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

Abstract

An electrostatic charge image developing toner, an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, and a method, the electrostatic charge image developing toner having toner particles including a binder resin, a release agent, and resin particles forming domains inside the toner particles, the binder resin including a polyester resin, the average ester group concentration (c1) of the binder resin is 25-48% by mass (inclusive), and when the ester group concentration of the resin particles is c2, the value of c2 / c1 is 0.30-0.70 (inclusive).

Description

TECHNICAL FIELD

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

[0002] In Patent Literature 1, there is disclosed a method for producing a toner (Z) containing a colorant, a crystalline resin (A), and a vinyl resin (B) having an ester group, the method being characterized by comprising a step of first heating a coagulum (Y) obtained by coagulating a dispersion (X) in a dispersion liquid (W) containing a colorant, a crystalline resin (A), and a vinyl resin (B) to fuse the coagulum, thereby obtaining resin particles (Z'), the vinyl resin (B) including a resin (LB) having at least one peak in a region of a molecular weight of 3,000 to 60,000 in a molecular weight distribution obtained by gel permeation chromatography, the ester group concentration of the vinyl resin (B) being 14 to 55% by weight based on the weight of (B), and the content rate of the vinyl resin (B) being 50 to 90% by weight based on the weight of the toner (Z).

[0003] In Patent Literature 2, there is disclosed a toner for electrostatic image development, having: toner particles containing a polyester resin composed of a polycondensate of a polycarboxylic acid and a polyol, the polyol containing ethylene glycol at a mass ratio of 40 mass% or more and 90 mass% or less with respect to the mass of all the polyols; and an external additive containing silica particles having a product of a volume average particle diameter D50 (pm) and a BET specific surface area SA (m 2 / g) of 1.4 x 10 3 or more and 5.0 x 10 3 or less.

[0004] In Patent Literature 3, there is disclosed a toner for electrostatic latent image development, which is a toner containing a plurality of toner particles, the toner particles having a sea domain and a plurality of island domains distributed in island shapes with respect to the sea domain, the sea domain being substantially composed of a plurality of resins containing at least a polyester resin containing an alcohol component having 2 or more and 6 or less carbon atoms, the island domains being substantially composed of a resin containing an aniline black dye, a dispersed diameter of the island domains being 0.1 pm or more and 1.0 pm or less, the sea domain containing the polyester resin containing the alcohol component having 2 or more and 6 or less carbon atoms at a proportion of 5 mass% or more and 50 mass% or less with respect to the total amount of the plurality of resins, a ratio of an SP value of the resins constituting the sea domain with respect to an SP value of the resins constituting the island domains being 0.98 or less or 1.20 or more.

[0005] Disclosed in Patent Literature 4 is a toner for electrostatic latent image development, which contains a binder resin, a colorant, and a releasing agent, the toner for electrostatic latent image development being characterized by containing less than 3% by mass of a styrene copolymer having a weight average molecular weight (Mw) in the range of 70,000 to 300,000 and an acid value (AV) in the range of 70 mgKOH / g to 220 mgKOH / g.

[0006] Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 2019-74761

[0007] Patent Literature 2: Japanese Patent Application Laid-Open (JP-A) No. 2018-163200

[0008] Patent Literature 3: Japanese Patent Application Laid-Open (JP-A) No. 2017-142409

[0009] Patent Literature 4: Japanese Patent Application Laid-Open (JP-A) No. 2008-15023 SUMMARY

[0010] The present application provides a toner for electrostatic image development, which has toner particles containing a binder resin, a releasing agent, and resin particles formed in a domain inside the toner particles, the binder resin containing a polyester resin, an average ester group concentration cl of the binder resin being 25% by mass or more and 48% by mass or less, or in the case where an ester group concentration of the resin particles is set as c2, a value of c2 / cl being less than 0.30 or more than 0.70, the concentration unevenness inhibitory property in a high humidity environment (25°C 80% RH) being excellent.

[0011] Specific means for solving the above-described problems include the following modes.

[0012] <1> A toner for electrostatic image development, which has toner particles containing a binder resin, a releasing agent, and resin particles formed in a domain inside the toner particles, the binder resin containing a polyester resin, an average ester group concentration cl of the binder resin being 25% by mass or more and 48% by mass or less, or in the case where an ester group concentration of the resin particles is set as c2, a value of c2 / cl being 0.30 or more and 0.70 or less.

[0013] <2> The toner for electrostatic image development according to <1>, wherein

[0014] The content of the releasing agent is 1% by mass or more and 10% by mass or less with respect to the total mass of the toner particles.

[0015] <3> The toner for electrostatic image development according to <1> or <2>, wherein

[0016] When the content of the release agent in the toner particles is set as Ww and the content of the resin particles is set as Wb, the value of Wb / Ww is 0.3 or more and 5.0 or less.

[0017] <4> The electrostatic image developing toner according to any one of <1> to <3>, wherein

[0018] The average circle-equivalent diameter of the domains formed by the resin particles is 50 nm or more and 300 nm or less.

[0019] <5> The electrostatic image developing toner according to any one of <1> to <4>, wherein

[0020] The melting point of the release agent is 60°C or more and 120°C or less.

[0021] <6> The electrostatic image developing toner according to any one of <1> to <5>, wherein

[0022] The resin particles are styrene (meth)acrylic resin particles.

[0023] <7> The electrostatic image developing toner according to any one of <1> to <6>, wherein

[0024] The resin particles are crosslinked resin particles.

[0025] <8> The electrostatic image developing toner according to any one of <1> to <7>, wherein

[0026] The tetrahydrofuran-insoluble component of the resin particles is 80 mass% or more.

[0027] <9> The electrostatic image developing toner according to any one of <1> to <8>, wherein

[0028] The release agent contains at least one selected from the group including hydrocarbon waxes and ester waxes.

[0029] <10> The electrostatic image developing toner according to any one of <1> to <9>, wherein

[0030] The ester group concentration c3 of the release agent is 15 mass% or less.

[0031] <11> An electrostatic image developer containing the electrostatic image developing toner according to any one of <1> to <10>.

[0032] <12> A toner cartridge containing the electrostatic image developing toner according to any one of <1> to <10>, and detachable to an image forming apparatus.

[0033] A process cartridge including a developing device according to <11>, the process cartridge accommodating the electrostatic image developer and developing an electrostatic image formed on a surface of an image holding member into a toner image using the electrostatic image developer, the process cartridge being detachably attached to an image forming apparatus.

[0034] An image forming apparatus including: an image holding member; a charging device charging a surface of the image holding member; an electrostatic image forming device forming an electrostatic image on the surface of the image holding member that has been charged; a developing device according to <11> accommodating the electrostatic image developer and developing an electrostatic image formed on the surface of the image holding member into a toner image using the electrostatic image developer; a transfer device transferring the toner image formed on the surface of the image holding member onto a surface of a recording medium; and a fixing device fixing the toner image that has been transferred onto the surface of the recording medium.

[0035] An image forming method including: a charging step of charging a surface of an image holding member; an electrostatic image forming step of forming an electrostatic image on the surface of the image holding member that has been charged; a developing step of developing an electrostatic image formed on the surface of the image holding member into a toner image using the electrostatic image developer according to <11>; a transfer step of transferring the toner image formed on the surface of the image holding member onto a surface of a recording medium; and a fixing step of fixing the toner image that has been transferred onto the surface of the recording medium.

[0036] Effects of Invention

[0037] According to the invention according to <1> or <9>, there is provided an electrostatic image developing toner in which, in comparison with a case where a toner particle including a binder resin including a polyester resin, a releasing agent, and a resin particle forming a domain inside the toner particle, an average ester group concentration cl of the binder resin is less than 25% by mass or more than 48% by mass, or in a case where an ester group concentration of the resin particle is set to c2, a value of c2 / cl is less than 0.30 or more than 0.70, concentration unevenness inhibition in a high-humidity environment is excellent.

[0038] According to the invention according to <2>, there is provided an electrostatic image developing toner in which, in comparison with a case where a content of the releasing agent is less than 1% by mass or more than 10% by mass with respect to a total mass of the toner particle, concentration unevenness inhibition in a high-humidity environment is more excellent.

[0039] According to the invention according to <3>, there is provided an electrostatic image developing toner in which, compared to a case where Wb / Ww is less than 0.3 or more than 5.0 when a content of the releasing agent in the toner particle is set as Ww and a content of the resin particle is set as Wb, concentration unevenness inhibition in a high-humidity environment is more excellent.

[0040] According to the invention according to <4>, there is provided an electrostatic image developing toner in which, compared to a case where an average circle-equivalent diameter of a domain formed of the resin particle is less than 50 nm or more than 300 nm, concentration unevenness inhibition in a high-humidity environment is more excellent.

[0041] According to the invention according to <5>, there is provided an electrostatic image developing toner in which, compared to a case where a melting point of the releasing agent is less than 60°C or more than 120°C, concentration unevenness inhibition in a high-humidity environment is more excellent.

[0042] According to the invention according to <6>, there is provided an electrostatic image developing toner in which, compared to a case where the resin particle is a polyester resin particle, concentration unevenness inhibition in a high-humidity environment is more excellent.

[0043] According to the invention according to <7>, there is provided an electrostatic image developing toner in which, compared to a case where the resin particle is a resin particle not having a crosslinked structure, concentration unevenness inhibition in a high-humidity environment is more excellent.

[0044] According to the invention according to <8>, there is provided an electrostatic image developing toner in which, compared to a case where a tetrahydrofuran-insoluble component of the resin particle is less than 80 mass%, concentration unevenness inhibition in a high-humidity environment is more excellent.

[0045] According to the invention according to <10>, there is provided an electrostatic image developing toner in which, compared to a case where an ester group concentration c3 of the releasing agent is more than 15 mass%, concentration unevenness inhibition in a high-humidity environment is more excellent.

[0046] According to the invention according to <11>, <12>, <13>, <14>, or <15>, there is provided an electrostatic image developing agent, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method in which, compared to a case where a toner particle having a toner particle including a binder resin, a releasing agent, and a resin particle forming a domain inside the toner particle is used, the binder resin includes a polyester resin, an average ester group concentration c1 of the binder resin is less than 25 mass% or more than 48 mass%, or when an ester group concentration of the resin particle is set as c2, a value of c2 / c1 is less than 0.30 or more than 0.70, concentration unevenness inhibition in a high-humidity environment is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0047] An embodiment of the present application will be described in detail below with reference to the following drawings.

[0048] Figure 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment;

[0049] Figure 2 is a schematic configuration diagram of a process cartridge according to the present embodiment.

[0050] Explanation of symbols

[0051] 1Y, 1M, 1C, 1K - photoreceptor (example of image holding body), 2Y, 2M, 2C, 2K - charging roller (example of charging device), 3 - exposure device (example of electrostatic image forming device), 3Y, 3M, 3C, 3K - laser beam, 4Y, 4M, 4C, 4K - developing device (example of developing device), 5Y, 5M, 5C, 5K - primary transfer roller (example of primary transfer device), 6Y, 6M, 6C, 6K - photoreceptor cleaning device (example of cleaning device), 8Y, 8M, 8C, 8K - toner cartridge, 10Y, 10M, 10C, 10K - image forming unit, 20 - intermediate transfer belt (example of intermediate transfer body), 22 - drive roller, 24 - support roller, 26 - secondary transfer roller (example of secondary transfer device), 28 - fixing device (example of fixing device), 30 - intermediate transfer body cleaning device, 107 - photoreceptor (example of image holding body), 108 - charging roller (example of charging device), 109 - exposure device (example of electrostatic image forming device), 111 - developing device (example of developing device), 112 - transfer device (example of transfer device), 113 - photoreceptor cleaning device (example of cleaning device), 115 - fixing device (example of fixing device), 116 - mounting rail, 118 - opening for exposure, 117 - housing, 200 - process cartridge, 300 - recording paper (example of recording medium), P - recording paper (example of recording medium). DETAILED DESCRIPTION

[0052] Hereinafter, an embodiment of the present application will be described. The description and examples thereof exemplify the embodiment, and do not limit the scope of the embodiment.

[0053] In the present embodiment, a numerical range indicated by "~" indicates a range including the values written before and after the "~" as the minimum value and the maximum value, respectively.

[0054] In the numerical range described in stages in the present embodiment, the upper limit value or the lower limit value described in one numerical range can be replaced with the upper limit value or the lower limit value of another numerical range described in stages. Also, in the numerical range described in the present embodiment, the upper limit value or the lower limit value of the numerical range can be replaced with the value shown in the examples.

[0055] In the present embodiment, the term "step" includes not only a single step, but also a case where the step cannot be clearly distinguished from other steps, as long as the purpose of the step is achieved.

[0056] In the present embodiment, each component can include a plurality of corresponding substances. In the present embodiment, when a plurality of substances corresponding to each component is present in the composition, the total amount of the plurality of substances present in the composition is meant unless specifically specified.

[0057] In the present embodiment, a plurality of particles corresponding to each component can be included. When a plurality of particles corresponding to each component is present in the composition, the particle diameter of each component is meant with respect to the mixture of the plurality of particles present in the composition unless specifically specified.

[0058] In the present embodiment, "(meth)acrylic acid" is a term including both acrylic acid and methacrylic acid, and "(meth)acrylate" is a term including both acrylate and methacrylate.

[0059] In the present embodiment, the "toner for electrostatic image development" is also referred to as "toner".

[0060] (Toner for electrostatic image development)

[0061] The toner for electrostatic image development according to the present embodiment has toner particles including a binder resin, a releasing agent, and a resin particle forming a domain inside the toner particle, the binder resin including a polyester resin, the average ester group concentration cl of the binder resin being 25% by mass or more and 48% by mass or less, and when the ester group concentration of the resin particle is c2, the value of c2 / cl being 0.30 or more and 0.70 or less.

[0062] In printing in a high-humidity environment, the conventional toner sometimes loses heat to moisture in paper due to moisture absorption of paper, thereby causing fixing failure and the like. In response to this, by controlling the moisture absorption of the binder resin, it is possible to improve the fixing property, but on the other hand, the binder resin is easily softened, and therefore the releasing agent sometimes excessively exudes on the surface of the particle, thereby causing unevenness in the concentration of the image due to the shift of the releasing agent.

[0063] In the electrostatic image developing tone agent according to this embodiment, the average ester concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less, and when the ester concentration of the resin particles is set as c2, the value of c2 / c1 is 0.30 or more and 0.70 or less, as estimated below. First, appropriate plasticization under high humidity conditions can ensure fixing performance on hygroscopic paper. Moreover, when the binder resin begins to melt, the resin particles tend to aggregate, and at this time, they aggregate by penetrating the aggregates with wax, thus suppressing the growth of the release agent. As a result, the amount of release agent exudation is stable regardless of humidity, and uneven image concentration can be suppressed even under high humidity conditions.

[0064] The composition of the toner for electrostatic image development according to this embodiment will be described in detail below.

[0065] [Toning agent particles]

[0066] Colorant particles comprise binding resin and resin particles, and may include colorants, release agents and other additives as needed.

[0067] <Ester concentration>

[0068] In the electrostatic image developing tone agent according to this embodiment, the average ester concentration c1 of the bonding resin is 25% by mass or more and 48% by mass or less, and when the ester concentration of the resin particles is set to c2, the value of c2 / c1 is 0.30 or more and 0.70 or less.

[0069] From the viewpoint of suppressing concentration inhomogeneity under high humidity conditions, the average ester concentration c1 of the adhesive resin is preferably 28% by mass or more and 47% by mass or less, more preferably 30% by mass or more and 45% by mass or less, and especially preferably 35% by mass or more and 43% by mass or less.

[0070] From the viewpoint of suppressing uneven concentration under high humidity conditions, the value of c2 / c1 is preferably 0.32 or more and 0.68 or less, more preferably 0.35 or more and 0.65 or less, and especially preferably 0.40 or more and 0.60 or less.

[0071] From the viewpoint of suppressing concentration non-uniformity under high humidity conditions, the ester group concentration c2 of the resin particles is preferably 7% by mass or more and 30% by mass or less, more preferably 10% by mass or more and 25% by mass or less, and especially preferably 12% by mass or more and 21% by mass or less.

[0072] From the viewpoint of further enhancing the effect of this embodiment, the ester concentration c3 of the release agent is preferably, for example, 15% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, and particularly preferably 0% by mass.

[0073] The ester concentration can be calculated based on the number of ester groups [-C(=O)O-] in the resin or compound, specifically, by the following formula.

[0074] Ester concentration (mass%) = (N × 44) / number average molecular weight × 100

[0075] Where N is the average number of ester groups per molecule, and 44 is the formula weight of the ester group [-C(=O)O-].

[0076] The chemical structure of a resin or compound is calculated by determining the monomer composition or chemical structure and the number of ester groups using methods such as nuclear magnetic resonance spectroscopy (NMR).

[0077] <Resin Particles>

[0078] The colorant particles are resin particles that form internal domains within the colorant particles.

[0079] Examples of resin particles that can be added to polyolefin resins (polyethylene, polypropylene, etc.), styrene resins (polystyrene, poly(α-methylstyrene), etc.), (meth)acrylic resins (polymethyl methacrylate, polyacrylonitrile, etc.), epoxy resins, polyurethane resins, polyurea resins, polyamide resins, polycarbonate resins, polyether resins, polyester resins and their copolymers are examples of resin particles.

[0080] From the viewpoint of suppressing uneven concentration in high humidity environments, styrene-(meth)acrylic resin particles are preferred, for example.

[0081] -Average circular equivalent diameter of the domain formed by resin particles-

[0082] From the viewpoint of suppressing concentration non-uniformity under high humidity conditions, the average circular equivalent diameter of the domain formed by the resin particles is preferably 50 nm or more and 300 nm or less, more preferably 100 nm or more and 250 nm or less, and especially preferably 120 nm or more and 190 nm or less.

[0083] The average circular equivalent diameter of the domain formed by the resin particles is the value measured using a transmission electron microscope (TEM).

[0084] As a transmission electron microscope, for example, the JEM-2100plus manufactured by JEOL Ltd. can be used.

[0085] Specifically, the method for determining the average circular equivalent diameter of the domain formed by resin particles is as follows.

[0086] The toner particles were mixed with epoxy resin to embed them, and the epoxy resin was then cured. The cured material was cut into sections approximately 0.1 μm thick using a slicing machine. The obtained thin sections were stained with ruthenium tetroxide in a desiccator at 30°C. The stained thin sections were photographed at 10,000x magnification using a transmission electron microscope. For 100 resin-added particles dispersed in the toner particles, their circumferential equivalent diameters were calculated based on their respective cross-sectional areas, and the arithmetic mean of these values ​​was taken as the average circumferential equivalent diameter.

[0087] -Insoluble components of tetrahydrofuran-

[0088] From the viewpoint of suppressing uneven concentration under high humidity conditions, the tetrahydrofuran insoluble content of the resin particles is preferably 80% by mass or more, more preferably 85% by mass or more, and especially preferably 90% by mass or more.

[0089] The method for determining the THF insoluble component in this embodiment is described.

[0090] (1) Weigh 0.25g of the sample, add 40mL of tetrahydrofuran to it, and mix and stir for 3 hours.

[0091] (2) Then, the mixture obtained in (1) was separated for 30 minutes using a centrifuge at 2,000 rpm (revolutions per minute).

[0092] (3) Weigh 5 mL of the supernatant obtained in (2) after centrifugation and transfer it to an aluminum tray. Then, evaporate and dry the tetrahydrofuran in a vacuum dryer with the temperature adjusted to 50°C.

[0093] (4) The THF insoluble component is calculated based on the difference in mass of the aluminum disc before and after drying using the following formula.

[0094] THF insoluble component [%] = {0.25 - [(mass of supernatant and aluminum disc) - (mass of dried aluminum disc)] × 8} / 0.25 × 100

[0095] Monomer composition of styrene-(meth)acrylic resin particles-

[0096] Examples of styrene-(meth)acrylic resin particles in this embodiment include resin particles formed by polymerizing styrene monomers and (meth)acrylic ester monomers, etc., through free radical polymerization.

[0097] Examples of styrene monomers include styrene, α-methylstyrene, vinylnaphthalene, or alkyl-substituted styrene with alkyl chains such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene; halogen-substituted styrene such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene; and fluorinated styrene such as 4-fluorostyrene and 2,5-difluorostyrene. Styrene or α-methylstyrene is preferred, for example.

[0098] Examples of (meth)acrylate monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, n-decyl methacrylate, n-dodecyl methacrylate, n-lauryl methacrylate, n-tetradecyl methacrylate, n-hexadecyl methacrylate, n-octadecyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, and isopentyl methacrylate. Esters, amyl methacrylate, neopentyl methacrylate, isohexyl methacrylate, isohexyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, biphenyl methacrylate, diphenyl methacrylate, tert-butylphenyl methacrylate, tert-phenyl methacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methoxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-carboxyethyl methacrylate, etc.

[0099] From the viewpoint of ease of adjusting the ester group concentration of styrene-(meth)acrylate resin, (meth)acrylate compounds having alkyl groups with 2 to 12 carbon atoms (also referred to as "carbon number") are preferred as monomers, (meth)acrylate compounds having alkyl groups with 2 to 10 carbon atoms are more preferred, and (meth)acrylate compounds having alkyl groups with 4 to 8 carbon atoms are particularly preferred.

[0100] Among them, n-butyl methacrylate, a monomer of styrene-(meth)acrylate resin, is particularly preferred as a (meth)acrylate monomer.

[0101] Furthermore, from the viewpoint of suppressing uneven concentration in high humidity environments, resin particles are preferably cross-linked resin particles, for example.

[0102] Examples of crosslinking agents that form crosslinked structures include aromatic polyfunctional vinyl compounds such as divinylbenzene and divinylnaphthalene; polyvinyl esters of aromatic polycarboxylic acids such as divinyl phthalate, divinyl isophthalate, divinyl terephthalate, divinyl phthalate, divinyl trimellitate, trivinyl trimellitate, divinyl naphthalene, and divinyl biphenylcarboxylate; divinyl esters of nitrogen-containing aromatic compounds such as divinyl pyridine dicarboxylate; vinyl esters of unsaturated heterocyclic carboxylic acids such as vinyl pyroviscose, vinyl furanate, vinyl pyrrole-2-carboxylate, and vinyl thiophene carboxylate; and vinyl esters of butanediol diacrylate, butanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, octanediol diacrylate, octanediol dimethacrylate, nonanediol diacrylate, nonanediol dimethacrylate, decanediol diacrylate, and decanediol dimethacrylate. (Meth)acrylates of straight-chain polyols such as acrylates, dodecanediol diacrylate, and dodecanediol dimethacrylate; (Meth)acrylates of branched and substituted polyols such as neopentyl glycol dimethacrylate, 2-hydroxyl, and 1,3-disacryloyloxypropane; polyethylene glycol di(meth)acrylate, polypropylene polyethylene glycol di(meth)acrylate, divinyl succinate, divinyl fumarate, vinyl maleate, divinyl maleate, etc. Divinyl alcohol, vinyl itaconic acid, vinyl itaconic acid, vinyl acetone dicarboxylic acid, vinyl glutarate, vinyl 3,3'-thiodipropionate, vinyl trans aconitate, vinyl trans aconitate, vinyl adipate, vinyl heptaate, vinyl octanoate, vinyl azelaate, vinyl sebacic acid, vinyl dodecanoate, vinyl tridecane, and other polyfunctional vinyl esters of polycarboxylic acids. Crosslinking agents can be used alone or in combination with two or more.

[0103] Among these, alkylene glycol diacrylates having 6 or more carbon atoms in their alkylene chains are preferred as crosslinking agents. That is, the resin particles preferably have structural units derived from alkylene glycol diacrylates, wherein the alkylene chains in the alkylene glycol diacrylates have 6 or more carbon atoms.

[0104] From the viewpoint of adjusting the crosslinking density within an appropriate range, the number of carbon atoms in the alkylene chain of the alkylene glycol diacrylate is preferably 6 or more, more preferably 6 or more and 12 or less, and even more preferably 8 or more and 12 or less. More specific examples of alkylene glycol diacrylates include 1,6-hexanediol acrylate, 1,6-hexanediol methacrylate, 1,8-octanediol diacrylate, 1,8-octanediol dimethacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, 1,12-dodecanediol diacrylate, and 1,12-dodecanediol dimethacrylate, with 1,10-decanediol diacrylate and 1,10-decanediol dimethacrylate being preferred.

[0105] The content of the crosslinking agent in the composition for forming resin particles is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, more preferably 0.2 parts by mass or more and 3.0 parts by mass or less, and even more preferably 0.3 parts by mass or more and 2.5 parts by mass or less, relative to 100 parts by mass of the monomers used.

[0106] From the viewpoint of suppressing uneven concentration under high humidity conditions, the content of resin particles relative to colorant particles is preferably 1% or more and 30% or less by mass, more preferably 3% or more and 25% or less by mass, and even more preferably 4% or more and 16% or less by mass.

[0107] <Mold Release Agent>

[0108] The colorant particles contain a release agent.

[0109] Examples of release agents include hydrocarbon waxes; natural waxes such as carnauba wax, rice bran wax, and candelilla wax; synthetic or mineral / petroleum-based waxes such as lignite wax; and ester waxes such as fatty acid esters and lignite esters. Release agents are not limited to these.

[0110] From the viewpoint of further enhancing the effects of this embodiment, it is preferable to include, for example, at least one selected from the group consisting of hydrocarbon waxes and ester waxes.

[0111] From the viewpoint of inhibiting uneven concentration under high humidity conditions, the melting point of the release agent is preferably 60°C or higher and 120°C or lower, more preferably 63°C or higher and 110°C or lower, and especially preferably 75°C or higher and 100°C or lower.

[0112] In addition, the melting point is determined based on the "melting peak temperature" described in JIS K 7121-1987 "Method for determination of the transformation temperature of plastics" using the DSC curve obtained by differential scanning calorimetry (DSC).

[0113] From the viewpoint of suppressing uneven concentration under high humidity conditions, the content of the release agent relative to the total mass of the colorant particles is preferably 1% by mass or more and 10% by mass or less, more preferably 2% by mass or more and 9% by mass or less, and especially preferably 3% by mass or more and 8% by mass or less.

[0114] Furthermore, when the content of the release agent in the colorant particles is set as Ww and the content of the resin particles is set as Wb, from the viewpoint of suppressing concentration non-uniformity under high humidity conditions, the value of Wb / Ww is preferably 0.3 or more and 5.0 or less, more preferably 0.5 or more and 4.0 or less, and particularly preferably more than 1.0 and 3.0 or less.

[0115] Furthermore, from the viewpoint of suppressing uneven concentration under high humidity conditions, the content of resin particles Wb in the colorant particles is preferably greater than the content of the release agent Ww.

[0116] <Adhesive Resin>

[0117] The colorant particles contain amorphous polyester resin as a binder resin.

[0118] Furthermore, the colorant particles may contain adhesive resins other than amorphous polyester resins.

[0119] Examples of adhesive resins include homopolymers of monomers such as styrene (e.g., styrene, p-chlorostyrene, α-methylstyrene, etc.), (meth)acrylates (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), olefinic unsaturated nitrile monomers (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropylene ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.) or copolymers of two or more of these monomers.

[0120] Examples of adhesive resins include epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, modified rosin, and other non-vinyl resins, mixtures of these with the vinyl resins, or graft polymers obtained by polymerizing vinyl monomers in the coexistence of these.

[0121] These adhesive resins can be used alone or in combination with two or more.

[0122] As the adhesive resin, polyester resin is preferred, for example.

[0123] Examples of polyester resins include, for instance, well-known amorphous polyester resins. Crystalline polyester resins can also be used in combination with amorphous polyester resins.

[0124] In addition, the "crystallization" of the resin refers to the presence of a distinct endothermic peak rather than a stepwise change in endothermic heat in differential scanning calorimetry (DSC). Specifically, it means that the half-width of the endothermic peak is within 10 °C when measured at a heating rate of 10 °C / min.

[0125] On the other hand, the "amorphousness" of resin refers to a half-width exceeding 10°C, exhibiting a step-like change in endothermic heat or an inability to identify a clear endothermic peak.

[0126] Amorphous polyester resin

[0127] Examples of amorphous polyester resins include condensation polymers of polycarboxylic acids and polyols. Furthermore, both commercially available and synthetic resins can be used as amorphous polyester resins.

[0128] Examples of polycarboxylic acids include, for example, aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citracic acid, itaconic acid, pentenic acid, succinic acid, alkenyl succinic acid (hexenyl succinic acid, octenyl succinic acid, dodecenyl succinic acid, pentadecenyl succinic acid, etc.), adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or their lower (e.g., alkyl esters with 1 or more but less than 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids.

[0129] Regarding polycarboxylic acids, tri- or higher carboxylic acids that can be used together with dicarboxylic acids and have a cross-linked or branched structure can be considered. Examples of tri- or higher carboxylic acids include trimellitic acid, pyromellitic acid, their anhydrides, or their lower (e.g., having 1 or more but less than 5 carbon atoms) alkyl esters.

[0130] Polycarboxylic acids can be used alone or in combination with two or more.

[0131] Examples of polyols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanediol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyols, and aromatic diols are more preferred.

[0132] As a polyol, it can be used in combination with diols to form tri- or more polyols with cross-linked or branched structures. Examples of tri- or more polyols include glycerol, trimethylolpropane, and pentaerythritol.

[0133] Polyols can be used alone or in combination with two or more.

[0134] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 80°C or lower, more preferably 50°C or higher and 70°C or lower.

[0135] In addition, the glass transition temperature is determined by the DSC curve obtained by differential scanning calorimetry (DSC), or more specifically, by the "extrapolation of the glass transition onset temperature" as described in JIS K 7121-1987 "Method for determination of the transition temperature of plastics".

[0136] The weight-average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, more preferably 7,000 or more and 500,000 or less.

[0137] The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less.

[0138] The molecular weight distribution of the amorphous polyester resin, Mw / Mn, is preferably 1.5 or more and 100 or less, more preferably 2 or more and 60 or less.

[0139] In addition, the weight-average molecular weight and number-average molecular weight were determined by gel permeation chromatography (GPC). In the GPC-based molecular weight determination, a GPC·HLC-8320GPC manufactured by TOSOH CORPORATION was used as the measuring instrument, and a TSKgel SuperHM-M (15 cm) column manufactured by TOSOH CORPORATION was used in tetrahydrofuran (THF) solvent. The weight-average molecular weight and number-average molecular weight were calculated using a molecular weight calibration curve prepared based on the determination results and using monodisperse polystyrene standard samples.

[0140] Amorphous polyester resins can be used alone or in combination with two or more. When using two or more, for example, high molecular weight and low molecular weight polymers can be used together.

[0141] Amorphous polyester resins are obtained by well-known manufacturing methods. Specifically, for example, they are obtained by setting the polymerization temperature to above 180°C and below 230°C, and by subjecting the reaction system to reduced pressure as needed, while removing water or alcohol generated during condensation and allowing the reaction to proceed.

[0142] Additionally, when the monomers of the raw materials are insoluble or immiscible under the reaction temperature conditions, a high-boiling-point solvent can be added as a co-solvent to dissolve them. In this case, the polycondensation reaction is carried out simultaneously with the distillation to remove the co-solvent. When poorly compatible monomers are present, for example, the poorly compatible monomers and the acid or alcohol intended to be polycondensed with them can be pre-condensed, and then polycondensed together with the main component.

[0143] Crystalline polyester resin

[0144] Examples of crystalline polyester resins include condensation polymers of polycarboxylic acids and polyols. Furthermore, both commercially available and synthetic resins can be used as crystalline polyester resins.

[0145] In order to facilitate the formation of a crystal structure, the crystalline polyester resin preferably uses a condensation polymer of aliphatic monomers with linear chains, rather than a condensation polymer of aromatic monomers.

[0146] Examples of polycarboxylic acids include, for example, aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, etc.), their anhydrides, or their lower (e.g., alkyl esters with 1 or more but less than 5 carbon atoms).

[0147] Regarding polycarboxylic acids, tri- or higher carboxylic acids can be used in combination with dicarboxylic acids to adopt a cross-linked or branched structure. Examples of tri-carboxylic acids include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, or their lower (e.g., alkyl esters with 1 or more but less than 5 carbon atoms).

[0148] As a polycarboxylic acid, it can be used in combination with these dicarboxylic acids, including dicarboxylic acids with sulfonic acid groups and dicarboxylic acids with olefinic double bonds.

[0149] Polycarboxylic acids can be used alone or in combination with two or more.

[0150] Examples of polyols include aliphatic diols (e.g., straight-chain aliphatic diols with 2 or more but less than 20 carbon atoms in the main chain). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosenediol. Among these, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols.

[0151] Regarding polyols, tri- or higher alcohols that can be used in combination with diols and have a cross-linked or branched structure can be included. Examples of tri- or higher alcohols include glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0152] Polyols can be used alone or in combination with two or more.

[0153] Here, regarding polyols, for example, it is preferable to set the content of aliphatic diols to be 80 mol% or more, and more preferably 90 mol% or more.

[0154] The melting temperature of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 90°C or lower, and even more preferably 60°C or higher and 85°C or lower.

[0155] In addition, the melting temperature is determined based on the DSC curve obtained by differential scanning calorimetry (DSC), using the "melting peak temperature" described in JISK7121-1987 "Method for determining the transformation temperature of plastics".

[0156] The weight-average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 50,000 or less.

[0157] Similar to amorphous polyester resins, crystalline polyester resins are obtained, for example, by well-known manufacturing methods.

[0158] In addition, polyester resins can be used to make mixed resins containing polyester resin segments and styrene-acrylic acid copolymer segments.

[0159] As for the content of the adhesive resin, relative to the total amount of colorant particles, it is preferably 40% or more and 95% or less by mass, more preferably 50% or more and 92% or less by mass, and even more preferably 55% or more and 90% or less by mass.

[0160] <Coloring agent>

[0161] Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzidine yellow, vat yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vogan orange, Vinegar magenta, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lixol red, rhodamine B lake, lake red C, pigment red, Bengal rose red, aniline blue, ultramarine blue, copper oil blue, and methyl chloride. Various pigments such as base blue, phthalocyanine blue, pigment blue, phthalocyanine green, malachite green oxalate, titanium compounds, inorganic pigments such as silica, aluminum, and mica, or various dyes such as acridine, xanthine, azo, benzoquinone, azazine, anthraquinone, thioindigo, dioxazine, thiazine, azomethyl alkali, indigo, phthalocyanine, aniline black, polymethyl, triphenylmethane, diphenylmethane, and thiazole.

[0162] Colorants are not limited to substances that absorb light in the visible region. For example, colorants can also be substances that absorb light in the near-infrared region, fluorescent colorants, or colorants with luminescence.

[0163] Colorants can be used alone or in combination with two or more.

[0164] Colorants can be surface-treated as needed, and can be used in combination with dispersants. Furthermore, multiple colorants can be used in combination.

[0165] The content of the colorant, relative to the total amount of the colorant particles, is preferably 1% or more and 30% or less by mass, more preferably 3% or more and 15% or less by mass.

[0166] <Other Additives>

[0167] Other additives include, for example, well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in the colorant particles as internal additives.

[0168] <Characteristics of toning agent particles, etc.>

[0169] Toner particles can be monolayer toner particles or so-called core-shell toner particles consisting of a core (nuclear particle) and a coating layer (shell) covering the core.

[0170] The volume average particle size (D50v) of the colorant particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0171] In addition, various average particle sizes and particle size distribution parameters of the colorant particles were measured using a Coulter Multisizer 3 (manufactured by BECKMAN COULTER) and an ISOTON-II electrolyte (manufactured by BECKMAN COULTER).

[0172] During the determination, 0.5 mg to 50 mg of the test sample is added to 2 ml of a 5% aqueous solution of a surfactant (e.g., preferably sodium alkylbenzene sulfonate) as a dispersant. This is then added to 100 ml to 150 ml of electrolyte.

[0173] The electrolyte containing the suspended sample was dispersed using an ultrasonic disperser for 1 minute. The particle size distribution of particles with a diameter ranging from 2 μm to 60 μm was determined using a Coulter Multisizer 3 with a pore diameter of 100 μm. Additionally, 50,000 particles were sampled.

[0174] For particle size ranges (intervals) segmented based on the particle size distribution to be measured, the cumulative volume distribution and cumulative number distribution are depicted separately from the small diameter side. The particle size that will become 16% cumulative is defined as the volumetric particle size D16v and the number particle size D16p. The particle size that will become 50% cumulative is defined as the volume average particle size D50v and the cumulative number average particle size D50p. The particle size that will become 84% cumulative is defined as the volumetric particle size D84v and the number particle size D84p.

[0175] Use these, from (D84v / D16v) 1 / 2 The volumetric particle size distribution index (GSDv) was calculated from (D84p / D16p). 1 / 2 The number granularity distribution index (GSDp) was calculated.

[0176] The average roundness of the colorant particles is preferably 0.90 or higher and 1.00 or lower, and more preferably 0.92 or higher and 0.98 or lower.

[0177] The average roundness of the toner particles is calculated by (circumference of the equivalent circle) / (circumference) [(circumference of a circle with the same projected area as the particle image) / (circumference of the particle projected image)]. Specifically, it is a value determined using the following method.

[0178] First, toner particles, the object of measurement, are aspirated and collected, forming a flat flow that causes them to flash light momentarily. This is then read as a still image of the particles, and the particle image is analyzed using a flow cytometry particle image analyzer (Parshe Analyzer PAS, manufactured by HOSOKAWA MICRON CORPORATION). Furthermore, the number of samples used to determine the average roundness is set to 10,000.

[0179] In addition, when the colorant contains additives, the colorant (developer) to be measured is dispersed in water containing a surfactant and then subjected to ultrasonic treatment to obtain colorant particles with additives removed.

[0180] [External Additives]

[0181] Examples of additives include inorganic particles. Examples of such inorganic particles include SiO2, TiO2, Al2O3, SrTiO3, CaTiO3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, and K2O·(TiO2). n Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, etc.

[0182] The surface of the inorganic particles used as additives is preferably subjected to a hydrophobic treatment, for example. This hydrophobic treatment is performed by, for example, immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited; examples include silane-based coupling agents, silicone oils, titanate-based coupling agents, and aluminum-based coupling agents. They can be used alone or in combination of two or more.

[0183] The amount of the hydrophobic treatment agent is typically 1 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the inorganic particles.

[0184] Other examples of additives include resin particles (such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning and activating agents (such as metal salts of higher fatty acids, such as zinc stearate, and particles of higher alcohols).

[0185] The amount of additive used as an additive, relative to the colorant particles, is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 6.0% by mass or less.

[0186] [Manufacturing method of toner for electrostatic image development]

[0187] The toner for electrostatic image development described in this embodiment is obtained by adding an additive to the toner particles after manufacturing the toner particles.

[0188] Colorant particles can be manufactured by any of the following methods: dry manufacturing (e.g., mixing and pulverizing) or wet manufacturing (e.g., coagulation polymerization, suspension polymerization, dissolution suspension polymerization). They are not particularly limited to these methods and can employ known manufacturing methods. Among these, coagulation polymerization is preferred, for example, for obtaining colorant particles.

[0189] Specifically, for example, when colorant particles are manufactured by agglomeration and unification, the colorant particles are manufactured through the following steps:

[0190] The process of mixing a 0 resin particle dispersion containing 0 resin particles forming a domain, a 1 resin particle dispersion containing 1 resin particles serving as a binder resin, a colorant dispersion containing a colorant, and a release agent particle dispersion containing release agent particles (hereinafter also referred to as "release agent particles"), and then agglomerating each particle and the colorant in the obtained dispersion to form a first aggregated particle (first aggregated particle forming process).

[0191] After obtaining a first aggregated particle dispersion in which the first aggregated particles are dispersed, a second resin particle, serving as a binding resin, is added to the first aggregated particle dispersion to cause the second resin particle to aggregate on the surface of the first aggregated particles to form a second aggregated particle (the second aggregated particle forming process); and

[0192] The process of heating the dispersion of the second aggregated particles containing the second aggregated particles to fuse / unite the second aggregated particles to form colorant particles (fusion / unification process).

[0193] In addition, this cohesion-integration method is described as a method for preparing colorant particles containing a binding resin, a colorant, and a release agent, but the colorant and release agent are components included in the colorant particles as needed.

[0194] The following is a detailed explanation of each process.

[0195] -Preparation steps for each dispersion-

[0196] First, prepare each dispersion to be used in the coagulation and unification method. Specifically, prepare a dispersion of resin particles containing resin particles of the 0th resin domain, a dispersion of resin particles containing resin particles of the 1st resin domain as a binder, a dispersion of colorant containing colorant, a dispersion of resin particles containing resin particles of the 2nd resin domain as a binder, and a dispersion of release agent particles containing release agent particles.

[0197] In addition, in each dispersion preparation process, the 0th resin particle, the 1st resin particle, and the 2nd resin particle will be referred to as "resin particles" for explanation.

[0198] Here, the resin particle dispersion is prepared, for example, by using a surfactant to disperse the resin particles in a dispersion medium.

[0199] Examples of dispersion media for resin particle dispersions include aqueous media.

[0200] Examples of aqueous media include distilled water, ion-exchanged water, and alcohols. They can be used individually or in combination with two or more.

[0201] Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyols. Among these, anionic and cationic surfactants are particularly noteworthy. Nonionic surfactants can be used in combination with either anionic or cationic surfactants.

[0202] Surfactants can be used alone or in combination with two or more.

[0203] In resin particle dispersions, methods for dispersing resin particles in a dispersion medium include, for example, rotary shear homogenizers or general dispersion methods such as ball mills, sand mills, and DYNO-MILLs with media. Furthermore, depending on the type of resin particles, for example, phase inversion emulsification can be used to disperse resin particles in the resin particle dispersion.

[0204] In addition, the phase inversion emulsification method refers to the following method: the resin to be dispersed is dissolved in a hydrophobic organic solvent soluble in the resin, an alkali is added to the organic continuous phase (O phase) for neutralization, and then an aqueous medium (W phase) is introduced, thereby converting the resin from W / O to O / W (so-called phase inversion) to form a discontinuous phase, thereby dispersing the resin into particles in the aqueous medium.

[0205] The volume average particle size of the resin particles dispersed in the resin particle dispersion is preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and even more preferably 0.1 μm or more and 0.6 μm or less.

[0206] Furthermore, regarding the volume average particle size of the resin particles, the particle size range (interval) obtained by dividing the particle size distribution using a laser diffraction particle size distribution measuring device (e.g., manufactured by HORIBA, Ltd., LA-960) is used. Regarding the cumulative distribution plotted from the smallest particle size side, the particle size that constitutes the cumulative 50% of all particles is measured as the volume average particle size D50v. The volume average particle size of particles in other dispersions is also measured in the same manner.

[0207] The content of resin particles contained in the resin particle dispersion is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less.

[0208] In addition, colorant dispersions and release agent particle dispersions can also be prepared in the same manner as resin particle dispersions. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion are the same for the colorant dispersed in the colorant dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0209] -First stage of condensed particle formation-

[0210] Next, the 0th resin particle dispersion, the 1st resin particle dispersion, the colorant dispersion, and the release agent particle dispersion are mixed.

[0211] Then, in the mixed dispersion, the 0th resin particles, the 1st resin particles, the colorant and the release agent particles are heterogeneously aggregated to form the first aggregated particles containing the 0th resin particles, the 1st resin particles, the colorant and the release agent particles.

[0212] Specifically, for example, a coagulant is added to a dispersion formed by mixing a 0th resin particle dispersion, a 1st resin particle dispersion, a colorant dispersion, and a release agent particle dispersion, and the pH of the mixed dispersion is adjusted to acidic (e.g., pH 2 or higher and 5 or lower). After adding a dispersing stabilizer as needed, the temperature range is set to 20°C or higher and 50°C or lower, so that the particles dispersed in the mixed dispersion agglomerate to form the 1st agglomerated particles.

[0213] In the first coagulated particle formation step, for example, while stirring the mixed dispersion using a rotary shear homogenizer, the coagulant can be added at room temperature (e.g., 25°C), and the pH of the mixed dispersion can be adjusted to acidic (e.g., pH 2 or higher and 5 or lower). After adding a dispersion stabilizer as needed, the heating process described above can be performed.

[0214] Examples of coagulants include surfactants with opposite polarity to the surfactants used as dispersants added to the mixed dispersion, inorganic metal salts, and metal complexes with a polarity of two or higher. In particular, when metal complexes are used as coagulants, the amount of surfactant used is reduced, and the charged properties are improved.

[0215] Additives that form complexes or similar bonds with the metal ions of the coagulant can be used, depending on the requirements. Chelating agents can be used as such additives.

[0216] Examples of inorganic metal salts include calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.

[0217] Water-soluble chelating agents can be used as chelating agents. Examples of chelating agents include tartaric acid, citric acid, gluconic acid and other hydroxycarboxylic acids, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), etc.

[0218] The amount of chelating agent added is, for example, more than 0.01 parts by mass and less than 5.0 parts by mass relative to 100 parts by mass of the first resin particles, and more preferably more than 0.1 parts by mass and less than 3.0 parts by mass.

[0219] Furthermore, to adjust the effectiveness of the chelating agent, an alkali can be added to adjust the pH of the system.

[0220] -Second stage of condensed particle formation-

[0221] Next, after obtaining the first aggregate particle dispersion containing the first aggregate particles, the second resin particle dispersion containing the second resin particles is added to the first aggregate particle dispersion.

[0222] In addition, the second resin particle can be of the same type as the first resin particle, or it can be of a different type.

[0223] Then, in the dispersion of the first aggregated particles and the second resin particles, the second resin particles are aggregated on the surface of the first aggregated particles. At this time, a release agent particle dispersion may also be added to aggregate the second resin particles and the release agent particles on the surface of the first aggregated particles. Specifically, for example, in the first aggregated particle forming process, when the first aggregated particles reach the target particle size, a second resin particle dispersion is added to the first aggregated particle dispersion, and heating is performed below the glass transition temperature of the second resin particles.

[0224] Then, by setting the pH of the dispersion to a range of approximately 6.5 above and 8.5 below, coagulation is stopped.

[0225] Thus, a second condensed particle is obtained in such a way that the second resin particle is attached to the surface of the first condensed particle.

[0226] -Integration / Unification Process-

[0227] Next, the dispersion of the second aggregated particles, in which the second aggregated particles are dispersed, is heated, for example, to a temperature above the glass transition temperature of the first and second resin particles (e.g., a temperature 10 to 30°C higher than the glass transition temperature of the first and second resin particles), so that the second aggregated particles are fused / integrated to form colorant particles.

[0228] Furthermore, in order to control the shape, acid can be added as needed to adjust the pH of the system.

[0229] After the above process, colorant particles can be obtained.

[0230] Furthermore, in the coagulation and unification method described above, the first coagulated particles can be fused / unified to form colorant particles without performing the second coagulated particle formation step. Also, the second coagulated particle formation step can be performed repeatedly.

[0231] Here, after the fusion / integration process is completed, the toner particles in the dispersion are subjected to a known cleaning process, a solid-liquid separation process, and a drying process to obtain dry toner particles.

[0232] There are no particular restrictions on the cleaning process, but from the viewpoint of electrical conductivity, it is preferable to fully implement displacement cleaning based on ion-exchange water. Furthermore, there are no particular restrictions on the solid-liquid separation process, but from a productivity perspective, suction filtration, pressure filtration, etc., are preferred. Also, there are no particular restrictions on the drying method, but from a productivity perspective, freeze drying, airflow drying, fluidized bed drying, vibrating fluidized bed drying, etc., are preferred.

[0233] Furthermore, the colorant involved in this embodiment is manufactured, for example, by adding an additive to and mixing the obtained dried colorant particles. The mixing is preferably performed using, for example, a V-type stirrer, a Henschel mixer, or a Rhodes mixer. The additive can be mixed with the colorant particles all at once, or the additive can be added to the colorant particles in stages and mixed multiple times. Moreover, if necessary, a vibrating screen, a pneumatic screen, or the like can be used to remove coarse particles of the colorant.

[0234] (Electrostatic image developer)

[0235] The electrostatic image developer involved in this embodiment includes at least the electrostatic image developing tone agent involved in this embodiment.

[0236] The electrostatic image developer involved in this embodiment may be a single-component developer containing only the electrostatic image developing toner involved in this embodiment, or it may be a two-component developer formed by mixing the electrostatic image developing toner with a carrier.

[0237] There are no particular limitations on the carrier, and well-known carriers can be cited. Examples of carriers include coated carriers formed by coating resin onto the surface of a core material made of magnetic powder; magnetic powder dispersion carriers in which magnetic powder is dispersed and incorporated into a matrix resin; and resin impregnation carriers formed by impregnating resin in porous magnetic powder.

[0238] Magnetic powder dispersion carriers and resin impregnation carriers can be carriers made by using the constituent particles of the carrier as the core material and coating its surface with resin.

[0239] Examples of magnetic powders include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0240] In particular, magnetite and ferrite are preferred as magnetic powders. Magnetic powders can be used as particles formed by dispersing magnetic powder in resin.

[0241] Examples of coating resins and matrix resins include styrene-(meth)acrylic resin; polyolefin resins such as polyethylene resin and polypropylene resin; polyethylene-based or polyvinylene-based resins such as polystyrene, (meth)acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylcarbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymers; linear silicone resins or their modifications composed of organosiloxane bonds; fluoropolymers such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; and epoxy resins.

[0242] The coating resin and matrix resin preferably include, for example, (meth)acrylic resin, and more preferably, (meth)acrylic resin having an alicyclic structure. The coating resin and matrix resin may contain nitrogen-containing (meth)acrylic resin.

[0243] The resin comprises, for example, more preferably, 50% or more of (meth)acrylic resin relative to the total mass of the coating resin and the matrix resin, and more preferably 80% or more of (meth)acrylic resin relative to the total mass of the coating resin and the matrix resin.

[0244] In particular, the coating resin and the matrix resin preferably include, for example, an alicyclic (meth)acrylic resin as the (meth)acrylic resin.

[0245] The coating resin and matrix resin may contain conductive particles and other additives. Examples of conductive particles include metals such as gold, silver, and copper, carbon black, titanium dioxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0246] Other additives include particles that overlap with the aforementioned conductive particles, such as metal oxide particles like silicon dioxide, titanium dioxide, zinc oxide, and tin oxide; metal compound particles like barium sulfate, aluminum borate, and potassium titanate; and metal particles like gold, silver, and copper. Among these, silicon dioxide particles are preferred, for example.

[0247] The aforementioned particles are preferably present in a proportion of 10% to 60% by mass relative to the total mass of the resin layer.

[0248] Methods for coating the surface of a core material with resin include coating by using a coating layer formed by dissolving a coating resin and various additives (as needed) in a suitable solvent. The solvent is not particularly limited; it can be selected based on factors such as the type of resin used and its suitability for coating.

[0249] Specific resin coating methods include: immersion method in which the core material is immersed in a coating layer forming solution; spraying method in which the coating layer forming solution is sprayed onto the surface of the core material; fluidized bed method in which the coating layer forming solution is sprayed while the core material is suspended by flowing air; and kneading coating method in which the core material and the coating layer forming solution are mixed in a kneading coating machine and then the solvent is removed.

[0250] The mixing ratio (mass ratio) of the toner and carrier in the two-component developer is preferably toner:carrier = 1:100 to 30:100, more preferably 3:100 to 20:100.

[0251] (Image forming apparatus, image forming method)

[0252] The image forming apparatus and image forming method involved in this embodiment will be described.

[0253] The image forming apparatus according to this embodiment includes: an image holder; a charging device for charging the surface of the image holder; an electrostatic image forming apparatus for forming an electrostatic image on the charged surface of the image holder; a developing apparatus for containing an electrostatic image developer and developing the electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer; a transfer apparatus for transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing apparatus for fixing the toner image transferred to the surface of the recording medium. Furthermore, the electrostatic image developer according to this embodiment is used as the electrostatic image developer.

[0254] In the image forming apparatus of this embodiment, an image forming method (the image forming method of this embodiment) is implemented including the following steps: a charging step, which charges the surface of an image holder; an electrostatic image forming step, which forms an electrostatic image on the charged surface of the image holder; a developing step, which develops the electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer of this embodiment; a transfer step, which transfers the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step, which fixes the toner image transferred to the surface of the recording medium.

[0255] The image forming apparatus according to this embodiment is applicable to the following known image forming apparatuses: a direct transfer method apparatus that directly transfers a toner image formed on the surface of an image holder to a recording medium; an intermediate transfer method apparatus that transfers a toner image formed on the surface of an image holder to the surface of an intermediate transfer body in one step, and then transfers the toner image already transferred to the surface of the intermediate transfer body to the surface of the recording medium in a second step; an apparatus equipped with a cleaning device that cleans the surface of the image holder before it becomes charged after the toner image is transferred; or an electrostatic elimination device that irradiates the surface of the image holder with electrostatic elimination light to eliminate static electricity after the toner image is transferred and before it becomes charged, etc.

[0256] In the case of an intermediate transfer method apparatus, the transfer apparatus is, for example, suitable for having the following structure: an intermediate transfer body on which a toner image is transferred; a primary transfer apparatus that transfers the toner image formed on the surface of an image holder onto the surface of the intermediate transfer body in a primary transfer; and a secondary transfer apparatus that transfers the toner image already transferred to the surface of the intermediate transfer body onto the surface of the recording medium in a secondary transfer.

[0257] Furthermore, in the image forming apparatus according to this embodiment, for example, the portion including the developing apparatus can be a cassette structure (processing cassette) that is detachable from the image forming apparatus. As a processing cassette, for example, a processing cassette having a developing apparatus that contains the electrostatic image developer according to this embodiment is preferably used.

[0258] The following shows an example of the image forming apparatus according to this embodiment, but it is not limited thereto. Furthermore, the main parts shown in the figures will be described, while the descriptions of other parts will be omitted.

[0259] Figure 1 This is a schematic structural diagram showing the image forming apparatus according to this embodiment.

[0260] Figure 1The image forming apparatus shown includes first to fourth image forming units 10Y, 10M, 10C, and 10K in an electrophotographic manner, which output images of yellow (Y), magenta (M), cyan (C), and black (K) colors based on color-decomposed image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side-by-side, separated from each other by a predetermined distance in the horizontal direction. Furthermore, these units 10Y, 10M, 10C, and 10K can be a processing unit detachable from the image forming apparatus.

[0261] Above each of the attached figures for units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20, serving as an intermediate transfer body, is provided extending through each unit. The intermediate transfer belt 20 is wound around a drive roller 22, which is arranged separately from each other in a left-to-right direction in the figure, and a support roller 24, which contacts the inner surface of the intermediate transfer belt 20, and travels in a direction from the first unit 10Y toward the fourth unit 10K. Furthermore, the support roller 24 is subjected to force by a spring (not shown) or the like in a direction away from the drive roller 22, thereby applying tension to the intermediate transfer belt 20 wound around both. Additionally, an intermediate transfer body cleaning device 30 is provided on the outer peripheral surface of the intermediate transfer belt 20, opposite to the drive roller 22.

[0262] Furthermore, the toner, which includes four colors of toner—yellow, magenta, turquoise, and black—contained in toner cartridges 8Y, 8M, 8C, and 8K, is supplied to the developing apparatus (an example of a developing apparatus) 4Y, 4M, 4C, and 4K of each unit 10Y, 10M, 10C, and 10K.

[0263] Units 1 through 4, 10Y, 10M, 10C, and 10K, have the same structure. Therefore, we will use unit 10Y, which forms the yellow image and is located on the upstream side of the intermediate transfer belt in the direction of travel, as an example for explanation. In addition, the explanation of units 2 through 4, 10M, 10C, and 10K, will be omitted by marking the parts that are the same as those of unit 10Y with reference symbols that are magenta (M), turquoise (C), and black (K) instead of yellow (Y).

[0264] Unit 10Y has a photoreceptor 1Y that functions as an image holder. Around the photoreceptor 1Y are arranged in sequence: a charging roller (an example of a charging device) 2Y, which charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic image forming apparatus) 3, which uses a laser beam 3Y based on a color-decomposed image signal to expose the charged surface and form an electrostatic image; a developing device (an example of a developing apparatus) 4Y, which supplies charged toner to the electrostatic image and develops the image; a primary transfer roller (an example of a primary transfer apparatus) 5Y, which transfers the developed toner image onto an intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning device) 6Y, which removes toner residue remaining on the surface of the photoreceptor 1Y after the primary transfer.

[0265] Furthermore, the primary transfer roller 5Y is disposed inside the intermediate transfer belt 20 and positioned opposite the photosensitive element 1Y. Moreover, each of the primary transfer rollers 5Y, 5M, 5C, and 5K is connected to a bias power supply (not shown) for applying a primary transfer bias voltage. The transfer bias voltage applied to each primary transfer roller can be changed by controlling a control unit (not shown).

[0266] The following describes the action of forming a yellow image in Unit 10Y.

[0267] First, before performing the action, the surface of the photoreceptor 1Y is charged to a potential of -600V to -800V using the charging roller 2Y.

[0268] Photoreceptor 1Y has good electrical conductivity (e.g., volume resistivity at 20°C: 1 × 10⁻⁶). -6 A photosensitive layer is formed by laminating a substrate with a resistivity of Ω·cm or less. This photosensitive layer is typically high resistivity (the resistivity of a typical resin), but it has the property that the resistivity of the portion irradiated by the laser beam 3Y changes when irradiated. Therefore, based on yellow image data sent from a control unit (not shown), the laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure apparatus 3. The laser beam 3Y irradiates the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic image of a yellow image pattern on the surface of the photoreceptor 1Y.

[0269] An electrostatic image is an image formed on the surface of a photoreceptor 1Y by means of a charge. It is a so-called negative latent image. It is formed by the decrease of resistivity of the irradiated part of the photosensitive layer due to the laser beam 3Y, and the flow of the charged charge on the surface of the photoreceptor 1Y. On the other hand, the charge remains in the part that is not irradiated by the laser beam 3Y.

[0270] As the photoreceptor 1Y moves forward, the electrostatic image formed on the photoreceptor 1Y rotates to a predetermined developing position. Then, at this developing position, the electrostatic image on the photoreceptor 1Y is transformed into a toner image by the developing apparatus 4Y (developed image).

[0271] The developing apparatus 4Y contains, for example, an electrostatic image developer comprising at least a yellow toner and a carrier. The yellow toner is agitated and triboelectrically charged inside the developing apparatus 4Y, thus acquiring a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y and remaining on the developer roller (an example of a developer holder). Then, the surface of the photoreceptor 1Y passes through the developing apparatus 4Y, causing the yellow toner to electrostatically adhere to the destatically neutralized latent image portion on the surface of the photoreceptor 1Y, thereby developing the latent image through the yellow toner. The photoreceptor 1Y, with the yellow toner image formed, continues to travel at a predetermined speed, and the developed toner image on the photoreceptor 1Y is transferred to a predetermined transfer position.

[0272] If the yellow toner image on the photoreceptor 1Y is transferred to the primary transfer position, a primary transfer bias is applied to the primary transfer roller 5Y. An electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image, transferring the toner image on the photoreceptor 1Y onto the intermediate transfer belt 20. The applied transfer bias at this time is a (+) polarity opposite to the polarity (-) of the toner, for example, controlled by the control unit (not shown) to be +10 μA in the first unit 10Y.

[0273] On the other hand, the toner remaining on the photoreceptor 1Y is removed and recycled by the photoreceptor cleaning device 6Y.

[0274] Furthermore, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K after the 10M of the second unit is also controlled according to the first unit.

[0275] Thus, the intermediate transfer belt 20, which has been transferred with a yellow toner image through the first unit 10Y, is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, thereby superimposing the toner images of each color for multiple transfers.

[0276] The intermediate transfer belt 20, through which four colors of toner images have been transferred multiple times in units 1 to 4, reaches the secondary transfer section, which consists of the intermediate transfer belt 20, a support roller 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roller (an example of a secondary transfer device) 26 disposed on the outer peripheral side of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is supplied to the gap between the secondary transfer roller 26 and the intermediate transfer belt 20 via a supply mechanism at a predetermined time, thereby applying a secondary transfer bias to the support roller 24. The applied transfer bias at this time is of the same polarity (-) as the toner, and the electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, thereby transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. Furthermore, the secondary transfer bias at this time is determined by the resistance detected by a resistance detection device (not shown) that detects the resistance of the secondary transfer section, and is controlled by voltage.

[0277] Then, the recording paper P is fed into the pressing part (pressing part) of a pair of fixing rollers in the fixing device (an example of a fixing device) 28, and the toner image is fixed on the recording paper P, thereby forming a fixed image.

[0278] Recording paper P used for transferring toner images can include, for example, ordinary paper used in electrophotographic copiers and printers. Recording media, besides recording paper P, can include OHP film, etc.

[0279] To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth, for example, coated paper made by coating the surface of ordinary paper with resin, or coated paper for printing.

[0280] The recording paper P, having completed the fixing of the color image, is conveyed toward the discharge section, thus ending a series of color image forming actions.

[0281] <Treatment box / Toner box>

[0282] The processing box involved in this embodiment will be described.

[0283] The processing cartridge involved in this embodiment is a processing cartridge equipped with a developing device and detachable from an image forming apparatus. The developing device contains the electrostatic image developer involved in this embodiment, and uses the electrostatic image developer to develop the electrostatic image formed on the surface of the image holder into a toner image.

[0284] Furthermore, the processing box involved in this embodiment is not limited to the structure described above, and may also be a structure that includes a developing device and, as needed, includes at least one of other devices selected from an image holder, a charging device, an electrostatic image forming device, and a transfer device.

[0285] The following shows an example of the processing box according to this embodiment, but it is not limited thereto. In addition, the main parts shown in the figure will be described, while the description of other parts will be omitted.

[0286] Figure 2 This is a schematic structural diagram of the processing box involved in this embodiment.

[0287] Figure 2 The processing box 200 shown is constructed, for example, by using a housing 117 having a mounting rail 116 and an opening 118 for exposure to hold a photoreceptor 107 (an example of an image holder), a charging roller 108 (an example of a charging device) having a charging roller 108 around the photoreceptor 107, a developing device 111 (an example of a developing device) and a photoreceptor cleaning device 113 (an example of a cleaning device) integrally combined and held in a box, and is made into a box.

[0288] in addition, Figure 2 In the diagram, 109 represents an exposure device (an example of an electrostatic image forming device), 112 represents a transfer device (an example of a transfer device), 115 represents a fixing device (an example of a fixing device), and 300 represents recording paper (an example of a recording medium).

[0289] Next, the colorant cartridge according to this embodiment will be described.

[0290] The toner cartridge according to this embodiment is a toner cartridge that contains the toner according to this embodiment and is detachable from the image forming apparatus. The toner cartridge contains supplementary toner for supplying to the developing apparatus provided within the image forming apparatus.

[0291] in addition, Figure 1 The image forming apparatus shown is one in which toner cartridges 8Y, 8M, 8C, and 8K are detachable. The developing units 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to each developing unit (color) via toner supply tubes (not shown). Furthermore, the toner cartridge is replaced when the amount of toner contained within it decreases.

[0292] Example

[0293] Hereinafter, the embodiments of the present invention will be described in detail with reference to the examples, but the embodiments of the present invention are not limited to these examples.

[0294] In the following description, unless otherwise specified, “parts” and “%” are quality standards.

[0295] Unless otherwise specified, synthesis, processing, manufacturing, etc., shall be carried out at room temperature (25℃±3℃).

[0296] (Example 1)

[0297] <Preparation of Toning Agent Particles (1)>

[0298] [Preparation of amorphous polyester resin dispersion (1) (PES1)]

[0299] ·Terephthalic acid: 100 moles

[0300] Ethylene glycol: 60 moles

[0301] Propylene glycol: 30 moles

[0302] • Bisphenol A propylene oxide 2-molar adduct: 10 molar parts

[0303] The above-mentioned materials were loaded into a reaction vessel equipped with a stirring device, a nitrogen inlet pipe, a temperature sensor, and a distillation column. The temperature was raised to 190°C over 1 hour, and 1.2 parts of dibutyltin oxide were added relative to 100 parts of the above-mentioned materials. While distilling to remove the generated water, the temperature was raised to 240°C over 6 hours. Then, the temperature was maintained at 240°C for 3 hours for a dehydration condensation reaction. After cooling, an amorphous polyester resin (1) was obtained.

[0304] The obtained amorphous polyester resin (1) had an ester group concentration of 38.9% by mass.

[0305] • Amorphous polyester resin (1): 100 parts

[0306] · Methyl ethyl ketone: 60 parts

[0307] Isopropyl alcohol: 15 parts

[0308] • 10% ammonia solution: 3.6 parts

[0309] The aforementioned materials were added to a jacketed reaction tank equipped with a condenser, thermometer, drip device, and anchor fins. The amorphous polyester resin (1) was dissolved while the liquid temperature was maintained at 50°C and the mixture was stirred at 100 rpm in a water-circulating thermostatic bath. Next, the water-circulating thermostatic bath was set to 40°C, and a total of 300 parts of ion-exchange water maintained at 40°C was added dropwise at a rate of 3 parts / min to induce phase inversion and prepare an emulsion.

[0310] The obtained emulsion was placed in a flask and placed in an evaporator equipped with a vacuum control unit via a trap ball. While rotating the flask, it was heated in a 60°C hot water bath, and the pressure was reduced to 7 kPa while preventing boiling over. After removing the solvent, the pressure was restored to atmospheric pressure, and the flask was water-cooled to obtain a dispersion. Ion-exchanged water was added to the obtained dispersion to obtain an amorphous polyester resin dispersion with a solid content of 20% by mass (1).

[0311] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (1)(B1)]

[0312] -Preparation of emulsion (1)-

[0313] <<Emulsion (1)>>

[0314] Styrene: 40 parts

[0315] • n-Butyl acrylate: 58.5 parts

[0316] • Divinylbenzene: 1.5 parts

[0317] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0318] • Ion-exchanged water: 98.8 parts

[0319] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (1).

[0320] After purging the reaction vessel, which is equipped with a stirring device and a nitrogen inlet pipe, with nitrogen, 0.4 parts of anionic surfactant (ELEMINOL MON-2) and 100 parts of ion-exchanged water were added. While stirring the reaction solution, it was heated in an oil bath to a temperature of 70°C. After adding 5 parts of emulsion (1), 10 parts of a 10% by mass ammonium persulfate aqueous solution were added and maintained for 30 minutes.

[0321] Then, while maintaining the temperature of the reaction solution at 70°C, 195 parts of emulsion (1) were gradually added to the reaction vessel by pump over a period of 60 minutes.

[0322] After the addition was completed, the mixture was kept for 60 minutes, and then 1 part of 10% by mass ammonium persulfate was added. After keeping the mixture for another 3 hours, it was cooled to room temperature. Then, ion-exchanged water and nitric acid were added to make the solid component concentration 20% by mass, thus preparing a styrene-(meth)acrylate copolymer particle dispersion (1).

[0323] The obtained resin particles had an ester group concentration of 17.0% by mass.

[0324] [Preparation of release agent particle dispersion (1)]

[0325] • Paraffin w1 (HNP9, manufactured by NIPPON SEIRO CO.,LTD.): 100 parts

[0326] • Anionic surfactant (NEOPELEX G-65, manufactured by Kao Corporation): 5 parts

[0327] • Ion-exchanged water: 300 parts

[0328] The above materials were mixed and heated to 100°C, and dispersed using a homogenizer (ULTRA TURRAX T50). Furthermore, the dispersion was treated with a Manton-Gaulin high-pressure homogenizer (manufactured by Gaulin Corporation), and ion-exchanged water was added to the dispersion to obtain a release agent particle dispersion with a solid content of 20% by mass (1).

[0329] The ester concentration of the release agent particles in the release agent particle dispersion (1) is 0% by mass.

[0330] [Preparation of colorant dispersion]

[0331] • Carbon black (Regel 330, manufactured by Cabot Corporation): 110 parts

[0332] • Anionic surfactant (NEOPELEX G-65, manufactured by Kao Corporation): 6 parts

[0333] • Ion-exchanged water: 300 parts

[0334] The above materials were mixed and dispersed for 10 minutes using a homogenizer (ULTRA TURRAX T50, manufactured by IKA). Ion-exchanged water was added to the dispersion to obtain a colorant dispersion with a solid content of 20% by mass. The volume average particle size of the colorant particles in the dispersion was 220 nm.

[0335] <Preparation of Toning Agent (1)>

[0336] • Amorphous polyester resin dispersion (1) (solid content 20% by mass): 51 parts

[0337] • Styrene-(meth)acrylate copolymer particle dispersion (1) (solid content 20% by mass): 8 parts

[0338] • Colorant dispersion (20% by mass of solids): 8 parts

[0339] • Release agent particle dispersion (1) (solid content 20% by mass): 7 parts

[0340] • Anionic surfactant (ELEMINOL MON-2): 0.7 parts

[0341] • Ion-exchanged water: 50 parts

[0342] The above materials were placed in a reaction vessel equipped with a thermometer, pH meter, and stirrer. The reaction vessel was kept at 20°C and stirred at 150 rpm for 30 minutes. Next, 0.3N nitric acid aqueous solution was added to adjust the pH to 5.0. Then, a 2% aluminum sulfate aqueous solution was added while dispersing the mixture using a homogenizer (ULTRA TURRAX T50). The mixture was then stirred and heated to 45°C at a rate of 0.4°C / min, and maintained at this temperature for 30 minutes.

[0343] Next, 26 parts of amorphous polyester resin dispersion (1) were added and maintained for 30 minutes. Then, 1.0N (=1.0mol / L) sodium hydroxide aqueous solution was added to adjust the pH to 8.5 and maintained for 15 minutes. Then, the temperature was increased to 80°C at a rate of 1°C / min while stirring continuously and maintained at 80°C for 5 hours. Then, cooling and solid-liquid separation were performed, and the solid material was washed with ion-exchanged water. Then, the solid material was dried in a freeze vacuum dryer for 24 hours to obtain colorant particles (1) with a volume average particle size of 5.4μm.

[0344] Toner (1) was obtained by mixing 100 parts of toner particles (1) and 2.0 parts of hydrophobic silica (manufactured by NIPPON AEROSIL CO., LTD., trade name: RY200) using a Henschel mixer.

[0345] The c2 / c1 ratio of the colorant (1) is 0.44.

[0346] (Examples 2 to 27, and Comparative Examples 1 and 2)

[0347] The types and amounts of amorphous polyester resin, resin particles, and release agent were changed to those listed in Table 1. Otherwise, colorants were prepared in the same manner as in Example 1.

[0348] The following shows the preparation methods of various amorphous polyester resins, the preparation methods of resin particles, and the types of release agents.

[0349] [Preparation of amorphous polyester resin dispersion (2) (PES2)]

[0350] In the preparation of amorphous polyester resin (1), the loading of materials was changed as described below, and amorphous polyester resin (2) was obtained in the same manner otherwise.

[0351] ·Terephthalic acid: 70 moles

[0352] Fumaric acid: 30 moles

[0353] Ethylene glycol: 65 moles

[0354] Propylene glycol: 35 moles

[0355] The obtained amorphous polyester resin (2) had an ester group concentration of 48.0% by mass.

[0356] In the preparation of the amorphous polyester resin dispersion (1), the amorphous polyester resin (1) was changed to the amorphous polyester resin (2), and otherwise, an amorphous polyester resin dispersion (2) with a solid content of 20% by mass was obtained in the same manner.

[0357] [Preparation of amorphous polyester resin dispersion (3) (PES3)]

[0358] In the preparation of amorphous polyester resin (1), the loading of materials was changed as described below, and amorphous polyester resin (3) was obtained in the same manner otherwise.

[0359] ·Terephthalic acid: 80 moles

[0360] • Isophthalic acid: 10 moles

[0361] Fumaric acid: 10 moles

[0362] Ethylene glycol: 50 moles

[0363] Propylene glycol: 50 moles

[0364] The obtained amorphous polyester resin (3) has an ester group concentration of 45.0% by mass.

[0365] In the preparation of the amorphous polyester resin dispersion (1), the amorphous polyester resin (1) was changed to the amorphous polyester resin (3), and otherwise the amorphous polyester resin dispersion (3) with a solid content of 20% by mass was obtained in the same manner.

[0366] [Preparation of amorphous polyester resin dispersion (4) (PES4)]

[0367] In the preparation of amorphous polyester resin (1), the loading of materials was changed as described below, and amorphous polyester resin (4) was obtained in the same manner otherwise.

[0368] ·Terephthalic acid: 100 moles

[0369] Ethylene glycol: 60 moles

[0370] Propylene glycol: 5 moles

[0371] • Bisphenol A propylene oxide 2-molar adduct: 35 molar parts

[0372] The obtained amorphous polyester resin (4) has an ester group concentration of 30.0% by mass.

[0373] In the preparation of the amorphous polyester resin dispersion (1), the amorphous polyester resin (1) was changed to the amorphous polyester resin (4), and otherwise the amorphous polyester resin dispersion (4) with a solid content of 20% by mass was obtained in the same manner.

[0374] [Preparation of amorphous polyester resin dispersion (5) (PES5)]

[0375] In the preparation of amorphous polyester resin (1), the loading of materials was changed as described below, and amorphous polyester resin (5) was obtained in the same manner otherwise.

[0376] ·Terephthalic acid: 100 moles

[0377] Ethylene glycol: 5 moles

[0378] Propylene glycol: 5 moles

[0379] Neopentyl glycol: 40 moles

[0380] • Bisphenol A propylene oxide 2-molar adduct: 50 molar parts

[0381] The obtained amorphous polyester resin (5) has an ester group concentration of 25.0% by mass.

[0382] In the preparation of the amorphous polyester resin dispersion (1), the amorphous polyester resin (1) was changed to the amorphous polyester resin (5), and otherwise the amorphous polyester resin dispersion (5) with a solid content of 20% by mass was obtained in the same manner.

[0383] [Preparation of amorphous polyester resin dispersion (6) (PES6)]

[0384] In the preparation of amorphous polyester resin (1), the loading of materials was changed as described below, and amorphous polyester resin (6) was obtained in the same manner otherwise.

[0385] ·Terephthalic acid: 70 moles

[0386] • Adipic acid: 25 moles

[0387] Fumaric acid: 5 moles

[0388] Ethylene glycol: 35 moles

[0389] Propylene glycol: 30 moles

[0390] • Bisphenol A propylene oxide 2-molar adduct: 15 molar parts

[0391] • Bisphenol A ethylene oxide 2-molar adduct: 20 molar parts

[0392] The obtained amorphous polyester resin (6) has an ester group concentration of 31.0% by mass.

[0393] In the preparation of the amorphous polyester resin dispersion (1), the amorphous polyester resin (1) was changed to the amorphous polyester resin (6), and otherwise the amorphous polyester resin dispersion (6) with a solid content of 20% by mass was obtained in the same manner.

[0394] [Preparation of amorphous polyester resin dispersion (7) (PES7)]

[0395] In the preparation of amorphous polyester resin (1), the loading of materials was changed as described below, and amorphous polyester resin (7) was obtained in the same manner otherwise.

[0396] • Terephthalic acid: 68 moles

[0397] • Isophthalic acid: 20 moles

[0398] • Adipic acid: 12 moles

[0399] Ethylene glycol: 40 moles

[0400] Propylene glycol: 40 moles

[0401] Neopentyl glycol: 20 moles

[0402] The obtained amorphous polyester resin (7) had an ester group concentration of 43.0% by mass.

[0403] In the preparation of the amorphous polyester resin dispersion (1), the amorphous polyester resin (1) was changed to the amorphous polyester resin (7), and otherwise the amorphous polyester resin dispersion (7) with a solid content of 20% by mass was obtained in the same manner.

[0404] [Preparation of amorphous polyester resin dispersion (X)]

[0405] ·Terephthalic acid: 80 moles

[0406] • Dodecenylsuccinic acid: 20 moles

[0407] Propylene glycol: 10 moles

[0408] • Bisphenol A propylene oxide 2-molar adduct: 80 molar parts

[0409] • Bisphenol A ethylene oxide 2-molar adduct: 10 molar parts

[0410] The aforementioned material was loaded into a reaction vessel equipped with a stirring device, a nitrogen inlet pipe, a temperature sensor, and a distillation column. The temperature was raised to 190°C over 1 hour, and 1.2 parts of dibutyltin oxide were added relative to 100 parts of the aforementioned material. While distilling to remove the generated water, the temperature was raised to 240°C over 6 hours. Then, the temperature was maintained at 240°C for 3 hours to carry out a dehydration condensation reaction. After cooling, an amorphous polyester resin (X) was obtained.

[0411] The ester group concentration of the amorphous polyester resin (X) is 18.7% by mass.

[0412] In the preparation of the amorphous polyester resin dispersion (1), the amorphous polyester resin (1) was changed to the amorphous polyester resin (X), and otherwise the amorphous polyester resin dispersion (X) with a solid content of 20% by mass was obtained in the same manner.

[0413] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B2)]

[0414] <<Emulsion (2)>>

[0415] Styrene: 40 parts

[0416] • n-Butyl acrylate: 21.5 parts

[0417] Ethyl acrylate: 37 parts

[0418] • Divinylbenzene: 1.5 parts

[0419] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0420] • Ion-exchanged water: 98.8 parts

[0421] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (2).

[0422] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to emulsion (2), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (2) with a solid content concentration of 20% by mass was obtained in the same manner.

[0423] The obtained resin particles had an ester group concentration of 20.0% by mass.

[0424] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B3)]

[0425] <<Emulsion (3)>>

[0426] Styrene: 50 parts

[0427] • n-Butyl acrylate: 36 parts

[0428] • 2-Ethylhexyl acrylate: 12.5 parts

[0429] • Divinylbenzene: 1.5 parts

[0430] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0431] • Ion-exchanged water: 98.8 parts

[0432] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (3).

[0433] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (3), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (3) with a solid content concentration of 20% by mass was obtained in the same manner.

[0434] The ester group concentration of the obtained resin particles was 13.0% by mass.

[0435] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B4)]

[0436] <<Emulsion (4)>>

[0437] Styrene: 40.6 parts

[0438] • n-Butyl acrylate: 58.5 parts

[0439] • Divinylbenzene: 0.9 parts

[0440] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0441] • Ion-exchanged water: 98.8 parts

[0442] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (4).

[0443] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (4), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (4) with a solid content concentration of 20% by mass was obtained in the same manner.

[0444] The obtained resin particles had an ester group concentration of 17.0% by mass.

[0445] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B5)]

[0446] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the amount of anionic surfactant (ELEMINOL MON-2) added to the reaction vessel was changed from 0.4 parts to 1.2 parts. Otherwise, a styrene-(meth)acrylate copolymer particle dispersion (5) with a solid content concentration of 20% by mass was obtained in the same manner.

[0447] The obtained resin particles had an ester group concentration of 17.0% by mass.

[0448] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B6)]

[0449] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the amount of anionic surfactant (ELEMINOL MON-2) added to the reaction vessel was changed from 0.4 parts to 0.1 parts. Otherwise, a styrene-(meth)acrylate copolymer particle dispersion (6) with a solid content concentration of 20% by mass was obtained in the same manner.

[0450] The obtained resin particles had an ester group concentration of 17.0% by mass.

[0451] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B7)]

[0452] <<Emulsion (7)>>

[0453] Styrene: 45 parts

[0454] • n-Butyl acrylate: 10 parts

[0455] • 2-Ethylhexyl acrylate: 43.5 parts

[0456] • Divinylbenzene: 1.5 parts

[0457] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0458] • Ion-exchanged water: 98.8 parts

[0459] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (7).

[0460] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (7), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (7) with a solid content concentration of 20% by mass was obtained in the same manner.

[0461] The ester group concentration of the obtained resin particles was 11.7% by mass.

[0462] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B8)]

[0463] <<Emulsion (8)>>

[0464] Styrene: 48.5 parts

[0465] • n-Butyl acrylate: 39 parts

[0466] ·Ethylhexyl acrylate: 11 parts

[0467] • Divinylbenzene: 1.5 parts

[0468] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0469] • Ion-exchanged water: 98.8 parts

[0470] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (8).

[0471] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (8), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (8) with a solid content concentration of 20% by mass was obtained in the same manner.

[0472] The ester group concentration of the obtained resin particles was 13.6% by mass.

[0473] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B9)]

[0474] <<Emulsion (9)>>

[0475] Styrene: 40 parts

[0476] • n-Butyl acrylate: 20.5 parts

[0477] Ethyl acrylate: 38 parts

[0478] • Divinylbenzene: 1.5 parts

[0479] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0480] • Ion-exchanged water: 98.8 parts

[0481] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (9).

[0482] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (9), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (9) with a solid content concentration of 20% by mass was obtained in the same manner.

[0483] The ester group concentration of the obtained resin particles was 20.1% by mass.

[0484] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B10)]

[0485] <<Emulsion (10)>>

[0486] Styrene: 37 parts

[0487] • n-Butyl acrylate: 15 parts

[0488] Ethyl acrylate: 46.5 parts

[0489] • Divinylbenzene: 1.5 parts

[0490] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0491] • Ion-exchanged water: 98.8 parts

[0492] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (10).

[0493] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (10), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (10) with a solid content concentration of 20% by mass was obtained in the same manner.

[0494] The ester group concentration of the obtained resin particles was 21.7% by mass.

[0495] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B11)]

[0496] <<Emulsion (11)>>

[0497] Styrene: 41.5 parts

[0498] • n-Butyl acrylate: 58.5 parts

[0499] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0500] • Ion-exchanged water: 98.8 parts

[0501] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (11).

[0502] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (11), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (11) with a solid content concentration of 20% by mass was obtained in the same manner.

[0503] The obtained resin particles had an ester group concentration of 17.0% by mass.

[0504] [Preparation of (meth)acrylate resin particle dispersion (B12)]

[0505] <<Emulsion (12)>>

[0506] • Dodecyl acrylate: 98.5 parts

[0507] • Divinylbenzene: 1.5 parts

[0508] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0509] • Ion-exchanged water: 98.8 parts

[0510] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (12).

[0511] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (12), and otherwise, a (meth)acrylate copolymer particle dispersion (12) with a solid content concentration of 20% by mass was obtained in the same manner.

[0512] The ester group concentration of the obtained resin particles was 15.3% by mass.

[0513] [Preparation of styrene-(meth)acrylate copolymer particle dispersion (B13)]

[0514] <<Emulsion (13)>>

[0515] Styrene: 61 parts

[0516] • n-Butyl acrylate: 37.5 parts

[0517] • Divinylbenzene: 1.5 parts

[0518] • Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0519] • Ion-exchanged water: 98.8 parts

[0520] The above materials were loaded into a mixing container equipped with a stirring device and stirred to prepare an emulsion (13).

[0521] In the preparation of the styrene-(meth)acrylate copolymer particle dispersion (1), the emulsion (1) was changed to the emulsion (13), and otherwise, a styrene-(meth)acrylate copolymer particle dispersion (13) with a solid content concentration of 20% by mass was obtained in the same manner.

[0522] The ester group concentration of the obtained resin particles was 10.9% by mass.

[0523] [Preparation of release agent particle dispersion (2)]

[0524] In the preparation of the release agent particle dispersion (1), paraffin w1 was replaced with ester wax w2 (trade name: WEP-3, manufactured by NOFCORPORATION, ester concentration: 6.6% by mass, melting point: 72°C), and otherwise, a release agent particle dispersion (2) with a solid content of 20% by mass was obtained in the same manner.

[0525] [Preparation of release agent particle dispersion (3)]

[0526] In the preparation of the release agent particle dispersion (1), paraffin w1 was replaced with ester wax w3 (trade name: WEP-6, manufactured by NOFCORPORATION, ester concentration: 14.4% by mass, melting point: 77°C), and otherwise, a release agent particle dispersion (3) with a solid content of 20% by mass was obtained in the same manner.

[0527] [Preparation of release agent particle dispersion (4)]

[0528] In the preparation of the release agent particle dispersion (1), paraffin w1 was replaced with paraffin w4 (trade name: SP-1039, manufactured by NIPPON SEIRO CO.,LTD., ester concentration: 0% by mass, melting point: 60°C), and otherwise, a release agent particle dispersion (4) with a solid content of 20% by mass was obtained in the same manner.

[0529] [Preparation of release agent particle dispersion (5)]

[0530] In the preparation of the release agent particle dispersion (1), paraffin w1 was replaced with polyethylene wax w5 (trade name: HI-WAX420P, manufactured by Mitsui Chemicals, Inc., ester concentration: 0% by mass, melting point: 116°C), and otherwise, a release agent particle dispersion (5) with a solid content of 20% by mass was obtained in the same manner.

[0531] [Preparation of release agent particle dispersion (6)]

[0532] In the preparation of the release agent particle dispersion (1), paraffin w1 was replaced with fatty acid amide wax w6 (trade name: fatty acid amide S, manufactured by Kao Corporation, ester concentration: 0% by mass, melting point: 100°C), and otherwise, a release agent particle dispersion (6) with a solid content of 20% by mass was obtained in the same manner.

[0533] [Preparation of release agent particle dispersion (7)]

[0534] In the preparation of the release agent particle dispersion (1), paraffin w1 was replaced with polyethylene wax w7 (trade name: Polywax 625, manufactured by NuCera Solutions, ester concentration: 0% by mass, melting point: 99°C), and otherwise, a release agent particle dispersion (7) with a solid content of 20% by mass was obtained in the same manner.

[0535] <Methods for Determining Ester Group Concentration>

[0536] The ester concentration can be calculated based on the number of ester groups [-C(=O)O-] in the resin or compound, specifically, by the following formula.

[0537] Ester concentration (mass%) = (N × 44) / number average molecular weight × 100

[0538] Where N is the average number of ester groups per molecule, and 44 is the formula weight of the ester group [-C(=O)O-].

[0539] The composition of the monomers or the chemical structure and number of ester groups of the compounds were determined and calculated using nuclear magnetic resonance spectroscopy (NMR).

[0540] <Evaluation of Fixing Performance and Inhibition of Concentration Inhomogeneity under High Humidity Environments>

[0541] The paper (GR100; manufactured by FUJIFILM Business Innovation Corp.) was evaluated using Apeos C7070 (manufactured by FUJIFILM Business Innovation Corp.) after being opened and stored for one week at 25°C / 80% RH.

[0542] Specifically, 100 solid images of 20mm×20mm were printed consecutively, and the presence or absence of fixing defects was visually assessed.

[0543] A: No fixing defects were found in any of the 100 images.

[0544] B: Minor fixing defects occur in fewer than 3 out of 100 images.

[0545] C: More than 4 out of 100 images showed poor fixing.

[0546] Furthermore, regarding image defects, 10,000 A4-sized images with vertically striped solid images were printed at 25°C / 80% RH. The printed halftone (30%) images were then evaluated. In the halftone (30%) images, the difference between the average image density of five points corresponding to the locations of the previously printed 10,000 striped images and the average density of five points corresponding to the non-image areas of the striped images was evaluated. Image density was also measured using X-Rite 404 (manufactured by X-Rite, Inc.).

[0547] A: The density difference between the image area and the non-image area is less than 0.02, resulting in a uniform image.

[0548] B: The density difference between the image area and the non-image area is greater than 0.02 and less than 0.05, which is an almost imperceptible level of inhomogeneity.

[0549] C: A density difference of 0.05 or more and less than 0.10 between the image area and the non-image area is an acceptable level.

[0550] D: A density difference of 0.10 or more between the image area and the non-image area is an unacceptable level.

[0551]

[0552] As shown in Table 1, compared with the electrostatic image developing toner of the comparative example, the electrostatic image developing toner of the embodiment has excellent suppression of concentration non-uniformity under high humidity environment.

[0553] (1) A toner for electrostatic image development, comprising toner particles including a binder resin, a release agent and resin particles forming domains within the toner particles, wherein the binder resin comprises a polyester resin, the average ester concentration c1 of the binder resin is 25% by mass or more and 48% by mass or less, and when the ester concentration of the resin particles is set to c2, the value of c2 / c1 is 0.30 or more and 0.70 or less.

[0554] (2) The toner for electrostatic image development according to (1), wherein,

[0555] The content of the release agent is more than 1% by mass and less than 10% by mass relative to the total mass of the colorant particles.

[0556] (3) The electrostatic image developing toner according to (1) or (2), wherein,

[0557] When the content of the release agent in the colorant particles is set as Ww and the content of the resin particles is set as Wb, the value of Wb / Ww is 0.3 or more and 5.0 or less.

[0558] (4) The electrostatic image developing toner according to any one of (1) to (3), wherein,

[0559] The average circular equivalent diameter of the domain formed by the resin particles is greater than 50 nm and less than 300 nm.

[0560] (5) The toner for electrostatic image development according to any one of (1) to (4), wherein,

[0561] The release agent has a melting point above 60°C and below 120°C.

[0562] (6) The electrostatic image developing toner according to any one of (1) to (5), wherein,

[0563] The resin particles are styrene (meth)acrylic resin particles.

[0564] (7) The electrostatic image developing toner according to any one of (1) to (6), wherein,

[0565] The resin particles are cross-linked resin particles.

[0566] (8) The electrostatic image developing toner according to any one of (1) to (7), wherein,

[0567] The resin particles contain more than 80% by mass of tetrahydrofuran-insoluble components.

[0568] (9) The toner for electrostatic image development according to any one of (1) to (8), wherein,

[0569] The release agent comprises at least one selected from the group consisting of hydrocarbon waxes and ester waxes.

[0570] (10) The toner for electrostatic image development according to any one of (1) to (9), wherein,

[0571] The ester group concentration (c3) of the release agent is less than 15% by mass.

[0572] (11) An electrostatic image developer comprising any one of (1) to (10) an electrostatic image developer toner.

[0573] (12) A toner cartridge containing an electrostatic image developing toner as described in any one of (1) to (10), and detachable from an image forming apparatus.

[0574] (13) A processing cartridge comprising a developing apparatus, the developing apparatus containing the electrostatic image developer of (11), and developing an electrostatic image formed on the surface of an image holder into a toner image using the electrostatic image developer, the processing cartridge being detachable from an image forming apparatus.

[0575] (14) An image forming apparatus comprising: an image holding body; a charging device for charging the surface of the image holding body; an electrostatic image forming apparatus for forming an electrostatic image on the charged surface of the image holding body; a developing apparatus for receiving the electrostatic image developer of (11) and developing the electrostatic image formed on the surface of the image holding body into a toner image using the electrostatic image developer; a transfer apparatus for transferring the toner image formed on the surface of the image holding body to the surface of a recording medium; and a fixing apparatus for fixing the toner image transferred to the surface of the recording medium.

[0576] (15) An image forming method, comprising: a charging step, charging the surface of an image holder; an electrostatic image forming step, forming an electrostatic image on the charged surface of the image holder; a developing step, developing the electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer of (11); a transfer step, transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step, fixing the toner image transferred to the surface of the recording medium.

[0577] According to the invention involved in (1) or (9), a toner for electrostatic image development is provided that exhibits excellent suppression of concentration non-uniformity under high humidity conditions, compared to toner particles having resin particles comprising a binder resin, a release agent and resin particles forming a domain within the toner particles. The binder resin comprises a polyester resin, and the average ester concentration c1 of the binder resin is less than 25% by mass or more than 48% by mass, or when the ester concentration of the resin particles is set to c2, the value of c2 / c1 is less than 0.30 or more than 0.70.

[0578] According to the invention involved in (2), a toner for electrostatic image development is provided in which the content of the release agent is less than 1% by mass or more than 10% by mass relative to the total mass of the toner particles, exhibiting superior suppression of concentration inhomogeneity under high humidity conditions.

[0579] According to the invention involved in (3), a colorant for electrostatic image development is provided that has better suppression of concentration non-uniformity under high humidity conditions compared to cases where the content of the release agent in the colorant particles is set to Ww and the content of the resin particles is set to Wb, and the value of Wb / Ww is less than 0.3 or more than 5.0.

[0580] According to the invention involved in (4), a colorant for electrostatic image development is provided that exhibits superior suppression of concentration inhomogeneity under high humidity conditions compared to cases where the average circular equivalent diameter of the domains formed by the resin particles is less than 50 nm or more than 300 nm.

[0581] According to the invention involved in (5), a colorant for electrostatic image development is provided that has better suppression of concentration inhomogeneity under high humidity conditions compared to the release agent with a melting point of less than 60°C or more than 120°C.

[0582] According to the invention involved in (6), a colorant for electrostatic image development is provided that has better suppression of concentration unevenness under high humidity conditions compared to the case where the resin particles are polyester resin particles.

[0583] According to the invention involved in (7), a colorant for electrostatic image development is provided that has better suppression of concentration unevenness under high humidity conditions compared to the case where the resin particles are resin particles without cross-linking structure.

[0584] According to the invention involved in (8), a colorant for electrostatic image development is provided that exhibits superior inhibition of concentration inhomogeneity under high humidity conditions compared to the case where the tetrahydrofuran insoluble component of the resin particles is less than 80% by mass.

[0585] According to the invention involved in (10), a colorant for electrostatic image development is provided that exhibits superior suppression of concentration inhomogeneity under high humidity conditions compared to the case where the ester group concentration c3 of the release agent exceeds 15% by mass.

[0586] According to the inventions involved in (11), (12), (13), (14) or (15), an electrostatic image developer, a toner cartridge, a processing cartridge, an image forming apparatus or an image forming method is provided that exhibits excellent suppression of concentration non-uniformity under high humidity conditions compared to toners for electrostatic image development that use toner particles having resin particles comprising a binder resin, a release agent and a forming domain within the toner particles, wherein the binder resin comprises a polyester resin and the average ester concentration c1 of the binder resin is less than 25% by mass or more than 48% by mass, or where the ester concentration of the resin particles is set to c2 and the value of c2 / c1 is less than 0.30 or more than 0.70.

[0587] The embodiments of the present invention described above are provided for illustrative purposes. Furthermore, these embodiments do not encompass the entirety of the invention, nor do they limit the invention to the disclosed methods. It will be apparent to those skilled in the art that various modifications and variations will be readily understood. These embodiments were chosen and described to most readily explain the principles and applications of the invention. Thus, those skilled in the art can understand the invention through various modifications that are assumed to be optimized for specific uses of various embodiments. The scope of the invention is defined by the foregoing claims and their equivalents.

Claims

1. A toner for electrostatic image development, comprising toner particles including a binding resin, a release agent, and resin particles forming domains within the toner particles. The adhesive resin comprises polyester resin. The average ester concentration c1 of the bonding resin is 25% by mass or more and 48% by mass or less. When the ester group concentration of the resin particles is set to c2, the value of c2 / c1 is 0.30 or more and 0.70 or less.

2. The toner for electrostatic image development according to claim 1, wherein, The content of the release agent is more than 1% by mass and less than 10% by mass relative to the total mass of the colorant particles.

3. The toner for electrostatic image development according to claim 1 or 2, wherein, When the content of the release agent in the colorant particles is set as Ww and the content of the resin particles is set as Wb, the value of Wb / Ww is 0.3 or more and 5.0 or less.

4. The toner for electrostatic image development according to any one of claims 1 to 3, wherein, The average circular equivalent diameter of the domain formed by the resin particles is greater than 50 nm and less than 300 nm.

5. The toner for electrostatic image development according to any one of claims 1 to 4, wherein, The release agent has a melting point above 60°C and below 120°C.

6. The toner for electrostatic image development according to any one of claims 1 to 5, wherein, The resin particles are styrene (meth)acrylic resin particles.

7. The toner for electrostatic image development according to any one of claims 1 to 6, wherein, The resin particles are cross-linked resin particles.

8. The toner for electrostatic image development according to any one of claims 1 to 7, wherein, The resin particles contain more than 80% by mass of tetrahydrofuran-insoluble components.

9. The toner for electrostatic image development according to any one of claims 1 to 8, wherein, The release agent comprises at least one selected from the group consisting of hydrocarbon waxes and ester waxes.

10. The toner for electrostatic image development according to any one of claims 1 to 9, wherein, The ester group concentration (c3) of the release agent is less than 15% by mass.

11. An electrostatic image developer comprising a toner for electrostatic image development according to any one of claims 1 to 10.

12. A toner cartridge containing the toner for electrostatic image development as claimed in any one of claims 1 to 10, And it is mounted and dismounted from the image forming apparatus.

13. A processing cartridge comprising a developing apparatus, said developing apparatus containing the electrostatic image developer of claim 11, and using said electrostatic image developer to develop an electrostatic image formed on the surface of an image holder into a toner image. The processing box is mounted and dismounted from the image forming apparatus.

14. An image forming apparatus comprising: Image holding volume; The charging device charges the surface of the image holder. An electrostatic image forming apparatus forms an electrostatic image on the surface of the already charged image holder; A developing apparatus that contains the electrostatic image developer of claim 11 and develops an electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer; A transfer apparatus transfers a toner image formed on the surface of the image holder onto the surface of a recording medium; and A fixing device fixes the toner image that has been transferred onto the surface of the recording medium.

15. An image forming method, comprising: The charging process charges the surface of the image holder. The electrostatic image forming process forms an electrostatic image on the surface of the already charged image holder; The developing process uses the electrostatic image developer of claim 11 to develop the electrostatic image formed on the surface of the image holder into a toner image; The transfer process transfers the toner image formed on the surface of the image holder onto the surface of the recording medium; and The fixing process fixes the toner image that has been transferred to the surface of the recording medium.

Images