according to this embodiment is manufactured, for example, by adding an external additive to the obtained dried toner particles and mixing them. Mixing can be performed using, for example, a V-blender, a Henschel mixer, a Redigge mixer, etc. The external additive may be mixed with the toner particles all at once, or the external additive may be added to the toner particles in stages and mixed multiple times. Furthermore, if necessary, coarse particles of toner may be removed using a vibrating screen separator, a wind screen separator, etc.

[0099] (Electrostatic image developer) The electrostatic image developer according to this embodiment includes at least the electrostatic image developing toner according to this embodiment. The electrostatic image developer according to this embodiment may be a one-component developer containing only the electrostatic image developing toner according to this embodiment, or it may be a two-component developer in which the electrostatic image developing toner and a carrier are mixed.

[0100] There are no particular restrictions on the carriers, and known carriers can be used. Examples of carriers include coated carriers in which a resin is coated on the surface of a core material made of magnetic powder; magnetic powder dispersed carriers in which magnetic powder is dispersed in a matrix resin; and resin-impregnated carriers in which resin is impregnated into porous magnetic powder. Magnetic powder dispersion carriers and resin-impregnated carriers may be carriers in which the constituent particles of the carrier are used as a core material and the surface thereof is coated with resin.

[0101] Examples of magnetic powders include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0102] In particular, magnetite and ferrite are preferred as magnetic powders. The magnetic powder may also be used as particles in which the magnetic powder is dispersed in a resin.

[0103] Examples of coating resins and matrix resins include styrene-(meth)acrylic acid resin; polyolefin resins such as polyethylene resin and polypropylene resin; polyvinyl or polyvinylidene resins such as polystyrene-(meth)acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylcarbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; straight silicone resins or modified products thereof consisting of organosiloxane bonds; fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate; amino resins such as urea-formaldehyde resin; epoxy resin; and the like. The coating resin and matrix resin preferably contain a (meth)acrylic resin, and more preferably contain a (meth)acrylic resin having an alicyclic structure. The coating resin and matrix resin may also contain a nitrogen-containing (meth)acrylic resin. It is more preferable that the (meth)acrylic resin is present in an amount of 50% by mass or more relative to the total mass of the resin, and even more preferable that the (meth)acrylic resin is present in an amount of 80% by mass or more relative to the total mass of the resin. In particular, the coating resin and the matrix resin preferably contain an alicyclic (meth)acrylic resin as the (meth)acrylic resin. The coating resin and matrix resin may contain conductive particles and other additives. Examples of conductive particles include metals such as gold, silver, and copper, as well as carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate. Other additives include metal oxide particles such as silica, titanium oxide, zinc oxide, and tin oxide; metal compound particles such as barium sulfate, aluminum borate, and potassium titanate; and metal particles such as gold, silver, and copper. Among these, silica particles are preferred. The above particles are preferably contained in an amount of 10% to 60% by mass relative to the total mass of the resin layer.

[0104] To coat the surface of the core material with resin, one method is to coat it with a coating layer-forming solution prepared by dissolving the coating resin and various additives (used as needed) in a suitable solvent. The solvent is not particularly limited and should be selected considering the type of resin used and its suitability for coating. Specific resin coating methods include the immersion method, in which the core material is immersed in a coating layer forming solution; the spray method, in which the coating layer forming solution is sprayed onto the surface of the core material; the fluidized bed method, in which the coating layer forming solution is sprayed onto the core material while it is suspended by fluidized air; and the kneader coater method, in which the carrier core material and the coating layer forming solution are mixed in a kneader coater, and then the solvent is removed.

[0105] In a two-component developer, the mixing ratio (mass ratio) of toner and carrier is preferably toner:carrier = 1:100 to 30:100, and more preferably 3:100 to 20:100.

[0106] (Image forming device, image forming method) The image forming apparatus and image forming method according to this embodiment will be described below. The image forming apparatus according to this embodiment comprises an image holder, a charging device for charging the surface of the image holder, an electrostatic image forming apparatus for forming an electrostatic image on the charged surface of the image holder, a developing apparatus for containing an electrostatic image developer and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, a transfer apparatus for transferring the toner image formed on the surface of the image holder to the surface of a recording medium, and a fixing apparatus for fixing the toner image transferred to the surface of the recording medium. The electrostatic image developer according to this embodiment is used as the electrostatic image developer.

[0107] The image forming apparatus according to this embodiment implements an image forming method (image forming method according to this embodiment) comprising: a charging step of charging the surface of an image holder; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image holder; a developing step of developing the electrostatic image formed on the surface of the image holder as a toner image using an electrostatic image developer according to this embodiment; a transfer step of transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0108] The image forming apparatus according to this embodiment may be a known image forming apparatus such as: a direct transfer apparatus that directly transfers a toner image formed on the surface of an image holder to a recording medium; an intermediate transfer apparatus that first transfers a toner image formed on the surface of an intermediate transfer body to the surface of an intermediate transfer body, and secondly transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; an apparatus equipped with a cleaning device that cleans the surface of the image holder after the transfer of the toner image and before charging, or an apparatus equipped with a static elimination device that irradiates the surface of the image holder with static elimination light to eliminate static charge after the transfer of the toner image and before charging; etc. In the case of an intermediate transfer method apparatus, the transfer apparatus may include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer apparatus that first transfers the toner image formed on the surface of the image holder to the surface of the intermediate transfer body; and a secondary transfer apparatus that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0109] In the image forming apparatus according to this embodiment, for example, the part including the developing device may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with a developing device that contains the electrostatic image developer according to this embodiment is preferably used.

[0110] The following is an example of an image forming apparatus according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will be omitted from the explanation.

[0111] Figure 1 is a schematic diagram showing the image forming apparatus according to this embodiment. The image forming apparatus shown in Figure 1 is equipped with first to fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K that output images of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side at predetermined distances from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may also be process cartridges that can be attached to and detached from the image forming apparatus.

[0112] In the drawings of each unit 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 is extended through each unit as an intermediate transfer body. The intermediate transfer belt 20 is wound around drive rolls 22 and support rolls 24 that are spaced apart from each other from left to right in the drawing and are in contact with the inner surface of the intermediate transfer belt 20, and is configured to travel in the direction from the first unit 10Y to the fourth unit 10K. The support rolls 24 are subjected to a force that moves away from the drive rolls 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around both. An intermediate transfer body cleaning device 30 is provided on the outer surface of the intermediate transfer belt 20, facing the drive rolls 22. Furthermore, each of the developing units (examples of developing units) 4Y, 4M, 4C, and 4K for each unit 10Y, 10M, 10C, and 10K is supplied with toner containing four colors of toner: yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K.

[0113] Since the first to fourth units 10Y, 10M, 10C, and 10K have equivalent configurations, the first unit 10Y, which forms the yellow image and is located on the upstream side in the direction of travel of the intermediate transfer belt, will be described as a representative example. The descriptions of the second to fourth units 10M, 10C, and 10K will be omitted by assigning reference numerals to parts equivalent to the first unit 10Y, with magenta (M), cyan (C), and black (K) instead of yellow (Y).

[0114] The first unit 10Y has a photoreceptor 1Y that acts as an image holder. Around the photoreceptor 1Y are a charging roll (an example of a charging device) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, an exposure device (an example of an electrostatic image forming device) 3 that exposes the charged surface with a laser beam 3Y based on a color-separated image signal to form an electrostatic image, a developing device (an example of a developing device) 4Y that supplies charged toner to the electrostatic image to develop the electrostatic image, a primary transfer roll 5Y (an example of a primary transfer device) that transfers the developed toner image onto an intermediate transfer belt 20, and a photoreceptor cleaning device that removes toner remaining on the surface of the photoreceptor 1Y after primary transfer. (Example of a cleaning device) 6Y are arranged in order. The primary transfer roll 5Y is positioned inside the intermediate transfer belt 20, facing the photoreceptor 1Y. Furthermore, each of the primary transfer rolls 5Y, 5M, 5C, and 5K is connected to a bias power supply (not shown) that applies a primary transfer bias. Each bias power supply varies the transfer bias applied to each primary transfer roll through control by a control unit (not shown).

[0115] The following describes the process of forming the yellow image in the first unit 10Y. First, prior to operation, the surface of the photoreceptor 1Y is charged to a potential of -600V to -800V by the charging roll 2Y. The photoreceptor 1Y is conductive (e.g., volume resistivity at 20°C: 1 × 10⁻⁶). -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate (less than Ωcm). This photosensitive layer normally has high resistance (resistance of general resin), but when irradiated with a laser beam 3Y, the resistivity of the irradiated area changes. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 according to image data for yellow sent from a control unit (not shown). The laser beam 3Y irradiates the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic image of the yellow image pattern on the surface of the photoreceptor 1Y.

[0116] A static charge image is an image formed on the surface of a photoreceptor 1Y due to charging. It is a so-called negative latent image formed when the resistivity of the irradiated portion of the photoreceptor layer decreases due to the laser beam 3Y, causing the charged material on the surface of the photoreceptor 1Y to flow, while the charge remains in the portion not irradiated by the laser beam 3Y. The electrostatic charge image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y moves. At this development position, the electrostatic charge image on the photoreceptor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0117] The developing device 4Y contains, for example, an electrostatic image developer including at least yellow toner and a carrier. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y and is held on the developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the static charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image on the surface of the photoreceptor 1Y, and the latent image is developed by the yellow toner. The photoreceptor 1Y, on which the yellow toner image has been formed, continues to move at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0118] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y acts on the toner image, transferring the toner image on the photoreceptor 1Y onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity opposite to the toner's polarity (-) (+), and for example, in the first unit 10Y, it is controlled to +10 μA by a control unit (not shown). Meanwhile, any toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0119] Furthermore, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K of the second unit from 10M onward is also controlled in accordance with the first unit. Thus, the intermediate transfer belt 20, on which the yellow toner image has been transferred in the first unit 10Y, is sequentially transported through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed and transferred in multiple layers.

[0120] Intermediate transfer belt 2 through which four-color toner images are multi-transferred via units 1 to 4. The process leads to a secondary transfer section, which consists of an intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer device) 26 positioned on the outer circumferential surface of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is fed via a supply mechanism into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 at a predetermined timing, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has the same polarity (-) as the toner's polarity (-), and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection device (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0121] After this, the recording paper P is fed to the contact area (nip area) of a pair of fixing rolls in a fixing device (an example of a fixing device) 28, where the toner image is fixed onto the recording paper P, and a fixed image is formed.

[0122] Examples of recording paper P used to transfer toner images include plain paper used in electrophotographic photocopiers and printers. Other recording media besides recording paper P include OHP sheets. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper, which is plain paper coated with resin or the like, or art paper for printing are suitable for use.

[0123] Once the color image has been fixed onto the recording paper P, it is discharged towards the output section, and the series of color image formation operations is completed.

[0124] <Processor Cartridges / Toner Cartridges> The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment contains the electrostatic image developer according to this embodiment, and is equipped with a developing device that develops the electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer, and is a process cartridge that can be attached to and detached from an image forming apparatus.

[0125] The process cartridge according to this embodiment is not limited to the above configuration, and may also include a developing device and, as necessary, at least one other device selected from, for example, an image holder, a charging device, an electrostatic image forming device, and a transfer device.

[0126] The following shows an example of a process cartridge according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will not be explained.

[0127] Figure 2 is a schematic diagram showing the process cartridge according to this embodiment. The process cartridge 200 shown in Figure 2 is constructed by integrally holding a photoreceptor 107 (an example of an image holder), a charging roll 108 (an example of a charging device), a developing device 111 (an example of a developing device), and a photoreceptor cleaning device 113 (an example of a cleaning device) provided around the photoreceptor 107, using a housing 117 equipped with a mounting rail 116 and an opening 118 for exposure, and is then formed into a cartridge. In Figure 2, 109 represents an exposure apparatus (an example of an electrostatic image forming apparatus), 112 represents a transfer apparatus (an example of a transfer apparatus), 115 represents a fixing apparatus (an example of a fixing apparatus), and 300 represents recording paper (an example of a recording medium).

[0128] Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to this embodiment contains the toner according to this embodiment and forms an image. This is a toner cartridge that is attached to and detached from the device. The toner cartridge contains replenishment toner for supply to the developing device located within the image forming apparatus.

[0129] The image forming apparatus shown in Figure 1 is an image forming apparatus with removable toner cartridges 8Y, 8M, 8C, and 8K. The developing units 4Y, 4M, 4C, and 4K are connected to toner cartridges corresponding to each developing unit (color) by toner supply pipes (not shown). When the toner contained in a toner cartridge becomes low, the toner cartridge is replaced. [Examples]

[0130] The embodiments of the invention will be described in detail below with reference to examples, but the embodiments of the invention are not limited to these examples. In the following explanation, unless otherwise specified, "parts" and "%" refer to mass. Synthesis, processing, and manufacturing were carried out at room temperature (25°C ± 3°C) unless otherwise specified.

[0131] (Example 1) <Preparation of Styrene-(meth)acrylate copolymer particle dispersion (1) for forming spherical domain A> • Styrene: 50 units n-butyl acrylate (BA): 50 parts · 1,10-Decanediol diacrylate (DDDA): 1.0 part • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.) 1.2 parts • Ion-exchanged water: 86 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsified solution. In a reaction vessel equipped with a stirring device and a nitrogen inlet tube, the inside of the vessel was purged with nitrogen, and then 0.3 parts of anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.) and 100 parts of deionized water were added. The reaction solution was heated in an oil bath while stirring, and the temperature of the reaction solution was raised to 75°C. After adding 3 parts of the emulsifier, 20 parts of an aqueous solution of ammonium persulfate, adjusted to a concentration of 10% by mass, were added and the mixture was held for 30 minutes. Subsequently, while maintaining the reaction solution temperature at 75°C, the emulsion was gradually added dropwise to the reaction vessel using a pump over 200 minutes. After the dropwise addition was complete, the mixture was held for 60 minutes, then 2 parts of 10% by mass ammonium persulfate were added, and the mixture was held for a further 3 hours before being cooled to room temperature. The resulting dispersion of resin fine particles was sieved through a 70 μm mesh sieve to remove aggregates formed during the polymerization process, and obtained the styrene-(meth)acrylate copolymer particle dispersion (1) for forming spherical domain A.

[0132] <Preparation of Styrene-(meth)acrylate copolymer particle dispersion (2) for forming spherical domain B> • Styrene: 76 units n-butyl acrylate: 24 parts · 1,10-decanediol diacrylate: 0.1 part Dodecanethiol: 0.7 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.) 1.2 parts • Ion-exchanged water: 86 parts A styrene-(meth)acrylate copolymer particle dispersion (2) for forming spherical domain B was obtained by the same procedure as for styrene-(meth)acrylate copolymer particle dispersion (1), except that the raw material composition was changed as described above.

[0133] <Preparation of amorphous resin particle dispersion 1> Terephthalic acid: 98 molar parts • Fumatrimethic anhydride: 2 moles • Bisphenol A ethylene oxide 2 molar adduct: 20 moles • Bisphenol A propylene oxide 2 molar adduct: 80 molar parts The above materials were placed in a reaction vessel equipped with a stirrer, nitrogen inlet tube, temperature sensor, and rectification column. The temperature was raised to 190°C over 1 hour, and 1.2 parts of dibutyltin oxide were added for every 100 parts of the above materials. The temperature was raised to 240°C over 6 hours while distilling off the generated water, and the dehydration condensation reaction was continued at 240°C for 3 hours, after which the reactants were cooled. The reactants were transferred in a molten state to a Cavitron CD1010 (manufactured by Eurotech) at a rate of 100 g per minute. Simultaneously, a separately prepared 0.37 mass% ammonia solution was transferred to the Cavitron CD1010 at a rate of 0.1 liters per minute while being heated to 120°C in a heat exchanger. The rotor speed was 60 Hz and the pressure was 5 kg / cm². 2 The Cavitron CD1010 was operated under the specified conditions to obtain a resin particle dispersion containing resin particles with a volume-average particle size of 150 nm. Ion-exchanged water was added to the resin particle dispersion to adjust the solid content to 20% by mass, resulting in amorphous resin particle dispersion 1.

[0134] <Preparation of crystalline resin particle dispersion 1> • 1,10-Dodecanedioic acid: 225 parts by mass • 1,10-Dodecanediol: 174 parts by mass The above materials were placed in a reaction vessel equipped with a stirrer, nitrogen inlet tube, temperature sensor, and rectification column. The temperature was raised to 160°C over 1 hour, and 0.8 parts by mass of dibutyltin oxide were added. The temperature was raised to 180°C over 6 hours while distilling off the generated water, and the dehydration condensation reaction was continued at 180°C for 5 hours. After that, the temperature was gradually raised to 230°C under reduced pressure, and the mixture was stirred at 230°C for 2 hours. The reaction mixture was then cooled. After cooling, solid-liquid separation was performed, and the solid was dried to obtain a crystalline polyester resin.

[0135] Crystalline polyester resin: 100 parts • Methyl ethyl ketone: 40 parts Isopropyl alcohol: 30 parts 10% ammonia aqueous solution: 6 parts The above materials were added to a jacketed reaction vessel (manufactured by Tokyo Rikakikai Co., Ltd.: BJ-30N) equipped with a condenser, thermometer, water dropper, and anchor vanes. The resin was dissolved while stirring at 100 rpm in a water-circulating constant temperature bath while maintaining a temperature of 80°C. Subsequently, the water-circulating constant temperature bath was set to 50°C, and 400 parts of ion-exchanged water, kept at 50°C, were added dropwise at a rate of 7 parts by mass / min to invert the phase and obtain an emulsion. 576 parts by mass of the obtained emulsion and 500 parts by mass of ion-exchanged water were placed in a round-bottom flask and set in an evaporator (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. The round-bottom flask was heated in a 60°C water bath while rotating, and the pressure was reduced to 7 kPa while taking care to prevent bumping to remove the solvent. After that, ion-exchanged water was added to obtain a crystalline resin particle dispersion 1 with a solid content concentration of 20% by mass.

[0136] <Preparation of colorant dispersion> • Carbon black (Cabot Regal 330): 50 units • Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 5 parts • Ion-exchanged water: 192.9 parts The above components were mixed and treated with an ultimateizer (manufactured by Sugino Machine Co., Ltd.) at 240 MPa for 10 minutes to prepare a colorant dispersion (solid content: 20%).

[0137] <Preparation of mold release agent dispersion> Fischer-Tropsch wax (FNP0090, manufactured by Nippon Seiro Co., Ltd., melting point Tw: 90℃): 50 parts • Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part • Ion-exchanged water: 200 bottles The above materials were mixed and heated to 130°C, dispersed using a homogenizer (IKA Ultra-Turrax T50), and then dispersed again using a Manton-Gorin high-pressure homogenizer (Gorin), to obtain a release agent dispersion (solid content 20% by mass) in which release agent particles were dispersed.

[0138] <Preparation of toner particles 1> ·Amorphous resin particle dispersion 1:170 parts ·Crystalline resin particle dispersion 1:16 parts • Styrene-(meth)acrylate copolymer particle dispersion (1): 31 parts • Styrene-(meth)acrylate copolymer particle dispersion (2): 24 parts • Colorant dispersion: 40 parts • Release agent dispersion: 25 parts • Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part • Ion-exchanged water: 250 units The above materials were placed in a reaction vessel equipped with a thermometer, pH meter, and stirrer, and heated externally to 30°C using a mantle heater. The mixture was then stirred at 150 rpm for 30 minutes. Next, a 0.3N (=0.3 mol / L) aqueous nitric acid solution was added to adjust the pH to 3.0. Then, a 3% by mass aqueous solution of polyaluminum chloride was added while dispersing in a homogenizer (IKA Ultra-Turrax T50). Next, the temperature was raised to 50°C while stirring and held for 30 minutes. Then, 149 parts of amorphous resin particle dispersion were added and held for 1 hour. After adding a 0.1N (=0.1 mol / L) aqueous sodium hydroxide solution to adjust the pH to 8.5, the mixture was heated to 90°C while continuing to stir and held for 5 hours. Finally, cooling, solid-liquid separation, washing of solids, and drying were carried out sequentially to obtain toner particles 1 with a volume-average particle size of 6.0 μm.

[0139] <Preparation of Toner 1> Toner 1 was obtained by mixing 100 parts of toner particles 1 and 2.0 parts of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., product name: RY200) in a Henschel mixer.

[0140] (Examples 2-30 and Comparative Examples 1-6) The toners were prepared in the same manner as in Example 1, except that the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1) for forming spherical domain A, the styrene-(meth)acrylate copolymer particle dispersion (2) for forming spherical domain B, the amorphous resin particle dispersion 1, and the preparation of the toner particles 1 were modified as shown in Table 1 or Table 2.

[0141] (Comparative Example 7) <Preparation of Seed Polymerization Particle Dispersion> -Preparation of Emulsified Solution 1- Styrene: 27.8 parts n-butyl acrylate (BA): 27.8 parts · 1,10-decanediol diacrylate (DDDA): 0.6 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.) 0.7 parts • Ion-exchanged water: 47.8 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare emulsified liquid 1.

[0142] -Preparation of Emulsified Solution 2- • Styrene: 33.8 parts n-butyl acrylate (BA): 10.7 parts · 1,10-Decanediol diacrylate (DDDA): 0.1 part Dodecanethiol: 0.3 parts • Anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.) 0.5 parts • Ion-exchanged water: 38.2 parts The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare emulsion solution 2.

[0143] In a reaction vessel equipped with a stirring device and a nitrogen inlet tube, the inside of the vessel was purged with nitrogen, and then 0.3 parts of anionic surfactant (Eleminol MON-2, manufactured by Sanyo Chemical Industries, Ltd.) and 100 parts of deionized water were added. The reaction solution was heated in an oil bath while stirring, and the temperature of the reaction solution was raised to 75°C. After adding 3 parts of emulsifier 1, 20 parts of an aqueous solution of ammonium persulfate, adjusted to a concentration of 10% by mass, were added and the mixture was held for 30 minutes. Subsequently, while maintaining the reaction solution temperature at 75°C, emulsion 1 was gradually added dropwise to the reaction vessel using a pump over 111 minutes. After the addition was complete, it was held for 15 minutes, and then emulsion 2 was gradually added dropwise using a pump over 89 minutes. After holding for 60 minutes, 2 parts of 10% by mass ammonium persulfate were added, and after holding for a further 3 hours, it was cooled to room temperature. The resulting dispersion of resin fine particles was sieved through a 70 μm mesh sieve to remove aggregates formed during the polymerization process, and the resulting seed polymerization particle dispersion was obtained.

[0144] <Method for measuring Tg1 of spherical domain A in styrene (meth)acrylic resin> The tetrahydrofuran (THF) insoluble content of toner particles was measured using differential thermal analysis (DSC), and Tg1 was determined.

[0145] <Method for measuring Tg2 of spherical domain B in styrene (meth)acrylic resin> The monomer composition ratio was calculated by nuclear magnetic resonance (NMR) measurements of toner particles, and Tg2 was calculated using the FOX formula.

[0146] <Method for measuring domain diameter> The sizes of low-Tg domains and high-Tg domains were measured in the cross-section of toner particles using atomic force microscopy-infrared spectroscopy (AFM-IR), and the average values ​​were calculated.

[0147] <Evaluation of low-temperature fixation ability> The obtained toner was processed using a DocuCentreColor400 manufactured by Fujifilm Business Innovation Co., Ltd., with a toner load of 13.5 g / m². 2The unfixed image was output after adjustments were made to achieve the desired result. Film-based synthetic paper (Yupo paper, manufactured by Yupo Corporation) was used as the recording medium. The output image was a 25mm x 25mm solid image with 100% image density. For the fixation evaluation device, a modified ApeosPortIV C3370 manufactured by Fujifilm Business Innovation Co., Ltd. was used, with the fuser removed and the fixing temperature adjustable. The nip width of the fixation evaluation device was 6mm, and the nip thickness was 1.6kgf / cm². 2 The process speed was 175 mm / sec. Unfixed images were fixed at fixing temperatures ranging from 90°C to 180°C in 5°C increments. A good fixed image, free from image loss and distortion due to peeling failure, was folded and a 50g load was applied. The degree of image loss in that area was observed, and the fixing temperature at which some peeling of the image was observed but deemed to be at a level that did not pose a practical problem was evaluated as the minimum fixing temperature.

[0148] <Evaluation of shade suppression> The toner obtained was filled into a toner cartridge and installed in an image forming machine (a modified ApeosPort-IV C5575 manufactured by Fujifilm Business Innovation Co., Ltd.). The developer for each example was then filled into the developing unit of this image forming machine. Under conditions of 30°C and 85% relative humidity, 10,000 images with an image density of 5% were printed on A4-sized paper and left for 24 hours. After 24 hours, 10 images with an image density of 5% were printed on A4-sized paper. The degree of haze was evaluated by observing the 10 images with the naked eye and with a 5x magnification loupe. The evaluation criteria are as follows. A: No haze was observed during magnification examination. B: When examined with a magnifying glass, 1 to 4 layers of image overlap were observed, but this does not affect practical use. C: When inspected with a magnifying glass, five or more lenses showed some blurring, but this does not affect practical use. D: Both with a magnifying glass and with the naked eye, haze was observed in 5 or more images, making them unsuitable for practical use.

[0149] [Table 1]

[0150] [Table 2]

[0151] The abbreviations listed in Table 2, other than those mentioned above, are shown below. 2EHA:2-Ethylhexylacrylate

[0152] As shown in Tables 1 and 2, the electrostatic image developing toner of the example was superior to the electrostatic image developing toner of the comparative example in both fogging suppression and low-temperature fixing properties.

[0153] (((1))) A toner for developing electrostatic images, comprising toner particles containing an amorphous polyester resin and a styrene (meth)acrylic resin, wherein the toner particles have a spherical domain A of styrene (meth)acrylic resin that is insoluble in tetrahydrofuran and a spherical domain B of styrene (meth)acrylic resin that is soluble in tetrahydrofuran, the glass transition temperature Tg1 of the spherical domain A of styrene (meth)acrylic resin is 0°C or more and 35°C or less, and when the glass transition temperature of the spherical domain B of styrene (meth)acrylic resin is Tg2, the value of Tg2-Tg1 is 20°C or more and 55°C or less. (((2))) The electrostatic image developing toner according to (((1))) in which the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is W1 by mass, and the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin is W2 by mass, satisfying 0.3 ≤ W1 / W2 ≤ 3.0. (((3))) The electrostatic image developing toner according to (((1))) or (((2))) in which the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is W1 by mass, and the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin is W2 by mass, such that 5 ≤ W1 + W2 ≤ 40. (((4))) The toner for developing electrostatic images according to any one of (((1))) to (((3))), wherein the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is 1.5% by mass or more and 30% by mass or less. (((5))) The toner for developing electrostatic images according to any one of (((1))) to (((4))), wherein the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin in the toner particles is 1.5% by mass or more and 25% by mass or less. (((6))) The toner for developing electrostatic images according to any one of (((1))) to (((5))), wherein the domain diameter of the spherical domain A of the styrene (meth)acrylic resin is 50 nm or more and 300 nm or less. (((7))) The toner for developing electrostatic images according to any one of (((1))) to (((6))), wherein the domain diameter of the spherical domain B of the styrene (meth)acrylic resin is 300 nm or more and 800 nm or less. (((8))) The toner for developing electrostatic images according to any one of (((1))) to (((7))) in which the domain diameter of spherical domain A of the styrene (meth)acrylic resin is smaller than the domain diameter of spherical domain B of the styrene (meth)acrylic resin. (((9))) The toner for developing electrostatic images according to any one of (((1))) to (((8))), wherein the acid value of the amorphous polyester resin is 6 mg KOH / g or more and 16 mg KOH / g or less. A electrostatic image developer containing a toner for developing electrostatic images as described in any one of (((10))) (((1))) to (((9))). A toner cartridge that contains the electrostatic image developing toner described in any one of (((11))) (((1))) to (((9))) and is attached to and detached from an image forming apparatus. A process cartridge that is attached to and detached from an image forming apparatus, comprising a developing device that contains the electrostatic image developer described in (((12))) (((10))) and develops an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer. (((13))) An image forming apparatus comprising: an image holder; a charging device for charging the surface of the image holder; an electrostatic image forming device for forming an electrostatic image on the charged surface of the image holder; a developing device for containing the electrostatic image developer described in (((10))) and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer; a transfer device for transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing device for fixing the toner image transferred to the surface of the recording medium. (((14))) An image forming method comprising: a charging step of charging the surface of an image holder; a static charge image forming step of forming a static charge image on the charged surface of the image holder; a developing step of developing the static charge image formed on the surface of the image holder as a toner image using the static charge image developer described in (((10))); a transfer step of transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0154] According to the invention of (((1))), a toner for electrostatic image development is provided in which the toner particles have spherical domains A of styrene(meth)acrylic resin that are insoluble in tetrahydrofuran and spherical domains B of styrene(meth)acrylic resin that are soluble in tetrahydrofuran, and the Tg1 of the spherical domains A of styrene(meth)acrylic resin is less than 0°C or greater than 35°C, or the value of Tg2-Tg1 is less than 20°C or greater than 55°C when the glass transition temperature of the spherical domains B of styrene(meth)acrylic resin is Tg2, and the fogging suppression and low-temperature fixing properties are superior to those of the case described above. According to the invention of (((2))), a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the value of W1 / W2 is less than 0.3 or greater than 3.0. According to the invention of (((3))), a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the value of W1 + W2 is less than 5 or greater than 40. According to the invention of (((4))), a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is less than 1.5% by mass or more than 30% by mass. According to the invention of (((5))), a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin in the toner particles is less than 1.5% by mass or more than 25% by mass. According to the invention of (((6))), a toner for electrostatic image development is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the domain diameter of the spherical domain A of the styrene (meth)acrylic resin is less than 50 nm or greater than 300 nm. According to the invention of (((7))), a toner for developing electrostatic images is provided that is superior in fogging suppression and low-temperature fixing performance compared to cases where the domain diameter of the spherical domain B of the styrene (meth)acrylic resin is less than 300 nm or greater than 800 nm. According to the invention of (((8))), a toner for developing electrostatic images is provided that is superior in fogging suppression and low-temperature fixing performance compared to the case in which the domain diameter of the spherical domain A of the styrene (meth)acrylic resin is equal to or greater than the domain diameter of the styrene (meth)acrylic resin B. According to the invention of (((9))), a toner for developing electrostatic images is provided that is superior in fogging suppression and low-temperature fixing properties compared to cases where the acid value of the amorphous polyester resin is less than 6 mg KOH / g or greater than 16 mg KOH / g. According to the inventions of (((10))), (((11))), (((12))), (((13))), or (((14))), the toner particles have spherical domains A of styrene(meth)acrylic resin that are insoluble in tetrahydrofuran and spherical domains B of styrene(meth)acrylic resin that are soluble in tetrahydrofuran, and the glass transition temperature Tg1 of the spherical domains A of styrene(meth)acrylic resin is less than 0°C or greater than 35°C, or when the glass transition temperature Tg2 of the spherical domains B of styrene(meth)acrylic resin is Tg2, the value of Tg2-Tg1 is less than 20°C or greater than 55°C. Compared to using an electrostatic image developing toner, an electrostatic image developing agent, toner cartridge, process cartridge, image forming apparatus, or image forming method is provided that exhibits superior fogging suppression and low-temperature fixing properties. [Explanation of Symbols]

[0155] 1Y, 1M, 1C, 1K photoreceptors (examples of image retainers) 2Y, 2M, 2C, 2K Charging Rolls (Example of a Charging Device) 3. Exposure apparatus (an example of an electrostatic imaging apparatus) 3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing equipment (an example of a developing equipment) 5Y, 5M, 5C, 5K Primary Transfer Rolls (Example of a Primary Transfer Device) 6Y, 6M, 6C, 6K Photoconductor Cleaning Device (Example of a 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 material) 22 Drive Roll 24 Support Rolls 26. Secondary transfer roll (an example of a secondary transfer device) 28 Fixing device (an example of a fixing device) 30 Intermediate Transfer Body Cleaning Apparatus 107 Photoreceptor (an example of an image-retaining element) 108 Charging Roll (Example of a Charging Device) 109 Exposure apparatus (an example of an electrostatic image forming apparatus) 111 Developing equipment (an example of a developing equipment) 112 Transfer device (an example of a transfer device) 113 Photoconductor Cleaning Device (An example of a cleaning device) 115 Fixing device (an example of a fixing device) 116 Mounting Rail 118 Aperture for exposure 117 cabinets 200 Process Cartridges 300 Recording paper (an example of a recording medium) P Recording paper (an example of a recording medium)

Claims

1. The toner particles contain amorphous polyester resin and styrene (meth)acrylic resin. The toner particles have a spherical domain A of styrene(meth)acrylic resin that is insoluble in tetrahydrofuran, and a spherical domain B of styrene(meth)acrylic resin that is soluble in tetrahydrofuran. The glass transition temperature Tg1 of the spherical domain A of the styrene (meth)acrylic resin is 0°C or higher and 35°C or lower. When the glass transition temperature of the spherical domain B of the styrene (meth)acrylic resin is denoted as Tg2, the value of Tg2 - Tg1 is between 20°C and 55°C. Toner for developing electrostatic images.

2. The toner for developing electrostatic images according to claim 1, wherein when the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is W1 by mass, and the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin is W2 by mass, the following condition is met: 0.3 ≤ W1 / W2 ≤ 3.

0.

3. The toner for developing electrostatic images according to claim 1, wherein when the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is W1 by mass, and the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin is W2 by mass, the toner satisfies 5 ≤ ​​W1 + W2 ≤ 40.

4. The toner for developing electrostatic images according to claim 1, wherein the content of styrene (meth)acrylic resin constituting the spherical domain A of the styrene (meth)acrylic resin in the toner particles is 1.5% by mass or more and 30% by mass or less.

5. The toner for developing electrostatic images according to claim 1, wherein the content of styrene (meth)acrylic resin constituting the spherical domain B of the styrene (meth)acrylic resin in the toner particles is 1.5% by mass or more and 25% by mass or less.

6. The electrostatic image developing toner according to claim 1, wherein the domain diameter of the spherical domain A of the styrene (meth)acrylic resin is 50 nm or more and 300 nm or less.

7. The electrostatic image developing toner according to claim 1, wherein the domain diameter of the spherical domain B of the styrene (meth)acrylic resin is 300 nm or more and 800 nm or less.

8. The electrostatic image developing toner according to claim 1, wherein the domain diameter of the spherical domain A of the styrene (meth)acrylic resin is smaller than the domain diameter of the styrene (meth)acrylic resin B.

9. The toner for developing electrostatic images according to claim 1, wherein the acid value of the amorphous polyester resin is 6 mg KOH / g or more and 16 mg KOH / g or less.

10. A electrostatic image developer comprising the electrostatic image developing toner according to any one of claims 1 to 9.

11. A toner cartridge containing the electrostatic image developing toner described in any one of claims 1 to 9, which is attached to and detached from an image forming apparatus.

12. A process cartridge that is attached to and detached from an image forming apparatus, comprising a developing apparatus that contains the electrostatic image developer described in claim 10 and develops an electrostatic image formed on the surface of an image holder as a toner image using the electrostatic image developer.

13. Image holder and, A charging device for charging the surface of the image holder, A static charge image forming apparatus for forming a static charge image on the surface of the charged image holder, A developing apparatus comprising: containing the electrostatic image developer described in claim 10; and developing an electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer; A transfer device for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, The recording medium comprises a fixing device for fixing the toner image transferred to its surface. Image forming apparatus.

14. A charging step in which the surface of the image holder is charged, A step of forming an electrostatic image on the surface of the charged image holder, A developing step of developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer described in claim 10, A transfer step of transferring the toner image formed on the surface of the image holder to the surface of the recording medium, The process includes fixing the toner image transferred to the surface of the recording medium. Image forming method.

Images