Toner, toner cartridge and image forming apparatus

Abstract

To provide a toner that has good adhesion to a print medium such as PET coating paper and is excellent in low temperature fixability and storage stability.SOLUTION: A toner has a core-shell structure. The core and the shell each contain a binder resin. The binder resin in the core includes a styrene-acrylic resin. The binder resin in the shell includes an amorphous polyester resin. When the binder resin in the shell is measured by a rheometer, the binder resin has a storage modulus at 70°C (G'(70°C)) of 500000 Pa or more and a storage modulus at 100°C (G'(100°C)) of 5000 Pa or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a toner that has excellent adhesion to a print medium, low-temperature fixability, and storage stability, and to a toner cartridge and an image forming apparatus that contain this toner. [Background technology]

[0002] Electrostatic image developing toners are used in image forming devices such as printers, copiers, and facsimiles to visualize electrostatic images. For example, in electrophotographic image formation, an electrostatic latent image is first formed on a photosensitive drum. This electrostatic latent image is then developed with toner, and transferred to a printing medium such as transfer paper. The toner is then heated and fixed to form an image.

[0003] Toner for developing electrostatic images generally has a structure in which solid fine particles such as silica are attached as an external additive to the surface of toner base particles containing a binder resin, a colorant, a wax, etc. Styrene acrylic resin is usually used as the binder resin for the toner base particles.

[0004] Such toners are required to have excellent adhesion to printing media such as paper. In particular, in recent years, PET-coated paper has become increasingly popular as a printing medium for the purpose of improving the variety, design, luxury, and durability of printed matter, and therefore, toners are required to have excellent adhesion to PET-coated paper.

[0005] Furthermore, when forming an image on a print medium, the toner is heated to fix it, but since the electricity required for this heating accounts for the majority of the power consumption of image forming devices such as copiers, toner is required to have the ability to fix at lower temperatures (low-temperature fixability).

[0006] Conventionally, as a toner excellent in low-temperature fixing property, heat-resistant storage property, etc., a toner for developing electrostatic images having a core-shell structure in which a shell is provided on the surface of a core particle has been proposed, in which the core particle contains a styrene acrylic resin and a release agent, and the shell contains a styrene acrylic modified polyester resin, the styrene acrylic resin of the core particle having a glass transition point of 35°C or more and 55°C or less and a weight average molecular weight of 20,000 or more and 40,000 or less, and the styrene acrylic modified polyester resin of the shell having a glass transition point of 50°C or more and 70°C or less and a weight average molecular weight of 7,000 or more and 19,000 or less (Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-247659 Summary of the Invention [Problem to be solved by the invention]

[0008] Conventional toners using styrene-acrylic resins as binder resins have insufficient low-temperature fixability. To improve low-temperature fixability, it is necessary to lower the viscosity of the toner, but lowering the viscosity of the toner leads to poor storage stability. To solve this problem, there is a toner with a core-shell structure as described in Patent Document 1, but there is a trade-off between low-temperature fixability and storage stability for each viscosity, making it difficult to achieve both low-temperature fixability and storage stability. The present invention aims to solve the above-mentioned problems of the conventional technology and to provide a toner that has good adhesion to printing media such as PET-coated paper and is also excellent in low-temperature fixability and storage stability, as well as a toner cartridge and image forming device that contain this toner. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that the above-mentioned problems can be solved by using a styrene acrylic resin as the binder resin for the core and an amorphous polyester resin as the binder resin for the shell in a toner having a core-shell structure, and by using a binder resin for the shell that has a predetermined low viscosity, specifically, a storage modulus at 70°C (G'(70°C)) that is a predetermined value or more and a storage modulus at 100°C (G'(100°C)) that is a predetermined value or less. That is, the present invention is summarized as follows.

[0010] [1] A toner having a core-shell structure, the core and the shell each contain a binder resin, the binder resin of the core contains a styrene acrylic resin, the binder resin of the shell contains an amorphous polyester resin, The toner has a storage modulus at 70°C (G'(70°C)) of 500,000 Pa or more and a storage modulus at 100°C (G'(100°C)) of 5,000 Pa or less when the binder resin of the shell is measured with a rheometer.

[0011] [2] The toner according to [1], wherein the binder resin of the core is a styrene acrylic resin, and the binder resin of the shell is an amorphous polyester resin.

[0012] [3] The toner according to [1] or [2], wherein the content of the amorphous polyester resin is 3% by mass or more and 40% by mass or less with respect to the total mass of the toner.

[0013] [4] The toner according to any one of [1] to [3], wherein the toner contains a wax, and the content of the wax in the toner is 5% by mass or more and 30% by mass or less.

[0014] [5] A toner cartridge containing the toner according to any one of [1] to [4].

[0015] [6] An image forming apparatus containing the toner according to any one of [1] to [4]. [Effects of the Invention]

[0016] According to the present invention, there are provided a toner that has good adhesion to print media such as PET-coated paper and also has excellent low-temperature fixability and storage stability, as well as a toner cartridge and an image-forming device that contain this toner. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following describes in detail the mode for carrying out the present invention (hereinafter referred to as "embodiments of the invention"). Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention.

[0018] In this specification, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more and Y or less," as well as "preferably larger than X" or "preferably smaller than Y." Furthermore, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also includes the intention that "it is preferable that it is greater than X" or "it is preferable that it is less than Y."

[0019] [toner] A toner according to an embodiment of the present invention (referred to as "the toner") is a toner having a core-shell structure, wherein the core and the shell each contain a binder resin, the binder resin of the core contains a styrene acrylic resin, and the binder resin of the shell contains an amorphous polyester resin, and when the binder resin of the shell is measured with a rheometer, the storage modulus at 70°C (G'(70°C)) (hereinafter may be simply referred to as "G'(70°C)") is 500,000 Pa or more, and the storage modulus at 100°C (G'(100°C)) (hereinafter may be simply referred to as "G'(100°C)") is 5,000 Pa or less.

[0020] The present toner contains a binder resin, and preferably further contains a colorant and a wax, and is preferably a toner comprising toner base particles (hereinafter referred to as "the present toner base particles") that contain a charge control agent and other components as needed, and an external additive. However, the toner is not necessarily limited to the above-mentioned composition. For example, it may not contain a colorant (clear toner), or it may not contain a charge control agent or external additives.

[0021] <Mechanism> The amorphous polyester resin used in the shell of the core-shell structure must have a certain degree of viscosity at low temperatures (approximately 50 to 70°C) to maintain storage stability, and must also have a lower viscosity and become softer at high temperatures (approximately 100 to 120°C) to ensure low-temperature fixability. In the present invention, an amorphous polyester resin is used for the shell, which can maintain high viscosity even at a lower melting point than styrene-acrylic resin due to intramolecular hydrogen bonding, etc., and the above-mentioned conflicting viscosity characteristics are defined by G'(70°C) and G'(100°C).When G'(70°C) is 500,000 Pa or more, good storage stability is maintained, and when G'(100°C) is 5,000 Pa or less, excellent low-temperature fixability is achieved. That is, in the present invention, by specifying the G'(70°C) and G'(100°C) of the binder resin constituting the shell, particularly the polyester resin preferably used as the binder resin for the shell, both storage stability and low-temperature fixability are achieved.

[0022] To explain in more detail the compatibility of storage stability and low-temperature fixability of the present invention, in the present invention, the toner has a core-shell structure, and a low-viscosity amorphous polyester resin forms a shell and is arranged on the outside of the toner particles, which makes it easier for the outermost part of the particles to become soft during fixing, thereby enabling fixing even at low temperatures. On the other hand, generally, when the viscosity of the outer shell is reduced, the core and shell become compatible with each other during the aging process. In other words, the core, which generally has a lower viscosity than the shell, becomes compatible with the reduced-viscosity shell, which further reduces the viscosity of the reduced-viscosity shell. As a result, the viscosity of the toner particle surface decreases and storage stability decreases significantly. In the present invention, by adopting a structure in which the core and shell are separated, low-temperature fixability is realized, and even if the viscosity of the shell is reduced to the lower limit at which storage stability can be maintained, compatibility between the shell and core can be suppressed during the aging process, so that the viscosity of the shell does not further decrease due to the influence of the lower-viscosity core, and storage stability is thought to be maintained. This phenomenon may also be due to the spacer effect, etc., which is caused by the shell being formed discontinuously on the surface of the core and taking a dispersed shape, reducing the contact area between toner particles and making it difficult for particles to fuse together when heat or pressure is applied. With regard to the above-described structure in which the core and shell are separated, it is an important constituent element that the styrene acrylic resin of the core and the amorphous polyester resin of the shell of the core-shell structure of the present toner are not modified polyester resins such as styrene acrylic modified polyester resin as in the aforementioned Patent Document 1. That is, in Patent Document 1, the shell and core are combined by modifying the polyester resin with styrene acrylic as a connecting portion between the core and shell, but in the present invention, for example, by not providing such a connecting portion and adopting a structure in which the core and shell are separated, the core is less susceptible to the influence of the shell and stable storage stability can be obtained.

[0023] As described above, in the present invention, a structure in which the core and the shell are separated is preferable, and in order to obtain such a structure, the toner composition can be, for example, as follows. 1) The content of styrene acrylic segments in the amorphous polyester resin of the shell is below a certain value. 2) The content of polyester segments in the styrene-acrylic resin of the core is below a certain value. 3) The ratio of the acid values ​​of the styrene acrylic resin in the core to the amorphous polyester resin in the shell ([acid value of the styrene acrylic resin in the core] / [acid value of the amorphous polyester resin in the shell]) is 0.85 or more and 2.9 or less. In the case of 1), the content of the styrene acrylic segment in the amorphous polyester resin of the shell is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the amorphous polyester resin. That is, it is more preferable that the amorphous polyester resin of the shell does not contain a styrene acrylic segment, in other words, it is not a styrene acrylic-modified polyester resin. In the case of 2), the content of the polyester segment in the styrene-acrylic resin of the core is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the styrene-acrylic resin. In other words, it is preferable that the styrene-acrylic resin of the core does not contain a polyester segment. Note that, for example, the following methods can be mentioned as a method for polymerizing the polyester segment into the styrene-acrylic resin, but any method can be used. 2-1) A method of reacting a bireactive monomer with a polyester polymer segment and then reacting a styrene-acrylic raw material monomer. 2-2) A method of reacting a styrene-acrylic resin with a bireactive monomer, followed by a polycarboxylic acid monomer and a polyhydric alcohol monomer. 2-3) A method in which a bireactive monomer is reacted with styrene acrylic resin and polyester resin to chemically bond them together. In the case of 3) above, the lower limit of the ratio of the acid values ​​of the styrene acrylic resin of the core to the amorphous polyester resin of the shell ([acid value of styrene acrylic resin of the core] / [acid value of amorphous polyester resin of the shell]) is more preferably 0.90 or more, and even more preferably 1.0 or more, and the upper limit is more preferably 2.5 or less, and even more preferably 2.0 or less. If the ratio exceeds the lower limit, the hydrophilicity of the shell becomes higher than that of the core, making it difficult for the shell to penetrate into the toner particles during the aging process, and if the ratio is below the upper limit, the hydrophilicity of the shell is not too high, making it possible to appropriately stabilize the dispersion of the amorphous polyester resin and thereby obtaining an appropriate core-shell separation structure.

[0024] <Toner base particles> In order to more effectively obtain the above-mentioned effects, it is preferable that the toner has a core-shell structure having a core containing a styrene acrylic resin as a binder resin and a shell containing an amorphous polyester resin as a binder resin that satisfies specific G'(70°C) and G'(100°C), in which the binder resin of the core is a styrene acrylic resin and the binder resin of the shell is the above-mentioned amorphous polyester resin.

[0025] In the present invention, the term "core-shell structure" refers to a structure in which the surface of a core component is covered with a shell component, but is not limited to a structure in which the core component is completely covered with the shell component, and the surface of the core component may be partially exposed, or may be partially dispersed in the shell component.

[0026] In any of the methods for preparing toner base particles described below, the shell component refers to a component that is unevenly distributed on the surface of the toner base particle. The shape of the shell component when made into a toner may be a fine particle or a thin film, and further, the shell component may cover the core component continuously or discontinuously.

[0027] When toner base particles are produced in a wet medium having an aqueous and / or organic solvent as a continuous phase, there are two methods: one is to add shell particles simultaneously with the core components and thermodynamically arrange the shell particles at the interface between the core components and the wet medium (method to control polarity), and the other is to add shell particles after the core components and physically arrange them on the surface of the core components.Furthermore, it is also possible to combine the method of thermodynamically arranging shell particles at the interface between the core components and the wet medium (method to control polarity) and the method of adding shell particles after the core components and physically arrange them on the surface of the core components.

[0028] In addition, when adding shell particles after the core component, a method of adding them after the composition and / or shape of the core component has been determined (the shape, physical properties, compatibility, etc. of the core component may change due to subsequent heating, aging, stirring, etc.) can also be used.

[0029] The toner base particles preferably contain a binder resin of styrene acrylic resin, and optionally a colorant and wax, and further preferably contain a charge control agent and other components in the core. The shell preferably contains a binder resin alone, but may optionally contain a colorant and wax, and further may contain a charge control agent and other components.

[0030] <Styrene acrylic resin> Styrene-acrylic resin (hereinafter sometimes abbreviated as "StAc") is a copolymer formed using a styrene-based monomer and a (meth)acrylic acid ester-based monomer. Preferably, the copolymer is formed using a (meth)acrylic acid-based monomer in addition to the styrene-based monomer and the (meth)acrylic acid ester-based monomer.

[0031] Examples of styrene-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-ethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 2,4-dimethylstyrene, dichlorostyrene, etc. These may be used alone or in combination of two or more. Among these, from the viewpoints of reactivity, ease of polymerization, and cost, styrene and p-methylstyrene are preferred, and styrene is more preferred.

[0032] Examples of (meth)acrylic acid ester monomers include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, cyclohexyl acrylate, heptyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, heptyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. These may be used alone or in combination of two or more. Among these, from the viewpoints of toner fixability, anti-offset properties, and cost, propyl acrylate, n-butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate are preferred, n-butyl acrylate and 2-ethylhexyl acrylate are more preferred, and n-butyl acrylate is even more preferred.

[0033] Examples of (meth)acrylic acid monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, cinnamic acid, etc. These can be used alone or in combination of two or more. Among these, from the viewpoints of reactivity and ease of polymerization, acrylic acid and methacrylic acid are preferred, and acrylic acid is more preferred.

[0034] The proportion of styrene-based monomers in 100% by mass of all monomers constituting the styrene-acrylic resin is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 65% ​​by mass or more from the viewpoint of storage stability of the toner, while it is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less from the viewpoint of fixability of the toner. The proportion of (meth)acrylic acid ester monomers in 100% by mass of all monomers constituting the styrene-acrylic resin is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more from the viewpoint of toner fixability, while it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less from the viewpoint of toner storage stability. The proportion of (meth)acrylic acid monomers in 100% by mass of all monomers constituting the styrene-acrylic resin is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.7% by mass or more, from the viewpoint of toner developability, while it is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and even more preferably 2.0% by mass or less, from the viewpoint of toner environmental stability.

[0035] The content ratio of the styrene-based monomer and the (meth)acrylic acid ester-based monomer constituting the styrene-based monomer is preferably 0.18 or more, more preferably 0.25 or more, and is preferably 0.67 or less, more preferably 0.54 or less. In particular, by setting the ratio in the range of 0.49 to 0.54, excellent low-temperature fixability can be achieved while maintaining storage stability at a practical level. The content ratio of the styrene-based monomer and the (meth)acrylic acid-based monomer constituting the styrene-acrylic resin is preferably 0.005 or more, more preferably 0.006 or more, of the (meth)acrylic acid-based monomer to the styrene-based monomer, and is preferably 0.035 or less, more preferably 0.03 or less.

[0036] Furthermore, other monomers can be used to make the styrene-acrylic resin have a crosslinked structure. Examples of other monomers include hexanediol diacrylate, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, and neopentyl glycol diacrylate. Among these, hexanediol diacrylate is preferred.

[0037] The styrene-acrylic resin preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 30,000 to 150,000 as measured by gel permeation chromatography (GPC). When the mass average molecular weight (Mw) of the styrene acrylic resin is 30,000 or more, sufficient heat-resistant storage stability can be obtained. When the weight average molecular weight (Mw) of the styrene acrylic resin is 150,000 or less, sufficient low-temperature fixability can be obtained. The method for measuring the mass average molecular weight (Mw) of the styrene acrylic resin is as described in the Examples section below.

[0038] The styrene-acrylic resin may be used alone, or two or more types having different monomer compositions, physical properties, etc. may be used in combination.

[0039] The content of the styrene acrylic resin in the toner is preferably 60 to 85% by mass, and more preferably 65 to 80% by mass, relative to the total mass (100% by mass) of the toner from the viewpoints of reducing the cost, environmental stability, fixability, and storage stability of the toner. If the content of the styrene acrylic resin is equal to or greater than the lower limit, there is a significant cost benefit, and environmental stability and storage stability under high-humidity conditions are maintained. If the content is equal to or less than the upper limit, the content of the amorphous polyester resin on the surface becomes sufficient, which is preferable from the viewpoints of improving adhesion to the medium and maintaining the storage stability of the toner.

[0040] <Amorphous polyester resin> The binder resin of the core of the toner satisfies specific G'(70°C) and G'(100°C) and contains an amorphous polyester resin (sometimes abbreviated as "amorphous PES"), and preferably consists of the amorphous polyester resin.

[0041] Amorphous polyester resin refers to a polyester resin that has a glass transition point (Tg) in an endothermic curve obtained by differential scanning calorimetry (DSC), but exhibits amorphous properties with no clear endothermic peak at the melting point, i.e., when the temperature rises.

[0042] The amorphous polyester resin is obtained by polycondensation reaction of polycarboxylic acid monomers (derivatives) and polyhydric alcohol monomers (derivatives) in the presence of a suitable polymerization catalyst. Examples of the polycarboxylic acid monomer derivatives include alkyl esters, acid anhydrides, and acid chlorides of polycarboxylic acid monomers, and examples of the polyhydric alcohol monomer derivatives include esters of polyhydric alcohol monomers and hydroxycarboxylic acids.

[0043] Examples of polycarboxylic acid monomers include oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, and p-carboxyphenyl Examples of suitable carboxylic acids include dicarboxylic acids such as acetic acid, p-phenylene diacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, and dodecenyl succinic acid; and tricarboxylic acids such as trimellitic acid, pyromellitic acid, naphthalene tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene tricarboxylic acid, and pyrene tetracarboxylic acid. These may be used alone or in combination of two or more. Among these, from the viewpoints of storage stability, handling properties, cost, and supply amount of the toner, preferred dicarboxylic acids are maleic acid, adipic acid, fumaric acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, isophthalic acid, and terephthalic acid, more preferred are adipic acid, isophthalic acid, and terephthalic acid, and even more preferred are isophthalic acid and terephthalic acid. As the tricarboxylic acid, trimellitic acid and pyromellitic acid are preferred, and trimellitic acid is more preferred, from the viewpoint of ease of adjusting the polymerization rate.

[0044] Examples of polyhydric alcohol monomers include dihydric alcohols such as ethylene glycol, neopentyl glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, octanediol, decanediol, dodecanediol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A; and trihydric or higher polyols such as glycerin, pentaerythritol, trimethylolpropane, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine. These may be used alone or in combination of two or more. Among these, from the viewpoints of reducing the colorability of the resin, ease of raw material availability, and charging properties, preferred dihydric alcohols are ethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A, more preferred are ethylene glycol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A, and even more preferred are ethylene glycol and a propylene oxide adduct of bisphenol A. As the trivalent or higher polyol, from the viewpoint of ease of adjusting the polymerization rate, glycerin, pentaerythritol, and trimethylolpropane are preferred, and trimethylolpropane is more preferred.

[0045] The ratio of polycarboxylic acid to polyhydric alcohol is preferably such that the equivalent ratio (OH) / (COOH) of the hydroxyl group (OH) of the polyhydric alcohol to the carboxyl group (COOH) of the polycarboxylic acid is within the range of 1.5 / 1 to 1 / 1.5.

[0046] An essential constituent requirement of the binder resin for the shell according to the present invention is that it has a G'(70°C) of 500,000 Pa or more. When the binder resin for the shell has a G'(70°C) of 500,000 Pa or more, excellent storage stability can be obtained. From the viewpoint of storage stability, the binder resin for the shell preferably has a G'(70°C) of 700,000 Pa or more, and more preferably has a G'(70°C) of 1,000,000 Pa or more. On the other hand, from the viewpoint of low-temperature fixability, the binder resin for the shell preferably has a G'(70°C) of 5,000,000 Pa or less, particularly preferably 3,000,000 Pa or less.

[0047] Furthermore, it is an essential constituent requirement that the shell binder resin used in the present invention has a G'(100°C) of 5000 Pa or less. When the shell binder resin has a G'(70°C) of 5000 Pa or less, excellent low-temperature fixability can be obtained. From the viewpoint of low-temperature fixability, the shell binder resin preferably has a G'(100°C) of 3000 Pa or less, more preferably 2000 Pa or less. On the other hand, from the viewpoint of storage stability, the shell binder resin preferably has a G'(100°C) of 500 Pa or more, particularly 1000 Pa or more. As described above, in the present invention, the binder resin of the shell is preferably made of an amorphous polyester resin, and therefore, the amorphous polyester resin constituting the shell preferably satisfies the above G'(70°C) and G'(100°C). The G'(70°C) and G'(100°C) of the binder resin are measured by the method described in the Examples section below.

[0048] In the present invention, in order to obtain a binder resin having such contradictory physical properties as G'(70°C) and G'(100°C), an amorphous polyester resin that satisfies the above G'(70°C) and G'(100°C) alone may be used as the binder resin for the shell, or an amorphous polyester resin that satisfies only the above G'(70°C) may be mixed with an amorphous polyester resin that satisfies only the above G'(100°C) so that the G'(70°C) and G'(100°C) of the resulting amorphous polyester resin mixture satisfy the above conditions.

[0049] The acid value of the amorphous polyester resin is preferably 6 mgKOH / g or more. When the acid value of the amorphous polyester resin is equal to or greater than the lower limit, sufficient stability is obtained for use as a polyester dispersion in the aggregation step of preparing toner base particles. On the other hand, it is preferable that the acid value of the amorphous polyester resin is 20 mgKOH / g or less from the viewpoint of ease of preparing particles having a polyester on the surface. The acid value of the amorphous polyester resin is more preferably 8 mgKOH / g or more, and even more preferably 10 mgKOH / g or more, and is more preferably 18 mgKOH / g or less, and even more preferably 15 mgKOH / g or less. The acid value of the amorphous polyester resin is measured by the method described in the Examples section below.

[0050] The glass transition temperature (Tg) of the amorphous polyester resin is preferably within the range of 50 to 65°C. If the glass transition temperature of the amorphous polyester resin is equal to or higher than the lower limit, the storage stability of the toner is maintained. If the glass transition temperature of the amorphous polyester resin is equal to or lower than the upper limit, the low-temperature fixability of the toner is not impaired, and the particle surfaces are easily covered uniformly during the aging process when preparing the toner base particles. The glass transition temperature of the amorphous polyester resin is more preferably 53°C or higher, even more preferably 55°C or higher, and is more preferably 63°C or lower, even more preferably 60°C or lower. The glass transition temperature of the amorphous polyester resin is measured by the method described in the Examples section below.

[0051] The softening temperature of the amorphous polyester resin is preferably within the range of 90 to 150°C. If the softening temperature of the amorphous polyester resin is equal to or higher than the lower limit, the storage stability of the toner is maintained. If the softening temperature of the amorphous polyester resin is equal to or lower than the upper limit, the low-temperature fixability of the toner is not deteriorated. The softening temperature of the amorphous polyester resin is more preferably 95°C or higher, even more preferably 100°C or higher, and is more preferably 135°C or lower, even more preferably 125°C or lower. The softening temperature of the amorphous polyester resin is measured by the method described in the Examples section below.

[0052] The present toner may contain only one type of amorphous polyester resin as the binder resin for the shell, or may contain two or more types of resins with different monomer compositions, physical properties, and the like.

[0053] The amorphous polyester resin is preferably contained in a proportion of 3% by mass or more and 40% by mass or less relative to the total mass of the toner. If the content of the amorphous polyester resin in the toner is 3% by mass or more, a toner with excellent storage stability can be obtained. From this perspective, the content of the amorphous polyester resin in the toner is particularly preferably 5% by mass or more, and even more preferably 8% by mass or more. On the other hand, if the content of the amorphous polyester resin in the toner is 40% by mass or less, a toner with excellent low-temperature fixability can be obtained. From this perspective, the content of the amorphous polyester resin in the toner is particularly preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0054] <Coloring agent> Any known colorant can be used as the colorant contained in the toner of the present invention. Specific examples of the colorant include carbon black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow, rhodamine dyes and pigments, chrome yellow, quinacridone dyes, benzidine yellow, rose bengal, triallylmethane dyes, monoazo dyes, disazo dyes, and condensed azo dyes and pigments, and any known dyes and pigments can be used alone or in combination. In the case of full-color toners, it is preferable to use monoazo-, disazo-, polyazo-, or condensed azo-based dyes and pigments for yellow, quinacridone- and / or monoazo-based dyes and pigments for magenta, phthalocyanine-based dyes and pigments for cyan, and carbon black for black. As a combination of toner sets, it is preferable that the magenta toner contains a quinacridone-based dyes and pigments and / or monoazo-based dyes and pigments, the black toner contains carbon black, the cyan toner contains a copper phthalocyanine-based dyes and pigments, and the yellow toner contains at least one dyes and pigments selected from monoazo-, disazo-, and condensed azo-based dyes and pigments. Specific examples of cyan include CI Pigment Blue 15:3 and CI Pigment Blue 15:4; examples of yellow include CI Pigment Yellow 74, CI Pigment Yellow 83, which is a disazo dye / pigment, and CI Pigment Yellow 93, CI Pigment Yellow 155, CI Pigment Yellow 180, and CI Pigment Yellow 185, which are condensed azo dye / pigment; and examples of magenta include CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 5, CI Pigment Red 122 and CI Pigment Red 209, which are quinacridone dye / pigment, and CI Pigment Red 269(238), which is a monoazo dye / pigment.

[0055] The colorant is preferably used in an amount of 3 to 20% by mass relative to the total mass (100% by mass) of the toner.

[0056] <Wax> The toner may further contain a wax, and by containing a wax, it is possible to improve low-temperature fixability and high-temperature offset property. The wax may be contained in any form in the toner, and for example, the wax may be present in a form in which the binder resin and the wax are partially or entirely compatible with each other, the core may be separated as a domain and encapsulated, the shell may be separated as a domain and encapsulated, or the wax may be present separated on the surface of the toner.

[0057] That is, by including wax, particularly crystalline wax, the wax melts instantly when the toner is heated, thereby improving fixability to the printing medium. Furthermore, when the wax is encapsulated separately from the core as a domain, it does not plasticize the toner, thereby maintaining storage stability. Specifically, when the wax is a crystalline wax with a clearer melting point than ordinary wax, its compatibility with the binder resin decreases, resulting in a structure in which the wax and the binder resin in the core are separated, making it less likely to plasticize the resin and maintaining storage stability.

[0058] The type of wax contained in the present toner is not limited, but it is preferable to contain an ester wax, and more preferable to contain a crystalline wax, which will be described later.

[0059] Examples of ester waxes include ester waxes having a long-chain aliphatic group, such as behenyl behenate, montanic acid ester, stearyl stearate, and erythritol tetrabehenate. Among these, monoester waxes containing primarily C18 and / or C22 hydrocarbons are more preferred, and among these, behenyl behenate, stearyl behenate, behenyl stearate, and those containing primarily these are particularly preferred from the viewpoints of low dust and low-temperature fixation. From the viewpoint of low dust, the number of carbon atoms in one molecule of the ester wax is preferably 36 or more, and more preferably 40 or more. On the other hand, from the viewpoint of low temperature fixation, the number of carbon atoms in one molecule of the ester wax is preferably 95 or less, more preferably 60 or less, even more preferably 48 or less, and particularly preferably 44 or less.

[0060] The crystalline wax suitable for use in the toner preferably has a melting peak (top of the endothermic peak in the second DSC heating of the toner) of 90°C or less, more preferably 85°C or less, even more preferably 80°C or less, preferably 50°C or more, more preferably 60°C or more, and even more preferably 65°C or more. If the wax melting peak temperature is too low, blocking resistance tends to deteriorate, while if the wax melting peak temperature is too high, low-temperature fixability and high gloss tend to be impaired. In addition, the difference between the wax melting peak and the wax onset temperature (the intersection temperature of the baseline before the endothermic peak and the tangent to the first inflection point that appears before the endothermic peak in the second DSC of the toner) is preferably 15°C or less, more preferably 10°C or less.

[0061] (Other waxes) The toner may contain other waxes in addition to the ester wax, or other waxes may be used in combination with the ester wax. Examples include olefin waxes such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, and copolymerized polyethylene; paraffin wax; vegetable waxes such as hydrogenated castor oil and carnauba wax; ketones having a long-chain alkyl group such as distearyl ketone; silicones having an alkyl group; higher fatty acids such as stearic acid; higher fatty acid amides such as oleic acid amide and stearic acid amide; etc. Preferred examples include hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax; and silicone waxes.

[0062] (amount of wax) The amount of wax contained in the toner is preferably 5 to 30% by mass, more preferably 10 to 20% by mass, based on the total mass (100% by mass) of the toner. In addition, out of the total wax content (100% by mass), the content of the low-temperature fixing wax is preferably 30% by mass or more, more preferably 40% by mass or more, and 80% by mass or less.

[0063] <Charge control agent> The present toner may contain a charge control agent to improve the charging characteristics of the toner. Any known charge control agent can be used. Specific examples of charge control agents include nigrosine dyes, amino group-containing vinyl copolymers, quaternary ammonium salt compounds, polyamine resins, etc. for positively chargeable agents, and metal-containing azo dyes containing metals such as chromium, zinc, iron, cobalt, and aluminum, as well as salts and metal complexes of salicylic acid or alkylsalicylic acid with the above-mentioned metals, etc. for negatively chargeable agents.

[0064] The amount of the charge control agent is preferably 0.1 to 25% by mass, more preferably 1 to 15% by mass, based on the total mass (100% by mass) of the toner. The charge control agent may be mixed inside the toner base particles, or may be attached to the surface of the toner base particles.

[0065] <External additives> The toner generally contains an external additive to improve the fluidity and charge controllability of the toner. The external additive is generally attached to the surface of the toner base particles, but the degree to which the external additive is embedded in the base particles may be in any state. That is, a part or all of the external additive may be attached to the base particle surface in a point-contact manner or embedded therein, and a part or all of the external additive may be present in a dispersed or aggregated state on the base particle surface. The particle size of the external additive particles is preferably such that the ratio (particle size of external additive particles) / (average particle size of toner base particles) is in the range of 0.1% to 5% of the average particle size of the toner base particles.

[0066] The external additive may be selected from various inorganic or organic fine particles and used in combination. Two or more types of external additives may also be used in combination.

[0067] Examples of inorganic fine particles that can be used include various carbides such as silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, and calcium carbide; various nitrides such as boron nitride, titanium nitride, and zirconium nitride; various borides such as zirconium boride; various oxides such as titanium oxide, calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, cerium oxide, silica, and colloidal silica; various titanate compounds such as calcium titanate, magnesium titanate, and strontium titanate; phosphate compounds such as calcium phosphate; sulfides such as molybdenum disulfide; fluorides such as magnesium fluoride and carbon fluoride; various metal soaps such as aluminum stearate, calcium stearate, zinc stearate, and magnesium stearate; talc, bentonite, various carbon blacks, conductive carbon blacks, magnetite, and ferrite.

[0068] Examples of organic fine particles that can be used include fine particles of styrene-based resins, acrylic-based resins, epoxy-based resins, and melamine-based resins. Fluorine-containing fine particles can also be used to improve charging stability. Among these external additives, silica, titanium oxide, alumina, zinc oxide, various carbon blacks, and conductive carbon black are particularly preferred. Furthermore, the external additives used may include inorganic or organic fine particles whose surfaces have been subjected to a surface treatment, such as hydrophobic treatment, using a treatment agent, such as a silane coupling agent (e.g., hexamethyldisilazane (HMDS) or dimethyldichlorosilane (DMDS)), a titanate-based coupling agent, a silicone oil treatment agent (e.g., silicone oil, dimethylsilicone oil, modified silicone oil, or amino-modified silicone oil), a silicone varnish, a fluorine-based silane coupling agent, a fluorine-based silicone oil, or a coupling agent having an amino group or a quaternary ammonium base. Two or more of these treatment agents can also be used in combination.

[0069] The amount of the external additive added is preferably 1.0 part by mass or more, particularly preferably 1.5 parts by mass or more, and is preferably 6.5 parts by mass or less, particularly preferably 5.5 parts by mass or less, relative to 100 parts by mass of the toner base particles.

[0070] In the present toner, from the viewpoint of charge control, conductive fine particles may be used as an external additive. Examples of conductive fine particles include metal oxides such as conductive titanium oxide, silica, and magnetite, or those doped with a conductive substance, organic fine particles obtained by doping a polymer having conjugated double bonds such as polyacetylene, polyphenylacetylene, and poly-p-phenylene with a conductive substance such as a metal, and carbon such as carbon black and graphite. However, from the viewpoint of imparting conductivity without impairing the fluidity of the toner, conductive titanium oxide or those doped with a conductive substance are more preferred.

[0071] The content of the conductive fine particles is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and particularly preferably 0.2 parts by mass or more, relative to 100 parts by mass of the toner base particles, and the upper limit of the content of the conductive fine particles is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and particularly preferably 1 part by mass or less.

[0072] <Form of this toner> From the viewpoint of image reproducibility and toner consumption, the volume median particle size of the present toner is preferably 6.5 μm or less, more preferably 6.3 μm or less, and even more preferably 6.0 μm or less. On the other hand, from the viewpoint of environmental safety with respect to dust, the volume median particle size of the present toner is preferably 3.0 μm or more, more preferably 4.0 μm or more, and even more preferably 4.5 μm or more. In the present invention, the "volume median particle size (Dv50)" is measured by the method described in the Examples section below and is defined as the value measured in this manner, and is also defined as the value measured on toner particles finally obtained in the production process, which include toner base particles and, if necessary, external additives.

[0073] Furthermore, in order to suppress fogging, white background smearing, etc. and to stably obtain high-quality images, the percentage by number of particles having a primary particle diameter of 1.0 μm or less is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less.

[0074] The shape of the toner is preferably such that the average circularity measured using a flow particle image analyzer FPIA-3000 (manufactured by Malvern Instruments) is 0.92 or more and 0.99 or less, more preferably 0.95 or more, and even more preferably 0.96 or more.

[0075] The percentage by number of particles having a particle size of 1.0 μm or less and the average circularity are measured by the method described in the Examples section below.

[0076] [Toner manufacturing method] The present toner can be produced by producing the present toner base particles by a known method, and then externally adding an external additive to the present toner base particles as required.

[0077] <Method of manufacturing the toner base particles> A method can be used in which each raw material is prepared as particles smaller than the toner base particles, and then these are mixed, aggregated, and aged to obtain toner base particles. For example, toner base particles can be obtained by mixing binder resin fine particles (primary polymer particles), colorant particles, and, if necessary, wax or charge control agent, and then aggregating and aging (thermal fusion), filtering, washing, and drying. The binder resin fine particles (primary polymer particles) can be obtained by emulsion polymerization, or by obtaining a binder resin by any polymerization method (bulk polymerization, solution polymerization, suspension polymerization, etc.) and then mixing it with an aqueous medium to emulsify. From the viewpoint that aggregating particles by an emulsion aggregation method performed in an aqueous system makes it easier to control the circularity of the final base particles, etc., primary polymer particles of styrene acrylic resin are preferably obtained by emulsion polymerization that gives an aqueous emulsion, and for the same reason, primary polymer particles of polyester resin are preferably obtained as an aqueous emulsion by the latter emulsification method. Furthermore, any of the above-mentioned methods for obtaining the primary polymer particles can be used both when preparing the primary polymer particles of the binder resin for the core and when preparing the primary polymer particles of the binder resin for the shell.

[0078] (Method for producing primary polymer particles: emulsion polymerization) For example, the primary polymer particles containing the raw material monomer of the styrene-acrylic resin as a constituent element can be obtained by emulsion polymerization of the monomer and, if necessary, an emulsifier, a polymerization initiator, and a chain transfer agent. Although known emulsifiers can be used, one or more emulsifiers selected from cationic surfactants, anionic surfactants, and nonionic surfactants can be used in combination. Among them, anionic surfactants are preferred from the viewpoints of ease of particle preparation, washability, and waste liquid treatment.

[0079] Examples of cationic surfactants include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, and hexadecyl trimethyl ammonium bromide.

[0080] Examples of anionic surfactants include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate.

[0081] Examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, and monodecanoyl sucrose.

[0082] The amount of emulsifier used is preferably 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of raw material monomer. If the amount of emulsifier used is increased, the particle size of the resulting polymer primary particles will be smaller, while if the amount used is decreased, the particle size of the resulting polymer primary particles will be larger. These emulsifiers can also be used in combination with one or more protective colloids, such as partially or completely saponified polyvinyl alcohols and cellulose derivatives such as hydroxyethyl cellulose.

[0083] As the polymerization initiator, known initiators can be used alone or in combination. Examples include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; redox initiators in which these persulfates are combined with a reducing agent such as sodium sulfite; water-soluble polymerization initiators such as hydrogen peroxide, 4,4'-azobiscyanovaleric acid, t-butyl hydroperoxide, and cumene hydroperoxide; redox initiators in which these water-soluble polymerization initiators are combined with a reducing agent such as a ferrous salt; benzoyl peroxide; and 2,2'-azobisisobutyronitrile. Among these, hydrogen peroxide is preferred from the standpoints of reactivity and cost. These polymerization initiators may be added to the polymerization system before, simultaneously with, or after the addition of the monomers; and these addition methods may be combined as necessary.

[0084] As the chain transfer agent, known agents can be used alone or in combination of two or more. For example, trichlorobromomethane, carbon tetrachloride, t-dodecyl mercaptan, 2-mercaptoethanol, etc. are used. Among them, trichlorobromomethane is preferred from the viewpoints of low molecular weight, sharp molecular weight distribution, and cost.

[0085] Among emulsion polymerization methods, so-called seed polymerization, in which wax is added as a seed during emulsion polymerization, is preferred. Seed polymerization allows the wax to be finely and uniformly dispersed in the toner, thereby preventing deterioration of the toner's chargeability and heat resistance. Alternatively, a wax-long-chain monomer dispersion can be prepared by dispersing wax and a long-chain monomer such as stearyl acrylate in an aqueous dispersion medium, and then polymerizing the monomer in the presence of the wax and long-chain monomer.

[0086] (Method of producing primary polymer particles: A method of obtaining a binder resin by any polymerization method, then mixing it with an aqueous medium and emulsifying it) After obtaining a binder resin by any polymerization method such as bulk polymerization, solution polymerization, or suspension polymerization, the binder resin is mixed with an aqueous medium and emulsified by applying shear force, thereby obtaining primary polymer particles of the binder resin.

[0087] Examples of emulsifiers for applying shear force include homogenizers, homomixers, pressure kneaders, extruders, and media dispersers. When the viscosity of the binder resin during emulsification is high and the primary polymer particles do not become small enough to reach the desired particle size, an emulsifier capable of pressurizing the resin to atmospheric pressure or higher is used to raise the temperature to the higher of either the melting point or the glass transition temperature of the resin, thereby emulsifying the resin in a state where the viscosity of the resin is reduced, thereby obtaining primary polymer particles having the desired particle size.

[0088] Another method for reducing the resin viscosity is to premix an organic solvent with the binder resin. The organic solvent used is not particularly limited as long as it dissolves the styrene-acrylic resin. Examples of suitable organic solvents include ketone-based solvents such as tetrahydrofuran (THF), methyl acetate, ethyl acetate, and methyl ethyl ketone, and benzene-based solvents such as benzene, toluene, and xylene. Furthermore, alcohol-based solvents such as ethanol and isopropyl alcohol may be added to the water or resin to improve compatibility with aqueous media and control particle size distribution. When an organic solvent is added, it must be removed from the emulsion after emulsification. Methods for removing the organic solvent include volatilizing the organic solvent at room temperature or under reduced pressure with heating.

[0089] For the purpose of controlling particle size distribution, salts such as sodium chloride and potassium chloride, ammonia, etc. may be added, and an emulsifier or dispersant may also be added. Examples of the emulsifier and dispersant used here include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, and sodium polyacrylate; the emulsifiers mentioned above; and inorganic compounds such as tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, and barium carbonate. The amount used is preferably 0.01 to 20 parts by mass per 100 parts by mass of the binder resin.

[0090] In addition to the above-mentioned methods, a phase inversion emulsification method may be used as a method for emulsifying a binder resin obtained by any polymerization method by mixing it with an aqueous medium. The phase inversion emulsification method involves adding an organic solvent, a neutralizing agent, and a dispersion stabilizer to the binder resin as needed, adding an aqueous medium dropwise under stirring to obtain emulsified particles, and then removing the organic solvent from the resin dispersion to obtain an emulsion. The organic solvent may be the same as the organic solvent described above. The neutralizing agent may be a common acid or alkali such as nitric acid, hydrochloric acid, sodium hydroxide, or ammonia.

[0091] (Particle size and molecular weight of primary polymer particles) The median diameter (D50) of the polymer primary particles of the binder resin is preferably 100 nm or more, more preferably 150 nm or more, and even more preferably 180 nm or more, and is preferably 350 nm or less, more preferably 300 nm or less, and even more preferably 280 nm or less. The mass average molecular weight (Mw) of the primary polymer particles of the binder resin is preferably 30,000 or more, more preferably 40,000 or more, and even more preferably 50,000 or more, and is preferably 500,000 or less, more preferably 300,000 or less, and even more preferably 150,000 or less. The median diameter (D50) and mass average molecular weight (Mw) of the primary polymer particles of the binder resin are measured by the method described in the Examples section below.

[0092] (Agglutination process) In the aggregation step, the polymer primary particles, and optionally colorant particles, a charge control agent, wax, etc., are mixed simultaneously or sequentially. From the viewpoint of uniformity of composition and particle size, it is preferable to prepare dispersions of the respective components in advance, i.e., a polymer primary particle dispersion, optionally a colorant particle dispersion, a charge control agent dispersion, and a wax microparticle dispersion, and then mix them to obtain a mixed dispersion.

[0093] When the toner base particles have a core-shell structure, the primary polymer particles of the binder resin for the core and the primary polymer particles of the binder resin for the shell may be charged at the same time, or a part or all of the primary polymer particles of the binder resin for the core may be aggregated with other components, and then the primary polymer particles of the binder resin for the shell may be added.

[0094] When primary polymer particles of a core binder resin (also referred to as a core component) and primary polymer particles of a shell binder resin (also referred to as a shell component) are charged simultaneously, the shell component will spontaneously adhere to the periphery of the core component if the polarity of the shell component is designed so that it is thermodynamically intermediate between the polarity of the core component and that of the medium (for example, water). When the shell component is adhered in a wet medium such as water and / or an organic solvent, it is preferable to add the shell component after the composition of the raw material of the core component has been determined (when toner base particles are produced by aggregating particles smaller than the toner base particles, part or all of the core component has been aggregated), from the viewpoint of arranging the shell component more closely on the surface of the core component.

[0095] The shell component may be added once or multiple times. The shell component added in the first addition may be different from the shell component added in the subsequent additions, and any combination may be used. In order to increase the stability of the core-shell structured particle aggregates obtained in the aggregation step, it is preferable to fuse the aggregated particles in the aging step after the aggregation step.

[0096] The colorant particles are preferably used in a state dispersed in water in the presence of an emulsifier, and the volume average particle size of the colorant particles is preferably 0.01 μm or more, particularly preferably 0.05 μm or more, and preferably 3 μm or less, particularly preferably 1 μm or less.

[0097] In the aggregation step, aggregation is usually carried out in a tank equipped with a stirring device, and there are methods of aggregation by heating, aggregation by adding an electrolyte, and a combination of these methods.

[0098] When an electrolyte is added to perform aggregation, the electrolyte may be any of an acid, alkali, or salt, and may be either organic or inorganic, but specific examples include acids such as hydrochloric acid, nitric acid, sulfuric acid, citric acid, etc.; alkalis such as sodium hydroxide, potassium hydroxide, aqueous ammonia, etc.; and salts such as NaCl, KCl, LiCl, Na2SO4, K2SO4, Li2SO4, MgCl2, CaCl2, MgSO4, CaSO4, ZnSO4, Al2(SO4)3, Fe2(SO4)3, CH3COONa, CH5SO3Na, etc. Among these, inorganic salts having a divalent or higher polyvalent metal cation are preferred.

[0099] The amount of electrolyte added varies depending on the type of electrolyte, the target particle size, etc., but is preferably 0.02 parts by mass or more, more preferably 0.05 parts by mass or more, relative to 100 parts by mass of the solid components of the mixed dispersion, and is preferably 25 parts by mass or less, more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. When aggregation is carried out by adding an electrolyte, the aggregation temperature is preferably 20°C or higher, particularly preferably 30°C or higher, and preferably 70°C or lower, particularly preferably 60°C or lower.

[0100] The time required for aggregation is optimized depending on the shape of the apparatus and the processing scale, but in order for the particle size of the toner base particles to reach the target particle size, it is preferable to maintain the temperature at the above-mentioned predetermined temperature for at least 30 minutes. The temperature may be increased at a constant rate or increased in stages until the predetermined temperature is reached.

[0101] (ripening process) In the aging step, the mixed dispersion obtained in the aggregation step is heated under sufficient stirring conditions. In the case of a core-shell structure, the temperature in the aging step is preferably equal to or higher than the Tg of the primary polymer particles of the shell binder resin, more preferably equal to or higher than the Tg of the primary polymer particles of the shell binder resin. The time required for the aging step varies depending on the shape of the target toner base particles, but it is desirable to maintain the temperature for preferably 0.1 to 10 hours, particularly preferably 0.5 to 5 hours, after the temperature reaches equal to or higher than the Tg of the primary polymer particles of the shell binder resin.

[0102] After the aggregation step, preferably before or during the aging step, it is preferable to add a surfactant, adjust the pH, or use both. The surfactant used here can be one or more selected from emulsifiers that can be used in producing the polymer primary particles, and it is particularly preferable to use the same emulsifier as that used in producing the polymer primary particles.

[0103] The amount of surfactant to be added is not limited, but is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass, relative to 100 parts by mass of the solid components of the mixed dispersion. The following is the result.

[0104] By adding a surfactant or adjusting the pH after the aggregation step and before the completion of the aging step, it is possible to suppress the aggregation of the particle aggregates obtained in the aggregation step, and in some cases it is possible to suppress the generation of coarse particles in the aging step.

[0105] By controlling the time of the aging process, it is possible to produce toner base particles of various shapes depending on the purpose, such as grape-shaped particles in which the aggregated shape of the polymer primary particles is maintained, potato-shaped particles in which fusion has progressed, and spherical particles in which fusion has progressed even further.

[0106] <Method of adding external additives> Examples of methods for adding external additives include a method using a high-speed mixer such as a Henschel mixer, and a method using a device capable of applying compressive shear stress. The toner can be produced by a one-stage external addition method in which all external additives are added to the toner base particles at the same time, or by a separate-stage external addition method in which the external additives are added separately. To prevent the temperature from rising during the external addition, a cooling device may be installed in the vessel, or external addition may be carried out in stages.

[0107] [Usage form] The present toner may be used in either the form of a two-component developer in which a toner is used together with a carrier, or a magnetic or non-magnetic one-component developer in which no carrier is used. When used as a two-component developer, the carrier may be a magnetic substance such as iron powder, magnetite powder, ferrite powder, or the like, or a known substance such as a magnetic carrier or a resin-coated magnetic substance. The coating resin of the resin-coated carrier may be a commonly known styrene resin, acrylic resin, styrene-acrylic copolymer resin, silicone resin, modified silicone resin, fluororesin, or a mixture thereof.

[0108] [Cartridges and image forming devices] Next, an embodiment of an image forming apparatus using the toner (image forming apparatus of the present invention) will be described. However, the embodiment is not limited to the following description, and can be modified as desired without departing from the gist of the present invention.

[0109] The image forming apparatus is configured to include an electrophotographic photosensitive member, a charging device, an exposure device, a developing device, and a toner, and may further include a transfer device, a cleaning device, and a fixing device as required.

[0110] The electrophotographic photosensitive member is not particularly limited, but for example, a drum-shaped photosensitive member having the above-described photosensitive layer formed on the surface of a cylindrical conductive support can be used. The charging device is a device for uniformly charging the surface of the electrophotographic photosensitive member to a predetermined potential. Typical charging devices include non-contact corona charging devices such as corotrons and scorotrons, and contact charging devices.

[0111] The type of the exposure device is not particularly limited as long as it can expose an electrophotographic photosensitive member to light to form an electrostatic latent image on the photosensitive surface of the electrophotographic photosensitive member. The transfer device applies a predetermined voltage (transfer voltage) with a polarity opposite to the charged potential of the toner, and transfers the toner image formed on the electrophotographic photosensitive member onto recording paper (paper, medium). There are no particular limitations on the type of transfer device, and any device using any method, such as corona transfer or roller transfer, can be used. The cleaning device scrapes off residual toner adhering to the electrophotographic photosensitive member with a cleaning member and collects the residual toner. However, if there is little or almost no toner remaining on the surface of the electrophotographic photosensitive member, a cleaning device may not be necessary. There are no particular restrictions on the cleaning device, and any cleaning device such as a brush cleaner, a magnetic roller cleaner, or a blade cleaner can be used.

[0112] In the image forming apparatus configured as above, an image is recorded as follows.

[0113] First, the surface (photosensitive surface) of the electrophotographic photoreceptor is charged to a predetermined potential by a charging device. At this time, charging may be performed by a DC voltage or by superimposing an AC voltage on the DC voltage. Next, the charged photosensitive surface of the electrophotographic photoreceptor is exposed to light by an exposure device in accordance with the image to be recorded, forming an electrostatic latent image on the photosensitive surface, and then the electrostatic latent image formed on the photosensitive surface of the electrophotographic photoreceptor is developed by a development device. The developing device forms a thin layer of toner using a regulating member such as a developing blade, frictionally charges the toner to a predetermined polarity, and transports the toner while being carried by a developing roller, bringing the toner into contact with the surface of an electrophotographic photosensitive member.

[0114] When the charged toner carried on the developing roller comes into contact with the surface of the electrophotographic photosensitive member, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the electrophotographic photosensitive member. This toner image is then transferred onto recording paper or the like by a transfer device. After this, toner that has not been transferred and remains on the photosensitive surface of the electrophotographic photosensitive member is removed by a cleaning device. After the toner image is transferred to a printing medium such as recording paper, the toner image is passed through a fixing device to be thermally fixed to the printing medium such as recording paper, thereby obtaining a final image. In addition to the above-described configuration, the image forming apparatus may be configured to be capable of performing, for example, a charge removal process. The charge removal process is a process of removing charge from an electrophotographic photosensitive member by exposing the electrophotographic photosensitive member to light.

[0115] Furthermore, the image forming apparatus may be further modified and configured, for example, to be capable of performing processes such as a pre-exposure process and an auxiliary charging process, or to be configured to perform offset printing, or even to be configured as a full-color tandem system using multiple types of toner.

[0116] In addition, a member for storing toner may be combined with one or more of a charging device, an exposure device, a developing device, a transfer device, a cleaning device, and a fixing device to form an integrated cartridge (hereinafter referred to as a "toner cartridge" as appropriate), and this toner cartridge may be configured to be detachable from the main body of an image forming device such as a copier or laser beam printer. The toner is applied to this toner cartridge to constitute the toner cartridge of the present invention.

[0117] [Print media] There are no particular limitations on the print media on which printing is performed using the present toner, and any media generally used in image forming devices may be used, such as general printing paper (including cardboard, postcards, envelopes, plain paper, thin paper, etc.), resin (plastic) such as PET or metal coated paper, OHP sheets, OHP film, tracing paper, etc. Of these, the present toner is particularly suitable for prints using PET coated paper, as it has excellent adhesion to PET coated paper. [Example]

[0118] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the following examples and comparative examples, "parts" simply means "parts by mass."

[0119] The methods for measuring various physical properties are as follows.

[0120] <Median diameter (D50) of primary polymer particles, wax, and colorants (pigments)> The median diameter (D50) of the polymer primary particles, wax, and colorant (pigment) was measured using a Microtrac Nanotrac 150 (hereinafter referred to as Nanotrac) manufactured by Nikkiso Co., Ltd. and the company's analysis software, Microtrac Particle Analyzer Ver. 10.1.2-0.19EE. The measurement was performed using ion-exchanged water with an electrical conductivity of 0.5 μS / cm as the solvent, with a solvent refractive index of 1.333, a measurement time of 120 seconds, and five measurements, according to the method described in the instruction manual, and the average value was calculated. Other setting conditions were particle refractive index of 1.59, transparency, shape: spherical, and density: 1.04.

[0121] <Volume median particle size of toner (Dv50)> The volume median particle size (Dv50) of the toner was measured using a Beckman Coulter Multisizer III (aperture diameter: 100 μm or less, abbreviated as Multisizer). The toner was dispersed in Beckman Coulter's Isoton II as the dispersion medium, with the dispersoid concentration set to 0.03% by mass. The measurement results are shown as "volume particle size."

[0122] <Average circularity and percentage of particles with a particle size of 1.0 μm or less> The average circularity and the percentage of particles with a diameter of 1.0 μm or less were measured by dispersing the dispersoid in a dispersion medium (Celsius, manufactured by Malvern Instruments) at 5720 to 7140 particles / μL and using a flow particle analyzer (FPIA3000, manufactured by Malvern Instruments) in HPF mode under conditions of an HPF analysis volume of 0.35 LL and an HPF detection volume of 2000 to 2500 particles. The measurement results were shown as "circularity" and "% number of particles with a diameter of 1.0 μm or less."

[0123] <Mass average molecular weight (Mw)> The styrene-acrylic dispersion liquid described below was freeze-dried to remove water, and then the THF-soluble components were measured by gel permeation chromatography (GPC) under the following conditions. Equipment: Tosoh GPC equipment HLC-8320 Column: TOSOH TSKgel SuperHM-H (diameter 6 m x length 150 mm x 2) Solvent: THF Column temperature: 40℃ Flow rate: 0.5mL / min Sample concentration: 0.1% by mass Calibration curve: Standard polystyrene

[0124] <Emulsion solids concentration> The solid content concentration of the emulsion was determined by heating 2 g of the sample at 195°C for 90 minutes to evaporate the water using an infrared moisture meter FD-610 manufactured by Kett Electric Laboratory.

[0125] <Glass transition temperature (Tg)> The glass transition temperature of the amorphous polyester resin was measured using a differential scanning calorimeter (Shimadzu Corporation, "DSC-60") from the intersection of the baseline of the chart and the tangent to the endothermic curve at a heating rate of 5°C / min. 10 mg ± 0.5 mg of the sample was weighed into an aluminum pan, melted at 100°C (above the glass transition temperature) for 10 minutes, and then rapidly cooled using dry ice.

[0126] <Softening temperature (T4)> The softening temperature of the amorphous polyester resin was measured using a flow tester (Shimadzu Corporation, "CFT-500D") with a 1 mmφ × 10 mm nozzle, a load of 294 N, and a uniform temperature increase rate of 3°C / min, at which the temperature at which half of a 1.0 g resin sample flowed out was measured, and this was taken as the softening temperature.

[0127] <Acid value> The acid value of the amorphous polyester resin was measured as follows. Approximately 0.2 g of the sample to be measured was accurately weighed into a sidearm Erlenmeyer flask (a(g)), 20 mL of benzyl alcohol was added, and the mixture was heated in a nitrogen atmosphere using a heater at 230°C for 15 minutes to dissolve the sample. After cooling to room temperature, 20 mL of chloroform and a few drops of cresol red solution were added, and the mixture was titrated with 0.02 N KOH solution (titer = b (mL), titer of KOH solution = p). A blank measurement was performed in the same manner (titer = c (mL)), and the acid value was calculated according to the following formula. Acid value (mgKOH / g)={(bc)×0.02×56.11×p} / a

[0128] <Storage modulus (G')> The resin used in the dynamic viscoelasticity measurement was a solid obtained by vacuum drying the amorphous polyester dispersion obtained in the following example. Dynamic viscoelasticity measurements were carried out using a rheometer ARES manufactured by TA Instruments as follows. Approximately 1.3 g of sample was placed in a 25 mm diameter jig and pressed with a 30 kg load for 10 minutes using a press heated to 50°C to form a pellet. The resulting pellet was placed in a measuring device equipped with circular parallel plates with a diameter of 25 mm, and the upper plate was lowered while the temperature was raised to 120°C to adjust the thickness of the pellet to 3.0 to 3.5 mm. The temperature was then lowered, and measurements were taken under the following conditions: measurement frequency 6.28 rad / s, initial temperature 40°C, pre-measurement delay time 3 minutes, automatic tension adjustment (pulling direction, initial force 0, automatic tension sensitivity 2.0 g, automatic tension switching elastic modulus 1.0E+08 Pa), final temperature 150°C, heating rate 4°C / min, measurement cycle time 1 minute, initial strain 0.1%, and automatic strain adjustment.

[0129] Next, the wax dispersion, colorant dispersion, and polymer primary particle dispersion (styrene acrylic dispersion, amorphous polyester dispersion) used in the examples and comparative examples will be described.

[0130] <Wax dispersion W1> The wax used was ester wax 1 (chemical formula C21H 43 COOC 22 H 45 30 parts of a 20% aqueous solution of sodium dodecylbenzenesulfonate (hereinafter referred to as 20% aqueous DBS solution), 1.93 parts of a 20% aqueous solution of sodium dodecylbenzenesulfonate, and 68.7 parts of demineralized water were placed in a CSTR-type stirring vessel equipped with a 45-degree inclined three-stage paddle blade, heated to 90°C in the stirring vessel, and mixed for 20 minutes. Next, while this dispersion was heated to 90°C, it was subjected to circulating emulsification under a pressure of 25 MPa using a valve homogenizer (Gaulin, 15-M-8PA type). The particle size was measured using a Nanotrac and the dispersion was continued until the median diameter (D50) reached 245 nm, producing wax dispersion W1 (emulsion solids concentration: 30.5%).

[0131] <Wax dispersion W2> Wax dispersion W2 (emulsion solids concentration: 30.5%) was prepared in the same manner as W1, except that 30 parts of ester wax 2 (stearyl behenate, melting point 67°C), 1.93 parts of a 20% DBS aqueous solution, and 68.7 parts of demineralized water were used.

[0132] <Wax dispersion W3> Wax dispersion W3 (emulsion solids concentration: 30.2%) was prepared in the same manner as W1, except that 30 parts of ester wax 3 (NOF Corporation, product name: WEP-3, melting point 73°C, acid value 0.1 mgKOH / g, hydroxyl value 3 mgKOH / g or less (all catalog values)), 0.24 parts of decaglycerin decabehenate (Mitsubishi Chemical Foods Corporation, product name: B100D, hydroxyl value 27, melting point 70°C), 1.93 parts of 20% DBS aqueous solution, and 67.83 parts of demineralized water were used.

[0133] <Colorant dispersion G1> 24 parts of Pigment Blue 15:3 (Dainichiseika Color & Chemicals Co., Ltd., cyan pigment (copper phthalocyanine complex)) as a colorant, 1 part of a 20% DBS aqueous solution, 9 parts of a nonionic surfactant (Kao Corporation, Emulgen 120), and 67 parts of ion-exchanged water with a conductivity of 2 μS / cm were added to a propeller-equipped agitator vessel and pre-dispersed to obtain a pigment premix. This premix was fed as a raw material slurry to a wet bead mill and dispersed. The wet bead mill's stator had an inner diameter of 120 mm and a separator diameter of 60 mm. Zirconia beads with a diameter of 0.1 mm were used as dispersion media. The effective internal volume of the stator was approximately 2 liters, and the media filling volume was 1.4 liters, resulting in a media filling rate of 70%. The rotor rotation speed was kept constant (the peripheral speed of the rotor tip was approximately 11 m / sec), and the raw material slurry was supplied from the supply port at a supply rate of approximately 40 liters / hr using a non-pulsating metering pump.When the predetermined particle size was reached, dispersion was stopped, and colorant dispersion G1 was obtained from the discharge port. During operation, cooling water at about 10° C. was circulated from the jacket. The dispersion median diameter (D50) of the colorant was 83 nm, the dispersion solid content was 34.3%, and the colorant solid content was 24.1%.

[0134] <Styrene acrylic dispersion A1> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices was charged with 70.7 parts of wax dispersion W2, 269 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate, and the temperature was raised to 70°C under a nitrogen stream while stirring. Then, with stirring continued, the following mixture of monomers and emulsifier solution was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was considered the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, 300 minutes after the start of polymerization, the internal temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring continued until 540 minutes after the start of polymerization.

[0135] (monomers) Styrene 65.5 parts Butyl acrylate 34.5 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 parts Hexanediol diacrylate 0.60 parts

[0136] (emulsifier aqueous solution) ·20% DBS aqueous solution 1.0 part 66.7 parts demineralized water (Aqueous initiator solution) 15.5 parts 8% hydrogen peroxide solution 8% L-(+) ascorbic acid aqueous solution 30.1 parts (iron sulfate aqueous solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0137] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A1. The median diameter (D50) of the primary polymer particles measured using a Nanotrac was 231 nm. The mass average molecular weight (Mw) of the primary polymer particles was 74,822. The acid value of this styrene-acrylic resin was calculated from the amount of acrylic acid added and was 7.3 mg KOH / g.

[0138] <Styrene acrylic dispersion A2> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices was charged with 70.7 parts of wax dispersion W2, 269 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate, and the temperature was raised to 70°C under a nitrogen stream while stirring. Then, with stirring continued, the following mixture of monomers and emulsifier solution was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was considered the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, 300 minutes after the start of polymerization, the internal temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring continued until 540 minutes after the start of polymerization.

[0139] (monomers) Styrene 68.2 parts Butyl acrylate 31.8 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 parts Hexanediol diacrylate 0.60 parts

[0140] (emulsifier aqueous solution) ·20% DBS aqueous solution 1.0 part 66.7 parts demineralized water (Aqueous initiator solution) 15.5 parts 8% hydrogen peroxide solution 8% L-(+) ascorbic acid aqueous solution 30.1 parts (iron sulfate aqueous solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0141] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A2. The median diameter (D50) of the primary polymer particles measured using a Nanotrac was 234 nm. The mass average molecular weight (Mw) of the primary polymer particles was 94164. The acid value of this styrene-acrylic resin was calculated from the amount of acrylic acid added and was 7.3 mg KOH / g.

[0142] <Styrene acrylic dispersion A3> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices was charged with 70.7 parts of wax dispersion W1, 269 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate, and the internal temperature was raised to 70°C under a nitrogen stream while stirring. Then, with stirring continued, the following mixture of monomers and emulsifier solution was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was considered the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, 300 minutes after the start of polymerization, the internal temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring continued until 540 minutes after the start of polymerization.

[0143] (monomers) Styrene 68.2 parts Butyl acrylate 31.8 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 parts Hexanediol diacrylate 0.60 parts

[0144] (emulsifier aqueous solution) ·20% DBS aqueous solution 1.0 part 66.7 parts demineralized water (Aqueous initiator solution) 15.5 parts 8% hydrogen peroxide solution 8% L-(+) ascorbic acid aqueous solution 30.1 parts (iron sulfate aqueous solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0145] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A3. The median diameter (D50) of the primary polymer particles measured using a Nanotrac was 216 nm. The mass average molecular weight (Mw) of the primary polymer particles was 80649. The acid value of this styrene-acrylic resin was calculated from the amount of acrylic acid added and was 7.3 mg KOH / g.

[0146] <Styrene acrylic dispersion A4> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices was charged with 35.3 parts of wax dispersion W1, 258 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate, and the temperature was raised to 70°C under a nitrogen stream while stirring. Then, with stirring continued, the following mixture of monomers and emulsifier solution was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was considered the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, 300 minutes after the start of polymerization, the internal temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring continued until 540 minutes after the start of polymerization.

[0147] (monomers) Styrene 70.0 parts Butyl acrylate 30.0 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 parts Hexanediol diacrylate 0.60 parts

[0148] (emulsifier aqueous solution) ·20% DBS aqueous solution 1.0 part 66.7 parts demineralized water (Aqueous initiator solution) 15.5 parts 8% hydrogen peroxide solution 8% L-(+) ascorbic acid aqueous solution 30.1 parts (iron sulfate aqueous solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0149] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A4. The median diameter (D50) of the primary polymer particles measured using a Nanotrac was 230 nm. The mass average molecular weight (Mw) of the primary polymer particles was 81608. The acid value of this styrene-acrylic resin was calculated from the amount of acrylic acid added and was 7.3 mg KOH / g.

[0150] <Styrene acrylic dispersion A5> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices was charged with 34.8 parts of wax dispersion W3, 258 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate, and the internal temperature was raised to 70°C under a nitrogen stream while stirring. Then, with stirring continued, the following mixture of monomers and emulsifier solution was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was considered the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, 300 minutes after the start of polymerization, the internal temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring continued until 540 minutes after the start of polymerization.

[0151] (monomers) Styrene 76.8 parts Butyl acrylate 23.2 parts Acrylic acid 1.5 parts Trichlorobromomethane 1.0 parts Hexanediol diacrylate 0.60 parts

[0152] (emulsifier aqueous solution) ·20% DBS aqueous solution 1.0 part 66.7 parts demineralized water (Aqueous initiator solution) 15.5 parts 8% hydrogen peroxide solution 8% L-(+) ascorbic acid aqueous solution 30.1 parts (iron sulfate aqueous solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0153] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A5. The median diameter (D50) of the primary polymer particles measured using a Nanotrac was 234 nm. The mass-average molecular weight (Mw) of the primary polymer particles was 75,601. The acid value of this styrene-acrylic resin was calculated from the amount of acrylic acid added to be 11.4 mg KOH / g, and the storage modulus (G') of the resin was G' (70°C) = 1,120,000 Pa, G' (100°C) = 10,800 Pa.

[0154] <Amorphous polyester resin> Amorphous polyester resins A, B, C, and D were produced as follows. A polycarboxylic acid component, a polyhydric alcohol component, and a polymerization catalyst were charged into a reaction vessel equipped with a distillation column, with the charge compositions shown in Table 1. The amount of the polymerization catalyst is the amount (ppm) relative to the acid component. Next, the rotation speed of the stirring blade in the reaction vessel was maintained at 120 rpm, and the temperature was started to rise until the temperature in the reaction system reached 265°C, and the esterification reaction was carried out by maintaining this temperature. After the distillation of water from the reaction system ceased and the esterification reaction was completed, the temperature in the reaction system was lowered to 240°C, and the pressure in the reaction vessel was reduced over approximately 40 minutes to a vacuum degree of 133 Pa, and a polycondensation reaction was carried out while distilling the alcohol component from the reaction system. The viscosity of the reaction system increased with the reaction, and the degree of vacuum was increased as the viscosity increased, and the condensation reaction was carried out until the torque of the stirring blade reached a value indicating the desired softening temperature. Then, when the predetermined torque was reached, the stirring was stopped, the reaction system was returned to normal pressure, and pressurized with nitrogen to remove (discharge) the reaction product from the reaction vessel, and each amorphous polyester resin was obtained. The physical properties (glass transition temperature, softening temperature, acid value) of the obtained amorphous polyester resins A, B, C, and D were measured. The results are shown in Table 1.

[0155] In Table 1, "BPA-PO 2.3 mol added" and "BPA-EO 2.3 mol added" have the following meanings. BPA-PO2.3 mol adduct: Propylene oxide derivative of bisphenol A (polyoxypropylene-(2.3)-2,2-bis(4-hydroxyphenyl)propane (PO2.3 mol adduct)) BPA-EO 2.3 mol adduct: Ethylene oxide derivative of bisphenol A (polyoxyethylene-(2.3)-2,2-bis(4-hydroxyphenyl)propane, (EO 2.3 mol adduct))

[0156] [Table 1]

[0157] <Amorphous polyester dispersion P1> 12.5 parts of amorphous polyester resin A and 12.5 parts of amorphous polyester resin B were dissolved in 75 parts of methyl ethyl ketone (MEK), and 19.9 g of a 5% aqueous ammonia solution was added and stirred uniformly with a stirrer to prepare a resin solution. Next, 100 parts of demineralized water was placed in a round-bottom flask, and the prepared resin solution was further added thereto, followed by dispersion with a homogenizer (T25 model, manufactured by IKA) at a rotation speed of 8,000 rpm for 10 minutes. The solvent was then removed by vacuum distillation at 80°C using an aspirator, yielding amorphous polyester dispersion P1. The median diameter (D50) of the primary polymer particles of the polyester resin particles in polyester dispersion P1 was measured using a Nanotrac and found to be 182 nm. The storage modulus (G') of the resin was G'(70°C) = 1,008,200 Pa, G'(100°C) = 1,176 Pa.

[0158] <Amorphous polyester dispersion P2> A resin solution was prepared by dissolving 8.3 parts of amorphous polyester resin A and 16.7 parts of amorphous polyester resin B in 75 parts of methyl ethyl ketone (MEK), adding 18.9 g of a 5% aqueous ammonia solution, and stirring uniformly with a stirrer. Next, 100 parts of demineralized water was placed in a round-bottom flask, and the prepared resin solution was further added thereto, followed by dispersion with a homogenizer (T25 model, manufactured by IKA) at a rotation speed of 8,000 rpm for 10 minutes. The solvent was then removed by vacuum distillation at 80°C using an aspirator, yielding amorphous polyester dispersion P2. The median diameter (D50) of the primary polymer particles of the amorphous polyester resin particles in amorphous polyester dispersion P2 was measured using a Nanotrac analyzer and found to be 190 nm. The storage modulus (G') of the amorphous polyester resin was G'(70°C) = 505,390 Pa, G'(100°C) = 987 Pa.

[0159] <Amorphous polyester dispersion P3> A resin solution was prepared by dissolving 16.7 parts of amorphous polyester resin A and 8.3 parts of amorphous polyester resin B in 75 parts of methyl ethyl ketone (MEK), adding 20.8 g of a 5% aqueous ammonia solution, and stirring uniformly with a stirrer. Next, 100 parts of demineralized water was placed in a round-bottom flask, and the prepared resin solution was further added thereto, followed by dispersion with a homogenizer (T25 model, manufactured by IKA) at a rotation speed of 8,000 rpm for 10 minutes. The solvent was then removed by vacuum distillation at 80°C using an aspirator, yielding Amorphous Polyester Dispersion P3. The median diameter (D50) of the primary polymer particles of the amorphous polyester resin particles in Amorphous Polyester Dispersion P3 was measured using a Nanotrac analyzer and found to be 188 nm. The storage modulus (G') of the amorphous polyester resin was G'(70°C) = 1,568,900 Pa, G'(100°C) = 1,990 Pa.

[0160] <Amorphous polyester dispersion P4> A resin solution was prepared by dissolving 25 parts of amorphous polyester resin C in 75 parts of methyl ethyl ketone (MEK), adding 22.7 g of a 5% aqueous ammonia solution, and stirring uniformly with a stirrer. Next, 100 parts of demineralized water was placed in a round-bottom flask, and the prepared resin solution was further added thereto, followed by dispersion with a homogenizer (T25 model, manufactured by IKA) at a rotation speed of 8,000 rpm for 10 minutes. The solvent was then removed by vacuum distillation at 80°C using an aspirator, yielding amorphous polyester dispersion P4. The median diameter (D50) of the primary polymer particles of the amorphous polyester resin particles in amorphous polyester dispersion P4 was measured using a Nanotrac analyzer and found to be 200 nm. The storage modulus (G') of the amorphous polyester resin was G'(70°C) = 751,970 Pa, G'(100°C) = 709 Pa.

[0161] <Amorphous polyester dispersion P5> A resin solution was prepared by dissolving 25 parts of amorphous polyester resin D in 75 parts of methyl ethyl ketone (MEK), adding 24.6 g of a 5% aqueous ammonia solution, and stirring uniformly with a stirrer. Next, 100 parts of demineralized water was placed in a round-bottom flask, and the prepared resin solution was further added thereto, followed by dispersion with a homogenizer (T25 model, manufactured by IKA) at a rotation speed of 8,000 rpm for 10 minutes. The solvent was then removed by vacuum distillation at 80°C using an aspirator, yielding Amorphous Polyester Dispersion P5. The median diameter (D50) of the primary polymer particles of the amorphous polyester resin particles in Amorphous Polyester Dispersion P5 was measured using a Nanotrac analyzer and found to be 212 nm. The storage modulus (G') of the amorphous polyester resin was G'(70°C) = 601120 Pa, G'(100°C) = 1632 Pa.

[0162] <Amorphous polyester dispersion P6> 25 parts of amorphous polyester resin A was dissolved in 75 parts of methyl ethyl ketone (MEK), and 22.7 g of a 5% aqueous ammonia solution was added thereto, followed by stirring uniformly with a stirrer to prepare a resin solution. Next, 100 parts of demineralized water was placed in a round-bottom flask, and the prepared resin solution was further added thereto, followed by dispersion with a homogenizer (T25 model, manufactured by IKA) at a rotation speed of 8,000 rpm for 10 minutes. The solvent was then removed by vacuum distillation at 80°C using an aspirator, yielding Amorphous Polyester Dispersion P6. The median diameter (D50) of the primary polymer particles of the amorphous polyester resin particles in Amorphous Polyester Dispersion P5 was measured using a Nanotrac analyzer and found to be 180 nm. The storage modulus (G') of the amorphous polyester resin was G'(70°C) = 31,750,000 Pa, G'(100°C) = 5,317 Pa.

[0163] <Amorphous polyester dispersion P7> 25 parts of amorphous polyester resin B was dissolved in 75 parts of methyl ethyl ketone (MEK), and 17.0 g of a 5% aqueous ammonia solution was added thereto, followed by stirring uniformly with a stirrer to prepare a resin solution. Next, 100 parts of demineralized water was placed in a round-bottom flask, and the prepared resin solution was further added thereto, followed by dispersion with a homogenizer (T25 model, manufactured by IKA) at a rotation speed of 8,000 rpm for 10 minutes. The solvent was then removed by vacuum distillation at 80°C using an aspirator, yielding Amorphous Polyester Dispersion P3. The median diameter (D50) of the primary polymer particles of the amorphous polyester resin particles in Amorphous Polyester Dispersion P5 was measured using a Nanotrac analyzer and found to be 190 nm. The storage modulus (G') of the amorphous polyester resin was G'(70°C) = 336110 Pa, G'(100°C) = 427 Pa.

[0164] [Example 1] Toner C1 was prepared as follows.

[0165] A mixer equipped with a stirrer, a heating / cooling device, and a device for charging raw materials and auxiliary agents was charged with 90.0 parts (solids) of styrene acrylic dispersion A1, 0.17 parts (solids) of 20% DBS aqueous solution, 0.56 parts (solids) of 5% iron(II) sulfate heptahydrate aqueous solution, and 4.4 parts (solids) of colorant dispersion G1, in that order, while stirring. The internal temperature was raised to 39.0°C over 60 minutes, and then to 42.0°C over 180 minutes. Next, a mixture of 10.0 parts (solids) of Amorphous Polyester Dispersion P1 and 0.3 parts of a 20% DBS aqueous solution (solids (amount equivalent to 2 parts per 100 parts of amorphous polyester)) was added dropwise over 30 minutes. 30 minutes after the dropwise addition was completed, the pH of the system was adjusted to 8.3 using a 4.8% potassium hydroxide aqueous solution, and 6.0 parts (solids) of a 20% DBS aqueous solution and 232.4 parts of deionized water were added. The mixture was then heated to 65°C over 90 minutes, and then to 73°C over 60 minutes. It was then cooled to 30°C over 30 minutes.

[0166] The resulting dispersion was extracted and filtered using a No. 5C filter paper manufactured by Toyo Roshi Kaisha, Ltd., under suction with an aspirator. The cake remaining on the filter paper was transferred to a stainless steel container equipped with a stirrer (propeller blade), and ion-exchanged water with an electrical conductivity of 1 μS / cm was added and stirred to uniformly disperse the mixture. This process was repeated until the electrical conductivity of the filtrate reached 2 μS / cm. The resulting cake was then dried for 48 hours in a fan dryer set at 40°C, yielding toner base particles B1.

[0167] Toner base particles B1 (100 parts) prepared in this way, polymer / silica composite particles ATLAS100 (manufactured by Cabot Corporation, silica / polymer ratio = 70 / 30, true specific gravity = 1.7 g / cm 3 4 parts of titania / silica composite oxide particles STX50.1 (manufactured by Nippon Aerosil Co., Ltd.), 0.5 parts of small particle silica RY200L (manufactured by Nippon Aerosil Co., Ltd.), and 0.4 parts of small particle silica RY200L (manufactured by Nippon Aerosil Co., Ltd.) were added, and the mixture was stirred and mixed in a Henschel mixer at 3000 rpm for 15 minutes, and then sieved to obtain toner C1. The core / shell structure of this toner C1 is as shown in Table 3. The volume median particle diameter, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C1 were measured. The results are shown in Table 2.

[0168] [Example 2] Toner C2 was prepared in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A2. The core / shell structure of this toner C2 is as shown in Table 3. The volume median particle size, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C2 were measured. The results are shown in Table 2.

[0169] [Example 3] Toner C3 was prepared in the same manner as toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A2 and amorphous polyester dispersion P1 was replaced with amorphous polyester dispersion P2. The core / shell structure of this toner C3 is as shown in Table 3. The volume median particle size, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C3 were measured. The results are shown in Table 2.

[0170] [Example 4] Toner C4 was prepared in the same manner as toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A2 and amorphous polyester dispersion P1 was replaced with amorphous polyester dispersion P3. The core / shell structure of this toner C4 is as shown in Table 3. The volume median particle size, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C4 were measured. The results are shown in Table 2.

[0171] [Example 5] Toner C5 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with 95.0 parts (solid content) of styrene acrylic dispersion A3 and amorphous polyester dispersion P1 was replaced with 5.0 parts (solid content) of amorphous polyester dispersion P4. The core / shell structure of this toner C5 is as shown in Table 3. The volume median particle size, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C5 were measured. The results are shown in Table 2.

[0172] [Example 6] Toner C6 was prepared in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with 95.0 parts (solid content) of styrene acrylic dispersion A3 and amorphous polyester dispersion P1 was replaced with 5.0 parts (solid content) of amorphous polyester dispersion P5. The core / shell structure of this toner C6 is as shown in Table 3. The volume median particle size, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C6 were measured. The results are shown in Table 2.

[0173] [Comparative Example 1] Toner C7 was prepared as follows.

[0174] A mixer equipped with a stirrer, a heating / cooling device, and a device for charging raw materials and auxiliary agents was charged with 85.0 parts (solids) of styrene acrylic dispersion A4, 0.17 parts (solids) of 20% DBS aqueous solution, 0.56 parts (solids) of 5% iron(II) sulfate heptahydrate aqueous solution, and 4.4 parts (solids) of colorant dispersion G1, in that order, while stirring. The internal temperature was raised to 41.0°C over 60 minutes, and then to 45.0°C over 180 minutes. Next, 15.0 parts (solids) of Styrene Acrylic Dispersion A5 was added dropwise over 30 minutes. After 30 minutes, 4.0 parts (solids) of a 20% DBS aqueous solution and 23 parts of deionized water were added, and the mixture was heated to 80°C over 90 minutes, then to 83°C over 60 minutes, and then cooled to 30°C over 30 minutes.

[0175] The resulting dispersion was extracted and filtered using a No. 5C filter paper manufactured by Toyo Roshi Kaisha, Ltd., under suction with an aspirator. The cake remaining on the filter paper was transferred to a stainless steel container equipped with a stirrer (propeller blade), and ion-exchanged water with an electrical conductivity of 1 μS / cm was added and stirred to uniformly disperse the mixture. This process was repeated until the electrical conductivity of the filtrate reached 2 μS / cm. The resulting cake was then dried for 48 hours in a fan dryer set at 40°C, yielding toner base particles B7.

[0176] Toner base particles B7 (100 parts) prepared in this way, polymer / silica composite particles ATLAS100 (manufactured by Cabot Corporation, silica / polymer ratio = 70 / 30, true specific gravity = 1.7 g / cm 3 4 parts of titania / silica composite oxide particles STX50.1 (manufactured by Nippon Aerosil Co., Ltd.), 0.5 parts of small particle silica RY200L (manufactured by Nippon Aerosil Co., Ltd.), and 0.4 parts of small particle silica RY200L (manufactured by Nippon Aerosil Co., Ltd.) were added, and the mixture was stirred and mixed in a Henschel mixer at 3000 rpm for 15 minutes, and then sieved to obtain toner C7. The core / shell structure of this toner C7 is as shown in Table 3. The volume median particle size, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C7 were measured. The results are shown in Table 2.

[0177] Comparative Example 2 Toner C8 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with 95.0 parts (solid content) of styrene acrylic dispersion A3 and amorphous polyester dispersion P1 was replaced with 5.0 parts (solid content) of amorphous polyester dispersion P6. The core / shell structure of this toner C8 is as shown in Table 3. The volume median particle size, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C8 were measured. The results are shown in Table 2.

[0178] Comparative Example 3 Toner C9 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with 85.0 parts (solid content) of styrene acrylic dispersion A2 and amorphous polyester dispersion P1 was replaced with 15.0 parts (solid content) of amorphous polyester dispersion P6. The core / shell structure of this toner C9 is as shown in Table 3. The volume median particle size, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C9 were measured. The results are shown in Table 2.

[0179] Comparative Example 4 Toner C10 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with 90.0 parts (solid content) of styrene acrylic dispersion A2 and amorphous polyester dispersion P1 was replaced with 10.0 parts (solid content) of amorphous polyester dispersion P7. The core / shell structure of this toner C10 is as shown in Table 3. The volume median particle diameter, average circularity, and percentage of particles having a particle size of 1.0 μm or less of the obtained toner C10 were measured. The results are shown in Table 2.

[0180] [Table 2]

[0181] <Adhesion evaluation (scraping test)> The obtained toner was applied to a PET-coated glossy recording paper (water-resistant paper Kareka, manufactured by Kokusai Pulp & Paper Co., Ltd.) with a deposition amount of approximately 0.8 mg / cm using two toner cartridges in a commercially available printer with a printing speed of 16 ppm, a non-magnetic single-component developer rubber roller, a metal blade, and an organic photoreceptor charged by a charging roller (PCR), and the fixing unit removed. 2 An unfixed toner image was printed. The heat roll fixing machine used had a roller diameter of 27 mm, a nip width of 9 mm, and a fixing speed of 95 mm / sec. The upper roller had a heater, the roller surface was made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), and no silicone oil was applied. The roller surface temperature was set to 175°C, and the adhesion amount was approximately 0.8 mg / cm 2 The recording paper bearing the unfixed toner image was transported to the fixing nip section, and a fixed image was obtained. An abrasion test was performed by scraping the fixed image with a vertically placed flathead screwdriver. The tip of the flathead screwdriver had a width of 1 mm, and a weight of 250 g was applied to the tip. The distance traveled was 2 cm, and a total of three back-and-forth scraping tests were performed. The speed of travel was approximately 1 cm / s, and the angle between the direction of travel and the tip of the flathead screwdriver was 90°. The degree of abrasion was visually observed and evaluated according to the following criteria. The evaluation results are shown in Table 4. (Evaluation criteria) ◎: Could not remove at all. ○: There was one or less small white dot formed by scraping. △: The length of the scraped line was less than 3 mm, or there were multiple small white dots. ×: The length of the scraped line was 3 mm or more.

[0182] <Low temperature fixability evaluation> The obtained toner was applied to recording paper (OKI Excellent White (product name)) at a toner adhesion rate of approximately 0.5 mg / cm using a commercially available printer with a printing speed of 16 ppm, a non-magnetic single-component developing rubber roller, a metal blade, and an organic photoreceptor charged by a charging roller (PCR), and the fixing unit removed. 2 An unfixed toner image was printed. The thermal roll fixing machine used had a roller diameter of 27 mm, a nip width of 9 mm, a heater on the upper roller, and a roller surface made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) without silicone oil coating. The roller surface temperatures were set to 130°C, 135°C, 140°C, and 145°C, and fixing was performed at each temperature at a fixing speed of 229 mm / sec to prepare evaluation samples. The evaluation criteria for the fixing test were as follows. The evaluation results are shown in Table 4. (Evaluation criteria) ◯: The fixed image did not offset, and no image defects occurred even when rubbed. △: The fixed image did not offset, but image defects occurred when rubbed. x: The fixed image was offset.

[0183] <Storage stability evaluation> A metal cylinder with a diameter of 2 cm was placed upright on a metal plate, and a medical paper was wrapped around the inside of the cylinder. 10 g of toner was gently poured into the vertically placed metal cylinder to fill it, and then a 20 g weight was placed on top of the toner. The metal cylinder was placed on the metal plate and placed in a thermo-hygrostat at a temperature of 50°C and a relative humidity of 55% (normal humidity conditions) for 48 hours, or in a high-temperature, high-humidity chamber at a temperature of 50°C and a relative humidity of 80% (high humidity conditions) for 24 hours. After removing the sample from the thermo-hygrostat, the metal cylinder and wrapping paper were gently removed, and the toner that had solidified into a cylindrical shape was removed while still in the upright position. Loads were applied in 10g increments to the toner particles in a vertically placed, fixed state, and the load at which the cylindrical shape collapsed was measured. The load measurements were evaluated according to the following criteria. The evaluation results are shown in Table 4. (Evaluation criteria) ◯: Collapsed under a load of 500 g or less. This means that the toner adhesion was weak and the storage stability was good. △: It did not collapse under a load of 500 g, but collapsed under a load of 1500 g or less. x: No collapse under a load of 1500 g. This means that the toner adhered strongly and the storage stability was poor.

[0184] [Table 3]

[0185] [Table 4]

[0186] <Consideration> From the above examples and comparative examples, it was found that by using a styrene acrylic resin as the binder resin for the core and an amorphous polyester resin having a storage modulus in an appropriate range as the binder resin for the shell, the toner has excellent adhesion to printing media such as PET-coated paper and low-temperature fixability, and does not cause deterioration of storage stability under high humidity conditions.

Claims

1. A toner having a core-shell structure, the core and the shell each contain a binder resin, the binder resin of the core contains a styrene acrylic resin, the binder resin of the shell contains an amorphous polyester resin, the binder resin of the shell has a storage modulus at 70°C (G'(70°C)) of 500,000 Pa or more and a storage modulus at 100°C (G'(100°C)) of 5,000 Pa or less when measured with a rheometer; The toner, wherein the glass transition temperature of the amorphous polyester resin is 50°C or higher and 57°C or lower.

2. 2. The toner according to claim 1, wherein the binder resin of the core is a styrene acrylic resin, and the binder resin of the shell is an amorphous polyester resin.

3. 3. The toner according to claim 1, wherein the content of the amorphous polyester resin is 3% by mass or more and 40% by mass or less with respect to the total mass of the toner.

4. 4. The toner according to claim 1, wherein the toner contains a wax, and the content of the wax in the toner is 5% by mass or more and 30% by mass or less.

5. 5. The toner according to claim 1, wherein the amorphous polyester resin has a softening temperature of 90 to 150°C.

6. 6. The toner according to claim 1, wherein the acid value of the amorphous polyester resin is 6 mgKOH / g or more and 20 mgKOH / g or less.

7. The ratio of the acid values ​​of the styrene-acrylic resin and the amorphous polyester resin ([acid value of the styrene-acrylic resin of the core] / [acid value of the amorphous polyester resin of the shell]) is The toner according to any one of claims 1 to 6, wherein the viscosity is 0.85 or more and 2.9 or less.

8. A toner cartridge containing the toner according to any one of claims 1 to 7.

9. An image forming apparatus containing the toner according to any one of claims 1 to 7.

Images